Plasmon - Polaritons - Polarons - Excitons

Plasmon

Plasma is a quantum of plasma oscillation. This oscillation in a metal is a collective longitudinal excitation of the conduction electron gas. We pass an electron through a thin metallic film, and it will excite a Plasmon. The charge of the electron couples with the electrostatic field fluctuations of the plasma oscillations. The energy of Plasmon is equal to the integral multiple of reflected electron loss of energy. The plasma energies are calculated based on four valence electrons per atom.

Polaritons

The quantum of the coupled phonon-phonon transverse wave field is called a polaritons. Longitudinal phonons do not couple to transverse photons in the bulk of a crystal.

Polarons

In an insulator, the combination of the electron and its strain field is known as a polaron. A more subtle effect of electron-phonon interaction is the apparent increase in electron mass that occurs in polarons.

Excitons

We know that electrons and holes. The bound electron-hole pair is called an exciton. Excitons can be formed in insulating crystals.  An exciton can move through the crystal and transport energy. The absorption of photons is the creation of a bound electron-hole pair. All excitons are unstable concerning the recombination process. Excitons can form complexes, for instance, biexciton from two excitons.