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Accueil du site > Thèmes de recherche > Atmosphère & environnement > 2.1. Dégradation des Composés Organiques Volatils et semi-volatils et formation d’aérosols secondaires > 2.1.3 Secondary organic aerosols (SOA) formation

2.1.3 Secondary organic aerosols (SOA) formation

The gas phase ozonolysis of a series of unsaturated biogenic or anthropogenic organic compounds (such as myrcene, linalool, ocimene, α-farnesene, unsaturated alcohols, unsaturated ethers…) has been investigated. The reaction rate coefficients have been determined which enabled to calculate the tropospheric lifetimes of these species. Most of the studied compounds have been found to be very short lived towards the reaction with ozone (less than 2 hours). The SOA formation yields were found to be in the range 1-30 % under atmospheric conditions. Nucleation thresholds have been determined for some of the reactions studied and aerosol formation mechanisms involving the Criege biradical intermediates have been suggested for some species. The chemical composition analysis of the SOA formed showed a significant amount of organic acids. These compounds are also very reactive towards hydroxyl and nitrate radicals. This high reactivity implies that large emissions of these species will play a significant role in the atmospheric boundary layer in terms of photooxydant and organic secondary aerosol formation. (e.g. ACL76, 77, 89, 93, 95, 97). These studies have been carried out within the LEFE (CNRS-INSU) and Primequal programme and the Eurochamp 1 and 2 projects (FP6 and 7).