Dynamics of Ethene Adsorption on Clean and C-Contaminated Cu(410)

As recently established (J. Am. Chem. Soc. 2008, 130, 12552), ethene adsorption on Cu(410) occurs both molecularly and dissociatively, the latter resulting in carbon contamination of the surface. Here we report on the coverage-dependent dynamics of C2H4 adsorption on clean and carbon-contaminated Cu(410). For the bare surface, the initial sticking probability has a very weak dependence on kinetic energy and is almost independent of angle of incidence. Molecular adsorption is in both cases precursor-mediated and nonactivated. Ethene dissociation takes place during adsorption as well as upon annealing. Both paths proceed via a molecular precursor. The former is translationally activated, while the latter depends strongly on the heating rate. The presence of preadsorbed carbon, resulting from previous uptakes, affects both the sticking probability and the attained saturation coverage. The latter quantity is shown to be a sensitive probe of carbon precoverage. A scheme of the complicated potential energy surface of this system is derived and discussed.