Random sequential adsorption of polyatomic species with the presence of impurities

Random sequential adsorption of k-mers (particles occupying k adsorption sites on the substrate) of different sizes and shapes deposited on square lattices is studied. Heterogeneous surfaces caused by impurities previously and randomly deposited are considered. Thus, an adsorption site occupied by an impurity is considered as forbidden for the deposition of adsorbent. As a consequence, the average coordination number for each available element depends on the concentration of impurities. For discrete models, at the late stage the surface coverage evolves according to θ(t)=θ(∞)−Aexp[−tσ], where θ(∞) is the jamming coverage while A and σ are fitting parameters. The dependence of the terminal relaxation time σ (which determines how fast the lattice is filled up to the jamming coverage) on the parameters of the problem is established.