Reactions of chlorine oxide radicals. Part 5.—The reaction 2ClO (X2Π)→ products

Abstract

Ground state ClO, X²Π, ν″= 0, free radicals, generated at 298 K in a discharge-flow system, are removed in kinetically second order reactions (1), ClO + ClO[graphic omitted] all products. (1) The overall rate constant k₁(at 298 K) has been determined mass spectrometrically using molecular beam sampling: k₁=(2.2₅± 0.3₀)× 10^–14 cm³ molecule^–1 s^–1. Absolute ClO radical concentrations were determined by conversion of ClO into NO₂ via the reaction, NO + ClO → NO₂+ Cl.

The mechanism of reaction (1) is considered in detail. Studies using atomic resonance spectrometry have confirmed that formation of Cl atoms, reaction (1b), is a major reaction channel in the second order decay of ClO: ClO + ClO [graphic omitted] Cl + ClOO; (1b) reaction (1a) has also been identified, ClO + ClO [graphic omitted] Cl + OClO; (1a) however, this reaction channel for removal of ClO, although important at elevated (flame) temperatures, represents only about 5 % of the total reaction (1), of ClO + ClO, at 298 K.