Direct observation of coherent femtosecond solvent reorganization coupled to intramolecular electron transfer

Elisa Biasin*, Zachary W. Fox, Amity Andersen, Kathryn Ledbetter, Kasper S. Kjær, Roberto Alonso-Mori, Julia M. Carlstad, Matthieu Chollet, James D. Gaynor, James M. Glownia, Kiryong Hong, Thomas Kroll, Jae Hyuk Lee, Chelsea Liekhus-Schmaltz, Marco Reinhard, Dimosthenis Sokaras, Yu Zhang, Gilles Doumy, Anne Marie March, Stephen H. SouthworthShaul Mukamel, Kelly J. Gaffney, Robert W. Schoenlein, Niranjan Govind, Amy A. Cordones, Munira Khalil

*Corresponding author for this work

Research output: Contribution to journalJournal articlepeer-review

Abstract

It is well known that the solvent plays a critical role in ultrafast electron-transfer reactions. However, solvent reorganization occurs on multiple length scales, and selectively measuring short-range solute–solvent interactions at the atomic level with femtosecond time resolution remains a challenge. Here we report femtosecond X-ray scattering and emission measurements following photoinduced charge-transfer excitation in a mixed-valence bimetallic (FeiiRuiii) complex in water, and their interpretation using non-equilibrium molecular dynamics simulations. Combined experimental and computational analysis reveals that the charge-transfer excited state has a lifetime of 62 fs and that coherent translational motions of the first solvation shell are coupled to the back electron transfer. Our molecular dynamics simulations identify that the observed coherent translational motions arise from hydrogen bonding changes between the solute and nearby water molecules upon photoexcitation, and have an amplitude of tenths of ångströms, 120–200 cm−1 frequency and ~100 fs relaxation time. This study provides an atomistic view of coherent solvent reorganization mediating ultrafast intramolecular electron transfer. [Figure not available: see fulltext.]

Original languageEnglish
JournalNature Chemistry
Volume13
Issue number4
Pages (from-to)343-349
Number of pages7
ISSN1755-4330
DOIs
Publication statusPublished - 2021

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