Adsorption and incorporation on copper

Abstract

The interaction of H2S, H2Se, AsH3, HCl, SO2, CS2 and N2O with evaporated films of copper has been studied in the temperature range –80 to 250°C. Weak reversible adsorption of CS2 and SO2, and mainly dissociative chemisorption of H2S, H2Se, AsH3 and HCl took place at –80°C. The extent of N2O adsorption on a Cu film at this temperature was negligibly small. The completion of the surface layer on a Cu film by either H2S, H2Se or AsH3 at temperatures –80°C was followed by the formation of bulk compounds and the process was accompanied by H2 evolution; the activation energies of the incorporation processes were estimated from the rates of adsorption at different temperatures but virtually the same surface coverage. Dissociative chemisorption of N2O on Cu film above 30°C was very slow and proceeded to only a limited extent. Cu did not chemisorb CS2, SO2 or HCl at any temperature in the range 30 to 250°C. The latter four gases were circulated over a heated W filament before reaction with the Cu film. The rate of uptake of the gas was a function of its pressure and the temperature of both the Cu film and the W filament. Activation energies were determined from the rates of adsorption at different temperatures either of the Cu film or of the W filament. Extensive incorporation of the gas was then possible at as low film temperatures as –80°C.