On a Cs 2 NaEuF 6 powder sample, we collected room temperature PL emission data (Figure ). Because of the O h site symmetry of Eu 3+ , we would expect to observe only the 5 D 0 → 7 F 1 transition with one peak. Instead, we see each of the 5 D 0 → 7 F J (J = 0-4) transitions, with one of three J = 1 peaks being the most intense. Many factors can lead to observing the additional transitions, including site disorder in the NaEuF 4 impurity, oxygen or Eu 2+ defects in the structure, or other defects. In the spectrum, the wavenumber shift between the observed 5 D 0 → 7 F 1 and 5 D 0 → 7 F 0 transitions is 365 cm -1 (45.3 meV), which is close to the 43.6 meV energy separation between the 7 F 0 and 7 F 1 levels calculated from magnetometry data.