My first work Brief Introduction of Transmission Electron Micros | Page 2

USES, so the theoretical resolution of the electron microscope (about 0.1 nm) is much higher
than that of the optical microscope (about 200 nm).
Transmission electron microscope (TEM), referred to as Transmission electron microscope [1],
is the accelerated and concentrated electron beam projected on a very thin sample, the
electron and the atom in the sample collision and change direction, resulting in solid Angle
scattering.The size of the scattering Angle is related to the density and thickness of the
sample, so different light and shade images can be formed, which will be displayed on the
imaging devices (such as fluorescent screen, film, and photosensitive coupling components)
after magnification and focusing.
Because the DE Broglie wavelength of the electron is very short, the resolution of the
transmission electron microscope is much higher than that of the optical microscope, which
can reach 0.1 ~ 0.2nm and the magnification is tens of thousands ~ millions of times.Thus,
transmission electron microscopy can be used to observe the fine structure of a sample, or
even the structure of a single column of atoms, tens of thousands of times smaller than the
smallest structure that can be observed with an optical microscope.TEM is an important
analytical method in many scientific fields related to physics and biology, such as cancer
research, virology, materials science, nanotechnology, semiconductor research and so on.
At a low magnification, the contrast of TEM imaging is mainly caused by different electron
absorption due to different thickness and composition of materials.When magnification
power is high, the complex wave action will cause the difference in the brightness of the
image, so professional knowledge is needed to analyze the obtained image.By using different
modes of TEM, the sample can be imaged by means of chemical properties of the substance,
crystal orientation, electron structure, electron phase shift caused by the sample, and
normal electron absorption.
The first TEM was developed by Max knorr and ernst lueska in 1931. The research team
developed the first TEM with a resolution beyond visible light in 1933, and the first
commercial TEM was successfully developed in 1939.
Large transmission electron microscope
Conventional TEM generally adopts 80-300kv electron beam acceleration voltage, different
models correspond to different electron beam acceleration voltage, and its resolution is
related to electron beam acceleration voltage, up to 0.2-0.1nm. High-end models can
achieve atomic-level resolution.
Low voltage transmission electron microscope
Low-voltage electron microscope (LVEM) USES a much lower electron beam accelerating
Voltage (5kV) than a large transmission electron microscope.The lower accelerating voltage
will enhance the strength of the electron beam and the sample, thus improving the contrast
and contrast of the image, especially suitable for polymer and biological samples.At the
same time, the damage of low voltage transmission electron microscope to the sample is