Far-infrared absorption of CO2 clathrate hydrate

CO₂ clathrate hydrate is believed to form in the polar regions of Mars in winter. In order to verify its presence in a remote sensing experiment, its dielectric properties must be known and must be sufficiently different from those of water ice, CO₂ ice, and CO₂ gas to give a distinct signature. The authors present their measurement of the far-infrared spectra of CO₂ clathrate hydrate. The spectrum exhibits a broad absorption that is probably due to a rattling mode of the CO₂ molecules in their water ice cages. They discuss the feasibility of using this absorption in a remote sensing experiment