Effect Of Dissolved Salts On The Physiochemical Properties Of Deep Eutectic Solvents, 2019 South Dakota State University
Effect Of Dissolved Salts On The Physiochemical Properties Of Deep Eutectic Solvents, Eleanor Haeska, Megan Radtke
The Journal of Undergraduate Research
Green chemistry seeks to make chemical procedures safer, improve reaction efficiency, and utilize environmentally safe reagents. Deep eutectic solvents (DES) have recently become of great interest due to their eco-friendly nature and functionality as solvent for various chemical processes. One key characteristic of DES is their conductive nature and depressed melting point. This project sought to determine the effect of the addition of aqueous solutions of halides on the conductivity of two selected types of DES. Also assessed were the polarity and viscosity of the DES. It can be concluded that aqueous halides had no measureable effect on the conductivity ...
Conformational Dependence Of Σ-Electron Delocalization In The Catenae Xnme2n+2, X = Si, Ge, Sn, And Pb, 2019 University of Colorado at Boulder
Conformational Dependence Of Σ-Electron Delocalization In The Catenae Xnme2n+2, X = Si, Ge, Sn, And Pb, Milena Jovanovic
Chemistry Graduate Theses & Dissertations
Bonds of σ type are the most common chemical bonds, dominating bonding in all molecules and defining the framework of a molecule. It has been long known that electrons in σ bonds can delocalize throughout a molecule. However, the nature of σ-electron delocalization is not fully understood due to its complexity. One of the important aspects of σ-electron delocalization is its conformational dependence, first noted in oligosilanes where properties of a molecule change drastically when it changes conformation. This dissertation describes efforts to understand the conformational dependence of σ delocalization in oligosilanes and their heavier analogs using simple intuitive models ...
Photoinduced Hole Transfer And Recombination Dynamics Of A Cds Quantum Dot Sensitized Mononuclear Water Oxidation Catalyst, 2019 University of Colorado at Boulder
Photoinduced Hole Transfer And Recombination Dynamics Of A Cds Quantum Dot Sensitized Mononuclear Water Oxidation Catalyst, Orion Magruder Pearce
Chemistry & Biochemistry Graduate Theses & Dissertations (1986-2018)
Artificial photosynthesis represents a promising strategy to capture and store solar energy through the production of carbon neutral fuels. This process begins with absorption of a photon by a semiconductor creating an electron-hole pair which are then separated and used to drive reduction and oxidation reactions. CdS nanostructures are model light absorbers for studying these charge transfer reactions and have already demonstrated photoinduced electron transfer to drive a variety of reactions. However, there has been comparatively little progress in understanding how CdS nanostructures may be used to sensitize oxidation reactions such as water oxidation. To this end, we undertook a ...
Reaction Mechanism Between Small-Sized Ce Clusters And Water Molecules: An Ab Initio Investigation On CeN+H2O, 2019 Hefei University of Technology
Reaction Mechanism Between Small-Sized Ce Clusters And Water Molecules: An Ab Initio Investigation On CeN+H2O, Rulong Zhou, Yang Yang, Seema Pande, Bingyan Qu, Dongdong Li, Xiao Cheng Zeng
Xiao Cheng Zeng Publications
Reactions of small-sized cerium clusters Cen (n = 1–3) with a single water molecule are systematically investigated theoretically. The ground state structures of the Cen/H2O complex and the reaction pathways between Cen + H2O are predicted. Our results show the size-dependent reactivity of small-sized Ce clusters. The calculated reaction energies and reaction barriers indicate that the reactivity between Cen and water becomes higher with increasing cluster size. The predicted reaction pathways show that the single Ce atom and the Ce2 and Ce3 clusters can all easily react with H2 ...
Roaming Transition States And Highly Accurate Thermochemistry: A Pepico Study Of Two Small Combustion Systems, 2019 University of the Pacific
Roaming Transition States And Highly Accurate Thermochemistry: A Pepico Study Of Two Small Combustion Systems, Kyle John Covert
University of the Pacific Theses and Dissertations
Two small combustion systems, methyl hydroperoxide (CH3OOH) and 2-propanol ((CH3)2CHOH), were studied using imaging photoelectron photoion coincidence spectroscopy (iPEPICO), which combines photoelectron spectroscopy and photoionization mass spectrometry to detect coincident photoelectron-photoion pairs. In the photon energy range of 11.4–14.0 eV, energy selected CH3OOH+ ions dissociate into CH2OOH+, HCO+, CH3+, and H3O+ ions. The lowest-energy dissociation channel is the formation of the cation of the smallest “QOOH” radical, CH2OOH+. A statistical rate model fitted to the experimental data yields a 0 K appearance energy ...
Refinement Of Production Grade Biodiesel, 2019 GCSU
Refinement Of Production Grade Biodiesel, Campbell Axt, Robert B. Hughley Jr., Sydney Ninneman, Jillian Turner
The modified Burton method for the thermal hydrogen-cracking of peanut oil has been investigated in McGill Research Group since 2009. The successful and reliable production of biodiesel has been achieved since 2014. A hydrocarbon with a viscosity similar to Production Grade Diesel will work in modern diesel engines. The current product has a viscosity significantly lower than production grade diesel. The starting material has a viscosity significantly higher than Production Grade Diesel. Current research is investigating methodologies to mix starting material and product to achieve target viscosity.
Atlas Of Experimental And Theoretical High Temperature Methane Cross Sections From T = 295 To 1000k In The Near-Infrared, 2019 Old Dominion University
Atlas Of Experimental And Theoretical High Temperature Methane Cross Sections From T = 295 To 1000k In The Near-Infrared, Andy Wong, Peter F. Bernath, Michael Rey, Andrei V. Nikitin, Vladimir G. Tyuterev
Chemistry & Biochemistry Faculty Publications
Spectra of hot methane were recorded using a tube furnace and a high-resolution Fourier transform spectrometer. We obtained experimental absorption spectra in the 1.85-1.11 μm near-infrared region at eight temperatures ranging from 295 K up to 1000 K. We have converted these into an atlas of absorption cross sections at each temperature for the methane tetradecad, icosad and triacontad polyads, excluding some spectral intervals either strongly contaminated by water or due to baseline fringes. On the theoretical side, the spectra were simulated from the ab initio-based Reims-Tomsk TheoReTS line list for the same experimental conditions. This line list ...
Recent Trends In Stratospheric Chlorine From Very Short‐Lived Substances, 2019 Old Dominion University
Recent Trends In Stratospheric Chlorine From Very Short‐Lived Substances, Ryan Hossaini, Elliot Atlas, Sandip S. Dhomse, Martyn P. Chipperfield, Peter F. Bernath, Anton M. Fernando, Jens Mühle, Amber A. Leeson, Stephen A. Montzka, Wuhu Feng
Chemistry & Biochemistry Faculty Publications
Very short‐lived substances (VSLS), including dichloromethane (CH2Cl2), chloroform (CHCl3), perchloroethylene (C2Cl4), and 1,2‐dichloroethane (C2H4Cl2), are a stratospheric chlorine source and therefore contribute to ozone depletion. We quantify stratospheric chlorine trends from these VSLS (VSLCltot) using a chemical transport model and atmospheric measurements, including novel high‐altitude aircraft data from the NASA VIRGAS (2015) and POSIDON (2016) missions. We estimate VSLCltot increased from 69 (±14) parts per trillion (ppt) Cl in 2000 to 111 (±22) ppt Cl in 2017, with >80% delivered to the ...
High Level Thermochemical And Spectroscopic Computations For Molecules Relevant To Combustion And The Atmosphere, 2019 Missouri University of Science and Technology
High Level Thermochemical And Spectroscopic Computations For Molecules Relevant To Combustion And The Atmosphere, Bradley K. Welch
"Computational thermochemistry can be a complicated multistep process, but in recent years has become an equal partner with experiment. Many important molecules in combustion systems or in the atmosphere (such as short-lived radicals) are difficult to study experimentally. Predicting highly accurate thermochemistry is a key aspect in understanding these species. In this project, computational thermochemistry was developed into an automated streamlined procedure and then used to understand the methyl and ethyl peroxy families of radicals. This effort involved optimizing a standard workflow for computational thermochemistry. Computational thermochemistry generally requires numerous individual calculations whose cost and scalings vary widely. Conducting such ...
A Hydrogen-Bond Stabilized Mechanism Of Oxygen Evolution In Photosystem Ii: A Proposed Computational Experiment, 2019 University of Montana, Missoula
A Hydrogen-Bond Stabilized Mechanism Of Oxygen Evolution In Photosystem Ii: A Proposed Computational Experiment, Christopher King
Undergraduate Theses and Professional Papers
The ability of plants to take in water and release oxygen into the atmosphere is crucial to the survival of life on Earth. During photosynthesis, water is oxidized to O2 (dioxygen) at the Oxygen Evolving Complex (OEC) of Photosystem II. Structurally, the OEC resembles a box with an open lid, consisting of metal atoms (four manganese and one calcium) bridged by oxygen atoms. The mechanism of action of this complex, however, is not well understood. Various mechanisms have been proposed in recent years to explain how the OEC oxidizes water to dioxygen, but all of these mechanisms contain gaps ...
Multiscale Simulations Of Intrinsically Disordered Proteins, 2019 University of Massachusetts Amherst
Multiscale Simulations Of Intrinsically Disordered Proteins, Xiaorong Liu
Intrinsically disordered proteins (IDPs) lack stable secondary and/or tertiary structures under physiological conditions. The have now been recognized to play important roles in numerous biological processes, particularly cellular signaling and regulation. Mutation of IDPs are frequently associated with human diseases, such as cancers and neuron degenerative diseases. Therefore, it is important to understand the structure, dynamics, and interactions of IDPs, so as to establish the mechanistic basis of how intrinsic disorder mediates versatile functions and how such mechanisms may fail in human diseases. However, the heterogeneous structural ensembles of IDPs are not amenable to high resolution characterization solely through ...
Simulating Hydrogen Bonded Clusters And Zeolite Clusters For Renewable Energy Applications, 2019 University of Massachusetts Amherst
Simulating Hydrogen Bonded Clusters And Zeolite Clusters For Renewable Energy Applications, Qinfang Sun
Our research attention is focused on the development of new fuel cell membrane materials and new zeolites which improve biomass conversion rate to meet the increasing demand of renewable and sustainable energy. We have simulated the dynamics of amphiprotic groups (pyrazole, imidazole, 1,2,3-triazole, 1,2,4-triazole, and tetrazole, acetic acid, formic acid, sulfuric acid, and phosphoric acid) as neat liquids and tethered via linkers to aliphatic backbones, to determine how tethering and varying functional groups affect hydrogen bond networks and reorientation dynamics, both factors thought to influence proton conduction. We used the DL_Poly_2 molecular dynamics code with the ...
Modification Of 2d Materials Utilizing Functional Polymer Interfacial Layers, 2019 University of Massachusetts Amherst
Modification Of 2d Materials Utilizing Functional Polymer Interfacial Layers, Ryan Selhorst
This dissertation describes the modification of 2D transition metal dichalcogenides (TMDCs). These materials exhibit unique electronic properties, ranging from metallic to insulating, and can transport either electrons (n-type) or holes (p-type). Polymers containing electronically-active moieties offer a path to control the electronic properties of a 2D material without altering the inherent structure of the semiconductor. This dissertation focuses on the synthesis of polymers bearing chalcogen-rich or zwitterionic moieties to alter the electronic and solution properties of 2D materials.
Chapter 2 describes polymers containing sulfur-rich tetrathiafulvalene (TTF) and their effects as electroactive coatings on the TMDC molybdenum disulfide (MoS2). These ...
Metal Nanoparticle Synthesis By Photochemical Reduction With A High-Intensity Focused Laser Beam, 2019 Virginia Commonwealth University
Metal Nanoparticle Synthesis By Photochemical Reduction With A High-Intensity Focused Laser Beam, Victoria K. Meader
Theses and Dissertations
Colloidal, metallic nanoparticles have myriad applications, but they are most ideal when they are monodisperse, and demonstrate maximum catalytic utility when they are small (< 5 nm) and uncoated; because their surface area is accessible and maximized. Laser- assisted metal nanoparticle synthesis is a ‘green’ method that has become a topic of active research because it is able to produce uncoated or ‘naked’ products. The nanoparticles synthesized in this work were formed through the reduction of metal salts in aqueous solutions; but the reducing agent is an electron-dense microplasma generated by the laser pulse interacting with the media. Because no chemical reducing agents or stabilizers are needed, the products have no surfactants.
The underlying reaction mechanisms that drive this type of synthesis are generally understood, however, there is insufficient detail that would allow control over the formation of ultimate product morphologies and size distributions. The metals examined in this thesis are: gold, whose formation follows an autocatalytic rate law; and silver, whose formation follows a first-order rate law. Through my research, I was able to explore ...
Experimental And Modeling Investigation Of The Oh-Initiated Oxidation Of Semi-Solid And Aqueous Saccharide Aerosols, 2019 West Virginia University
Experimental And Modeling Investigation Of The Oh-Initiated Oxidation Of Semi-Solid And Aqueous Saccharide Aerosols, Hanyu Fan
Graduate Theses, Dissertations, and Problem Reports
My research focuses on investigating the impact of moisture-induced and oligomer-induced viscosity changes on OH-initiated oxidation of semi-solid aerosols,and the role of gas-liquid interfaces in regulating aqueous aerosol chemistry. Saccharides, which are a major constituent of aqueous atmospheric aerosols, are chosen as model molecules to form highly oxygenated organic aerosols. The experiments are performed using an atmospheric pressure flow-tube reactor with both online VUV-AMS (Vacuum-Ultraviolet Aerosol Mass Spectrometer) and offline GC-MS analysis techniques. The decay rates of saccharide are determined by measuring the loss signal of saccharide in the particle phase as a function of OH exposure (time-integrated total ...
Exomol Line List - Xxxiv. A Rovibrational Line List For Phosphinidene (Ph) In Its X³Σ¯ And A¹Δ Electronic States, 2019 Old Dominion University
Exomol Line List - Xxxiv. A Rovibrational Line List For Phosphinidene (Ph) In Its X³Σ¯ And A¹Δ Electronic States, Jonathan Langleben, Jonathan Tennyson, Sergei N. Yurchenko, Peter Bernath
Chemistry & Biochemistry Faculty Publications
A rovibronic line list for the ground (X3Σ−) and first excited (a1Δ) states of phosphinidene, 31PH, is computed. The line list is designed for studies of exoplanetary and cool stellar atmospheres with temperatures up to 4000 K. A combination of empirical and ab initio data is used to produce the line list: potential energy curves (PECs) are fitted using experimental transition frequencies; these transitions are reproduced with a root mean square error of 0.01 cm−1. The nuclear Schrödinger equation is solved using these PECs plus Born–Oppenheimer and spin splitting correction terms. Line ...
Au60–: The Smallest Gold Cluster With The High-Symmetry Icosahedral Core Au13, 2019 University of Nebraska - Lincoln
Au60–: The Smallest Gold Cluster With The High-Symmetry Icosahedral Core Au13, Seema Pande, Xingao Gong, Lai-Sheng Wang, Xiao Cheng Zeng
Xiao Cheng Zeng Publications
Among coinage metal nanoclusters with 55 atoms, only Ag55– and Cu55– are the geometric magic-number clusters, as both exhibit icosahedral symmetry. Au55–, however, exhibits much lower symmetry due largely to the strong relativistic bonding effect. In this study, we collect a much larger population (>10,000 isomers) of low-energy isomers of Au55– to Au60– by using the combined density-functional theory and basin-hopping global optimization method. We also include the spin−orbit effect in the density-functional theory computation to achieve simulated photoelectron spectra in quantitative fashion. Remarkably, we uncover that the Au13 core with the ...
Call For Abstracts - Resrb 2019, July 8-9, Wrocław, Poland, 2018 Wojciech Budzianowski Consulting Services
Call For Abstracts - Resrb 2019, July 8-9, Wrocław, Poland, Wojciech M. Budzianowski
No abstract provided.
Optimization Of Useful Hard X-Ray Photochemistry, 2018 University of Nevada, Las Vegas
Optimization Of Useful Hard X-Ray Photochemistry, David Lewis Goldberger
UNLV Theses, Dissertations, Professional Papers, and Capstones
X-ray induced damage is generally considered a nuisance, but in the field of Useful Hard X-ray Photochemistry we harness the highly ionizing and penetrating properties of hard X-rays (> 7 keV) to initiate novel photochemical decomposition and synthesis at ambient and extreme conditions. Preliminary experiments suggest that the energy of irradiating photons and the sample pressure play roles in determining the nature of X-ray induced damage. Here, we present the X-ray energy dependence of damage induced in strontium oxalate, strontium nitrate, and barium nitrate, as well as the pressure dependence of X-ray induced damage of strontium oxalate. Our results indicate that ...
Photophysical Characterization And Wavelength Tuning Of Natural And Synthetic Oxobacteriochlorins And Biohybrids, 2018 Washington University in St. Louis
Photophysical Characterization And Wavelength Tuning Of Natural And Synthetic Oxobacteriochlorins And Biohybrids, Don Hood
Arts & Sciences Electronic Theses and Dissertations
ABSTRACT OF THE DISSERTATION
Photophysical Characterization and Wavelength Tuning of Natural and Synthetic Oxobacteriochlorins and Biohybrids
Donald L. Hood
Doctor of Philosophy in Chemistry
Washington University in St. Louis, 2018
Dr. Dewey Holten, Chairperson
Herein is discussed the theoretical and practical unpinnings of photophysical behaviors and kinetic constants for tetrapyrrole macrocycles, to wit, porphyrins, chlorins, and bacteriochlorins. Understanding the characteristic photophysical response of tetrapyrroles to changes in environment or substituents is important to designing synthetic chromophores with tunable absorption wavelengths and for preparing useful biohybrids of natural photosynthetic light antennas combined with unnatural chromophores attached to the light antenna ...