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Observation of viscosity transition in α-pinene secondary organic aerosol

Jaervinen, Emma; Ignatius, Karoliina; Nichman, Leonid; Kristensen, Thomas B.; Fuchs, Claudia; Hoyle, Christopher R.; Hoeppel, Niko; Corbin, Joel C.; Craven, Jill; Duplissy, Jonathan; Ehrhart, Sebastian; El Haddad, Imad; Frege, Carla; Gordon, Hamish; Jokinen, Tuija; Kallinger, Peter; Kirkby, Jasper; Kiselev, Alexei; Naumann, Karl-Heinz; ... mehr



Abstract (englisch): 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 α-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 35 % at −10 °C and 80 % at −38 °C, confirming previous calculations of the viscosity-transition conditions. Consequently, α-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.


Zugehörige Institution(en) am KIT KIT-Zentrum Klima und Umwelt (Klima-Umwelt)
Institut für Meteorologie und Klimaforschung - Atmosphärische Aerosolforschung (IMK-AAF)
Publikationstyp Zeitschriftenaufsatz
Jahr 2016
Sprache Englisch
Identifikator DOI: 10.5194/acp-16-4423-2016
ISSN: 1680-7316, 1680-7324
URN: urn:nbn:de:swb:90-571233
KITopen ID: 1000057123
HGF-Programm 12.03.03; LK 01
Erschienen in Atmospheric chemistry and physics
Band 16
Heft 7
Seiten 4423-4438
Bemerkung zur Veröffentlichung Lizenz: Dieses Werk ist lizenziert unter CC BY 3.0 DE
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