The separation of overlapping transitions in -carotene with broadband 2D electronic spectroscopy

Broadband 2D electronic spectroscopy is applied to β -carotene, revealing new insight into the excited state dynamics of carotenoids by exploring the full energetic range encompassing the S 0 → S 2 and S 1 → S 1 n transitions at 77 K. Multiple signals are observed in the regime associated with the proposed S∗ state and isolated through separate analysis of rephasing and nonrephasing contributions. Peaks in rephasing pathways display dynamic lineshapes characteristic of coupling to high energy vibrational modes, and simulation with a simple model supports their assignment to impulsive stimulated Raman scattering. A signal persisting beyond 10 ps in the nonrephasing spectra is still under investigation.