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    When an incident electron collides with an orbital electron it becomes excited, that if there was enough energy. But if this energy is higher than the energy needed to excite the electron does it still get excited, as the absorption of photon on electrons stars that the photon has to be the exact amount of energy for an electron to be excited, no lower or higher value causes the electrons to be exited in photon absorption, is this the case with collision of electrons?


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    Anyone?


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    (Original post by Jimmy20002012)
    When an incident electron collides with an orbital electron it becomes excited, that if there was enough energy. But if this energy is higher than the energy needed to excite the electron does it still get excited, as the absorption of photon on electrons stars that the photon has to be the exact amount of energy for an electron to be excited, no lower or higher value causes the electrons to be exited in photon absorption, is this the case with collision of electrons?


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    No, electrons can collide with an atom and give up part of their energy in exciting an orbital electron. The remaining energy (kinetic) is kept by the electron. It can then go on to strike another atom and excite more orbital electrons. This is how an electron can lose its energy when it travels through materials. It makes a number of collisions with molecules/atoms and loses its energy gradually.

    The case of a photon colliding with an atom is more complicated. In one scenario the photon gives up all its energy to the orbital electron and then vanishes. In this case the photon needs exactly the right amount of energy to excite the electron.
    It is possible (though this is not studied at A Level) for a photon to give up only part of its energy in a collision with an atom. In this case the photon's frequency (and wavelength) is changed, as photon energy = hf
    Look up "Compton Effect", or "Compton Scattering".
    http://hyperphysics.phy-astr.gsu.edu.../comptint.html
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    (Original post by Jimmy20002012)
    When an incident electron collides with an orbital electron it becomes excited, that if there was enough energy. But if this energy is higher than the energy needed to excite the electron does it still get excited, as the absorption of photon on electrons stars that the photon has to be the exact amount of energy for an electron to be excited, no lower or higher value causes the electrons to be exited in photon absorption, is this the case with collision of electrons?


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    Basic conservation of energy. It will get excited and like the previous post said gain kinetic energy.
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    (Original post by Stonebridge)
    No, electrons can collide with an atom and give up part of their energy in exciting an orbital electron. The remaining energy (kinetic) is kept by the electron. It can then go on to strike another atom and excite more orbital electrons. This is how an electron can lose its energy when it travels through materials. It makes a number of collisions with molecules/atoms and loses its energy gradually.

    The case of a photon colliding with an atom is more complicated. In one scenario the photon gives up all its energy to the orbital electron and then vanishes. In this case the photon needs exactly the right amount of energy to excite the electron.
    It is possible (though this is not studied at A Level) for a photon to give up only part of its energy in a collision with an atom. In this case the photon's frequency (and wavelength) is changed, as photon energy = hf
    Look up "Compton Effect", or "Compton Scattering".
    http://hyperphysics.phy-astr.gsu.edu.../comptint.html
    Okay just to clarify, when an electron is incident on an orbital electron it gives it energy of hf, so the electron is excited and moves up to a higher energy level, if this energy is sufficient enough it can cause ionization where the orbital electron will be released from the atom.

    With photon absorption, where photons depends on frequency as this provides energy according to the equation of E=hf. There is a one to one interaction between an photon and the electron. The photon must have the exact amount of energy in order to excite the electron, thus the photon must be the same as the intial and final energy difference of the electrons. All of the electrons absorb the energy of hf, and these electrons occupy discrete energy levels


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    (Original post by Jimmy20002012)
    Okay just to clarify, when an electron is incident on an orbital electron it gives it energy of hf, so the electron is excited and moves up to a higher energy level, if this energy is sufficient enough it can cause ionization where the orbital electron will be released from the atom.

    With photon absorption, where photons depends on frequency as this provides energy according to the equation of E=hf. There is a one to one interaction between an photon and the electron. The photon must have the exact amount of energy in order to excite the electron, thus the photon must be the same as the intial and final energy difference of the electrons. All of the electrons absorb the energy of hf, and these electrons occupy discrete energy levels


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    First paragraph.
    No need for hf
    That's the energy of a photon, not an electron in this case.

    Otherwise ok.

    Para 2
    E=hf for photon is correct here.
    Yes the photon has to give up all its energy in this case so it must have energy equal to the exact difference of energy between the electron's initial and final energy level.
 
 
 
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