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Published May 26, 2016 | Published + Supplemental Material
Journal Article Open

Ion-induced nucleation of pure biogenic particles


Atmospheric aerosols and their effect on clouds are thought to be important for anthropogenic radiative forcing of the climate, yet remain poorly understood. Globally, around half of cloud condensation nuclei originate from nucleation of atmospheric vapours. It is thought that sulfuric acid is essential to initiate most particle formation in the atmosphere, and that ions have a relatively minor role. Some laboratory studies, however, have reported organic particle formation without the intentional addition of sulfuric acid, although contamination could not be excluded. Here we present evidence for the formation of aerosol particles from highly oxidized biogenic vapours in the absence of sulfuric acid in a large chamber under atmospheric conditions. The highly oxygenated molecules (HOMs) are produced by ozonolysis of α-pinene. We find that ions from Galactic cosmic rays increase the nucleation rate by one to two orders of magnitude compared with neutral nucleation. Our experimental findings are supported by quantum chemical calculations of the cluster binding energies of representative HOMs. Ion-induced nucleation of pure organic particles constitutes a potentially widespread source of aerosol particles in terrestrial environments with low sulfuric acid pollution.

Additional Information

© 2016 Macmillan Publishers Limited. This work is licensed under a Creative Commons Attribution 4.0 International (CC BY 4.0) licence. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in the credit line; if the material is not included under the Creative Commons licence, users will need to obtain permission from the licence holder to reproduce the material. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/. Received 06 July 2015; Accepted 16 March 2016; Published online 25 May 2016. We thank CERN for supporting CLOUD with important technical and financial resources, and for providing a particle beam from the CERN Proton Synchrotron. We also thank P. Carrie, L.-P. De Menezes, J. Dumollard, F. Josa, I. Krasin, R. Kristic, A. Laassiri, O. S. Maksumov, B. Marichy, H. Martinati, S. V. Mizin, R. Sitals, A. Wasem and M. Wilhelmsson for their contributions to the experiment. We thank the CSC Centre for Scientific Computing in Espoo, Finland for computer time. This research has received funding from the EC Seventh Framework Programme (Marie Curie Initial Training Network MC-ITN CLOUD-TRAIN no. 316662, EU Horizon 2020 Marie Curie grant no. 656994, ERC-Consolidator grant NANODYNAMITE no. 616075 and ERC-Advanced grant ATMNUCLE no. 227463), the German Federal Ministry of Education and Research (project no. 01LK1222A), the Swiss National Science Foundation (project nos 200020_135307, 200021_140663, 206021_144947/1 and 20FI20_149002/1), the Academy of Finland (Center of Excellence project no. 1118615), the Academy of Finland (135054, 133872, 251427, 139656, 139995, 137749, 141217, 141451), the Finnish Funding Agency for Technology and Innovation, the Väisälä Foundation, the Nessling Foundation, the Austrian Science Fund (FWF; project no. L593), the Portuguese Foundation for Science and Technology (project no. CERN/FP/116387/2010), the Swedish Research Council, Vetenskapsrådet (grant 2011-5120), the Presidium of the Russian Academy of Sciences and Russian Foundation for Basic Research (grant 12-02-91522-CERN), the UK Natural Environment Research Council (grant NE/K015966/1), the Royal Society (Wolfson Merit Award), the US National Science Foundation (grants AGS1136479, AGS1447056 and CHE1012293), Caltech ESE Grant (Davidow Foundation), Dreyfus Award EP-11-117, the French National Research Agency (ANR), the Nord-Pas de Calais, and the European Funds for Regional Economic Development (FEDER, Labex-Cappa, ANR-11-LABX-0005-01). Author Contributions: J.A., H.G., A.K., T.N., J.T. and C.W. analysed the nucleation rates; C.Fr. analysed the APi-TOF charged clusters; M.H., M.Sim. and C.Y. performed the CI-APi-TOF HOM and H2SO4 analyses; A.-K.B. analysed the PTR-TOF α-pinene; J.H.S. and X.Z. analysed the ELVOC structures and formation mechanisms; I.K.O. performed the quantum chemical calculations; A.Ad., J.A., A.Am., A.-K.B., F.B., M.B., S.B., J.Cu., J.Cr., A.D., J.Do., J.Du., S.E., C.Fr., C.Fu., H.G., M.H., C.R.H., T.J., H.J., J.Ka., J. Kim, J.Kir., M.Kr., A.K., K.L., V.M., U.M., T.N., F.P., T.P., A.P.P., M.P.R., N.S., K.S., M.Sim., M.Sip., G.S., A.T., J.T., A.W., D.W., R.W., C.W., C.Y. and P.Y. collected the data and contributed to the analysis; K.S.C., H.G., K.P., A.R., N.A.D.R., K.S. and C.E.S. evaluated the atmospheric relevance; J.Kir. wrote the manuscript; J.A., J.Do., N.M.D., C.Fr., H.G., M.H., J.H.S., M.Sim., C.W., R.W., C.Y. and X.Z. contributed to Methods and Extended Data; and U.B., K.S.C., J.Cu., J.Do., N.M.D., R.C.F., A.H., J.Kir., M.Ku., J.H.S. and D.R.W. contributed to data interpretation and editing of manuscript. All authors contributed to the development of the CLOUD facility and analysis instruments, and commented on the manuscript. The authors declare no competing financial interests.

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