The sub-monolayer deposition of Co on Pt(111) was studied by scanning tunneling microscopy at room temperature. It was found that deposition onto a surface with adsorbed CO (saturation coverage) led to an island density which was almost 10 times as high as that which resulted from deposition onto the clean Pt surface. On the basis of nucleation theory, this was explained as being the result of a reduction in the diffusion coefficient of Co adatoms, in the presence of CO, by more than 2 orders of magnitude. This effect was attributed to the displacement and/or rearrangement of CO molecules which was necessary when Co adatoms diffused over the crowded surface.

Slowing down Adatom Diffusion by an Adsorbate - Co on Pt(111) With and Without Pre-Adsorbed CO. R.Kalousek, M.Schmid, A.Hammerschmid, E.Lundgren, P.Varga: Physical Review B, 2003, 68[23], 233401 (4pp)