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1

High-harmonic XUV source for time- and angle-resolved photoemission spectroscopy  

Science Conference Proceedings (OSTI)

We present a laser-based apparatus for visible pump/XUV probe time- and angle-resolved photoemission spectroscopy (TRARPES) utilizing high-harmonic generation from a noble gas. Femtosecond temporal resolution for each selected harmonic is achieved by using a time-delay-compensated monochromator (TCM). The source has been used to obtain photoemission spectra from insulators (UO{sub 2}) and ultrafast pump/probe processes in semiconductors (GaAs).

Dakovski, Georgi L [Los Alamos National Laboratory; Li, Yinwan [Los Alamos National Laboratory; Durakiewicz, Tomasz [Los Alamos National Laboratory; Rodriguez, George [Los Alamos National Laboratory

2009-01-01T23:59:59.000Z

2

Study of High Temperature Superconductors with Angle-Resolved Photoemission Spectroscopy  

Science Conference Proceedings (OSTI)

The Angle Resolved Photoemission Spectroscopy (ARPES) recently emerged as a powerful tool for the study of highly correlated materials. This thesis describes the new generation of ARPES experiment, based on the third generation synchrotron radiation source and utilizing very high resolution electron energy and momentum analyzer. This new setup is used to study the physics of high temperature superconductors. New results on the Fermi surfaces, dispersions, scattering rate and superconducting gap in high temperature superconductors are presented.

Dunn, Lisa

2003-05-13T23:59:59.000Z

3

Electronic Band Dispersion Of CeAg{sub 2}Ge{sub 2} Studied Using Angle Resolved Photoemission Spectroscopy  

Science Conference Proceedings (OSTI)

Angle resolved photoelectron spectroscopy has been used to determine the electronic band dispersion of CeAg{sub 2}Ge{sub 2} single crystal along the {Gamma}-Z direction. Normal emission photoelectron spectra for photon energy from 21 eV to 35 eV were used to obtain the band mapping. Four photoemission features are observed to show the dispersion. The experimental spectra have been interpreted with the help of calculations based on full potential linear augmented plane wave method using density functional theory. The bands that show dispersion along the {Gamma}-Z direction are mainly related to the Ce 4f states and the hybridized Ag 4d with Ge 4p states.

Banik, Soma; Chakrabarti, Aparna; Deb, S. K. [Raja Ramanna Centre for Advanced Technology, Indore 452013 (India); Jha, S. N. [Spectroscopy Division, Bhabha Atomic Research Center, Mumbai 400085 (India); Thamizhavel, A. [Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai 400005 (India)

2011-07-15T23:59:59.000Z

4

Intrinsic ultrathin topological insulators grown via molecular beam epitaxy characterized by in-situ angle resolved photoemission spectroscopy  

Science Conference Proceedings (OSTI)

We demonstrate the capability of growing high quality ultrathin (10 or fewer quintuple layers) films of the topological insulators Bi{sub 2}Se{sub 3} and Bi{sub 2}Te{sub 3} using molecular beam epitaxy. Unlike previous growth techniques, which often pin the Fermi energy in the conduction band for ultrathin samples, our samples remain intrinsic bulk insulators. We characterize these films using in-situ angle resolved photoemission spectroscopy, which is a direct probe of bandstructure, and ex-situ atomic force microscopy. We find that the conduction band lies above the Fermi energy, indicating bulk insulating behavior with only the surface states crossing the Fermi energy. The use of a thermal cracker allows for more stoichiometric flux rates during growth, while still creating intrinsically doped films, paving the way for future improvements in growth of topological insulators.

Lee, J. J.; Vishik, I. M.; Ma, Y.; Shen, Z. X. [Department of Applied Physics, Stanford University, Stanford, California 94305 (United States); Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025 (United States); Geballe Laboratory for Advanced Materials, Department of Applied Physics, Stanford University, Stanford, California 94305 (United States); Schmitt, F. T.; Moore, R. G. [Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025 (United States); Geballe Laboratory for Advanced Materials, Department of Applied Physics, Stanford University, Stanford, California 94305 (United States)

2012-07-02T23:59:59.000Z

5

Development of soft x-ray time-resolved photoemission spectroscopy system with a two-dimensional angle-resolved time-of-flight analyzer at SPring-8 BL07LSU  

Science Conference Proceedings (OSTI)

We have developed a soft x-ray time-resolved photoemission spectroscopy system using synchrotron radiation (SR) at SPring-8 BL07LSU and an ultrashort pulse laser system. Two-dimensional angle-resolved measurements were performed with a time-of-flight-type analyzer. The photoemission spectroscopy system is synchronized to light pulses of SR and laser using a time control unit. The performance of the instrument is demonstrated by mapping the band structure of a Si(111) crystal over the surface Brillouin zones and observing relaxation of the surface photo-voltage effect using the pump (laser) and probe (SR) method.

Ogawa, Manami; Yamamoto, Susumu; Nakamura, Fumitaka; Yukawa, Ryu; Fukushima, Akiko; Harasawa, Ayumi; Kakizaki, Akito; Matsuda, Iwao [Institute for Solid State Physics, University of Tokyo, 5-1-5 Kashiwanoha, Chiba 277-8581 (Japan); Kousa, Yuka; Kondoh, Hiroshi [Department of Chemistry, Keio University, Yokohama 223-8522 (Japan); Tanaka, Yoshihito [RIKEN/SPring-8 Center, 1-1-1, Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5148 (Japan)

2012-02-15T23:59:59.000Z

6

Doping Dependence of the $(\\pi,\\pi)$ Shadow Band in La-Based Cuprates Studied by Angle-Resolved Photoemission Spectroscopy  

SciTech Connect

The ({pi},{pi}) shadow band (SB) in La-based cuprate family (La214) was studied by angle-resolved photoemission spectroscopy (ARPES) over a wide doping range from x = 0.01 to x = 0.25. Unlike the well-studied case of the Bi-based cuprate family, an overall strong, monotonic doping dependence of the SB intensity at the Fermi level (E{sub F}) was observed. In contrast to a previous report for the presence of the SB only close to x = 1/8, we found it exists in a wide doping range, associated with a doping-independent ({pi},{pi}) wave vector but strongly doping-dependent intensity: It is the strongest at x {approx} 0.03 and systematically diminishes as the doping increases until it becomes negligible in the overdoped regime. This SB with the observed doping dependence of intensity can in principle be caused by the antiferromagnetic fluctuations or a particular form of low-temperature orthorhombic lattice distortion known to persist up to x {approx} 0.21 in the system, with both being weakened with increasing doping. However, a detailed binding energy dependent analysis of the SB at x = 0.07 does not appear to support the former interpretation, leaving the latter as a more plausible candidate, despite a challenge in quantitatively linking the doping dependences of the SB intensity and the magnitude of the lattice distortion. Our finding highlights the necessity of a careful and global consideration of the inherent structural complications for correctly understanding the cuprate Fermiology and its microscopic implication.

Shen, Z. X.

2011-08-15T23:59:59.000Z

7

Zn-impurity effects on quasiparticle scattering in La2-xSrxCuO4 studied by angle-resolved photoemission spectroscopy  

SciTech Connect

Angle-resolved photoemission measurements were performed on Zn-doped La{sub 2-x}Sr{sub x}CuO{sub 4} to investigate the effects of Zn impurities on the low-energy electronic structure. The Zn-impurity-induced increase in the quasiparticle width in momentum distribution curves (MDCs) is approximately isotropic on the entire Fermi surface and energy independent near the Fermi level (EF). The increase in the MDC width is consistent with the increase in the residual resistivity due to the Zn impurities if we assume the carrier number to be 1-x for x=0.17 and the Zn impurity to be a potential scatterer close to the unitarity limit. For x=0.03, the residual resistivity is found to be higher than that expected from the MDC width, and the effects of antiferromagnetic fluctuations induced around the Zn impurities are discussed. The leading edges of the spectra near ({pi},0) for x=0.17 are shifted toward higher energies relative to E{sub F} with Zn substitution, indicating a reduction in the superconducting gap.

Yoshida, T.

2010-02-24T23:59:59.000Z

8

An ultrafast angle-resolved photoemission apparatus for measuring complex materials  

Science Conference Proceedings (OSTI)

We present technical specifications for a high resolution time- and angle-resolved photoemission spectroscopy setup based on a hemispherical electron analyzer and cavity-dumped solid state Ti:sapphire laser used to generate pump and probe beams, respectively, at 1.48 and 5.93 eV. The pulse repetition rate can be tuned from 209 Hz to 54.3 MHz. Under typical operating settings the system has an overall energy resolution of 23 meV, an overall momentum resolution of 0.003 A{sup -1}, and an overall time resolution of 310 fs. We illustrate the system capabilities with representative data on the cuprate superconductor Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8+{delta}}. The descriptions and analyses presented here will inform new developments in ultrafast electron spectroscopy.

Smallwood, Christopher L.; Lanzara, Alessandra [Department of Physics, University of California, Berkeley, California 94720 (United States); Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Jozwiak, Christopher [Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Zhang Wentao [Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)

2012-12-15T23:59:59.000Z

9

A New Spin on Photoemission Spectroscopy  

SciTech Connect

The electronic spin degree of freedom is of general fundamental importance to all matter. Understanding its complex roles and behavior in the solid state, particularly in highly correlated and magnetic materials, has grown increasingly desirable as technology demands advanced devices and materials based on ever stricter comprehension and control of the electron spin. However, direct and efficient spin dependent probes of electronic structure are currently lacking. Angle Resolved Photoemission Spectroscopy (ARPES) has become one of the most successful experimental tools for elucidating solid state electronic structures, bolstered bycontinual breakthroughs in efficient instrumentation. In contrast, spin-resolved photoemission spectroscopy has lagged behind due to a lack of similar instrumental advances. The power of photoemission spectroscopy and the pertinence of electronic spin in the current research climate combine to make breakthroughs in Spin and Angle Resolved Photoemission Spectroscopy (SARPES) a high priority . This thesis details the development of a unique instrument for efficient SARPES and represents a radical departure from conventional methods. A custom designed spin polarimeter based on low energy exchange scattering is developed, with projected efficiency gains of two orders of magnitude over current state-of-the-art polarimeters. For energy analysis, the popular hemispherical analyzer is eschewed for a custom Time-of-Flight (TOF) analyzer offering an additional order of magnitude gain in efficiency. The combined instrument signifies the breakthrough needed to perform the high resolution SARPES experiments necessary for untangling the complex spin-dependent electronic structures central to today?s condensed matter physics.

Advanced Light Source; Jozwiak, Chris

2008-12-18T23:59:59.000Z

10

Extracting the Spectral Function of the Cuprates By a Full Two-Dimensional Analysis: Angle-Resolved Photoemission Spectra of Bi(2)Sr(2)CuO(6)  

SciTech Connect

Recently, angle-resolved photoemission spectroscopy (ARPES) has revealed a dispersion anomaly at high binding energy near 0.3--0.5eV in various families of the high-temperature superconductors. For further studies of this anomaly, we present a new two-dimensional fitting scheme and apply it to high-statistics ARPES data of the strongly overdoped Bi{sub 2}Sr{sub 2}CuO{sub 6} cuprate superconductor. The procedure allows us to extract the self-energy in an extended energy and momentum range. It is found that the spectral function of Bi{sub 2}Sr{sub 2}CuO{sub 6} can be parametrized using a small set of tight-binding parameters and a weakly momentum-dependent self-energy up to 0.7eV in binding energy and over the entire first Brillouin zone. Moreover, the analysis gives an estimate of the momentum dependence of the matrix element, a quantity, which is often neglected in ARPES analyses.

Meevasana, W.; Baumberger, F.; Tanaka, K.; Schmitt, F.; Dunkel, W.R.; Lu, D.H.; Mo, S.-K.; Eisaki, H.; Shen, Z.-X.

2009-05-26T23:59:59.000Z

11

Extracting the spectral function of the cuprates by a full two-dimensional analysis: Angle-resolved photoemission spectra of Bi2Sr2CuO6  

SciTech Connect

Recently, angle-resolved photoemission spectroscopy (ARPES) has revealed a dispersion anomaly at high binding energy near 0.3-0.5 eV in various families of the high-temperature superconductors. For further studies of this anomaly we present a new two-dimensional fitting-scheme and apply it to high-statistics ARPES data of the strongly-overdoped Bi{sub 2}Sr{sub 2}CuO{sub 6} cuprate superconductor. The procedure allows us to extract the self-energy in an extended energy and momentum range. It is found that the spectral function of Bi{sub 2}Sr{sub 2}CuO{sub 6} can be parameterized using a small set of tight-binding parameters and a weakly-momentum-dependent self-energy up to 0.7 eV in binding energy and over the entire first Brillouin zone. Moreover the analysis gives an estimate of the momentum dependence of the matrix element, a quantity, which is often neglected in ARPES analyses.

Meevasana, W.

2010-04-30T23:59:59.000Z

12

Characterization of geometrical factors for quantitative angle-resolved photoelectron spectroscopy  

SciTech Connect

For conventional angle-resolved x-ray photoelectron spectroscopy (ARXPS), the area under the core-level peaks depends mainly on the in-depth distribution of chemical species at the top surface of a specimen. But the x-ray photoelectron spectroscopy (XPS) intensity is also affected by tool-related geometrical factors such as the shape of the x-ray beam, the spectrometer analysis volume, and the manipulator rotation axis. Data analysis is therefore typically based on normalization with respect to the signal from the substrate. Here, we present an original method to perform quantitative ARXPS without normalization, involving evaluation of these geometrical factors. The method is illustrated for a multiprobe XPS system using a methodology based on a specific software (XPSGeometry{sup Registered-Sign }), but is a general process that can be adapted to all types of XPS equipment, even those not specifically designed for ARXPS. In that case, this method enables bringing the sample as close as possible to the manipulator axis of rotation in order to perform automatic acquisitions.

Martinez, Eugenie; Herrera-Gomez, Alberto; Allain, Mickael; Renault, Olivier; Faure, Alain; Chabli, Amal; Bertin, Francois [CEA, LETI, MINATEC Campus, 17 rue des Martyrs, F-38054 Grenoble Cedex 9 (France); CINVESTAV-Queretaro, Libramiento Norponiente 2000, Real de Juriquilla, Queretaro, 76000 (Mexico); CEA, LETI, MINATEC Campus, 17 rue des Martyrs, F-38054 Grenoble Cedex 9 (France)

2012-07-15T23:59:59.000Z

13

Angle-resolved scattering spectroscopy of explosives using an external cavity quantum cascade laser  

Science Conference Proceedings (OSTI)

Investigation of angle-resolved scattering from solid explosives residues on a car door for non-contact sensing geometries. Illumination with a mid-infrared external cavity quantum cascade laser tuning between 7 and 8 microns was detected both with a sensitive single point detector and a hyperspectral imaging camera. Spectral scattering phenomena were discussed and possibilities for hyperspectral imaging at large scattering angles were outlined.

Suter, Jonathan D.; Bernacki, Bruce E.; Phillips, Mark C.

2012-04-01T23:59:59.000Z

14

High-resolution angle-resolved photoemission studies of high Tc superconductor Bi sub 2 Sr sub 2 CaCu sub 2 O sub 8  

SciTech Connect

An angle-resolved photoemission study of the normal and superconducting states in Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8} was performed. Measurements in the normal state show bands dispersing through the Fermi level from at least 350 meV below E{sub F}. The Fermi level crossings are consistant with local-density band calculation, including a point calculated to be of Bi-O character. Additional measurements were made where bands crossed the Fermi level between 100 and 250K, along with measurements on an adjacent Pt foil. The Fermi edges of both materials agree to within the noise. Below the Fermi level, the spectra show correlation effects on the form of an increased effective mass. The shape of the spectra can be explained by a lifetime-broadened photohole and secondary electrons. The effective inverse photohole lifetime is linear in energy. A superconducting gap has been measured at a number of points where there is density at the Fermi level in the normal state. By proper modeling, a gap of 24 meV was obtained for all these points, including points of Cu-O and Bi-O character respectively, according to band calculation. The lack of gap anisotropy in the basal plane suggests that pinning in this material is not d-wave pairing.

Liu, Rong.

1990-09-21T23:59:59.000Z

15

Electronic Properties of Iron Arsenic High Temperature Superconductors Revealed by Angle Resolved Photoemission Spectroscopy (ARPES)  

Science Conference Proceedings (OSTI)

We present an overview of the electronic properties of iron arsenic high temperature superconductors with emphasis on low energy band dispersion, Fermi surface and superconducting gap. ARPES data is compared with full-potential linearized plane wave (FLAPW) calculations. We focus on single layer NdFe-AsO{sub 0.9}F{sub 0.1} (R1111) and two layer Ba{sub 1-x}K{sub x}Fe{sub 2}As{sub 2} (B122) compounds. We find general similarities between experimental data and calculations in terms of character of Fermi surface pockets, and overall band dispersion. We also find a number of differences in details of the shape and size of the Fermi surfaces as well as the exact energy location of the bands, which indicate that magnetic interaction and ordering significantly affects the electronic properties of these materials. The Fermi surface consists of several hole pockets centered at {tau} and electron pockets located in zone corners. The size and shape of the Fermi surface changes significantly with doping. Emergence of a coherent peak below the critical temperature T{sub c} and diminished spectral weight at the chemical potential above T{sub c} closely resembles the spectral characteristics of the cuprates, however the nodeless superconducting gap clearly excludes the possibility of dwave order parameter. Instead it points to s-wave or extended s-wave symmetry of the order parameter.

Valla, T.; Liu, C.; Kondo, T.; Palczewski, A.D.; Samolyuk, G.D.; Lee, Y.; Tillman, M.E.; Ni, N.; Muna, E.D.; Gordon, R.; Santander-Syro, A.F.; Bud’ko, S.L.; McChesney, J.L.; Rotenberg, E.; Fedorov, A.V.; Copie, O.; Tanatar, M.A.; Martin, C.; Harmon, B.N.; Canfield, P.C.; Prozorov, R.; Schmalian, J.; Kaminski, A.

2009-06-15T23:59:59.000Z

16

Exploring Competing Orders in the High-Tc Cuprate Phase Diagram Using Angle Resolved Photoemission Spectroscopy  

E-Print Network (OSTI)

the competing order. Does this order fundamentally compete,see in Section 4.3, this order does not appear to correspondunit cells on the order 10? A, ARPES does not have good bulk

Garcia, Daniel Robert

2010-01-01T23:59:59.000Z

17

Electronic-Structure-Driven Magnetic and Structure Transitions in Superconducting NaFeAs Single Crystals Measured by Angle-Resolved Photoemission Spectroscopy  

E-Print Network (OSTI)

Hiroshima Synchrotron Radiation Center and Graduate School of Science, Hiroshima University, Hiroshima 739

Hu, Jiangping

18

THE DETERMINATION OF ELECTRONIC STATES IN CRYSTALLINE SEMICONDUCTORS AND METALS BY ANGLE RESOLVED PHOTOEMISSION  

E-Print Network (OSTI)

177 (1979). J.A.Knapp and G.J.Lapeyre, II Nuovo Cim. 39B,and H.Kasper, II Nuovo Cim. 38B, R.J.Elliot, Phys. Rev. 9j5,and G.J.Lapeyre, II Nuovo Cim. 39B, 693 (1977). W.E.Spicer,

Mills, K.A.

2010-01-01T23:59:59.000Z

19

Widespread spin polarization effects in photoemission from topological insulators  

SciTech Connect

High-resolution spin- and angle-resolved photoemission spectroscopy (spin-ARPES) was performed on the three-dimensional topological insulator Bi{sub 2}Se{sub 3} using a recently developed high-efficiency spectrometer. The topological surface state's helical spin structure is observed, in agreement with theoretical prediction. Spin textures of both chiralities, at energies above and below the Dirac point, are observed, and the spin structure is found to persist at room temperature. The measurements reveal additional unexpected spin polarization effects, which also originate from the spin-orbit interaction, but are well differentiated from topological physics by contrasting momentum and photon energy and polarization dependencies. These observations demonstrate significant deviations of photoelectron and quasiparticle spin polarizations. Our findings illustrate the inherent complexity of spin-resolved ARPES and demonstrate key considerations for interpreting experimental results.

Jozwiak, C.; Chen, Y. L.; Fedorov, A. V.; Analytis, J. G.; Rotundu, C. R.; Schmid, A. K.; Denlinger, J. D.; Chuang, Y.-D.; Lee, D.-H.; Fisher, I. R.; Birgeneau, R. J.; Shen, Z.-X.; Hussain, Z.; Lanzara, A.

2011-06-22T23:59:59.000Z

20

Widespread spin polarization effects in photoemission from topological insulators  

SciTech Connect

High-resolution spin- and angle-resolved photoemission spectroscopy (spin-ARPES) was performed on the three-dimensional topological insulator Bi{sub 2}Se{sub 3} using a recently developed high-efficiency spectrometer. The topological surface state's helical spin structure is observed, in agreement with theoretical prediction. Spin textures of both chiralities, at energies above and below the Dirac point, are observed, and the spin structure is found to persist at room temperature. The measurements reveal additional unexpected spin polarization effects, which also originate from the spin-orbit interaction, but are well differentiated from topological physics by contrasting momentum and photon energy and polarization dependencies. These observations demonstrate significant deviations of photoelectron and quasiparticle spin polarizations. Our findings illustrate the inherent complexity of spin-resolved ARPES and demonstrate key considerations for interpreting experimental results.

Jozwiak, C.; Chen, Y. L.; Fedorov, A. V.; Analytis, J. G.; Rotundu, C. R.; Schmid, A. K.; Denlinger, J. D.; Chuang, Y.-D.; Lee, D.-H.; Fisher, I. R.; Birgeneau, R. J.; Shen, Z.-X.; Hussain, Z.; Lanzara, A.

2011-06-22T23:59:59.000Z

Note: This page contains sample records for the topic "angle-resolved photoemission spectroscopy" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


21

Pu electronic structure and photoelectron spectroscopy  

Science Conference Proceedings (OSTI)

The electronic structure of PuCoGa{sub 5}, Pu metal, and PuO{sub 2} is explored using photoelectron spectroscopy. Ground state electronic properties are inferred from temperature dependent photoemission near the Fermi energy for Pu metal. Angle-resolved photoemission details the energy vs. crystaJ momentum landscape near the Fermi energy for PuCoGa{sub 5} which shows significant dispersion in the quasiparticle peak near the Fermi energy. For the Mott insulators AnO{sub 2}(An = U, Pu) the photoemission results are compared against hybrid functional calculations and the model prediction of a cross over from ionic to covalent bonding is found to be reasonable.

Joyce, John J [Los Alamos National Laboratory; Durakiewicz, Tomasz [Los Alamos National Laboratory; Graham, Kevin S [Los Alamos National Laboratory; Bauer, Eric D [Los Alamos National Laboratory; Moore, David P [Los Alamos National Laboratory; Mitchell, Jeremy N [Los Alamos National Laboratory; Kennison, John A [Los Alamos National Laboratory; Martin, Richard L [Los Alamos National Laboratory; Roy, Lindsay E [Los Alamos National Laboratory; Scuseria, G. E. [RICE UNIV

2010-01-01T23:59:59.000Z

22

Soft x-ray absorption and photoemission spectroscopy study of superoxide KO2 J.-S. Kang,* D. H. Kim, and J. H. Hwang  

E-Print Network (OSTI)

Soft x-ray absorption and photoemission spectroscopy study of superoxide KO2 J.-S. Kang,* D. H. Kim of superoxide KO2 was investigated by employing soft x-ray absorption spectros- copy XAS and core cooling, O2 - molecular bond axes seem to tilt to have a lower crystal monoclinic symme- try. By lowering

Min, Byung Il

23

Stable five axes cryogenic photoemission manipulator without a differentially pumped rotary feedthrough  

Science Conference Proceedings (OSTI)

We report on the design and construction of an ultrahigh vacuum compatible cryogenic manipulator for angle resolved photoemission spectroscopy. Unlike designs that have been used so far, our design allows five motions (three translational and two angular) without a differentially pumped rotary feedthrough. The design greatly reduces the sample motion upon rotation, which is crucial in automatic data acquisition over a large area in the momentum space. The constructed manipulator shows smooth motions in vacuum and the lowest temperature it could reach is about 8 K at the sample position. Angular reproducibilities are found to be about 0.02 deg. for both of the angular motions. The wobbling motion from the rotation around the vertical rotation axis is found to be virtually nonexistent (less than 0.1 mm)

Kim, Bum Joon; Kim, Hyeong-Do; Cho, Deok-Yong; Kim, Myongjin; Oh, S.-J.; Kim, Changyoung [School of Physics and Center for Strongly Correlated Materials Research, Seoul National University, Seoul 151-742 (Korea, Republic of); Pohang Accelerator Laboratory, Pohang University of Science and Technology, Pohang 790-784 (Korea, Republic of); School of Physics and Center for Strongly Correlated Materials Research, Seoul National University, Seoul 151-742 (Korea, Republic of); Pohang Accelerator Laboratory, Pohang University of Science and Technology, Pohang 790-784 (Korea, Republic of); School of Physics and Center for Strongly Correlated Materials Research, Seoul National University, Seoul 151-742 (Korea, Republic of); Institute of Physics and Applied Physics, Yonsei University, Seoul 120-749 (Korea, Republic of)

2005-06-15T23:59:59.000Z

24

Efficient spin resolved spectroscopy observation machine at Hiroshima Synchrotron Radiation Center  

SciTech Connect

Highly efficient spin- and angle-resolved photoelectron spectrometer named ESPRESSO (Efficient SPin REsolved SpectroScopy Observation) machine has been developed at the beamline BL-9B in Hiroshima Synchrotron Radiation Center. Combination of high-resolution hemispherical electron analyzer and the high-efficient spin detector based on very low energy electron diffraction by the ferromagnetic target makes the high-energy resolution and angular resolution compatible with spin- and angle-resolved photoemission (SARPES) measurement. 7.5 meV in energy and {+-}0.18 deg. in angular resolution have been achieved with spin resolution. The ESPRESSO machine, combination of quick energy-band dispersion measurement and Fermi surface mapping by two-dimensional electron detector for the spin integrated ARPES and the high-efficient spin analysis by the efficient spin detector realizes the comprehensive investigation of spin electronic structure of materials.

Okuda, Taichi; Miyamaoto, Koji; Namatame, Hirofumi [Hiroshima Synchrotron Radiation Center (HSRC), Hiroshima University, 2-313 Kagamiyama, Higashi-Hiroshima 739-0046 (Japan); Miyahara, Hirokazu; Kuroda, Kenta; Kimura, Akio [Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima 739-8526 (Japan); Taniguchi, Masaki [Hiroshima Synchrotron Radiation Center (HSRC), Hiroshima University, 2-313 Kagamiyama, Higashi-Hiroshima 739-0046 (Japan); Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima 739-8526 (Japan)

2011-10-15T23:59:59.000Z

25

Conduction-band electronic states of YbInCu{sub 4} studied by photoemission and soft x-ray absorption spectroscopies  

SciTech Connect

We have studied conduction-band (CB) electronic states of a typical valence-transition compound YbInCu{sub 4} by means of temperature-dependent hard x-ray photoemission spectroscopy (HX-PES) of the Cu 2p{sub 3/2} and In 3d{sub 5/2} core states taken at h{nu}=5.95 keV, soft x-ray absorption spectroscopy (XAS) of the Cu 2p{sub 3/2} core absorption region around h{nu}{approx}935 eV, and soft x-ray photoemission spectroscopy (SX-PES) of the valence band at the Cu 2p{sub 3/2} absorption edge of h{nu}=933.0 eV. With decreasing temperature below the valence transition at T{sub V}=42 K, we have found that (1) the Cu 2p{sub 3/2} and In 3d{sub 5/2} peaks in the HX-PES spectra exhibit the energy shift toward the lower binding-energy side by {approx}40 and {approx}30 meV, respectively, (2) an energy position of the Cu 2p{sub 3/2} main absorption peak in the XAS spectrum is shifted toward higher photon-energy side by {approx}100 meV, with an appearance of a shoulder structure below the Cu 2p{sub 3/2} main absorption peak, and (3) an intensity of the Cu L{sub 3}VV Auger spectrum is abruptly enhanced. These experimental results suggest that the Fermi level of the CB-derived density of states is shifted toward the lower binding-energy side. We have described the valence transition in YbInCu{sub 4} in terms of the charge transfer from the CB to Yb 4f states.

Utsumi, Yuki; Kurihara, Hidenao; Maso, Hiroyuki; Tobimatsu, Komei [Graduate School of Science, Hiroshima University, Higashi-Hiroshima 739-8526 (Japan); Sato, Hitoshi; Shimada, Kenya; Namatame, Hirofumi [Hiroshima Synchrotron Radiation Center, Hiroshima University, Higashi-Hiroshima 739-0046 (Japan); Hiraoka, Koichi [Graduate School of Science and Engineering, Ehime University, Matsuyama 790-8577 (Japan); Kojima, Kenichi [Graduate School of Integrated Arts and Sciences, Hiroshima University, Higashi-Hiroshima 739-8521 (Japan); Ohkochi, Takuo; Fujimori, Shin-ichi; Takeda, Yukiharu; Saitoh, Yuji [Synchrotron Radiation Research Center, Japan Atomic Energy Agency, Hyogo 679-5148 (Japan); Mimura, Kojiro [Graduate School of Engineering, Osaka Prefecture University, Sakai 599-8531 (Japan); Ueda, Shigenori; Yamashita, Yoshiyuki; Yoshikawa, Hideki; Kobayashi, Keisuke [NIMS Beamline Station at SPring-8, National Institute for Materials Science, Hyogo 679-5148 (Japan); Oguchi, Tamio [ISIR, Osaka University, Ibaraki 567-0047 (Japan); Taniguchi, Masaki [Graduate School of Science, Hiroshima University, Higashi-Hiroshima 739-8526 (Japan); Hiroshima Synchrotron Radiation Center, Hiroshima University, Higashi-Hiroshima 739-0046 (Japan)

2011-09-15T23:59:59.000Z

26

NIST: Ultraviolet Photoemission Electron Microscopy  

Science Conference Proceedings (OSTI)

Ultraviolet Photoemission Electron Microscopy. Summary: Ultraviolet photoemission electron microscopy is used to study ...

2012-11-19T23:59:59.000Z

27

Spin polarization and magnetic dichroism in core-level photoemission from ferromagnets  

Science Conference Proceedings (OSTI)

In this thesis we present a theoretical investigation of angle- and spin-resolved core-level photoemission from ferromagnetic Fe and Ni. We also consider magneto-dichroic effects due to reversal of the photon helicity or reversal of the sample magnetization direction. In chapter 1, we provide a brief outline of the history of photoemission, and show how it has played an important role in the development of modern physics. We then review the basic elements of the theory of core-level photoemission, and discuss the validity of the some of the commonly-used approximations. In chapter 2, we present a one-electron theory to calculate spin- and angle-resolved photoemission spectra for an arbitrary photon polarization. The Hamiltonian includes both spin-orbit and exchange interactions. As test cases for the theory, we calculate the spin polarization and magnetic dichroism for the Fe 2p core level, and find that agreement with experiment is very good.

Menchero, J.G. [Univ. of California, Berkeley, CA (United States). Dept. of Physics]|[Lawrence Berkeley National Lab., CA (United States)

1997-05-01T23:59:59.000Z

28

Angle-resolved photoemission study of the evolution of band structure and charge density wave properties in RTe3 (R= Y, La, Ce, Sm, Gd, Tb and Dy)  

SciTech Connect

We present a detailed ARPES investigation of the RTe{sub 3} family, which sets this system as an ideal 'textbook' example for the formation of a nesting driven Charge Density Wave (CDW). This family indeed exhibits the full range of phenomena that can be associated to CDW instabilities, from the opening of large gaps on the best nested parts of Fermi Surface (FS) (up to 0.4eV), to the existence of residual metallic pockets. ARPES is the best suited technique to characterize these features, thanks to its unique ability to resolve the electronic structure in k-space. An additional advantage of RTe{sub 3} is that the band structure can be very accurately described by a simple 2D tight-binding (TB) model, which allows one to understand and easily reproduce many characteristics of the CDW. In this paper, we first establish the main features of the electronic structure, by comparing our ARPES measurements with Linear Muffin-Tin Orbital band calculations. We use this to define the validity and limits of the TB model. We then present a complete description of the CDW properties and, for the first time, of their strong evolution as a function of R. Using simple models, we are able to reproduce perfectly the evolution of gaps in k-space, the evolution of the CDW wave vector with R and the shape of the residual metallic pockets. Finally, we give an estimation of the CDW interaction parameters and find that the change in the electronic density of states n(Ef), due to lattice expansion when different R ions are inserted, has the correct order of magnitude to explain the evolution of the CDW properties.

Brouet, V.; Yang, W.L.; Zhou, X.J.; Hussain, Z.; Moore, R.G.; He, R.; Lu, D.H.; Shen, Z.X.; Laverock, J.; Dugdale, S.; Ru, N.; Fisher, I.R.

2010-02-15T23:59:59.000Z

29

First Observation of Plasmarons in Graphene  

NLE Websites -- All DOE Office Websites (Extended Search)

First Observation of Plasmarons in Graphene Print An international team of scientists performing angle-resolved photoemission spectroscopy (ARPES) experiments at ALS Beamline 7.0.1...

30

Interaction of Metallophthalocyanines (Mpc, M=Co, Ni) on Au(001): Ultraviolet Photoemission Spectroscopy and Low Energy Electron Diffraction Study  

Science Conference Proceedings (OSTI)

Thin films of metallophthalocyanine (MPc,M=Co,Ni) evaporated onto a '5x20' reconstructed Au(001) substrate at room temperature have been investigated by employing low energy electron diffraction (LEED) and ultraviolet photoelectron spectroscopy (UPS). The LEED images from NiPc thin films show that the overlayers are highly ordered with a square unit cell of 12.8x12.8 {angstrom}{sup 2} aligned along the {l_angle}110{r_angle} and {l_angle}1{bar 1}0{r_angle} axes of the Au(001) substrate. For CoPc, the LEED pattern reveals the superposition of multiple rotationally equivalent domains of a 12.9x12.9 {angstrom}{sup 2} square lattice which are rotated by 16{sup o} with respect to each other. The contrast between NiPc and CoPc on Au(001) is further demonstrated in the interfacial electronic structure. UPS studies of the interfacial layers of NiPc deposited on the hexagonally reconstructed gold substrate indicate that NiPc physisorbs on the gold surface as evidenced by a uniform molecular orbital (MO) shift. The CoPc MO's, on the other hand, indicates a charge transfer at the interface, evidenced by the 13a{sub 1g} MO interacting with the Au surface.

Ellis,T.; Park, K.; Ulrich, M.; Hulbert, S.; Rowe, J.

2006-01-01T23:59:59.000Z

31

Plasmon Enhanced Photoemission  

E-Print Network (OSTI)

53 PNNL Pacific Northwest NationalNational Laboratory (PNNL) using two light sources: the Ti:MULTI-PHOTON PHOTOEMISSION PNNL LBNL 800 nm 805 nm f laser ?

Polyakov, Aleksandr N.

2012-01-01T23:59:59.000Z

32

Correlation of polycrystalline Cu(In,Ga)Se{sub 2} device efficiency with homojunction depth and interfacial structure: X-ray photoemission and positron annihilation spectroscopic characterization  

DOE Green Energy (OSTI)

Angled-resolved high resolution photoemission measurements on valence band electronic structure and Cu 2p, In 3d, Ga 2p, and Se 3d core lines were used to evaluate surface and near-surface chemistry of CuInSe{sub 2} and Cu(In,Ga)Se{sub 2} device grade thin films. XPS compositional depth profiles were also acquired from the near-surface region, and bonding of the Cu, In, Ga, and Se was determined as a function of depth. A Cu-poor region was found, indicating CuIn{sub 5}Se{sub 8} or a CuIn{sub 3}Se{sub 5}-In{sub 2}Se{sub 3} mixture. Correlation between the depth of the Cu-poor region/bulk interface and device efficiency showed that the depth was 115 {angstrom} for a 16.4% CIGS device, 240 {angstrom} for a 15.0% CIGS, and 300 {angstrom} for 14.0% CIGS, with similar trends for CIS films. The surface region is n-type, the bulk is p-type, with a 0.5 eV valence band offset. Depth of homojunction may be the determining factor in device performance. Positron annihilation spectroscopy gave similarly illuminating results.

Nelson, A.J.; Sobol, P.E.; Gabor, A.M.; Contreras, M.A. [National Renewable Energy Lab., Golden, CO (United States); Asoka-Kumar, P.; Lynn, K.G. [Brookhaven National Lab., Upton, NY (United States)

1994-06-01T23:59:59.000Z

33

Pt–metal oxide aerogel catalysts: X-ray photoemission investigation  

Science Conference Proceedings (OSTI)

X-ray photoemission spectroscopy was used to study Pt–metal oxide aerogel catalysts that have been developed to respond to increased NO x emissions of lean-burn engines. Lean-burn engines

A. J. Nelson; John G. Reynolds; R. D. Sanner; P. R. Coronado; L. M. Hair

2001-01-01T23:59:59.000Z

34

Microsoft Word - Photoemission  

NLE Websites -- All DOE Office Websites (Extended Search)

Photoemission Photoemission Resources Available - BE Mid 2012 Mid 2014 Mid 2016 Mid 2017 Beamline X-ray Source Total Total Total Total NSLS 2.5 2.5 0 0 U5UA undulator 1 1 0 0 U13 undulator 1 1 0 0 X1A1* undulator 0.5 0.5 0 0 *ambient pressure APS 0.3 0.3 0.3 0.3 4 ID C undulator 0.3 0.3 0.3 0.3 ALS 3 3 3 3 7.0.1 U5 - undulator 0 0 0 0 Decommissioned summer 2012 10.0.1 U10 - undulator 1 1 1 1 12.0.1 U8 - undulator 0.5 0.5 0.5 0.5 11.0.1.1* EPU5 - undulator 0.5 0.5 0.5 0.5 *PEEM 9.3.2** bend 1 1 1 1 *ambient pressure SSRL 1 1 1 1 BL5-4 undulator 1 1 1 1

35

DEVELOPMENT OF NEXT-GENERATION DETECTORS AND INSTRUMENTATION FOR PHOTOELECTRON SPECTROSCOPY, DIFFRACTION AND HOLOGRAPHY  

SciTech Connect

We have developed a new multichannel detector for use in photoelectron spectroscopy (as well as other types of high-count-rate spectroscopy) that will operate at rates of up to 1 GHz. Such detectors are crucial to the full utilization of the high-brightness radiation generated by third-generation synchrotron radiation sources. In addition, new software and hardware has been developed to permit rapidly and accurately scanning photoelectron spectra that will be accumulated in as little as a 200 micros. A versatile next-generation sample goniometer permitting equally rapid scanning of specimen angles or photon energies for angle-resolved photoemission studies, photoelectron diffraction, and photoelectron holography measurements, and cooling to below 10K has also been designed and constructed. These capabilities have been incorporated into a unique photoelectron spectrometer/diffractometer at the Advanced Light Source of the Lawrence Berkeley National Laboratory; this experimental system includes ultrahigh energy resolution, in situ rotation, variable polarization, and optional spin detection. This overall system is now being used in studies of a variety of problems including magnetic metals and oxides; metal/metal, metal/metal oxide, and metal-oxide/metal-oxide multilayers; and systems exhibiting giant and colossal magnetoresistance.

Charles S. Fadley, Principal Investigator

2005-10-16T23:59:59.000Z

36

Correlation of conductivity and angle integrated valence band photoemission  

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Correlation of conductivity and angle integrated valence band photoemission Correlation of conductivity and angle integrated valence band photoemission characteristics in single crystal iron perovskites for 300 K < T < 800 K: Comparison of surface and bulk sensitive methods Title Correlation of conductivity and angle integrated valence band photoemission characteristics in single crystal iron perovskites for 300 K < T < 800 K: Comparison of surface and bulk sensitive methods Publication Type Journal Article Year of Publication 2010 Authors Braun, Artur, Bongjin S. Mun, Yun Sun, Z. Liu, Oliver Gröning, R. Mäder, Selma Erat, Xueyuan Zhang, Samuel S. Mao, Ekaterina Pomjakushina, Kazimierz Conder, and Thomas Graule Journal Journal of Electron Spectroscopy and Related Phenomena Volume 181 Issue 1 Pagination 56-62 Date Published 07/2013

37

Oxygen-diffusion limited metal combustions in Zr, Ti, and Fe foils: Time- and angle-resolved x-ray diffraction studies  

Science Conference Proceedings (OSTI)

The transient phase and chemical transformations of diffusion controlled metal combustions in bulk Zr, Ti, and Fe foils have been investigated, in situ, using novel time- and angle-resolved x-ray diffraction (TARXD). The TARXD employs monochromatic synchrotron x-rays and a fast-rotating diffracted beam chopper resolving the diffraction image temporally in time-resolution of {approx}45 {mu}s along the azimuth on a 2D pixel array detector. The metal foil strips (10-25 {mu}m in thickness) are ignited using a pulsed electrical heating with a typical heating rate of {approx}10{sup 6} K/s. The x-ray results indicate that the combustion occurs in molten metals, producing a wide range of stoichiometric solid oxides. It reflects an enhanced oxygen solubility and mobility of molten metals with respect to those of solid metals. However, the initial oxides formed are mainly oxygen-deficient metal oxides of ZrO, TiO, and FeO/Fe{sub 3}O{sub 4} - the lowest suboxides stable at these high temperatures. These transition metal monoxides further react with unreacted molten metals, yielding the secondary products of Zr{sub 3}O, Ti{sub 3}O, and Ti{sub 2}O - but not in FeO/Fe{sub 3}O{sub 4}. On the other hand, the higher stoichiometric oxides of ZrO{sub 2} and TiO{sub 2} are formed in the later time only on the metal surface. These results clearly indicate that the combustion process of metal strips is diffusion limited and strongly depends on the solubility and diffusivity of oxygen into molten metals. The time-resolved diffraction data reveals no evidence for metal oxidation in solids, but a series of temperature-induced polymorphic phase transitions. The dynamic thermal expansibility of Fe measured in the present fast heating experiments is similar to those in static conditions (3.3*10{sup -5}/K vs 3.5*10{sup -5}/K for {alpha}-Fe and 6.5*10{sup -5}/K versus 7.0*10{sup -5}/K for {gamma}-Fe).

Wei, Haoyan; Yoo, Choong-Shik; Chen, Jing-Yin; Shen, Guoyin (CIW); (WSU)

2012-04-30T23:59:59.000Z

38

How Electron Spectroscopy with Synchrotron Light Can Help Us Understand High-Tc Superconductivity and Other Complex States of Matter  

SciTech Connect

All the physical, chemical, and mechanical properties of materials are controlled by electrons that occupy the highest energy levels in solids, those near the Fermi energy. Many techniques were developed to study those electrons, leading to the great successes of condensed matter physics. Newer and complex materials, such as the high-temperature superconductors, tend to exhibit very large anisotropies in their physical properties, requiring a more detailed knowledge of the behavior of electrons not only as a function of their energy, but also their momentum. Angle-resolved photoemission can contribute to our understanding by providing a great deal of information on many of the momentum-dependent properties of electrons and their interactions. In this talk, I will present a brief overview of how a long-term and focused collaboration between scientists at Argonne and other institutions has contributed to making angle-resolved photoemissions a most useful tool in the study of complex states of matter.

Campuzano, Juan Carlos [University of Illinois, Chicago

2012-03-07T23:59:59.000Z

39

SRI2013 | Workshop 5 - Photoemission Spectroscopy - the ...  

Science Conference Proceedings (OSTI)

... 12:30 — 13:00, Tomasz Durakiewic (LANL) Time-resolved ARPES and f-electrons: the promise, the reality, the future. 13:00 — 14:00, Lunch. ...

40

Watching Electrons Transfer from Metals to Insulators using Two Photon Photoemission  

SciTech Connect

Ultrafast angle-resolved two photon photoemission was used to study the dynamics and interfacial band structure of ultrathin films adsorbed onto Ag(111). Studies focused on the image potential state (IPS) in each system as a probe for measuring changes in electronic behavior in differing environments. The energetics and dynamics of the IPS at the toluene/Ag(111) interface are strongly dependent upon coverage. For a single monolayer, the first IPS is bound by 0.81 eV below the vacuum level and has a lifetime of 50 femtoseconds (fs). Further adsorption of toluene creates islands of toluene with an exposed wetting layer underneath. The IPS is then split into two peaks, one corresponding to the islands and one corresponding to the monolayer. The wetting layer IPS shows the same dynamics as the monolayer, while the lifetime of the islands increases exponentially with increasing thickness. Furthermore, the island IPS transitions from delocalized to localized within 500 fs, and electrons with larger parallel momenta decay much faster. Attempts were made using a stochastic model to extract the rates of localization and intraband cooling at differing momenta. In sexithiophene (6T) and dihexyl-sexithiophene (DH6T), the IPS was used as a probe to see if the nuclear motion of spectating side chains can interfere with molecular conduction. The energy and band mass of the IPS was measured for 6T and two geometries of DH6T on Ag(111). Electrons injected into the thicker coverages of DH6T grew exponentially heavier until they were completely localized by 230 fs, while those injected into 6T remained nearly free electron like. Based off of lifetime arguments and the density of defects, the most likely cause for the mass enhancement of the IPS in this system is small polaron formation caused by coupling of the electron to vibrations of the alkyl substituents. The energetic relaxation of the molecular adsorbate was also measured to be 20 meV/100 fs for the DH6T, and 0 meV/100 fs for the 6T. This relaxation is consistent with the localization of the charge creating a barrier for it moving from one lattice site to a neighboring one. Finally, the IPS was used to study the evolution of the surface band gap at the Mg/Ag(111) interface. The Mg(0001) surface band gap lies 1.6 eV below the Fermi level, and consequently shows no peak in the projected density of states for the IPS. A method for creating layer by layer growth of Mg on Ag(111) was determined using Auger Spectroscopy and low energy electron diffraction. By monitoring the decay of the intensity of the IPS versus coverage, it was determined that four layers of magnesium on Ag(111) is sufficient to completely eliminate the surface band gap

Johns, James E.

2010-05-01T23:59:59.000Z

Note: This page contains sample records for the topic "angle-resolved photoemission spectroscopy" from the National Library of EnergyBeta (NLEBeta).
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41

Spectroscopy  

NLE Websites -- All DOE Office Websites (Extended Search)

Spectroscopy Spectroscopy Spectroscopy Print In spectroscopy experiments, a sample is illuminated with light and the various product particles (electrons, ions, or fluorescent photons) are detected and analyzed.The unifying feature is that some "property" of a material is measured as the x-ray (photon) energy is swept though a range of values. At the most basic level, one measures the absorption, transmission, or reflectivity of a sample as a function of photon energy. Probes that use the vacuum ultraviolet (VUV) region of the spectrum (10-100 eV) are very well matched to the elucidation of bonding in solids, surfaces, and molecules; to the investigation of electron-electron correlations in solids, atoms, and ions; and to the study of reaction pathways in chemical dynamics. At the lowest end of this energy range (below 1 eV) we have infrared, far-infrared, and terahertz spectroscopies, which are well matched to vibrational modes and other modes of excitation.

42

Spectroscopy  

NLE Websites -- All DOE Office Websites (Extended Search)

Spectroscopy Print Spectroscopy Print In spectroscopy experiments, a sample is illuminated with light and the various product particles (electrons, ions, or fluorescent photons) are detected and analyzed.The unifying feature is that some "property" of a material is measured as the x-ray (photon) energy is swept though a range of values. At the most basic level, one measures the absorption, transmission, or reflectivity of a sample as a function of photon energy. Probes that use the vacuum ultraviolet (VUV) region of the spectrum (10-100 eV) are very well matched to the elucidation of bonding in solids, surfaces, and molecules; to the investigation of electron-electron correlations in solids, atoms, and ions; and to the study of reaction pathways in chemical dynamics. At the lowest end of this energy range (below 1 eV) we have infrared, far-infrared, and terahertz spectroscopies, which are well matched to vibrational modes and other modes of excitation.

43

Spectroscopy  

NLE Websites -- All DOE Office Websites (Extended Search)

Spectroscopy Print Spectroscopy Print In spectroscopy experiments, a sample is illuminated with light and the various product particles (electrons, ions, or fluorescent photons) are detected and analyzed.The unifying feature is that some "property" of a material is measured as the x-ray (photon) energy is swept though a range of values. At the most basic level, one measures the absorption, transmission, or reflectivity of a sample as a function of photon energy. Probes that use the vacuum ultraviolet (VUV) region of the spectrum (10-100 eV) are very well matched to the elucidation of bonding in solids, surfaces, and molecules; to the investigation of electron-electron correlations in solids, atoms, and ions; and to the study of reaction pathways in chemical dynamics. At the lowest end of this energy range (below 1 eV) we have infrared, far-infrared, and terahertz spectroscopies, which are well matched to vibrational modes and other modes of excitation.

44

High Energy Photoemission: Development of a New Electrostatic Lens for a Novel High Resolution Spectrometer  

SciTech Connect

In recent years growing interest has been dedicated to photoemission experiments at high energy because a significant bulk sensitivity in photoemission measurements can be achieved only by increasing the kinetic energy of the analysed photoelectrons. Within the 5th European framework, a RTD project named VOLPE (VOLume PhotoEmission from solids) has been funded. Aim of the project is to measure bulk electronic properties on solids by the Photoemission Spectroscopy with Synchrotron Radiation preserving an energy resolution comparable to modern surface sensitive photoemission spectra. This will be possible by performing photoemission experiments in a photolectron Kinetic Energy range of 6-10 keV, keeping the overall energy resolution at 20-30 meV. Presently, the beamline ID16 at ESRF posses the necessary characteristics (1011 photons/sec and 15-100 meV resolution at photon energies between 6 keV and 15 keV) to perform these class of experiments, while a new spectrometer is being developed in the framework of VOLPE project. This spectrometer is an hemispherical deflector analyser with electrostatic input lens and 2D position sensitive detector. The spectrometer will be characterised by an ultimate resolving power of 3 105 at 10 keV. We will report on the particular lens system developed for this project which is optimised to guarantee very high retarding ratio, between 50 and 600, with constant linear magnification. A prototype of this lens has been realised and we will report on the first measurements performed at INFM, Unita Roma Tre.

Paolicelli, G.; Fondacaro, A.; Offi, F. [INFM, Unita Roma Tre, Via della Vasca Navale 84 -I 00146 Rome (Italy); Stefani, G. [INFM, Unita Roma Tre, Via della Vasca Navale 84 -I 00146 Rome (Italy); Dip. di Fisica 'E. Amaldi', Universita Roma Tre Via della Vasca Navale 84-I 00146 Rome (Italy)

2004-05-12T23:59:59.000Z

45

Raising Photoemission Efficiency with Surface Acoustic Waves  

Science Conference Proceedings (OSTI)

We are developing a novel technique that may help increase the efficiency and reduce costs of photoelectron sources used at electron accelerators. The technique is based on the use of Surface Acoustic Waves (SAW) in piezoelectric materials, such as GaAs, that are commonly used as photocathodes. Piezoelectric fields produced by the traveling SAW spatially separate electrons and holes, reducing their probability of recombination, thereby enhancing the photoemission quantum efficiency of the photocathode. Additional advantages could be increased polarization provided by the enhanced mobility of charge carriers that can be controlled by the SAW and the ionization of optically-generated excitons resulting in the creation of additional electron-hole pairs. It is expected that these novel features will reduce the cost of accelerator operation. A theoretical model for photoemission in the presence of SAW has been developed, and experimental tests of the technique are underway.

A. Afanasev, F. Hassani, C.E. Korman, V.G. Dudnikov, R.P. Johnson, M. Poelker, K.E.L. Surles-Law

2012-07-01T23:59:59.000Z

46

Space charge effect and mirror charge effect in photoemission spectroscopy  

E-Print Network (OSTI)

is a third-generation synchrotron source which generatesthird-generation synchrotron light source. This value istypical third-generation synchrotron light source, which is

2004-01-01T23:59:59.000Z

47

SSRL HEADLINES Jul 2001  

NLE Websites -- All DOE Office Websites (Extended Search)

1 Jul, 2001 1 Jul, 2001 _____________________________________________________________________________ Contents of This Issue: Science Highlight - Complex Materials Research by Angle-Resolved Photoemission Spectroscopy: Challenging the Mystery of the High Tc Superconductivity 2000-2001 Experimental Run Highlights Stanford-Berkeley 2001 SR Summer School: A Successful Start to the First in a Series SSRL Well Represented at the American Crystallographic Association Meeting The Shutdown Clock is Ticking BL10 Insertion Device Repair on Track for November User Operations Semi-annual SPEAR3 Lehman Review SSRL's 28th Annual Users' Meeting is Coming Soon! User Research Administration Announcements Job Opportunities at SSRL 1. Science Highlight - Complex Materials Research by Angle-Resolved

48

Technique Subgroupings Spectroscopy  

NLE Websites -- All DOE Office Websites (Extended Search)

and NSLS-II beamlines according to DOE Technique Scheme and NSLS-II beamlines according to DOE Technique Scheme Technique Subgroupings Spectroscopy 01 - Low Energy Spectroscopy Infrared Photoemission U12IR, U4IR / MET* U5UA, U13 / ESM 02 - Soft X-Ray Spectroscopy Soft X-ray Spectroscopy Tender XAS U4B, U7A, X24A / SST, SSS* X15B, X19A / TES* 03 - Hard X-ray Spectroscopy EXAFS X3A, X3B, X11A, X11B, X18A, X18B, X23A2 / ISS, BMM, QAS*, XAS* 04 - Optics/Calibration/Metrology U3C,X8A/ OFT,MID Scattering 05 X-ray Diffraction X-Ray Powder Diffraction Extreme Conditions Energy Dispersive Micro-Beam Diffraction X7B,X10B,X14A,X16C,X17A / XPD,IXD* X17B2,X17B3,X17C / XPD, TEC*, 4DE* X17B1, X17B2 / NA X13B / MXD* 06 MX, footprinting Protein Crystallography X-ray footprinting X4A, X4C, X6A, X12B, X12C, X25, X29 / FMX, AMX, NYX;

49

Beamline 4.0.3  

NLE Websites -- All DOE Office Websites (Extended Search)

3 Print 3 Print High-resolution spectroscopy of complex materials (MERLIN) Endstations: MERIXS: High-resolution inelastic scattering ARPES: Angle-resolved photoemission spectroscopy GENERAL BEAMLINE INFORMATION Operational 2011 Source characteristics 9.0-cm-period quasiperiodic elliptical polarization undulator (EPU9) Energy range 9eV-120eV with current gratings Monochromator Variable-included-angle spherical grating monochromator (SGM) Calculated flux (1.9 GeV, 400 mA) 1012 photons/s/0.01%BW at 100 eV Resolving power (E/ΔE) High flux 1200 lines/mm; ~1/25,000 Endstations High-resolution inelastic scattering (MERIXS) and ARPES Characteristics Milli-Electron-volt Resolution beamLINe (MERLIN): Ultrahigh-resolution inelastic scattering and angle-resolved photoemission

50

Beamline 4.0.3  

NLE Websites -- All DOE Office Websites (Extended Search)

3 Print 3 Print High-resolution spectroscopy of complex materials (MERLIN) Endstations: MERIXS: High-resolution inelastic scattering ARPES: Angle-resolved photoemission spectroscopy GENERAL BEAMLINE INFORMATION Operational 2011 Source characteristics 9.0-cm-period quasiperiodic elliptical polarization undulator (EPU9) Energy range 9eV-120eV with current gratings Monochromator Variable-included-angle spherical grating monochromator (SGM) Calculated flux (1.9 GeV, 400 mA) 1012 photons/s/0.01%BW at 100 eV Resolving power (E/ΔE) High flux 1200 lines/mm; ~1/25,000 Endstations High-resolution inelastic scattering (MERIXS) and ARPES Characteristics Milli-Electron-volt Resolution beamLINe (MERLIN): Ultrahigh-resolution inelastic scattering and angle-resolved photoemission

51

Beamline 4.0.3  

NLE Websites -- All DOE Office Websites (Extended Search)

3 Print 3 Print High-resolution spectroscopy of complex materials (MERLIN) Endstations: MERIXS: High-resolution inelastic scattering ARPES: Angle-resolved photoemission spectroscopy GENERAL BEAMLINE INFORMATION Operational 2011 Source characteristics 9.0-cm-period quasiperiodic elliptical polarization undulator (EPU9) Energy range 9eV-120eV with current gratings Monochromator Variable-included-angle spherical grating monochromator (SGM) Calculated flux (1.9 GeV, 400 mA) 1012 photons/s/0.01%BW at 100 eV Resolving power (E/ΔE) High flux 1200 lines/mm; ~1/25,000 Endstations High-resolution inelastic scattering (MERIXS) and ARPES Characteristics Milli-Electron-volt Resolution beamLINe (MERLIN): Ultrahigh-resolution inelastic scattering and angle-resolved photoemission

52

Beamline 4.0.3  

NLE Websites -- All DOE Office Websites (Extended Search)

3 Print 3 Print High-resolution spectroscopy of complex materials (MERLIN) Endstations: MERIXS: High-resolution inelastic scattering ARPES: Angle-resolved photoemission spectroscopy GENERAL BEAMLINE INFORMATION Operational 2011 Source characteristics 9.0-cm-period quasiperiodic elliptical polarization undulator (EPU9) Energy range 9eV-120eV with current gratings Monochromator Variable-included-angle spherical grating monochromator (SGM) Calculated flux (1.9 GeV, 400 mA) 1012 photons/s/0.01%BW at 100 eV Resolving power (E/ΔE) High flux 1200 lines/mm; ~1/25,000 Endstations High-resolution inelastic scattering (MERIXS) and ARPES Characteristics Milli-Electron-volt Resolution beamLINe (MERLIN): Ultrahigh-resolution inelastic scattering and angle-resolved photoemission

53

Beamline 4.0.3  

NLE Websites -- All DOE Office Websites (Extended Search)

3 Print 3 Print High-resolution spectroscopy of complex materials (MERLIN) Endstations: MERIXS: High-resolution inelastic scattering ARPES: Angle-resolved photoemission spectroscopy GENERAL BEAMLINE INFORMATION Operational 2011 Source characteristics 9.0-cm-period quasiperiodic elliptical polarization undulator (EPU9) Energy range 9eV-120eV with current gratings Monochromator Variable-included-angle spherical grating monochromator (SGM) Calculated flux (1.9 GeV, 400 mA) 1012 photons/s/0.01%BW at 100 eV Resolving power (E/ΔE) High flux 1200 lines/mm; ~1/25,000 Endstations High-resolution inelastic scattering (MERIXS) and ARPES Characteristics Milli-Electron-volt Resolution beamLINe (MERLIN): Ultrahigh-resolution inelastic scattering and angle-resolved photoemission

54

Beamline 4.0.3  

NLE Websites -- All DOE Office Websites (Extended Search)

3 Print 3 Print High-resolution spectroscopy of complex materials (MERLIN) Endstations: MERIXS: High-resolution inelastic scattering ARPES: Angle-resolved photoemission spectroscopy GENERAL BEAMLINE INFORMATION Operational 2011 Source characteristics 9.0-cm-period quasiperiodic elliptical polarization undulator (EPU9) Energy range 9eV-120eV with current gratings Monochromator Variable-included-angle spherical grating monochromator (SGM) Calculated flux (1.9 GeV, 400 mA) 1012 photons/s/0.01%BW at 100 eV Resolving power (E/ΔE) High flux 1200 lines/mm; ~1/25,000 Endstations High-resolution inelastic scattering (MERIXS) and ARPES Characteristics Milli-Electron-volt Resolution beamLINe (MERLIN): Ultrahigh-resolution inelastic scattering and angle-resolved photoemission

55

Beamline 4.0.3  

NLE Websites -- All DOE Office Websites (Extended Search)

3 Print 3 Print High-resolution spectroscopy of complex materials (MERLIN) Endstations: MERIXS: High-resolution inelastic scattering ARPES: Angle-resolved photoemission spectroscopy GENERAL BEAMLINE INFORMATION Operational 2011 Source characteristics 9.0-cm-period quasiperiodic elliptical polarization undulator (EPU9) Energy range 9eV-120eV with current gratings Monochromator Variable-included-angle spherical grating monochromator (SGM) Calculated flux (1.9 GeV, 400 mA) 1012 photons/s/0.01%BW at 100 eV Resolving power (E/ΔE) High flux 1200 lines/mm; ~1/25,000 Endstations High-resolution inelastic scattering (MERIXS) and ARPES Characteristics Milli-Electron-volt Resolution beamLINe (MERLIN): Ultrahigh-resolution inelastic scattering and angle-resolved photoemission

56

Beamline 4.0.3  

NLE Websites -- All DOE Office Websites (Extended Search)

3 Print 3 Print High-resolution spectroscopy of complex materials (MERLIN) Endstations: MERIXS: High-resolution inelastic scattering ARPES: Angle-resolved photoemission spectroscopy GENERAL BEAMLINE INFORMATION Operational 2011 Source characteristics 9.0-cm-period quasiperiodic elliptical polarization undulator (EPU9) Energy range 9eV-120eV with current gratings Monochromator Variable-included-angle spherical grating monochromator (SGM) Calculated flux (1.9 GeV, 400 mA) 1012 photons/s/0.01%BW at 100 eV Resolving power (E/ΔE) High flux 1200 lines/mm; ~1/25,000 Endstations High-resolution inelastic scattering (MERIXS) and ARPES Characteristics Milli-Electron-volt Resolution beamLINe (MERLIN): Ultrahigh-resolution inelastic scattering and angle-resolved photoemission

57

Zhi-XunShen, 2009 | U.S. DOE Office of Science (SC)  

Office of Science (SC) Website

angle-resolved photoemission to advance understanding of strongly correlated electron systems including high-transition temperature superconductors and other complex...

58

Steve Kevan  

NLE Websites -- All DOE Office Websites (Extended Search)

high-resolution angle-resolved photoemission at the National Synchrotron Light Source (NSLS) at Brookhaven National Laboratory. He focused in particular on high-resolution...

59

Symmetry Breaking in Few Layer Graphene Films  

SciTech Connect

Recently, it was demonstrated that the quasiparticledynamics, the layer-dependent charge and potential, and the c-axisscreening coefficient could be extracted from measurements of thespectral function of few layer graphene films grown epitaxially on SiCusing angle-resolved photoemission spectroscopy (ARPES). In this articlewe review these findings, and present detailed methodology for extractingsuch parameters from ARPES. We also present detailed arguments againstthe possibility of an energy gap at the Dirac crossing ED.

Bostwick, A.; Ohta, T.; McChesney, J.L.; Emtsev, K.; Seyller,Th.; Horn, K.; Rotenberg, E.

2007-05-25T23:59:59.000Z

60

Photoelectron Spectroscopy under Ambient Pressure and Temperature Conditions  

SciTech Connect

We describe the development and applications of novel instrumentation for photoemission spectroscopy of solid or liquid surfaces in the presence of gases under ambient conditions or pressure and temperature. The new instrument overcomes the strong scattering of electrons in gases by the use of an aperture close to the surface followed by a differentially-pumped electrostatic lens system. In addition to the scattering problem, experiments in the presence of condensed water or other liquids require the development of special sample holders to provide localized cooling. We discuss the first two generations of Ambient Pressure PhotoEmission Spectroscopy (APPES) instruments developed at synchrotron light sources (ALS in Berkeley and BESSY in Berlin), with special focus on the Berkeley instruments. Applications to environmental science and catalytic chemical research are illustrated in two examples.

Ogletree, D. Frank; Bluhm, Hendrik; Hebenstreit, Eleonore B.; Salmeron, Miquel

2009-02-27T23:59:59.000Z

Note: This page contains sample records for the topic "angle-resolved photoemission spectroscopy" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


61

SPIN POLARIZED PHOTOELECTRON SPECTROSCOPY AS A PROBE OF MAGNETIC SYSTEMS.  

SciTech Connect

Spin-polarized photoelectron spectroscopy has developed into a versatile tool for the study of surface and thin film magnetism. In this chapter, we examine the methodology of the technique and its recent application to a number of different problems. We first examine the photoemission process itself followed by a detailed review of spin-polarization measurement techniques and the related experimental requirements. We review studies of spin polarized surface states, interface states and quantum well states followed by studies of the technologically important oxide systems including half-metallic transition metal oxides, ferromagnet/oxide interfaces and the antiferromagnetic cuprates that exhibit high Tc Superconductivity. We also discuss the application of high-resolution photoemission with spin resolving capabilities to the study of spin dependent self energy effects.

JOHNSON, P.D.; GUNTHERODT, G.

2006-11-01T23:59:59.000Z

62

Spectroscopic investigations of small molecule interactions on metal oxide surfaces. Progress report, September 1, 1979-October 31, 1980  

DOE Green Energy (OSTI)

Significant advances were made over the past year in surveying with angle integrated uv photoelectron spectroscopy (UPS) the interactions of general classes of chemically important small molecules with metal oxide surfaces, and in elucidating in detail the geometric and electronic structures of the small molecule-surface complexes observed by angle resolved UPS. Progress can be divided into several areas: (1) a detailed understanding of the unique active site structures associated with the interaction of CO with ZnO utilizing angle integrated and angle resolved photoemission spectroscopy; (2) initiating survey studies into new small molecule systems with emphasis on hydrogen and ethylene; (3) successful construction and testing of a high resoltuion electron energy loss spectrometer (HREELS).

Solomon, E.I.; McFeeley, F.R.

1980-10-31T23:59:59.000Z

63

PHOTOEMISSION AS A PROBE OF THE COLLECTIVE EXCITATIONS IN CONDENSED MATTER SYSTEMS.  

SciTech Connect

New developments in instrumentation have recently allowed photoemission measurements to be performed with very high energy and momentum resolution.[1] This has allowed detailed studies of the self-energy corrections to the lifetime and mass renormalization of excitations in the vicinity of the Fermi level. These developments come at an opportune time. Indeed the discovery of high temperature superconductivity in the cuprates and related systems is presenting a range of challenges for condensed matter physics.[2] Does the mechanism of high T{sub c} superconductivity represent new physics? Do we need to go beyond Landau's concept of the Fermi liquid?[3] What, if any, is the evidence for the presence or absence of quasiparticles in the excitation spectra of these complex oxides? The energy resolution of the new instruments is comparable to or better than the energy or temperature scale of superconductivity and the energy of many collective excitations. As such, photoemission has again become recognized as an important probe of condensed matter. Studies of the high T{sub c} superconductors and related materials are aided by the observation that they are two dimensional. To understand this, we note that the photoemission process results in both an excited photoelectron and a photohole in the final state. Thus the experimentally measured photoemission peak is broadened to a width reflecting contributions from both the finite lifetime of the photohole and the momentum broadening of the outgoing photoelectron.

JOHNSON, P.D.; VALLA, T.

2006-08-01T23:59:59.000Z

64

Optimization of NSLS-II Blade X-ray Beam Position Monitors: from Photoemission type to Diamond Detector  

E-Print Network (OSTI)

Optimization of blade type X-ray Beam Position Monitors (XBPM) was performed for NSLS-II undulator IVU20. Blade material, configuration and operation principle was analyzed to improve XBPM performance. Optimization is based on calculation of the XBPM signal spatial distribution. Along with standard photoemission blades, Diamond Detector Blade (DDB) was analyzed as XBPM signal source. Analyses revealed, that Diamond Detector Blade XBPM would allow overcoming drawbacks of the photoemission type XBPMs.

Ilinski, Petr

2013-01-01T23:59:59.000Z

65

Plasmonic Field Enhancement of Individual Nanoparticles by Correlated Scanning and Photoemission Electron Microscopy  

SciTech Connect

We present results of a combined two-photon photoemission and scanning electron microscopy investigation to determine the electromagnetic enhancement factors of silver-coated spherical nanoparticles deposited on an atomically flat mica substrate. Femtosecond laser excitation, of the nanoparticles, produces intense photoemission, attributed to near-resonant excitation of localized surface plasmons. Enhancement factors are determined by comparing the respective two-photon photoemission yield measured for equal areas between single nanoparticles to that of the surrounding flat surface. For s-polarized, 400 nm (~ 3.1 eV) femtosecond radiation a distribution of enhancement factors are found with a large percentage (77%) of the nanoparticles falling within a median range. A correlated scanning electron microscopy analysis demonstrated that the nanoparticles typifying the median of the distribution were characterized by ideal spherical shapes and defect-free morphologies. The single largest enhancement factors were in contrast produced by a very small percentage (8%) of the total, for which evidence of silver defect anomalies were found that contributed to the overall structure of the nanoparticle. Comparisons are made between the experimentally measured enhancement factors and previously reported theoretical predictions of the localized surface plasmon near-field intensities for isolated nanometer-sized silver spheres.

Peppernick, Samuel J.; Joly, Alan G.; Beck, Kenneth M.; Hess, Wayne P.

2011-01-21T23:59:59.000Z

66

Pitch angle resolved measurements of escaping charged fusion products in TFTR  

SciTech Connect

Measurements of the flux of charged fusion products escaping from the TFTR plasma have been made with a new type of detector which can resolve the particle flux vs. pitch angle, energy, and time. The design of this detector is described, and results from the 1987 TFTR run are presented. These results are roughly consistent with predictions from a simple first-orbit particle loss model with respect to the pitch angle, energy, time, and plasma current dependence of the signals. 11 refs., 9 figs.

Zweben, S.J.

1989-01-01T23:59:59.000Z

67

Evidence for three-dimensional Fermi-surface topology of the layered electron-doped iron superconductor Ba(Fe1 xCox)2As2  

SciTech Connect

The electronic structure of electron doped iron-arsenide superconductors Ba(Fe{sub 1-x}Co{sub x}){sub 2}As{sub 2} has been measured with Angle Resolved Photoemission Spectroscopy. The data reveal a marked photon energy dependence of points in momentum space where the bands cross the Fermi energy, a distinctive and direct signature of three-dimensionality in the Fermi surface topology. By providing a unique example of high temperature superconductivity hosted in layered compounds with three-dimensional electronic structure, these findings suggest that the iron-arsenides are unique materials, quite different from the cuprates high temperature superconductors.

Vilmercati, P. [University of Tennessee, Knoxville (UTK); Fedorov, A. V. [Lawrence Berkeley National Laboratory (LBNL); Vobornik, I. [TASC National Laboratory, Trieste, Italy; Manju, U. [TASC National Laboratory, Trieste, Italy; Panaccione, G. [TASC National Laboratory, Trieste, Italy; Goldoni, A. [Sincrotrone Trieste, Basovizza, Italy; Safa-Sefat, Athena [ORNL; McGuire, Michael A [ORNL; Sales, Brian C [ORNL; Jin, Rongying [ORNL; Mandrus, David [ORNL; Singh, David J [ORNL; Mannella, Norman [ORNL

2009-01-01T23:59:59.000Z

68

Standing-wave excited soft x-ray photoemission microscopy: application to Co microdot magnetic arrays  

SciTech Connect

We demonstrate the addition of depth resolution to the usual two-dimensional images in photoelectron emission microscopy (PEEM), with application to a square array of circular magnetic Co microdots. The method is based on excitation with soft x-ray standing-waves generated by Bragg reflection from a multilayer mirror substrate. Standing wave is moved vertically through sample simply by varying the photon energy around the Bragg condition. Depth-resolved PEEM images were obtained for all of the observed elements. Photoemission intensities as functions of photon energy were compared to x-ray optical calculations in order to quantitatively derive the depth-resolved film structure of the sample.

Gray, Alexander; Kronast, Florian; Papp, Christian; Yang, See-Hun; Cramm, Stefan; Krug, Ingo P.; Salmassi, Farhad; Gullikson, Eric M.; Hilken, Dawn L.; Anderson, Erik H.; Fischer, Peter; Durr, Hermann A.; Schneider, Claus M.; Fadley, Charles S.

2010-10-29T23:59:59.000Z

69

Strong-field above-threshold photoemission from sharp metal tips  

E-Print Network (OSTI)

We present energy-resolved measurements of electron emission from sharp metal tips driven with low energy pulses from a few-cycle laser oscillator. We observe above-threshold photoemission with a photon order of up to 9. At a laser intensity of 2*10^11 W/cm^2 suppression of the lowest order peak occurs, indicating the onset of strong-field effects. We also observe peak shifting linearly with intensity with a slope of around -1.8eV / (10^12 W/cm^2). We attribute the magnitude of the laser field effects to field enhancement taking place at the tip's surface.

Markus Schenk; Michael Krüger; Peter Hommelhoff

2010-09-15T23:59:59.000Z

70

Large area quasi-free standing monolayer graphene on 3C-SiC(111)  

Science Conference Proceedings (OSTI)

Large scale, homogeneous quasi-free standing monolayer graphene is obtained on cubic silicon carbide, i.e., the 3C-SiC(111) surface, which represents an appealing and cost effective platform for graphene growth. The quasi-free monolayer is produced by intercalation of hydrogen under the interfacial, (6{radical}(3)x6{radical}(3))R30 deg.-reconstructed carbon layer. After intercalation, angle resolved photoemission spectroscopy reveals sharp linear {pi}-bands. The decoupling of graphene from the substrate is identified by x-ray photoemission spectroscopy and low energy electron diffraction. Atomic force microscopy and low energy electron microscopy demonstrate that homogeneous monolayer domains extend over areas of hundreds of square-micrometers.

Coletti, C. [Max-Planck-Institut fuer Festkoerperforschung, Heisenbergstr. 1, D-70569 Stuttgart (Germany); Center for Nanotechnology Innovation and NEST, Istituto Italiano di Tecnologia, Piazza San Silvestro 12, 56127 Pisa (Italy); Emtsev, K. V.; Starke, U. [Max-Planck-Institut fuer Festkoerperforschung, Heisenbergstr. 1, D-70569 Stuttgart (Germany); Zakharov, A. A. [MAX-Lab, Lund University, Box 118, Lund S-22100 (Sweden); Ouisse, T.; Chaussende, D. [Laboratoire des Materiaux et du Genie Physique-CNRS UMR5628--Grenoble INP, Minatec 3 parvis Louis Neel, BP 257, 38016 Grenoble (France)

2011-08-22T23:59:59.000Z

71

Charging of insulating and conducting dust grains by flowing plasma and photoemission  

E-Print Network (OSTI)

The charging of conducting or alternatively insulating dust grains in a supersonic plasma flow with a directed photon flux is studied by the particle-in-cell method. The electron emission modifies the surface charge distribution on a grain and in the surrounding plasma. The charge and potential distributions on and around a dust grain are studied for different photon fluxes and different angles of the incident unidirectional photons with respect to the plasma flow velocity vector. Continuous and pulsed radiations are considered. We show that photoemission allows controlling the charge on conducting grains, and discuss the charging of stationary and spinning insulating grains. Interactions between positively charged grains can be stronger than for negatively charged grains. The simulations are carried out in two spatial dimensions, treating ions and electrons as individual particles.

Miloch, W J; Pecseli, H L; Trulsen, J

2009-01-01T23:59:59.000Z

72

Thermal reactions of disilane on Si(100) studied by synchrotron-radiation photoemission  

SciTech Connect

H-terminated Si(100) surfaces were formed by saturation exposure of Si(100) to disilane at room temperature. Annealing these surfaces to progressively higher temperatures resulted in hydrogen desorption. This process, of basic importance to the growth of Si by atomic layer epitaxy using disilane, was studied by synchrotron-radiation photoemission. The Si 2[ital p] core-level line shape, the position of the Fermi level within the band gap, the work function, and the ionization potential were measured as a function of annealing temperature. These results revealed two steps in the thermal reaction preceding the recovery of the clean surface. The dihydride radicals on the surface are converted to monohydride radicals at 500--610 K, and the monohydride radicals decompose at 700--800 K.

Lin, D.; Miller, T.; Chiang, T. (Department of Physics and Materials Research Laboratory, University of Illinois at Urbana-Champaign, 1110 West Green Street, Urbana, Illinois 61801-3080 (United States)); Tsu, R.; Greene, J.E. (Department of Materials Science and Engineering, Coordinated Science Laboratory, and Materials Research Laboratory, University of Illinois at Urbana-Champaign, 1304 West Green Street, Urbana, Illinois 61801-3080 (United States))

1993-10-15T23:59:59.000Z

73

X-ray Imaging Workshop  

NLE Websites -- All DOE Office Websites (Extended Search)

Imaging and Spectro-microscopy: Imaging and Spectro-microscopy: the Present and the Future Stanford Synchrotron Radiation Laboratory October 8-9, 2002 Organizers: John Miao & Keith Hodgson A workshop on "X-ray Imaging and Spectro-microscopy: the Present and the Future" was held on October 8-9, 2002. This workshop, organized by John Miao (SSRL) and Keith Hodgson (SSRL) provided a forum to discuss the scientific applications of a variety of imaging and spectro-microscopic techniques, including photoemission electron microscopy (PEEM), angle resolved photoemission spectroscopy (ARPES), coherent diffraction imaging, x-ray microscopy, micro-tomography, holographic imaging, and x-ray micro-probe. Twelve invited speakers discussed the important scientific applications of these techniques, and also predicted the future scientific directions with the advance of instrumentation and x-ray sources. The workshop was well attended with over fifty registered attendees.

74

Atomic Spectroscopy Data Center  

Science Conference Proceedings (OSTI)

Atomic Spectroscopy Data Center. Summary: ... Atomic Spectroscopy Data Webpage. End Date: ongoing. Lead Organizational Unit: physlab. Contact. ...

2013-06-06T23:59:59.000Z

75

SURFACE SEGREGATION STUDIES OF SOFC CATHODES: COMBINING SOFT X-RAYS AND ELECTROCHEMICAL IMPEDENCE SPECTROSCOPY  

DOE Green Energy (OSTI)

A system to grow heteroepitaxial thin-films of solid oxide fuel cell (SOFC) cathodes on single crystal substrates was developed. The cathode composition investigated was 20% strontium-doped lanthanum manganite (LSM) grown by pulsed laser deposition (PLD) on single crystal (111) yttria-stabilized zirconia (YSZ) substrates. By combining electrochemical impedance spectroscopy (EIS) with x-ray photoemission spectroscopy (XPS) and x-ray absorption spectroscopy XAS measurements, we conclude that electrically driven cation migration away from the two-phase gas-cathode interface results in improved electrochemical performance. Our results provide support to the premise that the removal of surface passivating phases containing Sr2+ and Mn2+, which readily form at elevated temperatures even in O2 atmospheric pressures, is responsible for the improved cathodic performance upon application of a bias.

Miara, Lincoln J.; Piper, L.F.J.; Davis, Jacob N.; Saraf, Laxmikant V.; Kaspar, Tiffany C.; Basu, Soumendra; Smith, K. E.; Pal, Uday B.; Gopalan, Srikanth

2010-12-01T23:59:59.000Z

76

Time delay between photoemission from the 2p and 2s subshells of neon  

SciTech Connect

The R-matrix incorporating time (RMT) method is a method developed recently for solving the time-dependent Schroedinger equation for multielectron atomic systems exposed to intense short-pulse laser light. We have employed the RMT method to investigate the time delay in the photoemission of an electron liberated from a 2p orbital in a neon atom with respect to one released from a 2s orbital following absorption of an attosecond xuv pulse. Time delays due to xuv pulses in the range 76-105 eV are presented. For an xuv pulse at the experimentally relevant energy of 105.2 eV, we calculate the time delay to be 10.2{+-}1.3 attoseconds (as), somewhat larger than estimated by other theoretical calculations, but still a factor of 2 smaller than experiment. We repeated the calculation for a photon energy of 89.8 eV with a larger basis set capable of modeling correlated-electron dynamics within the neon atom and the residual Ne{sup +} ion. A time delay of 14.5{+-}1.5 as was observed, compared to a 16.7{+-}1.5 as result using a single-configuration representation of the residual Ne{sup +} ion.

Moore, L. R.; Lysaght, M. A.; Parker, J. S.; Hart, H. W. van der; Taylor, K. T. [Centre for Theoretical Atomic, Molecular and Optical Physics, Queen's University Belfast, Belfast BT7 1NN (United Kingdom)

2011-12-15T23:59:59.000Z

77

Awards  

NLE Websites -- All DOE Office Websites (Extended Search)

Awards Print Awards Print Recent awards given to ALS staff and users in recognition of their scientific and technical achievements. ALS users and staff are invited to send us information about recent awards by completing this form or by sending an email to This e-mail address is being protected from spambots. You need JavaScript enabled to view it . 2013 December In September, Shuyun Zhou, a previous ALS postdoctoral fellow, received "Outstanding Young Scholar Award" from Qiu Shi Science and Technology Foundation. Shuyun Zhou is currently an associate professor at the Department of Physics at Tsinghua University, Beijing. Before returning to her home university in 2012, she had built her track record from 10 years of research conducted at the ALS, initially as a Ph.D. student of UC Berkeley and ALS doctoral fellow, later as ALS postdoc fellow and project scientist from Materials Sciences Division. Her major achievements include electronic structure studies of graphene using angle-resolved photoemission spectroscopy, and ultrafast dynamic studies of localized electronic orderings in quantum materials using ultrafast time-resolved resonant X-ray scattering. While building her lab-based ultrafast time- and angle-resolved photoemission program at Tsinghua University, she has continued close collaboration with the ALS and recent progress has been made on the intriguing coupling between a topological insulator and a high temperature superconductor.

78

Awards  

NLE Websites -- All DOE Office Websites (Extended Search)

Awards Awards Awards Print Wednesday, 29 July 2009 00:00 Recent awards given to ALS staff and users in recognition of their scientific and technical achievements. ALS users and staff are invited to send us information about recent awards by completing this form or by sending an email to This e-mail address is being protected from spambots. You need JavaScript enabled to view it . 2013 December In September, Shuyun Zhou, a previous ALS postdoctoral fellow, received "Outstanding Young Scholar Award" from Qiu Shi Science and Technology Foundation. Shuyun Zhou is currently an associate professor at the Department of Physics at Tsinghua University, Beijing. Before returning to her home university in 2012, she had built her track record from 10 years of research conducted at the ALS, initially as a Ph.D. student of UC Berkeley and ALS doctoral fellow, later as ALS postdoc fellow and project scientist from Materials Sciences Division. Her major achievements include electronic structure studies of graphene using angle-resolved photoemission spectroscopy, and ultrafast dynamic studies of localized electronic orderings in quantum materials using ultrafast time-resolved resonant X-ray scattering. While building her lab-based ultrafast time- and angle-resolved photoemission program at Tsinghua University, she has continued close collaboration with the ALS and recent progress has been made on the intriguing coupling between a topological insulator and a high temperature superconductor.

79

Awards  

NLE Websites -- All DOE Office Websites (Extended Search)

Awards Print Awards Print Recent awards given to ALS staff and users in recognition of their scientific and technical achievements. ALS users and staff are invited to send us information about recent awards by completing this form or by sending an email to This e-mail address is being protected from spambots. You need JavaScript enabled to view it . 2013 December In September, Shuyun Zhou, a previous ALS postdoctoral fellow, received "Outstanding Young Scholar Award" from Qiu Shi Science and Technology Foundation. Shuyun Zhou is currently an associate professor at the Department of Physics at Tsinghua University, Beijing. Before returning to her home university in 2012, she had built her track record from 10 years of research conducted at the ALS, initially as a Ph.D. student of UC Berkeley and ALS doctoral fellow, later as ALS postdoc fellow and project scientist from Materials Sciences Division. Her major achievements include electronic structure studies of graphene using angle-resolved photoemission spectroscopy, and ultrafast dynamic studies of localized electronic orderings in quantum materials using ultrafast time-resolved resonant X-ray scattering. While building her lab-based ultrafast time- and angle-resolved photoemission program at Tsinghua University, she has continued close collaboration with the ALS and recent progress has been made on the intriguing coupling between a topological insulator and a high temperature superconductor.

80

In situ atomic layer deposition and synchrotron-radiation photoemission study of Al2O3 on pristine n-GaAs(0 0 1)-4×6 surface  

Science Conference Proceedings (OSTI)

This work presents the in situ reflection high-energy electron diffraction (RHEED), scanning tunneling microscopy (STM) and synchrotron-radiation photoemission studies for the morphological and interfacial chemical characterization of in situ atomic ... Keywords: Atomic layer deposition, GaAs, Molecular beam epitaxy, Synchrotron-radiation photoemission

Y. H. Chang; M. L. Huang; P. Chang; J. Y. Shen; B. R. Chen; C. L. Hsu; T. W. Pi; M. Hong; J. Kwo

2011-07-01T23:59:59.000Z

Note: This page contains sample records for the topic "angle-resolved photoemission spectroscopy" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


81

A search for spin-polarized photoemission from GaAs using light with orbital angular momentum  

Science Conference Proceedings (OSTI)

Laser light with photon energy near the bandgap of GaAs and with different amounts of orbital angular momentum was used to produce photoemission from unstrained GaAs. The degree of electron spin polarization was measured using a micro-Mott polarimeter and found to be consistent with zero with an upper limit of ~3% for light with up to ±5{bar h} of orbital angular momentum. In contrast, the degree of spin polarization was 32.32 ± 1.35% using circularly-polarized laser light at the same wavelength, which is typical of bulk GaAs.

Nathan Clayburn, James McCarter, Joan Dreiling, Bernard Poelker, Dominic Ryan, Timothy Gay

2013-01-01T23:59:59.000Z

82

Momentum-space Electronic Structures and Charge Orders of the High-temperature Superconductors Ca2?xNaxCuO2Cl2 and Bi2Sr2CaCu2O8+?  

SciTech Connect

We study the electronic structure of Ca{sub 2-x}Na{sub x}CuO{sub 2}Cl{sub 2} and Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8+{delta}} samples in a wide range of doping, using angle-resolved photoemission spectroscopy, with emphasis on the Fermi surface (FS) in the near antinodal region. The 'nesting wave vector,' i.e., the wave vector that connects two nearly flat pieces of the FS in the antinodal region, reveals a universal monotonic decrease in magnitude as a function of doping. Comparing our results to the charge order recently observed by scanning tunneling spectroscopy (STS), we conclude that the FS nesting and the charge order pattern seen in STS do not have a direct relationship. Therefore, the charge order likely arises due to strong-correlation physics rather than FS nesting physics.

Meng, J.Q.; Xu, Z.; Brunner, M.; Kim, K.-H.; Lee, H.-G.; Lee, S.-I.; Wen, J.S.; Gu, G.D.; Gweon, G.-H.

2011-08-24T23:59:59.000Z

83

Auger electron spectroscopy  

SciTech Connect

A review of Auger electron spectroscopy is presented. Methods, resolution, sensitivity, and uses are discussed. 30 references, 10 figures. (GHT)

Somorjai, G.A.

1980-12-01T23:59:59.000Z

84

Module to guide the expert use of x-ray photoelectron spectroscopy by corrosion scientists  

SciTech Connect

This contribution, to the potential development of data systems having some degree of 'expert' character for use in x-ray photoelectron spectroscopy (XPS), illustrates the manner in which models of 'Rules' might be developed by the user community. The field of corrosion science is taken as an example of one community of researchers who make regular use of XPS for well defined needs. These 'needs' are redefined as a series of Goals that have to be reached in order to characterize the surface in terms of layer sequences and the enrichment of given elements within them. Rules are written to allow a structured approach to achieve each Goal. A feature of this set of Rules is that they are designed expressly to allow automated interpretation of the survey scan. This approach is facilitated by the use of a recommendation that the survey spectrum be acquired as a series of accumulated scans instead of the usual approach of making a single scan through the spectrum. Repeat scans enable the information extracted by the operation of the Rules to be processed and displayed for information during the period that is normally used for the survey scan. It is intended that this information will inform the setting up of any subsequent high resolution scans and their interactive interpretation. It will also inform any future operations such as ion etching or angle-resolved measurements. In some cases, the information made available may be all that is required by the user and in this case the 'expert module' approach becomes particularly cost effective. The operation of the rules is illustrated throughout by an examination of data obtained for passivated stainless steel, giving a data set of measurements, typical of those made by corrosion scientists, that can be compared with the literature values obtained by more conventional XPS interpretation.

Castle, J. E. [Surface Analysis Laboratory, School of Engineering, Mail Drop H6, University of Surrey, Guildford GU2 7XH (United Kingdom)

2007-01-15T23:59:59.000Z

85

Deflection gating for time-resolved x-ray magnetic circular dichroism-photoemission electron microscopy using synchrotron radiation  

SciTech Connect

In this paper, we present a newly developed gating technique for a time-resolving photoemission microscope. The technique makes use of an electrostatic deflector within the microscope's electron optical system for fast switching between two electron-optical paths, one of which is used for imaging, while the other is blocked by an aperture stop. The system can be operated with a switching time of 20 ns and shows superior dark current rejection. We report on the application of this new gating technique to exploit the time structure in the injection bunch pattern of the synchrotron radiation source BESSY II at Helmholtz-Zentrum Berlin for time-resolved measurements in the picosecond regime.

Wiemann, C.; Kaiser, A. M.; Cramm, S. [Peter Gruenberg Institut PGI-6 'Electronic Properties', Research Centre Juelich, D-52425 Juelich (Germany); Schneider, C. M. [Peter Gruenberg Institut PGI-6 'Electronic Properties', Research Centre Juelich, D-52425 Juelich (Germany); Fakultaet fuer Physik and Center for Nanointegration Duisburg-Essen (CeNIDE), Universitaet Duisburg-Essen, D-47048 Duisburg (Germany)

2012-06-15T23:59:59.000Z

86

Laser Induced Spectroscopy  

INL’s Laser Induced Spectroscopy technology detects and measures the composition of a material or the molecules in the material. It traces the ...

87

arXiv:0805.0026v1[cond-mat.other]30Apr2008 Using photoemission spectroscopy to probe a strongly interacting Fermi gas  

E-Print Network (OSTI)

vector k. The black lines are the expected dispersion curve for an ideal Fermi gas. The white points and T Tc. The white line is a fit of the centers to a BCS-like dispersion. c Data for a gas on the BEC side to the centers using a quadratic dispersion. troscopy on the strongly interacting gas we extract the intensity

Jin, Deborah

88

Tuning of the Metal-Insulator Transition via Alkali Adsorption  

NLE Websites -- All DOE Office Websites (Extended Search)

Tuning of the Metal-Insulator Transition via Alkali Adsorption Print Tuning of the Metal-Insulator Transition via Alkali Adsorption Print Turning a material from an insulator to a metal, or vice versa, by light irradiation, exposure to electric or magnetic fields, or applying small changes in temperature, pressure, or doping-such intriguing control of a material's electronic properties is possible by exploiting strongly interacting or "correlated" electrons. Now a team of researchers from the University of Kiel in Germany and the ALS has found a novel, surprising way to continuously transform a layered metallic transition-metal compound, TaS2, into an insulator. Using angle-resolved photoemission spectroscopy (ARPES), they have demonstrated that adsorption of alkali atoms onto this material's surface gradually makes it more insulating, although in general, alkali adsorption should lead to more metallic behavior, as alkali atoms easily give away their loosely bound outermost electron.

89

First Observation of Plasmarons in Graphene  

NLE Websites -- All DOE Office Websites (Extended Search)

First Observation of Plasmarons in Graphene Print First Observation of Plasmarons in Graphene Print An international team of scientists performing angle-resolved photoemission spectroscopy (ARPES) experiments at ALS Beamline 7.0.1 have found that composite particles called plasmarons play a vital role in determining graphene's properties. A plasmaron consists of a charge carrier (electron or hole) coupled with a plasmon-an electron density wave. Although plasmarons were proposed theoretically in the late 1960s, and indirect evidence of them has been found, this work is the first observation of their distinct energy bands in graphene, or indeed in any material. The discovery may hasten the day when graphene can be used for "plasmonics" to build ultrafast computers-perhaps even room-temperature quantum computers-plus a wide range of other tools and applications.

90

Observation of a Macroscopically Quantum-Entangled Insulator  

NLE Websites -- All DOE Office Websites (Extended Search)

Observation of a Macroscopically Observation of a Macroscopically Quantum-Entangled Insulator Observation of a Macroscopically Quantum-Entangled Insulator Print Wednesday, 27 May 2009 00:00 It has recently been proposed that insulators with large band gaps and strong spin-orbit coupling can host a new phase of quantum matter called a topological insulator that is characterized by entangled wavefunctions. The proposal has now been realized by an international collaboration led by researchers from Princeton University who studied the electronic structure of insulating alloys of bismuth and antimony by means of angle-resolved photoemission spectroscopy (ARPES) and spin-resolved ARPES. Their results constitute the first direct experimental evidence of a topological insulator in nature that is fully quantum entangled. In the future, a detailed study of topological order and quantum entanglement using their method can potentially pave the way for fault-tolerant (topological) quantum computing.

91

ARPES Provides Direct Evidence of Spin-Wave Coupling  

NLE Websites -- All DOE Office Websites (Extended Search)

ARPES Provides Direct Evidence of Spin-Wave Coupling Print ARPES Provides Direct Evidence of Spin-Wave Coupling Print The electronic properties of a metal are determined by the dynamical behavior of its conduction electrons. Conventional band theory accounts for the interaction of the electrons with the static ion lattice. However, coupling to further microscopic degrees of freedom can alter the electron dynamics considerably. For example, "conventional" superconductivity emerges as a result of the electrons' interaction with lattice vibrations (phonons). In magnetic materials, coupling with spin waves (magnons) is also expected. Such interactions may contribute to high-temperature superconductivity in novel materials. Unfortunately, lattice vibrations and spin waves have similar energy scales, hindering detailed study. Researchers have taken a new approach in analyzing the electron bands of ferromagnetic iron. Angle-resolved photoemission spectroscopy (ARPES) provides direct spectroscopic evidence of altered electron mass and energy (quasiparticle formation) in a magnetic solid due to coupling with spin waves.

92

Observation of a Macroscopically Quantum-Entangled Insulator  

NLE Websites -- All DOE Office Websites (Extended Search)

Observation of a Macroscopically Quantum-Entangled Insulator Print Observation of a Macroscopically Quantum-Entangled Insulator Print It has recently been proposed that insulators with large band gaps and strong spin-orbit coupling can host a new phase of quantum matter called a topological insulator that is characterized by entangled wavefunctions. The proposal has now been realized by an international collaboration led by researchers from Princeton University who studied the electronic structure of insulating alloys of bismuth and antimony by means of angle-resolved photoemission spectroscopy (ARPES) and spin-resolved ARPES. Their results constitute the first direct experimental evidence of a topological insulator in nature that is fully quantum entangled. In the future, a detailed study of topological order and quantum entanglement using their method can potentially pave the way for fault-tolerant (topological) quantum computing.

93

ARPES Provides Direct Evidence of Spin-Wave Coupling  

NLE Websites -- All DOE Office Websites (Extended Search)

ARPES Provides Direct Evidence of Spin-Wave Coupling Print ARPES Provides Direct Evidence of Spin-Wave Coupling Print The electronic properties of a metal are determined by the dynamical behavior of its conduction electrons. Conventional band theory accounts for the interaction of the electrons with the static ion lattice. However, coupling to further microscopic degrees of freedom can alter the electron dynamics considerably. For example, "conventional" superconductivity emerges as a result of the electrons' interaction with lattice vibrations (phonons). In magnetic materials, coupling with spin waves (magnons) is also expected. Such interactions may contribute to high-temperature superconductivity in novel materials. Unfortunately, lattice vibrations and spin waves have similar energy scales, hindering detailed study. Researchers have taken a new approach in analyzing the electron bands of ferromagnetic iron. Angle-resolved photoemission spectroscopy (ARPES) provides direct spectroscopic evidence of altered electron mass and energy (quasiparticle formation) in a magnetic solid due to coupling with spin waves.

94

Observation of a Macroscopically Quantum-Entangled Insulator  

NLE Websites -- All DOE Office Websites (Extended Search)

Observation of a Macroscopically Quantum-Entangled Insulator Print Observation of a Macroscopically Quantum-Entangled Insulator Print It has recently been proposed that insulators with large band gaps and strong spin-orbit coupling can host a new phase of quantum matter called a topological insulator that is characterized by entangled wavefunctions. The proposal has now been realized by an international collaboration led by researchers from Princeton University who studied the electronic structure of insulating alloys of bismuth and antimony by means of angle-resolved photoemission spectroscopy (ARPES) and spin-resolved ARPES. Their results constitute the first direct experimental evidence of a topological insulator in nature that is fully quantum entangled. In the future, a detailed study of topological order and quantum entanglement using their method can potentially pave the way for fault-tolerant (topological) quantum computing.

95

Experimental Realization of a Three-Dimensional Topological Insulator, Bi 2Te3  

SciTech Connect

Three-dimensional topological insulators are a new state of quantum matter with a bulk gap and odd number of relativistic Dirac fermions on the surface. By investigating the surface state of Bi{sub 2}Te{sub 3} with angle-resolved photoemission spectroscopy, we demonstrate that the surface state consists of a single nondegenerate Dirac cone. Furthermore, with appropriate hole doping, the Fermi level can be tuned to intersect only the surface states, indicating a full energy gap for the bulk states. Our results establish that Bi{sub 2}Te{sub 3} is a simple model system for the three-dimensional topological insulator with a single Dirac cone on the surface. The large bulk gap of Bi{sub 2}Te{sub 3} also points to promising potential for high-temperature spintronics applications.

Siemons, W.

2010-02-24T23:59:59.000Z

96

Studies Bolster Promise of Topological Insulators  

NLE Websites -- All DOE Office Websites (Extended Search)

Studies Bolster Promise of Studies Bolster Promise of Topological Insulators Studies Bolster Promise of Topological Insulators Print Tuesday, 27 November 2012 00:00 A few years ago, a strange new material began to drive research in condensed-matter physics around the world. First theorized and then discovered by researchers at Berkeley Lab and their colleagues in other institutions, these "strong 3D topological insulators"-TIs for short-are seemingly mundane semiconductors with startling properties. Not only are they promising materials for energy-conserving electronic applications, they provide a fascinating medium for possibly observing still-theoretical particles that could play a major role in quantum computing. Two angle-resolved photoemission spectroscopy (ARPES) studies recently performed at ALS Beamline 12.0.1 improve the prospects for the practical application of TIs in advanced devices.

97

Influence of Topological Spin Fluctuations on Charge Transport  

NLE Websites -- All DOE Office Websites (Extended Search)

Influence of Topological Spin Fluctuations on Charge Transport Print Influence of Topological Spin Fluctuations on Charge Transport Print Layered transition metal oxides are the focus of intense research efforts because they might clarify the superconducting mechanism of cuprate high-temperature superconductors (HTSCs). A case in point is NaxCoO2 with x = 0.7, which is a parent compound for a family of cobaltites that exhibits superconductivity. This class of materials is also thought to be ideal for detecting the long-sought resonating valence bond (RVB) state of matter proposed by Philip Anderson of Princeton University in 1973. Researchers from Princeton University and ALS are the first to use angle-resolved photoemission spectroscopy (ARPES) to demonstrate the strongly electron correlated nature of this material and to provide evidence that charge transport is strongly influenced by topological spin frustration.

98

Studies Bolster Promise of Topological Insulators  

NLE Websites -- All DOE Office Websites (Extended Search)

Studies Bolster Promise of Topological Insulators Print Studies Bolster Promise of Topological Insulators Print A few years ago, a strange new material began to drive research in condensed-matter physics around the world. First theorized and then discovered by researchers at Berkeley Lab and their colleagues in other institutions, these "strong 3D topological insulators"-TIs for short-are seemingly mundane semiconductors with startling properties. Not only are they promising materials for energy-conserving electronic applications, they provide a fascinating medium for possibly observing still-theoretical particles that could play a major role in quantum computing. Two angle-resolved photoemission spectroscopy (ARPES) studies recently performed at ALS Beamline 12.0.1 improve the prospects for the practical application of TIs in advanced devices.

99

First Direct Observation of Spinons and Holons  

NLE Websites -- All DOE Office Websites (Extended Search)

First Direct Observation of Spinons and Holons Print First Direct Observation of Spinons and Holons Print Spin and charge are inseparable traits of an electron, but in one-dimensional solids, a 40-year-old theory predicts their separation into "collective" modes-as independent excitation quanta called spinons and holons. Angle-resolved photoemission spectroscopy (ARPES) should provide the most direct evidence of this spin-charge separation, as the single quasiparticle peak splits into a spinon-holon two-peak structure. However, despite extensive ARPES experiments, the unambiguous observation of the two-peak structure has remained elusive. Working at the ALS, a team of researchers from Korea, Japan, and the U.S. has now observed electron spin-charge separation in a one-dimensional solid. These results hold implications for future developments in several key areas of advanced technology, including high-temperature superconductors, nanowires, and spintronics.

100

Influence of Topological Spin Fluctuations on Charge Transport  

NLE Websites -- All DOE Office Websites (Extended Search)

Influence of Topological Spin Fluctuations on Charge Transport Print Influence of Topological Spin Fluctuations on Charge Transport Print Layered transition metal oxides are the focus of intense research efforts because they might clarify the superconducting mechanism of cuprate high-temperature superconductors (HTSCs). A case in point is NaxCoO2 with x = 0.7, which is a parent compound for a family of cobaltites that exhibits superconductivity. This class of materials is also thought to be ideal for detecting the long-sought resonating valence bond (RVB) state of matter proposed by Philip Anderson of Princeton University in 1973. Researchers from Princeton University and ALS are the first to use angle-resolved photoemission spectroscopy (ARPES) to demonstrate the strongly electron correlated nature of this material and to provide evidence that charge transport is strongly influenced by topological spin frustration.

Note: This page contains sample records for the topic "angle-resolved photoemission spectroscopy" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


101

Studies Bolster Promise of Topological Insulators  

NLE Websites -- All DOE Office Websites (Extended Search)

Studies Bolster Promise of Topological Insulators Print Studies Bolster Promise of Topological Insulators Print A few years ago, a strange new material began to drive research in condensed-matter physics around the world. First theorized and then discovered by researchers at Berkeley Lab and their colleagues in other institutions, these "strong 3D topological insulators"-TIs for short-are seemingly mundane semiconductors with startling properties. Not only are they promising materials for energy-conserving electronic applications, they provide a fascinating medium for possibly observing still-theoretical particles that could play a major role in quantum computing. Two angle-resolved photoemission spectroscopy (ARPES) studies recently performed at ALS Beamline 12.0.1 improve the prospects for the practical application of TIs in advanced devices.

102

First Direct Observation of Spinons and Holons  

NLE Websites -- All DOE Office Websites (Extended Search)

First Direct Observation of Spinons and Holons Print First Direct Observation of Spinons and Holons Print Spin and charge are inseparable traits of an electron, but in one-dimensional solids, a 40-year-old theory predicts their separation into "collective" modes-as independent excitation quanta called spinons and holons. Angle-resolved photoemission spectroscopy (ARPES) should provide the most direct evidence of this spin-charge separation, as the single quasiparticle peak splits into a spinon-holon two-peak structure. However, despite extensive ARPES experiments, the unambiguous observation of the two-peak structure has remained elusive. Working at the ALS, a team of researchers from Korea, Japan, and the U.S. has now observed electron spin-charge separation in a one-dimensional solid. These results hold implications for future developments in several key areas of advanced technology, including high-temperature superconductors, nanowires, and spintronics.

103

First Observation of Plasmarons in Graphene  

NLE Websites -- All DOE Office Websites (Extended Search)

First Observation of Plasmarons First Observation of Plasmarons in Graphene First Observation of Plasmarons in Graphene Print Wednesday, 30 June 2010 00:00 An international team of scientists performing angle-resolved photoemission spectroscopy (ARPES) experiments at ALS Beamline 7.0.1 have found that composite particles called plasmarons play a vital role in determining graphene's properties. A plasmaron consists of a charge carrier (electron or hole) coupled with a plasmon-an electron density wave. Although plasmarons were proposed theoretically in the late 1960s, and indirect evidence of them has been found, this work is the first observation of their distinct energy bands in graphene, or indeed in any material. The discovery may hasten the day when graphene can be used for "plasmonics" to build ultrafast computers-perhaps even room-temperature quantum computers-plus a wide range of other tools and applications.

104

First Observation of Plasmarons in Graphene  

NLE Websites -- All DOE Office Websites (Extended Search)

First Observation of Plasmarons in Graphene Print First Observation of Plasmarons in Graphene Print An international team of scientists performing angle-resolved photoemission spectroscopy (ARPES) experiments at ALS Beamline 7.0.1 have found that composite particles called plasmarons play a vital role in determining graphene's properties. A plasmaron consists of a charge carrier (electron or hole) coupled with a plasmon-an electron density wave. Although plasmarons were proposed theoretically in the late 1960s, and indirect evidence of them has been found, this work is the first observation of their distinct energy bands in graphene, or indeed in any material. The discovery may hasten the day when graphene can be used for "plasmonics" to build ultrafast computers-perhaps even room-temperature quantum computers-plus a wide range of other tools and applications.

105

Studies Bolster Promise of Topological Insulators  

NLE Websites -- All DOE Office Websites (Extended Search)

Studies Bolster Promise of Topological Insulators Print Studies Bolster Promise of Topological Insulators Print A few years ago, a strange new material began to drive research in condensed-matter physics around the world. First theorized and then discovered by researchers at Berkeley Lab and their colleagues in other institutions, these "strong 3D topological insulators"-TIs for short-are seemingly mundane semiconductors with startling properties. Not only are they promising materials for energy-conserving electronic applications, they provide a fascinating medium for possibly observing still-theoretical particles that could play a major role in quantum computing. Two angle-resolved photoemission spectroscopy (ARPES) studies recently performed at ALS Beamline 12.0.1 improve the prospects for the practical application of TIs in advanced devices.

106

Many-body interactions in quasi-freestanding graphene  

Science Conference Proceedings (OSTI)

The Landau-Fermi liquid picture for quasiparticles assumes that charge carriers are dressed by many-body interactions, forming one of the fundamental theories of solids. Whether this picture still holds for a semimetal such as graphene at the neutrality point, i.e., when the chemical potential coincides with the Dirac point energy, is one of the long-standing puzzles in this field. Here we present such a study in quasi-freestanding graphene by using high-resolution angle-resolved photoemission spectroscopy. We see the electron-electron and electron-phonon interactions go through substantial changes when the semimetallic regime is approached, including renormalizations due to strong electron-electron interactions with similarities to marginal Fermi liquid behavior. These findings set a new benchmark in our understanding of many-body physics in graphene and a variety of novel materials with Dirac fermions.

Siegel, David; Park, Cheol-Hwan; Hwang, Choongyu; Deslippe, Jack; Fedorov, Alexei; Louie, Steven; Lanzara, Alessandra

2011-06-03T23:59:59.000Z

107

From a Single-Band Metal to a High-Temperature Superconductor via Two Thermal Phase Transitions  

SciTech Connect

The nature of the pseudogap phase of cuprate high-temperature superconductors is one of the most important unsolved problems in condensed matter physics. We studied the commencement of the pseudogap state at temperature T* using three different techniques (angle-resolved photoemission spectroscopy, polar Kerr effect, and time-resolved reflectivity) on the same optimally-doped Bi2201 crystals. We observe the coincident onset at T* of a particle-hole asymmetric antinodal gap, a non-zero Kerr rotation, and a change in the relaxational dynamics, consistent with a phase transition. Upon further cooling, spectroscopic signatures of superconductivity begin to grow close to the superconducting transition temperature (T{sub c}), entangled in an energy-momentum dependent fashion with the pre-existing pseudogap features.

He, R.-H.; Hashimoto, M.; Karapetyan, H.; Koralek, J.D.; Hinton, J.P.; Testaud, J.P.; Nathan, V.; Yoshida, Y.; Yao, H.; Tanaka, K.; Meevasana, W.; Moore, R.G.; Lu, D.H.; Mo, S.-K.; Ishikado, M.; Eisaki, H.; Hussain, Z.; Devereaux, T.P.; Kivelson, S.A.; Orenstein, J.; Kapitulnik, A.

2011-11-08T23:59:59.000Z

108

The hierarchy of multiple many-body interaction scales in high-temperature superconductors  

Science Conference Proceedings (OSTI)

To date, angle-resolved photoemission spectroscopy has been successful in identifying energy scales of the many-body interactions in correlated materials, focused on binding energies of up to a few hundred meV below the Fermi energy. Here, at higher energy scale, we present improved experimental data from four families of high-T{sub c} superconductors over a wide doping range that reveal a hierarchy of many-body interaction scales focused on: the low energy anomaly ('kink') of 0.03-0.09eV, a high energy anomaly of 0.3-0.5eV, and an anomalous enhancement of the width of the LDA-based CuO{sub 2} band extending to energies of {approx} 2 eV. Besides their universal behavior over the families, we find that all of these three dispersion anomalies also show clear doping dependence over the doping range presented.

Meevasana, W.

2010-05-03T23:59:59.000Z

109

Fermi Surface Evolution Across Multiple Charge Density Wave Transitions in ErTe3  

Science Conference Proceedings (OSTI)

The Fermi surface (FS) of ErTe{sub 3} is investigated using angle-resolved photoemission spectroscopy (ARPES). Low temperature measurements reveal two incommensurate charge density wave (CDW) gaps created by perpendicular FS nesting vectors. A large {Delta}{sub 1} = 175 meV gap arising from a CDW with c* - q{sub CDW1} {approx} 0.70(0)c* is in good agreement with the expected value. A second, smaller {Delta}{sub 2} = 50 meV gap is due to a second CDW with a* - q{sub CDW2} {approx} 0.68(5)a*. The temperature dependence of the FS, the two gaps and possible interaction between the CDWs are examined.

Moore, R.G.; /SLAC, SSRL /Stanford U., Geballe Lab.; Brouet, V.; /Orsay, LPS; He, R.; /SLAC, SSRL /Stanford U., Geballe Lab.; Lu, D.H.; /SLAC, SSRL; Ru, N.; Chu, J.-H.; Fisher, I.R.; /Stanford U., Geballe Lab.; Shen, Z.-X.; /SLAC, SSRL /Stanford U., Geballe Lab.

2010-02-15T23:59:59.000Z

110

Unusual Layer-Dependent Charge Distribution, Collective Mode Coupling, and Superconductivity in Multilayer Cuprate Ba2Ca3Cu4O8F2  

SciTech Connect

Low energy ultrahigh momentum resolution angle resolved photoemission spectroscopy study on four-layer self-doped high T{sub c} superconductor Ba{sub 2}Ca{sub 3}Cu{sub 4}O{sub 8}F{sub 2} (F0234) revealed fine structure in the band dispersion, identifying the unconventional association of hole and electron doping with the inner and outer CuO{sub 2} layers, respectively. For the states originating from two inequivalent CuO{sub 2} layers, different energy scales are observed in dispersion kinks associated with the collective mode coupling, with the larger energy scale found in the electron (n-) doped state which also has stronger coupling strength. Given the earlier finding that the superconducting gap is substantially larger along the n-type Fermi surface, our observations connect the mode coupling energy and strength with magnitude of the pairing gap.

Chen, Yulin; /SLAC /Stanford U., Phys. Dept. /LBL, Berkeley; Iyo, Akira; /JRCAT, Tsukuba /Tsukuba Coll. Tech.; Yang, Wanli; /LBL, Berkeley; Ino, Akihiro; /Hiroshima U.; Arita, M.; /Hiroshima U.; Johnston, Steve; /SLAC /Stanford U., Phys. Dept.; Eisaki, Hiroshi; /JRCAT, Tsukuba /Tsukuba Coll. Tech.; Namatame, H.; /Hiroshima U.; Taniguchi, M.; /Hiroshima U.; Devereaux, Thomas P.; /SLAC /Stanford U., Phys. Dept.; Hussain, Zahid; /LBL, Berkeley; Shen, Z.-X.; /SLAC /Stanford U., Phys. Dept.

2011-08-12T23:59:59.000Z

111

Doping-Dependent Nodal Fermi Velocity in Bi-2212 Revealed by High-Resolution ARPES  

Science Conference Proceedings (OSTI)

The improved resolution of laser-based angle-resolved photoemission spectroscopy (ARPES) allows reliable access to fine structures in the spectrum. We present a systematic, doping-dependent study of a recently discovered low-energy kink in the nodal dispersion of Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8+{delta}} (Bi-2212), which demonstrates the ubiquity and robustness of this kink in underdoped Bi-2212. The renormalization of the nodal velocity due to this kink becomes stronger with underdoping, revealing that the nodal Fermi velocity is non-universal, in contrast to assumed phenomenology. This is used together with laser-ARPES measurements of the gap velocity, v{sub 2}, to resolve discrepancies with thermal conductivity measurements.

Vishik, I. M.

2011-08-19T23:59:59.000Z

112

First Observation of Plasmarons in Graphene  

NLE Websites -- All DOE Office Websites (Extended Search)

First Observation of Plasmarons in Graphene Print First Observation of Plasmarons in Graphene Print An international team of scientists performing angle-resolved photoemission spectroscopy (ARPES) experiments at ALS Beamline 7.0.1 have found that composite particles called plasmarons play a vital role in determining graphene's properties. A plasmaron consists of a charge carrier (electron or hole) coupled with a plasmon-an electron density wave. Although plasmarons were proposed theoretically in the late 1960s, and indirect evidence of them has been found, this work is the first observation of their distinct energy bands in graphene, or indeed in any material. The discovery may hasten the day when graphene can be used for "plasmonics" to build ultrafast computers-perhaps even room-temperature quantum computers-plus a wide range of other tools and applications.

113

First Direct Observation of Spinons and Holons  

NLE Websites -- All DOE Office Websites (Extended Search)

First Direct Observation of Spinons and Holons Print First Direct Observation of Spinons and Holons Print Spin and charge are inseparable traits of an electron, but in one-dimensional solids, a 40-year-old theory predicts their separation into "collective" modes-as independent excitation quanta called spinons and holons. Angle-resolved photoemission spectroscopy (ARPES) should provide the most direct evidence of this spin-charge separation, as the single quasiparticle peak splits into a spinon-holon two-peak structure. However, despite extensive ARPES experiments, the unambiguous observation of the two-peak structure has remained elusive. Working at the ALS, a team of researchers from Korea, Japan, and the U.S. has now observed electron spin-charge separation in a one-dimensional solid. These results hold implications for future developments in several key areas of advanced technology, including high-temperature superconductors, nanowires, and spintronics.

114

Influence of Topological Spin Fluctuations on Charge Transport  

NLE Websites -- All DOE Office Websites (Extended Search)

Influence of Topological Spin Fluctuations on Charge Transport Print Influence of Topological Spin Fluctuations on Charge Transport Print Layered transition metal oxides are the focus of intense research efforts because they might clarify the superconducting mechanism of cuprate high-temperature superconductors (HTSCs). A case in point is NaxCoO2 with x = 0.7, which is a parent compound for a family of cobaltites that exhibits superconductivity. This class of materials is also thought to be ideal for detecting the long-sought resonating valence bond (RVB) state of matter proposed by Philip Anderson of Princeton University in 1973. Researchers from Princeton University and ALS are the first to use angle-resolved photoemission spectroscopy (ARPES) to demonstrate the strongly electron correlated nature of this material and to provide evidence that charge transport is strongly influenced by topological spin frustration.

115

First Observation of Plasmarons in Graphene  

NLE Websites -- All DOE Office Websites (Extended Search)

First Observation of Plasmarons in Graphene Print First Observation of Plasmarons in Graphene Print An international team of scientists performing angle-resolved photoemission spectroscopy (ARPES) experiments at ALS Beamline 7.0.1 have found that composite particles called plasmarons play a vital role in determining graphene's properties. A plasmaron consists of a charge carrier (electron or hole) coupled with a plasmon-an electron density wave. Although plasmarons were proposed theoretically in the late 1960s, and indirect evidence of them has been found, this work is the first observation of their distinct energy bands in graphene, or indeed in any material. The discovery may hasten the day when graphene can be used for "plasmonics" to build ultrafast computers-perhaps even room-temperature quantum computers-plus a wide range of other tools and applications.

116

Reversible tuning of the surface state in a pseudobinary Bi2(Te-Se)3 topological insulator  

SciTech Connect

We use angle-resolved photoemission spectroscopy to study a nontrivial surface state in a pseudobinary Bi2Te2.8Se0.2 topological insulator. We show that, unlike previously studied binaries, this is an intrinsic topological insulator with the conduction bulk band residing well above the chemical potential. Our data indicate that under a good vacuum condition there are no significant aging effects for more than two weeks after cleaving. We also demonstrate that the shift of the Kramers point at low temperature is caused by UV-assisted absorption of molecular hydrogen. Our findings pave the way for applications of these materials in devices and present an easy scheme to tune their properties.

Jiang, Rui; Wang, Lin-Lin; Huang, Mianliang; Dhaka, Rajendra S.; Johnson, Duane D.; Lograsso, Thomas A.; Kaminski, Adam

2012-08-10T23:59:59.000Z

117

High Tc Superconductivity  

NLE Websites -- All DOE Office Websites (Extended Search)

by C. Kim (SSRL), D. H. Lu (Stanford), K. M. Shen (Stanford) and Z.-X. Shen (Stanford/SSRL) by C. Kim (SSRL), D. H. Lu (Stanford), K. M. Shen (Stanford) and Z.-X. Shen (Stanford/SSRL) Extensive research efforts to study the novel electronic properties of high-Tc superconductors and their related materials by angle-resolved photoemission spectroscopy at a recently commissioned Beam Line 5-4 (led by Z.-X. Shen) continue to be successful, producing many important results. These results, which are highlighted by five articles recently published in Physical Review Letters and one in Science, brought our understanding steps closer to solving the mystery of the high-Tc superconductivity. With the development of the latest generation of ultra-high resolution electron spectrometers in the past few years, the technique of angle resolved photoemission spectroscopy (ARPES) has recently experienced a renaissance. Nowhere is this revolution more evident than in the study of the high-temperature superconductors, which more than a decade after their discovery, continue to defy theoretical explanation. Recent ARPES experiments performed at Beam Line 5-4 have led to critical new discoveries about the fundamental nature of these mysterious superconductors and are now changing the way that the physics community views these materials. An excellent benchmark for the huge leap in detector resolution and technology is the recent work on Sr2RuO4. Although it belongs to a slightly different family than the high- temperature superconductors, its exotic superconducting mechanism (Tc = 1K) and complex electronic structure make it itself a fascinating material. In the past, due to poor resolutions, ARPES studies on this material were in disagreement with theory and other experimental techniques.

118

Animation of JILA Frequency Comb Spectroscopy Technique  

Science Conference Proceedings (OSTI)

Animation of JILA Frequency Comb Spectroscopy Technique. The new JILA "frequency comb spectroscopy" technique ...

2012-08-17T23:59:59.000Z

119

Photoemission in strongly correlated crystalline f-electron systems: A need for a new approach  

SciTech Connect

The unusual properties of heavy fermion (or heavy electron) materials have sparked an avalanche of research over the last two decades in order to understand the basic phenomena responsible for these properties. Photoelectron spectroscopy (often referred to as PES in the following sections), the most direct measurement of the electronic structure of a material, should in principle be able to shed considerable light on this matter. In general the distinction between a localized and a band-like state is trivially observed in band dispersion. Much of the past work was performed on poly-crystalline samples, scraped in-situ to expose a clean surface for PES. There have since been considerable advances both in the quality of specimens as well as experimental resolution, which raise questions regarding these conclusions. Much of the past work on poly-crystalline samples has been reported in several review articles, most notably Allen et al., and it is not necessary here to review those efforts again, with the exception of subsequent work performed at high resolution. The primary focus of the present review will be on new measurements obtained on single crystals, cleaved or prepared in situ and measured at high resolution, which seem to suggest that agreement with the GS and NCA approximations is less than perfect, and that perhaps the starting models need to be modified, or that even an entirely new approach is called for. Of the promising new models the Periodic Anderson Model is most closely related to the SIM. Indeed, at high temperatures it reverts to the SIM. However, the charge polaron model of Liu (1997) as well as the two-electron band model of Sheng and Cooper (1995) cannot yet be ruled out. Inasmuch as the bulk of the single crystal work was performed by the Los Alamos group, this review will draw heavily on those results. Moreover, since the GS and NCA approximations represent the most comprehensive and widely accepted treatment of heavy fermion PES, it is only natural that the authors primarily concern themselves with analysis of PES data in terms of these models, in order to thoroughly test their validity in light of the new data.

Arko, A.J.; Joyce, J.J.; Sarrao, J. [and others

1998-12-01T23:59:59.000Z

120

NIST Atomic Spectroscopy Data Center  

Science Conference Proceedings (OSTI)

Atomic Spectroscopy Data Center. ... Responds to user requests for data, literature references, and technical information. ...

2011-11-29T23:59:59.000Z

Note: This page contains sample records for the topic "angle-resolved photoemission spectroscopy" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


121

EMSL: Capabilities: Spectroscopy and Diffraction  

NLE Websites -- All DOE Office Websites (Extended Search)

Spectroscopy and Diffraction Spectroscopy and Diffraction Additional Information Meet the Spectroscopy and Diffraction Experts Related EMSL User Projects Spectroscopy and Diffraction Tools are Applied to all Science Themes Tutorial: XPS Tools for Surface Analysis Spectroscopy and Diffraction brochure EMSL's suite of spectroscopy and diffraction instruments allows users to study solid-, liquid-, and gas-phase sample structure and composition with remarkable resolution. Ideal for integrated studies, spectrometers and diffractometers are easily coupled with EMSL's computational and modeling capabilities, allowing users to apply a multifaceted research approach for experimental data interpretation and gain fundamental understanding of scientific problems. At EMSL, spectroscopy and diffraction instruments are

122

Synchronization and Characterization of an Ultra-Short Laser for Photoemission and Electron-Beam Diagnostics Studies at a Radio Frequency Photoinjector  

SciTech Connect

A commercially-available titanium-sapphire laser system has recently been installed at the Fermilab A0 photoinjector laboratory in support of photoemission and electron beam diagnostics studies. The laser system is synchronized to both the 1.3-GHz master oscillator and a 1-Hz signal use to trigger the radiofrequency system and instrumentation acquisition. The synchronization scheme and performance are detailed. Long-term temporal and intensity drifts are identified and actively suppressed to within 1 ps and 1.5%, respectively. Measurement and optimization of the laser's temporal profile are accomplished using frequency-resolved optical gating.

Maxwell, Timothy; Ruan, Jinhao; Piot, Philippe; Lumpkin, Alex

2012-03-01T23:59:59.000Z

123

2008 Vibrational Spectroscopy  

SciTech Connect

The conference focuses on using vibrational spectroscopy to probe structure and dynamics of molecules in gases, liquids, and interfaces. The goal is to bring together a collection of researchers who share common interests and who will gain from discussing work at the forefront of several connected areas. The intent is to emphasize the insights and understanding that studies of vibrations provide about a variety of systems.

Philip J. Reid

2009-09-21T23:59:59.000Z

124

Ultrahigh vacuum sample mount for x-ray photoelectron spectroscopy up to very high temperature (150-1400 K)  

SciTech Connect

Spectroscopic studies are rarely performed at very high temperature, especially when combined with light from a synchrotron source. Demanding conditions of maintaining ultrahigh vacuum (UHV) during heating, together with the typically brief access to beam time at multiuser synchrotron end stations, may contribute to some of the reasons for the difficulty of such experiments. Consequently, a large number of materials with interesting properties and industrial applications at high temperature remain unexplored. The authors describe here a simple portable sample mount assembly that can be easily utilized at a beamline, with potential utility for a variety of spectroscopic measurements requiring elevated temperatures and an UHV environment. In the specific application described here, the authors use a resistive cartridge heater interfaced with a standard manipulator previously designed for cooling by liquid nitrogen with an UHV chamber and a cylindrical mirror analyzer for x-ray photoemission spectroscopy (XPS) [also known as electron spectroscopy for chemical analysis (ESCA)] at the Synchrotron Radiation Center in Stoughton, WI. The heater cartridge required only modest power to reach target temperatures using an open-loop temperature control. Finally, the authors describe the measurements of XPS (ESCA) and total-electron yield x-ray absorption spectroscopy on nanopowders and on single crystals grown by them. They emphasize the simplicity of the setup, which they believe would be of interest to groups performing measurements at large facilities, where access and time are both limited.

Williamsen, Mark S.; Ray, Shishir K.; Zou Ying; Dudek, John A.; Sen, Somaditya; Bissen, Mark; Kretsch, Laura; Palkar, Vaijayanti R.; Onellion, Marshall F.; Guptasarma, Prasenjit [Department of Physics, University of Wisconsin-Milwaukee, 1900 E. Kenwood Blvd., Milwaukee, Wisconsin 53211 (United States); Synchrotron Radiation Center, 3731 Schneider Dr., Stoughton, Wisconsin 53589 (United States); Department of Electrical Engineering, Indian Institute of Technology Bombay, Mumbai 400076 (India); Department of Physics, University of Wisconsin--Madison, 1150 University Ave., Madison, Wisconsin 53706 (United States); Department of Physics, University of Wisconsin-Milwaukee, 1900 E. Kenwood Blvd., Milwaukee, Wisconsin 53211 (United States)

2011-05-15T23:59:59.000Z

125

NIST State-resolved Biomolecular Spectroscopies  

Science Conference Proceedings (OSTI)

State-resolved Spectroscopy of Biomolecules. Summary: ... For examples, see State-resolved terahertz spectroscopy of biomolecules. ...

2012-10-18T23:59:59.000Z

126

Unraveling EXAFS spectroscopy  

SciTech Connect

The past several years have witnessed the emergence of Extended X-ray Absorption Fine Structure (EXAFS) spectroscopy from an esoteric technique to a widely available structural spectroscopic tool. Several in-depth review articles and books are available on the subject, but some aspects of theory or data reduction may be beyond the scope or need of the average chemist. In this article the authors will try to reduce the mystique surrounding EXAFS and clarify the terminology and concepts in the EXAFS literature. They will concentrate primarily on theory and data analysis and conclude with a few applications.

Fay, M.J.; Proctor, A.; Hoffman, D.P.; Hercules, D.M

1988-11-01T23:59:59.000Z

127

Charmonium and Light Meson Spectroscopy  

E-Print Network (OSTI)

This talk reviews recent experimental results on selected topics in the spectroscopy of charmonia, charmonium-like states and light mesons.

Kai Zhu

2012-12-10T23:59:59.000Z

128

NIST: Atomic Spectroscopy Group - Homepage  

Science Conference Proceedings (OSTI)

... The program in atomic spectroscopy at NIST provides accurate reference data on spectral lines and energy levels for a wide variety of important ...

2013-07-31T23:59:59.000Z

129

Growth and structure of water on SiO2 films on Si investigated byKelvin probe microscopy and in situ X-ray Spectroscopies  

SciTech Connect

The growth of water on thin SiO{sub 2} films on Si wafers at vapor pressures between 1.5 and 4 torr and temperatures between -10 and 21 C has been studied in situ using Kelvin Probe Microscopy and X-ray photoemission and absorption spectroscopies. From 0 to 75% relative humidity (RH) water adsorbs forming a uniform film 4-5 layers thick. The surface potential increases in that RH range by about 400 mV and remains constant upon further increase of the RH. Above 75% RH the water film grows rapidly, reaching 6-7 monolayers at around 90% RH and forming a macroscopic drop near 100%. The O K-edge near-edge X-ray absorption spectrum around 75% RH is similar to that of liquid water (imperfect H-bonding coordination) at temperatures above 0 C and ice-like below 0 C.

Verdaguer, A.; Weis, C.; Oncins, G.; Ketteler, G.; Bluhm, H.; Salmeron, M.

2007-06-14T23:59:59.000Z

130

Spectroscopy of Solar Neutrinos  

E-Print Network (OSTI)

In the last years, liquid-scintillator detectors have opened a new window for the observation of low-energetic astrophysical neutrino sources. In 2007, the solar neutrino experiment Borexino began its data-taking in the Gran Sasso underground laboratory. High energy resolution and excellent radioactive background conditions in the detector allow the first-time spectroscopic measurement of solar neutrinos in the sub-MeV energy regime. The experimental results of the Beryllium-7 neutrino flux measurements as well as the prospects for the detection of solar Boron-8, pep and CNO neutrinos are presented in the context of the currently discussed ambiguities in solar metallicity. In addition, the potential of the future SNO+ and LENA experiments for high-precision solar neutrino spectroscopy will be outlined.

Michael Wurm; Franz von Feilitzsch; Marianne Goeger-Neff; Tobias Lachenmaier; Timo Lewke; Quirin Meindl; Randoplh Moellenberg; Lothar Oberauer; Walter Potzel; Marc Tippmann; Christoph Traunsteiner; Juergen Winter

2010-04-06T23:59:59.000Z

131

Plasmon Dispersion in Two-dimensional Charge-Sheets.  

E-Print Network (OSTI)

??The dispersion of sheet plasmons in two-dimensional electron systems was investigated in an in-situ ultra high vacuum environment by angle-resolved high-resolution electron-energy-loss spectroscopy (HREELS). In… (more)

Liu, Yu

2009-01-01T23:59:59.000Z

132

Hadron Spectroscopy in COMPASS  

E-Print Network (OSTI)

The COmmon Muon and Proton Apparatus for Structure and Spectroscopy (COMPASS) is a multi-purpose fixed-target experiment at the CERN Super Proton Synchrotron (SPS) aimed at studying the structure and spectrum of hadrons. In the naive Constituent Quark Model (CQM) mesons are bound states of quarks and antiquarks. QCD, however, predict the existence of hadrons beyond the CQM with exotic properties interpreted as excited glue (hybrids) or even pure gluonic bound states (glueballs). One main goal of COMPASS is to search for these states. Particularly interesting are so called spin-exotic mesons which have J^{PC} quantum numbers forbidden for ordinary q\\bar{q} states. Its large acceptance, high resolution, and high-rate capability make the COMPASS experiment an excellent device to study the spectrum of light-quark mesons in diffractive and central production reactions up to masses of about 2.5 GeV. COMPASS is able to measure final states with charged as well as neutral particles, so that resonances can be studied in different reactions and decay channels. During 2008 and 2009 COMPASS acquired large data samples using negative and positive secondary hadron beams on lH_2, Ni, and Pb targets. The presented overview of the first results from this data set focuses in particular on the search for spin-exotic mesons in diffractively produced \\pi^-\\pi^+\\pi^-, \\eta\\pi, \\eta'\\pi, and \\pi^-\\pi^+\\pi^-\\pi^+\\pi^- final states and the analysis of central-production of \\pi^+\\pi^- pairs in order to study glueball candidates in the scalar sector.

Boris Grube; for the COMPASS Collaboration

2013-01-31T23:59:59.000Z

133

Ring resonant cavities for spectroscopy  

DOE Patents (OSTI)

Ring-shaped resonant cavities for spectroscopy allow a reduction in optical feedback to the light source, and provide information on the interaction of both s- and p-polarized light with samples. A laser light source is locked to a single cavity mode. An intracavity acousto-optic modulator may be used to couple light into the cavity. The cavity geometry is particularly useful for Cavity Ring-Down Spectroscopy (CRDS). 6 figs.

Zare, R.N.; Martin, J.; Paldus, B.A.; Xie, J.

1999-06-15T23:59:59.000Z

134

Suspension stirrer for NMR spectroscopy  

DOE Patents (OSTI)

This invention relates to nuclear magnetic resonance (NMR) spectroscopy and, more particularly, to the application of NMR spectroscopy to cell culture samples. A perfusion treatment system maintains microenvironmental conditions about cell spheroids during nuclear magnetic resonance (NMR) examination. A non-magnetic stirring assembly is inserted within a conventional NMR tube to continuously and uniformly supply a perfusate adjacent the spheroids. The perfusate is circulated during the spheroid stirring to maintain known perfusion conditions and eliminate artifacts from the NMR data. 4 figs.

Freyer, J.P; Coulter, J.R.

1990-12-02T23:59:59.000Z

135

Test 4, "NMR Spectroscopy", Chem416, FS93, Dr. Glaser --1 --Chemistry 416 "Spectroscopy"Chemistry 416 "Spectroscopy"  

E-Print Network (OSTI)

Test 4, "NMR Spectroscopy", Chem416, FS93, Dr. Glaser -- 1 -- Chemistry 416 "Spectroscopy "Take Home" Examination "NMR Spectroscopy" Hand-out: Wednesday, December 1, 1993 Collect: Friday Question 4 (13C Inc. Sys.) 20 Total 100 #12;Test 4, "NMR Spectroscopy", Chem416, FS93, Dr. Glaser -- 2

Glaser, Rainer

136

Investigating Ultrasonic Diffraction Grating Spectroscopy and ...  

Investigating Ultrasonic Diffraction Grating Spectroscopy and Reflection Techniques for Characterization Slurry Properties Investigating Ultrasonic Diffraction Grating

137

Spectroscopy (XSD) | Advanced Photon Source  

NLE Websites -- All DOE Office Websites (Extended Search)

Useful Links Useful Links Spectroscopy Group (X-ray Science Division) The Spectroscopy Group operates the Sector-20 bending magnet (BM) and insertion device (ID) beamlines, and the bending magnet beamline at Sector-9. Beamlines 20-ID (Undulator A) Supported Techniques ·X-ray absorption fine structure (XAFS) ·Surface Diffraction ·X-ray Raman Scattering ·Resonant X-ray Emission Spectroscopy ·Micro-XAFS ·Confocal X-ray microscopy ·Micro-fluorescence ·Micro-XRD Discipline ·Material Science ·Environmental Science ·Chemistry Click [20-ID] under "Beamlines" above for technical information 20-BM Supported Techniques X-ray absorption fine structure (XAFS) Micro-fluorescence Micro-XAFS Micro-diffraction Discipline ·Material Science ·Environmental Science ·Chemistry Click [20-BM] under "Beamlines" above for technical information

138

Quantum spectroscopy of plasmonic nanostructures  

E-Print Network (OSTI)

We use frequency entangled photons, generated via spontaneous parametric down conversion, to measure the broadband spectral response of an array of gold nanoparticles exhibiting Fano-type plasmon resonance. Refractive index sensing of a liquid is performed by measuring the shift of the array resonance. This method is robust in excessively noisy conditions compared with conventional broadband transmission spectroscopy. Detection of a refractive index change is demonstrated with a noise level 70 times higher than the signal, which is shown to be inaccessible with the conventional transmission spectroscopy. Use of low photon fluxes makes this method suitable for measurements of photosensitive bio-samples and chemical substances.

Dmitry A. Kalashnikov; Zhenying Pan; Arseniy I. Kuznetsov; Leonid A. Krivitsky

2013-12-11T23:59:59.000Z

139

Environmental Spectroscopy and Biogeochemistry Facility  

NLE Websites -- All DOE Office Websites (Extended Search)

ES&B Overview ES&B Overview Section 2-2-1 Environmental Spectroscopy and Biogeochemistry Facility The Environmental Spectroscopy and Biogeochemistry (ES&B) Facility focuses on environ- mental molecular science and application of the fundamental concepts of physical chemistry to the study of chemical reactions in heterogeneous natural materials, with an emphasis on soil and subsurface systems. The ES&B Facility staff, along with other Pacific Northwest National Laboratory (PNNL) staff, form a multidisciplinary research team with expertise in chemistry, mineral physics, geochemistry, soil chemistry, microbiology, hydrology, and environmental engineering. Capabilities Capabilities are available for materials characterization, aqueous- and solid-phase speciation

140

X-ray Absorption Spectroscopy  

SciTech Connect

This review gives a brief description of the theory and application of X-ray absorption spectroscopy, both X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS), especially, pertaining to photosynthesis. The advantages and limitations of the methods are discussed. Recent advances in extended EXAFS and polarized EXAFS using oriented membranes and single crystals are explained. Developments in theory in understanding the XANES spectra are described. The application of X-ray absorption spectroscopy to the study of the Mn4Ca cluster in Photosystem II is presented.

Yano, Junko; Yachandra, Vittal K.

2009-07-09T23:59:59.000Z

Note: This page contains sample records for the topic "angle-resolved photoemission spectroscopy" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


141

Spectroscopy of transient neutral species via negative ion photoelectron spectroscopy  

SciTech Connect

Negative ion photoelectron spectroscopy has been used to study two types of transient neutral species: bound free radicals (NO{sub 2} and NO{sub 3}) and unstable neutral species ((IHI) and (FH{sub 2})). The negative ion time-of-flight photoelectron spectrometer used for these experiments is described in detail.

Weaver, A.

1991-12-01T23:59:59.000Z

142

Spectroscopy of transient neutral species via negative ion photoelectron spectroscopy  

Science Conference Proceedings (OSTI)

Negative ion photoelectron spectroscopy has been used to study two types of transient neutral species: bound free radicals (NO{sub 2} and NO{sub 3}) and unstable neutral species ([IHI] and [FH{sub 2}]). The negative ion time-of-flight photoelectron spectrometer used for these experiments is described in detail.

Weaver, A.

1991-12-01T23:59:59.000Z

143

Diagnosing breast cancer using diffuse reflectance spectroscopy and intrinsic fluorescence spectroscopy  

E-Print Network (OSTI)

Using diffuse reflectance spectroscopy and intrinsic fluorescence spectroscopy, we have developed an algorithm that successfully classifies normal breast tissue, fibrocystic change, fibroadenoma, and infiltrating ductal ...

Fitzmaurice, Maryann

144

Ramsey spectroscopy with squeezed light  

E-Print Network (OSTI)

Traditional Ramsey spectroscopy has the frequency resolution $2\\pi/T$, where $T$ is the time separation between two light fields. Using squeezed states and two-atom excitation joint detection, we present a new scheme achieving a higher resolution $\\pi/T$. We use two mode squeezed light which exhibits strong entanglement.

Qu, Kenan

2013-01-01T23:59:59.000Z

145

DEVELOPMENTS IN HEAVY QUARKONIUM SPECTROSCOPY  

E-Print Network (OSTI)

­ 1­ DEVELOPMENTS IN HEAVY QUARKONIUM SPECTROSCOPY Written May 2012 by S. Eidelman (Budker Inst. Navas (Univ. Granada), and C. Patrignani (Univ. Genova, INFN). A golden age for heavy quarkonium physics at HERA and the Tevatron matured; and heavy-ion collisions at RHIC opened a window on the deconfinement

146

NMR Spectroscopy Protein-NMR  

E-Print Network (OSTI)

Keywords NMR Spectroscopy Protein-NMR Physical Organic Chemistry » Prof. Dr. Stefan Berger The research group of Prof. Dr. Stefan Berger focuses its work on: 1. Protein-NMR for the genera- tion of Protein-Structures. This includes application of all mod- ern 3D NMR pulse sequences for fully 15 N and 13

Schüler, Axel

147

Effects of hydrogen on the dynamics of the Mo{sub 0.95}Re{sub 0.05}(ll0) surface  

DOE Green Energy (OSTI)

The effect of adsorbed H on the Mo{sub 0.95}Re{sub 0.05}(110) surface has been investigated. Results obtained from low-energy electron diffraction, high-resolution electron energy loss spectroscopy (HREELS) and angle-resolved ultra-violet photoemission spectroscopy are presented. A (2{times}2) LEED pattern is observed for H coverages around {Theta} {approximately} 0.6 ML and is attributed to reconstruction of the substrate. At higher coverages, a (1{times}1) pattern is observed. Two peaks are observed at loss energies of 99 and 153 meV in the HREELS spectra for the H-saturated Mo{sub 0. 95}Re{sub 0.05}(110) surface. Both peaks show an isotopic shift, confirming that they are due to hydrogen vibrational modes and a quasi-trigonal adsorption site is consistent with these observations. A two dimensional Fermi surface was determined for the H-saturated Mo{sub 0.95}Re{sub 0.05}(110) surface. The Fermi-surface nesting vector was observed at the place where theoretical calculations predict it to occur on H-saturated Mo(110) and it may be related to the phonon anomaly observed for this surface.

Okada, M; Plummer, E.W. [Tennessee Univ., Knoxville, TN (United States)]|[Oak Ridge National Lab., TN (United States); Baddorf, A.P.; Zehner, D.M.

1995-08-01T23:59:59.000Z

148

New JILA Technique Reveals Hidden Properties of Ultracold ...  

Science Conference Proceedings (OSTI)

... Photoemission spectroscopy is particularly powerful in revealing details of the pairing of electrons in high-temperature superconductors, which are ...

2010-10-05T23:59:59.000Z

149

Raman Spectroscopy for Experimental Investigation of Microscale ...  

Science Conference Proceedings (OSTI)

New Saccharification Process of Cellulosic Biomass by Microwave Irradiation · Novel Lamination Method for Large Armor Panels · Raman Spectroscopy for ...

150

Light Hadron Spectroscopy and Charmonium  

E-Print Network (OSTI)

During the last few years there has been a renaissance in charm and charmonium spectroscopy with higher precision measurements at the $\\psi^{'}$ and $\\psi(3770)$ coming from BESII and CLEOc and many new discoveries coming from B-factories. In this paper, I review some new results on "classical" charmonium and $e^+ e^- \\to$ hadrons using B-factory Initial State Radiation and two photon events.

Frederick A. Harris

2008-10-17T23:59:59.000Z

151

spectroscopy  

Science Conference Proceedings (OSTI)

... of crystal spectrometers where the energy dispersion is polarization selective. ... by observing forbidden (M1) transitions within the ground term of ...

2010-12-07T23:59:59.000Z

152

Nematic State of Pnictides Stabilized by Interplay between Spin, Orbital, and Lattice Degrees of Freedom  

Science Conference Proceedings (OSTI)

The nematic state of the iron-based superconductors is studied in the undoped limit of the three-orbital (xz, yz, xy) spin-fermion model via the introduction of lattice degrees of freedom. Monte Carlo simulations show that in order to stabilize the experimentally observed lattice distortion and nematic order, and to reproduce photoemission experiments, both the spin-lattice and orbital-lattice couplings are needed. The interplay between their respective coupling strengths regulates the separation between the structural and Ne el transition temperatures. Experimental results for the temperature dependence of the resistivity anisotropy and the angle-resolved photoemission orbital spectral weight are reproduced by the present numerical simulations.

Liang, Shuhua [ORNL; Moreo, Adriana [ORNL; Dagotto, Elbio R [ORNL

2013-01-01T23:59:59.000Z

153

Simultaneous beta and gamma spectroscopy  

DOE Patents (OSTI)

A phoswich radiation detector for simultaneous spectroscopy of beta rays and gamma rays includes three scintillators with different decay time characteristics. Two of the three scintillators are used for beta detection and the third scintillator is used for gamma detection. A pulse induced by an interaction of radiation with the detector is digitally analyzed to classify the type of event as beta, gamma, or unknown. A pulse is classified as a beta event if the pulse originated from just the first scintillator alone or from just the first and the second scintillator. A pulse from just the third scintillator is recorded as gamma event. Other pulses are rejected as unknown events.

Farsoni, Abdollah T. (Corvallis, OR); Hamby, David M. (Corvallis, OR)

2010-03-23T23:59:59.000Z

154

Optical sensing based on wavelength modulation spectroscopy  

DOE Patents (OSTI)

Techniques, apparatus and systems for using Wavelength Modulation Spectroscopy measurements to optically monitor gas media such as gases in gas combustion chambers.

Buckley, Steven G. (Redmond, WA); Gharavi, Mohammadreza (Tehran, IR); Borchers; Marco (Berlin, DE)

2011-06-28T23:59:59.000Z

155

NIST Ultrafast Terahertz Spectroscopy and Imaging  

Science Conference Proceedings (OSTI)

... THz spectrometer for spectral determinations of samples (0.2 to 10 THz) and transient spectroscopy of bimolecular, photovoltaic, and materials ...

2013-09-20T23:59:59.000Z

156

Standoff Spectroscopy Using a Conditioned Target ...  

... and households Patent Charles W. Van Neste, Marissa E. Morales-Rodriguez, Lawrence R. Senesac, and Thomas G. Thundat, Standoff Spectroscopy Using ...

157

Laser-Induced Breakdown Spectroscopy Research Facility  

LIBS Research User Facility is focused on collaborative research in laser spark spectroscopy, laser ablation, and the development of techniques for application to ...

158

High-Efficiency Neutron Detection and Spectroscopy  

Science Conference Proceedings (OSTI)

High-Efficiency Neutron Detection and Spectroscopy. ... such as searches for WIMP dark matter, neutrinoless double beta decay, and solar neutrinos. ...

2013-07-22T23:59:59.000Z

159

Electron-State Hybridization in Heavy-Fermion Systems  

NLE Websites -- All DOE Office Websites (Extended Search)

Electron-State Hybridization in Heavy-Fermion Systems Print Electron-State Hybridization in Heavy-Fermion Systems Print Heavy-fermion systems are characterized by electrons with extremely large effective masses. The corresponding heavy-electron "quasiparticle" states are close to the Fermi energy and govern the thermodynamic, transport, and, in part, magnetic properties of these materials. In the case of rare-earth compounds, the quasiparticle states arise from the interactions (hybridization) of valence states with strongly localized 4f states. The question as to whether it is sufficient to treat the f states as localized impurities (single-impurity Anderson model) or whether the periodic crystal symmetry must be considered (periodic Anderson model) has been the subject of extensive debate. An international team of researchers from Germany, Ukraine, India, and the U.S. has performed angle-resolved photoemission spectroscopy (ARPES) studies of the heavy-fermion system YbIr2Si2. The results show a strong momentum (directional) dependence of the hybridization that clearly rules out the single-impurity model in favor of the lattice model.

160

First Direct Evidence of Dirac Fermions in Graphite  

NLE Websites -- All DOE Office Websites (Extended Search)

Direct Evidence of Dirac Direct Evidence of Dirac Fermions in Graphite First Direct Evidence of Dirac Fermions in Graphite Print Wednesday, 27 June 2007 00:00 The recent surge of interest in the electronic properties of graphene-that is, isolated layers of graphite just one atomic layer thick-has largely been driven by the discovery that electron mobility in graphene is ten times higher than in commercial-grade silicon, raising the possibility of high-efficiency, low-power, carbon-based electronics. Scientists attribute graphene's surprising current capacity (as well as a number of even stranger phenomena) to the presence of charge carriers that behave as if they are massless, "relativistic" quasiparticles called Dirac fermions. Harnessing these quasiparticles in real-world carbon-based devices, however, requires a deeper knowledge of their behavior under less-than-ideal circumstances, such as around defects, at edges, or in three dimensions-in other words, in graphite. At the ALS, a team of researchers using angle-resolved photoemission spectroscopy (ARPES) have now produced the first direct evidence of massless Dirac fermions in graphite coexisting with quasiparticles of finite effective mass and defect-induced localized states.

Note: This page contains sample records for the topic "angle-resolved photoemission spectroscopy" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


161

Electron-State Hybridization in Heavy-Fermion Systems  

NLE Websites -- All DOE Office Websites (Extended Search)

Electron-State Hybridization in Electron-State Hybridization in Heavy-Fermion Systems Electron-State Hybridization in Heavy-Fermion Systems Print Wednesday, 27 September 2006 00:00 Heavy-fermion systems are characterized by electrons with extremely large effective masses. The corresponding heavy-electron "quasiparticle" states are close to the Fermi energy and govern the thermodynamic, transport, and, in part, magnetic properties of these materials. In the case of rare-earth compounds, the quasiparticle states arise from the interactions (hybridization) of valence states with strongly localized 4f states. The question as to whether it is sufficient to treat the f states as localized impurities (single-impurity Anderson model) or whether the periodic crystal symmetry must be considered (periodic Anderson model) has been the subject of extensive debate. An international team of researchers from Germany, Ukraine, India, and the U.S. has performed angle-resolved photoemission spectroscopy (ARPES) studies of the heavy-fermion system YbIr2Si2. The results show a strong momentum (directional) dependence of the hybridization that clearly rules out the single-impurity model in favor of the lattice model.

162

Superconducting Topological Insulators  

NLE Websites -- All DOE Office Websites (Extended Search)

Superconducting Topological Insulators Print Superconducting Topological Insulators Print Three-dimensional topological insulators (TIs), discovered experimentally in 2007-2009 by a Princeton-ALS collaboration, are a promising platform for developing the next generation of electronics. Electrons within one nanometer of a TI's surface move at high speeds in a "light-like" fashion. The quantum interactions that generate these electronic states cause individual electrons to be spin polarized even at room temperature and to strongly resist scattering from defects, naturally achieving some of the most desirable traits for computing components and next-generation "spintronics" technologies. More recent angle-resolved photoemission spectroscopy (ARPES) studies performed at ALS Beamlines 10.0.1 and 12.0.1 by the same collaboration have paved a way for these novel material properties to be taken even further. Their studies showed that by doping the TI, bismuth selenide, with copper, it's possible to make the topologically ordered electrons superconducting, dropping electrical resistance in the surface states all the way to zero.

163

Surprising Quasiparticle Interactions in Graphene  

NLE Websites -- All DOE Office Websites (Extended Search)

Surprising Quasiparticle Interactions in Graphene Print Surprising Quasiparticle Interactions in Graphene Print Until now, the world's electronics have been dominated by silicon, whose properties, while excellent, significantly limit the size and power consumption of today's computer chips. In order to develop ever smaller and more efficient devices, scientists have turned their attention to carbon, which can be formed into nanostructures like nanotubes, whose properties can be tuned from metallic to semiconducting. However, using carbon nanotubes for complex circuits is nearly impossible because their location and functionality in devices cannot be controlled at will, making them a poor substitute for silicon. Graphene, however, does not have these limitations. This single sheet of carbon atoms that is the building block of carbon nanotubes, C60 molecules, and graphite turns out to have similar functionality but with the added benefit that it can be grown with conventional methods and patterned into devices. Now, a group of scientists from Germany and the ALS, using angle-resolved photoemission spectroscopy (ARPES) at ALS Beamine 7.0.1, have succeeded in making the first measurement of the carrier lifetime in graphene over a wide energy scale and have found surprising new interactions that suggest new kinds of devices.

164

First Direct Evidence of Dirac Fermions in Graphite  

NLE Websites -- All DOE Office Websites (Extended Search)

Direct Evidence of Dirac Fermions in Graphite Print Direct Evidence of Dirac Fermions in Graphite Print The recent surge of interest in the electronic properties of graphene-that is, isolated layers of graphite just one atomic layer thick-has largely been driven by the discovery that electron mobility in graphene is ten times higher than in commercial-grade silicon, raising the possibility of high-efficiency, low-power, carbon-based electronics. Scientists attribute graphene's surprising current capacity (as well as a number of even stranger phenomena) to the presence of charge carriers that behave as if they are massless, "relativistic" quasiparticles called Dirac fermions. Harnessing these quasiparticles in real-world carbon-based devices, however, requires a deeper knowledge of their behavior under less-than-ideal circumstances, such as around defects, at edges, or in three dimensions-in other words, in graphite. At the ALS, a team of researchers using angle-resolved photoemission spectroscopy (ARPES) have now produced the first direct evidence of massless Dirac fermions in graphite coexisting with quasiparticles of finite effective mass and defect-induced localized states.

165

First Direct Evidence of Dirac Fermions in Graphite  

NLE Websites -- All DOE Office Websites (Extended Search)

Direct Evidence of Dirac Fermions in Graphite Print Direct Evidence of Dirac Fermions in Graphite Print The recent surge of interest in the electronic properties of graphene-that is, isolated layers of graphite just one atomic layer thick-has largely been driven by the discovery that electron mobility in graphene is ten times higher than in commercial-grade silicon, raising the possibility of high-efficiency, low-power, carbon-based electronics. Scientists attribute graphene's surprising current capacity (as well as a number of even stranger phenomena) to the presence of charge carriers that behave as if they are massless, "relativistic" quasiparticles called Dirac fermions. Harnessing these quasiparticles in real-world carbon-based devices, however, requires a deeper knowledge of their behavior under less-than-ideal circumstances, such as around defects, at edges, or in three dimensions-in other words, in graphite. At the ALS, a team of researchers using angle-resolved photoemission spectroscopy (ARPES) have now produced the first direct evidence of massless Dirac fermions in graphite coexisting with quasiparticles of finite effective mass and defect-induced localized states.

166

Nature and Origin of the Cuprate Pseudogap  

NLE Websites -- All DOE Office Websites (Extended Search)

Nature and Origin of the Cuprate Pseudogap Print Nature and Origin of the Cuprate Pseudogap Print The workings of high-temperature superconductive (HTSC) materials are a mystery wrapped in an enigma. However, a team of researchers from the ALS, Brookhaven National Laboratory, and Cornell University has taken a major step in understanding part of this mystery-the nature and origin of the pseudogap. Using angle-resolved photoemission spectroscopy (ARPES) and scanning tunneling microscopy (STM), they have determined the electronic structure of La2-xBaxCuO4 (LBCO), a unique system in which superconductivity is strongly suppressed and static spin and charge orders develop near a doping level of x = 1/8. Getting Wired with HTSCs Ever since the discovery of high-temperature superconductors (HTSCs), researchers have wrestled with not only theory, but application. One of the main problems is critical temperature, the temperature below which electrons can move within a material without resistance. The first HTSCs conducted electricity at 35 kelvin (K). Researchers keep pushing this limit, and today HTSCs can superconduct at 138 K. However, until a material is found that superconducts above 300 K, a cooling system is required.

167

Superconducting Topological Insulators  

NLE Websites -- All DOE Office Websites (Extended Search)

Superconducting Topological Insulators Print Superconducting Topological Insulators Print Three-dimensional topological insulators (TIs), discovered experimentally in 2007-2009 by a Princeton-ALS collaboration, are a promising platform for developing the next generation of electronics. Electrons within one nanometer of a TI's surface move at high speeds in a "light-like" fashion. The quantum interactions that generate these electronic states cause individual electrons to be spin polarized even at room temperature and to strongly resist scattering from defects, naturally achieving some of the most desirable traits for computing components and next-generation "spintronics" technologies. More recent angle-resolved photoemission spectroscopy (ARPES) studies performed at ALS Beamlines 10.0.1 and 12.0.1 by the same collaboration have paved a way for these novel material properties to be taken even further. Their studies showed that by doping the TI, bismuth selenide, with copper, it's possible to make the topologically ordered electrons superconducting, dropping electrical resistance in the surface states all the way to zero.

168

Surprising Quasiparticle Interactions in Graphene  

NLE Websites -- All DOE Office Websites (Extended Search)

Surprising Quasiparticle Surprising Quasiparticle Interactions in Graphene Surprising Quasiparticle Interactions in Graphene Print Wednesday, 31 October 2007 00:00 Until now, the world's electronics have been dominated by silicon, whose properties, while excellent, significantly limit the size and power consumption of today's computer chips. In order to develop ever smaller and more efficient devices, scientists have turned their attention to carbon, which can be formed into nanostructures like nanotubes, whose properties can be tuned from metallic to semiconducting. However, using carbon nanotubes for complex circuits is nearly impossible because their location and functionality in devices cannot be controlled at will, making them a poor substitute for silicon. Graphene, however, does not have these limitations. This single sheet of carbon atoms that is the building block of carbon nanotubes, C60 molecules, and graphite turns out to have similar functionality but with the added benefit that it can be grown with conventional methods and patterned into devices. Now, a group of scientists from Germany and the ALS, using angle-resolved photoemission spectroscopy (ARPES) at ALS Beamine 7.0.1, have succeeded in making the first measurement of the carrier lifetime in graphene over a wide energy scale and have found surprising new interactions that suggest new kinds of devices.

169

Controlling Graphene's Electronic Structure  

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Controlling Graphene's Electronic Structure Print Controlling Graphene's Electronic Structure Print Graphene, because of its unusual electron properties, reduced dimensionality, and scale, has enormous potential for use in ultrafast electronic transistors. It exhibits high conductivity and an anomalous quantum Hall effect (a phenomenon exhibited by certain semiconductor devices at low temperatures and high magnetic fields). Among its novel properties, graphene's electrical charge carriers (electrons and holes) move through a solid with effectively zero mass and constant velocity, like photons. Graphene's intrinsically low scattering rate from defects implies the possibility of a new kind of electronics based on the manipulation of electrons as waves rather than particles. The primary technical difficulty has been controlling the transport of electrical charge carriers through the sheet. This area of research is known as bandgap engineering. While bandgap engineering is the basis of semiconductor technology, it is only now being applied to graphene. Using angle-resolved photoemission spectroscopy (ARPES) at ALS Beamline 7.0.1, a team of scientists from the ALS and Germany characterized the electronic band structure and successfully controlled the gap between valence and conduction bands in a bilayer of graphene thin films deposited on a substrate of silicon carbide. This was done by doping one sheet with adsorbed potassium atoms, creating an asymmetry between the two layers.

170

Nature and Origin of the Cuprate Pseudogap  

NLE Websites -- All DOE Office Websites (Extended Search)

Nature and Origin of the Cuprate Pseudogap Print Nature and Origin of the Cuprate Pseudogap Print The workings of high-temperature superconductive (HTSC) materials are a mystery wrapped in an enigma. However, a team of researchers from the ALS, Brookhaven National Laboratory, and Cornell University has taken a major step in understanding part of this mystery-the nature and origin of the pseudogap. Using angle-resolved photoemission spectroscopy (ARPES) and scanning tunneling microscopy (STM), they have determined the electronic structure of La2-xBaxCuO4 (LBCO), a unique system in which superconductivity is strongly suppressed and static spin and charge orders develop near a doping level of x = 1/8. Getting Wired with HTSCs Ever since the discovery of high-temperature superconductors (HTSCs), researchers have wrestled with not only theory, but application. One of the main problems is critical temperature, the temperature below which electrons can move within a material without resistance. The first HTSCs conducted electricity at 35 kelvin (K). Researchers keep pushing this limit, and today HTSCs can superconduct at 138 K. However, until a material is found that superconducts above 300 K, a cooling system is required.

171

Nature and Origin of the Cuprate Pseudogap  

NLE Websites -- All DOE Office Websites (Extended Search)

Nature and Origin of the Cuprate Pseudogap Print Nature and Origin of the Cuprate Pseudogap Print The workings of high-temperature superconductive (HTSC) materials are a mystery wrapped in an enigma. However, a team of researchers from the ALS, Brookhaven National Laboratory, and Cornell University has taken a major step in understanding part of this mystery-the nature and origin of the pseudogap. Using angle-resolved photoemission spectroscopy (ARPES) and scanning tunneling microscopy (STM), they have determined the electronic structure of La2-xBaxCuO4 (LBCO), a unique system in which superconductivity is strongly suppressed and static spin and charge orders develop near a doping level of x = 1/8. Getting Wired with HTSCs Ever since the discovery of high-temperature superconductors (HTSCs), researchers have wrestled with not only theory, but application. One of the main problems is critical temperature, the temperature below which electrons can move within a material without resistance. The first HTSCs conducted electricity at 35 kelvin (K). Researchers keep pushing this limit, and today HTSCs can superconduct at 138 K. However, until a material is found that superconducts above 300 K, a cooling system is required.

172

BEAMLINE 5-4  

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5-4 5-4 CURRENT STATUS: Open SUPPORTED TECHNIQUES: Very High Energy Resolution; Photoemission Angle-Resolved Photoelectron Spectroscopy MAIN SCIENTIFIC DISCIPLINES: Materials % TIME GENERAL USE: 100% SCHEDULING: Proposal Submittal and Scheduling Procedures Current SPEAR and Beam Line Schedules SOURCE: 10-period undulator, maximum field 0.61 T BEAM LINE SPECIFICATIONS: energy range grating type resolution DE/E spot size flux angular acceptance focused 7-40 eV 1700 l/mm: 7-18 eV, E/DE > 10000 2800 l/mm: 16-32 eV, E/DE> 10000 3600 l/mm: 20-40 eV, E/DE> 10000 ≥1 x 10-4 0.5 x 0.6 mm2 ~1011 >1.5 mrad OPTICS: M0: horizontal deflecting, flat, water-cooled M1: vertical focusing 10:1, elliptically cylinder M3: horizontal refocusing 1:1, cylinder M4: vertical refocusing 1:1, cylinder

173

Superconducting Topological Insulators  

NLE Websites -- All DOE Office Websites (Extended Search)

Superconducting Topological Insulators Print Superconducting Topological Insulators Print Three-dimensional topological insulators (TIs), discovered experimentally in 2007-2009 by a Princeton-ALS collaboration, are a promising platform for developing the next generation of electronics. Electrons within one nanometer of a TI's surface move at high speeds in a "light-like" fashion. The quantum interactions that generate these electronic states cause individual electrons to be spin polarized even at room temperature and to strongly resist scattering from defects, naturally achieving some of the most desirable traits for computing components and next-generation "spintronics" technologies. More recent angle-resolved photoemission spectroscopy (ARPES) studies performed at ALS Beamlines 10.0.1 and 12.0.1 by the same collaboration have paved a way for these novel material properties to be taken even further. Their studies showed that by doping the TI, bismuth selenide, with copper, it's possible to make the topologically ordered electrons superconducting, dropping electrical resistance in the surface states all the way to zero.

174

Electron-State Hybridization in Heavy-Fermion Systems  

NLE Websites -- All DOE Office Websites (Extended Search)

Electron-State Hybridization in Heavy-Fermion Systems Print Electron-State Hybridization in Heavy-Fermion Systems Print Heavy-fermion systems are characterized by electrons with extremely large effective masses. The corresponding heavy-electron "quasiparticle" states are close to the Fermi energy and govern the thermodynamic, transport, and, in part, magnetic properties of these materials. In the case of rare-earth compounds, the quasiparticle states arise from the interactions (hybridization) of valence states with strongly localized 4f states. The question as to whether it is sufficient to treat the f states as localized impurities (single-impurity Anderson model) or whether the periodic crystal symmetry must be considered (periodic Anderson model) has been the subject of extensive debate. An international team of researchers from Germany, Ukraine, India, and the U.S. has performed angle-resolved photoemission spectroscopy (ARPES) studies of the heavy-fermion system YbIr2Si2. The results show a strong momentum (directional) dependence of the hybridization that clearly rules out the single-impurity model in favor of the lattice model.

175

ARPES Provides Direct Evidence of Spin-Wave Coupling  

NLE Websites -- All DOE Office Websites (Extended Search)

ARPES Provides Direct Evidence ARPES Provides Direct Evidence of Spin-Wave Coupling ARPES Provides Direct Evidence of Spin-Wave Coupling Print Wednesday, 30 March 2005 00:00 The electronic properties of a metal are determined by the dynamical behavior of its conduction electrons. Conventional band theory accounts for the interaction of the electrons with the static ion lattice. However, coupling to further microscopic degrees of freedom can alter the electron dynamics considerably. For example, "conventional" superconductivity emerges as a result of the electrons' interaction with lattice vibrations (phonons). In magnetic materials, coupling with spin waves (magnons) is also expected. Such interactions may contribute to high-temperature superconductivity in novel materials. Unfortunately, lattice vibrations and spin waves have similar energy scales, hindering detailed study. Researchers have taken a new approach in analyzing the electron bands of ferromagnetic iron. Angle-resolved photoemission spectroscopy (ARPES) provides direct spectroscopic evidence of altered electron mass and energy (quasiparticle formation) in a magnetic solid due to coupling with spin waves.

176

ARPES Studies of Cuprate Fermiology: Superconductivity, Pseudogap and Quasiparticle Dynamics  

Science Conference Proceedings (OSTI)

We present angle-resolved photoemission spectroscopy (ARPES) studies of the cuprate high-temperature superconductors which elucidate the relation between superconductivity and the pseudogap and highlight low-energy quasiparticle dynamics in the superconducting state. Our experiments suggest that the pseudogap and superconducting gap represent distinct states, which coexist below T{sub c}. Studies on Bi-2212 demonstrate that the near-nodal and near-antinodal regions behave differently as a function of temperature and doping, implying that different orders dominate in different momentum-space regions. However, the ubiquity of sharp quasiparticles all around the Fermi surface in Bi-2212 indicates that superconductivity extends into the momentum-space region dominated by the pseudogap, revealing subtlety in this dichotomy. In Bi-2201, the temperature dependence of antinodal spectra reveals particle-hole asymmetry and anomalous spectral broadening, which may constrain the explanation for the pseudogap. Recognizing that electron-boson coupling is an important aspect of cuprate physics, we close with a discussion of the multiple 'kinks' in the nodal dispersion. Understanding these may be important to establishing which excitations are important to superconductivity.

Vishik, Inna

2011-06-23T23:59:59.000Z

177

Evidence for a Lifshitz transition in electron-doped iron arsenic superconductors at the onset of superconductivity  

Science Conference Proceedings (OSTI)

The iron arsenic high-temperature superconductors exhibit particularly rich phase diagrams. In the AE(Fe{sub 1-x}T{sub x}){sub 2}As{sub 2} family (known as '122', with AE being Ca, Sr or Ba and T being a transition metal), the simultaneous structural/magnetic phase transition that occurs at elevated temperature in the undoped material splits and is suppressed by carrier doping. A superconducting region appears as likely in the orthorhombic/antiferromagnetic (AFM) state as in the tetragonal/paramagnetic state. An important question then is what determines the critical doping at which superconductivity emerges, as the AFM order is fully suppressed only close to optimal doping. Here we report evidence from angle-resolved photoemission spectroscopy that marked changes in the Fermi surface coincide with the onset of superconductivity in electron-doped Ba(Fe{sub 1-x}Co{sub x}){sub 2}As{sub 2}. The presence of the AFM order leads to a reconstruction of the electronic structure, most significantly the appearance of the petal-like hole pockets at the Fermi level. These hole pockets vanish - that is, undergo a Lifshitz transition - as the cobalt concentration is increased sufficiently to support superconductivity. Superconductivity and magnetism are competing states in this system: when petal-like hole pockets are present, superconductivity is fully suppressed, whereas in their absence the two states can coexist.

Liu, Chang; Kondo, T.; Fernandes, R.M.; Palczewski, Ari D.; Mun, Eun Deok; Ni, Ni; Thaler, Alexander N.; Bostwick, Aaron; Rotenberg, Eli; Schmalian, Jorg; Bud-ko, Sergey L.; Canfield, Paul C.; and Kaminski, A.

2010-05-02T23:59:59.000Z

178

Electronic Reconstruction through the Structural and Magnetic Transitions in Detwinned NaFeAs  

SciTech Connect

We use angle-resolved photoemission spectroscopy to study twinned and detwinned iron pnictide compound NaFeAs. Distinct signatures of electronic reconstruction are observed to occur at the structural (T{sub S}) and magnetic (T{sub SDW}) transitions. At T{sub S}, C{sub 4} rotational symmetry is broken in the form of an anisotropic shift of the orthogonal d{sub xz} and d{sub yz} bands. The magnitude of this orbital anisotropy rapidly develops to near completion upon approaching T{sub SDW}, at which temperature band folding occurs via the antiferromagnetic ordering wave vector. Interestingly, the anisotropic band shift onsetting at T{sub S} develops in such a way to enhance the nesting conditions in the C{sub 2} symmetric state, hence is intimately correlated with the long range collinear AFM order. Furthermore, the similar behaviors of the electronic reconstruction in NaFeAs and Ba(Fe{sub 1-x}Co{sub x}){sub 2}As{sub 2} suggests that this rapid development of large orbital anisotropy between T{sub S} and T{sub SDW} is likely a general feature of the electronic nematic phase in the iron pnictides, and the associated orbital fluctuations may play an important role in determining the ground state properties.

Yi, M.; Lu, D.H.; Moore, R.G.; Kihou, K; Lee, C-H; Iyo, A.; Eisaki, H.; Yoshida, T; Fujimori, A; Shen, Z-X

2012-05-25T23:59:59.000Z

179

Electronic structure of the iron-based superconductor LaOFeP  

Science Conference Proceedings (OSTI)

The recent discovery of superconductivity in the so-called iron-oxypnictide family of compounds has generated intense interest. The layered crystal structure with transition metal ions in planar square lattice form and the discovery of spin-density-wave order near 130K seem to hint at a strong similarity with the copper oxide superconductors. A burning current issue is the nature of the ground state of the parent compounds. Two distinct classes of theories have been put forward depending on the underlying band structures: local moment antiferromagnetic ground state for strong coupling approach and itinerant ground state for weak coupling approach. The local moment magnetism approach stresses on-site correlations and proximity to a Mott insulating state and thus the resemblance to cuprates; while the latter approach emphasizes the itinerant electron physics and the interplay between the competing ferromagnetic and antiferromagnetic fluctuations. Such a controversy is partly due to the lack of conclusive experimental information on the electronic structures. Here we report the first angle-resolved photoemission spectroscopy (ARPES) investigation of LaOFeP (T{sub c} = 5.9 K), the first reported iron-based superconductor. Our results favor the itinerant ground state, albeit with band renormalization. In addition, our data reveal important differences between these and copper based superconductors.

Lu, D.H.; Yi, M.; /Stanford U., Phys. Dept. /SLAC, SSRL; Mo1, S.-K.; /Stanford U., Phys. Dept. /SLAC, SSRL /LBNL, ALS; Erickson, A.S.; Analytis, J.; Chu, J.-H.; /Stanford U., Geballe Lab.; Singh, D.J.; /Oak Ridge; Hussain, Z.; /LBNL, ALS; Geballe, T.H.; Fisher, I.R.; /Stanford U., Geballe Lab.; Shen, Z.-X.; /Stanford U., Phys. Dept. /SLAC, SSRL

2010-02-15T23:59:59.000Z

180

Particle-Hole Symmetry Breaking in the Pseudogap State of Bi2201  

Science Conference Proceedings (OSTI)

In conventional superconductors, a gap exists in the energy absorption spectrum only below the transition temperature (T{sub c}), corresponding to the energy price to pay for breaking a Cooper pair of electrons. In high-T{sub c} cuprate superconductors above T{sub c}, an energy gap called the pseudogap exists, and is controversially attributed either to pre-formed superconducting pairs, which would exhibit particle-hole symmetry, or to competing phases which would typically break it. Scanning tunnelling microscopy (STM) studies suggest that the pseudogap stems from lattice translational symmetry breaking and is associated with a different characteristic spectrum for adding or removing electrons (particle-hole asymmetry). However, no signature of either spatial or energy symmetry breaking of the pseudogap has previously been observed by angle-resolved photoemission spectroscopy (ARPES). Here we report ARPES data from Bi2201 which reveals both particle-hole symmetry breaking and dramatic spectral broadening indicative of spatial symmetry breaking without long range order, upon crossing through T* into the pseudogap state. This symmetry breaking is found in the dominant region of the momentum space for the pseudogap, around the so-called anti-node near the Brillouin zone boundary. Our finding supports the STM conclusion that the pseudogap state is a broken-symmetry state that is distinct from homogeneous superconductivity.

Hashimoto, M.; /SIMES, Stanford /Stanford U., Geballe Lab. /LBNL, ALS; He, R.-H.; /aff SIMES, Stanford /Stanford U., Geballe Lab.; Tanaka, K.; /aff SIMES, Stanford /Stanford U., Geballe Lab. /LBNL, ALS /Osaka U.; Testaud, J.P.; /SIMES, Stanford /Stanford U., Geballe Lab. /LBNL, ALS; Meevasana1, W.; Moore, R.G.; Lu, D.H.; /SIMES, Stanford /Stanford U., Geballe Lab.; Yao, H.; /SIMES, Stanford; Yoshida, Y.; Eisaki, H.; /AIST, Tsukuba; Devereaux, T.P.; /SIMES, Stanford /Stanford U., Geballe Lab.; Hussain, Z.; /LBNL, ALS; Shen, Z.-X.; /SIMES, Stanford /Stanford U., Geballe Lab.

2011-08-19T23:59:59.000Z

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181

Surface damages in diamond by Ar/O{sub 2} plasma and their effect on the electrical and electrochemical characteristics of boron-doped layers  

Science Conference Proceedings (OSTI)

Epitaxial single crystal and boron-doped diamond layers were exposed to reactive ion etching in Ar/O{sub 2} plasma (rf power of 25 W and self-bias of 100 V); and the electrical, structural, and electrochemical characteristics of the exposed surface were investigated. Angle-resolved x-ray photoemission spectroscopy (XPS) measurements revealed a nonuniform layer of amorphous carbon at the exposed surface with an average thickness of approximately 4 nm, as confirmed also by atomic force microscopy profiling of selectively etched areas. On highly boron-doped diamond, the plasma-induced damages resulted also in a nonconductive surface layer. This damaged and insulating surface layer remained resistant to graphite-etching chemicals and to rf oxygen plasma but it was removed completely in microwave hydrogen plasma at 700 deg. C. The surface characteristics after the H-plasma process followed by wet chemical oxidation were restored back to the initial state, as confirmed by XPS. Such ''recovery'' treatment had been applied to an all-diamond submicrometer electrode array initially patterned by an Ar/O{sub 2} plasma etching. The electrochemical characteristics of this electrode array were improved by more than two orders of magnitude, approaching theoretical limit for the given geometrical configuration.

Denisenko, A.; Pietzka, C.; Scharpf, J.; Kohn, E. [Institute of Electron Devices and Circuits, University of Ulm, 89069 Ulm (Germany); Romanyuk, A. [Institute of Physics, University of Basel, 4056 Basel (Switzerland)

2010-10-15T23:59:59.000Z

182

Tuning of the Metal-Insulator Transition via Alkali Adsorption  

NLE Websites -- All DOE Office Websites (Extended Search)

Tuning of the Metal-Insulator Tuning of the Metal-Insulator Transition via Alkali Adsorption Tuning of the Metal-Insulator Transition via Alkali Adsorption Print Wednesday, 29 March 2006 00:00 Turning a material from an insulator to a metal, or vice versa, by light irradiation, exposure to electric or magnetic fields, or applying small changes in temperature, pressure, or doping-such intriguing control of a material's electronic properties is possible by exploiting strongly interacting or "correlated" electrons. Now a team of researchers from the University of Kiel in Germany and the ALS has found a novel, surprising way to continuously transform a layered metallic transition-metal compound, TaS2, into an insulator. Using angle-resolved photoemission spectroscopy (ARPES), they have demonstrated that adsorption of alkali atoms onto this material's surface gradually makes it more insulating, although in general, alkali adsorption should lead to more metallic behavior, as alkali atoms easily give away their loosely bound outermost electron.

183

Electron-State Hybridization in Heavy-Fermion Systems  

NLE Websites -- All DOE Office Websites (Extended Search)

Electron-State Hybridization in Heavy-Fermion Systems Print Electron-State Hybridization in Heavy-Fermion Systems Print Heavy-fermion systems are characterized by electrons with extremely large effective masses. The corresponding heavy-electron "quasiparticle" states are close to the Fermi energy and govern the thermodynamic, transport, and, in part, magnetic properties of these materials. In the case of rare-earth compounds, the quasiparticle states arise from the interactions (hybridization) of valence states with strongly localized 4f states. The question as to whether it is sufficient to treat the f states as localized impurities (single-impurity Anderson model) or whether the periodic crystal symmetry must be considered (periodic Anderson model) has been the subject of extensive debate. An international team of researchers from Germany, Ukraine, India, and the U.S. has performed angle-resolved photoemission spectroscopy (ARPES) studies of the heavy-fermion system YbIr2Si2. The results show a strong momentum (directional) dependence of the hybridization that clearly rules out the single-impurity model in favor of the lattice model.

184

High-resolution core-level photoemission study of CF{sub 4}-treated Gd{sub 2}O{sub 3}(Ga{sub 2}O{sub 3}) gate dielectric on Ge probed by synchrotron radiation  

SciTech Connect

High-resolution core-level photoemission analysis using synchrotron radiation was used to investigate the superior electrical performance of aGa{sub 2}O{sub 3}(Gd{sub 2}O{sub 3}) gate dielectric on Ge(001) after CF{sub 4} treatment. Prior to the treatment, a thin germanate-like oxide layer that formed at the interface prevented Ge from diffusing to the surface. The Ge surface retained a small amount of buckled dimers from the as-grown sample. The buckled dimers were quickly removed by CF{sub 4} plasma treatment followed by an annealing process, resulting in a more uniform interface than that of the as-grown sample. The detailed interfacial electronic structure for the untreated and treated samples are presented.

Pi, T.-W. [National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan (China); Huang, M. L.; Kwo, J. [Center for Condensed Matter Sciences, National Taiwan University, Taipei 10617, Taiwan (China); Department of Physics, National TsingHua University, Hsinchu 30013, Taiwan (China); Lee, W. C.; Chu, L. K.; Lin, T. D.; Chiang, T. H.; Wang, Y. C.; Wu, Y. D.; Hong, M. [Department of Materials Science and Engineering, National TsingHua University, Hsinchu 30013, Taiwan (China)

2011-02-07T23:59:59.000Z

185

The COMPASS Hadron Spectroscopy Programme  

E-Print Network (OSTI)

COMPASS is a fixed-target experiment at the CERN SPS for the investigation of the structure and the dynamics of hadrons. The experimental setup features a large acceptance and high momentum resolution spectrometer including particle identification and calorimetry and is therefore ideal to access a broad range of different final states. Following the promising observation of a spin-exotic resonance during an earlier pilot run, COMPASS focused on light-quark hadron spectroscopy during the years 2008 and 2009. A data set, world leading in terms of statistics and resolution, has been collected with a 190GeV/c hadron beam impinging on either liquid hydrogen or nuclear targets. Spin-exotic meson and glueball candidates formed in both diffractive dissociation and central production are presently studied. Since the beam composition includes protons, the excited baryon spectrum is also accessible. Furthermore, Primakoff reactions have the potential to determine radiative widths of the resonances and to probe chiral pe...

Austregesilo, A

2012-01-01T23:59:59.000Z

186

Photoelectron spectroscopy of negative ions  

Science Conference Proceedings (OSTI)

Ultraviolet photoelectron spectroscopy of negative ions was used to probe the anionic and neutral states of the halogen monoxides, halogen dioxides, halocarbenes, and fluorovinylidene species. Ions, created in a flowing afterglow source, were mass selected and photodetached by continuous monochromatic laser radiation, and the kinetic energy of the photodetached electrons were determined. The photoelectron spectra provide electronic and vibrational structure. Photoelectron spectra of the halogen monoxides yielded adiabatic electron affinities, neutral and anion frequencies, and spin-orbit splittings. Franck-Condon analyses provided the change in bond length between the neutral and anion species. Neutral heats of formation and dissociation energies were combined with electron affinities to determine anion heats of formation and dissociation energies. Adiabatic electron affinities, neutral vibrational frequencies and anion vibrational frequencies were determined from photoelectron spectra of OClO[sup [minus

Gilles, M.K.

1993-01-01T23:59:59.000Z

187

Spectroscopy of {sup 257}Rf.  

Science Conference Proceedings (OSTI)

The isotope {sup 257}Rf was produced in the fusion-evaporation reaction {sup 208}Pb({sup 50}Ti,n){sup 257}Rf. Reaction products were separated and identified by mass. Delayed spectroscopy of {sup 257}Rf and its decay products was performed. A partial decay scheme with configuration assignments is proposed based on hindrance factors. The excitation energy of the 1/2{sup +}[620] configuration in {sup 253}No is proposed. The energy of this 1/2{sup +} state in a series of N=151 isotones increases with nuclear charge, reflecting an increase in the N=152 gap. This gap is deduced to grow substantially from 850 to 1400 keV between Z=94 and 102. An isomeric state in {sup 257}Rf, with a half-life of 160{sub -31}{sup +42} {micro}s, was discovered by detecting internal conversion electrons followed by decay. It is interpreted as a three-quasiparticle high-K isomer. A second group of internal conversion electrons, with a half-life of 4.1{sub -1.3}{sup +2.4} s, followed by decay, was also observed. These events might originate from the decay of excited states in {sup 257}Lr, populated by electron-capture decay of {sup 257}Rf. Fission of {sup 257}Rf was unambiguously detected, with a branching ratio of b{sub Rf}{sup SF} = 0.02 {+-} 0.01.

Qian, J.; Heinz, A.; Khoo, T. L.; Janssens, R. V. F.; Peterson, D.; Seweryniak, D.; Ahmad, I.; Asai, M.; Back, B. B.; Carpenter, M. P.; Garnsworthy, A. B.; Greene, J. P.; Hecht, A. A.; Jiang, C. L.; Kondev, F. G.; Lauritsen, T.; Lister, C. J.; Robinson, A.; Savard, G.; Scott, R.; Vondrasek, R.; Wang, X.; Winkler, R.; Zhu, S.; Yale Univ.; Japan Atomic Energy Agency; Univ. of Surrey; Univ. of Maryland

2009-06-01T23:59:59.000Z

188

Spectroscopy of {sup 257}Rf  

Science Conference Proceedings (OSTI)

The isotope {sup 257}Rf was produced in the fusion-evaporation reaction {sup 208}Pb({sup 50}Ti,n){sup 257}Rf. Reaction products were separated and identified by mass. Delayed spectroscopy of {sup 257}Rf and its decay products was performed. A partial decay scheme with configuration assignments is proposed based on {alpha} hindrance factors. The excitation energy of the 1/2{sup +}[620] configuration in {sup 253}No is proposed. The energy of this 1/2{sup +} state in a series of N=151 isotones increases with nuclear charge, reflecting an increase in the N=152 gap. This gap is deduced to grow substantially from 850 to 1400 keV between Z=94 and 102. An isomeric state in {sup 257}Rf, with a half-life of 160{sub -31}{sup +42} {mu}s, was discovered by detecting internal conversion electrons followed by {alpha} decay. It is interpreted as a three-quasiparticle high-K isomer. A second group of internal conversion electrons, with a half-life of 4.1{sub -1.3}{sup +2.4} s, followed by {alpha} decay, was also observed. These events might originate from the decay of excited states in {sup 257}Lr, populated by electron-capture decay of {sup 257}Rf. Fission of {sup 257}Rf was unambiguously detected, with a branching ratio of b{sub Rf}{sup SF}=0.02{+-}0.01.

Qian, J.; Heinz, A.; Winkler, R. [WNSL, Yale University, New Haven, Connecticut 06511 (United States); Khoo, T. L.; Janssens, R. V. F.; Peterson, D.; Seweryniak, D.; Ahmad, I.; Back, B. B.; Carpenter, M. P.; Greene, J. P.; Jiang, C. L.; Kondev, F. G.; Lauritsen, T.; Lister, C. J.; Robinson, A.; Savard, G.; Scott, R.; Vondrasek, R.; Wang, X. [Argonne National Laboratory, Illinois 60439 (United States)] (and others)

2009-06-15T23:59:59.000Z

189

Method and apparatus for optoacoustic spectroscopy  

DOE Patents (OSTI)

A method and apparatus that significantly increases the sensitivity and flexibility of laser optoacoustic spectroscopy, with reduced size. With the method, it no longer is necessary to limit the use of laser optoacoustic spectroscopy to species whose absorption must match available laser radiation. Instead, "doping" with a relatively small amount of an optically absorbing gas yields optoacoustic signatures of nonabsorbing materials (gases, liquids, solids, and aerosols), thus significantly increasing the sensitivity and flexibility of optoacoustic spectroscopy. Several applications of this method are demonstated and/or suggested.

Amer, Nabil M. (Berkeley, CA)

1979-01-01T23:59:59.000Z

190

Instrument Series: Spectroscopy and Diffraction XPS Imaging  

NLE Websites -- All DOE Office Websites (Extended Search)

XPS Imaging XPS Imaging The X-ray photoelectron spectroscopy (XPS) imaging system provides fast, quantitative, real-time parallel imaging with highest resolution spectroscopy at all analysis areas. In addition, the system is equipped with temperature programmed desorption (TPD), ultraviolet photoelectron spectroscopy (UPS), ion scattering spectroscopy (ISS), a cluster/Ar + ion gun, and a five-axis automated stage with variable temperature sample environment at the analysis chamber. The system is also integrated with a radial distribution chamber (RDC), a full-size glove box, and a cold-stage at the sample introduction for air-sensitive, liquid-semisolid, biological and environmental sample transfers. In addition, the RDC has a simple sample transfer mechanism to the

191

An Evolutionary Approach in Quantitative Spectroscopy  

Science Conference Proceedings (OSTI)

This paper describes investigations into using evolutionary search for quantitative spectroscopy. Given the spectrum (intensity × frequency) of a sample of material of interest, we would like to be able to infer the make-up of the material in terms ...

Phil Husbands; Pedro Paulo Balbi de Oliveira

1998-11-01T23:59:59.000Z

192

Meson Spectroscopy at CLAS and CLAS12  

Science Conference Proceedings (OSTI)

We report on meson spectroscopy using the CLAS at Jefferson Lab. We study photo?production of exotic mesons and strangeonia on the largest data sample ever to be produced at photon energies of about 5 GeV. We also describe an experiment to continue meson spectroscopy at CLAS12 (CLAS energy upgrade) using electroproduction at very low Q 2 (“quasireal photons”) up to photon energies of 10 GeV.

Carlos Salgado; The CLAS Collaboration

2011-01-01T23:59:59.000Z

193

Spectroscopy and atomic force microscopy of biomass  

NLE Websites -- All DOE Office Websites (Extended Search)

Spectroscopy Spectroscopy and atomic force microscopy of biomass L. Tetard a,b , A. Passian a,b,n , R.H. Farahi a , U.C. Kalluri c , B.H. Davison c , T. Thundat a,b a Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA b Department of Physics, University of Tennessee, Knoxville, TN 37996, USA c Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA a r t i c l e i n f o Keywords: Atomic force microscopy Spectroscopy Plant cells Biomass Nanomechanics a b s t r a c t Scanning probe microscopy has emerged as a powerful approach to a broader understanding of the molecular architecture of cell walls, which may shed light on the challenge of efficient cellulosic ethanol production. We have obtained preliminary images of both Populus and switchgrass samples using atomic force microscopy (AFM). The results show distinctive features that are shared by switchgrass

194

Ultrafast Spectroscopy of Warm Dense Matter  

NLE Websites -- All DOE Office Websites (Extended Search)

Ultrafast Spectroscopy of Warm Dense Matter Print Ultrafast Spectroscopy of Warm Dense Matter Print Being neither solid, liquid, gas, nor plasma, warm dense matter (WDM) occupies a no man's land in the map of material phases. Its temperature can range between that of planetary cores (tens of thousands K) to that of stellar cores (hundreds of thousands K). Not only is it prevalent throughout the universe, it is relevant to inertial confinement fusion (ICF) and material performance under extreme conditions. However, because of its extreme temperatures and pressures, WDM tends to be drastically transient and thus difficult to study in the laboratory. Now, researchers have set up ultrafast x-ray absorption spectroscopy at the ALS to measure the electronic structure of WDMs, demonstrating that fast-changing electron temperatures of matter under extreme conditions can be determined with picosecond resolution.

195

Synchrotron Mossbauer Spectroscopy of powder samples  

SciTech Connect

Synchrotron Mossbauer Spectroscopy, SMS, is an emerging technique that allows fast and accurate determination of hyperfine field parameters similar to conventional Mossbauer spectroscopy with radioactive sources. This new technique, however, is qualitatively different from Mossbauer spectroscopy in terms of equipment, methodology, and analysis to warrant a new name. In this paper, the authors report on isomer shift and quadrupole splitting measurements of Mohr`s salt, Fe(NH{sub 4}){sub 2}(SO{sub 4}){sub 2}{center_dot}6H{sub 2}O for demonstration purposes. Theoretical calculations were performed and compared to experiments both in energy and time domain to demonstrate the influence of thickness distribution and preferential alignment of powder samples. Such measurements may prove to be useful when the data collection times are reduced to few seconds in the third generation, undulator based synchrotron radiation sources.

Alp, E.E.; Sturhahn, W.; Toellner, T.

1994-08-01T23:59:59.000Z

196

Compressed sensing for multidimensional electronic spectroscopy experiments  

E-Print Network (OSTI)

Compressed sensing is a processing method that significantly reduces the number of measurements needed to accurately resolve signals in many fields of science and engineering. We develop a two-dimensional (2D) variant of compressed sensing for multidimensional electronic spectroscopy and apply it to experimental data. For the model system of atomic rubidium vapor, we find that compressed sensing provides significantly better resolution of 2D spectra than a conventional discrete Fourier transform from the same experimental data. We believe that by combining powerful resolution with ease of use, compressed sensing can be a powerful tool for the analysis and interpretation of ultrafast spectroscopy data.

J. N. Sanders; S. Mostame; S. K. Saikin; X. Andrade; J. R. Widom; A. H. Marcus; A. Aspuru-Guzik

2012-07-16T23:59:59.000Z

197

Spectroscopy of element 115 decay chains  

Science Conference Proceedings (OSTI)

A high-resolution a, X-ray and -ray coincidence spectroscopy experiment was conducted at the GSI Helmholtzzentrum fu r Schwerionenforschung. Thirty correlated a-decay chains were detected following the fusion-evaporation reaction 48Ca + 243Am. The observations are consistent with previous assignments of similar decay chains to originate from element Z = 115. The data includes first candidates of fingerprinting the decay step Mt --> Bh with characteristic X rays. For the first time, precise spectroscopy allows the derivation of excitation schemes of isotopes along the decay chains starting with elements Z > 112. Comprehensive Monte-Carlo simulations accompany the data analysis. Nuclear structure models provide a first level interpretation.

Rudolph, Dirk [Lund University, Sweden; Forsberg, U. [Lund University, Sweden; Golubev, P. [Lund University, Sweden; Sarmiento, L. G. [Lund University, Sweden; Yakushev, A. [Gesellschaft fur Schwerionenforschung (GSI), Germany; Andersson, L.-L. [Johannes Gutenberg-Universitaet Mainz, Mainz, Germany; Di Nitto, A. [Johannes Gutenberg-Universitaet Mainz, Mainz, Germany; Duehllmann, Ch. E. [Gesellschaft fur Schwerionenforschung (GSI), Germany; Gates, J. M. [Lawrence Berkeley National Laboratory (LBNL); Gregorich, K. E. [Lawrence Berkeley National Laboratory (LBNL); Gross, Carl J [ORNL; Hessberger, F. P. [Gesellschaft fur Schwerionenforschung (GSI), Germany; Herzberg, R.-D [University of Liverpool; Khuyagbaatar, J. [Johannes Gutenberg-Universitaet Mainz, Mainz, Germany; Kratz, J. V. [Johannes Gutenberg-Universitaet Mainz, Mainz, Germany; Rykaczewski, Krzysztof Piotr [ORNL; Schaedel, M. [Gesellschaft fur Schwerionenforschung (GSI), Germany; Aberg, S. [Lund University, Sweden; Ackermann, D. [GSI-Hemholtzzentrum fur Schwerionenforschung, Darmstadt, Germany; Block, M. [Gesellschaft fur Schwerionenforschung (GSI), Germany; Brand, H. [Gesellschaft fur Schwerionenforschung (GSI), Germany; Carlsson, B. G. [Lund University, Sweden; Cox, D. [University of Liverpool; Derkx, X. [Johannes Gutenberg-Universitaet Mainz, Mainz, Germany; Eberhardt, K. [Johannes Gutenberg-Universitaet Mainz, Mainz, Germany; Even, J. [Johannes Gutenberg-Universitaet Mainz, Mainz, Germany; Fahlander, C. [Lund University, Sweden; Gerl, J. [Gesellschaft fur Schwerionenforschung (GSI), Germany; Jaeger, E. [Gesellschaft fur Schwerionenforschung (GSI), Germany; Kindler, B. [Gesellschaft fur Schwerionenforschung (GSI), Germany; Krier, J. [Gesellschaft fur Schwerionenforschung (GSI), Germany; Kojouharov, I. [Gesellschaft fur Schwerionenforschung (GSI), Germany; Kurz, N. [Gesellschaft fur Schwerionenforschung (GSI), Germany; Lommel, B. [Gesellschaft fur Schwerionenforschung (GSI), Germany; Mistry, A. [University of Liverpool; Mokry, C. [Johannes Gutenberg-Universitaet Mainz, Mainz, Germany; Nitsche, H. [Lawrence Berkeley National Laboratory (LBNL); Omtvedt, J. P. [Paul Scherrer Institut, Villigen, Switzerland; Papadakis, P. [University of Liverpool; Ragnarsson, I. [Lund University, Sweden; Runke, J. [Gesellschaft fur Schwerionenforschung (GSI), Germany; Schaffner, H. [Gesellschaft fur Schwerionenforschung (GSI), Germany; Schausten, B. [Gesellschaft fur Schwerionenforschung (GSI), Germany; Thoerle-Pospiech, P. [Johannes Gutenberg-Universitaet Mainz, Mainz, Germany; Torres, T. [Gesellschaft fur Schwerionenforschung (GSI), Germany; Traut, T. [Johannes Gutenberg-Universitaet Mainz, Mainz, Germany; Trautmann, N. [Johannes Gutenberg-Universitaet Mainz, Mainz, Germany; Tuerler, A. [Paul Scherrer Institut, Villigen, Switzerland; Ward, A. [University of Liverpool; Ward, D. E. [Lund University, Sweden; Wiehl, N. [Johannes Gutenberg-Universitaet Mainz, Mainz, Germany

2013-01-01T23:59:59.000Z

198

Results and Frontiers in Lattice Baryon Spectroscopy  

SciTech Connect

The Lattice Hadron Physics Collaboration (LHPC) baryon spectroscopy effort is reviewed. To date the LHPC has performed exploratory Lattice QCD calculations of the low-lying spectrum of Nucleon and Delta baryons. These calculations demonstrate the effectiveness of our method by obtaining the masses of an unprecedented number of excited states with definite quantum numbers. Future work of the project is outlined.

Bulava, John; Morningstar, Colin [Department of Physics, Carnegie Mellon University, Pittsburgh, PA 15213 (United States); Edwards, Robert; Richards, David [Thomas Jefferson National Accelerator Facility, Newport News, VA 23606 (United States); Fleming, George [Yale University New Haven, CT 06520 (United States); Juge, K. Jimmy [Department of Physics, University of the Pacific, Stockton, CA 95211 (United States); Lichtl, Adam C. [RBRC, Brookhaven National Laboratory, Upton, NY 11973 (United States); Mathur, Nilmani [Tata Institute of Fundamental Research, Mumbai 40005 (India); Wallace, Stephen J. [University of Maryland, College Park, MD 20742 (United States)

2007-10-26T23:59:59.000Z

199

Photoelectron Spectroscopy of U Oxide at LLNL  

Science Conference Proceedings (OSTI)

In our laboratory at LLNL, an effort is underway to investigate the underlying complexity of 5f electronic structure with spin-resolved photoelectron spectroscopy using chiral photonic excitation, i.e. Fano Spectroscopy. Our previous Fano measurements with Ce indicate the efficacy of this approach and theoretical calculations and spectral simulations suggest that Fano Spectroscopy may resolve the controversy concerning Pu electronic structure and electron correlation. To this end, we have constructed and commissioned a new Fano Spectrometer, testing it with the relativistic 5d system Pt. Here, our preliminary photoelectron spectra of the UO{sub 2} system are presented. X-ray photoelectron spectroscopy has been used to characterize a sample of UO{sub 2} grown on an underlying substrate of Uranium. Both AlK{alpha} (1487 eV) and MgK{alpha} (1254 eV) emission were utilized as the excitation. Using XPS and comparing to reference spectra, it has been shown that our sample is clearly UO{sub 2}.

Tobin, J G; Yu, S; Chung, B W; Waddill, G D

2010-03-02T23:59:59.000Z

200

Baryon spectroscopy with CLAS at Jefferson Lab  

Science Conference Proceedings (OSTI)

A substantial part of the experimental efforts at the experimental Hall-B of Jefferson Laboratory is dedicated to this studies of light baryon spectroscopy. In this report a general overview of the experimental capabilities in the Experimental Hall-B will be presented together with preliminary results of recent double polarization measurements and finally overall status of the program.

Eugene Pasyuk, CLAS Collaboration

2012-04-01T23:59:59.000Z

Note: This page contains sample records for the topic "angle-resolved photoemission spectroscopy" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


201

Extensions of quartz-enhanced photoacoustic spectroscopy  

E-Print Network (OSTI)

The goal of this thesis was to perform quartz-enhanced photoacoustic spectroscopy (QEPAS) on trace concentrations of NH3 in the 1.53 pm region with a DFB laser without the use of a resonating cavity. I analyzed the process ...

Masurkar, Amrita V

2009-01-01T23:59:59.000Z

202

Depth-resolved cathodoluminescence spectroscopy of silicon supersaturated with sulfur  

E-Print Network (OSTI)

We investigate the luminescence of Si supersaturated with S (Si:S) using depth-resolved cathodoluminescence spectroscopy and secondary ion mass spectroscopy as the S concentration is varied over 2 orders of magnitude ...

Fabbri, Filippo

203

Inhomogeneity and glass-forming ability in the bulk metallic glass Pd{sub 42.5}Ni{sub 7.5}Cu{sub 30}P{sub 20} as seen via x-ray spectroscopies  

Science Conference Proceedings (OSTI)

Core-level photoemission spectroscopy and anomalous x-ray scattering (AXS) measurements were performed for the Pd{sub 42.5}Ni{sub 7.5}Cu{sub 30}P{sub 20} (PNCP) excellent metallic glass to investigate the chemical nature and local atomic structure, and the results were compared to those in Pd{sub 40}Ni{sub 40}P{sub 20} and Pd{sub 40}Cu{sub 40}P{sub 20}. The P 2p core levels clearly separate into two states, indicating that the P atoms have two different chemical sites, which is a strong experimental proof for the existence of an elastic inhomogeneity. From the AXS close to the Pd K edge, a specific Pd-P-Pd atomic configuration was observed, which is related to the stable state in the P 2p core levels. All of the core levels measured in PNCP have the deepest binding energies among these glasses, indicating the most stable electronic states. Local structure around the P atoms is discussed by the AXS data and a metastable crystal appeared in a supercooled metallic alloy close to PNCP.

Hosokawa, S. [Center for Materials Research Using Third-Generation Synchrotron Radiation Facilities, Hiroshima Institute of Technology, Hiroshima 731-5193 (Japan); Physikalische Chemie, Fachbereich Chemie, Philipps Universitaet Marburg, D-35032 Marburg (Germany); Sato, H.; Nakatake, M. [Hiroshima Synchrotron Radiation Center, Hiroshima University, Higashi-Hiroshima 739-0046 (Japan); Ichitsubo, T.; Matsubara, E. [Department of Materials Science and Engineering, Graduate School of Engineering, Kyoto University, Kyoto 606-8501 (Japan); Happo, N. [Graduate School of Information Sciences, Hiroshima City University, Hiroshima 731-3194 (Japan); Berar, J.-F.; Boudet, N. [Institut Neel, CNRS, F-38042 Grenoble Cedex (France); Usuki, T. [Department of Material and Biological Chemistry, Faculty of Science, Yamagata University, Yamagata 990-8560 (Japan); Pilgrim, W.-C. [Physikalische Chemie, Fachbereich Chemie, Philipps Universitaet Marburg, D-35032 Marburg (Germany); Nishiyama, N. [R and D Institute of Metals and Composites for Future Industries, Sendai 980-8577 (Japan)

2009-11-01T23:59:59.000Z

204

Electric Cell-impedance Spectroscopy at the Biological-inorganic ...  

Science Conference Proceedings (OSTI)

Presentation Title, Electric Cell-impedance Spectroscopy at the Biological- inorganic Interface, Shewanella Oneidensis - Gold, for Microbial Fuel Cell ...

205

Time-resolved multiple probe spectroscopy  

SciTech Connect

Time-resolved multiple probe spectroscopy combines optical, electronic, and data acquisition capabilities to enable measurement of picosecond to millisecond time-resolved spectra within a single experiment, using a single activation pulse. This technology enables a wide range of dynamic processes to be studied on a single laser and sample system. The technique includes a 1 kHz pump, 10 kHz probe flash photolysis-like mode of acquisition (pump-probe-probe-probe, etc.), increasing the amount of information from each experiment. We demonstrate the capability of the instrument by measuring the photolysis of tungsten hexacarbonyl (W(CO){sub 6}) monitored by IR absorption spectroscopy, following picosecond vibrational cooling of product formation through to slower bimolecular diffusion reactions on the microsecond time scale.

Greetham, G. M.; Sole, D.; Clark, I. P.; Parker, A. W.; Pollard, M. R.; Towrie, M. [Central Laser Facility, Science and Technology Facilities Council, Research Complex at Harwell, Rutherford Appleton Laboratory, Harwell, Oxfordshire, OX11 0QX (United Kingdom)

2012-10-15T23:59:59.000Z

206

Charge exchange recombination spectroscopy on fusion devices  

Science Conference Proceedings (OSTI)

For fusion, obtaining reliable measurements of basic plasma parameters like ion and electron densities and temperatures is a primary goal. For theory, measurements are needed as a function of time and space to understand plasma transport and confinement with the ultimate goal of achieving economic nuclear fusion power. Electron profile measurements and plasma spectroscopy for the plasma ions are introduced. With the advent of Neutral Beam auxiliary plasma heating, Charge Exchange Recombination Spectroscopy provides accurate and time resolved measurements of the ions in large volume fusion devices. In acknowledgement of Nicol Peacock's role in the development of these techniques, still at the forefront of plasma fusion research, this paper describes the evolution of this diagnostic method.

Duval, B. P. [Centre de Recherches en Physique des Plasmas, EPFL, Lausanne (Switzerland)

2012-05-25T23:59:59.000Z

207

NIR Spectroscopy Development and Alternate Technology Uses  

Science Conference Proceedings (OSTI)

This report describes tests conducted to further develop a near-infrared (NIR) optical spectroscopy system designed to remotely detect corrosion on transmission line conductors. Besides evaluating the performance of the system on additional conductors, researchers refined the design of the prototype system in preparation for field testing.BackgroundCorrosion of the core of the aluminum conductor steel-reinforced (ACSR) conductors used in transmission lines is ...

2012-12-12T23:59:59.000Z

208

Photoelectron spectroscopy of supersonic molecular beams  

DOE Green Energy (OSTI)

A new technique for performing high resolution molecular photoelectron spectroscopy is described, beginning with its conceptual development, through the construction of a prototypal apparatus, to the initial applications on a particularly favorable molecular system. The distinguishing features of this technique are: (1) the introduction of the sample in the form of a collimated supersonic molecular beam; and (2) the use of an electrostatic deflection energy analyzer which is carefully optimized in terms of sensitivity and resolution. This combination makes it possible to obtain photoelectron spectra at a new level of detail for many small molecules. Three experiments are described which rely on the capability to perform rotationally-resolved photoelectron spectroscopy on the hydrogen molecule and its isotopes. The first is a measurement of the ionic vibrational and rotational spectroscopic constants and the vibrationally-selected photoionization cross sections. The second is a determination of the photoelectron asymmetry parameter, ..beta.., for selected rotational transitions. The third is an investigation of the rotational relaxation in a free jet expansion, using photoelectron spectroscopy as a probe of the rotational state population distributions. In the closing chapter an assessment is made of the successes and limitations of the technique, and an indication is given of areas for further improvement in future spectrometers.

Pollard, J.E.

1982-05-01T23:59:59.000Z

209

Issues in Light Meson Spectroscopy: The Case for Meson Spectroscopy at Cebaf  

E-Print Network (OSTI)

I review some outstanding issues in meson spectroscopy. The most important qualitative issue is whether hadrons with explicit gluonic degrees of freedom exist. To answer this question requires a much better understanding of conventional $q\\bar{q}$ mesons. I therefore begin by examining the status of conventional meson spectroscopy and how the situation can be improved. The expected properties of gluonic excitations are discussed with particular emphasis on hybrids to give guidance to experimental searches. Multiquark systems are commented upon as they are likely to be important in the mass region under study and will have to be understood better. In the final section I discuss the opportunities that CEBAF can offer for the study of meson spectroscopy.

Stephen Godfrey

1994-06-10T23:59:59.000Z

210

Center for Nanophase Materials Sciences (CNMS) - Imaging Functionality...  

NLE Websites -- All DOE Office Websites (Extended Search)

Laser MBE growth with high pressure RHEED for monitored growth of metals and oxides. LEED (Low Energy Electron Diffraction) UPS (Ultraviolet Photoemission Spectroscopy) and XPS...

211

Observations of Ferroelastic Switching by Raman Spectroscopy  

E-Print Network (OSTI)

Thermal barrier coatings (TBCs) have become an important part of turbine technology by providing thermal protection to the underlying metallic components. These coatings are typically made from a zirconia-based ceramics which have a low thermal conductivity and thermal expansion coefficients similar to those of the superalloys. Early failure in these coatings is most often due to foreign object damage and erosion resulting in delamination and spallation. To protect against these types of failure, new materials with increased toughness are needed. There are two main toughening mechanisms in ceramics: transformation toughening, which is limited to low temperature applications and ferroelastic toughening which is accessible at all temperatures. Ferroelastic toughening occurs when the c-axis of the tetragonal grain undergoes reorientation under the application of an external stress. In this study, ferroelastic toughening is examined by Raman spectroscopy. It is shown that by using polarized confocal Raman spectroscopy one can not only observed the ferroelastic process, but also measure the parameters that control the increase in toughness observed. Ferroelastic toughening was observed in two ways in the 18mol% ceria stabilized zirconia (18CSZ) samples studied here. Samples were either exposed to indentation damage or uniaxial loading. In both of these cases maps of the ceramic surface were taken using Raman spectroscopy following loading and the relative intensities of the tetragonal peaks were analyzed. The resulting intensity profiles were used to monitor the reorientation of domains corresponding to ferroelastic toughening. Changes in domain orientation were observed that corresponded to the reorientation of domains along cracks as well as on a larger scale along those cracks. Domain reorientation was also observed under uniaxial loading and the stresses required for domain formation and movement were measured.

Bolon, Amy Marie

2011-12-01T23:59:59.000Z

212

Photoionization electronic spectroscopy of AlAg  

Science Conference Proceedings (OSTI)

AlAg is produced in a supersonic molecular beam by laser vaporization of alloy samples in a pulsed nozzle cluster source. Electronic spectroscopy is studied with resonant two-photon photoionization. In addition to the two electronic excited states previously reported by Clements and Barrow, we have observed ten new states. Vibrational analyses are presented for each of these states, and rotational analyses are given for selected states. The number and characteristics of these excited states are compared to the predictions of recent [ital ab] [ital initio] calculations.

Robbins, D.L.; Yeh, C.S.; Pilgrim, J.S.; Lang, G.L.; Duncan, M.A. (Department of Chemistry, University of Georgia, Athens, Georgia 30602 (United States))

1994-04-01T23:59:59.000Z

213

High-resolution flurescence spectroscopy in immunoanalysis  

SciTech Connect

The work presented in this dissertation combines highly sensitive and selective fluorescence line-narrowing spectroscopy (FLNS) detection with various modes of immunoanalytical techniques. It has been shown that FLNS is capable of directly probing molecules immunocomplexed with antibodies, eliminating analytical ambiguities that may arise from interferences that accompany traditional immunochemical techniques. Moreover, the utilization of highly cross-reactive antibodies for highly specific analyte determination has been demonstrated. Finally, they demonstrate the first example of the spectral resolution of diastereomeric analytes based on their interaction with a cross-reactive antibody.

Grubor, Nenad M.

2005-05-01T23:59:59.000Z

214

Integral-field spectroscopy of SLACS lenses  

E-Print Network (OSTI)

The combination of two-dimensional kinematics and gravitational lens modelling permits detailed reconstruction of the phase-space structure of early-type galaxies and sets constraints on the dark-matter distribution in their inner regions. We describe a project which combines integral-field spectroscopy from an ESO Large Programme using VIMOS on the VLT with deep HST ACS and NICMOS images to study a sample of 17 early-type lens galaxies at redshifts between 0.1 and 0.3, drawn from the Sloan Lens ACS survey (SLACS).

Oliver Czoske; Matteo Barnabe; Leon Koopmans

2008-11-14T23:59:59.000Z

215

Light Meson Spectroscopy with the Kloe Experiment  

E-Print Network (OSTI)

We describe the status of the analyses in progress on light meson spectroscopy in the KLOE experiment. We present the analyses of phi decays into f0(980)gamma and a0(980)gamma, the Dalitz plot analysis of the eta to pie+ pie- pie0 decay, the branching ratio measurement of eta to pie0 gamma gamma, the upper limits on Br(eta to 3 gamma) and Br(eta to pie^+ pie^-), the measurement of the ratio Br(phi to eta' gamma)/Br(phi to eta gamma) and phi leptonic width measurements.

The KLOE collaboration; B. Di Micco

2004-10-25T23:59:59.000Z

216

Cavity-locked ring down spectroscopy  

DOE Patents (OSTI)

Distinct locking and sampling light beams are used in a cavity ring-down spectroscopy (CRDS) system to perform multiple ring-down measurements while the laser and ring-down cavity are continuously locked. The sampling and locking light beams have different frequencies, to ensure that the sampling and locking light are decoupled within the cavity. Preferably, the ring-down cavity is ring-shaped, the sampling light is s-polarized, and the locking light is p-polarized. Transmitted sampling light is used for ring-down measurements, while reflected locking light is used for locking in a Pound-Drever scheme.

Zare, Richard N. (Stanford, CA); Paldus, Barbara A. (Stanford, CA); Harb, Charles C. (Palo Alto, CA); Spence, Thomas (Union City, CA)

2000-01-01T23:59:59.000Z

217

Precision spectroscopy of the helium atom.  

SciTech Connect

Persistent efforts in both theory and experiment have yielded increasingly precise understanding of the helium atom. Because of its simplicity, the helium atom has long been a testing ground for relativistic and quantum electrodynamic effects in few-body atomic systems theoretically and experimentally. Comparison between theory and experiment of the helium spectroscopy in 1s2p{sup 3}P{sub J} can potentially extract a very precise value of the fine structure constant a. The helium atom can also be used to explore exotic nuclear structures. In this paper, we provide a brief review of the recent advances in precision calculations and measurements of the helium atom.

Hu, S.-M.; Lu, Z.-T.; Yan, Z.-C.; Physics; Univ. of Science and Technology of China; Univ. of Chicago; Univ. of New Brunswick

2009-06-01T23:59:59.000Z

218

Anomalous mass enhancement in strongly-correlated quantum wells  

Science Conference Proceedings (OSTI)

We investigate the electronic properties of quantum wells consisting of a t1 2g-electron system with strong correlations using dynamical-mean-eld theory. The special focus is on the subband structure of such quantum wells. The effective mass is found to increase with increasing the bottom of the subband, i.e., decreasing the subband occupation number. This is due to the combination of Coulomb repulsion, whose effect is enhanced on surface layers, and longer-range hoppings. We discuss the implication of these results for the recent angle-resolved photoemission experiment on SrVO3 thin lms.

Okamoto, Satoshi [ORNL

2011-01-01T23:59:59.000Z

219

Robust surface electronic properties of topological insulators: Bi{sub 2}Te{sub 3} films grown by molecular beam epitaxy  

Science Conference Proceedings (OSTI)

The surface electronic properties of the important topological insulator Bi{sub 2}Te{sub 3} are shown to be robust under an extended surface preparation procedure, which includes exposure to atmosphere and subsequent cleaning and recrystallization by an optimized in situ sputter-anneal procedure under ultrahigh vacuum conditions. Clear Dirac-cone features are displayed in high-resolution angle-resolved photoemission spectra from the resulting samples, indicating remarkable insensitivity of the topological surface state to cleaning-induced surface roughness.

Plucinski, L.; Herdt, A. [Peter Gruenberg Institut (PGI-6), Forschungszentrum Juelich, D-52425 Juelich (Germany); Mussler, G.; Krumrain, J.; Gruetzmacher, D. [Peter Gruenberg Institut (PGI-9), Forschungszentrum Juelich, D-52425 Juelich (Germany); Juelich Aachen Research Alliance-Fundamentals of Future Information Technologies (JARA-FIT), D-52425 Juelich (Germany); Suga, S. [Peter Gruenberg Institut (PGI-6), Forschungszentrum Juelich, D-52425 Juelich (Germany); Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531 (Japan); Schneider, C. M. [Peter Gruenberg Institut (PGI-6), Forschungszentrum Juelich, D-52425 Juelich (Germany); Juelich Aachen Research Alliance-Fundamentals of Future Information Technologies (JARA-FIT), D-52425 Juelich (Germany)

2011-05-30T23:59:59.000Z

220

Study of clusters using negative ion photodetachment spectroscopy  

SciTech Connect

The weak van der Waals interaction between an open-shell halogen atom and a closed-shell atom or molecule has been investigated using zero electron kinetic energy (ZEKE) spectroscopy. This technique is also applied to study the low-lying electronic states in GaAs and GaAs{sup {minus}}. In addition, the spectroscopy and electron detachment dynamics of several small carbon cluster anions are studied using resonant multiphoton detachment spectroscopy.

Zhao, Yuexing

1995-12-01T23:59:59.000Z

Note: This page contains sample records for the topic "angle-resolved photoemission spectroscopy" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


221

Application of QCLs to ns IR Spectroscopy Following Pulse Radiolysis  

NLE Websites -- All DOE Office Websites (Extended Search)

External-Cavity Quantum Cascade Infrared Lasers to Nanosecond Time-Resolved Infrared Spectroscopy of Condensed-Phase Samples Following Pulse Radiolysis David C. Grills, Andrew R....

222

Coherent Anti-Stokes Raman Spectroscopy (CARS) - Available ...  

Search PNNL. PNNL Home; About; Research; Publications; Jobs; News; Contacts; Coherent Anti-Stokes Raman Spectroscopy (CARS) Battelle Number(s): 11982. ...

223

Symmetry-Breaking Orbital Anisotropy Observed for Detwinned Ba(Fe1-xCox)2As2 above the Spin Density Wave Transition  

SciTech Connect

Nematicity, defined as broken rotational symmetry, has recently been observed in competing phases proximate to the superconducting phase in the cuprate high temperature superconductors. Similarly, the new iron-based high temperature superconductors exhibit a tetragonal to orthorhombic structural transition (i.e. a broken C{sub 4} symmetry) that either precedes or is coincident with a collinear spin density wave (SDW) transition in undoped parent compounds, and superconductivity arises when both transitions are suppressed via doping. Evidence for strong in-plane anisotropy in the SDW state in this family of compounds has been reported by neutron scattering, scanning tunneling microscopy, and transport measurements. Here we present an angle resolved photoemission spectroscopy study of detwinned single crystals of a representative family of electron-doped iron-arsenide superconductors, Ba(Fe{sub 1-x}Co{sub x}){sub 2}As{sub 2} in the underdoped region. The crystals were detwinned via application of in-plane uniaxial stress, enabling measurements of single domain electronic structure in the orthorhombic state. At low temperatures, our results clearly demonstrate an in-plane electronic anisotropy characterized by a large energy splitting of two orthogonal bands with dominant d{sub xz} and d{sub yz} character, which is consistent with anisotropy observed by other probes. For compositions x > 0, for which the structural transition (T{sub S}) precedes the magnetic transition (T{sub SDW}), an anisotropic splitting is observed to develop above T{sub SDW}, indicating that it is specifically associated with T{sub S}. For unstressed crystals, the band splitting is observed close to T{sub S}, whereas for stressed crystals the splitting is observed to considerably higher temperatures, revealing the presence of a surprisingly large in-plane nematic susceptibility in the electronic structure.

Yi, Ming

2011-08-19T23:59:59.000Z

224

Quantitative Spectroscopy of BA-type Supergiants  

E-Print Network (OSTI)

Luminous BA-SGs allow topics ranging from NLTE physics and the evolution of massive stars to the chemical evolution of galaxies and cosmology to be addressed. A hybrid NLTE technique for the quantitative spectroscopy of BA-SGs is discussed. Thorough tests and first applications of the spectrum synthesis method are presented for four bright Galactic objects. Stellar parameters are derived from spectroscopic indicators. The internal accuracy of the method allows the 1sigma-uncertainties to be reduced to reduce random errors and remove systematic trends in the analysis. Inappropriate LTE analyses tend to systematically underestimate iron group abundances and overestimate the light and alpha-process element abundances by up to factors of 2-3 on the mean. Contrary to common assumptions, significant NLTE abundance correction...

Przybilla, N; Becker, S R; Kudritzki, R P

2005-01-01T23:59:59.000Z

225

New developments in IR surface vibrational spectroscopy  

DOE Green Energy (OSTI)

Low frequency dynamics at surfaces, particularly in the region of the adsorbate-substrate vibrational modes is of fundamental importance in areas as varied as sliding friction, catalysis, corrosion and epitaxial growth. This paper reviews the new developments in low frequency Infrared Reflection Absorption Spectroscopy using synchrotron radiation as the source. Absolute changes induced in the far infrared for several adsorbate systems on Cu, including CO and H, are dominated by broadband reflectance changes and dipole forbidden vibrational modes which in some cases are an order of magnitude stronger than the dipole allowed modes. The experimental data can be explained by a theory developed by Persson, in which the dielectric response of the substrate is seen as playing a crucial role in the dynamics. In particular the relationships between the wavelength of the light, the penetration depth and the electron mean-free path, are critical.

Hirschmugl, C.J.; Lamont, C.L.A.; Williams, G.P. [Brookhaven National Lab., Upton, NY (United States). National Synchrotron Light Source

1995-12-31T23:59:59.000Z

226

Delta, iota and other meson spectroscopies  

Science Conference Proceedings (OSTI)

This talk is given from the point of view of an experimentalist. Meson spectroscopy in the 1 to 3 GeV region is interesting because experiments exploring this region, in particular radiative psi decay, have found a rich structure of resonances too complicated to unravel with any one experiment, and not easily interpreted with any one theoretical model. None of the theoretical calculations predicting all kinds of interesting and exotic objects in this region is very convincing or reliable. Additional input from anti pp annihilation can be very useful in helping to find the answers to the following open questions: what exactly is this spectrum, what are the masses and quantum numbers of the resonances, as determined from analysis of data without theoretical prejudices; how is this spectrum described by QCD, is there evidence for new kinds of states like glue-balls, hybrids, axions, Higgses or multiquark exotics, and is there any evidence for new physics beyond QCD. 20 refs.

Lipkin, H.J.

1986-05-01T23:59:59.000Z

227

Remote Adjustable focus Raman Spectroscopy Probe  

DOE Patents (OSTI)

A remote adjustable focus Raman spectroscopy probe allows for analyzing Raman scattered light from a point of interest external to the probe. An environmental barrier including at least one window separates the probe from the point of interest. An optical tube is disposed adjacent to the environmental barrier and includes along working length compound lens objective next to the window. A beam splitter and a mirror are at the other end. A mechanical means is used to translate the probe body in the X, Y, and Z directions resulting in a variable focus optical apparatus. Laser light is reflected by the beam splitter and directed toward the compound lens objective, then through the window and focused on the point of interest. Raman scattered light is then collected by the compound lens objective and directed through the beam splitter to a mirror. A device for analyzing the light, such as a monochrometer, is coupled to the mirror.

Schmucker, John E.; Blasi, Raymond J.; Archer, William B.

1998-07-28T23:59:59.000Z

228

Anion photoelectron spectroscopy of radicals and clusters  

SciTech Connect

Anion photoelectron spectroscopy is used to study free radicals and clusters. The low-lying {sup 2}{Sigma} and {sup 2}{Pi} states of C{sub 2n}H (n = 1--4) have been studied. The anion photoelectron spectra yielded electron affinities, term values, and vibrational frequencies for these combustion and astrophysically relevant species. Photoelectron angular distributions allowed the author to correctly assign the electronic symmetry of the ground and first excited states and to assess the degree of vibronic coupling in C{sub 2}H and C{sub 4}H. Other radicals studied include NCN and I{sub 3}. The author was able to observe the low-lying singlet and triplet states of NCN for the first time. Measurement of the electron affinity of I{sub 3} revealed that it has a bound ground state and attachment of an argon atom to this moiety enabled him to resolve the symmetric stretching progression.

Travis, Taylor R.

1999-12-16T23:59:59.000Z

229

Remote adjustable focus Raman spectroscopy probe  

DOE Patents (OSTI)

A remote adjustable focus Raman spectroscopy probe allows for analyzing Raman scattered light from a point of interest external probe. An environmental barrier including at least one window separates the probe from the point of interest. An optical tube is disposed adjacent to the environmental barrier and includes a long working length compound lens objective next to the window. A beam splitter and a mirror are at the other end. A mechanical means is used to translated the prove body in the X, Y, and Z directions resulting in a variable focus optical apparatus. Laser light is reflected by the beam splitter and directed toward the compound lens objective, then through the window and focused on the point of interest. Raman scattered light is then collected by the compound lens objective and directed through the beam splitter to a mirror. A device for analyzing the light, such as a monochrometer, is coupled to the mirror.

Schmucker, John E. (Hurt, VA); Blasi, Raymond J. (Harrison City, PA); Archer, William B. (Bethel Park, PA)

1999-01-01T23:59:59.000Z

230

Spectroscopy, Kinetics, and Dynamics of Combustion Radicals  

SciTech Connect

Spectroscopy, kinetics and dynamics of jet cooled hydrocarbon transients relevant to the DOE combustion mission have been explored, exploiting i) high resolution IR lasers, ii) slit discharge sources for formation of jet cooled radicals, and iii) high sensitivity detection with direct laser absorption methods and near the quantum shot noise limit. What makes this combination powerful is that such transients can be made under high concentrations and pressures characteristic of actual combustion conditions, and yet with the resulting species rapidly cooled (T ?10-15K) in the slit supersonic expansion. Combined with the power of IR laser absorption methods, this provides novel access to spectral detection and study of many critical combustion species.

Nesbitt, David J. [Research/Professor

2013-08-06T23:59:59.000Z

231

VALENCE BAND PHOTOEMISSION STUDIES OF CLEAN METALS  

E-Print Network (OSTI)

Radiation Laboratory (SSRL), reported in Chapters III andfrom laboratory sources. SSRL (8) has the capability ofthe 4° port of Beam Line I at SSRL. The grazing incidence

Wehner, Paul Sherman

2011-01-01T23:59:59.000Z

232

Core Level Spectroscopies Surface Science and X-Ray Spectroscopy Group  

NLE Websites -- All DOE Office Websites (Extended Search)

Core Level Spectroscopy Creation and Decay of Core Holes Spectroscopic Techniques X-ray Photoelectron (XPS) X-ray Absorption (XAS) X-ray Emission (XES) Auger Electron (AES) Core holes are created by the ionization of a core electron in XPS and by excitation in XAS . The XPS and XAS final states are highly unstable and the core hole decays by non-radiant Auger relaxation (AES) or by radiant x-ray emission processes (XES). XPS and AES probe the unoccupied electronic stru cture, while XAS projects the unoccupied valence states of the system onto a particular atom. A brief description of the each of the different spectroscopies illustrated by schematic pictures of the creation and decay with data measured for N2 adsorbed on Ni(100) can be found by scrolling

233

Guanine tautomerism revealed by UVUV and IRUV hole burning spectroscopy  

E-Print Network (OSTI)

Guanine tautomerism revealed by UV­UV and IR­UV hole burning spectroscopy E. Nir Department spectroscopy. 1-methylguanine, in which the Keto­Enol tautomerism is blocked, shows hole burning spectra from hole burning SHB by using two counter- propagating dye laser pulses with a delay of about 150 ns

de Vries, Mattanjah S.

234

On spectroscopy for a whole Abelian model  

Science Conference Proceedings (OSTI)

Postulated on the whole meaning a whole abelian gauge symmetry is being introduced. Various physical areas as complexity, statistical mechanics, quantum mechanics are partially supporting this approach where the whole is at origin. However, the reductionist crisis given by quark confinement definitely sustains this insight. It says that fundamental parts can not be seen isolatedely. Consequently, there is an experimental situation where the parts should be substituted by something more. This makes us to look for writing the wholeness principle under gauge theory. For this, one reinterprets the gauge parameter where instead of compensating fields it is organizing a systemic gauge symmetry. Now, it introduces a fields set {l_brace}A{sub {mu}I}{r_brace} rotating under a common gauge symmetry. Thus, given a fields collection {l_brace}A{sub {mu}I}{r_brace} as origin, the effort at this work is to investigate on its spectroscopy. Analyze for the abelian case the correspondent involved quanta. Understand that for a whole model diversity replaces elementarity. Derive the associated quantum numbers as spin, mass, charge, discrete symmetries in terms of such systemic symmetry. Observe how the particles diversity is manifested in terms of wholeness.

Chauca, J.; Doria, R. [CBPF, Rio de Janeiro (Brazil); Aprendanet, Petropolis, 25600 (Brazil)

2012-09-24T23:59:59.000Z

235

Probing brain oxygenation with near infrared spectroscopy  

E-Print Network (OSTI)

The fundamentals of near infrared spectroscopy (NIRS) are reviewed. This technique allows to measure the oxygenation of the brain tissue. The particular problems involved in detecting regional brain oxygenation (rSO2) are discussed. The dominant chromophore (light absorber) in tissue is water. Only in the NIR light region of 650-1000 nm, the overall absorption is sufficiently low, and the NIR light can be detected across a thick layer of tissues, among them the skin, the scull and the brain. In this region, there are many absorbing light chromophores, but only three are important as far as the oxygenation is concerned. They are the hemoglobin (HbO2), the deoxy-hemoglobin (Hb) and cytochrome oxidase (CtOx). In the last 20 years there was an enormous growth in the instrumentation and applications of NIRS. . The devices that were used in our experiments were : Somanetics's INVOS Brain Oximeter (IBO) and Toomim's HEG spectrophotometer. The performances of both devices were compared including their merits and draw...

Gersten, Alexander; Raz, Amir; Fried, Robert

2011-01-01T23:59:59.000Z

236

Ultrafast thin-film laser-induced breakdown spectroscopy of doped...  

NLE Websites -- All DOE Office Websites (Extended Search)

Ultrafast thin-film laser-induced breakdown spectroscopy of doped oxides Title Ultrafast thin-film laser-induced breakdown spectroscopy of doped oxides Publication Type Journal...

237

EXPERIMENTS ON SELECTIVE EXCITATION OF MULTIPLE-QUANTUM TRANSITIONS IN NMR SPECTROSCOPY  

E-Print Network (OSTI)

M. Mehring, High Resolution NMR Spectroscopy in Solids (sequences for producing quantum NMR spectra. multiple~ InMULTIPLE-QUANTUM TRANSITIONS IN NMR SPECTROSCOPY W.S. Warren

Warren, W.S.

2013-01-01T23:59:59.000Z

238

Bimolecular reaction dynamics from photoelectron spectroscopy of negative ions  

DOE Green Energy (OSTI)

The transition state region of a neutral bimolecular reaction may be experimentally investigated by photoelectron spectroscopy of an appropriate negative ion. The photoelectron spectrum provides information on the spectroscopy and dynamics of the short lived transition state and may be used to develop model potential energy surfaces that are semi-quantitative in this important region. The principles of bound [yields] bound negative ion photoelectron spectroscopy are illustrated by way of an example: a full analysis of the photoelectron bands of CN[sup [minus

Bradforth, S.E.

1992-11-01T23:59:59.000Z

239

Neutrino Spectroscopy with Atoms and Molecules  

E-Print Network (OSTI)

We give a comprehensive account of our proposed experimental method of using atoms or molecules in order to measure parameters of neutrinos still undetermined; the absolute mass scale, the mass hierarchy pattern (normal or inverted), the neutrino mass type (Majorana or Dirac), and the CP violating phases including Majorana phases. There are advantages of atomic targets, due to the closeness of available atomic energies to anticipated neutrino masses, over nuclear target experiments. Disadvantage of using atomic targets, the smallness of rates, is overcome by the macro-coherent amplification mechanism. The atomic or molecular process we use is a cooperative deexcitation of a collective body of atoms in a metastable level |e> emitting a neutrino pair and a photon; |e> -> |g> + gamma + nu_i nu_j where nu_i's are neutrino mass eigenstates. The macro-coherence is developed by trigger laser irradiation. We discuss aspects of the macro-coherence development by setting up the master equation for the target quantum state and propagating electric field. With a choice of heavy target atom or molecule such as Xe or I_2 that has a large M1 x E1 matrix element between |e> and |g>, we show that one can determine three neutrino masses along with the mass hierarchy pattern by measuring the photon spectral shape. If one uses a target of available energy of a fraction of 1 eV, Majorana CP phases may be determined. Our master equation, when applied to E1 x E1 transition such as pH_2 vibrational transition Xv=1 -> 0, can describe explosive PSR events in which most of the energy stored in |e> is released within a few nanoseconds. The present paper is intended to be self-contained explaining some details related theoretical works in the past, and further reports new simulations and our ongoing experimental efforts of the project to realize the neutrino mass spectroscopy using atoms/molecules.

Atsushi Fukumi; Susumu Kuma; Yuki Miyamoto; Kyo Nakajima; Itsuo Nakano; Hajime Nanjo; Chiaki Ohae; Noboru Sasao; Minoru Tanaka; Takashi Taniguchi; Satoshi Uetake; Tomonari Wakabayashi; Takuya Yamaguchi; Akihiro Yoshimi; Motohiko Yoshimura

2012-11-21T23:59:59.000Z

240

Magnetic spectroscopy and microscopy of functional materials  

SciTech Connect

Heusler intermetallics Mn{sub 2}Y Ga and X{sub 2}MnGa (X; Y =Fe, Co, Ni) undergo tetragonal magnetostructural transitions that can result in half metallicity, magnetic shape memory, or the magnetocaloric effect. Understanding the magnetism and magnetic behavior in functional materials is often the most direct route to being able to optimize current materials for todays applications and to design novel ones for tomorrow. Synchrotron soft x-ray magnetic spectromicroscopy techniques are well suited to explore the the competing effects from the magnetization and the lattice parameters in these materials as they provide detailed element-, valence-, and site-specifc information on the coupling of crystallographic ordering and electronic structure as well as external parameters like temperature and pressure on the bonding and exchange. Fundamental work preparing the model systems of spintronic, multiferroic, and energy-related compositions is presented for context. The methodology of synchrotron spectroscopy is presented and applied to not only magnetic characterization but also of developing a systematic screening method for future examples of materials exhibiting any of the above effects. The chapter progression is as follows: an introduction to the concepts and materials under consideration (Chapter 1); an overview of sample preparation techniques and results, and the kinds of characterization methods employed (Chapter 2); spectro- and microscopic explorations of X{sub 2}MnGa/Ge (Chapter 3); spectroscopic investigations of the composition series Mn{sub 2}Y Ga to the logical Mn{sub 3}Ga endpoint (Chapter 4); and a summary and overview of upcoming work (Chapter 5). Appendices include the results of a Think Tank for the Graduate School of Excellence MAINZ (Appendix A) and details of an imaging project now in progress on magnetic reversal and domain wall observation in the classical Heusler material Co{sub 2}FeSi (Appendix B).

Jenkins, C.A.

2011-01-28T23:59:59.000Z

Note: This page contains sample records for the topic "angle-resolved photoemission spectroscopy" from the National Library of EnergyBeta (NLEBeta).
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241

Broadband Dielectric Spectroscopy on Human Blood  

E-Print Network (OSTI)

Dielectric spectra of human blood reveal a rich variety of dynamic processes. Achieving a better characterization and understanding of these processes not only is of academic interest but also of high relevance for medical applications as, e.g., the determination of absorption rates of electromagnetic radiation by the human body. The dielectric properties of human blood are studied using broadband dielectric spectroscopy, systematically investigating the dependence on temperature and hematocrit value. By covering a frequency range from 1 Hz to 40 GHz, information on all the typical dispersion regions of biological matter is obtained. We find no evidence for a low-frequency relaxation (alpha-relaxation) caused, e.g., by counterion diffusion effects as reported for some types of biological matter. The analysis of a strong Maxwell-Wagner relaxation arising from the polarization of the cell membranes in the 1-100 MHz region (beta-relaxation) allows for the test of model predictions and the determination of various intrinsic cell properties. In the microwave region beyond 1 GHz, the reorientational motion of water molecules in the blood plasma leads to another relaxation feature (gamma-relaxation). Between beta- and gamma-relaxation, significant dispersion is observed, which, however, can be explained by a superposition of these relaxation processes and is not due to an additional delta-relaxation often found in biological matter. Our measurements provide dielectric data on human blood of so far unsurpassed precision for a broad parameter range. All data are provided in electronic form to serve as basis for the calculation of the absorption rate of electromagnetic radiation and other medical purposes. Moreover, by investigating an exceptionally broad frequency range, valuable new information on the dynamic processes in blood is obtained.

M. Wolf; R. Gulich; P. Lunkenheimer; A. Loidl

2011-05-25T23:59:59.000Z

242

Nonlinear optical spectroscopy of diamond surfaces  

DOE Green Energy (OSTI)

Second harmonic generation (SHG) and infrared-visible sum frequency generation (SFG) spectroscopies have been shown to be powerful and versatile for studying surfaces with submonolayer sensitivity. They have been used in this work to study bare diamond surfaces and molecular adsorption on them. In particular, infrared-visible SFG as a surface vibrational spectroscopic technique has been employed to identify and monitor in-situ surface bonds and species on the diamond (111) surface. The CH stretch spectra allow us to investigate hydrogen adsorption, desorption, abstraction, and the nature of the hydrogen termination. The C(111) surface dosed with atomic hydrogen was found to be in a monohydride configuration with the hydrogen atoms situated at top-sites. The ratio of the abstraction rate to the adsorption rate was appreciable during atomic hydrogen dosing. Kinetic parameters for thermal desorption of H on C(111) were determined showing a near first-order kinetics. For the fully H-terminated (111) surface, a large (110 cm{sup {minus}1}) anharmonicity and {approximately}19 psec lifetime were measured for the first-excited CH stretch mode. The bare reconstructed C(111)-(2 {times} l) surface showed the presence of CC stretch modes which were consistent with the Pandey {pi}-bonded chain structure. When exposed to the methyl radical, the SFG spectra of the C(111) surface showed features suggesting the presence of adsorbed methyl species. After heating to sufficiently high temperatures, they were converted into the monohydride species. Preliminary results on the hydrogen-terminated diamond (100) surface are also presented.

Chin, R.P.

1995-04-01T23:59:59.000Z

243

FRONTIER SYNCHROTRON INFRARED SPECTROSCOPY BEAMLINE UNDER EXTREME CONDITIONS (FIS)  

NLE Websites -- All DOE Office Websites (Extended Search)

FRONTIER SYNCHROTRON INFRARED SPECTROSCOPY FRONTIER SYNCHROTRON INFRARED SPECTROSCOPY BEAMLINE UNDER EXTREME CONDITIONS (FIS) Proposal Team: L. Carr 1 , D. Dolan 2 , R. Hemley 3 , S. Jacobson 4 , S. Karato 5 , Z. Liu 3 , W. Panero 6 , M. Pravica 7 , and T. Zhou 8 1 Brookhaven National Laboratory, 2 Sandia National Laboratories, 3 Carnegie Institution of Washington, 4 Northwestern University, 5 Yale University, 6 Ohio State University, 7 University of Nevada, 8 New Jersey Institute of Technology TECHNIQUES AND CAPABILITIES APPLICATIONS SPECIFIC PROJECTS / ADDITIONAL INFORMATION * TECHNIQUE(S): Fourier transform infrared spectroscopy; Raman and visible spectroscopy; Diamond anvil cell techniques for static high pressure; Gas-gun launchers for dynamic compression; Cryogenic techniques combined with DACs;

244

Raman Spectroscopy of High Thermal Conductivity AlN Ceramics ...  

Science Conference Proceedings (OSTI)

Thermal conductivity of AlN ceramics was measured by laser flash method. Raman spectroscopy was used to characterize oxygen related defects of AlN ... Transport in Co-Based Materials for Fuel Cells and Oxygen Separation Membranes.

245

Fourier Transform Infrared Spectroscopy for Process Monitoring and Control  

E-Print Network (OSTI)

This paper discusses recent applications of FT-IR spectroscopy to measure gas concentrations and temperatures, and particle sizes. Advances in hardware are discussed and results for field tests in pulp and paper and utility boilers are presented.

Solomon, P. R.; Carangelo, M. D.; Carangelo, R. M.

1994-04-01T23:59:59.000Z

246

Microwave quantum logic spectroscopy and control of molecular ions  

E-Print Network (OSTI)

A general method for rotational microwave spectroscopy and control of polar molecular ions via direct microwave addressing is considered. Our method makes use of spatially varying ac Stark shifts, induced by far off-resonant, ...

Drewsen, M

247

Radio-frequency spectroscopy of ultracold atomic Fermi gases  

E-Print Network (OSTI)

This thesis presents experiments investigating the phase diagram of ultracold atomic Fermi gases using radio-frequency spectroscopy. The tunability of many experimental parameters including the temperature, the interparticle ...

Schirotzek, Andre

2010-01-01T23:59:59.000Z

248

Precision spectroscopy by photon-recoil signal amplification  

E-Print Network (OSTI)

Precision spectroscopy of atomic and molecular ions offers a window to new physics, but is typically limited to species with a cycling transition for laser cooling and detection. Quantum logic spectroscopy has overcome this limitation for species with long-lived excited states. Here, we extend quantum logic spectroscopy to fast, dipole-allowed transitions and apply it to perform an absolute frequency measurement. We detect the absorption of photons by the spectroscopically investigated ion through the photon recoil imparted on a co-trapped ion of a different species, on which we can perform efficient quantum logic detection techniques. This amplifies the recoil signal from a few absorbed photons to thousands of fluorescence photons. We resolve the line center of a dipole-allowed transition in 40Ca+ to 1/300 of its observed linewidth, rendering this measurement one of the most accurate of a broad transition. The simplicity and versatility of this approach enables spectroscopy of many previously inaccessible species.

Yong Wan; Florian Gebert; Jannes B. Wübbena; Nils Scharnhorst; Sana Amairi; Ian D. Leroux; Börge Hemmerling; Niels Lörch; Klemens Hammerer; Piet O. Schmidt

2013-09-26T23:59:59.000Z

249

Dirac Charge Dynamcs in Graphene by Infrared Spectroscopy  

NLE Websites -- All DOE Office Websites (Extended Search)

Dirac Charge Dynamcs in Graphene by Infrared Spectroscopy Print Graphene-a single layer of carbon atoms arranged in a honeycomb lattice-has very high conductivity that can be tuned...

250

Microsoft PowerPoint - SpectroscopyTechniques_XANES  

NLE Websites -- All DOE Office Websites (Extended Search)

Near Edge Spectroscopy (XANES) Near Edge Spectroscopy (XANES) XANES: XANES: * Element specific * Highly sensitive to bond angles, bond lengths, and the presence of adsorbates NEXAFS (Near Edge X-ray Absorption Fine Structure): * Synonymous with XANES but soft x-ray spectroscopy (< 1keV) * Fine structure within about 30 eV of the absorption edge EXAFS XANES / XRD C bi i S EXAFS-XANES / XRD Combination Spectroscopy * XAFS-XANES and XRD techniques give complementary information about the structure of materials. * XRD is effective in materials with medium- to long-range A typical XANES Spectrum XRD is effective in materials with medium to long range order while XAFS provides short-range information. *The simultaneous collection of the XRD and XAFS- XANES data in situ will allow

251

Ultrafast laser induced breakdown spectroscopy of electrode/electrolyte  

NLE Websites -- All DOE Office Websites (Extended Search)

Ultrafast laser induced breakdown spectroscopy of electrode/electrolyte Ultrafast laser induced breakdown spectroscopy of electrode/electrolyte interfaces Title Ultrafast laser induced breakdown spectroscopy of electrode/electrolyte interfaces Publication Type Journal Article Year of Publication 2012 Authors Zormpa, Vasileia, Jaroslaw Syzdek, Xianglei Mao, Richard E. Russo, and Robert Kostecki Journal Applied Physics Letters Volume 100 Issue 23 Date Published 05-2012 ISSN 0003-6951 Keywords electrochemical electrodes, graphite, high-speed optical techniques, laser beam effects, organic compounds, pyrolysis, solid electrolytes Abstract Direct chemical analysis of electrode/electrolyte interfaces can provide critical information on surface phenomena that define and control the performance of Li-based battery systems. In this work, we introduce the use of ex situ femtosecond laser induced breakdown spectroscopy to probe compositional variations within the solid electrolyte interphase (SEI) layer. Nanometer-scale depth resolution was achieved for elemental and molecular depth profiling of SEI layers formed on highly oriented pyrolytic graphite electrodes in an organic carbonate-based electrolyte. This work demonstrates the unique ability of ultrafast laser spectroscopy as a highly versatile, light element-sensitive technique for direct chemical analysis of interfacial layers in electrochemical energy storage systems.

252

Double pulse laser induced breakdown spectroscopy; experimental study of  

NLE Websites -- All DOE Office Websites (Extended Search)

Double pulse laser induced breakdown spectroscopy; experimental study of Double pulse laser induced breakdown spectroscopy; experimental study of lead emission intensity dependence on the wavelengths and sample matrix Title Double pulse laser induced breakdown spectroscopy; experimental study of lead emission intensity dependence on the wavelengths and sample matrix Publication Type Journal Article Year of Publication 2009 Authors Piscitelli, Vincent, Mauro A. Martinez, Alberto J. Fernandez, Jhanis J. Gonzalez, Xianglei Mao, and Richard E. Russo Journal Spectrochimica Acta Part B Volume 64 Issue 2 Pagination 147-154 Date Published 02/2009 Keywords Double pulse LIBS, laser induced breakdown spectroscopy, lead Abstract Lead (Pb) emission intensity (atomic line 405.78 nm) dependence on the sample matrix (metal alloy) was studied by means of collinear double pulse (DP)-laser induced breakdown spectroscopy (LIBS). The measurement of the emission intensity produced by three different wavelength combinations (i.e. I:532 nm-II:1064 nm, I:532 nm-II:532 nm, and I:532 nm-II:355 nm) from three series of standard reference materials showed that the lead atomic line 405.78 nm emission intensity was dependent on the sample matrix for all the combination of wavelengths, however reduced dependency was found for the wavelength combination I:532 nm-II:355 nm.

253

INFRARED ABSORPTION SPECTROSCOPY AND CHEMICAL KINETICS OF FREE RADICALS  

NLE Websites -- All DOE Office Websites (Extended Search)

mNAL PERFORMANCE REPORT mNAL PERFORMANCE REPORT for INFRARED ABSORPTION SPECTROSCOPY AND CHEMICAL KINETICS OF FREE RADICALS DE-FG05-85ER13439 1-AUG-1985 to 31-JUL-1994 Robert F. Curl and Graham P. Glass Principal Investigators Introduction This research was directed at the detection, monitoring, and study (by infrared absorption spectroscopy) of the chemical kinetic behavior of small free radical species thought to be important intermediates in combustion. The work typically progressed from the detection and analysis of the infrared spectrum of combustion radical to the utilization of the infrared spectrum thus obtained in the investigation of chemical kinetics of the radical species. The methodology employed was infrared kinetic spectroscopy. In this technique the radical is produced by UV flash photolysis using an excimer laser and then

254

Optical and plasmonic spectroscopy with cantilever shaped materials  

NLE Websites -- All DOE Office Websites (Extended Search)

plasmonic spectroscopy with cantilever shaped materials plasmonic spectroscopy with cantilever shaped materials This article has been downloaded from IOPscience. Please scroll down to see the full text article. 2011 J. Phys. D: Appl. Phys. 44 445102 (http://iopscience.iop.org/0022-3727/44/44/445102) Download details: IP Address: 128.219.49.13 The article was downloaded on 28/12/2012 at 18:01 Please note that terms and conditions apply. View the table of contents for this issue, or go to the journal homepage for more Home Search Collections Journals About Contact us My IOPscience IOP PUBLISHING JOURNAL OF PHYSICS D: APPLIED PHYSICS J. Phys. D: Appl. Phys. 44 (2011) 445102 (9pp) doi:10.1088/0022-3727/44/44/445102 Optical and plasmonic spectroscopy with cantilever shaped materials L Tetard 1 , A Passian 1,2 , R H Farahi 1 , B H Davison 1 , A L Lereu 3 and T Thundat

255

2010 GRC VIBRATIONAL SPECTROSCOPY AUGUST 1 - AUGUST 6, 2010  

SciTech Connect

The Vibrational Spectroscopy conference focuses on using vibrational spectroscopy to probe structure and dynamics of molecules in gases, liquids, and at interfaces. The conference explores the wide range of state-of-the-art techniques based on vibrational motion. These techniques span the fields of time-domain, high-resolution frequency-domain, spatially-resolved, nonlinear and multidimensional spectroscopies. The conference highlights the application of these techniques in chemistry, materials, biology, and medicine. The theory of molecular vibrational motion and its connection to spectroscopic signatures and chemical reaction dynamics is the third major theme of the meeting. The goal is to bring together a collection of researchers who share common interests and who will gain from discussing work at the forefront of several connected areas. The intent is to emphasize the insights and understanding that studies of vibrations provide about a variety of molecular systems ranging from small polyatomic molecules to large biomolecules and nanomaterials.

Brooks Pate

2010-08-06T23:59:59.000Z

256

Charm and Charmonium Spectroscopy at B-factories  

SciTech Connect

Since a few years, charm and charmonium spectroscopy has revived, both from experimental and theoretical point of views. Many new states have been discovered triggering numerous theoretical publications. The B-factories with their large enriched charm sample have played a leading role on the experimental side with the observation and study of most of the new states. Other experiments such as CLEO and CDF have also contributed. Classical hadron spectroscopy predicted some of these new states, but not all of them. Therefore a lot of effort have been spent in order to understand the nature of the later. We are summarizing here the most recent and important results in hadron spectroscopy, including strange-charm mesons, charm baryons and charmonium and charmonium-like states.

Grenier, Philippe; /SLAC /Ecole Normale Superieure, CNRS

2007-05-18T23:59:59.000Z

257

Photon Sciences | Beamlines | SRX: Submicron Resolution X-ray Spectroscopy  

NLE Websites -- All DOE Office Websites (Extended Search)

SRX: Submicron Resolution X-ray Spectroscopy SRX: Submicron Resolution X-ray Spectroscopy Poster | Fact Sheet | Preliminary Design Report Scientific Scope Scientific communities such as environmental sciences, life sciences, and material sciences have identified the need to develop analytical resources to advance the understanding of complex natural and engineered systems that are heterogeneous on the micron to nanometer scale. These needs for high intensity x-ray nanoprobes resulted in the commitment of the NSLS-II Project to build the Submicron Resolution X-ray (SRX) Spectroscopy beamline showing a unique combination of high spectral resolution over a very broad energy range and very high beam intensity in a sub-micrometer spot. NSLS-II will provide one of the best sources in the world for such an instrument.

258

2-2 Environmental Spectroscopy & Biogeochemistry Facility  

NLE Websites -- All DOE Office Websites (Extended Search)

ES&B Overview ES&B Overview Environmental Spectroscopy & Biogeochemistry Facility The Environmental Spectroscopy & Biogeochemistry (ES&B) Facility focuses on environ- mental molecular science and application of the fundamental concepts of physical chemistry to the study of chemical reactions in heterogeneous natural materials, with an emphasis on soil and subsurface systems. The ES&B Facility staff, along with other Pacific Northwest National Laboratory (PNNL) staff, form a multidisciplinary organization with expertise in chemistry, mineral physics, geochemistry, soil chemistry, microbiology, hydrology, and environmental engineering. Capabilities are available for materials characterization, aqueous-phase and solid-phase speciation and reaction/kinetic measurements, analytical environmental chemistry, molecular

259

Photocapacitance spectroscopy of surface states on indium phosphide photoelectrodes  

SciTech Connect

Indium phosphide photoelectrodes have been studied in situ using electrochemical photocapacitance spectroscopy. The observed photocapacitance spectra were a strong function of electrode surface conditions. The photoionization energies of the chemically induced surface states correlated well with previously reported values determined by surface photovoltage spectroscopy. The chemical treatment of the InP electrode surface with Co and Pt reduced the concentration of deep level interface states near the valence band and introduced a new state at E/sub v/+1.2 eV.

Goodman, C.E.; Wessels, B.W.; Ang, P.G.P.

1984-08-15T23:59:59.000Z

260

Excited State Spectroscopy in the Lattice Gross-Neveu Model  

E-Print Network (OSTI)

We present preliminary results of an excited state spectroscopy calculation in the 2-d lattice Gross-Neveu model. We address the construction of suitable interpolators for the variational method and their overlap with excitations. We comment on the role of the eigenvectors as a tool for matching scattering states on lattices with different volumes.

Julia Danzer; Christof Gattringer

2007-10-09T23:59:59.000Z

Note: This page contains sample records for the topic "angle-resolved photoemission spectroscopy" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


261

Novel gold cantilever for nano-Raman spectroscopy of graphene  

Science Conference Proceedings (OSTI)

This paper presents the simultaneous topographical and tip-enhanced Raman imaging of single layer and multilayer graphene flakes. The probe tips suitable for tapping mode atomic force microscopy (AFM) and tip-enhanced Raman spectroscopy have been fabricated ... Keywords: Atomic force microscopy, Graphene, Nano-Raman, Tip-enhanced

Valentinas Snitka; Raul D. Rodrigues; Vitas Lendraitis

2011-08-01T23:59:59.000Z

262

Positron annihilation spectroscopy study of materials for reactor vessels  

Science Conference Proceedings (OSTI)

Steels used in the nuclear industry have been experimentally studied by positron annihilation spectroscopy. Analysis of the experimental results and their comparison with the existing data make it possible to reveal vacancy defects, in particular, those caused by neutron radiation, and to determine their size.

Grafutin, V. I.; Prokop'ev, E. P. [Institute for Theoretical and Experimental Physics (Russian Federation); Krsjak, V.; Burcl, R.; Haehner, P.; Zeman, A. [Joint Research Centre of the European Commission, Institute for Energy (Netherlands); Ilyukhina, O. V., E-mail: ilyukhina@itep.ru [Institute for Theoretical and Experimental Physics (Russian Federation); Erak, D. [Russian Research Centre Kurchatov Institute (Russian Federation); Mogilevskyi, M. A.; Myasischeva, G. G.; Funtikov, Yu. V. [Institute for Theoretical and Experimental Physics (Russian Federation)

2011-02-15T23:59:59.000Z

263

Development of Raman Spectroscopy for a Steam Generator Heated Crevice  

Science Conference Proceedings (OSTI)

The crevice formed by the tube / tube support plate (tube/TSP) intersection in a pressurized water reactor (PWR) steam generator (SG) is a concentration site for nonvolatile impurities from steam generator water (referred to as hideout). This report describes development of a Raman spectroscopy device to investigate this chemical concentration process in situ in a simulated heated crevice.

2003-11-11T23:59:59.000Z

264

Single atom identification by energy dispersive x-ray spectroscopy  

SciTech Connect

Using aberration-corrected scanning transmission electron microscope and energy dispersive x-ray spectroscopy, single, isolated impurity atoms of silicon and platinum in monolayer and multilayer graphene are identified. Simultaneously acquired electron energy loss spectra confirm the elemental identification. Contamination difficulties are overcome by employing near-UHV sample conditions. Signal intensities agree within a factor of two with standardless estimates.

Lovejoy, T. C.; Dellby, N.; Krivanek, O. L. [Nion, 1102 8th St., Kirkland, Washington 98033 (United States); Ramasse, Q. M. [SuperSTEM Laboratory, STFC Daresbury, Keckwick Lane, Daresbury WA4 4AD (United Kingdom); Falke, M.; Kaeppel, A.; Terborg, R. [Bruker Nano GmbH, Schwarzschildstr. 12, 12489 Berlin (Germany); Zan, R. [School of Physics and Astronomy, University of Manchester, Manchester M13 9PL (United Kingdom)

2012-04-09T23:59:59.000Z

265

Synchrotron Radiation Photoemission Spectroscopic Study of Band Offsets and Interface Self-cleaning by Atomic Layer Deposited HfO2 on In0.53Ga0.47As and In0.52Al0.48As  

SciTech Connect

The Synchrotron Radiation Photoemission Spectroscopic (SRPES) study was conducted to (a) investigate the surface chemistry of In{sub 0.53}Ga{sub 0.47}As and In{sub 0.52}Al{sub 0.48}As post chemical and thermal treatments, (b) construct band diagram and (c) investigate the interface property of HfO{sub 2}/In{sub 0.53}Ga{sub 0.47}As and HfO{sub 2}/In{sub 0.52}Al{sub 0.48}As. Dilute HCl and HF etch remove native oxides on In{sub 0.53}Ga{sub 0.47}As and In{sub 0.52}Al{sub 0.47}As, whereas in-situ vacuum annealing removes surface arsenic pile-up. After the atomic layer deposition of HfO{sub 2}, native oxides were considerably reduced compared to that in as-received epi-layers, strongly suggesting the self-clean mechanism. Valence and conduction band offsets are measured to be 3.37 {+-} 0.1eV, 1.80 {+-} 0.3eV for In{sub 0.53}Ga{sub 0.47}As and 3.00 {+-} 0.1eV, 1.47 {+-} 0.3eV for In{sub 0.52}Al{sub 0.47}As, respectively.

Kobayashi, Masaharu; /SLAC, SSRL; Chen, P.T.; Sun, Y.; Goel, N.; Majhi, P.; Garner, M; Tsai, W.; Pianetta, P.; Nishi, Y.; /SLAC, SSRL

2008-10-31T23:59:59.000Z

266

Geophysical applications of nuclear resonant spectroscopy Wolfgang Sturhahn and Jennifer M. Jackson*  

E-Print Network (OSTI)

Geophysical applications of nuclear resonant spectroscopy Wolfgang Sturhahn and Jennifer M. Jackson summarize recent developments of nuclear resonant spectroscopy methods like nuclear resonant inelastic x important information on valence, spin state, and magnetic ordering. Both methods use a nuclear resonant

Jackson, Jennifer M.

267

Standoff Detection of Chemicals Using Rydberg Fingerprint Spectroscopy and Microwave Rayleigh Scattering  

The invention relates to a method for standoff trace chemical sensing. The basis forthe technique is Rydberg Fingerprint Spectroscopy followed by microwave-baseddetection.In Rydberg Fingerprint Spectroscopy, target molecules are first excited to ...

268

Development of multimodal spectroscopy for the detection of vulnerable atherosclerotic plaques  

E-Print Network (OSTI)

The combination of reflectance, fluorescence, and Raman spectroscopy - which is termed multimodal spectroscopy (MMS) - provides complementary and depth-sensitive information about tissue composition. As such, MMS can provide ...

Š?epanovi?, Obrad R., 1980-

2008-01-01T23:59:59.000Z

269

High-resolution NMR spectroscopy of biological tissues using projected Magic Angle Spinning  

E-Print Network (OSTI)

High-resolution NMR spectroscopy of biological tissues using486-5744 pines@berkeley.edu NMR spectroscopy of biologicalAbstract: High-resolution NMR spectra of materials subject

Martin, Rachel W.; Jachmann, Rebecca C.; Sakellariou, Dimitris; Nielsen, Ulla Gro; Pines, Alexander

2005-01-01T23:59:59.000Z

270

Dirac Charge Dynamcs in Graphene by Infrared Spectroscopy  

NLE Websites -- All DOE Office Websites (Extended Search)

Dirac Charge Dynamcs in Graphene by Infrared Spectroscopy Print Dirac Charge Dynamcs in Graphene by Infrared Spectroscopy Print Graphene-a single layer of carbon atoms arranged in a honeycomb lattice-has very high conductivity that can be tuned by applying a gate voltage. The charge carriers in graphene can travel ballistically over great distances (~1 micron) without scattering. These unusual electronic properties make graphene a promising candidate for future nanoelectronics. Using infrared spectromicroscopy at ALS Beamline 1.4, a group of researchers from the University of California at San Diego, Columbia University, and the ALS has succeeded in probing the dynamical properties of the charge carriers in graphene with an accuracy never before achieved. Their results have uncovered signatures of many-body interactions in graphene and have demonstrated the potential of graphene for novel applications in optoelectronics.

271

Microsoft PowerPoint - SpectroscopyTechniques_EXAFS  

NLE Websites -- All DOE Office Websites (Extended Search)

X-ray Absorption Fine Structure Spectroscopy (EXAFS) X-ray Absorption Fine Structure Spectroscopy (EXAFS) * Provides details on how x rays are absorbed by an atom at energies near X18A,B,X19A * Provides details on how x-rays are absorbed by an atom at energies near and above the core-level binding energies of that atom * Gives the modulation of an atom's x-ray absorption probability due to the chemical and physical state of the atom * Especially sensitive to the formal oxidation state, coordination chemistry, and the distances, coordination numbers, and species of the atoms immediately surrounding the selected element * Provides a practical, and relatively simple, way to determine the chemical state and local atomic structure for a selected atomic species

272

Dirac Charge Dynamcs in Graphene by Infrared Spectroscopy  

NLE Websites -- All DOE Office Websites (Extended Search)

Dirac Charge Dynamcs in Graphene by Infrared Spectroscopy Print Dirac Charge Dynamcs in Graphene by Infrared Spectroscopy Print Graphene-a single layer of carbon atoms arranged in a honeycomb lattice-has very high conductivity that can be tuned by applying a gate voltage. The charge carriers in graphene can travel ballistically over great distances (~1 micron) without scattering. These unusual electronic properties make graphene a promising candidate for future nanoelectronics. Using infrared spectromicroscopy at ALS Beamline 1.4, a group of researchers from the University of California at San Diego, Columbia University, and the ALS has succeeded in probing the dynamical properties of the charge carriers in graphene with an accuracy never before achieved. Their results have uncovered signatures of many-body interactions in graphene and have demonstrated the potential of graphene for novel applications in optoelectronics.

273

Impedance spectroscopy of electrodes modified by Langmuir-Blodgett films  

SciTech Connect

The techniques of a.c. impedance spectroscopy and FTIR spectroscopy are used to investigate the properties of Langmuir-Blodgett (LB) films deposited respectively on ITO (Indium Tin Oxyde) coated glass electrode, and on Calcium Fluoride plates. 22-tricosenoic acid is transferred from a subphase containing an electrolyte and a redox system (Fe(CN){sup 3{minus}/4{minus}}). The IR spectra show selective insertion of the Fe(CN){sup 4{minus}} ion in the film. Measurements of the complex impedance of 22-tricosenoic acid are then presented and discussed as a function of the number of deposited layers. An equivalent electrical circuit is proposed which takes into account the defects of the film. {copyright} {ital 1996 American Institute of Physics.}

Vignau, L.; Morand, J.P. [Laboratoire de Photophysique-Photochimie Moleculaire (France); Frimigacci, M. [Ecole Nationale Superieure de Chimie et de Physique de Bordeaux, Universite de Bordeaux I, 33405 Talence Cedex (France)

1996-01-01T23:59:59.000Z

274

Time-frequency resolved ultrafast spectroscopy techniques using wavelet analysis  

E-Print Network (OSTI)

New experimental techniques based on non-linear ultrafast spectroscopies have been developed over the last few years, and have been demonstrated to provide powerful probes of quantum dynamics in different types of molecular aggregates, including both natural and artificial light harvesting complexes. Fourier transform-based spectroscopies have been particularly successful, yet 'complete' spectral information normally necessitates the loss of all information on the temporal sequence of events in a signal. This information though is particularly important in transient or multi-stage processes, in which the spectral decomposition of the data evolves in time. By going through several examples of ultrafast quantum dynamics, we demonstrate that the use of wavelets provide an efficient and accurate way to simultaneously acquire both temporal and frequency information about a signal, and argue that this greatly aids the elucidation and interpretation of physical process responsible for non-stationary spectroscopic features, such as those encountered in coherent excitonic energy transport.

Javier Prior; Enrique Castro; Alex W. Chin; Javier Almeida; Susana F. Huelga; Martin B. Plenio

2013-08-21T23:59:59.000Z

275

Exploitation of resonance Raman spectroscopy as a remote chemical sensor  

SciTech Connect

We have discussed recent experimental results using a resonance-Raman-based LIDAR system as a remote chemical sensor. This spectroscopy has the fundamental advantage that it is based on optical fingerprints that are insensitive to environmental perturbations. By taking advantage of resonance enhancement, which 6 orders-of-magnitude, can be as large as 4 to an increased sensing range for a given chemical concentration or lower detection limit for a given stand-off distance can be realized. The success discussed above can in part be traced back to the use of new state-of-the-art technologies which, only recently, have allowed the phenomenon of resonance-enhanced Raman spectroscopy to be fully exploited as a remote chemical sensor platform. Since many chemicals have electronic transitions in the UV/IS, it is expected that many will have pronounced resonance enhancements.

Sedlacek, A.J.; Chen, C.L.

1995-08-01T23:59:59.000Z

276

Photodissociation dynamics and spectroscopy of free radical combustion intermediates  

Science Conference Proceedings (OSTI)

The photodissociation spectroscopy and dynamics of free radicals is studied by the technique of fast beam photofragment translational spectroscopy. Photodetachment of internally cold, mass-selected negative ions produces a clean source of radicals, which are subsequently dissociated and detected. The photofragment yield as a function of photon energy is obtained, mapping out the dissociative and predissociative electronic states of the radical. In addition, the photodissociation dynamics, product branching ratios, and bond energies are probed at fixed photon energies by measuring the translational energy, P(E{sub T}), and angular distribution of the recoiling fragments using a time- and position-sensitive detector. Ab initio calculations are combined with dynamical and statistical models to interpret the observed data. The photodissociation of three prototypical hydrocarbon combustion intermediates forms the core of this work.

Osborn, D.L.

1996-12-01T23:59:59.000Z

277

Raman/FTIR spectroscopy of oil shale retort gases  

DOE Green Energy (OSTI)

A Raman facility was assembled in order to aid in the evaluation of the feasibility of using Raman or FTIR spectroscopy for analyzing gas mixtures of interest in oil shale. Applications considered in oil shale research included both retort monitoring and laboratory kinetic studies. Both techniques gave limits of detection between 10 and 1000 ppM for ten representative pertinent gases. Both techniques are inferior as a general analytical technique for oil shale gas analysis in comparison with mass spectroscopy, which had detection limits between 1 and 50 ppM for the same gases. The conclusion of the feasibility study was to recommend that mass spectroscopic techniques be used for analyzing gases of interest to oil shale.

Richardson, J.H.; Monaco, S.B.; Sanborn, R.H.; Hirschfeld, T.B.; Taylor, J.R.

1982-08-01T23:59:59.000Z

278

Method and apparatus for two-dimensional spectroscopy  

SciTech Connect

Preferred embodiments of the invention provide for methods and systems of 2D spectroscopy using ultrafast, first light and second light beams and a CCD array detector. A cylindrically-focused second light beam interrogates a target that is optically interactive with a frequency-dispersed excitation (first light) pulse, whereupon the second light beam is frequency-dispersed at right angle orientation to its line of focus, so that the horizontal dimension encodes the spatial location of the second light pulse and the first light frequency, while the vertical dimension encodes the second light frequency. Differential spectra of the first and second light pulses result in a 2D frequency-frequency surface equivalent to double-resonance spectroscopy. Because the first light frequency is spatially encoded in the sample, an entire surface can be acquired in a single interaction of the first and second light pulses.

DeCamp, Matthew F. (Swarthmore, PA); Tokmakoff, Andrei (Lexington, MA)

2010-10-12T23:59:59.000Z

279

Cone penetrometer fiber optic raman spectroscopy probe assembly  

DOE Patents (OSTI)

A chemically and mechanically robust optical Raman spectroscopy probe assembly that can be incorporated in a cone penetrometer (CPT) for subsurface deployment. This assembly consists of an optical Raman probe and a penetrometer compatible optical probe housing. The probe is intended for in-situ chemical analysis of chemical constituents in the surrounding environment. The probe is optically linked via fiber optics to the light source and the detection system at the surface. A built-in broadband light source provides a strobe method for direct measurement of sample optical density. A mechanically stable sapphire window is sealed directly into the side-wall of the housing using a metallic, chemically resistant, hermetic seal design. This window permits transmission of the interrogation light beam and the resultant signal. The spectroscopy probe assembly is capable of accepting Raman, Laser induced Fluorescence, reflectance, and other optical probes with collimated output for CPT deployment.

Kyle, Kevin R. (Brentwood, CA); Brown, Steven B. (Livermore, CA)

2000-01-01T23:59:59.000Z

280

Free-Electron Laser-Powered Electron Paramagnetic Resonance Spectroscopy  

E-Print Network (OSTI)

Electron paramagnetic resonance (EPR) spectroscopy interrogates unpaired electron spins in solids and liquids to reveal local structure and dynamics; for example, EPR has elucidated parts of the structure of protein complexes that have resisted all other techniques in structural biology. EPR can also probe the interplay of light and electricity in organic solar cells and light-emitting diodes, and the origin of decoherence in condensed matter, which is of fundamental importance to the development of quantum information processors. Like nuclear magnetic resonance (NMR), EPR spectroscopy becomes more powerful at high magnetic fields and frequencies, and with excitation by coherent pulses rather than continuous waves. However, the difficulty of generating sequences of powerful pulses at frequencies above 100 GHz has, until now, confined high-power pulsed EPR to magnetic fields of 3.5 T and below. Here we demonstrate that ~1 kW pulses from a free-electron laser (FEL) can power a pulsed EPR spectrometer at 240 GHz...

Takahashi, S; Edwards, D T; van Tol, J; Ramian, G; Han, S; Sherwin, M S

2012-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "angle-resolved photoemission spectroscopy" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


281

Photodissociation spectroscopy and dynamics of free radicals, clusters, and ions  

Science Conference Proceedings (OSTI)

The photodissociation spectroscopy and dynamics of free radicals and ions is studied to characterize the dissociative electronic states in these species. To accomplish this, a special method of radical production, based on the photodetachment of the corresponding negative ion, has been combined with the technique of fast beam photofragment translational spectroscopy. The photofragment yield as a function of photon energy is obtained, mapping out the dissociative and predissociative electronic states. Branching ratios to various product channels, the translational energy distributions of the fragments, and bond dissociation energies are then determined at selected photon energies. The detailed picture of photodissociation dynamics is provided with the aid of ab initio calculations and a statistical model to interpret the observed data. Important reaction intermediates in combustion reactions have been studied: CCO, C{sub 2}H{sub 5}O, and linear C{sub n} (n = 4--6).

Hyeon, Choi

1999-12-16T23:59:59.000Z

282

Dirac Charge Dynamcs in Graphene by Infrared Spectroscopy  

NLE Websites -- All DOE Office Websites (Extended Search)

Dirac Charge Dynamcs in Graphene Dirac Charge Dynamcs in Graphene by Infrared Spectroscopy Dirac Charge Dynamcs in Graphene by Infrared Spectroscopy Print Wednesday, 29 October 2008 00:00 Graphene-a single layer of carbon atoms arranged in a honeycomb lattice-has very high conductivity that can be tuned by applying a gate voltage. The charge carriers in graphene can travel ballistically over great distances (~1 micron) without scattering. These unusual electronic properties make graphene a promising candidate for future nanoelectronics. Using infrared spectromicroscopy at ALS Beamline 1.4, a group of researchers from the University of California at San Diego, Columbia University, and the ALS has succeeded in probing the dynamical properties of the charge carriers in graphene with an accuracy never before achieved. Their results have uncovered signatures of many-body interactions in graphene and have demonstrated the potential of graphene for novel applications in optoelectronics.

283

Supplemental Report: Application of Emission Spectroscopy to Monitoring Technetium  

Science Conference Proceedings (OSTI)

This report provides supplemental information to an earlier report BNF-98-003-0199, ''Evaluation of Emission Spectroscopy for the On-Line Analysis of Technetium''. In this report data is included from real Hanford samples as well as for solutions spiked with technetium. This supplemental work confirms the ability of ICP-ES to monitor technetium as it breaks through an ion exchange process.

Spencer, W.A.

2000-07-27T23:59:59.000Z

284

Measuring of exhaust gas emissions using absorption spectroscopy  

Science Conference Proceedings (OSTI)

This paper describes an optical fibre sensor for the detection of NOx (NO2 and NO) and CO2 in the exhaust system of a road vehicle. The measurement is based on a free path interaction zone which is interrogated using ... Keywords: absorption spectroscopy, air pollution, carbon dioxide, emissions measurement, exhaust gas emissions, gas sensors, infrared, nitrogen dioxide, nitrogen oxide, optical fibre sensors, ultraviolet, vehicle emissions

Eamonn Hawe; Gerard Dooly; Colin Fitzpatrick; Paul Chambers; Elfed Lewis; W. Z. Zhao; T. Sun; K. T. V. Grattan; M. Degner; H. Ewald; S. Lochmann; G. Bramman; C. Wei; D. Hitchen; J. Lucas; A. Al-Shamma'a; E. Merlone-Borla; P. Faraldi; M. Pidria

2008-02-01T23:59:59.000Z

285

Advances in Optical Spectroscopy and Imaging of Breast Lesions  

SciTech Connect

A review is presented of recent advances in optical imaging and spectroscopy and the use of light for addressing breast cancer issues. Spectroscopic techniques offer the means to characterize tissue components and obtain functional information in real time. Three-dimensional optical imaging of the breast using various illumination and signal collection schemes in combination with image reconstruction algorithms may provide a new tool for cancer detection and monitoring of treatment.

Demos, S; Vogel, A J; Gandjbakhche, A H

2006-01-03T23:59:59.000Z

286

Laser produced plasma diagnostics by cavity ringdown spectroscopy and applications  

SciTech Connect

Laser-produced plasmas have many applications for which detailed characterization of the plume is requested. Cavity ring-down spectroscopy is a versatile absorption method which provides data on the plume and its surroundings, with spatial and temporal resolution. The measured absorption line shapes contain information about angular and velocity distributions within the plume. In various plasmas we have observed molecules or metastable atoms which were not present in the emission spectra.

Milosevic, S. [Institute of Physics, Zagreb (Croatia)

2012-05-25T23:59:59.000Z

287

Spectroscopy of a Qubit Array via a Single Transmission Line  

E-Print Network (OSTI)

Frequency-selective readout for superconducting qubits opens the way towards scaling qubit circuits up without increasing the number of measurement lines. Here we demonstrate the readout of an array of 7 flux qubits located on the same chip. Each qubit is placed near an individual lambda/4 resonator which, in turn, is coupled to a common microwave transmission line. We performed spectroscopy of all qubits and determined their parameters in a single measurement run.

Jerger, M; Macha, P; Huebner, U; Lukashenko, A; Il'ichev, E; Ustinov, A V

2011-01-01T23:59:59.000Z

288

Nonlinearity sensing via photon-statistics excitation spectroscopy  

SciTech Connect

We propose photon-statistics excitation spectroscopy as an adequate tool to describe the optical response of a nonlinear system. To this end we suggest to use optical excitation with varying photon statistics as another spectroscopic degree of freedom to gather information about the system in question. The responses of several simple model systems to excitation beams with different photon statistics are discussed. Possible spectroscopic applications in terms of identifying lasing operation are pointed out.

Assmann, Marc; Bayer, Manfred [Experimentelle Physik 2, Technische Universitaet Dortmund, D-44221 Dortmund (Germany)

2011-11-15T23:59:59.000Z

289

Rapid Compositional Analysis of Microalgae by NIR Spectroscopy  

DOE Green Energy (OSTI)

One of the challenges associated with the development of algal biofuels is the rapid determination of the composition of algae. The oil content in particular is important in a biofuels production process and selecting the right algal strain from a pool of potentially thousands of candidates remains difficult. This article discusses how near infrared (NIR) spectroscopy is a technology that could be used for distinguishing algal strains and more importantly, differentiating between high and low oil content of biomass.

Laurens, L. M. L.; Wolfrum, E. J.

2012-03-01T23:59:59.000Z

290

Application of photothermal deflection spectroscopy to electrochemical interfaces  

DOE Green Energy (OSTI)

This dissertation discusses the theory and practice of Photothermal Deflection Spectroscopy (PDS, which is also known as probe beam deflection spectroscopy, PBDS, probe deflection technique, and mirage effect spectroscopy) with respect to electrochemical systems. Much of the discussion is also relevant to non-electrochemical systems. PDS can measure the optical absorption spectrum of interfaces and concentration gradients in the electrolyte adjacent to the electrode. These measurements can be made on a wide variety of electrode surfaces and can be performed under dynamic conditions. The first three chapters discuss the theory of the phenomena that can be detected by PDS, and the equipment used in a PDS system. A secondary gradient technique'' is proposed, which places the probe beam on the back of an electrode. The results of a numerical model yield a method for determining the offset of the probe beam from the electrode surface based on the frequency response of the PDS signal. The origin and control of noise in the PDS signal are discussed. A majority of the signal noise appears to be acoustic in origin. The electrochemical oxidation of platinum is used to demonstrate that PDS has sub-monolayer sensitivity necessary to study interfacial chemistry. The results allow us to propose a two-reaction oxidation mechanism: the platinum is electrochemically oxidized to form platinum dihydroxide and dehydrated by a non-electrochemical second-order reaction. The final chapter discusses the relation of PDS to similar and competing techniques, and considers possibilities for the future of the technique.

Rudnicki, J.D.; McLarnon, F.R.; Cairns, E.J.

1992-03-01T23:59:59.000Z

291

Application of photothermal deflection spectroscopy to electrochemical interfaces  

DOE Green Energy (OSTI)

This dissertation discusses the theory and practice of Photothermal Deflection Spectroscopy (PDS, which is also known as probe beam deflection spectroscopy, PBDS, probe deflection technique, and mirage effect spectroscopy) with respect to electrochemical systems. Much of the discussion is also relevant to non-electrochemical systems. PDS can measure the optical absorption spectrum of interfaces and concentration gradients in the electrolyte adjacent to the electrode. These measurements can be made on a wide variety of electrode surfaces and can be performed under dynamic conditions. The first three chapters discuss the theory of the phenomena that can be detected by PDS, and the equipment used in a PDS system. A ``secondary gradient technique`` is proposed, which places the probe beam on the back of an electrode. The results of a numerical model yield a method for determining the offset of the probe beam from the electrode surface based on the frequency response of the PDS signal. The origin and control of noise in the PDS signal are discussed. A majority of the signal noise appears to be acoustic in origin. The electrochemical oxidation of platinum is used to demonstrate that PDS has sub-monolayer sensitivity necessary to study interfacial chemistry. The results allow us to propose a two-reaction oxidation mechanism: the platinum is electrochemically oxidized to form platinum dihydroxide and dehydrated by a non-electrochemical second-order reaction. The final chapter discusses the relation of PDS to similar and competing techniques, and considers possibilities for the future of the technique.

Rudnicki, J.D.; McLarnon, F.R.; Cairns, E.J.

1992-03-01T23:59:59.000Z

292

Raman spectroscopy on simple molecular systems at very high density  

DOE Green Energy (OSTI)

We present an overview of how Raman spectroscopy is done on simple molecular substances at high pressures. Raman spectroscopy is one of the most powerful tools for studying these substances. It is often the quickest means to explore changes in crystal and molecular structures, changes in bond strength, and the formation of new chemical species. Raman measurements have been made at pressures up to 200 GPa (2 Mbar). Even more astonishing is the range of temperatures (4-5200/degree/K) achieved in various static and dynamic (shock-wave) pressure experiments. One point we particularly wish to emphasize is the need for a good theoretical understanding to properly interpret and use experimental results. This is particularly true at ultra-high pressures, where strong crystal field effects can be misinterpreted as incipient insulator-metal transitions. We have tried to point out apparatus, techniques, and results that we feel are particularly noteworthy. We have also included some of the /open quotes/oral tradition/close quotes/ of high pressure Raman spectroscopy -- useful little things that rarely or never appear in print. Because this field is rapidly expanding, we discuss a number of exciting new techniques that have been informally communicated to us, especially those that seem to open new possibilities. 58 refs., 18 figs.

Schiferl, D.; LeSar, R.S.; Moore, D.S.

1988-01-01T23:59:59.000Z

293

Infrared spectroscopy and hydrogen isotope geochemistry of hydrous silicate glasses  

DOE Green Energy (OSTI)

The focus of this project is the combined appication of infrared spectroscopy and stable isotope geochemistry to the study of hydrogen-bearing species dissolved in silicate melts and glasses. We are conducting laboratory experiments aimed at determining the fractionation of D and H between melt species (OH and H{sub 2}O) and hydrous vapor and the diffusivities of these species in glasses and melts. Knowledge of these parameters is critical to understanding the behavior of hydrogen isotopes during igneous processes and hydrothermal processes. These results also could be valuable in application of glass technology to development of nuclear waste disposal strategies.

Epstein, S.; Stolper, E.

1992-01-01T23:59:59.000Z

294

8th international conference on electronic spectroscopy and structure  

SciTech Connect

Gathering from 33 countries around the world, 408 registrants and a number of local drop-in participants descended on the Clark Kerr Campus of the University of California, Berkeley, from Monday, August 7 through Saturday, August 12, 2000 for the Eighth International Conference on Electronic Structure and Spectroscopy (ICESS8). At the conference, participants benefited from an extensive scientific program comprising more than 100 oral presentations (plenary lectures and invited and contributed talks) and 330 poster presentations, as well as ample time for socializing and a tour of the Advanced Light Source (ALS) at the nearby Lawrence Berkeley National Laboratory.

Robinson, Art

2000-10-16T23:59:59.000Z

295

Position-Sensitive Nuclear Spectroscopy with Pixel Detectors  

SciTech Connect

State-of-the-art hybrid semiconductor pixel detectors such as Medipix2 are suitable for energy- and position-sensitive nuclear spectroscopy. In addition to excellent energy- and spatial-resolution, these devices can operate in spectroscopic, single-quantum counting and/or on-line tracking mode. A devoted compact USB-readout interface provides functionality and ease of operation. The compact and versatile Medipix2/USB radiation camera provides visualization, vacuum and room-temperature operation as a real-time portable active nuclear emulsion.

Granja, Carlos; Vykydal, Zdenek; Jakubek, Jan; Pospisil, Stanislav [Institute of Experimental and Applied Physics, Czech Technical University in Prague Horska 3a/22, 12800 Prague 2 (Czech Republic)

2007-10-26T23:59:59.000Z

296

Application of Raman spectroscopy to high-temperature analytical measurements  

Science Conference Proceedings (OSTI)

There are numerous analytical applications of scatter-emission and/or absorption spectroscopy applied to liquids and solids at 0 to 350 C. This paper describes an all-silica fiberoptic probe which is useful for spectral analyses from 0 to 1600 K and can be used in harsh chemical environments. The probe has been used for Raman spectral analyses of many molten salt and solid material systems to 1000 C. It has applications for such studies at higher temperature ranges. The instrumentation required along with the demonstrated and proposed applications of the all-silica probe are presented and discussed.

Young, J.P.; Dai, S.; Lee, Y.; Xizo, H.

1997-01-01T23:59:59.000Z

297

Near-infrared spectroscopy. Innovative technology summary report  

Science Conference Proceedings (OSTI)

A near-infrared (NIR) spectroscopy system with a remote fiber-optic probe was developed and demonstrated to measure the water content of high-level radioactive wastes from the underground storage tanks at the Hanford Site in richland Washington. The technology was developed as a cost-effective and safer alternative to the thermogravimetric analysis (TGA) technique in use as the baseline. This work was supported by the Tanks Focus Area (TFA) within the Department of Energy`s (DOE) Office of Science and Technology (OST) in cooperation with the Hanford Tank Waste Remediation System (TWRS) Program.

Not Available

1999-07-01T23:59:59.000Z

298

Holdup Measures on an SRNL Mossbauer Spectroscopy Instrument  

SciTech Connect

Gamma-ray holdup measurements of a Mossbauer spectroscopy instrument are described and modeled. In the qualitative acquisitions obtained in a low background area of Savannah River National Laboratory, only Am-241 and Np-237 activity were observed. The Am-241 was known to be the instrumental activation source, while the Np-237 is clearly observed as a source of contamination internal to the instrument. The two sources of activity are modeled separately in two acquisition configurations using two separate modeling tools. The results agree well, demonstrating a content of (1980 {+-} 150) {mu}Ci Am-241 and (110 {+-} 50) {mu}Ci of Np-237.

Dewberry, R.; Brown, T.; Salaymeh, S.

2010-05-05T23:59:59.000Z

299

Band Structure Asymmetry of Bilayer Graphene Revealed by Infrared Spectroscopy  

Science Conference Proceedings (OSTI)

We report on infrared spectroscopy of bilayer graphene integrated in gated structures. We observe a significant asymmetry in the optical conductivity upon electrostatic doping of electrons and holes. We show that this finding arises from a marked asymmetry between the valence and conduction bands, which is mainly due to the inequivalence of the two sublattices within the graphene layer and the next-nearest-neighbor interlayer coupling. From the conductivity data, the energy difference of the two sublattices and the interlayer coupling energy are directly determined.

Li, Z.Q.; Henriksen, E.A.; Jiang, Z.; Hao, Zhao; Martin, Michael C.; Kim, P.; Stormer, H.L.; Basov, Dimitri N.

2008-12-10T23:59:59.000Z

300

Excited-Nucleon Spectroscopy with 2+1 Fermion Flavors  

E-Print Network (OSTI)

We present progress made by the Hadron Spectrum Collaboration (HSC) in determining the tower of excited nucleon states using 2+1-flavor anisotropic clover lattices. The HSC has been investigating interpolating operators projected into irreducible representations of the cubic group in order to better calculate two-point correlators for nucleon spectroscopy; results are published for quenched and 2-flavor anisotropic Wilson lattices. In this work, we present the latest results using a new technique, distillation, which allows us to reach higher statistics than before. Future directions will be outlined at the end.

Saul Cohen; John M. Bulava; Justin Foley; Colin Morningstar; Ricky Wong; Robert G. Edwards; Balint Joo; David G. Richards; K. Jimmy Juge; Huey-Wen Lin; Nilmani Mathur; Michael J. Peardon; Sinead M. Ryan

2009-11-17T23:59:59.000Z

Note: This page contains sample records for the topic "angle-resolved photoemission spectroscopy" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


301

Elastic properties of gamma-Pu by resonant ultrasound spectroscopy  

Science Conference Proceedings (OSTI)

Despite intense experimental and theoretical work on Pu, there is still little understanding of the strange properties of this metal. We used resonant ultrasound spectroscopy method to investigate the elastic properties of pure polycrystalline Pu at high temperatures. Shear and longitudinal elastic moduli of the {gamma}-phase of Pu were determined simultaneously and the bulk modulus was computed from them. A smooth linear and large decrease of all elastic moduli with increasing temperature was observed. We calculated the Poisson ratio and found that it increases from 0.242 at 519K to 0.252 at 571K.

Migliori, Albert [Los Alamos National Laboratory; Betts, J [Los Alamos National Laboratory; Trugman, A [Los Alamos National Laboratory; Mielke, C H [Los Alamos National Laboratory; Mitchell, J N [Los Alamos National Laboratory; Ramos, M [Los Alamos National Laboratory; Stroe, I [WORXESTER, MA

2009-01-01T23:59:59.000Z

302

Results from Point Contact Tunnelling Spectroscopy and Atomic Layer Deposition  

SciTech Connect

We have shown previously that magnetic niobium oxides can influence the superconducting density of states at the surface of cavity-grade niobium coupons. We will present recent results obtained by Point Contact Tunneling spectroscopy (PCT) on coupons removed from hot and cold spots in a niobium cavity, as well as a comparative study of magnetic oxides on mild baked/unbaked electropolished coupons. We will also describe recent results obtained from coated cavities, ALD films properties and new materials using Atomic Layer Deposition (ALD).

Proslier, Th. [Illinois Institute of Technology; Zasadzinski, J. [Illinois Institute of Technology; Ciovati, Gianluigi [JLAB; Kneisel, Peter K. [JLAB; Elam, J. W. [ANL; Norem, J. [ANL; Pellin, M. J. [ANL

2009-11-01T23:59:59.000Z

303

Excited-Nucleon Spectroscopy with 2+1 Fermion Flavors  

Science Conference Proceedings (OSTI)

We present progress made by the Hadron Spectrum Collaboration (HSC) in determining the tower of excited nucleon states using 2+1-flavor anisotropic clover lattices. The HSC has been investigating interpolating operators projected into irreducible representations of the cubic group in order to better calculate two-point correlators for nucleon spectroscopy; results are published for quenched and 2-flavor anisotropic Wilson lattices. In this work, we present the latest results using a new technique, distillation, which allows us to reach higher statistics than before. Future directions will be outlined at the end.

Cohen, Saul; Foley, Justin; Morningstar, Colin; Wong, Ricky; Edwards, Robert G; Joo, Balint; Richards, David G; Juge, Jimmy; Lin, Huey-Lin; Mathur, Nilmani; Peardon, Micheal J

2010-01-01T23:59:59.000Z

304

10 Questions for a Spectroscopy Expert: Nancy Hess | Department of Energy  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

Spectroscopy Expert: Nancy Hess Spectroscopy Expert: Nancy Hess 10 Questions for a Spectroscopy Expert: Nancy Hess April 14, 2011 - 4:34pm Addthis Nancy Hess | Photo Courtesy of Pacific Northwest National Lab (PNNL) Nancy Hess | Photo Courtesy of Pacific Northwest National Lab (PNNL) Niketa Kumar Niketa Kumar Public Affairs Specialist, Office of Public Affairs "I have always enjoyed the beauty and the complexity of processes in the natural world -- Spectroscopy gives you that insight." Nancy Hess, Spectroscopy Expert Meet Nancy Hess -- an expert in spectroscopy (i.e. the change in light intensity and/or frequency resulting from its interaction with matter that gives information about electronic structure, geometry and chemical bonds). At Pacific Northwest National Lab (PNNL), she leads the

305

Charge exchange spectroscopy as a fast ion diagnostic on TEXTOR  

SciTech Connect

An upgraded charge exchange spectroscopy diagnostic has been taken into operation at the TEXTOR tokamak. The angles of the viewing lines with the toroidal magnetic field are close to the pitch angles at birth of fast ions injected by one of the neutral beam injectors. Using another neutral beam for active spectroscopy, injected counter the direction in which fast ions injected by the first beam are circulating, we can simultaneously measure a fast ion tail on the blue wing of the D{sub {alpha}} spectrum while the beam emission spectrum is Doppler shifted to the red wing. An analysis combining the two parts of the spectrum offers possibilities to improve the accuracy of the absolute (fast) ion density profiles. Fast beam modulation or passive viewing lines cannot be used for background subtraction on this diagnostic setup and therefore the background has to be modeled and fitted to the data together with a spectral model for the slowing down feature. The analysis of the fast ion D{sub {alpha}} spectrum obtained with the new diagnostic is discussed.

Delabie, E.; Jaspers, R. J. E.; Hellermann, M. G. von [FOM-Rijnhuizen, EURATOM-FOM, NL-3430 BE Nieuwegein (Netherlands); Nielsen, S. K. [Association EURATOM-Risoe National Laboratory for Sustainable Energy, Technical University of Denmark, DK-4000 Roskilde (Denmark); Marchuk, O. [Forschungszentrum Juelich, EURATOM-FZJ, D-52424 Juelich (Germany)

2008-10-15T23:59:59.000Z

306

Mechanized selection of fiber optic arrays for spectroscopy measurements  

Science Conference Proceedings (OSTI)

A 400-fiber optic bundle has been installed as part of the beam emission spectroscopy diagnostic for measuring density fluctuations in Tokamak Fusion Test Reactor. One hundred bundles, each composed of four 1-mm-diam fibers, transmit {ital H}{sub {alpha}} light 50 m away to 20 detectors located outside the radiation area. To shorten the time spent manually switching the bundles among the 20 detectors, a mechanized fiber selector was installed. The fiber bundles were separated into radial and poloidal groups of 220 and 180 fibers and coupled by a computer-controlled, motorized precision translation stage. The fibers were fastened to a plate and placed less than 0.003 in. from an identical plate that holds a similar array of fibers which transmits the light to the detectors. Holding the fiber spacing tolerance to 0.001 in., and using refractive index matching fluid, the highest measured loss was less than 0.5 dB, and generally was very small compared to the fiber's insertion loss. The stages are actuated with precision encoded micrometers and controlled by the beam emission spectroscopy VAX-resident software via a RS-232/CAMAC interface allowing arbitrary selections of fibers between plasma discharges with a 5 min repetition rate.

Paul, S.F.; Cylinder, D.; Durst, R.D.; Fonck, R.J. (Plasma Physics Laboratory, Princeton University, Princeton, New Jersey 08543 (United States))

1992-10-01T23:59:59.000Z

307

Ultrafast X-ray and 2-dimensional UV Spectroscopy of TiO2 ...  

Science Conference Proceedings (OSTI)

Presentation Title, Ultrafast X-ray and 2-dimensional UV Spectroscopy of TiO2 Nanoparticles. Author(s), Majed Chergui. On-Site Speaker (Planned), Majed ...

308

Laser-induced breakdown spectroscopy as a diagnostic tool for coal fines.  

E-Print Network (OSTI)

??Laser Induced Breakdown Spectroscopy (LIBS) is a technique that uses a laser, to focus down and atomize a sample of desired material. Focusing of the… (more)

Aurelio, I. Andrew.

2005-01-01T23:59:59.000Z

309

Anatomy-Based Algorithms for Detecting Oral Cancer Using Reflectance and Fluorescence Spectroscopy  

E-Print Network (OSTI)

OBJECTIVES: We used reflectance and fluorescence spectroscopy to noninvasively and quantitatively distinguish benign from dysplastic/malignant oral lesions. We designed diagnostic algorithms to account for differences in ...

McGee, Sasha

310

Scanning angle Raman spectroscopy: Investigation of Raman scatter enhancement techniques for chemical analysis  

SciTech Connect

This thesis outlines advancements in Raman scatter enhancement techniques by applying evanescent fields, standing-waves (waveguides) and surface enhancements to increase the generated mean square electric field, which is directly related to the intensity of Raman scattering. These techniques are accomplished by employing scanning angle Raman spectroscopy and surface enhanced Raman spectroscopy. A 1064 nm multichannel Raman spectrometer is discussed for chemical analysis of lignin. Extending dispersive multichannel Raman spectroscopy to 1064 nm reduces the fluorescence interference that can mask the weaker Raman scattering. Overall, these techniques help address the major obstacles in Raman spectroscopy for chemical analysis, which include the inherently weak Raman cross section and susceptibility to fluorescence interference.

Meyer, Matthew W. [Ames Laboratory

2013-03-14T23:59:59.000Z

311

Characterization for the Onset of Crystallization of Amorphous to Microcrystalline Silicon by Optical Spectroscopies  

DOE Green Energy (OSTI)

We study the amorphous to microcrystalline silicon films made at three laboratories by using Raman, photoluminescence- and optical-abosrption spectroscopies.

Yue, G.; Han, D.; Ganguly, G.; Wang, Q.; Yang, J.; Guha, S.

2000-01-01T23:59:59.000Z

312

Characterization of the Electronic and Chemical Structure at the Thin Film Solar Cell Interfaces: June 2005 -- June 2009  

DOE Green Energy (OSTI)

Study using photoelectron spectroscopy, inverse photoemission, and X-ray absorption and emission to derive the electronic structure of interfaces in CIGSS and CdTe thin-film solar cells.

Heske, C.

2009-09-01T23:59:59.000Z

313

Untitled Document  

NLE Websites -- All DOE Office Websites (Extended Search)

to the related x-ray photoemission spectroscopy (XPS or ESCA) technique, where the photon energy is fixed and the electron intensity is measured as a function of electron kinetic...

314

Introducing many-body physics using atomic spectroscopy  

E-Print Network (OSTI)

Atoms constitute relatively simple many-body systems, making them suitable objects for developing an understanding of basic aspects of many-body physics. Photoabsorption spectroscopy is a prominent method to study the electronic structure of atoms and the inherent many-body interactions. In this article the impact of many-body effects on well-known spectroscopic features such as Rydberg series, Fano resonances, Cooper minima, and giant resonances is studied, and related many-body phenomena in other fields are outlined. To calculate photoabsorption cross sections the time-dependent configuration interaction singles (TDCIS) model is employed. The conceptual clearness of TDCIS in combination with the compactness of atomic systems allows for a pedagogical introduction to many-body phenomena.

Krebs, Dietrich; Santra, Robin

2013-01-01T23:59:59.000Z

315

Determination of Actinide Isotope Ratios Using Glow Discharge Optogalvanic Spectroscopy  

SciTech Connect

Diode-laser excited optogalvanic spectroscopy (OGS) of a glow discharge has been utilized to measure U-235/U-235 + U-238 isotope ratios. This ``optical mass spectrometric`` measurement has been demonstrated for a number of samples including uranium oxide, fluoride, and metal. Various diode-laser accessible atomic transitions in the 775 to 835 nm region have been evaluated; these transitions were chosen by considering OGS sensitivity and isotope shift. Using the 831.84 nm uranium line, for example, it was possible to measure the U-235/U-235 + U-238 isotope ratio (0.0026) of depleted uranium samples. A prototypical field instrument to make these measurements has been assembled and demonstrated. A U-236 spectral line was identified in a sample of enriched uranium, and an abundance sensitivity was measured.

Young, J.P.; Shaw, R.W.; Barshick, C.M.; Ramsey, J.M.

1997-08-01T23:59:59.000Z

316

Elemental analysis of slurry samples with laser induced breakdown spectroscopy  

Science Conference Proceedings (OSTI)

Direct analysis of wet slurry samples with laser induced breakdown spectroscopy (LIBS) is challenging due to problems of sedimentation, splashing, and surface turbulence. Also, water can quench the laser plasma and suppress the LIBS signal, resulting in poor sensitivity. The effect of water on LIBS spectra from slurries was investigated. As the water content decreased, the LIBS signal was enhanced and the standard deviation was reduced. To improve LIBS slurry analysis, dried slurry samples prepared by applying slurry on PVC coated slides were evaluated. Univariate and multivariate calibration was performed on the LIBS spectra of the dried slurry samples for elemental analysis of Mg, Si, and Fe. Calibration results show that the dried slurry samples give a good correlation between spectral intensity and elemental concentration.

Eseller, Kemal E.; Tripathi, Markandey M.; Yueh, Fang-Yu; Singh, Jagdish P.

2010-05-01T23:59:59.000Z

317

Low energy neutral spectroscopy during pulsed discharge cleaning in PLT  

DOE Green Energy (OSTI)

The efflux of neutral hydrogen from PLT during discharge cleaning has been measured using a time-of-flight spectrometer. During high ionization pulsed discharge cleaning (PDC), the flux in the energy range of 5 to 1000 eV varies from 10/sup 14/ H/sup 0//cm/sup 2/xs to 10/sup 16/ H/sup 0//cm/sup 2/xs and the average energy from 10 to 80 eV. The energy distributions are nearly single temperature Maxwellians. Low ionization PDC (Taylor-type) produces a 1000 times lower fluence in the same energy range; however, a flux of 10/sup 16/ H/sup 0//cm/sup 2/xs at energies less than 5 eV is inferred. The detailed submillisecond time variation of these parameters with the fill gas pressure and state of cleanliness of the machine is presented. Comparisons with UV spectroscopy, bolometric measurements, and residual gas analysis are made.

Ruzic, D.; Cohen, S.; Denne, B.; Schivell, J.

1983-04-01T23:59:59.000Z

318

Direct speciation of metal and metalloid ions by optical spectroscopies  

DOE Green Energy (OSTI)

Molecular level spectroscopic investigations of organic/inorganic interactions provide important new information on sedimentary geochemistry through the identification of interactions over moderate temperature and pH ranges. Although the official title of this project indicates the use of only optical spectroscopies, a combination of Uv/Vis/IR absorption, Raman scattering, and {sup 29}Si and {sup 13}C nuclear magnetic resonance (NMR) experiments are actually employed. A major advantage of integrating spectroscopic results with diagenesis studies is the ability to directly examine the mechanisms of interactions, even in complex matrices and with competing processes. Furthermore, we are extending these techniques to probe fluid inclusions with micro Raman and luminescence techniques to directly compare laboratory results with natural reservoir systems. 25 refs., 4 figs.

Tait, C.D.; Janecky, D.R.; Clark, D.L.; Ekberg, S.A.; Dixon, P.R.; Musgrave, J.A. (Los Alamos National Lab., NM (United States)); Bennett, P.C. (Texas Univ., Austin, TX (United States). Dept. of Geological Sciences)

1991-01-01T23:59:59.000Z

319

Graphene Thickness Determination Using Reflection and Contrast Spectroscopy  

E-Print Network (OSTI)

We have clearly discriminated the single-, bilayer-, and multiple-layer graphene (graphene sheet. We provide two easy-to-use methods to determine the number of graphene layers based on contrast spectra: a graphic method and an analytical method. We also show that the refractive index of graphene is different from that of graphite. The results are compared with those obtained using Raman spectroscopy. The recent success in extracting graphite sheets in multiple layers, and even monolayer graphene, from highly ordered pyrolytic graphite (HOPG) using a technique called micromechanical cleavage 1,2 has stimulated great interest in both the fundamental physics study and the potential applications of graphene. 3 Graphene has a two-dimensional (2D) crystal structure, which is the basic building block for other sp 2

Z. H. Ni; H. M. Wang; J. Kasim; H. M. Fan; T. Yu; Y. H. Wu; Y. P. Feng; Z. X. Shen

2007-01-01T23:59:59.000Z

320

Application of nonlinear wave modulation spectroscopy to discern material damage  

SciTech Connect

Materials containing structural damage have a far greater nonlinear elastic response than materials with no structural damage. This is the basis for nonlinear wave diagnostics of damage, methods which are remarkably sensitive to the detection and progression of damage in materials. Here the authors describe one nonlinear method, the application of harmonics and sum and difference frequency to discern damage in materials. The method is termed Nonlinear Wave Modulation Spectroscopy (NWMS). It consists of exciting a sample with continuous waves of two separate frequencies simultaneously, and inspecting the harmonics of the two waves, and their sum and difference frequencies (sidebands). Undamaged materials are essentially linear in their response to the two waves, while the same material, when damaged, becomes highly nonlinear, manifested by harmonics and sideband generation. The authors illustrate the method by experiments on uncracked and cracked plexiglass and sandstone samples, and by applying it to intact and damaged engine components.

Johnson, P.A. [Los Alamos National Lab., NM (United States); Sutin, A. [Stevens Inst. of Tech., Hoboken, NJ (United States); Abeele, K.E.A. van den [Catholic Univ. Leuven (Belgium). Dept. of Building Physics

1999-04-01T23:59:59.000Z

Note: This page contains sample records for the topic "angle-resolved photoemission spectroscopy" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


321

Experimental Study of Hypernuclei Electroproduction by High Precision Spectroscopy  

SciTech Connect

Jlab experiment E01-011, carried out in 2005 in JLab Hall C, is the second generation of the hypernuclear spectroscopy experiments by the (e,e{prime}K{sup +}) reaction. The (e,e{prime}K{sup +}) reaction is complimentary to the associated production reactions (K{sup -},{pi}{sup -}), ({pi}{sup +},K{sup +}) since, due to a larger momentum transfer to a hyperon, excitations of both spin-non-flip and spin-flip states are possible. The experiment uses high quality and continuous primary electron beam to produce neutron rich hypernuclei on various targets by the electroproduction. The experimental setup consists of splitter magnet, high resolution kaon spectrometer (HKS) and electron spectrometer (Enge) implemented in new configuration, the so called 'Tilt Method'. Production data was taken on multiple targets: CH{sub 2}, {sup 6}Li, {sup 7}Li, {sup 9}Be, {sup 10}B, {sup 12}C and {sup 28}Si. In present study the analysis of CH{sub 2}, {sup 12}C and {sup 28}Si is presented. The elementary processes of p(e,e{prime}K{sup +}){Lambda}/{Sigma} from CH{sup 2} data were used for calibration of the spectrometer optics and kinematics. The hypernuclear spectra of {sup 12}{sub {Lambda}}B was obtained with ground state resolution of 0.47 {+-} 0.07 MeV (FWHM), the best ever achieved. Feasibility of the electroproduction reaction to study medium to heavy targets has been proven with the first high resolution beyond p-shell hypernuclear spectra from {sup 28}{sub {Lambda}}Al hypernuclei. The obtained results of the E01-011 experiment confirmed that hypernuclear spectroscopy by the (e,e{prime}K{sup +}) reaction is a very useful technique.

Tomislav Seva

2009-12-01T23:59:59.000Z

322

Remote monitoring of volcanic gases using passive Fourier transform spectroscopy  

SciTech Connect

Volcanic gases provide important insights on the internal workings of volcanoes and changes in their composition and total flux can warn of impending changes in a volcano`s eruptive state. In addition, volcanoes are important contributors to the earth`s atmosphere, and understanding this volcanic contribution is crucial for unraveling the effect of anthropogenic gases on the global climate. Studies of volcanic gases have long relied upon direct in situ sampling, which requires volcanologists to work on-site within a volcanic crater. In recent years, spectroscopic techniques have increasingly been employed to obtain information on volcanic gases from greater distances and thus at reduced risk. These techniques have included UV correlation spectroscopy (Cospec) for SO{sub 2} monitoring, the most widely-used technique, and infrared spectroscopy in a variety of configurations, both open- and closed-path. Francis et al. have demonstrated good results using the sun as the IR source. This solar occultation technique is quite useful, but puts rather strong restrictions on the location of instrument and is thus best suited to more accessible volcanoes. In order to maximize the flexibility and range of FTIR measurements at volcanoes, work over the last few years has emphasized techniques which utilize the strong radiance contrast between the volcanic gas plume and the sky. The authors have successfully employed these techniques at several volcanoes, including the White Island and Ruapehu volcanoes in New Zealand, the Kilauea volcano on Hawaii, and Mt. Etna in Italy. But Popocatepetl (5452 m), the recently re-awakened volcano 70 km southeast of downtown Mexico City, has provided perhaps the best examples to date of the usefulness of these techniques.

Love, S.P.; Goff, F.; Counce, D.; Schmidt, S.C. [Los Alamos National Lab., NM (United States); Siebe, C.; Delgado, H. [Univ. Nactional Autonoma de Mexico, Coyoacan (Mexico)

1999-06-01T23:59:59.000Z

323

Introduction to NMR Spectroscopy and Physics. C-13 NMR in more detail than "Summary" 83 Chem 355 Jasperse C-13 NMR  

E-Print Network (OSTI)

Introduction to NMR Spectroscopy and Physics. C-13 NMR in more detail than "Summary" 83 Chem 355 Jasperse C-13 NMR I. Introduction to Spectroscopy Spectroscopy involves gaining information from, the most important type of spectroscopy is "NMR" ("Nuclear Magnetic Resonance" spectroscopy). NMR

Jasperse, Craig P.

324

Reflectance Vis/NIR spectroscopy for nondestructive taste characterization of Valencia oranges  

Science Conference Proceedings (OSTI)

The feasibility of reflectance Vis/NIR spectroscopy was investigated for taste characterization of Valencia oranges based on taste attributes including soluble solids content (SSC) and titratable acidity (TA), as well as taste indices including SSC to ... Keywords: BrimA, Nondestructive, Taste, Valencia orange, Vis/NIR spectroscopy

Bahareh Jamshidi; Saeid Minaei; Ezzedin Mohajerani; Hassan Ghassemian

2012-07-01T23:59:59.000Z

325

Measurement of uranium enrichment by gamma spectroscopy: result of an experimental design  

E-Print Network (OSTI)

PAPER Measurement of uranium enrichment by gamma spectroscopy: result of an experimental design Gamma spectroscopy is commonly used in nuclear safeguards to measure uranium enrichment. An experimental design has been carried out for the measurement of uranium enrichment using this technique with different

326

Campuzano-081111 - Argonne National Laboratories, Materials Sicence  

NLE Websites -- All DOE Office Websites (Extended Search)

Campuzano-081111 Campuzano-081111 MATERIALS SCIENCE COLLOQUIUM SPEAKER: Professor Juan Carlos Campuzano University of Illinois at Chicago Materials Science Division Argonne National Laboratory TITLE: "How angle resolved photoemission can help us understand high temperature superconductivity and other complex states of matter" DATE: Thursday, August 11, 2011 TIME: 11:00 a.m. PLACE: Building 212 / A-157 HOST: Mike Norman Refreshments will be served at 10:45 a.m. ABSTRACT: All the physical, chemical, and mechanical properties of materials are controlled by electrons that occupy the highest energy level in solids, those near the Fermi energy. Many techniques were develop to study those electrons, leading to the great successes of condensed matter physics. Newer and complex materials, such as the high temperature

327

Extracting the Eliashberg Function  

NLE Websites -- All DOE Office Websites (Extended Search)

Extracting the Eliashberg Function Print Extracting the Eliashberg Function Print A multitude of important chemical, physical, and biological phenomena are driven by violations of the Born-Oppenheimer approximation (BOA), which decouples electronic from nuclear motion in quantum calculations of solids. Recent advances in experimental techniques combined with ever-growing theoretical capabilities now hold the promise of presenting an unprecedented picture of these violations. By means of high-resolution angle-resolved photoemission at the ALS and theoretical calculations, a multi-institutional collaboration that includes researchers from Oak Ridge National Laboratory, the University of Tennessee, Stanford University, and the ALS has obtained the first high-resolution spectroscopic images of the specific vibrational modes that couple to a given electronic state.

328

Polaron Coherence Condensation in Layered Colossal Resistive Manganites  

NLE Websites -- All DOE Office Websites (Extended Search)

Polaron Coherence Condensation in Layered Colossal Resistive Manganites Print Polaron Coherence Condensation in Layered Colossal Resistive Manganites Print Novel quantum phenomena, such as high-temperature superconductivity (HTSC) and colossal magnetoresistance (CMR), arise in certain materials where the interactions between electrons are very strong, but the mechanism driving their appearance remains a major puzzle. Now, angle-resolved photoemission findings from an international team led by researchers from Stanford University and the ALS provide the first direct spectroscopic evidence that the transition from insulator to metal in CMR manganese oxides (manganites) results from coherent "polaron condensation." The new findings also suggest that coherence-driven transitions are a generic controlling factor for novel quantum phenomena in doped transition-metal oxides.

329

Extracting the Eliashberg Function  

NLE Websites -- All DOE Office Websites (Extended Search)

Extracting the Eliashberg Extracting the Eliashberg Function Extracting the Eliashberg Function Print Wednesday, 23 February 2005 00:00 A multitude of important chemical, physical, and biological phenomena are driven by violations of the Born-Oppenheimer approximation (BOA), which decouples electronic from nuclear motion in quantum calculations of solids. Recent advances in experimental techniques combined with ever-growing theoretical capabilities now hold the promise of presenting an unprecedented picture of these violations. By means of high-resolution angle-resolved photoemission at the ALS and theoretical calculations, a multi-institutional collaboration that includes researchers from Oak Ridge National Laboratory, the University of Tennessee, Stanford University, and the ALS has obtained the first high-resolution spectroscopic images of the specific vibrational modes that couple to a given electronic state.

330

Polaron Coherence Condensation in Layered Colossal Resistive Manganites  

NLE Websites -- All DOE Office Websites (Extended Search)

Polaron Coherence Condensation Polaron Coherence Condensation in Layered Colossal Resistive Manganites Polaron Coherence Condensation in Layered Colossal Resistive Manganites Print Wednesday, 30 July 2008 00:00 Novel quantum phenomena, such as high-temperature superconductivity (HTSC) and colossal magnetoresistance (CMR), arise in certain materials where the interactions between electrons are very strong, but the mechanism driving their appearance remains a major puzzle. Now, angle-resolved photoemission findings from an international team led by researchers from Stanford University and the ALS provide the first direct spectroscopic evidence that the transition from insulator to metal in CMR manganese oxides (manganites) results from coherent "polaron condensation." The new findings also suggest that coherence-driven transitions are a generic controlling factor for novel quantum phenomena in doped transition-metal oxides.

331

Polaron Coherence Condensation in Layered Colossal Resistive Manganites  

NLE Websites -- All DOE Office Websites (Extended Search)

Polaron Coherence Condensation in Layered Colossal Resistive Manganites Print Polaron Coherence Condensation in Layered Colossal Resistive Manganites Print Novel quantum phenomena, such as high-temperature superconductivity (HTSC) and colossal magnetoresistance (CMR), arise in certain materials where the interactions between electrons are very strong, but the mechanism driving their appearance remains a major puzzle. Now, angle-resolved photoemission findings from an international team led by researchers from Stanford University and the ALS provide the first direct spectroscopic evidence that the transition from insulator to metal in CMR manganese oxides (manganites) results from coherent "polaron condensation." The new findings also suggest that coherence-driven transitions are a generic controlling factor for novel quantum phenomena in doped transition-metal oxides.

332

SRS Research - Argonne National Laboratories, Materials Sicence Division  

NLE Websites -- All DOE Office Websites (Extended Search)

Research Research Synchrotron Radiation Studies Research Overview This program develops new capabilities using the nation's synchrotron radiation facilities and applies them to cutting-edge problems in materials science. In particular, we aim to play a leading scientific role at the Advanced Photon Source (APS). X-ray scattering studies take advantage of the high brilliance APS x-ray source for in-situ and time-resolved studies of surface and thin film structure. These include investigations of synthesis processes such as vapor-phase epitaxy and electrochemical deposition, and studies of electric-field-driven ferroelectric domain dynamics. High-resolution angle-resolved photoemission is used to understand the nature of superconductivity in the hi-Tc materials. New thrusts focus on exploring science enabled by future facilities such as

333

DovERA-65)q---7- Final Report Theoretical Studies of Magnetic Systems  

NLE Websites -- All DOE Office Websites (Extended Search)

DovERA-65)q---7- DovERA-65)q---7- Final Report - Theoretical Studies of Magnetic Systems ' L. P. Gor'kov M. A. Novotny J. R. Schrieffer endpoint to the pub lication or Ve have *no o bjection fro g s a patent August 1, 1994 - November 30, 19gssen tination of this materials. l'e altYYQA(A.,-' '-a- 1 0 9 f National High Magnetic Field Labora Florida State University / _,iktiI,,, Fez, of Intellectual 1800 E Paul Dirac Dr. Property Counsel I. During the grant period we have studied five areas of research, 1) low dimensional ferrimagnets, 2) lattice effects in the mixed valence problem, 3) spin compensation in the one dimensional Kondo lattice, 4) the interaction of quasi particles in short coherence length superconductors, and 5) novel effects in angle resolved photoemission spectra from nearly

334

What Controls the Phase Diagram and Superconductivity in Ru-Substituted BaFe2As2?  

SciTech Connect

We use high resolution angle-resolved photoemission to study the electronic structure of the iron based high-temperature superconductors Ba(Fe{sub 1-x}Ru{sub x}){sub 2}As{sub 2} as a function of Ru concentration. We find that substitution of Ru for Fe is isoelectronic, i.e., it does not change the value of the chemical potential. More interestingly, there are no measured, significant changes in the shape of the Fermi surface or in the Fermi velocity over a wide range of substitution levels (0 < x < 0.55). Given that the suppression of the antiferromagnetic and structural phase is associated with the emergence of the superconducting state, Ru substitution must achieve this via a mechanism that does not involve changes of the Fermi surface. We speculate that this mechanism relies on magnetic dilution which leads to the reduction of the effective Stoner enhancement.

Dhaka, R. S.; Liu, Chang; Fernandes, R.M.; Jiang, Riu; Strehlow, C.P.; Kondo, Takeshi; Thaler, A.; Schmalian, Joerg; Bud-ko, S.J.; Canfield, P.C.; Kaminski, A.

2011-12-23T23:59:59.000Z

335

Subband Structure of a Two-Dimensional Electron Gas Formed at the Polar Surface of the Strong Spin-Orbit Perovskite KTaO3  

SciTech Connect

We demonstrate the formation of a two-dimensional electron gas (2DEG) at the (100) surface of the 5d transition-metal oxide KTaO{sub 3}. From angle-resolved photoemission, we find that quantum confinement lifts the orbital degeneracy of the bulk band structure and leads to a 2DEG composed of ladders of subband states of both light and heavy carriers. Despite the strong spin-orbit coupling, we find no experimental signatures of a Rashba spin splitting, which has important implications for the interpretation of transport measurements in both KTaO{sub 3}- and SrTiO{sub 3}-based 2DEGs. The polar nature of the KTaO{sub 3}(100) surface appears to help mediate formation of the 2DEG as compared to non-polar SrTiO{sub 3}(100).

King, P.D.C.

2012-03-01T23:59:59.000Z

336

Polaron Coherence Condensation in Layered Colossal Resistive Manganites  

NLE Websites -- All DOE Office Websites (Extended Search)

Polaron Coherence Condensation in Layered Colossal Resistive Manganites Print Polaron Coherence Condensation in Layered Colossal Resistive Manganites Print Novel quantum phenomena, such as high-temperature superconductivity (HTSC) and colossal magnetoresistance (CMR), arise in certain materials where the interactions between electrons are very strong, but the mechanism driving their appearance remains a major puzzle. Now, angle-resolved photoemission findings from an international team led by researchers from Stanford University and the ALS provide the first direct spectroscopic evidence that the transition from insulator to metal in CMR manganese oxides (manganites) results from coherent "polaron condensation." The new findings also suggest that coherence-driven transitions are a generic controlling factor for novel quantum phenomena in doped transition-metal oxides.

337

Bum Joon Kim - Argonne National Laboratories, Materials Sicence Division  

NLE Websites -- All DOE Office Websites (Extended Search)

EM > Bum Joon Kim EM > Bum Joon Kim Bum Joon Kim Assistant Physicist Bldg. 223, A-129 Phone: 630-252-5347 This e-mail address is being protected from spambots. You need JavaScript enabled to view it. Biography Bumjoon ("BJ") Kim is a staff scientist in the Material Science Division. He received B. A. from Korea Advanced Institute of Science and Technology in 1999 and Ph. D. from Seoul National University in 2005. His thesis involved angle-resolved photoemission (ARPES) studies of transition-metal oxides. Before joining MSD in 2010, he held postdoctoral position in University of Michigan and visiting assistant professor in University of Tokyo. His current research focuses on 5d transition-metal oxides, in which strong spin-orbit coupling and correlation effects conspire to realize novel phases of matter. His research program encompasses single crystal growth and characterizations, elastic and inelastic x-ray scattering, and ARPES.

338

Absorption spectroscopy in hollow-glass waveguides using infrared laser diodes  

Science Conference Proceedings (OSTI)

Hollow-glass waveguides may be a viable technology that, in some cases, may supplant heavier multi-pass cells such as White or Herriott cells for performing trace detection using tunable diode laser absorption spectroscopy. We report here a series of experiments for testing the suitability of waveguides for infrared spectroscopy. The loss characteristics of 1 mm bore diameter waveguides have been measured for straight and coiled lengths. Using direct absorption spectroscopy we have found that the absorption pathlength is approximately equal to the physical length of the waveguide. Broadband FM diode laser spectroscopy produces a comparable signal-to-noise ratio with less than a second of signal averaging. Finally, we have also performed near-infrared spectroscopy of nitrous oxide flowing through a waveguide using a telecommunications diode laser.

Blake, Thomas A.; Kelly, James F.; Stewart, Timothy L.; Hartman, John S.; Sharpe, Steven W.; Sams, Robert L.

2002-07-10T23:59:59.000Z

339

Summary report of FY 1995 Raman spectroscopy technology development  

Science Conference Proceedings (OSTI)

US DOE is sponsoring development of remote, fiber-optic Raman spectroscopy for rapid chemical characterization of Hanford high-level radioactive tank waste. Deployment targets for this technology are analytical hot cells and, via the Light-Duty Utility Arm and cone penetrometer, the waste tanks themselves. Perceived benefits of fiber-optic Raman spectroscopy are (1) rapid generation of tank-waste safety-related data, (2) reduced personnel exposure to highly radioactive waste, (3) reduced tank-waste sampling and analysis costs, and (4) reduced radioactive analytical waste. This document presents the results from the investigation of two dispersive, transmission-grating Raman systems and four fiber-optic Raman probe designs with non-radioactive tank waste simulants. One Raman system used a 532-nm, 400 mW, solid-state laser; the other used a 785-nm, 500 mW, solid-state diode laser. We found (1) the transmission-grating systems had better wavelength stability than previously tried Czerny-Turner-Based systems and (2) the 785-nm system`s specie detection limits in the spectral fingerprint regiion were at least as good as those for the 532-nm system. Based on these results, and the fact that some tank wastes luminesce with 514.5nm excitation, we selected the 785-nm system for hot-cell use. Of the four probes tested, three had a ``six-around-on`` fiber probe design; the fourth probe was a one-fiber-in-one-fiber-out, diffuse-relectance design. Comparison of the four probes` signal-to-noise rations, rations, transmission/collection efficiencies, and probe-silica Raman backgrounds showed that the best probe for use with Hanford-Site tank waste should (1) be filtered as close to the probe tip as possible to reduce the probe-silica Raman background and (2) have multiple collection fibers. The responses of all the probes tested showed a strong dependence on probe-sample distance, and the presence of a probe window appeared to increase the probe`s silica Raman background.

Douglas, J.G.

1995-11-01T23:59:59.000Z

340

Assaying protein import into mitochondria using fluorescence spectroscopy  

E-Print Network (OSTI)

Most proteins residing in the mitochondrial matrix are synthesized in the cytosol and post-translationally imported into the mitochondrial matrix. The matrix-targeted preproteins traverse the outer mitochondrial membrane (OM) via the Translocase of the Outer Membrane (TOM) complex, and the inner mitochondrial membrane (IM) via the Translocase of the Inner Membrane 23 (TIM23) complex. A novel system was set up to examine the import of matrix-targeted preproteins into mitochondria using fluorescence spectroscopy. The fluorescent probe 6-(7-nitrobenz-2-oxa-1,3-diazol-4- yl)aminohexanoic acid (NBD) was site-specifically incorporated into different positions along the model matrix protein Su9-DHFR. The fluorescent-labeled polypeptides were either fully imported into isolated mitochondria or were arrested along the translocation pathway by the binding of methotrexate (MTX) to the DHFR moiety, creating NBDSu9- DHFRÂ?MTX import intermediates. The NBD-Su9-DHFR polypeptides were able to be fully imported into the mitochondrial matrix in the absence of MTX, and were inaccessible to externally-added iodide ion quenchers. Treatment of the mitochondria with the pore-forming antibiotic alamethicin allowed the iodide ion quenchers access to the matrix through pores in the inner membrane (IM). After Alamethicin treatment the fully-imported NBD-Su9-DHFR polypeptides were accessible to the externally-added iodide ions. The extent of collisional quenching of the NBD fluorophores by the iodide ions was measured as the Stern-Volmer quenching constant, Ksv. Ksv values were obtained for the NBD-Su9-DHFR polypeptides in the presence of MTX (import intermediates) or in the absence of MTX (fully-imported). The Ksv values for NBD-Su9- DHFR import intermediates were similar, despite the location of the NBD probe along the translocation pathway. These Ksv values were similar to those obtained for the fullyimported NBD-Su9-DHFR polypeptides (-MTX). The locations of the varying probe positions along the import pathway were addressed using chemical crosslinking of Su9- DHFR Cys mutants. The use of fluorescence spectroscopy, in association with chemical crosslinking, to analyze the mitochondrial protein import pathways will prove a useful tool to probe the environment of the nascent chain as it is crossing the import pathway (the TOM, TIM23 complexes).

Cargill, Holly Beth

2003-05-01T23:59:59.000Z

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341

Development of laser induced breakdown spectroscopy instrumentatin for safeguards applications  

DOE Green Energy (OSTI)

In September 2006, a Technical Meeting on Application of Laser Spectrometry Techniques in IAEA Safeguards was held at IAEA headquarters (HQ). One of the principal recommendations from this meeting was the need to 'pursue the development of novel complementary access instrumentation based on laser induced breakdown spectroscopy (LIBS) for the detection of gaseous and solid signatures and indicators of nuclear fuel cycle processes and associated materials.' Pursuant to this recommendation the Department of Safeguards (SG) under the Division of Technical Support (SGTS) convened the Experts and Users Advisory Meeting on Laser Induced Breakdown Spectroscopy (LIBS) for Safeguards Applications. This meeting was held at IAEA HQ from July 7-11,2008 and hosted by the Novel Technologies Unit (NTU). The meeting was attended by 12 LIBS experts from the Czech Republic, the European Commission, France, the Republic of Korea, the United States of America, Germany, the United Kingdom of Great Britain, Canada, and Northern Ireland. After a presentation of the needs of the IAEA inspectors, the LIBS experts were in agreement that needs as presented could be partially or fully fulfilled using LIBS instrumentation. The needs of the IAEA inspectors were grouped in the following broad categories: (1) Improvements to in-field measurements/environmental sampling; (2) Monitoring status of activity in a Hot Cell; (3) Verifying status of activity at a declared facility via process monitoring; and (4) Need for pre-screening of environmental samples before analysis. Under the Department of Energy/National Nuclear Security Administration (DOE/NNSA) Next Generation Safeguards Initiative (NGSI) Los Alamos National Laboratory is exploring three potential applications of LIBS for international safeguards. As part of this work, we are developing: (1) a user-friendly man-portable LIBS system to characterize samples across a wide range of elements in the periodic table from hydrogen up to heavy elements like plutonium and uranium; (2) a LIBS system that can be deployed in harsh environments such as gloveboxes and hot cells providing relative compositional analysis of process streams for example ratios like Cm/Pu and Cm/U; and (3) an inspector field deployable system that can be used to analyze the elemental composition of microscopic quantities of samples containing plutonium and uranium. In this paper we will describe our current development and performance testing results both in a fixed lab and measurements in field deployable configurations using LIBS instrumentation developed for applications to international safeguards.

Barefield Il, James E [Los Alamos National Laboratory; Clegg, Samuel M [Los Alamos National Laboratory; Le, Loan A [Los Alamos National Laboratory; Lopez, Leon N [Los Alamos National Laboratory

2010-01-01T23:59:59.000Z

342

Fundamental Photoemission Brightness Limit from Disorder Induced Heating  

E-Print Network (OSTI)

We determine the limit of the highest achievable photoemitted electron brightness, due to heating just after emission into vacuum, applicable to both relativistic and nonrelativistic photoelectron production. This heating is due to poorly screened Coulomb interactions equivalent to disorder induced heating seen in ultracold neutral plasmas. Owing to the multi-scale nature of the initial interactions of such systems, an N-body tree algorithm is used to compute the universal scaling of the disorder induced heating in fully contained bunches, and is shown to agree well with a simple model utilizing the tabulated correlated energy of one component plasmas. We also present simulations for beams undergoing Coulomb explosion at the photocathode, and demonstrate that both the temperature growth and subsequent cooling must be characterized by correlated effects, as well as correlation-frozen dynamics. In either case, the induced temperature is found to be of several meV for typical photoinjector beam densities, a sign...

Maxson, Jared; Coleman-Smith, Christopher; Wan, Weishi; Padmore, Howard

2013-01-01T23:59:59.000Z

343

Photoemission with Chemical Potential from QCD Gravity Dual  

E-Print Network (OSTI)

We consider a $D4-D8-\\bar D8$ brane construction which gives rise to a large N QCD at sufficiently small energies. Using the gravity dual of this system, we study chiral phase transition at finite chemical potential and temperature and find a line of first order phase transitions in the phase plane. We compute the spectral function and the photon emission rate. The trace of the spectral function is monotonic at vanishing chemical potential, but develops some interesting features as the value of the chemical potential is increased.

Andrei Parnachev; David A. Sahakyan

2006-10-23T23:59:59.000Z

344

Schottky-Enabled Photoemission and Dark Current Measurements...  

NLE Websites -- All DOE Office Websites (Extended Search)

USA TUPPD069 03 Particle Sources and Alternative Acceleration Techniques T02 Electron Sources ISBN 978-3-95450-115-1 1563 Copyright c 2012 by IEEE - cc Creative...

345

Method of using a nuclear magnetic resonance spectroscopy standard  

DOE Patents (OSTI)

(CH.sub.3).sub.3 SiNSO is produced by the reaction of ((CH.sub.3).sub.3 Si).sub.2 NH with SO.sub.2. Also produced in the reaction are ((CH.sub.3).sub.3 Si).sub.2 O and a new solid compound [NH.sub.4 ][(CH.sub.3).sub.3 SiOSO.sub.2 ]. Both (CH.sub.3).sub.3 SiNSO and [NH.sub.4 ][(CH.sub.3).sub.3 SiOSO.sub.2 ] have fluorescent properties. The reaction of the subject invention is used in a method of measuring the concentration of SO.sub.2 pollutants in gases. By the method, a sample of gas is bubbled through a solution of ((CH.sub.3).sub.3 Si).sub.2 NH, whereby any SO.sub.2 present in the gas will react to produce the two fluorescent products. The measured fluorescence of these products can then be used to calculate the concentration of SO.sub.2 in the original gas sample. The solid product [NH.sub.4 ][(CH.sub.3).sub.3 SiOSO.sub.2 ] may be used as a standard in solid state NMR spectroscopy, wherein the resonance peaks of either .sup.1 H, .sup.13 C, .sup.15 N, or .sup.29 Si may be used as a reference.

Spicer, Leonard D. (Salt Lake City, UT); Bennett, Dennis W. (Clemson, SC); Davis, Jon F. (Salt Lake City, UT)

1985-01-01T23:59:59.000Z

346

Surface enhanced Raman spectroscopy for microfluidic pillar arrayed separation chips  

SciTech Connect

Numerous studies have addressed the challenges of implementing miniaturized microfluidic platforms for chemical and biological separation applications. However, the integration of real time detection schemes capable of providing valuable sample information under continuous, ultra low volume flow regimes has not fully been addressed. In this report we present a chip based chromatography system comprising of a pillar array separation column followed by a reagent channel for passive mixing of a silver colloidal solution into the eluent stream to enable surface enhanced Raman spectroscopy (SERS) detection. Our design is the first integrated chip based microfluidic device to combine pressure driven separation capability with real time SERS detection. With this approach we demonstrate the ability to collect distinctive SERS spectra with or without complete resolution of chromatographic bands. Computational fluidic dynamic (CFD) simulations are used to model the diffusive mixing behavior and velocity profiles of the two confluent streams in the microfluidic channels. We evaluate the SERS spectral band intensity and chromatographic efficiency of model analytes with respect to kinetic factors as well as signal acquisition rates. Additionally, we discuss the use of a pluronic modified silver colloidal solution as a means of eliminating contamination generally caused by nanoparticle adhesion to channel surfaces.

Taylor, Lisa [University of Tennessee, Knoxville (UTK); Kirchner, Teresa B [ORNL; Lavrik, Nickolay V [ORNL; Sepaniak, Michael [University of Tennessee, Knoxville (UTK)

2012-01-01T23:59:59.000Z

347

Visible spectroscopy in the DIII-D divertor  

SciTech Connect

Spectroscopy measurements in the DIII-D divertor have been carried out with a survey spectrometer which provides simultaneous registration of the visible spectrum over the region 400--900 nm with a resolution of 0.2 nm. Broad spectral coverage is achieved through use of a fiberoptic transformer assembly to map the curved focal plane of a fast (f/3) Rowland-circle spectrograph into a rastered format on the rectangular sensor area of a two-dimensional CCD camera. Vertical grouping of pixels during CCD readout integrates the signal intensity over the height of each spectral segment in the rastered image, minimizing readout time. For the full visible spectrum, readout time is 50 ms. Faster response time (< 10 ms) may be obtained by selecting for readout just a small number of the twenty spectral segments in the image on the CCD. Simultaneous recording of low charge states of carbon, oxygen and injected impurities has yielded information about gas recycling and impurity behavior at the divertor strike points. Transport of lithium to the divertor region during lithium pellet injection has been studied, as well as cumulative deposition of lithium on the divertor targets from pellet injection over many successive discharges.

Brooks, N.H. [General Atomics, San Diego, CA (United States); Fehling, D.; Hillis, D.L.; Klepper, C.C. [Oak Ridge National Lab., TN (United States); Naumenko, N. [Inst. of Physics, Minsk (Belarus); Tugarinov, S. [TRINITI Lab., Troitsk (Russian Federation); Whyte, D.G. [INRS-Energie et Materiaux, Varennes, Quebec (Canada)

1996-06-01T23:59:59.000Z

348

Single-molecule force spectroscopy: Practical limitations beyond Bell's model  

E-Print Network (OSTI)

Single-molecule force spectroscopy experiments, as well as a number of other physical systems, are governed by thermally activated transitions out of a metastable state under the action of a steadily increasing external force. The main observable in such experiments is the distribution of the forces, at which the escape events occur. The challenge in interpreting the experimental data is to relate them to the microscopic system properties. We work out a maximum likelihood approach and show that it is the optimal method to tackle this problem. When fitting actual experimental data it is unavoidable to assume some functional form for the force-dependent escape rate. We consider a quite general and common such functional form and demonstrate by means of data from a realistic computer experiment that the maximum number of fit parameters that can be determined reliably is three. They are related to the force-free escape rate and the position and height of the activation barrier. Furthermore, the results for the first two of these fit parameters show little dependence on the assumption about the manner in which the barrier decreases with the applied force, while the last one, the barrier height in the absence of force, depends strongly on this assumption.

Sebastian Getfert; Mykhaylo Evstigneev; Peter Reimann

2008-05-19T23:59:59.000Z

349

Alignment of the photoelectron spectroscopy beamline at NSRL  

E-Print Network (OSTI)

The photoelectron spectroscopy beamline at National Synchrotron Radiation Laboratory (NSRL) is equipped with a spherical grating monochromator with the included angle of 174 deg. Three gratings with line density of 200, 700 and 1200 lines/mm are used to cover the energy region from 60 eV to 1000 eV. After several years operation, the spectral resolution and flux throughput were deteriorated, realignment is necessary to improve the performance. First, the wavelength scanning mechanism, the optical components position and the exit slit guide direction are aligned according to the design value. Second, the gratings are checked by Atomic Force Microscopy (AFM). And then the gas absorption spectrum is measured to optimize the focusing condition of the monochromator. The spectral resolving power is recovered to the designed value of 1000@244eV. The flux at the end station for the 200 lines/mm grating is about 10^10 photons/sec/200mA, which is in accordance with the design. The photon flux for the 700 lines/mm grati...

Li, Chaoyang; Wen, Shen; Pan, Congyuan; An, Ning; Du, Xuewei; Zhu, Junfa; Wang, Qiuping

2013-01-01T23:59:59.000Z

350

Hyperfine Structure Measurements of Antiprotonic $^3$He using Microwave Spectroscopy  

E-Print Network (OSTI)

The goal of this project was to measure the hyperfine structure of $\\overline{\\text{p}}^3$He$^+$ using the technique of laser-microwave-laser spectroscopy. Antiprotonic helium ($\\overline{\\text{p}}$He$^+$) is a neutral exotic atom, consisting of a helium nucleus, an electron and an antiproton. The interactions of the angular momenta of its constituents cause a hyperfine splitting ({HFS}) within the energy states of this new atom. The 3\\% of formed antiprotonic helium atoms which remain in a metastable, radiative decay-dominated state have a lifetime of about 1-3~$\\mu$s. This time window is used to do spectroscopic studies. The hyperfine structure of $\\overline{\\text{p}}^4$He$^+$ was already extensively investigated before. From these measurements the spin magnetic moment of the antiproton can be determined. A comparison of the result to the proton magnetic moment provides a test of {CPT} invariance. Due to its higher complexity the new exotic three-body system of $\\overline{\\text{p}}^3$He$^+$ is a cross-check...

Friedreich, Susanne

351

Hadron spectroscopy in diffractive and central production processes at COMPASS  

SciTech Connect

COMPASS is a fixed-target experiment using secondary high-energetic hadron beams provided by the CERN SPS. In 2008 and 2009, a large amount of data has been collected with a 190 GeV/c pion beam for the investigation of the hadron spectrum in diffractive and central production processes. A big variety of observed final states, including {pi}{sup -}{pi}{sup +}{pi}{sup -}, {pi}{sup -}{pi}{sup 0}{pi}{sup 0}, {pi}{sup -}{eta}{eta}, {pi}{sup -}K{sub s}K{sub s}, {pi}{sup -}K{sup +}K{sup -}, K{sup -}{pi}{sup +}{pi}{sup -}, and centrally produced 4{pi}, is being analysed. The potential for systematic spectroscopic studies especially concerning the existence and nature of spin-exotic, hybrid and glueball states is discussed. In addition, we show the first results from the data set collected with a proton beam in 2008. These data indicate the chance of COMPASS to contribute to the field of baryon spectroscopy.

Jasinski, Prometeusz Kryspin [Institut fuer Kernphysik, 55128 - Mainz University (Germany)

2011-07-15T23:59:59.000Z

352

Simulated X-Ray Absorption Spectroscopy on the Water Dimer  

DOE Green Energy (OSTI)

The ability of an individual H{sub 2}O molecule to form multiple hydrogen bonds with neighboring molecules makes it an ideal substance for the study of hydrogen bonding. X-ray absorption spectroscopy (XAS) can be used to study what intermolecular structures the hydrogen-bonded water molecules form. XAS excites core electrons from the oxygen 1 s atomic orbital to an unoccupied orbital. The resulting absorption spectrum shows the energy levels of the unoccupied orbitals, which in turn is dependent on the intermolecular structure of the H{sub 2}O system. Previous studies using molecular dynamics computer simulations have concluded that the intermolecular structure of liquid water is a distorted tetrahedron. Yet x-ray absorption spectra show discrepancies between liquid water and ice Ih, which is already known to have a rigid tetrahedral structure. The research group, which is based in the University of Sweden in Stockholm and the Stanford Synchrotron Radiation Laboratory at the Stanford Linear Accelerator Center, has studied the possible presence of broken hydrogen bonds in the liquid water intermolecular structure to explain these deviations. Computer simulations are used to construct theoretical absorption spectra for models of liquid water including broken hydrogen bonds. Creating such models requires controlling variables. The simplest method of isolating individual variables, such as hydrogen bond length and angles, is to study the water dimer. Here, the water dimer is used to study how the absorption spectra change with the way the water molecules are positioned and oriented relative to each other.

Wung, A

2004-02-05T23:59:59.000Z

353

Integral field near-infrared spectroscopy of II Zw 40  

E-Print Network (OSTI)

We present integral field spectroscopy in the near-infrared of the nearby starburst galaxy IIZw40. Our new observations provide an unprecedented detailed view of the interstellar medium and star formation of this galaxy. The radiation emitted by the galaxy is dominated by a giant HII region, which extends over an area of more than 400 pc in size. A few clusters are present in this area, however one in particular appears to be the main source of ionizing photons. We derive the properties of this object and compare them with those of the 30 Doradus cluster in the Large magellanic cloud (LMC). We study the spatial distribution and velocity field of different components of the inetrstellar medium (ISM), mostly through the Bracket series lines, the molecular hydrogen spectrum, and [FeII]. We find that [FeII] and H2 are mostly photon excited, but while the region emitting [FeII] is almost coincident with the giant HII region observed in the lines of atomic H and He, the H2 has a quite different distribution in space and velocity. The age of the stellar population in the main cluster is such that no supernova (SN) should be present yet so that the gas kinematics must be dominated by the young stars. We do not see, in the starbursting region, any geometrical or dynamical structure that can be related to the large scale morphology of the galaxy.

L. Vanzi; G. Cresci; E. Telles; J. Melnick

2008-03-17T23:59:59.000Z

354

Entanglement spectroscopy of SU(2)-broken phases in two dimensions  

E-Print Network (OSTI)

In magnetically ordered systems the breaking of SU(2) symmetry in the thermodynamic limit is associated with the appearance of a special type of low-lying excitations in finite size energy spectra, the so called tower of states (TOS). In the present work we numerically demonstrate that there is a correspondence between the SU(2) tower of states and the lower part of the ground state entanglement spectrum (ES). Using state-of-the-art DMRG calculations, we examine the ES of the 2D antiferromagnetic J1-J2 Heisenberg model on both the triangular and kagom\\'e lattice. At large ferromagnetic J2 the model exhibits a magnetically ordered ground state. Correspondingly, its ES contains a family of low-lying levels that are reminiscent of the energy tower of states. Their behavior (level counting, finite size scaling in the thermodynamic limit) sharply reflects tower of states features, and is characterized in terms of an effective entanglement Hamiltonian that we provide. At large system sizes TOS levels are divided from the rest by an entanglement gap. Our analysis suggests that (TOS) entanglement spectroscopy provides an alternative tool for detecting and characterizing SU(2)-broken phases using DMRG.

F. Kolley; S. Depenbrock; I. P. McCulloch; U. Schollwöck; V. Alba

2013-07-24T23:59:59.000Z

355

Density fluctuation measurements via beam emission spectroscopy (invited)  

SciTech Connect

Previous studies of plasma microturbulence have indicated that the fluctuation power scales with radial wave number, {ital k}{sub {perpendicular}} , like {ital k}{sub {perpendicular}}{sup {minus}2}{r arrow}{ital k}{sub {perpendicular}}{sup {minus}3.5} for {ital k}{sub {perpendicular}} {ge}2 cm{sup {minus}1}. This implies that low {ital k} fluctuations may dominate the spectrum. Beam emission spectroscopy (BES) has been developed to provide spatially localized measurements of density fluctuations in this low {ital k} region of the spectrum ({ital k}{sub {perpendicular}} {le}2 cm{sup {minus}1}). A 20-channel system has been installed on TFTR which images one of the heating neutral beams (via fiber optics) onto a set of photoconductive photodiode detectors. Fluctuations in the fluorescent {ital D}{sub {alpha}} emission from the beam can be related to the local plasma density fluctuations via a model of the atomic excitation processes. The analysis of BES data utilizes many of the standard statistical analysis techniques such as power spectra, coherency and cross phase, and correlation analysis which are also used in the analysis of, for example, Langmuir probe data. In the case of BES however, these techniques require some special modifications to account for systematic effects such as photon statistics and fluctuations in the neutral beam density induced by the strong fluctuations near the plasma edge.

Durst, R.D.; Fonck, R.J.; Cosby, G.; Evensen, H. (University of Wisconsin/Madison, Madison, Wisconsin 53706 (United States)); Paul, S.F. (Princeton Plasma Physics Laboratory, Princeton University, Princeton, New Jersey 08541 (United States))

1992-10-01T23:59:59.000Z

356

Plutonium Isotopic Measurements by Gamma-Ray Spectroscopy  

SciTech Connect

The nondestructive assay of plutonium is important as a safeguard tool in accounting for stategic nuclear material. Several nondestructive assay techniques, e.g., calorimetry and spontaneous fission assay detectors, require a knowledge of plutonium and americium isotopic ratios to convert their raw data to total grams of plutonium. This paper describes a nondestructive technique for calculating plutonium-238, plutonium-240, plutonium-241 and americium-241 relative to plutonium-239 from measured peak areas in the high resolution gamma-ray spectra of solid plutonium samples. Gamma-ray attenuation effects have been minimized by selecting sets of neighboring peaks in the spectrum whose components are due to the different isotopes. Since the detector efficiencies are approximately the same for adjacent peaks, the accuracy of the isotopic ratios are dependent on the half-lives, branching intensities and measured peak areas. The data presented describes the results obtained by analyzing gamma-ray spectra in the energy region from 120 to 700 keV. The majority of the data analyzed was obtained from plutonium material containing 6% plutonium-240. Sample weights varied from 0.25 g to approximately 1.2 kg. The methods have also been applied to plutonium samples containing up to 23% plutonium-240 with weights of 0.25 to 200g. Results obtained by gamma-ray spectroscopy are compared to chemical analyses of aliquots taken from the bulk samples.

Haas, Francis X.; Lemming, John F.

1976-05-01T23:59:59.000Z

357

In-Situ Measurement of Chirality of Molecules and Molecular Assemblies with Surface Nonlinear Spectroscopy  

Science Conference Proceedings (OSTI)

Developments in quantitative measurement and analysis in nonlinear surface spectroscopy, namely, second harmonic generation linear dichroism (SHG-LD) and sum frequency generation vibrational spectroscopy linear dichroism (SFG-VS-LD), provide new opportunities for probing the surface chirality of monolayers and thin films. In this book chapter, the up-to-date theoretical background and experimental methodology, as well as examples and future perspectives on the developments with surface nonlinear spectroscopy in surface chirality studies are to be summarized and outlined for general readers.

Wang, Hongfei

2012-01-11T23:59:59.000Z

358

Infrared Spectroscopy of Atomic Lines in Gaseous Nebulae  

E-Print Network (OSTI)

Spectroscopy in the infrared provides a means to assess important properties of the plasma in gaseous nebulae. We present some of our own work that illustrates the need for interactions between the themes of this conference - astronomical data, atomic data, and plasma simulations. We undertook Infrared Space Observatory (ISO) observations with the intent of better understanding the effects of density variations in nebulae, particularly planetary nebulae (PNs), by determining average electron densities from the flux ratios of several fine-structure, IR emission lines. Instead, we are able to ascertain only minor density information because of several instances of the observed line flux ratios being out of range of the theoretical predictions using current atomic data. In these cases, the ISO data cannot presently be used to derive electron density, but rather provide direction for needed improvements in the atomic collision strengths. We have detected an unidentified (uid) strong emission line in an ISO/SWS spectrum of the Orion Nebula. The line has a rest wavelength 2.89350$\\pm$0.00003 $\\mu$m. A long-slit UKIRT observation confirms the presence of this line and shows that the emission is spatially extended and appears to be coincident with the brightest part of the ionized region. We do not detect the uid line in our SWS02 spectra of any of the several bright PNs which we observed for a comparable time. The need for basic atomic data, in this case wavelengths to aid species identification, is paramount for future progress. We look toward the future with a brief synopsis of upcoming or planned IR missions.

R. H. Rubin; R. J. Dufour; T. R. Geballe; S. W. J. Colgan; J. P. Harrington; S. D. Lord; A. L. Liao; D. A. Levine

2001-09-23T23:59:59.000Z

359

Alignment of the photoelectron spectroscopy beamline at NSRL  

E-Print Network (OSTI)

The photoelectron spectroscopy beamline at National Synchrotron Radiation Laboratory (NSRL) is equipped with a spherical grating monochromator with the included angle of 174 deg. Three gratings with line density of 200, 700 and 1200 lines/mm are used to cover the energy region from 60 eV to 1000 eV. After several years operation, the spectral resolution and flux throughput were deteriorated, realignment is necessary to improve the performance. First, the wavelength scanning mechanism, the optical components position and the exit slit guide direction are aligned according to the design value. Second, the gratings are checked by Atomic Force Microscopy (AFM). And then the gas absorption spectrum is measured to optimize the focusing condition of the monochromator. The spectral resolving power is recovered to the designed value of 1000@244eV. The flux at the end station for the 200 lines/mm grating is about 10^10 photons/sec/200mA, which is in accordance with the design. The photon flux for the 700 lines/mm grating is about 5 X 10^8 photons/sec/200mA, which is lower than expected. This poor flux throughput may be caused by carbon contamination on the optical components. The 1200 lines/mm grating has roughness much higher than expected so the diffraction efficiency is too low to detect any signal. A new grating would be ordered. After the alignment, the beamline has significant performance improvements in both the resolving power and the flux throughput for 200 and 700 lines/mm gratings and is provided to users.

Chaoyang Li; Hanbin Pan; Shen Wen; Congyuan Pan; Ning An; Xuewei Du; Junfa Zhu; Qiuping Wang

2013-03-04T23:59:59.000Z

360

Geek-Up[6.10.10]: Attosecond Absorption Spectroscopy and Kinked Nanopores |  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

6.10.10]: Attosecond Absorption Spectroscopy and Kinked 6.10.10]: Attosecond Absorption Spectroscopy and Kinked Nanopores Geek-Up[6.10.10]: Attosecond Absorption Spectroscopy and Kinked Nanopores August 6, 2010 - 6:07pm Addthis A classical diagram of a krypton atom shows its 36 electrons arranged in shells. | Photo Courtesy of: Berkeley Lab. A classical diagram of a krypton atom shows its 36 electrons arranged in shells. | Photo Courtesy of: Berkeley Lab. Elizabeth Meckes Elizabeth Meckes Director of User Experience & Digital Technologies, Office of Public Affairs Thanks to the attosecond absorption spectroscopy process, an international team of scientists from Max Planck Institute of Quantum Optics (MPQ), Lawrence Berkeley National Laboratory and the University of California at Berkeley were able to observe an atom's electrons moving in real time -

Note: This page contains sample records for the topic "angle-resolved photoemission spectroscopy" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


361

Laser-Induced Breakdown Spectroscopy System Using a Passively Q-Switched Laser  

NLE Websites -- All DOE Office Websites (Extended Search)

Laser-Induced Breakdown Spectroscopy System Laser-Induced Breakdown Spectroscopy System Using a Passively Q-Switched Laser Opportunity Research is active on the patent-pending technology, titled "Laser-Induced Breakdown Spectroscopy (LIBS) System Using a Passively Q-Switched Laser." This technology is available for licensing and/or further collaborative research from the U.S. Department of Energy's National Energy Technology Laboratory. Overview Atomic spectroscopy systems such as LIBS are used in many applications where the elemental composition of a solid, liquid or gas sample is desired. In addition, this detection technology has the advantage of providing composition data without sample destruction. In LIBS systems, precise timing and control between the laser and the spectrometer detector are

362

Analysis of Lipid OxidationChapter 6 Analysis of Lipid Oxidation by ESR Spectroscopy  

Science Conference Proceedings (OSTI)

Analysis of Lipid Oxidation Chapter 6 Analysis of Lipid Oxidation by ESR Spectroscopy Methods and Analyses eChapters Methods - Analyses Books Downloadable pdf of Chapter 6 Analysis of Lipid Oxidation by ESR Spectrosco

363

Analysis of Lipid OxidationChapter 5 Analysis of Lipid Oxidation Products by NMR Spectroscopy  

Science Conference Proceedings (OSTI)

Analysis of Lipid Oxidation Chapter 5 Analysis of Lipid Oxidation Products by NMR Spectroscopy Methods and Analyses eChapters Methods - Analyses Books AOCS Press Downloadable pdf of Chapter 5 Analysis of Lipid Oxi

364

Molecular dynamics analysis of PVA-AgnP composites by dielectric spectroscopy  

Science Conference Proceedings (OSTI)

The molecular dynamics of PVA/AgnP composites were studied by dielectric spectroscopy (DS) in the 20-300°C temperature range. Improper water elimination leads to misinterpretation of thermal relaxations in PVA composites in agreement with the previous ...

J. Betzabe González-Campos; Evgen Prokhorov; Isaac C. Sanchez; J. Gabriel Luna-Bárcenas; Alejandro Manzano-Ramírez; Jesús González-Hernández; Yliana López-Castro; Rosa E. del Río

2012-01-01T23:59:59.000Z

365

Proceedings of the Fourteenth International Conference on Time-Resolved Vibrational Spectroscopy (TRVS XIV)  

E-Print Network (OSTI)

Abstracts of presentations made at the Fourteenth International Conference on Time-Resolved Vibrational Spectroscopy (TRVS XIV) held May 9-14, 2009 in Meredith, New Hampshire. TRVS is a series of biennial conferences ...

Tokmakoff, Andrei

2011-08-31T23:59:59.000Z

366

Spectroscopy and external control of optical dynamics in single semiconductor nanocrystals  

E-Print Network (OSTI)

Single molecule spectroscopy has progressed substantially in the past ten years and the accompanying progress in the optical study of single semiconductor nanocrystals has opened a new dimension in our understanding of the ...

Shimizu, Kentaro, 1975-

2002-01-01T23:59:59.000Z

367

Multi-mode two-dimensional infrared spectroscopy of peptides and proteins  

E-Print Network (OSTI)

In this thesis, a methodology for understanding structural stability of proteins through multi-mode two-dimensional infrared (2D IR) spectroscopy is developed. The experimental framework for generation of broadband infrared ...

DeFlores, Lauren P

2008-01-01T23:59:59.000Z

368

Field Testing of Cavity Ring-Down Spectroscopy Analyzers Measuring Carbon Dioxide and Water Vapor  

Science Conference Proceedings (OSTI)

Prevalent methods for making high-accuracy tower-based measurements of the CO2 mixing ratio, notably nondispersive infrared spectroscopy (NDIR), require frequent system calibration and sample drying. Wavelength-scanned cavity ring-down ...

Scott J. Richardson; Natasha L. Miles; Kenneth J. Davis; Eric R. Crosson; Chris W. Rella; Arlyn E. Andrews

2012-03-01T23:59:59.000Z

369

Time-resolved Spectroscopy of Laser-heated Copper Foils | Stanford...  

NLE Websites -- All DOE Office Websites (Extended Search)

Spectroscopy of Laser-heated Copper Foils Tuesday, July 16, 2013 - 11:00am SLAC, Conference Room 137-322 Presented by Kelly Cone, PhD Engineering, Dept. of Applied Science,...

370

Two-photon (vuv and visible) resonant ionization spectroscopy of atoms and molecules  

DOE Green Energy (OSTI)

Two photon spectroscopy of argon, krypton and molecular hydrogen is considered in this paper. Experimental transition energies and two-photon rate constants are given. 4 refs., 1 tab. (LSP)

McCann, M.P.; Chen, C.H.; Payne, M.G.

1987-12-01T23:59:59.000Z

371

FT-IR spectroscopy technology, market evolution and future strategies of Bruker Optics Inc.  

E-Print Network (OSTI)

This thesis explores the technology and market evolution of FT-IR spectroscopy over its nearly forty year history to aid in determining future product design and marketing strategies for an industry-leading firm, Bruker ...

Higdon, Thomas (Thomas Charles)

2010-01-01T23:59:59.000Z

372

Raman spectroscopy study of heat-treated and boron-doped double wall carbon nanotubes  

E-Print Network (OSTI)

We performed Raman spectroscopy experiments on undoped and boron-doped double walled carbon nanotubes (DWNTs) that exhibit the “coalescence inducing mode” as these DWNTs are heat treated to temperatures between 1200 °C ...

Villalpando Paez, Federico

373

Quantum chemistry for spectroscopy : a tale of three spins (S = 0, 1/2, and 1)  

E-Print Network (OSTI)

Three special topics in the field of molecular spectroscopy are investigated using a variety of computational techniques. First, large-amplitude vibrational motions on ground-state singlet (S0) potential energy surfaces ...

Wong, Bryan Matthew, 1979-

2007-01-01T23:59:59.000Z

374

Non-invasive detection of oral cancer using reflectance and fluorescence spectroscopy  

E-Print Network (OSTI)

In vivo reflectance and fluorescence spectra were collected from patients with oral lesions, as well as healthy volunteers, in order to evaluate the potential of spectroscopy to serve as a non-invasive tool for the detection ...

McGee, Sasha Alanda

2008-01-01T23:59:59.000Z

375

Temperature-jump 2D IR spectroscopy to study protein conformational dynamics  

E-Print Network (OSTI)

Temperature-jump (T-jump) two-dimensional infrared spectroscopy (2D IR) is developed, characterized, and applied to the study of protein folding and association. In solution, protein conformational changes span a wide range ...

Jones, Kevin C. (Kevin Chapman)

2012-01-01T23:59:59.000Z

376

Light Shift Measurements of Cold Rubidium Atoms using Raman Pump-Probe Spectroscopy.  

E-Print Network (OSTI)

??We have measured light shifts, also known as the A.C. Stark effect, in cold Rubidium atoms using pump-probe spectroscopy. The measurement was made both for… (more)

Souther, Nathan Jon

2009-01-01T23:59:59.000Z

377

High-sensitivity detection of trace gases using dynamic photoacoustic spectroscopy  

E-Print Network (OSTI)

Lincoln Laboratory of Massachusetts Institute of Technology has developed a technique known as dynamic photoacoustic spectroscopy (DPAS) that could enable remote detection of trace gases via a field-portable laser-based ...

Wynn, Charles M.

378

Measurements of the Vapor Pressure of Supercooled Water Using Infrared Spectroscopy  

Science Conference Proceedings (OSTI)

Measurements are presented of the vapor pressure of supercooled water utilizing infrared spectroscopy, which enables unambiguous verification that the authors’ data correspond to the vapor pressure of liquid water, not a mixture of liquid water ...

Will Cantrell; Eli Ochshorn; Alexander Kostinski; Keith Bozin

2008-09-01T23:59:59.000Z

379

Electrochemical in-situ reaction cell for X-ray scattering, diffraction and spectroscopy  

DOE Green Energy (OSTI)

An electrochemical in-situ reaction cell for hard X-ray experiments with battery electrodes is described. Applications include the small angle scattering, diffraction, and near-edge spectroscopy of lithium manganese oxide electrodes.

Braun, Artur; Granlund, Eric; Cairns, Elton J.

2003-01-27T23:59:59.000Z

380

Fusion-evaporation reactions: a tool for gamma-ray spectroscopy on light nuclei  

SciTech Connect

We have studied the weak-decay channels of fusion/evaporation in light projectile/light target systems in order to provide reliable predictions for gamma-spectroscopy experiments.

Gibelin, J.; Phair, L.; Wiedeking, M.; Clark, R. M.; Cromaz, M.; Deleplanque, M.-A.; Fallon, P.; Lee, I.-Y.; Macchiavelli, A. O.; McMahan, M. A. [Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Bernstein, L. A.; Burke, J. T.; Bleuel, D. L.; Lesher, S. R. [Lawrence Livermore National Laboratory, Livermore, CA 94550 (United States); Hatarik, R. [Rutgers University, New Brunswick, NJ 08854 (United States); Lake, P. T.; Rodriguez-Vieitez, E.; Moretto, L. G. [Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); University of California, Berkeley CA 94720 (United States); Lyles, B. F. [Lawrence Livermore National Laboratory, Livermore, CA 94550 (United States); University of California, Berkeley CA 94720 (United States)

2008-04-17T23:59:59.000Z

Note: This page contains sample records for the topic "angle-resolved photoemission spectroscopy" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


381

Thermal decomposition of CH{sub 3}CHO studied by matrix infrared spectroscopy and photoionization mass spectroscopy  

Science Conference Proceedings (OSTI)

A heated SiC microtubular reactor has been used to decompose acetaldehyde and its isotopomers (CH{sub 3}CDO, CD{sub 3}CHO, and CD{sub 3}CDO). The pyrolysis experiments are carried out by passing a dilute mixture of acetaldehyde (roughly 0.1%-1%) entrained in a stream of a buffer gas (either He or Ar) through a heated SiC reactor that is 2-3 cm long and 1 mm in diameter. Typical pressures in the reactor are 50-200 Torr with the SiC tube wall temperature in the range 1200-1900 K. Characteristic residence times in the reactor are 50-200 {mu}s after which the gas mixture emerges as a skimmed molecular beam at a pressure of approximately 10 {mu}Torr. The reactor has been modified so that both pulsed and continuous modes can be studied, and results from both flow regimes are presented. Using various detection methods (Fourier transform infrared spectroscopy and both fixed wavelength and tunable synchrotron radiation photoionization mass spectrometry), a number of products formed at early pyrolysis times (roughly 100-200 {mu}s) are identified: H, H{sub 2}, CH{sub 3}, CO, CH{sub 2}=CHOH, HC{identical_to}CH, H{sub 2}O, and CH{sub 2}=C=O; trace quantities of other species are also observed in some of the experiments. Pyrolysis of rare isotopomers of acetaldehyde produces characteristic isotopic signatures in the reaction products, which offers insight into reaction mechanisms that occur in the reactor. In particular, while the principal unimolecular processes appear to be radical decomposition CH{sub 3}CHO (+M) {yields} CH{sub 3}+ H + CO and isomerization of acetaldehyde to vinyl alcohol, it appears that the CH{sub 2}CO and HCCH are formed (perhaps exclusively) by bimolecular reactions, especially those involving hydrogen atom attacks.

Vasiliou, AnGayle K. [Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309-0215 (United States); National Renewable Energy Laboratory, 1617 Cole Blvd., Golden, Colorado 80401 (United States); Piech, Krzysztof M.; Reed, Beth; Ellison, G. Barney [Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309-0215 (United States); Zhang Xu [Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, California 91109-8099 (United States); Nimlos, Mark R. [National Renewable Energy Laboratory, 1617 Cole Blvd., Golden, Colorado 80401 (United States); Ahmed, Musahid; Golan, Amir; Kostko, Oleg [Chemical Sciences Division, LBNL MS 6R-2100, Berkeley, California 94720 (United States); Osborn, David L. [Combustion Research Facility, Sandia National Laboratories, P.O. Box 969 MS 9055, Livermore, California 94551-0969 (United States); David, Donald E. [Integrated Instrument Design Facility, CIRES, University of Colorado, Boulder, Colorado 80309-0216 (United States); Urness, Kimberly N.; Daily, John W. [Center for Combustion and Environmental Research, Department of Mechanical Engineering, University of Colorado at Boulder, Boulder, Colorado 80309-0427 (United States); Stanton, John F. [Institute for Theoretical Chemistry, Department of Chemistry, University of Texas, Austin, Texas 78712 (United States)

2012-10-28T23:59:59.000Z

382

Raman Spectroscopy and instrumentation for monitoring soil carbon systems.  

SciTech Connect

This work describes developments in the application of Raman scattering and surface-enhanced Raman scattering (SERS) towards the assessment/characterization of carbon in soil. In the past, the nonspecific total carbon mass content of soil samples has generally been determined through mass loss techniques and elemental analysis. However, because of the concern over CO{sub 2} buildup in the atmosphere and its possible role in the ''Greenhouse Effect,'' there is a need for better-defined models of global cycling of carbon. As a means towards this end, there is a need to know more about the structure and functionality of organic materials in soil. Raman spectroscopy may therefore prove to be an exceptional tool in soil carbon analysis. Based on vibrational transitions of irradiated molecules, it provides structural information that is often suitable for sample identification. Furthermore, Raman scattering yields very fine spectral features which offer the potential for multicomponent sample analysis with minimal or no sample pretreatment. Although the intensity of Raman scattering is generally extremely low, the surface-enhanced Raman scattering (SERS) effect can greatly enhance Raman signals (10{sup 6}-10{sup 8} range) through the adsorption of compounds on specially roughened metal surfaces. In our laboratory, we have investigated copper, gold and silver as possible substrate metals in the fabrication of SERS substrates. These substrates have included metal-coated microparticles, metal island films, and redox-roughened metal foils. We have evaluated several laser excitation sources spanning the 515-785 nm range for both Raman and SERS analysis. For this particular study, we have selected fulvic and humic acids as models for establishing the feasibility of using Raman and SERS in soil carbon analysis. Our studies thus far have demonstrated that copper substrates perform best in the SERS detection of humic and fulvic acids, particularly when coupled to electrochemical processes that enhance adsorption of specific compounds. This effect not only yields a stronger signal, but can also impart selectivity in the analysis of complex samples such as soil.

Stokes, D.L.

2003-12-08T23:59:59.000Z

383

SPECTROSCOPY OF ELECTROPRODUCED LIGHT TO MEDIUM MASS LAMBDA HYPERNUCLEI  

SciTech Connect

One of the main tasks of nuclear physics is the study of subatomic particles and their interactions. Nowadays, the fundamental theory of strong interactions is a particularly interesting subject in the field. At the current moment, such a theory is not complete yet. It describes very well the nucleon-nucleon (NN) interactions, which were intensively studied over the last several decades. In our modern, technically advanced world the research gravitates towards the higher energies, reaching deeper inside of the nuclear structure. About sixty years ago the strong interaction was associated with the interaction between nucleons responsible for holding those nucleons together within the nuclear volume. However, with discovery of mesons and strange particles, the picture has changed. The proof of bound states of strange baryons (? particles) with nucleons revealed a broad class of particles participating in the strong interaction, called hadrons. The rich variety of hadron interactions raises an important topic in modern nuclear physics which strives for providing a deep insight into nuclear matter structure. The analysis of the interaction of a strange baryon, called a hyperon, with a nucleon delivers new knowledge of nuclear properties, which were not understood with widely studied nucleon-nucleon interactions. The direct approach for creating an interaction of free hyperons with nucleons in the target is not an easy task in experimental nuclear physics. The relatively short lifetime of free hyperons, which can only be produced as a secondary beam, leads to extremely low statistics. Nowadays, the best known method of hyperon-nucleon interaction study is the formation of hyperons inside of the nucleus. The bound hyperon serves as a probe of nuclear properties of such complex nuclear systems called hypernuclei. Hypernuclear physics itself is a sub-area of nuclear physics, which studies such bound systems. It employs the rich knowledge of the nucleon-nucleon interaction and at the same time performs a generalization of the above mentioned interaction for systems with a third quark flavor – strangeness [1]. Production reactions of ? particles and hypernuclei, as well as spectroscopy and decay modes, provide valuable information on the hyperon interaction. For example, analysis of ? and hypernuclear decay modes gives knowledge of the properties of weak interactions. The study of the energy of ground and excited states exposes the laws of baryon distribution inside of the nucleus. Investigation of ?N and ?? potentials is important for baryon-baryon theories that include strange quarks, e.g. SU(3). These potentials are more short-ranged than the ones for NN and therefore the additional degrees of freedom play an essential role.

Pavlo Baturin

2010-07-13T23:59:59.000Z

384

Ultra-soft x-ray absorption spectroscopy: A bulk and surface probe of materials  

SciTech Connect

Direct comparisons between surface and bulk of diverse materials can be made by simultaneous electron yield (5 nm depth sensitivity) and fluorescence yield (200 nm) ultra soft x-ray absorption spectroscopy measurements utilizing a rapid sample interchange apparatus. For example the orientations of functional groups have been characterized at and near the surface of a series of model polymeric materials highlighting the chemical and molecular sensitivity of ultra soft x-ray absorption spectroscopy. In addition we discuss a bulk sensitive use of fluorescence yield to non destructively study a buried metal polymer interface. A second bulk sensitive example is the use of fluorescence yield oxygen K near edge x-ray spectroscopy as a method to determine the hole state density of high Tc materials.

Fischer, D.A. [National Institute of Standards and Technology, Gaithersburg, MD (United States); Mitchell, G.E.; Dekoven, B.M. [Dow Chemical Co., Midland, MI (United States); Yeh, A.T.; Gland, J.L. [Michigan Univ., Ann Arbor, MI (United States); Moodenbaugh, A.R. [Brookhaven National Lab., Upton, NY (United States)

1993-06-01T23:59:59.000Z

385

Ultra-soft x-ray absorption spectroscopy: A bulk and surface probe of materials  

SciTech Connect

Direct comparisons between surface and bulk of diverse materials can be made by simultaneous electron yield (5 nm depth sensitivity) and fluorescence yield (200 nm) ultra soft x-ray absorption spectroscopy measurements utilizing a rapid sample interchange apparatus. For example the orientations of functional groups have been characterized at and near the surface of a series of model polymeric materials highlighting the chemical and molecular sensitivity of ultra soft x-ray absorption spectroscopy. In addition we discuss a bulk sensitive use of fluorescence yield to non destructively study a buried metal polymer interface. A second bulk sensitive example is the use of fluorescence yield oxygen K near edge x-ray spectroscopy as a method to determine the hole state density of high Tc materials.

Fischer, D.A. (National Institute of Standards and Technology, Gaithersburg, MD (United States)); Mitchell, G.E.; Dekoven, B.M. (Dow Chemical Co., Midland, MI (United States)); Yeh, A.T.; Gland, J.L. (Michigan Univ., Ann Arbor, MI (United States)); Moodenbaugh, A.R. (Brookhaven National Lab., Upton, NY (United States))

1993-01-01T23:59:59.000Z

386

Applications of Admittance Spectroscopy in Photovoltaic Devices Beyond Majority Carrier Trapping Defects: Preprint  

DOE Green Energy (OSTI)

Admittance spectroscopy is commonly used to characterize majority-carrier trapping defects. In today's practical photovoltaic devices, however, a number of other physical mechanisms may contribute to the admittance measurement and interfere with the data interpretation. Such challenges arise due to the violation of basic assumptions of conventional admittance spectroscopy such as single-junction, ohmic contact, highly conductive absorbers, and measurement in reverse bias. We exploit such violations to devise admittance spectroscopy-based methods for studying the respective origins of 'interference': majority-carrier mobility, non-ohmic contact potential barrier, minority-carrier inversion at hetero-interface, and minority-carrier lifetime in a device environment. These methods are applied to a variety of photovoltaic technologies: CdTe, Cu(In,Ga)Se2, Si HIT cells, and organic photovoltaic materials.

Li, J. V.; Crandall, R. S.; Repins, I. L.; Nardes, A. M.; Levi, D. H.; Sulima, O.

2011-07-01T23:59:59.000Z

387

Ultra-sensitive high-precision spectroscopy of a fast molecular ion beam  

Science Conference Proceedings (OSTI)

Direct spectroscopy of a fast molecular ion beam offers many advantages over competing techniques, including the generality of the approach to any molecular ion, the complete elimination of spectral confusion due to neutral molecules, and the mass identification of individual spectral lines. The major challenge is the intrinsic weakness of absorption or dispersion signals resulting from the relatively low number density of ions in the beam. Direct spectroscopy of an ion beam was pioneered by Saykally and co-workers in the late 1980s, but has not been attempted since that time. Here, we present the design and construction of an ion beam spectrometer with several improvements over the Saykally design. The ion beam and its characterization have been improved by adopting recent advances in electrostatic optics, along with a time-of-flight mass spectrometer that can be used simultaneously with optical spectroscopy. As a proof of concept, a noise-immune cavity-enhanced optical heterodyne molecular spectroscopy (NICE-OHMS) setup with a noise equivalent absorption of {approx}2 x 10{sup -11} cm{sup -1} Hz{sup -1/2} has been used to observe several transitions of the Meinel 1-0 band of N{sub 2}{sup +} with linewidths of {approx}120 MHz. An optical frequency comb has been used for absolute frequency calibration of transition frequencies to within {approx}8 MHz. This work represents the first direct spectroscopy of an electronic transition in an ion beam, and also represents a major step toward the development of routine infrared spectroscopy of rotationally cooled molecular ions.

Mills, Andrew A.; Siller, Brian M.; Porambo, Michael W.; Perera, Manori; Kreckel, Holger [Department of Chemistry, University of Illinois, Urbana, Illinois 61801 (United States); McCall, Benjamin J. [Department of Chemistry, University of Illinois, Urbana, Illinois 61801 (United States); Departments of Physics and Astronomy, University of Illinois, Urbana, Illinois 61801 (United States)

2011-12-14T23:59:59.000Z

388

Electron heated target temperature measurements in petawatt laser experiments based on extreme ultraviolet imaging and spectroscopy  

Science Conference Proceedings (OSTI)

Three independent methods (extreme ultraviolet spectroscopy, imaging at 68 and 256 eV) have been used to measure planar target rear surface plasma temperature due to heating by hot electrons. The hot electrons are produced by ultraintense laser-plasma interactions using the 150 J, 0.5 ps Titan laser. Soft x-ray spectroscopy in the 50-400 eV region and imaging at the 68 and 256 eV photon energies give a planar deuterated carbon target rear surface pre-expansion temperature in the 125-150 eV range, with the rear plasma plume averaging a temperature approximately 74 eV.

Ma, T. [Department of Mechanical and Aerospace Engineering, University of California-San Diego, 9500 Gilman Drive, La Jolla, California 92093-0417 (United States); Lawrence Livermore National Laboratory, 7000 East Ave., Livermore, California 94550 (United States); Beg, F. N. [Department of Mechanical and Aerospace Engineering, University of California-San Diego, 9500 Gilman Drive, La Jolla, California 92093-0417 (United States); MacPhee, A. G.; Chung, H.-K.; Key, M. H.; Mackinnon, A. J.; Patel, P. K.; Hatchett, S. [Lawrence Livermore National Laboratory, 7000 East Ave., Livermore, California 94550 (United States); Akli, K. U.; Stephens, R. B. [General Atomics, San Diego, California 92186 (United States); Chen, C. D. [Plasma Science Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Freeman, R. R.; Link, A.; Offermann, D. T.; Ovchinnikov, V.; Van Woerkom, L. D. [College of Mathematical and Physical Sciences, The Ohio State University, 425 Stillman Hall, Columbus, Ohio 43210-1123 (United States)

2008-10-15T23:59:59.000Z

389

Photo-degradation of Lexan polycarbonate studied using positron lifetime spectroscopy  

SciTech Connect

The free volume properties of pristine and UV irradiated Lexan polycarbonate have been investigated using Positron Lifetime Spectroscopy (PLS). The decrease in o-Ps life time and free volume size of irradiated sample is attributed to free volume modification and formation of more stable free radicals. These free radicals are formed due to the breakage of C-O bonds in Lexan polycarbonate after irradiation. This is also supported by the decrease in the intensity of C-O bond after exposure to UV-radiation as studied from Fourier Transform Infrared (FTIR) spectroscopy and it also shows that benzene ring does not undergo any changes after irradiation.

Hareesh, K.; Sanjeev, Ganesh [Microtron Centre, Department of Physics, Mangalore University, Mangalagangotri-574199 (India); Pandey, A. K. [Radiochemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai-400085 (India); Meghala, D.; Ranganathaiah, C. [Department of Studies in Physics, University of Mysore, Manasagangotri-570006 (India)

2013-02-05T23:59:59.000Z

390

Terahertz Time-Domain Spectroscopy Study of Silica Aerogels and Adsorbed Molecular Jiangquan Zhang and D. Grischkowsky*  

E-Print Network (OSTI)

Terahertz Time-Domain Spectroscopy Study of Silica Aerogels and Adsorbed Molecular Vapors Jiangquan time-domain spectroscopy (THz-TDS) study of hydrophobic and hydrophilic silica aerogels, and the adsorption of several molecular vapors in the hydrophilic silica aerogel. The hydrophobic and hydrophilic

Oklahoma State University

391

Electron energy-loss spectroscopy of boron-doped layers in amorphous thin film silicon solar cells  

E-Print Network (OSTI)

Electron energy-loss spectroscopy of boron-doped layers in amorphous thin film silicon solar cells. de Bariloche, Argentina 3 ECN Solar Energy, High Tech Campus, Building 5, 5656 AE Eindhoven energy-loss spectroscopy (EELS) is used to study p-doped layers in n-i-p amorphous thin film Si solar

Dunin-Borkowski, Rafal E.

392

In situ Raman spectroscopy of lanthanum-strontium-cobaltite thin films  

E-Print Network (OSTI)

Raman spectroscopy is used to probe the structural change of Lanthanum Strontium Cobaltite (La1.xSrxCoO 3 -8) thin films across change in composition (0%-60% strontium) and temperature (30*C-520°C). Raman shift peaks were ...

Breucop, Justin Daniel

2012-01-01T23:59:59.000Z

393

X-Ray Absorption Spectroscopy of Transition Metal-Magnesium Hydride Thin  

NLE Websites -- All DOE Office Websites (Extended Search)

X-Ray Absorption Spectroscopy of Transition Metal-Magnesium Hydride Thin X-Ray Absorption Spectroscopy of Transition Metal-Magnesium Hydride Thin Films Title X-Ray Absorption Spectroscopy of Transition Metal-Magnesium Hydride Thin Films Publication Type Journal Article LBNL Report Number LBNL-50574 Year of Publication 2002 Authors Richardson, Thomas J., Baker Farangis, Jonathan L. Slack, Ponnusamy Nachimuthu, Rupert C. C. Perera, Nobumichi Tamura, and Michael D. Rubin Journal Journal of Alloys and Compounds Volume 356-357 Start Page 204 Pagination 204-207 Date Published 08/2003 Keywords A. hydrogen storage materials, NEXAFS, thin film s; C. EXAFS, x-ray diffraction Abstract Mixed metal thin films containing magnesium and a first-row transition element exhibit very large changes in both reflectance and transmittance on exposure to hydrogen gas. Changes in electronic structure and coordination of the magnesium and transition metal atoms during hydrogen absorption were studied using dynamic in situ transmission mode X-ray absorption spectroscopy. Mg K-edge and Ni, Co, and Ti L-edge spectra reflect both reversible and irreversible changes in the metal environments. A significant shift in the nickel L absorption edge shows it to be an active participant in hydride formation. The effect on cobalt and titanium is much less dramatic, suggesting that these metals act primarily as catalysts for formation of magnesium hydride.

394

Developments in enzyme immobilization and near-infrared Raman spectroscopy with downstream renewable energy applications  

DOE Green Energy (OSTI)

This dissertation focuses on techniques for (1) increasing ethanol yields from saccharification and fermentation of cellulose using immobilized cellulase, and (2) the characterization and classification of lignocellulosic feedstocks, and quantification of useful parameters such as the syringyl/guaiacyl (S/G) lignin monomer content using 1064 nm dispersive multichannel Raman spectroscopy and chemometrics.

Lupoi, Jason [Ames Laboratory

2012-08-27T23:59:59.000Z

395

Control of Chlorine inductively coupled plasma using optical-emission spectroscopy  

Science Conference Proceedings (OSTI)

Magneto-resistive random access memory (MRAM) technology is recognized as one of the next key advances in computer memory. To create MRAM, various metals are successively laid down by sputtering to create stacks, which are then etched into suitable patterns. ... Keywords: ICP, MRAM, OES, chlorine, dry etching, inductively coupled plasma, online control, optical-emission spectroscopy, plasma-induced damage

R. B. Young; T. L. Scott; K. A. Prisbrey

2002-10-01T23:59:59.000Z

396

Investigation of organometallic reaction mechanisms with one and two dimensional vibrational spectroscopy  

Science Conference Proceedings (OSTI)

One and two dimensional time-resolved vibrational spectroscopy has been used to investigate the elementary reactions of several prototypical organometallic complexes in room temperature solution. The electron transfer and ligand substitution reactions of photogenerated 17-electron organometallic radicals CpW(CO){sub 3} and CpFe(CO){sub 2} have been examined with one dimensional spectroscopy on the picosecond through microsecond time-scales, revealing the importance of caging effects and odd-electron intermediates in these reactions. Similarly, an investigation of the photophysics of the simple Fischer carbene complex Cr(CO){sub 5}[CMe(OMe)] showed that this class of molecule undergoes an unusual molecular rearrangement on the picosecond time-scale, briefly forming a metal-ketene complex. Although time-resolved spectroscopy has long been used for these types of photoinitiated reactions, the advent of two dimensional vibrational spectroscopy (2D-IR) opens the possibility to examine the ultrafast dynamics of molecules under thermal equilibrium conditions. Using this method, the picosecond fluxional rearrangements of the model metal carbonyl Fe(CO){sub 5} have been examined, revealing the mechanism, time-scale, and transition state of the fluxional reaction. The success of this experiment demonstrates that 2D-IR is a powerful technique to examine the thermally-driven, ultrafast rearrangements of organometallic molecules in solution.

Cahoon, James Francis

2008-12-16T23:59:59.000Z

397

Charged-particle spectroscopy for diagnosing shock R and strength in NIF implosions  

E-Print Network (OSTI)

Charged-particle spectroscopy for diagnosing shock R and strength in NIF implosions A. B. Zylstra shock R and strength in NIF implosionsa) A. B. Zylstra,1,b) J. A. Frenje,1 F. H. Séguin,1 M. J to the National Ignition Facility (NIF) as a National Ignition Campaign diagnostic. The WRF measures the spectrum

398

Backstreaming of a perfluorinated polyether pump oil—an x?ray photoelectron spectroscopy study  

Science Conference Proceedings (OSTI)

The backstreaming of a perfluorinated polyether mechanical pump oil was determined by using x?ray photoelectron spectroscopy to measure oil content on silicon wafer surfaces. Backstreaming test pressures ranged from 0.4 mTorr to 100 mTorr. Backstreaming was identified at most test pressures even though perfluorinated polyether pump oils have low vapor pressures. Overall

Robert Sherman; John Vossen

1990-01-01T23:59:59.000Z

399

Impedance Spectroscopy Failure Diagnosis of a DFIG-Based Wind Turbine  

E-Print Network (OSTI)

Impedance Spectroscopy Failure Diagnosis of a DFIG-Based Wind Turbine Mohamed Becherif, Assia Henni the failure or the malfunction of the doubly-fed induction generator (DFIG). The diagnosis method is based. This first attempt for using this method to the diagnosis of the DFIG provides good results for the detection

Brest, Université de

400

Performance evaluation of fiber optic probes for tissue lifetime fluorescence spectroscopy  

E-Print Network (OSTI)

reflected light. Our findings can be applied towards optimization of fiber-optic probe designs Angeles, CA 90028. ABSTRACT The design of fiber-optic probes plays an important role in optical spectroscopic studies, including fluorescence spectroscopy of biological tissues. It can affect the light

Jones, Linda R.

Note: This page contains sample records for the topic "angle-resolved photoemission spectroscopy" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


401

A 2D nanosphere array for atomic spectroscopy M. Romanelli(1)  

E-Print Network (OSTI)

A 2D nanosphere array for atomic spectroscopy M. Romanelli(1) , I. Maurin, P. Todorov(2) , Chia boulevard, 1784 Sofia, Bulgaria (3) permanent address: National Central University, Jung-Li City, Taoyuan medium, such as a photonic crystal, with an atomic gas. Here, we discuss the first step of this program

Paris-Sud XI, Université de

402

A Preponderance of Elastic Properties of Alpha Plutonium Measured Via Resonant Ultrasound Spectroscopy  

Science Conference Proceedings (OSTI)

Samples of {alpha} plutonium were fabricated at the Los Alamos National Laboratory's Plutonium Facility. Cylindrical samples were machined from cast pucks. Precision immersion density and resonant ultrasound spectroscopy (RUS) measurements were completed on 27 new samples, yielding elastic moduli measurements. Mechanical tests were performed in compression yielding stress-strain curves as a function of rate, temperature and phase.

Saleh, Tarik A. [Los Alamos National Laboratory; Farrow, Adam M. [Los Alamos National Laboratory; Freibert, Franz J. [Los Alamos National Laboratory

2012-06-06T23:59:59.000Z

403

Layer-by-Layer Characterization of a Model Biofuel Cell Anode by (in Situ) Vibrational Spectroscopy  

E-Print Network (OSTI)

Layer-by-Layer Characterization of a Model Biofuel Cell Anode by (in Situ) Vibrational Spectroscopy during the construction of a model biofuel cell anode. The model anode was a layered structure formedDH to the CB layer confirmed successful enzyme immobilization. 1. Introduction Biofuel cells use microorganisms

Brolo, Alexandre G.

404

Development of phonon-polarization THz spectroscopy, and the investigation of relaxor ferroelectrics  

E-Print Network (OSTI)

This thesis develops phonon-polariton based THz spectroscopy and uses this technique to make the first THz frequency dielectric measurements of a relaxor ferroelectric crystal, in particular KTao0.982Nb0.018O3 (KTN 1.8). ...

Paxton, Benjamin John

2006-01-01T23:59:59.000Z

405

SAFIRE-A: Spectroscopy of the Atmosphere Using Far-Infrared Emission/Airborne  

Science Conference Proceedings (OSTI)

A new instrument named SAFIRE-A (Spectroscopy of the Atmosphere using Far-Infrared Emission/Airborne), which can operate on high-altitude platforms, has been developed for the study of the atmospheric composition through limb-scanning emission ...

Bruno Carli; Peter A. R. Ade; Ugo Cortesi; Paul Dickinson; Michele Epifani; Fred C. Gannaway; Alessandro Gignoli; Corneli Keim; Clare Lee; Claude Meny; Jean Leotin; Francesco Mencaraglia; Alexander G. Murray; Ira G. Nolt; Marco Ridolfi

1999-10-01T23:59:59.000Z

406

Spectroscopy of low energy solar neutrinos by MOON -Mo Observatory Of Neutrinos-  

E-Print Network (OSTI)

Spectroscopy of low energy solar neutrinos by MOON -Mo Observatory Of Neutrinos- R. Hazamaa , P Be solar 's. The present status of MOON for the low energy solar experiment is briefly discussed the pp solar flux with good accuracy. 1. INTRODUCTION Realtime studies of the high-energy component of 8

Washington at Seattle, University of

407

Coherent anti-stokes Raman spectroscopy system for point temperature and major species concentration measurement  

DOE Green Energy (OSTI)

The Coherent anti-Stokes Raman Spectroscopy system (CARS) has been developed as a laser-based, advanced, combustion-diagnostic technique to measure temperature and major species concentration. Principles of operation, description of the system and its capabilities, and operational details of this instrument are presented in this report.

Singh, J.P.; Yueh, Fang-Yu

1993-10-01T23:59:59.000Z

408

Space charge spectroscopy of integrated quantum well infrared photodetectorlight emitting diode  

E-Print Network (OSTI)

Space charge spectroscopy of integrated quantum well infrared photodetector±light emitting diode M ± light emitting diode (QWIP-LED). Quasistatic capacitance±voltage (C±V ) characteristics under reverse.V. All rights reserved. Keywords: Quantum-well infrared photodetector; Light-emitting diode; Space charge

Matsik, Steven G.

409

Exciton spectroscopy on single CdSe/ZnSe quantum dot photodiodes  

Science Conference Proceedings (OSTI)

We have investigated the properties of neutral and charged excitons in single CdSe/ZnSe QD photodiodes by @m-photoluminescence spectroscopy. By applying a bias voltage, we have been able to control the number of electrons in a single QD by shifting the ... Keywords: CdSe quantum dots, Photodiode, Stark effect

S. Michaelis de Vasconcellos; A. Pawlis; C. Arens; M. Panfilova; A. Zrenner; D. Schikora; K. Lischka

2009-02-01T23:59:59.000Z

410

Hollow Core Fiber Optics for Mid-Wave and Long-Wave Infrared Spectroscopy  

E-Print Network (OSTI)

Hollow Core Fiber Optics for Mid-Wave and Long-Wave Infrared Spectroscopy Jason M. Kriesel and testing of hollow core glass waveguides (i.e., fiber optics) for use in Mid-Wave Infrared (MWIR) and Long related applications, and fiber optics are a key enabling technology needed to improve the utility

411

Secondary ion coincidence in highly charged ion based secondary ion mass spectroscopy for process characterization  

SciTech Connect

Coincidence counting in highly charged ion based secondary ion mass spectroscopy has been applied to the characterization of selective tungsten deposition via disilane reduction of tungsten hexafluoride on a patterned SiO{sub 2}/Si wafer. The high secondary ion yield and the secondary ion emission from a small area produced by highly charged ions make the coincidence technique very powerful.

Hamza, A.V.; Schenkel, T.; Barnes, A.V.; Schneider, D.H. [Lawrence Livermore National Laboratory, University of California, Livermore, California, 94551 (United States)] [Lawrence Livermore National Laboratory, University of California, Livermore, California, 94551 (United States)

1999-01-01T23:59:59.000Z

412

Nuclear quadrupole resonance of an electronically excited state from high-resolution hole-burning spectroscopy  

E-Print Network (OSTI)

Nuclear quadrupole resonance of an electronically excited state from high-resolution hole-burning 2003; published 5 May 2003 Hole-burning spectroscopy can eliminate inhomogeneous broadening and thereby, the homogeneous linewidth is often small compared to the splittings due to nuclear-spin interactions. Hole-burning

Suter, Dieter

413

Single-Scan NMR Spectroscopy at Arbitrary Dimensions Yoav Shrot and Lucio Frydman*  

E-Print Network (OSTI)

Single-Scan NMR Spectroscopy at Arbitrary Dimensions Yoav Shrot and Lucio Frydman* Contribution resonance (NMR) provides one of the foremost analytical tools available to elucidate the structure a parametric incrementation of their values throughout independent experiments. Two-dimensional (2D) NMR

Frydman, Lucio

414

A Microcoil NMR Probe for Coupling Microscale HPLC with On-Line NMR Spectroscopy  

E-Print Network (OSTI)

A Microcoil NMR Probe for Coupling Microscale HPLC with On-Line NMR Spectroscopy Raju Subramanian, Urbana, Illinois 61801 An HPLC NMR system is presented that integrates a commercial microbore HPLC system using a 0.5-mm column with a 500-MHz proton NMR spectrometer using a custom NMR probe with an observe

Andrews, Anne M.

415

Polarization Resolved Single Dot Spectroscopy of (211)B InAs Quantum Dots  

Science Conference Proceedings (OSTI)

We report on single dot spectroscopy of (211)B InAs quantum dots, grown by molecular beam epitaxy. The dots exhibit sharp emission lines, the origin of which has been identified. Polarization dependent microphotoluminescence spectra confirm fine structure splittings from 20{mu}eV down to the determination limit of our setup (10 {mu}eV).

Germanis, S.; Dialynas, G. E.; Deligeorgis, G.; Hatzopoulos, Z. [Physics Department, University of Crete, P.O. Box 2208, 71003 Heraklion, Crete (Greece); Savvidis, P. G.; Pelekanos, N. T. [Materials Science and Technology Department, University of Crete, P.O. Box 2208, 71003 Heraklion, Crete (Greece)

2011-12-23T23:59:59.000Z

416

Sediment facies classification of a sandy shoreline by means of airborne imaging spectroscopy  

Science Conference Proceedings (OSTI)

Airborne imaging spectroscopy data (AISA Eagle and HyMap) were applied to classify the sediments of a sandy beach in seven sand type classes. On the AISA-Eagle data, several classification strategies were tried out and compared with each other. The best ...

B. Deronde; P. Kempeneers; R. Houhuys; J. -P. Henriet; V. Van Lancker

2008-08-01T23:59:59.000Z

417

Experimental studies of the geometric and electronic structure of chemisorption bonding. Annual Report, Jan. - Dec. 1984  

Science Conference Proceedings (OSTI)

The chemisorption of small molecules on carefully prepared alloy surfaces has been studied using angle-intergrated and angle-resolved photoelectron spectroscopy, as well as with more conventional surface techniques such as thermal desorption, low energy electron diffraction and work function change. The authors have studied the (110) face of the alloy NiAl since it is the lowest index face with equal concentration of Ni and Al atom. Simply stated the objective is to separate or correlate the electronic and geometric factors governing chemisorption on bimetallic systems as a first step towards understanding the selectivity of multi-component catalysts.

Plummer, E.W.; Gustafsson, T.

1985-03-01T23:59:59.000Z

418

Signatures of Non-integer 5f Occupancy in Pu Systems: Magnetic Properties and Photoelectron Spectroscopy Studies  

Science Conference Proceedings (OSTI)

Very diverse Pu compounds exhibit strikingly universal features in their valence-band photoemission (PES) spectra. The conjecture that such features represent the 5f{sup 5} final state multiplet has been corroborated by LDA+Hubbard calculations, meaning that the ground state has a mixed 5f{sup 5}-5f{sup 6} character. Later on, more elaborated DMFT techniques (one crossing approximation, QMC) led to similar conclusions, providing quantitative explanation of such intermediate-valent situation in more details. Analogies in PES spectra of {delta}-Pu and other Pu systems suggest that the situation envisaged for {delta}-Pu is relevant for a large group of Pu compounds. Here we show that the around mean field LDA+U in conjunction with the Hubbard I approximation, which describes well the non-magnetic ground state for {delta}-Pu, captures in reality properties of a large group of Pu (as well as e.g. Am) compounds, reproducing correctly the onset of magnetism and size of magnetic moments. (authors)

Havela, Ladislav [Department of Electronic Structures, Charles University, Ke Karlovu 5, Prague 2, CZ-12116 (Czech Republic); Shick, Alexander [Institute of Physics, Academy of Sciences of the Czech Republic, Prague 8, CZ-18221 (Czech Republic); Gouder, Thomas; Wastin, Franck; Rebizant, Jean [European Commission, Joint Research Centre, Institute for Transuranium Elements, Postfach 2340, Karlsruhe 1, D-76125 (Germany)

2008-07-01T23:59:59.000Z

419

Characterization of Soil Shrink-Swell Potential Using the Texas VNIR Diffuse Reflectance Spectroscopy Library  

E-Print Network (OSTI)

Shrinking and swelling soils cause extensive infrastructure and economic damage worldwide. Shrink-swell soils are of great concern in Texas for two reasons, 1) Texas has the most acreage of shrink-swell soils in the United States, and 2) yearly evapotranspiration rates exceed those of precipitation creating optimal conditions for soil wetting and drying cycles. This study was conducted to determine if visible near infrared diffuse reflectance spectroscopy (VNIR-DRS) can be used to predict the coefficient of linear extensibility (COLE) of soils. If successful, VNIR-DRS would provide a means to rapidly and inexpensively quantify a soil’s shrink-swell potential real-time. Using soils that have been previously analyzed and archived in the Texas Agrilife Research Soil Characterization Laboratory, our objectives were to: 1) predict the coefficient of linear extractability (COLE) using spectroscopy, 2) predict COLE using measurements of total clay and cation exchange capacity (CEC), and 3) compare the two models. A total of 2454 soil samples were scanned to create the Texas spectral library. Of these samples, 1296 had COLE measurements. Seventy percent of the COLE samples were randomly selected to build a calibration model using partial least squares regression. The remaining thirty percent were used to validate the calibration model. The coefficient of determination (R2), root mean square deviation (RMSD), and relative percent difference (RPD) were calculated to assess the prediction models. The COLE prediction using spectroscopy had an R2, RMSD, and RPD of 0.61, 0.028, and 1.6, respectively. Using stepwise regression and backward elimination, we determined that CEC and total clay together were the best predictors of COLE with R2, RMSD, and RPD of 0.82, 0.019, and 2.3, respectively. According to the RPD, using spectroscopy to predict COLE has some predictive value, while using CEC and total clay is more effective and stable. However, spectroscopy data collection is more rapid and has fixed costs.

Hallmark, C.T.; Morgan, C.L.; Hutchison, K.M.

2011-08-04T23:59:59.000Z

420

Detection and Quantitative Analysis of Chemical Species in Hanford Tank Materials Using Raman Spectroscopy Technology: FY94Florida State University Raman Spectroscopy Report  

Science Conference Proceedings (OSTI)

This report provides a summary of work completed in FY-94 by FSU to develop and investigate the feasibility of using Raman spectroscopy with Hanford tank waste materials. Raman performance impacts from sample morphology, including the effects of absorption, particle size, density, color and refractive index, are discussed. An algorithm for relative species concentration measurement from Raman data is presented. An Algorithm for applying Raman to tank waste core screening is presented and discussed. A library of absorption and Raman spectra are presented that support this work.

Reich, F.R.

1997-08-11T23:59:59.000Z

Note: This page contains sample records for the topic "angle-resolved photoemission spectroscopy" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


421

The big and little of fifty years of Moessbauer spectroscopy at Argonne.  

SciTech Connect

Using radioactive materials obtained by chance, a turntable employing gears from Heidelberg's mechanical toy shops, and other minimal equipment available in post World War II Germany, in 1959 Rudolf Moessbauer confirmed his suspicion that his graduate research had yielded ground-breaking results. He published his conclusion: an atomic nucleus in a crystal undergoes negligible recoil when it emits a low energy gamma ray and provides the entire energy to the gamma ray. In the beginning Moessbauer's news might have been dismissed. As Argonne nuclear physicist Gilbert Perlow noted: ''Everybody knew that nuclei were supposed to recoil when emitting gamma rays--people made those measurements every day''. If any such effect existed, why had no one noticed it before? The notion that some nuclei would not recoil was ''completely crazy'', in the words of the eminent University of Illinois condensed matter physicist Frederich Seitz. Intrigued, however, nuclear physicists as well as condensed matter (or solid state) physicists in various locations--but particularly at the Atomic Energy Research Establishment at Harwell in Britain and at Argonne and Los Alamos in the U.S.--found themselves pondering the Moessbauer spectra with its nuclear and solid state properties starting in late 1959. After an exciting year during which Moessbauer's ideas were confirmed and extended, the physics community concluded that Moessbauer was right. Moessbauer won the Nobel Prize for his work in 1961. In the 1960s and 1970s Argonne physicists produced an increasingly clear picture of the properties of matter using the spectroscopy ushered in by Moessbauer. The scale of this traditional Moessbauer spectroscopy, which required a radioactive source and other simple equipment, began quite modestly by Argonne standards. For example Argonne hosted traditional Moessbauer spectroscopy research using mostly existing equipment in the early days and equipment that cost $100,000 by the 1970s alongside work at the $50 million Zero Gradient Synchrotron (ZGS) and the $30 million Experimental Breeder Reactor (EBR) II. Starting in the mid-1990s, Argonne physicists expanded their exploration of the properties of matter by employing a new type of Moessbauer spectroscopy--this time using synchrotron light sources such as Argonne's Advanced Photon Source (APS), which at $1 billion was the most expensive U.S. accelerator project of its time. Traditional Moessbauer spectroscopy looks superficially like prototypical ''Little Science'' and Moessbauer spectroscopy using synchrotrons looks like prototypical ''Big Science''. In addition, the growth from small to larger scale research seems to follow the pattern familiar from high energy physics even though the wide range of science performed using Moessbauer spectroscopy did not include high energy physics. But is the story of Moessbauer spectroscopy really like the tale told by high energy physicists and often echoed by historians? What do U.S. national laboratories, the ''Home'' of Big Science, have to offer small-scale research? And what does the story of the 50-year development of Moessbauer spectroscopy at Argonne tell us about how knowledge is produced at large laboratories? In a recent analysis of the development of relativistic heavy ion science at Lawrence Berkeley Laboratory I questioned whether it was wise for historians to speak in terms of ''Big Science'', pointing out at that Lawrence Berkeley Laboratory hosted large-scale projects at three scales, the grand scale of the Bevatron, the modest scale of the HILAC, and the mezzo scale of the combined machine, the Bevalac. I argue that using the term ''Big Science'', which was coined by participants, leads to a misleading preoccupation with the largest projects and the tendency to see the history of physics as the history of high energy physics. My aim here is to provide an additional corrective to such views as well as further information about the web of connections that allows national laboratory scientists working at a variety of scales to produce both technological and

Westfall, C.

2005-09-20T23:59:59.000Z

422

Electronic structure of delta-doped La:SrTiO{sub 3} layers by hard x-ray photoelectron spectroscopy  

Science Conference Proceedings (OSTI)

We have employed hard x-ray photoemission (HAXPES) to study a delta-doped SrTiO{sub 3} layer that consisted of a 3-nm thickness of La-doped SrTiO{sub 3} with 6% La embedded in a SrTiO{sub 3} film. Results are compared to a thick, uniformily doped La:SrTiO{sub 3} layer. We find no indication of a band offset for the delta-doped layer, but evidence of the presence of Ti{sup 3+} in both the thick sample and the delta-layer, and indications of a density of states increase near the Fermi energy in the delta-doped layer. These results further demonstrate that HAXPES is a powerful tool for the non-destructive investigation of deeply buried doped layers.

Kaiser, A. M. [Department of Physics, University of California, Davis, California 95616 (United States); Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Peter-Gruenberg-Institut PGI-6, Forschungszentrum Juelich, 52425 Juelich (Germany); Gray, A. X. [Department of Physics, University of California, Davis, California 95616 (United States); Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025 (United States); Conti, G.; Fadley, C. S. [Department of Physics, University of California, Davis, California 95616 (United States); Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Jalan, B. [Materials Department, University of California, Santa Barbara, California 93106-5050 (United States); Department of Chemical Engineering and Materials Science, University of Minnesota, Twin Cities, Minnesota 55455 (United States); Kajdos, A. P.; Stemmer, S. [Materials Department, University of California, Santa Barbara, California 93106-5050 (United States); Gloskovskii, A. [Institut fuer Anorganische Chemie und Analytische Chemie, Johannes Gutenberg-Universitaet, 55099 Mainz (Germany); Ueda, S.; Yamashita, Y.; Kobayashi, K. [NIMS Beamline Station at SPring-8, National Institute for Materials Science, Hyogo 679-5148 (Japan); Drube, W. [Deutsches Elektronen-Synchrotron (DESY), Notkestrasse 85, 22607 Hamburg (Germany)

2012-06-25T23:59:59.000Z

423

Control of resonance enhanced multi-photon ionization photoelectron spectroscopy by phase-shaped femtosecond laser pulse  

Science Conference Proceedings (OSTI)

In this paper, we theoretically demonstrate that the (2+1+1) resonance enhanced multi-photon ionization photoelectron spectroscopy in sodium atom can be effectively controlled by shaping femtosecond laser pulse with a {pi} phase step modulation in weak laser field, involving its total photoelectron energy, maximal photoelectron intensity, and spectroscopic bandwidth. Our results show that the total photoelectron energy can be suppressed but not enhanced, the maximal photoelectron intensity can be enhanced and also suppressed, and the photoelectron spectroscopy can be tremendously narrowed. These theoretical results can provide a feasible scheme to achieve the high-resolution photoelectron spectroscopy and study the excited state structure in atomic and molecular systems.

Zhang Shian; Lu Chenhui; Jia Tianqing; Sun Zhenrong [State Key Laboratory of Precision Spectroscopy, and Department of Physics, East China Normal University, Shanghai 200062 (China); Qiu Jianrong [State Key Laboratory of Luminescent Materials and Devices, and Institute of Optical Communication Materials, South China University of Technology, Wushan Road 381, Guangzhou 510640 (China)

2012-11-07T23:59:59.000Z

424

X-RAY ABSORPTION SPECTROSCOPY OF TRANSITION METAL-MAGNESIUM HYDRIDE FILMS  

NLE Websites -- All DOE Office Websites (Extended Search)

Spectroscopy of Transition Metal-Magnesium Spectroscopy of Transition Metal-Magnesium Hydride Thin Films T. J. Richardson a, *, B. Farangis a , J. L. Slack a , P. Nachimuthu b , R. Pereira b , N. Tamura b , and M. Rubin a a Environmental Energy Technologies Division, b Advanced Light Source, Ernest Orlando Lawrence Berkeley National Laboratory Berkeley, California 94720, USA *Corresponding author, E-mail address: tjrichardson@lbl.gov Abstract Mixed metal thin films containing magnesium and a first-row transition element exhibit very large changes in both reflectance and transmittance on exposure to hydrogen gas. Changes in electronic structure and coordination of the magnesium and transition metal atoms during hydrogen absorption were studied using dynamic in situ transmission mode X-ray absorption

425

Characterization of Gas Shales by X-ray Raman Spectroscopy | Stanford  

NLE Websites -- All DOE Office Websites (Extended Search)

Characterization of Gas Shales by X-ray Raman Spectroscopy Characterization of Gas Shales by X-ray Raman Spectroscopy Monday, May 14, 2012 - 3:30pm SSRL Conference Room 137-322 Drew Pomerantz, Schlumberger Unconventional hydrocarbon resources such as gas shale and oil-bearing shale have emerged recently as economically viable sources of energy, dramatically altering America's energy landscape. Despite their importance, the basic chemistry and physics of shales are not understood as well as conventional reservoirs. In particular, shales are unique in that they contain kerogen, a complex organic solid that controls factors such as the amount of hydrocarbon that can be produced from the reservoir and the rate at which the hydrocarbon is produced. The industry's current understanding of the chemical composition of kerogen is limited, preventing detailed

426

Raman Spectroscopy of Lithium Hydride Corrosion: Selection of an Appropriate Excitation Wavelength to Minimize Fluorescence  

DOE Green Energy (OSTI)

The recent interest in a hydrogen-based fuel economy has renewed research into metal hydride chemistry. Many of these compounds react readily with water to release hydrogen gas and form a caustic. Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFT) has been used to study the hydrolysis reaction. The LiOH stretch appears at 3670 cm{sup -1}. Raman spectroscopy is a complementary technique that employs monochromatic excitation (laser) allowing access to the low energy region of the vibrational spectrum (<600 cm{sup -1}). Weak scattering and fluorescence typically prevent Raman from being used for many compounds. The role of Li{sub 2}O in the moisture reaction has not been fully studied for LiH. Li{sub 2}O can be observed by Raman while being hidden in the Infrared spectrum.

Stowe, A. C.; Smyrl, N. R.

2011-05-26T23:59:59.000Z

427

Characterization of Gas Shales by X-ray Raman Spectroscopy | Stanford  

NLE Websites -- All DOE Office Websites (Extended Search)

Characterization of Gas Shales by X-ray Raman Spectroscopy Characterization of Gas Shales by X-ray Raman Spectroscopy Thursday, February 23, 2012 - 10:30am SSRL Third Floor Conference Room 137-322 Drew Pomerantz, Schlumberger Unconventional hydrocarbon resources such as gas shale and oil-bearing shale have emerged recently as economically viable sources of energy, dramatically altering America's energy landscape. Despite their importance, the basic chemistry and physics of shales are not understood as well as conventional reservoirs. In particular, shales are unique in that they contain kerogen, a complex organic solid that controls factors such as the amount of hydrocarbon that can be produced from the reservoir and the rate at which the hydrocarbon is produced. The industry's current understanding of the chemical composition of kerogen is limited, preventing detailed

428

SSRL School on Synchrotron X-ray Spectroscopy Techniques in Environmental  

NLE Websites -- All DOE Office Websites (Extended Search)

Home Home Agenda Location Visitor Information Transportation Tourism & Dining SSRL School on Synchrotron X-ray Spectroscopy Techniques in Environmental and Materials Sciences: Theory and Application June 2-5, 2009 Group photo of the attendees at the SSRL School on X-ray Spectropscopy Techniques in Environmental and Materials Sciences: Theory and Application held June 2-5, 2009 at the Stanford Synchrotron Radiation Lightsource. » View photos from XAS 2009 Overview: Modern synchrotron radiation based X-ray absorption spectroscopy (SR-XAS) techniques offer the ability to probe local molecular scale physical and electronic structures that govern key properties of technological and environmental materials and molecular complexes. The high collimation, intensity, and tunability of SR allow the investigation of a wide range of materials, including thin films and interfaces, nanoparticles, amorphous materials, solutions, hydrated and disordered bacteriogenic minerals, soils, interfaces, and dissolved species.

429

Two-photon spectroscopy of trapped HD$^+$ ions in the Lamb-Dicke regime  

E-Print Network (OSTI)

We study the feasibility of nearly-degenerate two-photon rovibrational spectroscopy in ensembles of trapped, sympathetically cooled hydrogen molecular ions using a resonance-enhanced multiphoton dissociation (REMPD) scheme. Taking advantage of quasi-coincidences in the rovibrational spectrum, the excitation lasers are tuned close to an intermediate level to resonantly enhance two-photon absorption. Realistic simulations of the REMPD signal are obtained using a four-level model that takes into account saturation effects, ion trajectories, laser frequency noise and redistribution of population by blackbody radiation. We show that the use of counterpropagating laser beams enables optical excitation in an effective Lamb-Dicke regime. Sub-Doppler lines having widths in the 100 Hz range can be observed with good signal-to-noise ratio for an optimal choice of laser detunings. Our results indicate the feasibility of molecular spectroscopy at the $10^{-14}$ accuracy level for improved tests of molecular QED, a new det...

Tran, Vu Quang; Douillet, Albane; Koelemeij, Jeroen C J; Hilico, Laurent

2013-01-01T23:59:59.000Z

430

Ferrocyanide safety program: FY 1995 report on Mossbauer spectroscopy tank activities  

Science Conference Proceedings (OSTI)

This report summarizes FY 1995 activities on the Mossbauer Spectroscopy task. The National Aeronautics and Space Administration has developed a miniaturized Mossbauer spectrometer that is small enough to perform elevation scans in the Hanford Site waste tank liquid observation wells. Mossbauer spectroscopy is a sensitive and selective method that can detect and distinguish between different iron-based compounds in many types of chemical environments. Iron is major constituent of ferrocyanide waste and information about its location and composition in the tanks supports interim safe storage of the waste and final resolution of the Ferrocyanide Safety Issue. Results obtained from studies of ferrocyanide waste simulants and those from the first test in a hot cell environment using radioactive tank waste are presented

Riedel, F.R.

1995-10-02T23:59:59.000Z

431

Beta-decay spectroscopy relevant to the r-process nucleosynthesis  

Science Conference Proceedings (OSTI)

A scientific program of beta-decay spectroscopy relevant to r-process nucleosynthesis has been started using high intensity U-beam at the RIBF. The first results of {beta}-decay half-lives of very neutron-rich Kr to Tc nuclides, all of which lie close to the r-process path, suggest a systematic enhancement of the the {beta}-decay rates of the Zr and Nb isotopes around A110 with respect to the predictions of the deformed quasiparticle-random-phase-approximation model (FRDM + QRPA). An impact of the results on the astrophysical r-process is discussed together with the future perspective of the {beta}-decay spectroscopy with the EURICA.

Nishimura, Shunji [RIKEN Nishina Center, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Collaboration: RIBF Decay Collaboration

2012-11-12T23:59:59.000Z

432

Advanced experimental applications for x-ray transmission gratings spectroscopy using a novel grating fabrication method  

Science Conference Proceedings (OSTI)

A novel fabrication method for soft x-ray transmission grating and other optical elements is presented. The method uses focused-ion-beam technology to fabricate high-quality free standing grating bars on transmission electron microscopy grids. High quality transmission gratings are obtained with superb accuracy and versatility. Using these gratings and back-illuminated CCD camera, absolutely calibrated x-ray spectra can be acquired for soft x-ray source diagnostics in the 100-3000 eV spectral range. Double grating combinations of identical or different parameters are easily fabricated, allowing advanced one-shot application of transmission grating spectroscopy. These applications include spectroscopy with different spectral resolutions, bandwidths, dynamic ranges, and may serve for identification of high-order contribution, and spectral calibrations of various x-ray optical elements.

Hurvitz, G.; Ehrlich, Y.; Shpilman, Z.; Levy, I.; Fraenkel, M. [Plasma Physics Department, Applied Physics Division, Soreq NRC, Yavne (Israel); Strum, G. [Solid State Department, Applied Physics Division, Soreq NRC, Yavne (Israel)

2012-08-15T23:59:59.000Z

433

Atomic data for beam-stimulated plasma spectroscopy in fusion plasmas  

SciTech Connect

Injection of high energy atoms into a confined plasma volume is an established diagnostic technique in fusion research. This method strongly depends on the quality of atomic data for charge-exchange recombination spectroscopy (CXRS), motional Stark effect (MSE) and beam-emission spectroscopy (BES). We present some examples of atomic data for CXRS and review the current status of collisional data for parabolic states of hydrogen atoms that are used for accurate MSE modeling. It is shown that the collisional data require knowledge of the excitation density matrix including the off-diagonal matrix elements. The new datasets for transitions between parabolic states are used in an extended collisional-radiative model. The ratios between the {sigma}- and {pi}-components and the beam-emission rate coefficients are calculated in a quasi-steady state approximation. Good agreement with the experimental data from JET is found which points out to strong deviations from the statistical distribution for magnetic sublevels.

Marchuk, O.; Biel, W.; Schlummer, T. [Institute of Energy and Climate Research, Forschungszentrum Juelich, 52425 Juelich (Germany); Ralchenko, Yu. [Quantum Measurement Division, National Institute of Standards and Technology, Gaithersburg, MD 20899-8422 (United States); Schultz, D. R. [Department of Physics, University of North Texas, Denton, TX 76203 (United States); Collaboration: TEXTOR Team

2013-07-11T23:59:59.000Z

434

Microscale X-ray Absorption Spectroscopy on the GSECARS Sector 13 at the APS  

E-Print Network (OSTI)

GeoSoilEnviroCARS (GSECARS) is a national user facility for frontier research in the earth sciences using synchrotrons radiation at the Advanced Photon Source, Argonne National Laboratory. GSECARS provides earth scientists with access to the high-brilliance hard x-rays from this third-generation synchrotrons light source. The research conducted at this facility will advance our knowledge of the composition, structure and properties of earth materials, the processes they control and the processes that produce them. All principal synchrotron-based analytical techniques in demand by earth scientists are being brought to bear on earth science problems: (1) high-pressure/high-temperature crystallography and spectroscopy using the diamond anvil cell; (2) high-pressure/high-temperature crystallography using the large-volume press; (3) powder, single crystal and interface diffraction; (4) x-ray absorption fine structure (XAFS) spectroscopy; (5) x-ray fluorescence microprobe analysis and microspectroscopy; and (6) mic...

Stephen-Sutto

2000-01-01T23:59:59.000Z

435

Characterization of polysilicon films by Raman spectroscopy and transmission electron microscopy: A comparative study  

SciTech Connect

Samples of chemically-vapor-deposited micrometer and sub-micrometer-thick films of polysilicon were analyzed by transmission electron microscopy (TEM) in cross-section and by Raman spectroscopy with illumination at their surface. TEM and Raman spectroscopy both find varying amounts of polycrystalline and amorphous silicon in the wafers. Raman spectra obtained using blue, green and red excitation wavelengths to vary the Raman sampling depth are compared with TEM cross-sections of these films. Films showing crystalline columnar structures in their TEM micrographs have Raman spectra with a band near 497 cm{sup {minus}1} in addition to the dominant polycrystalline silicon band (521 cm{sup {minus}1}). The TEM micrographs of these films have numerous faulted regions and fringes indicative of nanometer-scale silicon structures, which are believed to correspond to the 497cm{sup {minus}1} Raman band.

Tallant, D.R.; Headley, T.J.; Medernach, J.W. [Sandia National Labs., Albuquerque, NM (United States); Geyling, F. [SEMATECH, Austin, TX (United States)

1993-11-12T23:59:59.000Z

436

In situ photoelectron spectroscopy study of water adsorption on model biomaterial surfaces  

DOE Green Energy (OSTI)

Using in situ photoelectron spectroscopy at near ambient conditions, we compare the interaction of water with four different model biomaterial surfaces: self-assembled thiol monolayers on Au(111) that are functionalized with methyl, hydroxyl, and carboxyl groups, and phosphatidylcholine (POPC) lipid films on Silicon. We show that the interaction of water with biomaterial surfaces is mediated by polar functional groups that interact strongly with water molecules through hydrogen bonding, resulting in adsorption of 0.2-0.3 ML water on the polar thiol films in 700 mTorr water pressure and resulting in characteristic N1s and P2p shifts for the POPC films. Provided that beam damage is carefully controlled, in situ electron spectroscopy can give valuable information about water adsorption which is not accessible under ultra-high vacuum conditions.

Salmeron, Miquel; Ketteler, Guido; Ashby, Paul; Mun, B.S.; Ratera, I.; Bluhm, Hendrik; Kasemo, B.; Salmeron, Miquel

2007-07-10T23:59:59.000Z

437

Strong Equivalence, Lorentz and CPT Violation, Anti-Hydrogen Spectroscopy and Gamma-Ray Burst Polarimetry  

E-Print Network (OSTI)

The strong equivalence principle, local Lorentz invariance and CPT symmetry are fundamental ingredients of the quantum field theories used to describe elementary particle physics. Nevertheless, each may be violated by simple modifications to the dynamics while apparently preserving the essential fundamental structure of quantum field theory itself. In this paper, we analyse the construction of strong equivalence, Lorentz and CPT violating Lagrangians for QED and review and propose some experimental tests in the fields of astrophysical polarimetry and precision atomic spectroscopy. In particular, modifications of the Maxwell action predict a birefringent rotation of the direction of linearly polarised radiation from synchrotron emission which may be studied using radio galaxies or, potentially, gamma-ray bursts. In the Dirac sector, changes in atomic energy levels are predicted which may be probed in precision spectroscopy of hydrogen and anti-hydrogen atoms, notably in the Doppler-free, two-photon $1s-2s$ and $2s-nd (n \\sim 10)$ transitions.

Graham M. Shore

2004-09-13T23:59:59.000Z

438

Multidimensional X-Ray Spectroscopy of Valence and Core Excitations in Cysteine  

E-Print Network (OSTI)

Several nonlinear spectroscopy experiments which employ broadband x-ray pulses to probe the coupling between localized core and delocalized valence excitation are simulated for the amino acid cysteine at the K-edges of oxygen and nitrogen and the K and L-edges of sulfur. We focus on two dimensional (2D) and 3D signals generated by two- and three-pulse stimulated x-ray Raman spectroscopy (SXRS) with frequency-dispersed probe. We show how the four-pulse x-ray signals $\\boldsymbol{k}_\\mathrm{I}=-\\boldsymbol{k}_1+\\boldsymbol{k}_2+\\boldsymbol{k}_3$ and $\\boldsymbol{k}_\\mathrm{II}=\\boldsymbol{k}_1-\\boldsymbol{k}_2+\\boldsymbol{k}_3$ can give new 3D insight into the SXRS signals. The coupling between valence- and core-excited states can be visualized in three dimensional plots, revealing the origin of the polarizability that controls the simpler pump-probe SXRS signals.

Jason D. Biggs; Yu Zhang; Daniel Healion; Shaul Mukamel

2013-03-19T23:59:59.000Z

439

Ambient pressure photoelectron spectroscopy: a new tool for surface science and nanotechnology  

SciTech Connect

Progress in science often follows or parallels the development of new techniques. The optical microscope helped convert medicine and biology from a speculative activity in old times to today's sophisticated scientific disciplines. The telescope changed the study and interpretation of heavens from mythology to science. X-ray diffraction enabled the flourishing of solid state physics and materials science. The technique object of this review, Ambient Pressure Photoelectron Spectroscopy or APPES for short, has also the potential of producing dramatic changes in the study of liquid and solid surfaces, particularly in areas such as atmospheric, environment and catalysis sciences. APPES adds an important missing element to the host of techniques that give fundamental information, i.e., spectroscopy and microscopy, about surfaces in the presence of gases and vapors, as encountered in industrial catalysis and atmospheric environments. APPES brings electron spectroscopy into the realm of techniques that can be used in practical environments. Decades of surface science in ultra high vacuum (UHV) has shown the power of electron spectroscopy in its various manifestations. Their unique property is the extremely short elastic mean free path of electrons as they travel through condensed matter, of the order of a few atomic distances in the energy range from a few eV to a few thousand eV. As a consequence of this the information obtained by analyzing electrons emitted or scattered from a surface refers to the top first few atomic layers, which is what surface science is all about. Low energy electron diffraction (LEED), Auger electron spectroscopy (AES), X-ray photoelectron spectroscopy (XPS), Ultraviolet photoelectron spectroscopy (UPS), and other such techniques have been used for decades and provided some of the most fundamental knowledge about surface crystallography, composition and electronic structure available today. Unfortunately the high interaction cross section of electrons with matter also prevents them from traveling long distances unscattered in gas environments. Above the millibar pressure range this distance is reduced to less that a millimeter, effectively preventing its use in the most relevant environments, usually between millibars and atmospheric pressures. There is therefore a large gap of several orders of magnitude where information about surfaces is scarce because these powerful electron spectroscopies cannot operate. One characteristic of surfaces in ambient pressure environments is that they are covered by dense layers of molecules, even when their binding energy is weak. Water for example is known to form layers several molecules thick at room temperature in humid environments. Metals readily form oxide films several layers thick in oxygen atmospheres. Dense layers of adsorbed molecules can also be produced in ultra high vacuum, often by the simple and expedient method of cooling the sample to cryogenic temperatures. A large amount of data has been obtained in the past in UHV by surface scientists using this method. While this has provided valuable information it begs the question of whether the structures formed in this manner represent equilibrium structures or metastable ones, kinetically trapped due to high activation energies that cannot be overcome at low temperature. From a thermodynamic point of view is interesting to consider the entropic contribution to the Gibbs free energy, which we can call 'the pressure factor', equal to kT.logP. This factor amounts to a sizeable 0.3 eV difference at room temperature between UHV (<10{sup -8} Pascal) and atmospheric pressures. Such change if free energy can definitely result in changes in surface structure and stability. Entire areas of the phase diagram are out of reach due to the pressure gap. Even when cooling is not necessary, many surface treatments and most chemical reactions necessitate the presence of gases at pressures ranging from millibar to bars. What is the structure and chemical nature of the species formed on the surface in equilibrium with suc

Salmeron, Miquel; Salmeron, Miquel; Schlogl, Robert

2008-03-12T23:59:59.000Z

440

Use of In-Situ Gamma Spectroscopy During Nuclear Power Plant Decommissioning  

Science Conference Proceedings (OSTI)

Due to leakage and other events that may occur during nuclear power plant operations, soil, concrete and bedrock have the potential to become contaminated, and therefore must be characterized to demonstrate that they meet strict regulatory site release limits. This report provides detailed information on the use of portable gamma spectroscopy systems for the characterization and Final Status Survey of soil, concrete and bedrock contaminated with radionuclides at a number of plants undergoing decommission...

2010-12-06T23:59:59.000Z

Note: This page contains sample records for the topic "angle-resolved photoemission spectroscopy" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
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We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


441

Assessment of Phase Conductor Inspection Technologies: Near-Infrared Spectroscopy Development  

Science Conference Proceedings (OSTI)

A feasibility study was completed in 2003 to determine if iron oxide deposits can be identified on the surface of aluminum-conductor steel-reinforced (ACSR) conductors. Results were promising and demonstrated that the presence of steel core corrosion may be identified by a ratio of reflected light intensities at specific wavelengths. Early “Near Infrared Spectroscopy” testing in a semi-controlled environment and in the field revealed many environmental conditions must be ...

2013-12-22T23:59:59.000Z

442

Multivariate Calibration Models for Sorghum Composition using Near-Infrared Spectroscopy  

DOE Green Energy (OSTI)

NREL developed calibration models based on near-infrared (NIR) spectroscopy coupled with multivariate statistics to predict compositional properties relevant to cellulosic biofuels production for a variety of sorghum cultivars. A robust calibration population was developed in an iterative fashion. The quality of models developed using the same sample geometry on two different types of NIR spectrometers and two different sample geometries on the same spectrometer did not vary greatly.

Wolfrum, E.; Payne, C.; Stefaniak, T.; Rooney, W.; Dighe, N.; Bean, B.; Dahlberg, J.

2013-03-01T23:59:59.000Z

443

Chemical analysis of uranium-niobium alloys by wavelength dispersive spectroscopy at the sigma complex  

Science Conference Proceedings (OSTI)

Uranium-niobium alloys play an important role in the nation's nuclear stockpile. It is possible to chemically quantify this alloy at a micron scale by using a technique know as wavelength dispersive spectroscopy. This report documents how this technique was used and how it is possible to reproduce measurements of this type. Discussion regarding the accuracy and precision of the measurements, the development of standards, and the comparison of different ways to model the matrices are all presented.

Papin, Pallas A.

2012-06-01T23:59:59.000Z

444

Cl NMR spectroscopy and molecular dynamics modeling complexation with natural organic matter  

E-Print Network (OSTI)

a core oligosaccharide, which was isolated by gel chromatography. It was studied by chemical methods, NMR-glycero-DD-manno-heptose (Hep), GlcN, ManN, and a 3-O-methyl-2-amino-2,6- dideoxyhexose, later identified as 3-O-Me-QuiN by NMR spectroscopy. COSY, TOCSY, NOESY, 1 H­13 C HSQC, and gHMBC 2D NMR spectra of 1 were recorded and com- pletely

Kalinichev, Andrey G.

445

Gas-Phase Molecular Dynamics: High Resolution Spectroscopy and Collision Dynamics of Transient Species  

SciTech Connect

This research is carried out as part of the Gas-Phase Molecular Dynamics program in the Chemistry Department at Brookhaven National Laboratory. Chemical intermediates in the elementary gas-phase reactions involved in combustion chemistry are investigated by high resolution spectroscopic tools. Production, reaction, and energy transfer processes are investigated by transient, double resonance, polarization and saturation spectroscopies, with an emphasis on technique development and connection with theory, as well as specific molecular properties.

Hall, G.E.

2011-05-31T23:59:59.000Z

446

Gas-Phase Molecular Dynamics: High Resolution Spectroscopy and Collision Dynamics of Transient Species  

SciTech Connect

This research is carried out as part of the Gas-Phase Molecular Dynamics program in the Chemistry Department at Brookhaven National Laboratory. Chemical intermediates in the elementary gas-phase reactions involved in combustion chemistry are investigated by high resolution spectroscopic tools. Production, reaction, and energy transfer processes are investigated by transient, double resonance, polarization and saturation spectroscopies, with an emphasis on technique development and connection with theory, as well as specific molecular properties.

Hall G. E.; Goncharov, V.

2012-05-29T23:59:59.000Z

447

Gas-Phase Molecular Dynamics: High Resolution Spectroscopy and Collision Dynamics of Transient Species  

SciTech Connect

This research is carried out as part of the Gas-Phase Molecular Dynamics program in the Chemistry Department at Brookhaven National Laboratory. High-resolution spectroscopy, augmented by theoretical and computational methods, is used to investigate the structure and collision dynamics of chemical intermediates in the elementary gas-phase reactions involved in combustion chemistry. Applications and methods development are equally important experimental components of this work.

Hall,G.E.; Sears, T.J.

2009-04-03T23:59:59.000Z

448

Integral field spectroscopy of protoplanetary disks in Orion with VLT FLAMES  

E-Print Network (OSTI)

We discuss integral field spectroscopy of proplyds in M42 using the FLAMES Argus unit and report the first detection of recombination lines of C II and O II from the archetypical Laques-Vidal-2 object. These lines can provide important new diagnostics of the physical conditions in proplyds. We also draw attention to the future capabilities of the MUSE spectrograph in relation to similar studies.

Y. G. Tsamis; J. R. Walsh; D. Péquignot

2008-04-07T23:59:59.000Z

449

Statistical Methods Applied to Gamma-ray Spectroscopy Algorithms in Nuclear Security Missions  

SciTech Connect

In a wide range of nuclear security missions, gamma-ray spectroscopy is a critical research and development priority. One particularly relevant challenge is the interdiction of special nuclear material for which gamma-ray spectroscopy supports the goals of detecting and identifying gamma-ray sources. This manuscript examines the existing set of spectroscopy methods, attempts to categorize them by the statistical methods on which they rely, and identifies methods that have yet to be considered. Our examination shows that current methods effectively estimate the effect of counting uncertainty but in many cases do not address larger sources of decision uncertainty—ones that are significantly more complex. We thus explore the premise that significantly improving algorithm performance requires greater coupling between the problem physics that drives data acquisition and statistical methods that analyze such data. Untapped statistical methods, such as Bayes Modeling Averaging and hierarchical and empirical Bayes methods have the potential to reduce decision uncertainty by more rigorously and comprehensively incorporating all sources of uncertainty. We expect that application of such methods will demonstrate progress in meeting the needs of nuclear security missions by improving on the existing numerical infrastructure for which these analyses have not been conducted.

Fagan, Deborah K.; Robinson, Sean M.; Runkle, Robert C.

2012-10-01T23:59:59.000Z

450

High resolution laser spectroscopy of cesium and rubidium molecules with optically induced coherence  

E-Print Network (OSTI)

This work is devoted to the study of the quantum coherent effects in diatomic molecular systems by using high resolution laser spectroscopy. In particular, we have studied the rubidium diatomic molecular gaseous medium's absorption spectrum with high resolution single mode laser spectroscopy. The derived electronic and rotational vibrational constants were used in the backward Raman amplification experiment of Rb diatomic molecule. Both experimental results and theoretical calculation confirms that there is strong backward directionally dependent radiation. This effect can further be utilized in remote detection of chemical material. In the saturated spectroscopy experiment of the cesium diatomic molecule, long-lived ground state coherence was observed. The coherence would decay at a rate less than the natural life time of the excited states, which indicates great possibility for performing the quantum optics experiments previously performed in atomic systems only. Electromagnetically induced transparency has been observed in many atomic systems for many years, while it has been seldom realized in molecular systems. In our experiment of electromagnetically induced transparency in cesium diatomic molecules, we utilized Ã?Â? energy levels, and observed subnatural linewidth. This is the first time to realize a Ã?Â? type EIT in a molecular ensemble. This experiment will lead to many other experiments of quantum effects in a molecular system, such like magnetic optical rotation, light storage in ensemble of molecules. Magnetically induced chirality in an atomic ensemble is also investigated in my research.

Chen, Hui

2006-08-01T23:59:59.000Z

451

Time-Resolved FT-IR Spectroscopy of CO Hydrogenation over Supported Ru Catalyst at 700K  

E-Print Network (OSTI)

H. In-Situ Spectroscopy of Catalysts 2004, 32-46. Basu, P. ;over Supported Ru Catalyst at 700 K Walter Wasylenko andAl 2 O 3 -supported, Ru catalyst (Aldrich, 5% Ru, Degussa

Wasylenko, Walter; Frei, Heinz

2008-01-01T23:59:59.000Z

452

Spectroscopy of proton-odd transfermium nuclei Ch. Theisen on behalf of the JUROGAM, GREAT and E375  

E-Print Network (OSTI)

.10.Re 1. Introduction Mendelevium (Z=101) and Lawrencium (Z=103) isotopes have been dis- covered nearly isotopes have been studied so far using prompt gamma- ray spectroscopy: the neutron-odd 253No [9

Paris-Sud XI, Université de

453

Lipid Analysis and Lipidomics: New Techniques & ApplicationChapter 16 Investigation of Protein-Lipid Interactions by Vibrational Spectroscopy  

Science Conference Proceedings (OSTI)

Lipid Analysis and Lipidomics: New Techniques & Application Chapter 16 Investigation of Protein-Lipid Interactions by Vibrational Spectroscopy Methods and Analyses eChapters Methods - Analyses Books AOCS Press Downloadable

454

High-Resolution Spectroscopy of Extremely Metal-Poor Stars from SDSS/SEGUE: I. Atmospheric Parameters and Chemical Compositions  

E-Print Network (OSTI)

Chemical compositions are determined based on high-resolution spectroscopy for 137 candidate extremely metal-poor (EMP) stars selected from the Sloan Digital Sky Survey (SDSS) and its first stellar extension, the Sloan ...

Aoki, Wako

455

The Effects of Variations in Buffer Gas Mixing Ratios on Commercial Carbon Dioxide Cavity Ring-Down Spectroscopy Sensors  

Science Conference Proceedings (OSTI)

Primary gas standards, gas chromatography, and frequency-stabilized cavity ring-down spectroscopy measurements have been used to assess the effect of variations in the argon mixing ratio on the CO2 mixing ratios reported by commercial cavity ring-...

D. A. Long; L. Gameson; G.-W. Truong; K. Bielska; A. Cygan; J. T. Hodges; J. R. Whetstone; R. D. van Zee

456

Dynamic behavior of hydration water in calcium-silicate-hydrate gel: A quasielastic neutron scattering spectroscopy investigation  

E-Print Network (OSTI)

The translational dynamics of hydration water confined in calcium-silicate-hydrate (C-S-H) gel was studied by quasielastic neutron scattering spectroscopy in the temperature range from 280 to 230 K. The stretch exponent ...

Li, Hua

457