In-Situ Ultra-Low Frequency SERS Observation at Electrified Interfaces

Abstract

Surface-selective spectroscopy is a powerful tool to study various interfacial phenomena such as electrochemical reactions at electrode/electrolyte interfaces. However, structural information on the solid and liquid phases next to the interface have been separately observed using different spectroscopic methods: e.g., X-ray spectroscopy for solid phases and vibrational spectroscopy for liquid phases. Recently, we have extended the detectable frequency range of surface enhanced Raman scattering (SERS) into the ultra-low frequency region down to 10 cm-1, which corresponds to THz region [1]. This enables us to observe not only molecular vibrations but also extramolecular vibrations and surface phonons of the metal lattice [2]. These information should provide deeper insight into catalytic and electrocatalytic reaction mechanisms. In this talk, we will demonstrate in-situ and simultaneous detection of vibrational information on both solid-electrode and liquid-electrolyte phases at the interface. [1] M. Inagaki, K. Motobayashi, K. Ikeda, “Electrochemical THz-SERS Observation of Thiol Monolayers on Au(111) and (100) Using Nanoparticle-assisted Gap-Mode Plasmon Excitation” J. Phys. Chem. Lett., 8, 2017, pp. 4236-4240. [2] M. Inagaki, K. Motobayashi, K. Ikeda, submitted.