Lattice dynamic study on 3d transition metal intercalates M x TiS2 (M=Mn,Fe, Co,and Ni) using point-contact spectroscopy

The derivatives of the current-voltage characteristics of a homojunction point contact of 1T-CdI₂-type layered crystal TiS₂ and its intercalation compounds M_1/4TiS₂ (M=Mn, Fe, Co, and Ni) have been measured at 1.4 K. With reference to the available data on lattice dynamics, we have identified various inter- and intralayer acoustic and optical phonon modes. The acoustic phonon modes are strongly anisotropic compared with the optical ones in these materials. The variations of the acoustic phonon energies upon intercalation of 3d metals are strongly correlated with those of the interlayer spacingc, for which qualitative discussions are given.     

Diffusion of disperse dye in atactic polystyrene

Sublimative desorption experiments were carried out on atactic polystyrene containing p-nitroaniline, p-aminoazobenzene, or C.I. Disperse Yellow 7 at 114°–170°C (above the T_g of the polymer). The diffusion coefficient of each dye in the polymer increased monotonically with rise in the desorption temperature. The mode of this change was exactly expressed by a WLF relation having the universal parameters given for amorphous polymers. The value of B_d, defined as the ratio of diffusional penetrant volume to that of a segment of the chain molecule, varied from 0.37 to 0.70 for the different dyes used. It is also shown that the B_d value is related to the logarithmic rotational volume of the dye molecule estimated from a molecular model.     

Maximum measurable distances for a single-mode optical fiber fault locator using the stimulated Raman scattering (SRS) effect

Maximum measurable distances for a single-mode optical fiber fault locator using the stimulated Raman scattering effect were calculated. Calculations were carried out on the assumption that the light source is an Nd:YAG laser operating at 1.06 μm and the photodetector is a germanium avalanche photodiode (Ge-APD). The first to the seventh Stokes lights can be detected by the Ge-APD. Calculations show that a break can be measured in an up to 165 km long ultra-low-loss single-mode fiber.     

Photo-induced change in wettability and binding ability of azoaromatic polymers

Photochromic polymers containing p-phenylazoacrylanilide were synthesized and the photo-induced hydrophobicity change on the surface of the polymer film was studied by measuring water wettability. The wettability increased with UV irradiation and returned to the original value with visible light irradiation. This photo-induced reversible change in wettability was considered to be caused by the large change of dipole moment across the azo bonds due to the isomerization of azo dye from trans to cis form. Furthermore, the photoresponsive polymeric adsorbent prepared from the azo polymer having adsorption behavior of a low molecular weight compound was studied. The binding ability of this polymeric adsorbent was decreased by UV irradiation. These results were attributed to the decreased hydrophobic interaction between the adsorbent and the adsorbate.     

Vapor-liquid equilibria of some pollutants in aqueous and saline solutions Part I: experimental results

Vapor-liquid equilibria were measured for dilute aqueous solutions of formic acid, acetic acid, pyridine, aniline, isobutyl alcohol, isoamyl alcohol, n-butyl acetate, dimethyl phthalate, diethyl phthalate and dioxane, respectively, at various pH, temperatures and concentrations of sodium chloride.The substances chosen are very important raw materials or intermediates in chemical industry and are widely used. Phthalates are used as plasticizers and leach, in small amounts, into water from plastics. Recently in Japan, we are recognizing phthalates as a new polluting material in sea water and river water.The vapor-liquid equilibria were severely affected by the pH of the solution, not only for the electrolytes (such as formic acid and pyridine), but also for esters. This is probably due to the effect of pH on the degree of the dissociation of electrolytes and on the hydrolysis of esters. The phase equilibria of some organic materials which are less soluble in water (such as phthalates and higher alcohols) were greatly affected by the salting-out effect of salinity.If the feed sea water to distillation plants is contaminated by volatile organic materials, some of them concentrate in the distilled water. Therefore, attention must be given to the properties of volatile, polluting materials in sea water when the product water from desalination processes is for human consumption.     

Submicrometer poly-Si CMOS fabrication with low-temperature laserdoping

The laser doping process for submicrometer CMOS devices with leakage currents as low as 10^-12 A/μm for both n-channel and p-channel devices is discussed. The I-V characteristics are comparable to those of poly-Si devices fabricated using ion implantation and high-temperature annealing processes. The laser-induced melting of predeposited impurity doping (LIMPID) process was used to fabricate submicrometer polycrystalline-Si CMOS devices. This process uses a very low temperature, so no dopant atom can diffuse along the grain boundaries in the solid region. The use of stacked Al/SiO₂ films as a protection layer made it possible to reduce the leakage current from several tens of picoamperes per micrometer to 1 pA/μm     

High energy-resolution electron energy-loss spectroscopy study of the dielectric properties of bulk and nanoparticle LaB6 in the near-infrared region

The dielectric properties of LaB₆ crystals and the plasmonic behavior of LaB₆ nanoparticles, which have been applied to solar heat-shielding filters, were studied by high energy-resolution electron energy-loss spectroscopy (HR-EELS). An EELS spectrum of a LaB₆ crystal showed a peak at 2.0 eV, which was attributed to volume plasmon excitation of carrier electrons. EELS spectra of single LaB₆ nanoparticles showed peaks at 1.1-1.4 eV depending on the dielectric effect from the substrates. The peaks were assigned to dipole oscillation excitations. These peak energies almost coincided with the peak energy of optical absorption of a heat-shielding filter with LaB₆ nanoparticles. On the other hand, those energies were a smaller than a dipole oscillation energy predicted using the dielectric function of bulk LaB₆ crystal. It is suggested that the lower energy than expected is due to an excitation at 1.2 eV, which was observed for oxidized LaB₆ area.     

Strain analysis of arsenic-doped silicon using CBED rocking curves of low-order reflections

Local lattice strains of semiconductor devices have been so far examined using higher order Laue zone (HOLZ) line patterns of convergent-beam electron diffraction (CBED). Recently, strain analyses in highly strained regions near interfaces have been reported using split HOLZ line patterns. In the present paper, it is demonstrated for arsenic-doped silicon that the use of CBED rocking curves of low-order reflections provides a promising new tool for the determination of strain distributions of highly strained specimen areas. That is, the anomalous intensity increase in the CBED rocking curves of low-order reflections is explained using a model structure with a strain gradient in the electron beam direction, which is similar to the models used for the split HOLZ line patterns.