Low-energy electron microscopy of CO/Pt(111) surface diffusion by nonequilibrium coverage profile evolution

Abstract

The adsorption and diffusion of CO molecules on a Pt(111) surface have been studied using low-energy electron microscopy (LEEM). The explicit relationship between LEEM image intensity and CO coverage that is determined during adsorption is used to characterize nonequilibrium CO coverage profiles that are subsequently prepared by laser-induced thermal desorption. Real-time observations of the temporal evolution of these profiles toward equilibrium uniform coverage distributions are analyzed by predictive and inverse solutions of the diffusion equation. These two methods determine consistently the detrimental effect on diffusion of the laser-induced surface damage that is observed directly with LEEM. The inverse method also provides independent information on the coverage dependence of diffusion with high coverage resolution.