Aromatic Hydrocarbon Research in the European Photoreactor (EUPHORE)

Aromatic hydrocarbons are rated amongst the most important classes of compounds with regard to the formation of photo-oxidants in the lower atmosphere. A recent theoretical study [1] using a trajectory model approach estimated the aromatic hydrocarbons to be responsible for about 40 % of the anthropogenic ozone formation in north-western Europe, their contribution to the total nonmethane hydrocarbon emissions was calculated to be 26 %. Despite their importance, the degradation mechanisms of aromatic hydrocarbons, which determine photo-oxidant formation, are still uncertain. This is mainly due to their far greater complexity compared to those of other compound classes like alkanes or alkenes. This complexity and the problems associated with it will be described in more detail below, when different aspects of aromatic hydrocarbon photochemistry that have been studied in the EUPHORE photochemical reaction chamber are highlighted.