1. Institute for Atmospheric and Environmental Sciences, Goethe-University Frankfurt, 60438 Frankfurt am Main, Germany
2. Aerosol and Haze Laboratory, Beijing Advanced Innovation Center for Soft Matter Science and Engineering, Beijing University of Chemical Technology, 100029 Beijing, P. R. China
3. Institute for Atmospheric and Earth System Research/Physics, Faculty of Science, University of Helsinki, 00014 Helsinki, Finland
4. Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, 100085 Beijing, P. R. China
5. Laboratory of Atmospheric Chemistry, Paul Scherrer Institute, 5232 Villigen, Switzerland