In the electron microscope the samples are exposed to extreme conditions. They have to conform to special requirements to obtain images of good quality and adequate contrast.
In order for the electron beam to pass the sample the transmission electron microscopy (TEM) requires a very thin sample, free of water and with a very high intrinsic contrast. On the other hand the sample has to be stable enough for the electron beam not to force changes in the object during observation.
For the examination of surfaces with the scanning electron microscopy (SEM) the electron beam does not have to pass trough the sample. However it has to be water-free and electrically conductive.
Biological samples do not fulfill the above-mentioned preconditions. They therefore have to be prepared with special preparation techniques to maintain their ultra structure. In our service laboratory we offer the following preparation techniques.
||conventional preparation techniques
- chemical fixation
- embedding and ultra thin sectioning
- critical-point drying
- negative stain
- jet freezing
- immersion freezing (standard freezing)
- freeze fracture followed by freeze etch and replication
- room temperature shadowing (Pt, Pt/C, Ta/W, Au, Ag)
- low temperature shadowing (Pt, Pt/C, Ta/W, Au, Ag)
- low angular and rotation shadowing