New experimental measurements of the H 2 -CO 2 Collision-Induced Absorption in the 3907, 4770 cm−1 spectral range from 241 to 498 K

The collision-induced absorption (CIA) of a H 2 -CO 2 mixture has been studied in the 3907, 4770 cm −1 spectral range for temperatures ranging from 241 to 498 K. The experiments were based on the use of a new high-resolution Fourier spectrometer coupled with an atmospheric simulation chamber. Binary absorption coefficients (BACs) were measured for the first time in the 4033, 4730 cm −1 spectral range at temperatures other than room temperature and are provided in tabular form. At room temperature, the results are compared with existing experimental data and theoretical coefficients, while for the other temperatures, only theoretical values are available. For all considered temperatures, we computed the theoretical integrated band intensity for the experimental BACs and the semi-empirical models. The calculations have been made over the reduced 4033, 4730 cm −1 spectral range, and the entire band, in order to explore the bias induced by using a restricted spectral region. Furthermore, the H 2 -CO 2 BACs were compared with the previously measured H 2 -H 2 and H 2 -He data. We observed an overall higher absorption of the H 2 -CO 2 BACs, with scaling factors ranging from six to sixteen with respect to the H 2 -H 2 BACs, and from nine to twenty-seven for the H 2 -He case, depending on the spectral region. Finally, we used an empirical approach, to parametrize the BACs using an exponential profile as a function of temperature, using a series of wavenumber-dependent coefficients, a n . These coefficients allow to interpolate the BACs in the temperature range covered by the measurements. • H 2 -CO 2 CIA measurements in the 3907, 4770 cm −1 spectral range from 241 to 498 K. • Comparison with existing experimental data and semi-empirical calculations. • Differences in the total opacity with respect to the pure H 2 and the H 2 -He CIA. • Experimental data fitted with an exponential profile.