Laboratory studies of heavy ozone

Dissociation of ozone in the Chappuis bands has been used as an O atom source to study isotope effects occurring in the O(3P) + O2(3Σg) recombination reaction. The ozone produced was found to be enriched in both of its heavy isotopes. The pressure dependence (5-1,000 torr) and temperature dependence (127-360 K) of this isotope effect have been investigated. The enrichment is approximately constant from 5 torr to 100 torr and decreases at higher pressures. It increases with temperature, with 50O3 showing a slightly faster rate of increase than 49O3. The results of this experiment have clearly isolated the source of the isotope effect to the gas phase O(3P) + O2(3Σg) recombination reaction. For comparison, the authors also present isotope ratios of ozone formed in an electric discharge. None of the results, however, have shown the large enhancement of 40% or more in mass 50 observed in some stratospheric measurements