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Institut de minéralogie, de physique des matériaux et de cosmochimie

Electron Paramagnetic Resonance spectrometer


Electron paramagnetic resonance spectrometer (EPR) EMX-plus (Bruker)


Electron paramagnetic resonance is a physical method providing information on the nature, environment and concentration of paramagnetic species, i.e. those with unpaired electrons. Our spectrometer can operate with a microwave frequency of 9.5 GHz (X-band) or 30 GHz (Q-band) and is equipped with a nitrogen cryostat.

The paramagnetic species currently analyzed in our lab are ions of transition elements (Cr3+, Mn2+, V4+, Fe3+, Cu2+) either diluted or locally concentrated, radiation-induced defects in minerals or organic free radicals. Specifically, the fine analysis of Fe3+ in clay minerals brings evidence of different generations of the same mineral associated with various conditions of formation in the environment. Besides, radiation-induced defects in clay minerals are analyzed using calibration performed from artificial irradiations. This is applied to the identification of radiolytic processes, the reconstruction of past migrations of radioelements in natural analogues of high level nuclear waste repositories, in U-ore deposits, or the dating of ancient tropical soils. Iron complexed to colloidal organic matter is specifically used as a tracer of sources of erosion in the Amazon basin.




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