After describing briefly the principle and techniques of ellipsometry, the authors review the recent developments in ellipsometric studies of films and surfaces with comments on future possibilities. The items covered are: determination of optical constants, observation of transition layers, adsorption studies, work on oxidation and corrosion of solid surfaces, and others.
The diffraction patterns of circular apertures with a non-uniform amplitude filter proposed by Asakura are experimentally studied by using an optical diffractometer. The results are compared with his theoretical work published in this journal (Oyo Butsuri 32, 180, 653 (1963)).
Images obtained in thermal neutron radiography by the use of a small nuclear reactor are analyzed by the technique of Fourier analysis. The optical transfer functions unparallel neutron beam and for the process image transfer from an activated In film to an X-ray film are derived and compared with experiment. The spurious resolution of image expected from the shape of the optical transfer function is observed.
Some characteristics of “channel” electron multipliers are measured and compared with the relation calculated by a simplified analysis. Two kinds of materials, ferro-chrome alloy thin film evaporated on inner walls of a glass tube and “Epoxy” resin containing graphite by 30%, are used as secondary emission materials of high resistance. When evaporated films are used as continuous high resistive film surfaces, “ring” electrodes are introduced in order to make the electric field in the channel uniform. Tubes of 3mm in inside diameter and 60cm in length give gains up to 102. By taking into account the energy distribution of secondary electrons, the calculated relation of the gain to the applied voltage is found to be in fairly good agreement with experimental result.
Magnetic hysteresis loops and torque curves have been measured on natural single crystals of α-Fe2O3 obtained from various localities and on synthetic polycrystalline specimens of α-Fe2O3. The weak ferromagnetism observed on Shimotokuyama and Ayumikotan natural crystals behaves as predicted by Dzyaloshinsky and Moriya, while Wagasennin and Elba natural crystals possess a different magnetic property. The difference seems to be related to the origin of the natural crystals. At room temperature, polycrystalline sintered specimens of pure α-Fe2O3 have a hysteresis loop characterized by high coercivity and linearity of the first quadrant portion of its descending branch. This shape is attributed, to the nature of the weak ferromagnetism. The observed values of the coercive force and the rotational hysteresis loss of the polycrystalline specimens are interpreted in terms of a restrictive force due to exchange interaction operating across the grain boundary.
Cadmium oxide crystals are prepared by reacting cadmium vapor with oxygen at temperatures of 870°K_??_970°K. Their growth is in the forms of needles, plates, cubes, swords and twined dendrites. Measurements of the electric conductivity and the Hall effect made on needle-like crystals at temperatures between 4°K and 600°K show that the specimens are fully degenerated n-type semiconductors and possess the free electrons of the order of 1018cm-3 in concentration and of about 500cm2volt-1sec-1 in Hall mobility. The free electrons are probably originated from nonstoichiometric excess of Cd atoms which are situated at interstitial positions. From the change in electric conductivity with annealing temperature, the formation energy of interstitial Cd atoms is estimated at 0.53eV. The activation energy of mobility of interstitial atoms is estimated at 1.67eV from diffusion constant. The dependence of the conductivity on the partial pressure of oxygen at 920°K is expressed in terms of the relation σ_??_P02 -1/6.0. This shows that one excess Cd atom produces just two free electrons.