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What are plasmons?
A plasmon is a quantum of plasma oscillation, just like photon is a quantum of light radiation.
Plasmon is a quasiparticle resulting from the quantization of plasma oscillations.
Plasmons play a large role in the optical properties of metals. Light of frequency below the plasma frequency is reflected, because the electrons in the metal screen the electric field of the light. Light of frequency above the plasma frequency is transmitted, because the electrons cannot respond fast enough to screen it. In most metals, the plasma frequency is in the ultraviolet, making them shiny (reflective) in the visible range.
[gview file=”http://www.photonics.ethz.ch/fileadmin/user_upload/optics/Courses/NanoOptics/plasmons.pdf”]
Surface plasmons
Surface plasmons are those plasmons that are confined to surfaces and that interact strongly with light resulting in a polariton
Read more at http://en.wikipedia.org/wiki/Surface_plasmon
[gview file=”http://www.optics.rochester.edu/workgroups/novotny/courses/OPT463/plasmonss.pdf”]
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Current Carriers and conduction
1. Do the protons flow when current flow?
2. In case of semiconductor do the holes flow?
Animesh asked
Answer:
In metallic conductors, free electrons are the current carriers, i.e, it is due to the motion of the free electrons that conduction takes place in a metallic conductor. The protons do not move as they are inside the nucleus and bound by strong nuclear forces. It is the electrons of the outermost shell of the atom which are least bound to the atom, flow and cause conduction
In semiconductors the current carriers are free electrons and holes.
What are holes?
Holes are actually vacancies created when an electron is freed from a bond. It is assigned a positive charge. When a potential difference is applied across a semiconductor, the free electrons move towards the positive terminal as in the case of a metal. The bonded electrons also move towards positive terminal from vacancy to vacancy and this causes the holes t move towards the negative terminal.
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