Exciton—Phonon Interaction in Crystalline Benzene

Abstract

The uv crystal spectrum of benzene is investigated in the region 4°—80°K. The intensity of the a‐polarized and c‐polarized components of the 0–0 band are temperature dependent. The intensity of the a 0–0 component is found to be proportional to the density of phonons with a frequency of 16 cm^—1. The half‐width of the a and c axis‐polarized 0–0 components are also studied as a function of temperature. The half‐width of the band at 38 786 cm^—1 0–0+925 is similar to that of the purely electronic components, while for the 38990 cm^—1 band 0–0+1155, the half‐width is temperature independent. The mean phonon‐perturbing frequency is 12 cm^—1. The a‐c 0–0 band splitting is studied as a function of temperature. Sample line shapes are reported, and the results are discussed briefly on the basis of the theoretical work of Toyozawa.