Thesis of Nesrine Shamas

Soutenance de thèse de Nesrine Shamas - laboratoire PC2A

Understanding of atmospheric and indoor air chemistry through HOx radical measurements.

Abstract :

HOx (OH+HO2) and RO2 radicals are involved in oxidation processes in the gas phase, generating secondary products impacting the air quality and human health. Understanding these oxidation processes through the quantification of these radicals is still challenging because of their low concentrations (The UL-FAGE instrument has been improved and used during this work for laboratory measurements (reactivity configuration) to study the oxidation mechanisms of reactions important for indoor and outdoor chemistry involving HOx radicals. During summer 2022, the UL-FAGE participated in an RO2 intercomparison campaign which took place at the SAPHIR chamber (Jülich, Germany). Nine groups using different instruments participated in this campaign. The performance of the UL-FAGE instrument for the OH, HO2 and RO2 measurement under a wide range of atmospherically relevant chemical conditions (e.g. water vapor, nitrogen oxide, various organic compound, day and night chemistry) has been investigated during this campaign. Finally, the UL-FAGE in both quantification and reactivity configuration was deployed to a field campaign (ACROSS) in the Rambouillet forest. The reactivity was measured at two different heights (at the ground and above the canopy) whereas the radical concentrations were measured only at the ground.

Keywords : Atmospheric chemistry,HOx and RO2 radicals,FAGE instrument,field campaigns,simulation chamber,kinetic studies