Gas adsorption upon electrically conducting films during their condensation from molecular rays

Abstract

Listen

Translate article

If two or more components in a gas mixture are simultaneously adsorbed upon a solid boundary, the resulting surface structure is not necessarily a simple mixture of the layers which each gas would contribute by itself. For instance, adsorbed molecules of each component may alter the rates of evaporation of the other components from the surface, and also their mobilities in migration along the surface, even if none of them react chemically while adsorbed. Hence the kinetics of interfacial layers on solids exposed to mixtures becomes prohibitively complex as a general problem. When, however, one component is a metallic vapour and the other is one of the gaseous impurities common in vacuum technique, the practical results of contamination of the former by the latter are often so important as to demand the empirical investigation of individual details in advance of any general treatment. The detail chosen in the present paper is the effect of certain gases on the electrical conduction of a metallic layer deposited from the vapour phase. There is considerable evidence that a metallic vapour adheres differently to surfaces covered with various impurities, and such gas coverings may also be expected to have profound influence upon the lateral diffusion which has recently been proved to play an essential part in the building up of a crystalline solid. The electrical conductivity of such metallic deposits is known to be very small and uncertain compared with that of the bulk metal, and to vary discontinuously with several conditions; in particular it exhibits anomalies in ageing, in temperature dependence, etc., many of which are commonly stated to be “probably due to occluded gas.”