KINETICS OF THE ADDITION-REACTION OF METHYL RADICALS WITH NITRIC-OXIDE STUDIED BY PULSE-RADIOLYSIS COMBINED WITH INFRARED DIODE-LASER SPECTROSCOPY

The reaction CH3 + NO (+ M) --> CH3NO ( + M) was initiated by pulse radiolysis of acetone/nitric oxide mixtures and the kinetics of methyl radicals was studied by time-resolved infrared absorption spectroscopy. The rate constant was found to be strongly pressure dependent in the range of p (M) = 6.5-150 mbar at 298 K with M = acetone as the third body. The experimental results are represented in terms of a fall-off curve centered at 37 mbar with limiting high- and low-pressure rate constants of k(rec,infinity) = (6.6 +/- 0.9) x 10(9) x (T/300)0.6 M-1 s-1 and k(rec,0)/[M] = (4.4 +/- 0.4) x 10(12) x (T/300)-3.5 M-2 s-1, respectively.