ZEISS
5 First Operating Steps | 5.7 Working with Specific Specimen Types
6. Adjust the imaging parameters.
INFO:
The parameters depend on the type of specimen being examined and the nature of
the detail you are expecting to see.
It is recommended to start with:
EHT = 20 kV
I Probe = 400 pA or higher
Chamber pressure = 650 Pa
Peltier temperature = 1 °C
WD = 6.0 mm
Detector = BSD or C2DX
7. Center and focus a distinguishable feature on the specimen.
5.7.3.6 Adjusting Operating Parameters
Procedure
1. Increase the pressure to 550 Pa and keep the temperature constant at 1 °C.
2. Increase the pressure in steps of 20 Pa and review the image.
à
The water droplets start to appear around 600 Pa.
3. Once the water droplets are clearly visible on the stub, make a note of the pressure.
INFO:
The rate of water condensation from the chamber on the stub and the evaporation
of the droplets from the stub to the chamber should be at equilibrium.
4. In the
Purge Control
window, set
Purge Min
to the pressure value obtained in the previ-
ous step.
5. Set
Purge Max
to a pressure value that is around 100 Pa higher than the
Purge Min
value.
6. Adjust the
Purge Cycle
to 3.
7. Vent the chamber without changing any of the parameters.
8. Remove the plain stub and dry the area underneath the stub on the Peltier coolstage.
9. Carefully install the specimen on a new stub, place and tighten the stub on the Peltier cool-
stage.
10. Use a pipette for putting a few droplets of distilled water on the Peltier coolstage holder.
INFO:
Do not put any water droplets on the stub or directly on the specimen as the water
droplets can cover the specimen surface and prevent viewing the areas of interest.
11. Move the Peltier coolstage slightly to the right or left of the chamber before closing the
chamber door.
This prevents any droplets splattering up on the C2D, BSD, or the objective lens area during
the pump down process.
12. Close the chamber door and pump down the system.
13. Switch on the beam.
14. Use the stage navigation to position the specimen under the beam.
INFO:
Use the
Stage Navigation Bar
or the chamberscope to monitor the stage move-
ment.
15. If necessary, increase the pressure, but in very small steps.
INFO:
If you increase the pressure in large steps, water can accumulate on the specimen
and prevent imaging.
16. If necessary, adjust the humidity level to achieve 100 % humidity.
INFO:
This changes both the Peltier temperature and the chamber pressure.
17. If necessary, increase the EHT.
INFO:
This increases the signal strength but can damage the specimen.
18. If necessary, reduce the spot size.
INFO:
This provides higher resolution but means loss of signal.
19. If necessary, reduce the WD.
INFO:
This increases the signal strength but reduces the field of view, which means that a
montage of specimen images may be required.
Instruction Manual ZEISS EVO | en-US | Rev. 10 | 354706-0780-006
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