New infrared spectroscopic database for chlorine nitrate

Fourier transform infrared measurements of chlorine nitrate have been performed in the spectral region 500–<f>1330 cm−1</f> at 0.002–<f>0.008 cm−1</f> spectral resolution. Absorption cross sections were derived from 23 spectra covering the temperature range from 190 to <f>296 K</f> and air pressure range from 0 to <f>150 hPa</f>. For line-by-line analysis, further spectra were recorded at <f>0.00094 cm−1</f> spectral resolution at 190 and <f>296 K</f>. The sample was synthesized from <f>N2O5</f> and <f>Cl2O</f>. Number densities in the absorption cell were derived from pressure measurements of the purified sample. Quality assurance included measurements with different sample pressures, spectroscopic purity check of the sample, comparison of integrated absorption cross sections over entire band systems, and assessment of residuals from remote-sensing retrievals. Multiplicative and additive errors were considered giving an overall uncertainty of <f>+2.5/−3.5</f>%. Further data reduction was achieved with an interpolation scheme based on two-dimensional polynomials in ln(pressure) and temperature. The worst-case error for the interpolated data is <f>+4.5/−5.5</f>%. The database is well-suited for remote-sensing application and should reduce the atmospheric chlorine nitrate error budget substantially. [Copyright &y& Elsevier]