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Homework Help: What is the atomic spacing D of this crystal?

  1. Nov 29, 2008 #1
    1. The problem statement, all variables and given/known data
    X rays with wavelength 0.10 nm are incident on a crystal with a hexagonal crystal structure. The x-ray diffraction spectrum is shown in the figure.

    Figure: knight_Figure_24_40.jpg

    What is the atomic spacing D of this crystal? (in nanometers)

    2. Relevant equations

    The Bragg condition:
    2*D*cos(theta)=m*lamda where, m=1,2,3...

    3. The attempt at a solution

    (m+1)/(m) ==> cos(50.1)/cos(71.3) = (2/1)

    (m+1)/(m)==> cos(15.8)/cos(71.3) = (3/1)

    D=(2*lamda)/(2*cos(theta_2)==> (lamda)/cos(theta_2)==> (0.10nm)/cos(50.1)=0.16nm

    I just followed a similair example in the book. Maybe I'm getting it wrong because I'm not factoring anything in about the hexagonal shape in my math? *Note: this is a challange problem.
  2. jcsd
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