1. Probing Lattice Dynamics Pampa Devi April 29,2009

2. Bragg Law Pump Probe Set Up Velocity Mismatch Problem Way to overcome it Go Through….

3. Bragg Law W. L. Bragg presented a simple explanation of the diffracted beams from a crystal based on a reflection from planes of atoms. d { dsin    The difference in the paths traversed by the two beams shown in the figure is: 2dsin  = n

4. X-Ray diffraction Electron Diffraction

6. Pump Probe Photography

7. Au Powder Diffraction

8. 8 Committee Meeting # 2 Seeing is believing.. Hard to see …  Ruan et al.

9. Ultrafast Electron Diffraction Groups Around the World

10. Velocity Mismatch Picture Pump (Laser): c Probe (Electron Beam): 0.34 c Why not use laser as probe ???

11. Accessories : Peter Baum and Ahmed H. Zewail No excitation Excitation After Excitation

13. Passing through a grating does the job…

14. Implementation