| People | Locations | Statistics |
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| Naji, M. |
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| Motta, Antonella |
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| Aletan, Dirar |
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| Mohamed, Tarek |
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| Ertürk, Emre |
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| Taccardi, Nicola |
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| Kononenko, Denys |
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| Petrov, R. H. | Madrid |
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| Alshaaer, Mazen | Brussels |
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| Bih, L. |
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| Casati, R. |
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| Muller, Hermance |
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| Kočí, Jan | Prague |
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| Šuljagić, Marija |
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| Kalteremidou, Kalliopi-Artemi | Brussels |
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| Azam, Siraj |
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| Ospanova, Alyiya |
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| Blanpain, Bart |
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| Ali, M. A. |
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| Popa, V. |
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| Rančić, M. |
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| Ollier, Nadège |
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| Azevedo, Nuno Monteiro |
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| Landes, Michael |
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| Rignanese, Gian-Marco |
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Remusat, Laurent
French National Centre for Scientific Research
in Cooperation with on an Cooperation-Score of 37%
Topics
Publications (8/8 displayed)
- 2023Combination of ERDA, FTIR spectroscopy and NanoSIMS for the characterization of hydrogen incorporation in natural diamondscitations
- 2018Kinetic D/H fractionation during hydration and dehydration of silicate glasses, melts and nominally anhydrous mineralscitations
- 2018Long-term weathering rate of stained-glass windows using H and O isotopescitations
- 2016The composition of nanogranitoids in migmatites overlying the Ronda peridotites (Betic Cordillera, S Spain): the anatectic history of a polymetamorphic basementcitations
- 2014Isotopic and structural signature of experimentally irradiated organic mattercitations
- 2013Amorphization and D/H fractionation of kerogens during experimental electron irradiation: Comparison with chondritic organic mattercitations
- 2013Amorphization and D/H fractionation of kerogens during experimental electron irradiation: Comparison with chondritic organic mattercitations
- 2012High resolution TEM of chondritic carbonaceous matter: Metamorphic evolution and heterogeneitycitations
Places of action
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article
Amorphization and D/H fractionation of kerogens during experimental electron irradiation: Comparison with chondritic organic matter
Abstract
Irradiation is common in the interstellar medium and the protosolar nebula. We have investigated the effects of electron irradiation on kerogens of type I and III in a 200 kV transmission electron microscope (TEM), at 293 K and 92 K, using various fluences. Using synchrotron-based scanning transmission X-ray microscopy (STXM) and NanoSIMS, we have demonstrated a progressive amorphization coupled with hydrogen loss and a significant deuterium to hydrogen ratio (D/H) fractionation, with dD increasing by up to 1000‰. Hydrogen loss is non-linearly related to the fluence. Irradiation under cryogenic conditions (92 K) hinders amorphization and D/H elevation. We suggest that these effects are controlled by radiolysis (carbonAhydrogen bonds are broken and hydrogen is lost), coupled with recombination. The amorphization and hydrogen loss are rate-limited by defect diffusion which controls the recombination probability. The D/H increase appears to follow a Rayleigh distillation law with an apparent fractionation factor similar to the equilibrium fractionation factor of the isotopic exchange reaction CH4 + HDMCH3- D + H2. This study represents a first step to estimate the kinetics and timescales of D/H fractionation under ionizing radiation. Extrapolatation of this fractionation behavior to natural environments remains difficult at this point because simultaneous irradiation by protons and other cosmic rays at various energies also occurs. However, the present results show that isotopic fractionation by electron irradiation at 200 kV alone might have been kinetically inhibited at the low temperatures of the interstellar medium and the outer region of the protosolar nebula. In addition, we show that STXM or NanoSIMS experiments should not be performed on organic samples that have already been investigated using TEM, even under low flux electron irradiation conditions.