The Universal Attenuated Total Reflectance Accessory (UATR) is an internal reflection accessory, used with the PerkinElmer FTIR systems, for simplifying the analysis of solids, powders, pastes, gels and liquids. The technique is a non-destructive. As the beam does not penetrate too far into the sample, this technique is ideal for analyzing strong infrared absorbing solutions, such as emulsions or aqueous solutions. The technique can also prove useful in measuring homogenous solid samples, solid surfaces and coatings on solid samples.
How the UATR works:
The technique involves placing a sample on top of a crystal with a high refractive index. An infrared
beam from the instrument is passed into the accessory and up into the crystal. It is then reflected
internally in the crystal, and back towards the detector which is housed in the instrument. When the
beam is reflected within the crystal, it penetrates into the sample by a few microns. Figure 2 illustrates
this process.
