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Conventional selected area diffraction patterns as obtained in the TEM present difficulties for identification of materials such as asbestifonn minerals, although diffraction data is considered to be one of the preferred methods for making this identification. The preferred orientation of the fibers in each field of measurement, and the spotty patterns that are obtained, do not readily lend themselves to measurement of the integrated intensity values for each dspacing, and even the d-spacings may be hard to determine precisely because the true center location for the broken rings requires estimation. To overcome these problems, we have implemented an automatic method for diffraction pattern measurement. It automatically locates the center of patterns with high precision, measures the radius of each ring of spots in the pattern, and integrates the density of spots in that ring.
Relativistic electron beam transport through a high-density, magnetized plasma is studied numerically and theoretically. An electron beam injected into a cold plasma excites Weibel and two-stream instabilities that heat the beam and saturate. In the absence of an applied magnetic field, the heated beam continues to propagate. However, when a magnetic field of particular strength is applied along the direction of beam propagation, a secondary instability of off-angle whistler modes is excited. These modes then couple nonlinearly creating a large amplitude parallel-propagating whistler that stops the beam. Here, we will show these phenomena in detail and explain the mechanism of whistler mediated beam stagnation.
We report estimates for the extragalactic background light (EBL) in the K band (2.2 μm), obtained by the integration of galaxy counts down to K=25 mag in the Subaru Deep Field (SDF, 2′ x 2′). We have obtained deep galaxy count data by using the 8.2m Subaru telescope, with a total integration time of 10 hours and an average seeing of about 0.4 arcsec. The 5-sigma limiting magnitude is K=23.5, and 350 objects are detected brighter than this magnitude. There has been a significant discrepancy between previous K-count observations, probably because of the systematic uncertainties in the completeness correction. To overcome this problem, we have paid special attention to selection effects and completeness corrections, with realistic theoretical galaxy models taken into account consistently. The faint-end slope is significantly flatter than some earlier observations of K counts, and our results suggest that the bulk of the extragalactic light in this band has been resolved as discrete sources. We estimate the value of the EBL flux obtained from the integration of our counts as 9.8 ± 1.0 nWm−2 sr−1.
The crystallinity of a GaN epitaxial layer on a sapphire substrate after the mechanical ding process was estimated by transmission electron microscopy (TEM) and Raman spectroscopic analysis. TEM observation results showed that, the screw dislocations as a threading dislocation were induced by the mechanical dicing process in the limited area up to approximately 1.2 μm from the dicing-line. On the other hand, the crystal strains were up to approximately 7 μm from the dicing-line edge measured by the Raman spectroscopic analysis. The distance difference between the area of the screw dislocations and of the residual strain is caused by the stress relaxation.
It is difficult to get a real scale image of the solar system through lecture. A scale model is a classical and one of good solutions (e.g. Handa et al.2003, Handa et al.2008). Through this model, people living in or visiting to the city can physically understand the scale of the solar system. This scale gives 1 cm for Earth's diameter and 115 m for 1 AU. However, some gadget is required to make it attractive for public citizens.
By using electric-field-induced second-harmonic generation (EFISHG) measurement, we analyzed photovoltaic effect of two-layer solar cells (indium zinc oxide/pentacene/C60/Al). Results evidently showed that negative and excessive charges Qs accumulated at the two-layer interface under illumination, e.g., Qs =-1.7×10-9 C/cm2 at 0.05 mW/cm2 and –3.6×10-9 C/cm2 at 0.5 mW/cm2, while a short-circuit current flowed. The open-circuit voltage changed in accordance with accumulation charge Qs, and finally saturated. Modeling that accumulated negative charge is a source of space charge field and directly effects on the electrostatic energy stored in OSCs, dependence of the open voltage on the accumulated charge Qs was explained.
Optical and near-infrared observations of novae give us useful information for understanding the diversity of nova eruptions. Classical nova V1723 Aql was discovered by F. Kabashima and K. Nishiyama on 2010 September 11. We have conducted photometric and spectroscopic observations of V1723 Aql in both optical and near-infrared (NIR) wavelength regions since its discovery. The V-band decline time by 2 mag after the maximum, t2, was ~12 d. The apparent Fe II emission lines were also seen in the optical spectra. The Rc- and Ic-band light curves exhibited rapid declines (0.16 mag d−1 in Rc) 20 days after the visual maximum, while the NIR (J, H, and Ks) showed slow decline rates (~0.07 mag d−1). This rapid reddening suggests that dust particles formed during the very early phase of the expansion in V1723 Aql.
Results of our experimental investigation on the ozone zero phenomenon
suggested us the importance of the electrode surface condition. This means
that the main cause of the phenomenon, that is, temporal decrease of ozone
concentration at the outlet of DBD type ozone generator and the recovery
characteristics from the phenomenon are considered as the surface reaction
process, which are influenced strongly by the surface condition. The surface
condition is never constant during the ozone generation and varies gradually
or remarkably with time depending on the experimental conditions. Therefore
we have been continued to make clear the cause of the phenomenon, for
example, the reproducibility of the phenomenon, using new electrodes and
together with the surface analysis technique etc. In this paper, we describe
on the above results and discussion.
Ultra-thin hydrogenated amorphous silicon thin films have been deposited by thermal chemical vapor deposition (CVD) to prepare smooth top surface of the films avoiding the ion bombardment. Rapid thermal oxidation of thermal CVD a-Si:H results in nanocrystalline dots in the ultra-thin silicon films. Spectroscopic ellipsometry (SE) and high resolution transmission electron microscopy (TEM) have been used to investigate the optical and structural properties of both ultra-thin a-Si:H and nanocrystalline silicon films. To analyze the ellipsometric data of ultra-thin a-Si:H films, a new parameterization i.e., the combination of Sellmeier law and four Lorentz peaks, has been successfully introduced. Width of the Lorentz peaks are directly related with the change of optical functions with the thickness of a-Si:H films. It has been certified that the dense Si matrix with smaller degree of disorder is formed when the thickness exceeds 8nm and the films with the thickness of less than 3.8 nm becomes voided. To interpret the ellipsometric data for nanocrystalline silicon films, three layer model (SiO2, poly-Si+a-Si+void and SiO2) has been adapted. It is inferred from SE and TEM analyses that the size and the density of nanocrystalline dots can be controlled by the morphology of initial ultra-thin a-Si:H films and RTO conditions.
We have investigated the nanopatterning of chemical vapor deposited (CVD) diamond films in room-temperature nanoimprint lithography (RT-NIL), using a diamond nanodot mold. We have proposed the use of polysiloxane as an electron beam (EB) mask and RT-imprint resist materials. The diamond molds of cylinder dot using the RT-NIL process were fabricated with polysiloxane oxide mask in EB lithography technology. The dot in minimum diameter is 500 nm. The pitch between the dots is 2 μm, and dot has a height of about 600 nm. It was found that the optimum imprinting conditions for the RT-NIL : time from spin-coating to imprinting t1 of 1 min , pressure time t2 of 5 min, imprinting pressure P of 0.5 MPa. The imprint depth obtained after the press under their conditions was 500 nm. We carried out the RT-NIL process for the fabrication of diamond nanopit arrays, using the diamond nanodot molds that we developed. The resulting diamond nanopit arrays with 500 nm-diameter and 200 nm-depth after the electron cyclotron resonance (ECR) oxygen ion beam etching were fabricated. The diameter of diamond nanopit arrays was in good agreement with that of the diamond nanodot mold.
We annealed dispersions of microcrystalline Si in amorphous silicon by heating to 550 °C. The dispersions had been deposited by plasma-enhanced CVD from SiF4 and H2 at 250 to 290 °C. By X-ray diffraction and Raman scattering we observe an increase in crystal size and volume fraction. The electron mobility, measured by the Van der Pauw method, also was raised to a highest value of 91 cm2V−1s−1 at the electron density of 7.6×1017 cm−3.
The effects of thermal heat-treatment, N+ -ion, Ar+ -ion, γ-ray and electron-beam irradiations have been studied on MOCVD-grown ZnSe-ZnS strained-layer superlattices (SLSs) by means of low-temperature photoluminescence and X-ray diffraction measurements. As-grown SLS structure seems to be stable against the heat-treatment compared to ZnSe thin film, but after the defects are introduced in the SLS by irradiation, additional fluctuation at the interface between the ZnSe well and the ZnS barrier layers takes place. However, no significant intermixing and the changes of strain can be detected in the irradiated SLS.
As a new dielectric layer for magneto-optical disks, we have developed AlGeN films prepared by the reactive sputtering method. The deposition rate, internal stress, and refractive index were investigated as functions of the sputtering parameters.AlGeN films were found to be superior in these points: high deposition rate, low internal stress (<1.5×109 dyne/cm2), and high refractive index (>2.4).
To evaluate dynamic characteristics and reliability, magneto-optical disks with TbFeCo double layer sandwiched by AlGeN layers were prepared on the polycarbonate substrate. Those disks had high carrier-to-noise ratio (C/N) even for 0.7 6 μm recording bit length. The acceleration test at a temperature of 60°C and a relative humidity of 90% was carried out. The defect error rate remained constant up to 2000 hours.
High reliability and good dynamic recording characteristics of the magneto-optical disk can be achieved by use of the AlGeN dielectric films.
The electrical conductivity of nc-Si films grown from SiF4 and H2 with constant arsenic doping rises from 10-5 to 10 Scm-1 as the thickness rises from ˜ 0.1 to 1 μm. This variation demonstrates the strong influence of film structure on conductivity. We show that the conductivity of undoped nc-Si films of constant thickness can be varied by adding SiH4 to the SiF4 and H2 source gas.
High electron mobility transistors (HEMTs) with a pseudomorphically strained InAs channel (InAs-PHEMTs) were fabricated, and their high frequency characteristics were estimated by measuring the S-parameters. For a VDS of 1.4 V and VGS of 0.3 V, InAs-PHEMTs showed an excellent intrinsic cut-off frequency (fT, int.) as high as 90 GHz regardless of their longer LG (0.7 μm). Since fT is known to be inversely proportional to LG to the first approximation, fT, int. of our InAs-PHEMTs may reach 630 GHz if their LG is reduced to 0.1 μm.
Moreover, we calculated the InAs-PHEMTs' energy state and potential profile by self-consistently solving the Schrödinger and Poisson equations. In solving the Schrödinger equation, the energy-dependent effective mass was employed to take into account the strong non-parabolicity of InAs conduction-band based on the k·p perturbation theory by E. O. Kane. It was clarified that most electrons are confined to the InAs layer. On the contrary, if the non-parabolicity is not taken into account, electrons will spread over the InGaAs channel layer.
The characteristics of 1 MeV electron irradiated GaAs solar cells grown on GaAs and Si substrates are studied under dark and AM 0 conditions. The short circuit currents (Isc) for GaAs/GaAs cell and GaAs/Si cell have been decreased at higher fluences. The degradation rate of Voc and Pmax for GaAs/Si is slower than that of GaAs/GaAs at the fluence 1×1016 cm−2. This is due to the high radiation resistance of saturation current. It has been due to slow generation of arsnic vacancies related defect (VAs) in the GaAs/Si solar cell, which is determined by photoluminescence analyses and deep level transient spectroscopy.
The theory of particle diffusion in an electrostatic turbulent plasma is formulated by applying the direct-interaction approximation (DIA) to subensemble-averaged functions instead of conventional ensemble-averaged ones. This theory approximately incorporates the Lagrangian description into the DIA through decorrelation trajectories. The running diffusion coefficient is shown to be calculated by solving a nonlinear ordinary differential equation together with an equation for decorrelation trajectories and by averaging initial conditions at the starting point of trajectories.
An experimental study is carried out to clarify the mechanism of the ozone zero phenomenon. Temporal variations of both the discharge characteristics and the metallic electrode surface in the ozone generator are investigated by the Lissajous figure method and Auger electron spectroscopy (AES), respectively. The AES results suggest that a number of oxygen atoms penetrate into the stainless-steel electrode owing to the exposure to ozone. Such a surface change would result in the temporal variation of the discharge characteristics of the generator.
The poloidal electric field generated by electron-cyclotron resonance heating is investigated for a tokamak plasma in the collisionless regime. This poloidal electric field is calculated by solving an adjoint equation to the linearized Fokker-Planck equation with a quasi-linear diffusion term. It is found from this calculation that the magnitude and the sign of the poloidal electric field depend strongly on the values of the inverse aspect ratio, the poloidal angle of the absorption point, the parallel velocity of resonant electrons normalized by the thermal velocity, and the strength of the relativistic correction to the resonance condition.
Dome Fuji is potentially one of the best astronomical sites in Antarctic plateau. We have a plan to build a 2-m class infrared telescope at Dome Fuji, and have been evaluating the site since the 2006/2007 Antarctic summer. We present the outline of a 2-m class telescope project and some results of our SODAR measurements.