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Two-photon Photoemission of Organic Semiconductor Molecules on Ag(111)

Description: Angle- and time-resolved two-photon photoemission (2PPE) was used to study systems of organic semiconductors on Ag(111). The 2PPE studies focused on electronic behavior specific to interfaces and ultrathin films. Electron time dynamics and band dispersions were characterized for ultrathin films of a prototypical n-type planar aromatic hydrocarbon, PTCDA, and representatives from a family of p-type oligothiophenes.In PTCDA, electronic behavior was correlated with film morphology and growth modes… more
Date: May 15, 2008
Creator: Yang, Aram & Yang, Aram
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries Government Documents Department
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Temperature dependence of the interface moments in Co2MnSi thin films

Description: X-ray magnetic circular dichroism (XMCD) is utilized to explore the temperature dependence of the interface moments in Co{sub 2}MnSi (CMS) thin films capped with aluminium. By increasing the thickness of the capping layer we demonstrate enhanced interface sensitivity of the measurements and the existence of a thin Mn oxide layer at the CMS/Al interface even when a thick capping layer is used. We show that for well ordered L2{sub 1} CMS films there is no significant variation in either the Co or… more
Date: March 15, 2008
Creator: Arenholz, Elke; Telling, N.; Keatley, P.; Shelford, L.; Arenholz, E.; van der Laan, G. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Examination of the platinum effect on the oxidation behavior ofnickel-aluminide coatings

Description: Oxidation resistant nickel-aluminide coatings are designed to develop a protective alumina scale during high temperature exposure. It is well established that platinum additions, typically about 6-8 at%, provide substantial improvements in oxidation resistance of such coatings, yet the nature of the platinum effect is still not fully understood. In this work, the oxidation behavior of two commercial NiAl and NiPtAl coatings deposited on the same Ni-base single crystal alloy CMSX-4 was analyzed.… more
Date: May 15, 2007
Creator: Hou, Peggy Y. & Tolpygo, V. K.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Built-in and Induced Polarization Across LaAlO3/SrTiO3 Heterojunctions

Description: Ionic crystals terminated at oppositely charged polar surfaces are inherently unstable and expected to undergo surface reconstructions to maintain electrostatic stability. Essentially, an electric field that arises between oppositely charged atomic planes gives rise to a built-in potential that diverges with thickness. Here we present evidence of such a built-in potential across polar LaAlO{sub 3} thin films grown on SrTiO{sub 3} substrates, a system well known for the electron gas that forms a… more
Date: August 15, 2011
Creator: Guneeta, Singh-Bhalla
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Dislocation dynamics simulations of plasticity at small scales

Description: As metallic structures and devices are being created on a dimension comparable to the length scales of the underlying dislocation microstructures, the mechanical properties of them change drastically. Since such small structures are increasingly common in modern technologies, there is an emergent need to understand the critical roles of elasticity, plasticity, and fracture in small structures. Dislocation dynamics (DD) simulations, in which the dislocations are the simulated entities, offer a w… more
Date: December 15, 2010
Creator: Zhou, Caizhi
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries Government Documents Department
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Ultrafast Photovoltaic Response in Ferroelectric Nanolayers

Description: We show that light drives large-amplitude structural changes in thin films of the prototypical ferroelectric PbTiO3 via direct coupling to its intrinsic photovoltaic response. Using time-resolved x-ray scattering to visualize atomic displacements on femtosecond timescales, photoinduced changes in the unit-cell tetragonality are observed. These are driven by the motion of photogenerated free charges within the ferroelectric and can be simply explained by a model including both shift and screenin… more
Date: February 15, 2012
Creator: Daranciang, Dan
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Metal thin film growth on multimetallic surfaces: From quaternary metallic glass to binary crystal

Description: The work presented in this thesis mainly focuses on the nucleation and growth of metal thin films on multimetallic surfaces. First, we have investigated the Ag film growth on a bulk metallic glass surface. Next, we have examined the coarsening and decay of bilayer Ag islands on NiAl(110) surface. Third, we have investigated the Ag film growth on NiAl(110) surface using low-energy electron diffraction (LEED). At last, we have reported our investigation on the epitaxial growth of Ni on NiAl(110) … more
Date: December 15, 2010
Creator: Jing, Dapeng
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries Government Documents Department
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Reactivity of Au nanoparticles supported over SiO2 and TiO2 studiedby ambient pressure photoelectron spectroscopy

Description: The influence of the metal cluster size and the identity of the support on the reactivity of gold based catalysts have been studied in the CO oxidation reaction. To overcome the structural complexity of the supported catalysts, gold nanoparticles synthesized from colloidal chemistry with precisely controlled size have been used. Those particles were supported over SiO{sub 2} and TiO{sub 2} and their catalytic activity was measured in a flow reactor. The reaction rate was dependent on the partic… more
Date: April 15, 2009
Creator: Herranz, Tirma; Deng, Xingyi; Cabot, Andreu; Alivisatos, Paul; Liu, Zhi; Soler-Illia, Galo et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Novel Membranes and Processes for Oxygen Enrichment

Description: The overall goal of this project is to develop a membrane process that produces air containing 25-35% oxygen, at a cost of $25-40/ton of equivalent pure oxygen (EPO2). Oxygen-enriched air at such a low cost will allow existing air-fueled furnaces to be converted economically to oxygen-enriched furnaces, which in turn will improve the economic and energy efficiency of combustion processes significantly, and reduce the cost of CO{sub 2} capture and sequestration from flue gases throughout the U.S… more
Date: November 15, 2011
Creator: Lin, Haiqing
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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A Novel Low Thermal Budget Thin-Film Polysilicon Fabrication Process for Large-Area, High-Throughput Solar Cell Production

Description: A novel thin-film poly-Si fabrication process has been demonstrated. This low thermal budget process transforms the single- and multi-layer amorphous silicon thin films into a poly-Si structure in one simple step over a pulsed rapid thermal annealing process with the enhancement of an ultrathin Ni layer. The complete poly-Si solar cell was fabricated in a short period of time without deteriorating the underneath glass substrate. The unique vertical crystallization process including the mechanis… more
Date: August 15, 2010
Creator: Kuo, Yue
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Strain engineering to control the magnetic and magnetotransport properties of La0.67Sr0.33MnO3 thin films

Description: This work studies the control of the magnetic and magnetotransport properties of La{sub 0.67}Sr{sub 0.33}MnO{sub 3} thin films through strain engineering. The strain state is characterized by the tetragonal distortion (c/a ratio), which can be varied continuously between a compressive strain of 1.005 to a tensile strain of 0.952 by changing the type of substrate, the growth rate, and the presence of an underlying La{sub 0.67}Sr{sub 0.33}FeO{sub 3} buffer layer. Increasing tensile tetragonal dis… more
Date: June 15, 2010
Creator: Yang, F.; Kemik, N.; Biegalski, M.D.; Christen, H.M.; Arenholz, E. & Takamura, Y.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Nitrogen doped zinc oxide thin film

Description: To summarize, polycrystalline ZnO thin films were grown by reactive sputtering. Nitrogen was introduced into the films by reactive sputtering in an NO{sub 2} plasma or by N{sup +} implantation. All ZnO films grown show n-type conductivity. In unintentionally doped ZnO films, the n-type conductivities are attributed to Zn{sub i}, a native shallow donor. In NO{sub 2}-grown ZnO films, the n-type conductivity is attributed to (N{sub 2}){sub O}, a shallow double donor. In NO{sub 2}-grown ZnO films, … more
Date: December 15, 2003
Creator: Li, Sonny X.
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries Government Documents Department
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Specimen charging on thin films with one conducting layer:Discussion of physical principles

Description: While the most familiar consequences of specimen charging in transmission electron microscopy can be eliminated by evaporating a thin conducting film (such as a carbon film) onto an insulating specimen, or by preparing samples directly on such a conducting film to begin with, a more subtle charging effect still remains. We argue here that specimen charging is in this case likely to produce a dipole sheet rather than a layer of positive charge at the surface of the specimen. A simple model of th… more
Date: April 15, 2003
Creator: Glaeser, Robert M. & Downing, Kenneth H.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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A nonstoichiometric structural model to characterize changes in the nickel hydroxide electrode during cycling

Description: Experimental capacities and mass changes are recorded using an electrochemical quartz crystal microbalance during the first 9 charge and discharge cycles of nickel hydroxide thin films cycled in 3.0 weight percent (wt%) potassium hydroxide electrolyte. For the first time, the film capacities have been corrected for the oxygen evolution side reaction, and the data used as input into the point defect-containing structural model to track the changes that occur during short-term cycling. Variations… more
Date: September 15, 2003
Creator: Srinivasan, Venkat; Bahne, C. Cornilsen & Weidner, John W.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Plasma Deposited Diamond-Like Carbon Films for Large Neutralarrays

Description: To understand how large systems of neurons communicate, we need to develop methods for growing patterned networks of large numbers of neurons. We have found that diamond-like carbon thin films formed by energetic deposition from a filtered vacuum arc carbon plasma can serve as ''neuron friendly'' substrates for the growth of large neural arrays. Lithographic masks can be used to form patterns of diamond-like carbon, and regions of selective neuronal attachment can form patterned neural arrays. … more
Date: July 15, 2004
Creator: Brown, I. G.; Blakely, E. A.; Bjornstad, K. A.; Galvin, J. E.; Monteiro, O. R. & Sangyuenyongpipat, S.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Comments on 'Pore-Scale Visulization of Colloid Transport andRetention in Partly Saturated Porous Media'

Description: The recent study by Crist et al. (2004) attempted to provide pore scale insights into mechanisms responsible for controlling colloid transport in unsaturated porous media. However, because they relied on images obtained along surfaces that were open to the atmosphere, artificial evaporation resulted in 2 more critical artifacts; formation of air-water-solid (AWS) contact lines, and advection/deposition of colloids to AWS contact lines. These evaporation-related artifacts need to be addressed be… more
Date: February 15, 2005
Creator: Wan, Jiamin & Tokunaga, Tetsu K.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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3D highly oriented nanoparticulate and microparticulate array ofmetal oxide materials

Description: Advanced nano and micro particulate thin films of 3d transition and post-transition metal oxides consisting of nanorods and microrods with parallel and perpendicular orientation with respect to the substrate normal, have been successfully grown onto various substrates by heteronucleation, without template and/or surfactant, from the aqueous condensation of solution of metal salts or metal complexes (aqueous chemical growth). Three-dimensional arrays of iron oxide nanorods and zinc oxide nanorod… more
Date: September 15, 2006
Creator: Vayssieres, Lionel; Guo, Jinghua & Nordgren, Joseph
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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High rate PLD of diamond-like-carbon utilizing high repetition rate visible lasers

Description: Pulsed Laser Deposition (PLD) has been shown to be an effective method for producing a wide variety of thin films of high-value-added materials. The high average powers and high pulse repetition frequencies of lasers under development at LLNL make it possible to scale-up PLD processes that have been demonstrated in small systems in a number of university, government, and private laboratories to industrially meaningful, economically feasible technologies. A copper vapor laser system at LLNL has … more
Date: September 15, 1994
Creator: McLean, William, II; Fehring, Edward J.; Dragon, Ernest P. & Warner, Bruce E.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Preliminary Results of Testing of Flow Effects on Evaporator Scaling

Description: This investigation has focused on the effects of fluid flow on solids deposition from solutions that simulate the feed to the 2H evaporator at the Savannah River Site. Literature studies indicate that the fluid flow (or shear) affects particle-particle and particle-surface interactions and thus the phenomena of particle aggregation in solution and particle deposition (i.e., scale formation) onto solid surfaces. Experimental tests were conducted with two configurations: (1) using a rheometer to … more
Date: February 15, 2002
Creator: Hu, M.Z.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Integrated Mirco-Machined Hydrogen Gas Sensors

Description: The widespread use of hydrogen as both an industrial process gas and an energy storage medium requires fast, selective detection of hydrogen gas. This report discusses the development of a new type of solid-state hydrogen gas sensor that couples novel metal hydride thin films with a MEMS (Micro-Electro-Mechanical System) structure known as a micro-hotplate. In this project, Micro-hotplate structures were overcoated with engineered multilayers that serve as the active hydrogen-sensing layer. The… more
Date: December 15, 2005
Creator: DiMeo, Frank, Jr.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Borocarbide thin films and tunneling measurements.

Description: The results obtained by their group in thin film fabrication and STM tunneling on superconducting borocarbides YNi{sub 2}B{sub 2}C have been be briefly reviewed. Results concerning the microwave surface impedance and the S/N planar junctions on LuNi{sub 2}B{sub 2}C thin films have been also presented and analyzed. These new data unambiguously confirm the full BCS nature of the superconducting gap in borocarbides and the absence of significant pair-breaking effects in LuNi{sub 2}B{sub 2}C.
Date: June 15, 2000
Creator: Iavarone, M.; Andreone, A.; Cassinese, A.; Dicapual, R.; Giannil, L.; Vagliol, R. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Preferred orientation in polycrystalline Cu(In,Ga)Se{sub 2} and its effect on absorber thin-films and devices

Description: The purpose of this work is to investigate physical properties of Cu(In,Ga)Se{sub 2} polycrystalline thin-films exhibiting a high degree of preferred orientation. Specifically, by using Na-free Cu(In,Ga)Se{sub 2} thin-films, it is intended to experimentally determine differences (if any) between films with a (110/102)-preferred orientation and films with a (112)-preferred orientation. The approach to the problem is a systematic comparative analysis of film and device properties in which the mos… more
Date: May 15, 2000
Creator: Contreras, M. A.; Jones, K. M.; Gedvilas, L. & Matson, R.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Electrochromism in copper oxide thin films

Description: Transparent thin films of copper(I) oxide prepared on conductive SnO2:F glass substrates by anodic oxidation of sputtered copper films or by direct electrodeposition of Cu2O transformed reversibly to opaque metallic copper films when reduced in alkaline electrolyte. In addition, the same Cu2O films transform reversibly to black copper(II) oxide when cycled at more anodic potentials. Copper oxide-to-copper switching covered a large dynamic range, from 85% and 10% photopic transmittance, with a c… more
Date: August 15, 2000
Creator: Richardson, T. J.; Slack, J. L. & Rubin, M. D.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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