Capillary condensation, invasion percolation, hysteresis, and discrete memory.

A model of the capillary condensation process, i.e., of adsorption-desorption isotherms, having only porepore interactions is constructed. The model yields ~1! hysteretic isotherms, ~2! invasion percolation on desorption, and ~3! hysteresis with discrete memory for interior chemical potential loops. All of these features are seen in experiment. The model is compared to a model with no pore-pore interactions ~the Preisach model! and to a related model of interacting pore systems ~the random field Ising model!. The capillary condensation model differs from both. @S0163-1829~96!06725-2#