Multi‐isotope study of ozone: Implications for the heavy ozone anomaly

Abstract

Laboratory experiments have been performed with O and O 2 in their ground electronic states to study the distribution of all possible ozone isotopes formed. Results show that with respect to 48 O 3 the two symmetric molecules 17 O 17 O 17 O and 18 O 18 O 18 O are depleted, in good agreement with standard recombination theory. A large enrichment of about 18% is found in the asymmetric molecule 16 O 17 O 18 O, while all others carry about 2/3 of that. A comparison with past laboratory and stratospheric ozone isotope measurements leads to the following conclusion: There is a standard enrichment which resides in asymmetric molecules only. It will lead to an enrichment of stratospheric 49 O 3 and 50 O 3 of 8 to 9%; this has been actually observed in recent balloon experiments. Occasionally, the enrichments in the stratosphere are larger, reaching 40% at certain altitudes. Only when ozone was formed in an electric discharge process have larger enrichments been measured in laboratory experiments, affecting both symmetric and asymmetric molecules. The results provide an important connection between numerous laboratory studies and stratospheric measurements.