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Characterization of Mobility-Dependent Ion Confinement in Rotating Electric Fields
Jung Yun Lee1, Sandilya V B Garimella1, Randolph V Norheim1
1Biological Sciences Division, Pacific Northwest National Laboratory, Richland, Washington 99352, United States.
Journal of the American Society for Mass Spectrometry
|November 19, 2025
Summary
Ion confinement in rotating electric fields depends on ion mobility and electric field strength. Optimal confinement is achieved by balancing ion velocity with field rotation speed, defined by a dimensionless parameter α.
Area of Science:
- Analytical Chemistry
- Physical Chemistry
Background:
- Ion mobility is a critical factor in mass spectrometry.
- Controlling ion behavior in electric fields is essential for ion optics.
Purpose of the Study:
- To investigate ion confinement based on mobility in rotating electric fields.
- To evaluate the performance of the All Pressure Ion Confinement (APIC) device.
Main Methods:
- Constructed a device with segmented ring electrodes and applied sinusoidal waveforms.
- Utilized a quadrupole time-of-flight mass spectrometer to monitor ion intensities.
- Tested ion mixtures across a broad mobility range at pressures of 3.8-8.0 Torr.
Main Results:
- Ion confinement is directly dependent on ion mobility and electric field strength.
- Higher pressures necessitate stronger electric fields for maximum ion intensity.
- Optimal ion confinement was observed for a dimensionless parameter α (0.1 < α < 1.5), balancing ion velocity and field rotation.
Conclusions:
- Ion mobility significantly influences confinement in rotating electric fields.
- The dimensionless parameter α is crucial for predicting and optimizing ion confinement.
- Findings guide the design of ion optics utilizing rotating electric fields.
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