Absolute rate of the reaction of bromine atoms with ozone from 200 to 360 K

摘要

The rate constant for the reaction Br+O3rarr;BrO+O2has been measured from 200 to 360 K by the technique of flash photolysis coupled to time resolved detection of bromine atoms by resonance fluorescence (FPndash;RF). Br atoms were produced by the flash photolysis of CH3Br at lgr;gsim;165 nm. lsqb;03rsqb; was monitored continuously under reaction conditions by absorption at 253.7 nm. At each of five temperatures the results were independent of substantial variations in lsqb;O3rsqb;, total pressure (Ar), and limited variations in flash intensity (i.e., initial lsqb;Brrsqb;). The measured rate constants obey the Arrhenius expression,k= (7.74plusmn;0.50) times;10minus;12exp(minus;603plusmn;16/T) cm3moleculeminus;1sminus;1, where the error quoted is two standard deviations. The results are compared with previous determinations which have employed the discharge flowndash;mass spectrometric technique.