Adsorption–desorption processes of extended objects on a square lattice

Kinetics of adsorption–desorption process is studied by Monte Carlo simulation on a square lattice. The depositing objects are squares covering nine lattice sites. At each Monte Carlo step adsorption is attempted with probability Pa and desorption with probability Pdes=1−Pa. The equilibrium coverage and the relaxation time are obtained for various ratios of the adsorption probability to the desorption probability. The dependence of the relaxation time σ on (Pa/Pdes) is described by a power law σ∝(Pa/Pdes)2. The equilibrium coverage decreases exponentially with Pdes/Pa for low desorption probabilities.