MEASUREMENTS AND CALCULATIONS OF CO2 ABSORPTION AT HIGH-TEMPERATURE IN THE 4.3 AND 2.7 MU-M REGIONS

Absorption by pure CO2 and CO2-N2 mixtures in the 4.3 and 2.7 mum regi ons has been measured with a grating spectrometer with spectral resolu tion of 0.75 and 2 cm-1, respectively and pressures between 0.03 and 1 atm, at room temperature and around 750 K. Measurements are compared with line-by-line calculations using the spectroscopic parameters cons idered for the 1991 edition of the HITRAN database and those calculate d by Wattson and Rothman (W-R database) with the Direct Numerical Diag onalization (DND) method. Lorentzian profiles modified by the introduc tion of a frequency- and temperature-dependent line shape corrective f actor chi have been used. At room temperature, calculations with the t wo databases are consistent and in good agreement with our experiments . At 750 K, calculations with HITRAN underestimate absorption both in the 4.3 and 2.7 mum regions, whereas those with the W-R database are i n good agreement with the measurements, with the latter slightly under estimating the absorption in the low frequency wing of the 4.3 mum ban d. This may be due to inaccuracies in the chi factors and the paramete rs of some hot bands.