Interaction of H2, CO and O2 with a vanadium (111) surface

Adsorption of hydrogen and deuterium on V(111) is governed by dynamical steering at low molecular energies whereas at high beam energies direct adsorption is observed. Strong rotational effects and clear isotope effects in the adsorption dynamics of H-2 and D-2 can be seen. At elevated surface temperatures hydrogen dissolves in the bulk; the absorption coefficient is strongly dependent on surface temperature. For CO a large fraction dissociates upon adsorption. At the clean surface an intrinsic precursor facilitates adsorption and at finite coverages an extrinsic precursor leads to a sticking coefficient independent of coverage. Oxygen can adsorb up to a saturation coverage of 3.8 monolayers followed by surface oxidation. For all three gases calibration procedures for surface coverages are presented as well as quantitative values for the sticking coefficients. (C) 2000 Elsevier Science B.V. All rights reserved.