Rapid formation of aerosol precursors from the autoxidation of aromatic carbonyls and the remarkable enhancing influence of NO addition

Rapid formation of aerosol precursors from the autoxidation of aromatic carbonyls and the remarkable enhancing influence of NO addition | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Article Rapid formation of aerosol precursors from the autoxidation of aromatic carbonyls and the remarkable enhancing influence of NO addition Shawon Barua, Avinash Kumar, Prasenjit Seal, Mojtaba Bezaatpour, and 4 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7332278/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted You are reading this latest preprint version Abstract Aromatic carbonyl compounds are common constituents of urban atmospheres. Their rapid oxidation yields highly oxygenated organic molecules (HOMs) that are key direct secondary organic aerosol (SOA) precursors in ambient air. However, the formation of HOM and SOA is thought to be suppressed by high NOx (NO + NO2) concentrations, typical of polluted environments. Furthermore, the vast diversity of gaseous hydrocarbons and their reactivity leads to uncertainties in the net effect of NOx on oxidation processes. Here, we investigate the OH initiated oxidation of three aromatic carbonyls, benzaldehyde, phenylacetaldehyde, and acetophenone in variable reaction time experiments (0.9 s to 14 s) in a flow tube reactor coupled to a nitrate chemical ionization mass spectrometer (NO3– CIMS). We observe HOMs with 12 O atoms from phenylacetaldehyde within 0.9 s while benzaldehyde and acetophenone produce HOMs with 10 and 11 O atoms within 1.1 s and 2.7 s, respectively. Remarkably, our experiments with varying high NO concentrations (10 ppb to 1 ppm) at 14 s reaction time show that phenylacetaldehyde and acetophenone HOM yields are enhanced by a factor of up to 16.9 for O8 HOMs, starkly contrasting the traditional understanding of oxidation suppression by NOx. We use quantum chemical methods to characterize the relevant aromatic carbonyl autoxidation mechanisms, which suggest that OH addition is key to the observed rapid molecular functionalization. The fastest formation of HOM from phenylacetaldehyde is in agreement with our calculations and our kinetic simulations at atmospherically relevant conditions. We also determine theoretical saturation concentrations of the measured HOMs and note that production of low to extremely-low volatility compounds is considerably enhanced in presence of NO. This observation represents a significant advancement in our understanding of polluted air and will aid in accurate estimation of HOM and secondary aerosol budgets, especially in high NOx environments. Earth and environmental sciences/Climate sciences/Atmospheric science Physical sciences/Chemistry/Physical chemistry Full Text Additional Declarations There is NO Competing Interest. Supplementary Files SupportingInformation.pdf Rapid formation of aerosol precursors from the autoxidation of aromatic carbonyls and the remarkable enhancing influence of NO addition Cite Share Download PDF Status: Under Review Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-7332278","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":506748186,"identity":"9ed5bee9-291a-478a-93f1-6d7957aaa176","order_by":0,"name":"Shawon 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Their rapid oxidation yields highly oxygenated organic molecules (HOMs) that are key direct secondary organic aerosol (SOA) precursors in ambient air. However, the formation of HOM and SOA is thought to be suppressed by high NOx (NO + NO2) concentrations, typical of polluted environments. Furthermore, the vast diversity of gaseous hydrocarbons and their reactivity leads to uncertainties in the net effect of NOx on oxidation processes. Here, we investigate the OH initiated oxidation of three aromatic carbonyls, benzaldehyde, phenylacetaldehyde, and acetophenone in variable reaction time experiments (0.9 s to 14 s) in a flow tube reactor coupled to a nitrate chemical ionization mass spectrometer (NO3– CIMS). We observe HOMs with 12 O atoms from phenylacetaldehyde within 0.9 s while benzaldehyde and acetophenone produce HOMs with 10 and 11 O atoms within 1.1 s and 2.7 s, respectively. Remarkably, our experiments with varying high NO concentrations (10 ppb to 1 ppm) at 14 s reaction time show that phenylacetaldehyde and acetophenone HOM yields are enhanced by a factor of up to 16.9 for O8 HOMs, starkly contrasting the traditional understanding of oxidation suppression by NOx. We use quantum chemical methods to characterize the relevant aromatic carbonyl autoxidation mechanisms, which suggest that OH addition is key to the observed rapid molecular functionalization. The fastest formation of HOM from phenylacetaldehyde is in agreement with our calculations and our kinetic simulations at atmospherically relevant conditions. We also determine theoretical saturation concentrations of the measured HOMs and note that production of low to extremely-low volatility compounds is considerably enhanced in presence of NO. This observation represents a significant advancement in our understanding of polluted air and will aid in accurate estimation of HOM and secondary aerosol budgets, especially in high NOx environments.","manuscriptTitle":"Rapid formation of aerosol precursors from the autoxidation of aromatic carbonyls and the remarkable enhancing influence of NO addition","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-08-29 06:59:12","doi":"10.21203/rs.3.rs-7332278/v1","editorialEvents":[],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"nature-communications","isNatureJournal":true,"hasQc":false,"allowDirectSubmit":false,"externalIdentity":"NCOMMS","sideBox":"Learn more about [Nature Communications](http://www.nature.com/ncomms/)","snPcode":"","submissionUrl":"https://mts-ncomms.nature.com/","title":"Nature Communications","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"ejp","reportingPortfolio":"Nature Communications","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"187bac8c-4023-4d8c-9ce9-4466f554e736","owner":[],"postedDate":"August 29th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[{"id":53822818,"name":"Earth and environmental sciences/Climate sciences/Atmospheric science"},{"id":53822819,"name":"Physical sciences/Chemistry/Physical chemistry"}],"tags":[],"updatedAt":"2026-04-21T10:15:31+00:00","versionOfRecord":[],"versionCreatedAt":"2025-08-29 06:59:12","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-7332278","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7332278","identity":"rs-7332278","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}