Theses and Dissertations at Montana State University (MSU)
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Item Study of MRK 110 using x-ray spectroscopy(Montana State University - Bozeman, College of Letters & Science, 2019) Liang, Xiao (Jennifer); Chairperson, Graduate Committee: Anne LohfinkJets are one of the most mysterious, and fascinating subjects in the study of relativistic outflow of the high energy particles produced by the Active Galactic Nuclei (AGN). AGNs are the center of active galaxies, where a very massive black hole is actively accreting matter into it. The relationship between the black hole mass and the luminosity is produced through accretion is known as the fundamental plane of black hole activities. The goal is to probe the characteristics of the black hole and its close vicinity by studying the X-ray produced by this inner region. We report the finding of high energy X-ray photons of a low radio luminous galaxy Mrk 110 from NuSTAR observations. We've found there are almost no variations in the X-ray flux during time scale observation, and there is a linear correlation between 3-5 keV and 5-10 keV energy band. We also find that the energy spectrum is best modeled by a cutoff power law and a red-shifted Gaussian modeling the fluorescence emission. Fluorescence emission is one of the signatures when X-rays are reflected by the disk. However the other significant reflection component, --X-rays signals reflected by the disk, is missing. We suspect the cause of the unexpected amount of high energy X-ray flux is due to jet emissions.Item Multi-edge X-ray absorption near-edge spectroscopic analysis of palladium complexes in II, III and IV oxidation states(Montana State University - Bozeman, College of Letters & Science, 2013) Barton, Rhonda Lee Hoffert; Chairperson, Graduate Committee: Robert K. SzilagyiPalladium-based complexes have profoundly impact on the synthetic tools of organic chemists due to their importance as catalysts in a myriad of chemical transformations. Palladium in the 0, II, III and IV oxidation states have all been experimentally observed to have catalytic activity in carbon-carbon bond coupling reactions. A common organometallic research aim is to improve catalytic activity of these complexes by designing and optimizing new ligand systems to access more difficult transformations. In order to understand the electronic effects that ligand systems have on reactivity, X-ray absorption spectroscopy is used to characterize the electronic structure of the ligand and metal components of pre-catalysts and palladium model complexes. The multi-edge X-ray absorption near-edge absorption spectroscopic technique (XANES) is an element specific technique that excites core electrons of the 1s (K-edge) and 2p (L-edge) orbitals to frontier unoccupied molecular orbitals, providing a ground state picture of a complex's ligand and metal electronic structure. This thisis will describe a comparative analysis between homoleptic chloropalladium complexes and interesting heteroleptic palladium based complexes of II, III and IV oxidation states to understand the stabilizing effects of a unique ligand environment. Furthermore, it will emphasize the benefits of using multi-edge XANES technique in rationalized catalyst design.Item Depth profiling using XPS(Montana State University - Bozeman, College of Engineering, 2000) Hunt, Stephen MichaelItem Development of the molecular level descripton for nickel(II)-based ligand-exchange thermochromism(Montana State University - Bozeman, College of Letters & Science, 2014) Queen, Matthew Scott; Co-chairpersons, Graduate Committee: Patrick R. Callis and Robert K. Szilagyi; Bradley D. Towey, Kevin A. Murray, Brad S. Veldkamp, Harlan J. Byker and Robert K. Szilagyi were co-authors of the article, 'Electronic structure of [Ni(II)S 4] complexes from S K-edge X-ray absorption spectroscopy' in the journal 'Coordination chemistry reviews' which is contained within this thesis.; Farideh Jalilehvand and Robert K. Szilagyi were co-authors of the article, 'Electronic structure of Ni(II), Co(II), and Zn(II) thiourea complexes from sulfur K-edge X-ray absorption spectroscopy' submitted to the journal 'Canadian journal of chemistry' which is contained within this thesis.Coordination compound-based nickel(II) thermochromic systems rely on a temperature-dependent equilibrium shift between different coordination environments of the central nickel ion. These systems are found in thermochromic "smart windows" that tint reversibly in response to temperature increases in their environment providing the benefit of energy savings in commercial and private buildings. Despite the stoichiometrically simple equilibrium for these ligand exchange systems, there is a complex and delicate network of chemical interactions that determine the color, and thermodynamic performance. Accurate computational modeling of nickel(II) ligand exchange thermochromic systems is an important first step in the direction of understanding the parameter space that determines whether a given metal ligand system is thermochromic, the color of the high and low temperature species, the temperature at which the system will change color. The research presented in this dissertation uses experimental results to evaluate theoretical models. Core and valence electronic spectroscopies probe the ground and excited state electronic structures of high temperature nickel(II) thermochromic chromophores which range from the very covalent nickel tetrathiocyclotetradecane thiocrownether to the highly ionic nickel dibromodi(1-pentylbenzimidazole)nickel(II). The experimental electronic structures of these high temperature species combined with experimental ligand exchange thermodynamics are used to guide the evaluation of computational modeling methods in search of methods that reproduces the experimental observables. It is found that commercially relevant nickel(II) thermochromism takes place on an extremely flat potential energy surface governed by ion pairing, hydrogen bonding and dispersion interactions. The modeling of these surfaces requires the explicit consideration of ion pairing and solvent-solute interactions.Item Epitaxial thin film deposition of magnetostrictive materials and its effect on magnetic anisotropy(Montana State University - Bozeman, College of Letters & Science, 2012) McClure, Adam Marc; Chairperson, Graduate Committee: Yves U. Idzerda; Steven Albert, Tino Jaeger, Hongyan Li, Paul Rugheimer, Juergen A. Schaefer and Yves U. Idzerda were co-authors of the article, 'Properties of single crystal Fe 1-xGa x thin films' in the journal 'Journal of applied physics' which is contained within this thesis.; Elke Arenholz and Yves U. Idzerda were co-authors of the article, 'Ferrimagnetic ordering of single crystal Fe 1-xGa x thin films' in the journal 'Journal of vacuum science and technology A' which is contained within this thesis.; Hongyan Li and Yves U. Idzerda were co-authors of the article, 'Magnetostrictive effect in single crystal Fe 1-xGa x thin films' in the journal 'Journal of applied physics' which is contained within this thesis.; Paul Rugheimer and Yves U. Idzerda were co-authors of the article, 'Magnetic and structural properties of single crystal Fe 1-xZn x thin films' in the journal 'Journal of applied physics' which is contained within this thesis.Magnetostriction means that the dimensions of a material depend on its magnetization. The primary goal of this dissertation was to understand the effect of magnetostriction on the magnetic anisotropy of single crystal magnetostrictive thin films, where the epitaxial pinning of the material to a substrate could inhibit its conversion to new dimensions. In order to address this goal, several Fe-based binary alloys were deposited onto various substrates by molecular beam epitaxy. The samples were characterized by an array of techniques including electron diffraction, Rutherford backscattering, vibrating sample magnetometry, ferromagnetic resonance, and x-ray absorption spectroscopies. The attempted growths of crystalline magnetostrictive thin films resulted in successful depositions of Fe 1-xGa x and Fe 1-xZn x. Depositions onto MgO(001) substrates result in an in-plane cubic magnetic anisotropy, as expected from the cubic symmetry of the Fe-based thin films, and a strong out-of-plane uniaxial anisotropy that forces the magnetization to lie in the plane of the films. Depositions onto ZnSe/GaAs(001) substrates feature an additional in-plane uniaxial anisotropy. The magnitudes and signs of the in-plane anisotropies depend on the Ga content. Furthermore, the cubic anisotropy constant of Fe 1-xGa x samples deposited onto MgO substrates switches sign at a lower Ga concentration than is seen in bulk Fe 1-xGa x. The effect on the magnetic anisotropy of depositing a magnetostrictive material as an epitaxial thin film is influenced by the material's magnetostrictive properties and the substrate upon which it is deposited. In particular, pinning a magnetoelastic material to a substrate will modify its cubic anisotropy, and depositions on substrates compliant to an anisotropic strain relaxation may result in a strong in-plane uniaxial anisotropy.