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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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Presentation Transcript
contents
Contents
  • History
  • LM Vs EM
  • Electron microscope
  • Principle
  • Types of EM
  • Application & importance
history of microscope
History of Microscope

1590-tube microscope by dutch glass maker

1665-Robert hooke’s microscope

continued
Continued……………………………

1674-Antonee van leeuwenhooke

TEM co-invented by Ernst Ruska (1931)

comparison
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

electron microscope1
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
transmission electron microscope
Transmission electron microscope

Instrumentation

  • Electron Source
  • Electromagnetic lense system
  • Sample holder
  • Imaging system
working
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).
sample preparation
Sample preparation
  • Fixation
  • Rinsing
  • Post fixation
  • Dehydration
  • Infiltration
  • Polymerization
  • Sectioning
applications
Applications
  • Ultra-structure analysis
  • Crystal structure
scanning electron microscope
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
sample preparation1
Sample preparation
  • Metals require no preparation
  • Non metals require coating of a thin layer of conductive material.
applications1
Applications
  • Medical & physical science
  • Semiconductor industry
  • Examination of a large specimen range.
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