Electrochemical Cells for Internal Reflection

Internal reflection avoids the complication of radiation absorption by the solvent. However, the problem of solubility of the various materials in contact with the solution remains as acute as for external reflection. Furthermore, the material which constitutes the working electrode is generally opaque to the infrared radiation. It is therefore necessary to reduce the thickness to a very thin film deposited on the surface of an infrared-transparent substrate. 

FIGURE 23. Schematic diagram of the electrochemical cell used for internal reflection, according to Ref. 52. 

Following the above review of the various spectroscopic techniques for in situ electrode/solution interface investigations, several points should be discussed. 

The first one concerns the use of polarization modulation in conjunction with Fourier transform infrared spectroscopy. Although this technique has only been developed recently, the first results are very encouraging. They demonstrate the feasibility of using PM-FTIRS to gain information on monolayers, or even submonolayers, of adsorbed species on metallic surfaces with a very low specific area. 

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