Local electron states and surface geometry of Si(111)-3 3 Ag

Scanning tunneling microscopy and current-imaging spectroscopy are used to determine the local structural arrangement and stoichiometry of 3 × 3 Ag on Si(111). The nature of the local electronic structure and the spatial character of the wave functions observed on an atomic scale lead to a structure consisting of Ag trimers embedded in a Si honeycomb formed by threefold-coordinated Si atoms. © 1987 The American Physical Society.