Surface diffusion of carbon on (111) platinum

An Auger electron spectrometric technique has been employed to measure the diffusivity of carbon atoms on an otherwise clean Pt(111) surface. The technique used was essentially a classical mass transport method, in which the rate the migration of carbon atoms out of a circular surface region initially containing a monolayer of adsorbed carbon was measured by Auger electron spectrometry. The diffusivity D can be characterized by an Arrhenius equation D=D0exp(—ΔH*/RT) in which D0=0.2 cm2/s and ΔH*=31±4 kcal/mol. Additional data are presented to demonstrate the self-consistency of the experimental method used.