Articles | Volume 13, issue 11
Atmos. Chem. Phys., 13, 5587–5600, 2013

Special issue: The CERN CLOUD experiment (ACP/AMT inter-journal SI)

Atmos. Chem. Phys., 13, 5587–5600, 2013

Research article 06 Jun 2013

Research article | 06 Jun 2013

Evolution of particle composition in CLOUD nucleation experiments

H. Keskinen1, A. Virtanen1, J. Joutsensaari1, G. Tsagkogeorgas2, J. Duplissy3, S. Schobesberger3, M. Gysel4, F. Riccobono4, J. G. Slowik4, F. Bianchi4, T. Yli-Juuti3, K. Lehtipalo3, L. Rondo5, M. Breitenlechner6, A. Kupc7, J. Almeida5, A. Amorim8, E. M. Dunne9,10, A. J. Downard11, S. Ehrhart5, A. Franchin3, M.K. Kajos3, J. Kirkby12, A. Kürten6, T. Nieminen3, V. Makhmutov13, S. Mathot12, P. Miettinen1, A. Onnela12, T. Petäjä3, A. Praplan4, F. D. Santos8, S. Schallhart3, M. Sipilä3,14, Y. Stozhkov13, A. Tomé15, P. Vaattovaara1, D. Wimmer5, A. Prevot4, J. Dommen4, N. M. Donahue16, R.C. Flagan11, E. Weingartner4, Y. Viisanen17, I. Riipinen18, A. Hansel6,19, J. Curtius5, M. Kulmala3, D. R. Worsnop1,3,20, U. Baltensperger4, H. Wex2, F. Stratmann2, and A. Laaksonen1,17 H. Keskinen et al.
  • 1Dept. of Applied Physics, University of Eastern Finland, Kuopio, Finland
  • 2Dept. of Physics, Leibniz Institute for Tropospheric Research, Leibniz, Germany
  • 3Dept. of Physics, University of Helsinki, Helsinki, Finland
  • 4Laboratory of Atmospheric Chemistry, Paul Scherrer Institute, Villigen, Switzerland
  • 5Institute for Atmospheric and Environmental Sciences, Johann Wolfgang Goethe University Frankfurt, Frankfurt, Germany
  • 6Institute for Ion and Applied Physics, University of Innsbruck, Innsbruck, Austria
  • 7Faculty of Physics, University of Vienna, Vienna, Austria
  • 8University of Lisbon, Lisbon, Portugal
  • 9School of Earth and Environment, University of Leeds, Leeds, UK
  • 10Finnish Meteorological Institute, Kuopio, Finland
  • 11Division of Chemistry and Chemical Engineering, California Institute of Technology, California, USA
  • 12Centre européen pour la recherche nucléaire (CERN), Geneva, Switzerland
  • 13Solar and Cosmic Ray Research Laboratory, Lebedev Physical Institute, Moscow, Russia
  • 14Institute of Physics, University of Helsinki, Helsinki, Finland
  • 15University of Beira Interior, Beira, Portugal
  • 16Carnegie Mellon University, Center of Atmospheric Particle Studies, Pittsburgh, USA
  • 17Finnish Meteorological Institute, Helsinki, Finland
  • 18University of Stockholm, Stockholm, Sweden
  • 19Ionicon Analytik GmbH, Innbruck, Austria
  • 20Aerodyne Research, Billerica, Massachusetts, USA

Abstract. Sulphuric acid, ammonia, amines, and oxidised organics play a crucial role in nanoparticle formation in the atmosphere. In this study, we investigate the composition of nucleated nanoparticles formed from these compounds in the CLOUD (Cosmics Leaving Outdoor Droplets) chamber experiments at CERN (Centre européen pour la recherche nucléaire). The investigation was carried out via analysis of the particle hygroscopicity, ethanol affinity, oxidation state, and ion composition. Hygroscopicity was studied by a hygroscopic tandem differential mobility analyser and a cloud condensation nuclei counter, ethanol affinity by an organic differential mobility analyser and particle oxidation level by a high-resolution time-of-flight aerosol mass spectrometer. The ion composition was studied by an atmospheric pressure interface time-of-flight mass spectrometer. The volume fraction of the organics in the particles during their growth from sizes of a few nanometers to tens of nanometers was derived from measured hygroscopicity assuming the Zdanovskii–Stokes–Robinson relationship, and compared to values gained from the spectrometers. The ZSR-relationship was also applied to obtain the measured ethanol affinities during the particle growth, which were used to derive the volume fractions of sulphuric acid and the other inorganics (e.g. ammonium salts). In the presence of sulphuric acid and ammonia, particles with a mobility diameter of 150 nm were chemically neutralised to ammonium sulphate. In the presence of oxidation products of pinanediol, the organic volume fraction of freshly nucleated particles increased from 0.4 to ~0.9, with an increase in diameter from 2 to 63 nm. Conversely, the sulphuric acid volume fraction decreased from 0.6 to 0.1 when the particle diameter increased from 2 to 50 nm. The results provide information on the composition of nucleated aerosol particles during their growth in the presence of various combinations of sulphuric acid, ammonia, dimethylamine and organic oxidation products.

Final-revised paper