bluuebunny/crossref_metadata_2025 huggingface dataset:
Electromechanical Properties of Poly-L-Lactic Acid
Authors: Ochiai Tsutomu , Fukada Eiichi
Published: October 2002

The electromechanical coupling coefficient, the
piezoelectric constant, the elastic compliance constant and the
mechanical quality factor for a poly-L-lactic acid (PLLA) plate
elongated to 4 times the original length were determined by a
self-resonant method. k
14=0.064, d
14=9.82×10-12 C/N,
s
44

E
=9.28×10-10 m2/N and Q

m
=30.3 were obtained at room temperature
for a 0° X-cut square plate. It is noted that elongated PLLA
films have no spontaneous polarization, unlike poled polymers
such as poly(vinylidene fluoride) (PVDF), but still have a large
shear piezoelectric constant.
Second-Harmonic Generation in Achiral Bent-Shaped Liquid Crystals
Authors: Choi Suk-Won , Kinoshita Yoshitaka , Park Byoungchoo , Takezoe Hideo , Niori Teruki , Watanabe Junji
Published: October 2002

Second-harmonic generation (SHG) has been observed as
functions of temperature, electric field and incidence angle in the
liquid crystal phases of the achiral bent-shaped molecules with
octyloxy end chains (P-8-O-PIMB). In the highest temperature B2
phase, the SHG for oblique incidence started to appear at an electric
field when the texture change due to the electric-field-induced
molecular and dipolar reorientations occured. The SHG
interferometry clearly indicated the reversal of polarization on
reversing the applied field in the B2 phase. The other two phases,
B3 and B4, were also SHG active even in the absence of the field,
indicating the spontaneous polar ordering in these phases. It was
found that similar compounds with hexyloxy end chains (P-6-O-PIMB) and octyl end chains (P-8-PIMB) are not SHG active.
Polarity of GaN Single Crystals Prepared with Na Flux
Authors: Yamane Hisanori , Shimada Masahiko , Endo Tadashi , DiSalvo Francis J.
Published: October 2002

The polarity of GaN platelet and prismatic single crystals grown in sodium flux at 750°C
was investigated by X-ray single-crystal diffraction. The smooth (0001) facet of platelet single
crystals corresponded to the N-terminated side. The (0001) facet on which small hillocks were
observed corresponded to the Ga-terminated plane. The c-axis direction from N to Ga atoms
was defined as running from the pedion (flat base) to the pyramid (apex) of the prismatic
crystals.
The Excimer Laser-induced Ripple Structures at the Interfaces of Silicon-dioxide/Silicon Substrates
Authors: Lu Yong Feng , Yu Jian Jun , Choi Wee Kiong
Published: October 2002

Excimer laser-induced surface structures at the interfaces of silicon dioxide/silicon
have been investigated experimentally. It is found that a stable, fine and
homogeneous ripple structure is preferentially generated under a comparatively larger
laser beam. The ripple periodicity seems to have no angular dependence and is
enhanced with the increased laser pulses for the first a few pulses. The initial substrate
temperature also represents an important parameter which can be used to control the
interface ripple structures. The threshold pulse number for the
ripple formation at different laser fluence, or at different oxide thickness is studied
as well. This study will be helpful in understanding the physics of laser-induced ripple
formation, and hence be useful in controlling the ripple structures within the range
required for the laser texturing of the high density magnetic recording media.
Charged Particle Emission and Luminescence upon Bending Fracture of Granite
Authors: Yoshizo Kawaguchi Yoshizo Kawaguchi
Published: October 2002

Charged particle emission and luminescence upon bending
fracture of granite were investigated in a vacuum. In
most cases, sharp peaks of charged particle emission and
luminescence were observed at the very instant of final
fracture, and continued for several seconds. However, it
sometimes happened that the bending fracture needed about
10-20 ms, and a sharp peak of charged particle emission
was also observed at the beginning of the decrease in the
applied load, suggesting that initiation and propagation
of microcrack induced the charged particle emission. In
both cases, luminescence was observed only at the instant
of final fracture. Luminescence spectra were composed of
two bands centered at about 2.1 and 3.0 eV, and each band
showed different decay profiles, suggesting the contribution
of the different defect centers.
Removal of NOxand SO2from Air Excited by Streamer Corona: Experimental Results and Modeling
Authors: Amirov Ravil H. , Chae Jae O. , Dessiaterik Yuriy N. , Filimonova Elena A. , Zhelezniak Mark B.
Published: October 2002

The effect of pulse corona discharge on NOxand SO2concentrations in air has been studied. The initial concentrations and ammonia addition have been shown to influence the removal efficiency. An SO2removal efficiency of 96% and an NO removal efficiency of 70% in pulse corona have been achieved with ammonia addition, for initial SO2and NO concentrations of 480 ppm and 230 ppm, respectively. A numerical model for NO and SO2conversion in homogeneous gas flow has been developed. The spatial nonuniformity of gas parameters associated with the existence of many streamer channels in a discharge chamber is taken into account. A comparison between experiments and modeling shows that SO2removal is mainly determined by OH and O3-. NO conversion is achieved the reactions of O3, OH and N.
Starting Process of Laser-Triggered Vacuum Arc Ion Source
Authors: Jun Hasegawa Jun Hasegawa , Mitsuo Nakajima Mitsuo Nakajima , Kazuhiko Horioka Kazuhiko Horioka
Published: October 2002

A laser-triggering method was applied to a vacuum arc ion source to improve triggering reliability.
A frequency-doubled Nd-YAG laser was focused onto the arc cathode at a laser power density of (4.5–6.1)×108 W/cm2.
Time-resolved observations revealed that a cathode spot was initially formed within the laser focusing area and
the distribution of the cathode spots expanded circularly with time because of the retrograde motion of each cathode spot.
The mean square displacement of the retrograde cathode spot was found to be proportional to the discharge time.
Moreover, arc ignition probability with the laser trigger was measured under various conditions.
It was found that the ignition probability strongly depends on the laser intensity and the gap spacing.
This paper discusses the starting process of the laser-triggered vacuum arc discharge on the basis of the experimental results.
Velocity Fluctuation of Cold Cs Atoms in a Travelling Plane Electromagnetic Wave
Authors: Chang Soo , Jo Jae Heung , Lee Ho Seong
Published: October 2002

We theoretically investigated the transverse and longitudinal velocity fluctuations of
initially cooled Cs atoms below (or close to) the Doppler limit as the atoms were
slowly accelerated in a travelling plane electromagnetic wave. We first derived a
kinetic equation describing the atomic motion in the first order rate equation
approximation and then numerically solved the equation. Increase or decrease in the
longitudinal fluctuation was shown to depend upon the initial atom temperature and
the detuning, while the tranverse fluctuation routinely increased with interaction time.
Tapering the Field Amplitude of a Uniform Gap Permanent Magnet Undulator
Authors: Bhalchandra Gore Bhalchandra Gore , Vivek Asgekar Vivek Asgekar
Published: October 2002

A method to taper the field amplitude in permanent magnet undulators
without changing the undulator gap is presented. It is based on the
deviations in the field patterns of the magnet blocks produced by the
incorrect orientation of the magnetization vector. The appropriate
arrangement of the magnet blocks in the undulator is determined by
solving a set of linear equations obtained using the field values which
characterize the tapered field profile. The versatility of the method
is demonstrated by simulating different profile shapes using the same
set of magnet blocks. It is shown that undulator field profiles of
required shape and size can be obtained by using magnet blocks of proper
specifications. The results of the simulations carried out to study the
effects of the taper size, profile shape and the undulator gap on the
widths of the distributions of the block magnetization components are
presented. As a practical realization of the method a fifteen period
long undulator with linearly decreasing field amplitude is assembled.
The results of the magnetic field measurements of this undulator are
also presented.
Laser Long-Path Absorption Lidar Technique for Measuring Methane Using Gas Correlation Method
Authors: Minato Atsushi , Kobayashi Takao , Sugimoto Nobuo
Published: October 2002

We studied a new laser long-path absorption lidar technique
using a gas correlation method for measuring methane in the
atmosphere. The method employs a broad-band multimode infrared
pulsed laser and a cell containing methane as the correlation
filter. The correlation filter is used to analyze the spectra
of the transmitted and received pulses. We obtained a simple
equation for deriving the density of the target molecule from
an analogy of the differential absorption method. The
measurement method was evaluated by a simulation study to
measure methane in the 3 µm region using a solid-state optical
parametric oscillator. The result shows that atmospheric
methane can be measured by a system using the reflection from
a hard target, and that the methane density derived by a simple
equation has good linearity in the practical density range in
methane measurements. It also indicates that the measurement
is not sensitive to fluctuations in the multimode laser spectrum.
The measurement system is compact and useful for various field
measurements of atmospheric methane.
Ray-Tracing in Gradient Index Tapered Planar Waveguides with Hyperbolic Secant Refractive-Index Profiles: On-Axis and Off-Axis Coupler Devices
Authors: Pérez M. Victoria , Bao Carmen , Gómez-Reino Carlos
Published: October 2002

An analysis of light propagation through tapered hyperbolic secant planar
waveguides is made from geometrical optics. Ray-tracing equations are obtained and
angle and position transformations and numerical aperture conversion are calculated in
order to design typical devices for integrated optics. The results are applied to a special
type of taper function called convergent parabolic profile.
Multimode Polymeric Optical Waveguides with High Thermal Stability Using UV Cured Epoxy Resins
Authors: Enbutsu Koji , Hikita Makoto , Yoshimura Ryoko , Tomaru Satoru , Imamura Saburo
Published: October 2002

We fabricated low loss multimode polymeric optical waveguides with high thermal
stability using UV cured epoxy resins. We also measured the increment in the propagation
loss with a short storage heating test to take account of the soldering process. The minimum
propagation loss of the waveguide at 830 nm was 0.13 dB/cm. There was almost no increment
at 830 nm after heating test at 250°C for one hour.
Highly Precise Alignments Using Moiré Diffraction Methods
Authors: Kawai Shigeru , Torii Yasuhiro
Published: October 2002

Less than 40-nm alignments may be required in future processes for manufacturing 1 Gbit-DRAMs (Dynamic Random Access Memories). Alignment techniques using moiré
between two patterns are considered advantageous techniques, because patterns for moiré can
be easily fabricated in lithography processes. Highly precise alignments using moiré
techniques for mask alignments are proposed. The patterns on masks can be relatively
arranged to standard patterns on a wafer by observing the diffraction beams from the moiré
between the patterns on the masks and a wafer. This technique is called the moiré
diffraction method. The principles of this method, the fundamental experimental results and
the implementation to mask alignments are described.
Efficiency Simulation for Diamond-Turned Diffractive Lenses
Authors: Yamagata Michihiro , Yasuhiro Tanaka Yasuhiro Tanaka , Tomohiko Sasano Tomohiko Sasano
Published: October 2002

Diffraction efficiencies of hybrid diffractive-refractive lenses fabricated by the diamond turning process are discussed.
Since the tip of a diamond tool has a certain nose radius, the relief profiles are rounded by the diamond turning process.
Consequently, fabricated lenses have different diffraction efficiencies from their design.
A computer simulation software based on the scalar diffraction theory was developed to calculate the diffraction efficiency of diamond-turned hybrid lenses.
Hybrid achromatic lenses for optical pickups are simulated and measured.
For a 10 µm nose radius, simulation results showed a diffraction efficiency of 82%.
The difference in diffraction efficiency between simulation results and measurement results was less than 2%.
Dual focus object lenses for compact disk (CD) and digital versatile disk (DVD) compatible pickups were also simulated.
The difference in diffraction efficiency for our developed relief profile was small enough even with a 50 µm process.
Axial Beam Shaping with Nonspherical Microoptics
Authors: Grunwald Rüdiger , Woggon Siegfried , Griebner Uwe , Ehlert Rudi , Reinecke Wolfgang
Published: October 2002

Thin film technologies have been used to fabricate special types of continuous-relief microoptical
arrays with extremely nonspherical phase functions for axial beam shaping. Microlenses with
Gaussian and double-parabolic profiles are found to generate extended or axially oscillating foci and
have also been found to be much less sensitive to the axial position and tilt in comparison with
parabolic lenses. The optical properties have been determined in improved experiments. The
focusing behavior of the small bifocal microlenses with short focal distances has been investigated
with a scanning near-field optical microscope (SNOM). The results of excimer laser drilling of
holes in glass using microlenses with two axially separated focal zones are presented. Applications
for mode-selection in micro-lasers and axial scanning and switching are proposed.
Sidelobe Suppression of Vertical Coupler Filter with an X-Crossing Configuration
Authors: Tak Chu Sai , E. Little Wugan Pan , Yasuo Kokubun Yasuo Kokubun
Published: October 2002

An antiresonant reflecting optical waveguide (ARROW) type vertical
coupler filter exhibiting low sidelobe charateristics is demonstrated.
The sidelobe level of the filter has been suppressed by using an X-crossing
arrangement to provide strength apodization along the device.
The main sidelobe of the fabricated filter is measured to be less than
-17 dB with the central wavelength in the 1.55 µm region.
An analysis procedure which combines the coupled mode theory with
the finite difference mode solver is also
presented to efficiently calculate the vertical coupler filter response.
Micromachined Photodiode Submount with Integrated Mirror for Efficient Out-of-Plane Coupling to Planar Polymeric Waveguide Circuits
Authors: van der Linden Johan E. , De Dobbelaere Peter M. , Van Daele Peter P. , Diemeer Mart B.
Published: October 2002

We report on a hybrid coupling concept which allows high-density integration of top illuminated photodetector
arrays with planar polymeric waveguide circuits by means of a micromachined submount with an integrated mirror.
The etching of a complementary alignment structure in the polymeric layer stack allows passive assembly. The
fabrication process of the submount structure is described, focusing on the optimization of the mirroring facet
surface quality in order to reduce the effect of topographic scattering. A prototype 8-channel detector module
integrated with a straight polymeric waveguide array exhibited an average coupling efficiency of -6.1 dB and a
cross-talk value of -21.3 dB between adjacent channels at 1300 nm.
Characteristics of a Guided-Wave Displacement Sensor Based on Wavefront Detection
Authors: Doi Masaaki , Iwasaki Yutaka , Shionoya Takashi , Okamoto Kazuya
Published: October 2002

The characteristics of a guided-wave displacement sensor based on the
wavefront detection are obtained. The displacement is measured by detecting
the wavefront gradient of the light reflected from the measured object. The
wavefront gradient is determined using the mode interference of the even and
odd modes in the double-mode waveguide which is fabricated of silica glass on a
Si substrate. The measuring range is 3 µm and the resolution is determined to
be less than 1 nm. The object tilting dependence and the stability of the sensor
are also measured. Furthermore, sample surfaces are observed and very fine
images are obtained using this sensor. The optical system is very simple and
the sensor is very compact, hence it will be useful as a built-in component for
various kinds of industrial equipment.
Local Electronic Properties in the Presence of Internal and External Magnetic Fields Studied by Variable-Temperature Scanning Tunneling Spectroscopy
Authors: Wiesendanger Roland , Bode Matthias , Dombrowski Ralph , Getzlaff Mathias , Morgenstern Markus , Wittneven Christian
Published: October 2002

We have developed a new low-temperature ultrahigh vacuum scanning tunneling microscope
(UHV-STM) setup combined with a solenoid and a split-pair magnet. The STM can be operated
in the 10-11 mbar range, down to 7 K and in a rotatable magnetic field of up to 7 T perpendicular
and 2 T parallel to the sample surface.
This LT-UHV-STM setup was applied to study the Landau level quantization in n-type
InAs(110). In addition to the observation of the Landau level splitting of the conduction
band we were able to determine the energy dependence of the effective electron mass
due to the nonparabolicity of the conduction band. Furthermore, we have studied the
scattering of electron waves at dopant atoms located several nanometers (1–20 nm) below
the surface. In a second study we have applied variable-temperature UHV-STM to investigate
the temperature-dependent exchange splitting of a d

z
2
-like surface state of Gd(0001) thin films.
The experimental results indicate that the high spatial localization of the surface state helps to
maintain a local exchange splitting even above the Curie temperature but does not result in an
enhanced surface Curie temperature. Finally, we have demonstrated spin-polarized vacuum
tunneling from a ferromagnetically-coated tip into the exchange-split surface state of Gd(0001).
Atomic Hydrogen Interaction with the Si(100)4×3-In Surface Studied by Scanning Tunneling Microscopy
Authors: Ryu Jeong Tak , Kubo Osamu , Tani Hitoshi , Katayama Mitsuhiro , Saranin Alexander A. , Zotov Andrey V. , Oura Kenjiro
Published: October 2002

Using scanning tunneling microscopy and low energy electron diffraction techniques,
we have investigated the structural rearrangement of Si(100)4×3-In surface induced by
room temperature interaction with atomic hydrogen. The disintegration of the 4×3-In
layer into three-dimensional In islands is substantiated by direct evidence. It has been
found that In-denuded regions exhibit the stripes of 4a (a=3.84 Å) periodicity,
indicating that the Si substrate in the Si(100)4×3-In phase has a 4×1 reconstruction. The
mode of atomic hydrogen interaction with Si(100)4×3-In surface phase has been
determined. By comparing the present results with the known data of other
submonolayer metal/silicon systems, the relationship between the adsorbate bonding
and the mode of surface reaction with atomic hydrogen is established.
Scanning Tunneling Microscopy Study on Self-Formation Process of Quantum Dot Structures by the Growth of GaP/InP Short-Period Superlattices on GaAs (311)A Substrate
Authors: Noh Joo-Hyong , Asahi Hajime , Kim Seong-Jin , Gonda Shun-ichi
Published: October 2002

Self-formation process of quantum dot (QD) structures in (GaP)1.5 (InP)1.88 short-period superlattices (SLs) grown on GaAs (311)A substrates by gas source MBE (molecular beam epitaxy) are studied by scanning tunneling microscopy (STM). STM images reveal high-density (1011–1012 cm-2) QD structures periodically aligned along the [233] and [011] directions. STM observations of the self-formed structures as a function of SL cycle number show that almost complete QD structures are formed only after the growth of 1 cycle of SL (1.5 monolayer GaP and 1.88 monolayer InP), although the periodic structures elongated only along the [011] direction are formed even after the growth of 0.5 cycle of SL (1.5 monolayer GaP). In the d
I/d
V vs. V measurement, the voltage width (ΔV) for the d
I/d
V=0 varies periodically along the lateral direction on the sample surface, and the amplitude of this periodic variation increases with the SL cycle number and saturates at 2 SL cycles.
Surface Superstructure of Carbon Nanotubes on Highly Oriented Pyrolytic Graphite Annealed at Elevated Temperatures
Authors: An Bai , Fukuyama Seiji , Yokogawa Kiyoshi , Yoshimura Masamichi
Published: October 2002

Carbon nanotubes deposited on highly oriented pyrolytic graphite (HOPG) are
annealed in ultra high vacuum. The effect of annealing temperature on the surface
morphology of the carbon nanotubes on HOPG is examined by scanning tunneling
microscopy. The ring-like surface superstructure of (√ 3×√ 3)R30° of graphite is
found on the carbon nanotubes annealed above 1593 K. The tips of the carbon
nanotubes are destroyed and the stacking misarrangement between the upper and the
lower walls of the tube join with HOPG resulting in the superstructure.
In situ Scanning Tunneling Microscopy Nanotip Fabrication with Field-Enhanced Surface Diffusion, Thermal Evaporation and Field Emission
Authors: Huang Dehuan , Yamaguchi Fumiko , Yamamoto Yoshihisa
Published: October 2002

A method of fabricating a nanotip in situ in a scanning tunneling
microscope by field-enhanced surface diffusion, thermal evaporation and field
emission is described. We also discuss the physical mechanisms involved in
the processes and the difference between this method in the scanning tunneling
microscope and other methods in field ion microscopy and field emission
microscopy.
Scanning Tunneling Microscope Observation and Manipulation of DNA and DNA-Related Molecules in Aqueous Condition
Authors: Tano Tomoko , Tomyo Masatoshi , Tabata Hitoshi , Kawai Tomoji
Published: October 2002

We have studied the structure of adsorbed DNA and DNA-related molecules, such as
adenosine, adenosine triphosphate disodium (ATP-2Na) and short single-stranded DNA
oligomer (3 to 20 base pairs) adsorbed on Au(111) substrate by scanning tunneling
microscopy (STM). Adenosine and ATP are spontaneously adsorbed on the Au substrate in
1.0×10-4 mol/l solution, and are imaged clearly as densely packed clusters. The adenosine
clusters have been observed as hydrogen-bonded dimers which tend to dissociate with a
change in the pH towards the alkaline condition. The ATP cluster has a spherical shape
with a diameter of 150 Å. In the case of DNA oligomers, clear STM images can be
observed after pre-rinse treatment or electrochemical treatment. The images of all the
DNA oligomers are round with a diameter of 30 to 50 Å. This reveals the aggregated
structures of DNA at the Au-solution interface. The manipulation of these DNA oligomers
can be achieved by the lateral pushing of the microscope tip.
Scanning Tunneling Microscopy on Ordered Self-Assemblies of Cyclodextrin Inclusion Complexes Formed by Substrate-Induced Two-Dimensional Crystal Growth
Authors: Yasuda Satoshi , Miyake Koji , Goto Yasuyuki , Ishida Masahiko , Hata Kenji , Fujita Mitsutaka , Yoshida Mitsuho , Sumaoka Jun , Komiyama Makoto , Shigekawa Hidemi
Published: October 2002

Cyclodextrin (CyD) inclusion complexes with water and methanol, both of which had been known to form the cage-type crystal structure in the three dimensional crystal growth mode, were observed to form new self-assembled structures on highly oriented pyrolytic graphite (HOPG) and MoS2 surfaces. By removing the surface CyD molecular layers using the atom manipulation technique of scanning tunneling microscopy (STM), ordered molecular stacking of the inner layers was observed. The surface of the observed CyD layers was markedly flat, indicating a stronger interaction between CyDs in each layer compared to that between the adjacent CyD layers, which is possibly related to the two-dimensional crystal growth mode induced by the anisotropic hydrogen bonding interaction between CyDs. On MoS2, CyD has threefold symmetric lattice matching commensurate with the structure of S atoms, which is considered to affect the ordering of the self-assemblies. In fact, numerous defects are observed in the surface layer.
Simulation of Long-Range Contrast Modulation in Scanning Tunneling Microscope Image of Perylene-3,4,9,10-Tetracarboxylic-Dianhydride Monolayer on Graphite
Authors: Ogawa Tetsuya , Irie Satoshi , Isoda Seiji , Kobayashi Takashi , Whangbo Myung-Hwan
Published: October 2002

In order to simulate the scanning tunneling microscope (STM) image of
perylene-3,4,9,10-tetracarboxylic-dianhydride (PTCDA) on graphite, we calculated the
partial electron density, which is proportional to the tunneling current, by the extended
Hückel tight binding method. The typical STM images of PTCDA have two characteristic
features: (i) long-range contrast modulation caused by point-on-line coincidence and (ii)
contrast difference due to molecular orientation with respect to the graphite substrate.
Using the present simulation, these features can be reproduced from the expected
geometrical relationship between PTCDA and graphite.
Characterization of Highly Efficient CdTe Thin Film Solar Cells by Low-Temperature Photoluminescence
Authors: Okamoto Tamotsu , Matsuzaki Yuichi , Amin Nowshad , Yamada Akira , Konagai Makoto
Published: October 2002

Highly efficient CdTe thin film solar cells prepared by close-spaced sublimation (CSS) method
with a glass/ITO/CdS/CdTe/Cu-doped carbon/Ag structure were characterized by low-temperature
photoluminescence (PL) measurement. A broad 1.42 eV band probably due to VCd–Cl defect
complexes appeared as a result of CdCl2 treatment. CdS/CdTe junction PL revealed that a
CdS
x
Te1-x
mixed crystal layer was formed at the CdS/CdTe interface region during the deposition of
CdTe by CSS and that CdCl2 treatment promoted the formation of the mixed crystal layer.
Furthermore, in the PL spectra of the heat-treated CdTe after screen printing of the Cu-doped carbon
electrode, a neutral-acceptor bound exciton (ACu
0, X) line at 1.590 eV was observed, suggesting that
Cu atoms were incorporated into CdTe as effective acceptors after the heat treatment.
Conduction-Band Discontinuity of InAsP/InP Heterojunction
Authors: Anan Takayoshi , Nishi Kenichi , Tomita Akihisa , Tokutome Keiichi , Sugou Shigeo
Published: October 2002

The band line-up of InAsP/InP heterojunctions was investigated. The conduction-band
discontinuity ratio Q
c of strained InAsP alloys was determined by fitting the well
thickness dependence of transition energies in InAsP quantum wells. This method
does not require precise values of deformation potentials of InAsP, allowing more
reliable determination of the band offset. The obtained Q
c value was 0.35, which is
relatively small compared to previous reports. This value of the band offset is
consistent with the predictions from the semi-empirical linear combination of atomic
orbitals (LCAO) model.
Ferromagnetic Resonance in Metal Particulate Tapes
Authors: Kohmoto Osamu
Published: October 2002

The magnetic anisotropy field (H
a) of metal acicular particles in audio tapes was studied using ferromagnetic resonance (FMR).
The H
a value of 5.28 kOe was obtained assuming acicular particles
having a saturation magnetization of M=1.70 kG and a gyromagnetic
factor of γ/2π=2.926 GHz/kOe of pure Fe. From H
a=5.28 kOe, the
axial ratio of 2.1 is reduced; the value is smaller than the
expected value (5–10) due to the shape of acicular particles.
Blue Electroluminescence in SrSO4:Ce-Based Thin-Films
Authors: Morishita Takashi , Ichii Akira , Matsui Masahiro , Tonomura Shoichiro , Konishi Tokuzo
Published: October 2002

A blue electroluminescence (EL) device was fabricated using SrSO4:Ce-based phosphor layers
deposited by rf sputtering in Ar–H2S atmosphere. Peak emission wavelength was observed at 420 nm
corresponding to the energy transition from the T2g(5d) level to the F5/2(4f) level of Ce ions.
This wavelength is shorter than any previously reported, which suggests that the energy state of
the excited 5d electrons is sensitive to the crystal field surrounding Ce ions. A high-resolution
two-crystal X-ray fluorescence spectrometer (HRXRF) was used to examine the composition of the
SrSO4-based phosphor layers and chemical state of Ce ions in them. The chemical state of Ce ions
was primarily 3+ in the blue-green emitting phosphor layers, which were mainly composed of
SrS. An increase in SrSO4 concentration in the phosphor layers leads to a change in the chemical
state of Ce ions, resulting in a blue shift in EL emission. A constant high luminance of 5 cd/m2 was
obtained under 5 KHz sinusoidal driving. The transferred charge density of the SrSO4:Ce-based EL
device was found out to be fairly low compared to the conventional SrS:Ce EL device.
Study of the Relationship between Space Charge Field and Electrical Treeing in Low Density Polyethylene under a Needle-Plane Electrode System
Authors: Fukuzawa Masahiro , Iwamoto Mitsumasa
Published: October 2002

The inception voltage of electrical treeing and the length of the electrical treeing path in low density polyethylene (LDPE) were examined using a needle-plane electrode system, by applying an AC voltage with a frequency of 10–120 Hz. In order to obtain the relationship between the length of the electrical treeing path and the space charge distribution in LDPE, thermally stimulated current measurement was employed using a similar needle-needle electrode system. It was revealed that the length of the path generated due to the electrical treeing was approximately the same as the depth of electrons injected from the needle electrode.
Morphology of Polypropylene and Tree Initiation
Authors: Xu Jianfei , Yan Ping , Yoshimura Noboru , Nakagawa Zenbe-e
Published: October 2002

The morphological aspect of a polypropylene (PP) sample is investigated using an X-ray diffractometer,
differential scanning calorimetry (DSC) and an infrared (IR) spectrophotometer. It is found that the samples
with spherulite used in this study are composed mainly of the γ-form and a small amount of the α-form,
and that the sample without spherulite is composed of a pseudohexagonal phase. The effect of morphology,
oxygen and ultraviolet ray (UV) irradiation on tree initiation, and the influence of morphology on space
charge are also studied. It is found that space charge storage becomes more difficult and that tree initiation
voltage becomes higher with an increase of crystallinity and crystallite size of PP. In the presence of oxygen,
tree initiation is attributed to both the accumulation of space charges and the reaction of free radicals with
oxygen, while tree initiation is only attributed to the accumulation of space charge in the absence of oxygen.
Crystal Direction of CdS Thin Film Produced by Laser Ablation
Authors: Sakai Hisashi , Tamaru Takeyoshi , Sumomogi Tsunetaka , Ezumi Hiromichi , Ullrich Bruno
Published: October 2002

The crystal direction of CdS thin films produced by the laser ablation was
measured using X-ray diffractometer (XRD). The results reveal that the direction
of the CdS crystal depends considerably on the substrate temperature and laser
energy density. The c-axis of the CdS crystal changed from perpendicular to
parallel with the surface as the laser energy density increased. The parallality
of c-axis may be due to the clusters included in the laser plume. On the other
hand, the c-axis changed from parallel to perpendicular as the substrate
temperature increased. This phenomenon is considered to be that the clusters
on the substrate melting and re-crystallizing at the film surface due to the
high temperature prevailing during laser ablation.
High-Speed Camera Study of the Surface Wave Discharge Propagation in Xenon
Authors: Kudela Jozef , Odrobina Igor , Kando Masashi
Published: October 2002

The formation and advance of filamentary and diffusive microwave surface wave plasma
columns in xenon are studied by means of a high-speed camera. The framing photographs
show that the ionization front of the filamentary surface wave discharge exhibits a corona-leader-like behavior. The streak photographs show that during the ionization front
propagation, the discharges in both forms are sustained by a standing surface wave. At lower
pressures, the streak photographs reveal the existence of a localized highly-luminous
ionization front, which could indicate the presence of resonance absorption. The ionization
front propagation velocity of both filamentary and diffusive plasma columns is measured as a
function of microwave power.
DeNO x Characteristics of Tungsten and Copper Wire Electrodes in Wire-to-Plane Configuration under Conditions of DC Positive Streamer Corona
Authors: Gasparik Robert , Gasparikova Maria , Yamabe Chobei , Satoh Saburoh , Ihara Satoshi
Published: October 2002

Removal rates of NO
x
have been examined for two materials, W and Cu, used
as a high-voltage electrode in a wire-to-plane configuration, under conditions of a DC
positive streamer or positive corona discharge. Input gas composition and series
resistance were varied, and the highest removal rate was obtained for water including
gas with a W electrode and low resistance value. Discharge characteristics with both the
wires are described.
Synchrotron Radiation Topographic Camera for Continuous Observation
Authors: Mizuno Kaoru , Nagai Shin-ya , Tamiya Atsuhiro , Hashimoto Eiji , Ito Kazuyoshi , Kino Takao
Published: October 2002

An X-ray topographic camera in the high-speed X-ray topographic
station (BL-15B) at the Photon Factory, High Energy Accelerator Research
Organization was improved for continuous observation with nuclear plates.
Using this camera, several topographs were taken during heating process of
nearly-perfect aluminum single crystals. As a result, an obscure topograph,
in which not only defect images but also fringe are unclear, was taken in
spite of very short exposure time (2.0 s) just prior to the appearance of
interstitial-type dislocation loops grown as vacancy sources.
Orthogonal Relations for Quantization of Evanescent Electromagnetic Wave in Parallel Plate Waveguide Partly Filled with Dispersive Dielectrics
Authors: Jingbo Li Jingbo Li , Masahiro Agu Masahiro Agu
Published: October 2002

By considering a typical one-dimensional evanescent wave given as a cut-off mode in a parallel plate waveguide, we show a normalization procedure for the quantization of the evanescent wave. The waveguide is assumed to be partly filled with lossless dispersive dielectric medium. New orthogonal relations between the wave modes with arbitrary propagation constants in the waveguide are derived, and normalized wave amplitude is introduced for field quantization. The normalization depends on the dispersive property of the dielectric medium in the waveguide. The wave energy density in the waveguide including that of incident, reflected and evanescent waves is shown to be given by the sum of the energies of independent harmonic oscillators with different frequencies.
Semi-Monochromatic Plasma Flash Radiography and Its Application to Biomedical Imaging Simulation
Authors: Takahashi Kei , Sato Eiichi , Sagae Michiaki , Tsukahara Yasuo
Published: October 2002

A high-intensity plasma flash X-ray generator having a radiation tube
with a rod-shaped target and its application to biomedical imaging
simulations are described. Plasma flash radiography was performed
with charged voltages of 40, 50, and 60 kV, and with filter of the same
material as the target. In the present work, molybdenum target was
employed. With filter of the half value layer in thickness for each target,
nearly monochromatic radiography with only K-characteristic X-ray
spectra could be achieved. Next, with real X-ray spectra data acquired
from the present generator, we performed a computer-aided biomedical
imaging simulation using the program SPECTRA. It was developed as
an assisting tool for our fundamental research on optimum control of
flash X-ray spectra. Qualitatively, the simulated biomedical phantom
images agreed with those from the Computed Radiography.
Low-Power Microwave Electron Source for Ion Engine Neutralizer
Authors: Ikkoh Funaki Ikkoh Funaki , Shin Satori Shin Satori , Hitoshi Kuninaka Hitoshi Kuninaka
Published: October 2002

Operation of an ion engine in space requires an electron source to maintain the spacecraft's electrical neutrality. To neutralize exhausted ions, a low-power, compact microwave electron source was developed. An 18-mm-diameter noncavity-type discharge chamber consisting of an L-shaped antenna and a magnetic circuit was developed, and electron emission current of 100 mA was obtained at the power level of 10 W, maintaining the mass flow rate of xenon at 0.5 sccm.
Strain in GaP Films Heteroepitaxially Grown on Si by Metalorganic Chemical Vapor Deposition
Authors: Kazuhiro Nakamura Kazuhiro Nakamura , Takashi Fuyuki Takashi Fuyuki , Hiroyuki Matsunami Hiroyuki Matsunami
Published: October 2002

The residual stress and strain in GaP layers have been studied
using X-ray diffraction and Raman scattering techniques.
Samples used in this study were GaP films grown on Si substrates
by atmospheric-pressure metalorganic
chemical vapor deposition (MOCVD),
using trimethylgallium (TMGa) and tertiarybutylphosphine (TBP)
as source gases.
Lattice constants of the epitaxial layer were obtained
from the results of X-ray (004) and (115) diffractions.
The lattice constant parallel to the growth surface (a
∥)
was longer than the one perpendicular to it (a
⊥).
The GaP epilayer was two-dimensionally strained in the growth plane.
This is explained by the difference in thermal expansion coefficients.
The degree of strain was also verified
by the results of Raman scattering measurements.
Characterisation of Microcrystalline GaN Grown on Quartz and on Sapphire by Laser and Microwave Plasma Enhanced Metalorganic Chemical Vapour Deposition
Authors: Paterson Melissa J. , Goldys E. M. , Zuo H. Y. , Tansley T. L.
Published: October 2002

We present a comparative study of GaN grown on quartz and on sapphire by laser assisted metalorganic chemical vapour deposition. Films were characterised by X-ray diffraction, Raman spectroscopy and optical transmission. Films grown on both substrates are polycrystalline, with the dominant orientation of (0002) wurtzite or (111) cubic for growth temperatures 550°C and lower. In films grown at 625°C, both on quartz and on sapphire the crystallites show a variety of orientations, all attributed exclusively to wurtzite phase. Films grown at the same temperature are characterised by similar value of the Urbach parameter for both substrates. The Raman spectra in all examined films are alike, and characteristic for a disordered cubic GaN.
Instability of SiO2 Film Caused by Fluorine and Chlorine Inclusion
Authors: Nakanishi Toshiro , Kawamoto Tomokazu , Takasaki Kanetake
Published: October 2002

We studied how the interaction between fluorine and chlorine in SiO2 influences
oxide thickness change and metal oxide semiconductor (MOS) reliability. Anhydrous HF
treatment on amorphous Si (a-Si) introduces a large quantity of fluorine into the gate
oxide compared to HF solution treatment. When the oxide is formed in an HCl
atmosphere, it contains a large quantity of chlorine. If the fluorine atoms diffuse into the
chlorine-rich oxide, Si–Cl bonds are easily replaced by Si–F bonds and the equivalent
thickness increases. This tendency is further enhanced as the oxide becomes thinner. Both
fluorine and chlorine, introduced in excess during the fabrication process, degrade MOS
reliability because Si–F and Si–Cl bonds are weaker than Si–O bonds.
Dependence of Jc on the Composition of Superconductor Films of the Bi System
Authors: Itoh Takanori , Fueki Kazuo , Koyama Tadashi
Published: October 2002

In order to elucidate the effect of metal composition on the critical
current density, J
c of Bi system, the measurement of J
c was carried out on
highly oriented films of Bi2212 with a varied strontium content and of
Bi2Sr2(Ca1-x
Y
x
)Cu2O
y
(BSCYCO) with a varied yttrium content grown on
an MgO single crystal substrate by the spin coating-pyrolysis method. All
the samples showed a considerable decrease in J
c with temperature, probably
due to flux creep. J
c was also found to be much more sensitive to the
film composition than to T
c. The highest value of J
c, 1.4×105 A/cm2,
was observed for Bi2.1Sr
x
CaCu2O
y
with x=1.85 at 4.2 K. The dependence
of J
c on the film composition is discussed in reference to the peculiar
species of excess oxygen and cation vacancies.
Enhanced AC Josephson Effect in YBa2Cu3O7-δ Junctions Driven by Two RF Sources
Authors: Koster Cornelis , Chen Jian , Myoren Hiroaki , Nakajima Kensuke , Yamashita Tsutomu , Takada Akio
Published: October 2002

Enhanced AC Josephson effect for YBa2Cu3O7-δ grain boundary Josephson junctions
driven by two rf sources has been demonstrated. Maximum heights of the first Shapiro
step have been obtained and are in good agreement with simulations based on the
resistively shunted junction (RSJ) model.
Formation of c-Axis Oriented YBa2Cu3O7-y Thin Film on Amorphous Substrates with Al(111) Buffer Layer
Authors: Shigeki Hontsu Shigeki Hontsu , Masaya Nakamori Masaya Nakamori , Hitoshi Tabata Hitoshi Tabata , Akira Fujimaki Akira Fujimaki , Junya Ishii Junya Ishii , Tomoji Kawai Tomoji Kawai
Published: October 2002

C-axis-oriented YBa2Cu3O7-y
(YBCO) films have been formed on (111)-oriented Al films using the pulsed-laser deposition method. The (111)-oriented Al films, which are grown at room temperature, are effective for the formation of a crystallized YBCO film on an amorphous substrate. Before YBCO film formation, the Al surface was oxidized in (O2+8% O3) gas atmosphere to create an AlOx layer on the top surface of the Al film. This AlOx plays the role of a buffer and seed layer which has a periodic potential of atomic order corresponding to the Al(111) plane. The optimal substrate temperature for YBCO deposition was 590° C. The T
c(onset) and T
c(zero) of the YBCO film formed on Al/glass were 90 K and 75 K, respectively.
Electron Spin Resonance and Dilatometric Studies of Ancient Ceramics Applied to the Determination of Firing Temperature
Authors: Bensimon Yves , Deroide Bruno , Clavel Sandrine , Zanchetta Jean-Victor
Published: October 2002

Electron spin resonance (ESR) and dilatometric studies have been performed on clay
fired to various temperatures. ESR spectra are very sensitive to the heat treatment and the
variations of spectroscopic parameters are discussed as functions of the firing temperatures.
The study shows that these ESR parameters can be used for a quantitative determination of
the firing temperature. In the dilatometric analysis, the change of the length as well as the
parameters related to the quartz transition, are sensitive to the heat treatment. The most
significant parameters are selected for this study. The dilatometric determination of the firing
temperature is in good agreement with the ESR results. After a control experiment performed
by both methods on a known clay sample, we finally study an archaeological sample as an
example. Its firing temperature was determined with satisfying accuracy.
Linear Polarizers Based on Polymer Blends: Oriented Blends of Poly(Ethylene-2,6-Naphthalenedicarboxylate) and a Poly(Styrene/Methylmethacrylate) Copolymer
Authors: Jagt Henri , Dirix Yvo , Hikmet Rifat , Bastiaansen Cees
Published: October 2002

The optical properties of linear polarizers based on blends of poly(ethylene-2,6-naphthalenedicarboxylate)
and a poly(styrene/methylmethacrylate) copolymer are
presented. In the oriented blends, the refractive index of the dispersed phase is
matched with the ordinary refractive index of the birefringent continuous phase while,
a large refractive index mismatch is simultaneously generated in the perpendicular
direction. The films are therefore transparent or opaque depending on the polarization
direction of the incident light and act as a linear polarizer. In the non transparent state,
the incident light is mainly scattered in the backward direction (±80%), which
potentially enhances the yield of transmitted polarized light if the backscattered light
is recycled in a suitable device. This latter feature is useful, for instance, in display
applications where a high brightness or energy efficiency is desired.
Structural, Optical, and Field Emission Properties of Hydrogenated Amorphous Carbon Films Grown by Helical Resonator Plasma Enhanced Chemical Vapor Deposition
Authors: Shim Jae Yeob , Chi Eung Joon , Baik Hong Koo , Lee Sung Man
Published: October 2002

Hydrogenated amorphous carbon films have been prepared by helical resonator plasma enhanced chemical vapor deposition using CH4 and H2 mixtures. Films with various physical properties were obtained from different deposition conditions. The structural and optical properties of hydrogenated amorphous carbon (a-C:H) films were more sensitive to the substrate bias than the substrate temperature. This reflects that the energetic ion bombardment modified the films more effectively than the thermal energy. The a-C:H films deposited with no bias applied show characteristics of polymeric films with a large content of C–H bond while the a-C:H films deposited as a function of the substrate temperature at a bias of 40 W show characteristics ranging from diamond-like carbon (DLC) to graphitic nature with a significantly reduced C–H bond. From elastic recoil detection analysis, the hydrogen content in the films also significantly reduced with an increase of substrate temperature at a bias of 40 W. The field emission from bare Si emitters and a-C:H coated Si emitters has been examined in an ultrahigh vacuum chamber. The field emission characteristic of the a-C:H coated Si emitters is better than that of the bare Si emitters. For the a-C:H coated Si emitters, the emission current of the a-C:H coated (at 150°C/40 W) Si emitters is higher than the that of the a-C:H coated (at 260°C/40 W) Si emitters. This difference in field emission characteristic is attributed to the structural and optical properties as well as hydrogen content.
Efficient Intermolecular Energy Transfer between Polysilanes Revealed by Time-Resolved Photoluminescence
Authors: Satoshi Aihara Satoshi Aihara , Norihiko Kamata Norihiko Kamata , Wakana Ishizaka Wakana Ishizaka , Masato Umeda Masato Umeda , Akira Nishibori Akira Nishibori , Daiyoh Terunuma Daiyoh Terunuma , Koji Yamada Koji Yamada
Published: October 2002

Conventional studies on polysilanes have dealt with molecular structures
on an individual basis and only a few studies have been conducted so far on
the intermolecular interaction between different molecules.
In order to investigate the intermolecular
energy transfer process in detail, time-resolved photoluminescence
spectroscopy was carried out against polydihexylsilane
(PDHS), polydiphenylsilane (PDPS) and their mixture in powder form.
Both the intensity
and the lifetime of PDHS emission decreased, while those of PDPS emission
increased in the mixed samples. Their mixing-ratio dependence revealed
that the resonant energy transfer process from PDHS to PDPS
due to multi polar interaction played an important role in
light emission characteristics, thus revealing the possibility of their
molecular design as interacting pairs and their functional applications.
Hydrogenation and Annealing Effects on GaN Epilayers Grown on Sapphire Substrates
Authors: Kang T. W. , Park S. H. , Cho H. D. , Kwak M. Y. , Eom G. S. , Kim T. W.
Published: October 2002

Photoluminescence (PL) measurements have been carried out to investigate the
hydrogenation and annealing effects of unintentionally doped n-type GaN epitaxial layers
grown on sapphire substrates by plasma-assisted molecular beam epitaxy. When the
as-grown GaN/sapphire heterostructure is annealed at 800°C, a new peak corresponding
to the neutral donor-bound excitons appears. After hydrogenation, the yellow peak
appeared for the as-grown GaN/sapphire heterostructure annealed at 800°C disappears.
When the hydrogenated GaN/sapphire heterostructure is annealed at 950°C, three peaks
appears. These results indicate that the crystallinity of the unintentionally doped n-type
GaN epilayers grown on sapphire substrates is improved by hydrogenation and annealing.