Knowledge Bank

We present measurements of the absorption by $CO2-N2$ mixtures in the $4.3\mu m$ region. Experiments have been made in the 300-800 K. and 0-60 bar ranges; they are in good agreement with previous determinations below 296 K. Frequency and temperature dependent factors $\chi$ are introduced in order to account for the sublorentzian behaviour of $CO2$ far line-wings. Their dependences on temperature are deduced from experimental results beyond the $4.3\mu m$ band-head in the 193-773 K range for both $CO2-CO2$ and $CO2-N2$ and fitted by simple analytical functions. Comparisons between experimental and theoretical spectra in both sides of the band ($2100-2600cm-1$ range) are presented. It is shown that calculations using $\chi$ factors are inaccurate near line-centers at elevated pressure.