Reststrahlen effect

The residual radiation effect of the reflection is a phenomenon of electromagnetic radiation in the boundary layers of dielectric materials. Here, an electromagnetic wave of low -energy range can not propagate in a medium into when manifested with the optical refractive index and an absorption band in the relevant medium. This band is called residual -ray band. Radiation in the rest -ray band is highly reflective to totally under normal incidence at the interface to this medium.

The residual radiation method that is based on this effect was developed in the late 19th century by Heinrich Rubens. For frequencies in the far-infrared spectrum ( in the terahertz range ) for the first time could be isolated.

Appearance

Many physical properties of a material affect on the look of the rest -ray bands, including phonon band gaps, particle or grain sizes and strongly absorbing components or components with bands of high absorption, such as in the infrared range. Therefore, residual radiation belts manifest, for example, in almost all spectra of infrared spectroscopy. To show diffusely reflecting surfaces in the absorption spectrum of a completely inverted band. Wherein the infrared emission spectroscopy, however, shows an emission minimum.

Application

The residual radiation effect is used to determine the properties of semiconductors. It also comes in geophysics and meteorology for use. Another new application of the effect is to find buried land mines from a distance.