Transmission electron microscopy (TEM) is a type of electron microscopy that uses a beam of electrons to create highly magnified images of the internal structure of a sample. TEM involves passing the electron beam through a thin section of the sample, which allows for the creation of a detailed image of the sample’s internal structure.
The basic steps involved in TEM are as follows:
- Sample preparation: In order to be imaged by TEM, a sample must be prepared in a specific way. This involves cutting a thin section of the sample, typically less than 100 nanometers thick, and mounting it on a support grid.
- Electron beam generation: An electron beam is generated in the electron source and accelerated through a series of electromagnetic lenses.
- Illumination of the sample: The electron beam is focused onto the thin section of the sample, which is placed in the path of the beam. The electrons that pass through the sample are scattered or absorbed by the atoms in the sample.
- Collection of the transmitted electrons: The transmitted electrons are collected by a detector, which can be either a fluorescent screen or a digital camera. The collected electrons create an image of the sample’s internal structure.
- Image processing: The collected electron signals are processed by computer software to create a final image. This may involve adjusting the contrast, brightness, and other parameters of the image.
TEM can provide very high-resolution images, allowing for the visualization of individual atoms in some cases. It is widely used in many fields of science, including materials science, biology, and physics. In materials science, TEM can be used to study the structure and properties of materials at the nanoscale, while in biology, it can be used to study the structure of cells, viruses, and other biological structures.