Thesis (Ph. D.)--Brigham Young University. Dept. of Chemistry and Biochemistry, 2006. / Includes bibliographical references.

The photoelectron spectra of a series of ketone compounds have been investigated in the gas phase. Core ionization energies were measured to probe the effects of molecular size and connectivity number on core ionization energies. It was found that core ionization energies roughly decrease with increasing connectivity number as expected. However, subdividing into several categories based on the molecular type gives improved correlations. These results show both the effect of molecular size and that of bringing the polarizable group closer to the core ionized center. In some cases, compounds with the same connectivity number have different core ionization energies and, in others, compounds with different connectivity number have the same core ionization energies. These discrepancies indicate that the simple method for calculating connectivity numbers must be modified to reflect different molecular types. Other discrepancies indicate that this method does not correctly predict the effects of remote hydrogens or the effects of aromatic substituents, where conjugation may influence the relaxation energy. / Graduation date: 1995

The above threshold ionization (ATI) spectra provide a diversity of information about a laser-atom ionization process such as laser intensity, pulse duration, carrier envelope phase, and atomic energy level spacing. However, the spatial distribution of intensities inherent in all laser beams reduces the resolution of this information. This research focuses on recovering the intensity-resolved ATI spectra from experimental data using a deconvolution algorithm. Electron ionization yields of xenon were measured for a set of laser pulse intensities using a time of flight (TOF) setup. Horizontally polarized, unchirped, 50fs pulses were used in the ionization process. All laser parameters other than the radiation intensity were held constant over the set of intensity measurements. A deconvolution algorithm was developed based on the experimental parameters. Then the deconvolution algorithm was applied to the experimental data to obtain the intensity-resolved total yield probability and ATI spectra. Finally, an error analysis was performed to determine the stability and accuracy of the algorithm as well as the quality of the data. It was found that the algorithm produced greater contrast for peaks in the ATI spectra where atom specific resonant behavior is observed. Additionally, the total yield probability showed that double ionization may be observed in the ionization yield. The error analysis revealed that the algorithm was stable under the experimental conditions for a range of intensities.

The asymptotic behavior of the wave functions of three charged particles has been investigated. There are two different types of three-body scattering wave functions. The first type of scattering wave function evolves from the incident three-body wave of three charged particles in the continuum. The second type of scattering wave function evolves from the initial two-body incident wave. In this work the asymptotic three-body incident wave has been derived in the asymptotic regions where two particles are close to each other and far away from the third particle. This wave function satisfies the Schrodinger equation up to terms O(1/3pa), where pa is the distance between the center of mass of two particles and the third particle. The derived asymptotic three-body incident wave transforms smoothly into Redmond’s asymptotic incident wave in the asymptotic region where all three particles are well separated. For the scattering wave function of the second type the asymptotic threebody scattered wave has been derived in all the asymptotic regions. In the asymptotic region where all three particles well separated, the derived asymptotic scattered wave coincides with the Peterkop asymptotic wave. In the asymptotic regions where two particles are close to each other and far away from the third one, this is a new expression which is free of the logarithmically diverging phase factors that appeared in the Peterkop approach. The derived asymptotic scattered wave resolves a long-standing phase-amplitude ambiguity. Based on these results the expressions for the exact prior and post breakup amplitudes have been obtained. The post breakup amplitude for charged particles has not been known and has been derived for the first time directly from the prior form. It turns out that the post form of the breakup amplitude is given by a surface integral in the six dimensional hyperspace, rather than a volume integral, with the transition operator expressed in terms of the interaction potentials. We also show how to derive a generalized distorted-wave-Born approximation amplitude (DWBA) from the exact prior form of the breakup amplitude. It is impossible to derive the DWBA amplitude from the post form. The three-body Coulomb incident wave is used to calculate the reaction rates of 7Be(ep, e)8B and 7Be(pp, p)8B nonradiative triple collisions in stellar environments.

Cross sections for K-shell ionization by heavy ions have been determined from the measurements of target K x-ray yields. The measurements were performed with Ar, Kr, and Xe ions at energies from 2.5 to 25 MeV/amu and self-supported metallic foil targets of Al, Ti, Cu, Zr, Ag, Sm, and Ta. The x-ray yields were measured with a Si(Li) detector, while the projectile ions were counted in coincidence with the x-rays using a plastic scintillation detector. In addition, the amount of secondary K-shell ionization and the degree of simultaneous L-shell ionization in primary K-shell ionizing collisions were assessed by performing high-resolution x-ray measurements on targets of Al, Ti, V, Co, and Cu with a curved crystal spectrometer. The results of the high resolution measurements revealed that the apparent average Lshell spectator vacancy fraction at the time of Kα x-ray emission, L p , may be represented by a universal function of the Geometrical Model’s parameter X for Z2 = 17 - 32. Multiple-vacancy Kα fluorescence yields and corrections for K-shell ionization by secondary processes were determined with the aid of the high resolution spectra for the targets Al, Ti, and Cu. Fluorescence yields for the other targets were determined using an extrapolation procedure. The resulting K-vacancy production cross sections for 2.5 to 6 MeV/amu projectiles were compared with a limited amount of available experimental data and shown to be in relatively good agreement. The ECPSSR predictions for all the targets except Al agreed reasonably well with experimental cross sections for Ar projectiles. The experimental cross sections for Kvacancy production in Al, Ti, Cu, Zr, and Ag were greatly deviated from the ECPSSR predictions. The cross sections for Kr on Sm and Ta were in good agreement with theory. The scaling properties of the Kα x-ray production cross sections were examined and a semiempirical “universal” curve was deduced that reproduces the measured cross sections to within ±30% on average. The relationship between the Kα x-ray production cross sections and the geometrical model’s universal variable also was examined.

Thesis (Ph. D.)--University of Texas at Austin, 2001. / Vita. Includes bibliographical references. Available also in a digital version from Dissertation Abstracts.

Thesis (Ph. D.)--Chemistry and Biochemistry, Georgia Institute of Technology, 2010. / Committee Chair: Fernandez, Facundo M.; Committee Member: Bottonley, Lawrence A.; Committee Member: Kelly, Wendy L.; Committee Member: Merrill, Alfred; Committee Member: Orlando, Thomas; Committee Member: Sullards, Cameron. Part of the SMARTech Electronic Thesis and Dissertation Collection.

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