Nature of the transfer of the electronic excitation energy from Cr3+ to rare-earth ions in garnet crystals

An analysis is reported of the decay of an excited state of donors (chromium ions) interacting with acceptors (rare-earth ions) in garnet crystals. An approximation of static nonradiative energy transfer is used. The probabilities of energy transfer to acceptors located in different coordination spheres are derived from the decay kinetics. The published experimental results on some crystals with the garnet structure are used to find these probabilities and to draw conclusions on the transfer mechanisms. It is shown that in the majority of cases the transfer of energy is governed by a superposition of multipole interactions. A new method is proposed for the determination of the microscopic parameters of the ion–ion nonradiative energy transfer.