bluuebunny/crossref_metadata_2025 huggingface dataset:
Study of Ultrasonic Behavior of Salol near Melting Point Using Interior Transducer-Type Cell
Authors: Kamioka Hiroaki
Published: March 2014

An interior transducer-type cell was designed for measuring the ultrasonic velocity and attenuation of a sample under both conditions of melting and solidifying processes with observing the condition of the sample from outside the cell. Using the cell, the sound velocity and attenuation of Salol were measured in the range between the room temperature and 80°C, including the melting temperature. The results for the ultrasonic behavior in the vicinity of the melting point are reported and siscussed.
Computer Simulation of Phonon Conduction in Langmuir-Blodgett Films
Authors: Ozawa Satoru , Hiki Yosio
Published: March 2014

Molecular dynamics computer simulation has been carried out to study the diffusive phonon transport produced by a pulse input power in one-dimensional layer-stacked mass-spring model crystals. Diffusion-like behaviors were really observed when anharmonic forces were taken into account for the springs. The time variations of the phonon kinetic energy at various positioins in the crystal were analyzed in order to determine the thermal diffusivity of the crystal. The results were compared with our previous experimental thermal diffusivity data for LB films of arachidic acid, and the agreement between the two kinds of results was found to be very satisfactory.
Application of Scanning Single-Pulse Ultrasonic Spectroscopy to Structural Evaluation of CFRP
Authors: Okabe Hirotaka , Taki Seiji , Matsushige Kazumi
Published: March 2014

Scanning single-pulse ultrasonic spectroscopy system using a wide-band polymer transducer, an X-Y stage, and a frequency analysis with fast Fourier transformation (FFT) was successfully applied for the evaluation of the internal structure in carbon fiber reinforced plastics (CFRP). The analyzed power spectral data revealed clearly the details of the internal structure of the sample such as the diameter of carbon fibers, the location of the separation within the CFRP layers. This method is suggested to become a powerful method for the nondestructive inspection of composite materials including the CFRP.
Application of the Bayesian Estimation Method to the EXAFS Data Analysis
Authors: Zschech Ehrenfried , Blau Winfried
Published: March 2014

The Bayesian estimation method which is based on mathematical statistics combines experimental signals and pre-information in a common loss function. We have improved the original version of the Bayesian method and can take into account implicit constraints between the parameters of the EXAFS function, that must be fulfilled only within chosen error bounds. These linear relations connect occupation probabilities or phase fractions, coordination numbers, interatomic distances and mean-square relative displacements of the atoms.
Near Edge Electron Energy Loss Spectroscopy: Comparison to X-ray Absorption
Authors: Hitchcock Adam P.
Published: March 2014

Inelastic electron scattering provides a convenient, lab-based alternative to bremsstrahlung or synchrotron radiation X-ray spectroscopy for inner-shell excitation studies of gases, solids and surfaces. The current capabilities of inner-shell electron energy loss spectroscopies (ISEELS) are reviewed and compared to X-ray techniques. Issues discussed include: momentum transfer dependence, oscillator strength determination, spatial and energy resolution, orientational sensitivity. Examples are given of the application of EELS to gases, solids and surfaces.
New Approach to the Theory of Atomic Optical Potential in Solids
Authors: Fujikawa Takashi , Saito Akira , Hedin Lars
Published: March 2014

We develop an approximation for the optical potential in a solid valid at intermediate energies, say energies from some 50 eV and larger. The importance of good optical potentials at these energies is clear from experimental and theoretical work on elastic electron-atom scattering. We cannot however directly take over free-atom potentials for use in a solid. For one thing the valence electrons are largely reorganized when the atom is placed in a solid. One also has to consider the screening effects in solids. Our approximation for the optical potential builds on the G
W-expression. We separate the RPA polarization propagator in a core electron and a valence electron part, and can then achieve a corresponding separation of the optical potential.
The Structure of Photoexcited Platinum Pop Measured with Microsecond Resolved XAFS
Authors: Līviņŝ Pěteris , Thiel Daniel , Stern Edward , Lewis Aaron
Published: March 2014

We report a µsec resolved XAFS measurement of the excited triplet electronic state 3A2u
(dσ*
pσ) of Pt2(P2O5H2)4
4- in solution employing a new technique. The measurement utilizes a vertical flow of 10 m/s produced by a small nozzle, similiar to that of a dye laser. A line focused laser excites the molecules in the flow while a 10 µm vertically confined line of x-ray radiation probes the flow downstream of the laser. We find that the phosphor planes of the molecule in the excited state each move inward along the Pt-Pt axis by 0.26(08) Å, relative to its the center. Also, the platinum phosphorous bonds contract 0.050(11) Å. The optical transition promotes an electron from an anti-bonding orbital to a bonding orbital, and the observations indicate that this occupied bonding orbital strongly increases the overall structural bonding forces of the molecule.
Structural Study of the Si/B(√3×√3)R30° GexSi1-x(111) Interface by Spatially Selective Diffraction Anomalous Fine Structure (DAFS)
Authors: Tweet D. J. , Akimoto K. , Hirosawa I. , Tatsumi T. , Kimura H. , Mizuki J. , Sorensen L. B. , Bouldin C. E. , Matsushita T.
Published: March 2014

We have applied a new x-ray structural technique, Diffraction Anomalous Fine Structure (DAFS), to a buried reconstructed interface, Si/B(√3×√3)R30°/Ge
x
Si1-x
(111) (abbreviated Si/B√3/Ge
x
Si1-x
(111)). While Ge Kedge XAFS alone gives information about the average local structure surrounding all of the Ge in the sample, by combining the complementary abilities of XAFS and x-ray diffraction, DAFS is able to examine the local structure surrounding just the Ge at the interface, thus exhibiting spatial selectivity. We have made simultaneous XAFS and DAFS measurements of this interface and observed clear differences in the derived χ(k) and resulting Fourier transforms.
Site-Specific X-ray Absorption Spectroscopy Using DIFFRAXAFS
Authors: Pickering Ingrid J. , Sansone Michael , Marsch James , George Graham N.
Published: March 2014

The technique of Diffraction-XAFS , or DIFFRAXAFS probes the energy-dependent intensity variations of a diffraction peak at energies close to an absorption edge of one of the atoms in the phase, yielding electronic and local atomic information which is analogous to that obtained in an XAFS experiment. In this paper we demonstrate the ability of powder DIFFRAXAFS to give site-specific information in the XANES region of Co3O4. We also outline a method for removing the bulk absorbance effects from the diffraction data using a simultaneous measurement of transmittance, and demonstrate the method for a control peak of lithium carbonate.
Photoconductivity Measurements of X-ray Absorption Fine Structures in Liquids in the Soft X-ray Region: Si and Cl K-edge
Authors: Sham T. K. , Holroyd R. A. , Xiong J.-Z. , Feng X. H. , Yang B. X.
Published: March 2014

Photoconductivity measurements of X-ray absorption fine structures (XAFS) at the Si and Cl K-edge have been carried out in a liquid cell for (CH3)4Si, [(CH3)3Si]4Si and CCl4, either as a pure liquid or in a 2,2,4-trimethylpentane solution. It is found that for the pure liquids and their concentrated hydrocarbon solutions, all K-edge XAFS spectra are inverted as expected under the condition of total absorption. A sharp conductivity dip is also observed in CCl4 at the Cl K-edge. The concentration dependence of the XAFS spectrum of CCl4 is reported in some details. These results are discussed in terms of the soft X-ray induced ion yields of the solute and solvent molecules in liquids.
Theory for Yield Spectra Produced by Core-Electron Excitation
Authors: Emura S. , Nomura M. , Bauchspieß K. R. , Murata T. , Harada K. , Maeda H.
Published: March 2014

A theory is developed on yield spectra of an optical luminescence produced by core-electron excitation. In this model, the yield in each excitation-luminescence cycle are assigned to be different. All anomalous spectra observed in experiments such as those with a negative jump, and a positive jump with an inverted oscillatory part are well reproduced, and furthermore, new yield spectra (destroyed type) are predicted.
Oxygen and Nitrogen Fluorescence EXAFS Measurements by Gas Scintillation Proportional Counters
Authors: Maeyama Satoshi , Sugiyama Munehiro , Oshima Masaharu , Shimizu Kazuaki , Shoji Takashi
Published: March 2014

An ultrahigh vacuum compatible and compact x-ray fluorescence detector of gas scintillation proportional counter type have been developed for measuring fluorescence yield EXAFS of ultralow-Z elements. Fluorescence yield EXAFS spectra were obtained above the N and 0 K-edges of Si3N4 and Sio2 films for the first time by using this newly developed detector.
EXAFS Experiments with High-Power Rotating Anode X-rays
Authors: Sakurai Kenji
Published: March 2014

A new laboratory EXAFS facility, which is composed of a dedicated high-power rotating anode X-ray generator and a Johanson-type focusing spectrometer, has been developed. The present X-ray source has provided a line focal spot of about 0.1 mm in width, with a maximum allowable current of 900 mA when operated at a tube voltage of 20 kV. High intensity monochromatic X-rays of more than 106 cps, which are free from higher order harmonics, have been obtained with sufficient energy resolution. The performance of the present EXAFS facility, as well as its application to practical samples, are demonstrated.
A Laboratory EXAFS Spectrometer for High Temperature Molten Materials
Authors: Omote Kazuhiko , Tohji Kazuyuki , Waseda Yoshio , Kiku Atsunori , Funahashi Manabu
Published: March 2014

A Laboratory EXAFS spectrometer for both as a single or double-crystal mode with a high-temperature furnace has been developed for obtaining the short-range ordering structure of molten materials. The surface of molten materials is always held in the horizontal position by means of a vertical-type goniometer with a movable x-ray generator, so that the free surface of melts can be measured at temperatures higher than 1300°C in air. The usefulness of this apparatus has been confirmed by obtaining an EXAFS spectrum of liquid Bi4Ge3O12.
Double Flat Crystal Spectrometer in Dispersive Arrangement for Laboratory XAFS Spectroscopy
Authors: Uehara Yasushi , Kataoka Masayuki , Ogama Tetsuo , Kawabata Atsushi , Nishihagi Kazuo , Taniguchi Kazuo
Published: March 2014

A new XAFS spectrometer with a double flat crystal monocromator has been developed. The energy resolution of the spectrometer is estimated to be below 10eV at 20keV from the FWHM of Mo Kα1 line (17.479keV). Experiments under various temperature and vacuum conditions are possible with a movable rotating anode and a high vacuum type sample chamber.
Angle Dependence of X-ray Magnetic Circular Dichroism at Fe K-edge in Rare-Earth-Iron-Garnet
Authors: Yamazaki Hitoshi , Maruyama Hiroshi , Kobayashi Kenji , Shimomi Kimito
Published: March 2014

X-ray magnetic circular dichroism has been measured at the Fe K-edge in ferrimagnetic Ho-iron-garnet. By measuring the dependence of dichroic spectrum on the angle between magnetization direction and the X-ray wave vector, dipolar and quadrupolar contributions are extracted on the basis of the recently developed theory. The pre-peak structure is mainly assigned to the 1s-3d transitions dipole-allowed by the charge transfer from O 2p to 3d-states of Fe3+ ion in tetrahedral site.
Evidence of Multielectron Excitations in Magnetic Circular X-ray Dichroism of Rare Earth Compounds
Authors: Dartyge E. , Baudelet F. , Fontaine A. , Giorgetti Ch. , Pizzini S. , Kappler J.-P. , Krill G. , Brouder Ch.
Published: March 2014

This letter reports the first experimental evidence of multielectron excitations in magnetic circular x-ray dichroism (MCXD) spectra, measured at the LI,II,III-edges of Rare Earths (RE) in several RE-Transition Metal (Fe, Co) compounds. These multielectron features involve transitions from the 2p and 4d levels and exhibit a very strong magnetic enhancement compared to normal MCXD.
Magnetic Moment and Intensity of Magnetic X-ray Dichroism at the K-edge in Fe73.6Ni26.4 Alloy
Authors: Sakurai H. , Itoh F. , Maruyama H. , Koizumi A. , Kobayashi K. , Yamazaki H. , Kawata H.
Published: March 2014

The temperature dependence of circularly magnetic x-ray dichroism (CMXD) spectra at the Fe K-edge has been measured in a Fe73.4Ni26.4 alloy. The CMXD signal intensities at the Fe K-edge are proportional to the total magnetization of the alloy.
Bonding on Surfaces: The SEXAFS Point of View
Authors: Arvanitis Dimitri , Lederer Thomas , Comelli Giovanni , Tischer Markus , Yokoyama Toshihiko , Tröger Larc , Baberschke Klaus
Published: March 2014

The temperature dependent Surface EXAFS of O and N on Ni(100) and O on Cu(100) is analyzed. The first moments of the Pair Distribution Function (PDF) are determined, including anharmonic contributions. From a systematic analysis of the pair potentials it is proposed that for the reconstructed surfaces the bond is more covalent, for the unreconstructed ones more ionic. The value of the charge transfer to the adatom is found to be ∼0.63 electrons for the ionic cases. Upon the reconstruction of the Cu(100) surface the static part of the disorder is found to increase. The dissociation process of O2 molecules on Cu(100) is studied. The differences in the PDF moments between the different adsorption states are shown to correlate to the strength of chemisorption.
Spin Transition Studied by XANES Spectroscopy: A Multiple Scattering Approach
Authors: Moulin Ch. Cartier dit , Sainctavit Ph. , Briois V.
Published: March 2014

Iron ion in Fe(II)(o-phenantroline)2(NCS)2 presents an abrupt and complete spin transition t2g
4eg
2[S=2] → t2g
6eg
0[S=0] around T=170K. We have recorded iron K-edge spectra above and below 170K and it is found that they are strongly modified during the transition. The strong XANES modifications for the two spin phases can find their origin in electronic configuration changes or in structural modifications. We apply Full Multiple Scattering theory to sort out the origin of the modifications.
EXAFS Studies of Interfaces in ZnTe/CdSe Superlattices
Authors: Kemner K. M. , Bunker B. A. , Luo H. , Samarth N. , Furdyna J. K. , Weidmann M. R. , Newman K. E.
Published: March 2014

Polarization-dependent grazing incidence EXAFS, employing the electron yield technique, has been used to study the local atomic structure of two different short-period ZnTe/CdSe (001) superlattices grown by MBE. This data indicate Zn-Se and Cd-Te coordination numbers greater than those expected for sharp interfaces in the superlattice. Although strain would appear to suppress interdiffusion, we show that the results are consistent with an interchange of Zn and Cd atoms across the Zn-Se interface, and Se and Te atoms across the Cd-Te interface. We discuss accommodation of this increased strain through bond bending and bond stretching. We also discuss other experiments in progress to more fully understand these interfaces.
An In-situ Investigation into Structural Ordering on Ag Surfaces during the Underpotential Deposition of Pb Monolayers Using X-ray Absorption Spectroscopy under Conditions of Total External Reflection
Authors: Balut A. , Robinson J. , Roberts K. J. , Herron M. E. , Walsh F. C.
Published: March 2014

The underpotential deposition of a Pb monolayer at -0.525V versus S.C.E. onto a Ag polycrystalline thin film in an electrolyte solution of 0.5M sodium acetate, 5 mM lead acetate and 0.01 M Acetic Acid at 20°C has been examined in-situ using reflectivity EXAFS together with a specially designed electrochemical cell. The data reveal the existence of an Ag-Pb bond length of 2.58Å.
The Influence of Metal-Support Interactions on the Whiteline Intensity
Authors: Vaarkamp Marius , Miller Jeff T. , Modica Frank S. , Koningsberger Dick C.
Published: March 2014

The whiteline intensity of Pt/K-LTL catalysts reduced at 300, 450, and 600°C decreases with increasing reduction temperature. This change in whiteline intensity was ascribed to the removal of hydrogen from the metal-support interface by reduction at higher temperature.
EXAFS Study of the Local Structure around Cobalt in Co–Mo/Al2O3 Catalysts
Authors: Yokoyama Yasuharu , Teranishi Kenji , Nishijima Akio , Matsubayashi Nobuyuki , Shimada Hiromichi , Nomura Masaharu
Published: March 2014

The structure around cobalt in a series of Co-Mo/Al2O3 catalysts was studied by means of the X-ray Absorption Fine Structure technique. Low Co loading yields the dominant phase of a Co-O-Mo (I) structure, in which six-coordinated Co atoms on the Al2O3 surface have appreciable interaction with Mo atoms. An increase of the Co loading leads to pronounced formation of a CoAl2O4-like structure which is mainly present at the subsurface of Al2O3. CoMoO4 microcrystallites (Co-O-Mo (II)) are found to be formed independent of the Co/Mo ratio in the catalysts with high Mo loadings. Both Co-O-Mo (I) and Co-O-Mo (II) are postulated as precursors which transfer to the active “Co-Mo-S” phase during sulfiding of the catalysts.
Valence Variation of Yb Encapsulated in the Supercage of Y-Type Zeolite
Authors: Tanaka Tsunehiro , Hanada Tomoko , Yoshida Satohiro , Baba Toshihide , Ono Yoshio
Published: March 2014

Yb/K-Y exhibits various catalytic reactivities by evacuation at various temperatures. By evacuation with elevating temperature, successive desorption of hydrogen, ammmonia, and hydrogen was observed. Yb L2, edge XANES spectra showed that Yb is present as a mixture of Yb2+ and Yb3+. The sample as prepared consists of Yb3+ species mainly. With elevating the evacuation temperature, the fraction of Yb2+ increases and reaches a maximum in the vicinity of 500 K. Then, the fraction of Yb2+ decreases and reaches a minimum at 873 K. The valence variation is in a good accordance with a catalytic variation. Desorption of hydrgen and ammonia corresponds to the chemical change of Yb species: amine → imine → nitride.
XAFS Studies of Copper/ Zeolite Catalysts for NOx Reduction
Authors: Nakayama Toshiro , Yasumatsu Tatsuro , Kokitsu Mikako , Tabata Takeshi , Sakane Hideto
Published: March 2014

XANES and EXAFS of Cu ion-exchanged zeolite catalysts effective for selective reduction of NOx by hydrocarbons have been studied by using a laboratory EXAFS spectrometer. The structural change of Cu species during catalytic reaction is suggested from the changes of Cu-Cu interaction peaks in EXAFS Fourier transforms and of the peaks due to multiple scattering in XANES spectra. Copper ions before reaction exist as isolated ions at the ion-exchanging sites, while Cu atoms in deactivated catalyst are sintered to form cluster species.
EXAFS Study of Metal-Coated Particles Produced by Ball Milling
Authors: Heald Steve M. , Jayanetti Sumedha , Pandya Kaumudi I.
Published: March 2014

EXAFS measurements have been carried out on mixtures of Sn with Ge and Si, and Pt with SiO2 which have been ball milled for extended periods. In these systems the brittle component (Ge, Si, or SiO2) is ground to nanocrystalline dimensions while the ductile metal is found to coat the outer surface of the particles. Analysis shows that in the Sn-Ge and Sn-Si systems, mixing at the interface is found to form apparently cubic SnGe and SnSi alloys respectively. In the Pt-SiO2 system while no mixing is observed, the Pt is found to be highly dispersed on the surface of SiO2 particles.
Spontaneous Dispersion and Coordination Structure of CuBr2 on Alumina Surface
Authors: Cai Cai , Xiaohai Xiaohai , Xie Xie , Youchang Youchang , Pan Pan , Gaofeng Gaofeng , Wang Wang , Zhijie Zhijie , Tang Tang , Yotiqi Yotiqi
Published: March 2014

The phenomenon about dispersing spontaneously of CuBr2on the surface of γ-Al2O3 only by grinding the mixture of CuBr2 and γ-Al2O3 has been observed with XRD, EXAFS study shows that reconstruction of chemical bonds occurs as CuBr2 is dispersed, Such process might be a special chemical interaction in heterogeneous catalysis system and the origin of dispersion of CuBr2 on the surface of γ-Al2O3. Cu2+ and Br-ions might cover the surface of γ-Al2O3 in the way of monolayer or submonolayer and their coordination is variable.
The Isolation of Dispersion Phase EXAFS and Coordination of Ni Ions on the Surface of NiO/γ-Al2O3 System
Authors: Cai Xiaohai , Lu Kunquan , Xie Youchang , Xu Xianping , Tang Youqi , Dong Jun
Published: March 2014

The coordination structure of dispersed phase in the NiO/γ-Al2O3 system has been isolated by applying the EXAFS principle of mixed phases. Both Ni-O and Ni-Ni coordination states vary with the Ni content in the sample, but once the dispersion amount of NiO reaches the maximum- -threshold, in the coordination curve an inflection point appears and the coordination of dispersed phase gets stable. The results show that the NiO dispersed phase has its own characteristic coordination structure. On the basis of the results, a monolayer dispersion model has been suggested.
Structural Characterization of the Binding Site in the MerR Metalloregulatory Protein
Authors: Clark Kimber , Utschig Lisa , O'Halloran Thomas V. , Penner-Hahn James E.
Published: March 2014

The Zinc and Cadmium forms of MerR, a metalloregulatory protein involved in bacterial mercury detoxification , have been studied using X-ray absorption spectroscopy. Previous work has shown the Hg-MerR to have a unique three coordinate HgS3 environment. Preliminary analysis of the EXAFS data for the Cd- and Zn-MerR derivatives suggests a higher coordination number in these cases.
XAFS Studies of Some Transition Elements Highly Accumulated in Seashells
Authors: Numako Chiya , Nakai Izumi , Okoshi Kenji , Ishii Toshiaki
Published: March 2014

XAFS analysis was used to reveal local atomic environment of manganese in the intracellular and extracellular granules from kidney tissues in several kinds of marine bivalves. The Mn K-absorption spectra of the kidney granules were measured in a fluorescence mode. The overall spectral shapes and the positions of the Mn K-absorption edge of the kidney granules of the bivalves are similar to each other and somewhat resemble those of eosphorite (MnAl(PO4)OH)2·H2O) which contains Mn(II). These results, combined with those of IR analysis, suggest that manganese in the kidney granules exist as a phosphate with 6-fold coordination of oxygen atoms.
Structural Characterisation of Azurin from Pseudomonas aeruginosa and some of Its Methionine-121 Mutants
Authors: Murphy Loretta M. , Strange Richard. W. , Karlsson B. Göran , Lundberg Lennart G. , Pascher Torbjörn , Reinhammar Bengt , Hasnain S. Samar
Published: March 2014

Azurin from Pseudomonas aeruginosa and two mutants where the methionine ligand has been mutated have been studied in order to directly investigate the functional and structural significance of this ligand in the blue copper proteins. Redox potentials, x-ray absorption fine structure (XAFS), electron paramagnetic resonance (EPR) and optical spectra are obtained in an attempt to provide a direct correlation between the spectrochemical properties and the immediate structure of this redox centre.
Multielectron Excitations of Ni and Zn in X-ray Absorption
Authors: Ito Yoshiaki , Nakamatsu Hirohide , Mukoyama Takeshi , Omote Kazuhiko , Yoshikado Shinzo , Takahashi Masao , Emura Shuichi
Published: March 2014

The x-ray absorption measurements of Ni and Zn are carried out at various temperature in the energy region where multiple transitions are expected. XAFS oscillations mask the K+L transition edges of these elements and extend up to over 20 A-1. In the synchrotron radiation facility, the sensitivity of about 5×10-4 in the detection is experimentally achieved in the energy region of multiexcitations. However, no features attributed to multiple photoexcitation are detected in the spectra. The result can be explained by theoretical predictions due to lower shakeup probabilities for K+L transitions in Ni and Zn.
Anisotropy of the Core Hole Relaxation in X.A.S. as Probed in Square Planar Cuprates
Authors: Tolentino H. , Medarde M. , Jfontaine A. , Baudelet F. , Dartyge E.
Published: March 2014

The multichannel approach of XPS and XAS is now well-documented. The polarisation-dependent Cu K-edge spectra of the square planar cuprates, account for an anisotropic weighting of the two well -screened and poorly-screened channels.
Local Structure and Superconductivity of CaLaBaCu3Oy
Authors: Kuwahara Y. , Oyanagi H. , Yamaguchi H. , Nishihara Y. , Okajima Y. , Yamaya K. , Aono M.
Published: March 2014

The local structure and electronic state of CaLaBaCu3Oy (CLBCO) as a function of the oxygen composition (6.66<y<6.90) are investigated by XAFS on the Cu K-edge using synchrotron radiation. The XAFS spectra show that the in-plane local structure of CaLaBaCu3Oy is tetragonal from the microscopic viewpoint due to the disordered oxygen vacancy and it is indicated that the self-doping of hole into the CuO2 sheet does not occurred for y>6.66 in contrast with YBa2Cu3Oy (y<6.70).
Ion Implanted Dopant Environments in Amorphous Silicon
Authors: Greaves G. Neville , Dent Andrew J. , Dobson Barry R. , Kalbitzer Siegfried , Müller Gerhardt
Published: March 2014

X-ray absorption fine structure (XAFS) spectroscopy has been measured at glancing angles of incidence on 5×1019 gallium atoms cm-3 ion-implanted in amorphous silicon. The effects of preparation (ion-damaged or rf glow-discharge) of amorphous silicon are discussed. In particular, heat treatment has been investigated to examine the local structure of the dopants at various stages of annealing and recrystallisation.
XAFS Studies of Amorphous Silicon Nitride
Authors: Umesaki N. , Kamijo N. , Tanaka I. , Niihara K.
Published: March 2014

The structure of chemical vapor-deposited (CVD) amorphous silicon nitride (a-Si3N4) has been studied at the Si K-edge by the use of a laboratory XAFS system. The average bond lengths and coordination numbers of the nearest-neighbors Si-N and Si-Si have been determined from the obtained EXAFS data. We discussed the local structure of the a-Si3N4.
Application of a Laboratory XAFS Spectrometer to Characterization of Aluminium in an Amorphous Aluminosilicate
Authors: Ikeda Yoshio , Yokoyama Takushi , Yamashita Seiichi , Wakita Hisanobu
Published: March 2014

Using a Laboratory XAFS(X-ray absorption fine structure) spectrometer, the local structure of aluminium in an aluminosilicate with a Si/Al atomic ratio of 1/3 was studied. From the XAFS data, the average Al-O interatomic distance and coordination number of aluminium atoms were estimated. In addition, the assignment of the XANES(X-ray absorption nearedge structure) spectra for aluminium was discussed based on the 27Al MAS NMR spectra of the corresponding samples.
Lattice Distortion and Ferroelectricity in IV-VI and II-VI Semiconductor Alloys
Authors: Wang Zhihai , Bunker Bruce A. , Mayanovic Robert A. , Debska Ursula , Furdyna Jacek K.
Published: March 2014

Using the x-ray absorption fine structure (EXAFS), we have investigated the local structure of disordered PbSxTe1-x (x=0.10, 0.18, and 0.30) alloys at temperatures ranging from 10 K to 300 K, and ZnxCd1-x Te (x=0.10 and 0.20) alloys at temperatures ranging from 77 K to 250°C. In PbSxTe1-x alloys, the sulphur ions are found to be off-center in both the high and the low temperature phase and Pb sublattice and Te sublattice shift relative to one another below the transition temperature. In ZnxCd1-xTe alloys the zinc ions are found in a slightly asymmetric site in the cages formed by four NN Te ions and no evidence of a relative phase transition is observed. We discuss our results concerning the ferroelectric phase transitions (FPT) induced by off-center ions in these two systems.
XAFS Study on the Solid State Amorphization of a Mechanically Alloyed Nb-Sn Powder
Authors: Nasu T. , Edwards A. M. , Cho Y. , Sayers D. E. , Koch C. C.
Published: March 2014

The structural changes in Nb-Sn mixed powders during solid state amorphization were observed by XAFS. Mechanical alloying of Nb-Sn mixed powders leads to the formation of A15 Nb3Sn which then transform to an amorphous phase. The short range order of the amorphous Nb3Sn alloy is analogous to the short range order of the A15 structure.
EXAFS Measurements for Dense Vapors of Chalcogens and Chalcogenides
Authors: Hosokawa Shinya , Tamura Kozaburo , Inui Masanori , Endo Hirohisa
Published: March 2014

We have measured the EXAFS spectra of dense Se vapor in the temperature-pressure range up to 1600°C and 150 bar. For the measurements we have developed a high-pressure vessel and a polycrystalline sapphire cell of our own design. We have found that dense Se vapor under the present experimental condition consists mainly of Se2. The bond length is much shorter than that of liquid Se, and nearly the same as the data for Se2 in low-density vapor Se obtained by the recent spectroscopic study. When the saturated vapor-pressure curve is approached, the bond is elongated. We have also measured the EXAFS spectra of vapor Te and AsS. We have found the bond length of the molecule in vapor Te is nearly equal to that for Te2 obtained from the spectroscopic data. The structural parameters of the molecules in vapor AsS is similar to those of cagelike AS4S4 molecules in the crystal with a monoclinic form.
Theoretical Investigation of EELFS for a Deep Core Excitation
Authors: Yikegaki Tetsurou , Hayashi Toshinori , Enokijima Toru , Takatoh Shuji , Araki Kiyoaki , Tsukajima Jun'ichi , Fujikawa Takashi
Published: March 2014

The reflection mode EELFS is theoretically investigated. In particular, selection rule and the anisotropy of EELFS are discussed based on the basic EELFS theory developed by one of the authors. In a small angle scattering the dipole selection rule is not so good but the EXAFS phase function can be safely applied to EELFS analysis.
Local Distortion of AsO4 and PO4 Molecules in KDP-Family Crystals
Authors: Noda Yukio , Maeda Hironobu , Terauchi Hikaru , Kasatani Hirofumi , Ogura Kenichiro , Kamon Kazuya , Umeki Takashi , Yoneda Yasuhiro , Murakami Satoshi , Kuroiwa Yoshihiro
Published: March 2014

XAFS experiments around the K-absorption edge of P atoms in KDP and As atoms in KDA were carried out in order to study the existence of local distortion in PO4 and AsO4 molecules. Well defined XAFS signals were obtained up to 18Å-1 in KDA and 14Å-1 in KDP and DKDP. Extraordinary temperature dependence of the higher frequencies in k3 χ (k) of KDA was found, but nothing happened at T
c
. Obtained bond lengths P-O and As-O are consistent with structural analyses. Present experiments suggest that the AsO4 molecule already distorts at the high temperature phase, while it is hardly to conclude that a PO4 molecule is in a disordered state because of the insufficient resolution.
EXAFS Study of NbOPO4-Based Lithium Superionic Conductors
Authors: Chaboy J. , Marziali M. , Stizza S. , Lozano D. , Cantero M.
Published: March 2014

The structural characterization of a new family of ionic conductors obtained by lithium ion insertion into the channels of the NbOPO4 framework has been studied by Extended X-Ray Absorption Spectroscopy. The location of the lithium atoms in these systems has been indirectly inferred through the determination of the position occupied by the oxygen of the lithium hydroxide in these materials.
EXAFS Study of Metallo-Organic Polymers Showing Anomalous Magnetic Behaviour
Authors: Garcia Joaquín , Chaboy Jesus , Marguin Valerie , Castro Cristina , Ramos José , Palacio Fernando
Published: March 2014

The geometrical local structure around the iron atoms of two metallo-organic Schiff-base polymers have been determined by means of iron K-edge EXAFS spectroscopy. First shell analysis shows 6 nitrogen atoms coordinating the metal in a tetragonal distorted octahedric configuration. This result indicates that the anomalous magnetic behaviour observed in this compounds is not intrinsic to the polymeric material itself.
XANES Spectroscopic Studies of Chemical Bonding in Sulfur-Containing Organic Photographic Materials
Authors: Araki Tohru , Seki Kazuhiko , Narioka Satoru , Ishii Hisao , Takata Yasutaka , Yokoyama Toshihiko , Ohta Toshiaki , Okajima Toshihiro , Watanabe Satoko , Tani Tadaaki
Published: March 2014

S and N K-edge XANES spectroscopic study was performed for examining how XANES can be used for clarifying resonance and tautomerism in organic compounds containing thioamide (-NH-CS-) group used as additives in silver halide photography. The N K-edge spectra of all compounds, even N-methyl substituted ones, showed clear N1s → π\ddag peaks, giving a direct evidence of partially double bond character of the C-N bond, and suggesting thioamide structure by its excitation energy. S K-edge XANES spectra of the studied compounds also a clear peak at 2470-1 eV well separated from other peaks, and it is assigned to S1s → π\ddag resonance in thoioketone group by its polarization, effect of substitution at S site, and its energy significantly different from those of thiols. These results showed usefulness of XANES for studying resonance and tautomerism in these compounds, and indicate that all compounds studied, including extraordinarily strong antifoggant mercaptotetrazole, are in the thioamide form.
X-ray K-Absorption Near Edge Structure Studies of Some Mixed Ligand Cobalt (II) complexes
Authors: Gupta Gopal Das , Joshi Santosh Keshav , Shrivastava Basant Deo , Pandeya Krishna Bihari
Published: March 2014

X-ray absorption near edge structure (XANES) measurements have been made on the K-edges of cobalt in the five oximinoacetone thiosemicarbazone (oatsc) complexes of cobalt viz., [(Co(oatsc)2(oAc)2]; [Co(oatsc)2(Br)2]; [Co(oatsc)2(Cl)2]; [Co(oatsc)2(ClO4)2] and [Co(oatsc)2(NO3)2]. These complexes are important from the pharmacological point of view. The present XANES studies reveal that as far as the structure is concerned, the four complexes with (oAc)2, Br2, Cl2 and (ClO4)2 ligands are similar and these ligands are part of the first coordination sphere. In [Co(oatsc)2(NO3)2] we find that one nitrate group is inside the coordination sphere, whereas one nitrate group is out-side the coordination sphere. Our studies establish the relative ionic character in the order [Co(oatsc)2(NO3)2] > [Co(oatsc)2(ClO4)2] > [Co(oatsc)2(Cl)2]> [Co(oatsc)2(Br)2] > [Co(oatsc)2(oAc)2]. The average metal-ligand bond distance have been estimated and explained on the basis of the structures of the complexes.
X-ray Absorption Studies on Aqueous Ionic Solutions in the Liquid and Glassy States
Authors: Yamaguchi Toshio , Wakita Hisanobu , Nomura Masaharu
Published: March 2014

X-ray absorption fine structure (XAFS) measurements have been performed on aqueous solutions of zinc(II) chloride, bromide, and iodide with different solute concentrations in the liquid state at room temperature and in the glassy state at liquid nitrogen temperature. The XAFS data have revealed that predominant zinc(II) halide complexes formed in the solutions differ greatly in the liquid and glassy states. The following equilibrium shift is proposed to take place in vitrification.

2[ZnX2(H2O)2]+2H2O→[ZnX4]2-+[Zn(H2O)6]2+(X=Cl-, Br-, I-)
Anharmonicity of β-AgI Studied by the Cumulant Expansion of EXAFS
Authors: Dalba Giuseppe , Fornasini Paolo , Rocca Francesco
Published: March 2014

EXAFS at the Ag K edge of β-AgI has been measured and analyzed in terms of cumulants in the temperature interval T=23\div410 K. Tests on EXAFS simulated from excluded-volume model distributions have shown that the cumulant series of the Ag–I distance distribution is convergent. The polynomial coefficients extracted from EXAFS analysis reproduce the exact cumulants only below 300 K The distributions obtained from the cumulants are in agreement with the excluded-volume model. The 1st-shell second cumulant (Mean Square Relative Displacement) is largely insensitive to anharmonicity as a consequence of the high degree of correlation of atomic motion.
Polarization Photosensitivity of CuInSe2/CdS Thin Film Heterojunctions
Authors: Konstantinova N. N. , Magomedov M. A. , Rud' V. Yu. , Rud' Yu. V.
Published: March 2014

The phenomenon of polarization photosensitivity of CuInSe2/CdS thin film heterojunctions due to anisotropic transmission of linear polarized radiation (LPR) through the air-CdS polycrystalline film interface was detected. The parameters of polarization photosensitivity are shown as functions of the angle of oblique incidence θ and the incident photon energy LPR. The induced photopleochroism coefficient P increased with increasing angle in accordance with the law P=θ2, and at θ≃80° it reached 64%. As follows from polarization measurements photosensitivity, CuInSe2/CdS thin films heterostructures can be used as broadband LPR photoanalysers.
Photoconductive Imaging Using CuInSe2 Film
Authors: Tanaka Katsu , Kosugi Mitsuo , Ando Fumihiko , Ushiki Takehito , Usui Hiroaki , Sato Katsuaki
Published: March 2014

This paper describes an application for the first time of a vidicon type pickup tube using a chalcopyrite-type semiconductor copper-indium-diselenide (CuInSe2) film as a target for the image sensor. The fabricated sensor shows the horizontal resolution of 600 TV lines indicating that CuInSe2 is one of promising materials for television image pickup device with the high resolution.
Liquid Phase Epitaxial Growth and Characterization of High Quality GaInAsSb/InAs for Photodiodes
Authors: Kan Gong , Yamaguchi Tomuo , Suzuki Isao , Aoyama Mitsuru , Kumagawa Masashi , Rowell Nelson L. , Rinfret Wang
Published: March 2014

The device-quality Ga1-x
In
x
As1-y
Sb
y
/InAs epilayers have been obtained by doping Gd in the growth melt. The optical properties for epilayers were investigated by using Fourier Transform Infrared (FTIR) photoluminescence (PL) measurements. The PL Full Width at Half Maximum (FWHM) as narrow as 4.67 meV have been achieved indicating high quality of epilayers. The excitation density and temperature dependence of PL spectra were studied. The results indicated that wave-vector-conserving transition is valid at room temperature for this material. Photodiodes have been fabricated using p-n junction GaInAsSb epilayers. The dark current lower than 1 µA at 77 K has been realized.
Study of Se–Te–Sb System for Application to Reversible Optical Data Storage
Authors: Mehra R. M. , Kaur Gurinder , Pundir Amit , Mathur P. C.
Published: March 2014

In the present work variation of the two main parameters–viscosity and critical cooling rate, required for the recent upcoming optical data storage devices, have been analysed for different compositions of Se80-x
Sb
x
Te20 (0≤x≤9) system. Temperature dependence of viscosity has been determined using the activation energy for glass transition and for crystallization obtained from heating rate dependence of glass transition temperature and peak crystallization temperature from DSC measurements. Vicsocity has been estimated with the help of Vogel-Tamman-Fulcher equation. It has been found that for samples containing Sb≤4 at.%, the viscosity increases with the increase in Sb content. Further increase in Sb concentration causes a decrease in the viscosity. These results are consistent with the structural changes taking place in the Se–Te system with increase in Sb content. Using these values of viscosity and kinetics of crystal nucleation and growth process, the time-temperature-transformation curves were obtained. The critical cooling rate R

c
is found to increase for Sb>4 at.%. For good reversible phase change optical recording, the critical cooling rate of the material should be high enough so as to get an erasure time of less than 1 µs. From the analysis of the data the suitability of the SeTeSb system for optical recording has been discussed.
Low-Pressure Metalorganic Chemical Vapor Deposition of CuAlSe2 Epitaxial Films
Authors: Chichibu Shigefusa , Shirakata Sho , Sudo Ryo , Uchida Mei , Harada Yoshiyuki , Matsumoto Satoru , Higuchi Hirofumi , Isomura Shigehiro
Published: March 2014

A low-pressure metalorganic chemical vapor deposition of CuAlSe2 epitaxial films was performed using several kinds of metalorganic precursors. The film quality varied remarkably depending on the source precursors. Free exciton emission at 2.739 eV was observed in the CuAlSe2 films grown using triisobutylaluminium and diethylselenium, both of which have lower decomposition temperatures.
Visible Photoluminescence in Undoped and Zn-doped CuAlS2
Authors: Aksenov Igor , Kai Tetsuya , Nishikawa Nobuyuki , Sato Katsuaki
Published: March 2014

Photoluminescence (PL) properties of undoped and Zn-doped CuAlS2 crystals have been studied. The Zn-doped crystals have been found to exhibit several strong emissions in the green-to-violet spectral region, the dominant emission being determined by the concentration of Zn-dopant. On the basis of the detailed PL studies we have determined the activation energies of the donor-like ZnCu- and the acceptor-like VCu-defects, the last result being confirmed by the ESR experiments.
Single Crystal Growth of Cu–III–VI2 Semiconductors by THM
Authors: Miyake Hideto , Sugiyama Koichi
Published: March 2014

The traveling heater method (THM) has been applied to the single crystal growth of Cu–III–VI2 chalcopyrite semiconductors. Up to this time, bulk single crystals of CuGaS2, CuGaSe2, CuInS2 and CuInSe2 ternary compounds have been obtained by the THM technique using In solvent. The THM growth of bulk single crystals of CuGa0.6In0.4S2 quaternary alloy, which is lattice-matched to ZnS, has been investigated. By the use of In-solution zones containing 60 mol% CuGa0.37In0.63S2 solute, single crystals with a uniform composition of CuGa0.6In0.4S2 were obtained.
Electron Spin Resonance Study of CuInSe2 Single Crystals
Authors: Nomura Shigetaka , Takizawa Takeo , Goltzené Alfred , Schwab Claude
Published: March 2014

Imperfections relating to iron contamination in undoped CuInSe2 single crystals have been studied using Electron Spin Resonance at liquid He temperature. A fine structure of the S=5/2 state attributed to Fe3+ has been observed for crystals of Cu/In ∼ 1. On the other hand, some of indium-rich (Cu/In<1) crystals show a single line of g
eff∼10. Fe2+ is one of the possible candidates for this line. The two different ionization states of iron in CuInSe2 suggest that iron atoms substitute copper sites in Cu-deficient system rather than indium sites which are preferably occupied by Fe3+ in nearly stoichiometric system.
Photoemission and X-Ray Absorption Study of La1-xSrxMnO3
Authors: Saitoh Tomohiko , Bocquet Antoine E. , Mizokawa Takashi , Namatame Hirofumi , Fujimori Atsushi , Abbate Miguel , Takeda Yasuo , Takano Mikio
Published: March 2014

The electronic structure of La1-x
Sr
x
MnO3 has been investigated by photoemission and X-ray absorption spectroscopy. The spectra have been analyzed using a configuration interaction cluster model. Deduced parameters show that the band gap of LaMnO3 is of the p-d gap type while that of SrMnO3 has also considerable p-p character. The shift of the Fermi level with doping does not follow the simple rigid band picture. The photoemission spectra of SrMnO3 doped with electrons show the appearance of “in-gap states” in the band gap of SrMnO3.
Ternary Compounds Binding Energies from Atomic Cluster Calculations
Authors: Casula F. , Mula G. , Pirodda M.
Published: March 2014

A recently proposed method for obtaining a priori reliable estimates of bulk binding energies from LDA calculations on small atomic clusters is here extended to chalcopyrites. The results appear in very good agreement with experimental data, thus commending the method to anyone interested in systematic studies on these compounds.
Spin Reorientation of Mn2-xFexSb
Authors: Ito Tadaei , Kanomata Takeshi , Mori Sin-ichi , Hasebe Yuichi , Ishigaki Hidetaka , Abe Shunya , Yoshida Hajime , Kaneko Takejiro
Published: March 2014

The composition and pressure effects on the spin reorientation temperature (T
sr) for Mn2-x
Fe
x
Sb have been measured. The composition dependence of T
sr increases rapidly with increasing x at normal atmospheric pressure. The pressure dependence of T
sr for Mn1.9Fe0.1Sb increases linearly with increasing applied pressure and the value of dT
sr/dp is +3.14 K/kbar. On the basis of the pressure and composition effects on T
sr, the microscopic origin of the magnetic anisotropy of Mn2-x
Fe
x
Sb is discussed.
Pressure Dependence of the Magnetic Phase Transition Temperature in Mn2-xCrxSb
Authors: Endo S. , Wakisaka T. , Ono Fumihisa
Published: March 2014

Pressure dependences of Ms-T (Ms: saturation moment) and magnetisation curves in Cr-modified Mn2Sb system were investigated in the pressure range up to 1 GPa and in the temperature range between 4.2 and 250 K. It was found that there are at least three intermediate magnetic states between the antiferromagnetic (AF) and perfect ferrimagnetic (FR) states. The AF-FR transition temperature decreased with increasing pressure, in contrast to the expectation from the conventional model.
Magnetooptical Spectra in PtMnSb between 1.2 and 5.9 eV
Authors: Ikekame Hiroshi , Sato Katsuaki , Takanasi Koki , Fujimori Hiroyasu
Published: March 2014

Magnetooptical Kerr rotation and Kerr ellipticity were measured on the (111) surface of a single crystal of PtMnSb for photon energies between 1.2 and 5.9 eV. Peak Kerr rotation reaches as large as 120 min of arc in an annealed sample. Real and imaginary parts of off-diagonal conductivity tensor were calculated from the measured spectra. The obtained spectra showed a good agreement with those of polycrystalline bulk samples. The spectrum of imaginary part of off-diagonal conductivity consists of two peaks with opposite signs at 2.5 eV and 5.2 eV, the first peak being resolved into two structures in the annealed crystal. These structures are correlated with band structures.
Magnetic Behavior of Helical Magnet Fe0.8Co0.2Si
Authors: Ishimoto Kenichi , Yamauchi Hiroshi , Ohashi Masayoshi , Yamaguchi Yasuo
Published: March 2014

Magnetic measurements were carried out for long period helical magnet Fe0.8Co0.2Si under the magnetic field up to 20 kOe for the temperature range from 4.2 K to 60 K. The long period spin structure is shown to be fixed along any direction of the crystal. The magnetic behaviors are explained by a theory including the antisymmetric exchange interaction in B20 crystal structure.
Electrical Conductivity of Nickel Phosphides
Authors: Shirotani Ichimin , Takahashi Eiji , Mukai Naoki , Nozawa Kiyokazu , Kinoshita Minoru , Yagi Takehiko , Suzuki Kazuya , Enoki Toshiaki , Hino Syojun
Published: March 2014

Five nickel phosphides, Ni2P, NiP, NiP2, NiP2 (high pressure form) and NiP3 which have interesting crystal structures have been prepared at high temperatures and high pressures. The electrical resistivity, dc magnetic susceptibility and photoelectron spectrum of nickel phosphides have been studied. Five nickel phosphides show the metallic behavior though their crystal structures and Ni–Ni distances are remarkably different. The relationship between the crystal structures and physical properties of the nickel phosphides is discussed.
Electronic Structure and Magnetic and Optical Properties of NiAs-type Transition-Metal Chalcogenides MX (M=Fe, Co; X=S, Se)
Authors: Ikeda Hiroaki , Shirai Masafumi , Suzuki Naoshi , Motizuki Kazuko
Published: March 2014

Electronic band structure calculations are performed for MX (M=Fe, Co; X=S, Se) with the ideal NiAs-type structure by using a linearized augmented-plane-wave (LAPW) method. The denstity of states (DOS) at the Fermi level in the non-magnetic state is significantly reduced with decreasing the lattice constant c. This result is consistent with the fact that FeS (or Fe7Se8) having a larger c value shows a magnetic ordering, while CoS (or Co7Se8) dose not. In the optical conductivity calculated by neglecting the transition matrix elements, a prominent peak is found at 0.5 eV for FeSe, while a broad hump exists around 1.5 eV for CoSe. The results show good correspondence to experimental data obtained for Fe7Se8 and Co7Se8.