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O: Fachverband Oberflächenphysik

O 55: Poster Session III - MA 141/144 (Methods: Atomic and Electronic Structure; Particles and Clusters; Heterogeneous Catalysis; Semiconductor Substrates: Epitaxy and Growth+Adsorption+Clean Surfaces+Solid-Liquid Interfaces; Oxides and Insulators: Solid-Liquid Interfaces+Epitaxy and Growth; Phase Transitions; Metal Substrates: Adsorption of Inorganic Molecules+Epitaxy and Growth; Surface Chemical Reactions; Bimetallic Nanosystems: Tuning Physical and Chemical Properties; Oxides and insulators: Adsorption; Organic, polymeric, biomolecular films; etc.)

O 55.59: Poster

Mittwoch, 27. Februar 2008, 18:30–19:30, Poster F

The growth and structure of titania films on a rhenium(0001) surface — •Susanne Schubert and Klaus Christmann — Institut für Chemie und Biochemie der FU Berlin, Germany

In view of the significance of titanium dioxide as a catalyst support for low-temperature CO oxidation we have studied the epitaxy and chemical properties of titanium dioxide films grown on a clean and oxygen-covered Re(0001) surface. Titania films were prepared by co-deposition of Ti vapor in an oxygen atmosphere at elevated temperatures (T≥830K). The structure and chemical (surface) composition of these films were analyzed by means of low-energy electron diffraction (LEED), low-energy ion scattering (LEIS) and X-ray photoelectron spectroscopy (XPS) as a function of deposition rate and film thickness starting from the monolayer regime up to concentrations of 10 to 40 monolayers. While the overall film stoichiometry is close to TiO₂ (rutile) independent of film thickness we find a moiré LEED pattern at low surface concentrations, faceting with hexagonal phases in three domains of rutile(110) rotated by 120^∘ against each other in the medium coverage regime, and well-ordered unfaceted rutile films for thicknesses beyond ≈ 40 monolayers. The respective growth behavior can be described by a Stranski-Krastanov mechanism.