American Chemical Society
ja0c10626_si_001.pdf (3.8 MB)

Electron–Nuclear Dynamics Accompanying Proton-Coupled Electron Transfer

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journal contribution
posted on 2021-02-19, 01:13 authored by Yusuke Yoneda, S. Jimena Mora, James Shee, Brian L. Wadsworth, Eric A. Arsenault, Diptarka Hait, Gerdenis Kodis, Devens Gust, Gary F. Moore, Ana L. Moore, Martin Head-Gordon, Thomas A. Moore, Graham R. Fleming
Although photoinduced proton-coupled electron transfer (PCET) plays an essential role in photosynthesis, a full understanding of the mechanism is still lacking due to the complex nonequilibrium dynamics arising from the strongly coupled electronic and nuclear degrees of freedom. Here we report the photoinduced PCET dynamics of a biomimetic model system investigated by means of transient IR and two-dimensional electronic–vibrational (2DEV) spectroscopies, IR spectroelectrochemistry (IRSEC), and calculations utilizing long-range-corrected hybrid density functionals. This collective experimental and theoretical effort provides a nuanced picture of the complicated dynamics and synergistic motions involved in photoinduced PCET. In particular, the evolution of the 2DEV line shape, which is highly sensitive to the mixing of vibronic states, is interpreted by accurate computational modeling of the charge separated state and is shown to represent a gradual change in electron density distribution associated with a dihedral twist that occurs on a 120 fs time scale.