A study of the performance of an ion shutter for drift tubes in atmospheric pressure ion mobility spectrometry: Computer models and experimental findings
- Department of Chemistry and Biochemistry, New Mexico State University, Las Cruces, New Mexico 88003 (United States)
- Department of Environmental Sciences, Laboratory of Applied Environmental Chemistry, University of Kuopio, Mikkeli FIN-50100 (Finland)
- Department of Chemistry, Queens University, Kingston, Ontario K7L 3N6 (Canada)
Ion mobility spectra are initiated when ions, derived from a sample, are pulsed or injected through ion shutters into a drift region. The effect on signal intensity from electric fields arising from the shutter grids (E{sub s}) and a superimposed electric field of the drift tube (E{sub d}) was determined experimentally and simulated computationally for ion motion at ambient pressure. The combination of these two fields influenced shutter performance in three ways: (1) intensity of an ion peak was suppressed by increased current in the baseline due to continuous leakage of ions into the drift region from insufficient E{sub s} to block ion motion when needed, at a given value of E{sub d}; (2) the ion shutter provided maximum peak intensity with some optimal ratio of E{sub s}/E{sub d} when ions were fully blocked except using the injection time; (c) the signal intensity was reduced when the blocking voltage of the ion shutter exceeded this optimal E{sub s}/E{sub d} ratio from ion depletion at the shutter grids. The optimal ratio from the computer models was equal to 1.50, whereas a value of 2.50 was obtained from the experimental findings. This difference was attributed to nonideal geometry with the grids of the shutter and the conducting elements in the drift tube establishing both E{sub s} and E{sub d}. As both the experimental and modeling results demonstrated, a mobility dependence of ion yield from the ionization source was found to cause a mobility dependent ion signal at the collector electrode.
- OSTI ID:
- 22051054
- Journal Information:
- Review of Scientific Instruments, Vol. 80, Issue 10; Other Information: (c) 2009 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0034-6748
- Country of Publication:
- United States
- Language:
- English
Similar Records
Plasma sheet motions inferred from medium-energy ion measurements
Simulation of Ion Motion in FAIMS through Combined Use of SIMION and Modified SDS