Surface enrichment and electronic structure of liquid Ag and Ag-Cu alloys

Abstract

Photoemission data obtained from liquid Ag and liquid Ag-Cu alloys are presented. The results allow the valence electronic structure of the Ag-Cu system to be studied over the entire concentration range without possible complications from mixed phases, or from matrix elements associated with k conservation. The relatively high photon energies (21-2 eV) allow observation of the whole band enabling the behaviour of the overlapping 3d and 4d resonances to be followed. Evidence for preferential surface enrichment of Ag at the expense of Cu is presented. Agreement with the pairwise bond model of Williams and Nason is obtained if surface relaxation of the Ag-Ag bond is allowed.