Adsorption in noninterconnected pores open at one or at both ends: a reconsideration of the origin of the hysteresis phenomenon.

We report on an experimental study of adsorption isotherm of nitrogen onto porous silicon with noninterconnected pores open at one or at both ends in order to check for the first time the old (1938) but always current idea based on Cohan's description which suggests that the adsorption of gas should occur reversibly in the first case and irreversibly in the second one. Hysteresis loops, the shape of which is usually associated with interconnections in porous media, are observed whether the pores are open at one or at both ends, in contradiction with Cohan's model.