Thesis (M.S.)--The Chinese University of Hong Kong. / Bibliography: leaves 68-71. / Chapter CHAPTER 1 --- INTRODUCTION --- p.1 / Chapter CHAPTER 2 --- PRINCIPLE OF NORMAL COORDINATE ANALYSIS --- p.5 / Chapter CHAPTER 3 --- THE UREY-BRADLEY FORCE FIELDS OF HEXAHALIDE IONS OF NIOBIUM AND TANTALUM --- p.20 / Chapter CHAPTER 4 --- THE UREY-BRADLEY FORCE FIELDS OF PERHALYL FLUORIDE --- p.34 / Chapter CHAPTER 5 --- THE UREY-BRADLEY FORCE FIELDS OF ISOTOPIC CHLORYL FLUORIDES --- p.47 / Chapter CHAPTER 6 --- CONCLUSION --- p.66 / BIBLIOGRAPHY --- p.68 / APPENDIX --- p.72

Title also in Chinese. / Thesis -- Chinese University of Hong Kong, 1977. / Bibliography: leaves 73-74.

Yim Kan-Hing. / Thesis submitted in: July 2005. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2006. / Includes bibliographical references (leaves 58-59). / Abstracts in English and Chinese. / TITLE PAGE --- p.i / THESIS COMMITTEE --- p.ii / ABSTRACT (ENGLISH) --- p.iii / ABSTRACT (CHINESE) --- p.iv / ACKNOWLEDGMENTS --- p.v / TABLES OF CONTENTS --- p.vi / LIST OF FIGURES --- p.viii / LIST OF TABLE --- p.xii / Chapter Chapter 1 --- Introduction --- p.1 / Chapter Chapter 2 --- Instrumentation and Experiment --- p.8 / Chapter Chapter 2A --- High resolution Ti:sapphire laser spectrometer --- p.8 / Chapter Chapter 2B --- Diode laser spectrometer --- p.12 / Chapter Chapter 2C --- Experimental set up and procedure for CEAS --- p.18 / Chapter Chapter 3 --- Results and Discussion --- p.33 / Chapter Chapter 3A --- Reflectivity of cavity mirrors --- p.33 / Chapter Chapter 3B --- Power-modulated CEAS --- p.40 / Chapter Chapter 3C --- Frequency-modulated CEAS --- p.47 / Chapter Chapter 3D --- Concentration-modulated CEAS --- p.48 / Chapter Chapter 4 --- Concluding Remarks --- p.56 / REFERENCES --- p.58

Thesis (M.S. in Physics)--Naval Postgraduate School, September 1990. / Thesis Advisor(s): Cleary, David D. Second Reader: Gnanalingam, Suntharalingam. "September 1990." Description based on title screen viewed on December 16, 2009. DTIC Descriptor(s): Airglow, ultraviolet spectra, emission, ionosphere, layers, intensity, theses, emission spectra, oxygen, profiles, flight, patterns, calibration, earth(planet), rockets, sounding rockets, temperate regions, line spectra, rocket research, test and evaluation, frequency. DTIC Identifier(s): Fastie spectrograph, dayglow. Author(s) subject terms: Ebert-Fastie Spectrograph, ultraviolet spectra, dayglow; OII 2770 Å multiplet; OI 2972 Å line emission. Includes bibliographical references (p. 108-109 ). Also available in print.

A Bonner Sphere neutron spectrometer for low background environment was developed. The spectrometer consists of a 3He neutron detector, eight high density polyethylene spheres with size ranging from 5-inch to 12-inch and two Lead shells with thickness 1cm and 2 cm, which is used to increase the detect efficiency at high energy range. The dead time of the spectrometer is about 3.7 microseconds, which is mainly contributed by the extended TTL signal from the DAQ. The background of 3He detector is measured in CJPL which is the deepest underground laboratory in the world. The detector background is 15.50 × 10-4 ± 8.1 × 10-5 counts per second. The responses of Bonner Spheres were obtained by Geant4 Monte Carlo simulation. The responses were verified by a 241AmBe neutron source in HKU. A genetic algorithm unfolding program(GA) was developed and tested by unfolding the 241AmBe neutron source. The background neutron in HKU Observatory was measured by the spectrometer and unfolded by GA s. The unfolded neutron flux is (56.84 ± 6.01) × 10-4 s-1 cm-1 by NSUGA version 3 and (56.43 ± 2.53) × 10-4 s-1 cm-1from NSUGA_FORTRAN. Another unfolding program "Equalizer" with different algorithm, by scaling a initial guess spectrum, was also used to unfold the background spectrum in HKU Observatory. The unfolded neutron flux from "Equalizer" is (51.69 ± 2.79) × 10-4 s-1 cm-1. The neutron flux from three unfolding programs agree with each other. The measurement was repeated in Daya Bay EH1 and the results were used to unfold the background neutron spectrum. The unfolded spectrum flux was (34.50 ± 3.13) × 10-5 s-1cm-1from NSUGA version 3, (35.13 ± 1.45) × 10-5 s-1cm-1 from NSUGA_FORTRAN. The unfolded neutron fluxes from GA s agree with each other. However the shape of spectra shows a chaotic pattern in low energy region. The unfolded neutron flux from "Equalizer" is (30.85 ± 1.95) × 10-5 s-1c m-1. The unfolding programs show a dominant thermal neutron peak, a tiny (α, n) peak and a small cosmic-ray neutron peak. The Bonner Spheres Spectrometer has flaws due to the geometry and the nature of unfolding process. Some ideas are suggested to minimize the effect from the error sources. / published_or_final_version / Physics / Master / Master of Philosophy

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Spectroscopic observations of fourteen broad absorption line (BAL) QSOs are presented and analyzed. Other observations are summarized. The following major conclusions are reached. Broad absorption lines (BALs) are probably present in 3 to 10 percent of the spectra of moderate to high redshift QSOs. The BALs exhibit a variety of velocity structures, from seemingly smooth, continuous absorption to complexes of individual absorption lines. Outflow velocities up to 40,000 km s⁻¹ are observed. The level of ionization is high. The minimum total absorption column densities are 10²⁰ to 10²² cm⁻². The emission line properties of BAL QSOs appear to be different from those of non-BAL QSOs. For example, N V emission is generally stronger in BAL QSOs and the emission near C III] λ1909 is generally broader in BAL QSOs. The distribution of multiplicities for isolated absorption troughs suggests that the large-scale spatial distribution of BAL clouds is non-random, possibly described by a disk geometry. The BAL clouds are incapable of accounting for all of the observed broad emission lines, particularly C III] λ1909 and Mg II λ2798. Therefore, if the BAL clouds give rise to observable emission, the generally adopted (optically thick, single component) model for the emission line region must be incorrect. Also, photoionization models, which utilize solar abundances and take the ionizing continuum to be a simple power law, are incapable of explaining the level of ionization in the BAL clouds. By considering the observed percentage of QSOs with BALs and resonance line scattering models, it is found that the absorption covering factor in BAL QSOs is between 3 and 20 percent. This suggests that possibly all, but not less than 15 percent, of the QSOs have BAL clouds associated with them. The amount of observable emission and polarization expected to be produced by the BAL clouds from resonance line scattering and collisional excitation is considered in detail. It seems likely that the BAL clouds contribute to the observed high ionization emission. A model worth exploring is one in which an inner, optically thick component gives rise to the low ionization emission, whereas an outer BAL cloud region gives rise to much of the high ionization emission.

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