Atmospheric Physics and Chemistry Group (APCG)


Past Projects

Isotope effects in ozone formation and destruction reactions

Marion Fruechtl


Ozone is of great importance for the chemistry of the atmosphere and its isotopic signature affects that of many other trace constituents. Due to differences in chemical and physical properties, most of the isotope fractionations are dependent on mass and follow the fractionation (MDF) equation Δ17O = δ17O – 0.52 * δ18O. However, many atmospheric components show an oxygen isotope anomaly, defined as the excess 17O over what is expected based on 18O isotopic abundances. The processes that generate such deviations in 17O are termed mass-independent fractionations (MIF).
An unusual, very strong, isotope effect is involved in the ozone formation. This isotope anomaly can be transferred to other species via chemical reactions in the atmosphere and this allows studying reaction pathways in detail. Recent results indicate that there may be secondary isotope effects associated with the O3 destruction reactions, which have not been studied in detail in the laboratory.
Within the framework of INTRAMIF (Initial Training Network on Mass-Independent Fractionation) we are setting up new experiments to characterize the effect of various destruction reactions (photolysis, reactions with other compounds) on the isotopic composition of ozone.