Vibronic transitions in the absorption spectrum of a U³⁺-doped elpasolite single crystal

Conclusions

We have presented the absorption bands associated with f−f and f−d transitions. The investigated ion was placed in the center of symmetry. For that reason pure electric dipole f−f transitions are forbidden, but thet are allowed for f−d transitions. Nevertheless, pronounced vibronic transitions were obseved not only in the f−f lines but also for f−d bands. An assignment of the observed lines supported by previously reported Raman and IR spectra is proposed.