photoSENSitized reactions : a new OXidant pathway in the atmosphere – SENSOX

A better understanding of chemical processes is necessary to evaluate their impact to the atmospheric composition changes and more generally to the air quality and climate. Between the different transformations processes, oxidation pathway represents one of the most important in atmospheric condensed phase. Despite a well-documented quantification and reactivity assessment of hydroxyl radical, photosensitized reactions have been suggested to induce relevant and up to now not considered, oxidation in the tropospheric condensed phase through lab scale experiments. Photosensitized reactions are initiated by excited triplet states (3T*) generated through absorption of solar radiation by chromophoric organic matter, naturally present in tropospheric condensed phases (particles and droplets). Recently, few research groups reported the formation of 3T* in atmospheric condensed phase and suggested their role for the sink of organic compounds.
In this context, our project wants to answer the following questions: do particles or droplets (fog/cloud) in contrasting environments and seasons exhibit photosensitizing properties? Can such photosensitized induce significant reactivity representing a new oxidation pathway in the troposphere? How important is this chemistry in the frame of cloud multiphase reactivity? To address the issues, we built SENSOX project with four research groups having a recognized expertise in the field of atmospheric monitoring, chemistry, photochemistry and multiphase modelling.