What are the advantages and disadvantages of electron microscope?
Advantages:
1. The resolution is high. The resolution of the optical microscope is 0.2μm, and that of the transmission electron microscope is 0.2nm, which means that the transmission electron microscope is magnified 1000 times on the basis of the optical microscope.
2. Transmission electron microscope is often used to observe the fine material structure that can't be distinguished by ordinary microscope; Scanning electron microscope (SEM) is mainly used to observe the morphology of solid surface, and can also be combined with X-ray diffractometer or electron energy spectrometer to form electron microprobe for material composition analysis. Study on self-emitting electron surface by emission electron microscope.
Disadvantages:
1. In the electron microscope, the sample must be observed in vacuum, so it is impossible to observe the living sample. With the development of technology, environmental scanning electron microscope will gradually realize the direct observation of living samples;
2. When the sample is processed, the structure that the sample does not have may be generated, which aggravates the difficulty of analyzing the image afterwards;
3. Because of the strong electron scattering ability, secondary diffraction is easy to occur.
4. Because it is a two-dimensional plane projection image of a three-dimensional object, sometimes the image is not unique;
5. Because the transmission electron microscope can only observe very thin samples, it is possible that the structure on the surface of the material is different from the structure inside the material;
6, ultra-thin samples (below 100 nanometers), the sample preparation process is complex and difficult, and the sample preparation is damaged;
7. The electron beam may damage the sample through collision and heating;
8. In addition, the price of purchasing and maintaining the electron microscope is relatively high.
