The Scanning Electron Microscope

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-
The primary electron generates low-energy secondary electrons, which tend to emphasize the topographic nature of the specimen.
Primary electrons can be backscattered which produces images with a high degree of an atomic number constant.
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

Durgam Vigyan Sansthana