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IFFAT FATIMA

IFFAT FATIMA. UOG. ELECTRON MICROSCOPE. Contents. History LM Vs EM Electron microscope Principle Types of EM Application & importance. History of Microscope. 1590-tube microscope by dutch glass maker. 1665-Robert hooke’s microscope. Continued…………………………….

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IFFAT FATIMA

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  1. IFFAT FATIMA UOG

  2. ELECTRON MICROSCOPE

  3. Contents • History • LM Vs EM • Electron microscope • Principle • Types of EM • Application & importance

  4. History of Microscope 1590-tube microscope by dutch glass maker 1665-Robert hooke’s microscope

  5. Continued…………………………… 1674-Antonee van leeuwenhooke TEM co-invented by Ernst Ruska (1931)

  6. Main characteristics of microscope • Resolution

  7. Magnification

  8. Light Microscope Vs Electron microscope

  9. Comparison Light microscope Electron microscope Resolution: 0.2nm Magnification: 2‚000‚000x Illumination: Electron Electromagnetic lenses Objects seen: orgenelles‚ proteins‚ viruses‚ small molecules etc. Dead specimen Higher resolving power Focus: vaccum & magnetic lense Resolution: 0.2μm to 200nm Magnification: 2000x Illumination: Light Glass lenses Objects seen: frog's egg cells‚ cell wall‚ cilia‚ flagella‚ nucleus & other organelles etc. Living specimen Lower resolving power Focus: condenser lense

  10. Electron microscope • Electron microscope is a scientific instrument that uses a beam of energetic electrons to examine objects on a very fine scale. Why electron beam? • Wave nature of particles

  11. Types of Electron microscope

  12. Transmission electron microscope Instrumentation • Electron Source • Electromagnetic lense system • Sample holder • Imaging system

  13. Working • Emission of a high voltage beam of electrons. • Focusing of beam on specimen. • Transmission through the specimen. • Magnification of the image. • Recording of the image by fluorescent screen, light sensitive sensor (camera).

  14. TEM

  15. Sample preparation • Fixation • Rinsing • Post fixation • Dehydration • Infiltration • Polymerization • Sectioning

  16. Applications • Ultra-structure analysis • Crystal structure

  17. Scanning Electron microscope • Emission of a beam of by an electron gun. • Passage of electron beam through the vacuum. • Focusing of beam down toward the sample. • Ejection of X-rays & es. From sample after hitting. • Collection of by detectors & conversion to a signal. • Transmission of signal to a screen/ final image

  18. Scanning EM

  19. Sample preparation • Metals require no preparation • Non metals require coating of a thin layer of conductive material.

  20. Applications • Medical & physical science • Semiconductor industry • Examination of a large specimen range.

  21. Any Q?

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