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UP: Umweltphysik
UP 16: Atmosph
ärische Spurengase und Aerosole: Laboruntersuchungen
UP 16.2: Fachvortrag
Mittwoch, 9. März 2005, 15:30–15:45, TU TA201
Ozone isotopomer distribution from its formation reaction — •Christof Janssen, Bela Tuzson, and Konrad Mauersberger — MPI für Kernphysik, Saupfercheckweg 1, 69117 Heidelberg
The formation of ozone O + O2 + M → O3 + M (R1) shows a large and exceptional oxygen isotope anomaly, that may serve as tracer for atmospheric oxidation [1]. Transfer of the anomaly into stratospheric CO2 has already been demonstrated and the isotopic signature of N2O may also in part originate from ozone related chemistry [2]. Presently, several questions remain open. Most importantly, the details of the above transfer pathways as well as the origin of the isotope anomaly in ozone are not fully understood.
We present diode laser based measurements of the isotope specific rate coefficients of the ozone forming reaction (R1) for all five isotopomers relevant to the atmosphere. The results confirm that the isotope effect in ozone formation is driven by large differences in zero-point energies and also has a contribution from molecular symmetry [3]. Implications for the isotope transfer mechanism into CO2 are discussed.
[1] Brenninkmeijer, C.A.M. et al., Chem. Revs. 103, 5125 (2003).
[2] Röckmann, T. et al., Geophys. Res. Lett. 28, 503, (2001).
[3] Janssen, C. et al., Phys. Chem. Chem. Phys. 3, 4718 (2001).
[4] Lämmerzahl, P. et al., Geophys. Res. Lett. 29, (2002).