Infrared spectra of the clathrate kinetics experiment performed at 165K. Spectra extracted after 1, 30, and 100 days of exposure of the ice film to CO₂ gas at 60 mbar are shown in the 4500–600 cm⁻¹ range in the left panel. The upper trace is the spectrum recorded just after evacuation of the gas at the end of the experiment after 118 days. A close-up on the gas and clathrate hydrate signatures in the ν₁ + ν₃ and 2ν₂ + ν₃ combinationmodes is shown in the right panel. Under each spectrum is shown the baseline-corrected spectrum of the contribution by the CO₂ in the clathrate cages after subtraction of the gas phase contribution to the spectrum. The CO₂ signatures inthe small (SC) and large (LC) cages of the clathrate hydrate are labelled in the upper trace. The lower trace is a model of the CO₂ gas phase at165K. See text for details.