Charge trapping and mechanism of stimulated luminescence in CaS:Ce,Sm

Optically and thermally stimulated luminescence in CaS:Ce,Sm have been studied. Subsequent to exposure to ionizing radiation, this material can be optically stimulated by infrared laser sources such as an InGaAsP (1.20 μm) laser and a Nd:YAG (1.06 μm) laser. The resulting optically stimulated luminescence is the characteristic Ce3+ doublet emission. This material has a deep trap with a ∼330 °C thermoluminescence peak. However, the thermal stimulation results in both Sm3+ and Ce3+ characteristic emissions. It appears that charge compensation in the form of additional sulfur ions in the interstitials is possible in CaS:Ce,Sm and the charge motion between the Ce3+ ions at different symmetry sites results in Ce3+ emissions from the 330 °C peak.