Surface States on Clean and Adsorbate-Covered Metal Surfaces

Abstract

We review our research activities that cover the preparation and characterization of clean metal surfaces and monolayer films in view of using them as a convenient laboratory for studying and manipulating electronic properties in two or less dimensions. In particular, the interactions of surface states with adsorbed molecular and atomic layers, as well as with periodic arrangements of steps as conveniently found on vicinal surfaces, are studied. Photoemission intensity mapping is used in order to map out Fermi surface contours and band dispersions of these systems. The following examples will be discussed: Na adsorption on Al(001) occurs in two different structures, both with a c(2×2) symmetry, depending on the temperature. The Al(001) surface state reveals its different contributions to the chemical bonding in the two situations. On hydrogen-saturated Mo(110) a previously observed phonon anomaly can be related to the occurrence of nested features in the surface state Fermi surface with the proper nesting vectors. On vicinal Cu(111) surfaces the interaction of the Shockley surface state, forming a two-dimensional electron gas, with clean and decorated steps is monitored.