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by Yu-san Cheung. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1994. / Includes bibliographical references. / ABSTRACT --- p.ii / ACKNOWLEDGMENTS --- p.iv / EDITORIAL NOTE --- p.v / CONTENTS --- p.vi / LIST OF TABLES --- p.ix / LIST OF FIGURES --- p.xii / Chapter CHAPTER 1. --- INTRODUCTION / Chapter 1.1 --- Potential Energy Surfaces --- p.1 / Chapter 1.2 --- Ab initio Method --- p.1 / Chapter 1.2.1 --- Basis Sets --- p.2 / Chapter 1.2.2 --- Correlation Methods --- p.4 / Chapter 1.3 --- Locations and Characterizatioiis of Stationary Points --- p.5 / Chapter 1.4 --- Refinements of Energy and the Gaussian-2 Method --- p.7 / REFERENCES --- p.10 / Chapter CHAPTER 2. --- AN AB INITIO MOLECULAR ORBITAL STUDY OF THE GaH4 POTENTIAL ENERGY SURFACE / Chapter 2.1 --- Introduction --- p.12 / Chapter 2.2 --- Computational Details --- p.12 / Chapter 2.3 --- Results and Discussion --- p.13 / Chapter 2.3.1 --- Jahn-Teller Distortion from Td Symmetry --- p.18 / Chapter 2.3.2 --- Transition Structures Connecting Various Equilibrium Structures --- p.19 / Chapter 2.3.3 --- The Dissociation Products --- p.20 / Chapter 2.4 --- Conclusion --- p.21 / REFERENCES --- p.22 / Chapter CHAPTER 3. --- A GAUSSIAN-2 AB INITIO STUDY OF THE CH3S2 AND CH3S2+ POTENTIAL ENERGY SURFACES / Chapter 3.1 --- Introduction --- p.24 / Chapter 3.2 --- Computational Details --- p.25 / Chapter 3.3 --- Results and Discussion --- p.26 / Chapter 3.3.1 --- The Potential Energy Surface of CH3S2 Radicals --- p.26 / Chapter 3.3.2 --- The Potential Energy Surface of CH3S2+ Cations --- p.37 / Chapter 3.3.3 --- The Equilibrium Structures of CH3S2- Anions --- p.40 / Chapter 3.3.4 --- Interpretation of Experimental Results with Theoretical Predictions --- p.40 / Chapter 3.4 --- Conclusion --- p.42 / REFERENCES --- p.43 / Chapter CHAPTER 4. --- A GAUSSIAN-2 AB INITIO STUDY OF THE CH3O2 AND CH302+ POTENTIAL ENERGY SURFACES / Chapter 4.1 --- Introduction --- p.46 / Chapter 4.2 --- Computational Details --- p.47 / Chapter 4.3 --- Results and Discussions --- p.48 / Chapter 4.3.1 --- The Equilibrium Structures of CH3O2 Radicals --- p.48 / Chapter 4.3.2 --- The Transition Structures of CH3O2 Radicals --- p.59 / Chapter 4.3.3 --- The Equilibrium Structures of CH3O2+ Cations --- p.62 / Chapter 4.3.4 --- The Transition Structures of CH3O2+ Cations --- p.66 / Chapter 4.3.5 --- "The Equilibrium Structures of CH3O2"" Anions" --- p.68 / Chapter 4.3.6 --- Comparisons with Available Experimental Results --- p.69 / Chapter 4.4 --- Conclusion --- p.59 / REFERENCES --- p.72 / Chapter CHAPTER 5. --- MISCELLANEOUS / Chapter 5.1 --- "A Gaussian-2 ab initio Study of CH3SSCH2,CH3SF and Their Cations" --- p.74 / Chapter 5.2 --- A Gaussian-2 ab initio Study of SF5 and SF5+ --- p.80 / Chapter 5.3 --- "A Gaussian-2 ab initio Study of SFn+/SFn/SFn -(n = 1, 2, 3)" --- p.84 / REFERENCES --- p.91 / Chapter CHAPTER 6. --- CONCLUSION --- p.93 / REFERENCES --- p.94 / "APPENDIX A. PROCEDURES IN THE G2, G2(MP3) AND G2(MP2) METHODS" / Chapter A.l --- Location of Geometry --- p.95 / Chapter A.2 --- "Approximation of the QCISD(T)/6-311+G(3df,2p) Energy" --- p.95 / Chapter A.3 --- High-Level Correlation (HLC) Correction --- p.96 / Chapter A.4 --- Zero-Point Vibrational Energy (ZPVE) --- p.96 / APPENDIX B ENTHALPY CALCULATION --- p.97

This thesis involves the interpretation of gravity and other potential field anomalies caused by layers of varying thickness. The partial differential equations of potential field theory are reviewed for gravitational and magnetic force fields. A similar review is carried out for steady-state heat transport and diffusion processes. For the gravitational force fields, solutions of the partial differential equations are listed in integral form for the following cases: single body with given constant density, infinitely thin sheet with variable mass density, two homogeneous layers with a slowly undulating interface and two layers with a vertically-constant-density lower layer. The solutions give the gravity anomaly in terms of the parameters of the source body. Heat transport phenomena of a similar nature are also discussed. The general expression obtained for the two homogeneous layers with a slowly undulating interface is used as an integral equation and applied to the derivation of crustal thickness variation in Oregon on the basis of two different computational methods. The first method, called the digitized algebraic method, solves the quasi-linearized form of the general integral equation by an iterative technique for three reference va1ues of the mean depth of the crust-mantle interface, viz., 25 km, 30 km, and 35 km. The second approach, called the second derivative approximation method, gives a solution by the Fourier transform technique to the linearized form of the general integral equation for the same three reference values of the mean depth of the crust-mantle interface. The above results as to the depth of the crust-mantle interface are compared with recent results with seismic refraction and dispersion data obtained along a profile in eastern Oregon. The value of the reference depth d which best reconciles with the above results and the seismic results turns out to be 30.25 km for the depth data on the basis of the algebraic method and 28.90 km for the depth data obtained with the second derivative approximation method. / Graduation date: 1972

Previous studies showed that emotional pictures capture attention. Further, this effect was decreased by manipulating spatial attention. In contrast, studies produced mixed findings for effects of perceptual load on attention to emotional pictures. Emotional pictures can be phobic or nonphobic. Because phobia might be an evolutionary adaption, it is possible that effects of phobic pictures on attention differ from effects of nonphobic emotional pictures. The present thesis aimed at investigating attention in spider phobia. Attention to emotional pictures was operationalized as event-related potentials (ERPs) (P1, early posterior negativity [EPN,] and late positive potential [LPP]). Two research questions were formulated. First, do phobic pictures evoke larger ERPs than what can be expected from arousal and valence? Second, are effects of spatial attention and perceptual load on ERPs the same for phobic and nonphobic emotional pictures? To investigate this, phobic and nonphobic negative pictures were presented to spider phobic and nonphobic participants. To determine effects of spatial attention on ERPs, participants were instructed to divert attention to a single letter that was presented in the periphery. To determine effects of perceptual load on ERPs, participants were instructed to perform a letter discrimination task on one, two, or three letters that were presented in the periphery. Study 1 showed enhanced LPP amplitudes to phobic pictures independent of arousal and valence. Further, this effect was present in both phobic and nonphobic participants. Study 2 showed that there was no effect of perceptual load on LPP to phobic pictures. Study 3 showed that spatial attention reduced LPP amplitudes, and to a similar extent for both phobic and nonphobic pictures. Further, perceptual load did not reduce EPN or LPP amplitudes to either phobic or nonphobic pictures. To conclude, the results suggest that phobic pictures evoke larger ERP amplitudes than nonphobic pictures. Still, ERPs to phobic and nonphobic pictures are moderated similarly by spatial attention and perceptual load. / <p>At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 1: Manuscript. Paper 3: Manuscript.</p>

Electronic structure of a conventional superconductor in the vicinity of a single, iso- lated magnetic impurity has been probed experimentally with scanning tunneling spectroscopy by Yazdani et al.. Motivated by their experiment, we study the ef- fects of a single magnetic impurity on superconductivity by means of the mean-¯eld Bogoliubov-de Gennes theory. The Bogoliubov-de Gennes equations are solved di- rectly and numerically, utilizing parallel computation on a CFI-founded 128-CPU Beowulf-class PC cluster here at the University of Saskatchewan. As a preliminary study, we also examine the electronic structure around a magnetic vortex. The local magnetic field around a vortex breaks up Cooper pairs and suppresses superconduc- tivity locally. Quasiparticle excitations are created and bound in the vortex core area due to repeated Andreev scattering. A magnetic impurity tends to align the spins of the neighboring electrons and break up Cooper pairs, and has similar effects of lo- cally suppressing superconductivity. A striking difference, however, from the vortex problem is that around a magnetic impurity there is particle-hole asymmetry in the tunneling conductance. This is due to different probability amplitudes in the spin-up branch and the spin-down branch of quasiparticle excitations. Furthermore, for the spin potential strength larger than a certain critical value, the nature of quasiparticle excitations is changed dramatically. Within a model of classical spin, we propose an explanation of the measured tunneling conductance of the experiment. This work is significant in that it gives us insight into superconductivity and magnetism{two complementary manifestation of strong electron correlations.

Electronic structure of a conventional superconductor in the vicinity of a single, iso- lated magnetic impurity has been probed experimentally with scanning tunneling spectroscopy by Yazdani et al.. Motivated by their experiment, we study the ef- fects of a single magnetic impurity on superconductivity by means of the mean-¯eld Bogoliubov-de Gennes theory. The Bogoliubov-de Gennes equations are solved di- rectly and numerically, utilizing parallel computation on a CFI-founded 128-CPU Beowulf-class PC cluster here at the University of Saskatchewan. As a preliminary study, we also examine the electronic structure around a magnetic vortex. The local magnetic field around a vortex breaks up Cooper pairs and suppresses superconduc- tivity locally. Quasiparticle excitations are created and bound in the vortex core area due to repeated Andreev scattering. A magnetic impurity tends to align the spins of the neighboring electrons and break up Cooper pairs, and has similar effects of lo- cally suppressing superconductivity. A striking difference, however, from the vortex problem is that around a magnetic impurity there is particle-hole asymmetry in the tunneling conductance. This is due to different probability amplitudes in the spin-up branch and the spin-down branch of quasiparticle excitations. Furthermore, for the spin potential strength larger than a certain critical value, the nature of quasiparticle excitations is changed dramatically. Within a model of classical spin, we propose an explanation of the measured tunneling conductance of the experiment. This work is significant in that it gives us insight into superconductivity and magnetism{two complementary manifestation of strong electron correlations.

This thesis utilized the concept of an optically stimulated Contact Potential Difference (osCPD) sensor to monitor oil properties. The osCPD technique is a variant of the contact potential difference (CPD) method used to obtain surface properties of materials. The technique uses modulated light to stimulate electron charge carriers in silicon coated with a layer of oil. Demonstration of this oil monitoring design was done by placing different oil samples on the silicon surface and monitoring the corresponding electrical signal with the osCPD sensor. Experiments showed that the osCPD sensor produced an electrical signal that was related to the amount of time an oil sample was aged in an engine (or mileage). Further, a linear relationship was found between the relative conductivity of these oils and the osCPD signal. It is theorized that this osCPD signal is dependant on the charge transfer at the silicon and oil interface. Investigation of this interaction was carried out. Experiments showed that adding a silicon nitride passivation layer on the silicon surface eliminated the change in osCPD signal with oil properties. A model of this charge interaction was developed.

ABSTRACT Being a densely populated and heavily industrialized harbor, the emissions of air pollutants in the Kaohsiung area are very huge. There is substantial amount of VOCs (volatile organic compounds) present in the ambient air. Furthermore, relative high temperature and strong sunlight tend to transform these VOCs to oznone, causing high ozone episodes. This study aimed to determine the VOCs source profiles (or fingerprints) from 20 stationary sources, 10 from each of Kaohsiung City and Kaohsiung County. These include flue gas emission from incineration plants, sewage treatment plants, petroleum plants, and others. The samples was collected using a stainless-steel thermal desorption tube, then analyzed a Hewlett-Packard 58900-II gas chromatograph, fitted with a flame ionization detector and desk-top personel computer. The OFP (ozone formation potential) of VOCs from individual sources were evaluated based on MIR (maximum incremental reactivities). The results show that the speciations of VOCs depend on the raw material and air pollution control equipments used in the processes. The major VOCs in the petro-chemical industries are benzene, toluene, xylene, and 1,3,5-trimethylbenzene. The major VOCs in the PVC processes and surface-painting industries are 2-methylbutane, 2-methylpentane, and ethylbenzene. The major VOCs in the sewage treatment plants are ethylene, hexane, benzene, toluene, and m-xylene. The highest average reaction of the samples is 27.94 g-O3/g-VOCs from intermediary process, the next are from lubrication oil distillation tower, TPE process, ABS process, and maleic anhydride process, ranging from 3 ~ 5 g-O3/g-VOCs. Thus, the reactivity of aromatic-related process is highest, the next are aldehydes - and ketones -related processes. Keywords: Volatile Organic Compounds, Fingerprints, Ozone Formation Potential