ATOM CONDENSATION ON SURFACE CLUSTERS - ADSORPTION OR INCORPORATION

Condensation of thermal energy atoms on clusters present on a crystal surface is a process significant for the low-temperature growth of cry stals. It has been examined by measuring the spatial distribution of s ingle Re as well as Ir atoms evaporated onto Ir clusters containing le ss than 60 atoms, maintained at T similar to 20 K on Ir(111). Re atoms are found to penetrate into clusters, exchanging places with high eff iciency with cluster atoms at edges made up of {111}, but not {100} fa cets. With Ir atoms, only adsorption on top of the clusters, without p enetration into the lattice, is observed.