Electronic and Geometric Structure of Supported Au Atoms and Particles as Model Systems for Heterogeneous Catalysts, a Review of Our Work: Can Surface Science Provide Important Information and a Perspective for New Information?

After a short introduction about the concept of model catalysis, there will be three subjects covered within this review and perspective, based mainly on our own research. The first one deals with atomic defects in thin oxide films, which are used to model the catalyst support, and their charge state as a function of film thickness. In a second section we review the properties of single metal atoms and metal clusters, where we concentrate on Au, which has been identified in the late 1980ies as a possible catalytic species. We show, how the shape of the clusters depends on the detailed structure of the oxide films, and how we can use the electronic structure, as observed by STM, to determine the number of atoms constituting the particle, even though the atomic structure cannot be resolved directly by topographic STM. In the third part we introduce a novel technique for vibrational structure determination. We call this technique surface action spectroscopy, which is based on a technique, called action spectroscopy, used to determine cluster structures in the gas phase. We show an example how the technique can be used in surface science to determine the structure of an oxide film support, and we suggest a way of how it could be used to study the structure of deposited clusters.