With the intensive development of ultrafast spectroscopic techniques, reaction dynamics and transition states can be investigated
at the subpicosecond time scale (0.05–3 ps). Aqueous ionic solutions represent a paradigm for the characterization of elementary
chemical steps at the microscopic level. The discrimination of very short-lived electronic states during electron transfers
in molecular liquids provide guidance for further theoretical developments on non-reactive and reactive dynamics in complicated
many body systems.