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RESEARCH PRODUCT

Growth Kinetics of Wetting Layers at Surfaces

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Monte Carlo simulation of lattice gas models for the wetting transitions in systems with short range forces are described. A nearest-neighbor simple cubic lattice with nonconserved “Glauber dynamics” is used, applying a slab geometry (LxL cross section). It is shown that the growth proceeds in two stages: for short times t, the thickness of the wetting layer at an initially nonwet wall increases proportional to the logarithm of the time; for t » L2(lnL)2 the thickness increases proportional to t1/2/L. Generalizations to other systems are briefly discussed. Also two-dimensional growth of a wetting film at surface steps is considered, considering “terraces” of an LxM geometry with M»L as substrate for adsorption. The steps may act like a “boundary field” at the adsorbed layer. If this field couples quadratically to the order parameter only, rather than wetting one observes the film to spontaneously break up in a one-dimensional sequence of ordered domains.