A 2-dimensional lattice gas with interaction-dependent rates of particle diffusion and desorption was studied by using Monte Carlo methods to reproduce the decay of harmonic perturbations of the profile. When close to equilibrium, the long-wavelength limit dynamics separated into a desorption process which was independent of the perturbation wave vector and was proportional to collective diffusion. In most cases, both processes could be analyzed separately. It was shown that, in some highly-ordered systems - like the (2 x 2) ordered structure of a repulsive square lattice gas - one process could change the characteristics of the other. It was observed that the diffusion coefficient became slower when the desorption process was more rapid. This effect was even more visible at higher temperatures. The measured activation energy of the diffusion process could therefore be changed by rapid desorption and adsorption processes; even when the system was close to equilibrium.

Diffusion and Desorption Processes in Ordered (2 x 2) Lattice Gas Phase. M.A.Załuska-Kotur, A.Lusakowski, S.Krukowski, L.A.Turski: Surface Science, 2002, 507-510, 150-4