Evidence for formation of OH radicals from the reaction of O₃ with alkenes in the gas phase

Abstract

A series of experiments investigating the formation of OH radicals from O 3 ‐alkene reactions are described. Pairs of OH tracer compounds—aromatic and aliphatic hydrocarbons—were added to O 3 ‐alkene mixtures in small quantities. Under these conditions, a large fraction of the tracer is consumed, resulting in a much larger signal than in experiments using excess tracer. The average decay ratios of tracer pairs in 30 experiments were within 7% of those predicted by literature rate constants for tracer‐OH reactions, strongly supporting the hypothesis that OH is formed directly from O 3 reaction with alkenes.