What are the benefits and drawbacks of using an electron microscope?
advantage:
1. High resolution, the resolution of the optical microscope is 0.2μm, and the resolution of the transmission electron microscope is 0.2nm, that is to say, the transmission electron microscope is magnified by 1000 times on the basis of the optical microscope.
2. Transmission electron microscopes are often used to observe the fine material structures that cannot be resolved by ordinary microscopes; scanning electron microscopes are mainly used to observe the morphology of solid surfaces, and can also be combined with X-ray diffractometers or electron energy spectrometers. Constitute electron microprobes for material composition analysis; emission electron microscopes are used for the study of self-emitting electron surfaces.
shortcoming:
1. In an electron microscope, samples must be observed in a vacuum, so live samples cannot be observed. With the advancement of technology, the environmental scanning electron microscope will gradually realize the direct observation of living samples;
2. When processing the sample, it may produce a structure that the sample does not have, which exacerbates the difficulty of analyzing the image afterwards;
3. Due to 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. Since the transmission electron microscope can only observe very thin samples, it is possible that the structure of the surface of the material is different from the structure inside the material;
6. For ultra-thin samples (less than 100 nanometers), the sample preparation process is complicated and difficult, and the sample preparation is damaged;
7. The electron beam may destroy the sample through collision and heating;
8. In addition, the purchase and maintenance prices of electron microscopes are relatively high.
