Systematic studies on surface modifications by ARUPS on Shockley-type surface states

The quasi two-dimensional surface state on noble metal (111)-surfaces can be used as a sensitive probe for different surface modifications, adsorption processes, and interactions between adsorbate and substrate. Already one monolayer of physisorbed Xe on Au(111) is responsible for a characteristic shift of the Shockley state towards the Fermi level and the surface state experiences an increase in spin-orbit splitting of up to 35%. In contrast to the physisorption process of rare gases, a sub-monolayer coverage of an alkali metal, e.g., Na on Au(111), has the opposite effect on the Shockley state, i.e. an increase in binding energy, until it reaches the bottom of the L-gap and vanishes into the bulk states. Additionally.. we studied the intermetallic system Ag/Au(111) which differs substantially from the other systems because of the similarity in the electronic structure between substrate and overlayer. (c) 2006 Elsevier B.V. All rights reserved.