Reflection special electrode configuration

The electrode substrate for the reflection measurement is not necessarily in the form of a flat plate in a quiescent electrolyte solution but sometimes in the form of a sphere or in a hydrodynamic condition. We here consider three typical examples of in-situ UV-visible reflectance measurement in special electrode configurations. 

The first method employing internal reflection requires special cell and electrode configurations. The very thin metal (or oxide) film electrode needs to be evaporated on an optical material such as a quartz prism. It makes routine surface pretreatment and measurement very difficult, and indeed, this method has not been adapted commonly in spectroelec-trochemistry. The best way to carry out measurements with severe gas evolution is a combination of (2) and (3), although they have their own drawbacks. 

Because most solutions absorb infrared radiation in their bulk, the design of the electrochemical cell is an important consideration in interfacial reflection experiments. The optimum configuration involves a very thin solution layer which is a few microns thick and is sandwiched between the optical window and the reflective electrode (fig. 10.8). In order to achieve maximum sensitivity, the window has a hemispherical or triangular (prism) shape. Nevertheless, most radiation is absorbed in the bulk of the solution and the effect of interfacially adsorbed molecules cannot be seen unless special steps are taken. One procedure is to polarize the light in a cyclical fashion between s- and p-polarized light. If adsorbate molecules interact with the p-polarized light, the intensity of the... 

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