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A simulation study of the digital ion trap mass spectrometer

2002; Elsevier BV; Volume: 221; Issue: 2 Linguagem: Inglês

10.1016/s1387-3806(02)00921-1

1873-2798

Li Ding, Michael Sudakov, S. Kumashiro,

Analytical chemistry methods development

The theoretical foundation for the digital ion trap (DIT) is presented in outline where the study of ion motion in the DIT employed the a, q, β parameter framework of conventional ion trap study. A user program for SIMION has been developed to simulate the DIT operation in real environment allowing the higher-order fields to be represented. Three-dimensional random ion buffer gas collisions were modelled where Maxwellian velocity distribution of the buffer gas was considered. A mass-selective ejection scan method is described and simulated, where both the trapping quadrupole field and dipole excitation field are driven digitally and their frequencies are scanned proportionally. The performances of the stretched ion trap and a new field-modified ion trap are simulated and compared. Using a field-adjusting electrode near the end-cap aperture, the new ion trap is able to achieve higher mass resolution for both forward and reverse mass scans. The simulation studies also the relation between the ejection time and the parameters of digital dipole excitation, the influence of space charge, duty cycle modulation as an alternative ejection scan method, and ion introduction into the ion trap.