The UV-visible absorption cross-sections of IONO2

Abstract

The UV-visible absorption spectrum of gaseous IONO2 has been measured over the wavelength range 245-415 nm using the technique of laser photolysis with time-resolved UV-visible absorption spectroscopy. IONO 2 was produced in situ in the gas phase by laser flash photolysis of NO2/CF3I/N2 mixtures. Post flash spectra were deconvolved to remove contributions to the observed absorption from other reactant and product species. The resulting spectrum attributed to IONO 2 consists of several overlapping broad absorption bands. Assuming a quantum yield of unity for IONO2 photolysis, model calculations show that during sunlit hours at noon, 53° N, the first order solar photolysis rate coefficient (J value) for IONO2 is 4.0 × 10-2 s-1. © European Geophysical Society 2002.