Temperature dependence of ozone rate coefficients and isotopologue fractionation in 16O–18O oxygen mixtures

Janssen, Christof; Guenther, Juergen; Krankowsky, D.; Mauersberger, K.

doi:10.1016/s0009-2614(02)01665-2

Cited by 68 publications

(105 citation statements)

References 19 publications

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“…Using these results, we have formulated an empirical linear fit of the ␦ 18 O terminal and (26)(27)(28). Our estimates of the positional dependence of the 18 O enrichments are also in good agreement with other investigators (39). We conclude that although the overall isotopic enrichment is distributed throughout the ozone molecule, there is an anomalous excess in the terminal atoms.…”

Section: Resultssupporting

confidence: 84%

“…These findings should improve the photochemical modeling of ⌬ 17 O transfer reactions such as CO 2 ϩ O 1 D exchange (40,41) and NO x conversion to HNO 3 (16,36). We note, however, that most of the ⌬ 17 O values measured in tropospheric O 3 (12,14) fall outside their expected values based on temperature and pressure dependencies of formation (11,30,39,42 …”

Section: Resultsmentioning

confidence: 67%

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The role of symmetry in the mass independent isotope effect in ozone

Michalski

Bhattacharya

2009

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

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Understanding the internal distribution of ''anomalous'' isotope enrichments has important implications for validating theoretical postulates on the origin of these enrichments in molecules such as ozone and for understanding the transfer of these enrichments to other compounds in the atmosphere via mass transfer. Here, we present an approach, using the reaction NO 2 ؊ ؉ O3, for assessing the internal distribution of the (7) and non-mass-dependent (NOMAD) (8, 9).The most thoroughly studied MIF system is that of ozone formation. Ozone generated by electric discharge or UV photolysis can produce ⌬ 17 O values of 30-40‰ (‰ ϭ parts per thousand). There have also been numerous studies that have experimentally quantified the pressure and temperature dependence of the isotopic enrichments (10, 11). Most recently, the transfer of the ⌬ 17 O anomaly from ozone to other compounds during oxidation reactions (via atom transfer, e.g., mass balance) has been used to elucidate chemical oxidation pathways in modern atmospheres (16-21). These include ⌬ 17 O observations in atmospheric nitrate, sulfate, CO 2 , and N 2 O. ⌬ 17 O variations in atmospheric nitrate and sulfate are intriguing because they have opened the possibility of using these ⌬ 17 O variations in ice cores as a proxy for paleo-oxidation chemistry (22,23). Modeling such transfer reactions, however, requires knowledge of the internal distribution of the ⌬ 17 O anomaly, i.e., how much is contained in the central versus terminal atoms of ozone, because many atmospheric oxidations are thought to occur through terminal-only transition states.Theories as to the origin of the MIF effect have taken many turns (7,8,24,25), and some theories seem more adept at handling specific experimental cases than others. Most have symmetry as the main, albeit ad hoc, causal mechanism for producing MIF. Recent work by Marcus and coworkers (26-28) is perhaps the most thorough treatment, and they have suggested that nonstatistical RRKM effects arise because of differences in the rovibronic coupling efficiency of the asymmetric molecule when compared with the symmetric isomer. Recent NO 2 spectroscopic data appear to bear the theory out (29), but the uncertainties in that study remain significant, and no mass spectrometer isotope data on the unimolecular decay of NO 2 are available. Because the basis of the ozone MIF theory is symmetry driven, it is implied that the anomalous enrichment must be contained in the terminal atoms of ozone. To be clear, there maybe overall isotopic enrichment (␦ 18 O, ␦ 17 O) distributed throughout the molecule based on isotopologue zero-point energy differences (30), but the 17 O excess (⌬ 17 O) is expected to be only in the terminal position. Others, however, have argued against the symmetry theory (31-33) and have placed anomalous enrichments, even negative ⌬ 17 O values (34), throughout ozone in an attempt to reconcile experimental observations. Precise and accurate measurements of ozone's ⌬ 17 O internal distribution is therefore needed to test the symmet...

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Section: Resultssupporting

confidence: 84%

Section: Resultsmentioning

confidence: 67%

The role of symmetry in the mass independent isotope effect in ozone

Michalski

Bhattacharya

2009

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

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“…One feature not discussed thus far is the effect of temperature on the MIF (56,57). In treating an effect of temperature on the recombination rate for the O + O 2 reaction Troe introduced a chaperon mechanism (29,30,58), in addition to the energy transfer mechanism, the importance of the chaperon component increasing with decreasing temperature.…”

Section: Classical Semiclassical and Quantum Intramolecular Dynamicsmentioning

confidence: 99%

Theory of mass-independent fractionation of isotopes, phase space accessibility, and a role of isotopic symmetry

Marcus

2013

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

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Key experimental and theoretical features of mass-independent fractionation (MIF) of isotopes, also known as the η-effect, are summarized, including its difference from the exit channel zero-point energy difference effect. The latter exactly cancels in the MIF. One key experimental result is that the MIF for O 3 formation is a low-pressure phenomenon and, moreover, that it decreases with increasing pressure of third bodies at pressures far below the “Lindemann fall-off” pressur e s for three-body recombination of O and O 2 . A possible origin of the MIF is discussed in terms of a role for isotopologue symmetry in intramolecular energy sharing. An explanation is suggested for the large difference in the fall-off pressure for recombination and the pressure for a large decrease in MIF, in terms of a difference between deactivating collisions and what we term here “symmetry-changing collisions”. It is noted that the theory of the MIF involves four recombination rate constants and an equilibrium constant, for each trace isotope, seven rate constants in all and two equilibrium constants. A conceptual shortcut is noted. Experimental and computational information that may provide added insight into the MIF mechanism and tests is described.

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“…2 This study, C1 observations (10-12 km). Letters denote the estimates derived using the data from Bhattacharya et al (2008) and assuming only terminal (T), only central (C) and equiprobable terminal and central (TC) O 3 atoms transfer to the artefact CO. 3 Calculated using the laboratory KIE temperature dependence data summarised by Janssen et al (2003). 4 Calculated assuming a pressure dependence of the O 3 formation KIE similar to that measured at 320 K (see Guenther et al (1999) and refs.…”

Section: Estimate Of δ 18 O(o 3 )mentioning

confidence: 99%

“…The terminal O atoms in O 3 are enriched with respect to the molecular (bulk) O 3 composition when the latter is above +70 ‰ in δ 18 O (Janssen, 2005;Bhattacharya et al, 2008), therefore an incorporation of only central O atoms into the artefact CO molecules should result in a reduced apparent δ 18 O(CO c ) value. Such exclusive selection is, however, less likely from the kinetic standpoint and was not observed in available laboratory studies (see Savarino et al (2008) for a review).…”

Section: Estimate Of δ 18 O(o 3 )mentioning

confidence: 99%

An estimation of the <sup>18</sup>O / <sup>16</sup>O ratio of UT/LMS ozone based on artefact CO in air sampled during CARIBIC flights

Gromov

Brenninkmeijer

2015

Atmos. Chem. Phys.

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Abstract. An issue of O 3 -driven artefact production of O 3 in the upper troposphere/lowermost stratosphere (UT/LMS) air analysed in the CARIBIC-1 project is being discussed. By confronting the CO mixing and isotope ratios obtained from different analytical instrumentation, we (i) reject natural/artificial sampling and mixing effects as possible culprits of the problem, (ii) ascertain the chemical nature and quantify the strength of the contamination, and (iii) demonstrate successful application of the isotope mass-balance calculations for inferring the isotope composition of the contamination source. The δ 18 O values of the latter indicate that the oxygen is very likely being inherited from O 3 . The δ 13 C values hint at reactions of trace amounts of organics with stratospheric O 3 that could have yielded the artificial CO. While the exact contamination mechanism is not known, it is clear that the issue pertains only to the earlier (first) phase of the CARIBIC (Civil Aircraft for the Regular Investigation of the atmosphere Based on an Instrument Container) project. Finally, estimated UT/LMS ozone δ 18 O values are lower than those observed in the stratosphere within the same temperature range, suggesting that higher pressures (240-270 hPa) imply lower isotope fractionation controlling the local δ 18 O(O 3 ) value.

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Temperature dependence of ozone rate coefficients and isotopologue fractionation in 16O–18O oxygen mixtures

Cited by 68 publications

References 19 publications

The role of symmetry in the mass independent isotope effect in ozone

The role of symmetry in the mass independent isotope effect in ozone

Theory of mass-independent fractionation of isotopes, phase space accessibility, and a role of isotopic symmetry

An estimation of the <sup>18</sup>O / <sup>16</sup>O ratio of UT/LMS ozone based on artefact CO in air sampled during CARIBIC flights

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Temperature dependence of ozone rate coefficients and isotopologue fractionation in 16O–18O oxygen mixtures

Cited by 68 publications

References 19 publications

The role of symmetry in the mass independent isotope effect in ozone

The role of symmetry in the mass independent isotope effect in ozone

Theory of mass-independent fractionation of isotopes, phase space accessibility, and a role of isotopic symmetry

An estimation of the &lt;sup&gt;18&lt;/sup&gt;O / &lt;sup&gt;16&lt;/sup&gt;O ratio of UT/LMS ozone based on artefact CO in air sampled during CARIBIC flights

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An estimation of the <sup>18</sup>O / <sup>16</sup>O ratio of UT/LMS ozone based on artefact CO in air sampled during CARIBIC flights