What are some of the advantages and disadvantages of the electron microscope?
advantage:
1. High resolution, the resolution of optical microscope is 0.2 μ m, and the resolution of transmission electron microscope is 0.2nm, which means that transmission electron microscope magnifies 1000 times on the basis of optical microscope.
2. Transmission electron microscopy is commonly used to observe fine material structures that cannot be distinguished by ordinary microscopes; Scanning electron microscopy is mainly used to observe the morphology of solid surfaces, and can also be combined with X-ray diffraction or electron spectroscopy to form electron microprobes for material composition analysis; Emission electron microscopy is used for the study of self emitting electron surfaces.
Disadvantages:
1. In an electron microscope, samples must be observed in vacuum, so live samples cannot be observed. With the advancement of technology, environmental scanning electron microscopy will gradually achieve direct observation of live samples;
2. When processing samples, structures that were not originally present in the sample may be generated, which increases the difficulty of analyzing the image in the future;
3. Due to its strong electron scattering ability, it is prone to secondary diffraction and other phenomena;
4. Due to the fact that it is a two-dimensional projection image of a three-dimensional object, sometimes the image is not unique;
5. Due to the fact that transmission electron microscopy can only observe very thin samples, it is possible that the structure of the material surface is different from the structure inside the material;
6. Ultra thin samples (below 100 nanometers), the sample preparation process is complex and difficult, and there is damage during sample preparation;
7. Electron beams may damage samples through collision and heating;
8. In addition, the purchase and maintenance prices of electron microscopes are relatively high.
