plasmon resonance (rus. плазмонный резонанс) — excitation of a surface plasmon at its resonance frequency by an external electromagnetic wave (for nanometer-sized metallic structures, the phenomenon is called localisised plasmon resonance).

Description

The technique that facilitates the use of surface plasmons in optical applications which is based on the phenomenon of total internal reflection. In the event of total internal reflection, an electromagnetic wave spreads along the reflecting surface, and the speed of the wave depends on the incidence angle. If at a certain incidence angle the speed of the wave matches the speed of a surface plasmon on the surface of the metal, the conditions required for total internal reflection will no longer exist, and the reflection will no longer be total, causing surface plasmon resonance.

Modification of collective electron excitations occurs in nanoscale metallic systems. The collective electron excitation of metal nanoparticles sized smaller than the wavelength of electromagnetic radiation in the surrounding environment (localisised surface plasmon) oscillates at a frequency that is √3 times smaller than the frequency of a bulk plasmon, while the frequency of a surface plasmon is approximately √2 times smaller than the frequency of a bulk plasmon. A resonance occurs when the frequency of the external field matches the frequency of localisised surface plasmon, causing an abrupt amplification of the field on the particle surface and the growth of absorption cross-section.

The properties of localisised plasmons are in critical dependence on the shape of nanoparticles, which makes it possible to tune the system of their resonances for an effective interaction with light or basic quantum systems.

Today, surface plasmon resonance is widely used in the creation of chemical and biological sensors (biosensors). Plasmon effects engaging with biological objects (DNA, viruses, and antibodies) help increase intensity of fluorescence signals by more than an order of magnitude, which enables a better detection, identification and diagnostics of biological objects.

Author

  • Naymushina Daria A.

Sources

  1. Perlin E.Ju et al Solid State Physics. Optics of semiconductors, dielectrics and metals: A Tutorial. — SPB.: SPBGU ITMO, 2008. — 216 p.
  2. Pompa P. P., Martiradonna L. et al. Metal-enhanced fluorescence of colloidal nanocrystals with nanoscale control // Nature Nanotechnology. 2006. V. 1. P. 126–130.

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