Using ultrafast X-ray spectroscopy and time-resolved X-ray scattering, researchers tied electronic-structure changes in a ruthenium-based proton-coupled electron transfer (PCET) system to the reorganization of surrounding water as a proton is gained.

Researchers combine X-ray techniques with simulations to study these ultrafast, coupled motions, highlighting the novelty and potential to apply the framework to more complex PCET systems.

The study focuses on a light-absorbing ruthenium complex that leverages proton transfer to isolate signals from electronic, proton, and solvent motion, clarifying PCET dynamics.

A key finding shows electronic changes at specific sites occur alongside broader solvent-network rearrangements, demonstrating the coupled evolution of electronic structure and solvent dynamics during PCET.

While X-ray scattering cannot directly observe protons, the team derives conclusions from agreement between experimental data and calculations.

The investigative approach blends chemRIXS and time-resolved X-ray scattering with time-dependent density functional theory and molecular dynamics to yield a site-specific reaction picture.

Experiments were conducted at SLAC’s LCLS with support from the DOE Office of Science, and additional work took place at PNNL and the University of Geneva, with LCLS-II upgrade expected to improve signal quality.

The work, conducted by a collaboration of Pacific Northwest National Laboratory, SLAC, and universities, captures real-time PCET driven by light and has been published in Nature Communications.

Significance lies in advancing understanding of energy-conversion processes and could inform designing more efficient catalysts, fuel cells, and flow batteries.

Overall, the study establishes a framework for directly studying coordinated electron-proton-water dynamics in fundamental chemical transformations and energy-related technologies.