Multilayer adsorption of xenon and argon on graphite: Wetting behaviour

New multilayer adsorption isotherms of Xe and Ar on graphite (0001) are presented. For the particular case of the 5th Xe layer we show the interest of differential pressure measurements, which allow a much more reliable assessment of the wetting behaviour than absolute measurements. We show that earlier claims of incomplete wetting of graphite by crystalline Ar or Xe are by no means warranted. We recall that capillary condensation is often a problem in multilayer adsorption studies and that a careful examination of layering transitions can be particularly useful.