The design and implementation of a two-section Fourier transform ion cyclotron resonance spectrometer for ion-molecule reaction studies /
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| Other Authors: | , , |
| Format: | Thesis Book |
| Language: | English |
| Published: |
1989.
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| Subjects: | |
| Online Access: | ProQuest, Abstract Link to OAKTrust copy |
| Abstract: | Ion reactions can be studied with great versatility by using Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR). This versatility arises from two advantages of the technique; (i) the mass of ions can be routinely and rapidly measured with high resolution (m/Δm > 50,000) without significant loss of sensitivity, and (ii) ions can be stored in the spectrometer cell for periods ranging from less than 100 μs (instrumentally limited) to several seconds. For these reasons, FT-ICR has been selected for numerous probes of ions reactions with photons or neutrals (e.g. collisional activation). Routine high mass resolution allows nominal isobars to be resolved removing the ambiguities associated with many systems such as iron carbonyls (nom. m/z 56 amu for both Fe and 2(CO)). Ion storage on the FT-ICR timescale allows one to follow ion reaction kinetics accounting for most chemical studies performed by FT-ICR. A two-section cell FT-ICR system adds an additional degree of control to both analytical and chemical studies. The differentially pumped vacuum system is found to allow greater control of ion-molecule reaction parameters than in conventional single cell systems. In the two-section cell, competing relations of ions can be separated by electrically moving ions from one distinct reaction region to another. Experiments reported here were performed to exploit this ability. Material choice in cell/lens construction is crucial for systems operating in strong magnetic fields. Magnetic inhomogeneities generated by stray fields present near paramagnetic lenses dramatically alter the trajectories of low momentum ions that pass nearby. Low energy ion injection into an FT-ICR cell is studied in Chapter IV using empirical and theoretical data for a two-section cell constructed of both paramagnetic and diamagnetic materials. A method for isolation due to selective partitioning in a two-section cell FT-ICR is described in Chapter V. The limitation on ion cyclotron radius imposed by the conductance limit aperture is utilized to isolate ions. This method allows ions to be isolated according to (i) mass, (ii) translational energy in the cyclotron orbit, and (iii) spatial location... |
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| Item Description: | Typescript (photocopy). Vita. "Major subject: Chemistry." |
| Physical Description: | xiii, 149 leaves : illustrations ; 29 cm |
| Bibliography: | Includes bibliographical references. |