Thermodynamic expressions for the Tolman length.
The Tolman length delta [TolmanJ. Chem. Phys. 17, 333 (1949)] measures the extent by which the surface tension of a small liquid drop deviates from its planar value. Despite increasing theoretical attention, debate continues on even the sign of Tolman's length for simple liquids. Recent thermodynamic treatments have proposed a relation between the Tolman length and the isothermal compressibility of the liquid at two-phase coexistence, delta approximately -kappa([script-l])sigma. Here, we review the derivation of this relation and show how it is related to earlier thermodynamic expressions. Its applicability is discussed in the context of the squared-gradient model for the liquid-vapor interface. It is found that the relation is semiquantitatively correct for this model unless one is too close to the critical point.
Colloid and Interface Science, Leiden Institute of Chemistry, Gorlaeus Laboratories, The Netherlands. e.blokhuis@chem.leidenuniv.nl
Edgar M
EM
Blokhuis
Joris
J
Kuipers