Vibrational Intensities of Benzene in the Liquid Phase

The intensities of the four fundamental absorption bands in liquid benzene have been measured by using the Wilson-Wells method. In addition, the intensity of the 15-μ CH bond out-of-plane bending mode absorption band has been measured in cyclohexane, isooctane, methyl formate, and ethyl propionate solutions at five different concentrations. The solution values were in all cases larger than the pure liquid result. The effect of iodine in the most dilute solution of each solvent was also investigated, but no apparent difference from the simple solution was observed. The variations in the intensity, the band width, and the peak frequency with concentration found here suggest the existence of pronounced intermolecular interactions in liquid benzene.