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INitial TRAining network in Mass Independent Fractionation

ESR project 1: Investigation of isotope effects in O3 thermal decomposition

at LPMAA of CNRS/Université Pierre et Marie Curie, Paris, France
supervisor, C. Janssen, LPMAA >e-mail
co-supervisors M. S. Johnson, CCAR, and T. Röckmann, IMAU

Ozone formation is the ultimate source of most of the MIF signatures in the atmosphere and experiments on this molecule can provide new information on the origin of the effect. The best quantitative theory proposed so far (Gao & Marcus 2001) predicts almost equal isotope enrichments for 17O and 18O substituted isotopomers at ambient temperatures and above, but measurements (Morton et al. 1990) indicate that this might not be true. High temperature data will be a crucial test for theories. In order to study O3 isotope chemistry at temperatures above 350 K, one must investigate thermal decomposition of O3, the inverse of the formation reaction. So far, attempts to study this reaction (Wen & Thiemens 1990, 1991) have not been successful in that they could not quantitatively recover the effect observed in the formation reaction. The experimental problems (like surface decomposition) of earlier studies can be overcome by employing in-situ detection using tunable diode laser absorption spectroscopy (TDLAS), a technique recently developed for symmetry selective detection of ozone isotopomers (Janssen & Tuzson 2006). The TDLAS technique will also be used in ESR projects 3, 4, 5, 6 and 7.