Recent work has indicated that organic aerosol growth through photosensitized VOC oxidation may be a significant contributor to ambient aerosol mass. Most studies have focused on imidazole photosensitization under dry conditions (RH ≤ 15%), and have worked to characterize the photosensitized oxidation of limonene by imidazole-2-carboxaldehyde (IC). IC is formed from the aqueous reaction of glyoxal and ammonia and has been shown to be a contributor to brown carbon. The conditions under which this photosensitized growth occurs have not been fully explored, and we must understand them in order to predict the importance of this aerosol growth pathway. We present experiments probing photosensitized aerosol growth under a variety of conditions. The magnitude of observed photosensitized growth varies as a function of ambient relative humidity, particle pH, photosensitizer concentration, and VOC concentration. This work indicates that the extent of photosensitized growth may be highly dependent on regional atmospheric conditions, and that the chemical form of the photosensitizer may play a significant role in its ability to initiate VOC oxidation.

Exploration of the role of ambient conditions in organic aerosol growth via photosensitized oxidation of VOCs

253rd National Meeting (2017)

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