Kinetics of CH2Br and CH2BrO2 radicals in reactions with NO and O2

PHYS 20

Anatoly V Komissarov, Anatoly.Komissarov@jpl.nasa.gov, Chemical Kinetics and Photochemistry Group, Jet propulsion Laboratory/California Institute of Technology, 4800 Oak Grove Dr, M/S 183-901, Pasadena, CA 91109, Stanley P. Sander, ssander@jpl.nasa.gov, Earth and Space Sciences Division, Jet Propulsion Laboratory, California Institute of Technology, M/S 183-901, 4800 Oak Grove Drive, Pasadena, CA 91109, and Randall R. Friedl, randall.r.friedl@jpl.nasa.gov, Jet Propulsion Laboratory, 4800 Oak Grove Dr, Pasadena, CA 91109.

The formation of secondary bromine atoms has been observed in the 266 nm photolysis of CH2Br2 in the presence of O2 and NO. By following the rate of growth of this secondary Br atom signal as a function of conditions, rate constants have been determined for the reactions CH2Br + O2, CH2Br + NO (both pressure-dependent),  and CH2BrO2 + NO  (1.84±0.07) × 10-11 cm3molecule-1s-1 at 23°C). The following estimates of the low and high pressure limits for recombination of CH2Br with O2 and NO were obtained:

CH2Br + O2 + M(N2) → CH2BrO2 + M          k0=(3.1±1.5)*10-30  cm6molecule-2s-1 

                                                                 kinf=(2.4±0.2)*10-12 cm3molecule-1s-1

CH2Br+NO+M(N2) → CH2BrNO + M             k0=(4.5±1.2)*10-29 cm6molecule-2s-1

                                                                 kinf=(3.9±0.7)*10-12 cm3molecule-1s-1

The results of this study will be discussed in the context of our previous work on the oxidation mechanism of CHBr3, and the implications for oxidation of organobromine compounds in the terrestrial lower troposphere.

 

Physical Chemistry of Atmospheric Processes
8:00 AM-12:00 PM, Sunday, April 6, 2008 Morial Convention Center -- Rm. 343, Oral

Division of Physical Chemistry

The 235th ACS National Meeting, New Orleans, LA, April 6-10, 2008