Th. 3e cycle--Ethnol.--Paris 7, 1986.

Diss.--München--Hochschule für Philosophie, 1994. / Bibliogr. p. 465-475.

Magisterarbeit--Institut für Theater-, Film- und Fernsehwissenschaft--Köln--Universität, 1988. / Bibliogr. p. 119-120. Index.

Thesis (Ph. D.)--Lehigh University, 2000. / Includes vita. Includes bibliographical references (leaves 199-209).

Diss.--Berlin--Hochsch. der Künste, 1995. / Bibliogr. p. 319-327.

Thesis (Ph. D.)--Lehigh University, 2000. / Includes bibliographical references and vita.

A review of phthalocyanine materials is presented, their history, properties, applications, and potential. The two materials under investigation in this thesis (A410 H[2] and A40iso6 H[2]) are introduced as metal free, non-peripheral octa-substituted phthalocyanines, molecularly engineered for Langmuir-Blodgett deposition by M. Cook at the University of East Anglia. The Langmuir-Blodgett method is used to deposit the two materials in the Y-form, onto substrates of glass and gold plated glass, and on quartz with interdigitated platinum electrodes. Optical absorption spectra are obtained for the materials, and the linear relation between the absorption intensity and thickness confirmed. The variation in optical absorption with polarisation and angle of incidence is used to obtain the molecular orientation of the two phthalocyanines. The polarisation results confirm earlier observations. The molecular orientation angles (with respect to the substrate) obtained in this thesis are novel for these materials, and confirm the Herringbone alignment of molecular pairs. Surface Plasmon resonance is used to obtain a refractive index of 1.629, and a thickness of 17.2 nm for a 6 layer film of the A410 material. The electrical properties were measured using samples of the film deposited on substrates with interdigitated electrodes. The spectral photocurrent, conductivity, and activation energy under illumination were investigated for both materials. The electrical response of the films to temperature, voltage and gaseous environment is presented with the time dependent photocurrent response. The characterisation measurement techniques are discussed and suggestions for improvements and further work are made.

In this thesis, the potential of all-spinel oxide tunnel junctions in the field of spintronics has been investigated. In particular, the suitability of the metallic and superconducting LiTi2O4 as non-magnetic electrode in an almost defect-free CoFe2O4-based spin-filter tunnel junction has been explored. For this purpose, high-quality spinel LiTi2O4 and CoFe2O4 thin films have been deposited by pulsed laser deposition on MgAl2O4 substrates. Both films were extensively characterised in terms of structural, surface, magnetic and transport properties. The LiTi2O4 showed metallic and superconducting properties, and the CoFe2O4 had insulating and ferromagnetic properties. A careful tuning of the different growth conditions of these oxides followed in order to grow CoFe2O4/LiTi2O4 bilayers in which LiTi2O4 maintains its metallic and superconducting properties and CoFe2O4 its insulating ferromagnetic characteristics. Transport measurements at low temperature have been carried out to explore details of the tunnelling in symmetric tunnel junctions of the form LiTi2O4/CoFe2O4/LiTi2O4. The measured current–voltage characteristics of these junctions revealed clear Josephson junction behaviour due to superconductivity of the LiTi2O4 electrodes. This conclusive evidence of the tunnel nature of these junctions proves that LiTi2O4 can be used as bottom electrode in all-spinel oxide tunnel junctions.

This thesis reports a study of certain aspects of ion beam mixing in amorphous silicon. The amorphous silicon films are deposited by RF sputter deposition technique, and heavy metal markers of gold and tantalum are used to section these films. Mixing in the amorphous silicon films is brought about by energetic argon ions of various energies (100 keV to 300 keV) and an estimate of mixing is made by observing the shift and broadening in the marker profile using Rutherford backscattering spectrometry. Mixing versus depth as a function of the angle of incidence is investigated experimentally, by implanting at ten different angles (0° to 85°), films, with the marker at various depths. A comparison of the experimental results is made with the Wilson and Webb model, the average diffusion model, and a computer simulation code TRIM-Cascade. All the comparisons show evidence of radiation enhanced diffusion in the experiment. The presence of radiation enhanced diffusion is confirmed when a double marker technique is employed to determine the effect of sputtering, contraction and swelling, in an amorphous silicon film, due to mass transport under argon ion irradiation, both at room temperature and at LN2 temperature. Finally, as an application of the ion beam mixing process, silicide formation at the interface of a Ni-Si and an Fe-Si system is considered. The need to form useful silicides is evident from the recent developments in VLSI technology where transition metal silicides have been explored for interconnect metallization, gate metallization and low resistivity contacts. In the research work presented here, it is found that both the Ni-Si and Fe-Si systems show cascade type of mixing but silicide formation is more evident in the Ni-Si system.

Orientador: Carlos Frederico de Oliveira Graeff / Banca: Monica Alonso Cotta / Banca: Fenelon Martinho Lima Pontes / Resumo: A síntese DMSO foi proposta a cerca de seis anos e o resultado mais importante foi o fato da melanina obtida ser solúvel em DMSO o que permitiu a produção de filmes finos de alta qualidade. Para tal fim, a L-Dopa foi utilizada como reagente principal, em sínteses onde se variou: a concentração de perióxido de benzoíla e a concentração de água no DMSO. A síntese em água foi realizada para fins de comparação. A síntese em DMSO apresentou-se mais lenta em comparação a síntese de melanina em água através dos resultados obtidos pela técnica UV-Vis. O peróxiso de benzoíla tem influência significativa na síntese, agindo diretamente na oxidação do DMSO e na oxidação da L-Dopa. Teste de solubilidade com diferentes solventes foi realizado nas amostras de H2O-melanina, DMSO-melanina recém sintetizada e DMSO-melanina envelhecida com tempo de estocagem de quatro anos. Os solventes utilizados foram; água, DMSO, DMF, THF, acetonitrila e acetato de etila. Os resultados mostraram a insolubilidade da H2O-melanina e da DMSO-melanina envelhecida em todos os solventes e somente a solubilidade da DMSO-melanina recém sintetizada no solvente DMSO foi observada. Indicando novamente que as amostras possuem estruturas diferentes e que a DMSO-melanina sofre alterações estruturais quando exposta no ar. Nos espectros da FTIR, grupos sulfonados só foram observados na DMSO-melanina recém sintetizada, que desapareceram nas amostras envelhecidas, e que não estão presentes na H2O-melanina. Ou seja, os grupos sulfonados responsáveis pela solubilidade da DMSO-melanina com o passar do tempo sofrem degradação e saem da estrutura da DMSO-melanina, explicando assim a insolubilidade da amostra de DMSO-melanina envelhecida. O mesmo foi observado para os espectros de 13C RMN. Para entender esse processo de degradação utilizamos o NaOH2 cuja a ação é a retirada dos grupos... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Synthesis in DMSO was proposed about six year and the most important result was the fact that it is soluble in DMSO which allowed the production of thin films of high quality. To this end, the L-Dopa was used as primary reagent in primary reagent in syntheses where varied: the concentration of benzoyl peroxide and water concentration in DMSO. The synthesis was carried out in water for comparison purposes. The synthesis presented in DMSO is slower than the synthesis of melanin in water for analysis of the results obtained with the technique of UV-vis. When we analyzed the effect of the concentration of benzoyl peroxide in the synthesis, we found that the concentration of 0.5 moles of benzoyl peroxide gave summary more efficient to malanin in DMSO. Benzoyl peroxide has significant influence on the synthesis, acting directly on the oxidation of DMSO and the oxidation of L-Dopa. Solubility test was carried out with different solvents in the samples of H2O-melanin, DMSO-melanin newly synthesized and old DMSO-melanin with storage time of four years. The solvents used were: water, DMSO, DMF, THF, acetonitrile and ethyl acetate. The results showed the insolubility of H2O-melanin and old DMSO-metanin in all solvents and only the solubility of newly synthesized DMSO-melanin in the solvent DMSO was observed. Indicating again that the samples have different structures and that the DMSO-melanin undergoes structural changes when exposed to air. In FTIR, sulphonated groups were only observed in DMSO-melanin newly synthesized, which disappeared in the old samples, which are not present in the H2O-melanin. That is, the sulfonated groups responsible for the solubility in DMSO-melanin suffer degradation over the time and leave the structure of DMSO-melanin, thus explaining the insolubility of old DMSO-melanin. A chemical model was proposed, using tools... (Complete abstract click electronic access below) / Mestre