Solvent signals in two-dimensional electronic spectroscopy

We report on properties of non-resonant signals of several commonly used solvents in two-dimensional electronic spectroscopy. The signals can be split into three types with different evolution in population time: an initial, rather strong coherent spike with non-periodic oscillatory phase behavior, periodic oscillatory signals mostly connected to Raman-active vibrational modes of the solvents and non-oscillatory long lived signals. The relative amplitudes of the contributions depend on the solvent. We propose a simple model for predicting spectral positions of the non-resonant solvent signals. The results can be used to facilitate the identification and distinction of solvent and sample cell signals from the sample signal in two-dimensional electronic spectroscopy.