Particle plasmon

As particle plasmons or localized surface plasmons are called immovable surface plasmons , not propagating field increases on small metal particles such as gold or silver. It is therefore a special plasmon . For sufficiently small particles (diameter ≪ wavelength of the incoming electromagnetic radiation , e.g. light) such an electrostatic approximation can be viewed as an oscillating dipole . Its dipole moment is:

${\displaystyle p=4\pi \varepsilon _{0}\varepsilon _{\mathrm {m} }R^{3}{\frac {\varepsilon -\varepsilon _{\mathrm {m} }}{\varepsilon +2\varepsilon _{\mathrm {m} }}}.}$

Are there

• ${\displaystyle \varepsilon _{0}}$the permittivity of the vacuum
• ${\displaystyle \varepsilon _{\mathrm {m} }}$ the permittivity of the surrounding medium
• ${\displaystyle \varepsilon }$ the permittivity of the metal
• ${\displaystyle R}$ the radius of the metal ball.

Since the permittivity of metals depends very much on the wavelength of the electromagnetic oscillation ( Drude theory ), the size of the polarization is also dependent on the wavelength. Incoming light is thus absorbed and scattered by the dipole to different degrees for different frequencies . This effect is used on lead glass panes, which means that they take on different colors.

literature

Sönnichsen, Carsten: Plasmons in metal nanostructures. (pdf; 2.7 MB) In: Dissertation. June 20, 2001, accessed April 15, 2009 (Chapter 4).