Tuning in FD mode 9-27
Tuning in FD mode
When working in FD mode, you must first obtain a beam using the reference
sample, and tune the ion source. Once the instrument is tuned, you can
introduce the sample onto the emitter. Using the probe ramp, the emitter
current is ramped and you can run an experiment.
In FD ionization the sample is loaded directly onto the emitter, typically
10 µm tungsten wire covered with carbon microneedles. An electric current is
passed through the emitter wire to raise the temperature. The sample is
ionized on the surface of the emitter wire or, the sample can volatilize before
ionization occurs.
Obtaining a beam in FD operation
Using this procedure, obtain a beam using a reference sample, before you
inject sample onto the FD emitter. You need to use a 10 mm FD emitter for
this procedure.
See also: Changing an emitter on page 10-33.
To obtain a beam in FD operation:
1. In the MassLynx Tune window, click Ion Mode > FD.
2. Use a septum-piercing syringe to introduce approximately 3 µL of
chloropentafluorobenzene or acetone into the reference reservoir.
3. In the FD Source tab Emitter Current, Extraction Voltage, and Heater
Current, type zero.
4. Click .
5. In the Tuning Setup dialog box, set the Scan Time(s) to 1.2 and the Inter
Scan Delay (s) to 0.2
6. In Data pane, click Continuum from the Data Format list.
Caution: Monitor the readback of the Current Leakage. If the
current leakage rises above 10 µA constant readback, there is
excessive current leakage to ground and indicates the source is
dirty.
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