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H. Grothe:
"The Surface Chemistry of Soot and its Impact on Atmospheric Processes";
Vortrag: Seminar of the school of industrial engineering, Universidad de Castilla-La Mancha, Toledo, Spain (eingeladen); 31.10.2017.

Soot particles are ubiquitous in the Earth´s troposphere and are defined as solid primary, carbonaceous products from an incomplete combustion process of natural or anthropogenic origin. It is reported that graphite-like carbon particles could catalyze the phase transition from liquid water into ice crystals even though they are naturally hydrophobic. Soot may become partially hydrated by oxidation or by deposition of water- soluble species present in air, such as sulphuric acid and nitric acid and therefore may increase the ice nucleation activity (INA). Current laboratory studies of the INA of soot gave contradictory results indicating that soot particles might be too complicated to be adequately described in its full complexity regarding heterogeneous ice nucleation. An adequate parameterization of particles´ surface properties as well as the time dependence of the ice nucleation process is still under discussion. Graphene and their modifications offer due to their characteristics simplified model systems. Theoretical calculations of graphene revealed the impact of e.g. hydrophobicity and crystallinity on the INA. In this work we are presenting investigations of the INA of different types of graphene and graphene oxides as well as of chemically treated soot particles. Immersion drop freezing experiments as well as comprehensive analytic analyses like X-ray photoelectron-, Raman spectroscopy [1] and transmission electron microscopy were performed.

[1] A. Sadezky, H. Muckenhuber, H. Grothe, R. Niessner, U. Pöschl, Carbon 43 (2005) 1731.

http://publik.tuwien.ac.at/files/publik_265659.pdf