Monte Carlo simulation of adsorption on preadsorbed layers

Monte Carlo simulation results for a simple lattice gas model of multilayer adsorption on preadsorbed layer are presented. The effects of mixing of the preadsorbed gas with the adsorbate as well as of the wetting behavior of preadsorbate on the mechanism of the film development are discussed. It is demonstrated that the mixing properties of the adsorbed and preadsorbed species are responsible for the order of layering transitions. In the case of systems which exhibit phase separation the layering transitions retain the first-order character. On the other hand, when the adsorbate dissolves in the preadsorbed film, the formation of the first layers is a continuous process. It is also shown that the wetting behavior of preadsorbed gas considerably influences the mechanism of the adsorbate layer formation.