The very weak absorption continuum of CO2 is studied by Cavity Ring Down Spectroscopy in three 20 cm⁻¹ wide spectral intervals near the centre of the 1.74 µm window (5693 − 5795 cm⁻¹). For each spectral interval, a set of room temperature spectra is recorded at pressures between 0 and 10 bar thanks to a high pressure CRDS spectrometer. The absorption continuum is retrieved after subtraction of the contributions due to Rayleigh scattering and to local lines of CO2 and water (present as an impurity in the sample) from the measured extinction. Due to some deficiencies of the CO2 HITRAN2012 line list, a composite line list had to be built on the basis of the Ames calculated line list with line positions adjusted according to the Carbon Dioxide Spectroscopic Databank and self-broadening and pressure shift coefficients calculated with the Complex Robert Bonamy method. The local line contribution of the CO2 monomer is calculated using this list and a Voigt profile truncated at ±25 cm⁻¹ of the line centre. Line mixing effects were taken into account through the use of the impact and Energy Corrected Sudden approximations.
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