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Homework Help: Difference between photon and electron collisions with atoms

  1. Jun 13, 2010 #1
    Hi,

    Would anyone be able to explain the main differences between the effect of electrons and photons colliding with atoms in the ground state.

    As far as I understand they are very similar as both cause excitation and in some cases ionization.

    Any help would be greatly appreciated.

    Dave
     
  2. jcsd
  3. Jun 14, 2010 #2
    One difference is that the electron is charged while the photon is not. So the photon will collide with the atom based solely on its energy, while the electron will interact electromagnetically with the electrons.

    In addition, a photon can be completely absorbed while an electron cannot.
     
  4. Jun 14, 2010 #3
    The photon could collide with an electron from the atom as described in the Compton effect, pushing the electron a little. The photon will loose some of its energy (therefore frequency as well) and fly off in another direction. An electron could bump into another electron as described as well, but they would not collide like you would think of two marbles, but rather electromagnetically, like dulrich already said.

    But both can exite an atom, which might later emit a photon and glow. The electron collision resulting in light is something one finds in an x-ray cathode, or a regular gas lamp like a neon sign. The photon collision resulting in light would be all flouroscense, like one has in these bright colors and most glow-in-the-dark stuff as well.
     
  5. Jun 14, 2010 #4
    Brilliant, thank you both for your help!
     
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