Effect of Magnetic Field on the Fluorescence of Tetracene Crystals: Exciton Fission

Abstract
The fluorescence efficiency of tetracene single crystals may be enhanced by as much as 38% in a magnetic field H>2000 G. The enhancement is anisotropic with respect to the orientation of H in the ab plane. It is shown that a magnetically sensitive coupling of singlet states to a double-triplet-exciton state (T1T1) at ∼2.40 eV is an important channel for radiationless decay in crystalline tetracene above 160°K.