Plasmon

Japanese: plasmon

…When the constituent particles follow Fermi statistics, two fermions are involved. Examples include plasmons caused by changes in the density of charges in a charged particle system, zero sound waves caused by changes in density in a system without a charge such as ^3He , and excitons, which are bound states of electrons and holes found in semiconductors. In the case of excitons, the situation in which the density is increased, i.e., a system of high-density excitons, can be approximately considered as a collection of bosons. …

From [Plasma Oscillation]

...In other words, the energy of plasma oscillations is not continuous, but is quantized into chunks of h ν _P ( h is Planck's constant). These chunks are considered as a kind of particle and are called plasmons. When a high-speed electron beam passes through a metal film, the generation of plasmons can be observed. ...

*Some of the terminology explanations that mention "plasmon" are listed below.

Source | Heibonsha World Encyclopedia 2nd Edition | Information

Japanese:

…構成粒子がフェルミ統計に従う場合は，2個のフェルミ粒子が関与している。例としては，荷電粒子系での電荷の密度の変化に伴うプラズモンplasmon,³Heのように電荷をもたない系での密度変化によるゼロ音波，半導体中などで見られる電子と正孔の束縛状態としての励起子などがある。なお，励起子の場合，その密度を高くした状況，すなわち，高密度励起子の系は，近似的にボース粒子の集団とみなせる。…