Article ID Journal Published Year Pages File Type
4441314 Atmospheric Environment 2009 8 Pages PDF
Abstract

The modification of cloud condensation nucleus (CCN) activity of saturated organic particles resulting from heterogeneous oxidation by OH radicals was studied. Submicron Bis-2-ethylhexyl sebacate (BES) and stearic acid particles were exposed to OH radicals in a reactor flow tube and CCN activity was monitored. The hygroscopicity parameter, κ, for monodisperse stearic acid and BES particles of 145–150 nm in size increased from <0.008 up to 0.08 as a result of OH exposures equivalent to atmospheric exposure timescales of several days to a week. The oxidation of stearic acid particles led to a 50% reduction in particle volume at high OH exposures, indicating an enhanced degree of volatilization of oxidation products compared to oxidized BES particles, along with possible shape/phase change. Surface tension measurements of water extracts of oxidized BES films showed a significant reduction in surface tension due to oxidation. Köhler calculations modeling the CCN measurements suggest that the surface active oxidation products play an important role.

Related Topics
Physical Sciences and Engineering Earth and Planetary Sciences Atmospheric Science
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