Peroxy radicals are known for their role in the tropospheric photochemistry as intermediates in the oxidation of volatile organic compounds leading to the formation of O3 and organic nitrate compounds. Similarly, in the particle phase peroxy radicals, sometimes referred to as Reactive Organic Species (ROS), are also involved in many chemical transformations but are also inducing a consequent fraction of the aerosol health impact. Here, we show that such reactive species are photochemically produced, at the air/water interface, upon irradiation of an organic film made of a simple fatty acids. This production is probed via the heterogeneous chemistry of nitrogen monoxide (NO). The uptake of NO leads to the chemical titration of the interfacial peroxy radicals. Using advanced analytical tools (i.e., PTR-ToF-MS and UHPL-HESI-HR Orbitrap-MS), it was possible to identify the products of this chemical heterogeneous reactions It appears, that this photochemistry, in the actinic region, leads to the formation of a significant amount of ROS and its potential atmospheric significance will discussed. The photochemistry of surfactant at the air/water interface, might have a significant role in the health impact of organic aerosols.

Production of reactive oxygen species at the air: Water interface

2019 Fall National Meeting

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