Low‐pressure rate coefficients of the reaction of O( 3 P) with CF 3 I and CH 3 I

Absolute rate coefficients for the gas‐phase reactions of CF 3 I and CH 3 I with O( 3 P) atoms were measured at 298 K by the discharge flow technique coupled to resonance fluorescence to monitor O( 3 P) atoms. This is the first kinetic study for these reactions under low‐pressure conditions (1.56–3.26 Torr). The overall rate coefficients were (5.2 ± 0.7) × 10 −12 and (2.3 ± 0.3) × 10 −11  cm 3  molecule −1  s −1 , respectively. The experiments were carried out under pseudo‐first‐order conditions with [O( 3 P)] 0  ≪ [RI] 0 . The results are compared with previous measurements using different experimental techniques at higher pressures. Free energy relationships and atmospheric implications are discussed. Copyright © 2008 John Wiley & Sons, Ltd.