Browsing by Subject "Rhenium"
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Item A study of oxime chelates of rhenium(Texas Tech University, 1968-06) Grayson, Phillip WarrenNot availableItem Determination of rhenium with pyridine based oximes(Texas Tech University, 1965-05) Gore, Ronald HenryThe objective of this thesis is, first, to survey the pre-Byron Don Juan, as well as to analyze the Byronic figure and story; then, to assess the influence of Byron on his followers. The thesis idea is that Lord Byron has had a distinct and formative impact on both stories and characterizations of Don Juan published since the 1820's.Item Item Neutron transmissions, capture yields, and resonance parameters in the energy range of 0.01 eV to 1 keV in rhenium(2013-12) Epping, Brian Edward; Landsberger, Sheldon; Leinweber, GregoryThe focus of this thesis is to improve upon the existing neutron cross section data for rhenium (Re) in the energy range 0.01 eV to 1 keV. Neutron transmission and capture yield measurements were performed using natural rhenium samples at the Rensselaer Polytechnic Institute Gaerttner Linear Accelerator Center. Measurements were performed using the time of flight method, in which neutron energies are differentiated using the elapsed times between neutron emission from a pulsed neutron source and the subsequent detector interactions. Transmission measurements were performed using ⁶Li glass scintillation detectors. Capture measurements were performed utilizing a 16-segment NaI(Tl) multiplicity detector. Most measurements were performed at a flight path length of 25 meters, with one set of experiments (thermal transmission) performed at 15 meters. The experiments used several metallic, elemental rhenium samples of various thicknesses, ranging from 1 mil to 100 mils. (1 mil = 0.001 inch = 0.0254 mm) Following the reduction of the experimental data, SAMMY was used to perform the data analysis. SAMMY is a shape-fitting Bayesian analysis code that determines resonance parameters by fitting neutron time of flight data using the Reich-Moore approximation of R-matrix theory. The combined transmission and capture yield data analysis determined resonance parameters for rhenium resonances in the energy range of 0.01 eV to 1 keV. The updated rhenium resonance parameters are compared to previously published parameters and ENDF/B-VII.1.Item Oligothiophenes and conducting metallopolymers : fundamental studies and development of functional materials(2013-05) Lytwak, Lauren Ashley; Holliday, Bradley J.Diimine rhenium(I) tricarbonyl complexes are known as phosphorescent emitters and electro- and photocatalysts for the reduction of CO₂ to CO. Conducting metallopolymers containing this rhenium(I) moiety should not only retain the photoluminescent and catalytic properties of the complex but also gain the conductivity, processability, and mechanical flexibility typical of [pi]-conjugated polymers. A series of tricarbonyl rhenium(I) diimine-type monomers and metallopolymers have been prepared. Appended to the ligands are thiophene and 3,4-ethylenedioxythiophene (EDOT) groups for electropolymerization of the metal complexes. UV-Vis absorption and emission spectroscopy studies of the monomers indicate that light emission originates from triplet ligand-centered (³LC) [pi] [right arrow] [pi]* and triplet metal-to-ligand charge transfer (³MLCT) excited states. Additionally, both the monomers and metallopolymers show electrocatalytic activity towards the reduction of CO₂ to CO. Furthermore, the EDOT-functionalized diimine-type ligand (EDOT₂-BPP) also serves as a good sensitizing ligand for luminescent lanthanide emission. A series of lanthanide complexes that utilize tris([beta]-diketonates) and EDOT₂-BPP ligands have been synthesized and studied using X-ray crystallography and photophysical techniques. Large quantum yields and microsecond lifetimes were found for the EuIII and SmIII complexes. Complexes of TbIII were found to have weak luminescent emission due to the less-than-optimal energy gap between the sensitizing ligands and the excited state of the TbIII ion. Oligothiophenes are models for polymeric systems because of solution processability, controlled chain length, and a well-defined structure. We have synthesized a library of alkyl and polyfluoroalkyl-substituted oligothiophenes to study how molecular structure, long-range order, spatial orientation, and varying degree of electronic coupling between molecules influences charge separation in photovoltaics. These oligoalkylthiophenes have been characterized by X-ray diffraction, photophysical methods, electrochemistry, and UV-Vis and EPR spectroscopies. Although the electronic properties of these oligoalkylthiophenes do not vary with alkyl group, aggregates of oligooctylthiophene, made through solution processing, have distinct morphologies with varying amounts of electronic disorder. The extent of electronic disorder within the aggregate is determined by comparing the suppression of the 0-0 vibronic band in the fluorescence spectra to that of the non-aggregated parent molecule. This extent of electronic disorder was correlated with the local contact potential of individual aggregates through Kelvin probe force microscopy (KPFM) measurements.Item Research and engineering towards the ITFET : graphene heterostructure dielectrics and rhenium based transistors(2016-05) Corbet, Christopher Michael; Banerjee, Sanjay; Tutuc, Emanuel, 1974-; Register, Leonard F; Colombo, Luigi; Shih, Chih-Kang KenAs semiconductor device sizes continue to scale downwards, performance degradation associated with quantum mechanical effects become a greater problem. With this, continuing the path along Moore’s Law has become more difficult and paradigm shifting technologies have begun to gain traction in device research communities. One such device is the interlayer tunneling field effect transistor (ITFET) which harnesses quantum mechanical tunneling between two channel materials separated by a thin dielectric. These devices are created from two dimensional Van der Waals crystals stacked into layered heterostructures using advanced semiconductor manufacturing techniques. The pages hereafter represent the research and engineering towards an ITFET focusing on graphene, graphene dielectrics, and Rhenium based transition metal dichalcogenides (TMDs). We begin with a zeroth order investigation of the system by creating backgated devices of two partially overlapped graphene crystals and extracting the interlayer contact resistance. We show that the interlayer contact resistance is small, localized to tunneling ‘hot-spots,’ and that overall device performance is dependent on the characteristics of both graphene layers. To continue we investigate a similar device but with a dielectric deposited between the two via atomic layer deposition (ALD) and physical vapor deposition (PVD). Innovative fabrication techniques were created and allowed for the fabrication of dozens of devices simultaneously. Moving forward, we show that the seed layer in the ALD / PVD process is incompatible with ITFET device physics. The TiO2 seed layer in this process shows Fowler-Nordheim tunneling, Poole-Frenkel tunneling, and thermionic emission through the tunnel barrier at all thicknesses, electric fields, and temperatures. To conclude we investigate the Rhenium based TMDs, ReS2 and ReSe2, as a channel material for an ITFET by analyzing their performance metrics as field effect transistors (FETs). Topgated ReS2 devices were created and showed current saturation, voltage gain, and performance metrics on par with many of the more widely researched TMDs. Backgated ReSe2 devices showed current saturation, low contact resistances, ambipolar conduction, and similar performance capabilities to the ReS2 devices. Both materials may prove an interesting channel material for optoelectronic and novel logic devices.Item The ammonolysis of rhenium (III) bromide and rhenium carbonyl(Texas Tech University, 1966-08) Foster, Ronnie EdwinNot availableItem The ammonolysis of rhenium (III) chloride and rhenium (III) bromide(Texas Tech University, 1965-05) Booker, James LutherThe reactions of rherium(III) chloride and rhenium (III) bromide in liquid ammonia have been only briefly investigated; it is reported that each of these compounds forms a series of ammoniates which are stable to ammonolysis (1). Futher investigation of the reactions of these compounds would, in large part, depend upon the accuracy of these observations.Item