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Gamma radiation photoelectric effect

  1. Jan 6, 2012 #1
    I read earlier that the photoelectric effect is when electromagnetic radiation essentially overcomes an electrons binding energy and converts it to electricity, which is how solar panels function.
    But why is it that gamma radiation isn't being used to capture energy? If gamma radiation has a higher frequency, then it should have more energy, and thus the KE of the released electrons should be more. So why is this not currently being done? Am I missing something?
     
  2. jcsd
  3. Jan 6, 2012 #2
    What you are missing is that Gamma rays are both deadly and rare. Sunlight is much safer and available almost everywhere.
     
  4. Jan 6, 2012 #3
    To add to what Antiphon said, try doing a calculation where the output of 1 Curie of Cobalt-60 is completely converted to electricity using a solar panel, and you'll see just how little wattage this produces from a dangerously high 1 Curie source.
     
  5. Jan 6, 2012 #4

    ZapperZ

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    There's a little bit of misunderstanding here.

    The "photoelectric effect" that we normally deal with is the phenomenon of light impinging on a surface, and then the liberation of electrons from that surface. In fact, if we want to be even more precise, the phenomenon that is described via the Einstein photoelectric effect is the impinging of light of a certain frequency range on a metallic surface.

    What this means is that it is the liberation of the conduction electrons that has overcome the work function of the metal. This is important to note because it is no longer a scenario that involves isolated atoms for one very obvious reason - isolated atoms do not have conduction/valence bands.

    Now, the problem with gamma rays is that the interaction can be very different. Where there is a certain small probability of a "photoelectric effect" type phenomenon, gamma rays tend to interact more with not only a deeper, core-level energy states, but also with the nucleus of the material. When that occurs, you are no longer in the "photoelectric effect" regime (Einstein's equation no longer works). You can have a number of different phenomena going on - nuclear excitation, different types of scattering, etc.. etc. You just don't get a simple "electrons emitted at higher energy" phenomenon. Even x-rays can induce more complicated processes (that's why x-ray detectors are not some simple photodetectors that we use for UV/visible/IR range).

    The higher the energy of the photon, the more exotic/complex processes that can occur when it interacts with matter.

    Zz.
     
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