New infrared spectroscopic database for bromine nitrate

Abstract

Fourier transform infrared measurements of bromine nitrate have been performed in the spectral region 675–1400 cm−1 at 0.014 cm−1 spectral resolution. Absorption cross sections were derived from 38 spectra covering the temperature range from 203 to 296 K and air pressure range from 0 to 190 mbar. For line-by-line analysis, further spectra were recorded at 0.00094 cm−1 spectral resolution at 223 and 293 K. The sample was synthesized from ClONO2 and Br2. Band strengths of the bands nu3 around 803 cm-1 and nu2 around 1286 cm-1 were determined from three pure BrONO2 measurements at different temperatures and pressures. Number densities in the absorption cell were derived from pressure measurements of the purified sample taking into account small amounts of impurities determined spectroscopically. Resulting band strengths are Snu3 = 2.872(52)×10-17 cm2molec-1cm-1 and Snu2 = 3.63(15)×10-17 cm2molec-1cm-1. Absorption cross sections of all measurements were scaled to these band strengths. Further data reduction was achieved with an interpolation scheme based on two-dimensional polynomials in ln(pressure) and temperature. The database is well-suited for remote-sensing application and should reduce the atmospheric bromine nitrate error budget substantially.