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 o xidation reactions, very few experimental studies involving these radicals as reactants have been carried out. Using a fast-flow reactor coupled to ch emical ionization mass spectrometry (CIMS) detection, we have generated and detected the OH-O-2-isoprene peroxy radical. By directly monitoring the pe roxy radical we have obtained an overall rate constant of (7 +/- 3) x 10(-1 3) cm(3) molecule(-1) s(-1) for the reaction of the OH-isoprene adduct with O-2. (C) 2001 Published by Elsevier Science B.V.