Paramagnetic Resonance of the Tripositive Curium Ion in Ethylsulfate and Trichloride Crystals

Abstract

The paramagnetic resonance of the ion ${\mathrm{Cm}}^{3+}$ has been studied by incorporating various amounts of curium in crystals of lanthanum ethylsulfate and anhydrous lanthanum trichloride. For the ethylsulfate crystals, a single line was observed at helium temperatures, characterized by $g_{\mathrm{II}}=1.925\mathrm{}\pm 0.002$ and $g_{\perp }=7.73\mathrm{}\pm 0.02$. A similar line, for which $g_{\mathrm{II}}=1.925\mathrm{}\pm 0.002$ and $g_{\perp }=7.67\mathrm{}\pm 0.02$, occurs for the trichloride crystals. These lines are interpreted as corresponding to transitions within the lowest doublet of the ground level $5f^7{}_{}{}^8{}_{}{}^{}S_{\frac{7}{2}}^{}{}_{}{}^{}$, which, owing to the high degree of intermediate coupling, does not possess the extremely small splitting typical of $S$ states. The Landé $g$ value of the ground level is found to be 1.925. Previous experimental results on the paramagnetic resonance of ${\mathrm{Cm}}^{3+}$, which were difficult to account for theoretically, are shown to be spurious; evidently the reported spectra should have been ascribed to ${\mathrm{Gd}}^{3+}$.