Ion Microprobe Determination of Hydrogen Concentration and Isotopic ratio in Extraterrestrial Metallic Alloys |
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| Authors: | Céline Defouilloy Rémi Duhamel François Robert |
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| Institution: | Laboratoire de Minéralogie et de Cosmochimie du Muséum, Muséum National d'Histoire Naturelle, , Paris, 75005 France |
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| Abstract: | The isotopic ratio of hydrogen was measured in an iron meteorite and terrestrial native iron using an IMS 3f ion microprobe. The extraterrestrial D/H ratio (93 ± 9 × 10?6) was close to the terrestrial value (105 ± 6 × 10?6), and both samples had low H concentrations (7 ± 4 and 33 ± 11 ng g?1 for the iron meteorite and the terrestrial sample, respectively). Experiments on artificially D‐enriched samples showed that the measured hydrogen signal is a combination of indigenous H and terrestrial atmospheric contamination. This contamination comes from the isotope exchange reaction between water adsorbed on the sample surface and atmospheric water, and would be continuously added to the indigenous H in the ion crater by the adsorbed water sinking into the crater during sputtering. Experiments showed that this contamination represents up to 20% of the signal but was within the uncertainty of the measured D/H ratio. |
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| Keywords: | hydrogen isotopes metallic alloys contamination iron meteorites l'hydrogè ne isotopes alliages mé talliques contamination mé té orites de fer |
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