Ultrathin TiO2 Films on (1x2)-Pt(110): a LEED, Photoemission, STM, and Theoretical Investigation

The preparation and characterization of fully oxidized TiO2 ultrathin films obtained by reactive deposition of Ti in an O2 background on the (1×2)-Pt(110) reconstructed surface is described in details. The structure, the electronic properties, and the morphology of the epitaxial films giving rise to a (14×4) coincidence superstructure are discussed on the basis of low-energy electron diffraction, photoemission (both core and valence band), angle-scanned X-ray photoelectron diffraction, scanning tunneling microscopy data, and density functional theory calculations. We show that the oxide overlayer is a stoichiometric lepidocrocite-like single-domain nanosheet. This can be thought of as originating from a (100) oriented anatase bilayer which spontaneously restructure by a uniaxial relative sliding of one single layer with respect to the other by half a unit cell. According to the results of theoretical calculations, the process is self-driven by the spatial confinement, whereas a minor role is played by the interaction with the substrate. The occurrence of the (14×4) coincidence between the overlayer and the substrate is fully rationalized on the basis of the reported data.