Thermal desorption induced by chemical reaction on dust surface

Abstract

We propose a new mechanism of desorption of molecules from dust surface heated by exothermic reactions and derive a formula for the desorption probability. This theory includes no parameter that is physically ambiguous. It can predict the desorption probabilities not only for one-product reactions but also for multiproduct reactions. Furthermore, it can predict desorption probability of a pre-adsorbed molecule induced by a reaction at a nearby site. This characteristic will be helpful to verify the theory by the experiments which involve complex reaction networks. We develop a quantitative method of comparing the predicted desorption probability with the experiments. This method is also applied to the theories proposed so far. It is shown that each of them reproduces the experiments with similar precision, although the amount of systematic experimental data that give definite desorption probability are limited at present. We point out the importance of clarifying the nature of the substrate used in the experiment, in particular, its thermal diffusivity. We show a way to estimate the substrate properties from systematic desorption experiments without their direct measurements.