Physical Sciences and Mathematics Commons^™

Quantitative Analysis Of Acetylsalicylic Acid By Q-Nmr (Quantitative-Nuclear Magnetic Resonance Spectroscopy), Charles Flemming Jr.

All Student Theses

Quantitative analysis is an important step during pharmaceutical drug development. Currently, the pharmaceutical industry uses high performance liquid chromatography (HPLC) for quantitative analysis of organic compounds as the preferred technique. The proton nuclear magnetic resonance (NMR) technique has an inherent ability to quantify a given analyte and may be used to quantify organic compounds. Quantitative nuclear magnetic resonance spectroscopy (q-NMR) of acetylsalicylic acid (ASA) was conducted using tert-butyl alcohol (tert-butanol) as the internal standard and deuterated chloroform (CDCl₃) as the solvent. Preparations of ASA solutions in low and high concentration ranges, 1.0 mM – 10.1 …

Ultraviolet And Infrared Spectroscopy Of Synthetic Foldamers, Aib Homopeptides, And Solvated 1,2-Diphenylethane In The Gas Phase, Joseph R. Gord

Open Access Dissertations

The work presented here implements a supersonic jet expansion source to funnel the population of model peptides and solvated-bichromophore clusters into their low lying structural minima and to collisionally cool these minima to their respective zero-point vibrational levels. Single-conformation ultraviolet and infrared spectroscopy techniques are then used to probe these systems and investigate their electronic properties and uncover their intrinsic conformational preferences in the gas phase.

Model β/γ-peptides known as synthetic foldamers and aminoisobutyric acid (Aib) homopeptides incorporate structural constraints that are designed/known to impose particular structural motifs. Here the ability of a β/γ-dipeptide to replicate the backbone length of …

Single-Conformation Spectroscopy Of Hydrogen Bonding Networks: Solvation, Synthetic Foldamers, And Neurodegenerative Diseases, Patrick S. Walsh

Open Access Dissertations

The hydrogen bond is one of the most important interactions in natural processes ranging from protein folding to chemical reactions. Two complementary methodologies are applied to understanding this important interaction: top-down and bottom-up. Top-down methods use large molecules, such as proteins, revealing secondary structure information. Bottom-up experiments are performed on small molecules, utilizing high-resolution spectroscopy to reveal underlying quantum mechanical effects. The complexity gap is formed between these two experimental regimes; between large and small molecules; between bulk and individual solvent molecules; between classical mechanics calculations and quantum chemical calculations. This dissertation will focus on the application of gas phase, …

Novel Pathways To High-Efficiency Chalcopyrite Photovoltaic Devices: A Spectroscopic Investigation Of Alternative Buffer Layers And Alkali-Treated Absorbers, Michelle Mezher

UNLV Theses, Dissertations, Professional Papers, and Capstones

Within the past few years, breakthroughs in Cu(In,Ga)Se₂ (CIGSe) thin-film photovoltaic device efficiencies (on a laboratory scale) were achieved utilizing alkali-treated (KF) absorbers. Na incorporation in the CIGSe absorber, either diffused from the substrate or deliberately deposited, affects the surface electronic properties of the CIGSe absorber. The role of Na, however, is still not fully understood with some studies suggesting that Na also passivates defects at the grain boundaries. Replacing Na with K offered an efficiency boost resulting in KF treatments becoming the new “hot topic” in the chalcopyrite field, both in terms of understanding how the treatment changes …

Mining Uranium From Seawater: A Coordination Chemistry Approach, Nada Mehio

Doctoral Dissertations

Poly(acrylamidoxime) fibers are the current state-of-the-art adsorbent for mining uranium from seawater. However, the amidoxime group is not perfectly selective towards the uranyl cation, in particular, competition with transition metal cations remains a major challenge. In order for subsequent generations of chelating polymer adsorbents to be improved, the coordination chemistry of amidoxime-uranyl and -transition metal cation complexes needs to be better understood. While the coordination mode of amidoxime-uranyl complexes has been established in the literature, a number of amidoxime-transition metal cation complex binding motifs can be observed on the Cambridge Structrural Database. Likewise, the formation constants, or log K values, …

Development Of Novel Analytical Methods With The Aim Of Forensic Analyte Detection Using Ultra-Thin Layer Chromatography, Surface Enhanced Raman Spectroscopy, And Magneto-Elastic Wire Sensing, Nichole Ann Crane

Doctoral Dissertations

The purpose of this dissertation is to develop analytical methods that aid in the detection of forensic analytes. Forensic analytes require methods with increased sensitivity and low limit of detection capabilities. Improvements in separation techniques, surface enhanced Raman spectroscopic techniques, and wire-less gas sensing can each assist in the detection of trace evidence.

When surface enhanced Raman is coupled with thin-layer chromatography a mixture of compounds can be separated and transferred to a metal substrate to be detected using Raman spectroscopy. Surface enhanced Raman scattering enhances the Raman signal intensity by placing a metal substrate in close proximity to an …

Vespucci: A Free, Cross-Platform Software Tool For Spectroscopic Data Analysis And Imaging, Daniel Patrick Foose

Browse all Theses and Dissertations

Vespucci is a software application developed for imaging and analysis of hyperspectral datasets. Vespucci offers several advantages over other software packages, including a simple user interface, no cost, and less restrictive licensing. Vespucci incorporates several analysis techniques including univariate imaging, principal components analysis, partial-least-squares regression, vertex components analysis and k- means clustering. Additionally, Vespucci can perform a number of useful data-processing operations, including filtering, normalization, baseline correction, and background subtraction. Datasets that consist of spatial or temporal data with a corresponding digital signal, including spectroscopic images, mass spectrometric images, and X-ray diffraction data can be processed in this software. The …

3d Printing Applications Within Spectrophotometry, Eric J. Stanczyk

Williams Honors College, Honors Research Projects

Ultraviolet-visible spectroscopy is a tool used throughout the field of chemistry and in chemical labs across the world. Spectrophotometers are a core technology in analytical chemistry, and are used to obtain accurate data on solution concentration. Unfortunately spectrophotometers can be difficult to obtain due to their high cost and low availability outside of a laboratory; this is especially true in either high school or lower grades where buying a spectrophotometer could be considered unreasonable due to price. There are ways to obtain cheaper spectrophotometers, but they can have a high initial cost or low overall quality. This paper will discuss …

Issues In Laser Induced Breakdown Spectroscopy For Measurements In The Deep Ocean And Other High-Pressure Environments, Joseph C. Bonvallet

Theses and Dissertations

This dissertation describes fundamental and applied studies that have advanced the understanding and application laser induced breakdown spectroscopy (LIBS) to the deep-ocean environment and to operation on a deep-ocean submersible. Chapter one is an overview of LIBS including a brief history, LIBS theory, the instrumentation typically used, and a specific application. Chapter two analyzes the effect that monodisperse suspended particles have on LIBS emission intensity and on the formation of a LIBS plasma. This chapter demonstrates that for particle concentrations similar to those found in the neutrally buoyant regions around hydrothermal vents there is little effect on the LIBS emission …

Excitonic States In Crystalline Organic Semiconductors: A Condensed Matter Approach, Lane Wright Manning

Graduate College Dissertations and Theses

In this work, a new condensed matter approach to the study of excitons based on crystalline thin films of the organic molecule phthalocyanine is introduced. The premise is inspired by a wealth of studies in inorganic semiconductor ternary alloys (such as AlGaN, InGaN, SiGe) where tuning compositional disorder can result in exciton localization by alloy potential fluctuations. Comprehensive absorption, luminescence, linear dichroism and electron radiative lifetime studies were performed on both pure and alloy samples of metal-free octabutoxy-phthalocyanine and transition metal octabutoxy-phthalocyanines, where the metal is Mn, Co, Ni, and Cu. Varying the ratios of the metal to metal-free phthalocyanines …