LASER SPECTROSCOPY OF UO: CHARACTERIZATION, LIGAND FIELD ASSIGNMENTS AND DEPERTURBATION ANALYSIS OF STATES IN THE 0-3 eV RANGE
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Date
1993
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Ohio State University
Abstract
Wavelength-resolved fluorescence excitation techniques have been used to record thirty-three electronic transitions of UO at a resolution of $0.03 cm^{-1}$. Nine low-lying electronic states that correlate with $U^{2}+(5f^{3}7s)O^{2-}$ and $U^{2+}(5f^{2}7s^{2})O^{2-}$ were characterized. With few exceptions, $\Omega$ assignments were unambiguously determined from observations of the first lines in at least two rotational branches. Deperturbed constants of $\omega_{e}=850.8 cm^{-1}$ and $r_{e}=1.8378$ {\AA} have been determined for the ground state of the $5f^{3}7s$ configuration, and $\omega_{e}=928.6 cm^{-1}$ and $r_{e}=1.7851$ {\AA} for states of the $5f^{2}7s^{2}$ configuration. Fitted values for the ligand field parameters $B^{2}_{0}(5f)=10270 cm^{-1}, B^{4}_{0}(5f)=621 cm^{-1}$. and $B^{6}_{0}(5f)=173 cm^{-1}$ strongly differ from their relativistic Dirac-Fock values: $B^{2}_{0}(5f)=24000 cm^{-1}, B40(5f)=9000 cm^{-1}$, and $B^{6}_{0}(5f)=6000 cm^{-1}.$ Ligand field theory calculations have been used in an attempt to provide configurational assignments for the excited states of UO. The energies of 23 electronic configurations of UO, and 19 electronic configurations of $UO^{+}$, have been calculated. The density distribution of bound states for UO and $UO^{+}$ up to their ionization limits was also calculated.
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Author Institution: Department of Chemistry, Emory University Atlanta