Kinetics of the reaction of HO2with ozone

摘要

Rate constants were measured for the reaction HO2+O3rarr;OH+2O2(k1) using a dischargehyphen;flow system with laser magnetic resonance detection of both HO2and OH.k1was determined directly from the first order decay of HO2in excess O3when C2F3Cl was added to scavenge the OH product and prevent interference from the faster reaction OH+O3rarr;HO2+O2(k2). The ratiok2/k1was independently determined from the steadyhyphen;state lsqb;HO2rsqb;/lsqb;OHrsqb; ratio obtained without C2F3Cl. Results from the scavenger method are given byk1= (1.4plusmn;0.4)times;10minus;14exp lsqb;minus;(580plusmn;100)/Trsqb; cm3thinsp;sminus;1for 245 KT365K. Results of the ratio measurements are in good agreement with these data when combined with a directly measured value ofk2quest;1.0)times;10minus;14cm3thinsp;sminus;1at 300 K. These measurements are compared with other studies and some implications for stratospheric ozone chemistry are discussed.