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Electron microscope question

  1. Sep 10, 2006 #1
    Is transmission electron microscope the original EM, and Scanning the better resolution one. What is the main difference between the two
  2. jcsd
  3. Sep 10, 2006 #2


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    They both use electrons.
    Other than that, I can't think of anything that's the same.
    I suppose you could say Scanning uses quantum tunneling electrons while the TM uses clasical electrons.
  4. Sep 10, 2006 #3


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    TEM was the first form of electron microscopy (the invention won Ruska his Nobel Prize). It also has a better resolution than SEM.

    The main difference between the two is what gets detected. In SEM, you detect backscattered and secondary electrons (these are electrons emitted due to collisions from the impinging beam and other secondary phenomena), while in TEM you directly detect the transmitted electrons. Consequently, it requires a very different sample preparation for the two techniques. Notably, TEM samples need to be extremely carefully thinned to ensure a reasonable signal to noise ratio. Sample preparation is relatively, a walk in the park for SEM samples. Also, with the SEM, you can raster the e-beam across the area of the sample and (reasonably quickly) collect surface information about a fairly large area. The inability to do this with the traditional TEM was overcome somewhat by incorporating a rastering capability into what then became the STEM (Scanning TEM). Naturally, there's a trade off between resolution, and areal coverage.

    That's STM you have in mind, not SEM.
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