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Full-Text Articles in Chemistry

Impact Of Chemical Doping On The Thermoelectric Charge Transport Of Organic Semiconductors, Connor J. Boyle Nov 2018

Impact Of Chemical Doping On The Thermoelectric Charge Transport Of Organic Semiconductors, Connor J. Boyle

Doctoral Dissertations

The thermoelectric properties of organic semiconductors allow them to directly convert heat into electricity without the use of moving parts and to directly convert electricity into heat without the use of working fluids. These properties offer opportunities for the generation of electricity from non-conventional or renewable sources of heat and for refrigeration without the risk of leaking harmful working fluids at any length scale down to the nanoscale. Since organic materials are lightweight, flexible, and made from abundant resources, these opportunities could one day become affordable for widespread use and could be expanded to include specialized and otherwise difficult to …


Voltage-Driven Polyelectrolyte Complexation Inside A Nanopore, Prabhat Tripathi Oct 2018

Voltage-Driven Polyelectrolyte Complexation Inside A Nanopore, Prabhat Tripathi

Doctoral Dissertations

This thesis investigates how a pair of oppositely charged macromolecules can be driven by an electric field to form a polyelectrolyte complex inside a nanopore. To observe and isolate an individual complex pair, a model protein nanopore, embedded in artificial phospholipid membrane, allowing compartmentalization (cis/trans) is employed. A polyanion in the cis and a polycation in the trans compartments are subjected to electrophoretic capture by the pore. We find that the measured ionic current across the pore has a distinguishable signature of complex formation, which is different from the signature of the passage of individual molecules …


The Balance Between Dipole-Dipole Interactions And Steric Exclusion On Ordering In Cationic Polymers, Chinomso Nwosu Oct 2018

The Balance Between Dipole-Dipole Interactions And Steric Exclusion On Ordering In Cationic Polymers, Chinomso Nwosu

Doctoral Dissertations

Structure-property correlations in charged polymers is an interesting facet of polymer science. Understanding the effects of intermolecular forces on the morphologies of polymers can lead to the design of membranes with desired structures to improve properties, for example ion conductivity. In random, comb-shaped polycations, competing intermolecular forces result in two different short-range orderings. Side-chain steric repulsion results in backbone-backbone morphology characterized by periodic spacing between polymer backbones. However, dipole - dipole attraction in these polycations can facilitate the formation of ionomer cluster morphology characterized by a spacing between clustered dipoles. Although both of these short-range orderings have disparate origins, their …


The Dissociative Chemisorption Of Methane And Its Isotopologues On Metal Surfaces, Han Guo Oct 2018

The Dissociative Chemisorption Of Methane And Its Isotopologues On Metal Surfaces, Han Guo

Doctoral Dissertations

The dissociative chemisorption of small molecules on metal surfaces is an important step in many heterogeneous catalytic processes, and has received considerable scientific attention. In this thesis, a quantum approach based on the reaction path Hamiltonian is used to explore the dissociative chemisorption of methane and its deuterated isotopologues on several metal surfaces. The theoretical approach is described in Chapter 2. This approach treats all 15 degrees of freedom of the methane molecule, and includes the effects of lattice motion, allowing us to examine the translational and vibrational enhancements, mode- and bond-selectivity and the surface temperature dependence observed in experiments. …


Combined Spectroscopic And Scanning Probe Studies Of Electronic Interactions In Nanostructured 1d And 2d Semiconductors, Peijian Wang Jul 2018

Combined Spectroscopic And Scanning Probe Studies Of Electronic Interactions In Nanostructured 1d And 2d Semiconductors, Peijian Wang

Doctoral Dissertations

This dissertation includes the exploration about the following research questions: 1. What is the correlation between the work function and ground state interactions in organic semiconductor assemblies? 2. How do non-covalent chemical doping tune the work function in MoS2? 3. Are there surface charges in the Aluminum doped ZnO nanocrystals (AZO) and what's the evolution of the surface charges and polarizabilities from undoped AZO to doped AZO? 4. How is the homogeneity like during doping in the organic thermoelectric materials? The techniques we employed in the research is the spatially registered Kelvin Probe Force Microscopy and Photoluminescence spectroscopy …


Photofragment Imaging Fast Ion Beams, Michael D. Johnston Jr. Jul 2018

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 …


Spectroscopic Studies Of Gas-Phase Metal Cation Complexes With Alkanes And Ammonia, Muhammad Affawn Ashraf Mar 2018

Spectroscopic Studies Of Gas-Phase Metal Cation Complexes With Alkanes And Ammonia, Muhammad Affawn Ashraf

Doctoral Dissertations

Understanding the non-covalent interaction between metals and small ligands such as methane and ammonia is of key importance because of their industrial and biological applications. However, these interactions are difficult to study and quantify in the bulk phase due to the interaction with neighboring molecules or atoms. Gas phase spectroscopy of mass-selected clusters is a powerful technique that overcomes this challenge by allowing clusters with known composition to be studied in the gas phase. In this thesis, we investigate the interaction between three types of small molecular ligands with metal and metal cluster ions, and answer questions about their geometries …