Applications and characteristics of Transmission electron microscopy
Transmission electron microscopy (TEM) is a high-resolution microscope used to observe the internal structure of samples. It utilizes an electron beam to penetrate the sample and form a projected image, which is then interpreted and analyzed to reveal the microstructure of the sample.
1. Electronic source
TEM uses an electron beam instead of a beam of light. The Talos series transmission electron microscope equipped by Jifeng Electronic MA Laboratory uses an ultra-high brightness electron gun, while the HF5000 spherical aberration transmission electron microscope uses a cold field electron gun.
2. Vacuum system
To avoid the interaction between the electron beam and the gas before passing 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 ranges from nanometers to submicrons. Jifeng Electronics is equipped with dozens of Helios 5 series FIBs for preparing high-quality ultra-thin TEM samples.
4. Electronic transmission system
The electron beam is focused through a transmission system. These lenses are similar to lenses in optical microscopes, but due to the much shorter wavelength of electrons compared to light waves, the design and manufacturing requirements for lenses are higher.
5. Image plane
After passing through the sample, the electron beam enters an image plane. On this plane, the information of the electron beam is converted into an image and captured by the detector.
6. Detector
The most common detectors are fluorescent screens, CCD (charge coupled device) cameras, or CMOS (complementary metal oxide semiconductor device) cameras. When an electron beam interacts with a fluorescent screen on the image plane, visible light is generated, forming a projected image of the sample, which is commonly used to locate the sample. Due to the need for fluorescent screens to be used in a dark room environment, which is not user-friendly for user operation, current manufacturers will install a camera above the side of the fluorescent screen, allowing TEM operators to observe the display in a bright environment for searching for samples, tilting the belt shaft, and other operations. This inconspicuous improvement is the foundation for achieving human-machine separation.
7. Image formation
When the electron beam passes through the sample, it interacts with the atoms and crystal structure inside the sample, scattering and absorbing. Based on these interactions, the intensity of the electron beam will form an image on the image plane. These images are all two-dimensional projection images, but the internal structure of the sample is often three-dimensional, so special attention should be paid to this when analyzing the detailed information inside the sample.
8. Analysis and Interpretation
By observing and analyzing the images, researchers can understand the sample's crystal structure, lattice parameters, Crystallographic defect, atomic arrangement and other microstructure information. Ji Feng has a professional material analysis team that can provide customers with full process analysis solutions and professional material analysis reports.
