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B Photoelectric effect and metal's delocalised electrons

  1. Dec 10, 2016 #1
    Hi all,
    With the photoelectric effect is it the 'sea' of free electrons that are ejected if the photons are above threshold frequency (i.e. Conduction band electrons ) rather than valence electrons ? If say very energetic gammas are used then suppose this could knock out valence electrons but guess that is then just normal ionisation events ?
    Is this thinking correct?
    Would really appreciate any thoughts.
  2. jcsd
  3. Dec 10, 2016 #2
    If you are going to start exposing metals to say x-ray photons I think you have stepped outside the scope of the PE effect experiment.
  4. Dec 10, 2016 #3
    It seems to only talk about photoelectric effect in connection with metals and not non-metals so that made me think it might be delocalised electrons that are released.
  5. Dec 10, 2016 #4
  6. Dec 10, 2016 #5
    Interesting thought thanks for that
  7. Dec 10, 2016 #6


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    The "standard" photoelectric effect is (i) done on metals and (ii) uses, at most, UV sources. So the photoelectrons emitted are from the conduction band.

    Now it doesn't mean that this phenomenon hasn't changed from that. The overall area is now generally known as photoemission spectroscopy, and it encompasses a huge field. This includes x-ray photoemission spectroscopy (XPS). This technique does probe deeper levels of the material which are usually known as core-levels. Here, it no longer just probe the conduction band, but also electrons that still localized to the atoms making up the material.

    Photoemission techniques have also been done on semiconductors and insulators to a certain degree. In fact, most high quantum efficiency photocathodes are made of semiconductors.

  8. Dec 10, 2016 #7
    That great Zz, I didn't know the link with photoemission. Very interesting. G
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