Multiconfigurational nature of 5f orbitals in uranium and plutonium intermetallics

TL;DR

This study uses advanced spectroscopic techniques to demonstrate the multiconfigurational nature of 5f orbitals in uranium and plutonium intermetallics, offering new insights into their complex electronic behavior.

Contribution

It provides the first experimental evidence of multiconfigurational f-orbital states in actinide intermetallics, advancing understanding of their electronic structure.

Findings

Presence of multiconfigurational f-orbital states in U and Pu

Correlation between spectroscopic data and specific heat measurements

Supports a new framework for actinide electronic behavior

Abstract

Uranium and plutonium's 5f electrons are tenuously poised between strongly bonding with ligand spd-states and residing close to the nucleus. The unusual properties of these elements and their compounds (eg. the six different allotropes of elemental plutonium) are widely believed to depend on the related attributes of f-orbital occupancy and delocalization, for which a quantitative measure is lacking. By employing resonant x-ray emission spectroscopy (RXES) and x-ray absorption near-edge structure (XANES) spectroscopy and making comparisons to specific heat measurements, we demonstrate the presence of multiconfigurational f-orbital states in the actinide elements U and Pu, and in a wide range of uranium and plutonium intermetallic compounds. These results provide a robust experimental basis for a new framework for understanding the strongly-correlated behavior of actinide materials.