Adsorption isotherms and surface geometry

We consider fluids adsorbed at generalised wedges described by shape functi ons x(gamma) in one direction (x), and translationally invariant in the oth er. For the limiting cases gamma = 0 and infinity, the substrate correspond s to a planar wall and a capillary slit, respectively. In this way, we show how wetting-like adsorption isotherms become capillary-like as gamma is in creased from 0 to infinity. The mechanism for the cross-over to condensatio n is shown to involve several intermediate regimes corresponding to novel e xamples of adsorption isotherms. (C) 2001 Elsevier Science B.V. All rights reserved.