Exploring the pre-edge features of the Resonant Inelastic X-ray Scattering maps of actinide systems

The most debated question to resolve the pre-edge structure of the Actinide (An) L3 XANES is whether the pre-edge structure is due to the dipole allowed (2p-6d) or quadrupole allowed (2p-5f) transitions. If 5f states can be probed at the pre-edge, it will carry important information about the participation of 5f orbitals in bonding as well as the Coulomb and exchange interactions within the 5f shell. We propose to improve the fundamental understanding of the pre-edge transitions by investigating AnO2 systems (An = U, Np, Pu) by means of RIXS and XANES in the HERFD mode at the U L3 edge. The LB5 emission line will be recorded with the ROBL emission spectrometer and incident energy will be selected by Si(311) monochromator, which enables the acquisition of spectra with a substantial gain in resolution. In combination with the experimental results, we will use theoretical methods to provide valuable insights into the electronic structure of the f-electron systems.