Mechanisms for three-centre energy pooling in lanthanide doped crystals

Summary form only given. The migration of excitation energy within dielectric crystals doped with lanthanide ions is a rich area for the study of mechanisms involving both conventional pairwise resonance energy transfer and more complex many-body effects. Within the framework of molecular quantum electrodynamics, we present a delineation of systems undergoing simultaneous transfer from two pre-excited donor ions to a single ground-state acceptor, termed three-centre energy pooling. Calculations lead to the identification of two competing mechanisms of transfer co-existing in each system-one cooperative pathway where the excitation is transferred directly to the acceptor from both donors, alongside an accretive mechanism where the excitation energy of one donor is accrued by a second, with net transfer to the acceptor ensuing.