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Collector slit plate assembly
Z Restrictor 4 plate
The Z Restrictor 4 plate is operated by a pneumatically controlled valve that
steps the plate in the Z plane and restricts the ion beam for very high
resolution mode. The plate is controlled by Z4 Restrictor on the Tune window's
Control 2 tab.
Rotate 4 lens
The Rotate 4 lens is used to rotate the ion beam before it passes through the
collector slit. It is controlled by Rotate 4 on the Tune window's Lenses 2 tab.
Collector slit
The adjustable collector slit is located immediately before the detector
assembly. It defines the ion beam width in the Y plane. The collector slit is
controlled by Collector Slit on the Tune window's Control 1 tab.
When the slit is fully open, flat-topped peaks will appear, because the collector
slit is set to be wider than the ion beam, which scans across the slit.
Optimum transmission is achieved when the width of the collector slit is equal
to the ion beam width. When this is the case, the ion beam is said to be
triangulated. If the collector slit is closed further, such that it is narrower
than the ion beam, then the collector slit is said to be over-triangulated. This
gives the impression of higher resolution but this is misleading, because
apparently resolved masses could interfere with each other during an SIR
analysis.
The
figure "Flat-topped, correctly triangulated, and over-triangulated ion
beams" on page G-9
flat-topped, one where the collector slit is correctly triangulated, and one
where the collector slit is over-triangulated.
G-8
Theory and principles of operation
shows three tuning conditions: one where the ion beam is
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Troubleshooting
