Ultra-violet absorption cross sections of isotopically substituted nitrous oxide species:: 14N14NO, 15N14NO, 14N15NO and 15N15NO

The isotopically substituted nitrous oxide species (NNO)-N-14-N-14, (NNO)-N-15-N-14, (NNO)-N-14-N-15 and (NNO)-N-15-N-15 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 N2O in the stratosphere, and the results were found to be in good agreement with field studies.