Time-resolved kinetic studies on quenching of CH(A 2Δ and B 2Σ−) by (CX3)2CO, CF3COOX, and CXCl3 (X=H or D) and alkane molecules

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Abstract
The quenching rate constants kq of CH(A 2Δ and B 2Σ−) radicals by (CX3)2CO, CF3COOX, and CXCl3 (X=H or D), and some alkane molecules have been measured using laser photolysis of CHBr3 at 266 nm to produce CH radicals and time‐resolved fluorescence quenching measurements. An isotope effect is found on quenching of both A and B states by deuterated and hydride molecules and the quenching rate constants of both A and B states increase steadily with increase of the number of C–H bonds contained in the alkane molecules. The formation cross sections of complexes of electronically excited CH radicals and alkane molecules were calculated by means of a collision complex model. It is shown that the dependence of the formation cross section of complex on the number of C–H bonds contained in alkane molecules is in agreement with that of the measured quenching cross section.