Fig. 7

Examples of Raman spectra of pure H₂O in the high-frequency range (3000–4000 cm⁻¹) at temperatures and pressures indicated on each spectrum. Spectra are normalized to the same acquisition time and slit width and then normalized to the maximum intensity within each spectrum, A 3600 cm⁻¹ envelope at temperature/pressure conditions indicated on each spectrum. Intensities are normalized to the highest intensity point in each spectrum. B Difference spectra relative to 800 °C/1.44 GPa spectrum as indicated by temperature. C Evolution of full width at half height as a function of temperature (and pressure—see Fig. 2)