Fig. 2
From: Evidence of a one-dimensional thermodynamic phase diagram for simple glass-formers
Picosecond dynamics at various state points for PPE, cumene and DPG. Top panel: (T, P)-phase diagram showing the state points of the spectra in row a–c. The black lines correspond to the glass transition isochrones with τ α  = 100 s. All spectra are plotted in reduced units, \(\tilde \omega = \omega \rho ^{ - 1/3}T^{ - 1/2}\) and summed over Q. a Spectra in the liquid: at low pressure, we primarily observe relaxation. As pressure is increased, reaching the glass transition, only fast relaxation and vibrations are left. b Spectra in the glass: leaving the glass transition, going deeper into the glass, fast relaxations disappear and only vibrations are left. c Along the glass transition isochrones, there is superposition of dynamics for the two van der Waals liquids, PPE and cumene, while in the hydrogen bonding liquid, DPG, there is a clear shift in the data with pressure. PPE and cumene were measured on IN5 and DPG on IN6. No scaling has been done on the y-axis, i.e. all spectra are shown on the same \(S(\tilde \omega )\) scale
