Electron beams are capable of providing crystallographic information about nanoparticle surfaces and can also be used to produce images of the surface, and they play this role in electron microscopes.
The Operation of Transmission Electron Microscope
In a transmission electron microscope the electrons from a source such as an electron gun enter the sample. They are scattered as they pass through it. They are then focused by an objective lens, amplified by a magnifying (projector) lens and finally produce the desired image.
The wavelength of the electrons in the incident beam is given by:
Where the energy acquired by the electrons is E = eV and V is the accelerating voltage expressed in kilovolts.
The transmission electron microscope can form images by the use of the selected area electron diffraction (SAED) aperture located between the objective and projector lenses. The main part of the electron beam transmitted by the sample consists of electrons that have not undergone any scattering. The beam also consists of electrons that have lost energy through inelastic scattering with no deviation of their paths, and electrons that have been reflected by various crystallographic planes.
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