Why is the resolution of an electron microscope higher than that of a light microscope?
The magnification of the optical microscope is smaller than that of the electron microscope. The optical microscope can only observe microstructures, such as cells and chloroplasts, while the electron microscope can observe submicroscopic structures, that is, the structure of organelles, viruses, bacteria, etc.
The electron microscope projects an accelerated and concentrated electron beam onto a very thin sample, and the electrons collide with the atoms in the sample to change their direction, thereby producing solid angle scattering. The size of the scattering angle is related to the density and thickness of the sample, so images with different brightness and darkness can be formed, and the images will be displayed on imaging devices (such as fluorescent screens, films, and photosensitive coupling components) after zooming in and focusing.
Due to the very short de Broglie wavelength of the electron, the resolution of the transmission electron microscope is much higher than that of the optical microscope, which can reach 0.1-0.2nm, and the magnification is tens of thousands to millions of times. Therefore, the use of transmission electron microscopy can be used to observe the fine structure of samples, even the structure of only a single column of atoms, which is tens of thousands of times smaller than the smallest structure that can be observed by optical microscopy. 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, etc.
