Temperature dependence of the limiting low- and high-pressure rate constants for the CH3O+NO2+He reaction over the 250-390 K temperature range

The laser photolysis laser-induced fluorescence technique was used to measu re the pressure (p(T) = 50-600 Torr) and temperature (T = 250-390 K) depend ence of the rate constant for the CH3O + NO2 reaction in He. CH3ONO/(NO2He) -He-/ mixtures were photolysed at 248 nm and the CH3O radical generated was monitored by LIF emission. Combined with previously reported rate coeffici ents at low pressures and after subtracting the disproportionation contribu tion to this reaction, our corrected kinetic experimental data, k(1a)(T), w ere fitted to the Troe expression, yielding the limiting low- (k(1a)(0)) an d high-pressure (k(1a)(infinity)) rate constants. The temperature dependenc e found was (k(1a)(0) +/- 2 sigma) = (3.93 +/- 0.05) x 10(-29)(T/300)(-(1.7 4 +/- 0.40)) cm(6) molecule(-2) s(-1) and (k(1a)(infinity) +/- 2 sigma) = ( 2.40 +/- 0.02) x 10(-11) (T/300)(-(0.88 +/- 0.32)) cm(3) molecule(-1) s(-1) . These results are compared with those previously reported at room tempera ture. (C) 2000 Elsevier Science B.V. All rights reserved.