Wavepacket spatial propagation

In addition to the phase modulation an even more pronounced amplitude modulation is observed (Fig. 8.12, top). After the first pre-pulse (red), the oscillating dipole (blue) is damped simultaneously with the temporal decrease in overlap of the nuclear wavefunctions propagating on the X S+ and the A S+ surface (Fig. 8.12, second panel). Due to the difference in position and shape of both surfaces, the freely evolving nuclear wavepackets get out of phase. Their spatial overlap ai(t) aj(t) rlri(R,t) fj R,t))ii is reduced, which is again a decisive factor for the electron dynamics [Eq. (8.12)]. Its decrease stops the electron dynamics as observable in the damping of the electric dipole oscillation and in the loss of control for large subpulse separations [69]. In this sense K2 is an example for the third factor in Eq. (8.12), which determines the electron dynamics. This third factor can be regarded as time-dependent EC overlap. 

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