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Electron microscopy

Electron microscopy. 200801195 박송순. Electron microscopy. INDEX 1. Fundamentals 2. Scanning electron microscopy 3. Transmission Electron microscopy 4. Comparison. 1. Fundamentals. *Wave-Particle Duality (the matter wave) KE= =qV = (de Broglie relation) λ = (h=6.626 ).

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Electron microscopy

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  1. Electron microscopy 200801195 박송순

  2. Electron microscopy INDEX 1. Fundamentals 2. Scanning electron microscopy 3. Transmission Electron microscopy 4. Comparison

  3. 1. Fundamentals *Wave-Particle Duality (the matter wave) KE==qV = (de Broglie relation) λ=(h=6.626)

  4. 1. Fundamentals Coherent Offset *Bragg’s condition

  5. 1. Fundamentals

  6. 1. Fundamentals *Electron beam A tungsten filament A lanthanum hexa boride crystal(LaB6) CRT(Cathode Ray Tube) *Detector CCD(Charge Coupled Device) Film

  7. 2.Scanning Electron Microscope

  8. 2.Scanning Electron Microscope

  9. 2.Scanning Electron Microscopy

  10. 2.Scanning Electron Microscopy

  11. 2.Scanning Electron Microscopy *Interaction Volume The volume inside the specimen in which interactions occur while being struck with an electron beam. (higher atomic number materials absorb or stop more electrons :smaller interaction volume)

  12. 2.Scanning Electron Microscopy 1. Back-scattered electrons (elastic scattering) High energy produing characteristic X-ray 2. Secondary electron (inelastic scattering) Image(Brightness) the surface topography 3. Characteristic X-ray Identifying elements of the surface

  13. 2.Scanning Electron Microscopy *Sample preparation 1.Water-less samples 2.Electrical coating on nonconducting samples (Goldor Graphite)

  14. 2.Scanning Electron Microscopy *The Limitation of Resolution Size of beams & Focussing system

  15. 3.Transmission Electron Microscopy specimen CCD or Film

  16. 3.Transmission Electron Microscopy

  17. 3.Transmission Electron Microscopy *Back and Secondary scattered electrons Finding the positions & types of lattice defects using Bragg’s condition (Surface structure & Identifying elements) *Transmitted electrons Total e-=Absorbed e- + Transmitted e- (Dark) (Bright)

  18. 3.Transmission Electron Microscopy *Bright-field mode The image is seen as a dark feature on a bright background.(Sample absorbs e-) *Dark-field mode A detector placed in front of the sample collects the coherent back-diffracted e-, Bragg’s reflections.(Finding lattice defects)

  19. 3.Transmission Electron Microscopy *The Resolution Limits ①Astigmatism : Elliptical cross section ②Chromatic aberration : Polychromatic wave ③Spherical aberration : Inhomogenius magnetic focusing

  20. 3.Transmission Electron Microscopy

  21. 4. Comparison

  22. 4. Comparison 250nm 0.5~20nm 0.05nm

  23. 4. Comparison

  24. Thank you! QUESTIONS?

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