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Full-Text Articles in Physical Sciences and Mathematics
Determining Bond Strengths And Dissociation Dynamics Of Diatomic Metal-Containing Ions By Photofragment Imaging, Schuyler P. Lockwood
Determining Bond Strengths And Dissociation Dynamics Of Diatomic Metal-Containing Ions By Photofragment Imaging, Schuyler P. Lockwood
Doctoral Dissertations
Studies of simple metal ion – ligand complexes have primarily focused on understanding their roles in activating C-H and C-C bonds. However, data are often lacking on the fundamental properties of these species, which can have unusual bond orders and cluttered electronic structures with many states of multi-reference character, complicating their treatment in theoretical studies. Experimental work determining high-precision bond energies, ground state identities and excited state dynamics of a wider variety of metal-containing ions is needed to establish a robust set of well-characterized benchmark molecules. This work describes studies of the energetics and dynamics of several MX+ species, …
Driving Piezochromism And Metallicity In Van Der Waals Materials Under Compression, Nathan Harms
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 …
The Exploration Of Small Molecules, Lanthanide Complexes, And Catalysis Using Electronic Structure Theory, Dynamics, And Machine Learning, Gavin Mccarver
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 …
Development And Demonstration Of Sampling Techniques For A Chirped Pulse Fourier Transform Microwave Spectrometer, Frank Edward Marshall
Development And Demonstration Of Sampling Techniques For A Chirped Pulse Fourier Transform Microwave Spectrometer, Frank Edward Marshall
Doctoral Dissertations
"With the introduction of the Chirped Pulse-Fourier Transform Microwave Spectrometer in the past decade, it has become possible to rapidly study the rotational spectra of molecules in the gas phase. It is possible to study molecules that are not normally in the gas phase through the use of various sourcing techniques. The development of both the heated nozzle and the laser ablation sourcing techniques allow for the study of liquids and solids, respectively. The design and performance of these sources will be presented in detail and discussed. Additionally, the development of a Multi-Antennae detection scheme, useful in improving overall sensitivity …
Photofragment Imaging Fast Ion Beams, Michael D. Johnston Jr.
Photofragment Imaging Fast Ion Beams, Michael D. Johnston Jr.
Doctoral Dissertations
Metal-containing ions have been the subject of much research due to their roles in catalytic activation and small cluster chemistries. However, they can be difficult to study both experimentally and theoretically, and new approaches are needed. The goal of the research described here is to characterize the electronic structures and thermodynamics of metal-containing ions using gas-phase spectroscopy experiments performed on a powerful new instrument. Presented in the following chapters are the details of a recently built velocity map imaging mass spectrometer that is capable of imaging the photofragments of trap-cooled (≥7K) ions produced in a versatile ion source. This instrument …
Mining Uranium From Seawater: A Coordination Chemistry Approach, Nada Mehio
Mining Uranium From Seawater: A Coordination Chemistry Approach, Nada Mehio
Doctoral Dissertations
Poly(acrylamidoxime) fibers are the current state-of-the-art adsorbent for mining uranium from seawater. However, the amidoxime group is not perfectly selective towards the uranyl cation, in particular, competition with transition metal cations remains a major challenge. In order for subsequent generations of chelating polymer adsorbents to be improved, the coordination chemistry of amidoxime-uranyl and -transition metal cation complexes needs to be better understood. While the coordination mode of amidoxime-uranyl complexes has been established in the literature, a number of amidoxime-transition metal cation complex binding motifs can be observed on the Cambridge Structrural Database. Likewise, the formation constants, or log K values, …