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Homework Help: Need help using the atomic form factor

  1. Nov 3, 2014 #1
    1. The problem statement, all variables and given/known data

    I need to calculate interference peaks using the atomic form factor for several lattice types for a lab report. I was given the expected answers but told I should also be able to calculate them.

    Expected results for rocksalt (eg NaCl):

    h+k+l = 2n
    fh+k+l = 4(fa+fb)

    h+k+l = 2n+1
    fh+k+l = 4(fa-fb)

    2. Relevant equations

    Sk = ∑ fj(K)*e(iK.dj )

    where fj(K) = atomic form factor = ∑p e(iK.rp )

    dj = distance between to lattice points

    rp = distance between to basis points

    K = wavenumber

    3. The attempt at a solution

    For the geometrical form factor:

    Sk= ∑e(iK.dh+k+l )

    D(k-k`)=2πm or ei(k-k`)D=1

    Sk= 1+ (-1)((n1+n2+n3))

    This is the answer for a mono-atomic BCC lattice.

    NaCl has atoms at basis points Na(0,0,0) and Cl 1/2(1,1,1).

    Sk = ∑ ∑ e(iK.rp )*e(iK.dj )
  2. jcsd
  3. Nov 8, 2014 #2
    Thanks for the post! Sorry you aren't generating responses at the moment. Do you have any further information, come to any new conclusions or is it possible to reword the post?
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