STICKING OF RARE-GAS ATOMS IN WETTING AND NONWETTING SYSTEMS

In earlier work we have investigated the sticking of the rare gases Ne to Xe on a typical flat transition metal surface, Ru(001), on which l ayer-by-layer growth occurs, i.e. which constitute wetting systems. Th eoretical modelling using forced-oscillator calculations with a minimu m of free parameters was able to reproduce the initial sticking coeffi cients, so, and their dependence on gas temperature using essentially one free parameter; in particular the strong quantum effect of zero ph onon scattering can be well understood in this model. As further tests we have measured the so-values of the same gases on slightly (H-cover ed Ru(001); Pt(111)) and strongly (K-mono- and multilayers on nu(001)) modified surfaces. Tn particular the latter systems constitute sensit ive tests of the model, since here the interaction energies of the rar e gases with the surface are smaller than those on their own solid, so that 3D island growth occurs from very low coverages on; i.e., they c onstitute nonwetting systems. Our model is able to explain the results even for such strongly varying interaction parameters qualitatively a nd, where fully applicable, quantitatively.