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Luc Vereecken - One of the best experts on this subject based on the ideXlab platform.
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kinetics of dimethyl sulfide dms reactions with isoprene derived criegee intermediates studied with direct uv absorption
Atmospheric Chemistry and Physics, 2020Co-Authors: Isabelle Weber, Christa Fittschen, Luc VereeckenAbstract:Abstract. Criegee intermediates (CIs) are formed in the Ozonolysis of unsaturated hydrocarbons and play a role in atmospheric chemistry as a non-photolytic OH source or a strong oxidant. Using a relative rate method in an Ozonolysis experiment, Newland et al. [Atmos. Chem. Phys., 15, 9521–9536, 2015] reported high reactivity of isoprene-derived Criegee intermediates towards dimethyl sulfide (DMS) relative to that towards SO2 with the ratio of the rate coefficients kDMS+CI / kSO2+CI = 3.5 ± 1.8. Here we reinvestigated the kinetics of DMS reactions with two major Criegee intermediates formed in isoprene Ozonolysis, CH2OO and methyl vinyl ketone oxide (MVKO). The individual CI was prepared following reported photolytic method with suitable (diiodo) precursors in the presence of O2. The concentration of CH2OO or MVKO was monitored directly in real time through their intense UV-visible absorption. Our results indicate the reactions of DMS with CH2OO and MVKO are both very slow; the upper limits of the rate coefficients are 4 orders of magnitude smaller than that reported by Newland et al. These results suggest that the Ozonolysis experiment could be complicated such that interpretation should be careful and these CIs would not oxidize atmospheric DMS at any substantial level.
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the gas phase Ozonolysis of β caryophyllene c15h24 part i an experimental study
Physical Chemistry Chemical Physics, 2009Co-Authors: Richard Winterhalter, Luc Vereecken, Jozef Peeters, Frank Herrmann, Basem Kanawati, Thanh Lam Nguyen, G K MoortgatAbstract:The gas phase reaction of ozone with β-caryophyllene was investigated in a static glass reactor at 750 Torr and 296 K under various experimental conditions. The reactants and gas phase products were monitored by FTIR-spectroscopy and proton-transfer-reaction mass spectrometry (PTR-MS). Aerosol formation was monitored with a scanning mobility particle sizer (SMPS) and particulate products analysed by liquid chromatography/mass spectrometry (HPLC-MS). The different reactivity of the two double bonds in β-caryophyllene was probed by experiments with different ratios of reactants. An average rate coefficient at 295 K for the first-generation products was determined as 1.1 × 10−16 cm3 molecule−1 s−1. Using cyclohexane as scavenger, an OH-radical yield of (10.4 ± 2.3)% was determined for the Ozonolysis of the more reactive internal double bond, whereas the average OH-radical yield for the Ozonolysis of the first-generation products was found to be (16.4 ± 3.6)%. Measured gas phase products are CO, CO2 and HCHO with average yields of (2.0 ± 1.8)%, (3.8 ± 2.8)% and (7.7 ± 4.0)%, respectively for the more reactive internal double bond and (5.5 ± 4.8)%, (8.2 ± 2.8)% and (60 ± 6)%, respectively from Ozonolysis of the less reactive double bond of the first-generation products. The residual FTIR spectra indicate the formation of an internal secondary ozonide of β-caryophyllene. From experiments using HCOOH as a Criegee intermediate (CI) scavenger, it was concluded that at least 60% of the formed CI are collisionally stabilized. The aerosol yield in the Ozonolysis of β-caryophyllene was estimated from the measured particle size distributions. In the absence of a CI scavenger the yield ranged between 5 and 24%, depending on the aerosol mass. The yield increases with addition of water vapour or with higher concentrations of formic acid. In the presence of HCHO, lower aerosol yields were observed. This suggests that HCOOH adds to a Criegee intermediate to form a low-volatility compound responsible for aerosol formation. The underlying reaction mechanisms are discussed and compared with the results from the accompanying theoretical paper.
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modeling aerosol formation in alpha pinene photo oxidation experiments
Journal of Geophysical Research, 2008Co-Authors: M Capouet, Luc Vereecken, J F Muller, K Ceulemans, Steven Compernolle, Jozef PeetersAbstract:[1] We present BOREAM (Biogenic hydrocarbon Oxidation and Related Aerosol formation Model), a detailed model for the oxidation of α-pinene and the resulting formation of secondary organic aerosol (SOA). It is based on a quasi-explicit gas phase mechanism for the formation of primary products, developed on objective grounds using advanced theoretical methods, and on a simplified representation for the further oxidation of the products. The partitioning of the products follows a kinetic representation with coefficients estimated from vapor pressures calculated using a dedicated group contribution method. Particle phase and heterogeneous reactions are generally neglected, but the impact of peroxyhemiacetal formation in the aerosol is tested on the basis of laboratory estimates of the reaction rates. The model is evaluated against 28 laboratory experiments from 6 studies of α-pinene photo-oxidation covering a wide range of photochemical conditions. In contrast with previous modeling studies, the modeled and measured SOA yields agree to within a factor of 2 in most cases. The SOA yields are underestimated for the Ozonolysis experiments of Presto et al. (2005a) when the standard version of the Ozonolysis mechanism is used, presumably because of the lack of credible pathways for the formation of pinic and hydroxy pinonic acid. The underestimation is drastically reduced when the mechanism is modified to account for the formation of these compounds. Accounting for peroxyhemiacetal formation in the particle phase is found to further increase the SOA yields by about one third in high VOC Ozonolysis experiments and to have a much smaller impact in all other cases. The model calculates that Ozonolysis contributes about twice more to SOA formation than oxidation by OH, whereas NO3-initiated oxidation is negligible. In agreement with previous studies, low NOx conditions and low temperatures are calculated to favor aerosol formation, but the estimated temperature dependence is stronger than found in recent laboratory experiments.
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modeling aerosol formation in alpha pinene photo oxidation experiments
Journal of Geophysical Research, 2008Co-Authors: M Capouet, Luc Vereecken, K Ceulemans, Steven Compernolle, Jeanfrancois Muller, Jozef PeetersAbstract:[1] We present BOREAM (Biogenic hydrocarbon Oxidation and Related Aerosol formation Model), a detailed model for the oxidation of α-pinene and the resulting formation of secondary organic aerosol (SOA). It is based on a quasi-explicit gas phase mechanism for the formation of primary products, developed on objective grounds using advanced theoretical methods, and on a simplified representation for the further oxidation of the products. The partitioning of the products follows a kinetic representation with coefficients estimated from vapor pressures calculated using a dedicated group contribution method. Particle phase and heterogeneous reactions are generally neglected, but the impact of peroxyhemiacetal formation in the aerosol is tested on the basis of laboratory estimates of the reaction rates. The model is evaluated against 28 laboratory experiments from 6 studies of α-pinene photo-oxidation covering a wide range of photochemical conditions. In contrast with previous modeling studies, the modeled and measured SOA yields agree to within a factor of 2 in most cases. The SOA yields are underestimated for the Ozonolysis experiments of Presto et al. (2005a) when the standard version of the Ozonolysis mechanism is used, presumably because of the lack of credible pathways for the formation of pinic and hydroxy pinonic acid. The underestimation is drastically reduced when the mechanism is modified to account for the formation of these compounds. Accounting for peroxyhemiacetal formation in the particle phase is found to further increase the SOA yields by about one third in high VOC Ozonolysis experiments and to have a much smaller impact in all other cases. The model calculates that Ozonolysis contributes about twice more to SOA formation than oxidation by OH, whereas NO3-initiated oxidation is negligible. In agreement with previous studies, low NOx conditions and low temperatures are calculated to favor aerosol formation, but the estimated temperature dependence is stronger than found in recent laboratory experiments.
Jozef Peeters - One of the best experts on this subject based on the ideXlab platform.
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the gas phase Ozonolysis of β caryophyllene c15h24 part i an experimental study
Physical Chemistry Chemical Physics, 2009Co-Authors: Richard Winterhalter, Luc Vereecken, Jozef Peeters, Frank Herrmann, Basem Kanawati, Thanh Lam Nguyen, G K MoortgatAbstract:The gas phase reaction of ozone with β-caryophyllene was investigated in a static glass reactor at 750 Torr and 296 K under various experimental conditions. The reactants and gas phase products were monitored by FTIR-spectroscopy and proton-transfer-reaction mass spectrometry (PTR-MS). Aerosol formation was monitored with a scanning mobility particle sizer (SMPS) and particulate products analysed by liquid chromatography/mass spectrometry (HPLC-MS). The different reactivity of the two double bonds in β-caryophyllene was probed by experiments with different ratios of reactants. An average rate coefficient at 295 K for the first-generation products was determined as 1.1 × 10−16 cm3 molecule−1 s−1. Using cyclohexane as scavenger, an OH-radical yield of (10.4 ± 2.3)% was determined for the Ozonolysis of the more reactive internal double bond, whereas the average OH-radical yield for the Ozonolysis of the first-generation products was found to be (16.4 ± 3.6)%. Measured gas phase products are CO, CO2 and HCHO with average yields of (2.0 ± 1.8)%, (3.8 ± 2.8)% and (7.7 ± 4.0)%, respectively for the more reactive internal double bond and (5.5 ± 4.8)%, (8.2 ± 2.8)% and (60 ± 6)%, respectively from Ozonolysis of the less reactive double bond of the first-generation products. The residual FTIR spectra indicate the formation of an internal secondary ozonide of β-caryophyllene. From experiments using HCOOH as a Criegee intermediate (CI) scavenger, it was concluded that at least 60% of the formed CI are collisionally stabilized. The aerosol yield in the Ozonolysis of β-caryophyllene was estimated from the measured particle size distributions. In the absence of a CI scavenger the yield ranged between 5 and 24%, depending on the aerosol mass. The yield increases with addition of water vapour or with higher concentrations of formic acid. In the presence of HCHO, lower aerosol yields were observed. This suggests that HCOOH adds to a Criegee intermediate to form a low-volatility compound responsible for aerosol formation. The underlying reaction mechanisms are discussed and compared with the results from the accompanying theoretical paper.
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modeling aerosol formation in alpha pinene photo oxidation experiments
Journal of Geophysical Research, 2008Co-Authors: M Capouet, Luc Vereecken, J F Muller, K Ceulemans, Steven Compernolle, Jozef PeetersAbstract:[1] We present BOREAM (Biogenic hydrocarbon Oxidation and Related Aerosol formation Model), a detailed model for the oxidation of α-pinene and the resulting formation of secondary organic aerosol (SOA). It is based on a quasi-explicit gas phase mechanism for the formation of primary products, developed on objective grounds using advanced theoretical methods, and on a simplified representation for the further oxidation of the products. The partitioning of the products follows a kinetic representation with coefficients estimated from vapor pressures calculated using a dedicated group contribution method. Particle phase and heterogeneous reactions are generally neglected, but the impact of peroxyhemiacetal formation in the aerosol is tested on the basis of laboratory estimates of the reaction rates. The model is evaluated against 28 laboratory experiments from 6 studies of α-pinene photo-oxidation covering a wide range of photochemical conditions. In contrast with previous modeling studies, the modeled and measured SOA yields agree to within a factor of 2 in most cases. The SOA yields are underestimated for the Ozonolysis experiments of Presto et al. (2005a) when the standard version of the Ozonolysis mechanism is used, presumably because of the lack of credible pathways for the formation of pinic and hydroxy pinonic acid. The underestimation is drastically reduced when the mechanism is modified to account for the formation of these compounds. Accounting for peroxyhemiacetal formation in the particle phase is found to further increase the SOA yields by about one third in high VOC Ozonolysis experiments and to have a much smaller impact in all other cases. The model calculates that Ozonolysis contributes about twice more to SOA formation than oxidation by OH, whereas NO3-initiated oxidation is negligible. In agreement with previous studies, low NOx conditions and low temperatures are calculated to favor aerosol formation, but the estimated temperature dependence is stronger than found in recent laboratory experiments.
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modeling aerosol formation in alpha pinene photo oxidation experiments
Journal of Geophysical Research, 2008Co-Authors: M Capouet, Luc Vereecken, K Ceulemans, Steven Compernolle, Jeanfrancois Muller, Jozef PeetersAbstract:[1] We present BOREAM (Biogenic hydrocarbon Oxidation and Related Aerosol formation Model), a detailed model for the oxidation of α-pinene and the resulting formation of secondary organic aerosol (SOA). It is based on a quasi-explicit gas phase mechanism for the formation of primary products, developed on objective grounds using advanced theoretical methods, and on a simplified representation for the further oxidation of the products. The partitioning of the products follows a kinetic representation with coefficients estimated from vapor pressures calculated using a dedicated group contribution method. Particle phase and heterogeneous reactions are generally neglected, but the impact of peroxyhemiacetal formation in the aerosol is tested on the basis of laboratory estimates of the reaction rates. The model is evaluated against 28 laboratory experiments from 6 studies of α-pinene photo-oxidation covering a wide range of photochemical conditions. In contrast with previous modeling studies, the modeled and measured SOA yields agree to within a factor of 2 in most cases. The SOA yields are underestimated for the Ozonolysis experiments of Presto et al. (2005a) when the standard version of the Ozonolysis mechanism is used, presumably because of the lack of credible pathways for the formation of pinic and hydroxy pinonic acid. The underestimation is drastically reduced when the mechanism is modified to account for the formation of these compounds. Accounting for peroxyhemiacetal formation in the particle phase is found to further increase the SOA yields by about one third in high VOC Ozonolysis experiments and to have a much smaller impact in all other cases. The model calculates that Ozonolysis contributes about twice more to SOA formation than oxidation by OH, whereas NO3-initiated oxidation is negligible. In agreement with previous studies, low NOx conditions and low temperatures are calculated to favor aerosol formation, but the estimated temperature dependence is stronger than found in recent laboratory experiments.
M Capouet - One of the best experts on this subject based on the ideXlab platform.
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modeling aerosol formation in alpha pinene photo oxidation experiments
Journal of Geophysical Research, 2008Co-Authors: M Capouet, Luc Vereecken, J F Muller, K Ceulemans, Steven Compernolle, Jozef PeetersAbstract:[1] We present BOREAM (Biogenic hydrocarbon Oxidation and Related Aerosol formation Model), a detailed model for the oxidation of α-pinene and the resulting formation of secondary organic aerosol (SOA). It is based on a quasi-explicit gas phase mechanism for the formation of primary products, developed on objective grounds using advanced theoretical methods, and on a simplified representation for the further oxidation of the products. The partitioning of the products follows a kinetic representation with coefficients estimated from vapor pressures calculated using a dedicated group contribution method. Particle phase and heterogeneous reactions are generally neglected, but the impact of peroxyhemiacetal formation in the aerosol is tested on the basis of laboratory estimates of the reaction rates. The model is evaluated against 28 laboratory experiments from 6 studies of α-pinene photo-oxidation covering a wide range of photochemical conditions. In contrast with previous modeling studies, the modeled and measured SOA yields agree to within a factor of 2 in most cases. The SOA yields are underestimated for the Ozonolysis experiments of Presto et al. (2005a) when the standard version of the Ozonolysis mechanism is used, presumably because of the lack of credible pathways for the formation of pinic and hydroxy pinonic acid. The underestimation is drastically reduced when the mechanism is modified to account for the formation of these compounds. Accounting for peroxyhemiacetal formation in the particle phase is found to further increase the SOA yields by about one third in high VOC Ozonolysis experiments and to have a much smaller impact in all other cases. The model calculates that Ozonolysis contributes about twice more to SOA formation than oxidation by OH, whereas NO3-initiated oxidation is negligible. In agreement with previous studies, low NOx conditions and low temperatures are calculated to favor aerosol formation, but the estimated temperature dependence is stronger than found in recent laboratory experiments.
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modeling aerosol formation in alpha pinene photo oxidation experiments
Journal of Geophysical Research, 2008Co-Authors: M Capouet, Luc Vereecken, K Ceulemans, Steven Compernolle, Jeanfrancois Muller, Jozef PeetersAbstract:[1] We present BOREAM (Biogenic hydrocarbon Oxidation and Related Aerosol formation Model), a detailed model for the oxidation of α-pinene and the resulting formation of secondary organic aerosol (SOA). It is based on a quasi-explicit gas phase mechanism for the formation of primary products, developed on objective grounds using advanced theoretical methods, and on a simplified representation for the further oxidation of the products. The partitioning of the products follows a kinetic representation with coefficients estimated from vapor pressures calculated using a dedicated group contribution method. Particle phase and heterogeneous reactions are generally neglected, but the impact of peroxyhemiacetal formation in the aerosol is tested on the basis of laboratory estimates of the reaction rates. The model is evaluated against 28 laboratory experiments from 6 studies of α-pinene photo-oxidation covering a wide range of photochemical conditions. In contrast with previous modeling studies, the modeled and measured SOA yields agree to within a factor of 2 in most cases. The SOA yields are underestimated for the Ozonolysis experiments of Presto et al. (2005a) when the standard version of the Ozonolysis mechanism is used, presumably because of the lack of credible pathways for the formation of pinic and hydroxy pinonic acid. The underestimation is drastically reduced when the mechanism is modified to account for the formation of these compounds. Accounting for peroxyhemiacetal formation in the particle phase is found to further increase the SOA yields by about one third in high VOC Ozonolysis experiments and to have a much smaller impact in all other cases. The model calculates that Ozonolysis contributes about twice more to SOA formation than oxidation by OH, whereas NO3-initiated oxidation is negligible. In agreement with previous studies, low NOx conditions and low temperatures are calculated to favor aerosol formation, but the estimated temperature dependence is stronger than found in recent laboratory experiments.
G K Moortgat - One of the best experts on this subject based on the ideXlab platform.
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the gas phase Ozonolysis of β caryophyllene c15h24 part i an experimental study
Physical Chemistry Chemical Physics, 2009Co-Authors: Richard Winterhalter, Luc Vereecken, Jozef Peeters, Frank Herrmann, Basem Kanawati, Thanh Lam Nguyen, G K MoortgatAbstract:The gas phase reaction of ozone with β-caryophyllene was investigated in a static glass reactor at 750 Torr and 296 K under various experimental conditions. The reactants and gas phase products were monitored by FTIR-spectroscopy and proton-transfer-reaction mass spectrometry (PTR-MS). Aerosol formation was monitored with a scanning mobility particle sizer (SMPS) and particulate products analysed by liquid chromatography/mass spectrometry (HPLC-MS). The different reactivity of the two double bonds in β-caryophyllene was probed by experiments with different ratios of reactants. An average rate coefficient at 295 K for the first-generation products was determined as 1.1 × 10−16 cm3 molecule−1 s−1. Using cyclohexane as scavenger, an OH-radical yield of (10.4 ± 2.3)% was determined for the Ozonolysis of the more reactive internal double bond, whereas the average OH-radical yield for the Ozonolysis of the first-generation products was found to be (16.4 ± 3.6)%. Measured gas phase products are CO, CO2 and HCHO with average yields of (2.0 ± 1.8)%, (3.8 ± 2.8)% and (7.7 ± 4.0)%, respectively for the more reactive internal double bond and (5.5 ± 4.8)%, (8.2 ± 2.8)% and (60 ± 6)%, respectively from Ozonolysis of the less reactive double bond of the first-generation products. The residual FTIR spectra indicate the formation of an internal secondary ozonide of β-caryophyllene. From experiments using HCOOH as a Criegee intermediate (CI) scavenger, it was concluded that at least 60% of the formed CI are collisionally stabilized. The aerosol yield in the Ozonolysis of β-caryophyllene was estimated from the measured particle size distributions. In the absence of a CI scavenger the yield ranged between 5 and 24%, depending on the aerosol mass. The yield increases with addition of water vapour or with higher concentrations of formic acid. In the presence of HCHO, lower aerosol yields were observed. This suggests that HCOOH adds to a Criegee intermediate to form a low-volatility compound responsible for aerosol formation. The underlying reaction mechanisms are discussed and compared with the results from the accompanying theoretical paper.
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formation of new particles in the gas phase Ozonolysis of monoterpenes
Atmospheric Environment, 2000Co-Authors: S W Koch, Peter Neeb, Richard Winterhalter, E Uherek, Antje Kolloff, G K MoortgatAbstract:Abstract The formation of organic acids and secondary organic aerosol in the gas-phase Ozonolysis was investigated by laboratory experiments at 295±2 K in the absence of seed aerosol for a series of monoterpenes (β-pinene, sabinene, α-pinene, Δ3-carene, limonene, terpinolene) and methylene-cyclo-hexane and methyl-cyclo-hexene as model compounds. In the filter samples of the aerosol produced by Ozonolysis series of organic acids were identified as methyl ester using GC/MS. In the Ozonolysis of β-pinene, sabinene, α-pinene, Δ3-carene and limonene the corresponding C9-dicarboxylic acids were found as main products of the organic acid fraction. In case of terpinolene, methylene-cyclo-hexane and methyl-cyclo-hexene C7- and C6-dicarboxylic acids, respectively, were detected. The yields of these dicarboxylic acids were determined to range between 1 and 5 mol% using ion chromatography. Particle formation was observed with a 10 nm condensation nuclei counter after the consumption of (6.1±0.3)×1010 molecule cm−3 of β-pinene, sabinene, α-pinene, Δ3-carene and limonene, respectively. In case of terpinolene, methylene-cyclo-hexane and methyl-cyclo-hexene (1.8±0.1)×1011 molecule cm−3 of the reactants were converted. Upper limits for the partial vapor pressures of the dicarboxylic acids in the aerosol were determined to be (5.6±4.0)×10−8 Torr for the C9-dicarboxylic acids and (1.7±1.2)×10−7 Torr for the C7- and C6-dicarboxylic acids. The formation of secondary organic aerosol by Ozonolysis of terpenes under suitable atmospheric conditions has most likely to be taken into account.
Masatomo Nojima - One of the best experts on this subject based on the ideXlab platform.
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ozonolyses of 4 4 dimethyl 2 cyclohexen 1 yl acetate and 4 4 dimethyl 2 cyclopenten 1 yl acetate competition between the steric effects of the allylic methyl groups and the electronic effects of the acetoxy group on the direction of cleavage of the primary ozonides
Journal of Organic Chemistry, 1996Co-Authors: Shinichi Kawamura, And Hideyuki Yamakoshi, Masatomo NojimaAbstract:In order to understand the relative directing effects of the substituent steric and electronic effects on the cleavage of the primary ozonides, ozonolyses of a series of cyclohexene and cyclopentene derivatives were conducted in methanol or in ether in the presence of trifluoroacetophenone. The Ozonolysis of 4,4-dimethyl-2-cyclohexen-1-yl acetate (1k) in methanol provided exclusively the α-methoxyalkyl hydroperoxide 7k derived from capture of 5-acetoxy-5-formyl-2,2-dimethylpentanal oxide by the solvent, while in the case of the relevant 4,4-dimethyl-2-cyclopenten-1-yl acetate (1l) the solvent-captured product 6l derived from trapping of 2-acetoxy-5-formyl-5-methylpentanal oxide was the major product. The remarkable difference in the regiochemistry of the fragmentation between the primary ozonides, 2k and 2l, is rationalized in terms of the significant difference in the steric congestion.
