Cascade Energy Transfer in CeF₃ Crystals

The emission spectra of the CeF₃ crystals in UV-visible region and their temperature dependence in the range of 6-453K under UV, VUV excitation as well as their excitation spectra (4-25eV) have been studied. The 350nm emission band from perturbed Ce³⁺ can be excited by 295.2 and 302.4nm emissions from the regular Ce³⁺. The 350nm emission band, in turn, can excite the emission bands centered at 470 and 535nm caused by some defects below room temperature. These results show that there is a cascade energy transfer process from regular Ce³⁺ to quenching centers via perturbed Ce³⁺ and defect centers in the CeF₃. Meanwhile, thermoluminescence, giving peaks at about 240 and 300°C has been discovered, and the corresponding deep traps with depth~ leV are found to be a kind of quenching center for CeF₃ luminescence at room temperature.