Uses and features of transmission electron microscopyUses and features of transmission electron microscopy
A transmission electron microscope (TEM) is a high-resolution microscope used to observe the internal structure of a sample. It uses an electron beam to penetrate a sample and form a projected image, which is then interpreted and analysed to reveal the microstructure of the sample.
1. Electron Source
TEM uses an electron beam rather than a light beam. The transmission electron microscope Talos series equipped by Jifeng Electronics MA Lab uses an ultra-high brightness electron gun, and the spherical aberration transmission electron microscope HF5000 uses a cold field electron gun.
2.Vacuum System
In order to avoid the electron beam interacting with the gas before travelling through the sample, the entire microscope must be maintained under high vacuum conditions.
3. Transmission sample
The sample must be transparent, meaning that the electron beam can penetrate it, interact with it and form a projected image. Typically, the thickness of the sample is in the nanometre to sub-micron range. Quarterly is equipped with dozens of Helios 5 series FIBs for the preparation of high quality ultra-thin TEM samples.
4. Electron Transmission System
The electron beam is focused through a transmission system. These lenses are similar to those used in optical microscopes, but because electron wavelengths are much shorter than light waves, the design and manufacture of the lenses is more demanding.
5. Image Plane
After passing through the sample, the electron beam enters an image plane. In this plane, the information from the electron beam is converted into an image and captured by a detector.
6. Detector
The most common detectors are phosphor screens, CCD (Charge Coupled Device) cameras or CMOS (Complementary Metal Oxide Semiconductor) cameras. When an electron beam interacts with a phosphor screen in the image plane, visible light is produced, resulting in a projected image of the sample, which is often used to find the sample. Since the phosphor screen needs to be used in a dark room environment, which is not user-friendly, manufacturers nowadays install a camera on the side of the phosphor screen, so that the TEM operator can observe the monitor in an open environment to find samples, tilt the tape axis and other operations, this inconspicuous improvement is the basis of the realisation of the separation of the man-machine.
7. Image Formation
As the electron beam passes through the sample, it interacts with the atomic and crystalline structures within the sample, scattering and absorbing. Based on these interactions, the intensity of the electron beam will form images on the image plane. These images are two-dimensional projected images, but the internal structure of the sample is often three-dimensional, so particular attention should be paid to this when resolving information about the internal details of the sample.
8. Analysis and Interpretation
By observing and analysing the images, researchers can understand the crystal structure, lattice parameters, crystal defects, atomic arrangement and other microstructural information of the sample. Jifeng has a professional material analysis team, which can provide customers with full-process analysis solutions and professional material analysis reports.
