The electron microscope. Features of the electron microscope Electron beam has short wavelength so...
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Transcript of The electron microscope. Features of the electron microscope Electron beam has short wavelength so...
![Page 1: The electron microscope. Features of the electron microscope Electron beam has short wavelength so it can resolve objects well Electrons are negatively.](https://reader036.fdocuments.in/reader036/viewer/2022062407/56649d925503460f94a793d7/html5/thumbnails/1.jpg)
The electron microscope
![Page 2: The electron microscope. Features of the electron microscope Electron beam has short wavelength so it can resolve objects well Electrons are negatively.](https://reader036.fdocuments.in/reader036/viewer/2022062407/56649d925503460f94a793d7/html5/thumbnails/2.jpg)
Features of the electron microscope
• Electron beam has short wavelength so it can resolve objects well
• Electrons are negatively charged so the beam is focused using electro magnets
• Modern electron microscopes can resolve objects 0.1 nm apart and magnify up to 500 000 times
![Page 3: The electron microscope. Features of the electron microscope Electron beam has short wavelength so it can resolve objects well Electrons are negatively.](https://reader036.fdocuments.in/reader036/viewer/2022062407/56649d925503460f94a793d7/html5/thumbnails/3.jpg)
Transmission electron microscope (TEM)
• Specimen is specially prepared
• Thin slices of specimen are cut, preserved and stained
• Specimen is placed in chamber of the electron microscope. It is sealed and air is sucked out to create a vacuum
![Page 4: The electron microscope. Features of the electron microscope Electron beam has short wavelength so it can resolve objects well Electrons are negatively.](https://reader036.fdocuments.in/reader036/viewer/2022062407/56649d925503460f94a793d7/html5/thumbnails/4.jpg)
Transmission electron microscope (TEM)
• Electromagnets focus a beam of electrons that passes through the specimen onto a viewing screen
• Parts of the specimen absorb electrons so appear dark, other parts allow electrons to pass through so appear light
• An image is produced on a screen, this can be photographed to produce a photomicrograph
![Page 5: The electron microscope. Features of the electron microscope Electron beam has short wavelength so it can resolve objects well Electrons are negatively.](https://reader036.fdocuments.in/reader036/viewer/2022062407/56649d925503460f94a793d7/html5/thumbnails/5.jpg)
![Page 6: The electron microscope. Features of the electron microscope Electron beam has short wavelength so it can resolve objects well Electrons are negatively.](https://reader036.fdocuments.in/reader036/viewer/2022062407/56649d925503460f94a793d7/html5/thumbnails/6.jpg)
Scanning electron microscope (SEM)
• Specimen doesn’t need to be as thin
• Beam of electrons scans over rectangular area of sample surface
• Resolution from 1 – 20 nm
![Page 7: The electron microscope. Features of the electron microscope Electron beam has short wavelength so it can resolve objects well Electrons are negatively.](https://reader036.fdocuments.in/reader036/viewer/2022062407/56649d925503460f94a793d7/html5/thumbnails/7.jpg)
SEM - ant
![Page 8: The electron microscope. Features of the electron microscope Electron beam has short wavelength so it can resolve objects well Electrons are negatively.](https://reader036.fdocuments.in/reader036/viewer/2022062407/56649d925503460f94a793d7/html5/thumbnails/8.jpg)
SEM – blood cells
![Page 9: The electron microscope. Features of the electron microscope Electron beam has short wavelength so it can resolve objects well Electrons are negatively.](https://reader036.fdocuments.in/reader036/viewer/2022062407/56649d925503460f94a793d7/html5/thumbnails/9.jpg)
TEM - chloroplast
![Page 10: The electron microscope. Features of the electron microscope Electron beam has short wavelength so it can resolve objects well Electrons are negatively.](https://reader036.fdocuments.in/reader036/viewer/2022062407/56649d925503460f94a793d7/html5/thumbnails/10.jpg)
TEM - mitochondria
![Page 11: The electron microscope. Features of the electron microscope Electron beam has short wavelength so it can resolve objects well Electrons are negatively.](https://reader036.fdocuments.in/reader036/viewer/2022062407/56649d925503460f94a793d7/html5/thumbnails/11.jpg)
SEM – fish gills
![Page 12: The electron microscope. Features of the electron microscope Electron beam has short wavelength so it can resolve objects well Electrons are negatively.](https://reader036.fdocuments.in/reader036/viewer/2022062407/56649d925503460f94a793d7/html5/thumbnails/12.jpg)
SEM – fungal spore stalk emerging from stomata
![Page 13: The electron microscope. Features of the electron microscope Electron beam has short wavelength so it can resolve objects well Electrons are negatively.](https://reader036.fdocuments.in/reader036/viewer/2022062407/56649d925503460f94a793d7/html5/thumbnails/13.jpg)
TEM – endoplasmic reticulum
![Page 14: The electron microscope. Features of the electron microscope Electron beam has short wavelength so it can resolve objects well Electrons are negatively.](https://reader036.fdocuments.in/reader036/viewer/2022062407/56649d925503460f94a793d7/html5/thumbnails/14.jpg)
SEM – spider’s silk spigots