Fractionation of 14N15N16O and 15N14N16O During Photolysis at 213 nm
Hui Zhang, P.O. Wennberg, V.H. Wu, G.A. Blake
Submitted to Geophys. Res. Lett., 1999.
Motivated by Yung and Miller's suggestion [1997] that N2O is isotopically fractionated during UV photolysis in the stratosphere, we have studied the photolysis rates of the 14N15N16O and 15N14N16O structural isotopomers. In this study, we follow the concentrations of these compounds with FTIR spectroscopy during photolysis at 213 nm. Our results show that, as Yung and Miller predicted, the photolysis rate of15N14NO is faster than 14N15NO at this wavelength. When fitted to a Rayleigh fractionation model, the observations yield single-stage enrichment factors of (14N15N16O / 14N14N16O) = -73 +- 5 per mil and (15N14N16O / 14N14N16O) = -41 +- 10 per mil. Comparisons are provided with theoretical calculation and previous measurements.