Interaction of carbon disulphide with evaporated films of iron, nickel and lead

Abstract

The interaction of CS₂ with evaporated films of iron, nickel and lead has been studied from a temperature of –80 to about 300°C. Rapid chemisorption and incorporation took place on iron at –80°C, but on nickel the reaction was limited exclusively to the surface phase. Above 25°C extensive incorporation occurred in both iron and nickel, the latter was shown to be more reactive toward CS₂ than the former. The rate of incorporation depended directly on the first power of CS₂ pressure and the activation energy, which was independent of the thickness of the “product-layer”, was 9 kcal mole^–1 on nickel but only 4.5 kcal mole^–1 on iron. The rate-determining step appeared to be the adsorption of CS₂, probably with dissociation into carbon monosulphide and sulphur. With lead, only physical adsorption occurred at –80°C and no chemisorption was observed at any temperature up to 250°C.

Adsorption at –80°C on films which had been saturated at 25°C with oxygen was mainly physical. The completion of the chemisorbed layer on oxidized iron and nickel above 100°C was followed by the formation of the bulk compounds; the activation energies of incorporation were 14 and 4.0 kcal mole^–1 respectively.