Recent advances in prethermal chemistry: real-time probing of elementary electron transfer reactions

In liquids and electrolyte solutions, elementary radical reactions may be investigated on the time scale of molecular motions by femtosecond visible-IR absorption spectroscopy. Some studies devoted to the microscopic understanding of sub-picosecond prehydration electron transfer between an aqueous halide ion (Cl^-) and ionic acceptors (Cd⁺⁺, H⁺) are presented. Within an electron hydration regime, the one-electron reduction of a metallic ion or a hydrated proton (hydronium or dihydronium ion) is totally achieved in less than 2 × 10^-12 s at 294 K. The consequences of an early partition between reactive and nonreactive IR electronic pathways on the electron hydration process are discussed.