Tropospheric Multiphase Chemistry: Excited Triplet States Compete with OH Radicals and Singlet Molecular Oxygen

ACS Earth and Space Chemistry, Год журнала: 2025, Номер unknown

Опубликована: Фев. 12, 2025

Excited triplet states of organic molecules (3C*) present in aerosols have been investigated for their ability as oxidants the aqueous phase. Aerosols were collected Grenoble (France), winter and summer times during period December 2021 through June 2022, steady-state concentrations quantum yields 3C*, 1O2, •OH determined under solar-simulated conditions using various specific chemical probes. For comparison purposes, these three at sample 10 mg C L–1. The resulting all larger samples than ones ranked follows [1O2]ss > [3C*]ss [OH]ss agreement with previous reports. However, those do exhibit different reactivities classes compounds, which can be a generic way kOH,ORG k3C*,ORG k1O2,ORG. If we combine reactivity oxidants, it appears that matter are main most compounds. This study emphasizes relevance excited compared to singlet oxygen OH radicals need additional studies conditions.

Язык: Английский

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Formation and loss of light absorbance by phenolic aqueous SOA by ^●OH and an organic triplet excited state

Atmospheric chemistry and physics, Год журнала: 2024, Номер 24(7), С. 4473 - 4485

Опубликована: Апрель 17, 2024

Abstract. Brown carbon (BrC) is an important component of biomass-burning (BB) emissions that impacts Earth's radiation budget. BB directly emits primary BrC as well gaseous phenolic compounds (ArOH), which react in the gas and aqueous phases with oxidants – such hydroxyl radical (⚫OH) organic triplet excited states (3C∗) to form light-absorbing secondary aerosol (SOA). These reactions atmospheric phases, cloud/fog drops liquid water (ALW), SOA (aqSOA), i.e., low-volatility, high-molecular-weight products. While these are routes aqSOA formation, light absorption lifetimes formed poorly characterized. To study aspects, we monitored formation loss by produced six highly substituted phenols ⚫OH 3C∗. parent absorb very little tropospheric sunlight, they oxidized can significant amounts sunlight. The extent depends on both ArOH precursor oxidant: more from rather than ⚫OH. Under laboratory conditions, extended reaction times experiments diminish sunlight timescales hours, while 3C∗ reduce much slowly. Estimated range 3 17 h drops, where major sink, 0.7 8 ALW, sink.

Язык: Английский

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Complexities of Photosensitization in Atmospheric Particles

ACS ES&T Air, Год журнала: 2024, Номер 1(11), С. 1333 - 1351

Опубликована: Окт. 10, 2024

Brown carbons (BrCs) play a pivotal role in the light absorption by aerosol particulates exerting positive radiative forcing effect that contributes to global warming. Beyond impacts on balance, some BrCs, as photosensitizers, can generate reactive triplet-state molecules toward various atmospheric upon photoexcitation. The significance of photosensitization has been increasingly recognized, particularly context escalated wildfire incidents emit substantial BrCs. We focus complex discussing current challenges, including (1) diverse reactivities photosensitizer mixture particles, (2) methodologies for investigating processes, (3) driving factors photosensitization, and (4) typical pathways mechanisms photosensitized reactions. Lastly, we advise future research refined parametrization triplet singlet oxygen concentrations, alongside their reactivities.

Язык: Английский

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Efficient Production of Reactive Oxidants by Atmospheric Bacterial-Derived Organic Matter in the Aqueous Phase

Environmental Science & Technology, Год журнала: 2025, Номер unknown

Опубликована: Март 27, 2025

Hydroxyl radicals (•OH), singlet oxygen (1O2*), and organic triplet excited states (3C*) play key roles as oxidants ("reactive intermediates (RIs)") in forming oxidizing aqueous aerosols. Bioaerosols are ubiquitous the atmosphere, but little is known about their photochemical behavior contributions to atmospheric photochemistry. We investigated of aqueous-phase cellular matter (COM) extracellular polymeric substances (EPS) from cultured bacteria isolated PM2.5, focusing on production 3C*, 1O2*, •OH. The molecular size aromaticity chromophores fluorophores COM EPS increased with weight (MW). Apparent quantum yields (ΦRI) up 10% 5% were measured for 1O2* respectively, which upper range previously reported values. This indicated that contain photosensitizers highly efficient at producing 3C*. ΦRI concentrations ([RI]ss) decreased MW due higher-MW molecules engaging charge-transfer interactions disrupt processes oxidant production. Machine learning models used understand predict based measurable optical chemical properties EPS. study provides new insights into bioaerosols can

Язык: Английский

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Hydrogen peroxide photoformation in particulate matter and its contribution to S(IV) oxidation during winter in Fairbanks, Alaska

Atmospheric chemistry and physics, Год журнала: 2025, Номер 25(10), С. 5087 - 5100

Опубликована: Май 19, 2025

Abstract. The high levels of sulfate in wintertime particles Fairbanks, Alaska, are a subject keen research interest and regulatory concern. Recent results from the 2022 Alaska Layered Pollution And Chemical Analysis (ALPACA) field campaign indicate that roughly 40 % Fairbanks is secondary, with hydrogen peroxide (HOOH) dominant oxidant. Since formation HOOH gas phase should be negligible during ALPACA because NOx, we examined whether reactions within could significant source HOOH. To test this, collected particulate matter (PM) samples campaign, extracted them, illuminated them simulated sunlight, measured production. Aqueous extracts showed light absorption, result brown carbon (BrC) sources such as residential wood combustion. Photoformation rates PM (PMEs; normalized to winter sunlight) range 6 71 µM h−1. While absorption nearly independent pH, decrease increasing pH. Extrapolating concentrated conditions aerosol liquid water (ALW) gives an average rate in-particle ∼ 0.1 M Corresponding particle-produced 0.05–0.5 µgm-3h-1, accounting for portion secondary production rate. Our show formed makes important contribution ambient particles, even under low actinic flux typical subarctic locations like Fairbanks.

Язык: Английский

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Aqueous Oxidation of Biomass-Burning Furans by Singlet Molecular Oxygen (¹O₂*)

Environmental Science & Technology, Год журнала: 2025, Номер unknown

Опубликована: Май 22, 2025

Furans are abundant emissions from biomass burning that can react with gas-phase oxidants to produce secondary organic aerosol (SOA). might also aqueous photooxidants, such as singlet molecular oxygen (1O2*), form SOA (aqSOA), but this has not been studied. To investigate the reactivities of furans and their potential make low-volatility products, we first measured reaction kinetics for 17 furans. The resulting second-order rate constants vary widely chemical substitution, ranging 105 nearly 109 M-1 s-1. Inorganic salts decrease or enhance first-order loss by oxygen. whether furan-1O2* reactions particulate matter, mass yields three furans: furoic acid, furfuryl alcohol, 2-methylfuran-3,4-dicarboxylic acid (MFDCA). span a huge range, values ∼0, 51, 125%, respectively. Finally, estimated rates gas- aqueous-SOA formation MFDCA over range conditions, cloud fog drops liquid water. Results suggest highly substituted 1O2* could be significant source aqSOA in biomass-burning plumes triplet excited states phenols more important.

Язык: Английский

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Singlet oxygen is produced from brown carbon-containing cooking organic aerosols (BrCOA) under indoor lighting

Environmental Science Atmospheres, Год журнала: 2024, Номер 4(6), С. 611 - 619

Опубликована: Янв. 1, 2024

Indoor BrC-containing cooking organic aerosols (BrCOA) can act as sensitizers generating the first excited state of molecular oxygen, singlet under indoor lighting conditions. Sustained oxygen steady-state levels lead to prolonged oxidation impacting air quality.

Язык: Английский

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Effects of Copper on the Chemical Kinetics and Brown Carbon Formation in the Aqueous ∙OH oxidation of Phenolic Compounds

Environmental Science Processes & Impacts, Год журнала: 2024, Номер 26(9), С. 1526 - 1542

Опубликована: Янв. 1, 2024

Many phenolic compounds (PhCs) in biomass burning and fossil fuel combustion emissions can partition into atmospheric aqueous phases (

Язык: Английский

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Evaluating the secondary contribution of photosensitized chemistry to OH production in aerosols

Environmental Science Atmospheres, Год журнала: 2024, Номер 4(10), С. 1170 - 1182

Опубликована: Янв. 1, 2024

This study explores the potential contribution of secondary production OH radicals in aerosols and cloud/fog conditions arising from brown carbon (BrC) triplet state chemistry.

Язык: Английский

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