A new Linear RFQ Ion Trap/Axial Time-of-Flight mass spectrometer was developed and tested. A segmented quadrupole rod system was used to create a static axially confining field that could trap and cool an ion cloud from a DC ion source. In addition, an adjustable extraction field was applied, after sufficient ion collection, by pulsing the trapping rod segments to send the cooled ion cloud into a collinear Time-of-Flight spectrometer. Two chevron stacked multichannel plates, with a measured charge amplification of 3.75 x 107, were used as a detector at the end of the flight tube. / The purpose of this work was to investigate ion dynamics in the linear trap (LTRAP) so as to determine the suitability of this system as a source for TOFMS. The trap was therefore designed to be relatively weak so that the ion collection volume would be large enough to obtain a detailed picture of the cloud. The system was tested using a Cs+ (m/ z =133) ion source. Optimal parameters were found to be an applied well depth of -5V to -15V with a q value between 0.3 and 0.6 in a buffer gas environment of N2 at pressures of 10 -4 Torr or greater. Under these conditions and a cooling/collection time of 50ms the trap was observed to contain about 2500 ions. This translated to a detection efficiency of about 26.7% of the ions entering LTRAP. / Computer simulations based on a thermodynamic model were created to analyze the experimental data. The ion ensemble was found to reach an equilibrium temperature of 0.0353 +/- 0.0025eV in less than 10ms. Another computer program was used to reconstruct the phase space density of the LTRAP collection from the detector signals. The results of this reconstruction agreed with the results obtained from the model fitting procedure thereby confirming the thermodynamic model. / The phase space density distribution in LTRAP showed that with a time-focusing reflectron even this weak trap would have a m/Delta m = 250. This has led to guidelines for the construction of a high-resolution hybrid mass spectrometer using a linear ion trap. Based on these current results, a mass resolution of almost 10,000 is predicted as an upper limit of this type of mass spectrometer.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.36924 |
| Date | January 2000 |
| Creators | Fong, C. W. Van (Chun Wan Van), 1973- |
| Contributors | Moore, R. B. (advisor) |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Doctor of Philosophy (Department of Physics.) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 001809545, proquestno: NQ70017, Theses scanned by UMI/ProQuest. |
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