Reaction of carbon atoms, C (2p(2), (3)P) with C(2)H(2), C(2)H(4) and C(6)H(6): Overall rate constant and relative atomic hydrogen production

The multichannel C+C(2)H(2), C(2)H(4) and C(6)H(6) reactions were studied, at room temperature, in a low-pressure fast-flow reactor. Carbon atoms were obtained from the reaction of CBr(4) with potassium atoms. The overall rate constants were found to be (2.4 +/-0.5)x10(-10), (2.1 +/-0.4)x10(-10) and (2.8 +/-0.8)x10(-10) cm(3) molecule(-1) s(-1), respectively. The relative atomic hydrogen productions were determined by resonance fluorescence in the vacuum ultraviolet: H (C+C(2)H(2)/C+C(2)H(4))=0.58 +/-0.04, H (C+C(6)H(6)/C+C(2)H(4))=0.17 +/-0.05, the H production from the C+C(2)H(4) reaction being the reference. The absolute H branching ratio of the C+C(2)H(4) was estimated to be 0.92 +/-0.04.