Stereo Scan 440 - DCU

6.
H an artefact is suspected as a result of a preparative procedure. a control
specimen should be utilised.
7. The speci~n stub should be in good elecbical contact with ground
potential.
8
There should be good elecbical contact between the surface of the
specimen and the specimen stub, ie attach sample to stub with
conducting paint such as Silver-Dag and coat the specimen adequately if
necessary .
.8
9. The speci~n stub should give rise to as few backscattered and
secondary electrons as possible. Aluminium stubs are normally used,
although carbon stubs are used for some X-ray microanalysis
applications.
10. Very small particles are best mounted on a low mass foil to give rise to
minimal background signals. eg nylon film stretched over an aluminium
ring.
11 The sample must be attached to the s~n holder (stub) so that it
does not move whilst being irradiated by the electron beam.
12, The sample should be attached to the specimen holder (stub) so that all
the surface can be studied using the existing stage movements (eg tilt,
rotate, X, Y, Z).
-
Conductors
These fall into two groups:-
Non-Conductors
Metallic: these are generally excellent conductors and need no
preparation
. Semi-conducting samples with a resistance of less than
10-10 ohms can be examined without special preparation
This group includes all samples which are not electrically conducting, eg dIOse
generally not containing volatiles, eg fibres, plastics, polymers, semi-conductors
with a resistance greater than about 10-10 ohms.
Those generally containing volatiles, eg biological and tKJtanical material
Stereoscan 440 Operator Manual