Electron microscopy makes use of electrons to produce high resolution images of specimens. In transmission electron microscopy, a beam of electrons is transmitted through an ultra-thin specimen to produce a high resolution image on a fluorescent screen or on photographic film. The resolution of the image obtained is in the nanometer range.

We will go through various aspects of transmission electron microscopy in this article.

A transmission electron microscope works almost in the same way as a slide projector does. The only difference is that a focused beam of electrons is used in the former in contrast to light used in the latter. This beam of electrons is generated by passing electricity through a tungsten filament. Field emission can also be utilized to do this. The acceleration of electrons is facilitated by an electrical potential.

The beam of accelerated electrons is then focused onto the specimen by use of electrostatic and electromagnetic lenses. After passage through an ultra-thin specimen, the electron beam is projected through a lens on to a fluorescent screen. On the screen a high resolution image of the specimen can be viewed.

The illuminated areas of the image correspond to those that have been hit by electrons which have passed through those areas of the specimen at which the electrons did not strike any solid material. The dark areas of the image correspond to those areas of the specimen, through which electrons could not pass through at all. At such points on the specimen, electrons have struck atoms of the specimen material and have been scattered.

An ultra thin layer of the specimen, only some hundreds of nanometers thick, is first prepared properly, before being mounted on the microscope platform.

Specimen preparation entails drying it, embedding the specimen in plastic, and then coating it with gold or carbon, to facilitate conduction of electrons. The specimen is also stabilized. Further, the entire microscope assembly unit, inclusive of the specimen, is placed under vacuum to prevent the focused electron beam from getting scattered by air molecules. Cryogenic specimen preparation helps in better output.

It should be remembered that in transmission electron microscopy vibration ruins the output. The whole microscope unit should be placed on the ground level to avoid influence of mechanical vibration on the image output. The site should be chosen to completely avoid mechanical vibration.

The transmission electron microscope was invented by two German scientists, Max Knoll and Ernst Ruska, in 1931.

Transmission electron microscopy cost depends on many factors and is quite high.

You can search the Internet to know about transmission electron microscopy courses as a career option.

Application of transmission electron microscopy and transmission electron microscopes is in many areas. It includes TFT transistor failure analysis, cytology, cancer detection, metallurgical examination, histology, silicon chips manufacture, morphology, and genetic engineering.

Transmission electron microscopy was the initial stage of electron microscopy. It can only produce a silhouette image. Scanning electron microscopy is much more useful.