by Wang Yu = 一維納米結構硫化鎘的生長和表面 / 王瑜. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2005. / Includes bibliographical references. / Text in English; abstracts in English and Chinese. / by Wang Yu = Yi wei na mi jie gou liu hua ge de sheng chang he biao mian / Wang Yu. / Acknowledgements --- p.i / Abstract --- p.ii / 摘要 --- p.iii / Table of contents --- p.iv / List of figures --- p.vi / List of tables --- p.ix / Chapter Chapter 1 --- Introduction / Chapter 1.1 --- Background --- p.1-1 / Chapter 1.1.1 --- One-dimensional (1 -D) nanostructures --- p.1-1 / Chapter 1.1.2 --- "Characteristics, properties, and applications of 1 -D nanostructures" --- p.1-1 / Chapter 1.1.3 --- Synthesis and growth mechanisms --- p.1-3 / Chapter 1.1.3.1 --- Vapor-Liquid-Solid (VLS) mechanism --- p.1-4 / Chapter 1.1.3.2 --- Vapor-Solid (VS) mechanism --- p.1-5 / Chapter 1.2 --- II-VI semiconductor nanomaterials --- p.1-5 / Chapter 1.2.1 --- Cadmium sulfide (CdS) --- p.1-6 / Chapter 1.2.1.1 --- Characteristics and potential applications --- p.1-6 / Chapter 1.2.1.2 --- Works performed by others --- p.1-7 / Chapter 1.3 --- Objectives and approaches in this work --- p.1-8 / Chapter 1.4 --- Thesis layout --- p.1-9 / References --- p.1-10 / Figures --- p.1-13 / Tables --- p.1-14 / Chapter Chapter2 --- Methodology and instrumentation / Chapter 2.1 --- Experimental setup --- p.2-1 / Chapter 2.1.1 --- Substrates --- p.2-1 / Chapter 2.1.2 --- Experimental settings --- p.2-2 / Chapter 2.2 --- Growth parameters --- p.2-2 / Chapter 2.3 --- Characterization methods --- p.2-3 / Chapter 2.3.1 --- "Phase, morphology and microstructure analysis" --- p.2-3 / Chapter 2.3.1.1 --- X-ray diffractometry (XRD) --- p.2-3 / Chapter 2.3.1.2 --- Scanning electron microscopy (SEM) --- p.2-4 / Chapter 2.3.1.3 --- Transmission electron microscopy (TEM) --- p.2-4 / Chapter 2.3.1.4 --- High-resolution transmission electron microscopy (HRTEM) / Chapter 2.3.2 --- Cathodoluminescence (CL) --- p.2-5 / Chapter 2.3.2.1 --- Principles of CL --- p.2-5 / Chapter 2.3.2.2 --- Advantages of CL --- p.2-6 / Chapter 2.3.2.3 --- CL settings --- p.2-6 / References --- p.2-7 / Figures --- p.2-8 / Chapter Chapter3 --- Results and discussions part I - Growth of CdS nanobelts / Chapter 3.1 --- Characterization in general --- p.3-1 / Chapter 3.2 --- Morphology and microstructure --- p.3-1 / Chapter 3.2.1 --- Nanobelt with Au droplet at the tip --- p.3-2 / Chapter 3.2.2 --- Nanobelt without Au droplet at the tip --- p.3-2 / Chapter 3.3 --- Effect of Au catalyst --- p.3-3 / Chapter 3.4 --- Growth models --- p.3-3 / Chapter 3.5 --- Samples sintered at different temperatures --- p.3-5 / Chapter 3.6 --- Samples at different deposition zones --- p.3-6 / Chapter 3.7 --- Cathodoluminescence --- p.3-6 / Chapter 3.7.1 --- Blue shift in the deep level emission --- p.3-7 / Chapter 3.7.2 --- Intensity of the emission --- p.3-8 / References --- p.3-10 / Figures --- p.3-11 / Tables --- p.3-24 / Chapter Chapter4 --- Results and discussions part II - Asymmetric growth on the CdS ribbons / Chapter 4.1 --- Surface polarization --- p.4-1 / Chapter 4.2 --- One sided saw-teeth ribbons --- p.4-2 / Chapter 4.3 --- Two-sided comb-like ribbons --- p.4-3 / Chapter 4.4 --- Growth models for the asymmetric growth --- p.4-5 / References --- p.4-7 / Figures --- p.4-8 / Chapter Chapter5 --- Conclusions and future studies / Chapter 5.1 --- Conclusions --- p.5-1 / Chapter 5.2 --- Future studies --- p.5-2 / References --- p.5-4

Graduation date: 1994

Thesis (Ph. D.)--University of Texas at Austin, 2003. / Vita. Includes bibliographical references. Available also from UMI Company.

Not available / text

Thesis (Ph.D.)--York University, 1999. Graduate Programme in Chemistry. / Typescript. Includes bibliographical references (leaves 155-161). Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: http://wwwlib.umi.com/cr/yorku/fullcit?pNQ43453

Thesis (M.S.)--University of Delaware, 2008. / Principal faculty advisor: Robert W. Birkmire, Dept. of Materials Science & Engineering. Includes bibliographical references.

Thesis (M.Sc.)--City University of Hong Kong, 2005. / At head of title: City University of Hong Kong, Department of Physics and Materials Science, Master of Science in materials engineering & nanotechnology dissertation. On t.p. the "x" of "CdxZn₁-xS" are subscript. Title from title screen (viewed on Sept. 4, 2006) Includes bibliographical references.

The bis(2-pyridylthio)methyl ligand, [Bptm], offers a synthetically convenient alternative to a variety of multidentate ligands, including most notably [Tptm] (tris(2-pyridylthio)methyl) and [BptmSTol] (bis(2-pyridylthio)(p-tolylthio)methyl), and, in contrast with [Tptm], necessarily coordinates to metal centers in a κ³ fashion. As such, numerous [Bptm] complexes of zinc have been synthesized and structurally characterized. In Chapter 1, we describe the reaction of the protonated ligand [Bptm]H with the homoleptic zinc compounds Me₂Zn and Zn[N(SiMe₃)₂]₂ to afford, respectively, [Bptm]ZnMe and [Bptm]ZnN(SiMe₃)₂; the latter has been used as a starting point for a wide range of reactivity.Most notably, the terminal zinc hydride, [Bptm]ZnH, can be accessed via either (i) metathesis of the zinc siloxide, [Bptm]ZnOSiPh₃, with either PhSiH₃ or HBpin, or (ii) direct metathesis of the zinc amide [Bptm]ZnN(SiMe₃)₂ with HBpin; the latter reactivity is not precedented and offers a novel approach for the synthesis of molecular zinc hydrides. Both [Bptm]ZnN(SiMe₃)2 and [Bptm]ZnH provide access to a variety of monomeric derivatives, including the zinc halides [Bptm]ZnX (X = Cl, Br, I) and the zinc isocyanate [Bptm]ZnNCO; the latter can be accessed directly via (i) metathesis of [Bptm]ZnH with Me₃SiNCO or (ii) a multistep reaction of [Bptm]ZnN(SiMe₃)₂ with CO₂. [Bptm]ZnH also undergoes insertion of CO₂ into its Zn—H bond to afford the zinc formate, [Bptm]ZnO₂CH, in which the formate moiety exhibits a monodentate binding mode in the solid state. This reactivity enables it to serve as a catalyst for the hydrofunctionalization of CO₂; specifically, [Bptm]ZnH catalyzes the hydrosilylation of CO₂ by (RO)₃SiH (R = Me, Et) at elevated temperatures to afford the respective silyl formates (RO)3SiO₂CH, as well as the hydroboration of CO₂ by HBpin at room temperature to afford the boryl formate HCO₂Bpin. In the absence of CO₂, [Bptm]ZnH also catalyzes the reduction of HCO₂Bpin to the methanol level, MeOBpin. Similarly, [Bptm]ZnH serves as an effective catalyst for the hydrosilylation and hydroboration of a variety of ketones and aldehydes. In all cases, hydroboration is more facile than the corresponding hydrosilylation. The [Bptm]Zn system has been investigated computationally, and the kinetics of insertion of CO₂ into the Zn—H bond of [Bptm]ZnH as well as the thermodynamics of the catalytic cycle have been examined. Further mechanistic studies examine two noteworthy spectroscopic features of the system, namely rapid exchange (i) between the zinc and boryl formates [Bptm]ZnO₂CH and HCO₂Bpin, as well as (ii) between [Bptm]ZnH and [Bptm]ZnO₂CH. Both of these exchange processes have been investigated with variable-temperature NMR spectroscopy; in particular, the former exchange resolves at low temperatures and can be confirmed by exchange spectroscopy. In addition to the aforementioned monomeric zinc halides [Bptm]ZnX (X = Cl, Br, I), the dimeric bridging zinc fluoride {[Bptm]Zn(μ-F)}₂ has been synthesized via reaction of Me3SnF with either [Bptm]ZnN(SiMe₃)₂ or [Bptm]ZnH, as outlined in Chapter 2. The dimeric nature of the fluoride in contrast with the other monomeric halides can be attributed to the significant polarity of the Zn—F bond. {[Bptm]Zn(μ-F)}2 also reacts with Me₃SiCF₃ to afford an unusual instance of a structurally characterized zinc trifluoromethyl complex, [Bptm]ZnCF₃. Chapter 3 discusses cadmium analogues to the [Bptm]Zn system, which provide a comparison and a contrast both with their zinc counterparts as well as with previously reported [Tptm]Cd complexes. While the cadmium amide [Bptm]CdN(SiMe₃)2 may be synthesized in a manner corresponding to that for its zinc analogue, the siloxides {[Bptm]Zn(μ-OSiR₃)}₂ (R = Me, Ph) form dimers that are distinct from the monomeric [Bptm]ZnOSiPh₃ and [Tptm]CdOSiPh₃, although similar to {[Tptm]Cd(μ-OSiMe₃)}₂. The distinctions between the [Bptm]Zn and [Bptm]Cd siloxides have been investigated computationally, indicating that the cadmium species show a thermodynamic preference for dimer formation, which can be attributed to the larger atomic radius of cadmium relative to zinc. Attempts to synthesize a cadmium hydride are interrupted by a Schlenk-type equilibrium giving way to the bis(ligand) complex [Bptm]2Cd and CdH₂, which in turn decomposes to Cd and H2. However, spectroscopic studies indicate that under CO₂, [Bptm]CdN(SiMe₃)₂ and HBpin react to trap a cadmium hydride species as the bridging formate derivative, [Bptm]Cd(μ-O₂CH)₂Bpin. The interaction of nitrogen-rich ligands with main group metals is further probed in Chapter 4, which describes the investigation of the coordination of 2,2’:6,2”-terpyridine (terpy) to magnesium compounds. Most prominently, unsubsituted terpy forms an adduct, terpyMg[N(SiMe₃)₂]₂, with the monomeric form of the magnesium amide {Mg[N(SiMe₃)₂]₂}₂. The adduct reacts with halide donors to form a series of mixed amide-halide complexes, terpyMg[N(SiMe₃)]X (X = Cl, Br, I), as well as a mixed amide-azide complex, terpyMg[N(SiMe₃)₂]N₃. These complexes represent the first instances of neutral monomeric terpyMg compounds that feature unsubstituted terpyridine. Structural comparisons of these complexes with one another as well as with comparable compounds are undertaken. Complexes of terpy with cadmium and zinc analogues, terpyCd[N(SiMe₃)₂]₂ and terpyZn [N(SiMe₃)₂]₂, are explored further, and DFT calculations are used to explore the strength of the interactions between the ligand and the metals in each case. Finally, in Chapter 5, attention is given to the recently reported zinc bromide complex featuring a zwitterionic carboxylate ligand, (Cbp)2ZnBr₂. The structure reported for this complex features several anomalous features, including abnormally long Zn—Br and Zn—O bonds, unusually small atomic displacement parameters for Zn, and a high R-value. This information led us to synthesize and investigate the cadmium counterpart, (Cbp)₂CdBr₂; we find that the cadmium complex possesses nearly identical structural parameters to the reported zinc complex, and when the cadmium is refined as zinc, the displacement parameter problems are reproduced. Therefore, we conclude that the reported structure is in fact that of (Cbp)₂CdBr₂, and report a revised structure for (Cbp)₂ZnBr₂.

by Wong Kin Sang. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1998. / Includes bibliographical references (leaves 61-62). / Text in English; abstract also in Chinese. / by Wong Kin Sang. / Table of contents --- p.I / Chapter Chapter 1 --- Introduction / Chapter 1.1 --- Interest in ZnxCd1-x Se/InP --- p.1 / Chapter 1.2 --- Conditions of thermal annealing --- p.2 / Chapter 1.3 --- Advantages of using photoluminescence (PL) --- p.3 / Chapter 1.4 --- Our work --- p.4 / Chapter Chapter 2 --- Experimental setup and procedures / Chapter 2.1 --- PL measurements --- p.6 / Chapter 2.1.1 --- Setup --- p.6 / Chapter 2.1.2 --- Types of PL measurements --- p.6 / Chapter 2.2 --- Annealing experiments --- p.8 / Chapter 2.2.1 --- Setup --- p.8 / Chapter 2.2.2 --- Types of annealing --- p.10 / Chapter 2.2.3 --- Procedures --- p.11 / Chapter Chapter 3 --- Results and discussions / Chapter 3.1 --- Room temperature PL studies of ZnxCd1-xSe/InP --- p.12 / Chapter 3.1.1 --- As-grown ZnxCd1-x Se/InP --- p.12 / Chapter 3.1.1.1 --- Peak energy vs concentration --- p.12 / Chapter 3.1.2 --- Annealing studies --- p.15 / Chapter 3.1.2.1 --- Isothermal annealing --- p.15 / Chapter 3.1.2.2 --- Isochronal annealing --- p.20 / Chapter 3.2 --- PL studies of ZnxCd1-xSe/InP at 10 K temperature --- p.22 / Chapter 3.2.1 --- As-grown ZnxCd1-xSe/InP --- p.22 / Chapter 3.2.1.1 --- Excitation power density dependence --- p.22 / Chapter 3.2.1.2 --- Peak energy vs Zn concentration --- p.26 / Chapter 3.2.2 --- Annealing studies --- p.29 / Chapter 3.2.2.1 --- Isothermal annealing --- p.29 / Chapter 3.2.2.2 --- Isochronal annealing --- p.33 / Chapter 3.3 --- Temperature dependent PL studies of ZnxCd1-xSe/InP --- p.37 / Chapter 3.3.1 --- As-grown ZnxCd1-xSe/InP --- p.37 / Chapter 3.3.1.1 --- Peak energy vs temperature --- p.37 / Chapter 3.3.1.2 --- Peak width vs temperature --- p.46 / Chapter 3.3.2 --- Annealing studies --- p.50 / Chapter 3.3.1.1 --- Peak energy vs temperature --- p.50 / Chapter 3.3.1.2 --- Peak width vs temperature --- p.55 / Chapter Chapter 4 --- Conclusions --- p.59 / References --- p.61

The sizes, shapes, relaxed atomic positions, eigenvalues, and total energies are calculated for selected ultra-small CdSe clusters using SIESTA, a software package for electronic structure calculations and molecular dynamics simulations of molecules and solids. The properties of these bare clusters with small numbers of constituent atoms are studied using density functional theory (DFT) for energy calculations and the conjugate gradient approximation as well as simulated annealing type of molecular dynamics techniques in relaxing the structure to find the lowest energy configurations.The ab-initio norm-conserving pseudopotentials, the exchange-correlation approximation, and parameters used in the computations by Siesta software is verified using FHI98PP, a package used to generate and test the ab-initio norm-conserving pseudopotentials. The initial position of the atomic co-ordinates is determined using ancillary software written in Matlab. / Department of Physics and Astronomy