Ground and space based observatories: the feasibility of measuring D/H in exoplanet atmospheres

The D/H ratio is a powerful window into the evolution of atmospheres. Atmospheric escape results loss of the lighter isotope, which, in the Solar System, has allowed us to conclude that Mars and Venus lost significant amount of water. Measuring the D/H ratio in exoplanet atmospheres is possible by looking at the absorption/emission features of water or methane in the mid-infrared. Even at natural isotopic abundances, the deuterated isotopes have regions where the absorption surpasses the main isotopes. The ro-vibrational opacities of the relevant couples (i.e. H2O/HDO and CH4/CH3D) have to be very well constrained however. Combining both experimental and ab-initio line lists offers the most complete and accurate way to calculate molecular absorptions. We combine these datasets, and the feasibility of detecting D/H in exoplanets is assessed using both ground and space based observatories, and considering a number of different atmospheres and planetary sizes.