| Abstract
| - A model system of alumina-supported vanadia particles, representing catalysts of the type oxide1/oxide2, wasprepared under ultrahigh vacuum (UHV) conditions and characterized regarding its structural and electronicproperties. As supporting oxide we used a thin, well-ordered alumina film grown on NiAl(110), which allowsthe application of scanning tunneling microscopy (STM), infrared reflection−absorption spectroscopy (IRAS),and X-ray photoelectron spectroscopy (XPS) without charging effects. Vanadium oxide particles were preparedvia metal evaporation in an oxygen ambient, leading to the growth of small, roundish oxide particles withvanadium in the +3 oxidation state. The particles are shown to interact strongly with the alumina support,resulting in an increased alumina film thickness and a distortion of the alumina film structure. IR absorptionsignals of the deposits could be successfully assigned to specific V-containing species, thus providing insightinto the inner structure of the particles. The species identified are surface-localized vanadyl groups (VO),interface-localized vibrations involving V, O, and Al ions, and lattice structures typical of bulk V2O3.
|
