Structure of interfacial water investigated by sum frequency generation (SFG) spectroscopy

Water is not just a solvent but also a reactant or product in many important electrocatalytic reactions. Thus, molecular-level understanding of the structure arrangement of water molecules at an electrode/electrolyte solution interfaces is one of the important issues in electrochemistry. We applied sum frequency generation (SFG) spectroscopy, which is an interface-selective probe, to compare the potential dependent interfacial water structure at Pt and Au thin film electrodes. We found that the structure of interfacial water is more highly oriented at the Pt electrode than at the Au electrode.

Surface reaction dynamics at solid/liquid interfaces investigated by time resolved SFG spectroscopy

The determination of time dependent structure of short-lived intermediates on surface is important in understanding surface chemical reactions. The observation of the species is, however, difficult by means of conventional surface vibrational techniques. Time-resolved vibrational spectroscopy using sum-frequency generation (TR-SFG) process is one of the powerful tools to investigate the ultrafast surface reaction dynamics. Transient site hopping behavior of CO adsorbed on Pt surface under electrochemical conditions was observed using TR-SFG initiated by picosecond laser pulse excitation.