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X-ray diffraction or reflection?

  1. Dec 24, 2013 #1
    In x-ray diffraction , even though its reflection is happening , we call this as x ray diffraction. why is it so?? i don't know whether it has been discussed previously here.
     
  2. jcsd
  3. Dec 24, 2013 #2

    TumblingDice

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    Actually its diffraction that's happening. The terminology 'reflections' applies to the spots/patterns generated when x-rays diffract through a set of evenly spaced planes in a crystal. It's the mathematics of the monochromatic frequency of the x-rays and the angle of diffraction as the crystal is rotated. Diffraction patterns of spots/reflections are generated when the resulting wave patterns coincide and support each other.
     
  4. Dec 30, 2013 #3
    does anybody have any other answer????
     
  5. Dec 31, 2013 #4
    Reflection and diffraction are really two different aspects of the same thing. The term reflection is used mostly for what happens at the surface of a homogenous medium. This does occur for x-rays, but only at very small angles, because the index of refractions is very very close to 1. Nevertheless the effect is used for things like space-based x-ray telescopes, focusing and harmonic rejection of synchrotron radiation, etc.

    http://en.wikipedia.org/wiki/X-ray_optics#Reflection

    Diffraction relies on the (constructive) interference of wavelets scattered from a period arrangement of objects. For x-rays that can be a crystal lattice, an artificial multilayer, a Fresnel lens structure, etc. Diffraction does not necessarily happen at a surface. In fact, Max von Laue and coworkers first discovered x-ray diffraction in a transmission geometry.

    http://www.iucr.org/__data/assets/pdf_file/0010/721/chap4.pdf, near page 40.
     
  6. Jan 1, 2014 #5

    TumblingDice

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    M Quack added good info and links for reflection and diffraction.

    Here's another wiki link directly to X-ray Crystallography:
    http://en.wikipedia.org/wiki/X-ray_crystallography

    The link has some more good stuff that directly addresses your question regarding, "why":
     
  7. Jan 2, 2014 #6
    You (actually Wikipedia :wink:) are telling is that reflection ".... producing a diffraction pattern of regularly spaced spots known as reflections". But reflection is a physical phenomenon, so how cold you term spots as reflection??
     
  8. Jan 3, 2014 #7
    That is just nomenclature. At the Bragg condition the crystal "reflects" (should be diffracts!) x-rays, that's why it is known as Bragg reflection. This is the term that everybody uses, and I do not know of any better term. Get used to it.
     
  9. Jan 4, 2014 #8
    Okay.. Thank you.....
     
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