UV absorption cross sections of HO2NO2 between 343 and 273 K

Abstract

The UV absorption spectrum of gas phase HO₂NO₂ (PNA, peroxynitric acid) was measured over the wavelength range 220 to 350 nm at temperatures between 273 and 343 K using a diode array spectrometer. Contributions to the measured spectra from HNO₃, H₂O₂ and NO₂ were subtracted by using mass spectral detection of HNO₃ and H₂O₂ and UV/Vis absorption for NO₂. Our HO₂NO₂ absorption spectra have been scaled to the previously reported absorption cross section data of Molina and Molina [L. T. Molina and M. J. Molina, J. Photochem., 1981, 15, 97] and Singer et al. [R. J. Singer, J. N. Crowley, J. P. Burrows, W. Schneider and G. K. Moortgat, J. Photochem. Photobiol., A: Chemistry, 1989, 48, 17] at 250 nm. Our measured HO₂NO₂ cross sections at wavelengths longer than 290 nm are compared with literature values and the discrepancies are discussed. An empirical parametrization of the measured HO₂NO₂ cross section temperature dependence for use in atmospheric model calculations is presented.