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Optical Spectroscopy And Chemometrics For Discrimination Of Dyed Textile Fibers And Magnetic Audio Tapes, Nathan C. Fuenffinger

Theses and Dissertations

This dissertation focuses on the application of both novel and standard chemometric approaches toward societal problems of interest in the areas of forensic science and cultural heritage preservation. Microspectrophotometry (MSP), a technique enabling measurements of absorption of electromagnetic radiation by microscopic materials in the ultraviolet-visible (UV-Vis) region, is widely used by forensic examiners for comparisons of metameric textile fibers. These comparisons are often hindered, however, by the raw or normalized spectra showing little detail or having few points of comparison. Derivative preprocessing can enhance structure in some instances. We have demonstrated through the use of multivariate statistics that derivatives are …

Strontium Monoxide Measurements In Methane-Air Flames, Bobby J. Wimberly

Masters Theses

The spectroscopy of alkaline earth metal compounds has been an area of active research for several decades. This is at least in part stimulated by the application of these compounds to practical areas ranging from technology to medicine. The use of these compounds in the field of pyrotechnics was the motivation for a series of flame emission spectroscopy (FES) experiments with strontium containing compounds. Specifically, strontium monoxide (SrO) is studied as a candidate radiator for the diagnostic of methane-air flames.

SrO emissions have been observed in flames with temperatures in the range of 1200-1600-K for two compounds: strontium hydroxide and …

Reflectance And Emission Spectroscopy: Curve Fitting Methods With Application To Impact Glasses And The Varying Grain Size Of Planetary Analogue Minerals, Michael A. Craig

Electronic Thesis and Dissertation Repository

Spectroscopy, i.e., the measurement of electromagnetic radiation as a function of wavelength, is arguably the technique most responsible for the majority of what is collectively known about the composition of stars, the distances to galaxies, the age of the universe and so on. Spectroscopy is also the tool most used to discern the mineralogy of planetary bodies remotely. Measuring the speed at which a star is receding and its composition, or the composition of an interstellar cloud of gas are well understood uses of spectroscopy. When it comes to spectroscopies use to discern mineralogy, the scientific literature on the subject …

Low Intensity Gamma-Ray Spectroscopy Of The Lake Labyrinth Meteorite, Tristan C. Paul

Physics

A 23.7g fragment of the Lake Labyrinth Meteorite (fell in 1924, collected in 1934 at Lake Labyrinth in South Australia, Australia) was re-investigated for evidence of the presence of 98Tc using a two dimensional low-intensity gamma-ray spectrometer. A new calibration technique using 26Al sources found the gamma-rays previously thought to be due to 98Tc are more likely from 166Ho. The presence of 166Ho is most likely due to activation of the stable 165Ho in the meteorite from terrestrial background sources where it was stored.

Solubility And Detectability Of Hydrocarbons On The Surface Of Titan, Sandeep Singh

Graduate Theses and Dissertations

Titan’s thick atmosphere is enriched with organic compounds and its surface holds reservoirs of hydrocarbons. This makes Titan the only other candidate in our solar system (apart from Earth) to have stable liquid at the surface. The stability and characteristics of liquid and ices on the surface of Titan are of high importance in understanding its surface-atmosphere interactions. Titan’s hydrological cycle is similar to what we see on Earth, with the exception of methane (CH4) and ethane (C2H6) taking the place of water. The smoggy atmosphere veils the surface of Titan from the view of Cassini spacecraft, except at seven …

Coupling Nuclear Induced Phonon Propagation With Conversion Electron Mössbauer Spectroscopy, Michael J. Parker

Theses and Dissertations

Mössbauer spectroscopy is a very sensitive measurement technique (10^-8 eV) which prompted motivation for the experiment described in this thesis. Namely, can a sensitive detection system be developed to detect nuclear recoils on the order of 10 to 100 of eVs? The hypothesis that this thesis tests is: Nuclear induced phonon bursts caused by Rutherford scattered alphas, decayed from ²⁴¹Am, in a type-310 stainless steel material can couple with 7.3 keV conversion electron Mössbauer events at the other end of the material which will have a statistically significant effect on a Mössbauer spectrum. The phonon bursts produced by …

Differentiation Of Human, Animal And Synthetic Hair By Atr Ftir Spectroscopy, Jeremy Manheim

Chemistry

Hair fibers are ubiquitous to every environment and are the most commonly found form of trace evidence at crime scenes. The primary difficulty forensic examiners face after retrieving a hair sample is determining who it came from. Currently, the methodology of microscopic examination of potential hair evidence is absent of statistical probability and is inherently subjective. Another method, involving DNA analysis, takes months to conduct and the majority of times is unsuccessful due to its degradation and absence from the hair. Here, Attenuated Total Reflectance (ATR) Fourier Transform Infrared (FTIR) Spectroscopy coupled with advanced statistics was used to identify a …

Measuring The Hyperfine Splittings Of Lowest Energy Atomic Transitions In Rubidium, Benjamin D. Graber

Undergraduate Honors Thesis Projects

The goal of this experiment was to measure the hyperfine energy splittings of the ground to first excited state transitions in rubidium using saturated absorption spectroscopy. Using this technique, we measured these transition energy spectra by taking the difference of two photodiode outputs due to multiple beams of a single laser scanned over a range of frequencies and shone through a cell of Rb vapor. When the laser frequency was resonant with an atomic transition, photons of those frequencies were absorbed, leaving a dip in intensity of the beam measured at the photodiode. One of the two laser beams had …

Mueller Matrix Spectroscopic Ellipsometry Of Multiferroics, Roman Basistyy

Dissertations

Multiferroics, materials which possess several ferroic orders, are the focus of research in recent years. Among these materials are oxide crystals, such as, for example, RMnO₃, RMn₂O₅, R₃Fe₅O₁₂, where R stands for rare earth ions. The most fascinating physics occurs when magnon-lattice coupling reveals itself in the far-IR spectra of multiferroics. The expected optical behavior puts multiferroics into a more general category of bi-anisotropic materials, the properties of which could be only described using anisotropic dielectric ε(ω), magnetic μ(ω), and …

Synchrotron Based Infrared Microspectroscopy Of Carbonaceous Chondrites., Mehmet Yesiltas

Electronic Theses and Dissertations

Relationships between organic molecules and inorganic minerals are investigated in five carbonaceous chondrites, Northwest Africa 852 (CR2), Tagish Lake (C2-ungroupped), Orgueil (CI1), Sutter's Mill (CM), and Murchison (CM2), with micron spatial resolution using synchrotron-based imaging micro-FTIR spectroscopy. Correlations based on absorption strength for various constituents are determined using statistical correlation analysis. Silicate band is found to be positively correlated with stretching modes of aliphatic hydrocarbons in NWA 852 and Tagish Lake. The former is highly correlated with the hydration band in all meteorites. Negative correlation is observed between water+organics and carbonate bands in all meteorites. Two dimensional infrared maps for …

The Spectroscopic Characterization Of Newly Developed Emissive Materials And The Effects Of Environment On Their Photophysical Properties, Louis Edward Mcnamara

Electronic Theses and Dissertations

The development of new materials capable of efficient charge transfer and energy storage has become increasingly important in many areas of modern chemical research. This is especially true for the development of emissive optoelectronic devices and in the field of solar to electric energy conversion. The characterization of the photophysical properties of new molecular systems for these applications has become critical in the design and development of these materials. Many molecular building blocks have been developed and understanding the properties of these molecules at a fundamental level is essential for their successful implementation and future engineering. This dissertation focuses on …

Pulsed Inductive Plasma Studies By Spectroscopy And Internal Probe Methods, Warner C. Meeks

Doctoral Dissertations

The broad effort of the Missouri Plasmoid Experiment is to elucidate the energy conversion processes in a pulsed inductive discharge due to the presence of plasma. The test article is a 440 to 490 kHz theta-pinch (or solenoidal) geometry coil with a stored energy of around 80 joules. In this work experimental hydrogen, helium, argon and xenon data at back-fill pressures of 10 to 100 mTorr (1.3 to 133.3 Pa) are obtained and interpreted. Spectral and internal probe studies were performed on MPX Mk.I and Mk.II devices, respectively. IR spectra were acquired in the Mk.I device for argon and xenon. …

Investigating The Photorecombination Dynamics In Molecular High-Harmonic Spectra, Benjamin Parker Wilson

LSU Doctoral Dissertations

The work presented in this dissertation will relate the photorecombination dynamics to photoionization dynamics in SF6 utilizing the self-probing mechanism, high harmonic generation (HHG). This work specifically aims to establish parameters for which the comparison is applicable and the macroscopic complications inherent in HHG do not interfere with the extraction of dynamic information. The first part of this work established the macroscopic experimental apparatus necessary for consistent spectroscopic observation. It is shown that using a gas jet that is an order of magnitude shorter than the Rayleigh length of the driving laser results in more consistent harmonic spatial profiles and …

Photoelectrons And Recombining Electrons In Atomic And Molecular Systems, Kristen D'Ann Fulfer

LSU Doctoral Dissertations

This work in this dissertation explores how photoelectrons enter and exit atoms and molecules. The electron rescattering events which may occur during photoionization or photorecombination processes play a dominant role in the understanding of how photoelectrons enter and exit molecules, which is intrinsically linked to how chemical reactions occur. Chapters 3-4 of this dissertation present evidence of vibrational mode specific breakdown of the Franck-Condon Principle in the photoionization of low symmetry molecules, acrolein and the singly halogenated thiophenes, due to resonant and non-resonant electron rescattering dynamics. In Chapters 5-6, the disentanglement of the valence electronic structure, as well as evidence …