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Absorption Lines from discrete energy

  1. Nov 5, 2011 #1
    I know that an atom "absorbs" a particular frequency of energy depending on which element and which electron in this element.
    The question is (for example) if we take one known emission frequency from a particular element, and use that exclusively to bombard another element for a lower absorption line, would this particular emission frequency be broken down into two or more events. The target absorbing a piece of the source energy and the remainder being kicked away.

    Or must the electrons always be hit with the perfect frequencies to make their state changes?

    If there is a web site that gives numeric data could someone post it for me please. I searched and found oddles of pages explaining the basics but haven't found any that answer this clearly.

  2. jcsd
  3. Nov 7, 2011 #2
    Yes, but it's complicated. If the electron stays bound and simply changes levels in the same atom, it must absorb light of the right frequency. It can't absorb higher energy light than it needs and then throw away the extra (how would it do that?). Photon absorption is a resonance phenomenon. If they are not in resonance, than the absorption is much less likely. Note that the electron does not have to be hit with the "perfect" frequency, because of Heisenberg uncertainties, natural linewidth broadeding mechanisms (such as thermal agitation), and the nature of resonance itself, but it has to be hit with close to the perfect frequency to have a significant chance of transitioning.

    If the electron absorbs enough energy to be freed, than it is a different story. It can carry away the excess energy as kinetic energy. In such a case, any frequency above some critical frequency would be absorbed by the electron. This is the photoelectric effect. Frequencies are typically in the ultraviolet to x-ray region to have enough energy to knock free electrons.
  4. Nov 7, 2011 #3
    What kind of numeric data do you want? The frequencies at which a material's electrons can transition is called its absorption spectrum. If you want numeric data for the absorption spectrum of a specific material, you should google for instance "absorption spectrum gold", or search scholarly journals with similar keywords. I see articles all the time publishing new and improved spectroscopy results for certain materials.

    Try http://www.spectralcalc.com/spectral_browser/db_intensity.php" [Broken]

    The government also archives and provides freely a lot of spectroscopy information:
    http://www.nist.gov/pml/data/asd.cfm" [Broken]
    Last edited by a moderator: May 5, 2017
  5. Nov 7, 2011 #4
    I was talking about bound energy transfers.
    Thanks for the clear answer within quantum probabilities ;)
    The width of the spectral frequencies is basically the doppler effect from the kinetic energy of an individual atoms.

    In a molecule, there is a known electron configuration for each bound member atom.

    Is there studies where the spectra of one atom (in a particular molecule) matches the frequency of another atom (in the same molecule) which it is bound, within say some range that is of the magnitude of typical atomic kinetic energy?

    Where I am going is the question, Can all molecular combinations theoretically be calculated based on possible spectra of the member elements?

    Thanks for the direction to find the spectroscopy information...
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