| Abstract: |
In building environments, oxidation reactions involving ozone and terpenoids lead to nano-sized particle formation [Jang et al. 1999]. Low volatility products of these reactions are important and add to particle mass concentrations in air through nucleation or condensation onto existing suspended particles [Lamorena and Lee 2008]. Several recent studies have focused on ozonolysis of monoterpenes (e.g. pinene, limonene, and terpineol) and shown that these reactions are major sources of indoor secondary organic aerosols (SOAs). Because of instrument limitations, there had been little information regarding freshly nucleated particles with diameters less than 10 nm until recently. Also, for secondary organic aerosols (SOAs), i.e., particles formed from gas-phase chemistry, information regarding the evolution of particle size distributions is lacking. To better understand the underlying processes of SOA formation, it is essential to evaluate particle nucleation (in terms of size and mode) and the associated evolution rate. In this study, a series of experiments were conducted in both chambers and a residential room to characterize freshly nucleated particles (dp = 3nm to 100 nm) generated from the gas-phase reaction of d-limonene and ozone. Influences of water vapor, reactant concentration, and OH-scavenger on ozone degradation of limonene and its particle formation were investigated. |
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