Thesis (M. S.)--Chemistry and Biochemistry, Georgia Institute of Technology, 2009. / Committee Chair: Thomas Orlando; Committee Member: Joseph Perry; Committee Member: Nicholas Hud; Committee Member: Phillip First; Committee Member: Rigoberto Hernandez.

No description available.

Thesis (M. Phil.)--University of Hong Kong, 2002. / Includes bibliographical references (leaves 57-58).

No description available.

Understanding the radiation chemistry of water is important in many disciplines including the nuclear industry, astrochemistry, and medicine. In recent years, low-energy electrons have been paid much greater attention, due to their abundance and reactivity in irradiated materials. Electrons with energies < 20 eV may interact via the dissociative electron attachment (DEA) mechanism, which has been found to cause single-strand breaks in DNA.DEA in water involves the capture of a low energy electron by a neutral water molecule into an outer orbital and is generally accompanied by excitation of the H2O molecule, causing it to dissociate. The aim of this work is to study the OH radical produced in DEA to H2O using laser-induced fluorescence (LIF).A high-vacuum chamber equipped with low energy electron gun, molecular beam and laser system was built for gas-phase studies of DEA in water. LIF spectra were recorded from OH formed by dissociation of gas-phase H2O, for determination of the rotational and vibrational state distributions. In addition to the gas-phase studies, low-energy (100 eV) electron-stimulated reactions in layered H2O/CO/H2O ices were investigated using a combination of temperature-programmed desorption (TPD) and infrared reflection-absorption spectroscopy (IRAS).For CO trapped within approximately 50 mono-layers of the vacuum interface both reduction and oxidation products were observed including HCO, H2CO, H3CO and CH3OH, and CO2. Concentration profiles of CO versus film thickness showed two zones in the film: a near-surface zone of preferential oxidation, and a zone of preferential reduction deeper in the film. A Monte Carlo model was developed based on diffusion of H atoms through the ice lattice, which supported the experimental results.

published_or_final_version / Physics / Master / Master of Philosophy

by Chu Hon Yue. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1990. / Bibliography: leaves 91-93. / ACKNOWLEDGEMENT --- p.i / ABSTRACT --- p.ii / Chapter I. --- INTRODUCTION --- p.1 / Chapter II. --- LOW ENERGY ELECTRON DIFFRACTION --- p.4 / Chapter 2.1. --- LEED EXPERIMENT --- p.4 / Chapter 2.2. --- LEED CRYSTALLOGRAPHY：I(E) CURVE --- p.7 / Chapter 2.3. --- AN OUTLINE OF THE PHYSICS OF LEED --- p.8 / Chapter 2.3.1. --- LEED Process In One-Dimensional Surface --- p.8 / Chapter 2.3.2. --- LEED Process In Three-Dimensional Surface --- p.11 / Chapter 2.3.3. --- Surface With An Overlayer --- p.12 / Chapter 2.3.4. --- The Muffin-Tin Model And The Inner Potential --- p.13 / Chapter 2.3.5. --- The Phase Shift --- p.17 / Chapter 2.3.6. --- Thermal Effects --- p.19 / Chapter III. --- DYNAMICAL LEED CALCULATION： THE RENORMALIZED FORWARD SCATTERING PERTURBATION METHOD --- p.22 / Chapter IV. --- THE ZANAZZI-JONA RELIABILITY FACTOR --- p.30 / Chapter V. --- CALCULATIONS AND RESULTS --- p.33 / Chapter 5.1. --- EXPERIMENTAL I(E) CURVES --- p.33 / Chapter 5.2. --- CALCULATED I(E) CURVES --- p.36 / Chapter 5.2.1. --- Top Site --- p.4o / Chapter 5.2.2. --- Bridge Site --- p.41 / Chapter 5.2.3. --- Hollow Site --- p.42 / Chapter VI. --- DISCUSSIONS AND CONCLUSIONS --- p.44 / APPENDIX I --- p.51 / TABLES --- p.52 / I(E) CURVES AND CONTOUR MAPS --- p.61 / APPENDIX II --- p.79 / MAIN PROGRAMME FOR Rh(100)-c(2x2) -S --- p.80 / INPUT PARAMETERS FOR TOP SITE --- p.85 / INPUT PARAMETERS FOR BRIDGE SITE --- p.87 / INPUT PARAMETERS FOR HOLLOW SITE --- p.89 / REFERENCES --- p.91

Includes bibliographical references (p. 118-122).

Zinc oxide surfaces have been of considerable interest because of their favorable properties, such as high electron mobility, good transparency, large electronic breakdown field and wide bandgap. Knowing the surface structure of ZnO is the key to better understand the above phenomena and to further develop its applications. In this thesis, the Patterson Function was evaluated by inversion of LEED I-V spectra at multiple incident angles to determine the surface structure of the ZnO(0001) polar surface. The sample was prepared by degassing and then 15 cycles of argon sputtering and annealing. The experimental LEED I-V spectra from multiple incident angles were taken from the sample. After processing the data by a macro program in OPTIMAS and a Matlab program, a clean Patterson Function map showing the inter-atomic pair distances was obtained. It was then compared with the simulated Patterson Function map of the proposed 1×1 bare surface model. As a result, the spots positions in the simulated Patterson Function map matched well with that of the experimental Patterson Function map. On the other hand, the LEED I-V curve fitting work was done by the surface science group of City University of Hong Kong. Six models were proposed by them and normal incidence theoretical LEED I-V spectra were calculated to fit with the experimental LEED I-V curves provided by us. Among the six models 2×2 Zn point defect model was fitted to be the best model with the R-factor 0.244. We also compared the multiple scattering simulated Patterson Function map of 2×2 Zn point defect model with the experimental one to verify the validity of the model. As a result, the model fit the experimental data. So we conclude that in general 1×1 model support the order part, and 2×2 top layer Zn defect model best fits the random missing part. / published_or_final_version / Physics / Master / Master of Philosophy

published_or_final_version / Physics / Master / Master of Philosophy