Inverse photoemission of the light actinide metals and dioxides

Abstract

Inverse photoemission spectroscopy (IPES) operating in the isochomat mode (≈10 eV) has been used to probe the unoccupied states in the actinide dioxides of thorium, uranium and plutonium, and the actinide metals of thorium, uranium, α-plutonium and a plutonium-gallium alloy, δ-Pu(Ga). The IPE spectra of the dioxides show a signal predominantly occurring from the 5f unoccupied states and where possible have been curve fit to obtain the 5f5/2 – 5f7/2 spin orbit coupling and intensity values. Combined with the HeI Ultraviolet Photoelectron Spectroscopy of the actinide dioxides the band gap values have been determined. The IPE spectra of the metals show a weak signal on a large background contribution with little difference between the α- and δ-Pu(Ga) phases. The IPE spectra of the metals have been used to aid interpretation of the possible screening mechanisms in the 4f core level photoelectron spectra. Photoelectric work functions for these materials are also reported. UK Ministry of Defence © Crown Owned Copyright 2021/AWE