4. Localized surface plasmons

In this section, without going into detail, we introduce localized surface plasmons and their various characteristics.

When the metal's dimensions are much smaller than the incident wavelength, the symmetry of the resonant electron cloud differs significantly from the classical case. This gives rise to another type of plasmon, localised surface plasmon resonance (LSPR). In the case of a metal nanosphere, electrons on the surface of the particle can oscillate in phase when excited by an incident electromagnetic wave, as illustrated in figure