Figure 4

Pressure evolution of Raman spectra (λ = 532 nm, T = 300 K).

From low to high wavenumber, phonon modes are denoted as M1, M2, M3, M4, M5, M6 and M7 at 0.9 GPa. The black squares are experimental data points, the red solid lines are the total fitting curves from the sum of the individual Lorentzian fits (blue peaks) to the experimental data points. Arrows mark the appearances of new vibration modes.