Toshio Sugita

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.

A Pore-Scale Numerical Simulation Method for Estimating the Permeability of Sand Sediment

A numerical method system to estimate the permeability of sand sediments, at a microscopic scale, was developed. Initially, 3D geometrical representations of the sand grains are reconstructed from a series of 2D X-ray CT scans of real sand grains. 2D cross-sectional slices of the grain outlines are combined together to produce 3D objects via spherical harmonics series expansions. Then, the reconstructed sand grains are packed randomly inside a cubic, microscopic, domain by a combination of a growth method and a simulated annealing method to achieve a predefined porosity. Finally, a single-phase water flow within the domain was simulated numerically, using the lattice Boltzmann method. The calculated permeability of these systems compares well with the values provided by conventional theoretical models. One of the contributions of this study is to show that it is possible to predict the permeability of sand sediments of variable porosities, using sand grains from CT images with changing size distributions and orientations.

Planning of synthetic diamond film by the Penning discharge microsputtering method

Abstract A new method for planning diamond film surfaces was developed. The Penning discharge microsputtering (PDMS) method, produces mainly neutral particles which bombard rough diamond films and smooth the film surface. This method was tested on synthetic diamond film obtained by microwave plasma chemical vapour deposition and was evaluated by scanning electron microscopy and scanning tunnelling microscopy observations of the changes in surface profile. Processing for 60 min reduced the arithmetical mean deviation Ra of the film from 0.22 to 0.10 μm. Spectrophotometric measurement of the light transmittance of the film confirmed an improvement in transmittance of the film over a broad range from UV to IR.

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.

Pattern marking on synthetic diamond film by Penning discharge sputtering

Abstract Method and apparatus to perform micro-etching and micro-inlay of patterns and numerals on synthetic diamond films by Penning discharge sputtering has been developed and evaluated. In this apparatus, selection of etching and inlay modes are made by a change of anode position. In etching mode, etching beam originates in a Penning discharge space and is guided through a duct in order to reach the diamond film surface covered with a pattern mask and then forms an etching pattern on the surface. After the etching is made, a new position of anode is selected for inlay process and the metal atoms that sputtered from the cathode surface through the duct deposit on the previously etched portion on the diamond film. A 5.3 μm thick diamond film formed by microwave plasma CVD. A flat dish-shaped etching of 2.5 mmφ and a same size inlay with gold were made with a mask having 2.5 mmφ hole and gold cathodes. In this case, etching rate of diamond film is 0.07–0.12 μm min −1 and deposition rate of gold 0.06 μm min −1 . By the same technique, etching and gold inlay shaped after the numeral “5” with 120 μm in width and 180 μm in length was produced.

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.

Erratum: Clean Up of Inert Gases in a Penning Discharge Studied by a Tracer Technique

In order to obtain further information of the pumping action of a diode getter ion pump for inert gases, the clean up of inert gases, principally the ion sputtering patterns on the cathode and the location of ion on each electrode, has been observed for pumps with various cells by the use of radioactive tracer Xe131m. The radioactivity of each electrode was counted by a G‐M counter. Inert gases are cleaned up principally at the cathode; about 20% as much is cleaned up at the anode.

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.

Pumping Characteristics and Application of Getter-ion Pump

With the advent of getter-ion pumps, it seems worthwhile to examine its pumping behaviour and effect on the residual gases within glass-metal vacuum system.A titanium getter-ion pump similar to the cold cathode “VacIon” type developed by Hall and the ultra-high vacuum mass spectrometer designed for the study of surface phenomena in ultra-high vacuum were chosen for this purpose.Some pumping characteristics of a getter-ion pump and vacuum phenomena in bakeable glass-metal lsystam evacuated by getter-ion pump at various baking conditions have been investigated.