1. A.E. GunnæsMENA3100 V08 Electron Diffraction (ED) in the transmissions electron microscope

2. A.E. GunnæsMENA3100 V08 JEOL 2010F in the Research park

3. A.E. GunnæsMENA3100 V08 Basic TEM Electron source (HV= 200kV) Apertures Sample holder Fluorescence screen Film box Pedals for tilting the sample Magnetic lenses Vacuum in the column better than 10 -6 Pa

4. A.E. GunnæsMENA3100 V08 The lenses and apertures in a TEM Sample Filament Anode ΔU= ~100-1000 kV 1. and 2. condenser lenses Objective lens Intermediate lenses Projector lens Selected area aperture (diffraction aperture) Objective aperture Condenser aperture Electron source: ●Tungsten, W ● LaB 6 ● FEG Image Fluorescence Screen (ZnS or ZnS/CdS powder) Recording media: ●Film ● Imaging plates ● CCD camera ●TV camera λ= h/(2meV) 0.5 (NB non rel. Expr)

5. A.E. GunnæsMENA3100 V08 Simplified ray diagram Objective lense Diffraction plane (back focal plane) Image plane Sample Parallel incoming electron beam Si 1,1 nm 3,8 Å Convergent beam -Discs in diffraction -Micro diffraction -STEM mode -Chemical analysis

6. A.E. GunnæsMENA3100 V08 Electron diffraction Elastic scattered electrons Only the direction of v is changing. (Bragg scattering) Elastic scattering is due to Coulomb interaction between the incident electrons and the electric charge of the electron clouds and the nucleus. (Rutherford scattering). The elastic scattering is due to the average position of the atoms in the lattice. Reflections satisfying Braggs law: 2dsinθ=nλ Inelastic scattered electrons Direction and magnitude of v change. Energy is transferred to electrons and atoms in the sample. -It is due to the movements of the atoms around their average position in the lattice. - It give rise to a diffuse background in the diffraction patterns. Electrons interacts 100-1000 times stronger with matter than X-rays -more absorption (need thin samples) -can detect weak reflections not observed with x-rays

7. A.E. GunnæsMENA3100 V08 Sample preparation TEM grids 3 mm

8. A.E. GunnæsMENA3100 V08 Sample holders Sample positions Cooling Standard Heating