Atmospheric chemistry of 1,1,1-trichloroethane: UV absorption spectra and self-reaction kinetics of CCl₃CH₂ and CCl₃CH₂O₂ radicals, kinetics of the reactions of the CCl₃CH₂O₂ radical with NO and NO₂, and the fate of the alkoxy radical CCl₃CH₂O

A pulse radiolysis technique was used to measure the UV absorption spectra of CCl₃CH₂ and CCl₃CH₂O₂ radicals over the range 220-300 nm. At 220 nm, σ(CCl₃CH₂) = (9.4 ± 1.1) × 10^-18 cm² molecule^-1; at 250 nm, σ(CCl₃CH₂O₂) = (2.9 ± 0.3) × 10^-18 cm² molecule^-1. The observed self-reaction rate constants, defined as -d[CCl₃CH₂]/dt = 2k₄[CCl₃CH₂] and -d[CCl₃CH₂O₂]/dt = 2k_5obs[CCl₃CH₂O₂]², were k₄ = (9.1 ± 1.1) × 10^-12 and k_5obs = (4.7 ± 1.6) × 10^-12 cm³ molecule^-1 s^-1. The reaction of CCl₃CH₂O₂ radicals with NO gives CCl₂CH₂O radicals. In the atmosphere, >96% of the CCl₃CH₂O radicals react with O₂ to give CCl₃CHO. The rate constants for the reactions of CCl₃CH₂O₂ radicals with NO and NO₂ were determined to be k₆ ≥ 6.1 × 10^-12 cm³ molecule^-1 s^-1 and k₇ = (6.5 ± 0.4) × 10^-12 cm³ molecule^-1 s^-1, respectively. As a part of this work, the rate constant for the reaction between F atoms and CCl₃CH₃ was determined to be k₃ = (6.8 ± 1.5) × 10^-12 cm³ molecule^-1 s^-1. A relative rate technique was used to measure rate constants for the reactions of Cl atoms with: CCl₃CH₃, (9.9 ± 2.0) × 10^-15; CCl₃CHO, (6.0 ± 1.3) × 10^-12; and CCl₃CH₂OH (3.0 ± 0.6) × 10^-12 (units of cm³ molecule^-1 s^-1) at 296 K. Results are discussed in the context of the atmospheric chemistry of 1,1,1-trichloroethane.