Internal reflection spectroscopy description

And it was in 1967 that a detailed review and description of the state of the art of internal reflection spectroscopy was given in a short form by Hirschfeld and Wilks (18) and more comprehensively in the well known book of Harrick (19). In the following years up till now there were many papers on this topic, but with very few exceptions (which will be mentioned later) all of them deal with applications in the infrared region. 

The biggest changes that have occurred in recent years have been in instrumentation, and the chapter on IR experimental techniques has been revised extensively. We have avoided detailed descriptions of instruments rather we have described in broad terms the basic features of instrumentation. These include discussions of interferometers that are used in Fourier transform IR spectrometers, and discussions of grating monochromators that are used in dispersive IR spectrometers. Infrared spectra can be run on gases, liquids, or solids most of the techniques used in running these samples are discussed. Solid sampling techniques are the most diversified. Sections are included on quantitative analysis, internal reflection spectroscopy, and the use of polarized IR radiation. 

Electromoduiated Infrared Spectroscopy. The form most widely in use is the electromoduiated attenuated-total-reflection-spectroscopy. This is the electromoduiated form of the multiple internal reflection spectroscopy that was previously discussed. The practice here is to modulate, by switching the potential between two values, and monitor the absorption changes by lock-in techniques. Description of this technique with an emphasis on metal-electrolyte interfaces can be found in (70). The modulation here is different from all the other techniques that were mentioned in the sense that the modulation is not a small perturbation of an equilibrium state but a shift between two equilibrium states. Whether... 

Numerous books cover the topic of sampling methods in infrared spectroscopy (see, e.g., references [10-12]), and a detailed description of all the various alternatives is beyond the scope of this chapter. Instead, we will focus on the two sampling methods that are most commonly employed in food analysis applications, namely, the use of transmission cells for recording the spectra of solutions and the total internal reflection technique, also known as attenuated total reflectance (ATR). Readers who wish to learn about the techniques not covered here may consult the references cited above. 

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