Fig. 3

Examples of Raman spectra in the 300–1200 cm⁻¹ frequency range of fluids from systems without SiO₂. A ReO₂–H₂O and B Na₂O–ReO₂–H₂O at the temperatures and pressures indicated on the individual spectra. Inserts show the temperature evolution of the individual Raman bands. Pressures corresponding to each temperature can be read off Fig. 2. In this and subsequent figures, the Raman intensities are normalized to the same Raman setup parameters (acquisition time and slit width)