Dependence of the nascent vibrational distribution of NO(v) on the photolysis wavelength of NO2 in the range λ = 266–327 nm measured by time-resolved Fourier transform infrared emission

Abstract

Time-resolved FTIR has been used to study the photodissociation of NO₂ at photolysis wavelengths of λ = 266, 282, 295, 308, 320 and 327 nm. Nascent vibrational distributions of the NO(v) fragment have been determined at all wavelengths: 266 nm photolysis populates NO(v = 1–7) and shows a distribution that is inverted at v = 5, whereas 327 nm photolysis populates NO(v = 1–3) and is inverted at v = 2. Surprisal plots were performed on the nascent distributions presented in this work and on all data sets available in the literature in the range 266–370 nm in order to parameterise the wavelength dependence of the nascent distribution of NO(v) from NO₂ photolysis. In general, the surprisal parameter was found to be a linear function of wavelength and was used to generate a simple model for the wavelength dependence of the nascent distribution of NO(v) in the region λ = 265–372.5 nm. The results give a more accurate parameterisation of the formation of NO(v) of use in atmospheric modelling.