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Developing Carbon Quantum Dots As A Luminescent Material And Revisiting Ecl And Led Absolute Measurement Methods, Jonathan Ralph Adsetts

Electronic Thesis and Dissertation Repository

Luminescent materials play increasingly important roles in our lives. Improvements in these materials’ quantum efficiencies (QEs), costs and toxicity can greatly reduce the power consumption, price and environmental damage to the planet, respectively. Carbon quantum dots (CQDs) and luminescent materials exhibiting thermally activated delayed fluorescence (TADF) are two interesting materials in these aspects. Furthermore, measurements on electrochemiluminescence (ECL) and electroluminescence of these luminescent materials can quickly evaluate their performance for many applications. In this thesis, controlled CQD syntheses are revealed beneficial to luminescent materials applications. Their film ECL demonstrated relatively stable anionic and cationic radicals leading to high emission at …

Engineering Rare-Earth Based Color Centers In Wide Bandgap Semiconductors For Quantum And Nanoscale Applications, Gabriel I. López-Morales

Dissertations, Theses, and Capstone Projects

For many years, atomic point-defects have been readily used to tune the bulk properties of solid-state crystalline materials, for instance, through the inclusion of elemental impurities (doping) during growth, or post-processing treatments such as ion bombardment or high-energy irradiation. Such atomic point-defects introduce local ‘incompatible’ chemical interactions with the periodic atomic arrangement that makes up the crystal, resulting for example in localized electronic states due to dangling bonds or excess of electrons. When present in sufficient concentrations, the defects interact collectively to alter the overall bulk properties of the host material. In the low concentration limit, however, point-defects can serve …

Control Of Nonlinear Properties Of Van Der Waals Materials, Rezlind Bushati

Dissertations, Theses, and Capstone Projects

Van der Waals materials are a broad class of materials that exhibit unique optoelectronic properties. They provide a rich playground for which they can be integrated into current on-chip devices due to their nanometer-scale size, and be utilized for studying fundamental physics. Strong coupling of emitters to microcavities provides many opportunities for new exotic physics through the formation of hybrid quasi-particles exciton-polaritons. This thesis
focuses on exploring and enhancing nonlinearity of van der Waals materials through strongly coupling to microcavities. By taking advantage of the stacking order of TMDs, we show intense second-harmonic generation from bulk, centrosymmetric TMD systems. In …

Driving Piezochromism And Metallicity In Van Der Waals Materials Under Compression, Nathan Harms

Doctoral Dissertations

Complex chalcogenides provide an important platform to explore the interplay between structure, charge, and spin across pressure-induced phase transitions. Where much of the previous research has been focused on tuning these materials towards the single-layer limit, we instead explore the modification of bond lengths and bond angles under compression. In the first project we revealed piezochromism in MnPS₃. We combined high pressure optical spectroscopy and first-principles calculations to analyze the dramatic color change (green → yellow → red → black) that takes place as the charge gap shifts across the visible and into the near infrared region, moving …

Design And Fabrication Of An Apparatus For Tao High-Resolution Laser Spectroscopy, Timothy Chung

UNLV Theses, Dissertations, Professional Papers, and Capstones

In this study, an apparatus for the high-resolution laser spectroscopy of molecules is designed and constructed. The apparatus is used to identify TaO transitions, but may be used for any other molecular species in the future. It will also later be used for experiments such as quantum logic spectroscopy, which are enabled by attachable chambers that can be supplied with molecules from the apparatus. Several considerations are made to improve the quality and longevity of the apparatus such as regulating the rovibrational states of the produced molecules, optimizing the linewidth of the ionization lasers, reducing noise from sources such as …

Nondestructive Evaluation Of 3d Printed, Extruded, And Natural Polymer Structures Using Terahertz Spectroscopy And Imaging, Alexander T. Clark

Dissertations

Terahertz (THz) spectroscopy and imaging are considered for the nondestructive evaluation (NDE) of various three-dimensional (3D) printed, extruded, and natural polymer structures. THz radiation is the prime candidate for many NDE challenges due to the added benefits of safety, increased contrast and depth resolution, and optical characteristic visualization when compared to other techniques. THz imaging, using a wide bandwidth pulse-based system, can evaluate the external and internal structure of most nonconductive and nonpolar materials without any permanent effects. NDE images can be created based on THz pulse attributes or a material’s spectroscopic characteristics such as refractive index, attenuation coefficient, or …

Monitoring Bacteria Cultures Using Near Infrared (Nir) Binary Spectronephelometry (Bsn), Raman Spectra And Principal Component Analysis (Pca), Steven Ortiz

Dissertations - ALL

Current noninvasive methods cannot continuously and simultaneously monitor the concentrations of cells and media components that define the state of native bacterial cultures, because of changing turbidity. A new technique, binary spectronephelometry (BSN) has the same or better sensitivity and precision for population monitoring as optical density at 600nm (OD600), while simultaneously measuring metabolic processes. The BSN algorithm uses laser induced emission to probe mildly turbid media i.e., propagation of light occurs in the single scattering regime. A BSN "training set" associates a grid of elastic emission measurements, comprising Rayleigh and Mie scattering, and inelastic emission measurements, comprising fluorescence and …

The Exploration Of Small Molecules, Lanthanide Complexes, And Catalysis Using Electronic Structure Theory, Dynamics, And Machine Learning, Gavin Mccarver

Doctoral Dissertations

With the ever increasing availability of computational resources, more challenging chemical systems can be studied. Among these challenges are the rotational and vibrational spectra of diatomic molecules within spectroscopic accuracy, the environmental perturbations induced on a rotating water molecule, the prediction of free binding energies of lanthanide complexes using machine learning, and the study of catalytic mechanisms through a theoretical framework. High levels of electronic structure theory were combined with a rigorous treatment of either the anharmonic vibrational wave functions to study diatomic molecules or the rotational wave functions to study H₂O-pH₂ interactions. The former was initially …

Experimental Investigation Of All-Optical Production Of Metastable Krypton, Joshua Carl Frechem

Physics Theses & Dissertations

Metastable production of noble gases requires significant energy due to their filled valence shells. These transitions from the ground state are in the vacuum ultraviolet and extreme ultraviolet, which are relatively inaccessible to lasers. This necessitates the use of either electron/ion bombardment via inefficient glow discharges or the use of high-power lasers and nonlinear processes. The all-optical production efficiency using these high-power lasers promises to be orders of magnitude higher than glow discharges, but far more costly. This work looks to improve all-optical production of metastable krypton (Kr*) through the use of a commercially available vacuum ultraviolet lamp with a …

Hierarchical Modelling Of Raman Spectroscopic Data Demonstrates The Potential For Manufacturer And Caliber Differentiation Of Smokeless Powders, Nathan Russell Bartlett

Legacy Theses & Dissertations (2009 - 2024)

With the rise of gun-based crime and the advent of lead-free ammunition reducing the effectiveness of previously used methods, the analysis of smokeless powders to better understand organic gunshot residues is now more important than ever. One method that has shown potential is Raman spectroscopy, a relatively quick, nondestructive, and non-contact analysis method. To investigate whether Raman spectroscopy could be used to characterize individual powders, samples of smokeless powders from three manufacturers, Remington, Federal, and Winchester, each with two 9mm caliber and two .38 caliber ammo types, were dissolved, and their Raman spectra were collected. A hierarchical modelling system was …

Supertertiary Structural Dynamics Modulate Function In Postsynaptic Density Protein 95, George L. Hamilton Iii

All Dissertations

Proteins, RNA, and DNA serve as the primary sub-cellular machinery that give rise to the necessary functions of life. The long-standing paradigm has been that the structures of biomolecules, or the arrangement of the subunits that make up a biomolecule, determine biological function. However, biomolecules are not static objects. Instead, they often undergo structural rearrangements that are crucial to enabling and regulating their functions. In my thesis I present several studies of the interplay between the structures, dynamics, and functions of biomolecules that combine experimental fluorescence spectroscopy and computational methods to probe these systems at the single-molecule level. In particular, …

Spectroscopic Measurements Of Meibum Compositional, Structural, And Functional Relationships To Elucidate The Role Of Meibum In Dry Eye., Anthony Chigozie Ewurum

Electronic Theses and Dissertations

The major aim of my dissertation was to investigate the etiology of dry eye disease which affects about 7 million people in the United States, causing symptoms that can lead to visual disturbance. Correlation between dry eye and an abnormal lipid layer of the tear film has been found. Tear film lipids originate mostly from the meibomian glands. Cholesteryl ester (CE) and Wax ester (WE) lipids make up most of the human meibum lipidome and the CE/WE ratio has been shown to decrease in patients with meibomian gland dysfunction. Model studies using synthetic CE and WE, although providing some insight, …

Enigma - Ongoing Development Towards Novel Beta-Decay Spectroscopy Station At Isolde, Philipp Wagenknecht

Masters Theses

Beta decay and collinear laser spectroscopy are proven efficient tools to study nuclear structure far from stability. Two areas of significance are investigations into nuclear deformation and shape coexistence, as well as delayed neutron emissions used in nuclear energy applications. This contribution presents the ongoing development towards a novel beta-decay spectroscopy station for the VITO experiment at CERN’s radioactive ion beam facility ISOLDE. The setup will utilize both collinear laser spectroscopy and beta-decay spectroscopy to measure the energy and spin-parities of the ground and excited states of radioactive beams. Initial designs of the support structure, magnetic field, and detector array …

Approaches In Molecular Engineering To Optimize The Desired Properties Of Photoactive Molecules, Douglas Joseph Breen

Chemistry and Chemical Biology ETDs

Within this dissertation, photochemical systems that bear significance to next-generation photonic materials and devices are explored. Notable advances in the design, synthesis, and characterization of three distinct groups of photoactive molecules are achieved through molecular design and spectroscopic analysis. First, novel ruthenium sulfoxide complexes bearing substituted phosphine ligands are found to provide extraordinary control over photoisomerization quantum yields. A comparison of these complexes reveals ground-state characteristics that are instrumental in this reactivity, while a novel spectroscopic technique provides rare structural evidence for an O-bonded metastable isomer. Ruthenium complexes bearing chelating carbene-sulfoxide ligands rapidly thermally revert from the O-bonded metastable isomer …

Infrared Investigation Of Lithium Ion Electrolytes: Characterization Of Structure And Dynamics Via Linear And Nonlinear Spectroscopy, Jeramie Christopher Rushing

LSU Doctoral Dissertations

Lithium ion batteries are widely employed in energy storage, but the connection between the molecular interactions in their electrolytes and the macroscopic properties remains elusive. Across three vastly different electrolytes, speciation and dynamics were studied via linear and nonlinear infrared spectroscopy to shed light on this relationship. The impact of mixed solvation on ionic speciation was studied from the perspective of the anion, which revealed a significant energetic favorability for the formation of contact ion pairs in linear carbonate solvents over cyclic carbonates. Infrared spectroscopy and density functional theory calculations described a complete inversion of the speciation due to solvent …

Electron Spin Relaxation Of Nitroxide Spin Labels And Relaxation Processes, Thacien Ngendahimana

Electronic Theses and Dissertations

MTSL is the nitroxide spin label that is most commonly used in site-directed spin labeling. However, due to rotation of its gem-dimethyl groups that average anisotropic interactions, T_m becomes short above about 70 K and this makes DEER experiments difficult at these temperatures. Strategies for decreasing spin echo dephasing and electron spin lattice relaxation rates are important for design of nitroxide spin labels and molecular qubits.

In searching for labels with longer T_m, new nitroxide spin labels devoid of gemdimethyl groups or with more rigid structures were synthesized at the University of Nebraska and pulsed EPR measurements …

Charge Dynamics Of Inas Quantum Dots Under Resonant And Above-Band Excitation, Gary R. Lander Jr

Graduate Theses, Dissertations, and Problem Reports

Research involving light-matter interactions in semiconductor nanostructures has been an interesting topic of investigation for decades. Many systems have been studied for not only probing fundamental physics of the solid state, but also for direct development of technological advancements. Research regarding self-assembled, epitaxially grown quantum dots (QDs) has proven to be prominent in both regards. The development of a reliable, robust source for the production of quantum bits to be utilized in quantum information protocols is a leading venture in the world of condensed matter and solid-state physics. Fluorescence from resonantly driven QDs is a promising candidate for the production …

Characterization And Coherent Spin Selective Manipulation Of Quantum Dot Energy Levels, Tristan Anthony Wilkinson

Graduate Theses, Dissertations, and Problem Reports

Semiconductor quantum dots (QDs) are promising candidates to fulfill a wide range of applications in real-world quantum computing, communication, and networks. Their excellent optical properties such as high brightness, single-photon purity, and narrow linewidths show potential utility in many areas. In order to realize long term goals of integration into complex and scalable quantum information systems, many current challenges must be overcome. One of these challenges is accomplishment of all necessary computing operations within a QD, which might be enabled by coherent manipulation of single QD energy level structures. In the realm of scalability for quantum devices, a way to …

A Mastcam Multispectral Investigation Of Rock Variability In Gale Crater, Mars: Implications For Alteration In The Clay-Sulfate Transition Of Mount Sharp, Alivia Eng

WWU Graduate School Collection

The Mars Science Laboratory Curiosity rover has explored over 650 m of strata since landing in 2012. After leaving Vera Rubin Ridge (VRR), the rover traversed though the phyllosilicate-rich region, Glen Torridon, and the Mg-sulfate-bearing strata that lies above it, with excursions onto the Greenheugh Pediment and Amapari Marker Band. These unique stratigraphic units were investigated using Curiosity's instrument suite which includes the Mast Camera (Mastcam) pair of multispectral imagers. Mastcam’s narrowband filters are sensitive to iron-bearing phases and some hydrated minerals. We used Mastcam spectra, in combination with chemical data from Curiosity’s CheMin, APXS and ChemCam instruments, to assess …