Probing vibrational dynamics of PM650 with two-dimensional electronic spectroscopy

► Two dimensional electronic spectroscopy of pyrromethene 650. ► PM650 demonstrates vibrational coherence beating signals in 2D spectroscopy. ► PM650 exemplifies limiting case of solely vibrational coherences. ► Signal shows beating throughout spectrum in rephasing and nonrephasing signals. ► Beating pattern in contrast to quantum beats attributed to electronic coherences.