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Gas phase thermochemistry of organogermanium compounds (open access)

Gas phase thermochemistry of organogermanium compounds

A variety of silyl- and alkyl-germylene precursors have been synthesized and subsequently pyrolyzed in the gas phase. Arrhenius parameters were obtained employing a pulsed-stirred flow reactor for these unimolecular decompositions. These precursors are divided into two major categories by mechanism of germylene extrusion: {alpha}-elimination precursors and germylacetylenes. The extrusion of germylenes from germylacetylene precursors is of primary interest. A mechanism is proposed employing a germacyclopropene intermediate. Evidence supporting this mechanism is presented. In the process of exploring germylacetylenes as germylene precursors, an apparent dyatropic rearrangement between germanium and silicon was observed. This rearrangement was subsequently explored.
Date: December 7, 1993
Creator: Engel, J. P.
System: The UNT Digital Library
Topics in electroweak baryogenesis: The sphaleron and t-violation (open access)

Topics in electroweak baryogenesis: The sphaleron and t-violation

Assuming that beyond the standard model physics can be parametrized in terms of high dimensional operators, we examine their effects on the energy of the sphaleron and the classical solution of the gauge and Higgs fields. In the absence of fermions, all of the six dimension 6 operators which are SU(2) symmetric have a small effect when calculated perturbatively. However, calculated non-perturbatively, one of the operators alters the boundary conditions of the equations of motion of the Higgs and gauge fields involved, and another operator gives rise to an abrupt change in the sphaleron energy at a small but definite Higgs quartic coupling. The magnitude of the T-violating muon polarization induced by electromagnetic final state interaction in the radiative Kaon decay K{sup +} {yields} {mu}{sup +}{nu}{mu}{gamma} is order of 10{sup {minus}3}.
Date: December 7, 1993
Creator: SeungKoog, L.
System: The UNT Digital Library
Fundamental studies of hydrogen interaction with supported meta and bimetallic catalysts (open access)

Fundamental studies of hydrogen interaction with supported meta and bimetallic catalysts

The thesis is divided into 3 parts: interaction of H with silica supported Ru catalysts (high pressure in situ NMR), in situ NMR study of H interaction with supported Ru-group IB bimetallic catalysts, and in-situ NMR study of H effects on silica-supported Pt, Rh and Ru catalysts.
Date: December 7, 1993
Creator: Bhatia, S.
System: The UNT Digital Library
Terfenol: A study of the phase equilibrium diagram and the solidification process (open access)

Terfenol: A study of the phase equilibrium diagram and the solidification process

Terfenol is a rare earth-iron alloy that was first developed at the Naval Ordinance Laboratory because of its rare magnetostrictive properties. Terfenol is composed of terbium and dysprosium combined with iron in a composition Tb{sub x}Dy{sub 1{minus}x}Fe{sub 2}, where x{approximately}0.3. The objective of this work was to determine the growth characteristics of Terfenol and its dependence on solidification rate, temperature gradient, and stoichiometry. Specific goals of this work were to verify the phase equilibria that is currently accepted for the systems DyFe{sub 2} and TbFe{sub 2}, and establish the phase equilibria near the composition Tb{sub 0.3}Dy{sub 0.7}Fe{sub 2}; establish that Terfenol grows directly from the liquid and that the reaction is occurring under metastable conditions; evaluate whether or not Terfenol can be grown under plane front conditions with a new radiofrequency float zone apparatus, and; determine whether or not <111> seeded crystals can be grown and <111> single crystals produced by elimination of dendrites employing growth methods capable of achieving high gradient/solidification rate ratios.
Date: December 7, 1993
Creator: Anderson, M.
System: The UNT Digital Library