| The application of a Fourier transform ion cyclotron resonance (FTICR) mass spectrometer to the observation of ion motion during excitation is detailed in this dissertation. This new capability, simultaneous excitation/detection (SED), is achieved with an externally adjustable capacitive matching network that is attached directly to the trapped-ion cell. This circuit permits a reduction in the RF signal that is coupled to the detection circuitry during excitation by 13-fold. The spectrometer is shown to generate real-time excitation profiles for the evaluation of axial and radial ion loss from the cell. Each profile can be acquired in 2 seconds compared to a 15 minute acquisition time by conventional methods. Experimental parameters such as trapping potential, neutral pressure, and delay time before excitation are evaluated in 1 hour by the SED method. The conventional method would have required more than 8 hours to collect and analyze the same data.;The experimental parameters affecting magnetron growth within the trapped-ion cell are observed. A method is demonstrated for consistently inducing coherent magnetron growth by direct excitation at the magnetron frequency. This technique yields a 63% improvement in the reproducibility of magnetron growth initiation. The ability to produce a stable magnetron radius for an ion cloud permits the quantitative evaluation of quadrupolar excitation (QE) for minimizing radial ion loss. A new approach is shown for the evaluation of QE in which the magnetron expansion of small mass ions is monitored directly. For example, benzene molecular ions were retained from a large orbital radius with an efficiency of 87%. The 13% ion loss was attributed to ions other than the molecular ion which were not axialized by the QE event. The optimized QE parameters were then applied for the first successful remeasurement of a small mass ion; a 94.7% remeasurement efficiency was achieved for more than 50 scans of benzene at 5 x 10-8 Torr. Broadband QE is then demonstrated to allow for the continuous remeasurement of a single population of small mass ions during a gas-phase reaction. With this technique the self-chemical ionization reaction of the same toluene ions with toluene neutrals was observed for several hundred seconds. |
