The growth and structure of titanium dioxide films on a Re(10-10) surface: Rutile(011)-(2 x 1)

Titanium dioxide 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 oxide stoichiometry was determined by XPS as Ti:O = 1:2, with the Ti oxidation state (4+). The TiO, 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(2 x 2) pattern, a (poorly ordered) (1 x 1), and, finally, a stable (2 x 2) structure, the latter being associated with a homogeneous TiO, phase. For normal electron incidence, the (2 x 2) LEED pattern exhibits systematically extinguished beams at (N +/- 1/2, 0) positions, indicating a glide mirror plane. The pg(2 x 2) structure could be explained by both a rutile(011)-(2 x 1) reconstructed surface and a bulk truncated brookite(00 1) surface. Faceting phenomena, i.e. running LEED spots, observed with thin TiO, films point to the formation of a rutile(011)-(2 x 1) surface with two domains and {0 1 1} -(2 x 1) facets and rule out the brookite alternative. Confirmation of this assignment was obtained by an XRD analysis performed at the Berlin synchrotron facility BESSY. (c) 2006 Elsevier B.V. All rights reserved.