in Fig. ). The figure reveals two peaks of vibrational origin: the first peak located around 2000 cm -1 (the period ∼ 17 fs) is attributed to the N --N stretch and the second peak located around 600 cm -1 (the period ∼ 56 fs) is attributed to the C-H out-of-plane motion. These two modes are assigned according to Table . Oscillations with a period of ∼ 17 fs are clearly seen in in Fig. . Furthermore, since the first-peak frequency is roughly thrice larger than the second-peak frequency vibration, every forth peak of the cold GSB signal in panel (b) is more pronounced. Physically, the strong oscillation patterns in the cold GSB signal are a manifestation of the significant dependence of TDMs on nuclear coordinates (non-Condon effect). Fig. shows the hot GSB signal. It emerges at 25 fs, indicating the starting of IC. Then the hot GSB signal exhibits quite irregular oscillations which somewhat resemble those in the SE and ESA signals in Fig. (b) and (c). For example, note a pronounced recurrence around 120 fs.