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 layer-by-layer growth occurs, i.e. which constitute wetting systems. Theoretical modelling using forced-oscillator calculations with a minimum of free parameters was able to reproduce the initial sticking coefficients, so, and their dependence on gas temperature using essentially one free parameter; in particular the strong quantum effect of zero phonon scattering can be well understood in this model. As further tests we have measured the so-values of the same gases on slightly (H-covered Ru(001); Pt(111)) and strongly (K-mono- and multilayers on nu(001)) modified surfaces. Tn particular the latter systems constitute sensitive tests of the model, since here the interaction energies of the rare 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 constitute nonwetting systems. Our model is able to explain the results even for such strongly varying interaction parameters qualitatively and, where fully applicable, quantitatively.