Multi‐isotope study of the O(¹D) + CO₂ exchange and stratospheric consequences

The first multi‐isotope (δ 17 O and δ 18 O) study of an isotopic exchange between an electronically excited species O( 1 D ) and CO 2 has been performed. The O( 1 D ), which was generated from O 3 UV photolysis, undergoes an isotopic exchange with CO 2 via a CO 3 * intermediate transition state. A non‐mass‐dependent isotopic effect is observed via the exchange, which has a direct application to recent stratospheric CO 2 observations and analysis of water presumed to be derived from the Martian surface. The isotopic data are also important in assessing the physical‐chemical properties of the CO 3 * complex.