A Monte Carlo study of adsorbed solutions on solid surfaces

We present results of an investigation of the properties of adsorbed solutions formed by gases on solid surfaces, via Monte Carlo computer simulations. The adsorbed solutions are treated as two dimensional fluid mixtures in the presence of an external field which models the structure of the (111) face of an f.c.c. crystal. The same solutions have also been studied in the absence of the external field in order to show the role of the surface structure upon the adsorption equilibrium. The adsorption isotherms were calculated using the potential distribution method and the structure of the adsorbed solutions has been studied through calculations of the singlet and pair distribution functions. Three different mixtures have been considered and the results have been used to describe how differences in molecular size and strength of attractive interactions determine the distribution of components in the mixture between the bulk and adsorbed phases.