Probing the electronic structure of UO~+with high-resolution photoelectror spectroscopy

摘要

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 [48643.8(2) cm~(-1)] and U [49957.6(2) cm~(-1)] were determined.The pattern of low-lying electronic states for UO~+indicates that they originate from the U~(3+)(5f~3)O~(2-) configuration,where the uranium ion-centered interactions between the 5/ electrons are significantly stronger than interactions with the intramolecular electric field.The latter lifts the degeneracy of U~(3+) ion-core states,but the atomic angular momentum quantum numbers remain reasonably well defined.