A kinetic model for gas adsorption at solid surfaces by surface transient formation

In this paper is presented a model for the kinetics of gas adsorption at solid surfaces, in which transient formation is involved. In the case of ideal adsorption where the rate constants are independent of the surface coverages, the kinetics can be solved exactly in the framework of the first order kinetic law. The expression of the sticking coefficient for the final chemisorbed state is obtained in terms of the rate constants introduced in the model and compared to the expression commonly adopted in the literature. By means of a fitting procedure the kinetics were used to describe experimental data on the dioxygen adsorption at the Zn(0001) surface. An appropriate analysis of the fitting parameters, derived from adsorption data collected at different temperature of the substrate, allows for the activation energy of the processsurface transient final adsorbed species to be estimated.