Atom Incorporation at Edge Defects in Clusters

Abstract

Theoretical estimates indicate that atoms originally deposited on top of a surface cluster have a significantly lower energy barrier to incorporation at edge defects compared to attachment at straight steps of sizable clusters. We have carried out the first test of these findings, by field ion microscopic observations of the behavior of Ir atoms on Ir(111) clusters with and without defects in the edges. The clusters Ir18, Ir19, Ir20, Ir55, and Ir63 have been examined. Our observations suggest that defects do not provide especially low energy paths for incorporation, which generally occur in straight steps.