Desorption kinetics from disordered surfaces

We present a computational study on the kinetics of desorption from disordered surfaces, both energetically homogeneous and energetically heterogeneous. When gas molecules adsorb onto struc- turally amorphous surfaces the extraction of Arrhenius parameters from experimental data becomes more difficult. By using a kinetic Monte Carlo algorithm we are able to keep track of the transient variations in the energy of activation and extract the overall preexponential factor. The presence of sites with multiple numbers of nearest neighbors result in various desorption rates, which has an effect on the preexponential factor, in addition to a reduction in configurational entropy arising from the fact that not all sites are equally accessible as they would be in an crystalline surface. Adding energetic heterogeneity to the disordered surface accentuates some of these observed effects.