Direct measurement of 5f delocalization with U XES

Delocalization of the 5f states in the early actinides in general and U metal in particular is significantly important and yet poorly understood. Extant spectroscopic techniques have failed to resolve the situation. Here, it will be shown that x-ray emission spectroscopy of the M-4,M-5 levels can provide the needed information, with a distinct difference between the delocalized U metal and localized uranium dioxide and uranium tetrafluoride cases. A peak ratio model, built upon electric dipole selection rules, has been developed and utilized, with quantitative agreement between experiment and theory. Possible expansion to other types of 5f mixing systems will be discussed.

Automated summary

The delocalization of 5f states in the early actinides, specifically in U metal, is a crucial yet poorly understood phenomenon. This study demonstrates that x-ray emission spectroscopy of the M-4,M-5 levels can offer valuable insights and can differentiate between delocalized U metal and localized uranium dioxide and uranium tetrafluoride. A peak ratio model based on electric dipole selection rules has been developed and successfully applied to experimental and theoretical data, with the potential for expansion to other types of 5f mixing systems.