XPS studies of V2O5 thin film at different temperatures and oxygen partial pressures

Influence of surface diffusion on adsorption has been investigated by XPS studies of adsorption of O-2 on V2O5 thin film at different temperatures. The relative amounts of surface vanadium and oxygen species at different temperatures and oxygen partial pressures are obtained by XPS. An effective activation energy E-d of the dissociation reaction is introduced to determine the degree of layer-diffusion by analyzing its variation with temperature. The diffusion is little below 573 K, and becomes quite apparent above 673 K. The concentration of outermost surface O- increases with increasing oxygen partial pressures for temperature below 573 K, while above 673 K, no significant changes, which shows great influence of diffusion on adsorption. (C) 1998 Elsevier Science B.V.