Atmospheric Chemistry of CH3CHF2(HFC-152a): Kinetics, Mechanisms, and Products of Cl Atom- and OH Radical-Initiated Oxidation in the Presence and Absence of NOx

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Abstract
Smog chamber/Fourier transform infrared (FTIR) and laser-induced fluorescence (LIF) spectroscopic techniques were used to study the atmospheric degradation of CH3CHF2. The kinetics and products of the Cl(2P3/2) (denoted Cl) atom- and the OH radical-initiated oxidation of CH3CHF2 in 700 Torr of air or N2; diluents at 295 ± 2 K were studied using smog chamber/FTIR techniques. Relative rate methods were used to measure k(Cl + CH3CHF2) = (2.37 ± 0.31) × 10-13 and k(OH + CH3CHF2) = (3.08 ± 0.62) × 10-14 cm3 molecule-1 s-1. Reaction with Cl atoms gives CH3CF2 radicals in a yield of 99.2 ± 0.1% and CH2CHF2 radicals in a yield of 0.8 ± 0.1%. Reaction with OH radicals gives CH3CF2 radicals in a yield >75% and CH2CHF2 radicals in a yield 1010 s-1) decomposition to give CH3 radicals and COF2. The remaining approximately 70% become thermalized, CH3CF2O, and undergo decomposition more slowly at a rate of approximately 2 × 103 s-1. At high concentrations (>50 mTorr), NOx is an efficient scavenger for CH3CF2O radicals leading to the formation of CH3COF and FNO.

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