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Vibrational coherences and their time evolution are crucial for the correct description of the dynamical behavior of materials, also influencing the dynamics of electronic coherences and transport processes. For this reason, vibrational coherences are now becoming the subject of wider investigation, especially in the framework of 2D electronic spectroscopies. A correct interpretation of vibrational coherences in 2DES responses requires the comparison with Raman spectra. Here we propose a methodology that goes beyond the typical practice of merely looking for frequencies present in both signals. In particular, we discuss suitable experimental conditions and correction procedures that allows a direct comparison of Fourier spectra obtained from the analysis of the signal beating at specific coordinates in 2D maps with resonant and non-resonant Raman spectra, to clearly identify the vibrational modes more strongly coupled with the electronic transition. The advantages of this approach have been illustrated using Chl a chromophore as a case study.

The subtle details of energy transport in light-harvesting complexes remain still mostly unknown, especially in the ultrafast regime. In this issue of Chem, Schlau-Cohen and co-workers employ 2D spectroscopy to unveil the unforeseen role of a carotenoid molecule in the optimization of the energy flow among pigments.