An experimental and theoretical study of the K absorption pre-edge in hematite ({alpha}-Fe2O3) is presented. Resonant inelastic X-ray scattering with a 3p hole in the final states was used to obtain spin-selective absorption spectra. Spectral variations with changing the orientation of the incident X-ray polarization vector with ...

A study of the Mn K absorption pre-edges in oxides using resonant inelastic X-ray scattering (RIXS) spectroscopy is presented. The energy transfer dimension enhances the separation of the pre-edge (predominantly 1s to 3d transitions) from the main K-edge and a detailed analysis is thus possible. The RIXS spectra are sensitive to the Mn spin state. The ...

This article describes the use of synchrotron radiation to study chemical and structural changes of catalysts during actual operating conditions. Described are techniques using x-ray absorption near edge structure, extended x-ray absorption fine structure, pre-edge x-ray ...

The sensitivity of polarized Fe K-edge XANES spectra to Fe-C-O geometry is investigated in carbonmonoxy-myoglobin (MbCO) using first-principles non ``muffin-tin'' calculations. Structures issued from the Protein Data Bank (PDB) are optimized using Car-Parrinello dynamics and compared to experiment through simulations of X-ray absorption spectra. In order ...

Strontium titanate exhibits two phase transitions at 5 GPa and 14 GPa. We use X-ray absorption Ti K pre-edge structure as a probe of the local atomic structure of SrTiO3 under pressure. The pre-edge is characterized by four main features labeled A, B, C1 and C2. Above 5 GPa, the intensity of peak B is decreased ...

in situ glancing-angle x-ray reflectivity experiments were performed on electrochemical reduction products formed in a dilute paramolybdate solution on a platinum electrode. These data were compared with x-ray photoelectron spectra which showed formation of simple molybdate, pentavalent and tetravalent species at increasingly negative potentials. X-ray absorption data ...

in situ glancing-angle x-ray reflectivity experiments were performed on electrochemical reduction products formed in a dilute paramolybdate solution on a platinum electrode. These data were compared with x-ray photoelectron spectra which showed formation of simple molybdate, pentavalent and tetravalent species at increasingly negative potentials. X-ray absorption data ...

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 ...

The electronic structures of HgII, NiII, CrIII, and MoV 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 ...

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 ...

Pre-edge spectral features below the main X-ray absorption K-edge of transition metals show a pronounced chemical sensitivity and are promising sources of structural information. Nevertheless, the use of pre-edge analysis in applied research is limited because of the lack of definite theoretical peak-assignments. The aim of this study ...

In addition to probing the formation of dinitrosyl iron complexes (DNICs) by the characteristic Fe K-edge pre-edge absorption energy ranging from 7113.4 to 7113.8 eV, the distinct S K-edge pre-edge absorption energy and pattern can serve as an efficient tool to unambiguously characterize and discriminate ...

Initial results are reported on a new microprobe technique for determining Fe{sup 3+}/{Sigma}Fe ratios in Fe-bearing minerals. The technique is based on the energy shift of a pre-edge peak in X-ray absorption near-edge structure (XANES) spectra obtained using the synchrotron X-ray fluorescence microprobe. A linear relationship between ...

We have investigated the nature of the residual damage in diamond crystals following the ion implantation/graphitization ``lift-off'' process, using near-edge x-ray absorption fine structure spectroscopy and transmission electron microscopy. A defective but crystalline interface is found, which displays dense pre-edge unoccupied states ...

We report the high-pressure measurement of the FeK edge in hematite (Fe2O3) by x-ray absorption spectroscopy in partial fluorescence yield geometry. The pressure-induced evolution of the electronic structure as Fe2O3 transforms from a high-spin insulator to a low-spin metal is reflected in the x-ray absorption ...

The lifetime broadening of some rare-earth {ital L}{sub III}-edge x-ray absorption spectra (XAS) is partially removed by deconvolving high quality data. The ligand field splitting of dipolar resonances is clearly resolved. Exposed pre-edge structure is compared to atomic multiplet calculations of the 2{ital p}{r_arrow}4{ital f} ...

Fe K-edge and Se K-edge x-ray absorption near edge structure (XANES) measurements are used to study the FeSe1 ? xTex electronic structure of chalcogenides. An intense Fe K-edge pre-edge peak due to Fe 1\\mathrm {s}\\to 3\\rmd (and admixed Se/Te p states) is observed, showing substantial change with Te substitution ...

Fe K-edge and Se K-edge x-ray absorption near edge structure (XANES) measurements are used to study the FeSe(1 - x)Te(x) electronic structure of chalcogenides. An intense Fe K-edge pre-edge peak due to Fe 1s --> 3d (and admixed Se/Te p states) is observed, showing substantial change with Te substitution and ...

We have performed Time Dependent Density Functional Theory (TDDFT) calculations employing a cluster model of the core excitation spectra of vanadium pentoxide, V(2)O(5). The excitation energies and dipole transition moments are determined for all the core edges, vanadium and oxygen K- and vanadium L-edges, treating them at the same level of accuracy. The agreement between the TDDFT theoretical ...

The dinuclear iron center of the hydroxylase component of soluble methane monooxygenase (MMO) from Methylococcus capsulatus (Bath) and Methylosinus trichosporium (OB3b) has been studied by X-ray absorption spectroscopy. Analysis of the Fe K-edge EXAFS revealed that the first shell coordination of the hydroxylase consists of [approximately]6 N and O atoms at an average distance ...

X-ray diffraction and vanadium x-ray absorption near-edge structure (XANES) data have been obtained for (V1-xCrx)2O3 samples containing several concentrations of Cr, crossing the metal-insulator transition boundary. For single-phase single-crystal samples our theoretical results are generally in good qualitative agreement with our experimental ...

A K? satellite peak in X-ray fluorescence (XRF) spectra is observed as a counterpart of the pre-edge peak of the X-ray absorption near edge structure (XANES). In K? emission of chromium, a small satellite peak is observed at 5.983-5.988 keV only for hexavalent chromium compounds such as CrO(3), Na(2)CrO(7)�2H(2)O, Na(2)CrO(4)�4H(2)O, K(2)Cr(2)O(7), ...

The technique of transmission high-energy electron energy loss spectrometry (EELS) in TEM has been applied to analyze the formation of charge carriers (holes) and charge transfer in p-type doped cuprate superconductors. The O-K absorption edges of these compounds exhibit a distinct pre-edge feature which is related to the formation of holes on oxygen ...

We have made significant improvements in pump-probe time-resolved X-ray absorption spectroscopy that enable us to structurally describe chemical intermediates with short lifetimes. We demonstrate that X-ray pre-edge data for a 1 mM compound can be acquired with a high signal-to-noise ratio by time-resolved discrimination of fluorescent ...

Fe-K edge XAFS spectra (pre-edge, XANES and EXAFS) were collected for eight grandidierites from Madagascar and Zimbabwe, as well as for Fe(II) and Fe(III) model compounds (staurolite, siderite, enstatite, berlinite, yoderite, acmite, and andradite). The pre-edge spectra for these samples are consistent with dominantly 5-coordinated ferrous iron. The analysis of the XANES and ...

This chapter is devoted to explaining the foundation and merits of the application of synchrotron radiation for studying the X-ray absorption fine structure (XAFS) in ferroelectric materials. XAFS in the local order allows the follows: determining the oxidation states, interatomic distances, Debye-Waller factors and the coordination number of atoms at the ...

We analyze the vibrational effects on the Ti 1s excited states in cubic SrTiO3 and related pre-edge x-ray absorption fine structure using first-principles methods. Ground-state, total-energy and electron-core hole Bethe-Salpeter calculations are performed for different atomic configurations related to eg-symmetry distortions of SrTiO3. ...

C1 K-edge X-ray absorption spectra were measured for concentrated ferric chloride solutions. A single pre-edge XANES feature due to transitions to metal 3d derived orbitals depends on concentration according to the degree of direct Fe2+ C1 bonding. Fourie...

The angular dependence (x-ray linear dichroism) of the CrK pre-edge in MgAl2O4:Cr3+ spinel is measured by means of x-ray absorption near-edge structure spectroscopy and compared to calculations based on density functional theory (DFT) and ligand field multiplet (LFM) theory. We also present an efficient method, based on symmetry ...

Co K-edge X-ray absorption near-edge spectra at 300K and magnetic studies for the rhombohedral LaCoO3 with low-spin state to intermediate-spin (IS) state transition Ts~=105K and orthorhombic EuCoO3(Ts~=295K) are reported. The small pre-edge feature observed is from 1s-3d dipole transition, which is weakly allowed through the hybridization of Co 4p states ...

For the first time a method has been developed for the extended X-ray absorption fine structure (EXAFS) data analyses of biological samples containing multiple oxidation states of chromium. In this study, the first shell coordination and interatomic distances based on the data analysis of known standards of potassium chromate (Cr(VI)) and chromium nitrate ...

For the first time a method has been developed for the extended X-ray absorption fine structure (EXAFS) data analyses of biological samples containing multiple oxidation states of chromium. In this study, the first shell coordination and interatomic distances based on the data analysis of known standards of potassium chromate (Cr(VI)) and chromium nitrate ...

The 3d transition-metal diborides TiB2, VB2 and CrB2 have been characterized by X-ray absorption near-edge-structure (XANES) spectroscopy at the metal K edges. XANES spectra at the Ti, V and Cr K-edges of TiB2, VB2 and CrB2, respectively, show similar spectral features up to an energy of about 70 eV above threshold. These features can be correlated to ...

We describe the use of Cl K-edge X-ray absorption spectroscopy (XAS) and both ground-state and time-dependent hybrid density functional theory (DFT) to probe the electronic structure and determine the degree of orbital mixing in M-Cl bonds for (C(5)Me(5))(2)MCl(2) (M = Ti, 1; Zr, 2; Hf, 3; Th, 4; U, 5), where we can directly compare a class of ...

Electronic and structural aspects of a MnO{sub 2} electrode in a rechargeable MnO{sub 2}/Zn battery environment have been investigated by in situ Mn K-edge x-ray absorption fine structure (XAFS). The relative amplitudes of the three major Fourier transform shells of the extended XAFS function of the rechargeable MnO{sub 2} electrode in ...

Electronic and structural aspects of a MnO{sub 2} electrode in a rechargeable MnO{sub 2}/Zn battery environment have been investigated by in situ Mn K-edge X-ray absorption fine structure (XAFS). The relative amplitudes of the three major Fourier transform shells of the EXAFS (extended XAFS) function of the rechargeable MnO{sub 2} ...

A promising proxy for oxygen fugacity is the valence of vanadium because it has a large number of possible states (2+, 3+, 4+ and 5+) and is ubiquitous in earth and planetary materials. A non-destructive method for valence determinations of vanadium and oxygen fugacity estimates with spatial resolution of a few micrometers is synchrotron x-ray absorption near edge ...

Coordination complexes of vanadium(5+) played a key role in understanding the structure and mechanism of vanadium-dependent haloperoxidases, particularly the effects of protonation on peroxide coordination to dioxovanadium(5+) species, and in the activation of the peroxo-oxovanadium(5+) complex for substrate oxidation. There has been no spectroscopic evidence that could test ...

The hole distribution of overdoped, optimum-doped and underdoped states in the series Bi{sub 2}Sr{sub 2}(Ca{sub 1{minus}x}Y{sub x})Cu{sub 2}O{sub 8+{delta}} compounds has been investigated by high-resolution O K-edge and Cu L-edge X-ray absorption near-edge-structure (XANES) spectra. Near the O 1s edge, a well-pronounced pre-edge peak ...

Electronic and structural aspects of vanadium-substituted heteropolytungstates immobilized in a high-area carbon (XC-72) as a function of oxidation state have been examined by in situ X-ray absorption near-edge structure (XANES) in an acidic electrolyte. The results obtained for K{sub 4}PVW{sub 11}O{sub 40} revealed a sizable shift in ...

The behavior of cubic ZrW{sub 2}O{sub 8} on compression in a DAC to 7.6 GPa was examined in situ by a combination of synchrotron x-ray diffraction and x-ray absorption spectroscopy (XAS). These data were compared with x-ray absorption measurements on an amorphous sample of ZrW{sub 2}O{sub 8} recovered from 7.5 GPa in a multianvil apparatus. The in situ ...

The temperature-dependent X-ray absorption near-edge spectroscopy (XANES) of LaMnO3 thin films doped with various divalent ions was systematically carried out to investigate the effects of the ion size and associated Jahn-Teller distortions (JTDs) on the electronic structure modifications. Doped LaMnO3 thin films were grown on (1 0 0) SrTiO3 and (1 1 0) ...

This paper presents a comparison between several methods dedicated to the interpretation of V K-edge X-ray absorption near-edge structure (XANES) features. V K-edge XANES spectra of several V-bearing standard compounds were measured in an effort to evaluate advantages and limits of each method. The standard compounds include natural minerals and synthetic ...

The speciation of elements without pre-edge features preformed with X-ray absorption near edge structure (XANES) can lead to problems when the energy difference between two species is small. The speciation of arsenic (As) in plant samples was investigated using the mixtures As2S3/As2O5, As2S3/As2O3, or As2O3/As2O5. The data showed that ...

A series of complexes [Fe^IV(O)(TMC)(X)]⁺ (where X = OH^?, CF₃CO₂^?, N₃^?, NCS^?, NCO^?, and CN^?) were obtained by treatment of the well characterized ...

Application of in situ X-ray absorption near-edge spectroscopy (XANES) at the Al K-edge provides unique insight into the flexibilty of the aluminum coordinations in zeolites as a function of treatment or during true reaction conditions. A unique, previously not observed, pre-edge feature is detected in zeolites H-Mordenite and steamed and unsteamed H-Beta ...

Molybdate and tungstate are strong inhibitors of the purple acid phosphatases. The binding modes of these anions to the FeZn derivative of uteroferrin, the purple acid phosphatase from porcine uterus (FeZnUf), have been characterized by X-ray absorption spectroscopy at both the iron and zinc K-edges. Pre-edge data show that both FeZnUf.MoO4 and FeZnUf.WO4 ...

Anisotropic Fe K-edge and As K-edge x-ray absorption near-edge spectrum measurements on superconducting (Tc=52 K) (Sm0.95La0.05)FeAs(O0.85F0.15) field-aligned microcrystalline powder are presented. The angular dependence of Fe pre-edge peak (dipole transition of Fe 1s electrons to Fe 3d/As 4p hybrid bands) relative to the tetragonal ab plane of aligned ...

The knowledge of the oxidation state of the transition metal cations in Sr(2)FeMO(6) (M = W, Mo, Re and Sb) double perovskites is of paramount importance to understand their appealing magnetoresistive or magnetic properties. We present a systematic investigation of the valences of Fe, W, Mo, Re and Sb cations in these perovskites using three different and complementary techniques of analysis. We ...

The geometric structure of the catalytically relevant ferrous active site of phenylalanine hydroxylase (PAH) has been investigated using magnetic circular dichroism (MCD) and X-ray absorption (XAS) spectroscopies. From the excited state ligand field transitions in the MCD spectrum, the temperature and field dependence of these transitions, and the XAS ...

In YMn2O5 , the Mn atoms occupy two nonequivalent Wyckoff sites within the unit cell exhibiting different oxygen coordinations, i.e., the system can be characterized as a mixed-valence compound. For the formation of the orthorhombic crystal structure, Jahn-Teller distortions are assumed to play an important role. In this study, we aimed at the investigation of the crystal ...

Accurate X-ray absorption spectra (XAS) of first row atoms, e.g., O, are notoriously difficult to obtain due to the extreme sensitivity of the measurement to surface contamination, self-absorption, and saturation affects. Herein, we describe a comprehensive approach for determining reliable O K-edge XAS data for ReO(4)(1-) and provide methodology for ...

Optical microscopy, confocal Raman micro-spectrometry, X-ray photoelectron micro-spectroscopy (XPS) and synchrotron based micro-X-ray fluorescence (XRF), micro-X-ray absorption near edge spectroscopy (XANES) and micro-extended X-ray absorption fine structure (EXAFS) were used to investigate the reduction of aqueous Cr(VI) by pyrite. ...

We have measured resonant and off-resonant Auger-electron spectra of liquid water. Continuumlike transitions near and above the O1s vertical ionization energy are identified by the characteristic normal Auger-electron spectra. On the contrary, well-resolved spectator shifts of the main Auger-electron peak are observed at the liquid-water O1s absorption main edge and near the ...

We present a study on the temperature dependence of the electronic structure and magnetic properties of CexEu1-xCoO3 by means of x-ray absorption spectroscopy (XAS) and magnetic susceptibility measurements. Contrary to what was previously reported in literature for this compound, we identified the partially substituted Ce species to be tetravalent within ...

The coordination environment of Ti(IV) in seven natural and synthetic glasses of basaltic, trachytic, rhyolitic composition as well as four tektites has been studied using high-resolution Ti K-edge x-ray absorption near edge structure (XANES) spectroscopy at ambient temperature and pressure. Pre-edge features of Ti K-edge XANES spectra ...

Reactions between fluids and melts, which are not in redox-equilibrium, may potentially change the oxidation state of species in both phases. Diffusion of hydrogen and water in the melt is expected to be a controlling parameter for the adjustment of the redox state of multivalent elements in the melt, at least over short distances. In the present paper we have investigated experimentally the ...

We report resonant inelastic x-ray scattering (RIXS) study of d-d orbital excitations in Sr2CuO2Cl2 utilizing the intermediate state associated with a quadrupole transition. Fourfold azimuthal angle dependence of the pre-edge peak near the CuK absorption edge confirms that the in-plane pre-edge peak arises from the 1s?3dx2?y2 electric quadrupole ...

Much or all of the organic matter initially present on the Earth must have been destroyed by the high temperature reached during planetary differentiation. Anders [1] suggested that subsequent to differentiation the continuous, planet-wide accretion of interplanetary dust particles (IDPs) contributed a layer rich in organic matter to the surface of the early Earth, and that this pre-biotic organic ...

The ionization and fragmentation of carbon tetrafluoride excited at the C and F 1s thresholds are studied using soft x-ray excitation, threshold electron spectroscopy and state-selective coincidence techniques. The threshold electron spectra reveal indirect low-energy production from pre-edge resonances, and the structure at the thresholds is attributable ...

The coordination structure about Ni{sup 2+} in water at temperatures up to 525 C was measured by the X-ray absorption fine structure (XAFS) technique. Solutions containing 0.2 m NiBr{sub 2} and 0.2 m NiBr{sub 2}/0.8 m NaBr were explored at pressures up to 720 bar. For certain systems, both Ni and Br XAFS data were acquired and a global ...

The Fe K-edge X-ray absorption near-edge (XANES) spectra from Fe(1-x)Ga(x)SbO(4), having a rutile-like structure, have been investigated. Similar to the Ti K-edge XANES spectrum from TiO(2) (rutile), the low-energy pre-edge region observed in the Fe K-edge spectra is too broad to be representative of only a local, quadrupolar 1s ? 3d ...

Superconductivity is observed in the (Tl{sub 0.5}Pb{sub 0.5})(Ca{sub 1{minus}{ital x}}Y{sub {ital x}})Sr{sub 2}Cu{sub 2}O{sub 7{minus}{delta}} system in the composition range 0{le}{ital x}{lt}0.6, with a maximum {ital T}{sub {ital c}} of 108 K at {ital x}{similar to}0.2. For {ital x}{ge}0.6, the material becomes semiconducting. We have investigated the electronic structure of ...

Synchrotron-based X-ray absorption fine structure (XAFS) spectroscopy was used to investigate the reduction of aqueous Cr(VI) to Cr(III) in magnetite-bearing soils from Cr-contaminated sites. Soils from two field sites were examined, showing that mixed-valence Cr(III/VI) effluent is reduced to Cr(III) when associated with the magnetite fraction of the ...

Second-coordination sphere effects such as hydrogen bonding and steric constraints that provide for specific geometric configurations play a critical role in tuning the electronic structure of metalloenzyme active sites and thus have a significant effect on their catalytic efficiency. Crystallographic characterization of vertebrate and plant sulfite oxidase (SO) suggests that ...

We demonstrate that the oxidation state of iron (Fe3+/?Fe) can be determined with a precision of �0.02 (10% relative) on natural basalt glasses at mantle-relevant fO2 using Fe K-edge X-ray absorption near edge structure (XANES) spectroscopy. This is equivalent to �0.25 log unit resolution relative to the QFM buffer. Precise determination of the ...

Mn3d valence states and elementary electronic excitations in single-crystalline TbMnO3 were probed with resonant inelastic x-ray scattering (RIXS) (or resonant x-ray emission spectroscopy, RXES), polarized x-ray absorption spectra and ab initio electron-structure calculations. Polarized MnK -edge x-ray absorption spectra of TbMnO3 ...

We use hard x-ray resonant inelastic x-ray scattering (RIXS) and density functional theory (DFT) calculations to characterize charge transfer excitations in K(3)Mn(CN)(6). The combination of RIXS measurements and DFT calculations allows us to characterize the strength of the ligand-metal electronic interaction and assign the Raman resonances in the RIXS spectra to charge transfer excitations. With ...

We use hard x-ray resonant inelastic x-ray scattering (RIXS) and density functional theory (DFT) calculations to characterize charge transfer excitations in K3Mn(CN)6. The combination of RIXS measurements and DFT calculations allows us to characterize the strength of the ligand-metal electronic interaction and assign the Raman resonances in the RIXS spectra to charge transfer excitations. With ...

The passive film on sputter deposited thin film Fe-26Cr electrodes has been examined using the technique of in situ X-ray absorption near edge spectroscopy (XANES). During the X-ray spectroscopic measurements, the sample was maintained under electrochemical control in the pH 8.4 borate buffer electrolyte. The appearance of the distinctive Cr(VI) XANES ...

The passive film on sputter deposited thin film Fe-26Cr electrodes has been examined using the technique of in situ X-ray absorption near edge spectroscopy (XANES). During the X-ray spectroscopic measurements, the sample was maintained under electrochemical control in the pH 8.4 borate buffer electrolyte. The appearance of the distinctive Cr(VI) XANES ...

Cu:SAPO-5 and Cu:SAPO-11 were prepared by conventional and hydrothermal ion exchange. Copper incorporation is increased six-fold by hydrothermal ion exchange relative to conventional methods. In all cases, the amount of copper taken up by SAPO-11 is superior to uptake in SAPO-5. Copper is divalent and in tetragonally-distorted octahedral environments in the as-prepared samples independent of the ...

Methyl-coenzyme M reductase (MCR) catalyzes the terminal step in the formation of biological methane from methyl-coenzyme M (Me-SCoM) and coenzyme B (CoBSH). The active site in MCR contains a Ni-F(430) cofactor, which can exist in different oxidation states. The catalytic mechanism of methane formation has remained elusive despite intense spectroscopic and theoretical investigations. On the basis ...

Methyl-coenzyme M reductase (MCR) catalyzes the terminal step in the formation of biological methane from methyl-coenzyme M (Me-SCoM) and coenzyme B (CoBSH). The active site in MCR contains a Ni?F₄₃₀ cofactor, which can exist in different oxidation states. The catalytic mechanism of methane formation has remained elusive despite intense spectroscopic and theoretical ...

Oxygen-evolving complex (Mn4Ca cluster) of Photosystem II cycles through five intermediate states (Si-states, i =0-4) before a molecule of dioxygen is released. During the S-state transitions, electrons are extracted from the OEC, either from Mn or alternatively from a Mn ligand. The oxidation state of Mn is widely accepted as Mn4(III2,IV2) and Mn4(III,IV3) for S1 and S2 states, while it is still ...

Oxidative stress has been suggested to contribute to neuronal apoptosis associated with Alzheimer's disease (AD). Copper may participate in oxidative stress through redox-cycling between its +2 and +1 oxidation states to generate reactive oxygen species (ROS). In vitro, copper binds to the amyloid-? peptide of AD and in vivo, copper is associated with amyloid plaques characteristic of AD. As a ...

... Title : ABSORPTION LINE SERIES AND AUTOIONIZATION RESONANCE STRUCTURE ANALYSIS IN THE ULTRAVIOLET SPECTRUM OF SR I,. ...

... The optical absorption of several air-bridge structures was modeled, and optimized dimensions and electrode conductivity are presented which ...

... ADD116257. Title : ENERGY ABSORPTION BY STRUCTURAL COLLAPSE IN DUAL PHASE STEEL TUBES,. Corporate Author : ...

Oxidative stress has been suggested to contribute to neuronal apoptosis associated with Alzheimer's disease (AD). Copper may participate in oxidative stress through redox-cycling between its +2 and +1 oxidation states to generate reactive oxygen species (ROS). In vitro, copper binds to the amyloid-beta peptide of AD, and in vivo, copper is associated with amyloid plaques characteristic of AD. As a ...

... Title : Space-Time Structure of Auroral Radio Absorption Events Observed ... evolution shows rapid intensifications of the moving absorption patches. ...

Fe K-edge XANES spectra have been measured in more than 35 Fe(II) and Fe(III)-bearing minerals. The separation between the average pre-edge centroid positions for Fe(II) and Fe(III) is 1.4 +/- 0.1 eV. Examination of calculated pre-edge features of mechanical mixtures of phases containing different proportions of Fe(II) and Fe(III) reveals that different ...

An area of contention in ELNES simulations using density functional theory (DFT) has been whether geometry optimisation is entirely necessary to obtain useful results. This issue is addressed for bulk magnesium oxide by comparison of results with and without energy minimisation of structures. An MgO (001) surface was investigated. Experiments were carried out to determine how ...

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 ...

Iron K-edge X-ray absorption pre-edge features have been calculated using a time-dependent density functional approach. The influence of functional, solvation, and relativistic effects on the calculated energies and intensities has been examined by correlation of the calculated parameters to experimental data on a series of 10 iron model complexes, which ...

X-ray absorption around oxygen K-edge of Tl{sub 2}Ba{sub 2}Ca{sub 2}Cu{sub 3}O{sub 10} high-{ital T}{sub {ital C}} superconductors was measured by means of a bulk sensitive x-ray fluorescence yield detection method. Three distinct pre-edge peaks are revealed. They are ascribed to core-level excitations of oxygen 1s electrons to empty states at Fermi level ...

Two structurally homologous Mn compounds in different oxidation states were studied to investigate the relative influence of oxidation state and ligand environment on Mn K-edge X-ray absorption near-edge structure (XANES) and Mn Kbeta X-ray emission spectroscopy (Kbeta XES). The two manganese compounds are the di-mu-oxo compound ...

From the reaction mixture of 3,6-dichlorobenzene-1,2-dithiol, H(2)(Cl(2)-bdt), [CrCl(3)(thf)(3)], and NEt(3) in tetrahydrofuran (thf) in the presence of air, dark green crystals of [N(n-Bu)(4)](2)[Cr(Cl(2)-bdt)(3)] (S = 1) (1) were isolated upon addition of [N(n-Bu)(4)]Br. Oxidation of the AsPh(4)(+) salt of 1 with [Fc]PF(6) yielded microcrystals of [AsPh(4)][Cr(Cl(2)-bdt)(3)] (S = (1)/(2)) (2) ...

Two structurally homologous Mn compounds in different oxidation states were studied to investigate the relative influence of oxidation state and ligand environment on Mn K-edge X-ray absorption near-edge structure (XANES) and Mn KBeta X-ray emission spectroscopy (KBeta XES). The two manganese compounds are the di-(mu)-oxo compound ...

... Title : EXTENDED X-RAY ABSORPTION FINE STRUCTURE: A MODERN STRUCTURAL TOOL IN MATERIALS SCIENCE. Corporate Author : ...

... Title : THE ROLE OF MOLECULAR WEIGHT AND STRUCTURE IN THE ABSORPTION OF ULTRASOUND BY PROTEINS. Corporate Author : ...

... COMPLEX COMPOUNDS, SPECTROSCOPY, STRUCTURAL PROPERTIES, ABSORPTION, PYRIDINES, PYRAZOLES, INDOLES, BRIDGES ...

... Title : ON THE THEORY OF THE FINE STRUCTURE OF THE X RAY ABSORPTION SPECTRA OF IONS IN SOLUTIONS. ...

... Title : INVESTIGATION OF STRUCTURE OF FERROCENE AND FERRICYANIUM BY MEANS OF X-RAY K-ABSORPTION SPECTRA,. ...

... STRUCTURAL GEOMETRIES: THE EFFECTS OF EDGE ... of strength, energy absorption and transition ... difference in transition temperature for the ...

... ABSORPTION SPECTRA, BAND SPECTRA, STRESSES, MOLECULAR STRUCTURE, POTASSIUM COMPOUNDS, LITHIUM COMPOUNDS ...

... Accession Number : ADA302640. Title : Scattering Absorption, and Generation of Microwaves in Time Varying and Structured Plasmas. ...

... Accession Number : AD0261240. Title : OPTICAL TRANSITIONS NEAR THE ABSORPTION EDGE IN CDS. I. - BAND STRUCTURE IN CDS. ...

... Title : INVESTIGATION OF THE ABSORPTION SPECTRA OF InSb-InAs SOLID SOLUTIONS WITH A VIEW TO BAND STRUCTURE,. ...

RF energy absorption by plasma column surrounded by periodic coupling structure, noting similarities

... ulcrl=. 22 074 Page 2. ENERGY-ABSORPTION CAPABILITY OF ... absorption capability of composite subfloor bean structures. Before it is possible ...

Mn K-edge X-ray absorption near-edge spectra (XANES) and magnetic studies for ferroelectromagnetic compounds RMnO3 (R=Sc,Y) are reported. ScMnO3 shows stronger d-p hybridization with a triangular antiferromagnetic (AF) order of TN=133K and a spin reorientation Tsr=23K, as compared to TN=74K for YMnO3. The identical main threshold edge energy of 6545eV indicates Mn3+ character. ...

We report measurements of the Na1s contribution to the nonresonant inelastic x-ray scattering (NRIXS) from NaCl and NaF. Prior x-ray absorption studies have observed two pre-edge excitons in both materials. The momentum-transfer dependence ( q dependence) of the measured NRIXS cross section and of real-space full multiple scattering and Bethe-Salpeter ...

Electron-density analysis has been developed to make use of the intensity difference in the resonant X-ray magnetic scattering (RXMS) between left- and right-circular polarizations. The magnetic electron density was obtained at the electronic transition energy, E = 7.1082 keV in the Fe K pre-edge by using the difference-Fourier synthesis. Difference peaks due to magnetic ...

The fluctuations of absorption coefficient which appear on the high energy side of x-ray absorption edges have been separated historically and physically into two different but similar effects. The structure in and near the edge (Kossel structure) has bee...

The mononuclear non-heme iron active site of N694C soybean lipoxygenase (sLO1) has been investigated in the resting ferrous form using a combination of Fe K-pre-edge, near-edge (using MXAN full multiple-scattering approach) and EXAFS methods. The results indicate that the active site is six coordinate (6C) with a large perturbation in the first shell bond distances in ...

In this dissertation, investigations on the local lattice structures for a variety of novel materials using Extended X-ray Absorption Fine Structure (EXAFS) technique are presented. Different experiment schemes were applied to obtain EXAFS data with high quality, and some interesting results were obtained by careful analysis. The power ...

... Accession Number : ADA281305. Title : X-Ray Absorption Spectra and Structure of Some Nickel Oxides (Hydroxides). Descriptive ...

... Abstract : First application of extended x-ray absorption fine structure (EXAFS) technique to measurements of interatomic distance, local order, and ...

The usefulness of x-ray absorption spectroscopy in studies of electronic structure in materials is discussed. 7 refs., 4 figs. (CBS)

... Title : STRUCTURE OF K X-RAY ABSORPTION EDGES OF ARGON AND KRYPTON IN GASEOUS AND SOLID STATES. ...

An analysis of resonance absorption of neutrons in materials having grain structures is extended to the case in which the grains occupy a sizeable fraction of the absorber volume. (T.F.H.)

X-ray spectroscopy codes were applied to achieve quantitative interpretation of x-ray absorption near edge structure

... Accession Number : ADD126620. Title : Hydrogen Absorption and Electronic Structure of Magnesium-Based Yttrium and Scandium Dilute Alloys,. ...

... of EXAFS (Extended xray absorption fine structure ... have recorded the extended x-ray-absorption fine structure ... above the carbon K edge for diamond ...

X-ray absorption spectroscopy is now being applied to the study of a wide range of surface structures. The usefulness of surface EXAFS (SEXAFS) is illustrated by reviewing measurements on the oxidation of aluminum, the absorption of Te and I on silicon an...

We describe the use of Cl K-edge X-ray Absorption Spectroscopy (XAS) and both ground state and time-dependent hybrid density functional theory (DFT) to probe electronic structure and determine the degree of orbital mixing in M-Cl bonds for (C5Me5)2MCl2 (M = Ti, 1; Zr, 2; Hf, 3; Th, 4; and U, 5), where we can directly compare a class of ...

Using a configuration-interaction impurity-Anderson model we calculate core-hole X-ray Photoemission Spectra (c-XPS) for some early Transition Metal (TM) insulating compounds. Because in these compounds the valence (ligand) band is completely filled, the TM on-site Coulomb repulsion U_dd is treated exactly, as well as the 3d-core hole interaction U_dc. The ground state of such a ligand-TM system ...

We present a valence-state model to explain the characteristics of a recently observed pre-edge feature in Mn L{sub 3} x-ray magnetic circular dichroism (XMCD) of ferromagnetic (Ga,Mn)As and (Al,Ga,Mn)As thin films. The prepeak XMCD shows a uniaxial anisotropy, contrary to the cubic symmetry of the main structures induced by the crystalline electric field. ...

The local environments around Ti, Cr, and several light rare-earth elements (La, Ce, and Nd) were investigated by in-situ XANES spectroscopy in a number of complex borosilicate glasses and melts (to 1120 �C) that are used for nuclear waste storage. Examination of the high-resolution XANES spectra at the Ti K-edge shows that the average coordination of Ti changes from ~5 to ~4.5. Cr is dominantly ...

The link between brown colour and vacancy structures in natural diamond and has been studied through the techniques of aberration corrected scanning transmission electron microscopy (AC-STEM) and electron energy loss spectroscopy (EELS). Bright field (BF) and high angle annular dark field (HAADF) STEM imaging modes have revealed discrete patches of stronger contrast, of the ...

... RESONANCE, *CATALYSTS), (*PARAMAGNETIC RESONANCE, CATALYSTS), NUCLEAR STRUCTURE, CATALYSIS, ABSORPTION SPECTRA ...

... STRUCTURE, SPECTROSCOPY, INFRARED SPECTROSCOPY, ABSORPTION SPECTRA, ULTRAVIOLET SPECTROSCOPY, CHEMICAL ...