Molecular understanding of new-particle formation from alpha-pinene between -50 °C and 25 °C

Autor(en)

M. Simon, L. Dada, M. Heinritzi, W. Scholz, D. Stolzenburg, L. Fischer, A. C. Wagner, A. Kürten, Birte Rörup, Xu-Cheng He, J. Almeida, R. Baalbaki, A. Baccarini, Paulus S. Bauer, L. Beck, A. Bergen, F. Bianchi, S. Bräkling, S. Brilke, L. Caudillo, D. Chen, B. Chu, A. Dias, D. C. Draper, Jonathan Duplissy, I. El Haddad, H. Finkenzeller, C. Frege, L. Gonzalez-Carracedo, H. Gordon, M. Granzin, J. Hakala, V. Hofbauer, C. R. Hoyle, C. Kim, W. Kong, H. Lamkaddam, C. P. Lee, K. Lehtipalo, M. Leiminger, H. Mai, H. E. Manninen, G. Marie, R. Marten, B. Mentler, U. Molteni, L. Nichman, W. Nie, A. Ojdanic, A. Onnela, E. Partoll, T. Petäjä, J. Pfeifer, M. Philippov, L. L. J. Quéléver, A. Ranjithkumar, M. Rissanen, Simon Schallhart, S. Schobesberger, S. Schuchmann, Jiali Shen, M. Sipilä, Gerhard Steiner, Y. Stozhkov, Christian Tauber, Yee J. Tham, A. R. Tomé, Miguel Vazquez-Pufleau, A. L. Vogel, R. Wagner, M. Wang, D. S. Wang, Y. Wang, S. K. Weber, Y. Wu, M. Xiao, Chao Yan, P. Ye, Q. Ye, M. Zauner-Wieczorek, X. Zhou, U. Baltensperger, J. Dommen, R. C. Flagan, A. Hansel, M. Kulmala, R. Volkamer, Paul M. Winkler, D. R. Worsnop, N. M. Donahue, J. Kirkby, J. Curtius

Abstrakt

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.

Organisation(en)

Aerosolphysik und Umweltphysik

Externe Organisation(en)

Leopold-Franzens-Universität Innsbruck, University of Helsinki, Johann Wolfgang Goethe-Universität Frankfurt am Main, European Organization for Nuclear Research (CERN), IONICON Analytik GmbH, University of Colorado, Boulder, Universidade de Lisboa, Paul Scherrer Institute, Tofwerk AG, Carnegie Mellon University, University of California, Irvine, Eidgenössische Technische Hochschule Zürich, Pusan National University (PNU), California Institute of Technology (Caltech), Finnish Meteorological Institute, University of Manchester, Nanjing University, Russian Academy of Sciences, University of Leeds, University of Tampere, University of Eastern Finland, Universidade da Beira Interior, Aerodyne Res Inc, Beijing University of Chemical Technology

Journal

Atmospheric Chemistry and Physics

Band

20

Seiten

9183–9207

Anzahl der Seiten

25

ISSN

1680-7316

DOI

https://doi.org/10.5194/acp-2019-1058

Publikationsdatum

2019

Peer-reviewed

Ja

ÖFOS 2012

103037 Umweltphysik, 103039 Aerosolphysik

Schlagwörter

ASJC Scopus Sachgebiete

Atmospheric Science

Link zum Portal

https://ucrisportal.univie.ac.at/de/publications/bbcab3ba-9e8e-4e31-b147-2bb05f4053e7