Experimental measurements of collision-induced absorption (CIA) cross-sections for CO2-H2 and CO2-CH4 complexes were performed using Fourier transform spectroscopy over a spectral range of 100-500 cm and a temperature range of 200-300 K. These experimentally derived CIA cross-sections agree with the spectral range and temperature dependence of the calculation by \citeA{Robin}, however the amplitude is half of what was predicted. Furthermore, the CIA cross-sections reported here agree with those measured by \citeA{Turbet}. The CIA cross-sections can be applied to planetary systems with CO$_{2}$-rich atmospheres, such as Mars and Venus, and will be useful to terrestrial spectroscopists. Additionally, radiative transfer calculations of the early Mars atmosphere were performed and showed that CO2$-CH4 CIA would require surface pressure greater than 3 bar for a 10% methane atmosphere to achieve 273 K at the surface. CO2-H2, however, liquid water is possible with 5% hydrogen and less than 2 bar of surface pressure.

Experimental measurements of collision-induced absorption (CIA) cross-sections for CO-H2 and CO2-CH4 complexes were performed using Fourier transform spectroscopy over a spectral range of 100-500 cm and a temperature range of 200-300 K. These experimentally derived CIA cross-sections agree with the spectral range and temperature dependence of the calculation by Wordsworth (2017), however the amplitude is half of what was predicted. Furthermore, the CIA cross-sections reported here agree with those measured by Turbet (2019). The CIA cross-sections can be applied to planetary systems with CO2-rich atmospheres, such as Mars and Venus, and will be useful to terrestrial spectroscopists. Additionally, radiative transfer calculations of the early Mars atmosphere were performed and showed that CO2-CH4 CIA would require surface pressure greater than 3 bar for a 10% methane atmosphere to achieve 273 K at the surface. CO2-H2, however, liquid water is possible with 5\% hydrogen and less than 2 bar of surface pressure.

An unanswered question in planetary science is how could the early Martian atmosphere have maintained a greenhouse effect sufficient to allow for liquid water on the surface? A recent study by Wordsworth et al. (DOI:10.1002/2016GL071766) suggested that previously unaccounted-for collision-induced absorption (CIA) by carbon dioxide (CO2) and hydrogen gas (H2), and by CO2 and methane (CH4) could provide the additional atmospheric absorption needed to trap enough radiation to raise the Martian surface temperature above freezing. However, as CIA cross-sections for CO2-H2 and CO2-CH4 complexes do not exist in the literature, the authors could only use computational methods to simulate the CIA absorption cross-sections that they themselves identify in the study as needing experimental validation. Preliminary results will be presented from experimental measurements of the CIA cross-sections for CO2-H2 and CO2-CH4 complexes performed using Fourier Transform Spectroscopy. We have obtained Beam-time at the Canadian Light Source Far-IR beamline in late October and early November which will allow us to derive Cross-sections over a spectral range of 0-3000 cm-1 and a temperature range of 200-350 K. In addition to allowing us to experimentally validate the hypothesis of Wordsworth, the cross-sections so obtained can also be applied to other planetary systems with CO2-rich atmospheres, such as Venus, and will be useful to terrestrial spectroscopists.