Atom trapping on surfaces

Abstract

The trapping of gas atoms on collision with a solid surface is described using the soft cube model. Fraction trapped is defined as that fraction of an incident flux which has a normal energy less than the gas surface potential well depth, after a single collision with the surface. Sticking coefficient is synonymous with fraction trapped. The functional dependence of the sticking coefficient on the gas and surface atom masses, temperatures and the interaction potential parameters is obtained. Sticking coefficients are predicted over a wide temperature range for xenon, argon, and neon on gold, silver, and platinum, and also for cadmium, gallium, titanium, cesium, silver, and rubidium on tungsten. Good agreement is obtained with experimental results for xenon on tungsten, platinum, and silver and for silver on tungsten. Argon and krypton on tungsten, platinum, and silver obtain reasonable agreement. Potential parameters for xenon, krypton, and argon on tungsten, platinum, and silver are derived from comparison with sticking coefficient data. These parameters are analogous to the gas‐gas potential parameters obtained from gas phase transport properties, and though more approximate, may eventually prove to be as useful.