| Autor: |
Krasnomowitz, Justin M., Apsokardu, Michael J., Stangl, Christopher M., Tiszenkel, Lee, Ouyang, Qi, Lee, Shanhu, Johnston, Murray V. |
| Předmět: |
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| Zdroj: |
Aerosol Science & Technology; Apr2019, Vol. 53 Issue 4, p406-418, 13p |
| Abstrakt: |
The fraction of Aitken mode particles that grow sufficiently large to act as cloud condensation nuclei is an important factor in understanding the climate impact of atmospheric particles. Elucidating the rate of particle growth in this size range requires a detailed understanding of the mechanisms by which these particles grow. Here, a flow tube reactor is described, characterized and then used to study growth of ammonium sulfate seed particles in the Aitken mode size range by α-pinene ozonolysis under dry conditions (10% RH). When size-selected particles starting at 40, 60, or 80 nm diameter were exposed to α-pinene (11 ppbv) and ozone (five separate mixing ratios between 30 and 250 ppbv), particle growth was found to depend on the amount of α-pinene reacted and the condensation sink, but not directly dependent on the initial seed particle diameter. The observed dependencies are consistent with a condensational growth mechanism, which is not surprising since the dry conditions of the experiment minimized the probability of multiphase chemistry within the seed particles. Combining the measured particle growth with a kinetic model gave a molar yield of 13% for condensable organic molecules produced by the ozonolysis reaction. This value is somewhat higher than previously reported molar yields of highly oxidized molecules (HOMs) measured in the gas phase with chemical ionization mass spectrometry, which are in the 3-7% range. The relationship between molar yields determined from gas phase and particle phase measurements is discussed. Copyright © 2019 American Association for Aerosol Research [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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