8 . Spectrum Two HATR User's Guide
Introduction
The Horizontal Attenuated Total Reflectance (HATR) Accessory is an internal reflection
accessory used for simplifying the analysis of solids, powders, pastes, gels and liquids
(Figure 1). The technique is non-destructive.
Figure 1 The Horizontal Attenuated Total Reflectance (HATR) Accessory
As the beam does not penetrate 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 it 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 along the crystal, and back towards the detector that is housed
within the spectrometer. Each time the beam is reflected within the crystal, it penetrates into
the sample by a few microns. Figure 2 illustrates this process.
Figure 2 Principle of HATR operation
