Many-Body Processes in Nonradiative Energy Transfer between Ions in Crystals

Abstract

It is shown that many‐body interactions can play a dominant role in nonradiative energy transfer processes between ions in crystals. These interactions formally arise from the Coulomb and exchange interactions between the electrons of the donor ion and two or more acceptor ions. In particular, three‐body transfer processes arising from the dipole‐dipole perturbation Hamiltonian through virtual transitions are considered in some detail. Such processes are manifested by the quadratic concentration dependence of the per‐ion nonradiative energy transfer rate observed in concentration quenching and sensitized luminescence experiments. Many‐body interactions are important in rare‐earth ions because of the narrow widths of the 4fⁿ crystal states and because of the large moments of the virtual transitions involving the opposite parity 4fⁿ⁻¹ 5d states.