<> "The repository administrator has not yet configured an RDF license."^^ . <> . . "Study of phase transitions in atmospheric aerosols: freezing and efflorescence of complex aqueous mixtures"^^ . "This work addresses homogeneous and heterogeneous nucleation phenomena in atmospheric aerosol particles. First, the heterogeneous freezing of supercooled droplets containing feldspar particles has been investigated in a novel droplet freezing assay instrument. Second, the efflorescence of NaCl-dihydrate in supercooled NaCl and sea salt solute droplets has been studied with a technique combining electrodynamic balance (EDB) and Raman microscopy. The study was aimed to clarify the fundamental stochastic nature of homogeneous and heterogeneous nucleation in metastable aerosol systems.\r\nThe ice nucleation efficiency of feldspar particles has been measured by depositing several hundred suspension droplets onto continuously cooled silicon substrate. Three types of experiments have been conducted: cooling ramp, isothermal freezing at constant temperature and freeze-thaw cycles. The observed freezing behavior have been interpreted in a framework of classical nucleation theory (Soccer Ball Model, SBM). The SBM was shown to adequately describe the shift of the freezing curves towards lower temperature with dilution, the cooling rate dependence and the ice nucleating active sites (INAS) surface density n_s (T) in a wide temperature range. Moreover, the SBM was capable of reproducing the variation of INAS surface density n_s (T) with concentration of IN in the suspension droplets and correctly predicting the leveling-off of the n_s (T) at low temperature. The freeze-thaw experiments have clearly shown that the heterogeneous freezing induced even by very active ice nucleating species still possesses a stochastic nature, with the degree of randomness increasing towards homogeneous nucleation. The reliability of the experimental approach has been also demonstrated during the Fifth Ice Nucleating intercomparison campaign (FIN02).\r\nSingle solution droplets consisting of pure NaCl or simulated sea salt were suspended into the EDB maintained at constant temperature and relative humidity. A statistical analysis of several hundreds of individual efflorescence events allowed to describe the probability of NaCl dihydrate crystallization as a function of temperature, droplet volume, and solute concentration, and to derive the homogeneous and heterogeneous nucleation rate coefficients of NaCl dihydrate. Based on these measurements, the discrepancies between temperature dependent efflorescence of NaCl dihydrate observed in the previous experiments could be quantitatively explained for the first time. Furthermore, the experiments with the sea salt solution droplets showed an enhanced formation of NaCl dihydrate due to the faster crystallization of secondary sea salt components triggering the heterogeneous nucleation of NaCl dihydrate."^^ . "2016" . . . . . . . "Andreas"^^ . "Peckhaus"^^ . "Andreas Peckhaus"^^ . . . . . . "Study of phase transitions in atmospheric aerosols: freezing and efflorescence of complex aqueous mixtures (PDF)"^^ . . . "Doktorarbeit_Peckhaus.pdf"^^ . . . "Study of phase transitions in atmospheric aerosols: freezing and efflorescence of complex aqueous mixtures (Other)"^^ . . . . . . "indexcodes.txt"^^ . . . "Study of phase transitions in atmospheric aerosols: freezing and efflorescence of complex aqueous mixtures (Other)"^^ . . . . . . "lightbox.jpg"^^ . . . "Study of phase transitions in atmospheric aerosols: freezing and efflorescence of complex aqueous mixtures (Other)"^^ . . . . . . "preview.jpg"^^ . . . "Study of phase transitions in atmospheric aerosols: freezing and efflorescence of complex aqueous mixtures (Other)"^^ . . . . . . "medium.jpg"^^ . . . "Study of phase transitions in atmospheric aerosols: freezing and efflorescence of complex aqueous mixtures (Other)"^^ . . . . . . "small.jpg"^^ . . "HTML Summary of #21653 \n\nStudy of phase transitions in atmospheric aerosols: freezing and efflorescence of complex aqueous mixtures\n\n" . "text/html" . . . "500 Naturwissenschaften und Mathematik"@de . "500 Natural sciences and mathematics"@en . .