We aim at understanding the low-energy molecular dynamics in liquids. We employ both linear and non-linear THz spectroscopy
to explore the nature of the complex molecular motions and map the energy potential of their intermolecular interactions.
As shown schematically in the figure, THz electric fields couple into the permanent dipole moment of liquids and
induce non-linear effects. By a proper probe (THz or optical pulse) the underlying dynamics can be directly monitored.