FORMATION OF CARBON TRIOXIDE IN PHOTOLYSIS OF OZONE IN LIQUID CARBON DIOXIDE

The 2537-Å photolysis of O3 in liquid CO2 and in liquid SF6 has been investigated at about -45°. In liquid CO2 the quantum yield of O3 disappearance was 0.065 ± 0.05, independent of the O2/O3 ratio. By contrast, the O3 quantum yield in liquid SF6 was much lower and declined with increasing O2/O3 ratios. The results of the photolysis of O3 in CO2 can only be explained in terms of a CO2 mechanism. Relative rate measurements indicate that CO3 is formed in the O(1D)-CO2 reaction at a rate that is comparable to the reaction rate of O(1D) with propane and isobutane. CO3 reacts with neither O3 nor O2 but apparently disappears by the reaction CO3 + CO3 → 2CO2 + O2.