Ultrafast 2D–IR Spectroscopy of Transient Species

Multidimensional spectroscopic experiments offer fascinating insights into molecular structure and dynamics in the field of NMR spectroscopy. With the introduction of ultrafast two-dimensional infrared spectroscopy (2D–IR), multidimensional concepts have entered the optical domain, measuring couplings and correlations between molecular vibrations with femtosecond time resolution. In the transient 2D–IR (T2D–IR) experiments described in this minireview we exploit the high time resolution of 2D–IR to study transient species during fast nonequilibrium processes in real time. Information on molecular structure and dynamics is obtained that is not available from one-dimensional spectroscopy. We discuss examples from chemistry, physics and biophysics.