Vibrational Energy Transfer at Gas–Solid Interfaces

Abstract

Linear semiclassical vibrational energy‐transfer theory is applied to the interaction of vibrationally excited CO₂, N₂O and CH₄ with solid NaCl and of N₂ with glass. The model shows energy transfer to be slow during specular reflection but fast when the molecules are adsorbed and migrating over the surface. Values for the condensation coefficients are derived from the experimental energy‐transfer probabilities, yielding 0.22, 0.37, and 0.88–1.0, for CO₂, N₂O, and CH₄ on NaCl, respectively. The theory substantiates existing evidence that CH₄ rotates freely about at least one axis on a NaCl surface, and suggests that this rotation is involved in the vibrational energy degradation. Vibrationally excited N₂ on glass is deactivated mainly through interaction with surface OH groups.