Anion photoelectron spectroscopic and relativistic coupled-cluster studies of uranyl dichloride anion, UO2Cl2−

Abstract A joint relativistic coupled-cluster and experimental photoelectron (PE) spectroscopic study of the uranyl dichloride anion, UO 2 Cl 2 − , is reported. Sophisticated electronic-structure calculations predict the photodetachment of UO 2 Cl 2 − to involve a U 5f electron and to be followed by significant geometry relaxation. Therefore, the adiabatic electron affinity (EA a ) of the uranyl dichloride neutral molecule, UO 2 Cl 2 , and the vertical detachment energy (VDE) of its anion, UO 2 Cl 2 − , provide valuable information about its uranium 5f orbital energies. The EA a value was computed to be 3.15 eV. The VDE value was calculated to be 3.55 eV by augmenting the computed EA a 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 EA a , was assigned to the feature at 3.2 ± 0.20 eV, consistent with the computed EA a .