Dynamics of excited state electron transfer at a liquid interface using time-resolved sum frequency generation

► Femtosecond time resolved vibrational SFG has been used for the first time to probe interfacial chemical reactions. ► We obtained the ultrafast dynamics of electron transfer at a water/DMA monolayer interface. ► The forward electron transfer at the interface faster than electron transfer in bulk DMA. ► The faster rate is attributed to a lower reorganization free energy at the interface.