ENERGY-TRANSFER PROCESSES IN ORGANIZED MEDIA .2. GENERALIZATION OF THE CRYSTAL MODEL FOR DIPOLE-DIPOLE INTERACTIONS IN CUBIC SITES

The study of energy transfer processes between optical centers in crys talline cubic materials is reexamined within the conceptual framework of the crystal model. The initial assumption of modest transfer rates is relaxed, thereby correcting the master equation of the crystal mode l and making it possible to explain the nonexponential behavior of the radiation decay curves from excited states. This study shows that suc h experimental trends are the result of a purely statistical effect re lated to the fluctuation in the population of optically active ions in a crystal lattice. The corrected crystal model does not need to invok e migration of excitation processes to explain the fast exponential de cay observed in crystals with a high concentration of optical centers. (C) 1997 American Institute of Physics.