Coverage dependence of the dynamics of ethylene adsorption on Ag(210)

The sticking probability of C2H4 on Ag(210) is studied by the molecular beam technique and by high resolution electron energy loss spectroscopy. At a crystal temperature of 110 K, adsorption occurs initially into a stable, pi-bonded, state. At larger coverage a metastable state is populated, too. The sticking probability, S, decreases with increasing translational energy indicating non-activated adsorption. At low coverage and for impact angles from -60degrees to +60degrees, S is angle independent, decreasing only as soon as the (100) nanofacets start to be shadowed. At higher coverage, in contrast, S depends on the impact angle, decreasing markedly for grazing incidence onto the (100) nanoterraces. The saturation coverage corresponds to quarter occupancy of the available step sites