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.
[...]
In the most common SEM mode,
secondary electrons emitted by atoms excited by the electron beam are detected using a secondary electron detector
[...]
Specimens are observed in high
vacuum in a conventional SEM, or in low vacuum or wet conditions in a variable pressure or environmental SEM, and at a wide range of
cryogenic or elevated temperatures with specialized instruments.
[...]
SEM samples have to be small enough to fit on the specimen stage, and may need special preparation to increase their electrical conductivity and to stabilize them, so that they can withstand the high vacuum conditions and the high energy beam of electrons. Samples are generally mounted rigidly on a specimen holder or stub using a conductive adhesive.
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