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    Nonlinear optical studies of gypsum dissolution mechanisms, surfactant adsorption on gypsum surface and analysis of environmentally related ions
    (Montana State University - Bozeman, College of Letters & Science, 2023) Yiyen, Galip; Chairperson, Graduate Committee: Robert Walker; This is a manuscript style paper that includes co-authored chapters.
    Southeastern Montana hosts one of the largest open-air coal mine sites in the world. Federal regulations after finalization of the open-air coal mining activities require reclamation, which creates buried spoils that may serve as aquifers at former mining sites. Once hosting an inland sea, the region's saline sedimentary rocks and soils contribute to the groundwater salinity, though at lower levels prior to mining. However, the creation of spoils through mining pulverizes soils, sediment, and rocks formerly overlying coal deposits, mixing them and increasing their surface area. In infiltrating waters from snow melt and heavy rain, minerals dissolve more readily due to this enhanced surface area in spoils, increasing the salinity in groundwater. A primary water quality concern in regional groundwater is high sulfate concentrations. Sulfate in water originates from weathering and dissolution of soluble secondary salts, such as calcium sulfate (dihydrate, hemihydrate and anhydrite), sodium sulfate and magnesium sulfate. Gypsum (CaSO 4 x 2H 2O) is thought to be a primary source of dissolved sulfate in the ground and surface waters in Southeastern Montana and 'gypsum dissolution' is at the focus of this dissertation. Vibrational sum frequency generation spectroscopy was used to understand the molecular level interactions at the gypsum surface upon interaction with bulk water. Additionally, surfactant adsorption on gypsum surface and its impacts of gypsum dissolution were investigated. Besides optical spectroscopy studies, an efficient and quick water analysis technique was adapted to determine the sulfate concentrations in environmental samples. Two different types of orientations of structural water molecules at the gypsum surface were observed. Results also showed that these water molecules are tightly bound to the surface. Surfactant adsorption was found to be only limited to the surfactants with sulfate headgroups and resulted in suppressed gypsum dissolution. A titration technique is found to be effective and accurate for sulfate analysis of environmental water samples.
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    Organic enrichment at aqueous interfaces studied with non-linear spectroscopy: cooperative adsorption of soluble saccharides to lipid monolayers
    (Montana State University - Bozeman, College of Letters & Science, 2019) Link, Katie Ann; Chairperson, Graduate Committee: Robert Walker; Chia-Yun Hsieh, Aashish Tuladhar, Zizwe Chase, Zheming Wang, Hongfei Wang and Robert A. Walker were co-authors of the article, 'Vibrational studies of saccharide-induced lipid film reorganization at aqueous/vapor interfaces' in the journal 'Chemical physics' which is contained within this thesis.; Gabrielle N. Spurzem, Aashish Tuladhar, Zizwe Chase, Zheming Wang, Hongfei Wang and Robert A. Walker were co-authors of the article, 'Organic enrichment at aqueous interfaces: cooperative adsorption of glucuronic acid to DPPC monolayers studied with vibrational sum frequency generation' submitted to the journal 'Journal of physical chemistry B' which is contained within this thesis.; Gabrielle N. Spurzem, Aashish Tuladhar, Zizwe Chase, Zheming Wang, Hongfei Wang, and Robert A. Walker were co-authors of the article, 'Cooperative adsorption of trehalose to DPPC studied with vibrational sum frequency generation' which is contained within this thesis.
    Field measurements of sea spray aerosols have reported high concentrations of soluble organic material that are in excess of the concentration of soluble organics in the ocean. The studies described in this dissertation investigated a possible mechanism for this increase deemed cooperative adsorption. The cooperative adsorption mechanism describes an interaction between an insoluble Langmuir monolayer at the aqueous/vapor interface and soluble organic molecules that would not normally be enriched at the surface. In this model, the soluble organics are drawn to the surface through non-covalent interactions with the lipid surfactant. This mechanism was investigated with the surface specific nonlinear optical technique, vibrational sum frequency generation spectroscopy. These optical measurements were coupled with surface tension measurements and differential scanning calorimetry measurements. To study cooperative adsorption, model systems were used; these were composed of a phosphatidylcholine lipid surfactant, DPPC, and soluble saccharides including glucosamine, glucuronic acid, and trehalose. Glucosamine, in both a positive and neutral state, induced ordering in both expanded and condensed DPPC monolayers, supporting cooperative adsorption as a mechanism. Glucuronic acid, an anion, ordered lipid monolayers in the limits that the lipid DPPC was moderately packed and there were no competing ions in solution. Trehalose, a larger, uncharged saccharide showed, through ordering the DPPC monolayer, indications of cooperative adsorption in moderately packed DPPC when the trehalose concentration was sufficiently high. These results support cooperative adsorption as a mechanism for the accumulation of soluble organics in sea spray aerosols with some limitations.
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    Diethyl zinc mediated intramolecular metalloamination of N,N-dimethylhydrazines: expanding a novel approach to functionalized pyrrolidines and piperidines. Utilizing synthesis as a tool for medicinal chemistry, environmental remediation, and nonlinear optical chromophore construction
    (Montana State University - Bozeman, College of Letters & Science, 2017) Mickelsen, Ky James; Chairperson, Graduate Committee: Thomas S. Livinghouse; Dissertation contains an article of which Ky James Mickelsen is not the main author.; Sean Zabawa and Tom Livinghouse were co-authors of the article, 'Diethylzinc mediated metalloamination-alkylation of N,N-dimethylhydrazinoalkenes. Catalysis of carbon-zinc alkylation using simple copper(I) salts' in the journal 'Synlett' which is contained within this thesis.
    When attempting to develop a novel material for increased second-order nonlinear activity, a strategy was devised to rationally design an architecture that would allow for optimized acentric supramolecular organization. By coupling a liquid crystal tolane to a well-understood NLO chromophore via strategic synthesis, a set of novel chromophores was created. The ferroelectric liquid crystal-like molecules intrinsically favor unidirectional chromophore order while simultaneously containing a high beta chromophore along the polar axis. This system has shown potential for high terminal stability as well as increased nonlinear optical susceptibilities. Carbon tetrachloride poses a large threat to the environment and is the focus of ongoing remediation efforts. It is a well-known carcinogenic pollutant that has contaminated groundwater beneath former grain storage and industrial sites, such as the Department of Energy's Hanford site. Remediation through the use of a small molecule, PDTC, when complexed with copper has been shown to lead to complete dechlorination, resulting in conversion to non-toxic end-products (mostly CO 2) and complete removal of the problematic carbon-chlorine bonds. Synthetic chemistry was employed to develop a modified procedure for large-scale production of PDTC that eliminates harmful byproducts and excess toxic reagents used. Additionally, structural derivatives for increased water solubility have been envisaged from citrazinic acid, which could allow for aqueous destruction of carbon tetrachloride. In medicinal and pharmaceutical chemistry, routes to nitrogenous heterocycles are of great importance due to their prevalence in bioactive molecules. Diethylzinc mediated metalloamination/cyclization of unsaturated N,N-dimethylhydrazines with subsequent electrophilic functionalization could prove to be a powerful tool for constructing pyrrolidines and piperidines. This method was extended to the use of 1,2-disubstituted alkenes as N-Zn migratory insertion acceptors, including various vinylcyclopropyl hydrazines. The potential behind the irreversible cyclopropane scission and development of a new alkene make this class of substrates extremely desirable. The metalloamination-alkylation of N,N-dimethylhydrazinoalkenes was shown to be effectively catalyzed by CuBr x SMe 2, CuCN and CuI. This novel method obviates the prior methodology involving use of stoichiometric CuCN(LiCl) 2 as a promoter for the electrophilic functionalization.
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    Photonic applications of functionalized gold nanorods: progress towards nonlinear metamaterials
    (Montana State University - Bozeman, College of Letters & Science, 2016) Latterman, Ryan Eric Michael; Chairperson, Graduate Committee: Robert Walker; This dissertation contains one article of which Ryan Eric Michael Latterman is not the main author.
    Nonlinear processes are used to convert one color of laser light into another and are very useful to any research who needs multiple colors of light for basic research or commercial purposes. However, nonlinear processes are inherently very weak and require high input energy to utilize them. Using modeling, it was predicted that ordered arrays of gold nanorods (GNRs), acting as a metamaterial, could be used to fabricate a material that would exhibit field enhancement. Because nonlinear processes depend on the strength of the field in which they interact, enhancing the field strength while using the same amount of input power would make these processes much more efficient and useful. Progress towards these materials included the synthesis of GNRs and gold reactive polymers. These polymers were used to solubilize GNRs in organic solvents while also introducing attachment points for nonlinear chromophores. To study a material which resembled the one in our modeling predictions, flat gold and two dimensional arrays of gold nanopillars were functionalized with gold-reactive nonlinear organic chromophores and studied using sum frequency generation. It was found that flat gold samples functionalized with a nonlinear chromophore exhibited a tremendous SFG signal, but only in one input polarization configuration. However, gold nanopillar samples exhibited a significant SFG signal in both PPP and SSP polarization configurations. These data agree with our modeling results and indicate that the materials produced here have the potential to be used as a mirror-less optical parametric oscillator. Organic-soluble GNRs produced in this thesis were then used in an adjacent project to improve the efficiency of a diode-pumped solid state laser design. Nd:YAG lasers are routinely used to produced 1064 nm light by pumping at 808 nm with a semi-conductor diode laser. However, when 1064 nm light is reflected back into the laser cavity, a parasitic phenomenon called amplified spontaneous emission (ASE) occurs. ASE can be combatted by applying a material to the laser rod that absorbs at 1064 nm. GNRs were synthesized at a specific size to absorb at 1064 nm, solubilized in epoxy and applied to a Nd:YAG laser, increasing efficiency by almost two fold.
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    Design and synthesis of new nonlinear optical chromophores incorporating diphenylphosphino groups and their incorporation into electroactive dendrimers
    (Montana State University - Bozeman, College of Letters & Science, 2000) Madrigal, Luis Gustavo
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    The synthesis and characterization of organic materials for non-linear optic studies
    (Montana State University - Bozeman, College of Letters & Science, 1996) Duncan, David F.
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    Synthesis and charge state formation in dendrons and dendrimers incorporating dithienylpolyene moieties
    (Montana State University - Bozeman, College of Letters & Science, 2000) Ozer, Berrak
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