Characteristics of Electron Microscopes and Differences Between Several Microscopes
The resolution of the electron microscope is very high, and it is more useful for the study of colloidal particles. Modern electron microscopes can resolve small molecules of 1nm, so it can cover the entire colloidal range and can directly reflect the size and shape of particles. At present, electron microscopy is usually used to study the morphology of nanomaterials . The characteristics of several electron microscopes are compared in the table. The principle of the electron microscope will not be repeated here.
| Electron microscope type | resolution | working environment | Sample ambient humidity | The degree of damage to the sample | Detection depth |
| Scanning Tunneling Electron Microscopy | Atomic level (vertical 0.01nm; lateral 0.1nm) | Real environment, atmosphere, solution, vacuum | room temperature or low temperature | none | 1~2 atomic layers |
| scanning electron microscope | Point resolution (0.3~0.5nm ) Lattice resolution (0.1~0.2nm) | high vacuum | room temperature | Small | Close to SEM, but actually limited by the thickness of the sample, generally less than 100nm |
| Transmission Electron Microscopy (TEM) | 6~10nm | high vacuum | room temperature | Small | 10nm (at 10 times) 1μm (1000 times) |
The biggest advantage of electron microscopy is that it can provide direct information on the characteristics of particle shape, surface morphology and texture. The main problem in its quantitative determination of the size of dispersed particles is to ensure that the results are representative of the entire sample, and how to obtain a satisfactory measurement when the dispersed particles have irregular shapes. It is necessary to examine several samples and measure a large number of dispersed particles. The required number of samples and measurements can only be based on statistical data variability.
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