TEMPERATURE AND PRESSURE-DEPENDENCE OF THE NCO+C2H2 REACTION

The reaction of NCO(X (2) Pi) radicals with C2H2 was investigated under pseudo-first-order conditions at 20 and 100 Ton total pressure as a function of temperature in the range 298-981 K. NCO radicals were generated by excimer laser photolysis of QNCO/Ar mixtures and were detected by laser-induced fluorescence. In the temperature range 296-597 K the measured rate constants exhibit a positive temperature dependence which is described by the Arrhenius equation k(NCO+C2H2)(T) = (2.4 +/- 0.1) x 10(-12) exp[-(7.6 +/- 0.2)/RT] cm(3) s(-1), with E(A) in units of kT/mol. In addition, the rate constant of the reaction NCO + C2H2 was found to be pressure independent in the range 10-560 Ton at 298 K within experimental error.