PART I: DISPERSION VERSUS ABSORPTION (DISPA) LINE SHAPE ANALYSIS. PART II: ION TRAJECTORIES AND EXCITATION TECHNIQUES IN FOURIER TRANSFORM ION CYCLOTRON MASS SPECTROMETRY

Part I. For rapid molecular rotational motion ((omega)(,o)(tau)(,c) << 1), all three possible single quantum transitions for a spin 3/2 quadrupolar nucleus are characterized by the same Larmor frequency and width. For slow motion ((omega)(,o)(tau)(,c) (GREATERTHEQ) 1) the transitions are distinguished by a narrow and broad component lines with different resonant frequencies. This study provided the first experimental demonstration of the dynamic frequency shift by the method of dispersion versus absorption (DISPA) line shape analysis. The DISPA resolved frequency shift was further confirmed by a 180(DEGREES) - (tau) -10(DEGREES) inversion-recovery pulse sequence which separates the narrow and broad transitions according to their different recovery rates.;Part II. Fourier transform ion cyclotron mass spectrometry has so far been achieved using pulsed and frequency sweep excitation. In this section, a continuous excitation with no net electric field amplitude at a given m/q ration was generated through the concept of acceleration/deceleration. The relative merits of using pseudo-random noise as a spectral source were discussed. A Fourier synthesized selective excitation was introduced to produce any desired frequency-domain excitation waveform with uniform amplitude over m/q ratios to be excited and zero amplitude elsewhere. This excitation scheme was shown profitable for MS/MS and multiple-ion-monitoring applications.;Ion cyclotron trajectories were constructed from equation of motion of two moving ions in the presence of magnetic, electric and Coulomb effects. It was found that Coulomb repulsion results in line broadening, which decreases non-linearly with increasing ICR radius. Experimentally, it was found that there is an excitation period optimal for high resolution and accurate mass measurements.;A DISPA plot for a single Lorentzian spectral line gives a perfect circle, which serves as a reference curve for more complex line shapes. However, a spectrum consisting of a single Gaussian line gives a highly distorted DISPA plot. In this work, the distorted DISPA plot for a single Gaussian line was reduced back to a circle. This "reduced" DISPA plot for overlapping Gaussians was shown to give the same diagnostic features as the direct DISPA plot for overlapping Lorentzians.