The non-mass-dependent oxygen isotope effect in the electrodissociation of carbon dioxide: A step toward understanding NoMaD chemistry |
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Authors: | JE Heidenreich MH Thiemens |
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Institution: | Department of Chemistry, B-017, University of California, San Diego, La Jolla, California 92093 USA |
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Abstract: | A non-mass dependent (NoMaD) oxygen isotope effect is demonstrated in the dissociation of CO2 similar to that observed in the electrosynthesis of ozone. The molecular oxygen produced carries the signature of two separate isotopic fractionation processes; a mass-dependent fractionation probably due to CO2 + O isotopic exchange, and a secondary NoMaD fractionation (δ17O = 0.97 ± 0.09δ18O, with the O2 depleted in 17O and 18O). It is suggested that the effect is due to either the formation or relaxation of ozone in an excited electronic state. This represents the latest advance in the understanding of chemical NoMaD effects which may be essential to the explanation of non-mass-dependent fractionations observed in meteorites. |
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