- 3016 - PARTICLE PHYSICS - Phonons, Plasmons, and Magnons? Phonons, Plasmons, and Magnons, you probably have not heard of these. They are particles that appear in material when sizes are very small. When we get into the very, very small all particles are also waves. This is called a wave-particle duality in physics.
------------------- 3016 - PARTICLE PHYSICS - Phonons, Plasmons, and Magnons
- All mass has a corresponding wavelength. Even your mass has a wavelength. But, unless your mass is very small you will not notice the waves. The math for these waves is:
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------------------ wavelength = 2.25 * 10^-42 / mass , meters
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- From the formula you can see that wavelength varies inversely with mass. The larger the mass the smaller the wavelength. The smaller the mass the larger the wavelength. The mass of an electron inside an atom is 9 * 10^-31 kilograms.
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- Substituting this small mass into the equation and the wavelength is 2.5 * 10^-10 meters. 10^-10 meters, or 1/10 of a nanometer is about the size of the atom. So, the wavelength for an electron is the size of the atom.
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- Since all mass is energy, the math can also be expressed electron-volts:
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-------------------- wavelength = 1.044 * 10^-23 / mass, electron volts * seconds / meter
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- Again, the wavelengths have very low energy until the mass is very, very small. So, let’s get familiar with the small. Starting with a bacteria which is about 1,000 nanometers in size down to the size of the atomic nucleus: A nanometer is a billionth of a meter, it is 10^-9, or, 0.000,000,001 meters in size.
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--------------------- Bacteria ------------- 1,000 nanometers
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--------------------- Virus ------------- 100 nanometers
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--------------------- Protein Molecule ---- 10 nanometers
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--------------------- DNA strand ---------- 1 nanometers
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--------------------- Atom ----------------- 0.1 nanometers
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--------------------- Nucleus ----------------- 0.00001 nanometers
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- The atom at 1/10th of a nanometer is the diameter of the valence electrons orbiting the nucleus. The valence electrons are the outside electrons that conduct all the stuff in chemistry. The atom itself is mostly empty space with the nucleus only 1/10,000th the size of the atom sitting at the center.
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- Matter comes in gas, liquids, and solids. When we get to solids the atoms form in a lattice structure. The dimensions of the lattice are the size of the atoms. In one cubic centimeter, the size of a sugar cube, there are 10^23 atoms. A solid cubic centimeter has 10,000,000,000,000,000,000,000 atoms.
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- The atoms and all the fundamental particles that make up the atoms are both waves and particles at these dimensions. I will call them particles but remember, I would be equally accurate calling them waves.
- A “Phonon” is a quantized mode of vibrations occurring in the atomic lattice structure of atoms. It is a type of sound wave going through the solid material. It is a unique wave in that each part of the lattice structure oscillates at the same frequency.
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- These vibrations can be studied using either wave -mechanics or particle mechanics, both work. The math is called Quantum Mechanics and the particles are called Phonons.
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- “Plasmons” are quantum of plasma oscillations. Photons are quantums of light. Phonons are quantums of sound vibrations. Plasmons are similar but they occur in plasma, which is simply a soup of charged particles.
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- When nuclei lose their electrons they remain positively charged and are called “ions‘, or plasma. All metals are 3-dimensional crystals of positively charged ions, or nuclei. The electrons in metals are free to move between the ions and that is how metals conduct electricity and heat.
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- These Plasmons also have an interesting affect at the surface of the metal. Light striking the surface of a metal that has a frequency below the Plasmons frequency of vibration is reflected because the electrons in the metal screen out the electric field of the light.
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- In most metals the Plasmons frequency is in the range of ultraviolet frequencies. That is why most metals appear shiny in visible light. Metals are reflective of light.
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- Surface Plasmons have been used to control of colors of materials. Cathedral builders in the middle ages learned this without the tools of math or physics. Simply by observation they learned to design stained glass windows with glass in vibrant colors. The interaction of light with metal nanoparticles of fixed size, about 400 nanometers, interacts with visible light creating beautifully colored glass.
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- Today, physicists are studying Plasmons and hope to use them in computer chips. Due to their high frequency range in the 100 terahertz they could handle lots of data. They may be used in microscopy due to their extremely small wavelengths. They may be used in colloid films to identify protein molecules in a sample. They may show up in cosmetics for women’s makeup.
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- “Magnons” are quantum particles of magnetic moments. The intrinsic spin of every electron has associated with it a magnetic moment. Electrons are spin ½ fermions and have a 2 state magnetic moment of either spin-up or spin-down.
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- “Fermions” are the physics name for ordinary matter. Fermions all have ½ integer spins and include protons, neutrons, and electrons. In contrast, there is a category of force carrier particles that have integer spins called “Bosons“.
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- A photon is a Boson and the force carrier for the Electromagnetic Force. Fermions are made up of Quarks and Leptons. There are 6 types of Quarks and 6 types of Leptons, 12 fundamental particles of matter. Adding 12 particles of corresponding antimatter for 24 fundamental particles in all matter. Quarks make up protons and neutrons. Leptons include electrons, muons, and neutrinos.
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- By studying Magnons science is developing a new technology called Spintronics. By controlling the up and down spin of electrons engineers are developing new computer hard drives with devices called Giant Magnetoresistance (GMRs) and Tunnel Magnetoresistance (TMRs) to greatly increase data storage capacities.
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- MRAMs are magnetic random access memories that can store data with all the power off thus allowing instant-on computing. Another design is called a Racetrack memory that stores data on a ferromagnetic metal wire.
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- There are more of these particles that I will not go in to. Electron Holes are particles created by a missing valence electron. Engineers have been designing with these in semiconductors for a long time.
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- Exitons are bound electron and hole pairs.
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- Polarons are moving charges surrounded by ions.
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- Polaritons are a mixture of photons with these other quasi-particles. Most exciting is the study of these particles in Superconductivity. Superconductors carry electricity and magnetism with no resistance.
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- They are made at temperatures of absolute zero, near 0 Kelvin, however, using these new particles materials are being developed the work at 55 Kelvin, even 90 Kelvin. Room temperature is 300 Kelvin. If higher temperatures are achieved partical use of superconductors will arrive.
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February 2, 2021 PARTICLE PHYSICS - Phonons, Plasmons, 3016
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--------------------- --- Tuesday, February 2, 2021 ---------------------------
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