A simple model was proposed in order to explain qualitatively the results of a field ion microscopic study in which a substitutional Ir atom on a Rh(001) surface had trapped diffusing Rh adatoms. The proposed explanation was supported by an embedded atom simulation studies of the effect of a substitutional Pt atom, in a Pd(001) surface, upon Pd adatom diffusion. A smaller energy barrier was found for a single adatom to diffuse around the defect than away from it. Thus, the adatom was effectively trapped by this defect; in qualitative agreement with field ion microscopic results. It was also found that Pd adatom clusters were more strongly bound at the defect, than away from it; thus indicating that such a defect could act as a nucleation site for cluster growth.

M.C.Fallis, A.F.Wright, C.Y.Fong, M.S.Daw: Surface Science Letters, 1994, 311[3], 717-23