title: Fluorescent lifetime imaging of atmospheric aerosols: a direct probe of aerosol viscosity.
abstract: The viscosity of atmospheric aerosol particles affects a number of key physical and chemical particle properties, such as composition and reactivity. However, determination of the microscopic viscosity of aerosol particles is a non-trivial task. We report a new method of imaging viscosity in a variety of model aerosol systems, based on a fluorescence lifetime determination of viscosity-sensitive fluorophores termed molecular rotors. We report the viscosity changes associated with the relative humidity dependent hygroscopicity of NaCI and sucrose aerosols, as well as reaction dependent changes in viscosity during ozonolysis of oleic acid aerosols. The Fluorescence Lifetime Imaging Microscopy (FLIM) of molecular rotors shows great promise in understanding important fundamental aerosol properties, which can be both time-dependent and spatially variable through the aerosol particle.
authors.affiliation: Department of Chemistry, Imperial College London, London SW7 2AZ, UK.
authors.forename: Neveen A
authors.initials: NA
authors.lastname: Hosny
authors.affiliation: Department of Chemistry, University of Cambridge, Cambridge CB2 1EW, UK.
authors.forename: Clare
authors.initials: C
authors.lastname: Fitzgerald
authors.affiliation: Department of Chemistry, Imperial College London, London SW7 2AZ, UK.
authors.forename: Changlun
authors.initials: C
authors.lastname: Tong
authors.affiliation: Department of Chemistry, University of Cambridge, Cambridge CB2 1EW, UK.
authors.forename: Markus
authors.initials: M
authors.lastname: Kalberer
authors.affiliation: Department of Chemistry, Imperial College London, London SW7 2AZ, UK.
authors.forename: Marina K
authors.initials: MK
authors.lastname: Kuimova
authors.affiliation: School of Geography, Earth and Environmental Science, University of Birmingham, Edgbaston B15 2TT, UK.
authors.forename: Francis D
authors.initials: FD
authors.lastname: Pope