The
Hitachi S-2460N is equipped with dual viewing modes, NSEM and SE. Will
in the NSEM mode it is possible to view samples that are moist and unfixed.
The SE mode is reserved for fixed, dehydrated and sputter coated samples.
NSEM:
In this mode you are using the Robinson detector to view only "backscatter"
electrons and the observation of secondary electrons is not possible.
The Robinson detector is inserted into the field (you can see it with
the camera) in order to detect the straight shooting "backscatter"
electrons. Imaging with backscattered electrons provides different information
from the specimen (usually beneath the surface) to the secondary electron
detector (the actual surface).
One can view samples with no initial preparation. The sample should
be as small as possible. Evacuation (which is adjustable and usually
set to a low vacuum) and viewing should be carried out promptly
SE:
In this mode you are using the normal collector to view all the secondary
electrons and few of the "backscatter" electrons. The Robinson
detector is moved out of the way for this mode, and the vacuum is set
to the highest setting.
This mode requires that the sample is "fixed" in formaldehyde
or glutaraldehyde, dehydrated through an alcohol series (0 to 100%),
critical point dried (or treated with HMDS) and sputter coated with
gold.