The Scanning Electron Microscope

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The Scanning Electron Microscope

1. An SEM is a high essentially magnification microscope, which uses a focused scanned micron and submicron ranges. SEM generates high-energy electrons and focused on the specimen of the electron beam is scanned over the surface of the specimen in a motion similar to a television camera to produce a rasterized digital image. Electrons are speeded up in a vacuum until their wavelength is extremely short, only 100-1000 that of white light. Beams of these fast-moving electrons are focused on a sample and are absorbed or scattered by the specimen and electronically processed into an image. The primary electron beam interacts with the sample in several key ways as-
2. The primary electron generates low-energy secondary electrons, which tend to emphasize the topographic nature of the specimen. 
3. Primary electrons can be backscattered which produces images with a high degree of an atomic number constant. 
4. Ionized atoms can relax by electron shell transition, which leads to either X-ray emission or auger electron ejection. The X-rays emitted are characteristics of the elements in the top few of the samples and are measured by the EDS detector.

The Block Diagram of The Scanning Electron Microscope