6 Operating in CI Mode
To Set Up the Software for CI Operation
5977B Series MSD Operating Manual 149
To Set Up the Software for CI Operation
Procedure
1 From the Tune and Vacuum Control view, select Load Tune Parameters from
the File menu, and load the tune file PCICH4.U.
2 If CI autotune has never been run for this tune file, the software will prompt
you through a series of dialog boxes. Accept the default values unless you
have a very good reason for changing anything.
The tune values have a dramatic effect on MSD performance. Always start
with the default values when first setting up for CI, and then make
adjustments for your specific application. (See Table 13 for default values
for the Tune Control Limits box.) These limits are used by Autotune only.
They should not be confused with the parameters set in Edit MS
Parameters or with those appearing on the tune report.
Notes for Table 13:
•N/A: Not available. There are no PFDTD ions formed in PCI with any reagent
gas but methane, hence, CI autotune is not available with these
configurations.
Always verify GC/MSD performance in EI before switching to CI operation.
Table 13 Default Tune Control Limits, used by CI autotune only
Reagent gas Methane Isobutane Ammonia
Ion polarity Positive Negative Positive Negative Positive Negative
Abundance target 1x10
6
1x10
6
N/A 1x10
6
N/A 1x10
6
Peakwidth target 0.6 0.6 N/A 0.6 N/A 0.6
Maximum repeller 4 4 N/A 4 N/A 4
Maximum emission current,
µA
240 50 N/A 50 N/A 50
Max electron energy, eV 240 240 N/A 240 N/A 240
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