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Articles 1 - 7 of 7
Full-Text Articles in Physics
The Kinetics Following Photolysis Of Nitrosyl Bromide, Lori A. Mahoney
The Kinetics Following Photolysis Of Nitrosyl Bromide, Lori A. Mahoney
Theses and Dissertations
One candidate for the development of a tunable laser in the mid-infrared for use as a defensive countermeasure against passive sensors exploits the nitric oxide (NO) transition at 5.4 μm. However, the difficulty with this mechanism is that when bromine (Br2) and NO are present in a mixture, nitrosyl bromide (BrNO) is also created. The absorption bands present in BrNO complicate the design of such a laser. This thesis determines the forward and reverse rate constants of the reaction of Br2 and NO to form BrNO following the photolysis of BrNO using Fourier Transform Infrared absorption spectroscopy. …
Design And Model Verification Of An Infrared Chromotomographic Imaging System, Daniel A. Lemaster
Design And Model Verification Of An Infrared Chromotomographic Imaging System, Daniel A. Lemaster
Theses and Dissertations
A prism chromotomographic hyperspectral imaging sensor is being developed to aid in the study of bomb phenomenology. Reliable chromotomographic reconstruction depends on accurate knowledge of the sensor specific point spread function over all wavelengths of interest. The purpose of this research is to generate the required point spread functions using wave optics techniques and a phase screen model of system aberrations. Phase screens are generated using the Richardson-Lucy algorithm for extracting point spread functions and Gerchberg-Saxton algorithm for phase retrieval. These phase screens are verified by comparing the modeled results of a blackbody source with measurements made using a chromotomographic …
Using Time-Resolved Photoluminescence To Measure The Excitation And Temperature Dependence Of Carrier Relaxation In Mid-Wave Infrared Semiconductors, Kevin Cumblidge
Using Time-Resolved Photoluminescence To Measure The Excitation And Temperature Dependence Of Carrier Relaxation In Mid-Wave Infrared Semiconductors, Kevin Cumblidge
Theses and Dissertations
Research in the field of mid-wave infrared (MWIR) semiconductor photonic devices has led to applications in a variety of disciplines including atmospheric monitoring, optical communications, non-invasive glucose testing for diabetics, and infrared (IR) countermeasures. One of the limiting factors for improving the modulation rates of MWIR devices is the carrier relaxation time. This is the time required for energetic carriers to cool to the edge of their respective bands in a bulk semiconductor material, or to the bottom of a well through inter- and intra-sub-band scattering in a quantum well (QW) structure. From these lower energy states, they can then …
Deviation Of Time-Resolved Luminescence Dynamics In Mwir Semiconductor Materials From Carrier Recombination Theory Predictions, Peter M. Johnson
Deviation Of Time-Resolved Luminescence Dynamics In Mwir Semiconductor Materials From Carrier Recombination Theory Predictions, Peter M. Johnson
Theses and Dissertations
Time resolved luminescence spectroscopy was used to characterize luminescence decay curves for a bulk InAs sample and an InAsSb type-I quantum-well sample over the first 3ns following excitation. The luminescence decay curves were then converted to carrier densities and used to find recombination coefficients that provided the least-squared-error solution of the rate equation describing carrier recombination. Recombination coefficients describing Shockley Read-Hall (ASRH) radiative (Brad) and Auger (CAug) recombination were determined at two different temperatures and four excitation powers, then analyzed for consistency and physical significance. For all of the resulting least …
Optical Characterization And Modeling Of Compositionally Matched Indium Arsenide-Antimonide Bulk And Multiple Quantum Well Semiconductors, Scott C. Phillips
Optical Characterization And Modeling Of Compositionally Matched Indium Arsenide-Antimonide Bulk And Multiple Quantum Well Semiconductors, Scott C. Phillips
Theses and Dissertations
Indium arsenide-antimonide (InAsSb) semiconductors have been determined to emit in the 3-5 micrometer range, the window of interest for countermeasures against infrared electro-optical threats. This experiment set out to cross the bulk to quantum well characterization barrier by optically characterizing two sets of compositionally matched type I quantum well and bulk well material samples. Absorption measurements determined the band gap energy of the bulk samples and the first allowed subband transition for the quantum wells. By collecting absorption spectra at different temperatures, the trend of the energy transitions was described by fitting a Varshni equation to them. The expected result …
Analysis Of Uncertainties In Infrared Camera Measurements Of A Turbofan Engine In An Altitude Test Cell, Thomas A. Morris
Analysis Of Uncertainties In Infrared Camera Measurements Of A Turbofan Engine In An Altitude Test Cell, Thomas A. Morris
Theses and Dissertations
This research investigated the uncertainties in measuring the IR signature of a General Electric F110-GE-129 turbofan engine inside an altitude test cell. The requirements for the measurement system include the intensity and radiance of the engine surfaces in three bands of operation, two Medium Wave IR (MWIR) bands and one Long Wave IR (LWIR) band. The altitude test cell provides a venue for measuring the IR signature in simulated altitude operation, but the imaging process is laden with measurement uncertainty due to stray radiation from the facility structure, hot exhaust gases, and the measurement equipment itself. The atmosphere and a …
A Rapidly-Converging Alternative To Source Iteration For Solving The Discrete Ordinates Radiation Transport Equations In Slab Geometry, Nicholas J. Wager
A Rapidly-Converging Alternative To Source Iteration For Solving The Discrete Ordinates Radiation Transport Equations In Slab Geometry, Nicholas J. Wager
Theses and Dissertations
I present a numerical technique to solve the time independent Boltzmann Transport Equation for the transport of neutrons and photons. The technique efficiently solves the discrete ordinates equations with a new iteration scheme. I call this new scheme the angle space distribution iteration method because it combines a non-linear, high angular-resolution flux approximation within individual spatial cells with a coarse angular-resolution flux approximation that couples all cells in a spatial mesh. This shown to be an efficient alternative to source iteration. The new method is implemented using the step characteristic and exponential characteristic spatial quadrature schemes. The latter was introduced …