Why is electron microscopy's resolution higher than that of optical microscopy?
The magnification of an optical microscope is smaller than that of an electron microscope. An optical microscope can only observe microscopic structures such as cells and chloroplasts, while an electron microscope can observe submicroscopic structures, such as the structure of organelles, viruses, bacteria, etc
An electron microscope projects an accelerated and aggregated electron beam onto a very thin sample, causing electrons to collide with atoms in the sample and change direction, resulting in stereo angular scattering. The size of the scattering angle is related to the density and thickness of the sample, so it can form images with different shades. The images will be displayed on imaging devices (such as fluorescent screens, films, and photosensitive coupling components) after amplification and focusing.
Due to the very short de Broglie wavelength of electrons, the resolution of transmission electron microscopes is much higher than that of optical microscopes, reaching 0.1-0.2nm and magnification of tens of thousands to millions of times. Therefore, the use of transmission electron microscopy can be used to observe the fine structure of samples, and even to observe the structure of only one row of atoms, which is tens of thousands of times smaller than the smallest structure that can be observed under an optical microscope. TEM is an important analytical method in many scientific fields related to physics and biology, such as cancer research, virology, materials science, as well as nanotechnology, semiconductor research, and so on.
