A “Dipole–Induced Dipole” Quantum Model and the Effect of an Inert Environment on the Intensity of Infrared Absorption

Abstract

A theory of the imaginary part of isotropic polarizability induced by dipole–dipole interactions between isotropically polarizable particles has been developed on the basis of diagram technique. A classification of single infrared resonances corresponding to the cases of allowed absorption and absorption induced by intermolecular interactions has been proposed. A summation of the diagram contributions describing the change in the intensity of the allowed absorption due to the effect of the reaction field of the environment has been carried out for the dipole–induced dipole (DID) scheme. The strict results obtained in such a way contradict the Onsager–Bettcher model, which is semiempirical. The numerical estimates show that the role of the reaction field in the observed changes in the intensity of the vibrational bands of the simplest model systems (HCl and HBr in inert solvents) is small and decreases with increasing solvent particle size, which indicates the inadequacy of the DID and Onsager–Bettcher models to the experimental data.