title: Probing the electronic structure of UO+ with high-resolution photoelectron spectroscopy.
abstract: The pulsed field ionization-zero kinetic energy photoelectron technique has been used to observe the low-lying energy levels of UO+. Rotationally resolved spectra were recorded for the ground state and the first nine electronically excited states. Extensive vibrational progressions were characterized. Omega+ assignments were unambiguously determined from the first rotational lines identified in each vibronic band. Term energies, vibrational frequencies, and anharmonicity constants for low-lying energy levels of UO+ are reported. In addition, accurate values for the ionization energies for UO [48,643.8(2) cm(-1)] and U [49,957.6(2) cm(-1)] were determined. The pattern of low-lying electronic states for UO+ indicates that they originate from the U3+(5f3)O2- configuration, where the uranium ion-centered interactions between the 5f electrons are significantly stronger than interactions with the intramolecular electric field. The latter lifts the degeneracy of U3+ ion-core states, but the atomic angular momentum quantum numbers remain reasonably well defined.
authors.affiliation: Department of Chemistry, Emory University, Atlanta, Georgia 30322, USA.
authors.forename: Vasiliy
authors.initials: V
authors.lastname: Goncharov
authors.forename: Leonid A
authors.initials: LA
authors.lastname: Kaledin
authors.forename: Michael C
authors.initials: MC
authors.lastname: Heaven