Reaction of methylidyne CH(X2Π) radical with CH4 and H2S: overall rate constant and absolute atomic hydrogen production Origi

The CH+CH4 and H2S reactions were studied, at room temperature, in a low-pressure fast-flow reactor. CH(X2Π, v=0) radicals were obtained from the reaction of CHBr3 with potassium atoms. The overall rate constants were found at 330 K to be (0.76±0.20)×10−10 and (2.8±0.8)×10−10 cm3 molecule−1 s−1, respectively. The absolute atomic hydrogen productions were determined by resonance fluorescence in the vacuum ultraviolet: H production from the CH+CH4 reaction is 100% and from the CH+H2S reaction is 99+1−4%, the H production from the CH+H2 reaction being the reference. Ab initio studies of the different stationary points relevant to the CH+CH4 reaction have been performed at the CCSD(T)/cc-pVTZ level and comparison is made with experimental results. The experimental results for the CH+H2S reaction is compared with those of a recent theoretical study [Chem. Phys. 242 (1999) 1].