Explaining Surface Plasmon Excitation by Light

  • Thread starter geo_alchemist
  • Start date
  • Tags
    Surface
In summary, surface plasmons are generated when light with a normal component to the surface is incident on a material with high conductivity. This condition is necessary due to the conservation of momentum and the different boundary conditions for electric fields parallel and normal to the surface. The electric field parallel to the surface is small due to the high mobility of charges, while the electric field normal to the surface is hindered and can build up outside the metal.
  • #1
geo_alchemist
35
0
Surface Plasmons ?

Well, to begin with, I am not a physicist and therefore please don't redirect me to some physics tutorials.
now the question:
Why is it necessary for surface plasmon exitation by light that the incident light must have component normal to the surface?
I know that this condition can be fulfilled only in case of p-polarized light. but my questioin is about necessity of normal component.
Pls, if anyone can explain this to me, I would be much obliged.
 
Physics news on Phys.org
  • #2


Isn't it just conservation of momentum?
If you want plasmons to be generated to the left of a surface then the light coming in from the right must reflect to the right.
 
  • #3


Sorry, I can't follow the point.
may be for you it looks as A, B, C, but for me it's far more complex.
can you tell me in more details, what you mean by "If you want plasmons to be generated to the left of a surface then the light coming in from the right must reflect to the right"?
 
  • #4


Inside the metal, all electric fields are very small, as conductivity is high. Now from the Maxwell equations there arise two different boundary conditions for the electric field parallel and normal to the surface. The electric field component parallel to the surface has to be continuous, while normal to the surface, D has to be continuous. Now even if E normal to the surface inside the metal is small, D=E*epsilon is much larger as the absolute value of epsilon is high (roughly equal to the conductivity of the metal).
Roughly speaking, the electric field parallel to the surface approximately vanishes due to the high mobility of the charges parallel to the surface. In direction normal to the surface, the mobility of the charges is hindered (by the surface) so that higher fields can build up, at least outside the metal.
 

1. What is surface plasmon excitation?

Surface plasmon excitation is a phenomenon that occurs when light interacts with a metal surface, causing the electrons in the metal to oscillate and create a collective electron wave known as a surface plasmon.

2. How does light excite surface plasmons?

Light excites surface plasmons by matching its energy and momentum with those of the surface plasmons. This can be achieved through various methods such as using a prism to couple light into a metal film or using a grating to create a periodic structure on the metal surface.

3. What is the significance of surface plasmon excitation?

Surface plasmon excitation has many practical applications, such as enhancing the sensitivity of biosensors, improving the efficiency of solar cells, and enabling subwavelength optical imaging.

4. How is surface plasmon excitation related to nanotechnology?

Surface plasmon excitation plays a crucial role in nanotechnology by allowing for the manipulation and control of light at the nanoscale. This has led to advancements in fields such as nanophotonics, plasmonic devices, and surface-enhanced spectroscopies.

5. Can surface plasmon excitation be observed in other materials besides metals?

While surface plasmon excitation is most commonly observed in metals, it can also occur in other materials such as semiconductors and graphene. These materials have different properties that can lead to unique surface plasmon behaviors and potential applications.

Similar threads

  • Advanced Physics Homework Help
Replies
1
Views
2K
  • Atomic and Condensed Matter
Replies
2
Views
3K
Replies
1
Views
3K
  • Sci-Fi Writing and World Building
Replies
1
Views
426
  • Introductory Physics Homework Help
Replies
25
Views
2K
  • Electromagnetism
Replies
4
Views
851
  • Advanced Physics Homework Help
Replies
1
Views
3K
  • Introductory Physics Homework Help
Replies
16
Views
3K
Back
Top