An Approximate Method for the Calculation of the Infrared Molar Absorption Coefficient and Absorption Index Spectra of Liquids from Transmission Measurements

Abstract

A simple and effective approximate method for the calculation of infrared molar absorption coefficient spectra, E-m(), and absorption index spectra; k(), of liquids from transmission measurements is presented. In the approximate method, the apparent absorbance due to reflection losses is calculated by assuming the cell is a single window. This simplifies the correction of the experimental absorbance for the contribution of reflection and eliminates the need for an iterative calculation. Although simpler, the method gives k and E-m values accurate to 1% for all but the strongest infrared absorptions. Areas under these spectra are accurate to 0.5%. The method is demonstrated on a mixture of 90 mole% toluene and 10 mole% chlorobenzene.