Determination of Uranium Central-Field Covalency with 3d4f Resonant Inelastic X-ray Scattering

Area of Science:

• Actinide Chemistry
• Solid-State Chemistry
• Spectroscopy

Background:

• Understanding metal-ligand bonding is crucial in actinide chemistry.
• Existing methods face challenges in quantifying bonding interactions.

Purpose of the Study:

• To develop and apply a novel experimental strategy for probing actinide-ligand bond covalency.
• To utilize 3d4f resonant inelastic X-ray scattering (RIXS) for electronic structure analysis.

Main Methods:

• Systematic study of uranium(IV) halide complexes ([UX6]2-, X = F, Cl, Br).
• Application of 3d4f resonant inelastic X-ray scattering (RIXS).
• Analysis of RIXS spectral satellites in conjunction with ligand field density functional theory (LF-DFT).

Main Results:

• RIXS spectral satellites were identified and correlated with uranium-ligand bond covalency.
• Sensitivity of satellites to bonding arises from reduced 5f interelectron repulsion and 4f-5f spin-exchange.
• Metal-ligand orbital mixing and 5f radial expansion (central-field covalency) were implicated.

Conclusions:

• 3d4f RIXS provides a powerful tool for quantifying electronic structure in actinides.
• The study demonstrates RIXS as a viable technique for estimating actinide-ligand covalency.