Wetting properties of rare gases on weak substrates

Since the original prediction that liquid He does not wet Cs at low tempera tures and the soon after experimental observation of a wetting transition o n this system, noble gases on alkalis have become model systems for the stu dy of wetting transitions and of their accompanying line of prewetting tran sitions off coexistence. Here we review very briefly the theory of wetting and prewetting and discuss some results on the properties of rare gases ads orbed on alkali surfaces obtained with the use of the density functional th eory and of accurate adsorbate-substrate potentials. (C) 2000 Elsevier Scie nce B.V. All rights reserved.