Zeiss Focal CC, Инструкция по эксплуатации

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5 First Operating Steps | 5.6 Controlling the Gas Injection ZEISS
2. In the SmartSEM Status dialog, double click
on CC Type = Focal CC .
3. For GeminiSEM: In the GeminiSEM Control panel, select the Control tab.
For Sigma: In the SEM Controls panel, select the Vacuum tab.
4. In the Charge Compensation section, click on
On .
à
The Focal CC is ready for N₂ injection.
à
At startup, the CC Pressure is at 0 % .
à To inject N₂ refer to Controlling the Gas Injection [
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20] .
à
If the quiet vacuum mode (optional) is activated, the quiet vacuum mode switches off
and the backing pump starts.
5.6 Controlling the Gas Injection
You can regulate the amount of injected gaseous nitrogen between 1 % and 100 % CC pressure.
100 % corresponds to a system vacuum of 7 × 10⁻³ mbar. The amount of gaseous nitrogen that
you have to inject depends on both, the charge injection to the specimen (EHT, aperture, beam
current, magnification (field of view), and pixel density), and how much material the ultramicro-
tome cuts away for each fresh image to be acquired. The charge present on the specimen is also
a strong function of the local insulation properties. Empty resin areas normally show much more
charging effects than those containing heavy metal staining. The ability to compensate charge is
therefore a complex mix of the amount of immobile electrons resident in the near surface region,
but also the ionization process of the local N₂ cloud.
This procedure consists of the following steps:
1. Starting the Gas Injection [
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2. Stopping the Gas Injection [
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5.6.1 Starting the Gas Injection
Info
For Sigma series microscopes the SE detector is automatically switched off, if the amount of in-
jected gaseous nitrogen is above 50 % CC pressure. This prevents arcing at the SE detector.
The automatic switch off requires SmartSEM 6.06 or later. If you use SmartSEM 6.05 or earlier,
you have to turn down the HT bias to the SE detector manually when the Focal CC is on.
Prerequisite ü The Focal CC is selected in the software, refer to Selecting Focal CC in the Software [
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19] .
ü
The nozzle is pointing directly at the specimen. If correctly located, the edge of the nozzle is
always visible in low magnification SEM images when the BSE detector is retracted.
Procedure 1. For GeminiSEM: In the GeminiSEM Control panel, select the Control tab.
For Sigma: In the SEM Controls panel, select the Vacuum tab.
20 Instruction Manual ZEISS Focal CC | en-US | Rev. 2 | 349561-8021-000