Seed crystals of diamond were grown by the temperature-gradient method using a metal flux, and features of their growth were investigated under a condition where metastable graphite crystallized remarkably. Graphite crystallizes in greatest number in a sample with only one seed on the seed bed, while little, with four seeds. Total weight of grown diamond and crystallized graphite increases with growing time, at a constant rate which is independ-ent of the number of seeds in a sample. No graphite crystallizes in a region around the seed, and the metastable crystallization of graphite can be avoided by covering the seed bed with such regions. On the other hand, an increase in growing pressure can essentially suppress the crystallization of graphite.
A novel preparation technique of thin films has been successfully developed with an extremely high deposition rate by high-density, high-temperature plasma produced by an intense pulsed ion beam (940 keV, 7kA/cm2, 30 ns). Such a beam has been irradiated onto the surface of ZnS target to produce the zinc and sulfur plasma, which expands to be deposited on the substrate. The temperature of the plasma has been evaluated to be _??_1eV under the assumption of a thermal equilibrium. We have calculated the deposition rate (instantaneous) to be _??_2.3cm/s, which exceeds five orders of magnitude higher than that of a conventional vacuum-depostion technique. From the measurement of X-ray diffraction, clear evidences have been obtained for the production of polycrystalline hexagonal-ZnS thin films. Several dependence such as deposition rate, crystal-linity, etc. has also been studied on the temperature of the substrate.
A 612 nm iodine stabilized He-Ne laser has been designed and constructed. The 612 nm line was selected by means of a Brewster prism placed in a laser cavity. Seven oscillation lines such as 594 nm, 604 nm, 612 nm, 629 nm, 633 nm, 635 nm and 640 nm could be observed by using the laser system without the iodine cell. The whole 21 components (“a” to “u”) of 127I2, transition 9-2, R (47), could be obtained by the third harmonic technique. In the frequency locking case to “o” component, the frequency stability was estimated to be 1.6×10-12 (τ=1000 s). The frequency variation of the two similary constructed 612 nm stabilized He-Ne lasers was estimated to be 1.8×10-10.
Poly (3-dodecylthiophene) with a fractal pattern has been successfully prepared by an electrochemical method at the liquid-gas interface. At the applied voltage of 10 V, its fractal dimension indicates a maximum value 1. 64±0.03 which nearly coincides with the theoretical value 5/3 expected from a DLA model. At lower voltages, the growth is controlled by diffu-sion of monomer molecules and electrolyte ions. However, at higher voltages, field assisted drift seems to play roles. The conductivity and the growth rate etc. have been found to be related with fractal dimension. At higher applied voltages, an undoped region has been seen to appear in the middle part of branches, which has influenced the growing speed of the tip of growth. By shortening the circuit, the undoping initiated from the tip of the growth and proceeded to the center.