Vacuum ultraviolet photoluminescence of NaMgF3:Sm and NaMgF3:Sm,Ce: energy levels of the lanthanides in NaMgF3:Ln compounds

The luminescence properties of NaMgF3:Sm and NaMgF3:Ce,Sm were studied in the vacuum ultraviolet spectral region. Excitation bands corresponding to the charge transfer processes F− → Sm3+, O2− → Sm3+, and O2− → Ce3+, and the energy transfer processes Ce3+ → Sm3+ and O2− → Sm3+, were observed. The energies of the Sm3+ charge transfer transitions and the crystal field split Ce3+ 4f 05d 1 transitions were used to construct a complete host referred binding energy diagram for the series of lanthanide-doped NaMgF3:Ln compounds. We demonstrate that the optical and luminescence properties predicted by the binding energy diagram are in good agreement with those predicted by the binding energy diagram constructed via the alternative impurity-informed method, and all available experimental data regarding the NaMgF3:Ln compounds. We demonstrate that NaMgF3:Ln compounds are model systems for the study of charge trapping phenomena and divalent lanthanide luminescence. Ultimately, we validate that the impurity-informed method can be used to establish the energy levels of lanthanides in fluoride systems.