Aggregation Processes in the NaCl:Eu 2+ , Mn 2+ System and Energy Transfer Mechanisms

Energy transfer processes are studied in NaCl:Eu 2+ , Mn 2+ samples, along the annealing treatments that are performed at RT and at 100 °C; the Eu ions and/or Eu aggregates act as donors and Mn ions and/or Mn aggregates act as acceptors. For the samples annealed at RT, a single pair transfer mechanism is evidenced at the early annealing stages, while at late annealing stages a fast energy migration in the donor system followed by a phonon assisted transfer is observed. For the annealing at 100 °C at late aggregation stages the most probable transfer process seems to be connected to a slow energy diffusion in the donor system followed by the transfer to the acceptors. The Mn 2+ emission band, that is detectable as a consequence of the EuMn transfer shows a complex behaviour.