Experimental investigation into the volatilities of highly oxygenated organic molecules (HOMs)

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dc.contributor University of Helsinki, Institute for Atmospheric and Earth System Research (INAR) en
dc.contributor University of Helsinki, INAR Physics en
dc.contributor University of Helsinki, INAR Physics en
dc.contributor University of Helsinki, Institute for Atmospheric and Earth System Research (INAR) en
dc.contributor.author Peräkylä, Otso
dc.contributor.author Riva, Matthieu
dc.contributor.author Heikkinen, Liine
dc.contributor.author Quelever, Lauriane
dc.contributor.author Roldin, Pontus
dc.contributor.author Ehn, Mikael
dc.date.accessioned 2020-04-14T14:30:01Z
dc.date.available 2020-04-14T14:30:01Z
dc.date.issued 2020-01-20
dc.identifier.citation Peräkylä , O , Riva , M , Heikkinen , L , Quelever , L , Roldin , P & Ehn , M 2020 , ' Experimental investigation into the volatilities of highly oxygenated organic molecules (HOMs) ' , Atmospheric Chemistry and Physics , vol. 20 , no. 2 , pp. 649-669 . https://doi.org/10.5194/acp-20-649-2020 en
dc.identifier.issn 1680-7316
dc.identifier.other PURE: 135358348
dc.identifier.other PURE UUID: 049a56da-db91-4d6c-a82f-e316013589c9
dc.identifier.other WOS: 000508207500002
dc.identifier.other ORCID: /0000-0001-7837-967X/work/72305736
dc.identifier.other ORCID: /0000-0002-2089-0106/work/72305799
dc.identifier.uri http://hdl.handle.net/10138/313988
dc.description.abstract Secondary organic aerosol (SOA) forms a major part of the tropospheric submicron aerosol. Still, the exact formation mechanisms of SOA have remained elusive. Recently, a newly discovered group of oxidation products of volatile organic compounds (VOCs), highly oxygenated organic molecules (HOMs), have been proposed to be responsible for a large fraction of SOA formation. To assess the potential of HOMs to form SOA and to even take part in new particle formation, knowledge of their exact volatilities is essential. However, due to their exotic, and partially unknown, structures, estimating their volatility is challenging. In this study, we performed a set of continuous flow chamber experiments, supported by box modelling, to study the volatilities of HOMs, along with some less oxygenated compounds, formed in the ozonolysis of α-pinene, an abundant VOC emitted by boreal forests. Along with gaseous precursors, we periodically injected inorganic seed aerosol into the chamber to vary the condensation sink (CS) of low-volatility vapours. We monitored the decrease of oxidation products in the gas phase in response to increasing CS, and were able to relate the responses to the volatilities of the compounds. We found that HOM monomers are mainly of low volatility, with a small fraction being semi-volatile. HOM dimers were all at least low volatility, but probably extremely low volatility; however, our method is not directly able to distinguish between the two. We were able to model the volatility of the oxidation products in terms of their carbon, hydrogen, oxygen and nitrogen numbers. We found that increasing levels of oxygenation correspond to lower volatilities, as expected, but that the decrease is less steep than would be expected based on many existing models for volatility, such as SIMPOL. The hydrogen number of a compound also predicted its volatility, independently of the carbon number, with higher hydrogen numbers corresponding to lower volatilities. This can be explained in terms of the functional groups making up a molecule: high hydrogen numbers are associated with, e.g. hydroxy groups, which lower volatility more than, e.g. carbonyls, which are associated with a lower hydrogen number. The method presented should be applicable to systems other than α-pinene ozonolysis, and with different organic loadings, in order to study different volatility ranges. fi
dc.format.extent 21
dc.language.iso eng
dc.relation.ispartof Atmospheric Chemistry and Physics
dc.rights en
dc.subject 114 Physical sciences en
dc.title Experimental investigation into the volatilities of highly oxygenated organic molecules (HOMs) en
dc.type Article
dc.description.version Peer reviewed
dc.identifier.doi https://doi.org/10.5194/acp-20-649-2020
dc.type.uri info:eu-repo/semantics/other
dc.type.uri info:eu-repo/semantics/publishedVersion
dc.contributor.pbl
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