The 4f-5d luminescence transitions in cerium-doped LuF₃

Emission and excitation spectra of the Ce3+ ion in LuF3 single crystal were measured at 77 K. The broad bands observed in these spectra were attributed to the parity-allowed electric-dipole 4f ← 5d transitions within Ce3+ ion. No zero-phonon lines were observed, which is indicative of a strong electron-phonon coupling in this host. It is shown that Ce3+ 5d excited configuration splits into five crystal-field components in LuF3. The influence of the crystalline environment on the position of the lowest Ce3+ 5d level is investigated. The energy of the lowest level of the 4f N −15d excited configuration was predicted for all the trivalent rare earth ions embedded in LuF3. Positions of crystal field spitting levels of 4f N −15d configuration relative to the host electronic bands were discussed.