Critical examination of the herzberg-teller theory

Abstract

It is shown that the Herzberg-Teller (HT) theory for computing the intensity pattern of forbidden transitions is not generally valid. For forbidden transitions, the standard computation of changes of equilibrium configurations which makes use of the Franck-Condon overlap factors is thus not adequate, in general. It is shown that the HT and non-HT induced transition moments are usually of comparable magnitude. Interference effects between the HT and non-HT exchanged intensity are operative.