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| Titel |
Investigating the use of secondary organic aerosol as seed particles in simulation chamber experiments |
| VerfasserIn |
J. F. Hamilton, M. Rami Alfarra, K. P. Wyche, M. W. Ward, A. C. Lewis, G. B. McFiggans, N. Good, P. S. Monks, T. Carr, I. R. White, R. M. Purvis |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 11, no. 12 ; Nr. 11, no. 12 (2011-06-23), S.5917-5929 |
| Datensatznummer |
250009865
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| Publikation (Nr.) |
 copernicus.org/acp-11-5917-2011.pdf |
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| Zusammenfassung |
| The use of β-caryophyllene secondary organic aerosol particles as
seeds for smog chamber simulations has been investigated. A series of
experiments were carried out in the Manchester photochemical chamber as part
of the Aerosol Coupling in the Earth System (ACES) project to study the
effect of seed particles on the formation of secondary organic aerosol (SOA)
from limonene photo-oxidation. Rather than use a conventional seed aerosol
containing ammonium sulfate or diesel particles, a method was developed to
use in-situ chamber generated seed particles from β-caryophyllene
photo-oxidation, which were then diluted to a desired mass loading (in this
case 4–13 μg m−3). Limonene was then introduced into the chamber
and oxidised, with the formation of SOA seen as a growth in the size of
oxidised organic seed particles from 150 to 325 nm mean diameter. The effect
of the partitioning of limonene oxidation products onto the seed aerosol was
assessed using aerosol mass spectrometry during the experiment and the
percentage of m/z 44, an indicator of degree of oxidation, increased from
around 5 to 8 %. The hygroscopicity of the aerosol also changed, with the
growth factor for 200 nm particles increasing from less than 1.05 to 1.25 at
90 % RH. The detailed chemical composition of the limonene SOA could be
extracted from the complex β-caryophyllene matrix using
two-dimensional gas chromatography (GC × GC) and liquid chromatography
coupled to mass spectrometry. High resolution Fourier Transform Ion
Cyclotron Resonance Mass Spectrometry (FTICR-MS) was used to determine exact
molecular formulae of the seed and the limonene modified aerosol. The
average O:C ratio was seen to increase from 0.32 to 0.37 after limonene
oxidation products had condensed onto the organic seed. |
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