Variation of Molybdenum Isotopic Composition in Iron Meteorites
The isotopic composition of molybdenum was determined with high precision for eight iron meteorites and terrestrial samples. The s,rnuclides, 95Mo and 98Mo, were chosen for normalization in order to cancel effects of mass-dependent isotope fractionation. After this normalization, another s,rnuclide 97Mo indicates little isotope anomaly. The only s-process nuclide, 96Mo, shows an anomaly (ε96) ranging from −2.33 to + 1.94. There is a clear positive correlation between ε96 and ε94, while there is a clear negative correlation between 96Mo and the only pure r-process nuclide 100Mo. The relationship between 96Mo and the p-process nuclide, 92Mo, is grossly positive, but the relevant points are rather scattered. The production process of 92Mo is judged to be partially related with that of 94Mo and partially independent of it. These results are very significant for nucleosynthesis and the evolution of the solar system. Great chemical caution was taken against the isobaric effects coming from Zr and Ru, and a special technique was devised to secure a stable, intense ion beam of Mo+ in the mass spectrometer.
KeywordsThermal Ionization Mass Spectrometry Carbonaceous Chondrite Iron Meteorite Positive Aberration Clear Positive Correlation
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