Electron Microscopy

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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ope&oq=limitations+of+&gs_lcp=CgZwc3ktYWIQARgAMgcIABDJ
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DEJECOgcILhCxAxBDUI3HI1jR6yNg0PsjaAFwAXgAgAGaBIgB8i
CSAQoyLTEzLjAuMS4xmAEAoAEBqgEHZ3dzLXdperABCsABAQ
&sclient=psy-ab
 https://www.slideshare.net/search/slideshow?searchfrom=header&q=ele
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