When the area of the @I03082@ between two phases is proportional to the mass of one of the phases (e.g. for a solid @A00153@, for an @E02065@ or for an @A00176@), the specific surface area (\(a\),\(s\) or preferably \(a_{s}\)) is defined as the surface area divided by the mass of the relevant phase.
Green Book, 2nd ed., p. 63 [Terms] [Book]
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 583 [Terms] [Paper]