On the rôle of exciton trapping at extended defects in the photodimerization of anthracene

Abstract

It has been suggested that photodimerization of certain molecular crystals is the result of exciton trapping at dislocation sites in the crystal. The exciton trapping properties of an idealized plane defect core and also of the microscopically strained region around the core are investigated theoretically. The theory is applied to the anthracene crystal. It is suggested that core trapping initiates the dimerization, but that compressive strains, set up in the dimerization region after some dimer has been formed, are responsible for the trapping leading to the production of further dimer in the region.