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  Partner: UNT Libraries
 Degree Discipline: Physics
Oligonucleotide guanosine conjugated to gallium nitride nano-structures for photonics.

Oligonucleotide guanosine conjugated to gallium nitride nano-structures for photonics.

Date: August 2008
Creator: Li, Jianyou
Description: In this work, I studied the hybrid system based on self-assembled guanosine crystal (SAGC) conjugated to wide-bandgap semiconductor gallium nitride (GaN). Guanosine is one of the four bases of DNA and has the lowest oxidation energy, which favors carrier transport. It also has large dipole moment. Guanosine molecules self-assemble to ribbon-like structure in confined space. GaN surface can have positive or negative polarity depending on whether the surface is Ga- or N-terminated. I studied SAGC in confined space between two electrodes. The current-voltage characteristics can be explained very well with the theory of metal-semiconductor-metal (MSM) structure. I-V curves also show strong rectification effect, which can be explained by the intrinsic polarization along the axis of ribbon-like structure of SAGC. GaN substrate property influences the properties of SAGC. So SAGC has semiconductor properties within the confined space up to 458nm. When the gap distance gets up to 484nm, the structure with guanosine shows resistance characteristics. The photocurrent measurements show that the bandgap of SAGC is about 3.3-3.4eV and affected by substrate properties. The MSM structure based on SAGC can be used as photodetector in UV region. Then I show that the periodic structure based on GaN and SAGC can have photonic ...
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Energy Losses of Protons Projected through a Plasma Due to Collisions with Electrons of the Plasma for a Variety of Non-Maxwellian Electron Velocity Distributions

Energy Losses of Protons Projected through a Plasma Due to Collisions with Electrons of the Plasma for a Variety of Non-Maxwellian Electron Velocity Distributions

Date: August 1961
Creator: Kregel, Mark Douglas
Description: The purpose of this thesis is to study energy losses suffered by protons in traversing a plasma through collision with the electrons of the plasma. For these electrons a variety of non-Maxwellian velocity distributions are assumed.
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A Computer Analysis of Complex Gamma-Ray Spectra

A Computer Analysis of Complex Gamma-Ray Spectra

Date: August 1965
Creator: Cunningham, William K.
Description: The purpose of this investigation was to provide a method for determining the relative intensities of all gamma rays in a particular spectrum, and thereby determine the relative transition probabilities.
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Galvanomagnetic Phenomena in Arsenic at Liquid Helium Temperatures

Galvanomagnetic Phenomena in Arsenic at Liquid Helium Temperatures

Date: June 1966
Creator: Yarbrough, Jack Lee
Description: The purpose of this investigation was to study some of the transport effects in a single crystal of arsenic at liquid helium temperatures in a magnetic field up to twenty-four kilogauss. The experimental coefficients determined were the isothermal magnetoresistivity and the isothermal Hall resistivity.
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Thermomagnetic Effects in Antimony at 4.2 [degrees]K

Thermomagnetic Effects in Antimony at 4.2 [degrees]K

Date: August 1965
Creator: Taaffe, Thomas J.
Description: The purpose of this investigation was to study the thermoelectric effects in a single crystal of antimony at liquid-helium temperatures.
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A Calculation of the Kaon-Neutron Scattering Cross Section

A Calculation of the Kaon-Neutron Scattering Cross Section

Date: June 1966
Creator: Hooper, Robert Gibson
Description: The purpose of this investigation was to study the scattering processes of K+ mesons with neutrons. In order to do such a study one must first make certain basic assumptions about the type of interaction involved and then proceed to calculate physically meaningful qualities which describe the processes. Thus, the problem is this: assuming the validity of Feynman's rules for these strongly interacting particles, calculate the differential and total scattering cross sections for the interaction of scalar K+ mesons and neutrons.
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Analyzing Magnet System for the Electrostatic Accelerator

Analyzing Magnet System for the Electrostatic Accelerator

Date: August 1954
Creator: Young, Thomas E.
Description: This thesis describes the design and construction of a linear accelerator, specifically, a positive-ion source, a high voltage supply, an accelerating column, and the necessary associated vacuum system.
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Stochastic Mechanical Systems

Stochastic Mechanical Systems

Date: August 1960
Creator: Bost, Robert Berton
Description: To understand the phenomena associated with such stochastic processes and to predict, at least qualitatively, the behavior of mechanical systems within environments which are completely random in time, new mechanical tools are necessary. Fortunately, the derivation of these tools does not necessitate a complete departure from existing theories. In fact, they may be considered as an extension of the well-defined theory of the integral transform, in particular, the exponential Fourier integral transform.
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Dynamical Friction Coefficients for Plasmas Exhibiting Non-Spherical Electron Velocity Distributions

Dynamical Friction Coefficients for Plasmas Exhibiting Non-Spherical Electron Velocity Distributions

Date: August 1961
Creator: Williams, G. Bruce
Description: This investigation is designed to find the net rate of decrease in the component of velocity parallel to the original direction of motion of a proton moving through an electron gas exhibiting a non-spherical velocity distribution.
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D-D and D-T Neutron Excitation of Energy Levels in Cs133

D-D and D-T Neutron Excitation of Energy Levels in Cs133

Date: January 1961
Creator: Dawson, Horace Ray
Description: The purpose of this experiment was to make positive assignment of the Cs133 energy levels excited by the inelastic scattering of neutrons.
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A Study of Emitter Drift in Transistors

A Study of Emitter Drift in Transistors

Date: August 1961
Creator: Malone, Farris Douglas
Description: The purpose of this investigation was to determine the parameters of emitter drift and to suggest a mechanism for this phenomenon.
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Temperature Dependence of the Magnetic Susceptibility of the Organic Free Radical Galvinoxyl

Temperature Dependence of the Magnetic Susceptibility of the Organic Free Radical Galvinoxyl

Date: August 1965
Creator: Morphew, Sam W.
Description: This thesis examines temperature dependence of magnetic susceptibility of the organic free radical galvinoxyl.
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Design and Testing of a Corona Column and a Closed Gas Distribution System for a Tandem Van de Graaff Voltage Generator

Design and Testing of a Corona Column and a Closed Gas Distribution System for a Tandem Van de Graaff Voltage Generator

Date: June 1962
Creator: Gray, Thomas Jack
Description: The purpose of this study had been to design and test a corona column and an insulating gas distribution system for a small tandem Van de Graaff. The intent of this paper is to describe the gas handling system and to compare experimentally the effects of corona electrode shape on the corona current carried between adjacent sections of the column.
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A Microwave Spectrometer for Narrow-line Electron Spin Resonance Studies

A Microwave Spectrometer for Narrow-line Electron Spin Resonance Studies

Date: January 1966
Creator: Neie, Van ElRoy
Description: This thesis explores the basic theory, design and construction of electron spin resonance spectrometer.
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A Vacuum Tube for an Electrostatic Generator

A Vacuum Tube for an Electrostatic Generator

Date: August 1966
Creator: Pool, John Reginald
Description: The purpose of this study has been to construct two accelerating tubes with small beam apertures for the Van de Graaff, modifying the prototype tube designed and tested by Wiley (20), to design and construct a vacuum system for evacuating the tubes, and to determine the characteristics of the tube under operating conditions while installed in the generator.
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The Diurnal Variation of Cosmic Radiation

The Diurnal Variation of Cosmic Radiation

Date: August 1965
Creator: Fowler, Brooks C.
Description: The primary purpose of this investigation was to study the diurnal variation of cosmic-ray intensity.
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Nuclear Magnetic Resonance in a Crystalline Stable Free Radical--Wurster's Blue Perchlorate

Nuclear Magnetic Resonance in a Crystalline Stable Free Radical--Wurster's Blue Perchlorate

Date: August 1965
Creator: McCann, Thomas E.
Description: This thesis investigates the nuclear magnetic resonance in a crystalline stable free radical.
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Design and Testing of a Positive Ion Accelerator and Necessary Vacuum System

Design and Testing of a Positive Ion Accelerator and Necessary Vacuum System

Date: August 1953
Creator: McKay, Vern A.
Description: This thesis is a study of the design and testing of a positive ion accelerator and necessary vacuum system.
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Antiferromagnetic Ordering in Picryl-Amino-Carbazyl

Antiferromagnetic Ordering in Picryl-Amino-Carbazyl

Date: August 1964
Creator: Porter, Wilbur A.
Description: The purpose of the experiment was to investigate other paramagnetic salts to determine whether the W. B. perchlorate type peak was more common than previously suspected. An organic salt, picryl-n-amino-carbazyl, was chosen.
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The Optimum Design of a Broad-band Helix for Use in Electron Spin Resonance

The Optimum Design of a Broad-band Helix for Use in Electron Spin Resonance

Date: June 1967
Creator: Garlow, John R.
Description: This thesis examines optimum designs for broad-band helix to be used in electron spin resonance.
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Electrical Conductivity in Thin Films

Electrical Conductivity in Thin Films

Date: May 1973
Creator: Meyer, Frederick Otto
Description: This thesis deals with electrical conductivity in thin films. Classical and quantum size effects in conductivity are discussed including some experimental evidence of quantum size effects. The component conductivity along the applied electric field of a thin film in a transverse magnetic field is developed in a density matrix method.
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Effect of Sample Geometry on Magnetomorphic Oscillations in the Hall Effect in Cadium at Liquid-Helium Temperatures

Effect of Sample Geometry on Magnetomorphic Oscillations in the Hall Effect in Cadium at Liquid-Helium Temperatures

Date: June 1967
Creator: Fielder, James Thomas
Description: This thesis presents observations on size-effect oscillations in the Hall effect in an oriented single crystal of highly pure cadmium at liquid-helium temperatures. All measurements were made in transverse magnetic field.
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The Effects of Cesium Deposition and Gas Exposure on the Field Emission Properties of Single Wall and Multiwall Carbon Nanotubes

The Effects of Cesium Deposition and Gas Exposure on the Field Emission Properties of Single Wall and Multiwall Carbon Nanotubes

Date: May 2002
Creator: Wadhawan, Atul
Description: The effects of Cs deposition on the field emission (FE) properties of single-walled carbon nanotube (SWNT) bundles were studied. In addition, a comparative study was made on the effects of O2, Ar and H2 gases on the field emission properties of SWNT bundles and multiwall carbon nanotubes (MWNTs). We observed that Cs deposition decreases the turn-on field for FE by a factor of 2.1 - 2.9 and increases the FE current by 6 orders of magnitude. After Cs deposition, the FE current versus voltage (I-V) curves showed non-Fowler-Nordheim behavior at large currents consistent with tunneling from adsorbate states. At lower currents, the ratio of the slope of the FE I-V curves before and after Cs deposition was approximately 2.1. Exposure to N2 does not decrease the FE current, while exposure to O2 decreases the FE current. Our results show that cesiated SWNT bundles have great potential as economical and reliable vacuum electron sources. We find that H2 and Ar gases do not significantly affect the FE properties of SWNTs or MWNTs. O2 temporarily reduces the FE current and increases the turn-on voltage of SWNTs. Full recovery of these properties occurred after operation in UHV. The higher operating voltages in an ...
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The Effect of Average Grain Size on Polycrystalline Diamond Films

The Effect of Average Grain Size on Polycrystalline Diamond Films

Date: May 2002
Creator: Abbott, Patrick Roland
Description: The work function of hydrogen-terminated, polycrystalline diamond was studied using ultraviolet photoelectron spectroscopy. Polycrystalline diamond films were deposited onto molybdenum substrates by electrophoresis for grain sizes ranging from 0.3 to 108 microns. The work function and electron affinity were measured using 21.2 eV photons from a helium plasma source. The films were characterized by x-ray photoelectron spectroscopy to determine elemental composition and the sp2/sp3 carbon fraction. The percentage of (111) diamond was determined by x-ray diffraction, and scanning electron microscopy was performed to determine average grain size. The measured work function has a maximum of 5.1 eV at 0.3 microns, and decreases to 3.2 eV at approximately 4 microns. Then the work function increases with increasing grain size to 4.0 eV at 15 microns and then asymptotically approaches the 4.8 eV work function of single crystal diamond at 108 microns. These results are consistent with a 3-component model in which the work function is controlled by single-crystal (111) diamond at larger grain sizes, graphitic carbon at smaller grain sizes, and by the electron affinity for the intervening grain sizes.
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