Shigeo Ebisawa

Adsorption and Oxidation of Carbon Monoxide on Clean Films of Palladium and Nickel

The adsorption and surface reaction of carbon monoxide and oxygen on clean films of palladium and nickel at room temperature at pressures in the range of 10−9−10−2 torr were studied by means of mass spectrometer and by measuring simultaneously electrical resistance.CO preadsorbed on clean films of palladium and nickel reacted readily with gaseous O2 and no induction period was observed. Oxygen preadsorbed on palladium film immediately reacted with CO, but on nickel never reacted.Some discrepancies between the results and those in the literature were discussed.

Adsorption of CO, O2 and CO2 on Titanium Film by Electrical Conductivity Measurements

The variation in the electrical resistance of titanium film due to the adsorption of such gases as carbon monoxide and oxygen is measured to make clear the binding states of adsorbed gases through the electronic interaction. Furthermore, the adsorption of carbon dioxide on clean film of titanium at room temperature is studied by means of mass spectrometry and by measuring simultaneously electrical resistance. From these measurements, it is considered that CO2 is dissociated into CO and O on titanium film and CO formed by the dissociation has two different binding states of adsorption on the film.

Metal Film Sputtering Technique to Coat Teeth for Preventing Dental Caries. A Preliminary Study

Dental caries starts locally on a tooth surface; thus, the selective protection by metal films on pits and fissures is simple and effective. The method and apparatus for forming preventive coatings by sputtering are described wherein metal atoms originate in a Penning discharge space and are then guided through a duct in order to reach a tooth and then to form a spot coating on the surface. A compact-size sputtering apparatus for the coating of a gold film on a surface of extracted teeth or glass substrates has been designed and the film-deposition characteristics examined. The typical deposition rate is 1 nm/s for a 6-mm film on a glass substrate. After gold films are coated on extracted teeth, the teeth are immersed in an 0.1 mol lactic acid solution (pH=4.0). The obtained results indicate that a thickness of about 200 nm is necessary and satisfactory for protecting against dental caries in vitro.

Industrial fine adjustment of the resonant frequency of a quartz crystal wafer by penning discharge sputtering

Abstract In the process of industrial preparation of quartz crystal oscillators, fine adjustment of the resonant frequency of the crystal wafers is usually performed by the evaporation technique; one surface of the base electrode of the wafer is exposed to the evaporation source and small quantities of metal film are repeatedly deposited on it until the resonant frequency reaches the desired value exactly. However, the evaporation technique is not always satisfactory because the deposition rate is too high fine adjustment and the film formed on the metal electrode is not strong enough. Thus, the authors developed a fine adjustment method with Penning discharge sputtering. The results obtained indicated that for a spot-sized gold film, the speed of fine adjustment was 0.14 kHz/s and the frequency shift after an annealing process (150°C, 5h) was as small as 3 ppm, and the adherence of the film was improved. As the results were significant for practical manufacturing purposes, a pilot apparatus for industrial use was developed.

Adsorption and Replacement of CH4, CO and NO on Evaporated Films of Titanium and Tungsten

The adsorption, surface reaction and mutual replacement of CH4, CO and NO on the films of titanium and tungsten evaporated under ultra-high vacuum condition have been studied with a combined Knudsen flow capillary method and mass spectrometer system. When CH4-covered surfaces are exposed to gaseous CO or NO at room temperature and 77 K, the appearance of both CH4 and complex produced by the reaction of CH4 with CO or NO in the gas phase is noted. However, when the surface with preadsorbed CO or NO are exposed to gaseous CH4, CH4 does not remove CO, NO and the complex from the surfaces.