Electron microscope
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The presentation discusses electron microscopes, highlighting their superiority in resolving power compared to light microscopes, due to the use of electron beams instead of light waves. It covers two types: Transmission Electron Microscope (TEM), which offers high magnification and resolution for detailed cellular structures, and Scanning Electron Microscope (SEM), which provides 3D images of surfaces but with lower resolution. Limitations include the inability to examine living cells and potential changes in specimen morphology during preparation.
![SOUTHEAST UNIVERSITY
Presentation of
Pharmaceutical Microbiology
[BPH-2013]
Presentation Topic: Electron Microscope
Date: 31.05.2016
Submitted to-
MOSHIQUR RAHMAN
Lecturer, Dpt. of Pharmacy, SEU
Submitted by
SYEDA SALIMA RIZAN ID 2015000300006
MAHMUDA SIDDIKA SHEFA ID 2015000300007
ALI ASRAF SOHEL ID 2015000300008
SOURAV SARKAR ID 2015000300009
NAYLA SHARMIN ID 2015000300011
Batch & section. 25th A](https://image.slidesharecdn.com/electronmicroscope-161006180230/85/Electron-microscope-1-320.jpg)
Electron microscope
- 1. SOUTHEAST UNIVERSITY Presentation of Pharmaceutical Microbiology [BPH-2013] Presentation Topic: Electron Microscope Date: 31.05.2016 Submitted to- MOSHIQUR RAHMAN Lecturer, Dpt. of Pharmacy, SEU Submitted by SYEDA SALIMA RIZAN ID 2015000300006 MAHMUDA SIDDIKA SHEFA ID 2015000300007 ALI ASRAF SOHEL ID 2015000300008 SOURAV SARKAR ID 2015000300009 NAYLA SHARMIN ID 2015000300011 Batch & section. 25th A
- 3. Electron Microscope The electron microscopes use electron beams and magnetic fields to produce the image instead of light waves and glass lenses used in the light microscopes. Resolving power of EM is far greater than that of any other compound microscope. This is due to shorter wavelengths of electrons. The wavelength of electrons are about 100,000 times smaller than the wavelength of visible light.
- 4. Type OF Electron Microscope
- 7. Transmission Electron Microscope (TEM) • First invented in 1931 (in Germany) • Can magnify up to 200,000 x (and beyond) • Similar to a light microscope except that a beam of electrons is used instead of light. The electrons that penetrate through the object and create an image which is then enlarged and then viewed on a computer monitor. • Samples of the object must be sliced very thin before using the TEM. (No living specimens.) • Very expensive and time consuming to prepare slides.
- 8. Transmission electron microscopes are the method of choice for viewing the detailed structure of cells and viruses. This microscope produces its image by transmitting electrons through a specially prepared, ultrathin section of a specimen. The specimen must be sectioned into extremely thin slices (20–100 nm thick) and stained or coated with metals that will increase image contrast. Salts of various heavy metals, such as lead. Osmium, tungsten and uranium are commonly used as stain. The TEM can also be used to produce negative images and shadow casts of whole microbes Transmission Electron Microscope
- 9. Because of extremely short wavelength of the electron beam used for magnification (only 0.05Å for 60-to-80-kV electrons), the transmission electron microscope has a very high resolution (practical resolution for biological applications is approximately 0.5 nm) and it produces useful magnification of up to X400,000. Transmission Electron Microscope
- 10. Uses of the TEM • Used in biological/medical research to investigate parts of cells and molecules. • Used in material science to study the structure and the weaknesses of crystals. • Used in nanotechnology.
- 11. Example images using TEMs
- 12. Example images using TEMs Marburg virus
- 14. Scanning Electron Microscope (SEM) • First invented in 1942 • Can magnify typically up to 10,000 x • Gives a 3D image of the surface of the object • Again, a beam of electrons is used instead of light. The electrons that bounce off the object create the image. The microscope scans a certain region of the object multiple times and then combines multiple images to create what we then see on a computer monitor as one 3D image. • No slicing needed so easier to prepare samples. Larger objects can be viewed. • Very expensive.
- 15. The scanning electron microscope provides some of the most dramatic and realistic images in existence. SEM create an extremely detailed three- dimensional view of anything from a fly’s eye to AIDS viruses escaping their host cells. To produce this image, it bombards the surface of a whole, metal-coated specimen with electrons while scanning back and forth over it. A shower of electrons deflected from the surface is picked up with great fidelity by a sophisticated detector, and the electron pattern is displayed as an image on a television screen. Its resolving power is not as high as transmission electron microscopy (20 nm). Scanning Electron Microscope
- 16. Uses of the SEM • Multiple uses - for viewing the surface of any microscopic object. • Insect parts • Bacteria • Food industry • Material science • Education • Art
- 17. Example images using SEMs •Mascara brush
- 18. Example images using SEMs • Moth antennae
- 19. Limitations of Electron Microscopy The cells cannot be examined in a living state (because the examination is carried out under high vacuum. ) Some morphological properties of the specimen may also be changed during the drying step involved in preparing the specimen. Low penetration power of the electron beam necessitates the use of very thin sections of the specimen to reveal the internal structures of the cell.