Temperature-dependent rate coefficient measurements for the reaction of bromine atoms with trichloroethene, ethene, acetylene, and tetrachloroethene in air

Ramacher, B.; Tyndall, Geoffrey S.

doi:10.1002/1097-4601(200103)33:3<198::aid-kin1014>3.0.co;2-z

Cited by 19 publications

(33 citation statements)

References 64 publications

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“… This corresponds to k = 1.08 × 10 −9 cm 3 molecule −1 s −1 at 240 K at the surface. The reaction Br + ethene exhibits a similar negative temperature dependence, and we again use the IUPAC recommended calculation method [ Atkinson et al , 1999] based on data first published by Ramacher et al [2001] and expressed as where B = 7.5 × 10 −12 ·[O 2 ]. This yields k = 2.02 × 10 −13 cm 3 molecule −1 s −1 at 240 K. Using these recommended equations, the ratio k Cl+ethene /k Br+ethene changes by a factor of two from 240 K to 298 K, indicating that the rate constant temperature corrections are necessary.…”

Section: Resultsmentioning

confidence: 99%

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Chlorine and bromine atom ratios in the springtime Arctic troposphere as determined from measurements of halogenated volatile organic compounds

Keil¹,

Shepson²

2006

J. Geophys. Res.

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[1] The concentrations of a suite of halogenated volatile organic compounds (HVOCs) were measured near Barrow, Alaska, from January to April 2005. The HVOCs are produced from the reaction of bromine and chlorine atoms with ethene and propene. During periods of decreasing ozone concentration, increases in the HVOC concentrations allowed for the calculation of the ratio of bromine to chlorine radical concentrations, based on available kinetic data. We use these concentration data to interrogate the chemistry that results in tropospheric ozone depletion in the Arctic, the possible sources of ozone depleting halogen molecules, and the spatial scale in which ozone depletion occurs. We report calculated halogen atom concentration ratios ([Br]/[Cl]) during partial ozone depletion events. The concentration ratio was observed to range from 80 ± 30 to 990 ± 300 when ozone concentrations were above 15 ppb. These data make it clear that chlorine and bromine atom chemistry is active in the Arctic troposphere beginning at twilight, even absent large-scale ozone depletion, and that the sources of the chlorine atoms are poorly understood.

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Section: Resultsmentioning

confidence: 99%

“…This corresponds to k = 1.08 Â 10 À9 cm 3 molecule À1 s À1 at 240 K at the surface. The reaction Br + ethene exhibits a similar negative temperature dependence, and we again use the IUPAC recommended calculation method [Atkinson et al, 1999] based on data first published by Ramacher et al [2001] and expressed as equation (8) where…”

Section: Resultsmentioning

confidence: 99%

Chlorine and bromine atom ratios in the springtime Arctic troposphere as determined from measurements of halogenated volatile organic compounds

Keil¹,

Shepson²

2006

J. Geophys. Res.

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“…It includes a detailed description of the oxidation of C 1 ‐C 6 hydrocarbons updated with recent developments [ Sander et al , 2000]. The rate constants for the reactions of Br with aldehydes [ Ramacher et al , 2000] and ethyne [ Ramacher et al , 2001] have been updated. Reactions of BrO with CH 2 O and HBr are not included, based on evidence that they are negligibly slow; even at the upper limits reported by Orlando et al [2000] we find that they have little effect on the evolution of O 3 depletion.…”

Section: Photochemical Modelmentioning

confidence: 99%

Coupled evolution of BrO_x‐ClO_x‐HO_x‐NO_x chemistry during bromine‐catalyzed ozone depletion events in the arctic boundary layer

et al. 2003

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[1] Extensive chemical characterization of ozone (O 3 ) depletion events in the Arctic boundary layer during the TOPSE aircraft mission in March-May 2000 enables analysis of the coupled chemical evolution of bromine (BrO x ), chlorine (ClO x ), hydrogen oxide (HO x ) and nitrogen oxide (NO x ) radicals during these events. We project the TOPSE observations onto an O 3 chemical coordinate to construct a chronology of radical chemistry during O 3 depletion events, and we compare this chronology to results from a photochemical model simulation. Comparison of observed trends in ethyne (oxidized by Br) and ethane (oxidized by Cl) indicates that ClO x chemistry is only active during the early stage of O 3 depletion (O 3 > 10 ppbv). We attribute this result to the suppression of BrCl regeneration as O 3 decreases. Formaldehyde and peroxy radical concentrations decline by factors of 4 and 2 respectively during O 3 depletion and we explain both trends on the basis of the reaction of CH 2 O with Br. Observed NO x concentrations decline abruptly in the early stages of O 3 depletion and recover as O 3 drops below 10 ppbv. We attribute the initial decline to BrNO 3 hydrolysis in aerosol, and the subsequent recovery to suppression of BrNO 3 formation as O 3 drops. Under halogen-free conditions we find that HNO 4 heterogeneous chemistry could provide a major NO x sink not included in standard models. Halogen radical chemistry in the model can produce under realistic conditions an oscillatory system with a period of 3 days, which we believe is the fastest oscillation ever reported for a chemical system in the atmosphere.

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“…Only a few rate coefficient measurements exist for each of these compound classes . Additions of Br‐atom to unsaturated VOCs (alkenes and alkynes) are complex processes, as the Br‐containing alkyl radical formed via addition typically decomposes to reactants on a timescale that is competitive with O 2 addition to form a peroxy radical . The effective reaction rate coefficients thus generally possess complex temperature, pressure, and O 2 partial pressure dependencies.…”

Section: Sars For Different Reaction Typesmentioning

confidence: 99%

Perspective on Mechanism Development and Structure‐Activity Relationships for Gas‐Phase Atmospheric Chemistry

Vereecken

Aumont

Barnes

et al. 2018

Int J of Chemical Kinetics

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This perspective gives our views on general aspects and future directions of gasphase atmospheric chemical kinetic mechanism development, emphasizing on the work needed for the sustainable development of chemically detailed mechanisms that reflect current kinetic, mechanistic, and theoretical knowledge. Current and future mechanism development efforts and research needs are discussed, including software-aided autogeneration and maintenance of kinetic models as a future-proof approach for atmospheric model development. There is an overarching need for the evaluation and extension of structure-activity relationships (SARs) that predict the properties and reactions of the many multifunctionalized compounds in the atmosphere that are at the core of detailed mechanisms, but for which no direct chemical data are available. Here, we discuss the experimental and theoretical data needed to support the development of mechanisms and SARs, the types of SARs relevant to atmospheric chemistry, the current status and limitations of SARs for various types of atmospheric reactions, the status of thermochemical estimates needed for mechanism development, and our outlook for the future. The authors have recently formed a SAR evaluation working group to address these issues. C

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Temperature-dependent rate coefficient measurements for the reaction of bromine atoms with trichloroethene, ethene, acetylene, and tetrachloroethene in air

Cited by 19 publications

References 64 publications

Chlorine and bromine atom ratios in the springtime Arctic troposphere as determined from measurements of halogenated volatile organic compounds

Chlorine and bromine atom ratios in the springtime Arctic troposphere as determined from measurements of halogenated volatile organic compounds

Coupled evolution of BrO_x‐ClO_x‐HO_x‐NO_x chemistry during bromine‐catalyzed ozone depletion events in the arctic boundary layer

Perspective on Mechanism Development and Structure‐Activity Relationships for Gas‐Phase Atmospheric Chemistry

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Temperature-dependent rate coefficient measurements for the reaction of bromine atoms with trichloroethene, ethene, acetylene, and tetrachloroethene in air

Cited by 19 publications

References 64 publications

Chlorine and bromine atom ratios in the springtime Arctic troposphere as determined from measurements of halogenated volatile organic compounds

Chlorine and bromine atom ratios in the springtime Arctic troposphere as determined from measurements of halogenated volatile organic compounds

Coupled evolution of BrOx‐ClOx‐HOx‐NOx chemistry during bromine‐catalyzed ozone depletion events in the arctic boundary layer

Perspective on Mechanism Development and Structure‐Activity Relationships for Gas‐Phase Atmospheric Chemistry

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Coupled evolution of BrO_x‐ClO_x‐HO_x‐NO_x chemistry during bromine‐catalyzed ozone depletion events in the arctic boundary layer