Time-resolved fluorescence of jet-cooled carbazoles and their weak complexes

Abstract

The fluorescence spectroscopy of carbazole, N-ethylcarbazole, fluorene, 9-ethylfluorene and dibenzofuran cooled in a supersonic jet expansion have been described. A detailed study of the fluorescence decay times of carbazole and N-ethylcarbazole has revealed that the fluorescence quantum yields of the zero-point levels of both compounds are unity, and that there is little variation with excess energy. The onset of intramolecular vibrational redistribution does not lead to any observable change in electronic relaxation rate. The fluorescence excitation spectra of ground-state complexes of differing stoichiometry of N-ethylcarbazole with argon, acetonitrile, methanol, chloroform, diethyl ether and triethylamine have been recorded, and decay times have been measured. In no case was solution-phase behaviour mimicked by complexation of the carbazole species with up to three added solvent molecules.