SPECTROSCOPY OF PYRENE CLUSTERS FORMED IN A SUPERSONIC JET

The paper is devoted to the study of fluorescence of the pyrene molecu les cooled in a supersonic jet. The dispersed fluorescence spectra of the pyrene molecules under excitation at high electronic states were m easured. It is shown that the pyrene molecules cooled in a supersonic jet produce clusters with excitation and fluorescence spectra maxima a t 30300 and 23000 cm(-1), respectively. The fluorescence spectrum of t hese clusters practically coincides with that of pyrene excimers obser ved in the condensed phase. The fluorescence life-time of the clusters is about 140 ns. The mechanism explaining the formation of excimers b y excitation of clusters is proposed.