Characterization of ultra-thin TiO2 films grown on Mo(112)

Ultra-thin TiO2 films were grown on a Mo(112) substrate by stepwise vapor depositing of Ti onto the sample surface followed by oxidation at 850 K. X-ray photoelectron spectroscopy showed that the Ti 2p peak position shifts from lower to higher binding energy with an increase in the Ti coverage from subto multilayer. The Ti 2p peak of a TiO2 film with more than a monolayer coverage can be resolved into two peaks, one at 458.1 eV corresponding to the first layer, where Ti atoms bind to the substrate Mo atoms through Ti–O–Mo linkages, and a second feature at 458.8 eV corresponding to multilayer TiO2 where the Ti atoms are connected via Ti–O–Ti linkages. Based on these assignments, the single Ti 2p3/2 peak at 455.75 eV observed for the Mo(112)–(8×2)–TiOx monolayer film can be assigned to Ti , consistent with our previous results obtained with high-resolution electron energy loss spectroscopy. © 2006 Elsevier B.V. All rights reserved.