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Note: This page contains sample records for the topic "x-ray absorption fine" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
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We encourage you to perform a real-time search of NLEBeta
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1

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

2

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

3

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.

4

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

5

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

6

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.

7

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

8

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

9

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

10

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.

11

X-ray absorption spectroscopy  

E-Print Network [OSTI]

009-9473-8 REVIEW X-ray absorption spectroscopy Junko Yano and 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

12

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

13

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

14

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

15

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

16

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

17

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

18

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

19

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

20

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.

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


21

X-Ray Absorption Spectroscopy of 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.

22

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.

23

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

24

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

25

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

26

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

27

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

28

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

29

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

30

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

31

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

32

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

33

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

34

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 Laboratorys 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

35

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

36

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.

37

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 Festkrperphysik, Philipps-Universitt Marburg (Germany)] [Molekulare Festkrperphysik, Philipps-Universitt 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

38

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

39

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

40

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

Note: This page contains sample records for the topic "x-ray absorption fine" 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 spectroscopy at the Ni-K edge in Stackhousia tryonii Bailey hyperaccumulator  

E-Print Network [OSTI]

X-ray absorption spectroscopy at the NiK edge inin vivo by micro x-ray absorption spectroscopy (XAS) at theNiK edge. Both x-ray absorption near edge structure and

Kachenko, A.

2009-01-01T23:59:59.000Z

42

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.

43

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

44

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

45

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

46

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

47

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

48

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.

49

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

50

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

51

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

52

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

53

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

54

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.

55

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

56

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

57

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

58

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

59

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

60

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...

Note: This page contains sample records for the topic "x-ray absorption fine" 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

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

62

absorption fine structures: Topics by E-print Network  

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

absorption fine structures 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 Photon interference x-ray...

63

absorption fine structure: Topics by E-print Network  

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

absorption fine structure 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 Photon interference x-ray...

64

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

65

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

66

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, Loc; Dumont, A M; Czerny, B; Mouchet, M; Gonalves, A C; Goosmann, R W

2006-01-01T23:59:59.000Z

67

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

68

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

69

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

70

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

71

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

72

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

73

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.

74

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

75

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

76

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.

77

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

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

a measurement of the fraction of metallic Co. Any quantitative understanding of magnetism in this system needs to take account of both types of Co. Results are reported for...

78

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

79

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 fr Materialien und Energie, Institute of Solar Fuels, Albert-Einstein-Strae 15, 12489 Berlin (Germany); Golnak, R.; Xiao, J. [Helmholtz-Zentrum Berlin fr Materialien und Energie, Institute of Methods for Material Development, Albert-Einstein-Strae 15, 12489 Berlin (Germany)

2014-10-15T23:59:59.000Z

80

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

Note: This page contains sample records for the topic "x-ray absorption fine" from the National Library of EnergyBeta (NLEBeta).
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81

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

82

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; Mchler, Jean-Pierre [Institute for Chemical and Bioengineering, ETH Zrich, CH-8093 Zrich (Switzerland)] [Institute for Chemical and Bioengineering, ETH Zrich, CH-8093 Zrich (Switzerland); Jordan, Inga; Wrner, Hans Jakob [Laboratory of Physical Chemistry, ETH Zrich, CH-8093 Zrich (Switzerland)] [Laboratory of Physical Chemistry, ETH Zrich, CH-8093 Zrich (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 Zrich, CH-8093 Zrich (Switzerland) [Institute for Chemical and Bioengineering, ETH Zrich, CH-8093 Zrich (Switzerland); Paul Scherrer Institute, CH-5232 Villigen PSI (Switzerland)

2013-07-15T23:59:59.000Z

83

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

84

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.

85

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

86

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

87

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...

88

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

89

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

SciTech Connect (OSTI)

The local structure of nanoscale (?1040 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 LiCo 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

90

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

91

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

92

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

93

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.; Nemk, 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); Trndahl, T.; Fjllstrm, V. [ngstrm 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

94

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

95

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

96

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

97

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

98

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

99

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

100

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.

Loc Chevallier; Suzy Collin; Anne-Marie Dumont; Bozena Czerny; Martine Mouchet; Anabela C. Gonalves; Ren Goosmann

2005-11-01T23:59:59.000Z

Note: This page contains sample records for the topic "x-ray absorption fine" from the National Library of EnergyBeta (NLEBeta).
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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

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

102

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

103

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

104

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

105

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

106

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

107

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

108

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

109

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

110

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

111

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

112

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

113

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

114

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

115

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

116

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

117

(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

118

[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

119

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.

120

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

Note: This page contains sample records for the topic "x-ray absorption fine" 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

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

122

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

123

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

124

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

125

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-Prez, Rafael; Botti, Silvana, E-mail: silvana.botti@univ-lyon1.fr [Institut Lumire Matire and ETSF, UMR5306 Universit Lyon 1-CNRS, Universit de Lyon, F-69622 Villeurbanne Cedex (France); Schnohr, Claudia S., E-mail: c.schnohr@uni-jena.de [Institut fr Festkrperphysik, Friedrich-Schiller-Universitt Jena, Max-Wien-Platz 1, 07743 Jena (Germany); Lauermann, Iver [Helmholtz-Zentrum Berlin fr Materialien und Energie, Hahn-Meitner Platz 1, 14109 Berlin (Germany); Rubio, Angel [Nano-Bio Spectroscopy Group and ETSF Scientific Development Centre, Departamento de Fsica de Materiales, Centro de Fsica de Materiales CSIC-MPC and DIPC, Universidad del Pas Vasco UPV/EHU, Avenida de Tolosa 72, E-20018 San Sebastin (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

126

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

127

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

128

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

129

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

130

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

131

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

132

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

133

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

134

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.

135

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

136

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

137

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

138

Photoluminescence and Extended X-ray Absorption Fine Structure Studies on CdTe Material.  

E-Print Network [OSTI]

??The direct-band-gap semiconductor CdTe is an important material for fabricating high efficiency, polycrystalline thin-film solar cells in a heterojunction configuration. The outstanding physical properties of (more)

Liu, Xiangxin

2006-01-01T23:59:59.000Z

139

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

140

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

Note: This page contains sample records for the topic "x-ray absorption fine" 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

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

142

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

143

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, Notkestrae 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

144

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

145

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

146

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

147

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

148

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

149

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

150

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

151

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

152

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

153

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

154

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

155

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

156

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

157

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

158

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); Universitt Wrzburg, Experimentelle Physik VII, Am Hubland, 97074 Wrzburg (Germany); Gemeinschaftslabor fr 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. [Universitt Wrzburg, Experimentelle Physik VII, Am Hubland, 97074 Wrzburg (Germany)] [Universitt Wrzburg, Experimentelle Physik VII, Am Hubland, 97074 Wrzburg (Germany); Wilks, R. G. [Solar Energy Research, Helmholtz-Zentrum Berlin fr Materialien und Energie GmbH, Hahn-Meitner-Platz 1, 14109 Berlin (Germany)] [Solar Energy Research, Helmholtz-Zentrum Berlin fr 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); Br, 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 fr Materialien und Energie GmbH, Hahn-Meitner-Platz 1, 14109 Berlin (Germany); Insitut fr Physik und Chemie, Brandenburgische Technische Universitt Cottbus-Senftenberg, Konrad-Wachsmann-Allee 1, 03046 Cottbus (Germany); and others

2014-01-15T23:59:59.000Z

159

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

160

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

Note: This page contains sample records for the topic "x-ray absorption fine" from the National Library of EnergyBeta (NLEBeta).
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161

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

162

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

163

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

164

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

165

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

166

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

167

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

168

Chromatic X-Ray imaging with a fine pitch CdTe sensor coupled to a large area photon counting pixel ASIC  

E-Print Network [OSTI]

An innovative X-ray imaging sensor with intrinsic digital characteristics is presented. It is based on Chromatic Photon Counting technology. The detector is able to count individually the incident X-ray photons and to separate them according to their energy (two 'color' images per exposure). The energy selection occurs in real time and at radiographic imaging speed (GHz global counting rate). Photon counting, color mode and a very high spatial resolution (more than 10 l.p./mm at MTF50) allow to obtain an optimal ratio between image quality and absorbed dose. The individual block of the imaging system is a two-side buttable semiconductor radiation detector made of a thin pixellated CdTe crystal (the sensor) coupled to a large area VLSI CMOS pixel ASIC. 1, 2, 4, 8 tile units have been built. The 8 tiles unit has 25cm x 2.5cm sensitive area. Results and images obtained from in depth testing of several configurations of the system are presented. The X-Ray imaging system is the technological platform of PIXIRAD Im...

Bellazzini, R; Brez, A; Minuti, M; Pinchera, M; Mozzo, P

2012-01-01T23:59:59.000Z

169

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

170

In Situ X-ray Absorption Fine Structure Studies on the Effect of pH on Pt  

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 MayAtmospheric Optical Depth7-1D: Vegetation ProposedUsingFun withconfinementEtching.348 270 300Aptamers and GraphenePhase EvolutionIn

171

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

172

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

173

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

174

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

175

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.

176

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

177

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

178

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

179

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

180

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

Note: This page contains sample records for the topic "x-ray absorption fine" 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 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

182

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

183

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

184

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

185

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

186

A novel instrument for quantitative nanoanalytics involving complementary X-ray methodologies  

SciTech Connect (OSTI)

A novel ultra-high vacuum instrument for X-ray reflectometry and spectrometry-related techniques for nanoanalytics by means of synchrotron radiation has been constructed and commissioned. This versatile instrument was developed by the Physikalisch-Technische Bundesanstalt, Germany's national metrology institute, and includes a 9-axis manipulator that allows for an independent alignment of the samples with respect to all degrees of freedom. In addition, a rotational and translational movement of several photodiodes as well as a translational movement of an aperture system in and out of the beam is provided. Thus, the new instrument enables various analytical techniques based on energy dispersive X-ray detectors such as reference-free X-ray fluorescence analysis (XRF), total-reflection XRF, grazing-incidence XRF in addition to optional X-ray reflectometry measurements or polarization-dependent X-ray absorption fine structure analyses. With this instrument samples having a size of up to 100 mm Multiplication-Sign 100 mm can be analyzed with respect to their mass deposition, elemental or spatial composition, or the species in order to probe surface contamination, layer composition and thickness, the depth profile of matrix elements or implants, the species of nanolayers, nanoparticles or buried interfaces as well as the molecular orientation of bonds. Selected applications of this advanced ultra-high vacuum instrument demonstrate both its flexibility and capability.

Lubeck, J.; Beckhoff, B.; Fliegauf, R.; Holfelder, I.; Hoenicke, P.; Mueller, M.; Pollakowski, B.; Reinhardt, F.; Weser, J. [Physikalisch-Technische Bundesanstalt, Abbestr. 2-12, 10587 Berlin (Germany)

2013-04-15T23:59:59.000Z

187

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

188

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

189

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

190

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 13?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

191

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

192

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

193

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

194

absorption fine-structure spectroscopy: Topics by E-print Network  

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

absorption fine-structure spectroscopy 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 Effect of...

195

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

196

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

197

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

198

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

199

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

200

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

Note: This page contains sample records for the topic "x-ray absorption fine" 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

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

202

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

203

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...

204

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.

205

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

206

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

207

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...

208

Laboratory-size three-dimensional x-ray microscope with Wolter type I mirror optics and an electron-impact water window x-ray source  

SciTech Connect (OSTI)

We constructed a laboratory-size three-dimensional water window x-ray microscope that combines wide-field transmission x-ray microscopy with tomographic reconstruction techniques, and observed bio-medical samples to evaluate its applicability to life science research fields. It consists of a condenser and an objective grazing incidence Wolter type I mirror, an electron-impact type oxygen K? x-ray source, and a back-illuminated CCD for x-ray imaging. A spatial resolution limit of around 1.0 line pairs per micrometer was obtained for two-dimensional transmission images, and 1-?m scale three-dimensional fine structures were resolved.

Ohsuka, Shinji, E-mail: ohsuka@crl.hpk.co.jp [Hamamatsu Photonics K.K., 5000 Hirakuchi, Hamakita-ku, Hamamatsu-City, 434-8601 (Japan); The Graduate School for the Creation of New Photonics Industries, 1955-1 Kurematsu-cho, Nishi-ku, Hamamatsu-City, 431-1202 (Japan); Ohba, Akira; Onoda, Shinobu; Nakamoto, Katsuhiro [Hamamatsu Photonics K.K., 5000 Hirakuchi, Hamakita-ku, Hamamatsu-City, 434-8601 (Japan); Nakano, Tomoyasu [Hamamatsu Photonics K.K., 5000 Hirakuchi, Hamakita-ku, Hamamatsu-City, 434-8601 (Japan); Ray-Focus Co. Ltd., 6009 Shinpara, Hamakita-ku, Hamamatsu-City, 434-0003 (Japan); Miyoshi, Motosuke; Soda, Keita; Hamakubo, Takao [Research Center for Advanced Science and Technology, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8904 (Japan)

2014-09-15T23:59:59.000Z

209

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

210

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.

211

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

212

Direct detection of x-rays for protein crystallography employing a thick, large area CCD  

DOE Patents [OSTI]

An apparatus and method for directly determining the crystalline structure of a protein crystal. The crystal is irradiated by a finely collimated x-ray beam. The interaction of the x-ray beam with the crystal produces scattered x-rays. These scattered x-rays are detected by means of a large area, thick CCD which is capable of measuring a significant number of scattered x-rays which impact its surface. The CCD is capable of detecting the position of impact of the scattered x-ray on the surface of the CCD and the quantity of scattered x-rays which impact the same cell or pixel. This data is then processed in real-time and the processed data is outputted to produce a image of the structure of the crystal. If this crystal is a protein the molecular structure of the protein can be determined from the data received.

Atac, Muzaffer (Wheaton, IL); McKay, Timothy (Ann Arbor, MI)

1999-01-01T23:59:59.000Z

213

An application of Ti-K X-ray absorption edges and fine structures to the study of substoichiometric titanium carbide TiC1-x  

E-Print Network [OSTI]

remarkable physical proper- ties, cubic rocksalt transition metal carbides present a large domain of substoichiometric titanium carbide TiC1-x V. Moisy-Maurice and C. H. de Novion C.E.A./IRDI/DMECN/DTech, Laboratoire concentration on the bulk physical properties of the carbides has been extensively studied [2] ; but a detailed

Paris-Sud XI, Université de

214

Dopant site selectivity in BaCe0.85M0.15O3-by extended x-ray absorption fine structure  

E-Print Network [OSTI]

Material Science, California Institute of Technology, Pasadena, California 91125 S. M. Webb and S. Brennan, California Institute of Technology, Pasadena, California 91125 Received 17 February 2004; accepted 12, and thereby introduce oxygen vacancies into the perovskite structure. Recent studies indicate the possibility

Haile, Sossina M.

215

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. Hmlinen

2006-08-29T23:59:59.000Z

216

Quasi-Moseley's law for strong narrow bandwidth soft x-ray sources containing higher charge-state ions  

SciTech Connect (OSTI)

Bright narrow band emission observed in optically thin plasmas of high-Z elements in the extreme ultraviolet spectral region follows a quasi-Moseley's law. The peak wavelength can be expressed as ?=(21.8612.09)R{sub ?}{sup ?1}(Z?(23.232.87)){sup ?(1.520.12)}, where R{sub ?} is the Rydberg constant. The wavelength varies from 13.5?nm to 4.0?nm as the atomic number, Z, increases from Z?=?50 to Z?=?83. The range of emission wavelengths available from hot optically thin plasmas permits the development of bright laboratory-scale sources for applications including x-ray microscopy and x-ray absorption fine structure determination.

Ohashi, Hayato, E-mail: ohashi@eng.u-toyama.ac.jp; Higashiguchi, Takeshi, E-mail: higashi@cc.utsunomiya-u.ac.jp; Suzuki, Yuhei; Arai, Goki; Otani, Yukitoshi; Yatagai, Toyohiko [Department of Advanced Interdisciplinary Sciences, Center for Optical Research and Education (CORE), Utsunomiya University, Utsunomiya, Tochigi 321-8585 (Japan); Li, Bowen [School of Nuclear Science and Technology, Lanzhou University, Lanzhou 730000 (China); Dunne, Padraig; O'Sullivan, Gerry [School of Physics, University College Dublin, Belfield, Dublin 4 (Ireland); Jiang, Weihua [Department of Electrical Engineering, Nagaoka University of Technology, Nagaoka, Niigata 940-2188 (Japan); Endo, Akira [HiLASE Project, Institute of Physics, Academy of Sciences CR, Na Slovance 2, 18221 Prague 8 (Czech Republic); Sakaue, Hiroyuki A.; Kato, Daiji; Murakami, Izumi; Tamura, Naoki; Sudo, Shigeru; Suzuki, Chihiro [National Institute for Fusion Science, Toki, Gifu 509-5292 (Japan); Koike, Fumihiro [Faculty of Science and Technology, Sophia University, Chiyoda, Tokyo 102-8554 (Japan)

2014-06-09T23:59:59.000Z

217

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

218

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

219

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

220

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

Note: This page contains sample records for the topic "x-ray absorption fine" 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

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

222

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

223

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

224

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

225

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

226

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...

227

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...

228

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

229

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

230

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

231

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

232

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

233

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

234

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

235

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

236

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

237

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

238

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

239

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

240

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"

Note: This page contains sample records for the topic "x-ray absorption fine" 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

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

242

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

243

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

244

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

245

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

246

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

247

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

248

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

249

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

250

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

251

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

252

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

253

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

254

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 suggested that hard X-ray imaging should be conducted from an Explorer mission where long exposure times are possible.

Grindlay, J.E.; Murray, S.S.

1981-11-01T23:59:59.000Z

255

X-ray laser frequency near-doubling and generation of tunable coherent x rays in plasma  

E-Print Network [OSTI]

X-ray laser frequency near-doubling and generation of tunable coherent x rays in plasma P. L plasmas in which efficient x-ray laser frequency near-doubling is expected for a number of available x-ray of coherent x rays and tunable optical radiation may result in tunable coherent x-ray radiation powerful

Kaplan, Alexander

256

High speed x-ray beam chopper  

DOE Patents [OSTI]

A fast, economical, and compact x-ray beam chopper with a small mass and a small moment of inertia whose rotation can be synchronized and phase locked to an electronic signal from an x-ray source and be monitored by a light beam is disclosed. X-ray bursts shorter than 2.5 microseconds have been produced with a jitter time of less than 3 ns.

McPherson, Armon (Oswego, IL); Mills, Dennis M. (Naperville, IL)

2002-01-01T23:59:59.000Z

257

X-ray populations in galaxies  

E-Print Network [OSTI]

Today's sensistive, high resolution Chandra X-ray observations allow the study of many populations of X-ray sources. The traditional astronomical tools of photometric diagrams and luminosity functions are now applied to these populations, and provide the means for classifying the X-ray sources and probing their evolution. While overall stellar mass drives the amount of X-ray binaries in old stellar population, the amount of sources in star-forming galaxies is related to the star formation rate. Shart-lived, luminous, high mass binaries (HNXBs) dominate these young populations.

G. Fabbiano

2005-11-09T23:59:59.000Z

258

X-RAY MICROBEAM SPEECH PRODUCTION DATABASE  

E-Print Network [OSTI]

X-RAY MICROBEAM SPEECH PRODUCTION DATABASE USER'S HANDBOOK Version 1.0 (June 1994) prepared by John . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Chapter Two: XRMB History

259

X-ray laser microscope apparatus  

DOE Patents [OSTI]

A microscope consisting of an x-ray contact microscope and an optical microscope. The optical, phase contrast, microscope is used to align a target with respect to a source of soft x-rays. The source of soft x-rays preferably comprises an x-ray laser but could comprise a synchrotron or other pulse source of x-rays. Transparent resist material is used to support the target. The optical microscope is located on the opposite side of the transparent resist material from the target and is employed to align the target with respect to the anticipated soft x-ray laser beam. After alignment with the use of the optical microscope, the target is exposed to the soft x-ray laser beam. The x-ray sensitive transparent resist material whose chemical bonds are altered by the x-ray beam passing through the target mater GOVERNMENT LICENSE RIGHTS This invention was made with government support under Contract No. De-FG02-86ER13609 awarded by the Department of Energy. The Government has certain rights in this invention.

Suckewer, Szymon (Princeton, NJ); DiCicco, Darrell S. (Plainsboro, NJ); Hirschberg, Joseph G. (Coral Gables, FL); Meixler, Lewis D. (East Windsor, NJ); Sathre, Robert (Princeton, NJ); Skinner, Charles H. (Lawrenceville, NJ)

1990-01-01T23:59:59.000Z

260

Compound refractive X-ray lens  

DOE Patents [OSTI]

An apparatus and method for focusing X-rays. In one embodiment, his invention is a commercial-grade compound refractive X-ray lens. The commercial-grade compound refractive X-ray lens includes a volume of low-Z material. The volume of low-Z material has a first surface which is adapted to receive X-rays of commercially-applicable power emitted from a commercial-grade X-ray source. The volume of low-Z material also has a second surface from which emerge the X-rays of commercially-applicable power which were received at the first surface. Additionally, the commercial-grade compound refractive X-ray lens includes a plurality of openings which are disposed between the first surface and the second surface. The plurality of openings are oriented such that the X-rays of commercially-applicable power which are received at the first surface, pass through the volume of low-Z material and through the plurality openings. In so doing, the X-rays which emerge from the second surface are refracted to a focal point.

Nygren, David R. (Berkeley, CA); Cahn, Robert (Walnut Creek, CA); Cederstrom, Bjorn (Traellborg, SE); Danielsson, Mats (Stocksund, SE); Vestlund, Jonas (Stockholm, SE)

2000-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "x-ray absorption fine" 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

X-Ray Science Division (XSD)  

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

X-Ray Science Division (XSD) Search Button About Welcome Overview Visiting the APS Mission & Goals Find People Organization Charts Committees Job Openings User Information...

262

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

263

Ultraluminous X-ray Sources: The most extreme X-ray binaries  

E-Print Network [OSTI]

1 Ultraluminous X-ray Sources: The most extreme X-ray binaries Luca Zampieri INAF ULXs ­ Lubiana ­ May 11, 2012- LZ #12;6 · X-ray observations of nearby galaxies show a population of pointlike, off-nuclear sources with L >> Ledd for 1 Msun (L>1.0e39 erg/s) UltraLuminous X-ray Sources (e

?umer, Slobodan

264

X-ray Diffraction (XRD) 1.0 What is X-ray Diffraction  

E-Print Network [OSTI]

X-ray Diffraction (XRD) · 1.0 What is X-ray Diffraction · 2.0 Basics of Crystallography · 3.0 Production of X-rays · 4.0 Applications of XRD · 5.0 Instrumental Sources of Error · 6.0 Conclusions #12 why the cleavage faces of crystals appear to reflect X-ray beams at certain angles of incidence (theta

Moeck, Peter

265

X-ray source populations in galaxies  

E-Print Network [OSTI]

Today's sensitive, high-resolution X-ray observations allow the study of populations of X-ray sources, in the luminosity range of Galactic X-ray binaries, in galaxies as distant as 20-30 Mpc. The traditional astronomical tools of photometric diagrams and luminosity functions are now applied to these populations, providing a direct probe of the evolved binary component of different stellar populations. The study of the X-ray populations of E and S0 galaxies has revamped the debate on the formation and evolution of low-mass X-ray binaries (LMXBs) and on the role of globular clusters in these processes. While overall stellar mass drives the amount of X-ray binaries in old stellar populations, the amount of sources in star forming galaxies is related to the star formation rate. Short-lived, luminous, high-mass binaries (HMXBs) dominate these young populations. The most luminous sources in these systems are the debated ULXs, which have been suggested to be ~100-1000 Msol black holes, but could alternatively include a number of binaries with stellar mass black holes. Very soft sources have also been discovered in many galaxies and their nature is currently being debated. Observations of the deep X-ray sky, and comparison with deep optical surveys, are providing the first evidence of the X-ray evolution of galaxies.

G. Fabbiano

2005-11-16T23:59:59.000Z

266

Aneta Siemiginowska Chandra X-ray Center  

E-Print Network [OSTI]

-ray and gamma-ray · High Energy Sky · Chandra X-ray Observatory · examples of typical X-ray data, · an example of a data analysis process · statistical challenges · what do we learn from the data? #12;What is Astronomy and phenomena do we study and how? Solar System: Sun and sollar wind, planets, moons, asteroids, comets Our

Wolfe, Patrick J.

267

Phased Contrast X-Ray Imaging  

ScienceCinema (OSTI)

The Pacific Northwest National Laboratory is developing a range of technologies to broaden the field of explosives detection. Phased contrast X-ray imaging, which uses silicon gratings to detect distortions in the X-ray wave front, may be applicable to mail or luggage scanning for explosives; it can also be used in detecting other contraband, small-parts inspection, or materials characterization.

Erin Miller

2012-12-31T23:59:59.000Z

268

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

269

Quantitative Measurements of X-ray Intensity  

SciTech Connect (OSTI)

This chapter describes the characterization of several X-ray sources and their use in calibrating different types of X-ray cameras at National Security Technologies, LLC (NSTec). The cameras are employed in experimental plasma studies at Lawrence Livermore National Laboratory (LLNL), including the National Ignition Facility (NIF). The sources provide X-rays in the energy range from several hundred eV to 110 keV. The key to this effort is measuring the X-ray beam intensity accurately and traceable to international standards. This is accomplished using photodiodes of several types that are calibrated using radioactive sources and a synchrotron source using methods and materials that are traceable to the U.S. National Institute of Standards and Technology (NIST). The accreditation procedures are described. The chapter begins with an introduction to the fundamental concepts of X-ray physics. The types of X-ray sources that are used for device calibration are described. The next section describes the photodiode types that are used for measuring X-ray intensity: power measuring photodiodes, energy dispersive photodiodes, and cameras comprising photodiodes as pixel elements. Following their description, the methods used to calibrate the primary detectors, the power measuring photodiodes and the energy dispersive photodiodes, as well as the method used to get traceability to international standards are described. The X-ray source beams can then be measured using the primary detectors. The final section then describes the use of the calibrated X-ray beams to calibrate X-ray cameras. Many of the references are web sites that provide databases, explanations of the data and how it was generated, and data calculations for specific cases. Several general reference books related to the major topics are included. Papers expanding some subjects are cited.

Haugh, M. J., Schneider, M.

2011-09-01T23:59:59.000Z

270

X-ray Practicals Series 1 Advanced Data Reduction  

E-Print Network [OSTI]

X-ray Practicals Series 1 Advanced Data Reduction Instructor J. Reibenspies, Ph. D. Nattamai Bhuvanesh, Ph.D. Version 1.0.0 #12;X-ray Practicals Series 2 #12;X-ray Practicals Series 3 #12;X-ray is good. The y direction is shifting the most, but the shift is ok #12;X-ray Practicals Series 5 Other

Meagher, Mary

271

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.

272

X-RAY EMISSION FROM PLANETS AND COMETS: RELATIONSHIP WITH SOLAR X-RAYS AND SOLAR WIND  

E-Print Network [OSTI]

with the occurrence of solar X-ray flare, when light travel time delay is accounted, suggesting that X-rays fromX-RAY EMISSION FROM PLANETS AND COMETS: RELATIONSHIP WITH SOLAR X-RAYS AND SOLAR WIND ANIL BHARDWAJ Flight center, Greenbelt, MD 20771, USA Scattering of solar X-ray radiation mainly produces the non

?stgaard, Nikolai

273

X-Ray Diffraction The X-Ray Diffraction facility is equipped with state-of-the-art  

E-Print Network [OSTI]

X-Ray Diffraction The X-Ray Diffraction facility is equipped with state-of-the-art diffractometers offering both single crystal and powder X-Ray diffraction. Powder X-Ray Diffraction High resolution data For more details on powder X-Ray analysis contact Dr J Hriljac on 0121 414 4458 or email: j

Birmingham, University of

274

Novel X-Ray Imaging Opportunities for the RPI Linear Accelerator's Tunable, Quasi-monochromatic X-ray Source  

E-Print Network [OSTI]

Novel X-Ray Imaging Opportunities for the RPI Linear Accelerator's Tunable, Quasi-monochromatic X-ray of an intense, tunable, polarized, and quasi-monochromatic X-ray source has been ongoing at Rensselaer Polytechnic Institute since 2001 [1, 2, 3, 4, 5, 6]. This X-ray source, known as Parametric X-rays (PXR

Danon, Yaron

275

X-Ray Physics in Confinement  

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 Energy WorldwideX-RayX-RayX-Ray

276

X-ray Spectral Survey of WGACAT Quasars, II: Optical and Radio Properties of Quasars with Low Energy X-ray Cut-offs  

E-Print Network [OSTI]

We have selected quasars with X-ray colors suggestive of a low energy cut-off, from the ROSAT PSPC pointed archive. We examine the radio and optical properties of these 13 quasars. Five out of the seven quasars with good optical spectra show associated optical absorption lines, with two having high delta-v candidate systems. Two other cut-off quasars show reddening associated with the quasar. We conclude that absorption is highly likely to be the cause of the X-ray cut-offs, and that the absorbing material associated with the quasars, not intervening along the line-of-sight. The suggestion that Gigahertz Peaked Sources are associated with X-ray cut-offs remains unclear with this expanded sample.

Martin Elvis; Fabrizio Fiore; Paolo Giommi; Paolo Padovani

1997-08-05T23:59:59.000Z

277

Biological Imaging by Soft X-Ray Diffraction Microscopy  

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

Biological Imaging by Soft X-Ray Diffraction Microscopy Biological Imaging by Soft X-Ray Diffraction Microscopy Print Wednesday, 30 November 2005 00:00 Electron and x-ray...

278

Polarization of absorption lines as a diagnostics of circumstellar, interstellar and intergalactic magnetic fields: Fine structure atoms  

E-Print Network [OSTI]

The relative population of the fine structure sublevels of an atom's ground state is affected by radiative transitions induced by an anisotropic radiation flux. This causes the alignment of atomic angular momentum. In terms of observational consequences for the interstellar and intergalactic medium, this results in the polarization of the absorption lines. In the paper we consider the conditions necessary for this effect and provide calculations of polarization from a few astrophysically important atoms and ions with multiple upper and lower levels for an arbitrary orientation of magnetic fields to the a) source of optical pumping, b) direction of observation, c) absorbed source. We also consider an astrophysically important ``degenerate'' case when the source of optical pumping coincides with the source of the absorbed radiation. We present analytical expressions that relate the degree of linear polarization and the intensity of absorption to the 3D orientation of the magnetic field with respect to the pumping source, the source of the absorbed radiation, and the direction of observations. We discuss how all these parameters can be determined via simultaneous observations of several absorption lines and suggest graphical means that are helpful in practical data interpretation. We prove that studies of absorption line polarization provide a unique tool to study 3D magnetic field topology in various astrophysical conditions.

Huirong Yan; A. Lazarian

2006-11-09T23:59:59.000Z

279

X-ray Modeling of \\eta\\ Carinae and WR140 from SPH Simulations  

E-Print Network [OSTI]

The colliding wind binary (CWB) systems \\eta\\ Carinae and WR140 provide unique laboratories for X-ray astrophysics. Their wind-wind collisions produce hard X-rays that have been monitored extensively by several X-ray telescopes, including RXTE. To interpret these RXTE X-ray light curves, we model the wind-wind collision using 3D smoothed particle hydrodynamics (SPH) simulations. Adiabatic simulations that account for the absorption of X-rays from an assumed point source at the apex of the wind-collision shock cone by the distorted winds can closely match the observed 2-10keV RXTE light curves of both \\eta\\ Car and WR140. This point-source model can also explain the early recovery of \\eta\\ Car's X-ray light curve from the 2009.0 minimum by a factor of 2-4 reduction in the mass loss rate of \\eta\\ Car. Our more recent models relax the point-source approximation and account for the spatially extended emission along the wind-wind interaction shock front. For WR140, the computed X-ray light curve again matches the ...

Russell, Christopher M P; Okazaki, Atsuo T; Madura, Thomas I; Owocki, Stanley P

2011-01-01T23:59:59.000Z

280

STATE-DEPENDENT ORBITAL MODULATION OF X-RAYS IN CYG X-3  

SciTech Connect (OSTI)

We analyze all of the available RXTE observations of Cyg X-3 in order to investigate the connection between the central X-ray source and its surrounding environment. The hardness-intensity diagram of Cyg X-3 displays a 'shoe' shape rather than the Q-type shape commonly seen in other black hole X-ray binary, and exhibits no apparent hysteresis effect. During the {gamma}-ray outbursts, no existing data are located in the hard and intermediate states, which suggest the absence of a significant population of non-thermal electrons when the source is in these states. For the first time, we present the orbital modulation of the X-ray light curve (LC) of all five states. The different energy band LCs are in phase with each other in all five states, and the modulation amplitude of both soft and hard X-ray LCs monotonously increases with decreasing hardness from hard to soft non-thermal states. We confirm that the modulation depth decreases with increasing energy in the hard, intermediate, and very high states, as originally reported by Zdziarski et al. However, in the soft non-thermal state, the hard X-ray modulation strength significantly increases and is even larger than the soft X-ray one. Our results rule out both wind absorption and jet origins of the hard X-ray LC modulation in the soft non-thermal state, and challenge our understanding of the states of Cyg X-3.

Weng, Shan-Shan; Zhang, Shuang-Nan; Ge, Ming-Yu; Li, Jian; Zhang, Shu, E-mail: zhangsn@ihep.ac.cn, E-mail: wengss@ihep.ac.cn [Key Laboratory of Particle Astrophysics, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049 (China)] [Key Laboratory of Particle Astrophysics, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049 (China)

2013-01-20T23:59:59.000Z

Note: This page contains sample records for the topic "x-ray absorption fine" 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

Small Angle X-Ray Scattering Detector  

DOE Patents [OSTI]

A detector for time-resolved small-angle x-ray scattering includes a nearly constant diameter, evacuated linear tube having an end plate detector with a first fluorescent screen and concentric rings of first fiber optic bundles for low angle scattering detection and an annular detector having a second fluorescent screen and second fiber optic bundles concentrically disposed about the tube for higher angle scattering detection. With the scattering source, i.e., the specimen under investigation, located outside of the evacuated tube on the tube's longitudinal axis, scattered x-rays are detected by the fiber optic bundles, to each of which is coupled a respective photodetector, to provide a measurement resolution, i.e., dq/q, where q is the momentum transferred from an incident x-ray to an x-ray scattering specimen, of 2% over two (2) orders of magnitude in reciprocal space, i.e., qmax/qmin approx=lO0.

Hessler, Jan P.

2004-06-15T23:59:59.000Z

282

X-ray grid-detector apparatus  

DOE Patents [OSTI]

A hybrid grid-detector apparatus for x-ray systems wherein a microchannel plate structure has an air-interspaced grid portion and a phosphor/optical fluid-filled grid portion. The grids are defined by multiple adjacent channels separated by lead-glass septa. X-rays entering the air-interspaced grid portion at an angle of impingement upon the septa are attenuated, while non-impinging x-rays pass through to the phosphor/fluid filled portion. X-ray energy is converted to luminescent energy in the phosphor/fluid filled portion and the resultant beams of light are directed out of the phosphor/optical fluid filled portion to an imaging device.

Boone, John M. (Folsom, CA); Lane, Stephen M. (Oakland, CA)

1998-01-27T23:59:59.000Z

283

X-ray source for mammography  

DOE Patents [OSTI]

An x-ray source utilizing anode material which shifts the output spectrum to higher energy and thereby obtains higher penetrating ability for screening mammography application, than the currently utilized anode material. The currently used anode material (molybdenum) produces an energy x-ray spectrum of 17.5/19.6 keV, which using the anode material of this invention (e.g. silver, rhodium, and tungsten) the x-ray spectrum would be in the 20-35 keV region. Thus, the anode material of this invention provides for imaging of breasts with higher than average x-ray opacity without increase of the radiation dose, and thus reduces the risk of induced breast cancer due to the radiation dose administered for mammograms.

Logan, Clinton M. (Pleasanton, CA)

1994-01-01T23:59:59.000Z

284

Columbia University X-Ray Measurements  

E-Print Network [OSTI]

Columbia University X-Ray Measurements of the Levitated Dipole Experiment J. L. Ellsworth, J. Kesner MIT Plasma Science and Fusion Center D.T. Garnier, A.K. Hansen, M.E. Mauel Columbia University

285

X-Ray Nanoimaging: Instruments and Methods  

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

X-Ray Nanoimaging: Instruments and Methods To be held as part of SPIE. http:spie.orgOP318 August 28-29, 2013; San Diego, California, USA...

286

X-ray source for mammography  

DOE Patents [OSTI]

An x-ray source is described utilizing anode material which shifts the output spectrum to higher energy and thereby obtains higher penetrating ability for screening mammography application, than the currently utilized anode material. The currently used anode material (molybdenum) produces an energy x-ray spectrum of 17.5/19.6 keV, which using the anode material of this invention (e.g. silver, rhodium, and tungsten) the x-ray spectrum would be in the 20-35 keV region. Thus, the anode material of this invention provides for imaging of breasts with higher than average x-ray opacity without increase of the radiation dose, and thus reduces the risk of induced breast cancer due to the radiation dose administered for mammograms. 6 figures.

Logan, C.M.

1994-12-20T23:59:59.000Z

287

Principles of X-ray Navigation  

SciTech Connect (OSTI)

X-ray navigation is a new concept in satellite navigation in which orientation, position and time are measured by observing stellar emissions in x-ray wavelengths. X-ray navigation offers the opportunity for a single instrument to be used to measure these parameters autonomously. Furthermore, this concept is not limited to missions in close proximity to the earth. X-ray navigation can be used on a variety of missions from satellites in low earth orbit to spacecraft on interplanetary missions. In 1997 the Unconventional Stellar Aspect Experiment (USA) will be launched as part of the Advanced Research and Global Observation Satellite (ARGOS). USA will provide the first platform for real-time experimentation in the field of x-ray navigation and also serves as an excellent case study for the design and manufacturing of space qualified systems in small, autonomous groups. Current techniques for determining the orientation of a satellite rely on observations of the earth, sun and stars in infrared, visible or ultraviolet wavelengths. It is possible to use x-ray imaging devices to provide arcsecond level measurement of attitude based on star patterns in the x-ray sky. This technique is explored with a simple simulation. Collimated x-ray detectors can be used on spinning satellites to provide a cheap and reliable measure of orientation. This is demonstrated using observations of the Crab Pulsar taken by the high Energy Astronomy Observatory (HEAO-1) in 1977. A single instrument concept is shown to be effective, but dependent on an a priori estimate of the guide star intensity and thus susceptible to errors in that estimate. A star scanner based on a differential measurement from two x-ray detectors eliminates the need for an a priori estimate of the guide star intensity. A first order model and a second order model of the two star scanner concepts are considered. Many of the stars that emit in the x-ray regime are also x-ray pulsars with frequency stability approaching a part in 10{sup 9}. By observing these pulsations, a satellite can keep accurate time autonomously. They have demonstrated the acquisition and tracking of the Crab nebula pulsar by simulating the operation of a phase-locked loop.

Hanson, John Eric; /SLAC

2006-03-17T23:59:59.000Z

288

Hard X-ray Fluorescence Measurements of Heteroepitaxial Solid...  

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

Hard X-ray Fluorescence Measurements of Heteroepitaxial Solid Oxide Fuel Cell Cathode Materials. Hard X-ray Fluorescence Measurements of Heteroepitaxial Solid Oxide Fuel Cell...

289

Using X-Ray Computed Tomography in Pore Structure Characterization...  

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

Using X-Ray Computed Tomography in Pore Structure Characterization for a Berea Sandstone: Resolution Effect. Using X-Ray Computed Tomography in Pore Structure Characterization for...

290

X-ray Lenses Fabricated by LIGA Technology  

SciTech Connect (OSTI)

X-ray refractive optical lens systems have been successfully elaborated, designed, fabricated at the Institute for Microstructure Technology at the Forschungszentrum Karlsruhe (Germany) using LIGA technology in recent years. The lenses are structured in a SU-8 polymer. The capability of the LIGA technique to create an arbitrary profile of the focusing microstructures allow the fabrication of lenses with different curvature radius of parabolic geometry, minimized absorption and a large depth of focus. Also a set of planar lens systems on one substrate can be realized with 17 lenses providing identical focal distances for different X-ray energies from 2 to over 100 keV. Nickel lenses fabricated by electroforming using polymer templates can be applied for energies larger than 80 keV. The parabolic crossed lenses are used for 2D nano focusing of monochromatic beams. The quasi-parabolic crossed lenses with a submicron focus and a focus depth of the centimetre range can be used as an achromatic system. Mosaic truncated parabolic lenses with a focusing aperture up to 1 mm are made to increase the X-ray intensity in the focused spot.

Nazmov, Vladimir; Last, Arndt; Saile, Volker [Institut fuer Microstrukturtechnik, Forschungszentrum Karlsruhe GmbH, 76021 Karlsruhe (Germany); Karlsruhe University, 76131 Karlsruhe (Germany); Reznikova, Elena; Mohr, Jurgen [Institut fuer Microstrukturtechnik, Forschungszentrum Karlsruhe GmbH, 76021 Karlsruhe (Germany); Simon, Rolf [Institut fuer Synchrotronstrahlung, Forschungszentrum Karlsruhe GmbH, 76021 Karlsruhe (Germany); DiMichiel, Marco [European Synchrotron Radiation Facility, BP220, 38043, Grenoble (France)

2007-01-19T23:59:59.000Z

291

Indus-2 X-ray lithography beamline for X-ray optics and material science applications  

SciTech Connect (OSTI)

X-ray lithography is an ideal technique by which high aspect ratio and high spatial resolution micro/nano structures are fabricated using X-rays from synchrotron radiation source. The technique has been used for fabricating optics (X-ray, visible and infrared), sensors and actuators, fluidics and photonics. A beamline for X-ray lithography is operational on Indus-2. The beamline offers wide lithographic window from 1-40keV photon energy and wide beam for producing microstructures in polymers upto size ?100mm 100mm. X-ray exposures are possible in air, vacuum and He gas environment. The air based exposures enables the X-ray irradiation of resist for lithography and also irradiation of biological and liquid samples.

Dhamgaye, V. P., E-mail: vishal@rrcat.gov.in; Lodha, G. S., E-mail: vishal@rrcat.gov.in [Indus Synchrotrons Utilisation Division, Raja Ramanna Centre for Advanced Technology, Indore-452013 (India)

2014-04-24T23:59:59.000Z

292

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

E-Print Network [OSTI]

A neutron star low-mass X-ray binary is a binary stellar system with a neutron star and a low-mass companion star rotating around each other. In this system the neutron star accretes mass from the companion, and as this matter falls into the deep potential well of the neutron star, the gravitational potential energy is released primarily in the X-ray wavelengths. Such a source was first discovered in X-rays in 1962, and this discovery formally gave birth to the "X-ray astronomy". In the subsequent decades, our knowledge of these sources has increased enormously by the observations with several X-ray space missions. Here we give a brief overview of our current understanding of the X-ray observational aspects of these systems.

Sudip Bhattacharyya

2010-02-24T23:59:59.000Z

293

X-Ray Observations of Radio Galaxies  

E-Print Network [OSTI]

We review some of the ways that X-ray observations provide unique information on radio galaxies. Thermal bremsstrahlung X-ray emission provides detailed data on ambient densities and temperatures. These parameters in turn can be used for pressure balance calculations and can demonstrate how the ambient gas affects radio source structure. Additionally, many signatures of the interaction of radio jets and lobes with the hot gas are found in high resolution X-ray maps. Non-thermal X-ray emission from knots and hotspots of radio jets can give us constraints on the relativistic electron population for energies greater that that normally sampled in the radio (in the case of synchrotron emission) or can give us an independent estimate of the average magnetic field strength (if inverse Compton emission is the origin of the X-rays). From recent ROSAT HRI observations of 3C 390.3 and 3C 120, we show evidence that X-ray emission from knots and hotspots appears to be associated with regions of large gradients in the radio surface brightness; i.e. at the location of powerful shocks.

D. E. Harris

1998-04-20T23:59:59.000Z

294

Compton backscattered collimated x-ray source  

DOE Patents [OSTI]

A high-intensity, inexpensive and collimated x-ray source is disclosed for applications such as x-ray lithography is disclosed. An intense pulse from a high power laser, stored in a high-finesse resonator, repetitively collides nearly head-on with and Compton backscatters off a bunched electron beam, having relatively low energy and circulating in a compact storage ring. Both the laser and the electron beams are tightly focused and matched at the interaction region inside the optical resonator. The laser-electron interaction not only gives rise to x-rays at the desired wavelength, but also cools and stabilizes the electrons against intrabeam scattering and Coulomb repulsion with each other in the storage ring. This cooling provides a compact, intense bunch of electrons suitable for many applications. In particular, a sufficient amount of x-rays can be generated by this device to make it an excellent and flexible Compton backscattered x-ray (CBX) source for high throughput x-ray lithography and many other applications. 4 figs.

Ruth, R.D.; Huang, Z.

1998-10-20T23:59:59.000Z

295

Compton backscattered collmated X-ray source  

DOE Patents [OSTI]

A high-intensity, inexpensive and collimated x-ray source for applications such as x-ray lithography is disclosed. An intense pulse from a high power laser, stored in a high-finesse resonator, repetitively collides nearly head-on with and Compton backscatters off a bunched electron beam, having relatively low energy and circulating in a compact storage ring. Both the laser and the electron beams are tightly focused and matched at the interaction region inside the optical resonator. The laser-electron interaction not only gives rise to x-rays at the desired wavelength, but also cools and stabilizes the electrons against intrabeam scattering and Coulomb repulsion with each other in the storage ring. This cooling provides a compact, intense bunch of electrons suitable for many applications. In particular, a sufficient amount of x-rays can be generated by this device to make it an excellent and flexible Compton backscattered x-ray (CBX) source for high throughput x-ray lithography and many other applications.

Ruth, Ronald D. (Woodside, CA); Huang, Zhirong (Stanford, CA)

2000-01-01T23:59:59.000Z

296

Compton backscattered collimated x-ray source  

DOE Patents [OSTI]

A high-intensity, inexpensive and collimated x-ray source for applications such as x-ray lithography is disclosed. An intense pulse from a high power laser, stored in a high-finesse resonator, repetitively collides nearly head-on with and Compton backscatters off a bunched electron beam, having relatively low energy and circulating in a compact storage ring. Both the laser and the electron beams are tightly focused and matched at the interaction region inside the optical resonator. The laser-electron interaction not only gives rise to x-rays at the desired wavelength, but also cools and stabilizes the electrons against intrabeam scattering and Coulomb repulsion with each other in the storage ring. This cooling provides a compact, intense bunch of electrons suitable for many applications. In particular, a sufficient amount of x-rays can be generated by this device to make it an excellent and flexible Compton backscattered x-ray (CBX) source for high throughput x-ray lithography and many other applications.

Ruth, Ronald D. (Woodside, CA); Huang, Zhirong (Stanford, CA)

1998-01-01T23:59:59.000Z

297

MS 1603. 6 + 2600, an unusual X-ray selected binary system at high Galactic latitude  

SciTech Connect (OSTI)

The discovery of an eclipsing binary system at Galactic latitude 47 deg, found as a serendipitous X-ray source in the Einstein Extended Medium Sensitivity Survey, is described. The object has X-ray flux 1.1 x 10 to the -12th ergs/sq cm s (0.3-3.5 keV) and mean magnitude R = 19.4. An orbital period of 111 minutes is found. The problem discussed is whether the system has a white dwarf or neutron star primary, in the end preferring the neutron star primary model. If the system has either optical or X-ray luminosities typical of low mass X-ray binaries (LMXB), it must be at a very large distance (30-80 kpc). Blueshifted He I absorption is seen, indicating cool outflowing material, similar to that seen in the LMXB AC 211 in the globular cluster M15. 29 refs.

Morris, S.L.; Liebert, J.; Stocke, J.T.; Gioia, I.M.; Schild, R.E. (Observatories of the Carnegie Institution, Pasadena, CA (USA) Colorado Univ., Boulder (USA) Harvard-Smithsonian Center for Astrophysics, Cambridge, MA (USA))

1990-12-01T23:59:59.000Z

298

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

299

Transient x-ray diffraction and its application to materials science and x-ray optics  

SciTech Connect (OSTI)

Time resolved x-ray diffraction and scattering have been applied to the measurement of a wide variety of physical phenomena from chemical reactions to shock wave physics. Interest in this method has heightened in recent years with the advent of versatile, high power, pulsed x-ray sources utilizing laser plasmas, electron beams and other methods. In this article, we will describe some of the fundamentals involved in time resolved x-ray diffraction, review some of the history of its development, and describe some recent progress in the field. In this article we will emphasize the use of laser-plasmas as the x-ray source for transient diffraction.

Hauer, A.A.; Kopp, R.; Cobble, J.; Kyrala, G.; Springer, R. [and others

1997-12-01T23:59:59.000Z

300

RADIO AND X-RAY OBSERVATIONS OF SN 2006jd: ANOTHER STRONGLY INTERACTING TYPE IIn SUPERNOVA  

SciTech Connect (OSTI)

We report four years of radio and X-ray monitoring of the Type IIn supernova SN 2006jd at radio wavelengths with the Very Large Array, Giant Metrewave Radio Telescope, and Expanded Very Large Array; at X-ray wavelengths with Chandra, XMM-Newton, and Swift-XRT. We assume that the radio and X-ray emitting particles are produced by shock interaction with a dense circumstellar medium. The radio emission shows an initial rise that can be attributed to free-free absorption by cool gas mixed into the nonthermal emitting region; external free-free absorption is disfavored because of the shape of the rising light curves and the low gas column density inferred along the line of sight to the emission region. The X-ray luminosity implies a preshock circumstellar density {approx}10{sup 6} cm{sup -3} at a radius r {approx} 2 Multiplication-Sign 10{sup 16} cm, but the column density inferred from the photoabsorption of X-rays along the line of sight suggests a significantly lower density. The implication may be an asymmetry in the interaction. The X-ray spectrum shows Fe line emission at 6.9 keV that is stronger than is expected for the conditions in the X-ray emitting gas. We suggest that cool gas mixed into the hot gas plays a role in the line emission. Our radio and X-ray data both suggest the density profile is flatter than r{sup -2} because of the slow evolution of the unabsorbed emission.

Chandra, Poonam [Department of Physics, Royal Military College of Canada, Kingston, ON K7K 7B4 (Canada); Chevalier, Roger A.; Irwin, Christopher M. [Department of Astronomy, University of Virginia, P.O. Box 400325, Charlottesville, VA 22904-4325 (United States); Chugai, Nikolai [Institute of Astronomy of Russian Academy of Sciences, Pyatnitskaya Street 48, 109017 Moscow (Russian Federation); Fransson, Claes [Department of Astronomy, Stockholm University, AlbaNova, SE-106 91 Stockholm (Sweden); Soderberg, Alicia M. [Smithsonian Astrophysical Observatory, 60 Garden Street, MS-20, Cambridge, MA 02138 (United States); Chakraborti, Sayan [Department of Astronomy and Astrophysics, Tata Institute of Fundamental Research, 1 Homi Bhabha Road, Colaba, Mumbai 400005 (India); Immler, Stefan, E-mail: Poonam.Chandra@rmc.ca [Astrophysics Science Division, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)

2012-08-20T23:59:59.000Z

Note: This page contains sample records for the topic "x-ray absorption fine" 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 XMM large scale structure survey: optical vs. X-ray classifications of active galactic nuclei and the unified scheme  

E-Print Network [OSTI]

Our goal is to characterize AGN populations by comparing their X-ray and optical classifications. We present a sample of 99 spectroscopically identified X-ray point sources in the XMM-LSS survey which are significantly detected in the [2-10] keV band, and with more than 80 counts. We performed an X-ray spectral analysis for all of these 99 X-ray sources. Introducing the fourfold point correlation coefficient, we find only a mild correlation between the X-ray and the optical classifications, as up to 30% of the sources have differing X-ray and optical classifications: on one hand, 10% of the type 1 sources present broad emission lines in their optical spectra and strong absorption in the X-rays. These objects are highly luminous AGN lying at high redshift and thus dilution effects are totally ruled out, their discrepant nature being an intrinsic property. Their X-ray luminosities and redshifts distributions are consistent with those of the unabsorbed X-ray sources with broad emission lines. On the other hand, ...

Garcet, O; Gosset, E; Sprimont, P G; Surdej, J; Borkowski, V; Tajer, M; Pacaud, F; Pierre, M; Chiappetti, L; MacCagni, D; Page, M J; Carrera, F J; Tedds, J A; Mateos, S; Krumpe, M; Contini, T; Corral, A; Ebrero, J; Gavignaud, I; Schwope, A; Le Fvre, O; Polletta, M; Rosen, S; Lonsdale, C; Watson, M; Borczyk, W; Visnen, P

2007-01-01T23:59:59.000Z

302

Oscillations During Thermonuclear X-ray Bursts  

E-Print Network [OSTI]

High amplitude, nearly coherent X-ray brightness oscillations during thermonuclear X-ray bursts were discovered with the Rossi X-ray Timing Explorer (RXTE) in early 1996. Spectral and timing evidence strongly supports the conclusion that these oscillations are caused by rotational modulation of the burst emission and that they reveal the spin frequency of neutron stars in low mass X-ray binaries, a long sought goal of X-ray astronomy. Studies carried out over the past year have led to the discovery of burst oscillations in four new sources, bringing to ten the number with confirmed burst oscillations. I review the status of our knowledge of these oscillations and indicate how they can be used to probe the physics of neutron stars. For a few burst oscillation sources it has been proposed that the strongest and most ubiquitous frequency is actually the first overtone of the spin frequency and hence that two nearly antipodal hot spots are present on the neutron star. This inference has important implications for both the physics of thermonuclear burning as well as the mass- radius relation for neutron stars, so its confirmation is crucial. I discuss recent attempts to confirm this hypothesis for 4U 1636-53, the source for which a signal at the putative fundamental (290 Hz) has been claimed.

Tod E. Strohmayer

2001-01-01T23:59:59.000Z

303

X-ray Pinhole Camera Measurements  

SciTech Connect (OSTI)

The development of the rod pinch diode [1] has led to high-resolution radiography for dynamic events such as explosive tests. Rod pinch diodes use a small diameter anode rod, which extends through the aperture of a cathode plate. Electrons borne off the aperture surface can self-insulate and pinch onto the tip of the rod, creating an intense, small x-ray source (Primary Pinch). This source has been utilized as the main diagnostic on numerous experiments that include high-value, single-shot events. In such applications there is an emphasis on machine reliability, x-ray reproducibility, and x-ray quality [2]. In tests with the baseline rod pinch diode, we have observed that an additional pinch (Secondary Pinch) occurs at the interface near the anode rod and the rod holder. This suggests that stray electrons exist that are not associated with the Primary Pinch. In this paper we present measurements on both pinches using an x-ray pinhole camera. The camera is placed downstream of the Primary Pinch at an angle of 60 with respect to the diode centerline. This diagnostic will be employed to diagnose x-ray reproducibility and quality. In addition, we will investigate the performance of hybrid diodes relating to the formation of the Primary and Secondary Pinches.

Nelson, D. S. [NSTec; Berninger, M. J. [NSTec; Flores, P. A. [NSTec; Good, D. E. [NSTec; Henderson, D. J. [NSTec; Hogge, K. W. [NSTec; Huber, S. R. [NSTec; Lutz, S. S. [NSTec; Mitchell, S. E. [NSTec; Howe, R. A. [NSTec; Mitton, C. V. [NSTec; Molina, I. [NSTec; Bozman, D. R. [SNL; Cordova, S. R. [SNL; Mitchell, D. R. [SNL; Oliver, B. V. [SNL; Ormond, E. C. [SNL

2013-07-01T23:59:59.000Z

304

Nonlinear X-ray Compton Scattering  

E-Print Network [OSTI]

X-ray scattering is a weak linear probe of matter. It is primarily sensitive to the position of electrons and their momentum distribution. Elastic X-ray scattering forms the basis of atomic structural determination while inelastic Compton scattering is often used as a spectroscopic probe of both single-particle excitations and collective modes. X-ray free-electron lasers (XFELs) are unique tools for studying matter on its natural time and length scales due to their bright and coherent ultrashort pulses. However, in the focus of an XFEL the assumption of a weak linear probe breaks down, and nonlinear light-matter interactions can become ubiquitous. The field can be sufficiently high that even non-resonant multiphoton interactions at hard X-rays wavelengths become relevant. Here we report the observation of one of the most fundamental nonlinear X-ray-matter interactions, the simultaneous Compton scattering of two identical photons producing a single photon at nearly twice the photon energy. We measure scattered...

Fuchs, Matthias; Chen, Jian; Ghimire, Shambhu; Shwartz, Sharon; Kozina, Michael; Jiang, Mason; Henighan, Thomas; Bray, Crystal; Ndabashimiye, Georges; Bucksbaum, P H; Feng, Yiping; Herrmann, Sven; Carini, Gabriella; Pines, Jack; Hart, Philip; Kenney, Christopher; Guillet, Serge; Boutet, Sebastien; Williams, Garth; Messerschmidt, Marc; Seibert, Marvin; Moeller, Stefan; Hastings, Jerome B; Reis, David A

2015-01-01T23:59:59.000Z

305

Ultrafast X-Ray Coherent Control  

SciTech Connect (OSTI)

This main purpose of this grant was to develop the nascent #12;eld of ultrafast x-ray science using accelerator-based sources, and originally developed from an idea that a laser could modulate the di#11;racting properties of a x-ray di#11;racting crystal on a fast enough time scale to switch out in time a shorter slice from the already short x-ray pulses from a synchrotron. The research was carried out primarily at the Advanced Photon Source (APS) sector 7 at Argonne National Laboratory and the Sub-Picosecond Pulse Source (SPPS) at SLAC; in anticipation of the Linac Coherent Light Source (LCLS) x-ray free electron laser that became operational in 2009 at SLAC (all National User Facilities operated by BES). The research centered on the generation, control and measurement of atomic-scale dynamics in atomic, molecular optical and condensed matter systems with temporal and spatial resolution . It helped develop the ultrafast physics, techniques and scienti#12;c case for using the unprecedented characteristics of the LCLS. The project has been very successful with results have been disseminated widely and in top journals, have been well cited in the #12;eld, and have laid the foundation for many experiments being performed on the LCLS, the world's #12;rst hard x-ray free electron laser.

Reis, David

2009-05-01T23:59:59.000Z

306

Oscillations During Thermonuclear X-ray Bursts  

E-Print Network [OSTI]

High amplitude, nearly coherent X-ray brightness oscillations during thermonuclear X-ray bursts were discovered with the Rossi X-ray Timing Explorer (RXTE) in early 1996. Spectral and timing evidence strongly supports the conclusion that these oscillations are caused by rotational modulation of the burst emission and that they reveal the spin frequency of neutron stars in low mass X-ray binaries, a long sought goal of X-ray astronomy. Studies carried out over the past year have led to the discovery of burst oscillations in four new sources, bringing to ten the number with confirmed burst oscillations. I review the status of our knowledge of these oscillations and indicate how they can be used to probe the physics of neutron stars. For a few burst oscillation sources it has been proposed that the strongest and most ubiquitous frequency is actually the first overtone of the spin frequency and hence that two nearly antipodal hot spots are present on the neutron star. This inference has important implications for both the physics of thermonuclear burning as well as the mass - radius relation for neutron stars, so its confirmation is crucial. I discuss recent attempts to confirm this hypothesis for 4U 1636-53, the source for which a signal at the putative fundamental (290 Hz) has been claimed.

Tod E. Strohmayer

2001-01-12T23:59:59.000Z

307

X-ray lithography using holographic images  

DOE Patents [OSTI]

Methods for forming X-ray images having 0.25 .mu.m minimum line widths on X-ray sensitive material are presented. A holgraphic image of a desired circuit pattern is projected onto a wafer or other image-receiving substrate to allow recording of the desired image in photoresist material. In one embodiment, the method uses on-axis transmission and provides a high flux X-ray source having modest monochromaticity and coherence requirements. A layer of light-sensitive photoresist material on a wafer with a selected surface is provided to receive the image(s). The hologram has variable optical thickness and variable associated optical phase angle and amplitude attenuation for transmission of the X-rays. A second embodiment uses off-axis holography. The wafer receives the holographic image by grazing incidence reflection from a hologram printed on a flat metal or other highly reflecting surface or substrate. In this second embodiment, an X-ray beam with a high degree of monochromaticity and spatial coherence is required.

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

1997-01-01T23:59:59.000Z

308

Reflection soft X-ray microscope and method  

DOE Patents [OSTI]

A reflection soft X-ray microscope is provided by generating soft X-ray beams, condensing the X-ray beams to strike a surface of an object at a predetermined angle, and focusing the X-ray beams reflected from the surface onto a detector, for recording an image of the surface or near surface features of the object under observation.

Suckewer, Szymon (Princeton, NJ); Skinner, Charles H. (Lawrenceville, NJ); Rosser, Roy (Princeton, NJ)

1993-01-01T23:59:59.000Z

309

Differential phase contrast X-ray imaging system and components  

DOE Patents [OSTI]

A differential phase contrast X-ray imaging system includes an X-ray illumination system, a beam splitter arranged in an optical path of the X-ray illumination system, and a detection system arranged in an optical path to detect X-rays after passing through the beam splitter.

Stutman, Daniel; Finkenthal, Michael

2014-07-01T23:59:59.000Z

310

X-RAY SPECTROMETRY X-Ray Spectrom. 2007; 36: 336342  

E-Print Network [OSTI]

, Chicago, IL 60637, USA 3 Cornell High Energy Synchrotron Source and School of Applied and EngineeringX-RAY SPECTROMETRY X-Ray Spectrom. 2007; 36: 336­342 Published online in Wiley InterScience (www to establish a breakthrough in high-resolution, simultaneous area mapping of multiple trace elements

Limburg, Karin E.

311

In Operando X-ray Diffraction and Transmission X-ray Microscopy of Lithium Sulfur Batteries  

E-Print Network [OSTI]

In Operando X-ray Diffraction and Transmission X-ray Microscopy of Lithium Sulfur Batteries Johanna Information ABSTRACT: Rechargeable lithium-sulfur (Li-S) batteries hold great potential for high of these batteries for commercial use. The two primary obstacles are the solubility of long chain lithium

Cui, Yi

312

X-Ray Data from the X-Ray Data Booklet Online  

DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

The original X-Ray Data Booklet, published in 1985, became a classic reference source. The online version has been significantly revised and updated to reflect today's science. Hundreds of pages of authoritative data provide the x-ray properties of elements, information on synchrotron radiation, scattering processes, optics and detectors, and other related calculations, formulas, and data tables.

Thompson, Albert C.; Attwood, David T.; Gullikson, Eric M.; Howells, Malcolm R.; Kortright, Jeffrey B.; Robinson, Arthur L.; Underwood, James H.; Kim, Kwang-Je; Kirz, Janos; Lindau, Ingolf; Pianetta, Piero; Winick, Herman; Williams, Gwyn P.; Scofield, James H.

313

Predicted X-ray backgrounds for the International X-ray Observatory  

E-Print Network [OSTI]

The background that will be observed by IXO's X-ray detectors naturally separates into two components: (1) a Cosmic X-ray Background (CXB), primarily due to unresolved point sources at high energies (E>2 keV), along with ...

Bautz, Marshall W.

314

X-ray reflectivity and surface roughness  

SciTech Connect (OSTI)

Since the advent of high brightness synchrotron radiation sources there has been a phenomenal growth in the use of x-rays as a probe of surface structure. The technique of x-ray reflectivity is particularly relevant to electrochemists since it is capable of probing the structure normal to an electrode surface in situ. In this paper the theoretical framework for x-ray reflectivity is reviewed and the results from previous non-electrochemistry measurements are summarized. These measurements are from the liquid/air interface (CCl/sub 4/), the metal crystal vacuum interface (Au(100)), and from the liquid/solid interface(liquid crystal/silicon). 34 refs., 5 figs.

Ocko, B.M.

1988-01-01T23:59:59.000Z

315

X-ray variability in M87  

E-Print Network [OSTI]

We present the evidence for X-ray variability from the core and from knot A in the M87 jet based on data from two observations with the Einstein Observatory High Resolution Imager (HRI) and three observations with the ROSAT HRI. The core intensity showed a 16% increase in 17 months ('79-'80); a 12% increase in the 3 years '92 to '95; and a 17% drop in the last half of 1995. The intensity of knot A appears to have decreased by 16% between 92Jun and 95Dec. Although the core variability is consistent with general expectations for AGN nuclei, the changes in knot A provide constraints on the x-ray emission process and geometry. Thus we predict that the x-ray morphology of knot A will differ significantly from the radio and optical structure.

D. E. Harris; J. A. Biretta; W. Junor

1996-12-05T23:59:59.000Z

316

Combined microstructure x-ray optics  

SciTech Connect (OSTI)

Multilayers are man-made microstructures which vary in depth and are now of sufficient quality to be used as x-ray, soft x-ray and extreme ultraviolet optics. Gratings are man-made in plane microstructures which have been used as optic elements for most of this century. Joining of these two optical microstructures to form combined microstructure optical microstructures to form combined microstructure optical elements has the potential for greatly enhancing both the throughput and the resolution attainable in these spectral ranges. The characteristics of these new optic elements will be presented and compared to experiment with emphasis on the unique properties of these combined microstructures. These results reported are general in nature and not limited to the soft x-ray or extreme ultraviolet spectral domains and also apply to neutrons. 19 refs., 7 figs., 4 tabs.

Barbee, T.W. Jr.

1989-02-01T23:59:59.000Z

317

The X-ray/submillimetre link  

E-Print Network [OSTI]

It is widely believed that most of the cosmic X-ray background (XRB) is produced by a vast, hitherto undetected population of obscured AGN. Deep X-ray surveys with Chandra and XMM will soon test this hypothesis. Similarly, recent sub-mm surveys with SCUBA have revealed an analogous population of exceptionally luminous, dust-enshrouded {\\em star-forming} galaxies at high redshift. There is now growing evidence for an intimate link between these obscured populations. There are currently large uncertainties in the models, but several independent arguments lead to the conclusion that a significant fraction of the SCUBA sources ($10-30% $) will contain quasars. Recent observational studies of SCUBA survey sources appear to confirm these predictions, although the relative roles of AGN and star-forming activity in heating the dust are unclear. Forthcoming surveys combining X-ray and sub-mm observations will provide a very powerful tool for disentangling these processes.

O. Almaini

2000-01-07T23:59:59.000Z

318

X-ray atlas of rheumatic diseases  

SciTech Connect (OSTI)

This atlas comprises instructive X-rays of the various inflammatory rheumatic joint diseases in all stages at the extremities and the spinal column. In addition, the complex pattern of the wide range of arthroses, also known as degenerative rheumatic disease is included. Besides the instructive pointers to X-ray diagnosis, the book is also a guide to differential diagnosis. Hence, this book is actually an X-ray atlas of joint diseases in general. Selected Contents: Introduction: What Does ''Rheumatism'' Actually Mean./Radiographic Methodology in Rheumatic Diseases of the Locomotor System/The Mosaic of Arthritis/Adult Rheumatoid Arthritis/Seronegative Spondylarthritis/Classic Collagen Diseases/Enthesiopathies/Gout-Pseudogout

Dihlmann, W.

1986-01-01T23:59:59.000Z

319

X-ray focal spot locating apparatus and method  

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, Hubert W. (Cedar Crest, NM)

1985-07-30T23:59:59.000Z

320

Anomalous X-ray Diffraction Studies for Photovoltaic Applications  

SciTech Connect (OSTI)

Anomalous X-ray Diffraction (AXRD) has become a useful technique in characterizing bulk and nanomaterials as it provides specific information about the crystal structure of materials. In this project we present the results of AXRD applied to materials for photovoltaic applications: ZnO loaded with Ga and ZnCo{sub 2}O{sub 4} spinel. The X-ray diffraction data collected for various energies were plotted in Origin software. The peaks were fitted using different functions including Pseudo Voigt, Gaussian, and Lorentzian. This fitting provided the integrated intensity data (peaks area values), which when plotted as a function of X-ray energies determined the material structure. For the first analyzed sample, Ga was not incorporated into the ZnO crystal structure. For the ZnCo{sub 2}O{sub 4} spinel Co was found in one or both tetrahedral and octahedral sites. The use of anomalous X-ray diffraction (AXRD) provides element and site specific information for the crystal structure of a material. This technique lets us correlate the structure to the electronic properties of the materials as it allows us to probe precise locations of cations in the spinel structure. What makes it possible is that in AXRD the diffraction pattern is measured at a number of energies near an X-ray absorption edge of an element of interest. The atomic scattering strength of an element varies near its absorption edge and hence the total intensity of the diffraction peak changes by changing the X-ray energy. Thus AXRD provides element specific structural information. This method can be applied to both crystalline and liquid materials. One of the advantages of AXRD in crystallography experiments is its sensitivity to neighboring elements in the periodic tables. This method is also sensitive to specific crystallographic phases and to a specific site in a phase. The main use of AXRD in this study is for transparent conductors (TCs) analysis. TCs are considered to be important materials because of their efficiency and low risk of environmental pollution. These materials are important to solar cells as a result of their remarkable combination of optical and electrical properties, including high electrical conductivity and high optical transparency in the spectrum of visible light. TCs provide a transparent window, which allows sunlight to pass through while also allowing electricity to conduct out of the cell. Spinel materials have the chemical form AB{sub 2}O{sub 4}, and are made of a face-centered cubic (FCC) lattice of oxygen anions and cations in specific interstitial sites. A normal spinel has all A cations on tetrahedral sites and B cations on octahedral sites. In contrast; an inverse spinel has the A and half of the B cations on octahedral sites and the other half of the B cations on tetrahedral sites; a mixed spinel lies between. In the spinel structure, 8 of 64 possible tetrahedral sites and 16 of 32 possible octahedral sites are filled. Normal spinels have particularly high conduction as the linear octahedral chains of B cations likely serve as conduction paths. In this paper we present how the data obtained with AXRD is used to analyze TCs properties as they apply to photovoltaic applications. One of the materials used for this analysis is zinc oxide. It has been loaded with 5% and 10% of Ga, which has an absorption edge of 10367 eV. The peak (100) was measured for the zinc oxide loaded with 10% Ga. In the case of 5% Ga, we measured peaks (100) and (101). With the information provided by the AXRD we can identify if Ga is being incorporated in the ZnO crystal structure. The analysis of 311 plane in the ZnCo{sub 2}O{sub 4} spinel shows if Co is in tetrahedral or octahedral site.

Not Available

2011-06-22T23:59:59.000Z

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321

Brighter Screens for Nondestructive Digital X-ray Radiography  

SciTech Connect (OSTI)

Fine resolution, bright X-ray screens are needed for digital radiography and material characterization at the Y-12 National Security Complex (Y-12). Current technology is simply not adequate for transferring high-energy X-ray images to visible light for demanding digital applications. Low energy radiography and especially emerging tomographic technologies are severely hampered for Y-12 nondestructive evaluation (NDE) applications by dim screens with poor resolution. Also, the development of more advanced materials characterization techniques, such as electron backscatter diffraction (EBSD), is driven by a design agency desire for tighter specifications and more uniform materials. Brighter screens would allow us to probe materials on a finer scale, leading to a better understanding of material behavior. A number of X-ray screen materials were studied that would be suitable for direct replacement in existing digital imaging systems. Spectroscopic evaluations were first made for a several candidates and indicated that lutetium orthosilicate (LSO) would be a promising candidate for MeV images. A relative comparison of brightness at various energies was then completed which showed that cesium iodide (CsI) could increase brightness by over an order of magnitude. Since image quality is also important for better screens, the resolving capabilities of candidate materials were measured. Resolution measurements were completed at X-ray peak energies up to 420KeV with magnified optical imaging systems, and indicated that LSO and Industrial Quality Incorporated glass (IQI) exhibited higher resolution than the CsI screen. The results give a choice of materials that can be tailored to the particular test under consideration. If high-speed images are necessary and some resolution can be sacrificed, the CsI screen will be a good choice. The screen can be replaced by an IQI or LSO unit if higher resolution is needed later, for instance to focus in on a region of interest. A number of significant findings were obtained from this study. Most important of the findings was that materials are commercially available that are much brighter than screens currently in use. This finding meets the original objective of the project. Two objectives of the study; however, were not met. We hoped to evaluate a 'quantum dot' (nanometer-sized particles of semiconductor material) wavelength conversion screen, but the manufacturer ceased production of the screen shortly before the project was started. The dot screen could be efficient in converting ultraviolet light to visible light which would have proved important for utilizing a Cherenkov screen. Since this was a very new, cutting-edge technology, an alternative supplier was not found during the study. Also, high-energy testing of a Cherenkov light screen was not performed due to difficulties in obtaining appropriate approvals for locating test equipment in the high-energy X-ray vault at Y-12. The test is still important, and is being pursued through follow-on funding sources. Although many film shots will be eliminated by the availability of high quality digital images, the largest potential gains result from the availability of clearer images that show fine detail in the parts under analysis. Digital radiographic data also offers the possibility of easily sharing data with other sites. This could prove invaluable when critical material, placement, assembly, or quality issues are pressing. Also, increased throughput in the NDE facility allows statistically significant numbers of units to be analyzed. Digital technologies may in fact be needed just to meet minimum requirements of future demands. Increased brightness screens allow for such innovations as 3-D tomographic images to be acquired in a reasonable time. Much of the skill required to interpret 'flattened' X-ray images is not needed to maneuver around the reconstructed tomogram. This study showed that several commercially available materials are much brighter than screens currently in use. The study also showed that materials othe

Miller, Jr., A. C.; Bell, Z. W.; Carpenter, D. A.

2003-09-15T23:59:59.000Z

322

Energy resolved X-ray grating interferometry  

SciTech Connect (OSTI)

Although compatible with polychromatic radiation, the sensitivity in X-ray phase contrast imaging with a grating interferometer is strongly dependent on the X-ray spectrum. We used an energy resolving detector to quantitatively investigate the dependency of the noise from the spectral bandwidth and to consequently optimize the system-by selecting the best energy band matching the experimental conditions-with respect to sensitivity maximization and, eventually, dose. Further, since theoretical calculations of the spectrum are usually limited due to non-ideal conditions, an energy resolving detector accurately quantifies the spectral changes induced by the interferometer including flux reduction and beam hardening.

Thuering, T.; Stampanoni, M. [Swiss Light Source, Paul Scherrer Institut, Villigen PSI (Switzerland) [Swiss Light Source, Paul Scherrer Institut, Villigen PSI (Switzerland); Institute for Biomedical Engineering, Swiss Federal Institute of Technology, Zurich (Switzerland); Barber, W. C.; Iwanczyk, J. S. [DxRay, Inc., Northridge, California 91324 (United States)] [DxRay, Inc., Northridge, California 91324 (United States); Seo, Y.; Alhassen, F. [UCSF Physics Research Laboratory, Department of Radiology and Biomedical Imaging, University of California, San Francisco, California 94143 (United States)] [UCSF Physics Research Laboratory, Department of Radiology and Biomedical Imaging, University of California, San Francisco, California 94143 (United States)

2013-05-13T23:59:59.000Z

323

Radiobiological studies using gamma and x rays.  

SciTech Connect (OSTI)

There are approximately 500 self-shielded research irradiators used in various facilities throughout the U.S. These facilities use radioactive sources containing either 137Cs or 60Co for a variety of biological investigations. A report from the National Academy of Sciences[1] described the issues with security of particular radiation sources and the desire for their replacement. The participants in this effort prepared two peer-reviewed publications to document the results of radiobiological studies performed using photons from 320-kV x rays and 137Cs on cell cultures and mice. The effectiveness of X rays was shown to vary with cell type.

Potter, Charles Augustus; Longley, Susan W.; Scott, Bobby R. [Lovelace Respiratory Research Institute, Albuquerque, NM; Lin, Yong [Lovelace Respiratory Research Institute, Albuquerque, NM; Wilder, Julie [Lovelace Respiratory Research Institute, Albuquerque, NM; Hutt, Julie A. [Lovelace Respiratory Research Institute, Albuquerque, NM; Padilla, Mabel T. [Lovelace Respiratory Research Institute, Albuquerque, NM; Gott, Katherine M. [Lovelace Respiratory Research Institute, Albuquerque, NM

2013-02-01T23:59:59.000Z

324

Time-resolved x-ray diagnostics  

SciTech Connect (OSTI)

Techniques for time-resolved x-ray diagnostics will be reviewed with emphasis on systems utilizing x-ray diodes or scintillators. System design concerns for high-bandwidth (> 1 GHz) diagnostics will be emphasized. The limitations of a coaxial cable system and a technique for equalizing to improve bandwidth of such a system will be reviewed. Characteristics of new multi-GHz amplifiers will be presented. An example of a complete operational system on the Los Alamos Helios laser will be presented which has a bandwidth near 3 GHz over 38 m of coax. The system includes the cable, an amplifier, an oscilloscope, and a digital camera readout.

Lyons, P.B.

1981-01-01T23:59:59.000Z

325

Lensless X-Ray Imaging in Reflection  

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 MayAtmospheric Optical Depth7-1D: VegetationEquipment Surfaces and Interfaces Sample6, 2011 LawrenceE C H NLensless X-RayLensless X-Ray

326

X-Ray Nanoimaging: Instruments and Methods  

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 Imaging ofX-Ray

327

X-ray Computed Tomography | EMSL  

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 ImagingfeedX-ray

328

The XMM large scale structure survey: optical vs. X-ray classifications of active galactic nuclei and the unified scheme  

E-Print Network [OSTI]

Our goal is to characterize AGN populations by comparing their X-ray and optical classifications. We present a sample of 99 spectroscopically identified X-ray point sources in the XMM-LSS survey which are significantly detected in the [2-10] keV band, and with more than 80 counts. We performed an X-ray spectral analysis for all of these 99 X-ray sources. Introducing the fourfold point correlation coefficient, we find only a mild correlation between the X-ray and the optical classifications, as up to 30% of the sources have differing X-ray and optical classifications: on one hand, 10% of the type 1 sources present broad emission lines in their optical spectra and strong absorption in the X-rays. These objects are highly luminous AGN lying at high redshift and thus dilution effects are totally ruled out, their discrepant nature being an intrinsic property. Their X-ray luminosities and redshifts distributions are consistent with those of the unabsorbed X-ray sources with broad emission lines. On the other hand, 25/32 are moderate luminosity AGN, which are both unabsorbed in the X-rays and only present narrow emission lines in their optical spectra. The majority of them have an optical spectrum which is representative of the host galaxy. We finally infer that dilution of the AGN by the host galaxy seems to account for their nature. 5/25 have been defined as Seyfert 2. In conclusion, most of these 32 discrepant cases can be accounted for by the standard AGN unified scheme, as its predictions are not met for only 12% of the 99 X-ray sources. ABRIDGED

O. Garcet; P. Gandhi; E. Gosset; P. G. Sprimont; J. Surdej; V. Borkowski; M. Tajer; F. Pacaud; M. Pierre; L. Chiappetti; D. Maccagni; M. J. Page; F. J. Carrera; J. A. Tedds; S. Mateos; M. Krumpe; T. Contini; A. Corral; J. Ebrero; I. Gavignaud; A. Schwope; O. Le Fevre; M. Polletta; S. Rosen; C. Lonsdale; M. Watson; W. Borczyk; P. Vaisanen

2007-09-13T23:59:59.000Z

329

Titanium and germanium lined hohlraums and halfraums as multi-keV x-ray radiators  

SciTech Connect (OSTI)

As multi-keV x-ray radiators, hohlraums and halfraums with inner walls coated with metallic materials (called liner) have been tested for the first time with laser as the energy drive. For titanium, conversion efficiencies (CEs) are up to {approx}14% for emission into 4{pi}, integrating between 4.6 and 6.5 keV when a large diameter hohlraum is used. Germanium CE is {approx}0.8% into 4{pi} between 9 and 13 keV. The highest CEs have been obtained with a 1 ns squared pulse and phase plates giving laser absorption near 99%. These high CEs are due to long-lasting, good plasma conditions for multi-keV x-ray production maintained by plasma confinement inside the plastic cylinder and plasma collision leading to a burst of x rays at a time that depends on target size. As photon emitters at 4.7 keV, titanium-lined hohlraums are the most efficient solid targets and data are close to CEs for gas targets, which are considered as the upper limit for x-ray yields since their low density allows good laser absorption and low kinetics losses. As 10.3 keV x-ray emitters, exploded germanium foils give best results one order of magnitude more efficient than thick targets; doped aerogels and lined hohlraums give similar yields, about three times lower than those from exploded foils.

Girard, F.; Primout, M.; Villette, B.; Stemmler, Ph.; Jacquet, L.; Babonneau, D. [CEA, DAM, DIF, F-91297 Arpajon (France); Fournier, K. B. [Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94550 (United States)

2009-05-15T23:59:59.000Z

330

Small Angle X-Ray Scattering Detector  

DOE Patents [OSTI]

A detector for time-resolved small-angle x-ray scattering includes a nearly constant diameter, evacuated linear tube having an end plate detector with a first fluorescent screen and concentric rings of first fiber optic bundles for low angle scattering detection and an annular detector having a second fluorescent screen and second fiber optic bundles concentrically disposed about the tube for higher angle scattering detection. With the scattering source, i.e., the specimen under investigation, located outside of the evacuated tube on the tube's longitudinal axis, scattered x-rays are detected by the fiber optic bundles, to each of which is coupled a respective photodetector, to provide a measurement resolution, i.e., dq/q, where q is the momentum transferred from an incident x-ray to an x-ray scattering specimen, of 2% over two (2) orders of magnitude in reciprocal space, i.e., q.sub.max /q.sub.min.congruent.100.

Hessler, Jan P. (Downers Grove, IL)

2004-06-15T23:59:59.000Z

331

SLAC All Access: X-ray Microscope  

ScienceCinema (OSTI)

SLAC physicists Johanna Nelson and Yijin Liu give a brief overview of the X-ray microscope at the Stanford Synchrotron Radiation Lightsource (SSRL) that is helping improve rechargeable-battery technology by letting researchers peek into the inner workings of batteries as they operate.

Nelson, Johanna; Liu, Yijin

2014-06-13T23:59:59.000Z

332

Multiple wavelength X-ray monochromators  

DOE Patents [OSTI]

An improved apparatus and method is provided for separating input x-ray radiation containing first and second x-ray wavelengths into spatially separate first and second output radiation which contain the first and second x-ray wavelengths, respectively. The apparatus includes a crystalline diffractor which includes a first set of parallel crystal planes, where each of the planes is spaced a predetermined first distance from one another. The crystalline diffractor also includes a second set of parallel crystal planes inclined at an angle with respect to the first set of crystal planes where each of the planes of the second set of parallel crystal planes is spaced a predetermined second distance from one another. In one embodiment, the crystalline diffractor is comprised of a single crystal. In a second embodiment, the crystalline diffractor is comprised of a stack of two crystals. In a third embodiment, the crystalline diffractor includes a single crystal that is bent for focusing the separate first and second output x-ray radiation wavelengths into separate focal points. 3 figs.

Steinmeyer, P.A.

1992-11-17T23:59:59.000Z

333

Catalog of supersoft X-ray sources  

E-Print Network [OSTI]

This catalog comprises an up-to-date (December 1999) list of luminous (>10^36 erg/s), binary supersoft X-ray sources. This electronic version (including the accompannying Web-pages) supersedes the printed version of Greiner (1996).

J. Greiner

2000-05-11T23:59:59.000Z

334

SPECTRAL PROPERTIES OF X-RAY BINARIES IN CENTAURUS A  

SciTech Connect (OSTI)

We present a spectral investigation of X-ray binaries (XBs) in NGC 5128 (Cen A), using six 100 ks Chandra observations taken over two months in 2007. We divide our sample into thermally and non-thermally dominated states based on the behavior of the fitted absorption column N{sub H}, and present the spectral parameters of sources with L{sub x} {approx}> 2 Multiplication-Sign 10{sup 37} erg s{sup -1}. The majority of sources are consistent with being neutron star low-mass X-ray binaries (NS LMXBs) and we identify three transient black hole (BH) LMXB candidates coincident with the dust lane, which is the remnant of a small late-type galaxy. Our results also provide tentative support for the apparent 'gap' in the mass distribution of compact objects between {approx}2-5 M{sub Sun }. We propose that BH LMXBs are preferentially found in the dust lane, and suggest this is because of the younger stellar population. The majority ({approx}70%-80%) of potential Roche lobe filling donors in the Cen A halo are {approx}> 12 Gyr old, while BH LMXBs require donors {approx}> 1 M{sub Sun} to produce the observed peak luminosities. This requirement for more massive donors may also explain recent results that claim a steepening of the X-ray luminosity function with age at L{sub x} {>=} 5 Multiplication-Sign 10{sup 38} erg s{sup -1} for the XB population of early-type galaxies; for older stellar populations, there are fewer stars {approx}> 1 M{sub Sun }, which are required to form the more luminous sources.

Burke, Mark J.; Raychaudhury, Somak [School of Physics and Astronomy, University of Birmingham, Edgbaston, Birmingham B15 2TT (United Kingdom)] [School of Physics and Astronomy, University of Birmingham, Edgbaston, Birmingham B15 2TT (United Kingdom); Kraft, Ralph P.; Forman, William R.; Jones, Christine; Murray, Stephen S.; Birkinshaw, Mark; Evans, Daniel A.; Jordan, Andres [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)] [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Maccarone, Thomas J.; Croston, Judith H. [School of Physics and Astronomy, University of Southampton, Southampton SO17 1BJ (United Kingdom)] [School of Physics and Astronomy, University of Southampton, Southampton SO17 1BJ (United Kingdom); Brassington, Nicola J.; Hardcastle, Martin J.; Goodger, Joanna L. [School of Physics, Astronomy, and Mathematics, University of Hertfordshire, Hatfield AL10 9AB (United Kingdom)] [School of Physics, Astronomy, and Mathematics, University of Hertfordshire, Hatfield AL10 9AB (United Kingdom); Kainulainen, Jouni [Max-Planck-Institute for Astronomy, Koenigstuhl 17, D-69117 Heidelberg (Germany)] [Max-Planck-Institute for Astronomy, Koenigstuhl 17, D-69117 Heidelberg (Germany); Woodley, Kristin A. [Department of Physics and Astronomy, University of British Columbia, Vancouver BC V6T 1Z1 (Canada)] [Department of Physics and Astronomy, University of British Columbia, Vancouver BC V6T 1Z1 (Canada); Sivakoff, Gregory R. [Department of Physics, University of Alberta, Edmonton, Alberta T6G 2E1 (Canada)] [Department of Physics, University of Alberta, Edmonton, Alberta T6G 2E1 (Canada); Gilfanov, Marat [Max-Planck-Institut fuer Astrophysik, Karl-Schwarzschild-Str. 1, D-85741, Garching (Germany)] [Max-Planck-Institut fuer Astrophysik, Karl-Schwarzschild-Str. 1, D-85741, Garching (Germany); Sarazin, Craig L. [Department of Astronomy, University of Virginia, P.O. Box 400325, Charlottesville, VA 22904-4325 (United States)] [Department of Astronomy, University of Virginia, P.O. Box 400325, Charlottesville, VA 22904-4325 (United States); Voss, Rasmus, E-mail: mburke@star.sr.bham.ac.uk [Department of Astrophysics/IMAPP, Radboud, University Nijmegen, P.O. Box 9010, NL-6500 GL Nijmegen (Netherlands)] [Department of Astrophysics/IMAPP, Radboud, University Nijmegen, P.O. Box 9010, NL-6500 GL Nijmegen (Netherlands); and others

2013-04-01T23:59:59.000Z

335

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

336

X-ray microscopy using grazing-incidence reflections optics  

SciTech Connect (OSTI)

The role of Kirkpatrick-Baez microscopes as the workhorse of the x-ray imaging devices is discussed. This role is being extended with the development of a 22X magnification Kirkpatrick-Baez x-ray microscope with multilayer x-ray mirrors. These mirrors can operate at large angles, high x-ray energies, and have a narrow, well defined x-ray energy bandpass. This will make them useful for numerous experiments. However, where a large solid angle is needed, the Woelter microscope will still be necessary and the technology needed to build them will be useful for many other types of x-ray optics.

Price, R.H.

1983-06-30T23:59:59.000Z

337

X-ray microscopy using grazing-incidence reflection optics  

SciTech Connect (OSTI)

The Kirkpatrick-Baez microscopes are described along with their role as the workhorse of the x-ray imaging devices. This role is being extended with the development of a 22X magnification Kirkpatrick-Baez x-ray microscope with multilayer x-ray mirrors. These mirrors can operate at large angles, high x-ray energies, and have a narrow, well defined x-ray energy bandpass. This will make them useful for numerous experiments. However, where a large solid angle is needed, the Woelter microscope will still be necessary and the technology needed to build them will be useful for many other types of x-ray optics.

Price, R.H.

1981-08-06T23:59:59.000Z

338

Rise Time Measurement for Ultrafast X-Ray Pulses  

DOE Patents [OSTI]

A pump-probe scheme measures the rise time of ultrafast x-ray pulses. Conventional high speed x-ray diagnostics (x-ray streak cameras, PIN diodes, diamond PCD devices) do not provide sufficient time resolution to resolve rise times of x-ray pulses on the order of 50 fs or less as they are being produced by modern fast x-ray sources. Here, we are describing a pump-probe technique that can be employed to measure events where detector resolution is insufficient to resolve the event. The scheme utilizes a diamond plate as an x-ray transducer and a p-polarized probe beam.

Celliers, Peter M.; Weber, Franz A.; Moon, Stephen J.

2005-04-05T23:59:59.000Z

339

Rise time measurement for ultrafast X-ray pulses  

DOE Patents [OSTI]

A pump-probe scheme measures the rise time of ultrafast x-ray pulses. Conventional high speed x-ray diagnostics (x-ray streak cameras, PIN diodes, diamond PCD devices) do not provide sufficient time resolution to resolve rise times of x-ray pulses on the order of 50 fs or less as they are being produced by modern fast x-ray sources. Here, we are describing a pump-probe technique that can be employed to measure events where detector resolution is insufficient to resolve the event. The scheme utilizes a diamond plate as an x-ray transducer and a p-polarized probe beam.

Celliers, Peter M. (Berkeley, CA); Weber, Franz A. (Oakland, CA); Moon, Stephen J. (Tracy, CA)

2005-04-05T23:59:59.000Z

340

X-ray imaging crystal spectrometer for extended X-ray sources  

DOE Patents [OSTI]

Spherically or toroidally curved, double focusing crystals are used in a spectrometer for X-ray diagnostics of an extended X-ray source such as a hot plasma produced in a tokomak fusion experiment to provide spatially and temporally resolved data on plasma parameters using the imaging properties for Bragg angles near 45. For a Bragg angle of 45.degree., the spherical crystal focuses a bundle of near parallel X-rays (the cross section of which is determined by the cross section of the crystal) from the plasma to a point on a detector, with parallel rays inclined to the main plain of diffraction focused to different points on the detector. Thus, it is possible to radially image the plasma X-ray emission in different wavelengths simultaneously with a single crystal.

Bitter, Manfred L. (Princeton, NJ); Fraenkel, Ben (Jerusalem, IL); Gorman, James L. (Bordentown, NJ); Hill, Kenneth W. (Lawrenceville, NJ); Roquemore, A. Lane (Cranbury, NJ); Stodiek, Wolfgang (Princeton, NJ); von Goeler, Schweickhard E. (Princeton, NJ)

2001-01-01T23:59:59.000Z

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


341

X-RAY POINT-SOURCE POPULATIONS CONSTITUTING THE GALACTIC RIDGE X-RAY EMISSION  

SciTech Connect (OSTI)

Apparently diffuse X-ray emission has been known to exist along the central quarter of the Galactic Plane since the beginning of X-ray astronomy; this is referred to as the Galactic Ridge X-ray emission (GRXE). Recent deep X-ray observations have shown that numerous X-ray point sources account for a large fraction of the GRXE in the hard band (2-8 keV). However, the nature of these sources is poorly understood. Using the deepest X-ray observations made in the Chandra bulge field, we present the result of a coherent photometric and spectroscopic analysis of individual X-ray point sources for the purpose of constraining their nature and deriving their fractional contributions to the hard-band continuum and Fe K line emission of the GRXE. Based on the X-ray color-color diagram, we divided the point sources into three groups: A (hard), B (soft and broad spectrum), and C (soft and peaked spectrum). The group A sources are further decomposed spectrally into thermal and non-thermal sources with different fractions in different flux ranges. From their X-ray properties, we speculate that the group A non-thermal sources are mostly active galactic nuclei and the thermal sources are mostly white dwarf (WD) binaries such as magnetic and non-magnetic cataclysmic variables (CVs), pre-CVs, and symbiotic stars, whereas the group B and C sources are X-ray active stars in flares and quiescence, respectively. In the log N-log S curve of the 2-8 keV band, the group A non-thermal sources are dominant above Almost-Equal-To 10{sup -14} erg cm{sup -2} s{sup -1}, which is gradually taken over by Galactic sources in the fainter flux ranges. The Fe K{alpha} emission is mostly from the group A thermal (WD binaries) and the group B (X-ray active stars) sources.

Morihana, Kumiko [Institute of Physical and Chemical Research (RIKEN), 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan)] [Institute of Physical and Chemical Research (RIKEN), 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Tsujimoto, Masahiro; Ebisawa, Ken [Japan Aerospace Exploration Agency, Institute of Space and Astronautical Science, 3-1-1 Yoshino-dai, Chuo-ku, Sagamihara, Kanagawa 252-5210 (Japan)] [Japan Aerospace Exploration Agency, Institute of Space and Astronautical Science, 3-1-1 Yoshino-dai, Chuo-ku, Sagamihara, Kanagawa 252-5210 (Japan); Yoshida, Tessei, E-mail: morihana@crab.riken.jp [National Astronomical Observatory of Japan, 2-21-1, Osawa, Mitaka, Tokyo 181-8588 (Japan)] [National Astronomical Observatory of Japan, 2-21-1, Osawa, Mitaka, Tokyo 181-8588 (Japan)

2013-03-20T23:59:59.000Z

342

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

343

A theoretical analysis of reflection of X-rays from water at energies relevant for diagnostics  

SciTech Connect (OSTI)

The reflection of X-rays from a semi-infinite water target, for energies used in X-ray diagnostics, is treated by the analog Monte Carlo simulation. In the developed procedure it was possible to calculate separately contributions of photons scattered, before reflection, fixed number of times with target electrons. It turned out that multiple collision type of reflection dominates at all energies investigated, whenever the absorption is small. The same process was also treated analytically as the classical albedo problem for isotropic scattering without energy loss. Very good agreement of results of the two approaches is obtained.

Arsenovic, Dusan [Institute of Physics, Pregrevica 118, P.O. Box 57, Belgrade (Serbia and Montenegro); Davidovic, Dragomir M.; Vukanic, Jovan [Vinca Institute of Nuclear Sciences, P.O Box 522, Belgrade (Serbia and Montenegro)

2003-01-24T23:59:59.000Z

344

ASCA Discovery of Diffuse 6.4 keV Emission Near the Sgr C Complex: A New X-ray Reflection Nebula  

E-Print Network [OSTI]

We present an ASCA discovery of diffuse hard X-ray emission from the Sgr C complex with its peak in the vicinity of the molecular cloud core. The X-ray spectrum is characterized by a strong 6.4-keV line and large absorption. These properties suggest that Sgr C is a new X-ray reflection nebula which emits fluorescent and scattered X-rays via irradiation from an external X-ray source. We found no adequately bright source in the immediate Sgr C vicinity to fully account for the fluorescence. The irradiating source may be the Galactic nucleus Sgr A*, which was brighter in the past than it is now as is suggested from observations of the first X-ray reflection nebula Sgr B2.

H. Murakami; K. Koyama; M. Tsujimoto; Y. Maeda; M. Sakano

2000-12-14T23:59:59.000Z

345

High resolution x-ray microscope  

SciTech Connect (OSTI)

The authors present x-ray images of grid meshes and biological material obtained using a microspot x-ray tube with a multilayer optic and a 92-element parabolic compound refractive lens (CRL) made of a plastic containing only hydrogen and carbon. Images obtained using this apparatus are compared with those using an area source with a spherical lens and a spherical lens with multilayer condenser. The authors found the best image quality using the multilayer condenser with a parabolic lens, compared to images with a spherical lens and without the multilayer optics. The resolution was measured using a 155-element parabolic CRL and a multilayer condenser with the microspot tube. The experiment demonstrates about 1.1 {mu}m resolution.

Gary, C. K.; Park, H.; Lombardo, L. W.; Piestrup, M. A.; Cremer, J. T.; Pantell, R. H.; Dudchik, Y. I. [Adelphi Technology, Inc. 981-B Industrial Road, San Carlos, California 94070 (United States); Department of Electrical Engineering, Stanford University, Stanford, California 94305 (United States); Institute of Applied Physics Problems, Kurchatova 7, Minsk 220064 (Belarus)

2007-04-30T23:59:59.000Z

346

X-ray radiography for container inspection  

DOE Patents [OSTI]

Arrangements of X-ray inspection systems are described for inspecting high-z materials in voluminous objects such as containers. Inspection methods may involve generating a radiographic image based on detected attenuation corresponding to a pulsed beams of radiation transmitted through a voluminous object. The pulsed beams of radiation are generated by a high-energy source and transmitted substantially downward along an incident angle, of approximately 1.degree. to 30.degree., to a vertical axis extending through the voluminous object. The generated radiographic image may be analyzed to detect on localized high attenuation representative of high-z materials and to discriminate high-z materials from lower and intermediate-z materials on the basis of the high density and greater attenuation of high-z material for higher energy (3-10 MeV) X-rays, and the compact nature of threatening masses of fissionable materials.

Katz, Jonathan I. (Clayton, MO); Morris, Christopher L. (Los Alamos, NM)

2011-06-07T23:59:59.000Z

347

X-ray emission from the planet pulsar B1257+12  

E-Print Network [OSTI]

We report the detection of the millisecond pulsar B1257+12 with the Chandra X-ray Observatory. In a 20 ks exposure we detected 25 photons from the pulsar, with energies between 0.4 and 2.0 keV, corresponding to the flux F_X=(4.4+/- 0.9)*10^{-15} ergs s^{-1} cm^{-2} in this energy range. The X-ray spectrum can be described by a power-law model with photon index Gamma = 2.8 and luminosity L_X \\approx 2.5*10^{29} ergs s^{-1} in the 0.3--8 keV band, for a plausible distance of 500 pc and hydrogen column density N_H=3*10^{20} cm^{-2}. Alternatively, the spectrum can be fitted by a blackbody model with kT ~ 0.22 keV and projected emitting area ~2000 m^2. If the thermal X-rays are emitted from two symmetric polar caps, the bolometric luminosity of the two caps is 2 L_bol ~ 3*10^{29} ergs s^{-1}. We compared our results with the data on other 30 millisecond pulsars observed in X-rays and found that the apparent X-ray efficiency of PSR B1257+12, L_X/Edot ~ 3*10^{-5} for d=500 pc, is lower than those of most of millisecond pulsars. This might be explained by an unfavorable orientation of the X-ray pulsar beam if the radiation is magnetospheric, or by strong asymmetry of polar caps if the radiation is thermal (e.g., one of the polar caps is much brighter than the other and remains invisible for most part of the pulsar period). Alternatively, it could be attributed to absorption of X-rays in circumpulsar matter, such as a flaring debris disk left over after formation of the planetary system around the pulsar.

G. G. Pavlov; O. Kargaltsev; G. P. Garmire; A. Wolszczan

2007-04-17T23:59:59.000Z

348

Biological Imaging by Soft X-Ray Diffraction Microscopy  

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

Biological Imaging by Soft X-Ray Diffraction Microscopy Print Electron and x-ray microscopes are a valuable tool for both the life and materials sciences, but they are limited in...

349

The X-ray Microcalorimeter Spectrometer onboard of IXO  

E-Print Network [OSTI]

One of the instruments on the International X-ray Observatory (IXO), under study with NASA, ESA and JAXA, is the X-ray Microcalorimeter Spectrometer (XMS). This instrument, which will provide high spectral resolution images, ...

Figueroa-Feliciano, Enectali

350

Resonant Soft X-Ray Scattering - Combining Structural with Spectroscop...  

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

Resonant Soft X-Ray Scattering - Combining Structural with Spectroscopic Refinement Friday, September 28, 2012 - 10:00am SLAC, Bldg. 137, Room 322 SSRL Presents Kevin Stone X-ray...

351

On the origin of X-ray dips in Her X-1  

E-Print Network [OSTI]

A strong X-ray illumination of the optical star atmosphere in Her X-1, asymmetric because of a partial shadowing by the tilted twisted accretion disk around central neutron star, leads to the formation of matter flows coming out of the orbital plane and crossing the line of sight before entering the disk. We suggest that the absorption of X-ray emission by this flow leads to the formation of pre-eclipse and anomalous dips of type I. These dips are observed during several orbits after turn-on both in the main-on and short-on state. Almost coherent action of tidal torques and matter streams enhances the disk wobbling which causes the disk edge to shield the X-ray source after the turn-on. Anomalous dips of type II and post-eclipse recovery appear due to this process only on the first orbit after turn-on.

N. I. Shakura; M. E. Prokhorov; K. A. Postnov; N. A. Ketsaris

1999-02-09T23:59:59.000Z

352

Sample holder for X-ray diffractometry  

DOE Patents [OSTI]

A sample holder for use with X-ray diffractometers with the capability to rotate the sample, as well as to adjust the position of the sample in the x, y, and z directions. Adjustment in the x direction is accomplished through loosening set screws, moving a platform, and retightening the set screws. Motion translators are used for adjustment in the y and z directions. An electric motor rotates the sample, and receives power from the diffractometer.

Hesch, Victor L. (Los Alamos, NM)

1992-01-01T23:59:59.000Z

353

Columbia University X-Ray Measurements  

E-Print Network [OSTI]

V-720 keV · NaI 2x2x2" detector views an energy range of 1 keV-3 MeV Store signal in the tree. computer configuration. Plasmas were created using multi-frequency ECRH, and we find that most of the plasma energy is stored in the fast electrons. The energy spectrum of the x-ray emission below 740 keV is measured

354

X-rays from Supernova Remnants  

E-Print Network [OSTI]

A summary of X-ray observations of supernova remnants is presented including the explosion fragment A of the Vela SNR, Tycho, N132D, RX J0852-4622, the Crab Nebula and the 'bulls eye', and SN 1987A, high-lighting the progress made with Chandra and XMM-Newton and touching upon the questions which arise from these observations and which might inspire future research.

B. Aschenbach

2002-08-28T23:59:59.000Z

355

Trends in the Carbonyl Core (C 1S, O 1S) f *C)O Transition in the Near-Edge X-ray Absorption Fine Structure Spectra of Organic Molecules  

E-Print Network [OSTI]

,2 meteorites3 and interplanetary dust particles,4 eocene and recent wood,5,6 coal, coke, and other organic

356

X-ray Free-electron Lasers  

SciTech Connect (OSTI)

In a free-electron laser (FEL) the lasing medium is a high-energy beam of electrons flying with relativistic speed through a periodic magnetic field. The interaction between the synchrotron radiation that is produced and the electrons in the beam induces a periodic bunching of the electrons, greatly increasing the intensity of radiation produced at a particular wavelength. Depending only on a phase match between the electron energy and the magnetic period, the wavelength of the FEL radiation can be continuously tuned within a wide spectral range. The FEL concept can be adapted to produce radiation wavelengths from millimeters to Angstroms, and can in principle produce hard x-ray beams with unprecedented peak brightness, exceeding that of the brightest synchrotron source by ten orders of magnitude or more. This paper focuses on short-wavelength FELs. It reviews the physics and characteristic properties of single-pass FELs, as well as current technical developments aiming for fully coherent x-ray radiation pulses with pulse durations in the 100 fs to 100 as range. First experimental results at wavelengths around 100 nm and examples of scientific applications planned on the new, emerging x-ray FEL facilities are presented.

Feldhaus, J.; /DESY; Arthur, J.; Hastings, J.B.; /SLAC

2007-02-23T23:59:59.000Z

357

The X-ray Telescope of CAST  

E-Print Network [OSTI]

The Cern Axion Solar Telescope (CAST) is in operation and taking data since 2003. The main objective of the CAST experiment is to search for a hypothetical pseudoscalar boson, the axion, which might be produced in the core of the sun. The basic physics process CAST is based on is the time inverted Primakoff effect, by which an axion can be converted into a detectable photon in an external electromagnetic field. The resulting X-ray photons are expected to be thermally distributed between 1 and 7 keV. The most sensitive detector system of CAST is a pn-CCD detector combined with a Wolter I type X-ray mirror system. With the X-ray telescope of CAST a background reduction of more than 2 orders off magnitude is achieved, such that for the first time the axion photon coupling constant g_agg can be probed beyond the best astrophysical constraints g_agg < 1 x 10^-10 GeV^-1.

M. Kuster; H. Bruninger; S. Cbrian; M. Davenport; C. Elefteriadis; J. Englhauser; H. Fischer; J. Franz; P. Friedrich; R. Hartmann; F. H. Heinsius; D. H. H. Hoffmann; G. Hoffmeister; J. N. Joux; D. Kang; K. Knigsmann; R. Kotthaus; T. Papaevangelou; C. Lasseur; A. Lippitsch; G. Lutz; J. Morales; A. Rodrguez; L. Strder; J. Vogel; K. Zioutas

2007-05-10T23:59:59.000Z

358

X-Ray Searches for Solar Axions  

E-Print Network [OSTI]

Axions generated thermally in the solar core can convert nearly directly to X-rays as they pass through the solar atmosphere via interaction with the magnetic field. The result of this conversion process would be a diffuse centrally-concentrated source of few-keV X-rays at disk center; it would have a known dimension, of order 10% of the solar diameter, and a spectral distribution resembling the blackbody spectrum of the solar core. Its spatial structure in detail would depend on the distribution of mass and field in the solar atmosphere. The brightness of the source depends upon these factors as well as the unknown coupling constant and the unknown mass of the axion; this particle is hypothetical and no firm evidence for its existence has been found yet. We describe the solar magnetic environment as an axion/photon converter and discuss the upper limits obtained by existing and dedicated observations from three solar X-ray observatories: Yohkoh, RHESSI, and Hinode

Hugh S. Hudson; L. W. Acton; E. DeLuca; I. G. Hannah; K. Reardon; K. Van Bibber

2012-01-22T23:59:59.000Z

359

Applications of holography to x-ray imaging  

SciTech Connect (OSTI)

In this paper we consider various applications of holographic techniques to the problem of soft x-ray imaging. We give special attention to imaging biological material using x-rays in the wavelength range 24 to 45A. We describe some experiments on formation and reconstruction of x-ray holograms and propose some ways in which holographic techniques might contribute to the difficult problem of fabricating optical elements for use in the soft x-ray region.

Howells, M.; Iarocci, M.; Kenney, J.; Rarback, H.; Rosser, R.; Yun, W.

1985-03-01T23:59:59.000Z

360

Applications of holography to X-ray imaging  

SciTech Connect (OSTI)

In this paper the authors consider various applications of holographic techniques to the problem of soft x-ray imaging. Special attention is given to imaging biological material using x-rays in the wavelength range 24-45A. The authors describe some experiments on formation and reconstruction of x-ray holograms and propose some ways in which holographic techniques might contribute to the difficult problem of fabricating optical elements for use in the soft x-ray region.

Howells, M.; Iarocci, M.; Kenney, J.; Rarback, H.; Rosser, R.; Yun, W.

1985-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "x-ray absorption fine" 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 MicroCT Training Presentation  

E-Print Network [OSTI]

X-ray MicroCT Training Presentation T. Fettah Kosar, PhD Center for Nanoscale Systems Harvard) Model: HMXST225 (max. 225 kV) #12;Overview 3 Introduction to X-ray imaging and Computed Tomography (CT) · What are X-rays and how do we generate and image them? · How do we magnify X-ray images and keep them

362

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

363

Theoretical X-ray Line Profiles from Colliding Wind Binaries  

E-Print Network [OSTI]

We present theoretical X-ray line profiles from a range of model colliding wind systems. In particular, we investigate the effects of varying the stellar mass-loss rates, the wind speeds, and the viewing orientation. We find that a wide range of theoretical line profile shapes is possible, varying with orbital inclination and phase. At or near conjunction, the lines have approximately Gaussian profiles, with small widths (HWHM ~ 0.1 v_infty) and definite blue- or redshifts (depending on whether the star with the weaker wind is in front or behind). When the system is viewed at quadrature, the lines are generally much broader (HWHM ~ v_infty), flat-topped and unshifted. Local absorption can have a major effect on the observed profiles - in systems with mass-loss rates of a few times 10^{-6} Msol/yr the lower energy lines (E wind of the primary. The orbital variation ...

Henley, D B; Pittard, J M

2003-01-01T23:59:59.000Z

364

Femtosecond laser-electron x-ray source  

DOE Patents [OSTI]

A femtosecond laser-electron X-ray source. A high-brightness relativistic electron injector produces an electron beam pulse train. A system accelerates the electron beam pulse train. The femtosecond laser-electron X-ray source includes a high intra-cavity power, mode-locked laser and an x-ray optics system.

Hartemann, Frederic V.; Baldis, Hector A.; Barty, Chris P.; Gibson, David J.; Rupp, Bernhard

2004-04-20T23:59:59.000Z

365

X-ray Diffraction Laboratory Department of Chemistry  

E-Print Network [OSTI]

X-ray Diffraction Laboratory Department of Chemistry Texas A & M University College Station, Texas Phone : 979-845-9125 www.chem.tamu.edu/xray xray@tamu.edu X-rayDiffractionLaboratory DepartmentofChemistry 3255TAMU CollegeStation,TX77843-3255 Mission The purpose of our laboratory is to provide X-ray

Meagher, Mary

366

X-ray Diffraction Practicals 1 Graphics Programs  

E-Print Network [OSTI]

X-ray Diffraction Practicals 1 Graphics Programs that will read SHELX or CIF files J. Reibenspies, N. Bhuvanesh ver 1.0.0 #12;X-ray Diffraction Practicals 2 Free software. Gretep : Reads SHELX files shelx files or output thermal ellipsoid plots. http://www.umass.edu/microbio/rasmol/ #12;X-ray

Meagher, Mary

367

X-ray Emission from Massive Stars David Cohen  

E-Print Network [OSTI]

X-ray Emission from Massive Stars David Cohen Department of Physics and Astronomy Swarthmore University, Oct. 13, 2005 astro.swarthmore.edu/~cohen/ #12;Outline 1. What you need to know: a. X-rays from the Sun - magnetic activity, x-ray spectra b. Hot stars c. Radiation-driven winds and the Doppler shift d

Cohen, David

368

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

369

Quantitative x-ray imager (abstract)  

SciTech Connect (OSTI)

We report on development of a quantitative x-ray imager (QXI) for the national Inertial Confinement Fusion Program. Included in this development is a study of photocathode response as a function of photon energy, 2--17.5 keV, which is related to diagnostic development on the National Ignition Facility (NIF). The QXI is defined as being a quantative imager due to the repeated characterization. This instrument is systematically checked out, electronically as well as its photocathode x-ray response, both on a direct current and pulsed x-ray sources, before and after its use on a shot campaign. The QXI is a gated x-ray imager1 used for a variety of experiments conducted in the Inertial Confinement Fusion and Radiation Physics Program. The camera was assembled in Los Alamos and has been under development since 1997 and has now become the workhorse framing camera by the program. The electronics were built by Grant Applied Physics of San Fransisco, CA.2 The QXI has been used at the LANL Trident, LLNL Nova, and University of Rochester Laboratory OMEGA laser facilities. The camera consists of a grated microchannel plate (MCP), a phosphor coated fiberoptic faceplate coupled to film for data readout, along with high speed electronic pulsers to drive the x-ray detector. The QXI has both a two-strip and a four-strip detection head and has the ability to individually bias the gain of each of the strips. The timing of the QXI was done at the Trident short pulse laboratory, using 211 nm light. Single strip jitter was looked at as well and determined to be <25 ps. Flatfielding of the photocathode across the MCP was done with the Trident main laser with 150 J on a gold disk with a 1 ns. Spatial resolution was determined to be <5 {mu}m by using the same laser conditions as before and a backlit 1000 lp/in. grid. The QXI has been used on cylindrical implosion work at the Nova Laser Facility, and on direct-drive cylinder mix and indirect-drive high convergence implosion experiments at OMEGA. Its two-strip module has provided the capability to look at point backlighters, as part of technique development for experiments on the NIF. Its next use will be in March 2000 with its off axis viewer nose at Omega, providing a perpendicular view of Rayleigh--Taylor spike dissipation.

Evans, Scott C.; Archuleta, Tom N.; Oertel, John A.; Walsh, Peter J.

2001-01-01T23:59:59.000Z

370

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

371

THREE-DIMENSIONAL IMAGING OF NANOSCALE MATERIALS BY UISNG COHERENT X-RAYS  

SciTech Connect (OSTI)

X-ray crystallography is currently the primary methodology used to determine the 3D structure of materials and macromolecules. However, many nanostructures, disordered materials, biomaterials, hybrid materials and biological specimens are noncrystalline and, hence, their structures are not accessible by X-ray crystallography. Probing these structures therefore requires the employment of different approaches. A very promising technique currently under rapid development is X-ray diffraction microscopy (or lensless imaging), in which the coherent X-ray diffraction pattern of a noncrystalline specimen is measured and then directly phased to obtain a high-resolution image. Through the DOE support over the past three years, we have applied X-ray diffraction microscopy to quantitative imaging of GaN quantum dot particles, and revealed the internal GaN-Ga2O3 core shell structure in three dimensions. By exploiting the abrupt change in the scattering cross-section near electronic resonances, we carried out the first experimental demonstration of resonant X-ray diffraction microscopy for element specific imaging. We performed nondestructive and quantitative imaging of buried Bi structures inside a Si crystal by directly phasing coherent X-ray diffraction patterns acquired below and above the Bi M5 edge. We have also applied X-ray diffraction microscopy to nondestructive imaging of mineral crystals inside biological composite materials - intramuscular fish bone - at the nanometer scale resolution. We identified mineral crystals in collagen fibrils at different stages of mineralization and proposed a dynamic mechanism to account for the nucleation and growth of mineral crystals in the collagen matrix. In addition, we have also discovered a novel 3D imaging modality, denoted ankylography, which allows for complete 3D structure determination without the necessity of sample titling or scanning. We showed that when the diffraction pattern of a finite object is sampled at a sufficiently fine scale on the Ewald sphere, the 3D structure of the object is determined by the 2D spherical pattern. We confirmed the theoretical analysis by performing 3D numerical reconstructions of a sodium silicate glass structure at 2 ? resolution from a 2D spherical diffraction pattern alone. As X-ray free electron lasers are under rapid development worldwide, ankylography may open up a new horizon to obtain the 3D structure of a non-crystalline specimen from a single pulse and allow time-resolved 3D structure determination of disordered materials.

Jianwei Miao

2011-04-18T23:59:59.000Z

372

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

373

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

374

Calibrating X-ray Imaging Devices for Accurate Intensity Measurement  

SciTech Connect (OSTI)

The purpose of the project presented is to develop methods to accurately calibrate X-ray imaging devices. The approach was to develop X-ray source systems suitable for this endeavor and to develop methods to calibrate solid state detectors to measure source intensity. NSTec X-ray sources used for the absolute calibration of cameras are described, as well as the method of calibrating the source by calibrating the detectors. The work resulted in calibration measurements for several types of X-ray cameras. X-ray camera calibration measured efficiency and efficiency variation over the CCD. Camera types calibrated include: CCD, CID, back thinned (back illuminated), front illuminated.

Haugh, M. J.

2011-07-28T23:59:59.000Z

375

Proceedings of the workshop on X-ray computed microtomography  

SciTech Connect (OSTI)

This report consists of vugraphs from the nine presentations at the conference. Titles of the presentations are: CMT: Applications and Techniques; Computer Microtomography Using X-rays from Third Generation Synchrotron X-ray; Approaches to Soft-X-ray Nanotomography; Diffraction Enhanced Tomography; X-ray Computed Microtomography Applications at the NSLS; XCMT Applications in Forestry and Forest Products; 3DMA: Investigating Three Dimensional Pore Geometry from High Resolution Images; X-ray Computed Microtomography Studies of Volcanic Rock; and 3-D Visualization of Tomographic Volumes.

NONE

1998-02-01T23:59:59.000Z

376

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, Universit du Qubec, 1650 Lionel Boulet, Varennes, Qubec J3X 1S2 (Canada)] [INRS-EMT, Universit du Qubec, 1650 Lionel Boulet, Varennes, Qubec 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

377

X-Ray Source Based on the Parametric X-Rays  

E-Print Network [OSTI]

Prospects of parametric x-rays (PXR) application for the development of a tuneable quasi-monochromatic x-ray source for medical imaging are discussed. Analysis of basic requirements for electron accelerator shows that it must be relatively low-energy and high-current linac. In comparison with known ultra-relativistic cases, at low energies PXR properties will be modified to a great extent by multiple scattering of the electrons. PXR intensity dependence on target thickness and beam energy are calculated taking multiple scattering into account. It is concluded that PXR source based on real medical accelerators is feasible and can provide x-ray flux needful for obtaining high quality medical images.

Alexander Lobko; Olga Lugovskaya

2005-09-02T23:59:59.000Z

378

EVIDENCE OF CONTRIBUTION OF INTERVENING CLOUDS TO GAMMA-RAY BURST'S X-RAY COLUMN DENSITY  

SciTech Connect (OSTI)

The origin of excess of X-ray column density with respect to optical extinction in gamma-ray bursts (GRBs) is still a puzzle. A proposed explanation of the excess is the photoelectric absorption due to the intervening clouds along a GRB's line of sight. Here, we test this scenario by using the intervening Mg II absorption as a tracer of the neutral hydrogen column density of the intervening clouds. We identify a connection between the large X-ray column density (and large column density ratio of log (N{sub H,X}/N{sub H{sub I}})?0.5) and large neutral hydrogen column density probed by the Mg II doublet ratio (DR). In addition, GRBs with large X-ray column density (and large ratio of log (N{sub H,X}/N{sub H{sub I}})>0) tend to have multiple saturated intervening absorbers with DR < 1.2. These results therefore indicate an additional contribution from the intervening system to the observed X-ray column density in some GRBs, although the contribution from the host galaxy alone cannot be excluded based on this study.

Wang, J., E-mail: wj@bao.ac.cn [National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012 (China)

2013-10-20T23:59:59.000Z

379

Apparatus for monitoring X-ray beam alignment  

DOE Patents [OSTI]

A self-contained, hand-held apparatus is provided for monitoring alignment of an X-ray beam in an instrument employing an X-ray source. The apparatus includes a transducer assembly containing a photoresistor for providing a range of electrical signals responsive to a range of X-ray beam intensities from the X-ray beam being aligned. A circuit, powered by a 7.5 VDC power supply and containing an audio frequency pulse generator whose frequency varies with the resistance of the photoresistor, is provided for generating a range of audible sounds. A portion of the audible range corresponds to low X-ray beam intensity. Another portion of the audible range corresponds to high X-ray beam intensity. The transducer assembly may include an a photoresistor, a thin layer of X-ray fluorescent material, and a filter layer transparent to X-rays but opaque to visible light. X-rays from the beam undergoing alignment penetrate the filter layer and excite the layer of fluorescent material. The light emitted from the fluorescent material alters the resistance of the photoresistor which is in the electrical circuit including the audio pulse generator and a speaker. In employing the apparatus, the X-ray beam is aligned to a complete alignment by adjusting the X-ray beam to produce an audible sound of the maximum frequency. 2 figures.

Steinmeyer, P.A.

1991-10-08T23:59:59.000Z

380

Apparatus for monitoring X-ray beam alignment  

DOE Patents [OSTI]

A self-contained, hand-held apparatus is provided for minitoring alignment of an X-ray beam in an instrument employing an X-ray source. The apparatus includes a transducer assembly containing a photoresistor for providing a range of electrical signals responsive to a range of X-ray beam intensities from the X-ray beam being aligned. A circuit, powered by a 7.5 VDC power supply and containing an audio frequency pulse generator whose frequency varies with the resistance of the photoresistor, is provided for generating a range of audible sounds. A portion of the audible range corresponds to low X-ray beam intensity. Another portion of the audible range corresponds to high X-ray beam intensity. The transducer assembly may include an a photoresistor, a thin layer of X-ray fluorescent material, and a filter layer transparent to X-rays but opaque to visible light. X-rays from the beam undergoing alignment penetrate the filter layer and excite the layer of fluorescent material. The light emitted from the fluorescent material alters the resistance of the photoresistor which is in the electrical circuit including the audio pulse generator and a speaker. In employing the apparatus, the X-ray beam is aligned to a complete alignment by adjusting the X-ray beam to produce an audible sound of the maximum frequency.

Steinmeyer, Peter A. (Arvada, CO)

1991-10-08T23:59:59.000Z

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381

Comparison of SOFC Cathode Microstructure Quantified using X-ray Nanotomography and Focused Ion Beam - Scanning Electron Microscopy  

SciTech Connect (OSTI)

X-ray nanotomography and focused ion beam scanning electron microscopy (FIB?SEM) have been applied to investigate the complex 3D microstructure of solid oxide fuel cell (SOFC) electrodes at spatial resolutions of 45 nm and below. The application of near edge differential absorption for x-ray nanotomography and energy selected backscatter detection for FIBSEM enable elemental mapping within the microstructure. Using these methods, non?destructive 3D x-ray imaging and FIBSEM serial sectioning have been applied to compare three?dimensional elemental mapping of the LSM, YSZ, and pore phases in the SOFC cathode microstructure. The microstructural characterization of an SOFC cathode is reported based on these measurements. The results presented demonstrate the viability of x-ray nanotomography as a quantitative characterization technique and provide key insights into the SOFC cathode microstructure.

Nelson, George J.; Harris, William H.; Lombardo, Jeffrey J.; Izzo, Jr., John R.; Chiu, W. K. S.; Tanasini, Pietro; cantoni, Marco; Van herle, Jan; Comninellis, Christos; Andrews, Joy C.; Liu, Yijin; Pianetta, Piero; Chu, Yong

2011-01-01T23:59:59.000Z

382

Neutron and X-Ray Studies of Advanced Materials V: CENTENNIAL  

SciTech Connect (OSTI)

In 2012 the diffraction community will celebrate 100 years since the prediction of X-ray diffraction by M. Laue, and following his suggestion the first beautiful diffraction experiment by W. Friedrich and P. Knipping. The significance of techniques based on the analysis of the diffraction of X-rays, neutrons, electrons and Mossbauer photons discovered later, has continued to increase in the past 100 years. The aim of this symposium is to provide a forum for discussion of using state-of-the-art neutron and X-ray scattering techniques for probing advanced materials. These techniques have been widely used to characterize materials structures across all length scales, from atomic to nano, meso, and macroscopic scales. With the development of sample environments, in-situ experiments, e.g., at temperatures and applied mechanical load, are becoming routine. The development of ultra-brilliant third-generation synchrotron X-ray sources, together with advances in X-ray optics, has created intense X-ray microbeams, which provide the best opportunities for in-depth understanding of mechanical behavior in a broad spectrum of materials. Important applications include ultra-sensitive elemental detection by X-ray fluorescence/absorption and microdiffraction to identify phase and strain with submicrometer spatial resolution. X-ray microdiffraction is a particularly exciting application compared with alternative probes of crystalline structure, orientation and strain. X-ray microdiffraction is non-destructive with good strain resolution, competitive or superior spatial resolution in thick samples, and with the ability to probe below the sample surface. Advances in neutron sources and instrumentation also bring new opportunities in neutron scattering research. In addition to characterizing the structures, neutrons are also a great tool for elucidating the dynamics of materials. Because neutrons are highly penetrating, neutrons have been used to map stress in engineering systems. Neutrons have also played a vital role in our understanding of the magnetism and magnetic properties. Specialized instruments have been built to gain physical insights of the fundamental mechanisms governing phase transformation and mechanical behaviors of materials. The application of those techniques, in combination with theoretical simulations and numerical modeling, will lead to major breakthroughs in materials science in the foreseeable future that will contribute to the development of materials technology and industrial innovation.

Spanos, George

2012-05-01T23:59:59.000Z

383

High-Resolution Soft X-Ray Spectral Analysis in the CK Region of Titanium Carbide (TiC) using the DV-X alpha Molecular Orbital Method  

SciTech Connect (OSTI)

We used the DV-X alpha method to analyze the high-resolution soft X-ray emission and absorption spectra in the CK region of titanium carbide (TiC). The spectral profiles of the X-ray emission and absorption can be ssuscfucelly reproduced by the occupied and unoccupied density of states (DOS ), respectively, in the C2p orbitals of the center carbon atoms in a Ti62C63 cluster model, suggesting that the center carbon atom in a large cluster model expanded to the cubic-structured 53 (= 125) atoms provides sufficient DOS for the X-ray spectral analysis of rock-salt structured metal carbides.

Shimomura, Kenta; Muramatsu, Yasuji; Denlinger, Jonathan D.; Gullikson, Eric M.

2008-10-31T23:59:59.000Z

384

X-ray emission properties of galaxies in Abell 3128  

E-Print Network [OSTI]

We use archival Chandra X-ray Observatory data to investigate X-ray emission from early-type galaxies in the rich z=0.06 cluster Abell 3128. By combining the X-ray count-rates from an input list of optically-selected galaxies, we obtain a statistical detection of X-ray flux, unbiased by X-ray selection limits. Using 87 galaxies with reliable Chandra data, X-ray emission is detected for galaxies down to M_B ~ -19.0, with only an upper limit determined for galaxies at M_B ~ -18.3. The ratio of X-ray to optical luminosities is consistent with recent determinations of the low-mass X-ray binary content of nearby elliptical galaxies. Taken individually, in contrast, we detect significant (3sigma) flux for only six galaxies. Of these, one is a foreground galaxy, while two are optically-faint galaxies with X-ray hardness ratios characteristic of active galactic nuclei. The remaining three detected galaxies are amongst the optically-brightest cluster members, and have softer X-ray spectra. Their X-ray flux is higher than that expected from X-ray binaries, by a factor 2-10; the excess suggests these galaxies have retained their hot gaseous haloes. The source with the highest L_X / L_B ratio is of unusual optical morphology with prominent sharp-edged shells. Notwithstanding these few exceptions, the cluster population overall exhibits X-ray properties consistent with their emission being dominated by X-ray binaries. We conclude that in rich cluster environments, interaction with the ambient intra-cluster medium acts to strip most galaxies of their hot halo gas.

Russell J. Smith

2003-07-15T23:59:59.000Z

385

X-ray generation using carbon nanotubes  

E-Print Network [OSTI]

of these sys- tems are illustrated in Figure 2(b) also outlines the principle mode of operation. Here, sealed in an inexpensive and eas- ily fabricated evacuated glass or ceramic envelope, the elec- trons are liberated from a metallic filament, often made... - ment of CNT-based FE sources is provided in [152]. Here we provide a condensed review of the progress, as it pertains to X-ray sources, since then. CNTs have some of the highest attainable aspect ratios, high thermal conductivity, low chemical...

Parmee, Richard J.; Collins, Clare M.; Milne, William I.; Cole, Matthew T.

2015-01-06T23:59:59.000Z

386

Lensless X-Ray Imaging in Reflection  

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 MayAtmospheric Optical Depth7-1D: VegetationEquipment Surfaces and Interfaces Sample6, 2011 LawrenceE C H NLensless X-Ray Imaging in

387

Lensless X-Ray Imaging in Reflection  

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 MayAtmospheric Optical Depth7-1D: VegetationEquipment Surfaces and Interfaces Sample6, 2011 LawrenceE C H NLensless X-Ray Imaging

388

Lensless X-Ray Imaging in Reflection  

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 MayAtmospheric Optical Depth7-1D: VegetationEquipment Surfaces and Interfaces Sample6, 2011 LawrenceE C H NLensless X-Ray ImagingLensless

389

Lensless X-Ray Imaging in Reflection  

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 MayAtmospheric Optical Depth7-1D: VegetationEquipment Surfaces and Interfaces Sample6, 2011 LawrenceE C H NLensless X-Ray

390

SMB, Small Angle X-Ray Scattering  

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 Scattering

391

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

392

X-ray Microscopy and Imaging: FAQs  

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 ComputedOverFrequently

393

X-rays Illuminate Ancient Archimedes Text  

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

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394

X-Ray Nanoimaging: Instruments and Methods  

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

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395

X-Ray Science Division (XSD)  

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

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396

Gamma Radiation & X-Rays  

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 MayAtmospheric Optical Depth7-1D: Vegetation ProposedUsingFun with Big Sky Learning Fun with Big SkyDIII-DRMRGamma Radiation and X-Rays 1.

397

Femtosecond X-ray protein nanocrystallography  

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

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398

Lensless X-Ray Imaging in Reflection  

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

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399

Lensless X-Ray Imaging in Reflection  

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

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400

Lensless X-Ray Imaging in Reflection  

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

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Note: This page contains sample records for the topic "x-ray absorption fine" 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

The BMW X-ray Cluster Survey  

E-Print Network [OSTI]

We describe the main features of the BMW survey of serendipitous X-ray clusters, based on the still unexploited ROSAT-HRI archival observations. The sky coverage, surface density and first deep optical CCD images of the candidates indicate that this sample can represent an excellent complement to the existing PSPC deep cluster surveys and will provide us with a fully independent probe of the evolution of the cluster abundance, in addition to significantly increasing the number of clusters known at z>0.6.

Alberto Moretti; Luigi Guzzo; Sergio Campana; Stefano Covino; Davide Lazzati; Marcella Longhetti; Emilio Molinari; Maria Rosa Panzera; Gianpiero Tagliaferri; Ian Dell'Antonio

2001-03-21T23:59:59.000Z

402

The BMW X-ray Cluster Survey  

E-Print Network [OSTI]

We describe the main features of the BMW survey of serendipitous X-ray clusters, based on the still unexploited ROSAT-HRI archival observations. The sky coverage, surface density and first deep optical CCD images of the candidates indicate that this sample can represent an excellent complement to the existing PSPC deep cluster surveys and will provide us with a fully independent probe of the evolution of the cluster abundance, in addition to significantly increasing the number of clusters known at z>0.6.

Moretti, A; Campana, S; Covino, S; Lazzati, D; Longhetti, M; Molinari, E; Panzera, M R; Tagliaferri, G; Dell'Antonio, I P; Moretti, Alberto; Guzzo, Luigi; Campana, Sergio; Covino, Stefano; Lazzati, Davide; Longhetti, Marcella; Molinari, Emilio; Panzera, Maria Rosa; Tagliaferri, Gianpiero; Antonio, Ian Dell'

2001-01-01T23:59:59.000Z

403

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

404

Single x-ray transmission system for bone mineral density determination  

SciTech Connect (OSTI)

Bones are the support of the body. They are composed of many inorganic compounds and other organic materials that all together can be used to determine the mineral density of the bones. The bone mineral density is a measure index that is widely used as an indicator of the health of the bone. A typical manner to evaluate the quality of the bone is a densitometry study; a dual x-ray absorptiometry system based study that has been widely used to assess the mineral density of some animals' bones. However, despite the success stories of utilizing these systems in many different applications, it is a very expensive method that requires frequent calibration processes to work properly. Moreover, its usage in small species applications (e.g., rodents) has not been quite demonstrated yet. Following this argument, it is suggested that there is a need for an instrument that would perform such a task in a more reliable and economical manner. Therefore, in this paper we explore the possibility to develop a new, affordable, and reliable single x-ray absorptiometry system. The method consists of utilizing a single x-ray source, an x-ray image sensor, and a computer platform that all together, as a whole, will allow us to calculate the mineral density of the bone. Utilizing an x-ray transmission theory modified through a version of the Lambert-Beer law equation, a law that expresses the relationship among the energy absorbed, the thickness, and the absorption coefficient of the sample at the x-rays wavelength to calculate the mineral density of the bone can be advantageous. Having determined the parameter equation that defines the ratio of the pixels in radiographies and the bone mineral density [measured in mass per unit of area (g/cm{sup 2})], we demonstrated the utility of our novel methodology by calculating the mineral density of Wistar rats' femur bones.

Jimenez-Mendoza, Daniel; Vargas-Vazquez, Damian [Division de Investigacion y Posgrado, Facultad de Ingenieria, Universidad Autonoma de Queretaro, Cerro de las Campanas s/n., C.P. 76010, Queretaro, Qro. (Mexico); Espinosa-Arbelaez, Diego G. [Posgrado en Ciencia e Ingenieria en Materiales, Instituto de Investigaciones en Materiales, Universidad Nacional Autonoma de Mexico, Av. Universidad 3000, C.P. 04510, Coyoacan, Mexico D.F. (Mexico); Departamento de Nanotecnologia, Centro de Fisica Aplicada y Tecnologia Avanzada, Universidad Nacional Autonoma de Mexico, Campus Juriquilla, Boulevard Juriquilla 3001, C.P. 76230, A.P. 1-1010, Juriquilla, Qro. (Mexico); Giraldo-Betancur, Astrid L. [Centro de Investigacion y de Estudios Avanzados del Instituto Politecnico Nacional, Libramiento Norponiente 2000, C.P. 76230, Fracc. Real de Juriquilla, Qro. (Mexico); Hernandez-Urbiola, Margarita I. [Posgrado en Investigaciones Biomedicas, Universidad Nacional Autonoma de Mexico, Campus Juriquilla, Boulevard Juriquilla 3001, C.P. 76230, A.P. 1-1010, Juriquilla, Qro. (Mexico); Departamento de Nanotecnologia, Centro de Fisica Aplicada y Tecnologia Avanzada, Universidad Nacional Autonoma de Mexico, Campus Juriquilla, Boulevard Juriquilla 3001, C.P. 76230, A.P. 1-1010, Juriquilla, Qro. (Mexico); Rodriguez-Garcia, Mario E. [Departamento de Nanotecnologia, Centro de Fisica Aplicada y Tecnologia Avanzada, Universidad Nacional Autonoma de Mexico, Campus Juriquilla, Boulevard Juriquilla 3001, C.P. 76230, A.P. 1-1010, Juriquilla, Qro. (Mexico)

2011-12-15T23:59:59.000Z

405

X-Ray Diffraction on NIF  

SciTech Connect (OSTI)

The National Ignition Facility (NIF) is currently a 192 beam, 1.6 MJ laser. NIF Ramp-Compression Experiments have already made the relevant exo-planet pressure range from 1 to 50 Mbar accessible. We Proposed to Study Carbon Phases by X-Ray Diffraction on NIF. Just a few years ago, ultra-high pressure phase diagrams for materials were very 'simple'. New experiments and theories point out surprising and decidedly complex behavior at the highest pressures considered. High pressures phases of aluminum are also predicted to be complex. Recent metadynamics survey of carbon proposed a dynamic pathway among multiple phases. We need to develop diagnostics and techniques to explore this new regime of highly compressed matter science. X-Ray Diffraction - Understand the phase diagram/EOS/strength/texture of materials to 10's of Mbar. Strategy and physics goals: (1) Powder diffraction; (2) Begin with diamond; (3) Continue with metals etc.; (4) Explore phase diagrams; (5) Develop liquid diffraction; and (6) Reduce background/improve resolution.

Eggert, J H; Wark, J

2012-02-15T23:59:59.000Z

406

RYLLA. [X-ray transport code  

SciTech Connect (OSTI)

This paper describes a computer code, RYLLA, which models the deposition of x-rays into thin metal slabs, and transports the resulting photoelectrons, finding the distribution of electrons leaving the slab from both the front and back surfaces. The slab must be homogeneous, but can contain a mixture of up to 5 different elements. Due to the short electron mean free path at low electron energies, RYLLA should be used only for studying thin slabs, roughly < 100 mg/cm/sup 2/ for low Z metals, and < 10 mg/cm/sup 2/ for high Z metals. X-ray energies should be in the range of 1 to 150 keV, as they are deposited only via photoionization and Compton scattering processes. Following photoionization, a hole exists in the electron cloud of the absorbing atom. This fills either by Auger or fluoresence, resulting in lower energy holes which are also filled. Fluoresence photons are transported and absorbed in the same manner as the primary photons, except that they are isotropically produced. Once all photons have been transported and absorbed, and all holes have been filled, a space- and energy-dependent electron source spectrum has been obtained. This is used in a discrete ordinate expansion solution of the 1-D transport equation, which gives the output electron spectra at the two slab surfaces. This paper discusses both the physics and coding of RYLLA. Examples of user input are given, as are some comparisons with other codes.

Hyde, R.A.

1983-06-08T23:59:59.000Z

407

Development of procedures for refurbishing x-ray optics at the Advanced Light Source  

E-Print Network [OSTI]

Development of procedures for refurbishing x-ray optics atpractical and robust procedures for refurbishing x-ray

Yashchuk, Valeriy V.

2013-01-01T23:59:59.000Z

408

The variability properties of X-ray steep and X-ray flat quasars  

E-Print Network [OSTI]

We have studied the variability of 6 low redshift, radio quiet `PG' quasars on three timescales (days, weeks, and months) using the ROSAT HRI. The quasars were chosen to lie at the two extreme ends of the ROSAT PSPC spectral index distribution and hence of the H$\\beta$ FWHM distribution. The observation strategy has been carefully designed to provide even sampling on these three basic timescales and to provide a uniform sampling among the quasars We have found clear evidence that the X-ray steep, narrow H_beta, quasars systematically show larger amplitude variations than the X-ray flat broad H_beta quasars on timescales from 2 days to 20 days. On longer timescales we do not find significant differences between steep and flat quasars, although the statistics are poorer. We suggest that the above correlation between variability properties and spectral steepness can be explained in a scenario in which the X-ray steep, narrow line objects are in a higher L/L_Edd state with respect to the X-ray flat, broad line objects. We evaluated the power spectrum of PG1440+356 (the brigthest quasar in our sample) between 2E-7 and 1E-3 Hz, where it goes into the noise. The power spectrum is roughly consistent with a 1/f law between 1E-3 and 2E-6 Hz. Below this frequency it flattens significantly.

Fabrizio Fiore; Ari Laor; Martin Elvis; Fabrizio Nicastro; Emanuele Giallongo

1998-03-20T23:59:59.000Z

409

Application of a Theory for Generation of Soft X-Ray by Storage Rings and Its Use For X-Ray Lithography  

SciTech Connect (OSTI)

A theory has been developed for generation of soft X-ray transition radiation (TR) by storage ring synchrotrons. It takes into consideration that the dielectric constant of the TR target material is a complex number, utilizes an explicit expression for the number of passes of an injected electron through the target, and describes more precisely the absorption of TR in the target. Such TR can be used for performing X-ray lithography (XRL), and therefore a formula is included for the sensitivity of the photoresist used in XRL. TR targets for XRL can be optimized, based on finding a maximum of the resist sensitivity. Application of this theory to optimization of Mg target shows that a target containing only one Mg foil, with a thickness of about 245 nm is the best Mg target, for performing XRL by our storage ring synchrotron MIRRORCLE-20SX.

Minkov, D. [21st Century COE SLLS (Japan); Yamada, H. [21st Century COE SLLS (Japan); Ritsumeikan University (Japan); PPL Co. Ltd., 1-1-1 Nojihigashi, Kusatsu City, Shiga 525-8577 (Japan); Toyosugi, N.; Morita, M. [PPL Co. Ltd., 1-1-1 Nojihigashi, Kusatsu City, Shiga 525-8577 (Japan); Yamaguchi, T. [Ritsumeikan University (Japan)

2007-01-19T23:59:59.000Z

411

Characterization of irradiation-induced precipitates by small angle x-ray and neutron scattering experiments  

SciTech Connect (OSTI)

The nature of the irradiation-induced precipitates in the VVER-440-type steel 15Kh2MFA has been investigated by the combination of small angle neutron scattering and anomalous small angle X-ray scattering. Information about the chemical composition of the irradiation-induced precipitates was obtained by the method of contrast variation. ASAXS experiments with variation of the X-ray energy near the energy of the vanadium K-absorption edge prove the content of vanadium within the irradiation-induced precipitates. The scattering density of the precipitates is lower than the scattering density of the iron matrix. The chemical shift of the vanadium-K{sub {alpha}}-absorption-edge and the results of the variation of the contribution of the magnetic scattering in the SANS experiment show, that vanadium does not precipitate in an elementary state. These results can be explained by assuming the precipitates are vanadium carbide.

Grosse, M.; Eichhorn, F.; Boehmert, J.; Brauer, G. [Research Center Rossendorf Inc., Dresden (Germany)

1996-12-31T23:59:59.000Z

412

Fabrication process for a gradient index x-ray lens  

DOE Patents [OSTI]

A process for fabricating high efficiency x-ray lenses that operate in the 0.5-4.0 keV region suitable for use in biological imaging, surface science, and x-ray lithography of integrated circuits. The gradient index x-ray optics fabrication process broadly involves co-sputtering multi-layers of film on a wire, followed by slicing and mounting on block, and then ion beam thinning to a thickness determined by periodic testing for efficiency. The process enables the fabrication of transmissive gradient index x-ray optics for the 0.5-4.0 keV energy range. This process allows the fabrication of optical elements for the next generation of imaging and x-ray lithography instruments m the soft x-ray region.

Bionta, Richard M. (Livermore, CA); Makowiecki, Daniel M. (Livermore, CA); Skulina, Kenneth M. (Livermore, CA)

1995-01-01T23:59:59.000Z

413

Density gradient free electron collisionally excited X-ray laser  

DOE Patents [OSTI]

An operational X-ray laser (30) is provided that amplifies 3p-3s transition X-ray radiation along an approximately linear path. The X-ray laser (30) is driven by a high power optical laser. The driving line focused optical laser beam (32) illuminates a free-standing thin foil (34) that may be associated with a substrate (36) for improved structural integrity. This illumination produces a generally cylindrically shaped plasma having an essentially uniform electron density and temperature, that exists over a long period of time, and provides the X-ray laser gain medium. The X-ray laser (30) may be driven by more than one optical laser beam (32, 44). The X-ray laser (30) has been successfully demonstrated to function in a series of experimental tests.

Campbell, Edward M. (Pleasanton, CA); Rosen, Mordecai D. (Berkeley, CA)

1989-01-01T23:59:59.000Z

414

Soft x-ray reduction camera for submicron lithography  

DOE Patents [OSTI]

Soft x-ray projection lithography can be performed using x-ray optical components and spherical imaging lenses (mirrors), which form an x-ray reduction camera. The x-ray reduction is capable of projecting a 5x demagnified image of a mask onto a resist coated wafer using 4.5 nm radiation. The diffraction limited resolution of this design is about 135 nm with a depth of field of about 2.8 microns and a field of view of 0.2 cm.sup.2. X-ray reflecting masks (patterned x-ray multilayer mirrors) which are fabricated on thick substrates and can be made relatively distortion free are used, with a laser produced plasma for the source. Higher resolution and/or larger areas are possible by varying the optic figures of the components and source characteristics.

Hawryluk, Andrew M. (2708 Rembrandt Pl., Modesto, CA 95356); Seppala, Lynn G. (7911 Mines Rd., Livermore, CA 94550)

1991-01-01T23:59:59.000Z

415

Soft x-ray reduction camera for submicron lithography  

DOE Patents [OSTI]

Soft x-ray projection lithography can be performed using x-ray optical components and spherical imaging lenses (mirrors), which form an x-ray reduction camera. The x-ray reduction is capable of projecting a 5x demagnified image of a mask onto a resist coated wafer using 4.5 nm radiation. The diffraction limited resolution of this design is about 135 nm with a depth of field of about 2.8 microns and a field of view of 0.2 cm[sup 2]. X-ray reflecting masks (patterned x-ray multilayer mirrors) which are fabricated on thick substrates and can be made relatively distortion free are used, with a laser produced plasma for the source. Higher resolution and/or larger areas are possible by varying the optic figures of the components and source characteristics. 9 figures.

Hawryluk, A.M.; Seppala, L.G.

1991-03-26T23:59:59.000Z

416

Density gradient free electron collisionally excited x-ray laser  

DOE Patents [OSTI]

An operational x-ray laser is provided that amplifies 3p-3s transition x-ray radiation along an approximately linear path. The x-ray laser is driven by a high power optical laser. The driving line focused optical laser beam illuminates a free-standing thin foil that may be associated with a substrate for improved structural integrity. This illumination produces a generally cylindrically shaped plasma having an essentially uniform electron density and temperature, that exists over a long period of time, and provides the x-ray laser gain medium. The x-ray laser may be driven by more than one optical laser beam. The x-ray laser has been successfully demonstrated to function in a series of experimental tests.

Campbell, E.M.; Rosen, M.D.

1984-11-29T23:59:59.000Z

417

Legacy of the X-Ray Laser Program  

SciTech Connect (OSTI)

The X-Ray Laser Program has evolved from a design effort focusing on developing a Strategic Defense Initiative weapon that protects against Soviet ICBMs to a scientific project that is producing new technologies for industrial and medical research. While the great technical successes and failures of the X-ray laser itself cannot be discussed, this article presents the many significant achievements made as part of the X-ray laser effort that are now being used for other applications at LLNL.

Nilsen, J.

1993-08-06T23:59:59.000Z

418

On X-Ray Waveguiding in Nanochannels: Channeling Formalism  

E-Print Network [OSTI]

The question on X-ray extreme focusing (smallest reachable spot size) brings us to the idea for using the wave features of X-ray propagation in media. As known, wave features are revealed at propagation in ultra-narrow collimators as well as at glancing reflection from smooth flat and/or strongly curved surfaces. All these phenomena can be described within the general formalism of X-ray channeling.

S. B. Dabagov

2006-11-20T23:59:59.000Z

419

X-ray Pinhole Camera Measurements  

SciTech Connect (OSTI)

The rod pinch diode is made up of a cathode plate and a small diameter anode rod that extends through the cathode hole. The anode is charged positively. The rod tip is made of a high-z material which is chosen for its bremsstrahlung efficiency. When the diode is pulsed it produces an intense x-ray source used for pulsed radiography. The baseline or reference diode consists of a 0.75 mm diameter Tungsten (W) tapered anode rod which extends 10 mm through a 9 mm diameter 3 mm thick aluminum (Al) aperture. The majority of the current in the electron beam is created on the edges of the cathode aperture and when properly configured, the electrons will self insulate, travel down the extension of the rod, and pinch onto the tip of the rod. In this presentation, performance of hybrid diodes will be compared with the baseline diode.

Nelson, D. S. [NSTec; Berninger, M. J. [NSTec; Flores, P. A. [NSTec; Good, D. E. [NSTec; Henderson, D. J. [NSTec; Hogge, K. W. [NSTec; Huber, S. R. [NSTec; Lutz, S. S. [NSTec; Mitchell, S. E. [NSTec; Howe, R. A. [NSTec; Mitton, C. V. [NSTec; Molina, I. [NSTec; Bozman, D. R. [SNL; Cordova, S. R. [SNL; Mitchell, D. R. [SNL; Oliver, B. V. [SNL; Ormond, E. C. [SNL

2013-06-20T23:59:59.000Z

420

Gray scale x-ray mask  

DOE Patents [OSTI]

The present invention describes a method for fabricating an embossing tool or an x-ray mask tool, providing microstructures that smoothly vary in height from point-to-point in etched substrates, i.e., structure which can vary in all three dimensions. The process uses a lithographic technique to transfer an image pattern in the surface of a silicon wafer by exposing and developing the resist and then etching the silicon substrate. Importantly, the photoresist is variably exposed so that when developed some of the resist layer remains. The remaining undeveloped resist acts as an etchant barrier to the reactive plasma used to etch the silicon substrate and therefore provides the ability etch structures of variable depths.

Morales, Alfredo M. (Livermore, CA); Gonzales, Marcela (Seattle, WA)

2006-03-07T23:59:59.000Z

Note: This page contains sample records for the topic "x-ray absorption fine" 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

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

422

A long-term optical and X-ray ephemeris of the polar EK Ursae Majoris  

E-Print Network [OSTI]

We searched for long-term period changes in the polar EK UMa using new optical data and archival X-ray/EUV data. An optical ephemeris was derived from data taken remotely with the MONET/N telescope and compared with the X-ray ephemeris based on Einstein, Rosat, and EUVE data. A three-parameter fit to the combined data sets yields the epoch, the period, and the phase offset between the optical minima and the X-ray absorption dips. An added quadratic term is insignificant and sets a limit to the period change. The derived linear ephemeris is valid over 30 years and the common optical and X-ray period is P=0.0795440225(24) days. There is no evidence of long-term O-C variations or a period change over the past 17 years Delta P = -0.14+-0.50 ms. We suggest that the observed period is the orbital period and that the system is tightly synchronized. The limit on Delta P and the phase constancy of the bright part of the light curve indicate that O-C variations of the type seen in the polars DP Leo and HU Aqr or the pr...

Beuermann, K; Paik, S; Ploch, A; Zachmann, J; Schwope, A D; Hessman, F V

2009-01-01T23:59:59.000Z

423

SIMULTANEOUS X-RAY AND RADIO OBSERVATIONS OF ROTATING RADIO TRANSIENT J1819-1458  

SciTech Connect (OSTI)

We present the results of simultaneous radio and X-ray observations of PSR J18191458. Our 94 ks XMM-Newton observation of the high magnetic field (?5 10{sup 13} G) pulsar reveals a blackbody spectrum (kT ? 130 eV) with a broad absorption feature, possibly composed of two lines at ?1.0 and ?1.3 keV. We performed a correlation analysis of the X-ray photons with radio pulses detected in 16.2 hr of simultaneous observations at 1-2 GHz with the Green Bank, Effelsberg, and Parkes telescopes, respectively. Both the detected X-ray photons and radio pulses appear to be randomly distributed in time. We find tentative evidence for a correlation between the detected radio pulses and X-ray photons on timescales of less than 10 pulsar spin periods, with the probability of this occurring by chance being 0.46%. This suggests that the physical process producing the radio pulses may also heat the polar-cap.

Miller, J. J.; McLaughlin, M. A. [Department of Physics, West Virginia University, Morgantown, WV 26506 (United States); Rea, N. [Institut de Cincies de l'Espai (IEEC-CSIC) Campus UAB, Fac. de Cincies, Torre C5, parell, 2a planta, E-08193 Barcelona (Spain); Lazaridis, K.; Keane, E. F.; Kramer, M. [Max Planck Institut fr Radioastronomie, Auf dem Hgel 69, D-53121 Bonn (Germany); Lyne, A. [Jodrell Bank Centre for Astrophysics, School of Physics and Astronomy, University of Manchester, Manchester M13 9PL (United Kingdom)

2013-10-20T23:59:59.000Z

424

X-ray Emission from the Weak-lined T Tauri Binary System KH 15D  

E-Print Network [OSTI]

The unique eclipsing, weak-lined T Tauri star KH 15D has been detected as an X-ray source in a 95.7 ks exposure from the Chandra X-ray Observatory archives. A maximum X-ray luminosity of 1.5 x 10^{29} erg s$^{-1}$ is derived in the 0.5--8 keV band, corresponding to L_{X}/L_bol = 7.5 x 10^{-5}. Comparison with samples of stars of similar effective temperature in NGC 2264 and in the Orion Nebula Cluster shows that this is about an order of magnitude low for a typical star of its mass and age. We argue that the relatively low luminosity cannot be attributed to absorption along the line of sight but implies a real deficiency in X-ray production. Possible causes for this are considered in the context of a recently proposed eccentric binary model for KH 15D. In particular, we note that the visible component rotates rather slowly for a weak-lined T Tauri star and has possibly been pseudosynchronized by tidal interaction with the primary near periastron.

William Herbst; Edward C. Moran

2005-06-08T23:59:59.000Z

425

X-Ray Observations of the Sagittarius D HII Region toward the Galactic Center with Suzaku  

E-Print Network [OSTI]

We present a Suzaku X-ray study of the Sagittarius D (Sgr D) HII region in the Galactic center region. Two 18'x18' images by the X-ray Imaging Spectrometer (XIS) encompass the entire Sgr D complex. Thanks to the low background, XIS discovered two diffuse sources with low surface brightness and obtained their high signal-to-noise ratio spectra. One is associated with the core of the Sgr D HII region, arising from the young stellar cluster. The other is a new object in the vicinity of the region. We also present 3.5 cm and 6.0 cm radio continuum maps of the new source using the 100 m Green Bank Telescope. We conclude that the source is a new supernova remnant (SNR; G1.2--0.0) based on: (1) the 0.9+/-0.2 keV thermal X-ray spectrum with emission lines from highly ionized atoms; (2) the diffuse nature with an apparent extent of ~10 pc at the Galactic center distance inferred from the X-ray absorption (~8.5x10^{22} cm^{-2}); and (3) the nonthermal radio continuum spectral index (~-0.5). Our discovery of an SNR in the Sgr D HII region leads to a revision of the view of this system, which had been considered to be a thermal HII region and its environment.

Makoto Sawada; Masahiro Tsujimoto; Katsuji Koyama; Casey J. Law; Takeshi Go Tsuru; Yoshiaki Hyodo

2008-05-14T23:59:59.000Z

426

THE CORRELATION BETWEEN DISPERSION MEASURE AND X-RAY COLUMN DENSITY FROM RADIO PULSARS  

SciTech Connect (OSTI)

Pulsars are remarkable objects that emit across the entire electromagnetic spectrum, providing a powerful probe of the interstellar medium. In this study, we investigate the relation between dispersion measure (DM) and X-ray absorption column density N{sub H} using 68 radio pulsars detected at X-ray energies with the Chandra X-Ray Observatory or XMM-Newton. We find a best-fit empirical linear relation of N{sub H} (10{sup 20} cm{sup -2})= 0.30{sup +0.13}{sub -0.09} DM (pc cm{sup -3}), which corresponds to an average ionization of 10{sup +4}{sub -3}%, confirming the ratio of one free electron per 10 neutral hydrogen atoms commonly assumed in the literature. We also compare different N{sub H} estimates and note that some N{sub H} values obtained from X-ray observations are higher than the total Galactic H I column density along the same line of sight, while the optical extinction generally gives the best N{sub H} predictions.

He, C.; Ng, C.-Y.; Kaspi, V. M., E-mail: ncy@bohr.physics.hku.hk [Department of Physics, McGill University, Montreal, QC H3A 2T8 (Canada)

2013-05-01T23:59:59.000Z

427

A laser triggered vacuum spark x-ray lithography source  

E-Print Network [OSTI]

ionized state or the physical processes occurring 15 in a high temperature plasma. There are many advantages to the use of the vacuum spark as an x-ray source; the simplicity of the machine is one. The x-ray output is within the range usable for x-ray... spark apparatus ha- been studied here to determine its applicability to x-ray lithography. A capacitor which stored approximately 3 KJ supplied most of the energy for the plasma. A Nd-YAG laser was used to supply electrons and metallic atoms...

Keating, Richard Allen

1987-01-01T23:59:59.000Z

428

Unexpected Angular Dependence of X-Ray Magnetic Linear Dichroism  

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

axes must be taken into account for accurate interpretation of XMLD data. Magnetism and X Rays The ancient Greeks and also the Chinese knew about strange and rare...

429

Refractive Optics for Hard X-ray Transmission Microscopy  

SciTech Connect (OSTI)

For hard x-ray transmission microscopy at photon energies higher than 15 keV we design refractive condenser and imaging elements to be used with synchrotron light sources as well as with x-ray tube sources. The condenser lenses are optimized for low x-ray attenuation--resulting in apertures greater than 1 mm--and homogeneous intensity distribution on the detector plane, whereas the imaging enables high-resolution (<100 nm) full-field imaging. To obtain high image quality at reasonable exposure times, custom-tailored matched pairs of condenser and imaging lenses are being developed. The imaging lenses (compound refractive lenses, CRLs) are made of SU-8 negative resist by deep x-ray lithography. SU-8 shows high radiation stability. The fabrication technique enables high-quality lens structures regarding surface roughness and arrangement precision with arbitrary 2D geometry. To provide point foci, crossed pairs of lenses are used. Condenser lenses have been made utilizing deep x-ray lithographic patterning of thick SU-8 layers, too, whereas in this case, the aperture is limited due to process restrictions. Thus, in terms of large apertures, condenser lenses made of structured and rolled polyimide film are more attractive. Both condenser types, x-ray mosaic lenses and rolled x-ray prism lenses (RXPLs), are considered to be implemented into a microscope setup. The x-ray optical elements mentioned above are characterized with synchrotron radiation and x-ray laboratory sources, respectively.

Simon, M.; Last, A.; Mohr, J.; Nazmov, V.; Reznikova, E. [Institute for Microstructure Technology, Karlsruhe Institute of Technology Kaiserstrasse 12, 76131 Karlsruhe (Germany); Ahrens, G.; Voigt, A. [Microresist Technology, Koepenikerstrasse 325, 12555 Berlin (Germany)

2011-09-09T23:59:59.000Z

430

Normal incidence x-ray mirror for chemical microanalysis  

DOE Patents [OSTI]

An x-ray mirror for both electron column instruments and micro x-ray fluorescence instruments for making chemical, microanalysis comprises a non-planar mirror having, for example, a spherical reflecting surface for x-rays comprised of a predetermined number of alternating layers of high atomic number material and low atomic number material contiguously formed on a substrate and whose layers have a thickness which is a multiple of the wavelength being reflected. For electron column instruments, the wavelengths of interest lie above 1.5nm, while for x-ray fluorescence instruments, the range of interest is below 0.2nm. 4 figs.

Carr, M.J.; Romig, A.D. Jr.

1987-08-05T23:59:59.000Z

431

Fuel Injection and Spray Research Using X-Ray Diagnostics  

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

collaborations - Explore new capabilities, applications Upgraded x-ray optics in FY2011 - Allows us to resolve finer structures in spray * Old beamline: 150 m x...

432

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...

433

X-ray laser system, x-ray laser and method  

DOE Patents [OSTI]

Disclosed is an x-ray laser system comprising a laser containing generating means for emitting short wave length radiation, and means external to said laser for energizing said generating means, wherein when the laser is in an operative mode emitting radiation, the radiation has a transverse coherence length to width ratio of from about 0.05 to 1. Also disclosed is a method of adjusting the parameters of the laser to achieve the desired coherence length to laser width ratio.

London, Richard A. (Oakland, CA); Rosen, Mordecai D. (Berkeley, CA); Strauss, Moshe (Omer, IL)

1992-01-01T23:59:59.000Z

434

The XMM-Newton Wide Angle Survey (XWAS): the X-ray spectrum of type-1 AGN  

E-Print Network [OSTI]

We discuss the broad band X-ray properties of one of the largest samples of X-ray selected type-1 AGN to date (487 objects in total), drawn from the XMM-Newton Wide Angle Survey. The objects cover 2-10 keV luminosities from ~10^{42}-10^{45} erg s^{-1} and are detected up to redshift ~4. We constrain the overall properties of the broad band continuum, soft excess and X-ray absorption, along with their dependence on the X-ray luminosity and redshift and we discuss the implications for models of AGN emission. We constrained the mean spectral index of the broad band X-ray continuum to =1.96+-0.02 with intrinsic dispersion sigma=0.27_{-0.02}^{+0.01}. The continuum becomes harder at faint fluxes and at higher redshifts and luminosities. The dependence of Gamma with flux is likely due to undetected absorption rather than to spectral variation. We found a strong dependence of the detection efficiency of objects on the spectral shape which can have a strong impact on the measured mean continuum shapes of sources at di...

Mateos, S; Page, M J; Watson, M G; Corral, A; Tedds, J A; Ebrero, J; Krumpe, M; Schwope, A; Ceballos, M T

2009-01-01T23:59:59.000Z

435

Constraints on jet X-ray emission in low/hard state X-ray binaries  

E-Print Network [OSTI]

We show that the combination of the similarities between the X-ray properties of low luminosity accreting black holes and accreting neutron stars, combined with the differences in their radio properties argues that the X-rays from these systems are unlikely to be formed in the relativistic jets. Specifically, the spectra of extreme island state neutron stars and low/hard state black holes are known to be indistinguishable, while the power spectra from these systems are known to show only minor differences beyond what would be expected from scaling the characteristic variability frequencies by the mass of the compact object. The spectral and temporal similarities thus imply a common emission mechanism that has only minor deviations from having all key parameters scaling linearly with the mass of the compact object, while we show that this is inconsistent with the observations that the radio powers of neutron stars are typically about 30 times lower than those of black holes at the same X-ray luminosity. We also show that an abrupt luminosity change would be expected when a system makes a spectral state transition from a radiatively inefficient jet dominated accretion flow to a thin disk dominated flow, but that such a change is not seen.

Thomas J. Maccarone

2005-03-31T23:59:59.000Z

436

Isotropic star in low-mass X-ray binaries and X-ray pulsars  

E-Print Network [OSTI]

We present a model for compact stars in the low mass X-ray binaries(LMXBs) and X-ray pulsars using a metric given by John J. Matese and Patrick G. Whitman \\citep{Matese and Whitman1980}. Here the field equations are reduced to a system of two algebraic equations considering the isotropic pressure. Compact star candidates 4U 1820-30(radius=10km) in LMXBs, and Her X-1(radius=7.7km), SAX J 1808.4-3658(SS1)(radius=7.07km) and SAX J 1808.4-3658(SS2)(radius=6.35km) in X-ray pulsars satisfy all the energy conditions, TOV-equation and stability condition. From our model, we have derived mass($M$), central density($\\rho_{0}$), suface density($\\rho_{b}$), central pressure($p_{0}$), surface pressure($p_{b}$) and surface red-shift($Z_{s}$) of the above mentioned stars, which are very much consistant with the observed/reported datas\\citep{N. K. Glendenning1997,Gondek2000}. We have also observe the adiabatic index($\\gamma$>4/3) of the above steller objects.

Mehedi Kalam; Sk. Monowar Hossein; Sajahan Molla

2014-10-01T23:59:59.000Z

437

Green's functions for transmission of X-rays and gamma-rays through cold media  

E-Print Network [OSTI]

Using a Monte Carlo method, we study Compton scattering and absorption of X-rays and gamma-rays in cold media. We consider transmission of X/gamma-rays through a shell of an arbitrary optical depth, for which we derive energy-dependent Green's functions. Fitting the Green functions with simple analytical formulae is in progress. We also present a simple treatment of the effect of absorption on Green's functions for Compton scattering, which allow to treat media with an arbitrary ionization state and chemical composition. Our transmission Green's functions allow to treat Thomson-thick absorbers, e.g. molecular tori of Seyfert 2s.

P. Magdziarz; A. A. Zdziarski

1996-07-03T23:59:59.000Z

438

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

439

X-ray spectra transmitted through Compton-thick absorbers  

E-Print Network [OSTI]

X-ray spectra transmitted through matter which is optically thick to Compton scattering are computed by means of Monte Carlo simulations. Applications to the BeppoSAX data of the Seyfert 2 galaxy in Circinus, and to the spectral modeling of the Cosmic X-ray Background, are discussed.

Giorgio Matt; Fulvio Pompilio; Fabio La Franca

1999-04-24T23:59:59.000Z

440

Measurement and characterization of x-ray spot size  

SciTech Connect (OSTI)

In planning an x-ray imaging experiment one must have an accurate model of the imaging system to obtain optimum results. The blurring caused by the finite size of the x-ray source is often the least understood element in the system. We have developed experimental and analytical methods permitting accurate measurement and modeling of the x-ray source. The model offers a simple and accurate way to optimize the radiographic geometry for any given experimental requirement (i.e., resolution and dose at detector). Any text on radiography will mention the effects of the finite size of the x-ray source on image quality and how one can minimize this influence by the choice of a small radiographic magnification. The film blur (independent of the source blur) is often treated as a single number and combined with an effective blur dimension for the x-ray source to give a total blur on the film. In this paper, we will develop a treatment of x-ray sources based on the modulation transfer function (MTF). This approach allows us to infer the spatial distribution function of the electron beam that produces the bremsstrahlung x-rays and to predict the performance of an x-ray imaging system if we know the MTF of the detector. This treatment is much more accurate than a single number characterization. 4 refs., 7 figs.

Mueller, K.H.

1989-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "x-ray absorption fine" from the National Library of EnergyBeta (NLEBeta).
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441

High resolution energy-sensitive digital X-ray  

DOE Patents [OSTI]

An apparatus and method for detecting an x-ray and for determining the depth of penetration of an x-ray into a semiconductor strip detector. In one embodiment, a semiconductor strip detector formed of semiconductor material is disposed in an edge-on orientation towards an x-ray source such that x-rays From the x-ray source are incident upon and substantially perpendicular to the front edge of the semiconductor strip detector. The semiconductor strip detector is formed of a plurality of segments. The segments are coupled together in a collinear arrangement such that the semiconductor strip detector has a length great enough such that substantially all of the x-rays incident on the front edge of the semiconductor strip detector interact with the semiconductor material which forms the semiconductor strip detector. A plurality of electrodes are connected to the semiconductor strip detect or such that each one of the of semiconductor strip detector segments has at least one of the of electrodes coupled thereto. A signal processor is also coupled to each one of the electrodes. The present detector detects an interaction within the semiconductor strip detector, between an x-ray and the semiconductor material, and also indicates the depth of penetration of the x-ray into the semiconductor strip detector at the time of the interaction.

Nygren, David R. (Berkeley, CA)

1995-01-01T23:59:59.000Z

442

Human genome sequencing with direct x-ray holographic imaging  

SciTech Connect (OSTI)

Direct holographic imaging of biological materials is widely applicable to the study of the structure, properties and action of genetic material. This particular application involves the sequencing of the human genome where prospective genomic imaging technology is composed of three subtechnologies, name an x-ray holographic camera, suitable chemistry and enzymology for the preparation of tagged DNA samples, and the illuminator in the form of an x-ray laser. We report appropriate x-ray camera, embodied by the instrument developed by MCR, is available and that suitable chemical and enzymatic procedures exist for the preparation of the necessary tagged DNA strands. Concerning the future development of the x-ray illuminator. We find that a practical small scale x-ray light source is indeed feasible. This outcome requires the use of unconventional physical processes in order to achieve the necessary power-compression in the amplifying medium. The understanding of these new physical mechanisms is developing rapidly. Importantly, although the x-ray source does not currently exist, the understanding of these new physical mechanisms is developing rapidly and the research has established the basic scaling laws that will determine the properties of the x-ray illuminator. When this x-ray source becomes available, an extremely rapid and cost effective instrument for 3-D imaging of biological materials can be applied to a wide range of biological structural assays, including the base-pair sequencing of the human genome and many questions regarding its higher levels of organization.

Rhodes, C.K.

1993-06-08T23:59:59.000Z

443

Electromagnetic Application: X-RAY Alawi H. Ba-Surrah  

E-Print Network [OSTI]

, Pulyui published high-quality x-ray images in journals in Paris and London. · Nikola Tesla In April 1887, Nikola Tesla began to investigate X-rays using high voltages and tubes of his own design, as well. The principle behind Tesla's device is called the Bremsstrahlung process, in which a high-energy secondary X

Masoudi, Husain M.

444

Thirteenth National School on Neutron and X-ray Scattering  

E-Print Network [OSTI]

Thirteenth National School on Neutron and X-ray Scattering June 11 ­ June 25, 2011 at Argonne of the National School on Neutron and X-ray Scattering is to educate graduate students on the utilization of major National Laboratory's Neutron Scattering Science Division. Scientific Directors: Jonathan C. Lang, Suzanne

445

Neutron and X-ray Scattering Study of Magnetic Manganites  

E-Print Network [OSTI]

Neutron and X-ray Scattering Study of Magnetic Manganites Graeme Eoin Johnstone A Thesis submitted are performed using a variety of neutron scattering and x-ray scattering techniques. The electronic ground for analysing the results of the polarised neutron scattering experiment. There are a large number of people who

Boothroyd, Andrew

446

Tenth National School on Neutron and X-ray Scattering  

E-Print Network [OSTI]

Tenth National School on Neutron and X-ray Scattering September 24 - October 11, 2008 at Argonne of the National School on Neutron and X-ray Scattering is to educate graduate students on the utilization of major National Laboratory's Neutron Scattering Science Division. Scientific Directors: Jonathan C. Lang, Suzanne

Pennycook, Steve

447

Sixteenth National School on Neutron and X-ray Scattering  

E-Print Network [OSTI]

Sixteenth National School on Neutron and X-ray Scattering June 14-28, 2014 at Argonne National of the National School on Neutron and X-ray Scattering is to educate graduate students on the utilization of major's Neutron Scattering Science Division. Scientific Directors: Suzanne G.E. te Velthuis, Esen Ercan Alp

Pennycook, Steve

448

Fourteenth National School on Neutron and X-ray Scattering  

E-Print Network [OSTI]

Fourteenth National School on Neutron and X-ray Scattering August 12 - 25, 2012 at Argonne National of the National School on Neutron and X-ray Scattering is to educate graduate students on the utilization of major Ridge National Laboratory's Neutron Scattering Science Division. Scientific Directors: Jonathan C. Lang

Pennycook, Steve

449

National School on Neutron and X-ray Scattering  

E-Print Network [OSTI]

15th National School on Neutron and X-ray Scattering August 10 - 24, 2013 at Argonne National of the National School on Neutron and X-ray Scattering is to educate graduate students on the utilization of major Ridge National Laboratory's Neutron Scattering Science Division. Scientific Directors: Jonathan C. Lang

450

National School on Neutron and X-ray Scattering  

E-Print Network [OSTI]

National School on Neutron and X-ray Scattering May 30 ­ June 13, 2009 at Argonne National of the National School on Neutron and X-ray Scattering is to educate graduate students on the utilization of major National Laboratory's Neutron Scattering Science Division. Scientific Directors: Jonathan C. Lang, Suzanne

Pennycook, Steve

451

Twelfth National School on Neutron and X-ray Scattering  

E-Print Network [OSTI]

Twelfth National School on Neutron and X-ray Scattering June 12 ­ June 26, 2010 at Argonne National of the National School on Neutron and X-ray Scattering is to educate graduate students on the utilization of major National Laboratory's Neutron Scattering Science Division. Scientific Directors: Jonathan C. Lang, Suzanne

Pennycook, Steve

452

Ultrafast x-rays: radiographing magnetism Project overview  

E-Print Network [OSTI]

, head of the ultrafast magnetism group. Stanford PULSE is a worldwide renowned centre for ultrafast1 Ultrafast x-rays: radiographing magnetism Project overview The main purpose of the proposed, it is now possible to achieve x-ray pulses that are a few femtoseconds long and that are focused within

Haviland, David

453

Laser Copper Plasma X-ray Source Debris Characterization  

E-Print Network [OSTI]

Laser Copper Plasma X-ray Source Debris Characterization A Thesis Presented by David Hurley 3, 2007 Vice President for Research and Dean of Graduate studies #12;Abstract Laser copper plasma for x-ray lithography. Copper debris in the form of vapor, ions, dust, and high-speed particles

Huston, Dryver R.

454

Millisecond oscillations during thermonuclear X-ray bursts  

E-Print Network [OSTI]

I analyze 68 oscillation trains detected in a search of 159 thermonuclear bursts from eight neutron star X-ray binaries observed with the Rossi X-ray Timing Explorer. I use all data that were public as of September 2001. ...

Muno, Michael Patrick, 1975-

2002-01-01T23:59:59.000Z

455

Chandra X-ray Analysis of Galaxy Cluster A168  

E-Print Network [OSTI]

We present Chandra X-ray observations of galaxy cluster A168 (z=0.045). Two X-ray peaks with a projected distance of 676 kpc are found to be located close to two dominant galaxies, respectively. Both peaks are significantly offset from the peak of the number density distribution of galaxies. This suggests that A168 consists of two subclusters, a northern subcluster (A168N) and a southern subcluster (A168S). Further X-ray imaging analysis reveals that (1) the X-ray isophotes surrounding the two X-ray peaks are heavily distorted, (2) an elongated and ontinuous filament connects the two X-ray peaks. These suggest that strong interactions have occurred between the two subclusters. Spectral analysis shows that A168 has a mean temperature of 2.53 +/- 0.09 keV and a mean metallicity of 0.31 +/- 0.04 Z_{solar}. The metallicity is roughly a constant across the cluster but the temperature shows some systematic variations. Most X-ray, optical and radio properties of A168 are consistent with it being an off-axis merger several Gyrs after a core passage, although detailed numerical simulations are required to see whether the observed properties, in particular the significant offset between the optical and X-ray centers, can be reproduced in such a scenario.

Yanbin Yang; Zhiying Huo; Xu Zhou; Suijian Xue; Shude Mao; Jun Ma; Jiansheng Chen

2004-06-29T23:59:59.000Z

456

X-Ray Observations of Gamma-Ray Burst Afterglows  

E-Print Network [OSTI]

The discovery by the BeppoSAX satellite of X-ray afterglow emission from the gamma-ray burst which occurred on 28 February 1997 produced a revolution in our knowledge of the gamma-ray burst phenomenon. Along with the discovery of X-ray afterglows, the optical afterglows of gamma-ray bursts were discovered and the distance issue was settled, at least for long $\\gamma$-ray bursts. The 30 year mystery of the gamma-ray burst phenomenon is now on the way to solution. Here I rewiew the observational status of the X-ray afterglow emission, its mean properties (detection rate, continuum spectra, line features, and light curves), and the X-ray constraints on theoretical models of gamma-ray bursters and their progenitors. I also discuss the early onset afterglow emission, the remaining questions, and the role of future X-ray afterglow observations.

Filippo Frontera

2004-06-25T23:59:59.000Z

457

X-ray intensity interferometer for undulator radiation  

SciTech Connect (OSTI)

Intensity interferometry is well established with visible light but has never been demonstrated with x-radiation. We propose to measure the transverse coherence of an x-ray beam, for the first time, using the method of Hanbury Brown and Twiss. The x-ray interferometer consists of an array of slits, a grazing incidence reflective beamsplitter, a pair of fast multichannel plate detectors and a broadband, low-noise correlator circuit. The NSLS X1 or X13 soft x-ray undulator will supply the partially coherent x-rays. We are developing this technique to characterize the coherence properties of x-ray beams from high brilliance insertion devices at third-generation synchrotron light facilities such as the Advanced Photon Source and the Advanced Light Source. 17 refs.

Gluskin, E.; McNulty, I.; Viccaro, P.J. [Argonne National Lab., IL (United States); Howells, M.R. [Lawrence Berkeley Lab., CA (United States)

1991-12-31T23:59:59.000Z