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A To capture the infrared light

  1. Jan 21, 2019 #1
    hello :

    i have a small question , can we use multi layer thin films to increase absorption of infrared spectrum , on certain surface , ?

    taking in mind that we use the same kind of thin film for each layer .
    is that possible ?

    best
    hagop
     
  2. jcsd
  3. Jan 22, 2019 #2
    You can certainly increase absorption by using thin layers of different materials. What matters is change in refractive index. This is quite similar to anti-reflection coating, however you would have to use lossy optical materials for your anti-reflection coating to get absorption (as opposed to transmission)
     
  4. Jan 28, 2019 #3
    What about x-rays
     
  5. Jan 29, 2019 #4
    In x-rays materials do not respond as effective media anymore, so the above approach will probably fail. Materials still scatter x-rays, so maybe one can try Anderson localization tricks, i.e. send x-rays at disordered media such as glass. Or simply use thicker layers. This is all on the level of a hypothesis, I do not work with x-rays.
     
  6. Jan 29, 2019 #5
    But if the thickness of the thin-film is near the wave length of the x-ray incoming wave ?
     
  7. Jan 29, 2019 #6
    x-ray wavelength is on the scale of few Angstrom. Does it make sence to talk about electromagnetic media of such thickness? There is graphene and other 2d materials, but I would not call them electromagnetic media.
     
  8. Jan 29, 2019 #7
    Multiple stack of thin films of that thickness
     
  9. Jan 29, 2019 #8
    Initially it was infrared, then x-ray, then single-wavelength thick layer, now many layers ... Is there anything specific you are after?
     
  10. Jan 30, 2019 #9
    You answered the infra red question,then you indicated that single layer is not going to effect (the question of single layer was not clear my mistake) ,
    But in case of multiple layers if they are thin enough that what I was wondering about or asking about
     
  11. Feb 7, 2019 #10
    Not particularly. Typically, for x-ray shielding bulk amounts of lead or other high atomic number materials, such as tungsten-filled polymers are used.
    For infrared absorption the absorption process would typically be a band-to-band transition or the excitation of a vibrational/rotational mode.
    As x-rays are much higher energy, different processes dominate (for instance the generation of secondary electrons and the subsequent bremsstrahlung). In principle, you can have high-absorption if the x-ray energy is at an absorption edge of the material in question, however you would still generate ionising radiation via Auger processes and bremsstrahlung.
     
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