Zero-field splitting ofCm3+inLuPO4single crystals

Electron-paramagnetic-resonance (EPR) spectroscopy has previously been employed in investigating excited levels of the ground-state manifold of the 5${\mathit{f}}^7$-configuration ion ${\mathrm{Cm}}^{3+}$ diluted in single crystals of the tetragonal-symmetry, zircon-structure hosts ${\mathrm{LuPO}}_4$ and ${\mathrm{YPO}}_4$. The three intradoublet resonances that were observed in these earlier studies, however, were significantly broadened due to radiation damage arising from the use of the 18.1-yr half-life isotope ${}_{}{}^{244}{}_{}{}^{}\mathrm{Cm}$. In the present work, the isotope ${}_{}{}^{248}{}_{}{}^{}\mathrm{Cm}$ (${\mathit{T}}_{1/2}$=3.4×${10}^5$ yr) with a significantly lower specific activity has been incorporated in ${\mathrm{LuPO}}_4$-host single crystals in order to reduce the internal radiation-induced damage that can broaden both EPR and optical transitions. By employing these ${}_{}{}^{248}{}_{}{}^{}\mathrm{doped}$ ${\mathrm{LuPO}}_4$ samples, it has been possible to observe an additional interdoublet transition for ${\mathrm{Cm}}^{3+}$, to perform more accurate measurements of the various intradoublet transitions at higher microwave frequencies, and to obtain optical absorption and fluorescence data for this system. These EPR and optical results have led to a more complete and accurate determination of the energy-level structure of ${\mathrm{Cm}}^{3+}$. Additionally, it has been possible to detect magnetic resonance transitions for the ${\mathrm{Cm}}^{3+}$ ion at room temperature.