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Title:
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FWO-Institutskolloquium The Actinide Ligand Interaction Laboratory (LILA): Basic Rsearch for Actinides in the ATALANTE facility, CEA, France"
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Category:
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Colloquium
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Begin:
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03.05.2017 10:00
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End:
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03.05.2017 12:00
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Speaker:
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Dr. Guilbaud and Dr. Husar (CEA)
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Contact:
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Dr. Atsushi Ikeda
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Location:
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620/018 - Kleiner Hörsaal Kernphysik
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Content:
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“The Actinide Ligand Interaction Laboratory (LILA): Basic Rsearch for Actinides in the ATALANTE facility, CEA, France”
and
“A New Multi-spectroscopic Electrochemistry Approach in CEA-Marcoule”
(Abstract of the second presentation by Dr. Husar)
X-ray absorption spectroscopy (XAS) in simultaneous combination with electrochemical techniques is a powerful tool to determine the coordination of an actinide complex in a targeted oxidation state. Nearly 20 years ago a pioneering XANES spectroelectrochemistry study by L. Soderholm and co-workers was performed manipulating actinide redox couples by potentiometric control. Since that time ongoing XAS research on monitoring actinide coordination during redox-active processes was limited due to lack on international facilities providing spectroelectrochemical XAS of highly radioactive material.
We introduce a spectroelectrochemical XAS setup at MARS beamline in SOLEIL synchrotron and report experiments tracing in situ the structural change of actinide coordination spheres of targeted redox couples by EXAFS under defined potentiometric control. A transportable electrochemical cell for XAS data and UV vis data acquisition during controlled bulk electrolysis was designed enabling XANES and EXAFS investigation of various radioactive material in solution. Technical parameters of the microcell design are presented next to first in situ EXAFS results of Np redox reactions (depicted in Figure 1). Cycling the redox couple NpO22+/NpO2+ allows tracing the change in Np shell hydration. Moreover the structural change in the equatorial actinyl-oxygen feature is demonstrated by NpO2+/Np4+ redox couple. Based on the in situ Np redox testing, first preliminary results of Pu redox reactivity monitored by UV-vis/NIR spectroscopy are presented. The outcome of this multispectroelectrochemistry project aims at (i) providing an european spectroelectrochemical XAS facility to investigate intermediate species for radioactive compounds, and (ii) obtain further mechanistic insights into the change of metal ion/actinide coordination during redoxactive processes in solution.
The talks will be held in English.
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