Thomson scattering

(noun)

an elastic scattering of electromagnetic radiation by a free charged particle, as described by classical electromagnetism. It is just the low-energy limit of Compton scattering

Related Terms

Examples of Thomson scattering in the following topics:

  • The Compton Effect

    • Compton scattering is an inelastic scattering of a photon by a free charged particle (usually an electron).
    • Part of the energy of the photon is transferred to the scattering electron.
    • Compton scattering is an example of inelastic scattering because the wavelength of the scattered light is different from the incident radiation.
    • Although nuclear Compton scattering exists, Compton scattering usually refers to the interaction involving only the electrons of an atom.
    • Thomson scattering, the classical theory of an electromagnetic wave scattered by charged particles, cannot explain low intensity shifts in wavelength: classically, light of sufficient intensity for the electric field to accelerate a charged particle to a relativistic speed will cause radiation-pressure recoil and an associated Doppler shift of the scattered light.

  • Thomson Scattering

    • So far we have examined the scattering of polarized radiation.
    • It is straightforward to think about scattering of unpolarized radiation by taking the incoming beam to be a sum of two beams whose polarization differs by $\pi/2$.
    • More energy is scattered into the ${\bf E}_{w,1}-{\bf n}$ plane than in the other in the ratio of $1:\cos^2 \theta$, so the scattered radiation is polarized with

  • Cherenkov Radiation

  • Relativistic Bremsstrahlung

    • We can imagine that the second charge Thomson scatters some of this "virtual'' wave to form a real wave.
    • We need to calculate the Fourier transform of this virtual wave to get the spectrum of scattered radiation
    • It's quite straightforward to calculate the flux of virtual radiation scattered by the electron,
    • The extra bit with $\sigma(\omega)/\sigma_T$ is to include the fact that the cross-section for electrons to scatter light differs from $\sigma_T$.
    • So bremsstrahlung comes down the Thomson scattering of the virtual photons of the electromagnetic field of an ion.

  • Diffraction Revisited

    • George Paget Thomson passed a beam of electrons through a thin metal film and observed the predicted interference patterns.
    • The periodic structure of a crystalline solid acts as a diffraction grating, scattering the electrons in a predictable manner.
    • They are scattered by the nuclei of the atoms, unlike X-rays, which are scattered by the electrons of the atoms. 
    • For example, the scattering of X-rays is highly dependent on the atomic number of the atoms (i.e., the number of electrons), whereas neutron scattering depends on the properties of the nuclei.
    • In addition, the magnetic moment of the neutron is non-zero, and can thus also be scattered by magnetic fields.

  • The Rutherford Model

    • Thomson's so-called "plum pudding model" of the atom was incorrect.
    • Measuring the pattern of scattered particles was expected to provide information about the distribution of charge within the atom.
    • Rutherford, Thomson, electrons, nuclei, and plums.

  • The Thomson Model

    • Thomson proposed that the atom is composed of electrons surrounded by a soup of positive charge to balance the electrons' negative charges.
    • In Thomson's model, the atom is composed of electrons (which Thomson still called "corpuscles," though G.
    • The 1904 Thomson model was disproved by the 1909 gold foil experiment performed by Hans Geiger and Ernest Marsden.
    • Intro to the History of Atomic Theory - The Thomson Model
    • Rutherford, Thomson, electrons, nuclei, and plums.

  • Scattering of Light by the Atmosphere

    • Rayleigh scattering describes the air's gas molecules scattering light as it enters the atmosphere; it also describes why the sky is blue.
    • Rayleigh scattering is the elastic scattering of waves by particles that are much smaller than the wavelengths of those waves.
    • Rayleigh scattering is due to the polarizability of an individual molecule.
    • So, the shorter the wavelength, the more it will get scattered.
    • When you look closer and closer to the sun, the light is not being scattered because it is approaching a 90-degree angle with the scattering particles.

  • Scattering

    • However, there is a big elephant in the middle of the room that we have been ignoring—bf scattering.
    • Why is scattering a problem?
    • We can first look at a process in which the photon is scattered into a random direction without a change in energy.
    • If isotropic scattering is the only process acting we find that the source function
    • Even if one neglects scattering, one often has to solve an integro-differential equation.

  • Polarization By Scattering and Reflecting

    • Unpolarized light can be polarized artificially, as well as by natural phenomenon like reflection and scattering.
    • Just as unpolarized light can be partially polarized by reflecting, it can also be polarized by scattering (also known as Rayleigh scattering; illustrated in ).
    • In all other directions, the light scattered by air will be partially polarized.
    • Also known as Rayleigh scattering.
    • Unpolarized light scattering from air molecules shakes their electrons perpendicular to the direction of the original ray.