Electron microscopy uses beams of electrons instead of light to magnify objects down to the nanometer scale. There are two main types: transmission electron microscopy (TEM), which uses electrons transmitted through thin samples to form images, and scanning electron microscopy (SEM), which scans surfaces with electrons. Electron microscopes were developed in the early 20th century to overcome the magnification and resolution limits of light microscopes. They have many applications in medicine, materials science, and biology due to their ability to reveal ultrastructures. However, they also have limitations such as high costs and complex sample preparation requirements.

1. Electron Microscopy
Presented to: Dr. Muhammad Waseem
Presented by: Rimsha Khan
2020-PHD-1187

2. Contents:
 What is Electron Microscope
 History of Electron Microscope
 Why do we need Electron Microscope?
 Types of Electron Microscope
 Scanning Electron Microscope
 Transmission Electron Microscope
 Advantages of Electron Microscopy
 Limitations of Electron Microscopy
 References

3. What is Electron Microscope?
A special type of Microscope having a high resolution of images, able to
magnify objects in nano meters, which are formed by controlled use of
electrons in vacuum captured on the screen.
Electron Microscopy:
Type of microscopy that uses beam of electrons to create an image of
sample, similar to optical microscopy except with electrons and photons.

4. Electron Microscope:

5. History of Electron Microscope
 In 1897 J.J Thomson discovered the electron.
 In 1924 Louis deBrorglie identified wavelength of electron.
 In 1929 E. Ruska had thesis on magnetic lenses.
 In 1931 Knoll and Ruska built first electron microscope.
 In 1938 Von Borries and Ruska built the first practical
electron microscope.

6. Why do we need Electron Microscope?
 Light microscope are limited by the physics of light to 500x or
1000x magnification and resolution of 0.2 micro meters.
 In 1930 It was an early scientific desire in biomedical research
to investigate the detailed structure of tissues, cells, organelles
and macromolecular complexes.
 This required 10,000x plus magnification which was not just
possible using electron microscope.

7. Light Microscope Comparison with Electron Microscope

8. Types of Electron Microscope
 Transmission Electron Microscopy (TEM)
(to study inner surfaces)
 Scanning Electron Microscopy (SEM)
(to study surface of objects)

9. Transmission Electron
Microscopy (TEM)
 Transmission electron
microscopy (TEM) is
a microscopy technique in which a beam
of electrons is transmitted through a
specimen to form an image.
 The specimen is most often an ultrathin
section less than 100 nm thick or a
suspension on a grid.

10. Scanning Electron Microscope
 A scanning electron microscope (SEM) is a
type of electron microscope that produces
images of a sample by scanning the surface
with a focused beam of electrons.
 The electrons interact with atoms in the
sample.
 It produce various signals that contain
information about the surface topography
and composition of the sample.

11. The Electron Beams in SEM:
These types of electron beams produce in SEM
 Secondary electrons (SE)
 Back Scattered electrons (BSE)
 X-Rays
 Light Rays (cathodoluminescence)

13. Advantages of Electron Microscopy
 As diagnostic tool in medicine : e.g. renal biopsy
 Cellular tomography: 3D images of sub cellular macromolecular
objects.
 Cancer research: to study tumor cells ultra structures
 Toxicology : scientific study of adverse effects that occur in living
organisms due to chemicals
 Virology: viral structures investigation.
 Cryo electron microscopy: Cryogenic electron microscopy is an
electron microscopy technique applied on samples cooled to cryogenic
temperatures. Surfaces images of frozen materials.
 Forensics: it detects undetectable presence of materials on evidences
 3D images of microorganisums

14. Limitations of Electron Microscopy
 The main disadvantages are cost, size, maintenance, researcher training and
image artifacts resulting from specimen preparation.
 This type of microscope is a large, cumbersome, expensive piece of equipment.
 Extremely sensitive to vibration and external magnetic fields.
 Extensive sample preparation.
 Time consuming process.
 Structure of sample may change during thin film of sample preparation .

15. References:
 https://www.slideshare.net/ISHRAKMAHADI/electron-microscope-
67879230
 https://www.google.com/search?bih=646&biw=1366&hl=en&sxsrf=A
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 https://www.slideshare.net/search/slideshow?searchfrom=header&q=ele
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