Influence of the Broadening of Vibrational Bands on the Relative Order of Their Molar Extinction Coefficients

Abstract

The broadening of transitions in the spectra of organic molecules in the liquid phase, under perturbations whose type may be the solvation effects, causes changes of the molar extinction coefficients ∊. The problem has been known for a longtime and several attempts have been made to produce a measure of the width of complex absorption spectra and of their fine structure^(1–4). Nevertheless, nobody has produced a quantitative study of the influence of a given broadening perturbation on the relative values of the ∊ of the various parts of a spectrum. The integrated intensity, because it is a measure of the whole intensity of a transition, cannot give informations about a possible change of intensities inside the vibrational structure of that transition.