TY  - JOUR
A1  - Järvinen, Emma
A1  - Ignatius, Karoliina
A1  - Nichman, Leonid
A1  - Kristensen, Thomas Bjerring
A1  - Fuchs, Claudia
A1  - Hoyle, Christopher Robert
A1  - Höppel, Niko Florian
A1  - Corbin, Joel C.
A1  - Craven, Jill
A1  - Duplissy, Jonathan
A1  - Ehrhart, Sebastian
A1  - El Haddad, Imad
A1  - Frege, Carla
A1  - Gordon, Hamish
A1  - Jokinen, Tuija
A1  - Kallinger, Peter
A1  - Kirkby, Jasper
A1  - Kiselev, Alexei
A1  - Naumann, Karl-Heinz
A1  - Petäjä, Tuukka
A1  - Pinterich, Tamara
A1  - Prévôt, André Stephan Henry
A1  - Saathoff, Harald
A1  - Schiebel, Thea
A1  - Sengupta, Kamalika
A1  - Simon, Mario
A1  - Slowik, Jay G.
A1  - Tröstl, Jasmin
A1  - Virtanen, Annele
A1  - Vochezer, Paul
A1  - Vogt, Steffen
A1  - Wagner, Andrea Christine
A1  - Wagner, Robert
A1  - Williamson, Christina
A1  - Winkler, Paul M.
A1  - Yan, Chao
A1  - Baltensperger, Urs
A1  - Donahue, Neil McPherson
A1  - Flagan, Richard C.
A1  - Gallagher, Martin William
A1  - Hansel, Armin
A1  - Kulmala, Markku
A1  - Stratmann, Frank
A1  - Worsnop, Douglas R.
A1  - Möhler, Ottmar
A1  - Leisner, Thomas
A1  - Schnaiter, Martin
T1  - Observation of viscosity transition in α-pinene secondary organic aerosol
T2  - Atmospheric chemistry and physics
N2  - 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.
Y1  - 2016
UR  - http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/41891
UR  - https://nbn-resolving.org/urn:nbn:de:hebis:30:3-418910
UR  - http://www.atmos-chem-phys.net/16/4423/2016
SN  - 1680-7324
SN  - 1680-7316
N1  - © Author(s) 2016. CC Attribution 3.0 License.
VL  - 16
IS  - 7
SP  - 4423
EP  - 4438
PB  - European Geosciences Union
CY  - Katlenburg-Lindau
ER  -