Phase-Resolved fs Coherence Spectroscopy

Here we introduce phase-resolved (PR)-FCS, derived from two-dimensional electronic spectroscopy (2DES) measurements. This yields FC spectra sensitive to amplitude and phase of vibrational, vibronic or electronic wavepackets evolving during the waiting time 𝑇. Whilst 2DES beatmaps are typically amplitude normalised, PR-FC spectra retain relative intensity information, proportional to displacements between potential energy surfaces and afford a higher SNR relative to 2DES. Thus, the method provides a straightforward route to assign excited state coherence, when complex-valued 2DES data are available.