The growth and structure of titanium dioxide films on a Re 10 10 surface Rutile 011 2x1

Titanium dioxid films were grown on Re 10 10 by Ti vapor deposition in oxygen at T 830 K and studied by means of low energy electron diffraction LEED , X ray photoelectron spectroscopy XPS , low energy ion scattering LEIS and X ray diffraction XRD . The Ti oxid stoichiometry was determined by XPS as Ti O 1 2, with the Ti oxidation state 4 . The TiO2 growth was monitored by means of LEED as a function of film thickness. Extending the coverage from the submonolayer into the multilayer regime gives rise to a p 2x2 pattern, a poorly ordered 1x1 , and, finally, a stable 2x2 structure, the latter being associated with a homogeneous TiO2 phase. For normal electron incidence, the 2x2 LEED pattern exibits systematically extinguished beams at n 1 2,0 positions, indicating a glide mirror plane. The pg 2x2 structure could be explained by both a rutile 011 2x1 reconstructed surface and a bulk truncated brookite 001 surface. Faceting phenomena, i.e. running LEED spots, observed with thin TiO2 films point to the formation of a rutile 011 2x1 surface with two domains and 011 2x1 facets and rule out the brookite alternative. Confirmation of this assignment was obtained by an XRD analysis perfomed at the Berlin synchrotron facility BESS