Plasmon

Plasmons are called the quantized variations in the charge carrier density in semiconductors, metals and insulators; quantum mechanically they are treated as quasiparticles. The term is a common abbreviation for plasma oscillation quanta. Which is the photon of electromagnetic waves, the plasmon oscillations for the Fermi metals.

We distinguish:

• Particle plasmon
• Surface plasmon
• Volume plasmon

The first two belong to the plasmon - polaritons, since the electron density fluctuations couple with electromagnetic fields outside of the metal. Strictly speaking, surface and particle plasmons thus obtain the additional polariton.

Explanation

Classically, one can imagine plasmons as electrons oscillate relative to the positive ions.

To better illustrate, one can imagine a cubic metal block in a field pointing to the right. The free electrons are now moving to the left until the field is balanced inside. In this case, positive ions are exposed to the right. If you switch the external field from now, the electrons due to the mutual repulsion and attraction by the positive ions to the right. Thus, the electrons now oscillate at the plasma frequency back and forth until the energy is consumed by friction or other losses. Plasmons are the quantization of the self-oscillation.

Energy

Plasmons have approximately the energy

It is

• The Planck constant and
• The plasma frequency
• The density of the valence
• The elementary charge
• The electron mass
• The permittivity of vacuum.

• Quasiparticles