ACPD Atmospheric Chemistry and Physics Discussions ACPD 1680-7375 Copernicus GmbH Göttingen, Germany 10.5194/acpd-4-2333-2004 Ultra-violet absorption cross sections of isotopically substituted nitrous oxide species: <sup>14</sup>N<sup>14</sup>NO, <sup>15</sup>N<sup>14</sup>NO, <sup>14</sup>N<sup>15</sup>NO and <sup>15</sup>N<sup>15</sup>NO von Hessberg P. 1 Kaiser J. 2 3 Enghoff M. B. 1 McLinden C. A. 4 Sorensen S. L. 5 Röckmann T. 2 Johnson M. S. 1 Department of Chemistry, University of Copenhagen, Copenhagen, Denmark Max-Planck Institute for Nuclear Physics, Atmospheric Physics Division, Heidelberg, Germany now at: Department of Geosciences, Princeton University, Princeton, New Jersey, USA Air Quality Research Branch, Meteorological Service of Canada, Toronto, Ontario, Canada Synchrotron Radiation Research, Lund University, Lund, Sweden 05 05 2004 4 3 2333 2378 This is an open-access article ditributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. This article is available from http://www.atmos-chem-phys-discuss.net/4/2333/2004/acpd-4-2333-2004.html The full text article is available as a PDF file from http://www.atmos-chem-phys-discuss.net/4/2333/2004/acpd-4-2333-2004.pdf

The isotopically substituted nitrous oxide species <sup>14</sup>N<sup>14</sup>NO, <sup>15</sup>N<sup>14</sup>NO, <sup>14</sup>N<sup>15</sup>NO and <sup>15</sup>N<sup>15</sup>NO were investigated by ultra-violet (UV) absorption spectroscopy. High precision cross sections were obtained for the wavelength range 181 to 218 nm at temperatures of 233 and 283 K. These data are used to calculate photolytic isotopic fractionation constants as a function of wavelength. The fractionation constants were used in a three-dimensional chemical transport model in order to simulate the actual fractionation of N<sub>2</sub>O in the stratosphere, and the results were found to be in good agreement with field studies.