Coherent wavepacket motion in an ultrafast electron transfer system monitored by femtosecond degenerate four-wave-mixing and pump-probe spectroscopy

- Coherent wavepacket motion was investigated for ultrafast electron transfer (ET) system.
- Vibrations originating from ground and excited states were extracted with high accuracy.
- The dephasing of the excited state vibration was accelerated by the ultrafast ET.

Coherent nuclear wavepacket motions were monitored by three types of femtosecond time-resolved spectroscopy, namely, transient absorption measurement utilizing white-light supercontinuum (WC-TA), degenerate four-wave-mixing (DFWM), and pump-probe (PP) measurements, for an ultrafast intermolecular electron transfer (ET) system with a dye molecule, oxazine 1 (Ox1), dissolved in an electron donating solvent, N,N-dimethylaniline (DMA). Vibrational frequencies of the wavepacket motion in the excited and in the ground states were 560-562 and 567-569 cm−1, respectively, with only a few frequency difference of 5-9 cm−1, which were clearly distinguishable by the highly accurate measurements. In DMA, the excited state wavepacket motion declined with time constant of 160-240 fs which is somewhat longer than that of the ultrafast ET; 60-80 fs.

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