Atmos. Chem. Phys. Discuss., 2, 1735-1763, 2002 Creative Commons
Attribution-NonCommercial-ShareAlike 2.5 License. Review Status
Wavelength dependence of isotope fractionation in N2O photolysis
J. Kaiser1, T. Röckmann2, C. A. M. Brenninkmeijer1, and
P. J. Crutzen1,3 1Abteilung Chemie der Atmosphäre, Max-Planck-
Institut für Chemie, Mainz, Germany 2Bereich Atmosphärenphysik,
Max-Planck-Institut für Kernphysik, Heidelberg, Germany
Abstract. In previous reports on isotopic fractionation in the
ultraviolet photolysis of nitrous oxide (N2O) only enrichments
of heavy isotopes in the remaining N2O fraction have been found.
However, most direct photolysis experiments have been performed
at wavelengths far from the absorption maximum at 182 nm. Here
we present high-precision measurements of the 15N and 18O
fractionation constants (e) in photolysis at 185 nm. Small, but
statistically robust depletions of heavy isotopes for the
terminal atoms in the linear N2O molecule are found. This means
that the absorption cross sec