Infrared and IR-ATR spectroscopy

Conventionally, infrared spectroscopy is carried out in the transmission mode, where the light passes through a sample cell with a defined thickness. There are two main disadvantages of this technique for the purpose of reaction analysis. 

A general solution to both problems is the application of attenuated total reflectance (ATR) in combination with infrared spectroscopy. The theory of ATR spectroscopy is well described in several books and articles which also demonstrate the applicability of the Beer-Lambert law to ATR spectroscopy [9]. The combination of reaction calorimetry and ATR spectroscopy is now rather common [ 10-13] typically using commercially available calorimeters. 

The technique of IR-ATR spectroscopy is easy to apply in reaction analysis as no sampling or flow-through cells are required. As most organic compounds are infrared-active, the technique is useful for many reaction types. However, there are some matters that should always be kept in mind when the reaction s IR-ATR spectrum is interpreted. 

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