Measurements of OH and HO&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt; yields from the gas phase ozonolysis of isoprene

Malkin, T. L.; Goddard, A.; Heard, D. E.; Seakins, Paul W.

doi:10.5194/acp-10-1441-2010

Cited by 76 publications

(86 citation statements)

References 61 publications

(82 reference statements)

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“…Here, L accounts for the sum of any other chemical loss processes for SCIs in the chamber, after correction for dilution, and neglecting other (non-alkene) chemical sinks for O 3 , such as reaction with HO 2 (also produced directly during alkene ozonolysis; Alam et al, 2013;Malkin et al, 2010), which was indicated through model calculations to account for < 0.5 % of ozone loss under all the experimental conditions.…”

Section: Discussionmentioning

confidence: 99%

“…Removal of isoprene from the troposphere is dominated by reaction with the OH radical during the day and reaction with the nitrate radical during the night (Calvert et al, 2000). The ozonolysis of isoprene is also a non-photolytic source of HO x radicals (Atkinson et al, 1992;Paulson et al, 1997;Malkin et al, 2010), with measured yields of OH between 0.25 (Paulson et al, 1997) and 0.27 (Atkinson et al, 1992) Scheme 2. Mechanism of formation of the nine possible Criegee intermediates (CIs) from isoprene ozonolysis.…”

Section: Isoprene Ozonolysismentioning

confidence: 99%

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Atmospheric isoprene ozonolysis: impacts of stabilised Criegee intermediate reactions with SO2, H2O and dimethyl sulfide

et al. 2015

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Abstract. Isoprene is the dominant global biogenic volatile organic compound (VOC) emission. Reactions of isoprene with ozone are known to form stabilised Criegee intermediates (SCIs), which have recently been shown to be potentially important oxidants for SO 2 and NO 2 in the atmosphere; however the significance of this chemistry for SO 2 processing (affecting sulfate aerosol) and NO 2 processing (affecting NO x levels) depends critically upon the fate of the SCIs with respect to reaction with water and decomposition. Here, we have investigated the removal of SO 2 in the presence of isoprene and ozone, as a function of humidity, under atmospheric boundary layer conditions. The SO 2 removal displays a clear dependence on relative humidity, confirming a significant reaction for isoprene-derived SCIs with H 2 O. Under excess SO 2 conditions, the total isoprene ozonolysis SCI yield was calculated to be 0.56 (±0.03). The observed SO 2 removal kinetics are consistent with a relative rate constant, k(SCI + H 2 O) / k(SCI + SO 2 ), of 3.1 (±0.5) × 10 −5 for isoprene-derived SCIs. The relative rate constant for k(SCI decomposition) / k(SCI+SO 2 ) is 3.0 (±3.2) × 10 11 cm −3 . Uncertainties are ±2σ and represent combined systematic and precision components. These kinetic parameters are based on the simplification that a single SCI species is formed in isoprene ozonolysis, an approximation which describes the results well across the full range of experimental conditions. Our data indicate that isoprenederived SCIs are unlikely to make a substantial contribution to gas-phase SO 2 oxidation in the troposphere. We also present results from an analogous set of experiments, which show a clear dependence of SO 2 removal in the isopreneozone system as a function of dimethyl sulfide concentration. We propose that this behaviour arises from a rapid reaction between isoprene-derived SCIs and dimethyl sulfide (DMS); the observed SO 2 removal kinetics are consistent with a relative rate constant, k(SCI + DMS) / k(SCI + SO 2 ), of 3.5 (±1.8). This result suggests that SCIs may contribute to the oxidation of DMS in the atmosphere and that this process could therefore influence new particle formation in regions impacted by emissions of unsaturated hydrocarbons and DMS.

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Section: Discussionmentioning

confidence: 99%

Section: Isoprene Ozonolysismentioning

confidence: 99%

Atmospheric isoprene ozonolysis: impacts of stabilised Criegee intermediate reactions with SO2, H2O and dimethyl sulfide

et al. 2015

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“…HIRAC is a stainless steel chamber with a total volume of 2.25 m 3 , with multiple access ports used to connect an array of instrumentation and monitoring equipment (pressure gauges, thermocouples etc.). Further details on the construction can be found in Glowacki et al (2007a) and Malkin et al (2010).…”

Section: Chamber and Instrumentationmentioning

confidence: 99%

“…The instrument was used as described previously in the literature (Glowacki et al, 2007a;Malkin et al, 2010;Winiberg et al, 2015). LIF with 4026 F. A. F. Winiberg et al: Direct measurements of OH and other product yields excitation at 308 nm (A 2 + (ν = 0) ← X 2 i (ν = 0) transition) was used to probe the OH radicals directly, and the resulting fluorescence was collected via a (305 ± 5 nm) nm interference filter.…”

Section: Chamber and Instrumentationmentioning

confidence: 99%

Direct measurements of OH and other product yields from the HO2  + CH3C(O)O2 reaction

et al. 2016

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Abstract.The reaction CH 3 C(O)O 2 + HO 2 → CH 3 C(O)OOH + O 2 (Reaction R5a), CH 3 C(O)OH + O 3 (Reaction R5b), CH 3 + CO 2 + OH + O 2 (Reaction R5c) was studied in a series of experiments conducted at 1000 mbar and (293 ± 2) K in the HIRAC simulation chamber. For the first time, products, (CH 3 C(O)OOH, CH 3 C(O)OH, O 3 and OH) from all three branching pathways of the reaction have been detected directly and simultaneously. Measurements of radical precursors (CH 3 OH, CH 3 CHO), HO 2 and some secondary products HCHO and HCOOH further constrained the system. Fitting a comprehensive model to the experimental data, obtained over a range of conditions, determined the branching ratios α (R5a) = 0.37 ± 0.10, α (R5b) = 0.12 ± 0.04 and α (R5c) = 0.51 ± 0.12 (errors at 2σ level). Improved measurement/model agreement was achieved using k (R5) = (2.4 ± 0.4) × 10 −11 cm 3 molecule −1 s −1 , which is within the large uncertainty of the current IUPAC and JPL recommended rate coefficients for the title reaction. The rate coefficient and branching ratios are in good agreement with a recent study performed by Groß et al. (2014b); taken together, these two studies show that the rate of OH regeneration through Reaction (R5) is more rapid than previously thought. GEOS-Chem has been used to assess the implications of the revised rate coefficients and branching ratios; the modelling shows an enhancement of up to 5 % in OH concentrations in tropical rainforest areas and increases of up to 10 % at altitudes of 6-8 km above the equator, compared to calculations based on the IUPAC recommended rate coefficient and yield. The enhanced rate of acetylperoxy consumption significantly reduces PAN in remote regions (up to 30 %) with commensurate reductions in background NO x .

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“…Ozonolysis has been investigated in a range of studies in laboratory, chamber and field studies (Salisbury et al, 2001;Fleming et al, 2006;Sommariva et al, 2007;Kanaya et al, 1999Kanaya et al, , 2002Kanaya et al, , 2007aGeyer et al, 2003;Malkin et al, 2010;Johnson and Marston, 2008), and has been shown to be responsible for production of OH and HO 2 radicals at night (Salisbury et al, 2001;Fleming et al, 2006;Sommariva et al, 2007;Kanaya et al, 1999Kanaya et al, , 2002Kanaya et al, , 2007aEmmerson and Carslaw, 2009;Ren et al, 2003Ren et al, , 2006Volkamer et al, 2010).…”

Section: Introductionmentioning

confidence: 99%

Radical chemistry at night: comparisons between observed and modelled HOx, NO3 and N2O5 during the RONOCO project

et al. 2014

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Abstract. The RONOCO (ROle of Nighttime chemistry in controlling the Oxidising Capacity of the AtmOsphere) aircraft campaign during July 2010 and January 2011 made observations of OH, HO 2 , NO 3 , N 2 O 5 and a number of supporting measurements at night over the UK, and reflects the first simultaneous airborne measurements of these species. We compare the observed concentrations of these short-lived species with those calculated by a box model constrained by the concentrations of the longer lived species using a detailed chemical scheme. OH concentrations were below the limit of detection, consistent with model predictions. The model systematically underpredicts HO 2 by ∼ 200 % and overpredicts NO 3 and N 2 O 5 by around 80 and 50 %, respectively. Cycling between NO 3 and N 2 O 5 is fast and thus we define the NO 3x (NO 3x = NO 3 + N 2 O 5 ) family. Production of NO 3x is overwhelmingly dominated by the reaction of NO 2 with O 3 , whereas its loss is dominated by aerosol uptake of N 2 O 5 , with NO 3 + VOCs (volatile organic compounds) and NO 3 + RO 2 playing smaller roles. The production of HO x and RO x radicals is mainly due to the reaction of NO 3 with VOCs. The loss of these radicals occurs through a combination of HO 2 + RO 2 reactions, heterogeneous processes and production of HNO 3 from OH + NO 2 , with radical propagation primarily achieved through reactions of NO 3 with peroxy radicals. Thus NO 3 at night plays a similar role to both OH and NO during the day in that it both initiates RO x radical production and acts to propagate the tropospheric oxidation chain. Model sensitivity to the N 2 O 5 aerosol uptake coefficient (γ N 2 O 5 ) is discussed and we find that a value of γ N 2 O 5 = 0.05 improves model simulations for NO 3 and N 2 O 5 , but that these improvements are at the expense of model success for HO 2 . Improvements to model simulations for HO 2 , NO 3 and N 2 O 5 can be realised simultaneously on inclusion of additional unsaturated volatile organic compounds, however the nature of these compounds is extremely uncertain.

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Measurements of OH and HO<sub>2</sub> yields from the gas phase ozonolysis of isoprene

Cited by 76 publications

References 61 publications

Atmospheric isoprene ozonolysis: impacts of stabilised Criegee intermediate reactions with SO<sub>2</sub>, H<sub>2</sub>O and dimethyl sulfide

Atmospheric isoprene ozonolysis: impacts of stabilised Criegee intermediate reactions with SO<sub>2</sub>, H<sub>2</sub>O and dimethyl sulfide

Direct measurements of OH and other product yields from the HO<sub>2</sub>  + CH<sub>3</sub>C(O)O<sub>2</sub> reaction

Radical chemistry at night: comparisons between observed and modelled HO<sub>x</sub>, NO<sub>3</sub> and N<sub>2</sub>O<sub>5</sub> during the RONOCO project

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Measurements of OH and HO&lt;sub&gt;2&lt;/sub&gt; yields from the gas phase ozonolysis of isoprene

Cited by 76 publications

References 61 publications

Atmospheric isoprene ozonolysis: impacts of stabilised Criegee intermediate reactions with SO&lt;sub&gt;2&lt;/sub&gt;, H&lt;sub&gt;2&lt;/sub&gt;O and dimethyl sulfide

Atmospheric isoprene ozonolysis: impacts of stabilised Criegee intermediate reactions with SO&lt;sub&gt;2&lt;/sub&gt;, H&lt;sub&gt;2&lt;/sub&gt;O and dimethyl sulfide

Direct measurements of OH and other product yields from the HO&lt;sub&gt;2&lt;/sub&gt; + CH&lt;sub&gt;3&lt;/sub&gt;C(O)O&lt;sub&gt;2&lt;/sub&gt; reaction

Radical chemistry at night: comparisons between observed and modelled HO&lt;sub&gt;x&lt;/sub&gt;, NO&lt;sub&gt;3&lt;/sub&gt; and N&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;5&lt;/sub&gt; during the RONOCO project

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Measurements of OH and HO<sub>2</sub> yields from the gas phase ozonolysis of isoprene

Atmospheric isoprene ozonolysis: impacts of stabilised Criegee intermediate reactions with SO<sub>2</sub>, H<sub>2</sub>O and dimethyl sulfide

Atmospheric isoprene ozonolysis: impacts of stabilised Criegee intermediate reactions with SO<sub>2</sub>, H<sub>2</sub>O and dimethyl sulfide

Direct measurements of OH and other product yields from the HO<sub>2</sub>  + CH<sub>3</sub>C(O)O<sub>2</sub> reaction

Radical chemistry at night: comparisons between observed and modelled HO<sub>x</sub>, NO<sub>3</sub> and N<sub>2</sub>O<sub>5</sub> during the RONOCO project