Enhanced saturation coverages in adsorption-desorption processes

Many experimental studies of protein deposition on solid surfaces involve a lternating adsorption/desorption steps. In this paper, we investigate the e ffect of a desorption step (separating two adsorption steps) on the kinetic s, the adsorbed-layer structure, and the saturation density. Our theoretica l approach involves a density expansion of the pair distribution function a nd an application of an interpolation formula to estimate the saturation de nsity as a function of the density at which the desorption process commence s, rho(1), and the density of the depleted configuration, rho(2). The theor y predicts an enhancement of the saturation density compared with that of a simple, uninterrupted random sequential adsorption (RSA) process and a max imum in the saturation density when rho(2)=(2/3)rho(1). The theoretical res ults are in qualitative and semiquantitative agreement with the results of numerical simulations. (C) 2000 American Institute of Physics. [S0021-9606( 00)70103-6].