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Interstellar chemistry recorded by nitrogen isotopes in Solar System organic matter |
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| Authors: | Jérôme Aléon François Robert |
| Institution: | a Centre de Recherches Pétrographiques et Géochimiques-CNRS, 15, rue Notre-Dame des Pauvres, BP20, 54501 Vandoeuvre-les-Nancy, France b Muséum National d'Histoire Naturelle, UMS-CNRS 2679, USM-Muséum 205, Laboratoire d'Etude de la Matière Extraterrestre, 61, rue Buffon, 75005 Paris, France |
| Abstract: | The relationship between the organic  and D/H ratios in small Solar System bodies (meteorites, interplanetary dust and comets) suggests that isotopic exchange reactions taking place at various temperatures are at the origin of the observed variations. These relationships are used to determine the exothermicity (ΔE) of ion-molecule reactions that fractionated the nitrogen isotopic ratio in the presolar molecular cloud; that is ΔE=43±10 K. Comparison with current models of interstellar chemistry suggests that such a value could be achieved by condensation of 15N-rich gas-phase precursors onto grain surfaces and their further isolation from the gas by incorporation into large macromolecular structures. |
| Keywords: | Nitrogen isotopes Organic chemistry Solar nebula Molecular clouds |
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