Hydrogen forms in water by proton transfer to a distorted electron

Area of Science:

• Physical Chemistry
• Chemical Physics
• Computational Chemistry

Background:

• Solvated electrons are key intermediates in radiation chemistry.
• Their reactivity is crucial for understanding radiation-induced processes.
• Quenching by protons under acidic conditions limits their lifetime.

Purpose of the Study:

• To elucidate the ultrafast reaction mechanism between solvated electrons and protons in water.
• To determine the character (proton vs. electron transfer) of this fundamental reaction.
• To investigate the factors influencing the reaction kinetics.

Main Methods:

• Ab initio molecular dynamics simulations were employed.
• Molecular resolution was achieved to study the reaction pathway.
• The dynamics of electron and proton motion were analyzed.

Main Results:

• The reaction involves distortion and contraction of the hydrated electron.
• A rapid proton motion occurs along hydrogen bonds.
• The reaction terminates on a specific water molecule, indicating proton transfer.
• The reaction is not diffusion-limited due to desolvation penalties.

Conclusions:

• The electron-proton reaction in water is definitively a proton-transfer process.
• The reaction mechanism is molecularly resolved.
• Simulation results align with experimental kinetics measurements.