Axis BTA 2100D Manual do Operador descarregar pdf (Página 204)

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Initially, you specify the mass window of ions to be stored. Because each mass

has a unique secular frequency at a given storage rf voltage, it is possible to

construct a waveform that does not include frequencies near the secular

frequencies of the ions to be stored. The resulting waveform consists of a

distribution of discrete frequencies with missing frequencies, called notches,

corresponding to the frequencies of the stored ions.

Modulation (the periodic increase, then decrease) of the storage rf increases and

decreases the secular frequencies of the ions in the trap. Thus, the unwanted

ions may be brought in and out of resonance with frequencies in the applied

supplemental waveform, so that unwanted ions are ejected and ions of interest

are selectively accumulated.

The figure below is a timing diagram of the SIS scan function. Ionization begins

when the electron gate is turned on and electrons enter the trap. At the same

time, the supplemental waveform (WF) is turned on, and ion ejection begins.

With the electron gate and waveform both turned on, the amplitude of the rf

trapping field is modulated to vary the secular frequencies. Application of the

waveform and rf field modulation continues for another cycle after the electron

gate is turned off. This ensures that all remaining unwanted ions are ejected.

SIS Scan-Function Timing Diagram

Selected Ion Storage (SIS) Parameters

NOTE: The Ion Trap must be calibrated for optimum performance. Do SIS

Calibration in the Tutorial Section before running any SIS methods.

Click on the Ion Preparation-SIS tab

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