Organic Peroxides in Aerosol: Key Reactive Intermediates for Multiphase Processes in the Atmosphere

Chemical Reviews, Journal Year: 2023, Volume and Issue: 123(4), P. 1635 - 1679

Published: Jan. 11, 2023

Organic peroxides (POs) are organic molecules with one or more peroxide (−O–O−) functional groups. POs commonly regarded as chemically labile termination products from gas-phase radical chemistry and therefore serve temporary reservoirs for oxidative radicals (HOx ROx) in the atmosphere. Owing to their ubiquity, active gas-particle partitioning behavior, reactivity, key reactive intermediates atmospheric multiphase processes determining life cycle (formation, growth, aging), climate, health impacts of aerosol. However, there remain substantial gaps origin, molecular diversity, fate due complex nature dynamic behavior. Here, we summarize current understanding on POs, a focus identification quantification, state-of-the-art analytical developments, molecular-level formation mechanisms, chemical transformation pathways, well environmental impacts. We find that interactions SO2 transition metal ions generally fast PO pathways liquid water, lifetimes estimated be minutes hours, while hydrolysis is particularly important α-substituted hydroperoxides. Meanwhile, photolysis thermolysis likely minor sinks POs. These distinctly different fates, such reaction OH radicals, which highlights need understand By summarizing advances remaining challenges investigation propose future research priorities regarding fate,

Language: Английский

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Role of sesquiterpenes in biogenic new particle formation

Science Advances, Journal Year: 2023, Volume and Issue: 9(36)

Published: Sept. 8, 2023

Biogenic vapors form new particles in the atmosphere, affecting global climate. The contributions of monoterpenes and isoprene to particle formation (NPF) have been extensively studied. However, sesquiterpenes received little attention despite a potentially important role due their high molecular weight. Via chamber experiments performed under atmospheric conditions, we report biogenic NPF resulting from oxidation pure mixtures β-caryophyllene, α-pinene, isoprene, which produces oxygenated compounds over wide range volatilities. We find that class termed ultralow-volatility organic (ULVOCs) are highly efficient nucleators quantitatively determine efficiency. When compared with mixture monoterpene alone, adding only 2% sesquiterpene increases ULVOC yield doubles rate. Thus, emissions need be included assessments aerosol concentrations pristine climates where is expected major source cloud condensation nuclei.

Language: Английский

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Secondary organic aerosol and organic nitrogen yields from the nitrate radical (NO<sub>3</sub>) oxidation of alpha-pinene from various RO<sub>2</sub> fates

Atmospheric chemistry and physics, Journal Year: 2022, Volume and Issue: 22(2), P. 1467 - 1482

Published: Jan. 31, 2022

Abstract. The reaction of α-pinene with NO3 is an important sink both and at night in regions mixed biogenic anthropogenic emissions; however, there debate on its importance for secondary organic aerosol (SOA) reactive nitrogen budgets the atmosphere. Previous experimental studies have generally observed low or zero SOA formation, often due to excessive [NO3] conditions. Here, we characterize formation from + as a function nitrooxy peroxy (nRO2) radical fates HO2, NO, NO3, RO2 atmospheric chamber. We show that yields are not small when nRO2 fate distribution chamber mimics atmosphere, pinene hydroperoxide (PNP) related organonitrates ambient atmosphere can be reproduced. Nearly all chemistry derives nRO2+ pathway, which alone has mass yield 56 (±7) %. Molecular composition analysis shows particulate nitrates large (60 %–70 %) portion dimer primary mechanism production under simulated nighttime Synergistic dimerization between derived ozonolysis OH oxidation also contribute should considered models. report 58 (±20) % molar PNP HO2 pathway. Applying these laboratory constraints model simulations summertime conditions southeast United States (where 80 lost via oxidation, leading 20 45 HO2), estimate 11 7 nitrate by 26 mole These results suggest significantly contributes budget likely constitutes major removal pathway boundary layer biogenic–anthropogenic areas.

Language: Английский

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Large Gas-Phase Source of Esters and Other Accretion Products in the Atmosphere

Journal of the American Chemical Society, Journal Year: 2023, Volume and Issue: 145(14), P. 7780 - 7790

Published: March 30, 2023

Dimeric accretion products have been observed both in atmospheric aerosol particles and the gas phase. With their low volatilities, they are key contributors to formation of new particles, acting as seeds for more volatile organic vapors partition onto. Many particle-phase identified esters. Various gas- pathways suggested them, yet evidence remains inconclusive. In contrast, peroxide shown form via gas-phase peroxy radical (RO2) cross reactions. Here, we show that these reactions can also be a major source esters other types products. We studied α-pinene ozonolysis using state-of-the-art chemical ionization mass spectrometry together with different isotopic labeling approaches quantum calculations, finding strong fast isomerization before accretion. Specifically, this seems happen within intermediate complex two alkoxy (RO) radicals, which generally determines branching all RO2-RO2 Accretion formed when radicals recombine. found RO suitable structures undergo extremely rapid C-C β scissions recombination, often resulting ester previously overlooked reaction pathway forming alkyl speculate some earlier identifications may fact hemiacetals or ethers. Our findings help answer several outstanding questions on sources bridge our knowledge phase particle detection As inherently stable than peroxides, impacts further reactivity aerosol.

Language: Английский

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Effects of Acidity on Reactive Oxygen Species Formation from Secondary Organic Aerosols

ACS Environmental Au, Journal Year: 2022, Volume and Issue: 2(4), P. 336 - 345

Published: April 29, 2022

Reactive oxygen species (ROS) play a critical role in the chemical transformation of atmospheric secondary organic aerosols (SOA) and aerosol health effects by causing oxidative stress vivo. Acidity is an important physicochemical property aerosols, but its on ROS formation from SOA have been poorly characterized. By applying electron paramagnetic resonance spin-trapping technique Diogenes chemiluminescence assay, we find highly distinct radical yields composition at different pH values range 1–7.4 generated oxidation isoprene, α-terpineol, α-pinene, β-pinene, toluene, naphthalene. We observe that isoprene has substantial hydroxyl (•OH) neutral pH, which are 1.5–2 times higher compared to acidic conditions total yields. Superoxide (O2•–) found be dominant all types SOAs lower pH. At α-terpineol exhibits yield carbon-centered radicals, while no observed aromatic SOA. Further experiments with model compounds show decomposition peroxide leading may suppressed due acid-catalyzed rearrangement peroxides. also 1.5–3 molar hydrogen (H2O2) biogenic SOA, likely enhanced α-hydroxyhydroperoxides quinone redox cycling, respectively. These findings bridge gap understanding mechanisms kinetics physiological environments.

Language: Английский

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Automated Reaction Kinetics of Gas-Phase Organic Species over Multiwell Potential Energy Surfaces

The Journal of Physical Chemistry A, Journal Year: 2023, Volume and Issue: 127(3), P. 565 - 588

Published: Jan. 6, 2023

Automation of rate-coefficient calculations for gas-phase organic species became possible in recent years and has transformed how we explore these complicated systems computationally. Kinetics workflow tools bring rigor speed eliminate a large fraction manual labor related error sources. In this paper give an overview quickly evolving field illustrate, through five detailed examples, the capabilities our own automated tool, KinBot. We examples from combustion atmospheric chemistry C-, H-, O-, N-atom-containing that are relevant to molecular weight growth autoxidation processes. The shed light on automation also highlight particular challenges associated with various chemical need be addressed future work.

Language: Английский

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Rates and Yields of Unimolecular Reactions Producing Highly Oxidized Peroxy Radicals in the OH-Induced Autoxidation of α-Pinene, β-Pinene, and Limonene

The Journal of Physical Chemistry A, Journal Year: 2022, Volume and Issue: 126(1), P. 88 - 100

Published: Jan. 3, 2022

Recent ambient atmospheric measurements have detected highly oxygenated organic molecules (HOMs) at many sites and are a consequence of autoxidation processes occurring temperatures. Monoterpenes in particular propensity to autoxidize although they exhibit wide range HOM yields, which may be due variety reasons including reactions with different oxidants like OH O

Language: Английский

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Global simulations of monoterpene-derived peroxy radical fates and the distributions of highly oxygenated organic molecules (HOMs) and accretion products

Atmospheric chemistry and physics, Journal Year: 2022, Volume and Issue: 22(8), P. 5477 - 5494

Published: April 26, 2022

Abstract. We evaluate monoterpene-derived peroxy radical (MT-RO2) unimolecular autoxidation and self- cross-reactions with other RO2 species in the GEOS-Chem global chemical transport model. The formation of associated highly oxygenated organic molecules (HOMs) accretion products are tracked competition bimolecular reactions. Autoxidation is dominant fate up to 6–8 km for first-generation MT-RO2, which can undergo H shifts. Reaction NO be a more common H-shift rate constants < 0.1 s−1 or at altitudes higher than 8 due imposed Arrhenius temperature dependence For MT-derived HOM-RO2, generated by multistep reaction predicted major throughout most boreal tropical forest regions, whereas dominates temperate subtropical forests Northern Hemisphere. newly added reactions result an approximate 4 % average decrease HO2 RO2, mainly faster self-/cross-reactions but impact upon HO2, OH, NOx abundances only important planetary boundary layer (PBL) over portions forests. Predicted HOM concentrations MT-rich regions seasons exceed total aerosol standard version model depending on parameters used. Comparisons observations reveal that large uncertainties remain key processes, especially respect photochemical lifetime volatility HOMs as well rates branching products. Further laboratory studies related MT-RO2-derived gas-phase product kinetics – their atmospheric fate, such gas–particle partitioning, multiphase chemistry, net secondary needed.

Language: Английский

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NO at low concentration can enhance the formation of highly oxygenated biogenic molecules in the atmosphere

Nature Communications, Journal Year: 2023, Volume and Issue: 14(1)

Published: June 8, 2023

The interaction between nitrogen monoxide (NO) and organic peroxy radicals (RO2) greatly impacts the formation of highly oxygenated molecules (HOM), key precursors secondary aerosols. It has been thought that HOM production can be significantly suppressed by NO even at low concentrations. Here, we perform dedicated experiments focusing on from monoterpenes concentrations (0 - 82 pptv). We demonstrate such enhance modulating RO2 loss favoring alkoxy continue to autoxidize through isomerization. These insights suggest yields typical boreal forest emissions vary 2.5%-6.5%, will not completely inhibited high Our findings challenge notion monotonically reduces extending knowledge RO2-NO interactions low-NO regime. This represents a major advance towards an accurate assessment budgets, especially in environments, which prevails pre-industrial atmosphere, pristine areas, upper boundary layer.

Language: Английский

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Anthropogenic Volatile Organic Compound (AVOC) Autoxidation as a Source of Highly Oxygenated Organic Molecules (HOM)

The Journal of Physical Chemistry A, Journal Year: 2021, Volume and Issue: 125(41), P. 9027 - 9039

Published: Oct. 7, 2021

Gas-phase hydrocarbon autoxidation is a rapid pathway for the production of in situ aerosol precursor compounds. It highway to molecular growth and lowering vapor pressure, it produces hydrogen-bonding functional groups that allow molecule bind into substrate. crucial process formation atmospheric secondary organic (SOA). Recently, gas-phase several volatile compounds (VOC) has been shown yield highly oxygenated molecules (HOM). Most details on HOM have obtained from biogenic monoterpenes their surrogates, with cyclic structures double bonds both found strongly facilitate formation, especially ozonolysis reactions. Similar structural features common aromatic observed high yields, despite lack appreciable O

Language: Английский

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