surface excess entropy

Defined by:

$S σ = S − S α − S β = S − V α S m α V m α − V β S m β V m β$

( $S m α V m α$ ) and ( $S m β V m β$ ) are the entropy densities in the two bulk phases, where $S m α$ and $S m β$ are the mean molar entropies and $V m α$ and $V m β$ are the mean molar volumes of the two phases.

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 599