Measurements were made of surface self-diffusion on (100), in aqueous 50mM H2SO4, by means of electrochemical atomic force microscopy. It was found that a diffusivity minimum appeared near to the zero-charge potential (0.27V) for the (100)-(1 x 1) surface. This minimum diffusivity (10-15cm2/s) agreed well with the value that was extrapolated from vapor-phase experiments. The results showed that the potential dependence of the diffusivity could be explained by considering not only anion adsorption but also the role that was played by excess charge densities, at the (100) surface, in altering the Au-Au interatomic bonds.

N.Ikemiya, M.Nishide, S.Hara: Surface Science, 1995, 340, L965-70