What does sem mean

sem means: scanning electron microscope.

Scanning electron microscopy is a high-resolution microscope based on the principle of interaction between an electron beam and a sample. Unlike conventional optical microscopes, SEM uses an electron beam to scan the surface of a sample and obtains high-resolution images by detecting and recording the interaction signals between the electron beam and the sample.

SEMs have extremely high resolution and depth, allowing the surface morphology, structure, and composition of most materials and samples to be observed, and the images can be expanded to provide more detailed information. Its resolution is typically at the nanometer to sub-nanometer level, which is unmatched by traditional optical microscopes. At the same time, SEM can also perform a variety of analytical tests such as chemical composition analysis and surface morphology analysis.

SEM works by placing the sample on an SEM stage, scanning the sample surface with an electron beam generated by an electron gun, detecting and recording the signals from the electron-sample interaction, and converting them into an image through an electron lens and a fluorescent screen.

The SEM needs to work in a vacuum environment, and therefore the sample needs to be prepped by removing substances such as moisture and gases.

Advantages of Scanning Electron Microscope:

1, high resolution: compared with the traditional optical microscope, scanning electron microscope has a higher resolution. Generally speaking, the resolution of SEM can reach the nanometer to sub-nanometer level, which makes SEM can observe the finer structure and surface morphology.

2. A wider range of sample types can be observed: Compared to traditional optical microscopes, SEM can observe not only organic and inorganic materials, but also different types of materials such as semiconductors, ceramics and metals.

3. Capable of chemical analysis: SEM can also be used in conjunction with equipment such as an energy spectrometer (EDS or WDS) to analyze the chemical composition of the sample, which allows SEM to observe not only the surface morphology of the sample, but also the elemental distribution of the sample.

4. 3D Reconstruction: By scanning from different angles, SEM can reconstruct the sample in three dimensions, which makes the observation more intuitive and comprehensive.

5. Vivid display effect: Through SEM's imaging method (scanning the interaction signal between the electron beam and the sample), the SEM imaging effect is more vivid and intuitive, which not only can display the morphology of the sample surface, but also the microstructure and texture of the sample surface.