Absorption Spectrum of Np${\mathrm{O}}_2^{+2\mathrm{}}$ in CsU${\mathrm{O}}_2$${\left(\mathrm{N}{\mathrm{O}}_3\right)}_3$

The absorption spectrum of Np${\mathrm{O}}_2^{+2\mathrm{}}$ doped in CsU${\mathrm{O}}_2$ ${\left(\mathrm{N}{\mathrm{O}}_3\right)}_3$ has been studied from 5000 to 22 000 ${\mathrm{cm}}^{-1\mathrm{}}$. Nine electronic levels have been identified through their vibronic patterns and magnetic properties. Four of these levels, at 6458, 9420, 17 841, and 20 815 ${\mathrm{cm}}^{-1\mathrm{}}$, are identified as pure electronic excitations within the $5f^1$ configuration. The other five electronic levels at 13 914, 16 071, 16 093, 17 968, and 21 021 ${\mathrm{cm}}^{-1\mathrm{}}$ arise from the excited configuration consisting of two $5f$ electrons and a hole in the bonding electrons. The observed Zeeman effect of the absorption lines at 6458, 9420, 17 841, and 20 815 ${\mathrm{cm}}^{-1\mathrm{}}$ agrees roughly with the calculation reported by Eisenstein and Pryce on the spectrum of Np${\mathrm{O}}_2^{+2\mathrm{}}$ doped in RbU${\mathrm{O}}_2$ ${\left(\mathrm{N}{\mathrm{O}}_3\right)}_3$, whose crystal structure is isomorphous to that of CsU${\mathrm{O}}_2$ ${\left(\mathrm{N}{\mathrm{O}}_3\right)}_3$.