Reactions in atmospheric particles play important roles in the cycling of organic carbon, nitrogen, and sulfur, e.g., as sources of secondary organic aerosol. Many of these reactions are likely driven by photooxidants such as hydroxyl radical (●OH), singlet molecular oxygen (1O2●) and triplet excited states of organic compounds (3C●). Despite this, there are only a few measurements of hydroxyl radical in illuminated particles and no measurements of singlet oxygen or triplet excited states. To address this gap, we are measuring ●OH, 1O2●, and 3C● in illuminated aqueous extracts of atmospheric particulate matter (PM) from the Central Valley of California collected during winter. Because of wintertime residential wood burning, we expect that the PM is enriched in brown carbon, a precursor for excited triplet states, and phenols, which react rapidly with triplets. The goals of this study are: 1) Make the first measurements of all 3 photooxidants in illuminated particle extracts, 2) compare photooxidant kinetics and concentrations, as well as light absorption, between fog and PM, and 3) explore the relationship between light absorption by PM and 3C● formation. This research will help characterize the oxidant environment of particles, and provide insight into the nature and importance of triplets as an oxidant in the aerosol aqueous phase.

Characterization of photooxidants in atmospheric particles

253rd National Meeting (2017)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.