reduced adsorption

Of component $i$ , defined by the equation

$Γ i n = Γ i σ − Γ i c i α − c i β c α − c β$

where $Γ σ$ , $c α$ and $c β$ are, respectively, the total Gibbs surface concentration and the total concentrations in the bulk phases α and β:

$Γ σ = ∑ i Γ i σ$

$c α = ∑ i c i α$

$c β = ∑ i c i β$

The reduced adsorption is invariant to the location of the Gibbs surface. Alternatively, the reduced adsorption may be regarded as the Gibbs surface concentration of $i$ when the Gibbs surface is chosen so that $Γ σ$ is zero, i.e. the Gibbs surface is chosen so that the reference system has not only the same volume, but also contains the same total amount of substance( $n$ ) as the real system.

Source:

PAC, 1972, 31, 577 (Manual of Symbols and Terminology for Physicochemical Quantities and Units, Appendix II: Definitions, Terminology and Symbols in Colloid and Surface Chemistry) on page 591