Devesh Parekh
Electron Microscopy
As the curiosity of scientists around the world increased, so did the demand for more advanced technology to meet their demands. The light microscope that had previously been more than sufficient was outdated due to its poor resolution. Photon particles were too large and therefore the resolution of light microscopes was not good enough. When the electron microscope which could look at 2 objects 2 nanometres apart clearly was invented, scientists found it a useful tool in furthering their knowledge of organisms.
There are two types of electron microscopes; the transmission microscope and the scanning microscope. The electron microscope cannot be used to look at living cells. This is because the atoms in organic molecules have a low atomic number so do not scatter electrons and also a high-intensity electron beam can destroy parts of the specimen, producing light coloured areas on the screen. There is a vacuum inside an electron microscope as beams of electrons have a very short wavelength and the flow of electrons is interrupted by molecules in air. The vacuum simply enables the microscope to a produce a clearer image. This can also be done by using electron magnets to focus the image onto a fluorescent screen. The resolving power of a microscope depends on the wavelength of the electromagnetic radiation used whilst increasing the magnification in electron microscopy results in an increase in the amount of visible detail. An image is formed from electrons emitted or reflected from the surface of a complete specimen where light areas on an electronmicrograph are produced when electrons have been able to pass through the specimen whilst electron dense areas scatter the electrons and produce dark areas on the electronmicrograph. Photographs of a specimen viewed with an electron microscope are called electronmicrographes.
