The Applications and Key Features of Transmission Electron Microscopes
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 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 electron beams instead of light beams. The Talos series transmission electron microscope equipped in Jifeng Electronics MA Laboratory uses ultra-high brightness electron guns, while the spherical aberration transmission electron microscope HF5000 uses cold field electron guns.
2. Vacuum system
In order to avoid 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. Usually, 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 those 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. Like a 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) cameras. When the electron beam interacts with the fluorescent screen on the image plane, visible light is generated, forming a projected image of the sample, which is commonly used for searching for samples. Due to the fact that fluorescent screens need to be used in a dark room environment and are not user-friendly, manufacturers now install a camera above the fluorescent screen side, allowing TEM operators to observe the display in a bright environment to search for samples, tilt the belt axis, and perform other operations. This inconspicuous improvement is the basis for achieving human-machine separation.
7. Form an image
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 Explanation
By observing and analyzing images, researchers can understand the microstructure information of the sample, such as crystal structure, lattice parameters, crystal defects, atomic arrangement, etc. Jifeng has a professional material analysis team that can provide customers with full process analysis solutions and professional material analysis reports.
