TITANIUM AND REDUCED TITANIA OVERLAYERS ON TITANIUM DIOXIDE(110)

The adsorption of titanium on titanium dioxide TiO2(110) has been stud ied by X-ray photoelectron spectroscopy (XPS) and low energy ion scatt ering (LEIS). The XPS data for Ti overlayers are interpreted using pea k fitting based on experimental standard spectra. 4 Angstrom of Ti dep osited at 150 K reacts with the substrate to produce approximate to 12 Angstrom of intermediate oxidation state Ti. Adsorption of neutral me tal begins on top of this interface oxide film, but 20 Angstrom of dep osited Ti are needed to cover the oxide completely. LEIS data indicate a tendency for clustering of Ti on top of the interface oxide. Ar+ sp uttering of stoichiometric TiO2 leads to preferential loss of O from t he near surface region. This reduction of the clean, annealed oxide su rface by Ar+ ion bombardment starts immediately and does not reach a s teady state until 3 x 10(17) ions cm(-2), at which point the reduced o verlayer is 17 Angstrom thick.