Photoemission study of Ag monolayer systems: Effects of the substrate

Angle-resolved photoemission was used to study Ag(111) monolayers on six different substrates: Cu(111), Cu(001), Ni(111), Ni(001), Au(111), and Si(111)-(7×7). Overlayers that are incommensurate with the substrate [Ag on Cu(111), Ni(111), and Ni(001)] or commensurate with the substrate only over a large unit cell [Ag on Cu(001)] show electronic structures essentially independent of the substrate orientation and material, except for an overall shift in binding energy. The overlayer electronic structure is somewhat different for the Ag/Au(111) system, where there is a nearly perfect overlayer-substrate lattice match as well as substantial overlap in energy bands of like characters. In the Ag/Si system, partially disordered overlayer growth and strongly corrugated substrate surface structure cause the overlayer features in the spectra to broaden substantially.