Two-dimensional terahertz spectroscopy of condensed-phase molecular systems

Nonlinear terahertz (THz) spectroscopy relies on the interaction of matter with few-cycle THz pulses electric field amplitudes up to megavolts/centimeter (MV/cm). In condensed-phase molecular systems, both resonant interactions elementary excitations at low frequencies such as intra- and intermolecular vibrations nonresonant field-driven processes are relevant. Two-dimensional (2D-THz) is a key method for following nonequilibrium dynamics decipher underlying couplings. This article addresses state art in 2D-THz by discussing main concepts illustrating them recent results. The latter include response vibrational crystals nonperturbative regime light–matter ionization electron transport liquid water.