Reaction kinetics involving ground X2Π and excited A2Σ+ hydroxyl radicals. Part 1.—Quenching kinetics of OH A2Σ+ and rate constants for reactions of OH X2Π with CH3CCl3 and CO

Abstract

Resonance fluorescence has been used to determine the rate constants k₁ and k₂(cm³ molecule^–1 s^–1)(1 σ) of elementary reactions of ground state OH X²Π radicals from 293 to 430 K: OH + CH₃CCl₃[graphic omitted]CH₂CCl₃+ H₂O (1), log₁₀k₁=(–11.62 ± 0.14)–(1394 ± 113)/2.303 T; OH + CO [graphic omitted] CO₂+ H (2), k₂=(–12.66 ± 0.12)–(88 ± 40)/2.303 T.

In addition, steady-state measurements of resonance fluorescence have been used to determine the rate constants at 293 K for electronic (or reactive) quenching of excited OH A²Σ⁺ radicals with a variety of halogenocarbon molecules. Most of these excited-state quenching reactions occur with collision efficiencies approaching unity at 293 K, unlike the corresponding reactions involving ground state OH radicals.