Dynamical processes involving local modes for rare earth centers in CaF 2

Abstract

H -, D - and T - ion local modes play a significant role in dynamical processes involving laser excitation of hydrogenic rare-earth ion centers in CaF 2 and SrF 2. The hydrogenic varieties of a particular center are found to have substantially reduced fluorescence lifetimes supportive of models for non-radiative decay to lower energy multiplets through the respective local mode phonons. Likewise, upconversion efficiencies are reduced for the hydrogenic single rare-earth ion centers and are found to vary with inter-center separation consistent with a recent model for single ion upconversion involving a weak coupling between nearby equivalent centers. The efficient channelling of the rare-earth ion excitation into the creation of local mode phonons can induce hydrogenic ion migration to produce re-oriented equivalent centers or new photoproduct centers with different excitation wavelengths.