Influence of temperature on the aggregation processes of the NaCl:Eu2+ system

Results are given of optical measurements (optical emission and time decay spectra) on NaCl:Eu2+ samples annealed in the temperature range 20 to 130 0C. By annealing the samples, new emission bands are detected, besides the band that is measured for quenched samples. The time decay constants, measured along the emission bands, are rather independent of the emission wavelength and show a value that at LNT is shorter than at RT, as happens for isolated Eu2+ dipoles in quenched samples. This fact seems to suggest that the aggregates responsible for the above mentioned bands are formed chiefly by weakly interacting Eu2+ dipoles. (author)