As a result of this inability to propagate, normally incident Reststrahlen band radiation experiences strong-reflection or total-reflection from that medium.
Numerous physical attributes of a compound will have an effect on the appearance of the Reststrahlen band.
The term Reststrahlen was coined following the observation by Heinrich Rubens in 1898 that repeated reflection of an infrared beam at the surface of a given material suppresses radiation at all wavelengths except for certain spectral intervals, and Rubens detected wavelengths of sizes around 60 μm.
Obviously, this contrast increases with the number of reflections and explains the observation made by Rubens and the term Reststrahlen (residual rays) used to describe this spectral selection.
[2] Reststrahlen bands manifest in diffuse reflectance infrared absorption spectra as complete band reversal, or in infrared emission spectra as a minimum in emissivity.