February 2010

Low Voltage Electron Microscopy - Wikipedia Entry

There is a rather informative entry on Wikipedia (Click Here) detailing the Low Voltage Electron Microscopy (LVEM) technique. The entry goes through the advantages and limitations of the technique. The most notable advantages of LVEM are increased contrast, the elimination of the heavy metal staining procedure, and the ability to have TEM, SEM and STEM in the same instrument. We are proud to say that the LVEM5 is currently the only Low Voltage Electron Microscope available commercially today.

Higher contrast

A substantial decrease of electron energy allows for a significant improvement of contrast of light elements. Comparison images show that decreasing the acceleration voltage from 80 kV to 5 kV significantly enhances the contrast of test samples. The improved contrast is a direct result of increased electron scattering associated with a reduced accelerating voltage.


LVEM brings an enhancement of imaging contrast nearly twenty times higher than for 100 kV. This is very promising for biological specimens which are composed from light elements and don’t exhibit sufficient contrast in classical TEMs.


Stain not required

The improved contrast allows for the significant reduction, or elimination, of the heavy metal negative staining step for TEM imaging of light elements (H, C, N, O, S, P). While staining is beneficial for experiments aimed at high resolution structure determination, it is highly undesirable in certain protein sample preparations, because it could destabilize the protein sample due to its acid pH and relatively high heavy metal concentration. The addition of stain to sectioned samples such as biological materials or polymers can also introduce imaging artifacts.


Multiple modes

At low voltages both transmission electron microscopy (TEM) and scanning electron microscopy (SEM) are possible on the same instrument. It is even possible to have the scanning transmission electron microscopy (STEM) as well. This is not possible on conventional electron microscopes since SEM and TEM are normally carried out at very different accelerating voltages.


For more details, please click through to the Wikipedia article (Click Here), or visit the LVEM5 homepage (Click Here)

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