ISLAND MEDIATED STICKING OF THE RARE-GASES ON CU(110)

The sticking of Ar, Kr, and Xe on the Cu(110) surface is investigated by He-atom scattering. For all three rare gas species the sticking coefficient is strongly coverage dependent. It first increases with coverage and decreases again towards monolayer completion. This behavior is explained by the formation and coalescence of 2D rare gas islands during adsorption. Surprisingly, the trapping efficiency of these islands is larger than expected from their actual geometric size. This is interpreted in terms of a highly mobile transient state of the rare gas atoms impinging on the bare Cu(110) surface.