title: The deuterium/hydrogen distribution in chondritic organic matter attests to early ionizing irradiation.
abstract: Primitive carbonaceous chondrites contain a large array of organic compounds dominated by insoluble organic matter (IOM). A striking feature of this IOM is the systematic enrichment in deuterium compared with the solar hydrogen reservoir. This enrichment has been taken as a sign of low-temperature ion-molecule or gas-grain reactions. However, the extent to which Solar System processes, especially ionizing radiation, can affect D/H ratios is largely unknown. Here, we report the effects of electron irradiation on the hydrogen isotopic composition of organic precursors containing different functional groups. From an initial terrestrial composition, overall D-enrichments and differential intramolecular fractionations comparable with those measured in the Orgueil meteorite were induced. Therefore, ionizing radiation can quantitatively explain the deuteration of organics in some carbonaceous chondrites. For these meteorites, the precursors of the IOM may have had the same isotopic composition as the main water reservoirs of the inner Solar System.
authors.affiliation: UMET, Université Lille 1, CNRS UMR 8207, Villeneuve d'Ascq F-59655, France.
authors.forename: Boris
authors.initials: B
authors.lastname: Laurent
authors.affiliation: UMET, Université Lille 1, CNRS UMR 8207, Villeneuve d'Ascq F-59655, France.
authors.forename: Mathieu
authors.initials: M
authors.lastname: Roskosz
authors.affiliation: IMPMC, CNRS UMR 7590, Sorbonne Universités, Université Pierre et Marie Curie, IRD, Muséum National d'Histoire Naturelle, CP 52, 57 rue Cuvier, Paris 75231, France.
authors.forename: Laurent
authors.initials: L
authors.lastname: Remusat
authors.affiliation: IMPMC, CNRS UMR 7590, Sorbonne Universités, Université Pierre et Marie Curie, IRD, Muséum National d'Histoire Naturelle, CP 52, 57 rue Cuvier, Paris 75231, France.
authors.forename: François
authors.initials: F
authors.lastname: Robert
authors.affiliation: UMET, Université Lille 1, CNRS UMR 8207, Villeneuve d'Ascq F-59655, France.
authors.forename: Hugues
authors.initials: H
authors.lastname: Leroux
authors.affiliation: LASIR, Université de Lille 1, CNRS UMR 8516, Villeneuve d'Ascq F-59655, France.
authors.forename: Hervé
authors.initials: H
authors.lastname: Vezin
authors.affiliation: UMET, Université Lille 1, CNRS UMR 8207, Villeneuve d'Ascq F-59655, France.
authors.forename: Christophe
authors.initials: C
authors.lastname: Depecker
authors.affiliation: Institut M.E. Chevreul, Université de Lille 1, CNRS, FR 2638, Villeneuve d'Ascq F-59655, France.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Nuns
authors.affiliation: UMET, Université Lille 1, CNRS UMR 8207, Villeneuve d'Ascq F-59655, France.
authors.forename: Jean-Marc
authors.initials: JM
authors.lastname: Lefebvre