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Full-Text Articles in Physical Sciences and Mathematics

Light Matter Interactions: A Study Of Soft Materials Using Linear And Nonlinear Spectroscopy, Muhammad Redwan Hassan Dec 2022

Light Matter Interactions: A Study Of Soft Materials Using Linear And Nonlinear Spectroscopy, Muhammad Redwan Hassan

Doctoral Dissertations

The adoption of complex fluids for various industrial applications is becoming normal. Complex fluids offer tunability, wide range solubility, and chemical and thermal stability which are the factors that conventional polar and non-polar solvents often lack. However, fundamental studies of these fluid systems are still lacking which is limiting the appropriate use of these complex fluids in many applications. The goal of this dissertation was to study and characterize complex fluids for application in electrolytes for redox flow batteries. Chapter 3 and chapter 4 feature the study of microemulsions and deep eutectic solvents (DES) by fluorescence techniques. Fluorescence studies of …


Frontiers In The Self-Assembly Of Charged Macromolecules, Khatcher O. Margossian Oct 2022

Frontiers In The Self-Assembly Of Charged Macromolecules, Khatcher O. Margossian

Doctoral Dissertations

The self-assembly of charged macromolecules forms the basis of all life on earth. From the synthesis and replication of nucleic acids, to the association of DNA to chromatin, to the targeting of RNA to various cellular compartments, to the astonishingly consistent folding of proteins, all life depends on the physics of the organization and dynamics of charged polymers. In this dissertation, I address several of the newest challenges in the assembly of these types of materials. First, I describe the exciting new physics of the complexation between polyzwitterions and polyelectrolytes. These materials open new questions and possibilities within the context …


Driving Piezochromism And Metallicity In Van Der Waals Materials Under Compression, Nathan Harms Aug 2022

Driving Piezochromism And Metallicity In Van Der Waals Materials Under Compression, Nathan Harms

Doctoral Dissertations

Complex chalcogenides provide an important platform to explore the interplay between structure, charge, and spin across pressure-induced phase transitions. Where much of the previous research has been focused on tuning these materials towards the single-layer limit, we instead explore the modification of bond lengths and bond angles under compression. In the first project we revealed piezochromism in MnPS3. We combined high pressure optical spectroscopy and first-principles calculations to analyze the dramatic color change (green → yellow → red → black) that takes place as the charge gap shifts across the visible and into the near infrared region, moving …


Molecular Vibrations And Shape-Selectivity: A Computational Model Of Biofuel Precursors In Zeolites, Babgen Manookian Jun 2022

Molecular Vibrations And Shape-Selectivity: A Computational Model Of Biofuel Precursors In Zeolites, Babgen Manookian

Doctoral Dissertations

We have used Density Functional Theory (DFT) to model acyclic and cyclic olefins in acidic zeolites. We have studied the impact of host-guest interactions between adsorbed molecules and zeolite frameworks through the lens of molecular vibrations and shape-selectivity. This work considered three zeolite frameworks with varying pore structures and environments: large pore zeolite HMOR and medium pore zeolites HZSM-5 and HZSM-22. A key finding is that for acyclic olefins in acidic zeolites there exists two regimes of host-guest interaction: a strong interaction leading to protonation and a weak interaction between charged guest and zeolite framework. We found that these interactions …


The Exploration Of Small Molecules, Lanthanide Complexes, And Catalysis Using Electronic Structure Theory, Dynamics, And Machine Learning, Gavin Mccarver May 2022

The Exploration Of Small Molecules, Lanthanide Complexes, And Catalysis Using Electronic Structure Theory, Dynamics, And Machine Learning, Gavin Mccarver

Doctoral Dissertations

With the ever increasing availability of computational resources, more challenging chemical systems can be studied. Among these challenges are the rotational and vibrational spectra of diatomic molecules within spectroscopic accuracy, the environmental perturbations induced on a rotating water molecule, the prediction of free binding energies of lanthanide complexes using machine learning, and the study of catalytic mechanisms through a theoretical framework. High levels of electronic structure theory were combined with a rigorous treatment of either the anharmonic vibrational wave functions to study diatomic molecules or the rotational wave functions to study H2O-pH2 interactions. The former was initially …


Experimental Physical Chemistry Applications For Material Science: The Neutron Vibrational Spectrum Of Biaxially-Oriented Pet And Hkust-1 As A Qcm-Based Ethylene Sensor, Zachary D. Stroupe May 2022

Experimental Physical Chemistry Applications For Material Science: The Neutron Vibrational Spectrum Of Biaxially-Oriented Pet And Hkust-1 As A Qcm-Based Ethylene Sensor, Zachary D. Stroupe

Doctoral Dissertations

This work is divided into two comprehensive subjects exploiting fundamental properties of physical chemistry to understand applied materials. The two subjects will be: the inelastic neutron scattering of thin polyethylene terephthalate (PET) films and the design and development of a quartz crystal microbalance-based ethylene detector. For the work involving the thin films, the inelastic neutron scattering (INS) was accomplished using the high flux of the VISION vibrational spectrometer at the Spallation Neutron Source yielding the highest quality data currently available. The torsional vibrational modes of biaxially-oriented PET (bPET) will be reported with the help of DFT calculations to aid in …