Ionicity of metallic oxide surfaces on metals as observed by Auger (XPS) spectroscopy

Research relevant to the understanding of polymer–metal adhesion led us to an oxygen Auger (KLL) study on metal oxide surfaces. This was done in order to analyse the ionicity and strength of ‘Lewis sites’ on oxide surfaces grown on metals as compared to their bulk metal oxide counterparts. Following some suggestions contained in earlier works by Wagner we show that relative Auger (KLL) oxygen energies are a sensitive probe of oxygen valence electron population and hole relaxation. A semi‐empirical model is discussed to justify these findings. Furthermore it is shown that this ‘observable’ feature is also influenced by the metal oxide thickness at the metal surface.