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Faraday Discuss

Title:		Organic aerosol formation photo-enhanced by the formation of secondary photosensitizers in aerosols
Author(s):		Aregahegn KZ; Noziere B; George C;
Address:		"Universite de Lyon, universite Lyon 1, CNRS, UMR5256, IRCELYON, Institut de recherches sur la catalyse et l'environnement de Lyon, Villeurbanne F-69626, France"
Journal Title:		Faraday Discuss
Year:		2013
Volume:		165
Issue:
Page Number:		123 - 134
DOI:		10.1039/c3fd00044c
ISSN/ISBN:		1359-6640 (Print) 1359-6640 (Linking)
Abstract:		"Secondary organic aerosols (SOA), which are produced by the transformations of volatile organic compounds in the atmosphere, play a central role in air quality, public health, visibility and climate, but their formation and aging remain poorly characterized. This study evidences a new mechanism for SOA formation based on photosensitized particulate-phase chemistry. Experiments were performed with a horizontal aerosol flow reactor where the diameter growth of the particles was determined as a function of various parameters. In the absence of gas-phase oxidant, experiments in which ammonium sulfate seeds containing glyoxal were exposed to gas-phase limonene and UV light exhibited a photo-induced SOA growth. Further experiments showed that this growth was due to traces of imidazole-2-carboxaldehyde (IC) in the seeds, a condensation product of glyoxal acting as an efficient photosensitizer. Over a 19 min irradiation time, 50 nm seed particles containing this compound were observed to grow between 3.5 and 30 +/- 3% in the presence of either limonene, isoprene, alpha-pinene, beta-pinene, or toluene in concentrations between 1.8 and 352 ppmv. The other condensation products of glyoxal, imidazole (IM) and 2,2-bi1H-imidazole (BI), also acted as photosensitizer but with much less efficiency under the same conditions. In the atmosphere, glyoxal and potentially other gas precursors would thus produce efficient photosensitizers in aerosol and autophotocatalyze SOA growth"
Keywords:
Notes:		"PubMed-not-MEDLINEAregahegn, Kifle Z Noziere, Barbara George, Christian eng England 2013/01/01 Faraday Discuss. 2013; 165:123-34. doi: 10.1039/c3fd00044c"