Adsorption Thermodynamics of Monomers on Diluted-Bonds Triangular Lattices

M. QUINTANA; P. M. PASINETTI; A. J. RAMIREZ-PASTOR; G. ZGRABLICH

SURFACE SCIENCE

Año: 2006 vol. 600 p. 33 - 42

0039-6028

The surface of amorphous solids cannot be usually represented by a regular lattice of adsorbing sites. One of the main characteristics of such surfaces is a variable connectivity for each site. A simple model consisting of a triangular lattice where a fraction of bonds (interactions) is suppressed at random is used here to find out, by using Monte Carlo simulations, how the adsorption thermodynamics of repulsively interacting monomers is modified with respect to the same process in the regular lattice. Adsorption isotherm, differential heat of adsorption and adsorbed phase entropy calculations are carried out showing and interpreting the effects of the variable connectivity. In particular, it is found that the order–disorder phase transition observed for the regular lattice survives, though with modifications, above a critical mean connectivity.