A monodisperse colloid is expected to behave like atomic systems because the particles under go thermal motion. It shows phase transition from disordered phase to ordered phase. Changing its appearance from milky white to iridiscent, the iridiscence produced by the Bragg reflection of visible light by the orderely arranged particles. If the particles are large enough, they can be seen by a light microscope used in metallurgy. Several micrographs of the ordered phase (or crystalline structure) are shown. The mechanism of the transition is quite different from those seen in ordinary atomic systems, in which attractive force plays an important role. The difference is caused by repulsive force between the particles and explained as the realization in a colloidal system of the so called Alder transition, which was found by computer experiment.
Thin films were obtained from the vacuum evaporation of Ga2Se3, and were investigated for their electric properties. The obtained results are: 1) The thin films consisted of hexagonal crystalline GaSe, when Ga2Se3 was vacuum evaporated on the substrate kept at temperature above 200°C. 2) The crystal line GaSe had a layered structure, its C axis being perpendicular to the substrate plane. 3) For the crystalline growth, Frank-van der Merwe's mechanism was almost matched. 4) The films behaved as p type semiconductors and their acceptor levels were estimated to locate at 0.41-0.44 eV above the valence band. 5) The resistivities of the films were decreased in accordance with increase of the hole mobility, when the substrates had been kept at higher temperature at the vacuum evaporation. 6) The fill factor was 0.32 for a p-n GaSe junction cell obtained by the vacuum evaporation.
Catalytic properties of supported Fe, Co, and Ni bimetallic catalysts were examined with XPS, XRD, and IR. From the XPS and catalyst's XRD measurements, it become evident that the reducibility of iron or cobalt was enhanced by alloying with nickel. This reducibility enhancement suggests that hydrogen is easily activated on the catalyst's surface. Infrared spectra of NO adsorbed on bimetallic catalysts depended on the metal composition. The conversion of CO was related with the absorbance of bent-type NO. Adsorption sites of bent-type were expected to be active sites in CO hydrogenation because of its high electron density. The alloying metals increased the absorbance of bent-type resulting in high CO conversion and high selectivity to higher hydrocarbons.
A combined system of Raman spectroscopy and ellipsometry is developed for the study of catalyst surfaces on which a chemical reaction is taking place. A surface layer or a surface compound produced in the reaction is analyzed by an ellipsometer and a Raman spectrometer, the products in gas phase by a mass spectrometer, and the surface species by the Raman spectrometer. A special reaction cell is designed for the optical measurement under high temperature-high/normal gas pressure conditions. The Boudouard and dissociation reactions of CO molecules on Fe and Fe3O4 catalysts are studied. A surface layer produced by diffused C and O atoms and a thin oxide layer formed during the CO dissociation reaction are observed, and their thicknesses and the dielectric constants are determined. Raman spectra reveal several kinds of carbon species such as a defective graphite, an Fe carbide and an unstable surface graphite formed on the Fe and Fe3O4 surfaces. The reactivity of those species with H2O is studied.
An ECD device using composite films consisting of viologen polymer complex (polyion-complex of polymerized viologen and polystyrene-sulfonic acid) and conductive powder (SnO2/TiO2) has been obtained with excellent charactristics. The porous structure of composite films enables electrolyte to permeate into the film easily to give more effective electrochemical reaction, and surface of the conductive powder becomes working electrodes. Dispersed states of viologen polymer on the consuctive powder can be evaluated from the v-Ip relationships of cyclic-voltammograms. The increase in thickness of the composite film changes only scarcely it's electrochemical characteristics which are similar to the thin-film characteristics. On the other hand, the increase in polymer content of the composite give the thick-film characteristics of electrochemical reaction. As composite films with smaller viologen polymer content gives faster response time but smaller contrast ratio to the device, there is an optimum polymer content for the composite.
To simulate electrical breakdown phenomena occuring on an anode in vacuum gap, energies and mass species of ions emitted from target electrodes bombarded by 2 and 3 keV electron beams are measured. Target materials used were Al, Cu and Fe. Ions emitted had their kinetic energies of several eV, which coincides with results obtained from dc vacuum prebreakdown measurements. Dominant mass species of emitted ions are H+ and H2+, and sometimes H2O+, O+. From these results it is pointed out that electron impact desorption on an anode of a vacuum gap is one of the most important phenomena which govern electrical breakdown in the gap.
Excited states of CO adsorbed on metal surfaces have been receiving considerable attention. Such states play important roles in a variety of surface dynamic processes, i.e., electron or photon stimulated desorption, etc.. Recent re-assignments of valence excitations with electron energy loss measurements of CO with metal surfaces have been discussed on the basis of the results calculated in terms of molecular orbital methods by Kawaguchi and Freund et al..