Reaction of O(3P) with Carbon Disulfide: Kinetics and Products

Abstract

The kinetics and products of the reaction of ground-state O atoms with carbon disulfide, of interest for atmospheric and combustion chemistry, were studied using a discharge-flow system combined with modulated molecular beam mass spectrometry. The total reaction rate constant was determined in an absolute way from kinetics of CS2 consumption and reaction product, SO radical formation, and employing a relative rate method with two reference reactions: k1 = (3.35 ± 0.10) × 10–11 exp(−(665 ± 15)/T) cm3 molecule–1 s–1 at T = 220–960 K, with an estimated independent of temperature uncertainty of 15%. The yields of two reaction products, SO and OCS, were determined at T = 220–960 K, resulting in the following expressions for the branching ratio of the corresponding (SO + CS and OCS + S forming) reaction pathways: k1a/k1 = (0.935 ± 0.005) × exp(−(7.4 ± 0.2)/T) and k1b/k1 = (0.067 ± 0.002) × exp(80 ± 8/T), where the uncertainties reflect the statistical 2σ precision. The reaction rate constant and product data from the present work are discussed in comparison with previous experimental and theoretical studies.