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Does the nucleus of atoms of noble gases vibrate and emit E.M wave

  1. Oct 20, 2013 #1
    People normally talk of electrons performing oscillatory motion when an electromagnetic field is incident on an atom.

    But, won't the electric field of the E.M. wave cause the nucleus of the atom to vibrate...???
    . "Note: Here I am talking of isolated atoms, that is atoms of noble gases, and not of molecules."

    Please don't explain me the infrared absorption of light by molecules like CO2.

    I understand that nucleus' mass is very high compared to electrons but even then won't it vibrate, with a very small amplitude or frequency...???

    And if the the nucleus vibrates then we must think that vibrating positive charge of the nucleus will re-emit the radiation in all directions according to principles of electrodynamics.

    But I have never heard of people talking of re-emission of electromagnetic radiation from nucleus. "People only talk of when a non-resonant light wave impinges upon an atom,it sets electrons of atoms vibrating and consequently they(electrons) re-emit this energy in the form of E.M. radiation in all direction according to a principle of electrodynamics." .

    No one talks of re-emission of E.M. wave from a vibrating nucleus,oscillating with a much less amplitude than electrons...................

    Why Why Why:confused:
  2. jcsd
  3. Oct 20, 2013 #2


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    Staff: Mentor

    An isolated nucleus will scatter electromagnetic waves just as electrons do.
    If you have a neutral atom, on the other hand, the contributions from electrons dominate and cancel the effect from the nucleus - unless you hit specific resonance frequencies. of the nucleus.
  4. Oct 20, 2013 #3

    Jano L.

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    Yes, in principle. In practice, as mfb says, about interaction of EM wave with the nuclei makes sense only for resonance frequencies of nuclei when the electrons react negligibly. That probably happens in the NMR experiments, but then people from this field do not usually talk about nuclei vibrating, but rather talk about their magnetic moment rotating and about spin flipping.
  5. Oct 20, 2013 #4


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    Staff: Mentor

    Strictly speaking, it is the nucleus-electron system that is reacting to EM radiation and "vibrating". It is just that the mass ratio between the electron and the nucleus is such that there is not much difference between considering the relative motion and considering the nucleus as infinitely heavy and just looking at the motion of the electron.
  6. Oct 21, 2013 #5
    Thanks to all for replies...!!!
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