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| Titel |
Temperature and humidity dependence of secondary organic aerosol yield from the ozonolysis of β-pinene |
| VerfasserIn |
C. Hessberg, P. Hessberg, U. Pöschl, M. Bilde, O. J. Nielsen, G. K. Moortgat |
| 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 ; 9, no. 11 ; Nr. 9, no. 11 (2009-06-04), S.3583-3599 |
| Datensatznummer |
250007353
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| Publikation (Nr.) |
 copernicus.org/acp-9-3583-2009.pdf |
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| Zusammenfassung |
| The temperature dependence of secondary organic aerosol (SOA) formation from
ozonolysis of β-pinene was studied in a flow reactor at 263 K–303 K and 1007 hPa
under dry and humid conditions (0% and 26%–68%
relative humidity, respectively). The observed SOA yields reached maximum
values of 0.18–0.39 at high particle mass concentrations (Mo). Under
dry conditions, the measurement data showed an overall increase in SOA yield
with inverse temperature, but significant oscillatory deviations from the
predicted linear increase with inverse temperature (up to 50% at high
Mo) was observed. Under humid conditions the SOA yield exhibited a
linear decrease with inverse temperature. For the atmospherically relevant
concentration level of Mo=10 μg m−3 and temperature range
263 K–293 K, the results from humid experiments in this study indicate
that the SOA yield of β-pinene ozonolysis may be well represented by
an average value of 0.15 with an uncertainty estimate of ±0.05. When
fitting the measurement data with a two-product model, both the partitioning
coefficients (Kom,i) and the stoichiometric yields (αi) of the
low-volatile and semi-volatile model species were found to vary with
temperature. The results indicate that not only the reaction product vapour
pressures but also the relative contributions of different gas-phase or
multiphase reaction channels are strongly dependent on temperature and the
presence of water vapour. In fact, the oscillatory positive temperature
dependence observed under dry conditions and the negative temperature
dependence observed under humid conditions indicate that the SOA yield is
governed much more by the temperature and humidity dependence of the
involved chemical reactions than by vapour pressure temperature
dependencies. We suggest that the elucidation and modelling of SOA formation
need to take into account the effects of temperature and humidity on the
pathways and kinetics of the involved chemical reactions as well as on the
gas-particle partitioning of the reaction products. |
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