Thesis (Ph. D.)--University of Wiscosnin--Madison, 1981. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 204-209).

Studying quasi-one-dimensional (1D) semiconductor nanostructures is an attractive and active research field in nanoscience and nanotechnology. Their controllable growth is the foundation for observing novel properties and fabricating useful nano-devices and is also a challenge. / We believe that our work in perfecting the fabrication of aligned 1D semiconductor nanostructures and control of their morphology, crystal structure and orientation will shed more light on the understanding on 1D physics and advancement in nanotechnology. / We have studied the control of the structure, morphology and alignment of Zn-Cd-Se 1D nanostructures by fine tuning their growth conditions and judiciously choosing substrates in a metalorganic chemical vapor deposition (MOCVD) reactor. We found that the products are zincblende structured nanoneedles at relatively low temperatures and pressures, and wurtzite structured nanowires at high temperatures and pressures. We have fabricated aligned 1D nanostructures of different chemical compositions by exploiting the epitaxial relationship between the lattices of Zn-Cd-Se system and GaAs substrate. From the systematic studies of the orientations of the aligned samples, we demonstrated that they can be controlled by the crystallographic surface of the substrate. We also found that the orientation can be affected by the growth temperature. Three growth models are suggested to explain the aligned growth for zincblende and wurtzite 1D nanostructures and complex shaped three-bladed nanoswords. Observations and angular measurements of the orientations and growth directions by electron microscopy and analyses by pole stereographs offer supporting evidences for the models. Polarized photoluminescence studies of individual CdSe nanowires obtained under controlled growth have been achieved. / Liu, Zhuang = 通過金屬有機物化學氣相沉積法合成晶體結構, 形貌及生長取向性可控的硒鋅鎘族准一維納米結構 / 劉壯. / "July 2007." / Adviser: Sui Kong Hark. / Source: Dissertation Abstracts International, Volume: 69-02, Section: B, page: 1062. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2007. / Includes bibliographical references. / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract in English and Chinese. / School code: 1307. / Liu, Zhuang = Tong guo jin shu you ji wu hua xue qi xiang chen ji fa he cheng jing ti jie gou, xing mao ji sheng chang qu xiang xing ke kong de xi xin ge zu zhun yi wei na mi jie gou / Liu Zhuang.

Les hétérocycles aromatiques sont des motifs structuraux rencontrés dans un grand nombre de substances d'intérêts biologiques ou pharmacologiques. Plus particulièrement, les pyridazines substituées font l'objet d'un intérêt grandissant pour leurs propriétés pharmaceutiques (antibactériens, anti-inflammatoires, médicaments cardiovasculaires…). De plus, les structures comportant des pyridazines peuvent également être utilisées en tant qu'agents chélatants de cations métalliques et s'ordonner en édifices utilisés en chimie supramoléculaire.Nous nous sommes donc intéressés à l'élaboration d'éléments de base comportant des cycles pyridaziniques de type aryl ou hétéroarylpyridazines. La mise au point de méthodes impliquant des espèces organométalliques a été l'un de nos objectifs primordial. L'élaboration de ces composés a été réalisée par formation de liaisons C-C. Une approche électrochimique d'hétérocouplage associé à une catalyse au nickel a été utilisée. Quelques limites à cette méthode ont cependant été observées dans le cas des couplages mettant en jeu des 3,6-dihalogénopyridazines. Une étude par électrochimie analytique a permis d'en comprendre les raisons. La seconde partie de notre travail a consisté en l'étude de la réactivité d'arylzinciques ou de triarylbismuths vis-à-vis de 3,6-dihalogénopyridazines / Heteroaromatic rings are present in various biological and pharmacological active molecules. Substituted aryl-pyridazines have given rise to considerable interest because of their diverse pharmacological properties (antibacterial, anti-inflammatory, cardiovascular drugs…). Moreover, structures which contain pyridazines are used in supramolecular chemistry for their applications through self-assembly processes in the presence of metal ions.In order to elaborate building blocks containing pyridazine rings such as aryl or heteroaryl-pyridazines, we turned our intention on the development of complementary methods involving organometallic reagents. Transition metal-catalyzed cross-coupling reaction of organometallic compounds with organic halides is one of the most powerful methods for the generation of C-C bonds.We chose to develop the most straightforward method involves heterocoupling reaction of aryl/heteroaryl compounds under electrochemical conditions (sacrificial anode process) associated to a nickel catalysis. However some limitations have been pointed out when 3,6-dihalogenopyridazines are involved in the cross-coupling reaction. An electrochemical study was investigated in order to propose some mechanistic considerations. A second part of this work consisted in the study of arylzinc and triarylbismuths reagents toward 3,6-dihalogenopyridazines

Zinc dialkyldithiophosphates (ZDTPs) are widely incorporated in lubricant formulations as anti-oxidant and anti-wear additives. Recent years have seen the emergence of considerable research aimed at defining the mode of action of these compounds. Despite this, the mechanistic action of ZDTPs in their capacity as both anti-wear and anti-oxidant agents remains ill defined. Previous investigations have used a wide variety of techniques, however, electrochemical methods have been poorly exploited. This thesis describes application of electrochemical techniques to the study of zinc ndibutyldithiophosphate (Buⁿ-ZDTP) in an investigation of the value of such methods as a tool for ZDTP analysis. A comprehensive study of Bun-ZDTP redox activity under standard electrochemical conditions has been implemented. Using cyclic voltammetry, Buⁿ-ZDTP has been shown to be oxidised in an irreversible 2 electron transfer process. The diffusion coefficient of this species in DMF has been calculated via rotating disc electrode (RDE) voltammetry. Buⁿ-ZDTP reduction proceeds via nucleation of zinc at the electrode surface. The limiting current of the 2 electron reduction process is lower than previously observed for Buⁿ- ZDTP oxidation. This occurs since zinc deposition is confined to growth centres which effectively limit the electroactive area of the electrode. A more thorough investigation of zinc nucleation at the electrode surface was undertaken using chronoamperometry. Transients plotted in dimensionless form were compared to theoretical models of nuclear growth. The potential of atomic force microscopy as a promising technique for the imaging of ZDTP filming action has been demonstrated. Ex-situ atomic force microscopy was conducted of electrode surfaces following reduction in Buⁿ-ZDTP solution under cyclic and RDE voltammetric conditions. Development of a variable elevated temperature apparatus for the study of Buⁿ-ZDTP under conditions more typical of an engine environment has been described. Application of the system to a wide range of electrochemical problems was demonstrated as an illustration of the advantages of this novel experimental approach. Studies of N, N, N/, N/-tetramethyl-p-phenylenediamine and tris(4-bromophenyl)amine oxidation yielded diffusion co-efficients (D) at elevated temperatures from which activation parameters for diffusion were obtained. Variation of D with temperature was compared to predicted theory according to the Stokes-Einstein and Wilke-Chang relationships. Studies of ortho-bromonitrobenzene and 9-chloroanthracene reduction demonstrated the elevated temperature apparatus to be a viable method for the interrogation of rapid kinetic processes. Both compounds are reduced according to an ECE mechanistic scheme where halide bond cleavage constitutes the chemical step. Since the use of microelectrodes permits "outrunning" of bond cleavage kinetics to give an n_eff of less than two, rate constants at varying temperatures were evaluated. Arrhenius plots were used to deduce activation parameters of halide bond cleavage in both compounds. Preliminary studies of Buⁿ-ZDTP redox activity under conditions more typical of an engine environment are discussed. Application of the novel microelectrode apparatus to an elevated temperature study of Buⁿ-ZDTP is described. Voltammetric investigations in toluene, a resistive solvent which serves as a convenient model for oil, are discussed.