The Back Door to the Surface Hydrated Electron

J Mato and SY Willow and JC Werhahn and SS Xantheas, JOURNAL OF PHYSICAL CHEMISTRY LETTERS, 14, 8221-8226 (2023).

DOI: 10.1021/acs.jpclett.3c01479

We use a Mg+ metal to extend the size regime of aqueous clusters to extrapolate to the bulk limit of the vertical detachment energy (VDE) of the solvated electron to >3,200, a value between 1 to over 2 orders of magnitude larger than the one previously measured experimentally or computed theoretically. We relate the VDE to the energy difference between the Mg+(H2O)(n) and Mg2+(H2O)n systems and the metal's second ionization potential. The extrapolated bulk VDEs of the localized surface electron, which moves away from the metal as n increases, are 1.89 +/- 0.01 eV for semiempirical (n similar to 3,200; PM6-D3H4) and 1.73 +/- 0.03 eV (n similar to 150; HF) and 1.83 +/- 0.02 eV (n similar to 150; MP2) for ab initio, in excellent agreement with the 1.6-1.8 eV range of experimental results. The VDEs converge from above (larger values) to the bulk limit, in a manner that is qualitatively opposite from previous studies and experiments lacking a charged metal, a fact justifying the "back door" approach to the solvated electron.

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