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Note: This page contains sample records for the topic "x-ray absorption spectroscopy" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
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1

X-ray absorption spectroscopy  

E-Print Network (OSTI)

009-9473-8 REVIEW X-ray absorption spectroscopy Junko Yano Æand application of X-ray absorption spectroscopy, bothX-ray absorption near-edge structure (XANES) and extended X-

Yano, Junko; Yachandra, Vittal K.

2009-01-01T23:59:59.000Z

2

X-ray Absorption Spectroscopy  

E-Print Network (OSTI)

type: Review X-ray Absorption Spectroscopy Junko Yano andPhotosystem II; XAS, X-ray absorption spectroscopy; EXAFS,X-ray absorption fine structure; EPR, electron paramagnetic

Yano, Junko

2010-01-01T23:59:59.000Z

3

SMB, X-ray Absorption Spectroscopy  

NLE Websites -- All DOE Office Websites (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...

4

X-ray Absorption Spectroscopy  

SciTech Connect

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

Yano, Junko; Yachandra, Vittal K.

2009-07-09T23:59:59.000Z

5

X-Ray Absorption Spectroscopy of Metallobiomolecules  

E-Print Network (OSTI)

2/9/07 1 X-Ray Absorption Spectroscopy of Metallobiomolecules The Outskirts of Structural Biology 9, 07] This is a tutorial about the use of X-ray Absorption Spectroscopy (XAS) in biology, RG; Eisenberger, P; Kincaid, BM "X-ray Absorption Spectroscopy of Biological Molecules" Annu. Rev

Scott, Robert A.

6

X-Ray Absorption Spectroscopy of Metallobiomolecules  

E-Print Network (OSTI)

9/6/09 1 X-Ray Absorption Spectroscopy of Metallobiomolecules The Outskirts of Structural Biology 6, 09] This is a tutorial about the use of X-ray Absorption Spectroscopy (XAS) in biology, RG; Eisenberger, P; Kincaid, BM "X-ray Absorption Spectroscopy of Biological Molecules" Annu. Rev

Scott, Robert A.

7

X-ray Absorption Spectroscopy of Biologically Relevant Systems  

E-Print Network (OSTI)

308, Messer, B. M. X-ray Absorption Spectroscopy of AqueousSarcosine via X-ray Absorption Spectroscopy 5.1 Introductionwith Carboxylate by X-Ray Absorption Spectroscopy of Liquid

Uejio, Janel Sunayo

2010-01-01T23:59:59.000Z

8

Ultrafast X-ray Absorption Spectroscopy using Laser-Driven Electron X-ray Sources (LEXS)  

E-Print Network (OSTI)

: ultrafast x-rays, x-ray absorption spectroscopy, terawatt lasers, ultrafast reaction dynamics, atomic motion atomic motion by scrutinizing the changes in x- ray absorption spectra during reactions. FirstUltrafast X-ray Absorption Spectroscopy using Laser-Driven Electron X-ray Sources (LEXS) Guangjun

Guo, Ting

9

X-RAY ABSORPTION SPECTROSCOPY FOR THE CHEMICAL CHARACTERIZATION OF ATMOSPHERIC AEROSOLS  

E-Print Network (OSTI)

November 11-16 9 1979 X-RAY ABSORPTION SPECTROSCOPY FOR THEUniversity of California. ABSORPTION SPECTROSCOPY FOR THEand x-ray emission and absorption spectroscopy. The first

Jaklevic, J. M.

2011-01-01T23:59:59.000Z

10

X-ray Absorption Spectroscopy Study of Prototype Chemical Systems: Theory vs. Experiment  

E-Print Network (OSTI)

acids by Near Edge X-ray Absorption Fine Structure (NEXAFS)X-ray Absorption Spectroscopy Study of Prototype ChemicalGlaeser Spring 2010 X-ray Absorption Spectroscopy Study of

Schwartz, Craig Philip

2010-01-01T23:59:59.000Z

11

X-ray absorption spectroscopy at the Ni-K edge in Stackhousia tryonii Bailey hyperaccumulator  

E-Print Network (OSTI)

X-ray absorption spectroscopy at the Ni–K edge inin vivo by micro x-ray absorption spectroscopy (XAS) at theNi–K edge. Both x-ray absorption near edge structure and

Kachenko, A.

2009-01-01T23:59:59.000Z

12

AN X-RAY ABSORPTION SPECTROSCOPY STUDY OF MANGANESE CONTAINING COMPOUNDS AND PHOTOSYNTHETIC SPINACH CHLOROPLASTS  

E-Print Network (OSTI)

II. Extended X-ray Absorption Fine Structure (EXAFS) TheoryIII. X-ray Absorption Spectroscopy (XAS) ExperimentIII. EXTENDED X-RAY ABSORPTION FINE STRUCTURE (EXAFS) DATA

Kirby, Jon Allan

2012-01-01T23:59:59.000Z

13

Transient x-ray absorption spectroscopy of hydrated halogen atom  

E-Print Network (OSTI)

Time-resolved x-ray absorption spectroscopy has been used to observe the transient species generated by one-photon detachment of an electron from aqueous bromide. The K-edge spectrum of the short-lived Br(0) atom exhibits a resonant 1s-4p transition...

Elles, Christopher G.; Shkrob, Ilya A.; Crowell, Robert A.; Arms, Dohn A.; Landahl, Eric C.

2008-02-11T23:59:59.000Z

14

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

SciTech Connect

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 (?E/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.

Katayama, Tetsuo; Togashi, Tadashi; Tono, Kensuke; Kameshima, Takashi [Japan Synchrotron Radiation Research Institute, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5198 (Japan)] [Japan Synchrotron Radiation Research Institute, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5198 (Japan); Inubushi, Yuichi; Sato, Takahiro; Hatsui, Takaki; Yabashi, Makina [RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5148 (Japan)] [RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5148 (Japan); Obara, Yuki; Misawa, Kazuhiko [Department of Applied Physics, Tokyo University of Agriculture and Technology, 2-24-16 Naka-cho, Koganei, Tokyo 184-8588 (Japan)] [Department of Applied Physics, Tokyo University of Agriculture and Technology, 2-24-16 Naka-cho, Koganei, Tokyo 184-8588 (Japan); Bhattacharya, Atanu; Kurahashi, Naoya [Department of Chemistry, Graduate School of Science, Kyoto University, Kitashirakawa-Oiwakecho, Sakyo-ku, Kyoto 606-8502 (Japan)] [Department of Chemistry, Graduate School of Science, Kyoto University, Kitashirakawa-Oiwakecho, Sakyo-ku, Kyoto 606-8502 (Japan); Ogi, Yoshihiro [Molecular Reaction Dynamics Research Team, RIKEN Center for Advanced Photonics, 2-1 Hirosawa, Wako 351-0198 (Japan)] [Molecular Reaction Dynamics Research Team, RIKEN Center for Advanced Photonics, 2-1 Hirosawa, Wako 351-0198 (Japan); Suzuki, Toshinori [Department of Chemistry, Graduate School of Science, Kyoto University, Kitashirakawa-Oiwakecho, Sakyo-ku, Kyoto 606-8502 (Japan) [Department of Chemistry, Graduate School of Science, Kyoto University, Kitashirakawa-Oiwakecho, Sakyo-ku, Kyoto 606-8502 (Japan); Molecular Reaction Dynamics Research Team, RIKEN Center for Advanced Photonics, 2-1 Hirosawa, Wako 351-0198 (Japan)

2013-09-23T23:59:59.000Z

15

Iron Species in Argonne Premium Coal Samples:? An Investigation Using X-ray Absorption Spectroscopy  

Science Journals Connector (OSTI)

Iron Species in Argonne Premium Coal Samples:? An Investigation Using X-ray Absorption Spectroscopy ... Chemistry Division, Argonne National Laboratory, 9700 S. Cass Ave., Argonne, Illinois 60439 ... Iron K-edge X-ray absorption spectroscopy (XAS) has been used to examine the iron species that are present within the Argonne Premium Coal Samples. ...

Stephen R. Wasserman; Randall E. Winans; Robert McBeth

1996-03-20T23:59:59.000Z

16

Structural analysis of sulfur in natural rubber using X-ray absorption near-edge spectroscopy  

Science Journals Connector (OSTI)

The opportunity to employ X-ray absorption near-edge spectroscopy techniques to investigate the alteration of the structural properties of sulfur in various vulcanized rubber sheets is presented.

Pattanasiriwisawa, W.

2008-07-11T23:59:59.000Z

17

X-ray Absorption and Emission Spectroscopy Study of the Effect of Doping on the Low Energy Electronic Structure of PrFeAsO1-[delta  

E-Print Network (OSTI)

X-ray Absorption and Emission Spectroscopy Study of theusing soft X-ray absorption and emission spectroscopy. The2. (a) Oxygen 1s x-ray absorption spectra of PrFeAsO 1-? (?

Freelon, Byron

2010-01-01T23:59:59.000Z

18

A Laboratory-based Hard X-ray Monochromator for High-Resolution X-ray Emission Spectroscopy and X-ray Absorption Near Edge Structure Measurements  

E-Print Network (OSTI)

We report the development of a laboratory-based Rowland-circle monochromator that incorporates a low poer x-ray (bremsstrahlung) tube source, a spherically-bent crystal analyzer (SBCA), 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 dmeonstrating 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 (XES) comparable to those achived at monochromatized spectroscopy beamlines at synchrotron light sources. For x-ray absorption near edge structure (XANES), 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-powered line-foc...

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

2014-01-01T23:59:59.000Z

19

X-ray absorption spectroscopy on solid krypton up to 20 GPa  

Science Journals Connector (OSTI)

High-pressure properties of krypton were investigated by energy-dispersive extended x-ray absorption fine-structure spectroscopy in a diamond anvil cell at room temperature. The equation of state agrees very well with x-ray diffraction data. The pressure dependence of the Debye-Waller factor was determined and compared with calculations using pair potentials. The analysis of the x-ray absorption near-edge structure part of the spectrum shows the possibility of measuring the pressure in bubbles of krypton implanted in metallic matrices.

A. Polian; J. P. Itie; E. Dartyge; A. Fontaine; G. Tourillon

1989-02-15T23:59:59.000Z

20

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

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

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

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


21

X-ray Absorption Spectroscopy of Transition Metal-Magnesium Hydride Thin Films  

E-Print Network (OSTI)

X-ray Absorption Spectroscopy of Transition Metal-Magnesium Hydride Thin Films T. J. Richardsona@lbl.gov Abstract Mixed metal thin films containing magnesium and a first-row transition element exhibit very large and coordination of the magnesium and transition metal atoms during hydrogen absorption were studied using dynamic

22

Double-resonant x-ray and microwave absorption: Atomic spectroscopy of precessional orbital and spin dynamics  

E-Print Network (OSTI)

Double-resonant x-ray and microwave absorption: Atomic spectroscopy of precessional orbital of atomic species driven to ferromagnetic resonance. X-ray absorption measurements performed as a function of paramagnetic atoms can be determined by de- tecting the absorption or emission of light modulated by a MW field

Brune, Harald

23

X-ray absorption spectroscopy of the cubic and hexagonal polytypes of zinc sulfide B. Gilbert,1,  

E-Print Network (OSTI)

X-ray absorption spectroscopy of the cubic and hexagonal polytypes of zinc sulfide B. Gilbert,1 Received 18 June 2002; published 26 December 2002 We investigate the sensitivity of x-ray absorption. Experimental spectra and multiple-scattering calculations are reported at the major absorption edges

Haskel, Daniel

24

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

SciTech Connect

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.

Paesler, M.; Sayers, D.

1988-12-01T23:59:59.000Z

25

Precision recording of near-edge profiles of x-ray absorption edges: an improved x-ray spectroscopy  

SciTech Connect

The intense, highly monochromatized X-ray beams available at the Cornell High Energy Synchroton Source facility permit one to plot the fine structure at absorption edges of elements with atomic number Z > 18. With the simple device described in this report, the authors have recorded distinctive features in absorption profiles, with a reproducibility better than +/- 50 meV for the major jumps, when measured with reference to a selected material, generally the metal. These spectra, which reflect locations of the upper states into which the photoelectrons are propelled, can be obtained without pretreatment of the sample (other than grinding to a fine powder) under ambient atmospheric conditions. Of course, spectra at low or high temperatures, under controlled atmospheres, can also be recorded with a more elaborative device. This technique complements information derived from electron energy loss spectroscopy and provides a fingerprint of modifications in the electronic structure of the element induced by the coordinating shell of surrounding atoms. It is a discriminating analytical probe for characterizing compositional changes in the first coordination shell around the selected atomic centers, due to processing of amorphous (or very finely divided) materials.

Chiu, N.S.; Bauer, S.H.

1988-08-01T23:59:59.000Z

26

Note: Application of a pixel-array area detector to simultaneous single crystal x-ray diffraction and x-ray absorption spectroscopy measurements  

SciTech Connect

X-ray diffraction (XRD) and X-ray absorption spectroscopy (XAS) are two main x-ray techniques in synchrotron radiation facilities. In this Note, we present an experimental setup capable of performing simultaneous XRD and XAS measurements by the application of a pixel-array area detector. For XRD, the momentum transfer in specular diffraction was measured by scanning the X-ray energy with fixed incoming and outgoing x-ray angles. By selecting a small fixed region of the detector to collect the XRD signal, the rest of the area was available for collecting the x-ray fluorescence for XAS measurements. The simultaneous measurement of XRD and X-ray absorption near edge structure for Pr{sub 0.67}Sr{sub 0.33}MnO{sub 3} film was demonstrated as a proof of principle for future time-resolved pump-probe measurements. A static sample makes it easy to maintain an accurate overlap of the X-ray spot and laser pump beam.

Sun, Cheng-Jun, E-mail: cjsun@aps.anl.gov; Brewe, Dale L.; Heald, Steve M. [Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439 (United States)] [Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Zhang, Bangmin [Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439 (United States) [Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Department of Materials Science and Engineering, National University of Singapore, 117575 Singapore (Singapore); NUSNNI-Nanocore, National University of Singapore, 117411 Singapore (Singapore); Chen, Jing-Sheng; Chow, G. M. [Department of Materials Science and Engineering, National University of Singapore, 117575 Singapore (Singapore)] [Department of Materials Science and Engineering, National University of Singapore, 117575 Singapore (Singapore); Venkatesan, T. [NUSNNI-Nanocore, National University of Singapore, 117411 Singapore (Singapore) [NUSNNI-Nanocore, National University of Singapore, 117411 Singapore (Singapore); Department of Physics, National University of Singapore, 117542 Singapore (Singapore); Department of Electrical and Computer Engineering, National University of Singapore, 117575 Singapore (Singapore)

2014-04-15T23:59:59.000Z

27

Image stack alignment in full-field X-ray absorption spectroscopy using SIFT_PyOCL  

Science Journals Connector (OSTI)

An application of the Scale-Invariant Feature Transform (SIFT) algorithm for image stack alignment in full-field X-ray absorption spectroscopy is described and a Python-OpenCL implementation of this algorithm is presented.

Paleo, P.

2014-02-04T23:59:59.000Z

28

Instrument for x-ray absorption spectroscopy with in situ electrical control characterizations  

SciTech Connect

We report a synchrotron-based setup capable of performing x-ray absorption spectroscopy and x-ray magnetic circular dichroism with simultaneous electrical control characterizations. The setup can enable research concerning electrical transport, element- and orbital-selective magnetization with an in situ fashion. It is a unique approach to the real-time change of spin-polarized electronic state of a material/device exhibiting magneto-electric responses. The performance of the setup was tested by probing the spin-polarized states of cobalt and oxygen of Zn{sub 1-x}Co{sub x}O dilute magnetic semiconductor under applied voltages, both at low (?20 K) and room temperatures, and signal variations upon the change of applied voltage were clearly detected.

Huang, Chun-Chao; Chang, Shu-Jui; Yang, Chao-Yao; Tseng, Yuan-Chieh [Department of Materials Science and Engineering, National Chiao Tung University, Hsinchu, Taiwan (China)] [Department of Materials Science and Engineering, National Chiao Tung University, Hsinchu, Taiwan (China); Chou, Hsiung [Department of Physics, National Sun Yat-sen University, Kaohsiung, Taiwan (China)] [Department of Physics, National Sun Yat-sen University, Kaohsiung, Taiwan (China)

2013-12-15T23:59:59.000Z

29

Diamond sensors and polycapillary lenses for X-ray absorption spectroscopy  

SciTech Connect

Diamond sensors are evaluated as incident beam monitors for X-ray absorption spectroscopy experiments. These single crystal devices pose a challenge for an energy-scanning experiment using hard X-rays due to the effect of diffraction from the crystalline sensor at energies which meet the Bragg condition. This problem is eliminated by combination with polycapillary lenses. The convergence angle of the beam exiting the lens is large compared to rocking curve widths of the diamond. A ray exiting one capillary from the lens meets the Bragg condition for any reflection at a different energy from the rays exiting adjacent capillaries. This serves to broaden each diffraction peak over a wide energy range, allowing linear measurement of incident intensity over the range of the energy scan. Extended X-ray absorption fine structure data are measured with a combination of a polycapillary lens and a diamond incident beam monitor. These data are of comparable quality to data measured without a lens and with an ionization chamber monitoring the incident beam intensity.

Ravel, B. [National Institute of Standards and Technology, Gaithersburg, Maryland 20899 (United States)] [National Institute of Standards and Technology, Gaithersburg, Maryland 20899 (United States); Attenkofer, K. [Photon Sciences Division, Brookhaven National Laboratory, Upton, New York 11973-5000 (United States)] [Photon Sciences Division, Brookhaven National Laboratory, Upton, New York 11973-5000 (United States); Bohon, J. [Center for Synchrotron Biosciences, Case Western Reserve University, Cleveland, Ohio 44106 (United States)] [Center for Synchrotron Biosciences, Case Western Reserve University, Cleveland, Ohio 44106 (United States); Muller, E. [Department of Physics and Astronomy, Stony Brook University, Stony Brook, New York 11974-3800 (United States)] [Department of Physics and Astronomy, Stony Brook University, Stony Brook, New York 11974-3800 (United States); Smedley, J. [Instrumentation Division, Brookhaven National Laboratory, Upton, New York 11973-5000 (United States)] [Instrumentation Division, Brookhaven National Laboratory, Upton, New York 11973-5000 (United States)

2013-10-15T23:59:59.000Z

30

Automated system for x-ray absorption spectroscopy of nanoparticle nucleation and growth  

SciTech Connect

X-ray absorption spectroscopy (XAS) is a useful tool for studying nanoparticle synthesis and growth. Described here is a system for automating synthesis and data collection, allowing time-resolved XAS measurements at a synchrotron to be accurately combined with measurements made under identical conditions elsewhere, and promising the ability to use XAS with experiments in combinatorial chemistry. The primary components of this system are a commercial parallel processor and a custom flow cell. The system has been used to collect data on the synthesis of iron oxides from iron(II) acetylacetonate.

Calvin, S.; Carpenter, E.E.; Cestone, V.; Kurihara, L.K.; Harris, V.G.; Brown, E.C. [Naval Research Lab, Code 6360, Washington, DC 20375 (United States); Sarah Lawrence College, 1 Mead Way, Bronxville, New York 10708 (United States)

2005-01-01T23:59:59.000Z

31

X-RAY ABSORPTION SPECTROSCOPY OF TRANSITION METAL-MAGNESIUM HYDRIDE FILMS  

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

Spectroscopy of Transition Metal-Magnesium Spectroscopy of Transition Metal-Magnesium Hydride Thin Films T. J. Richardson a, *, B. Farangis a , J. L. Slack a , P. Nachimuthu b , R. Pereira b , N. Tamura b , and M. Rubin a a Environmental Energy Technologies Division, b Advanced Light Source, Ernest Orlando Lawrence Berkeley National Laboratory Berkeley, California 94720, USA *Corresponding author, E-mail address: tjrichardson@lbl.gov Abstract Mixed metal thin films containing magnesium and a first-row transition element exhibit very large changes in both reflectance and transmittance on exposure to hydrogen gas. Changes in electronic structure and coordination of the magnesium and transition metal atoms during hydrogen absorption were studied using dynamic in situ transmission mode X-ray absorption

32

A Fern Fatale - X-ray Absorption Spectroscopy Imaging an Arsenic-Loving  

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

Fern Fatale - X-ray Absorption Spectroscopy Imaging of an Arsenic-Loving Fern Fatale - X-ray Absorption Spectroscopy Imaging of an Arsenic-Loving Fern For many people, arsenic is synonymous with poison, so it is perhaps a surprise that some plants, such as the fern Pteris vittata (Figure 1) seem to quite deliberately 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 evidence that arsenic is required for health [1], this is debatable. On the other hand, the poisonous nature of arsenic compounds was understood by the ancient Greeks and Romans, and it has been used throughout history as a homicidal and suicidal agent. It is found in two environmentally common oxy acids; arsenous acid (H3AsO3), and arsenic acid (H3AsO4), whose salts are known as arsenites and arsenates, respectively. Of these, the trivalent arsenic species are the most toxic. The infamous agent of murder is arsenic trioxide (white arsenic or As2O3), which is simply the (reputedly tasteless) anhydride of arsenous acid.

33

Correlated single-crystal electronic absorption spectroscopy and X-ray crystallography at NSLS beamline X26-C  

SciTech Connect

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.

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

2011-05-01T23:59:59.000Z

34

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

SciTech Connect

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.

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

2011-12-31T23:59:59.000Z

35

Ge doped HfO{sub 2} thin films investigated by x-ray absorption spectroscopy  

SciTech Connect

The stability of the tetragonal phase of Ge doped HfO{sub 2} thin films on Si(100) was investigated. Hf(Ge)O{sub 2} films with Ge atomic concentrations varying from 0% to 15% were deposited by remote plasma chemical vapor deposition. The atomic structure on the oxide after rapid thermal annealing was investigated by x-ray absorption spectroscopy of the O and Ge K edges and by Rutherford backscattering spectrometry. The authors found that Ge concentrations as low as 5 at. % effectively stabilize the tetragonal phase of 5 nm thick Hf(Ge)O{sub 2} on Si and that higher concentrations are not stable to rapid thermal annealing at temperatures above 750 deg. C.

Miotti, Leonardo; Bastos, Karen P.; Lucovsky, Gerald; Radtke, Claudio; Nordlund, Dennis [Department of Physics, North Carolina State University, Box 8202, Raleigh, North Carolina 27695-8202 (United States); Instituto de Quimica, Universidade Federal do Rio Grande do Sul, 91509-900 Porto Alegre (Brazil); Stanford Synchrotron Radiation Lightsource, Menlo Park, California 94025 (United States)

2010-07-15T23:59:59.000Z

36

The Chemistry os Spent Nuclear Fuel From X-Ray Absorption Spectroscopy  

SciTech Connect

Present and future nuclear fuel cycles will require an understanding of the complex chemistry of trace fission products and transuranium actinides in spent nuclear fuel (SNF). Because of the unique analytical challenges presented by SNF to the materials scientist, many of its fundamental physical and chemical properties remain poorly understood, especially on the microscopic scale. Such an understanding of the chemical states of radionuclides in SNF would benefit development of technologies for fuel monitoring, fuel performance improvement and modeling, fuel reprocessing, and spent fuel storage and disposal. We have recently demonstrated the use of synchrotron x-ray absorption spectroscopy (XAS) to examine crystal chemical properties of actinides and fission products in extracted specimens of SNF. Information obtained includes oxidation state, chemical bond coordination, and quantitative elemental concentration and distribution. We have also used XAS in a scanning mode to obtain x-ray spectral micrographs with resolution approaching 1 micron. A brief overview of the technique will be presented, along with findings on uranium, plutonium, neptunium, technetium, and molybdenum in commercial PWR SNF specimens.

F.A. Fortner; A.J. Kropf; J.C. Cunnane

2006-09-21T23:59:59.000Z

37

Low-Dimensional Water on Ru(0001)Model System for X-ray Absorption Spectroscopy Studies of Liquid Water  

SciTech Connect

We present an x-ray absorption spectroscopy results for fully broken to a complete H-bond network of water molecules on Ru(0001) by varying the morphology from isolated water molecules via two-dimensional clusters to a fully covered monolayer as probed by scanning tunneling microscopy. The sensitivity of x-ray absorption to the symmetry of H-bonding is further elucidated for the amino (-NH{sub 2}) group in glycine adsorbed on Cu(110) where the E-vector is parallel either to the NH donating an H-bond or to the non-H-bonded NH. The results give further evidence for the interpretation of the various spectral features of liquid water and for the general applicability of x-ray absorption spectroscopy to analyze H-bonded systems.

Nordlund, D

2012-02-14T23:59:59.000Z

38

Low-Dimensional Water on Ru(0001); Model System for X-ray Absorption Spectroscopy Studies of Liquid Water  

SciTech Connect

We present an x-ray absorption spectroscopy results for fully broken to a complete H-bond network of water molecules on Ru(0001) by varying the morphology from isolated water molecules via two-dimensional clusters to a fully covered monolayer as probed by scanning tunneling microscopy. The sensitivity of x-ray absorption to the symmetry of H-bonding is further elucidated for the amino (-NH{sub 2}) group in glycine adsorbed on Cu(110) where the E-vector is parallel either to the NH donating an H-bond or to the non-H-bonded NH. The results give further evidence for the interpretation of the various spectral features of liquid water and for the general applicability of x-ray absorption spectroscopy to analyze H-bonded systems.

Nordlund, D.; Ogasawara, H.; Andersson, K.J.; Tatarkhanov, M.; Salmeron, M.; Pettersson, L. G. M.; Nilsson, A.

2009-05-11T23:59:59.000Z

39

Chapter 1 - The Impacts of X-Ray Absorption Spectroscopy on Understanding Soil Processes and Reaction Mechanisms  

SciTech Connect

During the last two decades, X-ray absorption spectroscopy (XAS) has developed into a mature technique for obtaining the speciation (e.g., oxidation state) and short-range structure of elements present in soils and sediments. XAS encompasses both X-ray absorption near-edge structure (XANES) spectroscopy and extended X-ray absorption fine structure (EXAFS) spectroscopy. XAS has a number of advantageous qualities for studying soils and sediments, which include elemental specificity, sensitivity to the local chemical and structural state of an element, and the ability to analyze materials in situ. This information allows accurate determination of oxidation state, type of nearest neighbors, coordination number, bond distance, and orbital symmetries of the X-ray absorbing element. In this review, we examine the application of a wide variety of synchrotron X-ray techniques to fundamental issues in environmental soil chemistry. Additionally, we examine the application of microfocused and time-resolved XAS to determine speciation (e.g., oxidation state and/or local coordination environment) and transformation kinetics of contaminants in heterogeneous environmental systems. During the last three decades, XAS has a played a critical role in furthering our understanding of a myriad of environmental systems and will continue to do so into the foreseeable future.

Ginder-Vogel, Matthew; Sparks, Donald L. (Delaware)

2011-11-17T23:59:59.000Z

40

State of Ni in catalysts for glycerol hydrogenation and methane steam reforming as studied by X-ray absorption spectroscopy  

Science Journals Connector (OSTI)

X-ray absorption spectroscopy is used to study 1% Ni/Al2O3, 5% Ni/Al2O3, and 5% Ni/TiO2 catalysts for glycerol and methane conversion. The effect of treatment in H2 under microwave irradiation on the reduction of...

O. P. Tkachenko; L. M. Kustov

2013-06-01T23:59:59.000Z

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


41

Communications: Near edge x-ray absorption fine structure spectroscopy of aqueous adenosine triphosphate at the carbon and nitrogen  

E-Print Network (OSTI)

triphosphate at the carbon and nitrogen K-edges Daniel N. Kelly,1 Craig P. Schwartz,1,2 Janel S. Uejio,1 online xx xx xxxx Near edge x-ray absorption fine structure NEXAFS spectroscopy at the nitrogen-sphere association of Cu2+ did create observable broadening of the nitrogen spectrum, whereas outer

Cohen, Ronald C.

42

Study of hard disk and slider surfaces using X-ray photoemission electron microscopy and near-edge X-ray absorption fine structure spectroscopy  

SciTech Connect

X-ray Photo Emission Electron Microscopy (X-PEEM) and Near Edge X-ray Absorption Fine Structure (NEXAFS) spectroscopy were applied to study the properties of amorphous hard carbon overcoats on disks and sliders, and the properties of the lubricant. The modification of lubricants after performing thermal desorption studies was measured by NEXAFS, and the results are compared to the thermal desorption data. The study of lubricant degradation in wear tracks is described. Sliders were investigated before and after wear test, and the modification of the slider coating as well as the transfer of lubricant to the slider was studied. The studies show that the lubricant is altered chemically during the wear. Fluorine is removed and carboxyl groups are formed.

Anders, S.; Stammler, T. [Lawrence Berkeley National lab., CA (United States). Advanced Light Source Div.; Bhatia, C.S. [SSD/IBM, San Jose, CA (United States); Stoehr, J. [IBM Research Div., San Jose, CA (United States). Almaden Research Center; Fong, W.; Chen, C.Y.; Bogy, D.B. [Univ. of California, Berkeley, CA (United States)

1998-04-01T23:59:59.000Z

43

X-RAY ABSORPTION STUDIES OF GRAPHITE INTERCALATES AND METAL-AMMONIA SOLUTION  

E-Print Network (OSTI)

I. INTRODUCTION A. X-Ray Absorption Spectroscopy B. Graphiteacknowledged. The X-Ray absorption data could not have beenI INTRODUCTION X-ray absorption, spectroscopy (XAS) has been

Robertson, A.S.

2010-01-01T23:59:59.000Z

44

Polarized x-ray-absorption spectroscopy of the uranyl ion: Comparison of experiment and theory  

SciTech Connect

The x-ray linear dichroism of the uranyl ion (UO{sub 2}{sup 2+}) in uranium {ital L}{sub 3}-edge extended x-ray-absorption fine structure (EXAFS), and {ital L}{sub 1}- and {ital L}{sub 3}-edge x-ray-absorption near-edge structure (XANES), has been investigated both by experiment and theory. A striking polarization dependence is observed in the experimental XANES and EXAFS for an oriented single crystal of uranyl acetate dihydrate [UO{sub 2}(CH{sub 3}CO{sub 2}){sub 2}{center_dot}2H{sub 2}O], with the x-ray polarization vector aligned either parallel or perpendicular to the bond axis of the linear uranyl cation (O-U-O). Single-crystal results are compared to experimental spectra for a polycrystalline uranyl acetate sample and to calculations using the {ital ab} {ital initio} multiple-scattering (MS) code FEFF 6. Theoretical XANES spectra for uranyl fluoride (UO{sub 2}F{sub 2}) reproduce all the features of the measured uranyl acetate spectra. By identifying scattering paths which contribute to individual features in the calculated spectrum, a detailed understanding of the {ital L}{sub 1}-edge XANES is obtained. MS paths within the uranyl cation have a notable influence upon the XANES. The measured {ital L}{sub 3}-edge EXAFS is also influenced by MS, especially when the x-ray polarization is parallel to the uranyl species. These MS contributions are extracted from the total EXAFS and compared to calculations. The best agreement with the isolated MS signal is obtained by using nonoverlapped muffin-tin spheres in the FEFF 6 calculation. This contrasts the {ital L}{sub 1}-edge XANES calculations, in which overlapping was required for the best agreement with experiment. {copyright} {ital 1996 The American Physical Society.}

Hudson, E.A.; Allen, P.G.; Terminello, L.J. [Glenn T. Seaborg Institute for Transactinium Science, Lawrence Livermore National Laboratory, University of California, Livermore, California 94551 (United States)] [Glenn T. Seaborg Institute for Transactinium Science, Lawrence Livermore National Laboratory, University of California, Livermore, California 94551 (United States); Denecke, M.A.; Reich, T. [Institut fuer Radiochemie, Forschungszentrum Rossendorf, Postfach 510119, D-01314 Dresden (Germany)] [Institut fuer Radiochemie, Forschungszentrum Rossendorf, Postfach 510119, D-01314 Dresden (Germany)

1996-07-01T23:59:59.000Z

45

X-ray absorption spectroscopy from H-passivated porous Si and oxidized Si nanocrystals  

SciTech Connect

Quantum confinement in nanoscale Si structures is widely believed to be responsible for the visible luminescence observed from anodically etched porous silicon (por-Si), but little is known about the actual size or shape of these structures. Extended x-ray absorption fine structure data from a wide variety of por-Si samples show significantly reduced average Si coordination numbers due to the sizable contribution of surface-coordinated H. (The IUSI ratios, as large as 1.2, were independently confirmed by ir-absorption and {alpha}-recoil measurements.) The Si coordinations imply very large surface/volume ratios, enabling the average Si structures to be identified as crystalline particles (not wires) whose dimensions are typically <15 {Angstrom}. Comparison of the size-dependent peak luminescence energies with those of oxidized Si nanocrystals, whose shapes are known, shows remarkable agreement. Furthermore, near-edge x-ray absorption fine structure measurements of the nanocrystals shows the outer oxide and interfacial suboxide layers to be constant over a wide range of nanocrystal sizes. The combination of these results effectively rules out surface species as being responsible for the observed visible luminescence in por-Si, and strongly supports quantum confinement as the dominant mechanism occurring in Si particles which are substantially smaller than previously reported or proposed.

Schuppler, S.; Marcus, M.A. [AT and T Bell Labs., Murray Hill, NJ (United States); Friedman, S.L. [Stanford Univ., Palo Alto, CA (United States). Dept. of Applied Physics] [and others

1994-11-01T23:59:59.000Z

46

Design of a continuous-flow reactor for in situ x-ray absorption spectroscopy of solids in supercritical fluids  

SciTech Connect

This paper presents the design and performance of a novel high-temperature and high-pressure continuous-flow reactor, which allows for x-ray absorption spectroscopy or diffraction in supercritical water and other fluids under high pressure and temperature. The in situ cell consists of a tube of sintered, polycrystalline aluminum nitride, which is tolerant to corrosive chemical media, and was designed to be stable at temperatures up to 500 deg. C and pressures up to 30 MPa. The performance of the reactor is demonstrated by the measurement of extended x-ray absorption fine structure spectra of a carbon-supported ruthenium catalyst during the continuous hydrothermal gasification of ethanol in supercritical water at 400 deg. C and 24 MPa.

Dreher, M.; De Boni, E.; Nachtegaal, M.; Wambach, J.; Vogel, F. [Paul Scherrer Institut, 5232 Villigen PSI (Switzerland)

2012-05-15T23:59:59.000Z

47

Determination of the iron-sulfur distances in rubredoxin by x-ray absorption spectroscopy  

Science Journals Connector (OSTI)

...x-ray flux from the synchrotron radiation at the Stanford Synchroton Radiation Project has been used to study the extended x-ray...x-ray flux from the synchrotron radiation at the Stanford Synchroton Radiation Project has been used to study the extended x-ray...

R G Shulman; P Eisenberger; W E Blumberg; N A Stombaugh

1975-01-01T23:59:59.000Z

48

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

SciTech Connect

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.

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

2009-05-29T23:59:59.000Z

49

SMB, X-Ray Spectroscopy & Imaging  

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

Home X-Ray Spectroscopy & Imaging X-Ray Spectroscopy & Imaging SSRL has five hard X-ray Spectroscopy beamlines and three Microfocus Imaging beamlines dedicated to Biological and...

50

X-ray-absorption spectroscopy investigation of the martensitic structural transformation in the RCu (R=rare earth) series  

Science Journals Connector (OSTI)

We present an x-ray-absorption spectroscopy (XAS) investigation performed at the L1,3 edges of the rare earth Y K edge and K and L2,3 edges of copper in several R-Cu intermetallic compounds: RCu (R=Y,Gd,Tb), Y1-xTbxCu, and Y1-xTbxCuyAg1-y. XAS spectra at the different absorption edges evidence the apparition of a strong electronic perturbation in the systems after the martensitic transformation. The dynamics of the structural transformation is discussed in terms of the interplay between the modification of both d-band widening and s-d transfer pressure.

Jesús Chaboy and M. R. Ibarra

1995-08-01T23:59:59.000Z

51

X-ray Absorption Spectroscopy Identifies Calcium-Uranyl-Carbonate Complexes at Environmental Concentrations  

SciTech Connect

Current research on bioremediation of uranium-contaminated groundwater focuses on supplying indigenous metal-reducing bacteria with the appropriate metabolic requirements to induce microbiological reduction of soluble uranium(VI) to poorly soluble uranium(IV). Recent studies of uranium(VI) bioreduction in the presence of environmentally relevant levels of calcium revealed limited and slowed uranium(VI) reduction and the formation of a Ca-UO2-CO3 complex. However, the stoichiometry of the complex is poorly defined and may be complicated by the presence of a Na-UO2-CO3 complex. Such a complex might exist even at high calcium concentrations, as some UO2-CO3 complexes will still be present. The number of calcium and/or sodium atoms coordinated to a uranyl carbonate complex will determine the net charge of the complex. Such a change in aqueous speciation of uranium(VI) in calcareous groundwater may affect the fate and transport properties of uranium. In this paper, we present the results from X-ray absorption fine structure (XAFS) measurements of a series of solutions containing 50 lM uranium(VI) and 30 mM sodium bicarbonate, with various calcium concentrations of 0-5 mM. Use of the data series reduces the uncertainty in the number of calcium atoms bound to the UO2-CO3 complex to approximately 0.6 and enables spectroscopic identification of the Na-UO2-CO3 complex. At nearly neutral pH values, the numbers of sodium and calcium atoms bound to the uranyl triscarbonate species are found to depend on the calcium concentration, as predicted by speciation calculations.

Kelly, Shelly D [Argonne National Laboratory (ANL); Kemner, Kenneth M [Argonne National Laboratory (ANL); Brooks, Scott C [ORNL

2007-01-01T23:59:59.000Z

52

Advances in X-Ray Chemical Analysis, Japan, 45 (2014) ISSN 0911-7806 Role of Infrared Absorption Spectroscopy in the Forensic Analysis of  

E-Print Network (OSTI)

Spectroscopy in the Forensic Analysis of Wakayama Curry Arsenic Poisoning Case Anthony T. TU and Jun KAWAI #12 80523, U. S. A. 606-8501 Role of Infrared Absorption Spectroscopy in the Forensic Analysis of Wakayama-8 X-ray fluorescence analysis was the key scientific evidence for the forensic analysis

Jun, Kawai

53

The BioCAT undulator beamline 18ID: A facility for biological non-crystalline diffraction and x-ray absorption spectroscopy at the APS  

SciTech Connect

The 18ID undulator beamline of the Biophysics Collaborative Access Team at the Advanced Photon Source, Argonne, IL, USA, is a high-performance instrument designed for, and dedicated to, the study of partially ordered and disordered biological materials using the techniques of small-angle X-ray scattering, fiber diffraction, and X-ray absorption spectroscopy. The beamline and associated instrumentation are described in detail and examples of the representative experimental results are presented.

Fischetti, R.; Stepanov, S.; Rosenbaum, G.; Barrea, R.; Black, E.; Gore, D.; Heurich, R.; Kondrashkina, E.; Kropf, A.J.; Wang, S.; Zhang, K.; Irving, T.C.; Bunker, G.B. (IIT); (Georgia)

2008-07-02T23:59:59.000Z

54

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

SciTech Connect

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.

Llorens, Isabelle [CEA/DSM/INAC/SP2M/NRS, F-38054 Grenoble cedex 9 (France); Synchrotron SOLEIL - MARS beamline, L'Orme des Merisiers, F-91192 Gif sur Yvette (France); Lahera, Eric; Delnet, William; Proux, Olivier [Observatoire des Sciences de l'Univers de Grenoble, UMS 832 CNRS Universite Joseph Fourier, F-38041 Grenoble cedex 9 (France); BM30B/FAME beamline, ESRF, F-38043 Grenoble cedex 9 (France); Braillard, Aurelien; Hazemann, Jean-Louis; Prat, Alain; Testemale, Denis [BM30B/FAME beamline, ESRF, F-38043 Grenoble cedex 9 (France); Institut Neel, UPR 2940 CNRS, F-38042 Grenoble cedex 9 (France); Dermigny, Quentin; Gelebart, Frederic; Morand, Marc; Shukla, Abhay [Institut de Mineralogie et de Physique des Milieux Condenses, UMR 7590, 4 place Jussieu, F-75005 Paris (France); Bardou, Nathalie [Laboratoire de Photonique et de Nanostructures, UPR 20 CNRS, Route de Nozay, F-91460 Marcoussis (France); Ulrich, Olivier [CEA/DSM/INAC/SP2M/NRS, F-38054 Grenoble cedex 9 (France); BM32/IF beamline, ESRF, F-38043 Grenoble cedex 9 (France); Arnaud, Stephan; Berar, Jean-Francois; Boudet, Nathalie; Caillot, Bernard [Institut Neel, UPR 2940 CNRS, F-38042 Grenoble cedex 9 (France); BM02/D2AM beamline, ESRF, F-38043 Grenoble cedex 9 (France); Chaurand, Perrine; Rose, Jerome [Centre Europeen de Recherche et d'Enseignement des Geosciences de l'Environnement, UMR 7730, F-13545 Aix en Provence (France); and others

2012-06-15T23:59:59.000Z

55

TENDER ENERGY X-RAY ABSORPTION  

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

TENDER ENERGY X-RAY ABSORPTION TENDER ENERGY X-RAY ABSORPTION SPECTROSCOPY (TES) Project Team: S. Bare 1,2 , J. Brandes 3 , T. Buonassisi 4 , J. Chen 5,2 , M. Croft 6 , E. DiMasi 7 , A. Frenkel 8,2 , D. Hesterberg 9 , S. Hulbert 7,2 , S. Khalid 7 , S. Myneni 10 , P. Northrup 7,11 , E.T. Rasbury 11 , B. Ravel 12 , R. Reeder 11 , J. Rodriguez 7,2 , D. Sparks 5,13 , V. Stojanoff 7 , G. Waychunas 14 1 UOP LLC, 2 Synchrotron Catalysis Consortium, 3 Skidaway Inst. of Oceanography, 4 MIT Laboratory for Photovoltaics Research, 5 Univ. of Delaware, 6 Rutgers Univ., 7 Brookhaven National Lab, 8 Yeshiva Univ., 9 North Carolina State Univ., 10 Princeton Univ., 11 Stony Brook Univ., 12 NIST, 13 Delaware Environmental Inst., 14 Lawrence Berkeley National Lab TECHNIQUES: High performance and in-situ X-ray absorption spectroscopy and spatially-resolved XAS of

56

X-ray absorption study of the electronic structure of Mn-doped amorphous Si  

E-Print Network (OSTI)

X-ray absorption study of the electronic structure of Mn-?x ) is studied by X-ray absorption spectroscopy at the Mn Land featureless L 3,2 absorption peaks, corresponding to an

Zeng, Li

2008-01-01T23:59:59.000Z

57

Direct Determination of Pyrite Content in Argonne Premium Coals by the Use of Sulfur X-ray Near Edge Absorption Spectroscopy (S-XANES)  

Science Journals Connector (OSTI)

Direct Determination of Pyrite Content in Argonne Premium Coals by the Use of Sulfur X-ray Near Edge Absorption Spectroscopy (S-XANES) ... Argonne National Laboratory, Argonne, Illinois 60439 ... Argonne premium coal samples are used by researchers worldwide as standards in coal research. ...

Trudy B. Bolin

2010-10-01T23:59:59.000Z

58

Nitrogen Doping and Thermal Stability in HfSiOxNy Studied by Photoemission and X-ray Absorption Spectroscopy  

SciTech Connect

We have investigated nitrogen-doping effects into HfSiO{sub x} films on Si and their thermal stability using synchrotron-radiation photoemission and x-ray absorption spectroscopy. N 1s core-level photoemission and N K-edge absorption spectra have revealed that chemical-bonding states of N-Si{sub 3-x}O{sub x} and interstitial N{sub 2}-gas-like features are clearly observed in as-grown HfSiO{sub x}N{sub y} film and they decrease upon ultrahigh vacuum (UHV) annealing due to a thermal instability, which can be related to the device performance. Annealing-temperature dependence in Hf 4f and Si 2p photoemission spectra suggests that the Hf-silicidation temperature is effectively increased by nitrogen doping into the HfSiO{sub x} although the interfacial SiO{sub 2} layer is selectively reduced. No change in valence-band spectra upon UHV annealing suggests that crystallization of the HfSiO{sub x}N{sub y} films is also hindered by nitrogen doping into the HfSiO{sub x}.

Toyoda, Satoshi; Okabayashi, Jun; Takahashi, Haruhiko; Oshima, Masaharu; /Tokyo U.; Lee, Dong-Ick; Sun, Shiyu; sun, Steven; Pianetta, Piero A.; /SLAC, SSRL; Ando, Takashi; Fukuda, Seiichi; /SONY, Atsugi

2005-12-14T23:59:59.000Z

59

Soft X-Ray and Vacuum Ultraviolet Based Spectroscopy of the Actinides  

SciTech Connect

The subjects of discussion included: VUV photoelectron spectroscopy, X-ray photoelectron spectroscopy, Synchrotron-radiation-based photoelectron spectroscopy, Soft x-ray absorption spectroscopy, Soft x-ray emission spectroscopy, Inverse photoelectron spectroscopy, Bremstrahlung Isochromat Spectroscopy, Low energy IPES, Resonant inverse photoelectron spectroscopy.

Tobin, J G

2011-03-17T23:59:59.000Z

60

The electronic structure of poly(pyridine-2,5-diyl) investigated by soft x-ray absorption and emission spectroscopies  

E-Print Network (OSTI)

The electronic structure of the poly-pyridine conjugated polymer has been investigated by resonant and nonresonant inelastic X-ray scattering and X-ray absorption spectroscopies using synchrotron radiation. The measurements were made for both the carbon and nitrogen contents of the polymer. The analysis of the spectra has been carried out in comparison with molecular orbital calculations taking the repeat-unit cell as a model molecule of the polymer chain. The simulations indicate no significant differences in the absorption and in the non-resonant X-ray scattering spectra for the different isomeric geometries, while some isomeric dependence of the resonant spectra is predicted. The resonant emission spectra show depletion of the {\\pi} electron bands in line with symmetry selection and momentum conservation rules. The effect is most vizual for the carbon spectra; the nitrogen spectra are dominated by lone pair n orbital emission of {\\sigma} symmetry and are less frequency dependent.

Magnuson, M; Guo, J - H; Såthe, C; Agui, A; Nordgren, J; Luo, Y; Ågren, H; Johansson, N; Salaneck, W R; Horsburgh, L E; Monkman, A P; 10.1016/S0301-0104(98)00262-6

2012-01-01T23:59:59.000Z

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


61

Mechanism of Pb Adsorption to Fatty Acid Langmuir Monolayers Studied by X-ray Absorption Fine Structure Spectroscopy  

SciTech Connect

The local atomic environment of lead (Pb) adsorbed to a CH{sub 3}(CH{sub 2}){sub 19}COOH Langmuir monolayer was investigated in situ using grazing-incidence X-ray absorption fine structure (GI-XAFS) spectroscopy at the Pb L{sub III} edge. Measurements were performed at pH 6.5 of the 10{sup -5} M PbCl{sub 2} solution subphase, a condition under which grazing incidence diffraction (GID) revealed a large-area commensurate superstructure underneath the close-packed organic monolayer. The XAFS results indicate covalent binding of the Pb cations to the carboxyl headgroups, and the observed Pb-Pb coordination suggests that the metal is adsorbed as a hydrolysis polymer, rather than as individual Pb{sup 2+} ions. The data are consistent with a bidentate chelating mechanism and a one Pb atom to one carboxyl headgroup binding stoichiometry. We discuss how this adsorption model can explain the peculiarities observed with Pb in previous metal-Langmuir monolayer studies. A systematic study of lead perchlorate and lead acetate aqueous solutions is presented and used in the analysis. XAFS multiple scattering effects from alignment of the Pb-C-C atoms in the lead acetate solutions are reported.

Boyanov, M.I.; Kmetko, J.; Shibata, T.; Datta, A.; Dutta, P.; Bunker, B.A. (NWU); (Notre)

2010-09-30T23:59:59.000Z

62

X-ray Spectroscopy of Cool Stars  

E-Print Network (OSTI)

High-resolution X-ray spectroscopy has addressed not only various topics in coronal physics of stars, but has also uncovered important features relevant for our understanding of stellar evolution and the stellar environment. I summarize recent progress in coronal X-ray spectroscopy and in particular also discuss new results from studies of X-rays from pre-main sequence stars.

M. Guedel

2006-09-11T23:59:59.000Z

63

Electron Core-Hole Interaction in the X-Ray Absorption Spectroscopy of 3d Transition Metals  

Science Journals Connector (OSTI)

A fully relativistic scheme is presented that allows one to deal with the electronic band structure of a solid and the influence of the electron core-hole interaction on its x-ray absorption spectra on the same level. This is achieved in a parameter-free way by working throughout in the framework of the time-dependent density functional theory and linear response formalism. Application to the L2,3-absorption spectra of 3d transition metals demonstrates that the electron core-hole interaction intermixes the L2 and L3 partial spectra, strongly affecting the so-called branching ratio. The consequences of this for the magnetic circular x-ray dichroism sum rules are discussed.

J. Schwitalla and H. Ebert

1998-05-18T23:59:59.000Z

64

In Situ X-ray Absorption Near-Edge Structure Spectroscopy of ZnO Nanowire Growth During Chemical Bath Deposition  

SciTech Connect

Chemical bath deposition (CBD) offers a simple and inexpensive route to deposit semiconductor nanostructures, but lack of fundamental understanding and control of the underlying chemistry has limited its versatility. Here we report the first use of in situ X-ray absorption spectroscopy during CBD, enabling detailed investigation of both reaction mechanisms and kinetics of ZnO nanowire growth from zinc nitrate and hexamethylenetetramine (HMTA) precursors. Time-resolved X-ray absorption near-edge structure (XANES) spectra were used to quantify Zn(II) speciation in both solution and solid phases. ZnO crystallizes directly from [Zn(H{sub 2}O){sub 6}]{sup 2+} without long-lived intermediates. Using ZnO nanowire deposition as an example, this study establishes in situ XANES spectroscopy as an excellent quantitative tool to understand CBD of nanomaterials.

McPeak, Kevin M.; Becker, Matthew A.; Britton, Nathan G.; Majidi, Hasti; Bunker, Bruce A.; Baxter, Jason B. (Drexel); (Notre)

2010-12-03T23:59:59.000Z

65

SMB, X-ray Emission Spectroscopy  

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

Emission Spectroscopy Beam Line 6-2b X-ray Emission Spectroscopy Beam Line 6-2b is an advanced spectroscopy experimental station on the multidisciplinary general user wiggler Beam...

66

Hydrogen absorption in epitaxial W/Nb(001) and polycrystalline Fe/Nb(110) multilayers studied in-situ by X-ray/neutron scattering techniques and X-ray absorption spectroscopy  

SciTech Connect

Hydrogen can be absorbed in large quantities by 100 {angstrom} thin Nb layers embedded in epitaxial W/Nb and polycrystalline Fe/Nb multilayers. The solubility and the hydrogen-induced structural changes of the host lattice are explored in-situ by small-angle neutron/X-ray reflectometry and high-angle diffraction. These measurements reveal for both systems that the relative out-of-plane expansion of the Nb layers is considerably larger than the relative increase of the Nb interplanar spacing indicating two distinctly different mechanisms of hydrogen absorption. In Fe/Nb multilayers, hydrogen expands the Nb interplanar spacing in a continuous way as function of the external pressure. In contrast, the Nb lattice expansion is discontinuous in epitaxial W/Nb multilayers: A jump in the Nb(002) Bragg reflection position occurs at a critical hydrogen pressure of 1 mbar. In-situ EXAFS spectroscopy also exhibits an irreversible expansion of the Nb lattice in the film plane for p{sub H{sub 2}}> 1 mbar. This can be regarded as a structural phase transition from an exclusively out-of-plane to a three-dimensionally expanded state at low and high hydrogen pressures, respectively.

Klose, F.; Rehm, C.; Fieber-Erdmann, M.; Holub-Krappe, E.; Bleif, H. J.; Sowers, H.; Goyette, R.; Troger, L.; Maletta, H.

1999-11-02T23:59:59.000Z

67

Polarized X-Ray Absorption Spectroscopy of Single-Crystal Mn(V) Complexes Relevant to the Oxygen-Evolving Complex of Photosystem II  

SciTech Connect

High-valent Mn-oxo species have been suggested to have a catalytically important role in the water splitting reaction which occurs in the Photosystem II membrane protein. In this study, five- and six-coordinate mononuclear Mn(V) compounds were investigated by polarized X-ray absorption spectroscopy in order to understand the electronic structure and spectroscopic characteristics of high-valent Mn species. Single crystals of the Mn(V)-nitrido and Mn(V)-oxo compounds were aligned along selected molecular vectors with respect to the X-ray polarization vector using X-ray diffraction. The local electronic structure of the metal site was then studied by measuring the polarization dependence of X-ray absorption near-edge spectroscopy (XANES) pre-edge spectra (1s to 3d transition) and comparing with the results of density functional theory (DFT) calculations. The Mn(V)-nitrido compound, in which the manganese is coordinated in a tetragonally distorted octahedral environment, showed a single dominant pre-edge peak along the MnN axis that can be assigned to a strong 3dz2-4pz mixing mechanism. In the square pyramidal Mn(V)-oxo system, on the other hand, an additional peak was observed at 1 eV below the main pre-edge peak. This component was interpreted as a 1s to 3dxz,yz transition with 4px,y mixing, due to the displacement of the Mn atom out of the equatorial plane. The XANES results have been correlated to DFT calculations, and the spectra have been simulated using a TD (time-dependent)-DFT approach. The relevance of these results to understanding the mechanism of the photosynthetic water oxidation is discussed.

Yano, J.K.; Robblee, J.; Pushkar, Y.; Marcus, M.A.; Bendix, J.; Workman, J.M.; Collins, T.J.; Solomon, E.I.; George, S.D.; Yachandra, V.K.; /LBL, Berkeley /Copenhagen U. /Stanford U., Chem. Dept. /SLAC, SSRL

2007-10-16T23:59:59.000Z

68

Probing photochemical transformations at TiO{sub 2}/Pt and TiO{sub 2}/Ir interfaces using x-ray absorption spectroscopy  

SciTech Connect

Structural transformations at the TiO{sub 2}/Pt and TiO{sub 2}/Ir interfaces during UV-irradiation have been probed by X-ray absorption spectroscopy. Oxidation by the photogenerated holes results in the intercalation of Pt and Ir into the Titania matrix. The structural transformations observed with Pt and Ir nanoparticles anchored on TiO{sub 2} is different than the clustering of gold atoms observed in the TiO{sub 2}/Au system. Implications of such structural transformations on the photocatalytic activity of semiconductor photocatalyts are discussed.

Lahiri, Debdutta; Subramanian, V.; Bunker, Bruce A.; Kamat, Prashant V. [Synchrotron Radiation Section, Physics Group, Bhabha Atomic Research Centre, Mumbai 400085 (India); Department of Chemical Engineering, University of Illinois at Urbana-Champaign, Illinois 61801 (United States); Department of Physics, University of Notre Dame, Indiana 46556 (United States); Radiation Laboratory, University of Notre Dame, Indiana 46556 (United States)

2006-05-28T23:59:59.000Z

69

X-ray Spectroscopy of O Supergiant Winds: Shock Physics, Clumping, and Mass-Loss Rates  

E-Print Network (OSTI)

X-ray Spectroscopy of O Supergiant Winds: Shock Physics, Clumping, and Mass-Loss Rates David Cohen Li (Swarthmore '16), Kelley Langhans (Swarthmore '16) #12;Talk Outline Context of O star X-ray emission: wind shocks 1. X-ray constraints on the shocked wind plasma 2. X-ray absorption as a mass

Cohen, David

70

Sapphire analyzers for high-resolution x-ray spectroscopy.  

SciTech Connect

We present a sapphire (Al{sub 2}O{sub 3}) analyzer for high-resolution X-ray spectroscopy with 31-meV energy resolution. The analyzer is designed for resonant inelastic X-ray scattering (RIXS) measurements at the CuK{sub a} absorption edge near 8990 eV. The performance of the analyzer is demonstrated by measuring phonon excitations in beryllium because of its known dynamical structure and high counting rates.

Yavas, H.; Alp, E.; Sinn, H.; Alatas, A.; Said, A.; Shvydko, Y.; Toellner, T.; Khachatryan, R.; Billinge, S.; Hasan, Z.; Sturhahn, W.; Michigan State Univ.; Princeton Univ.; DESY

2007-11-11T23:59:59.000Z

71

X-ray Absorption Spectroscopic Analysis of Reductive [2Fe-2S] Cluster Degradation in Hyperthermophilic Archaeal Succinate:Caldariellaquinone  

E-Print Network (OSTI)

X-ray Absorption Spectroscopic Analysis of Reductive [2Fe-2S] Cluster Degradation, but moderately sensitive to reduction with excess dithionite. We used iron K-edge X-ray absorption spectroscopy

Scott, Robert A.

72

Femtosecond laser-induced modification of potassium-magnesium silicate glasses: An analysis of structural changes by near edge x-ray absorption spectroscopy  

SciTech Connect

The effects of femtosecond laser pulse irradiation on the glass structure of alkaline silicate glasses were investigated by x-ray absorption near edge structure spectroscopy using the beamline of the Physikalisch-Technische Bundesanstalt at the electron synchrotron BESSY II in Berlin (Germany) by analyzing the magnesium K-edge absorption peak for different laser fluences. The application of fluences above the material modification threshold (2.1 J/cm{sup 2}) leads to a characteristic shift of {approx}1.0 eV in the K-edge revealing a reduced ({approx}3%) mean magnesium bond length to the ligated oxygen ions (Mg-O) along with a reduced average coordination number of the Mg ions.

Seuthe, T.; Eberstein, M. [Fraunhofer-Institut fuer Keramische Technologien und Systeme (IKTS), Winterbergstrasse 28, 01277 Dresden (Germany); Hoefner, M.; Eichler, H. J.; Grehn, M. [Technische Universitaet Berlin, Institut fuer Optik und Atomare Physik, Strasse des 17. Juni 135, 10623 Berlin (Germany); Reinhardt, F. [Physikalisch-Technische Bundesanstalt (PTB), Abbestr. 2-12, 10587 Berlin (Germany); Tsai, W. J. [ITRI South, Industrial Technology Research Institute, 8 Gongyan Rd., Liu-jia District, Tainan City 73445, Taiwan (China); Bonse, J. [BAM Bundesanstalt fuer Materialforschung und - pruefung, Unter den Eichen 87, 12205 Berlin (Germany)

2012-05-28T23:59:59.000Z

73

Synchrotron x-ray absorption spectroscopy study of self-assembled nanoparticles synthesized from Fe(acac)3 and Pt(acac)2  

Science Journals Connector (OSTI)

The synchrotron X-ray absorption technique was used to complement electron microscopy in the investigation of nanoparticles synthesized from the coreduction of iron acetylacetonate, Fe(acac)3 and platinum acetylacetonate, Pt(acac)2. ...

K. Chokprasombat; C. Sirisathitkul; P. Harding; S. Chandarak; R. Yimnirun

2012-01-01T23:59:59.000Z

74

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

SciTech Connect

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.

Benkert, A., E-mail: andreas.benkert@kit.edu, E-mail: l.weinhardt@kit.edu [Institute for Photon Science and Synchrotron Radiation, Karlsruhe Institute of Technology (KIT), Hermann-v.-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany); Universität Würzburg, Experimentelle Physik VII, Am Hubland, 97074 Würzburg (Germany); Gemeinschaftslabor für Nanoanalytik, Karlsruhe Institute of Technology (KIT), 76021 Karlsruhe (Germany); Blum, M. [Department of Chemistry, University of Nevada, Las Vegas (UNLV), 4505 Maryland Parkway, Nevada 89154-4003 (United States) [Department of Chemistry, University of Nevada, Las Vegas (UNLV), 4505 Maryland Parkway, Nevada 89154-4003 (United States); Advanced Light Source, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720 (United States); Meyer, F. [Universität Würzburg, Experimentelle Physik VII, Am Hubland, 97074 Würzburg (Germany)] [Universität Würzburg, Experimentelle Physik VII, Am Hubland, 97074 Würzburg (Germany); Wilks, R. G. [Solar Energy Research, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Hahn-Meitner-Platz 1, 14109 Berlin (Germany)] [Solar Energy Research, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Hahn-Meitner-Platz 1, 14109 Berlin (Germany); Yang, W. [Advanced Light Source, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720 (United States)] [Advanced Light Source, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720 (United States); Bär, M. [Department of Chemistry, University of Nevada, Las Vegas (UNLV), 4505 Maryland Parkway, Nevada 89154-4003 (United States) [Department of Chemistry, University of Nevada, Las Vegas (UNLV), 4505 Maryland Parkway, Nevada 89154-4003 (United States); Solar Energy Research, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Hahn-Meitner-Platz 1, 14109 Berlin (Germany); Insitut für Physik und Chemie, Brandenburgische Technische Universität Cottbus-Senftenberg, Konrad-Wachsmann-Allee 1, 03046 Cottbus (Germany); and others

2014-01-15T23:59:59.000Z

75

X-ray spectroscopy of manganese clusters  

SciTech Connect

Much of this thesis represents the groundwork necessary in order to probe Mn clusters more productively than with conventional Mn K-edge XAS and is presented in Part 1. Part 2 contains the application of x-ray techniques to Mn metalloproteins and includes a prognosis at the end of each chapter. Individual Mn oxidation states are more readily distinguishable in Mn L-edge spectra. An empirical mixed valence simulation routine for determining the average Mn oxidation state has been developed. The first Mn L-edge spectra of a metalloprotein were measured and interpreted. The energy of Mn K{beta} emission is strongly correlated with average Mn oxidation state. K{beta} results support oxidation states of Mn(III){sub 2}(IV){sub 2} for the S{sub 1} state of Photosystem II chemical chemically reduced preparations contain predominantly Mn(II). A strength and limitation of XAS is that it probes all of the species of a particular element in a sample. It would often be advantageous to selectively probe different forms of the same element. The first demonstration that chemical shifts in x-ray fluorescence energies can be used to obtain oxidation state-selective x-ray absorption spectra is presented. Spin-dependent spectra can also be used to obtain a more simplified picture of local structure. The first spin-polarized extended x-ray absorption fine structure using Mn K{beta} fluorescence detection is shown.

Grush, M.M. [Univ. of California, Davis, CA (United States). Dept. of Applied Science; [Lawrence Berkeley National Lab., CA (United States). Energy and Environment Div.

1996-06-01T23:59:59.000Z

76

X-ray absorption fine structure and magnetization characterization...  

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

characterization of the metallic Co component in Co-doped ZnO thin films . X-ray absorption fine structure and magnetization characterization of the metallic Co...

77

Surface complexation and precipitate geometry for aqueous Zn(II) sorption on ferrihydrite I: X-ray absorption extended fine structure spectroscopy analysis  

Science Journals Connector (OSTI)

“Two-line” ferrihydrite samples precipitated and then exposed to a range of aqueous Zn solutions (10?5 to 10?3 M), and also coprecipitated in similar Zn solutions (pH 6.5), have been examined by Zn and Fe K-edge X-ray absorption spectroscopy. Typical Zn complexes on the surface have Zn-O distances of 1.97(.02) Å and coordination numbers of about 4.0(0.5), consistent with tetrahedral oxygen coordination. This contrasts with Zn-O distances of 2.11(.02) Å and coordination numbers of 6 to 7 in the aqueous Zn solutions used in sample preparation. X-ray absorption extended fine structure spectroscopy (EXAFS) fits to the second shell of cation neighbors indicate as many as 4 Zn-Fe neighbors at 3.44(.04) Å in coprecipitated samples, and about two Zn-Fe neighbors at the same distance in adsorption samples. In both sets of samples, the fitted coordination number of second shell cations decreases as sorption density increases, indicating changes in the number and type of available complexing sites or the onset of competitive precipitation processes. Comparison of our results with the possible geometries for surface complexes and precipitates suggests that the Zn sorption complexes are inner sphere and at lowest adsorption densities are bidentate, sharing apical oxygens with adjacent edge-sharing Fe(O,OH)6 octahedra. Coprecipitation samples have complexes with similar geometry, but these are polydentate, sharing apices with more than two adjacent edge-sharing Fe(O,OH)6 polyhedra. The results are inconsistent with Zn entering the ferrihydrite structure (i.e., solid solution formation) or formation of other Zn-Fe precipitates. The fitted Zn-Fe coordination numbers drop with increasing Zn density with a minimum of about 0.8(.2) at Zn/(Zn + Fe) of 0.08 or more. This change appears to be attributable to the onset of precipitation of zinc hydroxide polymers with mainly tetrahedral Zn coordination. At the highest loadings studied, the nature of the complexes changes further, and a second type of precipitate forms. This has a structure based on a brucite layer topology, with mainly octahedral Zn coordination. Amorphous zinc hydroxide samples prepared for comparison had a closely similar local structure. Analysis of the Fe K-edge EXAFS is consistent with surface complexation reactions and surface precipitation at high Zn loadings with little or no Fe-Zn solid solution formation. The formation of Zn-containing precipitates at solution conditions two or more orders of magnitude below their solubility limit is compared with other sorption and spectroscopic studies that describe similar behavior.

G.A Waychunas; C.C Fuller; J.A Davis

2002-01-01T23:59:59.000Z

78

In Situ X-ray Near-Edge Absorption Spectroscopy Investigation of the State of Charge of All-Vanadium Redox Flow Batteries  

Science Journals Connector (OSTI)

all-vanadium flow battery; X-ray near-edge adsorption spectroscopy; synchrotron; in situ; state of charge; electrolyte ... Among different types of RFBs, the all-vanadium redox flow battery (VRB) displays excellent electrochemical activity and reversibility. ... To the best of our knowledge, this is the first report to use the in situ synchrotron techniques to study the redox flow battery. ...

Chuankun Jia; Qi Liu; Cheng-Jun Sun; Fan Yang; Yang Ren; Steve M. Heald; Yadong Liu; Zhe-Fei Li; Wenquan Lu; Jian Xie

2014-09-05T23:59:59.000Z

79

Structure of the c(22) coverage of Cl on Ag(100): A controversy resolved by surface extended x-ray-absorption fine-structure spectroscopy  

Science Journals Connector (OSTI)

By performing surface extended x-ray-absorption fine-structure measurements, we have resolved the discrepancies between previously reported results for the adsorbate-substrate bond length in Ag(100)c(2×2)-Cl. The Cl atoms form a simple overlayer occupying the fourfold hollows of the silver surface with a Cl-Ag distance of 2.69±0.03 A?, in agreement with a published low-energy electron diffraction study, though with greater precision.

G. M. Lamble, R. S. Brooks, J. C. Campuzano, D. A. King, and D. Norman

1987-07-15T23:59:59.000Z

80

Quick-scanning x-ray absorption spectroscopy system with a servo-motor-driven channel-cut monochromator with a temporal resolution of 10 ms  

SciTech Connect

We have developed a quick-scanning x-ray absorption fine structure (QXAFS) system and installed it at the recently constructed synchrotron radiation beamline BL33XU at the SPring-8. Rapid acquisition of high-quality QXAFS data was realized by combining a servo-motor-driven Si channel-cut monochromator with a tapered undulator. Two tandemly aligned monochromators with channel-cut Si(111) and Si(220) crystals covered energy ranges of 4.0-28.2 keV and 6.6-46.0 keV, respectively. The system allows the users to adjust instantly the energy ranges of scans, the starting angles of oscillations, and the frequencies. The channel-cut crystals are cooled with liquid nitrogen to enable them to withstand the high heat load from the undulator radiation. Deformation of the reflecting planes is reduced by clamping each crystal with two cooling blocks. Performance tests at the Cu K-edge demonstrated sufficiently high data quality for x-ray absorption near-edge structure and extended x-ray absorption fine-structure analyses with temporal resolutions of up to 10 and 25 ms, respectively.

Nonaka, T.; Dohmae, K.; Araki, T.; Hayashi, Y.; Hirose, Y. [Toyota Central R and D Labs., Inc., Nagakute, Aichi 480-1192 (Japan); Uruga, T.; Yamazaki, H.; Tanida, H.; Goto, S. [JASRI/Spring-8, 1-1-1, Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5198 (Japan); Mochizuki, T. [JASRI/Spring-8, 1-1-1, Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5198 (Japan); Toyama Corp., Zama, Kanagawa 228-0003 (Japan)

2012-08-15T23:59:59.000Z

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


81

X-Ray Photoelectron Spectroscopy XPS Mark Engelhard  

E-Print Network (OSTI)

X-Ray Photoelectron Spectroscopy XPS Mark Engelhard 1 #12;EMSL XPS Instrumentation 2 Physical Electronics Quantera XPS High Energy Resolution Focused X-ray Beam Capability Catalysis reaction and processing chamber with inert atmosphere glove box connected to a PHI Quantera Scanning X-ray Microprobe

82

XRMS: X-Ray Spectroscopy of Magnetic Solids  

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

XRMS: X-Ray Spectroscopy of Magnetic Solids October 22-23, 2011 SLAC National Accelerator Laboratory, Menlo Park, CA More information...

83

Synchrotron x-ray fluorescence and extended x-ray absorption fine structure analysis  

SciTech Connect

The advent of dedicated synchrotron radiation sources has led to a significant increase in activity in many areas of science dealing with the interaction of x-rays with matter. Synchrotron radiation provides intense, linearly polarized, naturally collimated, continuously tunable photon beams, which are used to determine not only the elemental composition of a complex, polyatomic, dilute material but also the chemical form of the elements with improved accuracy. Examples of the application of synchrotron radiation include experiments in synchrotron x-ray fluorescence (SXRF) analysis and extended x-ray absorption fine structure (EXAFS) analysis. New synchrotron radiation x-ray microprobes for elemental analysis in the parts per billion range are under construction at several laboratories. 76 references, 24 figures.

Chen, J.R.; Gordon, B.M.; Hanson, A.L.; Jones, K.W.; Kraner, H.W.; Chao, E.C.T.; Minkin, J.A.

1984-01-01T23:59:59.000Z

84

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

SciTech Connect

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.

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

2010-03-31T23:59:59.000Z

85

Core Level Spectroscopies Surface Science and X-Ray Spectroscopy Group  

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

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

86

X-ray Spectroscopy of Cooling Cluster  

SciTech Connect

We review the X-ray spectra of the cores of clusters of galaxies. Recent high resolution X-ray spectroscopic observations have demonstrated a severe deficit of emission at the lowest X-ray temperatures as compared to that expected from simple radiative cooling models. The same observations have provided compelling evidence that the gas in the cores is cooling below half the maximum temperature. We review these results, discuss physical models of cooling clusters, and describe the X-ray instrumentation and analysis techniques used to make these observations. We discuss several viable mechanisms designed to cancel or distort the expected process of X-ray cluster cooling.

Peterson, J.R.; /SLAC; Fabian, A.C.; /Cambridge U., Inst. of Astron.

2006-01-17T23:59:59.000Z

87

X-ray Spectroscopy of Cooling Clusters  

E-Print Network (OSTI)

We review the X-ray spectra of the cores of clusters of galaxies. Recent high resolution X-ray spectroscopic observations have demonstrated a severe deficit of emission at the lowest X-ray temperatures as compared to that expected from simple radiative cooling models. The same observations have provided compelling evidence that the gas in the cores is cooling below half the maximum temperature. We review these results, discuss physical models of cooling clusters, and describe the X-ray instrumentation and analysis techniques used to make these observations. We discuss several viable mechanisms designed to cancel or distort the expected process of X-ray cluster cooling.

J. R. Peterson; A. C. Fabian

2005-12-21T23:59:59.000Z

88

X-ray bandwidth: Determination by on-edge absorption and effect on various absorption experiments  

E-Print Network (OSTI)

X-ray bandwidth: Determination by on-edge absorption and effect on various absorption experiments of an x-ray source is increasingly important in fundamental experi- ments and critical applications. The bandwidth of an x-ray beam, selected from a synchrotron radiation spectrum for example, ultimately defines

Chantler, Christopher T.

89

X-Ray Photoelectron Spectroscopy (XPS) Applied to Soot & What...  

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

Photoelectron Spectroscopy (XPS) Applied to Soot & What It Can Do for You X-Ray Photoelectron Spectroscopy (XPS) Applied to Soot & What It Can Do for You Presentation given at DEER...

90

Simulating Cl K-edge X-ray absorption spectroscopy in MCl62- (M= U, Np, Pu) complexes and UOCl5- using time-dependent density functional theory  

SciTech Connect

We report simulations of the X-ray absorption near edge structure (XANES) at the Cl K-edge of actinide hexahalides MCl62- (M = U, Np, Pu) and the UOCl5- complex using linear-response time-dependent density functional theory (LR-TDDFT) extended for core excitations. To the best of our knowledge, these are the first calculations of the Cl K-edge spectra of NpCl62- and PuCl62-. In addition, the spectra are simulated with and without the environmental effects of the host crystal as well as ab initio molecular dynamics (AIMD) to capture the dynamical effects due to atomic motion. The calculated spectra are compared with experimental results, where available and the observed trends are discussed.

Govind, Niranjan; De Jong, Wibe A.

2014-02-21T23:59:59.000Z

91

X-ray absorption and resonant x-ray emission spectra by electric quadrupole excitation in light rare-earth systems  

Science Journals Connector (OSTI)

We have made precise theoretical calculations for both 2p3/2?4f x-ray absorption spectra and 3d?2p3/2 resonant x-ray emission spectra involving electric quadrupole excitations at the L3 edge of light rare-earth elements from La to Eu. It is shown that the energy separation of a double-peak structure observed by x-ray absorption spectroscopy (XAS) does not agree with that determined from resonant x-ray emission spectroscopy (RXES), in contrast to recent experimental results by Bartolomé et al. The reason for this difference is that the energy separation in XAS is determined by the 4f-4f interaction only, while that in RXES is determined by both 4f-4f and 3d-4f interactions.

M. Nakazawa; K. Fukui; H. Ogasawara; A. Kotani; C. F. Hague

2002-09-26T23:59:59.000Z

92

X-ray absorption anisotropy for polychromatic illumination--Crystal views from inside  

E-Print Network (OSTI)

X-ray absorption anisotropy for polychromatic illumination--Crystal views from inside P. Korecki a Keywords: X-ray absorption Real-space imaging X-ray holography Electron channeling Electron backscatter of the fine structure in X-ray absorption anisotropy, which results from incident beam diffraction

Korecki, Pawe³

93

Soft X-Ray Microscopy and Spectroscopy at the Molecular Environmental...  

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

Soft X-Ray Microscopy and Spectroscopy at the Molecular Environmental Science Beamline at the Advanced Light Source. Soft X-Ray Microscopy and Spectroscopy at the Molecular...

94

Beyond hard x-ray photoelectron spectroscopy: Simultaneous combination with x-ray diffraction  

SciTech Connect

Hard x-ray photoelectron spectroscopy (HAXPES) is a powerful and novel emerging technique for the nondestructive determination of electronic properties and chemical composition of bulk, buried interfaces and surfaces. It benefits from the exceptionally large escape depth of high kinetic energy photoelectrons, increasing the information depth up to several tens of nanometers. Complementing HAXPES with an atomic structure sensitive technique (such as x-ray diffraction) opens a new research field with major applications for materials science. At SpLine, the Spanish CRG beamline at the European Synchrotron Radiation Facility, we have developed a novel experimental set-up that combines HAXPES and x-ray diffraction (x-ray reflectivity, surface x-ray diffraction, grazing incidence x-ray diffraction, and reciprocal space maps). Both techniques can be operated simultaneously on the same sample and using the same excitation source. The set-up includes a robust 2S + 3D diffractometer hosting a ultrahigh vacuum chamber equipped with a unique photoelectron spectrometer (few eV < electron kinetic energy < 15 keV), x-ray tube (Mg/Ti), 15 keV electron gun, and auxiliary standard surface facilities (molecular beam epitaxy evaporator, ion gun, low energy electron diffraction, sample heating/cooling system, leak valves, load-lock sample transfer, etc.). This end-station offers the unique possibility of performing simultaneous HAXPES + x-ray diffraction studies. In the present work, we describe the experimental set-up together with two experimental examples that emphasize its outstanding capabilities: (i) nondestructive characterization of the Si/Ge and HfO{sub 2}/SiO{sub 2} interfaces on Ge-based CMOS devices, and (ii) strain study on La{sub 0.7}Ca{sub 0.3}MnO{sub 3} ultrathin films grown on SrTiO{sub 3}(001) substrate.

Rubio-Zuazo, Juan; Castro, German R. [SpLine, Spanish CRG beamline at the European Synchrotron Radiation Facility, B.P. 220, F-38043 Grenoble (France) and ICMM-CSIC Cantoblanco, E-28049 Madrid (Spain)

2013-05-15T23:59:59.000Z

95

An in-situ cell for characterization of solids by soft X-ray absorption  

E-Print Network (OSTI)

Scientific Instruments a Absorption (a.u. ) b d 0.01 abs cJ. Lynch, in X-ray Absorption Fine Structure for Catalysts18, pp. 431-512. X-ray Absorption: Principles, Applications,

2007-01-01T23:59:59.000Z

96

Superconductivity suppression of R(Ba1-zRz)2Cu3O7+? (R=Nd, Pr) probed by soft-x-ray absorption spectroscopy  

Science Journals Connector (OSTI)

O K-edge x-ray-absorption near-edge-structure (XANES) spectra of (Nd1-xPrx)1.05Ba1.95Cu3O7 for x=0–0.5 and Nd1.05(Ba1-zPrz)1.95Cu3O7+? for z=0–0.25 were performed to search for microstructural features and hole distribution related to the superconducting properties. Near the O 1s edge, prepeaks at ?527.6 and ?528.3 eV are assigned to transitions into O 2p holes located in the CuO3 ribbons and CuO2 planes, respectively. As deduced from O 1s absorption spectra of (Nd1-xPrx)1.05Ba1.95Cu3O7 for x=0–0.5, the hole concentrations in the CuO2 planes and CuO3 ribbons decrease monotonically with increasing Pr doping. The present XANES results clearly reveal that the suppression of superconductivity with Pr doping in (Nd1-xPrx)1.05Ba1.95Cu3O7 results predominantly from the hole depletion effect. The effect of Pr on the Ba site in Nd1.05(Ba1-zPrz)1.95Cu3O7+? is to reduce the hole concentration in the CuO2 planes and to create localized fivefold Cu chain sites. Tc of Nd1.05(Ba1-zPrz)1.95Cu3O7+? is depressed upon Pr doping, primarily due to hole filling and hole localization. Compared to (Nd1-xPrx)1.05Ba1.95Cu3O7, the enhanced suppression of Tc in Nd1.05(Ba1-zPrz)1.95Cu3O7+? is primarily due to the hole localization.

J. M. Chen; R. S. Liu; P. Nachimuthu; M. J. Kramer; K. W. Dennis; R. W. McCallum

1999-02-01T23:59:59.000Z

97

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

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

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

98

A high-resolution large-acceptance analyzer for X-ray fluorescence and Raman spectroscopy  

SciTech Connect

A newly designed multi-crystal X-ray spectrometer and its applications in the fields of X-ray fluorescence and X-ray Raman spectroscopy are described. The instrument is based on 8 spherically curved Si crystals, each with a 3.5 inch diameter form bent to a radius of 86 cm. The crystals are individually aligned in the Rowland geometry capturing a total solid angle of 0.07 sr. The array is arranged in a way that energy scans can be performed by moving the whole instrument, rather than scanning each crystal by itself. At angles close to back scattering the energy resolution is between 0.3 and 1 eV depending on the beam dimensions at the sample. The instrument is mainly designed for X-ray absorption and fluorescence spectroscopy of transition metals in dilute systems such as metalloproteins. First results of the Mn K{beta} (3p -> 1s) emission in photosystem II are shown. An independent application of the instrument is the technique of X-ray Raman spectroscopy which can address problems similar to those in traditional soft X-ray absorption spectroscopies, and initial results are presented.

Bergmann, Uwe; Cramer, Stephen P.

2001-08-02T23:59:59.000Z

99

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

E-Print Network (OSTI)

range requires the use of UHV instrumentation. However byseparate the samples from the UHV environment, soft x-rays1c) of the cell was made of a UHV compatible and chemically

Jiang, Peng

2010-01-01T23:59:59.000Z

100

X-ray Photoelectron Spectroscopy (XPS) | EMSL  

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

photoelectron spectroscopy (UPS), ion scattering spectroscopy (ISS), a clusterAr+ ion gun, and a five-axis automated stage with variable temperature sample environment at the...

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


101

Ultrafast conversions between hydrogen bonded structures in liquid water observed by femtosecond x-ray spectroscopy  

SciTech Connect

We present the first femtosecond soft x-ray spectroscopy in liquids, enabling the observation of changes in hydrogen bond structures in water via core-hole excitation. The oxygen K-edge of vibrationally excited water is probed with femtosecond soft x-ray pulses, exploiting the relation between different water structures and distinct x-ray spectral features. After excitation of the intramolecular OH stretching vibration, characteristic x-ray absorption changes monitor the conversion of strongly hydrogen-bonded water structures to more disordered structures with weaker hydrogen-bonding described by a single subpicosecond time constant. The latter describes the thermalization time of vibrational excitations and defines the characteristic maximum rate with which nonequilibrium populations of more strongly hydrogen-bonded water structures convert to less-bonded ones. On short time scales, the relaxation of vibrational excitations leads to a transient high-pressure state and a transient absorption spectrum different from that of statically heated water.

Wen, Haidan; Huse, Nils; Schoenlein, Robert W.; Lindenberg, Aaron M.

2010-05-01T23:59:59.000Z

102

Reverse Monte Carlo analysis of the local order in liquid Ge{sub 0.15}Te{sub 0.85} alloys combining neutron scattering and x-ray absorption spectroscopy  

SciTech Connect

The structure of liquid Ge{sub 0.15}Te{sub 0.85} alloys that exhibit a density anomaly between 633 K and 733 K at ambient pressure was investigated using x-ray absorption spectroscopy at the Ge K edge. Using a reverse Monte Carlo method to combine the present results with neutron scattering data, we show that the volume contraction is associated with an increase of the first neighbor coordination number around both Ge and Te by about one atom. The coordination number of Ge increases from 3{+-}0.3 to 4.1{+-}0.3. These results support an interpretation of the density anomaly in terms of the same Peierls-like distortion mechanism acting in the liquid state and in the neighboring (pure Te and GeTe compound) phases.

Coulet, Marie-Vanessa; Testemale, Denis; Hazemann, Jean-Louis; Gaspard, Jean-Pierre; Bichara, Christophe [Laboratoire TECSEN, UMR 6122, CNRS-Universite Paul Cezanne, Campus de St Jerome, 13397 Marseille Cedex 20 (France); SNBL/ESRF, 6 rue Jules Horowitz, Boite Postale 220, 38043, Grenoble (France); Laboratoire de Cristallographie, 25 Avenue des Martyrs, Boite Postale 166, 38043 Grenoble (France) and European Synchroton Radiation Facility, 6 rue Jules Horowitz, Boite Postale 220, 38043 Grenoble (France); Physique de la Matiere Condensee, B5, Universite de Liege, B4000 Sart-Tilman (Belgium); Centre de Recherches en Matiere Condensee et Nanosciences-CNRS, Campus de Luminy, Case 913, F13288 Marseille (France)

2005-11-01T23:59:59.000Z

103

Origin of improved scintillation efficiency in (Lu,Gd){sub 3}(Ga,Al){sub 5}O{sub 12}:Ce multicomponent garnets: An X-ray absorption near edge spectroscopy study  

SciTech Connect

In the recent successful improvement of scintillation efficiency in Lu{sub 3}Al{sub 5}O{sub 12}:Ce driven by Ga{sup 3+} and Gd{sup 3+} admixture, the “band-gap engineering” and energy level positioning have been considered the valid strategies so far. This study revealed that this improvement was also associated with the cerium valence instability along with the changes of chemical composition. By utilizing X-ray absorption near edge spectroscopy technique, tuning the Ce{sup 3+}/Ce{sup 4+} ratio by Ga{sup 3+} admixture was evidenced, while it was kept nearly stable with the Gd{sup 3+} admixture. Ce valence instability and Ce{sup 3+}/Ce{sup 4+} ratio in multicomponent garnets can be driven by the energy separation between 4f ground state of Ce{sup 3+} and Fermi level.

Wu, Yuntao, E-mail: caswyt@hotmail.com; Luo, Jialiang; Ren, Guohao [Shanghai Institute of Ceramics, Chinese Academy of Sciences, No.215 Road, Jiading, Shanghai 201899 (China); Nikl, Martin [Institute of Physics, Academy of Sciences of the Czech Republic, Cukrovarnická 10, 16253 Prague 6 (Czech Republic)

2014-01-01T23:59:59.000Z

104

Accepted Manuscript Laboratory-based recording of holographic fine structure in x-ray absorption  

E-Print Network (OSTI)

be only performed using synchrotron radiation. Keywords: x-ray absorption, atomic structure, xAccepted Manuscript Laboratory-based recording of holographic fine structure in x-ray absorption structure in x-ray absorption anisotropy using polycapillary optics, Nucl. Instr. and Meth. in Phys. Res. B

Korecki, Pawe³

105

Directional fine structure in absorption of white x rays: A tomographic interpretation P. Korecki,1,  

E-Print Network (OSTI)

structure in absorption of white x rays can be interpreted as real-space projections of atomic structure from neigh- boring atoms.1 A straightforward analysis of the extended x-ray absorption fine structure of the absorbing atoms. Thus, the absorption cross section is effectively modulated by the x-ray scattering

Korecki, Pawe³

106

X-RAY ABSORPTION OF HIGH-REDSHIFT QUASARS  

SciTech Connect

The soft X-ray photoelectric absorption of high-z quasars has been known for two decades, but has no unambiguous astrophysical context. We construct the largest sample to date of 58 high-redshift quasars (z > 0.45) selected from the XMM-Newton archive based on a high photon count criterion (>1800). We measure the optical depth {tau} at 0.5 keV and find that 43% of the quasars show significant absorption. We aim to find which physical parameters of the quasars, e.g., redshift, radio luminosity, radio loudness, or X-ray luminosity, drive their observed absorption. We compare the absorption behavior with redshift with the pattern expected if the diffuse intergalactic medium (IGM) is responsible for the observed absorption. We also compare the absorption with a comparison sample of gamma-ray burst (GRB) X-ray afterglows. Although the z > 2 quasar opacity is consistent with diffuse IGM absorption, many intermediate-z (0.45 < z < 2) quasars are not sufficiently absorbed for this scenario, and are appreciably less absorbed than GRBs. Only 10/37 quasars at z < 2 are absorbed, and only 5/30 radio-quiet quasars are absorbed. We find a weak correlation between {tau} and z, and an even weaker correlation between {tau} and radio luminosity. These findings lead to the conclusion that although a diffuse IGM origin for the quasar absorption is unlikely, the optical depth does seem to increase with redshift, roughly as (1 + z){sup 2.2{+-}0.6}, tending to {tau} Almost-Equal-To 0.4 at high redshifts, similar to the high-z GRBs. This result can be explained by an ionized and clumpy IGM at z < 2, and a cold, diffuse IGM at higher redshift. If, conversely, the absorption occurs at the quasar, and owing to the steep L{sub x} {proportional_to}(1 + z){sup 7.1{+-}0.5} correlation in the present sample, the host column density scales as N{sub H}{proportional_to}L{sub x}{sup 0.7{+-}0.1}.

Eitan, Assaf; Behar, Ehud, E-mail: sassafe@tx.technion.ac.il, E-mail: behar@physics.technion.ac.il [Physics Department, Technion, Haifa 32000 (Israel)

2013-09-01T23:59:59.000Z

107

Pixel detectors for x-ray imaging spectroscopy in space  

Science Journals Connector (OSTI)

Pixelated semiconductor detectors for X-ray imaging spectroscopy are foreseen as key components of the payload of various future space missions exploring the x-ray sky. Located on the platform of the new Spectrum-Roentgen-Gamma satellite, the eROSITA (extended Roentgen Survey with an Imaging Telescope Array) instrument will perform an imaging all-sky survey up to an X-ray energy of 10 keV with unprecedented spectral and angular resolution. The instrument will consist of seven parallel oriented mirror modules each having its own pnCCD camera in the focus. The satellite born X-ray observatory SIMBOL-X will be the first mission to use formation-flying techniques to implement an X-ray telescope with an unprecedented focal length of around 20 m. The detector instrumentation consists of separate high- and low energy detectors, a monolithic 128 ? 128 DEPFET macropixel array and a pixellated CdZTe detector respectively, making energy band between 0.5 to 80 keV accessible. A similar concept is proposed for the next generation X-ray observatory IXO. Finally, the MIXS (Mercury Imaging X-ray Spectrometer) instrument on the European Mercury exploration mission BepiColombo will use DEPFET macropixel arrays together with a small X-ray telescope to perform a spatially resolved planetary XRF analysis of Mercury's crust. Here, the mission concepts and their scientific targets are briefly discussed, and the resulting requirements on the detector devices together with the implementation strategies are shown.

J Treis; R Andritschke; R Hartmann; S Herrmann; P Holl; T Lauf; P Lechner; G Lutz; N Meidinger; M Porro; R H Richter; F Schopper; H Soltau; L Strüder

2009-01-01T23:59:59.000Z

108

Single atom identification by energy dispersive x-ray spectroscopy  

SciTech Connect

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

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

2012-04-09T23:59:59.000Z

109

SSRL School on Synchrotron X-ray Spectroscopy Techniques in Environmental  

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

Home Home Agenda Location Visitor Information Transportation Tourism & Dining SSRL School on Synchrotron X-ray Spectroscopy Techniques in Environmental and Materials Sciences: Theory and Application June 2-5, 2009 Group photo of the attendees at the SSRL School on X-ray Spectropscopy Techniques in Environmental and Materials Sciences: Theory and Application held June 2-5, 2009 at the Stanford Synchrotron Radiation Lightsource. » View photos from XAS 2009 Overview: Modern synchrotron radiation based X-ray absorption spectroscopy (SR-XAS) techniques offer the ability to probe local molecular scale physical and electronic structures that govern key properties of technological and environmental materials and molecular complexes. The high collimation, intensity, and tunability of SR allow the investigation of a wide range of materials, including thin films and interfaces, nanoparticles, amorphous materials, solutions, hydrated and disordered bacteriogenic minerals, soils, interfaces, and dissolved species.

110

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

SciTech Connect

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.

Wang, Xin [Univ. of California, Davis, CA (United States). Dept. of Applied Science]|[Lawrence Berkeley National Lab., CA (United States)

1996-12-01T23:59:59.000Z

111

X-ray absorption spectroscopic studies of mononuclear non-heme iron enzymes  

SciTech Connect

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.

Westre, T.E.

1996-01-01T23:59:59.000Z

112

X-ray spectroscopy of neutron star low-mass X-ray binaries  

E-Print Network (OSTI)

In this thesis, I present work spanning a variety of topics relating to neutron star lowmass X-ray binaries (LMXBs) and utilize spectral information from X-ray observations to further our understanding of these sources. ...

Krauss, Miriam Ilana

2007-01-01T23:59:59.000Z

113

High-Resolution Structure of the Photosynthetic Mn4Ca Catalyst from X-ray Spectroscopy  

SciTech Connect

The application of high-resolution X-ray spectroscopy methods to study the photosynthetic water oxidizing complex, which contains a unique hetero-nuclear catalytic Mn4Ca cluster, are described. Issues of X-ray damage especially at the metal sites in the Mn4Ca cluster are discussed. The structure of the Mn4Ca catalyst at high-resolution which has so far eluded attempts of determination by X-ray diffraction, EXAFS and other spectroscopic techniques has been addressed using polarized EXAFS techniques applied to oriented PS II membrane preparations and PS II single crystals. A review of how the resolution of traditional EXAFS techniques can be improved, using methods such as range-extended EXAFS is presented, and the changes that occur in the structure of the cluster as it advances through the catalytic cycle are described. X-ray absorption and emission techniques (XANES and K? emission) have been used earlier to determine the oxidation states of the Mn4Ca cluster, and in this report we review the use of X-ray resonant Raman spectroscopy to understand the electronic structure of the Mn4Ca cluster as it cycles through the intermediate S-states.

Yachandra, Vittal; Yano, Junko; Kern, Jan; Pushkar, Yulia; Sauer, Kenneth; Glatzel, Pieter; Bergmann, Uwe; Messinger, Johannes; Zouni, Athina; Yachandra, Vittal K.

2007-08-01T23:59:59.000Z

114

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

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.

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

2009-05-28T23:59:59.000Z

115

New Developments in Femtosecond Soft X-ray Spectroscopy  

SciTech Connect

Recent instrumentation developments in X-ray spectroscopy for ultra-fast time-resolved measurements with soft X-rays done in HZB Berlin during the last years are described. The significant performance improvements achieved this way are based on Fresnel diffraction from structures being fabricated on a surface of a total externally reflecting mirror. The first type of this spectrometer, an off-axis reflection zone plate, has been implemented at the BESSY Femtoslicing setup and shows on the order of 20 times higher flux in the focal plane compared to the classical grating monochromator beamline. It has proven to serve very precise experiments with a time resolution down to 100 fs on magnetic materials after optical laser pulse excitation.

Erko, A.; Firsov, A.; Holldack, K. [Helmholtz-Zentrum Berlin fuer Materialien und Energie GmbH, Elektronenspeicherring BESSY II, Albert Einstein str.15, Berlin (Germany)

2010-06-23T23:59:59.000Z

116

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

SciTech Connect

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

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

2010-12-01T23:59:59.000Z

117

Picosecond x-ray absorption measurements of the ligand substitution dynamics of Fe(CO){sub 5} in ethanol.  

SciTech Connect

Ultrafast X-ray absorption near edge spectroscopy has been carried out for photo excited iron pentacarbonyl in ethanol with 2 picosecond resolution. A temporal resolution limited dissociation process was observed, followed by the formation of the mono-substituted complex Fe(CO){sub 4}EtOH within a few tens of picoseconds. The measurements have been carried out with a newly developed X-ray absorption instrument at station 7 ID-C of the Advanced Photon Source. The results show that single picosecond temporal resolution can be achieved at a synchrotron beam line.

Ahr, B.; Chollet, M.; Adams, B.; Lunny, E. M.; Laperie, C. M.; Rose-Petruck, C. (X-Ray Science Division); (Brown Univ.); (Providence Coll.)

2011-01-01T23:59:59.000Z

118

X-ray photon correlation spectroscopy under flow  

E-Print Network (OSTI)

X-ray photon correlation spectroscopy was used to probe the diffusive dynamics of colloidal particles in a shear flow. Combining X-ray techniques with microfluidics is an experimental strategy that reduces the risk of x-ray induced beam damage and also allows time-resolved studies of processes taking place in flowcells. The experimental results and theoretical predictions presented here, show that in the low shear limit, for a ``transverse flow'' scattering geometry (scattering wave vector q perpendicular to the direction of flow) the measured relaxation times are independent of the flow rate and determined only by the diffusive motion of the particles. This is not generally valid and in particular, for a ``longitudinal flow'' (q || flow) scattering geometry, the relaxation times are strongly affected by the flow-induced motion of the particles. Our results show that the Brownian diffusion of colloidal particles can be measured in a flowing sample and that, up to flux limitations, the experimental conditions under which this is possible are easier to achieve at higher values of q.

Andrei Fluerasu; Abdellatif Moussaid; Henri Gleyzolle; Peter Falus; Anders Madsen

2008-03-10T23:59:59.000Z

119

Core and Valence Excitations in Resonant X-ray Spectroscopy using Restricted Excitation Window Time-dependent Density Functional Theory  

SciTech Connect

We report simulations of X-ray absorption near edge structure (XANES), resonant inelastic X-ray scattering (RIXS) and 1D stimulated X-ray Raman spectroscopy (SXRS) signals of cysteine at the oxygen, nitrogen and sulfur K and L2,3 edges. The simulated XANES signals from the restricted window time-dependent density functional theory (REW-TDDFT) and the static exchange (STEX) method are compared with experiments, showing that REW-TDDFT is more accurate and computationally less expensive than STEX. Simulated RIXS and 1D SXRS signals from REW-TDDFT give some insights on the correlation of different excitations in the molecule.

Zhang, Yu; Biggs, Jason D.; Healion, Daniel; Govind, Niranjan; Mukamel, Shaul

2012-11-21T23:59:59.000Z

120

Chandra X-ray Observations of NGC 4258: Iron Absorption Lines from the Nucleus  

E-Print Network (OSTI)

We report sub-arcsecond resolution X-ray imaging spectroscopy of the low luminosity active galactic nucleus of NGC 4258 and its immediate surroundings with the Chandra X-ray Observatory. NGC 4258 was observed four times, with the first two observations separated by one month, followed over a year later by two consecutive observations. The spectrum of the nucleus is well described by a heavily absorbed, hard X-ray power law of variable luminosity, plus a constant, thermal soft X-ray component. We do not detect an iron K alpha emission line with the upper limit to the equivalent width of a narrow, neutral iron line ranging between 94 and 887 eV (90% confidence) for the different observations. During the second observation on 2000-04-17, two narrow absorption features are seen with >99.5% confidence at ~6.4 keV and ~6.9 keV, which we identify as resonant absorption lines of Fe XVIII - Fe XIX K alpha and Fe XXVI K alpha, respectively. In addition, the 6.9 keV absorption line is probably variable on a timescale of ~6000 sec. The absorption lines are analyzed through a curve of growth analysis, which allows the relationship between ionic column and kinematic temperature or velocity dispersion to be obtained for the observed equivalent widths. We discuss the properties of the absorbing gas for both photo and collisionally ionized models. Given that the maser disk is viewed at an inclination i = 82 degrees, the gas responsible for the 6.9 keV absorption line may be in an inner disk, a disk-wind boundary layer or be thermal gas entrained at the base of the jet. The gas which gives rise to the photoelectric absorption may be the same as that which causes the 6.4 keV Fe K alpha absorption provided that the gas has a bulk velocity dispersion of a few thousand km/s. (Abstract abridged).

A. J. Young; A. S. Wilson

2003-10-20T23:59:59.000Z

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


121

3D Imaging of Nickel Oxidation States using Full Field X-ray Absorption Near Edge Structure Nanotomography  

SciTech Connect

Reduction-oxidation (redox) cycling of the nickel electrocatalyst phase in the solid oxide fuel cell (SOFC) anode can lead to performance degradation and cell failure. A greater understanding of nickel redox mechanisms at the microstructural level is vital to future SOFC development. Transmission x-ray microscopy (TXM) provides several key techniques for exploring oxidation states within SOFC electrode microstructure. Specifically, x-ray nanotomography and x-ray absorption near edge structure (XANES) spectroscopy have been applied to study samples of varying nickel (Ni) and nickel oxide (NiO) compositions. The imaged samples are treated as mock SOFC anodes containing distinct regions of the materials in question. XANES spectra presented for the individual materials provide a basis for the further processing and analysis of mixed samples. Images of composite samples obtained are segmented, and the distinct nickel and nickel oxide phases are uniquely identified using full field XANES spectroscopy. Applications to SOFC analysis are discussed.

Nelson, George; Harris, William; Izzo, John; Grew, Kyle N. (Connecticut); (USARL)

2012-01-20T23:59:59.000Z

122

Ligand effects on the X-ray absorption of a nickel porphyrin complex: a simulation study  

E-Print Network (OSTI)

.elsevier.com/locate/chemphys #12;where W l PP stands for the atomic absorption spectrum for the lth site: W l PP ¼ 1 2 1 X2 x R ZLigand effects on the X-ray absorption of a nickel porphyrin complex: a simulation study Luke Abstract We present a simulation of the X-ray absorption near-edge spectrum (XANES) of the metal porphyrin

Mukamel, Shaul

123

Laboratory-based recording of holographic fine structure in X-ray absorption anisotropy using polycapillary optics  

E-Print Network (OSTI)

10 April 2012 Available online 17 May 2012 Keywords: X-ray absorption Atomic structure XLaboratory-based recording of holographic fine structure in X-ray absorption anisotropy using) was characterized and used for recording two-dimensional maps of X-ray absorption anisotropy (XAA). XAA originates

Korecki, Pawe³

124

Improved self-absorption correction for extended x-ray absorption fine-structure measurements  

SciTech Connect

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.

Booth, C.H.; Bridges, F.

2003-06-04T23:59:59.000Z

125

E-Print Network 3.0 - angle x-ray absorption Sample Search Results  

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

FROM PLANETS AND COMETS: RELATIONSHIP WITH SOLAR X-RAYS AND SOLAR WIND Summary: in the atomic and molecular constituents of the atmosphere, and 2) the absorption of incident...

126

X-ray magnetic circular dichroism in (Ge,Mn) compounds: experiments and modeling Samuel Tardif,1, 2,  

E-Print Network (OSTI)

X-ray magnetic circular dichroism in (Ge,Mn) compounds: experiments and modeling Samuel Tardif,1, 2: July 29, 2013) X-ray absorption (XAS) and x-ray magnetic circular dichroism (XMCD) spectra at the L2),6 and x-ray spectroscopy (x-ray absorption spec- troscopy, XAS, and x-ray magnetic circular

127

Electronic states of NO{sub 2}-exposed H-terminated diamond/Al{sub 2}O{sub 3} heterointerface studied by synchrotron radiation photoemission and X-ray absorption spectroscopy  

SciTech Connect

The energy band-lineup and the electronic structure of NO{sub 2}-exposed H-terminated diamond/Al{sub 2}O{sub 3} heterointerface have been investigated by synchrotron radiation photoemission and x-ray absorption near-edge structure (XANES) measurements. It is found that the energy band-lineup is stagger-type, so-called type-II, with its valence band discontinuity of as high as 3.9?eV and its conduction band discontinuity of 2.7?eV. The valence band maximum of the H-terminated diamond surface is positioned at Fermi level as a result of high-density hole accumulation on the diamond side. The XANES measurement has shown that the oxygen-derived interface state locates at about 1–3?eV above the Fermi level.

Takahashi, Kazutoshi; Imamura, Masaki [Synchrotron Light Application Center, Saga University, Saga 840-8502 (Japan); Hirama, Kazuyuki [NTT Basic Research Laboratories, NTT Corporation, Atsugi 243-0198 (Japan); Kasu, Makoto [Department of Electrical and Electronic Engineering, Saga University, Saga 840-8502 (Japan)

2014-02-17T23:59:59.000Z

128

Spatially Resolved X-ray Spectroscopy of Vela Shrapnel A  

E-Print Network (OSTI)

We present the detailed X-ray spectroscopy of Vela shrapnel A with the XMM-Newton satellite. Vela shrapnel A is one of several protrusions identified as bullets from Vela supernova explosion. The XMM-Newton image shows that shrapnel A consists of a bright knot and a faint trailing wake. We extracted spectra from various regions, finding a prominent Si Ly$_\\alpha$ emission line in all the spectra. All the spectra are well represented by the non-equilibrium ionization (NEI) model. The abundances are estimated to be O$\\sim$0.3, Ne$\\sim$0.9, Mg$\\sim$0.8, Si$\\sim$3, Fe$\\sim$0.8 times their solar values. The non-solar abundance ratio between O and Si indicates that shrapnel A originates from a deep layer of a progenitor star. We found that the relative abundances between heavy elements are almost uniform in shrapnel A, which suggests that the ejecta from supernova explosion are well mixed with swept-up interstellar medium.

S. Katsuda; H. Tsunemi

2006-03-17T23:59:59.000Z

129

A Miniature Maxthal Furnace for X-ray Spectroscopy and Scattering Experiments up to 1200 degrees C  

SciTech Connect

We have built a new small furnace to perform high temperature studies up to 1200 deg. C in vacuum or in oxygen atmosphere. This furnace was originally used as a catalytic reactor optimized for the in situ X-ray Absorption Spectroscopy experiments on beamline ID24. It has now been redesigned for use on the ESRF beamline ID01 for in situ Grazing Incidence Small Angle X-ray Scattering experiments. For these experiments high mechanical stability of the sample holder is necessary to keep the alignment of the sample during heating.

Gorges, Bernard; Vitoux, Hugo; Redondo, Pablo; Carbone, Gerardina [ESRF, BP220 38043 Grenoble CEDEX (France); Mocouta, Cristian [SOLEIL -BP48 91192 Gif-sur-Yvette CEDEX (France); Guilera, Gemma [ALBA CELLS 08290 Cerdanoyla Del Valles Barcelona (Spain)

2010-06-23T23:59:59.000Z

130

Using nonexponential absorption to demonstrate that anode x rays are polychromatic  

Science Journals Connector (OSTI)

Refinements are reported to the technique suggested by TELTRON for student demonstration of the polychromatic nature of the x rays generated by a conventional x?ray tube such as the TEL?X?OMETER apparatus by observing nonexponential absorption in aluminum. Excluding a linear fit on the semilog plot of transmission versus absorber thickness requires a thorough error analysis propagating the uncertainty estimates. A stored program is described which accomplishes that analysis using the minitab statistics package.

Richard D. Piccard; Sue A. Carter

1989-01-01T23:59:59.000Z

131

Novel Approaches to Soft X-ray Spectroscopy: Scanning TransmissionX-ray Microscopy and Ambient Pressure X-Ray PhotoelectronSpectroscopy  

SciTech Connect

This workshop focused on novel spectroscopies at Beamlines 11.0.2, 5.3.2 and 9.3.2 at the ALS. The workshop brought together users from a wide range of fields to highlight recent experimental and technical developments both in scanning transmission X-ray spectroscopy (STXM) and ambient pressure photoelectron spectroscopy (APPES). The morning session featured talks on experiments involving new developments at the STXM, while the afternoon session was devoted to those using APXPS. In the morning session, Tolek Tyliszczak discussed the improved detector developments at the STXM, such as an avalanche photodiode detector and fluorescence and electron detection, as well as the continued development of in situ cells for heating, gas flow, and electrochemical cells. Of these, only the avalanche photodiode in combination with a novel multichannel photon-counting system is in routine use in time-resolved studies. Bartel Van Waeyenberge (Ghent University) presented results of magnetic imaging with a time resolution of 70-100 ps combined with a lateral resolution of 20-40 nm performed with the STXM (Beamline 11.0.2). As a complement to the time-domain ''pump-and-probe'' measurements, they developed a frequency-domain ''sine-excitation'' technique in order to study specific eigenmodes of these ferromagnetic patterns with high spatial resolution. This new approach was used to study the gyrotropic vortex motions in micron-sized ferromagnetic patterns. Adam Hitchcock (McMaster University) presented the development, in collaboration with Daniel Guay (INRS, Varennes) and Sherry Zhang, of the apparatus and techniques for applying STXM to in-situ studies of electrochemistry, in particular electrochromism in polyaniline. In addition, substantial progress was reported on a joint project to develop substrates and methods for chemically selective lithography of multilayer polymer systems. Selective patterns, such as that displayed in the figure, can now be written efficiently with the bend magnet STXM on Beamline 5.3.2. Yves Acremann (SSRL) discussed time and spatially resolved X-ray magnetic circular dichroism (XMCD) experiments on spin transfer devices at the STXM (Beamline 11.0.2). These elegant experiments explore time resolved measurements of the magnetization dynamics within a 100 x 150 nm sample influenced by a spin-polarized current. This experiment shows that the magnetization in these magnetic nanostructures are not uniform, as they are influenced by the Oersted field of the charge current needed to generate the spin current. The implementation of a novel multichannel photon counting system in combination with an avalanche photon detector decreased the data-acquisition time by a factor of 10, owing to its ability to resolve the structure of multi bunch mode. Gordon E. Brown, Jr. (Stanford University and SSRL) described ''Applications of STXM to Microbial Bioweathering and Biomineralization''. In the interaction of bacteria with ferrihydrite nanoparticles, microenvironments that were very different than the bulk material were observed, showing that bulk thermodynamics may not be useful for predicting micro phases. Gordon also presented work showing that iron nanoparticles are attracted to the negatively charged bacteria and form a coating that reduces iron oxide minerals. The afternoon session started with presentations by Simon Mun and Hendrik Bluhm, who discussed the current status and the future plans for the two APPES end-stations at the ALS, which are located at Beamlines 9.3.2 and 11.0.2, respectively. In both end-stations, samples can be measured in gaseous environments at pressures of up to several Torr, which makes possible the investigation of numerous phenomena, in particular in the fields of atmospheric and environmental science as well as heterogeneous catalysis. Specific examples of the application of APPES were shown in the following presentations. John Hemminger (University of California, Irvine) reported on APPES investigations at Beamlines 9.3.2 and 11.0.2 of the interaction of alkali halide surfaces with water. The m

Bluhm, Hendrik; Gilles, Mary K.; Mun, Simon B.; Tyliszczak, Tolek

2006-02-01T23:59:59.000Z

132

Constellation-X Spectroscopy X-Ray Telescope Segmented Optic Assembly and Alignment Implementation  

E-Print Network (OSTI)

. ABSTRACT The Constellation-X mission will perform X-Ray science with improvements in energy resolutionConstellation-X Spectroscopy X-Ray Telescope Segmented Optic Assembly and Alignment Implementation and effective area over its predecessor missions. The primary instrument on each of the four Constellation

133

The puzzle of the soft X-ray excess in AGN: absorption or reflection?  

E-Print Network (OSTI)

The 2-10 keV continuum of AGN is generally well represented by a single power law. However, at smaller energies the continuum displays an excess with respect to the extrapolation of this power law, called the ''soft X-ray excess''. Until now this soft X-ray excess was attributed, either to reflection of the hard X-ray source by the accretion disk, or to the presence of an additional comptonizing medium, giving a steep spectrum. An alternative solution proposed by Gierlinski and Done (2004) is that a single power law well represents both the soft and the hard X-ray emission and the impression of the soft X-ray excess is due to absorption of a primary power law by a relativistic wind. We examine the advantages and drawbacks of reflection versus absorption models, and we conclude that the observed spectra can be well modeled, either by absorption (for a strong excess), or by reflection (for a weak excess). However the physical conditions required by the absorption models do not seem very realistic: we would pref...

Chevallier, Loïc; Dumont, A M; Czerny, B; Mouchet, M; Gonçalves, A C; Goosmann, R W

2006-01-01T23:59:59.000Z

134

The puzzle of the soft X-ray excess in AGN: absorption or reflection?  

E-Print Network (OSTI)

The 2-10 keV continuum of AGN is generally well represented by a single power law. However, at smaller energies the continuum displays an excess with respect to the extrapolation of this power law, called the ''soft X-ray excess''. Until now this soft X-ray excess was attributed, either to reflection of the hard X-ray source by the accretion disk, or to the presence of an additional comptonizing medium, giving a steep spectrum. An alternative solution proposed by Gierlinski and Done (2004) is that a single power law well represents both the soft and the hard X-ray emission and the impression of the soft X-ray excess is due to absorption of a primary power law by a relativistic wind. We examine the advantages and drawbacks of reflection versus absorption models, and we conclude that the observed spectra can be well modeled, either by absorption (for a strong excess), or by reflection (for a weak excess). However the physical conditions required by the absorption models do not seem very realistic: we would prefer an ''hybrid model''.

L. Chevallier; S. Collin; A. -M. Dumont; B. Czerny; M. Mouchet; A. C. Goncalves; R. W. Goosmann

2006-01-19T23:59:59.000Z

135

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

SciTech Connect

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.

Pascal, Tod A.; Prendergast, David, E-mail: dgprendergast@lbl.gov [The Molecular Foundry, Materials Science Division, Lawrence Berkeley National Laboratory (LBNL), Berkeley, California 94720 (United States)] [The Molecular Foundry, Materials Science Division, Lawrence Berkeley National Laboratory (LBNL), Berkeley, California 94720 (United States); Boesenberg, Ulrike; Kostecki, Robert; Richardson, Thomas J. [Environmental Energy Technologies Division, LBNL, Berkeley, California 94720 (United States)] [Environmental Energy Technologies Division, LBNL, Berkeley, California 94720 (United States); Weng, Tsu-Chien; Sokaras, Dimosthenis; Nordlund, Dennis [Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Stanford, California 94720 (United States)] [Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Stanford, California 94720 (United States); McDermott, Eamon; Moewes, Alexander [University of Saskatchewan, Department of Physics and Engineering Physics, Saskatoon, Saskatchewan S7N 5E2 (Canada)] [University of Saskatchewan, Department of Physics and Engineering Physics, Saskatoon, Saskatchewan S7N 5E2 (Canada); Cabana, Jordi [Environmental Energy Technologies Division, LBNL, Berkeley, California 94720 (United States) [Environmental Energy Technologies Division, LBNL, Berkeley, California 94720 (United States); Department of Chemistry, University of Illinois at Chicago, Chicago, Illinois 60605 (United States)

2014-01-21T23:59:59.000Z

136

Photon interference effect in x-ray absorption spectra over a wide energy range Y. Nishino and T. Ishikawa  

E-Print Network (OSTI)

. Therefore the atomic absorption coeffi- cient a is given by a a PI a ES a Incoh , 1 where a PI , a ESPhoton interference effect in x-ray absorption spectra over a wide energy range Y. Nishino and T Received 3 July 2002; published 12 September 2002 We consider fundamental structures in x-ray absorption

Korecki, Pawe³

137

Electron yield soft X-ray photoabsorption spectroscopy under normal ambient-pressure conditions  

Science Journals Connector (OSTI)

Soft X-ray photoabsorption spectroscopy under normal ambient-pressure conditions using electron yield detection was demonstrated. This technique provided unambiguous photoabsorption data for hydrated transition-metal compounds and identified the different chemical states of cobalt ions.

Tamenori, Y.

2013-03-16T23:59:59.000Z

138

X-ray imaging crystal spectroscopy for use in plasma transport research  

E-Print Network (OSTI)

This research describes advancements in the spectral analysis and error propagation techniques associated with x-ray imaging crystal spectroscopy (XICS) that have enabled this diagnostic to be used to accurately constrain ...

Bitter, M.

139

X-ray ferromagnetic resonance spectroscopy and S. Rusponi  

E-Print Network (OSTI)

-coupled multilayers,1,2,11,12 as well as current-induced magnetization excitations in spin-valve structures.13,14 Very at GHz frequencies. XMCD is defined as the dependence of the x-ray absorp- tion coefficient

Brune, Harald

140

THE STRUCTURAL CHEMISTRY OF MOLYBDENUM IN MODEL HIGH LEVEL NUCLEAR WASTE GLASSES, INVESTIGATED BY MO K-EDGE X-RAY ABSORPTION  

E-Print Network (OSTI)

THE STRUCTURAL CHEMISTRY OF MOLYBDENUM IN MODEL HIGH LEVEL NUCLEAR WASTE GLASSES, INVESTIGATED of molybdenum in model UK high level nuclear waste glasses was investigated by X-ray Absorption Spectroscopy (XAS). Molybdenum K-edge XAS data were acquired from several inactive simulant high level nuclear waste

Sheffield, University of

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


141

A microsecond time resolved x-ray absorption near edge structure synchrotron study of phase transitions in Fe undergoing ramp heating at high pressure  

SciTech Connect

We report a microsecond time-resolved x-ray absorption near edge structure study using synchrotron radiation to dynamically detect structural phase transitions in Fe undergoing rapid heating along a quasi-isochoric path. Within a few ms, we observed two structural phase transitions, which transform the ambient bcc phase of Fe into the fcc phase, and then into the liquid phase. This example illustrates the opportunities offered by energy dispersive x-ray absorption spectroscopy in the study of matter under extreme dynamic conditions. Advanced simulations are compared to these data.

Marini, C.; Mathon, O.; Pascarelli, S. [European Synchrotron Radiation Facility, 6 Rue Jules Horowitz, BP220, 38043 Grenoble Cedex (France); Occelli, F.; Torchio, R.; Recoules, V.; Loubeyre, P. [CEA, Bruyeres le Chatel, 91297 Arpajon Cedex (France)

2014-03-07T23:59:59.000Z

142

WAVELENGTH MEASUREMENTS OF K TRANSITIONS OF OXYGEN, NEON, AND MAGNESIUM WITH X-RAY ABSORPTION LINES  

SciTech Connect

Accurate atomic transition data are important in many astronomical research areas, especially for studies of line spectroscopy. Whereas transition data of He-like and H-like ions (i.e., ions in high-charge states) have been accurately calculated, the corresponding data of K transitions of neutral or low-ionized metal elements are still very uncertain. Spectroscopy of absorption lines produced in the interstellar medium (ISM) has been proven to be an effective way to measure the central wavelengths of these atomic transitions. In this work, we analyze 36 Chandra High Energy Transmission Grating observations to search for and measure the ISM absorption lines along sight lines to 11 low-mass X-ray binaries. We correct the Galactic rotation velocity to the rest frame for every observation and then use two different methods to merge all the corrected spectra to a co-added spectrum. However, the co-added spectra obtained by this method exhibit biases, toward to either observations with high counts or lines with high signal-to-noise ratios. We do a Bayesian analysis of several significantly detected lines to obtain the systematic uncertainty and the bias correction for other lines. Compared to previous studies, our results improve the wavelength accuracy by a factor of two to five and significantly reduce the systematic uncertainties and biases. Several weak transitions (e.g., 1s-2p of Mg IV and Mg V; 1s-3p of Mg III and Mg V) are also detected for the first time, albeit with low significance; future observations with improved accuracy are required to confirm these detections.

Liao Jinyuan; Zhang Shuangnan [Key Laboratory of Particle Astrophysics, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049 (China); Yao Yangsen, E-mail: zhangsn@ihep.ac.cn [Eureka Scientific, 2452 Delmer Street Suite 100, Oakland, CA 94602 (United States)

2013-09-10T23:59:59.000Z

143

Double core-hole spectroscopy of transient plasmas produced in the interaction of ultraintense x-ray pulses with neon  

E-Print Network (OSTI)

Double core-hole (DCH) spectroscopy is investigated systematically for neon atomic system in the interaction with ultraintense x-ray pulses with photon energy from 937 eV to 2000 eV. A time-dependent rate equation, implemented in the detailed level accounting approximation, is utilized to study the dynamical evolution of the level population and emission properties of the highly transient plasmas. For x-ray pulses with photon energy in the range of 937-1030 eV, where $1s\\rightarrow 2p$ resonance absorption from single core-hole (SCH) states of neon charge states exist, inner-shell resonant absorption (IRA) effects play important roles in the time evolution of population and DCH spectroscopy. Such IRA physical effects are illustrated in detail by investigating the interaction of x-ray pulses at a photon energy of 944 eV, which corresponds to the $1s\\rightarrow 2p$ resonant absorption from the SCH states ($1s2s^22p^4$, $1s2s2p^5$ and $1s2p^6$) of Ne$^{3+}$. After averaging over the space and time distribution o...

Gao, Cheng; Yuan, Jianmin

2015-01-01T23:59:59.000Z

144

The Measurement of X-Ray Absorption Coefficients by the Use of the FP-54 Pliotron  

Science Journals Connector (OSTI)

The FP-54 pliotron has been used to measure the ionization currents produced in the determination of x-ray absorption coefficients. When careful shielding was made and proper insulation provided it was found to be extremely stable in the measurement of currents of the order of magnitude 3×10-15 amperes. The x-ray absorption coefficients of copper and aluminum were determined over a range from 0.25A to 0.6A. They were found to agree quite well with those obtained by other observers and led to a value of 2.7, in the wave-length range 0.25A to 0.6A, for the constant n in the absorption equation, ??=CN4?n+??.

L. M. Heil and J. E. Edwards

1933-01-01T23:59:59.000Z

145

Low-Emittance Electron Bunches from a Laser-Plasma Accelerator Measured using Single-Shot X-Ray Spectroscopy  

E-Print Network (OSTI)

Low-Emittance Electron Bunches from a Laser-Plasma Accelerator Measured using Single-Shot X-Ray,8], x-ray [9­11], and -ray radiation [12,13]. The electron density wave gener- ated by an intense laser manuscript received 15 February 2012; published 10 August 2012) X-ray spectroscopy is used to obtain single

Geddes, Cameron Guy Robinson

146

Vibrational spectroscopy and x-ray diffraction of Cd,,OH...2 to 28 GPa at 300 K S.-H. Shim* and S. Rekhi  

E-Print Network (OSTI)

and infrared absorption spectroscopy along with x-ray diffraction for brucite-type -Cd OH 2 to 28 GPa at 300 K observed in the brucite-type hydroxides. The Raman spectra of the high-pressure phase of Cd OH 2 is similar I. INTRODUCTION High symmetry prompts considering the brucite-type hy- droxides M OH 2, M

147

X-ray absorption fine structure spectroscopic determination of plutonium speciation at the Rocky Flats environmental technology  

SciTech Connect

X-ray Absorption Fine Structure spectroscopy was used to probe the speciation of the ppm level Pu in thirteen soil and concrete samples from the Rocky Flats Environmental Technology Site in support of the site remediation effort that has been successfully completed since these measurements. In addition to X-ray Absorption Near Edge Spectra, two of the samples yielded Extended X-ray Absorption Fine Structure spectra that could be analyzed by curve-fits. Most of these spectra exhibited features consistent with PU(IV), and more specificaJly, PuO{sub 2+x}-type speciation. Two were ambiguous, possibly indicating that Pu that was originally present in a different form was transforming into PuO{sub 2+x}, and one was interpreted as demonstrating the presence of an unusual Pu(VI) compound, consistent with its source being spills from a PUREX purification line onto a concrete floor and the resultant extreme conditions. These experimental results therefore validated models that predicted that insoluble PuO{sub 2+x} would be the most stable form of Pu in equilibrium with air and water even when the source terms were most likely Pu metal with organic compounds or a Pu fire. A corollary of these models' predictions and other in situ observations is therefore that the minimal transport of Pu that occurred on the site was via the resuspension and mobilization of colloidal particles. Under these conditions, the small amounts of diffusely distributed Pu that were left on the site after its remediation pose only a negligible hazard.

Lezama-pacheco, Juan S [Los Alamos National Laboratory; Conradson, Steven D [Los Alamos National Laboratory; Clark, David L [Los Alamos National Laboratory

2008-01-01T23:59:59.000Z

148

Projections of local atomic structure revealed by wavelet analysis of x-ray absorption anisotropy P. Korecki,1,* D. V. Novikov,2 and M. Tolkiehn2  

E-Print Network (OSTI)

Projections of local atomic structure revealed by wavelet analysis of x-ray absorption anisotropy P x-ray field amplitude at the sites of absorbing atoms and effectively changes the atomic absorption in an experiment a wavelet transform approach for analysis of x-ray absorption anisotropy XAA patterns recorded

Korecki, Pawe³

149

An X-ray absorption analysis of the high-velocity system in NGC 1275  

E-Print Network (OSTI)

We present an X-ray absorption analysis of the high-velocity system (HVS) in NGC 1275 using results from a deep 200 ks Chandra observation. We are able to describe the morphology of the HVS in more detail than ever before. We present an HST image for comparison, and note close correspondence between the deepest X-ray absorption and the optical absorption. A column density map of the HVS shows an average column density NH of 1x10^21 cm^-2 with a range from ~5x10^20 to 5x10^21 cm^-2. From the NH map we calculate a total mass for the absorbing gas in the HVS of (1.32+-0.05)x10^9 solar masses at solar abundance. 75 per cent of the absorbing mass is contained in the four regions of deepest absorption. We examine temperature maps produced by spectral fitting and find no direct evidence for shocked gas in the HVS. Using deprojection methods and the depth of the observed absorption, we are able to put a lower limit on the distance of the HVS from the nucleus of 57 kpc, showing that the HVS is quite separate from the body of NGC 1275.

K. Gillmon; J. S. Sanders; A. C. Fabian

2003-10-28T23:59:59.000Z

150

Missing cosmic metals revealed by X-ray absorption towards distant sources  

E-Print Network (OSTI)

The census of heavy elements (metals) produced by all stars through cosmic times up to present-day is limited to ~50%; of these only half are still found within their parent galaxy. The majority of metals is expelled from galaxies into the circumgalactic (or even more distant, intergalactic) space by powerful galactic winds, leaving unpleasant uncertainty on the amount, thermal properties and distribution of these key chemical species. These dispersed metals unavoidably absorb soft X-ray photons from distant sources. We show that their integrated contribution can be detected in the form of increasing X-ray absorption with distance, for all kinds of high-energy cosmic sources. Based on extensive cosmological simulations, we assess that $\\sim$ 10\\% of all cosmic metals reside in the intergalactic medium. Most of the X-ray absorption arises instead from a few discrete structures along the line of sight. These extended structures, possibly pin-pointing galaxy groups, contain million degree, metal-enriched gas, 10...

Campana, S; Ferrara, A; Pallottini, A

2015-01-01T23:59:59.000Z

151

The Absorption of High Energy X-Rays in Various Materials  

Science Journals Connector (OSTI)

Effective absorption cross sections of the x-rays exciting the well-known Cu63(?,n)Cu62 reaction have been measured in a number of elements. In agreement with other workers, the experimental cross sections have been found to be lower than those predicted by theory by a fraction roughly proportional to Z2, which amounts to about 10 percent for Pb. By using the results of these measurements as a standard, the effective energies, with Pb absorbers, of the x-rays exciting the Cu12(?,n)C11, Mo92(?,n)Mo91, and Ag107(?,n)Ag106 reactions have been found to be 26.0±1.4, 17.0±1.0, and 16.1±0.9 Mev, respectively, in good agreement with resonance peak energies obtained by more elaborate methods.

H. Janzen

1952-11-01T23:59:59.000Z

152

Atmospheric Corrosion of Silver Investigated by X-ray Photoelectron Spectroscopy Dissertation  

E-Print Network (OSTI)

Atmospheric Corrosion of Silver Investigated by X-ray Photoelectron Spectroscopy Dissertation Atmospheric corrosion is a costly problem. Accelerated laboratory tests, such as the salt fog chamber, have been created to predict corrosion of materials without the need to expose them over long periods

153

The new ambient-pressure X-ray photoelectron spectroscopy instrument at MAX-lab  

Science Journals Connector (OSTI)

The new instrument for ambient-pressure X-ray photoelectron spectroscopy at the Swedish synchrotron radiation facility MAX IV Laboratory is presented. The instrument is based on the use of a retractable and exchangeable high-pressure cell, which implies that ultrahigh-vacuum conditions are retained in the analysis chamber and that dual ambient pressure and ultrahigh-vacuum use is possible.

Schnadt, J.

2012-08-07T23:59:59.000Z

154

Passive Spectroscopy Bolometers, Grating- And X-Ray Imaging Crystal Spectrometers  

SciTech Connect

This tutorial gives a brief introduction into passive spectroscopy and describes the working principles of bolometers, a high-resolution grating spectrometer, and a novel X-ray imaging crystal spectrometer, which is of particular interest for profile measurements of the ion temperature and plasma rotation velocity on ITER and future burning plasma experiments.

Bitter, M; Hill, K W; Scott, S; Paul, S; Ince-Cushmann, A; Reinke, M; Rice, J; Beiersdorfer, P; Gu, M F; Lee, S G; Broennimann, C; Eikenberry, E F

2007-11-07T23:59:59.000Z

155

Stereochemistry Determination by Powder X-ray Diffraction Analysis and NMR Spectroscopy Residual Dipolar Couplings  

SciTech Connect

A matter of technique: For a new steroidal lactol, jaborosalactol 24 (1), isolated from Jaborosa parviflora, NMR spectroscopy residual dipolar couplings and powder X-ray diffraction analysis independently gave the same stereochemistry at C23-C26. Conventional NMR spectroscopic techniques, such as NOE and {sup 3}J coupling-constant analysis failed to unambiguously determine this stereochemistry.

Garcia, M.; Pagola, S; Navarro-Vasquez, A; Phillips, D; Gayathri, C; Krakauer, H; Stephens, P; Nicotra, V; Gil, R

2009-01-01T23:59:59.000Z

156

HIV-1 Tat membrane interactions probed using X-ray and neutron scattering, CD spectroscopy and MD simulations  

E-Print Network (OSTI)

HIV-1 Tat membrane interactions probed using X-ray and neutron scattering, CD spectroscopy and MD translocation, were provided by wide-angle X-ray scattering (WAXS) and neutron scattering. CD spectroscopy for Neutron Research, 100 Bureau Drive, Stop 6102, Gaithersburg, MD 20899, United States d CHESS, Cornell

Nagle, John F.

157

Elimination of self-absorption in fluorescence hard-x-ray absorption spectra P. Pfalzer, J.-P. Urbach, M. Klemm, and S. Horn  

E-Print Network (OSTI)

Elimination of self-absorption in fluorescence hard-x-ray absorption spectra P. Pfalzer, J-ray absorption spectra in situations where samples cannot be made in the required configuration. However, self-absorption-ray absorption coefficients. This procedure is used to obtain the vanadium K-edge spectrum of single crystal V2O3

Frenkel, Anatoly

158

Transition-metal (Au, Pt, Ir, Re) bonding to Al,Si,Ge: X-ray-absorption studies  

Science Journals Connector (OSTI)

We report transition-metal (T) L2 and L3 near-edge x-ray-absorption spectroscopy measurements on more than a score of T-X compounds with T=Au, Pt, Ir, and Re and X=Al, Si, and Ge. We correlate the strength of the (2p?5d)-related ‘‘white line’’ feature at these edges to the degree of chemical-bonding-induced 5d-orbital charge transfer in these materials. Similar bonding trends are shown to be present in 1:2:2 compounds involving these T and X elements. Finally, the bonding-induced charge-transfer effects in such T-X compounds are discussed along with the Pauling electronegativity scale. [L. Pauling, The Nature of the Chemical Bond (Cornell University Press, New York, 1960), p. 93.

Y. Jeon, Boyun Qi, F. Lu, and M. Croft

1989-07-15T23:59:59.000Z

159

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

SciTech Connect

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

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

2011-05-15T23:59:59.000Z

160

Vibronic theory for the x-ray absorption spectrum of CF4 molecules  

Science Journals Connector (OSTI)

The C 1s x-ray absorption spectrum of CF4 molecules is theoretically investigated by calculating the line shape quantum mechanically based upon a vibronic model. It is found that the main peak with a broad width is attributed to the transition of the C 1s core electron to the antibonding valence orbitals which are coupled with the C—F bond-stretching modes through the Jahn-Teller and the quasi-Jahn-Teller interactions. It is also clarified that the sharp asymmetric absorption line at the higher-energy side of the main band comes from the transition to the Rydberg states, where the interference effect between the Rydberg states and the vibronic state of the antibonding molecular orbitals leads to the asymmetric structure.

Shin-ichi Itoh; Satoshi Tanaka; Yosuke Kayanuma

1999-12-01T23:59:59.000Z

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


161

Characterization of atmospheric aerosols using Synchroton radiation total reflection X-ray fluorescence and Fe K-edge total reflection X-ray fluorescence-X-ray absorption near-edge structure  

Science Journals Connector (OSTI)

In this study a new procedure using Synchrotron total reflection X-ray fluorescence (SR-TXRF) to characterize elemental amounts in atmospheric aerosols down to particle sizes of 0.015 um is presented. The procedure was thoroughly evaluated regarding bounce off effects and blank values. Additionally the potential of total reflection X-ray fluorescence–X-ray absorption near edge structure (SR-TXRF-XANES) for speciation of FeII/III down to amounts of 34 pg in aerosols which were collected for 1 h is shown. The aerosols were collected in the city of Hamburg with a low pressure Berner impactor on Si carriers covered with silicone over time periods of 60 and 20 min each. The particles were collected in four and ten size fractions of 10.0–8.0 ?m, 8.0–2.0 ?m, 2.0–0.13 ?m 0.13–0.015 ?m (aerodynamic particle size) and 15–30 nm, 30–60 nm, 60–130 nm, 130–250 nm, 250–500 nm, 0.5–1 ?m, 1–2 ?m, 2–4 ?m, 4–8 ?m, 8–16 ?m. Prior to the sampling “bounce off” effects on Silicone and Vaseline coated Si carriers were studied with total reflection X-ray fluorescence. According to the results silicone coated carriers were chosen for the analysis. Additionally, blank levels originating from the sampling device and the calibration procedure were studied. Blank levels of Fe corresponded to 1–10% of Fe in the aerosol samples. Blank levels stemming from the internal standard were found to be negligible. The results from the Synchroton radiation total reflection X-ray fluorescence analysis of the aerosols showed that 20 min of sampling time gave still enough sample material for elemental determination of most elements. For the determination of the oxidation state of Fe in the aerosols different Fe salts were prepared as a reference from suspensions in isopropanol. The results from the Fe K-edge Synchroton radiation total reflection X-ray fluorescence-X-ray absorption near-edge structure analysis of the aerosol samples showed that mainly Fe(III) was present in all particle size fractions.

U.E.A. Fittschen; F. Meirer; C. Streli; P. Wobrauschek; J. Thiele; G. Falkenberg; G. Pepponi

2008-01-01T23:59:59.000Z

162

Characterization of Gas Shales by X-ray Raman Spectroscopy | Stanford  

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

Characterization of Gas Shales by X-ray Raman Spectroscopy Characterization of Gas Shales by X-ray Raman Spectroscopy Thursday, February 23, 2012 - 10:30am SSRL Third Floor Conference Room 137-322 Drew Pomerantz, Schlumberger Unconventional hydrocarbon resources such as gas shale and oil-bearing shale have emerged recently as economically viable sources of energy, dramatically altering America's energy landscape. Despite their importance, the basic chemistry and physics of shales are not understood as well as conventional reservoirs. In particular, shales are unique in that they contain kerogen, a complex organic solid that controls factors such as the amount of hydrocarbon that can be produced from the reservoir and the rate at which the hydrocarbon is produced. The industry's current understanding of the chemical composition of kerogen is limited, preventing detailed

163

Characterization of Gas Shales by X-ray Raman Spectroscopy | Stanford  

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

Characterization of Gas Shales by X-ray Raman Spectroscopy Characterization of Gas Shales by X-ray Raman Spectroscopy Monday, May 14, 2012 - 3:30pm SSRL Conference Room 137-322 Drew Pomerantz, Schlumberger Unconventional hydrocarbon resources such as gas shale and oil-bearing shale have emerged recently as economically viable sources of energy, dramatically altering America's energy landscape. Despite their importance, the basic chemistry and physics of shales are not understood as well as conventional reservoirs. In particular, shales are unique in that they contain kerogen, a complex organic solid that controls factors such as the amount of hydrocarbon that can be produced from the reservoir and the rate at which the hydrocarbon is produced. The industry's current understanding of the chemical composition of kerogen is limited, preventing detailed

164

X-Ray Spectroscopy of the Photosynthetic Oxygen-Evolving Complex  

SciTech Connect

Water oxidation to dioxygen in photosynthesis is catalyzed by a Mn{sub 4}Ca cluster with O bridging in Photosystem II (PS II) of plants, algae and cyanobacteria. A variety of spectroscopic methods have been applied to analyzing the participation of the complex. X-ray spectroscopy is particularly useful because it is element-specific, and because it can reveal important structural features of the complex with high accuracy and identify the participation of Mn in the redox chemistry. Following a brief history of the application of X-ray spectroscopy to PS II, an overview of newer results will be presented and a description of the present state of our knowledge based on this approach.

Sauer, K.; Yano, J.; Yachandra, V.K.

2009-05-27T23:59:59.000Z

165

X-ray Photoelectron Spectroscopy Studies of Oxidized and Reduced CeO?(111) Surfaces  

SciTech Connect

We have studied the electronic structure of oxidized and reduced CeO? (111) surfaces using X-ray photoelectron spectroscopy (XPS). The 50 nm thick Co?(111) film was grown on a YSZ(111) substrate using oxygen plasma assisted molecular beam epitaxy (OPA-MBE). This film has been characterized using in-situ RHEED (reflection high energy electron diffraction) and ex-situ XRD (X-ray diffraction), HRTEM (high resolution transmission electron microscopy) and RBS (Rutherford backscattering spectroscopy). The lattice mismatch between CeO?(111) and YSZ(111) is less than 5% and yields a flat surface that is comprised of an equivalent number of Ce?? and O?? ions. Oxidation with O? at 773 K under UHV conditions was sufficient to fully oxidize the CeO?(111). Surface reduction was carried out by annealing in UHV at 973 K.

Engelhard, Mark H.; Azad, Samina; Peden, Charles HF; Thevuthasan, Suntharampillai

2004-12-01T23:59:59.000Z

166

X-ray four-wave mixing in molecules Satoshi Tanaka  

E-Print Network (OSTI)

X-ray four-wave mixing in molecules Satoshi Tanaka Department of Chemistry, University of Rochester radiation intense light sources have opened up a new era in soft x-ray spectroscopy. The dramatic improvements of spectral resolution in x-ray absorption1,2 and x-ray photoemission spectra3 have revealed

Mukamel, Shaul

167

Many-body Green's function approach to attosecond nonlinear x-ray spectroscopy Upendra Harbola1 and Shaul Mukamel2  

E-Print Network (OSTI)

Many-body Green's function approach to attosecond nonlinear x-ray spectroscopy Upendra Harbola1 in terms of one- and two-particle Green's functions which can be obtained from the solution of Hedin stimulated x-ray Raman signals CXRS . It was shown that CXRS can be expressed in terms of one- particle Green

Mukamel, Shaul

168

Methods development for diffraction and spectroscopy studies of metalloenzymes at X-ray free-electron lasers  

Science Journals Connector (OSTI)

...on electrofocusing, an energy dispersive von Hamos X-ray...spectroscopy data collected by us at the Linac Coherent...deposition of radiation energy by the X-ray pulse was...we review the current status of methods developed in...packages developed by us to process both spectroscopic...

2014-01-01T23:59:59.000Z

169

Transient Absorption Spectroscopy with Isolated Attosecond Pulses  

E-Print Network (OSTI)

viii Attosecond transient absorption instrument. . . . . .5.2.2 AbsorptionTransient absorption spectroscopy . . . . . . . . . . . .

Bell, Marie Justine

2013-01-01T23:59:59.000Z

170

Probing the hydrogen-bond network of water via time-resolved soft x-ray spectroscopy  

SciTech Connect

We report time-resolved studies of hydrogen bonding in liquid H2O, in response to direct excitation of the O-H stretch mode at 3 mu m, probed via soft x-ray absorption spectroscopy at the oxygen K-edge. This approach employs a newly developed nanofluidic cell for transient soft x-ray spectroscopy in liquid phase. Distinct changes in the near-edge spectral region (XANES) are observed, and are indicative of a transient temperature rise of 10K following transient laser excitation and rapid thermalization of vibrational energy. The rapid heating occurs at constant volume and the associated increase in internal pressure, estimated to be 8MPa, is manifest by distinct spectral changes that differ from those induced by temperature alone. We conclude that the near-edge spectral shape of the oxygen K-edge is a sensitive probe of internal pressure, opening new possibilities for testing the validity of water models and providing new insight into the nature of hydrogen bonding in water.

Huse, Nils; Wen, Haidan; Nordlund, Dennis; Szilagyi, Erzsi; Daranciang, Dan; Miller, Timothy A.; Nilsson, Anders; Schoenlein, Robert W.; Lindenberg, Aaron M.

2009-04-24T23:59:59.000Z

171

X-ray fluorescence spectroscopy from ions at charged vapor/water interfaces  

E-Print Network (OSTI)

X-ray fluorescence spectra from monovalent ions (Cs+) that accumulate from dilute solutions to form an ion-rich layer near a charged Langmuir monolayer are presented. For the salt solution without the monolayer, the fluorescence signals below the critical angle are significantly lower than the detection sensitivity and only above the critical angle signals from the bulk are observed. In the presence of a monolayer that provides surface charges, strong fluorescence signals below the critical angle are observed. Ion density accumulated at the interface are determined from the fluorescence. The fluorescent spectra collected as a function of incident x-ray energy near the LIII edge yield the extended absorption spectra from the ions, and are compared to recent independent results. The fluorescence data from divalent Ba2+ with and without monolayer are also presented.

Wei Bu; David Vaknin

2009-05-04T23:59:59.000Z

172

Polarization Dependent High Energy Resolution X-ray Absorption Study of Dicesium Uranyl Tetrachloride  

Science Journals Connector (OSTI)

Tonya Vitova *†, Jennifer C. Green ‡, Robert G. Denning ‡, Matthias Löble †, Kristina Kvashnina §, Joshua J. Kas ?, Kevin Jorissen ?, John J. Rehr ?, Thomas Malcherek ?, and Melissa A. Denecke † ... This study confirms theoretically predicted electronic transitions to U 6dxy (6d?) orbital and measures relative energies of U 5f?, 5f?, 5f?, and 5f? orbitals of oriented uranyl (UVIO22+) in the same spectrum with remarkable energy resolution. ... We have obtained angle-resolved electronic structure information for oriented Cs2UO2Cl4 crystal, specifically relative energies of 5f and 6d valence orbitals probed with extraordinary energy resolution by polarization dependent high energy resolution X-ray absorption near edge structure (PD-HR-XANES) and compare these with predictions from quantum chemical Amsterdam density functional theory (ADF) and ab initio real space multiple-scattering Green’s function based FEFF codes. ...

Tonya Vitova; Jennifer C. Green; Robert G. Denning; Matthias Löble; Kristina Kvashnina; Joshua J. Kas; Kevin Jorissen; John J. Rehr; Thomas Malcherek; Melissa A. Denecke

2014-12-08T23:59:59.000Z

173

In situ x-ray photoelectron spectroscopy for electrochemical reactions in ordinary solvents  

SciTech Connect

In situ electrochemical X-ray photoelectron spectroscopy (XPS) apparatus, which allows XPS at solid/liquid interfaces under potential control, was constructed utilizing a microcell with an ultra-thin Si membrane, which separates vacuum and a solution. Hard X-rays from a synchrotron source penetrate into the Si membrane surface exposed to the solution. Electrons emitted at the Si/solution interface can pass through the membrane and be analyzed by an analyzer placed in vacuum. Its operation was demonstrated for potential-induced Si oxide growth in water. Effect of potential and time on the thickness of Si and Si oxide layers was quantitatively determined at sub-nanometer resolution.

Masuda, Takuya [Global Research Center for Environment and Energy Based on Nanomaterials Science (GREEN), National Institute for Materials Science (NIMS), Tsukuba 305-0044 (Japan) [Global Research Center for Environment and Energy Based on Nanomaterials Science (GREEN), National Institute for Materials Science (NIMS), Tsukuba 305-0044 (Japan); PRESTO, Japan Science and Technology Agency (JST), 4-1-8 Honcho, Kawaguchi, Saitama 333-0012 (Japan); Yoshikawa, Hideki; Kobata, Masaaki; Kobayashi, Keisuke [Synchrotron X-ray Station at SPring-8, National Institute for Materials Science (NIMS), Sayo, Hyogo 679-5148 (Japan)] [Synchrotron X-ray Station at SPring-8, National Institute for Materials Science (NIMS), Sayo, Hyogo 679-5148 (Japan); Noguchi, Hidenori [Global Research Center for Environment and Energy Based on Nanomaterials Science (GREEN), National Institute for Materials Science (NIMS), Tsukuba 305-0044 (Japan) [Global Research Center for Environment and Energy Based on Nanomaterials Science (GREEN), National Institute for Materials Science (NIMS), Tsukuba 305-0044 (Japan); PRESTO, Japan Science and Technology Agency (JST), 4-1-8 Honcho, Kawaguchi, Saitama 333-0012 (Japan); Graduate School of Chemical Sciences and Engineering, Hokkaido University, Sapporo, Hokkaido 060-0810 (Japan); International Center for Materials Nanoarchitectonics (WPI-MANA), National Institute for Materials Science (NIMS), Tsukuba, Ibaraki 305-0044 (Japan); Kawasaki, Tadahiro [Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa, Nagoya 464-8603 (Japan)] [Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa, Nagoya 464-8603 (Japan); Uosaki, Kohei [Global Research Center for Environment and Energy Based on Nanomaterials Science (GREEN), National Institute for Materials Science (NIMS), Tsukuba 305-0044 (Japan) [Global Research Center for Environment and Energy Based on Nanomaterials Science (GREEN), National Institute for Materials Science (NIMS), Tsukuba 305-0044 (Japan); Graduate School of Chemical Sciences and Engineering, Hokkaido University, Sapporo, Hokkaido 060-0810 (Japan); International Center for Materials Nanoarchitectonics (WPI-MANA), National Institute for Materials Science (NIMS), Tsukuba, Ibaraki 305-0044 (Japan)

2013-09-09T23:59:59.000Z

174

The role of absorption and reflection in the soft X-ray excess of Active Galactic Nuclei : 1. Preliminary results  

E-Print Network (OSTI)

The 2-10 keV continuum of AGN is well represented by a single power law, generally attributed to a hot comptonizing medium, such as a corona above the accretion disk. At smaller energies the continuum displays an excess with respect to the extrapolation of this power law, called the ``soft X-ray excess". Until now it was attributed, either to reflection of the hard X-ray source by the accretion disk, or to the presence of an additional comptonizing medium. An alternative solution proposed by Gierli\\'nski & Done (2004) is that a single power law represents correctly both the soft and the hard X-ray emission, and the soft X-ray excess is an artefact due to the absorption of the primary power law by a relativistic wind. We examine the advantages and drawbacks of the reflection versus absorption models. We argue that in the absorption hypothesis, the absorbing medium should be in total pressure equilibrium, to constrain the spectral distribution which otherwise would be too strongly variable in time and from one object to the other, as compared to observations. We conclude that some X-ray spectra, in particular those with strong soft X-ray excesses, can be modelled by absorption in the 0.3-10 keV range. However, due to the lack of a complete grid of models and good data extending above 10 keV, we are not able to conclude presently that all objects can be accommodated with such models. These absorption models imply either strong relativistic outflowing winds with mass rates of the order of the Eddington value (or even larger), or quasi-spherical inhomogeneous accretion flows. Only weak excesses can be modelled by reflection, unless the primary continuum is not directly seen. Finally, a reflection model absorbed by a modest relativistic wind could be the best solution to the problem.

Loïc Chevallier; Suzy Collin; Anne-Marie Dumont; Bozena Czerny; Martine Mouchet; Anabela C. Gonçalves; René Goosmann

2005-11-01T23:59:59.000Z

175

HELIUM IN NATAL H II REGIONS: THE ORIGIN OF THE X-RAY ABSORPTION IN GAMMA-RAY BURST AFTERGLOWS  

SciTech Connect

Soft X-ray absorption in excess of Galactic is observed in the afterglows of most gamma-ray bursts (GRBs), but the correct solution to its origin has not been arrived at after more than a decade of work, preventing its use as a powerful diagnostic tool. We resolve this long-standing problem and find that absorption by He in the GRB's host H II region is responsible for most of the absorption. We show that the X-ray absorbing column density (N{sub H{sub X}}) is correlated with both the neutral gas column density and with the optical afterglow's dust extinction (A{sub V} ). This correlation explains the connection between dark bursts and bursts with high N{sub H{sub X}} values. From these correlations, we exclude an origin of the X-ray absorption which is not related to the host galaxy, i.e., the intergalactic medium or intervening absorbers are not responsible. We find that the correlation with the dust column has a strong redshift evolution, whereas the correlation with the neutral gas does not. From this, we conclude that the column density of the X-ray absorption is correlated with the total gas column density in the host galaxy rather than the metal column density, in spite of the fact that X-ray absorption is typically dominated by metals. The strong redshift evolution of N{sub H{sub X}}/A{sub V} is thus a reflection of the cosmic metallicity evolution of star-forming galaxies and we find it to be consistent with measurements of the redshift evolution of metallicities for GRB host galaxies. We conclude that the absorption of X-rays in GRB afterglows is caused by He in the H II region hosting the GRB. While dust is destroyed and metals are stripped of all of their electrons by the GRB to great distances, the abundance of He saturates the He-ionizing UV continuum much closer to the GRB, allowing it to remain in the neutral or singly-ionized state. Helium X-ray absorption explains the correlation with total gas, the lack of strong evolution with redshift, as well as the absence of dust, metal or hydrogen absorption features in the optical-UV spectra.

Watson, Darach; Andersen, Anja C.; Fynbo, Johan P. U.; Hjorth, Jens; Kruehler, Thomas; Laursen, Peter; Leloudas, Giorgos; Malesani, Daniele [Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen, Juliane Maries Vej 30, DK-2100 Copenhagen O (Denmark); Zafar, Tayyaba [Laboratoire d'Astrophysique de Marseille - LAM, Universite Aix-Marseille and CNRS, UMR 7326, 38 rue F. Joliot-Curie, F-13388, Marseille Cedex 13 (France); Gorosabel, Javier [Instituto de Astrofisica de Andalucia (IAA-CSIC), Glorieta de la Astronomia s/n, E-18008, Granada (Spain); Jakobsson, Pall, E-mail: darach@dark-cosmology.dk [Centre for Astrophysics and Cosmology, Science Institute, University of Iceland, Dunhagi 5, 107 Reykjavik (Iceland)

2013-05-01T23:59:59.000Z

176

Slow dynamics of nanocomposite polymer aerogels as revealed by X-ray photocorrelation spectroscopy (XPCS)  

SciTech Connect

We report on a novel slow dynamics of polymer xerogels, aerogels, and nanocomposite aerogels with iron oxide nanoparticles, as revealed by X-ray photon correlation spectroscopy. The polymer aerogel and its nanocomposite aerogels, which are porous in nature, exhibit hyper-diffusive dynamics at room temperature. In contrast, non-porous polymer xerogels exhibit an absence of this peculiar dynamics. This slow dynamical process has been assigned to a relaxation of the characteristic porous structure of these materials and not to the presence of nanoparticles.

Hernández, Rebeca, E-mail: rhernandez@ictp.csic.es, E-mail: aurora.nogales@csic.es; Mijangos, Carmen [Instituto de Ciencia y Tecnología de Polímeros, ICTP-CSIC, Juan de la Cierva, 3, 28006 Madrid (Spain)] [Instituto de Ciencia y Tecnología de Polímeros, ICTP-CSIC, Juan de la Cierva, 3, 28006 Madrid (Spain); Nogales, Aurora, E-mail: rhernandez@ictp.csic.es, E-mail: aurora.nogales@csic.es; Ezquerra, Tiberio A. [Instituto de Estructura de la Materia, IEM-CSIC, Serrano 121, 28006 Madrid (Spain)] [Instituto de Estructura de la Materia, IEM-CSIC, Serrano 121, 28006 Madrid (Spain); Sprung, Michael [Petra III at DESY, Notkestr. 85, 22607 Hamburg (Germany)] [Petra III at DESY, Notkestr. 85, 22607 Hamburg (Germany)

2014-01-14T23:59:59.000Z

177

Magnetic dichroism in valence-band x-ray photoemission spectroscopy  

Science Journals Connector (OSTI)

A fully relativistic description of spin-resolved valence-band x-ray photoemission spectroscopy (VB-XPS) of magnetic solids is presented that is based on multiple scattering theory. This approach allows us to investigate possible magnetic dichroism in VB-XPS. As is demonstrated by results for CoxPt1-x, application to disordered alloys is straightforward within the framework of the coherent potential approximation alloy theory. The spin-integrated spectra for unpolarized radiation were found to be in very satisfying agreement with corresponding experimental data. For the spin-resolved spectra a pronounced magnetic circular dichroism is predicted that should be easily observed.

H. Ebert and J. Schwitalla

1997-02-01T23:59:59.000Z

178

Oxidation of stepped Pt(111) studied by x-ray photoelectron spectroscopy and density functional theory  

SciTech Connect

In this comparative density functional theory and x-ray photoelectron spectroscopy study on the interaction of oxygen with stepped Pt(111) surfaces, we show that both the initial adsorption and oxidation occur at the steps rather than terraces. An equivalent behavior was observed for the oxide formation at higher chemical potentials, where, after the formation of a one-dimensional PtO{sub 2}-type oxide at the steps, similar oxide chains form on the (111) terraces, indicating the initial stages of bulk oxide formation.

Bandlow, Jochen; Kaghazchi, Payam; Jacob, Timo [Institut fuer Elektrochemie, Universitaet Ulm, Albert-Einstein-Allee 47, D-89069 Ulm (Germany); Papp, C.; Traenkenschuh, B.; Streber, R.; Lorenz, M. P. A.; Fuhrmann, T.; Steinrueck, H.-P. [Lehrstuhl fuer Physikalische Chemie II, Universitaet Erlangen-Nuernberg, Egerlandstr. 3, D-91058 Erlangen (Germany); Denecke, R. [Wilhelm-Ostwald-Institut fuer Physikalische und Theoretische Chemie, Universitaet Leipzig, Linnestr. 2, D-04103 Leipzig (Germany)

2011-05-01T23:59:59.000Z

179

Long-term X-ray stability and UV variability of the ionized absorption in NGC 3783  

E-Print Network (OSTI)

We present the results of recent Chandra High-Energy Transmission Grating Spectrometer and Hubble Space Telescope Cosmic Origins Spectrograph observations of the nearby Seyfert 1 galaxy NGC 3783 which shows a strong, non-varying X-ray warm absorber and physically related and kinematically varying UV absorption. We compare our new observations to high-resolution, high signal-to-noise archival data from 2001, allowing a unique investigation into the long-term variations of the absorption over a 12 yr period. We find no statistically significant changes in the physical properties of the X-ray absorber, but there is a significant drop of ~40% in the UV and X-ray flux, and a significant flattening of the underlying X-ray power-law slope. Large kinematic changes are seen in the UV absorbers, possibly due to radial deceleration of the material. Similar behavior is not observed in the X-ray data, likely due to its lower velocity resolution, which shows an outflow velocity of v ~ -655 km/s in both epochs. The narrow i...

Scott, A E; Behar, E; Crenshaw, D M; Gabel, J R; Gibson, R R; Kaspi, S; Kraemer, S B; Turner, T J

2014-01-01T23:59:59.000Z

180

Arsenic Speciation in Solids Using X-ray Absorption Spectroscopy  

Science Journals Connector (OSTI)

...drugs voluntarily withdrawn from the US market by its manufacturer in 2013 (only nitarsone...used for industrial heat production or in diesel engines (Huffman et al. 2000). XANES...oxidation states. The authors postulated diesel exhaust, residential central heating...

Andrea L. Foster; Christopher S. Kim

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


181

Arsenic Speciation in Solids Using X-ray Absorption Spectroscopy  

Science Journals Connector (OSTI)

...strongly-bound polymerized species whose fundamental repeating unit contains AsO4 bound...industrial heat production or in diesel engines (Huffman et al. 2000). XANES...states. The authors postulated diesel exhaust, residential central heating...

Andrea L. Foster; Christopher S. Kim

182

X-ray Absorption Spectroscopy of Biologically Relevant Systems  

E-Print Network (OSTI)

sodium acetate, and lithium acetate revealing distinctpotassium, and lithium with acetate and formate anions informate and acetate solutions containing lithium, sodium,

Uejio, Janel Sunayo

2010-01-01T23:59:59.000Z

183

X-ray Absorption Spectroscopy of Biologically Relevant Systems  

E-Print Network (OSTI)

22 The electronic structure calculation is performed usingplane-wave electronic structure calculations required tousing an SCF calculation to model the electronic structure

Uejio, Janel Sunayo

2010-01-01T23:59:59.000Z

184

XPS: A multi-channel preamplifier shaper IC for X-ray spectroscopy  

SciTech Connect

An integrated circuit featuring 48 channels of charge-sensitive preamplifiers followed by variable-gain pulse shaping amplifiers is being developed as part of an x-ray spectrometer with a highly segmented detector to handle high fluxes in synchrotron experiments. Such detector systems can provide excellent energy resolution combined with one-dimensional spatial information. The IC combines many basic spectroscopy amplifier functions with a low-noise preamplifier section to produce a unique circuit capable of driving conventional ADC modules directly. An important feature of the design is the novel CR-RC{sup 2} pulse shaper. In this section, high-linearity transconductor circuits are required in order to provide a broad range of continuously variable peaking times while still maintaining the linearity and noise performance necessary for x-ray spectroscopy. Reported here are first measurements made on the performance of a 16-channel prototype integrated circuit. At present, the preamplifier-shaper circuit achieves an equivalent input noise of 26 electrons rms at 2 {micro}s peaking time with a 0.2 pF external capacitor, which is similar to the capacitance of a single detector element. The design was fabricated in standard 1.2 {micro}m CMOS technology.

Krieger, B.; Kipnis, I.; Ludewigt, B.A.

1997-11-01T23:59:59.000Z

185

High resolution X-ray spectroscopy with XMM-Newton and Chandra, MSSL, 24 -25 October 2002 1 HIGH RESOLUTION X-RAY SPECTROSCOPY WITH  

E-Print Network (OSTI)

of the system, the density and absorp- tion of the wind, eclipses, or variability due to the inclination that the soft X-rays ( #24; wind produced by the common mechanism that are much narrower ( #24; wind

Guedel, Manuel

186

CHANDRA PHASE-RESOLVED X-RAY SPECTROSCOPY OF THE CRAB PULSAR  

SciTech Connect

We present a new study of the X-ray spectral properties of the Crab Pulsar. The superb angular resolution of the Chandra X-Ray Observatory enables distinguishing the pulsar from the surrounding nebulosity. Analysis of the spectrum as a function of pulse phase allows the least-biased measure of interstellar X-ray extinction due primarily to photoelectric absorption and secondarily to scattering by dust grains in the direction of the Crab Nebula. We modify previous findings that the line of sight to the Crab is underabundant in oxygen and provide measurements with improved accuracy and less bias. Using the abundances and cross sections from Wilms et al. we find [O/H] = (5.28 {+-} 0.28) Multiplication-Sign 10{sup -4} (4.9 Multiplication-Sign 10{sup -4} is solar abundance). We also measure for the first time the impact of scattering of flux out of the image by interstellar grains. We find {tau}{sub scat} = 0.147 {+-} 0.043. Analysis of the spectrum as a function of pulse phase also measures the X-ray spectral index even at pulse minimum-albeit with increasing statistical uncertainty. The spectral variations are, by and large, consistent with a sinusoidal variation. The only significant variation from the sinusoid occurs over the same phase range as some rather abrupt behavior in the optical polarization magnitude and position angle. We also compare these spectral variations to those observed in gamma-rays and conclude that our measurements are both a challenge and a guide to future modeling and will thus eventually help us understand pair cascade processes in pulsar magnetospheres. The data are also used to set new, and less biased, upper limits to the surface temperature of the neutron star for different models of the neutron star atmosphere. We discuss how such data are best connected to theoretical models of neutron star cooling and neutron star interiors. The data restrict the neutrino emission rate in the pulsar core and the amount of light elements in the heat-blanketing envelope. The observations allow the pulsar, irrespective of the composition of its envelope, to have a neutrino emission rate higher than {approx}0.2 of the standard rate of a non-superfluid star cooling via the modified Urca process. The observations also allow the rate to be lower but now with a limited amount of accreted matter in the envelope.

Weisskopf, Martin C.; Tennant, Allyn F.; O'Dell, Stephen L.; Elsner, Ronald F. [Space Sciences Department, NASA Marshall Space Flight Center, VP62, Huntsville, AL 35812 (United States); Yakovlev, Dmitry G. [Ioffe Physical Technical Institute, Politechnischeskaya 26, 194021 St. Petersburg (Russian Federation); Harding, Alice [NASA Goddard Space Flight Center, 8800, College Park, MD 20771 (United States); Zavlin, Vyacheslav E. [NASA Marshall Space Flight Center, Universities Space Research Association, VP62, Huntsville, AL 35812 (United States); Becker, Werner [Max-Planck-Institut fuer Extraterrestrische Physik, 85740 Garching bei Muenchen (Germany)

2011-12-20T23:59:59.000Z

187

Masked-backlighter technique used to simultaneously image x-ray absorption and x-ray emission from an inertial confinement fusion plasma  

SciTech Connect

A method to simultaneously image both the absorption and the self-emission of an imploding inertial confinement fusion plasma has been demonstrated on the OMEGA Laser System. The technique involves the use of a high-Z backlighter, half of which is covered with a low-Z material, and a high-speed x-ray framing camera aligned to capture images backlit by this masked backlighter. Two strips of the four-strip framing camera record images backlit by the high-Z portion of the backlighter, while the other two strips record images aligned with the low-Z portion of the backlighter. The emission from the low-Z material is effectively eliminated by a high-Z filter positioned in front of the framing camera, limiting the detected backlighter emission to that of the principal emission line of the high-Z material. As a result, half of the images are of self-emission from the plasma and the other half are of self-emission plus the backlighter. The advantage of this technique is that the self-emission simultaneous with backlighter absorption is independently measured from a nearby direction. The absorption occurs only in the high-Z backlit frames and is either spatially separated from the emission or the self-emission is suppressed by filtering, or by using a backlighter much brighter than the self-emission, or by subtraction. The masked-backlighter technique has been used on the OMEGA Laser System to simultaneously measure the emission profiles and the absorption profiles of polar-driven implosions.

Marshall, F. J., E-mail: fredm@lle.rochester.edu; Radha, P. B. [Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623 (United States)

2014-11-15T23:59:59.000Z

188

Arraying compact pixels of transition-edge microcalorimeters for imaging x-ray spectroscopy  

Science Journals Connector (OSTI)

We are developing superconducting transition-edge sensor (TES) microcalorimeters for astronomical x-ray spectroscopy. We have obtained very high energy resolution (2.4 eV at 1.5 keV and 3.7 eV at 3.3 keV) in large isolated TES pixels using Mo/Au proximity-effect bilayers on silicon-nitride membranes several mm wide. In order to be truly suitable for use behind an x-ray telescope however such devices need to be arrayed with a pixel size and focal-plane coverage matched to the telescope focal length and spatial resolution. For the Constellation-X mission this requires fitting the TES its thermal link and contact wiring into a 0.25 mm square a far more compact geometry than has previously been investigated. We have demonstrated that the weak thermal link can be restricted to a narrow (?10 micron) perimeter of membrane around the TES and still provide a thermal conductance in the acceptable range. Varying the size and placement of slits in that nitride perimeter we can tune that value.

C. K. Stahle; M. A. Lindeman; E. Figueroa-Feliciano; M. J. Li; N. Tralshawala; F. M. Finkbeiner; R. P. Brekosky; J. A. Chervenak

2002-01-01T23:59:59.000Z

189

X-ray imaging crystal spectroscopy for use in plasma transport research  

SciTech Connect

This research describes advancements in the spectral analysis and error propagation techniques associated with x-ray imaging crystal spectroscopy (XICS) that have enabled this diagnostic to be used to accurately constrain particle, momentum, and heat transport studies in a tokamak for the first time. Doppler tomography techniques have been extended to include propagation of statistical uncertainty due to photon noise, the effect of non-uniform instrumental broadening as well as flux surface variations in impurity density. These methods have been deployed as a suite of modeling and analysis tools, written in interactive data language (IDL) and designed for general use on tokamaks. Its application to the Alcator C-Mod XICS is discussed, along with novel spectral and spatial calibration techniques. Example ion temperature and radial electric field profiles from recent I-mode plasmas are shown, and the impact of poloidally asymmetric impurity density and natural line broadening is discussed in the context of the planned ITER x-ray crystal spectrometer.

Reinke, M. L.; Podpaly, Y. A.; Hutchinson, I. H.; Rice, J. E.; Gao, C.; Greenwald, M.; Howard, N. T.; Hubbard, A.; Hughes, J. W.; White, A. E.; Wolfe, S. M. [MIT-Plasma Science and Fusion Center, Cambridge, Massachusetts 02139 (United States); Bitter, M.; Delgado-Aparicio, L.; Hill, K.; Pablant, N. [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States)

2012-11-15T23:59:59.000Z

190

Using Light to Control How X Rays Interact with Matter  

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

ultrafast x-ray spectroscopy. ALS femtosecond spectroscopy beamline layout. Femtosecond x-ray and laser pulses derive from a single 800-nm laser oscillator. Femtosecond x rays...

191

X-ray Photoelectron Spectroscopy of GaP{1-x}N(x) Photocorroded as a Result of Hydrogen Production through Water Electrolysis  

E-Print Network (OSTI)

X-ray Photoelectron Spectroscopy of GaP{1-x}N(x) Photocorroded as a Result of Hydrogen Production through Water Electrolysis

Mayer, Marie A

2006-01-01T23:59:59.000Z

192

Ultrafast X-Ray Spectroscopy as a Probe of Nonequilibrium Dynamics in  

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

The Electronic Origin of Photoinduced Strain The Electronic Origin of Photoinduced Strain Modifying Proteins to Combat Disease Higher Temperature at the Earth's Core Clues about Rheumatoid Arthritis Damage Science Highlights Archives: 2013 | 2012 | 2011 | 2010 2009 | 2008 | 2007 | 2006 2005 | 2004 | 2003 | 2002 2001 | 2000 | 1998 | Subscribe to APS Science Highlights rss feed Ultrafast X-Ray Spectroscopy as a Probe of Nonequilibrium Dynamics in Ruthenium Complexes FEBRUARY 8, 2013 Bookmark and Share Copyright © 2012 Elsevier B.V. All rights reserved. Exciting the atoms or molecules of a substance via the use of visible light, or photoexcitation, can play a significant role in a range of energy-conversion processes, such as natural photosynthesis (oxygen from water) and manmade solar cells (electricity from sunlight). But a better

193

Atomic-scale chemical quantification of oxide interfaces using energy-dispersive X-ray spectroscopy  

SciTech Connect

Atomic-scale quantification of chemical composition across oxide interfaces is important for understanding physical properties of epitaxial oxide nanostructures. Energy-dispersive X-ray spectroscopy (EDS) in an aberration-corrected scanning transmission electron microscope was used to quantify chemical composition across the interface of ferromagnetic La{sub 0.7}Sr{sub 0.3}MnO{sub 3} and antiferromagnetic BiFeO{sub 3} quantum structure. This research demonstrates that chemical composition at atomic columns can be quantified by Gaussian peak-fitting of EDS compositional profiles across the interface. Cation diffusion was observed at both A- and B-sublattice sites; and asymmetric chemical profiles exist across the interface, consistent with the previous studies.

Lu, Ping; Van Benthem, Mark [Sandia National Laboratories, P.O. Box 5800, MS 1411, Albuquerque, New Mexico 87185-1411 (United States)] [Sandia National Laboratories, P.O. Box 5800, MS 1411, Albuquerque, New Mexico 87185-1411 (United States); Xiong, Jie; Jia, Quanxi [Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)] [Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

2013-04-29T23:59:59.000Z

194

Ga configurations in hydrogenated amorphous silicon as studied by x-ray photoemission spectroscopy  

Science Journals Connector (OSTI)

Samples of crystalline silicon and glow-discharge-deposited hydrogenated amorphous silicon were doped with gallium by low-energy (4-keV) ion implantation. X-ray photoemission spectroscopy was used to study the chemical-bonding states of the Ga. From Ga 3d core-level studies, we found that elementary interstitial, threefold-coordinated, and fourfold-coordinated Ga coexist in the ion-implanted and annealed amorphous silicon network. The percentage of activated threefold- and fourfold-coordinated Ga atoms is found to increase with increasing annealing temperature, prior to crystallization. The energy released by the amorphous silicon lattice upon annealing contributes to the activation of the gallium from the elementary state to the threefold- or fourfold-coordinated state. No evidence of Ga-H bond formation is found. The percentage of fourfold-coordinated Ga, which we call the doping efficiency, ranges from 5% to 10%, depending upon the thermal treatment.

Z. H. Lu; S. Poulin-Dandurand; E. Sacher; A. Yelon

1990-09-15T23:59:59.000Z

195

X-ray photoelectron spectroscopy analysis of organic materials etched by charged water droplet impact  

SciTech Connect

Electrospray droplet impact (EDI) has been developed for matrix-free secondary ion mass spectrometry for surface analysis. When a target is etched by EDI, the physical etching on the target is suppressed to minimal, i.e., the occurrence of shallow surface etching. A novel approach to shallow surface etching of polystyrene (PS) by EDI was investigated. The charged water droplets were irradiated to a bulk and a spin coated PS. After irradiation, these samples were analyzed by X-ray photoelectron spectroscopy (XPS) and atomic force microscopy. It was found that XPS spectra for PS were independent on the irradiation time by EDI. This indicates that EDI is a unique technique for the surface etching of the organic materials without leaving any damage on the etched surface.

Sakai, Yuji; Iijima, Yoshitoki; Takaishi, Riou; Asakawa, Daiki; Hiraoka, Kenzo [Clean Energy Research Center, University of Yamanashi, Takeda 4-3-11, Kofu 400-8511, Japan and Japan Science and Technology Agency Innovation Satellite, Shizuoka, 3-5-1 Johoku, Nakaku, Hamamatsu 432-8561 (Japan); Electron Optics Sales Division, JEOL Ltd., 2-8-3 Akebono, Tachikawa, Tokyo 190-0012 (Japan); Clean Energy Research Center, University of Yamanashi, Takeda 4-3-11, Kofu 400-8511 (Japan)

2009-07-15T23:59:59.000Z

196

Delocalization and occupancy effects of 5f orbitals in plutonium intermetallics using L3-edge resonant X-ray emission spectroscopy  

SciTech Connect

Although actinide (An) L3 -edge X-ray absorption near-edge structure (XANES) spectroscopy has been very effective in determining An oxidation states in insulating, ionically bonded materials, such as in certain coordination compounds and mineral systems, the technique fails in systems featuring more delocalized 5f orbitals, especially in metals. Recently, actinide L3-edge resonant X-ray emission spec- troscopy (RXES) has been shown to be an effective alternative. This technique is further demonstrated here using a parameterized partial unoccupied density of states method to quantify both occupancy and delocalization of the 5f orbital in ?-Pu, ?-Pu, PuCoGa5 , PuCoIn5 , and PuSb2. These new results, supported by FEFF calculations, highlight the effects of strong correlations on RXES spectra and the technique?s ability to differentiate between f-orbital occupation and delocalization.

Booth, C. H.; Medling, S. A.; Jiang, Yu; Bauer, E. D.; Tobash, P. H.; Mitchell, J. N.; Veirs, D. K.; Wall, M. A.; Allen, P. G.; Kas, J. J.; Sokaras, D.; Nordlund, D.; Weng, T.-C.

2014-06-24T23:59:59.000Z

197

Broadband spectroscopy of the eclipsing high mass X-ray binary 4U 1700-37 with Suzaku  

E-Print Network (OSTI)

We present the results obtained from broadband spectroscopy of the high mass X-ray binary 4U 1700-37 using data from a Suzaku observation in 2006 September 13-14 covering 0.29-0.72 orbital phase range. The light curves showed significant and rapid variation in source flux during entire observation. We did not find any signature of pulsations in the light curves. However, a quasi-periodic oscillation at ~20 mHz was detected in the power density spectrum of the source. The 1-70 keV spectrum was fitted with various continuum models. However, we found that the partially absorbed high energy cutoff power-law and Negative and Positive power-law with Exponential cutoff (NPEX) models described the source spectrum well. Iron emission lines at 6.4 keV and 7.1 keV were detected in the source spectrum. An absorption like feature at ~39 keV was detected in the residuals while fitting the data with NPEX model. Considering the feature as cyclotron absorption line, the surface magnetic field of the neutron star was estimated...

Jaisawal, Gaurava K

2015-01-01T23:59:59.000Z

198

First-principles core-level X-ray photoelectron spectroscopy calculation on arsenic defects in silicon crystal  

SciTech Connect

We investigate the X-ray photoelectron spectroscopy (XPS) binding energies of As 3d in Si for various defects in neutral and charged states by first-principles calculation. It is found that the complexes of a substitutional As and a vacancy in charged and neutral states explain the experimentally observed unknown peak very well.

Kishi, Hiroki; Miyazawa, Miki; Matsushima, Naoki; Yamauchi, Jun [Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Yokohama-shi, Kanagawa-ken 223-8522 (Japan)

2014-02-21T23:59:59.000Z

199

Cryogenic growth of Al nitride on GaAs(110): X-ray-photoemission spectroscopy and inverse-photoemission spectroscopy  

Science Journals Connector (OSTI)

We report on our recent studies of Al nitride growth on GaAs(110) formed by depositing Al onto a condensed ammonia overlayer on GaAs(110) at T=90 K using x-ray-photoemission spectroscopy and inverse-photoemission spectroscopy. We have also investigated the temperature dependence of the interface thus formed. The results show some limited amount of Al nitride formed at T=90 K even though the reaction is slow, but the overlayer mostly remains metallic until the substrate is heated up. Much of the reaction of Al with ammonia occurs at about T=170 K, above which the overlayer becomes insulating. The combined information from occupied and unoccupied states reveals new features of the interface formation, and is consistent with our previous synchrotron photoemission studies of Al/NH3/GaAs(100).

Ken T. Park and Y. Gao

1993-02-15T23:59:59.000Z

200

Determination of lead in gasoline by atomic absorption spectroscopy  

Science Journals Connector (OSTI)

A procedure has been developed for the direct determination of lead in gasoline by atomic absorption spectroscopy. This procedure is rapid, does not require expensive equipment, is remarkably free from interference by other trace elements present, and allows considerable variation in the sulfur and nitrogen content of the gasoline. It compares favorably with other existing procedures for this determination, such as X-ray fluorescence, wet chemical methods, and flame photometry.

J.W. Robinson

1961-01-01T23:59:59.000Z

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201

THREE NEW GALACTIC CENTER X-RAY SOURCES IDENTIFIED WITH NEAR-INFRARED SPECTROSCOPY  

SciTech Connect

We have conducted a near-infrared spectroscopic survey of 47 candidate counterparts to X-ray sources discovered by the Chandra X-Ray Observatory near the Galactic center (GC). Though a significant number of these astrometric matches are likely to be spurious, we sought out spectral characteristics of active stars and interacting binaries, such as hot, massive spectral types or emission lines, in order to corroborate the X-ray activity and certify the authenticity of the match. We present three new spectroscopic identifications, including a Be high-mass X-ray binary (HMXB) or a ? Cassiopeiae (Cas) system, a symbiotic X-ray binary, and an O-type star of unknown luminosity class. The Be HMXB/? Cas system and the symbiotic X-ray binary are the first of their classes to be spectroscopically identified in the GC region.

DeWitt, Curtis [Department of Physics, University of California, Davis, CA 95616 (United States); Bandyopadhyay, Reba M.; Eikenberry, Stephen S.; Sarajedini, Ata [Department of Astronomy, University of Florida, 211 Bryant Space Center, P.O. Box 112055, Gainesville, FL 32611 (United States); Sellgren, Kris [Department of Astronomy, The Ohio State University, 140 West 18th Avenue, Columbus, OH 43210 (United States); Blum, Robert; Olsen, Knut [National Optical Astronomy Observatories, Tucson, AZ 85719 (United States); Bauer, Franz E., E-mail: curtis.n.dewitt@nasa.gov [Departamento de Astronomía y Astrofísica, Pontificia Universidad Católica de Chile, Casilla 306, Santiago 22 (Chile)

2013-11-01T23:59:59.000Z

202

Combined energy dispersive EXAFS and x?ray diffraction  

Science Journals Connector (OSTI)

An in situ experiment to measure both x?ray absorption spectroscopy and x?ray diffraction of aurichalcite is described. The experiment uses position sensitive detectors to enable both data sets to be collected while the sample is slowly decomposed in air and then reduced in hydrogen. ?

A. J. Dent; M. P. Wells; R. C. Farrow; C. A. Ramsdale; G. E. Derbyshire; G. N. Greaves; J. W. Couves; J. M. Thomas

1992-01-01T23:59:59.000Z

203

Oxygen Abundances in the Milky Way Using X-ray Absorption Measurements Towards Galaxy Clusters  

E-Print Network (OSTI)

We present measurements of the oxygen abundance of the Milky Way's ISM by observing the K-shell X-ray photoionization edge towards galaxy clusters. This effect is most easily observed towards objects with galactic columns (n_H) of a few times 1e21 cm^-2. We measure X-ray column densities towards 11 clusters and find that at high galactic columns above approximately 1e21 cm^-2 the X-ray columns are generally 1.5--3.0 times greater than the 21 cm H II columns, indicating that molecular clouds become an important contributor to n_H at higher columns. We find the average ISM oxygen abundance to be (O/H) = (4.85 +/- 0.06) x 10^-4, or 0.99 solar when using the most recent solar photospheric values. Since X-ray observations are sensitive to the total amount of oxygen present (gas + dust), these results indicate a high gas to dust ratio. Also, the oxygen abundances along lines of sight through high galactic columns (n_H) are the same as abundances through low columns, suggesting that the composition of denser clouds is similar to that of the more diffuse ISM.

Wayne H. Baumgartner; Richard F. Mushotzky

2005-09-21T23:59:59.000Z

204

(Research at and operation of the material science x-ray absorption beamline (X-11) at the National Synchrotron Light Source)  

SciTech Connect

This report discusses three projects at the Material Science X-Ray Absorption Beamline. Topics discussed include: XAFS study of some titanium silicon and germanium compounds; initial XAS results of zirconium/silicon reactions; and low angle electron yield detector.

Not Available

1992-01-01T23:59:59.000Z

205

[Research at and operation of the material science x-ray absorption beamline (X-11) at the National Synchrotron Light Source]. Progress report  

SciTech Connect

This report discusses three projects at the Material Science X-Ray Absorption Beamline. Topics discussed include: XAFS study of some titanium silicon and germanium compounds; initial XAS results of zirconium/silicon reactions; and low angle electron yield detector.

Not Available

1992-08-01T23:59:59.000Z

206

PHYSICAL REVIE% B VOLUME 22, NUMBER 6 15 SEPTEMBER 1980 Ab initio studies of the x-ray absorption edge in copper complexes.  

E-Print Network (OSTI)

PHYSICAL REVIE% B VOLUME 22, NUMBER 6 15 SEPTEMBER 1980 Ab initio studies of the x-ray absorption calcula- tions on a model copper complex in order to eluci- 22 2767 O1980 The American Physical Society

Goddard III, William A.

207

CHARACTERIZATION OF THE LOCAL TITANIUM ENVIRONMENT IN DOPED SODIUM ALUMINUM HYDRIDE USING X-RAY ADSORPTION SPECTROSCOPY.  

SciTech Connect

Ti K-edge x-ray absorption spectroscopy was used to explore the local titanium environment and valence in 2-4 mol% Ti-doped sodium alanate. An estimate of the oxidation state of the dopant, based upon known standards, revealed a zero-valent titanium atom. An analysis of the near-edge and extended fine structures indicates that the Ti does not enter substitutional or interstitial sites in the NaAlH{sub 4} lattice. Rather, the Ti is located on/near the surface and is coordinated by 10.2 {+-} 1 aluminum atoms with an interatomic distance of 2.82 {+-} 0.01 {angstrom}, similar to that of TiAl{sub 3}. The Fourier transformed EXAFS spectra reveals a lack of long-range order around the Ti dopant indicating that the Ti forms nano-clusters of TiAl{sub 3}. The similarity of the spectra in the hydrided and dehydrided samples suggests that the local Ti environment is nearly invariant during hydrogen cycling.

GRAETZ, J.; IGNATOV, A. YU; TYSON, T.A.; REILLY, J.J.; JOHNSON, J.

2004-11-30T23:59:59.000Z

208

Phase resolved X-ray spectroscopy of HDE288766: Probing the wind of an extreme Of+/WNLha star  

E-Print Network (OSTI)

HDE228766 is a very massive binary system hosting a secondary component, which is probably in an intermediate evolutionary stage between an Of supergiant and an WN star. The wind of this star collides with the wind of its O8 II companion, leading to relatively strong X-ray emission. Measuring the orbital variations of the line-of-sight absorption toward the X-ray emission from the wind-wind interaction zone yields information on the wind densities of both stars. X-ray spectra have been collected at three key orbital phases to probe the winds of both stars. Optical photometry has been gathered to set constraints on the orbital inclination of the system. The X-ray spectra reveal prominent variations of the intervening column density toward the X-ray emission zone, which are in line with the expectations for a wind-wind collision. We use a toy model to set constraints on the stellar wind parameters by attempting to reproduce the observed variations of the relative fluxes and wind optical depths at 1 keV. The lac...

Rauw, G; Naze, Y; Eenens, P; Manfroid, J; Flores, C A

2014-01-01T23:59:59.000Z

209

MULTI-WAVELENGTH STUDIES OF SPECTACULAR RAM PRESSURE STRIPPING OF A GALAXY: DISCOVERY OF AN X-RAY ABSORPTION FEATURE  

SciTech Connect

We report the detection of an X-ray absorption feature near the galaxy M86 in the Virgo cluster. The absorber has a column density of 2-3 × 10{sup 20} cm{sup –2}, and its position coincides with the peak of an intracluster H I cloud which was removed from the galaxy NGC 4388 presumably by ram pressure. These results indicate that the H I cloud is located in front of M86 along the line-of-sight, and suggest that the stripping was primarily created by an interaction between NGC 4388 and the hot plasmas of the Virgo cluster, not the M86 halo. By calculating an X-ray temperature map, we further detected an X-ray counterpart of the H I cloud up to ?3' south of M86. It has a temperature of 0.89 keV and a mass of ?4.5 × 10{sup 8} M {sub ?}, exceeding the estimated H I gas mass. The high hot-to-cold gas ratio in the cloud indicates a significant evaporation of the H I gas, probably by thermal conduction from the hotter cluster plasma with a sub-Spitzer rate.

Gu, Liyi; Makishima, Kazuo [Research Center for the Early Universe, School of Science, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan)] [Research Center for the Early Universe, School of Science, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan); Yagi, Masafumi [Optical and Infrared Astronomy Division, National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan)] [Optical and Infrared Astronomy Division, National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan); Nakazawa, Kazuhiro [Department of Physics, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan)] [Department of Physics, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan); Yoshida, Michitoshi [Hiroshima Astrophysical Science Center, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526 (Japan)] [Hiroshima Astrophysical Science Center, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526 (Japan); Fujita, Yutaka [Department of Earth and Space Science, Graduate School of Science, Osaka University, 1-1 Machikaneyama-cho, Toyonaka, Osaka 560-0043 (Japan)] [Department of Earth and Space Science, Graduate School of Science, Osaka University, 1-1 Machikaneyama-cho, Toyonaka, Osaka 560-0043 (Japan); Hattori, Takashi [Subaru Telescope, National Astronomical Observatory of Japan, 650 North A'Ohoku Place, Hilo, HI 96720 (United States)] [Subaru Telescope, National Astronomical Observatory of Japan, 650 North A'Ohoku Place, Hilo, HI 96720 (United States); Akahori, Takuya, E-mail: lygu@juno.phys.s.u-tokyo.ac.jp [Sydney Institute for Astronomy, School of Physics, The University of Sydney, NSW 2006 (Australia)] [Sydney Institute for Astronomy, School of Physics, The University of Sydney, NSW 2006 (Australia)

2013-11-10T23:59:59.000Z

210

Electronic structure and x-ray photoelectron spectroscopy of the ?, ?, and ? phases of Np  

Science Journals Connector (OSTI)

The electronic structure, density of states, and x-ray photoelectron spectroscopy (XPS) intensities of the ?, ?, and ? phases of Np have been theoretically determined from self-consistent, fully relativistic, linear muffin-tin-orbital band-structure calculations. The calculated XPS intensities show a large f peak that narrows (due to the larger volumes per atom) and moves closer to the Fermi energy as one progresses through the ?, ?, and ? phases. Experimental XPS intensities of the ? and ? phases are also presented and compared to the theoretical calculations. Experimentally, the ? and ? intensities are found to be almost identical, and do not show any evidence for the theoretically predicted f-band narrowing. In addition, there is a large additional experimental intensity at higher binding energy that is not present in the calculations. This extra intensity may be evidence for quasilocalized behavior of the 5f electronic states that is induced by the XPS process. For example, the low-energy tail may be related to either multiplet or satellite structure due to final-state localized atomiclike correlation effects. © 1996 The American Physical Society.

R. C. Albers; A. M. Boring; J. M. Wills; L. E. Cox; O. E. Eriksson; N. E. Christensen

1996-11-15T23:59:59.000Z

211

Extended x-ray absorption fine structure studies on the iron-containing subunit of ribunucleotide reductase from Escherichia coli  

SciTech Connect

Iron K-edge X-ray absorption spectra were obtained on the protein B2, the small subunit of ribonucleotide reductase from Escherichia coli. Protein B2 contains a binuclear iron center with many properties in common with the iron center of oxidized hemerythrins. The extended x-ray absorption fine structure (EXAFS) measurements on protein B2 were analyzed and compared with published data for oxyhemerythrin. In protein B2 there are, in the first coordination shell around each Fe atom, five or six oxygen or nitrogen atoms that are directly coordinated ligands. In oxyhemerythrin there are six ligands to each iron. As in oxyhemerythrin, one of the ligands in the first shell of protein B2 is at a short distance, about 1.78 A, confirming the existence of a ..mu..-oxo bridge. The other atoms of the first shell are at an average distance of 2.04 A, which is about 0.1 A shorter than in oxyhemerythrin. In protein B2 the Fe-Fe distance is in the range 3.26-3.48 A, and the bridging angle falls between 130 and 150/sup 0/. On the basis of these data, there is no direct evidence for any histidine ligands in protein B2, but the noise level leaves way for the possibility of a maximum of about three histidines for each Fe pair. The x-ray absorption spectrum of a hydroxyurea-treated sample was not significantly different from that of the native protein B2, which implies that no significant alteration in the structure of the iron site occurs upon destruction of the tyrosine radical.

Bunker, G.; Petersson, L.; Sjoeberg, B.M.; Sahlin, M.; Chance, M.; Chance, B.; Ehrenberg, A.

1987-07-28T23:59:59.000Z

212

Resonant Soft X-Ray Scattering - Combining Structural with Spectroscopic  

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

Resonant Soft X-Ray Scattering - Combining Structural with Spectroscopic Resonant Soft X-Ray Scattering - Combining Structural with Spectroscopic Refinement Friday, September 28, 2012 - 10:00am SLAC, Bldg. 137, Room 322 SSRL Presents Kevin Stone X-ray absorption spectroscopy has become an important tool in understanding the electronic structure of materials. Resonant absorption edges in the soft x-ray regime are especially interesting as they allow the study of the lighter elements, such as in organic or organo-metallic substances, as well as important L-edges of the 3d transition metals important in magnetic and oxide systems. Measurements of soft x-ray absorption spectra are inherently surface sensitive, and are plagued by issues such as extinction (in electron yield measurements) or self absorption (in fluorescence yield

213

Picosecond soft x-ray absorption measurement of the photoinduced insulator-to-metal transition in VO2  

Science Journals Connector (OSTI)

We directly measure the photoinduced insulator-to-metal transition in VO2 using time-resolved near-edge x-ray absorption. Picosecond pulses of synchrotron radiation are used to detect the redshift in the vanadium L3 edge at 516 eV, which is associated with the transient collapse of the low-temperature band gap. We identify a two-component temporal response, corresponding to an ultrafast transformation over a 50 nm surface layer, followed by 40 m/s thermal growth of the metallic phase into the bulk.

A. Cavalleri, H. H. W. Chong, S. Fourmaux, T. E. Glover, P. A. Heimann, J. C. Kieffer, B. S. Mun, H. A. Padmore, and R. W. Schoenlein

2004-04-28T23:59:59.000Z

214

X-ray spectroscopy in mammography with a silicon PIN photodiode with application to the measurement of tube voltage  

SciTech Connect

In this work a silicon PIN photodiode was employed in mammographic x-ray spectroscopy under clinical and nonclinical conditions. Measurements have been performed at a constant potential tungsten anode tube, adapted in this work with molybdenum filters to produce a beam like that used in mammography, and at a clinical equipment with a molybdenum anode tube by using an additional aluminum filtration. The corrected x-ray spectra were in full agreement with those generated by theoretical models published in the literature and agree well with those measured with a CdZnTe detector for tube voltages less than 30 kV. The half value layer and the relative exposure values calculated from the corrected silicon PIN photodiode spectra were in agreement with those measured with an ionization chamber. These results indicate that a silicon PIN photodiode are very suitable for mammographic x-ray spectroscopy. As an application, the voltage (kV) applied to mammographic x-ray equipment has been measured through the evaluation of the spectra high energy cut off. Uncertainties evaluated for the voltage values calculated from the measured spectra are less than 0.13% for voltages in the range 20-35 kV. The low uncertainties associated with the obtained results in this work point out that the method employed can be accurately used for calibration of noninvasive mammographic kVp meters.

Kuenzel, Roseli; Herdade, Silvio Bruni; Terini, Ricardo Andrade; Costa, Paulo Roberto [Instituto de Fisica, Universidade de Sao Paulo, Rua do Matao, Travessa R, 187, Cidade Universitaria, CEP 05508-900, Sao Paulo, Sao Paulo (Brazil); Departamento de Fisica, Pontificia Universidade Catolica de Sao Paulo, R. Marques de Paranagua, 111, Consolacao, CEP 01303-050, Sao Paulo, Sao Paulo (Brazil); Secao Tecnica de Desenvolvimento Tecnologico em Saude, Instituto de Electrotecnica e Energia, Universidade de Sao Paulo, Avenida Professor Luciano Gualberto, 1289, Cidade Universitaria, CEP 05508-010, Sao Paulo (Brazil)

2004-11-01T23:59:59.000Z

215

Soft X-ray emission spectroscopy of liquids and lithium batterymaterials  

SciTech Connect

Lithium ion insertion into electrode materials is commonly used in rechargeable battery technology. The insertion implies changes in both the crystal structure and the electronic structure of the electrode material. Side-reactions may occur on the surface of the electrode which is exposed to the electrolyte and form a solid electrolyte interface (SEI). The understanding of these processes is of great importance for improving battery performance. The chemical and physical properties of water and alcohols are complicated by the presence of strong hydrogen bonding. Various experimental techniques have been used to study geometrical structures and different models have been proposed to view the details of how these liquids are geometrically organized by hydrogen bonding. However, very little is known about the electronic structure of these liquids, mainly due to the lack of suitable experimental tools. In this thesis examples of studies of lithium battery electrodes and liquid systems using soft x-ray emission spectroscopy will be presented. Monochromatized synchrotron radiation has been used to accomplish selective excitation, in terms of energy and polarization. The electronic structure of graphite electrodes has been studied, before and after lithium intercalation. Changes in the electronic structure upon lithiation due to transfer of electrons into the graphite {pi}-bands have been observed. Transfer of electrons in to the 3d states of transition metal oxides upon lithiation have been studied, through low energy excitations as dd- and charge transfer-excitations. A SEI was detected on cycled graphite electrodes. By the use of selective excitation different carbon sites were probed in the SEI. The local electronic structure of water, methanol and mixtures of the two have been examined using a special liquid cell, to separate the liquid from the vacuum in the experimental chamber. Results from the study of liquid water showed a strong influence on the 3a1 molecular orbital and orbital mixing between water molecules upon hydrogen bonding. Apart from the four-hydrogen-bonding structure in water, a structure where one hydrogen bond is broken could be separated and identified. The soft x-ray emission study of methanol showed the existence of ring and chain formations in the liquid phase and the dominating structures are formed of 6 and 8 molecules. Upon mixing of the two liquids, a segregation at the molecular level was found and the formation of new structures, which could explain the unexpected low increase of the entropy.

Augustsson, Andreas

2004-10-27T23:59:59.000Z

216

VARIOUS APPLICATIONS OF ZEEMAN ATOMIC ABSORPTION SPECTROSCOPY  

E-Print Network (OSTI)

APPLICATIONS OF ZEEMAN ATOMIC ABSORPTION SPECTROSCOPYthe Zeeman effect to atomic absorption spectroscopy has beenthe Zeeman effect on atomic absorption spectrometry has been

Koizumi, Hideaki

2011-01-01T23:59:59.000Z

217

X-ray absorption spectroscopic studies of the dinuclear iron center in methane monooxygenase and the sulfure and chlorine centers in photographic materials  

SciTech Connect

The dinuclear iron center of the hydroxylase component of soluble methane monooxygenase (MMO) from Methylococcus capsulatus and Methylosinus trichosporiwn has been studied by X-ray absorption spectroscopy. Analysis of the Fe K-edge EXAFS revealed that the first shell coordination of the Fe(HI)Fe(IH) oxidized state of the hydroxylase from M. capsulatus consists of approximately 6 N and 0 atoms at an average distance of 2.04 [Angstrom]. The Fe-Fe distance was determined to be 3.4 [Angstrom]. No evidence for the presence of a short oxo bridge in the iron center of the oxidized hydroxylase was found, suggesting that the active site of MMO is significantly different from the active sites of the dinuclear iron proteins hemery and ribonucleotide reductase. In addition, the results of the first shell fits suggest that there are more oxygen than nitrogen donor ligands.

DeWitt, J.G.

1992-12-01T23:59:59.000Z

218

X-ray absorption spectroscopic studies of the dinuclear iron center in methane monooxygenase and the sulfure and chlorine centers in photographic materials  

SciTech Connect

The dinuclear iron center of the hydroxylase component of soluble methane monooxygenase (MMO) from Methylococcus capsulatus and Methylosinus trichosporiwn has been studied by X-ray absorption spectroscopy. Analysis of the Fe K-edge EXAFS revealed that the first shell coordination of the Fe(HI)Fe(IH) oxidized state of the hydroxylase from M. capsulatus consists of approximately 6 N and 0 atoms at an average distance of 2.04 {Angstrom}. The Fe-Fe distance was determined to be 3.4 {Angstrom}. No evidence for the presence of a short oxo bridge in the iron center of the oxidized hydroxylase was found, suggesting that the active site of MMO is significantly different from the active sites of the dinuclear iron proteins hemery and ribonucleotide reductase. In addition, the results of the first shell fits suggest that there are more oxygen than nitrogen donor ligands.

DeWitt, J.G.

1992-12-01T23:59:59.000Z

219

UV-Raman spectroscopy, X-ray photoelectron spectroscopy, and temperature programmed desorption studies of model and bulk heterogeneous catalysts  

SciTech Connect

X-ray photoelectron spectroscopy (XPS) and Temperature Programmed Desorption (TPD) have been used to investigate the surface structure of model heterogeneous catalysts in ultra-high vacuum (UHV). UV-Raman spectroscopy has been used to probe the structure of bulk model catalysts in ambient and reaction conditions. The structural information obtained through UV-Raman spectroscopy has been correlated with both the UHV surface analysis and reaction results. The present day propylene and ethylene polymerization catalysts (Ziegler-Natta catalysts) are prepared by deposition of TiCl{sub 4} and a Al(Et){sub 3} co-catalyst on a microporous Mg-ethoxide support that is prepared from MgCl{sub 2} and ethanol. A model thin film catalyst is prepared by depositing metallic Mg on a Au foil in a UHV chamber in a background of TiCl{sub 4} in the gas phase. XPS results indicate that the Mg is completely oxidized to MgCl{sub 2} by TiCl{sub 4} resulting in a thin film of MgCl{sub 2}/TiCl{sub x}, where x = 2, 3, and 4. To prepare an active catalyst, the thin film of MgCl{sub 2}/TiCl{sub x} on Au foil is enclosed in a high pressure cell contained within the UHV chamber and exposed to {approx}1 Torr of Al(Et){sub 3}.

Tewell, Craig R.

2002-08-19T23:59:59.000Z

220

Center for X-Ray Optics, 1991  

SciTech Connect

This report discusses: Soft-X-Ray imaging with zone-plate lenses; multilayer reflective optics; and spectroscopy with x-rays.

Not Available

1992-03-01T23:59:59.000Z

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


221

High-Resolution Structure of the Photosynthetic Mn4Ca Catalyst from X-ray Spectroscopy  

E-Print Network (OSTI)

the Photosynthetic Mn 4 Ca Catalyst from X-ray Spectroscopystructure of the Mn 4 Ca catalyst at high-resolution whichthe structure of Mn 4 Ca catalyst as it cycles through the

Yano, Junko

2008-01-01T23:59:59.000Z

222

Magnetic x-ray scattering at the M{sub 5} absorption edge of Ho  

SciTech Connect

Magnetic x-ray scattering from thin Ho-metal films at M{sub 5} resonance reveals atomic scattering lengths up to 200r{sub 0}--i.e., of the same order of magnitude as predicted theoretically by Hannon et al. [Phys. Rev. Lett. 61, 1245 (1988)]. The photon-energy dependence of first- and second-order magnetic satellites allows a straightforward identification of circular and linear dichroic contributions. A direct comparison to magnetic neutron scattering demonstrates the potential of the method for studies of complex magnetic structures in ultrathin films and highly diluted materials.

Ott, H.; Schierle, E.; Grigoriev, A. Yu.; Kaindl, G.; Weschke, E. [Institut fuer Experimentalphysik, Freie Universitaet Berlin, Arnimallee 14, D-14195 Berlin-Dahlem (Germany); Schuessler-Langeheine, C. [Institut fuer Experimentalphysik, Freie Universitaet Berlin, Arnimallee 14, D-14195 Berlin-Dahlem (Germany); II. Physikalisches Institut, Universitaet zu Koeln, Zuelpicher Str. 77, D-50937 Koeln (Germany); Leiner, V. [Institut fuer Experimentalphysik/Festkoerperphysik, Ruhr-Universitaet Bochum, D-44780 Bochum (Germany); Institut fuer Werkstoffforschung, WFN, GKSS Forschungszentrum, D-21502 Geesthacht (Germany); Zabel, H. [Institut fuer Experimentalphysik/Festkoerperphysik, Ruhr-Universitaet Bochum, D-44780 Bochum (Germany)

2006-09-01T23:59:59.000Z

223

Characterization of Pt/Al/sub 2/O/sub 3/ catalysts by extended X-ray absorption fine structure  

SciTech Connect

Three different Pt/Al/sub 2/O/sub 3/ catalysts with average crystallite sizes of 95, 26, and 8 A., as assessed by hydrogen chemisorption measurements, and reference samples of platimum foil and PtO/sub 2/ were examined by transmission X-ray absorption measurements near the Pt L/sub I//sub I//sub I/ X-ray absorption edge. The fine structure for the reduced catalysts showed that the first Pt-Pt interatomic separation distance in the crystallites did not change with crystallite size. The 95 and 26 A. catalysts had Pt crystallites with fcc crystal structure, the same as in bulk platimum. Adsorption of carbon monoxide on the 26 A. catalyst at room temperature did not disturb crystallite structure, but oxygen chemisorption on that catalyst significantly reduced the magnitude of the first Pt-Pt peak, implying a reduction in the average number of first-nearest-neighbor Pt atoms. The Fourier transform indicated coordination of Pt atoms with oxygen. All Pt-Pt bands vanished when the 8 A. catalyst was exposed to oxygen. Platimum atom electron deficiency decreased significantly after carbon monoxide or oxygen adsorption on the catalysts.

Lornston, J.M.

1980-01-01T23:59:59.000Z

224

Electronic Structure of Hemin in Solution Studied by Resonant X-ray Emission Spectroscopy and Electronic Structure Calculations  

Science Journals Connector (OSTI)

Electronic Structure of Hemin in Solution Studied by Resonant X-ray Emission Spectroscopy and Electronic Structure Calculations ... (20) Transition energies and moments for L-edges were calculated with DFT/ROCIS using the same basis set. ... Character of MOs of the Single-Point DFT Calculations Illustrating the Mixing of the Iron d-Orbitals in FePPIX Chloride As Inferred from Restricted Open-Shell Single-Point DFT Calculation, Combined with Löwdin Population Analysis ...

Kaan Atak; Ronny Golnak; Jie Xiao; Edlira Suljoti; Mika Pflüger; Tim Brandenburg; Bernd Winter; Emad F. Aziz

2014-07-28T23:59:59.000Z

225

Experimental Results and Modeling of Low-Heat-Capacity TES Microcalorimeters for Soft-X-ray Spectroscopy  

SciTech Connect

Transition-edge-sensor (TES) X-ray microcalorimeters have mostly been targeted at mid-band energies from 0.05-10 keV and high energies to above 100 keV. However, many other optimizations are possible. Here we present results from devices optimized for soft X-ray applications. For spectroscopy below 1 keV, the X-ray stopping power and heat capacity (C) of the TES itself are high enough that we can omit a separate absorber. The resulting devices have low C and the best-achievable energy resolution should be under 1 eV. We are interested in pursuing such devices primarily for astrophysical applications and laboratory astrophysics at LLNL's Electron-Beam Ion Trap. To this end, we have studied arrays in which 'bare' TESs are interspersed with broad-band pixels that have absorbers. By extending the absorbers to cover the area where the leads contact the low-energy pixels, we have eliminated a significant source of non-Gaussian detector response. The bare devices are in a different regime from our typical devices in that C is ten times lower and the conductance to the bath is four times lower. We have explored this regime through simultaneous fitting of noise and impedance data. These data cannot be fit by the simple model we employ to describe our typical broad-band devices. In this contribution we present X-ray spectra and the results from modeling.

Eckart, Megan E. [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); NASA Postdoctoral Program Fellow (United States); Adams, Joseph S.; Smith, Stephen J. [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); CRESST and University of Maryland, Baltimore County, MD 21250 (United States); Bandler, Simon R. [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); CRESST and University of Maryland, College Park, MD 20742 (United States); Brekosky, Regis P.; Chervenak, James A.; Finkbeiner, Fred M.; Kelley, Richard L.; Kilbourne, Caroline A.; Scott Porter, F.; Sadleir, John E. [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)

2009-12-16T23:59:59.000Z

226

Soft x-ray appearance potential spectroscopy study of MgO (100) and ?-Al{sub 2}O{sub 3} (100) single crystals  

SciTech Connect

Soft x-ray appearance potential spectroscopy (SXAPS) measurements was used to measure on MgO (100) and ?-Al{sub 2}O{sub 3} (100) single crystals. Mg 1s, Al 1s, and O 1s SXAPS self-deconvoluted (SD) spectra were obtained. The features of the Mg 1s and O1s SD spectra are in fair agreement with those of the near-edge x-ray absorption fine structure spectra for an MgO thin film (3 ML) on Ag (100). This suggests that the SXAPS spectra reflect electronic states of the relaxed MgO (100) surface. The features of the Al 1s and O 1s SD spectra are in qualitative agreement with those of the electron energy-loss spectroscopy. The SXAPS SD spectra are discussed in terms of antibonding states and partial density of empty states obtained by theoretical calculations for MgO and ?-Al{sub 2}O{sub 3,} respectively. The present result suggests that the “approximate dipole selection rule” is applicable to the SXAPS spectra of MgO and ?-Al{sub 2}O{sub 3}, as well as 3d transition metal oxides.

Fukuda, Yasuo, E-mail: royfuku@rie.shizuoka.ac.jp; Sanada, Noriaki; Mochizuki, Sachie; Yatsuzuka, Ikuko [Research Institute of Electronics, Shizuoka University, Johoku 3-5-1, Naka-ku, Hamamatsu 432-8011 (Japan)

2013-11-15T23:59:59.000Z

227

Runaway electron energy measurement using hard x-ray spectroscopy in 'Damavand' tokamak  

SciTech Connect

Set of experiments has been developed to study existing runaway electrons in ''Damavand'' tokamak plasma upon characteristics of hard x-ray emissions produced by collision of the runaway electrons with the plasma particles and limiters. As a first step, spatial distribution of hard x-ray emissions on the equatorial plane of the torus was considered. Obtained spectra of hard x-ray emissions for different alignments of shielded detector indicate isotropic emissivity in the equatorial plane. This is in agreement with wide angle cone of bremsstrahlung radiations, deduced from the mean value of energy of the runaway electrons. The mean energy was calculated from the slope of the energy spectrum of hard x-ray photons. In the second stage in order to investigate time evolution of energy of the runaway electrons, similar technique were applied to obtain hard x-ray energy in every 3 ms intervals, from the beginning to the end of plasma. The mean energy of the runaway electrons increases during the ramp up phase and reaches its maximum between 3 and 9 ms after plasma formation. Also considering the time dependence of the counted photons in each energy range shows that energetic photons are emitted during the ramp up phase of the plasma current in Damavand tokamak.

Rasouli, C.; Farahbod, A. H.; Rasouli, H.; Lamehi, M. [School of Plasma Physics and Nuclear Fusion, Institute of Nuclear Science and Technology, AEOI, P.O. Box 14155-1339, Tehran (Iran, Islamic Republic of); Iraji, D. [Centre de Recherches en Physique des Plasmas, Association EURATOM-Confederation Suisse, Ecole Polytechnique Federale de Lausanne, CH-1015 (Switzerland); Akhtari, K. [Department of Physics, Sharif University of Technology, P.O. Box 11365-9161, Tehran (Iran, Islamic Republic of); Modarresi, H. [Department of Mechanical Engineering, Sharif University of Technology, P.O. Box 11365-9567, Tehran (Iran, Islamic Republic of)

2009-01-15T23:59:59.000Z

228

1,3-Alternate calix[4]arene nitronyl nitroxide tetraradical and diradical: synthesis, X-ray crystallography, paramagnetic NMR spectroscopy, EPR spectroscopy, and magnetic studies  

SciTech Connect

Calix[4]arenes constrained to 1,3-alternate conformation and functionalized at the upper rim with four and two nitronyl nitroxides have been synthesized, and characterized by X-ray crystallography, magnetic resonance (EPR and {sup 1}H NMR) spectroscopy, and magnetic studies. Such calix[4]arene tetraradicals and diradicals provide scaffolds for through-bond and through-space intramolecular exchange couplings.

Rajca, Andrzej; Pink, Maren; Mukherjee, Sumit; Rajca, Suchada; Das, Kausik (UNL); (Indiana)

2008-04-02T23:59:59.000Z

229

Phase-resolved optical and X-ray spectroscopy of low-mass X-ray binary X1822-371  

E-Print Network (OSTI)

(Abridged) X1822-371 is the prototypical accretion disc corona X-ray source, a low-mass X-ray binary viewed at very high inclination, thereby allowing the disc structure and extended disc coronal regions to be visible. We study the structure of the accretion disc in X1822-371 by modelling the phase-resolved spectra both in optical and X-ray regime. We analyse high time resolution optical ESO/VLT spectra of X1822-371 to study the variability in the emission line profiles. In addition, we use data from XMM-Newton space observatory to study phase-resolved as well as high resolution X-ray spectra. We apply the Doppler tomography technique to reconstruct a map of the optical emission distribution in the system. We fit multi-component models to the X-ray spectra. We find that our results from both the optical and X-ray analysis can be explained with a model where the accretion disc has a thick rim in the region where the accretion stream impacts the disc. The behaviour of the H_beta line complex implies that some o...

Somero, A; Muhli, P; Charles, P; Vilhu, O

2012-01-01T23:59:59.000Z

230

Transient X-ray pulsar V0332+53: pulse phase-resolved spectroscopy and the reflection model  

E-Print Network (OSTI)

We present the results of the pulse phase- and luminosity-resolved spectroscopy of the transient X-ray pulsar V0332+53, performed for the first time in a wide luminosity range (1-40)x10^{37} erg/s during a giant outburst observed by the RXTE observatory in Dec 2004 - Feb 2005. We characterize the spectra quantitatively and built the detailed "three-dimensional" picture of spectral variations with pulse phase and throughout the outburst. We show that all spectral parameters are strongly variable with the pulse phase, and the pattern of this variability significantly changes with luminosity directly reflecting the associated changes in the structure of emission regions and their beam patterns. Obtained results are qualitatively discussed in terms of the recently developed reflection model for the formation of cyclotron lines in the spectra of X-ray pulsars.

Lutovinov, A A; Suleimanov, V F; Mushtukov, A A; Doroshenko, V; Nagirner, D I; Poutanen, J

2015-01-01T23:59:59.000Z

231

In Situ Ambient Pressure X-ray Photoelectron Spectroscopy Studies of Lithium-Oxygen Redox Reactions  

SciTech Connect

The lack of fundamental understanding of the oxygen reduction and oxygen evolution in nonaqueous electrolytes significantly hinders the development of rechargeable lithium-air batteries. Here we employ a solid-state Li4+xTi5O12/LiPON/LixV2O5 cell and examine in situ the chemistry of Li-O2 reaction products on LixV2O5 as a function of applied voltage under ultra high vacuum (UHV) and near ambient-pressure of oxygen using X-ray photoelectron spectroscopy (APXPS). Oxygen reduction and evolution reactions take place on the surface of the mixed electronic and Li+ ionic conductor, LixV2O5, which eliminate parasitic reactions between oxygen reduction/evolution reaction intermediates and aprotic electrolytes used in Li-O2 batteries reported to date. Under UHV, reversible lithium intercalation and de-intercalation from LixV2O5 was noted, where the changes in the vanadium valence state revealed from XPS in this study were comparable to that reported previously from Li/LixV2O5 thin film batteries. In presence of oxygen near ambient pressure, the LixV2O5 surface was covered gradually by the reaction product of oxygen reduction, namely lithium peroxide (Li2O2) (approximately 1-2 unit cells) upon discharge. Interestingly, the LixV2O5 surface became re-exposed upon charging, and the oxidation of Li2O2 began at much lower overpotentials (~240 mV) than the charge overpotentials of Li-O2 cells (~1000 mV) with aprotic electrolytes, which can be attributed to subnanometer-thick Li2O2 with surfaces free of contaminants such as carbonate species. Our study provides first evidence of reversible lithium peroxide formation and decomposition in situ on an oxide surface using a solid-state cell, and new insights into the reaction mechanism of Li-O2 chemistry.

Lu, Yi-chun [Massachusetts Institute of Technology (MIT); Crumlin, Ethan [Massachusetts Institute of Technology (MIT); Veith, Gabriel M [ORNL; Harding, Jonathon [Massachusetts Institute of Technology (MIT); Dudney, Nancy J [ORNL; Liu, Zhi [Lawrence Berkeley National Laboratory (LBNL); Shao-Horn, Yang [Massachusetts Institute of Technology (MIT)

2012-01-01T23:59:59.000Z

232

The Reactivity and Structural Dynamics of Supported Metal Nanoclusters Using Electron Microscopy, in situ X-Ray Spectroscopy, Electronic Structure Theories, and Molecular Dynamics Simulations.  

SciTech Connect

The distinguishing feature of our collaborative program of study is the focus it brings to emergent phenomena originating from the unique structural/electronic environments found in nanoscale materials. We exploit and develop frontier methods of atomic-scale materials characterization based on electron microscopy (Yang) and synchrotron X-ray absorption spectroscopy (Frenkel) that are in turn coupled innately with advanced first principles theory and methods of computational modeling (Johnson). In the past year we have made significant experimental advances that have led to important new understandings of the structural dynamics of what are unquestionably the most important classes of heterogeneous catalysts—the materials used to both produce and mitigate the consequences of the use of liquid hydrocarbon fuels.

Judith C. Yang; Ralph G. Nuzzo, Duane Johnson, Anatoly Frenkel

2008-07-01T23:59:59.000Z

233

Impact of Ferrocene on the Structure of Diesel Exhaust Soot as Probed with Wide-Angle X-ray Scattering and C(1s) NEXAFS Spectroscopy  

SciTech Connect

We report on the structure of a set of diesel exhaust samples that were obtained from reference diesel fuel and diesel fuel mixed with ferrocene. Characterization was carried out with X-ray absorption spectroscopy (C(1s) NEXAFS) and wide-angle X-ray scattering (WAXS). The reference diesel soot shows a pronounced graphite-like microstructure and molecular structure, with a strong (0 0 2) graphite Bragg reflex and a strong aromatic C{double_bond}C resonance at 285 eV. The mineral matter in the reference soot could be identified as Fe{sub 2}O{sub 3} hematite. The soot specimen from the diesel mixed with ferrocene has an entirely different structure and lacks significantly in graphite-like characteristics. NEXAFS spectra of such soot barely show aromatics but pronounced contributions from aliphatic structures. WAXS patterns show almost no intensity at the Bragg (0 0 2) reflection of graphite, but a strong aliphatic {gamma}-side band. The iron from the ferrocene transforms to Fe{sub 2}O{sub 3} maghemite.

Braun,A.; Huggins, F.; Kelly, K.; Mun, B.; Ehrlich, S.; Huffman, G.

2006-01-01T23:59:59.000Z

234

Closed source experimental system for soft x-ray spectroscopy of radioactive materials  

Science Journals Connector (OSTI)

An instrumental and experimental setup for soft x-rayspectroscopy meeting the requirements of a closed source for radioactivity is described. The system consists of a vacuum sealed cell containing the sample mounted on a tubing system to ensure compatibility with most standard manipulators. The soft x rays penetrate a thin x-ray window separating the interior of the cell from the vacuum in the experimental chamber. Our first results for single crystal PuO 2 confirm the feasibility of experiments using the setup. The results are consistent with results of first principles calculations and previously recorded spectra obtained using a standard open source setup. The results show that the closed source experimental system can be used to collect valuable experimental data from radioactive materials.

A. Modin; S. M. Butorin; J. Vegelius; A. Olsson; C.-J. Englund; J. Andersson; L. Werme; J. Nordgren; T. Käämbre; G. Skarnemark; B. E. Burakov

2008-01-01T23:59:59.000Z

235

Center for X-Ray Optics, 1992  

SciTech Connect

This report discusses the following topics: Center for X-Ray Optics; Soft X-Ray Imaging wit Zone Plate Lenses; Biological X-Ray microscopy; Extreme Ultraviolet Lithography for Nanoelectronic Pattern Transfer; Multilayer Reflective Optics; EUV/Soft X-ray Reflectometer; Photoemission Microscopy with Reflective Optics; Spectroscopy with Soft X-Rays; Hard X-Ray Microprobe; Coronary Angiography; and Atomic Scattering Factors.

Not Available

1993-08-01T23:59:59.000Z

236

Structual Study of Galactic Hot Gas toward Markarian 421 from X-Ray Absorption and Emission Lines  

E-Print Network (OSTI)

We present a structural study of the hot ISM in the Galactic halo along the sight line toward the bright active galactic nucleus Mkn 421. The OVII and OVIII absorption lines were measured with the Low Energy Transmission Grating Spectrograph aboard Chandra toward Mkn 421, and the OVII and OVIII emission lines were observed in the adjacent fields of the sight line with the X-ray Imaging Spectrometer aboard Suzaku. We jointly analyzed the absorption and the emission spectra assuming exponential distributions of the gas temperature and density from the Galactic plane, and constrained the temperature and density at the plane to be $(3.2^{+0.6}_{-0.7})\\times 10^6\\,\\mathrm{K}$ and $(1.2^{+0.5}_{-0.4})\\times 10^{-3}\\,\\mathrm{cm^{-3}}$, with the scale heights of $1.6^{+1.7}_{-0.7}\\,\\mathrm{kpc}$ and $>2.8\\,\\mathrm{kpc}$ respectively. The results are consistent with those obtained in the LMC X-3 direction and the PKS 2155-304 direction, describing a thick disk-like hot gas with its height of a few kpc from the Galacti...

Sakai, Kazuhiro; Mitsuda, Kazuhisa; Yamasaki, Noriko; Wang, Q Daniel; Takei, Yoh; McCammon, Dan

2014-01-01T23:59:59.000Z

237

TiO2 Nanoparticles as a Soft X-ray Molecular Probe  

SciTech Connect

With the emergence of soft x-ray techniques for imaging cells, there is a pressing need to develop protein localization probes that can be unambiguously identified within the region of x-ray spectrum used for imaging. TiO2 nanocrystal colloids, which have a strong absorption cross-section within the "water-window" region of x-rays, areideally suited as soft x-ray microscopy probes. To demonstrate their efficacy, TiO2-streptavidin nanoconjugates were prepared and subsequently labeled microtubules polymerized from biotinylated tubulin. The microtubules were imaged using scanning transmission x-ray microscopy (STXM), and the TiO2 nanoparticle tags were specifically identified using x-ray absorption near edge spectroscopy (XANES). These experiments demonstrate that TiO2 nanoparticles are potential probes for protein localization analyses using soft x-ray microscopy.

Larabell, Carolyn; Ashcroft, Jared M.; Gu, Weiwei; Zhang, Tierui; Hughes, Steven M.; Hartman, Keith B.; Hofmann, Cristina; Kanaras, Antonios G.; Kilcoyne, David A.; Le Gros, Mark; Yin, Yadong; Alivisatos, A. Paul; Larabell, Carolyn A.

2007-06-30T23:59:59.000Z

238

Effect of Residence Time on Ni-Sorption Mechanisms on Clay and Oxide Minerals: An X-ray Absorption Fine Structure (XAFS) Study  

E-Print Network (OSTI)

Effect of Residence Time on Ni-Sorption Mechanisms on Clay and Oxide Minerals: An X-ray Absorption Fine Structure (XAFS) Study A. M. Scheidegger and G. M. Lamble Metal sorption on clay and oxide in reaction rate has been attributed to metal sorption onto sites of lower reactivity, diffusion

Sparks, Donald L.

239

Photo-Induced Spin-State Conversion in Solvated Transition Metal Complexes Probed via Time-Resolved Soft X-ray Spectroscopy  

SciTech Connect

Solution-phase photoinduced low-spin to high-spin conversion in the FeII polypyridyl complex [Fe(tren(py)3)]2+ (where tren(py)3 is tris(2-pyridylmethyliminoethyl)amine) has been studied via picosecond soft X-ray spectroscopy. Following 1A1 --> 1MLCT (metal-to-ligand charge transfer) excitation at 560 nm, changes in the iron L2- and L3-edges were observed concomitant with formation of the transient high-spin 5T2 state. Charge-transfer multiplet calculations coupled with data acquired on low-spin and high-spin model complexes revealed a reduction in ligand field splitting of 1 eV in the high-spin state relative to the singlet ground state. A significant reduction in orbital overlap between the central Fe-3d and the ligand N-2p orbitals was directly observed, consistent with the expected ca. 0.2 Angstrom increase in Fe-N bond length upon formation of the high-spin state. The overall occupancy of the Fe-3d orbitals remains constant upon spin crossover, suggesting that the reduction in sigma-donation is compensated by significant attenuation of pi-back-bonding in the metal-ligand interactions. These results demonstrate the feasibility and unique potential of time-resolved soft X-ray absorption spectroscopy to study ultrafast reactions in the liquid phase by directly probing the valence orbitals of first-row metals as well as lighter elements during the course of photochemical transformations.

Huse, Nils; Kim, Tae Kyu; Jamula, Lindsey; McCusker, James K.; de Groot, Frank M. F.; Schoenlein, Robert W.

2010-04-30T23:59:59.000Z

240

Magnetohydrodynamic modeling of the accretion shocks in classical T Tauri stars: the role of local absorption on the X-ray emission  

E-Print Network (OSTI)

We investigate the properties of X-ray emission from accretion shocks in classical T Tauri stars (CTTSs), generated where the infalling material impacts the stellar surface. Both observations and models of the accretion process reveal several aspects that are still unclear: the observed X-ray luminosity in accretion shocks is below the predicted value, and the density versus temperature structure of the shocked plasma, with increasing densities at higher temperature, deduced from the observations, is at odds with that proposed in the current picture of accretion shocks. To address these open issues we investigate whether a correct treatment of the local absorption by the surrounding medium is crucial to explain the observations. To this end, we describe the impact of an accretion stream on a CTTS by considering a magnetohydrodynamic model. From the model results we synthesize the X-ray emission from the accretion shock by producing maps and spectra. We perform density and temperature diagnostics on the synthe...

Bonito, R; Argiroffi, C; Miceli, M; Peres, G; Matsakos, T; Stehle, C; Ibgui, L

2014-01-01T23:59:59.000Z

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


241

High energy resolution five-crystal spectrometer for high quality fluorescence and absorption measurements on an X-ray Absorption  

E-Print Network (OSTI)

-ray photons from a large solid angle with five spherically bent crystals. It will cover a large energy rangeHigh energy resolution five-crystal spectrometer for high quality fluorescence and absorption however presents some limitations related to the limited energy resolution and saturation. Crystal

Paris-Sud XI, Université de

242

Coronal Evolution of the Sun in Time: High-Resolution X-Ray Spectroscopy of Solar Analogs with Different Ages  

E-Print Network (OSTI)

(abridged) We investigate the long-term evolution of X-ray coronae of solar analogs based on high-resolution X-ray spectroscopy and photometry with XMM-Newton. Six nearby main-sequence G stars with ages between ~0.1 Gyr and \\~1.6 Gyr and rotation periods between ~1d and 12.4d have been observed. We derive coronal element abundances and the coronal emission measure distribution (EMD). The abundances change from an inverse-First Ionization Potential (FIP) distribution in stars with ages around 0.1 Gyr to a solar-type FIP distribution in stars at ages of 0.3 Gyr and beyond. The coronal EMDs show shapes characterized by power-laws on each side of the EMD peak. The latter shifts from temperatures of about 10 MK in the most rapidly rotating, young stars to temperatures around 4 MK in the oldest target considered here. The power-law index on the cooler side of the EMD exceeds expected slopes for static loops, with typical values being 1.5-3. We interpret this slope with a model in which the coronal emission is due to a superposition of stochastically occurring flares, with an occurrence rate that is distributed in radiated energy E as a power-law, dN/dE ~ E^-a. Our EMDs indicate a ~ 2.2-2.8, in excellent agreement with values previously derived from light curves of magnetically active stars. We derive the range of flare energies required to explain the light-curve modulation. In an overall scenario, we propose that flaring activity plays a larger role in more active stars. In this model, the higher flare rate is responsible both for the higher average coronal temperature and the high coronal X-ray luminosity, two parameters that are indeed found to be correlated.

A. Telleschi; M. Guedel; K. Briggs; M. Audard; J. -U. Ness; S. L. Skinner

2005-03-24T23:59:59.000Z

243

PRELIMINARY IN-SITU X-RAY ABSORPTION FINE STRUCTURE EXAMINATION OF PT/C AND PTCO/C CATHODE CATALYSTS IN AN OPERATIONAL POLYMER ELECTROLYTE FUEL CELL  

SciTech Connect

State-of-the-art polymer electrolyte fuel cells require a conditioning period to reach optimized cell performance. There is insuffi cient understanding about the behavior of catalysts during this period, especially with regard to the changing environment of the cathode electrocatalyst, which is typically Pt nanoparticles supported on high surface area Vulcan XC-72 carbon (Pt/C). The purpose of this research was to record preliminary observations of the changing environment during the conditioning phase using X-Ray Absorption Fine Structure (XAFS) spectroscopy. XAFS was recorded for a Pt/C cathode at the Pt L3-edge and a PtCo/C cathode at both the Pt L3-edge and Co K-edge. Using precision machined graphite cell-blocks, both transmission and fl uorescence data were recorded at Sector 12-BM-B of Argonne National Laboratory’s Advanced Photon Source. The fl uorescence and transmission edge steps allow for a working description of the changing electrocatalyst environment, especially water concentration, at the anode and cathode as functions of operating parameters. These features are discussed in the context of how future analysis may correlate with potential, current and changing apparent thickness of the membrane electrode assembly through loss of catalyst materials (anode, cathode, carbon support). Such direct knowledge of the effect of the conditioning protocol on the electrocatalyst may lead to better catalyst design. In turn, this may lead to minimizing, or even eliminating, the conditioning period.

Phelan, B.T.; Myers, D.J.; Smith, M.C.

2009-01-01T23:59:59.000Z

244

X-ray Emission from Massive Stars  

E-Print Network (OSTI)

X-ray Emission from Massive Stars David Cohen Department of Physics and Astronomy Swarthmore #12;What is the mechanism by which massive stars produce x-rays? New results from the Chandra X-ray Observatory ­ high-resolution x-ray spectroscopy: measuring Doppler broadening in emission lines Testing

Cohen, David

245

Optimizing Transition Edge Sensors for High?Resolution X?ray Spectroscopy  

Science Journals Connector (OSTI)

Transition Edge Sensors (TES) have found applications as astronomical detectors ranging from the microwave to the gamma ray energy bands. Each energy band however imposes a different set of requirements on the TES such as energy and timing resolution focal plane coverage and the mechanisms by which the signal is coupled to the detector. This paper focuses on the development of TESs optimized for the 0.1–10 keV energy range at the NASA Goddard Space Flight Center. Such detectors are suitable candidates for some of the upcoming X?ray observatories such as NeXT and Constellation?X. Ongoing efforts at producing characterizing and modeling such devices as well as the latest results are discussed.

Tarek Saab; Simon R. Bandler; Kevin Boyce; James A. Chervenak; Enectali Figueroa?Feliciano; Naoko Iyomoto; Richard L. Kelley; Caroline A. Kilbourne; Frederick S. Porter; John E. Sadleir

2006-01-01T23:59:59.000Z

246

Optimizing Transition Edge Sensors for High-Resolution X-ray Spectroscopy  

SciTech Connect

Transition Edge Sensors (TES) have found applications as astronomical detectors ranging from the microwave to the gamma ray energy bands. Each energy band, however, imposes a different set of requirements on the TES such as energy and timing resolution, focal plane coverage, and the mechanisms by which the signal is coupled to the detector. This paper focuses on the development of TESs optimized for the 0.1-10 keV energy range at the NASA Goddard Space Flight Center. Such detectors are suitable candidates for some of the upcoming X-ray observatories such as NeXT and Constellation-X. Ongoing efforts at producing, characterizing, and modeling such devices, as well as the latest results, are discussed.

Saab, Tarek [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Bandler, Simon R.; Boyce, Kevin; Chervenak, James A.; Figueroa-Feliciano, Enectali; Iyomoto, Naoko; Kelley, Richard L.; Kilbourne, Caroline A.; Porter, Frederick S.; Sadleir, John E

2006-09-07T23:59:59.000Z

247

MOLECULAR ENVIRONMENT AND AN X-RAY SPECTROSCOPY OF SUPERNOVA REMNANT KESTEVEN 78  

SciTech Connect

We investigate the molecular environment of the Galactic supernova remnant (SNR) Kesteven 78 and perform an XMM-Newton X-ray spectroscopic study for the northeastern edge of the remnant. SNR Kes 78 is found to interact with the molecular clouds (MCs) at a systemic local standard of rest velocity of 81 km s{sup -1}. At around this velocity, the SNR appears to contact a long molecular strip in the northeast and a large cloud in the east as revealed in the {sup 13}CO line, which may be responsible for the radio brightness peak and the OH maser, respectively. The {sup 12}CO-line bright region morphologically matches the eastern bright radio shell in general, and the SNR is consistent in extent with a CO cavity. Broadened {sup 12}CO-line profiles discerned in the eastern maser region and the western clumpy molecular arc and the elevated {sup 12}CO (J = 2-1)/(J = 1-0) ratios along the SNR boundary may be signatures of shock perturbation in the molecular gas. The SNR-MC association places the SNR at a kinematic distance of 4.8 kpc. The X-rays arising from the northeastern radio shell are emitted by underionized hot ({approx}1.5 keV), low-density ({approx}0.1 cm{sup -3}) plasma with solar abundance, and the plasma may be of intercloud origin. The age of the remnant is inferred to be about 6 kyr. The size of the molecular cavity in Kes 78 implies an initial mass around 22 M{sub Sun} for the progenitor.

Zhou Ping; Chen Yang [Department of Astronomy, Nanjing University, Nanjing 210093 (China)

2011-12-10T23:59:59.000Z

248

X-Ray Directional Dichroism of a Polar Ferrimagnet  

Science Journals Connector (OSTI)

In a polar ferrimagnet GaFeO3, we have found a novel magneto-optical effect, termed x-ray nonreciprocal directional dichroism (XNDD), that the x-ray absorption at around the K edge of an Fe ion depends on whether the x-ray propagation vector is parallel or antiparallel to the outer product of the magnetization and electric-polarization vectors. The XNDD spectroscopy as demonstrated here can be a useful tool to probe the local magnetism in noncentrosymmetric systems such as magnetic interfaces and nanostructures.

M. Kubota, T. Arima, Y. Kaneko, J. P. He, X. Z. Yu, and Y. Tokura

2004-03-29T23:59:59.000Z

249

MOLECULAR ENVIRONMENT AND THERMAL X-RAY SPECTROSCOPY OF THE SEMICIRCULAR YOUNG COMPOSITE SUPERNOVA REMNANT 3C 396  

SciTech Connect

We have investigated the molecular environment of the semicircular composite supernova remnant (SNR) 3C 396 and performed a Chandra spatially resolved thermal X-ray spectroscopic study of this young SNR. With our CO millimeter observations, we find that the molecular clouds (MCs) at V{sub LSR}{approx} 84 km s{sup -1} can better explain the multiwavelength properties of the remnant than the V{sub LSR} = 67-72 km s{sup -1} MCs that are suggested by Lee et al. At around 84 km s{sup -1}, the western boundary of the SNR is perfectly confined by the western molecular wall. The CO emission fades out from west to east, indicating that the eastern region is of low gas density. In particular, an intruding finger/pillar-like MC, which may be shocked at the tip, can well explain the X-ray and radio enhancement in the southwest and some infrared filaments there. The SNR-MC interaction is also favored by the relatively elevated {sup 12}CO J = 2-1/J = 1-0 line ratios in the southwestern 'pillar tip' and the molecular patch on the northwestern boundary. The redshifted {sup 12}CO (J = 1-0 and J = 2-1) wings (86-90 km s{sup -1}) of an eastern 81 km s{sup -1} molecular patch may be the kinematic evidence for shock-MC interaction. We suggest that the 69 km s{sup -1} MCs are in the foreground based on H I self-absorption while the 84 km s{sup -1} MCs at a distance of 6.2 kpc (the tangent point) are in physical contact with SNR 3C 396. The X-ray spectral analysis suggests an SNR age of {approx}3 kyr. The metal enrichment of the X-ray emitting gas in the north and south implies a 13-15 M{sub sun} B1-B2 progenitor star.

Su Yang; Yang Ji; Lu Dengrong [Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing 210008 (China); Yang Chen; Zhou Xin [Department of Astronomy, Nanjing University, Nanjing 210093 (China); Koo, Bon-Chul; Jeong, Il-Gyo [Astronomy Program, Department of Physics and Astronomy, Seoul National University, Seoul 151-747 (Korea, Republic of); DeLaney, Tracey [Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, 70 Vassar Street, Cambridge, MA 02139 (United States)

2011-01-20T23:59:59.000Z

250

X-RAYS FROM A RADIO-LOUD COMPACT BROAD ABSORPTION LINE QUASAR 1045+352 AND THE NATURE OF OUTFLOWS IN RADIO-LOUD BROAD ABSORPTION LINE QUASARS  

SciTech Connect

We present new results on X-ray properties of radio-loud broad absorption line (BAL) quasars and focus on broadband spectral properties of a high-ionization BAL (HiBAL) compact steep spectrum (CSS) radio-loud quasar 1045+352. This HiBAL quasar has a very complex radio morphology indicating either strong interactions between a radio jet and the surrounding interstellar medium or a possible re-start of the jet activity. We detected 1045+352 quasar in a short 5 ksec Chandra ACIS-S observation. We applied theoretical models to explain spectral energy distribution of 1045+352 and argue that non-thermal, inverse-Compton (IC) emission from the innermost parts of the radio jet can account for a large fraction of the observed X-ray emission. In our analysis, we also consider a scenario in which the observed X-ray emission from radio-loud BAL quasars can be a sum of IC jet X-ray emission and optically thin corona X-ray emission. We compiled a sample of radio-loud BAL quasars that were observed in X-rays to date and report no correlation between their X-ray and radio luminosity. However, the radio-loud BAL quasars show a large range of X-ray luminosities and absorption columns. This is consistent with the results obtained earlier for radio-quiet BAL quasars and may indicate an orientation effect in BAL quasars or more complex dependence between X-ray emission, radio emission, and an orientation based on the radio morphology.

Kunert-Bajraszewska, Magdalena; Katarzynski, Krzysztof [Torun Centre for Astronomy, N. Copernicus University, Gagarina 11, 87-100 Torun (Poland); Siemiginowska, Aneta [Harvard Smithsonian Center for Astrophysics, 60 Garden St., Cambridge, MA 02138 (United States); Janiuk, Agnieszka [N. Copernicus Astronomical Center, Bartycka 18, 00-716 Warsaw (Poland)

2009-11-10T23:59:59.000Z

251

Electronic structure of Al- and Ga-doped ZnO films studied by hard X-ray photoelectron spectroscopy  

SciTech Connect

Al- and Ga-doped sputtered ZnO films (AZO, GZO) are semiconducting and metallic, respectively, despite the same electronic valence structure of the dopants. Using hard X-ray photoelectron spectroscopy we observe that both dopants induce a band in the electronic structure near the Fermi level, accompanied by a narrowing of the Zn 3d/O 2p gap in the valence band and, in the case of GZO, a substantial shift in the Zn 3d. Ga occupies substitutional sites, whereas Al dopants are in both substitutional and interstitial sites. The latter could induce O and Zn defects, which act as acceptors explaining the semiconducting character of AZO and the lack of variation in the optical gap. By contrast, mainly substitutional doping is consistent with the metallic-like behavior of GZO.

Gabás, M.; Ramos Barrado, José R. [Lab. de Materiales and Superficies, Dpto. de Física Aplicada I, Universidad de Málaga, 29071 Málaga (Spain); Torelli, P. [Laboratorio TASC, IOM-CNR, S.S. 14 km 163.5, Basovizza, I-34149 Trieste (Italy); Barrett, N. T. [CEA, DSM/IRAMIS/SPCSI, F-91191 Gif-sur-Yvette Cedex (France); Sacchi, M. [Synchrotron SOLEIL, BP 48, 91192 Gif-sur-Yvette, France and Institut des NanoSciences de Paris, UPMC Paris 06, CNRS UMR 7588, 4 Place Jussieu, 75005 Paris (France)

2014-01-01T23:59:59.000Z

252

X-ray spectroscopy study of electronic structure of laser-irradiated Au nanoparticles in a silica film  

SciTech Connect

The electronic structure of gold nanoparticles embedded in a silica film is studied, both before and after irradiation at 355 nm by a laser. The Au 5d occupied valence states are observed by x-ray emission spectroscopy. They show that before irradiation the gold atoms are in metallic states within the nanoparticles. After irradiation with a fluence of 0.5 J/cm{sup 2}, it is found that gold valence states are close to those of a metal-poor gold silicide; thanks to a comparison of the experimental Au 5d states with the calculated ones for gold silicides using the density-functional theory. The formation of such a compound is driven by the diffusion of the gold atoms into the silica film upon the laser irradiation. At higher fluence, 1 J/cm{sup 2}, we find a higher percentage of metallic gold that could be attributed to annealing in the silica matrix.

Jonnard, P.; Bercegol, H.; Lamaignere, L.; Morreeuw, J.-P.; Rullier, J.-L.; Cottancin, E.; Pellarin, M. [Laboratoire de Chimie Physique-Matiere et Rayonnement, Universite Pierre et Marie Curie, Centre National de la Recherche Scientifique Unite Mixte de Recherche (CNRS UMR) 7614, 11 rue Pierre et Marie Curie, F-75231 Paris Cedex 05 (France); Commissariat a l'Energie Atomique/Centre d'Etudes Scientifiques et Techniques d'Aquitaine (CEA/CESTA), BP 2, F-33114, Le Barp (France); Centre Agregat Laboratoire de Spectrometrie Ionique et Moleculaire (LASIM) et Laboratoire de Physique de la Matiere Condensee et Nanostructures (LPMCN), Universite Claude Bernard Lyon I, F-69622 Villeurbanne (France)

2005-03-15T23:59:59.000Z

253

X-ray photoelectron spectroscopy study of para-substituted benzoic acids chemisorbed to aluminum oxide thin films  

SciTech Connect

A series of para-substituted, halogenated (F, Cl, Br, and I) benzoic acid monolayers were prepared on the native oxide of aluminum surfaces by solution self-assembly and spin-coating techniques. The monolayers were characterized by x-ray photoelectron spectroscopy (XPS) and water contact angles. Several general trends are apparent. First, the polarity of the solvent is critical to monolayer formation. Protic polar solvents produced low coverage monolayers; in contrast, nonpolar solvents produced higher coverage monolayers. Second, solution deposition yields a higher surface coverage than spin coating. Third, the thickness of the monolayers determined from XPS suggests the plane of the aromatic ring is perpendicular to the surface with the carboxylate functional group most likely binding in a bidentate chelating geometry. Fourth, the saturation coverage (?2.7 × 10{sup 14} molecules cm{sup ?2}) is independent of the para-substituent.

Kreil, Justin; Ellingsworth, Edward; Szulczewski, Greg [Department of Chemistry, The University of Alabama, Shelby Hall, 250 Hackberry Lane, Tuscaloosa, Alabama 35487 (United States)] [Department of Chemistry, The University of Alabama, Shelby Hall, 250 Hackberry Lane, Tuscaloosa, Alabama 35487 (United States)

2013-11-15T23:59:59.000Z

254

Phosphorus determination in borophosphosilicate or phosphosilicate glass films on a Si wafer by wavelength dispersive x-ray spectroscopy  

SciTech Connect

In this report, peak shift effects in the SiO{sub 2}/Si(100) system due to chemical bonding are demonstrated. The detailed development of the equations appears in a paper submitted for publication in the Journal of X-ray Spectroscopy. These equations are for the spectral line intensity of Si and P from BPSG films and from the Si in the Si(100) substrate. They are subsequently integrated into two simultaneous equations that can be solved for the phosphorus content and the surface density by a computer program using iterative methods. The general expressions for the BPSG films and the computer program are also applicable to PSG films by setting the boron content to zero. The new procedure was then tested by analysis of a well-defined and carefully prepared set of PSG wafer samples. Preliminary analyses were also made on BPSG wafers. 3 refs., 4 figs., 3 tabs.

Levine, H.S.; Higgins, K.L.

1990-01-01T23:59:59.000Z

255

Combining Feedback Absorption Spectroscopy, Amplified Resonance...  

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

On-Board Measurement of Ammonia and Nitrous Oxide Using Feedback Absorption Laser Spectroscopy Combined with Amplified Resonance and Low Pressure Sampling Cummins...

256

High-resolution x-ray spectroscopy with the EBIT Calorimeter Spectrometer  

SciTech Connect

The EBIT Calorimeter Spectrometer (ECS) is a production-class 36 pixel x-ray calorimeter spectrometer that has been continuously operating at the Electron Beam Ion Trap (EBIT) facility at Lawrence Livermore National Laboratory for almost 2 years. The ECS was designed to be a long-lifetime, turn-key spectrometer that couples high performance with ease of operation and minimal operator intervention. To this end, a variant of the Suzaku/XRS spaceflight detector system has been coupled to a low-maintenance cryogenic system consisting of a long-lifetime liquid He cryostat, and a closed cycle, {sup 3}He pre-cooled adiabatic demagnetization refrigerator. The ECS operates for almost 3 weeks between cryogenic servicing and the ADR operates at 0.05 K for more than 60 hours between automatic recycles under software control. Half of the ECS semiconductor detector array is populated with mid-band pixels that have a resolution of 4.5 eV FWHM, a bandpass from 0.05-12 keV, and a quantum efficiency of 95% at 6 keV. The other half of the array has thick HgTe absorbers that have a bandpass from 0.3 to over 100 keV, an energy resolution of 33 eV FWHM, and a quantum efficiency of 32% at 60 keV. In addition, the ECS uses a real-time, autonomous, data collection and analysis system developed for the Suzaku/XRS instrument and implemented in off-the-shelf hardware for the ECS. Here we will discuss the performance of the ECS instrument and its implementation as a turnkey cryogenic detector system.

Porter, F. Scott; Adams, Joseph S.; Kelley, Richard L.; Kilbourne, Caroline A. [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Beiersdorfer, Peter; Brown, Gregory V.; Clementson, Joel; Frankel, Miriam [Lawrence Livermore National Laboratory, Livermore, CA 94550 (United States); Kahn, Steven M. [Stanford University, Stanford, CA 94305 (United States)

2009-12-16T23:59:59.000Z

257

High-resolution x-ray spectroscopy with the EBIT Calorimeter Spectrometer  

SciTech Connect

The EBIT Calorimeter Spectrometer (ECS) is a production-class 36 pixel x-ray calorimeter spectrometer that has been continuously operating at the Electron Beam Ion Trap (EBIT) facility at Lawrence Livermore National Laboratory for almost 2 years. The ECS was designed to be a long-lifetime, turn-key spectrometer that couples high performance with ease of operation and minimal operator intervention. To this end, a variant of the Suzaku/XRS spaceflight detector system has been coupled to a low-maintenance cryogenic system consisting of a long-lifetime liquid He cryostat, and a closed cycle, {sup 3}He pre-cooled adiabatic demagnetization refrigerator. The ECS operates for almost 3 weeks between cryogenic servicing and the ADR operates at 0.05 K for more than 60 hours between automatic recycles under software control. Half of the ECS semiconductor detector array is populated with mid-band pixels that have a resolution of 4.5 eV FWHM, a bandpass from 0.05-12 keV, and a quantum efficiency of 95% at 6 keV. The other half of the array has thick HgTe absorbers that have a bandpass from 0.3 to over 100 keV, an energy resolution of 33 eV FWHM, and a quantum efficiency of 32% at 60 keV. In addition, the ECS uses a real-time, autonomous, data collection and analysis system developed for the Suzaku/XRS instrument and implemented in off-the-shelf hardware for the ECS. Here we will discuss the performance of the ECS instrument and its implementation as a turnkey cryogenic detector system.

Porter, F S; Adams, J S; Beiersdorfer, P; Brown, G V; Clementson, J; Frankel, M; Kahn, S M; Kelley, R L; Kilbourne, C A

2009-10-01T23:59:59.000Z

258

X-ray absorption studies of the local structure and f-level occupancy in CeIr(1-x)Rh(x)In(5)  

SciTech Connect

The CeIr{sub 1-x}Rh{sub x}In{sub 5} series exhibits a range of interesting phenomena, including heavy-fermion superconductivity, non-Fermi liquid behavior, and concomitant antiferromagnetism (AF) and superconductivity (SC). In the low-Rh concentration range (0.1 {ge} x {ge} 0.5), specific heat measurements show a broad anomaly, suggestive of gross phase separation. We have performed x-ray absorption experiments at the Ce L{sub III}, Ir L{sub III}, and Rh K-edges as a function of Rh concentration and temperature. X-ray absorption near-edge structure (XANES) measurements indicate that cerium is close to trivalent in this system, with no measurable change with temperature from 20-300 K, consistent with a heavy-fermion material. Extended x-ray absorption fine structure (EXAFS) measurements as a function of temperature from all measured edges indicate the local crystal structure of all samples is well ordered, with no gross phase separation observed, even for samples with x = 0.125 and x = 0.25. These results therefore suggest that the anomalous specific heat behavior in the 0.1 {ge} x {ge} 0.5 range have some other explanation, and some possibilities are discussed.

Daniel, M.; Han, S.-W.; Booth, C.H.; Cornelius, A.L.; Pagliuso, P.G.; Sarrao, J.L.; Thompson, J.D.

2004-04-15T23:59:59.000Z

259

RHESSI HARD X-RAY IMAGING SPECTROSCOPY OF EXTENDED SOURCES AND THE PHYSICAL PROPERTIES OF ELECTRON ACCELERATION REGIONS IN SOLAR FLARES  

E-Print Network (OSTI)

RHESSI HARD X-RAY IMAGING SPECTROSCOPY OF EXTENDED SOURCES AND THE PHYSICAL PROPERTIES OF ELECTRON of the acceleration region but also allows an empirical study of the physics of electron tran- sport within the source acceleration and propagation of bremsstrahlung- producing electrons in solar flares. The method involves

California at Berkeley, University of

260

Near-Edge X-ray Absorption Fine Structure Imaging of Spherical and Flat Counterfaces of Ultrananocrystalline Diamond Tribological Contacts: A Correlation of Surface Chemistry and Friction  

SciTech Connect

A recently installed synchrotron radiation near-edge X-ray absorption fine structure (NEXAFS) full field imaging electron spectrometer was used to spatially resolve the chemical changes of both counterfaces from an ultra-nanocrystalline diamond (UNCD) tribological contact. A silicon flat and Si{sub 3}N{sub 4} sphere were both coated with UNCD, and employed to form two wear tracks on the flat in a linear reciprocating tribometer. The first wear track was produced using a new, unconditioned sphere whose surface was thus conditioned during this first experiment. This led to faster run-in and lower friction when producing a second wear track using the conditioned sphere. The large depth of field of the magnetically guided NEXAFS imaging detector enabled rapid, large area spectromicroscopic imaging of both the spherical and flat surfaces. Laterally resolved NEXAFS data from the tribological contact area revealed that both substrates had an as-grown surface layer that contained a higher fraction of sp{sup 2}-bonded carbon and oxygen which was mechanically removed. Unlike the flat, the film on the sphere showed evidence of having graphitic character, both before and after sliding. These results show that the graphitic character of the sphere is not solely responsible for low friction and short run-in. Rather, conditioning the sphere, likely by removing asperities and passivating dangling bonds, leads to lower friction with less chemical modification of the substrate in subsequent tests. The new NEXAFS imaging spectroscopy detector enabled a more complete understanding of the tribological phenomena by imaging, for the first time, the surface chemistry of the spherical counterface which had been in continual contact during wear track formation.

A Konicek; C Jaye; M Hamilton; W Sawyer; D Fischer; R Carpick

2011-12-31T23:59:59.000Z

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


261

Coronal Evolution of the Sun in Time: High-Resolution X-Ray Spectroscopy of Solar Analogs with Different Ages  

Science Journals Connector (OSTI)

We investigate the long-term evolution of X-ray coronae of solar analogs based on high-resolution X-ray spectroscopy and photometry with XMM-Newton. Six nearby main-sequence G stars with ages between ?0.1 and ?1.6 Gyr and rotation periods between ?1 and 12.4 days have been observed. We use the X-ray spectra to derive coronal element abundances of C, N, O, Ne, Mg, Si, S, and Fe and the coronal emission measure distribution (EMD). We find that the abundances change from an inverse first ionization potential (FIP) distribution in stars with ages around 0.1 Gyr to a solar-type FIP distribution in stars at ages of 0.3 Gyr and beyond. This transformation is coincident with a steep decline of nonthermal radio emission. The results are in qualitative agreement with a simple model in which the stream of electrons in magnetic fields suppresses diffusion of low-FIP ions from the chromosphere into the corona. The coronal emission measure distributions show shapes characterized by power laws on each side of the EMD peak. The latter shifts from temperatures of about 10 MK in the most rapidly rotating, young stars to temperatures around 4 MK in the oldest target considered here. The power-law index on the cooler side of the EMD exceeds expected slopes for static loops, with typical values being 1.5-3. We interpret this slope with a model in which the coronal emission is due to a superposition of stochastically occurring flares, with an occurrence rate that is distributed in radiated energy E as a power law, dN/dE ? E-?, as previously found for solar and stellar flares. We obtain the relevant power-law index ? from the slope of the high-temperature tail of the EMD. Our EMDs indicate ? ? 2.2-2.8, in excellent agreement with values previously derived from light curves of magnetically active stars. Modulation with timescales reminiscent of flares is found in the light curves of all our targets. Several strong flares are also observed. We use our ?-values to simulate light curves and compare them with the observed light curves. We thus derive the range of flare energies required to explain the light-curve modulation. More active stars require a larger range of flare energies than less active stars within the framework of this simplistic model. In an overall scenario, we propose that flaring activity plays a larger role in more active stars. In this model, the higher flare rate is responsible both for the higher average coronal temperature and the high coronal X-ray luminosity, two parameters that are indeed found to be correlated.

Alessandra Telleschi; Manuel Güdel; Kevin Briggs; Marc Audard; Jan-Uwe Ness; Stephen L. Skinner

2005-01-01T23:59:59.000Z

262

Nuclear quantum effects in the structure and lineshapes of the N{sub 2} near-edge x-ray absorption fine structure spectrum  

SciTech Connect

We study the relative ability of several models of x-ray absorption spectra to capture the Franck-Condon structure apparent from an experiment on gaseous nitrogen. In doing so, we adopt the Born-Oppenheimer approximation and a constrained density functional theory method for computing the energies of the x-ray-excited molecule. Starting from an otherwise classical model for the spectrum, we systematically introduce more realistic physics, first by substituting the quantum mechanical nuclear radial density in the bond separation R for the classical radial density, then by adding the effect of zero-point energy and other level shifts, and finally by including explicit rovibrational quantization of both the ground and excited states. The quantization is determined exactly, using a discrete variable representation (DVR). We show that the near-edge x-ray absorption fine structure (NEXAFS) spectrum can be predicted semiquantitatively within this framework. We also address the possibility of non-trivial temperature dependence in the spectrum. By using constrained density functional theory in combination with more accurate potentials, we demonstrate that it is possible to improve the predicted spectrum. Ultimately, we establish the predictive limits of our method with respect to vibrational fine structure in NEXAFS spectra.

Fatehi, Shervin; Schwartz, Craig P.; Saykally, Richard J. [Department of Chemistry, University of California, Berkeley, California 94720 (United States) and Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Prendergast, David [Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)

2010-03-07T23:59:59.000Z

263

X-ray Absorption Measurements on Nickel Cathode of Sodium-beta Alumina batteries: Fe-Ni-CI Chemical Associations  

SciTech Connect

Sections of Na-Al-NiCl2 cathodes from sodium-beta alumina ZEBRA batteries have been characterized with X-ray fluorescence mapping, and XANES measurements to probe the microstructure, elemental correlation, and chemical speciation after voltage cycling. Cycling was performed under identical load conditions at either 240 or 280 °C operating temperature and subsequently quenched in either the charged or discharged state. X-ray fluorescence mapping and XANES measurements were made adjacent to the current collector and ?"-Al2O3 solid electrolyte interfaces to detect possible gradients in chemical properties across the cathode. An FeS additive, introduced during battery synthesis, was found to be present as either Fe metal or an Fe(II) chloride in all cathode samples. X-ray fluorescence mapping reveals an operating temperature and charge-state dependent spatial correlation between Fe, Ni, and Cl concentration. XANES measurements indicate that both Ni and Fe are chemically reactive and shift between metallic and chloride phases in the charged and discharged states, respectively. However the percentage of chemically active Ni and Fe is significantly less in the cell operated at lower temperature. Additionally, the cathode appeared chemically homogeneous at the scale of our X-ray measurements.

Bowden, Mark E.; Alvine, Kyle J.; Fulton, John L.; Lemmon, John P.; Lu, Xiaochuan; Webb-Robertson, Bobbie-Jo M.; Heald, Steve M.; Balasubramanian, Mahalingam; Mortensen, Devon R.; Seidler, Gerald T.; Hess, Nancy J.

2014-02-01T23:59:59.000Z

264

In-situ X-ray photoelectron spectroscopy studies of water on metals and oxides at ambient conditions  

SciTech Connect

X-ray photoelectron spectroscopy (XPS) is a powerful tool for surface and interface analysis, providing the elemental composition of surfaces and the local chemical environment of adsorbed species. Conventional XPS experiments have been limited to ultrahigh vacuum (UHV) conditions due to a short mean free path of electrons in a gas phase. The recent advances in instrumentation coupled with third-generation synchrotron radiation sources enables in-situ XPS measurements at pressures above 5 Torr. In this review, we describe the basic design of the ambient pressure XPS setup that combines differential pumping with an electrostatic focusing. We present examples of the application of in-situ XPS to studies of water adsorption on the surface of metals and oxides including Cu(110), Cu(111), TiO2(110) under environmental conditions of water vapor pressure. On all these surfaces we observe a general trend where hydroxyl groups form first, followed by molecular water adsorption. The importance of surface OH groups and their hydrogen bonding to water molecules in water adsorption on surfaces is discussed in detail.

Salmeron, Miquel; Yamamoto, S.; Bluhm, H.; Andersson, K.; Ketteler, G.; Ogasawara, H.; Salmeron, M.; Nilsson, A.

2007-10-29T23:59:59.000Z

265

In situ x-ray photoelectron spectroscopy studies of gas/solidinterfaces at near-ambient conditions  

SciTech Connect

X-ray photoelectron spectroscopy (XPS) is a quantitative, chemically specific technique with a probing depth of a few angstroms to a few nanometers. It is therefore ideally suited to investigate the chemical nature of the surfaces of catalysts. Because of the scattering of electrons by gas molecules, XPS is generally performed under vacuum conditions. However, for thermodynamic and/or kinetic reasons, the catalyst's chemical state observed under vacuum reaction conditions is not necessarily the same as that of a catalyst under realistic operating pressures. Therefore, investigations of catalysts should ideally be performed under reaction conditions, i.e., in the presence of a gas or gas mixtures. Using differentially pumped chambers separated by small apertures, XPS can operate at pressures of up to 1 Torr, and with a recently developed differentially pumped lens system, the pressure limit has been raised to about 10 Torr. Here, we describe the technical aspects of high-pressure XPS and discuss recent applications of this technique to oxidation and heterogeneous catalytic reactions on metal surfaces.

Bluhm, Hendrik; Havecker, Michael; Knop-Gericke, Axel; Kiskinova,Maya; Schlogl, Robert; Salmeron, Miquel

2007-12-03T23:59:59.000Z

266

Revealing the Dual Nature of Magnetism in Iron Pnictides and Iron Chalcogenides Using X-ray Emission Spectroscopy  

SciTech Connect

We report a Fe K{beta} x-ray emission spectroscopy study of local magnetic moments in various iron-based superconductors in their paramagnetic phases. Local magnetic moments are found in all samples studied: PrFeAsO, Ba(Fe,Co){sub 2}As{sub 2}, LiFeAs, Fe{sub 1+x}(Te,Se), and A{sub 2}Fe{sub 4}Se{sub 5} (where A = K, Rb, and Cs). The moment size is independent of temperature or carrier concentration but varies significantly across different families. Specifically, all iron pnictide samples have local moments of about 1 {micro}B/Fe, while FeTe and K{sub 2}Fe{sub 4}Se{sub 5} families have much larger local moments of {approx}2 {micro}B/Fe and {approx}3.3 {micro}B/Fe, respectively. Our results illustrate the importance of multiorbital physics in describing magnetism of these compounds.

Gretarsson H.; Xu Z.; Lupascu, A.; Kim, J.; Casa, D.; Gog, T,; Wu, W.; Julian, S.R.; Wen, J.S.; Gu, G.D.; Yuan, R.H.; Chen, Z.G.; Wang, N.-L.; Khim, S.; Kim, K.H.; Ishikado, M.; Jarrige, I.; Shamoto, S.; Chu, J.-H.; Fisher, I.R.and Young-June Kim

2011-09-22T23:59:59.000Z

267

X-Ray Physics Evan Berkowitz  

E-Print Network (OSTI)

X-Ray Physics Evan Berkowitz Junior, MIT Department of Physics (Dated: October 25, 2006) We measure a variety of phenomena related to X-Ray absorption and production. We present data which conforms within, as are 22 Na electron-positron annhilation lines. The importance of understanding x-rays is demonstrated

268

Self-corrected Sensors Based On Atomic Absorption Spectroscopy...  

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

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

269

X-ray fluorescence microscopy allows geochemists to map the distributions of many different elements simultaneously in  

E-Print Network (OSTI)

molecular and atomic orbitals. Clorg compounds display discrete absorption maxima corresponding to 1s-ray absorption spectroscopy is highly sensitive to the bonding state of Cl, allowing distinctions to be drawn procedures. The dramatic increase in X-ray absorption around 2,822 eV (Cl K-absorption edge

Duffy, Thomas S.

270

Resonant soft X-ray emission spectroscopy of vanadium oxides andrelated compounds  

SciTech Connect

In today's information world, bits of data are processed by semiconductor chips, and stored in the magnetic disk drives. But tomorrow's information technology may see magnetism (spin) and semiconductivity (charge) combined in one ''spintronic'' device that exploits both charge and ''spin'' to carry data (the best of two worlds). Spintronic devices such as spin valve transistors, spin light emitting diodes, non-volatile memory, logic devices, optical isolators and ultra-fast optical switches are some of the areas of interest for introducing the ferromagnetic properties at room temperature in a semiconductor to make it multifunctional. The potential advantages of such spintronic devices will be higher speed, greater efficiency, and better stability at a reduced power consumption. This Thesis contains two main topics: In-depth understanding of magnetism in Mn doped ZnO, and our search and identification of at least six new above room temperature ferromagnetic semiconductors. Both complex doped ZnO based new materials, as well as a number of nonoxides like phosphides, and sulfides suitably doped with Mn or Cu are shown to give rise to ferromagnetism above room temperature. Some of the highlights of this work are discovery of room temperature ferromagnetism in: (1) ZnO:Mn (paper in Nature Materials, Oct issue, 2003); (2) ZnO doped with Cu (containing no magnetic elements in it); (3) GaP doped with Cu (again containing no magnetic elements in it); (4) Enhancement of Magnetization by Cu co-doping in ZnO:Mn; and (5) CdS doped with Mn, and a few others not reported in this thesis. We discuss in detail the first observation of ferromagnetism above room temperature in the form of powder, bulk pellets, in 2-3 {micro}m thick transparent pulsed laser deposited films of the Mn (< 4 at.%) doped ZnO. High-resolution transmission electron microscopy (HRTEM) and electron energy loss spectroscopy (EELS) spectra recorded from 2 to 200nm areas showed homogeneous distribution of Mn substituting for Zn a 2{sup +} state in the ZnO lattice. Ferromagnetic Resonance (FMR) technique is used to confirm the existence of ferromagnetic ordering at temperatures as high as 425K. The ab initio calculations were found to be consistent with the observation of ferromagnetism arising from fully polarized Mn 2{sup +} state. The key to observed room temperature ferromagnetism in this system is the low temperature processing, which prevents formation of clusters, secondary phases and the host ZnO from becoming n-type. The electronic structure of the same Mn doped ZnO thin films studied using XAS, XES and RIXS. revealed a strong hybridization between Mn 3d and O 2p states, which is an important characteristic of a Dilute magnetic Semiconductor (DMS). It is shown that the various processing conditions like sintering temperature, dopant concentration and the properties of precursors used for making of DMS have a great influence on the final properties. Use of various experimental techniques to verify the physical properties, and to understand the mechanism involved to give rise to ferromagnetism is presented. Methods to improve the magnetic moment in Mn doped ZnO are also described. New promising DMS materials (such as Cu doped ZnO are explored). The demonstrated new capability to fabricate powder, pellets, and thin films of room temperature ferromagnetic semiconductors thus makes possible the realization of a wide range of complex elements for a variety of new multifunctional phenomena related to Spintronic devices as well as magneto-optic components.

Schmitt, Thorsten

2004-11-01T23:59:59.000Z

271

In situ x-ray absorption study of Zr(V0.29Ni0.71)3 hydride electrodes  

Science Journals Connector (OSTI)

We present an in situ x-ray absorption study of hydrogen absorption into the bulk of an electrode material while it is operating in an electrochemical cell. The active material is an overstoichiometric AB2-type alloy, namely, Zr(V0.29Ni0.71)3, with a cubic C15 Laves phase structure. Hydrogen absorption induces both structural and electronic changes due to the bonding between interstitial H atoms and each alloy element. The role of each element is revealed, allowing us to determine the inert role of Ni atoms and the dominant effect of the H-V interaction on the hydride formation process. Comparison between the alloyed element behavior and the H affinity of each pure element allows us to determine the influence of structural and alloying effects on bonding formation.

R. G. Agostino; G. Liberti; V. Formoso; E. Colavita; A. Züttel; C. Nützenadel; L. Schlapbach; A. Santaniello; C. Gauthier

2000-05-15T23:59:59.000Z

272

Absorption spectroscopy of a laboratory photoionized plasma experiment at Z  

SciTech Connect

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.

Hall, I. M.; Durmaz, T.; Mancini, R. C. [Physics Department, University of Nevada, Reno, Nevada 89557 (United States)] [Physics Department, University of Nevada, Reno, Nevada 89557 (United States); Bailey, J. E.; Rochau, G. A. [Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States)] [Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States); Golovkin, I. E.; MacFarlane, J. J. [Prism Computational Sciences, Madison, Wisconsin 53711 (United States)] [Prism Computational Sciences, Madison, Wisconsin 53711 (United States)

2014-03-15T23:59:59.000Z

273

Influence of the multiple scattering of relativistic electrons on the line width of backward Parametric X-ray Radiation in the absence of photo absorption  

E-Print Network (OSTI)

The multiple scattering effect on the line width of backward Parametric X-ray Radiation (PXR) in the extremely Bragg geometry, produced by low energy relativistic electrons traversing a single crystal, is discussed. It is shown that there exist conditions, when the influence of photo absorption on the line width can be neglected, and the only multiple scattering process of relativistic electrons in crystal leads to the broadening of backward PXR lines. Based on the obtained theoretical results, the line width broadening of backward PXR, caused by the multiple scattering of 30 MeV and 50 MeV relativistic electrons in a Si crystal of varying thicknesses, is numerically obtained.

Tabrizi, Mehdi

2015-01-01T23:59:59.000Z

274

Vibrational Spectroscopy and X-ray Diffraction of Cd(OH)2 to 28 GPa at 300 K  

E-Print Network (OSTI)

structure parameters of the brucite-type hydroxides. Thederivative (K 0 ) of the brucite-type hydroxides. Materialwith X-ray di?raction for brucite- type ?-Cd(OH) 2 to 28 GPa

Shim, Sang-Heon; Rekhi, Sandeep; Martin, Michael C.; Jeanloz, Raymond

2006-01-01T23:59:59.000Z

275

Fabrication of high-throughput critical-angle X-ray transmission gratings for wavelength-dispersive spectroscopy  

E-Print Network (OSTI)

The development of the critical-angle transmission (CAT) grating seeks both an order of magnitude improvement in the effective area, and a factor of three increase in the resolving power of future space-based, soft x-ray ...

Bruccoleri, Alexander Robert

2013-01-01T23:59:59.000Z

276

End station for nanoscale magnetic materials study: Combination of scanning tunneling microscopy and soft X-ray magnetic circular dichroism spectroscopy  

SciTech Connect

We have constructed an end station for nanoscale magnetic materials study at the soft X-ray beamline HiSOR BL-14 at Hiroshima Synchrotron Radiation Center. An ultrahigh-vacuum scanning tunneling microscope (STM) was installed for an in situ characterization of nanoscale magnetic materials in combination with soft X-ray magnetic circular dichroism (XMCD) spectroscopy experiment. The STM was connected to the XMCD experimental station via damper bellows to isolate it from environmental vibrations, thus achieving efficient spatial resolution for observing Si(111) surface at atomic resolution. We performed an in situ experiment with STM and XMCD spectroscopy on Co nanoclusters on an Au(111) surface and explored its practical application to investigate magnetic properties for well-characterized nanoscale magnetic materials.

Ueno, Tetsuro; Sawada, Masahiro; Namatame, Hirofumi [Hiroshima Synchrotron Radiation Center, Hiroshima University, 2-313 Kagamiyama, Higashi-Hiroshima 739-0046 (Japan); Kishimizu, Yusuke; Kimura, Akio [Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima 739-8526 (Japan); Taniguchi, Masaki [Hiroshima Synchrotron Radiation Center, Hiroshima University, 2-313 Kagamiyama, Higashi-Hiroshima 739-0046 (Japan); Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima 739-8526 (Japan)

2012-12-15T23:59:59.000Z

277

X-RAY FLUORESCENCE MICROPROBE (XFM) TECHNIQUES AND CAPABILITIES  

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

RAY FLUORESCENCE MICROPROBE (XFM) RAY FLUORESCENCE MICROPROBE (XFM) TECHNIQUES AND CAPABILITIES APPLICATIONS WORLD-LEADING MICROFOCUSED EXAFS SPECTROSCOPY * XFM is an optimized three-pole wiggler beamline for the characterization of materials in an "as-is" state that are chemically heterogeneous at the micrometer scale via synchrotron induced X-ray fluorescence. * XFM includes instrumentation for microbeam X-ray fluorescence (µXRF), diffraction (µXRD) and fluorescence computed microtomography (FCMT) . However, it is optimized to provide users state-of-the-art microfocused Extended X-ray Absorption Fine Structure (µEXAFS) spectroscopy between 4 to 20 keV. * XFM will trade-off beam size and flux for sample configuration flexibility. This includes more readily achievable stability

278

X-ray photoelectron spectroscopy and ultraviolet photoelectron spectroscopy investigation of Al-related dipole at the HfO{sub 2}/Si interface  

SciTech Connect

The presence of an ultrathin oxide layer at the high-k/SiO{sub 2} interface may result in an interfacial dipole related to the specific high-k dielectric used for the gate stacks. 1 nm HfO{sub 2}/x nmAl{sub 2}O{sub 3}/SiO{sub 2}/Si stacks with different x values (x=0, 0.4, 0.8, 1.2) have been prepared by atomic layer deposition. Using photoelectron spectroscopy, an Al-related interfacial dipole in the HfO{sub 2}/Al{sub 2}O{sub 3}/SiO{sub 2} gate stack has been identified. X-ray photoelectron spectroscopy analysis shows that the dipole is correlated with the formation of an interfacial Al-silicate. The dipole is located at the Al-silicate interface between Al{sub 2}O{sub 3} and SiO{sub 2}, and its strength increases with the increase in Al{sub 2}O{sub 3} thickness because of Al silicate growth. Such Al-related interfacial dipole should have potential applications in future positive metal-oxide-semiconductor devices.

Zhu, L. Q.; Barrett, N.; Jegou, P. [Groupe Photoemission, CEA/IRAMIS/SPCSI, F-91191 Gif-sur-Yvette (France); Martin, F.; Leroux, C.; Martinez, E.; Grampeix, H.; Renault, O.; Chabli, A. [CEA-LETI, MINATEC, 17 rue des Martyrs, 38054 Grenoble Cedex 9 (France)

2009-01-15T23:59:59.000Z

279

E-Print Network 3.0 - absorption edge detector Sample Search...  

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

XAFS , x-ray ab- sorption near-edge spectroscopy XANES and diffraction anomalous... of a standard sample, with known absorption edge features at tabulated energies, and 3...

280

Methods development for diffraction and spectroscopy studies of metalloenzymes at X-ray free-electron lasers  

Science Journals Connector (OSTI)

...Coherent Light Source, taking...Coherent Light Source (LCLS...radiation energy by the X-ray...developed by us to process...large sample consumption is not sustainable...Coherent Light Source (LCLS...operated for the US Department of Energy Office of...

2014-01-01T23:59:59.000Z

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


281

X-ray Imaging Workshop  

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

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

282

Simultaneous measurement of x-ray absorption spectra and kinetics : a fixed-bed, plug-flow operando reactor.  

SciTech Connect

An inexpensive fixed-bed, plug-flow operando reactor is described in which X-ray absorbance and kinetic data can be measured simultaneously. Pt L3 (11.56 keV) XANES and EXAFS data were obtained on a 1.5% Pt/silica catalyst in borosilicate glass reactors of different diameters, 3-6 mm, and thicknesses, 0.3-1.2 mm, some of which are capable of operation at pressures up to about 40 atm. Additionally, polyimide tubular reactors with low absorbance can be used for lower energy edges of the 3d transition metals, or fluorescence detection for low concentration or highly absorbing supports. With the polyimide reactor, however, the pressure is limited to {approx}3.5 atm and the reaction temperature to about 300 C. To validate the reactor, the rate and activation energies for the water-gas shift reaction on 2% Pd, 13.7% Zn on Al2O3 catalyst were within 15% of those obtained in a standard laboratory reactor, which is within laboratory reproducibility. In addition, the Pd K edge (24.35 keV) XANES and EXAFS data on pre-reduced catalyst were identical to that previously determined on a regular cell. The EXAFS data show that the degree of Pd-Zn alloy formation changes with reaction temperature demonstrating the importance of characterizing the catalyst under reaction conditions.

Fingland, B. R.; Ribeiro, F. H.; Miller, J. T.; Purdue Univ.

2009-08-01T23:59:59.000Z

283

Electronic structures and bonding properties of chlorine-treated nitrogenated carbon nanotubes: X-ray absorption and scanning photoelectron microscopy studies  

SciTech Connect

The electronic and bonding properties of nitrogenated carbon nanotubes (N-CNTs) exposed to chlorine plasma were investigated using C and N K-edge x-ray absorption near-edge structure (XANES) and scanning photoelectron microscopy (SPEM). The C and N K-edge XANES spectra of chlorine-treated N-CNTs consistently reveal the formation of pyridinelike N-CNTs by the observation of 1s{yields}{pi}*(e{sub 2u}) antibonding and 1s{yields}{pi}*(b{sub 2g}) bonding states. The valence-band photoemission spectra obtained from SPEM images indicate that chlorination of the nanotubes enhances the C-N bonding. First-principles calculations of the partial densities of states in conjunction with C K-edge XANES data identify the presence of C-Cl bonding in chlorine treated N-CNTs.

Ray, S. C.; Pao, C. W.; Tsai, H. M.; Chiou, J. W.; Pong, W. F.; Chen, C. W.; Tsai, M.-H.; Papakonstantinou, P.; Chen, L. C.; Chen, K. H.; Graham, W. G. [Department of Physics, Tamkang University, Tamsui 251, Taiwan (China); Department of Materials Science and Engineering, National Taiwan University, Taipei 106, Taiwan (China); Department of Physics, National Sun Yat-Sen University, Kaohsiung 804, Taiwan (China); NRI, School of Electrical and Mechanical Engineering, University of Ulster at Jordanstown, Newtownabbey, County Antrim BT37OQB, Northern Ireland (United Kingdom); Center for Condensed Matter Sciences, National Taiwan University, Taipei 106, Taiwan (China); Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 106, Taiwan (China); Department of Physics and Astronomy, Queens University of Belfast, Belfast, Antrim BT71NN, Northern Ireland (United Kingdom)

2007-05-07T23:59:59.000Z

284

X-ray Absorption Spectroscopy Study of Prototype Chemical Systems: Theory vs. Experiment  

E-Print Network (OSTI)

E. Teller, Zeitschrift Fur Physikalische Chemie-AbteilungB-Chemie Der Elementarprozesse Aufbau Der Materie 21 (5/6),Zeitschrift Fur Physikalische Chemie-Abteilung B-Chemie Der

Schwartz, Craig Philip

2010-01-01T23:59:59.000Z

285

Solving the structure of reaction intermediates by time-resolved synchrotron x-ray absorption spectroscopy  

E-Print Network (OSTI)

metal oxides CuO,1 Cu-ceria,2 Au-ceria,3 and Cu­MoO2 Ref. 4 in water-gas- shift reactions. Another area catalysts where we detected reaction intermediates and measured fine details of the reaction kinetics and 12 have been also applied to study intermediate state structure and deter- mine reaction kinetic

Frenkel, Anatoly

286

The structure of interfacial water on gold electrodes studied by x-ray absorption spectroscopy  

Science Journals Connector (OSTI)

...perpendicular to the surface (SD || green, SD? blue), and double donor (DD...Our calculations indicate that the low-energy core-excited states of the interfacial...electrocatalysis, photo-chemistry, energy storage and others. References and Notes 1 A. J. Bard...

Juan-Jesus Velasco-Velez; Cheng Hao Wu; Tod A. Pascal; Liwen F. Wan; Jinghua Guo; David Prendergast; Miquel Salmeron

287

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

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

Rev. Sci. Instrum. 85, 074103 (2014) DOI: 10.10631.4890816 1.4890816.figures.online.f1 Abstract: A simple gas cell design, constructed primarily from commercially available...

288

AN X-RAY ABSORPTION SPECTROSCOPY STUDY OF MANGANESE CONTAINING COMPOUNDS AND PHOTOSYNTHETIC SPINACH CHLOROPLASTS  

E-Print Network (OSTI)

oxygen evolving capabilities. These preparations are reported to have 4-6 manganese atoms per photochemical reaction center(

Kirby, Jon Allan

2012-01-01T23:59:59.000Z

289

In Situ Electrochemical X-ray Absorption Spectroscopy of Oxygen Reduction Electrocatalysis with High Oxygen Flux  

E-Print Network (OSTI)

to the widespread application of fuel cells and air-cathode batteries in automotive and stationary power a progressive evolution of the electronic structure of the metal clusters that is both potential) and the large overpotential (300 mV) in fuel cell cathodes necessitate the use of high loadings of precious-metal

Frenkel, Anatoly

290

The structure of interfacial water on gold electrodes studied by x-ray absorption spectroscopy  

Science Journals Connector (OSTI)

...perpendicular to the surface (SD || green, SD? blue), and double-donor...Our calculations indicate that the low-energy core-excited states of the interfacial...electrocatalysis, photochemistry, and energy storage, among others. References and Notes 1 A. J. Bard, L. R...

Juan-Jesus Velasco-Velez; Cheng Hao Wu; Tod A. Pascal; Liwen F. Wan; Jinghua Guo; David Prendergast; Miquel Salmeron

2014-11-14T23:59:59.000Z

291

A New Beamline For Time Resolved And Extreme Conditions X-Ray Absorption Spectroscopy  

SciTech Connect

The ESRF has recently started an ambitious project spread over 10 years aimed at an upgrade of the accelerator, beamlines and infrastructure. Through this upgrade, we are proposing a refurbishment of the scanning EXAFS beamline BM29 and of the Energy Dispersive XAS (EDXAS) beamline ID24.

Mathon, Olivier; Mairs, Trevor; Pascarelli, Sakura [ESRF, BP220, 38043 Grenoble Cedex (France)

2010-06-23T23:59:59.000Z

292

Characterization of selective binding of alkali cations with carboxylate by x-ray absorption spectroscopy  

E-Print Network (OSTI)

spectra measured for aqueous formate and acetate solutions containing lithium, sodium, and potassium simulations and other experi- ments. The carbon K-edge spectra of the acetate carbonyl feature centered near with the carboxylate groups of the model carboxylate anions formate and acetate, using liquid microjet technology

Cohen, Ronald C.

293

X-ray Absorption Spectroscopy Study of Prototype Chemical Systems: Theory vs. Experiment  

E-Print Network (OSTI)

with detailed electronic structure calculations is detailed.geometries for electronic structure calculations. Thiscoordinates for electronic structure calculations, has

Schwartz, Craig Philip

2010-01-01T23:59:59.000Z

294

X-ray Absorption Spectroscopy Study of Prototype Chemical Systems: Theory vs. Experiment  

E-Print Network (OSTI)

from the fundamental energy dispersion of electronic statesfrom the fundamental energy dispersion of certain electronicfrom the fundamental energy dispersion of certain electronic

Schwartz, Craig Philip

2010-01-01T23:59:59.000Z

295

Hazards analysis for the E.O. Lawrence Berkeley National Laboratory x-ray absorption experiments to be performed at Stanford Synchrotron Radiation Laboratory  

SciTech Connect

The objective of this experiment is to determine the oxidation state(s) of neptunium (Np) in mouse skeleton and in soft tissue by X-ray Absorption Near Edge Structure (XANES). If Np is present in sufficient concentration, X-ray Absorption Fine Structure (XAFS) data will be obtained in order to further identify the Np species present. These data will be crucial in understanding the metabolic pathway of Np in mammals which will help in the design of reagents which can eliminate Np from mammals in the event of accidental exposure. It is proposed to run these experiments at the Standard Synchrotron Radiation Laboratory (SSRL). This laboratory is a DOE national user facility located at the Stanford Linear Accelerator Center (SLAC). The {sup 237}Np nucleus decays by the emission of an alpha particle and this particle emission is the principal hazard in handling Np samples. This hazard is mitigated by physical containment of the sample which stops the alpha particles within the containment. The total amount of Np material that will be shipped to and be at SSRL at any one time will be less than 1 gram. This limit on the amount of Np will ensure that SLAC remains a low hazard, non-nuclear facility. The Np samples will be solids or Np ions in aqueous solution. The Np samples will be shipped to SSRL/SLAC OHP. SLAC OHP will inventory the samples and swipe the containers holding the triply contained samples, and then bring them to the SSRL Actinide trailer located outside building 131. The QA counting records from the samples, as measured at LBNL, will be provided to SSRL and SLAC OHP prior to the arrival of the samples at SLAC OHP. In addition, strict monitoring of the storage and experimental areas will be performed in accordance with SLAC/OHP radiation protection procedures to ensure against the release of contamination.

Edelstein, N.M.; Shuh, D.K.; Bucher, J.B. [Lawrence Berkeley National Lab., CA (United States). Chemical Sciences Div.

1995-04-01T23:59:59.000Z

296

A Sealed, UHV Compatible, Soft X-ray Detector Utilizing Gas Electron Multipliers  

SciTech Connect

An advanced soft X-ray detector has been designed and fabricated for use in synchrotron experiments that utilize X-ray absorption spectroscopy in the study a wide range of materials properties. Fluorescence X-rays, in particular C{sub K} at 277eV, are converted in a low pressure gas medium, and charge multiplication occurs in two gas electron multipliers, fabricated in-house from glass reinforced laminate, to enable single photon counting. The detector satisfies a number of demanding characteristics often required in synchrotron environments, such as UHV compatibility compactness, long-term stability, and energy resolving capability.

Schaknowski, N.A.; Smith, G.

2009-10-25T23:59:59.000Z

297

BROADBAND ESO/VISIR-SPITZER INFRARED SPECTROSCOPY OF THE OBSCURED SUPERGIANT X-RAY BINARY IGR J16318-4848  

SciTech Connect

A new class of X-ray binaries has recently been discovered by the high-energy observatory INTEGRAL. It is composed of intrinsically obscured supergiant high-mass X-ray binaries, unveiled by means of multi-wavelength X-ray, optical, near- and mid-infrared observations, in particular, photometric and spectroscopic observations using ESO facilities. However, the fundamental questions about these intriguing sources, namely, their formation, evolution, and the nature of their environment, are still unsolved. Among them, IGR J16318-4848, a compact object orbiting around a supergiant B[e] star, seems to be one of the most extraordinary celestial sources of our Galaxy. We present here new ESO/Very Large Telescope (VLT) VISIR mid-infrared (MIR) spectroscopic observations of this source. First, line diagnostics allow us to confirm the presence of absorbing material (dust and cold gas) enshrouding the whole binary system, and to characterize the nature of this material. Second, by fitting broadband near- to mid-infrared spectral energy distribution, including ESO NTT/SofI, VLT/VISIR, and Spitzer data, with a phenomenological model for sgB[e] stars, we show that the star is surrounded by an irradiated rim heated to a temperature of {approx}3800-5500 K, along with a viscous disk component at an inner temperature of {approx}750 K. VISIR data allow us to exclude the spherical geometry for the dust component. This detailed study will allow us in the future to get better constraints on the formation and evolution of such rare and short-living high-mass X-ray binary systems in our Galaxy.

Chaty, S.; Rahoui, F., E-mail: sylvain.chaty@cea.fr, E-mail: frahoui@cfa.harvard.edu [AIM (UMR-E 9005 CEA/DSM-CNRS-Universite Paris Diderot) Irfu/Service d'Astrophysique, Centre de Saclay, FR-91191 Gif-sur-Yvette Cedex (France)

2012-06-01T23:59:59.000Z

298

Does a Fast Nuclear Magnetic Resonance Spectroscopy- and X-Ray Crystallography Hybrid Approach Provide Reliable Structural Information of Ligand-Protein Complexes? A Case Study of Metalloproteinases  

Science Journals Connector (OSTI)

Does a Fast Nuclear Magnetic Resonance Spectroscopy- and X-Ray Crystallography Hybrid Approach Provide Reliable Structural Information of Ligand-Protein Complexes? ... In brief, a grid box of 70 Å × 70 Å × 70 Å was centered on the active site (the residue cluster displaying chemical shift perturbation upon inhibitor addition) with a grid spacing of 0.375 Å. Crossover-, mutation-, and elitism weights were set to 0.80, 0.02, and 1.0, respectively. ... Support from the EU-NMR Integrated Infrastructure Initiative, contract no. ...

Johan Isaksson; Susanne Nyström; Dean Derbyshire; Hans Wallberg; Tatiana Agback; Helena Kovacs; Ivano Bertini; Andrea Giachetti; Claudio Luchinat

2009-02-24T23:59:59.000Z

299

Determination of Fe charge-state distributions in the Princeton large torus by Bragg crystal x-ray spectroscopy  

Science Journals Connector (OSTI)

A curved-crystal Bragg x-ray spectrometer has been used to measure K? or 1s-2p radiation from highly stripped Fexviii-Fexxv impurity ions in the Princeton large torus tokamak. The spectrometer has sufficient energy resolution (?4 eV at 6400 eV) to distinguish between the different ionization states of iron by measuring the energy shift of the K? x rays. The measured wavelengths agree well with theory and with spectra from solar flares and from laser-produced plasmas. The distribution of Fe charge states in the center of the discharge has been inferred from a comparison of the measured x-ray spectrum with theory. The shape of the spectrum depends strongly on electron temperature (Te) in the range Te=800-1500 eV. Within the factor of 2 uncertainty in L-shell ionization cross sections, measured intensities agree with theory, which is based on coronal equilibrium, indicating that the ion lifetime in the center of the plasma is approximately equal to or greater than the equilibration time.

K. W. Hill; S. von Goeler; M. Bitter; L. Campbell; R. D. Cowan; B. Fraenkel; A. Greenberger; R. Horton; J. Hovey; W. Roney; N. R. Sauthoff; W. Stodiek

1979-04-01T23:59:59.000Z

300

Polarization-enhanced absorption spectroscopy for laser stabilization  

Science Journals Connector (OSTI)

We demonstrate a variation of pump-probe spectroscopy that is particularly useful for laser frequency stabilization. The polarization-enhanced absorption spectroscopy (POLEAS) signal...

Kunz, Paul D; Heavner, Thomas P; Jefferts, Steven R

2013-01-01T23:59:59.000Z

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


301

Hard and Soft X-ray Absorption Spectroscopic Investigation of Aqueous Fe(III)?Hydroxamate Siderophore Complexes  

Science Journals Connector (OSTI)

19 The atmospheric pressure was maintained inside the sample chamber by placing a 0.16 ?m silicon nitride window between the sample chamber and upstream ultrahigh vacuum environment. ... The absorption spectra were recorded by detecting sample fluorescence (F) using a gallium arsenide photodiode (Hamamatsu Corporation). ... In aqueous solutions, the solubility of Fe(III) is extremely low close to neutral pH and the Fe(III) concentration increases in acidic and alkaline solutions (Figure 2). ...

David C. Edwards; Satish C. B. Myneni

2005-10-21T23:59:59.000Z

302

Dopant Site Determination in Iron Oxide Nanoparticles Utilizing X-ray  

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

Dopant Site Determination in Iron Oxide Nanoparticles Utilizing X-ray Dopant Site Determination in Iron Oxide Nanoparticles Utilizing X-ray Absorption Techniques Monday, September 9, 2013 - 11:00am SLAC, Conference Room 137-322 Presented by Dr. Vanessa Pool The dopant behavior of spinels has been investigated for over half a century and yet new insight into this class of materials is still being made today. In this work, the question of dopant site preference is explored for the nanoparticle regime. Iron oxide nanoparticles have numerous exciting applications. To realize these applications, controlling the preferred dopant site and valence within the host material is important. X-ray Absorption Spectroscopy (XAS) and X-ray Magnetic Circular Dichroism (XMCD) are element specific techniques with magnetic contrast that give insights into the material composition. Using both

303

A combined fit of total scattering and extended x-ray absorption fine structure data for local-structure determination in crystalline materials  

SciTech Connect

Reverse Monte Carlo (RMC) refinements of local structure using a simultaneous fit of X-ray/neutron total scattering and extended X-ray absorption fine structure (EXAFS) data were developed to incorporate an explicit treatment of both single- and multiple-scattering contributions to EXAFS. The refinement algorithm, implemented as an extension to the public domain computer software RMCProfile, enables accurate modeling of EXAFS over distances encompassing several coordination shells around the absorbing species. The approach was first tested on Ni, which exhibits extensive multiple scattering in EXAFS, and then applied to perovskite-like SrAl{sub 1/2}Nb{sub 1/2}O{sub 3}. This compound crystal1izes with a cubic double-perovskite structure but presents a challenge for local-structure determination using a total pair-distribution function (PDF) alone because of overlapping peaks of the constituent partial PDFs (e.g. Al-O and Nb-O or Sr-O and O-O). The results obtained here suggest that the combined use of the total scattering and EXAFS data provides sufficient constraints for RMC refinements to recover fine details of local structure in complex perovskites. Among other results, it was found that the probability density distribution for Sr in SrAl{sub 1/2}Nb{sub 1/2}O{sub 3} adopts T{sub d} point-group symmetry for the Sr sites, determined by the ordered arrangement of Al and Nb, as opposed to a spherical distribution commonly assumed in traditional Rietveld refinements.

Proffen, Thomas E [Los Alamos National Laboratory; Krayzman, Victor [NIST; Levin, Igor [NIST; Tucker, Matt [ISIS, UK

2009-01-01T23:59:59.000Z

304

SPECIES DETERMINATION OF ORGANOMETALLIC COMPOUNDS USING ZEEMAN ATOMIC ABSORPTION SPECTROSCOPY WITH LIQUID CHROMATOGRAPHY  

E-Print Network (OSTI)

Compounds Using Zeeman Atomic Absorption Spectroscopy WithCompounds Using Zeeman ,Atomic Absorption Spectroscopy withcapabilities of Zeeman atomic absorption spectroscopy (ZAA)

Koizumi, H.

2011-01-01T23:59:59.000Z

305

The scanning soft X-ray microscope at Hasylab: imaging and spectroscopy of photoelectrons, photoluminescence, desorbed ions, reflected, scattered and transmitted light  

Science Journals Connector (OSTI)

The scanning soft X-ray microscope operating at Hasylab/Desy has been developed to combine lateral and temporal resolution, tunability and various conventional spectroscopy techniques. Different mirror optics are used to form a microprobe in the energy range 15–1500 eV. A grazing incidence ellipsoidal mirror provides a resolution of 1 ?m over the entire energy range, and in the vacuum ultraviolet region below 30 eV, 0.15 ?m can be achieved with a Pt-coated Schwarzschild objective. Due to the large working distance of the optics used, the detection and analysis of several surface signals are comparatively simple. Detectors and spectrometers for photoelectrons, luminescence, fluorescence, desorbed ions, reflected, scattered and transmitted light are built in permanently into the microscope. Furthermore, some combinations of the different methods can be used for simultaneous measurements. In this paper the technical developments of recent years are described. A short representation of some exemplary applications will give an insight into the work of our group and illustrate the characteristics of the microscope. The following topics are discussed: cross-luminescence of barium fluoride, visible luminescence and degradation of porous silicon, photoluminescence of ceramics, chemical contrast in photoemission spectroscopy, and Bragg reflection as a contrast mechanism in X-ray microscopy.

J Voss

1997-01-01T23:59:59.000Z

306

Double-core excitations in formamide can be probed by X-ray double-quantum-coherence spectroscopy  

SciTech Connect

The attosecond, time-resolved X-ray double-quantum-coherence four-wave mixing signals of formamide at the nitrogen and oxygen K-edges are simulated using restricted excitation window time-dependent density functional theory and the excited core hole approximation. These signals, induced by core exciton coupling, are particularly sensitive to the level of treatment of electron correlation, thus providing direct experimental signatures of electron and core-hole many-body effects and a test of electronic structure theories.

Zhang Yu; Healion, Daniel; Biggs, Jason D.; Mukamel, Shaul [Department of Chemistry, University of California, 450 Rowland Hall, Irvine, California 92697 (United States)

2013-04-14T23:59:59.000Z

307

High-resolution X-ray spectroscopy of hollow atoms created in plasma heated by subpicosecond laser radiation  

SciTech Connect

The investigations of ultrashort (0.4-0.6 ps) laser pulse radiation interaction with solid targets have been carried out. The Trident subpicosecond laser system was used for plasma creation. The X-ray plasma emission was investigated with the help of high-resolution spectrographs with spherically bent mica crystals. It is shown that when high contrast ultrashort laser pulses were used for plasma heating its emission spectra could not be explained in terms of commonly used theoretical models, and transitions in so called {open_quotes}hollow atoms{close_quotes} must be taken into account for adequate description of plasma radiation.

Faenov, A.Ya.; Magunov, A.I.; Pikuz, T.A. [Multicharged Ions Spectra Data Center of VNIIFTRI, Moscow (Russian Federation)] [and others

1997-10-01T23:59:59.000Z

308

Hyperfine Studies of Lithium Vapor using Saturated Absorption Spectroscopy  

E-Print Network (OSTI)

the frequency of a laser with respect to an atomic spectral feature.[20] As such, saturated absorptionHyperfine Studies of Lithium Vapor using Saturated Absorption Spectroscopy? . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 3.3 Broadening Mechanisms . . . . . . . . . . . . . . . . . . . . . 15 3.4 Saturated Absorption

Cronin, Alex D.

309

First Results On Shear-Selected Clusters From the Deep Lens Survey: Optical Imaging, Spectroscopy, and X-ray Followup  

E-Print Network (OSTI)

We present the first sample of galaxy clusters selected on the basis of their weak gravitational lensing shear. The shear induced by a cluster is a function of its mass profile and its redshift relative to the background galaxies being sheared; in contrast to more traditional methods of selecting clusters, shear selection does not depend on the cluster's star formation history, baryon content, or dynamical state. Because mass is the property of clusters which provides constraints on cosmological parameters, the dependence on these other parameters could induce potentially important biases in traditionally-selected samples. Comparison of a shear-selected sample with optically and X-ray selected samples is therefore of great importance. Here we present the first step toward a new shear-selected sample: the selection of cluster candidates from the first 8.6 deg$^2$ of the 20 deg$^2$ Deep Lens Survey (DLS), and tabulation of their basic properties such as redshifts and optical and X-ray counterparts.

Wittman, D; Hughes, J P; Margoniner, V E; Tyson, J A; Cohen, J G; Norman, D

2006-01-01T23:59:59.000Z

310

First Results On Shear-Selected Clusters From the Deep Lens Survey: Optical Imaging, Spectroscopy, and X-ray Followup  

E-Print Network (OSTI)

We present the first sample of galaxy clusters selected on the basis of their weak gravitational lensing shear. The shear induced by a cluster is a function of its mass profile and its redshift relative to the background galaxies being sheared; in contrast to more traditional methods of selecting clusters, shear selection does not depend on the cluster's star formation history, baryon content, or dynamical state. Because mass is the property of clusters which provides constraints on cosmological parameters, the dependence on these other parameters could induce potentially important biases in traditionally-selected samples. Comparison of a shear-selected sample with optically and X-ray selected samples is therefore of great importance. Here we present the first step toward a new shear-selected sample: the selection of cluster candidates from the first 8.6 deg$^2$ of the 20 deg$^2$ Deep Lens Survey (DLS), and tabulation of their basic properties such as redshifts and optical and X-ray counterparts.

D. Wittman; I. P. Dell'Antonio; J. P. Hughes; V. E. Margoniner; J. A. Tyson; J. G. Cohen; D. Norman

2005-07-26T23:59:59.000Z

311

X-ray Observations of Mrk 231  

E-Print Network (OSTI)

This paper presents new X-ray observations of Mrk 231, an active galaxy of particular interest due to its large infrared luminosity and the presence of several blueshifted broad absorption line (BAL) systems, a phenomenon observed in a small fraction of QSOs. A ROSAT HRI image of Mrk 231 is presented, this shows an extended region of soft X-ray emission, covering several tens of kpc, consistent with the extent of the host galaxy. An ASCA observation of Mrk 231 is also presented. Hard X-rays are detected but the data show no significant variability in X-ray flux. The hard X-ray continuum is heavily attenuated and X-ray column estimates range from ~ 2 x 10^{22} - 10^{23} cm^{-2} depending on whether the material is assumed to be neutral or ionized, and on the model assumed for the extended X-ray component. These ASCA data provide only the second hard X-ray spectrum of a BAL AGN presented to date. The broad-band spectral-energy-distribution of the source is discussed. While Mrk 231 is X-ray weak compared to Seyfert 1 galaxies, it has an optical-to-X-ray spectrum typical of a QSO.

T. J. Turner

1998-08-10T23:59:59.000Z

312

Upgraded high time-resolved x-ray imaging crystal spectroscopy system for J-TEXT ohmic plasmas  

SciTech Connect

This paper presents the upgraded x-ray imaging crystal spectrometer (XICS) system on Joint Texas Experimental Tokamak (J-TEXT) tokamak and the latest experimental results obtained in last campaign. With 500 Hz frame rate of the new Pilatus detector and 5 cm × 10 cm spherically bent crystal, the XICS system can provide core electron temperature (T{sub e}), core ion temperature (T{sub i}), and plasma toroidal rotation (V{sub ?}) with a maximum temporal resolution of 2 ms for J-TEXT pure ohmic plasmas. These parameters with high temporal resolution are very useful in tokamak plasma research, especially for rapidly changed physical processes. The experimental results from the upgraded XICS system are presented.

Jin, W.; Chen, Z. Y., E-mail: zychen@hust.edu.cn; Huang, D. W.; Li, Q. L.; Yan, W.; Luo, Y. H.; Huang, Y. H.; Tong, R. H.; Yang, Z. J.; Rao, B.; Ding, Y. H.; Zhuang, G. [State Key Laboratory of Advanced Electromagnetic Engineering and Technology, School of Electrical and Electronic Engineering, Huazhong University of Science and Technology, Wuhan 430074 (China)] [State Key Laboratory of Advanced Electromagnetic Engineering and Technology, School of Electrical and Electronic Engineering, Huazhong University of Science and Technology, Wuhan 430074 (China); Lee, S. G.; Shi, Y. J. [National Fusion Research Institute, Daejeon 305-333 (Korea, Republic of)] [National Fusion Research Institute, Daejeon 305-333 (Korea, Republic of)

2014-02-15T23:59:59.000Z

313

Harmonic wavelet analysis of modulated tunable diode laser absorption spectroscopy signals  

E-Print Network (OSTI)

of the direct absorption characteristics of atomic or molecular absorption lines. This is accomplishedHarmonic wavelet analysis of modulated tunable diode laser absorption spectroscopy signals Hong analyses of tunable diode laser absorption spectroscopy signals were performed. The absorption spectroscopy

Cheng, Harry H.

314

In situ apparatus for the study of clathrate hydrates relevant to solar system bodies using synchrotron X-ray diffraction and Raman spectroscopy  

E-Print Network (OSTI)

Clathrate hydrates are believed to play a significant role in various solar system environments, e.g. comets, and the surfaces and interiors of icy satellites, however the structural factors governing their formation and dissociation are poorly understood. We demonstrate the use of a high pressure gas cell, combined with variable temperature cooling and time-resolved data collection, to the in situ study of clathrate hydrates under conditions relevant to solar system environments. Clathrates formed and processed within the cell are monitored in situ using synchrotron X-ray powder diffraction and Raman spectroscopy. X-ray diffraction allows the formation of clathrate hydrates to be observed as CO2 gas is applied to ice formed within the cell. Complete conversion is obtained by annealing at temperatures just below the ice melting point. A subsequent rise in the quantity of clathrate is observed as the cell is thermally cycled. Four regions between 100-5000cm-1 are present in the Raman spectra that carry feature...

Day, Sarah J; Evans, Aneurin; Parker, Julia E

2015-01-01T23:59:59.000Z

315

Assignment of near-edge x-ray absorption fine structure spectra of metalloporphyrins by means of time-dependent density-functional calculations  

SciTech Connect

The C 1s and N 1s near-edge x-ray absorption fine structure (NEXAFS) spectra of three prototype tetraphenyl porphyrin (TPP) molecules are discussed in the framework of a combined experimental and theoretical study. We employ time-dependent density-functional theory (TDDFT) to compute the NEXAFS spectra of the open- and closed-shell metalloporphyrins CoTPP and ZnTPP as well as the free-base 2HTPP in realistic nonplanar conformations. Using Becke's well-known half-and-half hybrid functional, the computed core excitation spectra are mostly in good agreement with the experimental data in the low-energy region below the appropriate ionization threshold. To make these calculations feasible, we apply a new, simple scheme based on TDDFT using a modified single-particle input spectrum. This scheme is very easy to implement in standard codes and allows one to compute core excitation spectra at a similar cost as ordinary UV/vis spectra even for larger molecules. We employ these calculations for a detailed assignment of the NEXAFS spectra including subtle shifts in certain peaks of the N 1s spectra, which depend on the central coordination of the TPP ligand. We furthermore assign the observed NEXAFS resonances to the individual molecular subunits of the investigated TPP molecules.

Schmidt, Norman; Fink, Rainer [Department Chemie und Pharmazie, Lehrstuhl fuer Physikalische Chemie II and ICMM, Universitaet Erlangen-Nuernberg, Egerlandstrasse 3, 91058 Erlangen (Germany); Hieringer, Wolfgang [Department Chemie und Pharmazie, Lehrstuhl fuer Theoretische Chemie, Universitaet Erlangen-Nuernberg, Egerlandstrasse 3, 91058 Erlangen (Germany)

2010-08-07T23:59:59.000Z

316

E-Print Network 3.0 - absorption spectroscopy measurements Sample...  

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

A partial sampling of these techniques includes: Absorption spectroscopy Atomic absorption... spectroscopy Auger electron ... Source: Yucca Mountain Project, US...

317

Spectroscopy (XSD) | Advanced Photon Source  

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

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

318

Coal Combustion Fly Ash Characterization: Electron Spectroscopy for Chemical Analysis, Energy Dispersive X-ray Analysis, and Scanning Electron Microscopy  

Science Journals Connector (OSTI)

The surface and bulk properties of five samples of fly ash have been examined by electron spectroscopy for chemical analysis (ESCA), scanning electron microscopy (SEM) and energy...

Rothenberg, S J; Denee, P; Holloway, P

1980-01-01T23:59:59.000Z

319

Multiple-scattering calculations of the uranium {ital L}{sub 3}-edge x-ray-absorption near-edge structure  

SciTech Connect

A theoretical study of the uranium {ital L}{sub 3}-edge x-ray absorption near-edge structure (XANES) is presented for several uranium compounds, including oxides, intermetallics, uranyl fluoride, and {alpha}-uranium. Calculations were performed using FEFF6, an {ital ab} {ital initio} multiple-scattering (MS) code that includes the most important features of current theories. The results, which account for both the fine structure {chi} and the atomiclike background {mu}{sub 0} of the absorption coefficient {mu}, are compared to new and previously measured experimental spectra, reavealing very good agreement for most systems. For several compounds, a more detailed theoretical analysis determined the influence of cluster size and scattering order upon the calculated spectra. Results indicate that MS paths and scattering paths that include rather distant atoms make significant contributions for UO{sub 2}, whereas XANES for crystals with lower symmetry and density can be modeled using only shorter single-scattering paths. In most cases, assumption of a screened final state in the calculation gives better agreement with experiment than use of an unscreened final state. The successful modeling of spectra for a variety of different uranium compounds, with differing spectral features, indicates that the semirelativistic treatment of XANES used here is adequate even for heavy elements. The well-known resonance, observed experimentally for uranyl (UO{sub 2}{sup 2+}) compounds {approx}15 eV above the white line, is successfully modeled here for the first time, using multiple-scattering paths within the O-U-O axial bonds. Overlapping muffin-tin spheres were required in the calculation, probably as a result of the short uranyl axial bonds.

Hudson, E.A. [Glenn T. Seaborg Institute for Transactinium Science, Lawrence Livermore National Laboratory, University of California, Livermore, California 94551 (United States)] [Glenn T. Seaborg Institute for Transactinium Science, Lawrence Livermore National Laboratory, University of California, Livermore, California 94551 (United States); Rehr, J.J. [Department of Physics, University of Washington, Seattle, Washington 98195 (United States)] [Department of Physics, University of Washington, Seattle, Washington 98195 (United States); Bucher, J.J. [Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)] [Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)

1995-11-15T23:59:59.000Z

320

Hard x-ray photoelectron spectroscopy study on band alignment at poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)/ZnO interface  

SciTech Connect

We used hard x-ray photoelectron spectroscopy to investigate the interfacial electronic states of a poly(styrenesulfonate) doped poly(3,4-ethylenedioxythiophene) (PEDOT:PSS) contact on a ZnO single crystal. An understanding of the interfacial band structure is useful for putting the organic contact to practical use. We observed upward band bending of the ZnO layer a few nanometers from the interface. The detected ZnO bulk region exhibited a flat band structure, meaning that the PEDOT:PSS does not greatly deplete the ZnO layer. The band bending caused the charge injection barrier formation with the result that the contact exhibited the Schottky property.

Nagata, T.; Hayakawa, R.; Chikyow, T. [International Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044 (Japan); Oh, S.; Wakayama, Y. [International Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044 (Japan); Department of Chemistry and Biochemistry, Faculty of Engineering, Kyushu University, 1-1 Namiki, Tsukuba 305-0044 (Japan); Yamashita, Y. [International Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044 (Japan); NIMS Beamline Station at SPring-8, National Institute for Materials Science, 1-1-1 Koto, Sayo-cho, Sayo-gun, Hyogo 679-5148 (Japan); Yoshikawa, H.; Kobayashi, K. [NIMS Beamline Station at SPring-8, National Institute for Materials Science, 1-1-1 Koto, Sayo-cho, Sayo-gun, Hyogo 679-5148 (Japan)

2012-10-22T23:59:59.000Z

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


321

Initial stages of ITO/Si interface formation: In situ x-ray photoelectron spectroscopy measurements upon magnetron sputtering and atomistic modelling using density functional theory  

SciTech Connect

Initial stages of indium tin oxide (ITO) growth on a polished Si substrate upon magnetron sputtering were studied experimentally using in-situ x-ray photoelectron spectroscopy measurements. The presence of pure indium and tin, as well as Si bonded to oxygen at the ITO/Si interface were observed. The experimental observations were compared with several atomistic models of ITO/Si interfaces. A periodic model of the ITO/Si interface was constructed, giving detailed information about the local environment at the interface. Molecular dynamics based on density functional theory was performed, showing how metal-oxygen bonds are broken on behalf of silicon-oxygen bonds. These theoretical results support and provide an explanation for the present as well as previous ex-situ and in-situ experimental observations pointing to the creation of metallic In and Sn along with the growth of SiO{sub x} at the ITO/Si interface.

Løvvik, O. M.; Diplas, S.; Ulyashin, A. [SINTEF Materials and Chemistry, Forskningsveien 1, NO-0314 Oslo (Norway); Romanyuk, A. [University of Basel, Kingelbergstr. 82, CH-4056 Basel (Switzerland)

2014-02-28T23:59:59.000Z

322

Measurement of the valence band-offset in a PbSe/ZnO heterojunction by x-ray photoelectron spectroscopy  

SciTech Connect

A heterojunction of PbSe/ZnO has been grown by molecular beam epitaxy. X-ray photoelectron spectroscopy was used to directly measure the valence-band offset (VBO) of the heterojunction. The VBO, {Delta}E{sub V}, was determined as 2.51 {+-} 0.05 eV using the Pb 4p{sup 3/2} and Zn 2p{sup 3/2} core levels as a reference. The conduction-band offset, {Delta}E{sub C}, was, therefore, determined to be 0.59 {+-} 0.05 eV based on the above {Delta}E{sub V} value. This analysis indicates that the PbSe/ZnO heterojunction forms a type I (Straddling Gap) heterostructure.

Li Lin; Qiu Jijun; Weng Binbin; Yuan Zijian; Shi Zhisheng [School of Electrical and Computer Engineering, University of Oklahoma, Norman, Oklahoma 73019 (United States); Li Xiaomin; Gan Xiaoyan [State Key Laboratory of High Performance Ceramics and Superfine Microstructures, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China); Sellers, Ian R. [Deparment of Physics, University of Oklahoma, Norman, Oklahoma 73019 (United States)

2012-12-24T23:59:59.000Z

323

Pressure induced high spin-low spin transition in FeSe superconductor studied by x-ray emission spectroscopy and ab initio calculations  

SciTech Connect

FeSe is a simple binary system in the iron based superconducting family and exhibits a significant pressure induced increase in the superconducting transition temperature (T{sub c}). In addition to pressure effect, spin fluctuations, magnetic ordering, and crystal structure all play vital roles in altering T{sub c}. Even though various experiments and theoretical simulations explain the connection among them and superconductivity, the interplay between these important parameters is still not clearly understood. Here, we report the pressure effect on the spin state of Fe in FeSe superconductor studied using synchrotron x-ray emission spectroscopy at ambient and low temperatures down to 8 K near T{sub c}. Pressure induced high spin to low spin transition was observed at both ambient and low temperatures with continuous suppression of Fe magnetic moments under increasing pressure. The spin transition is closely related to the pressure induced tetragonal to orthorhombic structural transition.

Kumar, Ravhi S.; Zhang, Yi; Xiao, Yuming; Baker, Jason; Cornelius, Andrew; Veeramalai, Sathishkumar; Chow, Paul; Chen, Changfeng; Zhao, Yusheng (UNLV); (CIW)

2011-09-20T23:59:59.000Z

324

Phase transitions in heated Sr{sub 2}MgTeO{sub 6} double perovskite oxide probed by X-ray diffraction and Raman spectroscopy  

SciTech Connect

Double-perovskite oxide Sr{sub 2}MgTeO{sub 6} has been synthetized, and its crystal structure was probed by the technique of X-ray diffraction at room temperature. The structure is monoclinic, space group I2/m. Temperature-induced phase transitions in this compound were investigated by Raman spectroscopy up to 550?°C. Two low-wavenumber modes corresponding to external lattice vibrations merge at temperature of around 100?°C, indicating a phase transition from the monoclinic (I2/m) to the tetragonal (I4/m) structure. At 300?°C, changes in the slopes of temperature dependencies of external and O–Te–O bending modes are detected and interpreted as a second phase transition from the tetragonal (I4/m) to the cubic (Fm-3m) structure.

Manoun, Bouchaib, E-mail: manounb@gmail.com; Tamraoui, Y. [Equipe Ingénierie et environnement, Laboratoire de Chimie Appliquée et Environnement, Université Hassan 1er, Settat 26000 (Morocco)] [Equipe Ingénierie et environnement, Laboratoire de Chimie Appliquée et Environnement, Université Hassan 1er, Settat 26000 (Morocco); Lazor, P. [Department of Earth Sciences, Uppsala University, SE-752 36 Uppsala (Sweden)] [Department of Earth Sciences, Uppsala University, SE-752 36 Uppsala (Sweden); Yang, Wenge [High Pressure Synergetic Consortium, Geophysical Laboratory, Carnegie Institution of Washington, Argonne, Illinois 60439, USA and Center for High Pressure Science and Technology Advanced Research (HPSTAR), Shanghai 201203 (China)] [High Pressure Synergetic Consortium, Geophysical Laboratory, Carnegie Institution of Washington, Argonne, Illinois 60439, USA and Center for High Pressure Science and Technology Advanced Research (HPSTAR), Shanghai 201203 (China)

2013-12-23T23:59:59.000Z

325

Kinetic study of GeO disproportionation into a GeO{sub 2}/Ge system using x-ray photoelectron spectroscopy  

SciTech Connect

GeO disproportionation into GeO{sub 2} and Ge is studied through x-ray photoelectron spectroscopy. Direct evidence for the reaction 2GeO {yields} GeO{sub 2} + Ge after annealing in ultra-high vacuum is presented. Activation energy for GeO disproportionation is found to be about 0.7 {+-} 0.2 eV through kinetic and thermodynamic calculations. A kinetic model of GeO disproportionation is established by considering oxygen transfer in the GeO network. The relationship between GeO disproportionation and GeO desorption induced by GeO{sub 2}/Ge interfacial reaction is discussed, and the apparent contradiction between GeO desorption via interfacial redox reaction and GeO disproportionation into Ge and GeO{sub 2} is explained by considering the oxygen vacancy.

Wang Shengkai [Micorowave Devices and Integrated Circuits Department, Institute of Microelectronics, Chinese Academy of Sciences, 3 Bei-Tu-Cheng West Road, Beijing 100029 (China); Department of Materials Engineering, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); CREST, Japan Science and Technology Agency (JST), 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Liu Honggang [Microwave Devices and Integrated Circuits Department, Institute of Microelectronics, Chinese Academy of Sciences, 3 Bei-Tu-Cheng West Road, Beijing 100029 (China); Toriumi, Akira [Department of Materials Engineering, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); CREST, Japan Science and Technology Agency (JST), 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan)

2012-08-06T23:59:59.000Z

326

Impact of Mg concentration on energy-band-depth profile of Mg-doped InN epilayers analyzed by hard X-ray photoelectron spectroscopy  

SciTech Connect

The electronic structures of Mg-doped InN (Mg-InN) epilayers with the Mg concentration, [Mg], ranging from 1 × 10{sup 19} to 5 × 10{sup 19} cm{sup ?3} were systematically investigated by soft and hard X-ray photoelectron spectroscopies. The angle-resolved results on the core-level and valence band photoelectron spectra as a function of [Mg] revealed that the energy band of Mg-InN showed downward bending due to the n{sup +} surface electron accumulation and p type layers formed in the bulk. With an increase in [Mg], the energy-band changed from monotonic to two-step n{sup +}p homojunction structures. The oxygen concentration rapidly increased at the middle-bulk region (?4.5 to ?7.5 nm) from the surface, which was one of the reasons of the transformation of two-step energy band.

Imura, M.; Tsuda, S.; Nagata, T.; Takeda, H.; Liao, M. Y.; Koide, Y. [National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba, Ibaraki 305-0044 (Japan)] [National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba, Ibaraki 305-0044 (Japan); Yang, A. L.; Yamashita, Y.; Yoshikawa, H.; Kobayashi, K. [NIMS/SPring-8, NIMS, 1-1-1 Koto, Sayo-cho, Sayo, Hyogo 679-5148 (Japan)] [NIMS/SPring-8, NIMS, 1-1-1 Koto, Sayo-cho, Sayo, Hyogo 679-5148 (Japan); Yamaguchi, T. [Faculty of Engineering, Kogakuin University, 2665-1 Nakano-machi, Hachiouji, Tokyo 192-0015 (Japan) [Faculty of Engineering, Kogakuin University, 2665-1 Nakano-machi, Hachiouji, Tokyo 192-0015 (Japan); Faculty of Science and Engineering, Ritsumeikan University, 1-1-1 Noji-Higashi, Kusatsu 525-8577 (Japan); Kaneko, M.; Uematsu, N.; Wang, K.; Araki, T. [Faculty of Science and Engineering, Ritsumeikan University, 1-1-1 Noji-Higashi, Kusatsu 525-8577 (Japan)] [Faculty of Science and Engineering, Ritsumeikan University, 1-1-1 Noji-Higashi, Kusatsu 525-8577 (Japan); Nanishi, Y. [Faculty of Science and Engineering, Ritsumeikan University, 1-1-1 Noji-Higashi, Kusatsu 525-8577 (Japan) [Faculty of Science and Engineering, Ritsumeikan University, 1-1-1 Noji-Higashi, Kusatsu 525-8577 (Japan); Faculty of Materials Science and Engineering, Seoul National University, Seoul 151-744 (Korea, Republic of)

2013-10-14T23:59:59.000Z

327

Development of a Microchannel Plate-Based Gated X-ray Imager for Imaging and Spectroscopy Experiments on Z  

SciTech Connect

This poster describes a microchannelplate (MCP)–based, gated x-ray imager developed by National Security Technologies, LLC (NSTec), and Sandia National Laboratories(SNL) over the past several years. The camera consists of a 40 mm × 40 mm MCP, coated with eight 4 mm wide microstrips. The camera is gated by sending subnanosecond high-voltage pulses across the striplines. We have performed an extensive characterization of the camera, the results of which we present here. The camera has an optical gate profile width (time resolution) as narrow as 150 ps and detector uniformity of better than 30% along the length of a strip, far superior than what was achieved in previous designs. The spatial resolution is on the order of 40 microns for imaging applications and a dynamic range of between ~100 and ~1000. We also present results from a Monte Carlo simulation code developed by NSTec over the last several years. Agreement between the simulation results and the experimental measurements is very good.

Wu, M., Kruschwitz, C. A., Tibbitts, A., Rochau, G.

2011-06-24T23:59:59.000Z

328

Investigation of metal dusting mechanism in Fe-base alloys using Raman spectroscopy, x-ray diffraction, and electron microscopy.  

SciTech Connect

The metal-dusting phenomenon, which is a metal loss process that occurs in hot reactive gases, was investigated in iron and certain iron-base alloys by Raman scattering, X-ray diffraction (XRD), and scanning-electron microscopy (SEM). Coke from metal dusting exhibits six Raman bands at 1330(D band), 1580(G band), 1617, 2685, 3920, and 3235 cm-1. The bandwidths and the relative intensities of the 1330 and 1580 cm-1 bands are related to the crystallinity and defect structure of the coke. Both Raman and XRD analyses suggest that the metal-dusting process influences the catalytic crystallization of carbon. A new mechanism of metal dusting is, therefore, proposed, based on the premise that coke cannot crystallize well by deposition from carburizing gases at low temperature without catalytic activation because of its strong C-C bonds and high melting temperature. Cementite or iron participates in the coke-crystallizing process in a manner that tends to improve the crystallinity of the coke. At the same time, fine iron or cementite particles are liberated from the pure metal or alloys.

Zeng, Z.; Natesan, K.; Maroni, V. A.

2002-08-01T23:59:59.000Z

329

Spectroscopy  

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

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

330

Molecular orientation in soft matter thin films studied by resonant soft X-ray reflectivity  

SciTech Connect

We present a technique to study depth profiles of molecular orientation in soft matter thin films with nanometer resolution. The method is based on dichroism in resonant soft X-ray reflectivity using linear s- and p-polarization. It combines the chemical sensitivity of Near-Edge X-ray Absorption Fine Structure spectroscopy to specific molecular bonds and their orientation relative to the polarization of the incident beam with the precise depth profiling capability of X-ray reflectivity. We demonstrate these capabilities on side chain liquid crystalline polymer thin films with soft X-ray reflectivity data at the carbon K edge. Optical constants of the anisotropic refractive index ellipsoid were obtained from a quantitative analysis using the Berreman formalism. For films up to 50 nm thickness we find that the degree of orientation of the long axis exhibits no depth variation and isindependent of the film thickness.

Mezger, Markus; Jerome, Blandine; Kortright, Jeffrey B.; Valvidares, Manuel; Gullikson, Eric; Giglia, Angelo; Mahne, Nicola; Nannarone, Stefano

2011-01-12T23:59:59.000Z

331

INFRARED ABSORPTION SPECTROSCOPY OF CARBON MONOXIDE ON NICKEL FILMS: A LOW TEMPERATURE THERMAL DETECTION TECHNIQUE  

E-Print Network (OSTI)

A. B. Optical System Absorption Signal C. Small SignalNoise . Sensitivity of Absorption Spectroscopy EXPERIMENTSINFRARED ABSORPTION SPECTROSCOPY OF CARBON MONOXIDE ON

Bailey, Robert Brian

2011-01-01T23:59:59.000Z

332

Pressure-tuning spectroscopy of charge-transfer salts. X-ray crystallography and comparative studies in solution and in the solid state  

SciTech Connect

The highly colored pyridinium (P{sup +}) and cobaltocenium (C{sup +}) iodides are charge-transfer salts by virtue of the new electronic absorption bands that follow Mulliken theory. X-ray crystallography establishes the relevant interionic separation and steric orientation of the cation/anion pairs P{sup +}I{sup {minus}} and C{sup +}I{sup {minus}} constrained for optimum charge-transfer interaction in the crystal lattice. Spectral comparisons of the charge-transfer (CT) transitions by absorption (solution) and by diffuse reflectance (solid-state) measurements reveals the commonality of contact ion pairs (CIP) in aprotic nonpolar solvents (dichloromethane) with those extant in crystalline charge-transfer salts. As such, the compression of the charge-transfer salts P{sup +}I{sup {minus}} in the solid state by the application of pressures up to 140 kbar leads to unusual red shifts of the CT bands indicative of the dominance of destabilizing charge-transfer interactions.

Bockman, T.M.; Kochi, J.K. (Univ. of Houston, TX (USA)); Chang, H.R.; Drickamer, H.G. (Univ. of Illinois, Urbana (USA))

1990-11-01T23:59:59.000Z

333

Electronic structure of a PbFe1/2Nb1/2O3 single crystal in the ferroelectric and paraelectric states, according to X-Ray photoelectron spectroscopy data and first principle calculations  

Science Journals Connector (OSTI)

Electronic structure of the PbFe1/2Nb1/2O3 single crystal is studied by means of X-ray photoelectron spectroscopy on an ESCALAB 250 system and first principle FEFF9 at temperatures of 296 and 403 K.

A. T. Kozakov; O. E. Polozhentsev…

2012-10-01T23:59:59.000Z

334

Direct observation of bias-dependence potential distribution in metal/HfO{sub 2} gate stack structures by hard x-ray photoelectron spectroscopy under device operation  

SciTech Connect

Although gate stack structures with high-k materials have been extensively investigated, there are some issues to be solved for the formation of high quality gate stack structures. In the present study, we employed hard x-ray photoelectron spectroscopy in operating devices. This method allows us to investigate bias dependent electronic states, while keeping device structures intact. Using this method, we have investigated electronic states and potential distribution in gate metal/HfO{sub 2} gate stack structures under device operation. Analysis of the core levels shifts as a function of the bias voltage indicated that a potential drop occurred at the Pt/HfO{sub 2} interface for a Pt/HfO{sub 2} gate structure, while a potential gradient was not observed at the Ru/HfO{sub 2} interface for a Ru/HfO{sub 2} gate structure. Angle resolved photoelectron spectroscopy revealed that a thicker SiO{sub 2} layer was formed at the Pt/HfO{sub 2} interface, indicating that the origin of potential drop at Pt/HfO{sub 2} interface is formation of the thick SiO{sub 2} layer at the interface. The formation of the thick SiO{sub 2} layer at the metal/high-k interface might concern the Fermi level pinning, which is observed in metal/high-k gate stack structures.

Yamashita, Y. [National Institute for Materials Science, Advanced Electric Materials Center, 1-1 Namiki, Tsukuba, Ibaraki 305-0044 (Japan); National Institute for Materials Science, NIMS Beamline Station at SPring-8, 1-1-1 Kôto, Sayo-cho, Sayo-gun, Hyogo 679-5148 (Japan); Yoshikawa, H.; Kobayashi, K. [National Institute for Materials Science, NIMS Beamline Station at SPring-8, 1-1-1 Kôto, Sayo-cho, Sayo-gun, Hyogo 679-5148 (Japan); Chikyo, T. [National Institute for Materials Science, Advanced Electric Materials Center, 1-1 Namiki, Tsukuba, Ibaraki 305-0044 (Japan)

2014-01-28T23:59:59.000Z

335

Spectroscopy  

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

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

336

Spectroscopy  

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

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

337

Chest x-Rays  

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

The B-reading is a special reading of a standard chest x-ray film performed by a physician certified by the National Institute for Occupational Safety and Health (NIOSH). The reading looks for changes on the chest x-ray that may indicate exposure and disease caused by agents such as asbestos or silica.

338

X-ray beamsplitter  

DOE Patents (OSTI)

An x-ray beamsplitter which splits an x-ray beam into two coherent parts by reflecting and transmitting some fraction of an incident beam has applications for x-ray interferometry, x-ray holography, x-ray beam manipulation, and x-ray laser cavity output couplers. The beamsplitter is formed of a wavelength selective multilayer thin film supported by a very thin x-ray transparent membrane. The beamsplitter resonantly transmits and reflects x-rays through thin film interference effects. A thin film is formed of 5--50 pairs of alternate Mo/Si layers with a period of 20--250 A. The support membrane is 10--200 nm of silicon nitride or boron nitride. The multilayer/support membrane structure is formed across a window in a substrate by first forming the structure on a solid substrate and then forming a window in the substrate to leave a free-standing structure over the window. 6 figs.

Ceglio, N.M.; Stearns, D.G.; Hawryluk, A.M.; Barbee, T.W. Jr.

1987-08-07T23:59:59.000Z

339

X-ray beamsplitter  

DOE Patents (OSTI)

An x-ray beamsplitter which splits an x-ray beam into two coherent parts by reflecting and transmitting some fraction of an incident beam has applications for x-ray interferometry, x-ray holography, x-ray beam manipulation, and x-ray laser cavity output couplers. The beamsplitter is formed of a wavelength selective multilayer thin film supported by a very thin x-ray transparent membrane. The beamsplitter resonantly transmits and reflects x-rays through thin film interference effects. A thin film is formed of 5-50 pairs of alternate Mo/Si layers with a period of 20-250 A. The support membrane is 10-200 nm of silicon nitride or boron nitride. The multilayer/support membrane structure is formed across a window in a substrate by first forming the structure on a solid substrate and then forming a window in the substrate to leave a free-standing structure over the window.

Ceglio, Natale M. (Livermore, CA); Stearns, Daniel S. (Mountain View, CA); Hawryluk, Andrew M. (Modesto, CA); Barbee, Jr., Troy W. (Palo Alto, CA)

1989-01-01T23:59:59.000Z

340

X-ray binaries  

E-Print Network (OSTI)

We review the nuclear astrophysics aspects of accreting neutron stars in X-ray binaries. We summarize open astrophysical questions in light of recent observations and their relation to the underlying nuclear physics. Recent progress in the understanding of the nuclear physics, especially of X-ray bursts, is also discussed.

H. Schatz; K. E. Rehm

2006-08-01T23:59:59.000Z

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


341

X-ray induced optical reflectivity  

The change in optical reflectivity induced by intense x-ray pulses can now be used to study ultrafast many body responses in solids in the femtosecond time domain. X-ray absorption creates photoelectrons and core level holes subsequently filled by Auger or fluorescence processes, and these excitations ultimately add conduction and valence band carriers that perturb optical reflectivity.Optical absorption associated with band filling and band gap narrowing is shown to explain the basic features found in recent measurements on an insulator (silicon nitride, Si3N4), a semiconductor(gallium arsenide,GaAs), and a metal (gold,Au), obtained with ?100 fs x-ray pulses at 500-2000 eV and probed with 800 nm laser pulses. In particular GaAs exhibits an abrupt drop in reflectivity, persisting only for a time comparable to the x-ray excitation pulse duration, consistent with prompt band gap narrowing.

Durbin, Stephen M.

2012-01-01T23:59:59.000Z

342

Chemical selective microstructural analysis of thin film using resonant x-ray reflectivity  

SciTech Connect

Strong modulations of the reflected x-ray intensities near the respective absorption edges of the constituent materials promise to determine layer composition of thin film structures along with spectroscopic like information. Near the absorption edge, the orders of magnitude more contrast beyond the pure electron density distributions of materials find an approach to overcome the low density difficulty of the conventional x-ray reflectivity technique. These aspects are explained by experimental studies on partially decomposed boron nitride thin films. Chemical composition profile is determined from free surface to the embedded buried layer with depth resolution in nanometer scale. The results of resonant reflectivity for chemical analysis are correlated with depth dependent x-ray photo electron spectroscopy.

Nayak, Maheswar; Lodha, G. S. [X-ray Optics Section, Indus Synchrotrons Utilization Division, Raja Ramanna Centre for Advanced Technology, Indore 452013, Madhya Pradesh (India)

2013-07-14T23:59:59.000Z

343

In Situ X-Ray Probing Reveals Fingerprints of Surface Platinum Oxide  

SciTech Connect

In situ x-ray absorption spectroscopy (XAS) at the Pt L{sub 3} edge is a useful probe for Pt-O interactions at polymer electrolyte membrane fuel cell (PEMFC) cathodes. We show that XAS using the high energy resolution fluorescence detection (HERFD) mode, applied to a well-defined monolayer Pt/Rh(111) sample where the bulk penetrating hard x-rays probe only surface Pt atoms, provides a unique sensitivity to structure and chemical bonding at the Pt-electrolyte interface. Ab initio multiple-scattering calculations using the FEFF8 code and complementary extended x-ray absorption fine structure (EXAFS) results indicate that the commonly observed large increase of the white-line at high electrochemical potentials on PEMFC cathodes originates from platinum oxide formation, whereas previously proposed chemisorbed oxygen-containing species merely give rise to subtle spectral changes.

Friebel, Daniel

2011-08-24T23:59:59.000Z

344

Lunar X-ray fluorescence observations by the Chandrayaan-1 X-ray Spectrometer (C1XS): Results from the nearside southern highlands  

E-Print Network (OSTI)

Lunar X-ray fluorescence observations by the Chandrayaan-1 X-ray Spectrometer (C1XS): Results from Spectroscopy a b s t r a c t The Chandrayaan-1 X-ray Spectrometer (C1XS) flown on-board the first Indian lunar mission Chan- drayaan-1, measured X-ray fluorescence spectra during several episodes of solar flares

Wieczorek, Mark

345

Argonne CNM: X-Ray Microscopy Capabilities  

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

X-Ray Microscopy Facilities X-Ray Microscopy Facilities The Hard X-Ray Nanoprobe (HXN) facility provides scanning fluorescence, scanning diffraction, and full-field transmission and tomographic imaging capabilities with a spatial resolution of 30 nm over a spectral range of 6-12 keV. Modes of Operation Full-Field Transmission Imaging and Nanotomography X-ray transmission imaging uses both the absorption and phase shift of the X-ray beam by the sample as contrast mechanisms. Absorption contrast is used to map the sample density. Elemental constituents can be located by using differential edge contrast in this mode. Phase contrast can be highly sensitive to edges and interfaces even when the X-ray absorption is weak. These contrast mechanisms are exploited to image samples rapidly in full-field transmission mode under various environmental conditions, or combined with nanotomography methods to study the three-dimensional structure of complex and amorphous nanomaterials with the HXN.

346

THE X-RAY BINARY POPULATION IN M33. II. X-RAY SPECTRA AND VARIABILITY H.-J. Grimm, J. McDowell, A. Zezas, D.-W. Kim, and G. Fabbiano  

E-Print Network (OSTI)

THE X-RAY BINARY POPULATION IN M33. II. X-RAY SPECTRA AND VARIABILITY H.-J. Grimm, J. McDowell, A the X-ray spectra and X-ray spectral variability of compact X-ray sources for 3 Chandra observations observations shows that X-ray absorption values are consistent with Galactic X-ray binaries and most sources

Kim, Dong-Woo

347

13 - X-ray and Neutron Scattering  

Science Journals Connector (OSTI)

Abstract This chapter describes the use of neutrons and X-rays as probes in the study of structural and dynamic properties of metallic materials. Crystalline materials are characterized by their diffraction peaks related to their average crystallographic structure. In real crystals, locally displaced atoms and chemically (or isotopically for neutrons) different species may lead not only to changes of peak shapes and positions, but also to additional (diffuse) scattering between Bragg peak, including scattering around the primary beam (small-angle scattering). All these features can be used to extract information about the state of a sample, its compositional and structural variations on a scale depending on the scattering, in static and time-resolved kinetic studies. Energy-resolved scattering also offers an insight into solid-state dynamics on a microscopic scale. Some of the most important methods will be described and illustrated by instructive examples. The presentation offers a combined view of neutron and X-ray scattering, with the necessary simplifications dictated by space limitations. The special properties of thermal neutrons and of hard X-rays (now widely available at synchrotron radiation sources), their mutual combination, and combinations with other methods, in particular electron microscopy, offer ample opportunity to better understand and control materials properties. After a brief introduction to scattering from real crystals and some general ideas about long-range strains and Bragg peaks, the vicinity of Bragg peaks (displacement scattering at large scattering angles), the scattering far away from Bragg peaks (chemical heterogeneities, short-range order), and, in greater detail, small-angle scattering (which is not sensitive to the extent of crystallinity, but to nanoscale variations of chemical composition and of magnetization, precipitation) will be described, along with classical and more recent applications related to short-range ordering and precipitation in bulk and nanostructured alloys. Some other fields are only briefly addressed (grazing-incidence studies of surfaces, radiography, absorption spectroscopies, coherent X-rays). The final section offers some information on the influence of defects on lattice dynamics and on (slow) diffusive motion in materials.

Gernot Kostorz

2014-01-01T23:59:59.000Z

348

Laser Locking with Doppler-free Saturated Absorption Spectroscopy  

E-Print Network (OSTI)

there are many ways to stabilize the frequency of a laser, atomic absorption lines are particularly accurate are made, it becomes possible to resolve the saturated absorption lines that correspond to specific atomic absorption spectroscopy. This affects the number of atoms in the ground state and excited state

Novikova, Irina

349

Validity of automated x-ray photoelectron spectroscopy algorithm to determine the amount of substance and the depth distribution of atoms  

Science Journals Connector (OSTI)

The author reports a systematic study of the range of validity of a previously developed algorithm for automated x-ray photoelectron spectroscopy analysis which takes into account the variation in both peak intensity and the intensity in the background of inelastically scattered electrons. This test was done by first simulating spectra for the Au4d peak with gold atoms distributed in the form of a wide range of nanostructures which includes overlayers with varying thickness a 5?Å layer of atoms buried at varying depths and a substrate covered with an overlayer of varying thickness. Next the algorithm was applied to analyze these spectra. The algorithm determines the number of atoms within the outermost 3 ? of the surface. This amount of substance is denoted AOS 3 ? (where ?   is the electron inelastic mean free path). In general the determined AOS 3 ? is found to be accurate to within ?10–20% depending on the depth distribution of the atoms. The algorithm also determines a characteristic length L which was found to give unambiguous information on the depth distribution of the atoms for practically all studied cases. A set of rules for this parameter which relates the value of L to the depths where the atoms are distributed was tested and these rules were found to be generally valid with only a few exceptions. The results were found to be rather independent of the spectral energy range (from 20 to 40?eV below the peak energy) used in the analysis.

Sven Tougaard

2013-01-01T23:59:59.000Z

350

Water adsorption, solvation and deliquescence of alkali halide thin films on SiO2 studied by ambient pressure X-ray photoelectron spectroscopy  

SciTech Connect

The adsorption of water on KBr thin films evaporated onto SiO2 was investigated as a function of relative humidity (RH) by ambient pressure X-ray photoelectron spectroscopy. At 30percent RH adsorbed water reaches a coverage of approximately one monolayer. As the humidity continues to increase, the coverage of water remains constant or increases very slowly until 60percent RH, followed by a rapid increase up to 100percent RH. At low RH a significant number of the Br atoms are lost due to irradiation damage. With increasing humidity solvation increases ion mobility and gives rise to a partial recovery of the Br/K ratio. Above 60percent RH the increase of the Br/K ratio accelerates. Above the deliquescence point (85percent RH), the thickness of the water layer continues to increase and reaches more than three layers near saturation. The enhancement of the Br/K ratio at this stage is roughly a factor 2.3 on a 0.5 nm KBr film, indicating a strong preferential segregation of Br ions to the surface of the thin saline solution on SiO2.

Arima, Kenta; Jiang, Peng; Deng, Xingyi; Bluhm, Henrik; Salmeron, Miquel

2010-03-31T23:59:59.000Z

351

Design of an ultrahigh vacuum transfer mechanism to interconnect an oxide molecular beam epitaxy growth chamber and an x-ray photoemission spectroscopy analysis system  

SciTech Connect

We designed a mechanism and the accompanying sample holders to transfer between a VEECO 930 oxide molecular beam epitaxy (MBE) and a PHI Versa Probe X-ray photoemission spectroscopy (XPS) chamber within a multiple station growth, processing, and analysis system through ultrahigh vacuum (UHV). The mechanism consists of four parts: (1) a platen compatible with the MBE growth stage, (2) a platen compatible with the XPS analysis stage, (3) a sample coupon that is transferred between the two platens, and (4) the accompanying UHV transfer line. The mechanism offers a robust design that enables transfer back and forth between the growth chamber and the analysis chamber, and yet is flexible enough to allow transfer between standard sample holders for thin film growth and masked sample holders for making electrical contacts and Schottky junctions, all without breaking vacuum. We used this mechanism to transfer a barium strontium titanate thin film into the XPS analysis chamber and performed XPS measurements before and after exposing the sample to the air. After air exposure, a thin overlayer of carbon was found to form and a significant shift ({approx}1 eV) in the core level binding energies was observed.

Rutkowski, M. M.; Zeng Zhaoquan [Department of Physics, Ohio State University, Columbus, Ohio 43210 (United States); McNicholas, K. M. [Department of Electrical and Computer Engineering, Ohio State University, Columbus, Ohio 43210 (United States); Brillson, L. J. [Department of Physics, Ohio State University, Columbus, Ohio 43210 (United States); Department of Electrical and Computer Engineering, Ohio State University, Columbus, Ohio 43210 (United States)

2013-06-15T23:59:59.000Z

352

Kinetics of the sulfur oxidation on palladium: A combined in situ x-ray photoelectron spectroscopy and density-functional study  

SciTech Connect

We studied the reaction kinetics of sulfur oxidation on the Pd(100) surface by in situ high resolution x-ray photoelectron spectroscopy and ab initio density functional calculations. Isothermal oxidation experiments were performed between 400 and 500 K for small amounts ({approx}0.02 ML) of preadsorbed sulfur, with oxygen in large excess. The main stable reaction intermediate found on the surface is SO{sub 4}, with SO{sub 2} and SO{sub 3} being only present in minor amounts. Density-functional calculations depict a reaction energy profile, which explains the sequential formation of SO{sub 2}, SO{sub 3}, and eventually SO{sub 4}, also highlighting that the in-plane formation of SO from S and O adatoms is the rate limiting step. From the experiments we determined the activation energy of the rate limiting step to be 85 {+-} 6 kJ mol{sup -1} by Arrhenius analysis, matching the calculated endothermicity of the SO formation.

Gotterbarm, Karin; Hoefert, Oliver; Lorenz, Michael P. A.; Streber, Regine; Papp, Christian [Lehrstuhl fuer Physikalische Chemie II, Universitaet Erlangen-Nuernberg, Egerlandstr. 3, 91058 Erlangen (Germany); Luckas, Nicola; Vines, Francesc [Lehrstuhl fuer Theoretische Chemie, Universitaet Erlangen-Nuernberg, Egerlandstr. 3, 91058 Erlangen (Germany); Steinrueck, Hans-Peter [Lehrstuhl fuer Physikalische Chemie II, Universitaet Erlangen-Nuernberg, Egerlandstr. 3, 91058 Erlangen (Germany); Erlangen Catalysis Resource Center (ECRC), Universitaet Erlangen-Nuernberg, Egerlandstr. 3, 91058 Erlangen (Germany); Interdisciplinary Center for Interface Controlled Processes, Egerlandstr. 3, 91058 Erlangen (Germany); Goerling, Andreas [Lehrstuhl fuer Theoretische Chemie, Universitaet Erlangen-Nuernberg, Egerlandstr. 3, 91058 Erlangen (Germany); Interdisciplinary Center for Interface Controlled Processes, Egerlandstr. 3, 91058 Erlangen (Germany)

2012-03-07T23:59:59.000Z

353

X-ray laser  

DOE Patents (OSTI)

An X-ray laser (10) that lases between the K edges of carbon and oxygen, i.e. between 44 and 23 Angstroms, is provided. The laser comprises a silicon (12) and dysprosium (14) foil combination (16) that is driven by two beams (18, 20) of intense line focused (22, 24) optical laser radiation. Ground state nickel-like dysprosium ions (34) are resonantly photo-pumped to their upper X-ray laser state by line emission from hydrogen-like silicon ions (32). The novel X-ray laser should prove especially useful for the microscopy of biological specimens.

Nilsen, Joseph (Livermore, CA)

1991-01-01T23:59:59.000Z

354

X-Ray Generators  

Science Journals Connector (OSTI)

There are many types of X-ray generators sold commercially. The following are some of ... that should be considered when selecting a particular generator for a particular purpose. All the companies listed below s...

Reuben Rudman

1972-01-01T23:59:59.000Z

355

Optimization of the Configuration of Pixilated Detectors Based on the Shannon-Nyquist Theory for the X-Ray Spectroscopy of Hot Tokamak Plasmas  

SciTech Connect

This paper describes an optimization of the detector configuration, based on the Shannon-Nyquist theory, for two major x-ray diagnostic systems on tokamaks and stellarators: x-ray imaging crystal spectrometers and x-ray pinhole cameras. Typically, the spectral data recorded with pixilated detectors are oversampled, meaning that the same spectral information could be obtained using fewer pixels. Using experimental data from Alcator C-Mod, we quantify the degree of oversampling and propose alternate uses for the redundant pixels for additional diagnostic applications.

E. Wang, P. Beiersdorfer, M. Bitter, L.F. Delgado-Aprico, K.W. Hill and N. Pablant

2012-06-13T23:59:59.000Z

356

Optimization of the Configuration of Pixilated Detectors Based on the Sgabbib-Nyquist Theory for the X-ray Spectroscopy of Hot Tokamak Plasmas  

SciTech Connect

This paper describes an optimization of the detector configuration, based on the Shannon-Nyquist theory, for two major x-ray diagnostic systems on tokamaks and stellarators: x-ray imaging crystal spectrometers and x-ray pinhole cameras. Typically, the spectral data recorded with pixilated detectors are oversampled, meaning that the same spectral information could be obtained using fewer pixels. Using experimental data from Alcator C-Mod, we quantify the degree of oversampling and propose alternate uses for the redundant pixels for additional diagnostic applications.

: E. Wang, P. Beiersdorfer, M. Bitter, L.F. Delgado-Apricio, K.W. Hill and N. Pablant

2012-08-09T23:59:59.000Z

357

X-ray Emission from Massive StarsX-ray Emission from Massive Stars David CohenDavid Cohen  

E-Print Network (OSTI)

X-ray Emission from Massive StarsX-ray Emission from Massive Stars David CohenDavid Cohen/s)Velocity (km/s) #12;absorption emission emission occulted emission emission UV telescope side side front back #12;absorption emission emission occulted emission emission UV telescope side side front back #12;The

Cohen, David

358

Line X-ray emission from Al targets irradiated by high-intensity, variable-length laser pulses  

E-Print Network (OSTI)

Line X-ray emission from Al targets irradiated by high-intensity, variable-length laser pulses J; the scaling rules for the conversion efficiency of the laser radiation into the line X-ray emission are discussed. Keywords: Laser-produced plasma; Line X-ray emission; X-ray sources; X-ray spectroscopy 1

Limpouch, Jiri

359

E-Print Network 3.0 - absorption spectroscopy techniques Sample...  

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

A partial sampling of these techniques includes: Absorption spectroscopy Atomic absorption... 109 3.4 Spectroscopic Sensors Spectroscopy is the scientific study of...

360

X-ray spectral diagnostics of neon photoionization experiments on the Z-machine  

E-Print Network (OSTI)

X-ray spectral diagnostics of neon photoionization experiments on the Z-machine David H. Cohen on an initial spectroscopic study of low-density, x-ray photoionized neon with x-ray spectroscopy plasma, and to explore issues related to the rapid x-ray photoionization of relatively cold, low

Cohen, David

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


361

X-ray absorption study of the O 2p hole concentration dependence on O stoichiometry in YBa/sub 2/Cu/sub 3/O/sub x/  

SciTech Connect

A detailed x-ray absorption study of the oxygen K edge of YBa/sub 2/Cu/sub 3/O/sub x/ is presented. A preedge peak is observed for all samples with xgreater than or equal to6.4 which we argue to be due to holes in the O 2p band. By comparison to Li/sub x/Ni/sub (1-//sub x//sub )/O the x dependence of the number of O 2p holes in YBa/sub 2/Cu/sub 3/O/sub x/ is determined.

Kuiper, P.; Kruizinga, G.; Ghijsen, J.; Grioni, M.; Weijs, P.J.W.; de Groot, F.M.F.; Sawatzky, G.A.; Verweij, H.; Feiner, L.F.; Petersen, H.; and others

1988-10-01T23:59:59.000Z

362

Pressure-induced phase transition of Fe{sub 2}TiO{sub 4}: X-ray diffraction and Moessbauer spectroscopy  

SciTech Connect

X-ray diffraction and Moessbauer spectroscopy were employed to investigate structural stability of Fe{sub 2}TiO{sub 4} under high pressure. Measurements were performed up to about 24 GPa at room temperature using diamond anvil cell. Experimental results demonstrate that Fe{sub 2}TiO{sub 4} undergoes a series of phase transitions from cubic (Fd3-bar m) to tetragonal (I4{sub 1}/amd) at 8.7 GPa, and then to orthorhombic structure (Cmcm) at 16.0 GPa. The high-pressure phase (Cmcm) of Fe{sub 2}TiO{sub 4} is kept on decompression to ambient pressure. In all polymorphs of Fe{sub 2}TiO{sub 4}, iron cations present a high-spin ferrous property without electric charge exchange with titanium cations at high pressure supported by Moessbauer evidences. - Graphical abstract: A series of phase transition of Fe{sub 2}TiO{sub 4} occurs from cubic (a) to tetragonal (b and c) then to orthorhombic phase (d-f) at high pressure. Highlights: Black-Right-Pointing-Pointer High pressure behaviors of Fe{sub 2}TiO{sub 4} were investigated. Black-Right-Pointing-Pointer Phase transitions were observed from cubic to tetragonal and then to orthorhombic. Black-Right-Pointing-Pointer Orthorhombic phase can be kept on decompression. Black-Right-Pointing-Pointer In all polymorphs of Fe{sub 2}TiO{sub 4}, iron ions are ferrous with high-spin state.

Wu Ye [Key Laboratory of Orogenic Belts and Crustal Evolution, MOE, Peking University, Beijing 100871 (China); School of Earth and Space Sciences, Peking University, Beijing 100871 (China); Wu Xiang, E-mail: xiang.wu@pku.edu.cn [Key Laboratory of Orogenic Belts and Crustal Evolution, MOE, Peking University, Beijing 100871 (China); School of Earth and Space Sciences, Peking University, Beijing 100871 (China); Qin Shan [Key Laboratory of Orogenic Belts and Crustal Evolution, MOE, Peking University, Beijing 100871 (China); School of Earth and Space Sciences, Peking University, Beijing 100871 (China)

2012-01-15T23:59:59.000Z

363

Influence of electron irradiation and heating on secondary electron yields from non-evaporable getter films observed with in situ x-ray photoelectron spectroscopy  

SciTech Connect

Nonevaporable getter (NEG) film has been used for the beam ducts of particle accelerators as a pump having a large area. NEG film has been considered to have a low outgas rate induced by energetic particle irradiation and a low secondary electron yield (SEY). In this article, we focused on SEY measurements and in situ surface characterization of four NEG film samples using x-ray photoelectron spectroscopy (XPS). The NEG samples were TiZrV thin films deposited by magnetron sputtering at 100 or 300 deg. C on stainless steel. In addition, NEG samples saturated by CO gas exposure were prepared. SEY and XPS measurements of the surfaces of NEG samples were carried out under the conditions of as received, after electron beam irradiation, and after heating at 200 deg. C for 24 h. The maximum SEY values of the primary electron energy dependence, {delta}{sub max}, of all NEG samples decreased to around 1 by electron beam irradiation owing to a change in the carbon impurities, such as carbon oxide, carbon hydroxide, and hydrocarbon, to graphite state (graphitization) during the irradiation. After heating, {delta}{sub max} values of the NEG samples without CO gas exposure were also around 1 owing to the carbonization of Ti, Zr, and V. The {delta}{sub max}{approx_equal}1 was remarkably lower than that of copper baked under the same conditions. However, in saturated NEG samples, metal carbides were not produced to a significant extent by heating, and the {delta}{sub max} values did not decrease, showing values of 1.5-1.7.

Nishiwaki, Michiru; Kato, Shigeki [High Energy Accelerator Research Organization (KEK), 1-1 Oho, Tsukuba, Ibaraki 305-0801 (Japan); High Energy Accelerator Research Organization (KEK), 1-1 Oho, Tsukuba, Ibaraki 305-0801 (Japan) and Department of Accelerator Science, The Graduate University for Advanced Studies, 1-1 Oho, Tsukuba, Ibaraki 305-0801 (Japan)

2007-07-15T23:59:59.000Z

364

Direct and quantitative absorptive spectroscopy of nanowires  

E-Print Network (OSTI)

Photonic nanostructures exhibit unique optical properties that are attractive in many different applications. However, measuring the optical properties of individual nanostructures, in particular the absorptive properties, ...

Tong, Jonathan Kien-Kwok

2012-01-01T23:59:59.000Z

365

Introduction to Neutron and X-Ray Scattering  

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

Scattering Studies of Thin Scattering Studies of Thin Polymer Films Introduction to Neutron and X-Ray Scattering Sunil K. Sinha UCSD/LANL Acknowledgements: Prof. R.Pynn( Indiana U.) Prof. M.Tolan (U. Dortmund) Wilhelm Conrad Röntgen 1845-1923 1895: Discovery of X-Rays 1901 W. C. Röntgen in Physics for the discovery of x-rays. 1914 M. von Laue in Physics for x-ray diffraction from crystals. 1915 W. H. Bragg and W. L. Bragg in Physics for crystal structure determination. 1917 C. G. Barkla in Physics for characteristic radiation of elements. 1924 K. M. G. Siegbahn in Physics for x-ray spectroscopy. 1927 A. H. Compton in Physics for scattering of x-rays by electrons. 1936 P. Debye in Chemistry for diffraction of x-rays and electrons in gases.

366

X-ray beam finder  

DOE Patents (OSTI)

An X-ray beam finder for locating a focal spot of an X-ray tube includes a mass of X-ray opaque material having first and second axially-aligned, parallel-opposed faces connected by a plurality of substantially identical parallel holes perpendicular to the faces and a film holder for holding X-ray sensitive film tightly against one face while the other face is placed in contact with the window of an X-ray head.

Gilbert, H.W.

1983-06-16T23:59:59.000Z

367

Development of soft X-ray polarized light beamline on Indus-2 synchrotron radiation source  

SciTech Connect

This article describes the development of a soft x-ray beamline on a bending magnet source of Indus-2 storage ring (2.5 GeV) and some preliminary results of x-ray absorption spectroscopy (XAS) measurements using the same. The beamline layout is based on a spherical grating monochromator. The beamline is able to accept synchrotron radiation from the bending magnet port BL-1 of the Indus-2 ring with a wide solid angle. The large horizontal and vertical angular acceptance contributes to high photon flux and selective polarization respectively. The complete beamline is tested for ultrahigh vacuum (UHV) ? 10{sup ?10} mbar. First absorption spectrum was obtained on HOPG graphite foil. Our performance test indicates that modest resolving power has been achieved with adequate photon flux to carry out various absorption experiments.

Phase, D. M., E-mail: mgupta@csr.res.in; Gupta, Mukul, E-mail: mgupta@csr.res.in; Potdar, S., E-mail: mgupta@csr.res.in; Behera, L., E-mail: mgupta@csr.res.in; Sah, R., E-mail: mgupta@csr.res.in; Gupta, Ajay, E-mail: mgupta@csr.res.in [UGC-DAE Consortium for Scientific Research, University Campus, Khandwa Road, Indore, 452001 (India)

2014-04-24T23:59:59.000Z

368

The Constellation X-ray mission  

Science Journals Connector (OSTI)

The Constellation-X mission is a large collecting area X-ray facility, emphasizing observations at high spectral resolution (E/?E?300–3000) while covering a broad energy band (0.25–40 keV). By increasing the telescope aperture and utilizing efficient spectrometers the mission will achieve a factor of 100 increased sensitivity over current high-resolution X-ray spectroscopy missions. The use of focussing optics across the 10–40 keV band will provide a similar factor of 100 increased sensitivity in this band. Key technologies under development for the mission include lightweight high throughput X-ray optics, multilayer coatings to enhance the hard X-ray performance of X-ray optics, micro-calorimeter spectrometer arrays with 2 eV resolution, low-power and low-weight CCD arrays, lightweight gratings and hard X-ray detectors. When observations commence towards the end of the next decade, Constellation-X will address many pressing questions concerning the extremes of gravity and the evolution of the Universe.

N.E White; H Tananbaum

1999-01-01T23:59:59.000Z

369

Multiplexed absorption tomography with calibration-free wavelength modulation spectroscopy  

SciTech Connect

We propose a multiplexed absorption tomography technique, which uses calibration-free wavelength modulation spectroscopy with tunable semiconductor lasers for the simultaneous imaging of temperature and species concentration in harsh combustion environments. Compared with the commonly used direct absorption spectroscopy (DAS) counterpart, the present variant enjoys better signal-to-noise ratios and requires no baseline fitting, a particularly desirable feature for high-pressure applications, where adjacent absorption features overlap and interfere severely. We present proof-of-concept numerical demonstrations of the technique using realistic phantom models of harsh combustion environments and prove that the proposed techniques outperform currently available tomography techniques based on DAS.

Cai, Weiwei; Kaminski, Clemens F., E-mail: cfk23@cam.ac.uk [Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge CB2 3RA (United Kingdom)

2014-04-14T23:59:59.000Z

370

X-ray Spectrometry  

Science Journals Connector (OSTI)

These provide excellent energy resolution for a wide range of X-ray energies, from the optical range up to several kiloelectronvolts. ... The Astro-E2 launched in 2005 was the first mission that contained a low-temperature microcalorimeter-based observatory, and three more low-temperature detector-based observatories are being developed (NeXT, Constellation-X, ZEUS). ...

Imre Szalóki; János Osán; René E. Van Grieken

2006-05-10T23:59:59.000Z

371

X-ray photoelectron spectroscopy and structural analysis of amorphous SiO{sub x}N{sub y} films deposited at low temperatures  

SciTech Connect

We establish, using a tetrahedral model, the bonding properties of amorphous silicon oxynitride (a-SiO{sub x}N{sub y}) films deposited at low temperatures (LTs) by electron-cyclotron resonance chemical-vapor deposition (ECRCVD) on several substrates and under various conditions of gas flows and total gas pressure in a dilute mixture of SiH{sub 4}+N{sub 2} in Ar. The atomic percentage of each tetrahedral unit incorporated in the film network is calculated from the deconvolution of the high-resolution x-ray photoelectron spectroscopy (XPS) spectra in the Si 2p{sub 3/2} region and corroborated by the results obtained from both survey scans and the high-resolution XPS spectra in the N 1s region. The Si{sub 3}N{sub 4} phase is the most important one and the only bonding unit which is incorporated in all our LT ECRCVD SiO{sub x}N{sub y} films. The incorporation of all the other component tetrahedrons depends strongly on growth conditions. The threshold values of the N/Si atomic ratio for which intrinsic defects, such as Si-Si bonds, are not incorporated in the network depend on the O/Si ratio incorporated in the films, mainly due to the competition between oxygen and nitrogen atoms in their reaction with silicon dangling bonds. The effect of the total gas pressure on the atomic percentages of the oxidation states present in the LT ECRCVD SiO{sub x}N{sub y} films is qualitatively similar to the effect of the ion bombarding energy or the plasma density. O-N bonds are present only in samples having high amount of oxygen and nitrogen in their networks. For these films, our results show unambiguously the presence of the N-Si{sub 2}O tetrahedron and suggest that N-Si{sub 3-{nu}}O{sub {nu}} tetrahedrons with {nu}{>=}2 are not incorporated in their networks. A correlation is observed between the N-Si{sub 2}O and the Si-O{sub 3}(ON) tetrahedrons whose component peak is localized at (104.0{+-}0.2) eV in the Si 2p{sub 3/2} region of the XPS data, which suggests that both bonding units coexist in these films as some sort of complex bonding configuration.

Cova, P.; Poulin, S.; Masut, R.A. [Departmento de Fisica, Laboratorio de Simulacion de Dispositivos Semiconductores, Universidad de Oriente, Apartado 124, Cumana 6101, Sucre (Venezuela); Regroupement Quebecois sur les Materiaux de Pointe (RQMP) and Departement de Genie Physique, Ecole Polytechnique, C.P. 6079, succ. Centre-ville, Montreal, Quebec H3C 3A7 (Canada)

2005-11-01T23:59:59.000Z

372

Laser wakefield generated X-ray probe for femtosecond time-resolved measurements of ionization states of warm dense aluminum  

SciTech Connect

We have developed a laser wakefield generated X-ray probe to directly measure the temporal evolution of the ionization states in warm dense aluminum by means of absorption spectroscopy. As a promising alternative to the free electron excited X-ray sources, Betatron X-ray radiation, with femtosecond pulse duration, provides a new technique to diagnose femtosecond to picosecond transitions in the atomic structure. The X-ray probe system consists of an adjustable Kirkpatrick-Baez (KB) microscope for focusing the Betatron emission to a small probe spot on the sample being measured, and a flat Potassium Acid Phthalate Bragg crystal spectrometer to measure the transmitted X-ray spectrum in the region of the aluminum K-edge absorption lines. An X-ray focal spot size of around 50 ?m was achieved after reflection from the platinum-coated 10-cm-long KB microscope mirrors. Shot to shot positioning stability of the Betatron radiation was measured resulting in an rms shot to shot variation in spatial pointing on the sample of 16 ?m. The entire probe setup had a spectral resolution of ?1.5 eV, a detection bandwidth of ?24 eV, and an overall photon throughput efficiency of the order of 10{sup ?5}. Approximately 10 photons were detected by the X-ray CCD per laser shot within the spectrally resolved detection band. Thus, it is expected that hundreds of shots will be required per absorption spectrum to clearly observe the K-shell absorption features expected from the ionization states of the warm dense aluminum.

Mo, M. Z.; Chen, Z.; Tsui, Y. Y.; Fedosejevs, R. [Department of Electrical and Computer Engineering, University of Alberta, Edmonton, Alberta T6G 2V4 (Canada)] [Department of Electrical and Computer Engineering, University of Alberta, Edmonton, Alberta T6G 2V4 (Canada); Fourmaux, S.; Saraf, A.; Otani, K.; Kieffer, J. C. [INRS-EMT, Université du Québec, 1650 Lionel Boulet, Varennes, Québec J3X 1S2 (Canada)] [INRS-EMT, Université du Québec, 1650 Lionel Boulet, Varennes, Québec J3X 1S2 (Canada); Ng, A. [Department of Physics and Astronomy, University of British Columbia, British Columbia V6T 1Z1 (Canada)] [Department of Physics and Astronomy, University of British Columbia, British Columbia V6T 1Z1 (Canada)

2013-12-15T23:59:59.000Z

373

Inner-Shell Excitation Spectroscopy of Fused-Ring Aromatic Molecules by Electron Energy Loss and X-ray Raman Techniques  

E-Print Network (OSTI)

Versity, Hamilton, ON, L8S 4M1, Canada, Department of Chemistry, Utrecht UniVersity, 3584 CA Utrecht, The Netherlands, Schlumberger-Doll Research, Ridgefield, Connecticut 06877, Department of Applied Science, Uni that could be applied without modifying the hydrocarbon material. Inelastic X-ray Raman scattering (XRS)2

Hitchcock, Adam P.

374

USE OF ZEEMAN ATOMIC ABSORPTION SPECTROSCOPY FOR THE MEASUREMENT OF MERCURY IN OIL SHALE GASES  

E-Print Network (OSTI)

Isotope Zeeman Atomic Absorption; A new approach to chemical6782 Use of Zeeman Atomic Absorption Spectroscopy for theb:l r I USE OF ZEEMAN ATOMIC ABSORPTION SPECTROSCOPY FOR THE

Girvin, D.G.

2011-01-01T23:59:59.000Z

375

Absolute absorption spectroscopy based on molecule interferometry  

E-Print Network (OSTI)

We propose a new method to measure the absolute photon absorption cross section of neutral molecules in a molecular beam. It is independent of our knowledge of the particle beam density, nor does it rely on photo-induced fragmentation or ionization. The method is based on resolving the recoil resulting from photon absorption by means of near-field matter-wave interference, and it thus applies even to very dilute beams with low optical densities. Our discussion includes the possibility of internal state conversion as well as fluorescence. We assess the influence of various experimental uncertainties and show that the measurement of absolute absorption cross sections is conceivable with high precision and using existing technologies.

Stefan Nimmrichter; Klaus Hornberger; Hendrik Ulbricht; Markus Arndt

2008-11-07T23:59:59.000Z

376

Chemical reactions at Cu/ZnS(001) and In/ZnS(001) heterojunctions: A comparison of photoelectron and S L{sub 2,3} x-ray emission spectroscopy  

SciTech Connect

Occurrence and extent of chemical reactions at Cu/ZnS(001) and In/ZnS(001) heterojunctions have been investigated by S L{sub 2,3} x-ray emission spectroscopy as well as photoelectron spectroscopy. With the formation of metal-sulfur bonds, spectral features originating from shallow metal d core levels (Zn 3d, In 4d) or valence states (Cu 3d)) may appear in the S L{sub 2,3} emission spectra. Thus the x-ray emission spectroscopy was employed to detect chemical reactions at the heterojunctions, together with conventional photoelectron spectroscopy. Considerable reactions at the Cu/ZnS(001) interface are more clearly indicated in the S L emission spectrum than in the Cu 2p{sub 3sol2} or S 2p core level spectra, whereas relatively confined reactions at the In/ZnS(001) interface can only be probed in the In 3d{sub 5sol2} core level spectra. The partial densities of states calculated for a reference CuInS{sub 2} on the basis of density functional theory agree well with features occurring in its S L{sub 2,3} emission spectrum.

Zhang, L.; Wett, D.; Schulze, D.; Szargan, R.; Nagel, M.; Peisert, H.; Chasse, T. [Institut fuer Physikalische und Theoretische Chemie, Universitaet Tuebingen, Auf der Morgenstelle 8, 72076 Tuebingen (Germany); Wilhelm-Ostwald-Institut fuer Physikalische und Theoretische Chemie, Universitaet Leipzig, Linnestrasse 2, 04103 Leipzig (Germany); Wilhelm-Ostwald-Institut fuer Physikalische und Theoretische Chemie, Universitaet Leipzig, Linnestrasse 2, 04103 Leipzig (Germany); Institut fuer Physikalische und Theoretische Chemie, Universitaet Tuebingen, Auf der Morgenstelle 8, 72076 Tuebingen (Germany)

2005-01-03T23:59:59.000Z

377

Dissimilar behavior of technetium and rhenium in borosilicate waste glass as determined by X-ray absorption spectroscopy  

E-Print Network (OSTI)

N. R. ; LaMont, P. E. "Hanford immobilized low-activity tankstudies with simulated Hanford low-activity waste," PNNL-Darab, J. G. ; Smith, H. D. "Hanford tank waste simulants

Lukens, Wayne W.; McKeown, David A.; Buechele, Andrew C.; Muller, Isabelle S.; Shuh, David K.; Pegg, Ian L.

2006-01-01T23:59:59.000Z

378

RELAXATION SHIFTS, LINE SHAPES AND SATELLITES IN THE X-RAY AND ABSORPTION SPECTROSCOPY OF ADSORBED SPECIES (*)  

E-Print Network (OSTI)

OF ADSORBED SPECIES (*) B. GUMHALTER (**) Department of Mathematics, Imperial College, London SW 7, England spectra of adsorbate electron levels are presented. The formalism of the surface response function is developed for treating the nonbonding surface induced effects in adsorbate electron states. It is shown

Paris-Sud XI, Université de

379

On the importance of nuclear quantum motions in near edge x-ray absorption fine structure (NEXAFS) spectroscopy of molecules  

SciTech Connect

We report the effects of sampling nuclear quantum motion with path integral molecular dynamics (PIMD) on calculations of the nitrogen K-edge spectra of two isolated organic molecules. S-triazine, a prototypical aromatic molecule occupying primarily its vibrational ground state at room temperature, exhibits substantially improved spectral agreement when nuclear quantum effects are included via PIMD, as compared to the spectra obtained from either a single fixed-nuclei based calculation or from a series of configurations extracted from a classical molecular dynamics trajectory. Nuclear quantum dynamics can accurately explain the intrinsic broadening of certain features. Glycine, the simplest amino acid, is problematic due to large spectral variations associated with multiple energetically accessible conformations at the experimental temperature. This work highlights the sensitivity of NEXAFS to quantum nuclear motions in molecules, and the necessity of accurately sampling such quantum motion when simulating their NEXAFS spectra.

Schwartz, Craig P.; Uejio, Janel S.; Saykally, Richard J.; Prendergast, David

2009-02-26T23:59:59.000Z

380

Real-time x-ray absorption spectroscopy of uranium, iron, and manganese in contaminated sediments during bioreduction  

E-Print Network (OSTI)

National Laboratory, Berkeley, California 94720 University of Chicago, Chicago, Illinois 60637 Savannah River

Tokunaga, T.K.

2008-01-01T23:59:59.000Z

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


381

USE OF MICRO X-RAY ABSORPTION SPECTROSCOPY AND DIFFRACTION TO DELINEATE Cr(VI) SPECIATION IN COPR  

E-Print Network (OSTI)

Ca 2 FeAlO 5 Periclase MgO Brucite Mg(OH) 2 Calcite CaCO 3Fe +3 ) 2 O 5 00-007-0239> Brucite - Mg(OH) 2 00-008-0458>

CHRYSOCHOOU, M.

2010-01-01T23:59:59.000Z

382

Real-time x-ray absorption spectroscopy of uranium, iron, and manganese in contaminated sediments during bioreduction  

E-Print Network (OSTI)

ferric iron in aquatic sediments. Applied and Environmentalin evaporation basin sediments. Geochimica Cosmochimica Actaof uranium-contaminated subsurface sediments. Environmental

Tokunaga, T.K.

2008-01-01T23:59:59.000Z

383

Polarized Range-Extended X-Ray Absorption Spectroscopy of Oriented Photosystem Ii Membranes in the S (1) State  

SciTech Connect

Detailed information about the orientation of particular Mn-Mn and Mn-Ca vectors in the oxygen evolving complex (OEC) of the Photosystem II in the S{sub 1} state provide a critical starting point for the analysis of the structural changes in the OEC along the catalytic S{sub i}-state cycle. The method of polarized range-extended EXAFS is an important technical development, that allows: (i) resolution of the 2.7 {angstrom} and 2.8 {angstrom} Mn-Mn interactions; (ii) resolution of 3.2 {angstrom} Mn-Mn and 3.4 {angstrom} Mn-Ca; (iii) determination of 2.7 {angstrom}, 2.8 {angstrom}, 3.2 {angstrom} Mn-Mn and 3.4 {angstrom} Mn-Ca vectors orientation relative to the membrane normal.

Pushkar, Y.; Yano, J.; Glatzel, P.; Messinger, J.; Lewis, A.; Sauer, K.; Bergmann, U.; Yachandra, V.K.

2009-06-05T23:59:59.000Z

384

Characterization of selective binding of alkali cations with carboxylate by x-ray absorption spectroscopy of liquid microjets  

E-Print Network (OSTI)

sodium acetate, and lithium acetate revealing distinctpotassium, and lithium with acetate and formate anions informate and acetate solutions containing lithium, sodium,

Uejio, Janel S.

2008-01-01T23:59:59.000Z

385

USE OF MICRO X-RAY ABSORPTION SPECTROSCOPY AND DIFFRACTION TO DELINEATE Cr(VI) SPECIATION IN COPR  

E-Print Network (OSTI)

2006), Evaluation of Ettringite and Hydrocalumite FormationChristodoulatos C. , (2006b), Ettringite-Induced Heave inas previously noted. Finally, ettringite is theoretically a

CHRYSOCHOOU, M.

2010-01-01T23:59:59.000Z

386

X-Ray Absorption Spectroscopy of Plutonium Particles at the Rocky Flats US Nuclear Weapons Production Site  

Science Journals Connector (OSTI)

The Rocky Flats Environmental Technology Site (RFETS) was a...2. This information coupled with ultrafiltration studies was used to make the case for particle transport mechanisms as the basis of plutonium and ame...

Steven D. Conradson; David L. Clark; Christophe den Auwer…

2011-01-01T23:59:59.000Z

387

USE OF MICRO X-RAY ABSORPTION SPECTROSCOPY AND DIFFRACTION TO DELINEATE Cr(VI) SPECIATION IN COPR  

SciTech Connect

The speciation of Cr(VI) in Cromite Ore Processing Residue was investigated by means of bulk XRD, and a combination of micro-XRF, -XAS and -XRD at the Advanced Light Source (ALS), Berkeley, CA, U.S.A.. Bulk XRD yielded one group of phases that contained explicitly Cr(VI) in their structure, Calcium Aluminum Chromium Oxide Hydrates, accounting for 60% of the total Cr(VI). Micro-analyses at ALS yielded complimentary information, confirming that hydrogarnets and hydrotalcites, two mineral groups that can host Cr(VI) in their structure by substitution, were indeed Cr(VI) sinks. Chromatite (CaCrO4) was also identified by micro-XRD, which was not possible with bulk methods due to its low content. The acquisition of micro-XRF elemental maps enabled not only the identification of Cr(VI)-binding phases, but also the understanding of their location within the matrix. This information is invaluable when designing Cr(VI) treatment, to optimize release and availability for reduction.

CHRYSOCHOOU, M.; MOON, D. H.; FAKRA, S.; MARCUS, M.; DERMATAS, D.; CHRISTODOULATOS, C.

2010-06-22T23:59:59.000Z

388

APS 7-BM Beamline: X-Ray Resources  

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

Useful Websites Useful Websites X-Ray Interactions with Matter from CRXO at LBNL. Intuitive interface for x-ray transmission and reflectivity for a wide range of materials. X-Ray Data Booklet from LBNL. Slightly outdated in places, but many useful tables of edge energies, fluorescence lines, and crystal lattice spacings. NIST XCOM Database. Powerful database of photoelectric absorption, elastic scattering, and Compton scattering cross-sections for a wide range of materials. X-Ray Server. Maintained by Sergey Stepanov at GMCA at the APS, this website has several powerful calculators for simulating x-ray reflection and diffraction. Software X-Ray Oriented Programs (XOP). This program, written by scientists at the ESRF and APS, is widely used in the synchrotron research community.

389

Tunable X-ray source  

DOE Patents (OSTI)

A method for the production of X-ray bunches tunable in both time and energy level by generating multiple photon, X-ray, beams through the use of Thomson scattering. The method of the present invention simultaneously produces two X-ray pulses that are tunable in energy and/or time.

Boyce, James R. (Williamsburg, VA)

2011-02-08T23:59:59.000Z

390

Photon Sciences | Beamlines | IXS: Inelastic X-ray Scattering  

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

IXS: Inelastic X-ray Scattering IXS: Inelastic X-ray Scattering Poster | Fact Sheet | Preliminary Design Report Scientific Scope Many hot topics related to the high frequency dynamics of condensed matter require both a narrower and steeper resolution function and access to a broader dynamic range than what are currently available. This represents a sort of "no man's land" that falls right in the dynamic gap lying between the high frequency spectroscopies, such as inelastic x-ray scattering (IXS), and the low frequency ones. New IXS spectrometers with improved energy and momentum resolutions would be required to fill this gap. To achieve this goal, a new x-ray optics concept for both the monochromatization and energy analysis of x-rays will be implemented at the NSLS-II Inelastic X-ray Scattering beamline. This solution exploits the

391

Satellites in x-ray photoelectron spectroscopy of insulators. II. Multielectron excitations in LiF, NaF, and KF  

Science Journals Connector (OSTI)

The satellites appearing in the core regions of the x-ray photoelectron spectra of alkali fluorides have been investigated in order to obtain information about the distribution of interband transitions. The photoemission results are compared with some recent theoretical band-structure calculations. The differences in the relative intensities observed in the different core regions are ascribed to the presence of excitons in the spectra.

Marisa Scrocco

1985-07-15T23:59:59.000Z

392

Correlation between Charge State of Insulating NaCl Surfaces and Ionic Mobility Induced by Water Adsorption: A Combined Ambient Pressure X-ray Photoelectron Spectroscopy and Scanning Force Microscopy Study  

SciTech Connect

In situ ambient pressure X-ray photoelectron spectroscopy (APPES) and scanning force microscopy were used to characterize the surface discharge induced by water layers grown on (001) surfaces of sodium chloride single crystals. The APPES studies show that both kinetic energy (KE) and full width at half-maximum (FWHM) of the Na 2s and Cl 2p core level peaks, monitored as a function of relative humidity (RH), mimic surface conductivity curves measured using scanning force microscopy. The KE position and FWHM of the core level peaks therefore are directly related to the solvation and diffusion of ions at the NaCl(100) surface upon adsorption of water.

Verdaguer, Albert; Jose Segura, Juan; Fraxedas, Jordi; Bluhm, Hendrik; Salmeron, Miquel

2008-09-03T23:59:59.000Z

393

Effects of {pi}-stacking interactions on the near carbon K-edge x-ray absorption fine structure: A theoretical study of the ethylene pentamer and the phthalocyanine dimer  

SciTech Connect

X-ray absorption spectra have been determined for ethylene and free base phthalocyanine at the carbon K-edge with use of the complex polarization propagator method combined with Kohn-Sham density functional theory and the Coulomb attenuated method B3LYP exchange-correlation functional. Apart from isolated molecules, the study includes {pi}-stacked systems of the phthalocyanine dimer and the ethylene dimer, trimer, tetramer, and pentamer. For ethylene, {pi}-stacking involves a reduction in transition energy of the valence {pi}*-band by some 70 meV and large spectral changes (regarding also shape and intensity) of the Rydberg bands. For phthalocyanine, there are large spectral changes in the entire valence {pi}*-part of the spectrum.

Linares, Mathieu; Stafstroem, Sven; Norman, Patrick [Department of Physics, Chemistry and Biology, Linkoeping University, SE-581 83 Linkoeping (Sweden)

2009-03-14T23:59:59.000Z

394

A new spectrometer design for the x-ray spectroscopy of laser-produced plasmas with high (sub-ns) time resolution  

SciTech Connect

This paper describes a new type of x-ray crystal spectrometer, which can be used in combination with gated x-ray detectors to obtain spectra from laser-produced plasmas with a high (sub-ns) time resolution. The spectrometer consists of a convex, spherically bent crystal, which images individual spectral lines as perfectly straight lines across multiple, sequentially gated, strip detectors. Since the Bragg-reflected rays are divergent, the distance between detector and crystal is arbitrary, so that this distance can be appropriately chosen to optimize the experimental arrangement with respect to the detector parameters. The spectrometer concept was verified in proof-of-principle experiments by imaging the L?{sub 1}- and L?{sub 2}-lines of tungsten, at 9.6735 and 9.96150 keV, from a micro-focus x-ray tube with a tungsten target onto a two-dimensional pixilated Pilatus detector, using a convex, spherically bent Si-422 crystal with a radius of curvature of 500 mm.

Bitter, M., E-mail: bitter@pppl.gov; Hill, K. W.; Efthimion, P. C.; Delgado-Aparicio, L.; Pablant, N. [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States); Lu, Jian [Department of Engineering, Chongqing University, Chongqing 400044 (China); Beiersdorfer, P.; Chen, Hui [Physics Division, Lawrence Livermore National Laboratory, Livermore, California 94550 (United States)

2014-11-15T23:59:59.000Z

395

Molecular shock response of explosives: electronic absorption spectroscopy  

SciTech Connect

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.

Mcgrne, Shawn D [Los Alamos National Laboratory; Moore, David S [Los Alamos National Laboratory; Whitley, Von H [Los Alamos National Laboratory; Bolme, Cindy A [Los Alamos National Laboratory; Eakins, Daniel E [Los Alamos National Laboratory

2009-01-01T23:59:59.000Z

396

X-ray Spectrometry  

Science Journals Connector (OSTI)

The segmented STJ operated at total count rates of above 105 counts/s, and the best-achieved energy resolution of their single STJ was found to be 10 eV for X-ray energies below 1 keV. ... The Mo?Au TES, with an operating temperature of 230 mK, was developed for the Constellation-X mission and the energy resolution of the spectrometer is ?28 eV at 3.3 keV. ...

Imre Szalóki; Szabina B. Török; Jasna Injuk; René E. Van Grieken

2002-05-18T23:59:59.000Z

397

Temperature dependent electronic structure of Pr{sub 0.67}Sr{sub 0.33}MnO{sub 3} film probed by X-ray absorption near edge structure  

SciTech Connect

The Mn K edge X-ray absorption near edge structures (XANES) of Pr{sub 0.67}Sr{sub 0.33}MnO{sub 3} film (100 nm) on (001) LaAlO{sub 3} substrate was measured at different temperatures to probe the MnO{sub 6} octahedron distortion and corresponding electronic structure. The absorption of high temperature paramagnetic-insulator phase differed from that of the low temperature ferromagnetic-metal phase. The temperature-dependent absorption intensity of Mn K edge XANES was correlated with the relaxation of distorted MnO{sub 6} octahedron, which changed the crystal field acting on the Mn site and the related electronic structure and properties. At low temperature, the splitting of Mn majority e{sub g} orbitals decreased and the density of states above the Fermi level increased in the relaxed MnO{sub 6} octahedron, as reflected by a wider separation between two sub-peaks in the pre-edge XANES spectra.

Zhang, Bangmin [Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Department of Materials Science and Engineering, National University of Singapore, Singapore 117576 (Singapore); NUSNNI-Nanocore, National University of Singapore, Singapore 117411 (Singapore); Sun, Cheng-Jun, E-mail: cjsun@aps.anl.gov, E-mail: msecgm@nus.edu.sg; Heald, Steve M. [Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Chen, Jing-Sheng; Moog Chow, Gan, E-mail: cjsun@aps.anl.gov, E-mail: msecgm@nus.edu.sg [Department of Materials Science and Engineering, National University of Singapore, Singapore 117576 (Singapore); Venkatesan, T. [NUSNNI-Nanocore, National University of Singapore, Singapore 117411 (Singapore); Department of Physics, National University of Singapore, Singapore 117542 (Singapore); Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117576 (Singapore)

2014-05-07T23:59:59.000Z

398

Absorption spectroscopy of individual single-walled carbon nanotubes  

E-Print Network (OSTI)

Absorption spectroscopy of individual single-walled carbon nanotubes Stéphane Berciaud,a Laurent-walled carbon nanotubes (SWNTs) lead to heterogeneous samples containing mixtures of metallic and semiconducting species with a variety of lengths and defects. Optical detection at the single nanotube level should thus

Boyer, Edmond

399

Laser photothermal spectroscopy of light-induced absorption  

SciTech Connect

Basic methods of laser photothermal spectroscopy, which are used to study photoinduced absorption in various media, are briefly considered. Comparative analysis of these methods is performed and the latest results obtained in this field are discussed. Different schemes and examples of their practical implementation are considered. (review)

Skvortsov, L A [Institute of Cryptography, Communications and Informatics, Moscow (Russian Federation)

2013-01-31T23:59:59.000Z

400

Microsoft PowerPoint - SpectroscopyTechniques_EXAFS  

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

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

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


401

INFRARED ABSORPTION SPECTROSCOPY AND CHEMICAL KINETICS OF FREE RADICALS  

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

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

402

E-Print Network 3.0 - absorption spectroscopies progress Sample...  

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

nanoantenna arrays Summary: absorption (SEIRA) spectroscopy (7-14). Until recently, the bulk of SEIRA studies have revolved around... collectively en- hanced IR absorption...

403

First Results on Shear-selected Clusters from the Deep Lens Survey: Optical Imaging, Spectroscopy, and X-Ray Follow-up  

Science Journals Connector (OSTI)

We present the first sample of galaxy clusters selected on the basis of their weak gravitational lensing shear. The shear induced by a cluster is a function of its mass profile and its redshift relative to the background galaxies being sheared; in contrast to more traditional methods of selecting clusters, shear selection does not depend on the cluster's star formation history, baryon content, or dynamical state. Because mass is the property of clusters that provides constraints on cosmological parameters, the dependence on these other parameters could induce potentially important biases in traditionally selected samples. Comparison of a shear-selected sample with optically and X-ray-selected samples is therefore of great importance. Here we present the first step toward a new shear-selected sample: the selection of cluster candidates from the first 8.6 deg2 of the 20 deg2 Deep Lens Survey (DLS), and tabulation of their basic properties such as redshifts and optical and X-ray counterparts.

D. Wittman; I. P. Dell'Antonio; J. P. Hughes; V. E. Margoniner; J. A. Tyson; J. G. Cohen; D. Norman

2006-01-01T23:59:59.000Z

404

E-Print Network 3.0 - absorption spectroscopy Sample Search Results  

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

.619 nm Calculate the energy of the photon: h 1.633 aJ Absorption Spectroscopy In absorption... Atomic Spectroscopy Planck's constant: h 6.62608 10 34- joule sec: Speed of...

405

E-Print Network 3.0 - absorption spectroscopy q-xas Sample Search...  

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

.619 nm Calculate the energy of the photon: h 1.633 aJ Absorption Spectroscopy In absorption... Atomic Spectroscopy Planck's constant: h 6.62608 10 34- joule sec: Speed of...

406

X-ray radiation effects in multilayer epitaxial graphene Jeremy Hicks1  

E-Print Network (OSTI)

1 X-ray radiation effects in multilayer epitaxial graphene Jeremy Hicks1 , Rajan Arora2 , Eleazar and after exposure to a total ionizing dose (TID) of 12 Mrad(SiO2) using a 10 keV X-ray source. While we are mostly unaffected by radiation exposure. Combined with X-ray photoelectron spectroscopy (XPS) data

407

X-ray Fluorescence Measurements of Manganese in Petroglyphs and Graffiti in the Bluff, Utah Area  

E-Print Network (OSTI)

X-ray Fluorescence Measurements of Manganese in Petroglyphs and Graffiti in the Bluff, Utah Area the age of rock art using Mn levels, Lytle (2008). In this work we use x-ray fluorescence (XRF) to measure of methods including atomic mass spectroscopy (AMS) measurements of 14 C, Particle-induced X-ray Excitation

408

X-ray fluorescence mapping  

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

biololgical cells, over the measurement of impurities in solar cells, to the rare earth content of geological materials. A somewhat 'typical' layout for a X-ray fluorescence...

409

Infrared absorption spectroscopy and chemical kinetics of free radicals  

SciTech Connect

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.

Curl, R.F.; Glass, G.P. [Rice Univ., Houston, TX (United States)

1993-12-01T23:59:59.000Z

410

Hydrothermal Synthesis and Characterization of a Metal–Organic Framework by Thermogravimetric Analysis, Powder X-ray Diffraction, and Infrared Spectroscopy: An Integrative Inorganic Chemistry Experiment  

Science Journals Connector (OSTI)

Upper-Division Undergraduate; Inorganic Chemistry; Laboratory Instruction; Gravimetric Analysis; Hydrogen Bonding; IR Spectroscopy; Materials Science; Thermal Analysis ...

Johanna L. Crane; Kelly E. Anderson; Samantha G. Conway

2014-10-10T23:59:59.000Z

411

Determination of Tellurium by Atomic-absorption Spectroscopy with Electrothermal Atomisation  

E-Print Network (OSTI)

305 Determination of Tellurium by Atomic-absorption Spectroscopy with Electrothermal Atomisation at sub-microgram levels by atomic-absorption spectroscopy ,,'ith electrothermal atomisation after the e generation -atomic-absorption spectroscopy. The prior con- version of tellurium into hydrogen telluride

Canberra, University of

412

Analysis of the near-edge X-ray-absorption fine-structure of anthracene: A combined theoretical and experimental study  

SciTech Connect

The near-edge fine structure of the carbon K-edge absorption spectrum of anthracene was measured and theoretically analyzed by density functional theory calculations implemented in the StoBe code. It is demonstrated that the consideration of electronic relaxation of excited states around localized core holes yields a significant improvement of the calculated excitation energies and reproduces the experimentally observed fine structure well. The detailed analysis of excitation spectra calculated for each symmetry inequivalent excitation center allows in particular to examine the influence of chemical shifts and core hole effects on the excitation energies. Moreover, the visualization of final states explains the large variations in the oscillator strength of various transitions as well as the nature of Rydberg-states that exhibit a notable density of states below the ionization potentials.

Klues, Michael; Witte, Gregor, E-mail: gregor.witte@physik.uni-marburg.de [Molekulare Festkörperphysik, Philipps-Universität Marburg (Germany)] [Molekulare Festkörperphysik, Philipps-Universität Marburg (Germany); Hermann, Klaus, E-mail: hermann@FHI-Berlin.MPG.de [Inorganic Chemistry Department, Fritz-Haber-Institut der Max-Planck-Gesellschaft, Berlin (Germany)] [Inorganic Chemistry Department, Fritz-Haber-Institut der Max-Planck-Gesellschaft, Berlin (Germany)

2014-01-07T23:59:59.000Z

413

Opacity of iron, nickel, and copper plasmas in the x-ray wavelength range: Theoretical interpretation of 2p-3d absorption spectra  

SciTech Connect

This paper deals with theoretical studies on the 2p-3d absorption in iron, nickel, and copper plasmas related to LULI2000 (Laboratoire pour l'Utilisation des Lasers Intenses, 2000J facility) measurements in which target temperatures were of the order of 20 eV and plasma densities were in the range 0.004-0.01 g/cm{sup 3}. The radiatively heated targets were close to local thermodynamic equilibrium (LTE). The structure of 2p-3d transitions has been studied with the help of the statistical superconfiguration opacity code sco and with the fine-structure atomic physics codes hullac and fac. A new mixed version of the sco code allowing one to treat part of the configurations by detailed calculation based on the Cowan's code rcg has been also used in these comparisons. Special attention was paid to comparisons between theory and experiment concerning the term features which cannot be reproduced by sco. The differences in the spin-orbit splitting and the statistical (thermal) broadening of the 2p-3d transitions have been investigated as a function of the atomic number Z. It appears that at the conditions of the experiment the role of the term and configuration broadening was different in the three analyzed elements, this broadening being sensitive to the atomic number. Some effects of the temperature gradients and possible non-LTE effects have been studied with the help of the radiative-collisional code scric. The sensitivity of the 2p-3d structures with respect to temperature and density in medium-Z plasmas may be helpful for diagnostics of LTE plasmas especially in future experiments on the {Delta}n=0 absorption in medium-Z plasmas for astrophysical applications.

Blenski, T.; Loisel, G.; Poirier, M.; Thais, F.; Arnault, P.; Caillaud, T.; Fariaut, J.; Gilleron, F.; Pain, J.-C.; Porcherot, Q.; Reverdin, C.; Silvert, V.; Villette, B.; Bastiani-Ceccotti, S.; Turck-Chieze, S.; Foelsner, W.; Gaufridy de Dortan, F. de [CEA, IRAMIS, Service 'Photons, Atomes et Molecules', Centre d'Etudes de Saclay, F-91191 Gif-sur-Yvette Cedex (France); CEA, DAM, DIF, F-91297 Arpajon (France); LULI, UMR No. 7605 CNRS - Ecole Polytechnique, F-91128 Palaiseau Cedex (France); CEA, IRFU, Service d'Astrophysique, Centre d'Etudes de Saclay, F-91191 Gif-sur-Yvette Cedex (France); Max-Planck-Institut fuer Quantenoptik, D-85748 Garching (Germany); Institute of Nuclear Fusion, Universidad Politecnica de Madrid, Spain and Laboratoire d'Optique Appliquee, ENSTA-Paritech-Polytechnique, Chemin de la Huniere, F-91671 Palaiseau (France)

2011-09-15T23:59:59.000Z

414

Fresnel and refractive lenses for X-rays  

Science Journals Connector (OSTI)

We present a Gaussian beam analysis of X-ray refractive and Fresnel lenses. The X-ray refractive lens is featured by an intrinsic soft (Gaussian) aperture due to strong absorption of X-rays by materials. We defined a parameter N0, the critical Fresnel number (CFN), to describe this optical property. The values of N0 for all practical materials are below 1000 for photon energies exceeding 30 eV, still lower for high-Z materials. The maximum effective Fresnel number of a lens is determined by its material to be 2N0 and its maximum enhancement of X-ray intensity is limited to (2?N0)2, independent of its shape. We found that the refractive lens is likely to be useful for manipulating nearly diffraction limited beam in the hard X-ray region and its application is severely restricted by available fabrication capabilities today. X-ray Fresnel lenses, both in cylindrical and linear forms, are proposed as superior focusing elements for hard X-rays. Their high efficiency, up to 100% in optimal construction, will enable us to manipulate beams with multiple lenses and obtain higher performance optics. Their design and fabrication are discussed in reference to those of X-ray Fresnel zone plates and micro Fresnel lenses for optoelectronics.

B.X. Yang

1993-01-01T23:59:59.000Z

415

X-Ray Interactions with Matter from the Center for X-Ray Optics (CXRO)  

DOE Data Explorer (OSTI)

The primary interactions of low-energy x-rays within condensed matter, viz. photoabsorption and coherent scattering, are described for photon energies outside the absorption threshold regions by using atomic scattering factors. The atomic scattering factors may be accurately determined from the atomic photoabsorption cross sections using modified Kramers-Kronig dispersion relations. From a synthesis of the currently available experimental data and recent theoretical calculations for photoabsorption, the angle-independent, forward-scattering components of the atomic scattering factors have been thus semiempirically determined and tabulated here for 92 elements and for the region 50-30,000 eV. Atomic scattering factors for all angles of coherent scattering and at the higher photon energies are obtained from these tabulated forward-scattering values by adding a simple angle-dependent form-factor correction. The incoherent scattering contributions that become significant for the light elements at the higher photon energies are similarly determined. The basic x-ray interaction relations that are used in applied x-ray physics are presented here in terms of the atomic scattering factors. The bulk optical constants are also related to the atomic scattering factors. These atomic and optical relations are applied to the detailed calculation of the reflectivity characteristics of a series of practical x-ray mirror, multilayer, and crystal monochromators. Comparisons of the results of this semiempirical,"atom-like", description of x-ray interactions for the low-energy region with those of experiment and ab initio theory are presented.

Henke, B.L.; Gullikson, E.M.; Davis, J.C.

416

E-Print Network 3.0 - ambient-pressure x-ray photoelectron Sample...  

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

Spectroscopie Electronique, Summary: of an X-ray source from measurements of the kinetic energy and intensity of the photoelectrons emitted... applications in electron probe...

417

X-ray shearing interferometer  

DOE Patents (OSTI)

An x-ray interferometer for analyzing high density plasmas and optically opaque materials includes a point-like x-ray source for providing a broadband x-ray source. The x-rays are directed through a target material and then are reflected by a high-quality ellipsoidally-bent imaging crystal to a diffraction grating disposed at 1.times. magnification. A spherically-bent imaging crystal is employed when the x-rays that are incident on the crystal surface are normal to that surface. The diffraction grating produces multiple beams which interfere with one another to produce an interference pattern which contains information about the target. A detector is disposed at the position of the image of the target produced by the interfering beams.

Koch, Jeffrey A. (Livermore, CA)

2003-07-08T23:59:59.000Z

418

Dynamic model of anisotropic x-ray refraction  

Science Journals Connector (OSTI)

General mechanisms of anisotropic x-ray refraction at the resonance energy are investigated on the basis of dynamic-scattering theory. The deductions show that x rays within the crystals that have anisotropic susceptibility are completely polarized and have two elliptical polarization states. Analytical expressions of the elliptical axes, refractive indices, and absorption coefficients for these two types of polarized waves are obtained in terms of the anisotropic components of the susceptibility tensor. Anisotropic birefringence and dichroism effects associated with the polarization properties of the x-ray waves are also illustrated theoretically.

X. R. Huang, Yong Li, W. J. Liu, and S. S. Jiang

1997-11-01T23:59:59.000Z

419

MICROANALYSIS OF NY/NJ HARBOR SEDIMENTS USING SYNCHROTRON X-RAY BEAMS.  

SciTech Connect

Sediments found in the New York/New Jersey Harbor are widely contaminated with organic and inorganic compounds of anthropogenic origin. As a result, the environmental health of the Harbor has deteriorated and the efficient operation of the Port compromised by difficulties in disposing of sediments resulting from maintenance and improvements of navigational channels. Knowledge of the properties of the sediments on a micro-scale is useful in understanding the transport of contaminants through the environment, for developing effective methods for sediment decontamination, and for subsequent beneficial use of the cleaned sediments. We have investigated several properties of these sediments using synchrotron radiation techniques. These include computed microtomography using absorption and fluorescence contrast mechanisms, x-ray microscopy, microbeam x-ray fluorescence, and Fourier Transform Infrared Spectroscopy (FTIR) for measurements of microstructure, distribution of metals on individual sediment particles, and chemical forms of the contaminants on a micrometer scale. Typical results obtained with these techniques are presented.

JONES,K.W.FENG,H.LANZIROTTI,A.MARINKOVIC,N.ET AL.

2003-12-31T23:59:59.000Z

420

Observation of strontium segregation in LaAlO{sub 3}/SrTiO{sub 3} and NdGaO{sub 3}/SrTiO{sub 3} oxide heterostructures by X-ray photoemission spectroscopy  

SciTech Connect

LaAlO{sub 3} and NdGaO{sub 3} thin films of different thicknesses have been grown by pulsed laser deposition on TiO{sub 2}-terminated SrTiO{sub 3} single crystals and investigated by soft X-ray photoemission spectroscopy. The surface sensitivity of the measurements has been tuned by varying photon energy h? and emission angle ?. In contrast to the core levels of the other elements, the Sr 3d line shows an unexpected splitting for higher surface sensitivity, signaling the presence of a second strontium component. From our quantitative analysis we conclude that during the growth process Sr atoms diffuse away from the substrate and segregate at the surface of the heterostructure, possibly forming strontium oxide.

Treske, Uwe; Heming, Nadine; Knupfer, Martin; Büchner, Bernd; Koitzsch, Andreas, E-mail: a.koitzsch@ifw-dresden.de [Institute for Solid State Research, IFW-Dresden, P.O. Box 270116, DE-01171 Dresden (Germany); Di Gennaro, Emiliano; Scotti di Uccio, Umberto; Miletto Granozio, Fabio [CNR-SPIN and Dipartimento di Fisica, Complesso Universitario di Monte S. Angelo, Via Cintia, 80126 Naples (Italy); Krause, Stefan [Helmholtz-Zentrum Berlin, BESSY, Albert-Einstein-Str. 15, 12489 Berlin (Germany)

2014-01-01T23:59:59.000Z

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


421

Optics for X-Ray Laser and Laser Plasma Soft X-Ray Radiation  

Science Journals Connector (OSTI)

Focusing X-ray grazing incidence optics for X-ray laser and laser plasma soft X-ray radiation has been studied. ... computer code. Parabolic axisymmetric mirror for focusing Princeton X-ray laser beam and ellipso...

L. Pina; A. Inneman; R. Hudec

1996-01-01T23:59:59.000Z

422

Practical Performance of Energy-Dispersive X-Ray Spectroscopy with a High-Voltage TEM up to 1,000 kV  

Science Journals Connector (OSTI)

......microprobe and electron energy-loss spectroscopy on...microscope equipped with EDS and energy filtered imaging system...Hashimoto H. Kanao Y: Energy dependence of contamination...beam testing technology. New York and London: Plenum Press......

Kazuo Furuya; Mitsuaki Osaki; Mitsuhiro Awaji; Tetsuya Saito

1996-08-01T23:59:59.000Z

423

Sure, a textbook can tell you about Bragg's Law and the x-ray absorption energies for any element in the periodic table, but it can't tell you how to plan and carry out an x-ray scattering experiment at one of the 50 or so synchrotron radiation facilitie  

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

Report Report SSRL 6 th Annual School on Synchrotron X-ray Scattering Techniques in Materials and Environmental Sciences: Theory and Application SSRL SR-XRS participants. Synchrotron-based X-ray scattering (SR-XRS) techniques offer the ability to probe nano- and atomic-scale structure that dictates the properties of advanced technological and environmental materials. Important materials studied at the Stanford Synchrotron Radiation Lightsource (SSRL) include organic and inorganic thin films and interfaces, nanoparticles, complex oxides, solutions, polymers, minerals and poorly crystalline materials. Good planning and a good working knowledge of beam lines and techniques are required to successfully conduct SR-XRS measurements. This sixth annual School at SSRL on Synchrotron X-ray

424

Lensless X-Ray Imaging in Reflection  

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

Lensless X-Ray Imaging in Reflection Lensless X-Ray Imaging in Reflection Print Wednesday, 26 October 2011 00:00 The advent of x-ray free-electron laser (XFEL) light sources has...

425

Miniature x-ray source  

DOE Patents (OSTI)

A miniature x-ray source utilizing a hot filament cathode. The source has a millimeter scale size and is capable of producing broad spectrum x-ray emission over a wide range of x-ray energies. The miniature source consists of a compact vacuum tube assembly containing the hot filament cathode, an anode, a high voltage feedthru for delivering high voltage to the cathode, a getter for maintaining high vacuum, a connector for initial vacuum pump down and crimp-off, and a high voltage connection for attaching a compact high voltage cable to the high voltage feedthru. At least a portion of the vacuum tube wall is fabricated from highly x-ray transparent materials, such as sapphire, diamond, or boron nitride.

Trebes, James E. (Livermore, CA); Bell, Perry M. (Tracy, CA); Robinson, Ronald B. (Modesto, CA)

2000-01-01T23:59:59.000Z

426

X-ray Stacking 2008-Apr-22 Astrostats X-ray Stacking  

E-Print Network (OSTI)

X-ray Stacking 2008-Apr-22 Astrostats X-ray Stacking Tom Aldcroft SAO/CXC #12;X-ray Stacking 2008 analysis for a sample Stacking ­ mean properties of sample Chandra X-ray data (faint point sources) are photon-limited with low background => stacking in X-rays is very effective #12;X-ray Stacking 2008-Apr-22

Wolfe, Patrick J.

427

Optical Absorption and Photoluminescence Excitation Spectroscopy of SWNTs S. Maruyama1  

E-Print Network (OSTI)

Optical Absorption and Photoluminescence Excitation Spectroscopy of SWNTs S. Maruyama1 , Y-mail: maruyama@photon.t.u-tokyo.ac.jp Optical absorption and photoluminescence excitation (PLE) spectroscopy to the physical interest in unique excitonic features of 1-D material [3-5], clear identification of absorption

Maruyama, Shigeo

428

Absorption and photoluminescence spectroscopy on a single self-assembled charge-tunable quantum dot  

E-Print Network (OSTI)

Absorption and photoluminescence spectroscopy on a single self-assembled charge-tunable quantum dot PL and absorption spectroscopy on the same single self- assembled quantum dot in a charge the corresponding transition in absorption. We have developed a model of the Coulomb blockade to account

Ludwig-Maximilians-Universität, München

429

Tokamak x ray diagnostic instrumentation  

SciTech Connect

Three classes of x-ray diagnostic instruments enable measurement of a variety of tokamak physics parameters from different features of the x-ray emission spectrum. (1) The soft x-ray (1 to 50 keV) pulse-height-analysis (PHA) diagnostic measures impurity concentrations from characteristic line intensities and the continuum enhancement, and measures the electron temperature from the continuum slope. (2) The Bragg x-ray crystal spectrometer (XCS) measures the ion temperature and neutral-beam-induced toroidal rotation velocity from the Doppler broadening and wavelength shift, respectively, of spectral lines of medium-Z impurity ions. Impurity charge state distributions, precise wavelengths, and inner-shell excitation and recombination rates can also be studied. X rays are diffracted and focused by a bent crystal onto a position-sensitive detector. The spectral resolving power E/..delta..E is greater than 10/sup 4/ and time resolution is 10 ms. (3) The x-ray imaging system (XIS) measures the spatial structure of rapid fluctuations (0.1 to 100 kHZ) providing information on MHD phenomena, impurity transport rates, toroidal rotation velocity, plasma position, and the electron temperature profile. It uses an array of silicon surface-barrier diodes which view different chords of the plasma through a common slot aperture and operate in current (as opposed to counting) mode. The effectiveness of shields to protect detectors from fusion-neutron radiation effects has been studied both theoretically and experimentally.

Hill, K.W.; Beiersdorfer, P.; Bitter, M.; Fredrickson, E.; Von Goeler, S.; Hsuan, H.; Johnson, L.C.; Liew, S.L.; McGuire, K.; Pare, V.

1987-01-01T23:59:59.000Z

430

Spectroscopic imaging, diffraction, and holography with x-ray photoemission  

SciTech Connect

X-ray probes are capable of determining the spatial structure of an atom in a specific chemical state, over length scales from about a micron all the way down to atomic resolution. Examples of these probes include photoemission microscopy, energy-dependent photoemission diffraction, photoelectron holography, and X-ray absorption microspectroscopy. Although the method of image formation, chemical-state sensitivity, and length scales can be very different, these X-ray techniques share a common goal of combining a capability for structure determination with chemical-state specificity. This workshop will address recent advances in holographic, diffraction, and direct imaging techniques using X-ray photoemission on both theoretical and experimental fronts. A particular emphasis will be on novel structure determinations with atomic resolution using photoelectrons.

Not Available

1992-02-01T23:59:59.000Z

431

X-ray Raman scattering study of aligned polyfluorene  

E-Print Network (OSTI)

We present a non-resonant inelastic x-ray scattering study at the carbon K-edge on aligned poly[9,9-bis(2-ethylhexyl)-fluorene-2,7-diyl] and show that the x-ray Raman scattering technique can be used as a practical alternative to x-ray absorption measurements. We demonstrate that this novel method can be applied to studies on aligned $\\pi$-conjugated polymers complementing diffraction and optical studies. Combining the experimental data and a very recently proposed theoretical scheme we demonstrate a unique property of x-ray Raman scattering by performing the symmetry decomposition on the density of unoccupied electronic states into $s$- and $p$-type symmetry contributions.

S. Galambosi; M. Knaapila; J. A. Soininen; K. Nyg\\aard; S. Huotari; F. Galbrecht; U. Scherf; A. P. Monkman; K. Hämäläinen

2006-08-29T23:59:59.000Z

432

National Ignition Facility core x-ray streak camera  

SciTech Connect

The National Ignition Facility (NIF) core x-ray streak camera will be used for laser performance verification experiments as well as a wide range of physics experiments in the areas of high-energy-density science, inertial confinement fusion, and basic science. The x-ray streak camera system is being designed to record time-dependent x-ray emission from NIF targets using an interchangeable family of snouts for measurements such as one-dimensional (1D) spatial imaging or spectroscopy. the NIF core x-ray streak camera will consist of an x-ray-sensitive photocathode that detects x rays with 1D spatial resolution coupled to an electron streak tube to detect a continuous time history of the x rays incident on the photocathode over selected time periods. A charge-coupled-device (CCD) readout will record the signal from the streak tube. The streak tube, CCD, and associated electronics will reside in an electromagnetic interference, and electromagnetic pulse protected, hermetically sealed, temperature-controlled box whose internal pressure is approximately 1 atm. The streak tube itself will penetrate through the wall of the box into the target chamber vacuum. We are working with a goal of a spatial resolution of 15 lp/mm with 50% contrast transfer function at the photocathode and adjustment sweep intervals of 1--50 ns. The camera spectral sensitivity extends from soft x rays to 20 keV x rays, with varying quantum efficiency based on photocathode selection. The system will have remote control, monitoring, and Ethernet communications through an embedded controller. The core streak camera will be compatible with the instrument manipulators at the OMEGA (University of Rochester) and NIF facilities.

Kimbrough, J. R.; Bell, P. M.; Christianson, G. B.; Lee, F. D.; Kalantar, D. H.; Perry, T. S.; Sewall, N. R.; Wootton, A. J.

2001-01-01T23:59:59.000Z

433

Synchrotron-Radiation Induced X-Ray Emission (SRIXE)  

SciTech Connect

Elemental analysis using emission of characteristic x rays is a well-established scientific method. The success of this analytical method is highly dependent on the properties of the source used to produce the x rays. X-ray tubes have long existed as a principal excitation source, but electron and proton beams have also been employed extensively. The development of the synchrotron radiation x-ray source that has taken place during the past 40 years has had a major impact on the general field of x-ray analysis. Even tier 40 years, science of x-ray analysis with synchrotron x-ray beams is by no means mature. Improvements being made to existing synchrotron facilities and the design and construction of new facilities promise to accelerate the development of the general scientific use of synchrotron x-ray sources for at least the next ten years. The effective use of the synchrotron source technology depends heavily on the use of high-performance computers for analysis and theoretical interpretation of the experimental data. Fortunately, computer technology has advanced at least as rapidly as the x-ray technology during the past 40 years and should continue to do so during the next decade. The combination of these technologies should bring about dramatic advances in many fields where synchrotron x-ray science is applied. It is interesting also to compare the growth and rate of acceptance of this particular research endeavor to the rates for other technological endeavors. Griibler [1997] cataloged the time required for introduction, diffusion,and acceptance of technological, economic, and social change and found mean values of 40 to 50 years. The introduction of the synchrotron source depends on both technical and non-technical factors, and the time scale at which this seems to be occurring is quite compatible with what is seen for other major innovations such as the railroad or the telegraph. It will be interesting to see how long the present rate of technological change and increase in scientific use can be maintained for the synchrotron x-ray source. A short summary of the present state of the synchrotron radiation-induced x-ray emission (SRIXE) method is presented here. Basically, SRIXE experiments can include any that depend on the detection. of characteristic x-rays produced by the incident x-ray beam born the synchrotron source as they interact with a sample. Thus, experiments done to measure elemental composition, chemical state, crystal, structure, and other sample parameters can be considered in a discussion of SRIXE. It is also clear that the experimentalist may well wish to use a variety of complementary techniques for study of a given sample. For this reason, discussion of computed microtomography (CMT) and x-ray diffraction is included here. It is hoped that this present discussion will serve as a succinct introduction to the basic ideas of SRIXE for those not working in the field and possibly help to stimulate new types of work by those starting in the field as well as by experienced practitioners of the art. The topics covered include short descriptions of (1) the properties of synchrotron radiation, (2) a description of facilities used for its production, (3) collimated microprobe, (4) focused microprobes, (5) continuum and monoenergetic excitation, (6) detection limits, (7) quantitation, (8) applications of SRIXE, (9) computed microtomography (CMT), and (10)chemical speciation using x-ray absorption near-edge structure (XANES) and extended x-ray absorption fine structure (EXAFS). An effort has been made to cite a wide variety of work from different laboratories to show the vital nature of the field.

Jones, Keith W.

1999-09-01T23:59:59.000Z

434

E-Print Network 3.0 - absorption gamma-ray spectroscopy Sample...  

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

by Explorit Topic List Advanced Search Sample search results for: absorption gamma-ray spectroscopy Page: << < 1 2 3 4 5 > >> 1 1090 IEEE TRANSACTIONS ON NUCLEAR SCIENCE,...

435

The Use of UV–Vis Absorption Spectroscopy for Studies of Natively Disordered Proteins  

Science Journals Connector (OSTI)

Absorption spectroscopy can be used to monitor structural changes upon transitions from ordered to disordered state in proteins. Changes in environment of tryptophan, tyrosine,...

Eugene A. Permyakov

2012-01-01T23:59:59.000Z

436

E-Print Network 3.0 - absorption spectroscopy principles Sample...  

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

gas analysis Alexander Fateev, Snnik Clausen Summary: applications and in particular in atomicmolecular absorption spectroscopy, the transition moment is replaced... +CO+CO2)....

437

E-Print Network 3.0 - absorption spectroscopy establishes Sample...  

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

gas analysis Alexander Fateev, Snnik Clausen Summary: applications and in particular in atomicmolecular absorption spectroscopy, the transition moment is replaced... +CO+CO2)....

438

X-Ray Tomographic Imaging of Crystal Structure at the Atomic Level P. Korecki,1,* M. Tolkiehn,2  

E-Print Network (OSTI)

X-Ray Tomographic Imaging of Crystal Structure at the Atomic Level P. Korecki,1,* M. Tolkiehn,2 D of the crystal structure from real-space projections obtained by illuminating the sample with white x rays. This approach was applied to the pattern of the directional fine structure in absorption of white x rays

Korecki, Pawe³

439

X-ray Emission from Massive Stars  

E-Print Network (OSTI)

X-ray Emission from Massive Stars David Cohen Department of Physics and Astronomy Swarthmore be related to the production of X-rays on massive stars. If so, massive stars' X-rays are much different than those found our own Sun and other cooler stars like the Sun that produce X-rays via magnetic activity

Cohen, David

440

High-Energy Diffraction-Enhanced X-ray Imaging  

SciTech Connect

In order to apply the diffraction-enhanced X-ray imaging (DEI) method for much wider variety of samples, we have developed the high-energy DEI system. The energy of X-ray was increased up to 70 keV to achieve high permeability for heavy elements. The diffraction of Si(440) was used to keep large field of view. Demonstrative observation of an electrical cable was performed using the X-ray emitted from the vertical wiggler. The obtained images visualized not only the core and ground wire made of copper but also the isolator and outer jacket made of polymer clearly. The comparison of images obtained by the DEI and the absorption-contrast imaging showed that the sensitivity of DEI is about 10 times higher than that of the absorption method for light elements, and 3 times for heavy elements.

Yoneyama, Akio; Ueda, Kazuhiro [Advanced Research Laboratory, Hitachi Ltd., 2520, Akanuma, Hatoyama, Saitama, 350-0395 (Japan); Takeda, Tohoru [Allied Health Sciences, Kitasato University, Sagamihara, Kanagawa 228-8555 (Japan); Yamazaki, Takanori [Research and Development Laboratory, Hitachi Cable, Ltd., 5-1-1, Hidakacho, Hitachi, Ibaraki, 319-1414 (Japan); Hyodo, Kazuyuki [Institute of Materials Science, High Energy Accelerator Research Organization, 1-1 Oho, Tsukuba, Ibaraki, 305-0801 (Japan)

2010-06-23T23:59:59.000Z

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


441

Compact x-ray source and panel  

DOE Patents (OSTI)

A compact, self-contained x-ray source, and a compact x-ray source panel having a plurality of such x-ray sources arranged in a preferably broad-area pixelized array. Each x-ray source includes an electron source for producing an electron beam, an x-ray conversion target, and a multilayer insulator separating the electron source and the x-ray conversion target from each other. The multi-layer insulator preferably has a cylindrical configuration with a plurality of alternating insulator and conductor layers surrounding an acceleration channel leading from the electron source to the x-ray conversion target. A power source is connected to each x-ray source of the array to produce an accelerating gradient between the electron source and x-ray conversion target in any one or more of the x-ray sources independent of other x-ray sources in the array, so as to accelerate an electron beam towards the x-ray conversion target. The multilayer insulator enables relatively short separation distances between the electron source and the x-ray conversion target so that a thin panel is possible for compactness. This is due to the ability of the plurality of alternating insulator and conductor layers of the multilayer insulators to resist surface flashover when sufficiently high acceleration energies necessary for x-ray generation are supplied by the power source to the x-ray sources.

Sampayon, Stephen E. (Manteca, CA)

2008-02-12T23:59:59.000Z

442

Assessment of the optimum degree of Sr{sub 3}Fe{sub 2}MoO{sub 9} electron-doping through oxygen removal: An X-ray powder diffraction and {sup 57}Fe Moessbauer spectroscopy study  

SciTech Connect

We describe the preparation and structural characterization by X-ray powder diffraction (XRPD) and Moessbauer spectroscopy of three electron-doped perovskites Sr{sub 3}Fe{sub 2}MoO{sub 9-{delta}} with Fe/Mo = 2 obtained from Sr{sub 3}Fe{sub 2}MoO{sub 9}. The compounds were synthesized by topotactic reduction with H{sub 2}/N{sub 2} (5/95) at 600, 700 and 800 {sup o}C. Above 800 {sup o}C the Fe/Mo ratio changes from Fe/Mo = 2-1 < Fe/Mo < 2. The structural refinements of the XRPD data for the reduced perovskites were carried out by the Rietveld profile analysis method. The crystal structure of these phases is cubic, space group Fm3-bar m, with cationic disorder at the two different B sites that can be populated in variable proportions by the Fe atoms. The Moessbauer spectra allowed determining the evolution of the different species formed after the treatments at different temperatures and confirm that Fe ions in the samples reduced at 600, 700 and 800 {sup o}C are only in the high-spin Fe{sup 3+} electronic state.

Lopez, Carlos A.; Viola, Maria del C. [Area de Quimica General e Inorganica, Departamento de Quimica, Facultad de Quimica, Bioquimica y Farmacia, Universidad Nacional de San Luis, Chacabuco y Pedernera, 5700 San Luis (Argentina)] [Area de Quimica General e Inorganica, Departamento de Quimica, Facultad de Quimica, Bioquimica y Farmacia, Universidad Nacional de San Luis, Chacabuco y Pedernera, 5700 San Luis (Argentina); Pedregosa, Jose C., E-mail: jpedreg@unsl.edu.ar [Area de Quimica General e Inorganica, Departamento de Quimica, Facultad de Quimica, Bioquimica y Farmacia, Universidad Nacional de San Luis, Chacabuco y Pedernera, 5700 San Luis (Argentina); Mercader, Roberto C., E-mail: mercader@fisica.unlp.edu.ar [Departamento de Fisica, IFLP-CONICET, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, C.C. 67, 1900 La Plata (Argentina)

2010-10-15T23:59:59.000Z

443

Band alignment of HfO{sub 2}/Al{sub 0.25}Ga{sub 0.75}N determined by x-ray photoelectron spectroscopy: Effect of SiH{sub 4} surface treatment  

SciTech Connect

The band-alignment of atomic layer deposited (ALD)-HfO{sub 2}/Al{sub 0.25}Ga{sub 0.75}N was studied by high resolution x-ray photoelectron spectroscopy measurements for both the non-passivated and SiH{sub 4} passivated AlGaN surfaces. The valence band offset and the conduction band offset for the ALD-HfO{sub 2}/Al{sub 0.25}Ga{sub 0.75}N interface were found to be 0.43?eV and 1.47?eV, respectively, for the non-passivated sample, and 0.59?eV and 1.31?eV, respectively, for the SiH{sub 4}-passivated sample. The difference in the band alignment is dominated by the band bending or band shift in the AlGaN substrate as a result of the different interlayers formed by the two surface preparations.

Samuel Owen, Man Hon, E-mail: m.owen.sg@ieee.org, E-mail: yeo@ieee.org; Amin Bhuiyan, Maruf; Zhou, Qian; Yeo, Yee-Chia, E-mail: m.owen.sg@ieee.org, E-mail: yeo@ieee.org [Department of Electrical and Computer Engineering, National University of Singapore, Singapore 119260 (Singapore); Zhang, Zheng; Sheng Pan, Ji [Institute of Materials Research and Engineering, A-STAR (Agency for Science, Technology and Research), 3 Research Link, Singapore 117602 (Singapore)

2014-03-03T23:59:59.000Z

444

In-operando hard X-ray photoelectron spectroscopy study on the impact of current compliance and switching cycles on oxygen and carbon defects in resistive switching Ti/HfO{sub 2}/TiN cells  

SciTech Connect

In this study, direct experimental materials science evidence of the important theoretical prediction for resistive random access memory (RRAM) technologies that a critical amount of oxygen vacancies is needed to establish stable resistive switching in metal-oxide-metal samples is presented. In detail, a novel in-operando hard X-ray photoelectron spectroscopy technique is applied to non-destructively investigates the influence of the current compliance and direct current voltage sweep cycles on the Ti/HfO{sub 2} interface chemistry and physics of resistive switching Ti/HfO{sub 2}/TiN cells. These studies indeed confirm that current compliance is a critical parameter to control the amount of oxygen vacancies in the conducting filaments in the oxide layer during the RRAM cell operation to achieve stable switching. Furthermore, clear carbon segregation towards the Ti/HfO{sub 2} interface under electrical stress is visible. Since carbon impurities impact the oxygen vacancy defect population under resistive switching, this dynamic carbon segregation to the Ti/HfO{sub 2} interface is suspected to negatively influence RRAM device endurance. Therefore, these results indicate that the RRAM materials engineering needs to include all impurities in the dielectric layer in order to achieve reliable device performance.

Sowinska, Malgorzata, E-mail: sowinska@ihp-microelectronics.com; Bertaud, Thomas; Walczyk, Damian; Calka, Pauline; Walczyk, Christian [IHP, Im Technologiepark 25, 15236 Frankfurt (Oder) (Germany); Thiess, Sebastian [Deutsches Elektronen-Synchrotron DESY, Notkestrasse 85, 22607 Hamburg (Germany); Alff, Lambert [Institute of Materials Science, Technische Universität Darmstadt, 64287 Darmstadt (Germany); Schroeder, Thomas [IHP, Im Technologiepark 25, 15236 Frankfurt (Oder) (Germany); Brandenburgische Technische Universität, Konrad-Zuse-Strasse 1, 03046 Cottbus (Germany)

2014-05-28T23:59:59.000Z

445

Band mapping in x-ray photoelectron spectroscopy: An experimental and theoretical study of W(110) with 1.25 keV excitation  

Science Journals Connector (OSTI)

Angle-resolved photoemission spectroscopy (ARPES) has generally been carried out at energies below ?150 eV, but there is growing interest in going to higher energies so as to achieve greater bulk sensitivity. To this end, we have measured ARPES spectra from a tungsten (110) crystal in a plane containing the [100], [110], and [010] directions with a photon energy of 1253.6 eV. The experimental data are compared to free-electron final-state calculations in an extended zone scheme with no inclusion of matrix elements, as well as highly accurate one-step theory including matrix elements. Both models provide further insight into such future higher-energy ARPES measurements. Special effects occurring in a higher-energy ARPES experiment, such as photon momentum, phonon-induced zone averaging effects, and the degree of cryogenic cooling required are discussed, together with qualitative predictions via appropriate Debye-Waller factors for future experiments with a number of representative elements being presented.

C. Papp; L. Plucinski; J. Minar; J. Braun; H. Ebert; C. M. Schneider; C. S. Fadley

2011-07-18T23:59:59.000Z

446

Unexpected Angular Dependence of X-Ray Magnetic Linear Dichroism  

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

Unexpected Angular Dependence of X-Ray Magnetic Linear Dichroism Print Unexpected Angular Dependence of X-Ray Magnetic Linear Dichroism Print Using spectroscopic information for magnetometry and magnetic microscopy obviously requires detailed theoretical understanding of spectral shape and magnitude of dichroism signals. A research team at ALS Beamline 4.0.2 has now shown unambiguously that, contrary to common belief, spectral shape and magnitude of x-ray magnetic linear dichroism (XMLD) are not only determined by the relative orientation of magnetic moments and x-ray polarization, but their orientation relative to the crystallographic axes must be taken into account for accurate interpretation of XMLD data. Magnetism and X Rays The ancient Greeks and also the Chinese knew about strange and rare stones with the power to attract iron. Moreover, when freely suspended these objects pointed north-south. Throughout the past, we have used this phenomenon-magnetism-for navigation and more recently for power production and digital information storage, all while trying to explore and understand its origins. In 1986 researchers at a facility similar to the ALS observed for the first time that the absorption of x rays depends not only on the composition of a material-that is, if it contains iron, nickel, or other elements-but also on its magnetism. The effect is unique in that it allows us to distinguish which atomic species magnetism originates from and provides information about their local atomic environment-for example, whether a magnetic species is surrounded by 4 or 6 oxygen atoms. A research team at the ALS has now shown that the relationship between magnetic order and absorption of x rays is even more complex and exciting than has been assumed for the past 20 years, leading to a reassessment of previous results.

447

Unexpected Angular Dependence of X-Ray Magnetic Linear Dichroism  

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

Unexpected Angular Dependence of X-Ray Magnetic Linear Dichroism Print Unexpected Angular Dependence of X-Ray Magnetic Linear Dichroism Print Using spectroscopic information for magnetometry and magnetic microscopy obviously requires detailed theoretical understanding of spectral shape and magnitude of dichroism signals. A research team at ALS Beamline 4.0.2 has now shown unambiguously that, contrary to common belief, spectral shape and magnitude of x-ray magnetic linear dichroism (XMLD) are not only determined by the relative orientation of magnetic moments and x-ray polarization, but their orientation relative to the crystallographic axes must be taken into account for accurate interpretation of XMLD data. Magnetism and X Rays The ancient Greeks and also the Chinese knew about strange and rare stones with the power to attract iron. Moreover, when freely suspended these objects pointed north-south. Throughout the past, we have used this phenomenon-magnetism-for navigation and more recently for power production and digital information storage, all while trying to explore and understand its origins. In 1986 researchers at a facility similar to the ALS observed for the first time that the absorption of x rays depends not only on the composition of a material-that is, if it contains iron, nickel, or other elements-but also on its magnetism. The effect is unique in that it allows us to distinguish which atomic species magnetism originates from and provides information about their local atomic environment-for example, whether a magnetic species is surrounded by 4 or 6 oxygen atoms. A research team at the ALS has now shown that the relationship between magnetic order and absorption of x rays is even more complex and exciting than has been assumed for the past 20 years, leading to a reassessment of previous results.

448

Focused X-ray source  

DOE Patents (OSTI)

Disclosed is an intense, relatively inexpensive X-ray source (as compared to a synchrotron emitter) for technological, scientific, and spectroscopic purposes. A conical radiation pattern produced by a single foil or stack of foils is focused by optics to increase the intensity of the radiation at a distance from the conical radiator. 8 figs.

Piestrup, M.A.; Boyers, D.G.; Pincus, C.I.; Maccagno, P.

1990-08-21T23:59:59.000Z

449

External Cavity Quantum Cascade Laser for Quartz Tuning Fork Photoacoustic Spectroscopy of Broad Absorption Features  

SciTech Connect

We demonstrate mid-infrared spectroscopy of large molecules with broad absorption features using a tunable external cavity quantum cascade laser. Absorption spectra for two different Freons are measured over the range 1130-1185 cm-1 with 0.2 cm-1 resolution via laser photoacoustic spectroscopy with quartz tuning forks as acoustic transducers. The measured spectra are in excellent agreement with published reference absorption spectra.

Phillips, Mark C.; Myers, Tanya L.; Wojcik, Michael D.; Cannon, Bret D.

2007-05-01T23:59:59.000Z

450

Atomic flux measurement by diode-laser-based atomic absorption spectroscopy  

E-Print Network (OSTI)

Atomic flux measurement by diode-laser-based atomic absorption spectroscopy Weizhi Wang,a) R. H, California 94305 Received 5 May 1999; accepted 6 June 1999 Diode-laser-based atomic absorption AA sensors- quirements, and only the QCM measures the flux. Lamp- based atomic absorption AA sensors have been success

Fejer, Martin M.

451

Broadband absorption spectroscopy in turbid media by combined frequency-domain and  

E-Print Network (OSTI)

Broadband absorption spectroscopy in turbid media by combined frequency-domain and steady. Tromberg A technique for measuring broadband near-infrared absorption spectra of turbid media that uses selected wavelengths. Coefficients of absorption a and reduced scattering s derived from the FD data

Berger, Andrew J.