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Sample records for density energy-level

  1. Organic semiconductor density of states controls the energy level alignment at electrode interfaces

    PubMed Central

    Oehzelt, Martin; Koch, Norbert; Heimel, Georg

    2014-01-01

    Minimizing charge carrier injection barriers and extraction losses at interfaces between organic semiconductors and metallic electrodes is critical for optimizing the performance of organic (opto-) electronic devices. Here, we implement a detailed electrostatic model, capable of reproducing the alignment between the electrode Fermi energy and the transport states in the organic semiconductor both qualitatively and quantitatively. Covering the full phenomenological range of interfacial energy level alignment regimes within a single, consistent framework and continuously connecting the limiting cases described by previously proposed models allows us to resolve conflicting views in the literature. Our results highlight the density of states in the organic semiconductor as a key factor. Its shape and, in particular, the energy distribution of electronic states tailing into the fundamental gap is found to determine both the minimum value of practically achievable injection barriers as well as their spatial profile, ranging from abrupt interface dipoles to extended band-bending regions. PMID:24938867

  2. Reliable Energy Level Alignment at Physisorbed Molecule–Metal Interfaces from Density Functional Theory

    PubMed Central

    2015-01-01

    A key quantity for molecule–metal interfaces is the energy level alignment of molecular electronic states with the metallic Fermi level. We develop and apply an efficient theoretical method, based on density functional theory (DFT) that can yield quantitatively accurate energy level alignment information for physisorbed metal–molecule interfaces. The method builds on the “DFT+Σ” approach, grounded in many-body perturbation theory, which introduces an approximate electron self-energy that corrects the level alignment obtained from conventional DFT for missing exchange and correlation effects associated with the gas-phase molecule and substrate polarization. Here, we extend the DFT+Σ approach in two important ways: first, we employ optimally tuned range-separated hybrid functionals to compute the gas-phase term, rather than rely on GW or total energy differences as in prior work; second, we use a nonclassical DFT-determined image-charge plane of the metallic surface to compute the substrate polarization term, rather than the classical DFT-derived image plane used previously. We validate this new approach by a detailed comparison with experimental and theoretical reference data for several prototypical molecule–metal interfaces, where excellent agreement with experiment is achieved: benzene on graphite (0001), and 1,4-benzenediamine, Cu-phthalocyanine, and 3,4,9,10-perylene-tetracarboxylic-dianhydride on Au(111). In particular, we show that the method correctly captures level alignment trends across chemical systems and that it retains its accuracy even for molecules for which conventional DFT suffers from severe self-interaction errors. PMID:25741626

  3. Hysteresis in Carbon Nanotube Transistors: Measurement and Analysis of Trap Density, Energy Level, and Spatial Distribution.

    PubMed

    Park, Rebecca Sejung; Shulaker, Max Marcel; Hills, Gage; Suriyasena Liyanage, Luckshitha; Lee, Seunghyun; Tang, Alvin; Mitra, Subhasish; Wong, H-S Philip

    2016-04-26

    We present a measurement technique, which we call the Pulsed Time-Domain Measurement, for characterizing hysteresis in carbon nanotube field-effect transistors, and demonstrate its applicability for a broad range of 1D and 2D nanomaterials beyond carbon nanotubes. The Pulsed Time-Domain Measurement enables the quantification (density, energy level, and spatial distribution) of charged traps responsible for hysteresis. A physics-based model of the charge trapping process for a carbon nanotube field-effect transistor is presented and experimentally validated using the Pulsed Time-Domain Measurement. Leveraging this model, we discover a source of traps (surface traps) unique to devices with low-dimensional channels such as carbon nanotubes and nanowires (beyond interface traps which exist in today's silicon field-effect transistors). The different charge trapping mechanisms for interface traps and surface traps are studied based on their temperature dependencies. Through these advances, we are able to quantify the interface trap density for carbon nanotube field-effect transistors (∼3 × 10(13) cm(-2) eV(-1) near midgap), and compare this against a range of previously studied dielectric/semiconductor interfaces. PMID:27002483

  4. Energy level alignment and quantum conductance of functionalized metal-molecule junctions: Density functional theory versus GW calculations

    SciTech Connect

    Jin, Chengjun; Markussen, Troels; Thygesen, Kristian S.; Strange, Mikkel; Solomon, Gemma C.

    2013-11-14

    We study the effect of functional groups (CH{sub 3}*4, OCH{sub 3}, CH{sub 3}, Cl, CN, F*4) on the electronic transport properties of 1,4-benzenediamine molecular junctions using the non-equilibrium Green function method. Exchange and correlation effects are included at various levels of theory, namely density functional theory (DFT), energy level-corrected DFT (DFT+Σ), Hartree-Fock and the many-body GW approximation. All methods reproduce the expected trends for the energy of the frontier orbitals according to the electron donating or withdrawing character of the substituent group. However, only the GW method predicts the correct ordering of the conductance amongst the molecules. The absolute GW (DFT) conductance is within a factor of two (three) of the experimental values. Correcting the DFT orbital energies by a simple physically motivated scissors operator, Σ, can bring the DFT conductances close to experiments, but does not improve on the relative ordering. We ascribe this to a too strong pinning of the molecular energy levels to the metal Fermi level by DFT which suppresses the variation in orbital energy with functional group.

  5. Energy levels of a heavy ion moving in dense plasmas

    SciTech Connect

    Hu, Hongwei; Chen, Wencong; Zhao, Yongtao; Li, Fuli; Dong, Chenzhong

    2013-12-15

    In this paper, the potential of a slowly moving test particle moving in collisional dense plasmas is studied. It is composed of the Debye-shielding potential, wake potential, and collision term. The Ritz variational-perturbational method is developed for calculating relativistic binding energy levels of a heavy ion moving in dense plasmas. Binding energy levels of a heavy ion moving in plasmas are calculated. The results show that both non-relativistic energy levels and relativistic energy levels become more negative as the temperature becomes high. They also become more negative as the number density decreasing. Relativistic correction is important for calculating binding energy levels. Both relativistic energy levels and non-relativistic energy levels vary minutely as the speed of heavy ion varies.

  6. Theory of Energy Level Tuning in Quantum Dots by Surfactants

    NASA Astrophysics Data System (ADS)

    Zherebetskyy, Danylo; Wang, Lin-Wang; Materials Sciences Division, Lawrence Berkeley National Laboratory Team

    2015-03-01

    Besides quantum confinement that provides control of the quantum dot (QD) band gap, surface ligands allow control of the absolute energy levels. We theoretically investigate energy level tuning in PbS QD by surfactant exchange. We perform direct calculations of real-size QD with various surfactants within the frame of the density functional theory and explicitly analyze the influence of the surfactants on the electronic properties of the QD. This work provides a hint for predictable control of the absolute energy levels and their fine tuning within 3 eV range by modification of big and small surfactants that simultaneously passivate the QD surface.

  7. Temperature dependent energy levels of methylammonium lead iodide perovskite

    SciTech Connect

    Foley, Benjamin J.; Marlowe, Daniel L.; Choi, Joshua J. E-mail: mgupta@virginia.edu; Sun, Keye; Gupta, Mool C. E-mail: mgupta@virginia.edu; Saidi, Wissam A.; Scudiero, Louis E-mail: mgupta@virginia.edu

    2015-06-15

    Temperature dependent energy levels of methylammonium lead iodide are investigated using a combination of ultraviolet photoemission spectroscopy and optical spectroscopy. Our results show that the valence band maximum and conduction band minimum shift down in energy by 110 meV and 77 meV as temperature increases from 28 °C to 85 °C. Density functional theory calculations using slab structures show that the decreased orbital splitting due to thermal expansion is a major contribution to the experimentally observed shift in energy levels. Our results have implications for solar cell performance under operating conditions with continued sunlight exposure and increased temperature.

  8. Energy Levels of Hydrogen and Deuterium

    National Institute of Standards and Technology Data Gateway

    SRD 142 Energy Levels of Hydrogen and Deuterium (Web, free access)   This database provides theoretical values of energy levels of hydrogen and deuterium for principle quantum numbers n = 1 to 200 and all allowed orbital angular momenta l and total angular momenta j. The values are based on current knowledge of the revelant theoretical contributions including relativistic, quantum electrodynamic, recoil, and nuclear size effects.

  9. Energy level transitions of gas in a 2D nanopore

    SciTech Connect

    Grinyaev, Yurii V.; Chertova, Nadezhda V.; Psakhie, Sergei G.

    2015-10-27

    An analytical study of gas behavior in a 2D nanopore was performed. It is shown that the temperature dependence of gas energy can be stepwise due to transitions from one size-quantized subband to another. Taking into account quantum size effects results in energy level transitions governed by the nanopore size, temperature and gas density. This effect leads to an abrupt change of gas heat capacity in the nanopore at the above varying system parameters.

  10. Energy levels for F-16 (Fluorine-16)

    NASA Astrophysics Data System (ADS)

    Sukhoruchkin, S. I.; Soroko, Z. N.

    This document is part of Subvolume C `Tables of Excitations of Proton- and Neutron-rich Unstable Nuclei' of Volume 19 `Nuclear States from Charged Particle Reactions' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms'. It provides energy levels for atomic nuclei of the isotope F-16 (fluorine, atomic number Z = 9, mass number A = 16).

  11. Energy-level alignment at organic heterointerfaces

    PubMed Central

    Oehzelt, Martin; Akaike, Kouki; Koch, Norbert; Heimel, Georg

    2015-01-01

    Today’s champion organic (opto-)electronic devices comprise an ever-increasing number of different organic-semiconductor layers. The functionality of these complex heterostructures largely derives from the relative alignment of the frontier molecular-orbital energies in each layer with respect to those in all others. Despite the technological relevance of the energy-level alignment at organic heterointerfaces, and despite continued scientific interest, a reliable model that can quantitatively predict the full range of phenomena observed at such interfaces is notably absent. We identify the limitations of previous attempts to formulate such a model and highlight inconsistencies in the interpretation of the experimental data they were based on. We then develop a theoretical framework, which we demonstrate to accurately reproduce experiment. Applying this theory, a comprehensive overview of all possible energy-level alignment scenarios that can be encountered at organic heterojunctions is finally given. These results will help focus future efforts on developing functional organic interfaces for superior device performance. PMID:26702447

  12. Automated drawing system of quantum energy levels

    NASA Astrophysics Data System (ADS)

    Stampoultzis, M.; Sinatkas, J.; Tsakstara, V.; Kosmas, T. S.

    2014-03-01

    The purpose of this work is to derive an automated system that provides advantageous drawings of energy spectra for quantum systems (nuclei, atoms, molecules, etc.) required in various physical sciences. The automation involves the development of appropriate computational code and graphical imaging system based on raw data insertion, theoretical calculations and experimental or bibliographic data insertion. The system determines the appropriate scale to depict graphically with the best possible way in the available space. The presently developed code operates locally and the results are displayed on the screen and can be exported to a PostScript file. We note its main features to arrange and visualize in the available space the energy levels with their identity, taking care the existence in the final diagram the least auxiliary deviations. Future improvements can be the use of Java and the availability on the Internet. The work involves the automated plotting of energy levels in molecules, atoms, nuclei and other types of quantized energy spectra. The automation involves the development of an appropriate computational code and graphical imaging system.

  13. Energy level offset analysis of lead atom in laser plasma

    NASA Astrophysics Data System (ADS)

    Zhou, X. M.; Chen, C. S.; Man, B. Y.; Guo, J.; Wang, J.

    2009-08-01

    The optical emission spectra of the plasma generated by a 1064 nm laser irradiation of lead target in air were recorded and analyzed. Temporal evolvement trait of spectral lines was investigated. The Stark width and line shift were measured at different delay time and laser energies. The electron densities were determined using Stark-broadening parameters of spectral lines. The atomic energy level offset in plasma surroundings was explored by analyzing the line shift. The experimental data of Stark widths and line shifts were analyzed using the regularity of the Stark parameters’ dependence on effective ionization potential. However an inverse experimental result was found compared with the theoretical calculation. In addition, the change of the Stark widths and line shifts with the delay time and laser energies was discussed.

  14. Four energy levels device for skin punching

    NASA Astrophysics Data System (ADS)

    Savastru, D.; Ristici, Esofina; Mustata, Marina; Miclos, S.; Rusu, M. I.; Radu, C.; Savu, V.

    2007-03-01

    Generally, the beam distribution in the tissue in interaction with a pulsed laser is defined by optical properties (effective scattering and absorption coefficient). In 2900 nm range, the effective scattering coefficient is much smaller than the absorption coefficient. An Er:YAG skin puncher is presented. Thermal action of a laser beam can be described as one of three types: hyperthermia, coagulation and volatilization, depending on the degree and the duration of tissue heating. We are interested in the volatilization process that means a loss of material. The various constituents of the tissue disappear in smoke at above 100 0C in a relatively short time of around one tenth of a second. At the edges of the volatilization zone there is a region of coagulation necrosis. In presented case of an Er:YAG laser operating in a free generation mode, the mechanical effects can result from explosive vaporization. When the exposure time of the laser is lower than the characteristic time of the thermal diffusion in the tissue, it produces a thermal containment with an accumulation of heat without diffusion and an explosive vaporization of the target. The Er:YAG laser device has the pulse length of about 160 microseconds and four emitted energy levels. This device is used to punch the skin for blood sampling for different kinds of analysis. The front panel of the device has four keys to select the desired energy according to the skin type.

  15. "Piekara's Chair": Mechanical Model for Atomic Energy Levels.

    ERIC Educational Resources Information Center

    Golab-Meyer, Zofia

    1991-01-01

    Uses the teaching method of models or analogies, specifically the model called "Piekara's chair," to show how teaching classical mechanics can familiarize students with the notion of energy levels in atomic physics. (MDH)

  16. Housing Electrons: Relating Quantum Numbers, Energy Levels, and Electron Configurations.

    ERIC Educational Resources Information Center

    Garofalo, Anthony

    1997-01-01

    Presents an activity that combines the concepts of quantum numbers and probability locations, energy levels, and electron configurations in a concrete, hands-on way. Uses model houses constructed out of foam board and colored beads to represent electrons. (JRH)

  17. Revised energy levels and hyperfine structure constants of Ta II

    NASA Astrophysics Data System (ADS)

    Windholz, Laurentius; Arcimowicz, Bronislaw; Uddin, Zaheer

    2016-06-01

    Using a wave number calibrated Fourier transform spectrum, we determined the energy levels of the first ion of tantalum with high accuracy. To get the correct center of gravity wave numbers of the observed spectral lines, the knowledge of the hyperfine constants of the involved levels was necessary. From the observed values we deduced the energy levels in a global fit. A comparison between our results and all available literature values is presented.

  18. Calculation of Rydberg energy levels for the francium atom

    NASA Astrophysics Data System (ADS)

    Huang, Shi-Zhong; Chu, Jin-Min

    2010-06-01

    Based on the weakest bound electron potential model theory, the Rydberg energy levels and quantum defects of the np2Po1/2 (n = 7-50) and np2Po3/2 (n = 7-50) spectrum series for the francium atom are calculated. The calculated results are in excellent agreement with the 48 measured levels, and 40 energy levels for highly excited states are predicted.

  19. Energy level realignment in weakly interacting donor-acceptor binary molecular networks.

    PubMed

    Zhong, Jian-Qiang; Qin, Xinming; Zhang, Jia-Lin; Kera, Satoshi; Ueno, Nobuo; Wee, Andrew Thye Shen; Yang, Jinlong; Chen, Wei

    2014-02-25

    Understanding the effect of intermolecular and molecule-substrate interactions on molecular electronic states is key to revealing the energy level alignment mechanism at organic-organic heterojunctions or organic-inorganic interfaces. In this paper, we investigate the energy level alignment mechanism in weakly interacting donor-acceptor binary molecular superstructures, comprising copper hexadecafluorophthalocyanine (F16CuPc) intermixed with copper phthalocyanine (CuPc), or manganese phthalocynine (MnPc) on graphite. The molecular electronic structures have been systematically studied by in situ ultraviolet photoelectron spectroscopy (UPS) and low-temperature scanning tunneling microscopy/spectroscopy (LT-STM/STS) experiments and corroborated by density functional theory (DFT) calculations. As demonstrated by the UPS and LT-STM/STS measurements, the observed unusual energy level realignment (i.e., a large downward shift in donor HOMO level and a corresponding small upward shift in acceptor HOMO level) in the CuPc-F16CuPc binary superstructures originates from the balance between intermolecular and molecule-substrate interactions. The enhanced intermolecular interactions through the hydrogen bonding between neighboring CuPc and F16CuPc can stabilize the binary superstructures and modify the local molecular electronic states. The obvious molecular energy level shift was explained by gap-state-mediated interfacial charge transfer. PMID:24433044

  20. Energy level modification in lead sulfide quantum dot thin films through ligand exchange.

    PubMed

    Brown, Patrick R; Kim, Donghun; Lunt, Richard R; Zhao, Ni; Bawendi, Moungi G; Grossman, Jeffrey C; Bulović, Vladimir

    2014-06-24

    The electronic properties of colloidal quantum dots (QDs) are critically dependent on both QD size and surface chemistry. Modification of quantum confinement provides control of the QD bandgap, while ligand-induced surface dipoles present a hitherto underutilized means of control over the absolute energy levels of QDs within electronic devices. Here, we show that the energy levels of lead sulfide QDs, measured by ultraviolet photoelectron spectroscopy, shift by up to 0.9 eV between different chemical ligand treatments. The directions of these energy shifts match the results of atomistic density functional theory simulations and scale with the ligand dipole moment. Trends in the performance of photovoltaic devices employing ligand-modified QD films are consistent with the measured energy level shifts. These results identify surface-chemistry-mediated energy level shifts as a means of predictably controlling the electronic properties of colloidal QD films and as a versatile adjustable parameter in the performance optimization of QD optoelectronic devices. PMID:24824726

  1. Calibration of Electric Field Induced Energy Level Shifts in Argon

    NASA Astrophysics Data System (ADS)

    Hebner, Greg

    1999-10-01

    Argon is a commonly used gas in a number of discharges. As such it is an ideal candidate for spectroscopic based electric field measurements within the sheath and bulk discharge regions. Recently, measurements demonstrated the use of the Stark induced shifts of high lying energy levels in Argon to make spatially and temporally resolved electric field measurements [1]. However, that method relied on the cross calibration of known and calculable shifts in helium discharges to calibrate, in-situ, the energy level shifts in Argon. This poster shows the use of an atomic beam system to calibrate the electric field induced shift of high lying energy levels directly. In addition, data on very high lying argon levels, up to the 20 F manifold, were obtained. Comparison of our electric field induced energy level shift calibration curves with previous work will be shown. The possibility of using this system to calibrate energy level shifts in other gases of technological interest to the microelectronics and lighting industry will be discussed. [1]. J. B. Kim, K. Kawamura, Y. W. Choi, M. D. Bowden, K. Muraoka and V. Helbig, IEEE Transactions on Plasma Science, 26(5), 1556 (1998). This work was performed at Sandia National Laboratories and supported by the United States Department of Energy (DE-AC04-94AL85000).

  2. Electronic energy levels of intermediates in the laboratory

    NASA Astrophysics Data System (ADS)

    Howard, I. A.; Horlick, G.

    1980-12-01

    Using the multiple scattering X-alpha method, electronic energy levels have been found self-consistently for the intermediates Ni(CO)(n), n = 1,2,3 in the formation of nickel tetracarbonyl via the Ni-CO surface reaction. Linear geometries have been assumed for NiCO and Ni(CO)2, and a trigonal planar conformation for Ni(CO)3, in accordance with previously published IR spectra. The intermediates were assumed to be in the gas phase, free of surface interaction. From the energy level structure found, all three of the intermediates were determined to be diamagnetic, as Ni(CO)4 is known to be.

  3. Electronic energy levels of intermediates in the nickel carbonylation reaction

    NASA Astrophysics Data System (ADS)

    Howard, I. A.; Pratt, G. W.; Johnson, K. H.; Dresselhaus, G.

    1981-03-01

    Using the multiple scattering Xa method, electronic energy levels have been found self-consistently for the intermediates Ni(CO)n, n = 1,2,3 in the formation of nickel tetracarbonyl via the Ni-CO surface reaction. Linear geometries have been assumed for NiCO and Ni(CO)2, and a trigonal planar conformation for Ni(CO)3, in accordance with previously published IR spectra. The intermediates were assumed to be in the gas phase, free of surface interaction. From the energy level structure found, all three of the intermediates were determined to be diamagnetic, as Ni(CO)4 is known to be.

  4. First-principles approach to calculating energy level alignment at aqueous semiconductor interfaces

    DOE PAGESBeta

    Kharche, Neerav; Muckerman, James T.; Hybertsen, Mark S.

    2014-10-21

    A first-principles approach is demonstrated for calculating the relationship between an aqueous semiconductor interface structure and energy level alignment. The physical interface structure is sampled using density functional theory based molecular dynamics, yielding the interface electrostatic dipole. The GW approach from many-body perturbation theory is used to place the electronic band edge energies of the semiconductor relative to the occupied 1b₁ energy level in water. The application to the specific cases of nonpolar (101¯0 ) facets of GaN and ZnO reveals a significant role for the structural motifs at the interface, including the degree of interface water dissociation and themore » dynamical fluctuations in the interface Zn-O and O-H bond orientations. As a result, these effects contribute up to 0.5 eV.« less

  5. First-principles approach to calculating energy level alignment at aqueous semiconductor interfaces

    SciTech Connect

    Kharche, Neerav; Muckerman, James T.; Hybertsen, Mark S.

    2014-10-21

    A first-principles approach is demonstrated for calculating the relationship between an aqueous semiconductor interface structure and energy level alignment. The physical interface structure is sampled using density functional theory based molecular dynamics, yielding the interface electrostatic dipole. The GW approach from many-body perturbation theory is used to place the electronic band edge energies of the semiconductor relative to the occupied 1benergy level in water. The application to the specific cases of nonpolar (101¯0 ) facets of GaN and ZnO reveals a significant role for the structural motifs at the interface, including the degree of interface water dissociation and the dynamical fluctuations in the interface Zn-O and O-H bond orientations. As a result, these effects contribute up to 0.5 eV.

  6. Magnetic field dependence of energy levels in biased bilayer graphene quantum dots

    NASA Astrophysics Data System (ADS)

    da Costa, D. R.; Zarenia, M.; Chaves, Andrey; Farias, G. A.; Peeters, F. M.

    2016-02-01

    Using the tight-binding approach, we study the influence of a perpendicular magnetic field on the energy levels of hexagonal, triangular, and circular bilayer graphene (BLG) quantum dots (QDs) with zigzag and armchair edges. We obtain the energy levels for AB (Bernal)-stacked BLG QDs in both the absence and the presence of a perpendicular electric field (i.e., biased BLG QDs). We find different regions in the spectrum of biased QDs with respect to the crossing point between the lowest-electron and -hole Landau levels of a biased BLG sheet. Those different regions correspond to electron states that are localized at the center, edge, or corner of the BLG QD. Quantum Hall corner states are found to be absent in circular BLG QDs. The spatial symmetry of the carrier density distribution is related to the symmetry of the confinement potential, the position of zigzag edges, and the presence or absence of interlayer inversion symmetry.

  7. Degeneracy of energy levels of pseudo-Gaussian oscillators

    SciTech Connect

    Iacob, Theodor-Felix; Iacob, Felix; Lute, Marina

    2015-12-07

    We study the main features of the isotropic radial pseudo-Gaussian oscillators spectral properties. This study is made upon the energy levels degeneracy with respect to orbital angular momentum quantum number. In a previous work [6] we have shown that the pseudo-Gaussian oscillators belong to the class of quasi-exactly solvable models and an exact solution has been found.

  8. Efficiencies of thermodynamics when temperature-dependent energy levels exist.

    PubMed

    Yamano, Takuya

    2016-03-14

    Based on a generalized form of the second law of thermodynamics, in which the temperature-dependent energy levels of a system are appropriately included in entropy generation, we show that the effect reasonably appears in efficiencies of thermodynamic processes. PMID:26890276

  9. Energy Level Alignment at Aqueous GaN and ZnO Interfaces

    NASA Astrophysics Data System (ADS)

    Hybertsen, Mark S.; Kharche, Neerav; Muckerman, James T.

    2014-03-01

    Electronic energy level alignment at semiconductor-electrolyte interfaces is fundamental to electrochemical activity. Motivated in particular by the search for new materials that can be more efficient for photocatalysis, we develop a first principles method to calculate this alignment at aqueous interfaces and demonstrate it for the specific case of non-polar GaN and ZnO interfaces with water. In the first step, density functional theory (DFT) based molecular dynamics is used to sample the physical interface structure and to evaluate the electrostatic potential step at the interface. In the second step, the GW approach is used to evaluate the reference electronic energy level separately in the bulk semiconductor (valence band edge energy) and in bulk water (the 1b1 energy level), relative to the internal electrostatic energy reference. Use of the GW approach naturally corrects for errors inherent in the use of Kohn-Sham energy eigenvalues to approximate the electronic excitation energies in each material. With this predicted interface alignment, specific redox levels in water, with potentials known relative to the 1b1 level, can then be compared to the semiconductor band edge positions. Our results will be discussed in the context of experiments in which photoexcited GaN and ZnO drive the hydrogen evolution reaction. Research carried out at Brookhaven National Laboratory under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.

  10. Energy levels of hybrid monolayer-bilayer graphene quantum dots

    NASA Astrophysics Data System (ADS)

    Mirzakhani, M.; Zarenia, M.; Ketabi, S. A.; da Costa, D. R.; Peeters, F. M.

    2016-04-01

    Often real samples of graphene consist of islands of both monolayer and bilayer graphene. Bound states in such hybrid quantum dots are investigated for (i) a circular single-layer graphene quantum dot surrounded by an infinite bilayer graphene sheet and (ii) a circular bilayer graphene quantum dot surrounded by an infinite single-layer graphene. Using the continuum model and applying zigzag boundary conditions at the single-layer-bilayer graphene interface, we obtain analytical results for the energy levels and the corresponding wave spinors. Their dependence on perpendicular magnetic and electric fields are studied for both types of quantum dots. The energy levels exhibit characteristics of interface states, and we find anticrossings and closing of the energy gap in the presence of a bias potential.

  11. Energy levels scheme simulation of divalent cobalt doped bismuth germanate

    SciTech Connect

    Andreici, Emiliana-Laura; Petkova, Petya; Avram, Nicolae M.

    2015-12-07

    The aim of this paper is to simulate the energy levels scheme for Bismuth Germanate (BGO) doped with divalent cobalt, in order to give a reliable explanation for spectral experimental data. In the semiempirical crystal field theory we first modeled the Crystal Field Parameters (CFPs) of BGO:Cr{sup 2+} system, in the frame of Exchange Charge Model (ECM), with actually site symmetry of the impurity ions after doping. The values of CFPs depend on the geometry of doped host matrix and by parameter G of ECM. First, we optimized the geometry of undoped BGO host matrix and afterwards, that of doped BGO with divalent cobalt. The charges effect of ligands and covalence bonding between cobalt cations and oxygen anions, in the cluster approach, also were taken into account. With the obtained values of the CFPs we simulate the energy levels scheme of cobalt ions, by diagonalizing the matrix of the doped crystal Hamiltonian. Obviously, energy levels and estimated Racah parameters B and C were compared with the experimental spectroscopic data and discussed. Comparison of obtained results with experimental data shows quite satisfactory, which justify the model and simulation schemes used for the title system.

  12. Energy levels, lifetimes and radiative data of Ba XXVI

    NASA Astrophysics Data System (ADS)

    Singh, A. K.; Goyal, Arun; Khatri, Indu; Aggarwal, Sunny; Sharma, Rinku; Mohan, Man

    2016-05-01

    We report an extensive and an elaborate theoretical study of atomic data for Ba XXVI by considering Singlet, Doublet and Triplet (SDT) electron excitations within N-shell and single excitations from N-shell to O-shell. We have calculated energy levels and lifetimes for lowest 110 fine structure levels by using Multi-configuration Dirac-Fock method (MCDF). We have also considered Quantum Electrodynamics (QED) and Breit corrections in our calculations. We have presented the radiative data for electric and magnetic dipole (E1, M1) and quadrupole (E2, M2) transitions among lowest 110 levels. We have made comparisons of our calculated excitation energies and EUV (Extreme Ultraviolet) transition wavelengths with experimentally observed energy levels and wavelengths and achieved good agreement. We have also computed energy levels by performing similar relativistic distorted wave calculations using Flexible Atomic Code (FAC). Additionally, we have provided new atomic data for Ba XXVI which are not published elsewhere in the literature. We believe that our results may be beneficial in fusion plasma research and astrophysical investigations and applications.

  13. S-matrix calculations of energy levels of alkalilike ions

    NASA Astrophysics Data System (ADS)

    Sapirstein, Jonathan; Cheng, K. T.

    2013-05-01

    A recent S-matrix based QED calculation of energy levels of the lithium isoelectronic sequence is extended to the general case of a valence electron outside an arbitrary filled core. Formulas are presented that allow calculation of the energy levels of valence ns , np1 / 2 , np3 / 2 , nd3 / 2 , and nd5 / 2 states. Emphasis is placed on modifications of the lithiumlike formulas required because more than one core state is present, and a discussion of an unusual feature of the two-photon exchange contribution involving autoiononizing states is given. The method is illustrated with a calculation of energy levels of the sodium isoelectronic sequence, with results for 3s1 / 2 , 3p1 / 2 , and 3p3 / 2 energies tabulated for the range Z = 20 - 100 . A detailed breakdown of the calculation is given for Z = 74 . Comparison with experiment and other calculations is given, and prospects for extension of the method to ions with more complex electronic structure discussed. The work of JS was supported in part by NSF Grant No. PHY-1068065. The work of KTC was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

  14. New Fe ii energy levels from stellar spectra

    NASA Astrophysics Data System (ADS)

    Castelli, F.; Kurucz, R. L.

    2010-09-01

    Aims: The spectra of B-type and early A-type stars show numerous unidentified lines in the whole optical range, especially in the 5100-5400 Å interval. Because Fe ii transitions to high energy levels should be observed in this region, we used semiempirical predicted wavelengths and gf-values of Fe ii to identify unknown lines. Methods: Semiempirical line data for Fe ii computed by Kurucz are used to synthesize the spectrum of the slow-rotating, Fe-overabundant CP star HR 6000. Results: We determined a total of 109 new 4f levels for Fe ii with energies ranging from 122 324 cm-1 to 128 110 cm-1. They belong to the Fe ii subconfigurations 3d6(3P)4f (10 levels), 3d6(3H)4f (36 levels), 3d6(3F)4f (37 levels), and 3d6(3G)4f (26 levels). We also found 14 even levels from 4d (3 levels), 5d (7 levels), and 6d (4 levels) configurations. The new levels have allowed us to identify more than 50% of the previously unidentified lines of HR 6000 in the wavelength region 3800-8000 Å. Tables listing the new energy levels are given in the paper; tables listing the spectral lines with log gf ≥ -1.5 that are transitions to the 4f energy levels are given in the Online Material. These new levels produce 18 000 lines throughout the spectrum from the ultraviolet to the infrared. Tables 6-9 are also available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/520/A57

  15. Energy levels of double triangular graphene quantum dots

    SciTech Connect

    Liang, F. X.; Jiang, Z. T. Zhang, H. Y.; Li, S.; Lv, Z. T.

    2014-09-28

    We investigate theoretically the energy levels of the coupled double triangular graphene quantum dots (GQDs) based on the tight-binding Hamiltonian model. The double GQDs including the ZZ-type, ZA-type, and AA-type GQDs with the two GQDs having the zigzag or armchair boundaries can be coupled together via different interdot connections, such as the direct coupling, the chains of benzene rings, and those of carbon atoms. It is shown that the energy spectrum of the coupled double GQDs is the amalgamation of those spectra of the corresponding two isolated GQDs with the modification triggered by the interdot connections. The interdot connection is inclined to lift up the degeneracies of the energy levels in different degree, and as the connection changes from the direct coupling to the long chains, the removal of energy degeneracies is suppressed in ZZ-type and AA-type double GQDs, which indicates that the two coupled GQDs are inclined to become decoupled. Then we consider the influences on the spectra of the coupled double GQDs induced by the electric fields applied on the GQDs or the connection, which manifests as the global spectrum redistribution or the local energy level shift. Finally, we study the symmetrical and asymmetrical energy spectra of the double GQDs caused by the substrates supporting the two GQDs, clearly demonstrating how the substrates affect the double GQDs' spectrum. This research elucidates the energy spectra of the coupled double GQDs, as well as the mechanics of manipulating them by the electric field and the substrates, which would be a significant reference for designing GQD-based devices.

  16. Energy level alignment in Au/pentacene/PTCDA trilayer stacks

    NASA Astrophysics Data System (ADS)

    Sehati, P.; Braun, S.; Fahlman, M.

    2013-09-01

    Ultraviolet photoelectron spectroscopy is used to investigate the energy level alignment and molecular orientation at the interfaces in Au/pentacene/PTCDA trilayer stacks. We deduced a standing orientation for pentacene grown on Au while we conclude a flat lying geometry for PTCDA grown onto pentacene. We propose that the rough surface of polycrystalline Au induces the standing geometry in pentacene. It is further shown that in situ deposition of PTCDA on pentacene can influence the orientation of the surface pentacene layer, flipping part of the surface pentacene molecules into a flat lying geometry, maximizing the orbital interaction across the pentacene-PTCDA heterojunction.

  17. Accurate energy levels for singly ionized platinum (Pt II)

    NASA Technical Reports Server (NTRS)

    Reader, Joseph; Acquista, Nicolo; Sansonetti, Craig J.; Engleman, Rolf, Jr.

    1988-01-01

    New observations of the spectrum of Pt II have been made with hollow-cathode lamps. The region from 1032 to 4101 A was observed photographically with a 10.7-m normal-incidence spectrograph. The region from 2245 to 5223 A was observed with a Fourier-transform spectrometer. Wavelength measurements were made for 558 lines. The uncertainties vary from 0.0005 to 0.004 A. From these measurements and three parity-forbidden transitions in the infrared, accurate values were determined for 28 even and 72 odd energy levels of Pt II.

  18. Energy level modeling of lanthanide materials: review and uncertainty analysis.

    PubMed

    Joos, Jonas J; Poelman, Dirk; Smet, Philippe F

    2015-07-15

    Energy level schemes are an essential tool for the description and interpretation of atomic spectra. During the last 40 years, several empirical methods and relationships were devised for constructing energy level schemes of lanthanide defects in wide band gap solids, culminating in the chemical shift model by Thiel and Dorenbos. This model allows us to calculate the electronic and optical properties of the considered materials. However, an unbiased assessment of the accuracy of the obtained values of the calculated parameters is still lacking to a large extent. In this paper, error margins for calculated electronic and optical properties are deduced. It is found that optical transitions can be predicted within an acceptable error margin, while the description of phenomena involving conduction band states is limited to qualitative interpretation due to the large error margins for physical observables such as thermal quenching temperature, corresponding to standard deviations in the range 0.3-0.5 eV for the relevant energy differences. As an example, the electronic structure of lanthanide doped calcium thiogallate (CaGa2S4) is determined, taking the experimental spectra of CaGa2S4:Ln(Q+) (Ln(Q+) = Ce(3+), Eu(2+), Tm(3+)) as input. Two different approaches to obtain the shape of the zig-zag curves connecting the 4f levels of the different lanthanides are explored and compared. PMID:26129935

  19. Energy level control: toward an efficient hot electron transport

    PubMed Central

    Jin, Xiao; Li, Qinghua; Li, Yue; Chen, Zihan; Wei, Tai-Huei; He, Xingdao; Sun, Weifu

    2014-01-01

    Highly efficient hot electron transport represents one of the most important properties required for applications in photovoltaic devices. Whereas the fabrication of efficient hot electron capture and lost-cost devices remains a technological challenge, regulating the energy level of acceptor-donor system through the incorporation of foreign ions using the solution-processed technique is one of the most promising strategies to overcome this obstacle. Here we present a versatile acceptor-donor system by incorporating MoO3:Eu nanophosphors, which reduces both the ‘excess' energy offset between the conduction band of acceptor and the lowest unoccupied molecular orbital of donor, and that between the valence band and highest occupied molecular orbital. Strikingly, the hot electron transfer time has been shortened. This work demonstrates that suitable energy level alignment can be tuned to gain the higher hot electron/hole transport efficiency in a simple approach without the need for complicated architectures. This work builds up the foundation of engineering building blocks for third-generation solar cells. PMID:25099864

  20. Calculation of Electrochemical Energy Levels in Water Using the Random Phase Approximation and a Double Hybrid Functional

    NASA Astrophysics Data System (ADS)

    Cheng, Jun; VandeVondele, Joost

    2016-02-01

    Understanding charge transfer at electrochemical interfaces requires consistent treatment of electronic energy levels in solids and in water at the same level of the electronic structure theory. Using density-functional-theory-based molecular dynamics and thermodynamic integration, the free energy levels of six redox couples in water are calculated at the level of the random phase approximation and a double hybrid density functional. The redox levels, together with the water band positions, are aligned against a computational standard hydrogen electrode, allowing for critical analysis of errors compared to the experiment. It is encouraging that both methods offer a good description of the electronic structures of the solutes and water, showing promise for a full treatment of electrochemical interfaces.

  1. Calculation of Electrochemical Energy Levels in Water Using the Random Phase Approximation and a Double Hybrid Functional.

    PubMed

    Cheng, Jun; VandeVondele, Joost

    2016-02-26

    Understanding charge transfer at electrochemical interfaces requires consistent treatment of electronic energy levels in solids and in water at the same level of the electronic structure theory. Using density-functional-theory-based molecular dynamics and thermodynamic integration, the free energy levels of six redox couples in water are calculated at the level of the random phase approximation and a double hybrid density functional. The redox levels, together with the water band positions, are aligned against a computational standard hydrogen electrode, allowing for critical analysis of errors compared to the experiment. It is encouraging that both methods offer a good description of the electronic structures of the solutes and water, showing promise for a full treatment of electrochemical interfaces. PMID:26967430

  2. Energy levels and radiative transition rates for Ba XLVIII

    NASA Astrophysics Data System (ADS)

    Khatri, Indu; Goyal, Arun; Aggarwal, Sunny; Singh, A. K.; Mohan, Man

    2016-01-01

    Energy levels and radiative rates are reported for transitions in F-like Ba XLVIII. Configuration interaction has been included among 27 configurations (generating 431 levels) over a wide energy range up to 618 Rydbergs, and the fully relativistic multi-configurational Dirac-Fock method adopted for the calculations. To assess the accuracy, calculations have also been performed with the flexible atomic code, FAC. Radiative rates, oscillator strengths and line strengths are reported for all electric dipole, magnetic dipole, electric quadrupole, and magnetic quadrupole transitions from the lowest 3 levels, although calculations have been performed for a much larger number of levels. We have made comparisons of our results with existing available results and a good agreement has been achieved. Additionally, lifetimes for all 431 levels are listed.

  3. Electron Energy Levels in the 1D-2D Transition

    NASA Astrophysics Data System (ADS)

    Pepper, Michael; Sanjeev, Kumar; Thomas, Kalarikad; Creeth, Graham; English, David; Ritchie, David; Griffiths, Jonathan; Farrer, Ian; Jones, Geraint

    Using GaAs-AlGaAs heterostructures we have investigated the behaviour of electron energy levels with relaxation of the potential confining a 2D electron gas into a 1D configuration. In the ballistic regime of transport, when the conductance shows quantized plateaux, different types of behaviour are found according to the spins of interacting levels, whether a magnetic field is applied and lifting of the momentum degeneracy with a source-drain voltage. We have observed both crossing and anti-crossing of levels and have investigated the manner in which they can be mutually converted. In the presence of a magnetic field levels can cross and lock together as the confinement is altered in a way which is characteristic of parallel channels. The overall behaviour is discussed in terms of electron interactions and the wavefunction flexibility allowed by the increasing two dimensionality of the electron distribution as the confinement is weakened. Work supported by UK EPSRC.

  4. Efficient light emission from inorganic and organic semiconductor hybrid structures by energy-level tuning

    PubMed Central

    Schlesinger, R.; Bianchi, F.; Blumstengel, S.; Christodoulou, C.; Ovsyannikov, R.; Kobin, B.; Moudgil, K.; Barlow, S.; Hecht, S.; Marder, S.R.; Henneberger, F.; Koch, N.

    2015-01-01

    The fundamental limits of inorganic semiconductors for light emitting applications, such as holographic displays, biomedical imaging and ultrafast data processing and communication, might be overcome by hybridization with their organic counterparts, which feature enhanced frequency response and colour range. Innovative hybrid inorganic/organic structures exploit efficient electrical injection and high excitation density of inorganic semiconductors and subsequent energy transfer to the organic semiconductor, provided that the radiative emission yield is high. An inherent obstacle to that end is the unfavourable energy level offset at hybrid inorganic/organic structures, which rather facilitates charge transfer that quenches light emission. Here, we introduce a technologically relevant method to optimize the hybrid structure's energy levels, here comprising ZnO and a tailored ladder-type oligophenylene. The ZnO work function is substantially lowered with an organometallic donor monolayer, aligning the frontier levels of the inorganic and organic semiconductors. This increases the hybrid structure's radiative emission yield sevenfold, validating the relevance of our approach. PMID:25872919

  5. Efficient light emission from inorganic and organic semiconductor hybrid structures by energy-level tuning

    NASA Astrophysics Data System (ADS)

    Schlesinger, R.; Bianchi, F.; Blumstengel, S.; Christodoulou, C.; Ovsyannikov, R.; Kobin, B.; Moudgil, K.; Barlow, S.; Hecht, S.; Marder, S. R.; Henneberger, F.; Koch, N.

    2015-04-01

    The fundamental limits of inorganic semiconductors for light emitting applications, such as holographic displays, biomedical imaging and ultrafast data processing and communication, might be overcome by hybridization with their organic counterparts, which feature enhanced frequency response and colour range. Innovative hybrid inorganic/organic structures exploit efficient electrical injection and high excitation density of inorganic semiconductors and subsequent energy transfer to the organic semiconductor, provided that the radiative emission yield is high. An inherent obstacle to that end is the unfavourable energy level offset at hybrid inorganic/organic structures, which rather facilitates charge transfer that quenches light emission. Here, we introduce a technologically relevant method to optimize the hybrid structure's energy levels, here comprising ZnO and a tailored ladder-type oligophenylene. The ZnO work function is substantially lowered with an organometallic donor monolayer, aligning the frontier levels of the inorganic and organic semiconductors. This increases the hybrid structure's radiative emission yield sevenfold, validating the relevance of our approach.

  6. Energy levels and transition probability matrix elements of ruby for maser applications

    NASA Technical Reports Server (NTRS)

    Berwin, R. W.

    1971-01-01

    Program computes fine structure energy levels of ruby as a function of magnetic field. Included in program is matrix formulation, each row of which contains a magnetic field and four corresponding energy levels.

  7. Interaction Determined Electron Energy Levels in One-Dimension

    NASA Astrophysics Data System (ADS)

    Pepper, Michael; Kumar, Sanjeev; Thomas, Kalarikad; Smith, Luke; Creeth, Graham; Farrer, Ian; Ritchie, David; Jones, Geraint; Jonathan, Griffiths; UCL Collaboration; Cavendish Laboratory Collaboration

    2015-03-01

    We have investigated electron transport in a quasi-one dimensional electron gas in the GaAs-AlGaAs heterostructure designed so that the confinement potential can be progressively weakened. This causes the energy levels to decrease in energy relative to each other, however this decrease occurs at different rates, a feature attributed to the energy being determined by both confinement and the electron-electron repulsion which varies with the shape of the wavefunction. It is found that the initial ground state crosses the higher levels so resulting in missing plateaux of quantised conductance. A change in the nature of the ground state to a more extended form causes an increase in the capacitance between the confining gates and the electrons. Both crossings and anti-crossings of the levels are found and these will be discussed along with other consequences of the form of the level interactions. The effects of level crossing on the spin dependent 0.7 structure will be presented. Supported by EPSRC (UK).

  8. Energy levels and transition rates for helium-like ions with Z = 10-36

    NASA Astrophysics Data System (ADS)

    Si, R.; Guo, X. L.; Wang, K.; Li, S.; Yan, J.; Chen, C. Y.; Brage, T.; Zou, Y. M.

    2016-08-01

    Aims: Helium-like ions provide an important X-ray spectral diagnostics in astrophysical and high-temperature fusion plasmas. An interpretation of the observed spectra provides information on temperature, density, and chemical compositions of the plasma. Such an analysis requires information for a wide range of atomic parameters, including energy levels and transition rates. Our aim is to provide a set of accurate energy levels and transition rates for helium-like ions with Z = 10-36. Methods: The second-order many-body perturbation theory (MBPT) was adopted in this paper. To support our MBPT results, we performed an independent calculation using the multiconfiguration Dirac-Hartree-Fock (MCDHF) method. Results: We provide accurate energies for the lowest singly excited 70 levels among 1snl(n ≤ 6,l ≤ (n-1)) configurations and the lowest doubly excited 250 levels arising from the K-vacancy 2ln'l'(n' ≤ 6,l' ≤ (n'-1)) configurations of helium-like ions with Z = 10-36. Wavelengths, transition rates, oscillator strengths, and line strengths are calculated for the E1, M1, E2, and M2 transitions among these levels. The radiative lifetimes are reported for all the calculated levels. Conclusions: Our MBPT results for singly excited n ≤ 2 levels show excellent agreement with other elaborate calculations, while those for singly excited n ≥ 3 and doubly excited levels show significant improvements over previous theoretical results. Our results will be very helpful for astrophysical line identification and plasma diagnostics. Full Tables 1 and 2 are only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/592/A141

  9. First-Principles Approach to Energy Level Alignment at Aqueous Semiconductor Interfaces

    NASA Astrophysics Data System (ADS)

    Hybertsen, Mark

    2015-03-01

    We have developed a first principles method to calculate the energy level alignment between semiconductor band edges and reference energy levels at aqueous interfaces. This alignment is fundamental to understand the electrochemical characteristics of any semiconductor electrode in general and the potential for photocatalytic activity in particular. For example, in the search for new photo-catalytic materials, viable candidates must demonstrate both efficient absorption of the solar spectrum and an appropriate alignment of the band edge levels in the semiconductor to the redox levels for the target reactions. In our approach, the interface-specific contribution to the electrostatic step across the interface is evaluated using density functional theory (DFT) based molecular dynamics to sample the physical interface structure and the corresponding change in the electrostatic potential at the interface. The reference electronic levels in the semiconductor and in the water are calculated using the GW approach, which naturally corrects for errors inherent in the use of Kohn-Sham energy eigenvalues to approximate the electronic excitation energies in each material. Taken together, our calculations provide the alignment of the semiconductor valence band edge to the centroid of the highest occupied 1b1 level in water. The known relationship of the 1b1 level to the normal hydrogen electrode completes the connection to electrochemical levels. We discuss specific results for GaN, ZnO, and TiO2. The effect of interface structural motifs, such as different degrees of water dissociation, and of dynamical characteristics, will be presented together with available experimental data. Work supported by the US Department of Energy, Office of Basic Energy Sciences under Contract No. DE-AC02-98CH10886.

  10. Energy levels and the de Broglie relationship for high school students

    NASA Astrophysics Data System (ADS)

    Gianino, Concetto

    2008-07-01

    In this article, four examples of possible lessons on energy levels for high school are described: a particle in a box, a finite square well, the hydrogen atom and a harmonic oscillator. The energy levels are deduced through the use of the steady-state condition and the de Broglie relationship. In particular, the harmonic oscillator energy levels are deduced using correspondence with circular uniform motion.

  11. Quantum Monte Carlo : not just for energy levels.

    SciTech Connect

    Nollett, K. M.; Physics

    2007-01-01

    Quantum Monte Carlo and realistic interactions can provide well-motivated vertices and overlaps for DWBA analyses of reactions. Given an interaction in vaccum, there are several computational approaches to nuclear systems, as you have been hearing: No-core shell model with Lee-Suzuki or Bloch-Horowitz for Hamiltonian Coupled clusters with G-matrix interaction Density functional theory, granted an energy functional derived from the interaction Quantum Monte Carlo - Variational Monte Carlo Green's function Monte Carlo. The last two work directly with a bare interaction and bare operators and describe the wave function without expanding in basis functions, so they have rather different sets of advantages and disadvantages from the others. Variational Monte Carlo (VMC) is built on a sophisticated Ansatz for the wave function, built on shell model like structure modified by operator correlations. Green's function Monte Carlo (GFMC) uses an operator method to project the true ground state out of a reasonable guess wave function.

  12. Energy Levels and the de Broglie Relationship for High School Students

    ERIC Educational Resources Information Center

    Gianino, Concetto

    2008-01-01

    In this article, four examples of possible lessons on energy levels for high school are described: a particle in a box, a finite square well, the hydrogen atom and a harmonic oscillator. The energy levels are deduced through the use of the steady-state condition and the de Broglie relationship. In particular, the harmonic oscillator energy levels…

  13. Energy levels and spectral lines of tungsten, W III through W LXXIV

    NASA Astrophysics Data System (ADS)

    Kramida, A. E.; Shirai, T.

    2009-05-01

    The energy levels and spectral lines of multiply ionized tungsten atoms, W 2+ through W 73+, have been compiled. Experimental data on spectral lines and energy levels exist for the spectra of W III through W VII, W XXVIII through W LI, W LIII, and W LV through LXV. For W VIII, the four lowest energy levels were derived from the series limits of W VII. For W LXIV (Na-like) and W LVI (K-like), we supplement experimental data on energy levels and wavelengths with predicted values found by accurate interpolations and extrapolations along the isoelectronic sequences. For W LXXIII (He-like) and W LXXIV (H-like), theoretical data on energy levels and line wavelengths are compiled. For W III, we include experimentally determined radiative transition probabilities where available. The ground state configurations and terms were determined for all stages of ionization. A value of ionization energy is included for each ion.

  14. Ab-inito calculation of energy level alignment and vacuum level shift at CuPc/C60 interfaces

    NASA Astrophysics Data System (ADS)

    Sai, Na; Zhu, Xiaoyang; Chelikowsky, James; Leung, Kevin

    2012-02-01

    The alignment of the donor and acceptor enegy levels is of crucial importance for organic photovotaic performance. We investigate the interfaical electronic structure and energy level alignment of copper phthalocyanine (CuPc)/fullerene (C60) using ab-inito density functional theory calculations including van der Waals interactions and hybrid density functionals. We show that energy level alignment critically depends on the standing-up and lying-down orientation of the CuPc molecules relative to C60 at the interface. We calculate the magnitude of the interface dipole at different molecular orientations and compare them to the vacuum level shift observed in photoemission spectroscopy. The validity of existing theoretical models which invoke charge transfer on this organic interface will be discussed in light of our predictions. Sandia National Laboratories is a multiprogram laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Deparment of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

  15. Treatment of Electronic Energy Level Transition and Ionization Following the Particle-Based Chemistry Model

    NASA Technical Reports Server (NTRS)

    Liechty, Derek S.; Lewis, Mark

    2010-01-01

    A new method of treating electronic energy level transitions as well as linking ionization to electronic energy levels is proposed following the particle-based chemistry model of Bird. Although the use of electronic energy levels and ionization reactions in DSMC are not new ideas, the current method of selecting what level to transition to, how to reproduce transition rates, and the linking of the electronic energy levels to ionization are, to the author s knowledge, novel concepts. The resulting equilibrium temperatures are shown to remain constant, and the electronic energy level distributions are shown to reproduce the Boltzmann distribution. The electronic energy level transition rates and ionization rates due to electron impacts are shown to reproduce theoretical and measured rates. The rates due to heavy particle impacts, while not as favorable as the electron impact rates, compare favorably to values from the literature. Thus, these new extensions to the particle-based chemistry model of Bird provide an accurate method for predicting electronic energy level transition and ionization rates in gases.

  16. Rotation vibration energy level clustering in the XB1 ground electronic state of PH2

    NASA Astrophysics Data System (ADS)

    Yurchenko, S. N.; Thiel, W.; Jensen, Per; Bunker, P. R.

    2006-10-01

    We use previously determined potential energy surfaces for the Renner-coupled XB1 and AA1 electronic states of the phosphino (PH 2) free radical in a calculation of the energies and wavefunctions of highly excited rotational and vibrational energy levels of the X˜ state. We show how spin-orbit coupling, the Renner effect, rotational excitation, and vibrational excitation affect the clustered energy level patterns that occur. We consider both 4-fold rotational energy level clustering caused by centrifugal distortion, and vibrational energy level pairing caused by local mode behaviour. We also calculate ab initio dipole moment surfaces for the X˜ and A˜ states, and the X˜-A˜ transition moment surface, in order to obtain spectral intensities.

  17. A Simple Approach for the Calculation of Energy Levels of Light Atoms

    ERIC Educational Resources Information Center

    Woodyard, Jack R., Sr.

    1972-01-01

    Describes a method for direct calculation of energy levels by using elementary techniques. Describes the limitations of the approach but also claims that with a minimum amount of labor a student can get greater understanding of atomic physics problems. (PS)

  18. ENERGY LEVELS AND SPECTRAL LINES OF SINGLY IONIZED MANGANESE (Mn II)

    SciTech Connect

    Kramida, Alexander; Sansonetti, Jean E.

    2013-04-01

    This compilation revises the previously recommended list of energy levels of singly ionized manganese (Mn II) and provides a comprehensive list of observed spectral lines and transition probabilities in this spectrum. The new level optimization takes into account critically assessed uncertainties of measured wavelengths and includes about a hundred high-precision wavelengths determined by laser spectroscopy and Fourier transform techniques. Uncertainties of 63% of energy levels and 74% of Ritz wavelengths are reduced by a factor of three on average.

  19. Berry{close_quote}s phase in the presence of a stochastically evolving environment: A geometric mechanism for energy-level broadening

    SciTech Connect

    Gaitan, F.

    1998-09-01

    The generic Berry phase scenario in which a two-level system is coupled to a second system whose dynamical coordinate is slowly varying is generalized to allow for stochastic evolution of the slow system. The stochastic behavior is produced by coupling the slow system to a heat reservoir, which is modeled by a bath of harmonic oscillators initially in equilibrium at temperature T, and whose spectral density has a bandwidth that is small compared to the energy-level spacing of the fast system. The well-known energy-level shifts produced by Berry{close_quote}s phase in the fast system, in conjunction with the stochastic motion of the slow system, leads to a broadening of the fast system energy levels. In the limit of strong damping and sufficiently low temperature, we determine the degree of level broadening analytically, and show that the slow system dynamics satisfies a Langevin equation in which Lorentz-like and electriclike forces appear as a consequence of geometrical effects. We also determine the average energy level shift produced in the fast system by this mechanism. {copyright} {ital 1998} {ital The American Physical Society}

  20. Improved discrimination in photographic density contouring

    NASA Technical Reports Server (NTRS)

    Godding, R. A.

    1974-01-01

    Density discrimination can be accomplished through use of special photographic contouring material which has two sensitive layers (one negative, one positive) on single support. Process will be of interest to investigators who require finer discrimination of densities of original photograph for purposes such as identification of crops and analysis of energy levels of radiating objects.

  1. Effect of temperature-dependent energy-level shifts on a semiconductor's Peltier heat

    SciTech Connect

    Emin, D.

    1984-11-15

    The Peltier heat of a charge carrier in a semiconductor is calculated for the situation in which the electronic energy levels are temperature dependent. The temperature dependences of the electronic energy levels, generally observed optically, arise from their dependences on the vibrational energy of the lattice (e.g., as caused by thermal expansion). It has been suggested that these temperature dependences will typically have a major effect on the Peltier heat. The Peltier heat associated with a given energy level is a thermodynamic quantity; it is the product of the temperature and the change of the entropy of the system when a carrier is added in that level. As such, the energy levels cannot be treated as explicitly temperature dependent. The electron-lattice interaction causing the temperature dependence must be expressly considered. It is found that the carrier's interaction with the atomic vibrations lowers its electronic energy. However, the interaction of the carrier with the atomic vibrations also causes an infinitesimal lowering (approx.1/N) of each of the N vibrational frequencies. As a result, there is a finite carrier-induced increase in the average vibrational energy. Above the Debye temperature, this cancels the lowering of the carrier's electronic energy. Thus, the standard Peltier-heat formula, whose derivation generally ignores the temperature dependence of the electronic energy levels, is regained. This explains the apparent success of the standard formula in numerous analyses of electronic transport experiments.

  2. Revealing energy level structure of individual quantum dots by tunneling rate measured by single-electron sensitive electrostatic force spectroscopy.

    PubMed

    Roy-Gobeil, Antoine; Miyahara, Yoichi; Grutter, Peter

    2015-04-01

    We present theoretical and experimental studies of the effect of the density of states of a quantum dot (QD) on the rate of single-electron tunneling that can be directly measured by electrostatic force microscopy (e-EFM) experiments. In e-EFM, the motion of a biased atomic force microscope cantilever tip modulates the charge state of a QD in the Coulomb blockade regime. The charge dynamics of the dot, which is detected through its back-action on the capacitavely coupled cantilever, depends on the tunneling rate of the QD to a back-electrode. The density of states of the QD can therefore be measured through its effect on the energy dependence of tunneling rate. We present experimental data on individual 5 nm colloidal gold nanoparticles that exhibit a near continuous density of state at 77 K. In contrast, our analysis of already published data on self-assembled InAs QDs at 4 K clearly reveals discrete degenerate energy levels. PMID:25761141

  3. Optical Energy Levels Scheme for Co2+ doped in K(Mg,Zn)F3 Fluoroperovskites

    NASA Astrophysics Data System (ADS)

    Barb, A. M.; Gruia, A. S.; Avram, C. N.

    2016-02-01

    The aim of this paper is to model the crystal field parameters and simulate the fine structure of optical energy levels scheme of Co2+:K(Mg,Zn)F3 systems. The crystal field parameters were modeled in the frame of an Exchange Charge Model of the crystal field theory, taking into account the effects of the covalent bond formation between the Co2+ and F- ions. The obtained parameters were used for simulating the fine structure of the system energy levels scheme, by diagonalization of the full Hamiltonian matrix, in the base of 100 wave functions of Co2+ ion. For resolving some discrepancies, the electron-phonon interaction in 4T2g excited state is investigated in the frame of the Ham theory, with the Jahn-Teller stabilization energy calculation. The comparison of the calculated energy levels with experimental data gives a good agreement, which confirms the model and used method.

  4. Correspondence between energy levels and evolution curves of fixed points in nonlinear Landau-Zener model

    NASA Astrophysics Data System (ADS)

    Liu, Xuan-Zuo; Tian, Dong-Ping; Chong, Bo

    2016-06-01

    Liu et al. [Phys. Rev. Lett. 90(17), 170404 (2003)] proved that the characters of transition probabilities in the adiabatic limit should be entirely determined by the topology of energy levels and the stability of fixed points in the classical Hamiltonian system, according to the adiabatic theorem. In the special case of nonlinear Landau-Zener model, we simplify their results to be that the properties of transition probabilities in the adiabatic limit should just be determined by the attributes of fixed points. It is because the topology of energy levels is governed by the behavior and symmetries of fixed points, and intuitively this fact is represented as a correspondence between energy levels and evolution curves of the fixed points which can be quantitatively described as the same complexity numbers.

  5. Chemical control over the energy-level alignment in a two-terminal junction

    NASA Astrophysics Data System (ADS)

    Yuan, Li; Franco, Carlos; Crivillers, Núria; Mas-Torrent, Marta; Cao, Liang; Sangeeth, C. S. Suchand; Rovira, Concepció; Veciana, Jaume; Nijhuis, Christian A.

    2016-07-01

    The energy-level alignment of molecular transistors can be controlled by external gating to move molecular orbitals with respect to the Fermi levels of the source and drain electrodes. Two-terminal molecular tunnelling junctions, however, lack a gate electrode and suffer from Fermi-level pinning, making it difficult to control the energy-level alignment of the system. Here we report an enhancement of 2 orders of magnitude of the tunnelling current in a two-terminal junction via chemical molecular orbital control, changing chemically the molecular component between a stable radical and its non-radical form without altering the supramolecular structure of the junction. Our findings demonstrate that the energy-level alignment in self-assembled monolayer-based junctions can be regulated by purely chemical modifications, which seems an attractive alternative to control the electrical properties of two-terminal junctions.

  6. Impact behaviour of Napier/polyester composites under different energy levels

    NASA Astrophysics Data System (ADS)

    Fahmi, I.; Majid, M. S. Abdul; Afendi, M.; Haslan, M.; Helmi E., A.; M. Haameem J., A.

    2016-07-01

    The effects of different energy levels on the impact behaviour of Napier fibre/polyester reinforced composites were investigated. Napier fibre was extracted using traditional water retting process to be utilized as reinforcing materials in polyester composite laminates. 25% fibre loading composite laminates were prepared and impacted at three different energy levels; 2.5,5 and 7.5 J using an instrumented drop weight impact testing machine (IMATEK IM10). The outcomes show that peak force and contact time increase with increased impact load. The energy absorption was then calculated from the force displacement curve. The results indicated that the energy absorption decreases with increasing energy levels of the impact. Impacted specimens were observed visually for fragmentation fracture using an optical camera to identify the failure mechanisms. Fracture fragmentation pattern from permanent dent to perforation with radial and circumferential was observed.

  7. Chemical control over the energy-level alignment in a two-terminal junction

    PubMed Central

    Yuan, Li; Franco, Carlos; Crivillers, Núria; Mas-Torrent, Marta; Cao, Liang; Sangeeth, C. S. Suchand; Rovira, Concepció; Veciana, Jaume; Nijhuis, Christian A.

    2016-01-01

    The energy-level alignment of molecular transistors can be controlled by external gating to move molecular orbitals with respect to the Fermi levels of the source and drain electrodes. Two-terminal molecular tunnelling junctions, however, lack a gate electrode and suffer from Fermi-level pinning, making it difficult to control the energy-level alignment of the system. Here we report an enhancement of 2 orders of magnitude of the tunnelling current in a two-terminal junction via chemical molecular orbital control, changing chemically the molecular component between a stable radical and its non-radical form without altering the supramolecular structure of the junction. Our findings demonstrate that the energy-level alignment in self-assembled monolayer-based junctions can be regulated by purely chemical modifications, which seems an attractive alternative to control the electrical properties of two-terminal junctions. PMID:27456200

  8. Chemical control over the energy-level alignment in a two-terminal junction.

    PubMed

    Yuan, Li; Franco, Carlos; Crivillers, Núria; Mas-Torrent, Marta; Cao, Liang; Sangeeth, C S Suchand; Rovira, Concepció; Veciana, Jaume; Nijhuis, Christian A

    2016-01-01

    The energy-level alignment of molecular transistors can be controlled by external gating to move molecular orbitals with respect to the Fermi levels of the source and drain electrodes. Two-terminal molecular tunnelling junctions, however, lack a gate electrode and suffer from Fermi-level pinning, making it difficult to control the energy-level alignment of the system. Here we report an enhancement of 2 orders of magnitude of the tunnelling current in a two-terminal junction via chemical molecular orbital control, changing chemically the molecular component between a stable radical and its non-radical form without altering the supramolecular structure of the junction. Our findings demonstrate that the energy-level alignment in self-assembled monolayer-based junctions can be regulated by purely chemical modifications, which seems an attractive alternative to control the electrical properties of two-terminal junctions. PMID:27456200

  9. Experimental Energy Levels and Partition Function of the 12C2 Molecule

    NASA Astrophysics Data System (ADS)

    Furtenbacher, Tibor; Szabó, István; Császár, Attila G.; Bernath, Peter F.; Yurchenko, Sergei N.; Tennyson, Jonathan

    2016-06-01

    The carbon dimer, the 12C2 molecule, is ubiquitous in astronomical environments. Experimental-quality rovibronic energy levels are reported for 12C2, based on rovibronic transitions measured for and among its singlet, triplet, and quintet electronic states, reported in 42 publications. The determination utilizes the Measured Active Rotational-Vibrational Energy Levels (MARVEL) technique. The 23,343 transitions measured experimentally and validated within this study determine 5699 rovibronic energy levels, 1325, 4309, and 65 levels for the singlet, triplet, and quintet states investigated, respectively. The MARVEL analysis provides rovibronic energies for six singlet, six triplet, and two quintet electronic states. For example, the lowest measurable energy level of the {{a}}{}3{{{\\Pi }}}{{u}} state, corresponding to the J = 2 total angular momentum quantum number and the F 1 spin-multiplet component, is 603.817(5) cm‑1. This well-determined energy difference should facilitate observations of singlet–triplet intercombination lines, which are thought to occur in the interstellar medium and comets. The large number of highly accurate and clearly labeled transitions that can be derived by combining MARVEL energy levels with computed temperature-dependent intensities should help a number of astrophysical observations as well as corresponding laboratory measurements. The experimental rovibronic energy levels, augmented, where needed, with ab initio variational ones based on empirically adjusted and spin–orbit coupled potential energy curves obtained using the Duo code, are used to obtain a highly accurate partition function, and related thermodynamic data, for 12C2 up to 4000 K.

  10. WAVELENGTHS, ENERGY LEVELS, LIFETIMES, AND WEIGHTED OSCILLATOR STRENGTHS FOR THE S VIII SPECTRUM

    SciTech Connect

    Pagan, C. J. B.; Cavalcanti, G. H.; Trigueiros, A. G.; Jupen, C.

    2011-10-01

    The weighted oscillator strengths (gf) and lifetimes for S VIII presented in this work were obtained by a multiconfigurational Hartree-Fock relativistic approach. In this calculation, the electrostatic energy parameters were optimized by a least-squares procedure in order to improve the adjustment to experimental energy levels. The values for gf and lifetimes were then calculated on the basis of these adjusted parameters. New classifications are proposed for energy levels belonging to the 4s and 4d configurations and lines related to them.

  11. Energy levels of odd-even nuclei using broken pair model

    SciTech Connect

    Hamammu, I. M.; Haq, S.; Eldahomi, J. M.

    2012-09-06

    A method to calculate energy levels and wave functions of odd-even nuclei, in the frame work of the broken pair model have been developed. The accuracy of the model has been tested by comparing the shell model results of limiting cases in which the broken pair model exactly coincides with the shell model, where there are two-proton/neutron + one-neutron/proton in the valence levels. The model is then applied to calculate the energy levels of some nuclei in the Zirconium region. The model results compare reasonably well with the shell model as well as with the experimental data.

  12. Calculating splittings between energy levels of different symmetry using path-integral methods.

    PubMed

    Mátyus, Edit; Althorpe, Stuart C

    2016-03-21

    It is well known that path-integral methods can be used to calculate the energy splitting between the ground and the first excited state. Here we show that this approach can be generalized to give the splitting patterns between all the lowest energy levels from different symmetry blocks that lie below the first-excited totally symmetric state. We demonstrate this property numerically for some two-dimensional models. The approach is likely to be useful for computing rovibrational energy levels and tunnelling splittings in floppy molecules and gas-phase clusters. PMID:27004864

  13. Energy Levels and Half-Lives of Gallium Isotopes Obtained by Photo-Nuclear Reaction

    NASA Astrophysics Data System (ADS)

    Dulger, F.; Akkoyun, S.; Bayram, T.; Dapo, H.; Boztosun, I.

    2015-04-01

    We have run an experiment to determine the energy levels and half-lives of Gallium nucleus by using the photonuclear reactions with end-point energy of 18 MeV bremsstrahlung photons, produced by a clinical linear accelerator. As a result of 71Ga(y,n)70Ga and 69Ga(Y,n)68Ga photonuclear reactions, the energy levels and half-lives of 70Ga and 68Ga nuclei have been determined. The results are in good agreement with the literature values.

  14. Energy levels of odd-even nuclei using broken pair model

    NASA Astrophysics Data System (ADS)

    Hamammu, I. M.; Haq, S.; Eldahomi, J. M.

    2012-09-01

    A method to calculate energy levels and wave functions of odd-even nuclei, in the frame work of the broken pair model have been developed. The accuracy of the model has been tested by comparing the shell model results of limiting cases in which the broken pair model exactly coincides with the shell model, where there are two-proton/neutron + one-neutron/proton in the valence levels. The model is then applied to calculate the energy levels of some nuclei in the Zirconium region. The model results compare reasonably well with the shell model as well as with the experimental data.

  15. Energy Levels in Helium and Neon Atoms by an Electron-Impact Method.

    ERIC Educational Resources Information Center

    Taylor, N.; And Others

    1981-01-01

    Electronic energy levels in noble gas atoms may be determined with a simple teaching apparatus incorporating a resonance potentials tube in which the electron beam intensity is held constant. The resulting spectra are little inferior to those obtained by more elaborate electron-impact methods and complement optical emission spectra. (Author/SK)

  16. Improved Experimental and Theoretical Energy Levels of Carbon I from Solar Infrared Spectra

    NASA Technical Reports Server (NTRS)

    Chang, Edward S.; Geller, Murray

    1997-01-01

    We have improved the energy levels in neutral carbon using high resolution infrared solar spectra. The main source is the ATMOS spectrum measured by the Fourier transaform spectroscopy technique from 600 to 4800 cm-1, supplemented by the MARK IV balloon data, covering from 4700 to 5700 cm-1.

  17. Peculiarities of collisional excitation transfer with excited screened energy levels of atoms

    SciTech Connect

    Gerasimov, V. A.; Gerasimov, V. V.; Pavlinskiy, A. V.

    2007-09-15

    We report an experimental discovery of deviations from the known regularities in collisional excitation transfer processes for metal atoms. The collisional excitation transfer with excited screened energy levels of thulium and dysprosium atoms is studied. The selecting role of the screening 6s shell in collisional excitation transfer is shown.

  18. Theoretical Study of Energy Levels and Transition Probabilities of Boron Atom

    NASA Astrophysics Data System (ADS)

    Tian Yi, Zhang; Neng Wu, Zheng

    2009-08-01

    Full Text PDF Though the electrons configuration for boron atom is simple and boron atom has long been of interest for many researchers, the theoretical studies for properties of BI are not systematic, there are only few results reported on energy levels of high excited states of boron, and transition measurements are generally restricted to transitions involving ground states and low excited states without considering fine structure effects, provided only multiplet results, values for transitions between high excited states are seldom performed. In this article, by using the scheme of the weakest bound electron potential model theory calculations for energy levels of five series are performed and with the same method we give the transition probabilities between excited states with considering fine structure effects. The comprehensive set of calculations attempted in this paper could be of some value to workers in the field because of the lack of published calculations for the BI systems. The perturbations coming from foreign perturbers are taken into account in studying the energy levels. Good agreement between our results and the accepted values taken from NIST has been obtained. We also reported some values of energy levels and transition probabilities not existing on the NIST data bases.

  19. Probing Energy Levels of Large Array Quantum Dot Superlattice by Electronic Transport Measurement

    NASA Astrophysics Data System (ADS)

    Bisri, S. Z.; Degoli, E.; Spallanzani, N.; Krishnan, G.; Kooi, B.; Ghica, C.; Yarema, M.; Protesescu, L.; Heiss, W.; Kovalenko, M.; Pulci, O.; Ossicini, S.; Iwasa, Y.; Loi, M. A.

    2015-03-01

    Colloidal quantum dot superlattice (CQDS) emerges as new type of hybrid solids allowing easy fabrication of devices that exploits the quantum confinement properties of individual QD. This materials displays peculiar characters, making investigation of their transport properties nontrivial. Besides the bandgap variations, 0D nature of QD lead to the formation of discrete energy subbands. These subbands are crucial for multiple exciton generation (for efficient solar cell), thermoelectric material and multistate transistor. Full understanding of the CQDS energy level structure is vital to use them in complex devices. Here we show a powerful method to determine the CQDS electronic energy levels from their intrinsic charge transport characteristics. Via the use of ambipolar transistors with CQDS as active materials and gated using highly capacitive ionic liquid gating, Fermi energy can be largely tuned. It can access energy levels beyond QD's HOMO & LUMO. Ability to probe not only the bandgap, but also the discrete energy level from large assembly of QD at room temperature suggests the formation of energy minibands in this system.

  20. A detailed analysis of the energy levels configuration existing in the band gap of supersaturated silicon with titanium for photovoltaic applications

    NASA Astrophysics Data System (ADS)

    Pérez, E.; Dueñas, S.; Castán, H.; García, H.; Bailón, L.; Montero, D.; García-Hernansanz, R.; García-Hemme, E.; Olea, J.; González-Díaz, G.

    2015-12-01

    The energy levels created in supersaturated n-type silicon substrates with titanium implantation in the attempt to create an intermediate band in their band-gap are studied in detail. Two titanium ion implantation doses (1013 cm-2 and 1014 cm-2) are studied in this work by conductance transient technique and admittance spectroscopy. Conductance transients have been measured at temperatures of around 100 K. The particular shape of these transients is due to the formation of energy barriers in the conduction band, as a consequence of the band-gap narrowing induced by the high titanium concentration. Moreover, stationary admittance spectroscopy results suggest the existence of different energy level configuration, depending on the local titanium concentration. A continuum energy level band is formed when titanium concentration is over the Mott limit. On the other hand, when titanium concentration is lower than the Mott limit, but much higher than the donor impurity density, a quasi-continuum energy level distribution appears. Finally, a single deep center appears for low titanium concentration. At the n-type substrate, the experimental results obtained by means of thermal admittance spectroscopy at high reverse bias reveal the presence of single levels located at around Ec-425 and Ec-275 meV for implantation doses of 1013 cm-2 and 1014 cm-2, respectively. At low reverse bias voltage, quasi-continuously distributed energy levels between the minimum of the conduction bands, Ec and Ec-450 meV, are obtained for both doses. Conductance transients detected at low temperatures reveal that the high impurity concentration induces a band gap narrowing which leads to the formation of a barrier in the conduction band. Besides, the relationship between the activation energy and the capture cross section values of all the energy levels fits very well to the Meyer-Neldel rule. As it is known, the Meyer-Neldel rule typically appears in processes involving multiple excitations, like

  1. A detailed analysis of the energy levels configuration existing in the band gap of supersaturated silicon with titanium for photovoltaic applications

    SciTech Connect

    Pérez, E.; Dueñas, S.; Castán, H.; García, H.; Bailón, L.; Montero, D.; García-Hernansanz, R.; García-Hemme, E.; González-Díaz, G.; Olea, J.

    2015-12-28

    The energy levels created in supersaturated n-type silicon substrates with titanium implantation in the attempt to create an intermediate band in their band-gap are studied in detail. Two titanium ion implantation doses (10{sup 13 }cm{sup -2} and 10{sup 14 }cm{sup -2}) are studied in this work by conductance transient technique and admittance spectroscopy. Conductance transients have been measured at temperatures of around 100 K. The particular shape of these transients is due to the formation of energy barriers in the conduction band, as a consequence of the band-gap narrowing induced by the high titanium concentration. Moreover, stationary admittance spectroscopy results suggest the existence of different energy level configuration, depending on the local titanium concentration. A continuum energy level band is formed when titanium concentration is over the Mott limit. On the other hand, when titanium concentration is lower than the Mott limit, but much higher than the donor impurity density, a quasi-continuum energy level distribution appears. Finally, a single deep center appears for low titanium concentration. At the n-type substrate, the experimental results obtained by means of thermal admittance spectroscopy at high reverse bias reveal the presence of single levels located at around E{sub c}-425 and E{sub c}-275 meV for implantation doses of 10{sup 13 }cm{sup −2} and 10{sup 14 }cm{sup −2}, respectively. At low reverse bias voltage, quasi-continuously distributed energy levels between the minimum of the conduction bands, E{sub c} and E{sub c}-450 meV, are obtained for both doses. Conductance transients detected at low temperatures reveal that the high impurity concentration induces a band gap narrowing which leads to the formation of a barrier in the conduction band. Besides, the relationship between the activation energy and the capture cross section values of all the energy levels fits very well to the Meyer-Neldel rule. As it is known

  2. A system for measuring thermal activation energy levels in silicon by thermally stimulated capacitance

    NASA Technical Reports Server (NTRS)

    Cockrum, R. H.

    1982-01-01

    One method being used to determine energy level(s) and electrical activity of impurities in silicon is described. The method is called capacitance transient spectroscopy (CTS). It can be classified into three basic categories: the thermally stimulated capacitance method, the voltage-stimulated capacitance method, and the light-stimulated capacitance method; the first two categories are discussed. From the total change in capacitance and the time constant of the capacitance response, emission rates, energy levels, and trap concentrations can be determined. A major advantage of using CTS is its ability to detect the presence of electrically active impurities that are invisible to other techniques, such as Zeeman effect atomic absorption, and the ability to detect more than one electrically active impurity in a sample. Examples of detection of majority and minority carrier traps from gold donor and acceptor centers in silicon using the capacitance transient spectrometer are given to illustrate the method and its sensitivity.

  3. Variational Calculations of Ro-Vibrational Energy Levels and Transition Intensities for Tetratomic Molecules

    NASA Technical Reports Server (NTRS)

    Schwenke, David W.; Langhoff, Stephen R. (Technical Monitor)

    1995-01-01

    A description is given of an algorithm for computing ro-vibrational energy levels for tetratomic molecules. The expressions required for evaluating transition intensities are also given. The variational principle is used to determine the energy levels and the kinetic energy operator is simple and evaluated exactly. The computational procedure is split up into the determination of one dimensional radial basis functions, the computation of a contracted rotational-bending basis, followed by a final variational step coupling all degrees of freedom. An angular basis is proposed whereby the rotational-bending contraction takes place in three steps. Angular matrix elements of the potential are evaluated by expansion in terms of a suitable basis and the angular integrals are given in a factorized form which simplifies their evaluation. The basis functions in the final variational step have the full permutation symmetries of the identical particles. Sample results are given for HCCH and BH3.

  4. Two-wavelength holographic recording in photopolymer using four-energy-level system: experiments and modeling

    NASA Astrophysics Data System (ADS)

    Lin, Chun-Hua; Cho, Sheng-Lung; Lin, Shiuan-Huei; Chi, Sien; Hsu, Ken-Yuh

    2014-11-01

    We investigate a two-wavelength method for recording a persistent hologram in a doped photopolymer. The recording method is based on two separated optical excitations of the four-energy-level system of the doped element, one at λ=325 nm as the sensitizing wavelength and the other at λ=647 nm as the writing wavelength, allowing for an experimental demonstration of nondestructive readout in phenanthrenequinone-doped poly(methyl methacrylate). Further, a four-energy-level rate equations model is proposed for describing the dynamics of hologram recording. The model successfully explains our experimental finding and further provides a general method to investigate such a two-wavelength holographic recording in photopolymer.

  5. Critically Evaluated Energy Levels and Spectral Lines of Singly Ionized Indium (In II)

    PubMed Central

    Kramida, A

    2013-01-01

    A comprehensive list of the best measured wavelengths in the In II spectrum has been compiled. Uncertainties of the wavelength measurements have been analyzed, and existing inconsistencies have been resolved. An optimized set of fine-structure energy levels that fits all observed wavelengths has been derived. Uncertainties of the energy level values have been reduced by an order of magnitude. An improved value of the ionization limit of In II has been determined by fitting quantum-defect and polarization formulas for several series of levels. Intensities of lines observed by different authors have been analyzed and converted to a uniform scale. A set of recommended values of radiative transition rates has been critically compiled, and uncertainties of these rates have been estimated. The hyperfine structure interval in the 5s 2S ground state of In III has been determined from the measurements of the 5sng and 5snh series in In II. PMID:26401424

  6. Hybrid variational-perturbation method for calculating ro-vibrational energy levels of polyatomic molecules

    NASA Astrophysics Data System (ADS)

    Pavlyuchko, A. I.; Yurchenko, S. N.; Tennyson, Jonathan

    2015-07-01

    A procedure for calculation of rotational-vibrational states of medium-sized molecules is presented. It combines the advantages of variational calculations and perturbation theory. The vibrational problem is solved by diagonalising a Hamiltonian matrix, which is partitioned into two sub-blocks. The first, smaller sub-block includes matrix elements with the largest contribution to the energy levels targeted in the calculations. The second, larger sub-block comprises those basis states which have little effect on these energy levels. Numerical perturbation theory, implemented as a Jacobi rotation, is used to compute the contributions from the matrix elements of the second sub-block. Only the first sub-block needs to be stored in memory and diagonalised. Calculations of the vibrational-rotational energy levels also employ a partitioning of the Hamiltonian matrix into sub-blocks, each of which corresponds either to a single vibrational state or a set of resonating vibrational states, with all associated rotational levels. Physically, this partitioning is efficient when the Coriolis coupling between different vibrational states is small. Numerical perturbation theory is used to include the cross-contributions from different vibrational states. Separate individual sub-blocks are then diagonalised, replacing the diagonalisation of a large Hamiltonian matrix with a number of small matrix diagonalisations. Numerical examples show that the proposed hybrid variational-perturbation method greatly speeds up the variational procedure without significant loss of precision for both vibrational-rotational energy levels and transition intensities. The hybrid scheme can be used for accurate nuclear motion calculations on molecules with up to 15 atoms on currently available computers.

  7. Interfacial energy level bending in a crystalline p/p-type organic heterostructure

    SciTech Connect

    Zhu Feng; Grobosch, Mandy; Treske, Uwe; Knupfer, Martin; Huang Lizhen; Ji Shiliang; Yan Donghang

    2011-05-16

    A conduction channel was observed at the heterointerface of the crystalline p-type organic films copper phthalocyanine (CuPc) and 2,5-bis(4-biphenylyl) bithiophene (BP2T). Energy level bending at the interface is confirmed by photoemission spectroscopy, which verifies a charge transfer between CuPc and BP2T. This provides a further route to utilize interfacial electronic properties in functional devices and also documents the importance of reconsidering the interfacial electronic structure of organic heterostructures.

  8. Effect of a metallic gate on the energy levels of a shallow donor

    SciTech Connect

    Slachmuylders, A. F.; Partoens, B.; Peeters, F. M.; Magnus, W.

    2008-02-25

    We have investigated the effect of a metallic gate on the bound states of a shallow donor located near the gate. We calculate the energy spectrum as a function of the distance between the metallic gate and the donor and find an anticrossing behavior in the energy levels for certain distances. We show how a transverse electric field can tune the average position of the electron with respect to the metallic gate and the impurity.

  9. Model for describing non-equilibrium helium plasma energy level population

    NASA Astrophysics Data System (ADS)

    Kavyrshin, D. I.; Chinnov, V. F.; Ageev, A. G.

    2015-11-01

    A new method for calculating the population of excited levels of helium atoms and ions is suggested. The method is based on direct solution of a system of balance equations for all energy levels for which it was possible to obtain process speed constants. The equations include terms for the processes of particle loss and income by excitation and deexcitation, ionization and recombination as well as losses due to diffusion and radiation. The challenge of solution of such large system is also discussed.

  10. Perovskite Solar Cells Employing Dopant-Free Organic Hole Transport Materials with Tunable Energy Levels.

    PubMed

    Liu, Yongsheng; Hong, Ziruo; Chen, Qi; Chen, Huajun; Chang, Wei-Hsuan; Yang, Yang Michael; Song, Tze-Bin; Yang, Yang

    2016-01-20

    Conjugated small-molecule hole-transport materials (HTMs) with tunable energy levels are designed and synthesized for efficient perovskite solar cells. A champion device with efficiency of 16.2% is demonstrated using a dopant-free DERDTS-TBDT HTM, while the DORDTS-DFBT-HTM-based device shows an inferior performance of 6.2% due to its low hole mobility and unmatched HOMO level with the valence band of perovskite film. PMID:26588665

  11. Resonance lines and energy levels of Cs III, Ba IV, and La V

    NASA Technical Reports Server (NTRS)

    Epstein, G. L.; Reader, J.

    1976-01-01

    Spectra of Cs III, Ba IV, and La V were photographed in a low-voltage sliding spark on a 10.7 m normal-incidence vacuum spectrograph. These ions are isoelectronic with neutral iodine and display a halogen-like energy level structure. Detailed isoelectronic comparisons, level transition diagrams, and tabular data on the transitions of the ions and percentage compositions of Cs III configurations are presented.

  12. Calculations of energy levels and lifetimes of low-lying states of barium and radium

    SciTech Connect

    Dzuba, V. A.; Ginges, J. S. M.

    2006-03-15

    We use the configuration-interaction method and many-body perturbation theory to perform accurate calculations of energy levels, transition amplitudes, and lifetimes of low-lying states of barium and radium. Calculations for radium are needed for the planning of measurements of parity- and time-invariance-violating effects which are strongly enhanced in this atom. Calculations for barium are used to control the accuracy of the calculations.

  13. Enhanced cardiovascular function and energy level by a novel chromium (III)-supplement.

    PubMed

    Thirunavukkarasu, Mahesh; Penumathsa, Sureshvarma; Juhasz, Bela; Zhan, Lijun; Bagchi, Manashi; Yasmin, Taharat; Shara, Michael A; Thatte, Hemant S; Bagchi, Debasis; Maulik, Nilanjana

    2006-01-01

    The impetus for the novel Energy Formula (EF) which combines the niacin-bound chromium (III) (0.45%) (NBC), standardized extract of Withania somnifera extracts (10.71%), caffeine (22.76%), D-ribose (10.71%) and selected amino acids such as phenylalanine, taurine and glutamine (55.37%) was based on the knowledge of the cardioprotective potentials of the Withania somnifera extract, caffeine and D-ribose as well as their abilities to increase energy levels and the abilities of amino acids to increase the muscle mass and energy levels. The effect of oral supplementation of EF on the safety, myocardial energy levels and cardioprotective ability were investigated in an ischemic-reperfused myocardium model in both male and female Sprague-Dawley rats over 90 days trial period. At the completion of 90 days, the EF-treated male and female rats gained 9.4% and 3.1% less body weights, respectively, as compared to their corresponding control groups. No significant difference was found in the levels of lipid peroxidation and activities of hepatic Aspartate transaminase, Alanine transaminase and Alkaline phosphatase in EF treatment when compared with control animals. The male and female rat hearts were subjected to 30 min of global ischemia followed by 2 h of reperfusion at 30 and 90 days of EF treatment. Cardiovascular functions including heart rate, coronary flow, aortic flow, dp/dt(max), left ventricular developed pressure (LVDP) and infarct size were monitored. The levels of myocardial adenosine triphosphate (ATP), creatine phosphate (CP), phospho-adenosine monophosphate kinase (p-AMPK) levels, were analyzed at the end of 30 and 90 days of treatment. Significant improvement was observed in all parameters in the EF treatment groups as compared to their corresponding controls. Thus the niacin-bound chromium (III) based energy formula is safe and effective supplement to boost energy levels and cardioprotection. PMID:17012764

  14. Energy levels in helium and neon atoms by an electron-impact method

    NASA Astrophysics Data System (ADS)

    Taylor, N.; Bartle, K. D.; Mills, D.; Beard, D. S.

    1981-03-01

    Electronic energy levels in noble gas atoms may be determined with a simple teaching apparatus incorporating a resonance potentials tube in which the electron beam intensity is held constant. The resulting spectra are little inferior to those obtained by more elaborate electron-impact methods and complement optical emission spectra. Singlet-triplet energy differences may be resolved, and the spectra of helium and neon may be used to illustrate the applicability of Russell-Saunders and other, ''intermediate,'' coupling schemes.

  15. Crystal field parameters and energy levels scheme of trivalent chromium doped BSO

    SciTech Connect

    Petkova, P.; Andreici, E.-L.; Avram, N. M.

    2014-11-24

    The aim of this paper is to give an analysis of crystal field parameters and energy levels schemes for the above doped material, in order to give a reliable explanation for experimental data. The crystal field parameters have been modeled in the frame of Exchange Charge Model (ECM) of the crystal field theory, taken into account the geometry of systems, with actually site symmetry of the impurity ions. The effect of the charges of the ligands and covalence bonding between chromium cation and oxygen anions, in the cluster approach, also were taken into account. With the obtained values of the crystal field parameters we simulated the scheme of energy levels of chromium ions by diagonalizing the matrix of the Hamiltonian of the doped crystal. The obtained energy levels and estimated Racah parameters B and C were compared with the experimental spectroscopic data and discussed. Comparison with experiment shows that the results are quite satisfactory which justify the model and simulation scheme used for the title system.

  16. Energy-level structure of the hydrogen atom confined by a penetrable cylindrical cavity

    NASA Astrophysics Data System (ADS)

    Cabrera-Trujillo, R.; Méndez-Fragoso, R.; Cruz, S. A.

    2016-01-01

    The bound-state energy spectrum and its evolution for a hydrogen atom located along the axis of a standard cylindrical confining cavity with either impenetrable or penetrable confining boundaries are obtained by solving the stationary Schrödinger equation using a finite differences approach. New results are first presented for a nuclear-centered position for the penetrable case as the barrier height and cavity size change. Special attention is then given to the energy-level dependence on the nuclear position along the cylinder axis, where proper identification for the evolution of states from the nuclear-centered position (centered states) up to the cylinder cap (cap states) is proposed, while the corresponding state evolution for intermediate nuclear positions (intermediate states) remains consistent with node conservation and symmetry. It is found that in general the energy levels evolve with an increasing value as the nuclear position is shifted from the central position up to a cylinder cap. As the barrier height (and cavity size) are reduced, a progressive extinction of bound states appears in the order cap states, intermediate states and centered states. Finally, a predominance of cavity-size over barrier-height effects on the energy level shift is found.

  17. Effect of acidity on the energy level of curcumin dye extracted from Curcuma longa L.

    NASA Astrophysics Data System (ADS)

    Agustia, Yuda Virgantara; Suyitno, Arifin, Zainal; Sutanto, Bayu

    2016-03-01

    The purpose of this research is to investigate the effect of acidity on the energy level of curcumin dye. The natural dye, curcumin, was synthesized from Curcuma longa L. using a simple extraction technique. The purification of curcumin dye was conducted in a column of chromatography and its characteristics were studied. Next, the purified curcumin dye was added by benzoic acids until various acidities of 3.0, 3.5, 4.0, 4.5, and 5.0. The absorbance spectra and the functionality groups found in the dyes were detected by ultraviolet-visible spectroscopy and Fourier-transform infrared spectroscopy, respectively. Meanwhile, the energy level of the dyes, EHOMO and ELUMO was measured by cyclic voltammetry. The best energy level of curcumin dye was achieved at pH 3.5 where Ered = -0.37V, ELUMO = -4.28 eV, Eox = 1.15V, EHOMO = -5.83 eV, and Eband gap = 1.55 eV. Therefore, the purified curcumin dye added by benzoic acid was promising for sensitizing the dye-sensitized solar cells.

  18. by ligand exchange: utilizing energy level alignment for efficiently reducing carrier rec ombination

    NASA Astrophysics Data System (ADS)

    Wang, Xia; Kou, Dong-Xing; Zhou, Wen-Hui; Zhou, Zheng-Ji; Wu, Si-Xin; Cao, Xuan

    2014-05-01

    In this work, we employed a convenient one-step synthesis method for synthesizing Cu2ZnSnSe4 (CZTSe) nanocrystals (NCs) in an excess selenium environment. This excess selenium situation enhanced the reaction of metal acetylacetonates with selenium, resulting in the burst nucleation of NCs at relatively low temperatures. The phase morphology and surface and optoelectronic properties of NCs before and after ligand exchange were discussed in depth. It was found that pure tetragonal-phase structure CZTSe NCs with approximately 1.7-eV bandgap could be synthesized. The removal of large organic molecules on CZTSe NCs after ligand exchange by S2- decreased the resistivity. The bandgap of the films after ligand exchange by 550°C selenization was also decreased due to better crystallinity. For potential application in CZTSe solar cells, we constructed an energy level diagram to explain the mutual effect between the absorption layer and CdS layer. Using cyclic voltammetry (CV) measurement, we found that the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy levels of CZTSe films shifted down after ligand exchange. After energy level alignment at the CdS/CZTSe interface, a type I band alignment structure was more conveniently formed after ligand exchange. This structure acted as the barrier against injection electrons from ZnO to the CZTSe layer, and recombination would subsequently be depressed.

  19. Pronounced polarization-induced energy level shifts at boundaries of organic semiconductor nanostructures.

    PubMed

    Cochrane, K A; Schiffrin, A; Roussy, T S; Capsoni, M; Burke, S A

    2015-01-01

    Organic semiconductor devices rely on the movement of charge at and near interfaces, making an understanding of energy level alignment at these boundaries an essential element of optimizing materials for electronic and optoelectronic applications. Here we employ low temperature scanning tunneling microscopy and spectroscopy to investigate a model system: two-dimensional nanostructures of the prototypical organic semiconductor, PTCDA (3,4,9,10-perylenetetracarboxylic dianhydride) adsorbed on NaCl (2 ML)/Ag(111). Pixel-by-pixel scanning tunneling spectroscopy allows mapping of occupied and unoccupied electronic states across these nanoislands with sub-molecular spatial resolution, revealing strong electronic differences between molecules at the edges and those in the centre, with energy level shifts of up to 400 meV. We attribute this to the change in electrostatic environment at the boundaries of clusters, namely via polarization of neighbouring molecules. The observation of these strong shifts illustrates a crucial issue: interfacial energy level alignment can differ substantially from the bulk electronic structure in organic materials. PMID:26440933

  20. Pronounced polarization-induced energy level shifts at boundaries of organic semiconductor nanostructures

    NASA Astrophysics Data System (ADS)

    Cochrane, K. A.; Schiffrin, A.; Roussy, T. S.; Capsoni, M.; Burke, S. A.

    2015-10-01

    Organic semiconductor devices rely on the movement of charge at and near interfaces, making an understanding of energy level alignment at these boundaries an essential element of optimizing materials for electronic and optoelectronic applications. Here we employ low temperature scanning tunneling microscopy and spectroscopy to investigate a model system: two-dimensional nanostructures of the prototypical organic semiconductor, PTCDA (3,4,9,10-perylenetetracarboxylic dianhydride) adsorbed on NaCl (2 ML)/Ag(111). Pixel-by-pixel scanning tunneling spectroscopy allows mapping of occupied and unoccupied electronic states across these nanoislands with sub-molecular spatial resolution, revealing strong electronic differences between molecules at the edges and those in the centre, with energy level shifts of up to 400 meV. We attribute this to the change in electrostatic environment at the boundaries of clusters, namely via polarization of neighbouring molecules. The observation of these strong shifts illustrates a crucial issue: interfacial energy level alignment can differ substantially from the bulk electronic structure in organic materials.

  1. Pronounced polarization-induced energy level shifts at boundaries of organic semiconductor nanostructures

    PubMed Central

    Cochrane, K. A.; Schiffrin, A.; Roussy, T. S.; Capsoni, M.; Burke, S. A.

    2015-01-01

    Organic semiconductor devices rely on the movement of charge at and near interfaces, making an understanding of energy level alignment at these boundaries an essential element of optimizing materials for electronic and optoelectronic applications. Here we employ low temperature scanning tunneling microscopy and spectroscopy to investigate a model system: two-dimensional nanostructures of the prototypical organic semiconductor, PTCDA (3,4,9,10-perylenetetracarboxylic dianhydride) adsorbed on NaCl (2 ML)/Ag(111). Pixel-by-pixel scanning tunneling spectroscopy allows mapping of occupied and unoccupied electronic states across these nanoislands with sub-molecular spatial resolution, revealing strong electronic differences between molecules at the edges and those in the centre, with energy level shifts of up to 400 meV. We attribute this to the change in electrostatic environment at the boundaries of clusters, namely via polarization of neighbouring molecules. The observation of these strong shifts illustrates a crucial issue: interfacial energy level alignment can differ substantially from the bulk electronic structure in organic materials. PMID:26440933

  2. Crystal field parameters and energy levels scheme of trivalent chromium doped BSO

    NASA Astrophysics Data System (ADS)

    Petkova, P.; Andreici, E.-L.; Avram, N. M.

    2014-11-01

    The aim of this paper is to give an analysis of crystal field parameters and energy levels schemes for the above doped material, in order to give a reliable explanation for experimental data. The crystal field parameters have been modeled in the frame of Exchange Charge Model (ECM) of the crystal field theory, taken into account the geometry of systems, with actually site symmetry of the impurity ions. The effect of the charges of the ligands and covalence bonding between chromium cation and oxygen anions, in the cluster approach, also were taken into account. With the obtained values of the crystal field parameters we simulated the scheme of energy levels of chromium ions by diagonalizing the matrix of the Hamiltonian of the doped crystal. The obtained energy levels and estimated Racah parameters B and C were compared with the experimental spectroscopic data and discussed. Comparison with experiment shows that the results are quite satisfactory which justify the model and simulation scheme used for the title system.

  3. Energy transfer and energy level decay processes of Er3+ in water-free tellurite glass

    NASA Astrophysics Data System (ADS)

    Gomes, Laercio; Rhonehouse, Daniel; Nguyen, Dan T.; Zong, Jie; Chavez-Pirson, Arturo; Jackson, Stuart D.

    2015-12-01

    This report details the fundamental spectroscopic properties of a new class of water-free tellurite glasses studied for future applications in mid-infrared light generation. The fundamental excited state decay processes relating to the 4I11/2 → 4I13/2 transition in singly Er3+-doped Tellurium Zinc Lanthanum glass have been investigated using time-resolved fluorescence spectroscopy. The excited state dynamics was analyzed for Er2O3 concentrations between 0.5 mol% and 4 mol%. Selective laser excitation of the 4I11/2 energy level at 972 nm and selective laser excitation of the 4I13/2 energy level at 1485 nm has established that in a similar way to other Er3+-doped glasses, a strong energy-transfer upconversion by way of a dipole-dipole interaction between two excited erbium ions in the 4I13/2 level populates the 4I11/2 upper laser level of the 3 μm transition. The 4I13/2 and 4I11/2 energy levels emitted luminescence with peaks located at 1532 nm and 2734 nm respectively with luminescence efficiencies of 100% and 8% for the higher (4 mol.%) concentration sample. Results from numerical simulations showed that a population inversion is reached at a threshold pumping intensity of ∼57 kW cm-2 for a CW laser pump at 976 nm for [Er2O3] = 2 mol.%.

  4. Variational calculation of highly excited rovibrational energy levels of H2O2.

    PubMed

    Polyansky, Oleg L; Kozin, Igor N; Ovsyannikov, Roman I; Małyszek, Paweł; Koput, Jacek; Tennyson, Jonathan; Yurchenko, Sergei N

    2013-08-15

    Results are presented for highly accurate ab initio variational calculation of the rotation-vibration energy levels of H2O2 in its electronic ground state. These results use a recently computed potential energy surface and the variational nuclear-motion programs WARV4, which uses an exact kinetic energy operator, and TROVE, which uses a numerical expansion for the kinetic energy. The TROVE calculations are performed for levels with high values of rotational excitation, J up to 35. The purely ab initio calculations of the rovibrational energy levels reproduce the observed levels with a standard deviation of about 1 cm(-1), similar to that of the J = 0 calculation, because the discrepancy between theory and experiment for rotational energies within a given vibrational state is substantially determined by the error in the vibrational band origin. Minor adjustments are made to the ab initio equilibrium geometry and to the height of the torsional barrier. Using these and correcting the band origins using the error in J = 0 states lowers the standard deviation of the observed-calculated energies to only 0.002 cm(-1) for levels up to J = 10 and 0.02 cm(-1) for all experimentally known energy levels, which extend up to J = 35. PMID:23611762

  5. The program LOPT for least-squares optimization of energy levels

    NASA Astrophysics Data System (ADS)

    Kramida, A. E.

    2011-02-01

    The article describes a program that solves the least-squares optimization problem for finding the energy levels of a quantum-mechanical system based on a set of measured energy separations or wavelengths of transitions between those energy levels, as well as determining the Ritz wavelengths of transitions and their uncertainties. The energy levels are determined by solving the matrix equation of the problem, and the uncertainties of the Ritz wavenumbers are determined from the covariance matrix of the problem. Program summaryProgram title: LOPT Catalogue identifier: AEHM_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEHM_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 19 254 No. of bytes in distributed program, including test data, etc.: 427 839 Distribution format: tar.gz Programming language: Perl v.5 Computer: PC, Mac, Unix workstations Operating system: MS Windows (XP, Vista, 7), Mac OS X, Linux, Unix (AIX) RAM: 3 Mwords or more Word size: 32 or 64 Classification: 2.2 Nature of problem: The least-squares energy-level optimization problem, i.e., finding a set of energy level values that best fits the given set of transition intervals. Solution method: The solution of the least-squares problem is found by solving the corresponding linear matrix equation, where the matrix is constructed using a new method with variable substitution. Restrictions: A practical limitation on the size of the problem N is imposed by the execution time, which scales as N and depends on the computer. Unusual features: Properly rounds the resulting data and formats the output in a format suitable for viewing with spreadsheet editing software. Estimates numerical errors resulting from the limited machine precision. Running time: 1 s for N=100, or 60 s for N=400 on a typical PC.

  6. Energy Levels--An Important Factor in Identifying and Facilitating the Development of Giftedness in Young Children.

    ERIC Educational Resources Information Center

    Bergman, Jerry

    1979-01-01

    Research shows that there is a positive relationship between high energy levels and creativity and giftedness. To provide for the high energy levels, these children need to be kept busy at beneficial activities such as independent study, individualized programs, and/or enrichment classes. (Author/PHR)

  7. Self-energy-corrected electronic energy level alignment in molecular junctions and at interfaces with hybrid functionals

    NASA Astrophysics Data System (ADS)

    Kotiuga, Michele; Egger, David; Kronik, Leeor; Neaton, Jeffrey B.

    2015-03-01

    Accurate calculations of energy level alignment at complex interfaces are imperative for understanding a variety of transport and spectroscopy measurements, as well as for elucidating new interfacial electronic structure phenomena. However, standard approaches to such calculations, based on density functional theory (DFT), are well known to be deficient. In prior work on molecular junctions and physisorbed molecules on surfaces, an approximate GW approach, DFT+ Σ, has been successful in describing the conductance and level alignment of amine and pyridine terminated molecules on gold surfaces and in junctions. Here, via the use of hybrid functionals, we preform quantitative studies of the level alignment of thiol- and carbon-terminated phenyls on gold, where the formation of a strong chemical bond and presence of gateway states limit the validity of the DFT+ Σ approximation as currently formulated. We contrast these systems to prior work on weakly-coupled molecules, including bipyridine or phenyl-diamines. Additionally, we compute transmission functions using both DFT-PBE and DFT-HSE starting points and predict conductance and thermopower with these methods, comparing to experiments where possible. We acknowledge DOE, DOD, NERSC, ERC, ISF, and FWF.

  8. Level sequence and splitting identification of closely spaced energy levels by angle-resolved analysis of fluorescence light

    NASA Astrophysics Data System (ADS)

    Wu, Z. W.; Volotka, A. V.; Surzhykov, A.; Dong, C. Z.; Fritzsche, S.

    2016-06-01

    The angular distribution and linear polarization of the fluorescence light following the resonant photoexcitation is investigated within the framework of density matrix and second-order perturbation theory. Emphasis has been placed on "signatures" for determining the level sequence and splitting of intermediate (partially) overlapping resonances, if analyzed as a function of photon energy of incident light. Detailed computations within the multiconfiguration Dirac-Fock method have been performed, especially for the 1 s22 s22 p63 s ,Ji=1 /2 +γ1→(1s22 s 2 p63 s ) 13 p3 /2,J =1 /2 ,3 /2 →1 s22 s22 p63 s ,Jf=1 /2 +γ2 photoexcitation and subsequent fluorescence emission of atomic sodium. A remarkably strong dependence of the angular distribution and linear polarization of the γ2 fluorescence emission is found upon the level sequence and splitting of the intermediate (1s22 s 2 p63 s ) 13 p3 /2,J =1 /2 ,3 /2 overlapping resonances owing to their finite lifetime (linewidth). We therefore suggest that accurate measurements of the angular distribution and linear polarization might help identify the sequence and small splittings of closely spaced energy levels, even if they cannot be spectroscopically resolved.

  9. Experimental Energy Levels of HD18O and D_218O

    NASA Astrophysics Data System (ADS)

    Mikhailenko, S. N.; Naumenko, O. V.; Tashkun, S. A.; Liu, A.-W.; Hu, S.-M.

    2010-06-01

    Extended sets of experimental energy levels of HD18O and D_218O have been obtained as the result of the analysis of recent high-resolution spectra and previously reported data. Spectra of the enriched by deuterium and oxygen-18 water samples were recorded with a Bruker IFS 120HR spectrometer at room temperature in the 1000 - 9200 cm-1 range a,b for this purpose. The RITZ code h was used for analysis of the rotation-vibration transitions and the energy levels determination. New energy levels as well as comparison with previous experimental and theoretical studies will be presented. This work was supported by Grant nos. 06-03-39014 and 10-05-91176 of RFBR (Russia) and by Grant nos. 20903085 and 10574124 of NSFC (China). Work of SNM and SAT was also partly supported by CRDF (USA) Grant RUG1-2954-TO-09 and by RFBR. Grant 09-05-92508. A.-W. Liu et al., J. Mol. Spectrosc. 237, 149-162 (2006). H.-Y. Ni et al., Mol. Phys. 106, 1793-1801 (2008). J. Bellet et al., J. Mol. Spectrosc. 47, 388-402 (1973). J.W.C. Johns, J. Opt. Soc. Am. B2, 1340-1354 (1985). R.A. Toth, J. Mol. Spectrosc. 162, 41-54 (1993). W.F. Wang et al., J. Mol. Spectrosc. 176, 226-228 (1996). R.A. Toth, J. Mol. Structure, 742, 49-68 (2005). S.N. Mikhailenko et al., JQSRT, 110, 597-608 (2009). A. Liu et al., JQSRT, 110, 1781-1800 (2009). O.V. Naumenko et al., JQSRT, 111, 36-44 (2010).

  10. Calculation of energy levels, {ital E}1 transition amplitudes, and parity violation in francium

    SciTech Connect

    Dzuba, V.A.; Flambaum, V.V.; Sushkov, O.P.

    1995-05-01

    Many-body perturbation theory in the screened Coulomb interaction was used to calculate energy levels, {ital E}1 trransition amplitudes, and the parity-nonconserving (PNC) {ital E}1 amplitude of the 7{ital s}-8{ital s} transition in francium. The method takes into account the core-polarization effect, the second-order correlations, and the three dominating sequences of higher-order correlation diagrams: screening of the electron-electron interaction, particle-hole interaction, and the iterations of the self-energy operator. The result for the PNC amplitude for {sup 223}Fr is {ital E}1(7{ital s}-8{ital s})=(1.59{plus_minus}{similar_to}1%){times}10{sup {minus}10}{ital iea}{sub {ital B}}({minus}{ital Q}{sub {ital W}}/{ital N}), where {ital Q}{sub {ital W}} is the weak charge of the nucleus, {ital N}=136 is the number of neutrons, {ital e}={vert_bar}{ital e}{vert_bar} is the elementary charge, and {ital a}{sub {ital B}} is the Bohr radius. Our prediction for the position of the 8{ital s} energy level of Fr, which has not been measured yet, is 13 110 cm{sup {minus}1} below the limit of the continuous spectrum. The accuracy of the calculations was controlled by comparison with available experimental data and analogous calculations for cesium. It is estimated to be {similar_to}0.1% for the energy levels and {similar_to}1% for the transition amplitudes.

  11. Energy Levels and Transition Rates for GA-Like Ions (Xe XXIV-Pr XXIX)

    NASA Astrophysics Data System (ADS)

    El-Sayed, F.

    2015-07-01

    Energy levels, wavelengths, transition probabilities, oscillator strengths, and line strengths have been calculated for allowed electric dipole 4s 2 4p-4s4p 2 and 4s 2 4p-4s 2 4d transitions of Gallium-like ions from Z = 54 to 59, Xe XXIV, Cs XXV, Ba XXVI, La XXVII, Ce XXVIII, and Pr XXIX. The fully relativistic multiconfiguration Dirac-Fock method, taking into account both correlations within the n = 4 complex and the quantum electrodynamic effects, has been used in the calculations. The results have been compared with the available experimental and other theoretical results.

  12. Effects of Dietary Energy Levels on the Physiological Parameters and Reproductive Performance of Gestating Gilts

    PubMed Central

    Jin, S. S.; Jung, S. W.; Jang, J. C.; Chung, W. L.; Jeong, J. H.; Kim, Y. Y.

    2016-01-01

    This experiment was conducted to investigate the effects of dietary energy levels on the physiological parameters and reproductive performance of gestating first parity sows. A total of 52 F1 gilts (Yorkshire×Landrace) were allocated to 4 dietary treatments using a completely randomized design. Each treatment contained diets with 3,100, 3,200, 3,300, or 3,400 kcal of metabolizable energy (ME)/kg, and the daily energy intake of the gestating gilts in each treatment were 6,200, 6,400, 6,600, and 6,800 kcal of ME, respectively. During gestation, the body weight (p = 0.04) and weight gain (p = 0.01) of gilts linearly increased with increasing dietary energy levels. Backfat thickness was not affected at d110 of gestation by dietary treatments, but increased linearly (p = 0.05) from breeding to d 110 of gestation. There were no significant differences on the litter size or litter birth weight. During lactation, the voluntary feed intake of sows tended to decrease when the dietary energy levels increased (p = 0.08). No difference was observed in backfat thickness of the sows within treatments; increasing energy levels linearly decreased the body weight of sows (p<0.05) at d 21 of lactation and body weight gain during lactation (p<0.01). No significant differences were observed in the chemical compositions of colostrum and milk. Therefore, these results indicated that high-energy diets influenced the bodyweight and backfat thickness of sows during gestation and lactation. NRC (2012) suggested that the energy requirement of the gestation gilt should be between 6,678 and 7,932 kcal of ME/d. Similarly, our results suggested that 3,100 kcal of ME/kg is not enough to maintain the reproductive performance for gilts during gestation with 2 kg feed daily. Gilts in the treatment 3,400 kcal of ME/kg have a higher weaning number of piglets, but bodyweight and backfat loss were higher than other treatments during lactation. But bodyweight and backfat loss were higher than other

  13. Energy level alignment at the interfaces in a multilayer organic light-emitting diode structure

    NASA Astrophysics Data System (ADS)

    Olthof, S.; Meerheim, R.; Schober, M.; Leo, K.

    2009-06-01

    We use photoelectron spectroscopy to study the electronic structure and energy level alignment throughout an organic light-emitting diode. The structure under investigation is a state-of-the-art long-living red phosphorescent device composed of doped charge-injection layers, charge-blocking layers, and an emission layer. By consecutively building up the whole device, the key parameters of every interface are measured. Our results show that the doped layers have a significant influence on the device energetics, especially in controlling the built-in potential, and that there are mostly only small dipoles present at the interfaces of the intrinsic organic layers.

  14. COMPREHENSIVE OBSERVATIONS OF THE ULTRAVIOLET SPECTRUM AND IMPROVED ENERGY LEVELS FOR SINGLY IONIZED CHROMIUM (Cr II)

    SciTech Connect

    Sansonetti, Craig J.; Nave, Gillian; Reader, Joseph; Kerber, Florian

    2012-10-15

    We report new observations of the spectrum of singly ionized chromium (Cr II) in the region 1142-3954 A. The spectra were recorded with the National Institute of Standards and Technology 10.7 m normal-incidence vacuum spectrograph and FT700 vacuum ultraviolet Fourier transform spectrometer. More than 3600 lines are classified as transitions among 283 even and 368 odd levels. The new spectral data are used to re-optimize the energy levels, reducing their uncertainties by a typical factor of 20.

  15. Effects of Dietary Energy Levels on the Physiological Parameters and Reproductive Performance of Gestating Gilts.

    PubMed

    Jin, S S; Jung, S W; Jang, J C; Chung, W L; Jeong, J H; Kim, Y Y

    2016-07-01

    This experiment was conducted to investigate the effects of dietary energy levels on the physiological parameters and reproductive performance of gestating first parity sows. A total of 52 F1 gilts (Yorkshire×Landrace) were allocated to 4 dietary treatments using a completely randomized design. Each treatment contained diets with 3,100, 3,200, 3,300, or 3,400 kcal of metabolizable energy (ME)/kg, and the daily energy intake of the gestating gilts in each treatment were 6,200, 6,400, 6,600, and 6,800 kcal of ME, respectively. During gestation, the body weight (p = 0.04) and weight gain (p = 0.01) of gilts linearly increased with increasing dietary energy levels. Backfat thickness was not affected at d110 of gestation by dietary treatments, but increased linearly (p = 0.05) from breeding to d 110 of gestation. There were no significant differences on the litter size or litter birth weight. During lactation, the voluntary feed intake of sows tended to decrease when the dietary energy levels increased (p = 0.08). No difference was observed in backfat thickness of the sows within treatments; increasing energy levels linearly decreased the body weight of sows (p<0.05) at d 21 of lactation and body weight gain during lactation (p<0.01). No significant differences were observed in the chemical compositions of colostrum and milk. Therefore, these results indicated that high-energy diets influenced the bodyweight and backfat thickness of sows during gestation and lactation. NRC (2012) suggested that the energy requirement of the gestation gilt should be between 6,678 and 7,932 kcal of ME/d. Similarly, our results suggested that 3,100 kcal of ME/kg is not enough to maintain the reproductive performance for gilts during gestation with 2 kg feed daily. Gilts in the treatment 3,400 kcal of ME/kg have a higher weaning number of piglets, but bodyweight and backfat loss were higher than other treatments during lactation. But bodyweight and backfat loss were higher than other

  16. Energy levels and lifetimes of Nd IV, Pm IV, Sm IV, and Eu IV

    SciTech Connect

    Dzuba, V. A.; Safronova, U. I.; Johnson, W. R.

    2003-09-01

    To address the shortage of experimental data for electron spectra of triply ionized rare-earth elements we have calculated energy levels and lifetimes of 4f{sup n+1} and 4f{sup n}5d configurations of Nd IV (n=2), Pm IV (n=3), Sm IV (n=4), and Eu IV (n=5) using Hartree-Fock and configuration-interaction methods. To control the accuracy of our calculations we also performed similar calculations for Pr III, Nd III, and Sm III, for which experimental data are available. The results are important, in particular, for physics of magnetic garnets.

  17. Spectra, energy levels, and energy transition of lanthanide complexes with cinnamic acid and its derivatives.

    PubMed

    Zhou, Kaining; Feng, Zhongshan; Shen, Jun; Wu, Bing; Luo, Xiaobing; Jiang, Sha; Li, Li; Zhou, Xianju

    2016-04-01

    High resolution spectra and luminescent lifetimes of 6 europium(III)-cinnamic acid complex {[Eu2L6(DMF)(H2O)]·nDMF·H2O}m (L=cinnamic acid I, 4-methyl-cinnamic acid II, 4-chloro-cinnamic acid III, 4-methoxy-cinnamic acid IV, 4-hydroxy-cinnamic acid V, 4-nitro-cinnamic acid VI; DMF=N, N-dimethylformamide, C3H7NO) were recorded from 8 K to room temperature. The energy levels of Eu(3+) in these 6 complexes are obtained from the spectra analysis. It is found that the energy levels of the central Eu(3+) ions are influenced by the nephelauxetic effect, while the triplet state of ligand is lowered by the p-π conjugation effect of the para-substituted functional groups. The best energy matching between the ligand triplet state and the central ion excited state is found in complex I. While the other complexes show poorer matching because the gap of (5)D0 and triplet state contracts. PMID:26802538

  18. K-shell energy levels and radiative rates for transitions in Si ix

    NASA Astrophysics Data System (ADS)

    Wei, H. G.; Shi, J. R.; Wang, F. L.; Zhong, J. Y.; Liang, G. Y.; Zhao, G.

    2014-06-01

    Context. Accurate atomic data are needed to analyze the Si ix K-shell features in astrophysical X-ray spectra. Relative large discrepancies in the existing atomic data have impeded this progress. Aims: We present the accurate Si ix K-shell transition data, including K-shell energy levels, wavelengths, radiative rates, and oscillator strengths. Methods: The flexible atomic code (FAC), which is a fully relativistic atomic code with configuration interaction (CI) included, was employed to calculate these data. To investigate the CI effects, calculations with different configurations included were carried out. Results: The K-shell atomic data of Si ix transitions between 1s22s22p2, 1s22s2p3, 1s22p4, 1s2s22p3, 1s2s2p4, and 1s2p5 are reported. The accuracy of our data is demonstrated by comparing them with the available experimental measurements and theoretical calculations. The energy levels are accurate to 3.5 eV, the wavelengths to within 15 mÅ. For most transitions, the radiative rates an accuracy of 20%. The effects of CI from high-energy configurations were investigated as well. Full Tables 3 and 4 are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/566/A105

  19. Calculation of energy levels, lifetimes and radiative data for La XXIX to Sm XXXIV

    NASA Astrophysics Data System (ADS)

    Goyal, Arun; Khatri, Indu; Aggarwal, Sunny; Singh, A. K.; Mohan, Man

    2016-01-01

    We present the most comprehensive atomic data for La XXIX to Sm XXXIV with single electron excitation from M-shell to N-shell and N-shell to higher shells. We have presented energy levels, lifetimes and radiative data using Multi-configuration Dirac-Fock (MCDF) method for the lowest 27 states belonging to the configuration 3d104l (l = 0 , 1 , 2 , 3), 3d105l (l = 0 , 1 , 2 , 3 , 4), 3d106l (l = 0 , 1 , 2 , 3 , 4) and 3d94s2. We have also considered relativistic effects by incorporating quantum electrodynamics (QED) and Breit corrections. We have made comparisons of our presented results with available theoretical as well as experimental results and a good agreement is achieved. Further, we have also reported energy levels by performing distorted wave calculations with fully relativistic flexible atomic code (FAC). The calculations match well with MCDF results. Additionally, we have investigated the effect of nuclear charge on transition wavelength and radiative rates for strong Extreme Ultraviolet (EUV) transitions from n = 4 → 4. We believe that our reported data in this work may be useful in various applications of lanthanide ions related to broad area of research such as applied physics, laser physics and astrophysics etc.

  20. Energy levels, radiative rates, and lifetimes for transitions in W LVIII

    NASA Astrophysics Data System (ADS)

    Aggarwal, Kanti M.; Keenan, Francis P.

    2014-11-01

    Energy levels and radiative rates are reported for transitions in Cl-like W LVIII. Configuration interaction (CI) has been included among 44 configurations (generating 4978 levels) over a wide energy range up to 363 Ryd, and the general-purpose relativistic atomic structure package (GRASP) adopted for the calculations. Since no other results of comparable complexity are available, calculations have also been performed with the flexible atomic code (FAC), which help in assessing the accuracy of our results. Energies are listed for the lowest 400 levels (with energies up to ˜98 Ryd), which mainly belong to the 3s23p5, 3s3p6, 3s23p43d, 3s23p33d2, 3s3p43d2, 3s23p23d3, and 3p63d configurations, and radiative rates are provided for four types of transitions, i.e. E1, E2, M1, and M2. Our energy levels are assessed to be accurate to better than 0.5%, whereas radiative rates (and lifetimes) should be accurate to better than 20% for a majority of the strong transitions.

  1. Rovibrational bound states of neon trimer: quantum dynamical calculation of all eigenstate energy levels and wavefunctions.

    PubMed

    Yang, Benhui; Chen, Wenwu; Poirier, Bill

    2011-09-01

    Exact quantum dynamics calculations of the eigenstate energy levels and wavefunctions for all bound rovibrational states of the Ne(3) trimer (J = 0-18) have been performed using the ScalIT suite of parallel codes. These codes employ a combination of highly efficient methods, including phase-space optimized discrete variable representation, optimal separable basis, and preconditioned inexact spectral transform methods, together with an effective massive parallelization scheme. The Ne(3) energy levels and wavefunctions were computed using a pair-wise Lennard-Jones potential. Jacobi coordinates were used for the calculations, but to identify just those states belonging to the totally symmetric irreducible representation of the G(12) complete nuclear permutation-inversion group, wavefunctions were plotted in hyperspherical coordinates. "Horseshoe" states were observed above the isomerization barrier, but the horseshoe localization effect is weaker than in Ar(3). The rigid rotor model is found to be applicable for only the ground and first excited vibrational states at low J; fitted rotational constant values are presented. PMID:21913762

  2. Lorentz and CPT violating corrections to hydrogen energy levels at order 2̂

    NASA Astrophysics Data System (ADS)

    Adkins, Gregory; Yoder, Theodore

    2012-03-01

    The standard model extension (SME) is an effective field theory for physics beyond the SM that contains non-SM effects such as Lorentz and CPT violation. The SME effective Lagrangian contains a number of coefficients that describe new interactions. These as-yet-unobserved coefficients must be small. One approach for the detection of the SME coefficients is to calculate their effect on observable physical quantities, particularly those measureable to high precision. We have calculated the effect of the SME interactions on the energy levels of hydrogen. Starting from the field theory effective Lagrangian we have obtained the Hamiltonian of an SME-extended Dirac equation and have applied a Foldy-Wouthuysen expansion to obtain a non-relativistic effective Hamiltonian correct through terms quadratic in the momentum 3-vector. This Hamiltonian, at the order of interest, has the form H'=(Ai j+Bi j kσk)p^i p^j where Ai j and Bi j k are linear combinations of the SME parameters. We have evaluated the energy level corrections due to H', which are of order 2̂ times the SME coefficients. Constraints on the combinations of SME coefficients found in Ai j and Bi j k can be obtained by comparison with experimental results.

  3. Spectrum and energy levels of five-times ionized zirconium (Zr VI)

    NASA Astrophysics Data System (ADS)

    Reader, Joseph; Lindsay, Mark D.

    2016-02-01

    We carried out a new analysis of the spectrum of five-times-ionized zirconium Zr VI. For this we used sliding-spark discharges together with normal- and grazing-incidence spectrographs to observe the spectrum from 160 to 2000 Å. These observations showed that the analysis of this spectrum by Khan et al (1985 Phys. Scr. 31 837) contained a significant number of incorrect energy levels. We have now classified ˜420 lines as transitions between 23 even-parity levels 73 odd-parity levels. The 4s24p5, 4s4p6, 4s24p44d, 5s, 5d, 6s configurations are now complete, although a few levels of 4s24p45d are tentative. We determined Ritz-type wavelengths for ˜135 lines from the optimized energy levels. The uncertainties range from 0.0003 to 0.0020 Å. Hartree-Fock calculations and least-squares fits of the energy parameters to the observed levels were used to interpret the observed configurations. Oscillator strengths for all classified lines were calculated with the fitted parameters. The results are compared with values for the level energies, percentage compositions, and transition probabilities from recent ab initio theoretical calculations. The ionization energy was revised to 777 380 ± 300 cm-1 (96.38 ± 0.04 eV).

  4. Spectra, energy levels, and energy transition of lanthanide complexes with cinnamic acid and its derivatives

    NASA Astrophysics Data System (ADS)

    Zhou, Kaining; Feng, Zhongshan; Shen, Jun; Wu, Bing; Luo, Xiaobing; Jiang, Sha; Li, Li; Zhou, Xianju

    2016-04-01

    High resolution spectra and luminescent lifetimes of 6 europium(III)-cinnamic acid complex {[Eu2L6(DMF)(H2O)]·nDMF·H2O}m (L = cinnamic acid I, 4-methyl-cinnamic acid II, 4-chloro-cinnamic acid III, 4-methoxy-cinnamic acid IV, 4-hydroxy-cinnamic acid V, 4-nitro-cinnamic acid VI; DMF = N, N-dimethylformamide, C3H7NO) were recorded from 8 K to room temperature. The energy levels of Eu3 + in these 6 complexes are obtained from the spectra analysis. It is found that the energy levels of the central Eu3 + ions are influenced by the nephelauxetic effect, while the triplet state of ligand is lowered by the p-π conjugation effect of the para-substituted functional groups. The best energy matching between the ligand triplet state and the central ion excited state is found in complex I. While the other complexes show poorer matching because the gap of 5D0 and triplet state contracts.

  5. Energy levels, radiative rates, and lifetimes for transitions in W LVIII

    SciTech Connect

    Aggarwal, Kanti M. Keenan, Francis P.

    2014-11-15

    Energy levels and radiative rates are reported for transitions in Cl-like W LVIII. Configuration interaction (CI) has been included among 44 configurations (generating 4978 levels) over a wide energy range up to 363 Ryd, and the general-purpose relativistic atomic structure package (GRASP) adopted for the calculations. Since no other results of comparable complexity are available, calculations have also been performed with the flexible atomic code (FAC), which help in assessing the accuracy of our results. Energies are listed for the lowest 400 levels (with energies up to ∼98 Ryd), which mainly belong to the 3s{sup 2}3p{sup 5}, 3s3p{sup 6}, 3s{sup 2}3p{sup 4}3d, 3s{sup 2}3p{sup 3}3d{sup 2}, 3s3p{sup 4}3d{sup 2}, 3s{sup 2}3p{sup 2}3d{sup 3}, and 3p{sup 6}3d configurations, and radiative rates are provided for four types of transitions, i.e. E1, E2, M1, and M2. Our energy levels are assessed to be accurate to better than 0.5%, whereas radiative rates (and lifetimes) should be accurate to better than 20% for a majority of the strong transitions.

  6. A spectral-Lagrangian Boltzmann solver for a multi-energy level gas

    SciTech Connect

    Munafò, Alessandro; Haack, Jeffrey R.; Gamba, Irene M.; Magin, Thierry E.

    2014-05-01

    In this paper a spectral-Lagrangian method is proposed for the full, non-linear Boltzmann equation for a multi-energy level gas typical of a hypersonic re-entry flow. Internal energy levels are treated as separate species and inelastic collisions (leading to internal energy excitation and relaxation) are accounted for. The formulation developed can also be used for the case of a gas mixture made of monatomic gases without internal energy (where only elastic collisions occur). The advantage of the spectral-Lagrangian method lies in the generality of the algorithm in use for the evaluation of the elastic and inelastic collision operators, as well as the conservation of mass, momentum and energy during collisions. The latter is realized through the solution of constrained optimization problems. The computational procedure is based on the Fourier transform of the partial elastic and inelastic collision operators and exploits the fact that these can be written as weighted convolutions in Fourier space with no restriction on the cross-section model. The feasibility of the proposed approach is demonstrated through numerical examples for both space homogeneous and in-homogeneous problems. Computational results are compared with those obtained by means of the DSMC method in order to assess the accuracy of the proposed spectral-Lagrangian method.

  7. Energy levels, radiative rates and electron impact excitation rates for transitions in C III

    NASA Astrophysics Data System (ADS)

    Aggarwal, Kanti M.; Keenan, Francis P.

    2015-06-01

    We report energy levels, radiative rates (A-values) and lifetimes for the astrophysically important Be-like ion C III. For the calculations, 166 levels belonging to the n ≤ 5 configurations are considered and the GRASP (General-purpose Relativistic Atomic Structure Package) is adopted. Einstein A-coefficients are provided for all E1, E2, M1 and M2 transitions, while lifetimes are compared with available measurements as well as theoretical results, and no large discrepancies noted. Our energy levels are assessed to be accurate to better than 1 per cent for a majority of levels, and A-values to better than 20 per cent for most transitions. Collision strengths are also calculated, for which the Dirac Atomic R-matrix Code (DARC) is used. A wide energy range, up to 21 Ryd, is considered and resonances resolved in a fine energy mesh in the thresholds region. The collision strengths are subsequently averaged over a Maxwellian velocity distribution to determine effective collision strengths up to a temperature of 8.0 × 105 K, sufficient for most astrophysical applications. Our data are compared with the recent R-matrix calculations of Fernández-Menchero et al., and significant differences (up to over an order of magnitude) are noted for several transitions over the complete temperature range of the results.

  8. A new classification of the amino acid side chains based on doublet acceptor energy levels.

    PubMed Central

    Sneddon, S F; Morgan, R S; Brooks, C L

    1988-01-01

    We describe a new classification of the amino acid side chains based on the potential energy level at which each will accept an extra (doublet) electron. The doublet acceptor energy level, and the doublet acceptor orbital were calculated using semiempirical INDO/2-UHF molecular orbital theory. The results of these calculations show that the side chains fall into four groups. We have termed these groups repulsive, insulating, semiconducting, and attractive in accordance with where each lies on the relative energy scale. We use this classification to examine the role of residues between the donor and acceptor in modulating the rate and mechanism of electron transfer in proteins. With the calculated acceptor levels, we construct a potential barrier for those residues between the donor and acceptor. It is the area beneath this barrier that determines the decay of electronic coupling between donor and acceptor, and thus the transfer rate. We have used this schematic approach to characterize the four electron transfer pathways in myoglobin recently studied by Mayo et al. (Mayo, S.L., W.R. Ellis, R.J. Crutchley, and H.B. Gray. 1986. Science [Wash. DC]. 233:948-952). PMID:3342271

  9. THE SPECTRUM OF THORIUM FROM 250 nm TO 5500 nm: RITZ WAVELENGTHS AND OPTIMIZED ENERGY LEVELS

    SciTech Connect

    Redman, Stephen L.; Nave, Gillian; Sansonetti, Craig J.

    2014-03-01

    We have made precise observations of a thorium-argon hollow cathode lamp emission spectrum in the region between 350 nm and 1175 nm using a high-resolution Fourier transform spectrometer. Our measurements are combined with results from seven previously published thorium line lists to re-optimize the energy levels of neutral, singly, and doubly ionized thorium (Th I, Th II, and Th III). Using the optimized level values, we calculate accurate Ritz wavelengths for 19, 874 thorium lines between 250 nm and 5500 nm (40, 000 cm{sup –1} to 1800 cm{sup –1}). We have also found 102 new thorium energy levels. A systematic analysis of previous measurements in light of our new results allows us to identify and propose corrections for systematic errors in Palmer and Engleman and typographical errors and incorrect classifications in Kerber et al. We also found a large scatter with respect to the thorium line list of Lovis and Pepe. We anticipate that our Ritz wavelengths will lead to improved measurement accuracy for current and future spectrographs that make use of thorium-argon or thorium-neon lamps as calibration standards.

  10. Enzymatic versus inorganic oxygen reduction catalysts: comparison of the energy levels in a free-energy scheme.

    PubMed

    Kjaergaard, Christian H; Rossmeisl, Jan; Nørskov, Jens K

    2010-04-19

    In this paper, we present a method to directly compare the energy levels of intermediates in enzymatic and inorganic oxygen reduction catalysts. We initially describe how the energy levels of a Pt(111) catalyst, operating at pH = 0, are obtained. By a simple procedure, we then convert the energy levels of cytochrome c oxidase (CcO) models obtained at physiological pH = 7 to the energy levels at pH = 0, which allows for comparison. Furthermore, we illustrate how different bias voltages will affect the free-energy landscapes of the catalysts. This allows us to determine the so-called theoretical overpotential of each system, which is shown to be significantly lower for the enzymatic catalysts compared to the inorganic Pt(111) catalyst. Finally, we construct theoretical polarization curves for the CcO models, in order to illustrate the effect of the low overpotentials on turnover rates per site. PMID:20380458

  11. SPECTRUM AND ENERGY LEVELS OF Pr{sup 3+} IN ThBr{sub 4}

    SciTech Connect

    Conway, J. G.; Krupa, J. C.; Delamoye, P.; Genet, M.

    1980-06-01

    The strong features in the absorption spectrum and the laser excited fluorescence spectrum have been interpreted as arising from levels of Pr{sup 3+} in the D{sub 2d} symmetry site of ThBr{sub 4} . 43 energy levels have been fitted to the parameters with an RMS deviation of 61 cm{sup -1}. The values of the crystal field parameters are. B{sub 0}{sup 2} = 260.0 cm {sup -1}, B{sub 0}{sup 4} = - 644.2 cm{sup -1}, B{sub 4}{sup 4} = 929.2 cm{sup -1}, B{sub 0}{sup 6} = 1089.0 cm{sup -1} and B{sub 4}{sup 6} = 240.6 cm{sup -1}. The presence of other crystal symmetry sites is observed.

  12. Energy level alignment at the methylammonium lead iodide/copper phthalocyanine interface

    SciTech Connect

    Chen, Shi; Goh, Teck Wee; Sum, Tze Chien E-mail: Tzechien@ntu.edu.sg; Sabba, Dharani; Chua, Julianto; Mathews, Nripan; Huan, Cheng Hon Alfred E-mail: Tzechien@ntu.edu.sg

    2014-08-01

    The energy level alignment at the CH{sub 3}NH{sub 3}PbI{sub 3}/copper phthalocyanine (CuPc) interface is investigated by X-ray photoelectron spectroscopy (XPS) and ultraviolet photoelectron spectroscopy (UPS). XPS reveal a 0.3 eV downward band bending in the CuPc film. UPS validate this finding and further reveal negligible interfacial dipole formation – verifying the viability of vacuum level alignment. The highest occupied molecular orbital of CuPc is found to be closer to the Fermi level than the valance band maximum of CH{sub 3}NH{sub 3}PbI{sub 3}, facilitating hole transfer from CH{sub 3}NH{sub 3}PbI{sub 3} to CuPc. However, subsequent hole extraction from CuPc may be impeded by the downward band bending in the CuPc layer.

  13. Impurity effects on energy levels and far-infrared spectra of nanorings

    NASA Astrophysics Data System (ADS)

    Hui, Pan; Jia-Lin, Zhu

    2003-11-01

    The effects of a positively charged impurity on the energy levels and far-infrared spectra of one and two electrons in semiconductor nanorings under magnetic fields are studied. The effects of the nanoring size and the impurity position are also discussed. It is shown that the electron-electron interaction and electron-impurity one in nanorings are strongly dependent on the nanoring size and the impurity position. Based on the studies of the impurity and field effects, the impurity-induced Aharonov-Bohm oscillations of the far-infrared spectra are found. The results predict a possibility of observing phenomena related to electron-impurity interaction in a nanoring in the future.

  14. Determination of energy level alignment at metal/molecule interfaces by in-device electrical spectroscopy

    NASA Astrophysics Data System (ADS)

    Gobbi, M.; Pietrobon, L.; Atxabal, A.; Bedoya-Pinto, A.; Sun, X.; Golmar, F.; Llopis, R.; Casanova, F.; Hueso, L. E.

    2014-06-01

    The energetics of metal/molecular semiconductor interfaces plays a fundamental role in organic electronics, determining the performance of very diverse devices. So far, information about the energy level alignment has been most commonly gained by spectroscopy techniques that typically require experimental conditions far from the real device operation. Here we demonstrate that a simple three-terminal device allows the acquisition of spectroscopic information about the metal/molecule energy alignment in real operative condition. As a proof of principle, we employ the proposed device to measure the energy barrier height between different clean metals and C60 molecules and we recover typical results from photoemission spectroscopy. The device is designed to inject a hot electron current directly into the molecular level devoted to charge transport, disentangling the contributions of both the interface and the bulk to the device total resistance, with important implications for spintronics and low-temperature physics.

  15. Wave energy level and geographic setting correlate with Florida beach water quality.

    PubMed

    Feng, Zhixuan; Reniers, Ad; Haus, Brian K; Solo-Gabriele, Helena M; Kelly, Elizabeth A

    2016-03-15

    Many recreational beaches suffer from elevated levels of microorganisms, resulting in beach advisories and closures due to lack of compliance with Environmental Protection Agency guidelines. We conducted the first statewide beach water quality assessment by analyzing decadal records of fecal indicator bacteria (enterococci and fecal coliform) levels at 262 Florida beaches. The objectives were to depict synoptic patterns of beach water quality exceedance along the entire Florida shoreline and to evaluate their relationships with wave condition and geographic location. Percent exceedances based on enterococci and fecal coliform were negatively correlated with both long-term mean wave energy and beach slope. Also, Gulf of Mexico beaches exceeded the thresholds significantly more than Atlantic Ocean ones, perhaps partially due to the lower wave energy. A possible linkage between wave energy level and water quality is beach sand, a pervasive nonpoint source that tends to harbor more bacteria in the low-wave-energy environment. PMID:26892203

  16. Charge separation at nanoscale interfaces: Energy-level alignment including two-quasiparticle interactions

    SciTech Connect

    Li, Huashan; Lin, Zhibin; Lusk, Mark T. Wu, Zhigang

    2014-10-21

    The universal and fundamental criteria for charge separation at interfaces involving nanoscale materials are investigated. In addition to the single-quasiparticle excitation, all the two-quasiparticle effects including exciton binding, Coulomb stabilization, and exciton transfer are considered, which play critical roles on nanoscale interfaces for optoelectronic applications. We propose a scheme allowing adding these two-quasiparticle interactions on top of the single-quasiparticle energy level alignment for determining and illuminating charge separation at nanoscale interfaces. Employing the many-body perturbation theory based on Green's functions, we quantitatively demonstrate that neglecting or simplifying these crucial two-quasiparticle interactions using less accurate methods is likely to predict qualitatively incorrect charge separation behaviors at nanoscale interfaces where quantum confinement dominates.

  17. Accuracy of analytic energy level formulas applied to hadronic spectroscopy of heavy mesons

    NASA Technical Reports Server (NTRS)

    Badavi, Forooz F.; Norbury, John W.; Wilson, John W.; Townsend, Lawrence W.

    1988-01-01

    Linear and harmonic potential models are used in the nonrelativistic Schroedinger equation to obtain article mass spectra for mesons as bound states of quarks. The main emphasis is on the linear potential where exact solutions of the S-state eigenvalues and eigenfunctions and the asymptotic solution for the higher order partial wave are obtained. A study of the accuracy of two analytical energy level formulas as applied to heavy mesons is also included. Cornwall's formula is found to be particularly accurate and useful as a predictor of heavy quarkonium states. Exact solution for all partial waves of eigenvalues and eigenfunctions for a harmonic potential is also obtained and compared with the calculated discrete spectra of the linear potential. Detailed derivations of the eigenvalues and eigenfunctions of the linear and harmonic potentials are presented in appendixes.

  18. Energy level alignment at the methylammonium lead iodide/copper phthalocyanine interface

    NASA Astrophysics Data System (ADS)

    Chen, Shi; Goh, Teck Wee; Sabba, Dharani; Chua, Julianto; Mathews, Nripan; Huan, Cheng Hon Alfred; Sum, Tze Chien

    2014-08-01

    The energy level alignment at the CH3NH3PbI3/copper phthalocyanine (CuPc) interface is investigated by X-ray photoelectron spectroscopy (XPS) and ultraviolet photoelectron spectroscopy (UPS). XPS reveal a 0.3 eV downward band bending in the CuPc film. UPS validate this finding and further reveal negligible interfacial dipole formation - verifying the viability of vacuum level alignment. The highest occupied molecular orbital of CuPc is found to be closer to the Fermi level than the valance band maximum of CH3NH3PbI3, facilitating hole transfer from CH3NH3PbI3 to CuPc. However, subsequent hole extraction from CuPc may be impeded by the downward band bending in the CuPc layer.

  19. Determination of energy level alignment at metal/molecule interfaces by in-device electrical spectroscopy.

    PubMed

    Gobbi, M; Pietrobon, L; Atxabal, A; Bedoya-Pinto, A; Sun, X; Golmar, F; Llopis, R; Casanova, F; Hueso, L E

    2014-01-01

    The energetics of metal/molecular semiconductor interfaces plays a fundamental role in organic electronics, determining the performance of very diverse devices. So far, information about the energy level alignment has been most commonly gained by spectroscopy techniques that typically require experimental conditions far from the real device operation. Here we demonstrate that a simple three-terminal device allows the acquisition of spectroscopic information about the metal/molecule energy alignment in real operative condition. As a proof of principle, we employ the proposed device to measure the energy barrier height between different clean metals and C60 molecules and we recover typical results from photoemission spectroscopy. The device is designed to inject a hot electron current directly into the molecular level devoted to charge transport, disentangling the contributions of both the interface and the bulk to the device total resistance, with important implications for spintronics and low-temperature physics. PMID:24946715

  20. Energy levels and spectral lines in the X-ray spectra of highly charged W XLIV

    NASA Astrophysics Data System (ADS)

    Hao, Liang-Huan; Kang, Xiao-Ping

    2014-07-01

    The multi-configuration Dirac-Hartree-Fock method is employed to calculate the fine-structure energy levels, wavelengths, transition probabilities, and oscillator strengths for electric dipole allowed (E1) and forbidden (M1, E2, M2) lines for the 4 s 24 p and 4 s4 p 2 configurations of W XLIV. The valence-valence and core-valence correlation effects are accounted for in a systematic way. Breit interactions and quantum electrodynamics (QED) effects are estimated in subsequent relativistic configuration interaction (CI) calculations. The present results are in good agreement with other available theoretical and experimental values, and we predict new data for several levels where no other theoretical and/or experimental results are available, precise measurements are clearly needed here.

  1. Multiphoton transitions between energy levels in a current-biased Josephson tunnel junction.

    PubMed

    Wallraff, A; Duty, T; Lukashenko, A; Ustinov, A V

    2003-01-24

    The escape of a current-biased Josephson tunnel junction from the zero-voltage state in the presence of weak microwave radiation is investigated experimentally at low temperatures. The measurements of the junction switching current distribution indicate the macroscopic quantum tunneling of the phase below a crossover temperature of T small star, filled approximately 280 mK. At temperatures below T small star, filled we observe both single-photon and multiphoton transitions between the junction energy levels by applying microwave radiation in the frequency range between 10 and 38 GHz to the junction. These observations reflect the anharmonicity of the junction potential containing only a small number of levels. PMID:12570519

  2. Spectrum and energy levels of the sodiumlike ion Sr/sup 27+/

    SciTech Connect

    Reader, J.

    1986-06-01

    The spectrum of Sr/sup 27+/ was observed with a laser-produced plasma and a 2.2-m grazing-incidence spectrograph in the region 12--160 A-circle. From the identification of 37 lines, a system of 27 energy levels of the type 2p-italic/sup 6/n-italicl-italic was determined. The level system includes the configurations n-italics-italic(n-italic = 3-5), n-italicp-italic(n-italic = 3-6), n-italicd-italic(n-italic = 3-7), n-italicf-italic(n-italic = 4-6), and 5g-italic. The ionization energy is determined as 11 188200 +- 1000 cm/sup -1/ (1387.16 +- 0.12 eV).

  3. Energy levels and radiative rates for Cr-like Cu VI and Zn VII

    NASA Astrophysics Data System (ADS)

    Aggarwal, K. M.; Bogdanovich, P.; Keenan, F. P.; Kisielius, R.

    2016-09-01

    Energy levels and radiative rates (A-values) for transitions in Cr-like Cu VI and Zn VII are reported. These data are determined in the quasi-relativistic approach (QR), by employing a very large configuration interaction (CI) expansion which is highly important for these ions. No radiative rates are available in the literature to compare with our results, but our calculated energies are in close agreement with those compiled by NIST and other available theoretical data, for a majority of the levels. The A-values (and resultant lifetimes) are listed for all significantly contributing E1, E2 and M1 radiative transitions among the energetically lowest 322 levels of each ion.

  4. S-matrix Calculations of Energy Levels of the Lithium Isoelectronic Sequence

    SciTech Connect

    sapirstein, J; Cheng, K T

    2010-11-02

    A QED approach to the calculation of the spectra of the lithium isoelectronic sequence is implemented. A modified Furry representation based on the Kohn-Sham potential is used to evaluate all one- and two-photon diagrams with the exception of the two-loop Lamb shift. Three-photon diagrams are estimated with Hamiltonian methods. After incorporating recent calculations of the two-loop Lamb shift and recoil corrections a comprehensive tabulation of the 2s, 2p{sub 1/2} and 2p{sub 3/2} energy levels as well as the 2s - 2p{sub 1/2} and 2s - 2p{sub 3/2} transition energies for Z = 10 - 100 is presented.

  5. Energy levels and radiative rates for transitions in Cr-like Co IV and Ni V

    NASA Astrophysics Data System (ADS)

    Aggarwal, K. M.; Bogdanovich, P.; Karpuškienė, R.; Keenan, F. P.; Kisielius, R.; Stancalie, V.

    2016-01-01

    We report calculations of energy levels and radiative rates (A-values) for transitions in Cr-like Co IV and Ni V. The quasi-relativistic Hartree-Fock (QRHF) code is adopted for calculating the data although GRASP (general-purpose relativistic atomic structure package) and flexible atomic code (FAC) have also been employed for comparison purposes. No radiative rates are available in the literature to compare with our results, but our calculated energies are in close agreement with those compiled by NIST for a majority of the levels. However, there are discrepancies for a few levels of up to 3%. The A-values are listed for all significantly contributing E1, E2 and M1 transitions, and the corresponding lifetimes reported, although unfortunately no previous theoretical or experimental results exist to compare with our data.

  6. Calculation of energy levels and transition amplitudes for barium and radium.

    SciTech Connect

    Dzuba, V. A.; Flambaum, V. V.; Physics; Univ. of New South Wales

    2007-01-01

    The radium atom is a promising system for studying parity and time invariance violating weak interactions. However, available experimental spectroscopic data for radium are insufficient for designing an optimal experimental setup. We calculate the energy levels and transition amplitudes for radium states of significant interest. Forty states corresponding to all possible configurations consisting of the 7s, 7p and 6d single-electron states as well as the states of the 7s8s, 7s8p and 7s7d configurations have been calculated. The energies of ten of these states corresponding to the 6d{sup 2}, 7s8s, 7p{sup 2} and 6d7p configurations are not known from experiment. Calculations for barium are used to control the accuracy.

  7. Energy levels and radiative transition rates for Ge XXXI, As XXXII, and Se XXXIII

    SciTech Connect

    Aggarwal, Sunny Singh, J.; Jha, A.K.S.; Mohan, Man

    2014-07-15

    Fine-structure energies of the 67 levels belonging to the 1s{sup 2}, 1s 2l, 1s3l, 1s4l, 1s5l, and 1s6l configurations of Ge XXXI, As XXXII, and Se XXXIII have been calculated using the General-Purpose Relativistic Atomic Structure Package. In addition, radiative rates, oscillator strengths, transition wavelengths, and line strengths have been calculated for all electric dipole, magnetic dipole, electric quadrupole, and magnetic quadrupole transitions among these levels. Lifetimes are also presented for all excited levels of these three ions. We have compared our results with the results available in the literature and the accuracy of the data is assessed. We predict new energy levels, oscillator strengths, and transition probabilities where no other theoretical or experimental results are available, which will form the basis for future experimental work.

  8. Energy levels, radiative rates, and lifetimes for transitions in W XL

    SciTech Connect

    Aggarwal, Kanti M. Keenan, Francis P.

    2014-11-15

    Energy levels and radiative rates are reported for transitions in Br-like tungsten, W XL, calculated with the general-purpose relativistic atomic structure package (GRASP). Configuration interaction (CI) has been included among 46 configurations (generating 4215 levels) over a wide energy range up to 213 Ryd. However, for conciseness results are only listed for the lowest 360 levels (with energies up to ∼43 Ryd), which mainly belong to the 4s{sup 2}4p{sup 5},4s{sup 2}4p{sup 4}4d,4s{sup 2}4p{sup 4}4f,4s4p{sup 6},4p{sup 6}4d,4s4p{sup 5}4d,4s{sup 2}4p{sup 3}4d{sup 2}, and 4s{sup 2}4p{sup 3}4d4f configurations, and provided for four types of transitions, E1, E2, M1, and M2. Comparisons are made with existing (but limited) results. However, to fully assess the accuracy of our data, analogous calculations have been performed with the flexible atomic code, including an even larger CI than in GRASP. Our energy levels are estimated to be accurate to better than 0.02 Ryd, whereas results for radiative rates (and lifetimes) should be accurate to better than 20% for a majority of the strong transitions.

  9. Energy levels and transition rates for the boron isoelectronic sequence: Si X, Ti XVIII - Cu XXV

    NASA Astrophysics Data System (ADS)

    Jönsson, P.; Ekman, J.; Gustafsson, S.; Hartman, H.; Karlsson, L. B.; du Rietz, R.; Gaigalas, G.; Godefroid, M. R.; Froese Fischer, C.

    2013-11-01

    Relativistic configuration interaction (RCI) calculations are performed for 291 states belonging to the configurations 1s22s22p, 1s22s2p2, 1s22p3, 1s22s23l, 1s22s2p3l, 1s22p23l, 1s22s24l', 1s22s2p4l', and 1s22p24l' (l = 0,1,2 and l' = 0,1,2,3) in boron-like ions Si X and Ti XVIII to Cu XXV. Electron correlation effects are represented in the wave functions by large configuration state function (CSF) expansions. States are transformed from jj-coupling to LS-coupling, and the LS-percentage compositions are used for labeling the levels. Radiative electric dipole transition rates are given for all ions, leading to massive data sets. Calculated energy levels are compared with other theoretical predictions and crosschecked against the Chianti database, NIST recommended values, and other observations. The accuracy of the calculations are high enough to facilitate the identification of observed spectral lines. Research supported in part by the Swedish Research council and the Swedish Institute. Part of this work was supported by the Communauté française of Belgium, the Belgian National Fund for Scientific Research (FRFC/IISN Convention) and by the IUAP-Belgian State Science Policy (BriX network P7/12).Tables of energy levels and transition rates (Tables 3-19) are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/559/A100

  10. Density Visualization

    ERIC Educational Resources Information Center

    Keiter, Richard L.; Puzey, Whitney L.; Blitz, Erin A.

    2006-01-01

    Metal rods of high purity for many elements are now commercially available and may be used to construct a display of relative densities. We have constructed a display with nine metal rods (Mg, Al, Ti, V, Fe, Cu, Ag, Pb, and W) of equal mass whose densities vary from 1.74 to 19.3 g cm[superscript -3]. The relative densities of the metals may be…

  11. Wavelengths, energy levels and hyperfine structure of Mn II and Sc II.

    NASA Astrophysics Data System (ADS)

    Nave, Gillian; Pickering, Juliet C.; Townley-Smith, Keeley I. M.; Hala, .

    2015-08-01

    For many decades, the Atomic Spectroscopy Groups at the National Institute of Standards and Technology (NIST) and Imperial College London (ICL) have measured atomic data of astronomical interest. Our spectrometers include Fourier transform (FT) spectrometers at NIST and ICL covering the region 1350 Å to 5.5 μm and a 10.7-m grating spectrometer at NIST covering wavelengths from 300 - 5000 Å. Sources for these spectra include high-current continuous and pulsed hollow cathode (HCL) lamps, Penning discharges, and sliding spark discharges. Recent work has focused on the measurement and analysis of wavelengths, energy levels, and hyperfine structure (HFS) constants for iron-group elements. The analysis of FT spectra of Cr I, Mn I, and Mn II is being led by ICL and is described in a companion poster [1]. Current work being led by NIST includes the analysis of HFS in Mn II, analysis of Mn II in the vacuum ultraviolet, and a comprehensive analysis of Sc II.Comprehensive HFS constants for Mn II are needed for the interpretation of stellar spectra and incorrect abundances may be obtained when HFS is omitted. Holt et al. [2] have measured HFS constants for 59 levels of Mn II using laser spectroscopy. We used FT spectra of Mn/Ni and Mn/Cu HCLs covering wavelength ranges from 1350 Å to 5.4 μm to confirm 26 of the A constants of Holt et al. and obtain values for roughly 40 additional levels. We aim to obtain HFS constants for the majority of lines showing significant HFS that are observed in chemically-peculiar stars.Spectra of Sc HCLs have been recorded from 1800 - 6700 Å using a vacuum ultraviolet FT spectrometer at NIST. Additional measurements to cover wavelengths above 6700 Å and below 1800 Å are in progress. The spectra are being analyzed by NIST and Alighar Muslim University, India in order to derive improved wavelengths, energy levels, and hyperfine structure parameters.This work was partially supported by NASA, the STFC and PPARC (UK), the Royal Society of the UK

  12. Energy levels, transition probabilities, and electron impact excitations for La XXX

    SciTech Connect

    Zhong, J.Y. . E-mail: jyzhong@aphy.iphy.ac.cn; Zhao, G.; Zhang, J.

    2006-09-15

    energy levels, spontaneous radiative decay rates, and electron impact collision strengths are calculated for La XXX. The data refer to 107 fine-structure levels belonging to the configurations (1s{sup 2}2s{sup 2}2p{sup 6})3s{sup 2}3p{sup 6}3d{sup 10}, 3s{sup 2}3p{sup 6}3d{sup 9}4l, 3s{sup 2}3p{sup 5}3d{sup 10}4l, and 3s3p{sup 6}3d{sup 10}4l (l = s, p, d, f). The collision strengths are calculated with a 20-collision-energy grid in terms of the energy of the scattered electron between 10 and 10,000 eV by using the distorted-wave approximation. Effective collision strengths are obtained at seven electron temperatures: T {sub e} (eV) = 10, 100, 300, 500, 800, 1000, and 1500 by integrating the collision strengths over a Maxwellian electron distribution. Coupled with these atomic data, a hydrodynamic code MED103 can be used to simulate the Ni-like La X-ray laser at 8.8 nm.

  13. Energy levels fitting and crystal-field calculations of Nd3+ doped in GYSGG crystal

    NASA Astrophysics Data System (ADS)

    Gao, Jinyun; Zhang, Qingli; Sun, Dunlu; Luo, Jianqiao; Liu, Wenpeng; Yin, Shaotang

    2012-10-01

    The single crystal Nd3+-doped in GdY2Sc2Ga3O12 (Nd3+:GYSGG) was grown by Czochralski method successfully, and its absorption spectra was analyzed in a wider spectral wavelength range at 7.6 K and 300 K, respectively. The free-ions and crystal-field parameters were fitted to the experimental energy levels at 7.6 K and 300 K with the root mean square deviation of 11.25 and 12.48 cm-1, respectively. According to the crystal-field calculations, 116 levels of Nd3+ at 7.6 K and 114 levels of Nd3+ at 300 K were assigned. The fitting results of free-ions and crystal-field parameters were compared with those already reported of Nd3+:GSGG and Nd3+:YSAG. The results indicated that the free-ions parameters are similar to those of the Nd3+ in GYSGG, GSGG and YSAG crystals, and the crystal-field interaction of GSGG and YSAG is stronger than that of GYSGG, which results in the dual-wavelength properties of Nd3+:GYSGG crystal.

  14. Optically switchable transistor via energy-level phototuning in a bicomponent organic semiconductor

    NASA Astrophysics Data System (ADS)

    Orgiu, Emanuele; Crivillers, Núria; Herder, Martin; Grubert, Lutz; Pätzel, Michael; Frisch, Johannes; Pavlica, Egon; Duong, Duc T.; Bratina, Gvido; Salleo, Alberto; Koch, Norbert; Hecht, Stefan; Samorì, Paolo

    2012-08-01

    Organic semiconductors are suitable candidates for printable, flexible and large-area electronics. Alongside attaining an improved device performance, to confer a multifunctional nature to the employed materials is key for organic-based logic applications. Here we report on the engineering of an electronic structure in a semiconducting film by blending two molecular components, a photochromic diarylethene derivative and a poly(3-hexylthiophene) (P3HT) matrix, to attain phototunable and bistable energy levels for the P3HT's hole transport. As a proof-of-concept we exploited this blend as a semiconducting material in organic thin-film transistors. The device illumination at defined wavelengths enabled reversible tuning of the diarylethene's electronic states in the blend, which resulted in modulation of the output current. The device photoresponse was found to be in the microsecond range, and thus on a technologically relevant timescale. This modular blending approach allows for the convenient incorporation of various molecular components, which opens up perspectives on multifunctional devices and logic circuits.

  15. Interfacial energy level shifts in few-molecule clusters of the organic semiconductor PTCDA

    NASA Astrophysics Data System (ADS)

    Burke, Sarah; Cochrane, Katherine; Schiffrin, Agustin; Roussy, Tanya

    2014-03-01

    Detailed knowledge of the local electronic structure of organic semiconductors near interfaces is crucial for the understanding of a variety of electronic and optoelectronic applications of these emerging materials. However, organic molecules are highly sensitive to the local environment, which abruptly changes at an interface. Here, we present a study on the prototypical organic semiconductor PTCDA by scanning tunneling microscopy and spectroscopic mapping. Nanoscale clusters of varying size and geometry were probed on a bilayer NaCl film on Ag(111). The molecular states, while decoupled from the underlying metal surface, are relatively delocalized within these monolayer islands. Depending on the size of the cluster and arrangement of molecules within the cluster, edge molecules exhibit varying energy level shifts relative to the central molecules, both of which differ from the isolated molecule. For well ordered islands, this leads to a type-1 heterojunction, with a larger band gap at the edge of the cluster differing by as much as 0.5eV. In considering nanoscale structures within multicomponent device architectures, such internal heterostructures established by differences in the local environment are an important consideration, and could even be exploited.

  16. Energy levels distribution in supersaturated silicon with titanium for photovoltaic applications

    SciTech Connect

    Pérez, E. Castán, H.; García, H.; Dueñas, S.; Bailón, L.; Montero, D.; García-Hernansanz, R.; García-Hemme, E.; González-Díaz, G.; Olea, J.

    2015-01-12

    In the attempt to form an intermediate band in the bandgap of silicon substrates to give it the capability to absorb infrared radiation, we studied the deep levels in supersaturated silicon with titanium. The technique used to characterize the energy levels was the thermal admittance spectroscopy. Our experimental results showed that in samples with titanium concentration just under Mott limit there was a relationship among the activation energy value and the capture cross section value. This relationship obeys to the well known Meyer-Neldel rule, which typically appears in processes involving multiple excitations, like carrier capture/emission in deep levels, and it is generally observed in disordered systems. The obtained characteristic Meyer-Neldel parameters were Tmn = 176 K and kTmn = 15 meV. The energy value could be associated to the typical energy of the phonons in the substrate. The almost perfect adjust of all experimental data to the same straight line provides further evidence of the validity of the Meyer Neldel rule, and may contribute to obtain a deeper insight on the ultimate meaning of this phenomenon.

  17. Intranasal Insulin Suppresses Food Intake via Enhancement of Brain Energy Levels in Humans

    PubMed Central

    Jauch-Chara, Kamila; Friedrich, Alexia; Rezmer, Magdalena; Melchert, Uwe H.; G. Scholand-Engler, Harald; Hallschmid, Manfred; Oltmanns, Kerstin M.

    2012-01-01

    Cerebral insulin exerts anorexic effects in humans and animals. The underlying mechanisms, however, are not clear. Because insulin physiologically facilitates glucose uptake by most tissues of the body and thereby fosters intracellular energy supply, we hypothesized that intranasal insulin reduces food consumption via enhancement of the neuroenergetic level. In a double-blind, placebo–controlled, within-subject comparison, 15 healthy men (BMI 22.2 ± 0.37 kg/m2) aged 22–28 years were intranasally administered insulin (40 IU) or placebo after an overnight fast. Cerebral energy metabolism was assessed by 31P magnetic resonance spectroscopy. At 100 min after spray administration, participants consumed ad libitum from a test buffet. Our data show that intranasal insulin increases brain energy (i.e., adenosine triphosphate and phosphocreatine levels). Cerebral energy content correlates inversely with subsequent calorie intake in the control condition. Moreover, the neuroenergetic rise upon insulin administration correlates with the consecutive reduction in free-choice calorie consumption. Brain energy levels may therefore constitute a predictive value for food intake. Given that the brain synchronizes food intake behavior in dependence of its current energetic status, a future challenge in obesity treatment may be to therapeutically influence cerebral energy homeostasis. Intranasal insulin, after optimizing its application schema, seems a promising option in this regard. PMID:22586589

  18. Electromagnetic Shifts of Energy Levels of a Hydrogen Atom in Idealized Cavities.

    NASA Astrophysics Data System (ADS)

    Burzan, Dragisa

    Available from UMI in association with The British Library. Requires signed TDF. Energy level shifts are evaluated for the 2p-2s transition for a hydrogen atom in various confining geometries with idealized perfectly conducting metallic boundaries in all cases. The minimal coupling Hamiltonian formalism is employed in the non-relativistic approximation in the Coulomb gauge to calculate the level shifts. Bethe's work for the Lamb shift in free space for the hydrogen atom is used as the model for working out the transverse level shifts in the various confining geometries. The Stark effect arising from the interaction of an atom with its image in the metal is used to evaluate the longitudinal level shift. The analysis is carried out by first quantizing the electro-magnetic field in a general cavity after a discussion is presented in the introduction of the relation of this work to that of other authors on related topics. The theory is then developed in detail in the various special confining geometries starting with case of the parallelopiped and its limiting cases of two plates and one plate respectively. The confining geometries of a finite and infinite cylinder are considered next followed by that of sphere. Detailed numerical results are presented in each of the various special cases with graphs and tables after extensive computation. The conclusions of the thesis are summarized separately.

  19. The IUPAC Database of Rotational-Vibrational Energy Levels and Transitions of Water Isotopologues from Experiment and Theory

    NASA Astrophysics Data System (ADS)

    Császár, Attila G.; Furtenbacher, T.; Tennyson, Jonathan; Bernath, Peter F.; Brown, Linda R.; Campargue, Alain; Daumont, Ludovic; Gamache, Robert R.; Hodges, Joseph T.; Naumenko, Olga V.; Polyansky, Oleg L.; Rothman, Laurence S.; Vandaele, Ann Carine; Zobov, Nikolai F.

    2014-06-01

    The results of an IUPAC Task Group formed in 2004 on "A Database of Water Transitions from Experiment and Theory" (Project No. 2004-035-1-100) are presented. Energy levels and recommended labels involving exact and approximate quantum numbers for the main isotopologues of water in the gas phase, H216O, H218O, H217O, HD16O, HD18O, HD17O, D216O, D218O, and D217O, are determined from measured transition wavenumbers. The transition wavenumbers and energy levels are validated using the MARVEL (measured active rotational-vibrational energy levels) approach and first-principles nuclear motion computations. The extensive data, e.g., more than 200,000 transitions have been handled for H216O, including lines and levels that are required for analysis and synthesis of spectra, thermochemical applications, the construction of theoretical models, and the removal of spectral contamination by ubiquitous water lines. These datasets can also be used to assess where measurements are lacking for each isotopologue and to provide accurate frequencies for many yet-to-be measured transitions. The lack of high-quality frequency calibration standards in the near infrared is identified as an issue that has hindered the determination of high-accuracy energy levels at higher frequencies. The generation of spectra using the MARVEL energy levels combined with transition intensities computed using high accuracy ab initio dipole moment surfaces are discussed.

  20. Bone Density

    MedlinePlus

    ... bone health. It compares your bone density, or mass, to that of a healthy person who is ... Whether your osteoporosis treatment is working Low bone mass that is not low enough to be osteoporosis ...

  1. The influence of triplet energy levels of bridging ligands on energy transfer processes in Ir(III)/Eu(III) dyads.

    PubMed

    Jiang, Weili; Lou, Bin; Wang, Jianqiang; Lv, Hongbin; Bian, Zuqiang; Huang, Chunhui

    2011-11-21

    A series of N^N,O^O-bridging ligands based on substituted 1-(pyridin-2-yl)-3-methyl-5-pyrazolone and their corresponding heteroleptic iridium(III) complexes as well as Ir-Eu bimetallic complexes were synthesized and fully characterized. The influence of the triplet energy levels of the bridging ligands on the energy transfer (ET) process from the Ir(III) complexes to Eu(III) ions in solution was investigated at 77 K in Ir(III)/Eu(III) dyads. Photophysical experiment results show the bridging ligands play an important role in the ET process. Only when the triplet energy level of the bridging ligand was lower than the triplet metal-to-ligand charge transfer ((3)MLCT) energy level of the Ir moiety, was pure emission from the Eu(III) ion observed, implying complete ET took place from the Ir moiety to the Eu(III) ion. PMID:21931913

  2. Rovibrational energy levels of hydrogen peroxide, studied by MULTIMODE with a reaction path Hamiltonian.

    PubMed

    Carter, S; Handy, N C

    2004-07-01

    Recently, Carter and Handy [J. Chem. Phys. 113 (2000) 987] have introduced the theory of the reaction path Hamiltonian (RPH) [J. Chem. Phys. 72 (1980) 99] into the variational scheme MULTIMODE, for the calculation of the J=0 vibrational levels of polyatomic molecules, which have a single large-amplitude motion. In this theory the reaction path coordinate s becomes the fourth dimension of the moment-of-inertia tensor, and must be treated separately from the remaining 3N-7 normal coordinates in the MULTIMODE program. In the modified program, complete integration is performed over s, and the M-mode MULTIMODE coupling approximation for the evaluation of the matrix elements applies only to the 3N-7 normal coordinates. In this paper the new algorithm is extended to the calculation of rotational-vibration energy levels (i.e. J>0) with the RPH, following from our analogous implementation for rigid molecules [Theoret. Chem. Acc. 100 (1998) 191]. The full theory is given, and all extra terms have been included to give the exact kinetic energy operator. In order to validate the new code, we report studies on hydrogen peroxide (H2O2), where the reaction path is equivalent to torsional motion. H2O2 has previously been studied variationally using a valence coordinate Hamiltonian; complete agreement for calculated rovibrational levels is obtained between the previous results and those from the new code, using the identical potential surface. MULTIMODE is now able to calculate rovibrational levels for polyatomic molecules which have one large-amplitude motion. PMID:15248993

  3. Energy levels, radiative rates and electron impact excitation rates for transitions in Si II

    NASA Astrophysics Data System (ADS)

    Aggarwal, Kanti M.; Keenan, Francis P.

    2014-07-01

    Energies for the lowest 56 levels, belonging to the 3s2 3p, 3s 3p2, 3p3, 3s2 3d, 3s 3p 3d, 3s2 4ℓ and 3s2 5ℓ configurations of Si II, are calculated using the General-purpose Relativistic Atomic Structure Package (GRASP) code. Analogous calculations have also been performed (for up to 175 levels) using the Flexible Atomic Code (FAC). Furthermore, radiative rates are calculated for all E1, E2, M1 and M2 transitions. Extensive comparisons are made with available theoretical and experimental energy levels, and the accuracy of the present results is assessed to be better than 0.1 Ryd. Similarly, the accuracy for radiative rates (and subsequently lifetimes) is estimated to be better than 20 per cent for most of the (strong) transitions. Electron impact excitation collision strengths are also calculated, with the Dirac Atomic R-matrix Code (DARC), over a wide energy range up to 13 Ryd. Finally, to determine effective collision strengths, resonances are resolved in a fine energy mesh in the thresholds region. These collision strengths are averaged over a Maxwellian velocity distribution and results listed over a wide range of temperatures, up to 105.5 K. Our data are compared with earlier R-matrix calculations and differences noted, up to a factor of 2, for several transitions. Although scope remains for improvement, the accuracy for our results of collision strengths and effective collision strengths is assessed to be about 20 per cent for a majority of transitions.

  4. Energy transfer and energy level decay processes in Tm{sup 3+}-doped tellurite glass

    SciTech Connect

    Gomes, Laercio; Lousteau, Joris; Milanese, Daniel; Scarpignato, Gerardo C.; Jackson, Stuart D.

    2012-03-15

    The primary excited state decay and energy transfer processes in singly Tm{sup 3+}-doped TeO{sub 2}:ZnO:Bi{sub 2}O{sub 3}:GeO{sub 2} (TZBG) glass relating to the {sup 3}F{sub 4}{yields}{sup 3}H{sub 6}{approx}1.85 {mu}m laser transition have been investigated in detail using time-resolved fluorescence spectroscopy. Selective laser excitation of the {sup 3}H{sub 4} manifold at 794 nm, the {sup 3}H{sub 5} manifold at 1220 nm, and {sup 3}F{sub 4} manifold at 1760 nm has established that the {sup 3}H{sub 5} manifold is entirely quenched by multiphonon relaxation in tellurite glass. The luminescence from the {sup 3}H{sub 4} manifold with an emission peak at 1465 nm suffers strong suppression due to cross relaxation that populates the {sup 3}F{sub 4} level with a near quadratic dependence on the Tm{sup 3+} concentration. The {sup 3}F{sub 4} lifetime becomes longer as the Tm{sup 3+} concentration increases due to energy migration and decreases to 2.92 ms when [Tm{sup 3+}] = 4 mol. % as a result of quasi-resonant energy transfer to free OH{sup -} radicals present in the glass at concentrations between 1 x 10{sup 18} cm{sup -3} and 2 x 10{sup 18} cm{sup -3}. Judd-Ofelt theory in conjunction with absorption measurements were used to obtain the radiative lifetimes and branching ratios of the energy levels located below 25 000 cm{sup -1}. The spectroscopic parameters, the cross relaxation and Tm{sup 3+}({sup 3}F{sub 4}) {yields} OH{sup -} energy transfer rates were used in a numerical model for laser transitions emitting at 2335 nm and 1865 nm.

  5. Relativistic Electron Acceleration during High Intensity Auroral Activities: Maximum Energy Level Dependence

    NASA Astrophysics Data System (ADS)

    Hajra, Rajkumar; Tsurutani, Bruce; Echer, Ezequiel; Gonzalez, Walter

    2015-04-01

    Radiation belt relativistic (E > 0.6, > 2.0, and > 4.0 MeV) electron acceleration at geosynchronous orbit is studied for solar cycle 23 (1995-2008). High-intensity, long-duration, continuous AE activity (HILDCAA) events are considered as the basis of the analyses. Cluster-4 passes were examined for electromagnetic chorus waves in the 5 < L < 10 and 0 < MLT < 12 region. All the HILDCAA events under study were found to be characterized by enhanced whistler-mode chorus waves and flux enhancements of magnetospheric relativistic electrons of all three energies compared to the pre-event flux levels. The response of the energetic electrons to HILDCAAs was found to vary with solar cycle phase. The initial electron fluxes were lower for events occurring during the ascending and solar maximum (AMAX) phases than for events occurring during the descending and solar minimum (DMIN) phases. The flux increases for the DMIN-phase events were > 50% larger than for the AMAX-phase events. It is concluded that electrons are accelerated to relativistic energies most often and most efficiently during the DMIN-phases of the solar cycle. We propose two possible solar UV-related mechanisms to explain this solar cycle effect. Enhanced E > 0.6 MeV electron fluxes at geosynchronous orbit were first detected ~1 day after the statistical onset of HILDCAAs, E > 2.0 MeV electrons after ~1.5 days, and E > 4.0 MeV electrons after ~2.5 days. We estimated acceleration and decay rates and timescales for the three energy levels, which will be provided for wave-particle investigators to attempt to match their models to empirically derived values.

  6. Optimal Monochromatic Energy Levels in Spectral CT Pulmonary Angiography for the Evaluation of Pulmonary Embolism

    PubMed Central

    Wu, Huawei; Zhang, Qing; Hua, Jia; Hua, Xiaolan; Xu, Jianrong

    2013-01-01

    Background The aim of this study was to determine the optimal monochromatic spectral CT pulmonary angiography (sCTPA) levels to obtain the highest image quality and diagnostic confidence for pulmonary embolism detection. Methods The Institutional Review Board of the Shanghai Jiao Tong University School of Medicine approved this study, and written informed consent was obtained from all participating patients. Seventy-two patients with pulmonary embolism were scanned with spectral CT mode in the arterial phase. One hundred and one sets of virtual monochromatic spectral (VMS) images were generated ranging from 40 keV to 140 keV. Image noise, clot diameter and clot to artery contrast-to-noise ratio (CNR) from seven sets of VMS images at selected monochromatic levels in sCTPA were measured and compared. Subjective image quality and diagnostic confidence for these images were also assessed and compared. Data were analyzed by paired t test and Wilcoxon rank sum test. Results The lowest noise and the highest image quality score for the VMS images were obtained at 65 keV. The VMS images at 65 keV also had the second highest CNR value behind that of 50 keV VMS images. There was no difference in the mean noise and CNR between the 65 keV and 70 keV VMS images. The apparent clot diameter correlated with the keV levels. Conclusions The optimal energy level for detecting pulmonary embolism using dual-energy spectral CT pulmonary angiography was 65–70 keV. Virtual monochromatic spectral images at approximately 65–70 keV yielded the lowest image noise, high CNR and highest diagnostic confidence for the detection of pulmonary embolism. PMID:23667583

  7. Energy level alignment in polymer organic solar cells at donor-acceptor planar junction formed by electrospray vacuum deposition

    SciTech Connect

    Kim, Ji-Hoon; Hong, Jong-Am; Kwon, Dae-Gyeon; Seo, Jaewon; Park, Yongsup

    2014-04-21

    Using ultraviolet photoelectron spectroscopy (UPS), we have measured the energy level offset at the planar interface between poly(3-hexylthiophene) (P3HT) and C{sub 61}-butyric acid methylester (PCBM). Gradual deposition of PCBM onto spin-coated P3HT in high vacuum was made possible by using electrospray vacuum deposition (EVD). The UPS measurement of EVD-prepared planar interface resulted in the energy level offset of 0.91 eV between P3HT HOMO and PCBM LUMO, which is considered as the upper limit of V{sub oc} of the organic photovoltaic cells.

  8. Energy levels and zero field splitting parameter for Fe{sup 2+} doped in ZnS

    SciTech Connect

    Ivaşcu, Simona

    2013-11-13

    The aim of present paper is to report the results on the modeling of the crystal field parameters of Fe{sup 2+} doped in host matrix ZnS, simulate the energy levels scheme and calculate the zero field splitting parameter D of such system. The crystal field parameters were modeled in the frame of the superposition model of crystal field and the simulation of the energy levels scheme and calculation of the zero field splitting parameters done by diagonalization the Hamiltonian of Fe{sup 2+}:ZnS system. The obtained results were disscused and compared with experimental data. Satisfactory agreement have been obtained.

  9. Effect of residual gases in high vacuum on the energy-level alignment at noble metal/organic interfaces

    SciTech Connect

    Helander, M. G.; Wang, Z. B.; Lu, Z. H.

    2011-10-31

    The energy-level alignment at metal/organic interfaces has traditionally been studied using ultraviolet photoelectron spectroscopy (UPS) in ultra-high vacuum (UHV). However, since most devices are fabricated in high vacuum (HV), these studies do not accurately reflect the interfaces in real devices. We demonstrate, using UPS measurements of samples prepared in HV and UHV and current-voltage measurements of devices prepared in HV, that the small amounts of residual gases that are adsorbed on the surface of clean Cu, Ag, and Au (i.e., the noble metals) in HV can significantly alter the energy-level alignment at metal/organic interfaces.

  10. Electron-phonon interaction effect on the energy levels and diamagnetic susceptibility of quantum wires: Parallelogram and triangle cross section

    SciTech Connect

    Khordad, R. Bahramiyan, H.

    2014-03-28

    In this paper, optical phonon modes are studied within the framework of dielectric continuum approach for parallelogram and triangular quantum wires, including the derivation of the electron-phonon interaction Hamiltonian and a discussion on the effects of this interaction on the electronic energy levels. The polaronic energy shift is calculated for both ground-state and excited-state electron energy levels by applying the perturbative approach. The effects of the electron-phonon interaction on the expectation value of r{sup 2} and diamagnetic susceptibility for both quantum wires are discussed.

  11. The energy-level crossing behavior and quantum Fisher information in a quantum well with spin-orbit coupling

    PubMed Central

    Wang, Z. H.; Zheng, Q.; Wang, Xiaoguang; Li, Yong

    2016-01-01

    We study the energy-level crossing behavior in a two-dimensional quantum well with the Rashba and Dresselhaus spin-orbit couplings (SOCs). By mapping the SOC Hamiltonian onto an anisotropic Rabi model, we obtain the approximate ground state and its quantum Fisher information (QFI) via performing a unitary transformation. We find that the energy-level crossing can occur in the quantum well system within the available parameters rather than in cavity and circuit quantum eletrodynamics systems. Furthermore, the influence of two kinds of SOCs on the QFI is investigated and an intuitive explanation from the viewpoint of the stationary perturbation theory is given. PMID:26931762

  12. A Critical Compilation of Energy Levels, Spectral Lines, and Transition Probabilities of Singly Ionized Silver, Ag II

    PubMed Central

    Kramida, Alexander

    2013-01-01

    All available experimental measurements of the spectrum of the Ag+ ion are critically reviewed. Systematic shifts are removed from the measured wavelengths. The compiled list of critically evaluated wavelengths is used to derive a comprehensive list of energy levels with well-defined uncertainties. Eigenvector compositions and level designations are found in two alternate coupling schemes. Some of the older work is found to be incorrect. A revised value of the ionization energy, 173283(7) cm−1, equivalent to 21.4844(8) eV, is derived from the new energy levels. A set of critically evaluated transition probabilities is given. PMID:26401429

  13. Low Bone Density

    MedlinePlus

    ... Density Exam/Testing › Low Bone Density Low Bone Density Low bone density is when your bone density ... people with normal bone density. Detecting Low Bone Density A bone density test will determine whether you ...

  14. Effect of diet energy level and genomic residual feed intake on dairy heifer performance

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The objective of this study was to determine the growth, feed intake, and feed efficiency of dairy heifers with different genomically predicted residual feed intakes (RFI), and offered diets differing in energy density. Post-bred Holstein heifers (N=128; ages 14-20 months) were blocked by initial we...

  15. Analytical Calculation of Energy levels of mono- and bilayer Graphene Quantum Dots Used as Light Absorber in Solar Cells

    NASA Astrophysics Data System (ADS)

    Tamandani, Shahryar; Darvish, Ghafar; Faez, Rahim

    2016-01-01

    In this paper by solving Dirac equation, we present an analytical solution to calculate energy levels and wave functions of mono- and bilayer graphene quantum dots. By supposing circular quantum dots, we solve Dirac equation and obtain energy levels and band gap with relations in a new closed and practical form. The energy levels are correlated with a radial quantum number and radius of quantum dots. In addition to monolayer quantum dots, AA- and AB-stacked bilayer quantum dots are investigated and their energy levels and band gap are calculated as well. Also, we analyze the influence of the quantum dots size on their energy spectrum. It can be observed that the band gap decreases as quantum dots' radius increases. On the other hand, increase in the band gap is more in AB-stacked bilayer quantum dots. Using the obtained relations, the band gap is obtained in each state. Comparing the energy spectra obtained from the tight-binding approximation with those of our obtained relations shows that the behavior of the energies as function of the dot size is qualitatively similar, but in some cases, quantitative differences can be seen. As quantum dots radius increases, the analytical results approach to the tight-binding method results.

  16. Fine-structure calculations of energy levels, oscillator strengths, and transition probabilities for sulfur-like iron, Fe XI

    NASA Astrophysics Data System (ADS)

    Abou El-Maaref, A.; Ahmad, Mahmoud; Allam, S. H.

    2014-05-01

    Energy levels, oscillator strengths, and transition probabilities for transitions among the 14 LS states belonging to configurations of sulfur-like iron, Fe XI, have been calculated. These states are represented by configuration interaction wavefunctions and have configurations 3s23p4, 3s3p5, 3s23p33d, 3s23p34s, 3s23p34p, and 3s23p34d, which give rise to 123 fine-structure energy levels. Extensive configuration interaction calculations using the CIV3 code have been performed. To assess the importance of relativistic effects, the intermediate coupling scheme by means of the Breit-Pauli Hamiltonian terms, such as the one-body mass correction and Darwin term, and spin-orbit, spin-other-orbit, and spin-spin corrections, are incorporated within the code. These incorporations adjusted the energy levels, therefore the calculated values are close to the available experimental data. Comparisons between the present calculated energy levels as well as oscillator strengths and both experimental and theoretical data have been performed. Our results show good agreement with earlier works, and they might be useful in thermonuclear fusion research and astrophysical applications.

  17. Response of chicks to two diets of differing energy levels under conditions of brooding with or without supplemental heat

    NASA Astrophysics Data System (ADS)

    Donkoh, A.; Kese, A. G.

    1987-12-01

    A 2×2 factorial experiment was conducted to determine the performance and certain physiological parameters of 200 day-old chicks fed diets containing either 2600 or 3000 kcal metabolizable energy (ME) per kilogram for a period of 28 days under conditions of brooding with or without supplemental heat in a hot humid tropical area. The results indicated that within each dietary energy level, there was no significant difference in growth rates of chicks brooded with or without supplemental heat, however, the high energy diet significantly (P<0.01) promoted greater weight gains than the low energy diet. Brooding chicks with supplemental heat and with the high energy diet, decreased feed intake and improved feed conversion efficiency. Chicks brooded without supplemental heat consumed significantly (P<0.01) less water than those brooded with heat, irrespective of the dietary energy level. Mortality and blood glucose levels were not affected by the heat and dietary energy treatments. Thyroid weight expressed as percentage of body weight, haemoglobin and hematocrit values were significantly (P<0.01) higher for chicks brooded without supplemental heat. On the other hand, dietary energy levels did not exert any effect on these physiological parameters. No significant heat and dietary energy level interaction effects were noted on all the parameters considered under this trial.

  18. Simultaneous integrated boost to intraprostatic lesions using different energy levels of intensity-modulated radiotherapy and volumetric-arc therapy

    PubMed Central

    Sonmez, S; Erbay, G; Guler, O C; Arslan, G

    2014-01-01

    Objective: This study compared the dosimetry of volumetric-arc therapy (VMAT) and intensity-modulated radiotherapy (IMRT) with a dynamic multileaf collimator using the Monte Carlo algorithm in the treatment of prostate cancer with and without simultaneous integrated boost (SIB) at different energy levels. Methods: The data of 15 biopsy-proven prostate cancer patients were evaluated. The prescribed dose was 78 Gy to the planning target volume (PTV78) including the prostate and seminal vesicles and 86 Gy (PTV86) in 39 fractions to the intraprostatic lesion, which was delineated by MRI or MR-spectroscopy. Results: PTV dose homogeneity was better for IMRT than VMAT at all energy levels for both PTV78 and PTV86. Lower rectum doses (V30–V50) were significantly higher with SIB compared with PTV78 plans in both IMRT and VMAT plans at all energy levels. The bladder doses at high dose level (V60–V80) were significantly higher in IMRT plans with SIB at all energy levels compared with PTV78 plans, but no significant difference was observed in VMAT plans. VMAT plans resulted in a significant decrease in the mean monitor units (MUs) for 6, 10, and 15 MV energy levels both in plans with and those without SIB. Conclusion: Dose escalation to intraprostatic lesions with 86 Gy is safe without causing serious increase in organs at risk (OARs) doses. VMAT is advantageous in sparing OARs and requiring less MU than IMRT. Advances in knowledge: VMAT with SIB to intraprostatic lesion is a feasible method in treating prostate cancer. Additionally, no dosimetric advantage of higher energy is observed. PMID:24319009

  19. Fine-structure calculations of energy levels, oscillator strengths, and transition probabilities for sulfur-like iron, Fe XI

    SciTech Connect

    Abou El-Maaref, A.; Ahmad, Mahmoud; Allam, S.H.

    2014-05-15

    Energy levels, oscillator strengths, and transition probabilities for transitions among the 14 LS states belonging to configurations of sulfur-like iron, Fe XI, have been calculated. These states are represented by configuration interaction wavefunctions and have configurations 3s{sup 2}3p{sup 4}, 3s3p{sup 5}, 3s{sup 2}3p{sup 3}3d, 3s{sup 2}3p{sup 3}4s, 3s{sup 2}3p{sup 3}4p, and 3s{sup 2}3p{sup 3}4d, which give rise to 123 fine-structure energy levels. Extensive configuration interaction calculations using the CIV3 code have been performed. To assess the importance of relativistic effects, the intermediate coupling scheme by means of the Breit–Pauli Hamiltonian terms, such as the one-body mass correction and Darwin term, and spin–orbit, spin–other-orbit, and spin–spin corrections, are incorporated within the code. These incorporations adjusted the energy levels, therefore the calculated values are close to the available experimental data. Comparisons between the present calculated energy levels as well as oscillator strengths and both experimental and theoretical data have been performed. Our results show good agreement with earlier works, and they might be useful in thermonuclear fusion research and astrophysical applications. -- Highlights: •Accurate atomic data of iron ions are needed for identification of solar corona. •Extensive configuration interaction wavefunctions including 123 fine-structure levels have been calculated. •The relativistic effects by means of the Breit–Pauli Hamiltonian terms are incorporated. •This incorporation adjusts the energy levels, therefore the calculated values are close to experimental values.

  20. Investigation of possible correlation between α -particle preformation probability and energy levels for α emitters with 74 ≤Z ≤83

    NASA Astrophysics Data System (ADS)

    Ismail, M.; Adel, A.

    2014-12-01

    The preformation probability of an α cluster inside radioactive parent nuclei is investigated. The calculations are employed in the framework of the density-dependent cluster model for both even-even and odd-A isotopes with 74 ≤Z ≤83 . A realistic density-dependent nucleon-nucleon (N N ) interaction with a finite-range exchange part is used to calculate the microscopic α -nucleus potential in the well-established double-folding model. The main effect of antisymmetrization under exchange of nucleons between the α and daughter nuclei has been included in the folding model through the finite-range exchange part of the N N interaction. The calculated potential is then implemented to find both the assault frequency and the penetration probability of the α particle by means of the Wentzel-Kramers-Brillouin approximation in combination with the Bohr-Sommerfeld quantization condition. We investigated the correlation between the α -particle preformation probability, Sα, and the energy levels of the parent nucleus for α emitters with atomic number 74 ≤Z ≤83 . Based on the similarity in the behavior of Sα with the neutron number for two nuclei, we try to predict or confirm the unknown or doubted nuclear spins and parities in this mass region.

  1. Optical probing of MgZnO/ZnO heterointerface confinement potential energy levels

    SciTech Connect

    Solovyev, V. V.; Van'kov, A. B.; Kukushkin, I. V.; Falson, J.; Kozuka, Y.; Zhang, D.; Smet, J. H.; Maryenko, D.; Tsukazaki, A.; Kawasaki, M.

    2015-02-23

    Low-temperature photoluminescence and reflectance measurements were employed to study the optical transitions present in two-dimensional electron systems confined at Mg{sub x}Zn{sub 1–x}O/ZnO heterojunctions. Transitions involving A- and B-holes and electrons from the two lowest subbands formed within the confinement potential are detected. In the studied density range of 2.0–6.5 × 10{sup 11 }cm{sup −2}, the inter-subband splitting is measured and the first excited electron subband is shown to be empty of electrons.

  2. Probing hybridization of a single energy level coupled to superconducting leads

    NASA Astrophysics Data System (ADS)

    van Zanten, D. M. T.; Balestro, F.; Courtois, H.; Winkelmann, C. B.

    2015-11-01

    Electron transport through a quantum dot coupled to superconducting leads shows a sharp conductance onset when a quantum dot orbital level crosses the superconducting coherence peak of one lead. We study superconducting single electron transistors in the weak coupling limit by connecting individual gold nanoparticles with aluminum leads formed by electromigration. We show that the transport features close to the conductance onset threshold can be accurately described by the quantum dot levels' hybridization with the leads, which is strongly enhanced by the divergent density of states at the superconducting gap edge. This highlights the importance of electron cotunneling effects in spectroscopies with superconducting probes.

  3. The self-consistent calculation of pseudo-molecule energy levels, construction of energy level correlation diagrams and an automated computation system for SCF-X(Alpha)-SW calculations

    NASA Technical Reports Server (NTRS)

    Schlosser, H.

    1981-01-01

    The self consistent calculation of the electronic energy levels of noble gas pseudomolecules formed when a metal surface is bombarded by noble gas ions is discussed along with the construction of energy level correlation diagrams as a function of interatomic spacing. The self consistent field x alpha scattered wave (SCF-Xalpha-SW) method is utilized. Preliminary results on the Ne-Mg system are given. An interactive x alpha programming system, implemented on the LeRC IBM 370 computer, is described in detail. This automated system makes use of special PROCDEFS (procedure definitions) to minimize the data to be entered manually at a remote terminal. Listings of the special PROCDEFS and of typical input data are given.

  4. Interplay between Self-Assembled Structures and Energy Level Alignment of Benzenediamine on Au(111) Surfaces

    NASA Astrophysics Data System (ADS)

    Li, Guo; Neaton, Jeffrey

    2015-03-01

    Using van der Waals-corrected density functional theory (DFT) calculations, we study the adsorption of benzene-diamine (BDA) molecules on Au(111) surfaces. We find that at low surface coverage, the adsorbed molecules prefer to stay isolated from each other in a monomer phase, due to the inter-molecular dipole-dipole repulsions. However, when the coverage rises above a critical value of 0.9nm-2, the adsorbed molecules aggregate into linear structures via hydrogen bonding between amine groups, consistent with recent experiments [Haxton, Zhou, Tamblyn, et al, Phys. Rev. Lett. 111, 265701 (2013)]. Moreover, we find that these linear structures at high density considerably reduces the Au work function (relative to a monomer phase). Due to reduced surface polarization effects, we estimate that the resonance energy of the highest occupied molecular orbital of the adsorbed BDA molecule relative to the Au Fermi level is significantly lower than the monomer phase by more than 0.5 eV, consistent with the experimental measurements [DellAngela, Kladnik, and Cossaro, et al., Nano Lett. 10, 2470 (2010)]. This work supported by DOE (the JCAP under Award Number DE-SC000499 and the Molecular Foundry of LBNL), and computational resources provided by NERSC.

  5. FORBIDDEN AND INTERCOMBINATION LINES OF RR TELESCOPII: WAVELENGTH MEASUREMENTS AND ENERGY LEVELS

    SciTech Connect

    Young, P. R.; Feldman, U.; Lobel, A.

    2011-10-01

    Ultraviolet and visible spectra of the symbiotic nova RR Telescopii are used to derive reference wavelengths for many forbidden and intercombination transitions of ions +1 to +6 of elements C, N, O, Ne, Na, Mg, Al, Si, P, S, Cl, Ar, K, and Ca. The wavelengths are then used to determine new energy values for the levels within the ions' ground configurations or first excited configuration. The spectra were recorded by the Space Telescope Imaging Spectrograph of the Hubble Space Telescope and the Ultraviolet Echelle Spectrograph of the European Southern Observatory in 2000 and 1999, respectively, and cover 1140-6915 A. Particular care was taken to assess the accuracy of the wavelength scale between the two instruments. An investigation of the profiles of the emission lines reveals that the nebula consists of at least two plasma components at different velocities. The components have different densities, and a simple model of the lines' emissions demonstrates that most of the lines principally arise from the high density component. Only these lines were used for the wavelength study.

  6. Interfacial energy level alignments between low-band-gap polymer PTB7 and indium zinc oxide anode

    NASA Astrophysics Data System (ADS)

    Shin, Dongguen; Lee, Jeihyun; Park, Soohyung; Jeong, Junkyeong; Seo, Ki-Won; Kim, Hyo-Joong; Kim, Han-Ki; Choi, Min-Jun; Chung, Kwun-Bum; Yi, Yeonjin

    2015-09-01

    The interfacial energy level alignments between poly(thieno[3,4-b]-thiophene)-co-benzodithiophene (PTB7) and indium zinc oxide (IZO) were investigated. In situ ultraviolet photoemission spectroscopy measurements were conducted with the step-by-step deposition of PTB7 on IZO substrate. All spectral changes were analyzed between each deposition step, and interfacial energy level alignments were estimated. The hole barrier of standard ultraviolet-ozone treated IZO is 0.58 eV, which is lower than the value of 1.09 eV obtained for bare IZO. The effect of barrier reduction on the hole transport was also confirmed with electrical measurements of hole-dominated devices.

  7. Effect of dt{mu} quasinucleus structure on energy levels of the (dt{mu})Xee exotic molecule

    SciTech Connect

    Kartavtsev, O.I.; Malykh, A.V.; Permyakov, V.P.

    2004-08-01

    Precise energies of rovibrational states of the exotic hydrogen-like molecule (dt{mu})Xee are of importance for dt{mu} resonant formation, which is a key process in the muon-catalyzed fusion cycle. The effect of the internal structure and rotation of the dt{mu} quasi-nucleus on energy levels is studied using the three-body description of the (dt{mu})Xee molecule based on the hierarchy of scales and corresponding energies of its constituent subsystems. For a number of rovibrational states of (dt{mu})dee and (dt{mu})tee, the shifts and splittings of energy levels are calculated in the second order of the perturbation theory.

  8. Nuclear level density: Shell-model approach

    NASA Astrophysics Data System (ADS)

    Sen'kov, Roman; Zelevinsky, Vladimir

    2016-06-01

    Knowledge of the nuclear level density is necessary for understanding various reactions, including those in the stellar environment. Usually the combinatorics of a Fermi gas plus pairing is used for finding the level density. Recently a practical algorithm avoiding diagonalization of huge matrices was developed for calculating the density of many-body nuclear energy levels with certain quantum numbers for a full shell-model Hamiltonian. The underlying physics is that of quantum chaos and intrinsic thermalization in a closed system of interacting particles. We briefly explain this algorithm and, when possible, demonstrate the agreement of the results with those derived from exact diagonalization. The resulting level density is much smoother than that coming from conventional mean-field combinatorics. We study the role of various components of residual interactions in the process of thermalization, stressing the influence of incoherent collision-like processes. The shell-model results for the traditionally used parameters are also compared with standard phenomenological approaches.

  9. Correlation between the energy level structure of cerium-doped yttrium aluminum garnet and luminescent behavior at varying temperatures

    NASA Astrophysics Data System (ADS)

    Song, Zhen; Liu, Xiaolang; He, Lizhu; Liu, Q. L.

    2016-05-01

    Luminescent spectra of cerium-doped yttrium aluminum garnet are measured at varying temperatures. It is found that the two excitation peaks demonstrate a reverse trend as the temperature rises, and the breadth of the high-energy emission peak experiences an abrupt widening. These effects could be directly linked to the energy level scheme of Ce3+ under the crystal field of local symmetry. Moreover, an alternative fitting function is provided which could effectively resolve the emission curve.

  10. Ab initio potential energy surface and vibration-rotation energy levels of silicon dicarbide, SiC2.

    PubMed

    Koput, Jacek

    2016-10-01

    The accurate ground-state potential energy surface of silicon dicarbide, SiC2 , has been determined from ab initio calculations using the coupled-cluster approach. Results obtained with the conventional and explicitly correlated coupled-cluster methods were compared. The core-electron correlation, higher-order valence-electron correlation, and scalar relativistic effects were taken into account. The potential energy barrier to the linear SiCC configuration was predicted to be 1782 cm(-1) . The vibration-rotation energy levels of the SiC2 , (29) SiC2 , (30) SiC2 , and SiC(13) C isotopologues were calculated using a variational method. The experimental vibration-rotation energy levels of the main isotopologue were reproduced to high accuracy. In particular, the experimental energy levels of the highly anharmonic vibrational ν3 mode of SiC2 were reproduced to within 6.7 cm(-1) , up to as high as the v3  = 16 state. PMID:27481562

  11. Position-dependent energy-level shifts of an accelerated atom in the presence of a boundary

    SciTech Connect

    Zhu Zhiying; Yu Hongwei

    2010-10-15

    We consider a uniformly accelerated atom interacting with a vacuum electromagnetic field in the presence of an infinite conducting plane boundary and calculate separately the contributions of vacuum fluctuations and radiation reaction to the atomic energy-level shift. We analyze in detail the behavior of the total energy shift in three different regimes of the distance in both the low-acceleration and high-acceleration limits. Our results show that, in general, an accelerated atom does not behave as if immersed in a thermal bath at the Unruh temperature in terms of the atomic energy-level shifts, and the effect of the acceleration on the atomic energy-level shifts may in principle become appreciable in certain circumstances, although it may not be realistic for actual experimental measurements. We also examine the effects of the acceleration on the level shifts when the acceleration is of the order of the transition frequency of the atom and we find some features which differ from what was obtained in the existing literature.

  12. Probing the energy levels of perovskite solar cells via Kelvin probe and UV ambient pressure photoemission spectroscopy.

    PubMed

    Harwell, J R; Baikie, T K; Baikie, I D; Payne, J L; Ni, C; Irvine, J T S; Turnbull, G A; Samuel, I D W

    2016-07-20

    The field of organo-lead halide perovskite solar cells has been rapidly growing since their discovery in 2009. State of the art devices are now achieving efficiencies comparable to much older technologies like silicon, while utilising simple manufacturing processes and starting materials. A key parameter to consider when optimising solar cell devices or when designing new materials is the position and effects of the energy levels in the materials. We present here a comprehensive study of the energy levels present in a common structure of perovskite solar cell using an advanced macroscopic Kelvin probe and UV air photoemission setup. By constructing a detailed map of the energy levels in the system we are able to predict the importance of each layer to the open circuit voltage of the solar cell, which we then back up through measurements of the surface photovoltage of the cell under white illumination. Our results demonstrate the effectiveness of air photoemission and Kelvin probe contact potential difference measurements as a method of identifying the factors contributing to the open circuit voltage in a solar cell, as well as being an excellent way of probing the physics of new materials. PMID:27384817

  13. Energy levels, oscillator strengths, and radiative rates for Si-like Zn XVII, Ga XVIII, Ge XIX, and As XX

    SciTech Connect

    Abou El-Maaref, A.; Allam, S.H.; El-Sherbini, Th.M.

    2014-01-15

    The energy levels, oscillator strengths, line strengths, and transition probabilities for transitions among the terms belonging to the 3s{sup 2}3p{sup 2}, 3s3p{sup 3}, 3s{sup 2}3p3d, 3s{sup 2}3p4s, 3s{sup 2}3p4p and 3s{sup 2}3p4d configurations of silicon-like ions (Zn XVII, Ga XVIII, Ge XIX, and As XX) have been calculated using the configuration-interaction code CIV3. The calculations have been carried out in the intermediate coupling scheme using the Breit–Pauli Hamiltonian. The present calculations have been compared with the available experimental data and other theoretical calculations. Most of our calculations of energy levels and oscillator strengths (in length form) show good agreement with both experimental and theoretical data. Lifetimes of the excited levels have also been calculated. -- Highlights: •We have calculated the fine-structure energy levels of Si-like Zn, Ga, Ge and As. •The calculations are performed using the configuration interaction method (CIV3). •We have calculated the oscillator strengths, line strengths and transition rates. •The wavelengths of the transitions are listed in this article. •We also have made comparisons between our data and other calculations.

  14. Interface-Induced Renormalization of Electrolyte Energy Levels in Magnesium Batteries.

    PubMed

    Kumar, Nitin; Siegel, Donald J

    2016-03-01

    A promising strategy for increasing the energy density of Li-ion batteries is to substitute a multivalent (MV) metal for the commonly used lithiated carbon anode. Magnesium is a prime candidate for such a MV battery due to its high volumetric capacity, abundance, and limited tendency to form dendrites. One challenge that is slowing the implementation of Mg-based batteries, however, is the development of efficient and stable electrolytes. Computational screening for molecular species having sufficiently wide electrochemical windows is a starting point for the identification of optimal electrolytes. Nevertheless, this window can be altered via interfacial interactions with electrodes. These interactions are typically omitted in screening studies, yet they have the potential to generate large shifts to the HOMO and LUMO of the electrolyte components. The present study quantifies the stability of several common electrolyte solvents on model electrodes of relevance for Mg batteries. Many-body perturbation theory calculations based on the G0W0 method were used to predict shifts in a solvent's electronic levels arising from interfacial interactions. In molecules exhibiting large dipole moments, our calculations indicate that these interactions reduce the HOMO-LUMO gap by ∼25% (compared to isolated molecules). We conclude that electrode interactions can narrow an electrolyte's electrochemical window significantly, thereby accelerating redox decomposition reactions. Accounting for these interactions in screening studies presents an opportunity to refine predictions of electrolyte stability. PMID:26888224

  15. Optimization of the Energy Level Alignment between the Photoactive Layer and the Cathode Contact Utilizing Solution-Processed Hafnium Acetylacetonate as Buffer Layer for Efficient Polymer Solar Cells.

    PubMed

    Yu, Lu; Li, Qiuxiang; Shi, Zhenzhen; Liu, Hao; Wang, Yaping; Wang, Fuzhi; Zhang, Bing; Dai, Songyuan; Lin, Jun; Tan, Zhan'ao

    2016-01-13

    The insertion of an appropriate interfacial buffer layer between the photoactive layer and the contact electrodes makes a great impact on the performance of polymer solar cells (PSCs). Ideal interfacial buffer layers could minimize the interfacial traps and the interfacial barriers caused by the incompatibility between the photoactive layer and the electrodes. In this work, we utilized solution-processed hafnium(IV) acetylacetonate (Hf(acac)4) as an effective cathode buffer layer (CBL) in PSCs to optimize the energy level alignment between the photoactive layer and the cathode contact, with the short-circuit current density (Jsc), open-circuit voltage (Voc), and fill factor (FF) all simultaneously improved with Hf(acac)4 CBL, leading to enhanced power conversion efficiencies (PCEs). Ultraviolet photoemission spectroscopy (UPS) and scanning Kelvin probe microscopy (SKPM) were performed to confirm that the interfacial dipoles were formed with the same orientation direction as the built-in potential between the photoactive layer and Hf(acac)4 CBL, benefiting the exciton separation and electron transport/extraction. In addition, the optical characteristics and surface morphology of the Hf(acac)4 CBL were also investigated. PMID:26684416

  16. Structure and energy level alignment at the dye-electrode interface in p-type DSSCs: new hints on the role of anchoring modes from ab initio calculations.

    PubMed

    Muñoz-García, Ana B; Pavone, Michele

    2015-05-14

    p-type dye-sensitized solar cells (DSSCs) represent the complementary photocathodes to the well-studied n-type DSSCs (Grätzel cells), but their low performances have hindered the development of convenient tandem solar cells based on cost-effective n- and p-type DSSCs. Because of their low efficiencies, experimental investigations highlighted the role of hole-electron transport processes at the dye-electrode interface. However, the effects of the dye anchoring groups on interfacial electronic features are still unclear. We report here a first principles study of a benchmark p-type DSSC model, namely the widely used Coumarin-based dye C343 adsorbed on the p-NiO surface. Together with the original carboxylic acid, we test the alternative phosphonic acid as the anchoring group. We investigate binding energies, structural features and electronic energy level alignments: our results highlight that these properties are highly sensitive to the binding modes. In particular, both the chemical nature of the anchoring group and the binding mode strongly affect the thermodynamic driving force for the dye-electrode hole injection process. From analysis of the electronic densities, we find that favorable driving forces are correlated with small values of the interfacial electrostatic dipole that is formed upon dye adsorption. From our results, we derive new hints for improving open circuit potential and the hole injection process in p-type DSSCs based on NiO electrodes. PMID:25892559

  17. Orientation dependant charge transfer at fullerene/Zn-phthalocyanine (C60/ZnPc) interface: Implications for energy level alignment and photovoltaic properties

    NASA Astrophysics Data System (ADS)

    Javaid, Saqib; Javed Akhtar, M.

    2016-08-01

    Recently, experimental results have shown that photovoltaic properties of Fullerene (C60)/Phthalocyanine based devices improve considerably as molecular orientation is changed from edge-on to face-on. In this work, we have studied the impact of molecular orientation on C60/ZnPc interfacial properties, particularly focusing on experimentally observed face-on and edge-on configuration, using density functional theory based simulations. The results show that the interfacial electronic properties are strongly anisotropic: direction of charge transfer and interface dipole fluctuates as molecular orientation is switched. As a result of orientation dependant interface dipole, difference between acceptor LUMO and donor HOMO increases as the orientation is changed from edge-on to face-on, suggesting a consequent increase in open circuit voltage (VOC). Moreover, adsorption and electronic properties indicate that the interfacial interactions are much stronger in the face-on configuration which should further facilitate the charge-separation process. These findings elucidate the energy level alignment at C60/ZnPc interface and help to identify interface dipole as the origin of the orientation dependence of VOC.

  18. A new approach to the symmetric rectangular quantum well: Analytic determination of well width from energy levels

    NASA Astrophysics Data System (ADS)

    Fouillant, C.; Alibert, C.

    1994-06-01

    Many articles on the determination of the energy levels of a symmetric rectangular quantum well (SRQW) have been published in this Journal over the past 20 years. Standard textbooks of quantum mechanics as well as research papers offer graphical solutions. Exercises on quantum well (QW) remain rather difficult for students, because transcendental equations must be solved with boundaries at which the solution will be discontinuous. Numerical solutions generally determine the energy (En), assuming that the thickness is known, for each level number n. In this note, we show that the width L of an SRQW can be expressed directly as a function of the energy En for n=0,1,2,3,... .

  19. Positronium energy levels at order m α7 : Product contributions in the two-photon-annihilation channel

    NASA Astrophysics Data System (ADS)

    Adkins, Gregory S.; Tran, Lam M.; Wang, Ruihan

    2016-05-01

    Ongoing improvements in the measurement of positronium transition intervals motivate the calculation of the O (m α7) corrections to these intervals. In this work we focus on corrections to the spin-singlet parapositronium energies involving virtual annihilation to two photons in an intermediate state. We have evaluated all contributions to the positronium S -state energy levels that can be written as the product of a one-loop correction on one side of the annihilation event and another one-loop correction on the other side. These effects contribute Δ E =-0.561971 (25 ) m α7/π3 to the parapositronium ground-state energy.

  20. MULTIPLE THICKNESS TIMES DENSITY GAMMA GAGE

    DOEpatents

    Cherry, N.H.

    1962-07-24

    A device was developed for measuring simultaneously the thicknesses of two dissimilar materials superimposed on each other, such as coating of one material on another. The apparatus utilizes a double gamma radiation source producing radiation in two narrow band energy levels. The different materials attenuate the two bands of energy unequally with the result that a composite signal is received which can be analyzed to separate out the components due to the differing materials and indicate the thickness or densities of the two layers. (AEC)

  1. Interplay between Energy-Level Position and Charging Effect of Manganese Phthalocyanines on an Atomically Thin Insulator.

    PubMed

    Liu, Liwei; Dienel, Thomas; Widmer, Roland; Gröning, Oliver

    2015-10-27

    Understanding the energy-level alignment and charge transfer of organic molecules at large bandgap semiconductors is of crucial importance to optimize device performance in organic electronics. We have studied submonolayer coverage of manganese phthalocyanine (MnPc) on hexagonal boron nitride (h-BN) on Rh(111) as a model system by low-temperature scanning tunneling microscopy (STM) and spectroscopy (STS). The adsorbed molecules show three distinctly different bias-dependent topographic signatures, which depend on their adsorption positions on the h-BN. Among these three types of MnPc, one shows pronounced charging because of the proximity of the highest occupied molecular orbital (HOMO) to the Fermi level on the decoupling h-BN substrate. The charging of the MnPc from its neutral to the MnPc(+) state leads to a down shift of the Mn 3d-related orbital by 840 meV as determined from the difference in energy position between high- and low-bias charging. We find that the charging field is linearly related to the HOMO position with respect to the Fermi level, with a clear correlation to the adsorption orientations of the MnPc. Our results show how critically energy level alignment and field-induced charge transfer process can depend on adsorption configurations, even on an apparently low-interacting substrate like metal supported monolayer h-BN. PMID:26390030

  2. VizieR Online Data Catalog: SiIX K-shell energy levels and transitions (Wei+, 2014)

    NASA Astrophysics Data System (ADS)

    Wei, H. G.; Shi, J. R.; Wang, F. L.; Zhong, J. Y.; Liang, G. Y.; Zhao, G.

    2014-05-01

    Accurate atomic data are needed to analyze the SiIX K-shell features in astrophysical X-ray spectra. Relative large discrepancies in the existing atomic data have impeded this progress. We present the accurate SiIX K-shell transition data, including K-shell energy levels, wavelengths, radiative rates, and oscillator strengths. The flexible atomic code (FAC), which is a fully relativistic atomic code with configuration interaction (CI) included, was employed to calculate these data. To investigate the CI effects, calculations with different configurations included were carried out. The K-shell atomic data of SiIX transitions between 1s22s22p2, 1s22s2p3, 1s22p4, 1s2s22p3, 1s2s2p4, and 1s2p5 are reported. The accuracy of our data is demonstrated by comparing them with the available experimental measurements and theoretical calculations. The energy levels are accurate to 3.5eV, the wavelengths to within 15mÅ. For most transitions, the radiative rates an accuracy of 20%. The effects of CI from high-energy configurations were investigated as well. (2 data files).

  3. Quantum effect on the energy levels of Eu2+ doped K2Ca2(SO4)3 nanoparticles.

    PubMed

    Salah, Numan; Habib, Sami S; Khan, Zishan H

    2010-09-01

    Quantum confinement effect on the energy levels of Eu(2+) doped K(2)Ca(2)(SO(4))(3) nanoparticles has been observed. The broad photoluminescence (PL) emission band of Eu(2+) doped K(2)Ca(2)(SO(4))(3) microcrystalline sample observed at ∼436 nm is found to split into two narrow well resolved bands, located at 422 and 445 nm in the nanostructure form of this material. This has been attributed to the reduction in the crystal field strength of the nanomaterials, which results in widening the energy band gap and splitting the broad 4f(6)5d energy level of Eu(2+). Energy band gap values of the micro and nanocrystalline K(2)Ca(2)(SO(4))(3) samples were also determined by measuring the UV-visible absorption spectra. These values are 3.34 and 3.44 eV for the micro and nanocrystalline samples, respectively. These remarkable results suggest that activators having wide emission bands might be subjected to weak crystal strength via nanostructure materials to modify their electronic transitions. This might prove a powerful technique for producing new-advanced materials for use in the fields of solid state lasers and optoelectronic devises. PMID:20386964

  4. Dialkylthio Substitution: An Effective Method to Modulate the Molecular Energy Levels of 2D-BDT Photovoltaic Polymers.

    PubMed

    Yao, Huifeng; Zhang, Hao; Ye, Long; Zhao, Wenchao; Zhang, Shaoqing; Hou, Jianhui

    2016-02-17

    Dialkylthio-substituted thienyl-benzodithiophene (BDT-DST) was designed and synthesized as a building block to modulate the molecular levels of the conjugated polymers, and three copolymers named PDST-BDD, PDST-TT and PDST-DPP were prepared and applied in polymer solar cells (PSCs). Theoretical calculations and electrochemical cyclic voltammetry (CV) measurement suggested that the dialkylthio group could decrease the molecular energy levels of the resulting polymers distinctly. The open-circuit voltage (VOC) of PSC devices based on PDST-BDD, PDST-TT, and PDST-DPP are as high as 1.0, 0.98, and 0.88 V, respectively, which are ∼0.15 V higher than those of the corresponding alky-substituted analogues. Moreover, the influence of the dialkylthio group on the absorption spectra, crystalline properties, hole mobilities, and blend morphologies of the polymers was also investigated. The results indicate that the dialkythio substitution is an effective method to modulate the molecular energy levels and that the BDT-DST unit has potential for constructing high-efficiency photovoltaic polymers. PMID:26359953

  5. Probing the Crystal Structure, Composition-Dependent Absolute Energy Levels, and Electrocatalytic Properties of Silver Indium Sulfide Nanostructures.

    PubMed

    Saji, Pintu; Ganguli, Ashok K; Bhat, Mohsin A; Ingole, Pravin P

    2016-04-18

    The absolute electronic energy levels in silver indium sulfide (AIS) nanocrystals (NCs) with varying compositions and crystallographic phases have been determined by using cyclic voltammetry. Different crystallographic phases, that is, metastable cubic, orthorhombic, monoclinic, and a mixture of cubic and orthorhombic AIS NCs, were studied. The band gap values estimated from the cyclic voltammetry measurements match well with the band gap values calculated from the diffuse reflectance spectra measurements. The AIS nanostructures were found to show good electrocatalytic activity towards the hydrogen evolution reaction (HER). Our results clearly establish that the electronic and electrocatalytic properties of AIS NCs are strongly sensitive to the composition and crystal structure of AIS NCs. Monoclinic AIS was found to be the most active HER electrocatalyst, with electrocatalytic activity that is almost comparable to the MoS2 -based nanostructures reported in the literature, whereas cubic AIS was observed to be the least active of the studied crystallographic phases and compositions. In view of the HER activity and electronic band structure parameters observed herein, we hypothesize that the Fermi energy level of AIS NCs is an important factor that decides the electrocatalytic efficiency of these nanocomposites. The work presented herein, in addition to being the first of its kind regarding the composition and phase-dependence of electrochemical aspects of AIS NCs, also presents a simple solvothermal method for the synthesis of different crystallographic phases with various Ag/In molar ratios. PMID:26812447

  6. Assessment of chromium tripicolinate supplementation and dietary energy level and source on growth, carcass, and blood criteria in growing pigs.

    PubMed

    van de Ligt, C P A; Lindemann, M D; Cromwell, G L

    2002-02-01

    Two experiments were conducted to evaluate potential interactive effects of supplemental Cr and dietary energy supply in growing pigs. Experiment 1 used 36 individually penned barrows, 25 to 65 kg, in a 2 x 3 factorial arrangement of supplemental Cr (0 or 200 ppb) and energy level (70, 80, or 90% of ME requirement). A corn-soybean meal basal diet was designed to supply all protein, mineral, and vitamin needs and 70% of the estimated ME need at 70% of ad libitum feed intake. Additional energy to 80% or 90% of the ME requirement was provided by a cornstarch/corn oil blend. In Exp. 2, 30 individually penned barrows, 23 to 68 kg, were used in a 2 x 4 factorial arrangement of supplemental Cr (0 or 200 ppb) and added energy source (none, cornstarch, corn oil, or choice white grease) with basal diets identical to Exp. 1. The various energy sources were added to 90% of the ME requirement. In both experiments, growth data were collected over a 50-d period and pigs were killed at 70.1 kg. Increasing energy levels increased (linear, P < 0.01) ADG, average backfat thickness, 10th rib backfat thickness, and cooler shrink and decreased (linear, P < 0.01) longissimus muscle area in Exp. 1. Carcass composition increased (linear, P < 0.01) in lipid and decreased in protein, water, and protein:lipid ratio in response to increasing ME levels. Similar results were observed in Exp. 2 in response to added energy, regardless of the energy source used. In response to ME, linear increases (P < 0.05) in plasma insulin concentration before feeding and after feeding were observed in Exp. 1. In Exp. 2, plasma insulin concentration was lower for the basal diet before feeding (P < 0.05) and higher for the starch diet after feeding (P < 0.01); insulin:glucose ratio increased (P < 0.01) after feeding for starch compared to oil and fat. No consistent effect of Cr or Cr x ME level on performance or carcass was observed (P > 0.10) in these experiments. Similarly, no Cr effect or Cr x ME interaction

  7. Resonance energy transfer based on shallow and deep energy levels of biotin-polyethylene glycol/polyamine stabilized CdS quantum dots

    NASA Astrophysics Data System (ADS)

    Lü, W.; Tokuhiro, Y.; Umezu, I.; Sugimura, A.; Nagasaki, Y.

    2006-10-01

    Fluorescent resonance energy transfer between the poly(ethylene glycol)-b-poly(2-(N ,N-dimethylamino)ethyl methacrylate) stabilized CdS quantum dots (QDs) and texas-red streptavidin was observed. We propose a four-state model to explain photoluminescence (PL) process of CdS QDs and suggest that there are two emission processes originated from shallow and deep trap energy levels corresponding to fast and slow components of PL decay, respectively. Energy transfer mechanism was discussed based on Dexter theory [J. Chem. Phys. 21, 863 (1953)] and the proposed four-state model. It is found that the energy transfer efficiency of deep energy level is higher than that of shallow energy level. The calculated distance between QD and texas red with the parameters of shallow energy level is the same with that of deep level, which indicates that the proposed model is reasonable for explaining the PL dynamics of CdS QDs.

  8. Improved optimization of perturbation theory: Applications to the oscillator energy levels and Bose-Einstein condensate critical temperature

    NASA Astrophysics Data System (ADS)

    Kneur, Jean-Loïc; Neveu, André; Pinto, Marcus B.

    2004-05-01

    Improving perturbation theory via a variational optimization has generally produced in higher orders an embarrassingly large set of solutions, most of them unphysical (complex). We introduce an extension of the optimized perturbation method which leads to a drastic reduction of the number of acceptable solutions. The properties of this method are studied and it is then applied to the calculation of relevant quantities in different ϕ4 models, such as the anharmonic oscillator energy levels and the critical Bose-Einstein condensation temperature shift Δ Tc recently investigated by various authors. Our present estimates of Δ Tc , incorporating the most recently available six and seven loop perturbative information, are in excellent agreement with all the available lattice numerical simulations. This represents a very substantial improvement over previous treatments.

  9. Electronic energy level and intensity correlations in the spectra of the trivalent actinide aquo ions. III. Bk/sup 3 +/

    SciTech Connect

    Carnall, W.T.; Beitz, J.V.; Crosswhite, H.

    1984-03-15

    The solution absorption spectrum of Bk/sup 3 +/(aquo) was measured and the observed band structure interpreted in terms of a free-ion energy level model. The band intensities were successfully analyzed using the Judd--Ofelt theory for transitions within the f/sup tsN/ configuration. Parameters of the theory were then used to compute fluorescence branching ratios from most probable fluorescing states, and an experimental search was successful in yielding evidence for a transition from one excited state to the ground state in D/sub 2/O solvent. Absorption bands attributed to f ..-->.. d transitions were observed and an interpretation of the electronic structure is presented. Band intensities were compared to those observed for Tb/sup 3 +/(aquo).

  10. SYSTEMATIC CALCULATIONS OF ENERGY LEVELS AND TRANSITION RATES OF C-LIKE IONS WITH Z = 13-36

    SciTech Connect

    Wang, K.; Li, D. F.; Liu, H. T.; Han, X. Y.; Duan, B.; Li, C. Y.; Li, J. G.; Yan, J.; Guo, X. L.; Chen, C. Y.

    2015-01-01

    Based on systematic calculations using a combined relativistic configuration interaction and a many-body perturbation theory (MBPT) approach, we provide a complete and consistent data set for 46 levels belonging to the 2s {sup 2}2p {sup 2}, 2s2p {sup 3}, 2p {sup 4}, 2s {sup 2}2p3s, 2s {sup 2}2p3p, and 2s {sup 2}2p3d configurations in C-like ions with 13 ≤ Z ≤ 36. The data set includes energy levels as well as electric dipole, magnetic dipole, electric quadrupole, and magnetic quadrupole transition properties. Extensive comparisons with available observed and calculated results are made and indicate that the present MBPT calculations are highly accurate. The present data set can be used reliably for many purposes, such as the line identification of observed spectra, and modeling and diagnostics of astrophysical and fusion plasmas.

  11. VizieR Online Data Catalog: Energy levels & transition rates of Be-like ions (Wang+, 2015)

    NASA Astrophysics Data System (ADS)

    Wang, K.; Guo, X. L.; Liu, H. T.; Li, D. F.; Long, F. Y.; Han, X. Y.; Duan, B.; Li, J. G.; Huang, M.; Wang, Y. S.; Hutton, R.; Zou, Y. M.; Zeng, J. L.; Chen, C. Y.; Yan, J.

    2015-08-01

    We report calculations of energy levels and radiative rates for transitions among the lowest 116 fine-structure levels arising from the n<=5 configurations in Be-like ions with Z=10-30. The wavelengths, oscillator strengths, line strengths, and radiative rates for all possible electric dipole, magnetic dipole, electric quadrupole, and magnetic quadrupole transitions among the 116 levels have been calculated using the combined configuration interaction and many-body perturbation method. The accuracy of the results is determined through extensive comparisons with existing laboratory measurements and theoretical results. The present complete set of results should be of great help in line identification and the interpretation of spectra, as well as in the modeling and diagnostics of astrophysical and fusion plasmas. (2 data files).

  12. Photoluminescence Analysis of Energy Level on Li-Doped ZnO Nanowires Grown by a Hydrothermal Method

    NASA Astrophysics Data System (ADS)

    Hyo Lee, Sang; Lee, Jun Seok; Ko, Won Bae; Inn Sohn, Jung; Cha, Seung Nam; Kim, Jong Min; Park, Young Jun; Hong, Jin Pyo

    2012-09-01

    The optical and structural properties of Li-doped ZnO nanowires grown by a hydrothermal method are reported herein. The low-temperature and temperature-dependent photoluminescence spectra clearly exhibited emission peaks that confirmed the presence of a lithium impurity as an acceptor dopant. Particularly, the acceptor energy level of the Li dopant was estimated to be 121 meV from the PL spectra. This value was also indicated from an Arrhenius plot of the integrated PL intensity of the A°X emission as a function of temperature. These results are in agreement with theoretical and experimental results of previously considered p-type dopants reported in other studies.

  13. Photoluminescence Analysis of Energy Level on Li-Doped ZnO Nanowires Grown by a Hydrothermal Method

    NASA Astrophysics Data System (ADS)

    Lee, Sang Hyo; Lee, Jun Seok; Ko, Won Bae; Sohn, Jung Inn; Cha, Seung Nam; Kim, Jong Min; Park, Young Jun; Hong, Jin Pyo

    2012-09-01

    The optical and structural properties of Li-doped ZnO nanowires grown by a hydrothermal method are reported herein. The low-temperature and temperature-dependent photoluminescence spectra clearly exhibited emission peaks that confirmed the presence of a lithium impurity as an acceptor dopant. Particularly, the acceptor energy level of the Li dopant was estimated to be 121 meV from the PL spectra. This value was also indicated from an Arrhenius plot of the integrated PL intensity of the A\\circX emission as a function of temperature. These results are in agreement with theoretical and experimental results of previously considered p-type dopants reported in other studies.

  14. Modeling of trap-assisted tunneling on performance of charge trapping memory with consideration of trap position and energy level

    NASA Astrophysics Data System (ADS)

    Lun, Zhi-Yuan; Li, Yun; Zhao, Kai; Du, Gang; Liu, Xiao-Yan; Wang, Yi

    2016-08-01

    In this work, the trap-assisted tunneling (TAT) mechanism is modeled as a two-step physical process for charge trapping memory (CTM). The influence of the TAT mechanism on CTM performance is investigated in consideration of various trap positions and energy levels. For the simulated CTM structure, simulation results indicate that the positions of oxide traps related to the maximum TAT current contribution shift towards the substrate interface and charge storage layer interface during time evolutions in programming and retention operations, respectively. Lower programming voltage and retention operations under higher temperature are found to be more sensitive to tunneling oxide degradation. Project supported by the National Natural Science Foundation of China (Grant Nos. 61404005, 61421005, and 91434201).

  15. Energy level inequalities in a {open_quote}{open_quote}wrinkled{close_quote}{close_quote} quarkonium potential

    SciTech Connect

    Bambah, B.A.; Dharamvir, K.; Sharma, A.C.

    1996-04-01

    The {open_quote}{open_quote}concave{close_quote}{close_quote} downward property of the standard static {ital q{bar q}} potentials leads to the energy level inequalities {ital E}{sub {ital n}+2}{minus}{ital E}{sub {ital n}+1}{lt}{ital E}{sub {ital n}+1}{minus}{ital E}{sub {ital n}} in the quarkonium mass spectrum. However, this inequality is experimentally observed to be reversed for {ital n}=2 in charmonium and {ital n}=3 in bottomonium, a fact that is inexplicable in terms of any known concave downward potential. We attempt to explain this by allowing for the violation of the concavity condition in a small interval, i.e., a {open_quote}{open_quote}wrinkle{close_quote}{close_quote} in some recently proposed quarkonium potentials. {copyright} {ital 1996 The American Physical Society.}

  16. The interplay between interface structure, energy level alignment and chemical bonding strength at organic-metal interfaces.

    PubMed

    Willenbockel, M; Lüftner, D; Stadtmüller, B; Koller, G; Kumpf, C; Soubatch, S; Puschnig, P; Ramsey, M G; Tautz, F S

    2015-01-21

    What do energy level alignments at metal-organic interfaces reveal about the metal-molecule bonding strength? Is it permissible to take vertical adsorption heights as indicators of bonding strengths? In this paper we analyse 3,4,9,10-perylene-tetracarboxylic acid dianhydride (PTCDA) on the three canonical low index Ag surfaces to provide exemplary answers to these questions. Specifically, we employ angular resolved photoemission spectroscopy for a systematic study of the energy level alignments of the two uppermost frontier states in ordered monolayer phases of PTCDA. Data are analysed using the orbital tomography approach. This allows the unambiguous identification of the orbital character of these states, and also the discrimination between inequivalent species. Combining this experimental information with DFT calculations and the generic Newns-Anderson chemisorption model, we analyse the alignments of highest occupied and lowest unoccupied molecular orbitals (HOMO and LUMO) with respect to the vacuum levels of bare and molecule-covered surfaces. This reveals clear differences between the two frontier states. In particular, on all surfaces the LUMO is subject to considerable bond stabilization through the interaction between the molecular π-electron system and the metal, as a consequence of which it also becomes occupied. Moreover, we observe a larger bond stabilization for the more open surfaces. Most importantly, our analysis shows that both the orbital binding energies of the LUMO and the overall adsorption heights of the molecule are linked to the strength of the chemical interaction between the molecular π-electron system and the metal, in the sense that stronger bonding leads to shorter adsorption heights and larger orbital binding energies. PMID:25475998

  17. Rovibrational energy levels of the F(-)(H2O) and F(-)(D2O) complexes.

    PubMed

    Sarka, János; Lauvergnat, David; Brites, Vincent; Császár, Attila G; Léonard, Celine

    2016-06-29

    The variational nuclear-motion codes ElVibRot and GENIUSH have been used to compute rotational-vibrational states of the F(-)(H2O) anion and its deuterated isotopologue, F(-)(D2O), employing a full-dimensional, semiglobal potential energy surface (PES) called SLBCL, developed as part of this study for the ground electronic state of the complex. The PES is determined from all-electron, explicitly correlated coupled-cluster singles, doubles, and connected triples [CCSD(T)-F12a] computations with an atom-centered, fixed-exponent Gaussian basis set of cc-pCVTZ-F12 quality. The SLBCL PES accurately reproduces the two equivalent minima of the complex, the corresponding transition barrier of C2v point-group symmetry, as well as the proton transfer and the dissociation asymptotes towards the products HF + OH(-) and F(-) + H2O, respectively. The code ElVibRot has been updated so that it can use curvilinear internal coordinates corresponding to a reaction path. The variationally computed vibrational energy levels are compared to relevant experimental and previously determined first-principles results. The vibrational states reveal the presence of pronounced anharmonic effects and considerable intermode couplings resulting in strong resonances, involving in particular the HOH bend and the ionic OH stretch motions. Tunneling results in particularly significant splittings for F(-)(H2O); as expected, the splittings are orders of magnitude smaller for the F(-)(D2O) molecule. The rovibrational energy levels reveal that, despite the large-amplitude vibrational motions, the rotations of F(-)(H2O) basically follow rigid-rotor characteristics. PMID:27306786

  18. How to Calculate Molecular Column Density

    NASA Astrophysics Data System (ADS)

    Mangum, Jeffrey G.; Shirley, Yancy L.

    2015-03-01

    The calculation of the molecular column density from molecular spectral (rotational or ro-vibrational) transition measurements is one of the most basic quantities derived from molecular spectroscopy. Starting from first principles where we describe the basic physics behind the radiative and collisional excitation of molecules and the radiative transfer of their emission, we derive a general expression for the molecular column density. As the calculation of the molecular column density involves a knowledge of the molecular energy level degeneracies, rotational partition functions, dipole moment matrix elements, and line strengths, we include generalized derivations of these molecule-specific quantities. Given that approximations to the column density equation are often useful, we explore the optically thin, optically thick, and low-frequency limits to our derived general molecular column density relation. We also evaluate the limitations of the common assumption that the molecular excitation temperature is constant and address the distinction between beam-averaged and source-averaged column densities. As non-LTE approaches to the calculation of molecular spectral line column density have become quite common, we summarize non-LTE models that calculate molecular cloud volume densities, kinetic temperatures, and molecular column densities. We conclude our discussion of the molecular column density with worked examples for C18O, C17O, N2H+, NH3, and H2CO. Ancillary information on some subtleties involving line profile functions, conversion between integrated flux and brightness temperature, the calculation of the uncertainty associated with an integrated intensity measurement, the calculation of spectral line optical depth using hyperfine or isotopologue measurements, the calculation of the kinetic temperature from a symmetric molecule excitation temperature measurement, and relative hyperfine intensity calculations for NH3 are presented in appendices. The intent of

  19. Relativistic Many-body Moller-Plesset Perturbation Theory Calculations of the Energy Levels and Transition Probabilities in Na- to P-like Xe Ions

    SciTech Connect

    Vilkas, M J; Ishikawa, Y; Trabert, E

    2007-03-27

    Relativistic multireference many-body perturbation theory calculations have been performed on Xe{sup 43+}-Xe{sup 39+} ions, resulting in energy levels, electric dipole transition probabilities, and level lifetimes. The second-order many-body perturbation theory calculation of energy levels included mass shifts, frequency-dependent Breit correction and Lamb shifts. The calculated transition energies and E1 transition rates are used to present synthetic spectra in the extreme ultraviolet range for some of the Xe ions.

  20. Anomalous tunneling in carbon/alkane/TiO(2)/gold molecular electronic junctions: energy level alignment at the metal/semiconductor interface.

    PubMed

    Yan, Haijun; McCreery, Richard L

    2009-02-01

    Carbon/TiO(2)/gold electronic junctions show slightly asymmetric electronic behavior, with higher current observed in current density (J)/voltage (V) curves when carbon is biased negative with respect to the gold top contact. When a approximately 1-nm-thick alkane film is deposited between the carbon and TiO(2), resulting in a carbon/alkane/TiO(2)/gold junction, the current increases significantly for negative bias and decreases for positive bias, thus creating a much less symmetric J/V response. Similar results were obtained when SiO(2) was substituted for the alkane layer, but Al(2)O(3) did not produce the effect. The observation that, by the addition of an insulating material between carbon and TiO(2), the junction becomes more conductive is unexpected and counterintuitive. Kelvin probe measurements revealed that while the apparent work function of the pyrolyzed photoresist film electrode is modulated by surface dipoles of different surface-bound molecular layers, the anomalous effect is independent of the direction of the surface dipole. We propose that by using a nanometer-thick film with a low dielectric constant as an insertion layer, most of the applied potential is dropped across this thin film, thus permitting alignment between the carbon Fermi level and the TiO(2) conduction band. Provided that the alkane layer is sufficiently thin, electrons can directly tunnel from carbon to the TiO(2) conduction band. Therefore, the electron injection barrier at the carbon/TiO(2) interface is effectively reduced by this energy-level alignment, resulting in an increased current when carbon is biased negative. The modulation of injection barriers by a low-kappa molecular layer should be generally applicable to a variety of materials used in micro- and nanoelectronic fabrication. PMID:20353235

  1. Energy Levels and Intensity Parameters of Ho3(+) Ions in Y3Al5O12 and Lu3Al5O12

    NASA Technical Reports Server (NTRS)

    Walsh, Brian M.; Grew, Gary W.; Barnes, Norman P.

    2006-01-01

    The energy levels of the trivalent lanthanide Ho(sup 3+) in Y3Al5O12 (YAG) and Lu3Al5O12 (LuAG) have been measured. The Stark split levels for the first nine Ho manifolds in these materials have been measured, and the results have been fit to a free ion plus crystal field Hamiltonian to generate a theoretical set of energy levels. Crystal field parameters were varied to determine the best fit between experimental and theoretical energy levels. The energy levels of Ho:LuAG are seen to be very similar to those in Ho:YAG. However, subtle changes resulting from replacing Y(sup 3+) with Lu(sup 3+) in the garnet crystal Y3Al5O12 result in different transition wavelengths in LuAG. This has implications for Ho (sup 5)I7yields (sup 5)I8 lasers operating at approximately 2.1 micrometers. Although the energy levels have been measured previously in Ho:YAG, they have not been measured in Ho:LuAG. A comparison of the energy levels in Ho:YAG measured here show some discrepancies with previous measurements. The consistency of the energy level placement between Ho:LuAG and Ho:YAG indicate that the earlier studies may have some errors in the assignments. Finally, a Judd-Ofelt analysis is performed on Ho:YAG and Ho:LuAG to determine the intensity parameters, and thus, the transition probabilities and branching ratios of the first eight excited manifolds.

  2. Distant electrostatic interactions modulate the free energy level of Q{sub A}{sup -} in the photosynthetic reaction center

    SciTech Connect

    Miksovska, J.; Sebban, P.; Tandori, J.

    1996-12-03

    In the reaction centers from the purple photosynthetic bacterium Rhodobacter capsulatus, we have determined that residue L212Glu, situated near the secondary quinone acceptor Q{sub B}, modulates the free energy level of the reduced primary quinone molecule A{sub A}{sup -} at high pH. Even though the distance between L212Glu and Q{sub A} is 17 {angstrom}, our results indicate an apparent interaction energy between them of 30 {plus_minus} 18 meV. This interaction was measured by quantitating the stoichiometry of partial proton uptake upon formation of Q{sub A}{sup -} as a function of pH in four mutant strains which lack L212Glu, in comparison with the wild type. Below pH 7.5, the stoichiometry of proton uptake form all stains is nearly superimposable with that of the wild type. However, at variance with the wild type, reaction centers from all strains that lack L212Glu fail to take up protons above pH 9. The lack of a change in the free energy level is confirmed by the determination of the pH dependence of the rate (k{sub AP}) of P{sup +}Q{sub A}{sup -} charge recombination in the reaction centers where the native Q{sub A} is replaced by quinones having low redox potentials. Our data show that the ionization state of L212Glu, either on its own or via interactions with closely associated ionizable groups, is mainly involved in the proton uptake at high pH by reaction centers in the PQ{sub A}{sup -} state. This suggests that the formation of the Q{sub A}{sup -} semiquinone state induces shifts in pK{sub a}S of residues in the Q{sub B} proteic environment. This long-distance influence of ionization states is a mechanism which would facilitate electron transfer from Q{sub A} to Q{sub B} on the first and second flashes. The functional communication between the two quinone protein pockets may involve the iron-ligand complex which spans the distance between them. 48 refs., 4 figs.

  3. Production Density Diffusion Equation Propagation and Production

    NASA Astrophysics Data System (ADS)

    Shirai, Kenji; Amano, Yoshinori

    When we call the production flow to transition elements in the next step in the process of product manufactured one, the production flow is considered to be displaced in the direction of the unit production density. Density and production, as captured from different perspectives, also said production costs per unit of production. However, it is assumed that contributed to the production cost of manufacturing 100 percent. They may not correspond to the physical propagation conditions after each step of the production density, the equations governing the manufacturing process, which is intended to be represented by a single diffusion equation. We can also apply the concept of energy levels in statistical mechanics, production density function, in other words, in statistical mechanics “place” that if you use the world of manufacturing and production term. If the free energy in this production (potential) that are consuming the substance is nothing but the entropy production. That is, productivity is defined as the entropy production has to be. Normally, when we increase the number of production units, the product nears completion at year-end number of units completed and will aim to be delivered to the contractor from the turnover order. However, if you stop at any number of units, that will increase production density over time. Thus, the diffusion does not proceed from that would be irreversible. In other words, the congestion will occur in production. This fact and to report the results of analysis based on real data.

  4. Impact of MoO3 interlayer on the energy level alignment of pentacene-C60 heterostructure

    NASA Astrophysics Data System (ADS)

    Zou, Ye; Mao, Hongying; Meng, Qing; Zhu, Daoben

    2016-02-01

    Using in situ ultraviolet photoelectron spectroscopy, the electronic structure evolutions at the interface between pentacene and fullerene (C60), a classical organic donor-acceptor heterostructure in organic electronic devices, on indium-tin oxide (ITO) and MoO3 modified ITO substrates have been investigated. The insertion of a thin layer MoO3 has a significant impact on the interfacial energy level alignment of pentacene-C60 heterostructure. For the deposition of C60 on pentacene, the energy difference between the highest occupied molecular orbital of donor and the lowest unoccupied molecular orbital of acceptor (HOMOD-LUMOA) offset of C60/pentacene heterostructure increased from 0.86 eV to 1.54 eV after the insertion of a thin layer MoO3 on ITO. In the inverted heterostructrure where pentacene was deposited on C60, the HOMOD-LUMOA offset of pentacene/C60 heterostructure increased from 1.32 to 2.20 eV after MoO3 modification on ITO. The significant difference of HOMOD-LUMOA offset shows the feasibility to optimize organic electronic device performance through interfacial engineering approaches, such as the insertion of a thin layer high work function MoO3 films.

  5. Evidence for Multi-photon transitions between energy levels in a large Current-Biased Magnesium Diboride Josephson Heterojunction

    NASA Astrophysics Data System (ADS)

    Ramos, Roberto; Carabello, Steven; Lambert, Joseph; Cunnane, Daniel; Dai, Wenqing; Chen, Ke; Li, Qi; Xi, Xiaoxing

    2013-03-01

    When photons are strongly coupled to a quantum system, multiphoton transitions can be observed between two energy levels when the quantum energy of the exciting radiation, multiplied by an integer, matches the level spacing. This phenomenon can be observed in Josephson junction qubits exposed to weak microwave radiation at very low temperatures. At microwave resonance, the transition probability of a junction from superconducting to normal state is enhanced and these are used to map multiphoton transitions. We report observation of single- and multi-photon transitions between ground and first excited states in current-biased MgB2 thin film junctions by applying RF with frequencies between 0.5 and 3 Ghz. These large (up to 0.2mm x 0.3 mm) junctions consist of an MgB2 electrode insulated by native oxide from a lead (Pb) or tin (Sn) counter-electrode, and have areas at least 600 times bigger than Nb junctions previously shown to exhibit multiphoton transitions. The data is consistent with theoretical models of junctions behaving in the quantum limit and show anharmonicity of the junction potential when biased near the critical current.

  6. Novel patterns of torsion-inversion-rotation energy levels in the ν11 asymmetric CH-stretch spectrum of methylamine.

    PubMed

    Dawadi, Mahesh B; Michael Lindsay, C; Chirokolava, Andrei; Perry, David S; Xu, Li-Hong

    2013-03-14

    The high-resolution infrared spectrum of methylamine (CH3NH2) has been recorded using slit-jet direct absorption spectroscopy in the ν11 CH-stretch region (2965-3005 cm(-1)) with a resolution of 0.0025 cm(-1). The 621 lines assigned by ground state combination differences represent 27 substates with |K(')| ≤ 2 for the A, B, E1, and E2 symmetries. The spectrum of CH3NH2 is complicated by torsion and inversion tunneling connecting six equivalent minima. The upper states K(') = 0, ± 1 for E1 and E2 are substantially perturbed by "dark" states. The result in the spectrum is multiplets of 2 or 3 states with mixed bright∕dark character. The analysis of the spectrum reveals two qualitative differences in the energy level pattern relative to the vibrational ground state and relative to available data on the lower frequency vibrations (NH2 wag and CN stretch). First at J(') = 0, there is a different ordering of the levels connected by torsion-inversion tunneling. Second, the low-J splittings indicative of torsion-rotation coupling are greatly reduced in the ν11 excited state relative to the vibrational ground state for both the E1 and E2 species, suggesting the partial suppression of torsional tunneling in the ν11 CH-stretch excited state. PMID:23514487

  7. Intensity and Energy Level Analysis of the Vacuum Ultraviolet Spectrum of Four Times Ionize Nickel (Ni V)

    NASA Astrophysics Data System (ADS)

    Ward, Jacob Wolfgang; Nave, Gillian

    2016-01-01

    Recent measurements of four times ionized iron and nickel (Fe V & Ni V) wavelengths in the vacuum ultraviolet (VUV) have been taken using the National Institute for Standards and Technology (NIST) Normal Incidence Vacuum Spectrograph (NIVS) with a sliding spark light source with invar electrodes. The wavelengths observed in those measurements make use of high resolution photographic plates with the majority of observed lines having uncertainties of approximately 3mÅ. In addition to observations made with photographic plates, the same wavelength region was observed with phosphor image plates, which have been demonstrated to be accurate as a method of intensity calibration when used with a deuterium light source. This work will evaluate the use of phosphor image plates and deuterium lamps as an intensity calibration method for the Ni V spectrum in the 1200-1600Å region of the VUV. Additionally, by pairing the observed wavelengths of Ni V with accurate line intensities, it is possible to create an energy level optimization for Ni V providing high accuracy Ritz wavelengths. This process has previously been applied to Fe V and produced Ritz wavelengths that agreed with the above experimental observations.

  8. Energy level alignment of electrically doped hole transport layers with transparent and conductive indium tin oxide and polymer anodes

    NASA Astrophysics Data System (ADS)

    Fehse, Karsten; Olthof, Selina; Walzer, Karsten; Leo, Karl; Johnson, Robert L.; Glowatzki, Hendrik; Bröker, Benjamin; Koch, Norbert

    2007-10-01

    Using ultraviolet photoemission spectroscopy, we investigated the energy level alignment at the interfaces of typical anodes used in organic electronics, indium tin oxide (ITO) and poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS), with the oligomeric hole transport material N ,N,N',N'-tetrakis(4-methoxyphenyl)-benzidine (MeO-TPD), and studied the influence of electrical interface doping by the strong electron acceptor tetrafluoro tetracyanoquinodimethane (F4-TCNQ). The fundamentally different anode materials with work functions of 4.40eV (ITO) and 4.85eV (PEDOT:PSS) show different hole injection barriers, which also depend on the thickness of the F4-TCNQ interface dopant layer. PEDOT:PSS anodes exhibit a consistently lower hole injection barrier to MeO-TPD compared to ITO by 0.1eV. We attribute this low hole injection barrier to additional charge transfer reactions at the PEDOT:PSS/MeO-TPD interface. In contrast, the deposition of the electron acceptor at the interface helps significantly to lower the hole injection barrier for ITO anodes.

  9. Reexamination of the Energy Levels of 15F by 14O + 1H ElasticResonance Scattering with BEARS

    SciTech Connect

    Guo, F.Q.; Powell, J.; Lee, D.W.; Leitner, D.; McMahan, M.A.; Moltz, D.M.; O'Neil, J.P.; Perajarvi, K.; Phair, L.; Ramsey, C.A.; Xu,X.J.; Cerny, Joseph

    2005-05-30

    The energy levels of 15F have been measured by the p(14O,p)14O reaction. The 120 MeV 14O radioactive ion beam was produced by the BEARS coupled cyclotron system at an intensity averaging 1x104 particles/second on target. Energy calibration was obtained using resonances from the p(14N,p)14N reaction. The two lowest resonances in 15F were fitted with an R-matrix calculation. The fit to the ground state had Jp = 1/2+ at 1.23+-0.05 MeV (width 0.5-0.84 MeV), and the first excited state was Jp=5/2+ at 2.81+-0.02 MeV (width 0.30+-0.06 MeV), both relative to the mass-energy of the proton and 14O. The 15F ground state energy supports the disappearance of the Z=8 proton magic number for odd Z, Tz=-3/2 nuclei.

  10. A new accurate ground-state potential energy surface of ethylene and predictions for rotational and vibrational energy levels

    NASA Astrophysics Data System (ADS)

    Delahaye, Thibault; Nikitin, Andrei; Rey, Michaël; Szalay, Péter G.; Tyuterev, Vladimir G.

    2014-09-01

    In this paper we report a new ground state potential energy surface for ethylene (ethene) C2H4 obtained from extended ab initio calculations. The coupled-cluster approach with the perturbative inclusion of the connected triple excitations CCSD(T) and correlation consistent polarized valence basis set cc-pVQZ was employed for computations of electronic ground state energies. The fit of the surface included 82 542 nuclear configurations using sixth order expansion in curvilinear symmetry-adapted coordinates involving 2236 parameters. A good convergence for variationally computed vibrational levels of the C2H4 molecule was obtained with a RMS(Obs.-Calc.) deviation of 2.7 cm-1 for fundamental bands centers and 5.9 cm-1 for vibrational bands up to 7800 cm-1. Large scale vibrational and rotational calculations for 12C2H4, 13C2H4, and 12C2D4 isotopologues were performed using this new surface. Energy levels for J = 20 up to 6000 cm-1 are in a good agreement with observations. This represents a considerable improvement with respect to available global predictions of vibrational levels of 13C2H4 and 12C2D4 and rovibrational levels of 12C2H4.

  11. There may be Fermi Energy levels in the hollow interiors of Nanotubes that would allow for a type of Quantum

    NASA Astrophysics Data System (ADS)

    Kriske, Richard

    2011-04-01

    There may be Fermi Energy levels that would allow for easy travel by Atoms, Molecules and Particles, in the hollow interior of Nanotubes. This may result in a Quantum Mechanical explaination of Capillary Action, and it may result in devices could take advantage of the idea that it takes no energy to rise in a Capillary tube, only in leaving it. This no-energy conjecture of Capillarity sounds very much like the idea that Electrons in obitals lose no Energy staying in orbit, only in changing orbits.It is this conjecture that may reveal that a Fermi Energy state is essentially in a weak orbital. This weak orbital could be exploited to store Anti-matter for instance. More profoundly it clearly shows how the Quantum Mechanical states meld smoothly into Classical Physics. It also reveals how extremely efficient Classical Machines could be constructed to take advantage of this spontaneous action. Say a tube could be designed to nudge electrons out of a weak obital in one place, sent down the tube (which is another weak orbital) and deposited in a weak orbital of another very distant Atom, apparently with little or perhaps no work being done, as long as the orbitals are the same energy. This may already exist in some Biological systems. Although more experimentation is needed, this would be the breakthrough that is needed to unify Classical and Quantum Mechanics.

  12. Impact of MoO3 interlayer on the energy level alignment of pentacene-C60 heterostructure.

    PubMed

    Zou, Ye; Mao, Hongying; Meng, Qing; Zhu, Daoben

    2016-02-28

    Using in situ ultraviolet photoelectron spectroscopy, the electronic structure evolutions at the interface between pentacene and fullerene (C60), a classical organic donor-acceptor heterostructure in organic electronic devices, on indium-tin oxide (ITO) and MoO3 modified ITO substrates have been investigated. The insertion of a thin layer MoO3 has a significant impact on the interfacial energy level alignment of pentacene-C60 heterostructure. For the deposition of C60 on pentacene, the energy difference between the highest occupied molecular orbital of donor and the lowest unoccupied molecular orbital of acceptor (HOMO(D)-LUMO(A)) offset of C60/pentacene heterostructure increased from 0.86 eV to 1.54 eV after the insertion of a thin layer MoO3 on ITO. In the inverted heterostructrure where pentacene was deposited on C60, the HOMO(D)-LUMO(A) offset of pentacene/C60 heterostructure increased from 1.32 to 2.20 eV after MoO3 modification on ITO. The significant difference of HOMO(D)-LUMO(A) offset shows the feasibility to optimize organic electronic device performance through interfacial engineering approaches, such as the insertion of a thin layer high work function MoO3 films. PMID:26931717

  13. Accurate Potential Energy Surface, Rovibrational Energy Levels, and Transitions of Ammonia C_{3v} Isotopologues: ^{14}NH_3, ^{15}NH_3, ^{14}ND_3 and ^{14}NT_3

    NASA Astrophysics Data System (ADS)

    Huang, Xinchuan; Schwenke, David W.; Lee, Timothy J.

    2009-06-01

    A further refined, global potential energy surface (PES) is computed for the C_{3v} symmetry isotopologues of ammonia, including ^{14}NH_3, ^{15}NH_3, ^{14}ND_3 and ^{14}NT_3. The refinement procedure was similar to that used in our previously reported PES, but now extends to higher J energy levels and other isotopologues. Both the diagonal Born-Oppenheimer correction and the non-adiabatic correction were included. J=0-6 rovibrational energy levels and transition frequencies of ^{14}NH_3 computed on this PES are in excellent agreement with HITRAN data. Statistics on nearly 4100 transitions and more than 1000 energy levels demonstrate the accuracy achieved by the state-of-the-art "Best Theory + Experiment" strategy. Most transition frequencies are of ±0.01-0.02 cm^{-1} accuracy. Similar accuracy has been found on ^{15}NH_3 J=0-3 rovibrational energy levels. Several transitions and energy levels in HITRAN have been identified as unreliable or suspicious, and some have been re-assigned. For ^{14}ND_3 and ^{14}NT_3, J=0-3 calculations have been performed. Agreement for pure rotation-inversion transitions is nearly perfect, with more reliable energy levels presented. On the other hand, our J=0 results suggest a re-analysis on the ^{14}ND_3 ν_1 band origin is needed. Finally, we will discuss possible future refinements leading to an even better final PES for Ammonia. X. Huang, D.W. Schwenke, and T.J. Lee, J. Chem. Phys. 129, 214304 (2008).

  14. Configuration coordinate energy level diagrams of intervalence and metal-to-metal charge transfer states of dopant pairs in solids.

    PubMed

    Barandiarán, Zoila; Meijerink, Andries; Seijo, Luis

    2015-08-14

    Configuration coordinate diagrams, which are normally used in a qualitative manner for the energy levels of active centers in phosphors, are quantitatively obtained here for intervalence charge transfer (IVCT) states of mixed valence pairs and metal-to-metal charge transfer (MMCT) states of heteronuclear pairs, in solid hosts. The procedure relies on vibrational frequencies and excitation energies of single-ion active centers, and on differences between ion-ligand distances of the donor and the acceptor, which are attainable empirically or through ab initio calculations. The configuration coordinate diagrams of the Yb(2+)/Yb(3+) mixed-valence pair in Yb-doped YAG and the Ce(3+)/Yb(3+) heteronuclear pair in Ce,Yb-codoped YAG, are obtained and described. They are drawn from empirical data of the single-ions and their usefulness is discussed. The first diagram suggests that IVCT states of Yb(2+)/Yb(3+) pairs may play an important role in the quenching of the Yb(3+) emission and it provides the details of the quenching mechanism. The second diagram supports the interpretation recently given for the energy transfer from Ce(3+) to Yb(3+) in Ce,Yb-codoped YAG via a MMCT Ce(4+)-Yb(2+) state and it provides the details. The analyses of the two diagrams suggest the formation of Yb(2+)/Yb(3+) pairs after the Ce(3+)-to-Yb(3+) MMCT, which is responsible for the temperature quenching of the Yb(3+) emission excited via Ce(3+) (4f → 5d) absorption in Ce,Yb-codoped YAG. PMID:26159813

  15. IUPAC critical evaluation of the rotational-vibrational spectra of water vapor, Part III: Energy levels and transition wavenumbers for H216O

    NASA Astrophysics Data System (ADS)

    Tennyson, Jonathan; Bernath, Peter F.; Brown, Linda R.; Campargue, Alain; Császár, Attila G.; Daumont, Ludovic; Gamache, Robert R.; Hodges, Joseph T.; Naumenko, Olga V.; Polyansky, Oleg L.; Rothman, Laurence S.; Vandaele, Ann Carine; Zobov, Nikolai F.; Al Derzi, Afaf R.; Fábri, Csaba; Fazliev, Alexander Z.; Furtenbacher, Tibor; Gordon, Iouli E.; Lodi, Lorenzo; Mizus, Irina I.

    2013-03-01

    This is the third of a series of articles reporting critically evaluated rotational-vibrational line positions, transition intensities, and energy levels, with associated critically reviewed labels and uncertainties, for all the main isotopologues of water. This paper presents experimental line positions, experimental-quality energy levels, and validated labels for rotational-vibrational transitions of the most abundant isotopologue of water, H216O. The latest version of the MARVEL (Measured Active Rotational-Vibrational Energy Levels) line-inversion procedure is used to determine the rovibrational energy levels of the electronic ground state of H216O from experimentally measured lines, together with their self-consistent uncertainties, for the spectral region up to the first dissociation limit. The spectroscopic network of H216O containstwo components, an ortho (o) and a para (p) one. For o-H216O and p-H216O, experimentally measured, assigned, and labeled transitions were analyzed from more than 100 sources. The measured lines come from one-photon spectra recorded at room temperature in absorption, from hot samples with temperatures up to 3000 K recorded in emission, and from multiresonance excitation spectra which sample levels up to dissociation. The total number of transitions considered is 184 667 of which 182 156 are validated: 68 027 between para states and 114 129 ortho ones. These transitions give rise to 18 486 validated energy levels, of which 10 446 and 8040 belong to o-H216O and p-H216O, respectively. The energy levels, including their labeling with approximate normal-mode and rigid-rotor quantum numbers, have been checked against ones determined from accurate variational nuclear motion computations employing exact kinetic energy operators as well as against previous compilations of energy levels. The extensive list of MARVEL lines and levels obtained are deposited in the supplementary data of this paper, as well as in a distributed information system

  16. Energy level alignment of self-assembled linear chains of benzenediamine on Au(111) from first principles

    NASA Astrophysics Data System (ADS)

    Li, Guo; Rangel, Tonatiuh; Liu, Zhen-Fei; Cooper, Valentino R.; Neaton, Jeffrey B.

    2016-03-01

    Using density functional theory (DFT) with a van der Waals density functional, we calculate the adsorption energetics and geometry of benzenediamine (BDA) molecules on Au(111) surfaces. Our results demonstrate that the reported self-assembled linear chain structure of BDA, stabilized via hydrogen bonds between amine groups, is energetically favored over previously studied monomeric phases. Moreover, using a model, which includes nonlocal polarization effects from the substrate and the neighboring molecules and incorporates many-body perturbation theory calculations within the GW approximation, we obtain approximate self-energy corrections to the DFT highest occupied molecular orbital (HOMO) energy associated with BDA adsorbate phases. We find that, independent of coverage, the HOMO energy of the linear chain phase is lower relative to the Fermi energy than that of the monomer phase, and in good agreement with values measured with ultraviolet photoelectron spectroscopy and x-ray photoelectron spectroscopy.

  17. Density perturbation theory

    SciTech Connect

    Palenik, Mark C.; Dunlap, Brett I.

    2015-07-28

    Despite the fundamental importance of electron density in density functional theory, perturbations are still usually dealt with using Hartree-Fock-like orbital equations known as coupled-perturbed Kohn-Sham (CPKS). As an alternative, we develop a perturbation theory that solves for the perturbed density directly, removing the need for CPKS. This replaces CPKS with a true Hohenberg-Kohn density perturbation theory. In CPKS, the perturbed density is found in the basis of products of occupied and virtual orbitals, which becomes ever more over-complete as the size of the orbital basis set increases. In our method, the perturbation to the density is expanded in terms of a series of density basis functions and found directly. It is possible to solve for the density in such a way that it makes the total energy stationary even if the density basis is incomplete.

  18. Challenges in the simulation of dye-sensitized ZnO solar cells: quantum confinement, alignment of energy levels and excited state nature at the dye/semiconductor interface.

    PubMed

    Amat, Anna; De Angelis, Filippo

    2012-08-14

    We report a first principles density functional theory/time-dependent density functional theory (DFT/TDDFT) computational investigation on a prototypical perylene dye anchored to realistic ZnO nanostructures, approaching the size of the ZnO nanowires used in dye-sensitized solar cells devices. DFT calculations were performed on (ZnO)(n) clusters of increasing size, with n up to 222, of 1.3 × 1.5 × 3.4 nm dimensions, and for the related dye-sensitized models. We show that quantum confinement in the ZnO nanostructures substantially affects the dye/semiconductor alignment of energy levels, with smaller ZnO models providing unfavourable electron injection. An increasing broadening of the dye LUMO is found moving to larger substrates, substantially contributing to the interfacial electronic coupling. TDDFT excited state calculations for the investigated dye@(ZnO)(222) system are fully consistent with experimental data, quantitatively reproducing the red-shift and broadening of the visible absorption spectrum observed for the ZnO-anchored dye compared to the dye in solution. TDDFT calculations on the fully interacting system also introduce a contribution to the dye/semiconductor admixture, due to configurational excited state mixing. Our results highlight the importance of quantum confinement in dye-sensitized ZnO interfaces, and provide the fundamental insight lying at the heart of the associated DSC devices. PMID:22743544

  19. A Dastardly Density Deed.

    ERIC Educational Resources Information Center

    Shaw, Mike

    2003-01-01

    Integrates story telling into a science activity on the density of liquids in order to increase student interest. Shows the relationship between mass and volume ratio and how they determine density. Includes teacher notes. (YDS)

  20. Direct Density Derivative Estimation.

    PubMed

    Sasaki, Hiroaki; Noh, Yung-Kyun; Niu, Gang; Sugiyama, Masashi

    2016-06-01

    Estimating the derivatives of probability density functions is an essential step in statistical data analysis. A naive approach to estimate the derivatives is to first perform density estimation and then compute its derivatives. However, this approach can be unreliable because a good density estimator does not necessarily mean a good density derivative estimator. To cope with this problem, in this letter, we propose a novel method that directly estimates density derivatives without going through density estimation. The proposed method provides computationally efficient estimation for the derivatives of any order on multidimensional data with a hyperparameter tuning method and achieves the optimal parametric convergence rate. We further discuss an extension of the proposed method by applying regularized multitask learning and a general framework for density derivative estimation based on Bregman divergences. Applications of the proposed method to nonparametric Kullback-Leibler divergence approximation and bandwidth matrix selection in kernel density estimation are also explored. PMID:27140943

  1. Information geometric density estimation

    NASA Astrophysics Data System (ADS)

    Sun, Ke; Marchand-Maillet, Stéphane

    2015-01-01

    We investigate kernel density estimation where the kernel function varies from point to point. Density estimation in the input space means to find a set of coordinates on a statistical manifold. This novel perspective helps to combine efforts from information geometry and machine learning to spawn a family of density estimators. We present example models with simulations. We discuss the principle and theory of such density estimation.

  2. Crowding and Density

    ERIC Educational Resources Information Center

    Design and Environment, 1972

    1972-01-01

    Three-part report pinpointing problems and uncovering solutions for the dual concepts of density (ratio of people to space) and crowding (psychological response to density). Section one, A Primer on Crowding,'' reviews new psychological and social findings; section two, Density in the Suburbs,'' shows conflict between status quo and increased…

  3. Measurements of continuum lowering in solid-density plasmas created from elements and compounds

    NASA Astrophysics Data System (ADS)

    Ciricosta, O.; Vinko, S. M.; Barbrel, B.; Rackstraw, D. S.; Preston, T. R.; Burian, T.; Chalupský, J.; Cho, B. I.; Chung, H.-K.; Dakovski, G. L.; Engelhorn, K.; Hájková, V.; Heimann, P.; Holmes, M.; Juha, L.; Krzywinski, J.; Lee, R. W.; Toleikis, S.; Turner, J. J.; Zastrau, U.; Wark, J. S.

    2016-05-01

    The effect of a dense plasma environment on the energy levels of an embedded ion is usually described in terms of the lowering of its continuum level. For strongly coupled plasmas, the phenomenon is intimately related to the equation of state; hence, an accurate treatment is crucial for most astrophysical and inertial-fusion applications, where the case of plasma mixtures is of particular interest. Here we present an experiment showing that the standard density-dependent analytical models are inadequate to describe solid-density plasmas at the temperatures studied, where the reduction of the binding energies for a given species is unaffected by the different plasma environment (ion density) in either the element or compounds of that species, and can be accurately estimated by calculations only involving the energy levels of an isolated neutral atom. The results have implications for the standard approaches to the equation of state calculations.

  4. Measurements of continuum lowering in solid-density plasmas created from elements and compounds.

    PubMed

    Ciricosta, O; Vinko, S M; Barbrel, B; Rackstraw, D S; Preston, T R; Burian, T; Chalupský, J; Cho, B I; Chung, H-K; Dakovski, G L; Engelhorn, K; Hájková, V; Heimann, P; Holmes, M; Juha, L; Krzywinski, J; Lee, R W; Toleikis, S; Turner, J J; Zastrau, U; Wark, J S

    2016-01-01

    The effect of a dense plasma environment on the energy levels of an embedded ion is usually described in terms of the lowering of its continuum level. For strongly coupled plasmas, the phenomenon is intimately related to the equation of state; hence, an accurate treatment is crucial for most astrophysical and inertial-fusion applications, where the case of plasma mixtures is of particular interest. Here we present an experiment showing that the standard density-dependent analytical models are inadequate to describe solid-density plasmas at the temperatures studied, where the reduction of the binding energies for a given species is unaffected by the different plasma environment (ion density) in either the element or compounds of that species, and can be accurately estimated by calculations only involving the energy levels of an isolated neutral atom. The results have implications for the standard approaches to the equation of state calculations. PMID:27210741

  5. Measurements of continuum lowering in solid-density plasmas created from elements and compounds

    PubMed Central

    Ciricosta, O.; Vinko, S. M.; Barbrel, B.; Rackstraw, D. S.; Preston, T. R.; Burian, T.; Chalupský, J.; Cho, B. I.; Chung, H. -K.; Dakovski, G. L.; Engelhorn, K.; Hájková, V.; Heimann, P.; Holmes, M.; Juha, L.; Krzywinski, J.; Lee, R. W.; Toleikis, S.; Turner, J. J.; Zastrau, U.; Wark, J. S.

    2016-01-01

    The effect of a dense plasma environment on the energy levels of an embedded ion is usually described in terms of the lowering of its continuum level. For strongly coupled plasmas, the phenomenon is intimately related to the equation of state; hence, an accurate treatment is crucial for most astrophysical and inertial-fusion applications, where the case of plasma mixtures is of particular interest. Here we present an experiment showing that the standard density-dependent analytical models are inadequate to describe solid-density plasmas at the temperatures studied, where the reduction of the binding energies for a given species is unaffected by the different plasma environment (ion density) in either the element or compounds of that species, and can be accurately estimated by calculations only involving the energy levels of an isolated neutral atom. The results have implications for the standard approaches to the equation of state calculations. PMID:27210741

  6. Measurements of continuum lowering in solid-density plasmas created from elements and compounds

    DOE PAGESBeta

    Ciricosta, O.; Vinko, S. M.; Barbrel, B.; Rackstraw, D. S.; Preston, T. R.; Burian, T.; Chalupský, J.; Cho, B. I.; Chung, H. -K.; Dakovski, G. L.; et al

    2016-05-23

    The effect of a dense plasma environment on the energy levels of an embedded ion is usually described in terms of the lowering of its continuum level. For strongly coupled plasmas, the phenomenon is intimately related to the equation of state; hence, an accurate treatment is crucial for most astrophysical and inertial-fusion applications, where the case of plasma mixtures is of particular interest. In this study, we present an experiment showing that the standard density-dependent analytical models are inadequate to describe solid-density plasmas at the temperatures studied, where the reduction of the binding energies for a given species is unaffectedmore » by the different plasma environment (ion density) in either the element or compounds of that species, and can be accurately estimated by calculations only involving the energy levels of an isolated neutral atom. Lastly, the results have implications for the standard approaches to the equation of state calculations.« less

  7. Orientation-dependent energy level alignment and film growth of 2,7-diocty[1]benzothieno[3,2-b]benzothiophene (C8-BTBT) on HOPG

    NASA Astrophysics Data System (ADS)

    Lyu, Lu; Niu, Dongmei; Xie, Haipeng; Cao, Ningtong; Zhang, Hong; Zhang, Yuhe; Liu, Peng; Gao, Yongli

    2016-01-01

    Combining ultraviolet photoemission spectroscopy, X-ray photoemission spectroscopy, atomic force microscopy, and X-ray diffraction measurements, we performed a systematic investigation on the correlation of energy level alignment, film growth, and molecular orientation of 2,7-diocty[1]benzothieno[3,2-b]benzothiophene (C8-BTBT) on highly oriented pyrolytic graphite. The molecules lie down in the first layer and then stand up from the second layer. The ionization potential shows a sharp decrease from the lying down region to the standing up region. When C8-BTBT molecules start standing up, unconventional energy level band-bending-like shifts are observed as the film thickness increases. These shifts are ascribed to gradual decreasing of the molecular tilt angle about the substrate normal with the increasing film thickness.

  8. Vibrational energy levels of the simplest Criegee intermediate (CH{sub 2}OO) from full-dimensional Lanczos, MCTDH, and MULTIMODE calculations

    SciTech Connect

    Yu, Hua-Gen E-mail: dawesr@mst.edu; Ndengue, Steve; Dawes, Richard E-mail: dawesr@mst.edu; Li, Jun; Guo, Hua E-mail: dawesr@mst.edu

    2015-08-28

    Accurate vibrational energy levels of the simplest Criegee intermediate (CH{sub 2}OO) were determined on a recently developed ab initio based nine-dimensional potential energy surface using three quantum mechanical methods. The first is the iterative Lanczos method using a conventional basis expansion with an exact Hamiltonian. The second and more efficient method is the multi-configurational time-dependent Hartree (MCTDH) method in which the potential energy surface is refit to conform to the sums-of-products requirement of MCTDH. Finally, the energy levels were computed with a vibrational self-consistent field/virtual configuration interaction method in MULTIMODE. The low-lying levels obtained from the three methods are found to be within a few wave numbers of each other, although some larger discrepancies exist at higher levels. The calculated vibrational levels are very well represented by an anharmonic effective Hamiltonian.

  9. Energy level alignment of self-assembled linear chains of benzenediamine on Au(111) from first principles

    DOE PAGESBeta

    Li, Guo; Rangel, Tonatiuh; Liu, Zhen -Fei; Cooper, Valentino R.; Neaton, Jeffrey B.

    2016-03-24

    Using density functional theory (DFT) with van der Waals functionals, we calculate the adsorption energetics and geometry of benzenediamine (BDA) molecules on Au(111) surfaces. Our results demonstrate that the reported self-assembled linear chain structure of BDA, stabilized via hydrogen bonds between amine groups, is energetically favored over previously-studied monomeric phases. Moreover, using a model based on many-body perturbation theory within the GW approximation, we obtain approximate self-energy corrections to the DFT highest occupied molecular orbital (HOMO) energy associated with BDA adsorbate phases. As a result, we find that, independent of coverage, the HOMO energy of the linear chain phase ismore » lower relative to the Fermi energy than that of the monomer phase, and in good agreement with values measured with ultraviolet photoelectron spectroscopy and X-ray photoelectron spectroscopy.« less

  10. Adiabatic representation in the Coulomb three-body problem in the united-atom limit: Nuclear widths of the energy levels of the muonic molecule ttµ

    NASA Astrophysics Data System (ADS)

    Melezhik, V. S.

    2016-01-01

    We study the asymptotic behavior of the wave function of the system of three Coulomb particles in the united-atom limit in the adiabatic representation of the three-body problem. This result is used to calculate the nuclear widths of muonic-molecule energy levels. We discuss features of the approach with regard to excited states of the muonic molecule ttµ with a nonzero orbital angular momentum.

  11. The energy level spacing between the ground and first excited states in InAs/GaAs quantum dots as a measure of the zero dimensionality

    NASA Astrophysics Data System (ADS)

    Lee, U. H.; Jang, Y. D.; Lee, H.; Lee, D.; Kim, J. S.; Leem, J. Y.; Noh, S. K.

    2003-04-01

    We suggest a figure of merit for the zero dimensionality, which is the most important property in quantum dots (QD). QD samples emitting at longer wavelengths are turned out to have the larger energy level spacings between the ground and first excited states. The QDs have the stronger quantum effect likely due to the taller height and are closer to an ideal zero-dimensional system.

  12. Identification of new fluorescence processes in the UV spectra of cool stars from new energy levels of Fe II and Cr II

    NASA Technical Reports Server (NTRS)

    Johansson, Sveneric; Carpenter, Kenneth G.

    1988-01-01

    Two fluorescence processes operating in atmospheres of cool stars, symbiotic stars, and the Sun are presented. Two emission lines, at 1347.03 and 1360.17 A, are identified as fluorescence lines of Cr II and Fe II. The lines are due to transitions from highly excited levels, which are populated radiatively by the hydrogen Lyman alpha line due to accidental wavelength coincidences. Three energy levels, one in Cr II and two in Fe II, are reported.

  13. Cu2ZnSnSe4 nanocrystals capped with S(2-) by ligand exchange: utilizing energy level alignment for efficiently reducing carrier rec ombination.

    PubMed

    Wang, Xia; Kou, Dong-Xing; Zhou, Wen-Hui; Zhou, Zheng-Ji; Wu, Si-Xin; Cao, Xuan

    2014-01-01

    In this work, we employed a convenient one-step synthesis method for synthesizing Cu2ZnSnSe4 (CZTSe) nanocrystals (NCs) in an excess selenium environment. This excess selenium situation enhanced the reaction of metal acetylacetonates with selenium, resulting in the burst nucleation of NCs at relatively low temperatures. The phase morphology and surface and optoelectronic properties of NCs before and after ligand exchange were discussed in depth. It was found that pure tetragonal-phase structure CZTSe NCs with approximately 1.7-eV bandgap could be synthesized. The removal of large organic molecules on CZTSe NCs after ligand exchange by S(2-) decreased the resistivity. The bandgap of the films after ligand exchange by 550°C selenization was also decreased due to better crystallinity. For potential application in CZTSe solar cells, we constructed an energy level diagram to explain the mutual effect between the absorption layer and CdS layer. Using cyclic voltammetry (CV) measurement, we found that the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy levels of CZTSe films shifted down after ligand exchange. After energy level alignment at the CdS/CZTSe interface, a type I band alignment structure was more conveniently formed after ligand exchange. This structure acted as the barrier against injection electrons from ZnO to the CZTSe layer, and recombination would subsequently be depressed. PMID:24994951

  14. Cu2ZnSnSe4 nanocrystals capped with S2− by ligand exchange: utilizing energy level alignment for efficiently reducing carrier rec ombination

    PubMed Central

    2014-01-01

    In this work, we employed a convenient one-step synthesis method for synthesizing Cu2ZnSnSe4 (CZTSe) nanocrystals (NCs) in an excess selenium environment. This excess selenium situation enhanced the reaction of metal acetylacetonates with selenium, resulting in the burst nucleation of NCs at relatively low temperatures. The phase morphology and surface and optoelectronic properties of NCs before and after ligand exchange were discussed in depth. It was found that pure tetragonal-phase structure CZTSe NCs with approximately 1.7-eV bandgap could be synthesized. The removal of large organic molecules on CZTSe NCs after ligand exchange by S2− decreased the resistivity. The bandgap of the films after ligand exchange by 550°C selenization was also decreased due to better crystallinity. For potential application in CZTSe solar cells, we constructed an energy level diagram to explain the mutual effect between the absorption layer and CdS layer. Using cyclic voltammetry (CV) measurement, we found that the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy levels of CZTSe films shifted down after ligand exchange. After energy level alignment at the CdS/CZTSe interface, a type I band alignment structure was more conveniently formed after ligand exchange. This structure acted as the barrier against injection electrons from ZnO to the CZTSe layer, and recombination would subsequently be depressed. PMID:24994951

  15. Isolated energy level in the band gap of Yb2Si2O7 identified by electron energy-loss spectroscopy

    NASA Astrophysics Data System (ADS)

    Ogawa, Takafumi; Kobayashi, Shunsuke; Wada, Masashi; Fisher, Craig A. J.; Kuwabara, Akihide; Kato, Takeharu; Yoshiya, Masato; Kitaoka, Satoshi; Moriwake, Hiroki

    2016-05-01

    We report the detection of an isolated energy level in the band gap of crystalline Yb2Si2O7 in the low-energy-loss region of its electron energy-loss (EEL) spectrum, obtained using a monochromated scanning transmission electron microscope. The experimental results are corroborated by first-principles calculations of the theoretical EEL spectrum. The calculations reveal that unoccupied Yb 4 f orbitals constitute an isolated energy level about 1 eV below the conduction band minimum (CBM), resulting in a terrace about 1 eV wide at the band edge of the EEL spectrum. In the case of Yb2O3 , no band edge terrace is present because the unoccupied f level lies just below the CBM. We also examined optical absorption properties of Yb2Si2O7 using UV-vis diffuse reflectance spectroscopy, which shows that the isolated energy level could not be detected in the band edge of the obtained absorbance spectrum. These findings demonstrate the utility of low-loss EEL spectroscopy with high energy resolution for probing semilocalized electronic features.

  16. Density functional calculations of point defects in InAs

    NASA Astrophysics Data System (ADS)

    Moussa, Jonathan; Schultz, Peter

    2013-03-01

    Standard semilocal density functionals do not generate a gap in the Kohn-Sham eigenvalues for InAs, a semiconductor with an experimental gap of 0.4 eV. Without a theoretical band gap, it becomes difficult to identify, specify, and characterize pure localized states of point defects with energy levels within the experimental band gap. The bulk band gap problem can be alleviated with screened hybrid density functionals, such as the Heyd-Scuseria-Ernzerhof (HSE) functional, that open the generalized Kohn-Sham eigenvalue gap of InAs to near the experimental value. However, even without a Kohn-Sham gap, the local moment countercharge (LMCC) method [Phys. Rev. Lett. 96, 246401 (2006)] is able to predict charge transition energy levels of localized defect states, using standard semi-local functionals. We present an LMCC-based study of standard point defects in InAs using semilocal density functionals and compare the results to HSE-based calculations to assess the validity of LMCC calculations in this situation. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. DOE's National Nuclear Security Administration under contract DE-AC04-94AL85000.

  17. Densities of stratospheric micrometeorites

    NASA Technical Reports Server (NTRS)

    Love, Stanley G.; Joswiak, David J.; Brownlee, Donald E.

    1994-01-01

    We have measured the densities of roughly 150 5- to 15-microns interplanetary dust particles (IDPs) harvested in the stratosphere. Care was taken to minimize selection bias in the sample population. Masses were determined using an absolute X-ray analysis technique with a transmission electron microscope, and volumes were found using scanning electron microscope imagery. Unmelted chondritic particles have densities ranging between 0.3 and 6.2 g/cu cm, averaging 2.0 g/cu cm. The low medium densities indicates appreciable porosity, suggesting primitive, uncompacted parent bodies for these particles. Porosities greater than 70% are rare. IDPs with densities above 3.5 g/cu cm usually contain large sulfide grains. We find no evidence of bimodality in the unmelted particle density distribution. Chondritic spherules (melted particles) have densities near 3.4 g/cu cm, consistent with previous results for stony spheurles culled from deep-sea sediments.

  18. CRDS of 17O enriched water between 5850 and 6671 cm-1: More than 1000 energy levels of H217O and HD17O newly determined

    NASA Astrophysics Data System (ADS)

    Mikhailenko, S. N.; Leshchishina, O.; Karlovets, E. V.; Mondelain, D.; Kassi, S.; Campargue, A.

    2016-07-01

    The room temperature absorption spectrum of water vapor highly enriched in 17O has been recorded by Cavity Ring Down Spectroscopy (CRDS) between 5850 and 6671 cm-1. Two series of recordings were performed with pressure values of 1.0 and 12.0 Torr. The investigated spectral region corresponds to the important 1.55 μm transparency window of the atmosphere where water absorption is very weak. The high sensitivity of the recordings (αmin ~ 5×10-11 cm-1) allows detecting lines with intensity spanning six orders of magnitude (1.4×10-30-3.6×10-24 cm/molecule at room temperature). The experimental list includes more than 10,300 lines. The assignments of water lines were performed using known experimental energy levels as well as calculated line lists based on the results of Partridge and Schwenke. More than 8500 lines were assigned to 9619 transitions of six water isotopologues (H216O, H217O, H218O, HD16O, HD17O and HD18O). All but four transitions of the 16O and 18O isotopologues were assigned using known experimental energy levels. More than half of the assigned H217O and HD17O transitions correspond to new (or corrected) upper energy levels. About 1000 new H217O transitions associated with upper states of the second triad and of the first hexad were identified. Most of the newly assigned HD17O transitions belong to the ν1+ν3 and 2ν2+ν3 bands. The assigned transitions allowed to newly determine or correct 20 highly excited rotational levels of the vibrational ground state of this isotopologue. Overall 791 and 266 energy levels are newly determined for H217O and HD17O, respectively. A few additional levels were corrected compared to literature values. The obtained experimental results are compared to the spectroscopic parameters provided by the HITRAN database and to the empirical energy levels recommended by an IUPAC task group.

  19. Average density in cosmology

    SciTech Connect

    Bonnor, W.B.

    1987-05-01

    The Einstein-Straus (1945) vacuole is here used to represent a bound cluster of galaxies embedded in a standard pressure-free cosmological model, and the average density of the cluster is compared with the density of the surrounding cosmic fluid. The two are nearly but not quite equal, and the more condensed the cluster, the greater the difference. A theoretical consequence of the discrepancy between the two densities is discussed. 25 references.

  20. Nuclear Level Densities

    SciTech Connect

    Grimes, S.M.

    2005-05-24

    Recent research in the area of nuclear level densities is reviewed. The current interest in nuclear astrophysics and in structure of nuclei off of the line of stability has led to the development of radioactive beam facilities with larger machines currently being planned. Nuclear level densities for the systems used to produce the radioactive beams influence substantially the production rates of these beams. The modification of level-density parameters near the drip lines would also affect nucleosynthesis rates and abundances.

  1. Modeling thermospheric neutral density

    NASA Astrophysics Data System (ADS)

    Qian, Liying

    Satellite drag prediction requires determination of thermospheric neutral density. The NCAR Thermosphere-Ionosphere-Electrodynamics General Circulation Model (TIEGCM) and the global-mean Thermosphere-Ionosphere-Mesosphere-Electrodynamics General Circulation Model (TIMEGCM) were used to quantify thermospheric neutral density and its variations, focusing on annual/semiannual variation, the effect of using measured solar irradiance on model calculations of solar-cycle variation, and global change in the thermosphere. Satellite drag data and the MSIS00 empirical model were utilized to compare to the TIEGCM simulations. The TIEGCM simulations indicated that eddy diffusion and its annual/semiannual variation is a mechanism for annual/semiannual density variation in the thermosphere. It was found that eddy diffusion near the turbopause can effectively influence thermospheric neutral density. Eddy diffusion, together with annual insolation variation and large-scale circulation, generated global annual/semiannual density variation observed by satellite drag. Using measured solar irradiance as solar input for the TIEGCM improved the solar-cycle dependency of the density calculation shown in F10.7 -based thermospheric empirical models. It has been found that the empirical models overestimate density at low solar activity. The TIEGCM simulations did not show such solar-cycle dependency. Using historic measurements of CO2 and F 10.7, simulations of the global-mean TIMEGCM showed that thermospheric neutral density at 400 km had an average long-term decrease of 1.7% per decade from 1970 to 2000. A forecast of density decrease for solar cycle 24 suggested that thermospheric density will decrease at 400 km from present to the end of solar cycle 24 at a rate of 2.7% per decade. Reduction in thermospheric density causes less atmospheric drag on earth-orbiting space objects. The implication of this long-term decrease of thermospheric neutral density is that it will increase the

  2. Visualization of electronic density

    DOE PAGESBeta

    Grosso, Bastien; Cooper, Valentino R.; Pine, Polina; Hashibon, Adham; Yaish, Yuval; Adler, Joan

    2015-04-22

    An atom’s volume depends on its electronic density. Although this density can only be evaluated exactly for hydrogen-like atoms, there are many excellent numerical algorithms and packages to calculate it for other materials. 3D visualization of charge density is challenging, especially when several molecular/atomic levels are intertwined in space. We explore several approaches to 3D charge density visualization, including the extension of an anaglyphic stereo visualization application based on the AViz package to larger structures such as nanotubes. We will describe motivations and potential applications of these tools for answering interesting questions about nanotube properties.

  3. Density-dependent covariant energy density functionals

    SciTech Connect

    Lalazissis, G. A.

    2012-10-20

    Relativistic nuclear energy density functionals are applied to the description of a variety of nuclear structure phenomena at and away fromstability line. Isoscalar monopole, isovector dipole and isoscalar quadrupole giant resonances are calculated using fully self-consistent relativistic quasiparticle randomphase approximation, based on the relativistic Hartree-Bogoliubovmodel. The impact of pairing correlations on the fission barriers in heavy and superheavy nuclei is examined. The role of pion in constructing desnity functionals is also investigated.

  4. Variable Density Tunnel

    NASA Technical Reports Server (NTRS)

    1931-01-01

    Variable Density Tunnel in operation. Man at far right is probably Harold J. 'Cannonball' Tuner, longtime safety officer, who started with Curtiss in the teens. This view of the Variable Density Tunnel clearly shows the layout of the Tunnel's surroundings, as well as the plumbing and power needs of the this innovative research tool.

  5. Density in a Bottle.

    ERIC Educational Resources Information Center

    Roser, Charles E.; McCluskey, Catherine L.

    1998-01-01

    Explains how the Canadian soft drink Orbitz can be used for explorations of density in the classroom. The drink has colored spheres suspended throughout that have a density close to that of the liquid. Presents a hands-on activity that can be easily done in two parts. (DDR)

  6. Bone mineral density test

    MedlinePlus

    BMD test; Bone density test; Bone densitometry; DEXA scan; DXA; Dual-energy x-ray absorptiometry; p-DEXA; Osteoporosis-BMD ... Bone density testing can be done several ways. The most common and accurate way uses a dual-energy x- ...

  7. Electronic Characterization of Defects in Narrow Gap Semiconductors-Comparison of Electronic Energy Levels and Formation Energies in Mercury Cadmium Telluride, Mercury Zinc Telluride, and Mercury Zinc Selenide

    NASA Technical Reports Server (NTRS)

    Patterson, James D.

    1996-01-01

    We have used a Green's function technique to calculate the energy levels and formation energy of deep defects in the narrow gap semiconductors mercury cadmium telluride (MCT), mercury zinc telluride (MZT) and mercury zinc selenide (MZS). The formation energy is calculated from the difference between the total energy with an impurity cluster and the total energy for the perfect crystal. Substitutional (including antisite), interstitial (self and foreign), and vacancy deep defects are considered. Relaxation effects are calculated (with molecular dynamics). By use of a pseudopotential, we generalize the ideal vacancy model so as to be able to consider relaxation for vacancies. Different charge states are considered and the charged state energy shift (as computed by a modified Haldane-Anderson model) can be twice that due to relaxation. Different charged states for vacancies were not calculated to have much effect on the formation energy. For all cases we find deep defects in the energy gap only for cation site s-like orbitals or anion site p-like orbitals, and for the substitutional case only the latter are appreciably effected by relaxation. For most cases for MCT, MZT, MZS, we consider x (the concentration of Cd or Zn) in the range appropriate for a band gap of 0.1 eV. For defect energy levels, the absolute accuracy of our results is limited, but the precision is good, and hence chemical trends are accurately predicted. For the same reason, defect formation energies are more accurately predicted than energy level position. We attempt, in Appendix B, to calculate vacancy formation energies using relatively simple chemical bonding ideas due to Harrison. However, these results are only marginally accurate for estimating vacancy binding energies. Appendix C lists all written reports and publications produced for the grant. We include abstracts and a complete paper that summarizes our work which is not yet available.

  8. Energy levels and radiative rates for transitions in B-like to F-like Xe ions (Xe L-XLVI)

    SciTech Connect

    Aggarwal, K.M. Keenan, F.P.; Lawson, K.D.

    2010-03-15

    Energy levels, radiative rates, oscillator strengths, line strengths, and lifetimes have been calculated for transitions in B-like to F-like Xe ions, Xe L-XLVI. For the calculations, a fully relativistic GRASP code has been adopted, and results are reported for all electric dipole, electric quadrupole, magnetic dipole, and magnetic quadrupole transitions among the lowest 125, 236, 272, 226, and 113 levels of Xe L, Xe XLIX, Xe XLVIII, Xe XLVII, and Xe XLVI, respectively, belonging to the n {<=} 3 configurations.

  9. Energy levels and radiative rates for transitions in B-like to F-like Kr ions (Kr XXXII-XXVIII)

    SciTech Connect

    Aggarwal, K.M. Keenan, F.P.; Lawson, K.D.

    2008-05-15

    Energy levels, radiative rates, oscillator strengths, line strengths, and lifetimes have been calculated for transitions in B-like to F-like Kr ions, Kr XXXIII-XXVIII. For the calculations, the fully relativistic GRASP code has been adopted, and results are reported for all electric dipole (E1), electric quadrupole (E2), magnetic dipole (M1), and magnetic quadrupole (M2) transitions among the lowest 125, 236, 272, 226, and 113 levels of Kr XXXII, Kr XXXI, Kr XXX, Kr XXIX, and Kr XXVIII, respectively, belonging to the n {<=} 3 configurations. Comparisons are made with earlier available theoretical and experimental results, and some discrepancies have been noted and explained.

  10. Energy level properties of 4p4d, 4p4d4f, and 4p4d configurations of the W ion

    NASA Astrophysics Data System (ADS)

    Bogdanovich, P.; Kisielius, R.

    2014-11-01

    The ab initio quasirelativistic Hartree-Fock method developed specifically for the calculation of spectroscopic parameters of heavy atoms and highly charged ions was used to derive spectral data for the multicharged tungsten ion W35+. The configuration interaction method was applied to include the electron-correlation effects. The relativistic effects were taken into account in the Breit-Pauli approximation for quasirelativistic Hartree-Fock radial orbitals. The energy level spectra, radiative lifetimes τ, and Lande g-factors have been calculated for the 4p64d3, 4p64d24f, and 4p54d4 configurations of the W35+ ion.

  11. PdO Doping Tunes Band-Gap Energy Levels as Well as Oxidative Stress Responses to a Co3O4p-Type Semiconductor in Cells and the Lung

    PubMed Central

    2014-01-01

    We demonstrate through PdO doping that creation of heterojunctions on Co3O4 nanoparticles can quantitatively adjust band-gap and Fermi energy levels to study the impact of metal oxide nanoparticle semiconductor properties on cellular redox homeostasis and hazard potential. Flame spray pyrolysis (FSP) was used to synthesize a nanoparticle library in which the gradual increase in the PdO content (0–8.9%) allowed electron transfer from Co3O4 to PdO to align Fermi energy levels across the heterojunctions. This alignment was accompanied by free hole accumulation at the Co3O4 interface and production of hydroxyl radicals. Interestingly, there was no concomitant superoxide generation, which could reflect the hole dominance of a p-type semiconductor. Although the electron flux across the heterojunctions induced upward band bending, the Ec levels of the doped particles showed energy overlap with the biological redox potential (BRP). This allows electron capture from the redox couples that maintain the BRP from −4.12 to −4.84 eV, causing disruption of cellular redox homeostasis and induction of oxidative stress. PdO/Co3O4 nanoparticles showed significant increases in cytotoxicity at 25, 50, 100, and 200 μg/mL, which was enhanced incrementally by PdO doping in BEAS-2B and RAW 264.7 cells. Oxidative stress presented as a tiered cellular response involving superoxide generation, glutathione depletion, cytokine production, and cytotoxicity in epithelial and macrophage cell lines. A progressive series of acute pro-inflammatory effects could also be seen in the lungs of animals exposed to incremental PdO-doped particles. All considered, generation of a combinatorial PdO/Co3O4 nanoparticle library with incremental heterojunction density allowed us to demonstrate the integrated role of Ev, Ec, and Ef levels in the generation of oxidant injury and inflammation by the p-type semiconductor, Co3O4. PMID:24673286

  12. PdO doping tunes band-gap energy levels as well as oxidative stress responses to a Co₃O₄ p-type semiconductor in cells and the lung.

    PubMed

    Zhang, Haiyuan; Pokhrel, Suman; Ji, Zhaoxia; Meng, Huan; Wang, Xiang; Lin, Sijie; Chang, Chong Hyun; Li, Linjiang; Li, Ruibin; Sun, Bingbing; Wang, Meiying; Liao, Yu-Pei; Liu, Rong; Xia, Tian; Mädler, Lutz; Nel, André E

    2014-04-30

    We demonstrate through PdO doping that creation of heterojunctions on Co3O4 nanoparticles can quantitatively adjust band-gap and Fermi energy levels to study the impact of metal oxide nanoparticle semiconductor properties on cellular redox homeostasis and hazard potential. Flame spray pyrolysis (FSP) was used to synthesize a nanoparticle library in which the gradual increase in the PdO content (0-8.9%) allowed electron transfer from Co3O4 to PdO to align Fermi energy levels across the heterojunctions. This alignment was accompanied by free hole accumulation at the Co3O4 interface and production of hydroxyl radicals. Interestingly, there was no concomitant superoxide generation, which could reflect the hole dominance of a p-type semiconductor. Although the electron flux across the heterojunctions induced upward band bending, the E(c) levels of the doped particles showed energy overlap with the biological redox potential (BRP). This allows electron capture from the redox couples that maintain the BRP from -4.12 to -4.84 eV, causing disruption of cellular redox homeostasis and induction of oxidative stress. PdO/Co3O4 nanoparticles showed significant increases in cytotoxicity at 25, 50, 100, and 200 μg/mL, which was enhanced incrementally by PdO doping in BEAS-2B and RAW 264.7 cells. Oxidative stress presented as a tiered cellular response involving superoxide generation, glutathione depletion, cytokine production, and cytotoxicity in epithelial and macrophage cell lines. A progressive series of acute pro-inflammatory effects could also be seen in the lungs of animals exposed to incremental PdO-doped particles. All considered, generation of a combinatorial PdO/Co3O4 nanoparticle library with incremental heterojunction density allowed us to demonstrate the integrated role of E(v), E(c), and E(f) levels in the generation of oxidant injury and inflammation by the p-type semiconductor, Co3O4. PMID:24673286

  13. Visualization of electronic density

    NASA Astrophysics Data System (ADS)

    Grosso, Bastien; Cooper, Valentino R.; Pine, Polina; Hashibon, Adham; Yaish, Yuval; Adler, Joan

    2015-10-01

    The spatial volume occupied by an atom depends on its electronic density. Although this density can only be evaluated exactly for hydrogen-like atoms, there are many excellent algorithms and packages to calculate it numerically for other materials. Three-dimensional visualization of charge density is challenging, especially when several molecular/atomic levels are intertwined in space. In this paper, we explore several approaches to this, including the extension of an anaglyphic stereo visualization application based on the AViz package for hydrogen atoms and simple molecules to larger structures such as nanotubes. We will describe motivations and potential applications of these tools for answering interesting physical questions about nanotube properties.

  14. Bone mineral density test

    MedlinePlus

    BMD test; Bone density test; Bone densitometry; DEXA scan; DXA; Dual-energy x-ray absorptiometry; p-DEXA; Osteoporosis-BMD ... need to undress. This scan is the best test to predict your risk of fractures. Peripheral DEXA ( ...

  15. Histograms and Frequency Density.

    ERIC Educational Resources Information Center

    Micromath, 2003

    2003-01-01

    Introduces exercises on histograms and frequency density. Guides pupils to Discovering Important Statistical Concepts Using Spreadsheets (DISCUSS), created at the University of Coventry. Includes curriculum points, teaching tips, activities, and internet address (http://www.coventry.ac.uk/discuss/). (KHR)

  16. Bone density scan (image)

    MedlinePlus

    ... bone the higher the risk of fractures. A bone scan, along with a patient's medical history, is a ... and whether any preventative treatment is needed. A bone density scan has the advantage of being painless and exposing ...

  17. Genetics of Bone Density

    MedlinePlus

    ... study linked 32 novel genetic regions to bone mineral density. The findings may help researchers understand why ... or treating osteoporosis. Bones are made of a mineral and protein scaffold filled with bone cells. Bone ...

  18. Nutrient Density Scores.

    ERIC Educational Resources Information Center

    Dickinson, Annette; Thompson, William T.

    1979-01-01

    Announces a nutrient density food scoring system called the Index of Nutritional Quality (INQ). It expresses the ratio between the percent RDA of a nutrient and the percent daily allowance of calories in a food. (Author/SA)

  19. Density on Dry Land.

    ERIC Educational Resources Information Center

    Libarkin, Julie C.; Crockett, Cynthia D.; Sadler, Philip M.

    2003-01-01

    Presents activities to dispel student misconceptions about density, particularly as it applies to buoyancy. Finds that misconceptions fall under three categories: (1) size; (2) shape; and (3) material. (NB)

  20. Critical Density Interaction Studies

    SciTech Connect

    Young, P; Baldis, H A; Cheung, P; Rozmus, W; Kruer, W; Wilks, S; Crowley, S; Mori, W; Hansen, C

    2001-02-14

    Experiments have been performed to study the propagation of intense laser pulses to high plasma densities. The issue of self-focusing and filamentation of the laser pulse as well as developing predictive capability of absorption processes and x-ray conversion efficiencies is important for numerous programs at the Laboratory, particularly Laser Program (Fast Ignitor and direct-drive ICF) and D&NT (radiography, high energy backlighters and laser cutting). Processes such as resonance absorption, profile modification, linear mode conversion, filamentation and stimulated Brillouin scattering can occur near the critical density and can have important effects on the coupling of laser light to solid targets. A combination of experiments have been used to study the propagation of laser light to high plasma densities and the interaction physics of intense laser pulses with solid targets. Nonparaxial fluid codes to study nonstationary behavior of filamentation and stimulated Brillouin scattering at high densities have also been developed as part of this project.

  1. Negative Ion Density Fronts

    SciTech Connect

    Igor Kaganovich

    2000-12-18

    Negative ions tend to stratify in electronegative plasmas with hot electrons (electron temperature Te much larger than ion temperature Ti, Te > Ti ). The boundary separating a plasma containing negative ions, and a plasma, without negative ions, is usually thin, so that the negative ion density falls rapidly to zero-forming a negative ion density front. We review theoretical, experimental and numerical results giving the spatio-temporal evolution of negative ion density fronts during plasma ignition, the steady state, and extinction (afterglow). During plasma ignition, negative ion fronts are the result of the break of smooth plasma density profiles during nonlinear convection. In a steady-state plasma, the fronts are boundary layers with steepening of ion density profiles due to nonlinear convection also. But during plasma extinction, the ion fronts are of a completely different nature. Negative ions diffuse freely in the plasma core (no convection), whereas the negative ion front propagates towards the chamber walls with a nearly constant velocity. The concept of fronts turns out to be very effective in analysis of plasma density profile evolution in strongly non-isothermal plasmas.

  2. Direct characterization of the energy level alignments and molecular components in an organic hetero-junction by integrated photoemission spectroscopy and reflection electron energy loss spectroscopy analysis

    NASA Astrophysics Data System (ADS)

    Yun, Dong-Jin; Shin, Weon-Ho; Bulliard, Xavier; Park, Jong Hwan; Kim, Seyun; Chung, Jae Gwan; Kim, Yongsu; Heo, Sung; Kim, Seong Heon

    2016-08-01

    A novel, direct method for the characterization of the energy level alignments at bulk-heterojunction (BHJ)/electrode interfaces on the basis of electronic spectroscopy measurements is proposed. The home-made in situ photoemission system is used to perform x-ray/ultraviolet photoemission spectroscopy (XPS/UPS), reflection electron energy loss spectroscopy (REELS) and inverse photoemission spectroscopy of organic-semiconductors (OSCs) deposited onto a Au substrate. Through this analysis system, we are able to obtain the electronic structures of a boron subphthalocyanine chloride:fullerene (SubPC:C60) BHJ and those of the separate OSC/electrode structures (SubPC/Au and C60/Au). Morphology and chemical composition analyses confirm that the original SubPC and C60 electronic structures remain unchanged in the electrodes prepared. Using this technique, we ascertain that the position and area of the nearest peak to the Fermi energy (EF = 0 eV) in the UPS (REELS) spectra of SubPC:C60 BHJ provide information on the highest occupied molecular orbital level (optical band gap) and combination ratio of the materials, respectively. Thus, extracting the adjusted spectrum from the corresponding SubPC:C60 BHJ UPS (REELS) spectrum reveals its electronic structure, equivalent to that of the C60 materials. This novel analytical approach allows complete energy-level determination for each combination ratio by separating its electronic structure information from the BHJ spectrum.

  3. Photoluminescence properties and energy levels of RE (RE = Pr, Sm, Er, Tm) in layered-CaZnOS oxysulfide

    SciTech Connect

    Zhang, Zhi-Jun; Feng, Ang; Chen, Xiang-Yang; Zhao, Jing-Tai

    2013-12-07

    RE{sup 3+} (RE = Pr, Sm, Er, Tm)-activated CaZnOS samples were prepared by a solid-state reaction method at high temperature, and their photoluminescence properties were investigated. Doping with RE{sup 3+} (RE = Pr, Sm, Er, Tm) into layered-CaZnOS resulted in typical RE{sup 3+} (RE = Pr, Sm, Er, Tm) f-f line absorptions and emissions, as well as the charge transfer band of Sm{sup 3+} at about 3.3 eV. The energy level scheme containing the position of the 4f and 5d levels of all divalent and trivalent lanthanide ions with respect to the valence and conduction bands of CaZnOS has been constructed based on the new data presented in this work, together with the data from literature on Ce{sup 3+} and Eu{sup 2+} doping in CaZnOS. The detailed energy level scheme provides a platform for interpreting the optical spectra and could be used to comment on the valence stability of the lanthanide ions in CaZnOS.

  4. Tailoring of Energy Levels in D-π-A Organic Dyes via Fluorination of Acceptor Units for Efficient Dye-Sensitized Solar Cells

    PubMed Central

    Lee, Min-Woo; Kim, Jae-Yup; Son, Hae Jung; Kim, Jin Young; Kim, BongSoo; Kim, Honggon; Lee, Doh-Kwon; Kim, Kyungkon; Lee, Duck-Hyung; Ko, Min Jae

    2015-01-01

    A molecular design is presented for tailoring the energy levels in D-π-A organic dyes through fluorination of their acceptor units, which is aimed at achieving efficient dye-sensitized solar cells (DSSCs). This is achieved by exploiting the chemical structure of common D-π-A organic dyes and incorporating one or two fluorine atoms at the ortho-positions of the cyanoacetic acid as additional acceptor units. As the number of incorporated fluorine atoms increases, the LUMO energy level of the organic dye is gradually lowered due to the electron-withdrawing effect of fluorine, which ultimately results in a gradual reduction of the HOMO-LUMO energy gap and an improvement in the spectral response. Systematic investigation of the effects of incorporating fluorine on the photovoltaic properties of DSSCs reveals an upshift in the conduction-band potential of the TiO2 electrode during impedance analysis; however, the incorporation of fluorine also results in an increased electron recombination rate, leading to a decrease in the open-circuit voltage (Voc). Despite this limitation, the conversion efficiency is gradually enhanced as the number of incorporated fluorine atoms is increased, which is attributed to the highly improved spectral response and photocurrent. PMID:25591722

  5. Energy levels, radiative rates and electron impact excitation rates for transitions in He-like Ga XXX, Ge XXXI, As XXXII, Se XXXIII and Br XXXIV

    NASA Astrophysics Data System (ADS)

    Aggarwal, Kanti M.; Keenan, Francis P.

    2013-04-01

    We report calculations of energy levels, radiative rates and electron impact excitation cross sections and rates for transitions in He-like Ga XXX, Ge XXXI, As XXXII, Se XXXIII and Br XXXIV. The grasp (general-purpose relativistic atomic structure package) is adopted for calculating energy levels and radiative rates. For determining the collision strengths, and subsequently the excitation rates, the Dirac atomic R-matrix code (darc) is used. Oscillator strengths, radiative rates and line strengths are reported for all E1, E2, M1 and M2 transitions among the lowest 49 levels of each ion. Additionally, theoretical lifetimes are provided for all 49 levels of the above five ions. Collision strengths are averaged over a Maxwellian velocity distribution and the effective collision strengths obtained listed over a wide temperature range up to 108 K. Comparisons are made with similar data obtained using the flexible atomic code (fac) to highlight the importance of resonances, included in calculations with darc, in the determination of effective collision strengths. Discrepancies between the collision strengths from darc and fac, particularly for some forbidden transitions, are also discussed. Finally, discrepancies between the present results for effective collision strengths with the darc code and earlier semi-relativistic R-matrix data are noted over a wide range of electron temperatures for many transitions in all ions.

  6. Direct characterization of the energy level alignments and molecular components in an organic hetero-junction by integrated photoemission spectroscopy and reflection electron energy loss spectroscopy analysis.

    PubMed

    Yun, Dong-Jin; Shin, Weon-Ho; Bulliard, Xavier; Park, Jong Hwan; Kim, Seyun; Chung, Jae Gwan; Kim, Yongsu; Heo, Sung; Kim, Seong Heon

    2016-08-26

    A novel, direct method for the characterization of the energy level alignments at bulk-heterojunction (BHJ)/electrode interfaces on the basis of electronic spectroscopy measurements is proposed. The home-made in situ photoemission system is used to perform x-ray/ultraviolet photoemission spectroscopy (XPS/UPS), reflection electron energy loss spectroscopy (REELS) and inverse photoemission spectroscopy of organic-semiconductors (OSCs) deposited onto a Au substrate. Through this analysis system, we are able to obtain the electronic structures of a boron subphthalocyanine chloride:fullerene (SubPC:C60) BHJ and those of the separate OSC/electrode structures (SubPC/Au and C60/Au). Morphology and chemical composition analyses confirm that the original SubPC and C60 electronic structures remain unchanged in the electrodes prepared. Using this technique, we ascertain that the position and area of the nearest peak to the Fermi energy (EF = 0 eV) in the UPS (REELS) spectra of SubPC:C60 BHJ provide information on the highest occupied molecular orbital level (optical band gap) and combination ratio of the materials, respectively. Thus, extracting the adjusted spectrum from the corresponding SubPC:C60 BHJ UPS (REELS) spectrum reveals its electronic structure, equivalent to that of the C60 materials. This novel analytical approach allows complete energy-level determination for each combination ratio by separating its electronic structure information from the BHJ spectrum. PMID:27420635

  7. Energy levels, transition rates, oscillator strengths and lifetimes in Ne-like, Ni-like, and Cu-like uranium ions

    NASA Astrophysics Data System (ADS)

    Bari, M. A.; Nazir, R. T.; Nasim, M. H.; Duan, B.; Azeem, M.; Shabbir Naz, G.; Salahuddin, M.

    2015-01-01

    We present the fine-structure energy levels, wavelengths, oscillator strengths, transition energies, and transition rates of optically allowed inner-shell transitions of Ne-, Ni-, and Cu-like uranium ions by using the multiconfiguration Dirac-Fock method with the fully relativistic GRASP2 code (partly improved by us). In order to compare these results, we have performed other independent calculations with a fully relativistic Flexible Atomic Code (FAC). We have determined extensive configuration interaction wavefunctions to calculate the level energies of the inner-shell excited states of these three uranium ionic states. Overall, our calculated energy levels, wavelengths, transition rates, and oscillator strengths within the levels of selected configurations show better agreement with the available experimental and other theoretical results. Furthermore, we report radiative lifetimes of all the excited states of these three uranium ions. We also present many unpublished data about energy values, wavelengths, transitions rates, and oscillator strengths for inner-shell transitions. We believe that our calculated inner shell transition energies are of interest for the analysis of uranium x-ray spectra.

  8. Hot water emission spectra: Rotational energy levels of the (0 0 0) and (0 1 0) states of HD17O

    NASA Astrophysics Data System (ADS)

    Mellau, Georg Ch.; Mikhailenko, Semen N.; Tyuterev, Vladimir G.

    2015-02-01

    The rotational transitions of the HD17O water isotopologue have been assigned in a high temperature emission spectrum between 320 and 520 cm-1 of water vapor enriched by deuterium and 17O. We assigned 169 emission lines to 189 partly overlapping transitions of pure rotational and the ν2-ν2 rotational bands. A new extended set of 390 rotational energy levels for the (0 0 0) and (0 1 0) vibration states of HD17O up to J = 17 and Ka = 13 was obtained by combination of the new line transitions with those reported in previous studies. We constructed an effective rotational Hamiltonian based on the generation function approach. For this Hamiltonian the deviation between calculated and measured eigenenergies is in the order of 0.001 cm-1. We report a new calculated linelist based on our new energy level list. Our linelist supersedes the IUPAC linelist for the HD17O water isotopologue as it is based on a substantially extended set of accurate transition wavenumbers.

  9. In Pursuit of the Far-Infrared Spectrum of Cyanogen Iso-Thiocyanate Ncncs, Under the Influence of the Energy Level Dislocation due to Quantum Monodromy

    NASA Astrophysics Data System (ADS)

    Winnewisser, Manfred; Winnewisser, Brenda P.; Medvedev, Ivan R.; De Lucia, Frank, C.; Ross, Stephen C.; Koput, Jacek

    2010-06-01

    Quantum Monodromy has a strong impact on the ro-vibrational energy levels of chain molecules whose bending potential energy function has the form of the bottom of a champagne bottle (i.e. with a hump or punt) around the linear configuration. NCNCS is a particularly good example of such a molecule and clearly exhibits a distinctive monodromy-induced dislocation of the energy level pattern at the top of the potential energy hump. The generalized semi-rigid bender (GSRB) wave functions are used to show that the expectation values of any physical quantity which varies with the large amplitude bending coordinate will also have monodromy-induced dislocations. This includes the electric dipole moment components. High level ab initio calculations not only provided the molecular equilibrium structure of NCNCS, but also the electric dipole moment components μa and μb as functions of the large-amplitude bending coordinate. The calculated expectation values of these quantities indicate large ro-vibrational transition moments that will be discussed in pursuit of possible far-infrared bands. To our knowledge there is no NCNCS infrared spectrum reported in the literature. B. P. Winnewisser, M. Winnewisser, I. R. Medvedev, F. C. De Lucia, S. C. Ross and J. Koput, Phys. Chem. Chem. Phys., 2010, DOI:10.1039/B922023B.

  10. Energy levels, oscillator strengths and transition probabilities for Si-like P II, S III, Cl IV, Ar V and K VI

    SciTech Connect

    Abou El-Maaref, A.; Uosif, M.A.M.; Allam, S.H.; El-Sherbini, Th.M.

    2012-07-15

    Fine-structure calculations of energy levels, oscillator strengths, and transition probabilities for transitions among the terms belonging to 3s{sup 2}3p{sup 2}, 3s3p{sup 3}, 3s{sup 2}3p3d, 3s{sup 2}3p4s, 3s{sup 2}3p4p, 3s{sup 2}3p4d, 3s{sup 2}3p5s and 3s{sup 2}3p5p configurations of silicon-like ions P II, S III, Cl IV, Ar V and K VI have been calculated using configuration-interaction version 3 (CIV3). We compared our data with the available experimental data and other theoretical calculations. Most of our calculations of energy levels and oscillator strengths (in length form) show good agreement with both experimental and theoretical data. Lifetimes of the excited levels are also given.

  11. Improved low-lying energy levels determined from solar coronal forbidden and spin-forbidden lines in the 500-1500 A range

    SciTech Connect

    Feldman, U.; Doschek, G.A. . E-mail: george.doschek@nrl.navy.mil

    2007-09-15

    We list observed parity-forbidden and spin-forbidden lines in the 500-1600 A range emitted by solar coronal plasmas and derive improved energy levels from their wavelengths. The lines, emitted by astrophysical abundant elements, belong to transitions within the ground configurations of the type ns{sup 2} np {sup k}, for n = 2, 3 and k = 0-5, and between the lowest term of the first excited configuration 2s2p {sup k+1} and the 2s{sup 2}2p {sup k} ground configurations for k = 0, 1, 2. For each line we give the newly measured wavelength, and the measured or predicted wavelength from the NIST Atomic Spectra Database (ASD) (which except for a few cases includes the previously reported compilation of Kaufman and Sugar [J. Phys. Chem. Ref. Data 15 (1986) 321]), and the values of the transition probability taken from the ASD and CHIANTI database. The list contains measured wavelengths of 136 lines of which over 100 were not available for the Kaufman and Sugar compilation. In addition we provide energy levels that were derived from the reported lines.

  12. Energy levels, wavelengths, and transition rates of multipole transitions (E1, E2, M1, M2) in Au{sup 67+} and Au{sup 66+} ions

    SciTech Connect

    Hamasha, Safeia

    2013-11-15

    The fully relativistic configuration interaction method of the FAC code is used to calculate atomic data for multipole transitions in Mg-like Au (Au{sup 67+}) and Al-like Au (Au{sup 66+}) ions. Generated atomic data are important in the modeling of M-shell spectra for heavy Au ions and Au plasma diagnostics. Energy levels, oscillator strengths and transition rates are calculated for electric-dipole (E1), electric quadrupole (E2), magnetic dipole (M1), and magnetic quadrupole (M2) for transitions between excited and ground states 3l−nl{sup ′}, such that n=4,5,6,7. The local central potential is derived using the Dirac–Fock–Slater method. Correlation effects to all orders are considered by the configuration interaction expansion. All relativistic effects are included in the calculations. Calculated energy levels are compared against published values that were calculated using the multi-reference many body perturbation theory, which includes higher order QED effects. Favorable agreement was observed, with less than 0.15% difference.

  13. Modelling ionospheric density structures

    NASA Technical Reports Server (NTRS)

    Schunk, R. W.; Sojka, J. J.

    1989-01-01

    Large-scale density structures are a common feature in the high-latitude ionsphere. The structures were observed in the dayside cusp, polar cap, and nocturnal auroral region over a range of altitudes, including the E-region, F-region and topside ionosphere. The origins, lifetimes and transport characteristics of large-scale density structures were studied with the aid of a three-dimensional, time-dependent ionospheric model. Blob creation due to particle precipitation, the effect that structured electric fields have on the ionosphere, and the lifetimes and transport characteristics of density structures for different seasonal, solar cycle, and interplanetary magnetic field (IMF) conditions were studied. The main conclusions drawn are: (1) the observed precipitation energy fluxes are sufficient for blob creation if the plasma is exposed to the precipitation for 5 to 10 minutes; (2) structured electric fields produce structured electron densities, ion temperatures, and ion composition; (3) the lifetime of an F-region density structure depends on several factors, including the initial location where it was formed, the magnitude of the perturbation, season, solar cycle and IMF; and (4) depending on the IMF, horizontal plasma convection can cause an initial structure to break up into multiple structures of various sizes, remain as a single distorted structure, or become stretched into elongated segments.

  14. Nuclear Level Densities

    SciTech Connect

    Grimes, S. M.; Voinov, A.

    2009-01-28

    A summary of some recent level density research is presented. Although the subject is an old one, it is argued that a number of unanswered questions remain. These include uncertainties in related quantities such as the parity ratio and the spin cutoff parameter, which are needed to deduce level density parameters from resonance counting for low energy neutrons. Additional points of interest are the extent to which the low energy region shows constant temperature rather than Fermi gas energy dependence, whether the region below the neutron binding energy shows significant structure and whether the level density for fixed A shows a drop for neutron-rich and proton-rich nuclei compared to nuclei on the valley of stability.

  15. Electronic Energy-Level Structures, Optical Line Strengths, and Correlation Crystal-Field Interactions in NEODYMIUM(3+) and ERBIUM(3+) Crystalline Compounds.

    NASA Astrophysics Data System (ADS)

    Quagliano, John Romolo

    Energy-level state structures of Nd^ {3+} (4f^3) and Er^{3+} (4f^ {11}) electronic configurations were analyzed in a total of 13 distinct chemical systems. The 13 systems included seven crystalline hosts that contain Nd ^{3+} ions (four garnets, one nonahydrate, one hexachloride, and one hexabromide), and six that contain Er^{3+} ions (three garnets, one oxalate-bioxalate, one hexachloride, and one hexabromide). Single crystal absorption spectra (polarized and unpolarized) and optical intensity data have been acquired for neat (rm Nd(H_2O)_9) (CF _3rm SO_3)_3 at cryogenic temperatures over the UV to near-IR energy range. Single crystal polarized orthoaxial absorption, excitation, and emission experiments were performed on Er^{3+}-doped CsCdBr _3. Model Hamiltonians were developed and used to calculate lanthanide 4f^{rm N } electronic structures. These Hamiltonians were constructed and parametrized to represent both atomic and crystal-field interactions in various host materials. A Hamiltonian with atomic and first-order crystal-field operators gave a very good initial description of the energy-level structures, and a second-order correlation crystal-field (CCF) refinement produced excellent results for some multiplet manifolds that are not well characterized by the first -order (one-particle) crystal-field interactions alone. The ^2rm H(2)_{11/2} , ^2{F}(2)_ {5/2}, and ^2rm F(2) _{7/2} multiplet manifolds of Nd ^{3+} and the ^2rm H(2)_{9/2}, ^2H(2) _{11/2}, and ^4 rm G_{11/2} multiplet manifolds of Er^{3+} were markedly improved after a maximum of three CCF operators were added to the Hamiltonian. The studies showed that since the Nd^{3+} and Er ^{3+} ions share the same SLJ (Russell -Saunders) basis of atomic states, then their respective energy-level structures are sensitive to the same CCF operators. The magnitudes of the CCF interactions were found to be typically 10% of the first-order one-particle crystal-field interactions. The present work establishes a new

  16. Density Equalizing Map Projections

    SciTech Connect

    Close, E. R.; Merrill, D. W.; Holmes, H. H.

    1995-07-01

    A geographic map is mathematically transformed so that the subareas of the map are proportional to a given quantity such as population. In other words, population density is equalized over the entire map. The transformed map can be used as a display tool, or it can be statistically analyzed. For example, cases of disease plotted on the transformed map should be uniformly distributed at random, if disease rates are everywhere equal. Geographic clusters of disease can be readily identified, and their statistical significance determined, on a density equalized map.

  17. Density Equalizing Map Projections

    Energy Science and Technology Software Center (ESTSC)

    1995-07-01

    A geographic map is mathematically transformed so that the subareas of the map are proportional to a given quantity such as population. In other words, population density is equalized over the entire map. The transformed map can be used as a display tool, or it can be statistically analyzed. For example, cases of disease plotted on the transformed map should be uniformly distributed at random, if disease rates are everywhere equal. Geographic clusters of diseasemore » can be readily identified, and their statistical significance determined, on a density equalized map.« less

  18. Low density solid ozone

    SciTech Connect

    Teolis, B. D.; Fama, M.; Baragiola, R. A.

    2007-08-21

    We report a very low density ({approx}0.5 g/cm{sup 3}) structure of solid ozone. It is produced by irradiation of solid oxygen with 100 keV protons at 20 K followed by heating to sublime unconverted oxygen. Upon heating to 47 K the porous ozone compacts to a density of {approx}1.6 g/cm{sup 3} and crystallizes. We use a detailed analysis of the main infrared absorption band of the porous ozone to interpret previous research, where solid oxygen was irradiated by UV light and keV electrons.

  19. Crystal Field Parameters and Energy Levels Calculations for Fe{sup 3+}:ZnGa{sub 2}O{sub 4}

    SciTech Connect

    Vaida, M.; Brik, M. G.; Avram, N. M.

    2010-08-04

    In this paper, we present a theoretical study of the energy levels structure for the zinc gallate normal spinel, ZnGa{sub 2}O{sub 4}, doped with Fe{sup 3+}(3d{sup 5} configuration) ions. The calculations have been performed in the framework of the exchange charge model (ECM) of the crystal field. After calculating the CFPs, based on the geometrical structure of the host matrix, the crystal field Hamiltonian was diagonalized in the space spanned by the wave functions of all 16 LS terms of the 3d{sup 5} electron configurations. The Racah parameters B, C and G parameter of the exchange charge model have been estimated. The results of the theoretical calculations are in satisfactory agreement with the experimental data.

  20. Luminescence and Energy Levels of Mn2+ in LnMB5O10 (Ln=La, Gd and Y; M=Mg, Zn and Cd)

    NASA Astrophysics Data System (ADS)

    Jagannathan, R.; Manoharan, S. P.; Rao, R. P.; Kutty, T. R. N.

    1990-10-01

    Luminescence of Bi3+ or/and Mn2+ in LnMB5O10 system of phosphor has been studied. Bi3+ in LnMB5O10 leads to two types of emissions, viz. emission due to (i) Bi3+ isolated centres and (ii) Bi3+ clusters. In LaMB5O10, Bi3+ emission can cover longer distances (25 Å) for resonant transfer. In LaMgB5O10, replacement of Mg by Cd or Zn leads to considerable enhancement in Mn2+ emission intensity. In the case of GdMB5O10 system, this substitution leads to significant increase in the Gd3+→Mn2+ energy transfer rate. Energy levels of Mn2+ in LaMB5O10 and crystal field parameters (for the case of cubic field) have been calculated and the results based on these are discussed.

  1. Electron capture and positron decay of /sup 206/Fr and /sup 208/Fr and the energy levels of /sup 206/Rn and /sup 208/Rn

    SciTech Connect

    Ritchie, B.G.; Avignone, F.T. III; Carter, H.K.; Mlekodaj, R.L.; Spejewski, E.H.

    1981-04-01

    The isotopes /sup 206/Fr and /sup 208/Fr were produced by the reactions Ir(/sup 20/Ne,xn)/sup 206,208/Fr and mass separated on-line. The electron-capture and positron decays to /sup 206/Rn and /sup 208/Rn were studied by collecting ..gamma.. ray and internal conversion electron singles spectra as a function of decay time as well as ..gamma..-..gamma.., ..gamma..-e/sup -/, and ..gamma..-x ray coincidence spectra. The energies and many of the spins were determined for 18 excited, even parity states in /sup 208/Rn and for 10 excited, even parity states in /sup 206/Rn. These nuclei appear to be excellent candidates for interpretation in terms of a weak coupling shell model. The energy levels were also compared to the predictions of the interacting boson approximation model.

  2. Density in Liquids.

    ERIC Educational Resources Information Center

    Nesin, Gert; Barrow, Lloyd H.

    1984-01-01

    Describes a fourth-grade unit on density which introduces a concept useful in the study of chemistry and procedures appropriate to the chemistry laboratory. The hands-on activities, which use simple equipment and household substances, are at the level of thinking Piaget describes as concrete operational. (BC)

  3. Multiple density layered insulator

    DOEpatents

    Alger, T.W.

    1994-09-06

    A multiple density layered insulator for use with a laser is disclosed which provides at least two different insulation materials for a laser discharge tube, where the two insulation materials have different thermoconductivities. The multiple layer insulation materials provide for improved thermoconductivity capability for improved laser operation. 4 figs.

  4. Multiple density layered insulator

    DOEpatents

    Alger, Terry W.

    1994-01-01

    A multiple density layered insulator for use with a laser is disclosed wh provides at least two different insulation materials for a laser discharge tube, where the two insulation materials have different thermoconductivities. The multiple layer insulation materials provide for improved thermoconductivity capability for improved laser operation.

  5. Material and Optical Densities

    ERIC Educational Resources Information Center

    Gluck, Paul

    2007-01-01

    The bending of a laser beam in a medium with a density and refractive index gradient in the same direction has been described previously. When a transparent container is half filled with a salt or sugar solution and an equal amount of water is floated on top of it, then diffusion will create a concentration gradient from top to bottom. A laser…

  6. Energy-level calculations for the 5f 26d 1 configuration of U 3+ in Cs 2NaYCl 6 single crystals

    NASA Astrophysics Data System (ADS)

    Karbowiak, M.

    2005-07-01

    Energy levels and the 5f 3 → 5f 26d(t 2g) 1 transition intensities of U 3+ in Cs 2NaYCl 6 were calculated using a theoretical model for nf N energy levels extended for interactions related with the presence of d-electron, proposed by Reid et al. [M.F. Reid, L. van Pieterson, R.T. Wegh, A. Meijerink, Phys. Rev. B 62 (2000) 14744]. The Fk(fd) and Gj(fd) parameters for f-d Coulomb interactions, the ζ(dd) spin-orbit interactions parameter for 6d electron as well as B04(ff)andB06(ff) crystal-field parameters for 5f 2 core electrons were adjusted, and a very good agreement between calculated and experimental spectrum has been achieved. The F2(fd), G1(fd) and ζ(dd) parameters were reduced to 37.5%, 45.3% and 77.2% of the ab initio calculated free-ion values, respectively. The values of Bqk(ff) parameters determined for 5f 26d 1 configuration are closer to those of 5f 2 configuration of U 4+ than 5f 3 configuration of U 3+. The results of calculations performed in the frame of the semi-empirical Hamiltonian model are in a very good accordance with those of ab initio theoretical analysis, reported by Seijo and Barandiarán [L. Seijo, Z. Barandiarán, J. Chem. Phys. 118 (2003) 5335].

  7. Photodetachment of gaseous multiply charged anions, copper phthalocyanine tetrasulfonate tetraanion: Tuning molecular electronic energy levels by charging and negative electron binding

    SciTech Connect

    Wang, X.B.; Ferris, K.; Wang, L.S.

    2000-01-13

    The authors report photodetachment photoelectron spectroscopy (PES) of gaseous copper phthalocyanine (CuPc) tetrasulfonate quadruply charged anions, [CuPc(SO{sub 3}){sub 4}]{sup 4{minus}}, and its monoprotonated and -sodiumated triply charged anions, [CuPc(SO{sub 3}){sub 4}H]{sup 3{minus}} and [CuPc(SO{sub 3}){sub 4}Na]{sup 3{minus}}. The [CuPc(SO{sub 3}){sub 4}]{sup 4{minus}} tetraanion was found to possess a negative electron binding energy of {minus}0.9 eV, whereas the trianions have binding energies of 1.0 and 1.2 eV for the sodiumated and protonated species, respectively. The PES spectral features of the three multiply charged anions were observed to be similar to that of the parent CuPc neutral molecule, except that the anions have lower binding energies due to the presence of the negative charges ({minus}SO{sub 3}{sup {minus}}). The data thus suggested a stepwise tuning of the molecular electronic energy levels of the CuPc molecule through charging, wherein the molecular orbital energies of the parent molecule were systematically pushed up by the negative charges. The authors further carried out semiempirical calculations, which provided insight into the nature of the localized charges on the peripheral {minus}SO{sub 3}{sup {minus}} groups and the intramolecular electrostatic interactions in the multiply charged anions and confirmed the interpretation of the stepwise tuning of molecular energy levels by charging. Photon energy-dependent studies revealed the effects of the repulsive Coulomb barriers on the photodetachment PES spectra of the multiply charged anions. The barrier heights were estimated to be about 3.5 and 2.5 eV for the tetra- and trianions, respectively. The authors also observed excited states for the multiply charged anions and resonant tunneling through the repulsive Coulomb barriers via the excited states.

  8. Energy-level matching of Fe(III) ions grafted at surface and doped in bulk for efficient visible-light photocatalysts.

    PubMed

    Liu, Min; Qiu, Xiaoqing; Miyauchi, Masahiro; Hashimoto, Kazuhito

    2013-07-10

    Photocatalytic reaction rate (R) is determined by the multiplication of light absorption capability (α) and quantum efficiency (QE); however, these two parameters generally have trade-off relations. Thus, increasing α without decreasing QE remains a challenging issue for developing efficient photocatalysts with high R. Herein, using Fe(III) ions grafted Fe(III) doped TiO2 as a model system, we present a novel method for developing visible-light photocatalysts with efficient R, utilizing the concept of energy level matching between surface-grafted Fe(III) ions as co-catalysts and bulk-doped Fe(III) ions as visible-light absorbers. Photogenerated electrons in the doped Fe(III) states under visible-light efficiently transfer to the surface grafted Fe(III) ions co-catalysts, as the doped Fe(III) ions in bulk produced energy levels below the conduction band of TiO2, which match well with the potential of Fe(3+)/Fe(2+) redox couple in the surface grafted Fe(III) ions. Electrons in the surface grafted Fe(III) ions efficiently cause multielectron reduction of adsorbed oxygen molecules to achieve high QE value. Consequently, the present Fe(III)-FexTi1-xO2 nanocomposites exhibited the highest visible-light R among the previously reported photocatalysts for decomposition of gaseous organic compounds. The high R can proceed even under commercial white-light emission diode irradiation and is very stable for long-term use, making it practically useful. Further, this efficient method could be applied in other wide-band gap semiconductors, including ZnO or SrTiO3, and may be potentially applicable for other photocatalysis systems, such as water splitting, CO2 reduction, NOx removal, and dye decomposition. Thus, this method represents a strategic approach to develop new visible-light active photocatalysts for practical uses. PMID:23768256

  9. Effect of protein and energy levels in sweet sorghum bagasse leaf residue-based diets on the performance of growing Deccani lambs.

    PubMed

    Yerradoddi, Ramana Reddy; Khan, Arif Ali; Mallampalli, Saibutcha Rao; Devulapalli, Ravi; Kodukula, Prasad; Blümmel, Michael

    2015-04-01

    Sweet sorghum bagasse with leaf residue (SSBLR) based complete diets with high or low protein and high- or low-energy levels were evaluated in a 60-day growth trial using growing sheep. Twenty-eight Deccani ram lambs were divided into four groups (16.0 ± 0.59 kg) of seven each and fed low-protein high-/low-energy and high-protein high-/low-energy diets ad lib. Average daily gain (g; P < 0.05) and feed efficiency (P < 0.01) were significantly higher in lambs fed high energy than those with low-energy diets, and cost per kg gain ($) was significantly lower (P < 0.05) in low protein than high-protein diets. Dry matter intake (DMI) (g/day) was not significantly affected either by protein or energy level in the diet, but dry matter (DM), organic matter (OM), protein, and neutral detergent fiber (NDF) digestibilities were higher significantly (P < 0.01) in high protein/energy diets than low protein/energy diets. Crude protein (CP) intake (g/day) was significantly (P < 0.001) higher in lambs fed high protein than low-protein diets. However, N balance (g/day) was significantly (P < 0.001) higher in lambs fed low protein than high-protein diets. It is concluded that feeding of SSBLR-based diet with low protein (CP 12.9 %) and high energy (9.4 MJ metabolizable energy (ME)/kg DM) was recommended for better performance, nitrogen retention, and returns from growing Deccani ram lambs. PMID:25757879

  10. Extension of a Kinetic Approach to Chemical Reactions to Electronic Energy Levels and Reactions Involving Charged Species with Application to DSMC Simulations

    NASA Technical Reports Server (NTRS)

    Liechty, Derek S.

    2014-01-01

    The ability to compute rarefied, ionized hypersonic flows is becoming more important as missions such as Earth reentry, landing high mass payloads on Mars, and the exploration of the outer planets and their satellites are being considered. Recently introduced molecular-level chemistry models that predict equilibrium and nonequilibrium reaction rates using only kinetic theory and fundamental molecular properties are extended in the current work to include electronic energy level transitions and reactions involving charged particles. These extensions are shown to agree favorably with reported transition and reaction rates from the literature for near-equilibrium conditions. Also, the extensions are applied to the second flight of the Project FIRE flight experiment at 1634 seconds with a Knudsen number of 0.001 at an altitude of 76.4 km. In order to accomplish this, NASA's direct simulation Monte Carlo code DAC was rewritten to include the ability to simulate charge-neutral ionized flows, take advantage of the recently introduced chemistry model, and to include the extensions presented in this work. The 1634 second data point was chosen for comparisons to be made in order to include a CFD solution. The Knudsen number at this point in time is such that the DSMC simulations are still tractable and the CFD computations are at the edge of what is considered valid because, although near-transitional, the flow is still considered to be continuum. It is shown that the inclusion of electronic energy levels in the DSMC simulation is necessary for flows of this nature and is required for comparison to the CFD solution. The flow field solutions are also post-processed by the nonequilibrium radiation code HARA to compute the radiative portion.

  11. Extension of a Kinetic Approach to Chemical Reactions to Electronic Energy Levels and Reactions Involving Charged Species With Application to DSMC Simulations

    NASA Technical Reports Server (NTRS)

    Liechty, Derek S.

    2013-01-01

    The ability to compute rarefied, ionized hypersonic flows is becoming more important as missions such as Earth reentry, landing high mass payloads on Mars, and the exploration of the outer planets and their satellites are being considered. Recently introduced molecular-level chemistry models that predict equilibrium and nonequilibrium reaction rates using only kinetic theory and fundamental molecular properties are extended in the current work to include electronic energy level transitions and reactions involving charged particles. These extensions are shown to agree favorably with reported transition and reaction rates from the literature for nearequilibrium conditions. Also, the extensions are applied to the second flight of the Project FIRE flight experiment at 1634 seconds with a Knudsen number of 0.001 at an altitude of 76.4 km. In order to accomplish this, NASA's direct simulation Monte Carlo code DAC was rewritten to include the ability to simulate charge-neutral ionized flows, take advantage of the recently introduced chemistry model, and to include the extensions presented in this work. The 1634 second data point was chosen for comparisons to be made in order to include a CFD solution. The Knudsen number at this point in time is such that the DSMC simulations are still tractable and the CFD computations are at the edge of what is considered valid because, although near-transitional, the flow is still considered to be continuum. It is shown that the inclusion of electronic energy levels in the DSMC simulation is necessary for flows of this nature and is required for comparison to the CFD solution. The flow field solutions are also post-processed by the nonequilibrium radiation code HARA to compute the radiative portion of the heating and is then compared to the total heating measured in flight.

  12. Insight into the roles of structures and energy levels of mono- and bis-β-diketones on sensitizing Nd(iii) NIR-luminescence.

    PubMed

    Li, Bing; Li, Hongfeng; Chen, Peng; Sun, Wenbin; Wang, Cheng; Gao, Ting; Yan, Pengfei

    2016-07-28

    Three neodymium complexes Nd(TTA)3(DMSO)2 (1, TTA = 2-thenoyltrifluoroacetone), Nd2(BDT)3(DMSO)6 (2, BDT = bis(4,4,4-trifluoro-1,3-dioxobutyl)thiophene) and Nd2(BTT)3(DMSO)4 (3, BTT = bis(4,4,4-trifluoro-1,3-dioxobutyl)(2,2'-bithiophene)) constructed from three thiophene-based β-diketonate ligands, were prepared for the purpose of building the relationships between the structures, energy levels of the complexes and NIR luminescence properties of Nd(iii) ions. X-ray crystallographical analysis reveals that complex 1 is a mononuclear structure, the central Nd(iii) ion is coordinated by eight oxygen atoms from three mono-β-diketones (TTA) and two DMSO, whereas, complexes 2 and 3 adopt triple-stranded dinuclear structures, in which the two Nd(iii) ions are wrapped by three bis-β-diketones, the central Nd(iii) ions are nine and eight coordinated by oxygen atoms from ligands and the coordinated DMSO molecules. The photophysical properties related to the electronic transition are characterized by the absorbance spectra, the excitation spectra, the phosphorescence spectra, the emission spectra, the emission quantum yields, and the emission lifetimes. The luminescence quantum yields experiment reveals that the dinuclear complexes (0.49% and 0.33% for 2 and 3) show higher luminescence efficiencies compared to the mononuclear complex 1 (0.22%). This enhancement is mainly attributed to their binuclear structures, which effectively represses the nonradiative transition caused by high-energy oscillators in ligands and/or solvents. On the other hand, the energy level matching also plays an important role in this enhancement. PMID:27346610

  13. Partition density functional theory

    NASA Astrophysics Data System (ADS)

    Nafziger, Jonathan

    Partition density functional theory (PDFT) is a method for dividing a molecular electronic structure calculation into fragment calculations. The molecular density and energy corresponding to Kohn Sham density-functional theory (KS-DFT) may be exactly recovered from these fragments. Each fragment acts as an isolated system except for the influence of a global one-body 'partition' potential which deforms the fragment densities. In this work, the developments of PDFT are put into the context of other fragment-based density functional methods. We developed three numerical implementations of PDFT: One within the NWChem computational chemistry package using basis sets, and the other two developed from scratch using real-space grids. It is shown that all three of these programs can exactly reproduce a KS-DFT calculation via fragment calculations. The first of our in-house codes handles non-interacting electrons in arbitrary one-dimensional potentials with any number of fragments. This code is used to explore how the exact partition potential changes for different partitionings of the same system and also to study features which determine which systems yield non-integer PDFT occupations and which systems are locked into integer PDFT occupations. The second in-house code, CADMium, performs real-space calculations of diatomic molecules. Features of the exact partition potential are studied for a variety of cases and an analytical formula determining singularities in the partition potential is derived. We introduce an approximation for the non-additive kinetic energy and show how this quantity can be computed exactly. Finally a PDFT functional is developed to address the issues of static correlation and delocalization errors in approximations within DFT. The functional is applied to the dissociation of H2 + and H2.

  14. [Low density lipoprotein apheresis].

    PubMed

    Zaliūnas, Remigijus; Slapikas, Rimvydas; Gustiene, Olivija; Siurkus, Jonas; Vaitkus, Eduardas

    2003-01-01

    Increased blood cholesterol concentration is one of the main factors in ischemic heart disease, development of which is determined by atherosclerotic changes in coronary vessels. Diet and treatment with 3-hydroxi-3-metilglutaril coenzyme A (HMG-CoA) reductase inhibitors helps to reduce low density lipoprotein cholesterol (LDL-Ch) blood concentration up to recommended level of 3.0 mmol/l in most patients but in some patients particularly with familial dyslipidemias cholesterol concentration remains increased even after treatment with maximal doses of lipid-regulating agents or their combinations. The most frequently used mechanical methods of cholesterol removal from blood include the procedures of extracorporeal apheresis. Low density lipoprotein (LDL) apheresis not only significantly reduces the blood concentrations of total cholesterol (TCh), and LDL-Ch, lipoprotein (a) (Lp(a) and fibrinogen but also stops the progression of atherosclerosis in coronary vessels. PMID:14704503

  15. Extracting primordial density fluctuations

    PubMed

    Gawiser; Silk

    1998-05-29

    The combination of detections of anisotropy in cosmic microwave background radiation and observations of the large-scale distribution of galaxies probes the primordial density fluctuations of the universe on spatial scales varying by three orders of magnitude. These data are found to be inconsistent with the predictions of several popular cosmological models. Agreement between the data and the cold + hot dark matter model, however, suggests that a significant fraction of the matter in the universe may consist of massive neutrinos. PMID:9603724

  16. High power density targets

    NASA Astrophysics Data System (ADS)

    Pellemoine, Frederique

    2013-12-01

    In the context of new generation rare isotope beam facilities based on high-power heavy-ion accelerators and in-flight separation of the reaction products, the design of the rare isotope production targets is a major challenge. In order to provide high-purity beams for science, high resolution is required in the rare isotope separation. This demands a small beam spot on the production target which, together with the short range of heavy ions in matter, leads to very high power densities inside the target material. This paper gives an overview of the challenges associated with this high power density, discusses radiation damage issues in targets exposed to heavy ion beams, and presents recent developments to meet some of these challenges through different projects: FAIR, RIBF and FRIB which is the most challenging. Extensive use of Finite Element Analysis (FEA) has been made at all facilities to specify critical target parameters and R&D work at FRIB successfully retired two major risks related to high-power density and heavy-ion induced radiation damage.

  17. Determination of the atomic density of rubidium-87

    NASA Astrophysics Data System (ADS)

    Zhao, Meng; Zhang, Kai; Chen, Li-Qing

    2015-09-01

    Atomic density is a basic and important parameter in quantum optics, nonlinear optics, and precision measurement. In the past few decades, several methods have been used to measure atomic density, such as thermionic effect, optical absorption, and resonance fluorescence. The main error of these experiments stemmed from depopulation of the energy level, self-absorption, and the broad bandwidth of the laser. Here we demonstrate the atomic density of 87Rb vapor in paraffin coated cell between 297 K and 334 K mainly using fluorescence measurement. Optical pumping, anti-relaxation coating, and absorption compensation approaches are used to decrease measurement error. These measurement methods are suitable for vapor temperature at dozens of degrees. The fitting function for the experimental data of 87Rb atomic density is given. Project supported by the Natural Science Foundation of China (Grant Nos. 11274118 and 11474095), the Innovation Program of Shanghai Municipal Education Commission of China (Grant No. 13ZZ036), and the Fundamental Research Funds for the Central Universities of China.

  18. Gedanken densities and exact constraints in density functional theory

    SciTech Connect

    Perdew, John P.; Ruzsinszky, Adrienn; Sun, Jianwei; Burke, Kieron

    2014-05-14

    Approximations to the exact density functional for the exchange-correlation energy of a many-electron ground state can be constructed by satisfying constraints that are universal, i.e., valid for all electron densities. Gedanken densities are designed for the purpose of this construction, but need not be realistic. The uniform electron gas is an old gedanken density. Here, we propose a spherical two-electron gedanken density in which the dimensionless density gradient can be an arbitrary positive constant wherever the density is non-zero. The Lieb-Oxford lower bound on the exchange energy can be satisfied within a generalized gradient approximation (GGA) by bounding its enhancement factor or simplest GGA exchange-energy density. This enhancement-factor bound is well known to be sufficient, but our gedanken density shows that it is also necessary. The conventional exact exchange-energy density satisfies no such local bound, but energy densities are not unique, and the simplest GGA exchange-energy density is not an approximation to it. We further derive a strongly and optimally tightened bound on the exchange enhancement factor of a two-electron density, which is satisfied by the local density approximation but is violated by all published GGA's or meta-GGA’s. Finally, some consequences of the non-uniform density-scaling behavior for the asymptotics of the exchange enhancement factor of a GGA or meta-GGA are given.

  19. Density Gradients in Chemistry Teaching

    ERIC Educational Resources Information Center

    Miller, P. J.

    1972-01-01

    Outlines experiments in which a density gradient might be used to advantage. A density gradient consists of a column of liquid, the composition and density of which varies along its length. The procedure can be used in analysis of solutions and mixtures and in density measures of solids. (Author/TS)

  20. Energy levels and crystal field parameters for Nd3+ ions in BaY2F8, LiKYF5, and K2YF5 single crystals.

    PubMed

    Karbowiak, M; Gnutek, P; Rudowicz, C

    2012-02-15

    The available experimental energy levels of Nd(3+) ions doped into single crystals of BaY(2)F(8), LiKYF(5), and K(2)YF(5), which exhibit low site symmetry, are reanalyzed. A combined approach based on the ascent/descent in symmetry (ADS) method, the superposition model (SPM) analysis, and the pseudosymmetry axes method (PAM) is utilized to extract the crystal field (CF) parameters, B(kq), from experimental spectra. Corresponding sets of the free-ion parameters are also fitted. The crystallographic data are used to establish the axis systems most appropriate for approximation of the actual monoclinic C(2) site symmetry to higher orthorhombic D(2) and tetragonal D(4) symmetry used in CF calculations for BaY(2)F(8). Similarly, for triclinic C(1) site symmetry in LiKYF(5) and K(2)YF(5) approximation to monoclinic C(2) and orthorhombic D(2) symmetry for LiKYF(5), whereas the monoclinic C(s) symmetry for K(2)YF(5), are considered. It is shown that the C(2v) approximation used previously for K(2)YF(5):Nd(3+) is not suitable. SPM enables to calculate for the unapproximated and idealized polyhedrons YF(8) in a given ion-host system of the combined coordination factors Sg(k,q) expressed in the modified crystallographic axis system CAS* and approximated symmetry adapted axis systems, respectively. The quantities Sg(k,q) serve as input for PAM calculations for independent determination of the axis system appropriate for higher symmetry approximations. The pseudosymmetry axes represent the axis system that reflects most closely the approximated higher symmetry of the nearest ligands in a paramagnetic complex embodied in the 4th-rank CF parameters. The combined ADS/SPM/PAM approach provides sets of starting CF parameters (CFPs) in well-defined axis systems. Multiple fittings starting from different points in the CF parameter space yield converging solutions, thus increasing the reliability of the final optimized solutions, which may be then considered as the global minima. The

  1. Crystal-field analysis and Zeeman splittings of energy levels of Nd{sup 3+} (4f{sup 3}) in GaN

    SciTech Connect

    Gruber, John B.; Chandra, Sreerenjini; Sardar, Dhiraj K.; Burdick, Gary W.; Woodward, Nathaniel T.; Dierolf, Volkmar

    2011-08-15

    The crystal-field splitting and Zeeman splitting of energy levels of Nd{sup 3+} (4f{sup 3}) doped into semi-conducting GaN (3.2 eV) grown in the hexagonal (huntite) phase by plasma-assisted molecular beam epitaxy have been modeled using a parameterized Hamiltonian defined to operate within the complete 4f{sup 3} electronic configuration of Nd{sup 3+} substituted for Ga{sup 3+} in the lattice. Zeeman splittings were obtained by applying magnetic fields up to 6.6 T with the fields parallel and perpendicular to the crystallographic c-axis. The experimental energy (Stark) levels were obtained from a recent spectroscopic study on the same samples, where the combined excitation emission spectroscopy (CEES) identified the majority of Nd{sup 3+} ions as replacing Ga{sup 3+} in sites of C{sub 3v} symmetry. The manifolds of Nd{sup 3+} (4f{sup 3}){sup 2S+1}L{sub J} modeled for the crystal-field splitting include the ground state, {sup 4}I{sub 9/2}, and excited states {sup 4}I{sub 11/2}, {sup 4}I{sub 13/2}, {sup 4}F{sub 3/2}, {sup 4}F{sub 5/2}, {sup 2}H{sub 9/2}, {sup 4}F{sub 7/2}, {sup 4}S{sub 3/2}, {sup 4}G{sub 5/2}, and {sup 4}G{sub 7/2}. The energies of 41 experimental Stark levels from these manifolds were modeled through the use of a Monte Carlo method in which independent crystal-field parameters (CFP) were given random starting values and optimized using standard least-squares fitting between calculated and experimental Stark levels. Irreducible representations (irreps) and crystal field quantum numbers ({mu}) were assigned to the energy level states of the {sup 4}I{sub 9/2} and {sup 4}F{sub 3/2} multiplet manifolds based on an analysis of the Zeeman data. This allows determination of which of the competing local minima should be considered to be the physically significant minimum. Using standard least-squares fitting between calculated and experimental Stark levels for Nd{sup 3+} in C{sub 3v} symmetry, we obtain a final standard deviation of 7.01 cm{sup -1} (rms = 5

  2. The Effect of OPC Factor™ on Energy Levels in Healthy Adults Ages 45–65: A Phase IIb Randomized Controlled Trial

    PubMed Central

    Farrar, John T.; Sammel, Mary D.; Gallo, Joseph J.

    2008-01-01

    Abstract Objective To determine the efficacy of the food supplement OPC Factor™ to increase energy levels in healthy adults aged 45 to 65. Design Randomized, placebo-controlled, triple-blind crossover study. Subjects Twenty-five (25) healthy adults recruited from the University of Pennsylvania Health System. Interventions OPC Factor,™ (AlivenLabs, Lebanon, TN) a food supplement that contains oligomeric proanthocyanidins from grape seeds and pine bark along with other nutrient supplements including vitamins and minerals, was in the form of an effervescent powder. The placebo was similar in appearance and taste. Outcome measures Five outcome measurements were performed: (1) Energy subscale scores of the Activation–Deactivation Adjective Check List (AD ACL); (2) One (1) global question of percent energy change (Global Energy Percent Change); (3) One (1) global question of energy change measured on a Likert scale (Global Energy Scale Change); 4. One (1) global question of percent overall status change (Global Overall Status Percent Change); and (5) One (1) global question of overall status change measured on a Likert scale (Global Overall Status Scale Change). Results There were no carryover/period effects in the groups randomized to Placebo/Active Product sequence versus Active Product/Placebo sequence. Examination of the AD ACL Energy subscale scores for the Active Product versus Placebo comparison revealed no significant difference in the intention-to-treat (IT) analysis and the treatment received (TR) analysis. However, Global Energy Percent Change (p = 0.06) and Global Energy Scale Change (p = 0.09) both closely approached conventional levels of statistical significance for the active product in the IT analysis. Global Energy Percent Change (p = 0.05) and Global Energy Scale Change (p = 0.04) reached statistical significance in the TR analysis. A cumulative percent responders analysis graph indicated greater response rates for the active

  3. High Energy Density Capacitors

    SciTech Connect

    2010-07-01

    BEEST Project: Recapping is developing a capacitor that could rival the energy storage potential and price of today’s best EV batteries. When power is needed, the capacitor rapidly releases its stored energy, similar to lightning being discharged from a cloud. Capacitors are an ideal substitute for batteries if their energy storage capacity can be improved. Recapping is addressing storage capacity by experimenting with the material that separates the positive and negative electrodes of its capacitors. These separators could significantly improve the energy density of electrochemical devices.

  4. Highly accurate potential energy surface, dipole moment surface, rovibrational energy levels, and infrared line list for ³²S¹⁶O₂ up to 8000 cm⁻¹.

    PubMed

    Huang, Xinchuan; Schwenke, David W; Lee, Timothy J

    2014-03-21

    A purely ab initio potential energy surface (PES) was refined with selected (32)S(16)O2 HITRAN data. Compared to HITRAN, the root-mean-squares error (σ(RMS)) for all J = 0-80 rovibrational energy levels computed on the refined PES (denoted Ames-1) is 0.013 cm(-1). Combined with a CCSD(T)/aug-cc-pV(Q+d)Z dipole moment surface (DMS), an infrared (IR) line list (denoted Ames-296K) has been computed at 296 K and covers up to 8000 cm(-1). Compared to the HITRAN and CDMS databases, the intensity agreement for most vibrational bands is better than 85%-90%. Our predictions for (34)S(16)O2 band origins, higher energy (32)S(16)O2 band origins and missing (32)S(16)O2 IR bands have been verified by most recent experiments and available HITRAN data. We conclude that the Ames-1 PES is able to predict (32/34)S(16)O2 band origins below 5500 cm(-1) with 0.01-0.03 cm(-1) uncertainties, and the Ames-296K line list provides continuous, reliable and accurate IR simulations. The K(a)-dependence of both line position and line intensity errors is discussed. The line list will greatly facilitate SO2 IR spectral experimental analysis, as well as elimination of SO2 lines in high-resolution astronomical observations. PMID:24655184

  5. Assisted extraction of the energy level spacings and lever arms in direct current bias measurements of one-dimensional quantum wires, using an image recognition routine

    SciTech Connect

    Lesage, A. A. J. Smith, L. W. Griffiths, J. P.; Farrer, I.; Jones, G. A. C.; Ritchie, D. A.; Smith, C. G.; Al-Taie, H.; Kelly, M. J.; See, P.

    2015-01-07

    A multiplexer technique is used to individually measure an array of 256 split gates on a single GaAs/AlGaAs heterostructure. This results in the generation of large volumes of data, which requires the development of automated data analysis routines. An algorithm is developed to find the spacing between discrete energy levels, which form due to transverse confinement from the split gate. The lever arm, which relates split gate voltage to energy, is also found from the measured data. This reduces the time spent on the analysis. Comparison with estimates obtained visually shows that the algorithm returns reliable results for subband spacing of split gates measured at 1.4 K. The routine is also used to assess direct current bias spectroscopy measurements at lower temperatures (50 mK). This technique is versatile and can be extended to other types of measurements. For example, it is used to extract the magnetic field at which Zeeman-split 1D subbands cross one another.

  6. Energy level analysis of Np/sup 3 +/:LaCl/sub 3/ and Np/sup 3 +/:LaBr/sub 3/

    SciTech Connect

    Carnall, W.T.; Crosswhite, H.; Crosswhite, H.M.; Hessler, J.P.; Edelstein, N.; Conway, J.G.; Shalimoff, G.V.; Sarup, R.

    1980-05-01

    The polarized absorption and fluorescence spectra of 0.01--5% Np/sup 3 +/ doped into single-crystal LaCl/sub 3/ were measured at moderate and high resolution in the range to 50 000 cm/sup -1/ at 298, 77, and 4 K. The 150 crystal field components identified were fit by a parametrized model which has previously been shown to provide an excellent account of the energy level structures observed for lanthanides doped into LaCl/sub 3/. This constitutes the first successful evaluation of the crystal field interaction for an actinide ion in LaCl/sub 3/ in which J mixing effects were explicitly included. The crystal field parameters for Np/sup 3 +/:LaCl/sub 3/, B/sup 2//sub 0/=163, B/sup 4//sub 0/=-632, B/sup 6//sub 0/=-1625, and B/sup 6//sub 6/=1028, all in cm/sup -1/, were determined to be approximately twice as large as those for the analogous lanthanide, Pm/sup 3 +/:LaCl/sub 3/. From analysis of Zeeman patterns in the fluorescence spectra, the ground state was found to be doubly degenerate, having crystal quantum numbers +- 2 and a parallel splitting factor 0.17 LU (Lorentz unit).

  7. Dual-Energy Computed Tomography Arthrography of the Shoulder Joint Using Virtual Monochromatic Spectral Imaging: Optimal Dose of Contrast Agent and Monochromatic Energy Level

    PubMed Central

    An, Chansik; Chun, Yong-Min; Kim, Sungjun; Lee, Young Han; Yun, Min Jeong; Suh, Jin-Suck

    2014-01-01

    Objective To optimize the dose of contrast agent and the level of energy for dual-energy computed tomography (DECT) arthrography of the shoulder joint and to evaluate the benefits of the optimized imaging protocol. Materials and Methods Dual-energy scans with monochromatic spectral imaging mode and conventional single energy scans were performed on a shoulder phantom with 10 concentrations from 0 to 210 mg/mL of iodinated contrast medium at intervals of 15 or 30 mg/mL. Image noise, tissue contrast, and beam hardening artifacts were assessed to determine the optimum dose of contrast agent and the level of monochromatic energy for DECT shoulder arthrography in terms of the lowest image noise and the least beam hardening artifacts while good tissue contrast was maintained. Material decomposition (MD) imaging for bone-iodine differentiation was qualitatively assessed. The optimized protocol was applied and evaluated in 23 patients. Results The optimal contrast dose and energy level were determined by the phantom study at 60 mg/mL and 72 keV, respectively. This optimized protocol for human study reduced the image noise and the beam-hardening artifacts by 35.9% and 44.5%, respectively. Bone-iodine differentiation by MD imaging was not affected by the iodine concentration or level of energy. Conclusion Dual-energy scan with monochromatic spectral imaging mode results in reduced image noise and beam hardening artifacts. PMID:25469086

  8. Location of trivalent lanthanide dopant energy levels in (Lu{sub 0.5}Gd{sub 0.5}){sub 2}O{sub 3}

    SciTech Connect

    Retot, H.; Viana, B.; Bessiere, A.; Galtayries, A.

    2011-06-15

    The location of Ln{sup 3+} dopant energy levels relative to bands in (Lu{sub 0.5}Gd{sub 0.5}){sub 2}O{sub 3} was studied. A several-steps analysis of XPS measurements on heavy lanthanides sesquioxides Ln{sub 2}O{sub 3} (Ln = Gd, Tb, Dy, Er, Tm, Yb, Lu) and on Sc{sub 2}O{sub 3} and Y{sub 2}O{sub 3} reference materials were used to locate Ln{sup 3+} dopant ground state relative to the top of the valence band in (Lu{sub 0.5}Gd{sub 0.5}){sub 2}O{sub 3} within an error bar of {+-}0.4 eV. The agreement between XPS data and model was found improved relative to previous studies. When compared to XPS analysis, prediction based on optical absorption shows a slight underestimation attributed to the lack of precision in Ce{sup 4+} charge transfer band measurement.

  9. Energy levels of terbium(III) in the elpasolite Cs2NaTbBr6. II. A correlation crystal field analysis

    NASA Astrophysics Data System (ADS)

    McCaw, C. S.; Denning, R. G.

    A set of more than 100 electronic energy levels in Cs2NaTbBr6, extending from the ground state to 5H4, is used to test different models of the correlation crystal field (CCF). These are based on Judd's orthogonal g(k)iQ two-electron operators, and more specifically on contributions due to spin-correlation, or ligand polarization. Similar data from Cs2NaTbCl6 and Cs2NaTbF6 has also been analysed. Only fourth-rank operators make clear improvements to the quality of the fit in deviant multiplets. Empirically the g7(4) and g9(4) operators are found to be the most effective. Although fourth-rank operators achieve modest success in correcting the calculated spread of the multiplets, no single operator has a significant impact on the shortcomings of the one-body crystal field. This result is discussed in terms of the limitations of an effective-operator Hamiltonian.

  10. Correlation of open-circuit voltage and energy levels in zinc-phthalocyanine: C60 bulk heterojunction solar cells with varied mixing ratio

    NASA Astrophysics Data System (ADS)

    Tietze, Max L.; Tress, Wolfgang; Pfützner, Steffen; Schünemann, Christoph; Burtone, Lorenzo; Riede, Moritz; Leo, Karl; Vandewal, Koen; Olthof, Selina; Schulz, Philip; Kahn, Antoine

    2013-08-01

    The maximum open-circuit voltage VOC of bulk-heterojunction solar cells is limited by the effective HOMO(donor)-LUMO(acceptor) gap of the photoactive absorber blend. We investigate blend layers comprising zinc-phthalocyanine (ZnPc) and the buckminster fullerene C60 with ultraviolet, x-ray, and inverse photoelectron spectroscopy. By varying the volume mixing ratio ZnPc:C60 from 6:1 to 1:6, we observe a linear increase of the HOMO(ZnPc)-LUMO(C60) gap by 0.25 eV. The trend in this gap correlates with the change in the charge transfer energy measured by Fourier-transform photocurrent spectroscopy as well as with the observed open-circuit voltage of solar cells containing ZnPc:C60 as the photoactive absorber layer. Furthermore, the morphology of different ZnPc:C60 blend layers is investigated by grazing-incidence x-ray diffraction. As physical origins for the changed energy levels, a suppressed crystallization of the C60 phase in the presence of donor molecules as well as concentration-dependent growth modes of the ZnPc phase are suggested.

  11. Tuning of the stability and energy levels of singlet exciton fission relevant excited states of pentacenes by site-specific substitution.

    PubMed

    Shen, Li; Chen, Yuhan; Li, Xiyou; Li, Chungang

    2016-05-01

    Pentacene crystals or oligomers undergo efficient singlet exciton fission (SF) after photo-excitation, which is expected to be useful in overcoming the Shockley-Queisser theoretical limit of solar cells. However, pentacenes are extremely unstable in air due to oxidation by oxygen. In this work, we designed a group of pentacene compounds with different substituents at different positions. The energy levels of HOMO and LUMO, which are believed to be closely related to the stability of pentacene, were calculated. The relationship between the molecular structure and the stability was discussed. The driving force for SF was estimated from the difference between the energy of first singlet excited state (E(S1)) and the energy of two triplet excited state (2×E(T1)) following equation E(S1)-2E(T1). Strong electron-withdrawing groups can stabilize pentacene compounds significantly, but induce a decrease on the driving force of SF slightly. Electron-donating groups destabilize the pentacene compounds dramatically and hence the introduction of electron donating groups to pentacene is not recommended. TIPS is an ideal group to improve the stability of pentacene compounds. TIPS does not change the driving force of SF significantly. Sulfur containing groups are also efficient on stabilizing pentacene compounds. These groups increase the driving force of SF at ɑ position, and recued the driving force of SF at other positions. The results of this work provide a theoretical ground for rational design of new SF molecules based on pentacenes. PMID:27131283

  12. Rotational energy surface and quasiclassical analysis of the rotational energy level cluster formation in the ground vibrational state of PH 3

    NASA Astrophysics Data System (ADS)

    Petrov, Sergey V.; Kozlovskii, Borislav M.

    2007-06-01

    We report and substantiate a method for constructing the rotational energy surface (RES) of a molecule as a pure classical object. For an arbitrary molecule we start from the potential energy surface rather than from a conventional "effective Hamiltonian". The method is used for constructing the RES of the PH 3 molecule in its ground vibrational state. We have used an ab initio potential energy surface [D. Wang, Q. Shi, Q.-S. Zhu, J. Chem. Phys. 112 (2000) 9624-9631; S.N. Yurchenko, M. Carvajal, P. Jensen, F. Herregodts, T.R. Huet, Chem. Phys. 290 (2003) 59-67.]. The shape of the RES is shown not to change for J from 0 to 120. The procedure of quasiclassical quantization of the RES was also undertaken, yielding a set of quasiclassical critical values of the angular momentum. The results explain the structure of quantum rotational energy levels obtained by variational calculations [S.N. Yurchenko, W. Thiel, S. Patchkovskii, P. Jensen, Phys. Chem. Chem. Phys. 7 (2005) 573-582].

  13. Alignment of energy levels at the Alq3/La0.7Sr0.3MnO3 interface for organic spintronic devices

    NASA Astrophysics Data System (ADS)

    Zhan, Y. Q.; Bergenti, I.; Hueso, L. E.; Dediu, V.; de Jong, M. P.; Li, Z. S.

    2007-07-01

    The electronic structure of the interface between tris(8-hydroxyquinolino)-aluminum (Alq3) and La0.7Sr0.3MnO3 (LSMO) manganite was investigated by means of photoelectron spectroscopy. As demonstrated recently, this interface is characterized by efficient spin injection in organic spintronic devices. We detected a strong interface dipole of about 0.9eV that shifts down the whole energy diagram of the Alq3 with respect to the vacuum level. This modifies the height of the barrier for the injection into highest occupied molecular orbital level to 1.7eV , indicating more difficult hole injection at this interface than expected for the undistorted energy level diagram. We believe that the interface dipole is due to the intrinsic dipole moment of the Alq3 layer. The presented data lead to significant progress in understanding the electronic structure of LSMO/Alq3 interface and represent a step toward the description of spin transport in organic spin valves.

  14. Highly Accurate Potential Energy Surface, Dipole Moment Surface, Rovibrational Energy Levels, and Infrared Line List for (32)S(16)O2 up to 8000 cm(exp -1)

    NASA Technical Reports Server (NTRS)

    Huang, Xinchuan; Schwenke, David W.; Lee, Timothy J.

    2014-01-01

    A purely ab initio potential energy surface (PES) was refined with selected (32)S(16)O2 HITRAN data. Compared to HITRAN, the root-mean-squares error (RMS) error for all J=0-80 rovibrational energy levels computed on the refined PES (denoted Ames-1) is 0.013 cm(exp -1). Combined with a CCSD(T)/aug-cc-pV(Q+d)Z dipole moment surface (DMS), an infrared (IR) line list (denoted Ames-296K) has been computed at 296K and covers up to 8,000 cm(exp -1). Compared to the HITRAN and CDMS databases, the intensity agreement for most vibrational bands is better than 85-90%. Our predictions for (34)S(16)O2 band origins, higher energy (32)S(16)O2 band origins and missing (32)S(16)O2 IR bands have been verified by most recent experiments and available HITRAN data. We conclude that the Ames-1 PES is able to predict (32/34)S(16)O2 band origins below 5500 cm(exp -1) with 0.01-0.03 cm(exp -1) uncertainties, and the Ames-296K line list provides continuous, reliable and accurate IR simulations. The Ka-dependence of both line position and line intensity errors is discussed. The line list will greatly facilitate SO2 IR spectral experimental analysis, as well as elimination of SO2 lines in high-resolution astronomical observations.

  15. SIMPRE: a software package to calculate crystal field parameters, energy levels, and magnetic properties on mononuclear lanthanoid complexes based on charge distributions.

    PubMed

    Baldoví, José J; Cardona-Serra, Salvador; Clemente-Juan, Juan M; Coronado, Eugenio; Gaita-Ariño, Alejandro; Palii, Andrew

    2013-08-15

    This work presents a fortran77 code based on an effective electrostatic model of point charges around a rare earth ion. The program calculates the full set of crystal field parameters, energy levels spectrum, and wave functions, as well as the magnetic properties such as the magnetization, the temperature dependence of the magnetic susceptibility, and the Schottky contribution to the specific heat. It is designed for real systems that need not bear ideal symmetry and it is able to determine the easy axis of magnetization. Its systematic application to different coordination environments allows magneto-structural studies. The package has already been successfully applied to several mononuclear systems with single-molecule magnetic behavior. The determination of effective point charge parameters in these studies facilitates its application to new systems. In this article, we illustrate its usage with two example studies: (a) an ideal cubic structure coordinating a lanthanoid ion and (b) a system with slow relaxation of the magnetization, LiHo(x)Y((1-x))F(4). PMID:24000391

  16. Accurate multiconfiguration calculations of energy levels, lifetimes, and transition rates for the silicon isoelectronic sequence. Ti IX - Ge XIX, Sr XXV, Zr XXVII, Mo XXIX

    NASA Astrophysics Data System (ADS)

    Jönsson, P.; Radžiūtė, L.; Gaigalas, G.; Godefroid, M. R.; Marques, J. P.; Brage, T.; Froese Fischer, C.; Grant, I. P.

    2016-01-01

    Multiconfiguration Dirac-Hartree-Fock (MCDHF) calculations and relativistic configuration interaction (RCI) calculations are performed for states of the 3s23p2, 3s3p3 and 3s23p3d configurations in the Si-like ions Ti IX - Ge XIX, Sr XXV, Zr XXVII and Mo XXIX. Valence and core-valence electron correlation effects are accounted for through large configuration state function expansions. Calculated energy levels are compared with data from other calculations and with experimental data from the reference databases. Lifetime and transition rates along with uncertainty estimations are given for all ions. Energies from the calculations are in excellent agreement with observations and computed wavelength are almost of spectroscopic accuracy, aiding line identification in spectra. Full Tables 2, 3, and 5 are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/585/A26

  17. Defect energy levels in p-type GaAsBi and GaAs grown by MBE at low temperatures

    NASA Astrophysics Data System (ADS)

    Mooney, P. M.; Tarun, M. C.; Bahrami-Yekta, V.; Tiedje, T.; Lewis, R. B.; Masnadi-Shirazi, M.

    2016-06-01

    Deep level defects in p-type GaAs1‑x Bi x (x < 1%) and GaAs grown by molecular beam epitaxy at substrate temperatures of 330 °C and 370 °C have been characterized by deep level transient spectroscopy. We find that incorporating Bi into GaAs at 330 °C does not affect the total concentration of hole traps, which is ∼4 × 1016 cm‑3, comparable to the concentration of electron traps observed in Si-doped GaAsBi having a similar alloy composition. Increasing the growth temperature of the p-type GaAsBi (x = 0.8%) layer from 330 °C to 370 °C reduces the hole trap concentration by an order of magnitude. Moreover, the defects having near mid-gap energy levels that are the most efficient non-radiative recombination centers are present only in GaAsBi layers grown at the lower temperature. These new results are discussed in the context of previous measurements of n-type GaAs and GaAsBi layers grown under similar conditions.

  18. Gluon density in nuclei

    SciTech Connect

    Ayala, A.L.; Ducati, M.B.G.; Levin, E.M.

    1996-10-01

    In this talk we present our detailed study (theory and numbers) on the shadowing corrections to the gluon structure functions for nuclei. Starting from rather controversial information on the nucleon structure function which is originated by the recent HERA data, we develop the Glauber approach for the gluon density in a nucleus based on Mueller formula and estimate the value of the shadowing corrections in this case. Then we calculate the first corrections to the Glauber approach and show that these corrections are big. Based on this practical observation we suggest the new evolution equation which takes into account the shadowing corrections and solve it. We hope to convince you that the new evolution equation gives a good theoretical tool to treat the shadowing corrections for the gluons density in a nucleus and, therefore, it is able to provide the theoretically reliable initial conditions for the time evolution of the nucleus-nucleus cascade. The initial conditions should be fixed both theoretically and phenomenologically before to attack such complicated problems as the mixture of hard and soft processes in nucleus-nucleus interactions at high energy or the theoretically reliable approach to hadron or/and parton cascades for high energy nucleus-nucleus interaction. 35 refs., 24 figs., 1 tab.

  19. Oblique dust density waves

    NASA Astrophysics Data System (ADS)

    Piel, Alexander; Arp, Oliver; Menzel, Kristoffer; Klindworth, Markus

    2007-11-01

    We report on experimental observations of dust density waves in a complex (dusty) plasma under microgravity. The plasma is produced in a radio-frequency parallel-plate discharge (argon, p=15Pa, U=65Vpp). Different sizes of dust particles were used (3.4 μm and 6.4μm diameter). The low-frequency (f 11Hz) dust density waves are naturally unstable modes, which are driven by the ion flow in the plasma. Surprisingly, the wave propagation direction is aligned with the ion flow direction in the bulk plasma but becomes oblique at the boundary of the dust cloud with an inclination of 60^o with respect to the plasma boundary. The experimental results are compared with a kinetic model in the electrostatic approximation [1] and a fluid model [2]. Moreover, the role of dust surface waves is discussed. [1] M. Rosenberg, J. Vac. Sci. Technol. A 14, 631 (1996) [2] A. Piel et al, Phys. Rev. Lett. 97, 205009 (2006)

  20. Density functional theory an effective method to model polythiophenes

    NASA Astrophysics Data System (ADS)

    Venkateswaran, S.

    The luminescent polymer, poly[2-(3-thienyl)ethanol butoxycarbonyl-methyl urethane, called popularly as PURET, has rekindled research interests due to the recent discovery of its ability for detection of explosives at trace levels of molecules in their vapor phase. In this computational study, Hartree-Fock and/or Density Functional Theory (DFT) methods are applied, using Gaussian09 W software, for calculating the HOMO-LUMO energy levels, the Dipole Moment, and the UV-Vis and IR spectra for the Oligomers of PURET monomer, dimer, and trimer. Similar calculations for a few other Thiophene derivatives, such as TAA. TMA, 3HT, and TTZ, are also shown. DFT-based calculations, employing especially the B3LYP functional, are shown to systematically converge to experimental levels of accuracy for PURET Oligomers.

  1. Correlation of materials properties with the atomic density concept

    NASA Technical Reports Server (NTRS)

    1975-01-01

    Based on the hypothesis that the number of atoms per unit volume, accurately calculable for any substance of known real density and chemical composition, various characterizing parameters (energy levels of electrons interacting among atoms of the same or different kinds, atomic mass, bond intensity) were chosen for study. A multiple exponential equation was derived to express the relationship. Various properties were examined, and correlated with the various parameters. Some of the properties considered were: (1) heat of atomization, (2) boiling point, (3) melting point, (4) shear elastic modulus of cubic crystals, (5) thermal conductivity, and (6) refractive index for transparent substances. The solid elements and alkali halides were the materials studied. It is concluded that the number of different properties can quantitively be described by a common group of parameters for the solid elements, and a wide variety of compounds.

  2. Fundamental gap of molecular crystals via constrained density functional theory

    NASA Astrophysics Data System (ADS)

    Droghetti, Andrea; Rungger, Ivan; Das Pemmaraju, Chaitanya; Sanvito, Stefano

    2016-05-01

    The energy gap of a molecular crystal is one of the most important properties since it determines the crystal charge transport when the material is utilized in electronic devices. This is, however, a quantity difficult to calculate and standard theoretical approaches based on density functional theory (DFT) have proven unable to provide accurate estimates. In fact, besides the well-known band-gap problem, DFT completely fails in capturing the fundamental gap reduction occurring when molecules are packed in a crystal structures. The failure has to be associated with the inability of describing the electronic polarization and the real space localization of the charged states. Here we describe a scheme based on constrained DFT, which can improve upon the shortcomings of standard DFT. The method is applied to the benzene crystal, where we show that accurate results can be achieved for both the band gap and also the energy level alignment.

  3. Low density microcellular foams

    DOEpatents

    LeMay, J.D.

    1991-11-19

    Disclosed is a process of producing microcellular foam which comprises the steps of: (a) selecting a multifunctional epoxy oligomer resin; (b) mixing said epoxy resin with a non-reactive diluent to form a resin-diluent mixture; (c) forming a diluent containing cross-linked epoxy gel from said resin-diluent mixture; (d) replacing said diluent with a solvent therefore; (e) replacing said solvent with liquid carbon dioxide; and (f) vaporizing off said liquid carbon dioxide under supercritical conditions, whereby a foam having a density in the range of 35-150 mg/cc and cell diameters less than about 1 [mu]m is produced. Also disclosed are the foams produced by the process. 8 figures.

  4. Low density microcellular foams

    DOEpatents

    LeMay, James D.

    1992-01-01

    Disclosed is a process of producing microcellular from which comprises the steps of: (a) selecting a multifunctional epoxy oligomer resin; (b) mixing said epoxy resin with a non-reactive diluent to form a resin-diluent mixture; (c) forming a diluent containing cross-linked epoxy gel from said resin-diluent mixture; (d) replacing said diluent with a solvent therefore; (e) replacing said solvent with liquid carbon dioxide; and (f) vaporizing off said liquid carbon dioxide under supercritical conditions, whereby a foam having a density in the range of 35-150 mg/cc and cell diameters less than about 1 .mu.m is produced. Also disclosed are the foams produced by the process.

  5. Low density microcellular foams

    DOEpatents

    LeMay, James D.

    1991-01-01

    Disclosed is a process of producing microcellular foam which comprises the steps of: (a) selecting a multifunctional epoxy oligomer resin; (b) mixing said epoxy resin with a non-reactive diluent to form a resin-diluent mixture; (c) forming a diluent containing cross-linked epoxy gel from said resin-diluent mixture; (d) replacing said diluent with a solvent therefore; (e) replacing said solvent with liquid carbon dioxide; and (f) vaporizing off said liquid carbon dioxide under supercritical conditions, whereby a foam having a density in the range of 35-150 mg/cc and cell diameters less than about 1 .mu.m is produced. Also disclosed are the foams produced by the process.

  6. Density distribution in Earth.

    PubMed

    Press, F

    1968-06-14

    Earth models selected by a Monte Carlo procedure were tested against geophysical data; 5 million models were examined and six have passed all tests. Common features of successful models are an increased core radius and a chemically inhomogeneous core consistent with Fe-Ni alloy (20 to 50 percent Fe) for the solid portion and Fe-Si alloy (15 to 25 percent Fe) for the fluid core. The inhomogeneous mantle is consistent with an increase in the FeO:FeO + MgO ratio by a factor of 2 in the deep mantle. The transition zone is a region of not only phase change but also composition change; this condition would inhibit mantlewide convection. The upper-mantle solutions show large fluctuations in density; this state implies insufficient constraint on solutions for this region, or lateral variations in mantle composition ranging from pyrolite to eclogite. PMID:17818740

  7. Nuclear Energy Density Optimization

    SciTech Connect

    Kortelainen, Erno M; Lesinski, Thomas; More, J.; Nazarewicz, W.; Sarich, J.; Schunck, N.; Stoitsov, M. V.; Wild, S.

    2010-01-01

    We carry out state-of-the-art optimization of a nuclear energy density of Skyrme type in the framework of the Hartree-Fock-Bogoliubov (HFB) theory. The particle-hole and particle-particle channels are optimized simultaneously, and the experimental data set includes both spherical and deformed nuclei. The new model-based, derivative-free optimization algorithm used in this work has been found to be significantly better than standard optimization methods in terms of reliability, speed, accuracy, and precision. The resulting parameter set UNEDFpre results in good agreement with experimental masses, radii, and deformations and seems to be free of finite-size instabilities. An estimate of the reliability of the obtained parameterization is given, based on standard statistical methods. We discuss new physics insights offered by the advanced covariance analysis.

  8. Interstellar Electron Density Spectra

    NASA Astrophysics Data System (ADS)

    Lambert, Hendrick Clark

    This study concerns the investigation of the form of the wavenumber spectrum of the Galactic electron density fluctuations through an examination of the scattering of the radio pulses emitted by pulsars as they propagate through the diffuse ionized interstellar gas. A widely used model for the electron density spectrum is based on the simple power-law: Pne(q)∝ q-β, where β = 11/3 is usually assumed, corresponding to Kolmogorov's turbulence spectrum. The simple Kolmogorov model provides satisfactory agreement for observations along many lines of sight; however, major inconsistencies remain. The inconsistencies suggest that an increase in the ratio of the power between the high (10-8[ m]-1≤ q<=10-7[ m]-1) and low (10-13[ m]-1≤ q<=10-12[ m]-1) wavenumbers is needed. This enhancement in the ratio can in turn be achieved by either including an inner scale, corresponding to a dissipation scale for the turbulent cascade, in the Kolmogorov spectrum or by considering steeper spectra. Spectra with spectral exponents β > 4 have been in general rejected based on observations of pulsar refractive scintillations. The special case of β = 4 has been given little attention and is analyzed in detail. Physically, this 'β = 4' model corresponds to the random distribution, both in location and orientation, of discrete objects with relatively sharp boundaries across the line of sight. An outer scale is included in the model to account for the average size of such objects. We compare the predictions of the inner-scale and β = 4 models both with published observations and observations we made as part of this investigation. We conclude that the form of the wavenumber spectrum is dependent on the line of sight. We propose a composite spectrum featuring a uniform background turbulence in presence of randomly distributed discrete objects, as modeled by the β = model.

  9. Low density microcellular foams

    DOEpatents

    Aubert, James H.; Clough, Roger L.; Curro, John G.; Quintana, Carlos A.; Russick, Edward M.; Shaw, Montgomery T.

    1987-01-01

    Low density, microporous polymer foams are provided by a process which comprises forming a solution of polymer and a suitable solvent followed by rapid cooling of the solution to form a phase-separated system and freeze the phase-separated system. The phase-separated system comprises a polymer phase and a solvent phase, each of which is substantially continuous within the other. The morphology of the polymer phase prior to and subsequent to freezing determine the morphology of the resultant foam. Both isotropic and anisotropic foams can be produced. If isotropic foams are produced, the polymer and solvent are tailored such that the solution spontaneously phase-separates prior to the point at which any component freezes. The morphology of the resultant polymer phase determines the morphology of the resultant foam and the morphology of the polymer phase is retained by cooling the system at a rate sufficient to freeze one or both components of the system before a change in morphology can occur. Anisotropic foams are produced by forming a solution of polymer and solvent that will not phase separate prior to freezing of one or both components of the solution. In such a process, the solvent typically freezes before phase separation occurs. The morphology of the resultant frozen two-phase system determines the morphology of the resultant foam. The process involves subjecting the solution to essentially one-dimensional cooling. Means for subjecting such a solvent to one-dimensional cooling are also provided. Foams having a density of less than 0.1 g/cc and a uniform cell size of less than 10 .mu.m and a volume such that the foams have a length greater than 1 cm are provided.

  10. Low density microcellular foams

    DOEpatents

    Aubert, J.H.; Clough, R.L.; Curro, J.G.; Quintana, C.A.; Russick, E.M.; Shaw, M.T.

    1985-10-02

    Low density, microporous polymer foams are provided by a process which comprises forming a solution of polymer and a suitable solvent followed by rapid cooling of the solution to form a phase-separated system and freeze the phase-separated system. The phase-separated system comprises a polymer phase and a solvent phase, each of which is substantially continuous within the other. The morphology of the polymer phase prior to and subsequent to freezing determine the morphology of the resultant foam. Both isotropic and anisotropic foams can be produced. If isotropic foams are produced, the polymer and solvent are tailored such that the solution spontaneously phase-separates prior to the point at which any component freezes. The morphology of the resultant polymer phase determines the morphology of the reusltant foam and the morphology of the polymer phase is retained by cooling the system at a rate sufficient to freeze one or both components of the system before a change in morphology can occur. Anisotropic foams are produced by forming a solution of polymer and solvent that will not phase separate prior to freezing of one or both components of the solution. In such a process, the solvent typically freezes before phase separation occurs. The morphology of the resultant frozen two-phase system determines the morphology of the resultant foam. The process involves subjecting the solution to essentially one-dimensional cooling. Foams having a density of less than 0.1 g/cc and a uniform cell size of less than 10 ..mu..m and a volume such that the foams have a length greater than 1 cm are provided.

  11. Comment on ``Multiconfiguration Dirac-Fock energy levels and radiative rates for Br-like tungsten'' by S. Aggarwal, A.K.S. Jha, and M. Mohan [Can. J. Phys. 91, 394 (2013)

    NASA Astrophysics Data System (ADS)

    Aggarwal, Kanti M.; Keenan, Francis P.

    2014-06-01

    We report calculations of energy levels and oscillator strengths for transitions in W XL, undertaken with the general-purpose relativistic atomic structure package ({\\sc grasp}) and flexible atomic code ({\\sc fac}). Comparisons are made with existing results and the accuracy of the data is assessed. Discrepancies with the most recent results of S. Aggarwal et al. [Can. J. Phys. {\\bf 91} (2013) 394] are up to 0.4 Ryd and up to two orders of magnitude for energy levels and oscillator strengths, respectively. Discrepancies for lifetimes are even larger, up to four orders of magnitude for some levels. Our energy levels are estimated to be accurate to better than 0.5% (i.e. 0.2 Ryd), whereas results for oscillator strengths and lifetimes should be accurate to better than 20%.

  12. Density-functional-theory results for Ga and As vacancies in GaAs obtained using the Socorro code.

    SciTech Connect

    Wright, Alan Francis

    2009-09-01

    The Socorro code has been used to obtain density-functional theory results for the Ga vacancy (V{sub Ga}) and the As vacancy (V{sub As}) in GaAs. Calculations were performed in a nominal 216-atom simulation cell using the local-density approximation for exchange and correlation. The results from these calculations include: (1) the charge states, the atomic configurations of stable and metastable states, (2) energy levels in the gap, and (3) activation energies for migration. Seven charge states were found for the Ga vacancy (-3, -2, -1, 0, +1, +2, +3). The stable structures of the -3, -2, -1, and 0 charge states consist of an empty Ga site with four As neighbors displaying T{sub d} symmetry. The stable structures of the +1, +2, and +3 charge states consist of an As antisite next to an As vacancy; AsGa-V{sub As}. Five charge states were found for the As vacancy (-3, -2, -1, 0, +1). The stable structures of the -1, 0, and +1 charge states consist of an empty As site with four Ga neighbors displaying C{sub 2v} symmetry. The stable structures of the -3 and -2 charge states consist of a Ga antisite next to a Ga vacancy; Ga{sub As}-V{sub Ga}. The energy levels of V{sub Ga} lie below mid-gap while the energy levels of As{sub Ga}-V{sub As} lie above and below mid-gap. All but one of the V{sub As} energy levels lie above mid-gap while the As{sub Ga}-V{sub As} energy level lies below mid-gap. The migration activation energies of the defect states were all found to be larger than 1.35 eV.

  13. IUPAC critical evaluation of the rotational-vibrational spectra of water vapor. Part IV. Energy levels and transition wavenumbers for D216O, D217O, and D218O

    NASA Astrophysics Data System (ADS)

    Tennyson, Jonathan; Bernath, Peter F.; Brown, Linda R.; Campargue, Alain; Császár, Attila G.; Daumont, Ludovic; Gamache, Robert R.; Hodges, Joseph T.; Naumenko, Olga V.; Polyansky, Oleg L.; Rothman, Laurence S.; Vandaele, Ann Carine; Zobov, Nikolai F.; Dénes, Nóra; Fazliev, Alexander Z.; Furtenbacher, Tibor; Gordon, Iouli E.; Hu, Shui-Ming; Szidarovszky, Tamás; Vasilenko, Irina A.

    2014-07-01

    This paper is the fourth of a series of papers reporting critically evaluated rotational-vibrational line positions, transition intensities, pressure dependences, and energy levels, with associated critically reviewed assignments and uncertainties, for all the main isotopologues of water. This paper presents energy level and transition data for the following doubly and triply substituted isotopologues of water: D216O, D217O, and D218O. The MARVEL (Measured Active Rotational-Vibrational Energy Levels) procedure is used to determine the levels, the lines, and their self-consistent uncertainties for the spectral regions 0-14 016, 0-7969, and 0-9108 cm-1 for D216O, D217O, and D218O, respectively. For D216O, D217O, and D218O, 53 534, 600, and 12 167 lines are considered, respectively, from spectra recorded in absorption at room temperature and in emission at elevated temperatures. The number of validated energy levels is 12 269, 338, and 3351 for D216O, D217O, and D218O, respectively. The energy levels have been checked against the ones determined, with an average accuracy of about 0.03 cm-1, from variational rovibrational computations employing exact kinetic energy operators and an accurate potential energy surface. Furthermore, the rovibrational labels of the energy levels have been validated by an analysis of the computed wavefunctions using the rigid-rotor decomposition (RRD) scheme. The extensive list of MARVEL lines and levels obtained is deposited in the Supplementary Material of this paper, in a distributed information system applied to water, W@DIS, and on the official MARVEL website, where they can easily be retrieved.

  14. The variable density aircraft concept

    NASA Technical Reports Server (NTRS)

    Davenport, A. C.

    1975-01-01

    In the variable density aircraft concept the aircraft's density is varied by varying its volume. This is accomplished by combining a variable volume hull, which is called the dynapod, with intrinsic means for the controlled variation of a mass of working fluid or substance within the aircraft. The dynapod is a hinged structure and follows the volumetric variations of the working fluid. The result is a variable density hull, which with the attachment of power plants, etc., becomes a variable density aircraft.

  15. Crystal free-ion energy level analysis of Er 3+ (4f 11) in various crystal hosts-oxygen coordinated systems

    NASA Astrophysics Data System (ADS)

    Rukmini, E.; Renuka Devi, A.; Jayasankar, C. K.

    1994-02-01

    Comparative analyses of the Er 3+ (4f 11) crystal free-ion energy level structures in the Er 2O 3, Sc 2O 3, Y 2O 3, YAlO 3, GdAlO 3, SrMoO 4, ThGeO 4, CaWO 4, YVO 4, LuPO 4, Er(OH) 3, ErCl 3·6H 2O, Er(C 2H 5SO 4) 3 ·9H 2O, Na 3[Er(Oxydiacetate) 3]2NaClO 4·6H 2O and Er(HCOO) 3·2H 2O systems are reported. These analyses are based on a uniform model Hamiltonian that includes 20 free-ion parameters which are defined as central field ( EAVG), two-body electrostatic repulsion ( F2,4,6), two-body configuration (α, β, γ), three-body configuration ( T2,3,4,6,7,8), spin-orbit (ξ), spin-other-orbit ( M0,2,4) and electrostatically correlated spin-orbit ( P2,4,6) interactions. The systematic theoretical analysis of crystal free-ion levels results in a good correlation between calculated and observed energies. For example, comparison between the observed and calculated crystal free-ion levels of 13(Er:GdAlO 3), 8(Er:YVO 4), 8(Er:LuPO 4) and 11(Er:ErES) yields RMS deviations of 12 cm -1, 2 cm -1, 4 cm -1 and 7 cm -1 respectively. The empirical crystal free-ion energy parameters derived from fitting experimental data with the model Hamiltonian are consistent. The effects of the crystalline hosts on the empirical parameters are examined.

  16. 58 mJ burst containing ultra-short pulses with homogenous energy level from an Yb-doped fiber amplifier

    NASA Astrophysics Data System (ADS)

    Breitkopf, Sven; Klenke, Arno; Gottschall, Thomas; Otto, Hans-Jürgen; Jauregui, Cesar; Limpert, Jens; Tünnermann, Andreas

    2013-03-01

    There is a great interest in obtaining laser pulses with a high average power as well as high pulse energies. Continuously pulsed systems face many problems to satisfy those requirements, independent on the amplifier concept. While many applications such as electron beam characterization and free-electron-laser seeding need high pulse energies at high repetition rates, they only need those laser pulses for a certain amount of time. Therefore, it is not necessary to run a laser system with continuous pulses at those parameters and a so-called burst mode might be sufficient and even essential in such cases. We report on a CPA-laser system, based on a large pitch fiber as a main-amplifier delivering bursts containing ultra-short, highly-energetic pulses. The burst rate is set to 20Hz, while each burst contains 2000 pulses at a pulse-repetition-rate of 10MHz and with a pulse-duration of 700fs. Hence the duty cycle D is 0.4%. To achieve a homogeneous pulse energy level between 27μJ and 31μJ after the compression, the main amplifier is pumped with a very high power of 1.6kW in a burst-mode (D=10%). By using an acousto-optical modulator (AOM) after the main-amp fiber, the residual output before and after the burst is removed to suppress ASE and any underground-pulses around the amplified burst. The limitations that could be observed during this experiment were mainly due to mode instabilities, which were detectable even on a very short time scale of a few hundred μs using a high speed camera.

  17. Aluminum doping tunes band gap energy level as well as oxidative stress-mediated cytotoxicity of ZnO nanoparticles in MCF-7 cells

    NASA Astrophysics Data System (ADS)

    Akhtar, Mohd Javed; Alhadlaq, Hisham A.; Alshamsan, Aws; Majeed Khan, M. A.; Ahamed, Maqusood

    2015-09-01

    We investigated whether Aluminum (Al) doping tunes band gap energy level as well as selective cytotoxicity of ZnO nanoparticles in human breast cancer cells (MCF-7). Pure and Al-doped ZnO nanoparticles were prepared by a simple sol-gel method. Characterization study confirmed the formation of single phase of AlxZn1-xO nanocrystals with the size range of 33-55 nm. Al-doping increased the band gap energy of ZnO nanoparticles (from 3.51 eV for pure to 3.87 eV for Al-doped ZnO). Al-doping also enhanced the cytotoxicity and oxidative stress response of ZnO nanoparticles in MCF-7 cells. The IC50 for undoped ZnO nanoparticles was 44 μg/ml while for the Al-doped ZnO counterparts was 31 μg/ml. Up-regulation of apoptotic genes (e.g. p53, bax/bcl2 ratio, caspase-3 & caspase-9) along with loss of mitochondrial membrane potential suggested that Al-doped ZnO nanoparticles induced apoptosis in MCF-7 cells through mitochondrial pathway. Importantly, Al-doping did not change the benign nature of ZnO nanoparticles towards normal cells suggesting that Al-doping improves the selective cytotoxicity of ZnO nanoparticles toward MCF-7 cells without affecting the normal cells. Our results indicated a novel approach through which the inherent selective cytotoxicity of ZnO nanoparticles against cancer cells can be further improved.

  18. Quantum and classical dynamics of H + CaCl(X (2)Σ(+)) → HCl + Ca((1)S) reaction and vibrational energy levels of the HCaCl complex.

    PubMed

    Tan, Rui Shan; Zhai, Huan Chen; Gao, Feng; Tong, Dianmin; Lin, Shi Ying

    2016-06-21

    We carried out accurate quantum wave packet as well as quasi-classical trajectory (QCT) calculations for H + CaCl (νi = 0, ji = 0) reaction occurring on an adiabatic ground state using the recent ab initio potential energy surface to obtain the quantum and QCT reaction probabilities for several partial waves (J = 0, 10, and 20) as well as state resolved QCT integral and differential cross sections. The complete list of vibrational energy levels supported by the intermediate HCaCl complex is also obtained using the Lanczos algorithm. The QCT reaction probabilities show excellent agreement with the quantum ones except for the failure in reproducing the highly oscillatory resonance structure. Despite the fact that the reaction is exothermic and the existence of a barrier that is energetically lower than the bottom of the reactant valley, the reaction probability for J = 0 shows threshold-like behavior and the reactivity all through the energies is very low (<0.1). The dynamical features at two different energy regions (<0.35 eV and >0.35 eV) are found to be different drastically from each other. The analyses of these results suggest that the reaction is governed by one of the two different types of reaction mechanism, one is the direct mechanism at the high energy region and the other is the indirect mechanism at the low energy region by which the reaction proceeds through the long-lived intermediate complex followed by a statistical dissociation into asymptotic channels. PMID:27224034

  19. Aluminum doping tunes band gap energy level as well as oxidative stress-mediated cytotoxicity of ZnO nanoparticles in MCF-7 cells.

    PubMed

    Akhtar, Mohd Javed; Alhadlaq, Hisham A; Alshamsan, Aws; Majeed Khan, M A; Ahamed, Maqusood

    2015-01-01

    We investigated whether Aluminum (Al) doping tunes band gap energy level as well as selective cytotoxicity of ZnO nanoparticles in human breast cancer cells (MCF-7). Pure and Al-doped ZnO nanoparticles were prepared by a simple sol-gel method. Characterization study confirmed the formation of single phase of Al(x)Zn(1-x)O nanocrystals with the size range of 33-55 nm. Al-doping increased the band gap energy of ZnO nanoparticles (from 3.51 eV for pure to 3.87 eV for Al-doped ZnO). Al-doping also enhanced the cytotoxicity and oxidative stress response of ZnO nanoparticles in MCF-7 cells. The IC50 for undoped ZnO nanoparticles was 44 μg/ml while for the Al-doped ZnO counterparts was 31 μg/ml. Up-regulation of apoptotic genes (e.g. p53, bax/bcl2 ratio, caspase-3 &caspase-9) along with loss of mitochondrial membrane potential suggested that Al-doped ZnO nanoparticles induced apoptosis in MCF-7 cells through mitochondrial pathway. Importantly, Al-doping did not change the benign nature of ZnO nanoparticles towards normal cells suggesting that Al-doping improves the selective cytotoxicity of ZnO nanoparticles toward MCF-7 cells without affecting the normal cells. Our results indicated a novel approach through which the inherent selective cytotoxicity of ZnO nanoparticles against cancer cells can be further improved. PMID:26347142

  20. Aluminum doping tunes band gap energy level as well as oxidative stress-mediated cytotoxicity of ZnO nanoparticles in MCF-7 cells

    PubMed Central

    Akhtar, Mohd Javed; Alhadlaq, Hisham A.; Alshamsan, Aws; Majeed Khan, M.A.; Ahamed, Maqusood

    2015-01-01

    We investigated whether Aluminum (Al) doping tunes band gap energy level as well as selective cytotoxicity of ZnO nanoparticles in human breast cancer cells (MCF-7). Pure and Al-doped ZnO nanoparticles were prepared by a simple sol-gel method. Characterization study confirmed the formation of single phase of AlxZn1-xO nanocrystals with the size range of 33–55 nm. Al-doping increased the band gap energy of ZnO nanoparticles (from 3.51 eV for pure to 3.87 eV for Al-doped ZnO). Al-doping also enhanced the cytotoxicity and oxidative stress response of ZnO nanoparticles in MCF-7 cells. The IC50 for undoped ZnO nanoparticles was 44 μg/ml while for the Al-doped ZnO counterparts was 31 μg/ml. Up-regulation of apoptotic genes (e.g. p53, bax/bcl2 ratio, caspase-3 & caspase-9) along with loss of mitochondrial membrane potential suggested that Al-doped ZnO nanoparticles induced apoptosis in MCF-7 cells through mitochondrial pathway. Importantly, Al-doping did not change the benign nature of ZnO nanoparticles towards normal cells suggesting that Al-doping improves the selective cytotoxicity of ZnO nanoparticles toward MCF-7 cells without affecting the normal cells. Our results indicated a novel approach through which the inherent selective cytotoxicity of ZnO nanoparticles against cancer cells can be further improved. PMID:26347142

  1. Energy level of the Si-related DX-center in (Al{sub y}Ga{sub 1−y}){sub 1−x}In{sub x}As

    SciTech Connect

    Heckelmann, Stefan Lackner, David; Bett, Andreas W.

    2015-03-09

    For the quaternary material (Al{sub y}Ga{sub 1−y}){sub 1−x}In{sub x}As, the energy level of the silicon-related deep electron trap known as the DX-center is calculated. In addition, the composition range y(x) is derived, for which the silicon-related DX-center level is below the conduction band minimum and thus electronically active. Eventually, the result of the calculation is compared with available measurement data, revealing good agreement regarding the composition when the DX-center energy level crosses the conduction band minimum.

  2. Tension density as counter force to the Lorentz force density

    NASA Astrophysics Data System (ADS)

    Nozaki, Hiroo; Senami, Masato; Ichikawa, Kazuhide; Tachibana, Akitomo

    2016-08-01

    It is confirmed numerically that the tension density defined in quantum field theory is the counter force to the Lorentz force density. We take benzenedithiol in a nonequilibrium steady state as an example for the numerical demonstration of the balance between these densities. While we use simply a nonequilibrium Green’s function method for a quantum conduction state instead of computations based on quantum field theory, the balance between the tension density and the Lorentz force density can be confirmed. The tension density is free from the relaxation time ansatz and defined as a local quantity. The tension density may give a novel viewpoint to the understanding of the physics of electrical conduction.

  3. Optical Density Chart

    NASA Technical Reports Server (NTRS)

    2003-01-01

    ProVision Technologies, a NASA research partnership center at Sternis Space Center in Mississippi, has developed a new hyperspectral imaging (HSI) system that is much smaller than the original large units used aboard remote sensing aircraft and satellites. The new apparatus is about the size of a breadbox. HSI may be useful to ophthalmologists to study and diagnose eye health, both on Earth and in space, by examining the back of the eye to determine oxygen and blood flow quickly and without any invasion. ProVision's hyperspectral imaging system can scan the human eye and produce a graph showing optical density or light absorption, which can then be compared to a graph from a normal eye. Scans of the macula, optic disk or optic nerve head, and blood vessels can be used to detect anomalies and identify diseases in this delicate and important organ. ProVision has already developed a relationship with the University of Alabama at Birmingham, but is still on the lookout for a commercial partner in this application.

  4. High Energy Density Microwaves

    SciTech Connect

    Phillips, R.M.

    1999-04-01

    These proceedings represent papers presented at the RF98 Workshop entitled `High Energy Density Microwaves` held in California in October, 1998. The topics discussed were predominantly accelerator{minus}related. The Workshop dealt, for the most part, with the generation and control of electron beams, the amplification of RF signals, the design of mode converters, and the effect of very high RF field gradients. This Workshop was designed to address the concerns of the microwave tube industry worldwide, the plasma physicists who deal with very high beam currents and gigawatts of RF power, and researchers in accelerator centers around the world. Papers were presented on multibeam klystrons, gyrotron development, plasmas in microwave tubes, RF breakdown, and alternatives to conventional linear coliders at 1 TeV and above. The Workshop was partially sponsored by the US Department of Energy. There were 46 papers presented at the conference,out of which 19 have been abstracted for the Energy,Science and Technology database.(AIP)

  5. Simulated Ionian Column Densities

    NASA Astrophysics Data System (ADS)

    Walker, Andrew C.; Goldstein, D. B.; Varghese, P. L.; Trafton, L. M.; Moore, C. H.

    2010-10-01

    The sublimation atmosphere of Io is modeled using the direct simulation Monte Carlo (DSMC) method. These three-dimensional simulations improve upon previous work by implementing a more accurate two-component surface temperature model. This surface temperature model solves the one-dimensional heat conduction equation with depth for every 1° by 1° surface element. It also includes the following physics: Jovian eclipse, reflected sunlight from Jupiter, latent heat of sublimation/condensation, hot spots, endogenic heating, and independent thermal inertias and albedos for the frost and non-frost surfaces. These simulations model only the dominant dayside atmospheric species, SO2. The non-equilibrium rotational and vibrational energy states of SO2 are treated as well as photo-emission from those states. Plasma heating of the atmosphere by high energy ions and electrons from the Jovian plasma torus is also modeled via a plasma energy flux. Resulting column densities are compared to recent observations in an attempt to constrain the thermal parameters for the frost and non-frost surfaces.

  6. Carbon nanotube growth density control

    NASA Technical Reports Server (NTRS)

    Delzeit, Lance D. (Inventor); Schipper, John F. (Inventor)

    2010-01-01

    Method and system for combined coarse scale control and fine scale control of growth density of a carbon nanotube (CNT) array on a substrate, using a selected electrical field adjacent to a substrate surface for coarse scale density control (by one or more orders of magnitude) and a selected CNT growth temperature range for fine scale density control (by multiplicative factors of less than an order of magnitude) of CNT growth density. Two spaced apart regions on a substrate may have different CNT growth densities and/or may use different feed gases for CNT growth.

  7. Effects of emission layer doping on the spatial distribution of charge and host recombination rate density in organic light emitting devices: A numerical study

    SciTech Connect

    Li, Yanli; Zhou, Maoqing; Zheng, Tingcai; Yao, Bo; Peng, Yingquan

    2013-12-28

    Based on drift-diffusion theory, a numerical model of the doping of a single energy level trap in the emission layer of an organic light emitting device (OLED) was developed, and the effects of doping of this single energy level trap on the distribution of the charge density, the recombination rate density, and the electric field in single- and double-layer OLEDs were studied numerically. The results show that by doping the n-type (p-type) emission layer with single energy electron (hole) traps, the distribution of the recombination rate density can be tuned and shifted, which is useful for improvement of the device performance by reduced electrode quenching or for realization of desirable special functions, e.g., emission spectrum tuning in multiple dye-doped white OLEDs.

  8. Entrainment across density interfaces

    NASA Astrophysics Data System (ADS)

    Sanchez, M. A.; Carrillo, A.; Mahjoub, O. B.

    2010-05-01

    The structure of non-homogeneous turbulence affected by stratification and rotation is investigated both by means of laboratory and numerical experiments. The experiments investigate zero mean flow across a stably stratified density interface and are used to quantify the entrainment, the mixing efficiency and different types of dominant instability and the topological aspects of the turbulent cascades detected both horizontally and vertically [1,2]. Grid turbulence in a rotating stratified two layer system is measured with PIV as well as with sonic velocimetry. Observations of the horizontal and vertical velocity energy spectra as well as the structure functions are used to estimate local mixedness, entrainment and intermittency [3,4]. The method of estimation of the average eddy diffusivity from the time series images of a sharp density interface marked by fluoresceine also take anisotropy into account. but on the long run, horizontal ( and 2D type flow such as [5]) flow directions will average out so using a single integral length scale defined in Sanchez and Redondo(1998) varying in height will be enough together with the internal frequency. The method of calculating vertical fluxes in time allows to estimate different intermittency parameters as a function of local instability e.g. Kelvin/Helmholtz, Rayleigh-Taylor or Holbmoe[6-8]. Different concentration interfaces show different fractal dimensions, that are also a power function of the local Richardson number, this may be due to different levels of intermittency and thus different spectra, which are not necessarily inertial nor in equilibrium [8,9]. [1] Sanchez M.A. and Redondo J.M.Observations from Grid Stirred Turbulence. Applied Scientific Research 59, 191-204. 1998. [2] Redondo, J.M. and Cantalapiedra I.R. Mixing in Horizontally Heterogeneous Flows . Jour. Flow Turbulence and Combustion. 51, 217-222. 1993. [3] Castilla R, Redondo J.M., Gamez P.J., Babiano A. Coherent vortices and Lagrangian Dynamics in 2D

  9. Torsional energy levels of CH{sub 3}OH{sup +}/CH{sub 3}OD{sup +}/CD{sub 3}OD{sup +} studied by zero-kinetic energy photoelectron spectroscopy and theoretical calculations

    SciTech Connect

    Dai, Zuyang; Gao, Shuming; Wang, Jia; Mo, Yuxiang

    2014-10-14

    The torsional energy levels of CH{sub 3}OH{sup +}, CH{sub 3}OD{sup +}, and CD{sub 3}OD{sup +} have been determined for the first time using one-photon zero kinetic energy photoelectron spectroscopy. The adiabatic ionization energies for CH{sub 3}OH, CH{sub 3}OD, and CD{sub 3}OD are determined as 10.8396, 10.8455, and 10.8732 eV with uncertainties of 0.0005 eV, respectively. Theoretical calculations have also been performed to obtain the torsional energy levels for the three isotopologues using a one-dimensional model with approximate zero-point energy corrections of the torsional potential energy curves. The calculated values are in good agreement with the experimental data. The barrier height of the torsional potential energy without zero-point energy correction was calculated as 157 cm{sup −1}, which is about half of that of the neutral (340 cm{sup −1}). The calculations showed that the cation has eclipsed conformation at the energy minimum and staggered one at the saddle point, which is the opposite of what is observed in the neutral molecule. The fundamental C–O stretch vibrational energy level for CD{sub 3}OD{sup +} has also been determined. The energy levels for the combinational excitation of the torsional vibration and the fundamental C–O stretch vibration indicate a strong torsion-vibration coupling.

  10. Characterization of heterojunctions via x-ray and uv photoemission spectroscopy: energy level implications for single and mixed monolayer SAMs, cadmium selenide nanoparticle films, and organic semiconductor depositions

    NASA Astrophysics Data System (ADS)

    Graham, Amy L.

    transfer states of ZnPc did not favor energy level alignment on the SAM/Au substrates used; C60 demonstrated vacuum level shifts on C15 and C12ph alkanethiol monolayers consistent with the interface charge transfer (ICT) model. These results provide credibility to models recently demonstrated in the literature for other passivated metal surfaces, and include the viability of SAMs in these discussions.

  11. Comparison of density determination of liquid samples by density meters

    NASA Astrophysics Data System (ADS)

    Buchner, C.; Wolf, H.; Vámossy, C.; Lorefice, S.; Lenard, E.; Spohr, I.; Mares, G.; Perkin, M.; Parlic-Risovic, T.; Grue, L.-L.; Tammik, K.; van Andel, I.; Zelenka, Z.

    2016-01-01

    Hydrostatic density determinations of liquids as reference material are mainly performed by National Metrology Institutes to provide means for calibrating or checking liquid density measuring instruments such as oscillation-type density meters. These density meters are used by most of the metrology institutes for their calibration and scientific work. The aim of this project was to compare the results of the liquid density determination by oscillating density meters of the participating laboratories. The results were linked to CCM.D.K-2 partly via Project EURAMET.M.D.K-2 (1019) "Comparison of liquid density standards" by hydrostatic weighing piloted by BEV in 2008. In this comparison pentadecane, water and of oil with a high viscosity were measured at atmospheric pressure using oscillation type density meter. The temperature range was from 15 °C to 40 °C. The measurement results were in some cases discrepant. Further studies, comparisons are essential to explore the capability and uncertainty of the density meters Main text To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

  12. NASA Ames's electric arc-driven shock tube facility and research on nonequilibrium phenomena in low density hypersonic flows

    NASA Technical Reports Server (NTRS)

    Sharma, Surendra P.

    1992-01-01

    Basic requirements for a ground test facility simulating low density hypersonic flows are discussed. Such facilities should be able to produce shock velocities in the range of 10-17 km/sec in an initial pressure of 0.010 to 0.050 Torr. The facility should be equipped with diagnostics systems to be able to measure the emitted radiation, characteristic temperatures and populations in various energy levels. In the light of these requirements, NASA Ames's electric arc-driven low density shock tube facility is described and available experimental diagnostics systems and computational tools are discussed.

  13. High Power Density Motors

    NASA Technical Reports Server (NTRS)

    Kascak, Daniel J.

    2004-01-01

    With the growing concerns of global warming, the need for pollution-free vehicles is ever increasing. Pollution-free flight is one of NASA's goals for the 21" Century. , One method of approaching that goal is hydrogen-fueled aircraft that use fuel cells or turbo- generators to develop electric power that can drive electric motors that turn the aircraft's propulsive fans or propellers. Hydrogen fuel would likely be carried as a liquid, stored in tanks at its boiling point of 20.5 K (-422.5 F). Conventional electric motors, however, are far too heavy (for a given horsepower) to use on aircraft. Fortunately the liquid hydrogen fuel can provide essentially free refrigeration that can be used to cool the windings of motors before the hydrogen is used for fuel. Either High Temperature Superconductors (HTS) or high purity metals such as copper or aluminum may be used in the motor windings. Superconductors have essentially zero electrical resistance to steady current. The electrical resistance of high purity aluminum or copper near liquid hydrogen temperature can be l/lOO* or less of the room temperature resistance. These conductors could provide higher motor efficiency than normal room-temperature motors achieve. But much more importantly, these conductors can carry ten to a hundred times more current than copper conductors do in normal motors operating at room temperature. This is a consequence of the low electrical resistance and of good heat transfer coefficients in boiling LH2. Thus the conductors can produce higher magnetic field strengths and consequently higher motor torque and power. Designs, analysis and actual cryogenic motor tests show that such cryogenic motors could produce three or more times as much power per unit weight as turbine engines can, whereas conventional motors produce only 1/5 as much power per weight as turbine engines. This summer work has been done with Litz wire to maximize the current density. The current is limited by the amount of heat it

  14. Optical spectra, energy levels and crystal-field analysis of Sm3 in Na3[Sm(oxydiacetate)3] · 2NaClO4 · 6H2O

    NASA Astrophysics Data System (ADS)

    May, P. Stanley; Reid, Michael F.; Richardson, F. S.

    Locations and assignments of 144 crystal-field energy levels are reported for Sm3+ in the trigonal Na3[Sm(oxydiacetate)3] · 2NaClO4 · 6H2O system. These energy levels span the 0-36 000 cm-1 energy region, and they were located and assigned from optical emission spectra and from axial and orthoaxial (σ- and π-polarized) absorption measurements on single crystals. The principal SL parentages of the assigned levels span at least 20 Russell-Saunders terms within the 4f5 electronic configuration of Sm3+, and these assigned levels represent nearly half the total number of crystal-field energy levels predicted to occur within the 0-36 000 cm-1 region. The assigned levels are analysed in terms of a 26-parameter electronic hamiltonian in which six of the parameters are defined to represent the 4f-electron/crystal-field interactions for Sm3+ located at sites with trigonal dihedral (D3) symmetry. Of the 26 parameters, 22 (including the six crystal-field parameters) are used in fitting calculated energy levels to the experimental data, and excellent calculated-versus-experimental energy level fits are achieved. Fitted values obtained in this study for the Sm3+ 'free-ion' energy parameters are compared to those reported previously for Sm3+ in LaF3 and LaCl3. Quantitatively determined line strengths are reported for 50 (4f → 4f) crystal-field transitions observed in the single-crystal absorption spectra of Na3[Sm(oxydiacetate)3] · 2NaClO4 · 6H2O at 10 K.

  15. Optical-absorption spectra, crystal-field energy levels, and transition line strengths of holmium in trigonal Na3[Ho(C4H4O5)3].2NaClO4.6H2O

    NASA Astrophysics Data System (ADS)

    Moran, D. M.; de Piante, Anne; Richardson, F. S.

    1990-08-01

    Locations and assignments of 105 crystal-field levels are reported for Ho3+ in the trigonal Na3[Ho(oxydiacetate)3].2NaClO4.6H2O system. These levels were located and assigned from transitions observed in axial and σ- and π-polarized orthoaxial absorption spectra obtained on single-crystal samples at temperatures between 5 and 295 K. The absorption measurements spanned the 8000-37 000-cm-1 spectral region, and the assigned energy levels derive from 23 different [SL]J multiplet manifolds of the 4f10 electronic configuration of Ho3+, with principal SL parentages derived from nine different Russell-Saunders terms (5I, 5F, 5S, 3K, 5G,3H, 3L, 3M, and 5D). The empirical energy-level data are analyzed in terms of a parametrized model Hamiltonian for the 4f10 electronic configuration, assumed to be perturbed by a crystal field of trigonal dihedral (D3) symmetry. Parametric fits of calculated-to-empirical energy-level data yield a rms deviation of ~9 cm-1 (between calculated and observed energies). The Hamiltonian parameter values obtained from these energy-level analyses are compared with results obtained from similar analyses of Ho3+ in other crystals and of other lanthanide (M3+) ions in the Na3[M(oxydiacetate)3].2NaClO4.6H2O system. In addition to energy-level locations and assignments, quantitatively determined line strengths are reported for 42 transitions observed in the axial absorption spectra at 10 K, and for 19 transitions observed in the π-polarized orthoaxial absorption spectra at 10 K. Fifty of these transitions originate from the ground crystal-field level of the 5I8 (ground) multiplet, and eleven originate from the second crystal-field level (located 14 cm-1 above ground) of 5I8.

  16. Spectral density of Cooper pairs in two level quantum dot-superconductors Josephson junction

    NASA Astrophysics Data System (ADS)

    Dhyani, A.; Rawat, P. S.; Tewari, B. S.

    2016-09-01

    In the present paper, we report the role of quantum dot energy levels on the electronic spectral density for a two level quantum dot coupled to s-wave superconducting leads. The theoretical arguments in this work are based on the Anderson model so that it necessarily includes dot energies, single particle tunneling and superconducting order parameter for BCS superconductors. The expression for single particle spectral function is obtained by using the Green's function equation of motion technique. On the basis of numerical computation of spectral function of superconducting leads, it has been found that the charge transfer across such junctions can be controlled by the positions and availability of the dot levels.

  17. Hybrid density functional study of oligothiophene/ZnO interface for photovoltaics

    SciTech Connect

    Sai, Na; Leung, Kevin; Chelikowsky, James R.

    2011-03-21

    Organic-inorganic donor-acceptor interfaces are gaining growing attention in organic photovoltaic applications as each component of the interface offers unique attributes. Here we use hybrid density functional theory to examine the electronic structure of sexithiophene/ZnO interfaces. We find that interfacial molecular orientations strongly influence the adsorption energy, the energy level alignment, and the open-circuit voltage. We attribute the orientation dependence to the varied strength of electronic coupling between the molecule and the substrate. Our study suggests that photovoltaic performance can be optimized by controlling the interfacial design of molecular orientations.

  18. Density Fluctuations in Liquid Water

    NASA Astrophysics Data System (ADS)

    English, Niall J.; Tse, John S.

    2011-01-01

    The density distributions and fluctuations in grids of varying size in liquid water at ambient pressure, both above the freezing point and in the supercooled state, are analyzed from the trajectories obtained from large-scale molecular dynamics simulations. It is found that the occurrence of low- and high-density regions (LDL and HDL) is transient and their respective residence times are dependent on the size of the simulated system. The spatial extent of density-density correlation is found to be within 7 Å or less. The temporal existence of LDL and HDL arises as a result of natural density fluctuations of an equilibrium system. The density of bulk water at ambient conditions is homogenous.

  19. Symmetry energy, its density slope, and neutron-proton effective mass splitting at normal density extracted from global nucleon optical potentials

    SciTech Connect

    Xu Chang; Li Baoan; Chen Liewen

    2010-11-15

    Based on the Hugenholtz-Van Hove theorem, it is shown that both the symmetry energy E{sub sym}({rho}) and its density slope L({rho}) at normal density {rho}{sub 0} are completely determined by the nucleon global optical potentials. The latter can be extracted directly from nucleon-nucleus scatterings, (p,n) charge-exchange reactions, and single-particle energy levels of bound states. Averaging all phenomenological isovector nucleon potentials constrained by world data available in the literature since 1969, the best estimates of E{sub sym}({rho}{sub 0})=31.3 MeV and L({rho}{sub 0})=52.7 MeV are simultaneously obtained. Moreover, the corresponding neutron-proton effective mass splitting in neutron-rich matter of isospin asymmetry {delta} is estimated to be (m{sub n}{sup *}-m{sub p}{sup *})/m=0.32{delta}.

  20. Density waves in granular flow

    NASA Astrophysics Data System (ADS)

    Herrmann, H. J.; Flekkøy, E.; Nagel, K.; Peng, G.; Ristow, G.

    Ample experimental evidence has shown the existence of spontaneous density waves in granular material flowing through pipes or hoppers. Using Molecular Dynamics Simulations we show that several types of waves exist and find that these density fluctuations follow a 1/f spectrum. We compare this behaviour to deterministic one-dimensional traffic models. If positions and velocities are continuous variables the model shows self-organized criticality driven by the slowest car. We also present Lattice Gas and Boltzmann Lattice Models which reproduce the experimentally observed effects. Density waves are spontaneously generated when the viscosity has a nonlinear dependence on density which characterizes granular flow.

  1. Density Estimation with Mercer Kernels

    NASA Technical Reports Server (NTRS)

    Macready, William G.

    2003-01-01

    We present a new method for density estimation based on Mercer kernels. The density estimate can be understood as the density induced on a data manifold by a mixture of Gaussians fit in a feature space. As is usual, the feature space and data manifold are defined with any suitable positive-definite kernel function. We modify the standard EM algorithm for mixtures of Gaussians to infer the parameters of the density. One benefit of the approach is it's conceptual simplicity, and uniform applicability over many different types of data. Preliminary results are presented for a number of simple problems.

  2. Density of the lunar interior.

    NASA Technical Reports Server (NTRS)

    Gast, P. W.; Giuli, R. T.

    1972-01-01

    It is attempted to derive the constraints that can be placed on the density of the lunar interior. The moment of inertia of the moon and its mean density are being considered in the investigation together with the mass and density of the lunar crust that have been inferred from the seismic refraction data recorded by the passive seismometer. The calculations presented show that the density of the lunar interior can easily approach values as high as 3.5 for a fraction of the lunar mass which lies in the range from 1/2 to 2/3.

  3. SOP - Determination of Requirement Density

    SciTech Connect

    Reynolds, John G.; Martz, Jr., Harry E.

    2010-10-26

    The purpose of this Standard Operating Procedure (SOP) is to give guidelines on how to determine the density of a sample that will be used as the requirement density. This will be the requirement density of record for the specimens examined by Micro CT and EDS measurements. This density will then be set as the formulation requirement for radiography measurements. This SOP is referred to in TP 48— Preparation of Hydrogen Peroxide/Icing Sugar Specimens for X-ray Measurements by J. G. Reynolds and H. E. Martz.

  4. Level densities of heaviest nuclei

    NASA Astrophysics Data System (ADS)

    Bezbakh, A. N.; Shneidman, T. M.; Adamian, G. G.; Antonenko, N. V.

    2014-06-01

    The intrinsic level densities of superheavy nuclei in the α-decay chains of 296,298,300120 are calculated using the single-particle spectra obtained with the modified two-center shell model. The role of the shell and pairing effects on the level density as well as their quenching with excitation energy are studied. The extracted level density parameter is expressed as a function of mass number, ground-state shell correction, and excitation energy. The results are compared with the phenomenological values of level density parameters used to calculate the survival of excited heavy nuclei.

  5. Canonical density matrix perturbation theory.

    PubMed

    Niklasson, Anders M N; Cawkwell, M J; Rubensson, Emanuel H; Rudberg, Elias

    2015-12-01

    Density matrix perturbation theory [Niklasson and Challacombe, Phys. Rev. Lett. 92, 193001 (2004)] is generalized to canonical (NVT) free-energy ensembles in tight-binding, Hartree-Fock, or Kohn-Sham density-functional theory. The canonical density matrix perturbation theory can be used to calculate temperature-dependent response properties from the coupled perturbed self-consistent field equations as in density-functional perturbation theory. The method is well suited to take advantage of sparse matrix algebra to achieve linear scaling complexity in the computational cost as a function of system size for sufficiently large nonmetallic materials and metals at high temperatures. PMID:26764847

  6. Current density and state density in diluted magnetic semiconductor nanostructures

    NASA Astrophysics Data System (ADS)

    Pérez Merchancano, S. T.; Paredes Gutiérrez, H.; Zuñiga, J. A.

    2016-02-01

    We study in this paper the spin-polarized current density components in diluted magnetic semiconductor tunnelling diodes with different sample geometries. We calculate the resonant JxV and the density of states. The differential conductance curves are analyzed as functions of the applied voltage and the magnetic potential strength induced by the magnetic ions.

  7. Breast Density Analysis Using an Automatic Density Segmentation Algorithm.

    PubMed

    Oliver, Arnau; Tortajada, Meritxell; Lladó, Xavier; Freixenet, Jordi; Ganau, Sergi; Tortajada, Lidia; Vilagran, Mariona; Sentís, Melcior; Martí, Robert

    2015-10-01

    Breast density is a strong risk factor for breast cancer. In this paper, we present an automated approach for breast density segmentation in mammographic images based on a supervised pixel-based classification and using textural and morphological features. The objective of the paper is not only to show the feasibility of an automatic algorithm for breast density segmentation but also to prove its potential application to the study of breast density evolution in longitudinal studies. The database used here contains three complete screening examinations, acquired 2 years apart, of 130 different patients. The approach was validated by comparing manual expert annotations with automatically obtained estimations. Transversal analysis of the breast density analysis of craniocaudal (CC) and mediolateral oblique (MLO) views of both breasts acquired in the same study showed a correlation coefficient of ρ = 0.96 between the mammographic density percentage for left and right breasts, whereas a comparison of both mammographic views showed a correlation of ρ = 0.95. A longitudinal study of breast density confirmed the trend that dense tissue percentage decreases over time, although we noticed that the decrease in the ratio depends on the initial amount of breast density. PMID:25720749

  8. Density limits investigation and high density operation in EAST tokamak

    NASA Astrophysics Data System (ADS)

    Zheng, Xingwei; Li, Jiangang; Hu, Jiansheng; Liu, Haiqing; Jie, Yinxian; Wang, Shouxin; Li, Jiahong; Duan, Yanming; Li, Miaohui; Li, Yongchun; Zhang, Ling; Ye, Yang; Yang, Qingquan; Zhang, Tao; Cheng, Yingjie; Xu, Jichan; Wang, Liang; Xu, Liqing; Zhao, Hailin; Wang, Fudi; Lin, Shiyao; Wu, Bin; Lyu, Bo; Xu, Guosheng; Gao, Xiang; Shi, Tonghui; He, Kaiyang; Lan, Heng; Chu, Nan; Cao, Bin; Sun, Zhen; Zuo, Guizhong; Ren, Jun; Zhuang, Huidong; Li, Changzheng; Yuan, Xiaolin; Yu, Yaowei; Wang, Houyin; Chen, Yue; Wu, Jinhua; EAST Team

    2016-05-01

    Increasing the density in a tokamak is limited by the so-called density limit, which is generally performed as an appearance of disruption causing loss of plasma confinement, or a degradation of high confinement mode which could further lead to a H  →  L transition. The L-mode and H-mode density limit has been investigated in EAST tokamak. Experimental results suggest that density limits could be triggered by either edge cooling or excessive central radiation. The L-mode density limit disruption is generally triggered by edge cooling, which leads to the current profile shrinkage and then destabilizes a 2/1 tearing mode, ultimately resulting in a disruption. The L-mode density limit scaling agrees well with the Greenwald limit in EAST. The observed H-mode density limit in EAST is an operational-space limit with a value of 0.8∼ 0.9{{n}\\text{GW}} . High density H-mode heated by neutral beam injection (NBI) and lower hybrid current drive (LHCD) are analyzed, respectively. The constancy of the edge density gradients in H-mode indicates a critical limit caused perhaps by e.g. ballooning induced transport. The maximum density is accessed at the H  →  L transition which is generally caused by the excessive core radiation due to high Z impurities (Fe, Cu). Operating at a high density (>2.8× {{10}19} {{\\text{m}}-3} ) is favorable for suppressing the beam shine through NBI. High density H-mode up to 5.3× {{10}19}{{\\text{m}}-3}~≤ft(∼ 0.8{{n}\\text{GW}}\\right) could be sustained by 2 MW 4.6 GHz LHCD alone, and its current drive efficiency is studied. Statistics show that good control of impurities and recycling facilitate high density operation. With careful control of these factors, high density up to 0.93{{n}\\text{GW}} stable H-mode operation was carried out heated by 1.7 MW LHCD and 1.9 MW ion cyclotron resonance heating with supersonic molecular beam injection fueling.

  9. Generalization of the Kohn-Sham system that can represent arbitrary one-electron density matrices

    NASA Astrophysics Data System (ADS)

    van Dam, Hubertus J. J.

    2016-05-01

    Density functional theory is currently the most widely applied method in electronic structure theory. The Kohn-Sham method, based on a fictitious system of noninteracting particles, is the workhorse of the theory. The particular form of the Kohn-Sham wave function admits only idempotent one-electron density matrices whereas wave functions of correlated electrons in post-Hartree-Fock methods invariably have fractional occupation numbers. Here we show that by generalizing the orbital concept and introducing a suitable dot product as well as a probability density, a noninteracting system can be chosen that can represent the one-electron density matrix of any system, even one with fractional occupation numbers. This fictitious system ensures that the exact electron density is accessible within density functional theory. It can also serve as the basis for reduced density matrix functional theory. Moreover, to aid the analysis of the results the orbitals may be assigned energies from a mean-field Hamiltonian. This produces energy levels that are akin to Hartree-Fock orbital energies such that conventional analyses based on Koopmans' theorem are available. Finally, this system is convenient in formalisms that depend on creation and annihilation operators as they are trivially applied to single-determinant wave functions.

  10. Generalization of the Kohn-Sham system that can represent arbitrary one-electron density matrices

    DOE PAGESBeta

    Hubertus J. J. van Dam

    2016-05-23

    Density functional theory is currently the most widely applied method in electronic structure theory. The Kohn-Sham method, based on a fictitious system of noninteracting particles, is the workhorse of the theory. The particular form of the Kohn-Sham wave function admits only idempotent one-electron density matrices whereas wave functions of correlated electrons in post-Hartree-Fock methods invariably have fractional occupation numbers. Here we show that by generalizing the orbital concept and introducing a suitable dot product as well as a probability density, a noninteracting system can be chosen that can represent the one-electron density matrix of any system, even one with fractionalmore » occupation numbers. This fictitious system ensures that the exact electron density is accessible within density functional theory. It can also serve as the basis for reduced density matrix functional theory. Moreover, to aid the analysis of the results the orbitals may be assigned energies from a mean-field Hamiltonian. This produces energy levels that are akin to Hartree-Fock orbital energies such that conventional analyses based on Koopmans' theorem are available. Lastly, this system is convenient in formalisms that depend on creation and annihilation operators as they are trivially applied to single-determinant wave functions.« less

  11. FOREWORD: Special issue on density

    NASA Astrophysics Data System (ADS)

    Fujii, Kenichi

    2004-04-01

    This special issue on density was undertaken to provide readers with an overview of the present state of the density standards for solids, liquids and gases, as well as the technologies developed for measuring density. This issue also includes topics on the refractive index of gases and on techniques used for calibrating hydrometers so that almost all areas concerned with density standards are covered in four review articles and seven original articles, most of which describe current research being conducted at national metrology institutes (NMIs). A review article was invited from the Ruhr-Universität Bochum to highlight research on the magnetic suspension densimeters. In metrology, the determinations of the volume of a weight and the density of air are of primary importance in establishing a mass standard because the effect of the buoyancy force of air acting on the weight must be known accurately to determine the mass of the weight. A density standard has therefore been developed at many NMIs with a close relation to the mass standard. Hydrostatic weighing is widely used to measure the volume of a solid. The most conventional hydrostatic weighing method uses water as a primary density standard for measuring the volume of a solid. A brief history of the determination of the density of water is therefore given in a review article, as well as a recommended value for the density of water with a specified isotopic abundance. The most modern technique for hydrostatic weighing uses a solid density standard instead of water. For this purpose, optical interferometers for measuring the diameters of silicon spheres have been developed to convert the length standard into the volume standard with a small uncertainty. A review article is therefore dedicated to describing the state-of-the-art optical interferometers developed for silicon spheres. Relative combined standard uncertainties of several parts in 108 have been achieved today for measuring the volume and density of

  12. Insulin Sensitivity in Adipose and Skeletal Muscle Tissue of Dairy Cows in Response to Dietary Energy Level and 2,4-Thiazolidinedione (TZD)

    PubMed Central

    Hosseini, Afshin; Tariq, Muhammad Rizwan; Trindade da Rosa, Fernanda; Kesser, Julia; Iqbal, Zeeshan; Mora, Ofelia; Sauerwein, Helga; Drackley, James K.; Trevisi, Erminio; Loor, Juan J.

    2015-01-01

    The effects of dietary energy level and 2,4-thiazolidinedione (TZD) injection on feed intake, body fatness, blood biomarkers and TZD concentrations, genes related to insulin sensitivity in adipose tissue (AT) and skeletal muscle, and peroxisome proliferator-activated receptor gamma (PPARG) protein in subcutaneous AT (SAT) were evaluated in Holstein cows. Fourteen nonpregnant nonlactating cows were fed a control low-energy (CON, 1.30 Mcal/kg) diet to meet 100% of estimated nutrient requirements for 3 weeks, after which half of the cows were assigned to a higher-energy diet (OVE, 1.60 Mcal/kg) and half of the cows continued on CON for 6 weeks. All cows received an intravenous injection of TZD starting 2 weeks after initiation of dietary treatments and for an additional 2 weeks, which served as the washout period. Cows fed OVE had greater energy intake and body mass than CON, and TZD had no effect during the administration period. The OVE cows had greater TZD clearance rate than CON cows. The lower concentration of nonesterified fatty acids (NEFA) and greater concentration of insulin in blood of OVE cows before TZD injection indicated positive energy balance and higher insulin sensitivity. Administration of TZD increased blood concentrations of glucose, insulin, and beta-hydroxybutyrate (BHBA) at 2 to 4 weeks after diet initiation, while the concentration of NEFA and adiponectin (ADIPOQ) remained unchanged during TZD. The TZD upregulated the mRNA expression of PPARG and its targets FASN and SREBF1 in SAT, but also SUMO1 and UBC9 which encode sumoylation proteins known to down-regulate PPARG expression and curtail adipogenesis. Therefore, a post-translational response to control PPARG gene expression in SAT could be a counteregulatory mechanism to restrain adipogenesis. The OVE cows had greater expression of the insulin sensitivity-related genes IRS1, SLC2A4, INSR, SCD, INSIG1, DGAT2, and ADIPOQ in SAT. In skeletal muscle, where PPARA and its targets orchestrate

  13. Insulin Sensitivity in Adipose and Skeletal Muscle Tissue of Dairy Cows in Response to Dietary Energy Level and 2,4-Thiazolidinedione (TZD).

    PubMed

    Hosseini, Afshin; Tariq, Muhammad Rizwan; Trindade da Rosa, Fernanda; Kesser, Julia; Iqbal, Zeeshan; Mora, Ofelia; Sauerwein, Helga; Drackley, James K; Trevisi, Erminio; Loor, Juan J

    2015-01-01

    The effects of dietary energy level and 2,4-thiazolidinedione (TZD) injection on feed intake, body fatness, blood biomarkers and TZD concentrations, genes related to insulin sensitivity in adipose tissue (AT) and skeletal muscle, and peroxisome proliferator-activated receptor gamma (PPARG) protein in subcutaneous AT (SAT) were evaluated in Holstein cows. Fourteen nonpregnant nonlactating cows were fed a control low-energy (CON, 1.30 Mcal/kg) diet to meet 100% of estimated nutrient requirements for 3 weeks, after which half of the cows were assigned to a higher-energy diet (OVE, 1.60 Mcal/kg) and half of the cows continued on CON for 6 weeks. All cows received an intravenous injection of TZD starting 2 weeks after initiation of dietary treatments and for an additional 2 weeks, which served as the washout period. Cows fed OVE had greater energy intake and body mass than CON, and TZD had no effect during the administration period. The OVE cows had greater TZD clearance rate than CON cows. The lower concentration of nonesterified fatty acids (NEFA) and greater concentration of insulin in blood of OVE cows before TZD injection indicated positive energy balance and higher insulin sensitivity. Administration of TZD increased blood concentrations of glucose, insulin, and beta-hydroxybutyrate (BHBA) at 2 to 4 weeks after diet initiation, while the concentration of NEFA and adiponectin (ADIPOQ) remained unchanged during TZD. The TZD upregulated the mRNA expression of PPARG and its targets FASN and SREBF1 in SAT, but also SUMO1 and UBC9 which encode sumoylation proteins known to down-regulate PPARG expression and curtail adipogenesis. Therefore, a post-translational response to control PPARG gene expression in SAT could be a counteregulatory mechanism to restrain adipogenesis. The OVE cows had greater expression of the insulin sensitivity-related genes IRS1, SLC2A4, INSR, SCD, INSIG1, DGAT2, and ADIPOQ in SAT. In skeletal muscle, where PPARA and its targets orchestrate

  14. High energy density electrochemical cell

    NASA Technical Reports Server (NTRS)

    Byrne, J. J.; Williams, D. L.

    1970-01-01

    Primary cell has an anode of lithium, a cathode containing dihaloisocyanuric acid, and a nonaqueous electrolyte comprised of a solution of lithium perchlorate in methyl formate. It produces an energy density of 213 watt hrs/lb and can achieve a high current density.

  15. Density-orbital embedding theory

    SciTech Connect

    Gritsenko, O. V.; Visscher, L.

    2010-09-15

    In the article density-orbital embedding (DOE) theory is proposed. DOE is based on the concept of density orbital (DO), which is a generalization of the square root of the density for real functions and fractional electron numbers. The basic feature of DOE is the representation of the total supermolecular density {rho}{sub s} as the square of the sum of the DO {phi}{sub a}, which represents the active subsystem A and the square root of the frozen density {rho}{sub f} of the environment F. The correct {rho}{sub s} is obtained with {phi}{sub a} being negative in the regions in which {rho}{sub f} might exceed {rho}{sub s}. This makes it possible to obtain the correct {rho}{sub s} with a broad range of the input frozen densities {rho}{sub f} so that DOE resolves the problem of the frozen-density admissibility of the current frozen-density embedding theory. The DOE Euler equation for the DO {phi}{sub a} is derived with the characteristic embedding potential representing the effect of the environment. The DO square {phi}{sub a}{sup 2} is determined from the orbitals of the effective Kohn-Sham (KS) system. Self-consistent solution of the corresponding one-electron KS equations yields not only {phi}{sub a}{sup 2}, but also the DO {phi}{sub a} itself.

  16. The Reliability of Density Measurements.

    ERIC Educational Resources Information Center

    Crothers, Charles

    1978-01-01

    Data from a land-use study of small- and medium-sized towns in New Zealand are used to ascertain the relationship between official and effective density measures. It was found that the reliability of official measures of density is very low overall, although reliability increases with community size. (Author/RLV)

  17. Instrumentation for bone density measurement

    NASA Technical Reports Server (NTRS)

    Meharg, L. S.

    1968-01-01

    Measurement system evaluates the integrated bone density over a specific cross section of bone. A digital computer converts stored bone scan data to equivalent aluminum calibration wedge thickness, and bone density is then integrated along the scan by using the trapezoidal approximation integration formula.

  18. Detecting Density Variations and Nanovoids

    SciTech Connect

    Miller, Michael K; Longstreth-Spoor, L.; Kelton, K. F.

    2011-01-01

    A combination of simulated and experimental data has been used to investigate the size range of nanovoids that can be detected in atom probe tomography data. Simulated atom probe tomography data have revealed that nanovoids as small as 1 nm in diameter can be detected in atom probe tomography data with the use of iso-density surfaces. Iso-density surfaces may be used to quantify the size, morphology and number density of nanovoids and other variations in density in atom probe tomography data. Experimental data from an aluminum-yttrium-iron metallic glass ribbon have revealed the effectiveness of this approach. Combining iso-density surfaces with atom maps also permits the segregation of solute to the nanovoids to be investigated. Field ion microscopy and thin section atom maps have also been used to detect pores and larger voids.

  19. Chronic acceleration and brain density

    NASA Technical Reports Server (NTRS)

    Hoffman, L. F.; Smith, A. H.

    1982-01-01

    Tests carried out on rabbits show that the effect of chronic acceleration is not uniform among the various tissues studied. Although body mass is reduced by the treatment, as expected, no change is apparent in brain mass or in the density of cerebrospinal fluid. Acceleration-induced changes are encountered in tissue density, the myocardium exhibiting a transient increase followed by an exponential decrease toward a limit and the brain showing an arithmetic increase in density with continued exposure to 2.5 G. The data are seen as suggesting that a specific brain load is not a regulated phenomenon and that no physiological processes occur to attenuate the increased load imposed by the hyperdynamic environment. An equation is derived indicating that the stimulus potential per unit of brain load increases with body size, even though brain density decreases and cerebrospinal fluid density increases.

  20. Attractor comparisons based on density

    SciTech Connect

    Carroll, T. L.

    2015-01-15

    Recognizing a chaotic attractor can be seen as a problem in pattern recognition. Some feature vector must be extracted from the attractor and used to compare to other attractors. The field of machine learning has many methods for extracting feature vectors, including clustering methods, decision trees, support vector machines, and many others. In this work, feature vectors are created by representing the attractor as a density in phase space and creating polynomials based on this density. Density is useful in itself because it is a one dimensional function of phase space position, but representing an attractor as a density is also a way to reduce the size of a large data set before analyzing it with graph theory methods, which can be computationally intensive. The density computation in this paper is also fast to execute. In this paper, as a demonstration of the usefulness of density, the density is used directly to construct phase space polynomials for comparing attractors. Comparisons between attractors could be useful for tracking changes in an experiment when the underlying equations are too complicated for vector field modeling.

  1. Accurate ab Initio Spin Densities

    PubMed Central

    2012-01-01

    We present an approach for the calculation of spin density distributions for molecules that require very large active spaces for a qualitatively correct description of their electronic structure. Our approach is based on the density-matrix renormalization group (DMRG) algorithm to calculate the spin density matrix elements as a basic quantity for the spatially resolved spin density distribution. The spin density matrix elements are directly determined from the second-quantized elementary operators optimized by the DMRG algorithm. As an analytic convergence criterion for the spin density distribution, we employ our recently developed sampling-reconstruction scheme [J. Chem. Phys.2011, 134, 224101] to build an accurate complete-active-space configuration-interaction (CASCI) wave function from the optimized matrix product states. The spin density matrix elements can then also be determined as an expectation value employing the reconstructed wave function expansion. Furthermore, the explicit reconstruction of a CASCI-type wave function provides insight into chemically interesting features of the molecule under study such as the distribution of α and β electrons in terms of Slater determinants, CI coefficients, and natural orbitals. The methodology is applied to an iron nitrosyl complex which we have identified as a challenging system for standard approaches [J. Chem. Theory Comput.2011, 7, 2740]. PMID:22707921

  2. Densely-packed ZnTPPs Monolayer on the Rutile TiO2(110)-(1×1) Surface: Adsorption Behavior and Energy Level Alignment

    PubMed Central

    Rangan, Sylvie; Ruggieri, Charles; Bartynski, Robert; Martínez, José Ignacio; Flores, Fernando; Ortega, José

    2016-01-01

    The adsorption of a densely packed Zinc(II) tetraphenylporphyrin monolayer on a rutile TiO2(110)-(1×1) surface has been studied using a combination of experimental and theoretical methods, aimed at analyzing the relation between adsorption behavior and barrier height formation. The adsorption configuration of ZnTPP was determined from scanning tunnel microscopy (STM) imaging, density functional theory (DFT) calculations and STM image simulation. The corresponding energy alignment was experimentally determined from X-ray and UV-photoemission spectroscopies and inverse photoemission spectroscopy. These results were found in good agreement with an appropriately corrected DFT model, pointing to the importance of local bonding and intermolecular interactions in the establishment of barrier heights. PMID:26998188

  3. Phenomenological Relativistic Energy Density Functionals

    SciTech Connect

    Lalazissis, G. A.; Kartzikos, S.; Niksic, T.; Paar, N.; Vretenar, D.; Ring, P.

    2009-08-26

    The framework of relativistic nuclear energy density functionals is applied to the description of a variety of nuclear structure phenomena, not only in spherical and deformed nuclei along the valley of beta-stability, but also in exotic systems with extreme isospin values and close to the particle drip-lines. Dynamical aspects of exotic nuclear structure is explored using the fully consistent quasiparticle random-phase approximation based on the relativistic Hartree-Bogoliubov model. Recent applications of energy density functionals with explicit density dependence of the meson-nucleon couplings are presented.

  4. Density of very small meteoroids

    NASA Astrophysics Data System (ADS)

    Kikwaya Eluo, Jean-Baptiste

    2015-08-01

    Knowing the density of meteoroids helps to determine the physical structure and gives insight into the composition of their parent bodies. The density of meteoroids can provide clues to their origins, whether cometary or asteroidal. Density helps also to characterize the risk meteoroids may pose to artificial satellites.Ceplecha (1968) calculated the density of small meteoroids based on a parameter KB (meteoroid beginning height) and classified them in four categories (A,B,C,D) with densities going from 2700 to 180 kgm-3.Babadzhanov(2002) applied a model based on quasi-continuous fragmentation (QCF) on 413 photographic Super-Schmidt meteors by solely fitting their light curves. Their densities range from 400 to 7800 kgm-3. Bellot Rubio et al. (2002) analyzed the same 413 photographic meteors assuming the single body theory based on meteoroid dynamical properties and found densities ranging from 400 to 4800 kgm-3. A thermal erosion model was used by Borovicka et al. (2007) to analyze, simultaneously, the observed decelerations and light curves of six Draconid meteors. The density was found to be 300 kgm-3, consistent with the fact that the Draconid meteors are porous aggregates of grains associated with the Jupiter-family-comet 21P/Giacobini-Zinner (Jacchia, L.G., 1950).We used the Campbell-Brown and Koschny (2004) model of meteoroid ablation to determine the density of faint meteoroids from the analysis of both observed decelerations and light curves of meteoroids (Kikwaya et al., 2009; Kikwaya et al., 2011). Our work was based on a collection of six and ninety-two sporadic meteors. The grain masses used in the modeling ranged from 10-12 Kg to 10-9 Kg. We computed the orbit of each meteoroid and determined its Tisserand parameter. We found that meteoroids with asteroidal orbits have bulk densities ranging from 3000-5000 kgm-3. Meteoroids consistent with HTC/NIC parents have bulk densities from 400 kgm-3 to 1600 kg m-3. JFC meteoroids were found to have surprisingly

  5. Density in a Planetary Exosphere

    NASA Technical Reports Server (NTRS)

    Herring, Jackson; Kyle, Herbert L.

    1961-01-01

    A discussion of the Opik-Singer theory of the density of a planetary exosphere is presented. Their density formula permits the calculation of the depth of the exosphere. Since the correctness of their derivation of the basic formula for the density distribution has been questioned, an alternate method based directly on Liouville's theorem is given. It is concluded that the Opik-Singer formula seems valid for the ballistic component of the exosphere; but for a complete description of the planetary exosphere, the ionized and bound-orbit components must also be included.

  6. The effect of ligand substitution and water co-adsorption on the adsorption dynamics and energy level matching of amino-phenyl acid dyes on TiO2.

    PubMed

    Manzhos, Sergei; Segawa, Hiroshi; Yamashita, Koichi

    2012-02-01

    We perform a comparative theoretical analysis of adsorption of dyes NK1 (2E,4E-2-cyano-5-(4-dimethylaminophenyl)penta-2,4-dienoic acid) and NK7 (2E,4E-2-cyano-5-(4-diphenylaminophenyl)penta-2,4-dienoic acid) on clean and water-covered anatase (101) surfaces of TiO(2). Ligand substitution away from the anchoring group changes the energy level matching between the dye's LUMO and the oxide's conduction band. Monodentate binding and bidentate binding configurations of the dyes to TiO(2) are found to have similar adsorption energies even though the injection from the bidentate mode is found to dominate. Water has a strong effect on adsorption, inducing deprotonation and affecting strongly and differently between the dyes the energy level matching, leading to a shut-off of the injection from NK7 of bidentate adsorption configuration. Ab initio molecular dynamics simulations show a strong effect of nuclear motion on energy levels, specifically, increasing the driving force for injection in the monodentate regime. PMID:22194034

  7. FOREWORD: Special issue on density

    NASA Astrophysics Data System (ADS)

    Fujii, Kenichi

    2004-04-01

    This special issue on density was undertaken to provide readers with an overview of the present state of the density standards for solids, liquids and gases, as well as the technologies developed for measuring density. This issue also includes topics on the refractive index of gases and on techniques used for calibrating hydrometers so that almost all areas concerned with density standards are covered in four review articles and seven original articles, most of which describe current research being conducted at national metrology institutes (NMIs). A review article was invited from the Ruhr-Universität Bochum to highlight research on the magnetic suspension densimeters. In metrology, the determinations of the volume of a weight and the density of air are of primary importance in establishing a mass standard because the effect of the buoyancy force of air acting on the weight must be known accurately to determine the mass of the weight. A density standard has therefore been developed at many NMIs with a close relation to the mass standard. Hydrostatic weighing is widely used to measure the volume of a solid. The most conventional hydrostatic weighing method uses water as a primary density standard for measuring the volume of a solid. A brief history of the determination of the density of water is therefore given in a review article, as well as a recommended value for the density of water with a specified isotopic abundance. The most modern technique for hydrostatic weighing uses a solid density standard instead of water. For this purpose, optical interferometers for measuring the diameters of silicon spheres have been developed to convert the length standard into the volume standard with a small uncertainty. A review article is therefore dedicated to describing the state-of-the-art optical interferometers developed for silicon spheres. Relative combined standard uncertainties of several parts in 108 have been achieved today for measuring the volume and density of

  8. Measuring Ionization at Extreme Densities

    NASA Astrophysics Data System (ADS)

    Kraus, Dominik; Doeppner, Tilo; Kritcher, Andrea; Bachmann, Benjamin; Fletcher, Luke; Falcone, Roger; Gericke, Dirk; Glenzer, Siegfried; Masters, Nathan; Nora, Ryan; Boehm, Kurt; Divol, Laurent; Landen, Otto; Yi, Austin; Kline, John; Redmer, Ronald; Neumayer, Paul

    2015-11-01

    A precise knowledge of ionization at given temperature and density is crucial in order to properly model compressibility and heat capacity of ICF ablator materials for efficient implosions producing energy gain. Here, we present a new experimental platform to perform spectrally resolved x-ray scattering measurements of ionization, density and temperature in imploding CH or beryllium capsules on the National Ignition Facility. Recording scattered x-rays at 9 keV from a zinc He-alpha plasma source at a scattering angle of 120 degrees, first experiments show strong sensitivity to k-shell ionization, while at the same time constraining density and temperature. This platform will allow for x-ray Thomson scattering studies of dense plasmas with free electron densities up to 1025 cm-3, giving the possibility to investigate effects of continuum lowering and Pauli blocking on the ablator ionization state right before stagnation of the implosion.

  9. High density modular avionics packaging

    NASA Astrophysics Data System (ADS)

    Poradish, F.

    Requirements and design configurations for high density modular avionics packaging are examined, with particular attention given to new hardware trends, the design of high-density standard modules (HDSM's), and HDSM requirements. The discussion of the HDSM's covers thermal management, system testability, power supply, and performance specifications. The general design of an integrated HDSM demonstration system currently under construction is briefly described, and some test data are presented.

  10. Low density metal hydride foams

    DOEpatents

    Maienschein, Jon L.; Barry, Patrick E.

    1991-01-01

    Disclosed is a low density foam having a porosity of from 0 to 98% and a density less than about 0.67 gm/cc, prepared by heating a mixture of powered lithium hydride and beryllium hydride in an inert atmosphere at a temperature ranging from about 455 to about 490 K for a period of time sufficient to cause foaming of said mixture, and cooling the foam thus produced. Also disclosed is the process of making the foam.

  11. Trajectory versus probability density entropy.

    PubMed

    Bologna, M; Grigolini, P; Karagiorgis, M; Rosa, A

    2001-07-01

    We show that the widely accepted conviction that a connection can be established between the probability density entropy and the Kolmogorov-Sinai (KS) entropy is questionable. We adopt the definition of density entropy as a functional of a distribution density whose time evolution is determined by a transport equation, conceived as the only prescription to use for the calculation. Although the transport equation is built up for the purpose of affording a picture equivalent to that stemming from trajectory dynamics, no direct use of trajectory time evolution is allowed, once the transport equation is defined. With this definition in mind we prove that the detection of a time regime of increase of the density entropy with a rate identical to the KS entropy is possible only in a limited number of cases. The proposals made by some authors to establish a connection between the two entropies in general, violate our definition of density entropy and imply the concept of trajectory, which is foreign to that of density entropy. PMID:11461383

  12. Trajectory versus probability density entropy

    NASA Astrophysics Data System (ADS)

    Bologna, Mauro; Grigolini, Paolo; Karagiorgis, Markos; Rosa, Angelo

    2001-07-01

    We show that the widely accepted conviction that a connection can be established between the probability density entropy and the Kolmogorov-Sinai (KS) entropy is questionable. We adopt the definition of density entropy as a functional of a distribution density whose time evolution is determined by a transport equation, conceived as the only prescription to use for the calculation. Although the transport equation is built up for the purpose of affording a picture equivalent to that stemming from trajectory dynamics, no direct use of trajectory time evolution is allowed, once the transport equation is defined. With this definition in mind we prove that the detection of a time regime of increase of the density entropy with a rate identical to the KS entropy is possible only in a limited number of cases. The proposals made by some authors to establish a connection between the two entropies in general, violate our definition of density entropy and imply the concept of trajectory, which is foreign to that of density entropy.

  13. A summary of transition probabilities for atomic absorption lines formed in low-density clouds

    NASA Technical Reports Server (NTRS)

    Morton, D. C.; Smith, W. H.

    1973-01-01

    A table of wavelengths, statistical weights, and excitation energies is given for 944 atomic spectral lines in 221 multiplets whose lower energy levels lie below 0.275 eV. Oscillator strengths were adopted for 635 lines in 155 multiplets from the available experimental and theoretical determinations. Radiation damping constants also were derived for most of these lines. This table contains the lines most likely to be observed in absorption in interstellar clouds, circumstellar shells, and the clouds in the direction of quasars where neither the particle density nor the radiation density is high enough to populate the higher levels. All ions of all elements from hydrogen to zinc are included which have resonance lines longward of 912 A, although a number of weaker lines of neutrals and first ions have been omitted.

  14. Effects of Prepartum Dietary Energy Level and Nicotinic Acid Supplementation on Immunological, Hematological and Biochemical Parameters of Periparturient Dairy Cows Differing in Parity.

    PubMed

    Tienken, Reka; Kersten, Susanne; Frahm, Jana; Hüther, Liane; Meyer, Ulrich; Huber, Korinna; Rehage, Jürgen; Dänicke, Sven

    2015-01-01

    The periparturient period is critical according to health, productivity and profitability. As this period is fundamental for the success of the lactation period, the interest in improving periparturient health by dietary supplements increased in recent years. The present study investigated the effects of feeding nicotinic acid (NA) combined with varying dietary energy densities on immunological, hematological and biochemical parameters of periparturient cows differing in parity. Thirty-six multiparous and 20 primiparous dairy cows were enrolled in the study 42 days before expected parturition date until 100 days postpartum with the half of the cows being supplemented with 24 g of NA/d. After parturition a diet with 30% concentrate was fed to all cows which was followed by different concentrate escalation strategies. Dietary NA supplementation was ceased on day 24 postpartum. Dietary NA increased (P = 0.010) serum nicotinamide concentrations (mean of 3.35 ± 1.65 µg/mL), whereas NA could not be detected. Present data emphasize that periparturient cows are faced with major physiological challenges and that both parity-groups have different prerequisites to adapt to those changes irrespective of NA supplementation. The overfeeding of energy to cows which were similar in body condition score had only minor effects on periparturient immune system function and the metabolism of those cows. PMID:26479393

  15. Density Distributions of Cyclotrimethylenetrinitramines (RDX)

    SciTech Connect

    Hoffman, D M

    2002-03-19

    As part of the US Army Foreign Comparative Testing (FCT) program the density distributions of six samples of class 1 RDX were measured using the density gradient technique. This technique was used in an attempt to distinguish between RDX crystallized by a French manufacturer (designated insensitive or IRDX) from RDX manufactured at Holston Army Ammunition Plant (HAAP), the current source of RDX for Department of Defense (DoD). Two samples from different lots of French IRDX had an average density of 1.7958 {+-} 0.0008 g/cc. The theoretical density of a perfect RDX crystal is 1.806 g/cc. This yields 99.43% of the theoretical maximum density (TMD). For two HAAP RDX lots the average density was 1.786 {+-} 0.002 g/cc, only 98.89% TMD. Several other techniques were used for preliminary characterization of one lot of French IRDX and two lot of HAAP RDX. Light scattering, SEM and polarized optical microscopy (POM) showed that SNPE and Holston RDX had the appropriate particle size distribution for Class 1 RDX. High performance liquid chromatography showed quantities of HMX in HAAP RDX. French IRDX also showed a 1.1 C higher melting point compared to HAAP RDX in the differential scanning calorimetry (DSC) consistent with no melting point depression due to the HMX contaminant. A second part of the program involved characterization of Holston RDX recrystallized using the French process. After reprocessing the average density of the Holston RDX was increased to 1.7907 g/cc. Apparently HMX in RDX can act as a nucleating agent in the French RDX recrystallization process. The French IRDX contained no HMX, which is assumed to account for its higher density and narrower density distribution. Reprocessing of RDX from Holston improved the average density compared to the original Holston RDX, but the resulting HIRDX was not as dense as the original French IRDX. Recrystallized Holston IRDX crystals were much larger (3-500 {micro}m or more) then either the original class 1 HAAP RDX or

  16. Imaginary time density-density correlations for two-dimensional electron gases at high density

    SciTech Connect

    Motta, M.; Galli, D. E.; Moroni, S.; Vitali, E.

    2015-10-28

    We evaluate imaginary time density-density correlation functions for two-dimensional homogeneous electron gases of up to 42 particles in the continuum using the phaseless auxiliary field quantum Monte Carlo method. We use periodic boundary conditions and up to 300 plane waves as basis set elements. We show that such methodology, once equipped with suitable numerical stabilization techniques necessary to deal with exponentials, products, and inversions of large matrices, gives access to the calculation of imaginary time correlation functions for medium-sized systems. We discuss the numerical stabilization techniques and the computational complexity of the methodology and we present the limitations related to the size of the systems on a quantitative basis. We perform the inverse Laplace transform of the obtained density-density correlation functions, assessing the ability of the phaseless auxiliary field quantum Monte Carlo method to evaluate dynamical properties of medium-sized homogeneous fermion systems.

  17. Seasonal variations in energy levels and metabolic processes of two dominant Acropora species ( A. spicifera and A. digitifera) at Ningaloo Reef

    NASA Astrophysics Data System (ADS)

    Hinrichs, S.; Patten, N. L.; Allcock, R. J. N.; Saunders, S. M.; Strickland, D.; Waite, A. M.

    2013-09-01

    Seasonal variations in coral health indices reflecting autotrophic activity (chlorophyll a and zooxanthellae density), metabolic rates (RNA/DNA ratio and protein) and energy storage (ratio of storage: structural lipids or lipid ratios) were examined for two dominant Acropora species [ Acropora digitifera ( AD) and Acropora spicifera ( AS)] at Ningaloo Reef (north-western Australia). Such detailed investigation of metabolic processes is important background, with regard to understanding the vulnerability of corals to environmental change. Health indices in AD and AS were measured before and after spawning in austral autumn and winter 2010, and austral summer 2011 at six stations. Health indices showed seasonal and species-specific differences but negligible spatial differences across a reef section. For AD, autotrophic indices were negatively correlated with lipid ratios and metabolic indices. Metabolic indices were significantly higher in AS than AD. No correlation was observed between RNA/DNA ratios and lipid ratios with any autotrophic indices for AS. Lipid ratios were stable throughout the year for AS while they changed significantly for AD. For both species, indices of metabolic activity were highest during autumn, while autotrophic indices were highest in winter and summer. Results suggest that the impact of the broadcast spawning event on coral health indices at Ningaloo Reef occurred only as a backdrop to massive seasonal changes in coral physiology. The La Niña summer pattern resulted in high autotrophic indices and low metabolic indices and energy stores. Our results imply different metabolic processes in A. digitifera and A. spicifera as well as a strong impact of extreme events on coral physiology.

  18. Effects of Prepartum Dietary Energy Level and Nicotinic Acid Supplementation on Immunological, Hematological and Biochemical Parameters of Periparturient Dairy Cows Differing in Parity

    PubMed Central

    Tienken, Reka; Kersten, Susanne; Frahm, Jana; Hüther, Liane; Meyer, Ulrich; Huber, Korinna; Rehage, Jürgen; Dänicke, Sven

    2015-01-01

    Simple Summary Several biological changes occur during the transition from late pregnancy to early lactation which is associated with a high susceptibility of health disorders. Nicotinic acid, as feed additive, is suggested to balance catabolic metabolism of periparturient dairy cows by attenuating lipolysis and impact production performance. This study provides information of the biological changes occurring around parturition with special emphasis on differences between primiparous and multiparous cows. Present results showed that energy-dense feeding prepartum did not result in metabolic imbalances postpartum in dairy cows which were similar in body condition score. Nicotinic acid supplementation did not reveal any effect. Abstract The periparturient period is critical according to health, productivity and profitability. As this period is fundamental for the success of the lactation period, the interest in improving periparturient health by dietary supplements increased in recent years. The present study investigated the effects of feeding nicotinic acid (NA) combined with varying dietary energy densities on immunological, hematological and biochemical parameters of periparturient cows differing in parity. Thirty-six multiparous and 20 primiparous dairy cows were enrolled in the study 42 days before expected parturition date until 100 days postpartum with the half of the cows being supplemented with 24 g of NA/d. After parturition a diet with 30% concentrate was fed to all cows which was followed by different concentrate escalation strategies. Dietary NA supplementation was ceased on day 24 postpartum. Dietary NA increased (P = 0.010) serum nicotinamide concentrations (mean of 3.35 ± 1.65 µg/mL), whereas NA could not be detected. Present data emphasize that periparturient cows are faced with major physiological challenges and that both parity-groups have different prerequisites to adapt to those changes irrespective of NA supplementation. The overfeeding of

  19. Liquid Densities of Fluorinated Ethers

    NASA Astrophysics Data System (ADS)

    Nakazawa, Noriaki; Sako, Takeshi; Nakane, Takashi; Sekiya, Akira; Kawamura, Mitsutaka; Sato, Masahito; Mochizuki, Yuji; Takada, Naoto; Yasumoto, Masahiko

    The liquid densities of thirteen fluorinated ethers which are expected as promising candidates of CFC alternatives were measured at temperatures from 278 K to 323 K and atmospheric pressure. The fluorinated ethers used in this study are 1-difluoromethoxy-1,1, 2- trifluoroethane, 1-methoxy-1, 1,2,2-tetrafluoroethane, 1-methoxy-2,2 ,3 ,3- tetrafluoropropane, 1-methoxy-1-trifluoromethy1-2,2 ,2- trifluoroethane, 1-methoxy-1,1,2,2, 3-hexafluoropropane,1-difluoromethoxy-2,2, 3, 3 -tetrafluoropropane, 1-methoxy-heptafluoropropane,1-difluoromethoxy-2, 2, 3, 3, 3-pentafluoropropane, 1- (2, 2, 2-trifruoroethoxy) -1, 1, 2,2-tetrafluoroethane, 1-pentafluoroethoxy-1, 1, 2, 2-tetrafluoroethane,2-trifluoromethoxy-1, 1, 1,2-tetrafluorobutane, 1-proxynonafluorobutane, and 1-ethoxy-undecafluoropentane. The liquid density has been measured by the vibrating tube densitometer (ANTON PARR, DMA 602) within an error of 0.07%. The liquid densities decrease monotonically with increase of temperature.

  20. Proposed reactor coolant density monitor

    SciTech Connect

    Mackley, A.D.

    1986-01-01

    Until now there has been no feasible method of monitoring coolant density in the environment of an operating reactor core. By analysis of output from self-powered neutron detectors (SPNDs) in the core of the Loss of Fluid Test (LOFT) Reactor, the author has successfully estimated local coolant densities under post-scram conditions during a large break loss of coolant transient. The model used for estimation is not fully explained by published principles on the interaction of gamma rays with SPNDs. However, based on the success of the model, the author proposes employing self powered gamma detectors (SPGDs) to monitor reactor coolant density and discusses areas of experimental work to establish the best conditions for this application. 9 refs., 12 figs.

  1. Union Density and Hospital Outcomes.

    PubMed

    Koys, Daniel J; Martin, Wm Marty; LaVan, Helen; Katz, Marsha

    2015-01-01

    The authors address the hospital outcomes of patient satisfaction, healthcare quality, and net income per bed. They define union density as the percentage of a hospital's employees who are in unions, healthcare quality as its 30-day acute myocardial infraction (AMI; heart attack) mortality rate, and patient satisfaction as its overall Hospital Consumer Assessment of Healthcare Providers and Systems score. Using a random sample of 84 union and 84 nonunion hospitals from across the United States, multiple regression analyses show that union density is negatively related to patient satisfaction. Union density is not related to healthcare quality as measured by the AMI mortality rate or to net income per bed. This implies that unions per se are not good or bad for hospitals. The authors suggest that it is better for hospital administrators to take a Balanced Scorecard approach and be concerned about employee satisfaction, patient satisfaction, healthcare quality, and net income. PMID:26652043

  2. High Energy Density Electrolytic Capacitor

    NASA Technical Reports Server (NTRS)

    Evans, David A.

    1996-01-01

    A new type of electrolytic capacitor which combines an electrolytic capacitor anode with an electrochemical capacitor cathode was developed. The resulting capacitor has a four time higher energy density than standard electrolytic capacitors, with comparable electric performance. The prototype, a 480 microFarad, 200 V device, has an energy density exceeding 4 J/cc. Now a 680 microFarad 50 V, MIL-style all tantalum device has been constructed and is undergoing qualification testing. Pending a favorable outcome, work will begin on other ratings. The potential for commercially significant development exists in applying this technology to aluminum-based electrolytic capacitors. It is possible to at least double the energy density of aluminum electrolytics, while using existing manufacturing methods, and without adding material expense. Data presented include electrical characteristics and performance measurements of the 200 V and 50 V hybrid capacitors and results from ongoing qualification testing of the MIL-style tantalum capacitors.

  3. High energy density electrolytic capacitor

    NASA Technical Reports Server (NTRS)

    Evans, David A.

    1995-01-01

    Recently a new type of electrolytic capacitor was developed. This capacitor, the Evans Hybrid, combines an electrolytic capacitor anode with an electrochemical capacitors cathode. The resulting capacitor has four times the energy density of other electrolytic capacitors, with comparable electrical performance. The prototype, a 480 micro F, 200 V device, had an energy density exceeding 4 J/cc. Now, a 680 micro F, 50 V, MIL-style all tantalum device has been constructed and is undergoing qualification testing. Pending a favorable outcome, work will begin on other ratings. Potential for commercially significant development exists in applying this technology to aluminum-based electrolytic capacitors. It is possible to at least double the energy density of aluminum electrolytics, while using existing manufacturing methods, and without adding material expense. Data presented include electrical characteristics and performance measurements of the 200 V and 50 V Hybrid capacitors and results of ongolng qualification status of the MJL-style tantalum.

  4. Calibrating transition-metal energy levels and oxygen bands in first-principles calculations: Accurate prediction of redox potentials and charge transfer in lithium transition-metal oxides

    NASA Astrophysics Data System (ADS)

    Seo, Dong-Hwa; Urban, Alexander; Ceder, Gerbrand

    2015-09-01

    Transition-metal (TM) oxides play an increasingly important role in technology today, including applications such as catalysis, solar energy harvesting, and energy storage. In many of these applications, the details of their electronic structure near the Fermi level are critically important for their properties. We propose a first-principles-based computational methodology for the accurate prediction of oxygen charge transfer in TM oxides and lithium TM (Li-TM) oxides. To obtain accurate electronic structures, the Heyd-Scuseria-Ernzerhof (HSE06) hybrid functional is adopted, and the amount of exact Hartree-Fock exchange (mixing parameter) is adjusted to reproduce reference band gaps. We show that the HSE06 functional with optimal mixing parameter yields not only improved electronic densities of states, but also better energetics (Li-intercalation voltages) for LiCo O2 and LiNi O2 as compared to the generalized gradient approximation (GGA), Hubbard U corrected GGA (GGA +U ), and standard HSE06. We find that the optimal mixing parameters for TM oxides are system specific and correlate with the covalency (ionicity) of the TM species. The strong covalent (ionic) nature of TM-O bonding leads to lower (higher) optimal mixing parameters. We find that optimized HSE06 functionals predict stronger hybridization of the Co 3 d and O 2 p orbitals as compared to GGA, resulting in a greater contribution from oxygen states to charge compensation upon delithiation in LiCo O2 . We also find that the band gaps of Li-TM oxides increase linearly with the mixing parameter, enabling the straightforward determination of optimal mixing parameters based on GGA (α =0.0 ) and HSE06 (α =0.25 ) calculations. Our results also show that G0W0@GGA +U band gaps of TM oxides (M O ,M =Mn ,Co ,Ni ) and LiCo O2 agree well with experimental references, suggesting that G0W0 calculations can be used as a reference for the calibration of the mixing parameter in cases when no experimental band gap has been

  5. Semiclassical origins of density functionals

    NASA Astrophysics Data System (ADS)

    Burke, Kieron

    By careful numerical analysis of non-relativistic atomic correlation energies, we show that (a) the local density approximation becomes relatively exact for the correlation energy as the atomic number approaches infinity, (b) we find the leading correction, which is about 38.5 milliHartrees per atom, (c) show how this correction dominates for larger atoms and (d) how to construct a generalized gradient approximation that respects this limit (See KB, A. Cancio, T. Gould, S. Pittalis, arXiv:1409.4834). The relevance to density functional calculations will also be explained. Support provided by NSF CHE-1464795.

  6. Photoionization and High Density Gas

    NASA Technical Reports Server (NTRS)

    Kallman, T.; Bautista, M.; White, Nicholas E. (Technical Monitor)

    2002-01-01

    We present results of calculations using the XSTAR version 2 computer code. This code is loosely based on the XSTAR v.1 code which has been available for public use for some time. However it represents an improvement and update in several major respects, including atomic data, code structure, user interface, and improved physical description of ionization/excitation. In particular, it now is applicable to high density situations in which significant excited atomic level populations are likely to occur. We describe the computational techniques and assumptions, and present sample runs with particular emphasis on high density situations.

  7. Direct comparative study on the energy level alignments in unoccupied/occupied states of organic semiconductor/electrode interface by constructing in-situ photoemission spectroscopy and Ar gas cluster ion beam sputtering integrated analysis system

    SciTech Connect

    Yun, Dong-Jin Chung, JaeGwan; Kim, Yongsu; Park, Sung-Hoon; Kim, Seong-Heon; Heo, Sung

    2014-10-21

    Through the installation of electron gun and photon detector, an in-situ photoemission and damage-free sputtering integrated analysis system is completely constructed. Therefore, this system enables to accurately characterize the energy level alignments including unoccupied/occupied molecular orbital (LUMO/HOMO) levels at interface region of organic semiconductor/electrode according to depth position. Based on Ultraviolet Photoemission Spectroscopy (UPS), Inverse Photoemission Spectroscopy (IPES), and reflective electron energy loss spectroscopy, the occupied/unoccupied state of in-situ deposited Tris[4-(carbazol-9-yl)phenyl]amine (TCTA) organic semiconductors on Au (E{sub LUMO}: 2.51 eV and E{sub HOMO}: 1.35 eV) and Ti (E{sub LUMO}: 2.19 eV and E{sub HOMO}: 1.69 eV) electrodes are investigated, and the variation of energy level alignments according to work function of electrode (Au: 4.81 eV and Ti: 4.19 eV) is clearly verified. Subsequently, under the same analysis condition, the unoccupied/occupied states at bulk region of TCTA/Au structures are characterized using different Ar gas cluster ion beam (Ar GCIB) and Ar ion sputtering processes, respectively. While the Ar ion sputtering process critically distorts both occupied and unoccupied states in UPS/IPES spectra, the Ar GCIB sputtering process does not give rise to damage on them. Therefore, we clearly confirm that the in-situ photoemission spectroscopy in combination with Ar GCIB sputtering allows of investigating accurate energy level alignments at bulk/interface region as well as surface region of organic semiconductor/electrode structure.

  8. Information Density and Syntactic Repetition

    ERIC Educational Resources Information Center

    Temperley, David; Gildea, Daniel

    2015-01-01

    In noun phrase (NP) coordinate constructions (e.g., NP and NP), there is a strong tendency for the syntactic structure of the second conjunct to match that of the first; the second conjunct in such constructions is therefore low in syntactic information. The theory of uniform information density predicts that low-information syntactic…

  9. The Classroom: Size versus Density.

    ERIC Educational Resources Information Center

    Tanner, C. Kenneth

    2000-01-01

    Classroom density may be a more important planning consideration than size. The lower middle range for human social distance is 7 feet--not met in most classrooms containing 20 to 25 students. Students need ample space, since crowding causes behavior problems and increased maintenance costs. (Contains 10 references.) (MLH)

  10. Densities of aqueous blended amines

    SciTech Connect

    Hsu, C.H.; Li, M.H.

    1997-05-01

    Solutions of alkanolamines are an industrially important class of compounds used in the natural gas and synthetic ammonia industries and petroleum chemical plants for the removal of CO{sub 2} and H{sub 2}S from gas streams. The densities of aqueous mixtures of diethanolamine (DEA) + N-methyldiethanolamine (MDEA) + water, DEA + 2-amino-2-methyl-1-propanol (AMP) + water, and monoethanolamine (MEA) + 2-piperidineethanol (2-PE) + water were measured from 30 C to 80 C. A Redlich-Kister equation of the excess volume was applied to represent the density. Based on the available density data for five ternary systems: MEA + MDEA + H{sub 2}O, MEA + AMP + H{sub 2}O, DEA + MDEA + H{sub 2}O, DEA + AMP + H{sub 2}O, and MEA + 2-PE + H{sub 2}O, a generalized set of binary parameters were determined. The density calculations show quite satisfactory results. The overall average absolute percent deviation is about 0.04% for a total of 686 data points.

  11. Density Functionals of Chemical Bonding

    PubMed Central

    Putz, Mihai V.

    2008-01-01

    The behavior of electrons in general many-electronic systems throughout the density functionals of energy is reviewed. The basic physico-chemical concepts of density functional theory are employed to highlight the energy role in chemical structure while its extended influence in electronic localization function helps in chemical bonding understanding. In this context the energy functionals accompanied by electronic localization functions may provide a comprehensive description of the global-local levels electronic structures in general and of chemical bonds in special. Becke-Edgecombe and author’s Markovian electronic localization functions are discussed at atomic, molecular and solid state levels. Then, the analytical survey of the main workable kinetic, exchange, and correlation density functionals within local and gradient density approximations is undertaken. The hierarchy of various energy functionals is formulated by employing both the parabolic and statistical correlation degree of them with the electronegativity and chemical hardness indices by means of quantitative structure-property relationship (QSPR) analysis for basic atomic and molecular systems. PMID:19325846

  12. Plasma digital density determining device

    DOEpatents

    Sprott, Julien C.; Lovell, Thomas W.; Holly, Donald J.

    1976-01-01

    The density of a decaying plasma in an electrically conducting enclosure is determined by applying an excitation to the cavity formed by the enclosure and counting digitally the number of resonant frequencies traversed by the combination of the cavity and the decaying plasma.

  13. The Maximum Density of Water.

    ERIC Educational Resources Information Center

    Greenslade, Thomas B., Jr.

    1985-01-01

    Discusses a series of experiments performed by Thomas Hope in 1805 which show the temperature at which water has its maximum density. Early data cast into a modern form as well as guidelines and recent data collected from the author provide background for duplicating Hope's experiments in the classroom. (JN)

  14. Maximum-likelihood density modification

    PubMed Central

    Terwilliger, Thomas C.

    2000-01-01

    A likelihood-based approach to density modification is developed that can be applied to a wide variety of cases where some information about the electron density at various points in the unit cell is available. The key to the approach consists of developing likelihood functions that represent the probability that a particular value of electron density is consistent with prior expectations for the electron density at that point in the unit cell. These likelihood functions are then combined with likelihood functions based on experimental observations and with others containing any prior knowledge about structure factors to form a combined likelihood function for each structure factor. A simple and general approach to maximizing the combined likelihood function is developed. It is found that this likelihood-based approach yields greater phase improvement in model and real test cases than either conventional solvent flattening and histogram matching or a recent reciprocal-space solvent-flattening procedure [Terwilliger (1999 ▶), Acta Cryst. D55, 1863–1871]. PMID:10944333

  15. Dual Cryogenic Capacitive Density Sensor

    NASA Technical Reports Server (NTRS)

    Youngquist, Robert; Mata, Carlos; Vokrot, Peter; Cox, Robert

    2009-01-01

    A dual cryogenic capacitive density sensor has been developed. The device contains capacitive sensors that monitor two-phase cryogenic flow density to within 1% accuracy, which, if temperature were known, could be used to determine the ratio of liquid to gas in the line. Two of these density sensors, located a known distance apart, comprise the sensor, providing some information on the velocity of the flow. This sensor was constructed as a proposed mass flowmeter with high data acquisition rates. Without moving parts, this device is capable of detecting the density change within a two-phase cryogenic flow more than 100 times a second. Detection is enabled by a series of two sets of five parallel plates with stainless steel, cryogenically rated tubing. The parallel plates form the two capacitive sensors, which are measured by electrically isolated digital electronics. These capacitors monitor the dielectric of the flow essentially the density of the flow and can be used to determine (along with temperature) the ratio of cryogenic liquid to gas. Combining this information with the velocity of the flow can, with care, be used to approximate the total two-phase mass flow. The sensor can be operated at moderately high pressures and can be lowered into a cryogenic bath. The electronics have been substantially improved over the older sensors, incorporating a better microprocessor, elaborate ground loop protection and noise limiting circuitry, and reduced temperature sensitivity. At the time of this writing, this design has been bench tested at room temperature, but actual cryogenic tests are pending

  16. Estimation of coastal density gradients

    NASA Astrophysics Data System (ADS)

    Howarth, M. J.; Palmer, M. R.; Polton, J. A.; O'Neill, C. K.

    2012-04-01

    Density gradients in coastal regions with significant freshwater input are large and variable and are a major control of nearshore circulation. However their measurement is difficult, especially where the gradients are largest close to the coast, with significant uncertainties because of a variety of factors - spatial and time scales are small, tidal currents are strong and water depths shallow. Whilst temperature measurements are relatively straightforward, measurements of salinity (the dominant control of spatial variability) can be less reliable in turbid coastal waters. Liverpool Bay has strong tidal mixing and receives fresh water principally from the Dee, Mersey, Ribble and Conwy estuaries, each with different catchment influences. Horizontal and vertical density gradients are variable both in space and time. The water column stratifies intermittently. A Coastal Observatory has been operational since 2002 with regular (quasi monthly) CTD surveys on a 9 km grid, an situ station, an instrumented ferry travelling between Birkenhead and Dublin and a shore-based HF radar system measuring surface currents and waves. These measurements are complementary, each having different space-time characteristics. For coastal gradients the ferry is particularly useful since measurements are made right from the mouth of Mersey. From measurements at the in situ site alone density gradients can only be estimated from the tidal excursion. A suite of coupled physical, wave and ecological models are run in association with these measurements. The models, here on a 1.8 km grid, enable detailed estimation of nearshore density gradients, provided appropriate river run-off data are available. Examples are presented of the density gradients estimated from the different measurements and models, together with accuracies and uncertainties, showing that systematic time series measurements within a few kilometres of the coast are a high priority. (Here gliders are an exciting prospect for

  17. Spatial Symmetries of the Local Densities

    SciTech Connect

    Rohozinski, S.; Dobaczewski, J.; Nazarewicz, Witold

    2010-01-01

    Spatial symmetries of the densities appearing in the nuclear Density Functional Theory are discussed. General forms of the local densities are derived by using methods of construction of isotropic tensor fields. The spherical and axial cases are considered.

  18. Statistical density modification using local pattern matching

    DOEpatents

    Terwilliger, Thomas C.

    2007-01-23

    A computer implemented method modifies an experimental electron density map. A set of selected known experimental and model electron density maps is provided and standard templates of electron density are created from the selected experimental and model electron density maps by clustering and averaging values of electron density in a spherical region about each point in a grid that defines each selected known experimental and model electron density maps. Histograms are also created from the selected experimental and model electron density maps that relate the value of electron density at the center of each of the spherical regions to a correlation coefficient of a density surrounding each corresponding grid point in each one of the standard templates. The standard templates and the histograms are applied to grid points on the experimental electron density map to form new estimates of electron density at each grid point in the experimental electron density map.

  19. Understanding density functional theory (DFT) and completing it in practice

    SciTech Connect

    Bagayoko, Diola

    2014-12-15

    We review some salient points in the derivation of density functional theory (DFT) and of the local density approximation (LDA) of it. We then articulate an understanding of DFT and LDA that seems to be ignored in the literature. We note the well-established failures of many DFT and LDA calculations to reproduce the measured energy gaps of finite systems and band gaps of semiconductors and insulators. We then illustrate significant differences between the results from self consistent calculations using single trial basis sets and those from computations following the Bagayoko, Zhao, and Williams (BZW) method, as enhanced by Ekuma and Franklin (BZW-EF). Unlike the former, the latter calculations verifiably attain the absolute minima of the occupied energies, as required by DFT. These minima are one of the reasons for the agreement between their results and corresponding, experimental ones for the band gap and a host of other properties. Further, we note predictions of DFT BZW-EF calculations that have been confirmed by experiment. Our subsequent description of the BZW-EF method ends with the application of the Rayleigh theorem in the selection, among the several calculations the method requires, of the one whose results have a full, physics content ascribed to DFT. This application of the Rayleigh theorem adds to or completes DFT, in practice, to preserve the physical content of unoccupied, low energy levels. Discussions, including implications of the method, and a short conclusion follow the description of the method. The successive augmentation of the basis set in the BZW-EF method, needed for the application of the Rayleigh theorem, is also necessary in the search for the absolute minima of the occupied energies, in practice.

  20. The excited state dynamics of KLa(MoO{sub 4}){sub 2}:Pr{sup 3+}: From a case study to the determination of the energy levels of rare earth impurities relative to the bandgap in oxidising host lattices

    SciTech Connect

    Cavalli, Enrico Boutinaud, Philippe; Bettinelli, Marco; Dorenbos, Pieter

    2008-05-15

    The luminescence properties of KLa(MoO{sub 4}){sub 2} (KLM) single crystals doped with Pr{sup 3+} have been measured in the 10-600 K temperature range in order to investigate the mechanisms involved in the radiationless processes. At variance with previously studied scheelite-like molybdates activated with Pr{sup 3+}, no effects attributed to the formation of intervalence charge transfer states have been observed. The model proposed in order to account for this behaviour allows the determination of the energy of the Pr{sup 3+} levels relative to the valence and conduction bands of the host. This model has firstly been confirmed for Tb{sup 3+}-doped KLM, for which suitable experimental data are available, and then extended to the other rare earth ions on the basis of the systematic nature of the lanthanide energy levels properties. The obtained conclusions are finally supported in the light of the comparison with some other representative cases. - Graphical abstract: The study of the excited state dynamics of KLa(MoO{sub 4}){sub 2} single crystals doped with Pr{sup 3+} allows to determine the energies of the levels of the active ion relative to the valence and conduction bands of the host. This model has then been extended to the other rare earth ions on the basis of the systematic nature of the lanthanide energy levels properties.

  1. Density limit disruptions in tokamaks

    NASA Astrophysics Data System (ADS)

    Kleva, Robert G.; Drake, J. F.

    1991-02-01

    Magnetohydrodynamic simulations are presented which reproduce the rapid drop in the central temperature observed during density limit disruptions in tokamaks. The loss of central confinement is triggered by edge radiation which destabilizes a q=1 kink mode. A bubble of cold plasma is injected from the edge into the center by the q=1 kink. This bubble bears a striking resemblance to the cold plasma that is observed to move from the edge into the center during density limit disruptions on the JET tokamak [Plasma Physics and Controlled Nuclear Fusion Research 1986 (IAEA, Vienna, 1987), Vol. 1, p. 433], initiating the loss of central confinement. The bubble profile produced by the q=1 kink is unstable to a broad spectrum of modes which progressively reduce the magnetic shear between the q=2 surface and the center. The q=2 mode then grows across the center, broadening the current and throwing the hot plasma to the wall.

  2. Probability densities in strong turbulence

    NASA Astrophysics Data System (ADS)

    Yakhot, Victor

    2006-03-01

    In this work we, using Mellin’s transform combined with the Gaussian large-scale boundary condition, calculate probability densities (PDFs) of velocity increments P(δu,r), velocity derivatives P(u,r) and the PDF of the fluctuating dissipation scales Q(η,Re), where Re is the large-scale Reynolds number. The resulting expressions strongly deviate from the Log-normal PDF P(δu,r) often quoted in the literature. It is shown that the probability density of the small-scale velocity fluctuations includes information about the large (integral) scale dynamics which is responsible for the deviation of P(δu,r) from P(δu,r). An expression for the function D(h) of the multifractal theory, free from spurious logarithms recently discussed in [U. Frisch, M. Martins Afonso, A. Mazzino, V. Yakhot, J. Fluid Mech. 542 (2005) 97] is also obtained.

  3. Generalized Expression for Polarization Density

    SciTech Connect

    Lu Wang and T.S. Hahm

    2009-04-23

    A general polarization density which consists of classical and neoclassical parts is system-atically derived via modern gyrokinetics and bounce-kinetics by employing a phase-space Lagrangian Lie-transform perturbation method. The origins of polarization density are further elucidated. Extending the work on neoclassical polarization for long wavelength compared to ion banana width [M. N. Rosenbluth and F. L. Hinton, Phys. Rev. Lett. 80, 724 (1998)], an analytical formula for the generalized neoclassical polarization including both finite-banana-width (FBW) and finite-Larmor-radius (FLR) effects for arbitrary radial wavelength in comparison to banana width and gyroradius is derived. In additional to the contribution from trapped particles, the contribution of passing particles to the neoclassical polarization is also explicitly calculated. Our analytic expression agrees very well with the previous numerical results for a wide range of radial wavelength.

  4. Generalized expression for polarization density

    SciTech Connect

    Wang Lu; Hahm, T. S.

    2009-06-15

    A general polarization density which consists of classical and neoclassical parts is systematically derived via modern gyrokinetics and bounce kinetics by employing a phase-space Lagrangian Lie-transform perturbation method. The origins of polarization density are further elucidated. Extending the work on neoclassical polarization for long wavelength compared to ion banana width [M. N. Rosenbluth and F. L. Hinton, Phys. Rev. Lett. 80, 724 (1998)], an analytical formula for the generalized neoclassical polarization including both finite-banana-width and finite-Larmor-radius effects for arbitrary radial wavelength in comparison to banana width and gyroradius is derived. In additional to the contribution from trapped particles, the contribution of passing particles to the neoclassical polarization is also explicitly calculated. The generalized analytic expression agrees very well with the previous numerical results for a wide range of radial wavelength.

  5. Stable density stratification solar pond

    NASA Technical Reports Server (NTRS)

    Lansing, F. L. (Inventor)

    1985-01-01

    A stable density-stratification solar pond for use in the collection and storage of solar thermal energy including a container having a first section characterized by an internal wall of a substantially cylindrical configuration and a second section having an internal wall of a substantially truncated conical configuration surmounting the first section in coaxial alignment therewith, the second section of said container being characterized by a base of a diameter substantially equal to the diameter of the first section and a truncated apex defining a solar energy acceptance opening is discussed. A body of immiscible liquids is disposed within the container and comprises a lower portion substantially filling the first section of the container and an upper portion substantially filling the second section of the container, said lower portion being an aqueous based liquid of a darker color than the upper portion and of a greater density. A protective cover plate is removably provided for covering the acceptance opening.

  6. High Energy Density Laboratory Astrophysics

    SciTech Connect

    Remington, B A

    2004-11-11

    High-energy-density (HED) physics refers broadly to the study of macroscopic collections of matter under extreme conditions of temperature and density. The experimental facilities most widely used for these studies are high-power lasers and magnetic-pinch generators. The HED physics pursued on these facilities is still in its infancy, yet new regimes of experimental science are emerging. Examples from astrophysics include work relevant to planetary interiors, supernovae, astrophysical jets, and accreting compact objects (such as neutron stars and black holes). In this paper, we will review a selection of recent results in this new field of HED laboratory astrophysics and provide a brief look ahead to the coming decade.

  7. Mineral deposit density; an update

    USGS Publications Warehouse

    Singer, Donald A.; Menzie, W. David; Sutphin, David M.; Mosier, Dan L.; Bliss, James D.; contributions to global mineral resource assessment research edited by Schulz, Klaus J.

    2001-01-01

    A robust method to estimate the number of undiscovered deposits is a form of mineral deposit model wherein numbers of deposits per unit area from well-explored regions are counted and the resulting frequency distribution is used either directly for an estimate or indirectly as a guideline in some other method. The 27 mineral deposit density estimates reported here for 13 different deposit types represent a start at compiling the estimates necessary to guide assessments.

  8. Acoustic measurements of gas density

    NASA Technical Reports Server (NTRS)

    Shakkottai, P.; Kwack, E. Y.; Back, L. H.

    1990-01-01

    Sound transmission through gases in an enclosure is considered. Analytical results are given in terms of geometrical parameters, wave numbers, and source type for simple model problems, and are compared with data obtained by Haran (1983). It is concluded that density measurements can be made in a gas contained in an enclosure by measuring the sound pressure level at a receiver located near a dipole source driven at a constant velocity amplitude at low frequencies.

  9. Neutron densities from muon capture

    NASA Astrophysics Data System (ADS)

    Huan Ching, Chiang; Oset, Eulogio

    1991-10-01

    We show that, because of Pauli blocking and renormalization of the weak currents in nuclei, the muon capture rates are rather sensitive to the neutron distributions. We also show that, because of intrinsic theoretical uncertainties, neutron radia cannot be determined with precision but some reasonable limits can be given. However, the ratio of capture rates in different isotopes serves to determine the neutron radii of the isotopes provided the neutron density distribution for one of them is known.

  10. Improved energy density homopolar generator

    NASA Astrophysics Data System (ADS)

    Walls, W. A.; Weldon, Wm. F.; Driga, M. D.; Manifold, S. M.; Woodson, H. H.

    1986-11-01

    The preliminary design of a self excited, air-core (SEAC) homopolar generator (HPG) which stores about 250 MJ inertially and is capable of delivering 3.2 MA current pulses is presented. In aiming for maximum energy density in an HPG and inductor power supply for electromagnetic (EM) accelerators, the improved energy density (IED) machine uses its self-excited field coils as energy storage inductors and a lightweight graphite reinforced flywheel for inertial energy storage. Weighing approximately 5,000 kg, the design represents a twenty-fold increase in mass energy density over the state of the art and addresses the problem of trapping flux in the rotor during discharge by separating the voltage generating and energy storage functions. Voltage is generated across a squirrel-cage rotor armature by an opposed pair of five-turn cryogenically cooled field coils/inductors. Inertial energy is stored in a graphite-reinforced epoxy flywheel which will operate at a maximum tip speed of 1,100 m/s. The machine is expected to develop about 500 V at half speed while charging the coils to 130 MJ at 3.2 MA. Peak output voltage during discharge of coils will be roughly 10 kV.

  11. Low-density ionization behavior

    SciTech Connect

    Baker, G.A. Jr.

    1995-04-01

    As part of a continuing study of the physics of matter under extreme conditions, I give some results on matter at extremely low density. In particular I compare a quantum mechanical calculation of the pressure for atomic hydrogen with the corresponding pressure given by Thomas-Fermi theory. (This calculation differs from the ``confined atom`` approximation in a physically significant way.) Since Thomas-Fermi theory in some sense, represents the case of infinite nuclear charge, these cases should represent extremes. Comparison is also made with Saha theory, which considers ionization from a chemical point of view, but is weak on excited-state effects. In this theory, the pressure undergoes rapid variation as electron ionization levels are passed. This effect is in contrast to the smooth behavior of the Thomas-Fermi fixed temperature, complete ionization occurs in the low density limit, I study the case where the temperature goes appropriately to zero with the density. Although considerable modification is required, Saha theory is closer to the actual results for this case than is Thomas-Fermi theory.

  12. Density functionals from deep learning

    NASA Astrophysics Data System (ADS)

    McMahon, Jeffrey

    Density-functional theory is a formally exact description of a many-body quantum system in terms of its density; in practice, however, approximations to the universal density functional (DF) are necessary. Machine learning has recently been proposed as a novel approach to discover such a DF (or components of it). Conventional machine learning algorithms, however, are limited in their ability to process data in their raw form, leading to invariance and/or sensitivity issues. In this presentation, an alternative approach based on deep learning will be demonstrated. Deep learning allows computational models that are capable of discovering intricate structure in large and/or high-dimensional data sets with multiple levels of abstraction, and do not suffer from the aforementioned issues. Results from the application of this approach to the prediction of the kinetic-energy DF of noninteracting electrons will be presented. Using theoretical results from computer science, a connection between the underlying model and the theorems of Hohenberg and Kohn will also be suggested.

  13. Stringy holography at finite density

    NASA Astrophysics Data System (ADS)

    Goykhman, Mikhail; Parnachev, Andrei

    2013-09-01

    We consider an exactly solvable worldsheet string theory in the background of a black brane with a gauge field flux. Holographically, such a system can be interpreted as a field theory with finite number of degrees of freedom at finite temperature and density. This is to be contrasted with more conventional holographic models which involve gravity in the bulk and possess infinite number of degrees of freedom and mean field critical exponents. We construct closed string vertex operators which holographically represent the U(1) gauge field and the stress-energy tensor and compute their two-point functions. At finite temperature and vanishing charge density the low-energy excitations are described by hydrodynamics. As the density is raised, the system behaves like a sum of two non-interacting fluids. We find low-energy excitations in the shear and sound channels of each fluid. We thank A. Giveon for pointing out to us the role of this equation in the 2d charged black hole solution of type-II superstring theory.

  14. Spatially revolved high density electroencephalography

    NASA Astrophysics Data System (ADS)

    Wu, Jerry; Szu, Harold; Chen, Yuechen; Guo, Ran; Gu, Xixi

    2015-05-01

    Electroencephalography (EEG) measures voltage fluctuations resulting from ionic current flows within the neurons of the brain. In practice, EEG refers to the recording of the brain's spontaneous electrical activity over a short period of time, several tens of minutes, as recorded from multiple electrodes placed on the scalp. In order to improve the resolution and the distortion cause by the hair and scalp, large array magnetoencephalography (MEG) systems are introduced. The major challenge is to systematically compare the accuracy of epileptic source localization with high electrode density to that obtained with sparser electrode setups. In this report, we demonstrate a two dimension (2D) image Fast Fourier Transform (FFT) analysis along with utilization of Peano (space-filling) curve to further reduce the hardware requirement for high density EEG and improve the accuracy and performance of the high density EEG analysis. The brain-computer interfaces (BCIs) in this work is enhanced by A field-programmable gate array (FPGA) board with optimized two dimension (2D) image Fast Fourier Transform (FFT) analysis.

  15. Electron Density and Capacitance at the interface of Au-ZnO Based Schottky Diode

    NASA Astrophysics Data System (ADS)

    Wu, Chin-Sheng

    ZnO with wide direct band gap (3.37 eV) is a well-known and an interesting compound semiconducting material, which have been used for the fabrication of optical, electrical, and piezoelectric devices such as light emitting diodes, solar cells. Schottky diodes are associated with quicker switching and lower turn on voltages compared to p-n junction diodes. J-V characteristics exhibit nonlinear rectifying behavior with threshold voltage of 2.1 V. The barrier heights were found to be 0.61 eV. The measured capacitance for the Schottky junction depends on the reverse bias potential and frequency. At the lower frequencies the capacitance has the higher values due to the trapping occurred at the interface through the surface roughness and lattice mismatch. We perform model potential calculation with quantum well around the interface. Model potentials allow some degree of freedom in the design of the emitted wavelength through adjustment of the energy levels. We apply the various well width w and barrier height V in order to match the device information made by Willander. Solving the Schrödinger equation with exchange- correlation energy and effective mass of electrons will produce values of the energy levels and states. The variational barrier heights result in the change of the electron density This accounts for the excessive capacitance at the interface of Schottky diode.

  16. Density variations and anomalies in palladium compacts

    SciTech Connect

    Back, D.; Jones, T.; Ransick, M.; Walburg, T.; Werkmeister, D.

    1992-05-14

    Low-density compacts of palladium powder have relative densities of about 30{plus_minus}10% TD. The variations in density are of concern for operations such as chemical/hydrogen pump systems because heat, mass, and momentum transport properties can be affected. Variations in density result from the inherent nature and interacting forces of UASA compaction of powder in cylinders. In addition to these expected variations, discontinuous density anomalies, such as cracks or high density ridges, are also found. An anomaly of particular concern was found to resemble a ``steer`s head.`` it is a symmetrical region of low density located at or near the center of a compact. Typically, this region is surrounded by a band of high density, compacted palladium that sometimes exceeds the density of the surrounding compact matrix by a factor of three. This report examines these density variations and anomalies both theoretically and empirically.

  17. Density variations and anomalies in palladium compacts

    SciTech Connect

    Back, D.; Jones, T.; Ransick, M.; Walburg, T.; Werkmeister, D.

    1992-05-14

    Low-density compacts of palladium powder have relative densities of about 30{plus minus}10% TD. The variations in density are of concern for operations such as chemical/hydrogen pump systems because heat, mass, and momentum transport properties can be affected. Variations in density result from the inherent nature and interacting forces of UASA compaction of powder in cylinders. In addition to these expected variations, discontinuous density anomalies, such as cracks or high density ridges, are also found. An anomaly of particular concern was found to resemble a steer's head.'' it is a symmetrical region of low density located at or near the center of a compact. Typically, this region is surrounded by a band of high density, compacted palladium that sometimes exceeds the density of the surrounding compact matrix by a factor of three. This report examines these density variations and anomalies both theoretically and empirically.

  18. Densities and temperatures in the polar thermosphere

    NASA Technical Reports Server (NTRS)

    Gardner, L. J.

    1977-01-01

    The atomic oxygen density at 120 km, the 630 nm airglow temperature, the helium density at 300 km and the molecular nitrogen density near 400 km were examined as functions of geomagnetic latitude, geomagnetic time, season and magnetic activity level. The long-term averages of these quantities were examined so as to provide a baseline of these thermospheric parameters from which future studies may be made for comparison. The hours around magnetic noon are characterized by low temperatures, high 0 and He densities, and median nitrogen densities. The pre-midnight hours exhibit high temperatures, high He density, low nitrogen density and median 0 densities. The post-midnight sector shows low 0 and He densities, median temperatures and high nitrogen densities. These results are compared to recent models and observations and are discussed with respect to their causes due to divergence of the wind field and energy deposition in the thermosphere.

  19. DENSITY CONTROL IN A REACTOR

    DOEpatents

    Marshall, J. Jr.

    1961-10-24

    A reactor is described in which natural-uranium bodies are located in parallel channels which extend through the graphite mass in a regular lattice. The graphite mass has additional channels that are out of the lattice and contain no uranium. These additional channels decrease in number per unit volume of graphite from the center of the reactor to the exterior and have the effect of reducing the density of the graphite more at the center than at the exterior, thereby spreading neutron activity throughout the reactor. (AEC)

  20. High-Energy-Density Capacitors

    NASA Technical Reports Server (NTRS)

    Slenes, Kirk

    2003-01-01

    Capacitors capable of storing energy at high densities are being developed for use in pulse-power circuits in such diverse systems as defibrillators, particle- beam accelerators, microwave sources, and weapons. Like typical previously developed energy-storage capacitors, these capacitors are made from pairs of metal/solid-dielectric laminated sheets that are wound and pressed into compact shapes to fit into cans, which are then filled with dielectric fluids. Indeed, these capacitors can be fabricated largely by conventional fabrication techniques. The main features that distinguish these capacitors from previously developed ones are improvements in (1) the selection of laminate materials, (2) the fabrication of the laminated sheets from these materials, and (3) the selection of dielectric fluids. In simplest terms, a high-performance laminated sheet of the type used in these capacitors is made by casting a dielectric polymer onto a sheet of aluminized kraft paper. The dielectric polymer is a siloxane polymer that has been modified with polar pendant groups to increase its permittivity and dielectric strength. Potentially, this polymer is capable of withstanding an energy density of 7.5 J/cm3, which is four times that of the previous state-of-the-art-capacitor dielectric film material. However, the full potential of this polymer cannot be realized at present because (1) at thicknesses needed for optimum performance (.8.0 m), the mechanical strength of a film of this polymer is insufficient for incorporation into a wound capacitor and (2) at greater thickness, the achievable energy density decreases because of a logarithmic decrease in dielectric strength with increasing thickness. The aluminized kraft paper provides the mechanical strength needed for processing of the laminate and fabrication of the capacitor, and the aluminum film serves as an electrode layer. Because part of the thickness of the dielectric is not occupied by the modified siloxane polymer, the

  1. High-density digital recording

    NASA Technical Reports Server (NTRS)

    Kalil, F. (Editor); Buschman, A. (Editor)

    1985-01-01

    The problems associated with high-density digital recording (HDDR) are discussed. Five independent users of HDDR systems and their problems, solutions, and insights are provided as guidance for other users of HDDR systems. Various pulse code modulation coding techniques are reviewed. An introduction to error detection and correction head optimization theory and perpendicular recording are provided. Competitive tape recorder manufacturers apply all of the above theories and techniques and present their offerings. The methodology used by the HDDR Users Subcommittee of THIC to evaluate parallel HDDR systems is presented.

  2. QCD AT HIGH PARTON DENSITY

    SciTech Connect

    KOVCHEGOV,Y.V.

    2000-04-25

    The authors derive an equation determining the small-x evolution of the F{sub 2} structure function of a large nucleus which resumes a cascade of gluons in the leading logarithmic approximation using Mueller's color dipole model. In the traditional language it corresponds to resummation of the pomeron fan diagrams, originally conjectured in the GLR equation. The authors show that the solution of the equation describes the physics of structure functions at high partonic densities, thus allowing them to gain some understanding of the most interesting and challenging phenomena in small-x physics--saturation.

  3. A novel graded density impactor

    NASA Astrophysics Data System (ADS)

    Winter, Ron; Cotton, Matthew; Harris, Ernest; Eakins, Daniel; Chapman, David

    2013-06-01

    Ramp loading using graded-density-impactors as flyers in plate impact experiments can yield useful information about the dynamic properties of the loaded material. Selective Laser Melting, an additive manufacture technique, was used to fabricate a graded-density flyer, termed the ``bed of nails'' (BON). A 2 mm thick x 100 mm diameter solid disc of stainless steel formed a base for an array of tapered spikes of length 6 mm and spaced 1 mm apart. Two experiments to test the concept were performed at impact velocities of 900 m/s and 1100 m/s using the 100 mm gas gun at The Institute of Shock Physics, Imperial College, London. In each experiment a BON flyer was impacted onto a copper buffer plate which helped to smooth out perturbations in the wave profile. The ramp delivered to the copper buffer was in turn transmitted to three tantalum targets of thicknesses 3, 5 and 7 mm, mounted in contact with the back face of the copper. Heterodyne velocimetry was used to measure the velocity-time history, at the back faces of the tantalum discs. The wave profiles display a smooth increase in free surface velocity over a period of about 2.5 microseconds. The measured profiles have been analysed to generate a stress vs. volume curve for tantalum.

  4. A novel graded density impactor

    NASA Astrophysics Data System (ADS)

    Winter, R. E.; Cotton, M.; Harris, E. J.; Chapman, D. J.; Eakins, D.

    2014-05-01

    Ramp loading using graded-density-impactors as flyers in gas-gun-driven plate impact experiments can yield new and useful information about the equation of state and the strength properties of the loaded material. Selective Laser Melting, an additive manufacture technique, was used to manufacture a graded density flyer, termed the "bed of nails" (BON). A 2 mm thick × 100 mm diameter solid disc of stainless steel formed a base for an array of tapered spikes of length 6 mm and spaced 1 mm apart. The two experiments to test the concept were performed at impact velocities of 900 m/s and 1100 m/s using the 100 mm gas gun at the Institute of Shock Physics at Imperial College, London. In each experiment a BON flyer was impacted onto a copper buffer plate which helped to smooth out perturbations in the wave profile. The ramp delivered to the copper buffer was in turn transmitted to three tantalum targets of thicknesses 3, 5 and 7 mm, which were mounted in contact with the back face of the copper. Heterodyne velocimetry was used to measure the velocity-time history, at the back faces of the tantalum discs. The wave profiles display a smooth increase in velocity over a period of ~2.5 us, with no indication of a shock jump. The measured profiles have been analysed to generate a stress strain curve for tantalum. The results have been compared with the predictions of the Sandia National Laboratories hydrocode, CTH.

  5. Direct analytical method of contact position effects on the energy-level alignments at organic semiconductor/electrode interfaces using photoemission spectroscopy combined with Ar gas cluster ion beam sputtering

    NASA Astrophysics Data System (ADS)

    Yun, Dong-Jin; Chung, JaeGwan; Kim, Seong Heon; Kim, Yongsu; Park, SungHoon; Seol, Minsu; Heo, Sung

    2015-11-01

    Poly(3, 4-ethylenedioxythiophene) (PEDOT) polymerized with poly(4-styrenesulfonate) (PSS) is one of the most widely used conducting organic electrodes owing to its outstanding optical/electrical properties and high work function. Because its work function depends significantly on the molecular arrangements between PEDOT and PSS molecules on the surface, the contact position of PEDOT:PSS films on organic semiconductors (OSCs) must also be an essential consideration. However, existing analysis methods based on in situ deposition/analysis are limited in their ability to accurately investigate the electronic structures of the buried interface regions under the solution-processed electrode or OSC layer in organic devices. Therefore, to overcome such limitations, we propose a top-down method based on photoemission spectroscopy analysis combined with Ar gas cluster ion beam (GCIB) sputtering. Through this method, both energy-level alignments and molecular distributions at various OSC/electrode interfaces can be successfully characterized without reference to any deposition process.

  6. Response to ``Comment on `Spectra and energy levels of Er3+(4f11) in NaBi(WO4)2' '' [J. Appl. Phys. 96, 4656 (2004)

    NASA Astrophysics Data System (ADS)

    Gruber, John B.

    2004-10-01

    We present a reply to the preceding comment made by C. Cascales and C. Zaldo concerning an analysis of the "Spectra and energy levels of Er3+(4f11) in NaBi(WO4)2" [J. Appl. Phys. 94, 7128 (2003)] by J. B. Gruber, Department of Physics, San José State University, San Jose, CA 95192-0106; D. K. Sardar, C. C. Russell III, and R. M. Yow, Department of Physics and Astronomy, University of Texas at San Antonio, San Antonio, Texas 78249-0063, B. Zandi, ARL/Adelph Laboratory Center, 2800 Powder Mill Road, Adelphi, Maryland 20783-1197; and E. P. Kokanyan, Institute for Physical Research, Armenian National Academy of Sciences, Ashtarak, Armenia 378410.

  7. Calculation of vibrational energy levels of triatomic molecules with the C 2v and C s symmetries by summing divergent series of the Rayleigh-Schrödinger perturbation theory

    NASA Astrophysics Data System (ADS)

    Bykov, A. D.; Kalinin, K. V.

    2012-03-01

    The Rayleigh-Schrödinger perturbation theory is applied to calculation of vibrational energy levels of triatomic molecules with the C 2v and C s symmetries: SO2, H2S, F2O, HOF, HOCl, and DOCl. Particular attention is given to the states coupled by anharmonic resonances; for such states, the perturbation theory series diverge. To sum these series, the known methods of Padé, Padé-Borel, and Padé-Hermite and the method of power moments are used. For low-lying levels, all the summation methods give satisfactory results, while the method of quadratic Padé-Hermite approximants appears to be more efficient for high-excited states. Using these approximants, the structure of singularities of the vibrational energy, as a function in the complex plane, is studied.

  8. Copper impurities in bulk ZnO: A hybrid density functional study

    NASA Astrophysics Data System (ADS)

    Gallino, Federico; Di Valentin, Cristiana

    2011-04-01

    Transition metal doping of ZnO is considered as a promising way to obtain a diluted magnetic semiconducting oxide. In this work we investigate copper doping of ZnO by means of density functional theory, using a hybrid exchange-correlation functional and a periodic approach with localized atomic basis functions. Isolated copper species, such as copper substitutional to zinc, Cus, and Cu interstitial, Cui, are analyzed in terms of transition energy levels and hyperfine coupling constants with reference to available spectroscopic data. We also examine the potential magnetic interaction between copper species, their interaction with oxygen vacancies, and the possibility of copper clustering. The relative stability of the various copper impurities considered in this study is finally compared on the basis of their formation energy at different oxygen chemical potentials and Fermi level values.

  9. Energy Levels of Coupled Plasmonic Cavities

    NASA Astrophysics Data System (ADS)

    Liu, Chuan-Pu; Zhu, Xin-Li; Zhang, Jia-Sen; Xu, Jun; Leprince-Wang, Yamin; Yu, Da-Peng

    2016-08-01

    Not Available Supported by the National Basic Research Program of China under Grant No 2013CB932602, and the National Natural Science Foundation of China under Grant Nos 11574011, 61377050 and 11234001.

  10. Energy levels of HoBr 63-

    NASA Astrophysics Data System (ADS)

    Tanner, Peter A.

    1986-12-01

    The excitation, electronic absorption and luminescence spectra of cubic Cs 2NaHoBr 6 have been recorded at temperatures down to that of liquid helium. The detailed spectral analyses enable comparisons to be made of the crystal-field splittings of Russell—Saunders terms with those in Cs 2NaHoCl 6. Under intense 647.1 nm laser excitation, luminescence is observed in the neat material in the spectral region between 17800 and 21750 cm -1.

  11. Electronic structure evolution and energy level alignment at C{sub 60}/4,4′-cyclohexylidenebis[N,N-bis(4-methylphenyl) benzenamine]/MoO{sub x}/indium tin oxide interfaces

    SciTech Connect

    Liu, Xiaoliang; Yi, Shijuan; Wang, Chenggong; Wang, Congcong; Gao, Yongli

    2014-04-28

    The electronic structure evolution and energy level alignment have been investigated at interfaces comprising fullerene (C{sub 60})/4,4′-cyclohexylidenebis[N,N-bis(4-methylphenyl) benzenamine] (TAPC)/ molybdenum oxide (MoO{sub x})/ indium tin oxide with ultraviolet photoemission spectroscopy and inverse photoemission spectroscopy. With deposition of TAPC upon MoO{sub x}, a dipole of 1.58 eV was formed at the TAPC/MoO{sub x} interface due to electron transfer from TAPC to MoO{sub x}. The highest occupied molecular orbital (HOMO) onset of TAPC was pinned closed to the Fermi level, leading to a p-doped region and thus increasing the carrier concentration at the very interface. The downward band bending and the resulting built-in field in TAPC were favorable for the hole transfer toward the TAPC/MoO{sub x} interface. The rigid downward shift of energy levels of TAPC indicated no significant interface chemistry at the interface. With subsequent deposition of C{sub 60} on TAPC, a dipole of 0.27 eV was observed at the C{sub 60}/TAPC heterojunction due to the electron transfer from TAPC to C{sub 60}. This led to a drop of the HOMO of TAPC near the C{sub 60}/TAPC interface, and hence further enhanced the band bending in TAPC. The band bending behavior was also observed in C{sub 60}, similarly creating a built-in field in C{sub 60} film and improving the electron transfer away from the C{sub 60}/TAPC interface. It can be deduced from the interface analysis that a promising maximum open circuit voltage of 1.5 eV is achievable in C{sub 60}/TAPC-based organic photovoltaic cells.

  12. Density functional theory: Foundations reviewed

    NASA Astrophysics Data System (ADS)

    Kryachko, Eugene S.; Ludeña, Eduardo V.

    2014-11-01

    Guided by the above motto (quotation), we review a broad range of issues lying at the foundations of Density Functional Theory, DFT, a theory which is currently omnipresent in our everyday computational study of atoms and molecules, solids and nano-materials, and which lies at the heart of modern many-body computational technologies. The key goal is to demonstrate that there are definitely the ways to improve DFT. We start by considering DFT in the larger context provided by reduced density matrix theory (RDMT) and natural orbital functional theory (NOFT), and examine the implications that N-representability conditions on the second-order reduced density matrix (2-RDM) have not only on RDMT and NOFT but, also, by extension, on the functionals of DFT. This examination is timely in view of the fact that necessary and sufficient N-representability conditions on the 2-RDM have recently been attained. In the second place, we review some problems appearing in the original formulation of the first Hohenberg-Kohn theorem which is still a subject of some controversy. In this vein we recall Lieb's comment on this proof and the extension to this proof given by Pino et al. (2009), and in this context examine the conditions that must be met in order that the one-to-one correspondence between ground-state densities and external potentials remains valid for finite subspaces (namely, the subspaces where all Kohn-Sham solutions are obtained in practical applications). We also consider the issue of whether the Kohn-Sham equations can be derived from basic principles or whether they are postulated. We examine this problem in relation to ab initio DFT. The possibility of postulating arbitrary Kohn-Sham-type equations, where the effective potential is by definition some arbitrary mixture of local and non-local terms, is discussed. We also deal with the issue of whether there exists a universal functional, or whether one should advocate instead the construction of problem

  13. The local dark matter density

    NASA Astrophysics Data System (ADS)

    Read, J. I.

    2014-06-01

    I review current efforts to measure the mean density of dark matter near the Sun. This encodes valuable dynamical information about our Galaxy and is also of great importance for ‘direct detection’ dark matter experiments. I discuss theoretical expectations in our current cosmology; the theory behind mass modelling of the Galaxy; and I show how combining local and global measures probes the shape of the Milky Way dark matter halo and the possible presence of a ‘dark disc’. I stress the strengths and weaknesses of different methodologies and highlight the continuing need for detailed tests on mock data—particularly in the light of recently discovered evidence for disequilibria in the Milky Way disc. I collate the latest measurements of ρdm and show that, once the baryonic surface density contribution Σb is normalized across different groups, there is remarkably good agreement. Compiling data from the literature, I estimate Σb = 54.2 ± 4.9 M⊙pc-2, where the dominant source of uncertainty is in the H i gas contribution. Assuming this contribution from the baryons, I highlight several recent measurements of ρdm in order of increasing data complexity and prior, and, correspondingly, decreasing formal error bars. Comparing these measurements with spherical extrapolations from the Milky Way’s rotation curve, I show that the Milky Way is consistent with having a spherical dark matter halo at R0 ˜ 8 kpc. The very latest measures of ρdm based on ˜10 000 stars from the Sloan Digital Sky Survey appear to favour little halo flattening at R0, suggesting that the Galaxy has a rather weak dark matter disc, with a correspondingly quiescent merger history. I caution, however, that this result hinges on there being no large systematics that remain to be uncovered in the SDSS data, and on the local baryonic surface density being Σb ˜ 55 M⊙pc-2. I conclude by discussing how the new Gaia satellite will be transformative. We will obtain much tighter

  14. High density tape casting system

    NASA Technical Reports Server (NTRS)

    Collins, Earl R., Jr. (Inventor)

    1989-01-01

    A system is provided for casting thin sheets (or tapes) of particles bound together, that are used for oxygen membranes and other applications, which enables the particles to be cast at a high packing density in a tape of uniform thickness. A slurry contains the particles, a binder, and a solvent, and is cast against the inside walls of a rotating chamber. Prior to spraying the slurry against the chamber walls, a solvent is applied to a container. The solvent evaporates to saturate the chamber with solvent vapor. Only then is the slurry cast. As a result, the slurry remains fluid long enough to spread evenly over the casting surface formed by the chamber, and for the slurry particles to become densely packed. Only then is the chamber vented to remove solvent, so the slurry can dry. The major novel feature is applying solvent vapor to a rotating chamber before casting slurry against the chamber walls.

  15. High power density spray cooling

    NASA Astrophysics Data System (ADS)

    Tilton, Donald E.; Pais, Martin R.; Chow, Louis C.

    1989-07-01

    The research reported describes experimental and theoretical investigations of high power density evaporative spray cooling. Preliminary experiments demonstrating heat fluxes greater than 1,000 W/sq cm were conducted. Extensive laser phase Doppler measurements of spray characteristics were also taken. These measurements provided valuable insight into the heat transfer process. An in-depth analysis was conducted to determine the mechanisms responsible for critical heat flux. Theoretical modeling was also conducted to determine the most desirable heat transfer conditions. After analysis of these results, an improved experimental apparatus was designed and fabricated. The new apparatus provided greater experimental control and improve accuracy. New tests were conducted in which the critical heat flux was increased, and the heat transfer efficiency was greatly improved. These results are compared to those of previous researchers, and indicated substantial improvement.

  16. Oxides having high energy densities

    DOEpatents

    Ceder, Gerbrand; Kang, Kisuk

    2013-09-10

    Certain disclosed embodiments generally relate to oxide materials having relatively high energy and/or power densities. Various aspects of the embodiments are directed to oxide materials having a structure B.sub.i(M.sub.jY.sub.k)O.sub.2, for example, a structure Li.sub.j(Ni.sub.jY.sub.k)O.sub.2 such as Li(Ni.sub.0.5Mn.sub.0.5)O.sub.2. In this structure, Y represents one or more atoms, each independently selected from the group consisting of alkaline earth metals, transition metals, Group 14 elements, Group 15, or Group 16 elements. In some embodiments, such an oxide material may have an O3 crystal structure, and/or a layered structure such that the oxide comprises a plurality of first, repeating atomic planes comprising Li, and a plurality of second, repeating atomic planes comprising Ni and/or Y.

  17. LATTICE QCD AT FINITE DENSITY.

    SciTech Connect

    SCHMIDT, C.

    2006-07-23

    I discuss different approaches to finite density lattice QCD. In particular, I focus on the structure of the phase diagram and discuss attempts to determine the location of the critical end-point. Recent results on the transition line as function of the chemical potential (T{sub c}({mu}{sub q})) are reviewed. Along the transition line, hadronic fluctuations have been calculated; which can be used to characterize properties of the Quark Gluon plasma and eventually can also help to identify the location of the critical end-point in the QCD phase diagram on the lattice and in heavy ion experiments. Furthermore, I comment on the structure of the phase diagram at large {mu}{sub q}.

  18. Information Density and Syntactic Repetition.

    PubMed

    Temperley, David; Gildea, Daniel

    2015-11-01

    In noun phrase (NP) coordinate constructions (e.g., NP and NP), there is a strong tendency for the syntactic structure of the second conjunct to match that of the first; the second conjunct in such constructions is therefore low in syntactic information. The theory of uniform information density predicts that low-information syntactic constructions will be counterbalanced by high information in other aspects of that part of the sentence, and high-information constructions will be counterbalanced by other low-information components. Three predictions follow: (a) lexical probabilities (measured by N-gram probabilities and head-dependent probabilities) will be lower in second conjuncts than first conjuncts; (b) lexical probabilities will be lower in matching second conjuncts (those whose syntactic expansions match the first conjunct) than nonmatching ones; and (c) syntactic repetition should be especially common for low-frequency NP expansions. Corpus analysis provides support for all three of these predictions. PMID:25557056

  19. Simulation Of Wave Function And Probability Density Of Modified Poschl Teller Potential Derived Using Supersymmetric Quantum Mechanics

    SciTech Connect

    Angraini, Lily Maysari; Suparmi,; Variani, Viska Inda

    2010-12-23

    SUSY quantum mechanics can be applied to solve Schrodinger equation for high dimensional system that can be reduced into one dimensional system and represented in lowering and raising operators. Lowering and raising operators can be obtained using relationship between original Hamiltonian equation and the (super) potential equation. In this paper SUSY quantum mechanics is used as a method to obtain the wave function and the energy level of the Modified Poschl Teller potential. The graph of wave function equation and probability density is simulated by using Delphi 7.0 programming language. Finally, the expectation value of quantum mechanics operator could be calculated analytically using integral form or probability density graph resulted by the programming.

  20. Simulation Of Wave Function And Probability Density Of Modified Poschl Teller Potential Derived Using Supersymmetric Quantum Mechanics

    NASA Astrophysics Data System (ADS)

    Angraini, Lily Maysari; Suparmi, Variani, Viska Inda

    2010-12-01

    SUSY quantum mechanics can be applied to solve Schrodinger equation for high dimensional system that can be reduced into one dimensional system and represented in lowering and raising operators. Lowering and raising operators can be obtained using relationship between original Hamiltonian equation and the (super) potential equation. In this paper SUSY quantum mechanics is used as a method to obtain the wave function and the energy level of the Modified Poschl Teller potential. The graph of wave function equation and probability density is simulated by using Delphi 7.0 programming language. Finally, the expectation value of quantum mechanics operator could be calculated analytically using integral form or probability density graph resulted by the programming.

  1. Broken symmetry approach to density functional calculation of magnetic anisotropy or zero field splittings for multinuclear complexes with antiferromagnetic coupling.

    PubMed

    van Wüllen, Christoph

    2009-10-29

    Antiferromagnetic coupling in multinuclear transition metal complexes usually leads to electronic ground states that cannot be described by a single Slater determinant and that are therefore difficult to describe by Kohn-Sham density functional methods. Density functional calculations in such cases are usually converged to broken symmetry solutions which break spin and, in many cases, also spatial symmetry. While a procedure exists to extract isotropic Heisenberg (exchange) coupling constants from such calculations, no such approach is yet established for the calculation of magnetic anisotropy energies or zero field splitting parameters. This work proposes such a procedure. The broken symmetry solutions are not only used to extract the exchange couplings but also single-ion D tensors which are then used to construct a (phenomenological) spin Hamiltonian, from which the magnetic anisotropy and the zero-field energy levels can be computed. The procedure is demonstrated for a bi- and a trinuclear Mn(III) model compound. PMID:19708660

  2. Atomic nitrogen densities near the polar cusp

    NASA Technical Reports Server (NTRS)

    Engebretson, M. J.; Nelson, J. T.

    1986-01-01

    The neutral atmospheric composition spectrometer on board the Dynamics Explorer 2 spacecraft sampled several major and minor thermospheric gases including atomic nitrogen. A selection of passes over the polar cusp that provide a quantitative measure of N densities in this region and provide evidence of localized density increases due to soft particle precipitation is presented. Increases in N densities are frequently observed but are smaller than accompanying increases in N2 densities. The observations support earlier studies suggesting that N densities increase more rapidly than O densities during periods of high solar EUV flux and N densities are larger in the summer hemisphere than in the winter hemisphere. A series of passes in February 1983, late in the lifetime of DE 2, indicated N densities at 200 km altitude were a factor of 2 larger near the southern cusp than near the northern cusp.

  3. Atomic nitrogen densities near the polar cusp

    NASA Technical Reports Server (NTRS)

    Engebretson, M. J.; Nelson, J. T.

    1985-01-01

    The neutral atmospheric composition spectrometer on board the Dynamics Explorer 2 spacecraft sampled several major and minor thermospheric gases including atomic nitrogen. A selection of passes over the polar cusp that provide a quantitative measure of N densities in this region and provide evidence of localized density increases due to soft particle precipitation is presented. Increases in N densities are frequently observed but are smaller than accompanying increases in N2 densities. The observations support earlier studies suggesting that (1) N densities increase more rapidly than O densities during periods of high solar EUV flux and (2) N densities are larger in the summer hemisphere than in the winter hemisphere. A series of passes in February 1983, late in the lifetime of DE 2, indicated N densities at 200 km altitude were a factor of 2 larger near the southern cusp than near the northern cusp.

  4. Bone Density Testing (Beyond the Basics)

    MedlinePlus

    ... of Use ©2016 UpToDate, Inc. Patient education: Bone density testing (Beyond the Basics) Author Michael Kleerekoper, MD ... last updated: Sep 22, 2015. WHAT DOES BONE DENSITY TESTING DO AND WHY IS IT IMPORTANT? — People ...

  5. Breast Density and Your Breast Mammogram Report

    MedlinePlus

    Breast Density and Your Mammogram Report Regular mammograms are the best way to find breast cancer early. But if ... But in some women, there’s little change. Breast density is very common, and is not abnormal. How ...

  6. Electronic structures and optical properties of TiO2: Improved density-functional-theory investigation

    NASA Astrophysics Data System (ADS)

    Gong, Sai; Liu, Bang-Gui

    2012-05-01

    TiO2 has been recently used to realize high-temperature ferromagnetic semiconductors. In fact, it has been widely used for a long time as white pigment and sunscreen because of its whiteness, high refractive index, and excellent optical properties. However, its electronic structures and the related properties have not been satisfactorily understood. Here, we use Tran and Blaha's modified Becke-Johnson (TB-mBJ) exchange potential (plus a local density approximation correlation potential) within the density functional theory to investigate electronic structures and optical properties of rutile and anatase TiO2. Our comparative calculations show that the energy gaps obtained from mBJ method agree better with the experimental results than that obtained from local density approximation (LDA) and generalized gradient approximation (GGA), in contrast with substantially overestimated values from many-body perturbation (GW) calculations. As for optical dielectric functions (both real and imaginary parts), refractive index, and extinction coefficients as functions of photon energy, our mBJ calculated results are in excellent agreement with the experimental curves. Our further analysis reveals that these excellent improvements are achieved because mBJ potential describes accurately the energy levels of Ti 3d states. These results should be helpful to understand the high temperature ferromagnetism in doped TiO2. This approach can be used as a standard to understand electronic structures and the related properties of such materials as TiO2.

  7. The dynamics of variable-density turbulence

    SciTech Connect

    Sandoval, D.L.

    1995-11-01

    The dynamics of variable-density turbulent fluids are studied by direct numerical simulation. The flow is incompressible so that acoustic waves are decoupled from the problem, and implying that density is not a thermodynamic variable. Changes in density occur due to molecular mixing. The velocity field, is in general, divergent. A pseudo-spectral numerical technique is used to solve the equations of motion. Three-dimensional simulations are performed using a grid size of 128{sup 3} grid points. Two types of problems are studied: (1) the decay of isotropic, variable-density turbulence, and (2) buoyancy-generated turbulence in a fluid with large density fluctuations. In the case of isotropic, variable-density turbulence, the overall statistical decay behavior, for the cases studied, is relatively unaffected by the presence of density variations when the initial density and velocity fields are statistically independent. The results for this case are in quantitative agreement with previous numerical and laboratory results. In this case, the initial density field has a bimodal probability density function (pdf) which evolves in time towards a Gaussian distribution. The pdf of the density field is symmetric about its mean value throughout its evolution. If the initial velocity and density fields are statistically dependent, however, the decay process is significantly affected by the density fluctuations. For the case of buoyancy-generated turbulence, variable-density departures from the Boussinesq approximation are studied. The results of the buoyancy-generated turbulence are compared with variable-density model predictions. Both a one-point (engineering) model and a two-point (spectral) model are tested against the numerical data. Some deficiencies in these variable-density models are discussed and modifications are suggested.

  8. Record high Wolf, Canis lupus, pack density

    USGS Publications Warehouse

    Mech, L.D.; Tracy, S.

    2004-01-01

    This report documents a year-around Wolf (Canis lupus) density of 18.2/100 km2 and a summer density of 30.8/100 km2, in a northeastern Minnesota Wolf pack. The previous record was a summer density of 14.1/100 km2, for a Wolf pack on Vancouver Island, British Columbia, Canada.

  9. Record high wolf, Canis lupus, pack density

    USGS Publications Warehouse

    Mech, L.D.; Tracy, S.

    2004-01-01

    This report documents a year-around wolf (Canis lupus) density of 18.2/100 m2 and summer density of 30.8/100 km2, in a northeastern Minnesota wolf pack. The previous record was a summer density of 14.1/100 km2, for a wolf pack on Vancouver Island, BC, Canada.

  10. 36 CFR 910.12 - Development density.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 36 Parks, Forests, and Public Property 3 2012-07-01 2012-07-01 false Development density. 910.12... DEVELOPMENT AREA Urban Planning and Design Concerns § 910.12 Development density. (a) Land would be developed... density within the building envelope delineated by specific height restrictions, but shall also...

  11. 36 CFR 910.12 - Development density.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 36 Parks, Forests, and Public Property 3 2011-07-01 2011-07-01 false Development density. 910.12... DEVELOPMENT AREA Urban Planning and Design Concerns § 910.12 Development density. (a) Land would be developed... density within the building envelope delineated by specific height restrictions, but shall also...

  12. 36 CFR 910.12 - Development density.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 36 Parks, Forests, and Public Property 3 2010-07-01 2010-07-01 false Development density. 910.12... DEVELOPMENT AREA Urban Planning and Design Concerns § 910.12 Development density. (a) Land would be developed... density within the building envelope delineated by specific height restrictions, but shall also...

  13. 36 CFR 910.12 - Development density.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 36 Parks, Forests, and Public Property 3 2013-07-01 2012-07-01 true Development density. 910.12... DEVELOPMENT AREA Urban Planning and Design Concerns § 910.12 Development density. (a) Land would be developed... density within the building envelope delineated by specific height restrictions, but shall also...

  14. 36 CFR 910.12 - Development density.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 36 Parks, Forests, and Public Property 3 2014-07-01 2014-07-01 false Development density. 910.12... DEVELOPMENT AREA Urban Planning and Design Concerns § 910.12 Development density. (a) Land would be developed... density within the building envelope delineated by specific height restrictions, but shall also...

  15. The dynamics of variable-density turbulence

    SciTech Connect

    Sandoval, D.L.

    1995-11-01

    The dynamics of variable-density turbulent fluids are studied by direct numerical simulation. The flow is incompressible so that acoustic waves are decoupled from the problem, and implying that density is not a thermodynamic variable. Changes in density occur due to molecular mixing. The velocity field is, in general, divergent. A pseudo-spectral numerical technique is used to solve the equations of motion. Three-dimensional simulations are performed using a grid size of 128{sup 3} grid points. Two types of problems are studied: (1) the decay of isotropic, variable-density turbulence, and (2) buoyancy-generated turbulence in a fluid with large density fluctuations (such that the Boussinesq approximation is not valid). In the case of isotropic, variable-density turbulence, the overall statistical decay behavior, for the cases studied, is relatively unaffected by the presence of density variations when the initial density and velocity fields are statistically independent. The results for this case are in quantitative agreement with previous numerical and laboratory results. In this case, the initial density field has a bimodal probability density function (pdf) which evolves in time towards a Gaussian distribution. The pdf of the density field is symmetric about its mean value throughout its evolution. If the initial velocity and density fields are statistically dependent, however, the decay process is significantly affected by the density fluctuations. For this case, the pdf of the density becomes asymmetric about its mean value during the early stages of its evolution. It is argued that these asymmetries in the pdf of the density field are due to different entrainment rates, into the mixing region, that favor the high speed fluid.

  16. Surfing the High Density Universe

    NASA Technical Reports Server (NTRS)

    Helfand, David J.

    1998-01-01

    The central theme of the proposed research is to link what we know about galaxy clusters and large-scale structure in the local Universe at z less than 0.1 to what we know about the original fluctuations that led to this structure as observed in the cosmic microwave background. The simple-minded approach to this question (the kind I always take) is to took at structure in the regime 0.1 less than z less than 1000. We have a unique resource to help us in this task in the form of the VLA FIRST radio survey in which, to date, we have completed mapping nearly 5000 deg2 of the northern sky to a 20 cm flux density limit of 1.0 mJy. The 435,000 radio sources detected all have positions accurate to better than 1. As this report is written, we are obtaining the next - 1000 deg 2 of data; the goal of the survey is to complete the full 10,000 deg 2 to be covered in the Sloan Digital Sky Survey.

  17. The role of energy density.

    PubMed

    Drewnowski, Adam

    2003-02-01

    Dietary energy density (ED) appears to have a major influence on the regulation of food intake and body weight. If people consume a fixed weight of food each day, then high-ED diets should be associated with high energy intakes and with overweight. In contrast, low-ED diets should result in lower daily energy intakes and therefore weight loss. For this approach to work, low-ED foods must be as palatable as high-ED foods and, calorie for calorie, have a greater satiating power. Each of those assumptions is debatable. Dietary ED depends chiefly on the water content of foods. As a rule, high-ED foods are more palatable but less satiating, whereas low-ED foods are more satiating but less palatable. Consumer preferences for high-ED foods can be explained in terms of good taste, low cost, and convenience. Low-ED foods, such as fresh produce, provide less energy per unit cost than do high-ED foods, which often contain added sugars and fats. Poverty and obesity may well be linked through the habitual consumption of a low-cost, high-ED diet. PMID:12733741

  18. Bone Density in Cerebral Palsy

    PubMed Central

    Houlihan, Christine Murray; Stevenson, Richard D.

    2010-01-01

    Osteoporosis is a skeletal disorder characterized by compromised bone strength predisposing a person to an increased risk of fracture.1 Osteoporosis remains a major health problem worldwide, costing an estimated $13.8 billion in health care each year in the United States. Despite advances in treating osteoporosis in the elderly, no cure exists. Osteoporosis has its roots in childhood. Accrual of bone mass occurs throughout childhood and early adulthood, and peak bone mass is a key determinant of the lifetime risk of osteoporosis. Because the foundation for skeletal health is established so early in life, osteoporosis prevention begins by optimizing gains in bone mineral throughout childhood and adolescence.2,3 Osteoporosis evaluation and prevention is relevant to children with cerebral palsy (CP). CP is the most prevalent childhood condition associated with osteoporosis. Bone density is significantly decreased, and children with CP often sustain painful fractures with minimal trauma that impair their function and quality of life. Preventing or improving osteoporosis and maximizing bone accrual during critical stages of growth will minimize the future lifelong risks of fractures in children with CP. This article addresses the anatomy and structure of bone and bone metabolism, the clinical assessment of bone mass, the causes of osteoporosis and its evaluation and treatment in children with CP. PMID:19643349

  19. ]: a density functional theory investigation

    NASA Astrophysics Data System (ADS)

    Ulian, Gianfranco; Tosoni, Sergio; Valdrè, Giovanni

    2014-09-01

    In this work, we modelled the structure, the compressional behaviour and the physical properties of talc over a wide range of pressure using a quantum mechanical approach based on periodic boundary conditions. We adopted the density functional theory using the B3LYP-D* functional, which includes a correction for the dispersive forces and all-electron Gaussian-type orbitals basis sets. An atomic level description of the athermal pressure-induced structural modification of talc is provided. From the compression results, we obtained the athermal ( T = 0 K) bulk modulus ( K T0), its first derivative ( K') and the athermal volume at zero pressure ( V 0) by a third-order Birch-Murnaghan equation with parameters K T0 = 56.25 GPa, K' = 5.66 and V 0 = 450.34 Å3. The mechanical behaviour is highly anisotropic, as observed by the axial compressibility. The presented data are in very good agreement with recent experimental results obtained by single-crystal neutron and X-ray diffraction experiments.

  20. Hyperon matter at low densities

    SciTech Connect

    Sulaksono, A.

    2014-09-25

    It was reported recently that hyperons can be present inside PSRJ1614-2230 compact star. This can be realized only if the strength of the ω-hyperons and φ-hyperons coupling of conventional hyperons coupling constant on the extended relativistic mean field (ERMF) model increase by a factor of 1.5 to 3. In the present work, the mass and radius relation of the neutron star that is calculated by using BSR28 parameter set of ERMF model augmented with maximal coupling strength of the ω-hyperons and φ-hyperons (X=1), is compared to the mass and radius relation of the neutron star that is predicted by the same RMF parameter set but by assuming that hyperons do not exist in the matter (No. Hyp) as well as those by assuming the hyperons coupling constant fulfilled the conventional SU(6) and SU(3) symmetry. The consequences of implementing X=1 prescription are also discussed. The potential depths of hyperons in symmetric nuclear matter (SNM), pure neutron matter (PNM) and pure lambda matter (PLM) based on this parameter set are also calculated by using the X=1, SU (6) and SU (3) prescriptions. The results are compared to those obtained from microscopic models, quark meson coupling model (χ QMM) and the QCD sum rule for finite density (QCD SM) result.