Observation of viscosity transition in alpha-pinene secondary organic aerosol

Autoren:Jaervinen, Emma (Karlsruher Institut für Technologie); Ignatius, Karoliina (Inst Tropospher Res TROPOS); Nichman, Leonid (University of Manchester); Kristensen, Thomas B. (Inst Tropospher Res TROPOS); Fuchs, Claudia (Paul Scherrer Institute); Hoyle, Christopher R. (Paul Scherrer Institute); Hoeppel, Niko (Karlsruher Institut für Technologie); Corbin, Joel C. (Paul Scherrer Institute); Craven, Jill (California Institute of Technology (Caltech)); Duplissy, Jonathan (University of Helsinki); Ehrhart, Sebastian (European Organization for Nuclear Research (CERN)); El Haddad, Imad (Paul Scherrer Institute); Frege, Carla (Paul Scherrer Institute); Gordon, Hamish (European Organization for Nuclear Research (CERN)); Jokinen, Tuija (University of Helsinki); Kallinger, Peter; Kirkby, Jasper (European Organization for Nuclear Research (CERN)); Kiselev, Alexei (Karlsruher Institut für Technologie); Naumann, Karl-Heinz (Karlsruher Institut für Technologie); Petaja, Tuukka (University of Helsinki); Pinterich, Tamara; Prevot, Andre S. H. (Paul Scherrer Institute); Saathoff, Harald (Karlsruher Institut für Technologie); Schiebel, Thea (Karlsruher Institut für Technologie); Sengupta, Kamalika (University of Leeds); Simon, Mario (Johann Wolfgang Goethe-Universität Frankfurt am Main); Slowik, Jay G. (Paul Scherrer Institute); Troestl, Jasmin (Paul Scherrer Institute); Virtanen, Annele (University of Eastern Finland); Vochezer, Paul (Karlsruher Institut für Technologie); Vogt, Steffen (Karlsruher Institut für Technologie); Wagner, Andrea C. (Johann Wolfgang Goethe-Universität Frankfurt am Main); Wagner, Robert (Karlsruher Institut für Technologie); Williamson, Christina (Johann Wolfgang Goethe-Universität Frankfurt am Main); Winkler, Paul M.; Yan, Chao (University of Helsinki); Baltensperger, Urs (Paul Scherrer Institute); Donahue, Neil M. (Carnegie Mellon University); Flagan, Rick C. (California Institute of Technology (Caltech)); Gallagher, Martin (University of Manchester); Hansel, Armin (Leopold-Franzens-Universität Innsbruck); Kulmala, Markku (University of Helsinki); Stratmann, Frank (Inst Tropospher Res TROPOS); Worsnop, Douglas R. (Aerodyne Res Inc); Moehler, Ottmar (Karlsruher Institut für Technologie); Leisner, Thomas (Karlsruher Institut für Technologie); Schnaiter, Martin (Karlsruher Institut für Technologie)
Abstrakt:Under certain conditions, secondary organic aerosol (SOA) particles can exist in the atmosphere in an amorphous solid or semi-solid state. To determine their relevance to processes such as ice nucleation or chemistry occurring within particles requires knowledge of the temperature and relative humidity (RH) range for SOA to exist in these states. In the Cosmics Leaving Outdoor Droplets (CLOUD) experiment at The European Organisation for Nuclear Research (CERN), we deployed a new in situ optical method to detect the viscous state of alpha-pinene SOA particles and measured their transition from the amorphous highly viscous state to states of lower viscosity. The method is based on the depolarising properties of laboratory-produced non-spherical SOA particles and their transformation to non-depolarising spherical particles at relative humidities near the deliquescence point. We found that particles formed and grown in the chamber developed an asymmetric shape through coagulation. A transition to a spherical shape was observed as the RH was increased to between 35aEuro-% at -10aEuro-A degrees C and 80aEuro-% at -38aEuro-A degrees C, confirming previous calculations of the viscosity-transition conditions. Consequently, alpha-pinene SOA particles exist in a viscous state over a wide range of ambient conditions, including the cirrus region of the free troposphere. This has implications for the physical, chemical, and ice-nucleation properties of SOA and SOA-coated particles in the atmosphere.
Anzahl der Seiten:16
Journaltitel:Atmospheric Chemistry and Physics
Peer reviewed:true
Digital Object Identifier (DOI):http://dx.doi.org/10.5194/acp-16-4423-2016