Multigeneration Chemistry in Secondary Organic Aerosol Formation from Nitrate Radical Oxidation of Isoprene

ACS Earth and Space Chemistry, Journal Year: 2025, Volume and Issue: unknown

Published: Jan. 26, 2025

The nitrate radical (NO3) oxidation of isoprene is an important contributor to secondary organic aerosol (SOA). Isoprene has two double bonds which allow for multigeneration occur. effects chemistry on the gas- and particle-phase product distributions + NO3 system are not fully understood. In this study, we conduct chamber experiments by varying ratio N2O5 (precursor NO3) concentration from 1:1 14:1 investigate formation products in both phases under different levels. Multigeneration leads gas-phase then partition into particle phase depending volatility; first-generation (15–36% total SOA) such as C5H9NO5 C10H16N2O9 have volatility (log10C* = 1.0–3.0 using partitioning method log10C* 2.6–4.5 formula method) 1–5 orders magnitude higher than second-generation (37–57% SOA, −0.8–2.1 −3.7–1.8 C5H8,10N2O8, C5H9N3O10, C10H17N3O13. fast reaction rate constants (estimated be order 10–13 cm3 molecules–1 s–1 at 295 K) lower result increased SOA yields when availability increases enhanced. Specifically, increase up 300% yield observed N2O5/isoprene 3:1; 5.7% (organic mass concentration, ΔMo 4.2 μg/m3) 16.3% (ΔMo 11.9 reacted 25 ppb 3.1% 1.2 12.4% 5.4 15 ppb. maximum occurs greater or equal 3:1 a combined peroxy radicals (RO2) fate. We encourage future studies consider factors, can vary laboratory ambient conditions, comparing better understand any differences observed. Our results highlight that updated parameters including distribution should considered enable more comprehensive representation prediction atmospheric models.

Language: Английский

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Molecular composition and volatility of multi-generation products formed from isoprene oxidation by nitrate radical

Atmospheric chemistry and physics, Journal Year: 2021, Volume and Issue: 21(13), P. 10799 - 10824

Published: July 16, 2021

Abstract. Isoprene oxidation by nitrate radical (NO3) is a potentially important source of secondary organic aerosol (SOA). It suggested that the second or later-generation products are more substantial contributors to SOA. However, there few studies investigating multi-generation chemistry isoprene-NO3 reaction, and information about volatility different isoprene nitrates, which essential evaluate their potential form SOA determine atmospheric fate, rare. In this work, we studied reaction between NO3 in SAPHIR chamber (Jülich) under near-atmospheric conditions. Various were measured high-resolution time-of-flight chemical ionization mass spectrometer using Br− as reagent ion. Most detected they grouped into monomers (C4 C5 products) dimers (C10 with 1–3 groups according composition. observed match expected termination previous studies, but some compounds such three nitrogen atoms rarely reported literature gas-phase from NO3. Possible formation mechanisms for these proposed. The characterized taking advantage time behavior products. addition, vapor pressures diverse nitrates calculated parametrization methods. An estimation pressure also derived condensation behavior. According our results, belong intermediate-volatility semi-volatile thus have little effect on formation. contrast, low extremely volatility, indicating constitute 80 % total explained signals average, while contribute less than 2 %, suggesting contribution should be We expect yield 5 wall-loss- dilution-corrected concentrations, assuming all low- low-volatility compound (LVOC ELVOC) range will condense completely.

Language: Английский

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Highly oxygenated organic molecule (HOM) formation in the isoprene oxidation by NO<sub>3</sub> radical

Atmospheric chemistry and physics, Journal Year: 2021, Volume and Issue: 21(12), P. 9681 - 9704

Published: June 29, 2021

Abstract. Highly oxygenated organic molecules (HOM) are found to play an important role in the formation and growth of secondary aerosol (SOA). SOA is type with significant impact on air quality climate. Compared oxidation volatile compounds by ozone (O3) hydroxyl radical (OH), HOM nitrate (NO3), oxidant at nighttime dawn, has received less attention. In this study, reaction isoprene NO3 was investigated SAPHIR chamber (Simulation Atmospheric PHotochemistry a large Reaction chamber). A number HOM, including monomers (C5), dimers (C10), trimers (C15), both closed-shell open-shell peroxy radicals (RO2), were identified classified into various series according their formula. Their pathways proposed based observed known mechanisms literature, which further constrained time profiles after sequential addition differentiate first- second-generation products. containing one three N atoms (1–3N-monomers) formed, starting carbon double bond, forming radicals, followed autoxidation. 1N-monomers formed direct first-generation 2N-monomers (e.g., C5H8N2On(n=7–13), C5H10N2On(n=8–14)) likely termination products C5H9N2On⚫, C5-hydroxynitrate (C5H9NO4), product bond. 2N-monomers, products, dominated accounted for ∼34 % all indicating + under our experimental conditions. H shift alkoxy form subsequent autoxidation (“alkoxy–peroxy” pathway) be pathway formation. mostly accretion monomer RO2 via reactions dimer possibly C5–RO2 isoprene. RO2. The concentrations different showed distinct during reaction, linked pathway. either typical profile or combination both, multiple and/or isomers. Total molar yield estimated 1.2 %-0.7%+1.3%, corresponded ∼3.6 assuming molecular weight C5H9NO6 as lower limit. This suggests that may contribute fraction NO3.

Language: Английский

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Efficient Production of Carbonyl Sulfide in the Low‐NO_x Oxidation of Dimethyl Sulfide

Geophysical Research Letters, Journal Year: 2022, Volume and Issue: 49(3)

Published: Jan. 20, 2022

Abstract The oxidation of carbonyl sulfide (OCS) is the primary, continuous source stratospheric sulfate aerosol particles, which can scatter shortwave radiation and catalyze heterogeneous reactions in stratosphere. While it has been estimated that dimethyl (DMS), emitted from surface ocean accounts for 8%–20% global OCS source, there no existing DMS mechanism relevant to marine atmosphere consistent with an this magnitude. We describe new laboratory measurements theoretical analyses provide a mechanistic description production hydroperoxymethyl thioformate, ubiquitous, soluble product. incorporate chemical into transport model, showing factor 3 smaller than current estimates, displays maximum tropics field observations sensitive multiphase cloud chemistry.

Language: Английский

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Experimental and theoretical study on the impact of a nitrate group on the chemistry of alkoxy radicals

Physical Chemistry Chemical Physics, Journal Year: 2021, Volume and Issue: 23(9), P. 5474 - 5495

Published: Jan. 1, 2021

The chemistry of nitrated alkoxy radicals, and its impact on RO₂ measurements using the laser induced fluorescence (LIF) technique, is examined by a combined theoretical experimental study.

Language: Английский

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A Four Carbon Organonitrate as a Significant Product of Secondary Isoprene Chemistry

Geophysical Research Letters, Journal Year: 2022, Volume and Issue: 49(11)

Published: May 24, 2022

Oxidation of isoprene by nitrate radicals (NO3) or hydroxyl (OH) under high NOx conditions forms a substantial amount organonitrates (ONs). ONs impact concentrations and consequently ozone formation while also contributing to secondary organic aerosol. Here we show that the with chemical formula C4H7NO5 are significant fraction isoprene-derived ONs, based on chamber experiments ambient measurements from different sites around globe. From found isomers contribute 5%-17% all measured formed during nighttime constitute more than 40% after further daytime oxidation. In usually dominate both daytime, implying long residence time compared C5 which removed rapidly. We propose potential sources pathways, test them using box model an updated oxidation scheme.

Language: Английский

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Atmospheric Chemistry of Allylic Radicals from Isoprene: A Successive Cyclization-Driven Autoxidation Mechanism

Environmental Science & Technology, Journal Year: 2021, Volume and Issue: 55(8), P. 4399 - 4409

Published: March 26, 2021

The atmospheric chemistry of isoprene has broad implications for regional air quality and the global climate. Allylic radicals, taking 13-17% yield in oxidation by •Cl, can contribute as much 3.6-4.9% to all possible formed intermediates local regions at daytime. Considering large quantity emission, allylic radicals is therefore highly desirable. Here, we investigated mechanism using quantum chemical calculations kinetics modeling. results indicate that barrierlessly combine with O2 form peroxy (RO2•). Under ≤100 ppt NO ≤50 HO2• conditions, RO2• mainly undergo two times "successive cyclization addition" finally product fragments 2-alkoxy-acetaldehyde (C2H3O2•) 3-hydroperoxy-2-oxopropanal (C3H4O4). presented reaction illustrates a novel successive cyclization-driven autoxidation mechanism. new isomer C3H4O4 family potential aqueous-phase secondary organic aerosol precursor. >100 condition, mediate process C5H7NO3, C5H7NO7, alkoxy radical-related products. proposed advances our current understanding both RO2•.

Language: Английский

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Gas-Particle Partitioning and SOA Yields of Organonitrate Products from NO₃-Initiated Oxidation of Isoprene under Varied Chemical Regimes

ACS Earth and Space Chemistry, Journal Year: 2021, Volume and Issue: 5(4), P. 785 - 800

Published: March 11, 2021

Alkyl nitrate (AN) and secondary organic aerosol (SOA) from the reaction of radicals (NO3) with isoprene were observed in Simulation Atmospheric PHotochemistry In a large Reaction (SAPHIR) chamber during NO3Isop campaign August 2018. Based on 15 day-long experiments under various conditions, we conclude that has nominally unity molar AN yield (observed range 90 ± 40%) an SOA mass OA + 13–15% (with ∼50 μg m–3 inorganic seed 2–5 total aerosol). Isoprene (5–25 ppb) oxidant (typically ∼100 ppb O3 5–25 NO2) concentrations composition (inorganic coating) varied while remaining close to ambient producing similar yields all regimes. We observe formation dinitrates upon oxidation second double bond only once precursor is fully consumed. determine bulk partitioning coefficient for ANs (Kp ∼ 10–3 m3 μg–1), indicating average volatility corresponding C5 hydroxy hydroperoxy nitrate.

Language: Английский

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Nitrate radical formation and reaction with limonene by TiO2 photocatalysis: A kinetic study

Catalysis Today, Journal Year: 2024, Volume and Issue: 432, P. 114600 - 114600

Published: Feb. 21, 2024

Language: Английский

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Atmospheric Autoxidation of Organophosphate Esters

Environmental Science & Technology, Journal Year: 2021, Volume and Issue: 56(11), P. 6944 - 6955

Published: Nov. 18, 2021

Organophosphate esters (OPEs), widely used as flame retardants and plasticizers, have frequently been identified in the atmosphere. However, their atmospheric fate toxicity associated with transformations are unclear. Here, we performed quantum chemical calculations computational toxicology to investigate reaction mechanism of peroxy radicals OPEs (OPEs-RO2•), key intermediates determining chemistry OPEs, products. TMP-RO2• (R1) TCPP-RO2• (R2) derived from trimethyl phosphate tris(2-chloroisopropyl) phosphate, respectively, selected model systems. The results indicate that R1 R2 can follow an H-shift-driven autoxidation under low NO concentration ([NO]) conditions, clarifying RO2• mechanism. unexpected be attributed distinct role ─(O)3P(═O) phosphate-ester group facilitating H-shift OPEs-RO2• commonly encountered ─OC(═O)─ ─ONO2 ester groups Under high [NO] mediate form organonitrates alkoxy radical-related products volatility aquatic compared corresponding parent compounds. proposed advances our current understanding environmental risk OPEs.

Language: Английский

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