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Sample records for atomic absorption spectroscopy

  1. Etalon-induced baseline drift and correction in atom flux sensors based on atomic absorption spectroscopy

    SciTech Connect (OSTI)

    Du, Yingge; Chambers, Scott A.

    2014-10-20

    Atom flux sensors based on atomic absorption (AA) spectroscopy are of significant interest in thin film growth as they can provide unobtrusive, element specific real-time flux sensing and control. The ultimate sensitivity and performance of these sensors are strongly affected by baseline drift. Here we demonstrate that an etalon effect resulting from temperature changes in optical viewport housings is a major source of signal instability, which has not been previously considered, and cannot be corrected using existing methods. We show that small temperature variations in the fused silica viewports can introduce intensity modulations of up to 1.5% which in turn significantly deteriorate AA sensor performance. This undesirable effect can be at least partially eliminated by reducing the size of the beam and tilting the incident light beam off the viewport normal.

  2. Etalon-induced Baseline Drift And Correction In Atom Flux Sensors Based On Atomic Absorption Spectroscopy

    SciTech Connect (OSTI)

    Du, Yingge; Chambers, Scott A.

    2014-10-20

    Atom flux sensors based on atomic absorption (AA) spectroscopy are of significant interest in thin film growth as they can provide unobtrusive, element specific, real-time flux sensing and control. The ultimate sensitivity and performance of the sensors are strongly affected by the long-term and short term baseline drift. Here we demonstrate that an etalon effect resulting from temperature changes in optical viewport housings is a major source of signal instability which has not been previously considered or corrected by existing methods. We show that small temperature variations in the fused silica viewports can introduce intensity modulations of up to 1.5%, which in turn significantly deteriorate AA sensor performance. This undesirable effect can be at least partially eliminated by reducing the size of the beam and tilting the incident light beam off the viewport normal.

  3. Atomic structure of machined semiconducting chips: An x-ray absorption spectroscopy study

    SciTech Connect (OSTI)

    Paesler, M.; Sayers, D.

    1988-12-01

    X-ray absorption spectroscopy (XAS) has been used to examine the atomic structure of chips of germanium that were produced by single point diamond machining. It is demonstrated that although the local (nearest neighbor) atomic structure is experimentally quite similar to that of single crystal specimens information from more distant atoms indicates the presence of considerable stress. An outline of the technique is given and the strength of XAS in studying the machining process is demonstrated.

  4. Determination of heavy metals in solid emission and immission samples using atomic absorption spectroscopy

    SciTech Connect (OSTI)

    Fara, M.; Novak, F.

    1995-12-01

    Both flame and electrothermal methods of atomic absorption spectroscopy (AAS) have been applied to the determination of Al, As, Be, Ca, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, TI, Se, V and Zn in emission and emission (deposition) samples decomposed in open PTFE test-tubes by individual fuming-off hydrofluoric, perchloroic and nitric acid. An alternative hydride technique was also used for As and Se determination and Hg was determined using a self-contained AAS analyzer. A graphite platform proved good to overcome non-spectral interferences in AAS-ETA. Methods developed were verified by reference materials (inc. NBS 1633a).

  5. Self-corrected Sensors Based On Atomic Absorption Spectroscopy For Atom Flux Measurements In Molecular Beam Epitaxy

    SciTech Connect (OSTI)

    Du, Yingge; Droubay, Timothy C.; Liyu, Andrey V.; Li, Guosheng; Chambers, Scott A.

    2014-04-24

    A high sensitivity atom flux sensor based on atomic absorption spectroscopy has been designed and implemented to control electron beam evaporators and effusion cells in a molecular beam epitaxy system. Using a high-resolution spectrometer and a two-dimensional charge coupled device (CCD) detector in a double-beam configuration, we employ a non-resonant line or a resonant line with lower absorbance from the same hollow cathode lamp as the reference for nearly perfect background correction and baseline drift removal. This setup also significantly shortens the warm-up time needed compared to other sensor technologies and drastically reduces the noise coming from the surrounding environment. In addition, the high-resolution spectrometer allows the most sensitive resonant line to be isolated and used to provide excellent signal-to-noise ratio.

  6. Self-corrected sensors based on atomic absorption spectroscopy for atom flux measurements in molecular beam epitaxy

    SciTech Connect (OSTI)

    Du, Y. E-mail: scott.chambers@pnnl.gov; Liyu, A. V.; Droubay, T. C.; Chambers, S. A. E-mail: scott.chambers@pnnl.gov; Li, G.

    2014-04-21

    A high sensitivity atom flux sensor based on atomic absorption spectroscopy has been designed and implemented to control electron beam evaporators and effusion cells in a molecular beam epitaxy system. Using a high-resolution spectrometer and a two-dimensional charge coupled device detector in a double-beam configuration, we employ either a non-resonant line or a resonant line with low cross section from the same hollow cathode lamp as the reference for nearly perfect background correction and baseline drift removal. This setup also significantly shortens the warm-up time needed compared to other sensor technologies and drastically reduces the noise coming from the surrounding environment. In addition, the high-resolution spectrometer allows the most sensitive resonant line to be isolated and used to provide excellent signal-to-noise ratio.

  7. Hydrogen atom temperature measured with wavelength-modulated laser absorption spectroscopy in large scale filament arc negative hydrogen ion source

    SciTech Connect (OSTI)

    Nakano, H. Goto, M.; Tsumori, K.; Kisaki, M.; Ikeda, K.; Nagaoka, K.; Osakabe, M.; Takeiri, Y.; Kaneko, O.; Nishiyama, S.; Sasaki, K.

    2015-04-08

    The velocity distribution function of hydrogen atoms is one of the useful parameters to understand particle dynamics from negative hydrogen production to extraction in a negative hydrogen ion source. Hydrogen atom temperature is one of the indicators of the velocity distribution function. To find a feasibility of hydrogen atom temperature measurement in large scale filament arc negative hydrogen ion source for fusion, a model calculation of wavelength-modulated laser absorption spectroscopy of the hydrogen Balmer alpha line was performed. By utilizing a wide range tunable diode laser, we successfully obtained the hydrogen atom temperature of ∼3000 K in the vicinity of the plasma grid electrode. The hydrogen atom temperature increases as well as the arc power, and becomes constant after decreasing with the filling of hydrogen gas pressure.

  8. New Homogeneous Standards by Atomic Layer Deposition for Synchrotron X-ray Fluorescence and Absorption Spectroscopies.

    SciTech Connect (OSTI)

    Butterworth, A.L.; Becker, N.; Gainsforth, Z.; Lanzirotti, A.; Newville, M.; Proslier, T.; Stodolna, J.; Sutton, S.; Tyliszczak, T.; Westphal, A.J.; Zasadzinski, J.

    2012-03-13

    Quantification of synchrotron XRF analyses is typically done through comparisons with measurements on the NIST SRM 1832/1833 thin film standards. Unfortunately, these standards are inhomogeneous on small scales at the tens of percent level. We are synthesizing new homogeneous multilayer standards using the Atomic Layer Deposition technique and characterizing them using multiple analytical methods, including ellipsometry, Rutherford Back Scattering at Evans Analytical, Synchrotron X-ray Fluorescence (SXRF) at Advanced Photon Source (APS) Beamline 13-ID, Synchrotron X-ray Absorption Spectroscopy (XAS) at Advanced Light Source (ALS) Beamlines 11.0.2 and 5.3.2.1 and by electron microscopy techniques. Our motivation for developing much-needed cross-calibration of synchrotron techniques is borne from coordinated analyses of particles captured in the aerogel of the NASA Stardust Interstellar Dust Collector (SIDC). The Stardust Interstellar Dust Preliminary Examination (ISPE) team have characterized three sub-nanogram, {approx}1{micro}m-sized fragments considered as candidates to be the first contemporary interstellar dust ever collected, based on their chemistries and trajectories. The candidates were analyzed in small wedges of aerogel in which they were extracted from the larger collector, using high sensitivity, high spatial resolution >3 keV synchrotron x-ray fluorescence spectroscopy (SXRF) and <2 keV synchrotron x-ray transmission microscopy (STXM) during Stardust ISPE. The ISPE synchrotron techniques have complementary capabilities. Hard X-ray SXRF is sensitive to sub-fg mass of elements Z {ge} 20 (calcium) and has a spatial resolution as low as 90nm. X-ray Diffraction data were collected simultaneously with SXRF data. Soft X-ray STXM at ALS beamline 11.0.2 can detect fg-mass of most elements, including cosmochemically important oxygen, magnesium, aluminum and silicon, which are invisible to SXRF in this application. ALS beamline 11.0.2 has spatial resolution

  9. Soliton absorption spectroscopy

    SciTech Connect (OSTI)

    Kalashnikov, V. L.; Sorokin, E.

    2010-03-15

    We analyze optical soliton propagation in the presence of weak absorption lines with much narrower linewidths as compared to the soliton spectrum width by using a perturbation analysis technique based on an integral representation in the spectral domain. The stable soliton acquires a spectral modulation that follows the associated index of refraction of the absorber. The model can be applied to ordinary soliton propagation and to an absorber inside a passively mode-locked laser. In the latter case, a comparison with water vapor absorption in a femtosecond Cr:ZnSe laser yields a very good agreement with experiment. Compared to the conventional absorption measurements in a cell of the same length, the signal is increased by an order of magnitude. The obtained analytical expressions allow further improvement in the sensitivity and spectroscopic accuracy, which makes soliton absorption spectroscopy a promising measurement technique.

  10. SMB, X-ray Absorption Spectroscopy

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

    Absorption Spectroscopy X-ray Absorption Spectroscopy X-ray absorption spectroscopy (XAS) is a well-established technique for simultaneous local geometric and electronic structure...

  11. A passive measurement of dissociated atom densities in atmospheric pressure air discharge plasmas using vacuum ultraviolet self-absorption spectroscopy

    SciTech Connect (OSTI)

    Laity, George; Fierro, Andrew; Dickens, James; Neuber, Andreas; Frank, Klaus

    2014-03-28

    We demonstrate a method for determining the dissociation degree of atmospheric pressure air discharges by measuring the self-absorption characteristics of vacuum ultraviolet radiation from O and N atoms in the plasma. The atom densities are determined by modeling the amount of radiation trapping present in the discharge, without the use of typical optical absorption diagnostic techniques which require external sources of probing radiation into the experiment. For an 8.0 mm spark discharge between needle electrodes at atmospheric pressure, typical peak O atom densities of 8.5 × 10{sup 17} cm{sup −3} and peak N atom densities of 9.9 × 10{sup 17} cm{sup −3} are observed within the first ∼1.0 mm of plasma near the anode tip by analyzing the OI and NI transitions in the 130.0–132.0 nm band of the vacuum ultraviolet spectrum.

  12. Cavity-Enhanced Transient Absorption Spectroscopy: Ultrafast...

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

    Cavity-Enhanced Transient Absorption Spectroscopy: Ultrafast Spectroscopy goes Ultra-Sensitive Wednesday, November 11, 2015 - 3:00pm SLAC, Redtail Hawk Conference Room 108A...

  13. Direct and quantitative broadband absorptance spectroscopy with...

    Office of Scientific and Technical Information (OSTI)

    Patent: Direct and quantitative broadband absorptance spectroscopy with multilayer ... DOE Contract Number: FG02-02ER45977 Resource Type: Patent Research Org: Massachusetts ...

  14. Combining Feedback Absorption Spectroscopy, Amplified Resonance...

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

    Automotive Emissions Combining Feedback Absorption Spectroscopy, Amplified Resonance and Low Pressure Sampling for the Measurement of Nitrogen-Containing Compounds in Automotive ...

  15. High resolution absorption spectroscopy of exploding wire plasmas...

    Office of Scientific and Technical Information (OSTI)

    Published Article: High resolution absorption spectroscopy of exploding wire plasmas using an x-pinch x-ray source and spherically bent crystal Title: High resolution absorption ...

  16. Relativistic atomic beam spectroscopy II

    SciTech Connect (OSTI)

    1989-12-31

    The negative ion of H is one of the simplest 3-body atomic systems. The techniques we have developed for experimental study of atoms moving near speed of light have been productive. This proposal request continuing support for experimental studies of the H{sup -} system, principally at the 800 MeV linear accelerator (LAMPF) at Los Alamos. Four experiments are currently planned: photodetachment of H{sup -} near threshold in electric field, interaction of relativistic H{sup -} ions with matter, high excitations and double charge escape in H{sup -}, and multiphoton detachment of electrons from H{sup -}.

  17. Monitoring PVD metal vapors using laser absorption spectroscopy

    SciTech Connect (OSTI)

    Braun, D.G.; Anklam, T.M.; Berzins, L.V.; Hagans, K.G.

    1994-04-01

    Laser absorption spectroscopy (LAS) has been used by the Atomic Vapor Laser Isotope Separation (AVLIS) program for over 10 years to monitor the co-vaporization of uranium and iron in its separators. During that time, LAS has proven to be an accurate and reliable method to monitor both the density and composition of the vapor. It has distinct advantages over other rate monitors, in that it is completely non-obtrusive to the vaporization process and its accuracy is unaffected by the duration of the run. Additionally, the LAS diagnostic has been incorporated into a very successful process control system. LAS requires only a line of sight through the vacuum chamber, as all hardware is external to the vessel. The laser is swept in frequency through an absorption line of interest. In the process a baseline is established, and the line integrated density is determined from the absorption profile. The measurement requires no hardware calibration. Through a proper choice of the atomic transition, a wide range of elements and densities have been monitored (e.g. nickel, iron, cerium and gadolinium). A great deal of information about the vapor plume can be obtained from the measured absorption profiles. By monitoring different species at the same location, the composition of the vapor is measured in real time. By measuring the same density at different locations, the spatial profile of the vapor plume is determined. The shape of the absorption profile is used to obtain the flow speed of the vapor. Finally, all of the above information is used evaluate the total vaporization rate.

  18. X-ray transient absorption and picosecond IR spectroscopy of...

    Office of Scientific and Technical Information (OSTI)

    X-ray transient absorption and picosecond IR spectroscopy of fulvalene(tetracarbonyl)diruthenium on photoexcitation Citation Details In-Document Search Title: X-ray transient ...

  19. Transient absorption spectroscopy of laser shocked explosives

    SciTech Connect (OSTI)

    Mcgrane, Shawn D; Dang, Nhan C; Whitley, Von H; Bolome, Cindy A; Moore, D S

    2010-01-01

    Transient absorption spectra from 390-890 nm of laser shocked RDX, PETN, sapphire, and polyvinylnitrate (PVN) at sub-nanosecond time scales are reported. RDX shows a nearly linear increase in absorption with time after shock at {approx}23 GPa. PETN is similar, but with smaller total absorption. A broad visible absorption in sapphire begins nearly immediately upon shock loading but does not build over time. PVN exhibits thin film interference in the absorption spectra along with increased absorption with time. The absorptions in RDX and PETN are suggested to originate in chemical reactions happening on picosecond time scales at these shock stresses, although further diagnostics are required to prove this interpretation.

  20. Laser absorption spectroscopy system for vaporization process characterization and control

    SciTech Connect (OSTI)

    Galkowski, J.; Hagans, K.

    1993-09-07

    In support of the Lawrence Livermore National Laboratory`s (LLNL`s) Uranium Atomic Vapor Laser Isotope Separation (U-AVLIS) Program, a laser atomic absorption spectroscopy (LAS) system has been developed. This multi-laser system is capable of simultaneously measuring the line densities of {sup 238}U ground and metastable states, {sup 235}U ground and metastable states, iron, and ions at up to nine locations within the separator vessel. Supporting enrichment experiments that last over one hundred hours, this laser spectroscopy system is employed to diagnose and optimize separator system performance, control the electron beam vaporizer and metal feed systems, and provide physics data for the validation of computer models. As a tool for spectroscopic research, vapor plume characterization, vapor deposition monitoring, and vaporizer development, LLNL`s LAS laboratory with its six argon-ion-pumped ring dye lasers and recently added Ti:Sapphire and external-cavity diode-lasers has capabilities far beyond the requirements of its primary mission.

  1. Infrared Absorption Spectroscopy and Chemical Kinetics of Free Radicals

    SciTech Connect (OSTI)

    Curl, Robert F; Glass, Graham

    2004-11-01

    This research was directed at the detection, monitoring, and study of the chemical kinetic behavior by infrared absorption spectroscopy of small free radical species thought to be important intermediates in combustion. Work on the reaction of OH with acetaldehyde has been completed and published and work on the reaction of O({sup 1}D) with CH{sub 4} has been completed and submitted for publication. In the course of our investigation of branching ratios of the reactions of O({sup 1}D) with acetaldehyde and methane, we discovered that hot atom chemistry effects are not negligible at the gas pressures (13 Torr) initially used. Branching ratios of the reaction of O({sup 1}D) with CH{sub 4} have been measured at a tenfold higher He flow and fivefold higher pressure.

  2. Perfect electromagnetic absorption at one-atom-thick scale

    SciTech Connect (OSTI)

    Li, Sucheng; Duan, Qian; Li, Shuo; Yin, Qiang; Lu, Weixin; Li, Liang; Hou, Bo; Gu, Bangming; Wen, Weijia

    2015-11-02

    We experimentally demonstrate that perfect electromagnetic absorption can be realized in the one-atom thick graphene. Employing coherent illumination in the waveguide system, the absorbance of the unpatterned graphene monolayer is observed to be greater than 94% over the microwave X-band, 7–13 GHz, and to achieve a full absorption, >99% in experiment, at ∼8.3 GHz. In addition, the absorption characteristic manifests equivalently a wide range of incident angle. The experimental results agree very well with the theoretical calculations. Our work accomplishes the broadband, wide-angle, high-performance absorption in the thinnest material with simple configuration.

  3. Determination of microgram amounts of selenium and tellurium in copper-base alloys by atomic absorption spectrometry

    SciTech Connect (OSTI)

    Bedrossian, M.

    1984-02-01

    Trace amounts of selenium and tellurium in copper-base alloys are determined by atomic absorption spectroscopy. The alloys are dissolved in nitric acid to yield selenious and tellurous acids which are readily reduced to elemental form. Iodide complexes of both selenium and tellurium are extracted simultaneously using a solution of trioctylphosphine oxide and methyl isobutyl ketone. Selenium and tellurium are determined by flame atomic absorption with a sensitivity of 0.0002%. 6 references, 2 tables.

  4. Using laser absorption spectroscopy to monitor composition and physical properties of metal vapors

    SciTech Connect (OSTI)

    Berzins, L.V.

    1993-09-03

    The Atomic Vapor Laser Isotope Separation (AVLIS) program has been using laser absorption spectroscopy to monitor vapor densities for over 15 years. Laser absorption spectroscopy has proven itself to be an accurate and reliable method to monitor both density and composition. During this time the diagnostic has moved from a research tool toward a robust component of a process control system. The hardware used for this diagnostic is discussed elsewhere at this symposium. This paper describes how the laser absorption spectroscopy diagnostic is used as a component of a process control system as well as supplying detailed measurements on vapor densities, composition, flow velocity, internal and kinetic temperatures, and constituent distributions. Examples will be drawn from the uranium AVLIS program. In addition potential applications such as composition control in the production of metal matrix composites or aircraft alloys will be discussed.

  5. Molecular shock response of explosives: electronic absorption spectroscopy

    SciTech Connect (OSTI)

    Mcgrne, Shawn D; Moore, David S; Whitley, Von H; Bolme, Cindy A; Eakins, Daniel E

    2009-01-01

    Electronic absorption spectroscopy in the range 400-800 nm was coupled to ultrafast laser generated shocks to begin addressing the question of the extent to which electronic excitations are involved in shock induced reactions. Data are presented on shocked polymethylmethacrylate (PMMA) thin films and single crystal pentaerythritol tetranitrate (PETN). Shocked PMMA exhibited thin film interference effects from the shock front. Shocked PETN exhibited interference from the shock front as well as broadband increased absorption. Relation to shock initiation hypotheses and the need for time dependent absorption data (future experiments) is briefly discussed.

  6. X-ray absorption spectroscopy study of Gd[superscript 3+]-loaded...

    Office of Scientific and Technical Information (OSTI)

    Journal Article: X-ray absorption spectroscopy study of Gdsuperscript 3+-loaded ultra-short carbon nanotubes Citation Details In-Document Search Title: X-ray absorption ...

  7. Infrared absorption spectroscopy and chemical kinetics of free radicals

    SciTech Connect (OSTI)

    Curl, R.F.; Glass, G.P.

    1993-12-01

    This research is directed at the detection, monitoring, and study of chemical kinetic behavior by infrared absorption spectroscopy of small free radical species thought to be important intermediates in combustion. During the last year, infrared kinetic spectroscopy using excimer laser flash photolysis and color-center laser probing has been employed to study the high resolution spectrum of HCCN, the rate constant of the reaction between ethynyl (C{sub 2}H) radical and H{sub 2} in the temperature region between 295 and 875 K, and the recombination rate of propargyl (CH{sub 2}CCH) at room temperature.

  8. X-ray absorption fine-structure spectroscopy (Book) | SciTech...

    Office of Scientific and Technical Information (OSTI)

    X-ray absorption fine-structure spectroscopy Citation Details In-Document Search Title: X-ray absorption fine-structure spectroscopy Authors: Newville, M. 1 + Show Author ...

  9. Emission and Absorption Spectroscopy of Carbon Arc Plasma during Formation of Carbon Magnetic Encapsulates

    SciTech Connect (OSTI)

    Lange, H.; Labedz, O.; Huczko, A.; Bystrzejewski, M.

    2011-11-29

    Plasma diagnostics of carbon arc discharge under conditions of carbon magnetic encapsulates formation was performed by emission and absorption spectroscopy. Content of C{sub 2} and Fe species, rotational temperatures of excited (d {sup 3} product {sub g}) and non-excited (a {sup 3} product {sub u}) states, and excitation temperatures of a {sup 5}F and a {sup 3}F levels relatively to the a {sup 5}D level of Fe atoms were determined. The results pointed to a non-equilibrium state of carbon arc plasma under prevailing discharge conditions.

  10. Absorption spectroscopy of a laboratory photoionized plasma experiment at Z

    SciTech Connect (OSTI)

    Hall, I. M.; Durmaz, T.; Mancini, R. C.; Bailey, J. E.; Rochau, G. A.; Golovkin, I. E.; MacFarlane, J. J.

    2014-03-15

    The Z facility at the Sandia National Laboratories is the most energetic terrestrial source of X-rays and provides an opportunity to produce photoionized plasmas in a relatively well characterised radiation environment. We use detailed atomic-kinetic and spectral simulations to analyze the absorption spectra of a photoionized neon plasma driven by the x-ray flux from a z-pinch. The broadband x-ray flux both photoionizes and backlights the plasma. In particular, we focus on extracting the charge state distribution of the plasma and the characteristics of the radiation field driving the plasma in order to estimate the ionisation parameter.

  11. Gas cell for in situ soft X-ray transmission-absorption spectroscopy...

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

    cell for in situ soft X-ray transmission-absorption spectroscopy of materials Previous ... Abstract: A simple gas cell design, constructed primarily from commercially available ...

  12. Resonance ionization spectroscopy of zirconium atoms

    SciTech Connect (OSTI)

    Page, R.H.; Dropinski, S.C.; Worden, E.F. Jr.; Stockdale, J.A.D.

    1992-05-01

    We have examined the stepwise-resonant three-photon-ionization spectrum of neutral zirconium atoms using three separately-tunable pulsed visible dye lasers. Lifetimes of even-parity levels (measured with delayed-photoionization technique) range from 10 to 100 nsec. Direct ionization cross sections appear to be less than 10{sup {minus}17} cm{sup 2}; newly-detected autoionizing levels give peak ionization cross sections (inferred from saturation fluences) up to 10{sup {minus}15} cm{sup 2}. Members of Rydberg series converging to the 315 and 1323 cm{sup {minus}1} levels of Zr{sup +} were identified. ``Clumps`` of autoionizing levels are thought to be due to Rydberg-valence mixing.

  13. Low-loss electron energy loss spectroscopy: An atomic-resolution complement to optical spectroscopies and application to graphene

    SciTech Connect (OSTI)

    Kapetanakis, Myron; Zhou, Wu; Oxley, Mark P.; Lee, Jaekwang; Prange, Micah P.; Pennycook, Stephen J.; Idrobo Tapia, Juan Carlos; Pantelides, Sokrates T.

    2015-09-25

    Photon-based spectroscopies have played a central role in exploring the electronic properties of crystalline solids and thin films. They are a powerful tool for probing the electronic properties of nanostructures, but they are limited by lack of spatial resolution. On the other hand, electron-based spectroscopies, e.g., electron energy loss spectroscopy (EELS), are now capable of subangstrom spatial resolution. Core-loss EELS, a spatially resolved analog of x-ray absorption, has been used extensively in the study of inhomogeneous complex systems. In this paper, we demonstrate that low-loss EELS in an aberration-corrected scanning transmission electron microscope, which probes low-energy excitations, combined with a theoretical framework for simulating and analyzing the spectra, is a powerful tool to probe low-energy electron excitations with atomic-scale resolution. The theoretical component of the method combines density functional theory–based calculations of the excitations with dynamical scattering theory for the electron beam. We apply the method to monolayer graphene in order to demonstrate that atomic-scale contrast is inherent in low-loss EELS even in a perfectly periodic structure. The method is a complement to optical spectroscopy as it probes transitions entailing momentum transfer. The theoretical analysis identifies the spatial and orbital origins of excitations, holding the promise of ultimately becoming a powerful probe of the structure and electronic properties of individual point and extended defects in both crystals and inhomogeneous complex nanostructures. The method can be extended to probe magnetic and vibrational properties with atomic resolution.

  14. Low-loss electron energy loss spectroscopy: An atomic-resolution complement to optical spectroscopies and application to graphene

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

    Kapetanakis, Myron; Zhou, Wu; Oxley, Mark P.; Lee, Jaekwang; Prange, Micah P.; Pennycook, Stephen J.; Idrobo Tapia, Juan Carlos; Pantelides, Sokrates T.

    2015-09-25

    Photon-based spectroscopies have played a central role in exploring the electronic properties of crystalline solids and thin films. They are a powerful tool for probing the electronic properties of nanostructures, but they are limited by lack of spatial resolution. On the other hand, electron-based spectroscopies, e.g., electron energy loss spectroscopy (EELS), are now capable of subangstrom spatial resolution. Core-loss EELS, a spatially resolved analog of x-ray absorption, has been used extensively in the study of inhomogeneous complex systems. In this paper, we demonstrate that low-loss EELS in an aberration-corrected scanning transmission electron microscope, which probes low-energy excitations, combined with amore » theoretical framework for simulating and analyzing the spectra, is a powerful tool to probe low-energy electron excitations with atomic-scale resolution. The theoretical component of the method combines density functional theory–based calculations of the excitations with dynamical scattering theory for the electron beam. We apply the method to monolayer graphene in order to demonstrate that atomic-scale contrast is inherent in low-loss EELS even in a perfectly periodic structure. The method is a complement to optical spectroscopy as it probes transitions entailing momentum transfer. The theoretical analysis identifies the spatial and orbital origins of excitations, holding the promise of ultimately becoming a powerful probe of the structure and electronic properties of individual point and extended defects in both crystals and inhomogeneous complex nanostructures. The method can be extended to probe magnetic and vibrational properties with atomic resolution.« less

  15. Infrared Absorption Spectroscopy and Chemical Kinetics of Free Radicals, Final Technical Report

    DOE R&D Accomplishments [OSTI]

    Curl, Robert F.; Glass, Graham P.

    2004-11-01

    This research was directed at the detection, monitoring, and study of the chemical kinetic behavior by infrared absorption spectroscopy of small free radical species thought to be important intermediates in combustion. Work on the reaction of OH with acetaldehyde has been completed and published and work on the reaction of O({sup 1}D) with CH{sub 4} has been completed and submitted for publication. In the course of our investigation of branching ratios of the reactions of O({sup 1}D) with acetaldehyde and methane, we discovered that hot atom chemistry effects are not negligible at the gas pressures (13 Torr) initially used. Branching ratios of the reaction of O({sup 1}D) with CH{sub 4} have been measured at a tenfold higher He flow and fivefold higher pressure.

  16. Correlated Single-Crystal Electronic Absorption Spectroscopy and X-ray Crystallography at NSLS Beamline X26-C

    SciTech Connect (OSTI)

    A Orville; R Buono; M Cowan; A Heroux; G Shea-McCarthy; D Schneider; J Skinner; M Skinner; D Stoner-Ma; R Sweet

    2011-12-31

    The research philosophy and new capabilities installed at NSLS beamline X26-C to support electronic absorption and Raman spectroscopies coupled with X-ray diffraction are reviewed. This beamline is dedicated full time to multidisciplinary studies with goals that include revealing the relationship between the electronic and atomic structures in macromolecules. The beamline instrumentation has been fully integrated such that optical absorption spectra and X-ray diffraction images are interlaced. Therefore, optical changes induced by X-ray exposure can be correlated with X-ray diffraction data collection. The installation of Raman spectroscopy into the beamline is also briefly reviewed. Data are now routinely generated almost simultaneously from three complementary types of experiments from the same sample. The beamline is available now to the NSLS general user population.

  17. In Situ Diffuse Reflectance IR Spectroscopy and X-ray Absorption Spectroscopy for Fast Catalytic Processes

    SciTech Connect (OSTI)

    N Marinkovic; Q Wang; A Frenkel

    2011-12-31

    A new instrument for synchronous in situ investigations of catalytic materials by IR and X-ray absorption spectroscopies was designed and built at the X18A beamline of the National Synchrotron Light Source of Brookhaven National Laboratory. It provides analytical tools for solving structural, electronic and kinetic problems in catalysis science by two complementary methods. Among the features attractive for catalysis research are the broad range of catalytically active elements that can be investigated (starting with Ni and beyond), the wide range of reaction conditions (temperatures up to 873 K, various reactive gases) and time scales (starting from tens of seconds). The results of several representative experiments that illustrate the attractive capabilities of the new set-up are discussed.

  18. Calculation of the spatial resolution in two-photon absorption spectroscopy applied to plasma diagnosis

    SciTech Connect (OSTI)

    Garcia-Lechuga, M.; Fuentes, L. M.; Grützmacher, K.; Pérez, C. Rosa, M. I. de la

    2014-10-07

    We report a detailed characterization of the spatial resolution provided by two-photon absorption spectroscopy suited for plasma diagnosis via the 1S-2S transition of atomic hydrogen for optogalvanic detection and laser induced fluorescence (LIF). A precise knowledge of the spatial resolution is crucial for a correct interpretation of measurements, if the plasma parameters to be analysed undergo strong spatial variations. The present study is based on a novel approach which provides a reliable and realistic determination of the spatial resolution. Measured irradiance distribution of laser beam waists in the overlap volume, provided by a high resolution UV camera, are employed to resolve coupled rate equations accounting for two-photon excitation, fluorescence decay and ionization. The resulting three-dimensional yield distributions reveal in detail the spatial resolution for optogalvanic and LIF detection and related saturation due to depletion. Two-photon absorption profiles broader than the Fourier transform-limited laser bandwidth are also incorporated in the calculations. The approach allows an accurate analysis of the spatial resolution present in recent and future measurements.

  19. Low-dimensional systems investigated by x-ray absorption spectroscopy...

    Office of Scientific and Technical Information (OSTI)

    Title: Low-dimensional systems investigated by x-ray absorption spectroscopy: a selection of 2D, 1D and 0D cases Authors: Mino, Lorenzo ; Agostini, Giovanni ; Borfecchia, Elisa ; ...

  20. Femtosecond X-ray Absorption Spectroscopy at a Hard X-ray Free...

    Office of Scientific and Technical Information (OSTI)

    Femtosecond X-ray Absorption Spectroscopy at a Hard X-ray Free Electron Laser: Application to Spin Crossover Dynamics Citation Details In-Document Search Title: Femtosecond X-ray...

  1. Americium characterization by X-ray fluorescence and absorption spectroscopy in plutonium uranium mixed oxide

    SciTech Connect (OSTI)

    Degueldre, Claude Cozzo, Cedric; Martin, Matthias; Grolimund, Daniel; Mieszczynski, Cyprian

    2013-06-01

    Plutonium uranium mixed oxide (MOX) fuels are currently used in nuclear reactors. The actinides in these fuels need to be analyzed after irradiation for assessing their behaviour with regard to their environment and the coolant. In this work the study of the atomic structure and next-neighbour environment of Am in the (Pu,U)O? lattice in an irradiated (60 MW d kg?) MOX sample was performed employing micro-X-ray fluorescence (-XRF) and micro-X-ray absorption fine structure (-XAFS) spectroscopy. The chemical bonds, valences and stoichiometry of Am (~0.66 wt%) are determined from the experimental data gained for the irradiated fuel material examined in its peripheral zone (rim) of the fuel. In the irradiated sample Am builds up as Am? species within an [AmO?]? coordination environment (e.g. >90%) and no (<10%) Am(IV) or (V) can be detected in the rim zone. The occurrence of americium dioxide is avoided by the redox buffering activity of the uranium dioxide matrix. - Graphical abstract: Americium LIII XAFS spectra recorded for the irradiated MOX sub-sample in the rim zone for a 300 ?m300 ?m beam size area investigated over six scans of 4 h. The records remain constant during multi-scan. The analysis of the XAFS signal shows that Am is found as trivalent in the UO? matrix. This analytical work shall open the door of very challenging analysis (speciation of fission product and actinides) in irradiated nuclear fuels. - Highlights: Americium was characterized by microX-ray absorption spectroscopy in irradiated MOX fuel. The americium redox state as determined from XAS data of irradiated fuel material was Am(III). In the sample, the Am? face an AmO??coordination environment in the (Pu,U)O? matrix. The americium dioxide is reduced by the uranium dioxide matrix.

  2. Method and apparatus for aerosol particle absorption spectroscopy

    DOE Patents [OSTI]

    Campillo, Anthony J.; Lin, Horn-Bond

    1983-11-15

    A method and apparatus for determining the absorption spectra, and other properties, of aerosol particles. A heating beam source provides a beam of electromagnetic energy which is scanned through the region of the spectrum which is of interest. Particles exposed to the heating beam which have absorption bands within the band width of the heating beam absorb energy from the beam. The particles are also illuminated by light of a wave length such that the light is scattered by the particles. The absorption spectra of the particles can thus be determined from an analysis of the scattered light since the absorption of energy by the particles will affect the way the light is scattered. Preferably the heating beam is modulated to simplify the analysis of the scattered light. In one embodiment the heating beam is intensity modulated so that the scattered light will also be intensity modulated when the particles absorb energy. In another embodiment the heating beam passes through an interferometer and the scattered light reflects the Fourier Transform of the absorption spectra.

  3. Direct and quantitative broadband absorptance spectroscopy with multilayer cantilever probes

    DOE Patents [OSTI]

    Hsu, Wei-Chun; Tong, Jonathan Kien-Kwok; Liao, Bolin; Chen, Gang

    2015-04-21

    A system for measuring the absorption spectrum of a sample is provided that includes a broadband light source that produces broadband light defined within a range of an absorptance spectrum. An interferometer modulates the intensity of the broadband light source for a range of modulation frequencies. A bi-layer cantilever probe arm is thermally connected to a sample arm having at most two layers of materials. The broadband light modulated by the interferometer is directed towards the sample and absorbed by the sample and converted into heat, which causes a temperature rise and bending of the bi-layer cantilever probe arm. A detector mechanism measures and records the deflection of the probe arm so as to obtain the absorptance spectrum of the sample.

  4. Characterization of a radio frequency carbon nanotube growth plasma by ultraviolet absorption and optical emission spectroscopy

    SciTech Connect (OSTI)

    Cruden, Brett A.; Meyyappan, M.

    2005-04-15

    Radio frequency driven methane/hydrogen plasmas for carbon nanotube growth at pressures between 0.5 and 20 Torr, bias power from 0 to 110 W, and inductive coil power from 0 to 200 W are characterized via optical diagnostics. Ultraviolet absorption spectroscopy is used for quantitative determination of CH{sub 3} radical density for these systems, giving densities on the order of 10{sup 13} cm{sup -3}, accounting for approximately 0.1% of the plasma neutral content. Emission data are also analyzed to extract neutral gas temperatures from the H{sub 2} spectrum and electron densities and temperatures and approximate atomic H densities in the system. Neutral temperature is estimated between 700 and 1100 K, though the lower electrode is heated to 1273 K. Electron temperature is estimated to be between 2.5 and 3.5 eV in the high-energy (>12 eV) portion of the electron energy distribution, and the data suggest an overall non-Maxwellian distribution of electrons. The dissociation of hydrogen is estimated at around 0.1%. Dependencies on power and pressure are explored, indicating more efficient ionization, dissociation, and electron heating at lower pressure and higher power. The absence of any dependency on coil power suggests the plasma is operating in a noninductive mode for these conditions.

  5. X-ray Absorption Spectroscopy Characterization of a Li/S Cell

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

    Ye, Yifan; Kawase, Ayako; Song, Min-Kyu; Feng, Bingmei; Liu, Yi-Sheng; Marcus, Matthew A.; Feng, Jun; Cairns, Elton J.; Guo, Jinghua; Zhu, Junfa

    2016-01-11

    The X-ray absorption spectroscopy technique has been applied to study different stages of the lithium/sulfur (Li/S) cell life cycle. We investigated how speciation of S in Li/S cathodes changes upon the introduction of CTAB (cetyltrimethylammonium bromide, CH3(CH2)15N+(CH3)3Br₋) and with charge/discharge cycling. The introduction of CTAB changes the synthesis reaction pathway dramatically due to the interaction of CTAB with the terminal S atoms of the polysulfide ions in the Na2Sx solution. For the cycled Li/S cell, the loss of electrochemically active sulfur and the accumulation of a compact blocking insulating layer of unexpected sulfur reaction products on the cathode surface duringmore » the charge/discharge processes make the capacity decay. Lastly, a modified coin cell and a vacuum-compatible three-electrode electro-chemical cell have been introduced for further in-situ/in-operando studies.« less

  6. Absolute atomic oxygen and nitrogen densities in radio-frequency driven atmospheric pressure cold plasmas: Synchrotron vacuum ultra-violet high-resolution Fourier-transform absorption measurements

    SciTech Connect (OSTI)

    Niemi, K.; O'Connell, D.; Gans, T.; Oliveira, N. de; Joyeux, D.; Nahon, L.; Booth, J. P.

    2013-07-15

    Reactive atomic species play a key role in emerging cold atmospheric pressure plasma applications, in particular, in plasma medicine. Absolute densities of atomic oxygen and atomic nitrogen were measured in a radio-frequency driven non-equilibrium plasma operated at atmospheric pressure using vacuum ultra-violet (VUV) absorption spectroscopy. The experiment was conducted on the DESIRS synchrotron beamline using a unique VUV Fourier-transform spectrometer. Measurements were carried out in plasmas operated in helium with air-like N{sub 2}/O{sub 2} (4:1) admixtures. A maximum in the O-atom concentration of (9.1 {+-} 0.7) Multiplication-Sign 10{sup 20} m{sup -3} was found at admixtures of 0.35 vol. %, while the N-atom concentration exhibits a maximum of (5.7 {+-} 0.4) Multiplication-Sign 10{sup 19} m{sup -3} at 0.1 vol. %.

  7. Towards simultaneous measurements of electronic and structural properties in ultra-fast x-ray free electron laser absorption spectroscopy experiments

    SciTech Connect (OSTI)

    Gaudin, J.; Fourment, C.; Cho, B. I.; Engelhorn, K.; Galtier, E.; Harmand, M.; Leguay, P. M.; Lee, H. J.; Nagler, B.; Nakatsutsumi, M.; Ozkan, C.; Strmer, M.; Toleikis, S.; Tschentscher, Th.; Heimann, P. A.; Dorchies, F.

    2014-04-17

    The rapidly growing ultrafast science with X-ray lasers unveils atomic scale processes with unprecedented time resolution bringing the so called molecular movie within reach. X-ray absorption spectroscopy is one of the most powerful x-ray techniques providing both local atomic order and electronic structure when coupled with ad-hoc theory. Collecting absorption spectra within few x-ray pulses is possible only in a dispersive setup. We demonstrate ultrafast time-resolved measurements of the LIII-edge x-ray absorption near-edge spectra of irreversibly laser excited Molybdenum using an average of only few x-ray pulses with a signal to noise ratio limited only by the saturation level of the detector. The simplicity of the experimental set-up makes this technique versatile and applicable for a wide range of pump-probe experiments, particularly in the case of non-reversible processes.

  8. Towards simultaneous measurements of electronic and structural properties in ultra-fast x-ray free electron laser absorption spectroscopy experiments

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

    Gaudin, J.; Fourment, C.; Cho, B. I.; Engelhorn, K.; Galtier, E.; Harmand, M.; Leguay, P. M.; Lee, H. J.; Nagler, B.; Nakatsutsumi, M.; et al

    2014-04-17

    The rapidly growing ultrafast science with X-ray lasers unveils atomic scale processes with unprecedented time resolution bringing the so called “molecular movie” within reach. X-ray absorption spectroscopy is one of the most powerful x-ray techniques providing both local atomic order and electronic structure when coupled with ad-hoc theory. Collecting absorption spectra within few x-ray pulses is possible only in a dispersive setup. We demonstrate ultrafast time-resolved measurements of the LIII-edge x-ray absorption near-edge spectra of irreversibly laser excited Molybdenum using an average of only few x-ray pulses with a signal to noise ratio limited only by the saturation level ofmore » the detector. The simplicity of the experimental set-up makes this technique versatile and applicable for a wide range of pump-probe experiments, particularly in the case of non-reversible processes.« less

  9. Spectroscopy

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

    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

  10. A split imaging spectrometer for temporally and spatially resolved titanium absorption spectroscopy

    SciTech Connect (OSTI)

    Hager, J. D. Lanier, N. E.; Kline, J. L.; Flippo, K. A.; Bruns, H. C.; Schneider, M.; Saculla, M.; McCarville, T.

    2014-11-15

    We present a temporally and a spatially resolved spectrometer for titanium x-ray absorption spectroscopy along 2 axial symmetric lines-of-sight. Each line-of-sight of the instrument uses an elliptical crystal to acquire both the 2p and 3p Ti absorption lines on a single, time gated channel of the instrument. The 2 axial symmetric lines-of-sight allow the 2p and 3p absorption features to be measured through the same point in space using both channels of the instrument. The spatially dependent material temperature can be inferred by observing the 2p and the 3p Ti absorption features. The data are recorded on a two strip framing camera with each strip collecting data from a single line-of-sight. The design is compatible for use at both the OMEGA laser and the National Ignition Facility. The spectrometer is intended to measure the material temperature behind a Marshak wave in a radiatively driven SiO{sub 2} foam with a Ti foam tracer. In this configuration, a broad band CsI backlighter will be used for a source and the Ti absorption spectrum measured.

  11. Ligand-field symmetry effects in Fe(II) polypyridyl compounds probed by transient X-ray absorption spectroscopy

    SciTech Connect (OSTI)

    Cho, Hana; Strader, Matthew L.; Hong, Kiryong; Jamula, Lindsey; Kim, Tae Kyu; Groot, Frank M. F. de; McCusker, James K.; Schoenlein, Robert W.; Huse, Nils

    2012-02-28

    Ultrafast excited-state evolution in polypyridyl FeII complexes are of fundamental interest for understanding the origins of the sub-ps spin-state changes that occur upon photoexcitation of this class of compounds as well as for the potential impact such ultrafast dynamics have on incorporation of these compounds in solar energy conversion schemes or switchable optical storage technologies. We have demonstrated that ground-state and, more importantly, ultrafast time-resolved x-ray absorption methods can offer unique insights into the interplay between electronic and geometric structure that underpin the photo-induced dynamics of this class of compounds. The present contribution examines in greater detail how the symmetry of the ligand field surrounding the metal ion can be probed using these x-ray techniques. In particular, we show that steady-state K-edge spectroscopy of the nearest-neighbour nitrogen atoms reveals the characteristic chemical environment of the respective ligands and suggests an interesting target for future charge-transfer femtosecond and attosecond spectroscopy in the x-ray water window.

  12. Femtosecond x-ray absorption spectroscopy with hard x-ray free electron laser

    SciTech Connect (OSTI)

    Katayama, Tetsuo; Togashi, Tadashi; Tono, Kensuke; Kameshima, Takashi; Inubushi, Yuichi; Sato, Takahiro; Hatsui, Takaki; Yabashi, Makina; Obara, Yuki; Misawa, Kazuhiko; Bhattacharya, Atanu; Kurahashi, Naoya; Ogi, Yoshihiro; Suzuki, Toshinori; Molecular Reaction Dynamics Research Team, RIKEN Center for Advanced Photonics, 2-1 Hirosawa, Wako 351-0198

    2013-09-23

    We have developed a method of dispersive x-ray absorption spectroscopy with a hard x-ray free electron laser (XFEL), generated by a self-amplified spontaneous emission (SASE) mechanism. A transmission grating was utilized for splitting SASE-XFEL light, which has a relatively large bandwidth (ΔE/E ∼ 5 × 10{sup −3}), into several branches. Two primary split beams were introduced into a dispersive spectrometer for measuring signal and reference spectra simultaneously. After normalization, we obtained a Zn K-edge absorption spectrum with a photon-energy range of 210 eV, which is in excellent agreement with that measured by a conventional wavelength-scanning method. From the analysis of the difference spectra, the noise ratio was evaluated to be ∼3 × 10{sup −3}, which is sufficiently small to trace minute changes in transient spectra induced by an ultrafast optical laser. This scheme enables us to perform single-shot, high-accuracy x-ray absorption spectroscopy with femtosecond time resolution.

  13. Reflection-Absorption Infrared Spectroscopy of Thin Films Using an External Cavity Quantum Cascade Laser

    SciTech Connect (OSTI)

    Phillips, Mark C.; Craig, Ian M.; Blake, Thomas A.

    2013-02-04

    We present experimental demonstrations using a broadly tunable external cavity quantum cascade laser (ECQCL) to perform Reflection-Absorption InfraRed Spectroscopy (RAIRS) of thin layers and residues on surfaces. The ECQCL compliance voltage was used to measure fluctuations in the ECQCL output power and improve the performance of the RAIRS measurements. Absorption spectra from self-assembled monolayers of a fluorinated alkane thiol and a thiol carboxylic acid were measured and compared with FTIR measurements. RAIRS spectra of the explosive compounds PETN, RDX, and tetryl deposited on gold substrates were also measured. Rapid measurement times and low noise were demonstrated, with < 1E-3 absorbance noise for a 10 second measurement time.

  14. Hydrogen atom temperature measured with wavelength-modulated...

    Office of Scientific and Technical Information (OSTI)

    Subject: 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; 70 PLASMA PHYSICS AND FUSION TECHNOLOGY; ABSORPTION SPECTROSCOPY; ATOMS; DIODE-PUMPED SOLID STATE LASERS; DISTRIBUTION ...

  15. Laser plasma x-ray source for ultrafast time-resolved x-ray absorption spectroscopy

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

    Miaja-Avila, L.; O'Neil, G. C.; Uhlig, J.; Cromer, C. L.; Dowell, M. L.; Jimenez, R.; Hoover, A. S.; Silverman, K. L.; Ullom, J. N.

    2015-03-02

    We describe a laser-driven x-ray plasma source designed for ultrafast x-ray absorption spectroscopy. The source is comprised of a 1 kHz, 20 W, femtosecond pulsed infrared laser and a water target. We present the x-ray spectra as a function of laser energy and pulse duration. Additionally, we investigate the plasma temperature and photon flux as we vary the laser energy. We obtain a 75 μm FWHM x-ray spot size, containing ~106 photons/s, by focusing the produced x-rays with a polycapillary optic. Since the acquisition of x-ray absorption spectra requires the averaging of measurements from >107 laser pulses, we also presentmore » data on the source stability, including single pulse measurements of the x-ray yield and the x-ray spectral shape. In single pulse measurements, the x-ray flux has a measured standard deviation of 8%, where the laser pointing is the main cause of variability. Further, we show that the variability in x-ray spectral shape from single pulses is low, thus justifying the combining of x-rays obtained from different laser pulses into a single spectrum. Finally, we show a static x-ray absorption spectrum of a ferrioxalate solution as detected by a microcalorimeter array. Altogether, our results demonstrate that this water-jet based plasma source is a suitable candidate for laboratory-based time-resolved x-ray absorption spectroscopy experiments.« less

  16. Laser plasma x-ray source for ultrafast time-resolved x-ray absorption spectroscopy

    SciTech Connect (OSTI)

    Miaja-Avila, L.; O'Neil, G. C.; Uhlig, J.; Cromer, C. L.; Dowell, M. L.; Jimenez, R.; Hoover, A. S.; Silverman, K. L.; Ullom, J. N.

    2015-03-02

    We describe a laser-driven x-ray plasma source designed for ultrafast x-ray absorption spectroscopy. The source is comprised of a 1 kHz, 20 W, femtosecond pulsed infrared laser and a water target. We present the x-ray spectra as a function of laser energy and pulse duration. Additionally, we investigate the plasma temperature and photon flux as we vary the laser energy. We obtain a 75 μm FWHM x-ray spot size, containing ~106 photons/s, by focusing the produced x-rays with a polycapillary optic. Since the acquisition of x-ray absorption spectra requires the averaging of measurements from >107 laser pulses, we also present data on the source stability, including single pulse measurements of the x-ray yield and the x-ray spectral shape. In single pulse measurements, the x-ray flux has a measured standard deviation of 8%, where the laser pointing is the main cause of variability. Further, we show that the variability in x-ray spectral shape from single pulses is low, thus justifying the combining of x-rays obtained from different laser pulses into a single spectrum. Finally, we show a static x-ray absorption spectrum of a ferrioxalate solution as detected by a microcalorimeter array. Altogether, our results demonstrate that this water-jet based plasma source is a suitable candidate for laboratory-based time-resolved x-ray absorption spectroscopy experiments.

  17. X-ray absorption spectroscopy studies of electrochemically deposited thin oxide films.

    SciTech Connect (OSTI)

    Balasubramanian, M.

    1998-06-02

    We have utilized ''in situ'' X-ray Absorption Fine Structure Spectroscopy to investigate the structure and composition of thin oxide films of nickel and iron that have been prepared by electrodeposition on a graphite substrate from aqueous solutions. The films are generally disordered. Structural information has been obtained from the analysis of the data. We also present initial findings on the local structure of heavy metal ions, e.g. Sr and Ce, incorporated into the electrodeposited nickel oxide films. Our results are of importance in a number of technological applications, among them, batteries, fuel cells, electrochromic and ferroelectric materials, corrosion protection, as well as environmental speciation and remediation.

  18. Absolute CF{sub 2} density and gas temperature measurements by absorption spectroscopy in dual-frequency capacitively coupled CF{sub 4}/Ar plasmas

    SciTech Connect (OSTI)

    Liu, Wen-Yao; Xu, Yong Peng, Fei; Gong, Fa-Ping; Li, Xiao-Song; Zhu, Ai-Min; Liu, Yong-Xin; Wang, You-Nian

    2014-10-15

    Broadband ultraviolet absorption spectroscopy has been used to determine the CF{sub 2} radical density in dual-frequency capacitively coupled CF{sub 4}/Ar plasmas, using the CF{sub 2} A{sup ~1}B{sub 1}?X{sup ~1}A{sub 1} system of absorption spectrum. The rotational temperature of ground state CF{sub 2} and excited state CF was also estimated by using A{sup ~1}B{sub 1}?X{sup ~1}A{sub 1} system and B{sup 2}??X{sup 2}? system, respectively. The translational gas temperature was deduced from the Doppler width of the Ar{sup *}({sup 3}P{sub 2}) and Ar{sup *}({sup 3}P{sub 0}) metastable atoms absorption line by using the tunable diode laser absorption spectroscopy. The rotational temperatures of the excited state CF are about 100?K higher than those of ground state CF{sub 2}, and about 200?K higher than the translational gas temperatures. The dependences of the radical CF{sub 2} density, electron density, electron temperature, rotational temperature, and gas temperature on the high frequency power and pressure have been analyzed. Furthermore, the production and loss mechanisms of CF{sub 2} radical and the gas heating mechanisms have also been discussed.

  19. Total absorption spectroscopy study of ?Rb decay: A major contributor to reactor antineutrino spectrum shape [Total absorption spectroscopy study of ?Rb: A major contributor to reactor antineutrino flux

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

    Sonzogni, A.; Zakari-Issoufou, A. -A.; Fallot, M.; Porta, A.; Algora, A.; Tain, J. L.; Valencia, E.; Rice, S.; Bui, V. M.; Cormon, S.; et al

    2015-03-09

    The accurate determination of the emitted reactor antineutrino flux is still a major challenge for actual and future neutrino experiments at reactors, especially after the evidence of a disagreement between the measured antineutrino energy spectrum by Double Chooz, Daya Bay, and Reno and calculated antineutrino spectra obtained from the conversion of the unique integral beta spectra measured at the ILL reactor. Using nuclear data to compute reactor antineutrino spectra may help understanding this bias, with the study of the underlying nuclear physics. Summation calculations allow identifying a list of nuclei that contribute importantly to the antineutrino energy spectra emitted aftermorethe fission of ?,?Pu and ?,?U, and whose beta decay properties might deserve new measurements. Among these nuclei, ?Rb exhausts by itself about 16% of of the antineutrino energy spectrum emitted by Pressurized Water Reactors in the 5 to 8 MeV range. In this Letter, we report new Total Absorption Spectroscopy (TAS) results for this important contributor. The obtained beta feeding from ?Rb shows beta intensity unobserved before in the 4.5 to 5.5 MeV energy region and gives a ground state to ground state branch of 87.5 % 3%. These new data induce a dramatic change in recent summation calculations where a 51% GS to GS branch was considered for ?Rb, increasing the summation antineutrino spectrum in the region nearby the observed bias.The new data still have an important impact on other summation calculations in which more recent data were consideredless

  20. Spectroscopy

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

    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

  1. Total absorption spectroscopy study of ?Rb decay: A major contributor to reactor antineutrino spectrum shape [Total absorption spectroscopy study of ?Rb: A major contributor to reactor antineutrino flux

    SciTech Connect (OSTI)

    Sonzogni, A.; Zakari-Issoufou, A. -A.; Fallot, M.; Porta, A.; Algora, A.; Tain, J. L.; Valencia, E.; Rice, S.; Bui, V. M.; Cormon, S.; Estienne, M.; Agramunt, J.; Aysto, J.; Bowry, M.; Briz Monago, J. A.; Caballero-Folch, R.; Cano-Ott, D.; Cucoanes, A.; Eloma, V.; Estvez, E.; Farrelly, G. F.; Garcia, A.; Gelletly, W.; Gomez-Hornillos, M. B.; Gorlychev, V.; Hakala, J.; Jokinen, A.; Jordan, M. D.; Kankainen, A.; Kondev, F. G.; Martinez, T.; Mendoza, E.; Molina, F.; Moore, I.; Perez, A.; Podolyak, Zs.; Penttil, H.; Regan, P. H.; Shiba, T.; Rissanen, J.; Rubio, B.; Weber, C.

    2015-03-09

    The accurate determination of the emitted reactor antineutrino flux is still a major challenge for actual and future neutrino experiments at reactors, especially after the evidence of a disagreement between the measured antineutrino energy spectrum by Double Chooz, Daya Bay, and Reno and calculated antineutrino spectra obtained from the conversion of the unique integral beta spectra measured at the ILL reactor. Using nuclear data to compute reactor antineutrino spectra may help understanding this bias, with the study of the underlying nuclear physics. Summation calculations allow identifying a list of nuclei that contribute importantly to the antineutrino energy spectra emitted after the fission of ?,?Pu and ?,?U, and whose beta decay properties might deserve new measurements. Among these nuclei, ?Rb exhausts by itself about 16% of of the antineutrino energy spectrum emitted by Pressurized Water Reactors in the 5 to 8 MeV range. In this Letter, we report new Total Absorption Spectroscopy (TAS) results for this important contributor. The obtained beta feeding from ?Rb shows beta intensity unobserved before in the 4.5 to 5.5 MeV energy region and gives a ground state to ground state branch of 87.5 % 3%. These new data induce a dramatic change in recent summation calculations where a 51% GS to GS branch was considered for ?Rb, increasing the summation antineutrino spectrum in the region nearby the observed bias.The new data still have an important impact on other summation calculations in which more recent data were considered

  2. Probing the Electronic Structure of a Photoexcited Solar Cell Dye with Transient X-ray Absorption Spectroscopy

    SciTech Connect (OSTI)

    Kuiken, Benjamin E. Van; Huse, Nils; Cho, Hana; Strader, Matthew L.; Lynch, Michael S.; Schoenlein, Robert W.; Khalil, Munira

    2012-05-01

    This study uses transient X-ray absorption (XA) spectroscopy and timedependent density functional theory (TD-DFT) to directly visualize the charge density around the metal atom and the surrounding ligands following an ultrafast metal-to-ligand charge-transfer (MLCT) process in the widely used RuII solar cell dye, Ru(dcbpy)2(NCS)2 (termed N3). We measure the Ru L-edge XA spectra of the singlet ground (1A1) and the transient triplet (3MLCT) excited state of N34 and perform TD-DFT calculations of 2p core-level excitations, which identify a unique spectral signature of the electron density on the NCS ligands. We find that the Ru 2p, Ru eg, and NCS orbitals are stabilized by 2.0, 1.0, and 0.6 eV, respectively, in the transient 3MLCT state of the dye. These results highlight the role of the NCS ligands in governing the oxidation state of the Ru center.

  3. Note: Sample chamber for in situ x-ray absorption spectroscopy studies of battery materials

    SciTech Connect (OSTI)

    Pelliccione, CJ; Timofeeva, EV; Katsoudas, JP; Segre, CU

    2014-12-01

    In situ x-ray absorption spectroscopy (XAS) provides element-specific characterization of both crystalline and amorphous phases and enables direct correlations between electrochemical performance and structural characteristics of cathode and anode materials. In situ XAS measurements are very demanding to the design of the experimental setup. We have developed a sample chamber that provides electrical connectivity and inert atmosphere for operating electrochemical cells and also accounts for x-ray interactions with the chamber and cell materials. The design of the sample chamber for in situ measurements is presented along with example XAS spectra from anode materials in operating pouch cells at the Zn and Sn K-edges measured in fluorescence and transmission modes, respectively. (C) 2014 AIP Publishing LLC.

  4. X-ray Absorption Spectroscopy Beamline at the Siam Photon Laboratory

    SciTech Connect (OSTI)

    Klysubun, Wantana; Tarawarakarn, Pongjakr; Sombunchoo, Panidtha; Klinkhieo, Supat; Chaiprapa, Jitrin; Songsiriritthigul, Prayoon

    2007-01-19

    A bending magnet beamline has been constructed and commissioned for x-ray absorption spectroscopy (XAS) at the Siam Photon Laboratory. The photon energy is tunable from 1830 eV to 8000 eV using a Lemmonier-type, fixed-exit double crystal monochromator equipped with InSb(111), Si(111), Ge(220) crystals. Elemental K-edges are then accessible from silicon to iron. A series of low conductance vacuum tubes has been designed and installed between the pumping chambers in the front end to obtain the proper pressure difference between the upstream and the downstream of the front end. Thus lower-energy photons, around K-edges of silicon, phosphorous, and sulfur, can be delivered to the experimental XAS station without being absorbed by a window. In this report, the design of the beamline is described. The commissioning results including the measured photon flux at sample and experimental XAS spectra are presented.

  5. Millisecond Kinetics of Nanocrystal Cation Exchange UsingMicrofluidic X-ray Absorption Spectroscopy

    SciTech Connect (OSTI)

    Chan, Emory M.; Marcus, Matthew A.; Fakra, Sirine; Elnaggar,Mariam S.; Mathies, Richard A.; Alivisatos, A. Paul

    2007-05-07

    We describe the use of a flow-focusing microfluidic reactorto measure the kinetics of theCdSe-to-Ag2Se nanocrystal cation exchangereaction using micro-X-ray absorption spectroscopy (mu XAS). The smallmicroreactor dimensions facilitate the millisecond mixing of CdSenanocrystal and Ag+ reactant solutions, and the transposition of thereaction time onto spatial coordinates enables the in situ observation ofthe millisecond reaction with mu XAS. XAS spectra show the progression ofCdSe nanocrystals to Ag2Se over the course of 100 ms without the presenceof long-lived intermediates. These results, along with supporting stoppedflow absorption experiments, suggest that this nanocrystal cationexchange reaction is highly efficient and provide insight into how thereaction progresses in individual particles. This experiment illustratesthe value and potential of in situ microfluidic X-ray synchrotrontechniques for detailed studies of the millisecond structuraltransformations of nanoparticles and other solution-phase reactions inwhich diffusive mixing initiates changes in local bond structures oroxidation states.

  6. PROBING THE INNER REGIONS OF PROTOPLANETARY DISKS WITH CO ABSORPTION LINE SPECTROSCOPY

    SciTech Connect (OSTI)

    McJunkin, Matthew; France, Kevin; Burgh, Eric B.; Brown, Alexander; Herczeg, Gregory J.; Schindhelm, Eric; Brown, Joanna M.

    2013-03-20

    Carbon monoxide (CO) is the most commonly used tracer of molecular gas in the inner regions of protoplanetary disks. CO can be used to constrain the excitation and structure of the circumstellar environment. Absorption line spectroscopy provides an accurate assessment of a single line of sight through the protoplanetary disk system, giving more straightforward estimates of column densities and temperatures than CO and molecular hydrogen (H{sub 2}) emission line studies. We analyze new observations of ultraviolet CO absorption from the Hubble Space Telescope along the sightlines to six classical T Tauri stars. Gas velocities consistent with the stellar velocities, combined with the moderate-to-high disk inclinations, argue against the absorbing CO gas originating in a fast-moving disk wind. We conclude that the far-ultraviolet observations provide a direct measure of the disk atmosphere or possibly a slow disk wind. The CO absorption lines are reproduced by model spectra with column densities in the range N({sup 12}CO) {approx} 10{sup 16}-10{sup 18} cm{sup -2} and N({sup 13}CO) {approx} 10{sup 15}-10{sup 17} cm{sup -2}, rotational temperatures T{sub rot}(CO) {approx} 300-700 K, and Doppler b-values, b {approx} 0.5-1.5 km s{sup -1}. We use these results to constrain the line-of-sight density of the warm molecular gas (n{sub CO} {approx} 70-4000 cm{sup -3}) and put these observations in context with protoplanetary disk models.

  7. Near-Edge X-Ray Absorption Fine Structure Spectroscopy of Diamondoid Thiol Monolayers on Gold

    SciTech Connect (OSTI)

    Willey, T.M.; Fabbri, J.D.; Lee, J.R.I.; Schreiner, P.R.; Fokin, A.A.; Tkachenko, B.A.; Fokina, N.A.; Dahl, J.E.P.; Carlson, R.M.K.; Vance, A.L.; Yang, W.; Terminello, L.J.; Buuren, T.van; Melosh, N.A.

    2009-05-26

    Diamondoids, hydrocarbon molecules with cubic-diamond-cage structures, have unique properties with potential value for nanotechnology. The availability and ability to selectively functionalize this special class of nanodiamond materials opens new possibilities for surface modification, for high-efficiency field emitters in molecular electronics, as seed crystals for diamond growth, or as robust mechanical coatings. The properties of self-assembled monolayers (SAMs) of diamondoids are thus of fundamental interest for a variety of emerging applications. This paper presents the effects of thiol substitution position and polymantane order on diamondoid SAMs on gold using near-edge X-ray absorption fine structure spectroscopy (NEXAFS) and X-ray photoelectron spectroscopy (XPS). A framework to determine both molecular tilt and twist through NEXAFS is presented and reveals highly ordered diamondoid SAMs, with the molecular orientation controlled by the thiol location. C 1s and S 2p binding energies are lower in adamantane thiol than alkane thiols on gold by 0.67 {+-} 0.05 and 0.16 {+-} 0.04 eV, respectively. These binding energies vary with diamondoid monolayer structure and thiol substitution position, consistent with different degrees of steric strain and electronic interaction with the substrate. This work demonstrates control over the assembly, in particular the orientational and electronic structure, providing a flexible design of surface properties with this exciting new class of diamond nanoparticles.

  8. Near-Edge X-ray Absorption Fine Structure Spectroscopy of Diamondoid Thiol Monolayers on Gold

    SciTech Connect (OSTI)

    Willey, T M; Fabbri, J; Lee, J I; Schreiner, P; Fokin, A A; Tkachenko, B A; Fokina, N A; Dahl, J; Carlson, B; Vance, A L; Yang, W; Terminello, L J; van Buuren, T; Melosh, N

    2007-11-27

    Diamondoids, hydrocarbon molecules with cubic-diamond-cage structures, have unique properties with potential value for nanotechnology. The availability and ability to selectively functionalize this special class of nanodiamond materials opens new possibilities for surface-modification, for high-efficiency field emitters in molecular electronics, as seed crystals for diamond growth, or as robust mechanical coatings. The properties of self-assembled monolayers (SAMs) of diamondoids are thus of fundamental interest for a variety of emerging applications. This paper presents the effects of thiol substitution position and polymantane order on diamondoid SAMs on gold using near-edge X-ray absorption fine structure spectroscopy (NEXAFS) and X-ray photoelectron spectroscopy (XPS). A framework to determine both molecular tilt and twist through NEXAFS is presented and reveals highly ordered diamondoid SAMs, with the molecular orientation controlled by the thiol location. C 1s and S 2p binding energies are lower in adamantane thiol than alkane thiols on gold by 0.67 {+-} 0.05 eV and 0.16 {+-} 0.04 eV respectively. These binding energies vary with diamondoid monolayer structure and thiol substitution position, consistent with different amounts of steric strain and electronic interaction with the substrate. This work demonstrates control over the assembly, in particular the orientational and electronic structure, providing a flexible design of surface properties with this exciting new class of diamond clusters.

  9. Local structure of Fe in Fe-doped misfit-layered calcium cobaltite: An X-ray absorption spectroscopy study

    SciTech Connect (OSTI)

    Prasoetsopha, Natkrita; Pinitsoontorn, Supree; Bootchanont, Atipong; Kidkhunthod, Pinit; Srepusharawoot, Pornjuk; Kamwanna, Teerasak; Amornkitbamrung, Vittaya; Kurosaki, Ken; Yamanaka, Shinsuke

    2013-08-15

    Polycrystalline Ca{sub 3}Co{sub 4?x}Fe{sub x}O{sub 9+?} ceramics (x=0, 0.01, 0.03, 0.05) were fabricated using a simple thermal hydro-decomposition method and a spark plasma sintering technique. Thermoelectric property measurements showed that increasing Fe concentration resulted in a decrease in electrical resistivity, thermopower and thermal conductivity, leading to an improvement in the dimensionless figure-of-merit, >35% for x=0.05 at 1073 K. An X-ray absorption spectroscopy technique was used to investigate the local structure of Fe ions in the Ca{sub 3}Co{sub 4?x}Fe{sub x}O{sub 9+?} structure for the first time. By fitting data from the extended X-ray absorption fine structure (EXAFS) spectra and analyzing the X-ray absorption near-edge structure (XANES) spectra incorporated with first principle simulation, it was shown that Fe was substituted for Co in the the Ca{sub 2}CoO{sub 3} (rocksalt, RS) layer rather than in the CoO{sub 2} layer. Variation in the thermoelectric properties as a function of Fe concentration was attributed to charge transfer between the CoO{sub 2} and the RS layers. The origin of the preferential Fe substitution site was investigated considering the ionic radii of Co and Fe and the total energy of the system. - Graphical abstract: The Fe K-edge XANES spectra of: (a) experimental result in comparison to the simulated spectra when Fe atoms were substituted in the RS layer; (b) with magnetic moment; (c) without magnetic moment, and in the CoO{sub 2} layer; (d) with magnetic moment and (e) without magnetic moment. Highlights: Synthesis, structural studies, and thermoelectric properties of Ca{sub 3}Co{sub 4?x}Fe{sub x}O{sub 9+?}. Direct evidence for the local structure of the Fe ions in the Ca{sub 3}Co{sub 4?x}Fe{sub x}O{sub 9+?} using XAS analysis. EXAFS and XANES analysis showed that Fe was likely to be situated in the RS layer structure. Changes in TE property with Fe content was due to charge transfer between the CoO{sub 2} and

  10. Quantitative Phase Composition of TiO2-Coated Nanoporous-Au Monoliths by X-ray Absorption Spectroscopy and Correlations to Catalytic

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

    Bagge-Hansen, Michael; Wichmann, Andre; Wittstock, Arne; Lee, Jonathan R. I.; Ye, Jianchao; Willey, Trevor M.; Kuntz, Joshua D.; van Buuren, Tony; Biener, Juergen; Baumer, Marcus; et al

    2014-02-03

    Porous titania/metal composite materials have many potential applications in the fields of green catalysis, energy harvesting, and storage in which both the overall morphology of the nanoporous host material and the crystallographic phase of the titania (TiO 2) guest determine the material’s performance. New insights into the structure–function relationships of these materials were obtained by near-edge X-ray absorption fine structure (NEXAFS) spectroscopy that, for example, provides quantitative crystallographic phase composition from ultrathin, nanostructured titania films, including sensitivity to amorphous components. We demonstrate that crystallographic phase, morphology, and catalytic activity of TiO 2-functionalized nanoporous gold (np-Au) can be controlled by amore » simple annealing procedure (T < 1300 K). The material was prepared by atomic layer deposition of ~2 nm thick TiO2 on millimeter-sized samples of np-Au (40–50 nm mean ligament size) and catalytically investigated with respect to aerobic CO oxidation. Moreover, the annealing-induced changes in catalytic activity are correlated with concurrent morphology and phase changes as provided by cross-sectional scanning electron microscopy, transmission electron microscopy, and near-edge X-ray absorption fine structure (NEXAFS) spectroscopy.« less

  11. A multi-channel monolithic Ge detector system for fluorescence x-ray absorption spectroscopy

    SciTech Connect (OSTI)

    Bucher, J.J.; Allen, P.G.; Edelstein, N.M.; Shuh, D.K.; Madden, N.W.; Cork, C.; Luke, P.; Pehl, D.; Malone, D.

    1995-03-01

    Construction and performance of a monolithic quad-pixel Ge detector for fluorescence x-ray absorption spectroscopy (XAS) at synchrotron radiation sources are described. The detector semiconductor element has an active surface area of 4.0 cm{sup 2} which is electrically separated into four 1.0 cm{sup 2} pixels, with little interfacial dead volume. Spatial response of the array shows that cross-talk between adjacent pixels is < 10% for 5.9 keV photons that fall within 0.5 mm of the pixel boundaries. The detector electronics system uses pre-amplifiers built at LBNL with commercial Tennelec Model TC 244 amplifiers. Using an {sup 55}Fe test source (MnK{sub {alpha}}, 5.9 keV), energy resolution of better than 200 eV is achieved with a 4 {mu}sec peaking time. At 0.5 {mu}sec peaking time, pulse pileup results in a 75% throughput efficiency for an incoming count rate of 100 kHz. Initial XAS fluoresncece measurements at the beamline 4 wiggler end stations at SSRL show that the detector system has several advantages over commercial x-ray spectrometers for low-concentration counting.

  12. The apparent absence of chemical sensitivity in the 4d and 5d X-ray absorption spectroscopy of uranium compounds

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

    Tobin, J. G.

    2013-05-03

    X-ray absorption spectroscopy (XAS) and related derivative measurements have been used to demonstrate that the Pu 5f states are strongly relativistic and have a 5f occupation number near 5. Owing to the success in this regime, it has been argued that the XAS measurements should be a powerful tool to probe 5f occupation variation, both as a function of elemental nature (actinide atomic number) and as a function of physical and chemical perturbation, e.g., oxidation state. We show that XAS and its related measurements fail in this latter aspect for a wide variety of uranium compounds and materials. Possible causesmore » will be discussed.« less

  13. Time-resolved surface infrared spectroscopy during atomic layer deposition of TiO{sub 2} using tetrakis(dimethylamido)titanium and water

    SciTech Connect (OSTI)

    Sperling, Brent A. Hoang, John; Kimes, William A.; Maslar, James E.; Steffens, Kristen L.; Nguyen, Nhan V.

    2014-05-15

    Atomic layer deposition of titanium dioxide using tetrakis(dimethylamido)titanium (TDMAT) and water vapor is studied by reflection-absorption infrared spectroscopy (RAIRS) with a time resolution of 120 ms. At 190 °C and 240 °C, a decrease in the absorption from adsorbed TDMAT is observed without any evidence of an adsorbed product. Ex situ measurements indicate that this behavior is not associated with an increase in the impurity concentration or a dramatic change in the growth rate. A desorbing decomposition product is consistent with these observations. RAIRS also indicates that dehydroxylation of the growth surface occurs only among one type of surface hydroxyl groups. Molecular water is observed to remain on the surface and participates in reactions even at a relatively high temperature (110 °C) and with long purge times (30 s)

  14. Voltage-controlled magnetic anisotropy in Fe|MgO tunnel junctions studied by x-ray absorption spectroscopy

    SciTech Connect (OSTI)

    Miwa, Shinji Matsuda, Kensho; Tanaka, Kazuhito; Goto, Minori; Suzuki, Yoshishige; Kotani, Yoshinori; Nakamura, Tetsuya

    2015-10-19

    In this study, voltage-controlled magnetic anisotropy (VCMA) in Fe|MgO tunnel junctions was investigated via the magneto-optical Kerr effect, soft x-ray absorption spectroscopy, and magnetic circular dichroism spectroscopy. The Fe|MgO tunnel junctions showed enhanced perpendicular magnetic anisotropy under external negative voltage, which induced charge depletion at the Fe|MgO interface. Despite the application of voltages of opposite polarity, no trace of chemical reaction such as a redox reaction attributed to O{sup 2−} migration was detected in the x-ray absorption spectra of the Fe. The VCMA reported in the Fe|MgO-based magnetic tunnel junctions must therefore originate from phenomena associated with the purely electric effect, that is, surface electron doping and/or redistribution induced by an external electric field.

  15. Note: In situ measurement of vacuum window birefringence by atomic spectroscopy

    SciTech Connect (OSTI)

    Steffen, Andreas; Alt, Wolfgang; Genske, Maximilian; Meschede, Dieter; Robens, Carsten; Alberti, Andrea

    2013-12-15

    We present an in situ method to measure the birefringence of a single vacuum window by means of microwave spectroscopy on an ensemble of cold atoms. Stress-induced birefringence can cause an ellipticity in the polarization of an initially linearly polarized laser beam. The amount of ellipticity can be reconstructed by measuring the differential vector light shift of an atomic hyperfine transition. Measuring the ellipticity as a function of the linear polarization angle allows us to infer the amount of birefringence Δn at the level of 10{sup −8} and identify the orientation of the optical axes. The key benefit of this method is the ability to separately characterize each vacuum window, allowing the birefringence to be precisely compensated in existing vacuum apparatuses.

  16. Infrared Absorption Spectroscopy and Chemical Kinetics of Free Radicals. Final Performance Report, August 1, 1985--July 31, 1994

    DOE R&D Accomplishments [OSTI]

    Curl, R. F.; Glass, G. P.

    1995-06-01

    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 its transient infrared absorption is observed using a single frequency cw laser as the source of the infrared probe light. When the probe laser frequency is near the center of an absorption line of the radical produced by the flash, the transient infrared absorption rises rapidly and then decays as the radical reacts with the precursor or with substances introduced for the purpose of studying the reaction kinetics or with itself. The decay times observed in these studies varied from less than one microsecond to more than one millisecond. By choosing appropriate time windows after the flash and the average infrared detector signal in a window as data channels, the infrared spectrum of the radical may be obtained. By locking the infrared probe laser to the center of the absorption line and measuring the rate of decay of the transient infrared absorption signal as the chemical composition of the gas mixture is varied, the chemical kinetics of the radical may be investigated. In what follows the systems investigated and the results obtained are outlined.

  17. A first principle study for the adsorption and absorption of carbon atom and the CO dissociation on Ir(100) surface

    SciTech Connect (OSTI)

    Erikat, I. A.; Hamad, B. A.

    2013-11-07

    We employ density functional theory to examine the adsorption and absorption of carbon atom as well as the dissociation of carbon monoxide on Ir(100) surface. We find that carbon atoms bind strongly with Ir(100) surface and prefer the high coordination hollow site for all coverages. In the case of 0.75 ML coverage of carbon, we obtain a bridging metal structure due to the balance between Ir–C and Ir–Ir interactions. In the subsurface region, the carbon atom prefers the octahedral site of Ir(100) surface. We find large diffusion barrier for carbon atom into Ir(100) surface (2.70 eV) due to the strong bonding between carbon atom and Ir(100) surface, whereas we find a very small segregation barrier (0.22 eV) from subsurface to the surface. The minimum energy path and energy barrier for the dissociation of CO on Ir(100) surface are obtained by using climbing image nudge elastic band. The energy barrier of CO dissociation on Ir(100) surface is found to be 3.01 eV, which is appreciably larger than the association energy (1.61 eV) of this molecule.

  18. Combining Feedback Absorption Spectroscopy, Amplified Resonance and Low Pressure Sampling for the Measurement of Nitrogen-Containing Compounds in Automotive Emissions

    Broader source: Energy.gov [DOE]

    Discusses a novel combination of multi-component scanning direct absorption spectroscopy, resonant cavity and low-pressure sampling to systematically improve the performance of a specific gas analyzer.

  19. Particle size effect of hydride formation and surface hydrogen absorption of nanosized palladium catalysts : L{sub 3} edge vs K edge x-ray absorption spectroscopy.

    SciTech Connect (OSTI)

    Tew, M. W.; Miller, J. T.; van Bokhoven, J. A.

    2009-08-01

    The particle size effect on the formation of palladium hydride and on surface hydrogen adsorption was studied at room temperature using in situ X-ray absorption spectroscopy at the Pd K and L{sub 3} edges. Hydride formation was indirectly observed by lattice expansion in Pd K edge XANES spectra and by EXAFS analysis. Hydride formation was directly detected in the L{sub 3} edge spectra. A characteristic spectral feature caused by the formation of a Pd-H antibonding state showed strong particle size dependence. The L{sub 3} edge spectra were reproduced using full multiple scattering analysis and density of state calculations, and the contributions of bulk absorbed and surface hydrogen to the XANES spectra could be distinguished. The ratio of hydrogen on the surface versus that in the bulk increased with decreasing particle size, and smaller particles dissolved less hydrogen.

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

    Broader source: Energy.gov [DOE]

    Observing an atom's electrons moving in real time -- for the first time ever; and how to slow down DNA for easier sequencing.

  1. High energy resolution five-crystal spectrometer for high quality fluorescence and absorption measurements on an x-ray absorption spectroscopy beamline

    SciTech Connect (OSTI)

    Llorens, Isabelle; Lahera, Eric; Delnet, William; Proux, Olivier; Dermigny, Quentin; Gelebart, Frederic; Morand, Marc; Shukla, Abhay; Bardou, Nathalie; Ulrich, Olivier; and others

    2012-06-15

    Fluorescence detection is classically achieved with a solid state detector (SSD) on x-ray absorption spectroscopy (XAS) beamlines. This kind of detection however presents some limitations related to the limited energy resolution and saturation. Crystal analyzer spectrometers (CAS) based on a Johann-type geometry have been developed to overcome these limitations. We have tested and installed such a system on the BM30B/CRG-FAME XAS beamline at the ESRF dedicated to the structural investigation of very dilute systems in environmental, material and biological sciences. The spectrometer has been designed to be a mobile device for easy integration in multi-purpose hard x-ray synchrotron beamlines or even with a laboratory x-ray source. The CAS allows to collect x-ray photons from a large solid angle with five spherically bent crystals. It will cover a large energy range allowing to probe fluorescence lines characteristic of all the elements from Ca (Z = 20) to U (Z = 92). It provides an energy resolution of 1-2 eV. XAS spectroscopy is the main application of this device even if other spectroscopic techniques (RIXS, XES, XRS, etc.) can be also achieved with it. The performances of the CAS are illustrated by two experiments that are difficult or impossible to perform with SSD and the complementarity of the CAS vs SSD detectors is discussed.

  2. X-ray absorption spectroscopy of Mn doped ZnO thin films prepared by rf sputtering technique

    SciTech Connect (OSTI)

    Yadav, Ashok Kumar; Jha, S. N.; Bhattacharyya, D.; Haque, Sk Maidul; Shukla, Dinesh; Choudhary, Ram Janay

    2015-11-15

    A set of r.f. sputter deposited ZnO thin films prepared with different Mn doping concentrations have been characterised by Extended X-ray Absorption Fine Structure (EXAFS) and X-ray Absorption Near Edge Spectroscopy (XANES) measurements at Zn, Mn and O K edges and at Mn L{sub 2,3} edges apart from long range structural characterisation by Grazing Incident X-ray Diffraction (GIXRD) technique. Magnetic measurements show room temperature ferromagnetism in samples with lower Mn doping which is however, gets destroyed at higher Mn doping concentration. The results of the magnetic measurements have been explained using the local structure information obtained from EXAFS and XANES measurements.

  3. Simulating Ru L3-Edge X-ray Absorption Spectroscopy with Time-Dependent Density Functional Theory: Model Complexes and Electron Localization in Mixed-Valence Metal Dimers

    SciTech Connect (OSTI)

    Kuiken, Benjamin E. Van; Valiev, Marat; Daifuku, Stephanie L.; Bannan, Caitlin; Strader, Matthew L.; Cho, Hana; Huse, Nils; Schoenlein, Robert W.; Govind, Niranjan; Khalil, Munira

    2013-04-26

    Ruthenium L3-edge X-ray absorption (XA) spectroscopy probes unoccupied 4d orbitals of the metal atom and is increasingly being used to investigate the local electronic structure in ground and excited electronic states of Ru complexes. The simultaneous development of computational tools for simulating Ru L3-edge spectra is crucial for interpreting the spectral features at a molecular level. This study demonstrates that time-dependent density functional theory (TDDFT) is a viable and predictive tool for simulating ruthenium L3-edge XA spectroscopy. We systematically investigate the effects of exchange correlation functional and implicit and explicit solvent interactions on a series of RuII and RuIII complexes in their ground and electronic excited states. The TDDFT simulations reproduce all of the experimentally observed features in Ru L3-edge XA spectra within the experimental resolution (0.4 eV). Our simulations identify ligand-specific charge transfer features in complicated Ru L3-edge spectra of [Ru(CN)6]4- and RuII polypyridyl complexes illustrating the advantage of using TDDFT in complex systems. We conclude that the B3LYP functional most accurately predicts the transition energies of charge transfer features in these systems. We use our TDDFT approach to simulate experimental Ru L3-edge XA spectra of transition metal mixed-valence dimers of the form [(NC)5MII-CN-RuIII(NH3)5] (where M = Fe or Ru) dissolved in water. Our study determines the spectral signatures of electron delocalization in Ru L3-edge XA spectra. We find that the inclusion of explicit solvent molecules is necessary for reproducing the spectral features and the experimentally determined valencies in these mixed-valence complexes. This study validates the use of TDDFT for simulating Ru 2p excitations using popular quantum chemistry codes and providing a powerful interpretive tool for equilibrium and ultrafast Ru L3-edge XA spectroscopy.

  4. Improved graphite furnace atomizer

    DOE Patents [OSTI]

    Siemer, D.D.

    1983-05-18

    A graphite furnace atomizer for use in graphite furnace atomic absorption spectroscopy is described wherein the heating elements are affixed near the optical path and away from the point of sample deposition, so that when the sample is volatilized the spectroscopic temperature at the optical path is at least that of the volatilization temperature, whereby analyteconcomitant complex formation is advantageously reduced. The atomizer may be elongated along its axis to increase the distance between the optical path and the sample deposition point. Also, the atomizer may be elongated along the axis of the optical path, whereby its analytical sensitivity is greatly increased.

  5. Mapping of upper electronic reaction surfaces by tuned laser photolysis and by absorption and emission spectroscopies

    SciTech Connect (OSTI)

    Morgan, M.A.

    1989-07-01

    Potential energy surfaces for photorotamerization of two intramolecularly hydrogen-bonded molecules, o-hydroxybenzaldehyde (OHBA) and methyl salicylate (MS), isolated in cryogenic matrices have been spectroscopically mapped. In addition, the external heavy atom effect of krypton and xenon matrices on the coupling between the S{sub 1} and T{sub 1} surfaces of 4-(dimethylamino)benzonitrile has been examined. Heavy atom matrices are known to increase rates of spin-forbidden processes. The phosphorescence intensity of DMABN increases in krypton and xenon matrices, while the fluorescence intensity, and phosphorescence and fluorescence lifetimes, decrease. These effects are interpreted in terms of a model in which the phosphorescence rate constant increases 300-fold in xenon compared to argon, while the rate constants for intersystem crossing and nonradiative relaxation from the triplet state increase by factors of less than 5. Lifetime measurements in argon matrices doped with heavy atoms indicate that even one heavy atom neighbor has a significant effect on both singlet and triplet lifetimes. 78 refs., 35 figs., 15 tabs.

  6. Local electronic states of Fe{sub 4}N films revealed by x-ray absorption spectroscopy and x-ray magnetic circular dichroism

    SciTech Connect (OSTI)

    Ito, Keita; Toko, Kaoru; Suemasu, Takashi; Takeda, Yukiharu; Saitoh, Yuji; Oguchi, Tamio; Kimura, Akio

    2015-05-21

    We performed x-ray absorption spectroscopy (XAS) and x-ray magnetic circular dichroism (XMCD) measurements at Fe L{sub 2,3} and N K-edges for Fe{sub 4}N epitaxial films grown by molecular beam epitaxy. In order to clarify the element specific local electronic structure of Fe{sub 4}N, we compared experimentally obtained XAS and XMCD spectra with those simulated by a combination of a first-principles calculation and Fermi's golden rule. We revealed that the shoulders observed at Fe L{sub 2,3}-edges in the XAS and XMCD spectra were due to the electric dipole transition from the Fe 2p core-level to the hybridization state generated by ?* anti-bonding between the orbitals of N 2p at the body-centered site and Fe 3d on the face-centered (II) sites. Thus, the observed shoulders were attributed to the local electronic structure of Fe atoms at II sites. As to the N K-edge, the line shape of the obtained spectra was explained by the dipole transition from the N 1s core-level to the hybridization state formed by ?* and ?* anti-bondings between the Fe 3d and N 2p orbitals. This hybridization plays an important role in featuring the electronic structures and physical properties of Fe{sub 4}N.

  7. Observing heme doming in myoglobin with femtosecond X-ray absorption spectroscopy

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

    Levantino, M.; Lemke, H. T.; Schirò, G.; Glownia, M.; Cupane, A.; Cammarata, M.

    2015-07-01

    We report time-resolved X-ray absorption measurements after photolysis of carbonmonoxy myoglobin performed at the LCLS X-ray free electron laser with nearly 100 fs (FWHM) time resolution. Data at the Fe K-edge reveal that the photoinduced structural changes at the heme occur in two steps, with a faster (~70 fs) relaxation preceding a slower (~400 fs) one. We tentatively attribute the first relaxation to a structural rearrangement induced by photolysis involving essentially only the heme chromophore and the second relaxation to a residual Fe motion out of the heme plane that is coupled to the displacement of myoglobin F-helix.

  8. X-ray absorption spectroscopy of strongly disordered glasses: Local structure around Ag ions in g-Ag{sub 2}O{center_dot}nB{sub 2}O{sub 3}

    SciTech Connect (OSTI)

    Kuzmin, A.; Dalba, G.; Fornasini, P.; Rocca, F.; Sipr, O.

    2006-05-01

    The local structure around Ag ions in silver borate glasses g-Ag{sub 2}O{center_dot}nB{sub 2}O{sub 3} (n=2,4) was studied by x-ray absorption spectroscopy at the Ag K edge for temperatures from 77 to 450 K. Extended x-ray absorption fine structure (EXAFS) analysis based on cumulant expansion or multishell Gaussian model fails for these systems. Therefore, the radial distribution functions (RDFs) around Ag ions were reconstructed using a method based on the direct inversion of the EXAFS expression. The RDFs consist of about eight atoms (oxygens and borons), exhibit a relatively weak temperature dependence, and indicate the presence of strong static disorder. Two main components can be identified in RDFs, located at about 2.3-2.4 A and 2.5-3.4 A, respectively. The chemical types of atoms contributing to the RDF were determined via a simulation of configurationally averaged x-ray absorption near-edge structure (XANES) and EXAFS signals. The immediate neighborhood of Ag contains mostly oxygens while borons dominate at larger distances. The combination of EXAFS and XANES techniques allowed us to determine a more complete structural model than would be possible by relying solely on either EXAFS or XANES alone.

  9. Theoretical study of Raman chirped adiabatic passage by X-ray absorption spectroscopy: Highly excited electronic states and rotational effects

    SciTech Connect (OSTI)

    Engin, Selma; Sisourat, Nicolas Selles, Patricia; Taïeb, Richard; Carniato, Stéphane

    2014-06-21

    Raman Chirped Adiabatic Passage (RCAP) is an efficient method to climb the vibrational ladder of molecules. It was shown on the example of fixed-in-space HCl molecule that selective vibrational excitation can thus be achieved by RCAP and that population transfer can be followed by X-ray Photoelectron spectroscopy [S. Engin, N. Sisourat, P. Selles, R. Taïeb, and S. Carniato, Chem. Phys. Lett. 535, 192–195 (2012)]. Here, in a more detailed analysis of the process, we investigate the effects of highly excited electronic states and of molecular rotation on the efficiency of RCAP. Furthermore, we propose an alternative spectroscopic way to monitor the transfer by means of X-ray absorption spectra.

  10. The detection of carbon dioxide leaks using quasi-tomographic laser absorption spectroscopy measurements in variable wind

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

    Levine, Zachary H.; Pintar, Adam L.; Dobler, Jeremy T.; Blume, Nathan; Braun, Michael; Zaccheo, T. Scott; Pernini, Timothy G.

    2016-04-13

    Laser absorption spectroscopy (LAS) has been used over the last several decades for the measurement of trace gasses in the atmosphere. For over a decade, LAS measurements from multiple sources and tens of retroreflectors have been combined with sparse-sample tomography methods to estimate the 2-D distribution of trace gas concentrations and underlying fluxes from point-like sources. In this work, we consider the ability of such a system to detect and estimate the position and rate of a single point leak which may arise as a failure mode for carbon dioxide storage. The leak is assumed to be at a constant ratemore » giving rise to a plume with a concentration and distribution that depend on the wind velocity. We demonstrate the ability of our approach to detect a leak using numerical simulation and also present a preliminary measurement.« less

  11. The detection of carbon dioxide leaks using quasi-tomographic laser absorption spectroscopy measurements in variable wind

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

    Levine, Z. H.; Pintar, A. L.; Dobler, J.; Blume, N.; Braun, M.; Zaccheo, T. S.; Pernini, T. G.

    2015-11-24

    Laser Absorption Spectroscopy (LAS) has been used over the last several decades for the measurement of trace gasses in the atmosphere. For over a decade, LAS measurements from multiple sources and tens of retroreflectors have been combined with sparse-sample tomography methods to estimate the 2-D distribution of trace gas concentrations and underlying fluxes from pointlike sources. In this work, we consider the ability of such a system to detect and estimate the position and rate of a single point leak which may arise as a failure mode for carbon dioxide storage. The leak is assumed to be at a constantmorerate giving rise to a plume with a concentration and distribution that depend on the wind velocity. We demonstrate the ability of our approach to detect a leak using numerical simulation and a preliminary measurement.less

  12. Experimental station for laser-based picosecond time-resolved x-ray absorption near-edge spectroscopy

    SciTech Connect (OSTI)

    Dorchies, F. Fedorov, N.; Lecherbourg, L.

    2015-07-15

    We present an experimental station designed for time-resolved X-ray Absorption Near-Edge Spectroscopy (XANES). It is based on ultrashort laser-plasma x-ray pulses generated from a table-top 100 mJ-class laser at 10 Hz repetition rate. A high transmission (10%–20%) x-ray beam line transport using polycapillary optics allows us to set the sample in an independent vacuum chamber, providing high flexibility over a wide spectral range from 0.5 up to 4 keV. Some XANES spectra are presented, demonstrating 1% noise level in only ∼1 mn and ∼100 cumulated laser shots. Time-resolved measurements are reported, indicating that the time resolution of the entire experimental station is 3.3 ± 0.6 ps rms.

  13. The detection of carbon dioxide leaks using quasi-tomographic laser absorption spectroscopy measurements in variable wind

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

    Levine, Zachary H.; Pintar, Adam L.; Dobler, Jeremy T.; Blume, Nathan; Braun, Michael; Zaccheo, T. Scott; Pernini, Timothy G.

    2016-04-13

    Laser absorption spectroscopy (LAS) has been used over the last several decades for the measurement of trace gasses in the atmosphere. For over a decade, LAS measurements from multiple sources and tens of retroreflectors have been combined with sparse-sample tomography methods to estimate the 2-D distribution of trace gas concentrations and underlying fluxes from point-like sources. In this work, we consider the ability of such a system to detect and estimate the position and rate of a single point leak which may arise as a failure mode for carbon dioxide storage. The leak is assumed to be at a constant ratemore » giving rise to a plume with a concentration and distribution that depend on the wind velocity. Lastly, we demonstrate the ability of our approach to detect a leak using numerical simulation and also present a preliminary measurement.« less

  14. Low level absorptance measurements and scans of high performance optical coatings for atomic vapor laser isotope separation applications

    SciTech Connect (OSTI)

    Chow, R.; Taylor, J.R.; Wu, Z.L.; Krupka, R.; Yang, T.

    1998-01-24

    A surface thermal lensing and a radiometric technique was used to characterize the absorptance dependence on time, power, site, and technique of low absorptance optical multilayered coatings.

  15. Auto-oligomerization and hydration of pyrrole revealed by x-ray absorption spectroscopy

    SciTech Connect (OSTI)

    Advanced Light Source; Schwartz, Craig P.; Uejio, Janel S.; Duffin, Andrew M.; England, Alice H.; Prendergast, David; Saykally, Richard J

    2009-05-29

    Near edge x-ray absorption fine structure (NEXAFS) spectra have been measured at the carbon and nitrogen K-edges of the prototypical aromatic molecule, pyrrole, both in the gas phase and when solvated in water, and compared with spectra simulated using a combination of classical molecular dynamics and first principles density functional theory in the excited state core hole approximation. The excellent agreement enabled detailed assignments. Pyrrole is highly reactive, particularly in water, and reaction products formed by the auto-oligomerization of pyrrole are identified. The solvated spectra have been measured at two different temperatures, indicating that the final states remain largely unaffected by both hydration and temperature. This is somewhat unexpected, since the nitrogen in pyrrole can donate a hydrogen bond to water.

  16. In operando observation system for electrochemical reaction by soft X-ray absorption spectroscopy with potential modulation method

    SciTech Connect (OSTI)

    Nagasaka, Masanari Kosugi, Nobuhiro; Yuzawa, Hayato; Horigome, Toshio

    2014-10-15

    In order to investigate local structures of electrolytes in electrochemical reactions under the same scan rate as a typical value 100 mV/s in cyclic voltammetry (CV), we have developed an in operando observation system for electrochemical reactions by soft X-ray absorption spectroscopy (XAS) with a potential modulation method. XAS spectra of electrolytes are measured by using a transmission-type liquid flow cell with built-in electrodes. The electrode potential is swept with a scan rate of 100 mV/s at a fixed photon energy, and soft X-ray absorption coefficients at different potentials are measured at the same time. By repeating the potential modulation at each fixed photon energy, it is possible to measure XAS of electrochemical reaction at the same scan rate as in CV. We have demonstrated successful measurement of the Fe L-edge XAS spectra of aqueous iron sulfate solutions and of the change in valence of Fe ions at different potentials in the Fe redox reaction. The mechanism of these Fe redox processes is discussed by correlating the XAS results with those at different scan rates.

  17. Determining Orientational Structure of Diamondoid Thiols Attached to Silver Using Near Edge X-ray Absorption Fine Structure Spectroscopy

    SciTech Connect (OSTI)

    Willey, T M; Lee, J I; Fabbri, J D; Wang, D; Nielsen, M; Randel, J C; Schreiner, P R; Fokin, A A; Tkachenko, B A; Fokina, N A; Dahl, J P; Carlson, R K; Terminello, L J; Melosh, N A; van Buuren, T

    2008-10-07

    Near-edge x-ray absorption fine structure spectroscopy (NEXAFS) is a powerful tool for determination of molecular orientation in self-assembled monolayers and other surface-attached molecules. A general framework for using NEXAFS to simultaneously determine molecular tilt and twist of rigid molecules attached to surfaces is presented. This framework is applied to self-assembled monolayers of higher diamondoid, hydrocarbon molecules with cubic-diamond-cage structures. Diamondoid monolayers chemisorbed on metal substrates are known to exhibit interesting electronic and surface properties. This work compares molecular orientation in monolayers prepared on silver substrates using two different thiol positional isomers of [121]tetramantane, and thiols derived from two different pentamantane structural isomers, [1212]pentamantane and [1(2,3)4]pentamantane. The observed differences in monolayer structure demonstrate the utility and limitations of NEXAFS spectroscopy and the framework. The results also demonstrate the ability to control diamondoid assembly, in particular the molecular orientational structure, providing a flexible platform for the modification of surface properties with this exciting new class of nanodiamond materials.

  18. MOSFIRE ABSORPTION LINE SPECTROSCOPY OF z > 2 QUIESCENT GALAXIES: PROBING A PERIOD OF RAPID SIZE GROWTH

    SciTech Connect (OSTI)

    Belli, Sirio; Ellis, Richard S.; Konidaris, Nick P.; Newman, Andrew B.

    2014-06-20

    Using the MOSFIRE near-infrared multi-slit spectrograph on the Keck 1 Telescope, we have secured high signal-to-noise ratio absorption line spectra for six massive galaxies with redshift 2 < z < 2.5. Five of these galaxies lie on the red sequence and show signatures of passive stellar populations in their rest-frame optical spectra. By fitting broadened spectral templates we have determined stellar velocity dispersions and, with broad-band Hubble Space Telescope and Spitzer photometry and imaging, stellar masses and effective radii. Using this enlarged sample of galaxies, we confirm earlier suggestions that quiescent galaxies at z > 2 have small sizes and large velocity dispersions compared to local galaxies of similar stellar mass. The dynamical masses are in very good agreement with stellar masses (log M {sub *}/M {sub dyn} = –0.02 ± 0.03), although the average stellar-to-dynamical mass ratio is larger than that found at lower redshift (–0.23 ± 0.05). By assuming evolution at fixed velocity dispersion, not only do we confirm a surprisingly rapid rate of size growth but we also consider the necessary evolutionary track on the mass-size plane and find a slope α = dlog R{sub e} /dlog M {sub *} ≳ 2 inconsistent with most numerical simulations of minor mergers. Both results suggest an additional mechanism may be required to explain the size growth of early galaxies.

  19. Dielectric spectroscopy at the nanoscale by atomic force microscopy: A simple model linking materials properties and experimental response

    SciTech Connect (OSTI)

    Miccio, Luis A. Colmenero, Juan; Kummali, Mohammed M.; Alegra, ngel; Schwartz, Gustavo A.

    2014-05-14

    The use of an atomic force microscope for studying molecular dynamics through dielectric spectroscopy with spatial resolution in the nanometer scale is a recently developed approach. However, difficulties in the quantitative connection of the obtained data and the material dielectric properties, namely, frequency dependent dielectric permittivity, have limited its application. In this work, we develop a simple electrical model based on physically meaningful parameters to connect the atomic force microscopy (AFM) based dielectric spectroscopy experimental results with the material dielectric properties. We have tested the accuracy of the model and analyzed the relevance of the forces arising from the electrical interaction with the AFM probe cantilever. In this way, by using this model, it is now possible to obtain quantitative information of the local dielectric material properties in a broad frequency range. Furthermore, it is also possible to determine the experimental setup providing the best sensitivity in the detected signal.

  20. Probing non-adiabatic conical intersections using absorption, spontaneous Raman, and femtosecond stimulated Raman spectroscopy

    SciTech Connect (OSTI)

    Patuwo, Michael Y.; Lee, Soo-Y.

    2013-12-21

    We present the time-frame calculated photoabsorption spectrum (ABS), spontaneous Raman excitation profile (REP), femtosecond stimulated Raman spectroscopy (FSRS) spectrum, and femtosecond stimulated Raman excitation profile (FSREP) results of a two-mode and three-mode, three-electronic-states model Hamiltonians containing conical intersections (CIs) along its two upper diabatic electronic states, e{sub 1} (dark) and e{sub 2} (bright), with and without coupling (nonadiabatic dynamics) along an asymmetric mode. For every electronic state in each model, there is one coupling mode and the rest of the modes are symmetric tuning modes. The CI appears in the Hamiltonian as off-diagonal entries to the potential term that couple the two upper states, in the form of a linear function of the coupling mode. We show that: (a) the ABS, REP, and FSREP for Stokes and anti-Stokes lines contain similar information about the e{sub 1} and e{sub 2} vibrational bands, (b) the FSRS spectra feature narrow stationary peaks and broader moving peaks contributed by the different resonant components of the third-order polarization terms from perturbation theory, and (c) a relatively strong and narrow stationary band of the allowed first overtone of the asymmetric coupling mode is observed in the Stokes FSREP in the e{sub 1} energy region with coupling to e{sub 2}.

  1. Near-infrared spectroscopy of CH{sub 2} by frequency modulated diode laser absorption

    SciTech Connect (OSTI)

    Marr, A.J.; Sears, T.J.; Chang, B.

    1998-09-01

    A diode laser spectrometer incorporating a multi-pass Herriott type cell and frequency modulation detection was used to record a previously unaccessed region of the near-infrared singlet{l_arrow}singlet absorption spectrum of methylene between 10thinsp000 cm{sup {minus}1} and 10thinsp600 cm{sup {minus}1}. With this spectrometer, signal-to-noise ratios close to the quantum noise limit have been attained. Identification of rovibronic transitions to five previously unobserved levels, K=1 {tilde a}(0,9,0), K=2thinsp{tilde b}(0,1,0), K=2thinsp{tilde a}(1,6,0), K=3thinsp{tilde b}(0,1,0) and K=3thinsp{tilde a}(0,10,0), was made. Despite the fact that the present spectra access levels within approximately 1300 cm{sup {minus}1} of the barrier to linearity, the spectrum is dense and perturbed, characteristics in common with spectra recorded in many previous studies at shorter wavelengths. Recent spectroscopic observations of halomethylenes [J. Mol. Spectrosc. {bold 188}, 68 (1998)] had suggested that the CH{sub 2} spectrum might become simpler at longer wavelengths, but this was not evident in the observed spectra. The mixed nature of the singlet states is evidenced by the assignment of rovibronic transitions to levels containing primarily {tilde a}thinsp{sup 1}A{sub 1} state character. The new measurements provide a stringent test for modern theoretical models for CH{sub 2} and will enable refinement of the electronic potential surfaces. {copyright} {ital 1998 American Institute of Physics.}

  2. Atomic and electronic structures of SrTiO3/GaAs heterointerfaces: An 80-kV atomic-resolution electron energy-loss spectroscopy study

    SciTech Connect (OSTI)

    Qiao, Q.; Klie, Robert F; Ogut, Serdar; Idrobo Tapia, Juan C

    2012-01-01

    We have examined the atomic and electronic structures of epitaxially grown, ultrathin SrTiO{sub 3} (100) films on GaAs (001) using 80-kV aberration-corrected atomic-resolution Z-contrast imaging and electron energy-loss spectroscopy (EELS) to develop a fundamental understanding of the interfacial structure-property relationships. We find that the interface is atomically abrupt and no surface reconstruction of the GaAs (001) surface is observed. Using atomic-column resolved EELS, we examine the oxygen vacancy and Ti concentrations in the SrTiO{sub 3} film and across the heterointerface. We show that Ti diffuses into the first few monolayers of GaAs. Using a combination of EELS and first-principles calculations, we present evidence for the formation of As oxides at the interface depending on the thin-film growth conditions. These findings are used to explain the differences in the transport behavior of the films.

  3. X-ray absorption spectroscopy on the calcium cofactor to the manganese cluster in photosynthetic oxygen evolution

    SciTech Connect (OSTI)

    Cinco, Roehl M.

    1999-12-16

    Along with Mn, calcium and chloride ions are necessary cofactors for oxygen evolution in Photosystem II (PS II). To further test and verify whether Ca is close to the Mn cluster, the authors substituted strontium for Ca and probed from the Sr point of view for any nearby Mn. The extended X-ray absorption fine structure (EXAFS) of Sr-reactivated PS II indicates major differences between the intact and NH{sub 2}OH-treated samples. In intact samples, the Fourier transform of the Sr EXAFS shows a Fourier peak that is missing in inactive samples. This peak II is best simulated by two Mn neighbors at a distance of 3.5 Angstrom, confirming the proximity of Ca (Sr) cofactor to the Mn cluster. In addition, polarized Sr EXAFS on oriented Sr-reactivated samples shows this peak II is dichroic: large magnitude at 10 degrees (angle between the PS II membrane normal and the x-ray electric field vector) and small at 80 degrees. Analysis of the dichroism yields the relative angle between the Sr-Mn vector and membrane normal (23 degrees {+-} 4 degrees), and the isotropic coordination number for these layered samples. X-ray absorption spectroscopy has also been employed to assess the degree of similarity between the manganese cluster in PS II and a family of synthetic manganese complexes containing the distorted cubane [Mn{sub 4}O{sub 3}X] core (X = benzoate, acetate, methoxide, hydroxide, azide, fluoride, chloride or bromide). In addition, Mn{sub 4}O{sub 3}Cl complexes containing three or six terminal Cl ligands at three of the Mn were included in this study. The EXAFS method detects the small changes in the core structures as X is varied in this series, and serves to exclude these distorted cubanes of C3v symmetry as a topological model for the Mn catalytic cluster. The sulfur K-edge x-ray absorption near-edge structure (XANES) spectra for the amino acids cysteine, methionine, their corresponding oxidized forms cystine and methionine sulfoxide, and glutathione show distinct

  4. Electronic structure of Al-doped ZnO transparent conductive thin films studied by x-ray absorption and emission spectroscopies

    SciTech Connect (OSTI)

    Huang, W. H.; Sun, S. J.; Chiou, J. W.; Chou, H.; Chan, T. S.; Lin, H.-J.; Kumar, Krishna; Guo, J.-H.

    2011-11-15

    This study used O K-, Zn L{sub 3}-, Zn K-, and Al K-edges x-ray absorption near-edge structure (XANES) and O K-edge x-ray emission spectroscopy (XES) measurements to investigate the electronic structure of transparent Al-doped ZnO (AZO) thin film conductors. The samples were prepared on glass substrates at a low temperature near 77 K by using a standard RF sputtering method. High-purity Ne (5N) was used as the sputtering gas. The crystallography of AZO thin films gradually transformed from the ZnO wurtize structure to an amorphous structure during sample deposition, which suggests the suitability to grow on flexible substrates, eliminating the severe degradation due to fragmentation by repeated bending. The O K- and Zn L{sub 3}-edges XANES spectra of AZO thin films revealed a decrease in the number of both O 2p and Zn 3d unoccupied states when the pressure of Ne was increased from 5 to 100 mTorr. In contrast, Al K-edges XANES spectra showed that the number of unoccupied states of Al 3p increased in conjunction with the pressure of Ne, indicating an electron transfer from Al to O atoms, and suggesting that Al doping increases the negative effective charge of oxygen ions. XES and XANES spectra of O 2p states at the O K-edge also revealed that Al doping not only raised the conduction-band-minimum, but also increased the valence-band-maximum and the band-gap. The results indicate that the reduction in conductivity of AZO thin films is due to the generation of ionic characters, the increase in band-gap, and the decrease in density of unoccupied states of oxygen.

  5. Determining copper and lead binding in Larrea tridentata through chemical modification and X-ray absorption spectroscopy

    SciTech Connect (OSTI)

    Polette, L.; Gardea-Torresdey, J.L.; Chianelli, R.; Pickering, I.J.; George, G.N.

    1997-12-31

    Metal contamination in soils has become a widespread problem. Emerging technologies, such as phytoremediation, may offer low cost cleanup methods. The authors have identified a desert plant, Larrea tridentata (creosote bush), which naturally grows and uptakes copper and lead from a contaminated area near a smelting operation. They determined, through chemical modification of carboxyl groups with methanol, that these functional groups may be responsible for a portion of copper(II) binding. In contrast, lead binding was minimally affected by modification of carboxyl groups. X-ray absorption spectroscopy studies conducted at Stanford Synchrotron Radiation Laboratory (SSRL) further support copper binding to oxygen-coordinated ligands and also imply that the binding is not solely due to phytochelatins. The EXAFS data indicate the presence of both Cu-O and Cu-S back scatters, no short Cu-Cu interactions, but with significant Cu-Cu back scattering at 3.7 {angstrom} (unlike phytochelatins with predominantly Cu-S coordination and short Cu-Cu interactions at 2.7 {angstrom}). Cu EXAFS of roots and leaves also vary depending on the level of heavy metal contamination in the environment from which the various creosote samples were obtained. In contrast, Pb XANES data of roots and leaves of creosote collected from different contaminated sites indicate no difference in valence states or ligand coordination.

  6. X-ray absorption spectroscopy of LiBF 4 in propylene carbonate. A model lithium ion battery electrolyte

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

    Smith, Jacob W.; Lam, Royce K.; Sheardy, Alex T.; Shih, Orion; Rizzuto, Anthony M.; Borodin, Oleg; Harris, Stephen J.; Prendergast, David; Saykally, Richard J.

    2014-08-20

    Since their introduction into the commercial marketplace in 1991, lithium ion batteries have become increasingly ubiquitous in portable technology. Nevertheless, improvements to existing battery technology are necessary to expand their utility for larger-scale applications, such as electric vehicles. Advances may be realized from improvements to the liquid electrolyte; however, current understanding of the liquid structure and properties remains incomplete. X-ray absorption spectroscopy of solutions of LiBF4 in propylene carbonate (PC), interpreted using first-principles electronic structure calculations within the eXcited electron and Core Hole (XCH) approximation, yields new insight into the solvation structure of the Li+ ion in this model electrolyte.more » By generating linear combinations of the computed spectra of Li+-associating and free PC molecules and comparing to the experimental spectrum, we find a Li+–solvent interaction number of 4.5. This result suggests that computational models of lithium ion battery electrolytes should move beyond tetrahedral coordination structures.« less

  7. Topographical and Chemical Imaging of a Phase Separated Polymer Using a Combined Atomic Force Microscopy/Infrared Spectroscopy/Mass Spectrometry Platform

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

    Tai, Tamin; Karácsony, Orsolya; Bocharova, Vera; Van Berkel, Gary J.; Kertesz, Vilmos

    2016-02-18

    This article describes how the use of a hybrid atomic force microscopy/infrared spectroscopy/mass spectrometry imaging platform was demonstrated for the acquisition and correlation of nanoscale sample surface topography and chemical images based on infrared spectroscopy and mass spectrometry.

  8. Spectroscopy of Supercapacitor Electrodes In Operando

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

    Spectroscopy of Supercapacitor Electrodes In Operando Spectroscopy of Supercapacitor Electrodes In Operando Print Wednesday, 27 May 2015 00:00 Future technology will require energy storage systems that have much larger storage capability, rapid charge/discharge cycling, and improved endurance. Progress in these areas demands a more complete understanding of the processes involved in energy storage, from the atomic scale to the device level. Now, using soft x-ray absorption spectroscopy (XAS)

  9. Complexation of Lactate with Nd(III) and Eu(III) at Variable Temperatures: Studies by Potentiometry, Microcalorimetry, Optical Absorption and Luminescence Spectroscopy

    SciTech Connect (OSTI)

    Tian, Guoxin; Martin, Leigh R.; Rao, Linfeng

    2010-10-01

    Complexation of neodymium(III) and europium(III) with lactate was studied at variable temperatures by potentiometry, absorption spectrophotometry, luminescence spectroscopy and microcalorimetry. Stability constants of three successive lactate complexes (ML{sup 2+}, ML{sup 2+} and ML{sub 3}(aq), where M stands for Nd and Eu, and L stands for lactate) at 10, 25, 40, 55 and 70 C were determined. The enthalpies of complexation at 25 C were determined by microcalorimetry. Thermodynamic data show that the complexation of trivalent lanthanides (Nd{sup 3+} and Eu{sup 3+}) with lactate is exothermic, and the complexation becomes weaker at higher temperatures. Results from optical absorption and luminescence spectroscopy suggest that the complexes are inner-sphere chelate complexes in which the protonated {alpha}-hydroxyl group of lactate participates in the complexation.

  10. Total Absorption Spectroscopy Study of ⁹²Rb Decay: A Major Contributor to Reactor Antineutrino Spectrum Shape

    SciTech Connect (OSTI)

    Sonzogni, A.; Zakari-Issoufou, A. -A.; Fallot, M.; Porta, A.; Algora, A.; Tain, J. L.; Valencia, E.; Rice, S.; Bui, V. M.; Cormon, S.; Estienne, M.; Agramunt, J.; Aysto, J.; Bowry, M.; Briz Monago, J. A.; Caballero-Folch, R.; Cano-Ott, D.; Cucoanes, A.; Eloma, V.; Estvez, E.; Farrelly, G. F.; Garcia, A.; Gelletly, W.; Gomez-Hornillos, M. B.; Gorlychev, V.; Hakala, J.; Jokinen, A.; Jordan, M. D.; Kankainen, A.; Kondev, F. G.; Martinez, T.; Mendoza, E.; Molina, F.; Moore, I.; Perez, A.; Podolyak, Zs.; Penttil, H.; Regan, P. H.; Shiba, T.; Rissanen, J.; Rubio, B.; Weber, C.

    2015-03-09

    The accurate determination of the emitted reactor antineutrino flux is still a major challenge for actual and future neutrino experiments at reactors, especially after the evidence of a disagreement between the measured antineutrino energy spectrum by Double Chooz, Daya Bay, and Reno and calculated antineutrino spectra obtained from the conversion of the unique integral beta spectra measured at the ILL reactor. Using nuclear data to compute reactor antineutrino spectra may help understanding this bias, with the study of the underlying nuclear physics. Summation calculations allow identifying a list of nuclei that contribute importantly to the antineutrino energy spectra emitted after the fission of ²³⁹,²⁴¹Pu and ²³⁵,²³⁸U, and whose beta decay properties might deserve new measurements. Among these nuclei, ⁹²Rb exhausts by itself about 16% of of the antineutrino energy spectrum emitted by Pressurized Water Reactors in the 5 to 8 MeV range. In this Letter, we report new Total Absorption Spectroscopy (TAS) results for this important contributor. The obtained beta feeding from ⁹²Rb shows beta intensity unobserved before in the 4.5 to 5.5 MeV energy region and gives a ground state to ground state branch of 87.5 % ± 3%. These new data induce a dramatic change in recent summation calculations where a 51% GS to GS branch was considered for ⁹²Rb, increasing the summation antineutrino spectrum in the region nearby the observed bias.The new data still have an important impact on other summation calculations in which more recent data were considered

  11. CHARACTERIZING THE CIRCUMGALACTIC MEDIUM OF NEARBY GALAXIES WITH HST/COS AND HST/STIS ABSORPTION-LINE SPECTROSCOPY

    SciTech Connect (OSTI)

    Stocke, John T.; Keeney, Brian A.; Danforth, Charles W.; Shull, J. Michael; Froning, Cynthia S.; Green, James C.; Penton, Steven V. [Center for Astrophysics and Space Astronomy, Department of Astrophysical and Planetary Sciences, University of Colorado, 389 UCB, Boulder, CO 80309 (United States)] [Center for Astrophysics and Space Astronomy, Department of Astrophysical and Planetary Sciences, University of Colorado, 389 UCB, Boulder, CO 80309 (United States); Savage, Blair D., E-mail: john.stocke@colorado.edu [Department of Astronomy, University of Wisconsin, Madison, WI 53706 (United States)

    2013-02-15

    The circumgalactic medium (CGM) of late-type galaxies is characterized using UV spectroscopy of 11 targeted QSO/galaxy pairs at z {<=} 0.02 with the Hubble Space Telescope Cosmic Origins Spectrograph (COS) and {approx}60 serendipitous absorber/galaxy pairs at z {<=} 0.2 with the Space Telescope Imaging Spectrograph. CGM warm cloud properties are derived, including volume filling factors of 3%-5%, cloud sizes of 0.1-30 kpc, masses of 10-10{sup 8} M {sub Sun }, and metallicities of {approx}0.1-1 Z {sub Sun }. Almost all warm CGM clouds within 0.5 R {sub vir} are metal-bearing and many have velocities consistent with being bound, 'galactic fountain' clouds. For galaxies with L {approx}> 0.1 L*, the total mass in these warm CGM clouds approaches 10{sup 10} M {sub Sun }, {approx}10%-15% of the total baryons in massive spirals and comparable to the baryons in their parent galaxy disks. This leaves {approx}> 50% of massive spiral-galaxy baryons 'missing'. Dwarfs (<0.1 L*) have smaller area covering factors and warm CGM masses ({<=}5% baryon fraction), suggesting that many of their warm clouds escape. Constant warm cloud internal pressures as a function of impact parameter (P/k {approx} 10 cm{sup -3} K) support the inference that previous COS detections of broad, shallow O VI and Ly{alpha} absorptions are of an extensive ({approx}400-600 kpc), hot (T Almost-Equal-To 10{sup 6} K), intra-cloud gas which is very massive ({>=}10{sup 11} M {sub Sun }). While the warm CGM clouds cannot account for all the 'missing baryons' in spirals, the hot intra-group gas can, and could account for {approx}20% of the cosmic baryon census at z {approx} 0 if this hot gas is ubiquitous among spiral groups.

  12. Total Absorption Spectroscopy Study of ⁹²Rb Decay: A Major Contributor to Reactor Antineutrino Spectrum Shape

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

    Sonzogni, A.; Zakari-Issoufou, A. -A.; Fallot, M.; Porta, A.; Algora, A.; Tain, J. L.; Valencia, E.; Rice, S.; Bui, V. M.; Cormon, S.; et al

    2015-03-09

    The accurate determination of the emitted reactor antineutrino flux is still a major challenge for actual and future neutrino experiments at reactors, especially after the evidence of a disagreement between the measured antineutrino energy spectrum by Double Chooz, Daya Bay, and Reno and calculated antineutrino spectra obtained from the conversion of the unique integral beta spectra measured at the ILL reactor. Using nuclear data to compute reactor antineutrino spectra may help understanding this bias, with the study of the underlying nuclear physics. Summation calculations allow identifying a list of nuclei that contribute importantly to the antineutrino energy spectra emitted aftermore » the fission of ²³⁹,²⁴¹Pu and ²³⁵,²³⁸U, and whose beta decay properties might deserve new measurements. Among these nuclei, ⁹²Rb exhausts by itself about 16% of of the antineutrino energy spectrum emitted by Pressurized Water Reactors in the 5 to 8 MeV range. In this Letter, we report new Total Absorption Spectroscopy (TAS) results for this important contributor. The obtained beta feeding from ⁹²Rb shows beta intensity unobserved before in the 4.5 to 5.5 MeV energy region and gives a ground state to ground state branch of 87.5 % ± 3%. These new data induce a dramatic change in recent summation calculations where a 51% GS to GS branch was considered for ⁹²Rb, increasing the summation antineutrino spectrum in the region nearby the observed bias.The new data still have an important impact on other summation calculations in which more recent data were considered« less

  13. First calibration measurements of an FTIR absorption spectroscopy system for liquid hydrogen isotopologues for the isotope separation system of fusion power plants

    SciTech Connect (OSTI)

    Groessle, R.; Beck, A.; Bornschein, B.; Fischer, S.; Kraus, A.; Mirz, S.; Rupp, S.

    2015-03-15

    Fusion facilities like ITER and DEMO will circulate huge amounts of deuterium and tritium in their fuel cycle with an estimated throughput of kg per hour. One important capability of these fuel cycles is to separate the hydrogen isotopologues (H{sub 2}, D{sub 2}, T{sub 2}, HD, HT, DT). For this purpose the Isotope Separation System (ISS), using cryogenic distillation, as part of the Tritium Enrichment Test Assembly (TRENTA) is under development at Tritium Laboratory Karlsruhe. Fourier transform infrared absorption spectroscopy (FTIR) has been selected to prove its capability for online monitoring of the tritium concentration in the liquid phase at the bottom of the distillation column of the ISS. The actual research-development work is focusing on the calibration of such a system. Two major issues are the identification of appropriate absorption lines and their dependence on the isotopic concentrations and composition. For this purpose the Tritium Absorption IR spectroscopy experiment has been set up as an extension of TRENTA. For calibration a Raman spectroscopy system is used. First measurements, with equilibrated mixtures of H{sub 2}, D{sub 2} and HD demonstrate that FTIR can be used for quantitative analysis of liquid hydro-gen isotopologues and reveal a nonlinear dependence of the integrated absorbance from the D{sub 2} concentration in the second vibrational branch of D{sub 2} FTIR spectra. (authors)

  14. In situ calibration of inductively coupled plasma-atomic emission and mass spectroscopy

    DOE Patents [OSTI]

    Braymen, Steven D.

    1996-06-11

    A method and apparatus for in situ addition calibration of an inductively coupled plasma atomic emission spectrometer or mass spectrometer using a precision gas metering valve to introduce a volatile calibration gas of an element of interest directly into an aerosol particle stream. The present situ calibration technique is suitable for various remote, on-site sampling systems such as laser ablation or nebulization.

  15. Atomic force microscope with combined FTIR-Raman spectroscopy having a micro thermal analyzer

    DOE Patents [OSTI]

    Fink, Samuel D.; Fondeur, Fernando F.

    2011-10-18

    An atomic force microscope is provided that includes a micro thermal analyzer with a tip. The micro thermal analyzer is configured for obtaining topographical data from a sample. A raman spectrometer is included and is configured for use in obtaining chemical data from the sample.

  16. Spectroscopy

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

    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,...

  17. In situ calibration of inductively coupled plasma-atomic emission and mass spectroscopy

    DOE Patents [OSTI]

    Braymen, S.D.

    1996-06-11

    A method and apparatus are disclosed for in situ addition calibration of an inductively coupled plasma atomic emission spectrometer or mass spectrometer using a precision gas metering valve to introduce a volatile calibration gas of an element of interest directly into an aerosol particle stream. The present in situ calibration technique is suitable for various remote, on-site sampling systems such as laser ablation or nebulization. 5 figs.

  18. Phase-dependent high refractive index without absorption in a four-level inverted-Y atomic system

    SciTech Connect (OSTI)

    Zhi-Qiang Zeng; Fu-Ti Liu; Yu-Ping Wang; Zeng-Hui Gao

    2015-01-31

    We consider a closed four-level inverted-Y system in the presence and the absence of a microwave field. It is found that due to the quantum coherence between the two lower levels, either induced by the spontaneous decay or by the microwave field, the refraction – absorption properties of the system can be modulated by controlling the relative phase of the applied fields in both driven ways. In particular, by properly setting the values of the relative phase, the desirable high index of refraction without absorption can be achieved. (nonlinear optical phenomena)

  19. Quantitative broadband absorption and scattering spectroscopy in turbid media by combined frequency-domain and steady state methodologies

    DOE Patents [OSTI]

    Tromberg, Bruce J.; Berger, Andrew J.; Cerussi, Albert E.; Bevilacqua, Frederic; Jakubowski, Dorota

    2008-09-23

    A technique for measuring broadband near-infrared absorption spectra of turbid media that uses a combination of frequency-domain and steady-state reflectance methods. Most of the wavelength coverage is provided by a white-light steady-state measurement, whereas the frequency-domain data are acquired at a few selected wavelengths. Coefficients of absorption and reduced scattering derived from the frequency-domain data are used to calibrate the intensity of the steady-state measurements and to determine the reduced scattering coefficient at all wavelengths in the spectral window of interest. The absorption coefficient spectrum is determined by comparing the steady-state reflectance values with the predictions of diffusion theory, wavelength by wavelength. Absorption spectra of a turbid phantom and of human breast tissue in vivo, derived with the combined frequency-domain and steady-state technique, agree well with expected reference values.

  20. Hybrid interferometric/dispersive atomic spectroscopy of laser-induced uranium plasma

    SciTech Connect (OSTI)

    Morgan, Phyllis K.; Scott, Jill R.; Jovanovic, Igor

    2015-12-19

    An established optical emission spectroscopy technique, laser-induced breakdown spectroscopy (LIBS), holds promise for detection and rapid analysis of elements relevant for nuclear safeguards, nonproliferation, and nuclear power, including the measurement of isotope ratios. One such important application of LIBS is the measurement of uranium enrichment (235U/238U), which requires high spectral resolution (e.g., 25 pm for the 424.4 nm U II line). High-resolution dispersive spectrometers necessary for such measurements are typically bulky and expensive. We demonstrate the use of an alternative measurement approach, which is based on an inexpensive and compact Fabry–Perot etalon integrated with a low to moderate resolution Czerny–Turner spectrometer, to achieve the resolution needed for isotope selectivity of LIBS of uranium in ambient air. Furthermore, spectral line widths of ~ 10 pm have been measured at a center wavelength 424.437 nm, clearly discriminating the natural from the highly enriched uranium.

  1. Hybrid interferometric/dispersive atomic spectroscopy of laser-induced uranium plasma

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

    Morgan, Phyllis K.; Scott, Jill R.; Jovanovic, Igor

    2015-12-19

    An established optical emission spectroscopy technique, laser-induced breakdown spectroscopy (LIBS), holds promise for detection and rapid analysis of elements relevant for nuclear safeguards, nonproliferation, and nuclear power, including the measurement of isotope ratios. One such important application of LIBS is the measurement of uranium enrichment (235U/238U), which requires high spectral resolution (e.g., 25 pm for the 424.4 nm U II line). High-resolution dispersive spectrometers necessary for such measurements are typically bulky and expensive. We demonstrate the use of an alternative measurement approach, which is based on an inexpensive and compact Fabry–Perot etalon integrated with a low to moderate resolution Czerny–Turnermore » spectrometer, to achieve the resolution needed for isotope selectivity of LIBS of uranium in ambient air. Furthermore, spectral line widths of ~ 10 pm have been measured at a center wavelength 424.437 nm, clearly discriminating the natural from the highly enriched uranium.« less

  2. Scanning tunneling spectroscopy of a magnetic atom on graphene in the Kondo regime

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

    Zhuang, Huai -Bin; Sun, Qing -feng; Xie, X. C.

    2009-06-23

    In this study, the Kondo effect in the system consisting of a magnetic adatom on the graphene is studied. By using the non-equilibrium Green function method with the slave-boson mean field approximation, the local density of state (LDOS) and the conductance are calculated. For a doped graphene, the Kondo phase is present at all time. Surprisingly, two kinds of Kondo regimes are revealed. But for the undoped graphene, the Kondo phase only exists if the adatom’s energy level is beyond a critical value. The conductance is similar to the LDOS, thus, the Kondo peak in the LDOS can be observedmore » with the scanning tunneling spectroscopy. In addition, in the presence of a direct coupling between the STM tip and the graphene, the conductance may be dramatically enhanced, depending on the coupling site.« less

  3. Fe-implanted 6H-SiC: Direct evidence of Fe{sub 3}Si nanoparticles observed by atom probe tomography and {sup 57}Fe Mssbauer spectroscopy

    SciTech Connect (OSTI)

    Diallo, M. L.; Fnidiki, A. Lard, R.; Cuvilly, F.; Blum, I.; Lechevallier, L.; Debelle, A.; Thom, L.; Viret, M.; Marteau, M.; Eyidi, D.; Declmy, A.

    2015-05-14

    In order to understand ferromagnetic ordering in SiC-based diluted magnetic semiconductors, Fe-implanted 6H-SiC subsequently annealed was studied by Atom Probe Tomography, {sup 57}Fe Mssbauer spectroscopy and SQUID magnetometry. Thanks to its 3D imaging capabilities at the atomic scale, Atom Probe Tomography appears as the most suitable technique to investigate the Fe distribution in the 6H-SiC host semiconductor and to evidence secondary phases. This study definitely evidences the formation of Fe{sub 3}Si nano-sized clusters after annealing. These clusters are unambiguously responsible for the main part of the magnetic properties observed in the annealed samples.

  4. X-ray absorption spectroscopy of aluminum z-pinch plasma with tungsten backlighter planar wire array source

    SciTech Connect (OSTI)

    Osborne, G. C.; Kantsyrev, V. L.; Safronova, A. S.; Esaulov, A. A.; Weller, M. E.; Shrestha, I.; Shlyaptseva, V. V.; Ouart, N. D.

    2012-10-15

    Absorption features from K-shell aluminum z-pinch plasmas have recently been studied on Zebra, the 1.7 MA pulse power generator at the Nevada Terawatt Facility. In particular, tungsten plasma has been used as a semi-backlighter source in the generation of aluminum K-shell absorption spectra by placing a single Al wire at or near the end of a single planar W array. All spectroscopic experimental results were recorded using a time-integrated, spatially resolved convex potassium hydrogen phthalate (KAP) crystal spectrometer. Other diagnostics used to study these plasmas included x-ray detectors, optical imaging, laser shadowgraphy, and time-gated and time-integrated x-ray pinhole imagers. Through comparisons with previous publications, Al K-shell absorption lines are shown to be from much lower electron temperature ({approx}10-40 eV) plasmas than emission spectra ({approx}350-500 eV).

  5. Spectroscopy of Supercapacitor Electrodes In Operando

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

    Spectroscopy of Supercapacitor Electrodes In Operando Print Future technology will require energy storage systems that have much larger storage capability, rapid charge/discharge cycling, and improved endurance. Progress in these areas demands a more complete understanding of the processes involved in energy storage, from the atomic scale to the device level. Now, using soft x-ray absorption spectroscopy (XAS) under operating conditions ("in operando"), researchers have found that the

  6. Spectroscopy of Supercapacitor Electrodes In Operando

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

    Spectroscopy of Supercapacitor Electrodes In Operando Print Future technology will require energy storage systems that have much larger storage capability, rapid charge/discharge cycling, and improved endurance. Progress in these areas demands a more complete understanding of the processes involved in energy storage, from the atomic scale to the device level. Now, using soft x-ray absorption spectroscopy (XAS) under operating conditions ("in operando"), researchers have found that the

  7. Spectroscopy of Supercapacitor Electrodes In Operando

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

    Spectroscopy of Supercapacitor Electrodes In Operando Print Future technology will require energy storage systems that have much larger storage capability, rapid charge/discharge cycling, and improved endurance. Progress in these areas demands a more complete understanding of the processes involved in energy storage, from the atomic scale to the device level. Now, using soft x-ray absorption spectroscopy (XAS) under operating conditions ("in operando"), researchers have found that the

  8. Spectroscopy of Supercapacitor Electrodes In Operando

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

    Spectroscopy of Supercapacitor Electrodes In Operando Print Future technology will require energy storage systems that have much larger storage capability, rapid charge/discharge cycling, and improved endurance. Progress in these areas demands a more complete understanding of the processes involved in energy storage, from the atomic scale to the device level. Now, using soft x-ray absorption spectroscopy (XAS) under operating conditions ("in operando"), researchers have found that the

  9. Spectroscopy of Supercapacitor Electrodes In Operando

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

    Spectroscopy of Supercapacitor Electrodes In Operando Print Future technology will require energy storage systems that have much larger storage capability, rapid charge/discharge cycling, and improved endurance. Progress in these areas demands a more complete understanding of the processes involved in energy storage, from the atomic scale to the device level. Now, using soft x-ray absorption spectroscopy (XAS) under operating conditions ("in operando"), researchers have found that the

  10. Spectroscopy of Supercapacitor Electrodes In Operando

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

    Spectroscopy of Supercapacitor Electrodes In Operando Print Future technology will require energy storage systems that have much larger storage capability, rapid charge/discharge cycling, and improved endurance. Progress in these areas demands a more complete understanding of the processes involved in energy storage, from the atomic scale to the device level. Now, using soft x-ray absorption spectroscopy (XAS) under operating conditions ("in operando"), researchers have found that the

  11. A laboratory-based hard x-ray monochromator for high-resolution x-ray emission spectroscopy and x-ray absorption near edge structure measurements

    SciTech Connect (OSTI)

    Seidler, G. T. Mortensen, D. R.; Remesnik, A. J.; Pacold, J. I.; Ball, N. A.; Barry, N.; Styczinski, M.; Hoidn, O. R.

    2014-11-15

    We report the development of a laboratory-based Rowland-circle monochromator that incorporates a low power x-ray (bremsstrahlung) tube source, a spherically bent crystal analyzer, and an energy-resolving solid-state detector. This relatively inexpensive, introductory level instrument achieves 1-eV energy resolution for photon energies of ∼5 keV to ∼10 keV while also demonstrating a net efficiency previously seen only in laboratory monochromators having much coarser energy resolution. Despite the use of only a compact, air-cooled 10 W x-ray tube, we find count rates for nonresonant x-ray emission spectroscopy comparable to those achieved at monochromatized spectroscopy beamlines at synchrotron light sources. For x-ray absorption near edge structure, the monochromatized flux is small (due to the use of a low-powered x-ray generator) but still useful for routine transmission-mode studies of concentrated samples. These results indicate that upgrading to a standard commercial high-power line-focused x-ray tube or rotating anode x-ray generator would result in monochromatized fluxes of order 10{sup 6}–10{sup 7} photons/s with no loss in energy resolution. This work establishes core technical capabilities for a rejuvenation of laboratory-based hard x-ray spectroscopies that could have special relevance for contemporary research on catalytic or electrical energy storage systems using transition-metal, lanthanide, or noble-metal active species.

  12. Setup for in situ investigation of gases and gas/solid interfaces by soft x-ray emission and absorption spectroscopy

    SciTech Connect (OSTI)

    Benkert, A. E-mail: l.weinhardt@kit.edu; Blum, M.; Advanced Light Source, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720 ; Meyer, F.; Wilks, R. G.; Yang, W.; Bär, M.; Solar Energy Research, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Hahn-Meitner-Platz 1, 14109 Berlin; Insitut für Physik und Chemie, Brandenburgische Technische Universität Cottbus-Senftenberg, Konrad-Wachsmann-Allee 1, 03046 Cottbus ; and others

    2014-01-15

    We present a novel gas cell designed to study the electronic structure of gases and gas/solid interfaces using soft x-ray emission and absorption spectroscopies. In this cell, the sample gas is separated from the vacuum of the analysis chamber by a thin window membrane, allowing in situ measurements under atmospheric pressure. The temperature of the gas can be regulated from room temperature up to approximately 600 °C. To avoid beam damage, a constant mass flow can be maintained to continuously refresh the gaseous sample. Furthermore, the gas cell provides space for solid-state samples, allowing to study the gas/solid interface for surface catalytic reactions at elevated temperatures. To demonstrate the capabilities of the cell, we have investigated a TiO{sub 2} sample behind a mixture of N{sub 2} and He gas at atmospheric pressure.

  13. An in situ sample environment reaction cell for spatially resolved x-ray absorption spectroscopy studies of powders and small structured reactors

    SciTech Connect (OSTI)

    Zhang, Chu; Gustafson, Johan; Merte, Lindsay R.; Evertsson, Jonas; Norén, Katarina; Carlson, Stefan; Svensson, Håkan; Carlsson, Per-Anders

    2015-03-15

    An easy-to-use sample environment reaction cell for X-ray based in situ studies of powders and small structured samples, e.g., powder, pellet, and monolith catalysts, is described. The design of the cell allows for flexible use of appropriate X-ray transparent windows, shielding the sample from ambient conditions, such that incident X-ray energies as low as 3 keV can be used. Thus, in situ X-ray absorption spectroscopy (XAS) measurements in either transmission or fluorescence mode are facilitated. Total gas flows up to about 500 ml{sub n}/min can be fed while the sample temperature is accurately controlled (at least) in the range of 25–500 °C. The gas feed is composed by a versatile gas-mixing system and the effluent gas flow composition is monitored with mass spectrometry (MS). These systems are described briefly. Results from simultaneous XAS/MS measurements during oxidation of carbon monoxide over a 4% Pt/Al{sub 2}O{sub 3} powder catalyst are used to illustrate the system performance in terms of transmission XAS. Also, 2.2% Pd/Al{sub 2}O{sub 3} and 2% Ag − Al{sub 2}O{sub 3} powder catalysts have been used to demonstrate X-ray absorption near-edge structure (XANES) spectroscopy in fluorescence mode. Further, a 2% Pt/Al{sub 2}O{sub 3} monolith catalyst was used ex situ for transmission XANES. The reaction cell opens for facile studies of structure-function relationships for model as well as realistic catalysts both in the form of powders, small pellets, and coated or extruded monoliths at near realistic conditions. The applicability of the cell for X-ray diffraction measurements is discussed.

  14. Portable sample preparation and analysis system for micron and sub-micron particle characterization using light scattering and absorption spectroscopy

    DOE Patents [OSTI]

    Stark, Peter C.; Zurek, Eduardo; Wheat, Jeffrey V.; Dunbar, John M.; Olivares, Jose A.; Garcia-Rubio, Luis H.; Ward, Michael D.

    2011-07-26

    There is provided a method and device for remote sampling, preparation and optical interrogation of a sample using light scattering and light absorption methods. The portable device is a filtration-based device that removes interfering background particle material from the sample matrix by segregating or filtering the chosen analyte from the sample solution or matrix while allowing the interfering background particles to be pumped out of the device. The segregated analyte is then suspended in a diluent for analysis. The device is capable of calculating an initial concentration of the analyte, as well as diluting the analyte such that reliable optical measurements can be made. Suitable analytes include cells, microorganisms, bioparticles, pathogens and diseases. Sample matrixes include biological fluids such as blood and urine, as well as environmental samples including waste water.

  15. High resolution absorption spectroscopy of exploding wire plasmas using an x-pinch x-ray source and spherically bent crystal

    SciTech Connect (OSTI)

    Knapp, P. F.; Pikuz, S. A.; Shelkovenko, T. A.; Hammer, D. A.; Hansen, S. B.

    2011-06-15

    We present here the use of absorption spectroscopy of the continuum radiation from x-pinch-produced point x-ray sources as a diagnostic to investigate the properties of aluminum plasmas created by pulsed power machines. This technique is being developed to determine the charge state, temperature, and density as a function of time and space under conditions that are inaccessible to x-ray emission spectroscopic diagnostics. The apparatus and its characterization are described, and the spectrometer dispersion, magnification, and resolution are calculated and compared with experimental results. Spectral resolution of about 5000 and spatial resolution of about 20 {mu}m are demonstrated. This spectral resolution is the highest available to date in an absorption experiment. The beneficial properties of the x-pinch x-ray source as the backlighter for this diagnostic are the small source size (<5 {mu}m), smooth continuum radiation, and short pulse duration (<0.1 ns). Results from a closely spaced (1 mm) exploding wire pair are shown and the general features are discussed.

  16. Two Keggin-type heteropolytungstates with transition metal as a central atom: Crystal structure and magnetic study with 2D-IR correlation spectroscopy

    SciTech Connect (OSTI)

    Chai, Feng [Department of Chemistry, Fuzhou University, Fuzhou 350108 (China); Chen, YiPing, E-mail: ypchen007@sina.com [Department of Chemistry, Fuzhou University, Fuzhou 350108 (China); State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002 (China); You, ZhuChai; Xia, ZeMin; Ge, SuZhi; Sun, YanQiong; Huang, BiHua [Department of Chemistry, Fuzhou University, Fuzhou 350108 (China)

    2013-06-01

    Two Keggin-type heteropolytungstates, [Co(phen)?]?[CoW??O??]9H?O 1 (phen=1,10-phenanthroline) and [Fe(phen)?]?[FeW??O??]H?OH?O 2, have been synthesized via the hydrothermal technique and characterized by single crystal X-ray diffraction analyses, IR, XPS, TG analysis, UVDRS, XRD, thermal-dependent and magnetic-dependent 2D-COS IR (two-dimensional infrared correlation spectroscopy). Crystal structure analysis reveals that the polyanions in compound 1 are linked into 3D supramolecule through hydrogen bonding interactions between lattice water molecules and terminal oxygen atoms of polyanion units, and [Co(phen)?]? cations distributed in the polyanion framework with many hydrogen bonding interactions. The XPS spectra indicate that all the Co atoms in 1 are +2 oxidation state, the Fe atoms in 2 existing with +2 and +3 mixed oxidation states. - Graphical abstract: The magnetic-dependent synchronous 2D correlation IR spectra of 1 (a), 2 (b) over 050 mT in the range of 6001000 cm?, the obvious response indicate two Keggin polyanions skeleton susceptible to applied magnetic field. Highlights: Two Keggin-type heteropolytungstates with transition metal as a central atom has been obtained. Compound 1 forms into 3D supramolecular architecture through hydrogen bonding between water molecules and polyanions. Magnetic-dependent 2D-IR correlation spectroscopy was introduced to discuss the magnetism of polyoxometalate.

  17. Direct speciation analysis of arsenic in sub-cellular compartments using micro-X-ray absorption spectroscopy

    SciTech Connect (OSTI)

    Bacquart, Thomas; Deves, Guillaume; Ortega, Richard

    2010-07-15

    Identification of arsenic chemical species at a sub-cellular level is a key to understanding the mechanisms involved in arsenic toxicology and antitumor pharmacology. When performed with a microbeam, X-ray absorption near-edge structure ({mu}-XANES) enables the direct speciation analysis of arsenic in sub-cellular compartments avoiding cell fractionation and other preparation steps that might modify the chemical species. This methodology couples tracking of cellular organelles in a single cell by confocal or epifluorescence microscopy with local analysis of chemical species by {mu}-XANES. Here we report the results obtained with a {mu}-XANES experimental setup based on Kirkpatrick-Baez X-ray focusing optics that maintains high flux of incoming radiation (>10{sup 11} ph/s) at micrometric spatial resolution (1.5x4.0 {mu}m{sup 2}). This original experimental setup enabled the direct speciation analysis of arsenic in sub-cellular organelles with a 10{sup -15} g detection limit. {mu}-XANES shows that inorganic arsenite, As(OH){sub 3}, is the main form of arsenic in the cytosol, nucleus, and mitochondrial network of cultured cancer cells exposed to As{sub 2}O{sub 3}. On the other hand, a predominance of As(III) species is observed in HepG2 cells exposed to As(OH){sub 3} with, in some cases, oxidation to a pentavalent form in nuclear structures of HepG2 cells. The observation of intra-nuclear mixed redox states suggests an inter-individual variability in a cell population that can only be evidenced with direct sub-cellular speciation analysis.

  18. Correlation between Active Center Structure and Enhanced Dioxygen Binding in Co(salen) Nanoparticles: Characterization by In Situ Infrared, Raman, and X-ray Absorption Spectroscopies

    SciTech Connect (OSTI)

    Johnson,C.; Long, B.; Nguyen, J.; Day, V.; Borovik, A.; Subramaniam, B.; Guzman, J.

    2008-01-01

    The structure and ligand environment of Co(salen) nanoparticles and unprocessed Co(salen) have been determined by the combined application of infrared, Raman, X-ray absorption near edge structure (XANES), and extended X-ray absorption fine structure (EXAFS) spectroscopies, and X-ray diffraction (XRD) experiments before and during interaction with O2. The Co(salen) nanoparticles were prepared by the precipitation with compressed antisolvent (PCA) technique using commercially obtained Co(salen) [denoted as unprocessed Co(salen)] as the parent compound. The unprocessed Co(salen) particles exist as dimer species with a square-pyramidal coordination geometry that display no measurable O2 binding at room temperature. In sharp contrast, the Co(salen) nanoparticles show near-stoichiometric O2 adsorption, as demonstrated by microbalance gas binding experiments. The spectroscopy results indicate the presence of CoII centers with distorted tetrahedral geometry in the Co(salen) nanoparticles with no evidence of metallic Co clusters, confirmed by the lack of Co-Co contributions at bonding distances in the EXAFS spectra and the presence of characteristic features of CoII in the XANES spectra. The EXAFS data also indicate that there are on average two Co-N and two Co-O bonds with a distance of 1.81 {+-} 0.02 and 1.90 {+-} 0.02 Angstroms, respectively, consistent with typical metal salen structures. Upon O2 binding on the Co(salen) nanoparticles, the XANES results indicate oxidation of the CoII to CoIII, consistent with the vibrational data showing new bands associated with oxygen species bonded to Co centers and the increase in the oxygen coordination number from 1.8 to 2.9 in the EXAFS data. The results indicate that the enhanced O2 binding properties of Co(salen) nanoparticles are related to the unique distorted tetrahedral geometry, which is not observed in the unprocessed samples that contain mainly dimers with square planar geometry. The results presented here provide a

  19. Laser produced plasma diagnostics by cavity ringdown spectroscopy and applications

    SciTech Connect (OSTI)

    Milosevic, S.

    2012-05-25

    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.

  20. X-ray absorption spectroscopy of LiBF 4 in propylene carbonate. A model lithium ion battery electrolyte

    SciTech Connect (OSTI)

    Smith, Jacob W.; Lam, Royce K.; Sheardy, Alex T.; Shih, Orion; Rizzuto, Anthony M.; Borodin, Oleg; Harris, Stephen J.; Prendergast, David; Saykally, Richard J.

    2014-08-20

    Since their introduction into the commercial marketplace in 1991, lithium ion batteries have become increasingly ubiquitous in portable technology. Nevertheless, improvements to existing battery technology are necessary to expand their utility for larger-scale applications, such as electric vehicles. Advances may be realized from improvements to the liquid electrolyte; however, current understanding of the liquid structure and properties remains incomplete. X-ray absorption spectroscopy of solutions of LiBF4 in propylene carbonate (PC), interpreted using first-principles electronic structure calculations within the eXcited electron and Core Hole (XCH) approximation, yields new insight into the solvation structure of the Li+ ion in this model electrolyte. By generating linear combinations of the computed spectra of Li+-associating and free PC molecules and comparing to the experimental spectrum, we find a Li+–solvent interaction number of 4.5. This result suggests that computational models of lithium ion battery electrolytes should move beyond tetrahedral coordination structures.

  1. Time-Resolved Quantitative Measurement of OH HO2 and CH2O in Fuel Oxidation Reactions by High Resolution IR Absorption Spectroscopy.

    SciTech Connect (OSTI)

    Huang, Haifeng; Rotavera, Brandon; Taatjes, Craig A.

    2014-08-01

    Combined with a Herriott-type multi-pass slow flow reactor, high-resolution differential direct absorption spectroscopy has been used to probe, in situ and quantitatively, hydroxyl (OH), hydroperoxy (HO 2 ) and formaldehyde (CH 2 O) molecules in fuel oxidation reactions in the reactor, with a time resolution of about 1 micro-second. While OH and CH 2 O are probed in the mid-infrared (MIR) region near 2870nm and 3574nm respectively, HO 2 can be probed in both regions: near-infrared (NIR) at 1509nm and MIR at 2870nm. Typical sensitivities are on the order of 10 10 - 10 11 molecule cm -3 for OH at 2870nm, 10 11 molecule cm -3 for HO 2 at 1509nm, and 10 11 molecule cm -3 for CH 2 O at 3574nm. Measurements of multiple important intermediates (OH and HO 2 ) and product (CH 2 O) facilitate to understand and further validate chemical mechanisms of fuel oxidation chemistry.

  2. Dissolution of thin iron oxide films used as models for iron passive films studied by in situ X-ray absorption near-edge spectroscopy

    SciTech Connect (OSTI)

    Virtanen, S; Schmuki, P.; Davenport, A.J.; Vitus, C.M.

    1997-01-01

    This paper reports results from X-ray absorption near-edge spectroscopy (XANES) studies during polarization of thin sputter-deposited iron oxide films in acidic solutions. The dissolution rate of iron oxides in acidic solutions was found to be strongly increased by the presence of Fe{sup 2+} in the oxide. During anodic polarization in acidic solutions, it is found that dissolution is accelerated by chloride anions in comparison with sulfates. In HCl solutions of increasing concentration, not only does the pH decrease, but also the increasing chloride concentration accelerates dissolution. On the other hand, the dissolution rate in sulfuric acid does not depend on the sulfate (bisulfate) concentration. During anodic polarization, the dissolution rate is fairly independent of the potential, except at very high anodic potentials, and the XANES spectra reveal no changes in the average oxide valence during anodic polarization. Thus the dissolution that takes place is mostly chemical rather than electrochemical. During cathodic polarization, the dissolution rate is independent of the anion in the electrolyte. The findings are interpreted in terms of the negative surface charge of n-type oxides at potentials lower than the flatband potential, retarding anion adsorption on the surface. Hence it is suggested that the detrimental role of chloride anions on the stability of iron oxide films is due to a surface complexation effect. The findings and their relevance to the stability of natural passive films on iron surfaces are discussed.

  3. Probing the f-state configuration of URu2Si2 with U LIII-edge resonant x-ray absorption spectroscopy

    SciTech Connect (OSTI)

    Medling, S. A.; Booth, C. H.; Tobin, J. G.; Baumbach, R. E.; Bauer, E. D.; Sokaras, D.; Nordlund, D.; Weng, T. C.

    2015-09-05

    It has often been said that the most interesting ph- syics occurs when competing interactions are of nearly the same magnitude. Such a situation is surely oc- curing at URu2Si2’s so-called “hidden-order transition”, which garners its name from the missing entropy at a 17.5 K phase transition relative to that expected for a conventional antiferromagnetic phase transition, de- spite the presence of only a very small ordered mag- netic moment.? Despite this discrepancy being identi- fied in 1985, the identification of the order parameter remains elusive, although progress toward understand- ing this transition has been steady since that time, and URu2Si2 remains an important research subject today.? The work described below provides measures of the 5f orbital occupancy and itinerancy using resonant x-ray emission spectroscopy (RXES) at the U LIII absorption edge and measuring U L 1 emission that potentially acts as a dividing line between different classes of “hidden- order” theories.

  4. CW EC-QCL-based sensor for simultaneous detection of H2O, HDO, N2O and CH4 using multi-pass absorption spectroscopy

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

    Yu, Yajun; Sanchez, Nancy P.; Griffin, Robert J.; Tittel, Frank K.

    2016-05-03

    A sensor system based on a continuous wave, external-cavity quantum-cascade laser (CW EC-QCL) was demonstrated for simultaneous detection of atmospheric H2O, HDO, N2O and CH4 using a compact, dense pattern multi-pass gas cell with an effective path-length of 57.6 m. The EC-QCL with a mode-hop-free spectral range of 1225-1285 cm-1 operating at similar to 7.8 mu m was scanned covering four neighboring absorption lines, for H2O at 1281.161 cm-1, HDO at 1281.455 cm-1, N2O at 1281.53 cm-1 and CH4 at 1281.61 cm-1. A first-harmonic-normalized wavelength modulation spectroscopy with second-harmonic detection (WMS-2f/1f) strategy was employed for data processing. An Allan-Werle deviationmore » analysis indicated that minimum detection limits of 1.77 ppmv for H2O, 3.92 ppbv for HDO, 1.43 ppbv for N2O, and 2.2 ppbv for CH4 were achieved with integration times of 50-s, 50-s, 100-s and 129-s, respectively. In conclusion, experimental measurements of ambient air are also reported.« less

  5. LASER ABLATION-INDUCTIVELY COUPLED PLASMA-ATOMIC EMISSION SPECTROSCOPY STUDY AT THE 222-S LABORATORY USING HOT-CELL GLOVE BOX PROTOTYPE SYSTEM

    SciTech Connect (OSTI)

    LOCKREM LL; OWENS JW; SEIDEL CM

    2009-03-26

    This report describes the installation, testing and acceptance of the Waste Treatment and Immobilization Plant procured laser ablation-inductively coupled plasma-atomic emission spectroscopy (LA-ICP-AES) system for remotely analyzing high-level waste samples in a hot cell environment. The 2005-003; ATS MP 1027, Management Plan for Waste Treatment Plant Project Work Performed by Analytical Technical Services. The APD group at the 222-S laboratory demonstrated acceptable turnaround time (TAT) and provide sufficient data to assess sensitivity, accuracy, and precision of the LA-ICP-AES method.

  6. LASER ABLATION-INDUCTIVELY COUPLED PLASMA-ATOMIC EMISSION SPECTROSCOPY STUDY AT THE 222-S LABORATORY USING HOT-CELL GLOVE BOX PROTOTYPE SYSTEM

    SciTech Connect (OSTI)

    SEIDEL CM; JAIN J; OWENS JW

    2009-02-23

    This report describes the installation, testing, and acceptance of the Waste Treatment and Immobilization Plant (WTP) procured laser ablation-inductively coupled plasma-atomic emission spectroscopy (LA-ICP-AES) system for remotely analyzing high-level waste (HLW) samples in a hot cell environment. The work was completed by the Analytical Process Development (APD) group in accordance with Task Order 2005-003; ATS MP 1027, Management Plan for Waste Treatment Plant Project Work Performed by Analytical Technical Services. The APD group at the 222-S Laboratory demonstrated acceptable turnaround time (TAT) and provide sufficient data to assess sensitivity, accuracy, and precision of the LA-ICP-AES method.

  7. Ultrafast photo-induced nuclear relaxation of a conformationally disordered conjugated polymer probed with transient absorption and femtosecond stimulated Raman spectroscopies

    SciTech Connect (OSTI)

    Yu, Wenjian; Donohoo-Vallett, Paul J.; Zhou, Jiawang; Bragg, Arthur E.

    2014-07-28

    A combination of transient absorption (TAS) and femtosecond stimulated Raman (FSRS) spectroscopies were used to interrogate the photo-induced nuclear relaxation dynamics of poly(3-cyclohexyl,4-methylthiophene) (PCMT). The large difference in inter-ring dihedral angles of ground and excited-state PCMT make it an ideal candidate for studying large-amplitude vibrational relaxation associated with exciton trapping. Spectral shifting in the S{sub 1} TA spectra on sub-ps timescales (110 ± 20 and 800 ± 100 fs) is similar to spectroscopic signatures of excited-state relaxation observed with related photoexcited conjugated polymers and which have been attributed to exciton localization and a combination of resonant energy transfer and torsional relaxation, respectively. Measurements made with both techniques reveal fast PCMT S{sub 1} decay and triplet formation (τ{sub S1} = 25–32 ps), which is similar to the excited-state dynamics of short oligothiophenes and highly twisted polyconjugated molecules. On ultrafast timescales FSRS of S{sub 1} PCMT offers a new perspective on the nuclear dynamics that underlie localization of excitons in photoexcited conjugated polymers: Spectral dynamics in the C=C stretching region (1400–1600 cm{sup −1}) include a red-shift of the in-phase C=C stretching frequency, as well as a change in the relative intensity of in-phase and out-of-phase stretch intensities on a timescale of ∼100 fs. Both changes indicate an ultrafast vibrational distortion that increases the conjugation length in the region of the localized excitation and are consistent with exciton self-localization or trapping. Wavelength-dependent excited-state FSRS measurements further demonstrate that the C=C stretching frequency provides a useful spectroscopic handle for interrogating the degree of delocalization in excited conjugated polymers given the selectivity achieved via resonance enhancement.

  8. Effects of backlight structure on absorption experiments (Journal...

    Office of Scientific and Technical Information (OSTI)

    Quantitative Spectroscopy and Radiative Transfer; Journal Volume: 99 Research Org: ... Language: English Subject: 70 PLASMA PHYSICS AND FUSION TECHNOLOGY; ABSORPTION; ABSORPTION ...

  9. Energy-loss- and thickness-dependent contrast in atomic-scale electron energy-loss spectroscopy

    SciTech Connect (OSTI)

    Tan, Haiyan; Zhu, Ye; Dwyer, Christian; Xin, Huolin L.

    2014-12-31

    Atomic-scale elemental maps of materials acquired by core-loss inelastic electron scattering often exhibit an undesirable sensitivity to the unavoidable elastic scattering, making the maps counter-intuitive to interpret. Here, we present a systematic study that scrutinizes the energy-loss and sample-thickness dependence of atomic-scale elemental maps acquired using 100 keV incident electrons in a scanning transmission electron microscope. For single-crystal silicon, the balance between elastic and inelastic scattering means that maps generated from the near-threshold Si-L signal (energy loss of 99 eV) show no discernible contrast for a thickness of 0.5? (? is the electron mean-free path, here approximately 110 nm). At greater thicknesses we observe a counter-intuitive negative contrast. Only at much higher energy losses is an intuitive positive contrast gradually restored. Our quantitative analysis shows that the energy-loss at which a positive contrast is restored depends linearly on the sample thickness. This behavior is in very good agreement with our double-channeling inelastic scattering calculations. We test a recently-proposed experimental method to correct the core-loss inelastic scattering and restore an intuitive positive chemical contrast. The method is demonstrated to be reliable over a large range of energy losses and sample thicknesses. The corrected contrast for near-threshold maps is demonstrated to be (desirably) inversely proportional to sample thickness. As a result, implications for the interpretation of atomic-scale elemental maps are discussed.

  10. Energy-loss- and thickness-dependent contrast in atomic-scale electron energy-loss spectroscopy

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

    Tan, Haiyan; Zhu, Ye; Dwyer, Christian; Xin, Huolin L.

    2014-12-31

    Atomic-scale elemental maps of materials acquired by core-loss inelastic electron scattering often exhibit an undesirable sensitivity to the unavoidable elastic scattering, making the maps counter-intuitive to interpret. Here, we present a systematic study that scrutinizes the energy-loss and sample-thickness dependence of atomic-scale elemental maps acquired using 100 keV incident electrons in a scanning transmission electron microscope. For single-crystal silicon, the balance between elastic and inelastic scattering means that maps generated from the near-threshold Si-L signal (energy loss of 99 eV) show no discernible contrast for a thickness of 0.5λ (λ is the electron mean-free path, here approximately 110 nm). Atmore » greater thicknesses we observe a counter-intuitive “negative” contrast. Only at much higher energy losses is an intuitive “positive” contrast gradually restored. Our quantitative analysis shows that the energy-loss at which a positive contrast is restored depends linearly on the sample thickness. This behavior is in very good agreement with our double-channeling inelastic scattering calculations. We test a recently-proposed experimental method to correct the core-loss inelastic scattering and restore an intuitive “positive” chemical contrast. The method is demonstrated to be reliable over a large range of energy losses and sample thicknesses. The corrected contrast for near-threshold maps is demonstrated to be (desirably) inversely proportional to sample thickness. As a result, implications for the interpretation of atomic-scale elemental maps are discussed.« less

  11. Soft X-ray absorption spectroscopy of La{sub 0.7}Ca{sub 0.3}Mn{sub 1−X}Al{sub X}O{sub 3} thin films

    SciTech Connect (OSTI)

    Kumar, Manish Choudhary, R. J. Phase, D. M.

    2014-04-24

    Epitaxial thin films of rare earth manganites have generated much attention recently due to their rich phase diagram. The electronic structure of these films is playing a very crucial role and demands a fundamental understanding prior to device fabrication. We have investigated the electronic structure of La{sub 0.7}Ca{sub 0.3}Mn{sub 1−X}Al{sub X}O{sub 3} (X=0, 0.15) epitaxial thin films by soft X-ray absorption spectroscopy technique using the surface sensitive total electron yield (TEY) mode.

  12. Atomic vapor laser isotope separation process

    DOE Patents [OSTI]

    Wyeth, Richard W.; Paisner, Jeffrey A.; Story, Thomas

    1990-01-01

    A laser spectroscopy system is utilized in an atomic vapor laser isotope separation process. The system determines spectral components of an atomic vapor utilizing a laser heterodyne technique.

  13. In situ soft X-ray absorption spectroscopy investigation of electrochemical corrosion of copper in aqueous NaHCO3 solution

    SciTech Connect (OSTI)

    Jiang, Peng; Chen, Jeng-Lung; Borondics, Ferenc; Glans, Per-Anders; West, Mark W.; Chang, Ching-Lin; Salmeron, Miquel; Guo, Jinghua

    2010-03-31

    A novel electrochemical setup has been developed for soft x-ray absorption studies of the electronic structure of electrode materials during electrochemical cycling. In this communication we illustrate the operation of the cell with a study of the corrosion behavior of copper in aqueous NaHCO3 solution via the electrochemically induced changes of its electronic structure. This development opens the way for in situ investigations of electrochemical processes, photovoltaics, batteries, fuel cells, water splitting, corrosion, electrodeposition, and a variety of important biological processes.

  14. High-Speed Multiplexed Spatiotemporally Resolved Measurements of Exhaust Gas Recirculation Dynamics in a Multi-Cylinder Engine Using Laser Absorption Spectroscopy

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

    Yoo, Jihyung; Prikhodko, Vitaly; Parks, James E.; Perfetto, Anthony; Geckler, Sam; Partridge, William P.

    2016-04-01

    The need for more environmentally friendly and efficient energy conversion is of paramount importance in developing and designing next-generation internal combustion (IC) engines for transportation applications. One effective solution to reducing emissions of mono-nitrogen oxides (NOx) is exhaust gas recirculation (EGR), which has been widely implemented in modern vehicles. However, cylinder-to-cylinder and cycle-to-cycle variations in the charge-gas uniformity can be a major barrier to optimum EGR implementation on multi-cylinder engines, and can limit performance, stability, and efficiency. Precise knowledge and fine control over the EGR system is thus crucial, particularly for optimizing advanced engine concepts such as reactivity controlled compressionmore » ignition (RCCI). An absorption-based laser diagnostic was developed to study spatiotemporal charge-gas distributions in an IC engine intake manifold in real-time. The laser was tuned to an absorption band of carbon dioxide (CO2), a standard exhaust-gas marker, near 2.7 µm. The sensor was capable of probing four separate measurement locations simultaneously, and independently analyzing EGR fraction at speeds of 5 kHz (1.2 crank-angle degree (CAD) at 1 k RPM) or faster with high accuracy. Lastly, the probes were used to study spatiotemporal EGR non-uniformities in the intake manifold and ultimately promote the development of more efficient and higher performance engines.« less

  15. Optical absorption and luminescence spectroscopy of U{sup 3+} in K{sub 2}La{ital X}{sub 5} ({ital X}=Cl,Br,I)

    SciTech Connect (OSTI)

    Andres, H.P.; Kraemer, K.; Guedel, H.

    1996-08-01

    The title compounds were synthesized and high-resolution absorption and luminescence spectra measured in the near-infrared, VIS, and near UV regions. The visible absorption spectra are dominated by very intense 5{ital f}{r_arrow}6{ital d} bands overlapping with {ital f}-{ital f} transitions. The onset of the first {ital f}-{ital d} absorption is shifted from 46000 cm{sup {minus}1} in K{sub 2}LaCl{sub 5}:Nd{sup 3+} to 15000 cm{sup {minus}1} in K{sub 2}LaCl{sub 5}:U{sup 3+}. Crystal-field splittings in corresponding {sup 2{ital S}+1}{ital L}{sub {ital J}} multiplets are greater by typically a factor of 2 in the U{sup 3+} doped crystal, thus reflecting the larger extension and stronger interaction of the 5{ital f} electrons with the ligands. {ital f}-{ital f} transitions are typically two orders of magnitude more intense in K{sub 2}LaCl{sub 5}:U{sup 3+} than in K{sub 2}LaCl{sub 5}:Nd{sup 3+}. Along the halide series K{sub 2}La{ital X}{sub 5}:U{sup 3+} ({ital X}=Cl,Br,I) the differences in the position of corresponding {ital f}-{ital d} and {ital f}-{ital f} transitions, crystal-field splittings, vibronic intensities, and excited-state lifetimes can be explained with the increasing covalency, the decreasing phonon energies, the increasing electron-phonon coupling, and the increasing U-{ital X} distances. The {ital f}-{ital d} excited states provide a nonradiative bypass of some {ital f}-{ital f} excited states in the case of all these halide lattices. The excited-state dynamics are determined by a delicate interplay of radiative and nonradiative relaxation processes, they are strongly dependent on the nature of {ital X}. Multiphonon relaxation processes are least competitive in the iodide due to the very low value of 106 cm{sup {minus}1} for the highest-energy phonons. A cross-relaxation mechanism determines the dynamics of the iodide at room temperature. {copyright} {ital 1996 The American Physical Society.}

  16. Effect of Biogeochemical Redox Processes on the Fate and Transport of As and U at an Abandoned Uranium Mine Site: an X-ray Absorption Spectroscopy Study

    SciTech Connect (OSTI)

    Troyer, Lyndsay D.; Stone, James J.; Borch, Thomas

    2014-01-28

    Although As can occur in U ore at concentrations up to 10 wt-%, the fate and transport of both U and As at U mine tailings have not been previously investigated at a watershed scale. The major objective of this study was to determine primary chemical and physical processes contributing to transport of both U and As to a down gradient watershed at an abandoned U mine site in South Dakota. Uranium is primarily transported by erosion at the site, based on decreasing concentrations in sediment with distance from the tailings. equential extractions and U X-ray absorption near-edge fine structure (XANES) fitting indicate that U is immobilised in a near-source sedimentation pond both by prevention of sediment transport and by reduction of UVI to UIV. In contrast to U, subsequent release of As to the watershed takes place from the pond partially due to reductive dissolution of Fe oxy(hydr)oxides. However, As is immobilised by adsorption to clays and Fe oxy(hydr)oxides in oxic zones and by formation of Assulfide mineral phases in anoxic zones down gradient, indicated by sequential extractions and As XANES fitting. This study indicates that As should be considered during restoration of uranium mine sites in order to prevent transport.

  17. NEW ACCURATE MEASUREMENT OF {sup 36}ArH{sup +} AND {sup 38}ArH{sup +} RO-VIBRATIONAL TRANSITIONS BY HIGH RESOLUTION IR ABSORPTION SPECTROSCOPY

    SciTech Connect (OSTI)

    Cueto, M.; Herrero, V. J.; Tanarro, I.; Doménech, J. L.; Cernicharo, J.; Barlow, M. J.; Swinyard, B. M.

    2014-03-01

    The protonated argon ion, {sup 36}ArH{sup +}, was recently identified in the Crab Nebula from Herschel spectra. Given the atmospheric opacity at the frequency of its J = 1-0 and J = 2-1 rotational transitions (617.5 and 1234.6 GHz, respectively), and the current lack of appropriate space observatories after the recent end of the Herschel mission, future studies on this molecule will rely on mid-infrared observations. We report on accurate wavenumber measurements of {sup 36}ArH{sup +} and {sup 38}ArH{sup +} rotation-vibration transitions in the v = 1-0 band in the range 4.1-3.7 μm (2450-2715 cm{sup –1}). The wavenumbers of the R(0) transitions of the v = 1-0 band are 2612.50135 ± 0.00033 and 2610.70177 ± 0.00042 cm{sup –1} (±3σ) for {sup 36}ArH{sup +} and {sup 38}ArH{sup +}, respectively. The calculated opacity for a gas thermalized at a temperature of 100 K and with a linewidth of 1 km s{sup –1} of the R(0) line is 1.6 × 10{sup –15} × N({sup 36}ArH{sup +}). For column densities of {sup 36}ArH{sup +} larger than 1 × 10{sup 13} cm{sup –2}, significant absorption by the R(0) line can be expected against bright mid-IR sources.

  18. On the role of spatial position of bridged oxygen atoms as surface passivants on the ground-state gap and photo-absorption spectrum of silicon nano-crystals

    SciTech Connect (OSTI)

    Nazemi, Sanaz; Soleimani, Ebrahim Asl; Pourfath, Mahdi E-mail: pourfath@iue.tuwien.ac.at

    2015-11-28

    Silicon nano-crystals (NCs) are potential candidates for enhancing and tuning optical properties of silicon for optoelectronic and photo-voltaic applications. Due to the high surface-to-volume ratio, however, optical properties of NC result from the interplay of quantum confinement and surface effects. In this work, we show that both the spatial position of surface terminants and their relative positions have strong effects on NC properties as well. This is accomplished by investigating the ground-state HOMO-LUMO band-gap, the photo-absorption spectra, and the localization and overlap of HOMO and LUMO orbital densities for prototype ∼1.2 nm Si{sub 32–x}H{sub 42–2x}O{sub x} hydrogenated silicon NC with bridged oxygen atoms as surface terminations. It is demonstrated that the surface passivation geometry significantly alters the localization center and thus the overlap of frontier molecular orbitals, which correspondingly modifies the electronic and optical properties of NC.

  19. Structural Analysis of the Mn(IV)/Fe(III) Cofactor of Chlamydia Trachomatis Ribonucleotide Reductase By Extended X-Ray Absorption Fine Structure Spectroscopy And Density Functional Theory Calculations

    SciTech Connect (OSTI)

    Younker, J.M.; Krest, C.M.; Jiang, W.; Krebs, C.; Bollinger, J.M.Jr.; Green, M.T.

    2009-05-28

    The class Ic ribonucleotide reductase from Chlamydia trachomatis (C{bar A}) uses a stable Mn(lV)/ Fe(lll) cofactor to initiate nucleotide reduction by a free-radical mechanism. Extended X-ray absorption fine structure (EXAFS) spectroscopy and density functional theory (DFT) calculations are used to postulate a structure for this cofactor. Fe and Mn K-edge EXAFS data yield an intermetallic distance of -2.92 {angstrom}. The Mn data also suggest the presence of a short 1.74 {angstrom} Mn-O bond. These metrics are compared to the results of DFT calculations on 12 cofactor models derived from the crystal structure of the inactive Fe2(lll/ III) form of the protein. Models are differentiated by the protonation states of their bridging and terminal OH{sub x} ligands as well as the location of the Mn(lV) ion (site 1 or 2). The models that agree best with experimental observation feature a{mu}-1, 3-carboxylate bridge (E120), terminal solvent (H{sub 2}O/OH) to site 1, one {mu}-O bridge, and one {mu}-OH bridge. The site-placement of the metal ions cannot be discerned from the available data.

  20. New developments in micro-X-ray diffraction and X-ray absorption spectroscopy for high-pressure research at 16-BM-D at the Advanced Photon Source

    SciTech Connect (OSTI)

    Park, Changyong Popov, Dmitry; Ikuta, Daijo; Lin, Chuanlong; Kenney-Benson, Curtis; Rod, Eric; Bommannavar, Arunkumar; Shen, Guoyin

    2015-07-15

    The monochromator and focusing mirrors of the 16-BM-D beamline, which is dedicated to high-pressure research with micro-X-ray diffraction (micro-XRD) and X-ray absorption near edge structure (XANES) (6-45 keV) spectroscopy, have been recently upgraded. Monochromatic X-rays are selected by a Si (111) double-crystal monochromator operated in an artificial channel-cut mode and focused to 5 μm × 5 μm (FWHM) by table-top Kirkpatrick-Baez type mirrors located near the sample stage. The typical X-ray flux is ∼5 × 10{sup 8} photons/s at 30 keV. The instrumental resolution, Δq/q{sub max}, reaches to 2 × 10{sup −3} and is tunable through adjustments of the detector distance and X-ray energy. The setup is stable and reproducible, which allows versatile application to various types of experiments including resistive heating and cryogenic cooling as well as ambient temperature compression. Transmission XANES is readily combined with micro-XRD utilizing the fixed-exit feature of the monochromator, which allows combined XRD-XANES measurements at a given sample condition.

  1. Towards higher stability of resonant absorption measurements in pulsed plasmas

    SciTech Connect (OSTI)

    Britun, Nikolay; Michiels, Matthieu; Snyders, Rony

    2015-12-15

    Possible ways to increase the reliability of time-resolved particle density measurements in pulsed gaseous discharges using resonant absorption spectroscopy are proposed. A special synchronization, called “dynamic source triggering,” between a gated detector and two pulsed discharges, one representing the discharge of interest and another being used as a reference source, is developed. An internal digital delay generator in the intensified charge coupled device camera, used at the same time as a detector, is utilized for this purpose. According to the proposed scheme, the light pulses from the reference source follow the gates of detector, passing through the discharge of interest only when necessary. This allows for the utilization of short-pulse plasmas as reference sources, which is critical for time-resolved absorption analysis of strongly emitting pulsed discharges. In addition to dynamic source triggering, the reliability of absorption measurements can be further increased using simultaneous detection of spectra relevant for absorption method, which is also demonstrated in this work. The proposed methods are illustrated by the time-resolved measurements of the metal atom density in a high-power impulse magnetron sputtering (HiPIMS) discharge, using either a hollow cathode lamp or another HiPIMS discharge as a pulsed reference source.

  2. Photoacoustic Microcantilevers for Spectroscopy - Energy Innovation...

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

    Fourier transform infrared spectroscopy to obtain an infrared spectrum of absorption, emission, photoconductivity or Raman scattering of a solid, liquid or gas More ...

  3. Subgap Absorption in Conjugated Polymers

    DOE R&D Accomplishments [OSTI]

    Sinclair, M.; Seager, C. H.; McBranch, D.; Heeger, A. J; Baker, G. L.

    1991-01-01

    Along with X{sup (3)}, the magnitude of the optical absorption in the transparent window below the principal absorption edge is an important parameter which will ultimately determine the utility of conjugated polymers in active integrated optical devices. With an absorptance sensitivity of < 10{sup {minus}5}, Photothermal Deflection Spectroscopy (PDS) is ideal for determining the absorption coefficients of thin films of transparent'' materials. We have used PDS to measure the optical absorption spectra of the conjugated polymers poly(1,4-phenylene-vinylene) (and derivitives) and polydiacetylene-4BCMU in the spectral region from 0.55 eV to 3 eV. Our spectra show that the shape of the absorption edge varies considerably from polymer to polymer, with polydiacetylene-4BCMU having the steepest absorption edge. The minimum absorption coefficients measured varied somewhat with sample age and quality, but were typically in the range 1 cm{sup {minus}1} to 10 cm{sup {minus}1}. In the region below 1 eV, overtones of C-H stretching modes were observed, indicating that further improvements in transparency in this spectral region might be achieved via deuteration of fluorination.

  4. Removal of Ca2+ from the Oxygen-Evolving Complex in Photosystem II Has Minimal Effect on the Mn4O5 Core Structure: A Polarized Mn X-ray Absorption Spectroscopy Study

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

    Lohmiller, Thomas; Shelby, Megan L.; Long, Xi; Yachandra, Vittal K.; Yano, Junko

    2015-05-19

    We studied Ca2+ -depleted and Ca2+ -reconstituted spinach photosystem II using polarized X-ray absorption spectroscopy of oriented PS II preparations to investigate the structural and functional role of the Ca2+ ion in the Mn4O5Ca cluster of the oxygen-evolving complex (OEC). Samples were prepared by low pH/citrate treatment as one-dimensionally ordered membrane layers and poised in the Ca2+ -depleted S1 (S1') and S2 (S2') states, the S2'YZ• state, at which point the catalytic cycle of water oxidation is inhibited, and the Ca2+ -reconstituted S1 state. Polarized Mn K-edge XANES and EXAFS spectra exhibit pronounced dichroism. Polarized EXAFS data of all statesmore » of Ca2+ -depleted PS II investigated show only minor changes in distances and orientations of the Mn-Mn vectors compared to the Ca2+ -containing OEC, which may be attributed to some loss of rigidity of the core structure. Thus, removal of the Ca2+ ion does not lead to fundamental distortion or rearrangement of the tetranuclear Mn cluster, which indicates that the Ca2+ ion in the OEC is not critical for structural maintenance of the cluster, at least in the S1 and S2 states, but fulfills a crucial catalytic function in the mechanism of the water oxidation reaction. On the basis of this structural information, reasons for the inhibitory effect of Ca2+ removal are discussed, attributing to the Ca2+ ion a fundamental role in organizing the surrounding (substrate) water framework and in proton-coupled electron transfer to YZ• (D1-Tyr161).« less

  5. X-ray absorption spectroscopic studies of the active sites of nickel- and copper-containing metalloproteins

    SciTech Connect (OSTI)

    Tan, G.O.

    1993-06-01

    X-ray absorption spectroscopy (XAS) is a useful tool for obtaining structural and chemical information about the active sites of metalloproteins and metalloenzymes. Information may be obtained from both the edge region and the extended X-ray absorption fine structure (EXAFS) or post-edge region of the K-edge X-ray absorption spectrum of a metal center in a compound. The edge contains information about the valence electronic structure of the atom that absorbs the X-rays. It is possible in some systems to infer the redox state of the metal atom in question, as well as the geometry and nature of ligands connected to it, from the features in the edge in a straightforward manner. The EXAFS modulations, being produced by the backscattering of the ejected photoelectron from the atoms surrounding the metal atom, provide, when analyzed, information about the number and type of neighbouring atoms, and the distances at which they occur. In this thesis, analysis of both the edge and EXAFS regions has been used to gain information about the active sites of various metalloproteins. The metalloproteins studied were plastocyanin (Pc), laccase and nickel carbon monoxide dehydrogenase (Ni CODH). Studies of Cu(I)-imidazole compounds, related to the protein hemocyanin, are also reported here.

  6. Atomic vapor laser isotope separation process

    DOE Patents [OSTI]

    Wyeth, R.W.; Paisner, J.A.; Story, T.

    1990-08-21

    A laser spectroscopy system is utilized in an atomic vapor laser isotope separation process. The system determines spectral components of an atomic vapor utilizing a laser heterodyne technique. 23 figs.

  7. X-ray absorption fine structure spectroscopic study of uranium nitrides

    SciTech Connect (OSTI)

    Poineau, Frederic; Yeamans, Charles B.; Cerefice, Gary S.; Sattelberger, Alfred P; Czerwinski, Ken R.

    2012-01-01

    Uranium mononitride (UN), sesquinitride (U2N3) and dinitride (UN2) were characterized by extended X-Ray absorption fine structure spectroscopy. Analysis on UN indicate the presence of three uranium shells at distances of 3.46(3), 4.89(5) and 6.01(6) A and a nitrogen shell at a distance of 2.46(2) A . For U2N3, two absorbing uranium atoms at different crystallographic positions are present in the structure. One of the uranium atoms is surrounded by nitrogen atoms at 2.28(2) A and by uranium atoms at 3.66(4) and 3.95(4) A . The second type of uranium atom is surrounded by nitrogen atoms at 2.33(2) and 2.64(3) A and by uranium atoms at 3.66(4), 3.95(4) and 5.31(5) A . Results on UN2 indicate two uranium shells at 3.71(4) and 5.32(5) A and two nitrogen shells at 2.28(2).

  8. Ultrahigh-resolution spectroscopy with atomic or molecular dark resonances: Exact steady-state line shapes and asymptotic profiles in the adiabatic pulsed regime

    SciTech Connect (OSTI)

    Zanon-Willette, Thomas; Clercq, Emeric de; Arimondo, Ennio [UPMC Univ. Paris 06, UMR 7092, LPMAA, 4 place Jussieu, case 76, F-75005 Paris, France, and CNRS, UMR 7092, LPMAA, 4 place Jussieu, case 76, F-75005 Paris (France); LNE-SYRTE, Observatoire de Paris, CNRS, UPMC, 61 avenue de l'Observatoire, F-75014 Paris (France); Dipartimento di Fisica ''E. Fermi,'' Universita di Pisa, Lgo. B. Pontecorvo 3, I-56122 Pisa (Italy)

    2011-12-15

    Exact and asymptotic line shape expressions are derived from the semiclassical density matrix representation describing a set of closed three-level {Lambda} atomic or molecular states including decoherences, relaxation rates, and light shifts. An accurate analysis of the exact steady-state dark-resonance profile describing the Autler-Townes doublet, the electromagnetically induced transparency or coherent population trapping resonance, and the Fano-Feshbach line shape leads to the linewidth expression of the two-photon Raman transition and frequency shifts associated to the clock transition. From an adiabatic analysis of the dynamical optical Bloch equations in the weak field limit, a pumping time required to efficiently trap a large number of atoms into a coherent superposition of long-lived states is established. For a highly asymmetrical configuration with different decay channels, a strong two-photon resonance based on a lower states population inversion is established when the driving continuous-wave laser fields are greatly unbalanced. When time separated resonant two-photon pulses are applied in the adiabatic pulsed regime for atomic or molecular clock engineering, where the first pulse is long enough to reach a coherent steady-state preparation and the second pulse is very short to avoid repumping into a new dark state, dark-resonance fringes mixing continuous-wave line shape properties and coherent Ramsey oscillations are created. Those fringes allow interrogation schemes bypassing the power broadening effect. Frequency shifts affecting the central clock fringe computed from asymptotic profiles and related to the Raman decoherence process exhibit nonlinear shapes with the three-level observable used for quantum measurement. We point out that different observables experience different shifts on the lower-state clock transition.

  9. ABSORPTION ANALYZER

    DOE Patents [OSTI]

    Brooksbank, W.A. Jr.; Leddicotte, G.W.; Strain, J.E.; Hendon, H.H. Jr.

    1961-11-14

    A means was developed for continuously computing and indicating the isotopic assay of a process solution and for automatically controlling the process output of isotope separation equipment to provide a continuous output of the desired isotopic ratio. A counter tube is surrounded with a sample to be analyzed so that the tube is exactly in the center of the sample. A source of fast neutrons is provided and is spaced from the sample. The neutrons from the source are thermalized by causing them to pass through a neutron moderator, and the neutrons are allowed to diffuse radially through the sample to actuate the counter. A reference counter in a known sample of pure solvent is also actuated by the thermal neutrons from the neutron source. The number of neutrons which actuate the detectors is a function of a concentration of the elements in solution and their neutron absorption cross sections. The pulses produced by the detectors responsive to each neu tron passing therethrough are amplified and counted. The respective times required to accumulate a selected number of counts are measured by associated timing devices. The concentration of a particular element in solution may be determined by utilizing the following relation: T2/Ti = BCR, where B is a constant proportional to the absorption cross sections, T2 is the time of count collection for the unknown solution, Ti is the time of count collection for the pure solvent, R is the isotopic ratlo, and C is the molar concentration of the element to be determined. Knowing the slope constant B for any element and when the chemical concentration is known, the isotopic concentration may be readily determined, and conversely when the isotopic ratio is known, the chemical concentrations may be determined. (AEC)

  10. Method for quantitative determination and separation of trace amounts of chemical elements in the presence of large quantities of other elements having the same atomic mass

    DOE Patents [OSTI]

    Miller, C.M.; Nogar, N.S.

    1982-09-02

    Photoionization via autoionizing atomic levels combined with conventional mass spectroscopy provides a technique for quantitative analysis of trace quantities of chemical elements in the presence of much larger amounts of other elements with substantially the same atomic mass. Ytterbium samples smaller than 10 ng have been detected using an ArF* excimer laser which provides the atomic ions for a time-of-flight mass spectrometer. Elemental selectivity of greater than 5:1 with respect to lutetium impurity has been obtained. Autoionization via a single photon process permits greater photon utilization efficiency because of its greater absorption cross section than bound-free transitions, while maintaining sufficient spectroscopic structure to allow significant photoionization selectivity between different atomic species. Separation of atomic species from others of substantially the same atomic mass is also described.

  11. Oxygen-Atom Defects In 6H Silicon Carbide Implanted Using 24- MeV O{sup 3+} Ions Measured Using Three-Dimensional Positron Annihilation Spectroscopy System (3DPASS)

    SciTech Connect (OSTI)

    Williams, Christopher S.; Petrosky, James C.; Burggraf, Larry W.

    2011-06-01

    Three dimensional electron-positron (e{sup -}-e{sup +}) momentum distributions were measured for single crystal 6H silicon carbide (SiC); both virgin and having implanted oxygen-atom defects. 6H SiC samples were irradiated by 24- MeV O{sup 3+} ions at 20 particle-nanoamps at the Sandia National Laboratory's Ion Beam Facility. O{sup 3+} ions were implanted 10.8 {mu}m deep normal to the (0001) face of one side of the SiC samples. During positron annihilation measurements, the opposite face of the 254.0-{mu}m thick SiC samples was exposed to positrons from a {sup 22}Na source. This technique reduced the influence on the momentum measurements of vacancy-type defects resulting from knock-on damage by the O{sup 3+} ions. A three-dimensional positron annihilation spectroscopy system (3DPASS) was used to measure e{sup -}-e{sup +} momentum distributions for virgin and irradiated 6H SiC crystal both before and following annealing. 3DPASS simultaneously measures coincident Doppler-broadening (DBAR) and angular correlation of annihilation radiation (ACAR) spectra. DBAR ratio plots and 2D ACAR spectra are presented. Changes in the momentum anisotropies relative to crystal orientation observed in 2D ACAR spectra for annealed O-implanted SiC agree with the local structure of defect distortion predicted using Surface Integrated Molecular Orbital/Molecular Mechanics (SIMOMM). Oxygen atoms insert between Si and C atoms increasing their separation by 0.9 A forming a Si-O-C bond angle of {approx}150 deg.

  12. Molecular conformation changes in alkylthiol ligands as a function of size in gold nanoparticles: X-ray absorption studies

    SciTech Connect (OSTI)

    Ramallo-Lopez, J. M.; Giovanetti, L. J.; Requejo, F. G.; Isaacs, S. R.; Shon, Y. S.; Salmeron, M.

    2006-08-15

    The bonding of hexanethiols to gold nanoparticles of 1.5, 2.0, and 3 nm was studied using x-ray absorption near-edge spectroscopy (XANES) and extended x-ray absorption fine structure (EXAFS). The XANES spectra revealed that a substantial fraction of weakly bound hexanethiol molecules are present in addition to those forming covalent bonds with Au atoms. The weakly bound molecules can be removed by washing in dichloromethane. After removal of the weakly bound molecules the S K-edge XANES reveals peaks due to S-Au and S-C bonds with intensities that change as a function of particle size. Au L{sub 3}-edge EXAFS results indicate that these changes follow the changes in coordination number of Au to the S atoms at the surface of the particles.

  13. Atomic layer deposition of zinc sulfide with Zn(TMHD){sub 2}

    SciTech Connect (OSTI)

    Short, Andrew; Jewell, Leila; Doshay, Sage; Church, Carena; Keiber, Trevor; Bridges, Frank; Carter, Sue; Alers, Glenn

    2013-01-15

    The atomic layer deposition (ALD) of ZnS films with Zn(TMHD){sub 2} and in situ generated H{sub 2}S as precursors was investigated, over a temperature range of 150-375 Degree-Sign C. ALD behavior was confirmed by investigation of growth behavior and saturation curves. The properties of the films were studied with atomic force microscopy, scanning electron microscopy, energy-dispersive x-ray spectroscopy, ultraviolet-visible-infrared spectroscopy, and extended x-ray absorption fine structure. The results demonstrate a film that can penetrate a porous matrix, with a local Zn structure of bulk ZnS, and a band gap between 3.5 and 3.6 eV. The ZnS film was used as a buffer layer in nanostructured PbS quantum dot solar cell devices.

  14. Attosecond Electron Wave-Packet Interference Observed by Transient Absorption

    SciTech Connect (OSTI)

    Holler, M.; Schapper, F.; Gallmann, L.; Keller, U.

    2011-03-25

    We perform attosecond time-resolved transient absorption spectroscopy around the first ionization threshold of helium and observe rapid oscillations of the absorption of the individual harmonics as a function of time delay with respect to a superimposed, moderately strong infrared laser field. The phase relation between the absorption modulation of individual harmonics gives direct evidence for the interference of transiently bound electronic wave packets as the mechanism behind the absorption modulation.

  15. ATHENA, ARTEMIS, HEPHAESTUS: data analysis for X-ray absorption spectropscopy using IFEFFIT

    SciTech Connect (OSTI)

    Ravel, B.; Newville, M.

    2010-07-20

    A software package for the analysis of X-ray absorption spectroscopy (XAS) data is presented. This package is based on the IFEFFIT library of numerical and XAS algorithms and is written in the Perl programming language using the Perl/Tk graphics toolkit. The programs described here are: (i) ATHENA, a program for XAS data processing, (ii) ARTEMIS, a program for EXAFS data analysis using theoretical standards from FEFF and (iii) HEPHAESTUS, a collection of beamline utilities based on tables of atomic absorption data. These programs enable high-quality data analysis that is accessible to novices while still powerful enough to meet the demands of an expert practitioner. The programs run on all major computer platforms and are freely available under the terms of a free software license.

  16. Novel insight into the hydrogen absorption mechanism at the Pd(110) surface

    SciTech Connect (OSTI)

    Ohno, Satoshi E-mail: wilde@iis.u-tokyo.ac.jp; Wilde, Markus E-mail: wilde@iis.u-tokyo.ac.jp; Fukutani, Katsuyuki

    2014-04-07

    The microscopic mechanism of low-temperature (80 K < T < 160 K) hydrogen (H) ingress into the H{sub 2} (<2.66 10{sup ?3} Pa) exposed Pd(110) surface is explored by H depth profiling with {sup 15}N nuclear reaction analysis (NRA) and thermal desorption spectroscopy (TDS) with isotope (H, D) labeled surface hydrogen. NRA and TDS reveal two types of absorbed hydrogen states of distinctly different depth distributions. Between 80 K and ?145 K a near-surface hydride phase evolving as the TDS ?{sub 1} feature at 160 K forms, which initially extends only several nanometers into depth. On the other hand, a bulk-absorbed hydrogen state develops between 80 K and ?160 K which gives rise to a characteristic ?{sub 3} TDS feature above 190 K. These two absorbed states are populated at spatially separated surface entrance channels. The near-surface hydride is populated through rapid penetration at minority sites (presumably defects) while the bulk-absorbed state forms at regular terraces with much lower probability per site. In both cases, absorption of gas phase hydrogen transfers pre-adsorbed hydrogen atoms below the surface and replaces them at the chemisorption sites by post-dosed hydrogen in a process that requires much less activation energy (<100 meV) than monatomic diffusion of chemisorbed H atoms into subsurface sites. This small energy barrier suggests that the rate-determining step of the absorption process is either H{sub 2} dissociation on the H-saturated Pd surface or a concerted penetration mechanism, where excess H atoms weakly bound to energetically less favorable adsorption sites stabilize themselves in the chemisorption wells while pre-chemisorbed H atoms simultaneously transit into the subsurface. The peculiarity of absorption at regular Pd(110) terraces in comparison to Pd(111) and Pd(100) is discussed.

  17. Atomic force microscopy and x-ray photoelectron spectroscopy investigations of the morphology and chemistry of a PdCl{sub 2}/SnCl{sub 2} electroless plating catalysis system adsorbed onto shape memory alloy particles

    SciTech Connect (OSTI)

    Silvain, J.F.; Fouassier, O.; Lescaux, S.

    2004-11-01

    A study of the different stages of the electroless deposition of copper on micronic NiTi shape memory alloy particles activated by one-step and two-step methods has been conducted from both a chemical and a morphological point of view. The combination of x-ray photoelectron spectroscopy (XPS) measurements and atomic force microscopy (AFM) imaging has allowed detection of the distribution of the formed compounds and depth quantification and estimation of the surface topographic parameters. For the two-step method, at the sensitization of the early stages, it is observed by AFM that Sn is absorbed in form of clusters that tend to completely cover the surface and form a continuous film. XPS analysis have shown that Sn and Pd are first absorbed in form of oxide (SnO{sub 2} and PdO) and hydroxide [Sn(OH){sub 4}]. After the entire sensitization step, the NiTi substrate is covered with Sn-based compounds. After the sensitization and the activation steps the powder roughness increases. Behavior of the Sn and Pd growth for the one-step method does not follow the behavior found for the two-step method. Indeed, XPS analysis shows a three-dimensional (3D) growth of Pd clusters on top of a mixture of metallic tin, oxide (SnO) and hydroxide [Sn(OH){sub 2}]. These Pd clusters are covered with a thin layer of Pd-oxide contamination induced by the electroless process. The mean roughness for the one-step and two-step processes are equivalent. After copper deposition, the decrease of mean roughness is attributed to a filling of surface valleys, observed after the Sn-Pd coating step.

  18. Soft X-ray Spectroscopy Study of the Electronic Structure of Oxidized and Partially Oxidized Magnetite Nanoparticles

    SciTech Connect (OSTI)

    Gilbert, Benjamin; Katz, Jordan E.; Denlinger, Jonathan D.; Yin, Yadong; Falcone, Roger; Waychunas, Glenn A.

    2010-10-24

    The crystal structure of magnetite nanoparticles may be transformed to maghemite by complete oxidation, but under many relevant conditions the oxidation is partial, creating a mixed-valence material with structural and electronic properties that are poorly characterized. We used X-ray diffraction, Fe K-edge extended X-ray absorption fine structure (EXAFS) spectroscopy, and soft X-ray absorption and emission spectroscopy to characterize the products of oxidizing uncoated and oleic acid-coated magnetite nanoparticles in air. The oxidization of uncoated magnetite nanoparticles creates a material that is structurally and electronically indistinguishable from maghemite. By contrast, while oxidized oleic acid-coated nanoparticles are also structurally indistinguishable from maghemite, Fe L-edge spectroscopy revealed the presence of interior reduced iron sites even after a 2-year period. We used X-ray emission spectroscopy at the O K-edge to study the valence bands (VB) of the iron oxide nanoparticles, using resonant excitation to remove the contributions from oxygen atoms in the ligands and from low-energy excitations that obscured the VB edge. The bonding in all nanoparticles was typical of maghemite, with no detectable VB states introduced by the long-lived, reduced-iron sites in the oleic acid-coated sample. However, O K-edge absorption spectroscopy observed a 0.2 eV shift in the position of the lowest unoccupied states in the coated sample, indicating an increase in the semiconductor band gap relative to bulk stoichiometric maghemite that was also observed by optical absorption spectroscopy. The results show that the ferrous iron sites within ferric iron oxide nanoparticles coated by an organic ligand can persist under ambient conditions with no evidence of a distinct interior phase and can exert an effect on the global electronic and optical properties of the material. This phenomenon resembles the band gap enlargement caused by electron accumulation in the

  19. VARIABLE SODIUM ABSORPTION IN A LOW-EXTINCTION TYPE Ia SUPERNOVA...

    Office of Scientific and Technical Information (OSTI)

    We present the third detection of such variable absorption, based on six epochs of ... Country of Publication: United States Language: English Subject: 74 ATOMIC AND MOLECULAR ...

  20. Ultrasonic-Based Mode-Synthesizing Atomic Force Microscopy -...

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

    Only ultrasonic-based atomic force microscopy in the industry Sufficiently flexible for compatibility with spectroscopic approaches such as Raman spectroscopy Easily adaptable to ...

  1. ATOM | NISAC

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

    NISACATOM content top Network Optimization Models (RNAS and ATOM) Posted by Admin on Mar 1, 2012 in | Comments 0 comments Many critical infrastructures can be represented by a...

  2. Absorption Cooling Basics

    Office of Energy Efficiency and Renewable Energy (EERE)

    Absorption coolers use heat rather than electricity as their energy source. Because natural gas is the most common heat source for absorption cooling, it is also referred to as gas-fired cooling.

  3. Atomic hydrogen in planetary nebulae

    SciTech Connect (OSTI)

    Schneider, S.E.; Silverglate, P.R.; Altschuler, D.R.; Giovanardi, C.

    1987-03-01

    The authors searched for neutral atomic hydrogen associated with 22 planetary nebulae and three evolved stars in the 21 cm line at the Arecibo Observatory. Objects whose radial velocities permitted discrimination from Galactic H I were chosen for observation. Hydrogen was detected in absorption from IC 4997. From the measurements new low limits are derived to the mass of atomic hydrogen associated with the undetected nebulae. Radio continuum observations were also made of several of the nebulae at 12.6 cm. The authors reexamine previous measurements of H I in planetary nebulae, and present the data on a consistent footing. The question of planetary nebula distances is considered at length. Finally, implications of the H I measurements for nebular evolution are discussed and it is suggested that atomic hydrogen seen in absorption was expelled from the progenitor star during the final 1000 yr prior to the onset of ionization. 68 references.

  4. Towards ALD thin film stabilized single-atom Pd 1 catalysts

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

    Piernavieja-Hermida, Mar; Lu, Zheng; White, Anderson; Low, Ke-Bin; Wu, Tianpin; Elam, Jeffrey W.; Wu, Zili; Lei, Yu

    2016-07-27

    Supported precious metal single-atom catalysts have shown interesting activity and selectivity in recent studies. However, agglomeration of these highly mobile mononuclear surface species can eliminate their unique catalytic properties. In this paper, we study a strategy for synthesizing thin film stabilized single-atom Pd1 catalysts using atomic layer deposition (ALD). The thermal stability of the Pd1 catalysts is significantly enhanced by creating a nanocavity thin film structure. In situ infrared spectroscopy and Pd K-edge X-ray absorption spectroscopy (XAS) revealed that the Pd1 was anchored on the surface through chlorine sites. The thin film stabilized Pd1 catalysts were thermally stable under bothmore » oxidation and reduction conditions. The catalytic performance in the methanol decomposition reaction is found to depend on the thickness of protecting layers. While Pd1 catalysts showed promising activity at low temperature in a methanol decomposition reaction, 14 cycle TiO2 protected Pd1 was less active at high temperature. Pd L3 edge XAS indicated that the low reactivity compared with Pd nanoparticles is due to the strong adsorption of carbon monoxide even at 250 °C. Lastly, these results clearly show that the ALD nanocavities provide a basis for future design of single-atom catalysts that are highly efficient and stable.« less

  5. The electronic characterization of biphenylene—Experimental and theoretical insights from core and valence level spectroscopy

    SciTech Connect (OSTI)

    Lüder, Johann; Sanyal, Biplab; Eriksson, Olle; Brena, Barbara; Puglia, Carla; Simone, Monica de; Totani, Roberta; Coreno, Marcello; Grazioli, Cesare

    2015-02-21

    In this paper, we provide detailed insights into the electronic structure of the gas phase biphenylene molecule through core and valence spectroscopy. By comparing results of X-ray Photoelectron Spectroscopy (XPS) measurements with ΔSCF core-hole calculations in the framework of Density Functional Theory (DFT), we could decompose the characteristic contributions to the total spectra and assign them to non-equivalent carbon atoms. As a difference with similar molecules like biphenyl and naphthalene, an influence of the localized orbitals on the relative XPS shifts was found. The valence spectrum probed by photoelectron spectroscopy at a photon energy of 50 eV in conjunction with hybrid DFT calculations revealed the effects of the localization on the electronic states. Using the transition potential approach to simulate the X-ray absorption spectroscopy measurements, similar contributions from the non-equivalent carbon atoms were determined from the total spectrum, for which the slightly shifted individual components can explain the observed asymmetric features.

  6. Soft-x-ray spectroscopy study of nanoscale materials

    SciTech Connect (OSTI)

    Guo, J.-H.

    2005-07-30

    The ability to control the particle size and morphology of nanoparticles is of crucial importance nowadays both from a fundamental and industrial point of view considering the tremendous amount of high-tech applications. Controlling the crystallographic structure and the arrangement of atoms along the surface of nanostructured material will determine most of its physical properties. In general, electronic structure ultimately determines the properties of matter. Soft X-ray spectroscopy has some basic features that are important to consider. X-ray is originating from an electronic transition between a localized core state and a valence state. As a core state is involved, elemental selectivity is obtained because the core levels of different elements are well separated in energy, meaning that the involvement of the inner level makes this probe localized to one specific atomic site around which the electronic structure is reflected as a partial density-of-states contribution. The participation of valence electrons gives the method chemical state sensitivity and further, the dipole nature of the transitions gives particular symmetry information. The new generation synchrotron radiation sources producing intensive tunable monochromatized soft X-ray beams have opened up new possibilities for soft X-ray spectroscopy. The introduction of selectively excited soft X-ray emission has opened a new field of study by disclosing many new possibilities of soft X-ray resonant inelastic scattering. In this paper, some recent findings regarding soft X-ray absorption and emission studies of various nanostructured systems are presented.

  7. High resolution x-ray fluorescence spectroscopy - a new technique for site- and spin-selectivity

    SciTech Connect (OSTI)

    Wang, Xin

    1996-12-01

    X-ray spectroscopy has long been used to elucidate electronic and structural information of molecules. One of the weaknesses of x-ray absorption is its sensitivity to all of the atoms of a particular element in a sample. Through out this thesis, a new technique for enhancing the site- and spin-selectivity of the x-ray absorption has been developed. By high resolution fluorescence detection, the chemical sensitivity of K emission spectra can be used to identify oxidation and spin states; it can also be used to facilitate site-selective X-ray Absorption Near Edge Structure (XANES) and site-selective Extended X-ray Absorption Fine Structure (EXAFS). The spin polarization in K fluorescence could be used to generate spin selective XANES or spin-polarized EXAFS, which provides a new measure of the spin density, or the nature of magnetic neighboring atoms. Finally, dramatic line-sharpening effects by the combination of absorption and emission processes allow observation of structure that is normally unobservable. All these unique characters can enormously simplify a complex x-ray spectrum. Applications of this novel technique have generated information from various transition-metal model compounds to metalloproteins. The absorption and emission spectra by high resolution fluorescence detection are interdependent. The ligand field multiplet model has been used for the analysis of K{alpha} and K{beta} emission spectra. First demonstration on different chemical states of Fe compounds has shown the applicability of site selectivity and spin polarization. Different interatomic distances of the same element in different chemical forms have been detected using site-selective EXAFS.

  8. A table-top femtosecond time-resolved soft x-ray transient absorption spectrometer

    SciTech Connect (OSTI)

    Leone, Stephen; Loh, Zhi-Heng; Khalil, Munira; Correa, Raoul E.; Leone, Stephen R.

    2008-05-21

    A laser-based, table-top instrument is constructed to perform femtosecond soft x-ray transient absorption spectroscopy. Ultrashort soft x-ray pulses produced via high-order harmonic generation of the amplified output of a femtosecond Ti:sapphire laser system are used to probe atomic core-level transient absorptions in atoms and molecules. The results provide chemically specific, time-resolved dynamics with sub-50-fs time resolution. In this setup, high-order harmonics generated in a Ne-filled capillary waveguide are refocused by a gold-coated toroidal mirror into the sample gas cell, where the soft x-ray light intersects with an optical pump pulse. The transmitted high-order harmonics are spectrally dispersed with a home-built soft x-ray spectrometer, which consists of a gold-coated toroidal mirror, a uniform-line spaced plane grating, and a soft x-ray CCD camera. The optical layout of the instrument, design of the soft x-ray spectrometer, and spatial and temporal characterization of the high-order harmonics are described. Examples of static and time-resolved photoabsorption spectra collected on this apparatus are presented.

  9. Collision--induced absorption in dense atmospheres of cool stars

    SciTech Connect (OSTI)

    Borysow, Aleksandra; Joergensen, Uffe Graae

    1999-04-01

    In the atmosphere of the Sun the major interaction between the matter and the radiation is through light absorption by ions (predominantly the negative ion of hydrogen atoms), neutral atoms and a small amount of polar molecules. The majority of stars in the universe are, however, cooler and denser than our Sun, and for a large fraction of these, the above absorption processes are very weak. Here, collision-induced absorption (CIA) becomes the dominant opacity source. The radiation is absorbed during very short mutual passages ('collisions') of two non-polar molecules (and/or atoms), while their electric charge distributions are temporarily distorted which gives rise to a transient dipole moment. We present here a review of the present-day knowledge about the impact of collision-induced absorption processes on the structure and the spectrum of such stars.

  10. Laser spectroscopy of the 4s4p {sup 3}P{sub 2} - 4s3d {sup 1}D{sub 2} transition on magnetically trapped calcium atoms

    SciTech Connect (OSTI)

    Dammalapati, U.; Norris, I.; Burrows, C.; Riis, E.

    2011-06-15

    Laser excitation of the 4s4p {sup 3}P{sub 2} - 4s3d {sup 1}D{sub 2} transition in atomic calcium has been observed and the wavelength determined to 1530.5298(6) nm. The metastable 4s4p {sup 3}P{sub 2} atoms were magnetically trapped in the quadrupole magnetic field of a magneto-optical trap. This state represents the only ''loss'' channel for the calcium atoms when laser cooled on the 4s{sup 2} {sup 1}S{sub 0} - 4s4p {sup 1}P{sub 1} transition. A rate equation model shows that an order of magnitude more atoms are trapped in this state compared with those taking part in the main cooling cycle. Excitation of the {sup 3}P{sub 2} atoms back up to the 4s3d {sup 1}D{sub 2} state provides a means of accessing these atoms. Efficient repumping is achieved if the 1530-nm laser is used in conjunction with a 672-nm laser driving the 4s3d {sup 1}D{sub 2} - 4s5p {sup 1}P{sub 1} transition. In the present experiment, we detected about 4.5x10{sup 4} trapped {sup 3}P{sub 2} atoms, a relatively low atom density, and measured a lifetime of approximately 1 s, which is limited by background collisions.

  11. The Atomic AXAFS and XANES Techniques as Applied to Heterogeneous Catalysis and Electrocatalysis

    SciTech Connect (OSTI)

    Ramaker, D.; Koningsberger, D

    2010-01-01

    X-Ray absorption spectroscopy (XAFS) is an attractive in situ and in operando technique. In recent years, the more conventional extended X-ray absorption fine structure (EXAFS) data analysis technique has been complemented by two newer analysis methods: the 'atomic' XAFS (AXAFS) technique, which analyzes the scattering from the absorber atom itself, and the {Delta}{mu} XANES technique, which uses a difference method to isolate the changes in the X-ray absorption near edge structure (XANES) due to adsorbates on a metal surface. With AXAFS it is possible to follow the electronic effect a support has on a metal particle; with {Delta}{mu} XANES it is possible to determine the adsorbate, the specific adsorption sites and adsorbate coverage on a metal catalyst. This unprecedented new information helps a great deal to unravel the complex kinetic mechanisms operating in working reactors or fuelcell systems. The fundamental principles and methodology for applying the AXAFS and {Delta}{mu} XANES techniques are given here, and then specific applications are summarized, including H adsorption on supported Pt in the gas phase, wateractivation at a Pt cathode and methanol oxidation at a Pt anode in an electrochemical cell, sulfur oxidation on Pt, and oxygenreduction on a Au/SnO{sub x} cathode. Finally, the future outlook for time and/or space resolved applications of these techniques is contemplated.

  12. Residential Absorption Water Heater

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

    Residential Absorption Water Heater 2014 Building Technologies Office Peer Review Kyle ... Target MarketAudience: Residential gas water heating Key Partners: GE CRADA partner SRA ...

  13. On-Board Measurement of Ammonia and Nitrous Oxide Using Feedback Absorption

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

    Laser Spectroscopy Combined with Amplified Resonance and Low Pressure Sampling | Department of Energy Board Measurement of Ammonia and Nitrous Oxide Using Feedback Absorption Laser Spectroscopy Combined with Amplified Resonance and Low Pressure Sampling On-Board Measurement of Ammonia and Nitrous Oxide Using Feedback Absorption Laser Spectroscopy Combined with Amplified Resonance and Low Pressure Sampling A first set of results has found that LASAR and VLPS data in the laboratory closely

  14. Atom Interferometry

    ScienceCinema (OSTI)

    Mark Kasevich

    2010-01-08

    Atom de Broglie wave interferometry has emerged as a tool capable of addressing a diverse set of questions in gravitational and condensed matter physics, and as an enabling technology for advanced sensors in geodesy and navigation. This talk will review basic principles, then discuss recent applications and future directions. Scientific applications to be discussed include measurement of G (Newton?s constant), tests of the Equivalence Principle and post-Newtonian gravity, and study of the Kosterlitz-Thouless phase transition in layered superfluids. Technology applications include development of precision gryoscopes and gravity gradiometers. The talk will conclude with speculative remarks looking to the future: Can atom interference methods be sued to detect gravity waves? Can non-classical (entangled/squeezed state) atom sources lead to meaningful sensor performance improvements?

  15. Atom Interferometry

    SciTech Connect (OSTI)

    Mark Kasevich

    2008-05-07

    Atom de Broglie wave interferometry has emerged as a tool capable of addressing a diverse set of questions in gravitational and condensed matter physics, and as an enabling technology for advanced sensors in geodesy and navigation. This talk will review basic principles, then discuss recent applications and future directions. Scientific applications to be discussed include measurement of G (Newton’s constant), tests of the Equivalence Principle and post-Newtonian gravity, and study of the Kosterlitz-Thouless phase transition in layered superfluids. Technology applications include development of precision gryoscopes and gravity gradiometers. The talk will conclude with speculative remarks looking to the future: Can atom interference methods be sued to detect gravity waves? Can non-classical (entangled/squeezed state) atom sources lead to meaningful sensor performance improvements?

  16. Order within disorder: The atomic structure of ion-beam sputtered...

    Office of Scientific and Technical Information (OSTI)

    ... Sponsoring Org: USDOE Country of Publication: United States Language: English Subject: 36 MATERIALS SCIENCE extended x-ray absorption fine structure spectroscopy; tantalum; crystal ...

  17. Temperature dependent evolution of the electronic and local atomic structure in the cubic colossal magnetoresistive manganite La1-xSrxMnO3

    SciTech Connect (OSTI)

    Arenholz, Elke; Mannella, N.; Booth, C.H.; Rosenhahn, A.; Sell, B.C.; Nambu, A.; Marchesini, S.; Mun, B. S.; Yang, S.-H.; Watanabe, M.; Ibrahim, K.; Arenholz, E.; Young, A.; Guo, J.; Tomioka, Y.; Fadley, C.S.

    2007-12-06

    We have studied the temperature-dependent evolution of the electronic and local atomic structure in the cubic colossal magnetoresistive manganite La{sub 1-x}Sr{sub x}MnO{sub 3} (x= 0.3-0.4) with core and valence level photoemission (PE), x-ray absorption spectroscopy (XAS), x-ray emission spectroscopy (XES), resonant inelastic x-ray scattering (RIXS), extended x-ray absorption fine structure (EXAFS) spectroscopy and magnetometry. As the temperature is varied across the Curie temperature T{sub c}, our PE experiments reveal a dramatic change of the electronic structure involving an increase in the Mn spin moment from {approx} 3 {micro}B to {approx} 4 {micro}B, and a modification of the local chemical environment of the other constituent atoms indicative of electron localization on the Mn atom. These effects are reversible and exhibit a slow-timescale {approx}200 K-wide hysteresis centered at T{sub c}. Based upon the probing depths accessed in our PE measurements, these effects seem to survive for at least 35-50 {angstrom} inward from the surface, while other consistent signatures for this modification of the electronic structure are revealed by more bulk sensitive spectroscopies like XAS and XES/RIXS. We interpret these effects as spectroscopic fingerprints for polaron formation, consistent with the presence of local Jahn-Teller distortions of the MnO{sub 6} octahedra around the Mn atom, as revealed by the EXAFS data. Magnetic susceptibility measurements in addition show typical signatures of ferro-magnetic clusters formation well above the Curie temperature.

  18. Solar absorption surface panel

    DOE Patents [OSTI]

    Santala, Teuvo J.

    1978-01-01

    A composite metal of aluminum and nickel is used to form an economical solar absorption surface for a collector plate wherein an intermetallic compound of the aluminum and nickel provides a surface morphology with high absorptance and relatively low infrared emittance along with good durability.

  19. Determination of Atomic Data Pertinent to the Fusion Energy Program

    SciTech Connect (OSTI)

    Reader, J.

    2013-06-11

    We summarize progress that has been made on the determination of atomic data pertinent to the fusion energy program. Work is reported on the identification of spectral lines of impurity ions, spectroscopic data assessment and compilations, expansion and upgrade of the NIST atomic databases, collision and spectroscopy experiments with highly charged ions on EBIT, and atomic structure calculations and modeling of plasma spectra.

  20. Absorption heat pump system

    DOE Patents [OSTI]

    Grossman, G.

    1982-06-16

    The efficiency of an absorption heat pump system is improved by conducting liquid from a second stage evaporator thereof to an auxiliary heat exchanger positioned downstream of a primary heat exchanger in the desorber of the system.

  1. Absorption heat pump system

    DOE Patents [OSTI]

    Grossman, Gershon

    1984-01-01

    The efficiency of an absorption heat pump system is improved by conducting liquid from a second stage evaporator thereof to an auxiliary heat exchanger positioned downstream of a primary heat exchanger in the desorber of the system.

  2. Optical absorption measurement system

    DOE Patents [OSTI]

    Draggoo, Vaughn G.; Morton, Richard G.; Sawicki, Richard H.; Bissinger, Horst D.

    1989-01-01

    The system of the present invention contemplates a non-intrusive method for measuring the temperature rise of optical elements under high laser power optical loading to determine the absorption coefficient. The method comprises irradiating the optical element with a high average power laser beam, viewing the optical element with an infrared camera to determine the temperature across the optical element and calculating the absorption of the optical element from the temperature.

  3. Solar selective absorption coatings

    DOE Patents [OSTI]

    Mahoney, Alan R.; Reed, Scott T.; Ashley, Carol S.; Martinez, F. Edward

    2004-08-31

    A new class of solar selective absorption coatings are disclosed. These coatings comprise a structured metallic overlayer such that the overlayer has a sub-micron structure designed to efficiently absorb solar radiation, while retaining low thermal emissivity for infrared thermal radiation. A sol-gel layer protects the structured metallic overlayer from mechanical, thermal, and environmental degradation. Processes for producing such solar selective absorption coatings are also disclosed.

  4. Solar selective absorption coatings

    DOE Patents [OSTI]

    Mahoney, Alan R.; Reed, Scott T.; Ashley, Carol S.; Martinez, F. Edward

    2003-10-14

    A new class of solar selective absorption coatings are disclosed. These coatings comprise a structured metallic overlayer such that the overlayer has a sub-micron structure designed to efficiently absorb solar radiation, while retaining low thermal emissivity for infrared thermal radiation. A sol-gel layer protects the structured metallic overlayer from mechanical, thermal, and environmental degradation. Processes for producing such solar selective absorption coatings are also disclosed.

  5. Seven-effect absorption refrigeration

    DOE Patents [OSTI]

    DeVault, R.C.; Biermann, W.J.

    1989-05-09

    A seven-effect absorption refrigeration cycle is disclosed utilizing three absorption circuits. In addition, a heat exchanger is used for heating the generator of the low absorption circuit with heat rejected from the condenser and absorber of the medium absorption circuit. A heat exchanger is also provided for heating the generator of the medium absorption circuit with heat rejected from the condenser and absorber of the high absorption circuit. If desired, another heat exchanger can also be provided for heating the evaporator of the high absorption circuit with rejected heat from either the condenser or absorber of the low absorption circuit. 1 fig.

  6. Seven-effect absorption refrigeration

    DOE Patents [OSTI]

    DeVault, Robert C.; Biermann, Wendell J.

    1989-01-01

    A seven-effect absorption refrigeration cycle is disclosed utilizing three absorption circuits. In addition, a heat exchanger is used for heating the generator of the low absorption circuit with heat rejected from the condenser and absorber of the medium absorption circuit. A heat exchanger is also provided for heating the generator of the medium absorption circuit with heat rejected from the condenser and absorber of the high absorption circuit. If desired, another heat exchanger can also be provided for heating the evaporator of the high absorption circuit with rejected heat from either the condenser or absorber of the low absorption circuit.

  7. Temperature measurement of cold atoms using single-atom transits and Monte Carlo simulation in a strongly coupled atom-cavity system

    SciTech Connect (OSTI)

    Li, Wenfang; Du, Jinjin; Wen, Ruijuan; Yang, Pengfei; Li, Gang; Zhang, Tiancai; Liang, Junjun

    2014-03-17

    We investigate the transmission of single-atom transits based on a strongly coupled cavity quantum electrodynamics system. By superposing the transit transmissions of a considerable number of atoms, we obtain the absorption spectra of the cavity induced by single atoms and obtain the temperature of the cold atom. The number of atoms passing through the microcavity for each release is also counted, and this number changes exponentially along with the atom temperature. Monte Carlo simulations agree closely with the experimental results, and the initial temperature of the cold atom is determined. Compared with the conventional time-of-flight (TOF) method, this approach avoids some uncertainties in the standard TOF and sheds new light on determining temperature of cold atoms by counting atoms individually in a confined space.

  8. Resonance ionization for analytical spectroscopy

    DOE Patents [OSTI]

    Hurst, George S.; Payne, Marvin G.; Wagner, Edward B.

    1976-01-01

    This invention relates to a method for the sensitive and selective analysis of an atomic or molecular component of a gas. According to this method, the desired neutral component is ionized by one or more resonance photon absorptions, and the resultant ions are measured in a sensitive counter. Numerous energy pathways are described for accomplishing the ionization including the use of one or two tunable pulsed dye lasers.

  9. Absorption heat pump system

    DOE Patents [OSTI]

    Grossman, Gershon; Perez-Blanco, Horacio

    1984-01-01

    An improvement in an absorption heat pump cycle is obtained by adding adiabatic absorption and desorption steps to the absorber and desorber of the system. The adiabatic processes make it possible to obtain the highest temperature in the absorber before any heat is removed from it and the lowest temperature in the desorber before heat is added to it, allowing for efficient utilization of the thermodynamic availability of the heat supply stream. The improved system can operate with a larger difference between high and low working fluid concentrations, less circulation losses, and more efficient heat exchange than a conventional system.

  10. Atomic magnetometer

    DOE Patents [OSTI]

    Schwindt, Peter; Johnson, Cort N.

    2012-07-03

    An atomic magnetometer is disclosed which uses a pump light beam at a D1 or D2 transition of an alkali metal vapor to magnetically polarize the vapor in a heated cell, and a probe light beam at a different D2 or D1 transition to sense the magnetic field via a polarization rotation of the probe light beam. The pump and probe light beams are both directed along substantially the same optical path through an optical waveplate and through the heated cell to an optical filter which blocks the pump light beam while transmitting the probe light beam to one or more photodetectors which generate electrical signals to sense the magnetic field. The optical waveplate functions as a quarter waveplate to circularly polarize the pump light beam, and as a half waveplate to maintain the probe light beam linearly polarized.

  11. High resolution absorption spectroscopy of exploding wire plasmas...

    Office of Scientific and Technical Information (OSTI)

    Laboratory of Plasma Studies, Cornell University, 439 Rhodes Hall, Ithaca, New York 14853, USA Sandia National Laboratories, Albuquerque, New Mexico 87185, USA Publication Date: ...

  12. In-situ extended X-ray absorption fine structure study of electrostriction in Gd doped ceria

    SciTech Connect (OSTI)

    Korobko, Roman; Wachtel, Ellen; Lubomirsky, Igor; Lerner, Alyssa; Li, Yuanyuan; Frenkel, Anatoly I.

    2015-01-26

    Studying electric field-induced structural changes in ceramics is challenging due to the very small magnitude of the atomic displacements. We used differential X-ray absorption spectroscopy, an elementally specific and spatially sensitive method, to detect such changes in Gd-doped ceria, recently shown to exhibit giant electrostriction. We found that the large electrostrictive stress generation can be associated with a few percent of unusually short Ce-O chemical bonds that change their length and degree of order under an external electric field. The remainder of the lattice is reduced to the role of passive spectator. This mechanism is fundamentally different from that in electromechanically active materials currently in use.

  13. Method and apparatus for optoacoustic spectroscopy

    DOE Patents [OSTI]

    Amer, Nabil M.

    1979-01-01

    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.

  14. An Atomic-Level Understanding of Copper-Based Catalysts

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

    ... The surface becomes completely unstable at the atomic level, causing it to readily ... in the presence of CO. Ambient-pressure x-ray photoelectron spectroscopy (AP-XPS) at ...

  15. Spectroscopy and isotope shifts of the 4s3d {sup 1}D{sub 2}-4s5p {sup 1}P{sub 1} repumping transition in magneto-optically trapped calcium atoms

    SciTech Connect (OSTI)

    Dammalapati, U.; Norris, I.; Burrows, C.; Arnold, A. S.; Riis, E.

    2010-02-15

    We investigate a repumping scheme for magneto-optically trapped calcium atoms. It is based on excitation of the 4s3d{sup 1}D{sub 2}-4s5p{sup 1}P{sub 1} transition at 672 nm with an extended cavity diode laser. The effect of the repumping is approximately a factor of three increase in trap lifetime and a doubling of the trapping efficiency from a Zeeman slowed thermal beam. Added to this, the 672-nm laser repumps atoms from an otherwise dark state to yield an overall increase in detected fluorescence signal from the magneto-optic trap (MOT) of more than an order of magnitude. Furthermore, we report isotope shift measurements of the 672-nm transition, for the first time, for four naturally occurring even isotopes. Using available charge radii data, the observed shifts, extending up to 4.3 GHz, display the expected linear dependence in a King plot analysis. The measured shifts are used to determine the isotope shifts of the remaining {sup 41,43,46}Ca isotopes. These might be of interest where less abundant isotopes are used enabling isotope selective repumping, resulting in enhanced trapping and detection efficiencies.

  16. Laser-cooled atomic ions as probes of molecular ions

    SciTech Connect (OSTI)

    Brown, Kenneth R.; Viteri, C. Ricardo; Clark, Craig R.; Goeders, James E.; Khanyile, Ncamiso B.; Vittorini, Grahame D.

    2015-01-22

    Trapped laser-cooled atomic ions are a new tool for understanding cold molecular ions. The atomic ions not only sympathetically cool the molecular ions to millikelvin temperatures, but the bright atomic ion fluorescence can also serve as a detector of both molecular reactions and molecular spectra. We are working towards the detection of single molecular ion spectra by sympathetic heating spectroscopy. Sympathetic heating spectroscopy uses the coupled motion of two trapped ions to measure the spectra of one ion by observing changes in the fluorescence of the other ion. Sympathetic heating spectroscopy is a generalization of quantum logic spectroscopy, but does not require ions in the motional ground state or coherent control of the ion internal states. We have recently demonstrated this technique using two isotopes of Ca{sup +} [Phys. Rev. A, 81, 043428 (2010)]. Limits of the method and potential applications for molecular spectroscopy are discussed.

  17. Nanoparticles and nanowires: synchrotron spectroscopy studies

    SciTech Connect (OSTI)

    Sham, T.K.

    2008-08-11

    This paper reviews the research in nanomaterials conducted in our laboratory in the last decade using conventional and synchrotron radiation techniques. While preparative and conventional characterisation techniques are described, emphasis is placed on the analysis of nanomaterials using synchrotron radiation. Materials of primary interests are metal nanoparticles and semiconductor nanowires and nanoribbons. Synchrotron techniques based on absorption spectroscopy such as X-ray absorption fine structures (XAFS), which includes X-ray absorption near edge structures (XANES) and extended X-ray absorption fine structures (EXFAS), and de-excitation spectroscopy, including X-ray excited optical luminescence (XEOL), time-resolved X-ray excited optical luminescence (TRXEOL) and X-ray emission spectroscopy (XES) are described. We show that the tunability, brightness, polarisation and time structure of synchrotron radiation are providing unprecedented capabilities for nanomaterials analysis. Synchrotron studies of prototype systems such as gold nanoparticles, 1-D nanowires of group IV materials, C, Si and Ge as well as nanodiamond, and compound semiconductors, ZnS, CdS, ZnO and related materials are used to illustrate the power and unique capabilities of synchrotron spectroscopy in the characterisation of local structure, electronic structure and optical properties of nanomaterials.

  18. Vapor phase tri-methyl-indium seeding system suitable for high temperature spectroscopy and thermometry

    SciTech Connect (OSTI)

    Whiddon, R.; Zhou, B.; Borggren, J.; Aldén, M.; Li, Z. S.

    2015-09-15

    Tri-methyl-indium (TMI) is used as an indium transport molecule to introduce indium atoms to reactive hot gas flows/combustion environments for spectroscopic diagnostics. A seeding system was constructed to allow the addition of an inert TMI laden carrier gas into an air/fuel mixture burning consequently on a burner. The amount of the seeded TMI in the carrier gas can be readily varied by controlling the vapor pressure through the temperature of the container. The seeding process was calibrated using the fluorescent emission intensity from the indium 6{sup 2}S{sub 1/2} → 5{sup 2}P{sub 1/2} and 6{sup 2}S{sub 1/2} → 5{sup 2}P{sub 3/2} transitions as a function of the calculated TMI seeding concentration over a range of 2–45 ppm. The response was found to be linear over the range 3–22.5 ppm; at concentrations above 25 ppm there is a loss of linearity attributable to self-absorption or loss of saturation of TMI vapor pressure in the carrier gas flow. When TMI was introduced into a post-combustion environment via an inert carrier gas, molecular transition from InH and InOH radicals were observed in the flame emission spectrum. Combined laser-induced fluorescence and absorption spectroscopy were applied to detect indium atoms in the TMI seeded flame and the measured atomic indium concentration was found to be at the ppm level. This method of seeding organometallic vapor like TMI to a reactive gas flow demonstrates the feasibility for quantitative spectroscopic investigations that may be applicable in various fields, e.g., chemical vapor deposition applications or temperature measurement in flames with two-line atomic fluorescence.

  19. THE SPECTRUM OF Fe II (Journal Article) | SciTech Connect

    Office of Scientific and Technical Information (OSTI)

    Subject: 74 ATOMIC AND MOLECULAR PHYSICS; 79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ABSORPTION SPECTRA; ABSORPTION SPECTROSCOPY; ASTROPHYSICS; EDUCATIONAL FACILITIES; ENERGY ...

  20. Coherent population trapping resonances at lower atomic levels of Doppler broadened optical lines

    SciTech Connect (OSTI)

    ?ahin, E; Hamid, R; elik, M; zen, G; Izmailov, A Ch

    2014-11-30

    We have detected and analysed narrow high-contrast coherent population trapping (CPT) resonances, which are induced in absorption of a weak monochromatic probe light beam by counterpropagating two-frequency pump radiation in a cell with rarefied caesium vapour. The experimental investigations have been performed by the example of nonclosed three level ?-systems formed by spectral components of the D{sub 2} line of caesium atoms. The applied method allows one to analyse features of the CPT phenomenon directly at a given low long-lived level of the selected ?-system even in sufficiently complicated spectra of atomic gases with large Doppler broadening. We have established that CPT resonances in transmission of the probe beam exhibit not only a higher contrast but also a much lesser width in comparison with well- known CPT resonances in transmission of the corresponding two-frequency pump radiation. The results obtained can be used in selective photophysics, photochemistry and ultra-high resolution atomic (molecular) spectroscopy. (laser applications and other topics in quantum electronics)

  1. Dirac Charge Dynamcs in Graphene by Infrared Spectroscopy

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

  2. Dirac Charge Dynamcs in Graphene by Infrared Spectroscopy

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

    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...

  3. Atomic Chemistry in Turbulent Media I: Effect of Atomic Cooling...

    Office of Scientific and Technical Information (OSTI)

    Atomic Chemistry in Turbulent Media I: Effect of Atomic Cooling Citation Details In-Document Search Title: Atomic Chemistry in Turbulent Media I: Effect of Atomic Cooling Authors: ...

  4. Ultraviolet absorption hygrometer

    DOE Patents [OSTI]

    Gersh, Michael E.; Bien, Fritz; Bernstein, Lawrence S.

    1986-01-01

    An ultraviolet absorption hygrometer is provided including a source of pulsed ultraviolet radiation for providing radiation in a first wavelength region where water absorbs significantly and in a second proximate wavelength region where water absorbs weakly. Ultraviolet radiation in the first and second regions which has been transmitted through a sample path of atmosphere is detected. The intensity of the radiation transmitted in each of the first and second regions is compared and from this comparison the amount of water in the sample path is determined.

  5. Ultraviolet absorption hygrometer

    DOE Patents [OSTI]

    Gersh, M.E.; Bien, F.; Bernstein, L.S.

    1986-12-09

    An ultraviolet absorption hygrometer is provided including a source of pulsed ultraviolet radiation for providing radiation in a first wavelength region where water absorbs significantly and in a second proximate wavelength region where water absorbs weakly. Ultraviolet radiation in the first and second regions which has been transmitted through a sample path of atmosphere is detected. The intensity of the radiation transmitted in each of the first and second regions is compared and from this comparison the amount of water in the sample path is determined. 5 figs.

  6. Atom Trajectory Viewer

    Energy Science and Technology Software Center (OSTI)

    2015-12-28

    Atom Trajectory Viewer is a visualization tool developed to enable interactive exploration of atomic trajectories and corresponding statistics in molecular dynamics.

  7. Isotope Enrichment Detection by Laser Ablation - Dual Tunable Diode Laser Absorption Spectrometry

    SciTech Connect (OSTI)

    Anheier, Norman C.; Bushaw, Bruce A.

    2009-07-01

    The rapid global expansion of nuclear energy is motivating the expedited development of new safeguards technology to mitigate potential proliferation threats arising from monitoring gaps within the uranium enrichment process. Current onsite enrichment level monitoring methods are limited by poor sensitivity and accuracy performance. Offsite analysis has better performance, but this approach requires onsite hand sampling followed by time-consuming and costly post analysis. These limitations make it extremely difficult to implement comprehensive safeguards accounting measures that can effectively counter enrichment facility misuse. In addition, uranium enrichment by modern centrifugation leads to a significant proliferation threat, since the centrifuge cascades can quickly produce a significant quantity of highly enriched uranium (HEU). The Pacific Northwest National Laboratory is developing an engineered safeguards approach having continuous aerosol particulate collection and uranium isotope analysis to provide timely detection of HEU production in a low enriched uranium facility. This approach is based on laser vaporization of aerosol particulate samples, followed by wavelength tuned laser diode spectroscopy, to characterize the 235U/238U isotopic ratio by subtle differences in atomic absorption wavelengths arising from differences in each isotopes nuclear mass, volume, and spin (hyperfine structure for 235U). Environmental sampling media is introduced into a small, reduced pressure chamber, where a focused pulsed laser vaporizes a 10 to 20-m sample diameter. The ejected plasma forms a plume of atomic vapor. A plume for a sample containing uranium has atoms of the 235U and 238U isotopes present. Tunable diode lasers are directed through the plume to selectively excite each isotope and their presence is detected by monitoring absorbance signals on a shot-to-shot basis. Single-shot detection sensitivity approaching the femtogram range and abundance uncertainty less

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

    SciTech Connect (OSTI)

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

    2015-07-15

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

  9. Method of trivalent chromium concentration determination by atomic spectrometry

    DOE Patents [OSTI]

    Reheulishvili, Aleksandre N.; Tsibakhashvili, Neli Ya.

    2006-12-12

    A method is disclosed for determining the concentration of trivalent chromium Cr(III) in a sample. The addition of perchloric acid has been found to increase the atomic chromium spectrometric signal due to Cr(III), while leaving the signal due to hexavalent chromium Cr(VI) unchanged. This enables determination of the Cr(III) concentration without pre-concentration or pre-separation from chromium of other valences. The Cr(III) concentration may be measured using atomic absorption spectrometry, atomic emission spectrometry or atomic fluorescence spectrometry.

  10. Observation by two-photon laser spectroscopy of the 4d{sup 10}5s {sup 2}S{sub 1/2}{yields}4d{sup 9}5s{sup 2} {sup 2}D{sub 5/2} clock transition in atomic silver

    SciTech Connect (OSTI)

    Badr, T.; Plimmer, M. D.; Juncar, P.; Himbert, M. E.; Louyer, Y.; Knight, D. J. E.

    2006-12-15

    We report the observation of the very narrow 4d{sup 10}5s {sup 2}S{sub 1/2}{yields}4d{sup 9}5s{sup 2} {sup 2}D{sub 5/2} transition in atomic silver. The frequencies of the hyperfine components in {sup 107}Ag and {sup 109}Ag have been measured using Doppler-free two-photon laser spectroscopy of a thermal beam and heterodyne calibration with respect to the a{sub 1} component of the 62P(4-5) line in molecular iodine near 661 nm. For the center of gravity of a mixture of natural abundance, we deduce the value 906 641 295.77(19) MHz. For the isotope shift, we obtain {nu}({sup 109}Ag)-{nu}({sup 107}Ag)=564.15(37) MHz, from which we deduce the frequency and isotope shift of the 4d{sup 10}5s {sup 2}S{sub 1/2}{yields}4d{sup 10}6p {sup 2}P{sub 3/2} transition at 206 nm.

  11. X-ray and vibrational spectroscopy of manganese complexes relevant to the oxygen-evolving complex of photosynthesis

    SciTech Connect (OSTI)

    Visser, Hendrik

    2001-05-16

    Manganese model complexes, relevant to the oxygen-evolving complex (OEC) in photosynthesis, were studied with Mn K-edge X-ray absorption near-edge spectroscopy (XANES), Mn Kb X-ray emission spectroscopy (XES), and vibrational spectroscopy. A more detailed understanding was obtained of the influence of nuclearity, overall structure, oxidation state, and ligand environment of the Mn atoms on the spectra from these methods. This refined understanding is necessary for improving the interpretation of spectra of the OEC. Mn XANES and Kb XES were used to study a di-(mu)-oxo and a mono-(mu)-oxo di-nuclear Mn compound in the (III,III), (III,IV), and (IV,IV) oxidation states. XANES spectra show energy shifts of 0.8 - 2.2 eV for 1-electron oxidation-state changes and 0.4 - 1.8 eV for ligand-environment changes. The shifts observed for Mn XES spectra were approximately 0.21 eV for oxidation state-changes and only approximately 0.04 eV for ligand-environment changes. This indicates that Mn Kb XES i s more sensitive to the oxidation state and less sensitive to the ligand environment of the Mn atoms than XANES. These complimentary methods provide information about the oxidation state and the ligand environment of Mn atoms in model compounds and biological systems. A versatile spectroelectrochemical apparatus was designed to aid the interpretation of IR spectra of Mn compounds in different oxidation states. The design, based on an attenuated total reflection device, permits the study of a wide spectral range: 16,700 (600 nm) - 225

  12. Matrix isolation sublimation: An apparatus for producing cryogenic beams of atoms and molecules

    SciTech Connect (OSTI)

    Sacramento, R. L.; Alves, B. X.; Silva, B. A.; Wolff, W.; Cesar, C. L.; Oliveira, A. N.; Li, M. S.

    2015-07-15

    We describe the apparatus to generate cryogenic beams of atoms and molecules based on matrix isolation sublimation. Isolation matrices of Ne and H{sub 2} are hosts for atomic and molecular species which are sublimated into vacuum at cryogenic temperatures. The resulting cryogenic beams are used for high-resolution laser spectroscopy. The technique also aims at loading atomic and molecular traps.

  13. A modular reactor design for in situ synchrotron x-ray investigation of atomic layer deposition processes

    SciTech Connect (OSTI)

    Klug, Jeffrey A. Emery, Jonathan D.; Martinson, Alex B. F.; Proslier, Thomas; Weimer, Matthew S.; Yanguas-Gil, Angel; Elam, Jeffrey W.; Seifert, Sönke; Schlepütz, Christian M.; Hock, Adam S.

    2015-11-15

    Synchrotron characterization techniques provide some of the most powerful tools for the study of film structure and chemistry. The brilliance and tunability of the Advanced Photon Source allow access to scattering and spectroscopic techniques unavailable with in-house laboratory setups and provide the opportunity to probe various atomic layer deposition (ALD) processes in situ starting at the very first deposition cycle. Here, we present the design and implementation of a portable ALD instrument which possesses a modular reactor scheme that enables simple experimental switchover between various beamlines and characterization techniques. As first examples, we present in situ results for (1) X-ray surface scattering and reflectivity measurements of epitaxial ZnO ALD on sapphire, (2) grazing-incidence small angle scattering of MnO nucleation on silicon, and (3) grazing-incidence X-ray absorption spectroscopy of nucleation-regime Er{sub 2}O{sub 3} ALD on amorphous ALD alumina and single crystalline sapphire.

  14. A modular reactor design for in situ synchrotron X-ray investigation of atomic layer deposition processes

    SciTech Connect (OSTI)

    Klug, Jeffrey A.; Weimer, Matthew S.; Emery, Jonathan D.; Yanguas-Gil, Angel; Seifert, Sonke; Schleputz, Christian M.; Martinson, Alex B. F.; Elam, Jeffrey W.; Hock, Adam S.; Proslier, Thomas

    2015-11-01

    Synchrotron characterization techniques provide some of the most powerful tools for the study of film structure and chemistry. The brilliance and tunability of the Advanced Photon Source allow access to scattering and spectroscopic techniques unavailable with in-house laboratory setups and provide the opportunity to probe various atomic layer deposition (ALD) processes in situ starting at the very first deposition cycle. Here, we present the design and implementation of a portable ALD instrument which possesses a modular reactor scheme that enables simple experimental switchover between various beamlines and characterization techniques. As first examples, we present \\textit{in situ} results for 1.) X-ray surface scattering and reflectivity measurements of epitaxial ZnO ALD on sapphire, 2.) grazing-incidence small angle scattering of MnO nucleation on silicon, and 3.) grazing-incidence X-ray absorption spectroscopy of nucleation-regime Er2O3 ALD on amorphous ALD alumina and single crystalline sapphire.

  15. Analysis of a magnetically trapped atom clock

    SciTech Connect (OSTI)

    Kadio, D.; Band, Y. B.

    2006-11-15

    We consider optimization of a rubidium atom clock that uses magnetically trapped Bose condensed atoms in a highly elongated trap, and determine the optimal conditions for minimum Allan variance of the clock using microwave Ramsey fringe spectroscopy. Elimination of magnetic field shifts and collisional shifts are considered. The effects of spin-dipolar relaxation are addressed in the optimization of the clock. We find that for the interstate interaction strength equal to or larger than the intrastate interaction strengths, a modulational instability results in phase separation and symmetry breaking of the two-component condensate composed of the ground and excited hyperfine clock levels, and this mechanism limits the clock accuracy.

  16. Strontium Iodide Instrument Development for Gamma Spectroscopy and Radioisotope Identification

    SciTech Connect (OSTI)

    Beck, P; Cherepy, Nerine; Payne, Stephen A.; Swanberg, E.; Nelson, K.; Thelin, P; Fisher, S E; Hunter, Steve; Wihl, B; Shah, Kanai; Hawrami, Rastgo; Burger, Arnold; Boatner, Lynn A; Momayezi, M; Stevens, K; Randles, M H; Solodovnikov, D

    2014-01-01

    Development of the Europium-doped Strontium Iodide scintillator, SrI2(Eu), has progressed significantly in recent years. SrI2(Eu) has excellent material properties for gamma ray spectroscopy: high light yield (>80,000 ph/MeV), excellent light yield proportionality, and high effective atomic number (Z=49) for high photoelectric cross-section. High quality 1.5 and 2 diameter boules are now available due to rapid advances in SrI2(Eu) crystal growth. In these large SrI2(Eu) crystals, optical self-absorption by Eu2+ degrades the energy resolution as measured by analog electronics, but we mitigate this effect through on-the-fly correction of the scintillation pulses by digital readout electronics. Using this digital correction technique we have demonstrated energy resolution of 2.9% FWHM at 662 keV for a 4 in3 SrI2(Eu) crystal, over 2.6 inches long. Based on this digital readout technology, we have developed a detector prototype with greatly improved radioisotope identification capability compared to Sodium Iodide, NaI(Tl). The higher resolution of SrI2(Eu) yields a factor of 2 to 5 improvement in radioisotope identification (RIID) error rate compared to NaI(Tl).

  17. Performance and analysis of absorption experiments on x-ray heated low-Z constrained samples

    SciTech Connect (OSTI)

    Lee, R.W.; Cauble, R.; Perry, T.S.; Springer, P.T.; Fields, D.F.; Bach, D.R.; Serduke, F.J.D.; Iglesias, C.A.; Rogers, F.J.; Nash, J.K.; Chen, M.H.; Wilson, B.G.; Goldstein, W.H.; Ward, R.A.; Kilkenny, J.D.; Doyas, R.; Da Silva, L.B.; Back, C.A.; Davidson, S.J.; Foster, J.M.; Smith, C.C.

    1996-05-01

    Results of experiments on the absorption of niobium in a hot, dense plasma are presented. These results represent a major step in the development of absorption techniques necessary for the quantitative characterization of hot, dense matter. A general discussion is presented of the requirements for performing quantitative analysis of absorption spectra. Hydrodynamic simulations are used to illustrate the behavior of tamped X-ray-heated matter and to indicate effects that can arise from the two dimensional aspects of the experiment. The absorption spectrum of a low-Z material, in this case aluminum, provides a temperature diagnostic and indicates the advance of the absorption measurement technique to the level of application. The experimental technique is placed in context with a review of other measurements using absorption spectroscopy to probe hot, dense matter.

  18. Tunable enhanced optical absorption of graphene using plasmonic perfect absorbers

    SciTech Connect (OSTI)

    Cai, Yijun; Zhu, Jinfeng; Liu, Qing Huo

    2015-01-26

    Enhancement and manipulation of light absorption in graphene is a significant issue for applications of graphene-based optoelectronic devices. In order to achieve this purpose in the visible region, we demonstrate a design of a graphene optical absorber inspired by metal-dielectric-metal metamaterial for perfect absorption of electromagnetic waves. The optical absorbance ratios of single and three atomic layer graphene are enhanced up to 37.5% and 64.8%, respectively. The graphene absorber shows polarization-dependence and tolerates a wide range of incident angles. Furthermore, the peak position and bandwidth of graphene absorption spectra are tunable in a wide wavelength range through a specific structural configuration. These results imply that graphene in combination with plasmonic perfect absorbers have a promising potential for developing advanced nanophotonic devices.

  19. Gas-absorption process

    DOE Patents [OSTI]

    Stephenson, Michael J.; Eby, Robert S.

    1978-01-01

    This invention is an improved gas-absorption process for the recovery of a desired component from a feed-gas mixture containing the same. In the preferred form of the invention, the process operations are conducted in a closed-loop system including a gas-liquid contacting column having upper, intermediate, and lower contacting zones. A liquid absorbent for the desired component is circulated through the loop, being passed downwardly through the column, regenerated, withdrawn from a reboiler, and then recycled to the column. A novel technique is employed to concentrate the desired component in a narrow section of the intermediate zone. This technique comprises maintaining the temperature of the liquid-phase input to the intermediate zone at a sufficiently lower value than that of the gas-phase input to the zone to effect condensation of a major part of the absorbent-vapor upflow to the section. This establishes a steep temperature gradient in the section. The stripping factors below this section are selected to ensure that virtually all of the gases in the downflowing absorbent from the section are desorbed. The stripping factors above the section are selected to ensure re-dissolution of the desired component but not the less-soluble diluent gases. As a result, a peak concentration of the desired component is established in the section, and gas rich in that component can be withdrawn therefrom. The new process provides important advantages. The chief advantage is that the process operations can be conducted in a single column in which the contacting zones operate at essentially the same pressure.

  20. Characterization of the Electronic Structure of Silicon Nanoparticles Using X-ray Absorption and Emission

    SciTech Connect (OSTI)

    Vaverka, A M

    2008-07-15

    Resolving open questions regarding transport in nanostructures can have a huge impact on a broad range of future technologies such as light harvesting for energy. Silicon has potential to be used in many of these applications. Understanding how the band edges of nanostructures move as a function of size, surface termination and assembly is of fundamental importance in understanding the transport properties of these materials. In this thesis work I have investigated the change in the electronic structure of silicon nanoparticle assemblies as the surface termination is changed. Nanoparticles are synthesized using a thermal evaporation technique and sizes are determined using atomic force microscopy (AFM). By passivating the particles with molecules containing alcohol groups we are able to modify the size dependent band edge shifts. Both the valence and conduction bands are measured using synchrotron based x-ray absorption spectroscopy (XAS) and soft x-ray fluorescence (SXF) techniques. Particles synthesized via recrystallization of amorphous silicon/SiO{sub 2} multilayers of thicknesses below 10 nm are also investigated using the synchrotron techniques. These samples also show quantum confinement effects but the electronic structure is different from those synthesized via evaporation methods. The total bandgap is determined for all samples measured. The origins of these differences in the electronic structures are discussed.

  1. Atomizing nozzle and process

    DOE Patents [OSTI]

    Anderson, Iver E.; Figliola, Richard S.; Molnar, Holly M.

    1993-07-20

    High pressure atomizing nozzle includes a high pressure gas manifold having a divergent expansion chamber between a gas inlet and arcuate manifold segment to minimize standing shock wave patterns in the manifold and thereby improve filling of the manifold with high pressure gas for improved melt atomization. The atomizing nozzle is especially useful in atomizing rare earth-transition metal alloys to form fine powder particles wherein a majority of the powder particles exhibit particle sizes having near-optimum magnetic properties.

  2. Atomizing nozzle and process

    DOE Patents [OSTI]

    Anderson, Iver E.; Figliola, Richard S.; Molnar, Holly M.

    1992-06-30

    High pressure atomizing nozzle includes a high pressure gas manifold having a divergent expansion chamber between a gas inlet and arcuate manifold segment to minimize standing shock wave patterns in the manifold and thereby improve filling of the manifold with high pressure gas for improved melt atomization. The atomizing nozzle is especially useful in atomizing rare earth-transition metal alloys to form fine powder particles wherein a majority of the powder particles exhibit particle sizes having near-optimum magnetic properties.

  3. L. James Rainwater and the Atomic Nuclei

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

    L. James Rainwater and the Atomic Nucleus Resources with Additional Information James Rainwater Courtesy AIP Emilio Segre Visual Archives, W. F. Meggers Gallery of Nobel Laureates "During W.W. II, I [James Rainwater] worked ... [on the] Manhattan Project, mainly doing pulsed neutron spectroscopy using the small Columbia cyclotron. ... [Maria Geoppert-Mayer] shell model suggestion in 1949 was a great triumph and fitted my belief that a nuclear shell model should represent a proper approach

  4. Atomic Energy Commission Takes Over Responsibility for all Atomic...

    National Nuclear Security Administration (NNSA)

    Takes Over Responsibility for all Atomic Energy Programs Atomic Energy Commission Takes Over Responsibility for all Atomic Energy Program Washington, DC In accordance with the ...

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

    SciTech Connect (OSTI)

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

    2015-02-09

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

  6. High effective atomic number polymer scintillators for gamma ray spectroscopy

    DOE Patents [OSTI]

    Cherepy, Nerine Jane; Sanner, Robert Dean; Payne, Stephen Anthony; Rupert, Benjamin Lee; Sturm, Benjamin Walter

    2014-04-15

    A scintillator material according to one embodiment includes a bismuth-loaded aromatic polymer having an energy resolution at 662 keV of less than about 10%. A scintillator material according to another embodiment includes a bismuth-loaded aromatic polymer having a fluor incorporated therewith and an energy resolution at 662 keV of less than about 10%. Additional systems and methods are also presented.

  7. Scanning tunneling spectroscopy of a magnetic atom on graphene...

    Office of Scientific and Technical Information (OSTI)

    Visit OSTI to utilize additional information resources in energy science and technology. A ... By using the non-equilibrium Green function method with the slave-boson mean field ...

  8. Scanning tunneling spectroscopy of a magnetic atom on graphene...

    Office of Scientific and Technical Information (OSTI)

    Show Author Affiliations Chinese Academy of Sciences (CAS), Beijing (China) Chinese Academy of Sciences (CAS), Beijing (China); Oklahoma State Univ., Stillwater, OK (United States) ...

  9. Scanning tunneling spectroscopy of a magnetic atom on graphene...

    Office of Scientific and Technical Information (OSTI)

    In this study, the Kondo effect in the system consisting of a magnetic adatom on the graphene is studied. By using the non-equilibrium Green function method with the slave-boson ...

  10. Scanning tunneling spectroscopy of a magnetic atom on graphene...

    Office of Scientific and Technical Information (OSTI)

    By using the non-equilibrium Green function method with the slave-boson mean field ... But for the undoped graphene, the Kondo phase only exists if the adatom's energy level is ...

  11. The rediscovery of absorption chillers

    SciTech Connect (OSTI)

    Katzel, J.

    1992-04-23

    Absorption chillers are back - and for two very good reasons: they are environmentally sound and, in many cases, economically attractive. One factor fueling this resurgence is the outlook for natural gas, the energy source of most absorption systems. Deregulation has spurred exploration, and forecasts indicate an abundant supply and relatively low prices through 2050. Threats of global warming and depletion of the ozone layer also are forces driving the absorption chiller market. Being a good corporate citizen today means minimizing or eliminating the use of chlorofluorocarbons (CFCs), the basis of many refrigerants used in mechanical chillers. Even as chemical and chiller manufacturers alike work to develop substitute refrigerants, the perfect alternative has yet to be found. Absorption units are free of these problems, a benefit that appeals to many people.

  12. Atomic Energy Commission : Atomic Power at Shippingport - 1958 Educational Film

    SciTech Connect (OSTI)

    2013-02-02

    The United States Atomic Energy Commission & Westinghouse Electric Company take us on a tour of an atomic power station.

  13. PARTICLE ACCELERATORS; 74 ATOMIC AND MOLECULAR PHYSICS; ATOMS...

    Office of Scientific and Technical Information (OSTI)

    74 ATOMIC AND MOLECULAR PHYSICS; ATOMS; ELECTRONS; HELIUM; LIGHT SOURCES; RADIATIONS; STORAGE RINGS; SYNCHROTRONS SYNCHROTRON RADIATION SYNCHROTRONLIGHT SOURCES QUANTUM CHAOS...

  14. Atomic Energy Commission : Atomic Power at Shippingport - 1958 Educational Film

    ScienceCinema (OSTI)

    None

    2014-07-31

    The United States Atomic Energy Commission & Westinghouse Electric Company take us on a tour of an atomic power station.

  15. Absorption Heat Pumps | Department of Energy

    Energy Savers [EERE]

    Heat Pump Systems Absorption Heat Pumps Absorption Heat Pumps Absorption heat pumps are ... As in a standard heat pump, the refrigerant (in this case, ammonia) is condensed in one ...

  16. Atomic Energy Commission Takes Over Responsibility for all Atomic Energy

    National Nuclear Security Administration (NNSA)

    Programs | National Nuclear Security Administration | (NNSA) Takes Over Responsibility for all Atomic Energy Programs Atomic Energy Commission Takes Over Responsibility for all Atomic Energy Program Washington, DC In accordance with the Atomic Energy Act of 1946, all atomic energy activities are transferred to the newly created Atomic Energy Commission

  17. Heterodyne laser spectroscopy system

    DOE Patents [OSTI]

    Wyeth, Richard W.; Paisner, Jeffrey A.; Story, Thomas

    1989-01-01

    A heterodyne laser spectroscopy system utilizes laser heterodyne techniques for purposes of laser isotope separation spectroscopy, vapor diagnostics, processing of precise laser frequency offsets from a reference frequency and the like, and provides spectral analysis of a laser beam.

  18. Heterodyne laser spectroscopy system

    DOE Patents [OSTI]

    Wyeth, Richard W.; Paisner, Jeffrey A.; Story, Thomas

    1990-01-01

    A heterodyne laser spectroscopy system utilizes laser heterodyne techniques for purposes of laser isotope separation spectroscopy, vapor diagnostics, processing of precise laser frequency offsets from a reference frequency, and provides spectral analysis of a laser beam.

  19. Mechanical properties and energy absorption characteristics of...

    Office of Scientific and Technical Information (OSTI)

    Mechanical properties and energy absorption characteristics of a polyurethane foam Citation Details In-Document Search Title: Mechanical properties and energy absorption ...

  20. Metal atom oxidation laser

    DOE Patents [OSTI]

    Jensen, R.J.; Rice, W.W.; Beattie, W.H.

    1975-10-28

    A chemical laser which operates by formation of metal or carbon atoms and reaction of such atoms with a gaseous oxidizer in an optical resonant cavity is described. The lasing species are diatomic or polyatomic in nature and are readily produced by exchange or other abstraction reactions between the metal or carbon atoms and the oxidizer. The lasing molecules may be metal or carbon monohalides or monoxides. (auth)

  1. Metal atom oxidation laser

    DOE Patents [OSTI]

    Jensen, R.J.; Rice, W.W.; Beattie, W.H.

    1975-10-28

    A chemical laser which operates by formation of metal or carbon atoms and reaction of such atoms with a gaseous oxidizer in an optical resonant cavity is described. The lasing species are diatomic or polyatomic in nature and are readily produced by exchange or other abstraction reactions between the metal or carbon atoms and the oxidizer. The lasing molecules may be metal or carbon monohalides or monoxides.

  2. The Harnessed Atom

    Broader source: Energy.gov [DOE]

    The Harnessed Atom is a new middle school science, technology, engineering, and math (STEM) curriculum extension that focuses on nuclear science and energy. It offers teachers accurate, unbiased,...

  3. 44th Annual Anomalous Absorption Conference

    SciTech Connect (OSTI)

    Beg, Farhat

    2014-03-03

    Conference Grant Report July 14, 2015 Submitted to the U. S. Department of Energy Attn: Dr. Sean Finnegan By the University of California, San Diego 9500 Gilman Drive La Jolla, California 92093 On behalf of the 44th Annual Anomalous Absorption Conference 8-13 June 2014, in Estes Park, Colorado Support Requested: $10,100 Amount expended: $3,216.14 Performance Period: 1 March 20 14 to 28 February 20 15 Principal Investigator Dr. Farhat Beg Center for Energy Research University of California, San Diego 9500 Gilman Drive La Jolla, California 92093-0417 858-822-1266 (telephone) 858-534-4543 (fax) fbeg@ucsd.edu Administrative Point of Contact: Brandi Pate, 858-534-0851, blpate®ucsd.edu I. Background The forty-fourth Anomalous Absorption Conference was held in Estes Park, Colorado from June 5-8, 2014 (aac2014.ucsd.edu). The first Anomalous Absorption Conference was held in 1971 to assemble experts in the poorly understood area of laser-plasma absorption. The goal of that conference was to address the anomalously large laser absorption seen in plasma experiments with respect to the laser absorption predicted by linear plasma theory. Great progress in this research area has been made in the decades since that first meeting, due in part to the scientific interactions that have occurred annually at this conference. Specifically, this includes the development of nonlinear laser-plasma theory and the simulation of laser interactions with plasmas. Each summer since that first meeting, this week-long conference has been held at unique locations in North America as a scientific forum for intense scientific exchanges relevant to the interaction of laser radiation with plasmas. Responsibility for organizing the conference has traditional rotated each year between the major Inertial Confinement Fusion (ICF) laboratories and universities including LANL, LLNL, LLE, UCLA UC Davis and NRL. As the conference has matured over the past four decades, its technical footprint has expanded

  4. Atomic structure of nanometer-sized amorphous TiO2

    SciTech Connect (OSTI)

    Zhang, H.; Chen, B.; Banfield, J.F.; Waychunas, G.A.

    2008-10-15

    Amorphous titania (TiO{sub 2}) is an important precursor for synthesis of single-phase nanocrystalline anatase. We synthesized x-ray amorphous titania by hydrolysis of titanium ethoxide at the ice point. Transmission electron microscopy examination and nitrogen gas adsorption indicated the particle size of the synthesized titania is {approx} 2 nm. Synchrotron wide-angle x-ray scattering (WAXS) was used to probe the atomic correlations in this amorphous sample. Atomic pair-distribution function (PDF) derived from Fourier transform of the WAXS data was used for reverse Monte Carlo (RMC) simulations of the atomic structure of the amorphous TiO{sub 2} nanoparticles. Molecular dynamics simulations were used to generate input structures for the RMC. X-ray absorption spectroscopy (XAS) simulations were used to screen candidate structures obtained from the RMC by comparing with experimental XAS data. The structure model that best describes both the WAXS and XAS data shows that an amorphous TiO{sub 2} particle consists of a highly distorted shell and a small strained anatase-like crystalline core. The average coordination number of Ti is 5.3 and most Ti-O bonds are populated around 1.940 {angstrom}. Relative to bulk TiO{sub 2}, the reduction of the coordination number is primarily due to the truncation of the Ti-O octahedra at the amorphous nanoparticle surface and the shortening of the Ti-O bond length to the bond contraction in the distorted shell. The preexistence of the anatase-like core may be critical to the formation of single-phase nanocrystalline anatase in crystallization of amorphous TiO{sub 2} upon heating.

  5. Mechanistic study of atomic layer deposition of Al{sub x}Si{sub...

    Office of Scientific and Technical Information (OSTI)

    of Alsub xSisub yO thin film via in-situ FTIR spectroscopy Citation Details In-Document Search Title: Mechanistic study of atomic layer deposition of Alsub xSisub yO ...

  6. Modified Embedded Atom Method

    Energy Science and Technology Software Center (OSTI)

    2012-08-01

    Interatomic force and energy calculation subroutine to be used with the molecular dynamics simulation code LAMMPS (Ref a.). The code evaluated the total energy and atomic forces (energy gradient) according to a cubic spline-based variant (Ref b.) of the Modified Embedded Atom Method (MEAM) with a additional Stillinger-Weber (SW) contribution.

  7. Absorption-heat-pump system

    DOE Patents [OSTI]

    Grossman, G.; Perez-Blanco, H.

    1983-06-16

    An improvement in an absorption heat pump cycle is obtained by adding adiabatic absorption and desorption steps to the absorber and desorber of the system. The adiabatic processes make it possible to obtain the highest temperature in the absorber before any heat is removed from it and the lowest temperature in the desorber before heat is added to it, allowing for efficient utilization of the thermodynamic availability of the heat supply stream. The improved system can operate with a larger difference between high and low working fluid concentrations, less circulation losses, and more efficient heat exchange than a conventional system.

  8. Infrared study on room-temperature atomic layer deposition of HfO{sub 2} using tetrakis(ethylmethylamino)hafnium and remote plasma-excited oxidizing agents

    SciTech Connect (OSTI)

    Kanomata, Kensaku [Graduate School of Science and Engineering, Yamagata University, 4-3-16 Jonan, Yonezawa 992-8510, Japan and Japan Society for the Promotion of Science, 5-3-1 Kojimachi, Chiyoda-ku, Tokyo 102-0083 (Japan); Ohba, Hisashi; Pungboon Pansila, P.; Ahmmad, Bashir; Kubota, Shigeru; Hirahara, Kazuhiro; Hirose, Fumihiko, E-mail: fhirose@yz.yamagata-u.ac.jp [Graduate School of Science and Engineering, Yamagata University, 4-3-16 Jonan, Yonezawa 992-8510 (Japan)

    2015-01-01

    Room-temperature atomic layer deposition (ALD) of HfO{sub 2} was examined using tetrakis (ethylmethylamino)hafnium (TEMAH) and remote plasma-excited water and oxygen. A growth rate of 0.26?nm/cycle at room temperature was achieved, and the TEMAH adsorption and its oxidization on HfO{sub 2} were investigated by multiple internal reflection infrared absorption spectroscopy. It was observed that saturated adsorption of TEMAH occurs at exposures of ?1??10{sup 5}?L (1 L?=?1??10{sup ?6} Torr s) at room temperature, and the use of remote plasma-excited water and oxygen vapor is effective in oxidizing the TEMAH molecules on the HfO{sub 2} surface, to produce OH sites. The infrared study suggested that HfOH plays a role as an adsorption site for TEMAH. The reaction mechanism of room temperature HfO{sub 2} ALD is discussed in this paper.

  9. Dirac Charge Dynamcs in Graphene by Infrared Spectroscopy

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

    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

  10. Atomic ionization by keV-scale pseudoscalar dark-matter particles

    SciTech Connect (OSTI)

    Dzuba, V. A.; Flambaum, V. V.; Pospelov, M.

    2010-05-15

    Using the relativistic Hartree-Fock approximation, we calculate the rates of atomic ionization by absorption of pseudoscalar particles in the mass range from 10 to {approx}50 keV. We present numerical results for atoms relevant for the direct dark-matter searches (e.g. Ar, Ge, I and Xe), as well as the analytical formula which fits numerical calculations with few per cent accuracy and may be used for multielectron atoms, molecules and condensed matter systems.

  11. Spectroscopy, Kinetics, and Dynamics of Combustion Radicals

    SciTech Connect (OSTI)

    Nesbitt, David J.

    2013-08-06

    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.

  12. CNEEC - Atomic Layer Deposition Tutorial by Stacey Bent

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

    Atomic Layer Deposition

  13. Atomizing nozzle and method

    DOE Patents [OSTI]

    Ting, Jason (Ames, IA); Anderson, Iver E. (Ames, IA); Terpstra, Robert L. (Ames, IA)

    2000-03-16

    A high pressure close-coupled gas atomizing nozzle includes multiple discrete gas jet discharge orifices having aerodynamically designed convergent-divergent geometry with an first converging section communicated to a gas supply manifold and to a diverging section by a constricted throat section to increase atomizing gas velocity. The gas jet orifices are oriented at gas jet apex angle selected relative to the melt supply tip apex angle to establish a melt aspiration condition at the melt supply tip.

  14. Optical atomic magnetometer

    DOE Patents [OSTI]

    Budker, Dmitry; Higbie, James; Corsini, Eric P

    2013-11-19

    An optical atomic magnetometers is provided operating on the principles of nonlinear magneto-optical rotation. An atomic vapor is optically pumped using linearly polarized modulated light. The vapor is then probed using a non-modulated linearly polarized light beam. The resulting modulation in polarization angle of the probe light is detected and used in a feedback loop to induce self-oscillation at the resonant frequency.

  15. Metal atomization spray nozzle

    DOE Patents [OSTI]

    Huxford, T.J.

    1993-11-16

    A spray nozzle for a magnetohydrodynamic atomization apparatus has a feed passage for molten metal and a pair of spray electrodes mounted in the feed passage. The electrodes, diverging surfaces which define a nozzle throat and diverge at an acute angle from the throat. Current passes through molten metal when fed through the throat which creates the Lorentz force necessary to provide atomization of the molten metal. 6 figures.

  16. Metal atomization spray nozzle

    DOE Patents [OSTI]

    Huxford, Theodore J.

    1993-01-01

    A spray nozzle for a magnetohydrodynamic atomization apparatus has a feed passage for molten metal and a pair of spray electrodes mounted in the feed passage. The electrodes, diverging surfaces which define a nozzle throat and diverge at an acute angle from the throat. Current passes through molten metal when fed through the throat which creates the Lorentz force necessary to provide atomization of the molten metal.

  17. Absorption Heat Pumps | Department of Energy

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

    Heat Pump Systems » Absorption Heat Pumps Absorption Heat Pumps Absorption heat pumps are essentially air-source heat pumps driven not by electricity, but by a heat source such as natural gas, propane, solar-heated water, or geothermal-heated water. Because natural gas is the most common heat source for absorption heat pumps, they are also referred to as gas-fired heat pumps. There are also absorption (or gas-fired) coolers available that work on the same principle. Unlike some absorption heat

  18. Photodetector with enhanced light absorption

    DOE Patents [OSTI]

    Kane, James

    1985-01-01

    A photodetector including a light transmissive electrically conducting layer having a textured surface with a semiconductor body thereon. This layer traps incident light thereby enhancing the absorption of light by the semiconductor body. A photodetector comprising a textured light transmissive electrically conducting layer of SnO.sub.2 and a body of hydrogenated amorphous silicon has a conversion efficiency about fifty percent greater than that of comparative cells. The invention also includes a method of fabricating the photodetector of the invention.

  19. GAX absorption cycle design process

    SciTech Connect (OSTI)

    Priedeman, D.K.; Christensen, R.N.

    1999-07-01

    This paper presents an absorption system design process that relies on computer simulations that are validated by experimental findings. An ammonia-water absorption heat pump cycle at 3 refrigeration tons (RT) and chillers at 3.3 RT and 5 RT (10.5 kW, 11.6 kW, and 17.6 kW) were initially modeled and then built and tested. The experimental results were used to calibrate both the cycle simulation and the component simulations, yielding computer design routines that could accurately predict component and cycle performance. Each system was a generator-absorber heat exchange (GAX) cycle, and all were sized for residential and light commercial use, where very little absorption equipment is currently used. The specific findings of the 5 RT (17.6 kW) chiller are presented. Modeling incorporated a heat loss from the gas-fired generator and pressure drops in both the evaporator and absorber. Simulation results and experimental findings agreed closely and validated the modeling method and simulation software.

  20. Purge needs in absorption chillers

    SciTech Connect (OSTI)

    Murray, J.G. )

    1993-10-01

    Absorption chillers are regaining a significant share of large tonnage chiller sales, such as they had 20 years ago. Gas-fired chillers are now available that have a base energy (ultimate fuel usage) consumption rate per ton comparable to that in electric units. Effective purging in an absorption chiller is an absolute necessity to achieve the low chilled water temperature needed for dehumidification and to fully benefit from the energy savings offered by double-effect cycles. Although the purge system is usually not shown on the typical cycle schematic, its proper functioning is a key requirement for satisfactory machine operation. This article discusses the effect of noncondensible (N/C) gases on the absorption cooling process and the basics of purge systems. In addition, the article discusses the rationale for the important design step of selecting the location of the N/C probe, and discusses purge systems applicable to the direct-fired, double-effect machines now entering the marketplace.

  1. General Atomics (GA) | Princeton Plasma Physics Lab

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

    General Atomics (GA) Subscribe to RSS - General Atomics (GA) General Atomics Image: General Atomics (GA) The Scorpion's Strategy: "Catch and Subdue" Read more about The Scorpion's...

  2. The Harnessed Atom | Department of Energy

    Office of Environmental Management (EM)

    The Harnessed Atom The Harnessed Atom The Harnessed Atom The Harnessed Atom is a new middle school science, technology, engineering, and math (STEM) curriculum extension...

  3. Spectroscopy of triply and quadruply ionized states of mercury

    SciTech Connect (OSTI)

    Huttula, M.; Huttula, S.-M.; Lablanquie, P.; Palaudoux, J.; Penent, F.; Andric, L.; Eland, J. H. D.

    2011-03-15

    Multielectron coincidence spectroscopy has been used to study multiple ionization of atomic mercury. The binding energies of triply and quadruply ionized states of Hg have been determined from three- and fourfold electron coincidences. Relativistic ab initio theory has been used to calculate the state energies and predict the experimental findings.

  4. Absorption Cooling Basics | Department of Energy

    Broader source: Energy.gov (indexed) [DOE]

    Absorption coolers use heat rather than electricity as their energy source. Because natural gas is the most common heat source for absorption cooling, it is also referred to as...

  5. Low temperature atomic layer deposited ZnO photo thin film transistors

    SciTech Connect (OSTI)

    Oruc, Feyza B.; Aygun, Levent E.; Donmez, Inci; Biyikli, Necmi; Okyay, Ali K.; Yu, Hyun Yong

    2015-01-01

    ZnO thin film transistors (TFTs) are fabricated on Si substrates using atomic layer deposition technique. The growth temperature of ZnO channel layers are selected as 80, 100, 120, 130, and 250?C. Material characteristics of ZnO films are examined using x-ray photoelectron spectroscopy and x-ray diffraction methods. Stoichiometry analyses showed that the amount of both oxygen vacancies and interstitial zinc decrease with decreasing growth temperature. Electrical characteristics improve with decreasing growth temperature. Best results are obtained with ZnO channels deposited at 80?C; I{sub on}/I{sub off} ratio is extracted as 7.8 10{sup 9} and subthreshold slope is extracted as 0.116 V/dec. Flexible ZnO TFT devices are also fabricated using films grown at 80?C. I{sub D}V{sub GS} characterization results showed that devices fabricated on different substrates (Si and polyethylene terephthalate) show similar electrical characteristics. Sub-bandgap photo sensing properties of ZnO based TFTs are investigated; it is shown that visible light absorption of ZnO based TFTs can be actively controlled by external gate bias.

  6. NREL: Measurements and Characterization - Reflectance Spectroscopy

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

    ... Photoluminescence Spectroscopy Minority-Carrier Lifetime Spectroscopy Fourier-Transform Infrared & Raman Spectroscopy Spectroscopic Ellipsometry Capacitance Techniques Scanning ...

  7. The Local Atomic Structure and Chemical Bonding in Sodium Tin Phases

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

    Baggetto, Loic; Bridges, Craig A.; Jumas, Dr. Jean-Claude; Mullins, David R.; Carroll, Kyler J.; Meisner, Roberta; Crumlin, Ethan; Liu, Xiason; Yang, Wanli; Veith, Gabriel M.

    2014-09-25

    To understand these electrochemically-derived materials we have reinvestigated the formation of Na-Sn alloys to identify all the phases which form when x ≥ 1 (NaxSn) and characterized the local bonding around the Sn atoms with X-ray diffraction, 119Sn M ssbauer spectroscopy, and X-ray absorption spectroscopies. The results from the well-defined crystallographic materials were compared to the spectroscopic measurements of the local Sn structures in the electrochemically prepared materials. The reinvestigation of the Na-Sn compounds yields a number of new results: (i) Na7Sn3 is a new thermodynamically-stable phase with a rhombohedral structure and R-3m space group; (ii) orthorhombic Na9Sn4 (Cmcm) hasmore » relatively slow formation kinetics suggesting why it does not form at room temperature during the electrochemical reaction; (iii) orthorhombic Na14.78Sn4 (Pnma), better described as Na16-xSn4, is Na-richer than cubic Na15Sn4 (I-43d). Characterization of electrochemically prepared Na-Sn alloys indicate that, at the exception of Na7Sn3 and Na15Sn4, different crystal structures than similar Na-Sn compositions prepared via classic solid state reactions are formed. These phases are composed of disordered structures characteristic of kinetic-driven solid-state amorphization reactions. In these structures, Sn coordinates in asymmetric environments, which differ significantly from the environments present in Na-Sn model compounds.« less

  8. Atomic vapor laser isotope separation

    SciTech Connect (OSTI)

    Stern, R.C.; Paisner, J.A.

    1986-08-15

    The atomic vapor laser isotope separation (AVLIS) process for the enrichment of uranium is evaluated. (AIP)

  9. Regional respiratory tract absorption of inhaled reactive gases

    SciTech Connect (OSTI)

    Miller, F.J.; Overton, J.H.; Kimbell, J.S.; Russell, M.L.

    1992-06-29

    Highly reactive gases present unique problems due to the number of factors which must be taken into account to determine regional respiratory tract uptake. The authors reviewed some of the physical, chemical, and biological factors that affect dose and that must be understood to interpret toxicological data, to evaluate experimental dosimetry studies, and to develop dosimetry models. Selected dosimetry experiments involving laboratory animals and humans were discussed, showing the variability and uptake according to animal species and respiratory tract region for various reactive gases. New experimental dosimetry approaches, such as those involving isotope ratio mass spectroscopy and cyclotron generation reactive gases, were discussed that offer great promise for improving the ability to study regional respiratory tract absorption of reactive gases. Various dosimetry modeling applications were discussed which demonstrate: the importance of airflow patterns for site-specific dosimetry in the upper respiratory tract, the influence of the anatomical model used to make inter- and intraspecies dosimetric comparisons, the influence of tracheobronchial path length on predicted dose curves, and the implications of ventilatory unit structure and volume on dosimetry and response. Collectively, these examples illustrate important aspects of regional respiratory tract absorption of inhaled reactive gases. Given the complex nature of extent and pattern of injury in the respiratory tract from exposure to reactive gases, understanding interspecies differences in the absorption of reactive gases will continue to be an important area for study.

  10. Effects of thermal motion on electromagnetically induced absorption

    SciTech Connect (OSTI)

    Tilchin, E.; Wilson-Gordon, A. D.; Firstenberg, O.

    2011-05-15

    We describe the effect of thermal motion and buffer-gas collisions on a four-level closed N system interacting with strong pump(s) and a weak probe. This is the simplest system that experiences electromagnetically induced absorption (EIA) due to transfer of coherence via spontaneous emission from the excited state to the ground state. We investigate the influence of Doppler broadening, velocity-changing collisions (VCC), and phase-changing collisions (PCC) with a buffer gas on the EIA spectrum of optically active atoms. In addition to exact expressions, we present an approximate solution for the probe absorption spectrum, which provides physical insight into the behavior of the EIA peak due to VCC, PCC, and the wave-vector difference between the pump and probe beams. VCC are shown to produce a wide pedestal at the base of the EIA peak, which is scarcely affected by the pump-probe angular deviation, whereas the sharp central EIA peak becomes weaker and broader due to the residual Doppler-Dicke effect. Using diffusionlike equations for the atomic coherences and populations, we construct a spatial-frequency filter for a spatially structured probe beam and show that Ramsey narrowing of the EIA peak is obtained for beams of finite width.

  11. Iowa Powder Atomization Technologies

    SciTech Connect (OSTI)

    2012-01-01

    The same atomization effect seen in a fuel injector is being applied to titanium metal resulting in fine titanium powders that are less than half the width of a human hair. Titanium melts above 3,000°F and is highly corrosive therefore requiring specialized containers. The liquid titanium is poured through an Ames Laboratory - USDOE patented tube which is intended to increase the energy efficiency of the atomization process, which has the ability to dramatically decrease the cost of fine titanium powders. This novel process could open markets for green manufacturing of titanium components from jet engines to biomedical implants.

  12. Atomic Force Microscope

    SciTech Connect (OSTI)

    Day, R.D.; Russell, P.E.

    1988-12-01

    The Atomic Force Microscope (AFM) is a recently developed instrument that has achieved atomic resolution imaging of both conducting and non- conducting surfaces. Because the AFM is in the early stages of development, and because of the difficulty of building the instrument, it is currently in use in fewer than ten laboratories worldwide. It promises to be a valuable tool for obtaining information about engineering surfaces and aiding the .study of precision fabrication processes. This paper gives an overview of AFM technology and presents plans to build an instrument designed to look at engineering surfaces.

  13. Iowa Powder Atomization Technologies

    ScienceCinema (OSTI)

    None

    2013-03-01

    The same atomization effect seen in a fuel injector is being applied to titanium metal resulting in fine titanium powders that are less than half the width of a human hair. Titanium melts above 3,000°F and is highly corrosive therefore requiring specialized containers. The liquid titanium is poured through an Ames Laboratory - USDOE patented tube which is intended to increase the energy efficiency of the atomization process, which has the ability to dramatically decrease the cost of fine titanium powders. This novel process could open markets for green manufacturing of titanium components from jet engines to biomedical implants.

  14. Advanced regenerative absorption refrigeration cycles

    DOE Patents [OSTI]

    Dao, Kim

    1990-01-01

    Multi-effect regenerative absorption cycles which provide a high coefficient of performance (COP) at relatively high input temperatures. An absorber-coupled double-effect regenerative cycle (ADR cycle) (10) is provided having a single-effect absorption cycle (SEA cycle) (11) as a topping subcycle and a single-effect regenerative absorption cycle (1R cycle) (12) as a bottoming subcycle. The SEA cycle (11) includes a boiler (13), a condenser (21), an expansion device (28), an evaporator (31), and an absorber (40), all operatively connected together. The 1R cycle (12) includes a multistage boiler (48), a multi-stage resorber (51), a multisection regenerator (49) and also uses the condenser (21), expansion device (28) and evaporator (31) of the SEA topping subcycle (11), all operatively connected together. External heat is applied to the SEA boiler (13) for operation up to about 500 degrees F., with most of the high pressure vapor going to the condenser (21) and evaporator (31) being generated by the regenerator (49). The substantially adiabatic and isothermal functioning of the SER subcycle (12) provides a high COP. For higher input temperatures of up to 700 degrees F., another SEA cycle (111) is used as a topping subcycle, with the absorber (140) of the topping subcycle being heat coupled to the boiler (13) of an ADR cycle (10). The 1R cycle (12) itself is an improvement in that all resorber stages (50b-f) have a portion of their output pumped to boiling conduits (71a-f) through the regenerator (49), which conduits are connected to and at the same pressure as the highest pressure stage (48a) of the 1R multistage boiler (48).

  15. Alternation of the Pd Lattice in Nano-Sized-Pd/ZrO2 Composite during Hydrogen Absorption

    SciTech Connect (OSTI)

    Arachi, Yoshinori; Asai, Takeshi; Emura, Shuichi; Omura, Akira; Nunogaki, Masanobu; Yamaura, Shunichi; Inoue, Akihisa; Arata, Yoshiaki

    2007-02-02

    Structural analysis of high Deuterium absorbed 5 nm Pd particles in dispersed ZrO2 has been carried out using XAFS techniques. X-ray absorption spectra around the Pd K-absorption edge were observed and analyzed. The Pd-Pd bonding distance in the fcc Pd lattice was enlarged by 0.08 {approx} 0.09 A during absorption of deuterium, and it completely reverted to its original state with the release of deuterium while maintaining the crystal lattice symmetry. These changes provide evidence that deuterium locates not on the surface of the Pd particle, but rather within the Pd crystal lattice. XANES spectra clearly indicate that any change in the oxidation state of Pd are not observed, resulting in no reaction of the absorbed Deuterium atoms with Pd atoms. This paper reports the alternation of Pd lattice in nano-sized composite during hydrogen absorption. The possible models of deuterium position in the Pd lattice are also discussed.

  16. NEUTRON ABSORPTION AND SHIELDING DEVICE

    DOE Patents [OSTI]

    Axelrad, I.R.

    1960-06-21

    A neutron absorption and shielding device is described which is adapted for mounting in a radiation shielding wall surrounding a radioactive area through which instrumentation leads and the like may safely pass without permitting gamma or neutron radiation to pass to the exterior. The shielding device comprises a container having at least one nonrectilinear tube or passageway means extending therethrough, which is adapted to contain instrumentation leads or the like, a layer of a substance capable of absorbing gamma rays, and a solid resinous composition adapted to attenuate fast-moving neutrons and capture slow- moving or thermal neutrons.

  17. FC-PAD Organization and Activities

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

    ... electron microscopy (STEM) Atomic resolution imaging Electron Energy ... using electrochemical techniques X-ray absorption spectroscopy for catalyst ...

  18. Photoemission Spectroscopy at SRI2013

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

    Photoemission Spectroscopy at SRI2013 Workshop on Photoemission Spectroscopy: The Upcoming Decades Organizers: Alexei Fedorov (ALS) and Peter Johnson (BNL) Tuesday, June 18, 2013 *...

  19. A cryogenic circulating advective multi-pass absorption cell

    SciTech Connect (OSTI)

    Stockett, M. H.; Lawler, J. E. [Department of Physics, University of Wisconsin, 1150 University Avenue, Madison, Wisconsin 53706 (United States)

    2012-03-15

    A novel absorption cell has been developed to enable a spectroscopic survey of a broad range of polycyclic aromatic hydrocarbons (PAH) under astrophysically relevant conditions and utilizing a synchrotron radiation continuum to test the still controversial hypothesis that these molecules or their ions could be carriers of the diffuse interstellar bands. The cryogenic circulating advective multi-pass absorption cell resembles a wind tunnel; molecules evaporated from a crucible or injected using a custom gas feedthrough are entrained in a laminar flow of cryogenically cooled buffer gas and advected into the path of the synchrotron beam. This system includes a multi-pass optical White cell enabling absorption path lengths of hundreds of meters and a detection sensitivity to molecular densities on the order of 10{sup 7} cm{sup -3}. A capacitively coupled radio frequency dielectric barrier discharge provides ionized and metastable buffer gas atoms for ionizing the candidate molecules via charge exchange and the Penning effect. Stronger than expected clustering of PAH molecules has slowed efforts to record gas phase PAH spectra at cryogenic temperatures, though such clusters may play a role in other interstellar phenomena.

  20. Nonlinear Laser Spectroscopy

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

    ... Nonlinear optical techniques investigated in this program include time-resolved coherent anti-Stokes Raman spectroscopy, degenerate four-wave mixing, coherent 1D and 2D imaging ...

  1. INL Laboratory Scale Atomizer

    SciTech Connect (OSTI)

    C.R. Clark; G.C. Knighton; R.S. Fielding; N.P. Hallinan

    2010-01-01

    A laboratory scale atomizer has been built at the Idaho National Laboratory. This has proven useful for laboratory scale tests and has been used to fabricate fuel used in the RERTR miniplate experiments. This instrument evolved over time with various improvements being made ‘on the fly’ in a trial and error process.

  2. Polarized micro Raman scattering spectroscopy for curved edges of epitaxial graphene

    SciTech Connect (OSTI)

    Islam, Md. Sherajul Makino, T.; Hashimoto, A.; Bhuiyan, A. G.; Tanaka, S.

    2014-12-15

    This letter performed polarized microscopic laser Raman scattering spectroscopy on the curved edges of transferred epitaxial graphene on SiO{sub 2}/Si. The intensity ratio between the parallel and perpendicular polarized D band is evolved, providing a spectroscopy-based technique to probe the atomic-scale edge structures in graphene. A detailed analysis procedure for non-ideal disordered curved edges of graphene is developed combining the atomic-scale zigzag and armchair edge structures along with some point defects. These results could provide valuable information of the realistic edges of graphene at the atomic-scale that can strongly influence the performance of graphene-based nanodevices.

  3. Raman-Ramsey multizone spectroscopy in a pure rubidium vapor cell

    SciTech Connect (OSTI)

    Failache, H.; Lenci, L.; Lezama, A. [Instituto de Fisica, Facultad de Ingenieria, Universidad de la Republica, 11300 Montevideo (Uruguay)

    2010-02-15

    In view of application to a miniaturized spectroscopy system, we consider an optical setup that splits a laser beam into several parallel narrow light sheets allowing an effective beam expansion and consequently longer atom-light interaction times. We analyze the multizone coherent population trapping (MZCPT) spectroscopy of alkali-metal-vapor atoms, without buffer gas, in the presence of a split light beam. We show that the MZCPT signal is largely insensitive to intensity broadening. Experimentally observed spectra are in qualitative agreement with the predictions of a simplified model that describes each spectrum as an integral over the atomic velocity distribution of Ramsey multizone spectra.

  4. Ultracold Atoms: How Quantum Field Theory Invaded Atomic Physics

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

    Ultracold Atoms: How Quantum Field Theory Invaded Atomic Physics Eric Braaten Ohio State University May 6, 2015 4:00 p.m. (coffee @ 3:30) The development of the technology for trapping atoms and cooling them to ultralow temperatures gave birth to a new subfield of atomic physics. It also led to the introduction of new theoretical methods into atomic physics, I n particular quantum field theory (QFT). Methods of QFT developed in high energy physics have proved to be very useful in ultracold atom

  5. Design of Molecular Solar Cells via Feedback from Soft X-ray Spectroscopy

    SciTech Connect (OSTI)

    Himpsel, Franz J.

    2015-06-12

    Spectroscopy with soft X-rays was used to develop new materials and novel designs for solar cells and artificial photosynthesis. In order to go beyond the widely-used trial-and-error approach of gradually improving a particular design, we started from the most general layout of a solar cell (or a photo-electrochemical device) and asked which classes of materials are promising for best performance. For example, the most general design of a solar cell consists of a light absorber, an electron donor, and an electron acceptor. These are characterized by four energy levels, which were measured by a combination of spectroscopic X-ray techniques. Tuning synchrotron radiation to the absorption edges of specific elements provided element- and bond-selectivity. The spectroscopic results were complemented by state-of-the-art calculations of the electronic states. These helped explaining the observed energy levels and the orbitals associated with them. The calculations were extended to a large class of materials (for example thousands of porphyrin dye complexes) in order to survey trends in the energy level structure. A few highlights serve as examples: 1) Organic molecules combining absorber, donor, and acceptor with atomic precision. 2) Exploration of highly p-doped diamond films as inert, transparent electron donors. 3) Surface-sensitive characterization of nanorod arrays used as photoanodes in water splitting. 4) Computational design of molecular complexes for efficient solar cells using two photons.

  6. Olefin recovery via chemical absorption

    SciTech Connect (OSTI)

    Barchas, R.

    1998-06-01

    The recovery of fight olefins in petrochemical plants has generally been accomplished through cryogenic distillation, a process which is very capital and energy intensive. In an effort to simplify the recovery process and reduce its cost, BP Chemicals has developed a chemical absorption technology based on an aqueous silver nitrate solution. Stone & Webster is now marketing, licensing, and engineering the technology. The process is commercially ready for recovering olefins from olefin derivative plant vent gases, such as vents from polyethylene, polypropylene, ethylene oxide, and synthetic ethanol units. The process can also be used to debottleneck C{sub 2} or C{sub 3} splinters, or to improve olefin product purity. This paper presents the olefin recovery imp technology, discusses its applications, and presents economics for the recovery of ethylene and propylene.

  7. Backscatter absorption gas imaging system

    DOE Patents [OSTI]

    McRae, T.G. Jr.

    A video imaging system for detecting hazardous gas leaks. Visual displays of invisible gas clouds are produced by radiation augmentation of the field of view of an imaging device by radiation corresponding to an absorption line of the gas to be detected. The field of view of an imager is irradiated by a laser. The imager receives both backscattered laser light and background radiation. When a detectable gas is present, the backscattered laser light is highly attenuated, producing a region of contrast or shadow on the image. A flying spot imaging system is utilized to synchronously irradiate and scan the area to lower laser power requirements. The imager signal is processed to produce a video display.

  8. Backscatter absorption gas imaging system

    DOE Patents [OSTI]

    McRae, Jr., Thomas G.

    1985-01-01

    A video imaging system for detecting hazardous gas leaks. Visual displays of invisible gas clouds are produced by radiation augmentation of the field of view of an imaging device by radiation corresponding to an absorption line of the gas to be detected. The field of view of an imager is irradiated by a laser. The imager receives both backscattered laser light and background radiation. When a detectable gas is present, the backscattered laser light is highly attenuated, producing a region of contrast or shadow on the image. A flying spot imaging system is utilized to synchronously irradiate and scan the area to lower laser power requirements. The imager signal is processed to produce a video display.

  9. Neutron scattering and absorption properties

    SciTech Connect (OSTI)

    Holden, N.E.

    1993-12-01

    The Table in this report presents an evaluated set of values for the experimental quantities, which characterize the properties for scattering and absorption of neutrons. The neutron cross section is given for room temperature neutrons, 20.43{degree}C, corresponds to a thermal neutron energy of 0.0253 electron volts (eV) or a neutron velocity of 2200 meters/second. The neutron resonance integral is defined over the energy range from 0.5 eV to 0.1 {times} 10{sup 6} eV, or 0.1 MeV. A list of the major references used is given below. The literature cutoff data is October 1993. Uncertainties are given in parentheses. Parentheses with two or more numbers indicate values to the excited states(s) and to the ground state of the product nucleus.

  10. Lawrenciums ionization potential, atom by atom

    SciTech Connect (OSTI)

    Miller, Johanna L.

    2015-06-15

    Researchers in Japan have begun probing the atomic physics of elements that can be produced only in minute quantities.

  11. A microfabricated atomic clock

    SciTech Connect (OSTI)

    Knappe, Svenja; Shah, Vishal; Schwindt, Peter D.D.; Hollberg, Leo; Kitching, John; Liew, Li-Anne; Moreland, John

    2004-08-30

    Fabrication techniques usually applied to microelectromechanical systems (MEMS) are used to reduce the size and operating power of the core physics assembly of an atomic clock. With a volume of 9.5 mm{sup 3}, a fractional frequency instability of 2.5x10{sup -10} at 1 s of integration, and dissipating less than 75 mW of power, the device has the potential to bring atomically precise timing to hand-held, battery-operated devices. In addition, the design and fabrication process allows for wafer-level assembly of the structures, enabling low-cost mass-production of thousands of identical units with the same process sequence, and easy integration with other electronics.

  12. ATOMIC ENERGY COMMISSION

    Office of Legacy Management (LM)

    ' ATOMIC ENERGY COMMISSION Frank K. Pittman, Director, bivisioa of Waste &&gement and s- portation, Headquarters j CONTAMItUTED RX-AEC-OWNED OR LEASED FACILITIES' This memorandum responds to your TWX certain information on the above subject. the documentation necessary to answer your available due to the records disposal vailing at the time of release or From records that are available and from disc&ions with most familiar with the transfer operations, &have the current

  13. Isotope Enrichment Detection by Laser Ablation - Laser Absorption Spectrometry: Automated Environmental Sampling and Laser-Based Analysis for HEU Detection

    SciTech Connect (OSTI)

    Anheier, Norman C.; Bushaw, Bruce A.

    2010-01-01

    The global expansion of nuclear power, and consequently the uranium enrichment industry, requires the development of new safeguards technology to mitigate proliferation risks. Current enrichment monitoring instruments exist that provide only yes/no detection of highly enriched uranium (HEU) production. More accurate accountancy measurements are typically restricted to gamma-ray and weight measurements taken in cylinder storage yards. Analysis of environmental and cylinder content samples have much higher effectiveness, but this approach requires onsite sampling, shipping, and time-consuming laboratory analysis and reporting. Given that large modern gaseous centrifuge enrichment plants (GCEPs) can quickly produce a significant quantity (SQ ) of HEU, these limitations in verification suggest the need for more timely detection of potential facility misuse. The Pacific Northwest National Laboratory (PNNL) is developing an unattended safeguards instrument concept, combining continuous aerosol particulate collection with uranium isotope assay, to provide timely analysis of enrichment levels within low enriched uranium facilities. This approach is based on laser vaporization of aerosol particulate samples, followed by wavelength tuned laser diode spectroscopy to characterize the uranium isotopic ratio through subtle differences in atomic absorption wavelengths. Environmental sampling (ES) media from an integrated aerosol collector is introduced into a small, reduced pressure chamber, where a focused pulsed laser vaporizes material from a 10 to 20-m diameter spot of the surface of the sampling media. The plume of ejected material begins as high-temperature plasma that yields ions and atoms, as well as molecules and molecular ions. We concentrate on the plume of atomic vapor that remains after the plasma has expanded and then cooled by the surrounding cover gas. Tunable diode lasers are directed through this plume and each isotope is detected by monitoring absorbance

  14. Advanced Low Temperature Absorption Chiller Module Integrated...

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

    Data Center - Presentation by Exergy Partners Corp., June 2011 Advanced Low Temperature Absorption Chiller Module Integrated with a CHP System at a Distributed Data Center - ...

  15. Absorption Heat Pump Basics | Department of Energy

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

    Heat Pump Basics Absorption Heat Pump Basics August 19, 2013 - 11:11am Addthis Absorption heat pumps are essentially air-source heat pumps driven not by electricity, but by a heat source such as natural gas, propane, solar-heated water, or geothermal-heated water. Because natural gas is the most common heat source for absorption heat pumps, they are also referred to as gas-fired heat pumps. There are also absorption coolers available that work on the same principal, but are not reversible and

  16. Compact Absorption Chiller - Energy Innovation Portal

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

    Energy Efficiency Building Energy Efficiency Find More Like This Return to Search Compact Absorption Chiller Pacific Northwest National Laboratory Contact PNNL About This...

  17. Commercial Absorption Heat Pump Water Heater

    Broader source: Energy.gov (indexed) [DOE]

    Absorption Heat Pump Water Heater 2016 Building Technologies Office Peer Review Patrick ... The target market is the hospital, hotel and full service restaurant gas hot water heating ...

  18. Pressure dependence of Hexanitrostilbene Raman/ electronic absorption...

    Office of Scientific and Technical Information (OSTI)

    Hexanitrostilbene Raman electronic absorption spectra to validate DFT EOS. Citation Details In-Document Search Title: Pressure dependence of Hexanitrostilbene Raman electronic ...

  19. Pressure dependence of Hexanitrostilbene Raman/ electronic absorption...

    Office of Scientific and Technical Information (OSTI)

    in hydrodynamic simulations of the performance of HNS, we have measured the Raman and electronic absorption spectra of this material under static pressure in a diamond anvil cell. ...

  20. Budget Atomization | Department of Energy

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

    Budget Atomization Budget Atomization Howard Dickenson, Deputy Associate Administrator for Acquisition and Project Management presented on Budget Atomization from the NNSA perspective. Howard presented an overview of the NNSA budget structure and an example of LANL controls. Chris Johns, Director of the Budget Office, DOE Office of the CFO presented on Budget Atomization from the DOE perspective. Chris provided an overview of funding, provided examples, and demonstrated the effect on labs/sites.

  1. Search for: All records | SciTech Connect

    Office of Scientific and Technical Information (OSTI)

    ... iron (3) oxygen (3) scattering (3) absorption spectroscopy (2) atoms ... particle size (2) particles (2) spectroscopy (2) ... consequences of small particle size in nanomaterials. ...

  2. Atomizer with liquid spray quenching

    DOE Patents [OSTI]

    Anderson, I.E.; Osborne, M.G.; Terpstra, R.L.

    1998-04-14

    Method and apparatus are disclosed for making metallic powder particles wherein a metallic melt is atomized by a rotating disk or other atomizer at an atomizing location in a manner to form molten droplets moving in a direction away from said atomizing location. The atomized droplets pass through a series of thin liquid quenching sheets disposed in succession about the atomizing location with each successive quenching sheet being at an increasing distance from the atomizing location. The atomized droplets are incrementally cooled and optionally passivated as they pass through the series of liquid quenching sheets without distorting the atomized droplets from their generally spherical shape. The atomized, cooled droplets can be received in a chamber having a collection wall disposed outwardly of the series of liquid quenching sheets. A liquid quenchant can be flowed proximate the chamber wall to carry the cooled atomized droplets to a collection chamber where atomized powder particles and the liquid quenchant are separated such that the liquid quenchant can be recycled. 6 figs.

  3. Atomizer with liquid spray quenching

    DOE Patents [OSTI]

    Anderson, Iver E.; Osborne, Matthew G.; Terpstra, Robert L.

    1998-04-14

    Method and apparatus for making metallic powder particles wherein a metallic melt is atomized by a rotating disk or other atomizer at an atomizing location in a manner to form molten droplets moving in a direction away from said atomizing location. The atomized droplets pass through a series of thin liquid quenching sheets disposed in succession about the atomizing location with each successive quenching sheet being at an increasing distance from the atomizing location. The atomized droplets are incrementally cooled and optionally passivated as they pass through the series of liquid quenching sheets without distorting the atomized droplets from their generally spherical shape. The atomized, cooled droplets can be received in a chamber having a collection wall disposed outwardly of the series of liquid quenching sheets. A liquid quenchant can be flowed proximate the chamber wall to carry the cooled atomized droplets to a collection chamber where atomized powder particles and the liquid quenchant are separated such that the liquid quenchant can be recycled.

  4. PROTON RESONANCE SPECTROSCOPY

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

    as a i i . : lJIiaSJ :ShUiI,,:;II. Iii II; PROTON RESONANCE SPECTROSCOPY IN 29p LAWRENCE H. JAMES Triangle Universities Nuclear Laboratory Department of Physics North Carolina State University 1989 - - .. - .. - .. Abstract James, Lawrence Hoy Proton Resonance Spectroscopy in 29 p (Under the direc- tion of Gary E. Mitchell) Proton elastic scattering on 28Si was measured with good beam energy resolution in the proton energy range Ep=1.4 to E =3.75 MeV, and proton inelastic scattering on p 28Si

  5. Transient simulation of absorption machines

    SciTech Connect (OSTI)

    Anand, D.K.; Allen, R.W.; Kumar, B.

    1982-08-01

    This paper presents a model for a water-cooled Lithium-Bromide/water absorption chiller and predicts its transient response both during the start-up phase and during the shutoff period. The simulation model incorporates such influencing factors as the thermodynamic properties of the working fluid, the absorbent, the heat-transfer configuration of different components of the chiller and related physical data. The time constants of different components are controlled by a set of key parameters that have been identified in this study. The results show a variable but at times significant amount of time delay before the chiller capacity gets close to its steady-state value. The model is intended to provide an insight into the mechanism of build-up to steady-state performance. By recognizing the significant factors contributing to transient degradation, steps can be taken to reduce such degradation. The evaluation of the residual capacity in the shut-off period will yield more realistic estimates of chiller COP for a chiller satisfying dynamic space cooling load.

  6. Transient simulation of absorption machines

    SciTech Connect (OSTI)

    Anand, D.K.; Allen, R.W.; Kumar, B.

    1982-08-01

    This paper presents a model for a water-cooled Lithium-Bromide/water absorption chiller and predicts its transient response both during the start-up phase and during the shutoff period. The simulation model incorporates such influencing factors as the thermodynamic properties of the working fluid, the absorbent, the heat-transfer configuration of different components of the chiller and related physical data. The time constants of different components are controlled by a set of key parameters that have been identified in this study. The results show a variable but at times significant amount of time delay before the chiller capacity gets close to its steadystate value. The model is intended to provide an insight into the mechanism of build-up to steady-state performance. By recognizing the significant factors contributing to transient degradation, steps can be taken to reduce such degradation. The evaluation of the residual capacity in the shut-off period will yield more realistic estimates of chiller COP for a chiller satisfying dynamic space cooling load.

  7. DOE - NNSA/NFO -- Atomic Testing Museum

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

    National Atomic Testing Museum NNSANFO Language Options U.S. DOENNSA - Nevada Field Office NATIONAL ATOMIC TESTING MUSEUM Photograph of Atomic Testing Museum The Nevada Test Site ...

  8. Atomic data for fusion

    SciTech Connect (OSTI)

    Hunter, H.T.; Kirkpatrick, M.I.; Alvarez, I.; Cisneros, C.; Phaneuf, R.A.; Barnett, C.F.

    1990-07-01

    This report provides a handbook of recommended cross-section and rate-coefficient data for inelastic collisions between hydrogen, helium and lithium atoms, molecules and ions, and encompasses more than 400 different reactions of primary interest in fusion research. Published experimental and theoretical data have been collected and evaluated, and the recommended data are presented in tabular, graphical and parametrized form. Processes include excitation and spectral line emission, charge exchange, ionization, stripping, dissociation and particle interchange reactions. The range of collision energies is appropriate to applications in fusion-energy research.

  9. Photoionization Mass Spectroscopy

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

    Photoionization Mass Spectroscopy - Sandia Energy Energy Search Icon Sandia Home Locations Contact Us Employee Locator Energy & Climate Secure & Sustainable Energy Future Stationary Power Energy Conversion Efficiency Solar Energy Wind Energy Water Power Supercritical CO2 Geothermal Natural Gas Safety, Security & Resilience of the Energy Infrastructure Energy Storage Nuclear Power & Engineering Grid Modernization Battery Testing Nuclear Energy Defense Waste Management Programs

  10. Atomically resolved force microscopy at room temperature

    SciTech Connect (OSTI)

    Morita, Seizo

    2014-04-24

    Atomic force microscopy (AFM) can now not only image individual atoms but also construct atom letters using atom manipulation method even at room temperature (RT). Therefore, the AFM is the second generation atomic tool following the scanning tunneling microscopy (STM). However the AFM can image even insulating atoms, and also directly measure/map the atomic force and potential at the atomic scale. Noting these advantages, we have been developing a bottom-up nanostructuring system at RT based on the AFM. It can identify chemical species of individual atoms and then manipulate selected atom species to the predesigned site one-by-one to assemble complex nanostructures consisted of multi atom species at RT. Here we introduce our results toward atom-by-atom assembly of composite nanostructures based on the AFM at RT including the latest result on atom gating of nano-space for atom-by-atom creation of atom clusters at RT for semiconductor surfaces.

  11. Gas-fueled absorption heat pump

    SciTech Connect (OSTI)

    Florette, M.; Peuportier, B.

    1982-01-01

    To determine the feasibility of using an absorption heat pump for residential space heating, French investigators are studying both theoretically and experimentally, the performance of the absorption cycle in terms of its efficiency and suitability to space-heating conditions. A 10-kW pilot unit is supplying data on design criteria, heat-exchange fluid selection, and heat and mass balances.

  12. New directions in optical atomic spectrometry

    SciTech Connect (OSTI)

    de Galan, L.

    1986-05-01

    Soon after its invention a successful method of analysis goes through a phase of rapid growth and exaggerated expectations before it recedes to a more balanced position in the analytical domain. Flame and furnace atomic absorption spectrometry (AAS) and inductively coupled plasma-atomic emission spectrometry (ICP-AES), as we know them now, were introduced 20 to 30 years ago, developed into commercial instruments within a decade after their first description in the scientific literature, and have now reached a state of developmental equilibrium. It is undeniable that these techniques have continued to develop, but recent advances have been largely technical and cosmetic. The emphasis on automation and software has made life much easier and has significantly reduced the demand for manpower, but it has not enlarged the analytical scope of the techniques. Many initial promises have been fulfilled, but some shortcomings persist even today. At this point it would be easy to formulate the ideal method that determines all elements from the sub-parts-per-billion level to the 100% level, simultaneously, with high precision and accuracy, and at minimal cost. Clearly, no single method can possibly match such unrealistic expectations. In this article the author has, therefore, chosen the more modest approach of identifying some weak points in available technology and analyzing possible remedies. In several cases current developments are reviewed, and novel instruments proposed in the literature are evaluated. In other cases, the problems have hardly been addressed and thus may pose a challenge for future research. 10 references, 6 tables.

  13. The Common Elements of Atomic and Hadronic Physics

    SciTech Connect (OSTI)

    Brodsky, Stanley J.

    2015-02-26

    Atomic physics and hadronic physics are both governed by the Yang Mills gauge theory Lagrangian; in fact, Abelian quantum electrodynamics can be regarded as the zero-color limit of quantum chromodynamics. I review a number of areas where the techniques of atomic physics can provide important insight into hadronic eigenstates in QCD. For example, the Dirac-Coulomb equation, which predicts the spectroscopy and structure of hydrogenic atoms, has an analog in hadron physics in the form of frame-independent light-front relativistic equations of motion consistent with light-front holography which give a remarkable first approximation to the spectroscopy, dynamics, and structure of light hadrons. The production of antihydrogen in flight can provide important insight into the dynamics of hadron production in QCD at the amplitude level. The renormalization scale for the running coupling is unambiguously set in QED; an analogous procedure sets the renormalization scales in QCD, leading to scheme-independent scale-fixed predictions. Conversely, many techniques which have been developed for hadron physics, such as scaling laws, evolution equations, the quark-interchange process and light-front quantization have important applicants for atomic physics and photon science, especially in the relativistic domain.

  14. Thermodynamic Evaluation of Hydrogen Absorption by Niobium During SRF Fabrication

    SciTech Connect (OSTI)

    Ricker, R. E.; Myneni, G. R.

    2011-03-31

    The properties and performance of the ultra high purity Nb used to fabricate superconducting radio frequency (SRF) particle accelerator cavities have been found to vary with processing conditions. One hypothesis for these variations is that hydrogen, absorbed during processing, is responsible for this behavior. The key assumption behind this hypothesis is that niobium can absorb hydrogen from one or more of the processing environments. This paper reviews work examining the validity of this assumption. It was determined that Nb will spontaneously react with water producing adsorbed atomic hydrogen that is readily absorbed into the metal. The passivating oxide film normally prevents this reaction, but this film is frequently removed during processing and it is attacked by the fluoride ion used in the polishing solutions for SRF cavities. However, during electropolishing that cathodic reduction of hydrogen is transferred to the auxiliary electrode and this should suppress hydrogen absorption.

  15. Atomic and electronic structure of Ni-Nb metallic glasses

    SciTech Connect (OSTI)

    Yuan, C. C.; Yang, Y.-F. Xi, X. K.

    2013-12-07

    Solid state {sup 93}Nb nuclear magnetic resonance spectroscopy has been employed to investigate the atomic and electronic structures in Ni-Nb based metallic glass (MG) model system. {sup 93}Nb nuclear magnetic resonance (NMR) isotropic metallic shift of Ni{sub 60}Nb{sub 35}Sn{sub 5} has been found to be ∼100 ppm lower than that of Ni{sub 60}Nb{sub 35}Zr{sub 5} MG, which is correlated with their intrinsic fracture toughness. The evolution of {sup 93}Nb NMR isotropic metallic shifts upon alloying is clearly an electronic origin, as revealed by both local hyperfine fields analysis and first-principle computations. This preliminary result indicates that, in addition to geometrical considerations, atomic form factors should be taken into a description of atomic structures for better understanding the mechanical behaviors of MGs.

  16. Novel absorption detection techniques for capillary electrophoresis

    SciTech Connect (OSTI)

    Xue, Y.

    1994-07-27

    Capillary electrophoresis (CE) has emerged as one of the most versatile separation methods. However, efficient separation is not sufficient unless coupled to adequate detection. The narrow inner diameter (I.D.) of the capillary column raises a big challenge to detection methods. For UV-vis absorption detection, the concentration sensitivity is only at the {mu}M level. Most commercial CE instruments are equipped with incoherent UV-vis lamps. Low-brightness, instability and inefficient coupling of the light source with the capillary limit the further improvement of UV-vis absorption detection in CE. The goals of this research have been to show the utility of laser-based absorption detection. The approaches involve: on-column double-beam laser absorption detection and its application to the detection of small ions and proteins, and absorption detection with the bubble-shaped flow cell.

  17. Absorption of carbonyl sulfide in aqueous methyldiethanolamine

    SciTech Connect (OSTI)

    Al-Ghawas, H.A.; Ruiz-Ibanez, G.; Sandall, O.C. (Dept. of Chemical and Nuclear Engineering, Univ. of California, Santa Barbara, CA (US))

    1988-01-01

    The absorption of carbonyl sulfide in aqueous methyldiethanolamine (MDEA) was studied over a range of temperatures and MDEA concentrations. MDEA is commonly used for selective absorption of hydrogen sulfide in the presence of carbon dioxide. However, sulfur in the form of COS may also be present and it is necessary that estimates of absorption rates of this compound be made. The objective of this study is to determine the physiochemical properties needed to predict COS absorption rates in aqueous MDEA. Free gas solubility and the diffusivity of COS in MDEA solutions were measured over the temperature range 15 to 40{sup 0}C for MDEA concentrations up to 30 weight per cent using the nitrous oxide analogy method. Solubilities were measured volumetrically in an equilibrium cell and diffusivities were measured using a laminar liquid jet absorber. The kinetics of the reaction between COS and MDEA were studied by measuring absorption rates in a single wetted-sphere absorber.

  18. Q-Spectroscopy

    SciTech Connect (OSTI)

    Hoover, Andrew Scott

    2015-02-23

    A new tool for rapid single-particle analysis in safeguards is described. This quantitative analysis tool has advantages over conventional methods for isotopic analysis of actinide-bearing samples. The method can be used to determine chemical age via 241Am/241Pu ''atomic clock''.

  19. Finite temperature effects on the X-ray absorption spectra of lithium compounds: First-principles interpretation of X-ray Raman measurements

    SciTech Connect (OSTI)

    Pascal, Tod A.; Prendergast, David; Boesenberg, Ulrike; Kostecki, Robert; Richardson, Thomas J.; Weng, Tsu-Chien; Sokaras, Dimosthenis; Nordlund, Dennis; McDermott, Eamon; Moewes, Alexander; Cabana, Jordi

    2014-01-21

    We elucidate the role of room-temperature-induced instantaneous structural distortions in the Li K-edge X-ray absorption spectra (XAS) of crystalline LiF, Li{sub 2}SO{sub 4}, Li{sub 2}O, Li{sub 3}N, and Li{sub 2}CO{sub 3} using high resolution X-ray Raman spectroscopy (XRS) measurements and first-principles density functional theory calculations within the eXcited electron and Core Hole approach. Based on thermodynamic sampling via ab initio molecular dynamics simulations, we find calculated XAS in much better agreement with experiment than those computed using the rigid crystal structure alone. We show that local instantaneous distortion of the atomic lattice perturbs the symmetry of the Li 1s core-excited-state electronic structure, broadening spectral line-shapes and, in some cases, producing additional spectral features. The excellent agreement with high-resolution XRS measurements validates the accuracy of our first-principles approach to simulating XAS, and provides both accurate benchmarks for model compounds and a predictive theoretical capability for identification and characterization of multi-component systems, such as lithium-ion batteries, under working conditions.

  20. Influence of the pH value of a colloidal gold solution on the absorption spectra of an LSPR-assisted sensor

    SciTech Connect (OSTI)

    Zhu, Jin; Li, Wenbin; Zhu, Mao; Zhang, Wei; Niu, Wencheng; Liu, Guohua

    2014-03-15

    The localized surface plasmon resonances (LSPRs) of gold particles assembled on a crystal plate are a powerful tool for biological sensors. Here, we prepare gold colloids in different pH solutions. We monitor the effects of the particle radius and particle coverage on the absorption spectra of AT-cut (r-face dihedral angle of about 3°) crystal plates supporting gold nanoparticles. The surface morphologies were monitored on silicon dioxide substrates using ultraviolet and visible (UV-vis) spectroscopy, and atomic force microscopy (AFM). The results showed that the gold particle coverage decreases with increasing pH value of the gold colloid solution. This phenomenon demonstrates that self-assembled gold surfaces were formed via the electrostatic adsorption of gold particles on the positively charged, ionized amino groups on the crystal plates in the acidic solution. The spectrum of gold nanoparticles with different coverage degree on the crystal plates showed that the LSPR properties are highly dependent on pH.

  1. Enhanced Absorption in 2D Materials Via Fano- Resonant Photonic Crystals

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

    Wang, Wenyi; Klotz, Andrey; Yang, Yuanmu; Li, Wei; Kravchenko, Ivan I.; Briggs, Dayrl P.; Bolotin, Kirill; Valentine, Jason

    2015-05-01

    The use of two-dimensional (2D) materials in optoelectronics has attracted much attention due to their fascinating optical and electrical properties. For instance, graphenebased devices have been employed for applications such as ultrafast and broadband photodetectors and modulators while transition metal dichalcogenide (TMDC) based photodetectors can be used for ultrasensitive photodetection. However, the low optical absorption of 2D materials arising from their atomic thickness limits the maximum attainable external quantum efficiency. For example, in the visible and NIR regimes monolayer MoS2 and graphene absorb only ~10% and 2.3% of incoming light, respectively. Here, we experimentally demonstrate the use of Fano-resonant photonicmore » crystals to significantly boost absorption in atomically thin materials. Using graphene as a test bed, we demonstrate that absorption in the monolayer thick material can be enhanced to 77% within the telecommunications band, the highest value reported to date. We also show that the absorption in the Fano-resonant structure is non-local, with light propagating up to 16 μm within the structure. This property is particularly beneficial in harvesting light from large areas in field-effect-transistor based graphene photodetectors in which separation of photo-generated carriers only occurs ~0.2 μm adjacent to the graphene/electrode interface.« less

  2. Synthesis of Pt–Pd Core–Shell Nanostructures by Atomic Layer Deposition: Application in Propane Oxidative Dehydrogenation to Propylene

    SciTech Connect (OSTI)

    Lei, Yu; Liu, Bin; Lu, Junling; Lobo-Lapidus, Rodrigo J.; Wu, Tianpin; Feng, Hao; Xia, Xiaoxing; Mane, Anil U.; Libera, Joseph A.; Greeley, Jeffrey P.; Miller, Jeffrey T.; Elam, Jeffrey W.

    2012-08-20

    Atomic layer deposition (ALD) was employed to synthesize supported Pt–Pd bimetallic particles in the 1 to 2 nm range. The metal loading and composition of the supported Pt–Pd nanoparticles were controlled by varying the deposition temperature and by applying ALD metal oxide coatings to modify the support surface chemistry. High-resolution scanning transmission electron microscopy images showed monodispersed Pt–Pd nanoparticles on ALD Al2O3- and TiO2-modified SiO2 gel. X-ray absorption spectroscopy revealed that the bimetallic nanoparticles have a stable Pt-core, Pd-shell nanostructure. Density functional theory calculations revealed that the most stable surface configuration for the Pt–Pd alloys in an H2 environment has a Pt-core, Pd-shell nanostructure. Finally, in comparison to their monometallic counterparts, the small Pt–Pd bimetallic core–shell nanoparticles exhibited higher activity in propane oxidative dehydrogenation as compared to their physical mixture.

  3. Hydrogen Absorption in Pd-based Nanostructures - Final Report

    SciTech Connect (OSTI)

    David Lederman

    2012-10-22

    Pd is known to absorb hydrogen. Molecules are normally chemisorbed at the surface in a process where the molecule breaks into two hydrogen atoms, and the protons are then absorbed into the bulk. This process consists of electron filling holes in the Pd 4d band near the Fermi energy, which due to the high density of states at the Fermi energy, is an energetically favorable process. Our aim with this project was to determine possible changes in magnetic properties with Pd nm-length-scale thick layers intercalated by magnetic materials. Before the start of this work, the literature indicated that there were several possible scenarios by which this could happen: i) the Pd will be magnetized due to a proximity effect with nearby magnetic layers, resulting in changes in the magnetization due to H2 absorption; ii) some H will be absorbed into the magnetic layers, causing a change in the magnetic exchange interactions; or iii) absorption of H2 will cause an expansion of the lattice, resulting in a magnetoelastic effect which changes the magnetic properties.

  4. Dirac Charge Dynamcs in Graphene by Infrared Spectroscopy

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

  5. Dirac Charge Dynamcs in Graphene by Infrared Spectroscopy

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

  6. Dirac Charge Dynamcs in Graphene by Infrared Spectroscopy

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

  7. Dirac Charge Dynamcs in Graphene by Infrared Spectroscopy

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

  8. Dirac Charge Dynamcs in Graphene by Infrared Spectroscopy

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

  9. Dirac Charge Dynamcs in Graphene by Infrared Spectroscopy

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

  10. Dirac Charge Dynamcs in Graphene by Infrared Spectroscopy

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

  11. Absorption chillers: Technology for the future

    SciTech Connect (OSTI)

    Garland, P.W.; Garland, R.W.

    1997-12-31

    In an era of heightened awareness of energy efficiency and the associated environmental impacts, many industries worldwide are exploring ``environmentally friendly`` technologies that provide equivalent or improved performance while reducing or eliminating harmful side-effects. The refrigeration and air-conditioning industry, due to its reliance on CFCs and HCFCs, has invested in research in alternatives to the industry standard vapor compression machines. One alternative technology with great promise is chemical absorption. Absorption chillers offer comparable refrigeration output with reduced SO{sub 2}, CO{sub 2}, and NO{sub x} emissions. Absorption chillers do not use CFCs or HCFCs, refrigerants that contribute to ozone depletion and global warming. Additionally, gas-fired absorption chillers can save significant amounts in energy costs when used in combination with a vapor compression chiller in a hybrid system. The hybrid system can take advantage of the comparatively low price of natural gas (per unit ton) and rely on the high performance of vapor compression when electricity prices are lower. The purpose of this article is to provide an introduction for those new to absorption technology as well as a discussion of selected high efficiency cycles, a discussion on the technology of coupling absorption with vapor compression systems to form a hybrid system, and the environmental impacts of absorption.

  12. Nonlinear Laser Spectroscopy

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

    Laser Spectroscopy - Sandia Energy Energy Search Icon Sandia Home Locations Contact Us Employee Locator Energy & Climate Secure & Sustainable Energy Future Stationary Power Energy Conversion Efficiency Solar Energy Wind Energy Water Power Supercritical CO2 Geothermal Natural Gas Safety, Security & Resilience of the Energy Infrastructure Energy Storage Nuclear Power & Engineering Grid Modernization Battery Testing Nuclear Energy Defense Waste Management Programs Advanced Nuclear

  13. The Collective Atomic Recoil Laser

    SciTech Connect (OSTI)

    Courteille, Ph.W.; Cube, C. avon; Deh, B.; Kruse, D.; Ludewig, A.; Slama, S.; Zimmermann, C.

    2005-05-05

    An ensemble of periodically ordered atoms coherently scatters the light of an incident laser beam. The scattered and the incident light may interfere and give rise to a light intensity modulation and thus to optical dipole forces which, in turn, emphasize the atomic ordering. This positive feedback is at the origin of the collective atomic recoil laser (CARL). We demonstrate this dynamics using ultracold atoms confined by dipole forces in a unidirectionally pumped far red-detuned high-finesse optical ring cavity. Under the influence of an additional dissipative force exerted by an optical molasses the atoms, starting from an unordered distribution, spontaneously form a density grating moving at constant velocity. Additionally, steady state lasing is observed in the reverse direction if the pump laser power exceeds a certain threshold. We compare the dynamics of the atomic trajectories to the behavior of globally coupled oscillators, which exhibit phase transitions from incoherent to coherent states if the coupling strength exceeds a critical value.

  14. Effects of rapid thermal annealing on the structural and local atomic properties of ZnO: Ge nanocomposite thin films

    SciTech Connect (OSTI)

    Ceylan, Abdullah Ozcan, Sadan; Rumaiz, Abdul K.; Caliskan, Deniz; Ozbay, Ekmel; Woicik, J. C.

    2015-03-14

    We have investigated the structural and local atomic properties of Ge nanocrystals (Ge-ncs) embedded ZnO (ZnO: Ge) thin films. The films were deposited by sequential sputtering of ZnO and Ge thin film layers on z-cut quartz substrates followed by an ex-situ rapid thermal annealing (RTA) at 600 °C for 30, 60, and 90 s under forming gas atmosphere. Effects of RTA time on the evolution of Ge-ncs were investigated by x-ray diffraction (XRD), scanning electron microscopy (SEM), hard x-ray photoelectron spectroscopy (HAXPES), and extended x-ray absorption fine structure (EXAFS). XRD patterns have clearly shown that fcc diamond phase Ge-ncs of sizes ranging between 18 and 27 nm are formed upon RTA and no Ge-oxide peak has been detected. However, cross-section SEM images have clearly revealed that after RTA process, Ge layers form varying size nanoclusters composed of Ge-ncs regions. EXAFS performed at the Ge K-edge to probe the local atomic structure of the Ge-ncs has revealed that as prepared ZnO:Ge possesses Ge-oxide but subsequent RTA leads to crystalline Ge structure without the oxide layer. In order to study the occupied electronic structure, HAXPES has been utilized. The peak separation between the Zn 2p and Ge 3d shows no significant change due to RTA. This implies little change in the valence band offset due to RTA.

  15. General Atomics | Open Energy Information

    Open Energy Info (EERE)

    Product: General Atomics offers research, development and consulting services to the nuclear industry, including nuclear energy production, manufacturing, defense and related...

  16. Hyper-Ramsey spectroscopy of optical clock transitions

    SciTech Connect (OSTI)

    Yudin, V. I.; Taichenachev, A. V.; Oates, C. W.; Barber, Z. W.; Lemke, N. D.; Ludlow, A. D.; Sterr, U.; Lisdat, Ch.; Riehle, F.

    2010-07-15

    We present nonstandard optical Ramsey schemes that use pulses individually tailored in duration, phase, and frequency to cancel spurious frequency shifts related to the excitation itself. In particular, the field shifts and their uncertainties can be radically suppressed (by two to four orders of magnitude) in comparison with the usual Ramsey method (using two equal pulses) as well as with single-pulse Rabi spectroscopy. Atom interferometers and optical clocks based on two-photon transitions, heavily forbidden transitions, or magnetically induced spectroscopy could significantly benefit from this method. In the latter case, these frequency shifts can be suppressed considerably below a fractional level of 10{sup -17}. Moreover, our approach opens the door for high-precision optical clocks based on direct frequency comb spectroscopy.

  17. Absorption Heat Pumps | Department of Energy

    Broader source: Energy.gov (indexed) [DOE]

    an ammonia-water absorption cycle to provide heating and cooling. As in a standard heat pump, the refrigerant (in this case, ammonia) is condensed in one coil to release its...

  18. Variable effect desorber-resorber absorption cycle

    DOE Patents [OSTI]

    Biermann, Wendell J.

    1985-01-01

    An absorption refrigeration system has an intermediate temperature desorber-resorber pair. A valve between the desorber-resorber pair is modulated to control the capacity for load matching.

  19. Triple-effect absorption chiller cycles

    SciTech Connect (OSTI)

    DeVault, R.C. ); Grossman, G. )

    1992-01-01

    Gas-fired absorption chillers are widely used for air-conditioning buildings. Even the highest efficiency double-effect absorption chillers used more primary energy for air-conditioning buildings than the better electric chillers. Two different triple-effect absorption chiller cycles are capable of substantial performance improvement over equivalent double-effect cycles. One cycle uses two condensers and two absorbers to achieve the triple effect.'' A second cycle, the Double-Condenser Coupled Triple-Effect, uses three condensers as well as a third condenser subcooler (which exchanges heat with the lowest temperature first-effect generator). These triple-effect absorption cycles have the potential to be as energy efficient (on a primary fuel basis) as the best electric chillers. 19 refs.

  20. Absorption chillers: Part of the solution

    SciTech Connect (OSTI)

    Occhionero, A.J. ); Hughes, P.J. ); Reid, E.A. )

    1991-01-01

    Acid rain, ozone depletion, global warming, and implementation economics are considered as they relate to the advisability of expanding the application of absorption chillers. Introductory and background information are provided to put the discussion in the proper context. Then all four issues are discussed separately as they relate to absorption chillers. Acid rain and ozone depletion concerns, and implementation economics, are found to support the expanded use of absorption chillers. The global warming concern is found to be more of a gray area, but the areas of benefit correspond well with the conditions of greatest economic advantage. All things considered, absorption chillers are believed to be part of the environmental and economic solution. It is further believed that integrated resource planning (IRP) processes that consider electric and gas technologies on an equal footing would come to the same conclusion for many regions of the United States. 9 refs., 3 tabs.

  1. Triple-effect absorption chiller cycles

    SciTech Connect (OSTI)

    DeVault, R.C.; Grossman, G.

    1992-06-01

    Gas-fired absorption chillers are widely used for air-conditioning buildings. Even the highest efficiency double-effect absorption chillers used more primary energy for air-conditioning buildings than the better electric chillers. Two different triple-effect absorption chiller cycles are capable of substantial performance improvement over equivalent double-effect cycles. One cycle uses two condensers and two absorbers to achieve the ``triple effect.`` A second cycle, the Double-Condenser Coupled Triple-Effect, uses three condensers as well as a third condenser subcooler (which exchanges heat with the lowest temperature first-effect generator). These triple-effect absorption cycles have the potential to be as energy efficient (on a primary fuel basis) as the best electric chillers. 19 refs.

  2. Atomic Scale Characterization of Compound Semiconductors Using Atom Probe Tomography

    SciTech Connect (OSTI)

    Gorman, B. P.; Norman, A. G.; Lawrence, D.; Prosa, T.; Guthrey, H.; Al-Jassim, M.

    2011-01-01

    Internal interfaces are critical in determining the performance of III-V multijunction solar cells. Studying these interfaces with atomic resolution using a combination of transmission electron microscopy (TEM), atom probe tomography (APT), and density functional calculations enables a more fundamental understanding of carrier dynamics in photovoltaic (PV) device structures. To achieve full atomic scale spatial and chemical resolution, data acquisition parameters in laser pulsed APT must be carefully studied to eliminate surface diffusion. Atom probe data with minimized group V ion clustering and expected stoichiometry can be achieved by adjusting laser pulse power, pulse repetition rate, and specimen preparation parameters such that heat flow away from the evaporating surface is maximized. Applying these improved analysis conditions to III-V based PV gives an atomic scale understanding of compositional and dopant profiles across interfaces and tunnel junctions and the initial stages of alloy clustering and dopant accumulation. Details on APT experimental methods and future in-situ instrumentation developments are illustrated.

  3. An Analysis of Cloud Absorption During

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

    Analysis of Cloud Absorption During ARESE II (Spring 2000) D. M. Powell, R. T. Marchand, and T. P. Ackerman Pacific Northwest National Laboratory Richland, Washington Introduction In early spring 2000, Atmospheric Radiation Measurement (ARM) Program researchers held an intensive operational period (IOP) at the ARM Southern Great Plains (SGP) site. This IOP had several objectives, one of which was to was to re-evaluate (with redundant measurements wherever possible) absorption by low-level

  4. Posters Long-Pathlength Infrared Absorption Measurements

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

    3 Posters Long-Pathlength Infrared Absorption Measurements in the 8- to 14-µm Atmospheric Window: Self-Broadening Coefficient Data T. J. Kulp (a) and J. Shinn Geophysics and Environmental Research Program Lawrence Livermore National Laboratory Livermore, California Introduction The accurate characterization of the latent infrared (IR) absorption in the atmospheric window regions continues to be an area of research interest for the global climate modeling community. In the window between 8 and

  5. Effective atomic numbers and mass attenuation coefficients of some thermoluminescent dosimetric compounds for total photon interaction

    SciTech Connect (OSTI)

    Shivaramu; Amutha, R.; Ramprasath, V.

    1999-05-01

    Effective atomic numbers for total gamma-ray interaction with some selected thermoluminescent dosimetric compounds such as barium acetate, barium sulfate, calcium carbonate, calcium sulfate, calcium sulfate dihydrate, cadmium sulfate (anhydrous), cadmium sulfate, strontium sulfate, and lithium fluoride have been calculated in the 1-keV to 20-MeV energy region. Experimental mass attenuation coefficients and effective atomic numbers for these compounds at selected photon energies of 26.3, 33.2, 59.54, and 661.6 keV have been obtained from good geometry transmission measurements and compared with theoretical values. The effect of absorption edge on effective atomic numbers and its variation with energy, and nonvalidity of the Bragg`s mixture rule at incident photon energies closer to the absorption edges of constituent elements of compounds are discussed.

  6. The Atomic City / The Magic of the Atom - 1950's Atomic Energy Commission Documentary

    ScienceCinema (OSTI)

    None

    2014-07-31

    The story of American cities located near atomic power plants, and steps taken monitoring radiation to ensure the safety of the public who live nearby. .

  7. The Atomic City / The Magic of the Atom - 1950's Atomic Energy Commission Documentary

    SciTech Connect (OSTI)

    2012-06-04

    The story of American cities located near atomic power plants, and steps taken monitoring radiation to ensure the safety of the public who live nearby. .

  8. Anion photoelectron spectroscopy of radicals and clusters

    SciTech Connect (OSTI)

    Travis, Taylor R.

    1999-12-16

    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.

  9. (Resonance ionization spectroscopy)

    SciTech Connect (OSTI)

    Young, J.P.

    1990-10-11

    J. P. Young attended the Fifth International Symposium on Resonance Ionization Spectroscopy and presented an invited oral presentation on research he and coworkers had carried out in applying diode lasers to resonance ionization mass spectrometry. A summary of the conference is given along with an assessment of some of the presentations that the author found of interest. Young also visited Professor Marassi at the University of Camerino to present a seminar and discuss mutual interests in a new molten salt research project of the author. Some of the studies at Camerino are described. Ideas concerning the author's research that came from private discussions are also presented here.

  10. Simulating Cl K-edge X-ray absorption spectroscopy in MCl62-...

    Office of Scientific and Technical Information (OSTI)

    using time-dependent density functional theory Citation Details In-Document Search ... using time-dependent density functional theory We report simulations of the X-ray ...

  11. EGR Spatial Uniformity & Cylinder-Resolved Transients-Measurements using an Absorption Spectroscopy Probe

    Broader source: Energy.gov [DOE]

    This poster describes development and application of an EGR probe for assessing steady-state spatial uniformity and cylinder-resolved EGR dynamics.

  12. A Fern Fatale - X-ray Absorption Spectroscopy Imaging an Arsenic...

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

    accumulate large amounts of it. What is more, the plant converts it to the most toxic inorganic form known. How does it do this? First some background; while there is some...

  13. Catheter based mid-infrared reflectance and reflectance generated absorption spectroscopy

    DOE Patents [OSTI]

    Holman, Hoi-Ying N

    2013-10-29

    A method of characterizing conditions in a tissue, by (a) providing a catheter that has a light source that emits light in selected wavenumbers within the range of mid-IR spectrum; (b) directing the light from the catheter to an area of tissue at a location inside a blood vessel of a subject; (c) collecting light reflected from the location and generating a reflectance spectra; and (d) comparing the reflectance spectra to a reference spectra of normal tissue, whereby a location having an increased number of absorbance peaks at said selected wavenumbers indicates a tissue inside the blood vessel containing a physiological marker for atherosclerosis.

  14. Characterization of the interaction of uranyl ions with humic acids by x-ray absorption spectroscopy

    SciTech Connect (OSTI)

    Reich, T.; Denecke, M.A.; Pompe, S.

    1995-11-01

    Humic substances are present throughout the environment in soil and natural water. They are organic macromolecules with a variable structural formula, molecular weight, and a wide variety of functional groups depending on their origin. In natural waters, humic substances represent the main component of the {open_quotes}dissolved organic carbon{close_quotes} (DOC). The DOC may vary considerably from 1 mg/L at sea water surfaces to 50 mg/L at the surface in dark water swamps. There is strong evidence that all actinides form complexes with humic substances in natural waters. Therefore, humic substances can play an important role in the environmental migration of radionuclides by enhancing their transport. Retardation through humic substance interaction may be also possible due to formation of precipitating agglomerates. For remediation and restoration of contaminated environmental sites and risk assessment of future nuclear waste repositories, it is important to improve the predictive capabilities for radionuclide migration through a better understanding of the interaction of radionuclides with humic substances.

  15. Water-lithium bromide double-effect absorption cooling analysis...

    Office of Scientific and Technical Information (OSTI)

    Water-lithium bromide double-effect absorption cooling analysis Citation Details In-Document Search Title: Water-lithium bromide double-effect absorption cooling analysis You ...

  16. Effects of hydrogen/deuterium absorption on the magnetic properties...

    Office of Scientific and Technical Information (OSTI)

    Effects of hydrogendeuterium absorption on the magnetic properties of CoPd multilayers Citation Details In-Document Search Title: Effects of hydrogendeuterium absorption on the...

  17. Absorption and emission properties of photonic crystals and metamateri...

    Office of Scientific and Technical Information (OSTI)

    ThesisDissertation: Absorption and emission properties of photonic crystals and metamaterials Citation Details In-Document Search Title: Absorption and emission properties of ...

  18. Dataset used to improve liquid water absorption models in the...

    Office of Scientific and Technical Information (OSTI)

    Dataset used to improve liquid water absorption models in the microwave Title: Dataset used to improve liquid water absorption models in the microwave Two datasets, one a ...

  19. XUV Absorption by Solid Density Aluminum (Journal Article) |...

    Office of Scientific and Technical Information (OSTI)

    XUV Absorption by Solid Density Aluminum Citation Details In-Document Search Title: XUV Absorption by Solid Density Aluminum An inverse bremsstrahlung model for plasmas and simple ...

  20. Enhanced Absorption in 2D Materials Via Fano- Resonant Photonic...

    Office of Scientific and Technical Information (OSTI)

    Enhanced Absorption in 2D Materials Via Fano- Resonant Photonic Crystals Citation Details In-Document Search Title: Enhanced Absorption in 2D Materials Via Fano- Resonant Photonic ...

  1. Origins of optical absorption characteristics of Cu2+ complexes...

    Office of Scientific and Technical Information (OSTI)

    Origins of optical absorption characteristics of Cu2+ complexes in solutions Citation Details In-Document Search Title: Origins of optical absorption characteristics of Cu2+ ...

  2. Absorption Spectra and Plotting Exciton Wavefunctions BerkeleyGW...

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

    Hands on Session 5: Converging Absorption Spectra and Plotting Exciton Wavefunctions BerkeleyGW Workshop 11232013 Diana Qiu Converging Absorption General Parameters: K-grid...

  3. Absorption Heat Pump Water Heater - 2013 Peer Review | Department...

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

    Absorption Heat Pump Water Heater - 2013 Peer Review Absorption Heat Pump Water Heater - 2013 Peer Review Emerging Technologies Project for the 2013 Building Technologies Office's ...

  4. Radiance Research Particle Soot/Absorption Photometer Instrument...

    Office of Scientific and Technical Information (OSTI)

    Radiance Research Particle SootAbsorption Photometer Instrument Handbook Citation Details In-Document Search Title: Radiance Research Particle SootAbsorption Photometer ...

  5. CO2 Capture by Absorption with Potassium Carbonate (Technical...

    Office of Scientific and Technical Information (OSTI)

    CO2 Capture by Absorption with Potassium Carbonate Citation Details In-Document Search Title: CO2 Capture by Absorption with Potassium Carbonate You are accessing a document ...

  6. CO2 Capture by Absorption with Potassium Carbonate (Technical...

    Office of Scientific and Technical Information (OSTI)

    Technical Report: CO2 Capture by Absorption with Potassium Carbonate Citation Details In-Document Search Title: CO2 Capture by Absorption with Potassium Carbonate You are ...

  7. Integrated vacuum absorption steam cycle gas separation (Patent...

    Office of Scientific and Technical Information (OSTI)

    vacuum absorption steam cycle gas separation Citation Details In-Document Search Title: Integrated vacuum absorption steam cycle gas separation Methods and systems for separating ...

  8. Spectroscopic study of low-temperature hydrogen absorption in...

    Office of Scientific and Technical Information (OSTI)

    Spectroscopic study of low-temperature hydrogen absorption in palladium Citation Details In-Document Search Title: Spectroscopic study of low-temperature hydrogen absorption in...

  9. Multimode quantum memory based on atomic frequency combs

    SciTech Connect (OSTI)

    Afzelius, Mikael; Simon, Christoph; Riedmatten, Hugues de; Gisin, Nicolas

    2009-05-15

    An efficient multimode quantum memory is a crucial resource for long-distance quantum communication based on quantum repeaters. We propose a quantum memory based on spectral shaping of an inhomogeneously broadened optical transition into an atomic frequency comb (AFC). The spectral width of the AFC allows efficient storage of multiple temporal modes without the need to increase the absorption depth of the storage material, in contrast to previously known quantum memories. Efficient readout is possible thanks to rephasing of the atomic dipoles due to the AFC structure. Long-time storage and on-demand readout is achieved by use of spin states in a lambda-type configuration. We show that an AFC quantum memory realized in solids doped with rare-earth-metal ions could store hundreds of modes or more with close to unit efficiency, for material parameters achievable today.

  10. Auger electron spectroscopy applied to braze wettability

    SciTech Connect (OSTI)

    Chin, R.L.; Larson, D.T.

    1981-01-01

    The initial requirement for brazing is for the liquid metal filler alloy to wet the solid metal surfaces. While atomically clean metal surfaces are not necessary for good wettability, excessive oxygen (metal oxide) and/or carbon contaminants will leave non-wettable surfaces. The causes of non-wettable surfaces during brazing have been examined utilizing Auger electron spectroscopy. This surface spectroscopy with a sampling depth of 10 to 20A combined with sputter etching to provide film profiles was used to examine non-wettable specimens. Three different systems were studied. In the first case, carbon was found to segregate from the bulk to the surface of a nickel-copper alloy (Monel) during the braze heating. The formation of a graphitic layer was responsible for the non-wettability. In the second case, an external carbon contaminant was found on the surface of 316 stainless steel and resulted in a non-wettable surface. In the third situation, the non-wettability of 304 stainless steel was caused by a thick oxide film which formed in vacuum during brazing.

  11. Reverse photoacoustic standoff spectroscopy

    DOE Patents [OSTI]

    Van Neste, Charles W.; Senesac, Lawrence R.; Thundat, Thomas G.

    2011-04-12

    A system and method are disclosed for generating a reversed photoacoustic spectrum at a greater distance. A source may emit a beam to a target and a detector measures signals generated as a result of the beam being emitted on the target. By emitting a chopped/pulsed light beam to the target, it may be possible to determine the target's optical absorbance by monitoring the intensity of light collected at the detector at different wavelengths. As the wavelength of light is changed, the target may absorb or reject each optical frequency. Rejection may increase the intensity at the sensing element and absorption may decrease the intensity. Accordingly, an identifying spectrum of the target may be made with the intensity variation of the detector as a function of illuminating wavelength.

  12. Photoacoustic point spectroscopy

    SciTech Connect (OSTI)

    Van Neste, Charles W.; Senesac, Lawrence R.; Thundat, Thomas G.

    2011-06-14

    A system and method are disclosed for generating a photoacoustic spectrum in an open or closed environment with reduced noise. A source may emit a beam to a target substance coated on a detector that measures acoustic waves generated as a result of a light beam being absorbed by the target substance. By emitting a chopped/pulsed light beam to the target substance on the detector, it may be possible to determine the target's optical absorbance as the wavelength of light is changed. Rejection may decrease the intensity of the acoustic waves on the detector while absorption may increase the intensity. Accordingly, an identifying spectrum of the target may be made with the intensity variation of the detector as a function of illuminating wavelength.

  13. Multilayer graphene stacks grown by different methods-thickness measurements by X-ray diffraction, Raman spectroscopy and optical transmission

    SciTech Connect (OSTI)

    Tokarczyk, M. Kowalski, G.; Kępa, H.; Grodecki, K.; Drabińska, A.; Strupiński, W.

    2013-12-15

    X-ray diffraction, Raman spectroscopy and Optical absorption estimates of the thickness of graphene multi layer stacks (number of graphene layers) are presented for three different growth techniques. The objective of this work was focused on comparison and reconciliation of the two already widely used methods for thickness estimates (Raman and Absorption) with the calibration of the X-ray method as far as Scherer constant K is concerned and X-ray based Wagner-Aqua extrapolation method.

  14. In-situ control system for atomization

    DOE Patents [OSTI]

    Anderson, I.E.; Figliola, R.S.; Terpstra, R.L.

    1995-06-13

    Melt atomizing apparatus comprising a melt supply orifice for supplying the melt for atomization and gas supply orifices proximate the melt supply orifice for supplying atomizing gas to atomize the melt as an atomization spray is disclosed. The apparatus includes a sensor, such as an optical and/or audio sensor, for providing atomization spray data, and a control unit responsive to the sensed atomization spray data for controlling at least one of the atomizing gas pressure and an actuator to adjust the relative position of the gas supply orifice and melt supply in a manner to achieve a desired atomization spray. 3 figs.

  15. In-situ control system for atomization

    DOE Patents [OSTI]

    Anderson, Iver E.; Figliola, Richard S.; Terpstra, Robert L.

    1995-06-13

    Melt atomizing apparatus comprising a melt supply orifice for supplying the melt for atomization and gas supply orifices proximate the melt supply orifice for supplying atomizing gas to atomize the melt as an atomization spray. The apparatus includes a sensor, such as an optical and/or audio sensor, for providing atomization spray data, and a control unit responsive to the sensed atomization spray data for controlling at least one of the atomizing gas pressure and an actuator to adjust the relative position of the gas supply orifice and melt supply in a manner to achieve a desired atomization spray.

  16. Array-based photoacoustic spectroscopy

    DOE Patents [OSTI]

    Autrey, S. Thomas; Posakony, Gerald J.; Chen, Yu

    2005-03-22

    Methods and apparatus for simultaneous or sequential, rapid analysis of multiple samples by photoacoustic spectroscopy are disclosed. A photoacoustic spectroscopy sample array including a body having at least three recesses or affinity masses connected thereto is used in conjunction with a photoacoustic spectroscopy system. At least one acoustic detector is positioned near the recesses or affinity masses for detection of acoustic waves emitted from species of interest within the recesses or affinity masses.

  17. Supersonic coal water slurry fuel atomizer

    DOE Patents [OSTI]

    Becker, Frederick E.; Smolensky, Leo A.; Balsavich, John

    1991-01-01

    A supersonic coal water slurry atomizer utilizing supersonic gas velocities to atomize coal water slurry is provided wherein atomization occurs externally of the atomizer. The atomizer has a central tube defining a coal water slurry passageway surrounded by an annular sleeve defining an annular passageway for gas. A converging/diverging section is provided for accelerating gas in the annular passageway to supersonic velocities.

  18. Simulating a 4-effect absorption chiller

    SciTech Connect (OSTI)

    Grossman, G.; Zaltash, A.; Adcock, P.W.; DeVault, R.C.

    1995-06-01

    Absorption chillers are heat-operated refrigeration machines that operate on one of the earliest known principles of refrigeration. Current absorption chillers typically use either steam or a gas-fired burner as the energy source. All current gas-fired absorption cooling systems are based on the well known single-effect or double-effect cycles. To further improve utilization of the high temperature heat available from natural gas, a variety of triple-effect cycles have been proposed and are being developed that are capable of substantial performance improvement over equivalent double-effect cycles. This article describes a study that investigated the possibility of even further improving utilization of the high temperature heat available from natural gas combustion. During the study, performance simulation was conducted for a 4-effect lithium bromide/water cycle. From an environmental perspective, absorption chillers provide several benefits. They use absorption pairs (such as lithium bromide/water) as the working fluids, rather than chlorofluorocarbons or hydrochlorofluorocarbons, which contribute to ozone depletion and global warming.

  19. Measurement and modeling of a diamond deposition reactor: Hydrogen atom and electron number densities in an Ar/H{sub 2} arc jet discharge

    SciTech Connect (OSTI)

    Rennick, C.J.; Engeln, R.; Smith, J.A.; Orr-Ewing, A.J.; Ashfold, M.N.R.; Mankelevich, Yu.A.

    2005-06-01

    A combination of experiment [optical emission and cavity ring-down spectroscopy (CRDS) of electronically excited H atoms] and two-dimensional (2D) modeling has enabled a uniquely detailed characterization of the key properties of the Ar/H{sub 2} plasma within a {<=}10-kW, twin-nozzle dc arc jet reactor. The modeling provides a detailed description of the initial conditions in the primary torch head and of the subsequent expansion of the plasma into the lower pressure reactor chamber, where it forms a cylindrical plume of activated gas comprising mainly of Ar, Ar{sup +}, H, ArH{sup +}, and free electrons. Subsequent reactions lead to the formation of H{sub 2} and electronically excited atoms, including H(n=2) and H(n=3) that radiate photons, giving the plume its characteristic intense emission. The modeling successfully reproduces the measured spatial distributions of H(n>1) atoms, and their variation with H{sub 2} flow rate, F{sub H{sub 2}}{sup 0}. Computed H(n=2) number densities show near-quantitative agreement with CRDS measurements of H(n=2) absorption via the Balmer-{beta} transition, successfully capturing the observed decrease in H(n=2) density with increased F{sub H{sub 2}}{sup 0}. Stark broadening of the Balmer-{beta} transition depends upon the local electron density in close proximity to the H(n=2) atoms. The modeling reveals that, at low F{sub H{sub 2}}{sup 0}, the maxima in the electron and H(n=2) atom distributions occur in different spatial regions of the plume; direct analysis of the Stark broadening of the Balmer-{beta} line would thus lead to an underestimate of the peak electron density. The present study highlights the necessity of careful intercomparisons between quantitative experimental data and model predictions in the development of a numerical treatment of the arc jet plasma. The kinetic scheme used here succeeds in describing many disparate observations--e.g., electron and H(n=2) number densities, spatial distributions of optical emission

  20. spectroscopy | National Nuclear Security Administration

    National Nuclear Security Administration (NNSA)

    spectroscopy Researcher from NNSA lab helps develop new system for instant explosive detection Chemicals used in explosives give off signatures that can be read by spectroscopic ...

  1. Los Alamos National Laboratory ATOMIC PHOTOGRAPHY ATOMIC PHOTOGRAPHY

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

    ATOMIC PHOTOGRAPHY ATOMIC PHOTOGRAPHY BLASTS FROM THE PAST BLASTS FROM THE PAST Twenty-five U.S. atmospheric nuclear weapons operations (each a series of tests) were conducted from 1945 to 1963, primarily at the Pacific Proving Grounds and at the Nevada Test Site, southeastern Nevada. Below, observers witness Operation Greenhouse, Eniwetok Atoll, spring 1951. Greenhouse was a series of four tests. 17 Proof of principle for thermonuclear weapons, the 225-kiloton George test, May 8, 1951, of

  2. Femtosecond Coherent Anti-Stokes Raman Spectroscopy (CARS) As Next Generation Nonlinear LIDAR Spectroscopy and Microscopy

    SciTech Connect (OSTI)

    Ooi, C. H. Raymond

    2009-07-10

    Nonlinear spectroscopy using coherent anti-Stokes Raman scattering and femtosecond laser pulses has been successfully developed as powerful tools for chemical analysis and biological imaging. Recent developments show promising possibilities of incorporating CARS into LIDAR system for remote detection of molecular species in airborne particles. The corresponding theory is being developed to describe nonlinear scattering of a mesoscopic particle composed of complex molecules by laser pulses with arbitrary shape and spectral content. Microscopic many-body transform theory is used to compute the third order susceptibility for CARS in molecules with known absorption spectrum and vibrational modes. The theory is combined with an integral scattering formula and Mie-Lorentz formulae, giving a rigorous formalism which provides powerful numerical experimentation of CARS spectra, particularly on the variations with the laser parameters and the direction of detection.

  3. Plasmon absorption modulator systems and methods

    DOE Patents [OSTI]

    Kekatpure, Rohan Deodatta; Davids, Paul

    2014-07-15

    Plasmon absorption modulator systems and methods are disclosed. A plasmon absorption modulator system includes a semiconductor substrate, a plurality of quantum well layers stacked on a top surface of the semiconductor substrate, and a metal layer formed on a top surface of the stack of quantum well layers. A method for modulating plasmonic current includes enabling propagation of the plasmonic current along a metal layer, and applying a voltage across the stack of quantum well layers to cause absorption of a portion of energy of the plasmonic current by the stack of quantum well layers. A metamaterial switching system includes a semiconductor substrate, a plurality of quantum well layers stacked on a top surface of the semiconductor substrate, and at least one metamaterial structure formed on a top surface of the stack of quantum well layers.

  4. Nanofibrous membrane-based absorption refrigeration system

    SciTech Connect (OSTI)

    Isfahani, RN; Sampath, K; Moghaddam, S

    2013-12-01

    This paper presents a study on the efficacy of highly porous nanofibrous membranes for application in membrane-based absorbers and desorbers. Permeability studies showed that membranes with a pore size greater than about one micron have a sufficient permeability for application in the absorber heat exchanger. Membranes with smaller pores were found to be adequate for the desorber heat exchanger. The membranes were implemented in experimental membrane-based absorber and desorber modules and successfully tested. Parametric studies were conducted on both absorber and desorber processes. Studies on the absorption process were focused on the effects of water vapor pressure, cooling water temperature, and the solution velocity on the absorption rate. Desorption studies were conducted on the effects of wall temperature, vapor and solution pressures, and the solution velocity on the desorption rate. Significantly higher absorption and desorption rates than in the falling film absorbers and desorbers were achieved. Published by Elsevier Ltd.

  5. Resonant ultrasound spectroscopy

    DOE Patents [OSTI]

    Migliori, Albert

    1991-01-01

    A resonant ultrasound spectroscopy method provides a unique characterization of an object for use in distinguishing similar objects having physical differences greater than a predetermined tolerance. A resonant response spectrum is obtained for a reference object by placing excitation and detection transducers at any accessible location on the object. The spectrum is analyzed to determine the number of resonant response peaks in a predetermined frequency interval. The distribution of the resonance frequencies is then characterized in a manner effective to form a unique signature of the object. In one characterization, a small frequency interval is defined and stepped though the spectrum frequency range. Subsequent objects are similarly characterized where the characterizations serve as signatures effective to distinguish objects that differ from the reference object by more than the predetermined tolerance.

  6. Application of Raman spectroscopy to high-temperature analytical measurements

    SciTech Connect (OSTI)

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

    1997-01-01

    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.

  7. Real-time multiplexed digital cavity-enhanced spectroscopy

    SciTech Connect (OSTI)

    Boyson, Toby K.; Dagdigian, Paul J.; Pavey, Karl D.; Fitzgerald, Nicholas J.; Spence, Thomas G.; Moore, David S.; Harb, Charles C.

    2015-10-01

    Cavity-enhanced spectroscopy is a sensitive optical absorption technique but one where the practical applications have been limited to studying small wavelength ranges. In addition, this Letter shows that wideband operation can be achieved by combining techniques usually reserved for the communications community with that of cavity-enhanced spectroscopy, producing a multiplexed real-time cavity-enhanced spectrometer. We use multiple collinear laser sources operating asynchronously and simultaneously while being detected on a single photodetector. This is synonymous with radio frequency (RF) cellular systems in which signals are detected on a single antenna but decoded uniquely. Here, we demonstrate results with spectra of methyl salicylate and show parts-per-billion per root hertz sensitivity measured in real-time.

  8. Real-time multiplexed digital cavity-enhanced spectroscopy

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

    Boyson, Toby K.; Dagdigian, Paul J.; Pavey, Karl D.; Fitzgerald, Nicholas J.; Spence, Thomas G.; Moore, David S.; Harb, Charles C.

    2015-10-01

    Cavity-enhanced spectroscopy is a sensitive optical absorption technique but one where the practical applications have been limited to studying small wavelength ranges. In addition, this Letter shows that wideband operation can be achieved by combining techniques usually reserved for the communications community with that of cavity-enhanced spectroscopy, producing a multiplexed real-time cavity-enhanced spectrometer. We use multiple collinear laser sources operating asynchronously and simultaneously while being detected on a single photodetector. This is synonymous with radio frequency (RF) cellular systems in which signals are detected on a single antenna but decoded uniquely. Here, we demonstrate results with spectra of methyl salicylatemore » and show parts-per-billion per root hertz sensitivity measured in real-time.« less

  9. ATOMIC ENERGY ACT OF 1946

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

    D. Niisc AEC Hcadqoartcrs Library Voliiinc I Principal Docriiiiciits U.S. ATOMIC ENERGY COMMISSION WASHINGTON, 1965 PUBLIC LAW 5 8 5 - 7 9 CONQRESS CHAPTER 724-2 ...

  10. Imaging atoms in 3-D

    ScienceCinema (OSTI)

    Ercius, Peter

    2014-06-27

    Berkeley Lab's Peter Ercius discusses "Imaging atoms in 3-D" in this Oct. 28, 2013 talk, which is part of a Science at the Theater event entitled Eight Big Ideas

  11. Efimov physics in cold atoms

    SciTech Connect (OSTI)

    Braaten, Eric . E-mail: braaten@mps.ohio-state.edu; Hammer, H.-W. . E-mail: hammer@itkp.uni-bonn.de

    2007-01-15

    Atoms with a large scattering length have universal low-energy properties that do not depend on the details of their structure or their interactions at short distances. In the 2-atom sector, the universal properties are familiar and depend only on the scattering length. In the 3-atom sector for identical bosons, the universal properties include the existence of a sequence of shallow triatomic molecules called Efimov trimers and log-periodic dependence of scattering observables on the energy and the scattering length. In this review, we summarize the universal results that are currently known. We also summarize the experimental information that is currently available with an emphasis on 3-atom loss processes.

  12. Theoretical studies of atomic transitions

    SciTech Connect (OSTI)

    Fischer, C.F.

    1990-10-01

    This paper discusses: lifetime of excited states; core-polarization studies; large relativistic calculations; Monte Carlo Hartree-Fock (MCHF) atomic structure package; and MCHF codes for the hypercube. (LSP)

  13. UNITED STATES ATOMIC ENERGY COMMISSION

    Office of Legacy Management (LM)

    I(S.0 -01: SPECIAL NUCLEAR MATERIAL LlCEWSE Pursuant to the Atomic Energy Act of 1954 and Title 10, Code of Federal Regulations, Chapter 1, Part 70, "Special Nuclear Material ...

  14. u. S. Atomic Energy Commission

    Office of Legacy Management (LM)

    S. Atomic Energy Commission R. 0. Box 30, Ansonia Station New York ES, N. Y. MATERIALS 5+k& hJf Reference: SK:BL Attention: Mr. R. J. Smith Jr. Director Special Materials Division ...

  15. Laser isotope separation by multiple photon absorption

    DOE Patents [OSTI]

    Robinson, C. Paul; Rockwood, Stephen D.; Jensen, Reed J.; Lyman, John L.; Aldridge, III, Jack P.

    1987-01-01

    Multiple photon absorption from an intense beam of infrared laser light may be used to induce selective chemical reactions in molecular species which result in isotope separation or enrichment. The molecular species must have a sufficient density of vibrational states in its vibrational manifold that, is the presence of sufficiently intense infrared laser light tuned to selectively excite only those molecules containing a particular isotope, multiple photon absorption can occur. By this technique, for example, intense CO.sub.2 laser light may be used to highly enrich .sup.34 S in natural SF.sub.6 and .sup.11 B in natural BCl.sub.3.

  16. Laser isotope separation by multiple photon absorption

    DOE Patents [OSTI]

    Robinson, C. Paul; Rockwood, Stephen D.; Jensen, Reed J.; Lyman, John L.; Aldridge, III, Jack P.

    1977-01-01

    Multiple photon absorption from an intense beam of infrared laser light may be used to induce selective chemical reactions in molecular species which result in isotope separation or enrichment. The molecular species must have a sufficient density of vibrational states in its vibrational manifold that, in the presence of sufficiently intense infrared laser light tuned to selectively excite only those molecules containing a particular isotope, multiple photon absorption can occur. By this technique, for example, intense CO.sub.2 laser light may be used to highly enrich .sup.34 S in natural SF.sub.6 and .sup.11 B in natural BCl.sub.3.

  17. Laser isotope separation by multiple photon absorption

    DOE Patents [OSTI]

    Robinson, C.P.; Rockwood, S.D.; Jensen, R.J.; Lyman, J.L.; Aldridge, J.P. III.

    1987-04-07

    Multiple photon absorption from an intense beam of infrared laser light may be used to induce selective chemical reactions in molecular species which result in isotope separation or enrichment. The molecular species must have a sufficient density of vibrational states in its vibrational manifold that, is the presence of sufficiently intense infrared laser light tuned to selectively excite only those molecules containing a particular isotope, multiple photon absorption can occur. By this technique, for example, intense CO[sub 2] laser light may be used to highly enrich [sup 34]S in natural SF[sub 6] and [sup 11]B in natural BCl[sub 3]. 8 figs.

  18. Carbon nanotube forests growth using catalysts from atomic layer deposition

    SciTech Connect (OSTI)

    Chen, Bingan; Zhang, Can; Esconjauregui, Santiago; Xie, Rongsi; Zhong, Guofang; Robertson, John; Bhardwaj, Sunil; Cepek, Cinzia

    2014-04-14

    We have grown carbon nanotubes using Fe and Ni catalyst films deposited by atomic layer deposition. Both metals lead to catalytically active nanoparticles for growing vertically aligned nanotube forests or carbon fibres, depending on the growth conditions and whether the substrate is alumina or silica. The resulting nanotubes have narrow diameter and wall number distributions that are as narrow as those grown from sputtered catalysts. The state of the catalyst is studied by in-situ and ex-situ X-ray photoemission spectroscopy. We demonstrate multi-directional nanotube growth on a porous alumina foam coated with Fe prepared by atomic layer deposition. This deposition technique can be useful for nanotube applications in microelectronics, filter technology, and energy storage.

  19. Collisional shifts in optical-lattice atom clocks

    SciTech Connect (OSTI)

    Band, Y. B. [Department of Chemistry, Ben-Gurion University of the Negev, Beer-Sheva 84105 (Israel); Atomic Physics Division, A267 Physics, National Institute of Standards and Technology, Gaithersburg, Maryland 20899 (United States); Ilse Katz Center for Nano-Science, Ben-Gurion University of the Negev, Beer-Sheva 84105 (Israel); Vardi, A. [Department of Chemistry, Ben-Gurion University of the Negev, Beer-Sheva 84105 (Israel)

    2006-09-15

    We theoretically study the effects of elastic collisions on the determination of frequency standards via Ramsey-fringe spectroscopy in optical-lattice atom clocks. Interparticle interactions of bosonic atoms in multiply occupied lattice sites can cause a linear frequency shift, as well as generate asymmetric Ramsey-fringe patterns and reduce fringe visibility due to interparticle entanglement. We propose a method of reducing these collisional effects in an optical lattice by introducing a phase difference of {pi} between the Ramsey driving fields in adjacent sites. This configuration suppresses site-to-site hopping due to interference of two tunneling pathways, without degrading fringe visibility. Consequently, the probability of double occupancy is reduced, leading to cancellation of collisional shifts.

  20. Electrohydrodynamic atomization (EHDA) assisted wet chemical synthesis of nickel nanoparticles

    SciTech Connect (OSTI)

    Barzegar Vishlaghi, M. [Department of Mechanical Engineering, University of Tabriz, Tabriz (Iran, Islamic Republic of)] [Department of Mechanical Engineering, University of Tabriz, Tabriz (Iran, Islamic Republic of); Farzalipour Tabriz, M., E-mail: meisam.fa@gmail.com [Department of Mechanical Engineering, University of Tabriz, Tabriz (Iran, Islamic Republic of); Mohammad Moradi, O. [Department of Mechanical Engineering, University of Tabriz, Tabriz (Iran, Islamic Republic of)] [Department of Mechanical Engineering, University of Tabriz, Tabriz (Iran, Islamic Republic of)

    2012-07-15

    Highlights: ? Electrohydrodynamic atomization (EHDA) assisted chemical synthesis of nickel nanoparticles is reported. ? Substituting water with non-aqueous media prevents the formation of nickel hydroxide. ? Size of particles decreased from 10 to 20 nm down to 24 nm by using multi-jet mode. ? Synthesized nanoparticles have diffraction patterns similar to amorphous materials. -- Abstract: In this study nickel nanoparticles were prepared via chemical reduction of nickel acetate using sodium borohydride using electrohydrodynamic atomization (EHDA) technique. This technique was used to spray a finely dispersed aerosol of nickel precursor solution into the reductive bath. Obtained particles were characterized by means of X-ray diffraction (XRD), UVVisible spectroscopy, and transmission electron microscopy (TEM). Results confirmed the formation of nickel nanoparticles and showed that applying EHDA technique to chemical reduction method results in producing smaller particles with narrower size distribution in comparison with conventional reductive precipitation method.

  1. Direct visualization of atomically precise nitrogen-doped graphene nanoribbons

    SciTech Connect (OSTI)

    Zhang, Yi; Zhang, Yanfang; Li, Geng; Lu, Jianchen; Du, Shixuan, E-mail: sxdu@iphy.ac.cn, E-mail: feng@mpip-mainz.mpg.de; Gao, Hong-Jun [Institute of Physics and University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing 100190 (China); Lin, Xiao [University of Chinese Academy of Sciences and Institute of Physics, Chinese Academy of Sciences, Beijing 100049 (China); Berger, Reinhard; Feng, Xinliang, E-mail: sxdu@iphy.ac.cn, E-mail: feng@mpip-mainz.mpg.de; Mllen, Klaus [Max Planck Institute for Polymer Research, Ackermannweg 10, D-55128 Mainz (Germany)

    2014-07-14

    We have fabricated atomically precise nitrogen-doped chevron-type graphene nanoribbons by using the on-surface synthesis technique combined with the nitrogen substitution of the precursors. Scanning tunneling microscopy and spectroscopy indicate that the well-defined nanoribbons tend to align with the neighbors side-by-side with a band gap of 1.02?eV, which is in good agreement with the density functional theory calculation result. The influence of the high precursor coverage on the quality of the nanoribbons is also studied. We find that graphene nanoribbons with sufficient aspect ratios can only be fabricated at sub-monolayer precursor coverage. This work provides a way to construct atomically precise nitrogen-doped graphene nanoribbons.

  2. Absorption experiments on x-ray-heated mid-{ital Z} constrained samples

    SciTech Connect (OSTI)

    Perry, T.S.; Springer, P.T.; Fields, D.F.; Bach, D.R.; Serduke, F.J.; Iglesias, C.A.; Rogers, F.J.; Nash, J.K.; Chen, M.H.; Wilson, B.G.; Goldstein, W.H.; Rozsynai, B.; Ward, R.A.; Kilkenny, J.D.; Doyas, R.; Da Silva, L.B.; Back, C.A.; Cauble, R.; Davidson, S.J.; Foster, J.M.; Smith, C.C.; Bar-Shalom, A.; Lee, R.W.

    1996-11-01

    Results of a niobium absorption experiment are presented that represent a major step in the development of techniques necessary for the quantitative characterization of hot, dense matter. The general requirements for performing quantitative analyses of absorption spectra are discussed. Hydrodynamic simulations are used to illustrate the behavior of tamped x-ray-heated matter and to indicate potential two-dimensional problems inherent in the technique. The absorption spectrum of a low-{ital Z} material, in this case aluminum, mixed with niobium provides a temperature diagnostic, which together with radiography as a density diagnostic fully characterizes the sample. A discussion is presented of opacity calculations and a comparison to the measurements is given that illustrates the need for experiments to provide a critical test of theory. The experimental technique is placed in context with a review of previous measurements using absorption spectroscopy to probe hot, dense matter. It is shown that the overall experimental concepts, although understood, were not always achieved in previous experiments. {copyright} {ital 1996 The American Physical Society.}

  3. Saturated absorption in a rotational molecular transition at 2.5 THz using a quantum cascade laser

    SciTech Connect (OSTI)

    Consolino, L. Campa, A.; Ravaro, M.; Mazzotti, D.; Bartalini, S.; De Natale, P.; Vitiello, M. S.

    2015-01-12

    We report on the evidence of saturation effects in a rotational transition of CH{sub 3}OH around 2.5?THz, induced by a free-running continuous-wave quantum cascade laser (QCL). The QCL emission is used for direct-absorption spectroscopy experiments, allowing to study the dependence of the absorption coefficient on gas pressure and laser intensity. A saturation intensity of 25??W/mm{sup 2}, for a gas pressure of 17??bar, is measured. This result represents the initial step towards the implementation of a QCL-based high-resolution sub-Doppler THz spectroscopy, which is expected to improve by orders of magnitude the precision of THz spectrometers.

  4. Oxygen Atom Adsorption on and Diffusion into Nb(110) and Nb(100) from First Principles

    SciTech Connect (OSTI)

    Tafen, De Nyago; Gao, Michael C.

    2013-11-01

    In order to understand the dynamics of oxidation of Nb, we examine the adsorption, absorption, and diffusion of an oxygen atom on, in, and into Nb(110) and Nb(100) surfaces, respectively, using density functional theory. Our calculations predict that the oxygen atom adsorbs on the threefold site on Nb(110) and the fourfold hollow site on Nb(100), and the adsorption energy is -5.08 and -5.18 eV respectively. We find the long and short bridge sites to be transition states for O diffusion on Nb(110), while the on top site is a rank-2 saddle point. In the subsurface region, the oxygen atom prefers the octahedral site, as in bulk niobium. Our results also show that the O atom is more stable on Nb(110) subsurface than on Nb(100) subsurface. The diffusion of oxygen atoms into niobium surfaces passes through transition states where the oxygen atom is coordinated to four niobium atoms. The diffusion barriers of the oxygen atom into Nb(110) and Nb(100) are 1.81 and 2.05 eV, respectively. Analysis of the electronic density of states reveals the emergence of well localized electronic states below the lowest states of clean Nb surfaces due to d-p orbital hybridization.

  5. Infrared Spectroscopy of Explosives Residues: Measurement Techniques and Spectral Analysis

    SciTech Connect (OSTI)

    Phillips, Mark C.; Bernacki, Bruce E.

    2015-03-11

    Infrared laser spectroscopy of explosives is a promising technique for standoff and non-contact detection applications. However, the interpretation of spectra obtained in typical standoff measurement configurations presents numerous challenges. Understanding the variability in observed spectra from explosives residues and particles is crucial for design and implementation of detection algorithms with high detection confidence and low false alarm probability. We discuss a series of infrared spectroscopic techniques applied toward measuring and interpreting the reflectance spectra obtained from explosives particles and residues. These techniques utilize the high spectral radiance, broad tuning range, rapid wavelength tuning, high scan reproducibility, and low noise of an external cavity quantum cascade laser (ECQCL) system developed at Pacific Northwest National Laboratory. The ECQCL source permits measurements in configurations which would be either impractical or overly time-consuming with broadband, incoherent infrared sources, and enables a combination of rapid measurement speed and high detection sensitivity. The spectroscopic methods employed include standoff hyperspectral reflectance imaging, quantitative measurements of diffuse reflectance spectra, reflection-absorption infrared spectroscopy, microscopic imaging and spectroscopy, and nano-scale imaging and spectroscopy. Measurements of explosives particles and residues reveal important factors affecting observed reflectance spectra, including measurement geometry, substrate on which the explosives are deposited, and morphological effects such as particle shape, size, orientation, and crystal structure.

  6. X-ray absorption spectroscopic studies of mononuclear non-heme iron enzymes

    SciTech Connect (OSTI)

    Westre, T.E.

    1996-01-01

    Fe-K-edge X-ray absorption spectroscopy (XAS) has been used to investigate the electronic and geometric structure of the iron active site in non-heme iron enzymes. A new theoretical extended X-ray absorption fine structure (EXAFS) analysis approach, called GNXAS, has been tested on data for iron model complexes to evaluate the utility and reliability of this new technique, especially with respect to the effects of multiple-scattering. In addition, a detailed analysis of the 1s{yields}3d pre-edge feature has been developed as a tool for investigating the oxidation state, spin state, and geometry of iron sites. Edge and EXAFS analyses have then been applied to the study of non-heme iron enzyme active sites.

  7. The light meson spectroscopy program

    SciTech Connect (OSTI)

    Smith, Elton S.

    2014-06-01

    Recent discoveries of a number of unexpected new charmomium-like meson states at the BaBar and Belle B-factories have demonstrated how little is still known about meson spectroscopy. In this talk we will review recent highlights of the light quark spectroscopy from collider and fixed target experiments.

  8. Fundamental Electroweak Studies using Trapped Ions & Atoms

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

    collaboration performs fundamental electroweak studies on trapped ions & atoms. We use neutral atom and ion trapping techniques at radioactive ion beam facilities here and...

  9. Manhattan Project: Atomic Discoveries, 1890s-1939

    Office of Scientific and Technical Information (OSTI)

    The exact nature of these atoms remained elusive, however, despite centuries of attempts ... Explorations into the nature of the atom from 1919 to 1932 confirmed this new model, ...

  10. Atomic Photography: Blasts from the Past

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

    Atomic Photography National Security Science Latest Issue:July 2015 past issues All Issues submit Atomic Photography: Blasts from the Past A gallery of images reveals the weird...

  11. Direct fired absorption machine flue gas recuperator

    DOE Patents [OSTI]

    Reimann, Robert C.; Root, Richard A.

    1985-01-01

    A recuperator which recovers heat from a gas, generally the combustion gas of a direct-fired generator of an absorption machine. The recuperator includes a housing with liquid flowing therethrough, the liquid being in direct contact with the combustion gas for increasing the effectiveness of the heat transfer between the gas and the liquid.

  12. Coupled dual loop absorption heat pump

    DOE Patents [OSTI]

    Sarkisian, Paul H.; Reimann, Robert C.; Biermann, Wendell J.

    1985-01-01

    A coupled dual loop absorption system which utilizes two separate complete loops. Each individual loop operates at three temperatures and two pressures. This low temperature loop absorber and condenser are thermally coupled to the high temperature loop evaporator, and the high temperature loop condenser and absorber are thermally coupled to the low temperature generator.

  13. Corrosion inhibitor for aqueous ammonia absorption system

    DOE Patents [OSTI]

    Phillips, Benjamin A.; Whitlow, Eugene P.

    1998-09-22

    A method of inhibiting corrosion and the formation of hydrogen and thus improving absorption in an ammonia/water absorption refrigeration, air conditioning or heat pump system by maintaining the hydroxyl ion concentration of the aqueous ammonia working fluid within a selected range under anaerobic conditions at temperatures up to 425.degree. F. This hydroxyl ion concentration is maintained by introducing to the aqueous ammonia working fluid an inhibitor in an amount effective to produce a hydroxyl ion concentration corresponding to a normality of the inhibitor relative to the water content ranging from about 0.015 N to about 0.2 N at 25.degree. C. Also, working fluids for inhibiting the corrosion of carbon steel and resulting hydrogen formation and improving absorption in an ammonia/water absorption system under anaerobic conditions at up to 425.degree. F. The working fluids may be aqueous solutions of ammonia and a strong base or aqueous solutions of ammonia, a strong base, and a specified buffer.

  14. Corrosion inhibitor for aqueous ammonia absorption system

    DOE Patents [OSTI]

    Phillips, B.A.; Whitlow, E.P.

    1998-09-22

    A method is described for inhibiting corrosion and the formation of hydrogen and thus improving absorption in an ammonia/water absorption refrigeration, air conditioning or heat pump system by maintaining the hydroxyl ion concentration of the aqueous ammonia working fluid within a selected range under anaerobic conditions at temperatures up to 425 F. This hydroxyl ion concentration is maintained by introducing to the aqueous ammonia working fluid an inhibitor in an amount effective to produce a hydroxyl ion concentration corresponding to a normality of the inhibitor relative to the water content ranging from about 0.015 N to about 0.2 N at 25 C. Also, working fluids for inhibiting the corrosion of carbon steel and resulting hydrogen formation and improving absorption in an ammonia/water absorption system under anaerobic conditions at up to 425 F. The working fluids may be aqueous solutions of ammonia and a strong base or aqueous solutions of ammonia, a strong base, and a specified buffer. 5 figs.

  15. Absorption machine with desorber-resorber

    DOE Patents [OSTI]

    Biermann, Wendell J.

    1985-01-01

    An absorption refrigeration system utilizing a low temperature desorber and intermediate temperature resorber. The system operates at three temperatures and three pressures to increase the efficiency of the system and is capable of utilizing a lower generator temperature than previously used.

  16. A narrow window of Rabi frequency for competition between electromagnetically induced transparency and Raman absorption

    SciTech Connect (OSTI)

    Chang, Ray-Yuan; Fang, Wei-Chia; Lee, Ming-Tsung; He, Zong-Syun; Ke, Bai-Cian; Lee, Yi-Chi; Tsai, Chin-Chun

    2010-01-15

    This investigation clarifies the transition phenomenon between the electromagnetically induced transparency (EIT) and Raman absorption in a ladder-type system of Doppler-broadened cesium vapor. A competition window of this transition was found to be as narrow as 2 MHz defined by the probe Rabi frequency. For a weak probe, the spectrum of EIT associated with quantum interference suggests that the effect of the Doppler velocity on the spectrum is negligible. When the Rabi frequency of the probe becomes comparable with the effective decay rate, an electromagnetically induced absorption (EIA) dip emerges at the center of the power broadened EIT peak. While the Rabi frequency of the probe exceeds the effective decay rate, decoherence that is generated by the intensified probe field occurs and Raman absorption dominates the interaction process, yielding a pure absorption spectrum; the Doppler velocity plays an important role in the interaction. A theory that is based on density matrix simulation, with or without the Doppler effect, can qualitatively fit the experimental data. In this work, the coherence of atom-photon interactions is created or destroyed using the probe Rabi frequency as a decoherence source.

  17. A doubly curved elliptical crystal spectrometer for the study of localized x-ray absorption in hot plasmas

    SciTech Connect (OSTI)

    Cahill, Adam D. Hoyt, Cad L.; Pikuz, Sergei A.; Shelkovenko, Tania; Hammer, David A.

    2014-10-15

    X-ray absorption spectroscopy is a powerful tool for the diagnosis of plasmas over a wide range of both temperature and density. However, such a measurement is often limited to probing plasmas with temperatures well below that of the x-ray source in order to avoid object plasma emission lines from obscuring important features of the absorption spectrum. This has excluded many plasmas from being investigated by this technique. We have developed an x-ray spectrometer that provides the ability to record absorption spectra from higher temperature plasmas than the usual approach allows without the risk of data contamination by line radiation emitted by the plasma under study. This is accomplished using a doubly curved mica crystal which is bent both elliptically and cylindrically. We present here the foundational work in the design and development of this spectrometer along with initial results obtained with an aluminum x-pinch as the object plasma.

  18. Proceedings of the eighth international colloquium on ultraviolet and x-ray spectroscopy of astrophysical and laboratory plasmas (IAU colloquium 86)

    SciTech Connect (OSTI)

    Not Available

    1984-01-01

    This volume represents the Proceedings of the Eighth International Colloquium on Ultraviolet and X-Ray Spectroscopy of Astrophysical and Laboratory Plasmas. The aim of this series of colloquia has been to bring together workers in the fields of astrophysical spectroscopy, laboratory spectroscopy and atomic physics in order to exchange ideas and results on problems which are common to these different disciplines. In addition to the presented papers there was a poster paper session. (WRF)

  19. Atomic memory access hardware implementations

    SciTech Connect (OSTI)

    Ahn, Jung Ho; Erez, Mattan; Dally, William J

    2015-02-17

    Atomic memory access requests are handled using a variety of systems and methods. According to one example method, a data-processing circuit having an address-request generator that issues requests to a common memory implements a method of processing the requests using a memory-access intervention circuit coupled between the generator and the common memory. The method identifies a current atomic-memory access request from a plurality of memory access requests. A data set is stored that corresponds to the current atomic-memory access request in a data storage circuit within the intervention circuit. It is determined whether the current atomic-memory access request corresponds to at least one previously-stored atomic-memory access request. In response to determining correspondence, the current request is implemented by retrieving data from the common memory. The data is modified in response to the current request and at least one other access request in the memory-access intervention circuit.

  20. Atomizing, continuous, water monitoring module

    DOE Patents [OSTI]

    Thompson, C.V.; Wise, M.B.

    1997-07-08

    A system for continuously analyzing volatile constituents of a liquid is described. The system contains a pump for continuously pumping the liquid to be tested at a predetermined flow rate into an extracting container through a liquid directing tube having an orifice at one end and positioned to direct the liquid into the extracting container at a flow rate sufficient to atomize the liquid within the extracting container. A continuous supply of helium carrier gas at a predetermined flow rate is directed through a tube into the extracting container and co-mingled with the atomized liquid to extract the volatile constituents contained within the atomized liquid. The helium containing the extracted volatile constituents flows out of the extracting container into a mass spectrometer for an analysis of the volatile constituents of the liquid. 3 figs.

  1. Atomizing, continuous, water monitoring module

    DOE Patents [OSTI]

    Thompson, Cyril V.; Wise, Marcus B.

    1997-01-01

    A system for continuously analyzing volatile constituents of a liquid is described. The system contains a pump for continuously pumping the liquid to be tested at a predetermined flow rate into an extracting container through a liquid directing tube having an orifice at one end and positioned to direct the liquid into the extracting container at a flow rate sufficient to atomize the liquid within the extracting container. A continuous supply of helium carrier gas at a predetermined flow rate is directed through a tube into the extracting container and co-mingled with the atomized liquid to extract the volatile constituents contained within the atomized liquid. The helium containing the extracted volatile constituents flows out of the extracting container into a mass spectrometer for an analysis of the volatile constituents of the liquid.

  2. Hot atom chemistry and radiopharmaceuticals

    SciTech Connect (OSTI)

    Krohn, Kenneth A.; Moerlein, Stephen M.; Link, Jeanne M.; Welch, Michael J.

    2012-12-19

    The chemical products made in a cyclotron target are a combined result of the chemical effects of the nuclear transformation that made the radioactive atom and the bulk radiolysis in the target. This review uses some well-known examples to understand how hot atom chemistry explains the primary products from a nuclear reaction and then how radiation chemistry is exploited to set up the optimal product for radiosynthesis. It also addresses the chemical effects of nuclear decay. There are important principles that are common to hot atom chemistry and radiopharmaceutical chemistry. Both emphasize short-lived radionuclides and manipulation of high specific activity nuclides. Furthermore, they both rely on radiochromatographic separation for identification of no-carrieradded products.

  3. ISMabs: A COMPREHENSIVE X-RAY ABSORPTION MODEL FOR THE INTERSTELLAR MEDIUM

    SciTech Connect (OSTI)

    Gatuzz, E.; Mendoza, C.; García, J.; Kallman, T. R.; Gorczyca, T. W. E-mail: claudio@ivic.gob.ve E-mail: timothy.r.kallman@nasa.gov

    2015-02-10

    We present an X-ray absorption model for the interstellar medium, to be referred to as ISMabs, that takes into account both neutral and ionized species of cosmically abundant elements, and includes the most accurate atomic data available. Using high-resolution spectra from eight X-ray binaries obtained with the Chandra High Energy Transmission Grating Spectrometer, we proceed to benchmark the atomic data in the model particularly in the neon K-edge region. Compared with previous photoabsorption models, which solely rely on neutral species, the inclusion of ions leads to improved spectral fits. Fit parameters comprise the column densities of abundant contributors that allow direct estimates of the ionization states. ISMabs is provided in the appropriate format to be implemented in widely used X-ray spectral fitting packages such as XSPEC, ISIS, and SHERPA.

  4. SMB, X-ray Emission Spectroscopy

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

    include X-ray Emission Spectroscopy (XES), Resonant Inelastic X-ray Scattering (RIXS), High Energy Resolution Fluorescence Detection (HERFD) and X-ray Raman Spectroscopy (XRS). ...

  5. Laser Induced Spectroscopy - Energy Innovation Portal

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

    Laser Induced Spectroscopy Idaho National Laboratory Contact INL About This Technology Technology Marketing Summary INL's Laser Induced Spectroscopy technology detects and measures ...

  6. Experimental estimation of oxidation-induced Si atoms emission on Si(001) surfaces

    SciTech Connect (OSTI)

    Ogawa, Shuichi Tang, Jiayi; Takakuwa, Yuji

    2015-08-15

    Kinetics of Si atoms emission during the oxidation of Si(001) surfaces have been investigated using reflection high energy electron diffraction combined with Auger electron spectroscopy. The area ratio of the 1 × 2 and the 2 × 1 domains on a clean Si(001) surface changed with the oxidation of the surface by Langmuir-type adsorption. This change in the domain ratio is attributed to the emission of Si atoms. We can describe the changes in the domain ratio using the Si emission kinetics model, which states that (1) the emission rate is proportional to the oxide coverage, and (2) the emitted Si atoms migrate on the surface and are trapped at S{sub B} steps. Based on our model, we find experimentally that up to 0.4 ML of Si atoms are emitted during the oxidation of a Si(001) surface at 576 °C.

  7. Absorption of Thermal Neutrons in Uranium

    DOE R&D Accomplishments [OSTI]

    Creutz, E. C.; Wilson, R. R.; Wigner, E. P.

    1941-09-26

    A knowledge of the absorption processes for neutrons in uranium is important for planning a chain reaction experiment. The absorption of thermal neutrons in uranium and uranium oxide has been studied. Neutrons from the cyclotron were slowed down by passage through a graphite block. A uranium or uranium oxide sphere was placed at various positions in the block. The neutron intensity at different points in the sphere and in the graphite was measured by observing the activity induced in detectors or uranium oxide or manganese. It was found that both the fission activity in the uranium oxide and the activity induced in manganese was affected by non-thermal neutrons. An experimental correction for such effects was made by making measurements with the detectors surrounded by cadmium. After such corrections the results from three methods of procedure with the uranium oxide detectors and from the manganese detectors were consistent to within a few per cent.

  8. Polaron absorption in amorphous tungsten oxide films

    SciTech Connect (OSTI)

    Berggren, Lars; Azens, Andris; Niklasson, Gunnar A.

    2001-08-15

    Amorphous thin films of tungsten oxide were deposited by sputtering onto glass substrates covered by conductive indium--tin oxide. The density and stoichiometry were determined by Rutherford backscattering spectrometry. Lithium ions were intercalated electrochemically into the films. The optical reflectance and transmittance were measured in the wavelength range from 0.3 to 2.5 {mu}m, at a number of intercalation levels. The polaron absorption peak becomes more symmetric and shifts to higher energies until an intercalation level of 0.25 to 0.3 Li{sup +}/W, where a saturation occurs. The shape of the polaron peak is in very good agreement with the theory of Bryksin [Fiz. Tverd. Tela 24, 1110 (1982)]. Within this model, the shift of the absorption peak is interpreted as an increase in the Fermi level of the material as more Li ions are inserted. {copyright} 2001 American Institute of Physics.

  9. Integrated vacuum absorption steam cycle gas separation

    SciTech Connect (OSTI)

    Chen, Shiaguo; Lu, Yonggi; Rostam-Abadi, Massoud

    2011-11-22

    Methods and systems for separating a targeted gas from a gas stream emitted from a power plant. The gas stream is brought into contact with an absorption solution to preferentially absorb the targeted gas to be separated from the gas stream so that an absorbed gas is present within the absorption solution. This provides a gas-rich solution, which is introduced into a stripper. Low pressure exhaust steam from a low pressure steam turbine of the power plant is injected into the stripper with the gas-rich solution. The absorbed gas from the gas-rich solution is stripped in the stripper using the injected low pressure steam to provide a gas stream containing the targeted gas. The stripper is at or near vacuum. Water vapor in a gas stream from the stripper is condensed in a condenser operating at a pressure lower than the stripper to concentrate the targeted gas. Condensed water is separated from the concentrated targeted gas.

  10. Laser-induced breakdown spectroscopy of alcohols and protein solutions

    SciTech Connect (OSTI)

    Melikechi, N.; Ding, H.; Marcano, O. A.; Rock, S.

    2008-04-15

    We report on the use of laser-induced breakdown spectroscopy for the study of organic samples that exhibit similar elemental composition. We evaluate the method for its potential application for the measurement of small spectroscopic differences between samples such as alcohols and water solution of proteins. We measure differences in the relative amplitudes of the oxygen peaks for alcohols and find that these correlate with the relative amount of oxygen atoms within the molecule. We also show that the spectra of proteins reveal differences that can be used for their detection and identification.

  11. Light absorption and electrical transport in Si:O alloys for photovoltaics

    SciTech Connect (OSTI)

    Mirabella, S.; Crupi, I.; Miritello, M.; Simone, F.; Di Martino, G.; Di Stefano, M. A.; Di Marco, S.; Priolo, F.

    2010-11-15

    Thin films (100-500 nm) of the Si:O alloy have been systematically characterized in the optical absorption and electrical transport behavior, by varying the Si content from 43 up to 100 at. %. Magnetron sputtering or plasma enhanced chemical vapor deposition have been used for the Si:O alloy deposition, followed by annealing up to 1250 deg. C. Boron implantation (30 keV, 3-30x10{sup 14} B/cm{sup 2}) on selected samples was performed to vary the electrical sheet resistance measured by the four-point collinear probe method. Transmittance and reflectance spectra have been extracted and combined to estimate the absorption spectra and the optical band gap, by means of the Tauc analysis. Raman spectroscopy was also employed to follow the amorphous-crystalline (a-c) transition of the Si domains contained in the Si:O films. The optical absorption and the electrical transport of Si:O films can be continuously and independently modulated by acting on different parameters. The light absorption increases (by one decade) with the Si content in the 43-100 at. % range, determining an optical band gap which can be continuously modulated into the 2.6-1.6 eV range, respectively. The a-c phase transition in Si:O films, causing a significant reduction in the absorption coefficient, occurs at increasing temperatures (from 600 to 1100 deg. C) as the Si content decreases. The electrical resistivity of Si:O films can be varied among five decades, being essentially dominated by the number of Si grains and by the doping. Si:O alloys with Si content in the 60-90 at. % range (named oxygen rich silicon films), are proved to join an appealing optical gap with a viable conductivity, being a good candidate for increasing the conversion efficiency of thin-film photovoltaic cell.

  12. Particle Soot Absorption Photometer Instrument Handbook

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

    6 Particle Soot Absorption Photometer Handbook SR Springston March 2016 DISCLAIMER This report was prepared as an account of work sponsored by the U.S. Government. Neither the United States nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned

  13. A New Model for Liquid Water Absorption

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

    Model for Liquid Water Absorption For original submission and image(s), see ARM Research Highlights http://www.arm.gov/science/highlights/ Research Highlight Liquid water path (LWP) is a critical measurement for a wide range of atmospheric studies, as the amount of liquid in a cloud is critical to understanding many cloud processes. For example, the radiative impact of the cloud (in both the longwave and shortwave portions of the spectrum) depends heavily on the LWP. Thus, the Atmospheric

  14. Radiation absorption properties of different plaster samples

    SciTech Connect (OSTI)

    Akkurt, Iskender; Guenoglu, Kadir; Mavi, Betuel; K Latin-Small-Letter-Dotless-I l Latin-Small-Letter-Dotless-I ncarslan, Semsettin; Seven, Aysun

    2012-09-06

    Although the plaster is one of the oldest known synthetic building materials, nowadays, it is used as interior coating of walls and ceilings of buildings. Thus measuring its radiation shielding properties is vital. For this purpose, radiation absorption properties of different plaster samples in this study. The measurements have been performed using gamma spectrometer system which connected to 3'' Multiplication-Sign 3''NaI (TI) detector.

  15. Ring resonant cavities for spectroscopy

    DOE Patents [OSTI]

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

    1999-06-15

    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.

  16. Ring resonant cavities for spectroscopy

    DOE Patents [OSTI]

    Zare, Richard N.; Martin, Juergen; Paldus, Barbara A.; Xie, Jinchun

    1999-01-01

    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).

  17. Possible Demonstration of a Polaronic Bose-Einstein(-Mott) Condensate in UO2(+x) by Ultrafast THz Spectroscopy and Microwave Dissipation

    SciTech Connect (OSTI)

    Conradson, Steven D.; Gilbertson, Steven M.; Daifuku, Stephanie L.; Kehl, Jeffrey A.; Durakiewicz, Tomasz; Andersson, David A.; Bishop, Alan R.; Byler, Darrin D.; Maldonado, Pablo; Oppeneer, Peter M.; Valdez, James A.; Neidig, Michael L.; Rodriguez, George

    2015-10-16

    Bose-Einstein condensates (BECs) composed of polarons would be an advance because they would combine coherently charge, spin, and a crystal lattice. Following our earlier report of unique structural and spectroscopic properties, we now identify potentially definitive evidence for polaronic BECs in photo- and chemically doped UO2(+x) on the basis of exceptional coherence in the ultrafast time dependent terahertz absorption and microwave spectroscopy results that show collective behavior including dissipation patterns whose precedents are condensate vortex and defect disorder and condensate excitations. Furthermore, that some of these signatures of coherence in an atom-based system extend to ambient temperature suggests a novel mechanism that could be a synchronized, dynamical, disproportionation excitation, possibly via the solid state analog of a Feshbach resonance that promotes the coherence. Such a mechanism would demonstrate that the use of ultra-low temperatures to establish the BEC energy distribution is a convenience rather than a necessity, with the actual requirement for the particles being in the same state that is not necessarily the ground state attainable by other means. Interestingly, a macroscopic quantum object created by chemical doping that can persist to ambient temperature and resides in a bulk solid would be revolutionary in a number of scientific and technological fields.

  18. Possible Demonstration of a Polaronic Bose-Einstein(-Mott) Condensate in UO2(+x) by Ultrafast THz Spectroscopy and Microwave Dissipation

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

    Conradson, Steven D.; Gilbertson, Steven M.; Daifuku, Stephanie L.; Kehl, Jeffrey A.; Durakiewicz, Tomasz; Andersson, David A.; Bishop, Alan R.; Byler, Darrin D.; Maldonado, Pablo; Oppeneer, Peter M.; et al

    2015-10-16

    Bose-Einstein condensates (BECs) composed of polarons would be an advance because they would combine coherently charge, spin, and a crystal lattice. Following our earlier report of unique structural and spectroscopic properties, we now identify potentially definitive evidence for polaronic BECs in photo- and chemically doped UO2(+x) on the basis of exceptional coherence in the ultrafast time dependent terahertz absorption and microwave spectroscopy results that show collective behavior including dissipation patterns whose precedents are condensate vortex and defect disorder and condensate excitations. Furthermore, that some of these signatures of coherence in an atom-based system extend to ambient temperature suggests a novelmore » mechanism that could be a synchronized, dynamical, disproportionation excitation, possibly via the solid state analog of a Feshbach resonance that promotes the coherence. Such a mechanism would demonstrate that the use of ultra-low temperatures to establish the BEC energy distribution is a convenience rather than a necessity, with the actual requirement for the particles being in the same state that is not necessarily the ground state attainable by other means. Interestingly, a macroscopic quantum object created by chemical doping that can persist to ambient temperature and resides in a bulk solid would be revolutionary in a number of scientific and technological fields.« less

  19. Possible Demonstration of a Polaronic Bose-Einstein(-Mott) Condensate in UO2(+x) by Ultrafast THz Spectroscopy and Microwave Dissipation

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

    Conradson, Steven D.; Gilbertson, Steven M.; Daifuku, Stephanie L.; Kehl, Jeffrey A.; Durakiewicz, Tomasz; Andersson, David A.; Bishop, Alan R.; Byler, Darrin D.; Maldonado, Pablo; Oppeneer, Peter M.; et al

    2015-10-16

    Bose-Einstein condensates (BECs) composed of polarons would be an advance because they would combine coherently charge, spin, and a crystal lattice. Following our earlier report of unique structural and spectroscopic properties, we now identify potentially definitive evidence for polaronic BECs in photo- and chemically doped UO2(+x) on the basis of exceptional coherence in the ultrafast time dependent terahertz absorption and microwave spectroscopy results that show collective behavior including dissipation patterns whose precedents are condensate vortex and defect disorder and condensate excitations. Furthermore, that some of these signatures of coherence in an atom-based system extend to ambient temperature suggests a novelmore »mechanism that could be a synchronized, dynamical, disproportionation excitation, possibly via the solid state analog of a Feshbach resonance that promotes the coherence. Such a mechanism would demonstrate that the use of ultra-low temperatures to establish the BEC energy distribution is a convenience rather than a necessity, with the actual requirement for the particles being in the same state that is not necessarily the ground state attainable by other means. Interestingly, a macroscopic quantum object created by chemical doping that can persist to ambient temperature and resides in a bulk solid would be revolutionary in a number of scientific and technological fields.« less

  20. WATER-LITHIUM BROMIDE DOUBLE-EFFECT ABSORPTION COOLING ANALYSIS

    Office of Scientific and Technical Information (OSTI)

    WATER-LITHIUM BROMIDE DOUBLE-EFFECT ABSORPTION COOLING ANALYSIS Gary C . V l i e t , ... i e n t simulation of the double-effect, water-1 ithium bromide absorption cooling ...

  1. Triple effect absorption chiller utilizing two refrigeration circuits

    SciTech Connect (OSTI)

    DeVault, R.C.

    1988-03-22

    This patent describes a heat absorption method for an absorption chiller. It comprises: providing a firs absorption system circuit for operation within a first temperature range, providing a second absorption system circuit for operation within a second temperature range; heat exchanging refrigerant and absorber solution; thermal communication with an external heat load. This patent describes a heat absorption apparatus for use as an absorption chiller. It includes: a first absorption system circuit for operation within a first temperature range; a second absorption system circuit for operation within a second temperature range which has a lower maximum temperature relative to the first temperature range; the first circuit having generator means, condenser means, evaporator means, and absorber means operatively connected together; the second circuit having generator means condenser means, evaporator means, and absorber means operative connected together; and the first circuit condenser means and the first circuit absorber means being in heat exchange communication with the second circuit generator means.

  2. Effect of Various Impurities on the Hydrogen Absorption on SAES...

    Office of Environmental Management (EM)

    Effect of Various Impurities on the Hydrogen Absorption on SAES ST198 Effect of Various Impurities on the Hydrogen Absorption on SAES ST198 Presentation from the 36th Tritium Focus ...

  3. CO2 CAPTURE BY ABSORPTION WITH POTASSIUM CARBONATE (Technical...

    Office of Scientific and Technical Information (OSTI)

    Subject: 54 ENVIRONMENTAL SCIENCES; CARBON DIOXIDE; ABSORPTION; SORPTIVE PROPERTIES; POTASSIUM CARBONATES; THERMODYNAMIC MODEL; VAPOR PRESSURE; AIR POLLUTION CONTROL Word Cloud ...

  4. CO2 Capture by Absorption with Potassium Carbonate (Technical...

    Office of Scientific and Technical Information (OSTI)

    ... Subject: 54 ENVIRONMENTAL SCIENCES; CARBON DIOXIDE; ABSORPTION; POTASSIUM CARBONATES; SORPTIVE PROPERTIES; AMINES; MATERIALS RECOVERY; AIR POLLUTION CONTROL; MATHEMATICAL MODELS ...

  5. CO2 CAPTURE BY ABSORPTION WITH POTASSIUM CARBONATE (Technical...

    Office of Scientific and Technical Information (OSTI)

    Subject: 54 ENVIRONMENTAL SCIENCES; ABSORPTION; HEAT EXCHANGERS; PILOT PLANTS; POTASSIUM CARBONATES; THERMODYNAMICS; VAPOR PRESSURE; CARBON DIOXIDE; AIR POLLUTION CONTROL; SORPTIVE ...

  6. Split-flow regeneration in absorptive air separation

    DOE Patents [OSTI]

    Weimer, R.F.

    1987-11-24

    A chemical absorptive separation of air in multiple stage of absorption and desorption is performed with partial recycle of absorbent between stages of desorption necessary to match equilibrium conditions in the various stages of absorption. This allows reduced absorbent flow, reduced energy demand and reduced capital costs. 4 figs.

  7. Split-flow regeneration in absorptive air separation

    DOE Patents [OSTI]

    Weimer, Robert F.

    1987-01-01

    A chemical absorptive separation of air in multiple stage of absorption and desorption is performed with partial recycle of absorbent between stages of desorption necessary to match equilibrium conditions in the various stages of absorption. This allows reduced absorbent flow, reduced energy demand and reduced capital costs.

  8. Displacement per Atom, Primary Knocked-on Atoms Produced in an Atomic Solid Target

    Energy Science and Technology Software Center (OSTI)

    2015-07-01

    Version 00 DART calculates the total number of displacements, primary knocked-on atoms, recoil spectra, displacement cross sections and displacement per atoms rates in a poly atomic solid target, composed of many different isotopes, using ENDF/B-VI derived cross sections. To calculate these values, different incident particles were considered: neutrons, ions and electrons. The user needs only to specify an incident particle energy spectrum and the composition of the target. The number of displaced atoms is calculatedmore » within the Binary Collision Approximation framework. To calculate the number of displacements the DART code does not use the classical NRT dpa analytical formula, which is only appropriate for projectile and target of the same mass. It numerically solves the linearized Boltzmann equation for a polyatomic target. It can be a useful tool to select the nature and energy of ions or electrons in particle accelerators or electron microscopes to mimic the primary damage induced by neutron irradiation in nuclear plants or fission facilities. Nuclear data: • Typically any ENDFB format evaluation may be used. This package includes the ENDFB-VI nuclear data library. Energy ranges: • Neutron or ion : 10E-11 to 20 MeV Data library distributed with DART v1.0: • ENDFB-VI nuclear data library« less

  9. GAS AND DUST ABSORPTION IN THE DoAr 24E SYSTEM

    SciTech Connect (OSTI)

    Kruger, Andrew J.; Richter, Matthew J.; Seifahrt, Andreas; Carr, John S.; Najita, Joan R.; Moerchen, Margaret M.; Doppmann, Greg W.

    2012-11-20

    We present findings for DoAr 24E, a binary system that includes a classical infrared companion. We observed the DoAr 24E system with the Spitzer Infrared Spectrograph (IRS), with high-resolution, near-infrared spectroscopy of CO vibrational transitions, and with mid-infrared imaging. The source of high extinction toward infrared companions has been an item of continuing interest. Here we investigate the disk structure of DoAr 24E using the column densities, temperature, and velocity profiles of two CO absorption features seen toward DoAr 24Eb. We model the spectral energy distributions found using T-ReCS imaging and investigate the likely sources of extinction toward DoAr 24Eb. We find the lack of silicate absorption and small CO column density toward DoAr 24Eb suggest that the mid-infrared continuum is not as extinguished as the near-infrared, possibly due to the mid-infrared originating from an extended region. This, along with the velocity profile of the CO absorption, suggests that the source of high extinction is likely due to a disk or disk wind associated with DoAr 24Eb.

  10. TIME-RESOLVED VIBRATIONAL SPECTROSCOPY

    SciTech Connect (OSTI)

    Andrei Tokmakoff, MIT; Paul Champion, Northeastern University; Edwin J. Heilweil, NIST; Keith A. Nelson, MIT; Larry Ziegler, Boston University

    2009-05-14

    This document contains the Proceedings from the 14th International Conference on Time-Resolved Vibrational Spectroscopy, which was held in Meredith, NH from May 9-14, 2009. The study of molecular dynamics in chemical reaction and biological processes using time-resolved spectroscopy plays an important role in our understanding of energy conversion, storage, and utilization problems. Fundamental studies of chemical reactivity, molecular rearrangements, and charge transport are broadly supported by the DOE’s Office of Science because of their role in the development of alternative energy sources, the understanding of biological energy conversion processes, the efficient utilization of existing energy resources, and the mitigation of reactive intermediates in radiation chemistry. In addition, time-resolved spectroscopy is central to all five of DOE’s grand challenges for fundamental energy science. The Time-Resolved Vibrational Spectroscopy conference is organized biennially to bring the leaders in this field from around the globe together with young scientists to discuss the most recent scientific and technological advances. The latest technology in ultrafast infrared, Raman, and terahertz spectroscopy and the scientific advances that these methods enable were covered. Particular emphasis was placed on new experimental methods used to probe molecular dynamics in liquids, solids, interfaces, nanostructured materials, and biomolecules.

  11. Thermal model of solar absorption HVAC systems

    SciTech Connect (OSTI)

    Bergquam, J.B.; Brezner, J.M.

    1995-11-01

    This paper presents a thermal model that describes the performance of solar absorption HVAC systems. The model considers the collector array, the building cooling and heating loads, the absorption chiller and the high temperature storage. Heat losses from the storage tank and piping are included in the model. All of the results presented in the paper are for an array of flat plate solar collectors with black chrome (selective surface) absorber plates. The collector efficiency equation is used to calculate the useful heat output from the array. The storage is modeled as a non-stratified tank with polyurethane foam insulation. The system is assumed to operate continuously providing air conditioning during the cooling season, space heating during the winter and hot water throughout the year. The amount of heat required to drive the chiller is determined from the coefficient of performance of the absorption cycle. Results are presented for a typical COP of 0.7. The cooling capacity of the chiller is a function of storage (generator) temperature. The nominal value is 190 F (88 C) and the range of values considered is 180 F (82 C) to 210 F (99 C). Typical building cooling and heating loads are determined as a function of ambient conditions. Performance results are presented for Sacramento, CA and Washington, D.C. The model described in the paper makes use of National Solar Radiation Data Base (NSRDB) data and results are presented for these two locations. The uncertainties in the NSRDB are estimated to be in a range of 6% to 9%. This is a significant improvement over previously available data. The model makes it possible to predict the performance of solar HVAC systems and calculate quantities such as solar fraction, storage temperature, heat losses and parasitic power for every hour of the period for which data are available.

  12. Laser dynamics with excited-state absorption

    SciTech Connect (OSTI)

    Sanchez, F.; Kellou, A.

    1997-01-01

    The dynamics of a laser with excited-state absorption at the lasing wavelength is theoretically studied. The model is based on the rate equations for a four-level system. The stationary state is analytically calculated, permitting both the investigation of the laser characteristics and linear stability analysis. The latter shows that, in some conditions, the steady state is not stable in a particular range of pumping rates. However, a stable solution is restored for sufficiently high pumping rates. Stable self-pulsing solutions are obtained by numerical integration of the coupled equations. Also, the transient regimes are numerically analyzed. {copyright} 1997 Optical Society of America.

  13. Distributed Bragg Reflectors With Reduced Optical Absorption

    DOE Patents [OSTI]

    Klem, John F.

    2005-08-16

    A new class of distributed Bragg reflectors has been developed. These distributed Bragg reflectors comprise interlayers positioned between sets of high-index and low-index quarter-wave plates. The presence of these interlayers is to reduce photon absorption resulting from spatially indirect photon-assisted electronic transitions between the high-index and low-index quarter wave plates. The distributed Bragg reflectors have applications for use in vertical-cavity surface-emitting lasers for use at 1.55 .mu.m and at other wavelengths of interest.

  14. Optofluidic-Tunable Color Filters And Spectroscopy Based On Liquid-Crystal Microflows

    SciTech Connect (OSTI)

    Cuennet, J. G.; Vasdekis, Andreas E.; Psaltis, D.

    2013-05-24

    The integration of color filters with microfluidics has attracted substantial attention in recent years, for on-chip absorption, fluorescence, or Raman analysis. We describe such tunable filters based on the micro-flow of liquid crystals. The filter operation is based on the wavelength dependent liquid crystal birefringence that can be tuned by modifying the flow velocity field in the microchannel. The latter is possible both temporally and spatially by varying the inlet pressure and the channel geometry respectively. We explored the use of these optofluidic filters for on-chip absorption spectroscopy; by integrating the distance dependent color filter with a dye-filled micro-channel, the absorption spectrum of a dye could be measured. Liquid crystal microflows simplify substantially the optofluidic integration, actuation and tuning of color filters for lab-on-a-chip spectroscopic applications.

  15. Atomic vapor laser isotope separation

    SciTech Connect (OSTI)

    Stern, R.C.; Paisner, J.A.

    1985-11-08

    Atomic vapor laser isotope separation (AVLIS) is a general and powerful technique. A major present application to the enrichment of uranium for light-water power reactor fuel has been under development for over 10 years. In June 1985 the Department of Energy announced the selection of AVLIS as the technology to meet the nation's future need for the internationally competitive production of uranium separative work. The economic basis for this decision is considered, with an indicated of the constraints placed on the process figures of merit and the process laser system. We then trace an atom through a generic AVLIS separator and give examples of the physical steps encountered, the models used to describe the process physics, the fundamental parameters involved, and the role of diagnostic laser measurements.

  16. The Modified Embedded Atom Method

    SciTech Connect (OSTI)

    Baskes, M.I.

    1994-08-01

    Recent modifications have been made to generalize the Embedded Atom Method (EAM) to describe bonding in diverse materials. By including angular dependence of the electron density in an empirical way, the Modified Embedded Atom Method (MEAM) has been able to reproduce the basic energetic and structural properties of 45 elements. This method is ideally suited for examining the interfacial behavior of dissimilar materials. This paper explains in detail the derivation of the method, shows how the parameters of the MEAM are determined directly from experiment or first principles calculations, and examines the quality of the reproduction of the database. Materials with fcc, bcc, hcp, and diamond cubic crystal structure are discussed. A few simple examples of the application of the MEAM to surfaces and interfaces are presented. Calculations of pullout of a SiC fiber in a diamond matrix as a function of applied stress show non-uniform deformation of the fiber.

  17. Improved self-absorption correction for extended x-ray absorption fine-structure measurements

    SciTech Connect (OSTI)

    Booth, C.H.; Bridges, F.

    2003-06-04

    Extended x-ray absorption fine-structure (EXAFS) data collected in the fluorescence mode are susceptible to an apparent amplitude reduction due to the self-absorption of the fluorescing photon by the sample before it reaches a detector. Previous treatments have made the simplifying assumption that the effect of the EXAFS on the correction term is negligible, and that the samples are in the thick limit. We present a nearly exact treatment that can be applied for any sample thickness or concentration, and retains the EXAFS oscillations in the correction term.

  18. The Future of Atomic Energy

    DOE R&D Accomplishments [OSTI]

    Fermi, E.

    1946-05-27

    There is definitely a technical possibility that atomic power may gradually develop into one of the principal sources of useful power. If this expectation will prove correct, great advantages can be expected to come from the fact that the weight of the fuel is almost negligible. This feature may be particularly valuable for making power available to regions of difficult access and far from deposits of coal. It also may prove a great asset in mobile power units for example in a power plant for ship propulsion. On the negative side there are some technical limitations to be applicability of atomic power of which perhaps the most serious is the impossibility of constructing light power units; also there will be some peculiar difficulties in operating atomic plants, as for example the necessity of handling highly radioactive substances which will necessitate, at least for some considerable period, the use of specially skilled personnel for the operation. But the chief obstacle in the way of developing atomic power will be the difficulty of organizing a large scale industrial development in an internationally safe way. This presents actually problems much more difficult to solve than any of the technical developments that are necessary, It will require an unusual amount of statesmanship to balance properly the necessity of allaying the international suspicion that arises from withholding technical secrets against the obvious danger of dumping the details of the procedures for an extremely dangerous new method of warfare on a world that may not yet be prepared to renounce war. Furthermore, the proper balance should be found in the relatively short time that will elapse before the 'secrets' will naturally become open knowledge by rediscovery on part of the scientists and engineers of other countries.

  19. Ultrafast recovery time and broadband saturable absorption properties of black phosphorus suspension

    SciTech Connect (OSTI)

    Wang, Yingwei; Huang, Guanghui; Chen, Jiazhang; Xiao, Si He, Jun; Mu, Haoran; Bao, Qiaoliang; Lin, Shenghuang

    2015-08-31

    As a new type of two-dimensional crystal material, black phosphorus (BP) exhibits excellent electronics and optical performance. Herein, we focus on carrier relaxation dynamics and nonlinear optical properties of BP suspension. Atomic force microscopy, transmission electron microscopy, and optical transmission spectrum are employed to characterize the structure and linear optical properties of the BP. Additionally, pump-probe experiments at wavelength of 1550 nm were carried out to study the carrier dynamics in BP suspension, and ultrafast recovery time was observed (τ{sub s} = 24 ± 2 fs). Furthermore, we demonstrate the saturable absorption signals by open aperture Z-scan experiments at wavelengths of 1550 nm, 532 nm, and 680 nm. The results indicate that BP has broadband saturable absorption properties and the nonlinear absorption coefficients were determined to be β{sub 2} = −0.20 ± 0.08 × 10{sup −3 }cm/GW (532 nm), β{sub 2} = −0.12 ± 0.05 × 10{sup −3 }cm/GW (680 nm), and β{sub 2} = −0.15 ± 0.09 × 10{sup −3 }cm/GW (1550 nm)

  20. Dilution cycle control for an absorption refrigeration system

    DOE Patents [OSTI]

    Reimann, Robert C.

    1984-01-01

    A dilution cycle control system for an absorption refrigeration system is disclosed. The control system includes a time delay relay for sensing shutdown of the absorption refrigeration system and for generating a control signal only after expiration of a preselected time period measured from the sensed shutdown of the absorption refrigeration system, during which the absorption refrigeration system is not restarted. A dilution cycle for the absorption refrigeration system is initiated in response to generation of a control signal by the time delay relay. This control system is particularly suitable for use with an absorption refrigeration system which is frequently cycled on and off since the time delay provided by the control system prevents needless dilution of the absorption refrigeration system when the system is turned off for only a short period of time and then is turned back on.

  1. Complexes of self-interstitials with oxygen atoms in Ge

    SciTech Connect (OSTI)

    Khirunenko, L. I.; Pomozov, Yu. V.; Sosnin, M. G.; Abrosimov, N. V.; Riemann, H.

    2014-02-21

    Interactions of germanium self-interstitials with interstitial oxygen atoms in Ge subjected to irradiation at ?80 K and subsequently to annealing have been studied. To distinguish the processes involving vacancies and self-interstitials the doping with tin was used. It was shown that absorption lines with maximum at 602, 674, 713 and 803 cm{sup ?1} are self-interstitials-related. Two lines at 602 and 674, which develop upon annealing in the temperature range 180240 K, belong to IO complexes, while the bands at 713 and 803 cm{sup ?1}, which emerge after annealing at T>220 K, are associated with I{sub 2}O. It is argued that the annealing of IO occurs by two mechanisms: by dissociation and by diffusion.

  2. Princeton Plasma Physics Lab - General Atomics (GA)

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

    general-atomics-ga General Atomics en The Scorpion's Strategy: "Catch and Subdue" http:www.pppl.govnode1132

  3. Absorption of solar radiation in broken clouds

    SciTech Connect (OSTI)

    Zuev, V.E.; Titov, G.A.; Zhuravleva, T.B.

    1996-04-01

    It is recognized now that the plane-parallel model unsatisfactorily describes the transfer of radiation through broken clouds and that, consequently, the radiation codes of general circulation models (GCMs) must be refined. However, before any refinement in a GCM code is made, it is necessary to investigate the dependence of radiative characteristics on the effects caused by the random geometry of cloud fields. Such studies for mean fluxes of downwelling and upwelling solar radiation in the visible and near-infrared (IR) spectral range were performed by Zuev et al. In this work, we investigate the mean spectral and integrated absorption of solar radiation by broken clouds (in what follows, the term {open_quotes}mean{close_quotes} will be implied but not used, for convenience). To evaluate the potential effect of stochastic geometry, we will compare the absorption by cumulus (0.5 {le} {gamma} {le} 2) to that by equivalent stratus ({gamma} <<1) clouds; here {gamma} = H/D, H is the cloud layer thickness and D the characteristic horizontal cloud size. The equivalent stratus clouds differ from cumulus only in the aspect ratio {gamma}, all the other parameters coinciding.

  4. Residential solar-absorption chiller thermal dynamics

    SciTech Connect (OSTI)

    Guertin, J.M.; Wood, B.D.; McNeill, B.W.

    1981-03-01

    Research is reported on the transient performance of a commercial residential 3 ton lithium bromide-water absorption chiller designed for solar firing. Emphasis was placed on separating the chiller response from that of the entire test facility so that its transient response could solely be observed and quantified. It was found that the entire system time response and thermal capacitance has a major impact on performance degradation due to transient operation. Tests run to ascertain computer algorithms which simulate system isolated chiller performance, revealed processes hitherto undocumented. Transient operation is simulated by three distinct algorithms associated with the three phases of chiller operation. The first phase is start up time. It was revealed during testing that the time required to reach steady state performance values, when the chiller was turned on, was a linear function of steady state water supply temperatures. The second phase is quasi steady state performance. Test facility's performance compared favorably with the manufacturer's published data. The third phase is the extra capacity produced during spin down. Spin down occurs when the hot water supply pump is turned off while the other system pumps remain operating for a few minutes, thus allowing extra chiller capacity to be realized. The computer algorithms were used to generate plots which show the operational surface of an isolated absorption chiller subjected to off design and transient operation.

  5. Solar absorption cooling plant in Seville

    SciTech Connect (OSTI)

    Bermejo, Pablo; Pino, Francisco Javier; Rosa, Felipe

    2010-08-15

    A solar/gas cooling plant at the Engineering School of Seville (Spain) was tested during the period 2008-2009. The system is composed of a double-effect LiBr + water absorption chiller of 174 kW nominal cooling capacity, powered by: (1) a pressurized hot water flow delivered by mean of a 352 m{sup 2} solar field of a linear concentrating Fresnel collector and (2) a direct-fired natural gas burner. The objective of the project is to indentify design improvements for future plants and to serve as a guideline. We focused our attention on the solar collector size and dirtiness, climatology, piping heat losses, operation control and coupling between solar collector and chiller. The daily average Fresnel collector efficiency was 0.35 with a maximum of 0.4. The absorption chiller operated with a daily average coefficient of performance of 1.1-1.25, where the solar energy represented the 75% of generator's total heat input, and the solar cooling ratio (quotient between useful cooling and insolation incident on the solar field) was 0.44. (author)

  6. Hydroxide absorption heat pumps with spray absorber

    SciTech Connect (OSTI)

    Summerer, F.; Alefeld, G.; Zeigler, F.; Riesch, P.

    1996-11-01

    The absorber is one of the most expensive components of an absorption heat pump or chiller, respectively. In order to reduce the cost of a heat exchanger, much effort is invested into searching for additives for heat transfer enhancement. Another way to reduce heat exchanger cost, especially for machines with low capacities, is to use an adiabatic spray absorber. The basic principles of the spray absorber is to perform heat and mass transfer separated from each other in two different components. In this way the heat can be rejected effectively in a liquid-liquid heat exchanger, whereas the mass transfer occurs subsequently in a simple vessel. The spray technique can not only save heat exchanger cost in conventional absorption systems working with water and lithium bromide, it also allows the use of quite different working fluids such as hydroxides, which have lower heat transfer coefficients in falling films. Moreover, the separated heat transfer can easily be performed in a liquid-to-air heat exchanger. Hence it is obvious to use hydroxides that allow for a high temperature lift for building an air-cooled chiller with spray absorber. In this presentation theoretical and experimental investigations of the spray absorber as well as the setup will be described. Finally, possible applications will be outlined.

  7. The Atomic Energy Commission By Alice Buck

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

    Atomic Energy Commission By Alice Buck July 1983 U.S. Department of Energy Office of Management Office of the Executive Secretariat Office of History and Heritage Resources 1 Introduction Almost a year after World War II ended, Congress established the United States Atomic Energy Commission to foster and control the peacetime development of atomic science and technology. Reflecting America's postwar optimism, Congress declared that atomic energy should be employed not only in the Nation's

  8. How Atomic Vibrations Transform Vanadium Dioxide

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

    How Atomic Vibrations Transform Vanadium Dioxide How Atomic Vibrations Transform Vanadium Dioxide Calculations Confirm Material's Potential for Next-Generation Electronics, Energy November 10, 2014 Contact: Dawn Levy, levyd@ornl.gov, 865.576.6448 Budaivibe Vanadium atoms (blue) have unusually large thermal vibrations that stabilize the metallic state of a vanadium dioxide crystal. Red depicts oxygen atoms. Image credit: Oak Ridge National Laboratory For more than 50 years, scientists have

  9. Atomic-Resolution Spectroscopic Imaging and In Situ Environmental Study of

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

    Bimetallic Nanocatalysts by Fast Electrons | Stanford Synchrotron Radiation Lightsource Atomic-Resolution Spectroscopic Imaging and In Situ Environmental Study of Bimetallic Nanocatalysts by Fast Electrons Thursday, October 24, 2013 - 3:30pm SLAC, Conference Room 137-322 Presented by Huolin Xin Center for Functional Nanomaterials Brookhaven National Laboratory, Upton, New York Scanning transmission electron microscopy (STEM) in combination with electron energy loss spectroscopy (EELS) has

  10. Gauss Sum Factorization with Cold Atoms

    SciTech Connect (OSTI)

    Gilowski, M.; Wendrich, T.; Mueller, T.; Ertmer, W.; Rasel, E. M. [Institut fuer Quantenoptik, Leibniz Universitaet Hannover, Welfengarten 1, D-30167 Hannover (Germany); Jentsch, Ch. [Astrium GmbH-Satellites, 88039 Friedrichshafen (Germany); Schleich, W. P. [Institut fuer Quantenphysik, Universitaet Ulm, Albert-Einstein-Allee 11, D-89081 Ulm (Germany)

    2008-01-25

    We report the first implementation of a Gauss sum factorization algorithm by an internal state Ramsey interferometer using cold atoms. A sequence of appropriately designed light pulses interacts with an ensemble of cold rubidium atoms. The final population in the involved atomic levels determines a Gauss sum. With this technique we factor the number N=263193.

  11. Frequency Modulation Spectroscopy Modeling for Remote Chemical Detection

    SciTech Connect (OSTI)

    Sheen, David M.

    2000-09-30

    Frequency modulation (FM) spectroscopy techniques show promise for active infrared remote chemical sensing. FM spectroscopy techniques have reduced sensitivity to optical and electronic noise, and are relatively immune to the effects of various electronic and mechanical drifts. FM systems are responsive to sharp spectral features and can therefore reduce the effects of spectral clutter due to interfering chemicals in the plume or in the atmosphere. The relatively high modulation frequencies used for FM also reduces the effects of albedo (reflectance) and plume variations. Conventional differential absorption lidar (DIAL) systems are performance limited by the noise induced by speckle. Analysis presented in this report shows that FM based sensors may reduce the effects of speckle by one to two orders of magnitude. This can result in reduced dwell times and faster area searches, as well as reducing various forms of spatial clutter. FM systems will require a laser system that is continuously tunable at relatively high frequencies (0.1 to 20 MHz). One promising candidate is the quantum-cascade (QC) laser [1, 2]. The QC laser is potentially capable of power levels on the order of 1 Watt and frequency tuning on the order of 3 - 6 GHz, which is the performance level required for FM spectroscopy based remote sensing. In this report we describe a high-level numerical model for an FM spectroscopy based remote sensing system, and application to two unmanned airborne vehicle (UAV) scenarios. A Predator scenario operating at a slant range of 6.5 km with a 10 cm diameter telescope, and a Global Hawk scenario operating at a range of 30 km with a 20 cm diameter telescope, has been assumed to allow estimation of the performance of potential FM systems.

  12. Operation Sandstone. Scientific Director's report of atomic-weapon tests at Eniwetok, 1948. Annex 8. Gamma-ray measurements. Parts 1, 2, 3, 4, and 5. Sandstone report No. 29

    SciTech Connect (OSTI)

    Shonka, F.R.; Pawlicki, G.S.

    1985-09-01

    Curves of absorption of gamma rays in boron carbide and a few points on the absorption curve in lead were obtained during the three atomic explosions of Operation Sandstone. Radiation was detected by integrating ionization chambers and by photographic emulsions. A few recording-type ionization chambers were used to give intensities as a function of time. Radiation detectors were located inside of shelters which protected them from blast and shielded them from scattered radiation. Because of geometry, scattered radiation was negligible and the analysis of absorption curves yields the true total absorption coefficient for the radiation.

  13. Combined in Situ X-ray absorption and diffuse reflectance infraredspectroscopy: An attractive tool for catalytic investigations

    SciTech Connect (OSTI)

    Marinkovic, N.S.; Ehrlich, S.; Wang, Q.; Barrio, L.; Khalid, S.; et.al.

    2010-11-24

    Catalysis investigations are often followed in a range of spectroscopic techniques. While diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) can be done on a bench-top instrument, X-ray absorption spectroscopy (XAS) techniques, such as extended X-ray absorption fine structure (EXAFS) and X-ray absorption near-edge structure (XANES) require synchrotron light. In order to ensure the same conditions during in situ catalysis for each method, a combined XAS/DRIFTS has been developed at beamline X18A at the National Synchrotron Light Source, Brookhaven National Laboratory. A rapid-scan FTIR spectrometer capable of both mid- and far-infrared measurements is equipped with an arm to redirect the IR beam outside the spectrometer. An in situ reaction chamber, equipped with glassy carbon windows for X-ray light and a KBr window for IR light passage is installed firmly on the arm. The reaction cell can be heated to 600 C and allows passage of gases through the catalyst so that both XAS and DRIFTS techniques can be done simultaneously in controlled environment conditions. Together with a fast-moving monochromator for quick-EXAFS and mass-spectrometric residual gas analysis, this new tool is a powerful method for testing catalytic reactions in real time.

  14. Impurity detection in the APEX tokamak by in-situ doppler shift laser fluorescence spectroscopy

    SciTech Connect (OSTI)

    Pellin, M.J.; Young, C.E.; Gruen, D.M.; Norem, J.H.

    1981-01-01

    Laser fluorescence spectroscopy (LFS) is a promising impurity atoms generated from surfaces exposed to fusion plasmas. Here the first continuous wave laser fluorescene measurement of impurities generated during a single tokamak pulse is reported. The results point out the promise of LFS as an essentially real time, in-situ diagnostic allowing a detailed comparison of impurity generation and transport with Tokamak parameters and operating conditions. Results presented will include the Zr-atom density and velocity distribution produced from a Zr-metal target during an Apex Tokamak discharge.

  15. Analytical Spectroscopy - Energy Innovation Portal

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

    Industrial Technologies Industrial Technologies Find More Like This Return to Search Analytical Spectroscopy Idaho National Laboratory Contact INL About This Technology Technology Marketing Summary The use of lasers has become increasingly widespread, especially for manufacturing products and material analysis. Recently, laser desorption (LD) techniques for mass spectrometry have attracted attention because it produces intact molecular ions, avoids surface charging issues, and allows tuning of

  16. Atomic Structure Calculations from the Los Alamos Atomic Physics Codes

    DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

    Cowan, R. D.

    The well known Hartree-Fock method of R.D. Cowan, developed at Los Alamos National Laboratory, is used for the atomic structure calculations. Electron impact excitation cross sections are calculated using either the distorted wave approximation (DWA) or the first order many body theory (FOMBT). Electron impact ionization cross sections can be calculated using the scaled hydrogenic method developed by Sampson and co-workers, the binary encounter method or the distorted wave method. Photoionization cross sections and, where appropriate, autoionizations are also calculated. Original manuals for the atomic structure code, the collisional excitation code, and the ionization code, are available from this website. Using the specialized interface, you will be able to define the ionization stage of an element and pick the initial and final configurations. You will be led through a series of web pages ending with a display of results in the form of cross sections, collision strengths or rates coefficients. Results are available in tabular and graphic form.

  17. Low-loss electron energy loss spectroscopy: An atomic-resolution...

    Office of Scientific and Technical Information (OSTI)

    The theoretical component of the method combines density functional theory-based ... The theoretical analysis identifies the spatial and orbital origins of excitations, ...

  18. Higher-order spin-noise spectroscopy of atomic spins in fluctuating...

    Office of Scientific and Technical Information (OSTI)

    This content will become publicly available on March 9, 2017 Title: Higher-order ... Free Publicly Accessible Full Text This content will become publicly available on March 9, ...

  19. Search for: All records | SciTech Connect

    Office of Scientific and Technical Information (OSTI)

    Corporation (BNC) (United States) Bettis Atomic Power Laboratory (BAPL), West Mifflin, PA ... verified by X-ray diffraction (XRD), Mssbauer and X-ray absorption spectroscopy (XAS). ...

  20. Search for: All records | SciTech Connect

    Office of Scientific and Technical Information (OSTI)

    Corporation (BNC) (United States) Bettis Atomic Power Laboratory (BAPL), West Mifflin, PA ... goethite minerals (Fe1-xMnxOOH) was studied using X-ray absorption spectroscopy. ...