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Abstract

We discuss in this paper two case studies related to nano-particle catalyst systems: one concerns a model system for the Cr/SiO₂ Phillips catalyst for ethylene polymerization. Here we present XPS data to complement the previously published TPD, IRAS and reactivity studies to elucidate the electronic structure of the system in some detail. The second case study provides additional information on Au nano-particles supported on ultrathin MgO(100)/Ag(100) films where we had observed a specific activity of the particles rim at the metal-oxide interface with respect to CO₂ activation and oxalate formation, obviously connected to electron transfer through the MgO film from the metal substrate underneath. Here we present XPS and Auger data which allow a detailed analysis of the observed chemical shifts. This analysis corroborates previous findings deduced via STM.