4. Adsorption and segregation models

At constant temperature, variations in surface energy with chemical potential (i.e., volume composition for segregation in the case of ideal solutions, or pressure for adsorption of perfect gases) can be used to determine surface concentration. But these determinations of surface energy variations are tricky to perform, and results are few and far between. Adsorption and segregation models have therefore been developed, enabling surface concentration to be directly related to pressure or volume concentration.

In 4.1 we present the simplest of these models, in which no lateral interactions...