Atmospheric Chemistry and Physics www.atmos-chem-phys.net 1680-7316 1680-7324 4 5 2004 10.5194/acp-4-1237-2004 http://www.atmos-chem-phys.net/4/1237/2004/ http://www.atmos-chem-phys.net/4/1237/2004/acp-4-1237-2004.html http://www.atmos-chem-phys.net/4/1237/2004/acp-4-1237-2004.pdf 1237 1253 2004-08-10 Ultra-violet absorption cross sections of isotopically substituted nitrous oxide species: ¹⁴N¹⁴NO, ¹⁵N¹⁴NO, ¹⁴N¹⁵NO and ¹⁵N¹⁵NO P. von Hessberg J. Kaiser M. B. Enghoff C. A. McLinden S. L. Sorensen T. Röckmann M. S. Johnson Department of Chemistry, University of Copenhagen, Copenhagen, Denmark Max-Planck Institute for Nuclear Physics, Atmospheric Physics Division, Heidelberg, Germany Air Quality Research Branch, Meteorological Service of Canada, Toronto, Ontario, Canada Synchrotron Radiation Research, Lund University, Lund, Sweden now at Department of Geosciences, Princeton University, Princeton, New Jersey, USA The isotopically substituted nitrous oxide species ¹⁴N¹⁴NO, ¹⁵N¹⁴NO, ¹⁴N¹⁵NO and ¹⁵N¹⁵NO were investigated by ultra-violet (UV) absorption spectroscopy. High precision cross sections were obtained for the wavelength range 181 to 218nm at temperatures of 233 and 283K. 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 N₂O in the stratosphere, and the results were found to be in good agreement with field studies.