Point tension in adsorption at a chemically inhomogeneous substrate in two dimensions

الأصل · EN

We study adsorption of liquid at a one-dimensional substrate composed of a single chemical inhomogeneity of width 2L placed on an otherwise homogeneous, planar, solid surface. The excess point free energy η(L,T) associated with the adsorbed layer's inhomogeneity induced by the substrate's chemical structure is calculated within exact continuum transfer-matrix approach. It is shown that the way η(L,T) varies with L depends sensitively on the temperature regime. It exhibits logarithmic divergence as a function of L in the limit L→∞ for temperatures such that the chemical inhomogeneity is completely wetted by the liquid. In the opposite case η(L,T) converges for large L to 2η₀, where η₀ is the corresponding point tension, and the dominant L-dependent correction to 2η₀ decays exponentially. The interaction between the liquid layer inhomogeneities at -L and L for the two temperature regimes is discussed and compared to earlier mean-field theory predictions.