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The Effect of Surface Impurities on the Thermal Accommodation of Rare Gases on a Tungsten Surface

A rather comprehensive experimental examination of the effect of surface impurities (potassium and cesium) on the thermal accommodation of rare gases on a tungsten surface has been made by Roach and Thomas. The present work examines these effects from a theoretical viewpoint with particular emphasis on the effect on the thermal accommodation of helium on a tungsten surface caused by the adsorption of cesium ions and/or atoms. For this examination, the theory of Allen and Feuer has been utilized using reasonable values of the interaction parameters for helium with the adsorbate as well as the force constant for the adsorbate-substrate bond. Resulting values of the accommodation coefficients are compared with experimental values.