Field-ion microscopy was used to map the surface sites, which were visited by an individual Pt adatom that was migrating on the (001) plane at 175K, and to determine the activation energy for surface diffusion. Atomic displacements were found to occur only in the [100] or [010] directions. A surprisingly low activation energy (0.47eV) was found. The results were consistent with a model in which diffusion occurred via an adatom-substrate exchange mechanism. This mechanism was predicted theoretically for self-diffusion on Al(001).

G.L.Kellogg, P.J.Feibelman: Physical Review Letters, 1990, 64[26], 3143-6