München 2004 – wissenschaftliches Programm
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UP: Umweltphysik
UP 21: Aerosol und Messtechnik
UP 21.9: Fachvortrag
Dienstag, 23. März 2004, 18:30–18:45, HS 221
Homogeneous Nucleation of Supersaturated Droplets of NaCl and Sea Salt Aerosols — •M. Hamza1,2, W. Roether3, M. Lechner4, and E. Rühl1 — 1Institut für Physikalische Chemie, Universität Würzburg, Am Hubland, 97074 Würzburg — 2Fachbereich Physik, Universität Osnabrück — 3Institut für Umweltphysik, Universität Bremen — 4Institut für Chemie, Universität Osnabrück
Homogeneous nucleation of aqueous sodium chloride (NaCl) solutions and natural sea salt aerosol droplets is investigated using single, trapped particles in an electrodynamic balance. The phase transition liquid-to-solid is investigated as a function of temperature and humidity, where the experimental conditions favor homogeneous nucleation. The enthalpy of supersaturated NaCl- and solution droplets from the Mediterranean Sea are derived as well as the rates of homogeneous nucleation. The results indicate that the phase transition liquid-to-solid is related to the salinity of seawater and the depth, where the samples were collected. It is assumed that organic substances affect homogeneous nucleation of the sea salt droplets. Therefore, we have investigated model solution droplets containing NaCl, where organic substances were added. These are either bound in the bulk or on the surface of the droplets. It is observed that specific changes in homogeneous nucleation occur, if the amount of organic species is varied.