Adsorption of CO on rutile (1x1)-TiO2(110):: a molecular beam study

Presented are initial, S-0, and coverage dependent, S(Theta), adsorption probability measurements, respectively, of CO on the rutile (1 x 1)-TiO2(1 1 0) surface obtained along both high symmetry azimuth directions (i.e. along the [1 (1) over bar 0] and [0 0 1] azimuth) and parametric in the impact energy, E-i; the angle of incidence, alpha(i); and the surface temperature, T-s. Whereas along the [0 0 1] azimuth approximately a Kisliuk shape of S(Theta) has been observed, for glancing alpha(i) and E-i greater than or equal to 0.52 eV a turnover from the Kisliuk shape of S(Theta) to an auto-catalytic adsorption (increase in S with Theta) could be detected along the [1 (1) over bar 0] direction. Along both azimuth directions S-0 obeys for E-i greater than or equal to 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. (C) 2003 Elsevier B.V. All rights reserved.