Migration of excitation energy and fluorescence quenching in regular lattices

Abstract

Intermolecular transfer of excitation energy is studied in model systems containing luminescent donor molecules (D) and acceptor molecules (A) which constitute deep energy traps. It has been assumed that the donor and acceptor molecules form a regular lattice in which the energy transfer takes place in a hopping manner. Within the limits of the model, it has further been assumed that elementary processes are responsible for the deactivation of excited donor molecules (D *). These processes are: fluorescence, internal conversion and non-radiative energy transfer D * → D and D * → A. The general considerations concern the partial and total fluorescence quantum yield of the system and the number of energy transfers before its deactivation. A more detailed analysis and calculations, leading to analytical expressions describing these quantities, have been made for linear systems. It is shown, that has approach, under the conditions where in the system only the migration of energy is observed and no other means of energy deactivation exist leads to the same value of the average number of energy transfers as was obtained earlier by Montroll and a mean relaxation time as given by Movaghar et al.