National Library of Energy BETA

Sample records for au rg zn

  1. Mechanical and Electrical Performance of Thermally Stable Au-ZnO films

    SciTech Connect (OSTI)

    Schoeppner, Rachel L.; Goeke, Ronald S.; Moody, Neville R.; Bahr, David F.

    2015-03-28

    The mechanical properties, thermal stability, and electrical performance of AuZnO composite thin films are determined in this work. The co-deposition of ZnO with Au via physical vapor deposition leads to grain refinement over that of pure Au; the addition of 0.1 vol.% ZnO reduces the as-grown grain size by over 30%. The hardness of the as-grown films doubles with 2% ZnO, from 1.8 to 3.6 GPa as measured by nanoindentation. Films with ZnO additions greater than 0.5% show no significant grain growth after annealing at 350 C, while pure gold and smaller additions do exhibit grain growth and subsequent mechanical softening. Films with 1% and 2% ZnO show a decrease of approximately 50% in electrical resistivity and no change in hardness after annealing. A model accounting for both changes in the interface structure between dispersed ZnO particles and the Au matrix captures the changes in mechanical and electrical resistivity. Furthermore, the addition of 12% ZnO co-deposited with Au provides a method to create mechanically hard and thermally stable films with a resistivity less than 80 n?-m. Our results complement previous studies of other alloying systems, suggesting oxide dispersion strengthened (ODS) gold shows a desirable hardnessresistivity relationship that is relatively independent of the particular ODS chemistry.

  2. Nanoscale mapping of plasmon and exciton in ZnO tetrapods coupled with Au nanoparticles

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Bertoni, Giovanni; Fabbri, Filippo; Villani, Marco; Lazzarini, Laura; Turner, Stuart; Van Tendeloo, Gustaaf; Calestani, Davide; Gradečak, Silvija; Zappettini, Andrea; Salviati, Giancarlo

    2016-01-12

    Metallic nanoparticles can be used to enhance optical absorption or emission in semiconductors, thanks to a strong interaction of collective excitations of free charges (plasmons) with electromagnetic fields. Herein we present direct imaging at the nanoscale of plasmon-exciton coupling in Au/ZnO nanostructures by combining scanning transmission electron energy loss and cathodoluminescence spectroscopy and mapping. The Au nanoparticles (~30 nm in diameter) are grown in-situ on ZnO nanotetrapods by means of a photochemical process without the need of binding agents or capping molecules, resulting in clean interfaces. Interestingly, the Au plasmon resonance is localized at the Au/vacuum interface, rather than presentingmore » an isotropic distribution around the nanoparticle. Moreover, on the contrary, a localization of the ZnO signal has been observed inside the Au nanoparticle, as also confirmed by numerical simulations.« less

  3. Growth of Single- and Bilayer ZnO on Au(111) and Interaction with Copper

    SciTech Connect (OSTI)

    Deng, Xingyi; Yao, Kun; Sun, Keju; Li, Wei-Xue; Lee, Junseok; Matranga, Christopher

    2013-05-30

    The stoichiometric single- and bi-layer ZnO(0001) have been prepared by reactive deposition of Zn on Au(111) and studied in detail with X-ray photoelectron spectroscopy, scanning tunneling microscopy, and density functional theory calculations. Both single- and bi-layer ZnO(0001) adopt a planar, graphite-like structure similar to freestanding ZnO(0001) due to the weak van der Waals interactions dominating their adhesion with the Au(111) substrate. At higher temperature, the single-layer ZnO(0001) converts gradually to bi-layer ZnO(0001) due to the twice stronger interaction between two ZnO layers than the interfacial adhesion of ZnO with Au substrate. It is found that Cu atoms on the surface of bi-layer ZnO(0001) are mobile with a diffusion barrier of 0.31 eV, and likely to agglomerate and form nanosized particles at low coverages; while Cu atoms tend to penetrate a single layer of ZnO(0001) with a barrier of 0.10 eV, resulting in a Cu free surface.

  4. Mechanical and Electrical Performance of Thermally Stable Au-ZnO films

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Schoeppner, Rachel L.; Goeke, Ronald S.; Moody, Neville R.; Bahr, David F.

    2015-03-28

    The mechanical properties, thermal stability, and electrical performance of Au–ZnO composite thin films are determined in this work. The co-deposition of ZnO with Au via physical vapor deposition leads to grain refinement over that of pure Au; the addition of 0.1 vol.% ZnO reduces the as-grown grain size by over 30%. The hardness of the as-grown films doubles with 2% ZnO, from 1.8 to 3.6 GPa as measured by nanoindentation. Films with ZnO additions greater than 0.5% show no significant grain growth after annealing at 350 °C, while pure gold and smaller additions do exhibit grain growth and subsequent mechanicalmore » softening. Films with 1% and 2% ZnO show a decrease of approximately 50% in electrical resistivity and no change in hardness after annealing. A model accounting for both changes in the interface structure between dispersed ZnO particles and the Au matrix captures the changes in mechanical and electrical resistivity. Furthermore, the addition of 1–2% ZnO co-deposited with Au provides a method to create mechanically hard and thermally stable films with a resistivity less than 80 nΩ-m. Our results complement previous studies of other alloying systems, suggesting oxide dispersion strengthened (ODS) gold shows a desirable hardness–resistivity relationship that is relatively independent of the particular ODS chemistry.« less

  5. Mechanical and Electrical Performance of Thermally Stable Au-ZnO films

    SciTech Connect (OSTI)

    Schoeppner, Rachel L.; Goeke, Ronald S.; Moody, Neville R.; Bahr, David F.

    2015-03-28

    The mechanical properties, thermal stability, and electrical performance of Au–ZnO composite thin films are determined in this work. The co-deposition of ZnO with Au via physical vapor deposition leads to grain refinement over that of pure Au; the addition of 0.1 vol.% ZnO reduces the as-grown grain size by over 30%. The hardness of the as-grown films doubles with 2% ZnO, from 1.8 to 3.6 GPa as measured by nanoindentation. Films with ZnO additions greater than 0.5% show no significant grain growth after annealing at 350 °C, while pure gold and smaller additions do exhibit grain growth and subsequent mechanical softening. Films with 1% and 2% ZnO show a decrease of approximately 50% in electrical resistivity and no change in hardness after annealing. A model accounting for both changes in the interface structure between dispersed ZnO particles and the Au matrix captures the changes in mechanical and electrical resistivity. Furthermore, the addition of 1–2% ZnO co-deposited with Au provides a method to create mechanically hard and thermally stable films with a resistivity less than 80 nΩ-m. Our results complement previous studies of other alloying systems, suggesting oxide dispersion strengthened (ODS) gold shows a desirable hardness–resistivity relationship that is relatively independent of the particular ODS chemistry.

  6. Hydrothermal synthesis of coral-like Au/ZnO catalyst and photocatalytic degradation of Orange II dye

    SciTech Connect (OSTI)

    Chen, P.K.; Lee, G.J.; Davies, S.H.; Masten, S.J.; Amutha, R.; Wu, J.J.

    2013-06-01

    Highlights: ? Coral-like Au/ZnO was successfully prepared using green synthetic method. ? Gold nanoparticles were deposited on the ZnO structure using NaBH{sub 4} and ?-D-glucose. ? Coral-like Au/ZnO exhibited superior photocatalytic activity to degrade Orange II. - Abstract: A porous coral-like zinc oxide (c-ZnO) photocatalyst was synthesized by the hydrothermal method. The coral-like structure was obtained by precipitating Zn{sub 4}(CO{sub 3})(OH){sub 6}H{sub 2}O (ZnCH), which forms nanosheets that aggregate together to form microspheres with the coral-like structure. X-ray diffraction (XRD) studies indicate that after heating at 550 C the ZnCH microspheres can be converted to ZnO microspheres with a morphology similar to that of ZnCH microspheres. Thermogravimetric analysis (TGA) shows this conversion takes place at approximately 260 C. A simple electrostatic self-assembly method has been employed to uniformly disperse Au nanoparticles (1 wt.%) on the ZnO surface. In this procedure ?-D-glucose was used to stabilize the Au nanoparticles. Scanning electron microscope images indicate that the diameter of coral-like ZnO microspheres (c-ZnO) is about 8 ?m. X-ray diffraction reveals that the ZnO is highly crystalline with a wurtzite structure and the Au metallic particles have an average size of about 13 nm. X-ray photoelectron spectroscopic (XPS) studies have confirmed the presence of ZnO and also showed that the Au is present in the metallic state. The photocatalytic degradation of Orange II dye, with either ultraviolet or visible light, is faster on Au/c-ZnO than on c-ZnO.

  7. Visible light plasmonic heating of Au-ZnO for the catalytic reduction of CO2

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Wang, Congjun; Ranasingha, Oshadha; Natesakhawat, Sittichai; Ohodnicki, Paul R.; Andio, Mark; Lewis, James P.; Matranga, Christopher

    2013-01-01

    Plasmonic excitation of Au nanoparticles attached to the surface of ZnO catalysts using low power 532 nm laser illumination leads to significant heating of the catalyst and the conversion of CO2 and H2 reactants to CH4 and CO products. Temperature-calibrated Raman spectra of ZnO phonons show that intensity-dependent plasmonic excitation can controllably heat Au–ZnO from 30 to ~600 °C and simultaneously tune the CH4 : CO product ratio. The laser induced heating and resulting CH4 : CO product distribution agrees well with predictions from thermodynamic models and temperature-programmed reaction experiments indicating that the reaction is a thermally driven process resultingmore » from the plasmonic heating of the Au-ZnO. The apparent quantum yield for CO2 conversion under continuous wave (cw) 532 nm laser illumination is 0.030%. The Au-ZnO catalysts are robust and remain active after repeated laser exposure and cycling. The light intensity required to initiate CO2 reduction is low ( ~2.5 x 105 W m-2) and achievable with solar concentrators. Our results illustrate the viability of plasmonic heating approaches for CO2 utilization and other practical thermal catalytic applications.« less

  8. Structural Phase Transition in AuZn Alloys

    SciTech Connect (OSTI)

    Winn,B.L.; Shapiro, S.M.; Lashley, J.C.; Opeil, C.; Ratcliff, W.

    2009-05-03

    AuxZn1-x alloys undergo a shape memory martensitic transformation whose temperature and nature (continuous or discontinuous) is strongly composition dependent. Neutron diffraction experiments were performed on single crystals of x=50 and 52 to explore the structural changes occurring at the transition temperature. A transverse modulation with wavevector q0=(1/3,1/3,0) develops below the transition temperature, with no observable change in lattice parameter. However, the Bragg peak width shows a broadening suggesting an unresolved rhombohedral distortion similar to what has been observed in NiTi-Fe alloys.

  9. Oxidation of palladium on Au(111) and ZnO(0001) supports

    SciTech Connect (OSTI)

    Lallo, J.; Tenney, S. A.; Kramer, A.; Sutter, P.; Batzill, M.

    2014-10-21

    The oxidation of supported Pd-deposits on Au(111) and ZnO(0001) single crystals has been studied by x- ray photoemission spectroscopy (XPS). Oxidation has been carried out ex-situ in a high-pressure cell with subsequent vacuum-transfer and characterization by XPS in ultrahigh vacuum (UHV), as well as using in-situ characterization by synchrotron based near-ambient pressure XPS. On Au(111) alloying of Pd with the substrate competes with oxidation and only sufficiently thick Pd films have been found to oxidize. For Pd on ZnO the oxidation conditions depend on the amount of deposited Pd. Thicker Pd deposits behave similar to bulk Pd, while thinner films oxidize already at lower temperatures. Interestingly, for very small amounts of Pd, in-situ XPS shows full oxidation at room temperature and at less than 0.6 mbar O? pressure. This indicates a lowering of the kinetic barriers for oxidation of very small supported Pd-clusters. The formed oxide is, however, not stable in UHV and a slow reduction is observed. The instability of this oxide indicates that the Pd-oxide formed at the interface to ZnO may have different chemical properties compared to bulk PdO or surface oxides on Pd.

  10. Oxidation of palladium on Au(111) and ZnO(0001) supports

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Lallo, J.; Tenney, S. A.; Kramer, A.; Sutter, P.; Batzill, M.

    2014-10-21

    The oxidation of supported Pd-deposits on Au(111) and ZnO(0001) single crystals has been studied by x- ray photoemission spectroscopy (XPS). Oxidation has been carried out ex-situ in a high-pressure cell with subsequent vacuum-transfer and characterization by XPS in ultrahigh vacuum (UHV), as well as using in-situ characterization by synchrotron based near-ambient pressure XPS. On Au(111) alloying of Pd with the substrate competes with oxidation and only sufficiently thick Pd films have been found to oxidize. For Pd on ZnO the oxidation conditions depend on the amount of deposited Pd. Thicker Pd deposits behave similar to bulk Pd, while thinner filmsmore » oxidize already at lower temperatures. Interestingly, for very small amounts of Pd, in-situ XPS shows full oxidation at room temperature and at less than 0.6 mbar O₂ pressure. This indicates a lowering of the kinetic barriers for oxidation of very small supported Pd-clusters. The formed oxide is, however, not stable in UHV and a slow reduction is observed. The instability of this oxide indicates that the Pd-oxide formed at the interface to ZnO may have different chemical properties compared to bulk PdO or surface oxides on Pd.« less

  11. Visible light plasmonic heating of Au-ZnO for the catalytic reduction of CO{sub 2}

    SciTech Connect (OSTI)

    Wang, Congjun; Ranasingha, Oshadha; Natesakhawat, Sittichai; Ohodnicki, Paul R.; Ohodnicki, Andio, Mark; Lewis, James; P Matranga, Christopher

    2013-05-01

    Plasmonic excitation of Au nanoparticles attached to the surface of ZnO catalysts using low power 532 nm laser illumination leads to significant heating of the catalyst and the conversion of CO{sub 2} and H{sub 2} reactants to CH{sub 4} and CO products. Temperature-calibrated Raman spectra of ZnO phonons show that intensity-dependent plasmonic excitation can controllably heat AuZnO from 30 to #1;~600 {degrees}#3;C and simultaneously tune the CH{sub 4} : CO product ratio. The laser induced heating and resulting CH{sub 4} : CO product distribution agrees well with predictions from thermodynamic models and temperatureprogrammed reaction experiments indicating that the reaction is a thermally driven process resulting from the plasmonic heating of the AuZnO. The apparent quantum yield for CO{sub 2} conversion under continuous wave (cw) 532 nm laser illumination is 0.030%. The AuZnO catalysts are robust and remain active after repeated laser exposure and cycling. The light intensity required to initiate CO{sub 2} reduction is low (#1;~2.5 x#4; 10{sup 5} W m{sup #5;-2}) and achievable with solar concentrators. Our results illustrate the viability of plasmonic heating approaches for CO{sub 2} utilization and other practical thermal catalytic applications.

  12. The effect of Au and Ni doping on the heavy fermion state of the Kondo lattice antiferromagnet CePtZn

    SciTech Connect (OSTI)

    Dhar, S. K.; Aoki, Y.; Suemitsu, B.; Miyazaki, R.; Provino, A.; Manfrinetti, P.

    2014-05-07

    We have probed the effect of doping CePtZn with Au and Ni and also investigated in detail the magnetic behavior of the iso-structural CeAuZn. A magnetic ground state is observed in both CePt{sub 0.9}Au{sub 0.1}Zn and CePt{sub 0.9}Ni{sub 0.1}Zn with T{sub N}?=?2.1 and 1.1?K and the coefficient of the linear term of electronic heat capacity ??=?0.34 and 0.9?J/mol K{sup 2}, respectively. The corresponding values for CePtZn are 1.7?K and 0.6?J/mol K{sup 2}. The altered values of T{sub N} and ? show that the electronic correlations in CePtZn are affected by doping with Au and Ni. CeAuZn orders magnetically near 1.7?K and its electrical resistivity shows a normal metallic behavior. Together with a ? of 0.022?J/mol K{sup 2} the data indicate a weak 4f-conduction electron hybridization in CeAuZn characteristic of normal trivalent cerium based systems.

  13. Wavelengths, transition probabilities, and oscillator strengths for M-shell transitions in Co-, Ni-, Cu-, Zn-, Ga-, Ge-, and Se-like Au ions

    SciTech Connect (OSTI)

    Xu, Min; Jiang, Gang; Deng, Banglin; Bian, Guojie

    2014-11-15

    Wavelengths, transition probabilities, and oscillator strengths have been calculated for M-shell electric dipole transitions in Co-, Ni-, Cu-, Zn-, Ga-, Ge-, and Se-like Au ions. The fully relativistic multiconfiguration Dirac–Fock method, taking quantum electrodynamical effects and the Breit correction into account, was used in the calculations. Calculated energy levels of M-shell excited states for Cu-, Zn-, Ga-, Ge-, and Se-like Au ions from the method were compared with available theoretical and experimental results, and good agreement with them was achieved.

  14. D= DOE/RG-0067

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    D= DOE/RG-0067 o y e= New England/Hydro-Quebec ± 450 kv Transmission Line Interconnection-- Phase II U.S. Department of Energy Economic Regulatory Administration Office of Fuels Programs August 1986 DClE/E I S-*0 l29D This report has been reproduced directly from the best available copy. Available from the National Technical Information Service, U.S. Department of Commerce, Springfield, Virginia 22161. Price: Printed Copy Al3 Microfiche A01 Codes are used for pricing all publications. The code

  15. Photoluminescence Enhancement in CdSe/ZnSDNA linkedAu Nanoparticle Heterodimers Probed by Single Molecule Spectroscopy

    SciTech Connect (OSTI)

    Cotlet, M.; Maye, M.M.; Gang, O.

    2010-07-26

    Photoluminescence enhancement of up to 20 fold is demonstrated at the single molecule level for heterodimers composed of a core/shell CdSe/ZnS semiconductive quantum dot and a gold nanoparticle of 60 nm size separated by a 32 nm-long dsDNA linker when employing optical excitation at wavelengths near the surface plasmon resonance of the gold nanoparticle.

  16. Boundary Entropy Can Increase Under Bulk RG Flow (Journal Article...

    Office of Scientific and Technical Information (OSTI)

    Boundary Entropy Can Increase Under Bulk RG Flow Citation Details In-Document Search Title: Boundary Entropy Can Increase Under Bulk RG Flow The boundary entropy log(g) of a critical ...

  17. Boundary Entropy Can Increase Under Bulk RG Flow (Journal Article...

    Office of Scientific and Technical Information (OSTI)

    Boundary Entropy Can Increase Under Bulk RG Flow Citation Details In-Document Search Title: Boundary Entropy Can Increase Under Bulk RG Flow You are accessing a document from ...

  18. RG&E (Electric)- Commercial and Industrial Efficiency Program

    Broader source: Energy.gov [DOE]

    NYSEG and RG&E offer rebates to non-residential customers installing energy efficient equipment that have an electricity Systems Benefits Charge (SBC) included in their energy bills. Both...

  19. RG&E (Gas)- Commercial and Industrial Efficiency Program

    Broader source: Energy.gov [DOE]

    NYSEG and RG&E offer rebates to non-residential customers installing energy efficiency equipment who pay a natural gas Systems Benefits Charge (SBC). Both prescriptive rebates and custom...

  20. AU Organizational chart

    Office of Environmental Management (EM)

    Debra J. Rosano Acting Director AU-22 Edward P. Regnier Director AU-23 Colette A. Broussard Director AU-30 Garrett A. Smith Jr Acting Director AU-31 Pranab K. Guha Acting Director ...

  1. LAKESHORE AVON BR ANT-EDEN ALD EN-LANC ASTER AU BURN W SH ELDON

    U.S. Energy Information Administration (EIA) Indexed Site

    81 § ¨ ¦ 81 LAKESHORE AVON BR ANT-EDEN ALD EN-LANC ASTER AU BURN W SH ELDON CALEDONIA HURON C REEK LEIC EST ER COL DEN ASH FORD INDIAN FALLS LAWTONS SAR DINIA RPD-037 -2 GLENWOOD PU LASKI PAVILION CON CORD COL LINS N ELM A ORC HARD PARK-H AMBU RG DANLEY CORNERS ST ILLWAT ER CHAFF EE-ARCAD E FAYETT E-WATERLOO LAKEVIEW JAVA SEN EC A W ELLER Y AU RORA E ZOAR BU FFALO TIOGA SILVER LAKE AKR ON ROM E RAT HBON E ALM A BET HANY WYOMING ULYSSES BR ANCH W SAN DY CREEK COL LINS BLOOMFIELD E LEBANON

  2. Simulation of Electric Field in Semi Insulating Au/CdTe/Au Detector under Flux

    SciTech Connect (OSTI)

    Franc, J.; James, R.; Grill, R.; Kubat, J.; Belas, E.; Hoschl, P.; Moravec, P.; Praus, P.

    2009-08-02

    We report our simulations on the profile of the electric field in semi insulating CdTe and CdZnTe with Au contacts under radiation flux. The type of the space charge and electric field distribution in the Au/CdTe/Au structure is at high fluxes result of a combined influence of charge formed due to band bending at the electrodes and from photo generated carriers, which are trapped at deep levels. Simultaneous solution of drift-diffusion and Poisson equations is used for the calculation. We show, that the space charge originating from trapped photo-carriers starts to dominate at fluxes 10{sup 15}-10{sup 16}cm{sup -2}s{sup -1}, when the influence of contacts starts to be negligible.

  3. Ginsenoside Rg3 regulates S-nitrosylation of the NLRP3 inflammasome via suppression of iNOS

    SciTech Connect (OSTI)

    Yoon, Sung-Jin; Park, Jun-Young; Choi, Song; Lee, Jin-Bong; Jung, Haiyoung; Kim, Tae-Don; Yoon, Suk Ran; Choi, Inpyo; Shim, Sungbo; Park, Young-Jun

    2015-08-07

    Ginsenoside Rg3, a specific biological effector, is well-known as a major bioactive ingredient of Panax ginseng. However, its role in the inflammasome activation process remains unclear. In this report, we demonstrate that ginsenosides 20(R)-Rg3 and 20(S)-Rg3 are capable of suppressing both lethal endotoxic shock and the S-nitrosylation of the NLRP3 inflammasome by inhibiting nitric oxide (NO) production through the regulation of inducible nitric oxide synthase (iNOS) expression. In response to lipopolysaccharide (LPS), the reducing effect of 20(S)-Rg3 and 20(R)-Rg3 on nitric oxide led to an increase in the survival time of mice after lethal endotoxin-induced shock, and excess levels of NO inhibited IL-1β production via the S-nitrosylation of the NLRP3 inflammasome. In addition, ginsenosides 20(R)-Rg3 and 20(S)-Rg3 had suppressive effects on the LPS- or UV-irradiation-induced reactive oxygen species (ROS) levels in macrophage and HaCaT cells and thereby prevented apoptosis of spleen cells in mice. Altogether, these results demonstrate that ginsenoside 20(R)-Rg3 and 20(S)-Rg3, a naturally occurring compound, might act as a dual therapeutic regulator for the treatment of inflammatory and oxidative stress-related diseases. - Highlights: • Ginsenosides Rg3 inhibits NO production through the regulation of iNOS expression. • Ginsenosides Rg3 inhibits the S-nitrosylation of the NLRP3 inflammasome. • Ginsenosides Rg3 suppress on the LPS- or UV-irradiation-induced ROS levels in cells.

  4. Microsoft Word - RBL_Jan_2009_RG13-1-398.doc

    Office of Legacy Management (LM)

    13-1-398 Well: Gas production well, Federal RG 13-1-398, API # 05-103-10605. Operator: Williams Production RMT, Incorporated Sampler: U.S. Department of Energy, Office of Legacy Management, Grand Junction, CO. Date of Sampling Event: 7 January 2009 Samples of natural gas and produced water were collected from production well Federal RG 13-1-398. Location data for the surface collection point and the sample location are given in Table 1. A description of each sample collected is listed in Table

  5. Microsoft Word - RBL_Jan_2009_RG24-13-398.doc

    Office of Legacy Management (LM)

    24-13-398 Well: Gas production well, Federal RG 24-13-398, API # 05-103-10702. Operator: Williams Production RMT, Incorporated Sampler: U.S. Department of Energy, Office of Legacy Management, Grand Junction, CO. Date of Sampling Event: 7 January 2009 Samples of natural gas and produced water were collected from production well Federal RG 24-13-398. Location data for the surface collection point and the sample location are given in Table 1. A description of each sample collected is listed in

  6. Photoluminescence study of the substitution of Cd by Zn during the growth by atomic layer epitaxy of alternate CdSe and ZnSe monolayers

    SciTech Connect (OSTI)

    Hernndez-Caldern, I.; Salcedo-Reyes, J. C.

    2014-05-15

    We present a study of the substitution of Cd atoms by Zn atoms during the growth of alternate ZnSe and CdSe compound monolayers (ML) by atomic layer epitaxy (ALE) as a function of substrate temperature. Samples contained two quantum wells (QWs), each one made of alternate CdSe and ZnSe monolayers with total thickness of 12 ML but different growth parameters. The QWs were studied by low temperature photoluminescence (PL) spectroscopy. We show that the Cd content of underlying CdSe layers is affected by the exposure of the quantum well film to the Zn flux during the growth of ZnSe monolayers. The amount of Cd of the quantum well film decreases with higher exposures to the Zn flux. A brief discussion about the difficulties to grow the Zn{sub 0.5}Cd{sub 0.5}Se ordered alloy (CuAu-I type) by ALE is presented.

  7. Magnetic susceptibilities of liquid Cr-Au, Mn-Au and Fe-Au alloys

    SciTech Connect (OSTI)

    Ohno, S.; Shimakura, H.; Tahara, S.; Okada, T.

    2015-08-17

    The magnetic susceptibility of liquid Cr-Au, Mn-Au, Fe-Au and Cu-Au alloys was investigated as a function of temperature and composition. Liquid Cr{sub 1-c}Au{sub c} with 0.5 ≤ c and Mn{sub 1-c}Au{sub c} with 0.3≤c obeyed the Curie-Weiss law with regard to their dependence of χ on temperature. The magnetic susceptibilities of liquid Fe-Au alloys also exhibited Curie-Weiss behavior with a reasonable value for the effective number of Bohr magneton. On the Au-rich side, the composition dependence of χ for liquid TM-Au (TM=Cr, Mn, Fe) alloys increased rapidly with increasing TM content, respectively. Additionally, the composition dependences of χ for liquid Cr-Au, Mn-Au, and Fe-Au alloys had maxima at compositions of 50 at% Cr, 70 at% Mn, and 85 at% Fe, respectively. We compared the composition dependences of χ{sub 3d} due to 3d electrons for liquid binary TM-M (M=Au, Al, Si, Sb), and investigated the relationship between χ{sub 3d} and E{sub F} in liquid binary TM-M alloys at a composition of 50 at% TM.

  8. Magnetoresistance of Au films

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Zhang, D. L.; Song, X. H.; Zhang, X.; Zhang, Xiaoguang

    2014-12-10

    Measurement of the magnetoresistance (MR) of Au films as a function of temperature and film thickness reveals a strong dependence on grain size distribution and clear violation of the Kohler s rule. Using a model of random resistor network, we show that this result can be explained if the MR arises entirely from inhomogeneity due to grain boundary scattering and thermal activation of grain boundary atoms.

  9. RG flow of the Polyakov-loop potential - first status report

    SciTech Connect (OSTI)

    Braun, J.; Gies, H.; Pirner, H.-J.

    2005-06-14

    We study SU(2) Yang-Mills theory at finite temperature in the framework of the functional renormalization group. We concentrate on the effective potential for the Polyakov loop which serves as an order parameter for confinement. In this first status report, we focus on the behaviour of the effective Polyakov-loop potential at high temperatures. In addition to the standard perturbative result, our findings provide information about the 'RG improved' backreactions of Polyakov-loop fluctuations on the potential. We demonstrate that these fluctuations establish the convexity of the effective potential.

  10. Telescope Guiding with a HyViSI H2RG Used in Guide Mode

    SciTech Connect (OSTI)

    Simms, Lance M.; Figerb, Donald F.; Hanold, Brandon J.; Kahn, Steven M.; Gilmore, D.Kirk

    2010-06-04

    We report on long exposure results obtained with a Teledyne HyViSI H2RG detector operating in guide mode. The sensor simultaneously obtained nearly seeing-limited data while also guiding the Kitt Peak 2.1 m telescope. Results from unguided and guided operation are presented and used to place lower limits on flux/fluence values for accurate centroid measurements. We also report on significant noise reduction obtained in recent laboratory measurements that should further improve guiding capability with higher magnitude stars.

  11. Rationalization of Au concentration and distribution in AuNi...

    Office of Scientific and Technical Information (OSTI)

    Here, using density functional theory, we report the effect of adding Au as the third ... Country of Publication: United States Language: English Subject: 37 INORGANIC, ORGANIC, ...

  12. Recognition of the Activated States of G[alpha]13 by the rgRGS Domain of PDZRhoGEF

    SciTech Connect (OSTI)

    Chen, Zhe; Singer, William D.; Danesh, Shahab M.; Sternweis, Paul C.; Sprang, Stephen R.

    2009-12-01

    G12 class heterotrimeric G proteins stimulate RhoA activation by RGS-RhoGEFs. However, p115RhoGEF is a GTPase Activating Protein (GAP) toward G{alpha}13, whereas PDZRhoGEF is not. We have characterized the interaction between the PDZRhoGEF rgRGS domain (PRG-rgRGS) and the alpha subunit of G13 and have determined crystal structures of their complexes in both the inactive state bound to GDP and the active states bound to GDP {center_dot} AlF (transition state) and GTP{gamma}S (Michaelis complex). PRG-rgRGS interacts extensively with the helical domain and the effector-binding sites on G{alpha}13 through contacts that are largely conserved in all three nucleotide-bound states, although PRG-rgRGS has highest affinity to the Michaelis complex. An acidic motif in the N terminus of PRG-rgRGS occupies the GAP binding site of G{alpha}13 and is flexible in the GDP {center_dot} AlF complex but well ordered in the GTPS complex. Replacement of key residues in this motif with their counterparts in p115RhoGEF confers GAP activity.

  13. COL Application Content Guide for HTGRs: Revision to RG 1.206, Part 1 - Status Report

    SciTech Connect (OSTI)

    Wayne Moe

    2012-08-01

    A combined license (COL) application is required by the Nuclear Regulatory Commission (NRC) for all proposed nuclear plants. The information requirements for a COL application are set forth in 10 CFR 52.79, “Contents of Applications; Technical Information in Final Safety Analysis Report.” An applicant for a modular high temperature gas-cooled reactor (HTGR) must develop and submit for NRC review and approval a COL application which conforms to these requirements. The technical information necessary to allow NRC staff to evaluate a COL application and resolve all safety issues related to a proposed nuclear plant is detailed and comprehensive. To this, Regulatory Guide (RG) 1.206, “Combined License Applications for Nuclear Power Plants” (LWR Edition), was developed to assist light water reactor (LWR) applicants in incorporating and effectively formatting required information for COL application review (Ref. 1). However, the guidance prescribed in RG 1.206 presumes a LWR design proposal consistent with the systems and functions associated with large LWR power plants currently operating under NRC license.

  14. Investigation of structural heterogeneity at the SPE site using combined P–wave travel times and Rg phase velocities

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Rowe, Charlotte A.; Patton, Howard J.

    2015-10-01

    Here, we present analyses of the 2D seismic structure beneath Source Physics Experiments (SPE) geophone lines that extended radially at 100 m spacing from 100 to 2000 m from the source borehole. With seismic sources at only one end of the geophone lines, standard refraction profiling methods cannot resolve seismic velocity structures unambiguously. In previous work, we demonstrated overall agreement between body-wave refraction modeling and Rg dispersion curves for the least complex of the five lines. A more detailed inspection supports a 2D reinterpretation of the structure. We obtained Rg phase velocity measurements in both the time and frequency domains,more » then used iterative adjustment of the initial 1D body-wave model to predict Rg dispersion curves to fit the observed values. Our method applied to the most topographically severe of the geophone lines is supplemented with a 2D ray-tracing approach, whose application to P-wave arrivals supports the Rg analysis. In addition, midline sources will allow us to refine our characterization in future work.« less

  15. https://bluedart.phe.com/owa/?ae=Item&t=IPM.Note&id=RgAAAAA%2f3

    National Nuclear Security Administration (NNSA)

    Phyllis Radack Manager, Regulatory Services 702-295-6582 702-858-5587 (cell) 702-295-7699 ...idRgAAAAA%2f3mOqqZ%2bfSq... 702-858-5587 (cell) 702-295-7699 (fax) From: Morris, Patrick ...

  16. EuTZn (T=Pd, Pt, Au) with TiNiSi-type structure-Magnetic properties and {sup 151}Eu Moessbauer spectroscopy

    SciTech Connect (OSTI)

    Mishra, Trinath; Hermes, Wilfried; Harmening, Thomas; Eul, Matthias; Poettgen, Rainer

    2009-09-15

    The europium compounds EuTZn (T=Pd, Pt, Au) were synthesized from the elements in sealed tantalum tubes in an induction furnace. These intermetallics crystallize with the orthorhombic TiNiSi-type structure, space group Pnma. The structures were investigated by X-ray diffraction on powders and single crystals: a=732.3(2), b=448.5(2), c=787.7(2) pm, R{sub 1}/wR{sub 2}=0.0400/0.0594, 565 F{sup 2} values for EuPdZn, a=727.8(3), b=443.7(1), c=781.7(3) pm, R{sub 1}/wR{sub 2}=0.0605/0.0866, 573 F{sup 2} values for EuPtZn, and a=747.4(2), b=465.8(2), c=789.1(4) pm, R{sub 1}/wR{sub 2}=0.0351/0.0590, 658 F{sup 2} values for EuAuZn, with 20 variables per refinement. Together the T and zinc atoms build up three-dimensional [TZn] networks with short T-Zn distances. The EuTZn compounds show Curie-Weiss behavior in the temperature range from 75 to 300 K with mu{sub eff}=7.97(1), 7.70(1), and 7.94(1) mu{sub B}/Eu atom and theta{sub P}=18.6(1), 34.9(1), and 55.5(1) K for T=Pd, Pt, and Au, respectively, indicating divalent europium. Antiferromagntic ordering was detected at 15.1(3) K for EuPdZn and canted ferromagnetic ordering at 21.2(3) and 51.1(3) K for EuPtZn and EuAuZn. {sup 151}Eu Moessbauer spectroscopic measurements confirm the divalent nature of the europium atoms by isomer shift values ranging from -8.22(8) (EuPtZn) to -9.23(2) mm/s (EuAuZn). At 4.2 K full magnetic hyperfine field splitting is observed in all three compounds due to magnetic ordering of the europium magnetic moments. - Graphical abstract: Europium coordination in EuPdZn, EuPtZn, and EuAuZn.

  17. Ginsenoside-Rg{sub 1} induces angiogenesis by the inverse regulation of MET tyrosine kinase receptor expression through miR-23a

    SciTech Connect (OSTI)

    Kwok, Hoi-Hin; Chan, Lai-Sheung; Poon, Po-Ying; Yue, Patrick Ying-Kit; Wong, Ricky Ngok-Shun

    2015-09-15

    Therapeutic angiogenesis has been implicated in ischemic diseases and wound healing. Ginsenoside-Rg{sub 1} (Rg{sub 1}), one of the most abundant active components of ginseng, has been demonstrated as an angiogenesis-stimulating compound in different models. There is increasing evidence implicating microRNAs (miRNAs), a group of non-coding RNAs, as important regulators of angiogenesis, but the role of microRNAs in Rg{sub 1}-induced angiogenesis has not been fully explored. In this report, we found that stimulating endothelial cells with Rg{sub 1} could reduce miR-23a expression. In silico experiments predicted hepatocyte growth factor receptor (MET), a well-established mediator of angiogenesis, as the target of miR-23a. Transfection of the miR-23a precursor or inhibitor oligonucleotides validated the inverse relationship of miR-23a and MET expression. Luciferase reporter assays further confirmed the interaction between miR-23a and the MET mRNA 3′-UTR. Intriguingly, ginsenoside-Rg{sub 1} was found to increase MET protein expression in a time-dependent manner. We further demonstrated that ginsenoside-Rg{sub 1}-induced angiogenic activities were indeed mediated through the down-regulation of miR-23a and subsequent up-regulation of MET protein expression, as confirmed by gain- and loss-of-function angiogenic experiments. In summary, our results demonstrated that ginsenoside-Rg{sub 1} could induce angiogenesis by the inverse regulation of MET tyrosine kinase receptor expression through miR-23a. This study has broadened our understanding of the non-genomic effects of ginsenoside-Rg{sub 1,} and provided molecular evidence that warrant further development of natural compound as novel angiogenesis-promoting therapy. - Highlights: • Therapeutic angiogenesis has been implicated in ischemic diseases and wound healing. • Ginsenoside-Rg{sub 1} (Rg{sub 1}) has been demonstrated as an angiogenesis-stimulating compound. • We found that Rg{sub 1} induces angiogenesis by

  18. Optical properties of ZnO/ZnS and ZnO/ZnTe heterostructures forphotovoltaic applications

    SciTech Connect (OSTI)

    Schrier, Joshua; Demchenko, Denis O.; Wang, Lin-Wang; Alivisatos,A. Paul

    2007-05-01

    Although ZnO and ZnS are abundant, stable, environmentallybenign, their band gap energies (3.44 eV, 3.72 eV) are too large foroptimal photovoltaic efficiency. By using band-corrected pseudopotentialdensity-functional theory calculations, we study how the band gap,opticalabsorption, and carrier localization canbe controlled by formingquantum-well like and nanowire-based heterostructures ofZnO/ZnS andZnO/ZnTe. In the case of ZnO/ZnS core/shell nanowires, which can besynthesized using existing methods, we obtain a band gap of 2.07 eV,which corresponds to a Shockley-Quiesser efficiency limitof 23 percent.Based on these nanowire results, we propose that ZnO/ZnScore/shellnanowires can be used as photovoltaic devices with organic polymersemiconductors as p-channel contacts.

  19. Global polarization measurement in Au+Au collisions

    SciTech Connect (OSTI)

    Abelev, B.I.; Adams, J.; Aggarwal, M.M.; Ahammed, Z.; Amonett,J.; Anderson, B.D.; Anderson, M.; Arkhipkin, D.; Averichev, G.S.; Bai,Y.; Balewski, J.; Barannikova, O.; Barnby, L.S.; Baudot, J.; Bekele, S.; Belaga, V.V.; Bellingeri-Laurikainen, A.; Bellwied, R.; Benedosso, F.; Bhardwaj, S.; Bhasin, A.; Bhati, A.K.; Bichsel, H.; Bielcik, J.; Bielcikova, J.; Bland, L.C.; Blyth, S.-L.; Bonner, B.E.; Botje, M.; Bouchet, J.; Brandin, A.V.; Bravar, A.; Bystersky, M.; Cadman, R.V.; Cai,X.Z.; Caines, H.; Calderon de la Barca Sanchez, M.; Castillo, J.; Catu,O.; Cebra, D.; Chajecki, Z.; Chaloupka, P.; Chattopadhyay, S.; Chen,H.F.; Chen, J.H.; Cheng, J.; Cherney, M.; Chikanian, A.; Christie, W.; Coffin, J.P.; Cormier, T.M.; Cosentino, M.R.; Cramer, J.G.; Crawford,H.J.; Das, D.; Das, S.; Daugherity, M.; de Moura, M.M.; Dedovich, T.G.; DePhillips, M.; Derevschikov, A.A.; Didenko, L.; Dietel, T.; Djawotho,P.; Dogra, S.M.; Dong, W.J.; Dong, X.; Draper, J.E.; Du, F.; Dunin, V.B.; Dunlop, J.C.; Dutta Mazumdar, M.R.; Eckardt, V.; Edwards, W.R.; Efimov,L.G.; Emelianov, V.; Engelage, J.; Eppley, G.; Erazmus, B.; Estienne, M.; Fachini, P.; Fatemi, R.; Fedorisin, J.; Filimonov, K.; Filip, P.; Finch,E.; Fine, V.; Fisyak, Y.; Fu, J.; Gagliardi, C.A.; Gaillard, L.; Ganti,M.S.; Ghazikhanian, V.; Ghosh, P.; Gonzalez, J.S.; Gorbunov, Y.G.; Gos,H.; Grebenyuk, O.; Grosnick, D.; Guertin, S.M.; Guimaraes, K.S.F.F.; Guo,Y.; Gupta, N.; Gutierrez, T.D.; Haag, B.; Hallman, T.J.; Hamed, A.; Harris, J.W.; He, W.; Heinz, M.; Henry, T.W.; Hepplemann, S.; Hippolyte,B.; Hirsch, A.; Hjort, E.; Hoffman, A.M.; Hoffmann, G.W.; Horner, M.J.; Huang, H.Z.; Huang, S.L.; Hughes, E.W.; Humanic, T.J.; Igo, G.; Jacobs,P.; Jacobs, W.W.; Jakl, P.; Jia, F.; Jiang, H.; Jones, P.G.; Judd, E.G.; Kabana, S.; Kang, K.; Kapitan, J.; Kaplan, M.; Keane, D.; Kechechyan, A.; Khodyrev,V.Yu.; Kim, B.C.; Kiryluk, J.; Kisiel, A.; Kislov, E.M.; Klein,S.R.; Kocoloski, A.; Koetke, D.D.; et al.

    2007-08-02

    The system created in non-central relativisticnucleus-nucleus collisions possesses large orbital angular momentum. Dueto spin-orbit coupling, particles produced in such a system could becomeglobally polarized along the direction of the system angular momentum. Wepresent the results of Lambda and anti-Lambda hyperon global polarizationmeasurements in Au+Au collisions at sqrt sNN=62.4 GeV and 200 GeVperformed with the STAR detector at RHIC. The observed globalpolarization of Lambda and anti-Lambda hyperons in the STAR acceptance isconsistent with zero within the precision of the measurements. Theobtained upper limit, lbar P Lambda, anti-Lambda rbar<= 0.02, iscompared to the theoretical values discussed recently in theliterature.

  20. The electrical and mechanical properties of Au-V and Au-V{sub...

    Office of Scientific and Technical Information (OSTI)

    Journal Article: The electrical and mechanical properties of Au-V and Au-Vsub 2Osub 5 thin films for wear-resistant RF MEMS switches Citation Details In-Document Search Title: ...

  1. Interpretation of the first data on central Au+Au collisions...

    Office of Scientific and Technical Information (OSTI)

    production in central Au+Au collisions taken at RHIC by the PHOBOS Collaboration as well as to existing data on central Pb+Pb collisions taken at the SPS by the NA49 Collaboration. ...

  2. AU Organization Chart | Department of Energy

    Energy Savers [EERE]

    More Documents & Publications AU Functional Area Points of Contact by Office Directors FTCP Senior Technical Safety Manager (STSM) Status Report USW Health Safety and Environment ...

  3. Investigation of structural heterogeneity at the SPE site using combined P–wave travel times and Rg phase velocities

    SciTech Connect (OSTI)

    Rowe, Charlotte A.; Patton, Howard J.

    2015-10-01

    Here, we present analyses of the 2D seismic structure beneath Source Physics Experiments (SPE) geophone lines that extended radially at 100 m spacing from 100 to 2000 m from the source borehole. With seismic sources at only one end of the geophone lines, standard refraction profiling methods cannot resolve seismic velocity structures unambiguously. In previous work, we demonstrated overall agreement between body-wave refraction modeling and Rg dispersion curves for the least complex of the five lines. A more detailed inspection supports a 2D reinterpretation of the structure. We obtained Rg phase velocity measurements in both the time and frequency domains, then used iterative adjustment of the initial 1D body-wave model to predict Rg dispersion curves to fit the observed values. Our method applied to the most topographically severe of the geophone lines is supplemented with a 2D ray-tracing approach, whose application to P-wave arrivals supports the Rg analysis. In addition, midline sources will allow us to refine our characterization in future work.

  4. Graphene-Au Nanoparticles Composite-Based Electrochemical Aptamer...

    Office of Scientific and Technical Information (OSTI)

    Graphene-Au Nanoparticles Composite-Based Electrochemical Aptamer Biosensors Citation Details In-Document Search Title: Graphene-Au Nanoparticles Composite-Based Electrochemical ...

  5. Formation, Migration, and Reactivity of Au CO Complexes on Gold...

    Office of Scientific and Technical Information (OSTI)

    Here, we report experimental as well as theoretical evidence that suggests Au CO complex ... and density functional theory calculations point to Au CO complex formation and migration. ...

  6. Graphene-Au Nanoparticles Composite-Based Electrochemical Aptamer...

    Office of Scientific and Technical Information (OSTI)

    Graphene-Au Nanoparticles Composite-Based Electrochemical Aptamer Biosensors Citation Details In-Document Search Title: Graphene-Au Nanoparticles Composite-Based ...

  7. Au-Pt heteroaggregate dendritic nanostructures and Au-Pt alloy nanoparticles and their use as catalysts

    DOE Patents [OSTI]

    Eichhorn, Bryan W.; Zhou, Shenghu; Jackson, Gregory Scott

    2011-10-18

    Au--Pt heteroaggregate dendritic nanostructures and AuPt alloy nanoparticles, and their use as anodic catalysts in fuel cells.

  8. SrAgZn and EuAgZn with KHg{sub 2}-type structure—Structure, magnetic properties, and {sup 151}Eu Mössbauer spectroscopy

    SciTech Connect (OSTI)

    Gerke, Birgit; Rodewald, Ute Ch.; Niehaus, Oliver; Pöttgen, Rainer

    2013-07-15

    Samples of SrAgZn and EuAgZn were synthesized by reaction of the elements in sealed tantalum crucibles. Both structures were refined on the basis of single crystal X-ray diffractometer data: KHg{sub 2}-type, Imma, a=476.7(1), b=780.9(2), c=810.1(2) pm, R{sub 1}/wR{sub 2}=0.0189/0.0119, 381 F² values for SrAg{sub 1.12}Zn{sub 0.88} and a=474.43(9), b=760.8(2), c=799.0(2) pm, R{sub 1}/wR{sub 2}=0.0226/0.0483, 370 F² values for EuAg{sub 1.17}Zn{sub 0.83} with 13 variables per refinement. Silver and zinc are randomly distributed on the Hg position and build up three-dimensional networks. EuAgZn shows ferromagnetic ordering at 29(1) K. In the temperature range from 75 to 300 K the sample shows Curie–Weiss behaviour with μ{sub eff}=7.87(1) μ{sub B}/Eu atom and θ{sub P}=37.1(1) K, indicating divalent europium. {sup 151}Eu Mössbauer spectroscopic measurements confirmed the divalent state with an isomer shift of −9.31 mm/s at 78 K. Temperature dependent {sup 151}Eu data show first magnetic hyperfine field splitting at 25 K and a saturated magnetization of 17 T at 5.2 K. The temperature dependence can be described by an S=7/2 Brillouin function. - Graphical abstract: The near neighbor coordination of the strontium and europium atoms in SrAg{sub 1.12}Zn{sub 0.88}, EuAg{sub 1.17}Zn{sub 0.83}, and EuAuZn. - Highlights: • Synthesis of new intermetallic zinc compounds SrAgZn and EuAgZn. • Ferromagnetic ordering of EuAgZn at 29 K. • Magnetic hyperfine field splitting in the {sup 151}Eu Mössbauer spectrum.

  9. RHIC Au beam in Run 2014

    SciTech Connect (OSTI)

    Zhang, S. Y.

    2014-09-15

    Au beam at the RHIC ramp in run 2014 is reviewed together with the run 2011 and run 2012. Observed bunch length and longitudinal emittance are compared with the IBS simulations. The IBS growth rate of the longitudinal emittance in run 2014 is similar to run 2011, and both are larger than run 2012. This is explained by the large transverse emittance at high intensity observed in run 2012, but not in run 2014. The big improvement of the AGS ramping in run 2014 might be related to this change. The importance of the injector intensity improvement in run 2014 is emphasized, which gives rise to the initial luminosity improvement of 50% in run 2014, compared with the previous Au-Au run 2011. In addition, a modified IBS model, which is calibrated using the RHIC Au runs from 9.8 GeV/n to 100 GeV/n, is presented and used in the study.

  10. DOElAU62350-43

    Office of Legacy Management (LM)

    DOElAU62350-43 REV. 2 BASELINE RISK ASSESSMENT OF GROUND WATER CONTAMINATION AT THE ... REV. 2 BASELINE RISK ASSESSMENT OF GROUND WATER CONTAMINATION AT THE MONUMENT VALLEY ...

  11. DFT study on cysteine adsorption mechanism on Au(111) and Au(110)

    SciTech Connect (OSTI)

    Buimaga-Iarinca, Luiza; Floare, Calin G.; Calborean, Adrian; Turcu, Ioan

    2013-11-13

    Periodic density functional theory calculations were used to investigate relevant aspects of adsorption mechanisms of cysteine dimers in protonated form on Au(111) and Au(110) surfaces. The projected densities of states are explicitly discussed for all main chemical groups of cysteine, i.e. the amino group (NH2), the thiol group (SH) and the carboxylic group (COOH) to identify differences in adsorption mechanism. Special emphasis is put on the analysis of changes in the electronic structure of molecules adsorbed on Au(111) and Au(110) surfaces as well as the accompanying charge transfer mechanisms at molecule-substrate interaction.

  12. Effect of ZnO facet on ethanol steam reforming over Co/ZnO (Journal...

    Office of Scientific and Technical Information (OSTI)

    Effect of ZnO facet on ethanol steam reforming over CoZnO Citation Details In-Document Search Title: Effect of ZnO facet on ethanol steam reforming over CoZnO The effects of ZnO ...

  13. Jets and dijets in Au+Au and p+p collisions at RHIC

    SciTech Connect (OSTI)

    Hardtke, D.; STAR Collaboration

    2002-12-09

    Recent data from RHIC suggest novel nuclear effects in the production of high p{sub T} hadrons. We present results from the STAR detector on high p{sub T} angular correlations in Au+Au and p+p collisions at {radical}S = 200 GeV/c. These two-particle angular correlation measurements verify the presence of a partonic hard scattering and fragmentation component at high p{sub T} in both central and peripheral Au+Au collisions. When triggering on a leading hadron with p{sub T}>4 GeV, we observe a quantitative agreement between the jet cone properties in p+p and all centralities of Au+Au collisions. This quantitative agreement indicates that nearly all hadrons with p{sub T}>4 GeV/c come from jet fragmentation and that jet fragmentation properties are not substantially modified in Au+Au collisions. STAR has also measured the strength of back-to-back high p{sub T} charged hadron correlations, and observes a small suppression of the back-to-back correlation strength in peripheral collisions, and a nearly complete disappearance o f back-to-back correlations in central Au+Au events. These phenomena, together with the observed strong suppression of inclusive yields and large value of elliptic flow at high p{sub T}, are consistent with a model where high p{sub T} hadrons come from partons created near the surface of the collision region, and where partons that originate or propagate towards the center of the collision region are substantially slowed or completely absorbed.

  14. Synthesis and characterization in AuCu–Si nanostructures

    SciTech Connect (OSTI)

    Novelo, T.E.; Amézaga-Madrid, P.; Maldonado, R.D.; Oliva, A.I.; Alonzo-Medina, G.M.

    2015-03-15

    Au/Cu bilayers with different Au:Cu concentrations (25:75, 50:50 and 75:25 at.%) were deposited on Si(100) substrates by thermal evaporation. The thicknesses of all Au/Cu bilayers were 150 nm. The alloys were prepared by thermal diffusion into a vacuum oven with argon atmosphere at 690 K during 1 h. X-ray diffraction analysis revealed different phases of AuCu and CuSi alloys in the samples after annealing process. CuSi alloys were mainly obtained for 25:75 at.% samples, meanwhile the AuCuII phase dominates for samples prepared with 50:50 at.%. Additionally, the Au:Cu alloys with 75:25 at.%, produce Au{sub 2}Cu{sub 3} and Au{sub 3}Cu phases. The formed alloys were characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM), transmission electron microscopy (TEM) and energy dispersive spectroscopy (EDS) to study the morphology and the elemental concentration of the formed alloys. - Highlights: • AuCu/Si alloy thin films were prepared by thermal diffusion. • Alloys prepared with 50 at.% of Au produce the AuCuII phase. • Alloys prepared with 75 at.% of Au produce Au{sub 3}Cu and Au{sub 2}Cu{sub 3} phases. • All alloys present diffusion of Si and Cu through the CuSi alloy formation.

  15. Rod consolidation of RG and E's (Rochester Gas and Electric Corporation) spent PWR (pressurized water reactor) fuel

    SciTech Connect (OSTI)

    Bailey, W.J.

    1987-05-01

    The rod consolidation demonstration involved pulling the fuel rods from five fuel assemblies from Unit 1 of RG and E's R.E. Ginna Nuclear Power Plant. Slow and careful rod pulling efforts were used for the first and second fuel assemblies. Rod pulling then proceeded smoothly and rapidly after some minor modifications were made to the UST and D consolidation equipment. The compaction ratios attained ranged from 1.85 to 2.00 (rods with collapsed cladding were replaced by dummy rods in one fuel assembly to demonstrate the 2:1 compaction ratio capability). This demonstration involved 895 PWR fuel rods, among which there were some known defective rods (over 50 had collapsed cladding); no rods were broken or dropped during the demonstration. However, one of the rods with collapsed cladding unexplainably broke during handling operations (i.e., reconfiguration in the failed fuel canister), subsequent to the rod consolidation demonstration. The broken rod created no facility problems; the pieces were encapsulated for subsequent storage. Another broken rod was found during postdemonstration cutting operations on the nonfuel-bearing structural components from the five assemblies; evidence indicates it was broken prior to any rod consolidation operations. During the demonstration, burnish-type lines or scratches were visible on the rods that were pulled; however, experience indicates that such lines are generally produced when rods are pulled (or pushed) through the spacer grids. Rods with collapsed cladding would not enter the funnel (the transition device between the fuel assembly and the canister that aids in obtaining high compaction ratios). Reforming of the flattened areas of the cladding on those rods was attempted to make the rod cross sections more nearly circular; some of the reformed rods passed through the funnel and into the canister.

  16. Materials Data on ZnAu3 (SG:64) by Materials Project

    SciTech Connect (OSTI)

    Kristin Persson

    2015-02-09

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  17. Spectral response of nanocrystalline ZnO films embedded with Au nanoparticles

    SciTech Connect (OSTI)

    Patra, Anuradha; Manivannan, A.; Kasiviswanathan, S.

    2012-10-28

    Flame sheet modeling is a common approach for the determination of flame transfer functions for prediction and modeling of thermoacoustic combustion instabilities. The dynamics of the flame-sheet model for simple flame geometries can be shown to be equivalent to a basic model of convective disturbances interacting with a steady heat release region. This framework shows that the flame transfer functions predicted by linearized flame-sheet models are the Fourier transform of the steady heat release rate profile for the flamesheet geometry transformed into Lagrangian convective time reference frame. This result is significant relative to existing flame-sheet modeling approaches in allowing the prediction of dynamic behaviors on the basis of steady information only. Multiple perturbations on the flame can be treated simply via superposition of individual perturbations. Analysis of results from these convective disturbance models illuminates the existence of two independent length scales governing the flame transfer function dynamics. Magnitude is governed by the tip-to-tail length of the flame, whereas phase is governed by the heat release rate profile center of mass calculated from the disturbance origin. The convective disturbance approach shows promise in its potential to derive flame transfer function predictions from a steady flame heat release rate profile.

  18. Materials Data on Zn2CuAu (SG:225) by Materials Project

    SciTech Connect (OSTI)

    Kristin Persson

    2015-01-27

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  19. Suppression of Upsilon production in d + Au and Au + Au collisions at root s(NN) = 200 GeV (vol 735, pg 127, 2014)

    SciTech Connect (OSTI)

    Adamczyk, L.; Adkins, J. K.; Agakishiev, G.; Aggarwal, M. M.; Ahammed, Z.; Alekseev, I.; Alford, J.; Anson, C. D.; Aparin, A.; Arkhipkin, D.; Gliske, S.; Krueger, K.; Spinka, H. M.; Underwood, D.G.

    2014-07-30

    We report measurements of ? meson production in p + p, d +Au, and Au+Aucollisions using the STAR detector at RHIC. We compare the ? yield to the measured cross section in p + p collisions in order to quantify any modifications of the yield in cold nuclear matter using d +Au data and in hot nuclear matter using Au+Au data separated into three centrality classes. Our p +p measurement is based on three times the statistics of our previous result. We obtain a nuclear modification factor for ? (1S + 2S + 3S) in the rapidity range |y| < 1 in d + Aucollisions of RdAu = 0.79 0.24(stat.) 0.03(syst.) 0.10(p + p syst.). A comparison with models including shadowing and initial state parton energy loss indicates the presence of additional cold-nuclear matter suppression. Similarly, in the top 10% most-central Au + Au collisions, we measure a nuclear modification factor of R AA = 0.49 0.1(stat.) 0.02(syst.) 0.06(p + p syst.), which is a larger suppression factor than that seen in cold nuclear matter. Our results are consistent with complete suppression of excited-state ? mesons in Au + Aucollisions. The additional suppression in Au + Au is consistent with the level expected in model calculations that include the presence of a hot, deconfined QuarkGluon Plasma. However, understanding the suppression seen in d + Au is still needed before any definitive statements about the nature of the suppression in Au + Au can be made.

  20. Electronic Structure of Thiol-Covered Gold Nanoparticles: Au102...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Structure of Thiol-Covered Gold Nanoparticles: Au102(MBA)44 Authors: Li, Y., Galli, G., ... properties of thiolate-protected gold nanoparticles Au102(MBA)44 that have ...

  1. Microsoft PowerPoint - Attachment 2 AU Org Chart [Compatibility...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Bill R. McArthur Director AU-12 Office of Worker Safety and Health Assistance Bradley K. Davy Director AU-13 Office of Domestic and International Health Studies Dr. Gerald R. ...

  2. Enhancement of photoluminescence in ZnS/ZnO quantum dots interfacial heterostructures

    SciTech Connect (OSTI)

    Rajalakshmi, M.; Sohila, S.; Ramesh, R.; Bhalerao, G.M.

    2012-09-15

    Highlights: ? ZnS/ZnO quantum dots (QDs) were synthesized by controlled oxidation of ZnS nanoparticles. ? Interfacial heterostructure formation of ZnS/ZnO QDs is seen in HRTEM. ? Enormous enhancement of UV emission (?10 times) in ZnS/ZnO QDs heterostructure is observed. ? Phonon confinement effect is seen in the Raman spectrum. -- Abstract: ZnS/ZnO quantum dots (QDs) were synthesized by controlled oxidation of ZnS nanoparticles. HRTEM image showed small nanocrystals of size 4 nm and the magnified image of single quantum dot shows interfacial heterostructure formation. The optical absorption spectrum shows a blue shift of 0.19 and 0.23 eV for ZnO and ZnS QDs, respectively. This is due to the confinement of charge carries within the nanostructures. Enormous enhancement in UV emission (10 times) is reported which is attributed to interfacial heterostructure formation. Raman spectrum shows phonons of wurtzite ZnS and ZnO. Phonon confinement effect is seen in the Raman spectrum wherein LO phonon peaks of ZnS and ZnO are shifted towards lower wavenumber side and are broadened.

  3. Identified particle distributions in pp and Au+Au collisions atsqrt sNN=200 GeV

    SciTech Connect (OSTI)

    Adams, J.; Adler, C.; Aggarwal, M.M.; Ahammed, Z.; Amonett, J.; Anderson, B.D.; Anderson, M; Arkhipkin, D.; Averichev, G.S.; Badyal,S.K.; Balewski, J.; Barannikova, O.; Barnby, L.S.; Baudot, J.; Bekele,S.; Belaga, V.V.; Bellwied, R.; Berger, J.; Bezverkhny, B.I.; Bhardwaj,S.; Bhaskar, P.; Bhati, A.K.; Bichsel, H.; Billmeier, A.; Bland, L.C.; Blyth, C.O.; Bonner, B.E.; Botje, M.; Boucham, A.; Brandin, A.; Bravar,A.; Cadman, R.V.; Cai, X.Z.; Caines, H.; Calderon de la Barca Sanchez,M.; Carroll, J.; Castillo, J.; Castro, M.; Cebra, D.; Chaloupka, P.; Chattopadhyay, S.; Chen, H.F.; Chen, Y.; Chernenko, S.P.; Cherney, M.; Chikanian, A.; Choi, B.; Christie, W.; Coffin, J.P.; Cormier, T.M.; Cramer, J.G.; Crawford, H.J.; Das, D.; Das, S.; Derevschikov, A.A.; Didenko, L.; Dietel, T.; Dong, X.; Draper, J.E.; Du, F.; Dubey, A.K.; Dunin, V.B.; Dunlop, J.C.; Dutta Majumdar, M.R.; Eckardt, V.; Efimov,L.G.; Emelianov, V.; Engelage, J.; Eppley, G.; Erazmus, B.; Estienne, M.; Fachini, P.; Faine, V.; Faivre, J.; Fatemi, R.; Filimonov, K.; Filip, P.; Finch, E.; Fisyak, Y.; Flierl, D.; Foley, K.J.; Fu, J.; Gagliardi, C.A.; Ganti, M.S.; Gutierrez, T.D.; Gagunashvili, N.; Gans, J.; Gaudichet, L.; Germain, M.; Geurts, F.; Ghazikhanian, V.; Ghosh, P.; Gonzalez, J.E.; Grachov, O.; Grigoriev, V.; Cronstal, S.; Grosnick, D.; Guedon, M.; Guertin, S.M.; Gupta, A.; Gushin, E.; Hallman, T.J.; Hardtke, D.; Harris,J.W.; Heinz, M.; Henry, T.W.; Heppelmann, S.; Herston, T.; Hippolyte, B.; Hirsch, A.; Hjort, E.; Hoffmann, G.W.; Horsley, M.; Huang, H.Z.; Huang,S.L.; Humanic, T.J.; Igo, G.; Ishihara, A.; Jacobs, P.; Jacobs, W.W.; Janik, M.; Johnson, I.; Jones, P.G.; Judd, E.G.; Kabana, S.; Kaneta, M.; Kaplan, M.; Keane, D.; Kiryluk, J.; Kisiel, A.; Klay, J.; Klein, S.R.; Klyachko, A.; Koetke, D.D.; Kollegger, T.; Konstantinov, A.S.; Kopytine,S.M.; Kotchenda, L.; Kovalenko, A.D.; Kramer, M.; Kravtsov, P.; Krueger,K.; Kuhn, C.; Kulikov, A.I.; Kumar, A.; et al.

    2003-10-06

    Transverse mass and rapidity distributions for charged pions, charged kaons, protons and antiprotons are reported for {radical}sNN = 200 GeV pp and Au+Au collisions at RHIC. The transverse mass distributions are rapidity independent within |y| < 0.5, consistent with a boost-invariant system in this rapidity interval. Spectral shapes and relative particle yields are similar in pp and peripheral Au+Au collisions and change smoothly to central Au+Au collisions. No centrality dependence was observed in the kaon and antiproton production rates relative to the pion production rate from medium-central to central collisions. Chemical and kinetic equilibrium model fits to our data reveal strong radial flow and relatively long duration from chemical to kinetic freeze-out in central Au+Au collisions. The chemical freeze-out temperature appears to be independent of initial conditions at RHIC energies.

  4. From the ternary Eu(Au/In)2 and EuAu4(Au/In)2 with remarkable Au/In distributions to a new structure type: The gold-rich Eu5Au16(Au/In)6 structure

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Steinberg, Simon; Card, Nathan; Mudring, Anja -Verena

    2015-08-13

    The ternary Eu(Au/In)2 (EuAu0.46In1.54(2)) (I), EuAu4(Au/In)2 (EuAu4+xIn2–x with x = 0.75(2) (II), 0.93(2), and 1.03(2)), and Eu5Au16(Au/In)6 (Eu5Au17.29In4.71(3)) (III) have been synthesized, and their structures were characterized by single-crystal X-ray diffraction. I and II crystallize with the CeCu2-type (Pearson Symbol oI12; Imma; Z = 4; a = 4.9018(4) Å; b = 7.8237(5) Å; c = 8.4457(5) Å) and the YbAl4Mo2-type (tI14; I4/mmm; Z = 2; a = 7.1612(7) Å; c = 5.5268(7) Å) and exhibit significant Au/In disorder. I is composed of an Au/In-mixed diamond-related host lattice encapsulating Eu atoms, while the structure of II features ribbons of distorted, squaredmore » Au8 prisms enclosing Eu, Au, and In atoms. Combination of these structural motifs leads to a new structure type as observed for Eu5Au16(Au/In)6 (Eu5Au17.29In4.71(3)) (oS108; Cmcm; Z = 4; a = 7.2283(4) Å; b = 9.0499(6) Å; c = 34.619(2) Å), which formally represents a one-dimensional intergrowth of the series EuAu2–“EuAu4In2”. The site preferences of the disordered Au/In positions in II were investigated for different hypothetical “EuAu4(Au/In)2” models using the projector-augmented wave method and indicate that these structures attempt to optimize the frequencies of the heteroatomic Au–In contacts. Furthermore, a chemical bonding analysis on two “EuAu5In” and “EuAu4In2” models employed the TB-LMTO-ASA method and reveals that the subtle interplay between the local atomic environments and the bond energies determines the structural and site preferences for these systems.« less

  5. Synthesis, structure, and bonding in K12Au21Sn4. A polar intermetallic compound with dense Au20 and open AuSn4 layers

    SciTech Connect (OSTI)

    Li, Bin; Kim, Sung-Jin; Miller, Gordon J.; and Corbett, John D.

    2009-10-29

    The new phase K{sub 12}Au{sub 21}Sn{sub 4} has been synthesized by direct reaction of the elements at elevated temperatures. Single crystal X-ray diffraction established its orthorhombic structure, space group Pmmn (No. 59), a = 12.162(2); b = 18.058(4); c = 8.657(2) {angstrom}, V = 1901.3(7) {angstrom}{sup 3}, and Z = 2. The structure consists of infinite puckered sheets of vertex-sharing gold tetrahedra (Au{sub 20}) that are tied together by thin layers of alternating four-bonded-Sn and -Au atoms (AuSn{sub 4}). Remarkably, the dense but electron-poorer blocks of Au tetrahedra coexist with more open and saturated Au-Sn layers, which are fragments of a zinc blende type structure that maximize tetrahedral heteroatomic bonding outside of the network of gold tetrahedra. LMTO band structure calculations reveal metallic properties and a pseudogap at 256 valence electrons per formula unit, only three electrons fewer than in the title compound and at a point at which strong Au-Sn bonding is optimized. Additionally, the tight coordination of the Au framework atoms by K plays an important bonding role: each Au tetrahedra has 10 K neighbors and each K atom has 8-12 Au contacts. The appreciably different role of the p element Sn in this structure from that in the triel members in K{sub 3}Au{sub 5}In and Rb{sub 2}Au{sub 3}Tl appears to arise from its higher electron count which leads to better p-bonding (valence electron concentrations = 1.32 versus 1.22).

  6. Collision-spike sputtering of Au nanoparticles

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Sandoval, Luis; Urbassek, Herbert M.

    2015-08-06

    Ion irradiation of nanoparticles leads to enhanced sputter yields if the nanoparticle size is of the order of the ion penetration depth. While this feature is reasonably well understood for collision-cascade sputtering, we explore it in the regime of collision-spike sputtering using molecular-dynamics simulation. For this specific case of 200-keV Xe bombardment of Au particles, we show that collision spikes lead to abundant sputtering with an average yield of 397 ± 121 atoms compared to only 116 ± 48 atoms for a bulk Au target. Only around 31% of the impact energy remains in the nanoparticles after impact; the remaindermore » is transported away by the transmitted projectile and the ejecta. The sputter yield of supported nanoparticles is estimated to be around 80% of that of free nanoparticles due to the suppression of forward sputtering.« less

  7. Collision-spike sputtering of Au nanoparticles

    SciTech Connect (OSTI)

    Sandoval, Luis; Urbassek, Herbert M.

    2015-08-06

    Ion irradiation of nanoparticles leads to enhanced sputter yields if the nanoparticle size is of the order of the ion penetration depth. While this feature is reasonably well understood for collision-cascade sputtering, we explore it in the regime of collision-spike sputtering using molecular-dynamics simulation. For this specific case of 200-keV Xe bombardment of Au particles, we show that collision spikes lead to abundant sputtering with an average yield of 397 ± 121 atoms compared to only 116 ± 48 atoms for a bulk Au target. Only around 31% of the impact energy remains in the nanoparticles after impact; the remainder is transported away by the transmitted projectile and the ejecta. The sputter yield of supported nanoparticles is estimated to be around 80% of that of free nanoparticles due to the suppression of forward sputtering.

  8. OPERATION OF THE RHIC AU ION SOURCE.

    SciTech Connect (OSTI)

    STESKI,D.B.; ALESSI,J.; BENJAMIN,J.; CARLSON,C.; MANNI,M.; THIEBERGER,P.; WIPLICH,M.

    2001-09-02

    The Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory (BNL) is beginning its second year of operation. A cesium sputter ion source injecting into a tandem Van de Graaff provides the gold ions for RHIC. The ion source is operated in the pulsed beam mode and produces a 500{micro}sec long pulse of Au{sup -} with a peak intensity of 290pA at the entrance of the tandem. After acceleration in the tandem and post stripping, this results in a beam of Au{sup +32} with an intensity of 80e{micro}A and an energy of 182MeV. Over the last several years, a series of improvements have been made to increase the intensity of the pulsed beam from the ion source. Details of the source performance and improvements will be presented. In addition, an effort is under way to provide other beam species for RHIC collisions.

  9. Preparation of new morphological ZnO and Ce-doped ZnO

    SciTech Connect (OSTI)

    Chelouche, A.; Djouadi, D.; Aksas, A.

    2013-12-16

    ZnO micro-tori and cerium doped hexangulars ZnO have been prepared by the sol-gel method under methanol hypercritical conditions of temperature and pressure. X-ray diffraction (XRD) measurement has revealed the high crystalline quality and the nanometric size of the samples. Scanning electron microscopy (SEM) has shown that the ZnO powder has a torus-like shape while that of ZnO:Ce has a hexangular-like shape, either standing free or inserted into the cores of ZnO tori. Transmission electron microscopy (TEM) has revealed that the ZnO particles have sizes between 25 and 30 nm while Ce-doped ZnO grains have diameters ranging from 75 nm to 100 nm. Photoluminescence spectra at room temperature of the samples have revealed that the introduction of cerium in ZnO reduces the emission intensity lines, particularly the ZnO red and green ones.

  10. Ultraviolet emission from a multi-layer graphene/MgZnO/ZnO light-emitting diode

    SciTech Connect (OSTI)

    Kang, Jang-Won; Choi, Yong-Seok; Goo Kang, Chang; Hun Lee, Byoung [School of Materials Science and Engineering, Gwangju Institute of Science and Technology, Gwangju 500-712 (Korea, Republic of); Kim, Byeong-Hyeok [Department of Nanobio Materials and Electronics, Gwangju Institute of Science and Technology, Gwangju 500-712 (Korea, Republic of); Tu, C. W. [Department of Electrical and Computer Engineering, University of California, San Diego, La Jolla, California 92093-0407 (United States); Park, Seong-Ju, E-mail: sjpark@gist.ac.kr [School of Materials Science and Engineering, Gwangju Institute of Science and Technology, Gwangju 500-712 (Korea, Republic of); Department of Nanobio Materials and Electronics, Gwangju Institute of Science and Technology, Gwangju 500-712 (Korea, Republic of)

    2014-02-03

    We report on ultraviolet emission from a multi-layer graphene (MLG)/MgZnO/ZnO light-emitting diodes (LED). The p-type MLG and MgZnO in the MLG/MgZnO/ZnO LED are used as transparent hole injection and electron blocking layers, respectively. The current-voltage characteristics of the MLG/MgZnO/ZnO LED show that current transport is dominated by tunneling processes in the MgZnO barrier layer under forward bias conditions. The holes injected from p-type MLG recombine efficiently with the electrons accumulated in ZnO, and the MLG/MgZnO/ZnO LED shows strong ultraviolet emission from the band edge of ZnO and weak red-orange emission from the deep levels of ZnO.

  11. RHIC performance for FY2011 Au+Au heavy ion run

    SciTech Connect (OSTI)

    Marr, G.; Ahrens, L.; Bai, M.; Beebe-Wang, J.; Blackler, I.; Blaskiewicz, M.; Brennan, J.M.; Brown, K.A.; Bruno, D.; Butler, J.; Carlson, C.; Connolly, R.; D'Ottavio, T.; Drees, K.A.; Fedotov, A.V.; Fischer, W.; Fu, W.; Gardner, C.J.; Gassner, D.M.; Glenn, J.W.; Gu, X.; Harvey, M.; Hayes, T.; Hoff, L.; Huang, H.; Ingrassia, P.F.; Jamilkowski, J.P.; Kling, N.; Lafky, M.; Laster, J.S.; Liu, C.; Luo, Y.; Mapes, M.; Marusic, A.; Mernick, K.; Michnoff, R.J.; Minty, M.G.; Montag, C.; Morris, J.; Naylor, C.; Nemesure, S.; Polizzo, S.; Ptitsyn, V.; Robert-Demolaize, G.; Roser, T.; Sampson, P.; Sandberg, J.; Schoefer, V.; Schultheiss, C.; Severino, F.; Shrey, T.; Smith, K.; Steski, D.; Tepikian, S.; Thieberger, P.; Trbojevic, D.; Tsoupas, N.; Tuozzolo, J.E.; VanKuik, B.; Wang, G.; Wilinski, M.; Zaltsman, A.; Zeno, K.; Zhang, S.Y.

    2011-09-04

    Following the Fiscal Year (FY) 2010 (Run-10) Relativistic Heavy Ion Collider (RHIC) Au+Au run, RHIC experiment upgrades sought to improve detector capabilities. In turn, accelerator improvements were made to improve the luminosity available to the experiments for this run (Run-11). These improvements included: a redesign of the stochastic cooling systems for improved reliability; a relocation of 'common' RF cavities to alleviate intensity limits due to beam loading; and an improved usage of feedback systems to control orbit, tune and coupling during energy ramps as well as while colliding at top energy. We present an overview of changes to the Collider and review the performance of the collider with respect to instantaneous and integrated luminosity goals. At the conclusion of the FY 2011 polarized proton run, preparations for heavy ion run proceeded on April 18, with Au+Au collisions continuing through June 28. Our standard operations at 100 GeV/nucleon beam energy was bracketed by two shorter periods of collisions at lower energies (9.8 and 13.5 GeV/nucleon), continuing a previously established program of low and medium energy runs. Table 1 summarizes our history of heavy ion operations at RHIC.

  12. Laminin receptor specific therapeutic gold nanoparticles (198AuNP...

    Office of Scientific and Technical Information (OSTI)

    prostate cancer Citation Details In-Document Search Title: Laminin receptor specific therapeutic gold nanoparticles (198AuNP-EGCg) show efficacy in treating prostate cancer ...

  13. Microsoft Word - AU Funtional Area Points of Contact by Office...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    (301) 903-3526 AU-30 Headquarters Security Representative Garrett Smith Garrett.Smith@hq.doe.gov (301) 903-7440 Beryllium-Associated Worker Registry Pat Worthington ...

  14. Competition between Order and Phase Separation in Au-Ni

    SciTech Connect (OSTI)

    Reichert, H.; Schoeps, A.; Ramsteiner, I.B.; Bugaev, V.N.; Shchyglo, O.; Udyansky, A.; Dosch, H.; Asta, M.; Drautz, R.; Honkimaeki, V.

    2005-12-02

    We have measured and theoretically analyzed the diffuse scattering in the binary alloy system Au-Ni, which has been proposed as a testing ground for theories of alloy phase stability. We found strong evidence that in the alloys Au{sub 3}Ni and Au{sub 3}Ni{sub 2}, fluctuations of both ordering- and clustering-type are competing with each other. Our results resolve a long-standing controversy on the balance of relaxation and mixing energies in this alloy system and explain recent findings of ordering in thin Au-Ni films.

  15. Preparations for p-Au run in 2015

    SciTech Connect (OSTI)

    Liu, C.

    2014-12-31

    The p-Au particle collision is a unique category of collision runs. This is resulted from the different charge mass ratio of the proton and fully stripped Au ion (1 vs.79/197). The p-Au run requires a special acceleration ramp, and movement of a number of beam components as required by the beam trajectories. The DX magnets will be moved for the first time in the history of RHIC. In this note, the planning and preparations for p-Au run will be presented.

  16. AU Funtional Area Points of Contact by Office Directors - July...

    Office of Environmental Management (EM)

    Listing by AU Office Director 2 FunctionSubject Director Email Phone Commercial membrane classification guidancetechnical support Andrew Weston-Dawkes Andrew.weston-dawkes@h...

  17. Supported bimetallic PdAu nanoparticles with superior electrocatalytic...

    Office of Scientific and Technical Information (OSTI)

    nanoparticles with superior electrocatalytic activity towards methanol oxidation Citation Details In-Document Search Title: Supported bimetallic PdAu nanoparticles with superior ...

  18. ZnS/Zn(O,OH)S-based buffer layer deposition for solar cells

    DOE Patents [OSTI]

    Bhattacharya, Raghu N.

    2009-11-03

    The invention provides CBD ZnS/Zn(O,OH)S and spray deposited ZnS/Zn(O,OH)S buffer layers prepared from a solution of zinc salt, thiourea and ammonium hydroxide dissolved in a non-aqueous/aqueous solvent mixture or in 100% non-aqueous solvent. Non-aqueous solvents useful in the invention include methanol, isopropanol and triethyl-amine. One-step deposition procedures are described for CIS, CIGS and other solar cell devices.

  19. Reflow of AuSnSolder Creates Strong Joints [Local Reflow of AuSn Solder: Relating Strength to Microstructure

    SciTech Connect (OSTI)

    Golosker, Ilya V.; Florando, Jeff N.

    2013-02-01

    Local heating of AuSn solder creates reliable bonds. However, small changes in the heat schedule result in significant changes to bond strength and microstructure.

  20. Piezoelectric and luminescent properties of ZnO nanostructures...

    Office of Scientific and Technical Information (OSTI)

    Conference: Piezoelectric and luminescent properties of ZnO nanostructures on Ag films. Citation Details In-Document Search Title: Piezoelectric and luminescent properties of ZnO ...

  1. High-performance deep ultraviolet photodetectors based on ZnO quantum dot assemblies

    SciTech Connect (OSTI)

    Xu, Xiaoyong; Xu, Chunxiang E-mail: jghu@yzu.edu.cn; Hu, Jingguo E-mail: jghu@yzu.edu.cn

    2014-09-14

    A high-performance ZnO quantum dots (QDs)-based ultraviolet (UV) photodetector has been successfully fabricated via the self-assembly of QDs on the Au interdigital electrode. The broadened band gap in ZnO QDs makes the device has the highly selective response for the deep UV detection. The unique QD-QD junction barriers similar to back-to-back Schottky barriers dominate the conductance of the QD network and the UV light-induced barrier-height modulation plays a crucial role in enhancing the photoresponsivity and the response speed. Typically, the as-fabricated device exhibits the fast response and recovery times of within 1 s, the deep UV selectivity of less than 340 nm, and the stable repeatability with on/off current ratio over 10, photoresponsivity of 5.0410A/W, and photocurrent gain of 1.910, demonstrating that the ZnO QD network is a superior building block for deep UV photodetectors.

  2. Identification of Au–S complexes on Au(100)

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Walen, Holly; Liu, Da -Jiang; Oh, Junepyo; Yang, Hyun Jin; Kim, Yousoo; Thiel, P. A.

    2016-01-25

    In this study, using a combination of scanning tunneling microscopy and density functional theory (DFT) calculations, we have identified a set of related Au–S complexes that form on Au(100), when sulfur adsorbs and lifts the hexagonal surface reconstruction. The predominant complex is diamond-shaped with stoichiometry Au4S5. All of the complexes can be regarded as combinations of S–Au–S subunits. The complexes exist within, or at the edges of, p(2 × 2) sulfur islands that cover the unreconstructed Au regions, and are observed throughout the range of S coverage examined in this study, 0.009 to 0.12 monolayers. A qualitative model is developedmore » which incorporates competitive formation of complexes, Au rafts, and p(2 × 2) sulfur islands, as Au atoms are released by the surface structure transformation.« less

  3. Sideward flow in Au+Au collisions between 2A and 8A GeV

    SciTech Connect (OSTI)

    Liu, H.; Ajitanand, N.N.; Alexander, J.; Anderson, M.; Best, D.; Brady, F.P.; Case, T.; Caskey, W.; Cebra, D.; Chance, J.; Cole, B.; Crowe, K.; Das, A.; Draper, J.; Gilkes, M.; Gushue, S.; Heffner, M.; Hirsch, A.; Hjort, E.; Huo, L.; Justice, M.; Kaplan, M.; Keane, D.; Kintner, J.; Klay, J.; Krofcheck, D.; Lacey, R.; Lisa, M.A.; Liu, Y.M.; McGrath, R.; Milosevich, Z.; Odyniec, G.; Olson, D.; Panitkin, S.Y.; Porile, N.; Rai, G.; Ritter, H.G.; Romero, J.; Scharenberg, R.; Schroeder, L.S.; Srivastava, B.; Stone, N.T.B.; Symons, T.J.M.; Wang, S.; Whitfield, J.; Wienold, T.; Witt, R.; Wood, L.; Yang, X.; Zhang, W.N.; Zhang, Y.; E895 Collaboration

    2000-04-05

    Using the large acceptance Time Projection Chamber of experiment E895 at Brookhaven, measurements of collective sideward flow in Au + Au collisions at beam energies of 2A, 4A, 6A, and 8A GeV are presented in the form of in-plane transverse momentum

  4. Elliptic flow: transition from out-of-plane to in-plane emissionin Au + Au collisions

    SciTech Connect (OSTI)

    Pinkenburg, C.; Ajitanand, N.N.; Alexander, J.M.; Anderson, M.; Best, D.; Brady, F.P.; Case, T.; Caskey, W.; Cebra, D.; Chance, J.L.; Chung, P.; Cole, B.; Crowe, K.; Das, A.C.; Draper, J.E.; Elmaani, A.; Gilkes, M.L.; Gushue, S.; Heffner, M.; Hirsch, A.S.; Hjort, E.L.; Huo,L.; Justice, M.; Kaplan, M.; Keane, D.; Kintner, J.C.; Klay, J.; Krofcheck, D.; Lacey, R.A.; Lauret, J.; Law, C.; Lisa, M.A.; Liu, H.; Liu, Y.M.; McGrath, R.; Milosevich, Z.; Odyniec, G.; Olson, D.L.; Panitkin, S.Y.; Porile, N.T.; Rai, G.; Ritter, H.G.; Romero, J.L.; Scharenberg, R.P.; Schroeder, L.; Srivastava, B.; Stone, N.T.B.; Symons,T.J.M.; Whitfield, J.; Wienold, T.; Witt, R.; Wood, L.; Zhang, W.N.; E895Collaboration; Danielewicz, P.; Gossiaux, P.B.

    1999-07-31

    We have measured the proton elliptic flow excitation function for the Au+Au system spanning the beam energy range (2-8)A GeV. The excitation function shows a transition from negative to positive elliptic flow at a beam energy, Etr {approx} 4A GeV. Detailed comparisons with calculations from a relativistic Boltzmann equation are presented. The comparisons suggest a softening of the nuclear equation of state from a stiff form (K {approx} 380 MeV) at low beam energies (Ebeam < 2A GeV) to a softer form (K {approx} 210 MeV) at higher energies ( Ebeam < 4A GeV) where the calculated baryon density rho {approx} 4 rho 0.

  5. From the ternary Eu(Au/In)2 and EuAu4(Au/In)2 with remarkable Au/In distributions to a new structure type: The gold-rich Eu5Au16(Au/In)6 structure

    SciTech Connect (OSTI)

    Steinberg, Simon; Card, Nathan; Mudring, Anja -Verena

    2015-08-13

    The ternary Eu(Au/In)2 (EuAu0.46In1.54(2)) (I), EuAu4(Au/In)2 (EuAu4+xIn2–x with x = 0.75(2) (II), 0.93(2), and 1.03(2)), and Eu5Au16(Au/In)6 (Eu5Au17.29In4.71(3)) (III) have been synthesized, and their structures were characterized by single-crystal X-ray diffraction. I and II crystallize with the CeCu2-type (Pearson Symbol oI12; Imma; Z = 4; a = 4.9018(4) Å; b = 7.8237(5) Å; c = 8.4457(5) Å) and the YbAl4Mo2-type (tI14; I4/mmm; Z = 2; a = 7.1612(7) Å; c = 5.5268(7) Å) and exhibit significant Au/In disorder. I is composed of an Au/In-mixed diamond-related host lattice encapsulating Eu atoms, while the structure of II features ribbons of distorted, squared Au8 prisms enclosing Eu, Au, and In atoms. Combination of these structural motifs leads to a new structure type as observed for Eu5Au16(Au/In)6 (Eu5Au17.29In4.71(3)) (oS108; Cmcm; Z = 4; a = 7.2283(4) Å; b = 9.0499(6) Å; c = 34.619(2) Å), which formally represents a one-dimensional intergrowth of the series EuAu2–“EuAu4In2”. The site preferences of the disordered Au/In positions in II were investigated for different hypothetical “EuAu4(Au/In)2” models using the projector-augmented wave method and indicate that these structures attempt to optimize the frequencies of the heteroatomic Au–In contacts. Furthermore, a chemical bonding analysis on two “EuAu5In” and “EuAu4In2” models employed the TB-LMTO-ASA method and reveals that the subtle interplay between the local atomic environments and the bond energies determines the structural and site preferences for these systems.

  6. {phi} meson production in Au + Au and p + p collisions at {radical}s{sub NN}=200 GeV

    SciTech Connect (OSTI)

    Adams, J.; Adler, C.; Aggarwal, M.M.; Ahammed, Z.; Amonett, J.; Anderson, B.D.; Arkhipkin, D.; Averichev, G.S.; Badyal, S.K.; Balewski, J.; Barannikova, O.; Barnby, L.S.; Baudot, J.; Bekele, S.; Belaga, V.V.; Bellwied, R.; Berger, J.; Bezverkhny, B.I.; Bhardwaj, S.; Bhati, A.K.; Bichsel, H.; Billmeier, A.; Bland, L.C.; Blyth, C.O.; Bonner, B.E.; Botje, M.; Boucham, A.; Brandin, A.; Bravar, A.; Cadman, R.V.; Cai, X.Z.; Caines, H.; Calderon de la Barca Sanchez, M.; Carroll, J.; Castillo, J.; Cebra, D.; Chaloupka, P.; Chattopadhyay, S.; Chen, H.F.; Chen, Y.; Chernenko, S.P.; Cherney, M.; Chikanian, A.; Christie, W.; Coffin, J.P.; Cormier, T.M.; Cramer, J.G.; Crawford, H.J.; Das, D.; Das, S.; Derevschikov, A.A.; Didenko, L.; Dietel, T.; Dong, W.J.; Dong, X.; Draper, J.E.; Du, F.; Dubey, A.K.; Dunin, V.B.; Dunlop, J.C.; Dutta Majumdar, M.R.; Eckardt, V.; Efimov, L.G.; Emelianov, V.; Engelage, J.; Eppley, G.; Erazmus, B.; Estienne, M.; Fachini, P.; Faine, V.; Faivre, J.; Fatemi, R.; Filimonov, K.; Filip, P.; Finch, E.; Fisyak, Y.; Flierl, D.; Foley, K.J.; Fu, J.; Gagliardi, C.A.; Gagunashvili, N.; Gans, J.; Ganti, M.S.; Gaudichet, L.; Germain, M.; Geurts, F.; Ghazikhanian, V.; Ghosh, P.; Gonzalez, J.E.; Grachov, O.; Grebenyuk, O.; Gronstal, S.; Grosnick, D.; Guedon, M.; Guertin, S.M.; Gupta, A.; Gutierrez, T.D.; Hallman, T.J.; Hamed, A.; Hardtke, D.; Harris, J.W.; Heinz, M.; Henry, T.W.; Heppelmann, S.; Hippolyte, B.; Hirsch, A.; Hjort, E.; Hoffmann, G.W.; Horsley, M.; Huang, H.Z.; Huang, S.L.; Hughes, E.; Humanic, T.J.; Igo, G.; Ishihara, A.; Jacobs, P.; Jacobs, W.W.; Janik, M.; Johnson, I.; Jones, P.G.; Judd, E.G.; Kabana, S.; Kaplan, M.; Keane, D.; Khodyrev; Kiryluk, J.; Kisiel, A.; Klay, J.; Klein, S.R.; Klyachko, A.; Koetke, D.D.; Kollegger, T.; Kopytine, S.M.; Kotchenda, L.; Kovalenko, A.D.; Kramer, M.; Kravtsov, P.; Kravstov, V.I.; Krueger, K.; Kuhn, C.; Kulikov, A.I.; Kumar, A.; Kunde, G.J.; Kunz, C.L.; Kutuev, R.Kh.; et al.

    2004-06-01

    We report the STAR measurement of {psi} meson production in Au + Au and p + p collisions at {radical}s{sub NN} = 200 GeV. Using the event mixing technique, the {psi} spectra and yields are obtained at midrapidity for five centrality bins in Au+Au collisions and for non-singly-diffractive p+p collisions. It is found that the {psi} transverse momentum distributions from Au+Au collisions are better fitted with a single-exponential while the p+p spectrum is better described by a double-exponential distribution. The measured nuclear modification factors indicate that {psi} production in central Au+Au collisions is suppressed relative to peripheral collisions when scaled by the number of binary collisions (). The systematics of versus centrality and the constant {psi}/K{sup -} ratio versus beam species, centrality, and collision energy rule out kaon coalescence as the dominant mechanism for {psi} production.

  7. CO Oxidation mechanism on CeO2-supported Au nanoclusters

    SciTech Connect (OSTI)

    Kim H. Y.; Henkelman, G.

    2013-09-08

    To reveal the richer chemistry of CO oxidation by CeO2 supported Au Nanoclusters(NCs)/Nanoparticles, we design Au13 and Au12 supported on a flat and a stepped-CeO2 model (Au/CeO2) and study various kinds of CO oxidation mechanisms at the Au-CeO2 interface and the Au NC as well.

  8. Observation of D0 meson nuclear modifications in Au+Au collisions at sNN=200 GeV

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Adamczyk, L.; Adkins, J. K.; Agakishiev, G.; Aggarwal, M. M.; Ahammed, Z.; Alekseev, I.; Alford, J.; Anson, C. D.; Aparin, A.; Arkhipkin, D.; et al

    2014-09-30

    We report the first measurement of charmed-hadron (D0) production via the hadronic decay channel (D0→K-+π+) in Au+Au collisions at √sNN=200 GeV with the STAR experiment. The charm production cross section per nucleon-nucleon collision at midrapidity scales with the number of binary collisions, Nbin, from p+p to central Au+Au collisions. The D0 meson yields in central Au+Aucollisions are strongly suppressed compared to those in p+p scaled by Nbin, for transverse momenta pT>3 GeV/c, demonstrating significant energy loss of charm quarks in the hot and dense medium. An enhancement at intermediate pT is also observed. Model calculations including strong charm-medium interactions andmore »coalescence hadronization describe our measurements.« less

  9. Observation of D0 meson nuclear modifications in Au+Au collisions at sNN=200 GeV

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Adamczyk, L.; Adkins, J. K.; Agakishiev, G.; Aggarwal, M. M.; Ahammed, Z.; Alekseev, I.; Alford, J.; Anson, C. D.; Aparin, A.; Arkhipkin, D.; et al

    2014-09-30

    We report the first measurement of charmed-hadron (D0) production via the hadronic decay channel (D0→K-+π+) in Au+Au collisions at √sNN=200 GeV with the STAR experiment. The charm production cross section per nucleon-nucleon collision at midrapidity scales with the number of binary collisions, Nbin, from p+p to central Au+Au collisions. The D0 meson yields in central Au+Aucollisions are strongly suppressed compared to those in p+p scaled by Nbin, for transverse momenta pT>3 GeV/c, demonstrating significant energy loss of charm quarks in the hot and dense medium. An enhancement at intermediate pT is also observed. Model calculations including strong charm-medium interactions andmore » coalescence hadronization describe our measurements.« less

  10. Au plasmonics in a WS{sub 2}-Au-CuInS{sub 2} photocatalyst for significantly enhanced hydrogen generation

    SciTech Connect (OSTI)

    Cheng, Zhongzhou; Wang, Zhenxing E-mail: hej@nanoctr.cn; Shifa, Tofik Ahmed; Wang, Fengmei; Zhan, Xueying; Xu, Kai; He, Jun E-mail: hej@nanoctr.cn; Liu, Quanlin

    2015-11-30

    Promoting the activities of photocatalysts is still the critical challenge in H{sub 2} generation area. Here, a Au plasmon enhanced photocatalyst of WS{sub 2}-Au-CuInS{sub 2} is developed by inserting Au nanoparticles between WS{sub 2} nanotubes and CuInS{sub 2} (CIS) nanoparticles. Due to the localized surface plasmonic resonance properties from Au nanoparticles, WS{sub 2}-Au-CIS shows the best performance as compared to Au-CIS, CIS, WS{sub 2}-CIS, CIS-Au, WS{sub 2}-Au, and WS{sub 2}-CIS-Au. The surface plasmonic resonance effects dramatically intensify the absorption of visible light and help to inject hot electrons into the semiconductors. Our findings open up an efficient method to optimize the type-II structures for photocatalytic water splitting.

  11. Corrigendum to Suppression of ? production in d+Au and Au+Au collisions at ? SNN = 200 GeV" [Phys. Lett. B 735 (2014) 127-137

    SciTech Connect (OSTI)

    Adamczyk, L.

    2015-04-01

    We report measurements of ? meson production in p + p, d + Au, and Au+Au collisions using the STAR detector at RHIC. We compare the ? yield to the measured cross section in p + p collisions in order to quantify any modifications of the yield in cold nuclear matter using d + Au data and in hot nuclear matter using Au+Au data separated into three centrality classes. Our p + p measurement is based on three times the statistics of our previous result. We obtain a nuclear modification factor for Upsilon (1S + 2S + 3S) in the rapidity range |y| < 1 in d + Au collisions of RdAu = 0.79 0.24(stat.) 0.03(syst.) 0.10(p + p syst.). A comparison with models including shadowing and initial state parton energy loss indicates the presence of additional cold-nuclear matter suppression. Similarly, in the top 10% most-central Au + Au collisions, we measure a nuclear modification factor of R AA = 0.49 0.1(stat.) 0.02(syst.) 0.06(p + p syst.), which is a larger suppression factor than that seen in cold nuclear matter. Our results are consistent with complete suppression of excited-state Upsilon mesons in Au + Au collisions. The additional suppression in Au + Au is consistent with the level expected in model calculations that include the presence of a hot, deconfined QuarkGluon Plasma. However, understanding the suppression seen in d + Au is still needed before any definitive statements about the nature of the suppression in Au + Au can be made.

  12. Corrigendum to “Suppression of Υ production in d+Au and Au+Au collisions at √ SNN = 200 GeV" [Phys. Lett. B 735 (2014) 127-137

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Adamczyk, L.

    2015-04-01

    We report measurements of Υ meson production in p + p, d + Au, and Au+Au collisions using the STAR detector at RHIC. We compare the Υ yield to the measured cross section in p + p collisions in order to quantify any modifications of the yield in cold nuclear matter using d + Au data and in hot nuclear matter using Au+Au data separated into three centrality classes. Our p + p measurement is based on three times the statistics of our previous result. We obtain a nuclear modification factor for Upsilon (1S + 2S + 3S) in themore » rapidity range |y| < 1 in d + Au collisions of RdAu = 0.79 ± 0.24(stat.) ± 0.03(syst.) ± 0.10(p + p syst.). A comparison with models including shadowing and initial state parton energy loss indicates the presence of additional cold-nuclear matter suppression. Similarly, in the top 10% most-central Au + Au collisions, we measure a nuclear modification factor of R AA = 0.49 ±0.1(stat.) ±0.02(syst.) ±0.06(p + p syst.), which is a larger suppression factor than that seen in cold nuclear matter. Our results are consistent with complete suppression of excited-state Upsilon mesons in Au + Au collisions. The additional suppression in Au + Au is consistent with the level expected in model calculations that include the presence of a hot, deconfined Quark–Gluon Plasma. However, understanding the suppression seen in d + Au is still needed before any definitive statements about the nature of the suppression in Au + Au can be made.« less

  13. An electrostatic nanogenerator based on ZnO/ZnS core/shell electrets with stabilized quasi-permanent charge

    SciTech Connect (OSTI)

    Wang, Chao; Cai, Liang; Feng, Yajuan; Chen, Lin; Yan, Wensheng E-mail: zhsun@ustc.edu.cn; Liu, Qinghua; Yao, Tao; Hu, Fengchun; Pan, Zhiyun; Sun, Zhihu E-mail: zhsun@ustc.edu.cn; Wei, Shiqiang

    2014-06-16

    ZnO-based nanogenerators with excellent performance and convenient functionalization are particularly desirable for self-powered technology, which is however difficult to achieve simultaneously in traditional piezoelectric ZnO nanogenerators. Here, we report a design of electrostatic ZnO nanogenerator by virtue of a type-II ZnO/ZnS core/shell nanostructure electrets, which can turn acoustic waves into electric power with an energy conversion efficiency of 2.2%. The ZnO/ZnS core/shell electrets are charged by ultraviolet irradiation with a long-term stability of the electrostatic charges under ambient condition. The electronic and atomic structure evolution in the charged ZnO/ZnS core/shell electrets are also discussed by detailed experimental and theoretical investigations. This design opens up an alternative path for fabricating robust ZnO-based nanogenerator for future nanotechnology application.

  14. Graphene-Au Nanoparticles Composite-Based Electrochemical Aptamer

    Office of Scientific and Technical Information (OSTI)

    Biosensors (Conference) | SciTech Connect Conference: Graphene-Au Nanoparticles Composite-Based Electrochemical Aptamer Biosensors Citation Details In-Document Search Title: Graphene-Au Nanoparticles Composite-Based Electrochemical Aptamer Biosensors Authors: Guo, Shaojun [1] + Show Author Affiliations Los Alamos National Laboratory Publication Date: 2014-03-27 OSTI Identifier: 1126641 Report Number(s): LA-UR-13-28234 DOE Contract Number: AC52-06NA25396 Resource Type: Conference Resource

  15. Corrigendum to “Suppression of Υ production in d+Au and Au+Au collisions at √ SNN = 200 GeV" [Phys. Lett. B 735 (2014) 127-137

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Adamczyk, L.

    2015-04-01

    We report measurements of Υ meson production in p + p, d + Au, and Au+Au collisions using the STAR detector at RHIC. We compare the Υ yield to the measured cross section in p + p collisions in order to quantify any modifications of the yield in cold nuclear matter using d + Au data and in hot nuclear matter using Au+Au data separated into three centrality classes. Our p + p measurement is based on three times the statistics of our previous result. We obtain a nuclear modification factor for Upsilon (1S + 2S + 3S) in themore »rapidity range |y| dAu = 0.79 ± 0.24(stat.) ± 0.03(syst.) ± 0.10(p + p syst.). A comparison with models including shadowing and initial state parton energy loss indicates the presence of additional cold-nuclear matter suppression. Similarly, in the top 10% most-central Au + Au collisions, we measure a nuclear modification factor of R AA = 0.49 ±0.1(stat.) ±0.02(syst.) ±0.06(p + p syst.), which is a larger suppression factor than that seen in cold nuclear matter. Our results are consistent with complete suppression of excited-state Upsilon mesons in Au + Au collisions. The additional suppression in Au + Au is consistent with the level expected in model calculations that include the presence of a hot, deconfined Quark–Gluon Plasma. However, understanding the suppression seen in d + Au is still needed before any definitive statements about the nature of the suppression in Au + Au can be made.« less

  16. Study of asymmetries of Cd(Zn)Te devices investigated using photo-induced current transient spectroscopy, Rutherford backscattering, surface photo-voltage spectroscopy, and gamma ray spectroscopies

    SciTech Connect (OSTI)

    Crocco, J.; Bensalah, H.; Zheng, Q.; Dieguez, E.; Corregidor, V.; Avles, E.; Castaldini, A.; Fraboni, B.; Cavalcoli, D.; Cavallini, A.; Vela, O.

    2012-10-01

    Despite these recent advancements in preparing the surface of Cd(Zn)Te devices for detector applications, large asymmetries in the electronic properties of planar Cd(Zn)Te detectors are common. Furthermore, for the development of patterned electrode geometries, selection of each electrode surface is crucial for minimizing dark current in the device. This investigation presented here has been carried out with three objectives. Each objective is oriented towards establishing reliable methods for the selection of the anode and cathode surfaces independent of the crystallographic orientation. The objectives of this study are (i) investigate how the asymmetry in I-V characteristics of Cd(Zn)Te devices may be associated with the TeO2 interfacial layer using Rutherford backscattering to study the structure at the Au-Cd(Zn)Te interface, (ii) develop an understanding of how the concentration of the active traps in Cd(Zn)Te varies with the external bias, and (iii) propose non-destructive methods for selection of the anode and cathode which are independent of crystallographic orientation. The spectroscopic methods employed in this investigation include Rutherford backscattering spectroscopy, photo-induced current transient spectroscopy, and surface photo-voltage spectroscopy, as well as gamma ray spectroscopy to demonstrate the influence on detector properties.

  17. RHIC PERFORMANCE DURING THE FY10 200 GeV Au+Au HEAVY ION RUN

    SciTech Connect (OSTI)

    Brown, K.A.; Ahrens, L.; Bai, M.; Beebe-Wang, J.; Blaskiewicz, M.; Brennan, J.; Bruno, D.; Carlson, C.; Connolly, R.; de Maria, R.; DOttavio, T.; Drees, A.; Fischer, W.; Fu, W.; Gardner, C.; Gassner, D.; Glenn, J.W.; Hao, Y.; Harvey, M.; Hayes, T.; Hoff, L.; Huang, H.; Laster, J.; Lee, R.; Litvinenko, V.; Luo, Y.; MacKay, W.; Marr, G.; Marusic, A.; Mernick, K.; Michnoff, R.; Minty, M.; Montag, C.; Morris, J.; Nemesure, S.; Oerter, B.; Pilat, F.; Ptitsyn, V.; Robert-Demolaize, G.; Roser, T.; Russo, T.; Sampson, P.; Sandberg, J.; Satogata, T.; Severino, F.; Schoefer, V.; Schultheiss, C.; Smith, K.; Steski, D.; Tepikian, S.; Theisen, C.; Thieberger, P.; Trbojevic, D.; Tsoupas, N.; Tuozzolo, J.; Wang, G.; Wilinski, M.; Zaltsman, A.; Zeno, K.; Zhang, S.Y.

    2010-05-23

    Since the last successful RHIC Au+Au run in 2007 (Run-7), the RHIC experiments have made numerous detector improvements and upgrades. In order to benefit from the enhanced detector capabilities and to increase the yield of rare events in the acquired heavy ion data a significant increase in luminosity is essential. In Run-7 RHIC achieved an average store luminosity of = 12 x 10{sup 26} cm{sup -2} s{sup -1} by operating with 103 bunches (out of 111 possible), and by squeezing to {beta}* = 0.85 m. This year, Run-10, we achieved = 20 x 10{sup 26} cm{sup -2} s{sup -1}, which put us an order of magnitude above the RHIC design luminosity. To reach these luminosity levels we decreased {beta}* to 0.75 m, operated with 111 bunches per ring, and reduced longitudinal and transverse emittances by means of bunched-beam stochastic cooling. In addition we introduced a lattice to suppress intra-beam scattering (IBS) in both RHIC rings, upgraded the RF control system, and separated transition crossing times in the two rings. We present an overview of the changes and the results of Run-10 performance.

  18. Azimuthal anisotophy in U + U and Au + Au collisions at RHIC

    SciTech Connect (OSTI)

    Adamczyk, L.

    2015-11-24

    Collisions between prolate uranium nuclei are used to study how particle production and azimuthal anisotropies depend on initial geometry in heavy-ion collisions. We report the two- and four-particle cumulants, v2{2} and v2{4}, for charged hadrons from U+U collisions at √SNN = 193 GeV and Au+Au collisions at √SNN = 200 GeV. Nearly fully overlapping collisions are selected based on the energy deposited by spectators in zero degree calorimeters (ZDCs). Within this sample, the observed dependence of v2{2} on multiplicity demonstrates that ZDC information combined with multiplicity can preferentially select different overlap configurations in U+U collisions. As a result, we also show that v2 vs multiplicity can be better described by models, such as gluon saturation or quark participant models, that eliminate the dependence of the multiplicity on the number of binary nucleon-nucleon collisions.

  19. Azimuthal anisotophy in U + U and Au + Au collisions at RHIC

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Adamczyk, L.

    2015-11-24

    Collisions between prolate uranium nuclei are used to study how particle production and azimuthal anisotropies depend on initial geometry in heavy-ion collisions. We report the two- and four-particle cumulants, v2{2} and v2{4}, for charged hadrons from U+U collisions at √SNN = 193 GeV and Au+Au collisions at √SNN = 200 GeV. Nearly fully overlapping collisions are selected based on the energy deposited by spectators in zero degree calorimeters (ZDCs). Within this sample, the observed dependence of v2{2} on multiplicity demonstrates that ZDC information combined with multiplicity can preferentially select different overlap configurations in U+U collisions. As a result, we alsomore » show that v2 vs multiplicity can be better described by models, such as gluon saturation or quark participant models, that eliminate the dependence of the multiplicity on the number of binary nucleon-nucleon collisions.« less

  20. Measurement of J/? Azimuthal Anisotropy in Au+Au Collisions at ?sNN=200 GeV

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Adamczyk, L.; Adkins, J. K.; Agakishiev, G.; Aggarwal, M. M.; Ahammed, Z.; Alekseev, I.; Alford, J.; Anson, C. D.; Aparin, A.; Arkhipkin, D.; et al

    2013-08-02

    The measurement of J/? azimuthal anisotropy is presented as a function of transverse momentum for different centralities in Au+Au collisions at ?sNN>/sub>=200 GeV. The measured J/? elliptic flow is consistent with zero within errors for transverse momentum between 2 and 10 GeV/c. Our measurement suggests that J/? particles with relatively large transverse momenta are not dominantly produced by coalescence from thermalized charm quarks, when comparing to model calculations.

  1. Azimuthally sensitive hanbury brown-twiss interferometry in Au + Au collisions sqrt S sub NN = 200 GeV

    SciTech Connect (OSTI)

    Adams, J.; Adler, C.; Aggarwal, M.M.; Ahammed, Z.; Amonett, J.; Anderson, B.D.; Arkhipkin, D.; Averichev, G.S.; Badyal, S.K.; Balewski, J.; Barannikova, O.; Barnby, L.S.; Baudot, J.; Bekele, S.; Belaga, V.V.; Bellwied, R.; Berger, J.; Bezverkhny, B.I.; Bhardwaj, S.; Bhati, A.K.; Bichsel, H.; Billmeier, A.; Bland, L.C.; Blyth, C.O.; Bonner, B.E.; Botje, M.; Boucham, A.; Brandin, A.; Bravar, A.; Cadman, R.V.; Cai, X.Z.; Caines, H.; Calderon de la Barca Sanchez, M.; Carroll, J.; Castillo, J.; Cebra, D.; Chaloupka, P.; Chattopadhyay, S.; Chen, H.F.; Chen, Y.; Chernenko, S.P.; Cherney, M.; Chikanian, A.; Christie, W.; Coffin, J.P.; Cormier, T.M.; Cramer, J.G.; Crawford, H.J.; Das, D.; Das, S.; Derevschikov, A.A.; Didenko, L.; Dietel, T.; Dong, W.J.; Dong, X.; Draper, J.E.; Du, F.; Dubey, A.K.; Dunin, V.B.; Dunlop, J.C.; Dutta Majumdar, M.R.; Eckardt, V.; Efimov, L.G.; Emelianov, V.; Engelage, J.; Eppley, G.; Erazmus, B.; Estienne, M.; Fachini, P.; Faine, V.; Faivre, J.; Fatemi, R.; Filimonov, K.; Filip, P.; Finch, E.; Fisyak, Y.; Flierl, D.; Foley, K.J.; Fu, J.; Gagliardi, C.A.; Gagunashvili, N.; Gans, J.; Gaudichet, L.; Geurts, F.; Ghazikhanian, V.; Ghosh, P.; Gonzalez, J.E.; Grachov, O.; Grebenyuk, O.; Gronstal, S.; Grosnick, D.; Guertin, S.M.; Gupta, A.; Gutierrez, T.D.; Hallman, T.J.; Hamed, A.; Hardtke, D.; Harris, J.W.; Heinz, M.; Henry, T.W.; Heppelmann, S.; Hippolyte, B.; Hirsch, A.; Hjort, E.; Hoffmann, G.W.; Horsley, M.; Huang, H.Z.; Huang, L.S.; Hughes, E.; Humanic, T.J.; Igo, G.; Ishihara, A.; Jacobs, P.; Jacobs, W.W.; Janik, M.; Jiang, H.; Johnson, I.; Jones, P.G.; Judd, E.G.; Kabana, S.; Kaplan, M.; Keane, D.; Khodyrev, V.Yu.; Kiryluk, J.; Kisiel, A.; Klay, J.; Klein, S.R.; Klyachko, A.; Koetke, D.D.; Kollegger, T.; Kopytine, M.; Kotchenda, L.; Kovalenko, A.D.; Kramer, M.; Kravtsov, V.I.; Kravtsov, P.; Krueger, K.; Kuhn, C.; Kulikov, A.I.; Kumar, A.; Kunde, G.J.; Kunz, C.L.; Kutuev, R.Kh.; Kuznetsov, A.A.; Lamont, M.A.C.; et al.

    2004-06-30

    We present the results of a systematic study of the shape of the pion distribution in coordinate space at freeze-out in Au+Au collisions at RHIC using two-pion Hanbury Brown-Twiss (HBT) interferometry. Oscillations of the extracted HBT radii vs. emission angle indicate sources elongated perpendicular to the reaction plane. The results indicate that the pressure and expansion time of the collision system are not sufficient to completely quench its initial shape.

  2. Disappearance of back-to-back high p {sub T} hadron correlations in central Au+Au collisions at {radical}s{sub NN} = 200 GeV

    SciTech Connect (OSTI)

    Adler, C.; Ahammed, Z.; Allgower, C.; Amonett, J.; Anderson, B.D.; Anderson, M.; Averichev, G.S.; Balewski, J.; Barannikova, O.; Barnby, L.S.; Baudot, J.; Bekele, S.; Belaga, V.V.; Bellwied, R.; Berger, J.; Bichsel, H.; Billmeier, A.; Bland, L.C.; Blyth, C.O.; Bonner, B.E.; Boucham, A.; Brandin, A.; Bravar, A.; Cadman, R.V.; Caines, H.; Calderon de la Barca Sanchez, M.; Cardenas, A.; Carroll, J.; Castillo, J.; Castro, M.; Cebra, D.; Chaloupka, P.; Chattopadhyay, S.; Chen, Y.; Chernenko, S.P.; Cherney, M.; Chikanian, A.; Choi, B.; Christie, W.; Coffin, J.P.; Cormier, T.M.; Corral, M.M.; Cramer, J.G.; Crawford, H.J.; Derevschikov, A.A.; Didenko, L.; Dietel, T.; Draper, J.E.; Dunin, V.B.; Dunlop, J.C.; Eckardt, V.; Efimov, L.G.; Emelianov, V.; Engelage, J.; Eppley, G.; Erazmus, B.; Fachini, P.; Faine, V.; Faivre, J.; Fatemi, R.; Filimonov, K.; Finch, E.; Fisyak, Y.; Flierl, D.; Foley, K.J.; Fu, J.; Gagliardi, C.A.; Gagunashvili, N.; Gans, J.; Gaudichet, L.; Germain, M.; Geurts, F.; Ghazikhanian, V.; Grachov, O.; Grigoriev, V.; Guedon, M.; Gushin, E.; Hallman, T.J.; Hardtke, D.; Harris, J.W.; Henry, T.W.; Heppelmann, S.; Herston, T.; Hippolyte, B.; Hirsch, A.; Hjort, E.; Hoffmann, G.W.; Horsley, M.; Huang, H.Z.; Humanic, T.J.; Igo, G.J.; Ishihara, A.; Ivanshin, Yu.I.; Jacobs, P.; Jacobs, W.W.; Janik, M.; Johnson, I.; Jones, P.G.; Judd, E.G.; Kaneta, M.; Kaplan, M.; Keane, D.; Kiryluk, J.; Kisiel, A.; Klay, J.; Klein, S.R.; Klyachko, A.; Kollegger, T.; Konstantinov, A.S.; Kopytine, M.; Kotchenda, L.; Kovalenko, A.D.; Kramer, M.; Kravtsov, P.; Krueger, K.; Kuhn, C.; Kulikov, A.I.; Kunde, G.J.; Kunz, C.L.; Kutuev, R.Kh.; Kuznetsov, A.A.; Lakehal-Ayat, L.; Lamont, M.A.C.; Landgraf, J.M.; Lange, S.; Lansdell, C.P.; Lasiuk, B.; Laue, F.; Lauret, J.; Lebedev, A.; Lednicky, R.; Leontiev, V.M.; LeVine, M.J.; Li , Q.; Lindenbaum, S.J.; Lisa, M.A.; Liu, F.; Liu, L.; Liu, Z.; Liu, Q.J.; Ljubicic, T.; Llope, W.J.; LoCurto, G.; et al.

    2002-10-25

    Azimuthal correlations for large transverse momentum charged hadrons have been measured over a wide pseudo-rapidity range and full azimuth in Au+Au and p+p collisions at = {radical}s{sub NN} = 200 GeV. The small-angle correlations observed in p+p collisions and at all centralities of Au+Au collisions are characteristic of hard-scattering processes already observed in elementary collisions. A strong back-to-back correlation exists for p+p and peripheral Au + Au. In contrast, the back-to-back correlations are reduced considerably in the most central Au+Au collisions, indicating substantial interaction as the hard-scattered partons or their fragmentation products traverse the medium.

  3. Rationalization of Au concentration and distribution in AuNi@Pt core-shell nanoparticles for oxygen reduction reaction

    SciTech Connect (OSTI)

    An, Wei; Liu, Ping

    2015-09-18

    Improving the activity and stability of Pt-based coreshell nanocatalysts for proton exchange membrane fuel cells while lowering Pt loading has been one of the big challenges in electrocatalysis. Here, using density functional theory, we report the effect of adding Au as the third element to enhance the durability and activity of Ni@Pt coreshell nanoparticles (NPs) during the oxygen reduction reaction (ORR). Our results show that the durability and activity of a Ni@Pt NP can be finely tuned by controlling Au concentration and distribution. For a NiAu@Pt NP, the durability can be greatly promoted by thermodynamically favorable segregation of Au to replace the Pt atoms at vertex, edge, and (100) facets on the shell, while still keeping the ORR activity on the active Pt(111) shell as high as that of Ni@Pt nanoparticles. Such behavior strongly depends on a direct interaction with the Ni interlayer. The results not only highlight the importance of interplay between surface strain on the shell and the interlayershell interaction in determining the durability and activity but also provide guidance on how to maximize the usage of Au to optimize the performance of coreshell (Pt) nanoparticles. As a result, such understanding has allowed us to discover a novel NiAu@Pt nanocatalyst for the ORR.

  4. Rationalization of Au concentration and distribution in AuNi@Pt core-shell nanoparticles for oxygen reduction reaction

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    An, Wei; Liu, Ping

    2015-09-18

    Improving the activity and stability of Pt-based core–shell nanocatalysts for proton exchange membrane fuel cells while lowering Pt loading has been one of the big challenges in electrocatalysis. Here, using density functional theory, we report the effect of adding Au as the third element to enhance the durability and activity of Ni@Pt core–shell nanoparticles (NPs) during the oxygen reduction reaction (ORR). Our results show that the durability and activity of a Ni@Pt NP can be finely tuned by controlling Au concentration and distribution. For a NiAu@Pt NP, the durability can be greatly promoted by thermodynamically favorable segregation of Au tomore » replace the Pt atoms at vertex, edge, and (100) facets on the shell, while still keeping the ORR activity on the active Pt(111) shell as high as that of Ni@Pt nanoparticles. Such behavior strongly depends on a direct interaction with the Ni interlayer. The results not only highlight the importance of interplay between surface strain on the shell and the interlayer–shell interaction in determining the durability and activity but also provide guidance on how to maximize the usage of Au to optimize the performance of core–shell (Pt) nanoparticles. As a result, such understanding has allowed us to discover a novel NiAu@Pt nanocatalyst for the ORR.« less

  5. Heterojunction metal-oxide-metal Au-Fe{sub 3}O{sub 4}-Au single nanowire device for spintronics

    SciTech Connect (OSTI)

    Reddy, K. M. Punnoose, Alex; Hanna, Charles; Padture, Nitin P.

    2015-05-07

    In this report, we present the synthesis of heterojunction magnetite nanowires in alumina template and describe magnetic and electrical properties from a single nanowire device for spintronics applications. Heterojunction Au-Fe-Au nanowire arrays were electrodeposited in porous aluminum oxide templates, and an extensive and controlled heat treatment process converted Fe segment to nanocrystalline cubic magnetite phase with well-defined Au-Fe{sub 3}O{sub 4} interfaces as confirmed by the transmission electron microscopy. Magnetic measurements revealed Verwey transition shoulder around 120 K and a room temperature coercive field of 90 Oe. Current–voltage (I-V) characteristics of a single Au-Fe{sub 3}O{sub 4}-Au nanowire have exhibited Ohmic behavior. Anomalous positive magnetoresistance of about 0.5% is observed on a single nanowire, which is attributed to the high spin polarization in nanowire device with pure Fe{sub 3}O{sub 4} phase and nanocontact barrier. This work demonstrates the ability to preserve the pristine Fe{sub 3}O{sub 4} and well defined electrode contact metal (Au)–magnetite interface, which helps in attaining high spin polarized current.

  6. ZnCuInS/ZnSe/ZnS Quantum Dot-Based Downconversion Light-Emitting Diodes and Their Thermal Effect

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Liu, Wenyan; Zhang, Yu; Ruan, Cheng; Wang, Dan; Zhang, Tieqiang; Feng, Yi; Gao, Wenzhu; Yin, Jingzhi; Wang, Yiding; Riley, Alexis P.; et al

    2015-01-01

    The quantum dot-based light-emitting diodes (QD-LEDs) were fabricated using blue GaN chips and red-, yellow-, and green-emitting ZnCuInS/ZnSe/ZnS QDs. The power efficiencies were measured as 14.0 lm/W for red, 47.1 lm/W for yellow, and 62.4 lm/W for green LEDs at 2.6 V. The temperature effect of ZnCuInS/ZnSe/ZnS QDs on these LEDs was investigated using CIE chromaticity coordinates, spectral wavelength, full width at half maximum (FWHM), and power efficiency (PE). The thermal quenching induced by the increased surface temperature of the device was confirmed to be one of the important factors to decrease power efficiencies while the CIE chromaticity coordinates changed little due to themore » low emission temperature coefficients of 0.022, 0.050, and 0.068 nm/°C for red-, yellow-, and green-emitting ZnCuInS/ZnSe/ZnS QDs. These indicate that ZnCuInS/ZnSe/ZnS QDs are more suitable for downconversion LEDs compared to CdSe QDs.« less

  7. ZnO and MgZnO Nanocrystalline Flexible Films: Optical and Material Properties

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Huso, Jesse; Morrison, John L.; Che, Hui; Sundararajan, Jency P.; Yeh, Wei Jiang; McIlroy, David; Williams, Thomas J.; Bergman, Leah

    2011-01-01

    An emore » merging material for flexible UV applications is Mg x Zn 1 − x O which is capable of tunable bandgap and luminescence in the UV range of ~3.4 eV–7.4 eV depending on the composition x . Studies on the optical and material characteristics of ZnO and Mg 0.3 Zn 0.7 O nanocrystalline flexible films are presented. The analysis indicates that the ZnO and Mg 0.3 Zn 0.7 O have bandgaps of 3.34 eV and 4.02 eV, respectively. The photoluminescence (PL) of the ZnO film was found to exhibit a structural defect-related emission at ~3.316 eV inherent to the nanocrystalline morphology. The PL of the Mg 0.3 Zn 0.7 O film exhibits two broad peaks at 3.38 eV and at 3.95 eV that are discussed in terms of the solubility limit of the ZnO-MgO alloy system. Additionally, external deformation of the film did not have a significant impact on its properties as indicated by the Raman LO-mode behavior, making these films attractive for UV flexible applications.« less

  8. Formation, Migration, and Reactivity of Au CO Complexes on Gold Surfaces

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Wang, Jun; McEntee, Monica; Tang, Wenjie; Neurock, Matthew; Baddorf, Arthur P.; Maksymovych, Petro; Yates, Jr, John T.

    2016-01-12

    Here, we report experimental as well as theoretical evidence that suggests Au CO complex formation upon the exposure of CO to active sites (step edges and threading dislocations) on a Au(111) surface. Room-temperature scanning tunneling microscopy (STM), X-ray photoelectron spectroscopy, transmission infrared spectroscopy, and density functional theory calculations point to Au CO complex formation and migration. Room-temperature STM of the Au(111) surface at CO pressures in the range from 10^ 8 to 10^ 4 Torr (dosage up to 10^6 langmuir) indicates Au atom extraction from dislocation sites of the herringbone reconstruction, mobile Au CO complex formation and diffusion, and Aumore » adatom cluster formation on both elbows and step edges on the Au surface. The formation and mobility of the Au CO complex result from the reduced Au Au bonding at elbows and step edges leading to stronger Au CO bonding and to the formation of a more positively charged CO (CO +) on Au. These studies indicate that the mobile Au CO complex is involved in the Au nanoparticle formation and reactivity, and that the positive charge on CO increases due to the stronger adsorption of CO at Au sites with lower coordination numbers.« less

  9. Homoepitaxy of ZnO and MgZnO Films at 90 C

    SciTech Connect (OSTI)

    Ehrentraut, Dirk; Goh, Gregory K.L.; Fujii, Katsushi; Ooi, Chin Chun; Quang, Le Hong; Fukuda, Tsuguo; Kano, Masataka; Zhang, Yuantao; Matsuoka, Takashi

    2014-06-01

    The aqueous synthesis of uniform single crystalline homoepitaxial zinc oxide, ZnO, and magnesium zinc oxide, Mg{sub x}Zn{sub 1?x}O, films under very low temperature conditions at T=90 C and ambient pressure has been explored. A maximum Mg content of 1 mol% was recorded by energy dispersive spectroscopy. The growth on the polar (0 0 0 1) and (0 0 0 1) faces resulted in films that are strongly different in their structural and optical quality as evidenced by high-resolution X-ray diffraction, secondary electron microscopy, and photoluminescence. This is a result of the chemistry and temperature of the solution dictating the stability range of growth-governing metastable species. The use of trisodium citrate, Na{sub 3}C{sub 6}H{sub 5}O{sub 7}, yielded coalesced, mirror-like homoepitaxial films whereas adding magnesium nitrate hexahydrate, Mg(NO{sub 3}){sub 2}6H{sub 2}O, favors the growth of films with pronounced faceting. - Graphical abstract: Homoepitaxial ZnO films grown from aqueous solution below boiling point of water on a ZnO substrate with off-orientation reveal parallel grooves that are characterized by (1 0 1{sup } 1) facets. Adding trisodium citrate yields closed, single-crystalline ZnO films, which can further be functionalized. Alloying with MgO yields MgZnO films with low Mg content only. - Highlights: A simple method to synthesize uniform single crystalline homoepitaxial ZnO and MgZnO films. ZnO growth on (0 0 0 1) and (0 0 0 1{sup }) face resulted in films that are strongly different in their structural and optical quality. Single crystalline MgZnO film was fabricated under mild conditions (90 C and ambient pressure). Mg incorporation of nearly 1 mol% was obtained while maintaining single phase wurtzite structure.

  10. Cyclotron production of {sup 61}Cu using natural Zn and enriched {sup 64}Zn targets

    SciTech Connect (OSTI)

    Asad, A. H.; Smith, S. V.; Chan, S.; Jeffery, C. M.; Morandeau, L.; Price, R. I.

    2012-12-19

    Copper-61 ({sup 61}Cu) shares with {sup 64}Cu certain advantages for PET diagnostic imaging, but has a shorter half-life (3.4hr vs. 12.7hr) and a greater probability of positron production per disintegration (61% vs. 17.9%). One important application is for in vivo imaging of hypoxic tissue. In this study {sup 61}Cu was produced using the {sup 64}Zn(p,{alpha}){sup 61}Cu reaction on natural Zn or enriched {sup 64}Zn targets. The enriched {sup 64}Zn (99.82%) was electroplated onto high purity gold or silver foils or onto thin Al discs. A typical target bombardment used 30{mu}A; at 11.7, 14.5 or 17.6MeV over 30-60min. The {sup 61}Cu (radiochemical purity of >95%) was separated using a combination of cation and anion exchange columns. The {sup 64}Zn target material was recovered after each run, for re-use. In a direct comparison with enriched {sup 64}Zn-target results, {sup 61}Cu production using the cheaper {sup nat}Zn target proved to be an effective alternative.

  11. Final Technical Report: First Principles Investigations for the Ensemble Effects of PdAu and PtAu Bimetallic Nanocatalysts

    SciTech Connect (OSTI)

    Ruqian Wu

    2012-05-18

    Bimetallic surfaces with tunable chemical properties have attracted broad attention in recent years due to their ample potential for heterogeneous catalysis applications. The local chemical properties of constituents are strongly altered from their parent metals by 'ligand effect', a term encompassing the influences of charge transfer, orbital rehybridization and lattice strain. In comparison to the aforementioned, the 'ensemble effect' associated with particular arrangements of the active constituents have received much less attention, despite their notable importance towards the determination of reactivity and selectivity of bimetallic catalysts. We performed theoretical studies for understanding the ensemble effects on bimetallic catalysis: (i) simulations for the formation of different ensembles on PdAu and PtAu nanoclusters; (ii) studies of the size, shape, and substrate dependence of their electronic properties; and (iii) simulations for model reactions such as CO oxidation, methanol, ethylene and water dehydrogenation on PdAu and PtAu nanoclusters. In close collaboration with leading experimental groups, our theoretical research elucidated the fundamentals of Au based bimetallic nanocatalysts.

  12. Atomic Structure of Au329(SR)84 Faradaurate Plasmonic Nanomolecules

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Kumara, Chanaka; Zuo, Xiaobing; Ilavsky, Jan; Cullen, David; Dass, Amala

    2015-04-03

    To design novel nanomaterials, it is important to precisely control the composition, determine the atomic structure, and manipulate the structure to tune the materials property. Here we present a comprehensive characterization of the material whose composition is Au329(SR)84 precisely, therefore referred to as a nanomolecule. The size homogeneity was shown by electron microscopy, solution X-ray scattering, and mass spectrometry. We proposed its atomic structure to contain the Au260 core using experiments and modeling of a total-scattering-based atomic-pair distribution functional analysis. HAADF-STEM images shows fcc-like 2.0 ± 0.1 nm diameter nanomolecules.

  13. Graphene nanoribbons synthesized from molecular precursor polymerization on Au(110)

    SciTech Connect (OSTI)

    Massimi, Lorenzo; Ourdjini, Oualid; Della Pia, Ada; Mariani, Carlo; Betti, Maria Grazia; Cavaliere, Emanuele; Gavioli, Luca

    2015-06-23

    A spectroscopic study of 10,10-dibromo-9,9 bianthracene (DBBA) molecules deposited on the Au(110) surface is presented, by means of ultraviolet and X-ray photoemission, and X-ray absorption spectroscopy. Through a thermally activated procedure, these molecular precursors polymerize and eventually form graphene nanoribbons (GNRs) with atomically controlled shape and width, very important building blocks for several technological applications. The GNRs observed by scanning tunneling microscopy (STM) appear as short segments on top of the gold surface reconstruction, pointing out the delicate balance among surface diffusion and surface corrugation in their synthesis on the Au(110) surface.

  14. Electroluminescence of ZnO-based semiconductor heterostructures

    SciTech Connect (OSTI)

    Novodvorskii, O A; Lotin, A A; Panchenko, Vladislav Ya; Parshina, L S; Khaidukov, E V; Zuev, D A; Khramova, O D [Institute on Laser and Information Technologies, Russian Academy of Sciences, Shatura, Moscow Region (Russian Federation)

    2011-01-31

    Using pulsed laser deposition, we have grown n-ZnO/p-GaN, n-ZnO/i-ZnO/p-GaN and n-ZnO/n-Mg{sub 0.2}Zn{sub 0.8}O/i-Cd{sub 0.2}Zn{sub 0.8}O/p-GaN light-emitting diode (LED) heterostructures with peak emission wavelengths of 495, 382 and 465 nm and threshold current densities (used in electroluminescence measurements) of 1.35, 2, and 0.48 A cm{sup -2}, respectively. Because of the spatial carrier confinement, the n-ZnO/n-Mg{sub 0.2}Zn{sub 0.8}O/i-Cd{sub 0.2}Zn{sub 0.8}O/p-GaN double heterostructure LED offers a higher electroluminescence intensity and lower electroluminescence threshold in comparison with the n-ZnO/p-GaN and n-ZnO/i-ZnO/p-GaN LEDs. (lasers)

  15. Formation of Zn-rich phyllosilicate, Zn-layered double hydroxide and hydrozincite in contaminated calcareous soils

    SciTech Connect (OSTI)

    Jacquat, Olivier; Voegelin, Andreas; Villard, Andre; Marcus, Matthew A.; Kretzschmar, Ruben

    2007-10-15

    Recent studies demonstrated that Zn-phyllosilicate- and Zn-layered double hydroxide-type (Zn-LDH) precipitates may form in contaminated soils. However, the influence of soil properties and Zn content on the quantity and type of precipitate forming has not been studied in detail so far. In this work, we determined the speciation of Zn in six carbonate-rich surface soils (pH 6.2 to 7.5) contaminated by aqueous Zn in the runoff from galvanized power line towers (1322 to 30090 mg/kg Zn). Based on 12 bulk and 23 microfocused extended X-ray absorption fine structure (EXAFS) spectra, the number, type and proportion of Zn species were derived using principal component analysis, target testing, and linear combination fitting. Nearly pure Zn-rich phyllosilicate and Zn-LDH were identified at different locations within a single soil horizon, suggesting that the local availabilities of Al and Si controlled the type of precipitate forming. Hydrozincite was identified on the surfaces of limestone particles that were not in direct contact with the soil clay matrix. With increasing Zn loading of the soils, the percentage of precipitated Zn increased from {approx}20% to {approx}80%, while the precipitate type shifted from Zn-phyllosilicate and/or Zn-LDH at the lowest studied soil Zn contents over predominantly Zn-LDH at intermediate loadings to hydrozincite in extremely contaminated soils. These trends were in agreement with the solubility of Zn in equilibrium with these phases. Sequential extractions showed that large fractions of soil Zn ({approx}30% to {approx}80%) as well as of synthetic Zn-kerolite, Zn-LDH, and hydrozincite spiked into uncontaminated soil were readily extracted by 1 M NH{sub 4}NO{sub 3} followed by 1 M NH{sub 4}-acetate at pH 6.0. Even though the formation of Zn precipitates allows for the retention of Zn in excess to the adsorption capacity of calcareous soils, the long-term immobilization potential of these precipitates is limited.

  16. Preparation, structural and optical characterization of ZnO, ZnO: Al nanopowder

    SciTech Connect (OSTI)

    Mohan, R. Raj; Rajendran, K.; Sambath, K.

    2014-01-28

    In this paper, ZnO and ZnO:Al nanopowders have been synthesized by low cost hydrothermal method. Zinc nitrate, hexamethylenetetramine (HMT) and aluminium nitrate are used as precursors for ZnO and AZO with different molar ratios. The structural and optical characterization of doped and un-doped ZnO powders have been investigated by X-ray diffraction (XRD), Scanning electron microscopy (SEM), Energy dispersive X-ray spectroscopy (EDAX), photoluminescence (PL) and ultra violet visible (UV-Vis) absorption studies. The SEM results show that the hydrothermal synthesis can be used to obtain nanoparticles with different morphology. It is observed that the grain size of the AZO nanoparticles increased with increasing of Al concentration. The PL measurement of AZO shows that broad range of green emission around 550nm with high intensity. The green emission resulted mainly because of intrinsic defects.

  17. Low frequency noise in the unstable contact region of Au-to-Au microcontact for microelectromechanical system switches

    SciTech Connect (OSTI)

    Qiu, Haodong; Wang, Hong; Ke, Feixiang

    2014-06-23

    The noise behavior of Au-to-Au microcontact for microelectromechanical system switches has been experimentally studied in the unstable contact region. The results suggest that the electrical conduction remains nonmetallic at the initial stage during contact formation due to the existence of alien films, and traps in the alien layer located at the contact interface could play an important role in determining the conduction noise. The conduction fluctuation induced by electron trapping-detrapping associated with the hydrocarbon layer is found to be an intrinsic noise source contributing to the low frequency noise in the unstable contact region.

  18. Dielectron Azimuthal Anisotropy at mid-rapidity in Au+Au collisions at root s=200GeV

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Adamczyk, L.

    2014-12-11

    We report on the first measurement of the azimuthal anisotropy (v₂) of dielectrons (e⁺e⁻ pairs) at mid-rapidity from √(sNN)=200 GeV Au + Au collisions with the STAR detector at the Relativistic Heavy Ion Collider (RHIC), presented as a function of transverse momentum (pT) for different invariant-mass regions. In the mass region Meeee<2.9GeV/c², the measured dielectron v₂ is consistent, within experimental uncertainties, with that from the cc¯ contributions.

  19. ΛΛ correlation function in Au + Au collisions at √sNN = 200 GeV

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Adamczyk, L.

    2015-01-12

    In this study, we present ΛΛ correlation measurements in heavy-ion collisions for Au+Au collisions at √sNN = 200 GeV using the STAR experiment at the Relativistic Heavy-Ion Collider (RHIC). The Lednický-Lyuboshitz analytical model has been used to fit the data to obtain a source size, a scattering length and an effective range. Implications of the measurement of the ΛΛ correlation function and interaction parameters for di-hyperon searches are discussed.

  20. Improvements in Modeling Au Sphere Non-LTE X-ray Emission (Conference...

    Office of Scientific and Technical Information (OSTI)

    Improvements in Modeling Au Sphere Non-LTE X-ray Emission Citation Details In-Document Search Title: Improvements in Modeling Au Sphere Non-LTE X-ray Emission We've previously ...

  1. Gold-rich R3Au7Sn3: Establishing the interdependence between...

    Office of Scientific and Technical Information (OSTI)

    Gold-rich R3Au7Sn3: Establishing the interdependence between electronic features and physical properties Citation Details In-Document Search Title: Gold-rich R3Au7Sn3: Establishing ...

  2. AuRu/AC as an effective catalyst for hydrogenation reactions

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Villa, Alberto; Chan-Thaw, Carine E.; Campisi, Sebastiano; Bianchi, Claudia L.; Wang, Di; Kotula, Paul G.; Kübel, Christian; Prati, Laura

    2015-03-23

    AuRu bimetallic catalysts have been prepared by sequential deposition of Au on Ru or vice versa obtaining different nanostructures: when Ru has been deposited on Au, a Aucore–Rushell has been observed, whereas the deposition of Au on Ru leads to a bimetallic phase with Ru enrichment on the surface. In the latter case, the unexpected Ru enrichment could be attributed to the weak adhesion of Ru on the carbon support, thus allowing Ru particles to diffuse on Au particles. Both structures result very active in catalysing the liquid phase hydrogenolysis of glycerol and levulinic acid but the activity, the selectivitymore » and the stability depend on the structure of the bimetallic nanoparticles. Ru@Au/AC core–shell structure mostly behaved as the monometallic Ru, whereas the presence of bimetallic AuRu phase in Au@Ru/AC provides a great beneficial effect on both activity and stability.« less

  3. Twinning effect on photoluminescence spectra of ZnSe nanowires

    SciTech Connect (OSTI)

    Xu, Jing; Wang, Chunrui Wu, Binhe; Xu, Xiaofeng; Chen, Xiaoshuang; Oh, Hongseok; Baek, Hyeonjun; Yi, Gyu-Chul

    2014-11-07

    Bandgap engineering in a single material along the axial length of nanowires may be realized by arranging periodic twinning, whose twin plane is vertical to the axial length of nanowires. In this paper, we report the effect of twin on photoluminescence of ZnSe nanowires, which refers to the bandgap of it. The exciton-related emission peaks of transverse twinning ZnSe nanowires manifest a 10-meV-blue-shift in comparison with those of longitudinal twinning ZnSe nanowires. The blue-shift is attributed to quantum confinement effect, which is influenced severely by the proportion of wurtzite ZnSe layers in ZnSe nanowires.

  4. Observation of dynamic water microadsorption on Au surface

    SciTech Connect (OSTI)

    Huang, Xiaokang, E-mail: xiaokang.huang@tqs.com; Gupta, Gaurav; Gao, Weixiang; Tran, Van; Nguyen, Bang; McCormick, Eric; Cui, Yongjie; Yang, Yinbao; Hall, Craig; Isom, Harold [TriQuint Semiconductor, Inc., 500 W Renner Road, Richardson, Texas 75080 (United States)

    2014-05-15

    Experimental and theoretical research on water wettability, adsorption, and condensation on solid surfaces has been ongoing for many decades because of the availability of new materials, new detection and measurement techniques, novel applications, and different scales of dimensions. Au is a metal of special interest because it is chemically inert, has a high surface energy, is highly conductive, and has a relatively high melting point. It has wide applications in semiconductor integrated circuitry, microelectromechanical systems, microfluidics, biochips, jewelry, coinage, and even dental restoration. Therefore, its surface condition, wettability, wear resistance, lubrication, and friction attract a lot of attention from both scientists and engineers. In this paper, the authors experimentally investigated Au{sub 2}O{sub 3} growth, wettability, roughness, and adsorption utilizing atomic force microscopy, scanning electron microscopy, reflectance spectrometry, and contact angle measurement. Samples were made using a GaAs substrate. Utilizing a super-hydrophilic Au surface and the proper surface conditions of the surrounding GaAs, dynamic microadsorption of water on the Au surface was observed in a clean room environment. The Au surface area can be as small as 12??m{sup 2}. The adsorbed water was collected by the GaAs groove structure and then redistributed around the structure. A model was developed to qualitatively describe the dynamic microadsorption process. The effective adsorption rate was estimated by modeling and experimental data. Devices for moisture collection and a liquid channel can be made by properly arranging the wettabilities or contact angles of different materials. These novel devices will be very useful in microfluid applications or biochips.

  5. Growth of Long Range Forward-Backward Multiplicity Correlations with Centrality in Au+Au Collisions at sqrt sNN = 200 GeV

    SciTech Connect (OSTI)

    STAR Collaboration; Abelev, Betty

    2010-07-05

    Forward-backward multiplicity correlation strengths have been measured with the STAR detector for Au+Au and p+p collisions at {radical}s{sub NN} = 200 GeV. Strong short and long range correlations (LRC) are seen in central Au+Au collisions. The magnitude of these correlations decrease with decreasing centrality until only short range correlations are observed in peripheral Au+Au collisions. Both the Dual Parton Model (DPM) and the Color Glass Condensate (CGC) predict the existence of the long range correlations. In the DPM the fluctuation in the number of elementary (parton) inelastic collisions produces the LRC. In the CGC longitudinal color flux tubes generate the LRC. The data is in qualitative agreement with the predictions from the DPM and indicates the presence of multiple parton interactions.

  6. Impact of air-exposure on the chemical and electronic structure ofZnO:Zn3N2 thin films

    SciTech Connect (OSTI)

    Bar, M.; Ahn, K.-S.; Shet, S.; Yan, Y.; Weinhardt, L.; Fuchs, O.; Blum, M.; Pookpanratana, S.; George, K.; Yang, W.; Denlinger, J.D.; Al-Jassim, M.; Heske, C.

    2008-09-08

    The chemical and electronic surface structure of ZnO:Zn3N2 ("ZnO:N") thin films with different N contents was investigated by soft x-ray emission spectroscopy. Upon exposure to ambient air (in contrast to storage in vacuum), the chemical and electronic surface structure of the ZnO:N films changes substantially. In particular, we find that the Zn3N2/(Zn3N2+ZnO) ratio decreases with exposure time and that this change depends on the initial N content. We suggest a degradation mechanism based on the reaction of the Zn3N2 content with atmospheric humidity.

  7. The growth of sulfur adlayers on Au(100)

    SciTech Connect (OSTI)

    Jiang, Yue; Ren, Shendong; Chen, Chi-Lu; Liang, Xihui; Fan, Liang-Jen; Yang, Yaw-Wen; Tang, Jian-Ming; Luh, Dah-An

    2015-02-14

    We have studied the growth of S layers adsorbed on Au(100) with low-energy electron diffraction (LEED), X-ray photoemission spectra (XPS), and scanning tunneling microscope (STM). Three phases of S/Au(100)—(2 × 2), trimer, and c(2 × 4)—are identified; the latter two are not previously reported. A dose of S{sub 2} at 300 K transformed Au(100)-(5 × 20) initially into the (2 × 2) phase and formed the c(2 × 4) phase at a saturation coverage. The STM results show that monolayer Au islands formed during the initial S dose and remained throughout the growth, resulting in a rough c(2 × 4) surface. We show that a highly ordered c(2 × 4) phase can be obtained with a flat (2 × 2) phase as an intermediate step during growth. Based on the evolution of XPS and STM images with varied S{sub 2} dose, the components of S 2p are assigned and structural models for the various S/Au(100) phases are proposed. In the (2 × 2) phase, one S atom resides on a four-fold hollow site in each (2 × 2) unit cell, corresponding to a S coverage of 0.25 ML; in the trimer phase, three S atoms form a trimer residing on a four-fold hollow site in each (2 × 2) unit cell, corresponding to a S coverage of 0.75 ML; in the c(2 × 4) phase, there are five S atoms in each primitive unit cell of c(2 × 4); three of them form a trimer residing on a four-fold hollow site, and the other two form a dimer located on the top of the trimer, corresponding to a nominal S coverage of 1.25 ML. With the proposed structural models, the growth of S on Au(100) at 300 K is described in detail.

  8. Transverse momentum and centrality dependence of high-ptnon-photonic electron suppression in Au+Au collisions at $\\sqrt{s_{NN}}$= 200 GeV

    SciTech Connect (OSTI)

    Abelev, B.I.; Adams, J.; Aggarwal, M.M.; Ahammed, Z.; Amonett,J.; Anderson, B.D.; Anderson, M.; Arkhipkin, D.; Averichev, G.S.; Bai,Y.; Balewski, J.; Barannikova, O.; Barnby, L.S.; Baudot, J.; Bekele, S.; Belaga, V.V.; Bellingeri-Laurikainen, A.; Bellwied, R.; Benedosso, F.; Bhardwaj, S.; Bhasin, A.; Bhati, A.K.; Bichsel, H.; Bielcik, J.; Bielcikova, J.; Bland, L.C.; Blyth, S.-L.; Bonner, B.E.; Botje, M.; Bouchet, J.; Brandin, A.V.; Bravar, A.; Bystersky, M.; Cadman, R.V.; Cai,X.Z.; Caines, H.; Calderon de la Barca Sanchez, M.; Castillo, J.; Catu,O.; Cebra, D.; Chajecki, Z.; Chaloupka, P.; Chattopadhyay, S.; Chen,H.F.; Chen, J.H.; Cheng, J.; Cherney, M.; Chikanian, A.; Christie, W.; Coffin, J.P.; Cormier, T.M.; Cosentino, M.R.; Cramer, J.G.; Crawford,H.J.; Das, D.; Das, S.; Daugherity, M.; de Moura, M.M.; Dedovich, T.G.; DePhillips, M.; Derevschikov, A.A.; Didenko, L.; Dietel, T.; Djawotho,P.; Dogra, S.M.; Dong, W.J.; Dong, X.; Draper, J.E.; Du, F.; Dunin, V.B.; Dunlop, J.C.; Dutta Mazumdar, M.R.; Eckardt, V.; Edwards, W.R.; Efimov,L.G.; Emelianov, V.; Engelage, J.; Eppley, G.; Erazmus, B.; Estienne, M.; Fachini, P.; Fatemi, R.; Fedorisin, J.; Filimonov, K.; Filip, P.; Finch,E.; Fine, V.; Fisyak, Y.; Fu, J.; Gagliardi, C.A.; Gaillard, L.; Ganti,M.S.; Ghazikhanian, V.; Ghosh, P.; Gonzalez, J.S.; Gorbunov, Y.G.; Gos,H.; Grebenyuk, O.; Grosnick, D.; Guertin, S.M.; Guimaraes, K.S.F.F.; Guo,Y.; Gupta, N.; Gutierrez, T.D.; Haag, B.; Hallman, T.J.; Hamed, A.; Harris, J.W.; He, W.; Heinz, M.; Henry, T.W.; Hepplemann, S.; Hippolyte,B.; Hirsch, A.; Hjort, E.; Hoffman, A.M.; Hoffmann, G.W.; Horner, M.J.; Huang, H.Z.; Huang, S.L.; Hughes, E.W.; Humanic, T.J.; Igo, G.; Jacobs,P.; Jacobs, W.W.; Jakl, P.; Jia, F.; Jiang, H.; Jones, P.G.; Judd, E.G.; Kabana, S.; Kang, K.; Kapitan, J.; Kaplan, M.; Keane, D.; Kechechyan, A.; Khodyrev, V.Yu.; Kim, B.C.; Kiryluk, J.; Kisiel, A.; Kislov, E.M.; Klein,S.R.; Kocoloski, A.; Koetke, D.D.; et al.

    2006-07-11

    The STAR collaboration at RHIC reports measurements of theinclusive yield of non-photonic electrons, which arise dominantly fromsemi-leptonic decays of heavy flavor mesons, over a broad range oftransverse momenta (1.2Au, and AuAucollisions at sqrt sNN = 200 GeV. The non-photonic electron yieldexhibits unexpectedly large suppression in central AuAu collisions athigh pt, suggesting substantial heavy quark energy loss at RHIC. Thecentrality and \\pt dependences of the suppression provide constraints ontheoretical models of suppression.

  9. Transverse-momentum dependent modification of dynamic texture in central Au+Au collisions at sqrt(sNN) = 200 GeV

    SciTech Connect (OSTI)

    Adams, J.; Aggarwal, M.M.; Ahammed, Z.; Amonett, J.; Anderson, B.D.; Arkhipkin, D.; Averichev, G.S.; Badyal, S.K.; Bai, Y.; Balewski, J.; Barannikova, O.; Barnby, L.S.; Baudot, J.; Bekele, S.; Belaga, V.V.; Bellwied, R.; Berger, J.; Bezverkhny, B.I.; Bharadwaj, S.; Bhasin, A.; Bhati, A.K.; Bhatia, V.S.; Bichsel, H.; Billmeier, A.; Bland, L.C.; Blyth, C.O.; Bonner, B.E.; Botje, M.; Boucham, A.; Brandin, A.V.; Bravar, A.; Bystersky, M.; Cadman, R.V.; Cai, X.Z.; Caines, H.; Calderon de la Barca Sanchez, M.; Castillo, J.; Cebra, D.; Chajecki, Z.; Chaloupka, P.; Chattopadhyay, S.; Chen, H.F.; Chen, Y.; Cheng, J.; Cherney, M.; Chikanian, A.; Christie, W.; Coffin, J.P.; Cormier, T.M.; Cramer, J.G.; Crawford, H.J.; Das, D.; Das, S.; de Moura, M.M.; Derevschikov, A.A.; Didenko, L.; Dietel, T.; Dogra, S.M.; Dong, W.J.; Dong, X.; Draper, J.E.; Du, F.; Dubey, A.K.; Dunin, V.B.; Dunlop, J.C.; Dutta Mazumdar, M.R.; Eckardt, V.; Edwards, W.R.; Efimov, L.G.; Emelianov, V.; Engelage, J.; Eppley, G.; Erazmus, B.; Estienne, M.; Fachini, P.; Faivre, J.; Fatemi, R.; Fedorisin, J.; Filimonov, K.; Filip, P.; Finch, E.; Fine, V.; Fisyak, Y.; Fomenko, K.; Fu, J.; Gagliardi, C.A.; Gans, J.; Ganti, M.S.; Gaudichet, L.; Geurts, F.; Ghazikhanian, V.; Ghosh, P.; Gonzalez, J.E.; Grachov, O.; Grebenyuk, O.; Grosnick, D.; Guertin, S.M.; Guo, Y.; Gupta, A.; Gutierrez, T.D.; Hallman, T.J.; Hamed, A.; Hardtke, D.; Harris, J.W.; Heinz, M.; Henry, T.W.; Hepplemann, S.; Hippolyte, B.; Hirsch, A.; Hjort, E.; Hoffmann, G.W.; Huang, H.Z.; Huang, S.L.; Hughes, E.W.; Humanic, T.J.; Igo, G.; Ishihara, A.; Jacobs, P.; Jacobs, W.W.; Janik, M.; Jiang, H.; Jones, P.G.; Judd, E.G.; Kabana, S.; Kang, K.; Kaplan, M.; Keane, D.; Khodyrev, V.Yu.; Kiryluk, J.; Kisiel, A.; Kislov, E.M.; Klay, J.; Klein, S.R.; Klyachko, A.; Koetke, D.D.; Kollegger, T.; Kopytine, S.M.; Kotchenda, L.; Kramer, M.; Kravtsov, P.; Kravtsov, V.I.; Krueger, K.; Kuhn, C.; Kulikov, A.I.; Kumar, A.; Kutuev, R.Kh.; et al.

    2005-01-10

    Correlations in the hadron distributions produced in relativistic Au+Au collisions are studied in the discrete wavelet expansion method. The analysis is performed in the space of pseudorapidity (|{eta}| {le} 1) and azimuth (full 2{pi}) in bins of transverse momentum (p{sub t}) from 0.14 {le} p{sub t} {le} 2.1 GeV/c. In peripheral Au+Au collisions a correlation structure ascribed to minijet fragmentation is observed. It evolves with collision centrality and p{sub t} in a way not seen before which suggests strong dissipation of minijet fragmentation in the longitudinally-expanding medium.

  10. Spin noise spectroscopy of ZnO

    SciTech Connect (OSTI)

    Horn, H.; Berski, F.; Hbner, J.; Oestreich, M.; Balocchi, A.; Marie, X.; Mansur-Al-Suleiman, M.; Bakin, A.; Waag, A.

    2013-12-04

    We investigate the thermal equilibrium dynamics of electron spins bound to donors in nanoporous ZnO by optical spin noise spectroscopy. The spin noise spectra reveal two noise contributions: A weak spin noise signal from undisturbed localized donor electrons with a dephasing time of 24 ns due to hyperfine interaction and a strong spin noise signal with a spin dephasing time of 5 ns which we attribute to localized donor electrons which interact with lattice defects.

  11. Injection and acceleration of Au31+ in the BNL AGS.

    SciTech Connect (OSTI)

    Fischer,W.; Ahrens, L.; Brown, K.; Gardner, C.; Glenn, W.; Huang, H.; Mapes, M.; Smart, L.; Thieberger, P.; Tsoupas, N.; Zhang, S.Y.; Zeno, K.; Omet, C.; Spiller, P.

    2008-06-23

    Injection and acceleration of ions in a lower charge state reduces space charge effects, and, if further elcctron stripping is needed, may allow elimination of a stripping stage and the associated beam losses. The former is of interest to the accelerators in the GSI FAIR complex, the latter for BNL RHIC collider operation at energies lower than the current injection energy. Lower charge state ions, however, have a higher likelihood of electron stripping which can lead to dynamic pressures rises and subsequent beam losses. We report on experiments in the AGS where Au{sup 31+} ions were injected and accelerated instead of the normally used Au{sup 77+} ions. Beam intensities and the average pressure in the AGS ring are recorded, and compared with calculations for dynamic pressures and beam losses. The experimental results will be used to benchmark the StrahlSim dynamic vacuum code and will be incorporated in the GSI FAIR SIS100 design.

  12. Local spectroscopy of a kondo impurity: Co on Au(111)

    SciTech Connect (OSTI)

    Madhavan, V.; Chen, W.; Jamneala, T.; Crommie, M.F.; Wingreen, N.S.

    2001-07-15

    We present a detailed study of the local electronic properties of the Kondo system formed from cobalt adatoms deposited onto Au(111) at a temperature of 6.6 K. Cryogenic scanning-tunneling spectroscopy was used to observe impurity-induced resonances at the Fermi energy and at the Au(111) surface-state band edge. The line shape of the Fermi-energy resonance, identified as a Kondo resonance, is observed to vary with lateral position from the impurity center and with impurity binding position on the reconstructed Au(111) surface. Little vertical dependence is seen in the resonance line shape for positions above the center of the impurity. Interaction effects between Kondo impurities are observed to remain small as cobalt coverage is increased up to 1 ML on the gold surface. The Kondo resonance is shown theoretically to be a member of a general class of Fano resonances arising from the interaction of a discrete impurity state with a conduction-electron continuum. The asymmetric line shape of the resonance thus reflects quantum interference between the d orbital and continuum conduction electron channels, as well as their coupling to the STM tip.

  13. Stable highly conductive ZnO via reduction of Zn vacancies

    SciTech Connect (OSTI)

    Look, David C.; Droubay, Timothy C.; Chambers, Scott A.

    2012-09-04

    Growth of Ga-doped ZnO by pulsed laser deposition at 200 ?C in an ambient of Ar and H2 produces a resistivity ? of ~ 1.5 x 10-4 ?-cm, stable to 500 ?C. Annealing on Zn foil reduces ? to ~ 1.2 x 10-4 ?-cm, one of the lowest values ever reported. The key is reducing the Zn-vacancy acceptor concentration NA to 5 x 1019, only 3% of the Ga-donor concentration ND of 1.6 x 1021 cm-3, with ND and NA determined from a degenerate mobility theory. The plasmonic wavelength is 1060 nm, further bridging the gap between metals and semiconductors.

  14. Electronic Structure and Optical Properties of Cu2ZnGeSe4. First-Principles Calculations and Vacuum-Ultraviolet Spectroscopic Ellipsometric Studies

    SciTech Connect (OSTI)

    Choi, Sukgeun; Park, Ji-Sang; Donohue, Andrea; Christensen, Steven T.; To, Bobby; Beall, Carolyn; Wei, Su-Huai; Repins, Ingid L.

    2015-11-19

    Cu2ZnGeSe4 is of interest for the development of next-generation thin-film photovoltaic technologies. To understand its electronic structure and related fundamental optical properties, we perform first-principles calculations for three structural variations: kesterite, stannite, and primitive-mixed CuAu phases. The calculated data are compared with the room-temperature dielectric function?=?1+i?2 spectrum of polycrystalline Cu2ZnGeSe4 determined by vacuum-ultraviolet spectroscopic ellipsometry in the photon-energy range of 0.7 to 9.0 eV. Ellipsometric data are modeled with the sum of eight Tauc-Lorentz oscillators, and the best-fit model yields the band-gap and Tauc-gap energies of 1.25 and 1.19 eV, respectively. A comparison of overall peak shapes and relative intensities between experimental spectra and the calculated ? data for three structural variations suggests that the sample may not have a pure (ordered) kesterite phase. We found that the complex refractive index N=n+ik, normal-incidence reflectivity R, and absorption coefficients ? are calculated from the modeled ? spectrum, which are also compared with those of Cu2ZnSnSe4 . The spectral features for Cu2ZnGeSe4 appear to be weaker and broader than those for Cu2ZnSnSe4 , which is possibly due to more structural imperfections presented in Cu2ZnGeSe4 than Cu2ZnSnSe4 .

  15. Measurements of Transverse Energy Distributions in Au+Au Collisions at {radical}s{sub NN} = 200 GeV

    SciTech Connect (OSTI)

    Adams, J.; Aggarwal, M.M.; Ahammed, Z.; Amonett, J.; Anderson, B.D.; Arkhipkin, D.; Averichev, G.S.; Bai, Y.; Balewski, J.; Barannikova, O.; Barnby, L.S.; Baudot, J.; Bekele, S.; Belaga, V.V.; Bellwied, R.; Berger, J.; Bezverkhny, B.I.; Bharadwaj, S.; Bhatia, V.S.; Bichsel, H.; Billmeier, A.; Bland, L.C.; Blyth, C.O.; Bonner, B.E.; Boucham, A.; Botje, M.; Brandin, A.; Bravar, A.; Bystersky, M.; Cadman, R.V.; Cai, X.Z.; Caines, H.; Calderon de la Barca Sanchez, M.; Carroll, J.; Castillo, J.; Cebra, D.; Chajecki, Z.; Chaloupka, P.; Chattopdhyay, S.; Chen, H.F.; Chen, Y.; Cheng, J.; Cherney, M.; Chikanian, A.; Christie, W.; Coffin, J.P.; Cormier, T.M.; Cramer, J.G.; Crawford, H.J.; Das, D.; Das, S.; de Moura, M.M.; Derevschikov, A.A.; Didenko, L.; Dietel, T.; Dong, W.J.; Dong, X.; Draper, J.E.; Du, F.; Dubey, A.K.; Dunin, V.B.; Dunlop, J.C.; Dutta Mazumdar, M.R>; Eckardt, V.; Edwards, W.R.; Efimov, L.G.; Emelianov, V.; Engelage, J.; Eppley, G.; Erazmus, B.; Estienne, M.; Fachini, P.; Faivre, J.; Fatemi, R.; Filimonov, K.; Finch, E.; Fine, V.; Fisyak, Y.; Foley, K.J.; Fomenko, K.; Fu, J.; Gagliardi, C.A.; Gans, J.; Ganti, M.S.; Gaudichet, L.; Geurts, F.; Ghazikhanian, V.; Ghosh, P.; Gonzalez, J.E.; Grachov, O.; Grebenyuk, O.; Grosnick, D.; Guertin, S.M.; Guo, Y.; Gupta, A.; Gutierrez, T.D.; Hallman, T.J.; Hamed, A.; Hardtke, D.; Harris, J.W.; Heinz, M.; Henry, T.W.; Hepplemann, S.; Hippolyte, B.; Hirsch, A.; Hjort, E.; Hoffmann, G.W.; Huang, H.Z.; Huang, S.L.; Hughes, E.W.; Humanic, T.J.; Igo, G.; Ishihara, A.; Jacobs, P.; Jacobs, W.W.; Janik, M.; Jiang, H.; Jones, P.G.; Judd, E.G.; Kabana, S.; Kang, K.; Kaplan, M.; Keane, D.; Khodyrev, V.Yu.; Kiryluk, J.; Kisiel, A.; Kislov, E.M.; Klay, J.; Klein, S.R.; Klyachko, A.; Koetke, D.D.; Kollegger, T.; Kopytine, M.; Kotchenda, L.; Kramer, M.; Kravtsov, P.; Kravtsov, V.I.; Krueger, K.; Kuhn, C.; Kulikov, A.I.; Kumar, A.; Kunz, C.L.; Kutuev, R.Kh.; Kuznetsov, A.A.; Lamont, M.A.C.; et al.

    2004-07-02

    Transverse energy (E{sub T}) distributions have been measured for Au+Au collisions at {radical}s{sub NN} = 200 GeV by the STAR collaboration at RHIC. E{sub T} is constructed from its hadronic and electromagnetic components, which have been measured separately. E{sub T} production for the most central collisions is well described by several theoretical models whose common feature is large energy density achieved early in the fireball evolution. The magnitude and centrality dependence of E{sub T} per charged particle agrees well with measurements at lower collision energy, indicating that the growth in E{sub T} for larger collision energy results from the growth in particle production. The electromagnetic fraction of the total E{sub T} is consistent with a final state dominated by mesons and independent of centrality.

  16. Dielectron Azimuthal Anisotropy at mid-rapidity in Au+Au collisions at root s=200GeV

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Adamczyk, L.

    2014-12-11

    We report on the first measurement of the azimuthal anisotropy (v₂) of dielectrons (e⁺e⁻ pairs) at mid-rapidity from √(sNN)=200 GeV Au + Au collisions with the STAR detector at the Relativistic Heavy Ion Collider (RHIC), presented as a function of transverse momentum (pT) for different invariant-mass regions. In the mass region Mee<1.1 GeV/c² the dielectron v₂ measurements are found to be consistent with expectations from π⁰,η,ω, and Φ decay contributions. In the mass region 1.1ee<2.9GeV/c², the measured dielectron v₂ is consistent, within experimental uncertainties, with that from the cc¯ contributions.

  17. Dielectron Azimuthal Anisotropy at mid-rapidity in Au+Au collisions at root s=200GeV

    SciTech Connect (OSTI)

    Adamczyk, L.

    2014-12-11

    We report on the first measurement of the azimuthal anisotropy (v₂) of dielectrons (e⁺e⁻ pairs) at mid-rapidity from √(sNN)=200 GeV Au + Au collisions with the STAR detector at the Relativistic Heavy Ion Collider (RHIC), presented as a function of transverse momentum (pT) for different invariant-mass regions. In the mass region Mee<1.1 GeV/c² the dielectron v₂ measurements are found to be consistent with expectations from π⁰,η,ω, and Φ decay contributions. In the mass region 1.1ee<2.9GeV/c², the measured dielectron v₂ is consistent, within experimental uncertainties, with that from the cc¯ contributions.

  18. Dielectron Azimuthal Anisotropy at mid-rapidity in Au+Au collisions at root s=200GeV

    SciTech Connect (OSTI)

    Adamczyk, L.; STAR Collaboration

    2014-12-01

    We report on the first measurement of the azimuthal anisotropy (v?) of dielectrons (e?e? pairs) at mid-rapidity from ?(sNN)=200 GeV Au + Au collisions with the STAR detector at the Relativistic Heavy Ion Collider (RHIC), presented as a function of transverse momentum (pT) for different invariant-mass regions. In the mass region Mee<1.1 GeV/c the dielectron v? measurements are found to be consistent with expectations from ??,?,?, and ? decay contributions. In the mass region 1.1ee<2.9GeV/c, the measured dielectron v? is consistent, within experimental uncertainties, with that from the cc contributions.

  19. Optical probing of MgZnO/ZnO heterointerface confinement potential energy levels

    SciTech Connect (OSTI)

    Solovyev, V. V.; Van'kov, A. B.; Kukushkin, I. V.; Falson, J.; Kozuka, Y.; Zhang, D.; Smet, J. H.; Maryenko, D.; Tsukazaki, A.; Kawasaki, M.

    2015-02-23

    Low-temperature photoluminescence and reflectance measurements were employed to study the optical transitions present in two-dimensional electron systems confined at Mg{sub x}Zn{sub 1x}O/ZnO heterojunctions. Transitions involving A- and B-holes and electrons from the two lowest subbands formed within the confinement potential are detected. In the studied density range of 2.06.5??10{sup 11?}cm{sup ?2}, the inter-subband splitting is measured and the first excited electron subband is shown to be empty of electrons.

  20. Ag@Au concave cuboctahedra: A unique probe for monitoring Au-catalyzed reduction and oxidation reactions by surface-enhanced Raman spectroscopy

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Zhang, Jiawei; Winget, Sarah A.; Wu, Yiren; Su, Dong; Sun, Xiaojun; Xie, Zhao -Xiong; Qin, Dong

    2016-01-26

    In this paper, we report a facile synthesis of Ag@Au concave cuboctahedra by titrating aqueous HAuCl4 into a suspension of Ag cuboctahedra in the presence of ascorbic acid (AA), NaOH, and poly(vinylpyrrolidone) (PVP) at room temperature. Initially, the Au atoms derived from the reduction of Au3+ by AA are conformally deposited on the entire surface of a Ag cuboctahedron. Upon the formation of a complete Au shell, however, the subsequently formed Au atoms are preferentially deposited onto the Au{100} facets, resulting in the formation of a Ag@Au cuboctahedron with concave structures at the sites of {111} facets. The concave cuboctahedramore » embrace excellent SERS activity that is more than 70-fold stronger than that of the original Ag cuboctahedra at an excitation wavelength of 785 nm. The concave cuboctahedra also exhibit remarkable stability in the presence of an oxidant such as H2O2 because of the protection by a complete Au shell. These two unique attributes enable in-situ SERS monitoring of the reduction of 4-nitrothiophenol (4-NTP) to 4-aminothiophenol (4-ATP) by NaBH4 through a 4,4'-dimercaptoazobenzene (trans-DMAB) intermediate and the subsequent oxidation of 4-ATP back to trans-DMAB upon the introduction of H2O2.« less

  1. Optical Properties of ZnO-Alloyed Nanocrystalline Films

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Che, Hui; Huso, Jesse; Morrison, John L.; Thapa, Dinesh; Huso, Michelle; Yeh, Wei Jiang; Tarun, M. C.; McCluskey, M. D.; Bergman, Leah

    2012-01-01

    ZnO is emore » merging as one of the materials of choice for UV applications. It has a deep excitonic energy level and a direct bandgap of ~3.4 eV. Alloying ZnO with certain atomic constituents adds new optical and electronic functionalities to ZnO. This paper presents research on M g x Z n 1 − x O and Z n S 1 − x O x nanocrystalline flexible films, which enable tunable optical properties in the deep-UV and in the visible range. The ZnO and Mg 0 .3 Zn 0 .7 O films were found to have bandgaps at 3.35 and 4.02 eV, respectively. The photoluminescence of the Mg 0 .3 Zn 0 .7 O exhibited a bandedge emission at 3.95 eV, and at lower energy 3.38 eV due to the limited solubility inherent to these alloys. ZnS 0 .76 O 0 .24 and ZnS 0 .16 O 0 .84 were found to have bandgaps at 3.21 and 2.65 eV, respectively. The effect of nitrogen doping on ZnS 0 .16 O 0 .84 is discussed in terms of the highly lattice mismatched nature of these alloys and the resulting valence-band modification.« less

  2. Formation of Pd/Au Nanostructures from Pd Nanowires via Galvanic Replacement Reaction

    SciTech Connect (OSTI)

    Teng,X.; Wang, Q.; Liu, P.; Han, W.; Frenkel, A.; Wen, W.; Marinkovic, N.; Hanson, J.; Rodriguez, J.

    2008-01-01

    Bimetallic nanostructures with non-random metal atoms distribution are very important for various applications. To synthesize such structures via benign wet chemistry approach remains challenging. This paper reports a synthesis of a Au/Pd alloy nanostructure through the galvanic replacement reaction between Pd ultrathin nanowires (2.4 {+-} 0.2 nm in width, over 30 nm in length) and AuCl3 in toluene. Both morphological and structural changes were monitored during the reaction up to 10 h. Continuous changes of chemical composition and crystalline structure from Pd nanowires to Pd68Au32 and Pd45Au55 alloys, and to Au nanoparticles were observed. More interestingly, by using combined techniques such as high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), energy dispersive X-ray spectrometry (EDS), UV-vis absorption, and extended X-ray absorption fine structure (EXAFS) spectroscopy, we found the formation of Pd68Au32 non-random alloy with Au-rich core and Pd-rich shell, and random Pd45Au55 alloy with uniformly mixed Pd and Au atom inside the nanoparticles, respectively. Density functional theory (DFT) calculations indicated that alkylamine will strongly stabilize Pd to the surface, resulting in diffusion of Au atoms into the core region to form a non-random alloy. We believe such benign synthetic techniques can also enable the large scale preparation of various types of non-random alloys for several technically important catalysis applications.

  3. Structural and phonon transmission study of Ge-Au-Ge eutectically bonded interfaces

    SciTech Connect (OSTI)

    Knowlton, W.B. |

    1995-07-01

    This thesis presents a structural analysis and phonon transparency investigation of the Ge-Au-Ge eutectic bond interface. Interface development was intended to maximize the interfacial ballistic phonon transparency to enhance the detection of the dark matter candidate WIMPs. The process which was developed provides an interface which produces minimal stress, low amounts of impurities, and insures Ge lattice continuity through the interface. For initial Au thicknesses of greater than 1,000 {angstrom} Au per substrate side, eutectic epitaxial growth resulted in a Au dendritic structure with 95% cross sectional and 90% planar Au interfacial area coverages. In sections in which Ge bridged the interface, lattice continuity across the interface was apparent. Epitaxial solidification of the eutectic interface with initial Au thicknesses < 500 A per substrate side produced Au agglomerations thereby reducing the Au planar interfacial area coverage to as little as 30%. The mechanism for Au coalescence was attributed to lateral diffusion of Ge and Au in the liquid phase during solidification. Phonon transmission studies were performed on eutectic interfaces with initial Au thicknesses of 1,000 {angstrom}, 500 {angstrom}, and 300 {angstrom} per substrate side. Phonon imaging of eutectically bonded samples with initial Au thicknesses of 300 {angstrom}/side revealed reproducible interfacial percent phonon transmissions from 60% to 70%. Line scan phonon imaging verified the results. Phonon propagation TOF spectra distinctly showed the predominant phonon propagation mode was ballistic. This was substantiated by phonon focusing effects apparent in the phonon imaging data. The degree of interface transparency to phonons and resulting phonon propagation modes correlate with the structure of the interface following eutectic solidification. Structural studies of samples with initial Au thickness of 1,000 {angstrom}/side appear to correspond with the phonon transmission study.

  4. K(892)* resonance production in Au+Au and p+p collisions at {radical}s{sub NN} = 200 GeV at RHIC

    SciTech Connect (OSTI)

    Adams, J.; Aggarwal, M.M.; Ahammed, Z.; Amonett, J.; Anderson, B.D.; Arkhipkin, D.; Averichev, G.S.; Badyal, S.K.; Bai, Y.; Balewski, J.; Barannikova, O.; Barnby, L.S.; Baudot, J.; Bekele, S.; Belaga, V.V.; Bellwied, R.; Berger, J.; Bezverkhny, B.I.; Bharadwaj, S.; Bhasin, A.; Bhati, A.K.; Bhatia, V.S.; Bichsel, H.; Billmeier, A.; Bland, L.C.; Blyth, C.O.; Bonner, B.E.; Botje, M.; Boucham, A.; Brandin, A.V.; Bravar, A.; Bystersky, M.; Cadman, R.V.; Cai, X.Z.; Caines, H.; Calderon de la Barca Sanchez, M.; Castillo, J.; Cebra, D.; Chajecki, Z.; Chaloupka, P.; Chattopadhyay, S.; Chen, H.F.; Chen, Y.; Cheng, J.; Cherney, M.; Chikanian, A.; Christie, W.; Coffin, J.P.; Cormier, T.M.; Cramer, J.G.; Crawford, H.J.; Das, D.; Das, S.; de Moura, M.M.; Derevschikov, A.A.; Didenko, L.; Dietel, T.; Dogra, S.M.; Dong, W.J.; Dong, X.; Draper, J.E.; Du, F.; Dubey, A.K.; Dunin, V.B.; Dunlop, J.C.; Dutta Mazumdar, M.R.; Eckardt, V.; Edwards, W.R.; Efimov, L.G.; Emelianov, V.; Engelage, J.; Eppley, G.; Erazmus, B.; Estienne, M.; Fachini, P.; Faivre, J.; Fatemi, R.; Fedorisin, J.; Filimonov, K.; Filip, P.; Finch, E.; Fine, V.; Fisyak, Y.; Fomenko, K.; Fu, J.; Gagliardi, C.A.; Gaillard, L.; Gans, J.; Ganti, M.S.; Gaudichet, L.; Geurts, F.; Ghazikhanian, V.; Ghosh, P.; Gonzalez, J.E.; Grachov, O.; Grebenyuk, O.; Grosnick, D.; Guertin, S.M.; Guo, Y.; Gupta, A.; Gutierrez, T.D.; Hallman, T.J.; Hamed, A.; Hardtke, D.; Harris, J.W.; Heinz, M.; Henry, T.W.; Hepplemann, S.; Hippolyte, B.; Hirsch, A.; Hjort, E.; Hoffmann, G.W.; Huang, H.Z.; Huang, S.L.; Hughes, E.W.; Humanic, T.J.; Igo, G.; Ishihara, A.; Jacobs, P.; Jacobs, W.W.; Janik, M.; Jiang, H.; Jones, P.G.; Judd, E.G.; Kabana, S.; Kang, K.; Kaplan, M.; Keane, D.; Khodyrev, V.Yu.; Kiryluk, J.; Kisiel, A.; Kislov, E.M.; Klay, J.; Klein, S.R.; Koetke, D.D.; Kollegger, T.; Kopytine, M.; Kotchenda, L.; Kramer, M.; Kravtsov, P.; Kravtsov, V.I.; Krueger, K.; Kuhn, C.; Kulikov, A.I.; Kumar, A.; Kutuev, R.Kh.; et al.

    2004-12-09

    The short-lived K(892)* resonance provides an efficient tool to probe properties of the hot and dense medium produced in relativistic heavy-ion collisions. We report measurements of K* in {radical}s{sub NN} = 200 GeV Au+Au and p+p collisions reconstructed via its hadronic decay channels K(892)*{sup 0} {yields} K{pi} and K(892)*{sup +-} {yields} K{sub S}{sup 0}{pi}{sup +-} using the STAR detector at RHIC. The K*{sup 0} mass has been studied as function of p{sub T} in minimum bias p + p and central Au+Au collisions. The K* p{sub T} spectra for minimum bias p + p interactions and for Au+Au collisions in different centralities are presented. The K*/K ratios for all centralities in Au+Au collisions are found to be significantly lower than the ratio in minimum bias p + p collisions, indicating the importance of hadronic interactions between chemical and kinetic freeze-outs. The nuclear modification factor of K* at intermediate p{sub T} is similar to that of K{sub S}{sup 0}, but different from {Lambda}. This establishes a baryon-meson effect over a mass effect in the particle production at intermediate p{sub T} (2 < p{sub T} {le} 4 GeV/c). A significant non-zero K*{sup 0} elliptic flow (v{sub 2}) is observed in Au+Au collisions and compared to the K{sub S}{sup 0} and {Lambda} v{sub 2}.

  5. The ZnO p-n homojunctions modulated by ZnMgO barriers

    SciTech Connect (OSTI)

    Yang, Jing-Jing; Fang, Qing-Qing Wang, Dan-Dan; Du, Wen-Han

    2015-04-15

    In this paper, we fabricated the ultrathin ZnO p-n homojunctions, which modulated by ZnMgO asymmetrical double barriers (ADB). The ADB p-n homojunctions displays step-like curve in the absorption spectrums, this is the first time that quantum confinement effect has been observed in the absorption spectrums at room temperature (RT). The Hall-effect data confirm there is 2-dimensional electron gas in the interface of the ZnMgO ADB p-n junctions. The quantum confinement effect enhances the hall-mobility μ to 10{sup 3} cm{sup 2}V {sup −1}s{sup −1} based on the polarity of the films. There was no rectification property in the ZnO homojunctions with thickness of 250nm, however, when the ADB was added in the n-type layer of the homojunctions, it displays a typical Zener diode rectification property in the I-V curve.

  6. Hierarchical ZnO Structures Templated with Amino Acid Based Surfactant...

    Office of Scientific and Technical Information (OSTI)

    Hierarchical ZnO Structures Templated with Amino Acid Based Surfactants Citation Details In-Document Search Title: Hierarchical ZnO Structures Templated with Amino Acid Based ...

  7. Neutral nitrogen acceptors in ZnO: The {sup 67}Zn hyperfine interactions

    SciTech Connect (OSTI)

    Golden, E. M.; Giles, N. C.; Evans, S. M.; Halliburton, L. E.

    2014-03-14

    Electron paramagnetic resonance (EPR) is used to characterize the {sup 67}Zn hyperfine interactions associated with neutral nitrogen acceptors in zinc oxide. Data are obtained from an n-type bulk crystal grown by the seeded chemical vapor transport method. Singly ionized nitrogen acceptors (N{sup −}) initially present in the crystal are converted to their paramagnetic neutral charge state (N{sup 0}) during exposure at low temperature to 442 or 633 nm laser light. The EPR signals from these N{sup 0} acceptors are best observed near 5 K. Nitrogen substitutes for oxygen ions and has four nearest-neighbor cations. The zinc ion along the [0001] direction is referred to as an axial neighbor and the three equivalent zinc ions in the basal plane are referred to as nonaxial neighbors. For axial neighbors, the {sup 67}Zn hyperfine parameters are A{sub ‖} = 37.0 MHz and A{sub ⊥} = 8.4 MHz with the unique direction being [0001]. For nonaxial neighbors, the {sup 67}Zn parameters are A{sub 1} = 14.5 MHz, A{sub 2} = 18.3 MHz, and A{sub 3} = 20.5 MHz with A{sub 3} along a [101{sup ¯}0] direction (i.e., in the basal plane toward the nitrogen) and A{sub 2} along the [0001] direction. These {sup 67}Zn results and the related {sup 14}N hyperfine parameters provide information about the distribution of unpaired spin density at substitutional neutral nitrogen acceptors in ZnO.

  8. Identification of {gamma} rays from {sup 172}Au and {alpha} decays of {sup 172}Au, {sup 168}Ir, and {sup 164}Re

    SciTech Connect (OSTI)

    Hadinia, B.; Cederwall, B.; Andgren, K.; Baeck, T.; Johnson, A.; Khaplanov, A.; Wyss, R.; Page, R. D.; Grahn, T.; Paul, E. S.; Sandzelius, M.; Scholey, C.; Greenlees, P. T.; Jakobsson, U.; Jones, P. M.; Julin, R.; Juutinen, J.; Ketelhut, S.; Leino, M.; Nyman, M.

    2009-12-15

    The very neutron deficient odd-odd nucleus {sup 172}Au was studied in reactions of 342 and 348 MeV {sup 78}Kr beams with an isotopically enriched {sup 96}Ru target. The {alpha} decays previously reported for {sup 172}Au were confirmed and the decay chain extended down to {sup 152}Tm through the discovery of a new {alpha}-decaying state in {sup 164}Re[E{sub {alpha}}=5623(10) keV; t{sub 1/2}=864{sub -110}{sup +150} ms; b{sub {alpha}}=3(1)%]. Fine structure in these {alpha} decays of {sup 172}Au and {sup 168}Ir were identified. A new {alpha}-decaying state was also observed and assigned as the ground state in {sup 172}Au[E{sub {alpha}}=6762(10) keV; t{sub 1/2}=22{sub -5}{sup +6} ms]. This decay chain was also correlated down to {sup 152}Tm through previously reported {alpha} decays. Prompt {gamma} rays from excited states in {sup 172}Au have been identified using the recoil-decay tagging technique. The partial level scheme constructed for {sup 172}Au indicates that it has an irregular structure. Possible configurations of the {alpha}-decaying states in {sup 172}Au are discussed in terms of the systematics of nuclei in this region and total Routhian surface calculations.

  9. Mobility of indium on the ZnO(0001) surface

    SciTech Connect (OSTI)

    Heinhold, R.; Reeves, R. J.; Allen, M. W.; Williams, G. T.; Evans, D. A.

    2015-02-02

    The mobility of indium on the Zn-polar (0001) surface of single crystal ZnO wafers was investigated using real-time x-ray photoelectron spectroscopy. A sudden transition in the wettability of the ZnO(0001) surface was observed at ∼520 °C, with indium migrating from the (0001{sup ¯}) underside of the wafer, around the non-polar (11{sup ¯}00) and (112{sup ¯}0) sidewalls, to form a uniform self-organized (∼20 Å) adlayer. The In adlayer was oxidized, in agreement with the first principles calculations of Northrup and Neugebauer that In{sub 2}O{sub 3} precipitation can only be avoided under a combination of In-rich and Zn-rich conditions. These findings suggest that unintentional In adlayers may form during the epitaxial growth of ZnO on indium-bonded substrates.

  10. Electrodeposition of Zn based nanostructure thin films for photovoltaic applications

    SciTech Connect (OSTI)

    Al-Bathi, S. A. M.

    2015-03-30

    We present here a systematic study on the synthesis thin films of various ZnO, CdO, Zn{sub x}Cd{sub 1-x} (O) and ZnTe nanostructures by electrodeposition technique with ZnCl{sub 2,} CdCl{sub 2} and ZnSO{sub 4} solution as starting reactant. Several reaction parameters were examined to develop an optimal procedure for controlling the size, shape, and surface morphology of the nanostructure. The results showed that the morphology of the products can be carefully controlled through adjusting the concentration of the electrolyte. The products present well shaped Nanorods arrays at specific concentration and temperature. UV-VIS spectroscopy and X-ray diffraction results show that the product presents good crystallinity. A possible formation process has been proposed.

  11. Examination of charge transfer in Au/YSZ for high-temperature optical gas sensing

    SciTech Connect (OSTI)

    Baltrus, John P.; Ohodnicki, Paul R.

    2014-01-01

    Au-nanoparticle incorporated oxide thin film materials demonstrate significant promise as functionalsensor materials for high temperature optical gas sensing in severe environments relevant for fossil andnuclear based power generation. The Au/yttria-stabilized zirconia (YSZ) system has been extensivelystudied in the literature and serves as a model system for fundamental investigations that seek to betterunderstand the mechanistic origin of the plasmonic gas sensing response. In this work, X-ray photoelec-tron spectroscopy techniques are applied to Au/YSZ films in an attempt to provide further experimentalevidence for a proposed sensing mechanism involving a change in free carrier density of Au nanoparticles due to charge transfer.

  12. Microwave Synthesis of Au?Rh Core?Shell Nanoparticles and Implications...

    Office of Scientific and Technical Information (OSTI)

    Microwave Synthesis of Au?Rh Core?Shell Nanoparticles and Implications of the Shell Thickness in Hydrogenation Catalysis Citation Details In-Document Search Title: Microwave ...

  13. Fabrication of two-dimensional Au at FePt core-shell nanoparticle...

    Office of Scientific and Technical Information (OSTI)

    In this report, we experimentally demonstrate that single platinum nanoparticles exhibit ... This finding is exploited for the parallel Au encapsulation of FePt nanoparticles arranged ...

  14. AuRu/AC as an effective catalyst for hydrogenation reactions

    SciTech Connect (OSTI)

    Villa, Alberto; Chan-Thaw, Carine E.; Campisi, Sebastiano; Bianchi, Claudia L.; Wang, Di; Kotula, Paul G.; Kübel, Christian; Prati, Laura

    2015-03-23

    AuRu bimetallic catalysts have been prepared by sequential deposition of Au on Ru or vice versa obtaining different nanostructures: when Ru has been deposited on Au, a Aucore–Rushell has been observed, whereas the deposition of Au on Ru leads to a bimetallic phase with Ru enrichment on the surface. In the latter case, the unexpected Ru enrichment could be attributed to the weak adhesion of Ru on the carbon support, thus allowing Ru particles to diffuse on Au particles. Both structures result very active in catalysing the liquid phase hydrogenolysis of glycerol and levulinic acid but the activity, the selectivity and the stability depend on the structure of the bimetallic nanoparticles. Ru@Au/AC core–shell structure mostly behaved as the monometallic Ru, whereas the presence of bimetallic AuRu phase in Au@Ru/AC provides a great beneficial effect on both activity and stability.

  15. Stimulated electroluminescence emission from n-ZnO/p-GaAs:Zn heterojunctions fabricated by electro-deposition

    SciTech Connect (OSTI)

    K, P.; Tekmen, S.; Baltakesmez, A.; Tzemen, S.; Meral, K.; Onganer, Y.

    2013-12-15

    In this study, n-ZnO thin films were electrochemically deposited on p-GaAs:Zn substrates. The XRD results of ZnO thin films deposited on p-GaAs:Zn substrates at potentials varied from ?0.9 V to ?1.2 V show a strong c-axis (002) orientation and homogeneity. The current-voltage characteristics exhibit rectification, proving a low turn-on voltage and an ideality factor of 4.71. The n-ZnO/p-GaAs heterostructures show blue-white electroluminescence (EL) emission, which is composed of broad emission bands. In addition to these broad peaks, stimulated emission also appear on the top of the spectra due to the multiple reflections from the mirror like surfaces of ZnO-ZnO and ZnO-GaAs interfaces. Besides, three broad photoluminescence (PL) emission peaks have also been observed peaking at respectively around 3.36 eV, 3.28 eV and 3.07 eV generally attributed to the near bandedge emission, the residual donor level and deep level emission due to the localized defects, respectively.

  16. ZnO/Cu(InGa)Se.sub.2 solar cells prepared by vapor phase Zn doping

    DOE Patents [OSTI]

    Ramanathan, Kannan; Hasoon, Falah S.; Asher, Sarah E.; Dolan, James; Keane, James C.

    2007-02-20

    A process for making a thin film ZnO/Cu(InGa)Se.sub.2 solar cell without depositing a buffer layer and by Zn doping from a vapor phase, comprising: depositing Cu(InGa)Se.sub.2 layer on a metal back contact deposited on a glass substrate; heating the Cu(InGa)Se.sub.2 layer on the metal back contact on the glass substrate to a temperature range between about 100.degree. C. to about 250.degree. C.; subjecting the heated layer of Cu(InGa)Se.sub.2 to an evaporant species from a Zn compound; and sputter depositing ZnO on the Zn compound evaporant species treated layer of Cu(InGa)Se.sub.2.

  17. Selective growth of catalyst-free ZnO nanowire arrays on Al:ZnO for device application

    SciTech Connect (OSTI)

    Chung, T. F.; Luo, L. B.; He, Z. B.; Leung, Y. H.; Shafiq, I.; Yao, Z. Q.; Lee, S. T.

    2007-12-03

    Vertically aligned ZnO nanowire (NW) arrays have been synthesized selectively on patterned aluminum-doped zinc oxide (AZO) layer deposited on silicon substrates without using any metal catalysts. The growth region was defined by conventional photolithography with an insulating template. Careful control of the types of template materials and growth conditions allows good alignment and growth selectivity for ZnO NW arrays. Sharp ultraviolet band-edge peak observed in the photoluminescence spectra of the patterned ZnO NW arrays reveals good optical qualities. The current-voltage characteristics of ZnO NWs/AZO/p-Si device suggest that patterned and aligned ZnO NW arrays on AZO may be used in optoelectronic devices.

  18. Gold in the layered structures of R3Au7Sn3: From relativity to versatility

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Provino, Alessia; Steinberg, Simon Alexander; Smetana, Volodymyr; Paramanik, Uday; Manfrinetti, Pietro; Dhar, Sudesh Kumar; Mudring, Anja -Verena

    2016-07-11

    A new isotypic series of ternary rare earth element-gold-tetrel intermetallic compounds has been synthesized and their structures and properties have been characterized. R3Au7Sn3 (R = Y, La-Nd, Sm, Gd-Tm, Lu) crystallize with the hexagonal Gd3Au7Sn3 prototype (Pearson symbol hP26; P63/m, a = 8.110-8.372 Å, c = 9.351-9.609 Å, Vcell = 532.7-583.3 Å3, Z = 2), an ordered variant of the Cu10Sn3-type. Their structure is built up by GdPt2Sn-type layers, which feature edge-sharing Sn@Au6 trigonal antiprisms connected by trigonal R3 groups. Additional insertion of gold atoms leads to the formation of new homoatomic Au clusters, Au@Au6; alternatively, the structure can bemore » considered as a superstructural polyhedral packing of the ZrBeSi-type. The magnetization, heat ca-pacity and electrical resistivity have been measured for R3Au7Sn3 (R = Ce, Pr, Nd and Tb). All four compounds order antiferromagnetically with the highest TN of 13 K for Tb3Au7Sn3. In Ce3Au7Sn3, which has a TN of 2.9 K, the heat capacity and electrical resistivity data in zero and applied fields indicate the presence of Kondo interactions. The coefficient of the linear term in the electronic heat capacity, γ, derived from the heat capacity data below 0.5 K is 211 mJ/Ce mol K2 suggesting strong electronic correlations due to the Kondo interaction. The electronic structure calculations based on the projector augmented wave method for particular representatives of the series suggest different tendencies of the localized R-4f AOs to hybridize with the valence states. LMTO-based bonding analysis on the non-magnetic La3Au7Sn3 indicates that the integrated crystal orbital Hamilton popu-lations (COHPs) are dominated by the heteroatomic Au–Sn contacts; however, contributions from La–Au and La–Sn separations are significant, both together exceeding 40 % in the overall bonding. Furthermore, homoatomic Au–Au interactions are evident for the Au@Au6 units but, despite of the high atomic concentration of

  19. Air-gap gating of MgZnO/ZnO heterostructures

    SciTech Connect (OSTI)

    Tambo, T.; Falson, J. Kozuka, Y.; Maryenko, D.; Tsukazaki, A.; Kawasaki, M.

    2014-08-28

    The adaptation of air-gap dielectric based field-effect transistor technology to controlling the MgZnO/ZnO heterointerface confined two-dimensional electron system (2DES) is reported. We find it possible to tune the charge density of the 2DES via a gate electrode spatially separated from the heterostructure surface by a distance of 5??m. Under static gating, the observation of the quantum Hall effect suggests that the charge carrier density remains homogeneous, with the 2DES in the 3?mm square sample the sole conductor. The availability of this technology enables the exploration of the charge carrier density degree of freedom in the pristine sample limit.

  20. Mechanism of ternary breakup in the reaction {sup 197}Au+{sup 197}Au at 15A MeV

    SciTech Connect (OSTI)

    Tian Junlong; Wu Xizhen; Li Zhuxia; Zhao Kai; Zhang Yingxun; Li Xian; Yan Shiwei

    2010-11-15

    The mechanism of the ternary breakup of the very heavy system {sup 197}Au+{sup 197}Au at an energy of 15A MeV has been studied by using the improved quantum molecular dynamics model. The calculation results reproduce the characteristic features in ternary breakup events explored in a series of experiments; i.e., the masses of three fragments are comparable in size and the very fast, nearly collinear breakup of the colliding system is dominant in the ternary breakup events. Further, the evolution of the time scales of different ternary reaction modes and the behavior of mass distributions of three fragments with impact parameters are studied. The time evolution of the configurations of the composite reaction systems is also studied. We find that for most of the ternary breakup events with the features found in the experiments, the configuration of the composite system has two-preformed-neck shape. The study shows that those ternary breakup events having the characteristic features found in the experiments happen at relatively small impact parameter reactions, but not at peripheral reactions. The ternary breakup reaction at peripheral reactions belongs to binary breakup with a neck emission.

  1. Photon and neutral pion production in Au+Au collisions at {radical}s{sub NN} = 130 GeV

    SciTech Connect (OSTI)

    Adams, J.; Adler, C.; Aggarwal, M.M.; Ahammed, Z.; Amonett, J.; Anderson, B.D.; Anderson, M.; Arkhipkin, D.; Averichev, G.S.; Badyal, S.K.; Balewski, J.; Barannikova, O.; Barnby, L.S.; Baudot, J.; Bekele, S.; Belaga, V.V.; Bellwied, R.; Berger, J.; Bezverkhny, B.I.; Bhardwaj, S.; Bhaskar, P.; Bhati, A.K.; Bichsel, H.; Billmeier, A.; Bland, L.C.; Blyth, C.O.; Bonner, B. E.; Botje, M.; Boucham, A.; Brandin, A.; Bravar, A.; Cadman, R.V.; Cai, X.Z.; Caines, H.; Calderon de la Barca Sanchez, M.; Carroll, J.; Castillo, J.; Castro, M.; Cebra, D.; Chaloupka, P.; Chattopadhyay, S.; Chen, H.F.; Chen, Y.; Chernenko, S.P.; Cherney, M.; Chikanian, A.; Choi, B.; Christie, W.; Coffin, J.P.; Cormier, T.M.; Cramer, J.G.; Crawford, H.J.; Das, D.; Das, S.; Derevschikov, A.A.; Didenko, L.; Dietel, T.; Dong, X.; Draper, J.E.; Du, F.; Dubey, A.K.; Dunin, V.B.; Dunlop, J.C.; Dutta Majumdar, M.R.; Eckardt, V.; Efimov, L.G.; Emelianov, V.; Engelage, J.; Eppley, G.; Erazmus, B.; Estienne, M.; Fachini, P.; Faine, V.; Faivre, J.; Fatemi, R.; Filimonov, K.; Filip, P.; Finch, E.; Fisyak, Y.; Flierl, D.; Foley, K.J.; Fu, J.; Gagliardi, C.A.; Ganti, M.S.; Gutierrez, T.D.; Gagunashvili, N.; Gans, J.; Gaudichet, L.; Germain, M.; Geurts, F.; Ghazikhanian, V.; Ghosh, P.; Gonzalez, J.E.; Grachov, O.; Grigoriev, V.; Gronstal, S.; Grosnick, D.; Guedon, M.; Guertin, S.M.; Gupta, A.; Gushin, E.; Hallman, T.J.; Hardtke, D.; Harris, J.W.; Heinz, M.; Henry, T.W.; Heppelmann, S.; Herston, T.; Hippolyte, B.; Hirsch, A.; Hjort, E.; Hoffmann, G.W.; Horsley, M.; Huang, H.Z.; Huang, S.L.; Humanic, T.J.; Igo, G.; Ishihara, A.; Jacobs, P.; Jacobs, W.W.; Janik, M.; Johnson, I.; Jones, P.G.; Judd, E.G.; Kabana, S.; Kaneta, M.; Kaplan, M.; Keane, D.; Kiryluk, J.; Kisiel, A.; Klay, J.; Klein, S.R.; Klyachko, A.; Koetke, D.D.; Kollegger, T.; Konstantinov, A.S.; Kopytine, M.; Kotchenda, L.; Kovalenko, A.D.; Kramer, M.; Kravtsov, P.; Krueger, K.; Kuhn, C.; Kulikov, A.I.; Kumar, A.; et al.

    2004-01-08

    We report the first inclusive photon measurements about mid-rapidity (|y| < 0.5) from {sup 197}Au + {sup 197}Au collisions at {radical}s{sub NN} = 130 GeV at RHIC. Photon pair conversions were reconstructed from electron and positron tracks measured with the Time Projection Chamber (TPC) of the STAR experiment. With this method, an energy resolution of {Delta}E/E {approx} 2% at 0.5 GeV has been achieved. Reconstructed photons have also been used to measure the transverse momentum (p{sub t}) spectra of {pi}{sup 0} mesons about mid-rapidity (|y| < 1) via the {pi}{sup 0} {yields} {gamma}{gamma} decay channel. The fractional contribution of the {pi}{sup 0} {yields} {gamma}{gamma} decay to the inclusive photon spectrum decreases by 20% {+-} 5% between p{sub t} = 1.65 GeV/c and p{sub t} = 2.4 GeV/c in the most central events, indicating that relative to {pi}{sup 0} {yields} {gamma}{gamma} decay the contribution of other photon sources is substantially increasing.

  2. Identified Hadron Compositions in p+p and Au+Au Collisions at High Transverse Momenta at ?(sNN)=200 GeV

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Agakishiev, G.; Aggarwal, M. M.; Ahammed, Z.; Alakhverdyants, A. V.; Alekseev, I.; Alford, J.; Anderson, B. D.; Anson, C. D.; Arkhipkin, D.; Averichev, G. S.; et al

    2012-02-14

    We report transverse momentum (pT?15 GeV/c) spectra of ?, K, p, p?, K0S, and ?? at midrapidity in p+p and Au+Au collisions at ?(sNN)=200 GeV. Perturbative QCD calculations are consistent with ? spectra in p+p collisions but do not reproduce K and p(p?) spectra. The observed decreasing antiparticle-to-particle ratios with increasing pT provide experimental evidence for varying quark and gluon jet contributions to high-pT hadron yields. The relative hadron abundances in Au+Au at pT ? 8 GeV/c are measured to be similar to the p+p results, despite the expected Casimir effect for parton energy loss.

  3. Identified Hadron Compositions in p+p and Au+Au Collisions at High Transverse Momenta at √(sNN)=200 GeV

    SciTech Connect (OSTI)

    Agakishiev, G.; Aggarwal, M. M.; Ahammed, Z.; Alakhverdyants, A. V.; Alekseev, I.; Alford, J.; Anderson, B. D.; Anson, C. D.; Arkhipkin, D.; Averichev, G. S.; Balewski, J.; Barnby, L. S.; Beavis, D. R.; Bellwied, R.; Betancourt, M. J.; Betts, R. R.; Bhasin, A.; Bhati, A. K.; Bichsel, H.; Bielcik, J.; Bielcikova, J.; Bland, L. C.; Bordyuzhin, I. G.; Borowski, W.; Bouchet, J.; Braidot, E.; Brandin, A. V.; Brovko, S. G.; Bruna, E.; Bueltmann, S.; Bunzarov, I.; Burton, T. P.; Cai, X. Z.; Caines, H.; Calderón de la Barca Sánchez, M.; Cebra, D.; Cendejas, R.; Cervantes, M. C.; Chaloupka, P.; Chattopadhyay, S.; Chen, H. F.; Chen, J. H.; Chen, J. Y.; Chen, L.; Cheng, J.; Cherney, M.; Chikanian, A.; Christie, W.; Chung, P.; Codrington, M. J. M.; Corliss, R.; Cramer, J. G.; Crawford, H. J.; Cui, X.; Davila Leyva, A.; De Silva, L. C.; Debbe, R. R.; Dedovich, T. G.; Deng, J.; Derevschikov, A. A.; Derradi de Souza, R.; Didenko, L.; Djawotho, P.; Dong, X.; Drachenberg, J. L.; Draper, J. E.; Du, C. M.; Dunlop, J. C.; Efimov, L. G.; Elnimr, M.; Engelage, J.; Eppley, G.; Estienne, M.; Eun, L.; Evdokimov, O.; Fachini, P.; Fatemi, R.; Fedorisin, J.; Fersch, R. G.; Filip, P.; Finch, E.; Fine, V.; Fisyak, Y.; Gagliardi, C. A.; Gangadharan, D. R.; Geurts, F.; Ghosh, P.; Gorbunov, Y. N.; Gordon, A.; Grebenyuk, O. G.; Grosnick, D.; Gupta, A.; Gupta, S.; Guryn, W.; Haag, B.; Hajkova, O.; Hamed, A.; Han, L-X.; Harris, J. W.; Hays-Wehle, J. P.; Heppelmann, S.; Hirsch, A.; Hoffmann, G. W.; Hofman, D. J.; Huang, B.; Huang, H. Z.; Humanic, T. J.; Huo, L.; Igo, G.; Jacobs, W. W.; Jena, C.; Joseph, J.; Judd, E. G.; Kabana, S.; Kang, K.; Kapitan, J.; Kauder, K.; Ke, H. W.; Keane, D.; Kechechyan, A.; Kettler, D.; Kikola, D. P.; Kiryluk, J.; Kisiel, A.; Kizka, V.; Klein, S. R.; Koetke, D. D.; Kollegger, T.; Konzer, J.; Koralt, I.; Koroleva, L.; Korsch, W.; Kotchenda, L.; Kravtsov, P.; Krueger, K.; Kumar, L.; Lamont, M. A. C.; Landgraf, J. M.; LaPointe, S.; Lauret, J.; Lebedev, A.; Lednicky, R.; Lee, J. H.; Leight, W.; LeVine, M. J.; Li, C.; Li, L.; Li, W.; Li, X.; Li, X.; Li, Y.; Li, Z. M.; Lima, L. M.; Lisa, M. A.; Liu, F.; Ljubicic, T.; Llope, W. J.; Longacre, R. S.; Lu, Y.; Lukashov, E. V.; Luo, X.; Ma, G. L.; Ma, Y. G.; Mahapatra, D. P.; Majka, R.; Mall, O. I.; Margetis, S.; Markert, C.; Masui, H.; Matis, H. S.; McDonald, D.; McShane, T. S.; Meschanin, A.; Milner, R.; Minaev, N. G.; Mioduszewski, S.; Mitrovski, M. K.; Mohammed, Y.; Mohanty, B.; Mondal, M. M.; Morozov, B.; Morozov, D. A.; Munhoz, M. G.; Mustafa, M. K.; Naglis, M.; Nandi, B. K.; Nasim, Md.; Nayak, T. K.; Nogach, L. V.; Nurushev, S. B.; Odyniec, G.; Ogawa, A.; Oh, K.; Ohlson, A.; Okorokov, V.; Oldag, E. W.; Oliveira, R. A. N.; Olson, D.; Pachr, M.; Page, B. S.; Pal, S. K.; Pandit, Y.; Panebratsev, Y.; Pawlak, T.; Pei, H.; Peitzmann, T.; Perkins, C.; Peryt, W.; Pile, P.; Planinic, M.; Pluta, J.; Plyku, D.; Poljak, N.; Porter, J.; Poskanzer, A. M.; Powell, C. B.; Prindle, D.; Pruneau, C.; Pruthi, N. K.; Pujahari, P. R.; Putschke, J.; Qiu, H.; Raniwala, R.; Raniwala, S.; Ray, R. L.; Redwine, R.; Reed, R.; Ritter, H. G.; Roberts, J. B.; Rogachevskiy, O. V.; Romero, J. L.; Ruan, L.; Rusnak, J.; Sahoo, N. R.; Sakrejda, I.; Salur, S.; Sandweiss, J.; Sangaline, E.; Sarkar, A.; Schambach, J.; Scharenberg, R. P.; Schmah, A. M.; Schmitz, N.; Schuster, T. R.; Seele, J.; Seger, J.; Selyuzhenkov, I.; Seyboth, P.; Shah, N.; Shahaliev, E.; Shao, M.; Sharma, M.; Shi, S. S.; Shou, Q. Y.; Sichtermann, E. P.; Simon, F.; Singaraju, R. N.; Skoby, M. J.; Smirnov, N.; Solanki, D.; Sorensen, P.; deSouza, U. G.; Spinka, H. M.; Srivastava, B.; Stanislaus, T. D. S.; Steadman, S. G.; Stevens, J. R.; Stock, R.; Strikhanov, M.; Stringfellow, B.; Suaide, A. A. P.; Suarez, M. C.; Sumbera, M.; Sun, X. M.; Sun, Y.; Sun, Z.; Surrow, B.; Svirida, D. N.; Symons, T. J. M.; Szanto de Toledo, A.; Takahashi, J.; Tang, A. H.; Tang, Z.; Tarini, L. H.; Tarnowsky, T.; Thein, D.; Thomas, J. H.; Tian, J.; Timmins, A. R.; Tlusty, D.; Tokarev, M.; Trainor, T. A.; Trentalange, S.; Tribble, R. E.; Tribedy, P.; Trzeciak, B. A.; Tsai, O. D.; Ullrich, T.; Underwood, D. G.; Van Buren, G.; van Nieuwenhuizen, G.; Vanfossen, J. A.; Varma, R.; Vasconcelos, G. M. S.; Vasiliev, A. N.; Videbæk, F.; Viyogi, Y. P.; Vokal, S.; Voloshin, S. A.; Wada, M.; Walker, M.; Wang, F.; Wang, G.; Wang, H.; Wang, J. S.; Wang, Q.; Wang, X. L.; Wang, Y.; Webb, G.; Webb, J. C.; Westfall, G. D.; Whitten, C.; Wieman, H.; Wissink, S. W.; Witt, R.; Witzke, W.; Wu, Y. F.; Xiao, Z.; Xie, W.; Xu, H.; Xu, N.; Xu, Q. H.; Xu, W.; Xu, Y.; Xu, Z.; Xue, L.; Yang, Y.; Yang, Y.; Yepes, P.; Yip, K.; Yoo, I-K.; Zawisza, M.; Zbroszczyk, H.; Zhan, W.; Zhang, J. B.; Zhang, S.; Zhang, W. M.; Zhang, X. P.; Zhang, Y.; Zhang, Z. P.; Zhao, F.; Zhao, J.; Zhong, C.; Zhu, X.; Zhu, Y. H.; Zoulkarneeva, Y.

    2012-02-14

    We report transverse momentum (pT≤15 GeV/c) spectra of π±, K±, p, p̄, K0S, and ρ⁰ at midrapidity in p+p and Au+Au collisions at √(sNN)=200 GeV. Perturbative QCD calculations are consistent with π± spectra in p+p collisions but do not reproduce K and p(p̄) spectra. The observed decreasing antiparticle-to-particle ratios with increasing pT provide experimental evidence for varying quark and gluon jet contributions to high-pT hadron yields. The relative hadron abundances in Au+Au at pT ≳ 8 GeV/c are measured to be similar to the p+p results, despite the expected Casimir effect for parton energy loss.

  4. Identified Hadron Compositions in p+p and Au+Au Collisions at High Transverse Momenta at √(sNN)=200 GeV

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Agakishiev, G.; Aggarwal, M. M.; Ahammed, Z.; Alakhverdyants, A. V.; Alekseev, I.; Alford, J.; Anderson, B. D.; Anson, C. D.; Arkhipkin, D.; Averichev, G. S.; et al

    2012-02-14

    We report transverse momentum (pT≤15 GeV/c) spectra of π±, K±, p, p̄, K0S, and ρ⁰ at midrapidity in p+p and Au+Au collisions at √(sNN)=200 GeV. Perturbative QCD calculations are consistent with π± spectra in p+p collisions but do not reproduce K and p(p̄) spectra. The observed decreasing antiparticle-to-particle ratios with increasing pT provide experimental evidence for varying quark and gluon jet contributions to high-pT hadron yields. The relative hadron abundances in Au+Au at pT ≳ 8 GeV/c are measured to be similar to the p+p results, despite the expected Casimir effect for parton energy loss.

  5. Polarized Raman scattering of single ZnO nanorod

    SciTech Connect (OSTI)

    Yu, J. L. Lai, Y. F. Wang, Y. Z.; Cheng, S. Y.

    2014-01-21

    Polarized Raman scattering measurement on single wurtzite c-plane (001) ZnO nanorod grown by hydrothermal method has been performed at room temperature. The polarization dependence of the intensity of the Raman scattering for the phonon modes A{sub 1}(TO), E{sub 1}(TO), and E{sub 2}{sup high} in the ZnO nanorod are obtained. The deviations of polarization-dependent Raman spectroscopy from the prediction of Raman selection rules are observed, which can be attributed to the structure defects in the ZnO nanorod as confirmed by the comparison of the transmission electron microscopy, photoluminescence spectra as well as the polarization dependent Raman signal of the annealed and unannealed ZnO nanorod. The Raman tensor elements of A{sub 1}(TO) and E{sub 1}(TO) phonon modes normalized to that of the E{sub 2}{sup high} phonon mode are |a/d|=0.32±0.01, |b/d|=0.49±0.02, and |c/d|=0.23±0.01 for the unannealed ZnO nanorod, and |a/d|=0.33±0.01, |b/d|=0.45±0.01, and |c/d|=0.20±0.01 for the annealed ZnO nanorod, which shows strong anisotropy compared to that of bulk ZnO epilayer.

  6. Thermal nature of charmonium transverse momentum spectra from Au-Au collisions at the highest energies available at the BNL Relativistic Heavy Ion Collider (RHIC)

    SciTech Connect (OSTI)

    Akkelin, S. V.; Sinyukov, Yu. M.; Braun-Munzinger, P.

    2010-03-15

    We analyze the transverse momentum distribution of J/psi mesons produced in Au+Au collisions at the top RHIC energy within a blast-wave model that accounts for a possible inhomogeneity of the charmonium distribution and/or flow fluctuations. The results imply that the transverse momentum spectra of J/psi, phi, and OMEGA hadrons measured at the RHIC can be described well if kinetic freeze-out takes place just after chemical freeze-out for these particles.

  7. Multifunctional hybrid Fe2O3-Au nanoparticles for efficient plasmonic heating

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Murph, Simona E. Hunyadi; Larsen, George K.; Lascola, Robert J.

    2016-02-20

    We describe the synthesis and properties of multifunctional Fe2O3-Au nanoparticles produced by a wet chemical approach and investigate their photothermal properties using laser irradiation. Here, the composite Fe2O3-Au nanoparticles retain the properties of both materials, creating a multifunctional structure with excellent magnetic and plasmonic properties.

  8. Interface Reactions and Electrical Characteristics of Au/GaSb Contacts

    SciTech Connect (OSTI)

    H. Ehsani; R.J. Gutmann; G.W. Charache

    2000-07-07

    The reaction of Au with GaSb occurs at a relatively low temperature (100 C). Upon annealing, a AuSb{sub 2} compound and several Au-Ga phases are produced. Phase transitions occur toward higher Ga concentration with increasing annealing temperatures. Furthermore, the depth of the contact also increases with increased annealing temperature. They found that the AuSb{sub 2} compound forms on the GaSb surface, with the compound crystal partially ordered with respect to the substrate. The transition of Schottky- to ohmic-contact behavior in Au/n-type GaSb occurs simultaneously with the formation of the AuGa compound at about a 250 C annealing temperature. This ohmic contact forms without the segregation of dopants at the metallic compound/GaSb interface. Therefore it is postulated that transition from Schottky- to ohmic-contact behavior is obtained through a series of tunneling transitions of electrons through defects in the depletion region in the Au/n-type GaSb contacts. Contact resistivities of 6-7 x 10{sup -6} {Omega}-cm{sup 2} were obtained with the annealing temperature between 300 and 350 C for 30 seconds. In Au/p-type GaSb contacts, the resistivity was independent of the annealing temperature. This suggested that the carrier transport in p-type contact dominated by thermionic emission.

  9. Electrodeposition of zinc on glassy carbon from ZnCl/sub 2/ and ZnBr/sub 2/ electrolytes

    SciTech Connect (OSTI)

    McBreen, J.; Gannon, E.

    1983-08-01

    The initial stages of the electrocrystallization of zinc from 3M ZnCl/sub 2/ and 3M ZnBr/sub 2/ on glassy carbon has been investigated using cyclic voltametry, the potential step method, and scanning electron microscopy. Particular care was taken to ensure electrolyte purity and to eliminate resistance effects in the measurements. The nucleation overvoltage in 3M ZnCl/sub 2/ was about 17 and about 12 mV in 3M ZnBr/sub 2/. In 3M ZnCl/sub 2/, the current transients from the potential step measurements could be fitted to a simple model that assumes instantaneous nucleation followed by growth of three dimensional centers under kinetic control. A similar mechanism is operative for 3M ZnBr/sub 2/ at low overvoltages. At higher overvoltages, the current transient is governed by mixed kinetic and diffusion control and cannot be fitted to a simple model. The lower nucleation overvoltage and the faster kinetics in 3M ZnBr/sub 2/ is correlated with the lower stability constants for the zinc bromide complexes. Erroneous results are obtained when resistance effects are not accounted for.

  10. The low-temperature form of calcium gold stannide, CaAuSn

    SciTech Connect (OSTI)

    Lin, Qisheng; Corbett, John D.

    2014-07-19

    The EuAuGe-type CaAuSn phase has been synthesized and single-crystal X-ray diffraction analysis reveals that it has an ortho­rhom­bic symmetry (space group Imm2), with a = 4.5261 (7) Å, b = 7.1356 (11) Å and c = 7.8147 (11) Å. The structure features puckered layers that are connected by homoatomic Au-Au and Sn-Sn inter­layer bonds. This structure is one of the two parent structures of its high-temperature polymorph (ca 873 K), which is an inter­growth structure of the EuAuGe- and SrMgSi-type structures in a 2:3 ratio.

  11. Nuclear matter effects on J/? production in asymmetric Cu+Au collisions at ?SNN=200 GeV

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Adare, A.

    2014-12-18

    We report on J/? production from asymmetric Cu+Au heavy-ion collisions at ?sNN =200 GeV at the Relativistic Heavy Ion Collider at both forward (Cu-going direction) and backward (Au-going direction) rapidities. The nuclear modification of J/? yields in Cu+Au collisions in the Au-going direction is found to be comparable to that in Au+Au collisions when plotted as a function of the number of participating nucleons. In the Cu-going direction, J/? production shows a stronger suppression. This difference is comparable in magnitude and has the same sign as the difference expected from shadowing effects due to stronger low-x gluon suppression in themorelarger Au nucleus. The relative suppression is opposite to that expected from hot nuclear matter dissociation, since a higher energy density is expected in the Au-going direction.less

  12. Determination of the number density of excited and ground Zn atoms during rf magnetron sputtering of ZnO target

    SciTech Connect (OSTI)

    Maaloul, L.; Gangwar, R. K.; Stafford, L.

    2015-07-15

    A combination of optical absorption spectroscopy (OAS) and optical emission spectroscopy measurements was used to monitor the number density of Zn atoms in excited 4s4p ({sup 3}P{sub 2} and {sup 3}P{sub 0}) metastable states as well as in ground 4s{sup 2} ({sup 1}S{sub 0}) state in a 5 mTorr Ar radio-frequency (RF) magnetron sputtering plasma used for the deposition of ZnO-based thin films. OAS measurements revealed an increase by about one order of magnitude of Zn {sup 3}P{sub 2} and {sup 3}P{sub 0} metastable atoms by varying the self-bias voltage on the ZnO target from ?115 to ?300?V. Over the whole range of experimental conditions investigated, the triplet-to-singlet metastable density ratio was 5??1, which matches the statistical weight ratio of these states in Boltzmann equilibrium. Construction of a Boltzmann plot using all Zn I emission lines in the 200500?nm revealed a constant excitation temperature of 0.33??0.04?eV. In combination with measured populations of Zn {sup 3}P{sub 2} and {sup 3}P{sub 0} metastable atoms, this temperature was used to extrapolate the absolute number density of ground state Zn atoms. The results were found to be in excellent agreement with those obtained previously by actinometry on Zn atoms using Ar as the actinometer gas [L. Maaloul and L. Stafford, J. Vac. Sci. Technol., A 31, 061306 (2013)]. This set of data was then correlated to spectroscopic ellipsometry measurements of the deposition rate of Zn atoms on a Si substrate positioned at 12?cm away from the ZnO target. The deposition rate scaled linearly with the number density of Zn atoms. In sharp contrast with previous studies on RF magnetron sputtering of Cu targets, these findings indicate that metastable atoms play a negligible role on the plasma deposition dynamics of Zn-based coatings.

  13. Pressure-Induced Structural Transformations of ZnO Nanowires...

    Office of Scientific and Technical Information (OSTI)

    Journal Article: Pressure-Induced Structural Transformations of ZnO Nanowires Probed by X-ray Diffraction Citation Details In-Document Search Title: Pressure-Induced Structural ...

  14. Evolution of quasiparticle states with and without a Zn impurity...

    Office of Scientific and Technical Information (OSTI)

    Title: Evolution of quasiparticle states with and without a Zn impurity in doped 122 iron pnictides Authors: Pan, Lihua ; Li, Jian ; Tai, Yuan-Yen ; Graf, Matthias J. ; Zhu, ...

  15. Designing optical metamaterial with hyperbolic dispersion based on Al:ZnO/ZnO nano-layered structure using Atomic Layer Deposition technique

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Kelly, Priscilla; Liu, Mingzhao; Kuznetsova, Lyuba

    2016-04-07

    In this study, nano-layered Al:ZnO/ZnO hyperbolic dispersion metamaterial with a large number of layers was fabricated using the atomic layer deposition (ALD) technique. Experimental dielectric functions for Al:ZnO/ZnO structures are obtained by an ellipsometry technique in the visible and near-infrared spectral ranges. The theoretical modeling of the Al:ZnO/ZnO dielectric permittivity is done using effective medium approximation. A method for analysis of spectroscopic ellipsometry data is demonstrated to extract the optical permittivity for this highly anisotropic nano-layered metamaterial. The results of the ellipsometry analysis show that Al:ZnO/ZnO structures with a 1:9 ALD cycle ratio exhibit hyperbolic dispersion transition change near 1.8more » μm wavelength.« less

  16. Selective Zn2+ sensing using a modified bipyridine complex

    SciTech Connect (OSTI)

    Akula, Mahesh; El-Khoury, Patrick Z.; Nag, Amit; Bhattacharya, Anupam

    2014-06-01

    A novel fluorescent Zn2+ sensor, 4-(pyridin-2-yl)-3H-pyrrolo[2, 3-c]quinoline (PPQ), has been designed, synthesized and characterized by various spectroscopic and analytical techniques. PPQ exhibits superior detection of Zn2+ in the presence of various cations tested, including Cd2+ and Hg2+, via wavelength shifted fluorescence intensity enhancement. The emission wavelength at 500 nm, ensures probable noninterference from cellular components while performing biological applications.

  17. Measurements of dielectron production in Au + Au collisions at sNN=200 GeV from the STAR experiment

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Adamczyk, L.; Adkins, J. K.; Agakishiev, G.; Aggarwal, M. M.; Ahammed, Z.; Alekseev, I.; Alford, J.; Aparin, A.; Arkhipkin, D.; Aschenauer, E. C.; et al

    2015-08-24

    We report on measurements of dielectron (e⁺e⁻) production in Au+Au collisions at a center-of-mass energy of 200 GeV per nucleon-nucleon pair using the STAR detector at RHIC. Systematic measurements of the dielectron yield as a function of transverse momentum (pT) and collision centrality show an enhancement compared to a cocktail simulation of hadronic sources in the low invariant-mass region (Mee < 1GeV/c2). This enhancement cannot be reproduced by the ρ-meson vacuum spectral function. In minimum-bias collisions, in the invariant-mass range of 0.30 – 0.76GeV/c², integrated over the full pT acceptance, the enhancement factor is 1.76±0.06(stat.)±0.26(sys.)±0.29(cocktail). The enhancement factor exhibits weakmore » centrality and pT dependence in STAR's accessible kinematic regions, while the excess yield in this invariant-mass region as a function of the number of participating nucleons follows a power-law shape with a power of 1.44±0.10. Models that assume an in-medium broadening of the ρ-meson spectral function consistently describe the observed excess in these measurements. In addition, we report on measurements of ω- and Φ-meson production through their e⁺e⁻ decay channel. These measurements show good agreement with Tsallis blast-wave model predictions, as well as, in the case of the Φ meson, results through its K⁺K⁻ decay channel. In the intermediate invariant-mass region (1.1 < Mee < 3GeV/c²), we investigate the spectral shapes from different collision centralities. Physics implications for possible in-medium modification of charmed hadron production and other physics sources are discussed.« less

  18. High efficient ZnO nanowalnuts photocatalyst: A case study

    SciTech Connect (OSTI)

    Yan, Feng; Zhang, Siwen; Liu, Yang; Liu, Hongfeng; Qu, Fengyu; Cai, Xue; Wu, Xiang

    2014-11-15

    Highlights: • Walnut-like ZnO nanostructures are synthesized through a facile hydrothermal method. • Morphologies and microstructures of the as-obtained ZnO products were investigated. • The photocatalytic results demonstrate that methyl orange (MO) aqueous solution can be degraded over 97% after 45 min under UV light irradiation. - Abstract: Walnut-like ZnO nanostructures are successfully synthesized through a facile hydrothermal method. The structure and morphology of the as-synthesized products were characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM). The photocatalytic properties of ZnO nanowalnuts are investigated by photodegradating several organic dyes, such as Congo red (CR), methyl orange (MO) and eosin red aqueous solutions under UV irradiation, respectively. The results demonstrate that methyl orange (MO) aqueous solution can be degraded over 97% after 45 min under UV light irradiation. In addition, eosin red and Congo red (CR) aqueous solution degradation experiments are also conducted in the same condition, respectively. It showed that ZnO nanowalnuts represent high photocatalytic activities with a degradation efficiency of 87% for CR with 115 min of irradiation and 97% for eosin red with 55 min of irradiation. The reported ZnO products may be promising candidates as the photocatalysts in waste water treatment.

  19. Synthesis, structural, optical and Raman studies of pure and lanthanum doped ZnSe nanoparticles

    SciTech Connect (OSTI)

    Kumar, Pushpendra; Singh, Jai; Pandey, Mukesh Kumar; Jeyanthi, C.E.; Siddheswaran, R.; Paulraj, M.; Hui, K.N.; Hui, K.S.

    2014-01-01

    Graphical abstract: - Highlights: • Template-free synthesis of ZnSe and ZnSe:La nanoparticles was developed at low temperature 100 °C. • Cubic ZnSe and ZnSe:La nanoparticles were obtained by chemical route. • As-synthesized ZnSe:La nanoparticles showed higher emission intensity than ZnSe nanoparticles. • Band gap (E{sub g}) of ZnSe nanoparticles was bigger than ZnSe nanoparticles due to nanosized effect. - Abstract: In this work, a simple, effective and reproducible chemical synthetic route for the production of high-quality, pure ZnSe nanoparticles (NPs), and lanthanum-doped ZnSe (ZnSe:La) NPs is presented. The wide bandgap, luminescent pure ZnSe and ZnSe:La NPs has been synthesized at a low temperature (100 °C) in a single template-free step. The size and optical bandgap of the NPs was analyzed from powder X-ray diffraction (XRD), UV–visible (UV–vis) spectroscopy, transmission electron microscopy (TEM), and high resolution transmission electron microscopy (HRTEM). A broad photoluminescence (PL) emission across the visible spectrum has been demonstrated by a systematic blue-shift in emission due to the formation of small nanoparticles. Here, contribution to emission intensity from surface states of NPs increases with La doping. TEM data revealed that the average size of ZnSe and ZnSe:La NPs is 14 and 8 nm, respectively. On the other hand, band gap energy E{sub g} of ZnSe and ZnSe:La NPs were found to be 3.59 eV and 3.65 eV, respectively. Results showed that hydrazine hydrate played multiple roles in the formation of ZnSe and ZnSe:La NPs. A possible reaction mechanism for the growth of NPs is also discussed.

  20. Spray pyrolysis deposition of Cu-ZnO and Zn-SnO{sub 2} solar cells

    SciTech Connect (OSTI)

    Khelfane, A.; Tarzalt, H.; Sebboua, B.; Zerrouki, H.; Kesri, N.

    2015-12-31

    Large-gap metal oxides, such as titanium, tin, and zinc oxides, have attracted great interest because of their remarkable potential in dye-sensitized solar cells (DSSC) and their low cost and simple preparation procedure. In this work, we investigated several Zn-SnO{sub 2} and Cu-ZnO thin films that were sprayed under different experimental conditions. We varied [Zn/[Sn] and [Cu/[Zn] ratios, calculated on atomic percent in the starting solution. We report some structural results of the films using X-ray diffraction. Optical reflection and transmission spectra investigated by an UV/VIS/NIR spectrophotometer permit the determination of optical constants. The direct band gap was deduced from the photon energy dependence of the absorption coefficient.

  1. Glycerol Hydrogenolysis on Carbon-Supported PtRu and AuRu Bimetallic Catalysts

    SciTech Connect (OSTI)

    Maris,E.; Ketchie, W.; Murayama, M.; Davis, R.

    2007-01-01

    Bimetallic PtRu and AuRu catalysts were prepared by a surface redox method in which Pt or Au was deposited onto the surface of carbon-supported Ru nanoparticles with an average diameter of 2-3 nm. Characterization by H2 chemisorption, analytical TEM, and X-ray absorption spectroscopy at the Ru K-edge, Pt LIII-edge, and Au LIII-edge confirmed that Pt and Au were successfully deposited onto Ru without disrupting the Ru particles. Depression of the ethane hydrogenolysis rate over Ru after addition of Au provided further evidence of successful deposition. The bimetallic particles were subsequently evaluated in the aqueous-phase hydrogenolysis of glycerol at 473 K and 40 bar H2 at neutral and elevated pH. Although monometallic Pt and Ru exhibited different activities and selectivities to products, the bimetallic PtRu catalyst functioned more like Ru. A similar result was obtained for the AuRu bimetallic catalyst. The PtRu catalyst appeared to be stable under the aqueous-phase reaction conditions, whereas the AuRu catalyst was altered by the harsh conditions. Gold appeared to migrate off the Ru and agglomerate on the carbon during the reaction in liquid water.

  2. Effects of the proximity of Au nanoparticles on magnetic and transport properties of LSMO ultrathin layers

    SciTech Connect (OSTI)

    Brivio, S.; Magen Dominguez, Cesar; Sidorenko, A; Petti, D.; Cantoni, M.; Finazzi, M; Ciccacci, F; Renzi, R; Varela del Arco, Maria; Picozzi, S.; Bertacco, R.

    2010-01-01

    The effect of the proximity of Au nanoparticles on the transport and magnetic properties of ultrathin La2/3Sr1/3MnO3 (LSMO) films has been investigated. We find a huge increase of the resistivity of the manganite (by four orders of magnitude for a Au nominal thickness of 2 nm), which is accompanied by a strong decrease of the Curie temperature. A combined scanning transmission electron microscopy and electron energy loss spectroscopy (STEM-EELS) analysis shows that interfaces are coherent and atomically sharp, and that the structural quality is very high. On the other end, a strong reduction of the Mn oxidation state is seen upon Au capping. NMR data show a strong attenuation of the double exchange signal upon formation of Au nanoparticles. Ab-initio calculations indicate a negligible influence of Au on LSMO at an ideal interface, with the LSMO surface magnetic and electronic properties essentially unchanged upon creation of the Au/LSMO interface. In view of these calculations, the experimental results cannot be explained in terms of purely electrostatic effects induced by the proximity of a noble metal. Here we propose that the main driving force underlying the observed change in physical properties is the high reactivity of Au nanoparticles which can locally pump oxygen from the manganite, thus favouring a phase separation ensuing from O inhomogeneity which deteriorates the transport and electrical properties.

  3. MeV Au Ion Irradiation in Silicon and Nanocrystalline Zirconia Film Deposited on Silicon Substrate

    SciTech Connect (OSTI)

    Chang, Yongqin; Zhang, Yanwen; Zhu, Zihua; Edmondson, Philip D.; Weber, William J.

    2012-09-01

    Nanocrystalline zirconia (ZrO2) film with thickness of 305 nm deposited on a silicon substrate was irradiated with 2 MeV Au ions to different fluences at different temperatures. The implanted ion profiles were measured by time-of-flight secondary ion mass spectrometry (ToF-SIMS) and simulated using the stopping and range of ions inmatter (SRIM) code, respectively. The experimental results show that a large fraction of the incident Au ions penetrates through the ZrO2 film and are deposited into the Si substrate. At the interface of ZrO2 and Si, a sudden decrease of Au concentration is observed due to the much larger scattering cross section of Au in ZrO2 than in Si. The depth profile of the Au ions is measured in both the ZrO2 films and the Si substrates, and the results show that the Au distribution profiles do not exhibit a dependence on irradiation temperature. The local Au concentration increases proportionally with the irradiation fluence, suggesting that no thermal or irradiation-induced redistribution of the implanted Au ions. However, the Au concentration in the ZrO2 films, as determined by SIMS, is considerably lower than that predicted by the SRIM results, and the penetration depth from the SIMS measurements is much deeper than that from the SRIM predictions. These observations can be explained by an overestimation of the electronic stopping power, used in the SRIM program, for heavy incident ions in light targets. Over-estimation of the heavy-ion electronic stopping power may lead to errors in local dose calculation and underestimation of the projected range of slow heavy ions in targets that contain light elements. A quick estimate based on a reduced target density may be used to compensate the overestimation of the electronic stopping power in the SRIM program to provide better ion profile prediction.

  4. MeV Au Ion Irradiation in Silicon and Nanocrystalline Zirconia Film Deposited on Silicon Substrate

    SciTech Connect (OSTI)

    Chang, Yongqin; Zhang, Yanwen; Zhu, Zihua; Edmondson, Dr. Philip; Weber, William J

    2012-01-01

    Nanocrystalline zirconia (ZrO2) film with thickness of 305 nm deposited on a silicon substrate was irradiated with 2 MeV Au ions to different fluences at different temperatures. The implanted ion profiles were measured by time-of-flight secondary ion mass spectrometry (ToF-SIMS) and simulated using the stopping and range of ions in matter (SRIM) code, respectively. The experimental results show that a large fraction of the incident Au ions penetrates through the ZrO2 film and are deposited into the Si substrate. At the interface of ZrO2 and Si, a sudden decrease of Au concentration is observed due to the much larger scattering cross section of Au in ZrO2 than in Si. The depth profile of the Au ions is measured in both the ZrO2 films and the Si substrates, and the results show that the Au distribution profiles do not exhibit a dependence on irradiation temperature. The local Au concentration increases proportionally with the irradiation fluence, suggesting that no thermal or irradiation-induced redistribution of the implanted Au ions. However, the Au concentration in the ZrO2 films, as determined by SIMS, is considerably lower than that predicted by the SRIM results, and the penetration depth from the SIMS measurements is much deeper than that from the SRIM predictions. These observations can be explained by an overestimation of the electronic stopping power, used in the SRIM program, for heavy incident ions in light targets. Overestimation of the heavy-ion electronic stopping power may lead to errors in local dose calculation and underestimation of the projected range of slow heavy ions in targets that contain light elements. A quick estimate based on a reduced target density may be used to compensate the overestimation of the electronic stopping power in the SRIM program to provide better ion profile prediction.

  5. Growth and characterization of AuN films through the pulsed arc technique

    SciTech Connect (OSTI)

    Devia, A. Castillo, H.A.; Benavides, V.J.; Arango, Y.C.; Quintero, J.H.

    2008-02-15

    AuN films were produced through the PAPVD (Plasma Assisted Physics Vapor Deposition) method, using the pulsed arc technique in a mono-vaporizer noncommercial system, which consists of a chamber with two faced electrodes, and a power controlled system. In order to obtain the films, an Au Target with 99% purity and stainless steel 304 were used as target and substrate respectively. Nitrogen was injected in gaseous phase at 2.3 mbar pressure, and a discharge of 160 V was performed, supplied by the power controlled source. Au4f and N1s narrow spectra were analyzed using XPS (X-ray Photoelectron Spectroscopy)

  6. Supported Au-CuO Catalysts for Low Temperature CO Oxidation | Department of

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Energy Supported Au-CuO Catalysts for Low Temperature CO Oxidation Supported Au-CuO Catalysts for Low Temperature CO Oxidation Catalytic properties of Au-CuOx/SiO2 are investigated in removing pollutants from simulated automotive exhaust to meet an increasing demand for high emissions control at low temperatures. p-02_bauer.pdf (718.31 KB) More Documents & Publications Low Temperature Emission Control Vehicle Technologies Office Merit Review 2014: Low Temperature Emission Control to

  7. Enhanced efficiency of graphene-silicon Schottky junction solar cells by doping with Au nanoparticles

    SciTech Connect (OSTI)

    Liu, X.; Zhang, X. W. Yin, Z. G.; Meng, J. H.; Gao, H. L.; Zhang, L. Q.; Zhao, Y. J.; Wang, H. L.

    2014-11-03

    We have reported a method to enhance the performance of graphene-Si (Gr/Si) Schottky junction solar cells by introducing Au nanoparticles (NPs) onto the monolayer graphene and few-layer graphene. The electron transfer between Au NPs and graphene leads to the increased work function and enhanced electrical conductivity of graphene, resulting in a remarkable improvement of device efficiency. By optimizing the initial thickness of Au layers, the power conversion efficiency of Gr/Si solar cells can be increased by more than three times, with a maximum value of 7.34%. These results show a route for fabricating efficient and stable Gr/Si solar cells.

  8. Synthesis of reduced graphene oxide/ZnO nanorods composites on graphene coated PET flexible substrates

    SciTech Connect (OSTI)

    Huang, Lei, E-mail: leihuang@shnu.edu.cn; Guo, Guilue; Liu, Yang; Chang, Quanhong; Shi, Wangzhou

    2013-10-15

    Graphical abstract: - Highlights: ZnO nanorods synthesized on CVD-graphene and rGO surfaces, respectively. ZnO/CVD-graphene and ZnO/rGO form a distinctive porous 3D structure. rGO/ZnO nanostructures possibility in energy storage devices. - Abstract: In this work, reduced graphene oxide (rGO)/ZnO nanorods composites were synthesized on graphene coated PET flexible substrates. Both chemical vapor deposition (CVD) graphene and reduced graphene oxide (rGO) films were prepared following by hydrothermal growth of vertical aligned ZnO nanorods. Reduced graphene sheets were then spun coated on the ZnO materials to form a three dimensional (3D) porous nanostructure. The morphologies of the ZnO/CVD graphene and ZnO/rGO were investigated by SEM, which shows that the ZnO nanorods grown on rGO are larger in diameters and have lower density compared with those grown on CVD graphene substrate. As a result of fact, the rough surface of nano-scale ZnO on rGO film allows rGO droplets to seep into the large voids of ZnO nanorods, then to form the rGO/ZnO hierarchical structure. By comparison of the different results, we conclude that rGO/ZnO 3D nanostructure is more desirable for the application of energy storage devices.

  9. Improve the open-circuit voltage of ZnO solar cells with inserting ZnS layers by two ways

    SciTech Connect (OSTI)

    Sun, Yunfei; Yang, Jinghai; Yang, Lili; Cao, Jian; Gao, Ming; Zhang, Zhiqiang; Wang, Zhe; Song, Hang

    2013-04-15

    ZnS NPs layers were deposited on ZnO NRs by two different ways. One is spin coating; the other is successive ionic layer adsorption and reaction (SILAR) method. The ZnO NRs/ZnS NPs composites were verified by X-ray diffraction, X-ray photoelectron spectroscopy, and UVvisible spectrophotometer; their morphologies and thicknesses were examined by scanning electron microscopic and transmission electron microscopic images. The CdS quantum dot sensitized solar cells (QDSSCs) were constructed using ZnO NRs/ZnS NPs composites as photoanode and their photovoltaic characteristic was studied by JV curves. The results indicated that the way of SILAR is more beneficial for retarding the back transfer of electrons to CdS and electrolyte than spin coating method. The open-circuit voltage increased to 0.59 V by introducing a ZnS layer through SILAR method. When ZnS NPs layer was deposited for 10 times on ZnO NRs, the conversion efficiency of QDSSC shows ?3.3 folds increments of as-synthesized ZnO solar cell. - Graphical abstract: When ZnO nanorods were deposited by ZnS for 10 times, the conversion efficiency of QDSSC shows ?3.3 folds increments of as-synthesized ZnO solar cell. Highlights: ? ZnS layers were deposited with two different ways. ? The way of SILAR is more beneficial for retarding the back transfer of electrons. ? The open-circuit voltage increased to 0.59 V by introducing a ZnS layer through SILAR method.

  10. Efficient electrocatalytic conversion of CO.sub.2 to CO using ligand-protected Au.sub.25 clusters

    DOE Patents [OSTI]

    Kauffman, Douglas; Matranga, Christopher; Qian, Huifeng; Jin, Rongchao; Alfonso, Dominic R.

    2015-09-22

    An apparatus and method for CO.sub.2 reduction using an Au.sub.25 electrode. The Au.sub.25 electrode is comprised of ligand-protected Au.sub.25 having a structure comprising an icosahedral core of 13 atoms surrounded by a shell of six semi-ring structures bonded to the core of 13 atoms, where each semi-ring structure is typically --SR--Au--SR--Au--SR or --SeR--Au--SeR--Au--SeR. The 12 semi-ring gold atoms within the six semi-ring structures are stellated on 12 of the 20 faces of the icosahedron of the Au.sub.13 core, and organic ligand --SR or --SeR groups are bonded to the Au.sub.13 core with sulfur or selenium atoms. The Au.sub.25 electrode and a counter-electrode are in contact with an electrolyte comprising CO.sub.2 and H+, and a potential of at least -0.1 volts is applied from the Au.sub.25 electrode to the counter-electrode.

  11. CO Oxidation at the Interface of Au Nanoclusters and the Stepped-CeO2(111) Surface

    SciTech Connect (OSTI)

    Kim H. Y.; Henkelman, G.

    2013-01-14

    To reveal the richer chemistry of CO oxidation by CeO2 supported Au Nanoclusters NCs)/Nanoparticles, we design a Au12 supported on a stepped-CeO2 model (Au/CeO2-step) and study various kinds of CO oxidation mechanisms at the interface of the Au/CeO2-step: oxygen spillover from the CeO2 to the Au NCs;2 CO oxidation by the O2 bound to the Au-Ce3+ interface;3 and CO oxidation by the Mars-van Krevelen (M-vK) mechanism.4 DFT+U calculations show that lattice oxygen at the CeO2 step edge oxidizes CO bound to Au NCs by the M-vK mechanism. CO2 desorption determines the rate of CO oxidation and the vacancy formation energy (Evac) is a reactivity descriptor for CO oxidation. The maximum Evac that insures spontaneous CO2 production is higher for the Au/CeO2-step than the Au/CeO2-surface suggesting that the CeO2-step is a better supporting material than the CeO2-surface for CO oxidation by the Au/CeO2. Our results also suggest that for CO oxidation by Au NCs supported on nano- or meso-structured CeO2, which is the case of industrial catalysts, the M-vK mechanism accounts for a large portion of the total activity.

  12. Systematic study of azimuthal anisotropy in Cu + Cu and Au + Au collisions at √sNN = 62.4 and 200 GeV

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Adare, A.

    2015-09-23

    We have studied the dependence of azimuthal anisotropy v2 for inclusive and identified charged hadrons in Au+Au and Cu+Cu collisions on collision energy, species, and centrality. The values of v2 as a function of transverse momentum pT and centrality in Au+Au collisions at √sNN=200 and 62.4 GeV are the same within uncertainties. However, in Cu+Cu collisions we observe a decrease in v2 values as the collision energy is reduced from 200 to 62.4 GeV. The decrease is larger in the more peripheral collisions. By examining both Au+Au and Cu+Cu collisions we find that v2 depends both on eccentricity and themore » number of participants, Npart. We observe that v2 divided by eccentricity (ε) monotonically increases with Npart and scales as N1/3part. Thus, the Cu+Cu data at 62.4 GeV falls below the other scaled v2 data. For identified hadrons, v2 divided by the number of constituent quarks nq is independent of hadron species as a function of transverse kinetic energy KET=mT–m between 0.1T/nq<1 GeV. Combining all of the above scaling and normalizations, we observe a near-universal scaling, with the exception of the Cu+Cu data at 62.4 GeV, of v2/(nq∙ε∙N1/3part) vs KET/nq for all measured particles.« less

  13. Systematic study of azimuthal anisotropy in Cu + Cu and Au + Au collisions at √sNN = 62.4 and 200 GeV

    SciTech Connect (OSTI)

    Adare, A.

    2015-09-23

    We have studied the dependence of azimuthal anisotropy v2 for inclusive and identified charged hadrons in Au+Au and Cu+Cu collisions on collision energy, species, and centrality. The values of v2 as a function of transverse momentum pT and centrality in Au+Au collisions at √sNN=200 and 62.4 GeV are the same within uncertainties. However, in Cu+Cu collisions we observe a decrease in v2 values as the collision energy is reduced from 200 to 62.4 GeV. The decrease is larger in the more peripheral collisions. By examining both Au+Au and Cu+Cu collisions we find that v2 depends both on eccentricity and the number of participants, Npart. We observe that v2 divided by eccentricity (ε) monotonically increases with Npart and scales as N1/3part. Thus, the Cu+Cu data at 62.4 GeV falls below the other scaled v2 data. For identified hadrons, v2 divided by the number of constituent quarks nq is independent of hadron species as a function of transverse kinetic energy KET=mT–m between 0.1T/nq<1 GeV. Combining all of the above scaling and normalizations, we observe a near-universal scaling, with the exception of the Cu+Cu data at 62.4 GeV, of v2/(nq∙ε∙N1/3part) vs KET/nq for all measured particles.

  14. Gold-rich R3Au7Sn3: Establishing the interdependence between electronic features and physical properties

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Provino, Alessia; Steinberg, Simon; Smetana, Volodymyr; Kulkarni, Ruta; Dhar, Sudesh K.; Manfrinetti, Pietro; Mudring, Anja -Verena

    2015-05-18

    Two new polar intermetallic compounds Y3Au7Sn3 (I) and Gd3Au7Sn3 (II) have been synthesized and their structures have been determined by single crystal X-ray diffraction (P63/m; Z = 2, a = 8.148(1)/8.185(3), and c = 9.394(2)/9.415(3) for I/II, respectively). They can formally be assigned to the Cu10Sn3 type and consist of parallel slabs of Sn centered, edge-sharing trigonal Au6 antiprisms connected through R3 (R = Y, Gd) triangles. Additional Au atoms reside in the centres of trigonal Au6 prisms forming Au@Au6 clusters with Au–Au distances of 2.906–2.960 Å, while the R–R contacts in the R3 groups are considerably larger than themore »sums of their metallic radii. These exclusive structural arrangements provide alluring systems to study the synergism between strongly correlated systems, particularly, those in the structure of (II), and extensive polar intermetallic contacts, which has been inspected by measurements of the magnetic properties, heat capacities and electrical conductivities of both compounds. Gd3Au7Sn3 shows an antiferromagnetic ordering at 13 K, while Y3Au7Sn3 is a Pauli paramagnet and a downward curvature in its electrical resistivity at about 1.9 K points to a superconducting transition. DFT-based band structure calculations on R3Au7Sn3 (R = Y, Gd) account for the results of the conductivity measurements and different spin ordering models of (II) provide conclusive hints about its magnetic structure. As a result, chemical bonding analyses of both compounds indicate that the vast majority of bonding originates from the heteroatomic Au–Gd and Au–Sn interactions, while homoatomic Au–Au bonding is evident within the Au@Au6 clusters.« less

  15. Gold-rich R3Au7Sn3: Establishing the interdependence between electronic features and physical properties

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Provino, Alessia; Steinberg, Simon; Smetana, Volodymyr; Kulkarni, Ruta; Dhar, Sudesh K.; Manfrinetti, Pietro; Mudring, Anja -Verena

    2015-05-18

    Two new polar intermetallic compounds Y3Au7Sn3 (I) and Gd3Au7Sn3 (II) have been synthesized and their structures have been determined by single crystal X-ray diffraction (P63/m; Z = 2, a = 8.148(1)/8.185(3), and c = 9.394(2)/9.415(3) for I/II, respectively). They can formally be assigned to the Cu10Sn3 type and consist of parallel slabs of Sn centered, edge-sharing trigonal Au6 antiprisms connected through R3 (R = Y, Gd) triangles. Additional Au atoms reside in the centres of trigonal Au6 prisms forming Au@Au6 clusters with Au–Au distances of 2.906–2.960 Å, while the R–R contacts in the R3 groups are considerably larger than themore » sums of their metallic radii. These exclusive structural arrangements provide alluring systems to study the synergism between strongly correlated systems, particularly, those in the structure of (II), and extensive polar intermetallic contacts, which has been inspected by measurements of the magnetic properties, heat capacities and electrical conductivities of both compounds. Gd3Au7Sn3 shows an antiferromagnetic ordering at 13 K, while Y3Au7Sn3 is a Pauli paramagnet and a downward curvature in its electrical resistivity at about 1.9 K points to a superconducting transition. DFT-based band structure calculations on R3Au7Sn3 (R = Y, Gd) account for the results of the conductivity measurements and different spin ordering models of (II) provide conclusive hints about its magnetic structure. As a result, chemical bonding analyses of both compounds indicate that the vast majority of bonding originates from the heteroatomic Au–Gd and Au–Sn interactions, while homoatomic Au–Au bonding is evident within the Au@Au6 clusters.« less

  16. Photoactivation experiment on {sup 197}Au and its implications for the dipole strength in heavy nuclei

    SciTech Connect (OSTI)

    Nair, C.; Erhard, M.; Junghans, A. R.; Bemmerer, D.; Beyer, R.; Klug, J.; Kosev, K.; Rusev, G.; Schilling, K. D.; Schwengner, R.; Wagner, A.; Grosse, E.

    2008-11-15

    The {sup 197}Au({gamma},n) reaction is used as an activation standard for photodisintegration studies on astrophysically relevant nuclei. At the bremsstrahlung facility of the superconducting electron accelerator ELBE (Electron Linear accelerator of high Brilliance and low Emittance) of Forschungszentrum Dresden-Rossendorf, photoactivation measurements on {sup 197}Au have been performed with bremsstrahlung endpoint energies from 8.0 to 15.5 MeV. The measured activation yield is compared with previous experiments as well as with calculations using Hauser-Feshbach statistical models. It is shown that the experimental data are best described by a two-Lorentzian parametrization with taking the axial deformation of {sup 197}Au into account. The experimental {sup 197}Au({gamma},n) reaction yield measured at ELBE via the photoactivation method is found to be consistent with previous experimental data using photon scattering or neutron detection methods.

  17. Analysis of vapor-liquid-solid mechanism in Au-assisted GaAs nanowire growth

    SciTech Connect (OSTI)

    Harmand, J.C.; Patriarche, G.; Pere-Laperne, N.; Merat-Combes, M-N.; Travers, L.; Glas, F.

    2005-11-14

    GaAs nanowires were grown by molecular-beam epitaxy on (111)B oriented surfaces, after the deposition of Au nanoparticles. Different growth durations and different growth terminations were tested. After the growth of the nanowires, the structure and the composition of the metallic particles were analyzed by transmission electron microscopy and energy dispersive x-ray spectroscopy. We identified three different metallic compounds: the hexagonal {beta}{sup '}Au{sub 7}Ga{sub 2} structure, the orthorhombic AuGa structure, and an almost pure Au face centered cubic structure. We explain how these different solid phases are related to the growth history of the samples. It is concluded that during the wire growth, the metallic particles are liquid, in agreement with the generally accepted vapor-liquid-solid mechanism. In addition, the analysis of the wire morphology indicates that Ga adatoms migrate along the wire sidewalls with a mean length of about 3 {mu}m.

  18. Polarized proton parameters for the 2015 PP-on-Au setup in RHIC

    SciTech Connect (OSTI)

    Gardner, C. J.

    2015-08-25

    Values are given for RHIC circumference shifts due to snakes for various situations. Relevant parameters are tabulated for polarized protons (PP) in the booster and in AGS and RHIC for PP-on-Au stores.

  19. ARM Climate Modeling Best Estimate From Darwin, AU (ARMBE-ATM...

    Office of Scientific and Technical Information (OSTI)

    TWPC3) Title: ARM Climate Modeling Best Estimate From Darwin, AU (ARMBE-ATM TWPC3) The ARM CMBE-ATM Xie, McCoy, Klein et al. data file contains a best estimate of several ...

  20. ARM Climate Modeling Best Estimate From Darwin, AU (ARMBE-ATM...

    Office of Scientific and Technical Information (OSTI)

    TWPC2) Title: ARM Climate Modeling Best Estimate From Darwin, AU (ARMBE-ATM TWPC2) The ARM CMBE-ATM Xie, McCoy, Klein et al. data file contains a best estimate of several ...

  1. LAKESHORE AVON BR ANT-EDEN ALD EN-LANC ASTER AU BURN W SH ELDON

    U.S. Energy Information Administration (EIA) Indexed Site

    81 81 LAKESHORE AVON BR ANT-EDEN ALD EN-LANC ASTER AU BURN W SH ELDON CALEDONIA HURON C REEK LEIC EST ER COL DEN ASH FORD INDIAN FALLS LAWTONS SAR DINIA RPD-037 -2 ...

  2. Effect of growth temperature on ballistic electron transport through the Au/Si(001) interface

    SciTech Connect (OSTI)

    Eckes, M. W.; Friend, B. E.; Stollenwerk, A. J.

    2014-04-28

    Ballistic electron emission spectroscopy was used to investigate electron transport through Au/Si(001) Schottky diodes grown at 35?C and 22?C. Aside from a decreased Schottky height, this small increase in temperature introduced an energy dependent scattering component, which was absent in the samples grown at 22?C. These differences may be attributed to the increased amount of Au-Si intermixing at the interface. Despite the non-epitaxial nature of the growth technique, strong evidence was found in both sets of samples that indicated the presence of a forward-focused current subject to some degree of parallel momentum conservation at the interface. This evidence was present in all samples grown at 35?C, but was only observed in those samples grown at 22?C when the Au films were 10?nm or thicker. This sensitivity to growth temperature could account for discrepancies in previous studies on Au/Si(001)

  3. Measurement of J/ψ Azimuthal Anisotropy in Au+Au Collisions at √sNN=200 GeV

    SciTech Connect (OSTI)

    Adamczyk, L.; Adkins, J. K.; Agakishiev, G.; Aggarwal, M. M.; Ahammed, Z.; Alekseev, I.; Alford, J.; Anson, C. D.; Aparin, A.; Arkhipkin, D.; Aschenauer, E.; Averichev, G. S.; Balewski, J.; Banerjee, A.; Barnovska, Z.; Beavis, D. R.; Bellwied, R.; Betancourt, M. J.; Betts, R. R.; Bhasin, A.; Bhati, A. K.; Bhattarai, P.; Bichsel, H.; Bielcik, J.; Bielcikova, J.; Bland, L. C.; Bordyuzhin, I. G.; Borowski, W.; Bouchet, J.; Brandin, A. V.; Brovko, S. G.; Bruna, E.; Bültmann, S.; Bunzarov, I.; Burton, T. P.; Butterworth, J.; Cai, X. Z.; Caines, H.; Calderón de la Barca Sánchez, M.; Cebra, D.; Cendejas, R.; Cervantes, M. C.; Chaloupka, P.; Chang, Z.; Chattopadhyay, S.; Chen, H. F.; Chen, J. H.; Chen, J. Y.; Chen, L.; Cheng, J.; Cherney, M.; Chikanian, A.; Christie, W.; Chung, P.; Chwastowski, J.; Codrington, M. J. M.; Corliss, R.; Cramer, J. G.; Crawford, H. J.; Cui, X.; Das, S.; Davila Leyva, A.; De Silva, L. C.; Debbe, R. R.; Dedovich, T. G.; Deng, J.; Derradi de Souza, R.; Dhamija, S.; di Ruzza, B.; Didenko, L.; Ding, F.; Dion, A.; Djawotho, P.; Dong, X.; Drachenberg, J. L.; Draper, J. E.; Du, C. M.; Dunkelberger, L. E.; Dunlop, J. C.; Efimov, L. G.; Elnimr, M.; Engelage, J.; Eppley, G.; Eun, L.; Evdokimov, O.; Fatemi, R.; Fazio, S.; Fedorisin, J.; Fersch, R. G.; Filip, P.; Finch, E.; Fisyak, Y.; Flores, E.; Gagliardi, C. A.; Gangadharan, D. R.; Garand, D.; Geurts, F.; Gibson, A.; Gliske, S.; Grebenyuk, O. G.; Grosnick, D.; Gupta, A.; Gupta, S.; Guryn, W.; Haag, B.; Hajkova, O.; Hamed, A.; Han, L-X.; Harris, J. W.; Hays-Wehle, J. P.; Heppelmann, S.; Hirsch, A.; Hoffmann, G. W.; Hofman, D. J.; Horvat, S.; Huang, B.; Huang, H. Z.; Huck, P.; Humanic, T. J.; Igo, G.; Jacobs, W. W.; Jena, C.; Judd, E. G.; Kabana, S.; Kang, K.; Kapitan, J.; Kauder, K.; Ke, H. W.; Keane, D.; Kechechyan, A.; Kesich, A.; Kikola, D. P.; Kiryluk, J.; Kisel, I.; Kisiel, A.; Klein, S. R.; Koetke, D. D.; Kollegger, T.; Konzer, J.; Koralt, I.; Korsch, W.; Kotchenda, L.; Kravtsov, P.; Krueger, K.; Kulakov, I.; Kumar, L.; Lamont, M. A. C.; Landgraf, J. M.; Landry, K. D.; LaPointe, S.; Lauret, J.; Lebedev, A.; Lednicky, R.; Lee, J. H.; Leight, W.; LeVine, M. J.; Li, C.; Li, W.; Li, X.; Li, X.; Li, Y.; Li, Z. M.; Lima, L. M.; Lisa, M. A.; Liu, F.; Ljubicic, T.; Llope, W. J.; Longacre, R. S.; Lu, Y.; Luo, X.; Luszczak, A.; Ma, G. L.; Ma, Y. G.; Madagodagettige Don, D. M. M. D.; Mahapatra, D. P.; Majka, R.; Margetis, S.; Markert, C.; Masui, H.; Matis, H. S.; McDonald, D.; McShane, T. S.; Mioduszewski, S.; Mitrovski, M. K.; Mohammed, Y.; Mohanty, B.; Mondal, M. M.; Munhoz, M. G.; Mustafa, M. K.; Naglis, M.; Nandi, B. K.; Nasim, Md.; Nayak, T. K.; Nelson, J. M.; Nogach, L. V.; Novak, J.; Odyniec, G.; Ogawa, A.; Oh, K.; Ohlson, A.; Okorokov, V.; Oldag, E. W.; Oliveira, R. A. N.; Olson, D.; Pachr, M.; Page, B. S.; Pal, S. K.; Pan, Y. X.; Pandit, Y.; Panebratsev, Y.; Pawlak, T.; Pawlik, B.; Pei, H.; Perkins, C.; Peryt, W.; Pile, P.; Planinic, M.; Pluta, J.; Poljak, N.; Porter, J.; Poskanzer, A. M.; Powell, C. B.; Pruneau, C.; Pruthi, N. K.; Przybycien, M.; Pujahari, P. R.; Putschke, J.; Qiu, H.; Ramachandran, S.; Raniwala, R.; Raniwala, S.; Ray, R. L.; Riley, C. K.; Ritter, H. G.; Roberts, J. B.; Rogachevskiy, O. V.; Romero, J. L.; Ross, J. F.; Ruan, L.; Rusnak, J.; Sahoo, N. R.; Sahu, P. K.; Sakrejda, I.; Salur, S.; Sandacz, A.; Sandweiss, J.; Sangaline, E.; Sarkar, A.; Schambach, J.; Scharenberg, R. P.; Schmah, A. M.; Schmidke, B.; Schmitz, N.; Schuster, T. R.; Seger, J.; Seyboth, P.; Shah, N.; Shahaliev, E.; Shao, M.; Sharma, B.; Sharma, M.; Shi, S. S.; Shou, Q. Y.; Sichtermann, E. P.; Singaraju, R. N.; Skoby, M. J.; Smirnov, D.; Smirnov, N.; Solanki, D.; Sorensen, P.; deSouza, U. G.; Spinka, H. M.; Srivastava, B.; Stanislaus, T. D. S.; Stevens, J. R.; Stock, R.; Strikhanov, M.; Stringfellow, B.; Suaide, A. A. P.; Suarez, M. C.; Sumbera, M.; Sun, X. M.; Sun, Y.; Sun, Z.; Surrow, B.; Svirida, D. N.; Symons, T. J. M.; Szanto de Toledo, A.; Takahashi, J.; Tang, A. H.; Tang, Z.; Tarini, L. H.; Tarnowsky, T.; Thomas, J. H.; Tian, J.; Timmins, A. R.; Tlusty, D.; Tokarev, M.; Trentalange, S.; Tribble, R. E.; Tribedy, P.; Trzeciak, B. A.; Tsai, O. D.; Turnau, J.; Ullrich, T.; Underwood, D. G.; Van Buren, G.; van Nieuwenhuizen, G.; Vanfossen, J. A.; Varma, R.; Vasconcelos, G. M. S.; Videbæk, F.; Viyogi, Y. P.; Vokal, S.; Voloshin, S. A.; Vossen, A.; Wada, M.; Wang, F.; Wang, G.; Wang, H.; Wang, J. S.; Wang, Q.; Wang, X. L.; Wang, Y.; Webb, G.; Webb, J. C.; Westfall, G. D.; Whitten, C.; Wieman, H.; Wissink, S. W.; Witt, R.; Wu, Y. F.; Xiao, Z.; Xie, W.; Xin, K.; Xu, H.; Xu, N.; Xu, Q. H.; Xu, W.; Xu, Y.; Xu, Z.; Xue, L.; Yang, Y.; Yang, Y.; Yepes, P.; Yi, L.; Yip, K.; Yoo, I-K.; Zawisza, M.; Zbroszczyk, H.; Zhang, J. B.; Zhang, S.; Zhang, X. P.; Zhang, Y.; Zhang, Z. P.; Zhao, F.; Zhao, J.; Zhong, C.; Zhu, X.; Zhu, Y. H.; Zoulkarneeva, Y.; Zyzak, M.

    2013-08-02

    The measurement of J/ψ azimuthal anisotropy is presented as a function of transverse momentum for different centralities in Au+Au collisions at √sNN>/sub>=200 GeV. The measured J/ψ elliptic flow is consistent with zero within errors for transverse momentum between 2 and 10 GeV/c. Our measurement suggests that J/ψ particles with relatively large transverse momenta are not dominantly produced by coalescence from thermalized charm quarks, when comparing to model calculations.

  4. Measurement of J/ψ Azimuthal Anisotropy in Au+Au Collisions at √sNN=200 GeV

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Adamczyk, L.; Adkins, J. K.; Agakishiev, G.; Aggarwal, M. M.; Ahammed, Z.; Alekseev, I.; Alford, J.; Anson, C. D.; Aparin, A.; Arkhipkin, D.; et al

    2013-08-02

    The measurement of J/ψ azimuthal anisotropy is presented as a function of transverse momentum for different centralities in Au+Au collisions at √sNN>/sub>=200 GeV. The measured J/ψ elliptic flow is consistent with zero within errors for transverse momentum between 2 and 10 GeV/c. Our measurement suggests that J/ψ particles with relatively large transverse momenta are not dominantly produced by coalescence from thermalized charm quarks, when comparing to model calculations.

  5. Electronic Structure of Thiol-Covered Gold Nanoparticles: Au102(MBA)44 |

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Argonne Leadership Computing Facility Structure of Thiol-Covered Gold Nanoparticles: Au102(MBA)44 Authors: Li, Y., Galli, G., and Gygi, F. We present first principles, density functional theory (DFT) calculations of the structural and electronic properties of thiolate-protected gold nanoparticles [Au102(MBA)44 ] that have been recently crystallized and measured by X-ray diffraction. Our calculations yield structural properties in very good agreement with experiment and reveal the impact of

  6. Disassembly of hot nuclear matter formed in Au-induced reactions near the Fermi energy

    SciTech Connect (OSTI)

    Delis, D.N.

    1993-09-01

    Complex fragment emission has been studied in the 60 MeV/A {sup 197}Au + {sup 12}C, {sup 27}Al, {sup 51}V, {sup nat}Cu, and {sup 197}Au reactions. Velocity spectra, angular distributions and cross sections have been constructed for each target from the inclusive data. Coincidence data including 2-, 3-, 4-, and 5-fold events have also been examined. Furthermore neutron multiplicity distributions have been obtained for the above reactions by utilizing a novel neutron calorimetric approach.

  7. Synthesis, characterization and optical properties of hybrid PVAZnO nanocomposite: A composition dependent study

    SciTech Connect (OSTI)

    Hemalatha, K.S. [Department of Physics, Bangalore University, Bangalore 560 056, Karnataka (India); Department of Physics, Maharani's Science College for Women, Palace Road, Bangalore 560 001, Karnataka (India); Rukmani, K., E-mail: rukmani9909@yahoo.co.in [Department of Physics, Bangalore University, Bangalore 560 056, Karnataka (India); Suriyamurthy, N. [Radiological Safety Division, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102, Tamil Nadu (India); Nagabhushana, B.M. [Department of Chemistry, M.S. Ramaiah Institute of Technology, Bangalore 560 054, Karnataka (India)

    2014-03-01

    Graphical abstract: - Highlights: ZnO nanoparticles were prepared by solution combustion method. PVAZnO nanocomposites were synthesized by solution casting method. Doped and undoped films were characterized using different techniques. Red shift in optical band gap was observed in Nanocomposite films with respect to nano ZnO. Photoluminescence intensity was found to be optimum for PVA10 mol% ZnO nanocomposite film. - Abstract: Nanocomposites of poly vinyl alcohol (PVA) and ZnO have been synthesized using the solution casting technique for different concentrations of nano ZnO powder prepared by low temperature solution combustion method. The formation of polymer nanocomposite and changes in the structural and micro structural properties of the materials were investigated by X-ray diffraction, Energy dispersive X ray spectroscopy and optical microscopy techniques (FTIR and UVVisible). The surface morphology of PVAZnO nanocomposite films were elucidated using Scanning Electron Microscopy. The optical absorption spectrum of nano ZnO shows blue shift in the optical band gap energy with respect to characteristic bulk ZnO at room temperature, whereas PVAZnO hybrid films show red shift with respect to nano ZnO. The photoluminescence studies show that the intensity of the blue emission (470 nm) varies with change in concentration of ZnO with an optimum intensity observed at 10 mol% of ZnO.

  8. Electronic structure and vibrational entropies of fcc Au-Fe alloys

    SciTech Connect (OSTI)

    Munoz, Jorge A.; Lucas, Matthew; Mauger, L; Halevy, I; Horwath, J; Semiatin, S L; Xiao, Yuming; Stone, Matthew B; Abernathy, Douglas L; Fultz, B.

    2013-01-01

    Phonon density of states (DOS) curves were measured on alloys of face-centered-cubic (fcc) Au-Fe using nuclear resonant inelastic x-ray scattering (NRIXS) and inelastic neutron scattering (INS). The NRIXS and INS results were combined to obtain the total phonon DOS and the partial phonon DOS curves of Au and Fe atoms. The 57Fe partial phonon DOS of the dilute alloy Au0.97 57Fe0.03 shows a localized mode centered 4.3% above the cutoff energy of the phonons in pure Au. The Mannheim model for impurity modes accurately reproduced this partial phonon DOS using the fcc Au phonon DOS with a ratio of host-host to impurity-host force constants of 1.55. First-principles calculations validated the assumption of first-nearest-neighbor forces in the Mannheim model and gave a similar ratio of force constants. The high energy local mode broadens with increasing Fe composition, but this has a small effect on the composition dependence of the vibrational entropy. The main effect on the vibrational entropy of alloying comes from a stiffening of the Au partial phonon DOS with Fe concentration. This stiffening is attributed to two main effects: 1) an increase in electron density in the free-electron-like states, and 2) stronger sd-hybridization. These two effects are comparable in magnitude.

  9. Stability of Surface and Subsurface Hydrogen on and in Au/Ni Near-Surface Alloys

    SciTech Connect (OSTI)

    Celik, Fuat E.; Mavrikakis, Manos

    2015-10-01

    Periodic, self-consistent DFT-GGA (PW91) calculations were used to study the interaction of hydrogen atoms with the (111) surfaces of substitutional near-surface alloys (NSAs) of Au and Ni with different surface layer compositions and different arrangements of Au atoms in the surface layer. The effect of hydrogen adsorption on the surface and in the first and second subsurface layers of the NSAs was studied. Increasing the Au content in the surface layer weakens hydrogen binding on the surface, but strengthens subsurface binding, suggesting that the distribution of surface and subsurface hydrogen will be different than that on pure Ni(111). While the metal composition of the surface layer has an effect on the binding energy of hydrogen on NSA surfaces, the local composition of the binding site has a stronger effect. For example, fcc hollow sites consisting of three Ni atoms bind H nearly as strongly as on Ni(111), and fcc sites consisting of three Au atoms bind H nearly as weakly as on Au(111). Sites with one or two Au atoms show intermediate binding energies. The preference of hydrogen for three-fold Ni hollow sites alters the relative stabilities of different surface metal atom arrangements, and may provide a driving force for adsorbate-induced surface rearrangement.

  10. Bond-bending isomerism of Au2I3-: Competition between covalent bonding and aurophilicity

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Li, Wan -Lu; Liu, Hong -Tao; Jian, Tian; Lopez, Gary V.; Piazza, Zachary A.; Huang, Dao -Ling; Chen, Teng -Teng; Su, Jing; Yang, Ping; Chen, Xin; et al

    2015-10-13

    We report a joint photoelectron spectroscopy and theoretical investigation of the gaseous Au2I3– cluster, which is found to exhibit two types of isomers due to competition between Au–I covalent bonding and Au–Au aurophilic interactions. The covalent bonding favors a bent IAuIAuI– structure with an obtuse Au–I–Au angle (100.7°), while aurophilic interactions pull the two Au atoms much closer, leading to an acutely bent structure (72.0°) with an Au–Au distance of 3.08 Å. The two isomers are separated by a small barrier and are nearly degenerate with the obtuse isomer being slightly more stable. At low temperature, only the obtuse isomermore » is observed; distinct experimental evidence is observed for the co-existence of a combination of isomers with both acute and obtuse bending angles at room temperature. As a result, the two bond-bending isomers of Au2I3– reveal a unique example of one molecule being able to oscillate between different structures as a result of two competing chemical forces.« less

  11. Thickness Effect of Al-Doped ZnO Window Layer on Damp Heat Stability of CuInGaSe2 Solar Cells: Preprint

    SciTech Connect (OSTI)

    Pern, F. J.; Mansfield, L.; DeHart, C.; Glick, S. H.; Yan, F.; Noufi, R.

    2011-07-01

    We investigated the damp heat (DH) stability of CuInGaSe2 (CIGS) solar cells as a function of thickness of the Al-doped ZnO (AZO) window layer from the 'standard' 0.12 μm to a modest 0.50 μm over an underlying 0.10-μm intrinsic ZnO buffer layer. The CIGS cells were prepared with external electrical contact using fine Au wire to the tiny 'standard' Ni/Al (0.05 μm/3 μm) metal grid contact pads. Bare cell coupons and sample sets encapsulated in a specially designed, Al-frame test structure with an opening for moisture ingress control using a TPT backsheet were exposed to DH at 85oC and 85% relative humidity, and characterized by current-voltage (I-V), quantum efficiency (QE), and (electrochemical) impedance spectroscopy (ECIS). The results show that bare cells exhibited rapid degradation within 50-100 h, accompanied by film wrinkling and delamination and corrosion of Mo and AlNi grid, regardless of AZO thickness. In contrast, the encapsulated cells did not show film wrinkling, delamination, and Mo corrosion after 168 h DH exposure; but the trend of efficiency degradation rate showed a weak correlation to the AZO thickness.

  12. Thickness Effect of Al-Doped ZnO Window Layer on Damp-Heat Stability of CuInGaSe2 Solar Cells

    SciTech Connect (OSTI)

    Pern, F. J.; Mansfield, L.; DeHart, C.; Glick, S. H.; Yan, F.; Noufi, R.

    2011-01-01

    We investigated the damp heat (DH) stability of CuInGaSe{sub 2} (CIGS) solar cells as a function of thickness of the Al-doped ZnO (AZO) window layer from the 'standard' 0.12 {micro}m to a modest 0.50 {micro}m over an underlying 0.10-{micro}m intrinsic ZnO buffer layer. The CIGS cells were prepared with external electrical contact using fine Au wire to the tiny 'standard' Ni/Al (0.05 {micro}m/3 {micro}m) metal grid contact pads. Bare cell coupons and sample sets encapsulated in a specially designed, Al-frame test structure with an opening for moisture ingress control using a TPT backsheet were exposed to DH at 85 C and 85% relative humidity, and characterized by current-voltage (I-V), quantum efficiency (QE), and (electrochemical) impedance spectroscopy (ECIS). The results show that bare cells exhibited rapid degradation within 50-100 h, accompanied by film wrinkling and delamination and corrosion of Mo and AlNi grid, regardless of AZO thickness. In contrast, the encapsulated cells did not show film wrinkling, delamination, and Mo corrosion after 168 h DH exposure; but the trend of efficiency degradation rate showed a weak correlation to the AZO thickness.

  13. Low dark current and high speed ZnO metalsemiconductormetal photodetector on SiO{sub 2}/Si substrate

    SciTech Connect (OSTI)

    al??kan, Deniz; Btn, Bayram; ak?r, M. Cihan; zcan, ?adan; zbay, Ekmel

    2014-10-20

    ZnO thin films are deposited by radio-frequency magnetron sputtering on thermally grown SiO{sub 2} on Si substrates. Pt/Au contacts are fabricated by standard photolithography and lift-off in order to form a metal-semiconductor-metal (MSM) photodetector. The dark current of the photodetector is measured as 1?pA at 100?V bias, corresponding to 100?pA/cm{sup 2} current density. Spectral photoresponse measurement showed the usual spectral behavior and 0.35?A/W responsivity at a 100?V bias. The rise and fall times for the photocurrent are measured as 22 ps and 8?ns, respectively, which are the lowest values to date. Scanning electron microscope image shows high aspect ratio and dense grains indicating high surface area. Low dark current density and high speed response are attributed to high number of recombination centers due to film morphology, deducing from photoluminescence measurements. These results show that as deposited ZnO thin film MSM photodetectors can be used for the applications needed for low light level detection and fast operation.

  14. High mobility ZnO nanowires for terahertz detection applications

    SciTech Connect (OSTI)

    Liu, Huiqiang; Peng, Rufang E-mail: chusheng@mail.sysu.edu.cn; Chu, Shijin; Chu, Sheng E-mail: chusheng@mail.sysu.edu.cn

    2014-07-28

    An oxide nanowire material was utilized for terahertz detection purpose. High quality ZnO nanowires were synthesized and field-effect transistors were fabricated. Electrical transport measurements demonstrated the nanowire with good transfer characteristics and fairly high electron mobility. It is shown that ZnO nanowires can be used as building blocks for the realization of terahertz detectors based on a one-dimensional plasmon detection configuration. Clear terahertz wave (∼0.3 THz) induced photovoltages were obtained at room temperature with varying incidence intensities. Further analysis showed that the terahertz photoresponse is closely related to the high electron mobility of the ZnO nanowire sample, which suggests that oxide nanoelectronics may find useful terahertz applications.

  15. Nitrogen is a deep acceptor in ZnO

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Tarun, M. C.; Iqbal, M. Zafar; McCluskey, M. D.

    2011-04-14

    Zinc oxide is a promising material for blue and UV solid-state lighting devices, among other applications. Nitrogen has been regarded as a potential p-type dopant for ZnO. However, recent calculations indicate that nitrogen is a deep acceptor. This paper presents experimental evidence that nitrogen is, in fact, a deep acceptor and therefore cannot produce p-type ZnO. A broad photoluminescence (PL) emission band near 1.7 eV, with an excitation onset of ~2.2 eV, was observed, in agreement with the deep-acceptor model of the nitrogen defect. Thus the deep-acceptor behavior can be explained by the low energy of the ZnO valence bandmore » relative to the vacuum level.« less

  16. Process for fabricating ZnO-based varistors

    DOE Patents [OSTI]

    Lauf, Robert J.

    1985-01-01

    The invention is a process for producing ZnO-based varistors incorporating a metal oxide dopant. In one form, the invention comprises providing a varistor powder mix of colloidal particles of ZnO and metal-oxide dopants including Bi.sub.2 O.sub.3. The mix is hot-pressed to form a compact at temperatures below 850.degree. C. and under conditions effecting reduction of the ZnO to sub-stoichiometric oxide. This promotes densification while restricting liquid formation and grain growth. The compact then is heated under conditions restoring the zinc oxide to stoichiometric composition, thus improving the varistor properties of the compact. The process produces fine-grain varistors characterized by a high actual breakdown voltage and a high average breakdown voltage per individual grain boundary.

  17. Process for fabricating ZnO-based varistors

    DOE Patents [OSTI]

    Lauf, R.J.

    The invention is a process for producing ZnO-based varistors incorporating a metal oxide dopant. In one form, the invention comprises providing a varistor powder mix of colloidal particles of ZnO and metal-oxide dopants including Bi/sub 2/O/sub 3/. The mix is hot-pressed to form a compact at temperatures below 850/sup 0/C and under conditions effecting reduction of the ZnO to sub-stoichiometric oxide. This promotes densification while restricting liquid formation and grain growth. The compact then is heated under conditions restoring the zinc oxide to stoichiometric composition, thus improving the varistor properties of the compact. The process produces fine-grain varistors characterized by a high actual breakdown voltage and a high average breakdown voltage per individual grain boundary.

  18. Enhanced photoelectrochemical responses of ZnO films through Ga and N codoping

    SciTech Connect (OSTI)

    Ahn, Kwang-Soon; Yan, Yanfa; Shet, Sudhakar; Deutsch, Todd; Turner, John; Al-Jassim, Mowafak

    2007-12-03

    We report on the crystallinity and photoelectrochemical (PEC) response of ZnO thin films codoped by Ga and N. The ZnO:(Ga,N) thin films were deposited by cosputtering at room temperature and followed by postannealing at 500 deg. C in air for 2 h. We found that ZnO:(Ga,N) thin films exhibited significantly enhanced crystallinity compared to ZnO doped solely with N at the same growth conditions. Furthermore, ZnO:(Ga,N) thin films exhibited enhanced N incorporation over ZnO doped solely with N at high temperatures. As a result, ZnO:(Ga,N) thin films achieved dramatically improved PEC response, compared to ZnO thin films doped solely with N at any conditions. Our results suggest a general way to improve PEC response for wide-band-gap oxides.

  19. A Reversible Structural Phase Transition in ZnV2O6 at High Pressures...

    Office of Scientific and Technical Information (OSTI)

    A Reversible Structural Phase Transition in ZnV2O6 at High Pressures Citation Details In-Document Search Title: A Reversible Structural Phase Transition in ZnV2O6 at High Pressures ...

  20. Luminescent properties of solution-grown ZnO nanorods. (Journal...

    Office of Scientific and Technical Information (OSTI)

    Luminescent properties of solution-grown ZnO nanorods. Citation Details In-Document Search Title: Luminescent properties of solution-grown ZnO nanorods. The optical properties of ...

  1. Local structures of copper-doped ZnO films (Journal Article)...

    Office of Scientific and Technical Information (OSTI)

    Local structures of copper-doped ZnO films Citation Details In-Document Search Title: Local structures of copper-doped ZnO films Authors: Ma, Q. ; Buchholz, D.B. ; Chang, R.P.H. ...

  2. One-step electrochemical synthesis of a grapheneZnO hybrid for improved photocatalytic activity

    SciTech Connect (OSTI)

    Wei, Ang; Xiong, Li; Sun, Li; Liu, Yanjun; Li, Weiwei; Lai, Wenyong; Liu, Xiangmei; Wang, Lianhui; Huang, Wei; Dong, Xiaochen

    2013-08-01

    Graphical abstract: - Highlights: GrapheneZnO hybrid was synthesized by one-step electrochemical deposition. GrapheneZnO hybrid presents a special structure and wide UVvis absorption spectra. GrapheneZnO hybrid exhibits an exceptionally higher photocatalytic activity for the degradation of dye methylene blue. - Abstract: A grapheneZnO (G-ZnO) hybrid was synthesized by one-step electrochemical deposition. During the formation of ZnO nanostructure by cathodic electrochemical deposition, the graphene oxide was electrochemically reduced to graphene simultaneously. Scanning electron microscope images, X-ray photoelectron spectroscopy, X-ray diffraction, Raman spectra, and UVvis absorption spectra indicate the resulting G-ZnO hybrid presents a special structure and wide UVvis absorption spectra. More importantly, it exhibits an exceptionally higher photocatalytic activity for the degradation of dye methylene blue than that of pure ZnO nanostructure under both ultraviolet and sunlight irradiation.

  3. Classification of Lattice Defects in the Kesterite Cu2ZnSnS4...

    Office of Scientific and Technical Information (OSTI)

    Journal Article: Classification of Lattice Defects in the Kesterite Cu2ZnSnS4 and Cu2ZnSnSe4 Earth-Abundant Solar Cell Absorbers Citation Details In-Document Search Title: ...

  4. Phases in the Al-Yb-Zn system between 25 and 50 at% ytterbium...

    Office of Scientific and Technical Information (OSTI)

    the Al-Yb-Zn system between 25 and 50 at% ytterbium Citation Details In-Document Search Title: Phases in the Al-Yb-Zn system between 25 and 50 at% ytterbium Phases YbZnsub ...

  5. Nucleon-gold collisions at 200A GeV using tagged d + Au interactions in the PHOBOS detector

    SciTech Connect (OSTI)

    Back, B. B.; Nouicer, R.; Baker, M. D.; Ballintijn, M.; Barton, D. S.; Becker, B.; Betts, R. R.; Bickley, A. A; Stienberg, P.; Ioradnova, A.; Pak, R.; Sukhanov, A.

    2015-09-23

    Forward calorimetry in the PHOBOS detector has been used to study charged hadron production in d+Au, p+Au, and n+Au collisions at √sNN =200GeV. The forward proton calorimeter detectors are described and a procedure for determining collision centrality with these detectors is detailed. The deposition of energy by deuteron spectator nucleons in the forward calorimeters is used to identify p+Au and n+Au collisions in the data. A weighted combination of the yield of p+Au and n+Au is constructed to build a reference for Au+Au collisions that better matches the isospin composition of the gold nucleus. The pT and centrality dependence of the yield of this improved reference system is found to match that of d+Au. The shape of the charged-particle transverse momentum distribution is observed to extrapolate smoothly from p+p¯ to central d+Au as a function of the charged-particle pseudorapidity density. The asymmetry of positively and negatively charged hadron production in p+Au is compared to that of n+Au. No significant asymmetry is observed at midrapidity. In conclusion, these studies augment recent results from experiments at the CERN Large Hadron Collider and BNL Relativistic Heavy Ion Collider facilities to give a more complete description of particle production in p+A and d+A collisions, essential for the understanding the medium produced in high-energy nucleus-nucleus collisions.

  6. Nucleon-gold collisions at 200A GeV using tagged d + Au interactions in the PHOBOS detector

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Back, B. B.; Nouicer, R.; Baker, M. D.; Ballintijn, M.; Barton, D. S.; Becker, B.; Betts, R. R.; Bickley, A. A; Stienberg, P.; Ioradnova, A.; et al

    2015-09-23

    Forward calorimetry in the PHOBOS detector has been used to study charged hadron production in d+Au, p+Au, and n+Au collisions at √sNN =200GeV. The forward proton calorimeter detectors are described and a procedure for determining collision centrality with these detectors is detailed. The deposition of energy by deuteron spectator nucleons in the forward calorimeters is used to identify p+Au and n+Au collisions in the data. A weighted combination of the yield of p+Au and n+Au is constructed to build a reference for Au+Au collisions that better matches the isospin composition of the gold nucleus. The pT and centrality dependence ofmore » the yield of this improved reference system is found to match that of d+Au. The shape of the charged-particle transverse momentum distribution is observed to extrapolate smoothly from p+p¯ to central d+Au as a function of the charged-particle pseudorapidity density. The asymmetry of positively and negatively charged hadron production in p+Au is compared to that of n+Au. No significant asymmetry is observed at midrapidity. In conclusion, these studies augment recent results from experiments at the CERN Large Hadron Collider and BNL Relativistic Heavy Ion Collider facilities to give a more complete description of particle production in p+A and d+A collisions, essential for the understanding the medium produced in high-energy nucleus-nucleus collisions.« less

  7. Measurement of Υ(1S + 2S +3S) production in p + p and Au + Au collisions at \\(\\sqrt{s_{\\mathrm{NN}}}=200\\) GeV

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Adare, A.; Afanasiev, S.; Aidala, C.; Ajitanand, N. N.; Akiba, Y.; Akimoto, R.; Al-Bataineh, H.; Al-Ta'ani, H.; Alexander, J.; Angerami, A.; et al

    2015-02-24

    Measurements of bottomonium production in heavy-ion and p+p collisions at the Relativistic Heavy Ion Collider (RHIC) are presented. The inclusive yield of the three Υ states, Υ(1S + 2S + 3S), was measured in the PHENIX experiment via electron-positron decay pairs at midrapidity for Au+Au and p+p collisions at \\(\\sqrt{s_{\\mathrm{NN}}}=200\\) GeV. The Υ(1S + 2S + 3S) → e⁺e⁻ differential cross section at midrapidity was found to be Beedσ/dy = 108 ± 38 (stat) ± 15 (syst) ± 11 (luminosity) pb in p+p collisions. The nuclear modification factor in the 30% most central Au+Au collisions indicates a suppression of themore »total Υ state yield relative to the extrapolation from p+p collision data. Thus, the suppression is consistent with measurements at higher energies by the CMS experiment at the Large Hadron Collider.« less

  8. Measurement of Υ(1S + 2S +3S) production in p + p and Au + Au collisions at \\(\\sqrt{s_{\\mathrm{NN}}}=200\\) GeV

    SciTech Connect (OSTI)

    Adare, A.; Afanasiev, S.; Aidala, C.; Ajitanand, N. N.; Akiba, Y.; Akimoto, R.; Al-Bataineh, H.; Al-Ta'ani, H.; Alexander, J.; Angerami, A.; Aoki, K.; Apadula, N.; Aphecetche, L.; Aramaki, Y.; Asai, J.; Asano, H.; Aschenauer, E. C.; Atomssa, E. T.; Averbeck, R.; Awes, T. C.; Azmoun, B.; Babintsev, V.; Bai, M.; Baksay, G.; Baksay, L.; Baldisseri, A.; Bannier, B.; Barish, K. N.; Barnes, P. D.; Bassalleck, B.; Basye, A. T.; Bathe, S.; Batsouli, S.; Baublis, V.; Baumann, C.; Baumgart, S.; Bazilevsky, A.; Belikov, S.; Belmont, R.; Bennett, R.; Berdnikov, A.; Berdnikov, Y.; Bickley, A. A.; Bing, X.; Blau, D. S.; Boissevain, J. G.; Bok, J. S.; Borel, H.; Boyle, K.; Brooks, M. L.; Buesching, H.; Bumazhnov, V.; Bunce, G.; Butsyk, S.; Camacho, C. M.; Campbell, S.; Castera, P.; Chang, B. S.; Chang, W. C.; Charvet, J. -L.; Chen, C. -H.; Chernichenko, S.; Chi, C. Y.; Chiu, M.; Choi, I. J.; Choi, J. B.; Choi, S.; Choudhury, R. K.; Christiansen, P.; Chujo, T.; Chung, P.; Churyn, A.; Chvala, O.; Cianciolo, V.; Citron, Z.; Cole, B. A.; Connors, M.; Constantin, P.; Csanád, M.; Csörgő, T.; Dahms, T.; Dairaku, S.; Das, K.; Datta, A.; Daugherity, M. S.; David, G.; Denisov, A.; d'Enterria, D.; Deshpande, A.; Desmond, E. J.; Dharmawardane, K. V.; Dietzsch, O.; Ding, L.; Dion, A.; Donadelli, M.; Drapier, O.; Drees, A.; Drees, K. A.; Dubey, A. K.; Durham, J. M.; Durum, A.; Dutta, D.; Dzhordzhadze, V.; D'Orazio, L.; Edwards, S.; Efremenko, Y. V.; Ellinghaus, F.; Engelmore, T.; Enokizono, A.; En'yo, H.; Esumi, S.; Eyser, K. O.; Fadem, B.; Fields, D. E.; Finger, M.; Finger, M.; Fleuret, F.; Fokin, S. L.; Fraenkel, Z.; Frantz, J. E.; Franz, A.; Frawley, A. D.; Fujiwara, K.; Fukao, Y.; Fusayasu, T.; Gainey, K.; Gal, C.; Garishvili, A.; Garishvili, I.; Glenn, A.; Gong, H.; Gong, X.; Gonin, M.; Gosset, J.; Goto, Y.; Granier de Cassagnac, R.; Grau, N.; Greene, S. V.; Grosse Perdekamp, M.; Gunji, T.; Guo, L.; Gustafsson, H. -Å.; Hachiya, T.; Hadj Henni, A.; Haggerty, J. S.; Hahn, K. I.; Hamagaki, H.; Han, R.; Hanks, J.; Hartouni, E. P.; Haruna, K.; Hashimoto, K.; Haslum, E.; Hayano, R.; He, X.; Heffner, M.; Hemmick, T. K.; Hester, T.; Hill, J. C.; Hohlmann, M.; Hollis, R. S.; Holzmann, W.; Homma, K.; Hong, B.; Horaguchi, T.; Hori, Y.; Hornback, D.; Huang, S.; Ichihara, T.; Ichimiya, R.; Iinuma, H.; Ikeda, Y.; Imai, K.; Imrek, J.; Inaba, M.; Iordanova, A.; Isenhower, D.; Ishihara, M.; Isobe, T.; Issah, M.; Isupov, A.; Ivanischev, D.; Ivanishchev, D.; Jacak, B. V.; Javani, M.; Jia, J.; Jiang, X.; Jin, J.; Johnson, B. M.; Joo, K. S.; Jouan, D.; Jumper, D. S.; Kajihara, F.; Kametani, S.; Kamihara, N.; Kamin, J.; Kaneti, S.; Kang, B. H.; Kang, J. H.; Kang, J. S.; Kapustinsky, J.; Karatsu, K.; Kasai, M.; Kawall, D.; Kazantsev, A. V.; Kempel, T.; Khanzadeev, A.; Kijima, K. M.; Kikuchi, J.; Kim, B. I.; Kim, C.; Kim, D. H.; Kim, D. J.; Kim, E.; Kim, E. -J.; Kim, H. J.; Kim, K. -B.; Kim, S. H.; Kim, Y. -J.; Kim, Y. K.; Kinney, E.; Kiriluk, K.; Kiss, Á.; Kistenev, E.; Klatsky, J.; Klay, J.; Klein-Boesing, C.; Kleinjan, D.; Kline, P.; Kochenda, L.; Komatsu, Y.; Komkov, B.; Konno, M.; Koster, J.; Kotchetkov, D.; Kotov, D.; Kozlov, A.; Král, A.; Kravitz, A.; Krizek, F.; Kunde, G. J.; Kurita, K.; Kurosawa, M.; Kweon, M. J.; Kwon, Y.; Kyle, G. S.; Lacey, R.; Lai, Y. S.; Lajoie, J. G.; Layton, D.; Lebedev, A.; Lee, B.; Lee, D. M.; Lee, J.; Lee, K. B.; Lee, K. S.; Lee, S. H.; Lee, S. R.; Lee, T.; Leitch, M. J.; Leite, M. A. L.; Leitgab, M.; Lenzi, B.; Lewis, B.; Li, X.; Liebing, P.; Lim, S. H.; Linden Levy, L. A.; Liška, T.; Litvinenko, A.; Liu, H.; Liu, M. X.; Love, B.; Lynch, D.; Maguire, C. F.; Makdisi, Y. I.; Makek, M.; Malakhov, A.; Malik, M. D.; Manion, A.; Manko, V. I.; Mannel, E.; Mao, Y.; Mašek, L.; Masui, H.; Masumoto, S.; Matathias, F.; McCumber, M.; McGaughey, P. L.; McGlinchey, D.; McKinney, C.; Means, N.; Mendoza, M.; Meredith, B.; Miake, Y.; Mibe, T.; Mignerey, A. C.; Mikeš, P.; Miki, K.; Milov, A.; Mishra, D. K.; Mishra, M.; Mitchell, J. T.; Miyachi, Y.; Miyasaka, S.; Mohanty, A. K.; Moon, H. J.; Morino, Y.; Morreale, A.; Morrison, D. P.; Motschwiller, S.; Moukhanova, T. V.; Mukhopadhyay, D.; Murakami, T.; Murata, J.; Nagae, T.; Nagamiya, S.; Nagle, J. L.; Naglis, M.; Nagy, M. I.; Nakagawa, I.; Nakamiya, Y.; Nakamura, K. R.; Nakamura, T.; Nakano, K.; Nattrass, C.; Nederlof, A.; Newby, J.; Nguyen, M.; Nihashi, M.; Niida, T.; Nouicer, R.; Novitzky, N.; Nyanin, A. S.; O'Brien, E.; Oda, S. X.; Ogilvie, C. A.; Oka, M.; Okada, K.; Onuki, Y.; Oskarsson, A.; Ouchida, M.; Ozawa, K.; Pak, R.; Palounek, A. P. T.; Pantuev, V.; Papavassiliou, V.; Park, B. H.; Park, I. H.; Park, J.; Park, S. K.; Park, W. J.; Pate, S. F.; Patel, L.; Pei, H.; Peng, J. -C.; Pereira, H.; Peresedov, V.; Peressounko, D. Yu.; Petti, R.; Pinkenburg, C.; Pisani, R. P.; Proissl, M.; Purschke, M. L.; Purwar, A. K.; Qu, H.; Rak, J.; Rakotozafindrabe, A.; Ravinovich, I.; Read, K. F.; Rembeczki, S.; Reygers, K.; Reynolds, D.; Riabov, V.; Riabov, Y.; Richardson, E.; Riveli, N.; Roach, D.; Roche, G.; Rolnick, S. D.; Rosati, M.; Rosendahl, S. S. E.; Rosnet, P.; Rukoyatkin, P.; Ružička, P.; Rykov, V. L.; Sahlmueller, B.; Saito, N.; Sakaguchi, T.; Sakai, S.; Sakashita, K.; Samsonov, V.; Sano, M.; Sarsour, M.; Sato, T.; Sawada, S.; Sedgwick, K.; Seele, J.; Seidl, R.; Semenov, A. Yu.; Semenov, V.; Sen, A.; Seto, R.; Sharma, D.; Shein, I.; Shibata, T. -A.; Shigaki, K.; Shimomura, M.; Shoji, K.; Shukla, P.; Sickles, A.; Silva, C. L.; Silvermyr, D.; Silvestre, C.; Sim, K. S.; Singh, B. K.; Singh, C. P.; Singh, V.; Slunečka, M.; Soldatov, A.; Soltz, R. A.; Sondheim, W. E.; Sorensen, S. P.; Soumya, M.; Sourikova, I. V.; Staley, F.; Stankus, P. W.; Stenlund, E.; Stepanov, M.; Ster, A.; Stoll, S. P.; Sugitate, T.; Suire, C.; Sukhanov, A.; Sun, J.; Sziklai, J.; Takagui, E. M.; Takahara, A.; Taketani, A.; Tanabe, R.; Tanaka, Y.; Taneja, S.; Tanida, K.; Tannenbaum, M. J.; Tarafdar, S.; Taranenko, A.; Tarján, P.; Tennant, E.; Themann, H.; Thomas, T. L.; Todoroki, T.; Togawa, M.; Toia, A.; Tomášek, L.; Tomášek, M.; Tomita, Y.; Torii, H.; Towell, R. S.; Tram, V-N.; Tserruya, I.; Tsuchimoto, Y.; Tsuji, T.; Vale, C.; Valle, H.; van Hecke, H. W.; Vargyas, M.; Vazquez-Zambrano, E.; Veicht, A.; Velkovska, J.; Vértesi, R.; Vinogradov, A. A.; Virius, M.; Vossen, A.; Vrba, V.; Vznuzdaev, E.; Wang, X. R.; Watanabe, D.; Watanabe, K.; Watanabe, Y.; Watanabe, Y. S.; Wei, F.; Wei, R.; Wessels, J.; Whitaker, S.; White, S. N.; Winter, D.; Wolin, S.; Woody, C. L.; Wysocki, M.; Xie, W.; Yamaguchi, Y. L.; Yamaura, K.; Yang, R.; Yanovich, A.; Ying, J.; Yokkaichi, S.; You, Z.; Young, G. R.; Younus, I.; Yushmanov, I. E.; Zajc, W. A.; Zaudtke, O.; Zelenski, A.; Zhang, C.; Zhou, S.; Zolin, L.

    2015-02-24

    Measurements of bottomonium production in heavy-ion and p+p collisions at the Relativistic Heavy Ion Collider (RHIC) are presented. The inclusive yield of the three Υ states, Υ(1S + 2S + 3S), was measured in the PHENIX experiment via electron-positron decay pairs at midrapidity for Au+Au and p+p collisions at \\(\\sqrt{s_{\\mathrm{NN}}}=200\\) GeV. The Υ(1S + 2S + 3S) → e⁺e⁻ differential cross section at midrapidity was found to be Beedσ/dy = 108 ± 38 (stat) ± 15 (syst) ± 11 (luminosity) pb in p+p collisions. The nuclear modification factor in the 30% most central Au+Au collisions indicates a suppression of the total Υ state yield relative to the extrapolation from p+p collision data. Thus, the suppression is consistent with measurements at higher energies by the CMS experiment at the Large Hadron Collider.

  9. Energy dependence of Kπ, pπ and Kp fluctuations in Au+Au collisions from √sNN=7.7 to 200 GeV

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Adamczyk, L.

    2015-08-07

    A search for the quantum chromodynamics (QCD) critical point was performed by the STAR experiment at the Relativistic Heavy Ion Collider, using dynamical fluctuations of unlike particle pairs. Heavy ion collisions were studied over a large range of collision energies with homogeneous acceptance and excellent particle identification, covering a significant range in the QCD phase diagram where a critical point may be located. Dynamical Kπ, pπ, and Kp fluctuations as measured by the STAR experiment in central 0–5% Au+Au collisions from center-of-mass collision energies √sNN=7.7 to 200 GeV are presented. The observable νdyn was used to quantify the magnitude ofmore » the dynamical fluctuations in event-by-event measurements of the Kπ, pπ, and Kp pairs. The energy dependences of these fluctuations from central 0–5% Au+Au collisions all demonstrate a smooth evolution with collision energy.« less

  10. Measurement of Υ(1S + 2S +3S) production in p + p and Au + Au collisions at \\(\\sqrt{s_{\\mathrm{NN}}}=200\\) GeV

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Adare, A.; Afanasiev, S.; Aidala, C.; Ajitanand, N. N.; Akiba, Y.; Akimoto, R.; Al-Bataineh, H.; Al-Ta'ani, H.; Alexander, J.; Angerami, A.; et al

    2015-02-24

    Measurements of bottomonium production in heavy-ion and p+p collisions at the Relativistic Heavy Ion Collider (RHIC) are presented. The inclusive yield of the three Υ states, Υ(1S + 2S + 3S), was measured in the PHENIX experiment via electron-positron decay pairs at midrapidity for Au+Au and p+p collisions at \\(\\sqrt{s_{\\mathrm{NN}}}=200\\) GeV. The Υ(1S + 2S + 3S) → e⁺e⁻ differential cross section at midrapidity was found to be Beedσ/dy = 108 ± 38 (stat) ± 15 (syst) ± 11 (luminosity) pb in p+p collisions. The nuclear modification factor in the 30% most central Au+Au collisions indicates a suppression of themore » total Υ state yield relative to the extrapolation from p+p collision data. Thus, the suppression is consistent with measurements at higher energies by the CMS experiment at the Large Hadron Collider.« less

  11. Energy dependence of Kπ, pπ and Kp fluctuations in Au+Au collisions from √sNN=7.7 to 200 GeV

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Adamczyk, L.

    2015-08-07

    A search for the quantum chromodynamics (QCD) critical point was performed by the STAR experiment at the Relativistic Heavy Ion Collider, using dynamical fluctuations of unlike particle pairs. Heavy ion collisions were studied over a large range of collision energies with homogeneous acceptance and excellent particle identification, covering a significant range in the QCD phase diagram where a critical point may be located. Dynamical Kπ, pπ, and Kp fluctuations as measured by the STAR experiment in central 0–5% Au+Au collisions from center-of-mass collision energies √sNN=7.7 to 200 GeV are presented. The observable νdyn was used to quantify the magnitude ofmore »the dynamical fluctuations in event-by-event measurements of the Kπ, pπ, and Kp pairs. The energy dependences of these fluctuations from central 0–5% Au+Au collisions all demonstrate a smooth evolution with collision energy.« less

  12. Structure of graphene oxide dispersed with ZnO nanoparticles

    SciTech Connect (OSTI)

    Yadav, Rishikesh Pandey, Devendra K.; Khare, P. S.

    2014-10-15

    Graphene has been proposed as a promising two-dimensional nanomaterial with outstanding electronic, optical, thermal and mechanical properties for many applications. In present work a process of dispersion of graphene oxide with ZnO nanoparticles in ethanol solution with different pH values, have been studied. Samples have been characterized by XRD, SEM, PL, UV-visible spectroscopy and particles size measurement. The results analysis indicates overall improved emission spectrum. It has been observed that the average diameter of RGO (Reduced Graphene Oxide) decreases in presence of ZnO nanoparticles from 3.8?m to 0.41?m.

  13. Effect of ZnO seed layer on the morphology and optical properties of ZnO nanorods grown on GaN buffer layers

    SciTech Connect (OSTI)

    Nandi, R. Mohan, S. Major, S. S.; Srinivasa, R. S.

    2014-04-24

    ZnO nanorods were grown by chemical bath deposition on sputtered, polycrystalline GaN buffer layers with and without ZnO seed layer. Scanning electron microscopy and X-ray diffraction show that the ZnO nanorods on GaN buffer layers are not vertically well aligned. Photoluminescence spectrum of ZnO nanorods grown on GaN buffer layer, however exhibits a much stronger near-band-edge emission and negligible defect emission, compared to the nanorods grown on ZnO buffer layer. These features are attributed to gallium incorporation at the ZnO-GaN interface. The introduction of a thin (25 nm) ZnO seed layer on GaN buffer layer significantly improves the morphology and vertical alignment of ZnO-NRs without sacrificing the high optical quality of ZnO nanorods on GaN buffer layer. The presence of a thick (200 nm) ZnO seed layer completely masks the effect of the underlying GaN buffer layer on the morphology and optical properties of nanorods.

  14. Gd{sup 3+} incorporated ZnO nanoparticles: A versatile material

    SciTech Connect (OSTI)

    Kumar, Surender Sahare, P.D.

    2014-03-01

    Graphical abstract: - Highlights: • Chemically synthesized Gd{sup 3+} doped ZnO nanoparticles. • The broad visible emission of the ZnO is dependent on the surface defects and can be tailored by Gd{sup 3+} doing. • PL and magnetic properties are modified by Gd{sup 3+} doping. • Photocatalysis experiment reveals that the ZnO: Gd{sup 3+} degrades the Rh B dye faster than the undoped ZnO. - Abstract: Gd{sup 3+} doped ZnO nanoparticles are synthesized by wet chemical route method and investigated through structural, optical, magnetic and photocatalytic properties. Transmission Electron Microscopy technique has been performed on undoped and Gd{sup 3+} doped ZnO nanoparticles. X-ray diffraction, X-ray photoelectron spectroscopy and Raman analyses are carried out in order to examine the desired phase formation and substitution of Gd{sup 3+} in the ZnO matrix. Gd{sup 3+} doped ZnO nanoparticles show enhanced photoluminescent and ferromagnetic properties as compared to undoped ZnO. The broad visible emission of ZnO is found to be largely dependent on the surface defects and these surface defects can be tailored by Gd{sup 3+} doping concentration. Furthermore, Gd{sup 3+} doped ZnO nanoparticles also show improved photocatalytic properties as compared with undoped ZnO nanoparticles under ultraviolet irradiation.

  15. Efficient H{sub 2} production over Au/graphene/TiO{sub 2} induced by surface plasmon resonance of Au and band-gap excitation of TiO{sub 2}

    SciTech Connect (OSTI)

    Liu, Yang; Yu, Hongtao; Wang, Hua; Chen, Shuo; Quan, Xie

    2014-11-15

    Highlights: Both surface plasmon resonance and band-gap excitation were used for H{sub 2} production. Au/Gr/TiO{sub 2} composite photocatalyst was synthesized. Au/Gr/TiO{sub 2} exhibited enhancement of light absorption and charge separation. H{sub 2} production rate of Au/Gr/TiO{sub 2} was about 2 times as high as that of Au/TiO{sub 2}. - Abstract: H{sub 2} production over Au/Gr/TiO{sub 2} composite photocatalyst induced by surface plasmon resonance of Au and band-gap excitation of TiO{sub 2} using graphene (Gr) as an electron acceptor has been investigated. Electron paramagnetic resonance study indicated that, in this composite, Gr collected electrons not only from Au with surface plasmon resonance but also from TiO{sub 2} with band-gap excitation. Surface photovoltage and UVvis absorption measurements revealed that compared with Au/TiO{sub 2}, Au/Gr/TiO{sub 2} displayed more effective photogenerated charge separation and higher optical absorption. Benefiting from these advantages, the H{sub 2} production rate of Au/Gr/TiO{sub 2} composite with Gr content of 1.0 wt% and Au content of 2.0 wt% was about 2 times as high as that of Au/TiO{sub 2}. This work represents an important step toward the efficient application of both surface plasmon resonance and band-gap excitation on the way to converting solar light into chemical energy.

  16. Initial eccentricity in deformed {sup 197}Au+{sup 197}Au and {sup 238}U+{sup 238}U collisions at {radical}(s{sub NN})=200 GeV at the BNL Relativistic Heavy Ion Collider

    SciTech Connect (OSTI)

    Filip, Peter; Lednicky, Richard; Masui, Hiroshi; Xu Nu

    2009-11-15

    Initial eccentricity and eccentricity fluctuations of the interaction volume created in relativistic collisions of deformed {sup 197}Au and {sup 238}U nuclei are studied using optical and Monte Carlo (MC) Glauber simulations. It is found that the nonsphericity noticeably influences the average eccentricity in central collisions, and eccentricity fluctuations are enhanced from deformation. Quantitative results are obtained for Au+Au and U+U collisions at energy {radical}(s{sub NN})=200 GeV.

  17. Whitfield Solar Ltd | Open Energy Information

    Open Energy Info (EERE)

    Kingdom Zip: RG6 6AU Sector: Renewable Energy, Solar Product: Developing solar photovoltaic concentrators aimed at generating clean renewable energy for the world market....

  18. Photoinduced reduction of surface states in Fe:ZnO

    SciTech Connect (OSTI)

    Knut, R. Palmgren, P.; Karis, O.; Lagerqvist, U.; Pohl, A.; Pal, P.; Svedlindh, P.

    2015-05-28

    We report on the electronic structure of nano-crystalline Fe:ZnO, which has recently been found to be an efficient photocatalyst. Using resonant photoemission spectroscopy, we determine the binding energy of Fe 3d states corresponding to different valencies and coordination of the Fe atoms. The photo-activity of ZnO reduces Fe from 3+ to 2+ in the surface region of the nano-crystalline material due to the formation of oxygen vacancies. Electronic states corresponding to low-spin Fe{sup 2+} are observed and attributed to crystal field modification at the surface. These states are potentially important for the photocatalytic sensitivity to visible light due to their location deep in the ZnO bandgap. X-ray absorption and x-ray photoemission spectroscopy suggest that Fe is only homogeneously distributed for concentrations up to 3%. Increased concentrations does not result in a higher concentration of Fe ions in the surface region. This is limiting the photocatalytic functionality of ZnO, where the most efficient Fe doping concentration has been shown to be 1%-4%.

  19. Self-focused ZnO transducers for ultrasonic biomicroscopy

    SciTech Connect (OSTI)

    Cannata, J. M.; Williams, J. A.; Zhou, Q. F.; Sun, L.; Shung, K. K.; Yu, H.; Kim, E. S.

    2008-04-15

    A simple fabrication technique was developed to produce high frequency (100 MHz) self-focused single element transducers with sputtered zinc oxide (ZnO) crystal films. This technique requires the sputtering of a ZnO film directly onto a curved backing substrate. Transducers were fabricated by sputtering an 18 {mu}m thick ZnO layer on 2 mm diameter aluminum rods with ends shaped and polished to produce a 2 mm focus or f-number equal to one. The aluminum rod served a dual purpose as the backing layer and positive electrode for the resultant transducers. A 4 {mu}m Parylene matching layer was deposited on the transducers after housing and interconnect. This matching layer was used to protect the substrate and condition the transfer of acoustic energy between the ZnO film and the load medium. The pulse-echo response for a representative transducer was centered at 101 MHz with a -6 dB bandwidth of 49%. The measured two way insertion loss was 44 dB. A tungsten wire phantom and an adult zebrafish eye were imaged to show the capability of these transducers.

  20. TUNING OF SIZE AND SHAPE OF AU-PT NANOCATALYST FOR DIRECT METHANOL FUEL CELLS

    SciTech Connect (OSTI)

    Murph, S.

    2011-04-20

    In this paper, we report the precise control of the size, shape and surface morphology of Au-Pt nanocatalysts (cubes, blocks, octahedrons and dogbones) synthesized via a seed-mediated approach. Gold 'seeds' of different aspect ratios (1 to 4.2), grown by a silver-assisted approach, were used as templates for high-yield production of novel Au-Pt nanocatalysts at a low temperature (40 C). Characterization by electron microscopy (SEM, TEM, HRTEM), energy dispersive X-ray analysis (EDX), UV-Vis spectroscopy, zeta-potential (surface charge), atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS) and inductively coupled plasma mass spectrometry (ICP-MS) were used to better understand their physico-chemical properties, preferred reactivities and underlying nanoparticle growth mechanism. A rotating disk electrode was used to evaluate the Au-Pt nanocatalysts electrochemical performance in the oxygen reduction reaction (ORR) and the methanol oxidation reaction (MOR) of direct methanol fuel cells. The results indicate the Au-Pt dogbones are partially and in some cases completely unaffected by methanol poisoning during the evaluation of the ORR. The ORR performance of the octahedron particles in the absence of MeOH is superior to that of the Au-Pt dogbones and Pt-black, however its performance is affected by the presence of MeOH.

  1. INTERSTELLAR PICK-UP IONS OBSERVED BETWEEN 11 AND 22 AU BY NEW HORIZONS

    SciTech Connect (OSTI)

    Randol, B. M.; McComas, D. J.; Schwadron, N. A.

    2013-05-10

    We report new observations by the Solar Wind Around Pluto instrument on the New Horizons spacecraft, which measures energy per charge (E/q) spectra of solar wind and interstellar pick-up ions (PUIs) between 11 AU and 22 AU from the Sun. The data provide an unprecedented look at PUIs as there have been very few measurements of PUIs beyond 10 AU. We analyzed the PUI part of the spectra by comparing them to the classic Vasyliunas and Siscoe PUI model. Our analysis indicates that PUIs are usually well-described by this distribution. We derive parameters relevant to PUI studies, such as the ionization rate normalized to 1 AU. Our result for the average ionization rate between 11 and 12 AU agrees with an independently derived average value found during the same time. Later, we find a general increase in the ionization rate, which is consistent with the increase in solar activity. We also calculate the PUI thermal pressure, which appears to be roughly consistent with previous results. Through fitting of the solar wind proton peaks in our spectra, we derive solar wind thermal pressures. Based on our analysis, we predict a ratio of PUI thermal pressure to solar wind thermal pressure just inside the termination shock to be between 100 and >1000.

  2. Spin correlations and electron transport in MnBi:Au films

    SciTech Connect (OSTI)

    Kharel, P.; Skomski, R.; Sellmyer, D. J.

    2011-04-01

    The structural, magnetic, and electron transport properties of Mn{sub 55-x}Au{sub x}Bi{sub 45} (x = 0, 4.5) thin films prepared by magnetron sputtering have been investigated. The magnetization of the MnBi films decreases and the coercivity increases due to Au doping. The temperature dependence of resistivity between 2 to 300 K shows that the films are metallic but the 4.5% Au-doped film shows a Kondo behavior with resistance minimum at 10.2 K. The magnetoresistance is anisotropic and the positive transverse magnetoresistance is significantly enhanced (16.3% at 70 kOe) by Au doping. We interpret these data in terms of a model in which Au atoms preferentially substitute for Mn atoms on the Mn lattice, and some Mn atoms are displaced to interstitial sites in the NiAs structure. These interstitial Mn atoms are coupled antiferromagnetically to the Mn atoms on the original Mn lattice leading to the large decrease in magnetization, Kondo effect, and the positive magnetoresistance.

  3. Super-Stable, Highly Monodisperse Plasmonic Nanocrystals with 500 Gold Atoms: Au~500(SR)~120

    SciTech Connect (OSTI)

    Kumara, Chanaka; Zuo, Xiaobing; Ilavsky, Dr. Jan; Chapman, Karena; Cullen, David A; Dass, Amala

    2014-01-01

    Determining the composition of plasmonic nanoparticles is challenging due to a deficiency in tools capable of accurately evaluating the number of atoms. Mass spectrometry plays a significant role in determining nanoparticle composition at the atomic level. Significant progress has been made in understanding ultra-small gold nanoparticles, like Au25(SR)18 and Au38(SR)24, with a Au core diameter of 0.97 and 1.3 nm, respectively. However, progress in small plasmonic nanoparticles (2 - 5 nm) is currently challenging, due in part to limitations in synthesizing monodisperse nanoparticles. Here, we report a plasmonic nanocrystal that is highly monodisperse, with an unprecedented variation of less than 20 gold atoms. The composition of the super-stable plasmonic nanocrystals at 115 kDa was determined to contain Au500 10SR120 3. The Au~500 system, named Faraduarate-500, is the largest size to be characterized using high resolution ESI mass spectrometry. Atomic pair distribution function (PDF) data shows that the local atomic structure is consistent with a face-centered cubic (fcc) or Marks decahedral arrangement. High resolution scanning transmission electron microscopy images show that the diameter is 2.4 0.1 nm. The radius of gyration measured by small angle X-ray scattering (SAXS), is 1.05 0.05 nm, and the size and the shape of SAXS molecular envelope are in agreement with TEM and PDF measurements.

  4. Controlled growth and multi-photon luminescence of hexagonal arrays of Au nanoparticles on anodic aluminum oxide templates

    SciTech Connect (OSTI)

    Li Jianbo; Yu Ying; Peng Xiaoniu; Yang Zhongjian; Zhou Li; Zhou Zhangkai

    2012-06-15

    Au nanoparticles were deposited onto anodic aluminum oxide (AAO) templates by using a rotating sputtering technique. Interestingly, hexagonal arrays of Au nanoparticles were obtained at an appropriate rotating rate and deposition time. Strong three-photon luminescence was observed from the hexagonally arrayed Au nanoparticles, which is attributed to the strong enhancements of local electromagnetic fields at both excitation and emission wavelengths. Our findings provide a new method to prepare Au nanoparticle arrays with large field enhancements and could have prospective applications in plasmonic nanodevices, such as surface-enhanced Raman scattering substrates, and biosensors.

  5. J rg Calefice | Open Energy Information

    Open Energy Info (EERE)

    it. Jrg Calefice is a company located in Germany . References " Jrg Calefice" Retrieved from "http:en.openei.orgwindex.php?titleJrgCalefice&oldid782975...

  6. RG&E (Gas)- Residential Efficiency Program

    Broader source: Energy.gov [DOE]

    An online rebate reservation system is used to ensure program funds are not overextended. All new rebate requests must first be reserved in the rebate reservation system to be valid. The program...

  7. Defect Chemistry Study of Nitrogen Doped ZnO Thin Films

    SciTech Connect (OSTI)

    Miami University: Dr. Lei L. Kerr Wright State University: Dr. David C. Look and Dr. Zhaoqiang Fang

    2009-11-29

    Our team has investigated the defect chemistry of ZnO:N and developed a thermal evaporation (vapor-phase) method to synthesis p-type ZnO:N. Enhanced p-type conductivity of nitrogen doped ZnO via nano/micro structured rods and Zn-rich Co-doping process were studied. Also, an extended X-Ray absorption fine structure study of p-type nitrogen doped ZnO was conducted. Also reported are Hall-effect, photoluminescence, and DLTS studies.

  8. Resorption Rate Tunable Bioceramic: Si, Zn-Modified Tricalcium Phosphate

    SciTech Connect (OSTI)

    Xiang Wei

    2006-08-09

    This dissertation is organized in an alternate format. Several manuscripts which have already been published or are to be submitted for publication have been included as separate chapters. Chapter 1 is a general introduction which describes the dissertation organization and introduces the human bone and ceramic materials as bone substitute. Chapter 2 is the background and literature review on dissolution behavior of calcium phosphate, and discussion of motivation for this research. Chapter 3 is a manuscript entitled ''Si,Zn-modified tricalcium phosphate: a phase composition and crystal structure study'', which was published in ''Key Engineering Materials'' [1]. Chapter 4 gives more crystal structure details by neutron powder diffraction, which identifies the position for Si and Zn substitution and explains the stabilization mechanism of the structure. A manuscript entitled ''Crystal structure analysis of Si, Zn-modified Tricalcium phosphate by Neutron Powder Diffraction'' will be submitted to Biomaterials [2]. Chapter 5 is a manuscript, entitled ''Dissolution behavior and cytotoxicity test of Si, Zn-modified tricalcium phosphate'', which is to be submitted to Biomaterials [3]. This paper discusses the additives effect on the dissolution behavior of TCP, and cytotoxicity test result is also included. Chapter 6 is the study of hydrolysis process of {alpha}-tricalcium phosphate in the simulated body fluid, and the phase development during drying process is discussed. A manuscript entitled ''Hydrolysis of {alpha}-tricalcium phosphate in simulated body fluid and phase transformation during drying process'' is to be submitted to Biomaterials [4]. Ozan Ugurlu is included as co-authors in these two papers due to his TEM contributions. Appendix A is the general introduction of the materials synthesis, crystal structure and preliminary dissolution result. A manuscript entitled ''Resorption rate tunable bioceramic: Si and Zn-modified tricalcium phosphate'' was published in

  9. Zn-Site Determination in Protein Encapsulated ZnxFe3-xO4 Nanoparticles

    SciTech Connect (OSTI)

    Pool, V. L.; Klem, M. T.; Holroyd, J.; Harris, T.; Arenholz, E.; Young, M.; Douglas, T.; Idzerda, Y. U.

    2008-10-01

    The X-ray absorption spectra of the Fe and Zn L-edges for 6.7 nm Fe{sub 3}O{sub 4} nanoparticles grown inside 12 nm ferritin protein cages with 10%, 15%, 20% and 33% zinc doping, shows that the Zn is substitutional as Zn{sup 2+} within the iron oxide host structure. A Neel-Arrhenius plot of the blocking temperature in the frequency dependent ac-susceptibility measurements show that the particles are non-interacting and that the anisotropy energy barrier is reduced with Zn loading. X-ray magnetic circular dichroism (XMCD) of the Fe displays a linear decrease with Zn-doping in sharp contrast to the initial increase present in the bulk system. The most plausible explanation for the moment decrease is that Zn substitutes preferentially into the tetrahedral A-site as a Zn{sup 2+} cation, generating a mixed spinel.

  10. Theoretical study of syngas hydrogenation to methanol on the polar Zn-terminated ZnO(0001) surface

    SciTech Connect (OSTI)

    Zhao, Ya-Fan; Rousseau, Roger J.; Li, Jun; Mei, Donghai

    2012-08-02

    Methanol synthesis from syngas (CO/CO2/H2) hydrogenation on the perfect Znterminated polar ZnO(0001) surface have been investigated using periodic density functional theory calculations. Our results show that direct CO2 hydrogenation to methanol on the perfect ZnO(0001) surface is unlikely because in the presence of surface atomic H and O the highly stable formate (HCOO) and carbonate (CO3) readily produced from CO2 with low barriers 0.11 and 0.09 eV will eventually accumulate and block the active sites of the ZnO(0001) surface. In contrast, methanol synthesis from CO hydrogenation is thermodynamically and kinetically feasible on the perfect ZnO(0001) surface. CO can be consecutively hydrogenated into formyl (HCO), formaldehyde (H2CO), methoxy (H3CO) intermediates, leading to the final formation of methanol (H3COH). The reaction route via hydroxymethyl (H2COH) intermediate, a previously proposed species on the defected Oterminated ZnO( ) surface, is kinetically inhibited on the perfect ZnO(0001) surface. The rate-determining step in the consecutive CO hydrogenation route is the hydrogenation of H3CO to H3COH. We also note that this last hydrogenation step is pronouncedly facilitated in the presence of water by lowering the activation barrier from 1.02 to 0.55 eV. This work was supported by the U.S. Department of Energy Office of Basic Energy Sciences, Division of Chemical Sciences, Biosciences and Geosciences, and performed at EMSL, a national scientific user facility sponsored by the Department of Energys Office of Biological and Environmental Research located at Pacific Northwest National Laboratory (PNNL). Computational resources were provided at EMSL and the National Energy Research Scientific Computing Center at Lawrence Berkeley National Laboratory. J. Li and Y.-F. Zhao were also financially supported by the National Natural Science Foundation of China (Nos. 20933003 and 91026003) and the National Basic Research Program of China (No. 2011CB932400). Y

  11. Enhanced transient reactivity of an O-sputtered Au(111) surface

    SciTech Connect (OSTI)

    Biener, M M; Biener, J; Friend, C M

    2004-12-02

    The interaction of SO{sub 2} with oxygen-sputtered Au(111) surfaces ({theta}{sub oxygen} {le} 0.35 ML) was studied by monitoring the oxygen and sulfur coverages as a function of SO{sub 2} exposure. Two reaction regimes were observed: oxygen depletion followed by sulfur deposition. An enhanced, transient sulfur deposition rate is observed at the oxygen depletion point. This effect is specifically pronounced if the Au surface is continuously exposed to SO{sub 2}. The enhanced reactivity towards S deposition seems to be linked to the presence of highly reactive, under-coordinated Au atoms. Adsorbed oxygen appears to stabilize, but also to block these sites. In absence of the stabilization effect of adsorbed oxygen, i.e. at the oxygen depletion point, the enhanced reactivity decays on a timescale of a few minutes. These observations shed a new light on the catalytic reactivity of highly dispersed gold nanoparticles.

  12. Systematic study of charged-pion and kaon femtoscopy in Au+Au collisions at √sNN = 200 GeV

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Adare, A.

    2015-09-23

    We present a systematic study of charged pion and kaon interferometry in Au+Au collisions at √sNN=200 GeV. The kaon mean source radii are found to be larger than pion radii in the outward and longitudinal directions for the same transverse mass; this difference increases for more central collisions. The azimuthal-angle dependence of the radii was measured with respect to the second-order event plane and similar oscillations of the source radii were found for pions and kaons. Hydrodynamic models qualitatively describe the similar oscillations of the mean source radii for pions and kaons, but they do not fully describe the transverse-massmore »dependence of the oscillations.« less

  13. Systematic study of charged-pion and kaon femtoscopy in Au+Au collisions at √sNN = 200 GeV

    SciTech Connect (OSTI)

    Adare, A.

    2015-09-23

    We present a systematic study of charged pion and kaon interferometry in Au+Au collisions at √sNN=200 GeV. The kaon mean source radii are found to be larger than pion radii in the outward and longitudinal directions for the same transverse mass; this difference increases for more central collisions. The azimuthal-angle dependence of the radii was measured with respect to the second-order event plane and similar oscillations of the source radii were found for pions and kaons. Hydrodynamic models qualitatively describe the similar oscillations of the mean source radii for pions and kaons, but they do not fully describe the transverse-mass dependence of the oscillations.

  14. Hadronization geometry and charge-dependent two-particlecorrelation on momentum subspace (eta, phi) in Au-Au collisions atsqrt(sNN) = 130 GeV

    SciTech Connect (OSTI)

    Adams, J.; Aggarwal, M.M.; Ahammed, Z.; Amonett, J.; Anderson,B.D.; Arkhipkin, D.; Averichev, G.S.; Badyal, S.K.; Bai, Y.; Balewski,J.; Barannikova, O.; Barnby, L.S.; Baudot, J.; Bekele, S.; Belaga, V.V.; Bellwied, R.; Berger, J.; Bezverkhny, B.I.; Bharadwaj, S.; Bhasin, A.; Bhati, A.K.; Bhatia, V.S.; Bichsel, H.; Billmeier, A.; Bland, L.C.; Blyth, C.O.; Bonner, B.E.; Botje, M.; Boucham, A.; Brandin, A.V.; Bravar,A.; Bystersky, M.; Cadman, R.V.; Cai, X.Z.; Caines, H.; Calderon de laBarca Sanchez, M.; Carroll, J.; Castillo, J.; Cebra, D.; Chajecki, Z.; Chaloupka, P.; Chattopdhyay, S.; Chen, H.F.; Chen, Y.; Cheng, J.; Cherney, M.; Chikanian, A.; Christie, W.; Coffin, J.P.; Cormier, T.M.; Cramer, J.G.; Crawford, H.J.; Das, D.; Das, S.; De Moura, M.M.; Derevschikov, A.A.; Didenko, L.; Dietel, T.; Dogra, S.M.; Dong, W.J.; Dong, X.; Draper, J.E.; Du, F.; Dubey, A.K.; Dunin, V.B.; Dunlop, J.C.; Dutta Mazumdar, M.R.; Eckardt, V.; Edwards, W.R.; Efimov, L.G.; Emelianov, V.; Engelage, J.; Eppley, G.; Erazmus, B.; Estienne, M.; Fachini, P.; Faivre, J.; Fatemi, R.; Fedorisin, J.; Filimonov, K.; Filip,P.; Finch, E.; Fine, V.; Fisyak, Y.; Foley, K.J.; Fomenko, K.; Fu, J.; Gagliardi, C.A.; Gans, J.; Ganti, M.S.; Gaudichet, L.; Geurts, F.; Ghazikhanian, V.; Ghosh, P.; Gonzalez, J.E.; Grachov, O.; Grebenyuk, O.; Grosnick, D.; Guertin, S.M.; Guo, Y.; Gupta, A.; Guiterrez, T.D.; Hallman, T.J.; Hamed, A.; Hardtke, D.; Harris, J.W.; Heinz, M.; Henry,T.W.; Heppelmann, S.; Hippolyte, B.; Hirsch, A.; Hjort, E.; Hoffmann,G.W.; Huang, H.Z.; Huang, S.L.; Hughes, E.W.; Humanic, T.J.; Igo, G.; Ishihara, A.; Jacobs, P.; Jacobs, W.W.; Janik, M.; Jiang, H.; Jones,P.G.; Judd, E.G.; Kabana, S.; Kang, K.; Kaplan, M.; Keane, D.; Khodyrv,V.Yu.; Kiryluk, J.; Kisiel, A.; Kislov, E.M.; Klay, J.; Klein, S.R.; Klyachko, A.; Koetke, D.D.; Kollegger, T.; Kopytine, S.M.; Kotchenda, L.; Kramer, M.; Kravtsov, P.; Kravtsov, V.I.; Krueger, K.; Kuhn, C.; Kulikov,A.I.; et al.

    2004-09-23

    We present the first measurements of charge-dependent two-particle correlations on momentum-space difference variables {eta}{sub 1}-{eta}{sub 2} (pseudorapidity) and {phi}{sub 1}-{phi}{sub 2} (azimuth) for primary charged hadrons with transverse momentum 0.15 {le} p{sub t} {le} 2 GeV/c and |{eta}| {le} 1.3 from Au-Au collisions at {radical}s{sub NN} = 130 GeV. We observe correlation structures not predicted by theory but consistent with evolution of hadron emission geometry with increasing centrality from one-dimensional fragmentation of color strings to higher-dimensional fragmentation of a hadron-opaque bulk medium.

  15. Event-by-event hexb pt hexb fluctuations in Au-Au collisions atsqrt(sNN) = 130 GeV

    SciTech Connect (OSTI)

    Adams, J.; Adler, C.; Aggarwal, M.M.; Ahammed, Z.; Amonett, J.; Anderson, B.D.; Anderson, M; Arkhipkin, D.; Averichev, G.S.; Badyal,S.K.; Balewski, J.; Barannikova, O.; Barnby, L.S.; Baudot, J.; Bekele,S.; Belaga, V.V.; Bellwied, R.; Berger, J.; Bezverkhny, B.I.; Bhardwaj,S.; Bhaskar, P.; Bhati, A.K.; Bichsel, H.; Billmeier, A.; Bland, L.C.; Blyth, C.O.; Bonner, B.E.; Botje, M.; Boucham, A.; Brandin, A.; Bravar,A.; Cadman, R.V.; Cai, X.Z.; Caines, H.; Calderon de la Barca Sanchez,M.; Carroll, J.; Castillo, J.; Castro, M.; Cebra, D.; Chaloupka, P.; Chattopadhyay, S.; Chen, H.F.; Chen, Y.; Chernenko, S.P.; Cherney, M.; Chikanian, A.; Choi, B.; Christie, W.; Coffin, J.P.; Cormier, T.M.; Cramer, J.G.; Crawford, H.J.; Das, D.; Das, S.; Derevschikov, A.A.; Didenko, L.; Dietel, T.; Dong, X.; Draper, J.E.; Du, F.; Dubey, A.K.; Dunin, V.B.; Dunlop, J.C.; Dutta Majumdar, M.R.; Eckardt, V.; Efimov,L.G.; Emelianov, V.; Engelage, J.; Eppley, G.; Erazmus, B.; Estienne, M.; Fachini, P.; Faine, V.; Faivre, J.; Fatemi, R.; Filimonov, K.; Filip, P.; Finch, E.; Fisyak, Y.; Flierl, D.; Foley, K.J.; Fu, J.; Gagliardi, C.A.; Ganti, M.S.; Gutierrez, T.D.; Gagunashvili, N.; Gans, J.; Gaudichet, L.; Germain, M.; Geurts, F.; Ghazikhanian, V.; Ghosh, P.; Gonzalez, J.E.; Grachov, O.; Grigoriev, V.; Cronstal, S.; Grosnick, D.; Guedon, M.; Guertin, S.M.; Gupta, A.; Gushin, E.; Hallman, T.J.; Hardtke, D.; Harris,J.W.; Heinz, M.; Henry, T.W.; Heppelmann, S.; Herston, T.; Hippolyte, B.; Hirsch, A.; Hjort, E.; Hoffmann, G.W.; Horsley, M.; Huang, H.Z.; Huang,S.L.; Humanic, T.J.; Igo, G.; Ishihara, A.; Jacobs, P.; Jacobs, W.W.; Janik, M.; Johnson, I.; Jones, P.G.; Judd, E.G.; Kabana, S.; Kaneta, M.; Kaplan, M.; Keane, D.; Kiryluk, J.; Kisiel, A.; Klay, J.; Klein, S.R.; Klyachko, A.; Koetke, D.D.; Kollegger, T.; Konstantinov, A.S.; Kopytine,S.M.; Kotchenda, L.; Kovalenko, A.D.; Kramer, M.; Kravtsov, P.; Krueger,K.; Kuhn, C.; Kulikov, A.I.; Kumar, A.; et al.

    2003-09-02

    We present the first large-acceptance measurement of event-wise fluctuations in Au-Au collisions at {radical}s{sub NN} = 130 GeV. Significant nonstatistical fluctuations are observed. The measured fractional r.m.s. width excess of the event-wise distribution for the 15% most-central events for charged hadrons within |{eta}| < 1 and 0.15 {le} p{sub t} {le} 2 GeV/c is 13.7 {+-} 0.1(stat) {+-}1.3(syst)% relative to a statistical reference. The variation of charge-independent fluctuation excess with centrality is non-monotonic but smooth. Charge-dependent nonstatistical fluctuations are also observed.

  16. Particle-type dependence of azimuthal anisotropy and nuclearmodification of particle production in Au+Au collisions at sNN = 200GeV

    SciTech Connect (OSTI)

    Adams, J.; Adler, C.; Aggarwal, M.M.; Ahammed, Z.; Amonett, J.; Anderson, B.D.; Anderson, M.; Arkhipkin, D.; Averichev, G.S.; Badyal,S.K.; Balewski, J.; Barannikova, O.; Barnby, L.S.; Baudot, J.; Bekele,S.; Belaga, V.V.; Bellwied, R.; Berger, J.; Bezverkhny, B.I.; Bhardwaj,S.; Bhaskar, P.; Bhati, A.K.; Billmeier, A.; Bland, L.C.; Blyth, C.O.; Bonner, B.E.; Botje, M.; Boucham, A.; Brandin, A.; Bravar, A.; Cadman,R.V.; Cai, X.Z.; Caines, H.; Calderon de la Barca Sanchez, M.; Carroll,J.; Castillo, J.; Castro, M.; Cebra, D.; Chaloupka, P.; Chattopadhyay,S.; Chen, H.F.; Chen, Y.; Chernenko, S.P.; Cherney, M.; Chikanian, A.; Choi, B.; Christie, W.; Coffin, J.P.; Cormier, T.M.; Cramer, J.G.; Crawford, H.J.; Das, D.; Das, S.; Derevschikov, A.A.; Didenko, L.; Dietel, T.; Dong, W.J.; Dong, X.; Draper, J.E.; Du, F.; Dubey, A.K.; Dunin, V.B.; Dunlop, J.C.; Dutta Majumdar, M.R.; Eckardt, V.; Efimov,L.G.; Emelianov, V.; Engelage, J.; Eppley, G.; Erazmus, B.; Fachini, P.; Faine, V.; Faivre, J.; Fatemi, R.; Filimonov, K.; Filip, P.; Finch, E.; Fisyak, Y.; Flierl, D.; Foley, K.J.; Fu, J.; Gagliardi, C.A.; Gagunashvili, N.; Gans, J.; Ganti, M.S.; Gutierrez, T.D.; Gaudichet, L.; Germain, M.; Geurts, F.; Ghazikhanian, V.; Ghosh, P.; Gonzalez, J.E.; Grachov, O.; Grigoriev, V.; Gronstal, S.; Drosnick, D.; Guedon, M.; Guertin, S.M.; Gushin, E.; Hallman, T.J.; Hardtke, D.; Harris, J.W.; Heinz, M.; Henry, T.W.; Heppelmann, S.; Herston, T.; Hippolyte, B.; Hirsch, A.; Hjort, E.; Hoffmann, G.W.; Horsley, M.; Huang, H.Z.; Huang,S.L.; Humanic, T.J.; Igo, G.; Ishihara, A.; Jacobs, P.; Jacobs, W.W.; Janik, M.; Johnson, I.; Jones, P.G.; Judd, E.G.; Kabana, S.; Kaneta, M.; Kaplan, M.; Keane, D.; Kiryluk, J.; Kisiel, A.; Klay, J.; Klein, S.R.; Klyachko, A.; Koetke, D.D.; Kollegger, T.; Konstantinov, A.; Kopytine,S.M.; Kotchenda, L.; Kovalenko, A.D.; Kramer, M.; Kravtsov, P.; Krueger,K.; Kuhn, C.; Kulikov, A.I.; Kunde, G.J.; Kunz, C.L.; Kutuev, R.K.; et al.

    2003-06-18

    We present STAR measurements of the azimuthal anisotropy parameter v{sub 2} and the binary-collision scaled centrality ratio R{sub CP} for kaons and lambdas ({Lambda} + {bar {Lambda}}) at mid-rapidity in Au+Au collisions at {radical}s{sub NN} = 200 GeV. In combination, the v{sub 2} and R{sub CP} particle-type dependencies contradict expectations from partonic energy loss followed by standard fragmentation in vacuum. We establish p{sub T} {approx} 5 GeV/c as the value where the centrality dependent baryon enhancement ends. The K{sub S}{sup 0} and {Lambda} + {bar {Lambda}} v{sub 2} values are consistent with expectations of constituent-quark-number scaling from models of hadron formation by parton coalescence or recombination.

  17. Rapidity and centrality dependence of proton and anti-proton production from 197Au+197Au collisions at {radical}(s{sub NN}) = 130 GeV

    SciTech Connect (OSTI)

    Adams, J.; Adler, C.; Aggarwal, M.M.; Ahammed, Z.; Amonett, J.; Anderson, B.D.; Anderson, M.; Arkhipkin, D.; Averichev, G.S.; Badyal, S.K.; Balewski, J.; Barannikova, O.; Barnby, L.S.; Baudot, J.; Bekele, S.; Belaga, V.V.; Bellwied, R.; Berger, J.; Bezverkhny, B.I.; Bhardwaj, S.; Bhaskar, P.; Bhati, A.K.; Bichsel, H.; Billmeier, A.; Bland, L.C.; Blyth, C.O.; Bonner, B.E.; Botje, M.; Boucham, A.; Brandin, A.; Bravar, A.; Cadman, R.V.; Cai, X.Z.; Caines, H.; Calderon de la Barca Sanchez, M.; Cardenas, A.; Carroll, J.; Castillo, J.; Castro, M.; Cebra, D.; Chaloupka, P.; Chattopadhyay, S.; Chen, H.F.; Chen, Y.; Chernenko, S.P.; Cherney, M.; Chikanian, A.; Choi, B.; Christie, W.; Coffin, J.P.; Cormier, T.M.; Corral, M.M.; Cramer, J.G.; Crawford, H.J.; Das, D.; Das, S.; Derevschikov, A.A.; Didenko, L.; Dietel, T.; Dong, X.; Draper, J.E.; Du, F.; Dubey, A.K.; Dunin, V.B.; Dunlop, J.C.; Dutta Mazumdar, M.R.; Eckardt, V.; Efimov, L.G.; Emelianov, V.; Engelage, J.; Eppley, G.; Erazmus, B.; Fachini, P.; Faine, V.; Faivre, J.; Fatemi, R.; Filimonov, K.; Filip, P.; Finch, E.; Fisyak, Y.; Flierl, D.; Foley, K.J.; Fu, J.; Gagliardi, C.A.; Ganti, M.S.; Gutierrez, T.D.; Gagunashvili, N.; Gans, J.; Gaudichet, L.; Germain, M.; Geurts, F.; Ghazikhanian, V.; Ghosh, P.; Gonzalez, J.E.; Grachov, O.; Grigoriev, V.; Grosnick, D.; Guedon, M.; Guertin, S.M.; Gupta, A.; Gushin, E.; Hallman, T.J.; Hardtke, D.; Harris, J.W.; Heinz, M.; Henry, T.W.; Heppelmann, S.; Herston, T.; Hippolyte, B.; Hirsch, A.; Hjort, E.; Hoffmann, G.W.; Horsley, M.; Huang, H.Z.; Huang, S.L.; Humanic, T.J.; Igo, G.; Ishihara, A.; Jacobs, P.; Jacobs, W.W.; Janik, M.; Johnson, I.; Jones, P.G.; Judd, E.G.; Kabana, S.; Kaneta, M.; Kaplan, M.; Keane, D.; Kiryluk, J.; Kisiel, A.; Klay, J.; Klein, S.R.; Klyachko, A.; Koetke, D.D.; Kollegger, T.; Konstantinov, A.S.; Kopytine, M.; Kotchenda, L.; Kovalenko, A.D.; Kramer, M.; Kravtsov, P.; Krueger, K.; Kuhn, C.; Kulikov, A.I.; Kumar, A.; et al.

    2003-06-20

    We report on the rapidity and centrality dependence of proton and anti-proton transverse mass distributions from {sup 197}Au + {sup 197}Au collisions at {radical}s{sub NN} = 130 GeV as measured by the STAR experiment at RHIC. Our results are from the rapidity and transverse momentum range of |y| < 0.5 and 0.35 < p{sub t} < 1.00 GeV/c. For both protons and anti-protons, transverse mass distributions become more convex from peripheral to central collisions demonstrating characteristics of collective expansion. The measured rapidity distributions and the mean transverse momenta versus rapidity are flat within |y| < 0.5. Comparisons of our data with results from model calculations indicate that in order to obtain a consistent picture of the proton(anti-proton) yields and transverse mass distributions the possibility of pre-hadronic collective expansion may have to be taken into account.

  18. Systematic study of charged-pion and kaon femtoscopy in Au+Au collisions at √sNN = 200 GeV

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Adare, A.

    2015-09-23

    We present a systematic study of charged pion and kaon interferometry in Au+Au collisions at √sNN=200 GeV. The kaon mean source radii are found to be larger than pion radii in the outward and longitudinal directions for the same transverse mass; this difference increases for more central collisions. The azimuthal-angle dependence of the radii was measured with respect to the second-order event plane and similar oscillations of the source radii were found for pions and kaons. Hydrodynamic models qualitatively describe the similar oscillations of the mean source radii for pions and kaons, but they do not fully describe the transverse-massmore » dependence of the oscillations.« less

  19. Heavy-quark production and elliptic flow in Au+Au collisions at ?sNN=62.4 GeV

    SciTech Connect (OSTI)

    Adare, A.

    2015-04-28

    In this study, we present measurements of electrons and positrons from the semileptonic decays of heavy-flavor hadrons at midrapidity (|y|< 0.35) in Au+Au collisions at ?sNN = 62.4 GeV. The data were collected in 2010 by the PHENIX experiment that included the new hadron-blind detector. The invariant yield of electrons from heavy-flavor decays is measured as a function of transverse momentum in the range 1 < peT < 5 GeV/c. The invariant yield per binary collision is slightly enhanced above the p+p reference in Au+Au 0%20%, 20%40%, and 40%60% centralities at a comparable level. At this low beam energy this may be a result of the interplay between initial-state Cronin effects, final-state flow, and energy loss in medium. The v? of electrons from heavy-flavor decays is nonzero when averaged between 1.3 < peT < 2.5 GeV/c for 0%40% centrality collisions at ?sNN = 62.4 GeV. For 20%40% centrality collisions, the v? at ?sNN = 62.4 GeV is smaller than that for heavy-flavor decays at ?sNN = 200 GeV. The v? of the electrons from heavy-flavor decay at the lower beam energy is also smaller than v? for pions. Both results indicate that the heavy-quarks interact with the medium formed in these collisions, but they may not be at the same level of thermalization with the medium as observed at ?sNN = 200 GeV.

  20. Heavy-quark production and elliptic flow in Au+Au collisions at √sNN=62.4 GeV

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Adare, A.

    2015-04-28

    In this study, we present measurements of electrons and positrons from the semileptonic decays of heavy-flavor hadrons at midrapidity (|y|< 0.35) in Au+Au collisions at √sNN = 62.4 GeV. The data were collected in 2010 by the PHENIX experiment that included the new hadron-blind detector. The invariant yield of electrons from heavy-flavor decays is measured as a function of transverse momentum in the range 1 < peT < 5 GeV/c. The invariant yield per binary collision is slightly enhanced above the p+p reference in Au+Au 0%–20%, 20%–40%, and 40%–60% centralities at a comparable level. At this low beam energy thismore » may be a result of the interplay between initial-state Cronin effects, final-state flow, and energy loss in medium. The v₂ of electrons from heavy-flavor decays is nonzero when averaged between 1.3 < peT < 2.5 GeV/c for 0%–40% centrality collisions at √sNN = 62.4 GeV. For 20%–40% centrality collisions, the v₂ at √sNN = 62.4 GeV is smaller than that for heavy-flavor decays at √sNN = 200 GeV. The v₂ of the electrons from heavy-flavor decay at the lower beam energy is also smaller than v₂ for pions. Both results indicate that the heavy-quarks interact with the medium formed in these collisions, but they may not be at the same level of thermalization with the medium as observed at √sNN = 200 GeV.« less

  1. High-frequency signal transmission through single-atom contacts of Au and Pt

    SciTech Connect (OSTI)

    Aoyama, Shodai; Kurokawa, Shu; Sakai, Akira

    2015-03-23

    Signal transmission through atom-sized contacts of Au and Pt has been studied at room temperature for frequencies from 9 kHz to 1 GHz and for conductances (1?10)G{sub 0} (G?2e{sup 2}/h is the quantum unit of conductance). We measured the frequency spectrum of S parameter S{sub 21}=|S{sub 21}|e{sup i?} and found ??0 up to 1?GHz for all contacts irrespective of their conductance. Our observations directly prove that the atom-sized contacts of Au and Pt, including their single-atom contacts, behave as a pure resistance in the RF regime.

  2. Protein Viability on Au Nanoparticles during an Electrospray and Electrostatic-Force-Directed Assembly Process

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Mao, Shun; Lu, Ganhua; Yu, Kehan; Chen, Junhong

    2010-01-01

    We study the protein viability on Au nanoparticles during an electrospray and electrostatic-force-directed assembly process, through which Au nanoparticle-antibody conjugates are assembled onto the surface of carbon nanotubes (CNTs) to fabricate carbon nanotube field-effect transistor (CNTFET) biosensors. Enzyme-linked immunosorbent assay (ELISA) and field-effect transistor (FET) measurements have been used to investigate the antibody activity after the nanoparticle assembly. Upon the introduction of matching antigens, the colored reaction from the ELISA and the change in the electrical characteristic of the CNTFET device confirm that the antibody activity is preserved during the assembly process.

  3. Photo-induced wettability of TiO{sub 2} film with Au buffer layer

    SciTech Connect (OSTI)

    Purkayastha, Debarun Dhar; Sangani, L. D. Varma; Krishna, M. Ghanashyam; Madhurima, V.

    2014-04-24

    The effect of thickness of Au buffer layer (15-25 nm) between TiO{sub 2} film and substrate on the wettability of TiO{sub 2} films is reported. TiO{sub 2} films grown on Au buffer layer have a higher contact angle of 96-;100 as compared to 47.6o for the film grown without buffer layer. The transition from hydrophobicity to hydrophilicity under UV irradiation occurs within 10 min. for the buffer layered films whereas it is almost 30 min. for the film grown without buffer layer. The enhanced photo induced hydrophilicity is shown to be surface energy driven.

  4. PdAgAu alloy with high resistance to corrosion by H{sub 2}S

    SciTech Connect (OSTI)

    Braun, Fernando; Miller, James B.; Gellman, Andrew J.; Tarditi, Ana M.; Fleutot, Benoit; Petro, Kondratyuk, Cornaglia, Laura M

    2012-12-01

    PdAgAu alloy films were prepared on porous stainless steel supports by sequential electroless deposition. Two specific compositions, Pd{sub 83}Ag{sub 2}Au{sub 15} and Pd{sub 74}Ag{sub 14}Au{sub 12}, were studied for their sulfur tolerance. The alloys and a reference Pd foil were exposed to 1000 H{sub 2}S/H{sub 2} at 623 K for periods of 3 and 30 hours. The microstructure, morphology and bulk composition of both nonexposed and H{sub 2}S-exposed samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). XRD and SEM analysis revealed time-dependent growth of a bulk Pd{sub 4}S phase on the Pd foil during H{sub 2}S exposure. In contrast, the PdAgAu ternary alloys displayed the same FCC structure before and after H{sub 2}S exposure. In agreement with the XRD and SEM results, sulfur was not detected in the bulk of either ternary alloy samples by EDS, even after 30 hours of H{sub 2}S exposure. X-ray photoelectron spectroscopy (XPS) depth profiles were acquired for both PdAgAu alloys after 3 and 30 hours of exposure to characterize sulfur contamination near their surfaces. Very low S 2p and S 2s XPS signals were observed at the top-surfaces of the PdAgAu alloys, and those signals disappeared before the etch depth reached ~ 10 nm, even for samples exposed to H{sub 2}S for 30 hours. The depth profile analyses also revealed silver and gold segregation to the surface of the alloys; preferential location of Au on the alloys surface may be related to their resistance to bulk sulfide formation. In preliminary tests, a PdAgAu alloy membrane displayed higher initial H{sub 2} permeability than a similarly prepared pure Pd sample and, consistent with resistance to bulk sulfide formation, lower permeability loss in H{sub 2}S than pure Pd.

  5. Experimental evidences of a large extrinsic spin Hall effect in AuW alloy

    SciTech Connect (OSTI)

    Laczkowski, P.; Rojas-Sánchez, J.-C.

    2014-04-07

    We report an experimental study of a gold-tungsten alloy (7 at. % W concentration in Au host) displaying remarkable properties for spintronics applications using both magneto-transport in lateral spin valve devices and spin-pumping with inverse spin Hall effect experiments. A very large spin Hall angle of about 10% is consistently found using both techniques with the reliable spin diffusion length of 2 nm estimated by the spin sink experiments in the lateral spin valves. With its chemical stability, high resistivity, and small induced damping, this AuW alloy may find applications in the nearest future.

  6. Local structures of polar wurtzites Zn1-xMgxO studied by raman and 67Zn/25Mg NMR spectroscopies and by total neutron scattering

    SciTech Connect (OSTI)

    Proffen, Thomas E; Kim, Yiung- Il; Cadars, Sylvian; Shayib, Ramzy; Feigerle, Charles S; Chmelka, Bradley F; Seshadri, Ram

    2008-01-01

    Research in the area of polar semiconductor heterostructures has been growing rapidly, driven in large part by interest in two-dimensional electron gas (2DEG) systems. 2DEGs are known to form at heterojunction interfaces that bear polarization gradients. They can display extremely high electron mobilities, especially at low temperatures, owing to spatial confinement of carrier motions. Recent reports of 2DEG behaviors in Ga{sub 1-x}Al{sub x}N/GaN and Zn{sub 1-x}Mg{sub x}O/ZnO heterostructures have great significance for the development of quantum Hall devices and novel high-electron-mobility transistors (HEMTs). 2DEG structures are usually designed by interfacing a polar semiconductor with its less or more polar alloys in an epitaxial manner. Since the quality of the 2DEG depends critically on interface perfection, as well as the polarization gradient at the heterojunction, understanding compositional and structural details of the parent and alloy semiconductors is an important component in 2DEG design and fabrication. Zn{sub 1-x}Mg{sub x}O/ZnO is one of the most promising heterostructure types for studies of 2DEGs, due to the large polarization of ZnO, the relatively small lattice mismatch, and the large conduction band offsets in the Zn{sub 1-x}Mg{sub x}O/ZnO heterointerface. Although 2DEG formation in Zn{sub 1-x}Mg{sub x}O/ZnO heterostructures have been researched for some time, a clear understanding of the alloy structure of Zn{sub 1-x}Mg{sub x}O is currently lacking. Here, we conduct a detailed and more precise study of the local structure of Zn{sub 1-x}Mg{sub x}O alloys using Raman and solid-state nuclear magnetic resonance (NMR), in conjunction with neutron diffraction techniques.

  7. An X-ray Absorption Fine Structure study of Au adsorbed onto the non-metabolizing cells of two soil bacterial species

    SciTech Connect (OSTI)

    Song, Zhen; Kenney, Janice P.L.; Fein, Jeremy B.; Bunker, Bruce A.

    2015-02-09

    Gram-positive and Gram-negative bacterial cells can remove Au from Au(III)-chloride solutions, and the extent of removal is strongly pH dependent. In order to determine the removal mechanisms, X-ray Absorption Fine Structure (XAFS) spectroscopy experiments were conducted on non-metabolizing biomass of Bacillus subtilis and Pseudomonas putida with fixed Au(III) concentrations over a range of bacterial concentrations and pH values. X-ray Absorption Near Edge Structure (XANES) and Extended X-ray Absorption Fine Structure (EXAFS) data on both bacterial species indicate that more than 90% of the Au atoms on the bacterial cell walls were reduced to Au(I). In contrast to what has been observed for Au(III) interaction with metabolizing bacterial cells, no Au(0) or Au-Au nearest neighbors were observed in our experimental systems. All of the removed Au was present as adsorbed bacterial surface complexes. For both species, the XAFS data suggest that although Au-chloride-hydroxide aqueous complexes dominate the speciation of Au in solution, Au on the bacterial cell wall is characterized predominantly by binding of Au atoms to sulfhydryl functional groups and amine and/or carboxyl functional groups, and the relative importance of the sulfhydryl groups increases with increasing pH and with decreasing Au loading. The XAFS data for both microorganism species suggest that adsorption is the first step in the formation of Au nanoparticles by bacteria, and the results enhance our ability to account for the behavior of Au in bacteria-bearing geologic systems.

  8. Improving the ethanol gas-sensing properties of porous ZnO microspheres by Co doping

    SciTech Connect (OSTI)

    Xiao, Qi Wang, Tao

    2013-08-01

    Graphical abstract: - Highlights: • Co-doped porous ZnO microspheres were synthesized. • 3 mol% Co-doped ZnO sensor showed the highest response to ethanol. • 3 mol% Co-doped ZnO sensor exhibited fast recovery property. • 3 mol% Co-doped ZnO sensor exhibited good selectivity and long-term stability. - Abstract: Porous Co-doped ZnO microspheres were prepared by a simple hydrothermal method combined with post-annealing. Co species existed as a form of divalent state in the sample and substituted Zn{sup 2+} sites in ZnO crystal lattice, which was affirmed by X-ray diffraction, UV–vis diffuse reflectance spectroscopy and X-ray photoelectron spectroscopy. The gas-sensing measurements demonstrated that the 3 mol% Co-doped ZnO sample showed the highest response value to 100 ppm ethanol at 350 °C, which were 5 folds higher than that of the pure ZnO sample. In addition, the 3 mol% Co-doped ZnO sensor exhibited fast recovery property, good quantitative determination, good selectivity and long-term stability. The superior sensing properties were contributed to high specific surface area combined with the large amount of oxygen vacancies originating from Co doping.

  9. Molecular dynamics simulation of annealed ZnO surfaces

    SciTech Connect (OSTI)

    Min, Tjun Kit; Yoon, Tiem Leong; Lim, Thong Leng

    2015-04-24

    The effect of thermally annealing a slab of wurtzite ZnO, terminated by two surfaces, (0001) (which is oxygen-terminated) and (0001{sup ¯}) (which is Zn-terminated), is investigated via molecular dynamics simulation by using reactive force field (ReaxFF). We found that upon heating beyond a threshold temperature of ∼700 K, surface oxygen atoms begin to sublimate from the (0001) surface. The ratio of oxygen leaving the surface at a given temperature increases as the heating temperature increases. A range of phenomena occurring at the atomic level on the (0001) surface has also been explored, such as formation of oxygen dimers on the surface and evolution of partial charge distribution in the slab during the annealing process. It was found that the partial charge distribution as a function of the depth from the surface undergoes a qualitative change when the annealing temperature is above the threshold temperature.

  10. Low temperature fabrication and doping concentration analysis of Au/Sb ohmic contacts to n-type Si

    SciTech Connect (OSTI)

    Liu, J. Q.; Wang, C.; Zhu, T.; Wu, W. J.; Fan, J.; Tu, L. C.

    2015-11-15

    This paper investigates low temperature ohmic contact formation of Au/Sb to n-type Si substrates through AuSb/NiCr/Au metal stacks. Liquid epitaxy growth is utilized to incorporate Sb dopants into Si substrate in AuSi melt. The best specific contact resistivity achieved is 0.003 Ω ⋅ cm{sup 2} at 425 {sup o}C. Scanning electron microscopy (SEM) reveals inverted pyramidal crater regions at the metal/semiconductor interface, indicating that AuSi alloying efficiently occurs at such sites. Secondary ion mass spectroscopy (SIMS) shows that Sb atoms are successfully incorporated into Si as doping impurities during the anneal process, and the Sb doping concentration at the contact interface is found to be higher than the solid solubility limit in a Si crystal. This ohmic contacts formation method is suitable for semiconductor fabrication processes with limited thermal budget, such as post CMOS integration of MEMS.

  11. Field emission properties of ZnO nanosheet arrays

    SciTech Connect (OSTI)

    Naik, Kusha Kumar; Rout, Chandra Sekhar E-mail: dj.late@ncl.res.in E-mail: csrout@iitbbs.ac.in; Khare, Ruchita; More, Mahendra A.; Chakravarty, Disha; Late, Dattatray J. E-mail: dj.late@ncl.res.in E-mail: csrout@iitbbs.ac.in; Thapa, Ranjit E-mail: dj.late@ncl.res.in E-mail: csrout@iitbbs.ac.in

    2014-12-08

    Electron emission properties of electrodeposited ZnO nanosheet arrays grown on Indium tin oxide coated glass substrates have been studied. Influence of oxygen vacancies on electronic structures and field emission properties of ZnO nanosheets are investigated using density functional theory. The oxygen vacancies produce unshared d electrons which form an impurity energy state; this causes shifting of Fermi level towards the vacuum, and so the barrier energy for electron extraction reduces. The ZnO nanosheet arrays exhibit a low turn-on field of 2.4 V/μm at 0.1 μA/cm{sup 2} and current density of 50.1 μA/cm{sup 2} at an applied field of 6.4 V/μm with field enhancement factor, β = 5812 and good field emission current stability. The nanosheet arrays grown by a facile electrodeposition process have great potential as robust high performance vertical structure electron emitters for future flat panel displays and vacuum electronic device applications.

  12. Coulomb Excitation of the N = 50 nucleus {sup 80}Zn

    SciTech Connect (OSTI)

    Van de Walle, J.; Cocolios, T. E.; Huyse, M.; Ivanov, O.; Mayet, P.; Raabe, R.; Sawicka, M.; Stefanescu, I.; Duppen, P. van; Aksouh, F.; Behrens, T.; Gernhauser, R.; Kroell, T.; Kruecken, R.; Bildstein, V.; Blazhev, A.; Eberth, J.

    2008-05-12

    Neutron rich Zinc isotopes, including the N = 50 nucleus {sup 80}Zn, were produced and post-accelerated at the Radioactive Ion Beam (RIB) facility REX-ISOLDE (CERN). Low-energy Coulomb excitation was induced on these isotopes after post-acceleration, yielding B(E2) strengths to the first excited 2{sup +} states. For the first time, an excited state in {sup 80}Zn was observed and the 2{sub 1}{sup +} state in {sup 78}Zn was established. The measured B(E2,2{sub 1}{sup +}{yields}0{sub 1}{sup +}) values are compared to two sets of large scale shell model calculations. Both calculations reproduce the observed B(E2) systematics for the full Zinc isotopic chain. The results for N = 50 isotones indicate a good N = 50 shell closure and a strong Z = 28 proton core polarization. The new results serve as benchmarks to establish theoretical models, predicting the nuclear properties of the doubly magic nucleus {sup 78}Ni.

  13. Yields of photoneutron reactions on {sup 197}Au nuclei in the giant-dipole-resonance region

    SciTech Connect (OSTI)

    Belyshev, S. S.; Ermakov, A. N.; Ishkhanov, B. S.; Kuznetsov, A. A.; Kurilik, A. S.; Stopani, K. A.; Troschiev, S. Yu.

    2011-11-15

    Yields of photonuclear reactions on 197Au nuclei were measured in a beam of bremsstrahlung photons, the endpoint energy of the bremsstrahlung spectrum being 29.1 MeV. These measurements were performed by means of the gamma-activation procedure. The results obtained in this way were compared with the results of earlier experiments and theoretical calculations.

  14. Plasmon-enhanced reverse water gas shift reaction over oxide supported Au catalysts

    SciTech Connect (OSTI)

    Upadhye, AA; Ro, I; Zeng, X; Kim, HJ; Tejedor, I; Anderson, MA; Dumesic, JA; Huber, GW

    2015-01-01

    We show that localized surface plasmon resonance (LSPR) can enhance the catalytic activities of different oxide-supported Au catalysts for the reverse water gas shift (RWGS) reaction. Oxide-supported Au catalysts showed 30 to 1300% higher activity for RWGS under visible light compared to dark conditions. Au/TiO2 catalyst prepared by the deposition-precipitation (DP) method with 3.5 nm average Au particle size showed the highest activity for the RWGS reaction. Visible light is converted into chemical energy for this reaction with up to a 5% overall efficiency. A shift in the apparent activation energy (from 47 kJ mol(-1) in dark to 35 kJ mol(-1) in light) and apparent reaction order with respect to CO2 (from 0.5 in dark to 1.0 in light) occurs due to the LSPR. Our kinetic results indicate that the LSPR increases the rate of either the hydroxyl hydrogenation or carboxyl decomposition more than any other steps in the reaction network.

  15. The effect of alkali metal on the surface properties of potassium doped Au-Beta zeolites

    SciTech Connect (OSTI)

    Sobczak, Izabela; Rydz, Michal; Ziolek, Maria

    2013-02-15

    Graphical abstract: Display Omitted Highlights: ► Interaction of gold with K leads to the change of electronic state and redox properties of gold. ► The amount of potassium incorporated into Au-zeolites determines the size of gold particles. ► K(0.2 wt.%)/Au-Beta exhibits the best performance in decomposition of N{sub 2}O and removal of Bu{sub 2}S. -- Abstract: Beta zeolite was applied as support for gold introduced by gold-precipitation method and potassium added by impregnation or adsorption. The effect of zeolite composition and the amount of potassium introduced on the surface properties of the final materials was considered. Moreover, the interaction of gold and potassium species was found to be related to the adsorptive and catalytic behaviour of zeolites in NO reduction with propene and deodorization. K/Au-Beta(Impregnated) exhibits the best performance in the above mentioned processes because of the small gold particles (between 2 and 5 nm) and interaction of gold with potassium species leading to the change of electronic properties of the surface (the appearance of cationic gold species). Potassium added as a promoter improves the catalytic properties of Au-zeolite in N{sub 2}O decomposition and also in deodorization (increase of the ability to dibutyl sulphide oxidation). The catalysts prepared were characterized by XRD, XPS, UV–vis, TEM, pyridine adsorption combined with FTIR and test reaction (2-propanol transformation).

  16. Thermal stability of bimetallic Au/Fe nanoparticles in silica matrix

    SciTech Connect (OSTI)

    Pannu, Compesh Singh, Udai B. Hooda, Sonu Kabiraj, D. Avasthi, D. K.

    2014-04-24

    Thin silica film containing Au and Fe bimetallic nanoparticles were prepared by atom beam cosputtering. The samples were annealed at different temperatures from 400 to 800° C to study the thermal stability of bimetallic nanoparticles using X ray diffraction. It is observed that at 800° C strong structural rearrangement took place leading to thermal decomposition of bimetallic nanoparticles.

  17. Nuclear matter effects on J/? production in asymmetric Cu + Au collisions at \\(\\sqrt{s_{\\mathrm{NN}}} = 200\\) GeV

    SciTech Connect (OSTI)

    Adare, A.; Aidala, C.; Ajitanand, N. N.; Akiba, Y.; Akimoto, R.; Alexander, J.; Alfred, M.; Aoki, K.; Apadula, N.; Aramaki, Y.; Asano, H.; Atomssa, E. T.; Awes, T. C.; Azmoun, B.; Babintsev, V.; Bai, M.; Bai, X.; Bandara, N. S.; Bannier, B.; Barish, K. N.; Bathe, S.; Baublis, V.; Baumann, C.; Baumgart, S.; Bazilevsky, A.; Beaumier, M.; Beckman, S.; Belmont, R.; Berdnikov, A.; Berdnikov, Y.; Bing, X.; Black, D.; Blau, D. S.; Bok, J. S.; Boyle, K.; Brooks, M. L.; Bryslawskyj, J.; Buesching, H.; Bumazhnov, V.; Butsyk, S.; Campbell, S.; Chen, C. -H.; Chi, C. Y.; Chiu, M.; Choi, I. J.; Choi, J. B.; Choi, S.; Christiansen, P.; Chujo, T.; Cianciolo, V.; Citron, Z.; Cole, B. A.; Cronin, N.; Crossette, N.; Csand, M.; Csrg?, T.; Datta, A.; Daugherity, M. S.; David, G.; DeBlasio, K.; Dehmelt, K.; Denisov, A.; Deshpande, A.; Desmond, E. J.; Ding, L.; Dion, A.; Do, J. H.; Drapier, O.; Drees, A.; Drees, K. A.; Durham, J. M.; Durum, A.; D'Orazio, L.; Engelmore, T.; Enokizono, A.; En'yo, H.; Esumi, S.; Eyser, K. O.; Fadem, B.; Feege, N.; Fields, D. E.; Finger, M.; Finger, M.; Fleuret, F.; Fokin, S. L.; Frantz, J. E.; Franz, A.; Frawley, A. D.; Fukao, Y.; Gainey, K.; Gal, C.; Gallus, P.; Garg, P.; Garishvili, A.; Garishvili, I.; Ge, H.; Giordano, F.; Glenn, A.; Gong, X.; Gonin, M.; Goto, Y.; Granier de Cassagnac, R.; Grau, N.; Greene, S. V.; Grosse Perdekamp, M.; Gu, Y.; Gunji, T.; Guragain, H.; Hachiya, T.; Haggerty, J. S.; Hahn, K. I.; Hamagaki, H.; Han, S. Y.; Hanks, J.; Hasegawa, S.; Hashimoto, K.; Hayano, R.; He, X.; Hemmick, T. K.; Hester, T.; Hill, J. C.; Hollis, R. S.; Homma, K.; Hong, B.; Hoshino, T.; Huang, J.; Huang, S.; Ichihara, T.; Ikeda, Y.; Imai, K.; Imazu, Y.; Inaba, M.; Iordanova, A.; Isenhower, D.; Isinhue, A.; Ivanishchev, D.; Jacak, B. V.; Jeon, S. J.; Jezghani, M.; Jia, J.; Jiang, X.; Johnson, B. M.; Joo, E.; Joo, K. S.; Jouan, D.; Jumper, D. S.; Kamin, J.; Kanda, S.; Kang, B. H.; Kang, J. H.; Kang, J. S.; Kapustinsky, J.; Kawall, D.; Kazantsev, A. V.; Key, J. A.; Khachatryan, V.; Khandai, P. K.; Khanzadeev, A.; Kihara, K.; Kijima, K. M.; Kim, C.; Kim, D. H.; Kim, D. J.; Kim, E. -J.; Kim, H. -J.; Kim, M.; Kim, Y. -J.; Kim, Y. K.; Kistenev, E.; Klatsky, J.; Kleinjan, D.; Kline, P.; Koblesky, T.; Kofarago, M.; Komkov, B.; Koster, J.; Kotchetkov, D.; Kotov, D.; Krizek, F.; Kurita, K.; Kurosawa, M.; Kwon, Y.; Lacey, R.; Lai, Y. S.; Lajoie, J. G.; Lebedev, A.; Lee, D. M.; Lee, G. H.; Lee, J.; Lee, K. B.; Lee, K. S.; Lee, S. H.; Leitch, M. J.; Leitgab, M.; Lewis, B.; Li, X.; Lim, S. H.; Liu, M. X.; Lynch, D.; Maguire, C. F.; Makdisi, Y. I.; Makek, M.; Manion, A.; Manko, V. I.; Mannel, E.; Maruyama, T.; McCumber, M.; McGaughey, P. L.; McGlinchey, D.; McKinney, C.; Meles, A.; Mendoza, M.; Meredith, B.; Miake, Y.; Mibe, T.; Mignerey, A. C.; Miller, A. J.; Milov, A.; Mishra, D. K.; Mitchell, J. T.; Miyasaka, S.; Mizuno, S.; Mohanty, A. K.; Montuenga, P.; Moon, T.; Morrison, D. P.; Moskowitz, M.; Moukhanova, T. V.; Murakami, T.; Murata, J.; Mwai, A.; Nagae, T.; Nagamiya, S.; Nagle, J. L.; Nagy, M. I.; Nakagawa, I.; Nakagomi, H.; Nakamiya, Y.; Nakamura, K. R.; Nakamura, T.; Nakano, K.; Nattrass, C.; Netrakanti, P. K.; Nihashi, M.; Niida, T.; Nouicer, R.; Novak, T.; Novitzky, N.; Nyanin, A. S.; O'Brien, E.; Ogilvie, C. A.; Oide, H.; Okada, K.; Orjuela Koop, J. D.; Oskarsson, A.; Ozaki, H.; Ozawa, K.; Pak, R.; Pantuev, V.; Papavassiliou, V.; Park, I. H.; Park, S.; Park, S. K.; Pate, S. F.; Patel, L.; Patel, M.; Peng, J. -C.; Perepelitsa, D. V.; Perera, G. D. N.; Peressounko, D. Yu.; Perry, J.; Petti, R.; Pinkenburg, C.; Pinson, R.; Pisani, R. P.; Purschke, M. L.; Qu, H.; Rak, J.; Ravinovich, I.; Read, K. F.; Reynolds, D.; Riabov, V.; Riabov, Y.; Richardson, E.; Riveli, N.; Roach, D.; Rolnick, S. D.; Rosati, M.; Rowan, Z.; Rubin, J. G.; Ryu, M. S.; Sahlmueller, B.; Saito, N.; Sakaguchi, T.; Sako, H.; Samsonov, V.; Sarsour, M.; Sato, S.; Sawada, S.; Schaefer, B.; Schmoll, B. K.; Sedgwick, K.; Seele, J.; Seidl, R.; Sekiguchi, Y.; Sen, A.; Seto, R.; Sett, P.; Sexton, A.; Sharma, D.; Shaver, A.; Shein, I.; Shibata, T. -A.; Shigaki, K.; Shimomura, M.; Shoji, K.; Shukla, P.; Sickles, A.; Silva, C. L.; Silvermyr, D.; Singh, B. K.; Singh, C. P.; Singh, V.; Skolnik, M.; Slune?ka, M.; Solano, S.; Soltz, R. A.; Sondheim, W. E.; Sorensen, S. P.; Soumya, M.; Sourikova, I. V.; Stankus, P. W.; Steinberg, P.; Stenlund, E.; Stepanov, M.; Ster, A.; Stoll, S. P.; Stone, M. R.; Sugitate, T.; Sukhanov, A.; Sumita, T.; Sun, J.; Sziklai, J.; Takahara, A.; Taketani, A.; Tanida, K.; Tannenbaum, M. J.; Tarafdar, S.; Taranenko, A.; Tennant, E.; Timilsina, A.; Todoroki, T.; Tomek, M.; Torii, H.; Towell, M.; Towell, R.; Towell, R. S.; Tserruya, I.; van Hecke, H. W.; Vargyas, M.; Vazquez-Zambrano, E.; Veicht, A.; Velkovska, J.; Vrtesi, R.; Virius, M.; Vrba, V.

    2014-12-18

    We report on J/? production from asymmetric Cu+Au heavy-ion collisions at \\(\\sqrt{s_{\\mathrm{NN}}} = 200\\) GeV at the Relativistic Heavy Ion Collider at both forward (Cu-going direction) and backward (Au-going direction) rapidities. The nuclear modification of J/? yields in Cu+Au collisions in the Au-going direction is found to be comparable to that in Au+Au collisions when plotted as a function of the number of participating nucleons. In the Cu-going direction, J/? production shows a stronger suppression. This difference is comparable in magnitude and has the same sign as the difference expected from shadowing effects due to stronger low-x gluon suppression in the larger Au nucleus. Thus, the relative suppression is opposite to that expected from hot nuclear matter dissociation, since a higher energy density is expected in the Au-going direction.

  18. Nuclear matter effects on J/ψ production in asymmetric Cu + Au collisions at \\(\\sqrt{s_{\\mathrm{NN}}} = 200\\) GeV

    SciTech Connect (OSTI)

    Adare, A.; Aidala, C.; Ajitanand, N. N.; Akiba, Y.; Akimoto, R.; Alexander, J.; Alfred, M.; Aoki, K.; Apadula, N.; Aramaki, Y.; Asano, H.; Atomssa, E. T.; Awes, T. C.; Azmoun, B.; Babintsev, V.; Bai, M.; Bai, X.; Bandara, N. S.; Bannier, B.; Barish, K. N.; Bathe, S.; Baublis, V.; Baumann, C.; Baumgart, S.; Bazilevsky, A.; Beaumier, M.; Beckman, S.; Belmont, R.; Berdnikov, A.; Berdnikov, Y.; Bing, X.; Black, D.; Blau, D. S.; Bok, J. S.; Boyle, K.; Brooks, M. L.; Bryslawskyj, J.; Buesching, H.; Bumazhnov, V.; Butsyk, S.; Campbell, S.; Chen, C. -H.; Chi, C. Y.; Chiu, M.; Choi, I. J.; Choi, J. B.; Choi, S.; Christiansen, P.; Chujo, T.; Cianciolo, V.; Citron, Z.; Cole, B. A.; Cronin, N.; Crossette, N.; Csanád, M.; Csörgő, T.; Datta, A.; Daugherity, M. S.; David, G.; DeBlasio, K.; Dehmelt, K.; Denisov, A.; Deshpande, A.; Desmond, E. J.; Ding, L.; Dion, A.; Do, J. H.; Drapier, O.; Drees, A.; Drees, K. A.; Durham, J. M.; Durum, A.; D'Orazio, L.; Engelmore, T.; Enokizono, A.; En'yo, H.; Esumi, S.; Eyser, K. O.; Fadem, B.; Feege, N.; Fields, D. E.; Finger, M.; Finger, M.; Fleuret, F.; Fokin, S. L.; Frantz, J. E.; Franz, A.; Frawley, A. D.; Fukao, Y.; Gainey, K.; Gal, C.; Gallus, P.; Garg, P.; Garishvili, A.; Garishvili, I.; Ge, H.; Giordano, F.; Glenn, A.; Gong, X.; Gonin, M.; Goto, Y.; Granier de Cassagnac, R.; Grau, N.; Greene, S. V.; Grosse Perdekamp, M.; Gu, Y.; Gunji, T.; Guragain, H.; Hachiya, T.; Haggerty, J. S.; Hahn, K. I.; Hamagaki, H.; Han, S. Y.; Hanks, J.; Hasegawa, S.; Hashimoto, K.; Hayano, R.; He, X.; Hemmick, T. K.; Hester, T.; Hill, J. C.; Hollis, R. S.; Homma, K.; Hong, B.; Hoshino, T.; Huang, J.; Huang, S.; Ichihara, T.; Ikeda, Y.; Imai, K.; Imazu, Y.; Inaba, M.; Iordanova, A.; Isenhower, D.; Isinhue, A.; Ivanishchev, D.; Jacak, B. V.; Jeon, S. J.; Jezghani, M.; Jia, J.; Jiang, X.; Johnson, B. M.; Joo, E.; Joo, K. S.; Jouan, D.; Jumper, D. S.; Kamin, J.; Kanda, S.; Kang, B. H.; Kang, J. H.; Kang, J. S.; Kapustinsky, J.; Kawall, D.; Kazantsev, A. V.; Key, J. A.; Khachatryan, V.; Khandai, P. K.; Khanzadeev, A.; Kihara, K.; Kijima, K. M.; Kim, C.; Kim, D. H.; Kim, D. J.; Kim, E. -J.; Kim, H. -J.; Kim, M.; Kim, Y. -J.; Kim, Y. K.; Kistenev, E.; Klatsky, J.; Kleinjan, D.; Kline, P.; Koblesky, T.; Kofarago, M.; Komkov, B.; Koster, J.; Kotchetkov, D.; Kotov, D.; Krizek, F.; Kurita, K.; Kurosawa, M.; Kwon, Y.; Lacey, R.; Lai, Y. S.; Lajoie, J. G.; Lebedev, A.; Lee, D. M.; Lee, G. H.; Lee, J.; Lee, K. B.; Lee, K. S.; Lee, S. H.; Leitch, M. J.; Leitgab, M.; Lewis, B.; Li, X.; Lim, S. H.; Liu, M. X.; Lynch, D.; Maguire, C. F.; Makdisi, Y. I.; Makek, M.; Manion, A.; Manko, V. I.; Mannel, E.; Maruyama, T.; McCumber, M.; McGaughey, P. L.; McGlinchey, D.; McKinney, C.; Meles, A.; Mendoza, M.; Meredith, B.; Miake, Y.; Mibe, T.; Mignerey, A. C.; Miller, A. J.; Milov, A.; Mishra, D. K.; Mitchell, J. T.; Miyasaka, S.; Mizuno, S.; Mohanty, A. K.; Montuenga, P.; Moon, T.; Morrison, D. P.; Moskowitz, M.; Moukhanova, T. V.; Murakami, T.; Murata, J.; Mwai, A.; Nagae, T.; Nagamiya, S.; Nagle, J. L.; Nagy, M. I.; Nakagawa, I.; Nakagomi, H.; Nakamiya, Y.; Nakamura, K. R.; Nakamura, T.; Nakano, K.; Nattrass, C.; Netrakanti, P. K.; Nihashi, M.; Niida, T.; Nouicer, R.; Novak, T.; Novitzky, N.; Nyanin, A. S.; O'Brien, E.; Ogilvie, C. A.; Oide, H.; Okada, K.; Orjuela Koop, J. D.; Oskarsson, A.; Ozaki, H.; Ozawa, K.; Pak, R.; Pantuev, V.; Papavassiliou, V.; Park, I. H.; Park, S.; Park, S. K.; Pate, S. F.; Patel, L.; Patel, M.; Peng, J. -C.; Perepelitsa, D. V.; Perera, G. D. N.; Peressounko, D. Yu.; Perry, J.; Petti, R.; Pinkenburg, C.; Pinson, R.; Pisani, R. P.; Purschke, M. L.; Qu, H.; Rak, J.; Ravinovich, I.; Read, K. F.; Reynolds, D.; Riabov, V.; Riabov, Y.; Richardson, E.; Riveli, N.; Roach, D.; Rolnick, S. D.; Rosati, M.; Rowan, Z.; Rubin, J. G.; Ryu, M. S.; Sahlmueller, B.; Saito, N.; Sakaguchi, T.; Sako, H.; Samsonov, V.; Sarsour, M.; Sato, S.; Sawada, S.; Schaefer, B.; Schmoll, B. K.; Sedgwick, K.; Seele, J.; Seidl, R.; Sekiguchi, Y.; Sen, A.; Seto, R.; Sett, P.; Sexton, A.; Sharma, D.; Shaver, A.; Shein, I.; Shibata, T. -A.; Shigaki, K.; Shimomura, M.; Shoji, K.; Shukla, P.; Sickles, A.; Silva, C. L.; Silvermyr, D.; Singh, B. K.; Singh, C. P.; Singh, V.; Skolnik, M.; Slunečka, M.; Solano, S.; Soltz, R. A.; Sondheim, W. E.; Sorensen, S. P.; Soumya, M.; Sourikova, I. V.; Stankus, P. W.; Steinberg, P.; Stenlund, E.; Stepanov, M.; Ster, A.; Stoll, S. P.; Stone, M. R.; Sugitate, T.; Sukhanov, A.; Sumita, T.; Sun, J.; Sziklai, J.; Takahara, A.; Taketani, A.; Tanida, K.; Tannenbaum, M. J.; Tarafdar, S.; Taranenko, A.; Tennant, E.; Timilsina, A.; Todoroki, T.; Tomášek, M.; Torii, H.; Towell, M.; Towell, R.; Towell, R. S.; Tserruya, I.; van Hecke, H. W.; Vargyas, M.; Vazquez-Zambrano, E.; Veicht, A.; Velkovska, J.; Vértesi, R.; Virius, M.; Vrba, V.; Vznuzdaev, E.; Wang, X. R.; Watanabe, D.; Watanabe, K.; Watanabe, Y.; Watanabe, Y. S.; Wei, F.; Whitaker, S.; Wolin, S.; Woody, C. L.; Wysocki, M.; Xia, B.; Xue, L.; Yalcin, S.; Yamaguchi, Y. L.; Yanovich, A.; Yokkaichi, S.; Yoon, I.; You, Z.; Younus, I.; Yushmanov, I. E.; Zajc, W. A.; Zelenski, A.; Zhou, S.

    2014-12-18

    We report on J/ψ production from asymmetric Cu+Au heavy-ion collisions at \\(\\sqrt{s_{\\mathrm{NN}}} = 200\\) GeV at the Relativistic Heavy Ion Collider at both forward (Cu-going direction) and backward (Au-going direction) rapidities. The nuclear modification of J/ψ yields in Cu+Au collisions in the Au-going direction is found to be comparable to that in Au+Au collisions when plotted as a function of the number of participating nucleons. In the Cu-going direction, J/ψ production shows a stronger suppression. This difference is comparable in magnitude and has the same sign as the difference expected from shadowing effects due to stronger low-x gluon suppression in the larger Au nucleus. Thus, the relative suppression is opposite to that expected from hot nuclear matter dissociation, since a higher energy density is expected in the Au-going direction.

  19. Enhanced photocatalytic performance of Ga{sup 3+}-doped ZnO

    SciTech Connect (OSTI)

    Zhong, Jun Bo; Li, Jian Zhang; Zeng, Jun; He, Xi Yang; Hu, Wei; Shen, Yue Cheng

    2012-11-15

    Graphical abstract: In general, the strong SPS response corresponds to the high separation rate of photoinduced charge carriers on the basis of the SPS principle. The photovoltage of Ga{sup 3+}-doped ZnO is higher than that of ZnO, thus it can be confirmed that the Ga{sup 3+}-doped ZnO has a higher charge separation rate than the ZnO sample. Among these samples, 1%Ga has highest charge separation rate. Display Omitted Highlights: ► Ga{sup 3+} has been employed to dope ZnO photocatalyst. ► Ga{sup 3+} increases the BET surface area and changes the morphology of ZnO. ► The photoinduced charge separation rate has been enhanced. ► The photocatalytic activity has been greatly promoted. -- Abstract: ZnO and Ga{sup 3+}-doped ZnO with different molar ratio of Ga/Zn (1%, 2% and 3%) were prepared by a parallel flow precipitation method. The photocatalysts prepared were characterized by BET surface area, X-ray diffraction (XRD), UV/vis diffuse reflectance spectroscopy (DRS), scanning electron microscope (SEM) and surface photovoltage spectroscopy (SPS), respectively. The results show that doping Ga{sup 3+} into ZnO increases the BET surface area. The XRD spectra of the photocatalysts calcined at 573 K show only the characteristic peaks of wurtzite-type. Ga{sup 3+}-doped ZnO absorbs much more light than ZnO in the visible light region. Doping Ga{sup 3+} into ZnO greatly changes the morphology of ZnO and enhances the photoinduced charge separation rate. The photocatalytic activity of ZnO and Ga{sup 3+}-doped ZnO for decolorization of methyl orange (MO) solution was evaluated, of all the photocatalysts prepared, the Ga{sup 3+}-doped ZnO with 1% possesses the best photocatalytic activity and the possible reason was discussed.

  20. NEW CONSTRAINTS ON COMPANIONS AND DUST WITHIN A FEW AU OF VEGA

    SciTech Connect (OSTI)

    Mennesson, B.; Serabyn, E.; Martin, S. R.; Liewer, K.; Mawet, D.; Hanot, C.

    2011-07-20

    We report on high contrast near-infrared ({approx}2.2 {mu}m) observations of Vega obtained with the Palomar Fiber Nuller, a dual sub-aperture rotating coronagraph installed at the Palomar Hale telescope. The data show consistent astrophysical null depth measurements at the {approx_equal} 10{sup -3} level or below for three different baseline orientations spanning 60 deg in azimuth, with individual 1{sigma} uncertainties {<=}7 x 10{sup -4}. These high cancellation and accuracy levels translate into a dynamic range greater than 1000:1 inside the diffraction limit of the 5 m telescope beam. Such high contrast performance is unprecedented in the near-infrared and provides improved constraints on Vega's immediate ({approx_equal}20 to 250 mas, or {approx_equal}0.15 to 2 AU) environment. In particular, our measurements rule out any potential companion in the [0.25-1 AU] region contributing more than 1% of the overall near-infrared stellar flux, with limits as low as 0.2% near 0.6 AU. These are the best upper limits established so far by direct detection for a companion to Vega in this inner region. We also conclude that any dust population contributing a significant ({>=}1%) near-infrared thermal excess can arise only within 0.2 AU of the star, and that it must consist of much smaller grains than in the solar zodiacal cloud. Dust emission from farther than {approx_equal}2 AU is also not ruled out by our observations, but would have to originate in strong scattering, pointing again to very small grains.

  1. Impact of strain on electronic defects in (Mg,Zn)O thin films

    SciTech Connect (OSTI)

    Schmidt, Florian Müller, Stefan; Wenckstern, Holger von; Benndorf, Gabriele; Pickenhain, Rainer; Grundmann, Marius

    2014-09-14

    We have investigated the impact of strain on the incorporation and the properties of extended and point defects in (Mg,Zn)O thin films by means of photoluminescence, X-ray diffraction, deep-level transient spectroscopy (DLTS), and deep-level optical spectroscopy. The recombination line Y₂, previously detected in ZnO thin films grown on an Al-doped ZnO buffer layer and attributed to tensile strain, was exclusively found in (Mg,Zn)O samples being under tensile strain and is absent in relaxed or compressively strained thin films. Furthermore a structural defect E3´ can be detected via DLTS measurements and is only incorporated in tensile strained samples. Finally it is shown that the omnipresent deep-level E3 in ZnO can only be optically recharged in relaxed ZnO samples.

  2. ZnO:H indium-free transparent conductive electrodes for active-matrix display applications

    SciTech Connect (OSTI)

    Chen, Shuming Wang, Sisi

    2014-12-01

    Transparent conductive electrodes based on hydrogen (H)-doped zinc oxide (ZnO) have been proposed for active-matrix (AM) display applications. When fabricated with optimal H plasma power and optimal plasma treatment time, the resulting ZnO:H films exhibit low sheet resistance of 200 Ω/◻ and high average transmission of 85% at a film thickness of 150 nm. The demonstrated transparent conductive ZnO:H films can potentially replace indium-tin-oxide and serve as pixel electrodes for organic light-emitting diodes as well as source/drain electrodes for ZnO-based thin-film transistors. Use of the proposed ZnO:H electrodes means that two photomask stages can be removed from the fabrication process flow for ZnO-based AM backplanes.

  3. Magnetism in undoped ZnS studied from density functional theory

    SciTech Connect (OSTI)

    Xiao, Wen-Zhi E-mail: llwang@hun.edu.cn; Rong, Qing-Yan; Xiao, Gang; Wang, Ling-ling E-mail: llwang@hun.edu.cn; Meng, Bo

    2014-06-07

    The magnetic property induced by the native defects in ZnS bulk, thin film, and quantum dots are investigated comprehensively based on density functional theory within the generalized gradient approximation + Hubbard U (GGA?+?U) approach. We find the origin of magnetism is closely related to the introduction of hole into ZnS systems. The relative localization of S-3p orbitals is another key to resulting in unpaired p-electron, due to Hund's rule. For almost all the ZnS systems under study, the magnetic moment arises from the S-dangling bonds generated by Zn vacancies. The charge-neutral Zn vacancy, Zn vacancy in 1? charge sate, and S vacancy in the 1+ charge sate produce a local magnetic moment of 2.0, 1.0, and 1.0??{sub B}, respectively. The Zn vacancy in the neutral and 1? charge sates are the important cause for the ferromagnetism in ZnS bulk, with a Curie temperature (T{sub C}) above room temperature. For ZnS thin film with clean (111) surfaces, the spins on each surface are ferromagnetically coupled but antiferromagnetically coupled between two surfaces, which is attributable to the internal electric field between the two polar (111) surfaces of the thin film. Only surface Zn vacancies can yield local magnetic moment for ZnS thin film and quantum dot, which is ascribed to the surface effect. Interactions between magnetic moments on S-3p states induced by hole-doping are responsible for the ferromagnetism observed experimentally in various ZnS samples.

  4. Nucleation and Growth of Electrodeposited ZnO Visualized by in-Situ X-ray

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Microscopy | Stanford Synchrotron Radiation Lightsource Nucleation and Growth of Electrodeposited ZnO Visualized by in-Situ X-ray Microscopy Thursday, June 30, 2016 Electrodeposition (ED) of ZnO has been widely used to deposit transparent conducting films for optoelectronic applications. The film quality, and consequently the performance of the film, is highly dependent on both the nucleation and growth of ZnO. Current studies employ ex-situ experiments where the film is deposited, dried,

  5. Organic Molecule Functionalized Zn3P2 Nanowire Inorganic-Organic...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Organic Molecule Functionalized Zn3P2 Nanowire Inorganic-Organic Hybrid Thermoelectrics Demonstrates self-catalytic schemes for large-scale synthesis of compound semiconductor ...

  6. Green synthesis of graphene nanosheets/ZnO composites and electrochemical properties

    SciTech Connect (OSTI)

    Wang Jun; Gao Zan; Li Zhanshuang; Wang Bin; Yan Yanxia; Liu Qi; Mann, Tom; Zhang Milin; Jiang Zhaohua

    2011-06-15

    A green and facile approach was demonstrated to prepare graphene nanosheets/ZnO (GNS/ZnO) composites for supercapacitor materials. Glucose, as a reducing agent, and exfoliated graphite oxide (GO), as precursor, were used to synthesize GNS, then ZnO directly grew onto conducting graphene nanosheets as electrode materials. The small ZnO particles successfully anchored onto graphene sheets as spacers to keep the neighboring sheets separate. The electrochemical performances of these electrodes were analyzed by cyclic voltammetry, electrochemical impedance spectrometry and chronopotentiometry. Results showed that the GNS/ZnO composites displayed superior capacitive performance with large capacitance (62.2 F/g), excellent cyclic performance, and maximum power density (8.1 kW/kg) as compared with pure graphene electrodes. Our investigation highlight the importance of anchoring of small ZnO particles on graphene sheets for maximum utilization of electrochemically active ZnO and graphene for energy storage application in supercapacitors. - Graphical abstract: Glucose was used to synthesize GNS, then ZnO directly grew onto conducting graphene nanosheets as electrode materials for supercapacitor. Results showed that the composites have superior capacitive performance. Highlights: > Graphene nanosheets were synthesized via using glucose as a reducing agent. > The reductant and the oxidized product are environmentally friendly. > ZnO grew onto conducting graphene sheets keeping neighboring sheets separate. > The structure improves the contact between the electrode and the electrolyte. > Results showed that these composites have good electrochemical property.

  7. Transport and magnetotransport study of Mg doped ZnO thin films

    SciTech Connect (OSTI)

    Agrawal, Arpana; Dar, Tanveer A. Sen, Pratima; Phase, Deodatta M.

    2014-04-14

    We report negative magnetoresistance in pulsed laser deposited single phase ZnO and Mg{sub 0.268}Zn{sub 0.732}O films and attribute it to the presence of oxygen interstitials (O{sub i}) and zinc interstitials (Zn{sub i}) as observed in the X-ray photoelectron spectra of the films. An interesting feature of reduction of negative magnetoresistance at low temperatures and large fields in Mg{sub 0.268}Zn{sub 0.732}O film is observed and is explained by taking into account the localized scattering.

  8. Visible light photocatalytic property of Zn doped V{sub 2}O{sub 5} nanoparticles

    SciTech Connect (OSTI)

    Suresh, R.; Giribabu, K.; Vijayalakshmi, L.; Stephen, A.; Narayanan, V.

    2012-06-05

    The Zn doped V{sub 2}O{sub 5} nanoparticles were synthesized by thermal decomposition method. The prepared samples were characterized by various techniques like Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) studies, UV-Visible spectroscopy (UV-Vis) and field emission scanning electron microscopy (FE-SEM). The photocatalytic activities of pure and Zn doped V{sub 2}O{sub 5} nanoparticles were examined based on the photodegradation of Rhodamine B (RhB). Experimental results indicated that the Zn doped V{sub 2}O{sub 5} photocatalyst (the molar ratio of V to Zn is 99: 1) exhibited maximum photocatalytic activity.

  9. Optical and morphological properties of graphene sheets decorated with ZnO nanowires via polyol enhancement

    SciTech Connect (OSTI)

    Sharma, Vinay, E-mail: winn201@gmail.com; Rajaura, Rajveer Singh, E-mail: winn201@gmail.com [Centre for Converging Technologies, University of Rajasthan, Jaipur - 302004 (India); Sharma, Preetam K.; Srivastava, Subodh; Vijay, Y. K. [Department of Physics, Thin Film and Membrane Science Lab., University of Rajasthan, Jaipur - 302004 (India); Sharma, S. S. [Department of Physics, Govt. Women Engineering College, Ajmer- 305002 (India)

    2014-04-24

    Graphene-ZnO nanocomposites have proven to be very useful materials for photovoltaic and sensor applications. Here, we report a facile, one-step in situ polymerization method for synthesis of graphene sheets randomly decorated with zinc oxide nanowires using ethylene glycol as solvent. We have used hydrothermal treatment for growth of ZnO nanowires. UV-visible spectra peak shifting around 288nm and 307 nm shows the presence of ZnO on graphene structure. Photoluminiscence spectra (PL) in 400nm-500nm region exhibits the luminescence quenching effect. Scanning electron microscopy (SEM) image confirms the growth of ZnO nanowires on graphene sheets.

  10. Metallic filament formation by aligned oxygen vacancies in ZnO-based resistive switches

    SciTech Connect (OSTI)

    Gu, Tingkun

    2014-05-28

    The electronic structure of ZnO with defects of oxygen vacancies were investigated by using first-principles methods. Some structure models were constructed in order to investigate the effects of the distribution of oxygen vacancies on the electronic properties of ZnO. By analyzing the calculated results, we found that only the aligned oxygen vacancies can form the conducting channel in ZnO, and the transformation of the oxygen vacancy from charged state to neutral state is consistent with the energetics rule of the forming aligned oxygen vacancies. As for the heterojunction of Pt/ZnO/Pt, the oxygen vacancies near the interface of Pt/ZnO depress the local Schottky barrier effectively, and the aligned oxygen vacancies in ZnO form a conducting filament connecting two Pt electrodes. The metallic filament formation in Pt/ZnO/Pt resistive switching cells should be closely related to the carrier injection from Pt electrode into ZnO and the arrangement of oxygen vacancies in ZnO slab.

  11. Defects in paramagnetic Co-doped ZnO films studied by transmission electron microscopy

    SciTech Connect (OSTI)

    Kovacs, Andras; Ney, A.; Duchamp, Martial; Ney, V.; Boothroyd, Chris; Galindo, Pedro L.; Kaspar, Tiffany C.; Chambers, Scott A.; Dunin-Borkowski, Rafal

    2013-12-23

    We have studied planar defects in epitaxial Co:ZnO dilute magnetic semiconductor thin films deposited on c-plane sapphire (Al2O3) and the Co:ZnO/Al2O3 interface structure at atomic resolution using aberration-corrected transmission electron microscopy (TEM) and electron energy-loss spectroscopy (EELS). Comparing Co:ZnO samples deposited by pulsed laser deposition and reactive magnetron sputtering, both exhibit extrinsic stacking faults, incoherent interface structures, and compositional variations within the first 3-4 Co:ZnO layers at the interface.. In addition, we have measured the local strain which reveals the lattice distortion around the stacking faults.

  12. Structural Studies of Al:ZnO Powders and Thin Films | Stanford Synchrotron

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Radiation Lightsource Structural Studies of Al:ZnO Powders and Thin Films Monday, June 18, 2012 - 2:00pm SSRL Main Conference Room 137-322 Dr. Bridget Ingham, Associate Investigator, MacDiarmid Institute for Advanced Materials & Nanotechnology Al-doped ZnO (Al:ZnO) is a promising transparent conducting oxide. We have used complementary synchrotron and laboratory techniques to study the incorporation of Al within the ZnO lattice, and measure its effect on the crystallinity of thin films

  13. Analysis of Surface Chemistry and Detector Performance of Chemically Process CdZnTe crystals

    SciTech Connect (OSTI)

    HOSSAIN A.; Yang, G.; Sutton, J.; Zergaw, T.; Babalola, O. S.; Bolotnikov, A. E.; Camarda. ZG. S.; Gul, R.; Roy, U. N., and James, R. B.

    2015-10-05

    The goal is to produce non-conductive smooth surfaces for fabricating low-noise and high-efficiency CdZnTe devices.

  14. Nonlinear optical characterization of ZnS thin film synthesized by chemical spray pyrolysis method

    SciTech Connect (OSTI)

    G, Sreeja V; Anila, E. I. R, Reshmi John, Manu Punnan; V, Sabitha P; Radhakrishnan, P.

    2014-10-15

    ZnS thin film was prepared by Chemical Spray Pyrolysis (CSP) method. The sample was characterized by X-ray diffraction method and Z scan technique. XRD pattern showed that ZnS thin film has hexagonal structure with an average size of about 5.6nm. The nonlinear optical properties of ZnS thin film was studied by open aperture Z-Scan technique using Q-switched Nd-Yag Laser at 532nm. The Z-scan plot showed that the investigated ZnS thin film has saturable absorption behavior. The nonlinear absorption coefficient and saturation intensity were also estimated.

  15. Distinct water activation on polar/non-polar facets of ZnO nanoparticl...

    Office of Scientific and Technical Information (OSTI)

    Distinct water activation on polarnon-polar facets of ZnO nanoparticles This content will become publicly available on September 14, 2017 Title: Distinct water activation on ...

  16. A Novel and Functional Single Layer Sheet of ZnSe (Journal Article...

    Office of Scientific and Technical Information (OSTI)

    A Novel and Functional Single Layer Sheet of ZnSe Citation ... In this Communication, we report a novel singlelayer sheet ... Type: Accepted Manuscript Journal Name: ACS Applied ...

  17. Synthesis and characterization of ZnO and Ni doped ZnO nanorods by thermal decomposition method for spintronics application

    SciTech Connect (OSTI)

    Saravanan, R.; Santhi, Kalavathy; Sivakumar, N.; Narayanan, V.; Stephen, A.

    2012-05-15

    Zinc oxide nanorods and diluted magnetic semiconducting Ni doped ZnO nanorods were prepared by thermal decomposition method. This method is simple and cost effective. The decomposition temperature of acetate and formation of oxide were determined by TGA before the actual synthesis process. The X-ray diffraction result indicates the single phase hexagonal structure of zinc oxide. The transmission electron microscopy and scanning electron microscopy images show rod like structure of ZnO and Ni doped ZnO samples with the diameter {approx} 35 nm and the length in few micrometers. The surface analysis was performed using X-ray photoelectron spectroscopic studies. The Ni doped ZnO exhibits room temperature ferromagnetism. This diluted magnetic semiconducting Ni doped ZnO nanorods finds its application in spintronics. - Highlights: Black-Right-Pointing-Pointer The method used is very simple and cost effective compared to all other methods for the preparation DMS materials. Black-Right-Pointing-Pointer ZnO and Ni doped ZnO nanorods Black-Right-Pointing-Pointer Ferromagnetism at room temperature.

  18. Controlled fabrication and tunable photoluminescence properties of Mn{sup 2+} doped grapheneZnO composite

    SciTech Connect (OSTI)

    Luan, Xinglong; Zhang, Yihe Tong, Wangshu; Shang, Jiwu; An, Qi; Huang, Hongwei

    2014-11-15

    Highlights: GrapheneZnO composites were synthesized by a mixed solvothermal method. ZnO quantum dots are distributed uniformly on the graphene sheets. A possible hypothesis is raised for the influence of graphene oxide on the nucleation of ZnO. Mn{sup 2+} doped grapheneZnO composites were fabricated and the emission spectra can be tuned by doping. - Abstract: GrapheneZnO composites (GZnO) with controlled morphology and photoluminescence property were synthesized by a mixed solvothermal method. Mixed solvent were composed by dimethyl sulfoxide and ethylene glycol. Fourier transform infrared spectroscopy, transmission electron microscopy and photoluminescence spectra were used to characterize GZnO. Graphene as a substrate can help the distribution and the dispersity of ZnO, and a possible model of the interaction between graphene oxide and ZnO particles is proposed. At the same time, graphene also reduce the size of ZnO particles to about 5 nm. Furthermore, Mn{sup 2+} ions dopes GZnO successfully by the mixed solvothermal synthesis and the doping of Mn{sup 2+} makes GZnO shift red from 465 nm to 548 nm and 554 nm in the emission spectrum. The changes of the emission spectrum by the adding of Mn{sup 2+} make GZnO have tunable photoluminescence spectrum which is desirable for practical applications.

  19. Structural Stability and Defect Energetics of ZnO from Diffusion Quantum Monte Carlo

    SciTech Connect (OSTI)

    Santana Palacio, Juan A.; Krogel, Jaron T.; Kim, Jeongnim; Kent, Paul R.; Reboredo, Fernando A.

    2015-04-28

    We have applied the many-body ab-initio diffusion quantum Monte Carlo (DMC) method to study Zn and ZnO crystals under pressure, and the energetics of the oxygen vacancy, zinc interstitial and hydrogen impurities in ZnO. We show that DMC is an accurate and practical method that can be used to characterize multiple properties of materials that are challenging for density functional theory approximations. DMC agrees with experimental measurements to within 0.3 eV, including the band-gap of ZnO, the ionization potential of O and Zn, and the atomization energy of O2, ZnO dimer, and wurtzite ZnO. DMC predicts the oxygen vacancy as a deep donor with a formation energy of 5.0(2) eV under O-rich conditions and thermodynamic transition levels located between 1.8 and 2.5 eV from the valence band maximum. Our DMC results indicate that the concentration of zinc interstitial and hydrogen impurities in ZnO should be low under n-type, and Zn- and H-rich conditions because these defects have formation energies above 1.4 eV under these conditions. Comparison of DMC and hybrid functionals shows that these DFT approximations can be parameterized to yield a general correct qualitative description of ZnO. However, the formation energy of defects in ZnO evaluated with DMC and hybrid functionals can differ by more than 0.5 eV.

  20. Structural Stability and Defect Energetics of ZnO from Diffusion Quantum Monte Carlo

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Santana Palacio, Juan A.; Krogel, Jaron T.; Kim, Jeongnim; Kent, Paul R.; Reboredo, Fernando A.

    2015-04-28

    We have applied the many-body ab-initio diffusion quantum Monte Carlo (DMC) method to study Zn and ZnO crystals under pressure, and the energetics of the oxygen vacancy, zinc interstitial and hydrogen impurities in ZnO. We show that DMC is an accurate and practical method that can be used to characterize multiple properties of materials that are challenging for density functional theory approximations. DMC agrees with experimental measurements to within 0.3 eV, including the band-gap of ZnO, the ionization potential of O and Zn, and the atomization energy of O2, ZnO dimer, and wurtzite ZnO. DMC predicts the oxygen vacancy asmore » a deep donor with a formation energy of 5.0(2) eV under O-rich conditions and thermodynamic transition levels located between 1.8 and 2.5 eV from the valence band maximum. Our DMC results indicate that the concentration of zinc interstitial and hydrogen impurities in ZnO should be low under n-type, and Zn- and H-rich conditions because these defects have formation energies above 1.4 eV under these conditions. Comparison of DMC and hybrid functionals shows that these DFT approximations can be parameterized to yield a general correct qualitative description of ZnO. However, the formation energy of defects in ZnO evaluated with DMC and hybrid functionals can differ by more than 0.5 eV.« less

  1. Centrality dependence of low-momentum direct-photon production in Au+Au collisions at ?sNN = 200 GeV

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Adare, A.

    2015-06-05

    The PHENIX experiment at RHIC has measured the centrality dependence of the direct photon yield from Au+Au collisions at ?sNN = 200 GeV down to pT = 0.4 GeV/c. Photons are detected via photon conversions to e?e? pairs and an improved technique is applied that minimizes the systematic uncertainties that usually limit direct photon measurements, in particular at low pT . We find an excess of direct photons above the Ncoll-scaled yield measured in p+p collisions. This excess yield is well described by an exponential distribution with an inverse slope of about 240 MeV/c in the pT range from 0.62.0moreGeV/c. While the shape of the pT distribution is independent of centrality within the experimental uncertainties, the yield increases rapidly with increasing centrality, scaling approximately with N ? part, where ? = 1.380.03(stat)0.07(syst).less

  2. Centrality dependence of low-momentum direct-photon production in Au+Au collisions at sNN=200 GeV

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Adare, A.; Afanasiev, S.; Aidala, C.; Ajitanand, N. N.; Akiba, Y.; Akimoto, R.; Al-Bataineh, H.; Al-Ta'ani, H.; Alexander, J.; Angerami, A.; et al

    2015-06-05

    The PHENIX experiment at RHIC has measured the centrality dependence of the direct photon yield from Au+Au collisions at √sNN = 200 GeV down to pT = 0.4 GeV/c. Photons are detected via photon conversions to e⁺e⁻ pairs and an improved technique is applied that minimizes the systematic uncertainties that usually limit direct photon measurements, in particular at low pT . We find an excess of direct photons above the Ncoll-scaled yield measured in p+p collisions. This excess yield is well described by an exponential distribution with an inverse slope of about 240 MeV/c in the pT range from 0.6–2.0more »GeV/c. In this study, while the shape of the pT distribution is independent of centrality within the experimental uncertainties, the yield increases rapidly with increasing centrality, scaling approximately with N α part, where α = 1.38±0.03(stat)±0.07(syst).« less

  3. Charged-to-neutral correlation at forward rapidity in Au+Au collisions at sNN=200 GeV

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Adamczyk, L.; Adkins, J. K.; Agakishiev, G.; Aggarwal, M. M.; Ahammed, Z.; Alekseev, I.; Alford, J.; Anson, C. D.; Aparin, A.; Arkhipkin, D.; et al

    2015-03-20

    Event-by-event fluctuations of the ratio of inclusive charged to photon multiplicities at forward rapidity in Au+Au collision at √sNN=200 GeV have been studied. Dominant contribution to such fluctuations is expected to come from correlated production of charged and neutral pions. We search for evidences of dynamical fluctuations of different physical origins. Observables constructed out of moments of multiplicities are used as measures of fluctuations. Mixed events and model calculations are used as baselines. Results are compared to the dynamical net-charge fluctuations measured in the same acceptance. A non-zero statistically significant signal of dynamical fluctuations is observed in excess to themore »model prediction when charged particles and photons are measured in the same acceptance. Thus, we find that, unlike dynamical net-charge fluctuation, charge-neutral fluctuation is not dominated by correlation due to particle decay. Results are compared to the expectations based on the generic production mechanism of pions due to isospin symmetry, for which no significant (« less

  4. Measurement of higher cumulants of net-charge multiplicity distributions in Au+Au collisions at sNN=7.7–200GeV

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Adare, A.; Afanasiev, S.; Aidala, C.; Ajitanand, N. N.; Akiba, Y.; Akimoto, R.; Al-Bataineh, H.; Alexander, J.; Al-Ta'ani, H.; Angerami, A.; et al

    2016-01-19

    Our report presents the measurement of cumulants (Cn,n=1,...,4) of the net-charge distributions measured within pseudorapidity (|η|<0.35) in Au+Au collisions at √sNN=7.7–200GeV with the PHENIX experiment at the Relativistic Heavy Ion Collider. The ratios of cumulants (e.g., C1/C2, C3/C1) of the net-charge distributions, which can be related to volume independent susceptibility ratios, are studied as a function of centrality and energy. These quantities are important to understand the quantum-chromodynamics phase diagram and possible existence of a critical end point. The measured values are very well described by expectation from negative binomial distributions. We do not observe any nonmonotonic behavior in themore » ratios of the cumulants as a function of collision energy. These measured values of C1/C2 and C3/C1 can be directly compared to lattice quantum-chromodynamics calculations and thus allow extraction of both the chemical freeze-out temperature and the baryon chemical potential at each center-of-mass energy. Moreover, the extracted baryon chemical potentials are in excellent agreement with a thermal-statistical analysis model.« less

  5. Centrality dependence of low-momentum direct-photon production in Au+Au collisions at sNN=200 GeV

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Adare, A.; Afanasiev, S.; Aidala, C.; Ajitanand, N. N.; Akiba, Y.; Akimoto, R.; Al-Bataineh, H.; Al-Ta'ani, H.; Alexander, J.; Angerami, A.; et al

    2015-06-05

    The PHENIX experiment at RHIC has measured the centrality dependence of the direct photon yield from Au+Au collisions at √sNN = 200 GeV down to pT = 0.4 GeV/c. Photons are detected via photon conversions to e⁺e⁻ pairs and an improved technique is applied that minimizes the systematic uncertainties that usually limit direct photon measurements, in particular at low pT . We find an excess of direct photons above the Ncoll-scaled yield measured in p+p collisions. This excess yield is well described by an exponential distribution with an inverse slope of about 240 MeV/c in the pT range from 0.6–2.0more » GeV/c. In this study, while the shape of the pT distribution is independent of centrality within the experimental uncertainties, the yield increases rapidly with increasing centrality, scaling approximately with N α part, where α = 1.38±0.03(stat)±0.07(syst).« less

  6. Charged-to-neutral correlation at forward rapidity in Au+Au collisions at sNN=200 GeV

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Adamczyk, L.; Adkins, J. K.; Agakishiev, G.; Aggarwal, M. M.; Ahammed, Z.; Alekseev, I.; Alford, J.; Anson, C. D.; Aparin, A.; Arkhipkin, D.; et al

    2015-03-20

    Event-by-event fluctuations of the ratio of inclusive charged to photon multiplicities at forward rapidity in Au+Au collision at √sNN=200 GeV have been studied. Dominant contribution to such fluctuations is expected to come from correlated production of charged and neutral pions. We search for evidences of dynamical fluctuations of different physical origins. Observables constructed out of moments of multiplicities are used as measures of fluctuations. Mixed events and model calculations are used as baselines. Results are compared to the dynamical net-charge fluctuations measured in the same acceptance. A non-zero statistically significant signal of dynamical fluctuations is observed in excess to themore » model prediction when charged particles and photons are measured in the same acceptance. Thus, we find that, unlike dynamical net-charge fluctuation, charge-neutral fluctuation is not dominated by correlation due to particle decay. Results are compared to the expectations based on the generic production mechanism of pions due to isospin symmetry, for which no significant (< 1%) deviation is observed.« less

  7. Energy dependence of Kπ, pπ and Kp fluctuations in Au+Au collisions from √sNN=7.7 to 200 GeV

    SciTech Connect (OSTI)

    Adamczyk, L.

    2015-08-07

    A search for the quantum chromodynamics (QCD) critical point was performed by the STAR experiment at the Relativistic Heavy Ion Collider, using dynamical fluctuations of unlike particle pairs. Heavy ion collisions were studied over a large range of collision energies with homogeneous acceptance and excellent particle identification, covering a significant range in the QCD phase diagram where a critical point may be located. Dynamical Kπ, pπ, and Kp fluctuations as measured by the STAR experiment in central 0–5% Au+Au collisions from center-of-mass collision energies √sNN=7.7 to 200 GeV are presented. The observable νdyn was used to quantify the magnitude of the dynamical fluctuations in event-by-event measurements of the Kπ, pπ, and Kp pairs. The energy dependences of these fluctuations from central 0–5% Au+Au collisions all demonstrate a smooth evolution with collision energy.

  8. Fine structure on the green band in ZnO

    SciTech Connect (OSTI)

    Reynolds, D. C.; Look, D. C.; Jogai, B.

    2001-06-01

    An emission band at 2.4 eV, called the green band, is observed in most ZnO samples, no matter what growth technique is used. Sometimes this band includes fine structure, which consists mainly of doublets, repeated with a longitudinal-optical-phonon-energy spacing (72 meV). We have developed a vibronic model for the green band, based on transitions from two separate shallow donors to a deep acceptor. The donors, at energies 30 and 60 meV from the conduction-band edge, respectively, are also found from Hall-effect measurements. {copyright} 2001 American Institute of Physics.

  9. The adsorption and reaction of vinyl acetate on Au/Pd(100) alloy surfaces

    SciTech Connect (OSTI)

    Li, Zhenjun [Pacific Northwest National Laboratory (PNNL); Calaza, Florencia C [ORNL; Tysoe, Wilfred [University of Wisconsin, Milwaukee

    2012-01-01

    The surface chemistry of vinyl acetate monomer (VAM) is studied on Au/Pd(100) alloys as a function of alloy composition using temperature-programmed desorption and reflection adsorption infrared spectroscopy. VAM adsorbs weakly on isolated palladium sites on the alloy with a heat of adsorption of ~55 kJ/mol, with the plane of the VAM adsorbed close to parallel to the surface. The majority of the VAM adsorbed on isolated sites desorbs molecularly with only a small portion decomposing. At lower gold coverages (below ~0.5 ML of gold), where palladium palladium bridge sites are present, VAM binds to the surface in a distorted geometry via a rehybridized vinyl group. A larger proportion of this VAM decomposes and this reaction is initiated by C\\O bond scission in the VAM to form adsorbed acetate and vinyl species. The implication of this surface chemistry for VAM synthesis on Au/Pd(100) alloys is discussed.

  10. Self-organization of S adatoms on Au(111): ?3R30 rows at low coverage

    SciTech Connect (OSTI)

    Walen, Holly; Liu, Da -Jiang; Oh, Junepyo; Lim, Hyunseob; Evans, J. W.; Kim, Yousoo; Thiel, P. A.

    2015-07-06

    Using scanning tunneling microscopy, we observe an adlayer structure that is dominated by short rows of S atoms, on unreconstructed regions of a Au(111) surface. This structure forms upon adsorption of low S coverage (less than 0.1 monolayer) on a fully reconstructed cleansurface at 300 K, then cooling to 5 K for observation. The rows adopt one of three orientations that are rotated by 30 from the close-packed directions of the Au(111) substrate, and adjacent S atoms in the rows are separated by ?3 times the surface lattice constant, a. Monte Carlo simulations are performed on lattice-gas models, we derived using a limited cluster expansion based on density functional theory energetics. Furthermore, models which include long-range pairwise interactions (extending to 5a), plus selected trio interactions, successfully reproduce the linear rows of S atoms at reasonable temperatures.

  11. Surface Plasmon Excitation via Au Nanoparticles in CdSe Semiconductor

    SciTech Connect (OSTI)

    Pradhan, A. K.; Konda, R. B.; Mundle, R.; Mustafa, H.; Bamiduro, O.; Roy, U. N.; Cui, Y.; Burger, A.

    2008-10-23

    We present experimental evidence for the large Raman and photoluminescence enhancement in CdSe semiconductor films grown on Si and glass substrates due to excitation of surface plasmon resonances in proximate gold metal nanoparticles deposited on the surface of CdSe film. Heterojunction diodes containing n-CdSe on p-Si semiconductor were fabricated and the surface of the diodes was in situ coated with Au nanoparticles using the ultra-high vacuum pulsed-laser deposition technique. A significant enhancement of the photocurrent was obtained in CdSe/p-Si containing Au nanoparticles on the surface compared to CdSe/p-Si due to the enhanced photo-absorption within the semiconductor by the phenomenon of surface plasmon resonance. These observations suggest a variety of approaches for improving the performance of devices such as photodetectors, photovoltaic, and related devices, including biosensors.

  12. The (111) Surface of NaAu2. Structure, Composition, and Stability

    SciTech Connect (OSTI)

    Kwolek, Emma J.; Widmer, Roland; Gröning, Oliver; Deniz, Okan; Walen, Holly; Yuen, Chad D.; Huang, Wenyu; Schlagel, Deborah L.; Wallingford, Mark; Thiel, Patricia A.

    2014-12-17

    The (111) surface of single-crystal NaAu2 is a model for catalytically active, powdered NaAu2. We prepare and characterize this surface with a broad suite of techniques. Preparation in ultrahigh vacuum consists of the traditional approach of ion bombardment (to remove impurities) and thermal annealing (to restore surface order). Both of these steps cause loss of sodium (Na), and repeated treatments eventually trigger conversion of the surface and near-surface regions to crystalline gold. The bulk has a limited ability to repopulate the surface Na. Under conditions where Na depletion is minimized, electron diffraction patterns are consistent with the bulk-terminated structure, and scanning tunneling microscopy reveals mesa-like features with lateral dimensions of a few tens of nanometers. The tops of the mesas do not possess fine structure characteristic of a periodic lattice, suggesting that the surface layer is disordered under the conditions of these experiments.

  13. Atomic Structure of Au329(SR)84 Faradaurate Plasmonic Nanomolecules

    SciTech Connect (OSTI)

    Kumara, Chanaka; Zuo, Xiaobing; Ilavsky, Jan; Cullen, David; Dass, Amala

    2015-04-03

    To design novel nanomaterials, it is important to precisely control the composition, determine the atomic structure, and manipulate the structure to tune the materials property. Here we present a comprehensive characterization of the material whose composition is Au329(SR)84 precisely, therefore referred to as a nanomolecule. The size homogeneity was shown by electron microscopy, solution X-ray scattering, and mass spectrometry. We proposed its atomic structure to contain the Au260 core using experiments and modeling of a total-scattering-based atomic-pair distribution functional analysis. HAADF-STEM images shows fcc-like 2.0 ± 0.1 nm diameter nanomolecules.

  14. Dynamics of copper-phthalocyanine molecules on Au/Ge(001)

    SciTech Connect (OSTI)

    Sotthewes, K.; Heimbuch, R.; Zandvliet, H. J. W.

    2015-10-07

    Spatially resolved current-time scanning tunneling spectroscopy combined with current-distance spectroscopy has been used to characterize the dynamic behavior of copper-phthalocyanine (CuPc) molecules adsorbed on a Au-modified Ge(001) surface. The analyzed CuPc molecules are adsorbed in a “molecular bridge” configuration, where two benzopyrrole groups (lobes) are connected to a Au-induced nanowire, whereas the other two lobes are connected to the adjacent nanowire. Three types of lobe configurations are found: a bright lobe, a dim lobe, and a fuzzy lobe. The dim and fuzzy lobes exhibit a well-defined switching behavior between two discrete levels, while the bright lobe shows a broad oscillation band. The observed dynamic behavior is induced by electrons that are injected into the LUMO+1 orbital of the CuPc molecule. By precisely adjusting the tip-molecule distance, the switching frequency of the lobes can be tuned accurately.

  15. Plasmonic Based Sensing Using an Array of Au-Metal Oxide Thin Films

    SciTech Connect (OSTI)

    Joy, N.; Rogers, Phillip H.; Nandasiri, Manjula I.; Thevuthasan, Suntharampillai; Carpenter, Michael A.

    2012-12-04

    An optical plasmonic-based sensing array has been developed and tested for the selective and sensitive detection of H2, CO, and NO2 at a temperature of 500C in an oxygen-containing background. The three element sensing array used Au nanoparticles embedded in separate thin films of yttria stabilized zirconia (YSZ), CeO2, and TiO2. A peak in the absorbance spectrum due to a localized surface plasmon resonance (LSPR) on the Au nanoparticles was monitored for each film during gas exposures and showed a blue shift in the peak positions for the reducing gases, H2 and CO, and a red shift for the oxidizing gas NO2. A more in-depth look at the sensing response was performed using the multivariate methods of principal component analysis (PCA) analysis and linear discriminant analysis (LDA) on data from across the entire absorbance spectrum range. Qualitative results from both methods showed good separation between the three analytes for both the full array and the Au-TiO2 sample. Quantification of LDA cluster separation using the Mahalanobis distance showed better cluster separation for the array, but there were some instances with the lowest concentrations where the single Au-TiO2 film had better separation than the array. A second method to quantify cluster separation in LDA space was developed using multidimensional volume analysis of the individual cluster volume, overlapped cluster volume and empty volume between clusters. Compared to the individual sensing elements, the array showed less cluster overlap, smaller cluster volumes, and more space between clusters, all of which were expected for improved separability between the analytes.

  16. The confinement effect on the activity of Au NPs in polyols oxidation

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Villa, Alberto; Wang, Di; Chan-Thaw, Carine E.; Campisi, Sebastiano; Veith, Gabriel M; Vahlas, Constantin

    2016-01-01

    We demonstrate a confinement effect where gold nanoparticles trapped within N-functionalized carbon nanofibers (N-CNFs) are more active for polyol oxidation and promote selectivity towards di-acid products, whereas AuNPs trapped on the surface produce as a major by-product the one derived from C C cleavage. The behaviour of NPs confined inside the N-CNF channels can be attributed to a different, possibly multiple, coordination of glycerol on the active site

  17. Radio observations reveal a smooth circumstellar environment around the extraordinary type Ib supernova 2012au

    SciTech Connect (OSTI)

    Kamble, Atish; Soderberg, Alicia M.; Margutti, Raffaella; Milisavljevic, Dan; Chakraborti, Sayan; Dittmann, Jason; Drout, Maria; Sanders, Nathan; Chomiuk, Laura; Medvedev, Mikhail; Chevalier, Roger; Chugai, Nikolai; Fransson, Claes; Nakar, Ehud

    2014-12-10

    We present extensive radio and X-ray observations of SN 2012au, an energetic, radio-luminous supernova of Type Ib that exhibits multi-wavelength properties bridging subsets of hydrogen-poor superluminous supernovae, hypernovae, and normal core-collapse supernovae. The observations closely follow models of synchrotron emission from a shock-heated circumburst medium that has a wind density profile (??r {sup 2}). We infer a sub-relativistic velocity for the shock wave v ? 0.2 c and a radius of r ? 1.4 10{sup 16}cm at 25 days after the estimated date of explosion. For a wind velocity of 1000 km s{sup 1}, we determine the mass-loss rate of the progenitor to be M-dot =3.610{sup ?6} M{sub ?} yr{sup ?1}, consistent with the estimates from X-ray observations. We estimate the total internal energy of the radio-emitting material to be E ? 10{sup 47} erg, which is intermediate to SN 1998bw and SN 2002ap. The evolution of the radio light curve of SN 2012au is in agreement with its interaction with a smoothly distributed circumburst medium and the absence of stellar shells ejected from previous outbursts out to r ? 10{sup 17} cm from the supernova site. We conclude that the bright radio emission from SN 2012au was not dissimilar from other core-collapse supernovae despite its extraordinary optical properties, and that the evolution of the SN 2012au progenitor star was relatively quiet, marked with a steady mass loss, during the final years preceding explosion.

  18. Synthesis, structural and optical characterization of undoped, N-doped ZnO and co-doped ZnO thin films

    SciTech Connect (OSTI)

    Pathak, Trilok Kumar Kumar, R.; Purohit, L. P.

    2015-05-15

    ZnO, N-doped ZnO and Al-N co-doped ZnO thin films were deposited on ITO coated corning glass by spin coater using sol-gel method. The films were annealed in air at 450°C for one hour. The crystallographic structure and morphology of the films were studied by X-ray diffraction (XRD) and scanning electron microscopy (SEM) respectively. The X-ray diffraction results confirm that the thin films are of wurtzite hexagonal with a very small distortion. The optical properties were investigated by transmission spectra of different films using spectrophotometer (Shimadzu UV-VIS-NIR 3600). The results indicate that the N doped ZnO thin films have obviously enhanced transmittance in visible region. Moreover, the thickness of the films has strong influences on the optical constants.

  19. Hierarchical Ag/ZnO micro/nanostructure: Green synthesis and enhanced photocatalytic performance

    SciTech Connect (OSTI)

    Gao, Shuyan; Jia, Xiaoxia; Yang, Shuxia; Li, Zhengdao; Jiang, Kai

    2011-04-15

    Ag/ZnO metal-semiconductor nanocomposites with hierarchical micro/nanostructure have been prepared by the hydrothermal synthesis in the presence of bovine serum albumin (BSA). The results suggest that this biomolecule-assisted hydrothermal method is an efficient route for the fabrication of Ag/ZnO nanocomposites by using BSA both a shape controller and a reducing agent of Ag{sup +} ions. Moreover, Ag nanoparticles on the ZnO act as electron sinks, improving the separation of photogenerated electrons and holes, increasing the surface hydroxyl contents of ZnO, facilitating trapping the photoinduced electrons and holes to form more active hydroxyl radicals, and thus, enhancing the photocatalytic efficiency of ZnO. This is a good example for the organic combination of green chemistry and functional materials. -- Graphical Abstract: A green strategy is report to construct Ag/ZnO metal-semiconductor nanocomposites with hierarchical micro/nanostructure and enhanced photocatalytic activity. Display Omitted Research highlights: > Hierarchical micro/nanostructured Ag/ZnO nanocomposites have been prepared via a green route. > Ag nanoparticles improve the separation of photogenerated electrons and holes. > This facilitates trapping the photoinduced electrons and holes to form more hydroxyl radicals. Therefore, it enhances the photocatalytic efficiency of ZnO.

  20. Band-gap tailoring of ZnO by means of heavy Al doping

    SciTech Connect (OSTI)

    Sernelius, B.E.; Berggren, K.; Jin, Z.; Hamberg, I.; Granqvist, C.G.

    1988-06-15

    Films of ZnO:Al were produced by weakly reactive dual-target magnetron sputtering. Optical band gaps, evaluated from spectrophotometric data, were widened in proportion to the Al doping. The widening could be quantitatively reconciled with an effective-mass model for n-doped semiconductors, provided the polar character of ZnO was accounted for.

  1. Magnetic and structural properties of Zn doped MnV{sub 2}O{sub 4}

    SciTech Connect (OSTI)

    Shahi, Prashant; Shukla, K. K.; Singh, Rahul; Chatterjee, Sandip; Das, A.; Ghosh, A. K.; Nigam, A. K.

    2014-04-24

    The magnetization, Neutron diffraction and X-ray diffraction of Zn doped MnV{sub 2}O{sub 4} as a function of temperature have been measured. It has been observed, with increase of Zn the non-linear orientation of Mn spins with the V spins will decrease which effectively decrease the structural transition temperature more rapidly than Curie Temperature.

  2. Luminescence dynamics of bound exciton of hydrogen doped ZnO nanowires

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Yoo, Jinkyoung; Yi, Gyu -Chul; Chon, Bonghwan; Joo, Taiha; Wang, Zhehui

    2016-04-11

    In this study, all-optical camera, converting X-rays into visible photons, is a promising strategy for high-performance X-ray imaging detector requiring high detection efficiency and ultrafast detector response time. Zinc oxide is a suitable material for all-optical camera due to its fast radiative recombination lifetime in sub-nanosecond regime and its radiation hardness. ZnO nanostructures have been considered as proper building blocks for ultrafast detectors with spatial resolution in sub-micrometer scale. To achieve remarkable enhancement of luminescence efficiency n-type doping in ZnO has been employed. However, luminescence dynamics of doped ZnO nanostructures have not been thoroughly investigated whereas undoped ZnO nanostructures havemore » been employed to study their luminescence dynamics. Here we report a study of luminescence dynamics of hydrogen doped ZnO nanowires obtained by hydrogen plasma treatment. Hydrogen doping in ZnO nanowires gives rise to significant increase in the near-band-edge emission of ZnO and decrease in averaged photoluminescence lifetime from 300 to 140 ps at 10 K. The effects of hydrogen doping on the luminescent characteristics of ZnO nanowires were changed by hydrogen doping process variables.« less

  3. Optical characteristics of ZnO single crystal grown by the hydrothermal method

    SciTech Connect (OSTI)

    Chen, G. Z.; Yin, J. G. E-mail: yjg@siom.ac.cn; Zhang, L. H.; Zhang, P. X.; Wang, X. Y.; Liu, Y. C.; Zhang, C. L.; Gu, S. L.; Hang, Y.

    2015-12-15

    ZnO single crystals have been grown by the hydrothermal method. Raman scattering and Photoluminescence spectroscopy (PL) have been used to study samples of ZnO that were unannealed or annealed in different ambient gases. It is suggested that the green emission may originate from defects related to copper in our samples.

  4. Ethanol Steam Reforming on Co/CeO2: The Effect of ZnO Promoter...

    Office of Scientific and Technical Information (OSTI)

    Ethanol Steam Reforming on CoCeO2: The Effect of ZnO Promoter Citation Details In-Document Search Title: Ethanol Steam Reforming on CoCeO2: The Effect of ZnO Promoter A series of ...

  5. Mid-Gap Electronic States in Zn1 xMnxO

    SciTech Connect (OSTI)

    Johnson, Claire A.; Kittilstved, Kevin R.; Kaspar, Tiffany C.; Droubay, Timothy C.; Chambers, Scott A.; Salley, G. Mackay; Gamelin, Daniel R.

    2010-09-02

    Electronic absorption, magnetic circular dichroism, photoconductivity, and valence-band X-ray photoelectron (XPS) spectroscopic measurements were performed on epitaxial Zn1 xMnxO films to investigate the origin of the new mid-gap band that appears upon introduction of Mn2+ into the ZnO lattice. Absorption and MCD spectroscopies reveal Mn2+-related intensity at energies below the first excitonic transition of ZnO, tailing well into the visible energy region, with an onset at ~2.2 eV. Photoconductivity measurements show that excitation into this visible band generates mobile charge carriers, consistent with assignment as a Mn2+/3+ photoionization transition. XPS measurements reveal the presence of occupied Mn2+ levels just above the valence-band edge, supporting this assignment. Magnetic circular dichroism measurements additionally show a change in sign and large increase in magnitude of the excitonic Zeeman splitting in Zn1 xMnxO relative to ZnO, suggesting that sp-d exchange in Zn1 xMnxO is not as qualitatively different from those in other II-VI diluted magnetic semiconductors as has been suggested. The singular electronic structure feature of Zn1 xMnxO is its Mn2+/3+ ionization level within the gap, and the influence of this level on other physical properties of Zn1 xMnxO is discussed.

  6. Degradation of ZnO Window Layer for CIGS by Damp-Heat Exposure: Preprint

    SciTech Connect (OSTI)

    Pern, F.J.; To, B.; DeHart, C.; Li, X.; Glick, S. H.; Noufi, R.

    2008-08-01

    This paper summarizes our work with more details and an emphasis on the DH-induced degradation of Al-doped ZnO and Zn1-xMgxO alloys. The other two TCOs, ITO and F:SnO2, are not included here.

  7. Catalytic epoxidation of propene with H2O-O2 reactants on Au/TiO2

    SciTech Connect (OSTI)

    Ojeda, Manuel; Iglesia, Enrique

    2008-11-05

    Au/TiO{sub 2} catalysts form hydroperoxy species from H{sub 2}O-O{sub 2} mixtures at near-ambient temperatures. These species can be used in the selective epoxidation of propene to propylene oxide.

  8. Diffusion of Ag, Au and Cs implants in MAX phase Ti3SiC2 (Journal...

    Office of Scientific and Technical Information (OSTI)

    Title: Diffusion of Ag, Au and Cs implants in MAX phase Ti3SiC2 MAX phases (M: early transition metal; A: elements in group 13 or 14; X: C or N), such as titanium silicon carbide ...

  9. Periodicity, Electronic Structures, and Bonding of Gold Tetrahalides [AuX4](-) (X = F, CI, Br, I, At, Uus)

    SciTech Connect (OSTI)

    Li, Wan-Lu; Li, Yong; Xu, Congqiao; Wang, Xue B.; Vorpagel, Erich R.; Li, Jun

    2015-12-07

    Systematic theoretical and experimental investigations have been performed to understand the periodicity and electronic structures of trivalent-gold halides using gold tetrahalides [AuX4]⁻ anions (X = F, Cl, Br, I, At, Uus). The [AuX4]⁻ (X = Cl, Br, I) anions were produced in gas phase and their negative-ion photoelectron spectra were obtained, which exhibited rich and well-resolved spectral peaks. We calculated the adiabatic as well as vertical electron detachment energies using density functional methods with scalar and spin-orbit coupling relativistic effects. The simulated photoelectron spectra based on these calculations are in good agreement with the experimental spectra. Our results show that the trivalent Au(III) oxidation state becomes progressively less stable while Au(I) is preferred when the halides become heavier along the Period Table. This trend reveals that the oxidation state of metals in complexes can be manipulated through ligand design

  10. Au impact on GaAs epitaxial growth on GaAs (111){sub B} substrates in molecular beam epitaxy

    SciTech Connect (OSTI)

    Liao, Zhi-Ming; Chen, Zhi-Gang; Xu, Hong-Yi; Guo, Ya-Nan; Sun, Wen; Zhang, Zhi; Yang, Lei; Lu, Zhen-Yu; Chen, Ping-Ping; Lu, Wei; Zou, Jin; Centre for Microscopy and Microanalysis, The University of Queensland, St. Lucia, Queensland 4072

    2013-02-11

    GaAs growth behaviour under the presence of Au nanoparticles on GaAs {l_brace}111{r_brace}{sub B} substrate is investigated using electron microscopy. It has been found that, during annealing, enhanced Ga surface diffusion towards Au nanoparticles leads to the GaAs epitaxial growth into {l_brace}113{r_brace}{sub B} faceted triangular pyramids under Au nanoparticles, governed by the thermodynamic growth, while during conventional GaAs growth, growth kinetics dominates, resulting in the flatted triangular pyramids at high temperature and the epitaxial nanowires growth at relatively low temperature. This study provides an insight of Au nanoparticle impact on GaAs growth, which is critical for understanding the formation mechanisms of semiconductor nanowires.

  11. Comparative study of the alloying effect on the initial oxidation of Cu-Au(100) and Cu-Pt(100)

    SciTech Connect (OSTI)

    Luo, Langli; Zhou, Guangwen; Kang, Yihong; Yang, Judith C.; Su, Dong; Stach, Eric A.

    2014-03-24

    Using in situ transmission electron microscopy, we show that the oxidation of the Cu-Au(100) results in the formation of Cu{sub 2}O islands that deeply embed into the Cu-Au substrate while the oxidation of the Cu-Pt(100) leads to the formation of Cu{sub 2}O islands that highly protrude above the Cu-Pt substrate. Their difference is attributed to the different mobilities of Pt and Au in the Cu base alloys for which the sluggish mobility of Pt in Cu results in trapped Pt atoms at the oxide/alloy interface while the faster mobility of Au in Cu leads to enhanced rehomogenization of the alloy composition.

  12. In situ Formation of Highly Conducting Covalent Au-C Contacts for Single-Molecule Junctions

    SciTech Connect (OSTI)

    Cheng, Z.L.; Hybertsen, M.; Skouta, R.; Vazquez, H.; Widawsky, J.R.; Schneebeli, S.; Chen, W.; Breslow, R.; Venkataraman, L.

    2011-06-01

    Charge transport across metal-molecule interfaces has an important role in organic electronics. Typically, chemical link groups such as thiols or amines are used to bind organic molecules to metal electrodes in single-molecule circuits, with these groups controlling both the physical structure and the electronic coupling at the interface. Direct metal-carbon coupling has been shown through C60, benzene and {pi}-stacked benzene but ideally the carbon backbone of the molecule should be covalently bonded to the electrode without intervening link groups. Here, we demonstrate a method to create junctions with such contacts. Trimethyl tin (SnMe{sub 3})-terminated polymethylene chains are used to form single-molecule junctions with a break-junction technique. Gold atoms at the electrode displace the SnMe{sub 3} linkers, leading to the formation of direct Au-C bonded single-molecule junctions with a conductance that is {approx}100 times larger than analogous alkanes with most other terminations. The conductance of these Au-C bonded alkanes decreases exponentially with molecular length, with a decay constant of 0.97 per methylene, consistent with a non-resonant transport mechanism. Control experiments and ab initio calculations show that high conductances are achieved because a covalent Au-C sigma ({sigma}) bond is formed. This offers a new method for making reproducible and highly conducting metal-organic contacts.

  13. LOCAL INTERSTELLAR HYDROGEN'S DISAPPEARANCE AT 1 AU: FOUR YEARS OF IBEX IN THE RISING SOLAR CYCLE

    SciTech Connect (OSTI)

    Saul, Lukas; Rodriguez, Diego; Scheer, Juergen; Wurz, Peter; Bzowski, Maciej; Kubiak, Marzena; Sokol, Justina; Fuselier, Stephen; McComas, Dave; Moebius, Eberhard

    2013-04-20

    NASA's Interstellar Boundary Explorer (IBEX) mission has recently opened a new window on the interstellar medium (ISM) by imaging neutral atoms. One ''bright'' feature in the sky is the interstellar wind flowing into the solar system. Composed of remnants of stellar explosions as well as primordial gas and plasma, the ISM is by no means uniform. The interaction of the local ISM with the solar wind shapes our heliospheric environment with hydrogen being the dominant component of the very local ISM. In this paper, we report on direct sampling of the neutral hydrogen of the local ISM over four years of IBEX observations. The hydrogen wind observed at 1 AU has decreased and nearly disappeared as the solar activity has increased over the last four years; the signal at 1 AU has dropped off in 2012 by a factor of {approx}8 to near background levels. The longitudinal offset has also increased with time presumably due to greater radiation pressure deflecting the interstellar wind. We present longitudinal and latitudinal arrival direction measurements of the bulk flow as measured over four years beginning at near solar minimum conditions. The H distribution we observe at 1 AU is expected to be different from that outside the heliopause due to ionization, photon pressure, gravity, and filtration by interactions with heliospheric plasma populations. These observations provide an important benchmark for modeling of the global heliospheric interaction. Based on these observations we suggest a further course of scientific action to observe neutral hydrogen over a full solar cycle with IBEX.

  14. How the guest molecules in nanoporous Zn(II) metal-organic framework can prevent agglomeration of ZnO nanoparticles

    SciTech Connect (OSTI)

    Moeinian, Maryam; Akhbari, Kamran

    2015-05-15

    The host and the apohost framework of [Zn{sub 2}(BDC){sub 2}(H{sub 2}O){sub 2}·(DMF){sub 2}]{sub n} (1·2H{sub 2}O·2DMF), (BDC{sup 2−}=benzene-1,4-dicarboxylate and DMF=N,N-Dimethylformamide), were synthesized and subsequently used for preparation of ZnO nanomaterials. With calcination of the host framework of 1·2H{sub 2}O·2DMF, ZnO nanoparticles were obtained. By the same process on the apohost framework of 1, agglomerated nanoparticles of ZnO were formed. These nano-structures were characterized by X-ray powder diffraction (XRD) and Scanning electron microscopy (SEM). These results indicate that with removal of the guest DMF and coordinated H{sub 2}O molecules from the one-dimensional channels of 1·2H{sub 2}O·2DMF, the tendency of nanoparticles to agglomerate increases and the role of this MOF in preparation of ZnO nanoparticles from this precursor was reduced. - Graphical abstract: Nano-porous zinc(II) MOF with guest DMF and coordinated H{sub 2}O molecules has been synthesized and characterized. The host and the apohost framework of it were used for preparation of ZnO nanomaterials. The role of these species in preparation of ZnO nanoparticles from the host framework is probably similar to the role of polymeric stabilizers in formation of nanoparticles. - Highlights: • Nanoparticles of ZnO were fabricated from nanoporous metal-organic framework. • The effect of guest DMF and coordinated H{sub 2}O molecules on this process was studied. • The effect of them in formation nanoparticle is similar to polymeric stabilizers.

  15. Controlled etching of hexagonal ZnO architectures in an alcohol thermal process

    SciTech Connect (OSTI)

    Wu, Junshu [State Key Laboratory of Fine Chemicals, Department of Materials Science and Chemical Engineering, School of Chemical Engineering, Dalian University of Technology, Dalian 116012 (China)] [State Key Laboratory of Fine Chemicals, Department of Materials Science and Chemical Engineering, School of Chemical Engineering, Dalian University of Technology, Dalian 116012 (China); Xue, Dongfeng, E-mail: dfxue@chem.dlut.edu.cn [State Key Laboratory of Fine Chemicals, Department of Materials Science and Chemical Engineering, School of Chemical Engineering, Dalian University of Technology, Dalian 116012 (China)] [State Key Laboratory of Fine Chemicals, Department of Materials Science and Chemical Engineering, School of Chemical Engineering, Dalian University of Technology, Dalian 116012 (China)

    2010-03-15

    An alcohol thermal technique was applied to the controlled growth of hexagonal ZnO architectures via selective chemical etching. ZnO microdisks were produced first under mild alcohol thermal conditions in presence of formamide. Due to a higher surface energy/atomic density of Zn{sup 2+} {l_brace}0 0 0 1{r_brace} than that of the other faces, hexagonal ZnO microring was obtained by selectively etching positive polar surface of disk-like precursor with a high density of planar defects at the center. The selective etching of ZnO is related to its crystallographic characteristics of surface polarity and chemical activities, which opens a new opportunity for the shape-controlled synthesis of wurtzite-structured materials.

  16. Atomic layer deposition of zinc sulfide with Zn(TMHD){sub 2}

    SciTech Connect (OSTI)

    Short, Andrew; Jewell, Leila; Doshay, Sage; Church, Carena; Keiber, Trevor; Bridges, Frank; Carter, Sue; Alers, Glenn

    2013-01-15

    The atomic layer deposition (ALD) of ZnS films with Zn(TMHD){sub 2} and in situ generated H{sub 2}S as precursors was investigated, over a temperature range of 150-375 Degree-Sign C. ALD behavior was confirmed by investigation of growth behavior and saturation curves. The properties of the films were studied with atomic force microscopy, scanning electron microscopy, energy-dispersive x-ray spectroscopy, ultraviolet-visible-infrared spectroscopy, and extended x-ray absorption fine structure. The results demonstrate a film that can penetrate a porous matrix, with a local Zn structure of bulk ZnS, and a band gap between 3.5 and 3.6 eV. The ZnS film was used as a buffer layer in nanostructured PbS quantum dot solar cell devices.

  17. Polymer-ZnO nanocomposites foils and thin films for UV protection

    SciTech Connect (OSTI)

    Shanshool, Haider Mohammed; Yahaya, Muhammad; Abdullah, Ibtisam Yahya [School of Applied Physics, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor (Malaysia); Yunus, Wan Mahmood Mat [Department of Physics, Faculty of Science, University Putra Malaysia, 43400 UPM, Serdang (Malaysia)

    2014-09-03

    The damage of UV radiation on human eye and skin is extensively studied. In the present work, the nanocomposites foils and thin films have been prepared by using casting method and spin coating, respectively. Nanocomposites were prepared by mixing ZnO nanoparticles with Polymethyl methacrylate (PMMA) and Polyvinylidene fluoride (PVDF) as polymer matrix. Different contents of ZnO nanoparticles were used as filler in the nanocomposites. UV-Vis spectra showed very low transmittance in UV region that decreases with increase content of ZnO. PVDF/ZnO samples showed the lowest transmittance. The rough surface of PVDF was observed from SEM image. While a homogeneous dispersion of ZnO nanoparticles in PMMA were indicated by FESEM images.

  18. Emission Properties from ZnO Quantum Dots Dispersed in SiO{sub 2} Matrix

    SciTech Connect (OSTI)

    Panigrahi, Shrabani; Basak, Durga

    2011-07-15

    Dispersion of ZnO quantum dots in SiO{sub 2} matrix has been achieved in two techniques based on StOeber method to form ZnO QDs-SiO{sub 2} nanocomposites. Sample A is formed with random dispersion by adding tetraethyl orthosilicate (TEOS) to an ethanolic solution of ZnO nanoparticles and sample B is formed with a chain-like ordered dispersion by adding ZnO nanoparticles to an already hydrolyzed ethanolic TEOS solution. The photoluminescence spectra of the as-grown nanocomposites show strong emission in the ultraviolet region. When annealed at higher temperature, depending on the sample type, these show strong red or white emission. Interestingly, when the excitation is removed, the orderly dispersed ZnO QDs-SiO{sub 2} composite shows a very bright blue fluorescence visible by naked eyes for few seconds indicating their promise for display applications.

  19. Defect-free ZnO nanorods for low temperature hydrogen sensor applications

    SciTech Connect (OSTI)

    Ranwa, Sapana; Kumar, Mahesh; Kulriya, Pawan K.; Sahu, Vikas Kumar; Kukreja, L. M.

    2014-11-24

    Uniformly distributed and defect-free vertically aligned ZnO nanorods (NRs) with high aspect ratio are deposited on Si by sputtering technique. X-ray diffraction along with transmission electron microscopy studies confirmed the single crystalline wurtzite structure of ZnO. Absence of wide band emission in photoluminescence spectra showed defect-free growth of ZnO NRs which was further conformed by diamagnetic behavior of the NRs. H{sub 2} sensing mechanism based on the change in physical dimension of channel is proposed to explain the fast response (?21.6?s) and recovery times (?27?s) of ZnO NRs/Si/ZnO NRs sensors. Proposed H{sub 2} sensor operates at low temperature (?70?C) unlike the existing high temperature (>150?C) sensors.

  20. Manipulation of exciton and photon lasing in a membrane-type ZnO microcavity

    SciTech Connect (OSTI)

    Lai, Ying-Yu; Chen, Jee-Wei; Chang, Tsu-Chi; Lu, Tien-Chang; Chou, Yu-Hsun

    2015-03-30

    We report on the fabrication and characterization of a membrane-type ZnO microcavity (MC). The ZnO membrane was cut from a single crystalline ZnO substrate by using focused ion beam milling, and was then placed onto a SiO{sub 2} substrate by using glass microtweezers. Through changing the pumping regime, manipulation of P-band exciton lasing and whispering-gallery mode (WGM) photon lasing could be easily achieved. P-band exciton lasing was observed only when the pumping laser was focused at the center of the ZnO MC with a small pumping size because of the innate ring-shaped WGM distribution. Furthermore, the lasing threshold of the ZnO MC could be reduced to an order lower by using a larger pumping spot because of the more favorable spatial overlap between the optical gain and WGM.

  1. Purification of CdZnTe by Electromigration

    SciTech Connect (OSTI)

    Kim, K.; Kim, Sangsu; Hong, Jinki; Lee, Jinseo; Hong, Taekwon; Bolotnikov, A. E.; Camarda, G. S.; James, R. B.

    2015-04-14

    Electro-migration of ionized/electrically active impurities in CdZnTe (CZT) was successfully demonstrated at elevated temperature with an electric field of 20 V/mm. Copper, which exists in positively charged states, electro-migrated at a speed of 15 lm/h in an electric field of 20 V/mm. A notable variation in impurity concentration along the growth direction with the segregation tendency of the impurities was observed in an electro-migrated CZT boule. Notably, both Ga and Fe, which exist in positively charged states, exhibited the opposite distribution to that of their segregation tendency in Cd(Zn)Te. Furthermore, a CZT detector fabricated from the middle portion of the electromigrated CZT boule showed an improved mobility-lifetime product of 0.91 10-2 cm2 /V, compared to that of 1.4 10-3 cm2 /V, observed in an as-grown (non-electro-migrated) CZT detector. The optimum radiation detector material would have minimum concentration of deep traps required for compensation.

  2. Purification of CdZnTe by Electromigration

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Kim, K.; Kim, Sangsu; Hong, Jinki; Lee, Jinseo; Hong, Taekwon; Bolotnikov, A. E.; Camarda, G. S.; James, R. B.

    2015-04-14

    Electro-migration of ionized/electrically active impurities in CdZnTe (CZT) was successfully demonstrated at elevated temperature with an electric field of 20 V/mm. Copper, which exists in positively charged states, electro-migrated at a speed of 15 lm/h in an electric field of 20 V/mm. A notable variation in impurity concentration along the growth direction with the segregation tendency of the impurities was observed in an electro-migrated CZT boule. Notably, both Ga and Fe, which exist in positively charged states, exhibited the opposite distribution to that of their segregation tendency in Cd(Zn)Te. Furthermore, a CZT detector fabricated from the middle portion of themore » electromigrated CZT boule showed an improved mobility-lifetime product of 0.91 10-2 cm2 /V, compared to that of 1.4 10-3 cm2 /V, observed in an as-grown (non-electro-migrated) CZT detector. The optimum radiation detector material would have minimum concentration of deep traps required for compensation.« less

  3. Structural Changes in Self-Catalyzed Adsorption of Carbon Monoxide on 1,4-Phenylene Diisocyanide Modified Au(111)

    SciTech Connect (OSTI)

    Kestell, John; Boscoboinik, J. Anibal; Cheng, Lanxia; Garvey, Michael; Bennett, Dennis W.; Tysoe, Wilfred T.

    2015-07-23

    The self-accelerated adsorption of CO on 1,4-phenylene diisocyanide (PDI)-derived oligomers on Au(111) is explored by reflectionabsorption infrared spectroscopy and scanning tunneling microscopy. PDI incorporates gold adatoms from the Au(111) surface to form one-dimensional (AuPDI)n chains that can also connect between gold nanoparticles on mica to form a conductive pathway between them. CO adsorption occurs in two stages; it first adsorbs adjacent to the oligomers that move to optimize CO adsorption. Further CO exposure induces PDI decoordination to form AuPDI adatom complexes thereby causing the conductivity of a PDI-linked gold nanoparticle array on mica to decrease to act as a chemically drive molecular switch. This simple system enables the adsorption process to be explored in detail. DFT calculations reveal that both the (AuPDI)n oligomer chain and the AuPDI adatom complex are stabilized by coadsorbed CO. A kinetic foot-in-the-door model is proposed in which fluctuations in PDI coordination allow CO to diffuse into the gap between gold adatoms to prevent the PDI from reattaching, thereby allowing additional CO to adsorb, to provide kinetic model for allosteric CO adsorption on PDI-covered gold.

  4. Exchange bias effect in Au-Fe3O4 dumbbell nanoparticles induced by the charge transfer from gold

    SciTech Connect (OSTI)

    Feygenson, Mikhail; Bauer, John C.; Gai, Zheng; Marques, Carlos; Aronson, Meigan C.; Teng, Xiaowei; Su, Dong; Stanic, Vesna; Urban, Volker S.; Beyer, Kevin A.; Dai, Sheng

    2015-08-10

    We have studied the origin of the exchange bias effect in the Au-Fe3O4 dumbbell nanoparticles in two samples with different sizes of the Au seed nanoparticles (4.1 and 2.7 nm) and same size of Fe3O4 nanoparticles (9.8 nm). The magnetization, small-angle neutron-scattering, synchrotron x-ray diffraction, and scanning transmission electron microscope measurements determined the antiferromagnetic FeO wustite phase within Fe3O4 nanoparticles, originating at the interface with the Au nanoparticles. The interface between antiferromagnetic FeO and ferrimagnetic Fe3O4 is giving rise to the exchange bias effect. The strength of the exchange bias fields depends on the interfacial area and lattice mismatch between both phases. We propose that the charge transfer from the Au nanoparticles is responsible for a partial reduction of the Fe3O4 into the FeO phase at the interface with Au nanoparticles. The Au-O bonds are formed, presumably across the interface to accommodate an excess of oxygen released during the reduction of magnetite

  5. Exchange bias effect in Au-Fe3O4 dumbbell nanoparticles induced by the charge transfer from gold

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Feygenson, Mikhail; Bauer, John C; Gai, Zheng; Marques, Carlos; Aronson, Meigan C.; Teng, Xiaowei; Su, Dong; Stanic, Vesna; Urban, Volker S; Kevin, Beyer; et al

    2015-08-10

    We have studied the origin of the exchange bias effect in the Au-Fe3O4 dumbbell nanoparticles in two samples with different sizes of the Au seed nanoparticles (4.1 and 2.7 nm) and same size of Fe3O4 nanoparticles (9.8 nm). The magnetization, small-angle neutron scattering, synchrotron x-ray diffraction and scanning transmission electron microscope measurements determined the antiferromagnetic FeO wüstite phase within Fe3O4 nanoparticles, originating at the interface with the Au nanoparticles. The interface between antiferromagnetic FeO and ferrimagnetic Fe3O4 is giving rise to the exchange bias effect. The strength of the exchange bias fields depends on the interfacial area and lattice mismatchmore » between both phases. We propose that the charge transfer from the Au nanoparticles is responsible for a partial reduction of the Fe3O4 into FeO phase at the interface with Au nanoparticles. The Au-O bonds are formed across the interface to accommodate an excess of oxygen released during the reduction of magnetite.« less

  6. Laser induced effects on ZnO targets upon ablation at 266 and 308 nm wavelengths

    SciTech Connect (OSTI)

    Jadraque, Maria; Martin, Margarita; Domingo, Concepcion

    2008-07-15

    The development of structural changes in ZnO targets, upon laser irradiation at the wavelengths of 266 and 308 nm, is studied by Raman spectroscopy. At the wavelength of 308 nm, oxygen vacancies are found to develop monotonically with increasing laser intensity. At 266 nm, a structural change in the irradiated ZnO targets, possibly related to nanostructuring, is observed above the laser fluence of 0.45 J cm{sup -2}. The different natures of the laser target interaction processes taking place at both wavelengths are investigated through the characterization of the composition and energy distribution of the species ejected in the ablation. The energy of the neutral Zn and Zn{sub 2} present in the ablation at 308 nm shows a smooth dependence on laser fluence which is consistent with the observed smooth development of oxygen vacancies. At 266 nm, the average kinetic energy of the ejected fragments is higher than at 308 nm and changes abruptly with the ablating laser fluence, consistently with the presence of a fluence threshold above which structural transform is observed at this wavelength. The plume shows the same neutral composition (Zn, ZnO, and Zn{sub 2}) at both wavelengths but the dependence on fluence of the ratio of neutral atomic Zn to the dimer Zn{sub 2} shows significant differences. From the latter, different temperature regimes can be inferred in the plume generated at both wavelengths. At 266 nm the cationic composition of the plume is mainly stoichiometric whereas at 308 nm ZnO{sub 2(3)}H{sub 2(1)}{sup +} cations have the highest intensity.

  7. Plasmonic excitations in ZnO/Ag/ZnO multilayer systems: Insight into interface and bulk electronic properties

    SciTech Connect (OSTI)

    Philipp, Martin; Knupfer, Martin; Buechner, Bernd; Gerardin, Hadia

    2011-03-15

    Electron energy-loss spectroscopy experiments in transmission were carried out on silver-based multi-layer systems, consisting of a silver layer of various thicknesses (8, 10 and 50 nm) sandwiched between two Al-doped ZnO layers. The films were produced by magnetron sputtering using potassium bromide single crystals as substrates. The electronic structure of these systems was probed and analyzed with respect to their plasmonic excitations, which can be basically split up into excitations of the electrons in the bulk silver and excitations at the ZnO:Al/Ag interface. A detailed examination of the momentum dependence of the plasmon peaks revealed a positive dispersion for both, the volume and the interface plasmon, where only for the first one a quadratic behavior (as expected for a free electron gas) could be observed. Furthermore, the peak width was analyzed and set into relation to electrical conductivity measurements by calculating the plasmon lifetime and the electron scattering rate. Here, a good agreement between these different methods was obtained.

  8. Structure, stability, and electronic property of carbon-doped gold clusters Au{sub n}C{sup ?} (n = 110): A density functional theory study

    SciTech Connect (OSTI)

    Yan, Li-Li; Liu, Yi-Rong; Huang, Teng; Jiang, Shuai; Wen, Hui; Gai, Yan-Bo; Zhang, Wei-Jun E-mail: wjzhang@aiofm.ac.cn; Huang, Wei E-mail: wjzhang@aiofm.ac.cn; School of Environmental Science and Optoelectronic Technology, University of Science and Technology of China, Hefei, Anhui 230026

    2013-12-28

    The equilibrium geometric structures, relative stabilities, and electronic properties of Au{sub n}C{sup ?} and Au{sub n+1}{sup ?} (n = 110) clusters are systematically investigated using density functional theory with hyper-generalized gradient approximation. The optimized geometries show that one Au atom capped on Au{sub n?1}C{sup ?} clusters is a dominant growth pattern for Au{sub n}C{sup ?} clusters. In contrast to Au{sub n+1}{sup ?} clusters, Au{sub n}C{sup ?} clusters are most stable in a quasi-planar or three-dimensional structure because C doping induces the local non-planarity while the rest of the structure continues to grow in a planar mode, resulting in an overall non-2D configuration. The relative stability calculations show that the impurity C atom can significantly enhance the thermodynamic stability of pure gold clusters. Moreover, the effect of C atom on the Au{sub n}{sup ?} host decreases with the increase of cluster size. The HOMO-LUMO gap curves show that the interaction of the C atom with Au{sub n}{sup ?} clusters improves the chemical stability of pure gold clusters, except for Au{sub 3}{sup ?} and Au{sub 4}{sup ?} clusters. In addition, a natural population analysis shows that the charges in corresponding Au{sub n}C{sup ?} clusters transfer from the Au{sub n}{sup ?} host to the C atom. Meanwhile, a natural electronic configuration analysis also shows that the charges mainly transfer between the 2s and 2p orbitals within the C atom.

  9. THE INNER COMA OF COMET C/2012 S1 (ISON) AT 0.53 AU AND 0.35 AU FROM THE SUN

    SciTech Connect (OSTI)

    Bonev, Boncho P.; Villanueva, Geronimo L.; Paganini, Lucas; DiSanti, Michal A.; Gibb, Erika L.; Mumma, Michael J.

    2014-11-20

    Using long-slit spectroscopy at the NASA Infrared Telescope Facility, we extracted H{sub 2}O production rates and spatial profiles of gas rotational temperature and molecular column abundance in comet C/2012 S1 ISON, observed at heliocentric distances of 0.53 and 0.35 AU. These measurements uniquely probed the physical environment in the inner collisional coma of this comet during its first (and last) approach to the Sun since being emplaced in the Oort Cloud some 4.5 billion years ago. Our observations revealed a comet evolving on various timescales, both over hours and days. At 0.35 AU, ISON showed a considerable decrease in water production rate in less than 2 hr, likely declining from a major outburst. Our measured temperature spatial distributions reflect the competition between the processes that cause heating and cooling in the coma, and also provide insight about the prevalent mechanism(s) of releasing gas-phase H{sub 2}O. The observed temperatures suggest that the comet was likely ejecting icy material continuously, which sublimated in the coma and heated the ambient gas, augmenting fast H-atoms produced by H{sub 2}O photolysis. ISON adds to the very limited sample of comets for which spatial-spectral studies of water temperatures have been conducted. These studies are now feasible and can be extended to comets having a variety of gas production rates. Continued synergy of such observations with both space missions like Rosetta and with physical models is strongly encouraged in order to gain a deeper understanding of the processes in the inner collisional zone of the cometary coma.

  10. Precise calibration of Mg concentration in Mg{sub x}Zn{sub 1-x}O thin films grown on ZnO substrates

    SciTech Connect (OSTI)

    Kozuka, Y.; Falson, J.; Tsukazaki, A.; Segawa, Y.; Makino, T.; Kawasaki, M.

    2012-08-15

    The growth techniques for Mg{sub x}Zn{sub 1-x}O thin films have advanced at a rapid pace in recent years, enabling the application of this material to a wide range of optical and electrical applications. In designing structures and optimizing device performances, it is crucial that the Mg content of the alloy be controllable and precisely determined. In this study, we have established laboratory-based methods to determine the Mg content of Mg{sub x}Zn{sub 1-x}O thin films grown on ZnO substrates, ranging from the solubility limit of x {approx} 0.4 to the dilute limit of x < 0.01. For the absolute determination of Mg content, Rutherford backscattering spectroscopy is used for the high Mg region above x = 0.14, while secondary ion mass spectroscopy is employed to quantify low Mg content. As a lab-based method to determine the Mg content, c-axis length is measured by x-ray diffraction and is well associated with Mg content. The interpolation enables the determination of Mg content to x = 0.023, where the peak from the ZnO substrate overlaps the Mg{sub x}Zn{sub 1-x}O peak in standard laboratory equipment, and thus limits quantitative determination. At dilute Mg contents below x = 0.023, the localized exciton peak energy of the Mg{sub x}Zn{sub 1-x}O films as measured by photoluminescence is found to show a linear Mg content dependence, which is well resolved from the free exciton peak of ZnO substrate down to x = 0.0043. Our results demonstrate that x-ray diffraction and photoluminescence in combination are appropriate methods to determine Mg content in a wide Mg range from x = 0.004 to 0.40 in a laboratory environment.

  11. Photoelectrochemical Stability and Alteration Products of n-Type Single-Crystal ZnO Photoanodes

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Paulauskas, I. E.; Jellison, G. E.; Boatner, L. A.; Brown, G. M.

    2011-01-01

    The photoelectrochemical stability and surface-alteration characteristics of doped and undoped n-type ZnO single-crystal photoanode electrodes were investigated. The single-crystal ZnO photoanode properties were analyzed using current-voltage measurements plus spectral and time-dependent quantum-yield methods. These measurements revealed a distinct anodic peak and an accompanying cathodic surface degradation process at negative potentials. The features of this peak depended on time and the NaOH concentration in the electrolyte, but were independent of the presence of electrode illumination. Current measurements performed at the peak indicate that charging and discharging effects are apparently taking place at the semiconductor/electrolyte interface. This result is consistent with themore » significant reactive degradation that takes place on the ZnO single crystal photoanode surface and that ultimately leads to the reduction of the ZnO surface to Zn metal. The resulting Zn-metal reaction products create unusual, dendrite-like, surface alteration structural features that were analyzed using x-ray diffraction, energy-dispersive analysis, and scanning electron microscopy. ZnO doping methods were found to be effective in increasing the n-type character of the crystals. Higher doping levels result in smaller depletion widths and lower quantum yields, since the minority carrier diffusion lengths are very short in these materials.« less

  12. Ethanol Steam Reforming on Co/CeO2: The Effect of ZnO Promoter

    SciTech Connect (OSTI)

    Davidson, Stephen; Sun, Junming; Wang, Yong

    2013-12-02

    A series of ZnO promoted Co/CeO2 catalysts were synthesized and characterized using XRD, TEM, H2-TPR, CO chemisorption, O2-TPO, IR-Py, and CO2-TPD. The effects of ZnO on the catalytic performances of Co/CeO2 were studied in ethanol steam reforming. It was found that the addition of ZnO facilitated the oxidation of Co0 via enhanced oxygen mobility of the CeO2 support which decreased the activity of Co/CeO2 in C–C bond cleavage of ethanol. 3 wt% ZnO promoted Co/CeO2 exhibited minimum CO and CH4 selectivity and maximum CO2 selectivity. This resulted from the combined effects of the following factors with increasing ZnO loading: (1) enhanced oxygen mobility of CeO2 facilitated the oxidation of CHx and CO to form CO2; (2) increased ZnO coverage on CeO2 surface reduced the interaction between CHx/CO and Co/CeO2; and (3) suppressed CO adsorption on Co0 reduced CO oxidation rate to form CO2. In addition, the addition of ZnO also modified the surface acidity and basicity of CeO2, which consequently affected the C2–C4 product distributions.

  13. Thermoelectric properties of rocksalt ZnO from first-principles calculations

    SciTech Connect (OSTI)

    Alvarado, Andrew; Attapattu, Jeevake; Zhang, Yi; Chen, Changfeng

    2015-10-28

    Zinc oxide (ZnO) undergoes a pressure-induced structural transition from its normal ambient-pressure wurtzite (WZ) phase to a rocksalt (RS) phase around 10 GPa. A recent experiment shows that the high-pressure RS ZnO phase can be recovered and stabilized at ambient conditions, which raises exciting prospects of expanding the range of properties of ZnO. For a fundamental understanding of the RS ZnO phase, we have performed first-principles calculations to determine its electronic, phonon, and thermodynamic properties at high (20 GPa) and ambient (0 GPa) pressure. Furthermore, we have calculated its electrical and thermal transport properties, which allow an evaluation of its thermoelectric figure of merit ZT at different temperature and doping levels. Our calculations show that the ambient-pressure RS ZnO phase can reach ZT values of 0.25 to 0.3 under both n-type and p-type doping in a large temperature range of 400 K to 800 K, which is considerably lower than the temperature range of 1400 K to 1600 K where WZ ZnO reaches similar ZT values. These results establish RS ZnO as a promising material for thermoelectric devices designed to operate at temperatures desirable for many heat recovery applications.

  14. ZnTeO{sub 3} crystal growth by a modified Bridgman technique

    SciTech Connect (OSTI)

    Nawash, Jalal M. Lynn, Kelvin G.

    2014-12-15

    Highlights: • ZnTeO{sub 3} single crystals were grown for the first time by a modified Bridgman method. • The growth is still possible in a system that lacks congruent melting. • A growth is best when melt is exposed to a steeper axial thermal gradient. • Optical and electrical properties were investigated for the grown crystals. - Abstract: Zinc Tellurite (ZnTeO{sub 3}) crystals were grown for the first time using a modified Bridgman method with a 2.5 kHz radio frequency (RF) furnace. Single crystal growth of ZnTeO{sub 3} was hindered by many complicating factors, such as the evaporation of TeO{sub 2} above 700 °C and the formation of more than one phase during crystal growth. While there were several successful runs that produced ZnTeO{sub 3} single crystals, it was found that large (≥10 cm{sup 3}) single ZnTeO{sub 3} crystals resulted when the crucible was exposed to a steeper vertical thermal gradient and when the temperature of the melt was raised to at least 860 °C. The results of powder X-ray diffraction (XRD) patterns were in accordance with the X-ray powder diffraction file (PDF) for ZnTeO{sub 3}. Some optical, electrical and structural properties of ZnTeO{sub 3} single crystals were reported in this paper.

  15. High electron mobility ZnO film for high-performance inverted polymer solar cells

    SciTech Connect (OSTI)

    Lv, Peiwen; Chen, Shan-Ci; Zheng, Qingdong; Huang, Feng Ding, Kai

    2015-04-20

    High-quality ZnO films (ZnO-MS) are prepared via magnetron sputtering deposition with a high mobility of about 2 cm{sup 2}/(V·s) and are used as electron transport layer for inverted polymer solar cells (PSCs) with polymer poly[4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)benzo[1,2-b:4,5-b′] dithiophene-co-3-fluorothieno[3,4-b]thiophene-2-carboxylate]:[6,6]-phenyl C71-butyric acid methyl ester as the active layer. A significant improvement of J{sub SC}, about 20% enhancement in contrast to the devices built on sol-gel derived ZnO film (ZnO-Sol), is found in the ZnO-MS based device. High performance ZnO-MS based PSCs exhibit power conversion efficiency (PCE) up to 8.55%, which is much better than the device based on ZnO-Sol (PCE = 7.78%). Further research on cathode materials is promising to achieve higher performance.

  16. Modifying structure-sensitive reactions by addition of Zn to Pd

    SciTech Connect (OSTI)

    Childers, David J.; Schweitzer, Neil M.; Kamali Shahari, Seyed Mehdi; Rioux, Robert M.; Miller, Jeffrey T.; Meyer, Randall J.

    2014-10-01

    Silica-supported Pd and PdZn nanoparticles of a similar size were evaluated for neopentane hydrogenolysis/isomerization and propane hydrogenolysis/dehydrogenation. Monometallic Pd showed high neopentane hydrogenolysis selectivity. Addition of small amounts of Zn to Pd lead Pd–Zn scatters in the EXAFS spectrum and an increase in the linear bonded CO by IR. In addition, the neopentane turnover rate decreased by nearly 10 times with little change in the selectivity. Increasing amounts of Zn lead to greater Pd–Zn interactions, higher linear-to-bridging CO ratios by IR and complete loss of neopentane conversion. Pd NPs also had high selectivity for propane hydrogenolysis and thus were poorly selective for propylene. The PdZn bimetallic catalysts, however, were able to preferentially catalyze dehydrogenation, were not active for propane hydrogenolysis, and thus were highly selective for propylene formation. The decrease in hydrogenolysis selectivity was attributed to the isolation of active Pd atoms by inactive metallic Zn,demonstrating that hydrogenolysis requires a particular reactive ensemble whereas propane dehydrogenation does not.

  17. Low temperature atomic layer deposited ZnO photo thin film transistors

    SciTech Connect (OSTI)

    Oruc, Feyza B.; Aygun, Levent E.; Donmez, Inci; Biyikli, Necmi; Okyay, Ali K.; Yu, Hyun Yong

    2015-01-01

    ZnO thin film transistors (TFTs) are fabricated on Si substrates using atomic layer deposition technique. The growth temperature of ZnO channel layers are selected as 80, 100, 120, 130, and 250?C. Material characteristics of ZnO films are examined using x-ray photoelectron spectroscopy and x-ray diffraction methods. Stoichiometry analyses showed that the amount of both oxygen vacancies and interstitial zinc decrease with decreasing growth temperature. Electrical characteristics improve with decreasing growth temperature. Best results are obtained with ZnO channels deposited at 80?C; I{sub on}/I{sub off} ratio is extracted as 7.8 10{sup 9} and subthreshold slope is extracted as 0.116 V/dec. Flexible ZnO TFT devices are also fabricated using films grown at 80?C. I{sub D}V{sub GS} characterization results showed that devices fabricated on different substrates (Si and polyethylene terephthalate) show similar electrical characteristics. Sub-bandgap photo sensing properties of ZnO based TFTs are investigated; it is shown that visible light absorption of ZnO based TFTs can be actively controlled by external gate bias.

  18. Characterization of one-dimensional molecular chains of 4,4'-biphenyl diisocyanide on Au(111) by scanning tunneling microscopy

    SciTech Connect (OSTI)

    Zhou, Jing; Li, Yan; Zahl, Percy; Sutter, Peter; Stacchiola, Dario J.; White, Michael G.

    2015-03-14

    The morphology and electronic structure of vapor deposited 4,4'-biphenyldiisocyanide (BPDI) on a Au(111) surface were investigated using variable-temperature scanning tunneling microscopy (STM). When deposited at room temperature, BPDI molecules form one-dimensional molecular chains similar to that recently observed for the structurally related 1,4-phenyl diisocyanide (PDI). Compared to PDI, the longer periodicity for the BPDI molecular chains is consistent with the addition of a second phenyl ring and supports a structural model in which the BPDI molecules lie parallel to the surface and interconnected by Au-adatoms. The molecular chains are mostly aligned along the [110] direction of the Au(111) substrate, but exhibit frequent changes in angle that are consistent with directions between fcc and hcp three-fold hollow sites. Dispersion-corrected density functional theory calculations for one-dimensional chains of BPDI molecules bound end-to-end via their isocyanide groups to Au-adatoms reproduce the observed periodicity of the chains and show that this morphology is energetically favored over upright binding with one free –NC group. The spatially resolved conductance (dI/dV) map for BPDI on Au(111) exhibits a feature centered at -0.67 eV below the Fermi level which are delocalized along the chain with maxima at the Au-adatom and biphenyl positions. This occupied resonant feature is close to that previously observed for the PDI in both photoemission and conductance measurements and is attributed to an occupied interfacial state resulting from BPDI-Au interactions

  19. Characterization of one-dimensional molecular chains of 4,4'-biphenyl diisocyanide on Au(111) by scanning tunneling microscopy

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Zhou, Jing; Li, Yan; Zahl, Percy; Sutter, Peter; Stacchiola, Dario J.; White, Michael G.

    2015-03-14

    The morphology and electronic structure of vapor deposited 4,4'-biphenyldiisocyanide (BPDI) on a Au(111) surface were investigated using variable-temperature scanning tunneling microscopy (STM). When deposited at room temperature, BPDI molecules form one-dimensional molecular chains similar to that recently observed for the structurally related 1,4-phenyl diisocyanide (PDI). Compared to PDI, the longer periodicity for the BPDI molecular chains is consistent with the addition of a second phenyl ring and supports a structural model in which the BPDI molecules lie parallel to the surface and interconnected by Au-adatoms. The molecular chains are mostly aligned along the [110] direction of the Au(111) substrate, butmore » exhibit frequent changes in angle that are consistent with directions between fcc and hcp three-fold hollow sites. Dispersion-corrected density functional theory calculations for one-dimensional chains of BPDI molecules bound end-to-end via their isocyanide groups to Au-adatoms reproduce the observed periodicity of the chains and show that this morphology is energetically favored over upright binding with one free –NC group. The spatially resolved conductance (dI/dV) map for BPDI on Au(111) exhibits a feature centered at -0.67 eV below the Fermi level which are delocalized along the chain with maxima at the Au-adatom and biphenyl positions. This occupied resonant feature is close to that previously observed for the PDI in both photoemission and conductance measurements and is attributed to an occupied interfacial state resulting from BPDI-Au interactions« less

  20. Performance evaluation of ZnO–CuO hetero junction solid state room temperature ethanol sensor

    SciTech Connect (OSTI)

    Yu, Ming-Ru; Suyambrakasam, Gobalakrishnan; Wu, Ren-Jang; Department of Nanotechnology, School of Interdisciplinary Courses, Noorul Islam Centre for Higher Education, Noorul Islam University, Kumaracoil 629180, Tamil Nadu ; Chavali, Murthy; Department of Applied Chemistry, Providence University, 200 Chungchi Road, Shalu, Taichung Hsien 433, Taiwan, R.O.C

    2012-07-15

    Graphical abstract: Sensor response (resistance) curves of time were changed from 150 ppm to 250 ppm alcohol concentration of ZnO–CuO 1:1. The response and recovery times were measured to be 62 and 83 s, respectively. The sensing material ZnO–CuO is a high potential alcohol sensor which provides a simple, rapid and highly sensitive alcohol gas sensor operating at room temperature. Highlights: ► The main advantages of the ethanol sensor are as followings. ► Novel materials ZnO–CuO ethanol sensor. ► The optimized ZnO–CuO hetero contact system. ► A good sensor response and room working temperature (save energy). -- Abstract: A semiconductor ethanol sensor was developed using ZnO–CuO and its performance was evaluated at room temperature. Hetero-junction sensor was made of ZnO–CuO nanoparticles for sensing alcohol at room temperature. Nanoparticles were prepared by hydrothermal method and optimized with different weight ratios. Sensor characteristics were linear for the concentration range of 150–250 ppm. Composite materials of ZnO–CuO were characterized using X-ray diffraction (XRD), temperature-programmed reduction (TPR) and high-resolution transmission electron microscopy (HR-TEM). ZnO–CuO (1:1) material showed maximum sensor response (S = R{sub air}/R{sub alcohol}) of 3.32 ± 0.1 toward 200 ppm of alcohol vapor at room temperature. The response and recovery times were measured to be 62 and 83 s, respectively. The linearity R{sup 2} of the sensor response was 0.9026. The sensing materials ZnO–CuO (1:1) provide a simple, rapid and highly sensitive alcohol gas sensor operating at room temperature.

  1. Synthesis of Sn-doped ZnO nanorods and their photocatalytic properties

    SciTech Connect (OSTI)

    Wu, Changle; Shen, Li; Yu, Huaguang; Huang, Qingli; Zhang, Yong Cai

    2011-07-15

    Graphical abstract: Sn-doped ZnO nanorods have been fabricated by a hydrothermal route. Photocatalytic activity of the Sn-doped ZnO samples increases gradually with an increase of the Sn content. Highlights: {yields} Sn-doped ZnO nanorods were fabricated by a hydrothermal route. {yields} Solid-state NMR result confirms Sn{sup 4+} was incorporated into the lattice of ZnO. {yields} The visible luminescence intensity increased with increase in Sn concentration. {yields} Photocatalytic activity of Sn-doped ZnO increases with increasing Sn content. -- Abstract: Sn-doped ZnO nanorods were fabricated by a hydrothermal route, and characterized by X-ray diffraction, field emission scanning electron microscope, UV-vis spectroscopy, Raman spectra, solid-state nuclear magnetic resonance (NMR) spectra, and room temperature photoluminescence spectroscopy. Solid-state NMR result confirms that Sn{sup 4+} was successfully incorporated into the crystal lattice of ZnO. Room temperature photoluminescence showed that all the as-synthesized products exhibited a weak UV emission (380 nm) and a strong visible emission (540 nm), but the intensities of the latter emission increased with increase in Sn concentration. The improvement of visible emission at 540 nm in the Sn-doped ZnO samples was suggested to be a result of the lattice defects increased by doping of Sn in zinc oxide. In addition, the photocatalytic studies indicated that Sn-doped ZnO nanorods are a kind of promising photocatalyst in remediation of water polluted by some chemically stable azo dyes.

  2. Top-emission Si-based phosphor organic light emitting diode with Au doped ultrathin n-Si film anode and bottom Al mirror

    SciTech Connect (OSTI)

    Li, Y. Z.; Xu, W. J.; Ran, G. Z. [State Key Laboratory for Mesoscopic Physics, School of Physics, Peking University, Beijing 100871 (China); Qin, G. G. [State Key Laboratory for Mesoscopic Physics, School of Physics, Peking University, Beijing 100871 (China); Key Lab of Semiconductor Materials, CAS, Beijing 100083 (China)

    2009-07-20

    We report a highly efficient top-emission Si-based phosphor organic light emitting diode (PhOLED) with an ultrathin polycrystalline n-Si:Au film anode and a bottom Al mirror. This anode is formed by magnetron sputtering followed by Ni induced crystallization and then Au diffusion. By optimizing the thickness of the n-Si:Au film anode, the Au diffusion temperature, and the other parameters of the PhOLED, the highest current and power efficiencies of the n-Si:Au film anode PhOLED reached 85{+-}9 cd/A and 80{+-}8 lm/W, respectively, corresponding to an external quantum efficiency of 21{+-}2% and a power conversion efficiency of 15{+-}2%, respectively, which are about 60% and 110% higher than those of the indium tin oxide anode counterpart and 70% and 50% higher than those of the bulk n{sup +}-Si:Au anode counterpart, respectively.

  3. Polarity effects in the x-ray photoemission of ZnO and other wurtzite semiconductors

    SciTech Connect (OSTI)

    Allen, M. W.; Zemlyanov, D. Y.; Waterhouse, G. I. N.; Metson, J. B.; Veal, T. D.; McConville, C. F.; Durbin, S. M.

    2011-03-07

    Significant polarity-related effects were observed in the near-surface atomic composition and valence band electronic structure of ZnO single crystals, investigated by x-ray photoemission spectroscopy using both Al K{sub {alpha}} (1486.6 eV) and synchrotron radiation (150 to 1486 eV). In particular, photoemission from the lowest binding energy valence band states was found to be significantly more intense on the Zn-polar face compared to the O-polar face. This is a consistent effect that can be used as a simple, nondestructive indicator of crystallographic polarity in ZnO and other wurtzite semiconductors.

  4. Phosphorescence quenching by mechanical stimulus in CaZnOS:Cu

    SciTech Connect (OSTI)

    Tu, Dong; Kamimura, Sunao; Xu, Chao-Nan; Fujio, Yuki; Sakata, Yoshitaro; Ueno, Naohiro

    2014-07-07

    We have found that phosphorescence intensity of CaZnOS:Cu decreased visibly under an applied load. This mechanical quenching (MQ) of phosphorescence in CaZnOS:Cu corresponded to the mechanical stimuli. We have thus demonstrated that the MQ of CaZnOS:Cu could be used for visualizing stress distributions in practical applications. We propose that MQ arises from non-radiative recombination due to electron-transfer from trap levels to non-radiative centers as a result of the mechanical load.

  5. ZnO/porous-Si and TiO{sub 2}/porous-Si nanocomposite nanopillars

    SciTech Connect (OSTI)

    Wang, Dong, E-mail: dong.wang@tu-ilmenau.de; Yan, Yong; Schaaf, Peter [Chair Materials for Electronics, Institute of Materials Engineering and Institute of Micro- and Nanotechnologies MacroNano, TU Ilmenau, Gustav-Kirchhoff-Str. 5, 98693 Ilmenau (Germany); Sharp, Thomas [Oxford Instruments Plasma Technology Ltd., Yatton, Bristol BS49 4AP (United Kingdom); Schnherr, Sven; Ronning, Carsten [Institute for Solid State Physics, Friedrich Schiller University Jena, Max-Wien-Platz 1, 07743 Jena (Germany); Ji, Ran [SUSS MicroTec Lithography GmbH, Schleissheimer Str. 90, 85748 Garching (Germany)

    2015-01-01

    Porous Si nanopillar arrays are used as templates for atomic layer deposition of ZnO and TiO{sub 2}, and thus, ZnO/porous-Si and TiO{sub 2}/porous-Si nanocomposite nanopillars are fabricated. The diffusion of the precursor molecules into the inside of the porous structure occurs via Knudsen diffusion and is strongly limited by the small pore size. The luminescence of the ZnO/porous-Si nanocomposite nanopillars is also investigated, and the optical emission can be changed and even quenched after a strong plasma treatment. Such nanocomposite nanopillars are interesting for photocatalysis and sensors.

  6. H2S removal with ZnO during fuel processing for PEM fuel cell applications

    SciTech Connect (OSTI)

    Li, Liyu; King, David L.

    2006-09-15

    The possibility of using ZnO as a H2S absorbent to protect catalysts in the gasoline and diesel fuel processor for PEM fuel cell applications was studied. It is possible to use commercial ZnO absorbent as a guard bed to protect the PROX catalyst and PEM fuel cell. However, it is not feasible to use ZnO to protect high and low temperature WGS catalysts, most likely due to COS formation via reactions CO + H2S = COS + H2 and CO2 + H2S = COS + H2O.

  7. Magnetism of Co doped ZnO with Al codoping: carrier induced mechanisms versus extrinsic origins

    SciTech Connect (OSTI)

    Ney, A.; Ney, V.; Ye, S.; Ollefs, K.; Kammermeier, T.; Kaspar, Tiffany C.; Chambers, Scott A.; Wilhelm, F.; Rogalev, A.

    2010-07-23

    Dilute magnetic semiconductors (DMS) which exhibit ferromagnetism (FM) at and above room temperature are a highly desirable class of materials for future spin- tronics devices. Zn1?xCoxO (Co:ZnO) is a heavily studied DMS material in this context. Although controversially discussed in the literature, there is a growing con- sensus, that phase-pure Co:ZnO is paramagnetic (PM)[13]. Altering the preparation conditions can easily lead to phase separation and consequently superparam- agnetism (SPM) [3]. Nonetheless there are recent experimental data claiming that FM can be switched on inCo:ZnO by controlling the carrier concentration [4]. On the other hand, no FM was found in structurally excellent Al-codoped Co:ZnO [5]. However, in the latter work the magnetic characterization was restricted to room temperature measurements. In parallel, theory has also revealed that defect-free, insulating Co:ZnO is not ferromagnetic [6, 7] whereas the role of n-type carriers remains under debate, ranging from ferromagnetic coupling [8], or oscil- latory behavior with Co-Co distance [9] to antiferromagnetic coupling [10]. It is rather common to manipulate the n-type carrier concentration of ZnO by Al-doping to yield high conductivity [4, 11]. On the other hand, it had been shown that Al-codoping of Co:ZnO may promote the onset of phase separation [11]. It is extremely difficult to detect such secondary Co-containing phases even with the most careful x-ray diffraction (XRD) analysis [11, 12] or depth-profiling photoelectron spectroscopy (DP-XPS) [13]. Such careful materials characterization is lacking in Ref. [4]. An alternative to extensive XRD or DP-XPS to look for potential phase separation in Co:ZnO is the combination of x-ray absorption near edge spectra (XANES), x-ray linear dichroism (XLD), and x-ray magnetic circular dichroism (XMCD). This suite of atom-specific x-ray spectroscopies nicely complements integral superconducting quantum interference device (SQUID) magnetometry

  8. Ni, Fe Co-doped ZnO nanoparticles synthesized by solution combustion method

    SciTech Connect (OSTI)

    Dhiman, Pooja Chand, Jagdish Verma, S. Sarveena, Singh, M.

    2014-04-24

    This paper outlines the synthesis and characterization of Ni-Fe co-doped ZnO nanoparticles by facile solution combustion method. The structural characterization by XRD confirmed the phase purity of the samples. Surface morphology studied by scanning electron microscope revealed cubic type shape of grains. EDS analysis conformed the elemental composition. Higher value of DC electrical conductivity and less band gap for co-doped ZnO from UV-Vis studies confirmed the change in defect chemistry of ZnO Matrix.

  9. Synthesis and characterization of ZnO nanostructured film for optoelectronic applications

    SciTech Connect (OSTI)

    Kumar, Vijay E-mail: sanjeev04101977@gmail.com; Singh, Harpreetpal

    2015-05-15

    ZnO nanostructured film is synthesized by solution combustion technique. X-ray diffraction (XRD) studies show that preferred orientation is along (101) confirming the hexagonal wurtzite phase and no secondary phase is observed. The rietveld refinement of the XRD data was used to calculate different lattice parameters. I-V characterization of ZnO film shows non linear behavior. These ZnO films are photosensitive, may be due to defect states. This property of these films can be utilized in optoelectronic applications.

  10. Structural studies and band gap tuning of Cr doped ZnO nanoparticles

    SciTech Connect (OSTI)

    Srinet, Gunjan Kumar, Ravindra Sajal, Vivek

    2014-04-24

    Structural and optical properties of Cr doped ZnO nanoparticles prepared by the thermal decomposition method are presented. X-ray diffraction studies confirmed the substitution of Cr on Zn sites without changing the wurtzite structure of ZnO. Modified form of W-H equations was used to calculate various physical parameters and their variation with Cr doping is discussed. Significant red shift was observed in band gap, i.e., a band gap tuning is achieved by Cr doping which could eventually be useful for optoelectronic applications.

  11. INTERMEDIATE-MASS HOT CORES AT {approx}500 AU: DISKS OR OUTFLOWS?

    SciTech Connect (OSTI)

    Palau, Aina; Girart, Josep M.; Fuente, Asuncion; Alonso-Albi, Tomas; Fontani, Francesco; Sanchez-Monge, Alvaro; Boissier, Jeremie; Pietu, Vincent; Neri, Roberto; Busquet, Gemma; Estalella, Robert; Zapata, Luis A.; Zhang, Qizhou; Ho, Paul T. P.; Audard, Marc

    2011-12-20

    Observations with the Plateau de Bure Interferometer in the most extended configuration toward two intermediate-mass star-forming regions, IRAS 22198+6336 and AFGL 5142, reveal the presence of several complex organic molecules at {approx}500 AU scales, confirming the presence of hot cores in both regions. The hot cores are not rich in CN-bearing molecules, as often seen in massive hot cores, and are mainly traced by CH{sub 3}CH{sub 2}OH, (CH{sub 2}OH){sub 2}, CH{sub 3}COCH{sub 3}, and CH{sub 3}OH, with, additionally, CH{sub 3}CHO, CH{sub 3}OD, and HCOOD for IRAS 22198+6336, and C{sub 6}H and O{sup 13}CS for AFGL 5142. The emission of complex molecules is resolved down to sizes of {approx}300 and {approx}600 AU, for IRAS 22198+6336 and AFGL 5142, respectively, and most likely is tracing protostellar disks rather than flattened envelopes or toroids as is usually found. This is especially clear for the case of IRAS 22198+6336, where we detect a velocity gradient for all the mapped molecules perpendicular to the most chemically rich outflow of the region, yielding a dynamic mass {approx}> 4 M{sub Sun }. As for AFGL 5142, the hot core emission is resolved into two elongated cores separated {approx}1800 AU. A detailed comparison of the complex molecule peaks to the new CO (2-1) data and H{sub 2}O maser data from the literature suggests also that for AFGL 5142 the complex molecules are mainly associated with disks, except for a faint and extended molecular emission found to the west, which is possibly produced in the interface between one of the outflows and the dense surrounding gas.

  12. EXPLORING INTERMEDIATE (5-40 AU) SCALES AROUND AB AURIGAE WITH THE PALOMAR FIBER NULLER

    SciTech Connect (OSTI)

    Kühn, J.; Mennesson, B.; Liewer, K.; Martin, S.; Loya, F.; Serabyn, E.; Millan-gabet, R.

    2015-02-10

    We report on recent K{sub s} -band interferometric observations of the young pre-main-sequence star AB Aurigae obtained with the Palomar Fiber Nuller (PFN). Reaching a contrast of a few 10{sup –4} inside a field of view extending from 35 to 275 mas (5-40 AU at AB Aur's distance), the PFN is able to explore angular scales that are intermediate between those accessed by coronagraphic imaging and long baseline interferometry. This intermediate region is of special interest given that many young stellar objects are believed to harbor extended halos at such angular scales. Using destructive interference (nulling) between two sub-apertures of the Palomar 200 inch telescope and rotating the telescope pupil, we measured a resolved circumstellar excess at all probed azimuth angles. The astrophysical null measured over the full rotation is fairly constant, with a mean value of 1.52%, and a slight additional azimuthal modulation of ±0.2%. The isotropic astrophysical null is indicative of circumstellar emission dominated by an azimuthally extended source, possibly a halo, or one or more rings of dust, accounting for several percent of the total K{sub s}-band flux. The modest azimuthal variation may be explained by some skewness or anisotropy of the spatially extended source, e.g., an elliptical or spiral geometry, or clumping, but it could also be due to the presence of a point source located at a separation of ∼120 mas (17 AU) with ∼6 × 10{sup –3} of the stellar flux. We combine our results with previous Infrared Optical Telescope Array observations of AB Aur at H band, and demonstrate that a dust ring located at ∼30 mas (4.3 AU) represents the best-fitting model to explain both sets of visibilities. We are also able to test a few previously hypothesized models of the incoherent component evident at longer interferometric baselines.

  13. The Correlation of Stress-State and Nano-Mechanical Properties in Au

    SciTech Connect (OSTI)

    HOUSTON,JACK E.; JARAUSCH,K.F.; KIELY,J.D.; RUSSELL,P.E.

    1999-10-07

    A dependence of elastic response on the stress-state of a thin film has been demonstrated using the interfacial force microscope (IFM). Indentation response was measured as a function of the applied biaxial stress-state for 100 nm thick Au films. An increase in measured elastic modulus with applied compressive stress, and a decrease with applied tensile stress was observed. Measurements of elastic modulus before and after applying stress were identical indicating that the observed change in response is not due to a permanent change in film properties.

  14. AU Funtional Area Points of Contact by Office Directors - July 7, 2016

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Functional Area Points of Contact Listing by AU Office Director 1 Function/Subject Director Email Phone Accident Investigations Josh Silverman Josh.Silverman@hq.doe.gov (202) 586-6535 Administrative Review (Clearance eligibility determinations) Sam Callahan Samuel.Callahan@hq.doe.gov (301) 903-3767 Annual Report to Congress on Special Nuclear Material Robert Lingan Robert.lingan@hq.doe.gov (202) 586-1461 Annual Site Environmental Reports Josh Silverman Josh.Silverman@hq.doe.gov (202) 586-6535

  15. Coulomb Excitation of Neutron-Rich Zn Isotopes: First Observation of the 2{sub 1}{sup +} State in {sup 80}Zn

    SciTech Connect (OSTI)

    Van de Walle, J.; Cocolios, T. E.; Huyse, M.; Ivanov, O.; Mayet, P.; Raabe, R.; Sawicka, M.; Stefanescu, I.; Duppen, P. van; Aksouh, F.; Behrens, T.; Gernhauser, R.; Kroell, T.; Kruecken, R.; Bildstein, V.; Blazhev, A.; Eberth, J.

    2007-10-05

    Neutron-rich, radioactive Zn isotopes were investigated at the Radioactive Ion Beam facility REX-ISOLDE (CERN) using low-energy Coulomb excitation. The energy of the 2{sub 1}{sup +} state in {sup 78}Zn could be firmly established and for the first time the 2{sup +}{yields}0{sub 1}{sup +} transition in {sup 80}Zn was observed at 1492(1) keV. B(E2,2{sub 1}{sup +}{yields}0{sub 1}{sup +}) values were extracted for {sup 74,76,78,80}Zn and compared to large scale shell model calculations. With only two protons outside the Z=28 proton core, {sup 80}Zn is the lightest N=50 isotone for which spectroscopic information has been obtained to date. Two sets of advanced shell model calculations reproduce the observed B(E2) systematics. The results for N=50 isotones indicate a good N=50 shell closure and a strong Z=28 proton core polarization. The new results serve as benchmarks to establish theoretical models, predicting the nuclear properties of the doubly magic nucleus {sup 78}Ni.

  16. X-ray absorption studies of mixed salt polymer electrolytes: ZnBr{sub 2}/CaBr{sub 2}-PEO, ZnBr{sub 2}/LiBr-PEO, and ZnBr{sub 2}/RbBr-PEO complexes

    SciTech Connect (OSTI)

    McBreen, J.; Yang, X.Q.; Lee, H.S.; Okamoto, Y.

    1995-02-01

    Polyethylene oxide (PEO)-salt systems are an important new class of electrolytes that are being considered for many uses. X-ray absorption (XAS) studies of ZnBr{sub 2}-PEO complexes, at the Zn K edge, at temperatures between 25 and 120 C, indicate that additions of bromide salts of Li, Rb, or Ca result in the formation of ZnBr{sub 4}{sup {minus} 2} complexes with a Zn-Br bond length of 2.42 {angstrom}. XAS, at the Rb K edge, in mixed RbBr/ZnBr{sub 2}-PEO complexes with an excess of ZnBr{sub 2}, shows that the ZnBr{sub 2} causes the RbBr to dissolve in the polymer. The Rb{sup +} ions are weakly complexed with the PEO with an Rb-O bond distance of 2.93 {angstrom}.

  17. Phase relations and structural features in the system Ni-Zn-B

    SciTech Connect (OSTI)

    Malik, Z.; Grytsiv, A.; Rogl, P.; Giester, G.; Bursik, J.

    2013-02-15

    Phase relations for the system Ni-Zn-B have been established in the isothermal section at 800 Degree-Sign C based on X-ray powder diffraction and electron microprobe analyses of about 60 samples, which have been prepared by hot pressing of pre-annealed powder compacts of arc-melted master alloys Ni{sub x}B{sub y} and Zn-filings. Six ternary compounds (labeled {tau}{sub 1} to {tau}{sub 6}) were found to exist, which in some cases exhibit considerable mutual solid solubilities mostly as an exchange of Ni-Zn at constant B-content, but in the case of the so-called {tau}-phase {tau}{sub 1}-(Ni{sub 1-x}Zn{sub x}){sub 21}[Zn{sub 1-y-z}{open_square}{sub y}(B{sub 4}){sub z}]{sub 2}B{sub 6} (0.07{<=}x{<=}0.11, 0.07{<=}y{<=}0.53, 0{<=}z{<=}0.3) also with Zn/B substitution. Single crystal X-ray data analysis for the composition x=0.07, y=0.125, z=0.30, and a=1.05800(3) nm confirmed the Cr{sub 23}C{sub 6} type with space group Fm3{sup Macron }m, but revealed partial replacement of Zn-atoms by B{sub 4}-tetrahedra (R{sub F}=0.014). Whereas Ni/Zn exchange (at constant B-content) ranges at about 4-5 at% for {tau}{sub 4}-Ni{sub 3}ZnB{sub 2} and {tau}{sub 5}-Ni{sub 48}Zn{sub 32}B{sub 20}, it is below 3 at% for {tau}{sub 2}-Ni{sub 12}ZnB{sub 8-x} (x=0.43), {tau}{sub 3}-Ni{sub 21}Zn{sub 2}B{sub 20} and {tau}{sub 6}-Ni{sub 47}Zn{sub 23}B{sub 30}. The crystal structures of {tau}{sub 2}-Ni{sub 12}ZnB{sub 8-x} (x=0.43; Ni{sub 12}AlB{sub 8} type), {tau}{sub 3}-Ni{sub 21}Zn{sub 2}B{sub 20} (own type) and {tau}{sub 4}-Ni{sub 3}ZnB{sub 2} (own type) have been determined in our foregoing paper [8]. Due to the non-availability of suitable single crystals, the crystal structures of {tau}{sub 5}-Ni{sub 48}Zn{sub 32}B{sub 20} (body-centered orthorhombic; a=1.6(2) nm, b=0.63(7) nm, and c=0.27(0) nm, determined from TEM) and of {tau}{sub 6}-Ni{sub 47}Zn{sub 23}B{sub 30} have not been elucidated yet. Phase equilibria at 800 Degree-Sign C are dominated by a large three-phase field ({beta}B)+Ni{sub 2}Zn

  18. Angular distribution and recoil effect for 1 MeV Au+ ions through a Si3N4 thin foil

    SciTech Connect (OSTI)

    Jin, Ke; Zhu, Zihua; Manandhar, Sandeep; Liu, Jia; Chen, Chien-Hung; Shutthanandan, Vaithiyalingam; Thevuthasan, Suntharampillai; Weber, William J; Zhang, Yanwen

    2014-01-01

    The Stopping and Range of Ions in Matter (SRIM) code has been widely used to predict nuclear stopping power and angular distribution of ion-solid collisions. However, experimental validation of the predictions is insufficient for slow heavy ions in nonmetallic compounds. In this work, time-of-flight secondary ion mass spectrometry (ToF-SIMS) is applied to determine the angular distribution of 1 MeV Au ions after penetrating a Si3N4 foil with a thickness of ~100 nm. The exiting Au ions are collected by a Si wafer located ~14 mm behind the Si3N4 foil, and the resulting 2-dimensional distribution of Au ions on the Si wafer is measured by ToF-SIMS. The SRIM-predicted angular distribution of Au ions through the Si3N4 thin foil is compared with the measured results, indicating that SRIM slightly overestimates the nuclear stopping power by up to 10%. In addition, thickness reduction of the suspended Si3N4 foils induced by 1 MeV Au ion irradiation is observed with an average loss rate of ~107 atom/ion.

  19. Tailoring characteristic thermal stability of Ni-Au binary nanocrystals via structure and composition engineering: theoretical insights into structural evolution and atomic inter-diffusion

    SciTech Connect (OSTI)

    Li, Bangquan; Wang, Hailong; Xing, Guozhong; Wang, Rongming E-mail: rmwang@ustb.edu.cn

    2014-11-15

    We report on the structural evolution and atomic inter-diffusion characteristics of the bimetallic Ni-Au nanocrystals (NCs) by molecular dynamics simulations studies. Our results reveal that the thermal stability dynamics of Ni-Au NCs strongly depends on the atomic configurations. By engineering the structural construction with Ni:Au = 1:1 atomic composition, compared with core-shell Au@Ni and alloy NCs, the melting point of core-shell Ni@Au NCs is significantly enhanced up to 1215 K. Unexpectedly, with atomic ratio of Au:Ni= 1:9, the melting process initiates from the atoms in the shell of Ni@Au and alloy NCs, while starts from the core of Au@Ni NCs. The corresponding features and evolution process of structural motifs, mixing and segregation are illustrated via a series of dynamic simulations videos. Moreover, our results revealed that the face centered cubic phase Au{sub 0.75}Ni{sub 0.25} favorably stabilizes in NCs form but does not exist in the bulk counterpart, which elucidates the anomalies of previously reported experimental results on such bimetallic NCs.

  20. System size dependence of cluster properties from two-particle angular correlations in Cu+Cu and Au+Au collisions at sq root(s{sub NN})=200 GeV

    SciTech Connect (OSTI)

    Alver, B.; Ballintijn, M.; Busza, W.; Gulbrandsen, K.; Henderson, C.; Kane, J. L.; Kulinich, P.; Li, W.; Loizides, C.; Reed, C.; Roland, C.; Roland, G.; Stephans, G. S. F.; Nieuwenhuizen, G. J. van; Vaurynovich, S. S.; Verdier, R.; Veres, G. I.; Wenger, E.; Wyslouch, B.; Back, B. B.

    2010-02-15

    We present results on two-particle angular correlations in Cu+Cu and Au+Au collisions at a center-of-mass energy per nucleon pair of 200 GeV over a broad range of pseudorapidity (eta) and azimuthal angle (phi) values as a function of collision centrality. The PHOBOS detector at the Relativistic Heavy Ion Collider has a uniquely large angular coverage for inclusive charged particles, which allows for the study of correlations on both long- and short-range scales. A complex two-dimensional correlation structure in {Delta}{eta} and {Delta}{phi} emerges, which is interpreted in the context of a cluster model. The effective cluster size and decay width are extracted from the two-particle pseudorapidity correlation functions. The effective cluster size found in semicentral Cu+Cu and Au+Au collisions is comparable to that found in proton-proton collisions but a nontrivial decrease in size with increasing centrality is observed. Moreover, a comparison of results from Cu+Cu versus Au+Au collisions shows an interesting scaling of the effective cluster size with the measured fraction of total cross section (which is related to the ratio of the impact parameter to the nuclear radius, b/2R), suggesting a geometric origin. Further analysis for pairs from restricted azimuthal regions shows that the effective cluster size at {Delta}{phi}{approx}180 deg. drops more rapidly toward central collisions than the size at {Delta}{phi}{approx}0 deg. The effect of limited {eta} acceptance on the cluster parameters is also addressed, and a correction is applied to present cluster parameters for full {eta} coverage, leading to much larger effective cluster sizes and widths than previously noted in the literature. These results should provide insight into the hot and dense medium created in heavy ion collisions.

  1. Structural Studies of Al:ZnO Powders and Thin Films | Stanford...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    the ZnO lattice, and measure its effect on the crystallinity of thin films prepared by sol-gel techniques, with an aim to understand how these properties affect the film...

  2. Imaging and characterization of piezoelectric potential in a single bent ZnO microwire

    SciTech Connect (OSTI)

    Wang, Chiang-Lun; Chen, Jhih-Wei; Chen, Yi-Chun; Wu, Chung-Lin; Tsai, Shu-Ju; Lin, Kai-Hsiang; Hsu, Hsu-Cheng

    2014-09-22

    We achieved direct visualization of the piezoelectric potentials in a single bent ZnO microwire (MW) using focused synchrotron radiation (soft x-ray) scanning photoelectron spectro-microscopy. Using radial-line scan across the bent section of ZnO MW, the characteristic core-level shifts were directly related to the spatial distribution of piezoelectric potentials perpendicular to the ZnO polar direction. Using piezoelectric modeling in ZnO, we delineated the band structure distortion and carrier concentration change from tensile to compressed sides by combining the spatial resolved cathodoluminescence characteristics in an individual microwire. This spectro-microscopic technique allows imaging and identification of the electric-mechanical couplings in piezoelectric micro-/nano-wire systems.

  3. Determination of the spontaneous polarization of wurtzite (Mg,Zn)O

    SciTech Connect (OSTI)

    Stölzel, Marko Müller, Alexander; Benndorf, Gabriele; Lorenz, Michael; Grundmann, Marius; Patzig, Christian; Höche, Thomas

    2014-05-12

    We report on the experimental determination of the spontaneous polarization of wurtzite-(Mg,Zn)O by examination of the recombination dynamics of polar ZnO/(Mg,Zn)O quantum wells (QWs). The thickness-dependent decay time of the unscreened single-exciton states inside the QWs was modeled by a self-consistent solution of Schrödinger- and Poisson-equation to deduce the total polarization across the QW for different Mg-contents inside the barriers. By the separation of the piezoelectric components of the polarization, a linear increase in spontaneous polarization with increasing Mg-content x of P/x = (0.151 ± 0.015) C/m{sup 2} was determined for Mg{sub x} Zn{sub 1−x} O.

  4. Response-time improved hydrothermal-method-grown ZnO scintillator...

    Office of Scientific and Technical Information (OSTI)

    Response-time improved hydrothermal-method-grown ZnO scintillator for soft x-ray free-electron laser timing-observation Citation Details In-Document Search Title: Response-time...

  5. PEDOT-PSS coated ZnO/C hierarchical porous nanorods as ultralong...

    Office of Scientific and Technical Information (OSTI)

    PEDOT-PSS coated ZnOC hierarchical porous nanorods as ultralong-life anode material for lithium ion batteries This content will become publicly available on November 16, 2017 ...

  6. Electrical and structural properties of ZnO synthesized via infiltration of lithographically defined polymer templates

    SciTech Connect (OSTI)

    Chang-Yong Nam; Stein, Aaron; Kisslinger, Kim; Black, Charles T.

    2015-11-17

    We investigate the electrical and structural properties of infiltration-synthesized ZnO. In-plane ZnO nanowire arrays with prescribed positional registrations are generated by infiltrating diethlyzinc and water vapor into lithographically defined SU-8 polymer templates and removing organic matrix by oxygen plasma ashing. Transmission electron microscopy reveals that homogeneously amorphous as-infiltrated polymer templates transform into highly nanocrystalline ZnO upon removal of organic matrix. Field-effect transistor device measurements show that the synthesized ZnO after thermal annealing displays a typical n-type behavior, ~1019 cm-3 carrier density, and ~0.1 cm2 V-1 s-1 electron mobility, reflecting highly nanocrystalline internal structure. The results demonstrate the potential application of infiltration synthesis in fabricating metal oxide electronic devices.

  7. Electrical and structural properties of ZnO synthesized via infiltration of lithographically defined polymer templates

    SciTech Connect (OSTI)

    Nam, Chang-Yong Stein, Aaron; Kisslinger, Kim; Black, Charles T.

    2015-11-16

    We investigate the electrical and structural properties of infiltration-synthesized ZnO. In-plane ZnO nanowire arrays with prescribed positional registrations are generated by infiltrating diethlyzinc and water vapor into lithographically defined SU-8 polymer templates and removing organic matrix by oxygen plasma ashing. Transmission electron microscopy reveals that homogeneously amorphous as-infiltrated polymer templates transform into highly nanocrystalline ZnO upon removal of organic matrix. Field-effect transistor device measurements show that the synthesized ZnO after thermal annealing displays a typical n-type behavior, ∼10{sup 19 }cm{sup −3} carrier density, and ∼0.1 cm{sup 2} V{sup −1} s{sup −1} electron mobility, reflecting highly nanocrystalline internal structure. The results demonstrate the potential application of infiltration synthesis in fabricating metal oxide electronic devices.

  8. Band alignment and interfacial structure of ZnO/Si heterojunction...

    Office of Scientific and Technical Information (OSTI)

    Band alignment and interfacial structure of ZnOSi heterojunction with Alsub 2Osub 3 and HfOsub 2 as interlayers Citation Details In-Document Search Title: Band alignment and ...

  9. Synthesis of ZnO decorated graphene nanocomposite for enhanced photocatalytic properties

    SciTech Connect (OSTI)

    Gayathri, S.; Jayabal, P.; Kottaisamy, M.; Ramakrishnan, V.

    2014-05-07

    Zinc oxide/Graphene (GZ) composites with different concentrations of ZnO were successfully synthesized through simple chemical precipitation method. The X-ray diffraction pattern and the micro-Raman spectroscopic technique revealed the formation of GZ composite, and the energy dispersive X-ray spectrometry analysis showed the purity of the prepared samples. The ZnO nanoparticles decorated graphene sheets were clearly visible in the field emission scanning electron micrograph. Raman mapping was employed to analyze the homogeneity of the prepared samples. The diffuse-reflectance spectra clearly indicated that the formation of GZ composites promoted the absorption in the visible region also. The photocatalytic activity of ZnO and GZ composites was studied by the photodegradation of Methylene blue dye. The results revealed that the GZ composites exhibited a higher photocatalytic activity than pristine ZnO. Hence, we proposed a simple wet chemical method to synthesize GZ composite and its application on photocatalysis was demonstrated.

  10. Alignment nature of ZnO nanowires grown on polished and nanoscale...

    Office of Scientific and Technical Information (OSTI)

    * Self-alignment of the nanowires due to step bunching of LiNbOsub 3 surface is ... As-grown ZnO nanowires exhibited a crisscross aligned growth pattern due to step bunching ...

  11. Luminescence and electrical properties of single ZnO/MgO core/shell nanowires

    SciTech Connect (OSTI)

    Grinblat, Gustavo; Comedi, David; Bern, Francis; Barzola-Quiquia, Jos; Esquinazi, Pablo; Tirado, Mnica

    2014-03-10

    To neutralise the influence of the surface of ZnO nanowires for photonics and optoelectronic applications, we have covered them with insulating MgO film and individually contacted them for electrical characterisation. We show that such a metal-insulator-semiconductor-type nanodevice exhibits a high diode ideality factor of 3.4 below 1?V. MgO shell passivates ZnO surface states and provides confining barriers to electrons and holes within the ZnO core, favouring excitonic ultraviolet radiative recombination, while suppressing defect-related luminescence in the visible and improving electrical conductivity. The results indicate the potential use of ZnO/MgO nanowires as a convenient building block for nano-optoelectronic devices.

  12. Electrical and structural properties of ZnO synthesized via infiltration of lithographically defined polymer templates

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Chang-Yong Nam; Stein, Aaron; Kisslinger, Kim; Black, Charles T.

    2015-11-17

    We investigate the electrical and structural properties of infiltration-synthesized ZnO. In-plane ZnO nanowire arrays with prescribed positional registrations are generated by infiltrating diethlyzinc and water vapor into lithographically defined SU-8 polymer templates and removing organic matrix by oxygen plasma ashing. Transmission electron microscopy reveals that homogeneously amorphous as-infiltrated polymer templates transform into highly nanocrystalline ZnO upon removal of organic matrix. Field-effect transistor device measurements show that the synthesized ZnO after thermal annealing displays a typical n-type behavior, ~1019 cm-3 carrier density, and ~0.1 cm2 V-1 s-1 electron mobility, reflecting highly nanocrystalline internal structure. The results demonstrate the potential application ofmore » infiltration synthesis in fabricating metal oxide electronic devices.« less

  13. Single-valley quantum Hall ferromagnet in a dilute MgxZn1-xO/ZnO strongly correlated two-dimensional electron system

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Kozuka, Y.; Tsukazaki, A.; Maryenko, D.; Falson, J.; Bell, C.; Kim, M.; Hikita, Y.; Hwang, H. Y.; Kawasaki, M.

    2012-02-03

    We investigate the spin susceptibility (g*m*) of dilute two-dimensional (2D) electrons confined at the MgxZn1-xO/ZnO heterointerface. Magnetotransport measurements show a four-fold enhancement of g*m*, dominated by the increase in the Landé g-factor. The g-factor enhancement leads to a ferromagnetic instability of the electron gas as evidenced by sharp resistance spikes. At high magnetic field, the large g*m* leads to full spin polarization, where we found sudden increase in resistance around the filling factors of half-integer, accompanied by complete disappearance of fractional quantum Hall (QH) states. Along with its large effective mass and the high electron mobility, our result indicates thatmore » the ZnO 2D system is ideal for investigating the effect of electron correlations in the QH regime.« less

  14. OBSERVATIONS OF ISOTROPIC INTERSTELLAR PICK-UP IONS AT 11 AND 17 AU FROM NEW HORIZONS

    SciTech Connect (OSTI)

    Randol, B. M.; McComas, D. J.; Elliott, H. A.; Gosling, J. T.; Schwadron, N. A.

    2012-08-10

    We report new observations by the Solar Wind Around Pluto (SWAP) instrument on the New Horizons spacecraft of an energy-per-charge (E/q) spectrum of interstellar pick-up ions (PUIs) from an unprecedented heliocentric distance of 17 AU. This E/q spectrum is fit well by an isotropic PUI distribution function combined with the detailed response of the SWAP instrument. In contrast to earlier work, we are also able to fit an isotropic PUI model to an E/q spectrum measured by SWAP at 11.3 AU by explicitly including two additional effects. These are (1) the E/q-dependent geometric factor of SWAP, which increases with decreasing E/q owing to effects associated with the post-acceleration of particles exiting the electrostatic analyzer portion of the instrument; and (2) a solar wind distribution, the model spectrum of which contributes significantly to the low-E/q part of the overall model owing, presumably, to secondary particles produced within the instrument.

  15. Sintered Cr/Pt and Ni/Au ohmic contacts to B12P2

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Frye, Clint D.; Kucheyev, Sergei O.; Edgar, James H.; Voss, Lars F.; Conway, Adam M.; Shao, Qinghui; Nikolic, Rebecca J.

    2015-04-09

    With this study, icosahedral boron phosphide (B12P2) is a wide-bandgap semiconductor possessing interesting properties such as high hardness, chemical inertness, and the reported ability to self-heal from irradiation by high energy electrons. Here, the authors developed Cr/Pt and Ni/Au ohmic contacts to epitaxially grown B12P2 for materials characterization and electronic device development. Cr/Pt contacts became ohmic after annealing at 700 °C for 30 s with a specific contact resistance of 2×10–4 Ω cm2, as measured by the linear transfer length method. Ni/Au contacts were ohmic prior to any annealing, and their minimum specific contact resistance was ~l–4 × 10–4 Ωmore » cm2 after annealing over the temperature range of 500–800 °C. Rutherford backscattering spectrometry revealed a strong reaction and intermixing between Cr/Pt and B12P2 at 700 °C and a reaction layer between Ni and B12P2 thinner than ~25 nm at 500 °C.« less

  16. The (111) Surface of NaAu2. Structure, Composition, and Stability

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Kwolek, Emma J.; Widmer, Roland; Gröning, Oliver; Deniz, Okan; Walen, Holly; Yuen, Chad D.; Huang, Wenyu; Schlagel, Deborah L.; Wallingford, Mark; Thiel, Patricia A.

    2014-12-17

    The (111) surface of single-crystal NaAu2 is a model for catalytically active, powdered NaAu2. We prepare and characterize this surface with a broad suite of techniques. Preparation in ultrahigh vacuum consists of the traditional approach of ion bombardment (to remove impurities) and thermal annealing (to restore surface order). Both of these steps cause loss of sodium (Na), and repeated treatments eventually trigger conversion of the surface and near-surface regions to crystalline gold. The bulk has a limited ability to repopulate the surface Na. Under conditions where Na depletion is minimized, electron diffraction patterns are consistent with the bulk-terminated structure, andmore » scanning tunneling microscopy reveals mesa-like features with lateral dimensions of a few tens of nanometers. The tops of the mesas do not possess fine structure characteristic of a periodic lattice, suggesting that the surface layer is disordered under the conditions of these experiments.« less

  17. Low-temperature aqueous-phase reforming of ethanol on bimetallic PdZn catalysts

    SciTech Connect (OSTI)

    Xiong, Haifeng; DelaRiva, Andrew; Wang, Yong; Dayte, Abhaya

    2015-01-01

    Bimetallic PdZn catalysts supported on carbon black (CB) and carbon nanotubes (CNTs) were found to be selective for CO-free H-2 production from ethanol at low temperature (250 degrees C). On Pd, the H-2 yield was low (similar to 0.3 mol H-2/mol ethanol reacted) and the CH4/CO2 ratio was high (similar to 1.7). Addition of Zn to Pd formed the intermetallic PdZn beta phase (atomic ratio of Zn to Pd is 1) with increased H-2 yield (similar to 1.9 mol H-2/mol ethanol reacted) and CH4/CO2 ratio of <1. The higher H-2 yield and low CH4 formation was related to the improved dehydrogenation activity of the L1(0) PdZn beta phase. The TOF increased with particle size and the CNTs provided the most active and selective catalysts, which may be ascribed to pore-confinement effects. Furthermore, no significant changes in either the supports or the PdZn beta particles was found after aqueous-phase reforming (APR) indicating that the metal nanoparticles and the carbon support are hydrothermally stable in the aqueous phase at elevated temperatures and pressures (>200 degrees C, 65 bar). No CO was detected for all the catalysts performed in aqueous-phase reaction, indicating that both monometallic Pd and bimetallic PdZn catalysts have high water-gas shift activity during APR. However, the yield of H-2 is considerably lower than the theoretical value of 6 H-2 per mole ethanol which is due to the presence of oxygenated products and methane on the PdZn catalysts.

  18. Thin-film polycrystalline n-ZnO/p-CuO heterojunction

    SciTech Connect (OSTI)

    Lisitski, O. L.; Kumekov, M. E.; Kumekov, S. E. Terukov, E. I.

    2009-06-15

    Results of X-ray diffraction and spectral-optical studies of n-ZnO and p-CuO films deposited by gas-discharge sputtering with subsequent annealing are presented. It is shown that, despite the difference in the crystal systems, the polycrystallinity of n-ZnO and p-CuO films enables fabrication of a heterojunction from this pair of materials.

  19. Self-assembled ultra small ZnO nanocrystals for dye-sensitized solar cell application

    SciTech Connect (OSTI)

    Patra, Astam K.; Dutta, Arghya; Bhaumik, Asim

    2014-07-01

    We demonstrate a facile chemical approach to produce self-assembled ultra-small mesoporous zinc oxide nanocrystals using sodium salicylate (SS) as a template under hydrothermal conditions. These ZnO nanomaterials have been successfully fabricated as a photoanode for the dye-sensitized solar cell (DSSC) in the presence of N719 dye and iodinetriiodide electrolyte. The structural features, crystallinity, purity, mesophase and morphology of the nanostructure ZnO are investigated by several characterization tools. N{sub 2} sorption analysis revealed high surface areas (203 m{sup 2} g{sup ?1}) and narrow pore size distributions (5.15.4 nm) for different samples. The mesoporous structure and strong photoluminescence facilitates the high dye loading at the mesoscopic void spaces and light harvesting in DSSC. By utilizing this ultra-small ZnO photoelectrode with film thickness of about 7 ?m in the DSSC with an open-circuit voltage (V{sub OC}) of 0.74 V, short-circuit current density (J{sub SC}) of 3.83 mA cm{sup ?2} and an overall power conversion efficiency of 1.12% has been achieved. - Graphical abstract: Ultra-small ZnO nanocrystals have been synthesized with sodium salicylate as a template and using it as a photoanode in a dye-sensitized solar cell 1.12% power conversion efficiency has been observed. - Highlights: Synthesis of self-assembled ultra-small mesoporous ZnO nanocrystals by using sodium salicylate as a template. Mesoporous ZnO materials have high BET surface areas and void space. ZnO nanoparticles serve as a photoanode for the dye-sensitized solar cell (DSSC). Using ZnO nanocrystals as photoelectrode power conversion efficiency of 1.12% has been achieved.

  20. Characterization of Aerosols Containing Zn, Pb, and Cl from an Industrial Region of Mexico City

    SciTech Connect (OSTI)

    Moffet, Ryan C.; Desyaterik, Yury; Hopkins, Rebecca J.; Tivanski, Alexei V.; Gilles, Marry K.; Wang, Yan A.; Shutthanandan, V.; Molina, Luisa T.; Abraham, Rodrigo G.; Johnson, Kirsten S.; Mugica, Violeta; Molina, Mario J.; Laskin, Alexander; Prather, Kimberly A.

    2008-10-01

    During the March, 2006 MILAGRO campaign, measurements in the Northern Mexico City Metropolitan Area revealed the frequent appearance of particles with a characteristically high content of internally mixed Zn, Pb, Cl, and P. A comprehensive study of the chemical and physical properties of these particles was performed using a complementary combination of aerosol measurement techniques. Individual particles were analyzed using Aerosol Time-of-Flight Mass Spectrometry (ATOFMS) and Computer Controlled Scanning Electron Microscopy/Energy Dispersive X-Ray spectroscopy (CCSEM/EDX). Proton Induced X-Ray Emission (PIXE) analysis of bulk aerosol samples provided time-resolved mass concentrations of individual elements. The PIXE measurements indicated that Zn is more strongly correlated with Cl than with any other element and that Zn concentrations are higher than other non-ferrous transition metals. The Zn- and Pb - containing particles have both spherical and non-spherical morphologies. Many metal rich particles had needle-like structures and were found to be composed of ZnO and/or Zn(NO3)2?6H2O as indicated by scanning transmission x-ray microscopy/near edge X-ray absorption spectroscopy (STXM/NEXAFS). The Zn and Pb rich particles were primarily in the submicron size range and internally mixed with elemental carbon. The unique chemical associations most closely match signatures acquired for garbage incineration. This unique combination of complementary analytical techniques has allowed for a comprehensive evaluation of Zn- and Pb- containing particles in a complex urban environment, highlighting unique characteristics that give powerful insight into their origin.

  1. Facile synthesis of pompon-like ZnO-Ag nanocomposites and their enhanced photocatalytic performance

    SciTech Connect (OSTI)

    Cheng, Yang; An, Liang; Lan, Jing; Gao, Fang; Tan, Ruiqin; Li, Xiao-min; Wang, Guang-hui

    2013-10-15

    Graphical abstract: - Highlights: • Pompon-like ZnO-Ag was prepared via heterothermal and photodeposition method. • Pompon-like ZnO-Ag is a excellent photocatalyst for degradation of azo dyes. • The photocatalytic and wetting properties were studied upon UV irradiation. • The discoloring efficiency of ZnO-Ag heterostructure toward to azo dyes is 99.1%. - Abstract: A series of pompon-like ZnO-Ag nanocomposites were prepared by hydrothermal method and photochemical deposition technique. Several characterizations indicated the successful deposition of Ag nanoparticles on ZnO. As a whole, the as-prepared composites present pompon-like nanostructures with a diameter of ∼10 μm. In detail, the nanostructural, chemical and optical properties were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), infrared spectroscopy (IR), ultra-visible spectra (UV). The photocatalytic degradation experiments under UV irradiation using Methyl Orange (MO) as a model dye were executed here. The relative results demonstrated that the pompon-like ZnO-Ag nanocomposite with a suitable content of Ag nanoparticles (about 4.82 wt%) has the highest photochemical activity, and the removal ratio of MO was 99.1% after 0.5 h adsorption and subsequent 2 h photodegradation processes. The excellent photocatalytic performance was attributed to the high surface areas of ZnO nanostructure and effectively separation of photo-generated charge on flower-like ZnO by employing Ag nanoparticles as a conductor.

  2. Synthesis of highly efficient antibacterial agent Ag doped ZnO nanorods: Structural, Raman and optical properties

    SciTech Connect (OSTI)

    Jan, Tariq; Iqbal, Javed; Ismail, Muhammad; Mahmood, Arshad

    2014-04-21

    Here, synthesis, structural, morphological, Raman, optical properties and antibacterial activity of undoped and Ag doped ZnO nanorods by chemical co-precipitation technique have been reported. Structural analysis has revealed that Ag doping cannot deteriorate the structure of ZnO and wurtzite phase is maintained. Lattice constants are found to be decreased with the Ag doping. Fourier transform infrared and Raman spectroscopy also confirm the X-ray diffraction results. Scanning electron microscopy results have demonstrated the formation of ZnO nanorods with average diameter and length of 96 nm and 700 nm, respectively. Raman spectroscopy results suggest that the Ag doping enhances the number of defects in ZnO crystal. It has been found from optical study that Ag doping results in positional shift of band edge absorption peak. This is attributed to the successful incorporation of Ag dopant into ZnO host matrix. The antibacterial activity of prepared nanorods has been determined by two different methods and compared to that of undoped ZnO nanorods. Ag doped ZnO nanorods exhibit excellent antibacterial activity as compared to that of undoped ZnO nanorods. This excellent antibacterial activity may be attributed to the presence of oxygen vacancies and Zn{sup 2+} interstitial defects. Our preliminary findings suggest that Ag doped ZnO nanorods can be used externally to control the spreading of infections related with tested bacterial strains.

  3. Zn speciation in a soil contaminated by the deposition of a dredged sediment by synchrotron X-ray techniques

    SciTech Connect (OSTI)

    Isaure, Marie-Pierre; Manceau, Alain; Laboudigue, Agnes; Tamura, Nobumichi; Marcus, Matthew A.

    2003-09-01

    The nature and proportion of Zn species present in an agricultural soil overlaid by a dredged contaminated sediment have been untangled by the novel combination of three non-invasive synchrotron-based x-ray techniques: x-ray microfluorescence ({mu}SXRF), microdiffraction ({mu}XRD), and absorption spectroscopy (EXAFS). One primary (franklinite) and two secondary (phyllomanganate and phyllosilicate) Zn-containing minerals were identified in the initial soil, and another primary (ZnS) and a new secondary (Fe-(oxyhydr)oxide) Zn species in the covered soil. The quantitative analysis of EXAFS spectra recorded on bulk samples indicated that ZnS and Zn-Fe (oxyhydr)oxides amounted to 71+-10 percent and 27+-10 percent, respectively, and the other Zn species to less than 10 percent. The two new Zn species found in the covered soil result from the gravitational migration of ZnS particles initially present in the sediment, and from their further oxidative dissolution and fixation of leached Zn on F e (oxyhydr) oxides.

  4. Au133(SPh-tBu)52 Nanomolecules: X-ray Crystallography, Optical, Electrochemical, and Theoretical Analysis

    SciTech Connect (OSTI)

    Dass, Amala; Theivendran, Shevanuja; Nimmala, Praneeth Reddy; Kumara, Chanaka; Jupally, Vijay Reddy; Fortunelli, Alessandro; Sementa, Luca; Barcaro, Giovanni; Zuo, Xiaobing; Noll, Bruce C.

    2015-04-15

    Crystal structure determination has revolutionized modern science in biology, chemistry, and physics. However, the difficulty in obtaining periodic crystal lattices which are needed for X-ray crystal analysis has hindered the determination of atomic structure in nanomaterials, known as the nanostructure problem. Here, by using rigid and bulky ligands, we have overcome this limitation and successfully solved the X-ray crystallographic structure of the largest reported thiolated gold nanomolecule, Au133S52. The total composition, Au133(SPh-tBu)52, was verified using high resolution electrospray ionization mass spectrometry (ESI-MS). The experimental and simulated optical spectra show an emergent surface plasmon resonance that is more pronounced than in the slightly larger Au144(SCH2CH2Ph)60. Theoretical analysis indicates that the presence of rigid and bulky ligands is the key to the successful crystal formation.

  5. Ab initio study of MXe{sub n}{sup +} (M=Cu, Ag, and Au; n=1,2)

    SciTech Connect (OSTI)

    Li Xinying; Cao Xue

    2008-02-15

    The equilibrium geometries, vibrational frequencies, dissociation energies, and populations of the title species were studied at Hartree-Fock (HF), second-order Moeller-Plesset (MP2), and coupled-cluster singles-doubles (triples) [CCSD(T)] levels. The electron correlation effects and relativistic effects on the geometry and stability were investigated at the CCSD(T) level. Both effects stabilize title species. The populations analyses show that M-Xe bonding is dominated by electrostatic interactions and the best theoretical estimate of the dissociation energies are 1.104 and 2.260 eV for AuXe{sup +} and AuXe{sub 2}{sup +}, respectively. The Cu and Ag are weakly bonded to Xe compared to Au.

  6. Adsorption and switching properties of a N-benzylideneaniline based molecular switch on a Au(111) surface

    SciTech Connect (OSTI)

    Ovari, Laszlo; Luo, Ying; Haag, Rainer; Leyssner, Felix; Tegeder, Petra; Wolf, Martin

    2010-07-28

    High resolution electron energy loss spectroscopy has been employed to analyze the adsorption geometry and the photoisomerization ability of the molecular switch carboxy-benzylideneaniline (CBA) adsorbed on Au(111). CBA on Au(111) adopts a planar (trans) configuration in the first monolayer (ML) as well as for higher coverages (up to 6 ML), in contrast to the strongly nonplanar geometry of the molecule in solution. Illumination with UV light of CBA in direct contact with the Au(111) surface ({<=}1 ML) caused no changes in the vibrational structure, whereas at higher coverages (>1 ML) pronounced modifications of vibrational features were observed, which we assign to a trans{yields}cis isomerization. Thermal activation induced the back reaction to trans-CBA. We propose that the photoisomerization is driven by a direct (intramolecular) electronic excitation of the adsorbed CBA molecules in the second ML (and above) analogous to CBA in the liquid phase.

  7. Determination of reactive oxygen species from ZnO micro-nano structures with shape-dependent photocatalytic activity

    SciTech Connect (OSTI)

    He, Weiwei; Zhao, Hongxiao; Jia, Huimin; Yin, Jun-Jie; Zheng, Zhi

    2014-05-01

    Graphical abstract: ZnO micro/nano structures with shape dependent photocatalytic activity were prepared by hydrothermal reaction. The generations of hydroxyl radical, superoxide and singlet oxygen from irradiated ZnO were identified precisely by electron spin resonance spectroscopy. The type of reactive oxygen species was determined by band gap structure of ZnO. - Highlights: ZnO micro/nano structures with different morphologies were prepared by solvothermal reaction. Multi-pod like ZnO structures exhibited superior photocatalytic activity. The generations of hydroxyl radical, superoxide and singlet oxygen from irradiated ZnO were characterized precisely by electron spin resonance spectroscopy. The type of reactive oxygen species was determined by band gap structure of ZnO. - Abstract: ZnO micro/nano structures with different morphologies have been prepared by the changing solvents used during their synthesis by solvothermal reaction. Three typical shapes of ZnO structures including hexagonal, bell bottom like and multi-pod formed and were characterized by scanning electron microscopy and X-ray diffraction. Multi pod like ZnO structures exhibited the highest photocatalytic activity toward degradation of methyl orange. Using electron spin resonance spectroscopy coupled with spin trapping techniques, we demonstrate an effective way to identify precisely the generation of hydroxyl radicals, superoxide and singlet oxygen from the irradiated ZnO multi pod structures. The type of reactive oxygen species formed was predictable from the band gap structure of ZnO. These results indicate that the shape of micro-nano structures significantly affects the photocatalytic activity of ZnO, and demonstrate the value of electron spin resonance spectroscopy for characterizing the type of reactive oxygen species formed during photoexcitation of semiconductors.

  8. Effects of hydrogen on the optical properties of ZnCdO/ZnO quantum wells grown by molecular beam epitaxy

    SciTech Connect (OSTI)

    Buyanova, I. A.; Wang, X. J.; Chen, W. M.; Pozina, G.; Lim, W.; Norton, D. P.; Pearton, S. J.; Osinsky, A.; Dong, J. W.; Hertog, B.

    2008-06-30

    Temperature-dependent cw- and time-resolved photoluminescence (PL), as well as optically detected magnetic resonance (ODMR) measurements are employed to evaluate effects of deuterium (2H) doping on optical properties of ZnCdO/ZnO quantum well structures grown by molecular beam epitaxy. It is shown that incorporation of {sup 2}H from a remote plasma causes a substantial improvement in radiative efficiency of the investigated structures. Based on transient PL measurements, the observed improvements are attributed to efficient passivation by hydrogen of competing nonradiative recombination centers via defects. This conclusion is confirmed from the ODMR studies.

  9. A novel investigation on carbon nanotube/ZnO, Ag/ZnO and Ag/carbon nanotube/ZnO nanowires junctions for harvesting piezoelectric potential on textile

    SciTech Connect (OSTI)

    Khan, Azam Edberg, Jesper; Nur, Omer; Willander, Magnus

    2014-07-21

    In the present work, three junctions were fabricated on textile fabric as an alternative substrate for harvesting piezoelectric potential. First junction was formed on ordinary textile as (textile/multi-walled carbon nanotube film/zinc oxide nanowires (S1: T/CNTs/ZnO NWs)) and the other two were formed on conductive textile with the following layer sequence: conductive textile/zinc oxide nanowires (S2: CT/ZnO NWs) and conductive textile/multi-walled carbon nanotubes film/zinc oxide nanowires (S3: CT/CNTs/ZnO NWs). Piezoelectric potential was harvested by using atomic force microscopy in contact mode for the comparative analysis of the generated piezoelectric potential. ZnO NWs were synthesized by using the aqueous chemical growth method. Surface analysis of the grown nanostructures was performed by using scanning electron microscopy and transmission electron microscopy. The growth orientation and crystalline size were studied by using X-ray diffraction technique. This study reveals that textile as an alternative substrate have many features like cost effective, highly flexible, nontoxic, light weight, soft, recyclable, reproducible, portable, wearable, and washable for nanogenerators fabrication with acceptable performance and with a wide choice of modification for obtaining large amount of piezoelectric potential.

  10. Hydroquinone-ZnO nano-laminate deposited by molecular-atomic layer deposition

    SciTech Connect (OSTI)

    Huang, Jie; Lucero, Antonio T.; Cheng, Lanxia; Kim, Jiyoung; Hwang, Hyeon Jun; Ha, Min-Woo

    2015-03-23

    In this study, we have deposited organic-inorganic hybrid semiconducting hydroquinone (HQ)/zinc oxide (ZnO) superlattices using molecular-atomic layer deposition, which enables accurate control of film thickness, excellent uniformity, and sharp interfaces at a low deposition temperature (150 °C). Self-limiting growth of organic layers is observed for the HQ precursor on ZnO surface. Nano-laminates were prepared by varying the number of HQ to ZnO cycles in order to investigate the physical and electrical effects of different HQ to ZnO ratios. It is indicated that the addition of HQ layer results in enhanced mobility and reduced carrier concentration. The highest Hall mobility of approximately 2.3 cm{sup 2}/V·s and the lowest n-type carrier concentration of approximately 1.0 × 10{sup 18}/cm{sup 3} were achieved with the organic-inorganic superlattice deposited with a ratio of 10 ZnO cycles to 1 HQ cycle. This study offers an approach to tune the electrical transport characteristics of ALD ZnO matrix thin films using an organic dopant. Moreover, with organic embedment, this nano-laminate material may be useful for flexible electronics.

  11. Ferromagnetism in Gd doped ZnO nanowires: A first principles study

    SciTech Connect (OSTI)

    Aravindh, S. Assa; Schwingenschloegl, Udo E-mail: iman.roqan@kaust.edu.sa; Roqan, Iman S. E-mail: iman.roqan@kaust.edu.sa

    2014-12-21

    In several experimental studies, room temperature ferromagnetism in Gd-doped ZnO nanostructures has been achieved. However, the mechanism and the origin of the ferromagnetism remain controversial. We investigate the structural, magnetic, and electronic properties of Zn{sub 48}O{sub 48} nanowires doped with Gd, using density functional theory. Our findings indicate that substitutionally incorporated Gd atoms prefer occupying the surface Zn sites. Moreover, the formation energy increases with the distance between Gd atoms, signifying that no Gd-Gd segregation occurs in the nanowires within the concentration limit of ≤2%. Gd induces ferromagnetism in ZnO nanowires with magnetic coupling energy up to 21 meV in the neutral state, which increases with additional electron and O vacancy, revealing the role of carriers in magnetic exchange. The potential for achieving room temperature ferromagnetism and high T{sub C} in ZnO:Gd nanowires is evident from the large ferromagnetic coupling energy (200 meV) obtained with the O vacancy. Density of states shows that Fermi level overlaps with Gd f states with the introduction of O vacancy, indicating the possibility of s-f coupling. These results will assist in understanding experimental findings in Gd-doped ZnO nanowires.

  12. Nucleation and growth of ZnO on PMMA by low-temperature atomic layer deposition

    SciTech Connect (OSTI)

    Napari, Mari Malm, Jari; Lehto, Roope; Julin, Jaakko; Arstila, Kai; Sajavaara, Timo; Lahtinen, Manu

    2015-01-15

    ZnO films were grown by atomic layer deposition at 35?C on poly(methyl methacrylate) substrates using diethylzinc and water precursors. The film growth, morphology, and crystallinity were studied using Rutherford backscattering spectrometry, time-of-flight elastic recoil detection analysis, atomic force microscopy, scanning electron microscopy, and x-ray diffraction. The uniform film growth was reached after several hundreds of deposition cycles, preceded by the precursor penetration into the porous bulk and island-type growth. After the full surface coverage, the ZnO films were stoichiometric, and consisted of large grains (diameter 30?nm) with a film surface roughness up to 6?nm (RMS). The introduction of Al{sub 2}O{sub 3} seed layer enhanced the initial ZnO growth substantially and changed the surface morphology as well as the crystallinity of the deposited ZnO films. Furthermore, the water contact angles of the ZnO films were measured, and upon ultraviolet illumination, the ZnO films on all the substrates became hydrophilic, independent of the film crystallinity.

  13. Facile combustion synthesis of ZnO nanoparticles using Cajanus cajan (L.) and its multidisciplinary applications

    SciTech Connect (OSTI)

    Manjunath, K.; Ravishankar, T.N.; Kumar, Dhanith; Priyanka, K.P; Varghese, Thomas; Naika, H.Raja; Nagabhushana, H.; Sharma, S.C.; Dupont, J.; Ramakrishnappa, T.; Nagaraju, G.

    2014-09-15

    Graphical abstract: Facile combustion synthesis of ZnO nanoparticles using Cajanuscajan (L.) and its multidisciplinary applications.Zinc oxide nanoparticles were successfully synthesized by solution combustion method (SCM) using pigeon pea as a combustible fuel for the first time. The as-prepared product shows good photocatalytic, dielectric, antibacterial, electrochemical properties. - Highlights: • ZnO Nps were synthesized via combustion method using pigeon pea as a fuel. • The structure of the product was confirmed by XRD technique. • The morphology was confirmed by SEM and TEM images. • The as-prepared product shown good photocatalytic activity, dielectric property. • It has also shown good antibacterial and electrochemical properties. - Abstract: Zinc oxide nanoparticles (ZnO Nps) were successfully synthesized by solution combustion method (SCM) using pigeon pea as a fuel for the first time. X-Ray diffraction pattern reveals that the product belongs to hexagonal system. FTIR spectrum of ZnO Nps shows the band at 420 cm{sup −1} associated with the characteristic vibration of Zn–O. TEM images show that the nanoparticles are found to be ∼40–80 nm. Furthermore, the as-prepared ZnO Nps exhibits good photocatalytic activity for the photodegradation of methylene blue (MB), indicating that they are indeed a promising photocatalytic semiconductor. The antibacterial properties of ZnO nanopowders were investigated by their bactericidal activity against four bacterial strains.

  14. Effects of Zn additions to highly magnetoelastic FeGa alloys

    SciTech Connect (OSTI)

    Lograsso, Thomas A.; Jones, Nicholas J.; Wun-Fogle, Marilyn; Restorff, James B.; Schlagel, Deborah L.; Petculescu, Gabriela; Clark, Arthur E.; Hathaway, Kristl B.

    2015-05-07

    Fe{sub 1−x}M{sub x} (M = Ga, Ge, Si, Al, Mo and x ∼ 0.18) alloys offer an extraordinary combination of magnetoelasticity and mechanical properties. They are rare-earth-free, can be processed using conventional deformation techniques, have high magnetic permeability, low hysteresis, and low magnetic saturation fields, making them attractive for device applications such as actuators and energy harvesters. Starting with Fe-Ga as a reference and using a rigid-band-filling argument, Zhang et al. predicted that lowering the Fermi level by reducing the total number of electrons could enhance magnetoelasticity. To provide a direct experimental validation for Zhang's hypothesis, elemental additions with lower-than-Ga valence are needed. Of the possible candidates, only Be and Zn have sufficient solubility. Single crystals of bcc Fe-Ga-Zn have been grown with up to 4.6 at. % Zn in a Bridgman furnace under elevated pressure (15 bars) in order to overcome the high vapor pressure of Zn and obtain homogeneous crystals. Single-crystal measurements of magnetostriction and elastic constants allow for the direct comparison of the magnetoelastic coupling constants of Fe-Ga-Zn with those of other magnetoelastic alloys in its class. The partial substitution of Ga with Zn yields values for the magnetoelastic coupling factor, −b{sub 1}, comparable to those of the binary Fe-Ga alloy.

  15. Platelets to rings: Influence of sodium dodecyl sulfate on Zn-Al layered double hydroxide morphology

    SciTech Connect (OSTI)

    Yilmaz, Ceren; Unal, Ugur; Yagci Acar, Havva

    2012-03-15

    In the current study, influence of sodium dodecyl sulfate (SDS) on the crystallization of Zn-Al layered double hydroxide (LDH) was investigated. Depending on the SDS concentration coral-like and for the first time ring-like morphologies were obtained in a urea-hydrolysis method. It was revealed that the surfactant level in the starting solution plays an important role in the morphology. Concentration of surfactant equal to or above the anion exchange capacity of the LDH is influential in creating different morphologies. Another important parameter was the critical micelle concentration (CMC) of the surfactant. Surfactant concentrations well above CMC value resulted in ring-like structures. The crystallization mechanism was discussed. - Graphical abstract: Dependence of ZnAl LDH Morphology on SDS concentration. Highlights: Black-Right-Pointing-Pointer In-situ intercalation of SDS in ZnAl LDH was achieved via urea hydrolysis method. Black-Right-Pointing-Pointer Morphology of ZnAl LDH intercalated with SDS depended on the SDS concentration. Black-Right-Pointing-Pointer Ring like morphology for SDS intercalated ZnAl LDH was obtained for the first time. Black-Right-Pointing-Pointer Growth mechanism was discussed. Black-Right-Pointing-Pointer Template assisted growth of ZnAl LDH was proposed.

  16. The Golden Crown: A Single Au Atom that Boosts the CO Oxidation Catalyzed by a Palladium Cluster on Titania Surfaces

    SciTech Connect (OSTI)

    Zhang, Jin; Alexandrova, Anastassia N.

    2013-07-18

    We show that at the subnano scale, the catalytic properties of surface-supported clusters can be majorly impacted by strategic doping and the choice for the supporting surface. This is a first-principles investigation of CO oxidation catalyzed by two subnanoclusters, Pd4Au and Pd5, deposited on rutile TiO2(110) surfaces. The titania surface was found to participate in the reaction directly via providing additional reaction pathways. The bimetallic cluster Pd4Au shows enhanced catalytic activity, whereas the monometallic Pd5 is poisoned and deactivated in the presence of CO and oxygen, and this trend is reversed from that in the gas phase.

  17. Role of magnetism in superconductivity of BaFe2As2: Study of 5d Au-doped crystals

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Li, Li; Cao, Huibo; McGuire, Michael A.; Kim, J. S.; Stewart, G. R.; Sefat, Athena Safa

    2015-09-09

    We investigate properties of BaFe2As2 (122) single crystals upon gold doping, which is the transition metal with the highest atomic weight. The Au substitution into the FeAs-planes of 122 crystal structure (Au-122) is only possible up to a small amount of ~3%. We find that 5d is more effective in reducing magnetism in 122 than its counter 3d Cu, and this relates to superconductivity. We provide evidence of short-range magnetic fluctuations and local lattice inhomogeneities that may prevent strong percolative superconductivity in Ba(Fe1-xAux)2As2.

  18. Optical injection probing of single ZnO tetrapod lasers

    SciTech Connect (OSTI)

    Szarko, Jodi M.; Song, Jae Kyu; Blackledge, Charles Wesley; Swart, Ingmar; Leone, Stephen R.; Li, Shihong; Zhao, Yiping

    2004-11-23

    The properties of zinc oxide (ZnO) nanotetrapod lasers are characterized by a novel ultrafast two-color pump/stimulated emission probe technique. Single legs of tetrapod species are isolated by a microscope objective, pumped by 267 nm pulses, and subjected to a time-delayed 400 nm optical injection pulse, which permits investigation of the ultrafast carrier dynamics in the nanosize materials. With the optical injection pulse included, a large increase in the stimulated emission at 400 nm occurs, which partially depletes the carriers at this wavelength and competes with the normal 390 nm lasing. At the 390 nm lasing wavelengths, the optical injection causes a decrease in the stimulated emission due to the energetic redistribution of the excited carrier depletion, which occurs considerably within the time scale of the subpicosecond duration of the injection pulse. The effects of the optical injection on the spectral gain are employed to probe the lasing dynamics, which shows that the full width at half maximum of the lasing time is 3 ps.

  19. LiF/ZnS Neutron Multiplicity Counter

    SciTech Connect (OSTI)

    Stave, Sean C.; Bliss, Mary; Kouzes, Richard T.; Lintereur, Azaree T.; Robinson, Sean M.; Siciliano, Edward R.; Wood, Lynn S.

    2015-06-01

    Abstract: Alternatives to the use of 3He for the detection of thermal neutrons are being investigated. One of the most challenging applications for 3He alternatives is in neutron multiplicity counters. Neutron multiplicity counters are used to provide rapid assay of samples which contain an unknown amount of plutonium in a potentially unknown configuration. With appropriate detector design, the neutron single, double, and triple coincidence events can be used to extract information of three unknown parameters such as the 240Pu-effective mass, the sample self-multiplication, and the (α,n) rate. A project at PNNL has investigated replacing 3He-based tubes with LiF/ZnS neutron-scintillator sheets and wavelength shifting plastic for light pipes. A four-panel demonstrator module has been constructed, tested, and compared with detailed modeling results. The findings indicate that a full-scale system can be constructed with the same overall size as the most efficient 3He-based system and with improved performance. Remaining design challenges include electronics and robust neutron/gamma-ray discrimination based on pulse shape analysis at high rates. A review of the current effort and the most recent findings will be presented.

  20. Structural and optical properties of ZnO: K synthesized by sol-gel auto-combustion route

    SciTech Connect (OSTI)

    Krithiga, R. Sankar, S.; Subhashree, G.; Bharathi, R. Niruban

    2015-06-24

    The structural and optical behavior of ZnO and ZnO doped with K synthesized by solution combustion route is reported in this article. The XRD patterns confirm the substitution of K atoms into ZnO lattice. There are no secondary peaks observed in the XRD patterns. The band gap of the K doped samples show a red shift on comparison with the bandgap of ZnO. The photoluminescence spectral study discloses the quenching behavior of UV emission and the aggrandizing blue emission when K content increases. The rich presence of defects is confirmed from the optical analysis and a practical mechanism, involving Zn{sub i} for the origin of the blue emission in ZnO is discussed here.

  1. Nuclear matter effects on J/ψ production in asymmetric Cu + Au collisions at \\(\\sqrt{s_{\\mathrm{NN}}} = 200\\) GeV

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Adare, A.; Aidala, C.; Ajitanand, N. N.; Akiba, Y.; Akimoto, R.; Alexander, J.; Alfred, M.; Aoki, K.; Apadula, N.; Aramaki, Y.; et al

    2014-12-18

    We report on J/ψ production from asymmetric Cu+Au heavy-ion collisions at \\(\\sqrt{s_{\\mathrm{NN}}} = 200\\) GeV at the Relativistic Heavy Ion Collider at both forward (Cu-going direction) and backward (Au-going direction) rapidities. The nuclear modification of J/ψ yields in Cu+Au collisions in the Au-going direction is found to be comparable to that in Au+Au collisions when plotted as a function of the number of participating nucleons. In the Cu-going direction, J/ψ production shows a stronger suppression. This difference is comparable in magnitude and has the same sign as the difference expected from shadowing effects due to stronger low-x gluon suppression inmore » the larger Au nucleus. Thus, the relative suppression is opposite to that expected from hot nuclear matter dissociation, since a higher energy density is expected in the Au-going direction.« less

  2. Doping of ZnO nanowires using phosphorus diffusion from a spin-on doped glass source

    SciTech Connect (OSTI)

    Bocheux, A.; Robin, I. C.; Bonaimé, J.; Hyot, B.; Feuillet, G.; Kolobov, A. V.; Fons, P.; Mitrofanov, K. V.; Tominaga, J.; Tamenori, Y.

    2014-05-21

    In this article, we report on ZnO nanowires that were phosphorus doped using a spin on dopant glass deposition and diffusion method. Photoluminescence measurements suggest that this process yields p-doped ZnO. The spatial location of P atoms was studied using x-ray near-edge absorption structure spectroscopy and it is concluded that the doping is amphoteric with P atoms located on both Zn and O sites.

  3. Gold-rich R3Au7Sn3: Establishing the interdependence between electronic features and physical properties

    SciTech Connect (OSTI)

    Provino, Alessia; Steinberg, Simon; Smetana, Volodymyr; Kulkarni, Ruta; Dhar, Sudesh K.; Manfrinetti, Pietro; Mudring, Anja -Verena

    2015-05-18

    Two new polar intermetallic compounds Y3Au7Sn3 (I) and Gd3Au7Sn3 (II) have been synthesized and their structures have been determined by single crystal X-ray diffraction (P63/m; Z = 2, a = 8.148(1)/8.185(3), and c = 9.394(2)/9.415(3) for I/II, respectively). They can formally be assigned to the Cu10Sn3 type and consist of parallel slabs of Sn centered, edge-sharing trigonal Au6 antiprisms connected through R3 (R = Y, Gd) triangles. Additional Au atoms reside in the centres of trigonal Au6 prisms forming Au@Au6 clusters with Au–Au distances of 2.906–2.960 Å, while the R–R contacts in the R3 groups are considerably larger than the sums of their metallic radii. These exclusive structural arrangements provide alluring systems to study the synergism between strongly correlated systems, particularly, those in the structure of (II), and extensive polar intermetallic contacts, which has been inspected by measurements of the magnetic properties, heat capacities and electrical conductivities of both compounds. Gd3Au7Sn3 shows an antiferromagnetic ordering at 13 K, while Y3Au7Sn3 is a Pauli paramagnet and a downward curvature in its electrical resistivity at about 1.9 K points to a superconducting transition. DFT-based band structure calculations on R3Au7Sn3 (R = Y, Gd) account for the results of the conductivity measurements and different spin ordering models of (II) provide conclusive hints about its magnetic structure. As a result, chemical bonding analyses of both compounds indicate that the vast majority of bonding originates from the heteroatomic Au–Gd and Au–Sn interactions, while homoatomic Au–Au bonding is evident within the Au@Au6 clusters.

  4. Gold-rich R3Au7Sn3: Establishing the interdependence between electronic features and physical properties

    SciTech Connect (OSTI)

    Provino, Alessia; Steinberg, Simon; Smetana, Volodymyr; Kulkarni, Ruta; Dhar, Sudesh K.; Manfrinetti, Pietro; Mudring, Anja -Verena

    2015-05-18

    Two new polar intermetallic compounds Y3Au7Sn3 (I) and Gd3Au7Sn3 (II) have been synthesized and their structures have been determined by single crystal X-ray diffraction (P63/m; Z = 2, a = 8.148(1)/8.185(3), and c = 9.394(2)/9.415(3) for I/II, respectively). They can formally be assigned to the Cu10Sn3 type and consist of parallel slabs of Sn centered, edge-sharing trigonal Au6 antiprisms connected through R3 (R = Y, Gd) triangles. Additional Au atoms reside in the centres of trigonal Au6 prisms forming Au@Au6 clusters with Au–Au distances of 2.906–2.960 Å, while the R–R contacts in the R3 groups are considerably larger than the sums of their metallic radii. These exclusive structural arrangements provide alluring systems to study the synergism between strongly correlated systems, particularly, those in the structure of (II), and extensive polar intermetallic contacts, which has been inspected by measurements of the magnetic properties, heat capacities and electrical conductivities of both compounds. Gd3Au7Sn3 shows an antiferromagnetic ordering at 13 K, while Y3Au7Sn3 is a Pauli paramagnet and a downward curvature in its electrical resistivity at about 1.9 K points to a superconducting transition. DFT-based band structure calculations on R3Au7Sn3 (R = Y, Gd) account for the results of the conductivity measurements and different spin ordering models of (II) provide conclusive hints about its magnetic structure. As a result, chemical bonding analyses of both compounds indicate that the vast majority of bonding originates from the heteroatomic Au–Gd and Au–Sn interactions, while homoatomic Au–Au bonding is evident within the Au@Au6 clusters.

  5. Six-dimensional quantum dynamics study for the dissociative adsorption of HCl on Au(111) surface

    SciTech Connect (OSTI)

    Liu, Tianhui; Fu, Bina; Zhang, Dong H.

    2013-11-14

    The six-dimensional quantum dynamics calculations for the dissociative chemisorption of HCl on Au(111) are carried out using the time-dependent wave-packet approach, based on an accurate PES which was recently developed by neural network fitting to density functional theory energy points. The influence of vibrational excitation and rotational orientation of HCl on the reactivity is investigated by calculating the exact six-dimensional dissociation probabilities, as well as the four-dimensional fixed-site dissociation probabilities. The vibrational excitation of HCl enhances the reactivity and the helicopter orientation yields higher dissociation probability than the cartwheel orientation. A new interesting site-averaged effect is found for the title molecule-surface system that one can essentially reproduce the six-dimensional dissociation probability by averaging the four-dimensional dissociation probabilities over 25 fixed sites.

  6. Voyager 2 observations of plasmas and flows out to 104 AU

    SciTech Connect (OSTI)

    Richardson, J. D.; Decker, R. B. E-mail: robert.decker@apljhu.edu

    2014-09-10

    Voyager 2 has crossed through 20 AU of the heliosheath; assuming the same heliosheath thickness as at Voyager 1, it is now two-thirds of the way to the heliopause. The plasma data are generally of good quality, although the increasing flow angle of the plasma makes analysis more difficult. The average plasma speed has remained constant but the flow angles have increased to almost 60 in the RT plane and to almost 30 in the RN plane. The average density and thermal speed have been constant since a density increase observed in 2011. Comparison of V2 plasma flows derived from plasma science experiment (PLS) data and Low Energy Charged Particle (LECP) proton anisotropies give good agreement except when heavy ion contributions or non-convective proton anisotropies are observed in the LECP data.

  7. Random telegraph signals by alkanethiol-protected Au nanoparticles in chemically assembled single-electron transistors

    SciTech Connect (OSTI)

    Kano, Shinya; Azuma, Yasuo; Tanaka, Daisuke; Sakamoto, Masanori; Teranishi, Toshiharu; Smith, Luke W.; Smith, Charles G.; Majima, Yutaka

    2013-12-14

    We have studied random telegraph signals (RTSs) in a chemically assembled single-electron transistor (SET) at temperatures as low as 300 mK. The RTSs in the chemically assembled SET were investigated by measuring the sourcedrain current, using a histogram of the RTS dwell time, and calculating the power spectrum density of the drain currenttime characteristics. It was found that the dwell time of the RTS was dependent on the drain voltage of the SET, but was independent of the gate voltage. Considering the spatial structure of the chemically assembled SET, the origin of the RTS is attributed to the trapped charges on an alkanethiol-protected Au nanoparticle positioned near the SET. These results are important as they will help to realize stable chemically assembled SETs in practical applications.

  8. Assembly/Disassembly of DNA-Au Nanoparticles: A Strategy of Intervention

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Lim, I-Im S.; Wang, Lingyan; Chandrachud, Uma; Gal, Susannah; Zhong, Chuan-Jian

    2008-01-01

    This report describes the viability of a strategy for manipulating the assembly/disassembly processes of DNA-Au nanoparticles by molecular intervention. Using the temperature-induced assembly and disassembly processes of DNAs and gold nanoparticles as a model system, the introduction of a molecular recognition probe is demonstrated to lead to the intervention of the assembly/disassembly processes depending on its specific biorecognition. This process can be detected by monitoring the change in the optical properties of gold nanoparticles and their DNA assemblies. Implications of the preliminary results to exploration of the resulting nanostructures for fine-tuning of the interfacial reactivities in DNA-based bioassays and biomaterialmore » engineering are also discussed.« less

  9. Structural and degradation studies of a biocompatible Zn-L-tartrate metal–organic framework

    SciTech Connect (OSTI)

    Palǒić, Ana; Puškarić, Andreas; Mazaj, Matjaž; Žunkoviǒ, Emanuela; Logar, Nataša Zabukovec; Bronić, Josip

    2015-05-15

    New anhydrous Zn-L-tratrate was synthesized under hydrothermal conditions. Crystal structure which was solved by powder X-ray diffraction data from monoclinic unit cell (I{sub 2}, a=11.7557(1), b=9.0319(1), c=5.0750(1), β=91.920(1)) consists of the three-dimensional framework where each Zn atom coordinates four tartrate ligands in distorted octahedral geometry. Due to its biocompatible components, the degradation of material was studied in aqueous media under different pH values (pH=1–7) and in the simulated body fluid (pH=7.4) performed by the measurement of the released Zn{sup 2+} concentrations at thermostatic conditions (37 °C). The results showed that under acidic conditions approximately 60% of Zn{sup 2+} is released from the investigated material after 6 h of degradation process. With the increase of the solution’s pH, the rate of degradation gradually decreases. XRD and SEM analyses indicate that in aqueous media the compound slowly disintegrates and does not undergo hydrolysis process regardless of pH. Biocompatibility of the compound and its controllable rate of degradation even in acid conditions open its potential use in the fields of bio-applications. - Graphical abstract: The degradation kinetics of Zn-L-tar MOF material in aqueous media at different pH conditions. - Highlights: • Anhydrous chiral Zn-L-tratrate was synthesized under hydrothermal conditions. • 3-D framework consists of Zn atoms, each chelating four tartrate ligands. • Degradation of material was studied in aqueous media at different pH values. • The compound disintegrates in controllable manner in aqueous solutions. • The rate compound degradation is increasing with increased acidity of solution.

  10. Characterization of nanocrystalline ZnO:Al films by sol-gel spin coating method

    SciTech Connect (OSTI)

    Gareso, P. L. Rauf, N. Juarlin, E.; Sugianto,; Maddu, A.

    2014-09-25

    Nanocrystalline ZnO films doped with aluminium by sol-gel spin coating method have been investigated using optical transmittance UV-Vis and X-ray diffraction (X-RD) measurements. ZnO films were prepared using zinc acetate dehydrate (Zn(CH{sub 3}COO){sub 2}@@2H{sub 2}O), ethanol, and diethanolamine (DEA) as a starting material, solvent, and stabilizer, respectively. For doped films, AlCl{sub 3} was added to the mixture. The ZnO:Al films were deposited on a transparent conductive oxide (TCO) substrate using spin coating technique at room temperature with a rate of 3000 rpm in 30 sec. The deposited films were annealed at various temperatures from 400C to 600C during 60 minutes. The transmittance UV-Vis measurement results showed that after annealing at 400C, the energy band gap profile of nanocrystalline ZnO:Al film was a blue shift. This indicated that the band gap of ZnO:Al increased after annealing due to the increase of crystalline size. As the annealing temperature increased the bandgap energy was a constant. In addition to this, there was a small oscillation occurring after annealing compared to the asgrown samples. In the case of X-RD measurements, the crystalinity of the films were amorphous before annealing, and after annealing the crystalinity became enhance. Also, X-RD results showed that structure of nanocrystalline ZnO:Al films were hexagonal polycrystalline with lattice parameters are a = 3.290 and c = 5.2531 .

  11. Development of vertically aligned ZnO-nanowires scintillators for high spatial resolution x-ray imaging

    SciTech Connect (OSTI)

    Kobayashi, Masakazu Komori, Jun; Shimidzu, Kaiji; Izaki, Masanobu; Uesugi, Kentaro; Takeuchi, Akihisa; Suzuki, Yoshio

    2015-02-23

    Newly designed scintillator of (0001)-oriented ZnO vertical nanowires (vnws) for X-ray imaging was prepared on a Ga-doped ZnO/soda-lime glass by electrodeposition, and the light emission feature was estimated in a synchrotron radiation facility. The ZnO-vnws scintillator revealed a strong light emission and improved resolution on CMOS image compared with that for the ZnO-layer scintillator, although the light emission performance was deteriorated in comparison to the Lu{sub 3}Al{sub 5}O{sub 12:}Ce{sup 3+}. The light emission property closely related to the nanostructure and the resultant photoluminescence characteristic.

  12. Influence of oxygen on characteristics of Zn(O,S) thin films deposited by RF magnetron sputtering

    SciTech Connect (OSTI)

    Choi, Ji Hyun; Garay, Adrian Adalberto; Hwang, Su Min; Chung, Chee Won

    2015-07-15

    Zn(O,S) thin films were successfully deposited by reactive sputtering using Ar and O{sub 2} gas mixtures at 473 K. X-ray diffraction patterns revealed that the well crystallized Zn(O,S) films were deposited with increasing oxygen concentration in O{sub 2}/Ar, resulting in a shift of the Zn peak of 28.5° to a higher angle, closer to the ZnO peak of 34.4°. Zn(O,S) films were composed of grains agglomerated from small particles, which grew gradually with increasing oxygen concentration. The depth profiles and energy dispersive spectroscopy results of the films indicated that the O/(O+S) ratio increased from 0.04 to 0.81, and all Zn(O,S) films were Zn rich with uniform concentrations of each component. X-ray photoelectron spectroscopy revealed that, as the oxygen concentration increased to 2%, the ZnS films were transformed to Zn(O,S) films via substitution of oxygen for sulfur.

  13. Microstructural and optical properties of nanocrystalline ZnO deposited onto vertically aligned carbon nanotubes by physical vapor deposition

    SciTech Connect (OSTI)

    Borkar, Tushar; Chang, Won Seok; Hwang, Jun Yeon; Shepherd, Nigel D.; Banerjee, Rajarshi

    2012-10-15

    Nanocrystalline ZnO films with thicknesses of 5 nm, 10 nm, 20 nm, and 50 nm were deposited via magnetron sputtering onto the surface of vertically aligned multi-walled carbon nanotubes (MWCNTs). The ZnO/CNTs heterostructures were characterized by scanning electron microscopy, high resolution transmission electron microscopy, and X-ray diffraction studies. No structural degradation of the CNTs was observed and photoluminescence (PL) measurements of the nanostructured ZnO layers show that the optical properties of these films are typical of ZnO deposited at low temperatures. The results indicate that magnetron sputtering is a viable technique for growing heterostructures and depositing functional layers onto CNTs.

  14. The effect of Ce{sup 4+} incorporation on structural, morphological and photocatalytic characters of ZnO nanoparticles

    SciTech Connect (OSTI)

    Kannadasan, N.; Shanmugam, N. Cholan, S.; Sathishkumar, K.; Viruthagiri, G.; Poonguzhali, R.

    2014-11-15

    We report a simple chemical precipitation method for the preparation of undoped and cerium doped ZnO nanocrystals. The concentration of cerium in the products can be controlled in the range of 0.0250.125 mol. The structure and chemical compositions of the products were characterized by X-ray diffraction, X-ray photoelectron spectroscopy; energy dispersive spectrum and Fourier transform infrared spectroscopy. The results demonstrate that Ce{sup 4+} ions were successfully incorporated into the lattice position of Zn{sup 2+} ions in ZnO. The morphology of the products was analyzed by field emission scanning electron microscopy and confirmed by high resolution transmission electron microscope analysis. The optical properties of the products were studied by ultravioletvisible and room temperature photoluminescence measurements. The photoluminescence emission spectra of Ce-doped ZnO showed enhanced visible emissions as a result of 5d ? 4f transition of cerium. In particular, a novel photocatalytic activity of the products was assessed using methylene blue. The obtained result reveals that Ce-doped products show higher reduction efficiency for methylene blue than the undoped ZnO. - Highlights: Nanocrystals of ZnO and ZnO:Ce{sup 4+} were grown. XPS results confirmed the incorporated cerium in tetravalence. PL emission exhibited 5d ? 4f transition on cerium doping. Doped ZnO decolorizes MB faster than undoped ZnO.

  15. The Investigation of Decomposition of Supersaturated Si<Zn> Solid Solution by X-Ray Diffuse Scattering

    SciTech Connect (OSTI)

    Shcherbachev, Kirill; Privezentsev, Vladimir

    2010-04-06

    The results of investigation of microstructure of Zn doped n-type Si by X-ray Diffuse Scattering (XRDS) are presented. Experimental samples were made by a high-temperature Zn diffusion annealing with subsequent quenching and tempering. Reciprocal space maps of XRDS were obtained. They resulted in that crystal lattice of the samples contains spherical MDs of vacancy type and plane shape MDs of interstitial type. The MDs average radius and their type depend on Zn doping level and thermal treatment after Zn diffusion.

  16. Synthesis and characterization of novel WO{sub 3} loaded Ag–ZnO and its photocatalytic activity

    SciTech Connect (OSTI)

    Subash, B.; Krishnakumar, B.; Pandiyan, V.; Swaminathan, M.; Shanthi, M.

    2013-01-15

    Graphical abstract: Display Omitted Highlights: ► A novel WO{sub 3} loaded Ag–ZnO was prepared by a simple solvothermal method. ► ‘Ag’ traps the electron from both ZnO and WO{sub 3} reducing electro–hole recombination. ► WO{sub 3}–Ag–ZnO is more efficient than Ag–ZnO, WO{sub 3}–ZnO, Ag–WO{sub 3} and undoped catalysts. ► WO{sub 3}–Ag–ZnO material will be much useful for the treatment of dye effluents. -- Abstract: A novel WO{sub 3} loaded Ag–ZnO photocatalyst was successfully synthesized by a simple solvothermal method and characterized by X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM) images, energy dispersive spectrum (EDS), diffuse reflectance spectra (DRS), photoluminescence spectra (PL), cyclic voltammetry (CV) and Brunauer–Emmett–Teller (BET) surface area measurements. The photocatalytic activity of WO{sub 3}–Ag–ZnO was investigated for the degradation of RR 120 and RO 4 dyes in aqueous solution using UV-A light. WO{sub 3}–Ag–ZnO is found to be more efficient than Ag–ZnO, WO{sub 3}–ZnO, Ag–WO{sub 3}, commercial ZnO, prepared ZnO, TiO{sub 2}-P25 and TiO{sub 2} (Merck) at neutral pH for the mineralization of dyes. First time we have reported that novel WO{sub 3} loaded Ag–ZnO has been found to be very efficient for two azo dyes removal when compared to commercially available catalyst (Degussa P25, ZnO (Merck) and TiO{sub 2} (Merck)). The mineralization of dyes has been confirmed by chemical oxygen demand (COD) measurements. A mechanism of degradation has been proposed for the higher efficiency of WO{sub 3}–Ag–ZnO.

  17. La-doped ZnO nanoparticles: Simple solution-combusting preparation and applications in the wastewater treatment

    SciTech Connect (OSTI)

    Wu, Tingting; Ni, Yonghong; Ma, Xiang; Hong, Jianming

    2013-11-15

    Graphical abstract: La-doped ZnO nanoparticles have been successfully prepared by a simple solution combustion route and exhibit good adsorption for Cu and Pb ion from water systems. - Highlights: • La-doped ZnO nanoparticles were successfully prepared via a simple solution-combustion route. • The integration of La{sup 3+} ions into ZnO decreased the band-gap of ZnO nanoparticles. • La-doped ZnO nanoparticles could remove more Pb and Cu ions from water resources than undoped ZnO. - Abstract: La-doped ZnO nanoparticles have been successfully synthesized by a simple solution combustion method via employing a mixture of ethanol and ethyleneglycol (v/v = 60/40) as the solvent. Zinc acetate and oxygen gas in the atmosphere were used as zinc and oxygen sources, and La(NO{sub 3}){sub 3} as the doping reagent. The as-obtained product was characterized by means of powder X-ray diffraction, scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray spectrometry and X-ray photoelectron spectroscopy. Experiments showed that La-doped ZnO nanoparticles exhibited the higher capacities for the removal of Pb{sup 2+} and Cu{sup 2+} ions in water resource than undoped ZnO nanoparticles.

  18. Open Charm Yields in d+Au Collisions at sqrt(sNN) = 200 GeV

    SciTech Connect (OSTI)

    Adams, J.; Aggarwal, M.M.; Ahammed, Z.; Amonett, J.; Anderson, B.D.; Arkhipkin, D.; Averichev, G.S.; Badyal, S.K.; Bai, Y.; Balewski, J.; Barannikova, O.; Barnby, L.S.; Baudot, J.; Bekele, S.; Belaga, V.V.; Bellwied, R.; Berger, J.; Bezverkhny, B.I.; Bharadwaj, S.; Bhasin, A.; Bhati, A.K.; Bhatia, V.S.; Bichsel, H.; Billmeier, A.; Bland, L.C.; Blyth, C.O.; Bonner, B.E.; Botje, M.; Boucham, A.; Brandin, A.; Bravar, A.; Bystersky, M.; Cadman, R.V.; Cai, X.Z.; Caines, H.; Calderon de la Barca Sanchez, M.; Castillo, J.; Cebra, D.; Chajecki, Z.; Chaloupka, P.; Chattopadhyay, S.; Chen, H.F.; Chen, Y.; Cheng, J.; Cherney, M.; Chikanian, A.; Christie, W.; Coffin, J.P.; Cormier, T.M.; Cramer, J.G.; Crawford, H.J.; Das, D.; Das, S.; De Moura, M.M.; Derevschikov, A.A.; Didenko, L.; Dietel, T.; Dogra, S.M.; Dong, W.J.; Dong, X.; Draper, J.E.; Du, F.; Dubey, A.K.; Dunin, V.B.; Dunlop, J.C.; Dutta Mazumda, M.R.; Eckardt, V.; Edwards, W.R.; Efimov, L.G.; Emelianov, V.; Engelage, J.; Eppley, G.; Erazmus, B.; Estienne, M.; Fachini, P.; Faivre, J.; Fatemi, R.; Fedorisin, J.; Filimonov, K.; Filip, P.; Finch, E.; Fine, V.; Fisyak, Y.; Fomenko, K.; Fu, J.; Gagliardi, C.A.; Gaillard, L.; Gans, J.; Ganti, M.S.; Gaudichet, L.; Geurts, F.; Ghazikhanian, V.; Ghosh, P.; Gonzalez, J.F.; Grachov, O.; Grebenyuk, O.; Grosnick, D.; Guertin, S.M.; Guo, Y.; Gupta, A.; Gutierrez, T.D.; Hallman, T.J.; Hamed, A.; Hardtke, D.; Harris, J.W.; Heinz, M.; Henry, T.W.; Heppelmann, S.; Hippolyte, B.; Hirsch, A.; Hjort, E.; Hoffmann, G.W.; Huang, H.Z.; Huang, S.L.; Hughes, E.W.; Humanic, T.J.; Igo, G.; Ishihara, A.; Ivanshin, Yu.I.; Jacobs, P.; Jacobs, W.W.; Janik, M.; Jiang, H.; Jones, P.G.; Judd, E.G.; Kabana, S.; Kang, K.; Kaplan, M.; Keane, D.; Khodyrev, V.Yu.; Kiryluk, J.; Kisiel, A.; Kislov, E.M.; Klay, J.; Klein, S.R.; Koetke, D.D.; Kollegger, T.; Kopytine, S.M.; Kotchenda, L.; Kramer, M.; Kravtsov, P.; Kravtsov, V.I.; Krueger, K.; Kuhn, C.; Kulikov, A.I.; Kumar, A.; et al.

    2005-01-07

    Mid-rapidity open charm spectra from direct reconstruction of D{sup 0}({bar D}{sup 0}) {yields} K{sup {-+}} {pi}{sup {+-}} in d+Au collisions and indirect electron/positron measurements via charm semileptonic decays in p+p and d+Au collisions at {radical}s{sub NN} = 200 GeV are reported. The D{sup 0}({bar D}{sup 0}) spectrum covers a transverse momentum (p{sub T}) range of 0.1 < p{sub T} < 3 GeV/c whereas the electron spectra cover a range of 1 < p{sub T} < 4 GeV/c. The electron spectra show approximate binary collision scaling between p+p and d+Au collisions. From these two independent analyses, the differential cross section per nucleon-nucleon binary interaction at mid-rapidity for open charm production from d+Au collisions at RHIC is d{sigma}{sub c{bar c}}{sup NN}/dy = 0.30 {+-} 0.04 (stat.) {+-} 0.09(syst.) mb. The results are compared to theoretical calculations. Implications for charmonium results in A+A collisions are discussed.

  19. Memorandum, AU-1 Clarification on the Drug Testing Custody and Control Form for Department of Energy Contractors

    Broader source: Energy.gov [DOE]

    Memorandum from Matthew Moury, AU-1 clarifying the drug testing custody and control form for DOE contractors. This memo clarifies the correct form for DOE contractors to use when submitting their samples to a drug testing facility in accordance with 10 CFR part 707, Workplace Substance Programs at DOE Sites

  20. Interstaple Dithiol Cross-Linking in Au(25)(SR)(18) Nanomolecules: A Combined Mass Spectrometric and Computational Study

    SciTech Connect (OSTI)

    Jiang, Deen; Dass, Amala; Tschumper, Gregory; Mattern, Daniell; Van Dornshuld, Eric; Kota, Rajesh; Jupally, Vijay

    2011-01-01

    A systematic study of cross-linking chemistry of the Au{sub 25}(SR){sub 18} nanomolecule by dithiols of varying chain length, HS-(CH2)n-SH where n = 2, 3, 4, 5, and 6, is presented here. Monothiolated Au{sub 25} has six [RSAuSRAuSR] staple motifs on its surface, and MALDI mass spectrometry data of the ligand exchanged clusters show that propane (C3) and butane (C4) dithiols have ideal chain lengths for interstaple cross-linking and that up to six C3 or C4 dithiols can be facilely exchanged onto the cluster surface. Propanedithiol predominately exchanges with two monothiols at a time, making cross-linking bridges, while butanedithiol can exchange with either one or two monothiols at a time. The extent of cross-linking can be controlled by the Au{sub 25}(SR){sub 18} to dithiol ratio, the reaction time of ligand exchange, or the addition of a hydrophobic tail to the dithiol. MALDI MS suggests that during ethane (C2) dithiol exchange, two ethanedithiols become connected by a disulfide bond; this result is supported by density functional theory (DFT) prediction of the optimal chain length for the intrastaple coupling. Both optical absorption spectroscopy and DFT computations show that the electronic structure of the Au{sub 25} nanomolecule retains its main features after exchange of up to eight monothiol ligands.

  1. Inter-staple Dithiol Crosslinking in Au25(SR)18 Nanomolecules: A Combined Mass Spectrometric and Computational Study

    SciTech Connect (OSTI)

    Dass, Amala; Jiang, Deen; Jupally, Vijay; Kota, Rajesh; Mattern, Daniell; Tschumper, Gregory; Van Dornshuld, Eric

    2011-01-01

    A systematic study of cross-linking chemistry of the Au{sub 25}(SR){sub 18} nanomolecule by dithiols of varying chain length, HS-(CH{sub 2}){sub n}-SH where n = 2, 3, 4, 5, and 6, is presented here. Monothiolated Au{sub 25} has six [RSAuSRAuSR] staple motifs on its surface, and MALDI mass spectrometry data of the ligand exchanged clusters show that propane (C3) and butane (C4) dithiols have ideal chain lengths for interstaple cross-linking and that up to six C3 or C4 dithiols can be facilely exchanged onto the cluster surface. Propanedithiol predominately exchanges with two monothiols at a time, making cross-linking bridges, while butanedithiol can exchange with either one or two monothiols at a time. The extent of cross-linking can be controlled by the Au{sub 25}(SR){sub 18} to dithiol ratio, the reaction time of ligand exchange, or the addition of a hydrophobic tail to the dithiol. MALDI MS suggests that during ethane (C2) dithiol exchange, two ethanedithiols become connected by a disulfide bond; this result is supported by density functional theory (DFT) prediction of the optimal chain length for the intrastaple coupling. Both optical absorption spectroscopy and DFT computations show that the electronic structure of the Au{sub 25} nanomolecule retains its main features after exchange of up to eight monothiol ligands.

  2. Exploring the activity of a novel Au/TiC(001) model catalyst towards CO and CO2 hydrogenation

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Asara, Gian Giacomo; Ricart, Josep M.; Rodriguez, Jose A.; Illas, Francesc

    2015-02-02

    Small metallic nanoparticles supported on transition metal carbides exhibit an unexpected high activity towards a series of chemical reactions. In particular, the Au/TiC system has proven to be an excellent catalyst for SO2 decomposition, thiophene hydrodesulfurization, O2 and H2 dissociation and the water gas shift reaction. Recent studies have shown that Au/TiC is a very good catalyst for the reverse water–gas shift (CO2 + H2 → CO + H2O) and CO2 hydrogenation to methanol. The present work further expands the range of applicability of this novel type of systems by exploring the catalytic activity of Au/TiC towards the hydrogenation ofmore » CO or CO2 with periodic density functional theory (DFT) calculations on model systems. Hydrogen dissociates easily on Au/TiC but direct hydrogenation of CO to methanol is hindered by very high activation barriers implying that, on this model catalyst, methanol production from CO2 involves the hydrogenation of a HOCO-like intermediate. Thus, when dealing with mixtures of syngas (CO/CO2/H2/H2O), CO could be transformed into CO2 through the water gas shift reaction with subsequent hydrogenation of CO2 to methanol.« less

  3. Copper doping of ZnO crystals by transmutation of {sup 64}Zn to {sup 65}Cu: An electron paramagnetic resonance and gamma spectroscopy study

    SciTech Connect (OSTI)

    Recker, M. C.; McClory, J. W. Holston, M. S.; Golden, E. M.; Giles, N. C.; Halliburton, L. E.

    2014-06-28

    Transmutation of {sup 64}Zn to {sup 65}Cu has been observed in a ZnO crystal irradiated with neutrons. The crystal was characterized with electron paramagnetic resonance (EPR) before and after the irradiation and with gamma spectroscopy after the irradiation. Major features in the gamma spectrum of the neutron-irradiated crystal included the primary 1115.5 keV gamma ray from the {sup 65}Zn decay and the positron annihilation peak at 511 keV. Their presence confirmed the successful transmutation of {sup 64}Zn nuclei to {sup 65}Cu. Additional direct evidence for transmutation was obtained from the EPR of Cu{sup 2+} ions (where {sup 63}Cu and {sup 65}Cu hyperfine lines are easily resolved). A spectrum from isolated Cu{sup 2+} (3d{sup 9}) ions acquired after the neutron irradiation showed only hyperfine lines from {sup 65}Cu nuclei. The absence of {sup 63}Cu lines in this Cu{sup 2+} spectrum left no doubt that the observed {sup 65}Cu signals were due to transmuted {sup 65}Cu nuclei created as a result of the neutron irradiation. Small concentrations of copper, in the form of Cu{sup +}-H complexes, were inadvertently present in our as-grown ZnO crystal. These Cu{sup +}-H complexes are not affected by the neutron irradiation, but they dissociate when a crystal is heated to 900 °C. This behavior allowed EPR to distinguish between the copper initially in the crystal and the copper subsequently produced by the neutron irradiation. In addition to transmutation, a second major effect of the neutron irradiation was the formation of zinc and oxygen vacancies by displacement. These vacancies were observed with EPR.

  4. MAKE SUPER-EARTHS, NOT JUPITERS: ACCRETING NEBULAR GAS ONTO SOLID CORES AT 0.1AU AND BEYOND

    SciTech Connect (OSTI)

    Lee, Eve J.; Chiang, Eugene; Ormel, Chris W. E-mail: echiang@astro.berkeley.edu

    2014-12-20

    Close-in super-Earths having radii 1-4 R {sub ?} may possess hydrogen atmospheres comprising a few percent by mass of their rocky cores. We determine the conditions under which such atmospheres can be accreted by cores from their parent circumstellar disks. Accretion from the nebula is problematic because it is too efficient: we find that 10 M {sub ?} cores embedded in solar metallicity disks tend to undergo runaway gas accretion and explode into Jupiters, irrespective of orbital location. The threat of runaway is especially dire at ?0.1AU, where solids may coagulate on timescales orders of magnitude shorter than gas clearing times; thus nascent atmospheres on close-in orbits are unlikely to be supported against collapse by planetesimal accretion. The time to runaway accretion is well approximated by the cooling time of the atmosphere's innermost convective zone, whose extent is controlled by where H{sub 2} dissociates. Insofar as the temperatures characterizing H{sub 2} dissociation are universal, timescales for core instability tend not to vary with orbital distanceand to be alarmingly short for 10 M {sub ?} cores. Nevertheless, in the thicket of parameter space, we identify two scenarios, not mutually exclusive, that can reproduce the preponderance of percent-by-mass atmospheres for super-Earths at ?0.1AU, while still ensuring the formation of Jupiters at ? 1AU. Scenario (a): planets form in disks with dust-to-gas ratios that range from ?20 solar at 0.1AU to ?2 solar at 5AU. Scenario (b): the final assembly of super-Earth cores from mergers of proto-coresa process that completes quickly at ?0.1AU once begunis delayed by gas dynamical friction until just before disk gas dissipates completely. Both scenarios predict that the occurrence rate for super-Earths versus orbital distance, and the corresponding rate for Jupiters, should trend in opposite directions, as the former population is transformed into the latter: as gas giants become more frequent from

  5. Nanoscale Au-In alloy-oxide core-shell particles as electrocatalysts for efficient hydroquinone detection

    SciTech Connect (OSTI)

    Sutter, E.; Tong, X.; Medina-Plaza, C.; Rodriguez-Mendez, M. L.; Sutter, P.

    2015-10-09

    The presence of hydroquinone (HQ), a phenol ubiquitous in nature and widely used in industry, needs to be monitored because of its toxicity to the environment. Here we demonstrate efficient detection of HQ using simple, fast, and noninvasive electrochemical measurements on indium tin oxide (ITO) electrodes modified with nanoparticles comprising bimetallic Au–In cores and mixed Au–In oxide shells. Whereas bare ITO electrodes show very low activity for the detection of HQ, their modification with Au–In core–shell nanoparticles induces a pronounced shift of the oxidation peak to lower potentials, i.e., facilitated oxidation. The response of the different electrodes was correlated with the initial composition of the bimetallic nanoparticle cores, which in turn determined the amount of Au and In stabilized on the surface of the amorphous Au–In oxide shells available for the electrochemical reaction. While adding core–shell nanostructures with different compositions of the alloy core facilitates the electrocatalytic (reduction-) oxidation of HQ, the activity is highest for particles with AuIn cores (i.e., a Au:In ratio of 1). This optimal system is found to follow a single pathway, the two-electron oxidation of the quinone–hydroquinone couple, which gives rise to high oxidation peaks and is most effective in facilitating the electrode-to-analyte charge transfer and thus detection. The limits of detection (LOD) decreased when increasing the amount of Au exposed on the surface of the amorphous Au–In oxide shells. As a result the LODs were in the range of 10–5 – 10–6 M and were lower than those obtained using bulk Au.

  6. Nanoscale Au-In alloy-oxide core-shell particles as electrocatalysts for efficient hydroquinone detection

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Sutter, E.; Tong, X.; Medina-Plaza, C.; Rodriguez-Mendez, M. L.; Sutter, P.

    2015-10-09

    The presence of hydroquinone (HQ), a phenol ubiquitous in nature and widely used in industry, needs to be monitored because of its toxicity to the environment. Here we demonstrate efficient detection of HQ using simple, fast, and noninvasive electrochemical measurements on indium tin oxide (ITO) electrodes modified with nanoparticles comprising bimetallic Au–In cores and mixed Au–In oxide shells. Whereas bare ITO electrodes show very low activity for the detection of HQ, their modification with Au–In core–shell nanoparticles induces a pronounced shift of the oxidation peak to lower potentials, i.e., facilitated oxidation. The response of the different electrodes was correlated withmore » the initial composition of the bimetallic nanoparticle cores, which in turn determined the amount of Au and In stabilized on the surface of the amorphous Au–In oxide shells available for the electrochemical reaction. While adding core–shell nanostructures with different compositions of the alloy core facilitates the electrocatalytic (reduction-) oxidation of HQ, the activity is highest for particles with AuIn cores (i.e., a Au:In ratio of 1). This optimal system is found to follow a single pathway, the two-electron oxidation of the quinone–hydroquinone couple, which gives rise to high oxidation peaks and is most effective in facilitating the electrode-to-analyte charge transfer and thus detection. The limits of detection (LOD) decreased when increasing the amount of Au exposed on the surface of the amorphous Au–In oxide shells. As a result the LODs were in the range of 10–5 – 10–6 M and were lower than those obtained using bulk Au.« less

  7. Electronegativity calculation of bulk modulus and band gap of ternary ZnO-based alloys

    SciTech Connect (OSTI)

    Li, Keyan; Kang, Congying [State Key Laboratory of Fine Chemicals, School of Chemical Engineering, Dalian University of Technology, Dalian 116024 (China)] [State Key Laboratory of Fine Chemicals, School of Chemical Engineering, Dalian University of Technology, Dalian 116024 (China); Xue, Dongfeng, E-mail: dongfeng@ciac.jl.cn [State Key Laboratory of Fine Chemicals, School of Chemical Engineering, Dalian University of Technology, Dalian 116024 (China) [State Key Laboratory of Fine Chemicals, School of Chemical Engineering, Dalian University of Technology, Dalian 116024 (China); State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (China)

    2012-10-15

    In this work, the bulk moduli and band gaps of M{sub x}Zn{sub 1?x}O (M = Be, Mg, Ca, Cd) alloys in the whole composition range were quantitatively calculated by using the electronegativity-related models for bulk modulus and band gap, respectively. We found that the change trends of bulk modulus and band gap with an increase of M concentration x are same for Be{sub x}Zn{sub 1?x}O and Cd{sub x}Zn{sub 1?x}O, while the change trends are reverse for Mg{sub x}Zn{sub 1?x}O and Ca{sub x}Zn{sub 1?x}O. It was revealed that the bulk modulus is related to the valence electron density of atoms whereas the band gap is strongly influenced by the detailed chemical bonding behaviors of constituent atoms. The current work provides us a useful guide to compositionally design advanced alloy materials with both good mechanical and optoelectronic properties.

  8. Enhanced piezoelectric output voltage and Ohmic behavior in Cr-doped ZnO nanorods

    SciTech Connect (OSTI)

    Sinha, Nidhi; Ray, Geeta; Godara, Sanjay; Gupta, Manoj K.; Kumar, Binay

    2014-11-15

    Highlights: • Low cost highly crystalline Cr-doped ZnO nanorods were synthesized. • Enhancement in dielectric, piezoelectric and ferroelectric properties were observed. • A high output voltage was obtained in AFM. • Cr-doping resulted in enhanced conductivity and better Ohmic behavior in ZnO/Ag contact. - Abstract: Highly crystalline Cr-doped ZnO nanorods (NRs) were synthesized by solution technique. The size distribution was analyzed by high resolution tunneling electron microscope (HRTEM) and particle size analyzer. In atomic force microscope (AFM) studies, peak to peak 8 mV output voltage was obtained on the application of constant normal force of 25 nN. It showed high dielectric constant (980) with phase transition at 69 °C. Polarization vs. electric field (P–E) loops with remnant polarization (6.18 μC/cm{sup 2}) and coercive field (0.96 kV/cm) were obtained. In I–V studies, Cr-doping was found to reduce the rectifying behavior in the Ag/ZnO Schottky contact which is useful for field effect transistor (FET) and solar cell applications. With these excellent properties, Cr-doped ZnO NRs can be used in nanopiezoelectronics, charge storage and ferroelectric applications.

  9. Synthesis and Characterization of Photocatalytic TiO 2 -ZnFe 2 O 4 Nanoparticles

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Srinivasan, Sesha S.; Wade, Jeremy; Stefanakos, Elias K.

    2006-01-01

    A new coprecipimore » tation/hydrolysis synthesis route is used to create a TiO 2 -ZnFe 2 O 4 nanocomposite that is directed towards extending the photoresponse of TiO 2 from UV to visible wavelengths ( > 400   nm ). The effect of TiO 2 's accelerated anatase-rutile phase transformation due to the presence of the coupled ZnFe 2 O 4 narrow-bandgap semiconductor is evaluated. The transformation's dependence on pH, calcinations temperature, particle size, and ZnFe 2 O 4 concentration has been analyzed using XRD, SEM, and UV-visible spectrometry. The requirements for retaining the highly photoactive anatase phase present in a ZnFe 2 O 4 nanocomposite are outlined. The visible-light-activated photocatalytic activity of the TiO 2 -ZnFe 2 O 4 nanocomposites has been compared to an Aldrich TiO 2 reference catalyst, using a solar-simulated photoreactor for the degradation of phenol.« less

  10. Synthesis and Characterization of PhotocatalyticTiO2-ZnFe2O4Nanoparticles

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Srinivasan, Sesha S.; Wade, Jeremy; Stefanakos, Elias K.

    2006-01-01

    A new coprecipitation/hydrolysis synthesis route is used to create aTiO2-ZnFe2O4nanocomposite that is directed towards extending the photoresponse ofTiO2from UV to visible wavelengths (>400?nm). The effect ofTiO2's accelerated anatase-rutile phase transformation due to the presence of the coupledZnFe2O4narrow-bandgap semiconductor is evaluated. The transformation's dependence on pH, calcinations temperature, particle size, andZnFe2O4concentration has been analyzed using XRD, SEM, and UV-visible spectrometry. The requirements for retaining the highly photoactive anatase phase present in aZnFe2O4nanocomposite are outlined. The visible-light-activated photocatalytic activity of theTiO2-ZnFe2O4nanocomposites has been compared to an AldrichTiO2reference catalyst, using a solar-simulated photoreactor formorethe degradation of phenol.less

  11. Electroluminescence from ZnO/Si heterojunctions fabricated by PLD with bias voltage application

    SciTech Connect (OSTI)

    Seno, Yuuki; Konno, Daisuke; Komiyama, Takao; Chonan, Yasunori; Yamaguchi, Hiroyuki; Aoyama, Takashi

    2014-02-21

    Electroluminescence (EL) for ZnO films has been investigated by fabricating n-ZnO/p-Si heterojunctions and changing the VI/II (O/Zn) ratio of the films. In the photoluminescence (PL) spectra, both the near band edge (NBE) emission and the defect-related emission were observed, while in the EL spectra only defect-related emission was observed. The EL spectra were divided into three components: green (550 nm), yellow (618 nm) and red (700 nm) bands; and their intensities were compared. As the VI/II (O/Zn) ratio was increased, the red band emission intensity decreased and the green band emission intensity increased. This implies that the oxygen and the zinc vacancies are related to the red and the green band emissions, respectively. Electron transitions from the conduction band minimum (Ec) to the deep energy levels of these vacancies are suggested to cause the red and the green luminescences while the energy levels of the Zn interstitials are close to the Ec in the band gap and no NBE emission is observed.

  12. Synthesis of Uniformly Distributed Single- and Double-sided Zinc Oxide (ZnO) Nanocombs

    SciTech Connect (OSTI)

    Petford-Long, Amanda K.; Liu, Yuzi; Altintas Yildirim, Ozlem

    2015-11-15

    Uniformly distributed single- and double-sided zinc oxide (ZnO) nanocomb structures have been prepared by a vapor-liquid-solid technique from a mixture of ZnO nanoparticles and graphene nanoplatelets. The ZnO seed nanoparticles were synthesized via a simple precipitation method. The structure of the ZnO nanocombs could easily be controlled by tuning the carrier-gas flow rate during growth. Higher flow rate resulted in the formation of uniformly-distributed single-sided comb structures with nanonail-shaped teeth, as a result of the self-catalysis effect of the catalytically active Zn-terminated polar (0001) surface. Lower gas flow rate was favorable for production of double-sided comb structures with the two sets of teeth at an angle of similar to 110 degrees to each other along the comb ribbon, which was attributed to the formation of a bicrystal nanocomb ribbon. The formation of such a double-sided structure with nanonail-shaped teeth has not previously been reported.

  13. Defects in paramagnetic Co-doped ZnO films studied by transmission electron microscopy

    SciTech Connect (OSTI)

    Kovcs, A.; Duchamp, M.; Boothroyd, C. B.; Dunin-Borkowski, R. E.; Ney, A.; Ney, V.; Galindo, P. L.; Kaspar, T. C.; Chambers, S. A.

    2013-12-28

    We study planar defects in epitaxial Co:ZnO dilute magnetic semiconductor thin films deposited on c-plane sapphire (Al{sub 2}O{sub 3}), as well as the Co:ZnO/Al{sub 2}O{sub 3} interface, using aberration-corrected transmission electron microscopy and electron energy-loss spectroscopy. Co:ZnO samples that were deposited using pulsed laser deposition and reactive magnetron sputtering are both found to contain extrinsic stacking faults, incoherent interface structures, and compositional variations within the first 34 Co:ZnO layers next to the Al{sub 2}O{sub 3} substrate. The stacking fault density is in the range of 10{sup 17} cm{sup ?3}. We also measure the local lattice distortions around the stacking faults. It is shown that despite the relatively high density of planar defects, lattice distortions, and small compositional variation, the Co:ZnO films retain paramagnetic properties.

  14. High-resolution photoluminescence spectroscopy of Sn-doped ZnO single crystals

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Kumar, E. Senthil; Mohammadbeigi, F.; Boatner, Lynn A.; Watkins, S. P.

    2016-03-18

    Here, Group IV donors in ZnO are poorly understood, despite evidence that they are effective n-dopants. We present high-resolution photoluminescence spectroscopy studies of unintentionally doped and Sn doped ZnO single crystals grown by the chemical vapor transport method. Doped samples showed greatly increased emission from the I10 bound exciton transition which was recently proven to be related to the incorporation of Sn impurities based on radio-isotope studies. PL linewidths are exceptionally sharp for these samples, enabling clear identification of several donor species. Temperature dependent PL measurements of the I10 line emission energy and intensity dependence reveal a behavior similar tomore » other shallow donors in ZnO. Ionized donor bound exciton and two electron satellite transitions of the I10 transition are unambiguously identified and yield a donor binding energy of 71 meV. In contrast to recent reports of Ge-related donors in ZnO, the spectroscopic binding energy for the Sn-related donor bound exciton follows a linear relationship with donor binding energy (Haynes rule), confirming the shallow nature of this defect center, which we attribute to a SnZn double donor compensated by an unknown single acceptor.« less

  15. Size and grain morphology dependent magnetic behaviour of Co-doped ZnO

    SciTech Connect (OSTI)

    Vagadia, Megha; Ravalia, Ashish; Khachar, Uma; Solanki, P.S.; Doshi, R.R.; Rayaprol, S.; Kuberkar, D.G.

    2011-11-15

    Highlights: {yields} Structure and magnetic studies on Co-doped ZnO. {yields} Synthesis method dependent comparison of magnetic properties. {yields} Grain size and morphology affect the magnetic properties of Co-doped ZnO. -- Abstract: We have carried out a comparative study of structural, microstructural and magnetic properties of the two sets of Co-doped ZnO samples synthesized using solid state reaction and sol-gel method. Rietveld refinement of the X-ray diffraction data reveals single phase hexagonal wurtzite structure for all the samples, while the tunnelling electron microscopy measurements show the presence of nano-phase in the sol-gel grown Co-doped ZnO samples. It is found that, the microstructure strongly depends on the synthesis method adopted. Samples with higher Co-concentration synthesized by SSR route exhibit antiferromagnetism while SG grown Co-doped ZnO samples exhibit weak ferromagnetic behaviour. Improved magnetic phase in the SG grown samples has been attributed to the grain morphology.

  16. Enhancement of conductivity and transmittance of ZnO films by post hydrogen plasma treatment

    SciTech Connect (OSTI)

    Cai, P. F.; You, J. B.; Zhang, X. W.; Dong, J. J.; Yang, X. L.; Yin, Z. G.; Chen, N. F.

    2009-04-15

    We studied the effects of hydrogen plasma treatment on the electrical and optical properties of ZnO films deposited by radio frequency magnetron sputtering. It is found that the ZnO:H film is highly transparent with the average transmittance of 92% in the visible range. Both carrier concentration and mobility are increased after hydrogen plasma treatment, correspondingly, the resistivity of the ZnO:H films achieves the order of 10{sup -3} OMEGA cm. We suggest that the incorporated hydrogen not only passivates most of the defects and/or acceptors present, but also introduces shallow donor states such as the V{sub O}-H complex and the interstitial hydrogen H{sub i}. Moreover, the annealing data indicate that H{sub i} is unstable in ZnO, while the V{sub O}-H complex remains stable on the whole at 400 deg. C, and the latter diffuses out when the annealing temperature increases to 500 deg. C. These results make ZnO:H more attractive for future applications as transparent conducting electrodes.

  17. Transparent conductive Al-doped ZnO thin films grown at room temperature

    SciTech Connect (OSTI)

    Wang Yuping; Lu Jianguo; Bie Xun; Gong Li; Li Xiang; Song Da; Zhao Xuyang; Ye Wenyi; Ye Zhizhen

    2011-05-15

    Aluminum-doped ZnO (ZnO:Al, AZO) thin films were prepared on glass substrates by dc reactive magnetron sputtering from a Zn-Al alloy target at room temperature. The effects of the Ar-to-O{sub 2} partial pressure ratios on the structural, electrical, and optical properties of AZO films were studied in detail. AZO films grown using 100:4 to 100:8 Ar-to-O{sub 2} ratio result in acceptable quality films with c-axis orientated crystals, uniform grains, 10{sup -3} {Omega} cm resistivity, greater than 10{sup 20} cm{sup -3} electron concentration, and high transmittance, 90%, in the visible region. The lowest resistivity of 4.11x10{sup -3} {Omega} cm was obtained under the Ar-to-O{sub 2} partial pressure ratio of 100:4. A relatively strong UV emission at {approx}3.26 eV was observed in the room-temperature photoluminescence spectrum. X-ray photoelectron spectroscopy analysis confirmed that Al was introduced into ZnO and substitutes for Zn and doped the film n-type.

  18. Nanochannel-Directed Growth of One-Dimensional Multi-Segment Heterojunctions of Metallic Au1-xGex and Semiconducting Ge

    SciTech Connect (OSTI)

    Li, Xiangdong; Meng, Guowen; Qin, Shengyong; Xu, Qiaoling; Chu, Zhaoqin; Zhu, Xiaoguang; Kong, Mingguang; Li, An-Ping

    2012-01-01

    We report on the synthesis of multi-segment nanowire (NW) junctions of Au{sub 1-x}Ge{sub x} and Ge inside the nanochannels of porous anodic aluminum oxide template. The one-dimensional heterostructures are grown with a low-temperature chemical vapor deposition process, assisted by electrodeposited Au nanowires (AuNWs). The Au-catalyzed vapor-liquid-solid growth process occurs simultaneously in multiple locations along the nanochannel, which leads to multi-segment Au{sub 1-x}Ge{sub x}/Ge heterojunctions. The structures of the as-grown hybrid NWs, analyzed by using transmission electron microscopy and energy-dispersive X-ray spectroscopy elemental mapping, show clear compositional modulation with variable modulation period and controllable junction numbers. Remarkably, both GeNW and Au{sub 1-x}Ge{sub x}NW segments are single crystalline with abrupt interfaces and good crystallographic coherences. The electronic and transport properties of individual NW junctions are measured by using a multi-probe scanning tunneling microscope, which confirms the semiconducting nature of Ge segments and the metallic behavior of Au{sub 1-x}Ge{sub x} segments, respectively. The high yield of multiple segment NW junctions of a metal-semiconductor can facilitate the applications in nanoelectronics and optoelectronics that harness multiple functionalities of heterointerfaces.

  19. Thermoelectric Properties of Au- Containing Type-I Clathrates Ba8AuxGa16-3xGe30+2x

    SciTech Connect (OSTI)

    Ye, Zuxin; Cho, Jung Young; Tessema, Misle M.; Salvador, James R.; Waldo, Richard A.; Yang, Jihui; Wang, Hsin; Cai, Wei; Kirkham, Melanie J; Yang, Jiong; Zhang, Wenqing

    2014-01-01

    Type I clathrates, with compositions based on Ba8Ga16Ge30, are a class of promising thermoelectric materials due to their intrinsically low thermal conductivity. It has been demonstrated previously that the thermoelectric performance can be improved by transition metal substitution of the framework atoms. In this study, the effects of Au substitution for Ga/Ge on thermal and electrical transport properties of type I clathrate compounds have been investigated. Polycrystalline samples with a large range of Au content have been synthesized using conventional solid state techniques with the actual compositions of resulting materials approximately following Zintl-Klemm rules. The charge carrier type changes from electrons (n) to holes (p) as the Au content increases. The Seebeck coefficient (S) and power factor (S2/ where is the electrical resistivity) were improved by Au substitution and the resulting overall thermoelectric properties were enhanced by Au substitution with a thermoelectric figure of merit ZT ~ 0.63 at temperature T = 740 K for the composition Ba8Au5.47Ge39.96. The results presented herein show that Au-containing type I clathrates are promising p-type thermoelectric materials for high temperature applications.

  20. Luminescence of CdSe/ZnS quantum dots infiltrated into an opal matrix

    SciTech Connect (OSTI)

    Gruzintsev, A. N. Emelchenko, G. A.; Masalov, V. M.; Yakimov, E. E.; Barthou, C.; Maitre, A.

    2009-02-15

    The effect of the photonic band gap in the photonic crystal, the synthesized SiO{sub 2} opal with embedded CdSe/ZnS quantum dots, on its luminescence in the visible spectral region is studied. It is shown that the position of the photonic band gap in the luminescence and reflectance spectra for the infiltrated opal depends on the diameter of the constituent nanospheres and on the angle of recording the signal. The optimal conditions for embedding the CdSe/ZnS quantum dots from the solution into the opal matrix are determined. It is found that, for the opal-CdSe/ZnS nanocomposites, the emission intensity decreases and the luminescence decay time increases in the spatial directions, in which the spectral positions of the photonic band gap and the luminescence peak of the quantum dots coincide.

  1. A Novel and Functional Single-Layer Sheet of ZnSe

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Zhou, Jia; Sumpter, Bobby G.; Kent, Paul R. C.; Huang, Jingsong

    2014-12-23

    In this Communication, we report a novel singlelayer sheet of ZnSe, with a three-atomic thickness, which demonstrates a strong quantum confinement effect by exhibiting a large blue shift of 2.0 eV in its absorption edge relative to the zinc blende (ZB) bulk phase. Theoretical optical absorbance shows that the largest absorption of this ultrathin single-layer sheet of ZnSe occurs at a wavelength similar to its four-atom-thick doublelayer counterpart but with higher photoabsorption efficiency, suggesting a superior behavior on incident photon-to-current conversion efficiency for solar water splitting, among other potential applications. The results presented herein for ZnSe may be generalized tomore » other group II-VI analogues.« less

  2. Effect of Fe doping concentration on photocatalytic activity of ZnO nanosheets under natural sunlight

    SciTech Connect (OSTI)

    Khokhra, Richa; Kumar, Rajesh

    2015-05-15

    A facile room temperature, aqueous solution-based chemical method has been adopted for large-scale synthesis of Fe doped ZnO nanosheets. The XRD and SEM results reveal the as-synthesized products well crystalline and accumulated by large amount of interweave nanosheets, respectively. Energy dispersive spectroscopy data confirmed Fe doping of the ZnO nanosheets with a varying Fe concentration. The photoluminescence spectrum reveals a continuous suppression of defect related emissions intensity by increasing the concentration of the Fe ion. A photocatalytic activity using these samples under sunlight irradiation in the mineralization of methylene blue dye was investigated. The photocatalytic activity of Fe doped ZnO nanosheets depends upon the presence of surface oxygen vacancies.

  3. Structural analysis of Cr aggregation in ferromagnetic semiconductor (Zn,Cr)Te

    SciTech Connect (OSTI)

    Kobayashi, H.; Yamawaki, K.; Nishio, Y.; Kanazawa, K.; Kuroda, S.; Mitome, M.; Bando, Y.

    2013-12-04

    The Cr aggregation in a ferromagnetic semiconductor (Zn,Cr)Te was studied by performing precise analyses using TEM and XRD of microscopic structure of the Cr-aggregated regions formed in iodine-doped Zn{sub 1?x}Cr{sub x}Te films with a relatively high Cr composition x ? 0.2. It was found that the Cr-aggregated regions are composed of Cr{sub 1??}Te nanocrystals of the hexagonal structure and these hexagonal precipitates are stacked preferentially on the (111)A plane of the zinc-blende (ZB) structure of the host ZnTe crystal with its c-axis nearly parallel to the (111){sub ZB} plane.

  4. Structural and photoluminescence properties of Ce, Dy, Er-doped ZnO nanoparticles

    SciTech Connect (OSTI)

    Jayachandraiah, C.; Kumar, K. Siva; Krishnaiah, G.

    2015-06-24

    Undoped ZnO and rare earth elements (Ce, Dy and Er with 2 at. %) doped nanoparticles were synthesized by wet chemical co-precipitation method at 90°C with Polyvinylpyrrolidone (PVP) as capping agent. The structural, morphological, compositional and photoluminescence studies were performed with X-ray diffraction (XRD), Transmission electron microscopy (TEM), Energy dispersive spectroscopy (EDS), FTIR spectroscopy and Photoluminescence (PL) respectively. XRD results revealed hexagonal wurtzite structure with average particle size around 18 nm - 14 nm and are compatible with TEM results. EDS confirm the incorporation of Ce, Dy and Er elements into the host ZnO matrix and is validated by FTIR analysis. PL studies showed a broad intensive emission peak at 558 nm in all the samples. The intensity for Er- doped ZnO found maximum with additional Er shoulder peaks at 516nm and 538 nm. No Ce, Dy emission centers were found in spectra.

  5. Distinct water activation on polar/non-polar facets of ZnO nanoparticles

    SciTech Connect (OSTI)

    Zhang, He; Sun, Junming; Liu, Changjun; Wang, Yong

    2015-11-01

    ZnO nanoparticles with differing dominant facets were prepared and characterized by a complimentary of techniques such as X-ray diffraction, electron microscopy, temperature programmed desorption of H2O, and Fourier transform infrared spectroscopy analysis of adsorbed D2O. For the first time, water interaction/activation is compared on ZnO polar and non-polar facets. We report that non-polar facets exhibit high activity in water activation, which favors reactions such as ketonization and steam reforming in which dissociated water is involved. The distinct water dissociation on ZnO non-polar facets could be related to its facile formation of oxygen vacancies under realistic reaction conditions.

  6. Homojunction p-n photodiodes based on As-doped single ZnO nanowire

    SciTech Connect (OSTI)

    Cho, H. D.; Zakirov, A. S.; Yuldashev, Sh. U.; Kang, T. W.; Ahn, C. W.; Yeo, Y. K.

    2013-12-04

    Photovoltaic device was successfully grown solely based on the single ZnO p-n homojunction nanowire. The ZnO nanowire p-n diode consists of an as-grown n-type segment and an in-situ arsenic doped p-type segment. This p-n homojunction acts as a good photovoltaic cell, producing a photocurrent almost 45 times larger than the dark current under reverse-biased condition. Our results demonstrate that present ZnO p-n homojunction nanowire can be used as a self-powered ultraviolet photodetector as well as a photovoltaic cell, which can also be used as an ultralow electrical power source for nano-scale electronic, optoelectronic, and medical devices.

  7. ZnO/Ag composite nanorod arrays for surface-plasmon-enhanced emission study

    SciTech Connect (OSTI)

    Pal, Anil Kumar E-mail: d.bharathimohan@gmail.com; Mohan, D. Bharathi E-mail: d.bharathimohan@gmail.com

    2014-04-24

    The surface plasmon resonance enhanced emission through coupling of surface plasmons and exciton band energies is studied in hybrid ZnO/Ag nanostructure. The catalytic growth of ZnO nanorods is controlled in seed mediated growth by altering size distribution of Ag nanoislands. X-ray diffraction shows a predominant (002) crystal plane confirming the preferential growth of ZnO nanorods on as-deposited Ag. Increase of surface roughness in Ag film by post deposition annealing process enhances the light emission due to momentum matching between surface plasmons and excitons as well as a red shift of 32 meV occurs due to multi phonon and phonon-exciton interaction.

  8. On the variations of optical property and electronic structure in heavily Al-doped ZnO films during double-step growth process

    SciTech Connect (OSTI)

    Hu, Q. C.; Ding, K. Zhang, J. Y.; Yan, F. P.; Pan, D. M.; Huang, F.; Chiou, J. W.

    2014-01-13

    We have investigated the variations of optical property and electronic structure in heavily Al-doped ZnO (AZO) films during the growth process, which were formed by first creating Zn vacancies in O{sub 2}-rich atmosphere and second filling the vacancies with Zn atoms in Zn-vapor atmosphere. After the first step, the high-resistance AZO films have the same optical bandgap with nominally undoped ZnO, indicating that negligible variations in the fundamental bandgap happened to the AZO films although Al atom was incorporated into the ZnO lattice. After the second step, once free electrons were brought into the lattice by Zn-filling, the optical transition energy blueshifts due to the band-filling effect. X-ray absorption fine structure measurements suggest that Zn-filling process decreased the unoccupied states of the conduction band, but not raised the conduction band minimum.

  9. Study of difference in interfacial reaction at Fe{sub 3}O{sub 4}/ZnO and ZnO/Fe{sub 3}O{sub 4} heterostructure using synchrotron radiation

    SciTech Connect (OSTI)

    Wadikar, A. D. Master, Ridhi Choudhary, R. J. Phase, D. M.

    2014-04-24

    We have prepared Fe{sub 3}O{sub 4}/ZnO and ZnO/Fe{sub 3}O{sub 4} bilayer structure on p-Si substrate using pulsed laser deposition technique (PLD). X-ray diffraction study revealed (0001) oriented growth of ZnO and (111) oriented growth of Fe{sub 3}O{sub 4} in both the bilayer structure. We observed a change in the density of states near the Fermi level in valence band spectra in case of Fe{sub 3}O{sub 4}/ZnO bilayer when compared to that of ZnO/Fe{sub 3}O{sub 4}. Nonlinear current–voltage (I-V) characteristics were observed in both the samples confirmed that these bilayer structures can be used for spintronic application.

  10. Surface Modification of ZnO Using Triethoxysilane-Based Molecules

    SciTech Connect (OSTI)

    Allen, C. G.; Baker, D. J.; Albin, J. M.; Oertli, H. E.; Gillaspie, D. T.; Olson, D. C.; Furtak, T. E.; Collins, R. T.

    2008-12-01

    Zinc oxide (ZnO) is an important material for hybrid inorganic-organic devices in which the characteristics of the interface can dominate both the structural and electronic properties of the system. These characteristics can be modified through chemical functionalization of the ZnO surface. One of the possible strategies involves covalent bonding of the modifier using silane chemistry. Whereas a significant body of work has been published regarding silane attachments to glass and SiO{sub 2}, there is less information about the efficacy of this method for controlling the surface of metal oxides. Here we report our investigation of molecular layers attached to polycrystalline ZnO through silane bonding, controlled by an amine catalyst. The catalyst enables us to use triethoxysilane precursors and thereby avoid undesirable multilayer formation. The polycrystalline surface is a practical material, grown by sol-gel processing, that is under active exploration for device applications. Our study included terminations with alkyl and phenyl groups. We used water contact angles, infrared spectroscopy, and X-ray photoemission spectroscopy to evaluate the modified surfaces. Alkyltriethoxysilane functionalization of ZnO produced molecular layers with submonolayer coverage and evidence of disorder. Nevertheless, a very stable hydrophobic surface with contact angles approaching 106{sup o} resulted. Phenyltriethoxysilane was found to deposit in a similar manner. The resulting surface, however, exhibited significantly different wetting as a result of the nature of the end group. Molecular layers of this type, with a variety of surface terminations that use the same molecular attachment scheme, should enable interface engineering that optimizes the chemical selectivity of ZnO biosensors or the charge-transfer properties of ZnO-polymer interfaces found in oxide-organic electronics.

  11. Structural- and optical-property characterization of three-dimensional branched ZnO nanospikes

    SciTech Connect (OSTI)

    Chia, M.Y.; Chiu, W.S.; Daud, S.N.H.; Khiew, P.S.; Radiman, S.; Abd-Shukor, R.; Hamid, M.A.A.

    2015-08-15

    Current study reports the synthesis of three-dimensional (3-D) ZnO nanospikes with anomalous optical property, where zinc stearate is adopted as a safe, common and low-cost precursor that undergoes thermal pyrolysis under non-hydrolytic approach. High resolution transmission electron microscope (HRTEM) and scanning electron microscope (SEM) result show that the as-synthesized 3-D ZnO nanospikes are constructed by bundle of nanorods that sprout radially outwards in random orientation. The possible growth mechanism is discussed by referring to the microscopy results. X-ray diffraction (XRD) pattern confirms that the nanospikes are highly crystalline, which existed in hexagonal wurtzite crystal structure. Optical absorption characterization shows that the onset absorption for the nanospikes is slightly red-shifted if compared to commercial ZnO and the corresponding bandgap energy is estimated to be 3.1 eV. The photoluminescene (PL) result of ZnO nanospikes indicate that its optical emission exhibits weak UV emission but very intense visible-light emission that ranged from green- up to red-region. The factors that contributed to the intriguing PL characteristic are discussed. Current finding would offer a versatile synthesis scheme in engineering advanced nanostructures with new design that exhibit congruent optical property. - Graphical abstract: Display Omitted - Highlights: • Pyrolysis of zinc stearate in synthesizing 3-D ZnO nanospikes • ZnO nanospikes possess bundle of nanorods that sprout out from the hexagonal stump • Growth mechanism is deduced to elucidate the morphological evolution from nanobullet to nanospike with branching topology • PL spectrum indicate that the nanospike exhibit prominent visible-light emission that ranged from green- to red-region.

  12. ZnO Nanorod Thermoplastic Polyurethane Nanocomposites: Morphology and Shape Memory Performance

    SciTech Connect (OSTI)

    Koerner, H.; Kelley, J; George, J; Drummy, L; Mirau, P; Bell, N; Hsu, J; Vaia, R

    2009-01-01

    The impact of dispersed alkylthiol-modified ZnO nanorods, as a function of rod aspect ratio and concentration, on the shape memory character of a thermoplastic polyurethane with low hard-segment density (LHS-TPU) is examined relative to the enhanced performance occurring for carbon nanofiber (CNF) dispersion. Solution blending resulted in uniform dispersion within the LHS-TPU of the ZnO nanorods at low volume (weight) fractions (<2.9% v/v (17.75% w/w)). Tensile modulus enhancements were modest though, comparable to values observed for spherical nanofillers. Shape memory characteristics, which in this LHS-TPU result when strain-induced crystallites retard the entropic recovery of the deformed chains, were unchanged for these low volume fraction ZnO nanocomposites. Higher ZnO loadings (12% v/v (50% w/w)) exhibited clustering of ZnO nanorods into a mesh-like structure. Here, tensile modulus and shape recovery characteristics were improved, although not as great as seen for comparable CNF addition. Wide angle X-ray diffraction and NMR revealed that the addition of ZnO nanorods did not impact the inherent strain induced crystallization of the LHS-TPU, which is in contrast to the impact of CNFs and emphasizes the impact of interactions at the polymer-nanoparticle interface. Overall, these findings reinforce the hypothesis that the shape memory properties of polymer nanocomposites are governed by the extent to which nanoparticle addition, via nanoparticle aspect ratio, hierarchical morphology, and interfacial interactions, impacts the molecular mechanism responsible for trapping elastic strain.

  13. Characteristics of ZnO nanostructures produced with [DMIm]BF{sub 4} using ultrasonic radiation

    SciTech Connect (OSTI)

    Rahman, I. B. Abdul; Ayob, M. T. M.; Ishak, I. S.; Mohd Lawi, R. L.; Isahak, W. N. R. W.; Hamid, M. H. N. Abd; Othman, N. K.; Radiman, S.

    2012-11-27

    Great interests in metallic oxides have emerged because of the promising properties of these materials for various applications such as solar cells and sensors. ZnO nanostructures with different morphologies were successfully synthesized from Zn(CH{sub 3}COO){sub 2} Bullet 2H{sub 2}O, NaOH and room temperature ionic liquid (RTIL) 1-decyl-3-methylimidazolium tetrafluoroborate, [DMIm][BF{sub 4}] with ultrasound irradiation. Parameters such as the effect of sonication time (30, 60 and 90 minutes) and Zn(Ac){sub 2} precursor to [DMIm][BF{sub 4}] ratios of 3:5, 5:5 and 5:3 were investigated. X-ray diffraction patterns revealed that the ZnO nanocrystals were hexagonal zincite crystalline in structure. The band gap energies (E{sub g}) were estimated to be 3.35-3.55 eV from the UV-Visible spectrum. The solution with the highest ratio of Zn was analysed with photoluminescence spectroscopy, which exhibited peaks at 362, 403, 468 and 539 nm, at room temperature. The micrographs of field emission scanning electron microscopy and transmission electron microscopy showed that the synthesis products were spherical (30-60 nm), spindle ({approx}10 Multiplication-Sign 70 nm for width Multiplication-Sign length) and whisker-like (100-200 nm), with their dimensions decreasing systematically with increased sonication time. Chemical compositions were approximated at 1:1 for Zn and O, estimated by electron dispersive x-ray spectrum.

  14. Investigation of intrinsic and extrinsic defects effective role on producing intense red emission in ZnO:Eu nanostructures

    SciTech Connect (OSTI)

    Najafi, Mehrdad Haratizadeh, Hamid

    2015-05-15

    Highlights: • Effective role of defects on producing red emission at indirect excitation. • V{sub Zn} and V{sub O} defects have important role on energy transfer. • Mg related defects and Zn{sub i} defects were responsible for blue emission. • Extrinsic and intrinsic defects mediated energy transfer to sensitize Eu{sup 3+} ions. • Decrease of red emission because of diminishing in oxygen vacancy. - Abstract: Europium doped ZnO nanorads and nanosheets were synthesized by hydrothermal method. Effects of Mg doping, morphology and annealing in oxygen ambient on structural and optical properties of ZnO nanostructures were investigated using X-ray diffraction (XRD), particle size analysis (PSA), thermo gravimetric analysis (TGA), differential thermal analysis (DTA), differential thermo gravimetry (DTG), scanning electron microscopy (SEM) and photoluminescence spectroscopy (PL). This study recommends that both of intrinsic and extrinsic defects facilitate energy transfer (ET) from the ZnO host to Eu{sup 3+} ions and consequently have efficient role on producing intense red emission at indirect excitation. The results also showed that annealing process improved the crystal structure of ZnO nanosheets due to decrease of surface defects; however decreased ET and red emission because of diminishing in oxygen vacancy. In addition in ZnO nanorods sample with more surface area in comparison with ZnO nanosheets sample deep level emissions are enhanced.

  15. Study of Even-Even/Odd-Even/Odd-Odd Nuclei in Zn-Ga-Ge Region in the Proton-Neutron IBM/IBFM/IBFFM

    SciTech Connect (OSTI)

    Yoshida, N.; Brant, S.; Zuffi, L.

    2009-08-26

    We study the even-even, odd-even and odd-odd nuclei in the region including Zn-Ga-Ge in the proton-neutron IBM and the models derived from it: IBM2, IBFM2, IBFFM2. We describe {sup 67}Ga, {sup 65}Zn, and {sup 68}Ga by coupling odd particles to a boson core {sup 66}Zn. We also calculate the beta{sup +}-decay rates among {sup 68}Ge, {sup 68}Ga and {sup 68}Zn.

  16. The dependence of ZnO photoluminescence efficiency on excitation conditions and defect densities

    SciTech Connect (OSTI)

    Simmons, Jay G.; Liu, Jie; Foreman, John V.; Everitt, Henry O.

    2013-11-11

    The quantum efficiencies of both the band edge and deep-level defect emission from annealed ZnO powders were measured as a function of excitation fluence and wavelength from a tunable sub-picosecond source. A simple model of excitonic decay reproduces the observed excitation dependence of rate constants and associated trap densities for all radiative and nonradiative processes. The analysis explores how phosphor performance deteriorates as excitation fluence and energy increase, provides an all-optical approach for estimating the number density of defects responsible for deep-level emission, and yields new insights for designing efficient ZnO-based phosphors.

  17. Preparation and characterization of nanodiamond cores coated with a thin Ni-Zn-P alloy film

    SciTech Connect (OSTI)

    Wang Rui; Ye Weichun; Ma Chuanli; Wang Chunming

    2008-02-15

    Nanodiamond cores coated with a thin Ni-Zn-P alloy film were prepared by an electroless deposition method under the conditions of tin chloride sensitization and palladium chloride activation. The prepared materials were analyzed by Fourier transform infrared (FTIR) spectrometry and X-ray diffraction (XRD). The nanostructure of the materials was then characterized by transmission electron microscopy (TEM). The alloy film composition was characterized by Energy Dispersive X-ray (EDX) analysis. The results indicated the approximate composition 49.84%Ni-37.29%Zn-12.88%P was obtained.

  18. CASL - Mixing and non-stoichiometry in Fe-Ni-Cr-Zn-O spinel compounds:

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Density functional theory calculations Mixing and non-stoichiometry in Fe-Ni-Cr-Zn-O spinel compounds: Density functional theory calculations Mixing and non-stoichiometry in Fe-Ni-Cr-Zn-O spinel compounds: Density functional theory calculations D.A. Andersson and C.R. Stanek Materials Science and Technology Division Los Alamos National Laboratory Density functional theory (DFT) calculations have been employed to better understand the thermodynamic properties of AB2O4 (where A=Fe2+, Ni2+ or

  19. Evolution of crystal structure during the initial stages of ZnO atomic layer deposition

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Boichot, R.; Tian, L.; Richard, M. -I.; Crisci, A.; Chaker, A.; Cantelli, V.; Coindeau, S.; Lay, S.; Ouled, T.; Guichet, C.; et al

    2016-01-05

    In this study, a complementary suite of in situ synchrotron X-ray techniques is used to investigate both structural and chemical evolution during ZnO growth by atomic layer deposition. Focusing on the first 10 cycles of growth, we observe that the structure formed during the coalescence stage largely determines the overall microstructure of the film. Furthermore, by comparing ZnO growth on silicon with a native oxide with that on Al2O3(001), we find that even with lattice-mismatched substrates and low deposition temperatures, the crystalline texture of the films depend strongly on the nature of the interfacial bonds.

  20. Passivation of an isoelectronic impurity by atomic hydrogen: The case of ZnTe:O

    SciTech Connect (OSTI)

    Felici, Marco; Polimeni, Antonio; Capizzi, Mario; Nabetani, Y.; Okuno, T.; Aoki, K.; Kato, T.; Matsumoto, T.; Hirai, T.

    2006-03-06

    We investigated the optical properties of ZnTe:O/GaAs before and after atomic hydrogen irradiation. Oxygen incorporation gives rise to energy levels associated with single O atoms, O-O pairs, and O clusters, and to a blueshift of the energy gap of the material with respect to that of pure ZnTe/GaAs. All of these effects disappear progressively after irradiation with H, which also leads to an increase in the tensile strain of the epilayer. These observations provide experimental evidence of H-induced passivation of an isoelectronic impurity in II-VI alloys.

  1. Diameter Control and Photoluminescence of ZnO Nanorods from Trialkylamines

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Andelman, Tamar; Gong, Yinyan; Neumark, Gertrude; O'Brien, Stephen

    2007-01-01

    A novel solution method to control the diameter of ZnO nanorods is reported. Small diameter (2-3 nm) nanorods were synthesized from trihexylamine, and large diameter (50–80 nm) nanorods were synthesized by increasing the alkyl chain length to tridodecylamine. The defect (green) emission of the photoluminescence (PL) spectra of the nanorods varies with diameter, and can thus be controlled by the diameter control. The small ZnO nanorods have strong green emission, while the large diameter nanorods exhibit a remarkably suppressed green band. We show that this observation supports surface oxygen vacancies as the defect that gives rise to the green emission.

  2. Interaction of light with the ZnO surface: Photon induced oxygen breathing, oxygen vacancies, persistent photoconductivity, and persistent photovoltage

    SciTech Connect (OSTI)

    Gurwitz, Ron; Cohen, Rotem; Shalish, Ilan

    2014-01-21

    ZnO surfaces adsorb oxygen in the dark and emit CO{sub 2} when exposed to white light, reminiscent of the lungs of living creatures. We find that this exchange of oxygen with the ambient affects the integrity of the ZnO surface. Thus, it forms a basis for several interesting surface phenomena in ZnO, such as photoconductivity, photovoltage, and gas sensing, and has a role in ZnO electrical conduction. Using x-ray photoelectron spectroscopy on ZnO nanowires, we observed a decomposition of ZnO under white light and formation of oxygen-depleted surface, which explains photoconductivity by the electron donation of oxygen vacancies. Our findings suggest that the observed decomposition of the ZnO lattice may only take place due to photon-induced reduction of ZnO by carbon containing molecules (or carbo-photonic reduction), possibly from the ambient gas, accounting in a consistent way for both the reduced demands on the energy required for decomposition and for the observed emission of lattice oxygen in the form of CO{sub 2}. The formation of oxygen-vacancy rich surface is suggested to induce surface delta doping, causing accumulation of electrons at the surface, which accounts for both the increase in conductivity and the flattening of the energy bands. Using surface photovoltage spectroscopy in ultra high vacuum, we monitored changes in the deep level spectrum. We observe a wide optical transition from a deep acceptor to the conduction band, which energy position coincides with the position of the so called green luminescence in ZnO. This green transition disappears with the formation of surface oxygen vacancies. Since the oxygen vacancies are donors, while the green transition involves surface acceptors, the results suggest that the initial emission of oxygen originates at the defect sites of the latter, thereby eliminating each other. This suggests that the green transition originates at surface Zn vacancy acceptors. Removing an oxygen atom from a Zn vacancy

  3. Minijet Deformation and Charge-independent Two-particleCorrelations on Momentum Subspace (eta,phi) In Au-Au Collisions atsqrt(sNN) = 130 GeV

    SciTech Connect (OSTI)

    Adams, J.; Aggarwal, M.M.; Ahammed, Z.; Amonett, J.; Anderson,B.D.; Arkhipkin, D.; Averichev, G.S.; Badyal, S.K.; Bai, Y.; Balewski,J.; Barannikova, O.; Barnby, L.S.; Baudot, J.; Bekele, S.; Belaga, V.V.; Bellwied, R.; Berger, J.; Bezverkhny, B.I.; Bharadwaj, S.; Bhasin, A.; Bhati, A.K.; Bhatia, V.S; Bichsel, H.; Billmeier, A.; Bland, L.C.; Blyth,C.O.; Bonner, B.E.; Botje, M.; Boucham, A.; Brandin, A.V.; Bravar, A.; Bystersky, M.; Cadman, R.V.; Cai, X.Z.; Caines, H.; Calderon de la BarcaSanchez, M.; Carroll, J.; Castillo, J.; Cebra, D.; Chajecki, Z.; Chaloupka, P.; Chattopadhyay, S.; Chen, H.F.; Chen, Y.; Cheng, J.; Cherney, M.; Chikanian, A.; Christie, W.; Coffin, J.P.; Cormier, T.M.; Cramer, J.G.; Crawford, H.J.; Das, D.; Das, S.; de Moura, M.M.; Derevschikov, A.A.; Didenko, L.; Dietel, T.; Dogra, S.M.; Dong, W.J.; Dong, X.; Draper, J.E.; Du, F.; Dubey, A.K.; Dunin, V.B.; Dunlop, J.C.; Dutta Mazumdar, M.R.; Eckardt, V.; Edwards, W.R.; Efimov, L.G.; Emelianov, V.; Engelage, J.; Eppley, G.; Erazmus, B.; Estienne, M.; Fachini, P.; Faivre, J.; Fatemi, R.; Fedorisin, J.; Filimonov, K.; Filip,P.; Finch, E.; Fine, V.; Fisyak, Y.; Foley, K.J.; Fomenko, K.; Fu, J.; Gagliardi, C.A.; Gans, J.; Ganti, M.S.; Gaudichet, L.; Geurts, F.; Ghazikhanian, V.; Ghosh, P.; Gonzalez, J.E.; Grachov, O.; Grebenyuk, O.; Grosnick, D.; Guertin, S.M.; Guo, Y.; Gupta, A.; Gutierrez, T.D.; Hallman, T.J.; Hamed, A.; Hardtke, D.; Harris, J.W.; Heinz, M.; Henry,T.W.; Hepplemann, S.; Hippolyte, B.; Hirsch, A.; Hjort, E.; Hoffmann,G.W.; Horsley, M.; Huang, H.Z.; Huang, S.L.; Hughes, E.W.; Humanic, T.J.; Igo, G.; Ishihara, A.; Jacobs, P.; Jacobs, W.W.; Janik, M.; Jiang, H.; Jones, P.G.; Judd, E.G.; Kabana, S.; Kang, K.; Kaplan, M.; Keane, D.; Khodyrev, V.Yu.; Kiryluk, J.; Kisiel, A.; Kislov, E.M.; Klay, J.; Klein,S.R.; Klyachko, A.; Koetke, D.D.; Kollegger, T.; Kopytine, M.; Kotchenda,L.; Kramer, M.; Kravtsov, P.; Kravtsov, V.I.; Krueger, K.; Kuhn, C.; et al.

    2004-11-04

    We present first measurements of charge-independent correlations on momentum-space difference variables {eta}{sub 1}-{eta}{sub 2} (pseudorapidity) and {phi}{sub 1}-{phi}{sub 2} (azimuth) for charged primary hadrons with transverse momentum within 0.15 {le} p{sub t} {le} 2 GeV/c and |{eta}| {le} 1.3 from Au-Au collisions at {radical}s{sub NN} = 130 GeV. We observe strong charge-independent correlations associated with minijets and elliptic flow. The width of the minijet peak on {eta}{sub 1}-{eta}{sub 2} increases by a factor 2.3 from peripheral to central collisions, suggesting strong coupling of partons to a longitudinally-expanding colored medium. New methods of jet analysis introduced here reveal nonperturbative medium effects in heavy ion collisions.

  4. Effect of microwave irradiation on the resistance of Au-TiB{sub x}-Ge-Au-n-n{sup +}-n{sup ++}-GaAs(InP) ohmic contacts

    SciTech Connect (OSTI)

    Belyaev, A. E.; Sachenko, A. V.; Boltovets, N. S. Ivanov, V. N.; Konakova, R. V. Kudryk, Ya. Ya.; Matveeva, L. A.; Milenin, V. V.; Novitskii, S. V.; Sheremet, V. N.

    2012-04-15

    Temperature dependences of the contact resistivity {rho}{sub c} of Au-TiB{sub x}-Ge-Au-n-n{sup +}-n{sup ++}(GaAs)-InP ohmic contacts before and after short-term (10 s) microwave treatment have been studied both experimentally and theoretically. It is shown that {rho}{sub c} can decrease after microwave treatment in the entire temperature range of {rho}{sub c} measurements (100-400 K). Good agreement between the theoretical and experimental {rho}{sub c}(T) curves is attained and interpreted on the assumption that the dislocation density in the semiconductor near-surface region is varied as a result of microwave radiation.

  5. Wide-bandgap high-mobility ZnO thin-film transistors produced at room temperature

    SciTech Connect (OSTI)

    Fortunato, Elvira M.C.; Barquinha, Pedro M.C.; Pimentel, Ana C.M.B.G.; Goncalves, Alexandra M.F.; Marques, Antonio J.S.; Martins, Rodrigo F.P.; Pereira, Luis M.N.

    2004-09-27

    We report high-performance ZnO thin-film transistor (ZnO-TFT) fabricated by rf magnetron sputtering at room temperature with a bottom gate configuration. The ZnO-TFT operates in the enhancement mode with a threshold voltage of 19 V, a saturation mobility of 27 cm{sup 2}/V s, a gate voltage swing of 1.39 V/decade and an on/off ratio of 3x10{sup 5}. The ZnO-TFT presents an average optical transmission (including the glass substrate) of 80% in the visible part of the spectrum. The combination of transparency, high mobility, and room-temperature processing makes the ZnO-TFT a very promising low-cost optoelectronic device for the next generation of invisible and flexible electronics.

  6. Significant in-medium {eta}{sup '} mass reduction in {radical}(s{sub NN}) = 200 GeV Au+Au collisions at the BNL Relativistic Heavy Ion Collider

    SciTech Connect (OSTI)

    Vertesi, R.; Sziklai, J.; Csoergo, T.

    2011-05-15

    In high-energy heavy ion collisions a hot and dense medium is formed, where the U{sub A}(1) or chiral symmetry may temporarily be restored. As a consequence, the mass of the {eta}{sup '}(958) mesons may be reduced to its quark model value, and the abundance of {eta}{sup '} mesons at low p{sub T} may be enhanced by more than a factor of 10. The intercept parameter {lambda}{sub *} of the charged pion Bose Einstein correlations provides a sensitive observable of the possibly enhanced {eta}{sup '} abundance. We have analyzed {lambda}{sub *}(m{sub T}) data from {radical}(s{sub N{sub N}})=200 GeV central Au+Au reactions measured at the BNL Relativistic Heavy Ion Collider (RHIC), using extensive Monte Carlo simulations based on six popular models for hadronic multiplicities. Based on the combined STAR and PHENIX data set, and on various systematic investigations of resonance multiplicities and model parameters, we conclude that in {radical}(s{sub N{sub N}})=200 GeV central Au+Au reactions the mass of the {eta}{sup '} meson is reduced by {Delta}m{sub {eta}}{sup '*}>200 MeV, at the 99.9% confidence level in the considered model class. Such a significant {eta}{sup '} mass modification may indicate the restoration of the U{sub A}(1) symmetry in a hot and dense hadronic matter and the return of the ninth ''prodigal'' Goldstone boson. A similar analysis of NA44 S+Pb data at top CERN Super Proton Synchroton (SPS) energies showed no significant in-medium {eta}{sup '} mass modification.

  7. Six-dimensional quantum dynamics study for the dissociative adsorption of DCl on Au(111) surface

    SciTech Connect (OSTI)

    Liu, Tianhui; Fu, Bina, E-mail: bina@dicp.ac.cn, E-mail: zhangdh@dicp.ac.cn; Zhang, Dong H., E-mail: bina@dicp.ac.cn, E-mail: zhangdh@dicp.ac.cn [State Key Laboratory of Molecular Reaction Dynamics and Center for Theoretical Computational Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023 (China)

    2014-04-14

    We carried out six-dimensional quantum dynamics calculations for the dissociative adsorption of deuterium chloride (DCl) on Au(111) surface using the initial state-selected time-dependent wave packet approach. The four-dimensional dissociation probabilities are also obtained with the center of mass of DCl fixed at various sites. These calculations were all performed based on an accurate potential energy surface recently constructed by neural network fitting to density function theory energy points. The origin of the extremely small dissociation probability for DCl/HCl (v=0, j=0) fixed at the top site compared to other fixed sites is elucidated in this study. The influence of vibrational excitation and rotational orientation of DCl on the reactivity was investigated by calculating six-dimensional dissociation probabilities. The vibrational excitation of DCl enhances the reactivity substantially and the helicopter orientation yields higher dissociation probability than the cartwheel orientation. The site-averaged dissociation probability over 25 fixed sites obtained from four-dimensional quantum dynamics calculations can accurately reproduce the six-dimensional dissociation probability.

  8. Electronic structure and conductivity of nanocomposite metal (Au,Ag,Cu,Mo)-containing amorphous carbon films

    SciTech Connect (OSTI)

    Endrino, Jose L.; Horwat, David; Gago, Raul; Andersson, Joakim; Liu, Y.S.; Guo, Jinghua; Anders, Andre

    2008-05-14

    In this work, we study the influence of the incorporation of different metals (Me = Au, Ag, Cu, Mo) on the electronic structure of amorphous carbon (a-C:Me) films. The films were produced at room temperature using a novel pulsed dual-cathode arc deposition technique. Compositional analysis was performed with secondary neutral mass spectroscopy whereas X-ray diffraction was used to identify the formation of metal nanoclusters in the carbon matrix. The metal content incorporated in the nanocomposite films induces a drastic increase in the conductivity, in parallel with a decrease in the band gap corrected from Urbach energy. The electronic structure as a function of the Me content has been monitored by x-ray absorption near edge structure (XANES) at the C K-edge. XANES showed that the C host matrix has a dominant graphitic character and that it is not affected significantly by the incorporation of metal impurities, except for the case of Mo, where the modifications in the lineshape spectra indicated the formation of a carbide phase. Subtle modifications of the spectral lineshape are discussed in terms of nanocomposite formation.

  9. Understanding the Kondo resonance in the d-CoPc/Au(111) adsorption system

    SciTech Connect (OSTI)

    Wang, Yu; Zheng, Xiao Li, Bin; Yang, Jinlong

    2014-08-28

    By combining the density functional theory (DFT) and a hierarchical equations of motion (HEOM) approach, we investigate the Kondo phenomena in a composite system consisting of a dehydrogenated cobalt phthalocyanine molecule (d-CoPc) adsorbed on an Au(111) surface. DFT calculations are performed to determine the ground-state geometric and electronic structures of the adsorption system. It is found that the singly occupied d{sub z{sup 2}} orbital of Co forms a localized spin, which could be screened by the substrate conduction electrons. This screening leads to the prominent Kondo features as observed in the scanning tunneling microscopy experiments. We then employ the HEOM approach to characterize the Kondo correlations of the adsorption system. The calculated temperature-dependent differential conductance spectra and the predicted Kondo temperature agree well with the experiments, and the universal Kondo scaling behavior is correctly reproduced. This work thus provides important insights into the relevant experiments, and it also highlights the applicability of the combined DFT+HEOM approach to the studies of strongly correlated condensed matter systems.

  10. Au-iClick mirrors the mechanism of copper catalyzed azide–alkyne cycloaddition (CuAAC)

    SciTech Connect (OSTI)

    Powers, Andrew R.; Ghiviriga, Ion; Abboud, Khalil A.; Veige, Adam S.

    2015-07-20

    This report outlines the investigation of the iClick mechanism between gold(I)-azides and gold(I)-acetylides to yield digold triazolates. Isolation of digold triazolate complexes offer compelling support for the role of two copper(I) ions in CuAAC. In addition, a kinetic investigation reveals the reaction is first order in both Au(I)-N3 and Au(I)-C≡C-R equivalent to C-R, thus second order overall. A Hammett plot with a ρ = 1.02(5) signifies electron-withdrawing groups accelerate the cycloaddition by facilitating the coordination of the second gold ion in a π-complex. Rate inhibition by the addition of free triphenylphosphine to the reaction indicates that ligand dissociation is a prerequisite for the reaction. The mechanistic conclusions mirror those proposed for the CuAAC reaction.

  11. Au-iClick mirrors the mechanism of copper catalyzed azide–alkyne cycloaddition (CuAAC)

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Powers, Andrew R.; Ghiviriga, Ion; Abboud, Khalil A.; Veige, Adam S.

    2015-07-20

    This report outlines the investigation of the iClick mechanism between gold(I)-azides and gold(I)-acetylides to yield digold triazolates. Isolation of digold triazolate complexes offer compelling support for the role of two copper(I) ions in CuAAC. In addition, a kinetic investigation reveals the reaction is first order in both Au(I)-N3 and Au(I)-C≡C-R equivalent to C-R, thus second order overall. A Hammett plot with a ρ = 1.02(5) signifies electron-withdrawing groups accelerate the cycloaddition by facilitating the coordination of the second gold ion in a π-complex. Rate inhibition by the addition of free triphenylphosphine to the reaction indicates that ligand dissociation is amore » prerequisite for the reaction. The mechanistic conclusions mirror those proposed for the CuAAC reaction.« less

  12. Self-organization of S adatoms on Au(111): √3R30° rows at low coverage

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Walen, Holly; Liu, Da -Jiang; Oh, Junepyo; Lim, Hyunseob; Evans, J. W.; Kim, Yousoo; Thiel, P. A.

    2015-07-06

    Using scanning tunneling microscopy, we observe an adlayer structure that is dominated by short rows of S atoms, on unreconstructed regions of a Au(111) surface. This structure forms upon adsorption of low S coverage (less than 0.1 monolayer) on a fully reconstructed cleansurface at 300 K, then cooling to 5 K for observation. The rows adopt one of three orientations that are rotated by 30° from the close-packed directions of the Au(111) substrate, and adjacent S atoms in the rows are separated by √3 times the surface lattice constant, a. Monte Carlo simulations are performed on lattice-gas models, we derivedmore » using a limited cluster expansion based on density functional theory energetics. Furthermore, models which include long-range pairwise interactions (extending to 5a), plus selected trio interactions, successfully reproduce the linear rows of S atoms at reasonable temperatures.« less

  13. Surface plasmon dispersion engineering via double-metallic AU/AG layers for nitride light-emitting diodes

    DOE Patents [OSTI]

    Tansu, Nelson; Zhao, Hongping; Zhang, Jing; Liu, Guangyu

    2014-04-01

    A double-metallic deposition process is used whereby adjacent layers of different metals are deposited on a substrate. The surface plasmon frequency of a base layer of a first metal is tuned by the surface plasmon frequency of a second layer of a second metal formed thereon. The amount of tuning is dependent upon the thickness of the metallic layers, and thus tuning can be achieved by varying the thicknesses of one or both of the metallic layers. In a preferred embodiment directed to enhanced LED technology in the green spectrum regime, a double-metallic Au/Ag layer comprising a base layer of gold (Au) followed by a second layer of silver (Ag) formed thereon is deposited on top of InGaN/GaN quantum wells (QWs) on a sapphire/GaN substrate.

  14. Magnetic switching behaviors of orbital states with different magnetic quantum numbers in Au/Fe/MgO multilayer system

    SciTech Connect (OSTI)

    Suzuki, Kosuke Takubo, Shota; Kato, Tadashi; Yamazoe, Masatoshi; Hoshi, Kazushi; Sakurai, Hiroshi; Homma, Yoshiya; Itou, Masayoshi; Sakurai, Yoshiharu

    2014-08-18

    A spin specific magnetic hysteresis (SSMH) curve and an orbital specific magnetic hysteresis (OSMH) curve are obtained for Fe/Au/Fe/MgO multilayers by magnetic Compton scattering and SQUID magnetometer measurements. The SSMH curve with each contribution of magnetic quantum number |m| = 0, 1, and 2 states is obtained by decomposition analyses of magnetic Compton profiles. Residual magnetization is observed for the SSMH curve with magnetic quantum number |m| = 0, 2 and the OSMH curve. Although the SQUID magnetometer measurements do not show perpendicular magnetic anisotropy (PMA) in the present Fe/Au/Fe/MgO multilayer film, the SSMH curve with magnetic quantum number |m| = 0, 2 and OSMH curve show switching behaviors of PMA.

  15. Degradation mechanisms of Ti/Al/Ni/Au-based Ohmic contacts on AlGaN/GaN HEMTs

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Hwang, Ya-Hsi; Ahn, Shihyun; Dong, Chen; Zhu, Weidi; Kim, Byung-Jae; Le, Lingcong; Ren, Fan; Lind, Aaron G.; Dahl, James; Jones, Kevin S.; et al

    2015-04-27

    We investigated the degradation mechanism of Ti/Al/Ni/Au-based Ohmic metallization on AlGaN/GaN high electron mobility transistors upon exposure to buffer oxide etchant (BOE). The major effect of BOE on the Ohmic metal was an increase of sheet resistance from 2.89 to 3.69 Ω/ₜafter 3 min BOE treatment. The alloyed Ohmic metallization consisted 3–5 μm Ni-Al alloy islands surrounded by Au-Al alloy-rings. The morphology of both the islands and ring areas became flatter after BOE etching. Lastly, we used energy dispersive x-ray analysis and Auger electron microscopy to analyze the compositions and metal distributions in the metal alloys prior to and aftermore » BOE exposure.« less

  16. Conductance and spin-filter effects of oxygen-incorporated Au, Cu, and Fe single-atom chains

    SciTech Connect (OSTI)

    Zheng, Xiaolong; Xie, Yi-Qun Ye, Xiang; Ke, San-Huang

    2015-01-28

    We studied the spin-polarized electron transport in oxygen-incorporated Au, Cu, and Fe single-atom chains (SACs) by first-principles calculations. We first investigated the mechanism responsible for the low conductance (<1G{sub 0}) of the Au and Cu SACs in an oxygen environment reported in recent experiments. We found that for the Au SACs, the low conductance plateau around 0.6G{sub 0} can be attributed to a distorted chain doped with a single oxygen atom, while the 0.1G{sub 0} conductance comes from a linear chain incorporated with an oxygen molecule and is caused by an antibonding state formed by oxygen's occupied frontier orbital with d{sub z} orbitals of adjacent Au atoms. For the Cu SACs, the conductance about 0.3G{sub 0} is ascribed to a special configuration that contains Cu and O atoms in an alternating sequence. This exhibits an even-odd conductance oscillation with an amplitude of ∼0.1G{sub 0}. In contrast, for the alternating Fe-O SACs, conductance overall decreases with an increase in O atoms and it approaches nearly zero for the chain with more than four O atoms. While the Cu-O SACs behave as perfect spin filters for one spin channel due to the half metallic nature, the Fe-O SACs can serve as perfect spin filters for two spin channels depending on the polarity of the applied gate voltage.

  17. The effects of fabrication and annealing on the structure and hydrogen permeation of Pd-Au binary alloy membranes

    SciTech Connect (OSTI)

    Gade, Sabina K; Payzant, E Andrew; Park, Helen J; Thoen, Paul M; Way, J. Douglas

    2009-01-01

    The addition of gold to palladium membranes produces many desirable effects for hydrogen purification, including improved tolerance of sulfur compounds, reduction in hydride phase formation, and, for certain compositions, improved hydrogen permeability. The focus of this work is to determine if sequential plating can be used to produce self-supported alloy membranes with equivalent properties to membranes produced by conventional metallurgical techniques such as cold-working. Sequential electroplating and electroless plating were used to produce freestanding planar Pd-Au membranes with Au contents ranging from 0 to 20 wt%, consisting of Au layers on both sides of a pure Pd core. Membranes were characterized by single-gas permeation measurements, scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM/EDS), and high temperature, controlled-atmosphere XRD (HTXRD). Sequentially plated foils tested without any prior annealing had significantly lower H2 permeabilities than either measured or literature values for homogeneous foils of equivalent composition. This effect appears to be due to the formation of stable gold-enriched surface layers. Pretreatment of membranes to 1023 K created membranes with hydrogen permeabilities equivalent to literature values, despite the fact that trace amounts of surface gold remained detectable with XRD.

  18. Φ meson production in d+Au collisions at √sNN = 200 GeV

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Adare, A.

    2015-10-19

    The PHENIX Collaboration has measured Φ meson production in d+Au collisions at √sNN=200 GeV using the dimuon and dielectron decay channels. The Φ meson is measured in the forward (backward) d-going (Au-going) direction, 1.2 T) range from 1–7 GeV/c and at midrapidity |y|T range below 7 GeV/c. The Φ meson invariant yields and nuclear-modification factors as a function of pT, rapidity, and centrality are reported. An enhancement of Φ meson production is observed in the Au-going direction, while suppression is seen in the d-going direction,more »and no modification is observed at midrapidity relative to the yield in p+p collisions scaled by the number of binary collisions. As a result, similar behavior was previously observed for inclusive charged hadrons and open heavy flavor, indicating similar cold-nuclear-matter effects.« less

  19. Organogold oligomers: Exploiting iClick and aurophilic cluster formation to prepare solution stable Au4 repeating units

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Yang, Xi; Wang, Shanshan; Ghiviriga, Ion; Abboud, Khalil A.; Veige, Adam S.

    2015-05-19

    A novel synthetic method to create gold based metallo–oligomers/polymers via the combination of inorganic click (iClick) with intermolecular aurophilic interactions is demonstrated. Complexes [PEt3Au]4(μ-N3C2C6H5) (1) and [PPhMe2Au]43C2C6H5) (2) and {[PEt3Au]4[(μ-N3C2)2-9,9-dihexyl-9H-fluorene]}n (8) have been synthesized via iClick. The tetranuclear structures of 1 and 2, induced by aurophilic bonding, are confirmed in the solid state through single crystal X-ray diffraction experiments and in solution via variable temperature NMR spectroscopy. The extended 1D structure of 8 is constructed by aurophilic induced self-assembly. 1H DOSY NMR analysis reveals that the aurophilic bonds in 1, 2, and 8 are retained in the solution phase. Themore » degree of polymerization within complex 8 is temperature and concentration dependent, as determined by 1H DOSY NMR. The complex 8 is a rare example of a solution stable higher ordered structure linked by aurophilic interactions.« less

  20. Heteroepitaxial growth of Pt and Au thin films on MgO single crystals by bias-assisted sputtering

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Tolstova, Yulia; Omelchenko, Stefan T.; Shing, Amanda M.; Atwater, Harry A.

    2016-03-17

    The crystallographic orientation of a metal affects its surface energy and structure, and has profound implications for surface chemical reactions and interface engineering, which are important in areas ranging from optoelectronic device fabrication to catalysis. However, it can be very difficult and expensive to manufacture, orient, and cut single crystal metals along different crystallographic orientations, especially in the case of precious metals. One approach is to grow thin metal films epitaxially on dielectric substrates. In this work, we report on growth of Pt and Au films on MgO single crystal substrates of (100) and (110) surface orientation for use asmore » epitaxial templates for thin film photovoltaic devices. We develop bias-assisted sputtering for deposition of oriented Pt and Au films with sub-nanometer roughness. We show that biasing the substrate decreases the substrate temperature necessary to achieve epitaxial orientation, with temperature reduction from 600 to 350 °C for Au, and from 750 to 550 °C for Pt, without use of transition metal seed layers. Additionally, this temperature can be further reduced by reducing the growth rate. Biased deposition with varying substrate bias power and working pressure also enables control of the film morphology and surface roughness.« less