Residual rays effect

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The residual radiation effect is a phenomenon of the reflection of electromagnetic radiation at boundary layers of dielectric materials. An electromagnetic wave with a low energetic bandwidth cannot propagate into a medium if the optical refractive index also manifests an absorption band in the medium in question. This band is called the residual ray band. Radiation in the residual radiation band is strongly or totally reflected at the interface with this medium under perpendicular incidence.

The residual radiation method based on this effect was developed by Heinrich Rubens at the end of the 19th century . This enabled frequencies in the far infrared spectrum (in the terahertz range) to be isolated for the first time.

Appearance

Numerous physical properties of a material have an influence on the appearance of the residual radiation band, including phonon band gaps, particle or grain sizes as well as highly absorbent components or components with bands of high absorption, e.g. B. in the infrared range . Therefore, residual radiation bands manifest themselves, for example, in almost all spectra of infrared spectroscopy . Diffuse reflecting surfaces show a completely inverted band in the absorption spectrum. In the case of infrared emission spectroscopy, however, there is an emission minimum.

application

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

literature

  • Charles Elachi, Jakob Van Zyl: Introduction to the Physics and Techniques of Remote Sensing . 2nd Edition. John Wiley & Sons, 2006, ISBN 0-471-47569-6 .

Web links

  • Residual rays . In: Meyers Großes Konversations-Lexikon . tape 16 , 1908, pp. 826 ( zeno.org [accessed February 20, 2018]).
  • Heinz-Wilhelm Hübers: Terahertz waves. In: World of Physics. January 29, 2009 . ;(including via terahertz radiation and residual radiation method).

Individual evidence

  1. ↑ Marianus Czerny: About a new form of Rubens' residual radiation method . In: Journal of Physics . tape 16 , 1923, pp. 321-331 , doi : 10.1007 / BF01327403 .
  2. ↑ Mark S. Anderson, Jason M. Andringa, Robert W. Carlson, Pamela Conrad, Wayne Hartford, Michael Shafer, Alejandro Soto, Alexandre I. Tsapin, Jens Peter Dybwad, Winthrop Wadsworth, Kevin Hand: Fourier transform infrared spectroscopy for Mars science . In: Review of Scientific Instruments . tape 76 , no. 3 , 2005, p. 034101 , doi : 10.1063 / 1.1867012 .
  3. ^ Arnold Goldberg, Parvez N. Uppal, Michael Winn: Detection of buried land mines using a dual-band LWIR / LWIR QWIP focal plane array . In: Infrared Physics & Technology . tape 44 , no. 5-6 , pp. 427-437 , doi : 10.1016 / S1350-4495 (03) 00174-9 .