Dielectron attachment and hydrogen evolution reaction in water clusters.

Area of Science:

• Physical Chemistry
• Computational Chemistry
• Chemical Physics

Background:

• Excess electron binding to water clusters is crucial for understanding electron solvation.
• Doubly charged water clusters remain largely unexplored despite their potential unique properties.

Purpose of the Study:

• Investigate the properties of excess electrons in nanosize water droplets, particularly doubly charged clusters.
• Elucidate the electronic states and reaction mechanisms of charged water clusters.

Main Methods:

• Experimental investigation using mass spectrometry.
• Theoretical analysis with large-scale first-principles simulations based on spin-density-functional theory.
• Quantum mechanical treatment of all valence and excess electrons.

Main Results:

• Singly charged clusters (H2O)n(-1) detected for n = 6-250, with calculated energies matching experimental data.
• Doubly charged clusters (H2O)n(-2) observed for 83 ≤ n < 105.
• For n ≥ 105, mass-shifted peaks indicated (H2O)n-2(OH(-))2 formation, driven by dielectron localization and proton transfer.

Conclusions:

• The study provides a consistent interpretation of excess electron states in singly charged water clusters.
• Dielectron localization modes were identified in doubly charged clusters.
• A reaction mechanism for doubly charged clusters (n ≥ 105) forming H2 was elucidated, dependent on dielectron internal localization stability.