Atmospheric photodissociation lifetimes for nitromethane, methyl nitrite, and methyl nitrate

Taylor, William D.; Allston, Thomas D; Moscato, M. J.; Fazekas, G.B.; Kozłowski, Roman; Takacs, G. A.

doi:10.1002/kin.550120404

Cited by 386 publications

(272 citation statements)

References 67 publications

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“…OH reaction experiments employing the photolysis of methyl nitrite (CH 3 ONO) as an OH source (R1-R2) utilized only a single shielded UV bulb, yielding B30 times lower photon flux. Using published cross sections 23 and an assumed quantum yield of 1 with the measured photon flux gives an estimated j(CH 3 ONO) of 0.9 Â 10 À5 s À1 for these experiments.…”

Section: Methodsmentioning

confidence: 96%

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Photolysis, OH reactivity and ozone reactivity of a proxy for isoprene-derived hydroperoxyenals (HPALDs)

Wolfe

Crounse

Parrish

et al. 2012

Phys. Chem. Chem. Phys.

103

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The C 5 -hydroperoxyenals (C 5 -HPALDs) are a newly-recognized class of multi-functional hydrocarbons produced during the hydroxyl radical (OH)-initiated oxidation of isoprene. Recent theoretical calculations suggest that fast photolysis of these compounds may be an important OH source in high-isoprene, low-NO regions. We report experimental constraints for key parameters of photolysis, OH reaction and ozone reaction of these compounds as derived from a closelyrelated, custom-synthesized C 6 -HPALD. The photolysis quantum yield is 1.0 AE 0.4 over the range 300-400 nm, assuming an absorption cross section equal to the average of those measured for several analogous enals. The yield of OH from photolysis was determined as 1.0 AE 0.8. The OH reaction rate constant is (5.1 AE 1.8) Â 10 À11 cm 3 molecule À1 s À1 at 296 K. The ozone reaction rate constant is (1.2 AE 0.2) Â 10 À18 cm 3 molecule À1 s À1 at 296 K. These results are consistent with previous first-principles estimates, though the nature and fate of secondary oxidation products remains uncertain. Incorporation of C 5 -HPALD chemistry with the above parameters in a 0-D box model, along with experimentally-constrained rates for C 5 -HPALD production from isomerization of first-generation isoprene hydroxyperoxy radicals, is found to enhance modeled OH concentrations by 5-16% relative to the traditional isoprene oxidation mechanism for the chemical regimes of recent observational studies in rural and remote regions. This enhancement in OH will increase if C 5 -HPALD photo-oxidation products also photolyze to yield additional OH or if the C 5 -HPALD production rate is faster than has been observed.

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Section: Methodsmentioning

confidence: 96%

“…23 Purity was checked using FTIR spectroscopy. For use in experiments, CH 3 ONO was removed from liquid nitrogen and slowly warmed, releasing B15 Torr of the vapor into an evacuated 500 cm 3 bulb.…”

Section: Methodsmentioning

confidence: 99%

Photolysis, OH reactivity and ozone reactivity of a proxy for isoprene-derived hydroperoxyenals (HPALDs)

Wolfe

Crounse

Parrish

et al. 2012

Phys. Chem. Chem. Phys.

103

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“…This process produces NO and NO 2 as side products, which are also introduced to the chamber. CH 3 ONO was synthesized, purified, and stored according to the procedure outlined by Taylor et al (1980). CH 3 ONO was warmed from liquid nitrogen temperatures and vaporized into an evacuated 500 ml glass bulb and introduced into the chamber with an air stream of 5 l min −1 .…”

Section: Methodsmentioning

confidence: 99%

α-pinene photooxidation under controlled chemical conditions – Part 2: SOA yield and composition in low- and high-NO<sub>x</sub> environments

et al. 2012

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Abstract. The gas-phase oxidation of α-pinene produces a large amount of secondary organic aerosol (SOA) in the atmosphere. A number of carboxylic acids, organosulfates and nitrooxy organosulfates associated with α-pinene have been found in field samples and some are used as tracers of α-pinene oxidation. α-pinene reacts readily with OH and O 3 in the atmosphere followed by reactions with both HO 2 and NO. Due to the large number of potential reaction pathways, it can be difficult to determine what conditions lead to SOA. To better understand the SOA yield and chemical composition from low-and high-NO x OH oxidation of α-pinene, studies were conducted in the Caltech atmospheric chamber under controlled chemical conditions. Experiments used low O 3 concentrations to ensure that OH was the main oxidant and low α-pinene concentrations such that the peroxy radical (RO 2 ) reacted primarily with either HO 2 under low-NO x conditions or NO under high-NO x conditions. SOA yield was suppressed under conditions of high-NO x . SOA yield under high-NO x conditions was greater when ammonium sulfate/sulfuric acid seed particles (highly acidic) were present prior to the onset of growth than when ammonium sulfate seed particles (mildly acidic) were present; this dependence was not observed under low-NO x conditions. When aerosol seed particles were introduced after OH oxidation, allowing for later generation species to be exposed to fresh inorganic seed particles, a number of low-NO x products partitioned to the highly acidic aerosol. This indicates that the effect of seed acidity and SOA yield might be under-estimated in traditional experiments where aerosol seed particles are introduced prior to oxidation. We also identify the presence of a number of carboxylic acids that are used as tracer compounds of α-pinene oxidation in the field as well as the formation of organosulfates and nitrooxy organosulfates. A number of the carboxylic acids were observed under all conditions, however, pinic and pinonic acid were only observed under low-NO x conditions. Evidence is provided for particle-phase sulfate esterification of multi-functional alcohols.

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“…n-Pentadecane (99%), methyl nitrite (synthesized according to Taylor et al 1980), NO, and (in one experiment) water were added to the chamber from a glass bulb in a flow of N 2 and dioctyl sebacate (DOS, 97%) seed particles were generated using a vaporization-condensation apparatus. NO was added to suppress O 3 and NO 3 radical …”

Section: Experimental Section Environmental Chamber Methodsmentioning

confidence: 99%

Chemical Mechanisms of Aging of Aerosol Formed from the Reaction ofn-Pentadecane with OH Radicals in the Presence of NO_x

Aimanant

Ziemann

2013

Aerosol Science and Technology

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The effects of aging via gas-phase oxidation and heterogeneous/multiphase reactions on the composition and volatility of secondary organic aerosol (SOA) were investigated in a series of environmental chamber experiments. SOA was formed from the reaction of n-pentadecane, a C 15 intermediate volatility alkane, with OH radicals in the presence of NO x under conditions corresponding to ∼1.5 and ∼15 h of daytime oxidation, and analyzed using a suite of real-time and offline methods. Functional group analysis indicated that the average number of nitrate, hydroxyl, carbonyl, carboxyl, ester, acylperoxynitrate, and methylene groups per C 15 molecule were 0.84, 1.07, 0.25, 0.00, 0.00, 0.00, and 12.84 in less aged SOA and 1.25, 0.69, 0.32, 0.00, 0.33, 0.10, and 12.27 in more aged SOA, and the corresponding O/C, H/C, and N/C ratios determined by offline elemental analysis were 0.32, 2.20, and 0.062, and 0.31, 1.86, and 0.061, respectively, similar to each other and in good agreement with values calculated from functional group composition. Time-dependent SOA yields and temperatureprogrammed thermal desorption (TPTD) analysis showed that the more aged SOA was much less volatile and more chemically complex, and when combined with particle mass spectra indicated that the major SOA components included 1,4-hydroxynitrates, cyclic hemiacetals (CHA), cyclic hemiacetal nitrates (CHAN), and related compounds, as well as hemiacetal (HA) and acetal oligomers. The effects of aging on functional group composition were due primarily to dehydration of CHA and formation of second-and thirdgeneration products via gas-phase OH radical reactions, whereas SOA volatility was reduced primarily by enhanced formation of HA and acetal oligomers through heterogeneous/multiphase reactions involving these multigeneration products. These results can be explained using well-established gas-phase and heterogeneous/multiphase reaction mechanisms.

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Atmospheric photodissociation lifetimes for nitromethane, methyl nitrite, and methyl nitrate

Cited by 386 publications

References 67 publications

Photolysis, OH reactivity and ozone reactivity of a proxy for isoprene-derived hydroperoxyenals (HPALDs)

Photolysis, OH reactivity and ozone reactivity of a proxy for isoprene-derived hydroperoxyenals (HPALDs)

α-pinene photooxidation under controlled chemical conditions – Part 2: SOA yield and composition in low- and high-NO<sub>x</sub> environments

Chemical Mechanisms of Aging of Aerosol Formed from the Reaction ofn-Pentadecane with OH Radicals in the Presence of NO_x

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Atmospheric photodissociation lifetimes for nitromethane, methyl nitrite, and methyl nitrate

Cited by 386 publications

References 67 publications

Photolysis, OH reactivity and ozone reactivity of a proxy for isoprene-derived hydroperoxyenals (HPALDs)

Photolysis, OH reactivity and ozone reactivity of a proxy for isoprene-derived hydroperoxyenals (HPALDs)

α-pinene photooxidation under controlled chemical conditions – Part 2: SOA yield and composition in low- and high-NO&lt;sub&gt;x&lt;/sub&gt; environments

Chemical Mechanisms of Aging of Aerosol Formed from the Reaction ofn-Pentadecane with OH Radicals in the Presence of NOx

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α-pinene photooxidation under controlled chemical conditions – Part 2: SOA yield and composition in low- and high-NO<sub>x</sub> environments

Chemical Mechanisms of Aging of Aerosol Formed from the Reaction ofn-Pentadecane with OH Radicals in the Presence of NO_x