Isotopic fractionation of Kr and Xe implanted in solids at very low energies

Bernatowicz, T. J.; Hagee, B. E.

doi:10.1016/0016-7037(87)90341-3

Cited by 22 publications

(15 citation statements)

References 11 publications

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“…In particular, kerogen-like materials produced when applying an electric discharge to an artificial gas mixture contained high concentrations of noble gases trapped in the formed carbon-rich films that displayed strong elemental fractionation from their reservoirs. As pointed out in other subsequent investigations, noble gases photoionization is indeed responsible for establishing the observed noble gas patterns in the synthetic products but the underlying physicochemical mechanisms remain still to be unveiled (Bernatowicz and Fahey, 1986;Bernatowicz and Hagee, 1987;Ponganis et al, 1997;Hohenberg et al, 2002;Marrocchi et al, 2011). In a recent experiment, Marrocchi et al (2011) evaporated kerogen and condensed it under ionizing conditions in a dilute xenon atmosphere, and observed a xenon isotopes enrichment of 1.3% u −1 in the carbon condensate, which is comparable to the fractionation factor of 1.1% u −1 expected here (Eqs.…”

Section: Trapping Of Ionized Noble Gases Into Organic Hazementioning

confidence: 95%

“…Processes able to fractionate the isotopes of xenon at such percent level require ionization of xenon (Frick et al, 1979;Bernatowicz and Fahey, 1986;Bernatowicz and Hagee, 1987;Ponganis et al, 1997;Hohenberg et al, 2002;Marrocchi et al, 2011). In experiments aimed at fractionating xenon isotopes upon ionization, ionized xenon is implanted into solids where it is enriched in heavy isotopes, whereas neutral xenon is much less efficiently trapped and is not isotopically fractionated.…”

Section: Constraints From Archean Noble Gas Isotopic Compositionmentioning

confidence: 98%

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Coupled noble gas–hydrocarbon evolution of the early Earth atmosphere upon solar UV irradiation

Hébrard

Marty

2014

Earth and Planetary Science Letters

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Using a new photochemical model of the Earth's early atmosphere, the relationship between noble gas photoionization and organic photochemistry has been investigated from the Archean eon to the present day. We have found that the enhanced UV emission of the young Sun triggered a peculiar atmospheric chemistry in a CH 4 -rich early atmosphere that resulted in the increased formation of an organic haze, similar to the preliminary results of a previous study (Ribas et al., 2010). We have investigated the interaction between this haze and noble gases photoionized by the UV light from the younger Sun. Laboratory experiments have shown indeed that ionized xenon trapping into organics (1) is more efficient that other ionized noble gases trapping and (2) results in a significant enrichment of heavy xenon isotopes relative to the light ones (e.g., Frick et al., 1979;Marrocchi et al., 2011). We find moreover preferential photoionization of xenon that peaks at an altitude range comparable to that of the organic haze formation, in contrast to other noble gases. Trapping and fractioning of ionized xenon in the organic haze could therefore have been far more efficient than for other noble gases, and could have been particularly effective throughout the Archean eon, since the UV irradiation flux from the young Sun was expected to be substantially higher than today (Ribas et al., 2010;Claire et al., 2012). Thus we suspect that the unique isotopic fractionation of atmospheric xenon and its elemental depletion in the atmosphere relative to other noble gases, compared to potential cosmochemical components, could have resulted from a preferential incorporation of the heaviest xenon isotopes into organics. A fraction of atmospheric xenon could have been continuously trapped in the forming haze and enriched in its heavy isotopes, while another fraction would have escaped from the atmosphere to space, with, or without isotope selection of the lightest isotopes. The combination of these two processes over long periods of time provides thereby a key process for explaining the evolution of its isotopic composition in the atmosphere over time that has been observed in Archean archives (Pujol et al., 2011).

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Section: Trapping Of Ionized Noble Gases Into Organic Hazementioning

confidence: 95%

Section: Constraints From Archean Noble Gas Isotopic Compositionmentioning

confidence: 98%

Coupled noble gas–hydrocarbon evolution of the early Earth atmosphere upon solar UV irradiation

Hébrard

Marty

2014

Earth and Planetary Science Letters

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“…This process has been modeled using cathodeless glow discharge at -100 eV (Bernatowicz and Hagee, 1987) and a modified Bayard-Alpert ion gauge (Bernatowicz and Fahey, 1986;Ponganis et al, 1997). Low-energy implantation alone is probably not a viable mechanism for the incorporation ofthe planetary gases into phase-Q because it occurs in a single exposed monolayer, limiting the concentration that can be achieved, and because there is no fundamental discrimination against similar incorporation of the light noble gases.…”

Section: Discussionmentioning

confidence: 99%

Active capture and anomalous adsorption: New mechanisms for the incorporation of heavy noble gases

Hohenberg¹,

Thonnard

Meshik³

2002

Meteorit & Planetary Scien

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Abstract-Active capture is a new process for the incorporation of large quantities of heavy noble gases into growing surfaces. Adsorption in the conventional sense involves surface bonding by polarization (Van der Waals forces). What is referred to as "anomalous adsorption" of heavy noble gases involves chemical bonds and can occur when other (more chemically active) species are not available to preempt sites with unfilled bonds. Anomalous adsorption has been observed under conditions of fracture, vacuum deposition and ionizing radiation. Active capture depends upon anomalous adsorption to retain noble gases on a surface long enough to be captured in a growing surface film as it is deposited. The fundamental principle may be the impingement onto the growing film with sufficient energy to liberate surface electrons (work function energy of a few electronvolts) so that they are retained by anomalous adsorption long enough to be entrapped in the growing surface. Trapping efficiencies of~I % have been observed for Kr and Xe in laboratory experiments, implying a fundamentally new mechanism for the incorporation of heavy noble gases onto surfaces. It may playa role in explaining the large concentrations of planetary noble gases contained in phase-Q.

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“…So, strong electric field such as lightning is needed for implantation. Bernatowicz and Hagee (1987) implanted Kr and Xe into tungsten under closed system condi tions at 50-500 eV and measured the fraction of gas trapped, calculated from the amount of trapped gas retrieved and the total of the trapped and gas phases. They reported that trapping gas increased with energy above 100 eV, whereas there was no significant difference in the level of gas trapping between the experiments at 50 eV and 100 eV.…”

Section: Trapping Efficiency Trapping Efficiencymentioning

confidence: 99%

Vapor-growth carbon and the origin of carbonaceous material in ureilites.

Fukunaga¹,

Matsuda²

1997

Geochem. J.

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We synthesized carbon products by the Modified Hot Filament Chemical Vapor Deposition (MHFCVD) method in an artificial atmosphere containing noble gases, and measured the noble gas abundances trapped in them. MHFCVD carbon synthesized at high voltage contained large amounts of noble gases enriched in heavy noble gases. The trapping efficiencies of noble gas were the highest among those reported for synthetic samples in laboratory experiments. The elemental abundance patterns are similar to those in Microwave Chemical Vapor Deposition (MWCVD) diamonds, but show severe depletions of Ne.Synthesized (MHFCVD) carbon samples have similar noble gas features to those in diamond-free ureilites. This result suggests that amorphous carbon in diamond-free ureilites was also formed by Chemical Vapor Deposition (CVD), and that noble gases were implanted into amorphous carbon as well as into diamond in ureilites under plasma conditions.

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Isotopic fractionation of Kr and Xe implanted in solids at very low energies

Cited by 22 publications

References 11 publications

Coupled noble gas–hydrocarbon evolution of the early Earth atmosphere upon solar UV irradiation

Coupled noble gas–hydrocarbon evolution of the early Earth atmosphere upon solar UV irradiation

Active capture and anomalous adsorption: New mechanisms for the incorporation of heavy noble gases

Vapor-growth carbon and the origin of carbonaceous material in ureilites.

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