ON THE INFLUENCE OF SURFACE-TEMPERATURE ON ADSORPTION AND DESORPTION IN THE D2/CU(111) SYSTEM

We have used the principle of detailed balance to relate measurements on the adsorption of D2 on Cu(111) to the desorption dynamics of this system. Calculations of desorption characteristics based on the dependence of the adsorption probability on incidence energy and angle measured at a surface temperature of 120 K are not in perfect agreement with observations. In fact, we find that desorption measurements made over a range of surface temperatures cannot be adequately accounted for by any single function of the sticking probability on the incidence energy and angle. Rather, it is found necessary to allow this function to vary slightly with surface temperature. The resulting temperature dependent sticking function is consistent with the angular distributions of D2 desorbing from Cu(111) at 370, 600 and 800 K, with adsorption measurements made at 120 K, and with the dependence of the mean kinetic energy on desorption angle at 1000 K We show that the deduced temperature dependence of the adsorption probability can be partially accounted for by allowing for the effect on the collision energy of the Boltzmann distribution of surface atom motions.