Localized plasmon and bulk plasmon on a nanoparticle

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In summary: This phenomenon can occur even in the quasistatic approximation, where the electric field is uniform on the nanoparticle surface.
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As far as I have understood, surface plasmon can't be excited with natural light because the dispersion relation of the plasmon doesn't cross the vacuum dispersion relation of light.

But, when we decrease the size (for example, we take a nanoparticle), we are now in quasistatic approximation. Thus, the electric field is uniform in the sphere and we don't have plasmon propagation on the surface. Instead, we have a localised excitation.

Surface plasmon (wave propagation inside) :
26552706_10213757820600271_578098450_n.png

Localised surface plasmon (no propagation because electric field is uniform on the sphere)

26234458_10213757811520044_584343951_n.png


But then, what I don't understand is that for me we then should only have localized surface plasmon in nanoparticle. As bulk plasmon result of wave propagation and because we are in quasistatic approximation (electric field vary in time but uniform on the sphere), such modes can't occur for nanoparticle.

But in an article I'm reading it seems like it is possible to have bulk excitation in nanoparticles, so I'm very confused...

Here is the link for the article : doi:10.1038/nature10904My question : what does that mean to have bulk plasmon for nanoparticle ? As the quasistatic approximation is true such modes should'nt exist ?
 

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From what I understand, the article you linked talks about the fact that it is possible to excite bulk plasmons in nanoparticles, but not in the traditional sense. Instead of having a propagating wave on the surface, the bulk plasmon excitation is localized to the surface, and the plasmon fields decay exponentially with distance from the nanoparticle. The electric field is still uniform over the entire nanoparticle, but the field strength of the plasmon decreases exponentially with distance from the nanoparticle surface. This is why they call it "localized bulk plasmons".
 

What is the difference between localized plasmon and bulk plasmon on a nanoparticle?

Localized plasmon refers to the collective oscillation of free electrons in a metal nanoparticle that is confined to a specific region, resulting in a localized electromagnetic field. In contrast, bulk plasmon refers to the collective oscillation of free electrons in a bulk metal material, which extends throughout the entire material.

How do localized plasmon and bulk plasmon affect the optical properties of a nanoparticle?

The presence of localized plasmon and bulk plasmon on a nanoparticle can greatly enhance its optical properties, such as scattering and absorption. This is because the collective oscillation of free electrons produces a strong electromagnetic field, which can interact with light and modify its behavior.

What factors influence the strength of localized plasmon and bulk plasmon on a nanoparticle?

The strength of localized plasmon and bulk plasmon on a nanoparticle is influenced by several factors, including the size, shape, and material of the nanoparticle, as well as the surrounding dielectric medium and the incident light wavelength.

What are some applications of localized plasmon and bulk plasmon on nanoparticles?

Localized plasmon and bulk plasmon on nanoparticles have numerous applications in areas such as sensing, imaging, and photothermal therapy. They can also be used in plasmonic devices for manipulating light at the nanoscale.

How can localized plasmon and bulk plasmon be controlled and tuned on a nanoparticle?

The properties of localized plasmon and bulk plasmon on nanoparticles can be controlled and tuned by changing the size, shape, and material of the nanoparticle. Additionally, the surrounding dielectric medium and the incident light wavelength can also be adjusted to manipulate the plasmon behavior.

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