Introduction to the principles, advantages, and application areas of scanning electron microscopy
Scanning electron microscope is capable of observing the morphology and structure of the surface of the samples with very high resolution, which is one of the powerful tools for the research of materials related workers and scholars. Its application scope is so wide that it can even be extended to biological, medical and industrial fields. In this article, the principle, characteristics, advantages and classification of scanning electron microscope will be comprehensively introduced, so that you can better understand the scanning electron microscope.
Working Principle of Scanning Electron Microscope
Scanning electron microscopes are based on the properties of electrons. They use a focused electron beam instead of the visible light found in traditional optical microscopes. They use a high-speed electron beam to interact with electrons on the surface of the sample, causing electron emission. These emitted secondary electrons are detected by a detector. It is received and converted into a higher resolution and more detailed image.
A scanning electron microscope consists mainly of an electron gun, a focusing system, a scanning coil, a sample stage and a detector. The electron gun generates an electron beam which is then focused on a very small area by the focusing system. Controlled by the scanning coil, it interacts with the atoms and molecules in the sample as it sweeps across the sample surface, generating signals. These signals are captured by the detector and then processed by a signal processor and finally converted into a high quality image.
Features and advantages of scanning electron microscope
1. High resolution: Scanning electron microscopes have very high resolution and can observe a wide range of details such as the structure and surface morphology of tiny samples. The latest scanning electron microscope secondary electron imaging resolution has reached 3 ~ 4nm.
2. High magnification: Scanning electron microscopes are capable of high magnification observation. Magnification can range from a few times in situ to around 200,000 times, allowing microstructures to be clearly presented.
3. Non-contact observation: Unlike transmission electron microscopes, scanning electron microscopes use non-contact observation, which does not damage the shape and structure of the sample.
4. Increased Depth: Scanning Electron Microscope can scan and analyse at different depths, enabling us to observe the internal structure of samples which cannot be shown by traditional microscopes. It can be used for direct observation and microfracture analysis. Therefore, most microfracture analysis work is now done using scanning electron microscopy.
5. Three-dimensional reconstruction: By acquiring images of the specimen from all angles, the scanning electron microscope can carry out three-dimensional reconstruction to provide more comprehensive information.
6. Digital processing: Digital processing and analysis of scanning electron microscope images improves the accuracy and reliability of observation and analysis. It can be used in conjunction with energy spectrometers, charge-coupled devices (CCDs), and so on. To carry out chemical composition analysis, energy spectrum analysis and so on.
Scanning electron microscope application areas
1. Material science: Scanning electron microscope can help researchers observe the microstructure of materials and analyse their composition and surface morphology. This is very important for the research and development of new materials, improvement of material properties and quality control.
2. Life Science: SEM is also widely used in biology and can help to study the structure of cells and tissues, the morphology and ecology of microorganisms etc.
3. Nanotechnology: The high resolution and sensitivity of scanning electron microscope make it an important tool for research in the field of nanotechnology. Through SEM, scientists can observe the structure and morphology of nanoscale substances, and adjust and optimise the properties of nanomaterials.
4. Energy field: Scanning electron microscope is widely used in the research of energy fields such as solar cells, fuel cells, electronic devices and so on. It helps scientists to observe defects or inhomogeneities in the microstructure and optimise material properties.
