Microwave-perturbed static-magnetic-field delayed-fluorescence modulation experiments in anthracene

Abstract

The fusion of free triplet excitons in anthracene crystals at room temperature has been investigated by detection of the changes induced in the delayed fluorescence by a microwave field perturbing a static magnetic field applied to the crystal. This allowed detection of resonances at pair energy levels other than the degenerate one at which the static high-field resonances can be seen. A detailed study in the ab plane gave good agreement with the currently accepted energy-level diagram for the pair states. Possible approaches to account for the observed resonance intensities and linewidths are discussed.