Thermally activated reconstruction of TiO2(110)-(1×1) surface in the presence of potassium: An STM study

Abstract: The deposition of potassium onto TiO2(110) surface at 330K and the effects of post-annealing are investigated by scanning tunneling microscopy (STM), thermal desorption spectroscopy (TDS) and Auger-electron spectroscopy (AES). At lower K coverages (a few percentage of a monolayer), 3–4nm long and 1–2nm wide islands appear which can be identified with K covered regions. At higher K coverages, the surface exhibits disordered structures. Depending on the initial K coverage, the annealing above 700K in UHV results in ordering of the surface. For app. 1/3 monolayer K and annealing at around 900K, the entire surface reconstructs into a (1×2) phase accompanied by the appearance of pits with an average diameter of 20–30nm. This morphology is characteristic up to 1000K. Above this temperature, the recovery of the (1×1) phase was observed. At low K coverages (<0.2ML) the annealing at 1000K resulted in the formation of protruding islands of approximately 2×2nm2 which were identified with a strongly bonded surface compound containing K. [Copyright &y& Elsevier]