Summarizing, the SE and ESA signals reveal the S 1 population dynamics and the C3-N1-N2-C4 torsion on the S 1 state. As the SE signal overlaps spectrally with the GSB signal (Fig. ), the ESA signal is much easier to follow. The cold GSB signal gives information on the vibrational wavepacket motion on the S 0 state. The hot GSB signal reflects the C3-N1-N2-C4 torsion on the S 0 after IC. The cis and trans photoreaction channels may be distinguished by monitoring the hot GSB signals.