Confusion between Raman spectrum and luminescence: a case study of Eu3+ in Cs2NaEuCl6.

Some lanthanide ions have electronic energy levels extending from the far infrared to the vacuum ultraviolet. Without cross-relaxation between levels and other nonradiative depopulation mechanisms, and with adequate spacing between the energy levels, luminescence can be observed. When recording a Raman spectrum of a lanthanide compound, care should be taken to select an appropriate wavelength to avoid luminescence. Two recent examples illustrate results when this is not followed. When recording a Raman spectrum of a lanthanide compound, care should be taken to select an appropriate wavelength to avoid luminescence. • Interpretation of electronic spectra of double halide perovskites • Distinction of Raman and luminescence spectra • Guidelines for recording Raman spectra