Monitoring results of Na-clathrite synthesis. Each pressure, temperature, and Raman measurement was labelled with the initial letter of ‘time’ in capital letters followed by a number in ascending order. (A) Top: pressure-temperature-time path diagram for CO₂ clathrate hydrate formation-dissociation and carbonate precipitation, divided into two stages: cooling and heating. Breaks in experimentation, due to the end of the working day, are illustrated as interruptions in the timeline. Each square dot represents a Raman measurement labelled from T0 to T30, with T0 being the first measurement under closed system conditions. (A) Bottom: plot of Raman position of the lower (νl) and upper bands (ν_u) of the CO₂ Fermi diads in the gas, solvated, and clathrate phase vs. the full width at half-maximum value. (B) Crystallisation of sodium carbonate phase for the stretching ν₁ mode. (C) Bending ν₄ mode positions of carbonate group on the CO₂-clathrate hydrate formation-dissociation curve.