Critical points on vapor-liquid stratification curves in inhomogeneous systems

Stratification of molecules in inhomogeneous systems can cause the appearance of multiplicity of critical points on vapor-liquid stratification curves. Such systems are open inhomogeneous surfaces and porous solids. The adsorption of molecules on them is determined by the joint action of the surface potential and intermolecular interactions. The joint influence of these potentials forms subregions of the system as a whole in which first-order phase transitions occur. The number and parameters of critical points depend on the composition and structure of inhomogeneous systems. The largest possible number of critical points is related to the presence of macroscopic regions of various types. If regions comprising adsorption centers of various types have locally ordered structures, the system contains one critical point with modified critical parameters, similarly to homogeneous systems. If the influence of the surface potential prevails over intermolecular interaction, the system does not contain critical points.