Materials in the glassy state are of great practical interest and can be found in many applications: silica glass as a construction or transport material, plastics which are generally at least partially glassy, or glassy metal alloys for advanced applications. However, the physical properties of these materials (e.g. the strength of a telephone screen) depend on the heat treatment they receive during their formation, and more specifically on the rate of cooling from the liquid state. While industrial glass manufacturing processes are obviously well mastered, the non-equilibrium thermodynamic nature of these systems makes it particularly difficult to investigate the physical mechanisms at work theoretically and numerically. This calls for an experimental approach aimed at probing these fundamental mechanisms.
The aim of this PhD thesis is to study experimentally the very non-equilibrium response of polar liquids, using a device recently developed in the laboratory which enables us to apply a very rapid temperature change to a liquid and follow its re-equilibration dynamics. Measurements of linear response should reveal more about the physical mechanisms governing equilibration, while non-linear measurements will provide information about the cooperative nature of structural rearrangements.