Olefin metathesis catalyst .3. Angle-resolved XPS and depth profiling study of a tungsten oxide layer on silica

Model supports consisting of a thin layer of SiO2 on a Silicon single crystal have been used to study the [W](n+)/SiO2/Si (100) model catalyst precursor prepared by a controlled reaction of pi-C5H5W(CO)(3)Cl with the SiO2 surface. Characterization of the tungsten surface species has been performed by combination of conventional, angle-resolved and depth-profiling X-ray photoelectron spectroscopy (XPS). The silica surface consists of highly dispersed W-oxide units linked by two Si-O-W bonds. Further, compared with the powder analogues, a drastic increase in spectral resolution and detailed band structure is observed in the XPS spectra.