Thesis (Ph. D.)--Materials Science and Engineering, Georgia Institute of Technology, 2008. / Peter J. Hesketh, Committee Member ; Zhong Lin Wang, Committee Chair ; C.P. Wong, Committee Member ; Robert L. Snyder, Committee Member ; Christopher Summers, Committee Member.

Thesis (Ph. D.)--University of Chicago, 1919. / "Private edition, distributed by the University of Chicago libraries, Chicago, Illinois." "Reprinted from the Astrophysical journal, vol. LII, no. 5, December, 1920." Includes bibliographical references. Also available on the Internet.

Th. 3e cycle--Sci. nat.--Paris 6, 1975. / Bibliogr. p. 141-147.

Thesis (M.S.)--University of Missouri, School of Mines and Metallurgy, 1926. / The entire thesis text is included in file. Typescript. Title from title screen of thesis/dissertation PDF file (viewed November 20, 2009) Includes bibliographical references (p. 38).

Thesis (B.S.)--University of Missouri, School of Mines and Metallurgy, 1910. / The entire thesis text is included in file. Typescript. F. E. Riede determined to be Frederick Edward Riede and E. F. Boland determined to be Earl Frederick Boland from "Forty-First Annual Catalogue. School of Mines and Metallurgy, University of Missouri". F. E. Riede received a Bachelor of Science degree in Metallurgical Engineering and E. F. Boland received a Bachelor of Science degree in Mining Engineering. Both degrees determined from "1874-1999 MSM-UMR Alumni Directory". Title from title screen of thesis/dissertation PDF file (viewed February 27, 2009)

Thesis (M.A.)--Boston University

Nanowires of Zinc oxide and bismuth oxide were grown on silicon substrates using vapor-liquid-solid (VLS) and unbalanced magnetron sputtering. Characterization using x-ray diffraction (XRD) and scanning electron microscopy (SEM) was conducted to investigate how growth conditions influence the structural and morphological properties of the materials. Optical properties were investigated using photoluminescence (PL), direct absorption spectra and cyclic voltammetry. The physical properties of sputtered ZnO were found to be dependent on oxygen flow rate, temperature, and the initial foreign metal catalysis seed layer. Nanowires were grown using a two-step process whereby an initial Au layer was deposited followed by Zn with oxygen. Doped ZnO-TiO2 nanostructures were created by sputtering Ti and Zn simultaneously. Homo- and hetero-structured ZnO-ZnO and ZnO-TiO2 were created using additional sputtering cycles. A systematic approach was taken to produce nanoarrays of Bi2O3 by adjusting initial seed layer thickness and oxygen flow rates. A two step process involving variable oxygen flow rates was found to create the highest density of Bi2O3 nanowires in the array. Top-view and cross-sectional SEM micrographs suggested that the resulting Bi2O3 nanowires were approximately 300 nm in length with diameters of 100 nm at the base and 30 nm at the top. Investigation into the growth method suggests a self-catalytic VLS-like process. Degradation tests using rhodamine 6G dye were compared to SEM images. Samples of ZnO and Bi2O3 displayed a direct correlation between nanowire density and photocatalytic efficiency.

The synthesis of symmetrically and unsymmetrically substituted zinc phthalocyanines (ZnPc) derivatives is done according to reported procedures. The unsymmetrical ZnPc derivatives are synthesized by ring expansion of sub-phthalocyanine complexes. Ring substitution is effected with tert-butyl phenol, naphthol, and hydroxybenzoic acid. Comparison of the redox potentials for the complexes substituted with varying numbers of tert-butyl phenol: 1, 2, 3, 6 and 8 show that the complex with the highest number of substituents are more difficult to oxidize and easier to reduce. Water soluble sulphonated ZnPc (ZnPcSn) was prepared. The possibility of using axial ligation to increase the solubility and the photochemical activity of sulphotnated ZnPc in aqueous solutions was investigated. Pyridine, aminopyridyl and bipyridyl were used as axial ligands. When bipyridyl was used as the axial ligand, solubility of the ZnPcSn increased, shown by the increase in the Q-band of the monomer species in solution and the singlet oxygen quantum yields was relatively higher than that of the unligated ZnPcSn. The singlet oxygen quantum yields by the various complexes in DMF using diphenylisobenzofuran as a chemical quencher for organic solvent were determined. Singlet oxygen quantum yields for the unsymmetrically ring substituted complexes range from 0.22 to 0.68. Photobleaching quantum yields are in the order of 10-5, which means that the complexes are relatively photostable.

Substituted zinc and magnesium phthalocyanine and porphyrazine derivatives were synthesized according to the reported procedures. The magnesium and zinc phthalocyanine and porphyrazine derivatives were synthesized by ring enlargement of subphthalocyanine and statistical condensation of the two phthalonitrile derivatives. Characterization of the complexes involved the use of infrared spectroscopy, nuclear magnetic resonance spectroscopy, ultraviolet and visible spectroscopy, and Maldi-TOF spectroscopy (for selected compounds) and elemental analysis. Photochemical and photophysical properties of the complexes in non-aqueous solution was then investigated. Photobleaching quantum yields are in order of 10⁻⁵ indicating their relative photostability. Complexes containing more electron-donating substituents were more easily oxidized. For complexes 66 and 69 (as these complexes have the same number of substituents but differ in the metal center) photobleaching quantum yield for the ZincPc complex 69 was slightly less than that of the MgPc complex 66. Singlet oxygen quantum yields of the various complexes in DMSO using diphenylisobenzofuran (DPBF) as a quencher in organic solvents were determined. Singlet oxygen quantum yields of the complexes range from 0.23 to 0.67. High values of Φ[subscript]Δ ZnPc complexes was observed compared to the corresponding MgPc, complexes. This was evidenced by complexes 66 and 69 with Φ[subscript]Δ values of Φ[subscript]Δ = 0.26 and 0.40, respectively. Varying number of phenoxy substituents, complex 71 gave significantly large value of Φ[subscript]Δ compared to 70 (that is, the presence of more electron-donating substituted group, gave higher singlet oxygen quantum yields (0 .67 and 0.25 for 71 and 70 repectively). The triplet quantum yields and triplet lifetimes were determined by laser flash photolysis for selected compounds. The triplet quantum yields increase as the number of substituents increases e.g 68 > 67 > 66. Comparing porphyrazine complexes (63, 64 and 65), 63 with benzene attached to the ring, has higher triplet state lifetime (420 μs) compared to 64 and 65 containing long alkyl chain and tertbutyl substituents, 350 and 360 μs,respectively). The observed Φ[subscript]f values for 68 and 63 were quiet suprising, since low values are observed compared to the rest of the complexes (e.g 0.03 and 0.02 respectively). Although these values seem so low, they are sufficient for fluorescence imaging applications. The Φ[subscript]f values for the complexes under study are within the range reported for complexes currently used for PDT. / KMBT_363 / Adobe Acrobat 9.54 Paper Capture Plug-in

Made available in DSpace on 2014-06-11T19:29:10Z (GMT). No. of bitstreams: 0 Previous issue date: 2007-04-13Bitstream added on 2014-06-13T19:58:50Z : No. of bitstreams: 1 dochi_rs_me_araiq.pdf: 770962 bytes, checksum: 107cc3116fbd69b992c127e5b4eecb14 (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O estudo de complexos mistos contendo metais de transição e íons terras raras vêm despertando o interesse na busca de aplicações de suas propriedades ópticas em dispositivos eletrônicos. Neste trabalho foram obtidos complexos de zinco com o ligante ácido nicotínico (ácido 3-piridinocarboxílico) e também de európio com o mesmo ligante, sob condições ambientes e hidrotérmicas, bem como complexos mistos, contendo ambos os íons metálicos com o ácido nicotínico sob condições hidrotérmicas. Análises elementar e térmica permitem propor as estequiometrias de alguns complexos: [Zn(C6H4NO2)2(H2O)4] obtido a partir do Zn(C2H3O2)2.2H2O e do ligante tanto sob condições ambientes como sob condições hidrotérmicas, [Eu(C6H4NO2)3(H2O)2] obtido tanto sob condições ambientes a partir do EuCl3 e do ligante, como a partir do Eu2O3 e do ligante sob condições; provavelmente [Zn2Eu(C6H4NO2)7(H2O)10] a partir dos complexos dos respectivos íons metálicos obtidos sob condições hidrotérmicas; uma mistura de complexos foi obtida a partir dos óxidos dos íons metálicos; e a utilização dos sais levou à formação do [Zn(C6H4NO2)2(H2O)4]. Assim, tanto a escolha dos reagentes de partida, como o método de preparação são determinantes para obtenção dos produtos. Os resultados das espectroscopias vibracional na região do IV e de absorção no UV-Vis permitem concluir que no complexo de zinco, [Zn(C6H4NO2)2(H2O)4], obtido a partir dos sais independentemente das condições, o ligante está coordenado ao íon zinco através do nitrogênio. Já no complexo de európio, [Eu(C6H4NO2)3(H2O)2], o ligante coordena-se ao íon európio através do grupo carboxilato de modo bidentado. A espectroscopia de luminescência sugeriu que há transferência de energia do ligante para o íon emissor e que a simetria ao redor do íon európio é baixa tanto no complexo de európio como no misto de európio e zinco. / Single zinc or europium complexes with the ligand nicotinic acid (3-piridinocarboxilic acid) were either obtained under laboratory or hydrothermal conditions, and also mixed ion complexes of both zinc and europium ions and nicotinic acid under hydrothermal condition. Elementary and thermal analyses allow to propose the stoichiometries of somcomplexes: [Zn(C6H4NO2)2(H2O)4] obtained from Zn(C2H3O2)2.2H2O and the ligand either under room or hydrothermal conditions, [Eu(C6H4NO2)3(H2O)2] obtained either under room conditions using EuCl3 and ligand, or by using Eu2O3 and ligand under hydrothermal conditions, and probably [Zn2Eu(C6H4NO2)7(H2O)10] obtained from metallic complexes under hydrothermal conditions. The use of respective oxides and ligand as departure reagents under hydrothermal condition results in mixed compounds. Therefore, the choice of the departure reagents and the method of preparation are very important. Vibrational absorption in the infrared region and absorption in the ultraviolet and visible region spectroscopies allowed concluding that in the [Zn(C6H4NO2)2(H2O)4] complex the ligand is coordinated to the zinc by the nitrogen atom independent of the preparation method. On the other hand, in europium complex, [Eu(C6H4NO2)3(H2O)2], the carboxilate group of the ligand is bidentate. Luminescence spectroscopy results infer that there is an energy transfer from ligand to europium, as well as the local europium ion symmetry is small both for simple complex and for mixed europium and zinc one.