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Full-Text Articles in Chemistry
Spectroscopy Of Atmospheres, Randika Dodangodage
Spectroscopy Of Atmospheres, Randika Dodangodage
Physics Theses & Dissertations
Spectroscopic methods are used to study planetary and stellar atmospheres. The information obtained from spectroscopic studies provides insight into atmospheric compositions and dynamics, which can be used to model and characterize atmospheres and climates. Laboratory-recorded absorption cross-sections are needed to interpret the recorded spectra of planets and stars. High resolution ethane, neopentane, propene, and n-butane spectra have been recorded, and absorption cross-sections have been provided for different temperatures and total pressures with different broadening gases, including hydrogen, helium, and nitrogen. The Atmospheric Chemistry Experiment (ACE) satellite orbits Earth and records spectra through solar occultation limb observations. HOCl is a chlorine …
Engineering Rare-Earth Based Color Centers In Wide Bandgap Semiconductors For Quantum And Nanoscale Applications, Gabriel I. López-Morales
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 …
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 Profound Photophysical Effects Of Organic Chromophore Connectivity And Coupling, David J. Walwark Jr
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 …
Synthesis Of Graphene Using Plasma Etching And Atmospheric Pressure Annealing: Process And Sensor Development, Andrew Robert Graves
Synthesis Of Graphene Using Plasma Etching And Atmospheric Pressure Annealing: Process And Sensor Development, Andrew Robert Graves
Graduate Theses, Dissertations, and Problem Reports
Having been theorized in 1947, it was not until 2004 that graphene was first isolated. In the years since its isolation, graphene has been the subject of intense, world-wide study due to its incredibly diverse array of useful properties. Even though many billions of dollars have been spent on its development, graphene has yet to break out of the laboratory and penetrate mainstream industrial applications markets. This is because graphene faces a ‘grand challenge.’ Simply put, there is currently no method of manufacturing high-quality graphene on the industrial scale. This grand challenge looms particularly large for electronic applications where the …
Development Of A Ground-Based Aerial-Tracking Instrument For Open-Path Spectroscopy To Monitor Atmospheric Constituents, Haden Hodges
Development Of A Ground-Based Aerial-Tracking Instrument For Open-Path Spectroscopy To Monitor Atmospheric Constituents, Haden Hodges
Civil Engineering Undergraduate Honors Theses
A ground-based aerial-tracking instrument, known as the Ground Tracker, designed to provide spectral data to quantify greenhouse gases is under development. The Ground Tracker includes an Optical System including a high power rifle scope, video camera, and spectrometer used to locate an active light source from the Emitter, and collect spectral data by utilizing an actuating mirror. The implementation of this instrument could be made low cost by utilizing existing weather balloon infrastructure to allow the Emitter to be placed into the lower stratosphere. The recovery of the emitter will be possible by tracking the GPS coordinates. Weather balloon instrument …
Micro-Spectroscopy Of Bio-Assemblies At The Single Cell Level, Jeslin Kera
Micro-Spectroscopy Of Bio-Assemblies At The Single Cell Level, Jeslin Kera
Honors Undergraduate Theses
In this thesis, we investigate biological molecules on a micron scale in the ultraviolet spectral region through the non-destructive confocal absorption microscopy. The setup involves a combination of confocal microscope with a UV light excitation beam to measure the optical absorption spectra with spatial resolution of 1.4 μm in the lateral and 3.6 μm in the axial direction. Confocal absorption microscopy has the benefits of requiring no labels and only low light intensity for excitation while providing a strong signal from the contrast generated by the attenuation of propagating light due to absorption. This enables spatially resolved measurements of single …
Excitonic States In Crystalline Organic Semiconductors: A Condensed Matter Approach, Lane Wright Manning
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 …
Uv-Visible Microscope Spectrophotometric Polarization And Dichroism With Increased Discrimination Power In Forensic Analysis, Dale Kevin Purcell
Uv-Visible Microscope Spectrophotometric Polarization And Dichroism With Increased Discrimination Power In Forensic Analysis, Dale Kevin Purcell
All Open Access Legacy Dissertations and Capstone Projects
Microanalysis of transfer (Trace) evidence is the application of a microscope and microscopical techniques for the collection, observation, documentation, examination, identification, and discrimination of micrometer sized particles or domains. Microscope spectrophotometry is the union of microscopy and spectroscopy for microanalysis. Analytical microspectroscopy is the science of studying the emission, reflection, transmission, and absorption of electromagnetic radiation to determine the structure or chemical composition of microscopic-size materials. Microscope spectrophotometry instrument designs have evolved from monochromatic illumination which transmitted through the microscope and sample and then is detected by a photometer detector (photomultiplier tube) to systems in which broad-band (white light) illumination …
Speciation And Spectroscopy Of The Uranyl And Tetravalent Plutonium Nitrate Systems: Fundamental Studies And Applications To Used Fuel Reprocessing, Nicholas A. Smith
Speciation And Spectroscopy Of The Uranyl And Tetravalent Plutonium Nitrate Systems: Fundamental Studies And Applications To Used Fuel Reprocessing, Nicholas A. Smith
UNLV Theses, Dissertations, Professional Papers, and Capstones
This dissertation explores the use of UV-Visible spectroscopy and Time Resolved Laser Induced Fluorescence spectroscopy as near real time process monitors of uranium and plutonium concentrations in aqueous reprocessing trains. The molar absorptivities and linear ranges of these metals were investigated under total nitrate and acid concentrations similar to those found in current reprocessing systems. Concurrent to this, a new multiple wavelength monitor was derived that is capable of determining the total nitrate concentration spectroscopically. This method uses the uranium absorbance spectrum to calculate the nitrate concentration in solution. When used as part of an Advanced Safeguard suite, this technique …