Powered by Deep Web Technologies
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.


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

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.

4

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.

5

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

6

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

7

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

8

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

9

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

10

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

11

SMB, X-ray Absorption Spectroscopy  

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

AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr MayAtmosphericNuclear Security Administration the1 -the Mid-Infrared0 ResourceAwards SAGE Awards ,#2446Small Angle X-Ray

12

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

13

X-ray Absorption Spectroscopy: a powerful tool for the investigation  

E-Print Network [OSTI]

X-ray Absorption Spectroscopy: a powerful tool for the investigation of the role of metals is to illustrate the potentialities of X-ray Absorption Spectroscopy (XAS) to investigate structural properties Protein and Zinc ions 2 Introduction to the X-ray Absorption Spec- troscopy XAS uses Synchrotron Radiation

Morante, Silvia

14

ON THE USE OF EXTENDED X-RAY ABSORPTION FINE STRUCTURE SPECTROSCOPY TO DETERMINE THE BONDING CONFIGURATIONS OF  

E-Print Network [OSTI]

ON THE USE OF EXTENDED X-RAY ABSORPTION FINE STRUCTURE SPECTROSCOPY TO DETERMINE THE BONDING Rights Reserved #12;ON THE USE OF EXTENDED X-RAY ABSORPTION FINE STRUCTURE SPECTROSCOPY TO DETERMINE

Sparks, Donald L.

15

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

16

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

17

X-ray absorption spectroscopy of biomimetic dye molecules for solar cells Peter L. Cook,1  

E-Print Network [OSTI]

X-ray absorption spectroscopy of biomimetic dye molecules for solar cells Peter L. Cook,1 Xiaosong November 2009 Dye-sensitized solar cells are potentially inexpensive alternatives to traditional semiconductor solar cells. In order to optimize dyes for solar cells we systematically investigate

Himpsel, Franz J.

18

A new endstation at the Swiss Light Source for ultraviolet photoelectron spectroscopy, X-ray photoelectron spectroscopy, and X-ray absorption spectroscopy measurements of liquid solutions  

SciTech Connect (OSTI)

A new liquid microjet endstation designed for ultraviolet (UPS) and X-ray (XPS) photoelectron, and partial electron yield X-ray absorption (XAS) spectroscopies at the Swiss Light Source is presented. The new endstation, which is based on a Scienta HiPP-2 R4000 electron spectrometer, is the first liquid microjet endstation capable of operating in vacuum and in ambient pressures up to the equilibrium vapor pressure of liquid water at room temperature. In addition, the Scienta HiPP-2 R4000 energy analyzer of this new endstation allows for XPS measurements up to 7000 eV electron kinetic energy that will enable electronic structure measurements of bulk solutions and buried interfaces from liquid microjet samples. The endstation is designed to operate at the soft X-ray SIM beamline and at the tender X-ray Phoenix beamline. The endstation can also be operated using a Scienta 5 K ultraviolet helium lamp for dedicated UPS measurements at the vapor-liquid interface using either He I or He II ? lines. The design concept, first results from UPS, soft X-ray XPS, and partial electron yield XAS measurements, and an outlook to the potential of this endstation are presented.

Brown, Matthew A.; Redondo, Amaia Beloqui; Duyckaerts, Nicolas; Mächler, Jean-Pierre [Institute for Chemical and Bioengineering, ETH Zürich, CH-8093 Zürich (Switzerland)] [Institute for Chemical and Bioengineering, ETH Zürich, CH-8093 Zürich (Switzerland); Jordan, Inga; Wörner, Hans Jakob [Laboratory of Physical Chemistry, ETH Zürich, CH-8093 Zürich (Switzerland)] [Laboratory of Physical Chemistry, ETH Zürich, CH-8093 Zürich (Switzerland); Lee, Ming-Tao; Ammann, Markus; Nolting, Frithjof; Kleibert, Armin; Huthwelker, Thomas; Birrer, Mario; Honegger, Juri; Wetter, Reto [Paul Scherrer Institute, CH-5232 Villigen PSI (Switzerland)] [Paul Scherrer Institute, CH-5232 Villigen PSI (Switzerland); Bokhoven, Jeroen A. van [Institute for Chemical and Bioengineering, ETH Zürich, CH-8093 Zürich (Switzerland) [Institute for Chemical and Bioengineering, ETH Zürich, CH-8093 Zürich (Switzerland); Paul Scherrer Institute, CH-5232 Villigen PSI (Switzerland)

2013-07-15T23:59:59.000Z

19

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

20

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

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

Use of X-ray Absorption Spectroscopy to Distinguish Between Inner And Outer-sphere Pb Adsorption Complexes on Montmorillonite  

E-Print Network [OSTI]

Use of X-ray Absorption Spectroscopy to Distinguish Between Inner And Outer-sphere Pb Adsorption on the functional groups at the edges of the montmorillonite. At I = 0.002 M Pb absorption was less dependent

Sparks, Donald L.

22

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

SciTech Connect (OSTI)

A simple gas cell design, constructed primarily from commercially available components, enables in situ soft X-ray transmission-absorption spectroscopy of materials in contact with gas at ambient temperature. The cell has a minimum X-ray path length of 1 mm and can hold gas pressures up to ?300 Torr, and could support higher pressures with simple modifications. The design enables cycling between vacuum and gas environments without interrupting the X-ray beam, and can be fully sealed to allow for measurements of air-sensitive samples. The cell can attach to the downstream port of any appropriate synchrotron beamline, and offers a robust and versatile method for in situ measurements of certain materials. The construction and operation of the cell are discussed, as well as sample preparation and proper spectral analysis, illustrated by examples of spectral measurements. Potential areas for improvement and modification for specialized applications are also mentioned.

Drisdell, W. S.; Kortright, J. B. [Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)

2014-07-15T23:59:59.000Z

23

Electrochemical flowcell for in-situ investigations by soft x-ray absorption and emission spectroscopy  

SciTech Connect (OSTI)

A new liquid flow-cell designed for electronic structure investigations at the liquid-solid interface by soft X-ray absorption and emission spectroscopy is presented. A thin membrane serves simultaneously as a substrate for the working electrode and solid state samples as well as for separating the liquid from the surrounding vacuum conditions. In combination with counter and reference electrodes this approach allows in-situ studies of electrochemical deposition processes and catalytic reactions at the liquid-solid interface in combination with potentiostatic measurements. As model system in-situ monitoring of the deposition process of Co metal from a 10 mM CoCl{sub 2} aqueous solution by X-ray absorption and emission spectroscopy is presented.

Schwanke, C.; Lange, K. M., E-mail: Kathrin.lange@helmholtz-berlin.de [Helmholtz-Zentrum Berlin für Materialien und Energie, Institute of Solar Fuels, Albert-Einstein-Straße 15, 12489 Berlin (Germany); Golnak, R.; Xiao, J. [Helmholtz-Zentrum Berlin für Materialien und Energie, Institute of Methods for Material Development, Albert-Einstein-Straße 15, 12489 Berlin (Germany)

2014-10-15T23:59:59.000Z

24

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

SciTech Connect (OSTI)

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

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

SciTech Connect (OSTI)

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

26

GEOC Thursday, March 25, 2010 192 -In situ characterization of environmental redox reactions using quick-scanning X-ray absorption spectroscopy  

E-Print Network [OSTI]

quick-scanning X-ray absorption spectroscopy (Q-XAS) Donald L Sparks, Dr. Matthew Ginder-Vogel, Dr. In this presentation, we will describe the use of quick X-ray absorption spectroscopy (Q-XAS), at a subsecond time by calculated rate constants that do not change with concentration. In addition to using X-ray absorption near

Sparks, Donald L.

27

Use of X-Ray Absorption Spectroscopy to Monitor the Kinetics of Metal Sorption Reactions at the Soil/Water Interface  

E-Print Network [OSTI]

Use of X-Ray Absorption Spectroscopy to Monitor the Kinetics of Metal Sorption Reactions on the surface coordination environment of Ni sorbed onto clays and aluminum oxides using X-ray absorption fine

Sparks, Donald L.

28

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

SciTech Connect (OSTI)

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

Balasubramanian, M.

1998-06-02T23:59:59.000Z

29

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

SciTech Connect (OSTI)

Quantification of synchrotron XRF analyses is typically done through comparisons with measurements on the NIST SRM 1832/1833 thin film standards. Unfortunately, these standards are inhomogeneous on small scales at the tens of percent level. We are synthesizing new homogeneous multilayer standards using the Atomic Layer Deposition technique and characterizing them using multiple analytical methods, including ellipsometry, Rutherford Back Scattering at Evans Analytical, Synchrotron X-ray Fluorescence (SXRF) at Advanced Photon Source (APS) Beamline 13-ID, Synchrotron X-ray Absorption Spectroscopy (XAS) at Advanced Light Source (ALS) Beamlines 11.0.2 and 5.3.2.1 and by electron microscopy techniques. Our motivation for developing much-needed cross-calibration of synchrotron techniques is borne from coordinated analyses of particles captured in the aerogel of the NASA Stardust Interstellar Dust Collector (SIDC). The Stardust Interstellar Dust Preliminary Examination (ISPE) team have characterized three sub-nanogram, {approx}1{micro}m-sized fragments considered as candidates to be the first contemporary interstellar dust ever collected, based on their chemistries and trajectories. The candidates were analyzed in small wedges of aerogel in which they were extracted from the larger collector, using high sensitivity, high spatial resolution >3 keV synchrotron x-ray fluorescence spectroscopy (SXRF) and <2 keV synchrotron x-ray transmission microscopy (STXM) during Stardust ISPE. The ISPE synchrotron techniques have complementary capabilities. Hard X-ray SXRF is sensitive to sub-fg mass of elements Z {ge} 20 (calcium) and has a spatial resolution as low as 90nm. X-ray Diffraction data were collected simultaneously with SXRF data. Soft X-ray STXM at ALS beamline 11.0.2 can detect fg-mass of most elements, including cosmochemically important oxygen, magnesium, aluminum and silicon, which are invisible to SXRF in this application. ALS beamline 11.0.2 has spatial resolution better than 25 nm. Limiting factors for Stardust STXM analyses were self-imposed limits of photon dose due to radiation damage concerns, and significant attenuation of <1500 eV X-rays by {approx}80{micro}m thick, {approx}25 mg/cm{sup 3} density silica aerogel capture medium. In practice, the ISPE team characterized the major, light elements using STXM (O, Mg, Al, Si) and the heavier minor and trace elements using SXRF. The two data sets overlapped only with minor Fe and Ni ({approx}1% mass abundance), providing few quantitative cross-checks. New improved standards for cross calibration are essential for consortium-based analyses of Stardust interstellar and cometary particles, IDPs. Indeed, they have far reaching application across the whole synchrotron-based analytical community. We have synthesized three ALD multilayers simultaneously on silicon nitride membranes and silicon and characterized them using RBS (on Si), XRF (on Si{sub 3}N{sub 4}) and STXM/XAS (holey Si{sub 3}N{sub 4}). The systems we have started to work with are Al-Zn-Fe and Y-Mg-Er. We have found these ALD multi-layers to be uniform at {micro}m- to nm scales, and have found excellent consistency between four analytical techniques so far. The ALD films can also be used as a standard for e-beam instruments, eg., TEM EELS or EDX. After some early issues with the consistency of coatings to the back-side of the membrane windows, we are confident to be able to show multi-analytical agreement to within 10%. As the precision improves, we can use the new standards to verify or improve the tabulated cross-sections.

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

2012-03-13T23:59:59.000Z

30

X-ray absorption spectroscopy and EPR studies of oriented spinach thylakoid preparations  

SciTech Connect (OSTI)

In this study, oriented Photosystem II (PS II) particles from spinach chloroplasts are studied with electron paramagnetic resonance (EPR) and x-ray absorption spectroscopy (XAS) to determine more details of the structure of the oxygen evolving complex (OEC). The nature of halide binding to Mn is also studied with Cl K-edge and Mn EXAFS (extended x-ray absorption fine structure) of Mn-Cl model compounds, and with Mn EXAFS of oriented PS II in which Br has replaced Cl. Attention is focused on the following: photosynthesis and the oxygen evolving complex; determination of mosaic spread in oriented photosystem II particles from signal II EPR measurement; oriented EXAFS--studies of PS II in the S{sub 2} state; structural changes in PS II as a result of treatment with ammonia: EPR and XAS studies; studies of halide binding to Mn: Cl K-edge and Mn EXAFS of Mn-Cl model compounds and Mn EXAFS of oriented Br-treated photosystem II.

Andrews, J.C. [Univ. of California, Berkeley, CA (United States). Dept. of Chemistry; [Lawrence Berkeley Lab., CA (United States). Structural Biology Div.

1995-08-01T23:59:59.000Z

31

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

SciTech Connect (OSTI)

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

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

2007-05-07T23:59:59.000Z

32

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

SciTech Connect (OSTI)

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

33

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

SciTech Connect (OSTI)

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

34

Electronic Structure of Transition Metal-Cysteine Complexes From X-Ray Absorption Spectroscopy  

SciTech Connect (OSTI)

The electronic structures of Hg{sup II}, Ni{sup II}, Cr{sup III}, and Mo{sup V} complexes with cysteine were investigated by sulfur K-edge X-ray absorption near-edge structure (XANES) spectroscopy and density functional theory. The covalency in the metal-sulfur bond was determined by analyzing the intensities of the electric-dipole allowed pre-edge features appearing in the XANES spectra below the ionization threshold. Because of the well-defined structures of the selected cysteine complexes, the current work provides a reference set for further sulfur K-edge XAS studies of bioinorganic active sites with transition metal-sulfur bonds from cysteine residues as well as more complex coordination compounds with thiolate ligands.

Leung, B.O.; Jalilehvand, F.; Szilagyi, R.K.

2009-05-19T23:59:59.000Z

35

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

SciTech Connect (OSTI)

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

Dissimilar behavior of technetium and rhenium in borosilicate waste glass as determined by X-ray absorption spectroscopy  

E-Print Network [OSTI]

by X-ray fluorescence (XRF) spectroscopy with a relativeuncertainty of 4%. XRF analyses utilized an ARL 9400X-ray fluorescence spectrometer with XRF composition values

Lukens, Wayne W.; McKeown, David A.; Buechele, Andrew C.; Muller, Isabelle S.; Shuh, David K.; Pegg, Ian L.

2006-01-01T23:59:59.000Z

37

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

SciTech Connect (OSTI)

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

38

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

SciTech Connect (OSTI)

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

39

Understanding Sulfur Poisoning and Regeneration of Nickel Biomass Conditioning Catalysts using X-Ray Absorption Spectroscopy  

SciTech Connect (OSTI)

The production of biofuels can proceed via a biomass gasification to produce syngas, which can then undergo catalytic conditioning and reforming reactions prior to being sent to a fuel synthesis reactor. Catalysts used for biomass conditioning are plagued by short lifetimes which are a result of, among other things, poisoning. Syngas produced from biomass gasification may contain between 30-300 ppm H2S, depending on the feedstock and gasification conditions, and H2S is a key catalyst poison. In order to overcome catalyst poisoning, either an H2S-tolerant catalyst or an efficient regeneration protocol should be employed. In this study, sulfur K-edge X-ray absorption near edge spectroscopy (XANES) was used to monitor sulfur species on spent catalyst samples and the transformation of these species from sulfides to sulfates during steam and air regeneration on a Ni/Mg/K/Al2O3 catalyst used to condition biomass-derived syngas. Additionally, nickel K-edge EXAFS and XANES are used to examine the state of nickel species on the catalysts. Post-reaction samples showed the presence of sulfides on the H2S-poisoned nickel catalyst and although some gaseous sulfur species were observed to leave the catalyst bed during regeneration, sulfur remained on the catalyst and a transformation from sulfides to sulfates was observed. The subsequent H2 reduction led to a partial reduction of sulfates back to sulfides. A proposed reaction sequence is presented and recommended regeneration strategies are discussed.

Yung, M. M.; Cheah, S.; Kuhn, J. N.

2013-01-01T23:59:59.000Z

40

Identification of lead chemical form in mine waste materials by X-ray absorption spectroscopy  

SciTech Connect (OSTI)

X-ray absorption spectroscopy (XAS) provides a direct means for measuring lead chemical forms in complex samples. In this study, XAS was used to identify the presence of plumbojarosite (PbFe{sub 6}(SO{sub 4}){sub 4}(OH){sub 12}) by lead L{sub 3}-edge XANES spectra in mine waste from a small gold mining operation in Fiji. The presence of plumbojarosite in tailings was confirmed by XRD but XANES gave better resolution. The potential for human uptake of Pb from tailings was measured using a physiologically based extract test (PBET), an in-vitro bioaccessibility (BAc) method. The BAc of Pb was 55%. Particle size distribution of tailings indicated that 40% of PM{sub 10} particulates exist which could be a potential risk for respiratory effects via the inhalation route. Food items collected in the proximity of the mine site had lead concentrations which exceed food standard guidelines. Lead within the mining lease exceeded sediment guidelines. The results from this study are used to investigate exposure pathways via ingestion and inhalation for potential risk exposure pathways of Pb in that locality. The highest Pb concentration in soil and tailings was 25,839 mg/kg, exceeding the Australian National Environment Protection Measure (NEPM) soil health investigation levels.

Taga, Raijeli L.; Ng, Jack [University of Queensland, National Research Centre for Environmental Toxicology (EnTox), Brisbane, 4108 (Australia); Zheng Jiajia; Huynh, Trang; Noller, Barry [University of Queensland, Centre for Mined Land Rehabilitation, Brisbane, 4072 (Australia); Harris, Hugh H. [School of Chemistry and Physics, University of Adelaide, Adelaide, 5005 (Australia)

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.


41

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

42

Design and Operation of an In Situ High Pressure Reaction Cell for X-Ray Absorption Spectroscopy  

SciTech Connect (OSTI)

The design and initial operation of an in situ catalysis reaction cell for x-ray absorption spectroscopy measurements at high pressure is described. The design is based on an x-ray transparent tube fabricated from beryllium. This forms a true plug flow reactor for catalysis studies. The reactor is coupled to a portable microprocessor-controlled versatile feed system, and incorporates on-line analysis of reaction products. XAFS data recorded during the reduction of a NiRe/carbon catalyst at 4 bar are used to illustrate the performance of the reactor.

Bare, Simon R.; Mickelson, G. E.; Modica, F. S. [UOP LLC, Des Plaines, IL, 60016 (United States); Yang, N. [Argonne National Laboratory, Argonne, IL 60439 (United States); Kelly, S. D. [EXAFS Analysis, Bolingbrook, IL 6044 (United States)

2007-02-02T23:59:59.000Z

43

How Can X-ray Transient Absorption Spectroscopy Aide Solar Energy...  

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

are from optimized on structural, energetic and dynamic parameters. Intense X-ray pulses from synchrotrons and X-ray free electrons lasers coupled with ultrafast lasers...

44

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

SciTech Connect (OSTI)

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

45

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

SciTech Connect (OSTI)

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

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

2012-02-28T23:59:59.000Z

46

Quantification of rapid environmental redox processes with quick-scanning x-ray absorption  

E-Print Network [OSTI]

Quantification of rapid environmental redox processes with quick-scanning x-ray absorption. Here we apply quick-scanning x-ray absorption spectroscopy (Q-XAS), at sub-second time that can be measured using x-ray absorption spectroscopy. arsenic extended x-ray absorption fine structure

Sparks, Donald L.

47

High Resolution Spectroscopy of X-ray Quasars: Searching for the X-ray Absorption from the Warm-Hot Intergalactic Medium  

E-Print Network [OSTI]

We present a survey of six low- to moderate-redshift quasars with Chandra and XMM-Newton. The primary goal is to search for the narrow X-ray absorption lines produced by highly ionized metals in the warm-hot intergalactic ...

Fang, Taotao

48

Atomic resolution mapping of the excited-state electronic structure of Cu2O with time-resolved x-ray absorption spectroscopy  

SciTech Connect (OSTI)

We have used time-resolved soft x-ray spectroscopy to investigate the electronic structure of optically excited cuprous oxide at the O K-edge and the Cu L3-edge. The 400 nm optical excitation shifts the Cu and O absorptions to lower energy, but does not change the integrated x-ray absorption significantly for either edge. The constant integrated x-ray absorption cross-section indicates that the conduction-band and valence-band edges have very similar Cu 3d and O 2p orbital contributions. The 2.1 eV optical band gap of Cu2O significantly exceeds the one eV shift in the Cu L3- and O K-edges absorption edges induced by optical excitation, demonstrating the importance of core-hole excitonic effects and valence electron screening in the x-ray absorption process.

Hillyard, P. W.; Kuchibhatla, S. V. N. T.; Glover, T. E.; Hertlein, M. P.; Huse, Nils; Nachimuthu, P.; Saraf, L. V.; Thevuthasan, S.; Gaffney, K. J.

2010-05-02T23:59:59.000Z

49

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

E-Print Network [OSTI]

Micro x-ray ?uorescence ( -XRF) mapping was performed using15 RESULTS AND DISCUSSION -XRF imaging was used to determinelocalisation in planta. Typical -XRF maps obtained of stem,

Kachenko, A.

2009-01-01T23:59:59.000Z

50

Iron near absorption edge X-ray spectroscopy at aqueous-membrane interfaces  

SciTech Connect (OSTI)

Employing synchrotron X-ray scattering, we systematically determine the absorption near-edge spectra (XANES) of iron in its ferrous (Fe2+) and ferric (Fe3+) states both as ions in aqueous solutions and as they bind to form a single layer to anionic templates that consist of carboxyl or phosphate groups at aqueous/vapor interfaces. While the XANES of bulk iron ions show that the electronic state and coordination of iron complexes in the bulk are isotropic, the interfacial bound ions show a signature of a broken inversion-symmetry environment. The XANES of Fe2+ and Fe3+ in the bulk possess distinct profiles however, upon binding they practically exhibit similar patterns. This indicates that both bound ions settle into a stable electronic and coordination configuration with an effective fractional valence (for example, Fe[2+nu]+, 0 < nu < 1) at charged organic templates. Such two dimensional properties may render interfacial iron, abundant in living organisms, a more efficient and versatile catalytic behavior.

Wang, Wenjie; Kuzmenko, Ivan; Vaknin, David

2014-01-01T23:59:59.000Z

51

Coupling MD Simulations and X-ray Absorption Spectroscopy to Study Ions in Solution  

SciTech Connect (OSTI)

The structure of ionic solutions is a key-point in understanding physicochemical properties of electrolyte solutions. Among the reduced number of experimental techniques which can supply direct information on the ion environment, X-ray Absorption techniques (XAS) have gained importance during the last decades although they are not free of difficulties associated to the data analysis leading to provide reliable structures. Computer simulations of ions in solution is a theoretical alternative to provide information on the solvation structure. Thus, the use of computational chemistry can increase the understanding of these systems although an accurate description of ionic solvation phenomena represents nowadays a significant challenge to theoretical chemistry. We present: (a) the assignment of features in the XANES spectrum to well defined structural motif in the ion environment, (b) MD-based evaluation of EXAFS parameters used in the fitting procedure to make easier the structural resolution, and (c) the use of the agreement between experimental and simulated XANES spectra to help in the choice of a given intermolecular potential for Computer Simulations. Chemical problems examined are: (a) the identification of the second hydration shell in dilute aqueous solutions of highly-charged cations, such as Cr{sup 3+}, Rh{sup 3+}, Ir{sup 3+}, (b) the invisibility by XAS of certain structures characterized by Computer Simulations but exhibiting high dynamical behavior and (c) the solvation of Br{sup -} in acetonitrile.

Marcos, E. Sanchez; Beret, E. C.; Martinez, J. M.; Pappalardo, R. R. [University of Seville, Dept. of Physical Chemistry (Spain); Ayala, R.; Munoz-Paez, A. [University of Seville, CSIC-ICMSE. Dept. of Inorganic Chemistry (Spain)

2007-11-29T23:59:59.000Z

52

Local versus global electronic properties of chalcopyrite alloys: X-ray absorption spectroscopy and ab initio calculations  

SciTech Connect (OSTI)

Element-specific unoccupied electronic states of Cu(In, Ga)S{sub 2} were studied as a function of the In/Ga ratio by combining X-ray absorption spectroscopy with density functional theory calculations. The S absorption edge shifts with changing In/Ga ratio as expected from the variation of the band gap. In contrast, the cation edge positions are largely independent of composition despite the changing band gap. This unexpected behavior is well reproduced by our calculations and originates from the dependence of the electronic states on the local atomic environment. The changing band gap arises from a changing spatial average of these localized states with changing alloy composition.

Sarmiento-Pérez, Rafael; Botti, Silvana, E-mail: silvana.botti@univ-lyon1.fr [Institut Lumière Matière and ETSF, UMR5306 Université Lyon 1-CNRS, Université de Lyon, F-69622 Villeurbanne Cedex (France); Schnohr, Claudia S., E-mail: c.schnohr@uni-jena.de [Institut für Festkörperphysik, Friedrich-Schiller-Universität Jena, Max-Wien-Platz 1, 07743 Jena (Germany); Lauermann, Iver [Helmholtz-Zentrum Berlin für Materialien und Energie, Hahn-Meitner Platz 1, 14109 Berlin (Germany); Rubio, Angel [Nano-Bio Spectroscopy Group and ETSF Scientific Development Centre, Departamento de Física de Materiales, Centro de Física de Materiales CSIC-MPC and DIPC, Universidad del País Vasco UPV/EHU, Avenida de Tolosa 72, E-20018 San Sebastián (Spain); Fritz Haber Institute, Max Planck Society, Faradayweg 4-6, 14195 Berlin (Germany); Johnson, Benjamin, E-mail: benjamin.johnson@alumni.tu-berlin.de [Fritz Haber Institute, Max Planck Society, Faradayweg 4-6, 14195 Berlin (Germany)

2014-09-07T23:59:59.000Z

53

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

SciTech Connect (OSTI)

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

Nagasaka, Masanari, E-mail: nagasaka@ims.ac.jp; Kosugi, Nobuhiro [Institute for Molecular Science, Myodaiji, Okazaki 444-8585 (Japan); The Graduate University for Advanced Studies, Myodaiji, Okazaki 444-8585 (Japan); Yuzawa, Hayato; Horigome, Toshio [Institute for Molecular Science, Myodaiji, Okazaki 444-8585 (Japan)

2014-10-15T23:59:59.000Z

54

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

SciTech Connect (OSTI)

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

55

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

56

Theoretical standards in x-ray spectroscopies  

SciTech Connect (OSTI)

We propose to extend our state-of-the-art, ab initio XAFS (X-ray absorption fine structure) codes, FEFF. Our current work has been highly successful in achieving accurate, user-friendly XAFS standards, exceeding the performance of both tabulated standards and other codes by a considerable margin. We now propose to add the capability to treat more complex materials. This includes multiple-scattering, polarization dependence, an approximate treatment of XANES (x-ray absorption near edge structure), and other improvements. We also plan to adapt FEFF to other spectroscopies, e.g. photoelectron diffraction (PD) and diffraction anomalous fine structure (DAFS).

Not Available

1992-01-01T23:59:59.000Z

57

Sulfur K-edge X-ray absorption spectroscopy as an experimental probe for S-nitroso proteins  

SciTech Connect (OSTI)

X-ray absorption spectroscopy at the sulfur K-edge (2.4-2.6 keV) provides a sensitive and specific technique to identify S-nitroso compounds, which have significance in nitric oxide-based cell signaling. Unique spectral features clearly distinguish the S-nitroso-form of a cysteine residue from the sulfhydryl-form or from a methionine thioether. Comparison of the sulfur K-edge spectra of thiolate, thiol, thioether, and S-nitroso thiolate compounds indicates high sensitivity of energy positions and intensities of XAS pre-edge features as determined by the electronic environment of the sulfur absorber. A new experimental setup is being developed for reaching the in vivo concentration range of S-nitroso thiol levels in biological samples.

Szilagyi, Robert K. [Department of Chemistry and Biochemistry, Montana State University, Bozeman, MT 59717 (United States)]. E-mail: Szilagyi@Montana.EDU; Schwab, David E. [Department of Chemistry and Biochemistry, Montana State University, Bozeman, MT 59717 (United States)

2005-04-29T23:59:59.000Z

58

In-situ X-ray absorption spectroscopy analysis of capacity fade in nanoscale-LiCoO{sub 2}  

SciTech Connect (OSTI)

The local structure of nanoscale (?10–40 nm) LiCoO{sub 2} is monitored during electrochemical cycling utilizing in-situ X-ray absorption spectroscopy (XAS). The high surface area of the LiCoO{sub 2} nanoparticles not only enhances capacity fade, but also provides a large signal from the particle surface relative to the bulk. Changes in the nanoscale LiCoO{sub 2} metal-oxide bond lengths, structural disorder, and chemical state are tracked during cycling by adapting the delta mu (??) technique in complement with comprehensive extended X-ray absorption fine structure (EXAFS) modeling. For the first time, we use a ?? EXAFS method, and by comparison of the difference EXAFS spectra, extrapolate significant coordination changes and reduction of cobalt species with cycling. This combined approach suggests Li–Co site exchange at the surface of the nanoscale LiCoO{sub 2} as a likely factor in the capacity fade and irreversible losses in practical, microscale LiCoO{sub 2}. - Graphical abstract: Electrochemical cycling of Li-ion batteries has strong impact on the structure and integrity of the cathode active material particularly near the surface/electrolyte interface. In developing a new method, we have used in-situ X-ray absorption spectroscopy during electrochemical cycling of nanoscale LiCoO{sub 2} to track changes during charge and discharge and between subsequent cycles. Using difference spectra, several small changes in Co-O bond length, Co-O and Co-Co coordination, and site exchange between Co and Li sites can be tracked. These methods show promise as a new technique to better understand processes which lead to capacity fade and loss in Li-ion batteries. - Highlights: • A new method is developed to understand capacity fade in Li-ion battery cathodes. • Structural changes are tracked during Li intercalation/deintercalation of LiCoO{sub 2}. • Surface structural changes are emphasized using nanoscale-LiCoO{sub 2} and difference spectra. • Full multiple scattering calculations are used to support ?? analysis.

Patridge, Christopher J. [NRC/NRL Cooperative Research Associate, U.S. Naval Research Laboratory, Washington, DC 20375 (United States); Love, Corey T., E-mail: corey.love@nrl.navy.mil [Chemistry Division, Code 6113, U.S. Naval Research Laboratory, Washington, DC 20375 (United States); Swider-Lyons, Karen E. [Chemistry Division, Code 6113, U.S. Naval Research Laboratory, Washington, DC 20375 (United States); Twigg, Mark E. [Electronics Science and Technology Division, Code 6812, U.S. Naval Research Laboratory, Washington, DC 20375 (United States); Ramaker, David E. [Chemistry Division, Code 6189, U.S. Naval Research laboratory, Washington, DC 20375 (United States)

2013-07-15T23:59:59.000Z

59

X-ray absorption spectroscopy elucidates the impact of structural disorder on electron mobility in amorphous zinc-tin-oxide thin films  

SciTech Connect (OSTI)

We investigate the correlation between the atomic structures of amorphous zinc-tin-oxide (a-ZTO) thin films grown by atomic layer deposition (ALD) and their electronic transport properties. We perform synchrotron-based X-ray absorption spectroscopy at the K-edges of Zn and Sn with varying [Zn]/[Sn] compositions in a-ZTO thin films. In extended X-ray absorption fine structure (EXAFS) measurements, signal attenuation from higher-order shells confirms the amorphous structure of a-ZTO thin films. Both quantitative EXAFS modeling and X-ray absorption near edge spectroscopy (XANES) reveal that structural disorder around Zn atoms increases with increasing [Sn]. Field- and Hall-effect mobilities are observed to decrease with increasing structural disorder around Zn atoms, suggesting that the degradation in electron mobility may be correlated with structural changes.

Siah, Sin Cheng, E-mail: siahsincheng@gmail.com, E-mail: buonassisi@mit.edu; Lee, Yun Seog; Buonassisi, Tonio, E-mail: siahsincheng@gmail.com, E-mail: buonassisi@mit.edu [Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Lee, Sang Woon; Gordon, Roy G. [Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts 02138 (United States); Heo, Jaeyeong [Department of Materials Science and Engineering, Chonnam National University, Gwangju 500-757 (Korea, Republic of); Shibata, Tomohiro; Segre, Carlo U. [Physics Department and CSRRI, Illinois Institute of Technology, Chicago, Illinois 606016 (United States)

2014-06-16T23:59:59.000Z

60

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

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

Near-infrared photoluminescence and ligand K-edge x-ray absorption spectroscopies of AnO2Cl42-(An:u, NP, Pu)  

SciTech Connect (OSTI)

We have used photoluminescence and X-ray absorption spectroscopies to investigate electronic structures and metal-ligand bonding of a series of An02CI/ ' (An = U, Np, Pu) compounds. Specifically, we will discuss time-resolved near-infrared emission spectra of crystalline Cs2U(An)02C14 (An = Np and Pu) both at 23 K and 75 K, as well as chlorine Kedge X-ray absorption spectra ofCs2An02CI4 (An = U, Np).

Wilkerson, Marianne P [Los Alamos National Laboratory; Berg, John M [Los Alamos National Laboratory; Clark, David L [Los Alamos National Laboratory; Conradson, Steven D [Los Alamos National Laboratory; Hobart, David E [Los Alamos National Laboratory; Kozimor, Stosh A [Los Alamos National Laboratory; Scott, Brian L [Los Alamos National Laboratory

2008-01-01T23:59:59.000Z

62

Start | View At a Glance | Author Index 220-1 Kinetics of Rapid Redox Processes at the Mineral/Water Interface Using Quick-Scanning X-Ray Absorption Spectroscopy  

E-Print Network [OSTI]

at the Mineral/Water Interface Using Quick-Scanning X-Ray Absorption Spectroscopy (Q-XAS). See more from-situ synchrotron-based technique, quick scanning X-ray absorption spectroscopy (Q-XAS), at sub-second time scales

Sparks, Donald L.

63

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

SciTech Connect (OSTI)

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

64

X-ray absorption spectroscopy study of the local structure of heavy metal ions incorporated into electrodeposited nickel oxide films  

SciTech Connect (OSTI)

The incorporation of heavy metal ions into simulated corrosion films has been investigated using spectroscopic and electrochemical techniques. The films were formed by electrodeposition of the appropriate oxide (hydroxide) onto a graphite substrate. Synchrotron X-ray absorption spectroscopy (XAS) was used to determine the structure and composition of the host oxide film, as well as the local structure of the impurity ion. Results on the incorporation of Ce and Sr into surface films of Ni(OH){sub 2} and NiOOH are reported. Cathodically deposited Ni(OH){sub 2} was found to be mainly in the alpha form while anodically prepared NiOOH showed the presence of Ni{sup +2} and Ni{sup +4}. Cerium incorporated into Ni(OH){sub 2} exists as mixed Ce{sup +3} and Ce{sup +4} phases; a Ce{sup +4} species was found when Ce was codeposited with NiOOH. The structure of the Ce{sup +4} phase in anodic films appears similar to a Ce(OH){sub 4} standard. However, XAS, X-ray diffraction, and laser Raman measurements indicate that the latter chemical formulation is probably incorrect and that the material is really a disordered form of hydrous cerium oxide. The local structure of this material is similar to CeO{sub 2} but has much higher structural disorder. The significance of this finding on the question of the structure of Ce-based corrosion inhibitors in aluminum oxide films is pointed out. Moreover, the authors found it possible to form pure Ce oxide (hydroxide) films on graphite by both cathodic and anodic electrodeposition; their structures have also been elucidated. Strontium incorporated into nickel oxide films consists of Sr{sup +2} which is coordinated to oxygen atoms and is likely to exist as small domains of coprecipitated material.

Balasubramanian, M.; Melendres, C.A. [Argonne National Lab., IL (United States). Chemical Technology Div.] [Argonne National Lab., IL (United States). Chemical Technology Div.; Mansour, A.N. [Naval Surface Warfare Center, Bethesda, MD (United States). Carderock Div.] [Naval Surface Warfare Center, Bethesda, MD (United States). Carderock Div.

1999-02-01T23:59:59.000Z

65

Time-resolved x-ray absorption spectroscopy of photoinduced insulator-metal transition in a colossal magnetoresistive manganite  

SciTech Connect (OSTI)

We studied the ultrafast insulator-metal transition in a manganite by means of picosecond X-ray absorption at the O K- and Mn L-edges, probing photoinduced changes in O-2p and Mn-3d electronic states near the Fermi level.

Rini, M.; Tobey, R.; Wall, S.; Zhu, Y.; Tomioka, Y.; Tokura, Y.; Cavalleri, A.; Schoenlein, R.W.

2008-08-01T23:59:59.000Z

66

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

67

An x-ray absorption near-edge spectroscopy study of the oxidation state of chromium in electrodeposited oxide films.  

SciTech Connect (OSTI)

The oxidation state of chromium incorporated into simulated corrosion films of nickel has been investigated using the technique of 'in situ' X-ray Absorption Near-Edge Spectroscopy (XANES). The films were prepared by electrochemical deposition of the appropriate oxide (hydroxide) onto a graphite substrate. Cathodic deposition from a 0.01 M Cr(NO{sub 3}){sub 3} solution at constant current results in a Cr{sup 3+} oxide (hydroxide) film. Deposition from a 0.01 M K{sub 2}CrO{sub 4} solution produces a film which is predominantly Cr{sup 3+} but with some Cr{sup 6+}. This material is air-sensitive and the ratio of Cr{sup 6+} to Cr{sup 3+} increases with time of exposure to ambient. Cathodic codeposition of Cr{sup 3+} with nickel hydroxide from Cr(NO{sub 3}){sub 3} solution results in a film with chromium in the 3+ oxidation state. On the other hand, cathodic codeposition from a Cr{sup 6+} solution of K{sub 2}CrO{sub 4} with nickel hydroxide leads to a film containing Cr{sup 6+}.

Balasubramanian, M.; Melendres, C. A.; Chemical Engineering

1999-01-01T23:59:59.000Z

68

Development of Palladium L-Edge X-Ray Absorption Spectroscopy And Its Application for Chloropalladium Complexes  

SciTech Connect (OSTI)

X-ray absorption spectroscopy (XAS) is a synchrotron-based experimental technique that provides information about geometric and electronic structures of transition metal complexes. Combination of metal L-edge and ligand K-edge XAS has the potential to define the complete experimental ground state electronic structures for metal complexes with unoccupied d manifolds. We developed a quantitative treatment for Pd L-edge spectroscopy on the basis of the well-established chlorine K-edge XAS for a series of chloropalladium complexes that are pre-catalysts in various organic transformations. We found that Pd-Cl bonds are highly covalent, such as 24 {+-} 2%, 34 {+-} 3%, and 48 {+-} 4% chloride 3p character for each Pd-Cl bond in [PdCl{sub 4}]{sup 2-}, [PdCl{sub 6}]{sup 2-}, and PdCl{sub 2}, respectively. Pd(2p {yields} 4d) transition dipole integrals of 20.8 (SSRL)/16.9 (ALS) eV and 14.1 (SSRL)/11.9 (ALS) eV were determined using various combinations of L-edges for Pd(II) and Pd(IV), respectively. Application of metal-ligand covalency and transition dipole integrals were demonstrated for the example of bridging chloride ligands in PdCl{sub 2}. Our work lays the foundation for extending the quantitative treatment to other catalytically important ligands, such as phosphine, phosphite, olefin, amine, and alkyl in order to correlate the electronic structures of palladium complexes with their catalytic activity.

Boysen, R.B.; Szilagyi, R.K.

2009-05-12T23:59:59.000Z

69

Quick extended x-ray absorption fine structure instrument with millisecond time scale, optimized for in situ applications  

E-Print Network [OSTI]

Quick extended x-ray absorption fine structure instrument with millisecond time scale, optimized of quick extended x-ray absorption fine structure QEXAFS and quick x-ray absorption near edge structure- tion spectroscopy XAS was developed in energy dispersive and quick extended x-ray absorption fine

Sparks, Donald L.

70

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

SciTech Connect (OSTI)

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

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

2011-09-15T23:59:59.000Z

71

Ultrafast extended x-ray absorption fine structure ,,EXAFS...--theoretical considerations  

E-Print Network [OSTI]

13­20 to generate ultrafast x-ray pulses, however, the prospect of ultrafast EXAFS seems encouragingUltrafast extended x-ray absorption fine structure ,,EXAFS...--theoretical considerations Frank L by the recent experimental demonstration of ultrafast x-ray absorption spectroscopy, we present a framework

Cao, Jianshu

72

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

SciTech Connect (OSTI)

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

73

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

74

Sapphire analyzers for high-resolution x-ray spectroscopy.  

SciTech Connect (OSTI)

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

75

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.

76

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

SciTech Connect (OSTI)

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

77

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

E-Print Network [OSTI]

I present high-resolution X-ray grating spectroscopy of neutron stars in low-mass X-ray binaries (LMXBs) using instruments onboard the Chandra X-ray Observatory and the X-ray Multi-Mirror Mission (XMM-Newton). The first ...

Juett, Adrienne Marie, 1976-

2004-01-01T23:59:59.000Z

78

Soft-x-ray spectroscopy study of nanoscale materials  

SciTech Connect (OSTI)

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

Guo, J.-H.

2005-07-30T23:59:59.000Z

79

Cation distribution in Ni{sub 1?x}Zn{sub x}Fe{sub 2}O{sub 4} using X-ray absorption spectroscopy  

SciTech Connect (OSTI)

Spinel ferrite samples of Ni{sub 1?x}Zn{sub x}Fe{sub 2}O{sub 4} (for x=0.2, 0.4, 0.5, 0.6 and 0.8) nanoparticles prepared by a novel chemical synthesis method have been characterized by X-ray Absorption Spectroscopy (XAS) technique to investigate the distribution of cations in the unit cell. XANES region clearly shows that as Ni concentration increases, the pre-edge feature, which is a characteristic of tetrahedral coordination of Fe, is enhanced. A quantitative determination of the relative occupancy of iron cation in the octahedral and tetrahedral sites of the spinel structure was obtained from EXAFS data analysis. It has been found that as atomic fraction of Ni is increased from 0.2 to 0.8, Fe occupancy at tetrahedral to octahedral sites is increased from 13:87 and to 39:61.

Yadav, A. K., E-mail: akyadav@barc.gov.in; Jha, S. N.; Bhattacharyya, D.; Sahoo, N. K. [Atomic and Molecular Physics Division, Bhabha Atomic Research Centre, Mumbai - 400094 (India); Jadhav, J.; Biswas, S. [Department of Physics, The LNM Institute of Information Technology, Jaipur-302031 (India)

2014-04-24T23:59:59.000Z

80

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

SciTech Connect (OSTI)

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

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 spectroscopy of manganese clusters  

SciTech Connect (OSTI)

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

82

Statistically meaningful data on the chemical state of ironprecipitates in processed multicrystalline silicon usingsynchrotron-based X-ray absorption spectroscopy  

SciTech Connect (OSTI)

X-ray fluorescence microscopy (mu-XRF), x-ray beam induced current (XBIC), and x-ray absorption spectromicroscopy (mu-XAS) were performed on fully-processed Bay Six cast multicrystalline silicon and aluminum-gettered AstroPower Silicon-Film(TM) sheet material. Over ten iron precipitates--predominantly of iron silicide--were identified at low lifetime regions in both materials, both at grain boundaries and intragranular defects identified by XBIC. In addition, large (micron-sized) particles containing oxidized iron and other impurities (Ca, Cr, Mn) were found in BaySix material. The smaller iron silicide precipitates were more numerous and spatially distributed than their larger oxidized iron counterparts, and thus deemed more detrimental to minority carrier diffusion length.

Buonassisi, T.; Heuer, M.; Istratov, A.A.; Weber, E.R.; Cai, Z.; Lai, B.; Marcus, M.; Lu, J.; Rozgonyi, G.; Schindler, R.; Jonczyk, R.; Rand, J.

2004-11-08T23:59:59.000Z

83

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

84

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

85

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

SciTech Connect (OSTI)

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

86

Role of defects in BiFeO{sub 3} multiferroic films and their local electronic structure by x-ray absorption spectroscopy  

SciTech Connect (OSTI)

Present study reports the role of defects in the electrical transport in BiFeO{sub 3} (BFO) multiferroic films and its local electronic structure investigated by near-edge X-ray absorption fine structure. Defects created by high energy 200?MeV Ag{sup +15} ion irradiation with a fluence of ?5?×?10{sup 11} ions/cm{sup 2} results in the increase in structural strain and reduction in the mobility of charge carriers and enhancement in resistive (I-V) and polarization (P-E) switching behaviour. At higher fluence of ?5?×?10{sup 12} ions/cm{sup 2}, there is a release in the structural strain due to local annealing effect, resulting in an increase in the mobility of charge carriers, which are released from oxygen vacancies and hence suppression in resistive and polarization switching. Near-edge X-ray absorption fine structure studies at Fe L{sub 3,2}- and O K-edges show a significant change in the spectral features suggesting the modifications in the local electronic structure responsible for changes in the intrinsic magnetic moment and electrical transport properties of BFO.

Ravalia, Ashish; Vagadia, Megha; Solanki, P. S.; Shah, N. A.; Kuberkar, D. G., E-mail: dgkuberkar@rediffmail.com [Department of Physics, Saurashtra University, Rajkot 360 005 (India); Gautam, S.; Chae, K. H. [Nano Material Analysis Centre, Korean Institute of Science and Technology, Seoul 136-79 (Korea, Republic of); Asokan, K. [Inter University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi 110 067 (India)

2014-10-21T23:59:59.000Z

87

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.

88

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...

89

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 (OSTI)

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

90

X-ray absorption in distant type II QSOs  

E-Print Network [OSTI]

We present the results of the X-ray spectral analysis of an XMM-Newton-selected type II QSO sample with z>0.5 and 0.5-10 keV flux of 0.3-33 x 10^{-14} erg/s/cm^2. The distribution of absorbing column densities in type II QSOs is investigated and the dependence of absorption on X-ray luminosity and redshift is studied. We inspected 51 spectroscopically classified type II QSO candidates from the XMM-Newton Marano field survey, the XMM-Newton-2dF wide angle survey (XWAS), and the AXIS survey to set-up a well-defined sample with secure optical type II identifications. Fourteen type II QSOs were classified and an X-ray spectral analysis performed. Since most of our sources have only ~40 X-ray counts (PN-detector), we carefully studied the fit results of the simulated X-ray spectra as a function of fit statistic and binning method. We determined that fitting the spectra with the Cash-statistic and a binning of minimum one count per bin recovers the input values of the simulated X-ray spectra best. Above 100 PN counts, the free fits of the spectrum's slope and absorbing hydrogen column density are reliable. We find only moderate absorption (N_H=(2-10) x 10^22 cm^-2) and no obvious trends with redshift and intrinsic X-ray luminosity. In a few cases a Compton-thick absorber cannot be excluded. Two type II objects with no X-ray absorption were discovered. We find no evidence for an intrinsic separation between type II AGN and high X-ray luminosity type II QSO in terms of absorption. The stacked X-ray spectrum of our 14 type II QSOs shows no iron K-alpha line. In contrast, the stack of the 8 type II AGN reveals a very prominent iron K-alpha line at an energy of ~ 6.6 keV and an EW ~ 2 keV.

M. Krumpe; G. Lamer; A. Corral; A. D. Schwope; F. J. Carrera; X. Barcons; M. Page; S. Mateos; J. A. Tedds; M. G. Watson

2008-03-10T23:59:59.000Z

91

GEOC Sunday, March 21, 2010 47 -Speciation and release kinetics of cadmium and zinc in paddy soils: Application of X-ray absorption  

E-Print Network [OSTI]

: Application of X-ray absorption spectroscopy (XAS) Saengdao Khaokaew, Rufus L Chaney, PhD Matt Ginder kinetics, which is the aim of this research. X-ray absorption spectroscopy (XAS) was used to investigate Cd-ray absorption fine structure (EXAFS) spectroscopic data indicates that CdCO3 and Cd-humic complexes

Sparks, Donald L.

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...  

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

X-ray absorption in distant type II QSOs  

E-Print Network [OSTI]

We present the results of the X-ray spectral analysis of an XMM-Newton-selected type II QSO sample with z>0.5 and 0.5-10 keV flux of 0.3-33 x 10^{-14} erg/s/cm^2. The distribution of absorbing column densities in type II QSOs is investigated and the dependence of absorption on X-ray luminosity and redshift is studied. We inspected 51 spectroscopically classified type II QSO candidates from the XMM-Newton Marano field survey, the XMM-Newton-2dF wide angle survey (XWAS), and the AXIS survey to set-up a well-defined sample with secure optical type II identifications. Fourteen type II QSOs were classified and an X-ray spectral analysis performed. Since most of our sources have only ~40 X-ray counts (PN-detector), we carefully studied the fit results of the simulated X-ray spectra as a function of fit statistic and binning method. We determined that fitting the spectra with the Cash-statistic and a binning of minimum one count per bin recovers the input values of the simulated X-ray spectra best. Above 100 PN coun...

Krumpe, M; Corral, A; Schwope, A D; Carrera, F J; Barcons, X; Page, M; Mateos, S; Tedds, J A; Watson, M G

2008-01-01T23:59:59.000Z

95

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

SciTech Connect (OSTI)

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

96

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

97

Cu K-edge X-ray Absorption Spectroscopy Reveals Differential Copper Coordimation Within Amyloid-beta Oligomers Compared to Amyloid-beta Monomers  

SciTech Connect (OSTI)

The fatal neurodegenerative disorder Alzheimer's disease (AD) has been linked to the formation of soluble neurotoxic oligomers of amyloid-{beta} (A{beta}) peptides. These peptides have high affinities for copper cations. Despite their potential importance in AD neurodegeneration few studies have focused on probing the Cu{sup 2+/1+} coordination environment within A{beta} oligomers. Herein we present a Cu K-edge X-ray absorption spectroscopic study probing the copper-coordination environment within oligomers of A{beta}(42) (sequence: DAEFRHDSGYEVHHQKLVFFAEDVGSNKGAIIGLMVGGVVIA). We find that the Cu{sup 2+} cation is contained within a square planar mixed N/O ligand environment within A{beta}(42) oligomers, which is similar to the copper coordination environment of the monomeric forms of {l_brace}Cu{sup II}A{beta}(40){r_brace} and {l_brace}Cu{sup II}A{beta}(16){r_brace}. Reduction of the Cu{sup 2+} cation within the A{beta}(42) oligomers to Cu{sup 1+} yields a highly dioxygen sensitive copper-species that contains Cu{sup 1+} in a tetrahedral coordination geometry. This can be contrasted with monomers of {l_brace}Cu{sup I}A{beta}(40){r_brace} and {l_brace}Cu{sup I}A{beta}(16){r_brace}, which contain copper in a dioxygen inert linear bis-histidine ligand environment [Shearer and Szalai, J. Am. Chem. Soc., 2008, 130, 17826]. The biological implications of these findings are discussed.

J Shearer; P Callan; T Tran; V Szalai

2011-12-31T23:59:59.000Z

98

Chemical Shifts in X-ray and Photo-Electron Spectroscopy: A Historical review  

E-Print Network [OSTI]

Chemical Shifts in X-ray and Photo-Electron Spectroscopy: A Historical review Ingvar Lindgren 1 Introduction 2 2 Chemical shift in X-ray spectroscopy 2 2.1 Discovery of the chemical shift in X-ray spectroscopy . . . . . . . . . . . . . 3 2.2 Interpretation of the chemical shift in X-ray spectroscopy

Lindgren, Ingvar

99

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

SciTech Connect (OSTI)

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

100

Extended Xray 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 xrays are absorbed by an atom at energies near  

E-Print Network [OSTI]

's xray absorption probability due to the chemical and physical state of the atom · Especially sensitiveExtended Xray 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 xrays are absorbed by an atom

Ohta, Shigemi

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

SMB, X-ray Emission Spectroscopy  

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

AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr MayAtmosphericNuclear Security Administration the1 -the Mid-Infrared0 ResourceAwards SAGE Awards ,#2446Small Angle X-RayEmission

102

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

103

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

104

Theoretical standards in x-ray spectroscopies. Annual progress report, 1991--1992  

SciTech Connect (OSTI)

We propose to extend our state-of-the-art, ab initio XAFS (X-ray absorption fine structure) codes, FEFF. Our current work has been highly successful in achieving accurate, user-friendly XAFS standards, exceeding the performance of both tabulated standards and other codes by a considerable margin. We now propose to add the capability to treat more complex materials. This includes multiple-scattering, polarization dependence, an approximate treatment of XANES (x-ray absorption near edge structure), and other improvements. We also plan to adapt FEFF to other spectroscopies, e.g. photoelectron diffraction (PD) and diffraction anomalous fine structure (DAFS).

Not Available

1992-09-01T23:59:59.000Z

105

NSLS (National Synchrotron Light Source) X-19A beamline performance for x-ray absorption measurements  

SciTech Connect (OSTI)

Characterization of the X-19A beamline at the National Synchrotron Light Source (NSLS) is described. The beamline is designed for high resolution x-ray absorption spectroscopy over a wide energy range. All of the beamline optical components are compatible with ultrahigh vacuum (UHV) operation. This permits measurements to be made in a window-less mode, thereby facilitating lower energy (<4 KeV) studies. To upgrade the beamline performance, several possible improvements in instrumentation and practice are discussed to increase photon statistics with an optimum energy resolution, while decreasing the harmonic contamination and noise level. A special effort has been made to improve the stability and UHV compatibility of the monochromator system. Initial x-ray absorption results demonstrate the capabilities of this beamline for x-ray absorption studies of low Z elements (e.g. S) in highly dilute systems. The future use of this beamline for carrying out various x-ray absorption experiments is presented. 10 refs., 4 figs.

Yang, C.Y.; Penner-Hahn, J.E.; Stefan, P.M. (Michigan Univ., Ann Arbor, MI (USA). Dept. of Chemistry; Brookhaven National Lab., Upton, NY (USA))

1989-01-01T23:59:59.000Z

106

X-RAY ABSORPTION OF HIGH-REDSHIFT QUASARS  

SciTech Connect (OSTI)

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

High-resolution X-ray spectroscopy of Theta Car  

E-Print Network [OSTI]

Context : The peculiar hot star Theta Car in the open cluster IC2602 is a blue straggler as well as a single-line binary of short period (2.2d). Aims : Its high-energy properties are not well known, though X-rays can provide useful constraints on the energetic processes at work in binaries as well as in peculiar, single objects. Methods : We present the analysis of a 50ks exposure taken with the XMM-Newton observatory. It provides medium as well as high-resolution spectroscopy. Results : Our high-resolution spectroscopy analysis reveals a very soft spectrum with multiple temperature components (1--6MK) and an X-ray flux slightly below the `canonical' value (log[L_X(0.1-10.)/L_{BOL}] ~ -7). The X-ray lines appear surprisingly narrow and unshifted, reminiscent of those of beta Cru and tau Sco. Their relative intensities confirm the anomalous abundances detected in the optical domain (C strongly depleted, N strongly enriched, O slightly depleted). In addition, the X-ray data favor a slight depletion in neon and iron, but they are less conclusive for the magnesium abundance (solar-like?). While no significant changes occur during the XMM-Newton observation, variability in the X-ray domain is detected on the long-term range. The formation radius of the X-ray emission is loosely constrained to <5 R_sol, which allows for a range of models (wind-shock, corona, magnetic confinement,...) though not all of them can be reconciled with the softness of the spectrum and the narrowness of the lines.

Yael Naze; Gregor Rauw

2008-08-25T23:59:59.000Z

108

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

SciTech Connect (OSTI)

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

109

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

SciTech Connect (OSTI)

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

110

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

111

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

SciTech Connect (OSTI)

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

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

2010-12-01T23:59:59.000Z

112

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

113

A doubly curved elliptical crystal spectrometer for the study of localized x-ray absorption in hot plasmas  

SciTech Connect (OSTI)

X-ray absorption spectroscopy is a powerful tool for the diagnosis of plasmas over a wide range of both temperature and density. However, such a measurement is often limited to probing plasmas with temperatures well below that of the x-ray source in order to avoid object plasma emission lines from obscuring important features of the absorption spectrum. This has excluded many plasmas from being investigated by this technique. We have developed an x-ray spectrometer that provides the ability to record absorption spectra from higher temperature plasmas than the usual approach allows without the risk of data contamination by line radiation emitted by the plasma under study. This is accomplished using a doubly curved mica crystal which is bent both elliptically and cylindrically. We present here the foundational work in the design and development of this spectrometer along with initial results obtained with an aluminum x-pinch as the object plasma.

Cahill, Adam D., E-mail: adc87@cornell.edu; Hoyt, Cad L.; Pikuz, Sergei A.; Shelkovenko, Tania; Hammer, David A. [Cornell University, Electrical and Computer Engineering, Ithaca, NY 14853 (United States)

2014-10-15T23:59:59.000Z

114

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

SciTech Connect (OSTI)

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

115

Boron Doped diamond films as electron donors in photovoltaics: An X-ray absorption and hard X-ray photoemission study  

SciTech Connect (OSTI)

Highly boron-doped diamond films are investigated for their potential as transparent electron donors in solar cells. Specifically, the valence band offset between a diamond film (as electron donor) and Cu(In,Ga)Se{sub 2} (CIGS) as light absorber is determined by a combination of soft X-ray absorption spectroscopy and hard X-ray photoelectron spectroscopy, which is more depth-penetrating than standard soft X-ray photoelectron spectroscopy. In addition, a theoretical analysis of the valence band is performed, based on GW quasiparticle band calculations. The valence band offset is found to be small: VBO?=?VBM{sub CIGS} – VBM{sub diamond}?=?0.3?eV?±?0.1?eV at the CIGS/Diamond interface and 0.0?eV?±?0.1?eV from CIGS to bulk diamond. These results provide a promising starting point for optimizing the band offset by choosing absorber materials with a slightly lower valence band maximum.

Kapilashrami, M.; Zegkinoglou, I. [Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Department of Physics, University of Wisconsin Madison, Madison, Wisconsin 53706 (United States); Conti, G.; Nemšák, S.; Conlon, C. S.; Fadley, C. S. [Department of Physics, University of California, Davis, California 95616 (United States); Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Törndahl, T.; Fjällström, V. [Ångström Solar Center, Uppsala University, Box 534, SE-751 21 Uppsala (Sweden); Lischner, J. [Department of Physics, University of California, Berkeley, California 94720 (United States); Louie, Steven G. [Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Department of Physics, University of California, Berkeley, California 94720 (United States); Hamers, R. J.; Zhang, L. [Department of Chemistry, University of Wisconsin Madison, Madison, Wisconsin 53706 (United States); Guo, J.-H. [Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Himpsel, F. J., E-mail: fhimpsel@wisc.edu [Department of Physics, University of Wisconsin Madison, Madison, Wisconsin 53706 (United States)

2014-10-14T23:59:59.000Z

116

X-ray Absorption Spectroscopy and Density Functional Theory Studies of [(H3buea)FeIII-X]n1 (X= S2-, O2-,OH-): Comparison of Bonding and Hydrogen Bonding in Oxo and Sulfido Complexes  

SciTech Connect (OSTI)

Iron L-edge, iron K-edge, and sulfur K-edge X-ray absorption spectroscopy was performed on a series of compounds [Fe{sup III}H{sub 3}buea(X)]{sup n-} (X = S{sup 2-}, O{sup 2-}, OH{sup -}). The experimentally determined electronic structures were used to correlate to density functional theory calculations. Calculations supported by the data were then used to compare the metal-ligand bonding and to evaluate the effects of H-bonding in Fe{sup III}-O vs Fe{sup III-}S complexes. It was found that the Fe{sup III-}O bond, while less covalent, is stronger than the FeIII-S bond. This dominantly reflects the larger ionic contribution to the Fe{sup III-}O bond. The H-bonding energy (for three H-bonds) was estimated to be -25 kcal/mol for the oxo as compared to -12 kcal/mol for the sulfide ligand. This difference is attributed to the larger charge density on the oxo ligand resulting from the lower covalency of the Fe-O bond. These results were extended to consider an Fe{sup IV-}O complex with the same ligand environment. It was found that hydrogen bonding to Fe{sup IV-}O is less energetically favorable than that to Fe{sup III-}O, which reflects the highly covalent nature of the Fe{sup IV-}O bond.

Dey, Abhishek; Hocking, Rosalie K.; /Stanford U., Chem. Dept.; Larsen, Peter; Borovik, Andrew S.; /Kansas U.; Hodgson, Keith O.; Hedman, Britt; Solomon, Edward I.; /SLAC,

2006-09-27T23:59:59.000Z

117

ON RELATIVISTIC DISK SPECTROSCOPY IN COMPACT OBJECTS WITH X-RAY CCD CAMERAS  

SciTech Connect (OSTI)

X-ray charge-coupled devices (CCDs) are the workhorse detectors of modern X-ray astronomy. Typically covering the 0.3-10.0 keV energy range, CCDs are able to detect photoelectric absorption edges and K shell lines from most abundant metals. New CCDs also offer resolutions of 30-50 (E/{Delta}E), which is sufficient to detect lines in hot plasmas and to resolve many lines shaped by dynamical processes in accretion flows. The spectral capabilities of X-ray CCDs have been particularly important in detecting relativistic emission lines from the inner disks around accreting neutron stars and black holes. One drawback of X-ray CCDs is that spectra can be distorted by photon 'pile-up', wherein two or more photons may be registered as a single event during one frame time. We have conducted a large number of simulations using a statistical model of photon pile-up to assess its impacts on relativistic disk line and continuum spectra from stellar-mass black holes and neutron stars. The simulations cover the range of current X-ray CCD spectrometers and operational modes typically used to observe neutron stars and black holes in X-ray binaries. Our results suggest that severe photon pile-up acts to falsely narrow emission lines, leading to falsely large disk radii and falsely low spin values. In contrast, our simulations suggest that disk continua affected by severe pile-up are measured to have falsely low flux values, leading to falsely small radii and falsely high spin values. The results of these simulations and existing data appear to suggest that relativistic disk spectroscopy is generally robust against pile-up when this effect is modest.

Miller, J. M.; Cackett, E. M. [Department of Astronomy, University of Michigan, 500 Church Street, Ann Arbor, MI 48109 (United States); D'Ai, A. [Dipartimento di Scienze Fisiche ed Astronomiche, Universita di Palermo, Palermo (Italy); Bautz, M. W.; Nowak, M. A. [Kavli Institute for Astrophysics and Space Research, MIT, 77 Massachusetts Avenue, Cambridge, MA 02139 (United States); Bhattacharyya, S. [Department of Astronomy and Astrophysics, Tata Institute of Fundamental Research, Mumbai 400005 (India); Burrows, D. N.; Kennea, J. [Department of Astronomy and Astrophysics, Pennsylvania State University, 525 Davey Lab, College Park, PA 16802 (United States); Fabian, A. C.; Reis, R. C. [Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge, CB3 OHA (United Kingdom); Freyberg, M. J.; Haberl, F. [Max-Planck-Institut fuer extraterrestrische Physik, Giessenbachstrasse, 85748 Garching (Germany); Strohmayer, T. E. [Astrophysics Science Division, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Tsujimoto, M., E-mail: jonmm@umich.ed [Japan Aerospace Exploration Agency, Institute of Space and Astronomical Sciences, 3-1-1 Yoshino-dai, Sagamihara, Kanagawa 229-8510 (Japan)

2010-12-01T23:59:59.000Z

118

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

119

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

120

Chandra High Resolution X-ray Spectroscopy of AM Her  

E-Print Network [OSTI]

We present the results of high resolution spectroscopy of the prototype polar AM Herculis observed with Chandra High Energy Transmission Grating. The X-ray spectrum contains hydrogen-like and helium-like lines of Fe, S, Si, Mg, Ne and O with several Fe L-shell emission lines. The forbidden lines in the spectrum are generally weak whereas the hydrogen-like lines are stronger suggesting that emission from a multi-temperature, collisionally ionized plasma dominates. The helium-like line flux ratios yield a plasma temperature of 2 MK and a plasma density 1 - 9 x10^12 cm^-3, whereas the line flux ratio of Fe XXVI to Fe XXV gives an ionization temperature of 12.4 +1.1 -1.4 keV. We present the differential emission measure distribution of AM Her whose shape is consistent with the volume emission measure obtained by multi-temperature APEC model. The multi-temperature plasma model fit to the average X-ray spectrum indicates the mass of the white dwarf to be ~1.15 M_sun. From phase resolved spectroscopy, we find the line centers of Mg XII, S XVI, resonance line of Fe XXV, and Fe XXVI emission modulated by a few hundred to 1000 km/s from the theoretically expected values indicating bulk motion of ionized matter in the accretion column of AM Her. The observed velocities of Fe XXVI ions are close to the expected shock velocity for a 0.6 M_sun white dwarf. The observed velocity modulation is consistent with that expected from a single pole accreting binary system.

V. Girish; V. R. Rana; K. P. Singh

2007-02-14T23:59:59.000Z

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

Where Water is Oxidized to Dioxygen: Structure of the Photosynthetic Mn4Ca Cluster from X-ray Spectroscopy  

SciTech Connect (OSTI)

Light-driven oxidation of water to dioxygen in plants, algae and cyanobacteria iscatalyzed within photosystem II (PS II) by a Mn4Ca cluster. Although the cluster has been studied by many different methods, the structure and the mechanism have remained elusive. X-ray absorption and emission spectroscopy and EXAFS studies have been particularly useful in probing the electronic and geometric structure, and the mechanism of the water oxidation reaction. Recent progress, reviewed here, includes polarized X-ray absorption spectroscopy measurements of PS II single crystals. Analysis of those results has constrained the Mn4Ca cluster geometry to a setof three similar high-resolution structures. The structure of the cluster from the present study is unlike either the 3.0 or 3.5 Angstrom-resolution X-ray structures or other previously proposed models. The differences between the models derived from X-rayspectroscopy and crystallography are predominantly because of damage to the Mn4Ca cluster by X-rays under the conditions used for structure determination by X-ray crystallography. X-ray spectroscopy studies are also used for studying the changes in the structure of the Mn4Ca catalytic center as it cycles through the five intermediate states known as the Si-states (i=0-4). The electronic structure of the Mn4Ca cluster has been studied more recently using resonant inelastic X-ray scattering spectroscopy (RIXS), in addition to the earlier X-ray absorption and emission spectroscopy methods. These studies are revealing that the assignment of formaloxidation states is overly simplistic. A more accurate description should consider the charge density on the Mn atoms that includes the covalency of the bonds and delocalization of the charge over the cluster. The geometric and electronic structure of the Mn4Ca cluster in the S-states derived from X-ray spectroscopy are leading to a detailed understanding of the mechanism of the O-O bond formation during the photosynthetic water splitting process.

Yano, Junko; Yano, Junko; Yachandra, Vittal K.

2007-10-24T23:59:59.000Z

122

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

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

123

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

SciTech Connect (OSTI)

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

124

WEAK HARD X-RAY EMISSION FROM TWO BROAD ABSORPTION LINE QUASARS OBSERVED WITH NuSTAR: COMPTON-THICK ABSORPTION OR INTRINSIC X-RAY WEAKNESS?  

SciTech Connect (OSTI)

We present Nuclear Spectroscopic Telescope Array (NuSTAR) hard X-ray observations of two X-ray weak broad absorption line (BAL) quasars, PG 1004+130 (radio loud) and PG 1700+518 (radio quiet). Many BAL quasars appear X-ray weak, probably due to absorption by the shielding gas between the nucleus and the accretion-disk wind. The two targets are among the optically brightest BAL quasars, yet they are known to be significantly X-ray weak at rest-frame 2-10 keV (16-120 times fainter than typical quasars). We would expect to obtain Almost-Equal-To 400-600 hard X-ray ({approx}> 10 keV) photons with NuSTAR, provided that these photons are not significantly absorbed (N{sub H} {approx}< 10{sup 24} cm{sup -2}). However, both BAL quasars are only detected in the softer NuSTAR bands (e.g., 4-20 keV) but not in its harder bands (e.g., 20-30 keV), suggesting that either the shielding gas is highly Compton-thick or the two targets are intrinsically X-ray weak. We constrain the column densities for both to be N{sub H} Almost-Equal-To 7 Multiplication-Sign 10{sup 24} cm{sup -2} if the weak hard X-ray emission is caused by obscuration from the shielding gas. We discuss a few possibilities for how PG 1004+130 could have Compton-thick shielding gas without strong Fe K{alpha} line emission; dilution from jet-linked X-ray emission is one likely explanation. We also discuss the intrinsic X-ray weakness scenario based on a coronal-quenching model relevant to the shielding gas and disk wind of BAL quasars. Motivated by our NuSTAR results, we perform a Chandra stacking analysis with the Large Bright Quasar Survey BAL quasar sample and place statistical constraints upon the fraction of intrinsically X-ray weak BAL quasars; this fraction is likely 17%-40%.

Luo, B.; Brandt, W. N. [Department of Astronomy and Astrophysics, 525 Davey Lab, The Pennsylvania State University, University Park, PA 16802 (United States); Alexander, D. M.; Hickox, R. [Department of Physics, Durham University, South Road, Durham DH1 3LE (United Kingdom); Harrison, F. A.; Fuerst, F.; Grefenstette, B. W.; Madsen, K. K. [Cahill Center for Astronomy and Astrophysics, California Institute of Technology, Pasadena, CA 91125 (United States); Stern, D. [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States); Bauer, F. E. [Departamento de Astronomia y Astrofisica, Pontificia Universidad Catolica de Chile, Casilla 306, Santiago 22 (Chile); Boggs, S. E.; Craig, W. W. [Space Sciences Laboratory, University of California, Berkeley, CA 94720 (United States); Christensen, F. E. [DTU Space-National Space Institute, Technical University of Denmark, Elektrovej 327, DK-2800 Lyngby (Denmark); Comastri, A. [INAF-Osservatorio Astronomico di Bologna, Via Ranzani 1, I-40127 Bologna (Italy); Fabian, A. C. [Institute of Astronomy, Madingley Road, Cambridge CB3 0HA (United Kingdom); Farrah, D. [Department of Physics, Virginia Tech, Blacksburg, VA 24061 (United States); Fiore, F. [Osservatorio Astronomico di Roma, via Frascati 33, I-00040 Monteporzio Catone (Italy); Hailey, C. J. [Columbia Astrophysics Laboratory, Columbia University, New York, NY 10027 (United States); Matt, G. [Dipartimento di Matematica e Fisica, Universita degli Studi Roma Tre, via della Vasca Navale 84, I-00146 Roma (Italy); Ogle, P. [IPAC, California Institute of Technology, Mail Code 220-6, Pasadena, CA 91125 (United States); and others

2013-08-01T23:59:59.000Z

125

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

126

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

SciTech Connect (OSTI)

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

Tan, G.O.

1993-06-01T23:59:59.000Z

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 (OSTI)

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

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

SciTech Connect (OSTI)

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

129

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

130

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

131

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

SciTech Connect (OSTI)

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

132

In-situ X-ray Photoelectron Spectroscopy of a Catalyst for Artificial...  

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

In-situ X-ray Photoelectron Spectroscopy of a Catalyst for Artificial Photosynthesis Monday, June 30, 2014 Plants and other organisms use a process called photosynthesis to produce...

133

Soft x-ray emission spectroscopy studies of the electronic structure of silicon supersaturated with sulfur  

E-Print Network [OSTI]

We apply soft x-ray emission spectroscopy (XES) to measure the electronic structure of crystalline silicon supersaturated with sulfur (up to 0.7 at. %), a candidate intermediate-band solar cell material. Si L[subscript ...

Sullivan, Joseph Timothy

134

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

135

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

136

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

137

Using in situ X-ray absorption spectroscopy to study the local structure and oxygen ion conduction mechanism in (La{sub 0.6}Sr{sub 0.4})(Co{sub 0.2}Fe{sub 0.8})O{sub 3-{delta}}  

SciTech Connect (OSTI)

To study the local structure and oxygen ion conduction mechanism in (La{sub 0.6}Sr{sub 0.4})(Co{sub 0.2}Fe{sub 0.8})O{sub 3-{delta}} (LSCF) as a function of the oxygen partial pressure (P(O{sub 2})), in situ the Co and Fe K-edge X-ray absorption spectroscopy (XAS) was measured at elevated temperatures of 900 and 1000 K. The reduction of the Co and Fe valence, i.e., the oxygen content (3-{delta}) in LSCF, followed the change of P(O{sub 2}) from 1 to 10{sup -4} atm during{approx}4000 s. The quantitative analysis of the X-ray absorption near edge structure (XANES) and the extended X-ray absorption fine structure (EXAFS) indicated that the Fe valence was higher than the Co valence at oxidative condition ({delta} Almost-Equal-To 0) in LSCF. Whereas the Co valence decreased more than the Fe valence after reduction of P(O{sub 2}) at both 900 and 1000 K. From the relaxation plots of the valence and the oxygen content (3-{delta}) for Co and Fe after changing P(O{sub 2}), we successfully determined D{sub chem} and E{sub a} of an oxygen ion migration around Co and Fe in LSCF. A structural model with and without oxygen vacancies and an oxygen ion conduction mechanism for LSCF are proposed based on these results. - Graphical abstract: A structural model with and without oxygen vacancies, and the oxygen ion conduction mechanism of LSCF were speculated. In other words, oxygen vacancies would form more preferentially around Co than Fe from the results of in situ XAS analysis during reduction, and oxygen ions needs to pass through at the vicinity of Fe from the results of D{sub chem} and E{sub a}. Highlights: Black-Right-Pointing-Pointer Study of the oxygen ion conduction mechanism in (La{sub 0.6}Sr{sub 0.4})(Co{sub 0.2}Fe{sub 0.8})O{sub 3-{delta}} (LSCF). Black-Right-Pointing-Pointer Using in situ X-ray absorption for study of valence and oxygen diffusion coefficient. Black-Right-Pointing-Pointer The oxygen vacancies should be preferentially localized around Co in LSCF. Black-Right-Pointing-Pointer The values of the dynamics parameters for Co and Fe are close to each other.

Itoh, Takanori, E-mail: tknitoh@seimichemical.co.jp [AGC SeimiChemical Co., Ltd., 3-2-10 Chigasaki, Chigasaki City, Kanagawa 253-8585 (Japan); Nakayama, Masanobu [Department of Materials Science and Engineering, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya-city, Aichi 466-8555 (Japan)

2012-08-15T23:59:59.000Z

138

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 (OSTI)

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

139

Confirmation of X-ray Absorption by Warm-hot Intergalactic Medium in the Sculptor Wall  

E-Print Network [OSTI]

In a previous paper, we reported a 3? detection of an absorption line from the warm-hot intergalactic medium (WHIM) using the Chandra and XMM X-ray grating spectra of the blazar H2356-309, the sight line of which intercepts ...

Fang, Taotao

140

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

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

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

SciTech Connect (OSTI)

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

142

Dynamics in shear flow studied by X-ray Photon Correlation Spectroscopy  

E-Print Network [OSTI]

X-ray photon correlation spectroscopy was used to measure the diffusive dynamics of colloidal particles in a shear flow. The results presented here show how the intensity autocorrelation functions measure both the diffusive dynamics of the particles and their flow-induced, convective motion. However, in the limit of low flow/shear rates, it is possible to obtain the diffusive component of the dynamics, which makes the method suitable for the study of the dynamical properties of a large class of complex soft-matter and biological fluids. An important benefit of this experimental strategy over more traditional X-ray methods is the minimization of X-ray induced beam damage. While the method can be applied also for photon correlation spectroscopy in the visible domain, our analysis shows that the experimental conditions under which it is possible to measure the diffusive dynamics are easier to achieve at higher q values (with X-rays).

Sebastian Busch; Torben Haugaard Jensen; Yuriy Chushkin; Andrei Fluerasu

2008-03-19T23:59:59.000Z

143

X-ray spectroscopy of gamma-ray bursts: the path to the progenitor  

E-Print Network [OSTI]

Despite great observational and theoretical effort, the burst progenitor is still a mysterious object. It is generally accepted that one of the best ways to unveil its nature is the study of the properties of the close environment in which the explosion takes place. We discuss the potentiality and feasibility of time resolved X-ray spectroscopy, focusing on the prompt gamma-ray phase. We show that the study of absorption features (or continuum absorption) can reveal the radial structure of the close environment, unaccessible with different techniques. We discuss the detection of absorption in the prompt and afterglow spectra of several bursts, showing how these are consistent with gamma-ray bursts taking place in dense regions. In particular, we show that the radius and density of the surrounding cloud can be measured through the evolution of the column density in the prompt burst phase. The derived cloud properties are similar to those of the star forming cocoons and globules within molecular clouds. We conclude that the burst are likely associated with the final evolutionary stages of massive stars.

Davide Lazzati; Rosalba Perna; Gabriele Ghisellini

2002-01-17T23:59:59.000Z

144

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

145

Solution spectroelectrochemical cell for in situ X-ray absorption fine structure  

SciTech Connect (OSTI)

A purpose-built spectroelectrochemical cell for in situ fluorescence XAFS (X-ray Absorption Fine Structure) measurements of bulk solution species during constant-potential electrolysis is described. The cell performance was demonstrated by the collection of europium L{sub 3}-edge XANES (X-ray Absorption Near Edge Structure) throughout the course of electrolysis of an aqueous solution of EuCl{sub 3}{center_dot}6H{sub 2}O in 1 M H{sub 2}SO{sub 4}. The europium L{sub 3}-edge resonances reported here for the Eu{sup III} and Eu{sup II} ions demonstrate that their 2p{sub 3/2} {yields} 5d electronic transition probabilities are not the same.

Antonio, M.R.; Soderholm, L. [Argonne National Lab., IL (United States). Chemistry Div.; Song, I. [Case Western Reserve Univ., Cleveland, OH (United States)

1995-06-12T23:59:59.000Z

146

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

147

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

148

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

149

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

SciTech Connect (OSTI)

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

150

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.

151

Two-dimensional stimulated resonance Raman spectroscopy of molecules with broadband x-ray pulses  

SciTech Connect (OSTI)

Expressions for the two-dimensional stimulated x-ray Raman spectroscopy (2D-SXRS) signal obtained using attosecond x-ray pulses are derived. The 1D- and 2D-SXRS signals are calculated for trans-N-methyl acetamide (NMA) with broad bandwidth (181 as, 14.2 eV FWHM) pulses tuned to the oxygen and nitrogen K-edges. Crosspeaks in 2D signals reveal electronic Franck-Condon overlaps between valence orbitals and relaxed orbitals in the presence of the core-hole.

Biggs, Jason D.; Zhang Yu; Healion, Daniel; Mukamel, Shaul [Department of Chemistry, University of California, Irvine, California 92697-2025 (United States)

2012-05-07T23:59:59.000Z

152

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

153

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

154

X-ray spectroscopy of the photosynthetic oxygen-evolving complex  

SciTech Connect (OSTI)

Water oxidation to dioxygen in photosynthesis is catalyzed by a Mn4Ca 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, Ken; Yano, Junko; Yachandra, Vittal K

2007-04-05T23:59:59.000Z

155

X-Ray Spectroscopy of the Photosynthetic Oxygen-Evolving Complex  

SciTech Connect (OSTI)

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

156

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

157

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

SciTech Connect (OSTI)

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

158

Stratified Quasar Winds: Integrating X-ray and Infrared Views of Broad Absorption Line Quasars  

E-Print Network [OSTI]

Quasars are notable for the luminous power they emit across decades in frequency from the far-infrared through hard X-rays; emission at different frequencies emerges from physical scales ranging from AUs to parsecs. Each wavelength regime thus offers a different line of sight into the central engine and a separate probe of outflowing material. Therefore, obtaining a complete accounting of the physical characteristics and kinetic power of quasar winds requires a panchromatic approach. X-ray and infrared studies are particularly powerful for covering the range of interesting physical scales and ionization states of the outflow. We present a stratified wind picture based on a synthesis of multiwavelength research programs designed to constrain the nature of mass ejection from radio-quiet quasars. This wind comprises three zones: the highly ionized shielding gas, the UV broad absorption line wind, and the cold dusty outflow. The primary launching mechanism for the wind likely varies in each zone. While radiative acceleration on resonance lines dominates for the UV absorbing wind, the shielding gas may instead be driven by magnetic forces. Ultraviolet continuum radiative pressure, perhaps coupled with magnetic launching, accelerates a dusty outflow that obscures the inner broad line region in unification schemes.

S. C. Gallagher; J. E. Everett

2007-02-07T23:59:59.000Z

159

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

160

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

E-Print Network [OSTI]

Yu Zhang, Daniel Healion, Jason D. Biggs, and Shaul Mukamel Citation: J. Chem. Phys. 138, 144301 be probed by X-ray double-quantum-coherence spectroscopy Yu Zhang, Daniel Healion, Jason D. Biggs, and Shaul

Mukamel, Shaul

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

X-ray photon correlation spectroscopy studies of the dynamics of self-assembling block copolymer structures  

E-Print Network [OSTI]

Several improvements presented to the emerging technique of X-ray Photon Correlation Spectroscopy. These improvements enabled the study of polymer structures, in particular isotropic sponge phases of homo-polymer block ...

Falus, Péter, 1972-

2004-01-01T23:59:59.000Z

162

THE CHANDRA MULTI-WAVELENGTH PROJECT: OPTICAL SPECTROSCOPY AND THE BROADBAND SPECTRAL ENERGY DISTRIBUTIONS OF X-RAY-SELECTED AGNs  

E-Print Network [OSTI]

From optical spectroscopy of X-ray sources observed as part of the Chandra Multi-wavelength Project (ChaMP), we present redshifts and classifications for a total of 1569 Chandra sources from our targeted spectroscopic ...

Trichas, Markos

163

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

SciTech Connect (OSTI)

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

164

X-ray absorption signatures of the molecular environment in water and ice  

E-Print Network [OSTI]

The x-ray absorption spectra of water and ice are calculated with a many-body approach for electron-hole excitations. The experimental features, including the small effects of temperature change in the liquid, are quantitatively reproduced from molecular configurations generated by ab-initio molecular dynamics. The spectral difference between the solid and the liquid is due to two major short range order effects. One, due to breaking of hydrogen bonds, enhances the pre-edge intensity in the liquid. The other, due to a non-bonded molecular fraction in the first coordination shell, affects the main spectral edge in the conversion of ice to water. This effect may not involve hydrogen bond breaking as shown by experiment in high-density amorphous ice.

Wei Chen; Xifan Wu; Roberto Car

2009-09-21T23:59:59.000Z

165

absorption spectroscopy xas: Topics by E-print Network  

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

absorption spectroscopy xas First Page Previous Page 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 Next Page Last Page Topic Index 1 Time Resolved X-Ray...

166

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

167

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

SciTech Connect (OSTI)

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

168

Particle Formation from Pulsed Laser Irradiation of SootAggregates studied with scanning mobility particle sizer, transmissionelectron microscope and near-edge x-ray absorption fine structure.  

SciTech Connect (OSTI)

We investigated the physical and chemical changes induced in soot aggregates exposed to laser radiation using a scanning mobility particle sizer, a transmission electron microscope, and a scanning transmission x-ray microscope to perform near-edge x-ray absorption fine structure spectroscopy. Laser-induced nanoparticle production was observed at fluences above 0.12 J/cm(2) at 532 nm and 0.22 J/cm(2) at 1064 nm. Our results indicate that new particle formation proceeds via (1) vaporization of small carbon clusters by thermal or photolytic mechanisms, followed by homogeneous nucleation, (2) heterogeneous nucleation of vaporized carbon clusters onto material ablated from primary particles, or (3) both processes.

Michelsen, Hope A.; Tivanski, Alexei V.; Gilles, Mary K.; vanPoppel, Laura H.; Dansson, Mark A.; Buseck, Peter R.; Buseck, Peter R.

2007-02-20T23:59:59.000Z

169

X-ray Spectroscopy of E2 and M3 Transitions in Ni-like W  

SciTech Connect (OSTI)

The electric quadrupole (E2) and magnetic octupole (M3) ground state transitions in Ni-like W{sup 46+} have been measured using high-resolution crystal spectroscopy at the Livermore electron beam ion trap facility. The lines fall in the soft x-ray region near 7.93 {angstrom} and were originally observed as an unresolved feature in tokamak plasmas. Using flat ADP and quartz crystals the wavelengths, intensities, and polarizations of the two lines have been measured for various electron beam energies and compared to intensity and polarization calculations performed using the Flexible Atomic Code (FAC).

Clementson, J; Beiersdorfer, P; Gu, M F

2009-11-09T23:59:59.000Z

170

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

SciTech Connect (OSTI)

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

171

High-pressure X-ray absorption fine structure in the diamond anvil cell and its applications in geological materials  

E-Print Network [OSTI]

nano- polycrystalline diamond instead of single crystal anvils, the influence of diamond diffractionHigh-pressure X-ray absorption fine structure in the diamond anvil cell and its applications fine structure in the diamond anvil cell and its applications in geological materials Xinguo Hong1

Duffy, Thomas S.

172

TENDER ENERGY X-RAY ABSORPTION SPECTROSCOPY (TES)  

E-Print Network [OSTI]

productivity at the earliest possible date. · Strategy combines in-house and external aspects to create world IMPACT: · Energy Materials: Photovoltaic, fuel-cell, battery and superconducting (nano

Ohta, Shigemi

173

X-ray Absorption Spectroscopy of Biologically Relevant Systems  

E-Print Network [OSTI]

of the interaction of the carboxylate with lithium; this isinteractions of carboxylate with the monovalent cations lithium,lithium acetate revealing distinct shifts between the cations, indicative of preferential interactions.

Uejio, Janel Sunayo

2010-01-01T23:59:59.000Z

174

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

175

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

SciTech Connect (OSTI)

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

176

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

SciTech Connect (OSTI)

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

177

A refined ephemeris and phase resolved X-ray spectroscopy of the Geminga pulsar  

E-Print Network [OSTI]

We present a refined phase-connected post-glitch ephemeris for the Geminga pulsar that is a good fit to all the post-glitch data from EGRET, ASCA, and XMM. We also present the results of phase-resolved spectroscopy of two XMM X-ray observations of the Geminga pulsar obtained in 2002 and 2004. An investigation is made into a previously claimed existence of a small hot spot on the neutron star surface. We conclude that that interpretation was more likely an artifact of an overly restrictive assumption used to fit the phase-resolved spectra, namely, that the spectral index of the non-thermal component is constant. When we allow the spectral index to vary as a function of rotation phase, we find systematic variations in spectral index, and such fits do not require an additional, hot blackbody component.

M. S. Jackson; J. P. Halpern

2005-09-02T23:59:59.000Z

178

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

179

First-Principles Calculation of Principal Hugoniot and K-Shell X-ray Absorption Spectra for Warm Dense KCl  

E-Print Network [OSTI]

Principal Hugoniot and K-shell X-ray absorption spectra of warm dense KCl are calculated using the first-principles molecular dynamics method. Evolution of electronic structures as well as the influence of the approximate description of ionization on pressure (caused by the underestimation of the energy gap between conduction bands and valence bands) in the first-principles method are illustrated by the calculation. Pressure ionization and thermal smearing are shown as the major factors to prevent the deviation of pressure from global accumulation along the Hugoniot. In addition, cancellation between electronic kinetic pressure and virial pressure further reduces the deviation. The calculation of X-ray absorption spectra shows that the band gap of KCl persists after the pressure ionization of the $3p$ electrons of Cl and K taking place at lower energy, which provides a detailed understanding to the evolution of electronic structures of warm dense matter.

Zhao, Shijun; Kang, Wei; Li, Zi; Zhang, Ping; He, Xian-Tu

2015-01-01T23:59:59.000Z

180

In situ x-ray absorption fine structure and optical reflectance studies of electrodeposited nickel hydrous oxide films in alkaline electrolytes.  

SciTech Connect (OSTI)

X-ray absorption fine structure (XAFS) and optical reflectance spectroscopy (RS) have been used to examine in situ electronic and structural aspects of nickel hydrous oxide, a-Ni(OH)2(hyd), electrodes supported on gold in alkaline electrolytes as a function of their state of charge. The extended X-ray absorption fine structure (EXAFS) of a-Ni(OH)2(hyd) electrodes in the uncharged (UC, or discharged) and overcharged (OC, or fully charged) states yielded, in each case, a single set of two distinct nearest-neighbor shells, with distances, d(Ni-O)1 = 2.05 {+-} 0.02 {angstrom} and d(Ni-Ni)1 = 3.11 {+-} 0.02 {angstrom} for UC, and d(Ni-O)1 = 1.87 {+-} 0.02 {angstrom} and d(Ni-Ni)1 = 2.83 {+-} 0.02 {angstrom} for OC. The in situ EXAFS of films allowed to self-discharge following overcharge could be fit with contributions from both sets of shells, suggesting that only two types of nickel sites are sufficient to account for the redox chemistry of this material. These data, in addition to information derived both from quantitative X-ray absorption near-edge structure (XANES) and optical RS in the visible range, indicate that the excess anodic charge, i.e., beyond the one-electron oxidation of Ni2+ sites, observed during the first oxidation of freshly prepared a-Ni(OH)2(hyd) electrodes may not be related to oxidation state changes involving nickel sites in the lattice, and, therefore, do not support the existence of nickel sites with a formal oxidation state higher than three for charged or overcharged electrodes in this media.

Hu, Y.; Bae, I. T.; Mo, Y.; Antonio, M. R.; Scherson, D. A.; Chemistry; Case Western Reserve Univ.

1997-01-01T23:59:59.000Z

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.


181

X-ray Emission Spectroscopy to Study Ligand Valence Orbitals in Mn Coordination Complexes  

SciTech Connect (OSTI)

We discuss a spectroscopic method to determine the character of chemical bonding and for the identification of metal ligands in coordination and bioinorganic chemistry. It is based on the analysis of satellite lines in X-ray emission spectra that arise from transitions between valence orbitals and the metal ion 1s level (valence-to-core XES). The spectra, in connection with calculations based on density functional theory (DFT), provide information that is complementary to other spectroscopic techniques, in particular X-ray absorption (XANES and EXAFS). The spectral shape is sensitive to protonation of ligands and allows ligands, which differ only slightly in atomic number (e.g., C, N, O...), to be distinguished. A theoretical discussion of the main spectral features is presented in terms of molecular orbitals for a series of Mn model systems: [Mn(H2O)6]2+, [Mn(H2O)5OH]+, [Mn(H2O)5NH2]+, and [Mn(H2O)5NH3]2+. An application of the method, with comparison between theory and experiment, is presented for the solvated Mn2+ ion in water and three Mn coordination complexes, namely [LMn(acac)N3]BPh4, [LMn(B2O3Ph2)(ClO4)], and [LMn(acac)N]BPh4, where L represents 1,4,7-trimethyl-1,4,7-triazacyclononane, acac stands for the 2,4-pentanedionate anion, and B2O3Ph2 represents the 1,3-diphenyl-1,3-dibora-2-oxapropane-1,3-diolato dianion.

Smolentsev, Grigory; Soldatov, Alexander V; Messinger, Johannes; Merz, Kathrin; Weyhermuller, Thomas; Bergmann, Uwe; Pushkar, Yulia; Yano, Junko; Yachandra, Vittal K.; Glatzel, Pieter

2009-03-02T23:59:59.000Z

182

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

SciTech Connect (OSTI)

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

183

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

SciTech Connect (OSTI)

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

184

Monitoring Long-Range Electron Transfer Pathways in Proteins by Stimulated Attosecond Broadband X-ray Raman Spectroscopy  

SciTech Connect (OSTI)

Long-range electron transfer (ET) plays a key role in many biological energy conversion and synthesis processes. We show that nonlinear spectroscopy with attosecond X-ray pulses provides a real time movie of the evolving oxidation states and electron densities around atoms, and can probe these processes with high spatial and temporal resolution. This is demonstrated in a simulation study of the stimulated X-ray Raman (SXRS) signals in Re-modified azurin, which had long served as a benchmark for long-range ET in proteins. Nonlinear SXRS signals are sensitive to the local electronic structure and should offer a novel window for long-range ET.

Zhang, Yu; Biggs, Jason; Govind, Niranjan; Mukamel, Shaul

2014-10-09T23:59:59.000Z

185

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

SciTech Connect (OSTI)

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

186

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

SciTech Connect (OSTI)

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

187

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.

188

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

189

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

190

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

SciTech Connect (OSTI)

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

191

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

SciTech Connect (OSTI)

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

192

Picosecond soft X-ray absorption measurement of the photo-inducedinsulator-to-metal transition in VO2.  

SciTech Connect (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 L3edge 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.

Cavalleri, Andrea; Chong, Henry H.W.; Fourmaux, Sylvain; Glover,Thornton E.; Heimann, Phil A.; Kieffer, Jean Claude; Mun, B. Simon; Padmore, Howard A.; Schoenlein, Robert W.

2004-02-01T23:59:59.000Z

193

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

SciTech Connect (OSTI)

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

194

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

SciTech Connect (OSTI)

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

195

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

SciTech Connect (OSTI)

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

196

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

197

Imaging X-ray spectroscopy with micro-X and Chandra  

E-Print Network [OSTI]

High spectral resolution observations of X-ray phenomena have the potential to uncover new physics. Currently, only point sources can be probed with high resolution spectra, using gratings. Extended objects like supernova ...

Rutherford, John (John Morton)

2013-01-01T23:59:59.000Z

198

X-ray afterglows and spectroscopy of Gamma-Ray Bursts  

E-Print Network [OSTI]

I will review the constraints set by X-ray measurements of afterglows on several issues of GRB, with particular regard to the fireball model, the environment, the progenitor and dark GRB.

Luigi Piro

2004-02-26T23:59:59.000Z

199

X-ray absorption fine structure and magnetization characterization of the  

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

AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr MayAtmosphericNuclear SecurityTensile Strain Switched FerromagnetismWaste and MaterialsWenjun1of EnergyX-rayNew Materials formetallic

200

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

SciTech Connect (OSTI)

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

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.


201

Sub-nanosecond time-resolved ambient-pressure X-ray photoelectron spectroscopy setup for pulsed and constant wave X-ray light sources  

SciTech Connect (OSTI)

An apparatus for sub-nanosecond time-resolved ambient-pressure X-ray photoelectron spectroscopy studies with pulsed and constant wave X-ray light sources is presented. A differentially pumped hemispherical electron analyzer is equipped with a delay-line detector that simultaneously records the position and arrival time of every single electron at the exit aperture of the hemisphere with ?0.1 mm spatial resolution and ?150 ps temporal accuracy. The kinetic energies of the photoelectrons are encoded in the hit positions along the dispersive axis of the two-dimensional detector. Pump-probe time-delays are provided by the electron arrival times relative to the pump pulse timing. An average time-resolution of (780 ± 20) ps (FWHM) is demonstrated for a hemisphere pass energy E{sub p} = 150 eV and an electron kinetic energy range KE = 503–508 eV. The time-resolution of the setup is limited by the electron time-of-flight (TOF) spread related to the electron trajectory distribution within the analyzer hemisphere and within the electrostatic lens system that images the interaction volume onto the hemisphere entrance slit. The TOF spread for electrons with KE = 430 eV varies between ?9 ns at a pass energy of 50 eV and ?1 ns at pass energies between 200 eV and 400 eV. The correlation between the retarding ratio and the TOF spread is evaluated by means of both analytical descriptions of the electron trajectories within the analyzer hemisphere and computer simulations of the entire trajectories including the electrostatic lens system. In agreement with previous studies, we find that the by far dominant contribution to the TOF spread is acquired within the hemisphere. However, both experiment and computer simulations show that the lens system indirectly affects the time resolution of the setup to a significant extent by inducing a strong dependence of the angular spread of electron trajectories entering the hemisphere on the retarding ratio. The scaling of the angular spread with the retarding ratio can be well approximated by applying Liouville's theorem of constant emittance to the electron trajectories inside the lens system. The performance of the setup is demonstrated by characterizing the laser fluence-dependent transient surface photovoltage response of a laser-excited Si(100) sample.

Shavorskiy, Andrey; Slaughter, Daniel S.; Zegkinoglou, Ioannis; Rude, Bruce S.; Bluhm, Hendrik [Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Neppl, Stefan; Cryan, James P.; Siefermann, Katrin R.; Weise, Fabian; Lin, Ming-Fu; Bacellar, Camila; Ziemkiewicz, Michael P.; Fraund, Matthew W.; Khurmi, Champak; Wright, Travis W.; Schoenlein, Robert W.; Gessner, Oliver, E-mail: ogessner@lbl.gov [Ultrafast X-ray Science Laboratory, Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Hertlein, Marcus P.; Tyliszczak, Tolek [Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Huse, Nils [Ultrafast X-ray Science Laboratory, Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Physics Department, University of Hamburg and Max-Planck Institute for Structure and Dynamics of Matter, 22761 Hamburg (Germany); and others

2014-09-15T23:59:59.000Z

202

X-Ray Spectroscopy of the Classical Nova V458 Vulpeculae with Suzaku  

E-Print Network [OSTI]

We conducted a target of opportunity X-ray observation of the classical nova V458 Vulpeculae 88 days after the explosion using the Suzaku satellite. With a 20 ks exposure, the X-ray Imaging Spectrometer detected X-ray emission significantly harder than typical super-soft source emission. The X-ray spectrum shows K lines from N, Ne, Mg, Si, and S, and L-series emission from Fe in highly ionized states. The spectrum can be described by a single temperature (0.64 keV) thin thermal plasma model in collisional equilibrium with a hydrogen-equivalent extinction column density of ~3e21/cm2, a flux of ~1e-12 erg/s/cm2, and a luminosity of ~6e34 erg/s in the 0.3-3.0 keV band at an assumed distance of 13 kpc. We found a hint of an enhancement of N and deficiencies of O and Fe relative to other metals. The observed X-ray properties can be interpreted as the emission arising from shocks of ejecta from an ONe-type nova.

Masahiro Tsujimoto; Dai Takei; Jeremy J. Drake; Jan-Uwe Ness; Shunji Kitamoto

2008-10-17T23:59:59.000Z

203

X-Ray Spectroscopy of the Classical Nova V458 Vulpeculae with Suzaku  

E-Print Network [OSTI]

We conducted a target of opportunity X-ray observation of the classical nova V458 Vulpeculae 88 days after the explosion using the Suzaku satellite. With a 20 ks exposure, the X-ray Imaging Spectrometer detected X-ray emission significantly harder than typical super-soft source emission. The X-ray spectrum shows K lines from N, Ne, Mg, Si, and S, and L-series emission from Fe in highly ionized states. The spectrum can be described by a single temperature (0.64 keV) thin thermal plasma model in collisional equilibrium with a hydrogen-equivalent extinction column density of ~3e21/cm2, a flux of ~1e-12 erg/s/cm2, and a luminosity of ~6e34 erg/s in the 0.3-3.0 keV band at an assumed distance of 13 kpc. We found a hint of an enhancement of N and deficiencies of O and Fe relative to other metals. The observed X-ray properties can be interpreted as the emission arising from shocks of ejecta from an ONe-type nova.

Tsujimoto, Masahiro; Drake, Jeremy J; Ness, Jan-Uwe; Kitamoto, Shunji

2008-01-01T23:59:59.000Z

204

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 (OSTI)

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

205

Multidimensional x-ray spectroscopy of valence and core excitations in Jason D. Biggs, Yu Zhang, Daniel Healion, and Shaul Mukamel  

E-Print Network [OSTI]

Multidimensional x-ray spectroscopy of valence and core excitations in cysteine Jason D. Biggs, Yu and core excitations in cysteine Jason D. Biggs, Yu Zhang, Daniel Healion, and Shaul Mukamela) Department

Mukamel, Shaul

206

In situ Ru K-edge x-ray absorption fine structure studies of electroprecipitated ruthenium dioxide films with relevance to supercapacitor applications.  

SciTech Connect (OSTI)

Modifications in electronic and structural aspects of RuO{sub 2} films electroprecipitated onto Au electrodes induced by changes in the applied potential have been examined in situ in aqueous 0.50 M H{sub 2}SO{sub 4} by Ru K-edge X-ray absorption spectroscopy (XAS). The Fourier transform of the k{sup 3}-weighted extended X-ray absorption fine structure (EXAFS), k{sup 3}x(k), for the film polarized at +1.20V vs RHE is characterized by two shells attributed to Ru-O and Ru-Ru interactions with average distances of 1.94(1) and 3.12(2) {angstrom}, respectively, in agreement with results obtained ex situ for Ru{sup 4+} in hydrous RuO{sub 2} by other groups. In contrast, films in the reduced state, i.e., +0.40 V vs RHE, yielded only a single shell ascribed to a Ru-O interaction at 2.02(1) {angstrom} with no evidence for a distant Ru-Ru shell. The long Ru-O distance is in agreement with that reported earlier for the hydrous Ru{sup 3+} ion [Ru-(OH{sub 2}){sub 6}]{sup 3+} in the solid state. Moreover, the difference between the average Ru-O bond lengths for the reduced and oxidized films is consistent with the difference in the ionic radii of Ru{sup 3+} and Ru{sup 4+}. On this basis it has been suggested that films in the reduced state contain Ru{sup 3+} sites, consistent with the electrochemical results, in a phase with apparently less order beyond the Ru-O coordination sphere than for hydrous RuO{sub 2}.

Mo, Y.; Antonio, M. R.; Stefan, I. C.; Scherson, D. A.; Chemistry; Case Western Reserve Univ.

2000-10-26T23:59:59.000Z

207

Femtosecond soft x-ray spectroscopy of solvated transition metal complexes: Deciphering the interplay of electronic and structural dynamics  

SciTech Connect (OSTI)

We present the first implementation of femtosecond soft X-ray spectroscopy as an ultrafast direct probe of the excited-state valence orbitals in solution-phase molecules. This method is applied to photoinduced spin crossover of [Fe(tren(py)3)]2+, where the ultrafast spinstate conversion of the metal ion, initiated by metal-to-ligand charge-transfer excitation, is directly measured using the intrinsic spin-state selectivity of the soft X-ray L-edge transitions. Our results provide important experimental data concerning the mechanism of ultrafast spin-state conversion and subsequent electronic and structural dynamics, highlighting the potential of this technique to study ultrafast phenomena in the solution phase.

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

2011-03-09T23:59:59.000Z

208

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

209

Vibronic fine structure in high-resolution x-ray absorption spectra from ion-bombarded boron nitride nanotubes  

SciTech Connect (OSTI)

The authors have applied high-resolution near-edge x-ray absorption fine structure measurements around the nitrogen K-edge to study the effects of ion-bombardment on near-surface properties of boron nitride nanotubes. A notable difference has been observed between surface sensitive partial electron yield (PEY) and bulk sensitive total electron yield (TEY) fine-structure measurements. The authors assign the PEY fine structure to the coupling of excited molecular vibrational modes to electronic transitions in NO molecules trapped just below the surface. Oxidation resistance of the boron nitride nanotubes is significantly reduced by low energy ion bombardment, as broken B-N bonds are replaced by N-O bonds involving oxygen present in the surface region. In contrast to the PEY spectra, the bulk sensitive TEY measurements on as-grown samples do not exhibit any fine structure while the ion-bombarded samples show a clear vibronic signature of molecular nitrogen.

Petravic, Mladen; Peter, Robert; Varasanec, Marijana [Department of Physics and Center for Micro and Nano Sciences and Technologies, University of Rijeka, 51000 Rijeka (Croatia); Li Luhua; Chen Ying [Institute for Technology Research and Innovation, Deakin University, Geelong Waurn Ponds Campus, 3217 (Australia); Cowie, Bruce C. C. [Australian Synchrotron, Clayton VIC 3168 (Australia)

2013-05-15T23:59:59.000Z

210

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 (OSTI)

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

211

X-ray continuum emission spectroscopy from hot dense matter at Gbar pressures  

SciTech Connect (OSTI)

We have measured the time-resolved x-ray continuum emission spectrum of ?30 times compressed polystyrene created at stagnation of spherically convergent shock waves within the Gbar fundamental science campaign at the National Ignition Facility. From an exponential emission slope between 7.7 keV and 8.1 keV photon energy and using an emission model which accounts for reabsorption, we infer an average electron temperature of 375 ± 21 eV, which is in good agreement with HYDRA-1D simulations.

Kraus, D., E-mail: dominik.kraus@berkeley.edu; Falcone, R. W. [Department of Physics, University of California, Berkeley, California 94720 (United States); Döppner, T.; Kritcher, A. L.; Bachmann, B.; Collins, G. W.; Hawreliak, J. A.; Landen, O. L.; Ma, T.; Le Pape, S.; Swift, D. C. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Chapman, D. A. [Plasma Physics Group, Radiation Physics Department, AWE plc, Reading RG7 4PR, United Kingdom and Centre for Fusion, Space and Astrophysics, University of Warwick, Coventry CV4 7AL (United Kingdom); Glenzer, S. H. [SLAC National Accelerator Laboratory, Menlo Park, California 94309 (United States); Neumayer, P. [GSI Helmholtzzentrum für Schwerionenforschung, 64291 Darmstadt (Germany)

2014-11-15T23:59:59.000Z

212

Ambient Pressure Photoelectron Spectroscopy Using Soft X-ray and Hard  

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

AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr May JunDatastreamsmmcrcalgovInstrumentsruc DocumentationP-Series to someone by E-mail Share AlternativeRightAlvaroX-ray, and its

213

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

SciTech Connect (OSTI)

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

214

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

215

In situ X-ray absorption fine structure studies of foreign metal ions in nickel hydrous oxide electrodes in alkaline electrolytes  

SciTech Connect (OSTI)

Aspects of the structural and electronic properties of hydrous oxide films of composite (9:1) Ni/Co and (9:1) Ni/Fe, prepared by electrodeposition, have been examined in alkaline electrolytes using in situ X-ray absorption fine structure (XAFS). An analysis of the X-ray absorption near the edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) for the Co and Fe K-edges of these composite hydrous oxides revealed that, regardless of the oxidation state of nickel sites in the films, the guest metal ions are present as Co[sup 3+] and Fe[sup 3+] and that the cobalt-oxygen distance d(Co-O) = 1.9 [+-] 0.02 [angstrom] and d(Fe-O) = 1.92 [+-] 0.02 [angstrom]. The latter values are in excellent agreement with d(Me-O) (Me = Co or Fe) in CoOOH and [beta]- and [gamma]-FeOOH, respectively, determined by conventional X-ray diffraction. Two clearly defined Me-Ni first coordination shells could be observed in the Fourier transforms (FT) of the K-edge EXAFS of the guest metal recorded at a potential at which both Ni[sup 2+] and Ni[sup 3+] sites are expected to be present. 28 refs., 10 figs., 3 tabs.

Kim, Sunghyun; Tryk, D.A.; Scherson, D. (Case Western Reserve Univ., Cleveland, OH (United States)); Antonio, M.R. (Argonne National Lab., IL (United States)); Carr, R. (Stanford Synchrotron Radiation Lab., CA (United States))

1994-10-06T23:59:59.000Z

216

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

217

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 (OSTI)

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

218

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 (OSTI)

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

219

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

SciTech Connect (OSTI)

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

220

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

SciTech Connect (OSTI)

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

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

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

SciTech Connect (OSTI)

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

222

Non-matrix corrected organic sulfur determination by energy dispersive X-ray spectroscopy for western Kentucky coals and residues  

SciTech Connect (OSTI)

A method for non-matrix corrected organic sulfur analysis by energy dispersive X-ray spectroscopy has been developed using petroleum coke standards. Typically, electron beam microanalysis is a rapid, nondestructive analytical technique to quantitatively measure organic sulfur in coal. The results show good correlation to ASTM values for numerous well characterized coals with a wide range in total and pyritic sulfur content. This direct analysis is capable of reducing error commonly associated with the present ASTM method which relies on an indirect measure of organic sulfur by difference. The precision of the organic sulfur values determined in the present study is comparable to that obtained by ZAF matrix corrected microanalysis. The energy dispersive microanalysis is capable of measuring micro as well as bulk organic sulfur levels.

Clark, C.P.; Freeman, G.B.; Hower, J.C.

1984-01-01T23:59:59.000Z

223

Proceedings of the eighth international colloquium on ultraviolet and x-ray spectroscopy of astrophysical and laboratory plasmas (IAU colloquium 86)  

SciTech Connect (OSTI)

This volume represents the Proceedings of the Eighth International Colloquium on Ultraviolet and X-Ray Spectroscopy of Astrophysical and Laboratory Plasmas. The aim of this series of colloquia has been to bring together workers in the fields of astrophysical spectroscopy, laboratory spectroscopy and atomic physics in order to exchange ideas and results on problems which are common to these different disciplines. In addition to the presented papers there was a poster paper session. (WRF)

Not Available

1984-01-01T23:59:59.000Z

224

X-ray and EUV Spectroscopy of the Boundary Layer Emission of Nonmagnetic Cataclysmic Variables  

E-Print Network [OSTI]

EUVE, ROSAT, and ASCA observations of the boundary layer emission of nonmagnetic cataclysmic variables (CVs) are reviewed. EUVE spectra reveal that the effective temperature of the soft component of high-Mdot nonmagnetic CVs is kT ~ 10-20 eV and that its luminosity is ~ 0.1-0.5 times the accretion disk luminosity. Although the EUV spectra are very complex and belie simple interpretation, the physical conditions of the boundary layer gas are constrained by emission lines of highly ionized Ne, Mg, Si, and Fe. ROSAT and ASCA spectra of the hard component of nonmagnetic CVs are satisfactorily but only phenomenologically described by multi-temperature thermal plasmas, and the constraints imposed on the physical conditions of this gas are limited by the relatively weak and blended lines. It is argued that significant progress in our understanding of the X-ray spectra of nonmagnetic CVs will come with future observations with XMM, AXAF, and Astro-E.

Christopher W. Mauche

1997-09-11T23:59:59.000Z

225

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

SciTech Connect (OSTI)

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

226

Suzaku Spectroscopy Study of Hard X-Ray Emission in the Arches Cluster  

E-Print Network [OSTI]

We present the results of a Suzaku study of the Arches cluster. A high S/N spectrum in the 3-12 keV band was obtained with the XIS. We found that the spectrum consists of a thermal plasma, a hard power-law tail, and two Gaussian lines. The plasma component (kT~2.2 keV) is established from the presence of CaXIX and FeXXV K alpha lines as well as the absence of FeXXVI K alpha line. The two Gaussian lines represent the K alpha and beta lines from iron at lower ionization stages. Both the line centers and the intensity ratio of these two lines are consistent with the neutral iron. The hard power-law tail (index~0.7) was found to have no pronounced iron K edge feature. In comparison with the published Chandra spectra, we conclude that the thermal component is from the ensemble of point-like sources plus thermal diffuse emission concentrated at the cluster center, while the Gaussian and the hard tail components are from the non-thermal diffuse emission extended in a larger scale. In the band-limited XIS images, the distribution of the 7.5-10.0 keV emission resembles that of the 6.4 keV emission. This strongly suggests that the power-law emission is related to the 6.4 and 7.1 keV lines in the underlying physics. We discuss two ideas to explain both the hard continuum and the lines: (1) X-ray photoionization that produces fluorescence lines and the Thomson scattering continuum and (2) non-thermal electron impact ionization of iron atoms and bremsstrahlung continuum. But whichever scenario is adopted, the photon or particle flux from the Arches cluster is too low to account for the observed line and continuum intensity.

M. Tsujimoto; Y. Hyodo; K. Koyama

2006-11-03T23:59:59.000Z

227

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...

228

X-ray diffraction and extended X-ray absorption fine structure study of epitaxial mixed ternary bixbyite Pr{sub x}Y{sub 2-x}O{sub 3} (x = 0-2) films on Si (111)  

SciTech Connect (OSTI)

Ternary single crystalline bixbyite Pr{sub x}Y{sub 2-x}O{sub 3} films over the full stoichiometry range (x = 0-2) have been epitaxially grown on Si (111) with tailored electronic and crystallographic structure. In this work, we present a detailed study of their local atomic environment by extended X-ray absorption fine structure at both Y K and Pr L{sub III} edges, in combination with complementary high resolution x-ray diffraction measurements. The local structure exhibits systematic variations as a function of the film composition. The cation coordination in the second and third coordination shells changes with composition and is equal to the average concentration, implying that the Pr{sub x}Y{sub 2-x}O{sub 3} films are indeed fully mixed and have a local bixbyite structure with random atomic-scale ordering. A clear deviation from the virtual crystal approximation for the cation-oxygen bond lengths is detected. This demonstrates that the observed Vegard's law for the lattice variation as a function of composition is based microscopically on a more complex scheme related to local structural distortions which accommodate the different cation-oxygen bond lengths.

Niu, G.; Zoellner, M. H.; Zaumseil, P. [IHP, Im Technologiepark 25, 15236 Frankfurt (Oder) (Germany); Pouliopoulos, A. [Department of Physics and Astronomy, University of Bologna, viale C. BertiPichat 6/2, 40127 Bologna (Italy); D'Acapito, F. [Consiglio Nazionale delle Ricerche, Istituto Officina dei Materiali, Operative Group in Grenoble, c/o European Synchrotron Radiation Facility, B.P. 220, 38043 Grenoble (France); Schroeder, T. [IHP, Im Technologiepark 25, 15236 Frankfurt (Oder) (Germany); BTU Cottbus, Konrad-Zuse-Str. 1, 03046 Cottbus (Germany); Boscherini, F. [Department of Physics and Astronomy, University of Bologna, viale C. BertiPichat 6/2, 40127 Bologna (Italy); Consiglio Nazionale delle Ricerche, Istituto Officina dei Materiali, Operative Group in Grenoble, c/o European Synchrotron Radiation Facility, B.P. 220, 38043 Grenoble (France)

2013-01-28T23:59:59.000Z

229

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

SciTech Connect (OSTI)

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

230

ANALYSIS OF PASSIVATED SURFACES FOR MASS SPECTROMETER INLET SYSTEMS BY AUGER ELECTRON AND X-RAY PHOTOELECTRON SPECTROSCOPY  

SciTech Connect (OSTI)

Stainless steel coupons approximately 0.5' in diameter and 0.125' thick were passivated with five different surface treatments and an untreated coupon was left as a control. These surface treatments are being explored for use in tritium storage containers. These coupons were made to allow surface analysis of the surface treatments using well-know surface analysis techniques. Depth profiles using Auger electron spectroscopy (AES) and X-ray photoelectron spectroscopy (XPS) were performed on these coupons to characterize the surface and near surface regions. Scanning electron microscope (SEM) images were collected as well. All of the surface treatments studied here appear to change the surface morphology dramatically, as evidenced by lack of tool marks on the treated samples. In terms of the passivation treatment, Vendors A-D appeared to have oxide layers that were very similar in thickness to each other (0.7-0.9 nm thick) as well as the untreated samples (the untreated sample oxide layers appeared to be somewhat larger). Vendor E's silicon coating appears to be on the order of 200 nm thick.

Ajo, H.; Clark, E.

2010-09-01T23:59:59.000Z

231

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 (OSTI)

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

232

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

SciTech Connect (OSTI)

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

233

Elemental content of enamel and dentin after bleaching of teeth (a comparative study between laser-induced breakdown spectroscopy and x-ray photoelectron spectroscopy)  

SciTech Connect (OSTI)

The elemental content of the superficial and inner enamel as well as that of dentin was analyzed using laser-induced breakdown spectroscopy (LIBS) and x-ray photoelectron spectroscopy (XPS) of bleached and unbleached tooth specimens. It is thus clear from the spectral analysis using both the LIBS and XPS technique that elemental changes (though insignificant within the scopes of this study) of variable intensities do occur on the surface of the enamel and extend deeper to reach dentin. The results of the LIBS revealed a slight reduction in the calcium levels in the bleached compared to the control specimens in all the different bleaching groups and in both enamel and dentin. The good correlation found between the LIBS and XPS results demonstrates the possibility of LIBS technique for detection of minor loss in calcium and phosphorus in enamel and dentin.

Imam, H. [National Institute of Laser Enhanced Sciences, NILES, Cairo University, Giza (Egypt)] [National Institute of Laser Enhanced Sciences, NILES, Cairo University, Giza (Egypt); Ahmed, Doaa [Department of Restorative Sciences, Faculty of Dentistry, Alexandria University, Alexandria (Egypt)] [Department of Restorative Sciences, Faculty of Dentistry, Alexandria University, Alexandria (Egypt); Eldakrouri, Ashraf [National Institute of Laser Enhanced Sciences, NILES, Cairo University, Giza (Egypt) [National Institute of Laser Enhanced Sciences, NILES, Cairo University, Giza (Egypt); Department of Optometry and Vision Science, College of Applied Medical Science, King Saud University, Riyadh (Saudi Arabia)

2013-06-21T23:59:59.000Z

234

Percolative superconductivity in La{sub 2}CuO{sub 4.06} by lattice granularity patterns with scanning micro x-ray absorption near edge structure  

SciTech Connect (OSTI)

The simplest cuprate superconductor La{sub 2}CuO{sub 4+y} with mobile oxygen interstitials exhibits a clear phase separation. It is known that oxygen interstitials enter into the rocksalt La{sub 2}O{sub 2+y} spacer layers forming oxygen interstitials rich puddles and poor puddles but only recently a bulk multiscale structural phase separation has been observed by using scanning micro X-ray diffraction. Here we get further information on their spatial distribution, using scanning La L{sub 3}-edge micro X-ray absorption near edge structure. Percolating networks of oxygen rich puddles are observed in different micrometer size portions of the crystals. Moreover, the complex surface resistivity shows two jumps associated to the onset of intra-puddle and inter-puddles percolative superconductivity. The similarity of oxygen doped La{sub 2}CuO{sub 4+y}, with the well established phase separation in iron selenide superconductors is also discussed.

Poccia, Nicola [MESA Institute for Nanotechnology, University of Twente, P. O. Box 217, 7500AE Enschede (Netherlands); RICMASS Rome International Center for Materials Science Superstripes, via dei Sabelli 119A, 00185 Roma (Italy); Chorro, Matthieu [Synchrotron SOLEIL L'Orme des Merisiers, 91190 Paris S.Aubin (France); Ricci, Alessandro [Deutsches Elektronen-Synchrotron DESY, Notkestraße 85, D-22607 Hamburg (Germany); RICMASS Rome International Center for Materials Science Superstripes, via dei Sabelli 119A, 00185 Roma (Italy); Xu, Wei [Beijing Synchrotron Radiation Facility, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049 (China); Marcelli, Augusto [Istituto Nazionale di Fisica Nucleare - Laboratori Nazionali di Frascati, 00044 Frascati, Rome (Italy); NSRL, University of Science and Technology of China, Hefei 230026 (China); RICMASS Rome International Center for Materials Science Superstripes, via dei Sabelli 119A, 00185 Roma (Italy); Campi, Gaetano [Institute of Crystallography, CNR, via Salaria Km 29.300, Monterotondo, 00015 Rome (Italy); RICMASS Rome International Center for Materials Science Superstripes, via dei Sabelli 119A, 00185 Roma (Italy); Bianconi, Antonio [RICMASS Rome International Center for Materials Science Superstripes, via dei Sabelli 119A, 00185 Roma (Italy); Institute of Crystallography, CNR, via Salaria Km 29.300, Monterotondo, 00015 Rome (Italy)

2014-06-02T23:59:59.000Z

235

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

SciTech Connect (OSTI)

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

236

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

SciTech Connect (OSTI)

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

237

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

SciTech Connect (OSTI)

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

238

Analysis of the surface of tricalcium silicate during the induction period by X-ray photoelectron spectroscopy  

SciTech Connect (OSTI)

X-ray photoelectron spectroscopy allows the analysis of surface layers with a thickness of a few nanometers. The method is sensitive to the chemical environment of the atoms since the binding energy of the electrons depends on the chemical bonds to neighboring atoms. It has been applied to the hydration of tricalcium silicate (Ca{sub 3}SiO{sub 5}, C{sub 3}S) by analyzing a sample after 30 min of hydration. Also two references have been investigated namely anhydrous C{sub 3}S and intermediate phase in order to enable a quantitative evaluation of the experimental data. In the hydrated C{sub 3}S sample, the analyzed volume (0.2 mm{sup 2} surface by 13 nm depth) contained approximately 44 wt.% of C{sub 3}S and 56 wt.% of intermediate phase whereas C-S-H was not detected. Scanning Electron Microscopy data and geometric considerations indicate that the intermediate phase forms a thin layer having a thickness of approximately 2 nm and covers the complete surface instead of forming isolated clusters.

Bellmann, F., E-mail: frank.bellmann@uni-weimar.de [Institute for Building Materials Science, Bauhaus University Weimar, 99423 Weimar (Germany); Sowoidnich, T.; Ludwig, H.-M. [Institute for Building Materials Science, Bauhaus University Weimar, 99423 Weimar (Germany)] [Institute for Building Materials Science, Bauhaus University Weimar, 99423 Weimar (Germany); Damidot, D. [Ecole des Mines de Douai, Civil and Environmental Engineering Department, 941 rue Charles Bourseul, BP 10838, 59508 Doua cedex (France)] [Ecole des Mines de Douai, Civil and Environmental Engineering Department, 941 rue Charles Bourseul, BP 10838, 59508 Doua cedex (France)

2012-09-15T23:59:59.000Z

239

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

240

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.

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

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

SciTech Connect (OSTI)

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

242

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

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

243

Absorption spectroscopy of a laboratory photoionized plasma experiment at Z  

SciTech Connect (OSTI)

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

244

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

245

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

246

Investigating Silicon-Based Photoresists with Coherent Anti-Stokes Raman Scattering and X-ray Micro-spectroscopy  

E-Print Network [OSTI]

LIGHT (X- RAYS , EUV, ULTRAFAST PULSES ), OR HEAT . T HEthe “on” time of an ultrafast pulse is referred to as thepeak-power of the ultrafast pulses, purely electronic four-

Caster, Allison G.

2010-01-01T23:59:59.000Z

247

The determination of interfacial structure and phase transitions in Al/Cu and Al/Ni interfaces by means of surface extended x-ray absorption fine structure  

SciTech Connect (OSTI)

Surface extended x-ray absorption fine structure (SEXAFS) was used to investigate the interfacial conditions of Al/Cu and Al/Ni shallow buried interfaces. Previous studies using glancing angle extended x-ray absorption fine structure, x-ray reflectivity, photoemission, and SEXAFS produced conflicting results as to whether or not the interfaces between Al and Cu and Al and Ni were reacted upon room temperature deposition. In this study polycrystalline bilayers of Al/Cu and Al/Ni and trilayers of Al/Cu/Al and Al/Ni/Al were deposited on tantalum foil at room temperature in ultra high vacuum and analyzed to evaluate the reactivity of these systems on a nanometer scale. It become overwhelming apparent that the interfacial phase reactions were a function of the vacuum conditions. Samples deposited with the optimum vacuum conditions showed reaction products upon deposition at room temperature which were characterized by comparisons to standards and by least squares fitting the be CuAl{sub 2} and NiAl{sub 3} respectively. The results of this study that the reacted zone thicknesses were readily dependent on the deposition parameters. For both Al on Cu and Al on Ni as well as the metal on Al conditions 10{Angstrom} reaction zones were observed. These reaction zones were smaller than that observed for bilayers of Al on Cu (30{Angstrom}) and Al on Ni (60{Angstrom}) where deposition rates were much higher and samples were much thicker. The reaction species are evident by SEXAFS, where the previous photoemission studies only indicated that changes had occurred. Improved vacuum conditions as compared to the earlier experiments is primarily the reason reactions on deposition were seen in this study as compared to the earlier SEXAFS studies.

Barrera, E.V. (Rice Univ., Houston, TX (United States). Dept. of Mechanical Engineering and Materials Science); Heald, S.M. (Brookhaven National Lab., Upton, NY (United States))

1991-01-01T23:59:59.000Z

248

The determination of interfacial structure and phase transitions in Al/Cu and Al/Ni interfaces by means of surface extended x-ray absorption fine structure  

SciTech Connect (OSTI)

Surface extended x-ray absorption fine structure (SEXAFS) was used to investigate the interfacial conditions of Al/Cu and Al/Ni shallow buried interfaces. Previous studies using glancing angle extended x-ray absorption fine structure, x-ray reflectivity, photoemission, and SEXAFS produced conflicting results as to whether or not the interfaces between Al and Cu and Al and Ni were reacted upon room temperature deposition. In this study polycrystalline bilayers of Al/Cu and Al/Ni and trilayers of Al/Cu/Al and Al/Ni/Al were deposited on tantalum foil at room temperature in ultra high vacuum and analyzed to evaluate the reactivity of these systems on a nanometer scale. It become overwhelming apparent that the interfacial phase reactions were a function of the vacuum conditions. Samples deposited with the optimum vacuum conditions showed reaction products upon deposition at room temperature which were characterized by comparisons to standards and by least squares fitting the be CuAl{sub 2} and NiAl{sub 3} respectively. The results of this study that the reacted zone thicknesses were readily dependent on the deposition parameters. For both Al on Cu and Al on Ni as well as the metal on Al conditions 10{Angstrom} reaction zones were observed. These reaction zones were smaller than that observed for bilayers of Al on Cu (30{Angstrom}) and Al on Ni (60{Angstrom}) where deposition rates were much higher and samples were much thicker. The reaction species are evident by SEXAFS, where the previous photoemission studies only indicated that changes had occurred. Improved vacuum conditions as compared to the earlier experiments is primarily the reason reactions on deposition were seen in this study as compared to the earlier SEXAFS studies.

Barrera, E.V. [Rice Univ., Houston, TX (United States). Dept. of Mechanical Engineering and Materials Science; Heald, S.M. [Brookhaven National Lab., Upton, NY (United States)

1991-12-31T23:59:59.000Z

249

A Fast, Versatile Nanoprobe for Complex Materials: The Sub-micron Resolution X-ray Spectroscopy Beamline at NSLS-II (491st Brookhaven Lecture)  

SciTech Connect (OSTI)

Time is money and for scientists who need to collect data at research facilities like Brookhaven Lab’s National Synchrotron Light Source (NSLS), “beamtime” can be a precious commodity. While scanning a complex material with a specific technique and standard equipment today would take days to complete, researchers preparing to use brighter x-rays and the new sub-micron-resolution x-ray spectroscopy (SRX) beamline at the National Synchrotron Light Source II (NSLS-II) could scan the same sample in greater detail with just a few hours of beamtime. Talk about savings and new opportunities for researchers! Users will rely on these tools for locating trace elements in contaminated soils, developing processes for nanoparticles to deliver medical treatments, and much more. Dr. Thieme explains benefits for next-generation research with spectroscopy and more intense x-rays at NSLS-II. He discusses the instrumentation, features, and uses for the new SRX beamline, highlighting its speed, adjustability, and versatility for probing samples ranging in size from millimeters down to the nanoscale. He will talk about complementary beamlines being developed for additional capabilities at NSLS-II as well.

Thieme, Juergen [BNL Photon Sciences Directorate

2014-02-06T23:59:59.000Z

250

Spectroscopy of M-shell x-ray transitions in Zn-like through Co-like W  

SciTech Connect (OSTI)

The M-shell x-ray emission of highly charged tungsten ions has been investigated at the Livermore electron beam ion trap facility. Using the SuperEBIT electron beam ion trap and a NASA x-ray calorimeter array, transitions connecting the ground configurations in the 1500-3600 eV spectral range of zinc-like W{sup 44+} through cobalt-like W{sup 47+} have been measured. The measured spectra are compared with theoretical line positions and emissivities calculated using the FAC code.

Clementson, J; Beiersdorfer, P; Brown, G V; Gu, M F

2009-07-08T23:59:59.000Z

251

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

SciTech Connect (OSTI)

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

252

X-ray diffraction and EXAFS analysis of materials for lithium-based rechargeable batteries  

SciTech Connect (OSTI)

Lithium iron phosphate LiFePO{sub 4} (triphylite) and lithium titanate Li{sub 4}Ti{sub 5}O{sub 12} are used as components of a number of active materials in modern rechargeable batteries. Samples of these materials are studied by X-ray diffraction and extended X-ray absorption fine structure (EXAFS) spectroscopy. Hypotheses about the phase composition of the analyzed samples are formulated.

Sharkov, M. D., E-mail: mischar@mail.ioffe.ru; Boiko, M. E.; Bobyl, A. V.; Ershenko, E. M.; Terukov, E. I. [Russian Academy of Sciences, Ioffe Physical-Technical Institute (Russian Federation); Zubavichus, Y. V. [National Research Centre “Kurchatov Institute” (Russian Federation)

2013-12-15T23:59:59.000Z

253

NuSTAR STUDY OF HARD X-RAY MORPHOLOGY AND SPECTROSCOPY OF PWN G21.5–0.9  

E-Print Network [OSTI]

We present NuSTAR high-energy X-ray observations of the pulsar wind nebula (PWN)/supernova remnant G21.5–0.9. We detect integrated emission from the nebula up to ~40 keV, and resolve individual spatial features over a broad ...

Nynka, Melania

254

Journal of Electron Spectroscopy and Related Phenomena 144147 (2005) 259269 Soft X-ray spectromicroscopy of biological  

E-Print Network [OSTI]

in the case of electron beam based techniques; radiation damage in the case of electron microscopy; lack. This requires a source of bright, continu- ouslytunablesoftX-rays(50­2000 eV),andthussynchrotron radiation spatial reso- lution in the case of IR, NMR and optical techniques; inabil- ity to couple to wet specimens

Hitchcock, Adam P.

255

High-Dispersion Spectroscopy of the X-Ray Transient RXTE J0421+560 (= CI Cam) during Outburst  

E-Print Network [OSTI]

We obtained high dispersion spectra of CI Cam, the optical counterpart of XTE J0421+560, two weeks after the peak of its short outburst in 1998 April. The optical counterpart is a supergiant B[e] star emitting a two-component wind. The cool wind (the source of narrow emission lines of neutral and ionized metals) has a velocity of 32 km/s and a temperature near 8000 K. Dense and roughly spherical, it fills the space around the sgB[e] star, and, based on the size of an infrared-emitting dust shell around the system, extends to a radius between 13 - 50 AU. It carries away mass at a high rate, Mdot > 10^(-6) solar masses per year. The hot wind has a velocity in excess of 2500 km/s and a temperature of 1.7 +/-0.3 x 10^4 K. From UV spectra of CI Cam obtained in 2000 March with Hubble Space Telescope, we derive a differential extinction E(B-V) = 0.85 +/- 0.05. We derive a distance to CI Cam > 5 kpc. Based on this revised distance, the X-ray luminosity at the peak of the outburst was L(2-25 keV) > 3.0 x 10^38 erg/s, making CI Cam one of the most luminous X-ray transients. The ratio of quiescent to peak luminosity in the 2 - 25 keV band is < 1.7 x 10^(-6). The compact star in CI Cam is immersed in the dense circumstellar wind from the sgB[e] star and burrows through the wind producing little X-ray emission except for rare transient outbursts. This picture (a compact star traveling in a wide orbit through the dense circumstellar envelope of a sgB[e] star, occasionally producing transient X-ray outbursts) makes CI Cam unique among the known X-ray binaries. Strong circumstantial evidence suggests that the compact object is a black hole, not a neutron star. We speculate that the X-ray outburst was short because the accretion disk around the compact star is fed from a stellar wind and is smaller than disks fed by Roche-lobe overflow.

Edward L. Robinson; Inese I. Ivans; William F. Welsh

2001-10-04T23:59:59.000Z

256

AugEX: AUGER ELECTRON AND X-RAY SPECTROMETER ON CHANDRAYAAN-2 ROVER  

E-Print Network [OSTI]

for determining elemental composition which have a space heritage X-Ray Fluorescence (XRF) Particle-induced X-ray fluorescence (XRF) Expected Advantage: cover low Z elements with higher sensitivity than XRF or PIXE. ACHARYA-ray absorption or charged particle bombardment X-ray emission induced by X-ray absorption: XRF X-ray emission

Bapat, Bhas

257

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

SciTech Connect (OSTI)

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

258

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

SciTech Connect (OSTI)

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

259

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

260

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

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

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

E-Print Network [OSTI]

SPINACH CHLOROPLASTS Jon Allan Kirby (Ph.D. thesis) May 1981SPINACH CHLOROPLASTS Jon Allan Kirby Ph.D. Thesis May 1981Spinach Chloroplasts Jon Allan Kirby B.S. (Ottawa

Kirby, Jon Allan

2012-01-01T23:59:59.000Z

262

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 290 eV clearly indicate a preferential interaction of sodium versus potassium, which was less apparent interactions aqueous systems The discovery of the selective interactions between simple ions and proteins dates

Cohen, Ronald C.

263

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

264

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

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

AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr May JunDatastreamsmmcrcalgovInstrumentsrucLasDelivered‰PNGExperience hands-onASTROPHYSICSHe β-Research and EducationF O S R / 1 9 4

265

Speciation of arsenic in pyrite by micro-X-ray absorption fine- structure spectroscopy (XAFS)  

SciTech Connect (OSTI)

Pyrite (FeS2) often contains variable levels of arsenic, regardless of the environment of formation. Arsenian pyrite has been reported in coals, sediments and ore deposits. Arsenian pyrite having As concentrations of up to 10 wt % in sedimentary rocks (Kolker et al. 1997), about 10 wt% in gold deposits (Fleet et al. 1993), 12 wt % in a refractory gold ore (Paktunc et al. 2006) and 20 wt % in a Carlin-type gold deposit in Nevada (Reich et al. 2005) have been reported. Arsenian pyrite is the carrier of gold in hydrothermal Carlin-type gold deposits, and gold concentrations of up to 0.9 wt % have been reported (Reich et al. 2005; Paktunc et al. 2006). In general, high Au concentrations correlate with As-rich zones in pyrite (Paktunc et al. 2006). Pyrite often ends up in mining and metallurgical wastes as an unwanted mineral and consititutes one of the primary sources of As in the wastes. Arsenic can be readily released to the environment due to rapid oxidative dissolution of host pyrite under atmospheric conditions. Pyrite is also the primary source of arsenic in emissions and dust resulting from combustion of bituminous coals. Despite the importance of arsenian pyrite as a primary source of anthropogenic arsenic in the environment and its economic significance as the primary carrier of gold in Carlin-type gold deposits, our understanding of the nature of arsenic in pyrite is limited. There are few papers dealing with the mode of occurrence of arsenic by bulk XAFS in a limited number of pyrite-bearing samples. The present study documents the analysis of pyrite particles displaying different morphologies and a range of arsenic and gold concentrations to determine the nature and speciation of arsenic.

Paktunc, D. (CCM)

2008-09-30T23:59:59.000Z

266

Iodine valence and local environments in borosilicate waste glasses using X-ray absorption spectroscopy  

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

AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr May JunDatastreamsmmcrcalgovInstrumentsruc DocumentationP-SeriesFlickrinformation for and ApplicationNuclearLeaoInvestingsolubility in

267

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

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

AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr May Jun Jul(Summary)morphinanInformation Desert Southwest Region service area. TheEPSCIResearch to sponsor Brazilianmaterials |

268

Simulating Ru L3-edge X-ray Absorption Spectroscopy with Time-Dependent  

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

AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr MayAtmosphericNuclear Security Administrationcontroller systemsBi (2)Sharing Smart GridShiftMethod forA "Sponge" Path

269

Using Light to Control How X Rays Interact with Matter  

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

pulse, a heretofore difficult challenge. This capability should help to further develop ultrafast x-ray spectroscopy. ALS femtosecond spectroscopy beamline layout. Femtosecond...

270

X-ray/UV Observing Campaign on the Mrk 279 AGN Outflow: A Global Fitting Analysis of the UV Absorption  

E-Print Network [OSTI]

We present an analysis of the intrinsic UV absorption in the Seyfert 1 galaxy Mrk 279 based on simultaneous long observations with the Hubble Space Telescope (41 ks) and the Far Ultraviolet Spectroscopic Explorer (91 ks). To extract the line-of-sight covering factors and ionic column densities, we separately fit two groups of absorption lines: the Lyman series and the CNO lithium-like doublets. For the CNO doublets we assume that all three ions share the same covering factors. The fitting method applied here overcomes some limitations of the traditional method using individual doublet pairs; it allows for the treatment of more complex, physically realistic scenarios for the absorption-emission geometry and eliminates systematic errors that we show are introduced by spectral noise. We derive velocity-dependent solutions based on two models of geometrical covering -- a single covering factor for all background emission sources, and separate covering factors for the continuum and emission lines. Although both models give good statistical fits to the observed absorption, we favor the model with two covering factors because: (a) the best-fit covering factors for both emission sources are similar for the independent Lyman series and CNO doublet fits; (b) the fits are consistent with full coverage of the continuum source and partial coverage of the emission lines by the absorbers, as expected from the relative sizes of the nuclear emission components; and (c) it provides a natural explanation for variability in the Ly$\\alpha$ absorption detected in an earlier epoch. We also explore physical and geometrical constraints on the outflow from these results.

Jack R. Gabel; Nahum Arav; Jelle S. Kaastra; Gerard A. Kriss; Ehud Behar; Elisa Costantini; C. Martin Gaskell; Kirk T. Korista; Ari Laor; Frits Paerels; Daniel Proga; Jessica Kim Quijano; Masao Sako; Jennifer E. Scott; Katrien C. Steenbrugge

2005-01-25T23:59:59.000Z

271

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

SciTech Connect (OSTI)

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

272

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

273

A Method of Mass Measurement in Black Hole Binaries Using Timing and High Resolution X-ray Spectroscopy  

E-Print Network [OSTI]

In X-ray binaries, several percent of the compact object luminosity is intercepted by the surface of the normal companion and re-radiated through Compton reflection and the K-fluorescence. This reflected emission follows the variability of the compact object with a delay approximately equal to the orbital radius divided by the speed of light. This provides the possibility of measuring the orbital radius and thus substantially refining the compact object mass determination compared to using optical data alone. We demonstrate that it may be feasible to measure the time delay between the direct and reflected emission using cross-correlation of the light curves observed near the Kalpha line and above the K-edge of neutral iron. In the case of Cyg X-1, the time delay measurement is feasible with a 300--1000 ksec observation by a telescope with a 1000 cm^2 effective area near 6.4 keV and with a ~5eV energy resolution. With longer exposures, it may be possible to obtain mass constraints even if an X-ray source in the binary system lacks an optical counterpart.

A. Vikhlinin

1999-06-09T23:59:59.000Z

274

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.

275

Controlling X-rays With Light  

SciTech Connect (OSTI)

Ultrafast x-ray science is an exciting frontier that promises the visualization of electronic, atomic and molecular dynamics on atomic time and length scales. A largelyunexplored area of ultrafast x-ray science is the use of light to control how x-rays interact with matter. In order to extend control concepts established for long wavelengthprobes to the x-ray regime, the optical control field must drive a coherent electronic response on a timescale comparable to femtosecond core-hole lifetimes. An intense field is required to achieve this rapid response. Here an intense optical control pulse isobserved to efficiently modulate photoelectric absorption for x-rays and to create an ultrafast transparency window. We demonstrate an application of x-ray transparencyrelevant to ultrafast x-ray sources: an all-photonic temporal cross-correlation measurement of a femtosecond x-ray pulse. The ability to control x-ray/matterinteractions with light will create new opportunities at current and next-generation x-ray light sources.

Glover, Ernie; Hertlein, Marcus; Southworth, Steve; Allison, Tom; van Tilborg, Jeroen; Kanter, Elliot; Krassig, B.; Varma, H.; Rude, Bruce; Santra, Robin; Belkacem, Ali; Young, Linda

2010-08-02T23:59:59.000Z

276

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

277

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

SciTech Connect (OSTI)

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

278

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

279

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.

280

On the mechanism of NO selective catalytic reduction by hydrocarbons over Cu-ZSM-5 via X-ray absorption spectroscopic study  

SciTech Connect (OSTI)

An understanding of the catalytic mechanism of NO{sub x} reduction is critical for the development of next-generation high-fuel efficiency, low-emission vehicles. This paper compiles the investigations in recent years on the mechanism of NO selective catalytic reduction (SCR) by hydrocarbon over Cu-ZSM-5. The studies were focused on the oxidation state and coordination chemistry of the exchanged Cu as the active site during the catalytic reaction using X-ray absorption spectroscopic (XAS) techniques, mainly XANES and EXAFS. Their experiment demonstrated the existence of a redox mechanism which involves cyclic switching of the oxidation states between Cu(II) and Cu(I) in an oxygen-rich gas mixture under elevated temperature. The authors also observed the coordination structural change of copper ion in ZSM-5 accompanying the change of oxidation state. A correlation between cuprous ion concentration and catalytic activity was found in NO SCR by propene. The impact of another two hydrocarbons, propane and methane, on the copper redox behavior also appears to correlate to catalytic activities in the respective mixtures. Discussions on the nature of the active sites and the mechanism of SCR are presented based on the XAS data analysis. The similarity and difference of the physical properties of copper ion between NO catalytic decomposition and NO SCR are also discussed.

Liu, D.J. [AlliedSignal Inc., Des Plaines, IL (United States)] [AlliedSignal Inc., Des Plaines, IL (United States); Robota, H.J. [ASEC, Tulsa, OK (United States)] [ASEC, Tulsa, OK (United States)

1999-04-08T23:59:59.000Z

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

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

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

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

282

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

SciTech Connect (OSTI)

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

283

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 (OSTI)

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

284

Time-resolved soft-x-ray spectroscopy of a magnetic octupole transition in nickel-like xenon, cesium, and barium ions  

SciTech Connect (OSTI)

A microcalorimeter with event mode capability for time-resolved soft-x-ray spectroscopy, and a high-resolution flat-field EUV spectrometer have been employed at the Livermore EBIT-I electron beam ion trap for observations and wavelength measurements of M1, E2, and M3 decays of long-lived levels in the Ni-like ions Xe{sup 26+}, Cs{sup 27+}, and Ba{sup 28+}. Of particular interest is the lowest excited level, 3d{sup 9}4s {sup 3}D{sub 3}, which can only decay via a magnetic octupole (M3) transition. For this level in Xe an excitation energy of (590.40 {+-} 0.03eV) and a level lifetime of (11.5 {+-} 0.5 ms) have been determined.

Trabert, E; Beiersdorfer, P; Brown, G V; Boyce, K; Kelley, R L; Kilbourne, C A; Porter, F S; Szymkowiak, A

2005-11-11T23:59:59.000Z

285

X-Ray Data Booklet X-RAY DATA BOOKLET  

E-Print Network [OSTI]

X-Ray Data Booklet X-RAY DATA BOOKLET Center for X-ray Optics and Advanced Light Source Lawrence Berkeley National Laboratory Introduction X-Ray Properties of Elements Electron Binding Energies X-Ray Levels of Few Electron Ions Now Available Order X-Ray Data Booklet http://xdb.lbl.gov/ (1 of 3) [2

Meagher, Mary

286

Photosynthesis and structure of electroless Ni-P films by synchrotron x-ray irradiation  

SciTech Connect (OSTI)

The authors describe an electroless deposition method for thin films, based on the irradiation by an x-ray beam emitted by a synchrotron source. Specifically, Ni-P films were deposited at room temperature. This synthesis is a unique combination of photochemical and electrochemical processes. The influence of the pH value on the formation and structural properties of the films was examined by various characterization tools including scanning electron microscopy, x-ray diffraction, and x-ray absorption spectroscopy. Real time monitoring of the deposition process by coherent x-ray microscopy reveals that the formation of hydrogen bubbles leads to a self-catalysis effect without a preexisting catalyst. The mechanisms underlying the deposition process are discussed in details.

Hsu, P.-C.; Wang, C.-H.; Yang, T.-Y.; Hwu, Y.-K.; Lin, C.-S.; Chen, C.-H.; Chang, L.-W.; Seol, S.-K.; Je, J.-H.; Margaritondo, G. [Institute of Physics, Academia Sinica, NanKang, Taipei 115, Taiwan and Department of Materials Science and Engineering, National Taiwan University, Taipei 106, Taiwan (China); Institute of Physics, Academia Sinica, NanKang, Taipei 115, Taiwan (China); Institute of Physics, Academia Sinica, NanKang, Taipei 115, Taiwan (China); Department of Engineering and System Science, National Tsing Hua University, Hsinchu, 300, Taiwan (China) and Institute of Optoelectronic Sciences, National Taiwan Ocean University, Keelung 202, Taiwan (China); Department of Materials Science and Engineering, National Taiwan University, Taipei 106, Taiwan (China); Kinsus Interconnect Technology Co., Taoyuang 327, Taiwan (China); Department of Materials Science and Optoelectronic Engineering, National Sun Yat-Sen University, Kaoshung 804, Taiwan (China); X-ray Imaging Center, Pohang University of Science and Technology, Pohang 790-784 (Korea, Republic of) and Department of Materials Science and Engineering, Pohang University of Science and Technology, Pohang 790-784 (Korea); Ecole Polytechnique Federale de Lausanne (EPFL), CH-1015 Lausanne (Switzerland)

2007-05-15T23:59:59.000Z

287

Standard test method for analysis of uranium and thorium in soils by energy dispersive X-Ray fluorescence spectroscopy  

E-Print Network [OSTI]

1.1 This test method covers the energy dispersive X-ray fluorescence (EDXRF) spectrochemical analysis of trace levels of uranium and thorium in soils. Any sample matrix that differs from the general ground soil composition used for calibration (that is, fertilizer or a sample of mostly rock) would have to be calibrated separately to determine the effect of the different matrix composition. 1.2 The analysis is performed after an initial drying and grinding of the sample, and the results are reported on a dry basis. The sample preparation technique used incorporates into the sample any rocks and organic material present in the soil. This test method of sample preparation differs from other techniques that involve tumbling and sieving the sample. 1.3 Linear calibration is performed over a concentration range from 20 to 1000 ?g per gram for uranium and thorium. 1.4 The values stated in SI units are to be regarded as the standard. The inch-pound units in parentheses are for information only. 1.5 This standard...

American Society for Testing and Materials. Philadelphia

2011-01-01T23:59:59.000Z

288

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

SciTech Connect (OSTI)

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

289

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

290

Pressure-tuning spectroscopy of charge-transfer salts. X-ray crystallography and comparative studies in solution and in the solid state  

SciTech Connect (OSTI)

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

291

Profiling of the SiO2 -SiC Interface Using X-ray Photoelectron Spectroscopy R. N. Ghosh  

E-Print Network [OSTI]

energy loss spectroscopy, have revealed a 1.5-6 nm thick layer with a monotonically decaying C 4 School of Electrical & Computer Engineering, Purdue Univ., W. Lafayette, IN 47907 ABSTRACT techniques have been utilized to study this problem. Atomic H3.7.1 Mat. Res. Soc. Symp. Vol. 640 © 2001

Ghosh, Ruby N.

292

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 (OSTI)

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

293

E-Print Network 3.0 - absorption spectroscopy characterization...  

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

and Restoration Technologies 87 Terahertz Time-Domain Spectroscopy Study of Silica Aerogels and Adsorbed Molecular Jiangquan Zhang and D. Grischkowsky* Summary: absorption...

294

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

295

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

296

Chest x-Rays  

Broader source: Energy.gov [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.

297

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

298

X-ray induced optical reflectivity  

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

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

299

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

300

Scanning Transmission X-ray Microscopy: Applications in Atmospheric Aerosol Research  

SciTech Connect (OSTI)

Scanning transmission x-ray microscopy (STXM) combines x-ray microscopy and near edge x-ray absorption fine structure spectroscopy (NEXAFS). This combination provides spatially resolved bonding and oxidation state information. While there are reviews relevant to STXM/NEXAFS applications in other environmental fields (and magnetic materials) this chapter focuses on atmospheric aerosols. It provides an introduction to this technique in a manner approachable to non-experts. It begins with relevant background information on synchrotron radiation sources and a description of NEXAFS spectroscopy. The bulk of the chapter provides a survey of STXM/NEXAFS aerosol studies and is organized according to the type of aerosol investigated. The purpose is to illustrate the current range and recent growth of scientific investigations employing STXM-NEXAFS to probe atmospheric aerosol morphology, surface coatings, mixing states, and atmospheric processing.

Moffet, Ryan C.; Tivanski, Alexei V.; Gilles, Mary K.

2011-01-20T23:59:59.000Z

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.


301

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

302

Water adsorption, solvation and deliquescence of alkali halide thin films on SiO2 studied by ambient pressure X-ray photoelectron spectroscopy  

SciTech Connect (OSTI)

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

303

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 (OSTI)

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

304

A promising concept for using near-surface measuring angles in angle-resolved x-ray photoelectron spectroscopy considering elastic scattering effects  

SciTech Connect (OSTI)

The increasing number of applications of very thin films requires both reliable thin-layer and interface characterization. A powerful method for characterization in the nanometer thickness range is the angle-resolved x-ray photoelectron spectroscopy (ARXPS). This is a nondestructive depth-profiling method, which can provide elemental content as well as chemical information. Two of the drawbacks of ARXPS are, that it requires dedicated mathematical modeling and that, at least up until now, its use has been restricted away from near-surface angles. In this paper we present a method for the mathematical description of a few, hitherto unaccounted, measurement effects in order to improve the simulations of ARXPS data for complex surface structures. As an immediate application, we propose a simple algorithm to consider the effects of elastic scattering in the standard ARXPS data interpretation, which in principle would allow the use of the whole angular range for the analysis; thus leading to a significant increase in the usable information content from the measurements. The potential of this approach is demonstrated with model calculations for a few thin film examples.

Oswald, S.; Oswald, F. [IFW Dresden, Postfach 270116, D-01171 Dresden (Germany)

2011-02-01T23:59:59.000Z

305

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

306

High resolution soft x-ray spectroscopy of low Z K-shell emission from laser-produced plasmas  

SciTech Connect (OSTI)

A large radius, R = 44.3 m, High Resolution Grating Spectrometer (HRGS) with 2400 line/mm variable line spacing has been designed for laser-produced plasma experiments conducted at the Lawrence Livermore National Laboratory Jupiter Laser Facility. The instrument has been run with a low-noise, charge-coupled device detector to record high signal-to-noise spectra in the 10-50 {angstrom} wavelength range. The instrument can be run with a 10-20 {micro}m wide slit to achieve the best spectral resolving power, approaching 1000 and similar to crystal spectrometers at 12-20 {angstrom}, or in slitless operation with a small symmetrical emission source. We describe preliminary spectra emitted from various H-like and He-like low Z ion plasmas heated by 100-500 ps (FWHM), 527 nm wavelength laser pulses. This instrument can be developed as a useful spectroscopy platform relevant to laboratory-based astrophysics as well as high energy density plasma studies.

Dunn, J; Magee, E W; Shepherd, R; Chen, H; Hansen, S B; Moon, S J; Brown, G V; Gu, M; Beiersdorfer, P; Purvis, M A

2008-05-21T23:59:59.000Z

307

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

SciTech Connect (OSTI)

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

Hager, J. D., E-mail: hager@lanl.gov; Lanier, N. E.; Kline, J. L.; Flippo, K. A. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Bruns, H. C.; Schneider, M.; Saculla, M.; McCarville, T. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States)

2014-11-15T23:59:59.000Z

308

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

309

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

310

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

311

Transient absorption spectroscopy of laser shocked explosives  

SciTech Connect (OSTI)

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

Mcgrane, Shawn D [Los Alamos National Laboratory; Dang, Nhan C [Los Alamos National Laboratory; Whitley, Von H [Los Alamos National Laboratory; Bolome, Cindy A [Los Alamos National Laboratory; Moore, D S [Los Alamos National Laboratory

2010-01-01T23:59:59.000Z

312

Tools for a Theoretical X-ray Beamline J. J. Rehr*  

E-Print Network [OSTI]

Tools for a Theoretical X-ray Beamline J. J. Rehr* Department of Physics University of Washington, France 22 October 2010 #12;X-ray Spectroscopy Beamline #12;Tools for a Theoretical X-ray Beamline · GOAL Theoretical X-ray Beamline: 2. Tools for EXAFS and XANES, EELS, XMCD, ... 3. DFT/MD-TOOLS 4. Next generation

Botti, Silvana

313

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

314

Inner-Shell Excitation Spectroscopy of Fused-Ring Aromatic Molecules by Electron Energy Loss and X-ray Raman Techniques  

E-Print Network [OSTI]

recorded under scattering conditions where electric dipole transitions dominate (2.5 keV residual energy aromatics in bulk samples that are opaque to soft X-rays, such as coals and heavy hydrocarbon deposits. 1

Hitchcock, Adam P.

315

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 (OSTI)

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

316

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

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

A partial sampling of these techniques includes: Absorption spectroscopy Atomic absorption... 109 3.4 Spectroscopic Sensors Spectroscopy is the scientific study of...

317

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 (OSTI)

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

318

X-ray diffraction analysis and scanning micro-Raman spectroscopy of structural irregularities and strains deep inside the multilayered InGaN/GaN heterostructure  

SciTech Connect (OSTI)

High-resolution X-ray diffraction analysis and scanning confocal Raman spectroscopy are used to study the spatial distribution of strains in the In{sub x}Ga{sub 1-x}N/GaN layers and structural quality of these layers in a multilayered light-emitting diode structure produced by metal-organic chemical vapor deposition onto (0001)-oriented sapphire substrates. It is shown that elastic strains almost completely relax at the heterointerface between the thick GaN buffer layer and In{sub x}Ga{sub 1-x}N/GaN buffer superlattice. It is established that the GaN layers in the superlattice are in a stretched state, whereas the alloy layers are in a compressed state. In magnitude, the stretching strains in the GaN layers are lower than the compressive strains in the InGaN layers. It is shown that, as compared to the buffer layers, the layers of the superlattice contain a smaller number of dislocations and the distribution of dislocations is more randomly disordered. In micro-Raman studies on scanning through the thickness of the multilayered structure, direct evidence is obtained for the asymmetric gradient distributions of strains and crystal imperfections of the epitaxial nitride layers along the direction of growth. It is shown that the emission intensity of the In{sub x}Ga{sub 1-x}N quantum well is considerably (more than 30 times) higher than the emission intensity of the GaN barrier layers, suggesting the high efficiency of trapping of charge carriers by the quantum well.

Strelchuk, V. V., E-mail: Strelch@isp.kiev.ua; Kladko, V. P.; Avramenko, E. A.; Kolomys, O. F.; Safryuk, N. V.; Konakova, R. V. [National Academy of Sciences of Ukraine, Lashkaryov Institute of Semiconductor Physics (Ukraine); Yavich, B. S., E-mail: byavich@soptel.ru [ZAO Svetlana-Optoelectronics (Russian Federation); Valakh, M. Ya.; Machulin, V. F.; Belyaev, A. E. [National Academy of Sciences of Ukraine, Lashkaryov Institute of Semiconductor Physics (Ukraine)

2010-09-15T23:59:59.000Z

319

absorption spectroscopy study: Topics by E-print Network  

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

14 15 16 17 18 19 20 21 22 23 24 25 Next Page Last Page Topic Index 1 On Automatic Absorption Detection for Imaging Spectroscopy: A Comparative Study Computer Technologies and...

320

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

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

Development of soft X-ray polarized light beamline on Indus-2 synchrotron radiation source  

SciTech Connect (OSTI)

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

322

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

323

absorption spectroscopy studies: Topics by E-print Network  

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

absorption spectroscopy studies First Page Previous Page 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 Next Page Last Page Topic Index 1 On Automatic Absorption...

324

X-ray and synchrotron studies of porous silicon  

SciTech Connect (OSTI)

The results of comprehensive studies of layers of porous silicon of different conductivity types, grown by anodizing standard Si(111) substrates in an electrolyte based on fluoric acid and ethanol with the addition of 5% of iodine and kept in air for a long time, are discussed. Measurements are performed by scanning electron microscopy, high-resolution X-ray diffraction, and ultrasoft X-ray spectroscopy using synchrotron radiation. The structural parameters of the layers (thickness, strain, and porosity) and atomic and chemical composition of the porous-silicon surface are determined. It is found that an oxide layer 1.5-2.3-nm thick is formed on the surface of the silicon skeleton. The near-edge fine structure of the Si 2p absorption spectrum of this layer corresponds to the fine structure of the 2p spectrum of well coordinated SiO{sub 2}. In this case, the fine structure in the Si 2p-edge absorption region of the silicon skeleton is identical to that of the 2p absorption spectrum of crystalline silicon.

Sivkov, V. N., E-mail: svn@dm.komisc.ru [Russian Academy of Sciences, Komi Scientific Center, Ural Branch (Russian Federation); Lomov, A. A. [Russian Academy of Sciences, Physical-Technological Institute (Russian Federation)] [Russian Academy of Sciences, Physical-Technological Institute (Russian Federation); Vasil'ev, A. L. [Russian Academy of Sciences, Shubnikov Institute of Crystallography (Russian Federation)] [Russian Academy of Sciences, Shubnikov Institute of Crystallography (Russian Federation); Nekipelov, S. V. [Komi State Pedagogical Institute (Russian Federation)] [Komi State Pedagogical Institute (Russian Federation); Petrova, O. V. [Russian Academy of Sciences, Komi Scientific Center, Ural Branch (Russian Federation)] [Russian Academy of Sciences, Komi Scientific Center, Ural Branch (Russian Federation)

2013-08-15T23:59:59.000Z

325

Silicon drift detector based X-ray spectroscopy diagnostic system for the study of non-thermal electrons at Aditya tokamak  

SciTech Connect (OSTI)

Silicon drift detector based X-ray spectrometer diagnostic was developed to study the non-thermal electron for Aditya tokamak plasma. The diagnostic was mounted on a radial mid plane port at the Aditya. The objective of diagnostic includes the estimation of the non-thermal electron temperature for the ohmically heated plasma. Bi-Maxwellian plasma model was adopted for the temperature estimation. Along with that the study of high Z impurity line radiation from the ECR pre-ionization experiments was also aimed. The performance and first experimental results from the new X-ray spectrometer system are presented.

Purohit, S., E-mail: pshishir@ipr.res.in; Joisa, Y. S.; Raval, J. V.; Ghosh, J.; Tanna, R.; Shukla, B. K.; Bhatt, S. B. [Institute for Plasma Research, Bhat, Gandhinagar 382 428 (India)

2014-11-15T23:59:59.000Z

326

Laser wakefield generated X-ray probe for femtosecond time-resolved measurements of ionization states of warm dense aluminum  

SciTech Connect (OSTI)

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

327

Multiplexed absorption tomography with calibration-free wavelength modulation spectroscopy  

SciTech Connect (OSTI)

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

328

CHANDRA X-RAY SPECTROSCOPY OF THE FOCUSED WIND IN THE CYGNUS X-1 SYSTEM. I. THE NONDIP SPECTRUM IN THE LOW/HARD STATE  

E-Print Network [OSTI]

We present analyses of a 50 ks observation of the supergiant X-ray binary system Cygnus X-1 (Cyg X-1)/HDE226868 taken with the Chandra High Energy Transmission Grating Spectrometer (HETGS). Cyg X-1 was in its spectrally ...

Hanke, Manfred

329

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 (OSTI)

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

330

Beam damage of poly(vinyl chloride) [PVC] as observed by x-ray...  

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

damage of poly(vinyl chloride) PVC as observed by x-ray photoelectron spectroscopy at 143 K, 303 K and 373 K. Beam damage of poly(vinyl chloride) PVC as observed by x-ray...

331

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

332

Fluctuation X-Ray Scattering  

SciTech Connect (OSTI)

The work supported by the grant was aimed at developing novel methods of finding the structures of biomolecules using x-rays from novel sources such as the x-ray free electron laser and modern synchrotrons

Saldin, PI: D. K.; Co-I's: J. C. H. Spence and P. Fromme

2013-01-25T23:59:59.000Z

333

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

334

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

335

Polarized Range-Extended X-Ray Absorption Spectroscopy of Oriented Photosystem Ii Membranes in the S (1) State  

SciTech Connect (OSTI)

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

336

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

337

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

E-Print Network [OSTI]

of the interaction of the carboxylate with lithium; this isinteraction strengths of the monovalent cations of sodium, potassium, and lithiumlithium acetate revealing distinct shifts between the cations, indicative of preferential interactions.

Uejio, Janel S.

2008-01-01T23:59:59.000Z

338

On the importance of nuclear quantum motions in near edge x-ray absorption fine structure (NEXAFS) spectroscopy of molecules  

SciTech Connect (OSTI)

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

339

Revisiting the localization of Zn2+ cations sorbed on pathological apatite calcifications made through X-ray absorption spectroscopy  

E-Print Network [OSTI]

bones Accepted in Osteoporosis International F. E. Sowrey,to characterise bones Osteoporosis International, in press.such as arthrosis or osteoporosis [3]. Of note, among the

Bazin, D.

2010-01-01T23:59:59.000Z

340

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

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

USE OF MICRO X-RAY ABSORPTION SPECTROSCOPY AND DIFFRACTION TO DELINEATE Cr(VI) SPECIATION IN COPR  

SciTech Connect (OSTI)

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

342

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

343

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 (OSTI)

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

344

Delayed Ultrafast X-ray Auger Probing (DUXAP) of Nucleobase Ultraviolet Photoprotection  

E-Print Network [OSTI]

We present a new method for ultrafast spectroscopy of molecular photoexcited dynamics. The technique uses a pair of femtosecond pulses: a photoexcitation pulse initiating excited state dynamics followed by a soft x-ray (SXR) probe pulse that core ionizes certain atoms inside the molecule. We observe the Auger decay of the core hole as a function of delay between the photoexcitation and SXR pulses. The core hole decay is particularly sensitive to the local valence electrons near the core and shows new types of propensity rules, compared to dipole selection rules in SXR absorption or emission spectroscopy. We apply the delayed ultrafast x-ray Auger probing (DUXAP) method to the specific problem of nucleobase photoprotection to demonstrate its potential. The ultraviolet photoexcited \\pi\\pi* states of nucleobases are prone to chemical reactions with neighboring bases. To avoid this, the single molecules funnel the \\pi\\pi* population to lower lying electronic states on an ultrafast timescale under violation of the...

McFarland, B K; Miyabe, S; Tarantelli, F; Aguilar, A; Berrah, N; Bostedt, C; Bozek, J; Bucksbaum, P H; Castagna, J C; Coffee, R; Cryan, J; Fang, L; Feifel, R; Gaffney, K; Glownia, J; Martinez, T; Mucke, M; Murphy, B; Natan, A; Osipov, T; Petrovic, V; Schorb, S; Schultz, Th; Spector, L; Swiggers, M; Tenney, I; Wang, S; White, W; White, J; Gühr, M

2013-01-01T23:59:59.000Z

345

A new spectrometer design for the x-ray spectroscopy of laser-produced plasmas with high (sub-ns) time resolution  

SciTech Connect (OSTI)

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

346

Soft X-Ray Spectroscopic Study of Dense Strontium-Doped Lanthanum Manganite Cathodes for Solid Oxide Fuel Cell Applications  

SciTech Connect (OSTI)

The evolution of the Mn charge state, chemical composition, and electronic structure of La{sub 0.8}Sr{sub 0.2}MnO{sub 3} (LSMO) cathodes during the catalytic activation of solid oxide fuel cell (SOFC) has been studies using X-ray spectroscopy of as-processed, exposed, and activated dense thin LSMO films. Comparison of O K-edge and Mn L{sub 3,2}-edge X-ray absorption spectra from the different stages of LSMO cathodes revealed that the largest change after the activation occurred in the Mn charge state with little change in the oxygen environment. Core-level X-ray photoemission spectroscopy and Mn L{sub 3} resonant photoemission spectroscopy studies of exposed and as-processed LSMO determined that the SOFC environment (800 C ambient pressure of O{sub 2}) alone results in La deficiency (severest near the surface with Sr doping >0.55) and a stronger Mn{sup 4+} contribution, leading to the increased insulating character of the cathode prior to activation. Meanwhile, O K-edge X-ray absorption measurements support Sr/La enrichment nearer the surface, along with the formation of mixed Sr{sub x}Mn{sub y}O{sub z} and/or passive MnO{sub x} and SrO species.

L Piper; A Preston; S Cho; A DeMasi; J Laverock; K Smith; L Miara; J Davis; S Basu; et al.

2011-12-31T23:59:59.000Z

347

Broadband high resolution X-ray spectral analyzer  

DOE Patents [OSTI]

A broad bandwidth high resolution x-ray fluorescence spectrometer has a performance that is superior in many ways to those currently available. It consists of an array of 4 large area microcalorimeters with 95% quantum efficiency at 6 keV and it produces x-ray spectra between 0.2 keV and 7 keV with an energy resolution of 7 to 10 eV. The resolution is obtained at input count rates per array element of 10 to 50 Hz in real-time, with analog pulse processing and thermal pile-up rejection. This performance cannot be matched by currently available x-ray spectrometers. The detectors are incorporated into a compact and portable cryogenic refrigerator system that is ready for use in many analytical spectroscopy applications as a tool for x-ray microanalysis or in research applications such as laboratory and astrophysical x-ray and particle spectroscopy.

Silver, Eric H. (Berkeley, CA); Legros, Mark (Berkeley, CA); Madden, Norm W. (Livermore, CA); Goulding, Fred (Lafayette, CA); Landis, Don (Pinole, CA)

1998-01-01T23:59:59.000Z

348

X-ray lithography source  

DOE Patents [OSTI]

A high-intensity, inexpensive X-ray source for X-ray lithography for the production of integrated circuits is disclosed. Foil stacks are bombarded with a high-energy electron beam of 25 to 250 MeV to produce a flux of soft X-rays of 500 eV to 3 keV. Methods of increasing the total X-ray power and making the cross section of the X-ray beam uniform are described. Methods of obtaining the desired X-ray-beam field size, optimum frequency spectrum and eliminating the neutron flux are all described. A method of obtaining a plurality of station operation is also described which makes the process more efficient and economical. The satisfying of these issues makes transition radiation an excellent moderate-priced X-ray source for lithography. 26 figures.

Piestrup, M.A.; Boyers, D.G.; Pincus, C.

1991-12-31T23:59:59.000Z

349

X-ray lithography source  

DOE Patents [OSTI]

A high-intensity, inexpensive X-ray source for X-ray lithography for the production of integrated circuits. Foil stacks are bombarded with a high-energy electron beam of 25 to 250 MeV to produce a flux of soft X-rays of 500 eV to 3 keV. Methods of increasing the total X-ray power and making the cross section of the X-ray beam uniform are described. Methods of obtaining the desired X-ray-beam field size, optimum frequency spectrum and elminating the neutron flux are all described. A method of obtaining a plurality of station operation is also described which makes the process more efficient and economical. The satisfying of these issues makes transition radiation an exellent moderate-priced X-ray source for lithography.

Piestrup, Melvin A. (Woodside, CA); Boyers, David G. (Mountain View, CA); Pincus, Cary (Sunnyvale, CA)

1991-01-01T23:59:59.000Z

350

Molecular shock response of explosives: electronic absorption spectroscopy  

SciTech Connect (OSTI)

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

351

X-Ray Diagnostics  

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

AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr May JunDatastreamsmmcrcalgovInstrumentsrucLasDelivered energy consumption byAbout SRNL Home SRNL main campusMore than 20X-Ray Diagnostics

352

X-ray compass for determining device orientation  

DOE Patents [OSTI]

An apparatus and method for determining the orientation of a device with respect to an x-ray source. In one embodiment, the present invention is coupled to a medical device in order to determine the rotational orientation of the medical device with respect to the x-ray source. In such an embodiment, the present invention is comprised of a scintillator portion which is adapted to emit photons upon the absorption of x-rays emitted from the x-ray source. An x-ray blocking portion is coupled to the scintillator portion. The x-ray blocking portion is disposed so as to vary the quantity of x-rays which penetrate the scintillator portion based upon the particular rotational orientation of the medical device with respect to the x-ray source. A photon transport mechanism is also coupled to the scintillator portion. The photon transport mechanism is adapted to pass the photons emitted from the scintillator portion to an electronics portion. By analyzing the quantity of the photons, the electronics portion determines the rotational orientation of the medical device with respect to the x-ray source.

Da Silva, Luiz B. (Danville, CA); Matthews, Dennis L. (Moss Beach, CA); Fitch, Joseph P. (Livermore, CA); Everett, Matthew J. (Pleasanton, CA); Colston, Billy W. (Livermore, CA); Stone, Gary F. (Livermore, CA)

1999-01-01T23:59:59.000Z

353

X-ray compass for determining device orientation  

DOE Patents [OSTI]

An apparatus and method for determining the orientation of a device with respect to an x-ray source are disclosed. In one embodiment, the present invention is coupled to a medical device in order to determine the rotational orientation of the medical device with respect to the x-ray source. In such an embodiment, the present invention is comprised of a scintillator portion which is adapted to emit photons upon the absorption of x-rays emitted from the x-ray source. An x-ray blocking portion is coupled to the scintillator portion. The x-ray blocking portion is disposed so as to vary the quantity of x-rays which penetrate the scintillator portion based upon the particular rotational orientation of the medical device with respect to the x-ray source. A photon transport mechanism is also coupled to the scintillator portion. The photon transport mechanism is adapted to pass the photons emitted from the scintillator portion to an electronics portion. By analyzing the quantity of the photons, the electronics portion determines the rotational orientation of the medical device with respect to the x-ray source. 25 figs.

Da Silva, L.B.; Matthews, D.L.; Fitch, J.P.; Everett, M.J.; Colston, B.W.; Stone, G.F.

1999-06-15T23:59:59.000Z

354

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 (OSTI)

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

355

On the nature of the z=0 X-ray absorbers: II. The contrast between local and AGN host galaxy absorption  

E-Print Network [OSTI]

We search for highly-ionized gas near three AGN host galaxies using the Chandra low-energy transmission grating spectrograph. Strong absorption lines from such gas are seen at z=0, most likely from one or more of the following components: (1) a Galactic corona, (2) the Local Group medium, and (3) an extended warm-hot intergalactic medium (WHIM) filament passing through our local overdensity. Since AGNs reside within host galaxies that are also expected to sit within cosmically overdense regions, similar absorption resulting from these three components should appear at the AGN redshifts as well. However, no such absorption is seen. The lack of strong absorption lines is likely a result of the gas in these host galaxies and surrounding galaxy clusters being much hotter, and hence more highly ionized, than the gas in the Local Group+Galaxy system. We conclude that WHIM filaments produce no measurable absorption lines at the AGN redshifts, and therefore contribute at most a small fraction of the observed z=0 warm-hot gas.

Rik J. Williams; Smita Mathur; Fabrizio Nicastro

2007-09-24T23:59:59.000Z

356

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

357

Laser photothermal spectroscopy of light-induced absorption  

SciTech Connect (OSTI)

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

358

Time resolved ultraviolet absorption spectroscopy of pulsed fluorocarbon plasmas  

E-Print Network [OSTI]

Time resolved ultraviolet absorption spectroscopy of pulsed fluorocarbon plasmas Brett A. Cruden.1063/1.1334936 I. INTRODUCTION The study of fluorocarbon plasmas is of great interest for their applications in silicon dioxide etching.1,2 Recently, at- tention has been paid to using fluorocarbon plasmas to pro- duce

Gleason, Karen K.

359

E-Print Network 3.0 - absorption spectroscopies progress Sample...  

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

360

E-Print Network 3.0 - atomic absorption spectroscopy Sample Search...  

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

Search Powered by Explorit Topic List Advanced Search Sample search results for: atomic absorption spectroscopy Page: << < 1 2 3 4 5 > >> 1 Xray Absorption Near Edge...

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 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

362

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

363

High resolution, multiple-energy linear sweep detector for x-ray imaging  

DOE Patents [OSTI]

Apparatus is disclosed for generating plural electrical signals in a single scan in response to incident X-rays received from an object. Each electrical signal represents an image of the object at a different range of energies of the incident X-rays. The apparatus comprises a first X-ray detector, a second X-ray detector stacked upstream of the first X-ray detector, and an X-ray absorber stacked upstream of the first X-ray detector. The X-ray absorber provides an energy-dependent absorption of the incident X-rays before they are incident at the first X-ray detector, but provides no absorption of the incident X-rays before they are incident at the second X-ray detector. The first X-ray detector includes a linear array of first pixels, each of which produces an electrical output in response to the incident X-rays in a first range of energies. The first X-ray detector also includes a circuit that generates a first electrical signal in response to the electrical output of each of the first pixels. The second X-ray detector includes a linear array of second pixels, each of which produces an electrical output in response to the incident X-rays in a second range of energies, broader than the first range of energies. The second X-ray detector also includes a circuit that generates a second electrical signal in response to the electrical output of each of the second pixels. 12 figs.

Perez-Mendez, V.; Goodman, C.A.

1996-08-20T23:59:59.000Z

364

High resolution, multiple-energy linear sweep detector for x-ray imaging  

DOE Patents [OSTI]

Apparatus for generating plural electrical signals in a single scan in response to incident X-rays received from an object. Each electrical signal represents an image of the object at a different range of energies of the incident X-rays. The apparatus comprises a first X-ray detector, a second X-ray detector stacked upstream of the first X-ray detector, and an X-ray absorber stacked upstream of the first X-ray detector. The X-ray absorber provides an energy-dependent absorption of the incident X-rays before they are incident at the first X-ray detector, but provides no absorption of the incident X-rays before they are incident at the second X-ray detector. The first X-ray detector includes a linear array of first pixels, each of which produces an electrical output in response to the incident X-rays in a first range of energies. The first X-ray detector also includes a circuit that generates a first electrical signal in response to the electrical output of each of the first pixels. The second X-ray detector includes a linear array of second pixels, each of which produces an electrical output in response to the incident X-rays in a second range of energies, broader than the first range of energies. The second X-ray detector also includes a circuit that generates a second electrical signal in response to the electrical output of each of the second pixels.

Perez-Mendez, Victor (Berkeley, CA); Goodman, Claude A. (Kensington, CA)

1996-01-01T23:59:59.000Z

365

Miniature x-ray source  

DOE Patents [OSTI]

A miniature x-ray source capable of producing broad spectrum x-ray emission over a wide range of x-ray energies. The miniature x-ray source comprises a compact vacuum tube assembly containing a cathode, an anode, a high voltage feedthru for delivering high voltage to the anode, a getter for maintaining high vacuum, a connection for an 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 highly x-ray transparent and made, for example, from boron nitride. The compact size and potential for remote operation allows the x-ray source, for example, to be placed adjacent to a material sample undergoing analysis or in proximity to the region to be treated for medical applications.

Trebes, James E. (Livermore, CA); Stone, Gary F. (Livermore, CA); Bell, Perry M. (Tracy, CA); Robinson, Ronald B. (Modesto, CA); Chornenky, Victor I. (Minnetonka, MN)

2002-01-01T23:59:59.000Z

366

Communication: Systematic shifts of the lowest unoccupied molecular orbital peak in x-ray absorption for a series of 3d metal porphyrins  

E-Print Network [OSTI]

-ray absorption for a series of 3d metal porphyrins J. M. García-Lastra,1,2,a P. L. Cook,3 F. J. Himpsel,3 and A 20 October 2010 Porphyrins are widely used as dye molecules in solar cells. Knowing the energies of their frontier orbitals is crucial for optimizing the energy level structure of solar cells. We use near edge x

367

X-ray fluorescence mapping  

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

368

E-Print Network 3.0 - absorption spectroscopy Sample Search Results  

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

369

E-Print Network 3.0 - absorption spectroscopy q-xas Sample Search...  

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

370

X-ray Fading and Expansion in the "Miniature Supernova Remnant" of GK Persei  

E-Print Network [OSTI]

We report on a second epoch of Chandra X-ray imaging spectroscopy of the spatially-resolved old nova remnant GK Persei. An ACIS-S3 observation of 97.4 ks was conducted in November 2013 after a lapse of 13.8 years from the last visit in 2000. The X-ray emitting nebula appeared more faint and patchy compared with the first epoch. The flux decline was particularly evident in fainter regions and the mean decline was 30-40 % in the 0.5-1.2 keV energy band. A typical expansion of the brightest part of the remnant was 1.9 arcsec, which corresponds to an expansion rate of 0.14 arcsec yr^{-1}. The soft X-ray spectra extracted from both the 2000 and 2013 data can be explained by a non-equilibrium ionization collisional plasma model convolved with interstellar absorption, though do not allow us to constrain the origin of the flux evolution. The plasma temperature has not significantly evolved since the 2000 epoch and we conclude that the fading of the X-ray emission is due largely to expansion. This implies that recent ...

Takei, D; Yamaguchi, H; Slane, P; Uchiyama, Y; Katsuda, S

2015-01-01T23:59:59.000Z

371

E-Print Network 3.0 - ambient-pressure x-ray photoelectron Sample...  

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

372

PROBING DYNAMICS OF ELECTRON ACCELERATION WITH RADIO AND X-RAY SPECTROSCOPY, IMAGING, AND TIMING IN THE 2002 APRIL 11 SOLAR FLARE  

SciTech Connect (OSTI)

Based on detailed analysis of radio and X-ray observations of a flare on 2002 April 11 augmented by realistic three-dimensional modeling, we have identified a radio emission component produced directly at the flare acceleration region. This acceleration region radio component has distinctly different (1) spectrum, (2) light curves, (3) spatial location, and, thus, (4) physical parameters from those of the separately identified trapped or precipitating electron components. To derive evolution of physical parameters of the radio sources we apply forward fitting of the radio spectrum time sequence with the gyrosynchrotron source function with five to six free parameters. At the stage when the contribution from the acceleration region dominates the radio spectrum, the X-ray- and radio-derived electron energy spectral indices agree well with each other. During this time the maximum energy of the accelerated electron spectrum displays a monotonic increase with time from {approx}300 keV to {approx}2 MeV over roughly one minute duration indicative of an acceleration process in the form of growth of the power-law tail; the fast electron residence time in the acceleration region is about 2-4 s, which is much longer than the time of flight and so requires a strong diffusion mode there to inhibit free-streaming propagation. The acceleration region has a relatively strong magnetic field, B {approx} 120 G, and a low thermal density, n{sub e} {approx}< 2 Multiplication-Sign 10{sup 9} cm{sup -3}. These acceleration region properties are consistent with a stochastic acceleration mechanism.

Fleishman, Gregory D.; Nita, Gelu M.; Gary, Dale E. [Center for Solar-Terrestrial Research, New Jersey Institute of Technology, Newark, NJ 07102 (United States); Kontar, Eduard P. [Department of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ (United Kingdom)

2013-05-10T23:59:59.000Z

373

Infrared absorption spectroscopy and chemical kinetics of free radicals  

SciTech Connect (OSTI)

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

374

X-Ray Interactions with Matter from the Center for X-Ray Optics (CXRO)  

DOE Data Explorer [Office of Scientific and Technical Information (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.

375

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

376

Analysis of the near-edge X-ray-absorption fine-structure of anthracene: A combined theoretical and experimental study  

SciTech Connect (OSTI)

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

377

Opacity of iron, nickel, and copper plasmas in the x-ray wavelength range: Theoretical interpretation of 2p-3d absorption spectra  

SciTech Connect (OSTI)

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

378

Reverse engineering the ancient ceramic technology based on X-ray fluorescence spectromicroscopy  

SciTech Connect (OSTI)

We present results of X-ray fluorescence (XRF) microprobe analyses of ancient ceramic cross-sections aiming at deciphering the different firing protocols used for their production. Micro-focused XRF elemental mapping, Fe chemical mapping and Fe K-edge X-ray absorption near edge structure spectroscopy were performed on pre-sigillata ceramics from southern Gaul, and terra Sigillata vessels from Italy and southern Gaul. Pieces from the different workshops and regions showed significant difference in the starting clay material, clay conditioning and kiln firing condition. By contrast, sherds from the same workshop exhibited more subtle differences and possible misfirings. Understanding the precise firing conditions and protocols would allow recreation of kilns for various productions. Furthermore, evolution and modification of kiln design would shed some light on how ancient potters devised solutions to diverse technological problems they encountered.

Sciau, Philippe; Leon, Yoanna; Goudeau, Philippe; Fakra, Sirine C.; Webb, Sam; Mehta, Apurva

2011-07-06T23:59:59.000Z

379

MICROANALYSIS OF NY/NJ HARBOR SEDIMENTS USING SYNCHROTRON X-RAY BEAMS.  

SciTech Connect (OSTI)

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

380

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

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

The XMM-Newton Survey in the Marano Field I. The X-ray data and optical follow-up  

E-Print Network [OSTI]

We report on a medium deep XMM-Newton survey of the Marano Field and optical follow-up observations. The mosaicked XMM-Newton pointings in this optical quasar survey field cover 0.6 square degree with a total of 120 ksec good observation time. We detected 328 X-ray sources in total. The turnover flux of our sample is f~5x10^(-15) erg/cm^2/s in the 0.2-10 keV band. With VLT FORS1 and FORS2 spectroscopy we classified 96 new X-ray counterparts. The central 0.28 square degree, where detailed optical follow-up observations were performed, contain 170 X-ray sources (detection likelihood ML>10), out of which 48 had already been detected by ROSAT. In this region we recover 23 out of 29 optically selected quasars. With a total of 110 classifications in our core sample we reach a completeness of ~65%. About one third of the XMM-Newton sources is classified as type II AGN with redshifts mostly below 1.0. Furthermore, we detect five high redshift type II AGN (2.2X-ray colors of the core sample indicate that most of the still unidentified X-ray sources are likely to be type II AGN. We calculate absorbing column densities and show that the ratio of absorbed to unabsorbed objects is significantly higher for type II AGN than for type I AGN. Nevertheless, we find a few unabsorbed type II AGN. The X-ray hardness ratios of some high redshift type I AGN also give an indication of heavy absorption. However, none of these type I objects is bright enough for spectral extraction and detailed model fitting. Furthermore, we classified three X-ray bright optically normal galaxies (XBONGs) as counterparts. They show properties similar to type II AGN, probably harbouring an active nucleus.

M. Krumpe; G. Lamer; A. D. Schwope; S. Wagner; G. Zamorani; M. Mignoli; R. Staubert; L. Wisotzki; G. Hasinger

2006-12-14T23:59:59.000Z

382

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 (OSTI)

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

383

Chemical order in Ge{sub x}As{sub y}Se{sub 1-x-y} glasses probed by high resolution X-ray photoelectron spectroscopy  

SciTech Connect (OSTI)

We have measured high-resolution x-ray photoelectron spectra of Ge{sub x}As{sub y}Se{sub 1-x-y} glasses with a mean coordination number (MCN) from 2.2 to 2.78. The valence band spectra showed that a number of Se–Se–Se trimers can be found in Se-rich samples, whilst multiband features induced by phase separation can be observed in extremely Se-poor samples. When the Ge, As, and Se 3d spectra were decomposed into several doublets, which correspond, respectively, to different chemical environments, the perfect AsSe{sub 3/2} pyramidal and GeSe{sub 4/2} tetrahedral structures in Se-rich samples gradually evolved into defect structures, including As–As and Ge–Ge homopolar bonds, with increasing Ge and As concentrations. Two transition-like features were found at MCN?=?2.5 and 2.64–2.72 that correspond first to the disappearance of Se-chains in the glass network and, subsequently, destruction of the perfect GeSe{sub 4/2} tetrahedral structures, respectively.

Xu, S. W. [Laser Physics Centre, Research School of Physics and Engineering, Australian National University, Canberra, ACT 0200 (Australia); College of Applied Sciences, Beijing University of Technology, Beijing100124 (China); Wang, R. P.; Luther-Davies, B. [Laser Physics Centre, Research School of Physics and Engineering, Australian National University, Canberra, ACT 0200 (Australia); Kovalskiy, A. [Department of Physics and Astronomy, Austin Peay State University, Clarksville, Tennessee 37043 (United States); Miller, A. C.; Jain, H. [Department of Materials Science and Engineering, Lehigh University, 5 East Packer Avenue, Bethlehem, Pennsylvania 18015-3195 (United States)

2014-02-28T23:59:59.000Z

384

Lensless X-Ray Imaging in Reflection  

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

385

Two-dimensional x-ray correlation spectroscopy of remote core states Daniel Healion, Yu Zhang, Jason D. Biggs, Weijie Hua, and Shaul Mukamel  

E-Print Network [OSTI]

, Jason D. Biggs, Weijie Hua, and Shaul Mukamel Citation: Structural Dynamics 1, 014101 (2014); doi: 10-ray correlation spectroscopy of remote core states Daniel Healion, Yu Zhang, Jason D. Biggs, Weijie Hua, and Shaul

Mukamel, Shaul

386

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.

387

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

388

Cryogenic, high-resolution x-ray detector with high count rate capability  

DOE Patents [OSTI]

A cryogenic, high-resolution X-ray detector with high count rate capability has been invented. The new X-ray detector is based on superconducting tunnel junctions (STJs), and operates without thermal stabilization at or below 500 mK. The X-ray detector exhibits good resolution (.about.5-20 eV FWHM) for soft X-rays in the keV region, and is capable of counting at count rates of more than 20,000 counts per second (cps). Simple, FET-based charge amplifiers, current amplifiers, or conventional spectroscopy shaping amplifiers can provide the electronic readout of this X-ray detector.

Frank, Matthias (Oakland, CA); Mears, Carl A. (Windsor, CA); Labov, Simon E. (Berkeley, CA); Hiller, Larry J. (Livermore, CA); Barfknecht, Andrew T. (Menlo Park, CA)

2003-03-04T23:59:59.000Z

389

Linear accelerator x-ray sources with high duty cycle  

SciTech Connect (OSTI)

X-ray cargo inspection systems typically use a several-MV pulsed linear accelerator (linac) to produce a bremsstrahlung spectrum of x rays by bombarding a target with electrons. The x rays traverse the cargo and are detected by a detector array. Spectroscopy of the detected x rays is very desirable: if one can determine the spectrum of the transmitted x rays, one can determine the Z of the material they traversed. Even in relatively low-dose modes of operation, thousands of x rays arrive at each detector element during each pulse, unless the x rays are heavily absorbed or scattered by the cargo. For portal or fixed-site systems, dose rates, and therefore x-ray count rates, are even higher. Because of the high x-ray count rate, spectroscopy is impractical in conventional cargo inspection systems, except in certain special cases. For a mobile system, typical pulse durations are a few microseconds, and the number of pulses is on the order of 100 per second, leading to a duty factor of about 0.04%. Clearly, a linear accelerator x-ray source with much higher duty factor would be useful, since then the same number of x rays could be spread out over time, reducing the x-ray count rate. In this paper, we explore the possibility of designing a linear accelerator system, using more or less Conventional Off the Shelf (COTS) components, capable of duty cycles of 1% or greater. A survey was conducted of available linac RF source options and, given the possibilities, calculations were performed for suitable beam centerline designs. Keeping in mind that the size and cost of the accelerator system should be practical for use in a mobile cargo inspection system, only a few options are shown to be reasonably feasible, both requiring the use of klystrons instead of the magnetrons used in conventional systems. An S-Band design appears clearly possible, and there is also a promising X-Band design.

Condron, Cathie; Brown, Craig; Gozani, Tsahi; Langeveld, Willem G. J. [Rapiscan Laboratories, Inc., 520 Almanor Ave. Sunnyvale, CA 94085 (United States); Hernandez, Michael [XScell corp., 2134 Old Middlefield Way, Mountain View, CA 94043 (United States)

2013-04-19T23:59:59.000Z

390

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

391

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

392

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

393

National Ignition Facility core x-ray streak camera  

SciTech Connect (OSTI)

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

394

Synchrotron-Radiation Induced X-Ray Emission (SRIXE)  

SciTech Connect (OSTI)

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

395

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

396

Optical re-injection in cavity-enhanced absorption spectroscopy  

SciTech Connect (OSTI)

Non-mode-matched cavity-enhanced absorption spectrometry (e.g., cavity ringdown spectroscopy and integrated cavity output spectroscopy) is commonly used for the ultrasensitive detection of trace gases. These techniques are attractive for their simplicity and robustness, but their performance may be limited by the reflection of light from the front mirror and the resulting low optical transmission. Although this low transmitted power can sometimes be overcome with higher power lasers and lower noise detectors (e.g., in the near-infrared), many regimes exist where the available light intensity or photodetector sensitivity limits instrument performance (e.g., in the mid-infrared). In this article, we describe a method of repeatedly re-injecting light reflected off the front mirror of the optical cavity to boost the cavity's circulating power and deliver more light to the photodetector and thus increase the signal-to-noise ratio of the absorption measurement. We model and experimentally demonstrate the method's performance using off-axis cavity ringdown spectroscopy (OA-CRDS) with a broadly tunable external cavity quantum cascade laser. The power coupled through the cavity to the detector is increased by a factor of 22.5. The cavity loss is measured with a precision of 2 × 10{sup ?10} cm{sup ?1}/?(Hz;) an increase of 12 times over the standard off-axis configuration without reinjection and comparable to the best reported sensitivities in the mid-infrared. Finally, the re-injected CRDS system is used to measure the spectrum of several volatile organic compounds, demonstrating the improved ability to resolve weakly absorbing spectroscopic features.

Leen, J. Brian, E-mail: b.leen@lgrinc.com; O’Keefe, Anthony [Los Gatos Research, 67 E. Evelyn Avenue, Suite 3, Mountain View, California 94041 (United States)

2014-09-15T23:59:59.000Z

397

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

398

E-Print Network 3.0 - absorption line spectroscopy Sample Search...  

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

University Collection: Physics 88 Terahertz Time-Domain Spectroscopy Study of Silica Aerogels and Adsorbed Molecular Jiangquan Zhang and D. Grischkowsky* Summary: absorption...

399

E-Print Network 3.0 - absorption spectroscopy aas Sample Search...  

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

Sciences and Ecology 18 Terahertz Time-Domain Spectroscopy Study of Silica Aerogels and Adsorbed Molecular Jiangquan Zhang and D. Grischkowsky* Summary: absorption...

400

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

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

Collection: Mathematics 79 Terahertz Time-Domain Spectroscopy Study of Silica Aerogels and Adsorbed Molecular Jiangquan Zhang and D. Grischkowsky* Summary: absorption...

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

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

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

> >> Page: << < 1 2 3 4 5 > >> 41 Terahertz Time-Domain Spectroscopy Study of Silica Aerogels and Adsorbed Molecular Jiangquan Zhang and D. Grischkowsky* Summary: absorption...

402

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

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

gas analysis Alexander Fateev, Snnik Clausen Summary: applications and in particular in atomicmolecular absorption spectroscopy, the transition moment is replaced... +CO+CO2)....

403

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

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

gas analysis Alexander Fateev, Snnik Clausen Summary: applications and in particular in atomicmolecular absorption spectroscopy, the transition moment is replaced... +CO+CO2)....

404

E-Print Network 3.0 - absorption gamma-ray spectroscopy Sample...  

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

405

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

406

Quantum Limits and Robustness of Nonlinear Intracavity Absorption Spectroscopy  

E-Print Network [OSTI]

We investigate the limits of intracavity absorption spectroscopy with nonlinear media. Using a common theoretical framework, we compare the detection of a trace gas within an undriven cavity with gain near and above threshold, a driven cavity with gain kept just below threshold, and a cavity driven close to the saturation point of a saturable absorber. These phase-transition-based metrology methods are typically quantum-limited by spontaneous emission, and we compare them to the empty cavity shotnoise-limited case. Although the fundamental limits achievable with nonlinear media do not surpass the empty cavity limits, we show that nonlinear methods are more robust against certain technical noise models. This recognition may have applications in spectrometer design for devices operating in non-ideal field environments.

John K. Stockton; Ari K. Tuchman

2008-10-23T23:59:59.000Z

407

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 (OSTI)

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

408

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 (OSTI)

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

409

Resource Letter on Stimulated Inelastic X-ray Scattering at an XFEL  

SciTech Connect (OSTI)

At sufficient X-ray intensity, stimulated effects in inelastic scattering will become important. These coherent, non-linear optical phenomena may be used to impulsively produce a high degree of collective excitation in, for example, correlated electron materials, suitable for performing ultrafast time-resolved spectroscopy. This Resource Letter collects information on fundamental aspects of stimulated X-ray scattering and evaluates the prospect for successful experiments at a present or future X-ray free electron laser (XFEL) facility.

Patterson, Bruce

2010-09-02T23:59:59.000Z

410

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

411

A high pressure cell for supercritical CO{sub 2} on-line chemical reactions studied with x-ray techniques  

SciTech Connect (OSTI)

A versatile high pressure X-ray sample cell has been developed for conducting in situ time-resolved X-ray scattering experiments in the pressure and temperature regime required (pressures up to 210 bars and temperatures up to 120 °C) for chemical reactions in supercritical fluids. The large exit opening angle of the cell allows simultaneous performance of SAXS-WAXS experiments. Diamond windows are used in order to benefit from the combination of maximum strength, minimal X-ray absorption and chemical inertia. The sample cell can also be utilised for X-ray spectroscopy experiments over a wide range of photon energies. Results of the online synthesis of a block copolymer, poly(methyl methacrylate-block-poly(benzyl methacrylate), by Reversible Addition-Fragmentation Chain Transfer (RAFT) in a supercritical CO{sub 2} dispersion polymerisation will be discussed. The contribution of the density fluctuations, as function of temperature, to the X-ray scattering signal has been quantified in order to allow appropriate background subtractions.

Hermida-Merino, Daniel; Portale, Giuseppe; Bras, Wim, E-mail: Wim.Bras@esrf.eu, E-mail: Steve.Howdle@nottingham.ac.uk [DUBBLE@ESRF, Netherlands Organisation for Scientific Research (N.W.O.), CS40220, 38043, Grenoble, Cedex 9 (France); Fields, Peter; Wilson, Richard; Bassett, Simon P.; Jennings, James; Dellar, Martin; Howdle, Steven M., E-mail: Wim.Bras@esrf.eu, E-mail: Steve.Howdle@nottingham.ac.uk [School of Chemistry, University of Nottingham, University Park, Nottingham NG7 2RD (United Kingdom); Gommes, Cedric [Department of Chemical Engineering, University of Liège B6A, allée du 6 Août 3, B-4000 Liège (Belgium); Vrolijk, Benno C. M. [Element Six BV, P.O. Box 119, 5430 AC Cuijk (Netherlands)

2014-09-15T23:59:59.000Z

412

Probing bismuth ferrite nanoparticles by hard x-ray photoemission: Anomalous occurrence of metallic bismuth  

SciTech Connect (OSTI)

We have investigated bismuth ferrite nanoparticles (?75?nm and ?155?nm) synthesized by a chemical method, using soft X-ray (1253.6?eV) and hard X-ray (3500, 5500, and 7500?eV) photoelectron spectroscopy. This provided an evidence for the variation of chemical state of bismuth in crystalline, phase pure nanoparticles. X-ray photoelectron spectroscopy analysis using Mg K? (1253.6?eV) source showed that iron and bismuth were present in both Fe{sup 3+} and Bi{sup 3+} valence states as expected for bismuth ferrite. However, hard X-ray photoelectron spectroscopy analysis of the bismuth ferrite nanoparticles using variable photon energies unexpectedly showed the presence of Bi{sup 0} valence state below the surface region, indicating that bismuth ferrite nanoparticles are chemically inhomogeneous in the radial direction. Consistently, small-angle X-ray scattering reveals a core-shell structure for these radial inhomogeneous nanoparticles.

Chaturvedi, Smita; Rajendra, Ranguwar; Ballav, Nirmalya; Kulkarni, Sulabha, E-mail: s.kulkarni@iiserpune.ac.in [Indian Institute of Science Education and Research, Dr. Homi Bhabha Road, Pune 411008 (India); Sarkar, Indranil [DESY Photon Science, Deutsches Elektronen-Synchrotron, 22607 Hamburg (Germany); Shirolkar, Mandar M. [Hefei National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei, Anhui 230026 (China); Jeng, U-Ser; Yeh, Yi-Qi [National Synchrotron Radiation Research Center, 101, Hsin-Ann Road, Science Park, Hsinchu 3007-6, Taiwan (China)

2014-09-08T23:59:59.000Z

413

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.

414

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.

415

X-ray pump optical probe cross-correlation study of GaAs  

SciTech Connect (OSTI)

Ultrafast dynamics in atomic, molecular and condensed-matter systems are increasingly being studied using optical-pump, X-ray probe techniques where subpicosecond laser pulses excite the system and X-rays detect changes in absorption spectra and local atomic structure. New opportunities are appearing as a result of improved synchrotron capabilities and the advent of X-ray free-electron lasers. These source improvements also allow for the reverse measurement: X-ray pump followed by optical probe. We describe here how an X-ray pump beam transforms a thin GaAs specimen from a strong absorber into a nearly transparent window in less than 100 ps, for laser photon energies just above the bandgap. We find the opposite effect - X-ray induced optical opacity - for photon energies just below the bandgap. This raises interesting questions about the ultrafast many-body response of semiconductors to X-ray absorption, and provides a new approach for an X-ray/optical cross-correlator for synchrotron and X-ray free-electron laser applications.

Durbin, S.M.; Clevenger, T.; Graber, T.; Henning, R. (Purdue); (UC)

2012-09-10T23:59:59.000Z

416

Microgap x-ray detector  

DOE Patents [OSTI]

An x-ray detector is disclosed which provides for the conversion of x-ray photons into photoelectrons and subsequent amplification of these photoelectrons through the generation of electron avalanches in a thin gas-filled region subject to a high electric potential. The detector comprises a cathode (photocathode) and an anode separated by the thin, gas-filled region. The cathode may comprise a substrate, such a beryllium, coated with a layer of high atomic number material, such as gold, while the anode can be a single conducting plane of material, such as gold, or a plane of resistive material, such as chromium/silicon monoxide, or multiple areas of conductive or resistive material, mounted on a substrate composed of glass, plastic or ceramic. The charge collected from each electron avalanche by the anode is passed through processing electronics to a point of use, such as an oscilloscope. 3 figures.

Wuest, C.R.; Bionta, R.M.; Ables, E.

1994-05-03T23:59:59.000Z

417

Microgap x-ray detector  

DOE Patents [OSTI]

An x-ray detector which provides for the conversion of x-ray photons into photoelectrons and subsequent amplification of these photoelectrons through the generation of electron avalanches in a thin gas-filled region subject to a high electric potential. The detector comprises a cathode (photocathode) and an anode separated by the thin, gas-filled region. The cathode may comprise a substrate, such a beryllium, coated with a layer of high atomic number material, such as gold, while the anode can be a single conducting plane of material, such as gold, or a plane of resistive material, such as chromium/silicon monoxide, or multiple areas of conductive or resistive material, mounted on a substrate composed of glass, plastic or ceramic. The charge collected from each electron avalanche by the anode is passed through processing electronics to a point of use, such as an oscilloscope.

Wuest, Craig R. (Danville, CA); Bionta, Richard M. (Livermore, CA); Ables, Elden (Livermore, CA)

1994-01-01T23:59:59.000Z

418

Spectral analysis of X-ray binaries  

E-Print Network [OSTI]

In this thesis, I present work from three separate research projects associated with observations of X-ray binaries. Two of those revolve around spectral characteristics of neutron star low-mass X-ray binaries (NS-LMXBs), ...

Fridriksson, Joel Karl

2011-01-01T23:59:59.000Z

419

Lensless X-Ray Imaging in Reflection  

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

X-Ray Imaging in Reflection Print The advent of x-ray free-electron laser (XFEL) light sources has led to an outburst of research activities in the field of lensless imaging. XFELs...

420

Lensless X-Ray Imaging in Reflection  

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

X-Ray Imaging in Reflection Print Wednesday, 26 October 2011 00:00 The advent of x-ray free-electron laser (XFEL) light sources has led to an outburst of research activities...

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

Producing X-rays at the APS  

ScienceCinema (OSTI)

An introduction and overview of the Advanced Photon Source at Argonne National Laboratory, the technology that produces the brightest X-ray beams in the Western Hemisphere, and the research carried out by scientists using those X-rays.

None

2013-04-19T23:59:59.000Z

422

Eta Car and Its Surroundings: the X-ray Diagnosis  

E-Print Network [OSTI]

X-ray emission from the supermassive star Eta Carinae (\\ec) originates from hot shocked gas produced by current stellar mass loss as well as ejecta from prior eruptive events. Absorption of this emission by cool material allows the determination of the spatial and temporal distribution of this material. Emission from the shocked gas can provide important information about abundances through the study of thermal X-ray line emission. We discuss how studies of the X-ray emission from Eta Car at a variety of temporal, spatial and spectral scales and resolutions have helped refine our knowledge of both the continuous and discrete mass loss from the system, and its interactions with more extended material around the star.

M. F. Corcoran; K. Hamaguchi

2007-03-02T23:59:59.000Z

423

Phase-sensitive X-ray imager  

DOE Patents [OSTI]

X-ray phase sensitive wave-front sensor techniques are detailed that are capable of measuring the entire two-dimensional x-ray electric field, both the amplitude and phase, with a single measurement. These Hartmann sensing and 2-D Shear interferometry wave-front sensors do not require a temporally coherent source and are therefore compatible with x-ray tubes and also with laser-produced or x-pinch x-ray sources.

Baker, Kevin Louis

2013-01-08T23:59:59.000Z

424

Theory of angular dispersive imaging hard x-ray spectrographs  

E-Print Network [OSTI]

A spectrograph is an optical instrument that disperses photons of different energies into distinct directions and space locations, and images photon spectra on a position-sensitive detector. Spectrographs consist of collimating, angular dispersive, and focusing optical elements. Bragg reflecting crystals arranged in an asymmetric scattering geometry are used as the dispersing elements. A ray-transfer matrix technique is applied to propagate x-rays through the optical elements. Several optical designs of hard x-ray spectrographs are proposed and their performance is analyzed. Spectrographs with an energy resolution of 0.1 meV and a spectral window of imaging up to a few tens of meVs are shown to be feasible for inelastic x-ray scattering (IXS) spectroscopy applications. In another example, a spectrograph with a 1-meV spectral resolution and 85-meV spectral window of imaging is considered for Cu K-edge resonant IXS (RIXS).

Shvyd'ko, Yuri

2015-01-01T23:59:59.000Z

425

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

SciTech Connect (OSTI)

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

Silvain, J.F.; Fouassier, O.; Lescaux, S. [Institut de Chimie de la Matiere Condensee de Bordeaux (ICMCB) - CNRS, Universite de Bordeaux 1, 87 Avenue du Dr A. Schweitzer, F-33608 PESSAC (France); Veeco, Z.I. de la Gaudree, 11 Rue Marie Poussepin, F-91412 Dourdain (France)

2004-11-01T23:59:59.000Z

426

Deduction of the chemical state and the electronic structure of Nd{sub 2}Fe{sub 14}B compound from X-ray photoelectron spectroscopy core-level and valence-band spectra  

SciTech Connect (OSTI)

Characterization of chemical state and electronic structure of the technologically important Nd{sub 2}Fe{sub 14}B compound is attractive for understanding the physical nature of its excellent magnetic properties. X-ray photoelectron spectroscopy (XPS) study of such rare-earth compound is important and also challenging due to the easy oxidation of surface and small photoelectron cross-sections of rare-earth 4f electrons and B 2p electrons, etc. Here, we reported an investigation based on XPS spectra of Nd{sub 2}Fe{sub 14}B compound as a function of Ar ion sputtering time. The chemical state of Fe and that of B in Nd{sub 2}Fe{sub 14}B compound can be clearly determined to be 0 and ?3, respectively. The Nd in Nd{sub 2}Fe{sub 14}B compound is found to have the chemical state of close to +3 instead of +3 as compared with the Nd in Nd{sub 2}O{sub 3}. In addition, by comparing the valence-band spectrum of Nd{sub 2}Fe{sub 14}B compound to that of the pure Fe, the contributions from Nd, Fe, and B to the valence-band structure of Nd{sub 2}Fe{sub 14}B compound is made more clear. The B 2p states and B 2s states are identified to be at ?11.2 eV and ?24.6 eV, respectively, which is reported for the first time. The contribution from Nd 4f states can be identified both in XPS core-level spectrum and XPS valence-band spectrum. Although Nd 4f states partially hybridize with Fe 3d states, Nd 4f states are mainly localized in Nd{sub 2}Fe{sub 14}B compound.

Wang, Jing; Liang, Le [School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Zhang, Lanting, E-mail: lantingzh@sjtu.edu.cn, E-mail: lmsun@sjtu.edu.cn [School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Hirano Institute for Materials Innovation, Shanghai Jiao Tong University, Shanghai 200240 (China); Sun, Limin, E-mail: lantingzh@sjtu.edu.cn, E-mail: lmsun@sjtu.edu.cn [Instrumental Analysis Center, Shanghai Jiao Tong University, Shanghai 200240 (China); Hirano, Shinichi [Hirano Institute for Materials Innovation, Shanghai Jiao Tong University, Shanghai 200240 (China)

2014-10-28T23:59:59.000Z

427

Chandra X-ray Observatory Center  

E-Print Network [OSTI]

Chandra X-ray Observatory Center Harvard-Smithsonian Center for Astrophysics 60 Garden St in hot gas about 250 million light years from Earth. (Credit: X-ray: NASA/CXC/SAO/E.Bulbul, et al-Newton has revealed a mysterious X-ray signal in the data. This signal is represented in the circled data

428

Chandra X-ray Observatory Center  

E-Print Network [OSTI]

Chandra X-ray Observatory Center Harvard-Smithsonian Center for Astrophysics 60 Garden St million light years from Earth. (Credit: X-ray: NASA/CXC/Wesleyan Univ./R.Kilgard, et al; Optical: NASA with optical data from the Hubble Space Telescope (red, green, and blue). The X-ray data reveal hundreds

429

Cryotomography x-ray microscopy state  

DOE Patents [OSTI]

An x-ray microscope stage enables alignment of a sample about a rotation axis to enable three dimensional tomographic imaging of the sample using an x-ray microscope. A heat exchanger assembly provides cooled gas to a sample during x-ray microscopic imaging.

Le Gros, Mark (Berkeley, CA); Larabell, Carolyn A. (Berkeley, CA)

2010-10-26T23:59:59.000Z

430

Chandra X-ray Observatory Center  

E-Print Network [OSTI]

Chandra X-ray Observatory Center Harvard-Smithsonian Center for Astrophysics 60 Garden St 200 million light years from Earth. (Credit: X-ray: NASA/CXC/UAH/M.Sun et al; Optical: NASA, ESA, & the Hubble Heritage Team (STScI/AURA) Caption: This composite image from the Chandra X-ray Observatory (blue

431

Chandra X-ray Observatory Center  

E-Print Network [OSTI]

Chandra X-ray Observatory Center Harvard-Smithsonian Center for Astrophysics 60 Garden St. Cambridge, MA 02138 USA http://chandra.harvard.edu Four Supernova Remnants: NASA's Chandra X-ray Observatory's Chandra X-ray Observatory, four newly processed images of supernova remnants dramatically illustrate

432

Spatial resolution of synchrotron x-ray microtomography in high energy range: Effect of x-ray energy and sample-to-detector distance  

SciTech Connect (OSTI)

Spatial resolution of three-dimensional images obtained by synchrotron X-ray microtomography technique is evaluated using cyclic bar patterns machined on a steel wire. Influences of X-ray energy and the sample-to-detector distance on spatial resolution were investigated. High X-ray energies of 33-78 keV are applied due to the high X-ray absorption of transition metals. Best spatial resolution of about 1.2 {mu}m pitch was observed at the sample-to-detector distance range of 20-110 mm and at the energy range of 68-78 keV. Several factors such as X-ray scattering and diffraction phenomena affecting the degradation of spatial resolution are also discussed.

Seo, D.; Tomizato, F.; Toda, H.; Kobayashi, M. [Department of Mechanical Engineering, Toyohashi University of Technology, Toyohashi, Aichi 441-8580 (Japan); Uesugi, K.; Takeuchi, A.; Suzuki, Y. [Japan Synchrotron Radiation Research Institute, Mikazuki, Sayo, Hyogo 679-5198 (Japan)

2012-12-24T23:59:59.000Z

433

X-ray Properties of Young Stellar Objects in OMC-2 and OMC-3 from the Chandra X-ray Observatory  

E-Print Network [OSTI]

We report X-ray results of the Chandra observation of Orion Molecular Cloud 2 and 3. A deep exposure of \\sim 100 ksec detects \\sim 400 X-ray sources in the field of view of the ACIS array, providing one of the largest X-ray catalogs in a star forming region. Coherent studies of the source detection, time variability, and energy spectra are performed. We classify the X-ray sources into class I, class II, and class III+MS based on the J, H, and K-band colors of their near infrared counterparts and discuss the X-ray properties (temperature, absorption, and time variability) along these evolutionary phases.

M. Tsujimoto; K. Koyama; Y. Tsuboi; M. Goto; N. Kobayashi

2001-10-12T23:59:59.000Z

434

SMB, X-Ray Spectroscopy & Imaging  

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

AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr May JunDatastreamsmmcrcalgovInstrumentsrucLas ConchasPassive Solar HomePromisingStoriesSANDIA REPORT SANDSDNTM7/31/13SLACM J-M-1SMB SMBHome

435

Extending The Methodology Of X-ray Crystallography To Allow X-ray  

E-Print Network [OSTI]

, the radiation damage. While the radiation damage problem can be mitigated somewhat by using cryogenic techniques resolution without serious radiation damage to the specimens. Although X-ray crystallography becomesExtending The Methodology Of X-ray Crystallography To Allow X-ray Microscopy Without X-ray Optics

Miao, Jianwei "John"

436

X-ray Pulsations in the Supersoft X-ray Binary CAL 83  

E-Print Network [OSTI]

X-ray data reveal that the supersoft X-ray binary CAL 83 exhibits 38.4 minute pulsations at some epochs. These X-ray variations are similar to those found in some novae and are likely to be caused by nonradial pulsations the white dwarf. This is the first detection of pulsations in a classical supersoft X-ray binary.

P. C. Schmidtke; A. P. Cowley

2005-09-28T23:59:59.000Z

437

X-ray transmissive debris shield  

DOE Patents [OSTI]

An X-ray debris shield for use in X-ray lithography that is comprised of an X-ray window having a layer of low density foam exhibits increased longevity without a substantial increase in exposure time. The low density foam layer serves to absorb the debris emitted from the X-ray source and attenuate the shock to the window so as to reduce the chance of breakage. Because the foam is low density, the X-rays are hardly attenuated by the foam and thus the exposure time is not substantially increased.

Spielman, Rick B. (Albuquerque, NM)

1996-01-01T23:59:59.000Z

438

Synchronization of x-ray pulses to the pump laser in an ultrafast x-ray facility  

E-Print Network [OSTI]

Accurate timing of ultrafast x-ray probe pulses emitted fromOF X-RAY PULSES TO THE PUMP LASER IN AN ULTRAFAST X-RAY

Corlett, J.N.; Barry, W.; Byrd, J.M.; Schoenlein, R.; Zholents, A.

2002-01-01T23:59:59.000Z

439

X-ray lithography using holographic images  

DOE Patents [OSTI]

A non-contact X-ray projection lithography method for producing a desired X-ray image on a selected surface of an X-ray-sensitive material, such as photoresist material on a wafer, the desired X-ray image having image minimum linewidths as small as 0.063 .mu.m, or even smaller. A hologram and its position are determined that will produce the desired image on the selected surface when the hologram is irradiated with X-rays from a suitably monochromatic X-ray source of a selected wavelength .lambda.. On-axis X-ray transmission through, or off-axis X-ray reflection from, a hologram may be used here, with very different requirements for monochromaticity, flux and brightness of the X-ray source. For reasonable penetration of photoresist materials by X-rays produced by the X-ray source, the wavelength X, is preferably chosen to be no more than 13.5 nm in one embodiment and more preferably is chosen in the range 1-5 nm in the other embodiment. A lower limit on linewidth is set by the linewidth of available microstructure writing devices, such as an electron beam.

Howells, Malcolm R. (Berkeley, CA); Jacobsen, Chris (Sound Beach, NY)

1995-01-01T23:59:59.000Z

440

Evidence Against BALS in the X-ray Bright QSO PG1416-129  

E-Print Network [OSTI]

Recent results from the ROSAT All Sky Survey, and from deep ROSAT pointings reveal that broad absorption line quasars (BALQSOs) are weak in the soft X-ray bandpass (with optical-to-X-ray spectral slope alpha_{ox}>1.8) in comparison to QSOs with normal OUV spectra (mean alpha_{ox}=1.4). One glaring exception appeared to be the nearby BALQSO PG1416-129, which is a bright ROSAT source showing no evidence for intrinsic soft X-ray absorption. We present here our new HST FOS spectrum of PG1416-129, in which we find no evidence for BALs. We show that the features resulting in the original BAL classification, based on IUE spectra, were probably spurious. On the basis of UV, X-ray and optical evidence, we conclude that PG1416-129, is not now, and has never been a BALQSO. Our result suggests that weak soft X-ray emission is a defining characteristic of true BALQSOs. If BALQSOs indeed harbor normal intrinsic spectral energy distributions, their observed soft X-ray weakness is most likely the result of absorption. The ubiquitous occurrence of weak soft X-ray emission with UV absorption (BALs) thus suggests absorbers in each energy regime that are physically associated, if not identical.

Paul J. Green; Thomas L. Aldcroft; Smita Mathur; Norbert Schartel

1997-02-24T23:59:59.000Z

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

Imaging of lateral spin valves with soft x-ray microscopy  

SciTech Connect (OSTI)

We investigated Co/Cu lateral spin valves by means of high-resolution transmission soft x-ray microscopy with magnetic contrast that utilizes x-ray magnetic circular dichroism (XMCD). No magnetic XMCD contrast was observed at the Cu L{sub 3} absorption edge, which should directly image the spin accumulation in Cu. Although electrical transport measurements in a non-local geometry clearly detected the spin accumulation in Cu, which remained unchanged during illumination with circular polarized x-rays at the Co and Cu L{sub 3} absorption edges.

Mosendz, O.; Mihajlovic, G.; Pearson, J. E.; Fischer, P.; Im, M.-Y.; Bader, S. D.; Hoffmann, A.

2009-05-01T23:59:59.000Z

442

Imaging of lateral spin valves with soft x-ray microscopy.  

SciTech Connect (OSTI)

We investigated Co/Cu lateral spin valves by means of high-resolution transmission soft x-ray microscopy with magnetic contrast that utilizes x-ray magnetic circular dichroism (XMCD). No magnetic XMCD contrast was observed at the Cu L{sub 3} absorption edge, which should directly image the spin accumulation in Cu, although electrical transport measurements in a nonlocal geometry clearly detected the spin accumulation in Cu, which remained unchanged during illumination with circular polarized x rays at the Co and Cu L{sub 3} absorption edges.

Mosendz, O.; Mihajlovic, G.; Pearson, J. E.; Fischer, P.; Im, M.-Y.; Bader, S. D.; Hoffmann, A.; LBNL

2009-01-01T23:59:59.000Z

443

SciTech Connect: Validations of Time-Resolved X-Ray Emissions...  

Office of Scientific and Technical Information (OSTI)

Validations of Time-Resolved X-Ray Emissions Spectroscopy for Analysis of Mn-Based Natural and Artifical Sunlight-to-Energy Assemblies Citation Details In-Document Search Title:...

444

Characterisation of organic photovoltaics by synchrotron soft X-ray techniques.  

E-Print Network [OSTI]

??Research Doctorate - Doctor of Philosophy (PhD) The use of advanced synchrotron X-ray spectroscopy and microspectroscopy techniques can probe the nanoscale structure of organic solar… (more)

Burke, Kerry B.

2011-01-01T23:59:59.000Z

445

X-ray Imaging Workshop  

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

AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr MayAtmosphericNuclear SecurityTensile Strain Switched FerromagnetismWaste and MaterialsWenjun1of EnergyX-ray Computed TomographyImaging

446

X-ray fluorescence mapping  

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

AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr MayAtmosphericNuclear SecurityTensile Strain Switched FerromagnetismWaste and MaterialsWenjun1of EnergyX-rayNew Materialsray

447

X-Ray Science Education  

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

AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr May JunDatastreamsmmcrcalgovInstrumentsrucLasDelivered energy consumption byAbout SRNL Home SRNL main campusMore thanX-Ray Imagingfeed

448

Borman effect in resonant diffraction of X-rays  

SciTech Connect (OSTI)

A dynamic theory of resonant diffraction (occurring when the energy of incident radiation is close to the energy of the absorption edge of an element in the composition of a given substance) of synchronous X-rays is developed in the two-wave approximation in the coplanar Laue geometry for large grazing angles in perfect crystals. A sharp decrease in the absorption coefficient in the substance with simultaneously satisfied diffraction conditions (Borman effect) is demonstrated, and the theoretical and first experimental results are compared. The calculations reveal the possibility of applying this approach in analyzing the quadrupole-quadrupole contribution to the absorption coefficient.

Oreshko, A. P., E-mail: ap.oreshko@physics.msu.ru [Moscow State University (Russian Federation)

2013-08-15T23:59:59.000Z

449

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

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

absorptions were found ranging from... crystals of 1,3,5-trinitro-S-triazine (RDX) using terahertz time-domain spectroscopy V. H. Whitley & D. E... of the incident radiation....

450

Techniques for synchronization of X-Ray pulses to the pump laser in an ultrafast X-Ray facility  

E-Print Network [OSTI]

synchronization of ultrafast x-ray pulses produced in theAccurate timing of ultrafast x-ray probe pulses emitted fromOF X-RAY PULSES TO THE PUMP LASER IN AN ULTRAFAST X-RAY

Corlett, J.N.; Doolittle, L.; Schoenlein, R.; Staples, J.; Wilcox, R.; Zholents, A.

2003-01-01T23:59:59.000Z

451

Total reflection inelastic x-ray scattering from a 10 nm thick La{sub 0.6}Sr{sub 0.2}CoO{sub 3} thin film.  

SciTech Connect (OSTI)

To study equilibrium changes in composition, valence, and electronic structure near the surface and into the bulk, we demonstrate the use of a new approach, total-reflection inelastic x-ray scattering, as a sub-keV spectroscopy capable of depth profiling chemical changes in thin films with nanometer resolution. By comparing data acquired under total x-ray reflection and penetrating conditions, we are able to separate the O K-edge spectra from a 10 nm La{sub 0.6}Sr{sub 0.4}CoO{sub 3} thin film from that of the underlying SrTiO{sub 3} substrate. With a smaller wavelength probe than comparable soft x-ray absorption measurements, we also describe the ability to easily access dipole-forbidden final states, using the dramatic evolution of the La N{sub 4,5} edge with momentum transfer as an example.

Fister, T. T.; Fong, D. D.; Eastman, J. A.; Iddir, H.; Zapol, P.; Fuoss, P. H.; Balasubramanian, M.; Gordon, R. A.; Balasubramaniam, K. R.; Salvador, P. A.; Simon Fraser Univ.; Carnegie Mellon Univ.

2011-01-18T23:59:59.000Z

452

X-ray fluorescence observations of the moon by SMART-1/D-CIXS and the first detection of Ti Ka from the lunar surface  

E-Print Network [OSTI]

X-ray fluorescence observations of the moon by SMART-1/D-CIXS and the first detection of Ti Ka from s t r a c t The demonstration of a compact imaging X-ray spectrometer (D-CIXS), which flew on ESA new technologies for orbital X-ray fluorescence spectroscopy. D-CIXS conducted observations

Wieczorek, Mark

453

Journal of Electron Spectroscopy and Related Phenomena 154 (2007) 6062 Investigation of vanadiumsodium silicate glasses using  

E-Print Network [OSTI]

­sodium silicate glasses using XANES spectroscopy M. Faiza,, A. Mekkia, B.S. Munb, Z. Hussainb a Surface Science. Keywords: XANES; Vanadium­sodium silicate glasses; V L2,3 edges; O K edge 1. Introduction Studies on oxide vanadium-sodium silicate glasses. X-ray absorption near edge structure (XANES) spectroscopy is a pow- erful

Mekki, Abdelkarim

454

Measurement of Water Vapor Concentration using Tunable Diode Laser Absorption Spectroscopy  

E-Print Network [OSTI]

Tunable diode laser spectroscopy and the Beer-Lambert relation has been used to measure the absorption of water vapor both in an absorption cell and in a shock tube. The purpose of this thesis is to develop a laser diagnostic capable of determining...

Barrett, Alexander B.

2010-07-14T23:59:59.000Z

455

Hard x-ray imaging from explorer  

SciTech Connect (OSTI)

Coded aperture X-ray detectors were applied to obtain large increases in sensitivity as well as angular resolution. A hard X-ray coded aperture detector concept is described which enables very high sensitivity studies persistent hard X-ray sources and gamma ray bursts. Coded aperture imaging is employed so that approx. 2 min source locations can be derived within a 3 deg field of view. Gamma bursts were located initially to within approx. 2 deg and X-ray/hard X-ray spectra and timing, as well as precise locations, derived for possible burst afterglow emission. It is