Isotope separation by carrier diffusion.
Nitrogen isotope fractionation in the Hoering-Moore experiment, injection of N2 into CO2 carrier and flow through sandstone, is due to diffusion in the gas phase rather than to surface interaction. This process, called "carrier diffusion," produces a characteristic fractionation pattern relative to a fraction coordinate, with points of zero fractionation at 16 and 84 percent and heavy isotope enrichment between these points. Carrier diffusion is an efficient enrichment process for low-abundance isotopes lighter than the abundant species and for helium and hydrogen in gas mixtures.
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