One‐Phonon Inelastic Scattering of Gas Atoms in Three Dimensions by a Simplified Continuum Model of a Solid: Calculation of Energy Accommodation Coefficients

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Abstract
The quantum‐mechanical theory of the one‐phonon inelastic scattering of gas atoms in three dimensions by a solid surface, presented recently by F. O. Goodman [Surface Sci. 30, 1 (1972)] is used to calculate energy accommodation coefficients for the system He‐W. The approximations used are the same as those in the above paper, except that the gas‐surface interaction is represented by the exponential repulsive potential with zero well‐depth. The theory is compared with experimental data on both equilibrium and nonequilibrium energy accommodation coefficients for He‐W. With a gas‐surface interaction potential inverse‐length parameter corresponding to a Morse parameter for He‐W in the range 1.3–1.6 Å−1, and with a (bulk) Debye temperature for W in the range 320–380°K quantitative agreement is found between theory and experiment in regimes in which the theory may be expected to be applicable. These regimes are those in which effects of bound states of gas atoms at the surface, which are neglected in the theory, are relatively unimportant.