You limited your search to:

  Partner: UNT Libraries
 Department: Department of Chemistry
 Collection: UNT Theses and Dissertations
A Quantitative Study of the Common Metals Found in the Oak and the Pine

A Quantitative Study of the Common Metals Found in the Oak and the Pine

Date: August 1938
Creator: Moore, Carver Yates
Description: The purpose of this study is to determine the amounts of the element sulfur, phosphorus, sodium, potassium, silicon, iron, aluminium, calcium, magnessium, and manganess found in the roots, hearts, sap, leaves, and bark of two plants, the short leaf pine and the blackjack oak.
Contributing Partner: UNT Libraries
Modeling Transition Metal Chemistry for Catalytic Functionalization of Molecules

Modeling Transition Metal Chemistry for Catalytic Functionalization of Molecules

Date: August 2011
Creator: Morello, Glenn
Description: The diversity of transition metal complexes allows for a wide range of chemical processes to be mediated by the metal, from catalysis to surface chemistry. Investigations into the structure and electronic configuration of transition metal complexes allow for tuning of desired species by modifications to the ligands and/or metals to achieve more efficient thermodynamics and kinetics for the process of interest. Transition metals, often used in catalysts for a number of important processes, require detailed descriptions of intermediates, transition states and products to fully characterize a reaction mechanism(s) in order to design more active and efficient catalysts. Computational investigations into inorganic catalysts are explored with the aim of understanding the activity of each species and how modifications of supporting ligands, co-ligands and metals vary the interaction along the reaction pathway. Reported results give important insight into the development of the most active complexes in addition to determining the least active complexes to aid experimental development. This report first investigates the mechanisms of two unique transfer reactions: 1) formation of low coordinate nickel-nitrene ((P~P)Ni=NR; P~P = 1,2-bis(dihydrophosphino)-ethane or 1,2-bis(difluoromethylphosphino)-ethane) complexes as catalysts for nitrogen atom transfer and 2) oxidation of a triphosphorus niobium complex, [(η2-P3SnPh3)Nb(OMe)3], for the transfer of the phosphorus ...
Contributing Partner: UNT Libraries
Molecular Dimensions

Molecular Dimensions

Date: August 1938
Creator: Moss, H. H.
Description: This study attempts to calculate the areas of the cross section and diameter of the CH3 group, COOH group, the length of the carbon chain, and the longtiudinal distance between carbon atoms for each of the three acids. It also attempts to develop a method of measuring the effective diameter of molecules of gases. Equations for these terms as given by MacDougall and experiments were performed and the data applied to the equation.
Contributing Partner: UNT Libraries
Investigation of the Pressure Dependence of SO3    Formation

Investigation of the Pressure Dependence of SO3 Formation

Date: December 2003
Creator: Naidoo, Jacinth
Description: The kinetics of the pressure dependent O + SO2 + Ar reaction have been investigated using laser photolysis resonance fluorescence at temperatures of 289 K, 399 K, 581 K, 699 K, 842 K and 1040 K and at pressures from 30-665 torr. Falloff was observed for the first time in the pressure dependence. Application of Lindemann theory yielded an Arrhenius expression of k(T) = 3.3 x 10-32exp(-992/T) cm6 molecule-1 s-1 for the low pressure limit and k(T) = 8.47 x 10-14exp(-468/T) cm3 molecule-1 s-1 for the high pressure limit at temperatures between 289 and 842 K. The reaction is unusual as it possesses a positive activation energy at low temperature, yet at higher temperatures the activation energy is negative, illustrating a reaction barrier.
Contributing Partner: UNT Libraries
Interfacial Studies of Bimetallic Corrosion in Copper/Ruthenium Systems and Silicon Surface Modification with Organic and Organometallic Chemistry

Interfacial Studies of Bimetallic Corrosion in Copper/Ruthenium Systems and Silicon Surface Modification with Organic and Organometallic Chemistry

Access: Use of this item is restricted to the UNT Community.
Date: August 2006
Creator: Nalla, Praveen Reddy
Description: To form Cu interconnects, dual-damascene techniques like chemical mechanical planarization (CMP) and post-CMP became inevitable for removing the "overburden" Cu and for planarizing the wafer surface. During the CMP processing, Cu interconnects and barrier metal layers experience different electrochemical interactions depending on the slurry composition, pH, and ohmic contact with adjacent metal layers that would set corrosion process. Ruthenium as a replacement of existing diffusion barrier layer will require extensive investigation to eliminate or control the corrosion process during CMP and post CMP. Bimetallic corrosion process was investigated in the ammonium citrate (a complexing agent of Cu in CMP solutions) using micro test patterns and potentiodynamic measurements. The enhanced bimetallic corrosion of copper observed is due to noble behavior of the ruthenium metal. Cu formed Cu(II)-amine and Cu(II)-citrate complexes in alkaline and acidic solutions and a corrosion mechanism has been proposed. The currently used metallization process (PVD, CVD and ALD) require ultra-high vacuum and are expensive. A novel method of Si surface metallization process is discussed that can be achieved at room temperature and does not require ultra-high vacuum. Ruthenation of Si surface through strong Si-Ru covalent bond formation is demonstrated using different ruthenium carbonyl compounds. RBS analysis accounted for ...
Contributing Partner: UNT Libraries
Structural Elucidation of tert-Butyllithium/Lithium Alkoxide and Lithium Hydride/Lithium Alkoxide Mixed Aggregates

Structural Elucidation of tert-Butyllithium/Lithium Alkoxide and Lithium Hydride/Lithium Alkoxide Mixed Aggregates

Date: December 1997
Creator: Nguyen, Hanh D.
Description: The effects of lithium alkoxides on the rates of reactions and on the structures of a series of tert-butyllithium/lithium alkoxide mixed aggregates were studied, where the alkoxides were iso-butoxide, tert-butoxide and menthoxide. It was found that their effects depend not only on their amount present, but also on their steric bulk. The tert-butyllithium/lithium alkoxide mixed aggregates were exposed to UV light or heat to form lithium hydride/lithium alkoxide mixed aggregates. The aggregation states were assigned from either 13C-6Li coupling or a new technique based on the relative intensity of NMR peaks using different nuclei. The compounds formed depend upon the method of formation and the alkoxide. The unique properties of the lithium hydride/lithium alkoxide mixed aggregates are their high solubility in hydrocarbon solutions, very reactive bases, showing 6Li-1H couplings, and having only one hydride ion per aggregate. Their formation, reactivity, solubility, and aggregation states were found to depend on the size of lithium alkoxides. X-ray crystal structures of lithium tert-butoxide and lithium menthoxide were also studied and found to be hexameric.
Contributing Partner: UNT Libraries
Metal-Aluminum Oxide Interactions: Effects of Surface Hydroxylation and High Electric Field

Metal-Aluminum Oxide Interactions: Effects of Surface Hydroxylation and High Electric Field

Date: December 2001
Creator: Niu, Chengyu
Description: Metal and oxide interactions are of broad scientific and technological interest in areas such as heterogeneous catalysis, microelectronics, composite materials, and corrosion. In the real world, such interactions are often complicated by the presence of interfacial impurities and/or high electric fields that may change the thermodynamic and kinetic behaviors of the metal/oxide interfaces. This research includes: (1) the surface hydroxylation effects on the aluminum oxide interactions with copper adlayers, and (2) effects of high electric fields on the interface of thin aluminum oxide films and Ni3Al substrate. X-ray photoelectron spectroscopy (XPS) studies and first principles calculations have been carried out to compare copper adsorption on heavily hydroxylated a- Al2O3(0001) with dehydroxylated surfaces produced by Argon ion sputtering followed by annealing in oxygen. For a heavily hydroxylated surface with OH coverage of 0.47 monolayer (ML), sputter deposition of copper at 300 K results in a maximum Cu(I) coverage of ~0.35 ML, in agreement with theoretical predictions. Maximum Cu(I) coverage at 300 K decreases with decreasing surface hydroxylation. Exposure of a partially dehydroxylated a-Al2O3(0001) surface to either air or 2 Torr water vapor results in recovery of surface hydroxylation, which in turn increases the maximum Cu(I) coverage. The ability of surface hydroxyl ...
Contributing Partner: UNT Libraries
Synthesis and characterization of molecules to study the conformational barriers of fluorocarbon chains

Synthesis and characterization of molecules to study the conformational barriers of fluorocarbon chains

Date: May 2000
Creator: Niyogi, Sandip
Description: Fluorocarbons are known to be stiffer than their hydrocarbon analogues, a property that underlines the extensive industrial application of fluorocarbon materials. Although there has been previous studies on the rotational barrier of molecules having fluorocarbon centers, a detailed systematic study is necessary to quantify flurocarbon stiffness. The molecules, Pyrene-(CF2)n-Pyrene, Pyrene-(CF2)n-F, Pyrene-(CH2)n-Pyrene and Pyrene-(CH2)n-H were therefore synthesized to enable the determination of the barrier to rotation of the carbon backbone in fluorocarbons. Conformational studies will be completed with steady-state and time-dependent emission spectroscopy.
Contributing Partner: UNT Libraries
Surface and Interfacial Studies of Metal-Organic Chemical Vapor Deposition of Copper

Surface and Interfacial Studies of Metal-Organic Chemical Vapor Deposition of Copper

Date: December 1997
Creator: Nuesca, Guillermo M.
Description: The nucleation and successful growth of copper (Cu) thin films on diffusion barrier/adhesion promoter substrates during metal-organic chemical vapor deposition (MOCVD) are strongly dependent on the initial Cu precursor-substrate chemistry and surface conditions such as organic contamination and oxidation. This research focuses on the interactions of bis(1,1,1,5,5,5-hexafluoroacetylacetonato)copper(II), [Cu(hfac)2], with polycrystalline tantalum (Ta) and polycrystalline as well as epitaxial titanium nitride (TiN) substrates during Cu MOCVD, under ultra-high vacuum (UHV) conditions and low substrate temperatures (T < 500 K). The results obtained from X-ray photoelectron spectroscopy (XPS), Auger Electron Spectroscopy (AES) and Temperature Programmed Desorption (TPD) measurements indicate substantial differences in the chemical reaction pathways of metallic Cu formation from Cu(hfac)2 on TiN versus Ta surfaces.
Contributing Partner: UNT Libraries
Addition Reactions of Some Aromatic Aldazines

Addition Reactions of Some Aromatic Aldazines

Date: August 1954
Creator: O'Dell, Stewart
Description: The paper explores the conclusion that the addition compound was bicyclic, and that the addition of each of the two moles of cyanic acid was dependent upon the other.
Contributing Partner: UNT Libraries