In situ analysis of adsorbed molecules by microsurface-enhanced Raman scattering

Abstract

Surface-enhanced Raman microprobe spectroscopy (micro-SERS) and surface-enhanced resonance Raman microprobe spectroscopy (micro-SERRS) of organic molecules adsorbed on a metal surface is reviewed. Advantages and applications of these new vibrational spectroscopic methods, particularly for in situ study of the chemical identity, structure, orientation, chemical and electrochemical reaction of biomolecules, organic pollutants, dioxins (furans) and surfactants adsorbed at charged metal surfaces are discussed. Different applications show that this spectroscopic technique is a powerful in situ method to study the liquid/solid inteface at high resolution. Moreover, the high enhancement factor of the Raman scattering intensity creates a new technique for obtaining high-resolution vibrational spectra of organic molecules from dilute aqueous solution in an electrochemical cell down to 10^–9 mol dm^–3. It permits the acquisition of Raman spectra from electrode spots down to 1 µm in size or other forms of microsamples approaching the subpicogram level.