A new possibility for determining vibration frequencies of organic molecules in the excited electronic state from fluorescence spectra

Abstract

The dependence of the fluorescence spectra of some aromatic hydrocarbons and phthalocyanines in solid solutions at 4.2 K on the frequency of laser excitation has been studied. It has been found that “multiplets” exist in the fluorescence spectra in the case when laser excitation occurs in the vibronic transition region. The structure of these “multiplets” does not depend on the solvent but changes considerably with a change of laser frequency. It has been shown that by analysing the above-mentioned “multiplets” one can obtain frequencies of vibrations of the investigated molecules in excited electronic states.