CHARACTERIZATION OF BANDGAP STATES IN V-DOPED TIO2 BY HIGH-RESOLUTION X-RAY PHOTOEMISSION SPECTROSCOPY

Core- and valence-level photoemission spectra of V-doped TiO2 have been measured with monochromatic Al-K alpha X-ray excitation. UHV annealing of as-presented samples leads to the appearance of a photoemission peak above the O 2p valence band within the bulk bandgap of TiO2. Simultaneous changes in V core-level spectra allow this peak to be identified as arising from electrons trapped on vanadium ions to generate localised V-IV centres.