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Historical question concerning Moseley's experiment

  1. Jul 11, 2006 #1
    This question may be beyond the scope of this forum, but I'll give it a go anyway. Moseley's landmark experiments in 1913 related the square root of the frequency of characteristic X-rays of an element to integer values, which he equated to the element's atomic number. He measured the wavelength of this X-ray radiation using a Bragg diffractometer equipped with a potassium ferrocyanide crystal. My question is why he would choose a complicated crystal structure like potassium ferrocyanide instead of something simpler such as NaCl? I highly recommend the following website, which has an online version of Moseley's original paper:

  2. jcsd
  3. Jul 11, 2006 #2


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    Mostly, I imagine, the reason would have been to maximize signal to noise ratio. So, you want a highly planar single-crystal surface and you want reasonably strong reflections of characteristic lines at angles where reflection of Bremsstrahlung is small. ie: You want a high structure factor for the right plane spacing (to ensure the latter) and you want the planes with these spacings to be cleavage planes of the crystal (for the former requirement).
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