Interpretation of the 4f-5d Excitation Spectra of Eu3+ and Tb3+ Doped in Crystals

The structure of the low-temperature 4fN→4fN−15d excitation spectra of Eu3+ and Tb3+ doped in crystals LiYF4, YPO4 and CaF2 measured by van Pieterson et al. in 2002 was analyzed and assigned based on the simple model proposed by Duan and co-workers in the last few years. Some complemental discussion on effects of J-mixing on the f-d transition intensities for Eu3+ due to the f-electron crystal-field interaction Hcf(f), which was ignored in the simple model, was presented. Some previously unexplained peaks for Tb3+ were interpreted to be spin-forbidden transitions to higher 5d crystal-field levels, or assigned to be f→d excitations with the core 4f7 excited from 8S to 6P, 6I and 6D, respectively. It is shown that the main structure of 4f-5d excitation spectra of Eu3+ and Tb3+ can be well interpreted with the simple model.