‘Excimer’ fluorescence V. Influence of solvent viscosity and temperature

Abstract

Abstract The fluorescence characteristics of pyrene solutions in seven different solvents were studied at temperatures from – 100 to 90 °C. Observations were made of the relative quantum yields of excimer and monomer fluorescence and of the fluorescence spectra and time characteristics. The data, which were analyzed to determine the rate parameters and their associated activation energies, are consistent with an excimer formation process which is diffusion-controlled and reversible. The pyrene excimer binding energy B = 0·40 (± 0·01) eV and its radiative transition probability kf D = 1·2 x 107s-1 are independent of the solvent and of the temperature. This indicates that the excimer has a stable steric configuration.