The observation of the excimer formation process in pyrene and perylene crystals using a picosecond ruby laser and streak camera

Abstract

The rise curves of fluorescence from the excimer excitons in pyrene and perylene crystals were observed with the use of the equipment for fluorescence lifetime measurements in the picosecond region. The time constants of excimer formation in pyrene and perylene crystals at 293 and 77 K were found to be considerably shorter than 20 ps. From this result and the previously reported hopping time of excitons in pyrene crystal (20 ps) at room temperature, it is concluded that the sum of the time constants for conformational change of an energy-donating pair and excimer-energy transfer is about 20 ps.