The Influence of Metal Substrates on the Electronic States of Metal Overlayers

The aim of this paper is to provide an introduction to the electronic structure of very thin film (one to ten monolayers) overlayers using examples from studies of Hg overlayers on Ag(100) and Fe thin film overlayers. Interracial states as a result of the interaction of the substrate and overlayer, as well as the new electronic states of the overlayer caused by a new crystallographic structure can modify the overlayer metal electronic structure. Additional changes in the overlayer electronic structure arise from the reduced dimensionality (2 dimensionality as opposed to 3 dimensionality) of the thin film. We discuss the photoemission techniques for determining the electronic structures of thin metal over layers. Layer by layer growth of the overlayer is important for such studies as is knowledge of the overlayer structure. We have summarized our current understanding of metal overlayers in tables and attempt to demonstrate that further progress in combining structural and photoemission studies is necessary for better fundamental understanding of metal overlayers