An analytical formulation of isotope fractionation due to self-shielding

Lyons, J. R.

doi:10.1016/j.gca.2020.05.001

Cited by 7 publications

(4 citation statements)

References 73 publications

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“…As mentioned in the Introduction, beside laboratory experiments, numerous mass independent isotopic effects have been observed in meteoritic minerals which are regarded as the first solids condensed during the formation of the solar system. For instance, the solar system variations in oxygen isotopes are interpreted as a self shielding effect [42,43,44] i.e. an isotopically selective photodissociation of CO.…”

Section: Discussionmentioning

confidence: 99%

Mass Independent Isotopic Fractionation: A Key to Plasma Chemistry

ROBERT¹,

Reinhardt²

2022

SSRN Journal

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Section: Discussionmentioning

confidence: 99%

Mass Independent Isotopic Fractionation: A Key to Plasma Chemistry

ROBERT¹,

Reinhardt²

2022

SSRN Journal

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“…Self-shielding and other photolysis isotope effects (56) are another means by which CO, one of the most common molecules in the universe, may obtain an O-MIF signature in interstellar clouds or in low-temperature regions of the solar nebula, which has been suggested ( 89) as an additional mechanism by which the most primitive meteorites could obtain their O-MIF signature, for example. Self-shielding may occur when an atmosphere or gas cloud becomes optically thick at the wavelengths that photodissociate the common isotopologue of a species (e.g., C 16 O) while the wavelengths that photodissociate the rare isotopologues (e.g., C 17 O and C 18 O) remain optically thin, which can induce O-MIF.…”

Section: O-mif In Species Independent Of Ozone Kies: Co and Siomentioning

confidence: 99%

Isotope Effects and the Atmosphere

Carlstad

Boering

2023

Annu. Rev. Phys. Chem.

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Chemical physics plays a large role in determining the isotopic compositions of gases in Earth's atmosphere, which in turn provide fundamental insights into the sources, sinks, and transformations of atmospheric gases and particulates and their influence on climate. This review focuses on the kinetic and photolysis isotope effects relevant to understanding the isotope compositions of atmospheric ozone, carbon dioxide, methane, nitrous oxide, and other gases and their historical context. The discussion includes non-mass-dependent isotope compositions of oxygen-containing species and a brief overview of the recent growth of clumped isotope measurements at natural isotopic abundances, that is, of molecules containing more than one rare isotope. The intention is to introduce chemistry researchers to the field of using isotope compositions as tracers of atmospheric chemistry and climate both today and back in time through ice and rock records and to highlight the outstanding research questions to which experimental and theoretical physical chemists can contribute. Expected final online publication date for the Annual Review of Physical Chemistry, Volume 74 is April 2023. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

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“…The question of the origin of the 1:1 CL is central to the formation of solids in the early solar system. It has been successively proposed to result from 1) the injection in the protosolar nebula (PSN) of pure 16 O of supernovae origin (3), 2) a mass-independent fractionation (MIF) effect analogous to those observed experimentally during the synthesis of ozone (1, 7), and 3) a self-shielding effect on the solar (or nonsolar) ultraviolet light by CO (12)(13)(14). While the lack of presolar grains enriched in 16 O makes the first proposal unlikely (15), the two other ones have gained some recent theoretical (14,16) or experimental (17,18) support.…”

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confidence: 99%

“…It has been successively proposed to result from 1) the injection in the protosolar nebula (PSN) of pure 16 O of supernovae origin (3), 2) a mass-independent fractionation (MIF) effect analogous to those observed experimentally during the synthesis of ozone (1, 7), and 3) a self-shielding effect on the solar (or nonsolar) ultraviolet light by CO (12)(13)(14). While the lack of presolar grains enriched in 16 O makes the first proposal unlikely (15), the two other ones have gained some recent theoretical (14,16) or experimental (17,18) support. In the present paper, we address experimentally several issues raised by the ozone experiment to explore whether this 1:1 CL could be due to MIFs reactions having taken place in the PSN.…”

mentioning

confidence: 99%

Oxygen and magnesium mass-independent isotopic fractionation induced by chemical reactions in plasma

Robert

Chaussidon

Gonzalez-Cano

et al. 2021

Proc. Natl. Acad. Sci. U.S.A.

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Enrichment or depletion ranging from −40 to +100% in the major isotopes 16O and 24Mg were observed experimentally in solids condensed from carbonaceous plasma composed of CO2/MgCl2/Pentanol or N2O/Pentanol for O and MgCl2/Pentanol for Mg. In NanoSims imaging, isotope effects appear as micrometer-size hotspots embedded in a carbonaceous matrix showing no isotope fractionation. For Mg, these hotspots are localized in carbonaceous grains, which show positive and negative isotopic effects so that the whole grain has a standard isotope composition. For O, no specific structure was observed at hotspot locations. These results suggest that MIF (mass-independent fractionation) effects can be induced by chemical reactions taking place in plasma. The close agreement between the slopes of the linear correlations observed between δ25Mg versus δ26Mg and between δ17O versus δ18O and the slopes calculated using the empirical MIF factor η discovered in ozone [M. H. Thiemens, J. E. Heidenreich, III. Science 219, 1073–1075; C. Janssen, J. Guenther, K. Mauersberger, D. Krankowsky. Phys. Chem. Chem. Phys. 3, 4718–4721] attests to the ubiquity of this process. Although the chemical reactants used in the present experiments cannot be directly transposed to the protosolar nebula, a similar MIF mechanism is proposed for oxygen isotopes: at high temperature, at the surface of grains, a mass-independent isotope exchange could have taken place between condensing oxides and oxygen atoms originated form the dissociation of CO or H2O gas.

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An analytical formulation of isotope fractionation due to self-shielding

Cited by 7 publications

References 73 publications

Mass Independent Isotopic Fractionation: A Key to Plasma Chemistry

Mass Independent Isotopic Fractionation: A Key to Plasma Chemistry

Isotope Effects and the Atmosphere

Oxygen and magnesium mass-independent isotopic fractionation induced by chemical reactions in plasma

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