On the role of the 4f-Lu level in the scintillation mechanisms of cerium-doped lutetium-based fluoride crystals

Abstract

Optical properties of two pairs of Ce3+-doped scintillating materials, (LiLuF4, LiYF4) and LuF3, LaF3), are presented. 4f14→4f13-5d transitions of Lu3+ are shown to occur between 8–10 eV in the transmission spectra of the Lu-based compounds. in this domain, the transfer of electronic excitation from lutetium to crerium is inefficient, the transmission spectra and the corresponding Ce3+ excitation spectra being anticorrelated. On the contrary, the excitation of Ce3+ is favoured by the presence of lutetium at higher energies, most probably due to the small energy gap between the 4fCe3+ ground state and the 4f14 Lu3+ states forming the top of the valence band.