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Do electrons need specific energies to excite electrons

  1. May 12, 2013 #1
    Photons need specific energy levels, equal to the difference between two energy levels to excite an electron in an atom. Is this the same case with electrons that collide with atoms?
  2. jcsd
  3. May 13, 2013 #2

    Simon Bridge

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    Atomic energy levels are quantized.
    For a scattered electron to leave an atom in an excited state, then it must have given up a particular amount of energy. You want to know if some electron energies are particularly likely to leave an atom in an excited state.

    You want to investigate electron scattering spectra.

    Note: photons are absorbed by the atom - leaving it in an excited state.
    If an electron were absorbed into the atom, it would have to enter a particular orbital - incedentally turning your atom into an ion.
    In that context, your question is asking if some incoming electron energies are particularly likely to get the electron captured.

    This would come under electron absorbtion spectra.
  4. May 13, 2013 #3
    As Simon points out, only certain energies are allowed....electron energies in an atom are quantized....and remain so.....so in that sense yes.

    What is different is that while photons are electrically neutral, electrons are not....so electromagnetic repulsion plays a role in behavior.
  5. May 13, 2013 #4


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    When an electron collides with an atom, it can induce an energy-level transition by giving up an amount of kinetic energy that corresponds to that particular transition. It can then continue on its way with a reduced amount of kinetic energy.

    See for example the Franck-Hertz experiment.
  6. May 14, 2013 #5
    Incoming electron is only required to carry a K.E. which is larger than the difference in energy levels but not required to be a specific amount. As it can give out part of its energy to the atom, unlike photon which can give either all its energy or nothing.
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