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The structural characterisation of actinide nanoparticles (NPs) is of primary importance and hard to achieve, especially for non‐homogeneous samples with NPs less than 3 nm. By combining high‐energy X‐ray scattering (HEXS) and high‐energy‐resolution fluorescence‐detected X‐ray absorption near‐edge structure (HERFD XANES) analysis, we have characterised for the first time both the short‐ and medium‐range order of ThO2 NPs obtained by chemical precipitation. By using this methodology, a novel insight into the structures of NPs at different stages of their formation has been achieved. The pair distribution function revealed a high concentration of ThO2 small units similar to thorium hexamer clusters mixed with 1 nm ThO2 NPs in the initial steps of formation. Drying the precipitates at around 150 °C promoted the recrystallisation of the smallest units into more thermodynamically stable ThO2 NPs. HERFD XANES analysis at the thorium M4 edge, a direct probe for f states, showed variations that we have correlated with the breakdown of the local symmetry around the thorium atoms, which most likely concerns surface atoms. Together, HEXS and HERFD XANES are a powerful methodology for investigating actinide NPs and their formation mechanism. [ABSTRACT FROM AUTHOR]

Invited for the cover of this issue is Lucia Amidani and co‐workers from the The European Synchrotron, Helmholtz Zentrum Dresden‐Rossendorf, Lomonosov Moscow State University, Kurchatov Institute, and the Université Grenoble Alpes. The image depicts the atomic structure of the sample being viewed through "atomic googles", which represent the X‐ray techniques used in this work. Read the full text of the article at 10.1002/chem.202003360. [ABSTRACT FROM AUTHOR]

Keywords: actinides; nanoparticles; thorium; X-ray absorption spectroscopy; X-ray scattering EN actinides nanoparticles thorium X-ray absorption spectroscopy X-ray scattering 1 1 1 01/06/21 20210104 NES 210104 B Oh, now I see b ! The precipitates formed during Th SP IV sp hydrolysis are ThO SB 2 sb nanoparticles, which in their initial stages of formation are a mixture of ultra-small nanoparticles and Th hexamer clusters. Actinides, nanoparticles, thorium, X-ray absorption spectroscopy, X-ray scattering. [Extracted from the article]

The structural characterisation of actinide nanoparticles (NPs) is of primary importance and hard to achieve, especially for non‐homogeneous samples with NPs less than 3 nm. By combining high‐energy X‐ray scattering (HEXS) and high‐energy‐resolution fluorescence‐detected X‐ray absorption near‐edge structure (HERFD XANES) analysis, we have characterised for the first time both the short‐ and medium‐range order of ThO2 NPs obtained by chemical precipitation. By using this methodology, a novel insight into the structures of NPs at different stages of their formation has been achieved. The pair distribution function revealed a high concentration of ThO2 small units similar to thorium hexamer clusters mixed with 1 nm ThO2 NPs in the initial steps of formation. Drying the precipitates at around 150 °C promoted the recrystallisation of the smallest units into more thermodynamically stable ThO2 NPs. HERFD XANES analysis at the thorium M4 edge, a direct probe for f states, showed variations that we have correlated with the breakdown of the local symmetry around the thorium atoms, which most likely concerns surface atoms. Together, HEXS and HERFD XANES are a powerful methodology for investigating actinide NPs and their formation mechanism. [ABSTRACT FROM AUTHOR]

Invited for the cover of this issue is Lucia Amidani and co‐workers from the The European Synchrotron, Helmholtz Zentrum Dresden‐Rossendorf, Lomonosov Moscow State University, Kurchatov Institute, and the Université Grenoble Alpes. The image depicts the atomic structure of the sample being viewed through "atomic googles", which represent the X‐ray techniques used in this work. Read the full text of the article at 10.1002/chem.202003360. [ABSTRACT FROM AUTHOR]