Kinetics of the reactions of hydroxyl radicals with aliphatic ethers studied under simulated atmospheric conditions: Temperature dependences of the rate coefficients

1990 ◽  
Vol 10 (1) ◽  
pp. 27-38 ◽  
Author(s):  
Paul J. Bennett ◽  
J. Alistair Kerr
Keyword(s):  
Hydroxyl Radicals ◽  
Rate Coefficients ◽  
Atmospheric Conditions ◽  
Temperature Dependences ◽  
Kinetics Of ◽  
Aliphatic Ethers

scholarly journals Kinetics of the OH + NO<sub>2</sub> reaction: rate coefficients (217–333 K, 16–1200 mbar) and fall-off parameters for N<sub>2</sub> and O<sub>2</sub> bath gases

2019 ◽  
Vol 19 (16) ◽  
pp. 10643-10657 ◽  
Author(s):  
Damien Amedro ◽  
Arne J. C. Bunkan ◽  
Matias Berasategui ◽  
John N. Crowley
Keyword(s):  
Pressure Range ◽  
Great Influence ◽  
Rate Coefficients ◽  
Atmospheric Conditions ◽  
Collision Efficiency ◽  
Title Reaction ◽  
Temperature And Pressure ◽  
Kinetics Of ◽  
Lower Collision

Abstract. The radical terminating, termolecular reaction between OH and NO2 exerts great influence on the NOy∕NOx ratio and O3 formation in the atmosphere. Evaluation panels (IUPAC and NASA) recommend rate coefficients for this reaction that disagree by as much as a factor of 1.6 at low temperature and pressure. In this work, the title reaction was studied by pulsed laser photolysis and laser-induced fluorescence over the pressure range 16–1200 mbar and temperature range 217–333 K in N2 bath gas, with experiments at 295 K (67–333 mbar) for O2. In situ measurement of NO2 using two optical absorption set-ups enabled generation of highly precise, accurate rate coefficients in the fall-off pressure range, appropriate for atmospheric conditions. We found, in agreement with previous work, that O2 bath gas has a lower collision efficiency than N2 with a relative collision efficiency to N2 of 0.74. Using the Troe-type formulation for termolecular reactions we present a new set of parameters with k0(N2) = 2.6×10-30 cm6 molecule−2 s−1, k0(O2) = 2.0×10-30 cm6 molecule−2 s−1, m=3.6, k∞=6.3×10-11 cm3 molecule−1 s−1, and Fc=0.39 and compare our results to previous studies in N2 and O2 bath gases.

Kinetics of the unimolecular reaction of CH2OO and the bimolecular reactions with the water monomer, acetaldehyde and acetone under atmospheric conditions

2015 ◽  
Vol 17 (30) ◽  
pp. 19862-19873 ◽  
Author(s):  
Torsten Berndt ◽  
Ralf Kaethner ◽  
Jens Voigtländer ◽  
Frank Stratmann ◽  
Mark Pfeifle ◽  
...  
Keyword(s):  
Rate Coefficients ◽  
Unimolecular Reaction ◽  
Atmospheric Conditions ◽  
Bimolecular Reactions ◽  
Kinetics Of

The rate coefficients of the unimolecular reaction of CH2OO and the bimolecular reactions with the water monomer and carbonyls were measured.

scholarly journals Database for the kinetics of the gas-phase atmospheric reactions of organic compounds

2020 ◽  
Author(s):  
Max R. McGillen ◽  
William P.L. Carter ◽  
Abdelwahid Mellouki ◽  
John J. Orlando ◽  
Bénédicte Picquet-Varrault ◽  
...  
Keyword(s):  
Gas Phase ◽  
Organic Compounds ◽  
Degradation Products ◽  
Rate Coefficients ◽  
Training Dataset ◽  
Gas Phase Reactions ◽  
Atmospheric Reactions ◽  
Temperature Dependences ◽  
Potential Applications ◽  
Kinetics Of

Abstract. We present a digital, freely available, searchable and evaluated compilation of rate coefficients for the gas-phase reactions of organic compounds with OH, Cl and NO3 radicals and with O3 (McGillen et al., 2019). Although other compilations of much of these data exist, many are out-of-date, most have limited scope, and all are difficult to search and to load completely into a digitized form. This compilation uses results of previous reviews, though many recommendations are updated to incorporate new or omitted data or address errors, and includes recommendations on many reactions that have not been reviewed previously. The database, which incorporates over 50 years of measurements, consists of a total of 2765 recommended bimolecular rate coefficients for the reactions of 1357 organic substances with OH, 709 with Cl, 310 with O3, and 389 with NO3, and is much larger than previous compilations. A large variety of functional groups is present in this database, including naturally occurring chemicals formed in or emitted to the atmosphere and anthropogenic compounds such as halocarbons and their degradation products. Recommendations were made for rate coefficients at 298 K and, where possible, the temperature dependences over the entire range of the available data. The primary motivation behind this project has been to provide a large and thoroughly evaluated training dataset for the development of structure-activity relationships (SARs), whose reliability depends fundamentally upon the availability of high-quality experimental data. However, there are other potential applications of this work, such as research related to atmospheric lifetimes and fates of organic compounds, or modelling gas-phase reactions of organics in various environments. This database is freely accessible at https://doi.org/10.25326/36 (McGillen et al., 2019).

scholarly journals Database for the kinetics of the gas-phase atmospheric reactions of organic compounds

2020 ◽  
Vol 12 (2) ◽  
pp. 1203-1216 ◽  
Author(s):  
Max R. McGillen ◽  
William P. L. Carter ◽  
Abdelwahid Mellouki ◽  
John J. Orlando ◽  
Bénédicte Picquet-Varrault ◽  
...  
Keyword(s):  
Gas Phase ◽  
Organic Compounds ◽  
Degradation Products ◽  
Rate Coefficients ◽  
Training Dataset ◽  
Gas Phase Reactions ◽  
Atmospheric Reactions ◽  
Temperature Dependences ◽  
Potential Applications ◽  
Kinetics Of

Abstract. We present a digital, freely available, searchable, and evaluated compilation of rate coefficients for the gas-phase reactions of organic compounds with OH, Cl, and NO3 radicals and with O3. Although other compilations of many of these data exist, many are out of date, most have limited scope, and all are difficult to search and to load completely into a digitized form. This compilation uses results of previous reviews, though many recommendations are updated to incorporate new or omitted data or address errors, and includes recommendations on many reactions that have not been reviewed previously. The database, which incorporates over 50 years of measurements, consists of a total of 2765 recommended bimolecular rate coefficients for the reactions of 1357 organic substances with OH, 709 with Cl, 310 with O3, and 389 with NO3, and is much larger than previous compilations. Many compound types are present in this database, including naturally occurring chemicals formed in or emitted to the atmosphere and anthropogenic compounds such as halocarbons and their degradation products. Recommendations are made for rate coefficients at 298 K and, where possible, the temperature dependences over the entire range of the available data. The primary motivation behind this project has been to provide a large and thoroughly evaluated training dataset for the development of structure–activity relationships (SARs), whose reliability depends fundamentally upon the availability of high-quality experimental data. However, there are other potential applications of this work, such as research related to atmospheric lifetimes and fates of organic compounds, or modelling gas-phase reactions of organics in various environments. This database is freely accessible at https://doi.org/10.25326/36 (McGillen et al., 2019).

scholarly journals Evolution of OH reactivity in low-NO volatile organic compound photooxidation investigated by the fully explicit GECKO-A model

2021 ◽  
Author(s):  
Zhe Peng ◽  
Julia Lee-Taylor ◽  
Harald Stark ◽  
John J. Orlando ◽  
Bernard Aumont ◽  
...  
Keyword(s):  
Flow Reactor ◽  
Oxidative Capacity ◽  
Rate Coefficients ◽  
Atmospheric Conditions ◽  
Alkene Oxidation ◽  
Volatile Organic ◽  
Wall Losses ◽  
Uv Lamp ◽  
Kinetics Of ◽  
Significant Underestimation

Abstract. OH reactivity (OHR) is an important control on the oxidative capacity in the atmosphere but remains poorly constrained. For an improved understanding of OHR, its evolution during oxidation of volatile organic compounds (VOCs) is a major aspect requiring better quantification. We use the fully explicit Generator of Explicit Chemistry and Kinetics of Organics in the Atmosphere (GECKO-A) model to study the OHR evolution in the low-NO photooxidation of several VOCs, including decane (an alkane), m-xylene (an aromatic), and isoprene (an alkene). Oxidation progressively produces more saturated and functionalized species. Total organic OHR (including precursor and products, OHRVOC) first increases for decane (as functionalization increases OH rate coefficients), and m-xylene (as much more reactive oxygenated alkenes are formed). For isoprene, C=C bond consumption leads to a rapid drop in OHRVOC before significant production of the first main saturated multifunctional product, i.e., isoprene epoxydiol. The saturated multifunctional species in the oxidation of different precursors have similar average OHRVOC per C atom. The latter oxidation follows a similar course for different precursors, involving fragmentation of multifunctional species to eventual oxidation of C1 and C2 fragments to CO2, leading to a similar evolution of OHRVOC per C atom. An upper limit of the total OH consumption during complete oxidation to CO2 is roughly 3 per C atom. We also explore the trends in radical recycling ratios. We show that differences in the evolution of OHRVOC between the atmosphere and an environmental chamber, and between the atmosphere and an oxidation flow reactor (OFR) can be substantial, with the former being even larger, but these differences are often smaller than between precursors. The Teflon wall losses of oxygenated VOCs in chambers result in substantial deviations of OHRVOC from atmospheric conditions, especially for the oxidation of larger precursors, where multifunctional species may suffer near-complete wall losses, resulting in significant underestimation of OHRVOC. For OFR, the deviations of OHRVOC evolution from the atmospheric case are mainly due to significant OHR contribution from RO2 and lack of efficient organic photolysis. The former can be avoided by lowering the UV lamp setting in OFR, while the latter is shown to be very difficult to avoid. However, the former may significantly offset the slowdown in fragmentation of multifunctional species due to lack of efficient organic photolysis.

scholarly journals Evolution of OH reactivity in NO-free volatile organic compound photooxidation investigated by the fully explicit GECKO-A model

2021 ◽  
Vol 21 (19) ◽  
pp. 14649-14669
Author(s):  
Zhe Peng ◽  
Julia Lee-Taylor ◽  
Harald Stark ◽  
John J. Orlando ◽  
Bernard Aumont ◽  
...  
Keyword(s):  
Flow Reactor ◽  
Oxidative Capacity ◽  
Rate Coefficients ◽  
Atmospheric Conditions ◽  
Alkene Oxidation ◽  
Rural And Urban ◽  
Volatile Organic ◽  
Wall Losses ◽  
Uv Lamp ◽  
Kinetics Of

Abstract. OH reactivity (OHR) is an important control on the oxidative capacity in the atmosphere but remains poorly constrained in many environments, such as remote, rural, and urban atmospheres, as well as laboratory experiment setups under low-NO conditions. For an improved understanding of OHR, its evolution during oxidation of volatile organic compounds (VOCs) is a major aspect requiring better quantification. We use the fully explicit Generator of Explicit Chemistry and Kinetics of Organics in the Atmosphere (GECKO-A) model to study the OHR evolution in the NO-free photooxidation of several VOCs, including decane (an alkane), m-xylene (an aromatic), and isoprene (an alkene). Oxidation progressively produces more saturated and functionalized species. Total organic OHR (including precursor and products, OHRVOC) first increases for decane (as functionalization increases OH rate coefficients) and m-xylene (as much more reactive oxygenated alkenes are formed). For isoprene, C=C bond consumption leads to a rapid drop in OHRVOC before significant production of the first main saturated multifunctional product, i.e., isoprene epoxydiol. The saturated multifunctional species in the oxidation of different precursors have similar average OHRVOC per C atom. The latter oxidation follows a similar course for different precursors, involving fragmentation of multifunctional species to eventual oxidation of C1 and C2 fragments to CO2, leading to a similar evolution of OHRVOC per C atom. An upper limit of the total OH consumption during complete oxidation to CO2 is roughly three per C atom. We also explore the trends in radical recycling ratios. We show that differences in the evolution of OHRVOC between the atmosphere and an environmental chamber, and between the atmosphere and an oxidation flow reactor (OFR), can be substantial, with the former being even larger, but these differences are often smaller than between precursors. The Teflon wall losses of oxygenated VOCs in chambers result in large deviations of OHRVOC from atmospheric conditions, especially for the oxidation of larger precursors, where multifunctional species may suffer substantial wall losses, resulting in significant underestimation of OHRVOC. For OFR, the deviations of OHRVOC evolution from the atmospheric case are mainly due to significant OHR contribution from RO2 and lack of efficient organic photolysis. The former can be avoided by lowering the UV lamp setting in OFR, while the latter is shown to be very difficult to avoid. However, the former may significantly offset the slowdown in fragmentation of multifunctional species due to lack of efficient organic photolysis.

scholarly journals Kinetics of the OH + NO<sub>2</sub> reaction: Rate coefficients (217–333 K, 16–1200 mbar) and fall-off parameters for N<sub>2</sub> and O<sub>2</sub> bath-gases

2019 ◽  
Author(s):  
Damien Amedro ◽  
Arne J. C. Bunkan ◽  
Matias Berasategui ◽  
John N. Crowley
Keyword(s):  
Pressure Range ◽  
Great Influence ◽  
Rate Coefficients ◽  
Atmospheric Conditions ◽  
Collision Efficiency ◽  
Temperature And Pressure ◽  
Photolysis Laser ◽  
Kinetics Of ◽  
Lower Collision

Abstract. The radical terminating, termolecular reaction between OH and NO2 exerts great influence on the NOy / NOx ratio and O3 formation in the atmosphere. Evaluation panels (IUPAC and NASA) recommend rate coefficients for this reaction that disagree by as much as a factor 1.6 at low temperature and pressure. In this work, the title reaction was studied by pulsed laser photolysis-laser induced fluorescence over the pressure range 16–1200 mbar and temperature 217–333 K in N2 bath-gas, with experiments at 295 K (67–333 mbar) for O2. In-situ measurement of NO2 using two optical-absorption set-ups enabled generation of highly precise, accurate rate coefficients in the fall-off pressure range, appropriate for atmospheric conditions. We found, in agreement with previous work, that O2 bath-gas has a lower collision efficiency than N2 with a relative collision efficiency to N2 of 0.74. Using the widely used Troe-type formulation for termolecular reactions we present a new set of parameters with k0(N2) = 2.6 × 10−30 cm6 molecule−2 s−1, k0(O2) = 2.0 × 10−30 cm6 molecule−2 s−1, m = 3.6, k∞ = 6.3 × 10−11 cm3 molecule−1 s−1, Fc = 0.39 and compare our results to previous studies in N2 and O2 bath-gases.

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