Probing Bonding Properties of Pu by High Resolution X-ray Spectroscopy and Computations

The electronic and bonding properties of Pu are fascinating, complex and still not very well understood. We will discuss development and application of experimental and computational high energy resolution X ray spectroscopic approaches for in depth characterisation of actinides (An), and specifically Pu, bonding properties. In a series of state of the art experimental and theoretical studies, we demonstrated that each spectroscopic tool at the An M absorption edge high energy resolution near edge structure (HR XANES), core to core resonant inelastic X ray scattering (CC RIXS), and valence band RIXS (VB RIXS) is sensitive to actinide 5f valence electron density with different level of delocalization in a chemical bond. By combining them into a powerful tool, precise characterization of valence electron configurations and bond covalency can be achieved. These advanced experimental techniques can be used to benchmark theoretical approaches as shown, for example, for PuO2, AnO2 or AnO2+ (actinyl, An=U, Np or Pu).