Carbonyl compounds, namely aldehydes and ketones, are significant participants in atmospheric processes such as the formation of tropospheric ozone and photochemical smog, and account for much of the chemical reactivity of secondary organic aerosols (SOA). They are also known to readily photodegrade in the presence of solar radiation to give rise to secondary products. Though the gas-phase photochemistry of these atmospherically relevant carbonyl compounds has been extensively studied, the condensed-phase photolysis of these carbonyl compounds in water and in particulate matter is poorly understood. In this study, 1,2-cyclohexanedione was selected to model the gas, liquid, and solid-phase photolysis of atmospherically relevant carbonyl compounds using broadband 300-400 nm and 254 nm UV radiation. Solutions of this diketone were prepared in various organic solvents, photolyzed in the gas, liquid, or solid-state using custom set-ups, then analyzed by PTR-MS, HPLC, GCMS, and/or LCMS. The extinction coefficient of 1,2-cyclohexanedione was also experimentally derived using UV-Vis spectroscopy. The purpose of this study is to assess the effects of physical phase and environmental conditions on the photochemistry of atmospherically relevant carbonyl compounds by comparing the secondary products formed in the gas, liquid, and solid-state photolysis.

Photolysis of atmospherically relevant carbonyl compounds in different phases

251st National Meeting (2016)

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