Experimental study of hydroxyalkyl peroxy radicals from OH-initiated reactions of isoprene

Despite the importance of hydroxy–isoprene peroxy radicals in cycling of NO to NO2, in partitioning of the final products, and in propagation of the oxidation reactions, very few experimental studies involving these radicals as reactants have been carried out. Using a fast-flow reactor coupled to chemical ionization mass spectrometry (CIMS) detection, we have generated and detected the OH–O2–isoprene peroxy radical. By directly monitoring the peroxy radical we have obtained an overall rate constant of (7±3)×10−13 cm3 molecule−1 s−1 for the reaction of the OH–isoprene adduct with O2.