Wetting properties of rare gases on weak substrates

Since the original prediction that liquid He does not wet Cs at low temperatures and the soon after experimental observation of a wetting transition on this system, noble gases on alkalis have become model systems for the study of wetting transitions and of their accompanying line of prewetting transitions off coexistence. Here we review very briefly the theory of wetting and prewetting and discuss some results on the properties of rare gases adsorbed on alkali surfaces obtained with the use of the density functional theory and of accurate adsorbate-substrate potentials.