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Analysis of ion cyclotron resonance

University of British Columbia

An analysis of the most commonly used type of Ion Cyclotron Resonance (ICR) spectrometer is given. Though the equations of motion of an isolated ion in the ICR geometry are extremely non-linear, it was found possible to decouple the longtitudinal oscillations due to the trapping potential from the cyclotron motion by exploiting the fact that the cyclotron frequency is very much greater than the trapping frequency. A previously unsuspected dependence of the cyclotron frequency and drift velocity of an ion on its spatial coordinates was discovered and experimentally investigated. The distribution of energies for ions at resonance with an applied r-f electric field is also discussed and improved techniques for the study of energy dependent cross-sections are proposed. Conventional ICR techniques were used to estimate collision frequencies of sodium and potassium ions in helium and argon gases. These experiments yield information about the d.c. drift mobility, in the zero field limit, of the alkali ions in inert gases and are discussed in terms of various models of the ion-atom interaction potential. A crossed beam arrangement was used to obtain preliminary estimates of low energy rate constants for both asymmetric and symmetric resonant charge transfer between alkali ion-atom pairs.

Text

2010-02-01

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http://hdl.handle.net/2429/19535

Physics

University of British Columbia

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