CO2+O(1D) isotopic exchange: Laboratory and modeling studies

Johnston, Jeffrey C.; Röckmann, Thomas; Brenninkmeijer, Carl A. M.

doi:10.1029/2000jd900070

Cited by 32 publications

(55 citation statements)

References 57 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…), which is not significantly different from the KIE of 1.000 expected for statistical isotope exchange branching fractions and is quantitatively consistent with the results from the continuous irradiation experiments. Hence, our results are consistent with previous studies asserting that the O( 1 D)ϩCO 2 isotope exchange products are partitioned statistically (14,16,25). In contrast, a 13 C/ 12 C KIE of Ϸ1.01 would be required to explain the high-latitude isotopic correlations shown in Fig.…”

supporting

confidence: 93%

“…Stratospheric oxygen isotope covariations in CO 2 (8,11,12) consistently differ from those found in laboratory experiments simulating stratospheric photochemistry (6,(13)(14)(15)(16) Table 1). The stratospheric samples display ⌬ 47 values both higher and more variable than those exhibited by tropospheric air at the surface, which has an average ⌬ 47 value of 0.92 Ϯ 0.01‰ in remote regions (Cape Grim, Tasmania and Barrow, Alaska) (18).…”

mentioning

confidence: 55%

See 1 more Smart Citation

Large and unexpected enrichment in stratospheric ¹⁶ O ¹³ C ¹⁸ O and its meridional variation

Yeung¹,

Affek

Hoag³

et al. 2009

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

View full text Add to dashboard Cite

The stratospheric CO 2 oxygen isotope budget is thought to be governed primarily by the O( 1 D)+CO 2 isotope exchange reaction. However, there is increasing evidence that other important physical processes may be occurring that standard isotopic tools have been unable to identify. Measuring the distribution of the exceedingly rare CO 2 isotopologue 16 O 13 C 18 O, in concert with 18 O and 17 O abundances, provides sensitivities to these additional processes and, thus, is a valuable test of current models. We identify a large and unexpected meridional variation in stratospheric 16 O 13 C 18 O, observed as proportions in the polar vortex that are higher than in any naturally derived CO 2 sample to date. We show, through photochemical experiments, that lower 16 O 13 C 18 O proportions observed in the midlatitudes are determined primarily by the O( 1 D)+CO 2 isotope exchange reaction, which promotes a stochastic isotopologue distribution. In contrast, higher 16 O 13 C 18 O proportions in the polar vortex show correlations with long-lived stratospheric tracer and bulk isotope abundances opposite to those observed at midlatitudes and, thus, opposite to those easily explained by O( 1 D)+CO 2 . We believe the most plausible explanation for this meridional variation is either an unrecognized isotopic fractionation associated with the mesospheric photochemistry of CO 2 or temperature-dependent isotopic exchange on polar stratospheric clouds. Unraveling the ultimate source of stratospheric 16 O 13 C 18 O enrichments may impose additional isotopic constraints on biosphere–atmosphere carbon exchange, biosphere productivity, and their respective responses to climate change.

show abstract

supporting

confidence: 93%

mentioning

confidence: 55%

Large and unexpected enrichment in stratospheric ¹⁶ O ¹³ C ¹⁸ O and its meridional variation

Yeung¹,

Affek

Hoag³

et al. 2009

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

View full text Add to dashboard Cite

show abstract

“…This ozone was destroyed over hot Ni foil (90±5) • C and CO 2 was separated from the product oxygen cryogenically. The effect of the decomposition of O 3 on a Ni surface was investigated in detail by Johnston et al (2000). In their study the authors determined a slight enrichment in CO 2 from the decomposition of O 3 on Ni, which amounted to 2-3‰ for 17 …”

Section: Setup and Sample Treatmentmentioning

confidence: 99%

“…It was confirmed that an isotope exchange via O( 1 D) occurs and it was further concluded that an anomalous fractionation process is associated with the excited CO 3 intermediate, which contributes to the observed enrichments in CO 2 . The second set of experiments by Johnston et al (2000) started with mixtures of O 2 and CO 2 . Hg-pen ray lamp induced photolysis of O 2 was used to produce O 3 which upon photolysis yielded O( 1 D) to react with CO 2 .…”

Section: Introductionmentioning

confidence: 99%

Investigations of the photochemical isotope equilibrium between O2, CO2 and O3

2007

Self Cite

View full text Add to dashboard Cite

Abstract. Contrary to tropospheric CO 2 whose oxygen isotopic composition follows a standard mass dependent relationship, i.e. δ 17 O∼0.5 δ 18 O, stratospheric CO 2 is preferentially enriched in 17 O, leading to a strikingly different relation: δ 17 O∼1.7 δ 18 O. It has been shown repeatedly that the isotope anomaly is inherited from O 3 via photolytically produced O( 1 D) that undergoes isotope exchange with CO 2 and the anomaly may well serve as a tracer of stratospheric chemistry if details of the exchange mechanism are understood. We have studied the photochemical isotope equilibrium in UV-irradiated O 2 -CO 2 and O 3 -CO 2 mixtures to quantify the transfer of the anomaly from O 3 to CO 2 at room temperature. By following the time evolution of the oxygen isotopic compositions of CO 2 and O 2 under varying initial isotopic compositions of both, O 2 /O 3 and CO 2 , the isotope equilibria between the two reservoirs were determined. A very strong dependence of the isotope equilibrium on the O 2 /CO 2 -ratio was established. Equilibrium enrichments of 17 O and 18 O in CO 2 relative to O 2 diminish with increasing CO 2 content, and this reduction in the equilibrium enrichments does not follow a standard mass dependent relation. When molecular oxygen exceeds the amount of CO 2 by a factor of about 20, 17 O and 18 O in equilibrated CO 2 are enriched by (142±4)‰ and (146±4)‰, respectively, at room temperature and at a pressure of 225 hPa, independent of the initial isotopic compositions of CO 2 and O 2 or O 3 . From these findings we derive a simple and general relation between the starting isotopic compositions and amounts of O 2 and CO 2 and the observed slope in a three oxygen isotope diagram. Predictions from this relation are compared with published laboratory and atmospheric data.

show abstract

“…[ [Chakraborty and Bhattacharya, 2003;Johnston et al, 2000;Perri et al, 2003], and quantum chemical calculations of the reaction energetics, which hint to a small barrier below the energy of the transition state on the way to the reaction products.…”

Section: Introductionmentioning

confidence: 99%

Absence of isotope exchange in the reaction of N₂O + O(¹D) and the global Δ¹⁷O budget of nitrous oxide

Kaiser

Röckmann

2005

Geophysical Research Letters

View full text Add to dashboard Cite

show abstract

CO₂+O(¹D) isotopic exchange: Laboratory and modeling studies

Cited by 32 publications

References 57 publications

Large and unexpected enrichment in stratospheric ¹⁶ O ¹³ C ¹⁸ O and its meridional variation

Large and unexpected enrichment in stratospheric ¹⁶ O ¹³ C ¹⁸ O and its meridional variation

Investigations of the photochemical isotope equilibrium between O<sub>2</sub>, CO<sub>2</sub> and O<sub>3</sub>

Absence of isotope exchange in the reaction of N₂O + O(¹D) and the global Δ¹⁷O budget of nitrous oxide

Contact Info

Product

Resources

About

CO2+O(1D) isotopic exchange: Laboratory and modeling studies

Cited by 32 publications

References 57 publications

Large and unexpected enrichment in stratospheric 16 O 13 C 18 O and its meridional variation

Large and unexpected enrichment in stratospheric 16 O 13 C 18 O and its meridional variation

Investigations of the photochemical isotope equilibrium between O&lt;sub&gt;2&lt;/sub&gt;, CO&lt;sub&gt;2&lt;/sub&gt; and O&lt;sub&gt;3&lt;/sub&gt;

Absence of isotope exchange in the reaction of N2O + O(1D) and the global Δ17O budget of nitrous oxide

Contact Info

Product

Resources

About

CO₂+O(¹D) isotopic exchange: Laboratory and modeling studies

Large and unexpected enrichment in stratospheric ¹⁶ O ¹³ C ¹⁸ O and its meridional variation

Large and unexpected enrichment in stratospheric ¹⁶ O ¹³ C ¹⁸ O and its meridional variation

Investigations of the photochemical isotope equilibrium between O<sub>2</sub>, CO<sub>2</sub> and O<sub>3</sub>

Absence of isotope exchange in the reaction of N₂O + O(¹D) and the global Δ¹⁷O budget of nitrous oxide