The time evolution of the SE and ESA spectra correlates with the torsional motion of the C3-N1-N2-C4 dihedral angle, as shown in Fig. . The C3-N1-N2-C4 dihedral angle is around 5 degrees in the first 5 fs, indicating that the trajectories are near the S 0 minimum, and the SE and ESA maxima reveal the VEEs in the Franck-Condon region. Since the S 1 -S 4 TDM dominates the short-time dynamics, the ESA maximum coincides with the S 1 -S 4 VEE. The subsequent decrease of the S 1 -S 4 TDM and increase of the S 1 -S 5 and S 1 -S 2 TDMs lead to the splitting of the ESA signal. Interestingly, the time evolutions of the SE and ESA spectra correlate with those of the C3-N1-N2-C4 dihedrals in many aspects: timescales, oscillation patterns, and so on. For example, maxima of the SE and ESA spectra around 120 fs in panels (b) and (c) correlate with the minimum of the dihedral angle in panel (d).