This program simulates the scattering of light off of an electron, the Compton effect. Compton used the idea that light behaves like a particle to explain light-electron (photon-electron) scattering. He used the relation for the energy and momentum of the photon:, E = hf and p = E/c or p = h/λ, and the relativistic expression for the energy of the electron, E = (mc2 = (p2c2 + m2 c4)1/2, and applied relativistic energy and momentum conservation for the collision. The wavelength shift of the light depend on the angle of the scattered photon (and the electron)? Observe the change in wavelength of the light. It is given by λ' - λ = (h/mc)[1-cos(θ)], where λ' is the scattered photon's wavelength and θ is the photon's scattering angle.
By changing the scattering angle, θ, which is shown as "a" in the simulation, the angle of the scattered photon changes according to Compton's equation. The panel on the left shows the experimental set up, while the panel on the right shows the resulting photon wavelength from the scattering. In a typical Compton experiment, light is scattered off of the electrons in an atom, and there is little scattering due to the more tightly held electrons while there is more scattering due to the less tightly held electrons. This is what is responsible for the two peak distribution shown.
This simulation is part of a suite of simulations by Jose Ignacio Fernández Palop of the University of Cordoba, Spain used to teach quantum mechanics. Additional simulations can be found on the OSP ComPADRE site.
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