Non-Linear Quenching of Fluorescence and Collision Distance for the Singlet Exciton in Anthracene Crystals

Abstract

The fluorescence peak intensity of anthracene crystals was measured as a function of the incident light intensity, using a pulsed nitrogen laser as an excitation source. Non-linear quenching of fluorescene was observed at higher excitation intensities. The phenomena are interpreted in terms of the bimolecular annihilation of singlet excitons, which takes place much faster than the present detecting system. From the exciton density at the threshold of these phenomena, the upper limit of the collision distance for the singlet exciton was determined to be 40Å. The value obtained is consistent with the dipole mechanism suggested for the collision annihilation of excitons.