Why do some microscopes use electrons instead of photons?
In: Physics
Because they’re used to generate pictures of things that are extremely small. They are so small their qualities are smaller than the wavelength of light so it would not show up under a traditional microscope. You must bounce electrons off of them instead.
Because the wavelenth of a electrons is smaller then photons of visible light. The diffrence can be up to 100,000 times smaller. It is very had to detect anything smaller then the wavelength because the wave can pass around object, it is the same with waves on water as with microscope. Take a wooden beam in water and wave go around it withough a lot of distubace, but something larger can block the waves.
It work the same with light and the result is around 200nm is resolution of light microscope compared to around 0.1 nm for election microsopes. The diameter of a atom is around 0.1- 0.5 nm so election microscope can detect individual atoms. For visible light you need something that the order of 400-2000 atoms in diameter to spot it.
It is possible to have light with shorter wavelength, the problem is you get to the X-Ray and Gamma ray part of the spectrum, they tend to pass trough solid matter a lot more then visible light or electrons.
Let’s say you have 100 balls and you want to use them to look at the shape of an object.
If the object is a box and you use tennis balls, you’ll get a good idea of the shape of the box based on how the tennis balls bounce off the object.
If the object is a Lego block, the tennis balls won’t show a good picture because they’re too big.
You need to drop 100 beebees on the Lego to get a good picture.
The object you’re using to create the image has tu be much smaller than the object you’re intending to observe.
It’s all about resolution.
The width of a photon means the maximum resolution is limited at around X1500 before the edges of items blur into each other. https://youtu.be/saeAKYLXuKk
Electrons have a shorter wavelength than photons while having far less kinetic energy. It allows them to view smaller structures without damaging them. A microscope using a wavelength small enough to view individual atoms, would also be capable of ionizing those atoms.
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