INVERSE PHOTOEMISSION-STUDY OF THE DEFECTIVE TIO2(110) SURFACE

We present inverse photoemission spectroscopy (IPE) data from the nearly perfect and defective TiO2(110) surfaces. In the spectra from the nearly perfect surface, features appearing approximately 1 and approximately 4 eV above the Fermi level are identified as the primarily Ti-derived 2t2g levels and 3e(g) levels. This result is consistent with earlier electronic structure calculations and x-ray absorption studies by other groups. Spectra from the defective TiO2(110) surface exhibit a new feature approximately 3 eV above the Fermi level. This is in agreement with calculations based on defective TiO2(110) surface but has never been observed experimentally before. In contrast to ultraviolet photoemission, IPE spectra from the nearly perfect and ion bombarded TiO2(110) surfaces differ considerably at very low ion doses. IPE spectra from Ti-deposited TiO2(110) surfaces are extremely similar to those from the ion bombarded surface indicating that the spectral changes typical of the defective surface are characteristic of a reduced TiOx phase.