What are the advantages and disadvantages of electron microscopy?
Advantages:
1, high resolution, the resolution of the optical microscope is 0.2μm, the resolution of the transmission electron microscope is 0.2nm, that is to say, the transmission electron microscope in the optical microscope on the basis of the magnification of 1000 times.
2, transmission electron microscope is often used to observe those with ordinary microscopes can not distinguish the fine structure of the material; scanning electron microscope is mainly used to observe the morphology of solid surfaces, but also with the X-ray diffractometer or electron spectrometer combined, constituting the electron microprobe, used for the analysis of the composition of the material; emission electron microscope for the study of the surface of the self-emission of electrons.
Disadvantages:
1, in the electron microscope samples must be observed in a vacuum, so it is not possible to observe live samples. With the progress of technology, environmental scanning electron microscopy will gradually achieve direct observation of live samples;
2, The processing of the sample may produce structures that were not originally present in the sample, which exacerbates the difficulty of analysing the image thereafter;
3, due to the extremely strong electron scattering ability, prone to secondary diffraction and so on;
4, due to the two-dimensional plane projection image of three-dimensional objects, sometimes the image is not unique;
5, because the transmission electron microscope can only observe very thin samples, and it is possible that the structure of the surface of the material is different from the internal structure of the material;
6, ultra-thin samples (below 100 nm), the sample preparation process is complex and difficult, and there is damage to the sample preparation;
7, the electron beam may damage the sample by collision and heating;
8, in addition to the electron microscope purchase and maintenance of the price is relatively high.
