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Exploring Electron Microscopy: The Science Behind Magnification

Delve into the fascinating world of electron microscopy with Timothy G. Standish, Ph.D. Learn how these instruments provide high-resolution images by utilizing electron beams instead of light. Discover the differences between Scanning Electron Microscopes (SEM) and Transmission Electron Microscopes (TEM) and their applications in scientific research.

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Exploring Electron Microscopy: The Science Behind Magnification

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  1. Psalm 119:99,100 99 I have more understanding than all my teachers: for thy testimonies are my meditation. 100 I understand more than the ancients, because I keep thy precepts.

  2. Electron Microscopy Timothy G. Standish, Ph. D.

  3. History and Applications • Electron microscopes were developed around the same time as the development of television sets and utilize much of the same technology • They take advantage of the short wavelength of electrons. As the wavelength is shorter, higher resolution is possible than with regular light microscopes • Scanning Electron Microscopes (SEM) are analogous to dissecting microscopes • Transmission Electron Microscopes (TEM) are similar in principle to compound microscopes

  4. A Television Monitor Electron beam Magnets - Electron Gun Phosphore coated screen Vacuum +

  5. Scanning Electron Microscopy • SEM is very good for looking at surfaces • SEM gives almost infinite depth of field • SEM cannot show color • With the right detectors SEM can be used to determine the elements in a sample • SEM can go to high magnifications, but cannot achieve magnifications as high as those achieved with Transmission Electron Microscopy

  6. Scanning Electron Microscope Big Hairy Computer ….. - +

  7. Scanning Electron Microscope Filament Electrons - Focused Electron beam Sample + Stub Magnet “lenses” Beam deflector

  8. Scanning Electron Microscope Filament Electrons Magnet “lenses” - Focused Electron beam Beam deflector Electron detector Big Hairy Sample Computer + ….. Stub Reflected electrons

  9. Scanning Electron Micrographs May Fly Head Bee Eye

  10. More S. E. Micrographs Burr Leaf With Bacteria Anther

  11. Transmission Electron Microscopy • TEM allows for very high magnification due to the short wavelength of electrons • TEM is very good for looking inside cells, but is not very good for studying surfaces • Preparation of samples for TEM is time consuming and difficult • No natural color is possible with transmission electron micrographs

  12. Transmission Electron Microscope Filament Electrons Magnet “lenses” - Focused Electron beam Beam spreader Sample Ultra vacuum To a very efficient pump + Phosphore coated target Window

  13. Transmission Electron MicrographDiaphragm 24,000 X

  14. Transmission Electron MicrographSperm Tail XS, 28,000 X

  15. The End

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