Diffusion Theory for Adsorption and Desorption of Gas Atoms at Surfaces
MASSACHUSETTS INST OF TECH CAMBRIDGE FLUID DYNAMICS RESEARCH LAB
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The time evolution of a nonequilibrium ensemble of gas atoms adsorbed on a solid surface is described. Adsorption and desorption rate constants and adatom adsorbed atom energy distributions are obtained in the steady state approximation from the appropriate master equation or an equivalent diffusion equation. Energy transition probabilities are obtain from a classical gas- surface collision model using an interaction potential composed of an oscillating harmonic repulsion and a stationary attraction. Applications include prediction of adsorption and desorption rate constants, sticking and accommodation coefficients, sublimation and condensation rates, and boundary conditions for the Knudsen layer.
- Physical Chemistry