Surface-selective vibrational spectroscopy is a powerful tool to study various interfacial phenomena such as electrochemical reactions at electrode/electrolyte interfaces. Among various spectroscopic methods, surface enhanced Raman scattering (SERS) is a promising method to conduct in-situ observation in IR- and THz-opaque media. According to recent technological advancements in fabrication of optical filters, elimination of Rayleigh scattering has become highly efficient. Thus, it is now expected that very low-frequency vibrations such as THz vibrations can be observed even in aqueous solutions [1]. Figure shows that an extramolecular vibration of benzenethiol monolayers with ultra-low frequency is indeed observable using this method. We will discuss charge transfer resonances at metal/molecule interfaces based on this low frequency vibration.

Figure caption

THz-SERS spectra of monolayers of benzenethiol derivatives on a roughened Au substrate

Reference

[1] M Inagaki, K. Motobayashi, K. Ikeda, J. Phys. Chem. Lett., 8, 2017, pp. 4236-4240.