in situ FTIR Spectroscopic Characterization of Electroactive Species

A spectroelectrochemical technique based on the Fourier Transform Infrared Reflection Absorption Spectroscopic (FTIR-RAS) method is described, whereby high resolution in situ vibrational spectra of electrogenerated reaction intermediates (including radicals) and species adsorbed on electrode surfaces are obtained. Theoretical and experimental aspects of the method in a single reflection mode are discussed. Details of the cell design and the optimization of the operational parameters for running the FT-IR spectrometer in the RAS mode are also described. Apart from the potential of this technique to identify adsorbed species through their vibrational spectra, it can also be used to determine the orientation of the adsorbed species on the electrode surface by making use of surface selection rules. Using this technique, it has been possible to record the spectra of molecules adsorbed from aqueous and non aqueous media on metal and carbon electrodes. It has been possible to distinguish the vibrational spectra of adsorbed molecules from those in the bulk. Various systems covering a wide range of molecules have been studied and the potential of the technique as a method for the characterization of the electrode-electrolyte interface has been demonstrated.