513.001 Molecular and Solid State Physics

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Ewald's sphere - 1

X-ray diffraction is performed on an orthorhomic crystal (a=2nm, b=3nm, c=1nm). The primary x-ray beam propagates within the (001) plane and also the detector scans the (001) plane. The problem is solvable in two dimensions, i.e., Ewald's sphere becomes a circle.

Which reflections are visible in the diffraction pattern when the primary x-ray beam propagates
        (a) in the [010] direction and has a wavelength of 2.08nm
        (b) in the [120] direction and has a wavelength of 2.28nm

Hint: Please solve the problem graphically. The first part of the problem can be solved by by drawing only the reciprocal lattice. For the second part of the problem the real lattice as well as the reciprocal lattices have to be drawn, for simplification use the same origin for both lattices