Structure and dynamics of metal single crystal surfaces

The structure of Au(100), Au(111) and Pt(100) in contact with aqueous solutions and the change with electrode potential has been studied by insitu STM. While the gold single crystal surfaces after flame annealing exhibit the very same type of reconstructions as obtained in UHV studies, a surface structure is observed for flame-annealed Pt(100) that is distinctly different fi om the well-known (hex) structure of UHV-prepared Pt(100) crystals. Lifting of the reconstruction leads to monoatomic high islands on the surface which are ideal test objects for the study of surface dynamics. In the case of gold an anion-enhanced surface mobility causes the islands to disappear by rapid coarsening, whereas such an electrochemical annealing is not observed for Pt(100). Because of a very low surface mobility, the Pt(100) surface after lifting of the reconstruction retains its high density of islands and hence has a high defect density. The consequences for electrochemical studies with flame-annealed Pt(100) are briefly addressed.