What is an electron microscope?
The electron microscope is a type of microscope that uses electrons rather than photons for display - as a conventional light microscope. Because electrons have a much smaller wavelength than photons, they provide much greater magnification. Electrons are small "satellites" that circulate the atomic core and carry electric charge - these particles are so small that they are often modeled in physics as points. Nevertheless, the light waves are much larger, for example, a wavelength of about 500 nanometers for green color.
The best optical microscopes only offer a sample enlargement of about 2000x, while some electron microscopes can increase the sample by 50 million times; On the other hand, it is more typical of 2 million times. It works on the limit of about 0.1 nanometers, allowing the observation of individual atoms on the surface. The electron microscope was invented in 1931, when the first working prototype was built by Ernst Russia and Max Knoll.ruska eventually won the Nobel Prize in Physics (1986) for his success.
existedThey hold four types of electron microscopes, the first two are the most common: transmission electron microscope (TE), scanning electron microscope (SEM), reflective electron microscope (REM) and scanning electron microscope (STEM).
The transmission electron microscope is an electron microscope as originally invented. Using a sample that is semi -transparent to electrons, the electron beam is burned directly through the sample. The receiver, on the other hand, measures the electron density at each individual point and compiles them into the image in the gray stage. This is a sample image.
The scanning electron microscope has a somewhat less resolution than the Tem, but is still the most popular variety of the electron microscope. As its name suggests, scanning Ectron Ectron scans the electron beam through the sample. Instead of analyzing the original beam for information about make -up sample pick up sensors secondaryelectrons released from the surface of the excitation sample from the primary beam. This sacrifices a certain resolution for a 3D image of the sample. This is more than a compromise and is therefore the most popular electron microscopes.
Most scanning electron microscopes are very expensive to purchase and maintenance. They require a stable high -level electricity source, vacuum pump and cooling coil. The samples must be prepared, usually by coating by a thin layer of conductive material such as gold.