The role of molecular vibration in photoinduced electron transfer (ET) reactions has been extensively debated in recent years. In this study, we investigated vibrational wavepacket dynamics in a model ET system consisting of an organic dye molecule as an electron acceptor dissolved in various electron donating solvents. By using broad band pump-probe (BBPP) spectroscopy with visible laser pulses of sub-10 fs duration, coherent vibrational wavepackets of naphthacene dye with frequencies spanning 170-1600 cm-1were observed in the time domain. The coherence properties of 11 vibrational modes were analyzed by an inverse Fourier filtering procedure, and we discovered that the dephasing times of some vibrational coherences are reduced with increasing ET rates. Density functional theory calculations indicated that the corresponding vibrational modes have a large Huang-Rhys factor between the reactant and the product states, supporting the hypothesis that the loss of phase coherence along certain vibrational modes elucidates that those vibrations are coupled to the reaction coordinate of an ET reaction.
|Number of pages||12|
|Journal||Journal of the American Chemical Society|
|State||Published - Sep 15 2021|
Bibliographical noteFunding Information:
This work was supported by JSPS KAKENHI Grant Numbers JP26107002 and JP16J00627. Financial support for the ultrafast spectroscopy work was provided by the Division of Chemical Sciences, Geosciences, and Biosciences, Office of Basic Energy Sciences, of the U.S. Department of Energy through Grant No. DE-SC0015429. Y.Y. appreciates the support of the Interactive Materials Science Cadet (IMSC) program for research abroad. B.K. acknowledges the NSF for a Graduate Research Fellowship (DGE-1656466). The authors would like to thank Kiho Nishioka, Kenya Tanaka, and Shuji Nakanishi for their help with the cyclic voltammetry measurement.
© 2021 American Chemical Society
ASJC Scopus subject areas
- Chemistry (all)
- Colloid and Surface Chemistry