Materials Science

With wide applications ranging from quantum communication and metrology to biomedicine, single photon sources in solid-state hosts have become a major area of study. Here, we focus on three applications: nanothermometry, optically detected magnetic resonance (ODMR), and second order autocorrelation. We present novel statistical and machine learning (ML) approaches to extract information from experimental and simulated data and benchmark these methods against traditional inference-based statistical approaches. We found that compared to traditional inference-based methods ML algorithms can: i) predict temperatures at the nanoscale with greater accuracy and with less calibration points than traditional fitting methods; ii) identify the resonance peaks in ODMR spectra with factors ~1.3x and ~4.7x better accuracy and resolution and achieved equal or better performance with ~5x less data; and iii) have the potential to parse second order autocorrelation data more efficiently. ML algorithms are thus powerful tools for quantum sensing techniques.

Author Keywords: colour centers, machine learning, nanosensing, nanothermometry, optically detected magnetic resonance, second order autocorrelation

Coherent anti-Stokes Raman scattering (CARS) microscopy is a label-free chemical imaging modality that uses CARS as a contrast mechanism to spatially resolve materials based on their molecular vibrational spectra. Due to the presence of a non resonant background that obfuscates the chemical information contained in CARS spectra, CARS images suffer from poor contrast and cannot be readily used for quantitative chemical analysis. Over the past two decades, spectral retrieval methods have been developed to obtain Raman-like spectra from CARS spectra. These methods promise to improve image contrast and enable reliable quantitative analysis. In this work I systematically evaluate a selection of the forefront spectral retrieval methods, including both analytical and machine learning approaches, to determine how well they perform at the task of non resonant background removal. The more recent machine learning methods demonstrate remarkable performance on spectra resembling the training dataset but are not as suitable as the analytical methods in general. The analytical methods based on the discrete Hilbert transform thus remain preferable due to their ease-of-use and general applicability.

Author Keywords: chemical imaging, coherent anti-stokes raman scattering, kramers-kronig analysis, machine learning, non-resonant background, spectral phase retrieval

This thesis comprises two parts:Part I describes a method to improve the accuracy with which the polarization state of light can be characterized by the rotating quarter-wave plate technique. Through detailed analysis, verified by experiment, we determine the positions of the optic axes of the retarder and linear polarizer, and the wave plate retardance, to better than 1° for typical signal-to-noise ratios. Accurate determination of the Stokes parameters can be achieved using this technique to determine the precise retardance at each of the wavelengths of interest. In Part II, a theoretical analysis of the Fabry-Perot interferometer and its application to quantitative absorption spectroscopy is presented. Specifically the effects of broadening due to non-monochromatic light sources and examples of non-ideal etalon surfaces on the visibility of absorption features are investigated. The potential of this type of spectrometer for ethanol detection in a portable breath analysis application is discussed.

Author Keywords: ABSORPTION SPECTROSCOPY, CALIBRATION, FABRY-PEROT INTERFEROMETER, OPTICS, POLARIMETRY

The oil sands industry is producing large volumes of tailings waste reaching 2 billion cubic meters by 2034 In this study, the industrial standard flocculant, high molecular weight PAM, was grafted from the surface of activated carbon (AC). This material was designed to increase the flocculant's hydrophobicity and density. Different molecular weight PAM was grafted from AC with different AC contents and particle sizes (AC-PAMs). The AC-PAMs were synthesized by surface-initiated atom transfer radical polymerization (SI-ATRP). The AC-PAMs achieved molecular weights 107 – 5,600 kg/mol and AC content of 0.2 – 5.8% on <0.1 and 0.1 – 0.5 mm AC particle diameters. AC-PAM achieved higher solids contents up to 51 wt% using AC-PAM with 5.1 wt% AC due to the grafting from a hydrophobic AC core. To summarize, our work shows the successful grafting of PAM from AC and its potential as a flocculant for mature fine tailings.

Author Keywords: activate carbon, atom transfer radical polymization, flocculation, grafting-from, polyacrylamide, surface-initiated polymerization

We study a one-dimensional Fermi-Hubbard model with disorder in charge and spin degrees of freedom. We calculate the time dependence of the entanglement entropy. While previous research on disordered interacting systems has typically focused on systems with either charge or spin, our model enables us to explore the interplay between charge and spin in shaping the behavior of entanglement. We use a method that identifies optimally local charge- and spin-specific integrals of motion. We ask how the locality level of these integrals of motion influences the capacity of low-order terms in the l-bit Hamiltonian to capture the entanglement entropy. Our results show that increasing the locality level improves the accuracy of low-order terms in capturing entanglement entropy dynamics. With equally strong charge and spin disorder, the behavior of the entanglement entropy closely resembles that observed in single-degree-of-freedom systems, and the l-bit Hamiltonian truncated at second order accurately captures this behavior.

Author Keywords: Entanglement Entropy, Fermi-Hubbard Model, Hungarian Algorithm, l-bit Hamiltonian, Local Integrals of Motion, Many-Body Localization

Microwave resonances in isolated water-based spheres, dimers, and trimers are explored using simulations conducted with COMSOL Multiphysics. The study centers on morphology-dependent resonances (MDRs) and hotspot characteristics in cm-sized objects at microwave frequencies. Monomers subjected to microwave radiation exhibit four distinct resonant modes at specific sizes characterized by electric and magnetic field distributions which correspond to magnetic-dipolar, electric-dipolar, magnetic quadrupolar, and electric quadrupolar resonances, respectively. Dimer configurations reveal intriguing hotspot features, with axial hotspots emerging as a key resonant characteristic. The three fundamental dimer orientations dictate unique resonant behaviors, highlighting the sensitivity of hotspot intensity to orientation changes, but smooth and consistent trends during transitions between them. Investigations into trimer structures, as a more intricate geometry formed by interconnected dimers, reveal the subtle interactions of spheres in a trimer structure. Trimer hotspots largely reflect the sum of isolated dimer hotspot contributions, showcasing the energy conservation with no evidence of a newly formed hotpot. Our results, while arising as a consequence of the particularly high index of refraction of water at GHz frequencies, are generalizable to other length scales (such as nano-photonics), were materials with sufficiently high refractive index and transparency to be found.

Author Keywords: COMSOL simulations, Electromagnetic physics, Microwave frequencies, Morphology-dependent resonance, water-based objects

This thesis explores the remediation of naphthenic acids (NAs) from oil sands process-affected water (OSPW) using activated carbon (AC) derived from petroleum coke (PC) chemically activated with potassium hydroxide. The research aims to identify the most effective method for the adsorptive removal of NAs by optimizing the use of economically viable KOH quantities and to apply Fourier Transform Ion Cyclotron Resonance Mass Spectrometry (FT-ICR-MS) for species-specific detection and characterization of NAs, crucial for targeting specific NAs in future studies.Prior research focused on single-species adsorption, establishing a foundational understanding of non-competitive adsorption before applying these findings to more complex NA mixtures and OSPW. This study builds upon this foundation, addressing a significant gap in the literature concerning the use of petcoke-derived AC with low KOH ratios and short activation times, which are economically advantageous for large scale applications. In this thesis, a comprehensive investigation into the kinetics and isotherms of NA adsorption on various ACs including PAC (petroleum coke AC), PWAC (pore-widened AC), HAC (heat-treated wood-based AC), and CAC (commercial AC) was conducted. The study specifically examines the adsorption behaviors of seven model NAs, reflecting the diverse molecular structures present in real world OSPW. The research also explores the impact of pore widening techniques on the adsorption efficiency of ACs, hypothesizing that increased mesoporosity enhances the adsorption of NA compounds. The findings demonstrate that FT-ICR-MS is an essential tool for precisely characterizing the NA species in OSPW, revealing that pore-widened ACs significantly improve the adsorption of NAFCs. This thesis contributes to the field of environmental remediation by offering new insights into the optimization of AC for NA removal, emphasizing the importance of surface chemistry and mesoporosity in enhancing adsorption efficiency. The study's outcomes have significant implications for the treatment of OSPW, providing a scalable and cost-effective solution to mitigate the environmental impacts of oil sands production.

Author Keywords: activated carbon, FT-ICR-MS, naphthenic acids, oil sands, petroleum coke, process-affected water

The interplay between electron charge, spin, and ferroelectric polarization is under-explored for conducting ferroelectric domain walls (DWs). DWs are interfaces that separate regions (domains) within a material that have different orientations of spontaneous polarization. We investigated the electronic band structure of t2g electrons, confined to 90° charged do main walls (CDWs) in barium titanate (BaTiO3), a prototypical perovskite ferroelectric. A key novel aspect of our study is the explicit inclusion of both orbital and spin degrees of freedom in the Hamiltonian. This leads to an Ising-type spin-orbit coupling (SOC). We constructed a tight-binding (TB) model for t2g electrons that is constrained by symmetries of the DW, including time-reversal, mirror, and rotational symmetries. First-principles density functional theory (DFT) calculations were performed to extract the TB parame ters. Our findings offer new insights into spin-orbit interactions at ferroelectric domain walls and open avenues for their potential use in next-generation electronic and spintronic devices

N-Heterocyclic Carbenes (NHCs) have significantly impacted organometallic chemistry as ligands in transition metal catalysis, offering strong electron-donating properties and high bond dissociation energies. However, their structural versatility is limited by the scarcity of commercial precursors and challenging modification procedures. Furthermore, we have investigated its coordination to transition metals; copper, silver, and palladium. We further demonstrate the effects of its steric parameters by utilizing the Suzuki-Miyaura cross-coupling of aryl chlorides using [(RO-NHC)Pd(allyl)Cl] as precatalysts. This study demonstrates increased catalyst activity with bulkier ligands in Suzuki-Miyaura cross-coupling reactions. We also present simplified procedures for copper NHC complexes using triethylamine with no requirements for special equipment and techniques. Preliminary investigations towards a more economical approach to measuring the electron donating abilities of NHCs were conducted using CuI and AgI cyanide complexes as probes. The outcomes of this research may contribute to the growing research in the applications of NHCs as ligands in catalysis.

Author Keywords: Catalysis, Ligand synthesis, N-Heterocyclic carbenes, Organic Chemistry, Organometallic Chemistry, Transition metal catalysis

This thesis describes the preparation, optimization, functionalization, and characterization of activated carbon materials sourced from a petroleum coke feedstock for the tailored removal of heavy metal species in contaminated waters. The goal of this work is to develop an understanding of the mechanisms that drive adsorption of heavy metals onto activated carbon surfaces. By determining the mechanisms that drive adsorption, activated carbon materials can be modified to increase the efficiency of the adsorption process. The novelty of this work comes from the use, modification, and functionalization of activated carbon derived from petroleum coke, a waste by-product of the oil-sands extraction process, a source not prevalent in current literature. The novelty also comes from the determination of the methods by which heavy metals are adsorbed onto the given adsorbate as literature does not focus on the mechanisms themselves. The work presented sheds light on the specific adsorption mechanisms, with the aim of elucidating how a given material's surface can be enhanced to target a specific analyte. This work focused on the use of microwave plasma atomic emission spectroscopy (MP-AES), x-ray photoelectron spectroscopy (XPS), and Brunauer-Emmett-Teller theory (BET) to obtain the necessary data required for the determination of adsorption mechanisms, adsorption capacities, and surface characterization of the materials. MP-AES is used for the determination of the adsorption capacity of the materials produced. Surface characterization of the materials was done using XPS, and surface area and pore size distributions were determined using BET for surface area determination and nitrogen adsorption measurements following density functional theory for pore size distribution determination. XPS of the activated carbon post-chromium and post-arsenic adsorption show a reduction of the metals from chromium (VI) to chromium (III) and from arsenic (V) to arsenic (III). By increasing the amount of hydroxyl functional groups on the AC surface through a simple thermal-treatment, the chromium adsorption was increased from 17.0 mg/g to 22.4 mg/g. By loading a reducing agent onto the activated carbon surface, an increased number of potential binding sites for the arsenic are loaded onto the AC surface and the adsorption of arsenic increased from 8.1% to 51%.

Author Keywords: Activated Carbon, Adsorption, Adsorption Mechanisms, Arsenic, Chromium, Petroleum Coke