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Articles 31 - 60 of 122
Full-Text Articles in Engineering Physics
Electrical Characterization Of Crystalline Uo2, Tho2 And U0.71Th0.29O2, Christina L. Dugan
Electrical Characterization Of Crystalline Uo2, Tho2 And U0.71Th0.29O2, Christina L. Dugan
Theses and Dissertations
Uranium dioxide (UO2), thorium dioxide (ThO2), and UxTh1-xO2 alloys are characterized for suitability in uranium-based neutron detectors. ThO2 was studied for an envisioned UO2/ThO2 heterojunction. A U0.71Th0.29O2 alloy was studied because of its resistance to oxidation and potential use in surface passivation. The U0.71Th0.29O2 effective Debye temperature of 217± 24 K was measured using temperature-dependent x-ray photoemission spectroscopy (XPS). The specific heat capacity for the U0.71Th0.29O2 alloy was calculated from the Debye …
Improving Detection Of Dim Targets: Optimization Of A Moment-Based Detection Algorithm, Shannon R. Young
Improving Detection Of Dim Targets: Optimization Of A Moment-Based Detection Algorithm, Shannon R. Young
Theses and Dissertations
Wide area motion imagery (WAMI) sensor technology is advancing rapidly. Increases in frame rates and detector array sizes have led to a dramatic increase in the volume of data that can be acquired. Without a corresponding increase in analytical manpower, much of these data remain underutilized. This creates a need for fast, automated, and robust methods for detecting dim, moving signals of interest. Current approaches fall into two categories: detect-before-track (DBT) and track-before-detect (TBD) methods. The DBT methods use thresholding to reduce the quantity of data to be processed, making real time implementation practical but at the cost of the …
Estimation Of Atmospheric Turbulence Using Differential Motion Of Extended Features In Time-Lapse Imagery, Santasri R. Bose-Pillai, Jack E. Mccrae, Christopher A. Rice, Ryan A. Wood, Conner E. Murphy, Steven T. Fiorino
Estimation Of Atmospheric Turbulence Using Differential Motion Of Extended Features In Time-Lapse Imagery, Santasri R. Bose-Pillai, Jack E. Mccrae, Christopher A. Rice, Ryan A. Wood, Conner E. Murphy, Steven T. Fiorino
Faculty Publications
We address the design, development, and testing of a pointer/tracker as a probe beam for the purpose of making high-speed, aero-optical measurements of the flow over a scaled beam director turret. The tracker uses retro-reflection of the probe beam off of a Reflexite annulus surrounding the turret. The constraints of the design required a near-total-commercial off the shelf system that could be quickly installed and removed in a rented aircraft. Baseline measurements of environmental vibrations are used to predict pointing performance; mitigation of line-of-sight jitter on the probe beam is achieved through passive isolation and the design of relay optics. …
Arrhenius Rate Chemistry-Informed Inter-Phase Source Terms (Arciist), Matthew J. Schwaab, Robert B. Greendyke, Bryan J. Steward
Arrhenius Rate Chemistry-Informed Inter-Phase Source Terms (Arciist), Matthew J. Schwaab, Robert B. Greendyke, Bryan J. Steward
Faculty Publications
Currently, in macro-scale hydrocodes designed to simulate explosive material undergoing shock-induced ignition, the state of the art is to use one of numerous reaction burn rate models. These burn models are designed to estimate the bulk chemical reaction rate. Unfortunately, these burn rate models are largely based on empirical data and must be recalibrated for every new material being simulated. We propose that the use of Arrhenius Rate Chemistry-Informed Interphase Source Terms (ARCIIST) in place of empirically derived burn models will improve the accuracy for these computational codes. A reacting chemistry model of this form was developed for the cyclic …
Two-Photon Excitation Of Cesium Alkali Metal Vapor 72D, 82D Kinetics And Spectroscopy, Ricardo C. Davila
Two-Photon Excitation Of Cesium Alkali Metal Vapor 72D, 82D Kinetics And Spectroscopy, Ricardo C. Davila
Theses and Dissertations
Pulsed excitation on the two-photon Cs 62S½ → 72D3/2,5/2 transition results in time-resolved fluorescence at 697 nm and 672 nm. The rates for fine structure mixing between the 72D3/2,5/2 states have been measured for helium and argon rare gas collision partners. The mixing rates are very fast, 1.26 ± 0.05 x 10-9 cm3/(atom sec) for He and 1.52 ± 0.05 x 10-10 cm3 /(atom sec) for Ar, driven by the small energy splitting and large radial distribution for the valence electron. …
A Comparison Of High Frequency Angle Of Arrival And Ionosonde Data During A Traveling Ionospheric Disturbance, Kalen L. Knippling
A Comparison Of High Frequency Angle Of Arrival And Ionosonde Data During A Traveling Ionospheric Disturbance, Kalen L. Knippling
Theses and Dissertations
High Frequency (HF) geolocation techniques are commonly used to track the source of uncooperative HF emitters. A traveling ionospheric disturbance (TID) makes geolocation particularly difficult due to large perturbations in the local ionospheric electron density profile. Angle of Arrival (AoA) and ionosonde virtual height measurements collected at White Sands Missile Range, New Mexico in January 2014, are analyzed during a medium scale traveling ionospheric disturbance. TID characteristics are extracted from the measurements, and a comparison between the data sets is per- formed to provide a measure of correlation as a function of distance and time between the ionosonde and AoA …
Comparison Of Plume Dynamics For Laser Ablated Metals: Al And Ti, William A. Bauer, Glen P. Perram, Timothy J. Haugan
Comparison Of Plume Dynamics For Laser Ablated Metals: Al And Ti, William A. Bauer, Glen P. Perram, Timothy J. Haugan
Faculty Publications
Emissive plumes from pulsed laser ablation of bulk Ti and Al from KrF laser irradiation at laser fluence up to 3.5 J/cm2 and argon background pressures of 0–1 Torr have been observed using gated intensified charged-coupled device imagery. Mass loss for Ti increases from 0.1 to 0.8 μg/pulse as pulse energy increase from 174 to 282 mJ/pulse (35–170 photons/atom) and decreases by ∼30% as pressure increases from vacuum to 1 Torr. Early plume energies are described by the free expansion velocities of 1.57 ± 0.02 and of 1.81 ± 0.07 cm/μs for Ti and Al, respectively, …
Copper-Doped Lithium Triborate (Lib3o5) Crystals: A Photoluminescence, Thermoluminescence, And Electron Paramagnetic Resonance Study, Brant E. Kananen, John W. Mcclory, Nancy C. Giles, Larry E. Halliburton
Copper-Doped Lithium Triborate (Lib3o5) Crystals: A Photoluminescence, Thermoluminescence, And Electron Paramagnetic Resonance Study, Brant E. Kananen, John W. Mcclory, Nancy C. Giles, Larry E. Halliburton
Faculty Publications
When doped with copper ions, lithium borate materials are candidates for use in radiation dosimeters. Copper-doped lithium tetraborate (Li2B4O7) crystals have been widely studied, but little is known thus far about copper ions in lithium triborate (LiB3O5) crystals. In the present investigation, Cu+ ions (3d10) were diffused into an undoped LiB3O5 crystal at high temperature. These ions occupy both Li+ and interstitial positions in the crystal. A photoluminescence (PL) band peaking near 387 nm and a photoluminescence excitation (PLE) band peaking near 273 nm verify that a portion of these Cu+ ions are located at regular Li+ sites. After an …
Statistical Photocalibration Of Photodetectors For Radiometry Without Calibrated Light Sources, Nicholas J. Yielding, Stephen C. Cain, Michael D. Seal
Statistical Photocalibration Of Photodetectors For Radiometry Without Calibrated Light Sources, Nicholas J. Yielding, Stephen C. Cain, Michael D. Seal
Faculty Publications
Calibration of CCD arrays for identifying bad pixels and achieving nonuniformity correction is commonly accomplished using dark frames. This kind of calibration technique does not achieve radiometric calibration of the array since only the relative response of the detectors is computed. For this, a second calibration is sometimes utilized by looking at sources with known radiances. This process can be used to calibrate photodetectors as long as a calibration source is available and is well-characterized. A previous attempt at creating a procedure for calibrating a photodetector using the underlying Poisson nature of the photodetection required calculations of the skewness of …
Gallium Vacancies In Β-Ga2O3 Crystals, Brant E. Kananen, Larry E. Halliburton, K. T. Stevens, G. K. Foundos
Gallium Vacancies In Β-Ga2O3 Crystals, Brant E. Kananen, Larry E. Halliburton, K. T. Stevens, G. K. Foundos
Faculty Publications
The gallium vacancy, an intrinsic acceptor, is identified in β-Ga2O3 using electron paramagnetic resonance (EPR). Spectra from doubly ionized (V2−Ga) and singly ionized (V−Ga) gallium vacancies are observed at room temperature, without photoexcitation, after an irradiation with high-energy neutrons. The V2−Ga centers (with S = 1/2) have a slight angular variation due to a small anisotropy in the g matrix (principal values are 2.0034, 2.0097, and 2.0322). The V2−Ga centers also exhibit a resolved hyperfine structure due to equal and nearly isotropic interactions with the …
Total Electron Count Variability And Stratospheric Ozone Effects On Solar Backscatter And Lwir Emissions, John S. Ross
Total Electron Count Variability And Stratospheric Ozone Effects On Solar Backscatter And Lwir Emissions, John S. Ross
Theses and Dissertations
The development of an accurate ionospheric Total Electron Content (TEC) model is of critical importance to High Frequency (HF) radio wave propagation. However, the TEC is highly variable and is continuously influenced by geomagnetic storms, extreme Ultraviolet (UV) radiation, diurnal variation, and planetary waves. The ability to capture this variability is essential to improve current TEC models. Analysis of the growing body of data involving ionospheric fluctuations and thermal tides has revealed persistent correlation between increases in stratospheric ozone and variability of the TEC. The spectral properties of ozone show that it is a greenhouse gas that alters longwave emissions …
Rbhe Potential Energy Surface Sensitivity Study, Ethan D. Thorp
Rbhe Potential Energy Surface Sensitivity Study, Ethan D. Thorp
Theses and Dissertations
This paper studies how alterations of features of RbHe potential energy surfaces (PES) for a diode pumped alkali laser (DPAL) system effect the collisional cross section. The Split-Operator method is used to propagate a wave function along these PES and because they are radially coupled, the wave function can be transmitted from the starting surface to other energy surfaces. This transmittance is encoded in the correlation function. The full Hamiltonian used for propagation consists of the electronic potential, the nuclear kinetic energy, and the Coriolis coupling. The correlation function is used to generate the Scattering Matrix elements. These elements describe …
Estimation Of Turbulence From Time-Lapse Imagery, Jack E. Mccrae, Santasri Bose-Pillai, Steven T. Fiorino
Estimation Of Turbulence From Time-Lapse Imagery, Jack E. Mccrae, Santasri Bose-Pillai, Steven T. Fiorino
Faculty Publications
Atmospheric turbulence parameters are estimated for an imaging path based on time-lapse imaging results. Atmospheric turbulence causes frame-to-frame shifts of the entire image as well as parts of the image. The statistics of these shifts encode information about the turbulence strength (as characterized by Cn2, the refractive index structure function constant) along the optical path. The shift variance observed is simply proportional to the variance of the tilt of the optical field averaged over the area being tracked and averaged over the camera aperture. By presuming this turbulence follows the Kolmogorov spectrum, weighting functions, which relate the turbulence strength along …
Simulation Of Anisoplanatic Imaging Through Optical Turbulence Using Numerical Wave Propagation With New Validation Analysis, Russell C. Hardie, Jonathan D. Power, Daniel A. Lemaster, Douglas Droege, Szymon Gladysz, Santasri Bose-Pillai
Simulation Of Anisoplanatic Imaging Through Optical Turbulence Using Numerical Wave Propagation With New Validation Analysis, Russell C. Hardie, Jonathan D. Power, Daniel A. Lemaster, Douglas Droege, Szymon Gladysz, Santasri Bose-Pillai
Faculty Publications
We present a numerical wave propagation method for simulating imaging of an extended scene under anisoplanatic conditions. While isoplanatic simulation is relatively common, few tools are specifically designed for simulating the imaging of extended scenes under anisoplanatic conditions. We provide a complete description of the proposed simulation tool, including the wave propagation method used. Our approach computes an array of point spread functions (PSFs) for a two-dimensional grid on the object plane. The PSFs are then used in a spatially varying weighted sum operation, with an ideal image, to produce a simulated image with realistic optical turbulence degradation. The degradation …
Evaluation Of Hydrothermally Synthesized Uranium Dioxide For Novel Semiconductor Applications, Christopher M. Young
Evaluation Of Hydrothermally Synthesized Uranium Dioxide For Novel Semiconductor Applications, Christopher M. Young
Theses and Dissertations
Neutron radiation detection is an important part of the national strategy for nonproliferation efforts worldwide. Key to the success of these programs is detector material development which establishes the limits of efficiency, sensitivity, and power usage for a detector of practical use. This research focused upon the study of neutron detection using single crystal actinide compounds, specifically UO2, taking advantage of the successful hydrothermal synthesis of UO2 at the Air Force Research Laboratories. Initial indications are that this material may be of sufficient quality for semiconductor application.
Estimation Of Temporal Variations In Path-Averaged Atmospheric Refractive Index Gradient From Time-Lapse Imagery, Santasri Basu, Jack E. Mccrae, Steven T. Fiorino, Jared Przelomski
Estimation Of Temporal Variations In Path-Averaged Atmospheric Refractive Index Gradient From Time-Lapse Imagery, Santasri Basu, Jack E. Mccrae, Steven T. Fiorino, Jared Przelomski
Faculty Publications
The sea level vertical refractive index gradient in the U.S. Standard Atmosphere model is −2.7×10−8 m−1 at 500 nm. At any particular location, the actual refractive index gradient varies due to turbulence and local weather conditions. An imaging experiment was conducted to measure the temporal variability of this gradient. A tripod mounted digital camera captured images of a distant building every minute. Atmospheric turbulence caused the images to wander quickly, randomly, and statistically isotropically and changes in the average refractive index gradient along the path caused the images to move vertically and more slowly. The temporal variations of …
Direct Bandgap Cross-Over Point Of Ge1-YSnY Grown On Si Estimated Through Temperature-Dependent Photoluminescence Studies, Thomas R. Harris, Mee-Yi Ryu, Yung Kee Yeo, Buguo Wang, C. L. Senaratne
Direct Bandgap Cross-Over Point Of Ge1-YSnY Grown On Si Estimated Through Temperature-Dependent Photoluminescence Studies, Thomas R. Harris, Mee-Yi Ryu, Yung Kee Yeo, Buguo Wang, C. L. Senaratne
Faculty Publications
Epitaxial Ge1-ySny (y = 0%–7.5%) alloys grown on either Si or Ge-buffered Si substrates by chemical vapor deposition were studied as a function of Sn content using temperature-dependent photoluminescence (PL). PL emission peaks from both the direct bandgap (Γ-valley) and the indirect bandgap (L-valley) to the valence band (denoted by ED and EID, respectively) were clearly observed at 125 and 175 K for most Ge1-ySny samples studied. At 300 K, however, all of the samples exhibited dominant ED emission with either very weak or no measureable EID emission. At 10 K, …
Tunable Split-Ring Resonators Using Germanium Telluride, Christopher H. Kodama, Ronald Coutu Jr.
Tunable Split-Ring Resonators Using Germanium Telluride, Christopher H. Kodama, Ronald Coutu Jr.
Faculty Publications
We demonstrate terahertz (THz) split-ring resonator (SRR) designs with incorporated germanium telluride (GeTe) thin films. GeTe is a chalcogenide that undergoes a nonvolatile phase change from the amorphous to crystalline state at approximately 200 °C, depending on the film thickness and stoichiometry. The phase change also causes a drop in the material's resistivity by six orders of magnitude. In this study, two GeTe-incorporated SRR designs were investigated. The first was an SRR made entirely out of GeTe and the second was a gold SRR structure with a GeTe film incorporated into the gap region of the split ring. These devices …
Capturing Atmospheric Effects On 3-D Millimeter Wave Radar Propagation Patterns, Richard D. Cook
Capturing Atmospheric Effects On 3-D Millimeter Wave Radar Propagation Patterns, Richard D. Cook
Theses and Dissertations
The need to model millimeter wave (MMW) radar propagation is imperative to proper design of aeronautical, civil, and military systems. Traditional radar propagation modeling is done using a path transmittance with little to no input for weather and atmospheric conditions. As radar advances into the MMW regime, atmospheric effects, such as attenuation and refraction, become more pronounced than at traditional radar wavelengths. The DoD High Energy Laser Joint Technology Offices High Energy Laser End-to-End Operational Simulation (HELEEOS), in combination with the Laser Environmental Effects Definition and Reference (LEEDR) code, is a powerful tool for simulating laser propagation and effects tied …
Generating Partially Coherent Schell-Model Sources Using A Modified Phase Screen Approach, Milo W. Hyde Iv, Santasri Basu, David G. Voelz, Xifeng Xiao
Generating Partially Coherent Schell-Model Sources Using A Modified Phase Screen Approach, Milo W. Hyde Iv, Santasri Basu, David G. Voelz, Xifeng Xiao
Faculty Publications
A significant improvement to the recently introduced complex screen (CS) method for generating partially coherent Schell-model sources is presented. The method, called the modified phase screen (MPS) technique, applies a deterministic amplitude and the phase portion of a CS to an initially coherent light source using a single phase-only spatial light modulator. The MPS technique, unlike the CS approach from which it is derived, does not produce a fully developed speckle pattern in the source plane, and therefore converges faster and more uniformly to the desired partially coherent source. The analytical development of the MPS method is presented. Experimental results …
Temperature Dependent Rubidium-Helium Line Shapes And Fine Structure Mixing Rates, Wooddy S. Miller
Temperature Dependent Rubidium-Helium Line Shapes And Fine Structure Mixing Rates, Wooddy S. Miller
Theses and Dissertations
Diode Pumped Alkali Lasers (DPALs) are a new type of laser that uses alkali metal vapor as a gain medium and a buffer gas to control the line shape and kinetics. While these systems were first demonstrated in 2003 [48] they have just recently been scaled to the kilowatt power levels in 2012 [18]. To achieve these powers, the design of the gain cell relied on a set of incomplete line shape and kinetic data. The current focus areas of DPAL research are the continued power scaling of the systems and basic science research into the rates involved within the …
Improved Terahertz Modulation Using Germanium Telluride (Gete) Chalcogenide Thin Films, Alexander H. Gwin, Christopher H. Kodama, Tod V. Laurvick, Ronald Coutu Jr., Philip F. Taday
Improved Terahertz Modulation Using Germanium Telluride (Gete) Chalcogenide Thin Films, Alexander H. Gwin, Christopher H. Kodama, Tod V. Laurvick, Ronald Coutu Jr., Philip F. Taday
Faculty Publications
We demonstrate improved terahertz (THz) modulation using thermally crystallized germanium telluride (GeTe) thin films. GeTe is a chalcogenide material that exhibits a nonvolatile, amorphous to crystalline phase change at approximately 200 °C, as well as six orders of magnitude decreased electrical resistivity. In this study, amorphous GeTe thin films were sputtered on sapphire substrates and then tested using THz time-domain spectroscopy (THz-TDS). The test samples, heated in-situ while collecting THz-TDS measurements, exhibited a gradual absorbance increase, an abrupt nonvolatile reduction at the transition temperature, followed by another gradual increase in absorbance. The transition temperature was verified by conducting similar thermal …
Identifying The Experimental And Theoretical Effective Characteristics Of Nonaligned Anisotropic Metamaterials, Michael R. Benson
Identifying The Experimental And Theoretical Effective Characteristics Of Nonaligned Anisotropic Metamaterials, Michael R. Benson
Theses and Dissertations
Previous research into anisotropic materials has assumed certain properties in order to make the underlying mathematics tractable. One of the assumptions is the alignment of the optical axes with the laboratory frame of reference, such as split-ring resonators lying at on the material plane. This assumption does not hold true for many metamaterials, such as tilted nanorods. Techniques such as ellipsometry are needed to analyze the effective characteristics of these highly anisotropic structures. In this research, tilted nanorods are analyzed using generalized ellipsometry to extract the indices of the optical axes. The underlying physics of ellipsometry is then used to …
Absorption Spectroscopy Of Rubidium In An Alkali Metal Dispenser Cell And Bleached Wave Analysis, James M. Rosenthal
Absorption Spectroscopy Of Rubidium In An Alkali Metal Dispenser Cell And Bleached Wave Analysis, James M. Rosenthal
Theses and Dissertations
An absorption spectrum of a rubidium alkali metal dispenser (AMD) cell was obtained in order to determine the system s suitability for use in a diode pumped alkali laser (DPAL) and use in high-temperature spectroscopic studies. The AMD produced a concentration of 3.65 0.16 1010 cm-3, which is in the ideal range for Beer s Law region absorption spectroscopy, but too low to make a high-power DPAL in a 10 cm cell with a poor Q resonator. Before AMDs can be used to determine pressure broadening and shifting coefficients, issues concerning contamination and producing rubidium vapor at pressure must be …
Scaling Of An Optically Pumped Mid-Infrared Rubidium Laser, Paul J. Moran
Scaling Of An Optically Pumped Mid-Infrared Rubidium Laser, Paul J. Moran
Theses and Dissertations
An optically pumped mid-infrared rubidium (Rb) pulsed laser has been demonstrated in a heat pipe along the 62P3/2 - 62S1/2 transition at 2.730 µm and the 62P1/2 - 62S1/2 transition at 2.790 µm. The bleached limit, slope efficiency, and maximum laser output energy of the mid-IR Rb laser have been shown to scale linearly with increasing Rb density, contrary to prior laser demonstrations. A maximum output energy of 5 nJ per pulse had previously been observed before a rollover occurred in the scaling of output energy with Rb …
Potential Energy Curves And Associated Line Shape Of Alkali-Metal And Noble-Gas Interactions, Larry A. Blank
Potential Energy Curves And Associated Line Shape Of Alkali-Metal And Noble-Gas Interactions, Larry A. Blank
Theses and Dissertations
Recent interest in optically-pumped alkali laser systems has prompted this study into the binary interaction potentials between species of alkali-metal and rare-gas atoms and the effects of the collision of these species on the alkali-metal atom absorption spectrum. Special attention is placed on the relationship of the interaction potentials and the resulting line shape. The X2Σ+1/2, A2π1/2, A2π3/2, and B2Σ+1/2 potential energy curves and associated dipole matrix elements are computed for M+ Ng at the spin-orbit multi-reference configuration interaction level, where M = …
Finite Element Analysis Modeling Of Chemical Vapor Deposition Of Silicon Carbide, Brandon M. Allen
Finite Element Analysis Modeling Of Chemical Vapor Deposition Of Silicon Carbide, Brandon M. Allen
Theses and Dissertations
Fiber-reinforced silicon carbide (SiC) composite materials are important for many applications due to their high temperature strength, excellent thermal shock and impact resistance, high hardness, and good chemical stability. The microstructure and phase composition of SiC composites can be tailored by fiber surface modification, the process parameters, and/or fiber preform architecture. One process by which SiC composites can be produced is chemical vapor deposition (CVD). This thesis primarily focuses on mass transport by gas-phase flow and diffusion, chemical reaction in gas phase and on solid surfaces, and thin film formation on curved surfaces, which are fundamental to the CVD process. …
Rare Earth Dopant (Nd, Gd, Dy, And Er) Hybridization In Lithium Tetraborate, Tony D. Kelly, James C. Petrosky, John W. Mcclory, Volodymyr T. Adamiv, Yaroslav V. Burak, Bohdan V. Padlyak, Ihor M. Teslyuk, Ning Lu, Lu Wang, Wai-Ning Mei, Peter A. Dowben
Rare Earth Dopant (Nd, Gd, Dy, And Er) Hybridization In Lithium Tetraborate, Tony D. Kelly, James C. Petrosky, John W. Mcclory, Volodymyr T. Adamiv, Yaroslav V. Burak, Bohdan V. Padlyak, Ihor M. Teslyuk, Ning Lu, Lu Wang, Wai-Ning Mei, Peter A. Dowben
Faculty Publications
The four dopants (Nd, Gd, Dy, and Er) substitutionally occupy the Li+ sites in lithium tetraborate (Li2B4O7: RE) glasses as determined by analysis of the extended X-ray absorption fine structure. The dopants are coordinated by 6-8 oxygen at a distance of 2.3 to 2.5 Å, depending on the rare earth. The inverse relationship between the RE-O coordination distance and rare earth (RE) atomic number is consistent with the expected lanthanide atomic radial contraction with increased atomic number. Through analysis of the X-ray absorption near edge structure, the rare earth dopants adopt the RE …
Development And Characterization Of A High Speed Mid-Ir Tunable Diode Laser Absorption Spectrometer For Co And Co2 Detection In Detonation Events, Stephen D. Wakefield
Development And Characterization Of A High Speed Mid-Ir Tunable Diode Laser Absorption Spectrometer For Co And Co2 Detection In Detonation Events, Stephen D. Wakefield
Theses and Dissertations
A tunable diode laser absorption spectroscopy system, capable of collecting data at a 10 kHz repetition rate near 4.5 microns. This system was made feasible in recent years due to the development of quantum cascade lasers active in the 4.5 microns region of the spectrum. Reaching into the mid-IR region of the electromagnetic spectrum allowed for an analysis of the fundamental absorption bands for both CO and CO2. The spectral absorption was measured for ethylene, methane, ethane, and propane across a variety of equivalence ratios, at various heights above a Hencken Burner surface. For each fuel, the concentration …
Iron-Doped Zinc Selenide: Spectroscopy And Laser Development, Jonathan W. Evans
Iron-Doped Zinc Selenide: Spectroscopy And Laser Development, Jonathan W. Evans
Theses and Dissertations
We examine the quantum mechanics of optically active ions in crystals. Insight is developed which qualitatively explains the shape of the optical absorption and emission spectra of Fe2+ ions in II-VI materials. In addition to a discussion of the relevant theory, this work explores experimental techniques for absorption spectroscopy, laser-induced fluorescence spectroscopy, and upper-state lifetime measurements in detail. The data collected from these experiments are interpreted in the context of the theories developed herein. The theory and data are used to develop a simple model of the temperature dependence of the upper-state lifetime of Fe2+ ions in ZnSe. …