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Non-Hermitian Physics Achieved Via Non-Local Gilbert Damping, Trevor Joshua Macintosh
Non-Hermitian Physics Achieved Via Non-Local Gilbert Damping, Trevor Joshua Macintosh
Electronic Theses and Dissertations
In this thesis, we study a simple model for a ferromagnet starting with Heisenberg exchange interaction including the effects of dissipation. Gilbert damping is consid- ered and generalized from an on-site term to include non-local damping interactions between neighbouring spins. The strength of the damping interaction between neigh- bours can be tuned individually to provide the freedom to change the parameters of the system and explore the range of possible non-Hermitian behaviours. We consider the example of a honeycomb lattice ferromagnet featuring Dirac cones and two sub- lattices and analyse the resulting spectra and eigenstates. Under periodic boundary conditions, we …
Stimulated Raman Spectroscopy With Widely Tunable Probe Pulse For Measuring Dissolved Inorganic Phosphorus In The Great Lakes, Nathan Gregory Drouillard
Stimulated Raman Spectroscopy With Widely Tunable Probe Pulse For Measuring Dissolved Inorganic Phosphorus In The Great Lakes, Nathan Gregory Drouillard
Electronic Theses and Dissertations
The eutrophication of freshwater ecosystems remains a persistent global problem threatening biodiversity, drinking water, and economic interests. Among the Laurentian Great Lakes, Lake Erie is most severely impacted by eutrophication, experiencing annual harmful algal blooms that are thought to result from excess phosphate deposition into the ecosystem. Efforts to study and mitigate the effects of eutrophication require accurate monitoring of phosphate concentrations. The current method for measuring phosphate, the molybdenum blue method, suffers from signal interference. In this thesis, I recommend Raman spectroscopy as a label-free, reagent-free spectroscopic technique for accurately measuring phosphate in freshwater. I verify the Raman spectrum …
Electromagnetically Induced Transparency In An Ensemble Of Three-Level Lambda Systems, Sara Moezzi
Electromagnetically Induced Transparency In An Ensemble Of Three-Level Lambda Systems, Sara Moezzi
Electronic Theses and Dissertations
Electromagnetically induced transparency (EIT) is a technique whereby a medium otherwise opaque to radiation of a particular frequency can be made transparent at that frequency by applying radiation of an appropriate second frequency. EIT demonstrates numerous current applications, with a notable focus on its utilization within the field of quantum information. Given the absence of an established theory of EIT in atomic ensembles, my primary focus is to develop theoretical models that describe both the quantum mechanical origin of EIT as well as the effect of interatomic interactions. In this thesis, I present two theoretical models of EIT in an …
Detection And Diagnosis Of Bacterial Pathogens In Blood And Urine Using Laser-Induced Breakdown Spectroscopy, Emma J.M. Blanchette
Detection And Diagnosis Of Bacterial Pathogens In Blood And Urine Using Laser-Induced Breakdown Spectroscopy, Emma J.M. Blanchette
Electronic Theses and Dissertations
The aim of this thesis is to expand on and improve the existing techniques used for detecting and identifying bacterial pathogens in clinical specimens with laser-induced breakdown spectroscopy (LIBS). Specifically, the existing experimental procedures, including bacterial sample preparation and data acquisition, as well as the data analysis with chemometric algorithms were investigated. Substantial reductions in LIBS background signal were achieved by implementing rigorous cleaning steps and the introduction of the use of ultrapure water. Following this, a database of LIBS spectra was acquired from specimens of E. coli, S. aureus, E. cloacae, M. smegmatis, and P. …
Calculated Charge State Distributions And Anisotropies Following The Β-Decay Of 6he, Eva E. Sculhoff
Calculated Charge State Distributions And Anisotropies Following The Β-Decay Of 6he, Eva E. Sculhoff
Electronic Theses and Dissertations
According to the standard model the beta-decay of 6He is a pure Gamow-Teller transition. The aim of this thesis is to provide theoretical support in the search for new physics beyond the standard model by examining the angular distribution of beta particles following decay. The simple structure of 6He, along with its ability to under go beta-decay into 6Li+ makes it an ideal candidate for studying the weak force. Due to the sudden increase in nuclear charge from Z = 2 to Z = 3, and the recoil momentum of the daughter nucleus resulting from the emitted leptons, this decay …
Quantitative Magnetic Resonance Imaging Methodology Development, Layale Bazzi
Quantitative Magnetic Resonance Imaging Methodology Development, Layale Bazzi
Electronic Theses and Dissertations
Magnetic Resonance Imaging (MRI) is a non-invasive medical imaging modality that provides excellent soft tissue contrast and resolution. Objects with high magnetic susceptibility distort the magnetic field, leading to severe artifacts in conventional MRI. It is very challenging to image around metal implants. Novel strategies may exploit the field distortion for spatial encoding. The magnetic field map is required in the development of these methods. A robust field map can also be employed to quantify high susceptibility particles that play a major role in cell tracking studies and hyperthermic treatment of cancers.
Pure phase encoding (PPE) techniques with short encoding …
Femtosecond Pulse Compression Via Self-Phase Modulation In 1-Decanol, Jacob A. Stephen
Femtosecond Pulse Compression Via Self-Phase Modulation In 1-Decanol, Jacob A. Stephen
Electronic Theses and Dissertations
Ultrafast science is a branch of photonics with far reaching applications in and outside the realm of physics. Ultrashort laser pulses on the order of femtoseconds (1 fs = 1 × 10−15 s) are widely used for ultrafast science. Many lasers can produce pulses on the order of 100 fs, with state of the art, high end lasers being capable of producing pulses around 30 fs. However, many experiments require pulses around 10 fs or shorter. Femtosecond pulses are typically generated using spectral broadening via self-phase modulation, followed by dispersion compensation. The most common spectral broadening technique exploits the nonlinear …
Simple Measurement For Ultrafast Field Reconstruction, Chathurangani Jayalath Arachchige
Simple Measurement For Ultrafast Field Reconstruction, Chathurangani Jayalath Arachchige
Electronic Theses and Dissertations
Ultrashort pulses are important for resolving electron motion in semiconductors to measure electronic transport properties. Electron wave packet motion is on the order of attoseconds, requiring temporal resolution on this time scale. However, a major constraint on femtosecond (1 fs = 10−15 s) and attosecond (1 as = 10−18 s) science is how well we can control and compress the excitation and measurement pulses in pump-probe experiments. Such ultrashort pulses require a broad spectrum with careful phase control across its bandwidth to minimize the duration. We discuss a new optical measurement technique that can directly measure the electric field that …
Optimization Of An Ultrasonic Non-Destructive Evaluation Technique For Laser Brazing, Dimitri Shinas
Optimization Of An Ultrasonic Non-Destructive Evaluation Technique For Laser Brazing, Dimitri Shinas
Electronic Theses and Dissertations
Brazing joins two sheets along a seam using a filler metal. In the brazing process, the filler metal is heated, along with the parts to be joined, to a temperature above the melting temperature of the filler material. This allows the filler metal to wet the surfaces of the parts to be joined through capillary action, resulting in the formation of metallic bonds, ultimately forming the joint.
Brazing, like all joining methods, is also susceptible to process variations. These process variations can include wear of the laser, plate misalignment, and external temperature changes. If left unchecked, such variations can eventually …
Variational Energies For The Rydberg P States Of Helium, Cody Mcleod
Variational Energies For The Rydberg P States Of Helium, Cody Mcleod
Electronic Theses and Dissertations
The aim of this work is to solve the quantum mechanical three-body problem for helium, and to obtain high precision eigenvalues for the higher-lying Rydberg states where previous methods have been of limited accuracy. A variational method in correlated Hylleraas coordinates is used involving three distinct distance scales, called a triple basis set. The eigenvalues and matrix elements of other operators are computed for P states of helium up to n = 15 using the varational method with a triple basis set in Hylleraas coordinates. The construction of the wave functions, as well as the behaviour of the asymptotic, intermediate …