Space charge effects in linear quadrupole ion traps
department or school: Science, Faculty of
department or school: Chemistry, Department of
data provider: DSpace
degree campus: UBCV
creator: Gao, Cong
issued: 2015-02-11T22:30:31Z
issued: 2015
related degree: Doctor of Philosophy - PhD
degree grantor: University of British Columbia
description: Space charge effects in a linear quadrupole ion trap operated with mass selective axial ejection have been investigated. If too many ions are confined in an ion trap, the Coulomb repulsion between ions, or from "space charge", causes ions to shift towards higher apparent mass-to-charge ratio (m/z) in a mass spectrum. This phenomenon, called "mass shifts", can be described by a model with the assumption that the trapped ions have a Boltzmann or thermal distribution of positions in an effective potential. The two parameters in this model, the ion temperature and the effective potential, are determined in this thesis, allowing improved modelling of space charge effects with well determined parameters. Space charge effects were also studied experimentally, including the simplest case (self-space charge) and the most difficult case (space charge from a heavy ion species of high abundance). A new technique to lower mass shifts, dual-frequency excitation, was introduced and optimized. As a result, the instrument performance of linear quadrupole ion trap mass analyzers, including the intensity, limits of detection and the trap capacity, can be improved.
aggregated CHO: https://circle.library.ubc.ca/rest/handle/2429/52153
note: Space Charge Effects in Linear Quadrupole Ion Traps by Cong Gao B.Sc., Peking University, 2010 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY in The Faculty of Graduate and Postdoctoral Studies (Chemistry) THE UNIVERSITY OF BRITISH COLUMBIA (Vancouver) February 2015 © Cong Gao, 2015 ii Abstract Space charge effects in a linear quadrupole ion trap operated with mass selective axial ejection have been investigated. If too many ions are confined in an ion trap, the Coulomb repulsion between ions, or from "space charge", causes ions to shift towards higher apparent mass-to-charge ratio ( ) in a mass spectrum. This phenomenon, called "mass shifts", can be described by a model with the assumption that the trapped ions have a Boltzmann or thermal distribution of positions in an effective potential. The two parameters in this model, the ion temperature and the effective potential, are determined in this thesis, allowing improved modelling of space charge effects with well determined parameters. Space charge effects were also studied experimentally, including the simplest case (self-space charge) and the most difficult case (space charge from a heavy ion species of high abundance). A new technique to lower mass shifts, dual-frequency excitation, was introduced and optimized. As a result, the instrument performance of linear quadrupole ion trap mass analyzers, including the intensity, limits of detection and the trap capacity, can be improved. iii Preface A version of Chapter 2 has been published as a part of: Qiao, H.; Gao, C.; Mao, D. M.; Konenkov, N.; Douglas, D. J., Space-charge effects with mass-selective axial ejection from a linear quadrupole ion trap. Rapid Communications In Mass Spectrometry 2011, 25 (23), 3509-3520. The project was initiated and designed by Dr. Douglas. Dr. Qiao contributed to the data acquisition, the data analysis and the preparation of the manuscript. Mao and Konenkov conducted ion trajectory …
has type: Thesis/Dissertation
date issued: 2015-05
is shown at: 10.14288/1.0167667
language: eng
degree discipline: Chemistry
provider: Vancouver : University of British Columbia Library
publisher: University of British Columbia
rights: Attribution-NonCommercial-NoDerivs 2.5 Canada
rights URI: http://creativecommons.org/licenses/by-nc-nd/2.5/ca/
scholar level: Graduate
type: Text
identifier URI: http://hdl.handle.net/2429/52153