Abstract:

　　Solvated electrons (es-) are among nature’s most powerful reactants, with over 2600 reactions investigated in bulk water. At water-vapor interface, e_s- may act differently because of their distinct solvation in the interfacial environment. By exposing a sodium atomic beam to a surfactant-coated salty water microjet, we localize both reagents involved in the solvated electron reaction, e_s- and benzyltrimethylammonium surfactant, in the near-surface region of water. The observation of evaporated trimethylamine and benzyl products and the associated diffusion-reaction calculations indicate that es- reacts on average within 20 Å of the surface, while trimethylamine evaporates from the top 40 Å and the escape depth exceeds 1400 Å for benzyl. These proof-of-principle experiments establish an approach for exploring the near-interfacial analogs of aqueous bulk-phase radical chemistry through the evaporation of reaction intermediates into the gas phase.