Fig. 1.

Principle of coherent multidimensional spectroscopy of photoreactivity. (A) For illustration, we assume a photoreactive network composed of three chemical species connected by different reaction channels. (B) 2D frequency spectra of this network visualize the correlations of reactants and products. (C) Involved reactive modes and associated reaction pathways that are still not resolvable from 2D spectra are exposed by introducing a third frequency dimension.