Rapid photochemical equilibration of isotope bond ordering in O<sub>2</sub>

Yeung, Laurence Y.; Ash, Jeanine L.; Young, Edward

doi:10.1002/2014jd021909

Cited by 23 publications

(39 citation statements)

References 50 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…The model that most closely matches our experimental findings is the PIMC model presented by Webb and Miller (2014). If we use our experimental products as a reference frame (following the reasoning behind the clumped isotope absolute reference frames for CO 2 , CH 4 , N 2 O and O 2 (Eiler and Schauble, 2004;Yeung et al, 2014;Stolper et al, 2014)), we can calculate the hydrogen isotope structure of CITP-1: δD central_SMOW = -208.3±6.6‰ and δD terminal_SMOW = -169.2±3.5‰ and = -47.1±8.9‰.…”

Section: Position-specific Hydrogen Isotope Fractionation At Thermodysupporting

confidence: 64%

“…We use this calibration to test the validity of prior published theoretical predictions. Comparison of data with models suggest the most sophisticated of these discrepant models (Webb and Miller, 2014) is most accurate; this conclusion implies that there is a combined experimental and theoretical foundation for an 'absolute reference frame' for positionspecific H isotope analysis of propane, following principles previously used for clumped isotope analysis of CO 2 , CH 4 and O 2 (Eiler and Schauble, 2004;Yeung et al, 2014;Stolper et al, 2014). …”

mentioning

confidence: 80%

See 1 more Smart Citation

Position-specific hydrogen isotope equilibrium in propane

Xie

Ponton

Formolo

et al. 2018

Geochimica et Cosmochimica Acta

View full text Add to dashboard Cite

Intramolecular isotope distributions can constrain source attribution, mechanisms of formation and destruction, and temperature-time histories of molecules. In this study, we explore the D/H fractionation between central (-CH 2 -) and terminal (-CH 3 ) positions of propane (C 3 H 8 ) -a percent level component of natural gases. The temperature dependence of position-specific D/H fractionation of propane could potentially work as a geo-thermometer for natural gas systems, and a forensic identifier of specific thermogenic sources of atmospheric or aquatic emissions. Moreover, kinetically controlled departures from temperature dependent equilibrium might constrain mechanisms of thermogenic production, or provide indicators of biological or photochemical destruction. We developed a method to measure position-specific D/H differences of propane with high-resolution gas source mass spectrometry. We performed laboratory exchange experiments to study the exchange rates for both terminal and central positions, and used catalysts to drive the hydrogen isotope distribution of propane to thermodynamic equilibrium. Experimental results demonstrate that D/H exchange between propane and water happens easily in the presence of either Pd catalyst or Ni catalyst. Exchange rates are similar between the two positions catalyzed by Pd. However, the central position exchanges 2.2 times faster than the terminal position in the presence of Ni catalyst. At 200°C in the presence of Pd catalyst, the e-folding time of propane-water exchange is 20 days and of homogeneous exchange (i.e., equilibrium between central and terminal positions) is 28 minutes. An equilibrated (bracketed and time-invariant) intramolecular hydrogen isotope distribution was attained for propane at three temperatures, 30°C, 100°C and 200°C; these data serve as an initial experimental calibration of a new position-specific thermometer with a temperature sensitivity of 0.25‰ per ˚C at 100 ˚C. We use this calibration to test the validity of prior published theoretical predictions. Comparison of data with models suggest the most sophisticated of these discrepant models (Webb and Miller, 2014) is most accurate; this conclusion implies that there is a combined experimental and theoretical foundation for an 'absolute reference frame' for positionspecific H isotope analysis of propane, following principles previously used for clumped isotope analysis of CO 2 , CH 4 and O 2 (Eiler and Schauble, 2004;Yeung et al., 2014;Stolper et al., 2014).

show abstract

Section: Position-specific Hydrogen Isotope Fractionation At Thermodysupporting

confidence: 64%

mentioning

confidence: 80%

Position-specific hydrogen isotope equilibrium in propane

Xie

Ponton

Formolo

et al. 2018

Geochimica et Cosmochimica Acta

View full text Add to dashboard Cite

show abstract

“…In most other isotopic systems where the measurement of clumped isotopologues has been reported (CO 2 , carbonate, O 2 and methane), equilibrium exchange reactions comparable with those reviewed above form the basis for both calibrated geothermometers and an absolute reference frame for reporting clumped species . It is likely that the major natural processes that form N 2 O do not permit attainment of homogeneous equilibrium with respect to the proportions of isotopologues.…”

Section: Systematics Of Clumped and Position‐specific Isotope Effectsmentioning

confidence: 96%

Measurement of rare isotopologues of nitrous oxide by high‐resolution multi‐collector mass spectrometry

Magyar

Orphan

Eiler

2016

Rapid Comm Mass Spectrometry

View full text Add to dashboard Cite

show abstract

“…In the stratosphere, O 3 photochemistry rearranges the isotopes in O 2 on timescales of months or less toward Δ 36 ≥ 2.3‰, corresponding to stratospheric temperatures below ~240 K [ Yeung et al ., , ]. In the troposphere, O 3 photochemistry rearranges isotopes in O 2 as well, but orders of magnitude more slowly and at warmer temperatures (Figure b).…”

Section: Introductionmentioning

confidence: 99%

Isotopic ordering in atmospheric O₂ as a tracer of ozone photochemistry and the tropical atmosphere

et al. 2016

Self Cite

View full text Add to dashboard Cite

The distribution of isotopes within O2 molecules can be rapidly altered when they react with atomic oxygen. This mechanism is globally important: while other contributions to the global budget of O2 impart isotopic signatures, the O(3P) + O2 reaction resets all such signatures in the atmosphere on subdecadal timescales. Consequently, the isotopic distribution within O2 is determined by O3 photochemistry and the circulation patterns that control where that photochemistry occurs. The variability of isotopic ordering in O2 has not been established, however. We present new measurements of 18O18O in air (reported as Δ36 values) from the surface to 33 km altitude. They confirm the basic features of the clumped‐isotope budget of O2: Stratospheric air has higher Δ36 values than tropospheric air (i.e., more 18O18O), reflecting colder temperatures and fast photochemical cycling of O3. Lower Δ36 values in the troposphere arise from photochemistry at warmer temperatures balanced by the influx of high‐Δ36 air from the stratosphere. These observations agree with predictions derived from the GEOS‐Chem chemical transport model, which provides additional insight. We find a link between tropical circulation patterns and regions where Δ36 values are reset in the troposphere. The dynamics of these regions influences lapse rates, vertical and horizontal patterns of O2 reordering, and thus the isotopic distribution toward which O2 is driven in the troposphere. Temporal variations in Δ36 values at the surface should therefore reflect changes in tropospheric temperatures, photochemistry, and circulation. Our results suggest that the tropospheric O3 burden has remained within a ±10% range since 1978.

show abstract

Rapid photochemical equilibration of isotope bond ordering in O₂

Abstract: Abstract

Cited by 23 publications

References 50 publications

Position-specific hydrogen isotope equilibrium in propane

Position-specific hydrogen isotope equilibrium in propane

Measurement of rare isotopologues of nitrous oxide by high‐resolution multi‐collector mass spectrometry

Isotopic ordering in atmospheric O₂ as a tracer of ozone photochemistry and the tropical atmosphere

Contact Info

Product

Resources

About

Rapid photochemical equilibration of isotope bond ordering in O2

Abstract: Abstract

Cited by 23 publications

References 50 publications

Position-specific hydrogen isotope equilibrium in propane

Position-specific hydrogen isotope equilibrium in propane

Measurement of rare isotopologues of nitrous oxide by high‐resolution multi‐collector mass spectrometry

Isotopic ordering in atmospheric O2 as a tracer of ozone photochemistry and the tropical atmosphere

Contact Info

Product

Resources

About

Rapid photochemical equilibration of isotope bond ordering in O₂

Isotopic ordering in atmospheric O₂ as a tracer of ozone photochemistry and the tropical atmosphere