Spectra of divalent samarium in LaF3 crystals

The optical spectra and electrical conductivity of LaF 3 crystals containing Sm 2+ ions are studied. Groups of emission lines at 560–620, 650–690, and 680–770 nm at 7.9 K are produced by transitions from states 5 D 2 , 5 D 1 , and 5 D 0 to states 7 F j of Sm 2+ ions. Radiative transitions from state 5 D 0 are characterized by a decay time of 8.9 ms and temperature quenching in the range of 70–160 K. A linear dependence of the crystals’ electrical conductivity on the magnitude of absorption bands of Sm 2+ ions is observed, due the presence of anionic vacancies that compensate for the low charge of Sm 2+ ions. The long-wavelength absorption band at 600 nm that is not observed in the excitation spectra is produced by the transition from 4 f Sm 2+ to the 1 s level of anion vacancies. Absorption bands with wavelengths below 520 nm are due to 4 f -5 d transitions in the Sm 2+ ions.