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Part I. Fast atom bombardment mass spectrometry: Discrimination effects and matrix chemistry. Part II. High-energy collisional activation of fullerenes and alkaline earth monohalides
Abstract
This dissertation describes fundamental studies encompassing two areas of mass spectrometry: fast-atom bombardment (FAB) ionization and collisional activation. Mixture analysis by FAB-MS is hindered by concentration-dependent discrimination arising from differences in surface activity and micelle formation (Chapter 1). The use of a nonpolar matrix, n-dodecanol, reduced the discrimination effects in the analysis of mixtures of saturated fatty acids. The chemical and physical changes that occur in glycerol as a result of fast-atom bombardment were determined from accurate mass measurements and tandem mass spectrometry (Chapter 2). Proton transfer to ambient glycerol molecules from the glycerol radical cation and its fragments is proposed to account for bombardment-induced ion formation from neutral glycerol. The products of high-energy (keV) collisions of fullerene radical cations with noble gases, as well as D$\sb2,$ N$\sb2,$ NO, and O$\sb2$ were investigated by using a three-sector and a four-sector tandem mass spectrometer (Chapter 3). Atomic target gases and D$\sb2$ were captured directly, and the various endohedral ("in the cage") complexes were observed as product ions. Analysis of the kinetic energies of the product ions produced from He and D$\sb2$ collisions leads to the conclusion that the observed product ions from He and D$\sb2$ collisions are fragments of the endohedral complexes. Abundant doubly charged product ions were detected in collisions with N$\sb2,$ NO, and O$\sb2$ target gases, and the second ionization energies of the neutral fullerenes were determined from translational energy loss measurements. Alkaline earth monohalide cations were desorbed from the dihalide salt and investigated by using tandem mass spectrometry (Chapter 4). The singly charged ions undergo charge stripping in collisions with air or O$\sb2$ to produce doubly charged ions which, if bound, will be the first example of bound doubly charged ions. The second ionization energies of the neutral alkaline earth monohalides and four oxygen-containing species were determined. The trends in the product ion abundances and in the second ionization energies were discussed in terms of the properties of the alkaline earth metals and the halogens as well as simple bonding schemes.
Subject Area
Analytical chemistry|Chemistry
Recommended Citation
Caldwell, Kenneth A, "Part I. Fast atom bombardment mass spectrometry: Discrimination effects and matrix chemistry. Part II. High-energy collisional activation of fullerenes and alkaline earth monohalides" (1992). ETD collection for University of Nebraska-Lincoln. AAI9233394.
https://digitalcommons.unl.edu/dissertations/AAI9233394