We report the development of the four wave mixing vibrational analog to 2D NMR and demonstrate its spectral selectivity, sensitivity to the interactions causing mode coupling, and ability to spectrally resolve isotopic mixtures. The method discriminates against uncoupled vibrational modes and isolates the features that are associated with intra- or intermolecular interactions.

• Received 21 May 1999

DOI:https://doi.org/10.1103/PhysRevLett.84.1411