Rate Constants for the Gas-Phase Reactions of Ozone with Isoprene, α- and β-Pinene, and Limonene as a Function of Temperature

The rate constants for the gas-phase reactions of ozone with the biogenic hydrocarbons isoprene, α- and β-pinene, and limonene were measured using the relative rate technique over the temperature range 242−363 K and at 760 Torr total pressure. Helium was the diluent gas, and the reactants were detected by on-line mass spectrometry. The following Arrhenius expressions have been determined for these reactions (in units of cm 3 molecule -1 s -1 ): isoprene, ( ) × 10 -15 exp[−(1998 ± 63)/ T ]; α-pinene, ( ) × 10 -15 exp[−(530 ± 150)/ T ]; β-pinene, ( ) × 10 -15 exp[−(1297 ± 75)/ T ]; and limonene, ( ) × 10 -15 exp[−(783 ± 72)/ T ]. The Arrhenius parameters determined here for the reactions of ozone with β-pinene and limonene are the first to be reported.