Photochemical Processing of Filter Collected α-pinene SOA; Molecular Composition Changes and Absorption Properties

Absorption of solar radiation by secondary organic aerosol (SOA) in the atmosphere causes loss of organic particulate matter. However, the kinetics of this mass loss and the effects on the average molecular composition and optical properties are not well known. Improved understanding of these processes is necessary to help constrain atmospheric SOA mass loadings. Here, we expose α-pinene SOA collected on filters to UV-VIS radiation from a xenon arc lamp to simulate photolytic processing of SOA particulate matter. Changes in the molecular composition and absorption properties of the organic mixture are measured at discrete time points using ultra-high resolution mass spectrometry and UV-VIS spectroscopy. We compare differences in these properties to changes reported in the literature for aqueous SOA processing.