surface excess Helmholtz energy

https://doi.org/10.1351/goldbook.S06177
Defined by: $A^{\sigma }=U^{\sigma }- T\ S^{\sigma }$ where $$U^{\sigma }$$ is the @S06173@, $$T$$ is the @T06321@, and $$S^{\sigma }$$ is the @S06175@.
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 [Terms] [Paper]