Physical Sciences and Mathematics Commons^™

Characterization Of The Ch Addition Product From Meta- And Ortho-Xylene + Ch Reaction And Direct Experimental Observation Of The Tetrabromine Cluster Br4 Using Synchrotron Photoionization Mass Spectrometry, Rory R. Mcclish

Master's Theses

This thesis is centered on the use of a unique gas-phase spectroscopy technique to characterize products and elucidate reaction mechanisms. Experiments were carried out at the Chemical Dynamics Beamline 9.0.2 of the Advanced Light Source located at the Lawrence Berkeley National Laboratory in Berkeley, CA. Computational work was performed on the scientific supercomputer at USF to supplement experimental findings. Chapter 1 contextualizes the work spurred in response to the deleterious interactions of anthropogenic emissions on Earth’s climate. Chapter 2 describes the theoretical manipulations foundational to the experimental design and interpretation. Chapter 3 delves into the physical details of the experimental …

Brown Dwarf Atmospheres At High Cadence And Spectral Resolution: A Speed Limit On Brown Dwarf Rotation And A Spectroscopic Atlas Of A 1050 K Atmosphere, Megan E. Tannock

Electronic Thesis and Dissertation Repository

Brown dwarfs are sub-stellar objects that form like stars but are not sufficiently massive to sustain hydrogen fusion in their cores. Characterized by cool, molecule-rich atmospheres, brown dwarfs demonstrate great diversity in spectroscopic appearance and share many properties with giant exoplanets. In this thesis I present two investigations: the first is a detailed photometric and spectroscopic study of the three most rapidly rotating brown dwarfs. The second examines a spectrum of a cool brown dwarf at unprecedented spectral resolution and signal-to-noise ratio to study the accuracy of theoretical model photospheres.

Photometric monitoring of brown dwarfs has revealed that periodic variability …

Ultrafast Spectroscopy Of Air Lasing In Filaments, Brian Robert Kamer

Optical Science and Engineering ETDs

Filamentation in air is a phenomenon that has been extensively investigated for the last two decades. At sufficiently high intensity, even air is a nonlinear medium. These intensities are reached with ultrashort pulses (50 to 100 fs) of more than 1 J energy, which self-focus in air, reach ionizing intensities of oxygen and nitrogen, creating a plasma that defocuses the beam. The air filament is a self-induced waveguide resulting from a balance of focusing and defocusing. In this work new techniques were developed to visualize and analyze this phenomenon through its emission, in particu- lar the UV emission of the …

Non-Linear Optical Characterization Of Stressed Materials, Kaylee N. Rellaford

Theses and Dissertations

Interactions between materials, their surfaces, and applied stresses are involved in every man-made construction in the world. Therefore, finding ways to interact without altering inherent properties of materials is of great interest. Surface spectroscopies, including second harmonic generation (SHG) and sum frequency generation (SFG), are inherently noninvasive testing methods. Both SHG and SFG are well-developed techniques that can be used in various applications including the characterization of material state. Both of these techniques allow for a noninvasive analysis of various materials, such as metals and polymers. We have used SHG as a method to characterize the change in signal strength …

The Profound Photophysical Effects Of Organic Chromophore Connectivity And Coupling, David J. Walwark Jr

Nanoscience and Microsystems ETDs

Through-bond and through-space interactions between chromophores are shown to have wide-ranging effects on photophysical outcomes upon light absorption in organic molecules. In collapsed poly(3-hexylthiophene), through-space coupling creates hybrid chromophores that act as energy sinks for nearby excitons and favorable sites for molecular oxygen to dock. Upon excitation with visible light the highly-coupled chromophores react with the docked oxygen and subsequently do not quench nearby excitons as efficiently. In tetramer arrays of perylene diimide chromophores the central moiety through-bond connectivity is synthesized in two variants which exhibit vastly different single-molecule blinking behavior and theoretically-predicted electronic transition character. In the more-connected tetramer …

Antibiotic Sensitivity Testing Of Foodborne Bacteria Using Surface-Enhanced Raman Spectroscopy, Joshua Gukowsky

Doctoral Dissertations

The spread of antibiotic resistant bacteria around the world has become a major public health issue, and it is essential that effective detection methods exist for identifying these organisms and preventing them from spreading throughout our food systems and into the environment. The goal of this research is to develop a novel analytical procedure that is capable of easily identifying antibiotic resistance in bacterial samples, and also provides more information about the biochemical characteristics of the bacteria and their responses to antibiotic exposure. Surface-enhanced Raman Spectroscopy (SERS), an analytical technique that uses light scattering to produce a spectrum based on …

Neutron Energy Tuning Assemblies For Nuclear Weapon Environment Applications At The National Ignition Facility, Nicholas J. Quartemont

Theses and Dissertations

An energy tuning assembly was developed to spectrally shape the National Ignition Facility deuterium-tritium fusion neutron source to a notional thermonuclear and prompt fission neutron spectrum to fulfill neutron source capability gaps. The experimental neutron environment was characterized with activation dosimetry, neutronics and covariance models, and unfolded to determine the as-fielded neutron spectrum. The first energy tuning assembly was demonstrated to create synthetic spectrally accurate post-detonation fission products, enhancing U.S. technical nuclear forensics capabilities. ATHENA, a second-generation energy tuning assembly, was also optimized to meet similar objectives, but the new platform neutron fluence efficiency was increased by a factor of …

Linear And Non Linear Properties Of Two-Dimensional Exciton-Polaritons, Mandeep Khatoniar

Dissertations, Theses, and Capstone Projects

Technology has been accelerating at breakneck speed since the first quantum revolution, an era that ushered transistors and lasers in the late 1940s and early 1960s. Both of these technologies relied on a matured understanding of quantum theories and since their inception has propelled innovation and development in various sectors like communications, metrology, and sensing. Optical technologies were thought to be the game changers in terms of logic and computing operations, with the elevator pitch being "computing at speed of light", a fundamental speed limit imposed by this universe’s legal system (a.k.a physics). However, it was soon realized that that …

Investigation Of The Interface Reactions Of Ion Selective Electrode Membranes Using Chromatographic And Spectroscopic Analyses Of Erbium(Iii) Tetraphenylporphyrin, Alexis Rae Miller

MSU Graduate Theses

Ion selective electrodes (ISEs) are analytical sensors that monitor the interactions between an ionophore within a polymeric membrane and ions in various solutions. The sensitivity and selectivity of ISEs is directly related to the chemical components. One type of ionopohore utilized in ISEs are metalloporphyrins. Metalloporphyrins have unique binding characteristics, which make them useful in sensors. The polymeric membranes that are synthesized and used in ISEs consist of a metalloporphyrin complex, polyvinyl chloride, and ortho-nitrophenyl octyl ether. The membrane unique to this project contains erbium (III) tetraphenylporphyrin as the metalloporphyrin ionophore. Various analytical techniques were applied in the investigation …

Spectroscopic Properties Of Ferroic Superlattices, Shiyu Fan

Doctoral Dissertations

The interplay between charge, structure, magnetism, and orbitals leads to rich physics and exotic cross-coupling in multifunctional materials. Superlattices provide a superb platform to study the complex interactions between different degrees of freedom. In this dissertation, I present a spectroscopic investigation of natural and engineered superlattices including Fe_xTaS₂ and (LuFeO₃)_m/(LuFe₂O₄)₁ under external stimuli of temperature and magnetic field as well as chemical substitution. Studying the phase transitions, symmetry-breaking, and complex interface interactions from a microscopic viewpoint enhances fundamental understanding of coupling mechanism between different order parameters and the …

High Frequency Electron Spin Resonance Investigations On Quasi-Two-Dimensional Chromium Halide Magnets, Christian Saiz

Open Access Theses & Dissertations

Broadening the knowledge and understanding on the magnetic correlations in van der Waals layered magnets is critical in realizing their potential next-generation applications in devices such as spintronics. In this study, we employ high frequency (ν = 120 GHz, 240 GHz) electron spin resonance (ESR) spectroscopy on plate-like CrX3 (where X = Cl, Br, I) to gain insight into the magnetic interactions as a function of temperature (200 – 4.4 K) and the angle of rotation θ (degrees). We find that the temperature dependence of the ESR linewidth is well described by the Ginzburg-Landau critical model, indicative of antiferromagnetic correlations …

Investigation Of G Protein-Coupled Receptor Quaternary Structure Through Fluorescence Micro-Spectroscopy And Theoretical Modeling: Interdependence Between Receptor-Receptor And Receptor-Ligand Interactions, Joel David Paprocki

Theses and Dissertations

Proteins are of high interest in biophysics research due to the important roles they play within cells, such as sensing of chemical (ions and small molecules) and physical (e.g., light) stimuli, providing structure, transporting ions/molecules, signaling, and intercellular communication. The studies described in this dissertation focus on a particular type of membrane proteins known as G protein-coupled receptors (GPCR), which play a key role in cellular response to external stimuli. We used the sterile 2 α-factor mating pheromone receptor (Ste2), a prototypical class D GPCR present within Saccharomyces cerevisiae (baker’s yeast). Ste2 is responsible for initiating the second messenger signal …

A Project To Dye For : Differentiation Of Dyed And Non-Dyed Human Hairs Using Atr Ft-Ir Spectroscopy, Joseph John Greco

Legacy Theses & Dissertations (2009 - 2024)

IR spectroscopy is widely utilized for forensic purposes due to the chemical fingerprint the method provides. ATR FT-IR spectroscopy is particularly advantageous because it allows for spectra to be collected quickly, accurately, and perhaps most importantly for forensics, non-destructively. Human hair is commonly collected at a crime scene, and further analyzed using DNA analysis and microscopy. However, these techniques have limitations. In the past ATR FT-IR spectroscopy has shown promise in the analysis of human hair for forensic purposes. In this study, the differentiation of undyed hair versus dyed hair classes of varying colors based on their IR spectra were …

Spectroscopic Analysis Of Potential Astromolecules Via Quantum Chemical Quartic Force Fields, Mason Gardner

Honors Theses

Astrochemistry has been substantially aided by computational techniques, particularly through the use of Quartic Force Field (QFF) analysis. Several methods have proven useful at correlating computed spectroscopic data with experimental observations. The F12-TZ QFF correlated well with experimental data for silicon oxide compounds, particularly those potentially involved in development from rocky bodies to planetary masses [27]. Compared to argon matrix experimental data, the vibrational frequencies for the molecules SiO2, SiO3, Si2O3, and Si2O4 become less accurate as the complexity of the molecules increases but should still be predictive of infrared characteristics of silicon oxides as they form clusters in space …

Conservation Of Polyester-Urethane Magnetic Audio Tapes And Discrimination Of Textile Fiber Dyes Using Spectroscopy And Chemometrics, Nilmini Hemanthika Ratnasena

Theses and Dissertations

This dissertation explores and discusses conservation of magnetic audio tapes and discrimination of fiber dyes employing spectroscopic techniques and chemometrics.

Conservation of polyester urethane magnetic audio tapes has become a major challenge since they are susceptible to degradation via hydrolysis. The world’s modern cultural history is vastly recorded in this media, and now conservationists need a non-destructive technique to determine the playability status of these tapes. Once conservationists identify degraded tapes, they can be subjected to the baking process. This process temporarily reverses hydrolysis and provides enough time to digitize tapes, preserving information for future generations. The first three chapters …

Photoemission Investigation Of Topological Quantum Materials, Klauss M. Dimitri

Honors Undergraduate Theses

Topological insulators (TIs) are a class of quantum materials, which behave as insulators in the bulk, yet possess gapless spin-polarized surface states, which are robust against nonmagnetic impurities. The unique properties of TIs make them attractive not only for studying various fundamental phenomena in condensed matter and particle physics, but also as promising candidates for applications ranging from spintronics to quantum computation. Within the topological insulator realm, a great deal of focus has been placed on discovering new quantum materials, however, ideal multi-modal quantum materials have yet to be found. Here we study alpha-PdBi2, KFe2Te2, and DySb compounds including others …

Martian Spectroscopy: Laboratory Calibration Of The Perseverance Rover’S Mastcam-Z And Photometric Investigation Of Mars-Analog Ferric-Coated Sand, Kristiana Lapo

WWU Graduate School Collection

The Mars 2020 rover Perseverance will search for signs of past habitability and biosignatures after landing in Jezero Crater in February 2021. Spectroscopy is a vital tool for planetary remote sensing and Perseverance is equipped with Mastcam-Z, a stereoscopic, zoom-enabled, multispectral imager that can acquire true color images with red, green, and blue (RGB) color filters, and visible- to near-infrared images with 12 narrowband science filters between 400 and 1100 nm. Mastcam-Z will provide operational support for the rover as well as directly contribute to Perseverance’s geologic investigations. Given the integral role of Mastcam-Z in the Mars 2020 mission, calibration …