work of cohesion per unit area

https://doi.org/10.1351/goldbook.W06688
Of a single pure liquid or solid phase α, w C α is the work done on the system when a column α of unit area is split, reversibly, normal to the axis of the column to form two new surfaces each of unit area in contact with the equilibrium gas phase. $w_{\text{C}}^{\unicode[Times]{x3B1} }=2\ \gamma ^{\unicode[Times]{x3B1} }$ where γ α is the surface tension between phase and its equilibrium vapour or a dilute gas phase.
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 597 (https://doi.org/10.1351/pac197231040577)