PerkinElmer Spotlight 200, User Manual, Page: 111 / 132

Techniques for Collecting Spectra . 111
The greatest limitation to this method is the presence of an interfering diffuse reflection
signal. This occurs when the sample surface is not perfectly smooth. The Kramers–Kronig
integration is not appropriate for spectra from such samples.
Reflection-Absorption
Reflection-absorption occurs when the incident radiation passes through a thin, absorbent film
that is on a reflective surface (typically a metal) and is then reflected back through the film
(see Figure 43). The absorbance spectrum of the film can be collected directly. Figure 46
shows the spectrum of residual oil on an electronic contact. The sample diameter was 100 µm.
Figure 46 Reflection-Absorption Spectrum of Residual Oil on an Electronic Contact