bluuebunny/crossref_metadata_2025 huggingface dataset:
Investigation of silicon grain structure and electrical characteristics of TFTs fabricated using different crystallized silicon films by atmospheric pressure micro-thermal-plasma-jet irradiation
Authors: Hayashi Shohei , Morisaki Seiji , Kamikura Takahiro , Yamamoto Shogo , Sakaike Kohei , Akazawa Muneki , Higashi Seiichiro
Published: March 2014

Amorphous silicon (a-Si) films were crystallized using three grain growth modes induced by micro-thermal-plasma-jet (µ-TPJ) irradiation and applied to the channel regions of thin-film transistors (TFTs). Solid phase crystallization (SPC) formed microcrystalline grains and showed a lower crystallinity of 70%, whereas leading wave crystallization (LWC) and high-speed lateral crystallization (HSLC) formed significantly larger grains than the TFT channel region. The SPC-TFT showed a lower field-effect mobility (μFE) due to the small grain size and the existence of many grain boundaries, whereas LWC- and HSLC-TFT channels were formed by only single grains and showed a μFE higher than 300 cm2 V−1 s−1 in the n-channel. The defect density of HSLC was smaller than that of LWC; consequently, the HSLC-TFT performed better than the LWC-TFT. The maximum μFE values of n- and p-channel HSLC-TFTs were 418 and 224 cm2 V−1 s−1, respectively.
Three-dimensional confocal imaging for breast cancer detection using CMOS Gaussian monocycle pulse transmitter and 4 × 4 ultra wideband antenna array with impedance matching layer
Authors: Sugitani Takumi , Kubota Shinichi , Hafiz Mohiuddin , Xiao Xia , Kikkawa Takamaro
Published: March 2014

A time-domain reflectometry breast cancer detection system was developed, which was composed of a Gaussian monocycle pulse (GMP) transmitter circuit fabricated by complementary metal oxide semiconductor (CMOS) 65 nm technology and an ultra wide-band (UWB) planar slot antenna array. The center frequency and bandwidth of the antenna were 6 and 9.2 GHz, respectively. The GMP train having the pulse width of 160 ps was generated by the 65 nm CMOS logic circuit with a core area of 0.0017 mm2 and was emitted by the 4 × 4 planar slot antenna array. The fabricated planar 4 × 4 antenna array with the matching layer could resolve the two separate 5 × 5 × 5 mm3 breast tumor phantoms, which were located at the depth of 22 mm with the spacing of 8 mm.
Cu2ZnSn(S,Se)4 thin film solar cells using printing and high-pressure sintering process
Authors: Gao Feng , Maeda Tsuyoshi , Wada Takahiro
Published: March 2014

We fabricated Cu2ZnSn(S,Se)4 (CZTSSe) solar cells by a screen printing and high-pressure sintering (PHS) process. CZTSSe powders with a Cu-poor and Zn-rich composition of Cu1.9Zn1.25Sn(S0.4Se0.6)4.5 were synthesized by mixing the elemental powders and post-heating at 200–600 °C. Then, we fabricated CZTSSe films by PHS. The obtained CZTSSe films were post-annealed at 550–600 °C for 10 min under various atmospheres. The CZTSSe solar cell with a device structure of Ag/indium tin oxide (ITO)/i-ZnO/CdS/CZTSSe/Mo/soda-lime glass showed an efficiency of 2.63%, with an open circuit voltage (V
oc) of 372 mV, a short circuit current density (J
sc) of 18.7 mA/cm2, and a fill factor (FF) of 37.8%.
SAW Device Simulation Using Boundary Element Method
Authors: Hashimoto Ken-ya , Yamaguchi Masatsune
Published: March 2014

The paper has attempted to employ the expansion functions of the charge distribution on an electrode proposed by Skeie and Rønnekleiv for the boundary element method (BEM) analysis of interdigital transducers (IDTs). The accuracy and extremely rapid convergence of the analysis were confirmed by the calculation of static capacitances for several types of IDTs. The analysis was also applied to the characterisation of a floating electrode unidirectional transducer with a large number of electrodes. This confirmed that BEM mentioned in the present paper could be used as an effective tool for SAW device simulation.
Study on SAW Streaming and its Application to Fluid Devices
Authors: Shiokawa Showko , Matsui Yoshikazu , Ueda Toshihiko
Published: March 2014

Various liquid motions such as streaming and droplet formation on the surface of SAW propagation substrate are called SAW streaming. Experiments on SAW streaming using 128° rot.
Y–X LiNbO3 at the frequency of 50 MHz with various pulse widths are described. Surface treatment of SAW substrate by silanization is employed to demonstrate the droplet ejection. Theoretically, SAW streaming force can be derived using the acoustic streaming theory. The calculated SAW streaming force is found to be very large and strong enough to expel a droplet from a liquid surface.
Measurement of Velocity and Viscosity of Liquid Using Surface Acoustic Wave Delay Line
Authors: Nomura Tooru , Yasuda Tsutomu
Published: March 2014

There is increasing use of surface acoustic wave (SAW) in sensors, and the majority of the work reported on sensors to date has used Rayleigh waves on piezoelectric materials. In this paper, a leaky SAW delay line was used for measuring the acoustic properties of liquids. The leaky SAW with the shear horizontal displacement is excited on a piezoelectric substrate using interdigital transducers. The velocity and viscosity of liquids are measured using the leaky SAW delay line. Experiments are made with a rotated Y cut LiNbO3 substrate. Results shown that the method is very suitable for sensing liquid.
Propagation Characteristics of A0 Mode Leaky Lamb Wave Having Phase Velocity Close to Liquid Sound Velocity
Authors: Osuga T. , Ushiama S. , Toda K.
Published: March 2014

Characteristics of A
0 mode leaky Lamb waves propagating along a liquid-solid interface are numerically analyzed. In the phase velocity region close to the liquid sound velocity, the dependences of the phase velocity deviation and the damping ratio on the liquid state variables of density, volume elasticity and viscosity are investigated. The leaky wave radiation becomes the maximum at the critical frequency where the phase velocity of the A
0 mode Lamb wave is equal to that of the liquid sound. The phase velocity deviation takes the peak value in the vicinity of the critical frequency.
Quadrature Phase Shift Keying Modulation and Demodulation System Using Rayleigh Wave Devices
Authors: Ikeda Toshio , Furusawa Masami , Toda Kohji
Published: March 2014

Surface acoustic wave devices are incorporated to realize a quadrature phase shift keying system. The signal processing device using the Rayleigh wave consists of four delay lines with different acoustic phase delays on one substrate surface and generates a quaternary phase shift keyed rf signal corresponding to an input quarternary impulse train. The SAW device in the demodulation possesses an additional function for phase comparison. Experimental results at the carrier frequency of 125 MHz are presented and are in good agreement with the operation principle.
SiO2/36° Y-X LiTaO3 Surface Acoustic Wave Resonator
Authors: Satoh Kiyoshi , Fujiwara Yoshiro , Hashimoto Kazushi
Published: March 2014

SiO2/36° Y-X LiTaO3 substrate which has an excellent characteristic of temperature and a high electro-mechanical coupling coefficient is realized. Temperature coefficient of frequency (TCF) is zero and electro-mechanical coupling coefficient (K2) is 5.2% when thickness of SiO2(H/λ) is 21%. Using this resonator, a voltage controlled oscillator (VCO) with excellent temperature characteristic and wide frequency deviation larger than 800 ppm/V is obtained.
Improvement of Magnetic Properties of Iron-Boron Films by Hydrogen Mixing in Sputtering Gas for Magneto-Surface-Acoustic-Wave Media
Authors: Tsuboi Yoshihiro , Yokokawa Narutoshi , Inoue Mitsuteru , Fujii Toshitaka
Published: March 2014

In the construction of excellent magneto-surface-acoustic-wave (MSAW) devices utilizing magnetostrictive films, MSAW media must satisfy two contradictory requirements of large magnetostriction and high magnetic permeability simultaneously to ensure large magneto-mechanical coupling. For this purpose, hydrogen mixing in argon sputtering gas is found to be effective to improve magnetic properties in rf-sputtered amorphous Fe–B films. Preliminary results of MSAW characteristics fabricated by this method are also described.
An Ultrasonic Motor Using a Shear and Bending Mode of a Disk Resonator
Authors: Iwao Naoto , Yamaguchi Masaki , Yamada Shoji
Published: March 2014

Torque, revolutions and efficiency are investigated in a new type ultrasonic motor with a disk resonator using a shear mode to generate a driving force and a bending mode to control a friction force. The condition that these two modes have the same resonant frequency is realized by adjusting the disk resonator thickness and the contacting force against the disk resonator. The revolutions measured under load free and the restraining torque were to be 18 r.p.m. and 2.5 kgf·cm, respectively. The maximum efficiency was 2% at the output torque of 1.6 kgf·cm.
Measurement of Electric Field Distributions in Solid Dielectrics Using Ultrasonic Waves
Authors: Maeda Masataka , Takada Tatsuo , Ide Masao
Published: March 2014

An acoustic step-wave probing technique using ultrasonic waves was used to investigate electric field distributions in solid dielectrics. The acoustic step-wave was generated by means of a piezoelectric transducer. The electric field distributions were measured in three kinds of samples: Teflon, polyethyleneterephtharate (PET) and high-density polyethylene (HDPE). Differences in the shape of distorted electric field distributions were observed for each material due to the injected charges and the polarization charges.
Analysis of Pressure Sensitivity of a Tuning-Fork-Type Quartz Vacuum Gauge
Authors: Ito Hideaki , Nakazawa Mitsuo , Goto Susumu , Takahashi Yo
Published: March 2014

Research on the pressure sensitivity of a tuning-fork-type quartz resonator was conducted experimentally and theoretically. As a result of analysis, we could predict the size effects and the cut angle dependence on the enhanced pressure sensitivity of a quartz vacuum gauge. The experiments conducted using the newly designed quartz resonators with a variety of frequencies were found to be in good agreement with the theoretical predictions.
An Instantaneous Echography by Ultrasonic Fan Beam
Authors: Mizuta Mamiko , Chihara Kunihiro , Shirae Kimisuke
Published: March 2014

A new ultrasonic imaging method to obtain an instantaneous echogram is described. This method is developed to detect the object image without scanning by a pulsed fan beam. The experiments are made on copper wires, a vinyl sheet and a sponge in a water vessel. The results show that spot objects can be detected by this method and that projecting multipulse at high frequency and lengthening aperture are effective to improve the image of a plane object and a voluminous object.
Observation of Layered Structure Utilizing Wavelength Dependence of Photoacoustic Signal
Authors: Nagata Yoshihiko , Yamanaka Kazushi' , Koda Toshio
Published: March 2014

A photoacoustic effect dependent on wavelength is studied using a dye laser system. The wavelength of this laser system to induce a photoacoustic signal can be arbitrarily selected between 570 nm and 720 nm. Some samples with a layered structure were evaluated using this system. Wavelength dependence and images of the photoacoustic signal obtained by experiments present the possibility that the layered structure of the sample is separately observed in each layer.
Consideration on PA Signals of Multilayer Structure Measured by PAS Using Transparent Transducer
Authors: Horita Susumu , Yagi Syuichi , Hata Tomonobu
Published: March 2014

We measured the spectral dependence of photoacoustic(PA) signal for Ga
x
In1-x
P/GaAs heterostructure by PA spectroscopy (PAS) using a transparent transducer, LiNbO3. Between two layers a sharp dip of PA signal was observed which corresponded to the absorption edge. We discussed the generation mechanism of this PA dip qualitatively and speculated that it was caused by the difference of thermal expansion coefficient between the two layers, that is, a bimetal effect. This indicates that the thermal expansion coefficient is important in the analysis of the PA signal of a multilayer structure.
Acoustic Spectral Hole Burning by a Dislocation Mechanism
Authors: Tsuruoka Fujio
Published: March 2014

Acoustic spectral hole burning was successfully introduced into deformed piezoelectric powders by the application of a large amplitude pulsed electric field at the specimens' resonant frequency. Decrement obtained from the difference between the damping constants of the deformed and as received particles showed a broad peak in its frequency dependence and was well described by the theory based on vibrating dislocations. It was considered that dislocations multiplied, cut each other and pinning length decreased, thereby reducing the damping coefficient which was detected as a hole in the absorption spectrum.
Overtone-Drive in Marx's Composite Oscillator Method
Authors: Tateno Hiroto , Iwashita Youichirou
Published: March 2014

We developed Marx's composite oscillator method to an automatic control system to keep the strain amplitude constant at fundamental and third overtone frequency. Stability of this control system is analyzed by an automatic control theory in the measurement of internal friction with varying strain amplitude, temperature, and external field. It is applied to measurement of a relaxation peak at a fundamental frequency of 50 kHz and overtone 150 kHz of the same specimen to study the relaxation process of AgCl.
Fatigue Test of Piezoelectric Ceramics under High Hydrostatic Pressure
Authors: Takahashi Sumio , Okajima Katsunori , Hasegawa Akio
Published: March 2014

The fatigue strength of a piezoelectric ceramic material was measured under hydrostatic pressure up to 40 MPa by using an ultrasonic vibration system. Fatigue strength increased with hydrostatic pressure, but the increase for the poled sample was small compared with that for the virgin sample. Also, the fatigue strength of the poled sample was lower than that of the virgin sample. These differences are considered to be due to the anisotropy caused by polarization.
Multiple Scattering Effects of Doublet Cavities in Rubber
Authors: Matsunaga Ryoji , Kikuchi Toshiaki , Hasegawa Akio , Takahashi Sumio
Published: March 2014

Multiple scattering effects of spherical doublet cavities in rubber are described. Transmitted sound fields of a rubber plate including doublet cavities are measured in a water tank and the resonance frequency of these cavities is obtained. The effects of cavity radius and doublet spacing on the resonance frequency are determined. Theoretical and experimental studies have confirmed that the vibration of doublet cavities is greatly affected by multiple scattering waves, and this result will be useful in designing an underwater sound absorber.
Driving and Controlling of a Watch Device Ultrasonic Motor by Two Phase Pulse Signals
Authors: Kusakabe Chiharu , Takano Takehiro , Tomikawa Yoshiro
Published: March 2014

A drive and control system of a light-load ultrasonic motor for a watch device is described. The ultrasonic motor is driven with two phase pulse signals having π/2 phase differences and 50% duty cycles. An angular displacement is detected by a rotary encoder and a rotor moves a 6 deg. step per second.
The experimental results using the system have proved that the light-load ultrasonic motor can be used as a stable stepping motor for a watch device.
Non-Contact Excitation of Vibration Piece Using YAG Laser
Authors: Kurosawa Minoru , Hayashi Tadashi , Wang Ning , Ueha Sadayuki
Published: March 2014

Displacement distributions of flexural and longitudinal vibration pieces are scanned by laser beam to determine the optimum excitation conditions of vibrations. The vibration amplitude is proved to depend on the irradiation position, especially on the moment distribution of flexural vibration and the stress distribution of longitudinal vibration. This means that the acoustic source excited by a laser beam can be treated as a good point source. Conversion efficiency is also proved to be proportional to the power of the laser, and measured as 10-7–10-5%.
Study of Glass Transitions of PG/EG Solutions by Photoacoustic Method
Authors: Koketsu Tomoyuki , Takahashi Eiji , Kanayasu Masanori , Suzuki Tetsuro , Kojima Seiji
Published: March 2014

The relaxation properties of glass transitions were studied in solutions of propylene glycol and ethylene glycol by frequency dependent photoacoustic measurements. The parameters of the Vogel-Fulcher law were determined, and the complex specific heat was analyzed by the Cole-Cole plot. The parameter of the Davidson-Cole formula was found to decrease as the ratio of propylene glycol decreased.
An Attempt to Observe Nuclear Fusion in Titanium by Internal Friction
Authors: Tateno Hiroto , Iwashita Youichirou
Published: March 2014

Internal friction and Young's modulus were measured in a deuterium-absorbed titanium rod during the heating process from liquid nitrogen temperature, but no change was observed at 30 °C, the point at which neutrons were detected by a Los Alamos group. An internal friction peak was observed at -70 °C.
Finite Element Analysis of Focusing Field in Nonlinear Acoustic Waves
Authors: Tsuchiya Takao , Kagawa Yukio
Published: March 2014

A finite element approach to focusing field calculation in nonlinear acoustic waves is proposed. Under the assumption of weak nonlinearity, a linearized equation for the second harmonic wave is discretized for finite element method in space including the nonlinearities due to both particle velocity and sound pressure. Numerical experiments confirm that the present method is valid for the analysis of focusing source with large aperture angle. The diffraction of the second harmonic field depends on the nonlinearity parameter B/A.
Measurement of Piezoelectric Vibration Using Optical Fiber
Authors: Ohki Michio , Shima Naomi , Shiosaki Tadashi
Published: March 2014

Fiber optic measurement of piezoelectric vibration and evaluation of the piezoelectric material are described. The sample is a cylindrical piezoelectric transducer around which a fiber is wrapped many turns. Interaction between optical waves traveling in the fiber and the piezoelectric vibration leads to the measurement. As a result, the value corresponding to the piezoelectric constant d can be measured as 1.06×10-10 m/V, which is nearly in agreement with the nominal value of the material, -1.03×10-10 m/V.
Examination of the Fidelity of Acoustic Phase Conjugate Waves Using Schlieren Visualization Technique
Authors: Ohno Masahiro
Published: March 2014

The acoustic phase conjugate wave was generated at 56 MHz by nonlinear electroacoustic interaction in LiNbO3 and its field distribution was visualized with schlieren technique. The field of the phase conjugate wave was very similar to that of the incident wave. The time-reversal property of the phase conjugate wave was verified.
Tissue Hardness Measurement Using Ultrasonic Radiation Force –Theoretical Derivation of Tissue Hardness from the Relaxation Curve–
Authors: Sugimoto Tsuneyoshi , Ueha Sadayuki , Itoh Kouichi
Published: March 2014

In order to establish the theoretical background of a new measurement technique of tissue hardness, the characteristic value of hardness is derived from the force-relaxation curve. Using both the viscoelastic model and the Hertz's contact theory, a viscoelastic diagram is introduced. Hardness measurement of several specimens including human organs has been carried out to obtain these diagrams. These diagrams show characteristic correlation for each organ. Almost the same diagram is proved to be obtained without measuring the absolute value of deformation and/or stress. These facts
suggest that the proposed method can be used in vivo.
A Dual Frequency Ultrasonic Probe
Authors: Saitoh Shiroh , Izumi Mamoru
Published: March 2014

A dual frequency probe using a multilayer ceramic is proposed for simultaneously obtaining a high resolution B mode and a high S/N Doppler mode image. This ceramic consists of 2 layers in which the poling directions are opposite and the individual thicknesses are different. It has been shown that the intima of the carotid artery can be distinguished by an actually fabricated probe with dual frequencies of 3.75 and 7.5 MHz. Also, the S/N of this probe in the Doppler mode has been improved as much as 5 dB over that of a conventional one at the popliteal artery located 5 cm deep from the surface.
Lamb Wave Devices Employing ZnO-Film/Al-Foil Composite Structure
Authors: Rajendran Velayutham , Koike Masakazu , Hashimoto Ken-ya , Ryamaguchi Masatsune
Published: March 2014

The paper proposes Lamb wave devices employing ZnO-film/Al-foil composite structure for the application to liquid and gas sensors. Theoretical analysis suggested that in particular, the velocity of the lowest-order antisymmetrical A
o mode is significantly reduced by loading liquids, which is mainly due to the mass-loading effect. This was experimentally confirmed from the centre-frequency shift in water-loaded devices. It is concluded that devices based on A
o mode possess the possibility of developing a mass-density sensor in liquids.
Resonant Frequency Deviation of Ultrasonic Flat Motor Caused by Rotor Pressure
Authors: Iijima Tamotu , Sano Kazuhide , Shibata Isao , Nakagawa Yasuhiko , Ito Hiroshi
Published: March 2014

The resonant frequency deviation of a ultrasonic flat motor is caused by rotor pressure applied to a plate. In this paper the relation of frequency deviation to contact position and pressure of a rotor is qualitatively studied through the dimensional analysis and the perturbation method. It is confirmed that the frequency deviation is in proportion to displacement amplitude of a contact point and the square root of rotor pressure.
Ultrasonic Rotary Motor Using a Longitudinal-Torsional Vibration Converter
Authors: Tsujino Jiromaru , Takeuchi Masanobu
Published: March 2014

Characteristics of ultrasonic rotary motors using a converter from longitudinal vibration to torsional one are studied. The longitudinal-tortional vibration converter consists of (1) cylindrically arranged thin rods bent at a longitudinal node part, (2) a cylinder with a diagonally slitted vibration converting part, (3) a slitted converting disk and cylindrical parts joined with a bolt. Ultrasonic motors consist of such a converter mentioned above with a driving part at its free edge and a rotor part clamped statically to a driving surface with corned disk springs. Maximum torque over 80 kgf·cm is obtained using the converter of 40 mm diameter.
Development of Fast and Fine Position Control System of an Ultrasonic Motor
Authors: Aoyagi Seiji , Oda Takahiro , Kamiya Yoshitsugu , Okabe Sakiichi
Published: March 2014

This paper shows experimentally that an ultrasonic motor has an approximate first-order transfer function between phase shift input and rotational speed output. A position control system which feedbacks position and velocity involving integral control action was developed. A fast response of about 100 msec and fairly high positioning accuracy up to a rotary encoder resolution were both realized in this system.
Ultrasonic Study of Sub β Relaxation in Epoxides Cured with Aliphatic Diamines
Authors: Matsukawa Mami , Tanaka Yuko , Tanaka Toshimitsu
Published: March 2014

In the bisphenol A-based epoxy resin made from different length prepolymers and Aliphatic Diamines, sub β relaxation were investigated. Low frequency dynamic and ultrasonic results suggest that the relaxation seems to follow Arrhenius type behavior. In addition, the β relaxation is observed separately from the main α relaxation in the MHz range. The strength of β relaxation depends on the molecular length of prepolymer and the amount of curing agent used. This indicates that the relaxation arises from motion within an internal side group containing crosslinks.
Analysis of MSW Transducer Electrode Design by Use of Weighting Functions
Authors: Koike Takuro , Miyahara Masashi
Published: March 2014

We theoretically analyzed MSW transducer electrode design by use of weighting functions. The method is based on the general equivalent circuit model for the MSW devices we developed and extended earlier. The position of each electrode and the geometrical factor are weighted spatially using a function whose Fourier transform is a square pulse in the k domain. This technique is very effective in the design of an MSW filter with a flat frequency response. The method may be extended to various signal processing applications in the future.
X-Ray Photoacoustic Spectroscopy of CuCl, CuBr, and CuI
Authors: Toyoda Taro , Masujima Tsutomu , Shiwaku Hideaki , Ando Masami
Published: March 2014

The hard X-ray absorption spectra of CuCl, CuBr, and CuI have been measured at X-ray absorption near-edge structure (XANES) regions with a photoacoustic detector using synchrotron radiation. These spectra were compared with optical density of X-ray spectra. It is shown that the information derived from XANES is also included in the X-ray photoacoustic spectrum which reflects the heat production processes in those Cu compounds. However, the results showed that the increases and changes of the photoacoustic signal were different from those of the X-ray absorption coefficient at XANES regions.
Study on Orientational Motion of Liquid Crystals by Acoustically Induced Birefringence
Authors: Koda Shinobu , Koyama Takahiro , Enomoto Yuji , Nomura Hiroyasu
Published: March 2014

The acoustically induced birefringence of 4-metoxy-benzilidene-4-n-butylaniline was measured above the temperature of the nematic and isotropic transition point. The birefringence obtained increased lineally with the square of the ultrasonic power and decreased with increasing temperature. The average orientational relaxation time was estimated from the analysis of the time dependence of the birefringence.
Optical Beating Brillouin Spectroscopy
Authors: Matsuoka Tatsuro , Sakai Keiji , Takagi Kenshiro
Published: March 2014

A new technique for Brillouin scattering method which is based on the optical beating spectroscopy was developed and its validity was illustrated. Distinctive features of this system are the very high resolution and the precise measurement of phonon frequency. The frequency resolution is better than 1 MHz: i.e. hundred times higher than the conventional Brillouin Scattering experiment made with Fabry-Perot interferometer.
Measurement of Sound Velocity in Liquid Using Frequency Sweeping-Interdigital Transducer
Authors: Sawaguchi Akihiro , Toda Kohji
Published: March 2014

A system for measuring the sound velocity in a liquid is described, which uses an interdigital transducer (IDT) for a leaky surface acoustic wave. The IDT on a piezoelectric substrate effectively operates as a radiator and a detector of the bulk wave at a liquid-solid interface. The measurement is accomplished by a frequency sweeping method under the condition of the fixed sound path length. The output curve is obtained as a function of the frequency at the IDT in the form of the interference between the input and the output signal reflected from the reflector. The measurement resolution of the
present system is within 0.1%.
Application of Laser-Induced GHz Surface Acoustic Waves to Evaluate Ion-Implanted Semiconductors
Authors: Nishimura Hiroyuki , Harata Akira , Sawada Tsuguo
Published: March 2014

The transient reflecting grating method has been used to characterize ion-implanted silicon layers and demonstrate its usefulness for nondestructive and remote evaluation of modified solid surfaces. The surface acoustic velocity, relaxation constant and signal intensity were measured as functions of ion dose. The results suggested that damage induced by implantation significantly affected the surface properties even under light dose conditions. The subnanosecond temporal resolution of the present method provided successful characterization of the implanted layers.
X-ray Absorption Study of Gallium Arsenide at the Ga and As K-edges
Authors: Dalba Giuseppe , Diop Djibril , Fornasini Paolo , Kuzmin Alexei , Rocca Francesco
Published: March 2014

We present X-ray absorption study of gallium arsenide at the Ga and As K-edges. The analysis of the X-ray absorption fine structure was done in the framework of the multiple-scattering theory. Both XANES and EXAFS regions are considered. The calculated signals are in very good agreement with experimental data. It is shown that for both edges multiple-scattering contributions are negligible for wavevector values greater than 3 Å-1, and single-scattering analysis can be used without significant loss of accuracy in that region.
Study of the Near Edge Background Determination in the Alkali Halides
Authors: Līviņ\us P. , Ingalls R. , Rehr J. J.
Published: March 2014

In order to test theoretical calculations of near edge XAFS, as well as obtain the information therein, methods to determine reliable near edge XAFS backgrounds need to be investigated. We study a promising background determination approach, suitable for the alkali halides, which analyses data at various temperatures and utilizes the low r Fourier components out to and including the first shell radial distances.
An Improved Background Removal Method for XAFS
Authors: Newville Matthew , Līviņ\us Pěteris , Yacoby Yitzhak , Rehr John J. , Stern Edward A.
Published: March 2014

A new technique for separating the background, µ0, from the XAFS, χ, is presented and shown to be an improvement to standard background removal methods, especially in the near-edge region. The technique optimizes the low-R components of \tildeχ(R) For a calculated absorption spectrum for pure Ti, the µ0 found by the presented technique agrees well with the calculated background function. For pure Pb, the extracted µ0 is shown to be nearly the same as that measured from the temperature dependence of the full absorption spectrum starting at an energy in the absorption edge. The reliability of the background from the new method at low-k values allows more information from the XAFS spectra to be used and provides an opportunity for sensitive tests of theoretical calculations in the near-edge region.
“Ab initio” Molecular Orbital Theory of X-ray Absorption Spectra of Simple Molecules and Transition Metal Complexes
Authors: Kosugi Nobuhiro
Published: March 2014

Some results of the ab initio SCF (HF) and CI methods are shown for the bound-state and quasi bound-state resonances of the inner-shell absorption spectra of SF4, CuCl2 and O2, We will discuss the bond-angle and bond-length dependence, the final-state (core-hole screening) effect, the ligand-field effect, and the exchange interaction.
Reduced Core Hole Lifetime Broadening in Auger Final State Yield Spectra
Authors: Drube W. , Lessmann A. , Materlik G.
Published: March 2014

The core hole lifetime broadening is a major limiting factor against achieving high energy resolution in the near-edge absorption region for deep inner shells. This broadening can partly be overcome by measuring highly energy resolved fluorescence radiation, as has been recently demonstrated. An analoguous effect is observed in Auger electron yield spectra. Examples are presented for the L
3-edges of Pd and Ag metal.
How Quick is QEXAFS?
Authors: Frahm R. , Wong Joe
Published: March 2014

The key experimental parameters associated with the quick-scanning EXAFS (QEXAFS) technique have been examined systematically to arrive at a critical evaluation of the “speed limit” of this technique. With current technology, a 1000 eV EXAFS scan can be measured in 5-20 seconds, and a 100 eV XANES spectrum in 1-2 seconds, depending on the crystal monochromator used and actual energy range to be scanned. Further development is needed to achieve sub-second time resolution with this technique.
The Mechanism of Ion Desorption from H2O/Si(100) by O 1s Electron Excitation
Authors: Ikeura Hiromi , Sekiguchi Tetsuhiro , Tanaka Kenichiro , Obi Kinichi , Ueno Nobuo , Honma Kenji
Published: March 2014

The photon stimulated ion desorption (PSID) of H2O on the Si(100) surface has been studied in the photon energy region of 500-750 eV. Not only H+ but also O+ ion was observed. PSID yield curves of these ions indicate characteristic behavior near and above the O K edge; H+ ion exhibits sharp rises at ca. 530 eV and two broad peaks below (ca. 533 eV) and above (ca. 555 eV) the O K-edge, O+ exhibits a delayed threshold at ca. 570 eV and gradual increase up to 700 eV. The O KVV auger electron yield curve, the photoion-photoion coincidence spectrum and the gas-phase photo fragment ion spectrum have also been obtained and compared with the PSID curves. The results are consistent with a mechanism of formation of multiple charged OHm+ (m≥3) ions followed by reneutralization of the excess of charge with strong interactions with the substrate and finally desorption as single charged H+ and O+ ions.
Theory of EXAFS and Comparison with Experimental Data
Authors: Guy Dmitrii E. , Grebennikov Vladimir I. , Ruts Yurii V. , Sentemov Sergei P. , Sokolov Oleg B.
Published: March 2014

An analytical expression for an EXFAS oscillating part was obtained. Model spectra with taking into account of PDS oscillations of intermediate and final states were built up. The comparison between model and experimental oscilating parts were performed.
Circular Magnetic X-ray Dichroism: a Sum Rule
Authors: Carra Paolo
Published: March 2014

A magneto-optical sum rule is derived for circular magnetic dichroism in the X-ray region. It relates the integral of the dichroic signal, over a single partner of a spin-orbit split edge, to the ground state expectation value of the orbital angular momentum, spin and magnetic dipole operators. Applications are discussed to the ferromagnetic metals Fe, Co and Ni.
Magnetic Circular Dichroism at High Magnetic Field and Low Temperature
Authors: Sainctavit Ph. , Lefebvre D. , Arrio M.-A. , Moulin Ch. Cartier dit , Kappler J.-P. , Schillé J.-Ph. , Krill G. , Brouder Ch. , Verdaguer M.
Published: March 2014

The asymmetric wiggler inserted since the end of 1990 on the Super-ACO storage ring in Orsay, has been built to produce high rate and high flux of circularly polarized soft X-rays in the 400-2000 eV range. This insertion device is particularly well suited to measure x-ray absorption spectra corresponding to dipole transitions towards electronic orbitals which are directly responsible for the magnetism (3d states of first row transition metals, 4f states of rare-earths). We report the first magnetic circular x-ray dichroism spectra obtained with this insertion device. They exemplify the wide prospects of this experimental setup.
Theoretical Description of the Magnetic X-ray Dichroism in Diluted and Concentrated Transition Metal Alloys
Authors: Ebert Hubert
Published: March 2014

Recently we have developed a rigorous theoretical description of the magnetic dichroism in the absorption of X-rays (MXD) based on the fully relativistic version of the Korringa-Kohn-Rostoker (KKR) method of band structure calculation. It is shown that an extension of our approach to deal with diluted and concentrated alloys is straightforward and accounts properly for the component-specific nature of.the X-ray absorption process. This has been demonstrated by calculating the MXD spectra of a number of nonmagnetic elements dissolved as impurities in ferromagnetic Fe. Comparison with corresponding experimental data resulted in very satisfying agreement. This also holds for concentrated transition metal alloys of the systems Fe
x
Co1-x
and Fe
x
Pt1-x
.
Dichroism in X-ray Fluorescence
Authors: Strange P. , Hague C. F. , Mariot J.-M. , Durham P. J. , Gyorffy B. L.
Published: March 2014

We discuss circular dichroism in the x-ray fluorescence spectra of magnetic systems in the light of a recent theory1). Fully relativistic local spin density functional calculations on the L2,3 edges of ferromagnetic iron are compared with very recent experimental data, and the relationship between the dichroism spectra and the spin-resolved local density of occupied states is discussed.
Magnetic Dichroism at Fe K- and Gd L3-edges in Gd/Fe Multilayered Films
Authors: Itoh F. , Nakamura M. , Sakurai H. , Kiriake H. , Nawat M. , Honda S. , Kawata H.
Published: March 2014

Circular magnetic X-ray dichroism at Fe K- and Gd L3-edges were measured for magnetic artificial multilayered films of Fe/Gd and the origin of the so-called spin-flop phenomena is discussed.
EXAFS Studies on the Adsorption Structures of P/Ni(111)
Authors: Asakura Kiyotaka , Konishi Shigeru , Ohta Toshiaki , Kitajima Yoshinori , Kuroda Haruo
Published: March 2014

We have studied the local structure around the phosphine adsorbed on the Ni(111) surface at room temperature that shows amorphous structure in LEED observation. The P-Ni distance is about 2.23 Å. The angular dependency of EXAFS demonstrates that the Ni surface is locally reconstructed to the rectangular unit cell structure and P is located almost at the center of a rectanglular plane of 4 Ni atoms. The local structure is the same as that of the annealed P/Ni(111) surface. The annealing treatment produces a long-range order.
Nitrogen Adsorption Induced Reconstruction of Ni(111) Studied by Near Edge X-ray Absorption Fine Structure
Authors: Okawa Yuji , Namba Hidetoshi , Kuroda Haruo , Yimagawa Masaru , Fujikawa Takashi
Published: March 2014

The atomic arrangement of nitrogen atoms adsorbed on Ni(111) surfaces at room temperature and the structure after annealing were determined by Near Edge X-ray Absorption Fine Structure (NEXAFS) and LEED. Analysis of the experimental data of NEXAFS by full multiple scattering method suggests that, at room temperature, nitrogen atoms randomly occupy three-fold hollow sites of Ni(111) surfaces. By annealing the sample to 670 K, the top layer of the substrate is transformed to a Ni(100)-like atomic arrangement and nitrogen atoms occupy four-fold hollow sites of this reconstructed surface.
SEXAFS Studies of Sulfur Adsorbed on a Nickel Stepped Surface
Authors: Ishii Hideshi , Asakura Kiyotaka , Namba Hidetoshi , Ohta Toshiaki , Kitajima Yoshinori , Kosugi Nobuhiro , Kuroda Haruo
Published: March 2014

The surface structure of (√3×√3)R30° S/Ni(7 9 11) was investigated at room temperature by the SEXAFS method. We found that the mixture of the step 4-fold site and terrace 3-fold hollow site could explain the observed polarization dependence of the EXAFS amplitude successfully. It should be noted that a (√3×√3)R30° LEED pattern can be observed only at low temperature for S adsorption on Ni(111). Present results suggest that the S atoms adsorbed on the step 4-fold site play an important role on stabilizing the S atoms on the terrace site, which yield the (√3×√3)R30° LEED pattern.
Desorption, Dissociation and Orientation of Oxygen Admolecules on a Reconstructed Platinum(110)(1×2) Surface Studied by Thermal Desorption and Near-edge X-ray-Absorption Fine-Structure
Authors: Ohno Yuichi , Matsushima Tatsuo , Tanaka Shin-ichiro , Kamada Masao
Published: March 2014

The desorption, dissociation and orientation of oxygen admolecules on a reconstructed Pt(110)(1×2) were studied by means of TDS combined with isotope tracer, NEXAFS, and angle-resolved TDS. The admolecules below half a monolayer lie on the bottom of the trough, being oriented along it. The molecules adsorbed additionally are lying on declining terraces. The desorption flux of the former species shows a simple cosine distribution, suggesting that the molecule is not localized on the bottom in the desorption event.
Surface EXAFS Study of the Si/AsGa(110) Interface: First Results
Authors: Hasnoui M. L. , Lagarde P. , Delaunay R. , Rossi G. , Flank A.-M.
Published: March 2014

We present here the first results obtained by surface EXAFS on the Si/AsGa(110) interface. Three coverages of 3, 8 and 14 Å of silicon have been deposited on a cleaved surface under ultra-high-vacuum and the spectra for the s and p polarizations have been obtained.
Study by EXAFS and TEM of the Effect of the Reduction-Oxidation Cycles over Pt/Al2O3–K and PtSn/Al2O3–K Catalysts
Authors: Caballero Alfonso , Dexpert Herve , LePeltier Fabienne , Didillon Blaise , Lynch John
Published: March 2014

TEM and X-Ray absorption spectroscopy at the Pt LIII edge have been used to study the effect of several consecutive reduction-oxidation cycles on the state of platinum for two Pt/Al2O3-K and PtSn/Al2O3-K catalysts used industrially for the selective dehydrogenation of high molecular weight paraffins. The results indicate that, whereas the size of the platinum oxide particles in the Pt/Al2O3-K monometallic catalyst increase after the different reduction-oxidation cycles, the presence of tin induces that platinum binds more strongly to the alumina surface, avoiding the sintering of platinum during the different reduction-oxidation cycles.
Ni and W EXAFS of Ni-WS2/C Hydrotreating Catalysts
Authors: Louwers S. P. A. , Prins R.
Published: March 2014

W L
I
I
I
EXAFS of WS2/C and Ni-WS2/C catalysts showed that the WS2/C catalyst contains small WS2 particles of about 7 W atoms, while the Ni-WS2/C catalyst contains larger particles. Ni K EXAFS demonstrated that the Ni atoms were present at the edges of the WS2 particles in a Ni-W-S like structure, like the Ni-Mo-S structure in Ni-MoS2/C catalysts. In the Ni-WS2/C catalysts Ni is, however, coordinated by six sulphur atoms, four at 2.22 Å and two at 2.35 Å from the Ni atom.
Deterioration of the “Ni–W–S” Phase of Hydroprocessing Catalysts during Reaction
Authors: Shimada Hiromichi , Matsubayashi Nobuyuki , Sato Toshio , Yoshimura Yuji , Imamura Motoyasu , Kameoka Takashi , Yanase Hiroshi , Nishijima Akio
Published: March 2014

The structures of fresh and aged Ni–W catalysts supported on Al2O3 have been analyzed by the XAFS techniques. The local structures around Ni and W in the fresh catalyst were found to be basically the same as those around Ni and Mo, respectively, in Ni–Mo catalysts. For aged catalysts, apparent increases in the coordination numbers of S and W around W were observed relative to the fresh catalyst. The local structure around Ni dramatically changed after aging for 950 h. These results suggest that WS2 slabs grow in the lateral direction during the reaction and that Ni atoms are released from the edge sites of the WS2 slabs.
EXAFS Study of Ni–Mo/Al2O3 Hydrodesulfurization Catalysts
Authors: Umeki Takashi , Matsuda Satoshi , Akai Yoshio , Matubayashi Nobuyuki , Nomura Masaharu , Takyu Toshiyuki
Published: March 2014

Ni promoter effect on the structure and the sulfiding state of Mo phase in Ni-Mo/Al2O3 catalysts were studied using Temperature Programmed Sulfiding (TPS) and XAFS. The results for TPS and Mo-K edge EXAFS suggest that Ni addition promotes the sulfiding of Mo phase and the growth of MoS2-like species in the horizontal direction. Ni-K edge XAFS results for sulfided catalysts show that most of Ni atoms may exist as oxidic state.
EXAFS Study of a Germanium Catalyst in PET Polymer
Authors: Nishioji Hiroshi , Hashimoto Hideki , Iida Yutaka , Saisho Hideo
Published: March 2014

Despite of its usefulness in gaining valuable structural information on a variety of catalysts, XAFS has not been previously used to study the catalysts remaining in polymers. In the production of PET (polyethylene terephthalate) bottles, germanium oxide is used as a polymerization catalyst to improve transparency, and the catalyst remains in those products at very low concentration levels of a few tens of ppm. In the present study, the structure of germanium remaining in a PET bottle was determined by use of the EXAFS method. It was found that germanium in the PET, forming a crystalline germanium oxide structure, has a somewhat less ordered structure than germanium oxide.
Electronic Structure and Symmetry of the Itinerant States in High Tc Superconductors
Authors: Bianconi Antonio , Pompa Margherita , Turtu' Simonetta , Pagliuca Silvia , Lagarde Pierre , Flank Anne Marie , Li Chenxi
Published: March 2014

The linearly polarized Cu L3 XANES (X-ray Absorption Near Edge Structure) spectra of several high Tc superconductor single crystals and of their parent insulating compounds have been measured. The spectra have been interpreted in the frame of the full multiple scattering (MS) theory in the real space. Over a range of 40 eV, the polarized Cu L3 XANES spectra have been predicted in term of a one-electron dipole (Δl=+1) transitions, probing the partial density of states of the conduction bands projected on the Cu site with the selected orbital angular momentum l=2 and their projections ml. The oscillator strenght for the dipole allowed transitions Δl=-1 has been found to be a factor 100 weaker than the Cu 2p to 3d transitions. The physical origin of all features in the continuum XANES spectra and the effect of the electron-hole Coulomb interaction in the final states have been identified. The difference spectra between the metal and the insulating phase allows to identify the symmetry of the itinerant 3d9L states induced by doping, that is deduced to be a mixture of Cu 3d holes with ml=0, and 2 orbital angular momentum and oxygen 2p holes on planar oxygen in the molecular orbital combination of local a1 and b1 symmetry. Evidence for the more delocalized character of (3d9
x2-y2
) L(b1) states versus the more localized character of (3d3z2-r2
) L(a1) states has been found.
Multielectron Excitations at the L Absorption Edge of Rare Earths
Authors: Chaboy J. , Garcia J. , Marcelli A. , Tyson T. A.
Published: March 2014

In this work, an x-ray absorption study at the L edges of several rare earth compounds is presented. In both L2 and L3 spectra a multi electron structure is clearly extracted and interpreted as an intra-atomic two-electron transition involving 2p and 4d electrons. In particular this work clearly investigates the presence and characterizes the structures in the EXAFS spectra. The role of multiplets and the cross sections of the allowed double electron transitions are also discussed.
Anomalous Temperature Behavior of Impurities in Lead and Silver Hosts
Authors: Newville Matthew , Stern E. A. , Haskel D. , Shechter H. , Yacoby Y.
Published: March 2014

XAFS and Mössbauer effect measurements were made on impurities that lower the bulk melting temperature, T
m
, of Pb and Ag. In addition XAFS measurements were made on Tl impurities that raise T
m
of Pb. The spectral intensity of the Mössbauer signal in Pb varies as expected from harmonic vibrations of the 1 at.% Sn Mössbauer atoms below a temperature of about 140K. Above this temperature the spectral intensity drops rapidly which is attributed to a localized hopping associated with a high entropy density. In Ag hosts a similar behavior occurs above 900K. The XAFS signal from Hg impurities in Pb, which like Sn lowers T
m
, starts deviating from vibrational behavior above 400K where the apparent coordination number decreases. This is also interpreted as a localized hopping. However, Tl, which raises T
m
, shows the normal vibrational behavior in XAFS measurements in a Pb host. XAFS measurements on Ga impurities in Ag, which also lower T
m
of bulk Ag, show only expected anharmonic behavior up to 900K. All of these results suggest a liquid-like high entropy region within a radius of somewhat more than an atomic spacing around impurities that lower T
m
. These high entropy, or “premelted”, regions could act as nucleation sites for three dimensional melting and should dominate over both grain boundaries and free surfaces in nucleating bulk melting in large single crystals.