Distinct nonlinear terahertz magnetic- and electric-field response of molecular systems

In this work we focus separately on the fundamental interactions of intense single-cycle THz magnetic and electric fields with molecular liquids. We demonstrate that intense THz magnetic fields, from table-top sources, are able to induce Faraday rotation in liquids in ultrafast timescales. Analogously to the electric Hall effect in conducting materials, this observation is explained in terms of a transient molecular Hall effect, due to an instantaneous optically induced polarization in the presence of the THz magnetic field and opens a new avenue for successful disentanglement of electronic versus nuclear dynamics in complex molecular liquids. Moreover, we show that by tuning the frequency and phase of the electric field of intense THz pulses we can achieve different molecular rotational distributions in liquids, paving the way not only for better fundamental understanding of the intermolecular interactions, but also for achieving THz coherent control of chemical reactions.