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Homework Help: Solid State electron diffraction

  1. Apr 19, 2007 #1
    1. The problem statement, all variables and given/known data
    A crystal with unknown lattice spacing is studied using electron diffraction.
    The electron wavelength is 3.7pm.

    a) assuming a simple cubic lattice, what is its size if the smallest diffraction peak is at 0.5 degrees?

    b) At what angle is the nxt peak?

    c) At what angle is the [122] peak?

    d) The [122] and [310] planes will be situated close to each other. Without calculating the angle at which the [310] peak scatters electrons, can the two peaks be resolved if the accuracy to which the angle can be determined is 0.03 degrees?

    e) Comment on the locations of the [220] peak and the second order peak of [110].

    2. Relevant equations
    [tex]n\lambda = 2dsin\theta[/tex]

    3. The attempt at a solution
    a) Rearranged the above equation to give d=2.12*10^-10 m=a

    b) said that the next peak will be at [110] and so d=[tex]\sqrt{2}[/tex]a, put that into the equation above to give theta = 0.71 deg.

    c) said that d=3a and put this into the above equation to give theta = 0.83 deg.

    d) I don't really understand how to go about this question. Any hints would be appreciated.

    e) I haven't fully looked at this part yet (stuck on the previous bit), but first off I would say that the locations of the peaks are in the same place. I think anything else would be a bonus!!

    Any help/comments would be appreciated.


  2. jcsd
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