[Zurück]

J. Ofner, H.-U. Krüger, C. Zetzsch, H. Grothe:
"HUmic-Like Secondary Organic Aerosol from catechol and guaiacol as model substances for heterogeneous atmospheric chemistry";
Poster: International Conference of Atmospheric Transport and Chemistry in Forest Ecosystems, Castle of Thurnau, Germany; 05.10.2009 - 08.10.2009.

So-called HUmic Like Substances (HULIS) attracted attention in atmospheric aerosol only recently, initiating a discourse about their aromaticity and other properties, such as reactivity and hygroscopicity. A major portion of HULIS originates from volatile organic compounds, which form secondary organic aerosol (SOA) by abiotic oxidizing reactions. Thus aerosol smog-chamber studies with appropriate precursors are needed to generate SOA with HULIS qualities in situ inside the smog-chamber. Catechol and guaiacol were chosen as aromatic precursors for synthetic HULIS production.

The SOA was produced in a 700 L aerosol smog chamber, made of Duran glass and using FEP film as window material. The smog chamber is equipped with a solar simulator (HMI lamp 4.000 W, Osram, and cut-off filter at 300 nm). For each precursor, formation of SOA in the dark with O3 , formation of SOA with simulated sunlight and O3 and formation of SOA and simulated sunlight with O3 and 25% relative humidity was studied using the methods of CNC-DMA, longpath-FTIR and ATR-FTIR absorption spectroscopy. UV/VIS spectroscopy and temperature-programmed-desorption/mass-spectrometry (TPD-MS) will be performed to study certain properties of the so produced HULIS.

Those investigations show that aromatic precursors are able to form synthetic HULIS for laboratory-scale measurements. However, sunlight and relative humidity play a major role in particle production and composition of functional groups, which are the anchor points for heterogeneous atmospheric chemistry.

http://www.bayceer.uni-bayreuth.de/ic_eger/en/top/bayconf/beitrag_detail.php?id_obj=10319