AMBIO: A Journal of the Human Environment, Nov 21, 2020
We here reflect on two important articles on stratospheric ozone depletion written by P. J. Crutz... more We here reflect on two important articles on stratospheric ozone depletion written by P. J. Crutzen (1974) and P. J. Crutzen and D. H. Ehhalt (1977) in the early 1970s. These articles provide a clear description of the stratosphere and the most important chemical reactions involved in stratospheric ozone depletion. They present modeling results and provide recommendations for future research on stratospheric ozone depletion caused by chloro-fluoro-carbons, supersonic transport, nitrous oxide, and nuclear explosions. These two articles represent the beginning of a scientific era, which led to discovery of the Antarctic ozone hole and political action in the form of the Montreal Protocol and its amendments.
Correction for ‘Atmospheric chemistry of (Z)- and (E)-1,2-dichloroethene: kinetics and mechanisms... more Correction for ‘Atmospheric chemistry of (Z)- and (E)-1,2-dichloroethene: kinetics and mechanisms of the reactions with Cl atoms, OH radicals, and O3’ by Mads P. Sulbaek Andersen et al., Phys. Chem. Chem. Phys., 2022, 24, 7356–7373, https://doi.org/10.1039/D1CP04877E.
The journal of physical chemistry. A, Jan 22, 2016
FTIR smog chamber techniques were used to study the kinetics of the gas-phase reactions of Cl ato... more FTIR smog chamber techniques were used to study the kinetics of the gas-phase reactions of Cl atoms, OD radicals, and O3 with the five-membered ring-structured compounds tetrahydrofuran (C4H8O, THF), 2-methyltetrahydrofuran (CH3C4H7O, 2-MTHF), 2,5-dimethyltetrahydrofuran ((CH3)2C4H5O, 2,5-DMTHF), and furan (C4H4O). The rate coefficients determined using relative rate methods were kTHF+Cl = (1.96 ± 0.24) × 10(-10), kTHF+OD = (1.81 ± 0.27) × 10(-11), kTHF+O3 = (6.41 ± 2.90) × 10(-21), k2-MTHF+Cl = (2.65 ± 0.43) × 10(-10), k2-MTHF+OD = (2.41 ± 0.51) × 10(-11), k2-MTHF+O3 = (1.87 ± 0.82) × 10(-20), k2,5-DMTHF+OD = (4.56 ± 0.68) × 10(-11), k2,5-DMTHF+Cl = (2.84 ± 0.34) × 10(-10), k2,5-DMTHF+O3 = (4.58 ± 2.18), kfuran+Cl = (2.39 ± 0.27) × 10(-10), and kfuran+O3 = (2.60 ± 0.31) × 10(-18) molecules cm(-3) s(-1). Rate coefficients of the reactions with ozone were also determined using the absolute rate method under pseudo-first-order conditions. OD radicals, in place of OH radicals, were pro...
Smog chamber/Fourier transform infrared (FTIR) techniques were used to measure k(Cl+C(x)F(2x+1)CH... more Smog chamber/Fourier transform infrared (FTIR) techniques were used to measure k(Cl+C(x)F(2x+1)CH(OH)(2)) (x = 1, 3, 4) = (5.84 +/- 0.92) x 10(-13) and k(OH+C(x)F(2x+1)CH(OH)(2)) = (1.22 +/- 0.26) x 10(-13) cm(3) molecule(-1) s(-1) in 700 Torr of N(2) or air at 296 +/- 2 K. The Cl initiated oxidation of CF(3)CH(OH)(2) in 700 Torr of air gave CF(3)COOH in a molar yield of 101 +/- 6%. IR spectra of C(x)F(2x+1)CH(OH)(2) (x = 1, 3, 4) were recorded and are presented. An upper limit of k(CF(3)CHO+H(2)O) < 2 x 10(-23) cm(3) molecule(-1) s(-1) was established for the gas-phase hydration of CF(3)CHO. Bubbling CF(3)CHO/air mixtures through liquid water led to >80% conversion of CF(3)CHO into the hydrate within the approximately 2 s taken for passage through the bubbler. These results suggest that OH radical initiated oxidation of C(x)F(2x+1)CH(OH)(2) hydrates could be a significant source of perfluorinated carboxylic acids in the environment.
An overview of the gas-phase reactions responsible for the photooxidation of air pollutants is pr... more An overview of the gas-phase reactions responsible for the photooxidation of air pollutants is provided. Starting with an introduction to the field of atmospheric chemistry we proceed to discuss the concept, and utility, of atmospheric lifetime. The processes responsible for the degradation of alkanes, alkenes, aromatics, NO x , SO x , CFCs and their replacements are discussed in turn. Areas of uncertainty are highlighted. Finally, the research needs are discussed.
... Physics Letters 240 (1995) 5356 CHEMICAL PHYSICS LETTERS UV absorption spectrum of CH 3OCH2 r... more ... Physics Letters 240 (1995) 5356 CHEMICAL PHYSICS LETTERS UV absorption spectrum of CH 3OCH2 radicals and kinetics of the reaction of CH3OCH202 radicals with NO and NO2 in the gas phase Sarka Langer a, Evert Ljungstr Sm a,*, Thomas Ellermann b, Ole J. Nielsen ...
UV spectra and kinetics for the reactions of alkyl and alkylperoxy radicals from methyl tert-buty... more UV spectra and kinetics for the reactions of alkyl and alkylperoxy radicals from methyl tert-butyl ether (MTBE) were studied in 1 atm of SF6 by the pulse radiolysis-UV absorption technique. UV spectra for the radical mixtures were quantified from 215 to 340 nm. At 240 nm. σR = (2.6 ± 0.4) × 10−18 cm2 molecule−1 and σRO2 = (4.1 ±
AMBIO: A Journal of the Human Environment, Nov 21, 2020
We here reflect on two important articles on stratospheric ozone depletion written by P. J. Crutz... more We here reflect on two important articles on stratospheric ozone depletion written by P. J. Crutzen (1974) and P. J. Crutzen and D. H. Ehhalt (1977) in the early 1970s. These articles provide a clear description of the stratosphere and the most important chemical reactions involved in stratospheric ozone depletion. They present modeling results and provide recommendations for future research on stratospheric ozone depletion caused by chloro-fluoro-carbons, supersonic transport, nitrous oxide, and nuclear explosions. These two articles represent the beginning of a scientific era, which led to discovery of the Antarctic ozone hole and political action in the form of the Montreal Protocol and its amendments.
Correction for ‘Atmospheric chemistry of (Z)- and (E)-1,2-dichloroethene: kinetics and mechanisms... more Correction for ‘Atmospheric chemistry of (Z)- and (E)-1,2-dichloroethene: kinetics and mechanisms of the reactions with Cl atoms, OH radicals, and O3’ by Mads P. Sulbaek Andersen et al., Phys. Chem. Chem. Phys., 2022, 24, 7356–7373, https://doi.org/10.1039/D1CP04877E.
The journal of physical chemistry. A, Jan 22, 2016
FTIR smog chamber techniques were used to study the kinetics of the gas-phase reactions of Cl ato... more FTIR smog chamber techniques were used to study the kinetics of the gas-phase reactions of Cl atoms, OD radicals, and O3 with the five-membered ring-structured compounds tetrahydrofuran (C4H8O, THF), 2-methyltetrahydrofuran (CH3C4H7O, 2-MTHF), 2,5-dimethyltetrahydrofuran ((CH3)2C4H5O, 2,5-DMTHF), and furan (C4H4O). The rate coefficients determined using relative rate methods were kTHF+Cl = (1.96 ± 0.24) × 10(-10), kTHF+OD = (1.81 ± 0.27) × 10(-11), kTHF+O3 = (6.41 ± 2.90) × 10(-21), k2-MTHF+Cl = (2.65 ± 0.43) × 10(-10), k2-MTHF+OD = (2.41 ± 0.51) × 10(-11), k2-MTHF+O3 = (1.87 ± 0.82) × 10(-20), k2,5-DMTHF+OD = (4.56 ± 0.68) × 10(-11), k2,5-DMTHF+Cl = (2.84 ± 0.34) × 10(-10), k2,5-DMTHF+O3 = (4.58 ± 2.18), kfuran+Cl = (2.39 ± 0.27) × 10(-10), and kfuran+O3 = (2.60 ± 0.31) × 10(-18) molecules cm(-3) s(-1). Rate coefficients of the reactions with ozone were also determined using the absolute rate method under pseudo-first-order conditions. OD radicals, in place of OH radicals, were pro...
Smog chamber/Fourier transform infrared (FTIR) techniques were used to measure k(Cl+C(x)F(2x+1)CH... more Smog chamber/Fourier transform infrared (FTIR) techniques were used to measure k(Cl+C(x)F(2x+1)CH(OH)(2)) (x = 1, 3, 4) = (5.84 +/- 0.92) x 10(-13) and k(OH+C(x)F(2x+1)CH(OH)(2)) = (1.22 +/- 0.26) x 10(-13) cm(3) molecule(-1) s(-1) in 700 Torr of N(2) or air at 296 +/- 2 K. The Cl initiated oxidation of CF(3)CH(OH)(2) in 700 Torr of air gave CF(3)COOH in a molar yield of 101 +/- 6%. IR spectra of C(x)F(2x+1)CH(OH)(2) (x = 1, 3, 4) were recorded and are presented. An upper limit of k(CF(3)CHO+H(2)O) < 2 x 10(-23) cm(3) molecule(-1) s(-1) was established for the gas-phase hydration of CF(3)CHO. Bubbling CF(3)CHO/air mixtures through liquid water led to >80% conversion of CF(3)CHO into the hydrate within the approximately 2 s taken for passage through the bubbler. These results suggest that OH radical initiated oxidation of C(x)F(2x+1)CH(OH)(2) hydrates could be a significant source of perfluorinated carboxylic acids in the environment.
An overview of the gas-phase reactions responsible for the photooxidation of air pollutants is pr... more An overview of the gas-phase reactions responsible for the photooxidation of air pollutants is provided. Starting with an introduction to the field of atmospheric chemistry we proceed to discuss the concept, and utility, of atmospheric lifetime. The processes responsible for the degradation of alkanes, alkenes, aromatics, NO x , SO x , CFCs and their replacements are discussed in turn. Areas of uncertainty are highlighted. Finally, the research needs are discussed.
... Physics Letters 240 (1995) 5356 CHEMICAL PHYSICS LETTERS UV absorption spectrum of CH 3OCH2 r... more ... Physics Letters 240 (1995) 5356 CHEMICAL PHYSICS LETTERS UV absorption spectrum of CH 3OCH2 radicals and kinetics of the reaction of CH3OCH202 radicals with NO and NO2 in the gas phase Sarka Langer a, Evert Ljungstr Sm a,*, Thomas Ellermann b, Ole J. Nielsen ...
UV spectra and kinetics for the reactions of alkyl and alkylperoxy radicals from methyl tert-buty... more UV spectra and kinetics for the reactions of alkyl and alkylperoxy radicals from methyl tert-butyl ether (MTBE) were studied in 1 atm of SF6 by the pulse radiolysis-UV absorption technique. UV spectra for the radical mixtures were quantified from 215 to 340 nm. At 240 nm. σR = (2.6 ± 0.4) × 10−18 cm2 molecule−1 and σRO2 = (4.1 ±
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