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Excitation, ionization, TEMPERATURE?

  1. Jun 27, 2004 #1
    excitation, ionization, TEMPERATURE??

    When atomic electrons are excited or ionized, do they contribute to temparature rise??
    If yes, what energy of the electron is significant in this case??
  2. jcsd
  3. Jul 1, 2004 #2
    what do u mean excited. Do u mean like passing a current through them?? Cause if thats what u mean, there is no temp change, only photon emmision.
  4. Jul 1, 2004 #3


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    I'm guessing that it does, but thermo is not my strong point. If the atoms are excited, then they are more likely to emit higher frequency radiation (when they spontaneously decay). I would expect this to have an overall shifting effect of the peak of the radiation to a higher frequency, which means a higher temperature, if I'm not mistaken.
  5. Aug 29, 2007 #4
    Anyone know what the typical temperature in the ion tail of a comet is as it nears the Sun? Thanks.
  6. Aug 29, 2007 #5

    Claude Bile

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    Undoubtedly, yes.
    I don't understand this part of the question. Could you elaborate further?

    Last edited: Aug 29, 2007
  7. Aug 29, 2007 #6


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    In a plasma, in which there are free electrons and ions/nuclei, one refers to ion and electron temperatures which are in equilibrium in the absence of external excitation. The temperature is related to the kinetic energy, and there is a distribution of temperature/kinetic energy. It doesn't make much sense to talk of a temperature of a bound electron, but rather temperature would be related to the kinetic energy of the atom.

    For atoms in solids and liquids, the temperature is related to atomic vibrations.
  8. Aug 30, 2007 #7
    When you calculate the phonon heat capacity of a solid you assume that the electron contribution is negligible. I believe that this assumption is only viable in some substances. I am not sure whether this means that a substance at a given temperature may have fewer phonon exitacions than one would expect from a pure phonon model.
  9. Sep 2, 2007 #8


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    "Temperature" as such is not really a well defined quantity in physics.One has be very specific about WHICH temperature one is refering to.
    If you e.g. do electrical transport experiments at low temperatures the "electronic" temperature (the temperature you measure in an electrical measurement) is usually higher than the phonon temperature; and the difference can be quite significant.
    The reason is simply that the electron-phonon interaction times become rather long at temperatures below about 100 mK. Hence, any "hot photons" that reach the device via the measurement leads will raise the temperatures of the electrons more than the temperature of the phonons.
    Temperatures of about 200 mK or so are frequently seen even when the phonon temperature of the chip the device is fabricated on is at around 20 mK.

    You can actually use the reversed effect as well. By using electronic cooling it is possible to lower the temperature of the electronos well below that of the phonons (the lattice)
  10. Sep 2, 2007 #9
    Atoms are excited and ionized all the time, even when everything is in thermal equilibrium. If they are, then the excitation and ionization obviously doesn't contribute to any change in temperature. The question actually isn't well posed.
  11. Sep 2, 2007 #10

    Claude Bile

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    Good point, I assumed the excitation was due to external pumping, like one might find in a laser.

  12. Sep 3, 2007 #11
    it should also be pointed out that at room temperature nearly everything will be in the ground state.
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