A gas-phase crossed-beam study of OH produced in the radical–radical reaction of O(3P) with iso-propyl radical (CH3)2CH

Abstract

The gas-phase radical–radical reaction dynamics of ground-state atomic oxygen [O(³P)] with iso-propyl radicals, (CH₃)₂CH, were investigated by applying a combination of high-resolution laser-induced fluorescence spectroscopy in a crossed-beam configuration and ab initio calculations. The nascent distributions of OH (X²Π: υ′′ = 0) from the major reaction channel O(³P) + (CH₃)₂CH → C₃H₆ (propene) + OH showed substantial internal excitations with a bimodal feature of low- and high-N′′ components with neither spin–orbit nor Λ-doublet propensities. Unlike previous kinetic results, proposed to proceed only through the direct H-atom abstraction process, on the basis of the population analysis and comparison with the statistical theory, the title reaction can be described in terms of two competing mechanisms at the molecular level: direct abstraction process and indirect short-lived addition-complex-forming process with a ratio of 1.25 : 1.