Kinetics of Active Oxygen Species with Implications for Atmospheric Ozone Chemistry

Photochemical processes involving singlet oxygen (O-2(a(1))), oxygen atoms(,) and ozone are critical in determining atmospheric ozone concentrations. Here we report on kinetic measurements and modeling that examine the importance of the reactions of vibrationally excited ozone. Oxygen atoms and O-2(a(1)) were produced by UV laser photolysis of ozone. Time-resolved absorption spectroscopy was used for O-3 concentration measurements. It was found that vibrationally excited ozone formed by O + O-2 + M O-3() + M recombination reacts effectively with O-2(a(1)) and O atoms. The reaction O-3(upsilon) + O-2(a(1)) O + 2O(2) results in a reduction of the ozone recovery rate due to O atom regeneration, whereas the reaction O-3(upsilon) + O 2O(2) removes two odd oxygen species, resulting in incomplete ozone recovery. The possible impact of these reactions on the atmospheric O-2(a(1)) and O-3 budgets at altitudes in the range of 80-100 km is considered.