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

Abstract

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⁺, O^2- → Sm³⁺, and O^2- → Ce³⁺, and the energy transfer processes Ce³⁺ → Sm³⁺and O^2- → Sm³⁺, were observed. The energies of the Sm³⁺charge transfer transitions and the crystal field split Ce³⁺4f⁰5d¹transitions 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.

Keywords: NaMgF3; VUV; host referred binding energy; photoluminescence.