Solar Nitrogen: Evidence for a Secular Increase in the Ratio of Nitrogen-15 to Nitrogen-14

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Science  11 Apr 1975:
Vol. 188, Issue 4184, pp. 162-164
DOI: 10.1126/science.188.4184.162


Solar wind nitrogen, implanted in lunar soil samples, exhibits isotopic variations that are related to the time, although not to the duration, of implantation, with earlier samples characterized by lower ratios of nitrogen-15 to nitrogen-14. An increase in the solar nitrogen-15 content during the lifetime of the lunar regolith is probably caused by spallation of oxygen-16 in the surface regions of the sun.