Advanced Topic 931 of 1102 Analytical, Lab & Spectroscopy
Electron Microscopy
Uses electron beams to image structure at nanometre scale.
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In-depth explanation of Electron Microscopy
Electron microscopy uses a beam of electrons instead of light, and because electrons have very short wavelengths, a few picometres at accelerating voltages of 100 kV, it achieves resolution far beyond the optical limit. The transmission electron microscope (TEM) passes electrons through a very thin specimen to reveal internal structure, while the scanning electron microscope (SEM) rasters a focused beam over the surface and collects secondary electrons to show topography. Samples generally must be placed in a vacuum, so they are dried or frozen, and non-conducting specimens are often coated with a thin layer of metal. The technique is essential in materials science, biology and nanotechnology.
Going deeper: Electron Microscopy
Key ideas: De Broglie wavelength of electrons is about 1.23/sqrt(V) nm with V in volts, giving 0.0039 nm at 100 kV. Practical resolution is limited by lens aberrations to about 0.1 nm for TEM and 1 to 5 nm for SEM. Magnification up to millions is possible. Energy-dispersive X-ray analysis (EDX) on the same instrument gives elemental composition.
Common mistakes and connections: Students think the resolution is set by the electron wavelength alone, but lens aberrations dominate. Samples can be damaged by the beam, so images may show artifacts. SEM images are grey-scale and any colours are added afterwards. TEM needs sections thinner than about 100 nm. Related to wave-particle duality, resolution limits of light microscopy and nanomaterials characterization.
Visualization of Electron Microscopy
Electron wavelength falls to a few picometres at 100 kV or more, far below visible light, which is why electron microscopes resolve atomic detail. The interactive lesson shows this as a live animation or chart.
Worked example and use case
SEM images of pollen grains reveal the surface sculpturing of each grain in fine detail.
Frequently asked questions about Electron Microscopy
What is Electron Microscopy?
Uses electron beams to image structure at nanometre scale.
Is Electron Microscopy a beginner, intermediate or advanced topic?
Electron Microscopy is a advanced topic in Analytical, Lab & Spectroscopy. It builds on beginner and intermediate topics, so review those first if needed.
What should I learn before Electron Microscopy?
Study these earlier topics in Analytical, Lab & Spectroscopy first: Flame Photometry, ICP-MS, X-ray Crystallography.
What comes after Electron Microscopy?
The next topics in Analytical, Lab & Spectroscopy are Scanning Tunneling Microscopy and Gravimetric Analysis.
Can I practise Electron Microscopy with quizzes?
Yes. The interactive lesson includes a self-check question on Electron Microscopy, and the Analytical, Lab & Spectroscopy quiz draws on every topic in this area.
Where Electron Microscopy fits in Analytical, Lab & Spectroscopy
Electron Microscopy is topic 55 of 99 in Analytical, Lab & Spectroscopy.