Effect of Medium on the Intensity of Infrared Absorption Bands

Abstract

The paper presents an extensive study of the solvent effect upon the intensity of ir absorption bands. Because of the special importance of the (X—H) bonds =C, O, H), this study is restricted to the (N—H) and the (O—H) bonds of diphenylamine and α-naphthol, respectively. An easy way to calculate the integrated intensity directly from the record chart, saving much time and effort and avoiding a source of appreciable error, has been developed. The determination of the intensity in the gas phase (A_g) is difficult. An extrapolation method for determining (A_g) is presented. The values found are:

$\begin{array}{c}{A}_g(\text{N}-\text{H})=21.6\times {10}^{-8}\\ A_g(\text{O}-\text{H})=32.5\times {10}^{-8}\end{array}\}$

It is also found that the absolute solvent interactions play an important role in the intensity variation.