Thesis (Chemistry)--Vanderbilt. / Typescript.

Thesis (B.S.)--University of Missouri, School of Mines and Metallurgy, 1898. / The entire thesis text is included in file. Typescript. Title from title screen of thesis/dissertation PDF file (viewed November 18, 2008)

Thesis (Ph. D.)--University of Wisconsin--Madison, 1960. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 117-121).

Thesis (Ph. D.)--University of Wisconsin--Madison, 1936. / Typescript. Includes abstract and vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Como extensão de um trabalho recentemente iniciado em nosso laboratório, foram preparados tetrahalogenoarilteluratos (IV) de amônio, sulfônio, selenônio, arsônio e iodônio. Os compostos foram obtidos tratando-se os trihaletos de ariltelúrio com haletos de amônio, sulfônio, selenônio, arsônio e iodônio em solvente orgânico. Os mesmos compostos podem ser preparados empregando-se ácidos halogenídricos como meio reagente. Reações de troca iônica foram efetuadas, permitindo a interconversão dos ânions complexos. Reações com resinas trocadoras de íons e medidas de condutância molar apoiam a natureza iônica dos compostos. A estrutura do ânion foi discutida de acordo com a teoria das repulsões entre os pares de elétrons da órbita de valência. A simetria C4v foi sugerida, apoiada em dados espectroscópicos infravermelho e Raman em estado sólido e em solução. / As a continuation of recently initiated work in our laboratory, ammonium, sulphonium, selenonium, arsonium and iodonium tetrahaloaryltellurates (IV) have been prepared. The compounds were obtained by treating the aryltellurium trihalides with ammonium, sulphonium, selenonium, arsonium and iodonium halides in organic solvents. The same compounds were also prepared using aqueous hydrogen halides as the reagent media. Halogen exchange reactions have been performed thus permitting the interconversion of the complex anions. Reactions on ion exchange resins and conductance measurements support the ionic nature of the compounds. The anion structure is discussed according to the valence shell eletron pair repulsion theory. The C4v symmetry is suggested for the anion supported by infrared and Raman spectral data in solid state and in solution.

Como extensão de um trabalho recentemente iniciado em nosso laboratório, foram preparados tetrahalogenoarilteluratos (IV) de amônio, sulfônio, selenônio, arsônio e iodônio. Os compostos foram obtidos tratando-se os trihaletos de ariltelúrio com haletos de amônio, sulfônio, selenônio, arsônio e iodônio em solvente orgânico. Os mesmos compostos podem ser preparados empregando-se ácidos halogenídricos como meio reagente. Reações de troca iônica foram efetuadas, permitindo a interconversão dos ânions complexos. Reações com resinas trocadoras de íons e medidas de condutância molar apoiam a natureza iônica dos compostos. A estrutura do ânion foi discutida de acordo com a teoria das repulsões entre os pares de elétrons da órbita de valência. A simetria C4v foi sugerida, apoiada em dados espectroscópicos infravermelho e Raman em estado sólido e em solução. / As a continuation of recently initiated work in our laboratory, ammonium, sulphonium, selenonium, arsonium and iodonium tetrahaloaryltellurates (IV) have been prepared. The compounds were obtained by treating the aryltellurium trihalides with ammonium, sulphonium, selenonium, arsonium and iodonium halides in organic solvents. The same compounds were also prepared using aqueous hydrogen halides as the reagent media. Halogen exchange reactions have been performed thus permitting the interconversion of the complex anions. Reactions on ion exchange resins and conductance measurements support the ionic nature of the compounds. The anion structure is discussed according to the valence shell eletron pair repulsion theory. The C4v symmetry is suggested for the anion supported by infrared and Raman spectral data in solid state and in solution.

Thesis (M.S. in Chemistry)--University of California, Berkeley, Sept. 1957. / Includes bibliographical references (leaf 23).

A study of the growth of monocrystals of tellurium and selenium-tellurium alloys by the Czochralski method has been made, together with measurements of the photoconductivity in such materials. In tellurium, it was found that large temperature gradients occur within a growing ingot which cause an increase in the concentration of lattice defects. This concentration can be reduced by subsequent annealing. An etch pit orientation effect was observed enabling the growth direction of an ingot to be determined, arising from a correspondence between preferential growth and etching planes. Photoconductivity in tellurium at 77 K was found to be decreased by abrasive polishing of the samples and increased by annealing. Transient photoconductivity was found to be characterized approximately by two time constants, one of the order of microseconds and the other tens of microseconds. The largest D* detectivity measured on the samples was 1.3 x 10('11) cm Hz(' 1/2)w('-1) at 3.5 (mu)m. Crystals of Se(,x)Te(,1-x) were prepared by the Czochralski method for Te-rich and Se-rich compositions with 0.1 > x > 0.95. For intermediate compositions with 0.1 < x < 0.95 it was not possible to obtain Czochralski-ingots due to a meniscus rupture problem arising from excess selenium at the growing interface. In this case crystallographically aligned samples were obtained by a slow cooling method. Measurements on the Se(,x)Te(,1-x) alloys showed a continuous wavelength displacement of the photoconductivity maximum from 3.7 to about 0.8 (mu)m in going from tellurium to selenium. This was accompanied by an increase of some 5 orders of magnitude in the photoresponse, in the photoconductive decay time constants and in the electrical resistivity. From the results the estimated energy gaps were found to change continuously from tellurium to selenium with a possible change of slope starting near 40 at.% Se.

No description available.

published_or_final_version / Physics / Master / Master of Philosophy