Adsorption isotherms and surface geometry

We consider fluids adsorbed at generalised wedges described by shape functions xγ in one direction (x), and translationally invariant in the other. For the limiting cases γ=0 and ∞, the substrate corresponds to a planar wall and a capillary slit, respectively. In this way, we show how wetting-like adsorption isotherms become capillary-like as γ is increased from 0 to ∞. The mechanism for the cross-over to condensation is shown to involve several intermediate regimes corresponding to novel examples of adsorption isotherms.