Plasmon



In physics, the plasmon is the polariton.

Since plasmons are the quantization of classical plasma oscillations, most of their properties can be derived directly from Maxwell's Equations.

Explanation

Plasmons are explained in the classical picture using the electron gas is moving in a periodic potential of this ion grid.

Plasmons play a large role in the optical properties of metals. ultraviolet[1]. That is why they are reflective, too.

The plasmon energy can often be estimated in the free electron model as

E_{p} = \hbar \sqrt{\frac{n e^{2}}{m\epsilon_0}}

where n is the electron mass and ε0 the permittivity of free space.

Surface plasmons

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More recently surface plasmons have been used to control colours of materials[1]. This is possible since controlling the material's surface shape controls the types of surface plasmons that can couple to it and propagate across it. This in turn controls the interaction of light with the surface. These effects are illustrated by the historic stained glass which adorn medieval cathedrals. In this case, the color is given by metal nanoparticles of a fixed size which interacts with the optical field to give the glass its vibrant color. In modern science, these effects have been engineered for both visible light and microwave radiation. Much research goes on first in the microwave range because at this wavelength material surfaces can be produced mechanically as the patterns tend to be of the order a few centimeters. To produce optical range surface plasmon effects involves producing surfaces which have features <400 nm. This is much more difficult and has only recently become possible to do in any reliable or available way.

Possible applications

Plasmons have been considered as a means of transmitting information on computer chips, since plasmons can support much higher frequencies (into the 100 THz range, while conventional wires become very lossy in the tens of lithography and microscopy due to their extremely small wavelengths. Both of these applications have seen successful demonstrations in the lab environment. Finally, surface plasmons have the unique capacity to confine light to very small dimensions which could enable many new applications.

Surface plasmons are very sensitive to the properties of the materials on which they propagate. This has led to their use to measure the thickness of monolayers on protein binding events. Companies such as Biacore have commercialized instruments which operate on these principles. Optical surface plasmons are being investigated with a view to improve makeup by L’Oréal among others.[2]

See also

References

  • Stefan Maier (2007). Plasmonics: Fundamentals and Applications. Springer. ISBN 978-0387331508. 
  • Heinz Raether (1980). Excitation of plasmons and interband transitions by electrons. Springer-Verlag. ISBN 0-387-09677-9. 
  • A.V. Zayats, I.I. Smolyaninov, A.A. Maradudin, "Nano-optics of surface plasmon polaritons," Phys. Rep., vol. 408, pp. 131-314 (2005).
  • Harry A. Atwater (2007). The Promise of Plasmonics. In Scientific American, April 2007 v.296 n.4, pg.56-63
  1. ^ Kittel, C.: "Introduction to Solid State Physics", 8th edition, Wiley 2005, Table 2 on p. 403
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Polaron
 
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