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.
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)