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Author(s)
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Simon, Mario (Frankfurt U.) ; Dada, Lubna (Helsinki U.) ; Heinritzi, Martin (Frankfurt U.) ; Scholz, Wiebke (Innsbruck U.) ; Stolzenburg, Dominik (Vienna U.) ; Fischer, Lukas (Innsbruck U.) ; Wagner, Andrea C (Frankfurt U. ; U. Colorado, Boulder) ; Kürten, Andreas (Frankfurt U.) ; Rörup, Birte (Helsinki U.) ; He, Xu-Cheng (Helsinki U.) ; Almeida, João (CERN ; Lisbon U.) ; Baalbaki, Rima (Helsinki U.) ; Baccarini, Andrea (PSI, Villigen) ; Bauer, Paulus S (Vienna U.) ; Beck, Lisa (Helsinki U.) ; Bergen, Anton (Frankfurt U.) ; Bianchi, Federico (Helsinki U.) ; Bräkling, Steffen (Unlisted, CH) ; Brilke, Sophia (Vienna U.) ; Caudillo, Lucia (Frankfurt U.) ; Chen, Dexian (Carnegie Mellon U.) ; Chu, Biwu (Helsinki U.) ; Dias, António ; Draper, Danielle C ; Duplissy, Jonathan ; El-Haddad, Imad ; Finkenzeller, Henning ; Frege, Carla ; Gonzalez-Carracedo, Loic ; Gordon, Hamish ; Granzin, Manuel ; Hakala, Jani (Helsinki U.) ; Hofbauer, Victoria (Carnegie Mellon U.) ; Hoyle, Christopher R (PSI, Villigen ; Zurich, ETH) ; Kim, Changhyuk (Pusan Natl. U. ; Caltech) ; Kong, Weimeng (Caltech) ; Lamkaddam, Houssni (PSI, Villigen) ; Lee, Chuan P (PSI, Villigen) ; Lehtipalo, Katrianne (Helsinki U. ; Finnish Meteorological Inst.) ; Leiminger, Markus (Innsbruck U.) ; Mai, Huajun (Caltech) ; Manninen, Hanna E (CERN) ; Marie, Guillaume (Frankfurt U.) ; Marten, Ruby (PSI, Villigen) ; Mentler, Bernhard (Innsbruck U.) ; Molteni, Ugo (PSI, Villigen) ; Nichman, Leonid (Manchester U.) ; Nie, Wei (Nanjing U.) ; Ojdanic, Andrea (Vienna U.) ; Onnela, Antti (CERN) ; Partoll, Eva (Innsbruck U.) ; Petäjä, Tuukka (Helsinki U.) ; Pfeifer, Joschka (Frankfurt U. ; CERN) ; Philippov, Maxim (Lebedev Inst.) ; Quéléver, Lauriane L J (Helsinki U.) ; Ranjithkumar, Ananth (Leeds U.) ; Rissanen, Matti P (Helsinki U. ; Tampere U. of Tech.) ; Schallhart, Simon (Helsinki U. ; Finnish Meteorological Inst.) ; Schobesberger, Siegfried (UEF, Kuopio) ; Schuchmann, Simone (CERN) ; Shen, Jiali (Helsinki U.) ; Sipilä, Mikko (Helsinki U.) ; Steiner, Gerhard (Innsbruck U.) ; Stozhkov, Yuri (Lebedev Inst.) ; Tauber, Christian (Vienna U.) ; Tham, Yee J (Helsinki U.) ; Tomé, António R (Beira Interior U., Covilha) ; Vazquez-Pufleau, Miguel (Vienna U.) ; Vogel, Alexander L (Frankfurt U. ; CERN) ; Wagner, Robert (Helsinki U.) ; Wang, Mingyi (Carnegie Mellon U.) ; Wang, Dongyu S (PSI, Villigen) ; Wang, Yonghong (Helsinki U.) ; Weber, Stefan K (CERN) ; Wu, Yusheng (Helsinki U.) ; Xiao, Mao (CERN) ; Yan, Chao (Helsinki U.) ; Ye, Penglin (Carnegie Mellon U. ; Aerodyne Research, Billerica) ; Ye, Qing (Carnegie Mellon U.) ; Zauner-Wieczorek, Marcel (Frankfurt U.) ; Zhou, Xueqin (Frankfurt U. ; PSI, Villigen) ; Baltensperger, Urs (PSI, Villigen) ; Dommen, Josef (PSI, Villigen) ; Flagan, Richard C (Caltech) ; Hansel, Armin (Innsbruck U.) ; Kulmala, Markku (Helsinki U. ; Helsinki Inst. of Phys. ; Nanjing U. ; Beijing U. of Chem. Tech.) ; Volkamer, Rainer (U. Colorado, Boulder) ; Winkler, Paul M (Vienna U.) ; Worsnop, Douglas R (Helsinki U. ; Aerodyne Research, Billerica) ; Donahue, Neil M (Carnegie Mellon U.) ; Kirkby, Jasper (Frankfurt U. ; CERN) ; Curtius, Joachim (Frankfurt U.) |
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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, gasphase 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. |