MEASUREMENT AND USE OF ABSOLUTE INFRARED-ABSORPTION INTENSITIES OF NEAT LIQUIDS

This paper describes the methods used in this laboratory to measure absolute infrared absorption intensities of liquids and their applications in analytical and physical chemistry. The applications include the measurement of 43 bands of benzene, toluene, chlorobenzene and dichloromethane as secondary standards of infrared absorption for the international Union of Pure and Applied Chemistry, the use of these standards to calibrate transmission cells, measurement of the absolute intensity spectra of liquid benzene, the comparison of absorption intensities and transition moments in liquid and gaseous benzene, the separation of the integrated intensity of benzene into contributions from different transitions by curve fitting, and the determination of intensities and transition moments of the OH, OD, CH and CD stretching bands of CH3OH, CH3OD, CD3OH and CD3OD. The accuracy of the absolute intensities is impressively shown by the close similarity of the intensities of corresponding bands in the spectra of different isotopomers of methanol. One key to the measurement of accurate intensities is the determination of the baseline absorption.