Ultrafast charge delocalization dynamics in aqueous electrolytes: New insights from Auger electron spectroscopy

► Ultrafast charge transfer in aqueous electrolytes is observed in Auger spectroscopy. ► Delocalization time-scales for various cations, anions and water are probed. ► The influence of both the magnitude, sign of charge and size of ions is discussed. ► Future directions for studying ultrafast charge-transfer processes are identified.