Anion photoelectron spectroscopic and relativistic coupled-cluster studies of uranyl dichloride anion, UO[formula omitted]Cl[formula omitted

Abstract

A joint relativistic coupled-cluster and experimental photoelectron (PE) spectroscopic study of the uranyl dichloride anion, UO2Cl2−, is reported. Sophisticated electronic-structure calculations predict the photodetachment of UO2Cl2− to involve a U 5f electron and to be followed by significant geometry relaxation. Therefore, the adiabatic electron affinity (EAa) of the uranyl dichloride neutral molecule, UO2Cl2, and the vertical detachment energy (VDE) of its anion, UO2Cl2−, provide valuable information about its uranium 5f orbital energies. The EAa value was computed to be 3.15 eV. The VDE value was calculated to be 3.55 eV by augmenting the computed EAa with a shift derived from a Franck–Condon simulation using coupled-cluster potential energy surfaces. The VDE, which corresponds to the highest intensity peak in the PE spectrum, was measured to be 3.69 ± 0.20 eV, in good agreement with the computed value. The origin transition in the PE spectrum, whose electron binding energy corresponds to the EAa, was assigned to the feature at 3.2 ± 0.20 eV, consistent with the computed EAa.