Direct investigations of reactions of 2-butoxy radicals using laser pulse initiated oxidation: Reaction with O-2 and unimolecular decomposition at 293 K and 50 mbar

Reactions of 2-butoxy radicals have been investigated using time-resolved m easurements of NO2 and OH concentration profiles in the flash initiated oxi dation of 2-bromobutane and subsequent numerical simulation. 2-butoxy radic als were produced selectively by the excimer-laser photolysis of 2-bromobut ane at 193 or 248 nm followed by the reaction of 2-butyl radicals with Or a nd NO. Whereas NO2 was detected by cw-LIF, detection of OH was achieved by laser long-path absorption at 308 nm. All experiments were performed at 293 K and a total pressure of 50 mbar. The rate coefficients of the O-2 reacti on (k(02)) and of unimolecular decomposition (k(decomp)) have been varied, using the FACSIMILE code, until best fits were obtained. The Following rate coefficients were derived: k(02) = (6.5+/-2)x10(-15) cm(3). molecule(-1). s(-1) and k(decomp) =(3.5+/-2)x10(3) s(-1).