Role of the Attractive Potential in Gas—Surface Interaction Theory

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Abstract
To study quantum mechanically the role of the attractive potential in gas—surface interaction theory, a one‐dimensional ``oscillating repulsive wall'' model is presented. Results are obtained for a rather general form of the attractive potential by combining a WKB method with a distorted‐wave Born approximation and the one‐phonon approximation; the analysis is restricted to monatomic gas molecules. Discussions of the validity of the method lead to the expectation, or at least to the hope, that it may give a reasonably realistic description of some gas—surface interactions. It is concluded that considerable care should be taken when gas—surface interaction potentials which incorporate long‐range exponential attractive behavior (such as the commonly used Morse potential) are used in discussions of low‐energy interactions, when transitions of gas molecules into their bound states at the surface may play important roles. An example of the results is given in the form of an approximate calculation of the adsorption probability of a low‐energy gas molecule by a cold surface.