Experimental CO2 absorption coefficients at high pressure and high temperature

Here we present a laboratory study of CO2 absorption spectra, obtained at high temperatures and pressures, similar to those encountered in the Venusian atmosphere. These spectra have been recorded using a Fourier Transform InfraRed (FT-IR) spectrometer , which is equipped to operate from 800 to 30,000 cm−1 (0.33-12.5μm) with a resolution from 0.06 to 10 cm−1. A dedicated gas cell, designed to support pressures up to 200 bar and temperatures up to 350 °C, has been coupled to the FT-IR. Starting from a realistic vertical pressure-temperature profile of the Venus' atmosphere, based on measurements performed with atmospheric probes, we have recorded a series of absorption spectra of CO2, varying the pressure and temperature from 1 to 50 bar and from 294 to 650 K.

► We report CO2 absorption spectra recorded between 0.33 and 12.5μm at high temperatures and pressures. ► The pressure and temperature conditions are chosen according to the VIRA model describing Venus' atmosphere. ► Collision induced bands have been observed as well. ► The spectra are useful for radiative transfer calculations of planetary atmospheres. ► All data are available on a dedicated web site.