Heidelberg 2015 – scientific programme

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UP: Fachverband Umweltphysik

UP 4: Postersession Atmosphäre

UP 4.16: Poster

Wednesday, March 25, 2015, 10:45–19:45, G/Foyer

Mie resonance spectroscopy of levitated ternary organic/ammonium sulfate (AS)/water aerosol particles — •Andreas Peckhaus¹ and Ulrich Krieger² — ¹Karlsruher Institut für Technologie (KIT), Karlsruhe, Deutschland — ²Institut für Atmosphäre und Klima (IAC), ETH Zürich, Schweiz

The occurrence of liquid-liquid phase separation (LLPS) in internally mixed ternary C6/AS/H2O aerosol droplets levitated in an electrodynamic balance (EDB) is presented. The analysis of high resolution elastic Mie resonance spectra allowed the detection of LLPS and further changes in morphology within the aerosol particle. The influence of temperature and size on LLPS are discussed and compared with available literature. Bulk measurements of the refractive index, density and water activity of binary systems (C6/H2O and AS/H2O) and the ternary system (C6/AS/H2O, OIR = 0.5) are reported. From the Mie resonance spectra of these systems, refractive index, density and volume ratio can be retrieved. The obtained thermodynamic data expand the bulk measurements over a wider concentration range and can be used to calculate Mie resonance spectra for different morphologies (core-shell or partially engulfed configurations) and relative humidities. By comparison with the experimental spectra, conclusions can be drawn regarding the morphology of the phase separated aerosol.