Fractional revivals of wave packets in the A1∑u+ state of K2. A comparison of two different pump and probe cycles by spectrograms

New wave packet propagation phenomena have been investigated for the potassium dimerʹs electronic A1∑u+ state. Different pump and probe cycles (two (TPI) and the three (3PI) photon ionization) are applied mirroring the wave packet dynamics in specific ways. By means of spectrograms pronounced revival structures can vividly be visualized. While the real-time spectrum of the 3PI process shows an alternation in time of total and fractional revivals with 500 and 250 fs periods, respectively, the transient TPI spectrum reveals the same periods, however, now occurring simultaneously. This enables an unambiguous analysis of the different ionization pathways induced by TPI and 3PI processes.