Initial Formation of Positively Charged Gold on MgO(001) Thin Films: Identification by Experiment and Structural Assignment by Theory

Infrared spectroscopy experiments using CO as a probe and X-rayphotoelectron spectroscopy were used to study the initial nucleation of gold on the surface of MgO(001)/Ag(001) thin films at 90 K. The most intense CO infrared signal observed at low gold coverage was at 2154 cm(-1), indicating the formation of positively charged Au species. Both infrared and photoemission data reveal details about the thermally induced sinter behavior of metallic and positively charged gold species on the MgO(001) surface. Density functional theory was used to examine different defect types on the MgO surface for their ability to form positively charged Au species and to assign the observed sites on the MgO(001) surface for their ability to form positively charged Au species and to assign the observed R stretch vibration to Au-n(+)-CO species on specific binding sites on the MgO(001) surface.