Séminaire du jeudi 29 novembre 2012 à 10H

IMPMC, Université P. et M. Curie, 4, Place Jussieu, 75005 Paris

Salle de Conférence, 4ème étage, Tour 22-23, Salle 401

URANIUM (AND PLUTONIUM) AT SOLID/WATER INTERFACES: LESSONS TO BE LEARNED FROM XRAY ABSORPTION SPECTROSCOPY

Andreas SCHEINOST (Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiochemistry, Dresden, Germany)

Résumé :

X-ray absorption spectroscopy is a versatile tool to investigate oxidation state and
molecular structure of uranium in aqueous and solid phases and at their common
interface. However, the structural analysis is often hampered by limited resolution
and range. I will show recent advances to overcome these limitations, including
improved XAFS data analysis approaches like Monte-Carlo and Landweber methods
and modern data mining methods; and coupling to XAFS-independent methods like
DFT and surface complexation modeling.
I will demonstrate the usefulness of these methods by showing recent results on
uranyl sorption to mineral surfaces, with a focus on polynuclear and carbonate
complexes; Fe(II)-driven interfacial redox processes of uranyl, also in comparison to
other actinoides; colloid formation processes of U(IV) and its tetravalent actinoide
neighbors.