Matrix perturbations of the benzene1B2ustate

Publisher Website
Google Scholar
Abstract
The fluorescence spectrum of C6H6 in C6D6 is reported. The vibronic analysis shows the crystal-field effect to be much smaller than the Herzberg-Teller vibronic mixing present in the free molecule. Data on the benzene S 1↔S 0 gas-to-crystal shift in this and other host crystals is presented. An approximate calculation of this gas-to-crystal shift in pure crystalline benzene indicates that London dispersion interactions make a significant contribution to the gas-to-crystal shift. The calculated value indicates that the dispersion contributions to the shift are > 187 cm-1 compared to the experimental value of 248 cm-1 (both to the red). The importance of crystal packing in determining the gas-to-crystal shift is emphasized by an attempt to correlate shift data in a number of crystalline matrices. In addition, the deuterium isotope effect on the gas-to-crystal shift, reported previously for isotopic mixed crystals, is found to be generally observed for chemically mixed crystals. Crystal packing effects are also used to explain this isotope effect.