Spectroscopic study and crystal-field analysis ofCm3+in the cubic-symmetry site ofThO2

Fluorescence and excitation spectra of ${\mathrm{Cm}}^{3+}$ diluted in ${\mathrm{ThO}}_2$ powder are reported at room and low temperatures. The observed ${\mathrm{Cm}}^{3+}$ spectra are from the cubic symmetry lattice site and are assigned to phonon-assisted electric dipole transitions and to magnetic dipole transitions. From these assignments, the crystal-field parameters ${\mathit{B}}_0^4$=-6436 ${\mathrm{cm}}^{\mathrm{-}1}$ and ${\mathit{B}}_0^6$=1195 ${\mathrm{cm}}^{\mathrm{-}1}$ have been determined. The experimental energy levels for the ground term (∼80% ${}_{}{}^8{}_{}{}^{}$ ${\mathit{S}}_{7/2}$) determined from the optical data and earlier electron paramagnetic resonance spectra are in good agreement with the calculated values.