TEMPERATURE-DEPENDENCE OF THE RATE OF REACTION OF C2H WITH H-2

The rates of reaction of C2H with H-2 and C2H2 have been measured over the temperature range 295-854 K. The C2H radical was produced by exci mer laser photolysis Of C2H2 at 193 nm, and its transient absorption w as monitored throughout the reaction by using a tunable infrared color -center laser. The temperature dependence of the rate constant for the reaction with H-2 exhibited a non-Arrhenius form that could be well r epresented by the following expression: k = (9.44 +/- 0.24) x 10(-14)T 0.9 exp(-1003 +/- 20/T) cm3 molecule-1 s-1. The rate constant for the reaction With C2H2 displayed no definite temperature dependence. It wa s measured as (1.6 +/- 0.3) x 10(-10) cm3 molecule-1 s-1.