EXTERNAL REFLECTION FOURIER-TRANSFORM INFRARED-SPECTROSCOPY - THEORY AND EXPERIMENTAL PROBLEMS

In the reflection mode of spectroscopic measurements, IR radiation impinges on the surface of a sample and the intensity of the specularly reflected light is recorded. This is an easy to use, non-contact and non-destructive sampling technique suitable for samples with flat and smooth surfaces. The spectra obtained via external reflection depend on a number of factors and differ considerably from standard transmission spectra. These differences are explained and experimental factors that affect the nature of external reflection spectra are discussed.