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Articles 1 - 11 of 11
Full-Text Articles in Entire DC Network
Optical Susceptibilities Of Supported Indium Tin Oxide Thin Films, Jonathan L. Humphrey, Darius Kuciauskas
Optical Susceptibilities Of Supported Indium Tin Oxide Thin Films, Jonathan L. Humphrey, Darius Kuciauskas
Chemistry Publications
The third-order nonlinear optical susceptibility of indium tin oxide (ITO) thin films on glass substrates, χ(3)ITO, was determined in the near-IR spectral region using degenerate four wave mixing (DFWM)spectroscopy with 100fs laser pulses. A DFWM method for measuring thin films on thick substrates was refined for the characterization of films less than 100nm thick and applied to ∼25nm thick ITO films. It was found that χ(3)ITO is purely electronic at 900–1300nm (11000–7700cm−1) and has a value of (2.16±0.18)×10−18m2V−2. Theχ(3)ITO value reaches (3.36±0.28)×10−18m2V−2 at 1500nm (6700cm−1) due to two-photon absorption by free carriers (electrons). Ultrafast electron relaxation was also observed. The …
Reversible Paramagnetism To Ferromagnetism In Transition Metal-Doped Tio2 Nanocrystals Prepared By Microwave Irradiation, Garry Glaspell, Asit B. Panda, M. S. El-Shall
Reversible Paramagnetism To Ferromagnetism In Transition Metal-Doped Tio2 Nanocrystals Prepared By Microwave Irradiation, Garry Glaspell, Asit B. Panda, M. S. El-Shall
Chemistry Publications
TiO2nanoparticlesdoped with 1%, 5%, and 10% M (M=Co, Fe, and Ni) were prepared by microwave irradiation and characterized using x-ray diffraction, transmission electron microscopy, and magnetometry. The as-prepared samples are found to be paramagnetic at room temperature, with the magnetic susceptibility following the Curie-Weiss law in the investigated range of 2–300K. However, transformation from paramagnetism to room-temperature ferromagnetism (RTFM) was observed by hydrogenating the samples at 400°C. Reheating in air converted the samples back to paramagnetic while rehydrogenating the samples again induced ferromagnetism. It is argued that the reversible RTFM observed is due to interaction between the dopant metal ions …
Cation Occupancy Determination In Manganese Zinc Ferrites Using Fourier Transform Infrared Spectroscopy, M. D. Shultz, E. E. Carpenter, S. A. Morrison, S. Calvin
Cation Occupancy Determination In Manganese Zinc Ferrites Using Fourier Transform Infrared Spectroscopy, M. D. Shultz, E. E. Carpenter, S. A. Morrison, S. Calvin
Chemistry Publications
The magnetic and electric properties of ferrites are influenced by the cation distribution within the crystalline spinel lattice. Methods such as extended x-ray-absorption fine structure(EXAFS) have been used to determine cation occupancies within the crystalline structure of materials such as manganesezincferrite (MZFO); however, it is not practical to be used for daily analysis. Fourier transform infrared (FTIR)spectroscopy is another technique which has the potential to determine cation occupancy while offering speed and convenience. In the literature it has been demonstrated that in ferrite systems FTIR data can be correlated to cation percentages when comparing tetrahedral (Td) and octahedral (Oh) sites. …
Orientational Correlations In Liquid Acetone And Dimethyl Sulfoxide: A Comparative Study, Sylvia E. Mclain, Alan K. Soper, Alenka Luzar
Orientational Correlations In Liquid Acetone And Dimethyl Sulfoxide: A Comparative Study, Sylvia E. Mclain, Alan K. Soper, Alenka Luzar
Chemistry Publications
The structure of acetone and dimethyl sulfoxide in the liquid state is investigated using a combination of neutron diffractionmeasurements and empirical potential structure refinement (EPSR) modeling. By extracting the orientational correlations from the EPSR model, the alignment of dipoles in both fluids is identified. At short distances the dipoles or neighboring molecules are found to be in antiparallel configurations, but further out the molecules tend to be aligned predominately as head to tail in the manner of dipolar ordering. The distribution of these orientations in space around a central molecule is strongly influenced by the underlying symmetry of the central …
Magnetic And Mossbauer Spectroscopy Studies Of Nanocrystalline Iron Oxide Aerogels, E. E. Carpenter, J. W. Long, D. R. Rolison, M. S. Logan, K. Pettigrew, R. M. Stroud, L. Theil Kuhn, B. Rosendahl Hasen, S. Mørup
Magnetic And Mossbauer Spectroscopy Studies Of Nanocrystalline Iron Oxide Aerogels, E. E. Carpenter, J. W. Long, D. R. Rolison, M. S. Logan, K. Pettigrew, R. M. Stroud, L. Theil Kuhn, B. Rosendahl Hasen, S. Mørup
Chemistry Publications
A sol-gel synthesis was used to produce iron oxide aerogels. These nanocrystalline aerogels have a pore-solid structure similar to silica aerogels but are composed entirely of iron oxides. Mössbauer experiments and x-ray diffraction showed that the as-prepared aerogel is an amorphous or poorly crystalline iron oxide, which crystallized as a partially oxidized magnetite during heating in argon. After further heat treatment in air, the nanocrystallites are fully converted to maghemite. The particles are superparamagnetic at high temperatures, but the magnetic properties are strongly influenced by magnetic interactions between the particles at lower temperatures.
Chemometric Analysis Of Multivariate Liquid Chromatography Data: Applications In Pharmacokinetics, Metabolomics, And Toxicology, Sarah Elizabeth Graham Porter
Chemometric Analysis Of Multivariate Liquid Chromatography Data: Applications In Pharmacokinetics, Metabolomics, And Toxicology, Sarah Elizabeth Graham Porter
Theses and Dissertations
In the first part of this work, LC-MS data were used to calculate the in-vitro intrinsic clearances (CLint) for the metabolism of p-methoxyrnethamphetamine (PMMA) and fluoxetine by the CYP2D6 enzyme using a steady-state (SS) approach and a new general enzyme (GE) screening method. For PMMA, the SS experiment resulted in a CLint of 2.7 ± 0.2 µL pmol 2D6-1min-1 and the GE experiment resulted in a CLint of 3.0 ± 0.6 µL pmol 2D6-1min-1. For fluoxetine, the SS experiment resulted in a CLint of 0.33 ± 0.17 µL pmol 2D6-1min-1 and the GE experiment resulted in a CLint of 0.188 …
Synthesis Of Novel Antimycobacterials And A Fluorescent Sensor For Simple Carbohydrates, Brian Thomas Walker
Synthesis Of Novel Antimycobacterials And A Fluorescent Sensor For Simple Carbohydrates, Brian Thomas Walker
Theses and Dissertations
Cell surface carbohydrates play an important role in a wide variety of biological processes such as inflammation, tumor metastasis, and viral and bacterial infection. The goal of our research has been two-fold. The first objective was the synthesis of antimycobacterial compounds. A mannose containing tetrasaccharide from the mannan core of lipoarabinomannan (LAM) of Mycobacterium tuberculosis has been synthesized using α-D-methylmannopyranoside as starting material and Koeings-Knorr reactions to couple saccharides. The synthesis was completed in nine steps and in 14% total yield. This compound should be useful in competitive inhibition studies with macrophages or as an immunological marker. We have successfully …
Quantitative Model For The Prediction Of Hydrodynamic Size Of Nonionic Reverse Micelles, Melissa A. Michaels
Quantitative Model For The Prediction Of Hydrodynamic Size Of Nonionic Reverse Micelles, Melissa A. Michaels
Theses and Dissertations
The sizes of nonionic reverse micelles were investigated as a function of the molecular structure of the surfactant, the type of oil, the total concentration of surfactant [NP], the ratio of NP4 to total surfactant (r), the water to surfactant molar ratio (ω), temperature, salt concentration, and polar phase. The basis of our investigation was nonylphenol polyethoxylates - NP4 and NP7. Micelle sizes were determined using dynamic light scattering (DLS). A central composite experimental design was used to quantitatively model reverse micelle size as a function of ω, [NP], and r. The model has demonstrated the capability of predicting the …
A Prelude To A Third Dimension Of The Periodic Table: Superatoms Of Aluminum Iodide Clusters, Naiche Owen Jones
A Prelude To A Third Dimension Of The Periodic Table: Superatoms Of Aluminum Iodide Clusters, Naiche Owen Jones
Theses and Dissertations
Calculations have been carried out to investigate the stability and electronic structure of aluminum iodide clusters using first principles gradient-corrected density functional theory. Analysis of A113Ix-, A114Ix-, and A17I- clusters reveals that their stability is governed by the geometrically unperturbed A113-, A1142+, and A17+ units, respectively, that are demonstrated to constitute the compact cores of the clusters upon significant iodine content. The compact, icosahedral A113, icosahedral-like A1 14, and capped square bi-pyramid A17 superatom structures of the stable aluminum cores have an analogous electronic configuration to that of halogen, alkaline-earth, and alkaline atoms, respectively. Novel chemistry is demonstrated in superatoms, …
Enhancing The Third-Order Nonlinear Optical Properties Of Porphyrins And Molecular Wires, Jonathan L. Humphrey
Enhancing The Third-Order Nonlinear Optical Properties Of Porphyrins And Molecular Wires, Jonathan L. Humphrey
Theses and Dissertations
The third-order nonlinear optical (NLO) properties of indium tin oxide (ITO) thin films, Fe3+, Mn3+, Co2+ 5,10,15,20-tetrakis-4hydroxytetraphenyl)porphyrin (TPP) films, and a series of ethynyl-linked azobenzene oligomers were investigated using degenerate four wave mixing (DFWM) with 100 fs laser pulses. To measure the NLO of ITO thin films, A DFWM method for measuring thin films on thick substrates was refined for the characterization of films less than 100 nm thick and applied to ITO films ~25 nm thick. It was found that the third-order nonlinear susceptibility of ITO, χ(3)ITO, is purely electronic at 900 - 1300 nm (11000 - 7700 cm-1) …
Photochemical Applications To The Study Of Complexity Phospholipid Bilayer Environments, Christopher John Wohl Jr.
Photochemical Applications To The Study Of Complexity Phospholipid Bilayer Environments, Christopher John Wohl Jr.
Theses and Dissertations
The physical and biophysical properties of a biological membrane model, phosphatidylcholine bilayers, were investigated using novel spiropyran/merocyanine molecular probes. The femtosecond to second dynamics of this system's photochemistry enabled bilayer viscosity and free volume to be studied over a broad time scale. Spiropyrans/merocyanines with different polarity were synthesized by changing the substitution of the indole moiety enabling determination of the trans-membrane properties of the bilayer. In addition, transient grating spectroscopy was used to study thermal energy transfer in phospholipid bilayers on a picosecond time scale.Femtosecond transient absorption spectroscopy was used to study the photo-induced spiropyran ring-opening and isomerization reactions that …