OH/OD initiated oxidation of isoprene in the presence of O-2 and NO
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The kinetics of the isoprene-OH/OD reaction in the presence of O 2: and NO have been studied using laser photolysis/laser-induced fluorescence. We report pressure and temperature-dependent rate constants for the addition of OH/OD to isoprene are in good agreement with previous studies. On the basis of simulations to OH cycling curves, we find a value of (9.0 3.0) 10-12 molecule-1 cm3 s-1 for the overall reaction rate constant of hydroxy peroxy radical with NO at 298 K. We report a rate constant for O2 addition to the hydroxy alkyl radical of (2.3 2.0) 10-12 molecule-1 cm3 s-1 at 298 K. We find little generation of OH from the OD initiated oxidation of isoprene, and no significant differences in OH and OD cycling, suggesting that H-shift isomerization is the major pathway for -hydroxy alkoxy radicals, in agreement with theoretical predictions.