1. X-Ray Experiment Presenter: Xu Luo Dec 16, 2009

2. Part 1. Introduction  Powder method A monochromatic X-ray beam scatters off the randomly oriented powder crystallites, giving rise to diffraction peaks at detector angle 2θ, that satisfy the Bragg’s Law:

3.  Laue Method(Back Reflection)  Reciprocal Lattice and Ewald Sphere Note: A given reflection will only diffract if its reciprocal lattice point intersects the Ewald sphere

4. 2. Two kinds of explanation of the Back reflection Laue Method A continuous band of X-rays is used to produce diffraction spots on a 2D film where the incident and scattered wave direction satisfy:

5. Part 2. Experiment Setup Planes of a zone produce loci of points on film that are either hyperbolae or straight lines.

6. Part 3. Analysis 1. The Greninger Chart

7. 2. Stereographic projection and Wulff net

8. 3. Determination of the zone axis for a Laue picture hyperbola

9. Part 4. Results 1. In our experiment, we found two zone axis poles on the Wulff net. The γ and δ value of them are given below: zone axis 1:, zone axis 2:,

10. 2. By comparing the zone axis points with several standard projections. We noticed that when rotating the Wulff net over the [110] standard projection, the zone axis points coincide with the points and. Conclusion : The A-B axis (the direction of the X-ray) is [110],and the two zone axis’s we found are : ( on Wulff net); ( on Wulff net)

11. Thanks!