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 4f6configuration 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 theC4vpoint site symmetry occupied by the rare earth ion were determined, yielding a mean square deviation of a few cmminus;1. The freehyphen;ion parameters were also determined with the aid of excitation spectra. The effect of truncation of the basis set of the2S+1LJlevels on the energy level simulation of the excited levels was also studied.
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