| Discrete Optimization of Electronic Hyperpolarizabilities in a Chemical Subspace |
04-Nov-2009 |
10 pages |
| Authors:
Jan Andzelm; Adam Rawlett; Weitao Yang; B C Rinderspacher; Joseph Dougherty; David N Beratan; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
|
 | We introduce a general optimization algorithm based on an interpolation of property values on a hypercube. Each vertex of the hypercube represents a molecule, while the interior of the interpolation represents a virtual superposition (alchemical mutation) of molecules. The resultant algorithm is similar to branch-and-bound/tree-search methods. We apply the algorithm to the optimization of the first electronic hyperpolarizability for several tolane libraries. The search includes structural and conformational information. Geometries ... |
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| Next Generation Highly Conducting Organic Films Using Novel Donor-Acceptor Molecules for Opto-Electronic Applications |
Jun-2009 |
16 pages |
| Authors:
Eric Forsythe; Jianmin Shi; David Morton; ARMY RESEARCH LAB ADELPHI MD SENSORS AND ELECTRON DEVICES DIRECTORATE
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| This two-year DRI is intended to address the Army's need for two-dimensional, conformal, large-area electronics by developing techniques that will lead to the printing of conducting organic materials as a primary build-block that will enable such low-cost, large area applications. In the first year, we worked on developing novel organic based molecules using the donor-acceptor design concepts and developing a more fundamental understanding of donor acceptor molecule stacking in order ... |
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| Investigation of Electrical and Optical Properties of Bulk III-V Ternary Semiconductors |
Mar-2009 |
66 pages |
| Authors:
Travis C Gomez; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING AND MANAGEMENT/DEPT OF ENGINEERING PHYSICS
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| Bulk grown III-V ternary semiconductors of In0.08Ga0.92Sb and In0.15Ga0.85As were investigated through Hall-effect and photoluminescence measurements to determine carrier concentration, mobility, sheet resistivity, and luminescence spectrum. In the past, epitaxial layers of ternary compounds have been grown on binary compound substrates, and thus very limited lattice matched ternary alloys were available. Recently, bulk grown ternary substrates have been developed, and it has presented a renewed interest in using these substrates ... |
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| Plastic Optoelectronics: Injection Lasers Fabricated from Soluble Semiconducting Polymers and Bulk Heterojunction Solar Cells Fabricated from Soluble Semiconducting Polymers |
17 APR 2008 |
15 pages |
| Authors:
Alan J. Heeger; Guillermo Bazan; CALIFORNIA UNIV REGENTS SANTA BARBARA
|
| We summarize progress on bulk heterojunction (BHJ) "plastic" solar cells: BHJ solar cells are based on phase-separated blends of polymer semiconductors and fullerene derivatives. Because of self-assembly on the nanometer length scale, excitons formed after absorption of solar irradiation diffuse to a heterojunction prior to recombination and are dissociated at the polymer/fullerene interface. Ultrafast charge transfer from semicondueting polymers to fullerenes guarantees that the quantum efficiency for charge transfer (CT) ... |
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| Platinum Acetylide Two-Photon Chromophores (Preprint) |
APR 2007 |
62 pages |
| Authors:
Aaron R. Burke; Thomas M. Cooper; Joy E. Rogers; Jonathan E. Slagle; Douglas M. Krein; Benjamin C. Hall; Albert Fratini; Daniel G. McLean; UNIVERSAL ENERGY SYSTEMS INC DAYTON OH HUMAN FACTORS DIV
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| To explore the photophysics of platinum acetylide chromopores having strong two photon cross section, we have investigated the synthesis and spectroscopic characterization of a series of platinum acetylide complexes that feature highly π-conjugated ligands substituted with π-donor or ?acceptor moieties. The molecules (numbered 1-4) considered in the present work are NLO-functionalized analogs of bis(phenylethynyl)bis(bributylphosphine)platinum(II) complexes. Molecule 1 carries two benzothiazolylfluorene and molecule 2 carries two diphenylaminofluorene substituents bound to the ... |
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| Microbial Reduction of Chromium from the Hexavalent to Divalent State |
2007 |
11 pages |
| Authors:
Tyrone L. Daulton; Brenda J. Little; Joanne Jones-Meehan; Douglas A. Blom; Lawrence F. Allard; NAVAL RESEARCH LAB STENNIS SPACE CENTER MS OCEANOGRAPHY DIV
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| We demonstrate that Shewanella oneidensis, a metal-reducing bacteria species with cytoplasmic-membrane-bound reductases and remarkably diverse respiratory capabilities, reduced Cr(VI) to Cr(II) in anaerobic cultures where chromate was the sole terminal electron acceptor. Individual cell microanalysis by transmission electron microscopy (TEM) using electron energy-loss spectroscopy (EELS) and energy dispersive X-ray spectroscopy (EDXS) demonstrates Cr(II) concentrated near the cytoplasmic membrane, suggesting the terminal reduction pathway is intracellularly localized. Further, estimated cellular Cr(II) ... |
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| Effects of Solvation on One- and Two-Photon Spectra of Coumarin Derivatives: A Time-Dependent Density Functional Theory Study (Postprint) |
2007 |
13 pages |
| Authors:
Ruth Pachter; Kiet A. Nguyen; Paul N. Day; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH MATERIALS AND MANUFACTURING DIRECTORATE
|
| We report one- and two-photon absorption excitation energies and cross sections for a series of 7-aminocoumarins using time-dependent density functional theory with various basis sets and functionals, including exchange-correlation functionals using the Coulomb-attenuating method, to evaluate their performance in the gas phase and in solvents. Except for the results of one functional, the computed one-photon excitation energies and transition dipole moments are in good agreement with experiment. The range of ... |
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| Platinum Acetylide Two-Photon Chromophores (Postprint) |
2007 |
16 pages |
| Authors:
Paul A. Fleitz; Thomas M. Cooper; Joy E. Rogers; Jonathan E. Slagle; Aaron R. Burke; Douglas M. Krein; Benjamin C. Hall; Albert Fratini; Daniel G. McLean; UES INC DAYTON OH
|
| To explore the photophysics of platinum acetylide chromopores having strong two-photon absorption cross-sections, we have investigated the synthesis and spectroscopic characterization of a series of platinum acetylide complexes that feature highly π-conjugated ligands substituted with π-donor or ?acceptor moieties. The molecules (numbered 1-4) considered in the present work are NLO-functionalized analogs of bis(phenylethynyl)bis(bributylphosphine)platinum(II) complexes. Molecule 1 carries two benzothiazolylfluorene and molecule 2 carries two diphenylaminofluorene substituents bound to the central ... |
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| A Review of Green Strategies to Prevent or Mitigate Microbiologically Influenced Corrosion |
2007 |
12 pages |
| Authors:
Brenda Little; Jason Lee; Richard Ray; NAVAL RESEARCH LAB STENNIS SPACE CENTER MS OCEANOGRAPHY DIV
|
| Two approaches to control microbiologically influenced corrosion (MIC) have ben developed that do not require the use of biocides. These strategies include the following: i) use of biofilms to inhibit or prevent corrosion, and ii)manipulation (removal or addition) of an electron acceptor. (e.g. oxygen, sulphate or nitrate) to influence the microbial population. In both approaches the composition of the microbial community is affected by small perturbations in the environment (e.g. ... |
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| Effects of Solvation On One- and Two-Photon Spectra of Coumarin Derivatives: A TDDFT Study (Preprint) |
OCT 2006 |
36 pages |
| Authors:
Kiet A. Nguyen; Paul N. Day; Ruth Pachter; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH SURVIVABILITY AND SENSOR MATERIALS DIV/HARDENED MATERIALS
|
| We report one- (OPA) and two-photon absorption (TPA) excitation energies and cross sections for a series of 7-aminocoumarins using time-dependent density functional theory with various basis sets and functionals, including exchange-correlation functionals using the Coulomb-attenuating method (CAMB3LYP and mCAMB3LYP), to evaluate their performance in gas-phase and in solvents. Except for the CAMB3LYP results , the computed OPA excitation energies and transition dipole moments are in good agreement with experiment. The ... |
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| Nanoscale Polymeric Photocells by Advanced Electrospinning |
20 JUL 2006 |
51 pages |
| Authors:
Anvar Zakhidov; John Ferraris; Kenneth Balkus; TEXAS UNIV AT DALLAS RICHARDSON
|
| We presented detailed study of postproduction neat treatment of organic solar cells based on RR-P3HT:PCBM composite in a wide temperature range. The efficiency of such device was significantly Improved by postproduction heat treatment. Optimized parameters yielded >3% efficiency for devices on glass substrates and of |
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| Effects of Conjugation in Length and Dimension on Spectroscopic Properties of Fluorene-Based Chromophores from Experiment and Theory (Preprint) |
JUL 2006 |
38 pages |
| Authors:
Loon-Seng Tao; Paul A. Fleitz; Ruth Pachter; Kiet A. Nguyen; Joy E. Rogers; Jonathan E. Slagle; Paul N. Day; Ramamurthi Kannan; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH SURVIVABILITY AND SENSOR MATERIALS DIV/HARDENED MATERIALS
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| A series of one-photon (OPA) absorption spectra for fluorine-based donor pi acceptor molecules is presented and spectroscopically assigned, based upon the results obtained from time-dependent density functional theory (TDDFT). The computed excitation energies were generally shown to be in good agreement with experiment, particularly when compared to results from measurements carried out in a nonpolar solvent, which were available for some molecules. The computed oscillator strengths may resolve discordant experimental ... |
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| Towards Resonant-State THz Laser Based on Strained p-Ge and SiGe QW Structures |
JUL 2006 |
57 pages |
| Authors:
Kagan M. Solomonovich; EUROPEAN OFFICE OF AEROSPACE RESEARCH AND DEVELOPMENT FPO NEW YORK 09421
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| The main focus of the project is to investigate the possibilities for population inversion between two-dimensional (2D) acceptor states and THz lasing in strained selectively doped SiGe quantum well (QW) structures, as well as the microscopic mechanism of a population inversion in resonant-state p-Ge laser (RSL) and conditions for continuous-wave (cw) operation of RSL and its parameters (the radiation spectrum, the range of frequency tuning, the output power, and the ... |
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| Biological Fuel Cell Functional as an Active or Reserve Power Source |
JUN 2006 |
26 pages |
| Authors:
Jr Walker Charles W.; Alyssa L. Walker; ARMY RESEARCH LAB ADELPHI MD
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| A biological fuel cell was constructed in which the metabolism of glucose by yeast provides the electrons. A two-compartment plexiglas fuel cell was constructed with platinum electrodes separated by a proton-conducting membrane. One half of the cell contained yeast, Saccharomyces cerevisiae, glucose, and an electron mediator, methylene blue. The other half contained an electron acceptor, potassium ferricyanide. Electrons produced during the metabolism of glucose by the yeast were captured by ... |
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| Dissolved Hydrogen Analyzer |
MAY 2006 |
40 pages |
| Authors:
Lebron Carmen; NAVAL FACILITIES ENGINEERING SERVICE CENTER PORT HUENEME CA
|
| Monitored natural attenuation (MNA) is a cost-effective remediation approach that is applicable to many sites and embraced by the U.S. Department of Defense (DoD). MNA can be used to mitigate petroleum hydrocarbon, chlorinated hydrocarbon, and metal-contaminated sites as an alternative to groundwater pump-and-treat methods. Determining MNA's technical applicability for a given site is based on sampling and analysis, data evaluation and modeling, and long-term monitoring. Parameters that are evaluated include ... |
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| Nonlinear Optical Properties of Nanostructured Supramolecular Organic Semiconductor |
2006 |
5 pages |
| Authors:
JaeTae Seo; Qiguang Yang; SeongMin Ma; Liawood Creekmore; Russell Battle; Ashley Jackson; Tifney Skyles; Herbert Brown; Bagher Tabibi; Sam-Shajing Sun; Chen Zhang; HAMPTON UNIV VA DEPT OF PHYSICS
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| Resonant third-order optical susceptibility and hyperpolarizability of donor polymer in chloroform were revealed to be ~2.5 - 9.1x10(exp -20) sq m/V2 and ~8.6 10(exp -42) m5/V2 by degenerate four-wave mixing in nanosecond scale at 532 nm, which was attributed to the resonant enhancement. |
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| Variable Gap Conjugated Polymers |
DEC 2005 |
15 pages |
| Authors:
John R. Reynolds; FLORIDA UNIV GAINESVILLE CENTER FOR MACROMOLECULAR SCIENCE AND ENGINEERING
|
| Conjugated polymers having structurally controlled valence (HOMO) and conduction (LUMO) states, along with systems having specific electron donor and acceptor capabilities, Have been developed as optoelectronic materials for photovoltaic, electrochromic, and charge carrier transport properties. Prototype photovoltaic and electrochromic device platforms have been developed and utilized to test and optimize these polymer properties. |
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| Novel Nano-Phase Ordered Polymer Systems for Efficient Photovoltaic Applications |
07 MAR 2005 |
24 pages |
| Authors:
Sam Sun; NORFOLK STATE UNIV VA
|
| A novel polythiophene -DBAB- type block copolymer system has been developed, where D is a new sulfide derivatized polythiophene donor block, A is a fluorine derivatized polythiophene acceptor block, and B is a non conjugated and flexible bridge chain. In donor block, a dithiathiophene ring derivatized polythiophene was used due to it is chemically more stable than the no-ring analogs. This structure also drastically limits the large steric hindrance in ... |
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| Real Time Monitoring of Signaling Pathways in Biological Cells |
14 FEB 2005 |
13 pages |
| Authors:
Louise J. Brogan; Brian D. Cohen; EVIDENT TECHNOLOGIES TROY NY
|
| The goal of this research project was to determine the efficacy of EviTags as in situ nanoprobes. The experimental design used a fluorescence resonance energy transfer (FRET)-based approach to show how EviTags can monitor real-time cellular events, in particular, cell surface receptor trafficking and mRNA stability. EviTags were hypothesized to be excellent FRET donors when paired with organic dyes as acceptors because of their unique optical properties. The broad absorption ... |
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| Cost and Performance Report of Dissolved Hydrogen Analyzer |
JAN 2005 |
33 pages |
| Authors:
Carmen A. Lebron; Barbara Sugiyama; Patrick J. Evans; Mary Trute; Roger Olsen; NAVAL FACILITIES ENGINEERING SERVICE CENTER PORT HUENEME CA
|
| Monitored natural attenuation (MNA) is a cost-effective remediation approach that is applicable to many sites and has been embraced by the U.S. Department of Defense (DOD). Monitored natural attenuation can be used to mitigate petroleum hydrocarbon, chlorinated hydrocarbon, and metal-contaminated sites as an alternative to groundwater pump and treat methods. Determination of MNA's technical applicability for a given site is based on sampling and analysis, data evaluation and modeling, and ... |
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| The Effect of Microbial FE(III) Reduction on Smectite Flocculation |
2005 |
9 pages |
| Authors:
Jin-Wook Kim; Yoko Furukawa; Hailiang Dong; Steve W. Newell; NAVAL RESEARCH LAB WASHINGTON DC
|
| This study was undertaken to investigate the changes in flocculation properties of Fe-rich smectite (nontronite, NAu-1) suspensions, including settling velocity, aggregate size and floc architecture associated with microbial Fe(III)-reduction in the smectite structure. The dissimilatory Fe-reducing bacterium Shewanella oneidensis MR-1 was incubated with lactate as the electron donor and structural Fe(III) as the sole electron acceptor for 3, 12, 24 and 48 h in an aerobic chamber. Two controls were ... |
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| A Center for Organic Photonic Materials Research |
31 OCT 2004 |
68 pages |
| Authors:
Sam Sun; NORFOLK STATE UNIV VA
|
| A Center for Organic Photonic Materials Research (COPMR) was established at Norfolk State University (NSU). Novel and high efficiency optoelectronic and nano structured polymeric materials are the main research focus. Specifically, during the performance period, a series of -DBAB- type of block copolymers, where D is a conjugated electron donating block, A is a conjugated electron withdrawing acceptor block, and B is a non conjugated and flexible bridge unit, have ... |
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| Supercritical Carbon Dioxide Interaction with Polymeric Materials: Desorption Diffusion Coefficient Measurements |
JUL 2004 |
247 pages |
| Authors:
Wendel J. Shuely; Brian S. Ince; EDGEWOOD CHEMICAL BIOLOGICAL CENTER ABERDEEN PROVING GROUND MD RESEARCH AND TECHNOLOGY DIR
|
| Chemical-polymer compatibility is an important criterion in the development of solvent-based extraction and cleaning systems for removal of toxic contaminants from polymeric surfaces. The potential degradation of polymer properties and performance is especially critical for sensitive equipment cleaning, decontamination, and extraction. The candidate cleaning fluids for sensitive equipment include fluorinations and supercritical fluids. An overall material evaluation strategy has been developed for evaluating the degradation of polymer properties by exposure ... |
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| Preparation and Characterization of the First Binary Titanium Azides, Ti(N3)4, P(C6H5)4Ti(N3)5 and P(C6H5)42Ti(N3)6 and on Linear Ti-N-NN Coordination |
12 MAR 2004 |
21 pages |
| Authors:
Karl O. Christe; Ralf Haiges; Stefan Schneider; Thorsten Schroer; Jerry A. Boatz; ENGINEERING RESEARCH AND CONSULTING INCHUNTSVILLE AL
|
| Where as numerous partially azide-substituted titanium compounds had previously been reported, 1-7 no binary titanium azides were known. In a recent theoretical study the group 4 metal tetrazides M(N3)4 (M = Ti, Zr, Hf, Th) were predicted 8 to be vibrationally stable exhibiting tetrahedral structures with unique linear M-N-NN bond angles (see Figure 1). All previously characterized covalent binary azide species possess bent M-N-NN angles. In this paper we wish ... |
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| Low Temperature Hall Measurements of Neutron Irradiated Silicon Carbide |
MAR 2004 |
82 pages |
| Authors:
Ange1o M. Bonavita; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING AND MANAGEMENT
|
| The purpose of this research was to search for evidence of low temperature annealing from neutron irradiated 4H-silicon carbide. No features suggesting annealing were found below a temperature of 340K. Temperature dependant Hall effect measurements were taken over a range of 100K to 340K recording resistivity, carrier densities, and mobility. Resistivity was noted to increase with irradiations, and carrier densities appeared to decrease, while mobility appeared minimally affected by neutron ... |
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| Carrier Trapping and Current Collapse Mechanism in GaN Metal- Semiconductor Field-Effect Transistors |
21 JAN 2004 |
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| Authors:
A. F. Anwar; Syed S. Islam; Richard T. Webster; AIR FORCE RESEARCH LAB HANSCOM AFB MA SENSORS DIRECTORATE
|
 | A mechanism for current collapse in GaN metal-semiconductor field- effect transistors is proposed, which assumes the existence of acceptor traps with multiple states in the band gap. Current collapse has been experimentally observed in the current-voltage characteristic after the drain voltage sweep had exceeded the threshold for impact ionization in a previous measurement. In the proposed model, electrons generated by impact ionization are captured by neutral acceptor trap states in ... |
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| Fabrication and Optical Recombination in III-Nitride Microstructures and Devices |
OCT 2003 |
16 pages |
| Authors:
Hongxing Jiang; Jingyu Lin; KANSAS STATE UNIV MANHATTAN DEPT OF PHYSICS
|
| The research program at Kansas State University is to develop innovative approaches for fabricating high quality III- nitride QWs, heterostructures, microstructures, and micro-devices and to study their optical and optoelectronic properties. By optimizing the epilayer mobilities and optical emission properties, we have produced GaN,Al(x)Ga(1-x)N (x up to 1), In(x)Ga(1- x)N (x<0.3), and In(x)Al( y)Ga(1-x-y)N epilayers, III-nitride QWs with device qualities. We have successfully fabricated micro-size blue emitters and developed a ... |
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| Quantitative Measure for the Nakedness of Fluoride Ion Sources |
23 APR 2003 |
22 pages |
| Authors:
Karl O. Christe; B. Jenkins; ENGINEERING RESEARCH AND CONSULTING INC(ERC INC) EDWARDS AFB CA
|
| A quantitative measure for the donor strength or "nakedness" of fluoride ion donors is presented. It is based on the free energy change associated with the transfer of a fluoride ion from the donor to a given acceptor molecule. Born-Haber cycle calculations were used to calculate both the free energy and enthalpy change for this process. |
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| Small Intercontinental Ballistic Missile (SICBM) Rocket Motor Sympathetic Detonation Study |
10 MAR 2003 |
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| Authors:
Daniel F. Schwartz; Claude E. Merrill; AIR FORCE RESEARCH LAB EDWARDS AFB CA PROPULSION DIRECTORATE WEST
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| The Air Force Research Laboratory (AFRL) Propulsion Directorate at Edwards Air Force Base California utilized two surplus Small Intercontinental Ballistic Missile (SICBM) rocket motors in a sympathetic detonation test with a spacing of 15 feet (4.5 meters) between them (typical max spacing in storage bunkers and transport trailers) to gain technical value from assets deemed undesirable for test firing. The Stage 1 SICBM motor containing 19,200 lbs (8709 kg) of ... |
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| Synthesis and Characterization of the trans-IO2F5(2-) Dianion |
11 FEB 2003 |
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| Authors:
Jerry A. Boatz; William J. Casteel Jr.; Karl O. Christe; David A. Dixon; Michel Gerken; AIR FORCE RESEARCH LAB EDWARDS AFB CA PROPULSION DIRECTORATE WEST
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| The combination of CH3CN solutions of N(CH3)4F and a mixture of cis- and trans-N(CH3)4IO2F4 produces the novel trans-IO2F5(2-) anion. Under the given conditions, only the trans-IO2F4(-) anion acts as a fluoride ion acceptor, thus allowing the separation of isomerically pure, soluble cis-IO2F4(-) from insoluble trans-IO2F5(2-). |
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| Optically Detected Magnetic Resonance of (Effective-Mass) Shallow Acceptors in Si-Doped GaN Homoepitaxial Layers |
01-Jan-2003 |
7 pages |
| Authors:
E R Glaser; Freitas; J A Jr; B V Shanabrook; D D Koleske; S K Lee; S S Park; J Y Han; NAVAL RESEARCH LAB WASHINGTON DC
|
| Optically detected magnetic resonance (ODMR) has been performed on Si-doped GaN homoepitaxial layers grown by organometallic chemical vapor deposition on free-standing GaN templates. In addition to intense excitonic bandedge emission with narrow linewidths (<0.4 meV), these films exhibit strong shallow donor shallow acceptor recombination at 3.27 eV. Most notably, ODMR on this photoluminescence band reveals a highly anisotropic resonance with g|-2.193 +/-0.001 and g|~0 as expected for effective-mass shallow acceptors ... |
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| Silicon Carbide Substrates for GaN Research and Development |
DEC 2002 |
31 pages |
| Authors:
Marek Skowronski; CARNEGIE-MELLON UNIV PITTSBURGH PA DEPT OF MATERIALS SCIENCE AND ENGINEERING
|
| 6H-SiC boules have been grown by physical vapor transport (PVT) method and analyzed using mass spectroscopy (glow discharge and secondary ion) and transport methods. The dominant impurities in crystals grown from commercial SiC charge are nitrogen and boron. Nitrogen concentrations decrease toward the tail while that of boron and aluminum increase. The Fermi level in all crystals started at being pinned to nitrogen donor level in the seed end of ... |
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| Design, Synthesis and Evaluation of Organic Non-linear Optical Chromophores with Configurationally and Conformationally Locked Polyene Bridges |
30 SEP 2002 |
21 pages |
| Authors:
Godson C. Nwokogu; Samuel A. Simpson; HAMPTON UNIV VA DEPT OF CHEMISTRY
|
| A modular, synthetic scheme was developed for versatile variation of donors, acceptors and polyene bridge length of NLO-chromophores. Configurational- and conformational rigidity of the polyene bridges were realized by making each set of adjacent double and single bond pair part of a fused cylohexene ring. Substituent effects on the reactions leading to the establishment of the donor, elongation of the fused polyene bridge and the final introduction of the acceptor ... |
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| Fulvic Acid Oxidation State Detection Using Fluorescence Spectroscopy |
31 AUG 2002 |
5 pages |
| Authors:
Diane McKnight; COLORADO UNIV AT BOULDER INST OF ARCTICAND ALPINE RESEARCH
|
| To investigate and understand the processes by which microorganisms in marine and coastal sediments can use quinone moieties in humic substances as electron acceptors in the degradation of recalcitrant organic material under anoxic conditions. |
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| Materials and Modulators for 3D Displays |
AUG 2002 |
36 pages |
| Authors:
Michael Bass; Alexandra Rapaport; Nabeel Riza; UNIVERSITY OF CENTRAL FLORIDA ORLANDO SCHOOL OF OPTICS/CREOL
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| The research conducted in this program primarily concerned identification of materials that would serve in scalable real time 3D displays. Such materials would have to experience two photon absorption of two different wavelength near infrared beams of light only at the intersection of the two beams. Upon such excitation the material would have to emit visible light. Our focus on scalable materials led us to study organic dyes dissolved in ... |
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| Doping Mechanisms in Wide Bandgap Group III Nitrides |
18 JUL 2002 |
42 pages |
| Authors:
Bruce W. Wessels; NORTHWESTERN UNIV EVANSTON IL MATERIALS SCIENCE CENTER
|
| The role of charge transfer and Fermi level position on impurity solubility, native defect formation and stability in GaN semiconductors was investigated. Several issues were addressed that include: (1) the structure, identity, solubility and stability of intentionally added and unintentional compensating donor defects in p-type and its material, (2) the role hydrogen complexes play in compensating p-type layers, and (3) the role oxygen and Si play in formation of defect ... |
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| Approaches to Advanced Materials for Photorefractive Applications and Radiation Hardening |
01 JUN 2002 |
39 pages |
| Authors:
Seth R. Marder; ARIZONA UNIV TUCSON DEPT OF CHEMISTRY
|
| We have made considerable advances in the development of optical- limiting systems based upon two-photon absorption processes. To accomplish this, it has been essential to develop an understanding of basic structure-property relationships for conjugated organic materials. To this end, we have investigated a range of phenylene-vinylene-based materials substituted with various combinations of donor and acceptor moieties. We now have a more thorough understanding of how to design materials with very ... |
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| Influence of Groundwater Constituents on Longevity of Iron-Based Permeable Barriers |
31 MAY 2002 |
273 pages |
| Authors:
A. L. Roberts; William P. Ball; Peter Searson; Howard Fairbrother; Peter J. Vikesland; JOHNS HOPKINS UNIV BALTIMORE MD
|
| Recent work has demonstrated the utility of iron permeable reactive barriers (PRBs) for the in situ treatment of chlorinated hydrocarbons. In these systems, the surface of the granular iron acts as an electron donor with the reducible contaminant acting as an electron acceptor, thereby leading to corrosion of the material. Although the exact mechanisms involved have not been fully elucidated, field demonstration indicate that the reactions are rapid under environmentally ... |
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| In situ Bioremediation of Perchlorate |
21 MAY 2002 |
175 pages |
| Authors:
ENVIROGEN INC LAWRENCEVILLE NJ
|
| The objective of this project is to develop a biological treatment technology for in situ remediation of perchlorate in subsurface environments. The development of an effective technology for perchlorate remediation requires a fundamental understanding of the conditions that limit biological perchlorate reduction in groundwater and the most effective means to overcome such limitations. This research effort is designed to provide this fundamental understanding. We hypothesize that four key factors may ... |
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| Enhancement of Deep Acceptor Activation in Semiconductors by Superlattice Doping |
04 APR 2002 |
18 pages |
| Authors:
E. F. Schubert; BOSTON UNIV MA COLL OF ENGINEERING
|
| Gallium nitride (GaN) and related compounds are wide bandgap semiconductors suited for high power transistors and many other electronic and optoelectronic devices operating at high frequencies and elevated temperatures. A characteristic of GaN and related compounds is a high activation energy of acceptors, which leads to a low hole concentration in and high p-type resistivity of these materials. The present project proposed and demonstrated a novel approach to the well-known ... |
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| Treatment of Chlorinated Aliphatic Contamination of Groundwater by Horizontal Recirculation Wells and by Constructed Vertical Flow Wetlands |
MAR 2002 |
68 pages |
| Authors:
Michael L. Shelley; Mark N. Goltz; James P. Amon; Abinash Agrawal; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING AND MANAGEMENT
|
| This work explores two innovative technologies for the remediation of chlorinated ethene solvents contaminating groundwater: (1) groundwater circulation wells (GCWs) with downwell zero-valent metal reductive dechlorination reactors, and (2) constructed vertical subsurface flow wetlands. Both the natural dechlorination in wetland sediments, and the engineered dechlorination in a well using zero-valent metals have major implications for the treatment of Air Force pollutants, with the potential to save millions of dollars annually ... |
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| Characterization of Nitrides by Electron Paramagnetic Resonance (EPR) and Optically Detected Magnetic Resonance (ODMR) |
01-Jan-2002 |
11 pages |
| Authors:
E R Glaser; R L Henry; D D Koleske; A E Wickenden; B V Shanabrook; W J Moore; J A Jr; Freitas; G C Braga; W E Carlos; M W Bayerl; NAVAL RESEARCH LAB WASHINGTON DC
|
| We will highlight our recent work on the properties of residual defects and dopants in GaN heteroepitaxial layers and on the nature of recombination from InGaN single quantum well (SQW) light emitting diodes (LEDs) through magnetic resonance techniques. Electron paramagnetic resonance (EPR) and optically detected magnetic resonance (ODMR) were performed on undoped (highly resistive and n-type) and intentionally doped (Si, Mg, or Be) GaN films grown by a variety of ... |
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| Use of Luminescent CdSe-ZnS Nanocrystal Bioconjugates in Quantum Dot-Based Nanosensors |
2002 |
7 pages |
| Authors:
P. T. Tran; E. R. Goldman; G. P. Anderson; J. M. Mauro; H. Mattoussi; NAVAL RESEARCH LAB WASHINGTON DC CENTER FOR BIOMOLECULAR SCIENCE AND ENGINEERING
|
| Biomolecules labeled with luminescent colloidal semiconductor quantum dots (QDs) have potential for use in numerous applications, including fluoro-immunoassays and biological imaging. QD labels exhibit size-tunable narrow-band luminescent emission and high resistance to photodegradation. They also exhibit efficient Fo rster energy transfer between neighboring QDs of different sizes and their emission is readily quenched by bound fluorescent dyes. In this paper, we describe preliminary results aimed at defining conditions for the ... |
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| Role of Sulfation Pharmacogenetics in Breast Cancer Treatment with 2-Methoxyestradiol |
OCT 2001 |
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| Authors:
Araba A. Adjei; MAYO FOUNDATION ROCHESTER MN
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| 2-ME2 is an endogenous estrogen metabolite that inhibits the proliferation of breast and other human cancer cell lines. 2-ME2 also has potent anti-angiogenic and anti-tubulin properties, and it may inhibit estrogen- induced carcinogenesis in the mammary gland. We set out to test the hypothesis that 2-ME2 might be a substrate for sulfate conjugation and, therefore, that individual variations in the sulfation of 2-ME2 might contribute to individual differences in its ... |
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| Shallow Acceptors in Strained MQW Heterostructures in Strong Magnetic Fields |
JUN 2001 |
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| Authors:
V. Ya. Aleshkin; V. I. Gavrilenko; D. B. Veksler; RUSSIAN ACADEMY OF SCIENCES NIZHNY NOVGOROD INSTITUTE FOR PHYSICS OF MICROSTRUCTURES
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| A new nonvariational theoretical technique allowing to calculate both ground and excited states of shallow impurity in a quantum well in the presence of strong magnetic field has been developed. The method has been applied to study the acceptor states in Ge/Ge(1-x)Si(x) MQW heterostructures. The results obtained allow to explain the measured far IR photoconductivity spectra of the heterostructures and to identify the observed spectral lines. |
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| Investigation of Anomalous n-Type Behavior in LWIR MBE-Grown Hg(1-x) Cd(x)Te Using Secondary Ion Mass Spectrometry (SIMS) |
MAR 2001 |
18 pages |
| Authors:
P. R. Boyd; U. Lee; L. A. Almeida; J. D. Benson; ARMY RESEARCH LAB ADELPHI MD
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| Residual impurities and process-introduced electrically active impurities have long been a source of producibility- and performance-related limitations in Hg(1-x)Cd(x)Te materials and devices. Considerable effort has been expended to reduce the impurity content of II-VI substrate materials and to control the level of both donor and acceptor impurities in thin-film sensing layers. In an effort to develop the next major breakthrough in Hg(1-x)Cd(x)Te materials and device technology, the Communications-Electronics Command (CECOM) ... |
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| Photoluminescence of Single Quantum Well Structures in Gallium Arsenide |
MAR 2001 |
76 pages |
| Authors:
Christian A. Bartholomew; AIR FORCE INST OF TECH WRIGHT-PATTERSONAFB OH
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| The continued development of state-of the-art semiconductor technologies and devices by the United States Air Force and the Department of Defense requires accurate and efficient techniques to evaluate and model these new materials. Of particular interest to the Air Force are quantum well structures which can be used for small-scale laser sources in fly-by-light applications, as efficient infrared countermeasures to heat-seeking missiles, or as advanced seekers in optically guided missiles. ... |
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| Magnetic Resonance Studies of Defects in GaN With Reduced Dislocation Densities |
01-Jan-2001 |
8 pages |
| Authors:
E R Glasera; M Leszczynski; R L Henrya; D D Koleskea; A E Wickenden; M E Twigg; W E Carlos; G C Braga; J A Jr; Freitas; I Grzegory; NAVAL RESEARCH LAB WASHINGTON DC
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| Magnetic resonance experiments, including optically detected magnetic resonance (ODMR) and electron paramagnetic resonance (EPR), have been performed on Si-doped homoepitaxial GaN layers grown by MOCVD and on high quality, free-standing (~200 micrometers-thick) GaN grown by HVPE. This allowed us to obtain information on the properties of native defects and dopants in GaN with a significantly reduced density of dislocations (<-10(exp 7)/sq cm) compared to that typically observed (~mid 10(exp 8) ... |
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| Theory of Behavior of Ionized Hydrogen in GaSb Crystal Structure |
2001 |
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| Authors:
Vera Sestakova; Bedrich Stepanek; Jaroslave Sestak; CZECH ACADEMY OF SCIENCES PRAGUE INST OF PHYSICS
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| Using the thermodynamical studies it seems proved that ionized hydrogen acts as amphoteric dopant of GaSb. It is splitting to H(+) (acceptor) and H(-) (donor) and between these two kinds certain equilibrium is created depending on the concentration of acceptor's and donor's impurities in the GaSb material. There is an inclination of such a crystal to maintain the GaSb structure to be isoelectric. This behavior has been studied on undoped ... |
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| Annealing of GaSb Single Crystals in Ionised Hydrogen Atmosphere |
2001 |
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| Authors:
Bedrich Stepanek; Vera Sestakova; Jaroslav Sestak; CZECH ACADEMY OF SCIENCES PRAGUE INST OF PHYSICS
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| GaSb undoped wafer were annealed in flowing ionised hydrogen atmosphere at temperature range between 100 - 350 deg C for 1 - 50 hours. The free carrier concentration and resistivity were measured. It was found out that the wafers being treated at a temperature of 150 deg C for 24 hours reached the resistivity of about 10(exp 2) - 10(exp 3) ohms.cm and the free carrier concentration was lower than ... |
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