Stepwise isotherms and phase transitions in physisorbed films

Abstract

The present paper outlines the evolution during the last thirty years of research in the field of physisorption of gases on solids with a homogeneous surface. It relates this evolution as lived by some researchers of a physical chemistry laboratory whose objective was not originally to study physisorption as such, but to use it as a method to determine the specific surface area of solids participating in gas reactions. Consequently, the aim is not to give a complete review even of only those results obtained from adsorption isotherms, but simply to recall the way which led to the discovery of several of the most typical adsorption phenomena, i.e.: “gas-liquid-solid” and “commensurate-incommensurate” 2D transitions, 2D polymorphism, wetting transitions and specific behaviour of mixed films.