The Back Door to the Surface Hydrated Electron.

Area of Science:

• Physical Chemistry
• Computational Chemistry
• Materials Science

Background:

• The vertical detachment energy (VDE) of solvated electrons is crucial for understanding electron localization in aqueous systems.
• Previous experimental and theoretical studies were limited in the size regime of aqueous clusters, hindering extrapolation to the bulk limit.

Purpose of the Study:

• To extend the size regime of aqueous clusters using a Mg+ metal.
• To extrapolate the VDE of the solvated electron to the bulk limit.
• To investigate the influence of a charged metal surface on VDE.

Main Methods:

• Utilized a Mg+ metal to create and study aqueous clusters of unprecedented size (>3,200 water molecules).
• Employed semiempirical (PM6-D3H4) and ab initio (HF, MP2) computational methods.
• Related VDE to the energy difference between Mg+(H2O)n and Mg2+(H2O)n systems and the metal's second ionization potential.

Main Results:

• Extrapolated bulk VDEs for the solvated electron were found to be significantly larger than previously reported, reaching >3,200.
• Semiempirical calculations yielded a VDE of 1.89 ± 0.01 eV (n ~ 3,200).
• Ab initio calculations (HF, MP2) provided VDEs of 1.73 ± 0.03 eV and 1.83 ± 0.02 eV, respectively (n ~ 150), agreeing well with experimental ranges (1.6-1.8 eV).

Conclusions:

• The use of a charged Mg+ metal enables a "back door" approach to studying solvated electrons.
• VDEs converge from above to the bulk limit, a behavior opposite to previous findings without a charged metal.
• This study significantly advances the understanding of electron behavior in bulk water.