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Objects melt and burned if a high energy ray is shined unto it?

  1. Mar 22, 2007 #1
    Will all objects melt and burned if a high energy ray like gamma ray is shined unto it? My guess is no, since gamma photons will be absorbed by the objects if the photon energy is the same as the transition levels in the object. If it doesn't, then the photons will not be absorbed, and just bounced off.
    Is my understanding right?
  2. jcsd
  3. Mar 22, 2007 #2
    You can also get energy transfer into matter via Raman scattering. So if the light intensity is high enough and long enough you will get energy into the object. But, it may not be particularly efficient. In x-ray crystallography, for example, x-ray damage to the crystal is well known.
  4. Mar 22, 2007 #3
    I searched on Raman scattering, and it explains that in quantum mechanics the scattering is described as an excitation to a virtual state lower in energy than a real electronic transition with nearly coincident de-excitation and a change in vibrational energy.

    If the atoms are capable of going to these virtual states, why should we distinguish them as virtual? Why not just a real transition?

    Further, all the while I was talking that if atoms are bounded within a certain potential, say a finite well, it has quantized energies. Hence, only photons of specific energy can excite it to other levels. The only situation where an atom will absorb and have inelastic scattering is when it is a free particle, like in a Compton scattering.
  5. Mar 22, 2007 #4
    Yes, the Compton effect is a good example of another kind of inelastic scattering. It may result in some of the crystal damage I mentioned in x-ray experiements. The virtual state mentioned in connection with the Raman effect hasn't been observed AFIK. Whatever the case, the Raman effect is very real, resulting in the excitation of molecular rotational and vibrational states and can be used in condensed phases. Chemists have used Raman spectroscopy quite a lot - a search on "Raman spectrscopy" at amazon.com turned up over twenty books on the subject. The intensities of Raman absorptions can be computed; they are related to polarization.

    That's two examples of matter absorbing energy from photons larger than quantum state separations, both witnessed in decades of experiment.

    The quantum efficiency of these processes is usually quite small compared to hitting an allowed pure quantum transition with the right-sized photon. In the case of Compton scattering, it complicates the analysis of the x-ray experiment for crystal structure determination.
  6. Mar 22, 2007 #5


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    It is the excitation of some of these modes that actually results in melting. So your reasoning is incorrect.

    Not likely. In most materials, gamma ray photons will be transmitted through it.
  7. Mar 22, 2007 #6
    You ignore the scattering processes above. A correct statement would be: "In materials, most gamma ray photons will be transmitted through."
    Most, maybe, but not all, for sure.
  8. Mar 22, 2007 #7


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    Of course, there's some tiny cross section for various scattering events - I was only pointing out that reflection was not typically the most likely outcome (compared to transmission).
    Last edited: Mar 22, 2007
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