Electron Microscopy (EM) is an advanced imaging technique that uses a beam of electrons instead of light to achieve high-resolution magnification of specimens. It is widely used in materials science, nanotechnology, biology, and metallurgy to analyze microstructures at the nanometer and atomic scales.
Unlike optical microscopes, which use visible light waves, electron microscopes use electron beams with much shorter wavelengths.
Due to their shorter wavelength, electrons provide much higher resolution than optical microscopes.
Electromagnetic lenses (coils) focus the electron beam instead of glass lenses.
The interaction of electrons with the sample generates various signals used to form an image.
πΉ Function: Provides detailed surface images of specimens.
πΉ How It Works:
A focused electron beam scans the surface of the specimen.
The interaction of electrons with the sample generates secondary electrons and backscattered electrons.
A detector captures these signals to form a 3D image of the surface.
πΉ Applications:
Surface morphology of metals, ceramics, polymers.
Failure analysis and fracture examination.
Biological specimen imaging (e.g., bacteria, cells).
πΉ Function: Provides ultra-high-resolution images of internal structures.
πΉ How It Works:
An electron beam passes through an ultra-thin sample (~100 nm).
The transmitted electrons form an image based on how much the sample absorbs electrons.
The image is magnified using electromagnetic lenses.
πΉ Applications:
Crystallographic studies of metals and semiconductors.
Analysis of nanoparticles and biological structures (viruses, proteins).
Defect analysis in materials science.
Combines features of SEM and TEM.
Uses a scanning electron beam while transmitting electrons through the sample.
Used for high-resolution imaging and chemical analysis.
β Higher resolution than optical microscopes (up to atomic level).
β Greater depth of field (SEM provides 3D-like images).
β Elemental analysis using X-ray detectors (Energy Dispersive Spectroscopy - EDS).
β Requires a vacuum environment (electrons cannot travel through air).
β Specimens need special preparation (coating, ultra-thin slicing for TEM).
β Expensive and requires trained personnel.
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Material Science β Microstructural analysis of metals, ceramics, and polymers.
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Nanotechnology β Imaging nanoparticles, carbon nanotubes, and quantum dots.
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Biomedical Research β Virus and cell imaging, tissue analysis.
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Forensic Science β Trace evidence analysis (gunpowder residues, fibers).