Adsorption of CO on rutile (1 × 1)-TiO2(1 1 0): a molecular beam study

Presented are initial, S0, and coverage dependent, S(Θ), adsorption probability measurements, respectively, of CO on the rutile (1 × 1)-TiO2(1 1 0) surface obtained along both high symmetry azimuth directions (i.e. along the [1 1̄ 0] and [0 0 1] azimuth) and parametric in the impact energy, Ei; the angle of incidence, αi; and the surface temperature, Ts. Whereas along the [0 0 1] azimuth approximately a Kisliuk shape of S(Θ) has been observed, for glancing αi and Ei⩾0.52 eV a turnover from the Kisliuk shape of S(Θ) to an auto-catalytic adsorption (increase in S with Θ) could be detected along the [1 1̄ 0] direction. Along both azimuth directions S0 obeys for Ei⩾0.52 eV normal energy scaling and below that impact energy total energy scaling. The effect of an intrinsic precursor state is tentatively concluded. A decrease in the heat of adsorption with coverage indicates repulsive lateral interactions of the CO.