Determination of Atmospheric Lifetimes via the Measurement of OH Radical Kinetics

Kurylo, Michael J.; Orkin, Vladimir L.

doi:10.1021/cr020524c

Cited by 113 publications

(100 citation statements)

References 195 publications

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“…For each set of experiments, the difference between the value of k 0 directly measured in the absence of bromine and k 0 found from the zero-abscissa intercept of the least-squares straight line in the ([Br 2 ], k′) coordinates was within the experimental uncertainties (2σ level of statistical uncertainties obtained from the linear least-squares-fits). We analyzed the possible effect of a minor deviation from the first-order kinetic behavior of the OH background loss on the measurement of k 1 values using data processing with the background-loss correction described in references 10, [16][17][18][19]. Under all the experimental conditions in our study, it was found that this effect was very small (less than 0.8% of k 1 value) such that no background-loss correction was necessary.…”

Section: B Reaction Rate Measurements and Resultsmentioning

confidence: 92%

Kinetic Study of the Gas-Phase Reaction of OH with Br₂

2006

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An experimental, temperature-dependent kinetic study of the gas-phase reaction of the hydroxyl radical with molecular bromine (reaction 1) has been performed using a pulsed laser photolysis/ pulsed-laser-induced fluorescence technique over a wide temperature range of 297 -766 K, and at pressures between 6.68 and 40.29 kPa of helium. The experimental rate coefficients for reaction 1 demonstrate no correlation with pressure and exhibit a negative temperature dependence with a slight negative curvature in the Arrhenius plot. A non-linear least-squares fit with two floating parameters of the temperature dependent k 1 (T) data set using an equation of the form k 1 (T) = AT n yields the recommended expression k 1 (T) = 1.85×10 −9 T − 0.66 cm 3 molecule −1 s −1 for the temperature dependence of the reaction 1 rate coefficient. The potential energy surface (PES) of reaction 1 was investigated using quantum chemistry methods. The reaction proceeds through formation of a weakly bound OH···Br 2 complex and a PES saddle point with an energy below that of the reactants. Temperature dependence of the reaction rate coefficient was modeled using the RRKM method on the basis of the calculated PES.

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Section: B Reaction Rate Measurements and Resultsmentioning

confidence: 92%

Kinetic Study of the Gas-Phase Reaction of OH with Br₂

2006

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“…The curvature of the Arrhenius plot has been well documented to occur for numerous elementary reactions of OH radical 26,35 . A modified, three-parameter Arrhenius expression is frequently used to describe the temperature dependence for reactions with smaller deviation from linearity, such as the reactions of OH with HFCs 36 and fluoro alcohols 37 .…”

Section: Kinetics Of the Reaction Of Oh Radical With Acetyl Fluoridementioning

confidence: 99%

Experimental and Theoretical Study on the OH-Reaction Kinetics and Photochemistry of Acetyl Fluoride (CH₃C(O)F), an Atmospheric Degradation Intermediate of HFC-161 (C₂H₅F)

Song

Zügner

et al. 2015

J. Phys. Chem. A

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ABSTRACT:The direct reaction kinetic method of low pressure fast discharge flow (DF) with resonance fluorescence monitoring of OH (RF) has been applied to determine rate coefficients for the overall reactions OH + C 2 H 5 F (EtF) (1) and OH + CH 3 C(O)F (AcF) (2). Acetyl fluoride reacts slowly with the hydroxyl radical, the rate coefficient at laboratory temperature is k2 (300 K) = (0.74 ± 0.05) × 10 -14 cm 3 molecule -1 s -1 (given with 2σ statistical uncertainty). The temperature dependence of the reaction does not obey the Arrhenius law and it is described well by the two-exponential rate expression of k 2 (300-410 K) = 3.60 × 10 -3 exp(-10500 / T) + 1.56 × 10 -13 exp(-910 / T) cm 3 molecule -1 s -1 . The rate coefficient of k 1 = (1.90 ± 0.19) × 10 -13 cm 3 molecule -1 s -1 has been determined for the EtF-reaction at room temperature (T = 298 K).Microscopic mechanisms for the OH + CH 3 C(O)F reaction have also been studied theoretically using the ab initio CBS-QB3 an G4 methods. Variational transition state theory was employed to obtain rate coefficients for the OH + CH 3 C(O)F reaction as a function of temperature on the basis of the ab initio data. The calculated rate coefficients are in good agreement with the experimental data. It is revealed that the reaction takes place predominantly via the indirect H-abstraction mechanism involving H-bonded prereactive complexes and forming the nascent products of H 2 O and the CH 2 CFO radical. The nonArrhenius behavior of the rate coefficient at temperatures below 500 K is ascribed to the significant tunneling effect of the in-the-plane H-abstraction dynamic bottleneck. The production of FC(O)OH + CH 3 via the addition/elimination mechanism is hardly competitive due to the significant barriers along the reaction routes.Photochemical experiments of AcF were performed at 248 nm by using exciplex lasers. The total photodissociation quantum yield for CH 3 C(O)F has been found significantly less than unity; among the primary photochemical processes, C-C bond cleavage is by far dominating compared with CO-elimination. The absorption spectrum of AcF has also been determined displaying a strong blue shift compared with the spectra of aliphatic carbonyls.Consequences of the results on atmospheric chemistry have been discussed.3

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“…(2003))] are the lifetimes of a given compound and MCF, respectively, due to the reactions with hydroxyl radical in the troposphere only. k OH (272K) and (272 ) MCF OH kK = 6.0x10 -15 cm 3 molecule -1 s -1 (Kurylo & Orkin, 2003) are the rate constants for the reactions of these compounds with OH at 272K. The use of 272K in place of 298K overcomes the problems associated with the use of temperature dependent OH reaction and the errors are minimized compared to estimates using 298K.…”

Section: Segregated and No Segregated Hfesmentioning

confidence: 99%

“…To provide an accurate evaluation of the global warming potentials, the lifetimes must first be obtained. The atmospheric lifetimes of pollutants is generally calculated on the basis of the reaction rates with OH only (Kurylo & Orkin, 2003), assuming that the reaction rates are independent of temperature. This is not suitable for chemicals with low reactivity.…”

Section: Introductionmentioning

confidence: 99%

Contribution of the Atmospheric Chlorine Reactions to the Degradation of Greenhouse Gases: CFCs Substitutes

Bravo¹,

Díaz-de-Mera²,

Aranda³

et al. 2011

Planet Earth 2011 - Global Warming Challenges and Opportunities for Policy and Practice

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Determination of Atmospheric Lifetimes via the Measurement of OH Radical Kinetics

Cited by 113 publications

References 195 publications

Kinetic Study of the Gas-Phase Reaction of OH with Br₂

Kinetic Study of the Gas-Phase Reaction of OH with Br₂

Experimental and Theoretical Study on the OH-Reaction Kinetics and Photochemistry of Acetyl Fluoride (CH₃C(O)F), an Atmospheric Degradation Intermediate of HFC-161 (C₂H₅F)

Contribution of the Atmospheric Chlorine Reactions to the Degradation of Greenhouse Gases: CFCs Substitutes

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Determination of Atmospheric Lifetimes via the Measurement of OH Radical Kinetics

Cited by 113 publications

References 195 publications

Kinetic Study of the Gas-Phase Reaction of OH with Br2

Kinetic Study of the Gas-Phase Reaction of OH with Br2

Experimental and Theoretical Study on the OH-Reaction Kinetics and Photochemistry of Acetyl Fluoride (CH3C(O)F), an Atmospheric Degradation Intermediate of HFC-161 (C2H5F)

Contribution of the Atmospheric Chlorine Reactions to the Degradation of Greenhouse Gases: CFCs Substitutes

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Kinetic Study of the Gas-Phase Reaction of OH with Br₂

Kinetic Study of the Gas-Phase Reaction of OH with Br₂

Experimental and Theoretical Study on the OH-Reaction Kinetics and Photochemistry of Acetyl Fluoride (CH₃C(O)F), an Atmospheric Degradation Intermediate of HFC-161 (C₂H₅F)