High-resolution X-ray absorption spectroscopy as a probe of crystal-field and covalency effects in actinide compounds (FR)

First illustration of the ability of this technique to directly probe the crystal-field splitting in the 5f shell of actinides.

 

This work is to our knowledge the first illustration of the ability of the high-energy resolution fluorescence-detection X-ray absorption spectroscopy (HERFD-XAS) technique to directly probe the crystal-field splitting in the 5f shell of actinides. This is a breakthrough for actinide science, allowing for the easy extraction of desired information from the spectroscopic method, which is easy to interpret and to calculate. Furthermore, the HERFD-XAS technique allows us to resolve the charge-transfer satellites in actinide spectra that were hidden before, thus enhancing the sensitivity to the covalent character of the chemical bonding. Using ThO2 as an example, we show that other common techniques underestimate the crystal-field strength and that ThO2 is not an anionic compound as previously believed.

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S. M. Butorina, K. O. Kvashnina, J. R. Vegelius, D. Meyer and D. K. Shuh. PNAS 113(29), 8093 (2016).