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THALOZ Résumé de rapport

Project ID: EVK2-CT-2001-00104
Financé au titre de: FP5-EESD
Pays: United Kingdom

Physico-chemical parameters: rate coefficient for the BrO+HO2 reaction at 298K

The kinetics of the BrO + HO2 reaction have been studied using the technique of flash photolysis / time resolved UV absorption spectroscopy and the rate coefficient for the reaction has been determined, at 298K and 760 Torr O2, as (2.35 +/- 0.82) E-11 / molecule / cm3/ s.

In determining this reaction coefficient, work was also required on the study of the HO2 self-reaction in the presence of methanol, i.e. this result has delivered additional kinetic information, which is of use in subsequent laboratory studies here and elsewhere.

The BrO + HO2 cycle is one of many inter-coupled catalytic ozone destruction cycles and, as such, accurate physico-chemical data are required for reliable modelling of atmospheric ozone.

Increased reliability of physico-chemical data leads to increased reliability of models of atmospheric chemistry. The new data will be implemented in atmospheric chemistry models and it is expected to have an impact upon the accuracy of the modelling of ozone, especially in the stratosphere and in the marine boundary layer. This in turn has implications for the understanding of global change in areas of both atmospheric composition and climate. An accurate understanding of the BrO + HO2 is required in order to calculate the ozone depletion potential of source gases and hence this result may have policy implications in the regulation of source gas emissions.

Reported by

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