surface excess concentration (at an interface), Γ

A quantity defined by

$Γ i = n i σ A s$

where $n i σ$ is the surface excess (or adsorption) of component $i$ and $A s$ is the area of the dividing surface or interface.

Source:

PAC, 1986, 58, 967 (Reporting data on adsorption from solution at the solid/solution interface (Recommendations 1986)) on page 970