Classical description of laser-induced desorption rates

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Abstract
We investigate the effect of a laser on the rate of desorption of an atom from a surface using a classical model. The laser gives rise to an oscillating local electric field which couples to the effective dipole moment created by the interaction between the adatom and the surface. Using analytical procedures, we obtain a single-particle Langevin equation to describe the system. The Langevin equation gives rise to a Fokker-Planck equation governing the probability distribution of the adatom’s velocity and position. In the absence of an electric field, this equation, along with an equilibrium assumption, yields the standard Arrhenius form for the desorption rate. The validity of the equilibrium assumption is discussed in both the absence and the presence of an electric field. By numerically integrating the Langevin equation, we investigate the effects of the laser on specific model systems, and we find that in certain regimes the effect of the laser can be represented by an increased effective temperature of the heat bath. Nonthermal behavior on short time scales is discussed.

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