NONWETTING AND STICKING OF THE HEAVY RARE-GASES ON POTASSIUM SURFACES

We have investigated the adsorption, growth, and desorption of Ar, Kr, and Xe on K mono- and multilayers on Ru(001) at 6.5 K. In all cases, three-dimensional growth from very low rare gas (RG) coverages on, cle arly indicates nonwetting, and the desorption energies for low RG cove rages are much lower than the RG sublimation energies, and lower on K multi- than on K monolayers. Nevertheless, initial sticking coefficien ts of the RG on both types of K layers are well defined and not domina ted by nucleation or by impurities or defects. Their values and depend ence on type of substrate can be understood qualitatively, and quantit atively for Ar in terms of a recently developed quantum mechanical mod el, extending adsorption dynamics studies to nonwetting systems.