Infrared Dispersion Measurements and Integrated Absorption Coefficients for Pure Liquid Benzene

Abstract

The refractive index of pure liquid benzene has been measured in the 2‐to 21‐μ region to an accuracy of about ±0.003 using an interferometric technique developed by Kagarise and Mayfield. A general relation is derived between the refractive index and integrated absorption coefficients of a pure liquid. The relation is used to determine the absolute intensities of the fundamental vibrations of pure liquid benzene from the dispersion data. A comparison is made with the same intensities determined in the direct absorption measurements of Hisatsune and Jayadevappa. The dispersion values appear to be higher than the absorption results, the difference being about 40% for the 14.8 μ fundamental where the most accurate comparison is possible. A comparison between pure liquid and gas intensities is also made. A brief discussion is given of the advantages and limitations of the dispersion method in determining integrated intensities in liquids.