An Adsorption Equation for an Ultrathin Fluid Film

Henry's law is found by applying the condition of extremum to the Gibbs function of a fluid film. The resulting equation relates linearly the thickness of the adsorbed layer to the external gas pressure. The equation reveals that the coefficient of proportionality beta depends inversely on the saturation pressure p0. It also shows that wetting effects are irrelevant. These results predicted by the present model are in agreement with experiment. Copyright 1998 Academic Press.