In situ mass analysis of surface reactions using surface-enhanced Raman spectroscopy covering a wide range of frequencies

Abstract

Heterogeneous electrochemical and photoelectrochemical reactions occurring at a metal surface were observed in situ using surface-enhanced Raman spectroscopy (SERS), which simultaneously covers 10–1800 cm⁻¹ including both intramolecular skeletal vibrations in the fingerprint region and extramolecular surface–adsorbate vibrations in the terahertz (THz) region. While fingerprint vibrations are commonly used for chemical identification, THz vibrations can provide information about mass changes of surface adsorbates in a surface reaction. We demonstrate that such frequency-extended SERS can provide more comprehensive analytical information about surface reactions, which is a better alternative to the combined analysis of conventional SERS spectroscopy and mass spectrometry.