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dc.contributor.author
Simon, Mario
dc.contributor.author
Hoyle, Christopher R.
dc.contributor.author
et al.
dc.date.accessioned
2020-08-24T11:55:28Z
dc.date.available
2020-08-21T03:17:27Z
dc.date.available
2020-08-24T11:55:28Z
dc.date.issued
2020
dc.identifier.issn
1680-7375
dc.identifier.issn
1680-7367
dc.identifier.other
10.5194/acp-20-9183-2020
en_US
dc.identifier.uri
http://hdl.handle.net/20.500.11850/432182
dc.identifier.doi
10.3929/ethz-b-000432182
dc.description.abstract
Highly oxygenated organic molecules (HOMs) contribute substantially to the formation and growth of atmospheric aerosol particles, which affect air quality, human health and Earth's climate. HOMs are formed by rapid, gas-phase autoxidation of volatile organic compounds (VOCs) such as α-pinene, the most abundant monoterpene in the atmosphere. Due to their abundance and low volatility, HOMs can play an important role in new-particle formation (NPF) and the early growth of atmospheric aerosols, even without any further assistance of other low-volatility compounds such as sulfuric acid. Both the autoxidation reaction forming HOMs and their NPF rates are expected to be strongly dependent on temperature. However, experimental data on both effects are limited. Dedicated experiments were performed at the CLOUD (Cosmics Leaving OUtdoor Droplets) chamber at CERN to address this question. In this study, we show that a decrease in temperature (from +25 to −50 ∘C) results in a reduced HOM yield and reduced oxidation state of the products, whereas the NPF rates (J1.7 nm) increase substantially. Measurements with two different chemical ionization mass spectrometers (using nitrate and protonated water as reagent ion, respectively) provide the molecular composition of the gaseous oxidation products, and a two-dimensional volatility basis set (2D VBS) model provides their volatility distribution. The HOM yield decreases with temperature from 6.2 % at 25 ∘C to 0.7 % at −50 ∘C. However, there is a strong reduction of the saturation vapor pressure of each oxidation state as the temperature is reduced. Overall, the reduction in volatility with temperature leads to an increase in the nucleation rates by up to 3 orders of magnitude at −50 ∘C compared with 25 ∘C. In addition, the enhancement of the nucleation rates by ions decreases with decreasing temperature, since the neutral molecular clusters have increased stability against evaporation. The resulting data quantify how the interplay between the temperature-dependent oxidation pathways and the associated vapor pressures affect biogenic NPF at the molecular level. Our measurements, therefore, improve our understanding of pure biogenic NPF for a wide range of tropospheric temperatures and precursor concentrations.
en_US
dc.format
application/pdf
en_US
dc.language.iso
en
en_US
dc.publisher
Copernicus
en_US
dc.rights.uri
http://creativecommons.org/licenses/by/4.0/
dc.title
Molecular understanding of new-particle formation from <i>α</i>-pinene between -50 and +25 °C
en_US
dc.type
Journal Article
dc.rights.license
Creative Commons Attribution 4.0 International
dc.date.published
2020-08-03
ethz.journal.title
Atmospheric Chemistry and Physics
ethz.journal.volume
20
en_US
ethz.journal.issue
15
en_US
ethz.journal.abbreviated
Atmos. chem. phys.
ethz.pages.start
9183
en_US
ethz.pages.end
9207
en_US
ethz.version.deposit
publishedVersion
en_US
ethz.grant
Investigation of new particle formation in the CLOUD chamber at CERN and the PSI smog chamber
en_US
ethz.identifier.wos
ethz.identifier.scopus
ethz.publication.place
Göttingen
en_US
ethz.publication.status
published
en_US
ethz.grant.agreementno
152907
ethz.grant.fundername
SNF
ethz.grant.funderDoi
10.13039/501100001711
ethz.grant.program
Projektförderung in Mathematik, Natur- und Ingenieurwissenschaften (Abteilung II)
ethz.date.deposited
2020-08-21T03:17:33Z
ethz.source
SCOPUS
ethz.eth
yes
en_US
ethz.availability
Open access
en_US
ethz.rosetta.installDate
2020-08-24T11:55:40Z
ethz.rosetta.lastUpdated
2021-02-15T16:39:44Z
ethz.rosetta.exportRequired
true
ethz.rosetta.versionExported
true
ethz.COinS
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