Abstract
The migration of excitation energy from anthracene to tetracene has been studied in a solid solution of the two molecules in naphthalene crystal. Perturbation theory has been used to formulate the probability of transfer of energy from anthracene to tetracene when both are in naphthalene solid solution, and the excellent agreement with the experimental result (probability of fluorescence equals probability of transfer at an intermolecular distance of 44 Ǻ) supports the conclusion that the mechanism operating is dominantly a non-radiative one, adequately described by the dipole-dipole approximation for the interaction between the molecules.