Free ion and crystal field parameters for REOCl : Eu3+

Abstract

The fluorescence spectra of Eu³⁺ activated rare earth oxychlorides REOCl : Eu³⁺ (RE = Y, La, Gd) were recorded and analyzed at 4.2, 77, and 300 K. For each compound more than 100 transitions between the Stark levels of the 4f⁶ configuration were observed and assigned. The energy level schemes established from the spectra show a relatively strong crystal field effect. The five nonzero crystal field parameters for the C_4v point site symmetry occupied by the rare earth ion were determined, yielding a mean square deviation of a few cm⁻¹. The free‐ion parameters were also determined with the aid of excitation spectra. The effect of truncation of the basis set of the ^2S+1L_J levels on the energy level simulation of the excited levels was also studied.