TOTALLY SYMMETRIC VIBRONIC PERTURBATIONS AND PHENANTHRENE 3400-A SPECTRUM

Vibronic perturbations by totally symmetric vibrations are discussed with the help of the linear term in the dependence of transition moment on normal coordinate. Where the dependence is significant, mirror symmetry between fluorescence and absorption spectra is lost, and the fluorescence lifetime differs from the value calculated from the integrated absorption curve. The phenanthrene 3400-Å spectrum, in which totally symmetric vibrational perturbations have previously been identified, can be interpreted in some detail on this basis.