The electronic structure, spectra, and magnetic properties of actinyl ions: Part II. Neptunyl, and the ground states of other actinyls

Abstract

The ground state of the neptunyl ion is shown to be 2 Φ ( 5 2 )u on the basis of magnetic susceptibility experiments, and energy calculations which include spin-orbital coupling and ligand field effects. It is shown that the electronic spectrum of NpO 2 ++ may be accounted for entirely by intra-5 f-shell transitions. A low-energy infrared electronic transition in the range 2000–4000 cm −1 is predicted for the neptunyl ion, but has not thus far been observed. The ground states, electron configurations, and magnetic susceptibilities of PuO 2 ++, NpO 2 ++, AmO 2 ++. PuO 2 +, AmP 2 +, and UO 2 + are also discussed.