Reaction of carbon atoms, C (2p2, 3P) with C2H2, C2H4 and C6H6: Overall rate constant and relative atomic hydrogen production

Abstract

The multichannel C + C₂H₂, C₂H₄ and C₆H₆ reactions were studied, at room temperature, in a low-pressure fast-flow reactor. Carbon atoms were obtained from the reaction of CBr₄ with potassium atoms. The overall rate constants were found to be (2.4 ± 0.5) × 10⁻¹⁰, (2.1 ± 0.4) × 10⁻¹⁰ and (2.8 ± 0.8) × 10⁻¹⁰ cm³ molecule⁻¹ s⁻¹, respectively. The relative atomic hydrogen productions were determined by resonance fluorescence in the vacuum ultraviolet: H (C + C₂H₂/C + C₂H₄) = 0.58 ± 0.04, H (C + C₆H₆/C + C₂H₄) = 0.17 ± 0.05, the H production from the C + C₂H₄ reaction being the reference. The absolute H branching ratio of the C + C₂H₄ was estimated to be 0.92 ± 0.04.