Energy Transfer Mechanism in the NaCl:Pb++,Mn++ System along Aggregation Processes

The non-radiative energy transfer mechanisms between Pb++ (donor) and Mn++ (acceptor) ions in NaCl:Pb++, Mn++ system are examined at different aggregation stages of the impurities. Mn++ ions are characterized by a series of absorption bands partially overlapping the emission bands of Pb++ aggregates peaking at 380, 430, and 500 to 530 nm. The energy transfer mechanism connected with Pb++-380 nm emission band is based on a resonant single pair interaction, while the transfer process connected with 430 nm and 500 to 530 nm emission bands can be explained on the basis of a fast energy migration within the donor system followed by a final transfer, donor–acceptor, that is resonant for the transfer connected with 430 nm band and phonon assisted for the transfer connected with the 500 to 530 nm band.