This project will investigate the mass-independent fractionation (MIF) effect that leads to enrichment of stratospheric ozone in heavy isotopes of oxygen (17O and 18O). The theory for treating this ozone forming reaction will be further developed using a mixed quantum/classical method to characterize the collisional energy transfer without using reduced-dimension approximations. The use of several atmospheric bath gases will be studied as quenchers for the reaction. The MIF of oxygen in the ozone-forming reaction has been shown to disappear when a very efficient molecular quencher, such as SF6, is used. The emphasis of the project will be on moving from the analytic model to a master-equation treatment of the kinetics. The project will also include the first-ever quantum dynamic calculations for the formation of ozone on surfaces.
The mass-independent fractionation (MIF) of O3 has a significant impact on our understanding of the ozone's chemistry, production, lifetime and loss in the atmosphere, and the effect ozone has on global climate change. The advances made in further elucidating the MIF of O3 will provide the key to understanding the MIF for several other molecules, such as stratospheric CO2, N2O and CO. The isotopic composition of atmospheric CO2 is often used to identify its sources and further characterization of the MIF of CO2 will lead to an increased understanding of the global carbon budget.
