Sierra Dabby L&S Math & Physical Sciences
Anomalous Oxygen-Mass Independent Fractionation in Ozone Formation
Ozone formation is accompanied by anomalous oxygen isotope effects. Oxygen has three stable isotopes: 16O, 17O, and 18O (relative abundances of 99.76%, 0.04% and 0.20% with 17O and 18O discovered at Berkeley by Nobel Laureate William Giauque). Isotope geochemists measure these stable isotopes as ratios, 17O/16O or 18O/16O, which have a relationship with slope ~0.5. However, in ozone (O3) formation, the resulting ozone is equally enriched in 17O and 18O relative to 16O and the 17O/16O vs 18O/16O relationship has a slope of 1. This is dubbed mass-independent fractionation (O-MIF). In the stratosphere, ozone can photochemically transfer its O-MIF to carbon dioxide (CO2). However, there are large differences between the 17O/18O slope in stratospheric CO2, in the laboratory when CO2 is exposed to ozone, and in different stratospheric regions. My research will probe a hypothesized temperature dependence of O-MIF transfer from ozone to CO2 using a novel measurement system. The O-MIF in CO2 forms the basis for many tracers of past climates for which knowing the magnitude of the temperature dependence of the O-MIF is critical.