Thermoluminescent spectra and optical absorption in CaSO₄:Dy

Thermoluminescence characteristics of LiNaSO4 doped with rare earths Eu and Dy

“…Three peaks are obtained one at around 440 nm and the other two at around 475 and 570 nm. The first peak is characteristic of the Eu 2+ emission arising from transitions of the 4f 6 5d configuration to the 8 S 7/2 level of the 4f 7 configuration and the next two peaks can be assigned to the Dy 3+ emission due to the transitions 4 F 9/2 → 6 H 15/2 and 4 F 9/2 → 6 H 13/2 respectively [14][15][16]. It can be further seen in the figure that the excitation spectrum (dashed curve) of the Dy 3+ emission (570 nm) contains not only a band (around 450 nm) corresponding to excitation of the Dy 3+ ion itself confirming that Dy 3+ ions are excited but also a band (around 325 nm) that corresponds to excitation of the Eu 2+ ion giving a clear evidence for the occurrence of energy transfer from Eu 2+ to Dy 3+ ion.…”

Influence of Li dopants on thermoluminescence spectra of CaSO4 doped with Dy or Tm

“…They proposed a simple model to explain why emission spectra are characteristic of Dy 3 þ or Tm 3 þ , even when the lithium impurity was added. A more general model has been suggested by Mathews et al and Morgan et al [22,23], in which the RE ions need act directly at the recombination center, but rather, there could be an energy transfer between the recombination site and the rare earth ion. Whilst these were sensible proposals based on the then available data, both models have weaknesses in the light of data such as that presented here with lower heating rates, and TL data obtained at very low temperature.…”

Thermoluminescence in mixed alkali sulphate phosphors

“…A mechanism of thermoluminescence similar to that suggested for CaSO, : Dy could be operative in the mixed alkali sulphates. 16 The role of Eu is not yet clear. The emission spectra appear to be characteristic of Eu, in that, all Eu doped phosphors described here display the emission band around 420nm.…”