Berlin 2005 – wissenschaftliches Programm

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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).