Isoprene peroxy radical dynamics: constraints from laboratory studies

Abstract:

We report experimental measurements of the oxidation products of isoprene in the laboratory using gas chromatography coupled to CF₃O^- chemical ionization mass spectrometry. This technique provides a wealth of new data on the isomer distributions of nitrates and hydroperoxides formed from the oxidation of isoprene. The isomer distributions and stable product yields provide key constraints on the rates of interconversion and isomerization of isoprene peroxy radicals. We show that the isomer distribution of products formed at short peroxy radical lifetimes often found in laboratory studies differ from the isomer distribution formed at longer, atmospherically relevant peroxy radical lifetimes. The implications for atmospheric chemistry models and global oxidant budgets will also be discussed.