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Sample records for energy loss spectroscopy

  1. Image simulation for electron energy loss spectroscopy

    SciTech Connect

    Oxley, Mark P.; Pennycook, Stephen J.

    2007-10-22

    In this paper, aberration correction of the probe forming optics of the scanning transmission electron microscope has allowed the probe-forming aperture to be increased in size, resulting in probes of the order of 1 Å in diameter. The next generation of correctors promise even smaller probes. Improved spectrometer optics also offers the possibility of larger electron energy loss spectrometry detectors. The localization of images based on core-loss electron energy loss spectroscopy is examined as function of both probe-forming aperture and detector size. The effective ionization is nonlocal in nature, and two common local approximations are compared to full nonlocal calculations. Finally, the affect of the channelling of the electron probe within the sample is also discussed.

  2. Image simulation for electron energy loss spectroscopy

    DOE PAGESBeta

    Oxley, Mark P.; Pennycook, Stephen J.

    2007-10-22

    In this paper, aberration correction of the probe forming optics of the scanning transmission electron microscope has allowed the probe-forming aperture to be increased in size, resulting in probes of the order of 1 Å in diameter. The next generation of correctors promise even smaller probes. Improved spectrometer optics also offers the possibility of larger electron energy loss spectrometry detectors. The localization of images based on core-loss electron energy loss spectroscopy is examined as function of both probe-forming aperture and detector size. The effective ionization is nonlocal in nature, and two common local approximations are compared to full nonlocal calculations.more » Finally, the affect of the channelling of the electron probe within the sample is also discussed.« less

  3. Electron energy loss spectroscopy in advanced materials

    SciTech Connect

    Zaluzec, N.J.

    1991-01-01

    The combination of a Transmission Electron Microscope (TEM) with an electron energy loss spectrometer (EELS) yields a powerful tool for the microcharacterization of materials. However, the application of this technique to advanced materials problems can only be fully appreciated when the information obtained using EELS is related to that obtained from other analytical spectroscopies. In this chapter, we briefly discuss the relative performance of X-ray, Auger and Photoelectron Spectroscopies with EELS pointing out the limitations and merits of each. This comparison is followed by examples of the application of EELS to investigations involving high {Tc} superconductors, artificial metallic superlattices, amorphous magnetic materials and the characterization of metallic hydride phases. 14 refs., 22 figs.

  4. Electron energy loss spectroscopy of disilane

    SciTech Connect

    Dillon, M.A.; Spence, D.; Boesten, L.; Tanaka, H.

    1988-04-01

    Electron energy loss spectra of disilane have been recorded over an excitation energy range of 20 eV employing electrons of 20 and 200 eV incident energy for scattering angles of 0/sup 0/--90/sup 0/. Every transition detected except one appears at an energy consistent with the first observed members of Rydberg series converging to one of four possible ion states. The first two observed transitions belong to (2a/sub 1//sub g/)/sup 2/..-->../sup 1//sup ,//sup 3/(2a/sub 1//sub g/,4s) dipole forbidden channels appearing at excitation energies of )similarreverse arrowto)6.3 and 7.05 eV for the triplet and singlet, respectively. Evidence is presented for the identification of additional forbidden transitions as well as possible low-lying valence transition

  5. Angle resolved electron energy loss spectroscopy on graphite

    NASA Astrophysics Data System (ADS)

    Diebold, U.; Preisinger, A.; Schattschneider, P.; Varga, P.

    We report on angle resolved electron energy loss spectroscopy (EELS) in reflection mode with low primary energy on a graphite single crystal. Measurements with primary electron energy of 175 eV have been performed in off-Bragg-reflex geometry in two different directions within the (0001) surface plane of the graphite single crystal. In addition, EELS measurements in specular reflection mode with different primary energies and angles of incidence were done in order to distinguish between surface and bulk plasmon losses. The energy losses and the transferred momenta of the losses have been analyzed. The results are compared with the loss functions for bulk and surface excitations calculated from the dielectric function ɛ(ω, q) obtained from TEELS-data (EELS in transmission mode) [Springer Tracts Mod. Phys. 54 (1970) 77].

  6. Tomographic study of ion tracks by ion energy loss spectroscopy

    SciTech Connect

    Vacik, J.; Havranek, V.; Hnatowicz, V.; Lavrentiev, V.; Horak, P.; Fink, D.; Apel, P.

    2013-04-19

    Ion energy loss spectroscopy is suggested to determine the shape of the (latent, etched and filled) ion tracks in polymers using ion probes of various beam sizes. For a milli-probe, it can be considered as a one-dimensional tomography of many identical (rotationally symmetric) objects. For a micro-probe, the technique can be understood as a micro-tomography of the single ion track. In both cases, the ion energy loss spectroscopy requires monoenergetic ions with a low intensity (< 10{sup -3} s{sup -1}) and a well defined angular beam set-up. Here we present a study of the possible use of the ion milli-and micro-probes in a tomographic study of the ion track 3D geometry and its evolution during chemical etching.

  7. Probing battery chemistry with liquid cell electron energy loss spectroscopy

    DOE PAGESBeta

    Unocic, Raymond R.; Baggetto, Loic; Veith, Gabriel M.; Unocic, Kinga A.; Sacci, Robert L.; Dudney, Nancy J.; More, Karren Leslie; Aguiar, Jeffery A.

    2015-09-15

    Electron energy loss spectroscopy (EELS) was used to determine the chemistry and oxidation state of LiMn2O4 and Li4Ti5O12 thin film battery electrodes in liquid cells for in situ scanning/transmission electron microscopy (S/TEM). Using the L2,3 white line intensity ratio method we determine the oxidation state of Mn and Ti in a liquid electrolyte solvent and discuss experimental parameters that influence measurement sensitivity.

  8. Electron Energy Loss Spectroscopy of a Chiral Plasmonic Structure

    NASA Astrophysics Data System (ADS)

    Paterson, G. W.; Karimullah, A.; Williamson, SDR; Kadodwala, M.; MacLaren, D. A.

    2015-10-01

    A detailed analysis of the plasmonic excitations within a nanopatterned gold chiral biosensor element, measured by scanning transmission electron microscopy electron energy loss spectroscopy, is presented. We discuss aspects of data acquisition, processing, analysis and simulation. The localised surface plasmonic resonance modes in the structure are extracted using non-negative matrix factorisation and we use simulations to correlate notable deviations from the idealised spectrum to nanometric fabrication imperfections. The methodology presented has wide applicability to a variety of metamaterials.

  9. Diamond /111/ studied by electron energy loss spectroscopy in the characteristic loss region

    NASA Technical Reports Server (NTRS)

    Pepper, S. V.

    1982-01-01

    Unoccupied surface states on diamond (111) annealed at greater than 900 C are studied by electron energy loss spectroscopy with valence band excitation. A feature found at 2.1 eV loss energy is attributed to an excitation from occupied surface states into unoccupied surface states of energy within the bulk band gap. A surface band gap of approximately 1 eV is estimated. This result supports a previous suggestion for unoccupied band gap states based on core level energy loss spectroscopy. Using the valence band excitation energy loss spectrosocpy, it is also suggested that hydrogen is removed from the as-polished diamond surface by a Menzel-Gomer-Redhead mechanism.

  10. Tomography of Particle Plasmon Fields from Electron Energy Loss Spectroscopy

    NASA Astrophysics Data System (ADS)

    Hörl, Anton; Trügler, Andreas; Hohenester, Ulrich

    2013-08-01

    We theoretically investigate electron energy loss spectroscopy (EELS) of metallic nanoparticles in the optical frequency domain. Using a quasistatic approximation scheme together with a plasmon eigenmode expansion, we show that EELS can be rephrased in terms of a tomography problem. For selected single and coupled nanoparticles we extract the three-dimensional plasmon fields from a collection of rotated EELS maps. Our results pave the way for a fully three-dimensional plasmon-field tomography and establish EELS as a quantitative measurement device for plasmonics.

  11. Simulating electron energy loss spectroscopy with the MNPBEM toolbox

    NASA Astrophysics Data System (ADS)

    Hohenester, Ulrich

    2014-03-01

    Within the MNPBEM toolbox, we show how to simulate electron energy loss spectroscopy (EELS) of plasmonic nanoparticles using a boundary element method approach. The methodology underlying our approach closely follows the concepts developed by García de Abajo and coworkers (Garcia de Abajo, 2010). We introduce two classes eelsret and eelsstat that allow in combination with our recently developed MNPBEM toolbox for a simple, robust, and efficient computation of EEL spectra and maps. The classes are accompanied by a number of demo programs for EELS simulation of metallic nanospheres, nanodisks, and nanotriangles, and for electron trajectories passing by or penetrating through the metallic nanoparticles. We also discuss how to compute electric fields induced by the electron beam and cathodoluminescence. Catalogue identifier: AEKJ_v2_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEKJ_v2_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.: 38886 No. of bytes in distributed program, including test data, etc.: 1222650 Distribution format: tar.gz Programming language: Matlab 7.11.0 (R2010b). Computer: Any which supports Matlab 7.11.0 (R2010b). Operating system: Any which supports Matlab 7.11.0 (R2010b). RAM:≥1 GB Classification: 18. Catalogue identifier of previous version: AEKJ_v1_0 Journal reference of previous version: Comput. Phys. Comm. 183 (2012) 370 External routines: MESH2D available at www.mathworks.com Does the new version supersede the previous version?: Yes Nature of problem: Simulation of electron energy loss spectroscopy (EELS) for plasmonic nanoparticles. Solution method: Boundary element method using electromagnetic potentials. Reasons for new version: The new version of the toolbox includes two additional classes for the simulation of electron energy

  12. Probing battery chemistry with liquid cell electron energy loss spectroscopy.

    PubMed

    Unocic, Raymond R; Baggetto, Loïc; Veith, Gabriel M; Aguiar, Jeffery A; Unocic, Kinga A; Sacci, Robert L; Dudney, Nancy J; More, Karren L

    2015-11-25

    We demonstrate the ability to apply electron energy loss spectroscopy (EELS) to follow the chemistry and oxidation states of LiMn2O4 and Li4Ti5O12 battery electrodes within a battery solvent. This is significant as the use and importance of in situ electrochemical cells coupled with a scanning/transmission electron microscope (S/TEM) has expanded and been applied to follow changes in battery chemistry during electrochemical cycling. We discuss experimental parameters that influence measurement sensitivity and provide a framework to apply this important analytical method to future in situ electrochemical studies. PMID:26404766

  13. Probing battery chemistry with liquid cell electron energy loss spectroscopy

    SciTech Connect

    Unocic, Raymond R.; Baggetto, Loic; Veith, Gabriel M.; Unocic, Kinga A.; Sacci, Robert L.; Dudney, Nancy J.; More, Karren Leslie; Aguiar, Jeffery A.

    2015-09-15

    Electron energy loss spectroscopy (EELS) was used to determine the chemistry and oxidation state of LiMn2O4 and Li4Ti5O12 thin film battery electrodes in liquid cells for in situ scanning/transmission electron microscopy (S/TEM). Using the L2,3 white line intensity ratio method we determine the oxidation state of Mn and Ti in a liquid electrolyte solvent and discuss experimental parameters that influence measurement sensitivity.

  14. Probing Battery Chemistry with Liquid Cell Electron Energy Loss Spectroscopy

    SciTech Connect

    Unocic, Raymond R.; Baggetto, Loic; Veith, Gabriel M.; Aguiar, Jeffery A.; Unocic, Kinga A.; Sacci, Robert L.; Dudney, Nancy J.; More, Karren L.

    2015-11-25

    We demonstrate the ability to apply electron energy loss spectroscopy (EELS) to follow the chemistry and oxidation states of LiMn2O4 and Li4Ti5O12 battery electrodes within a battery solvent. The use and importance of in situ electrochemical cells coupled with a scanning/transmission electron microscope (S/TEM) has expanded and been applied to follow changes in battery chemistry during electrochemical cycling. Furthermore, we discuss experimental parameters that influence measurement sensitivity and provide a framework to apply this important analytical method to future in situ electrochemical studies.

  15. Development of electron energy-loss spectroscopy for nanoscience.

    PubMed

    Yuan, Jun; Wang, Zhiwei; Fu, Xin; Xie, Lin; Sun, Yuekui; Gao, Shangpeng; Jiang, Jun; Hu, Xuerang; Xu, Chen

    2008-08-01

    Electron energy-loss spectroscopy (EELS) has been well established in providing the composition and chemical bonding information of materials, particularly for light elements. Its potential for structural determination has long been known but has yet to be fully explored. With the convergence of rapid development in computing power and improvement in the efficiency of the material specific electronic structure simulation, plus the recent breakthrough in the development of C(s)-corrected electron microscopy, the reconstruction of the local three dimensional structure of nanomaterial using EELS in conjunction with advanced structural imaging and diffraction techniques is becoming increasingly feasible. In this paper, we will review from our own examples the progress in EELS instrumentation, methods and simulation to illustrate the progress that has been made. They include the density-function-theory-based ab initio spectroscopic simulation for standard-less fingerprint applications for metastable polymorph identification, magic angle electron energy-loss spectroscopy as well as recent results from the dual-detectors EELS system which allows the energy instability of the spectrometer to be analyzed in real-time and eventually compensated on-line. PMID:18166483

  16. Electron energy loss spectroscopy of gold nanoparticles on graphene

    SciTech Connect

    DeJarnette, Drew; Roper, D. Keith

    2014-08-07

    Plasmon excitation decay by absorption, scattering, and hot electron transfer has been distinguished from effects induced by incident photons for gold nanoparticles on graphene monolayer using electron energy loss spectroscopy (EELS). Gold nano-ellipses were evaporated onto lithographed graphene, which was transferred onto a silicon nitride transmission electron microscopy grid. Plasmon decay from lithographed nanoparticles measured with EELS was compared in the absence and presence of the graphene monolayer. Measured decay values compared favorably with estimated radiative and non-radiative contributions to decay in the absence of graphene. Graphene significantly enhanced low-energy plasmon decay, increasing mode width 38%, but did not affect higher energy plasmon or dark mode decay. This decay beyond expected radiative and non-radiative mechanisms was attributed to hot electron transfer, and had quantum efficiency of 20%, consistent with previous reports.

  17. In situ electron energy-loss spectroscopy in liquids.

    PubMed

    Holtz, Megan E; Yu, Yingchao; Gao, Jie; Abruña, Héctor D; Muller, David A

    2013-08-01

    In situ scanning transmission electron microscopy (STEM) through liquids is a promising approach for exploring biological and materials processes. However, options for in situ chemical identification are limited: X-ray analysis is precluded because the liquid cell holder shadows the detector and electron energy-loss spectroscopy (EELS) is degraded by multiple scattering events in thick layers. Here, we explore the limits of EELS in the study of chemical reactions in their native environments in real time and on the nanometer scale. The determination of the local electron density, optical gap, and thickness of the liquid layer by valence EELS is demonstrated. By comparing theoretical and experimental plasmon energies, we find that liquids appear to follow the free-electron model that has been previously established for solids. Signals at energies below the optical gap and plasmon energy of the liquid provide a high signal-to-background ratio regime as demonstrated for LiFePO4 in an aqueous solution. The potential for the use of valence EELS to understand in situ STEM reactions is demonstrated for beam-induced deposition of metallic copper: as copper clusters grow, EELS develops low-loss peaks corresponding to metallic copper. From these techniques, in situ imaging and valence EELS offer insights into the local electronic structure of nanoparticles and chemical reactions. PMID:23721691

  18. Characterizing Localized Surface Plasmons Using Electron Energy-Loss Spectroscopy

    NASA Astrophysics Data System (ADS)

    Cherqui, Charles; Thakkar, Niket; Li, Guoliang; Camden, Jon P.; Masiello, David J.

    2016-05-01

    Electron energy-loss spectroscopy (EELS) offers a window to view nanoscale properties and processes. When performed in a scanning transmission electron microscope, EELS can simultaneously render images of nanoscale objects with subnanometer spatial resolution and correlate them with spectroscopic information at a spectral resolution of ˜10-100 meV. Consequently, EELS is a near-perfect tool for understanding the optical and electronic properties of individual plasmonic metal nanoparticles and few-nanoparticle assemblies, which are significant in a wide range of fields. This review presents an overview of basic plasmonics and EELS theory and highlights several recent noteworthy experiments involving the interrogation of plasmonic metal nanoparticle systems using electron beams.

  19. Modeling ellipsometry and electron energy loss spectroscopy of graphene

    SciTech Connect

    Lyon, Keenan A.; Miskovic, Zoran L.; Diebold, Alain C.; Idrobo, Juan-Carlos

    2014-03-31

    Recent studies of electronic excitations in graphene by Electron Energy Loss Spectroscopy (EELS) have revealed massive high-frequency peaks assigned to the π and σ+π plasmons [1], which were semi-quantitatively modeled with a two-dimensional, two-fluid hydrodynamic (HD) model [2]. On the other hand, Spectroscopic Ellipsometry (SE) of graphene covers the region of nearly constant absorbance due to graphene’s universal optical conductivity at infrared frequencies, which is not clearly resolved by EELS, and goes up to cover the π-plasmon peak at ultraviolet frequencies [3]. To attempt to model both the SE and EELS, we amend the HD model by including a low-frequency contribution of graphene’s inter-band transitions, while monitoring the fulfillment of the f-sum rule [4] up to frequencies that cover excitations of all valence electrons.

  20. Data processing for atomic resolution electron energy loss spectroscopy.

    PubMed

    Cueva, Paul; Hovden, Robert; Mundy, Julia A; Xin, Huolin L; Muller, David A

    2012-08-01

    The high beam current and subangstrom resolution of aberration-corrected scanning transmission electron microscopes has enabled electron energy loss spectroscopy (EELS) mapping with atomic resolution. These spectral maps are often dose limited and spatially oversampled, leading to low counts/channel and are thus highly sensitive to errors in background estimation. However, by taking advantage of redundancy in the dataset map, one can improve background estimation and increase chemical sensitivity. We consider two such approaches--linear combination of power laws and local background averaging--that reduce background error and improve signal extraction. Principal component analysis (PCA) can also be used to analyze spectrum images, but the poor peak-to-background ratio in EELS can lead to serious artifacts if raw EELS data are PCA filtered. We identify common artifacts and discuss alternative approaches. These algorithms are implemented within the Cornell Spectrum Imager, an open source software package for spectroscopic analysis. PMID:22697429

  1. Single-atom electron energy loss spectroscopy of light elements

    PubMed Central

    Senga, Ryosuke; Suenaga, Kazu

    2015-01-01

    Light elements such as alkali metal (lithium, sodium) or halogen (fluorine, chlorine) are present in various substances and indeed play significant roles in our life. Although atomic behaviours of these elements are often a key to resolve chemical or biological activities, they are hardly visible in transmission electron microscope because of their smaller scattering power and higher knock-on probability. Here we propose a concept for detecting light atoms encaged in a nanospace by means of electron energy loss spectroscopy using inelastically scattered electrons. In this method, we demonstrate the single-atom detection of lithium, fluorine, sodium and chlorine with near-atomic precision, which is limited by the incident probe size, signal delocalization and atomic movement in nanospace. Moreover, chemical shifts of lithium K-edge have been successfully identified with various atomic configurations in one-dimensional lithium compounds. PMID:26228378

  2. Uranium trioxide behavior during electron energy loss spectroscopy analysis

    NASA Astrophysics Data System (ADS)

    Degueldre, Claude; Alekseev, Evgeny V.

    2015-03-01

    A sample of uranium trioxide (UO3) was produced by focused ion beam (~10 μm×~10 μm×<0.5 μm) for transmission electron and electron energy loss (EEL) spectroscopy examinations in a transmission electron microscope (TEM). The EEL spectra were recorded as a function of the thickness for the P and O edges in the low energy range 0-350 eV and were compared to spectra of UO3 small grains attached to a TEM grid. The EEL spectrum was studied through a range of thicknesses going from ~60 to ~260 nm. The EEL spectra recorded for UO3 are compared with those recorded for UO2. The reduction of UO3 into U4O9 and/or UO2 is readily observed apparently during the TEM investigations and as confirmed by electron diffraction (eD). This redox effect is similar to that known for other redox sensitive oxides. Recommendations are suggested to avoid sample decomposition.

  3. Low-loss electron energy loss spectroscopy: An atomic-resolution complement to optical spectroscopies and application to graphene

    DOE PAGESBeta

    Kapetanakis, Myron; Zhou, Wu; Oxley, Mark P.; Lee, Jaekwang; Prange, Micah P.; Pennycook, Stephen J.; Idrobo Tapia, Juan Carlos; Pantelides, Sokrates T.

    2015-09-25

    Photon-based spectroscopies have played a central role in exploring the electronic properties of crystalline solids and thin films. They are a powerful tool for probing the electronic properties of nanostructures, but they are limited by lack of spatial resolution. On the other hand, electron-based spectroscopies, e.g., electron energy loss spectroscopy (EELS), are now capable of subangstrom spatial resolution. Core-loss EELS, a spatially resolved analog of x-ray absorption, has been used extensively in the study of inhomogeneous complex systems. In this paper, we demonstrate that low-loss EELS in an aberration-corrected scanning transmission electron microscope, which probes low-energy excitations, combined with amore » theoretical framework for simulating and analyzing the spectra, is a powerful tool to probe low-energy electron excitations with atomic-scale resolution. The theoretical component of the method combines density functional theory–based calculations of the excitations with dynamical scattering theory for the electron beam. We apply the method to monolayer graphene in order to demonstrate that atomic-scale contrast is inherent in low-loss EELS even in a perfectly periodic structure. The method is a complement to optical spectroscopy as it probes transitions entailing momentum transfer. The theoretical analysis identifies the spatial and orbital origins of excitations, holding the promise of ultimately becoming a powerful probe of the structure and electronic properties of individual point and extended defects in both crystals and inhomogeneous complex nanostructures. The method can be extended to probe magnetic and vibrational properties with atomic resolution.« less

  4. Low-loss electron energy loss spectroscopy: An atomic-resolution complement to optical spectroscopies and application to graphene

    SciTech Connect

    Kapetanakis, Myron; Zhou, Wu; Oxley, Mark P.; Lee, Jaekwang; Prange, Micah P.; Pennycook, Stephen J.; Idrobo Tapia, Juan Carlos; Pantelides, Sokrates T.

    2015-09-25

    Photon-based spectroscopies have played a central role in exploring the electronic properties of crystalline solids and thin films. They are a powerful tool for probing the electronic properties of nanostructures, but they are limited by lack of spatial resolution. On the other hand, electron-based spectroscopies, e.g., electron energy loss spectroscopy (EELS), are now capable of subangstrom spatial resolution. Core-loss EELS, a spatially resolved analog of x-ray absorption, has been used extensively in the study of inhomogeneous complex systems. In this paper, we demonstrate that low-loss EELS in an aberration-corrected scanning transmission electron microscope, which probes low-energy excitations, combined with a theoretical framework for simulating and analyzing the spectra, is a powerful tool to probe low-energy electron excitations with atomic-scale resolution. The theoretical component of the method combines density functional theory–based calculations of the excitations with dynamical scattering theory for the electron beam. We apply the method to monolayer graphene in order to demonstrate that atomic-scale contrast is inherent in low-loss EELS even in a perfectly periodic structure. The method is a complement to optical spectroscopy as it probes transitions entailing momentum transfer. The theoretical analysis identifies the spatial and orbital origins of excitations, holding the promise of ultimately becoming a powerful probe of the structure and electronic properties of individual point and extended defects in both crystals and inhomogeneous complex nanostructures. The method can be extended to probe magnetic and vibrational properties with atomic resolution.

  5. Low-energy excitations in Cu-O--based superconductors with electron-energy-loss spectroscopy

    SciTech Connect

    Kelly, M.K. ); Meng, Y. ); Hwu, Y.; Chang, Y. ); Chen, Y.; Lapeyre, G.J. ); Margaritondo, G. )

    1989-12-01

    We have investigated the ability of high-resolution electron-energy-loss spectroscopy to contribute to the understanding of the Cu-O superconductors. Our results do not show temperature dependence attributable to the superconducting transition, perhaps in part due to high surface sensitivity. A strong loss feature at 50 meV appears to be due to phonon modes, involving oxygen in the Cu-O planes, that have a strong dipole moment.

  6. High resolution electron energy loss spectroscopy with two-dimensional energy and momentum mapping.

    PubMed

    Zhu, Xuetao; Cao, Yanwei; Zhang, Shuyuan; Jia, Xun; Guo, Qinlin; Yang, Fang; Zhu, Linfan; Zhang, Jiandi; Plummer, E W; Guo, Jiandong

    2015-08-01

    High resolution electron energy loss spectroscopy (HREELS) is a powerful technique to probe vibrational and electronic excitations at surfaces. The dispersion relation of surface excitations, i.e., energy as a function of momentum, has in the past, been obtained by measuring the energy loss at a fixed angle (momentum) and then rotating sample, monochromator, or analyzer. Here, we introduce a new strategy for HREELS, utilizing a specially designed lens system with a double-cylindrical Ibach-type monochromator combined with a commercial VG Scienta hemispherical electron energy analyzer, which can simultaneously measure the energy and momentum of the scattered electrons. The new system possesses high angular resolution (<0.1°), detecting efficiency and sampling density. The capabilities of this system are demonstrated using Bi2Sr2CaCu2O(8+δ). The time required to obtain a complete dispersion spectrum is at least one order of magnitude shorter than conventional spectrometers, with improved momentum resolution and no loss in energy resolution. PMID:26329206

  7. High resolution electron energy loss spectroscopy with two-dimensional energy and momentum mapping

    SciTech Connect

    Zhu, Xuetao; Cao, Yanwei; Zhang, Shuyuan; Jia, Xun; Guo, Qinlin; Yang, Fang; Zhu, Linfan; Zhang, Jiandi; Plummer, E. W.; Guo, Jiandong

    2015-08-15

    High resolution electron energy loss spectroscopy (HREELS) is a powerful technique to probe vibrational and electronic excitations at surfaces. The dispersion relation of surface excitations, i.e., energy as a function of momentum, has in the past, been obtained by measuring the energy loss at a fixed angle (momentum) and then rotating sample, monochromator, or analyzer. Here, we introduce a new strategy for HREELS, utilizing a specially designed lens system with a double-cylindrical Ibach-type monochromator combined with a commercial VG Scienta hemispherical electron energy analyzer, which can simultaneously measure the energy and momentum of the scattered electrons. The new system possesses high angular resolution (<0.1°), detecting efficiency and sampling density. The capabilities of this system are demonstrated using Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8+δ}. The time required to obtain a complete dispersion spectrum is at least one order of magnitude shorter than conventional spectrometers, with improved momentum resolution and no loss in energy resolution.

  8. Depth-selective X-ray absorption spectroscopy by detection of energy-loss Auger electrons

    NASA Astrophysics Data System (ADS)

    Isomura, Noritake; Soejima, Narumasa; Iwasaki, Shiro; Nomoto, Toyokazu; Murai, Takaaki; Kimoto, Yasuji

    2015-11-01

    A unique X-ray absorption spectroscopy (XAS) method is proposed for depth profiling of chemical states in material surfaces. Partial electron yield mode detecting energy-loss Auger electrons, called the inelastic electron yield (IEY) mode, enables a variation in the probe depth. As an example, Si K-edge XAS spectra for a well-defined multilayer sample (Si3N4/SiO2/Si) have been investigated using this method at various kinetic energies. We found that the peaks assigned to the layers from the top layer to the substrate appeared in the spectra in the order of increasing energy loss relative to the Auger electrons. Thus, the probe depth can be changed by the selection of the kinetic energy of the energy loss electrons in IEY-XAS.

  9. Toward 10 meV electron energy-loss spectroscopy resolution for plasmonics.

    PubMed

    Bellido, Edson P; Rossouw, David; Botton, Gianluigi A

    2014-06-01

    Energy resolution is one of the most important parameters in electron energy-loss spectroscopy. This is especially true for measurement of surface plasmon resonances, where high-energy resolution is crucial for resolving individual resonance peaks, in particular close to the zero-loss peak. In this work, we improve the energy resolution of electron energy-loss spectra of surface plasmon resonances, acquired with a monochromated beam in a scanning transmission electron microscope, by the use of the Richardson-Lucy deconvolution algorithm. We test the performance of the algorithm in a simulated spectrum and then apply it to experimental energy-loss spectra of a lithographically patterned silver nanorod. By reduction of the point spread function of the spectrum, we are able to identify low-energy surface plasmon peaks in spectra, more localized features, and higher contrast in surface plasmon energy-filtered maps. Thanks to the combination of a monochromated beam and the Richardson-Lucy algorithm, we improve the effective resolution down to 30 meV, and evidence of success up to 10 meV resolution for losses below 1 eV. We also propose, implement, and test two methods to limit the number of iterations in the algorithm. The first method is based on noise measurement and analysis, while in the second we monitor the change of slope in the deconvolved spectrum. PMID:24690472

  10. Experimental and theoretical determination of the low-loss electron energy loss spectroscopy of nanostructured ZnO.

    PubMed

    Morales-Rodríguez, H J; Espinosa-Magaña, F

    2012-02-01

    The dielectric properties of nanostructured wurtzite-type ZnO are studied by analyzing the low-loss region of the electron energy loss spectroscopy (EELS) in a transmission electron microscope. Characteristic peaks at about 12 and 32 eV in the imaginary part of the dielectric function shift to lower energies as particle size decreases. A comparison of experimental EELS spectra and ab initio density-functional theory calculations (WIEN2k code) within the generalized gradient approximation (GGA), GGA+U and modified Becke-Johnson (mBJ) is presented. The origins of interband transitions are identified in the electronic band structure by calculating the partial imaginary part of the dielectric function and the partial density of states of Zn and O. PMID:21813282

  11. Precessed electron beam electron energy loss spectroscopy of graphene: Beyond channelling effects

    SciTech Connect

    Yedra, Ll.; Estradé, S.; Torruella, P.; Eljarrat, A.; Peiró, F.; Darbal, A. D.; Weiss, J. K.

    2014-08-04

    The effects of beam precession on the Electron Energy Loss Spectroscopy (EELS) signal of the carbon K edge in a 2 monolayer graphene sheet are studied. In a previous work, we demonstrated the use of precession to compensate for the channeling-induced reduction of EELS signal when in zone axis. In the case of graphene, no enhancement of EELS signal is found in the usual experimental conditions, as graphene is not thick enough to present channeling effects. Interestingly, though it is found that precession makes it possible to increase the collection angle, and, thus, the overall signal, without a loss of signal-to-background ratio.

  12. Electron Energy-Loss Spectroscopy: Fundamentals and applications in the characterization of minerals

    SciTech Connect

    Krishnan, K.M.

    1989-04-01

    The combined use of an energy-loss spectrometer and an analytical electron microscope with fine probe forming capabilities provides a wealth of information about the sample at high spatial resolution. Fundamental principles governing the physics of the interaction between the fast electron and a thin foil sample, to account for the fine structure in the inelastically scattered fast electron distribution (Electron-Energy Loss Spectroscopy, EELS), will be reviewed. General application of EELS is in the area of low atomic number elements (Z < 11) microanalysis, where it significantly complements the more widely used Energy Dispersive X-ray Spectroscopy (EDXS). However, a careful analysis of the low loss plasmon oscillations and the fine structure in the core-loss edges, can provide additional information related to the bonding and electronic structure of the sample. An illustration of this is presented from our study of Cdelta diamond residue from the Allende carbonaceous chondrite. Combination of EELS with channeling effects can provide specific site occupation/valence information in crystalline materials. Details of this novel crystallographic method will be outlined and illustrated with an example of the study of chromite spinels. Finally, some pertinent experimental details will be discussed. 7 figs.

  13. Oxygen diffusion from anodic surface oxide films on titanium subhydride studies by auger electron spectroscopy and electron energy loss spectroscopy

    NASA Astrophysics Data System (ADS)

    Wang, P. S.; Wittberg, T. N.; Wolf, J. D.; Keil, R. G.

    TiH sub x (0.5 less than x less than 1.7) samples were prepared from titanium foil in order to study the diffusion of oxygen in the titanium subhydride. An anodic oxide, 1000A thick, was grown on the titanium subhydride foils in an agueous saturated solution of ammonium tetraborate. These anodized samples were then heat treated at temperatures between 500 and 600(0)C and changes in the profile of oxygen concentration as a function of depth were monitored using auger electron spectroscopy. From this data then it was possible to calculate the diffusivity of oxygen in the titanium subhydride. It was also found that electron energy loss spectroscopy could be used to determine the titanium subhydride stoichiometry in the near-surface region. This was done by measuring the energy of the bulk plasmon loss peak, which for TiH sub x, varies linearly with hydrogen content. The amount of dehydriding which occurred following a given heat treatment could be determined from profiles of the plasmon loss energy as a function of depth. A sample of anodized TiH0 87 was studied in some detail. Significant dehydriding of this sample for heat treatment times of less than one hour only occured at temperatures above 550(0)C.

  14. Energy-loss- and thickness-dependent contrast in atomic-scale electron energy-loss spectroscopy

    SciTech Connect

    Tan, Haiyan; Zhu, Ye; Dwyer, Christian; Xin, Huolin L.

    2014-12-31

    Atomic-scale elemental maps of materials acquired by core-loss inelastic electron scattering often exhibit an undesirable sensitivity to the unavoidable elastic scattering, making the maps counter-intuitive to interpret. Here, we present a systematic study that scrutinizes the energy-loss and sample-thickness dependence of atomic-scale elemental maps acquired using 100 keV incident electrons in a scanning transmission electron microscope. For single-crystal silicon, the balance between elastic and inelastic scattering means that maps generated from the near-threshold Si-L signal (energy loss of 99 eV) show no discernible contrast for a thickness of 0.5λ (λ is the electron mean-free path, here approximately 110 nm). At greater thicknesses we observe a counter-intuitive “negative” contrast. Only at much higher energy losses is an intuitive “positive” contrast gradually restored. Our quantitative analysis shows that the energy-loss at which a positive contrast is restored depends linearly on the sample thickness. This behavior is in very good agreement with our double-channeling inelastic scattering calculations. We test a recently-proposed experimental method to correct the core-loss inelastic scattering and restore an intuitive “positive” chemical contrast. The method is demonstrated to be reliable over a large range of energy losses and sample thicknesses. The corrected contrast for near-threshold maps is demonstrated to be (desirably) inversely proportional to sample thickness. As a result, implications for the interpretation of atomic-scale elemental maps are discussed.

  15. Energy-loss- and thickness-dependent contrast in atomic-scale electron energy-loss spectroscopy

    DOE PAGESBeta

    Tan, Haiyan; Zhu, Ye; Dwyer, Christian; Xin, Huolin L.

    2014-12-31

    Atomic-scale elemental maps of materials acquired by core-loss inelastic electron scattering often exhibit an undesirable sensitivity to the unavoidable elastic scattering, making the maps counter-intuitive to interpret. Here, we present a systematic study that scrutinizes the energy-loss and sample-thickness dependence of atomic-scale elemental maps acquired using 100 keV incident electrons in a scanning transmission electron microscope. For single-crystal silicon, the balance between elastic and inelastic scattering means that maps generated from the near-threshold Si-L signal (energy loss of 99 eV) show no discernible contrast for a thickness of 0.5λ (λ is the electron mean-free path, here approximately 110 nm). Atmore » greater thicknesses we observe a counter-intuitive “negative” contrast. Only at much higher energy losses is an intuitive “positive” contrast gradually restored. Our quantitative analysis shows that the energy-loss at which a positive contrast is restored depends linearly on the sample thickness. This behavior is in very good agreement with our double-channeling inelastic scattering calculations. We test a recently-proposed experimental method to correct the core-loss inelastic scattering and restore an intuitive “positive” chemical contrast. The method is demonstrated to be reliable over a large range of energy losses and sample thicknesses. The corrected contrast for near-threshold maps is demonstrated to be (desirably) inversely proportional to sample thickness. As a result, implications for the interpretation of atomic-scale elemental maps are discussed.« less

  16. Communication: Investigation of the electron momentum density distribution of nanodiamonds by electron energy-loss spectroscopy.

    PubMed

    Feng, Zhenbao; Yang, Bing; Lin, Yangming; Su, Dangsheng

    2015-12-01

    The electron momentum distribution of detonation nanodiamonds (DND) was investigated by recording electron energy-loss spectra at large momentum transfer in the transmission electron microscope (TEM), which is known as electron Compton scattering from solid (ECOSS). Compton profile of diamond film obtained by ECOSS was found in good agreement with prior photon experimental measurement and theoretical calculation that for bulk diamond. Compared to the diamond film, the valence Compton profile of DND was found to be narrower, which indicates a more delocalization of the ground-state charge density for the latter. Combining with other TEM characterizations such as high-resolution transmission electron spectroscopy, diffraction, and energy dispersive X-ray spectroscopy measurements, ECOSS was shown to be a great potential technique to study ground-state electronic properties of nanomaterials. PMID:26646862

  17. Communication: Investigation of the electron momentum density distribution of nanodiamonds by electron energy-loss spectroscopy

    SciTech Connect

    Feng, Zhenbao; Yang, Bing; Lin, Yangming; Su, Dangsheng

    2015-12-07

    The electron momentum distribution of detonation nanodiamonds (DND) was investigated by recording electron energy-loss spectra at large momentum transfer in the transmission electron microscope (TEM), which is known as electron Compton scattering from solid (ECOSS). Compton profile of diamond film obtained by ECOSS was found in good agreement with prior photon experimental measurement and theoretical calculation that for bulk diamond. Compared to the diamond film, the valence Compton profile of DND was found to be narrower, which indicates a more delocalization of the ground-state charge density for the latter. Combining with other TEM characterizations such as high-resolution transmission electron spectroscopy, diffraction, and energy dispersive X-ray spectroscopy measurements, ECOSS was shown to be a great potential technique to study ground-state electronic properties of nanomaterials.

  18. Electron energy-loss spectroscopy study of thin film hafnium aluminates for novel gate dielectrics.

    PubMed

    Stemmer, S; Chen, Z Q; Zhu, W J; Ma, T P

    2003-04-01

    We have used conventional high-resolution transmission electron microscopy and electron energy-loss spectroscopy (EELS) in scanning transmission electron microscopy to investigate the microstructure and electronic structure of hafnia-based thin films doped with small amounts (6.8 at.%) of Al grown on (001) Si. The as-deposited film is amorphous with a very thin (approximately 0.5 nm) interfacial SiOx layer. The film partially crystallizes after annealing at 700 degrees C and the interfacial SiO2-like layer increases in thickness by oxygen diffusion through the Hf-aluminate layer and oxidation of the silicon substrate. Oxygen K-edge EELS fine-structures are analysed for both films and interpreted in the context of the films' microstructure. We also discuss valence electron energy-loss spectra of these ultrathin films. PMID:12694419

  19. Sensitivity of photoelectron energy loss spectroscopy to surface reconstruction of microcrystalline diamond films

    NASA Astrophysics Data System (ADS)

    David, Denis G. F.; Pinault-Thaury, Marie-Amandine; Ballutaud, Dominique; Godet, Christian

    2013-05-01

    In X-ray Photoelectron Spectroscopy (XPS), binding energies and intensities of core level peaks are commonly used for chemical analysis of solid surfaces, after subtraction of a background signal. This background due to photoelectron energy losses to electronic excitations in the solid (surface and bulk plasmon excitation, inter band transitions) contains valuable information related to the near surface dielectric function ɛ(ħω). In this work, the sensitivity of Photoelectron Energy Loss Spectroscopy (PEELS) is investigated using a model system, namely the well-controlled surface reconstruction of diamond. Boron-doped microcrystalline thin films with a mixture of (1 1 1) and (1 0 0) preferential orientations were characterized in the as-grown state, with a partially hydrogenated surface, and after annealing at 1150 °C in ultra high vacuum. After annealing, the bulk (σ + π) plasmon of diamond at 34.5 eV is weakly attenuated but no evidence for surface graphitization is observed near 6 eV, as confirmed by electronic properties. Unexpected features which appear at 10 ± 1 eV and 19 ± 1 eV in the energy loss distribution are well described by simulation of surface plasmon excitations in graphite-like materials; alternatively, they also coincide with experimental inter band transition losses in some graphene layers. This comparative study shows that the PEELS technique gives a clear signature of weak effects in the diamond surface reconstruction, even in the absence of graphitization. It confirms the sensitivity of PEELS acquisition with standard XPS equipment as a complementary tool for surface analysis.

  20. High-Resolution Electron Energy-Loss Spectroscopy (HREELS) Using a Monochromated TEM/STEM

    NASA Technical Reports Server (NTRS)

    Sai, Z. R.; Bradley, J. P.; Erni, R.; Browning, N.

    2005-01-01

    A 200 keV FEI TF20 XT monochromated (scanning) transmission electron microscope funded by NASA's SRLIDAP program is undergoing installation at Lawrence Livermore National Laboratory. Instrument specifications in STEM mode are Cs =1.0 mm, Cc =1.2 mm, image resolution =0.18 nm, and in TEM mode Cs =1.3 mm, Cc =1.3 mm, information limit =0.14 nm. Key features of the instrument are a voltage-stabilized high tension (HT) supply, a monochromator, a high-resolution electron energy-loss spectrometer/energy filter, a high-resolution annular darkfield detector, and a solid-state x-ray energy-dispersive spectrometer. The high-tension tank contains additional sections for 60Hz and high frequency filtering, resulting in an operating voltage of 200 kV plus or minus 0.005V, a greater than 10-fold improvement over earlier systems. The monochromator is a single Wien filter design. The energy filter is a Gatan model 866 Tridiem-ERS high resolution GIF spec d for less than or equal to 0.15 eV energy resolution with 29 pA of current in a 2 nm diameter probe. 0.13 eV has already been achieved during early installation. The x-ray detector (EDAX/Genesis 4000) has a take-off angle of 20 degrees, an active area of 30 square millimeters, and a solid angle of 0.3 steradians. The higher solid angle is possible because the objective pole-piece allows the detector to be positioned as close as 9.47 mm from the specimen. The voltage-stabilized HT supply, monochromator and GIF enable high-resolution electron energy-loss spectroscopy (HREELS) with energy resolution comparable to synchrotron XANES, but with approximately 100X better spatial resolution. The region between 0 and 100 eV is called the low-loss or valence electron energy-loss spectroscopy (VEELS) region where features due to collective plasma oscillations and single electron transitions of valence electrons are observed. Most of the low-loss VEELS features we are detecting are being observed for the first time in IDPs. A major focus of

  1. Electron energy-loss spectroscopy of V₂O₅ nanofibers synthesized by electro-spinning.

    PubMed

    Carrillo-Flores, D M; Ochoa-Lara, M T; Espinosa-Magaña, F

    2013-01-01

    The dielectric properties of V₂O₅ nanofibers, synthesized by the electrospinning method, are studied by analyzing the low-loss region of the electron energy loss spectroscopy (EELS) in a transmission electron microscope. A comparison of experimental EELS spectra and ab initio density-functional theory calculations (WIEN2k code) within the Generalized Gradient Approximation (GGA) is presented, having found an excellent agreement between them. Although the experimental EELS has been acquired for the nanoparticles composing the fibers, and numerical calculations were carried out for bulk material, agreement between experimental and calculated results shows that no difference exists between the electronic structure in calculated bulk material and the nanoparticles. Furthermore, our results from EELS confirm that we accomplished the expected crystalline phase. The origins of interband transitions are identified in the electronic band structure by calculating the partial imaginary part of the dielectric function and the partial density of states. PMID:23972604

  2. A Monte Carlo study of reflection electron energy loss spectroscopy spectrum of a carbon contaminated surface

    SciTech Connect

    Da, B.; Li, Z. Y.; Chang, H. C.; Ding, Z. J.; Mao, S. F.

    2014-09-28

    It has been experimentally found that the carbon surface contamination influences strongly the spectrum signals in reflection electron energy loss spectroscopy (REELS) especially at low primary electron energy. However, there is still little theoretical work dealing with the carbon contamination effect in REELS. Such a work is required to predict REELS spectrum for layered structural sample, providing an understanding of the experimental phenomena observed. In this study, we present a numerical calculation result on the spatially varying differential inelastic mean free path for a sample made of a carbon contamination layer of varied thickness on a SrTiO{sub 3} substrate. A Monte Carlo simulation model for electron interaction with a layered structural sample is built by combining this inelastic scattering cross-section with the Mott's cross-section for electron elastic scattering. The simulation results have clearly shown that the contribution of the electron energy loss from carbon surface contamination increases with decreasing primary energy due to increased individual scattering processes along trajectory parts carbon contamination layer. Comparison of the simulated spectra for different thicknesses of the carbon contamination layer and for different primary electron energies with experimental spectra clearly identifies that the carbon contamination in the measured sample was in the form of discontinuous islands other than the uniform film.

  3. Density Functional Theory Modeling of Low-Loss Electron Energy-Loss Spectroscopy in Wurtzite III-Nitride Ternary Alloys.

    PubMed

    Eljarrat, Alberto; Sastre, Xavier; Peiró, Francesca; Estradé, Sónia

    2016-06-01

    In the present work, the dielectric response of III-nitride semiconductors is studied using density functional theory (DFT) band structure calculations. The aim of this study is to improve our understanding of the features in the low-loss electron energy-loss spectra of ternary alloys, but the results are also relevant to optical and UV spectroscopy results. In addition, the dependence of the most remarkable features with composition is tested, i.e. applying Vegard's law to band gap and plasmon energy. For this purpose, three wurtzite ternary alloys, from the combination of binaries AlN, GaN, and InN, were simulated through a wide compositional range (i.e., Al x Ga1-x N, In x Al1-x N, and In x Ga1-x N, with x=[0,1]). For this DFT calculations, the standard tools found in Wien2k software were used. In order to improve the band structure description of these semiconductor compounds, the modified Becke-Johnson exchange-correlation potential was also used. Results from these calculations are presented, including band structure, density of states, and complex dielectric function for the whole compositional range. Larger, closer to experimental values, band gap energies are predicted using the novel potential, when compared with standard generalized gradient approximation. Moreover, a detailed analysis of the collective excitation features in the dielectric response reveals their compositional dependence, which sometimes departs from a linear behavior (bowing). Finally, an advantageous method for measuring the plasmon energy dependence from these calculations is explained. PMID:26868876

  4. Automated background subtraction technique for electron energy-loss spectroscopy and application to semiconductor heterostructures.

    PubMed

    Angadi, Veerendra C; Abhayaratne, Charith; Walther, Thomas

    2016-05-01

    Electron energy-loss spectroscopy (EELS) has become a standard tool for identification and sometimes also quantification of elements in materials science. This is important for understanding the chemical and/or structural composition of processed materials. In EELS, the background is often modelled using an inverse power-law function. Core-loss ionization edges are superimposed on top of the dominating background, making it difficult to quantify their intensities. The inverse power-law has to be modelled for each pre-edge region of the ionization edges in the spectrum individually rather than for the entire spectrum. To achieve this, the prerequisite is that one knows all core losses possibly present. The aim of this study is to automatically detect core-loss edges, model the background and extract quantitative elemental maps and profiles of EELS, based on several EELS spectrum images (EELS SI) without any prior knowledge of the material. The algorithm provides elemental maps and concentration profiles by making smart decisions in selecting pre-edge regions and integration ranges. The results of the quantification for a semiconductor thin film heterostructure show high chemical sensitivity, reasonable group III/V intensity ratios but also quantification issues when narrow integration windows are used without deconvolution. PMID:26998582

  5. Electron energy loss spectroscopy of excitons in two-dimensional-semiconductors as a function of temperature

    NASA Astrophysics Data System (ADS)

    Tizei, Luiz H. G.; Lin, Yung-Chang; Lu, Ang-Yu; Li, Lain-Jong; Suenaga, Kazu

    2016-04-01

    We have explored the benefits of performing monochromated Electron Energy Loss Spectroscopy (EELS) in samples at cryogenic temperatures. As an example, we have observed the excitonic absorption peaks in single layer Transition Metal Dichalcogenides. These peaks appear separated by small energies due to spin orbit coupling. We have been able to distinguish the split for MoS2 below 300 K and for MoSe2 below 220 K. However, the distinction between peaks is only clear at 150 K. We have measured the change in absorption threshold between 150 K and 770 K for MoS2 and MoSe2. We discuss the effect of carbon and ice contamination in EELS spectra. The increased spectral resolution available made possible with modern monochromators in electron microscopes will require the development of stable sample holders which reaches temperatures far below that of liquid nitrogen.

  6. Visualizing plasmon coupling in closely spaced chains of Ag nanoparticles by electron energy-loss spectroscopy.

    PubMed

    Song, Fengqi; Wang, Tingyu; Wang, Xuefeng; Xu, Changhui; He, Longbing; Wan, Jianguo; Van Haesendonck, Christian; Ringer, Simon P; Han, Min; Liu, Zongwen; Wang, Guanghou

    2010-02-01

    Anisotropic plasmon coupling in closely spaced chains of Ag nanoparticles is visualized using electron energy-loss spectroscopy in a scanning transmission electron microscope. For dimers as the simplest chain, mapping the plasmon excitations with nanometer spatial resolution and an energy resolution of 0.27 eV intuitively identifies two coupling plasmons. The in-phase mode redshifts from the ultraviolet region as the interparticle spacing is reduced, reaching the visible range at 2.7 eV. Calculations based on the discrete-dipole approximation confirm its optical activeness, where the longitudinal direction is constructed as the path for light transportation. Two coupling paths are then observed in an inflexed four-particle chain. PMID:20077517

  7. Electron energy loss spectroscopy on semiconductor heterostructures for optoelectronics and photonics applications.

    PubMed

    Eljarrat, A; López-Conesa, L; Estradé, S; Peiró, F

    2016-05-01

    In this work, we present characterization methods for the analysis of nanometer-sized devices, based on silicon and III-V nitride semiconductor materials. These methods are devised in order to take advantage of the aberration corrected scanning transmission electron microscope, equipped with a monochromator. This set-up ensures the necessary high spatial and energy resolution for the characterization of the smallest structures. As with these experiments, we aim to obtain chemical and structural information, we use electron energy loss spectroscopy (EELS). The low-loss region of EELS is exploited, which features fundamental electronic properties of semiconductor materials and facilitates a high data throughput. We show how the detailed analysis of these spectra, using theoretical models and computational tools, can enhance the analytical power of EELS. In this sense, initially, results from the model-based fit of the plasmon peak are presented. Moreover, the application of multivariate analysis algorithms to low-loss EELS is explored. Finally, some physical limitations of the technique, such as spatial delocalization, are mentioned. PMID:26366876

  8. Oxygen diffusion from anodic surface oxide films on titanium subhydride studied by auger electron spectroscopy and electron energy loss spectroscopy

    SciTech Connect

    Wang, P.S.; Wittberg, T.N.; Wolf, J.D.; Keil, R.G.

    1984-01-01

    In the present study, TiH/sub x/ (0.5 < x < 1.7) samples were prepared from titanium foil in order to study the diffusion of oxygen in the titanium subhydride. An anodic oxide, 1000A thick, was grown on the titanium subhydride foils in an aqueous saturated solution of ammonium tetraborate. These anodized samples were then heat treated at temperatures between 500 and 600/sup 0/C and changes in the profile of oxygen concentration as a function of depth were monitored using AES. From this data then it was possible to calculate the diffusivity of oxygen in the titanium subhydride. It was also found that electron energy loss spectroscopy (EELS) could be used to determine the titanium subhydride stoichiometry in the near-surface region. This was done by measuring the energy of the bulk plasmon loss peak, which for TiH/sub x/, varies linearly with hydrogen content. The amount of dehydriding which had occurred following a given heat treatment could be determined from profiles of the plasmon loss energy as a function of depth. A sample of anodized TiH/sub 0/ /sub 87/ was studied in some detail. Significant dehydriding of this sample for heat treatment times of less than one hour, only occurred at temperatures above 550/sup 0/C. Likewise, oxide dissolution was only significant at temperatures greater than 550/sup 0/C. In general, for the heat treatment parameters which were chosen, the diffusivity of oxygen in TiH/sub 0/ /sub 87/ was about an order of magnitude lower than that for oxygen in titanium.

  9. Electron Energy Loss Spectroscopy imaging of surface plasmons at the nanometer scale.

    PubMed

    Colliex, Christian; Kociak, Mathieu; Stéphan, Odile

    2016-03-01

    Since their first realization, electron microscopes have demonstrated their unique ability to map with highest spatial resolution (sub-atomic in most recent instruments) the position of atoms as a consequence of the strong scattering of the incident high energy electrons by the nuclei of the material under investigation. When interacting with the electron clouds either on atomic orbitals or delocalized over the specimen, the associated energy transfer, measured and analyzed as an energy loss (Electron Energy Loss Spectroscopy) gives access to analytical properties (atom identification, electron states symmetry and localization). In the moderate energy-loss domain (corresponding to an optical spectral domain from the infrared (IR) to the rather far ultra violet (UV), EELS spectra exhibit characteristic collective excitations of the rather-free electron gas, known as plasmons. Boundary conditions, such as surfaces and/or interfaces between metallic and dielectric media, generate localized surface charge oscillations, surface plasmons (SP), which are associated with confined electric fields. This domain of research has been extraordinarily revived over the past few years as a consequence of the burst of interest for structures and devices guiding, enhancing and controlling light at the sub-wavelength scale. The present review focuses on the study of these surface plasmons with an electron microscopy-based approach which associates spectroscopy and mapping at the level of a single and well-defined nano-object, typically at the nanometer scale i.e. much improved with respect to standard, and even near-field, optical techniques. After calling to mind some early studies, we will briefly mention a few basic aspects of the required instrumentation and associated theoretical tools to interpret the very rich data sets recorded with the latest generation of (Scanning)TEM microscopes. The following paragraphs will review in more detail the results obtained on simple planar and

  10. Advantages of a monochromator for bandgap measurements using electron energy-loss spectroscopy.

    PubMed

    Kimoto, Koji; Kothleitner, Gerald; Grogger, Werner; Matsui, Yoshio; Hofer, Ferdinand

    2005-01-01

    The practical advantages of a monochromator for electron energy-loss spectroscopy (EELS) in transmission electron microscopy are reviewed. The zero-loss peaks (ZLPs) of a monochromator and a cold field emission gun are compared in terms of bandgap measurement performance. The intensity of the ZLP tails at the bandgap energy is more important than the full-width at half maximum of the ZLP, and a monochromator is preferable to conventional electron sources. The silicon bandgap of 1.1eV is evaluated from the onset in the EEL spectrum obtained using the monochromator without a numerical procedure. We also show a high-speed instability-correction technique to realize the inherent energy resolution of the monochromator, in which instabilities of less than 335Hz are corrected using 512 EEL spectra obtained with an exposure time of 1.4ms. It will be useful in bandgap measurements and advanced studies for elucidating sub-eV EEL spectra. PMID:15629650

  11. A Complete Overhaul of the Electron Energy-Loss Spectroscopy and X-Ray Absorption Spectroscopy Database: eelsdb.eu.

    PubMed

    Ewels, Philip; Sikora, Thierry; Serin, Virginie; Ewels, Chris P; Lajaunie, Luc

    2016-06-01

    The electron energy-loss spectroscopy (EELS) and X-ray absorption spectroscopy (XAS) database has been completely rewritten, with an improved design, user interface, and a number of new tools. The database is accessible at https://eelsdb.eu/ and can now be used without registration. The submission process has been streamlined to encourage spectrum submissions and the new design gives greater emphasis on contributors' original work by highlighting their papers. With numerous new filters and a powerful search function, it is now simple to explore the database of several hundred EELS and XAS spectra. Interactive plots allow spectra to be overlaid, facilitating online comparison. An application-programming interface has been created, allowing external tools and software to easily access the information held within the database. In addition to the database itself, users can post and manage job adverts and read the latest news and events regarding the EELS and XAS communities. In accordance with the ongoing drive toward open access data increasingly demanded by funding bodies, the database will facilitate open access data sharing of EELS and XAS spectra. PMID:26899024

  12. Revealing the electronic structure of the iron pnictides with electron energy-loss spectroscopy

    NASA Astrophysics Data System (ADS)

    Idrobo, J. C.; Zhou, W.; Chisholm, M. F.; Prange, M. P.; Sefat, A. S.; McGuire, M. A.; Sales, B. C.; Pennycook, S. J.; Pantelides, S. T.

    2011-03-01

    We report electron energy-loss spectroscopy (EELS) studies of the parent compounds (LnFeAsO, Ln=La, Ce, Pr, Nd, Sm, Gd) using scanning transmission electron microscopy. We find that all the studied LnFeAsO present a Fe L-edge fine structure closer to that of metallic iron than iron oxides. We observe a direct correlation between the Fe valence state (obtained from EELS) and TC , i.e. the smaller the calculated Fe valence state, the larger is the TC for that compound. We also find an anomalous crystallographic orientation-dependence of the Ln M45 edge fine structure. In particular, we find difference in the apparent crystal field splitting of Ce and Gd f- bands when the spectra are collected parallel and perpendicular to the c-axis. This research was partially supported by NSF Grant No. DMR-0938330 (JCI, WZ), by ORNL's Shared Research Equipment (SHaRE) User Facility, which is sponsored by the Office of Basic Energy Sciences, U.S. Department of Energy (JCI) and the Office of Basic Energy Sciences, Materials Sciences and Engineering Division, U.S. Department of Energy (MC, ASS, MAM, BCS & SJP), DOE grant DE- F002-09ER46554 (MP, STP), and by the McMinn Endowment (STP) at Vanderbilt University.

  13. Electron energy-loss spectroscopy of anomalous plutonium behavior in nuclear waste materials.

    PubMed

    Buck, Edgar C; Finn, Patricia A; Bates, John K

    2004-01-01

    Plutonium-enriched layer has been observed in corroded spent uranium oxide fuel (CSNF). These Pu-enriched regions were examined with analytical transmission electron microscopy combined with electron energy-loss spectroscopy (EELS). The enriched region also contained U, Am, Ru, Zr, but only minor enrichment of rare earth elements. The Pu, possibly as Pu(V) according to EELS measurements, was dispersed within re-precipitated uranium oxide (identified as U3O8) nano-crystals between U(VI) secondary phases and the CSNF surface. The U, Pu, and Am enrichment was observed in the corrosion products with tests on different nuclear fuels. This may have implications for the long-term behavior of CSNF under storage in a geologic waste repository. Furthermore, there may be an increased potential for the generation of Pu-bearing colloids from this type of weathered CSNF. PMID:15003610

  14. Electron Energy-loss Spectroscopy of Anomalous Plutonium Behavior in Nuclear Waste Materials

    SciTech Connect

    Buck, Edgar C.; Finn, patricia A.; Bates, John K.

    2004-06-01

    Plutonium-enriched layer has been observed in corroded spent uranium oxide fuel (CSNF). These Pu-enriched regions were examined with analytical transmission electron microscopy combined with electron energy-loss spectroscopy. The enriched region also contained U, Am, Ru, Zr, but only minor enrichment of rare earth elements. The Pu, possibly as Pu(V) according to EELS measurements, was dispersed within re-precipitated uranium oxide (identified as U3O8) nano-crystals between U(VI) secondary phases and the CSNF surface. The U, Pu, and Am enrichment was observed in the corrosion products with tests on different nuclear fuels. This may have implications for the long-term behavior of CSNF under storage in a geologic waste repository. Furthermore, there may be an increased potential for the generation of Pu-bearing colloids from this type of weathered CSNF.

  15. Quantification of ordering at a solid-liquid interface using plasmon electron energy loss spectroscopy

    SciTech Connect

    Gandman, Maria; Kauffmann, Yaron; Kaplan, Wayne D.

    2015-02-02

    We present an in situ electron energy loss spectroscopy (EELS) study of ordering of liquid Al at various Al-Al{sub 2}O{sub 3} interfaces. This technique utilizes precise measurements of the shifts in bulk plasmon resonance and their sensitivity to the valence electron density. Plasmon EELS combined with high resolution transmission electron microscopy provides information regarding the chemical composition in liquid Al at Al-Al{sub 2}O{sub 3} interfaces. Preferential oxygen segregation to the (0006) Al{sub 2}O{sub 3} plane was verified, and the (101{sup ¯}2) Al{sub 2}O{sub 3} plane was found to contain the lowest amount of segregated species.

  16. Electron energy loss spectroscopy of plasmon resonances in titanium nitride thin films

    NASA Astrophysics Data System (ADS)

    Herzing, Andrew A.; Guler, Urcan; Zhou, Xiuli; Boltasseva, Alexandra; Shalaev, Vladimir; Norris, Theodore B.

    2016-04-01

    The plasmon resonance characteristics of refractory TiN thin films were analyzed using electron energy-loss spectroscopy (EELS). A bulk plasmon resonance was observed at 2.81 eV and a weaker surface plasmon resonance peak was detected at 2.05 eV. These findings are compared to finite-difference time-domain simulations based on measured optical data. The calculated values for both the bulk and surface resonances (2.74 eV and 2.15 eV, respectively) show reasonable agreement with those measured via EELS. The amplitude of the experimentally observed surface resonance was weaker than that typically encountered in noble metal nanostructures, and this is discussed in the context of electron density and reduced spatial confinement of the resonance mode in the thin-film geometry.

  17. Transformation Optics: A Time- and Frequency-Domain Analysis of Electron-Energy Loss Spectroscopy.

    PubMed

    Kraft, Matthias; Luo, Yu; Pendry, J B

    2016-08-10

    Electron energy loss spectroscopy (EELS) and cathodoluminescence (CL) play a pivotal role in many of the cutting edge experiments in plasmonics. EELS and CL experiments are usually supported by numerical simulations, which-though accurate-may not provide as much physical insight as analytical calculations do. Fully analytical solutions to EELS and CL systems in plasmonics are rare and difficult to obtain. This paper aims to narrow this gap by introducing a new method based on transformation optics that allows to calculate the quasistatic frequency- and time-domain response of plasmonic particles under electron beam excitation. We study a nonconcentric annulus (and ellipse in the Supporting Information ) as an example. PMID:27380143

  18. Detection of water and its derivatives on individual nanoparticles using vibrational electron energy-loss spectroscopy.

    PubMed

    Crozier, Peter A; Aoki, Toshihiro; Liu, Qianlang

    2016-10-01

    Understanding the role of water, hydrate and hydroxyl species on nanoparticle surfaces and interfaces is very important in both physical and life sciences. Detecting the presence of oxygen-hydrogen species with nanometer resolution is extremely challenging at present. Here we show that the recently developed vibrational electron energy-loss spectroscopy using subnanometer focused electron beams can be employed to spectroscopically identify the local presence and variation of OH species on nanoscale surfaces. The hydrogen-oxygen fingerprint can be correlated with highly localized structural and morphological information obtained from electron imaging. Moreover, the current approach exploits the aloof beam mode of spectral acquisition which does not require direct electron irradiation of the sample thus greatly reducing beam damage to the OH bond. These findings open the door for using electron microscopy to probe local hydroxyl and hydrate species on nanoscale organic and inorganic structures. PMID:27423795

  19. Electron energy loss spectroscopy techniques for the study of microbial chromium(VI) reduction

    NASA Technical Reports Server (NTRS)

    Daulton, Tyrone L.; Little, Brenda J.; Lowe, Kristine; Jones-Meehan, Joanne

    2002-01-01

    Electron energy loss spectroscopy (EELS) techniques were used to determine oxidation state, at high spatial resolution, of chromium associated with the metal-reducing bacteria, Shewanella oneidensis, in anaerobic cultures containing Cr(VI)O4(2-). These techniques were applied to fixed cells examined in thin section by conventional transmission electron microscopy (TEM) as well as unfixed, hydrated bacteria examined by environmental cell (EC)-TEM. Two distinct populations of bacteria were observed by TEM: bacteria exhibiting low image contrast and bacteria exhibiting high contrast in their cell membrane (or boundary) structure which was often encrusted with high-contrast precipitates. Measurements by EELS demonstrated that cell boundaries became saturated with low concentrations of Cr and the precipitates encrusting bacterial cells contained a reduced form of Cr in oxidation state + 3 or lower.

  20. Oxidation of diamond films by atomic oxygen: High resolution electron energy loss spectroscopy studies

    NASA Astrophysics Data System (ADS)

    Shpilman, Z.; Gouzman, I.; Grossman, E.; Akhvlediani, R.; Hoffman, A.

    2007-12-01

    Diamond surface oxidation by atomic oxygen, annealing up to ˜700°C, and in situ exposure to thermally activated hydrogen were studied by high resolution electron energy loss spectroscopy (HREELS). After atomic oxygen (AO) exposure, HREELS revealed peaks associated with CHx groups, carbonyl, ether, and peroxide-type species and strong quenching of the diamond optical phonon and its overtones. Upon annealing of the oxidized surfaces, the diamond optical phonon overtones at 300 and 450meV emerge and carbonyl and peroxide species gradually desorb. The diamond surface was not completely regenerated after annealing to ˜700°C and in situ exposure to thermally activated hydrogen, probably due to the irreversible deterioration of the surface by AO.

  1. Electronic structure of Fe-based amorphous alloys studied using electron-energy-loss spectroscopy

    NASA Astrophysics Data System (ADS)

    Wang, H. J.; Gu, X. J.; Poon, S. J.; Shiflet, G. J.

    2008-01-01

    The local atomic electronic structures of Fe-Mo-C-B metallic glasses are investigated using electron energy-loss spectroscopy (EELS). The fracture behavior of this Fe-based amorphous alloy system undergoes the transition from being ductile to exhibiting brittleness when alloyed with Cr or Er atoms. In addition, the glass-forming ability is also enhanced. This plastic-to-brittle transition is suggested to correlate with the change of local atomic short-range order or bonding configurations. Therefore, the bonding configuration of Fe-Mo-C-B-Er(Cr) amorphous alloys is investigated by studying the electronic structure of Fe and C atoms using electron energy-loss spectroscopy. It is shown that the normalized EELS white line intensities of Fe-L2,3 edges decrease slightly with an increasing amount of Er additions, while no noticeable difference is obtained with Cr additions. As for the C K edge, a prominent change of edge shape is observed for both alloy systems, where the first peak corresponding to a 1s→1π* transition increases with increasing Er and Cr additions. Accordingly, it is concluded that changes in the local atomic and electronic structure occur around Fe and C atoms when Er and Cr are introduced into the alloys. Furthermore, it is pointed out that the formation of Er-C and Cr-C carbide like local order inferred from the observed C K edge spectra can provide a plausible explanation for the plastic-to-brittle transition observed in these Fe-based amorphous alloys. In spite of the complexity of electronic and atomic structure in this multicomponent Fe-based metallic glass system, this study could serve as a starting point for providing a qualitative interpretation between electronic structure and plasticity in the Fe-Mo-C-B amorphous alloy system. Complimentary techniques, such as x-ray diffraction and high-resolution transmission electron microscope are also employed, providing a more complete structural characterization.

  2. Electron energy loss and thermal desorption spectroscopy of pyridine adsorbed on Pt(111)

    SciTech Connect

    Grassian, V.H.; Muetterties, E.L.

    1986-10-23

    The chemisorption behavior of pyridine (NC/sub 5/H/sub 5/) on a Pt(111) surface has been examined by using thermal desorption and electron energy loss spectroscopy as a function of adsorption temperature. The vibrational spectrum of pyridine adsorbed to room temperature on this surface shows intense loss peaks in the specular direction from vibrational modes which can be characterized as in-plane stretching and bending modes. This vibrational spectrum has been interpreted as the formation of an ..cap alpha..-pyridyl species (NC/sub 5/H/sub 4/) on the surface. The pyridyl moiety is bonded to the platinum surface through the nitrogen and one of the ..cap alpha..-carbon atoms with the pyridyl plane perpendicular to the metal surface. When pyridine is adsorbed at low temperature (120 K), it bonds to the surface through both the nitrogen atom and the ..pi.. and ..pi../sup */ orbitals of the pyridine ring. As the crystal is warmed to 260 K, at saturation coverage, approximately 50% of the molecules desorb as molecular pyridine. The remaining pyridine molecules partially decompose on the surface to form an ..cap alpha..-pyridyl fragment. The electron energy loss spectra of pyridine adsorbed at both low and room temperature is compared to the infrared spectra of two osmium cluster compounds: Os/sub 3/(CO)/sub 11/(NC/sub 5/H/sub 5/), a pyridine complex, and HOs/sub 3/(CO)/sup 18/NC/sub 5/H/sub 4/), a pyridyl complex.

  3. Study of the Dielectric Function of Graphene from Spectroscopic Ellipsometry and Electron Energy Loss Spectroscopy

    NASA Astrophysics Data System (ADS)

    Nelson, Florence

    For more than 60 years, semiconductor research has been advancing up the periodic table. The first transistor was made from germanium. This later gave way to silicon-based devices due to the latter's ability to form an excellent interface with thermally-grown oxide. Now for the last ˜8 years, the focus has moved up one more row to carbon for post-CMOS devices in order to comply with the scaling limitations of Moore's law. However, for each of these, the measurements of film properties and dimensions have always been required for technological applications. These measurement methods often incorporate the use of light or electrons in order to take advantage of a wavelength that is on the order of, or smaller than, the feature sizes of interest. This thesis compares the dielectric function of graphene measured by an optical method to that obtained from an electron energy loss method in order to observe the effect of contamination and substrate on the optical properties of graphene exposed to the environment. Whether viewed in terms of how light affects a material (dielectric function) or how a material affects light (refractive index), the optical response is a quantity that may be used to obtain information about a film's thickness, energy structure, and the types of excitations that are responsible for energy loss. The three main experimental methods used in this thesis work are spectroscopic ellipsometry (SE), scanning transmission electron microscopy (STEM), and electron energy loss spectroscopy (EELS). SE is commonly used in clean-room environments for optical measurement over the energy range of ˜0-5 eV. This method is used to study graphene's dielectric function from the ultraviolet (UV) through infrared (IR) regions through use of an oscillator dispersion model. A nearly constant absorbance over the IR and into the visible region is observed due to vertical transitions between graphene's linearly dispersed pi-bands at the Dirac points. An exciton

  4. 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.

  5. 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

  6. Valence electron energy-loss spectroscopy study of ZrSiO₄ and ZrO₂.

    PubMed

    Jiang, Nan; Spence, John C H

    2013-11-01

    ZrSiO4 (zircon) and m-ZrO2 (zirconia) are fundamental and industrially important materials. This work reports the detailed valence electron energy-loss spectroscopy (VEELS) studies of these compounds. The dielectric response functions, as well as single-electron interband transition spectra, are derived from VEELS data for both ZrSiO4 and m-ZrO2, in the range 5-50 eV using the Kramers-Kronig analysis method. Our interpretation of the interband transitions is given with the aid of ab initio calculations of density of states. The bandgap energies for both materials are also measured using VEELS. The surface and bulk plasmons are identified: the surface plasmon peaks locate at around 12 eV, and two bulk plasmon peaks are ∼15-16 eV and ∼25-27 eV, respectively. Although similarities in the VEELS exist between ZrSiO4 and m-ZrO2, two major differences are also noticed and explained in terms of composition and structure differences. PMID:23916829

  7. Electronic excitation of furfural as probed by high-resolution vacuum ultraviolet spectroscopy, electron energy loss spectroscopy, and ab initio calculations

    NASA Astrophysics Data System (ADS)

    Ferreira da Silva, F.; Lange, E.; Limão-Vieira, P.; Jones, N. C.; Hoffmann, S. V.; Hubin-Franskin, M.-J.; Delwiche, J.; Brunger, M. J.; Neves, R. F. C.; Lopes, M. C. A.; de Oliveira, E. M.; da Costa, R. F.; Varella, M. T. do N.; Bettega, M. H. F.; Blanco, F.; García, G.; Lima, M. A. P.; Jones, D. B.

    2015-10-01

    The electronic spectroscopy of isolated furfural (2-furaldehyde) in the gas phase has been investigated using high-resolution photoabsorption spectroscopy in the 3.5-10.8 eV energy-range, with absolute cross section measurements derived. Electron energy loss spectra are also measured over a range of kinematical conditions. Those energy loss spectra are used to derive differential cross sections and in turn generalised oscillator strengths. These experiments are supported by ab initio calculations in order to assign the excited states of the neutral molecule. The good agreement between the theoretical results and the measurements allows us to provide the first quantitative assignment of the electronic state spectroscopy of furfural over an extended energy range.

  8. Electronic excitation of furfural as probed by high-resolution vacuum ultraviolet spectroscopy, electron energy loss spectroscopy, and ab initio calculations.

    PubMed

    Ferreira da Silva, F; Lange, E; Limão-Vieira, P; Jones, N C; Hoffmann, S V; Hubin-Franskin, M-J; Delwiche, J; Brunger, M J; Neves, R F C; Lopes, M C A; de Oliveira, E M; da Costa, R F; Varella, M T do N; Bettega, M H F; Blanco, F; García, G; Lima, M A P; Jones, D B

    2015-10-14

    The electronic spectroscopy of isolated furfural (2-furaldehyde) in the gas phase has been investigated using high-resolution photoabsorption spectroscopy in the 3.5-10.8 eV energy-range, with absolute cross section measurements derived. Electron energy loss spectra are also measured over a range of kinematical conditions. Those energy loss spectra are used to derive differential cross sections and in turn generalised oscillator strengths. These experiments are supported by ab initio calculations in order to assign the excited states of the neutral molecule. The good agreement between the theoretical results and the measurements allows us to provide the first quantitative assignment of the electronic state spectroscopy of furfural over an extended energy range. PMID:26472380

  9. Electronic excitation of furfural as probed by high-resolution vacuum ultraviolet spectroscopy, electron energy loss spectroscopy, and ab initio calculations

    SciTech Connect

    Ferreira da Silva, F.; Lange, E.; Limão-Vieira, P. E-mail: michael.brunger@flinders.edu.au; Jones, N. C.; Hoffmann, S. V.; Hubin-Franskin, M.-J.; Delwiche, J.; Brunger, M. J. E-mail: michael.brunger@flinders.edu.au; and others

    2015-10-14

    The electronic spectroscopy of isolated furfural (2-furaldehyde) in the gas phase has been investigated using high-resolution photoabsorption spectroscopy in the 3.5–10.8 eV energy-range, with absolute cross section measurements derived. Electron energy loss spectra are also measured over a range of kinematical conditions. Those energy loss spectra are used to derive differential cross sections and in turn generalised oscillator strengths. These experiments are supported by ab initio calculations in order to assign the excited states of the neutral molecule. The good agreement between the theoretical results and the measurements allows us to provide the first quantitative assignment of the electronic state spectroscopy of furfural over an extended energy range.

  10. Electronic and optical properties of selected polymers studied by reflection electron energy loss spectroscopy

    NASA Astrophysics Data System (ADS)

    Tahir, Dahlang; Tougaard, Sven

    2012-03-01

    We have determined the electronic and optical properties of six polymers: Polymethyl-methacrylate (PMMA), polyethylene (PE), polyvinyl chloride (PVC), polyester (PET), polypyrrole (PPY), and polyamide (PA6) for energy losses from 0 to 70 eV by analysis of reflection electron energy-loss spectroscopy (REELS) spectra. We found that the surface was easily damaged by the incident electron beam, in particular for energies above 500 eV. The damage results in new peaks in the bandgap region and the polymers become metallic. Great care was exerted to determine experimental conditions under which these effects are minimized. The REELS spectra were corrected for multiple inelastically scattered electrons with the QUASES-XS-REELS software to determine the effective inelastic-scattering cross sections. From these cross sections, we found that the band gaps for PMMA, PE, PVC, PET, PPY, and PA6 are 5.0 eV, 7.5 eV, 7.0 eV, 3.0 eV, 3.5 eV, and 5.1 eV, respectively. Quantitative analysis of the experimental cross sections was carried out by using the QUEELS-ɛ(k,ω)-REELS software to determine the dielectric function and optical properties. This is done by comparing the experimental REELS inelastic electron-scattering cross-section with a simulated cross section in which the only input is Im(-1/ɛ). The dielectric function is expressed as a sum of oscillators and the oscillator parameters are determined. Good agreement between the experimental and theoretical cross section is achieved for all polymers. From Im(-1/ɛ), the real and imaginary parts of ɛ (ω), the refractive index, and the extinction coefficient were determined for all polymers in the energy range ћω = 0 to 70 eV. An oscillator is clearly observed for PPY, PET, and PA6 at ˜ 6.7 eV, which corresponds to the π plasmon. This oscillator is not found for PMMA, PE, and PVC. A set of oscillators in the 20-30 eV energy range corresponding to the σ+π plasmon is found for all polymers.

  11. Derivation of optical properties of carbonaceous aerosols by monochromated electron energy-loss spectroscopy.

    PubMed

    Zhu, Jiangtao; Crozier, Peter A; Ercius, Peter; Anderson, James R

    2014-06-01

    Monochromated electron energy-loss spectroscopy (EELS) is employed to determine the optical properties of carbonaceous aerosols from the infrared to the ultraviolet region of the spectrum. It is essential to determine their optical properties to understand their accurate contribution to radiative forcing for climate change. The influence of surface and interface plasmon effects on the accuracy of dielectric data determined from EELS is discussed. Our measurements show that the standard thin film formulation of Kramers-Kronig analysis can be employed to make accurate determination of the dielectric function for carbonaceous particles down to about 40 nm in size. The complex refractive indices of graphitic and amorphous carbon spherules found in the atmosphere were determined over the wavelength range 200-1,200 nm. The graphitic carbon was strongly absorbing black carbon, whereas the amorphous carbon shows a more weakly absorbing brown carbon profile. The EELS approach provides an important tool for exploring the variation in optical properties of atmospheric carbon. PMID:24735494

  12. Determination of Elemental Ratio in an Atomic Column by Electron Energy Loss Spectroscopy.

    PubMed

    Haruta, Mitsutaka; Hosaka, Yoshiteru; Ichikawa, Noriya; Saito, Takashi; Shimakawa, Yuichi; Kurata, Hiroki

    2016-07-26

    Atomic-resolution quantification of the elemental ratio of Fe to Mn at the octahedral and tetrahedral sites in brownmillerite Ca2Fe1.07Mn0.93O5 was determined using electron energy-loss spectroscopy combined with aberration-corrected scanning transmission electron microscopy. The combined techniques revealed that oversampling of the spectral imaging data yielded a spatially resolved area that very nearly reflects atomic resolution (∼1.2 Å radius). The average experimental ratios of Fe to Mn within this region were 17.5:82.5 for the octahedral sites and 81.6:18.4 for the tetrahedral sites. The elemental ratio in an octahedral atomic column was successfully extracted by estimating the mixing of signals from nearest neighbor columns. The results indicated that the ratio of Fe to Mn was 13:87 at the octahedral site, which is in good agreement with the results of neutron diffraction analysis. In addition, the uncertainty of experimental results obtained by using an average 1.2 Å radius was less than 10% at octahedral sites, depending on the sample thickness. In contrast, the experimental error due to dechanneling of incident electrons was larger at the tetrahedral sites. This experimental procedure has wide application for determining the spatially resolved composition ratio of elements in perovskite-like compounds. PMID:27341006

  13. Electron energy loss spectroscopy analysis of the interaction of Cr and V with MWCNTs.

    PubMed

    Ilari, Gabriele M; Chawla, Vipin; Matam, Santhosh; Zhang, Yucheng; Michler, Johann; Erni, Rolf

    2016-05-01

    The presented scanning transmission electron microscopy (STEM) and electron energy-loss spectroscopy (EELS) results show the strong reaction of Cr and V with the graphitic walls of MWCNTs. For Vanadium, an interfacial VC layer could be observed at the interface between VN and MWCNTs, when the samples were heated in situ to 750°C. Knowledge about this interfacial VC layer is important for the formation of VN-MWCNT hybrid materials, used in supercapacitor electrodes, often synthesized at high temperatures. Chromium reacts at 500°C with the MWCNTs to form Cr3C2 and in some cases, dissolved the MWCNT completely. Together with the previously published results about the interaction of MWCNTs with Cu (no interaction) and Ni (a slight rehybridisation trend for the outermost MWCNT-wall observed with EELS) (Ilari et al., 2015) the influence of the valence d-orbital occupancy of 3d transition metals on the interaction strength with CNTs is shown experimentally. For a transition metal to form chemical bonds towards CNT-walls, unoccupied states in its valence d-orbitals are needed. While Ni (2 unoccupied states) interacts only slightly, Cr (5 unoccupied states) and V (7 unoccupied states) react much stronger and can dissolve the MWCNTs, at least partially. PMID:26925830

  14. Quantification of the boron speciation in alkali borosilicate glasses by electron energy loss spectroscopy

    PubMed Central

    Cheng, Shaodong; Yang, Guang; Zhao, Yanqi; Peng, MingYing; Skibsted, Jørgen; Yue, Yuanzheng

    2015-01-01

    Transmission electron microscopy and related analytical techniques have been widely used to study the microstructure of different materials. However, few research works have been performed in the field of glasses, possibly due to the electron-beam irradiation damage. In this paper, we have developed a method based on electron energy loss spectroscopy (EELS) data acquisition and analyses, which enables determination of the boron speciation in a series of ternary alkali borosilicate glasses with constant molar ratios. A script for the fast acquisition of EELS has been designed, from which the fraction of BO4 tetrahedra can be obtained by fitting the experimental data with linear combinations of the reference spectra. The BO4 fractions (N4) obtained by EELS are consistent with those from 11B MAS NMR spectra, suggesting that EELS can be an alternative and convenient way to determine the N4 fraction in glasses. In addition, the boron speciation of a CeO2 doped potassium borosilicate glass has been analyzed by using the time-resolved EELS spectra. The results clearly demonstrate that the BO4 to BO3 transformation induced by the electron beam irradiation can be efficiently suppressed by doping CeO2 to the borosilicate glasses. PMID:26643370

  15. Electron energy-loss spectroscopy of carbon in interplanetary dust particles

    NASA Technical Reports Server (NTRS)

    Keller, Lindsay P.; Bradley, John P.; Thomas, Kathie L.; Mckay, David S.

    1994-01-01

    The nature of the carbon-bearing phases in IDP's provides information regarding the chemical and physical processes involved in the formation and evolution of the early solar system. Several carbon-bearing materials have been observed in IDP's, but details of their nature, abundance, and distribution are still poorly known. A knowledge of the abundance and nature of carbon in IDP's is useful in constraining the sources of IDP's and for comparisons with other chondritic materials. Estimates of carbon abundance in anhydrous and hydrated IDP's indicate that most of these particles have significantly higher carbon than the carbonaceous chondrites. Mineralogical analyses show that carbonates are only a minor component of most hydrated IDP's, and so the high carbon abundances in this group of IDP's indicates that other carbon-bearing phases are present in significant concentrations. Using the technique of electron energy-loss spectroscopy (EELS), we have identified two forms of carbon in a hydrated IDP, oxidized carbon (carbonates), and amorphous elemental carbon.

  16. Nanoscale Concentration Quantification of Pharmaceutical Actives in Amorphous Polymer Matrices by Electron Energy-Loss Spectroscopy.

    PubMed

    Ricarte, Ralm G; Lodge, Timothy P; Hillmyer, Marc A

    2016-07-26

    We demonstrated the use of electron energy-loss spectroscopy (EELS) to evaluate the composition of phenytoin:hydroxypropyl methylcellulose acetate succinate (HPMCAS) spin-coated solid dispersions (SDs). To overcome the inability of bright-field and high-angle annular dark-field TEM imaging to distinguish between glassy drug and polymer, we used the π-π* transition peak in the EELS spectrum to detect phenytoin within the HPMCAS matrix of the SD. The concentration of phenytoin within SDs of 10, 25, and 50 wt % drug loading was quantified by a multiple least-squares analysis. Evaluating the concentration of 50 different regions in each SD, we determined that phenytoin and HPMCAS are intimately mixed at a length scale of 200 nm, even for drug loadings up to 50 wt %. At length scales below 100 nm, the variance of the measured phenytoin concentration increases; we speculate that this increase is due to statistical fluctuations in local concentration and chemical changes induced by electron irradiation. We also performed EELS analysis of an annealed 25 wt % phenytoin SD and showed that the technique can resolve concentration differences between regions that are less than 50 nm apart. Our findings indicate that EELS is a useful tool for quantifying, with high accuracy and sub-100 nm spatial resolution, the composition of many pharmaceutical and soft matter systems. PMID:27419264

  17. Quasinormal mode theory and modelling of electron energy loss spectroscopy for plasmonic nanostructures

    NASA Astrophysics Data System (ADS)

    Ge, Rong-Chun; Hughes, Stephen

    2016-05-01

    Understanding light-matter interactions using localized surface plasmons (LSPs) is of fundamental interest in classical and quantum plasmonics and has a wide range of applications. In order to understand the spatial properties of LSPs, electron energy loss spectroscopy (EELS) is a common and powerful method of spatially resolving the extreme localized fields that can be obtained with metal resonators. However, modelling EELS for general shaped resonators presents a major challenge in computational electrodynamics, requiring the full photon Green function as a function of two space points and frequency. Here we present an intuitive and computationally simple method for computing EELS maps of plasmonic resonators using a quasinormal mode (QNM) expansion technique. By separating the contribution of the QNM and the bulk material, we give closed-form analytical formulas for the plasmonic QNM contribution to the EELS maps. We exemplify our technique for a split ring resonator, a gold nanorod, and a nanorod dimer structure. The method is accurate, intuitive, and gives orders of magnitude improvements over direct dipole simulations that numerically solve the full 3D Maxwell equations. We also show how the same QNM Green function can be used to obtain the Purcell factor (and projected local density of optical states) from quantum dipole emitters or two level atoms, and we demonstrate how the spectral features differ in general to the EELS spectrum.

  18. Fourier-ratio deconvolution techniques for electron energy-loss spectroscopy (EELS).

    PubMed

    Wang, Feng; Egerton, Ray; Malac, Marek

    2009-09-01

    We discuss several ways of using Fourier-ratio deconvolution to process low-loss spectra. They include removal of the tail arising from the zero-loss peak, extraction of the spectrum of a particle from data recorded from the particle on a substrate, separation of the bulk and surface components in spectra recorded from samples of the same composition but different thickness, and investigation of interface energy-loss modes. We also demonstrate the use of a Bayesian-equivalent procedure based on the Richardson-Lucy algorithm. PMID:19577847

  19. Effect of multipole excitations in electron energy-loss spectroscopy of surface plasmon modes in silver nanowires

    SciTech Connect

    Zhou, Xiuli; Norris, Theodore B.; Hörl, Anton; Trügler, Andreas; Hohenester, Ulrich; Herzing, Andrew A.

    2014-12-14

    We have characterized the surface plasmon resonance (SPR) in silver nanowires using spatially resolved electron energy loss spectroscopy (EELS) in the scanning transmission electron microscope. Non-symmetric EELS spectra due to high-k SPR propagation along the nanowire and spectral shifts due to higher-order mode excitation are observed when the beam is positioned near the tip of the nanowire. When the beam is far from the tip region and on the side of nanowire, no spectral shifts are observed as the beam is scanned in the radial direction of the nanowire. The experimental spectra are compared with three different theoretical approaches: direct numerical calculation of the energy loss, analytical models for energy loss, and numerical simulations using an optical model. All three models reproduce the spectral shifts as the electron beam approaches the cap of the nanowire. The analytical model reveals the origin of the shifts in high-order plasmon mode excitation.

  20. THE APPLICATION OF HIGH RESOLUTION ELECTRON ENERGY LOSS SPECTROSCOPY TO THE CHARACTERIZATION OF ADSORBED MOLECULES ON RHODIUM SINGLE CRYSTAL SURFACES

    SciTech Connect

    Dubois, L.H.; Somorjai, G.A.

    1980-01-01

    The scattering of low energy electrons by metal surfaces has been studied for many years now. The electron's ease of generation and detection and high surface sensitivity (low penetration depth) make it an ideal probe for surface scientists. The impinging electron can interact with the surface in basically two ways: it can either elastically reflect (or diffract) from the surface without losing energy or lose a portion of it's incident energy and inelastically scatter. In this paper we will be concerned with only one of many possible inelastic scattering processes: the loss of the electron's energy to the vibrational modes of atoms and molecules chemisorbed on the surface. This technique is known as high resolution electron energy loss spectroscopy (or ELS, EELS, HRELS, HREELS, etc.).

  1. Electronic properties of Mn-phthalocyanine–C{sub 60} bulk heterojunctions: Combining photoemission and electron energy-loss spectroscopy

    SciTech Connect

    Roth, Friedrich; Lupulescu, Cosmin; Darlatt, Erik; Gottwald, Alexander; Eberhardt, Wolfgang

    2015-11-14

    The electronic properties of co-evaporated mixtures (blends) of manganese phthalocyanine and the fullerene C{sub 60} (MnPc:C{sub 60}) have been studied as a function of the concentration of the two constituents using two supplementary electron spectroscopic methods, photoemission spectroscopy (PES) and electron energy-loss spectroscopy (EELS) in transmission. Our PES measurements provide a detailed picture of the electronic structure measured with different excitation energies as well as different mixing ratios between MnPc and C{sub 60}. Besides a relative energy shift, the occupied electronic states of the two materials remain essentially unchanged. The observed energy level alignment is different compared to that of the related CuPc:C{sub 60} bulk heterojunction. Moreover, the results from our EELS investigations show that, despite the rather small interface interaction, the MnPc related electronic excitation spectrum changes significantly by admixing C{sub 60} to MnPc thin films.

  2. Electronic properties of Mn-phthalocyanine-C60 bulk heterojunctions: Combining photoemission and electron energy-loss spectroscopy

    NASA Astrophysics Data System (ADS)

    Roth, Friedrich; Herzig, Melanie; Lupulescu, Cosmin; Darlatt, Erik; Gottwald, Alexander; Knupfer, Martin; Eberhardt, Wolfgang

    2015-11-01

    The electronic properties of co-evaporated mixtures (blends) of manganese phthalocyanine and the fullerene C60 (MnPc:C60) have been studied as a function of the concentration of the two constituents using two supplementary electron spectroscopic methods, photoemission spectroscopy (PES) and electron energy-loss spectroscopy (EELS) in transmission. Our PES measurements provide a detailed picture of the electronic structure measured with different excitation energies as well as different mixing ratios between MnPc and C60. Besides a relative energy shift, the occupied electronic states of the two materials remain essentially unchanged. The observed energy level alignment is different compared to that of the related CuPc:C60 bulk heterojunction. Moreover, the results from our EELS investigations show that, despite the rather small interface interaction, the MnPc related electronic excitation spectrum changes significantly by admixing C60 to MnPc thin films.

  3. Analysis of catalytic gas products using electron energy-loss spectroscopy and residual gas analysis for operando transmission electron microscopy.

    PubMed

    Miller, Benjamin K; Crozier, Peter A

    2014-06-01

    Operando transmission electron microscopy (TEM) of catalytic reactions requires that the gas composition inside the TEM be known during the in situ reaction. Two techniques for measuring gas composition inside the environmental TEM are described and compared here. First, electron energy-loss spectroscopy, both in the low-loss and core-loss regions of the spectrum was utilized. The data were quantified using a linear combination of reference spectra from individual gasses to fit a mixture spectrum. Mass spectrometry using a residual gas analyzer was also used to quantify the gas inside the environmental cell. Both electron energy-loss spectroscopy and residual gas analysis were applied simultaneously to a known 50/50 mixture of CO and CO2, so the results from the two techniques could be compared and evaluated. An operando TEM experiment was performed using a Ru catalyst supported on silica spheres and loaded into the TEM on a specially developed porous pellet TEM sample. Both techniques were used to monitor the conversion of CO to CO2 over the catalyst, while simultaneous atomic resolution imaging of the catalyst was performed. PMID:24815065

  4. Combination of electron energy-loss spectroscopy and energy dispersive x-ray spectroscopy to determine indium concentration in InGaN thin film structures

    NASA Astrophysics Data System (ADS)

    Wang, X.; Chauvat, M. P.; Ruterana, P.; Walther, T.

    2015-11-01

    We demonstrate a method to determine the indium concentration, x, of In x Ga1-x N thin films by combining plasmon excitation studies in electron energy-loss spectroscopy (EELS) with a novel way of quantification of the intensity of x-ray lines in energy-dispersive x-ray spectroscopy (EDXS). The plasmon peak in EELS of InGaN is relatively broad. We fitted a Lorentz function to the main plasmon peak to suppress noise and the influence from the neighboring Ga 3d transition in the spectrum, which improves the precision in the evaluation of the plasmon peak position. As the indium concentration of InGaN is difficult to control during high temperature growth due to partial In desorption, the nominal indium concentrations provided by the growers were not considered reliable. The indium concentration obtained from EDXS quantification using Oxford Instrument ISIS 300 x-ray standard quantification software often did not agree with the nominal indium concentration, and quantification using K and L lines was inconsistent. We therefore developed a self-consistent iterative procedure to determine the In content from thickness-dependent k-factors, as described in recent work submitted to Journal of Microscopy. When the plasmon peak position is plotted versus the indium concentration from EDXS we obtain a linear relationship over the whole compositional range, and the standard error from linear least-squares fitting shows that the indium concentration can be determined from the plasmon peak position to within Δx = ± 0.037 standard deviation.

  5. A reverse Monte Carlo method for deriving optical constants of solids from reflection electron energy-loss spectroscopy spectra

    SciTech Connect

    Da, B.; Sun, Y.; Ding, Z. J.; Mao, S. F.; Zhang, Z. M.; Jin, H.; Yoshikawa, H.; Tanuma, S.

    2013-06-07

    A reverse Monte Carlo (RMC) method is developed to obtain the energy loss function (ELF) and optical constants from a measured reflection electron energy-loss spectroscopy (REELS) spectrum by an iterative Monte Carlo (MC) simulation procedure. The method combines the simulated annealing method, i.e., a Markov chain Monte Carlo (MCMC) sampling of oscillator parameters, surface and bulk excitation weighting factors, and band gap energy, with a conventional MC simulation of electron interaction with solids, which acts as a single step of MCMC sampling in this RMC method. To examine the reliability of this method, we have verified that the output data of the dielectric function are essentially independent of the initial values of the trial parameters, which is a basic property of a MCMC method. The optical constants derived for SiO{sub 2} in the energy loss range of 8-90 eV are in good agreement with other available data, and relevant bulk ELFs are checked by oscillator strength-sum and perfect-screening-sum rules. Our results show that the dielectric function can be obtained by the RMC method even with a wide range of initial trial parameters. The RMC method is thus a general and effective method for determining the optical properties of solids from REELS measurements.

  6. Combined study of the ground and unoccupied electronic states of graphite by electron energy-loss spectroscopy

    SciTech Connect

    Feng, Zhenbao; Löffler, Stefan; Eder, Franz; Meyer, Jannik C.; Su, Dangsheng; Schattschneider, Peter

    2013-11-14

    Both the unoccupied and ground electronic states of graphite have been studied by electron energy-loss spectroscopy in a transmission electron microscope. Electron energy-loss near-edge structures of the K-edge of carbon have been investigated in detail for scattering angles from 0 to 2.8 mrad. The π{sup *} and σ{sup *} components were separated. The angular and energy dependences of the π{sup *} and σ{sup *} structures were in fair agreement with theory. Electron energy loss Compton spectra of graphite were recorded at scattering angles from 45 to 68 mrad. One Compton scattering spectrum was obtained in 1 min compared with several hours or days using photons. The contributions of core electrons were calculated by the exact Hartree-Slater method in the Compton scattering region. The electron Compton profile for graphite is in good agreement with other conventional Compton profile measurements, as well as with theory, thus establishing the validity of the technique.

  7. Radiative interaction of a focused relativistic electron beam in energy-loss spectroscopy of nanoscopic platelets

    SciTech Connect

    Itskovsky, M. A.; Maniv, T.; Cohen, H.

    2008-07-15

    A quantum-mechanical scattering theory for relativistic, highly focused electron beams in the vacuum near nanoscopic platelets is presented, revealing an excitation mechanism due to the electron wave scattering from the platelet edges. Radiative electromagnetic excitations within the light cone are shown to arise, allowed by the breakdown of momentum conservation along the beam axis in the inelastic-scattering process. Calculated for metallic (silver and gold) and insulating (SiO{sub 2} and MgO) nanoplatelets, radiative features are revealed above the main surface-plasmon-polariton peak, and dramatic enhancements in the electron-energy-loss probability at gaps of the 'classical' spectra are found. The corresponding radiation should be detectable in the vacuum far-field zone, with e beams exploited as sensitive 'tip detectors' of electronically excited nanostructures.

  8. Signatures of Fano interferences in the electron energy loss spectroscopy and cathodoluminescence of symmetry-broken nanorod dimers.

    PubMed

    Bigelow, Nicholas W; Vaschillo, Alex; Camden, Jon P; Masiello, David J

    2013-05-28

    Through numerical simulation, we predict the existence of the Fano interference effect in the electron energy loss spectroscopy (EELS) and cathodoluminescence (CL) of symmetry-broken nanorod dimers that are heterogeneous in material composition and asymmetric in length. The differing selection rules of the electron probe in comparison to the photon of a plane wave allow for the simultaneous excitation of both optically bright and dark plasmons of each monomer unit, suggesting that Fano resonances will not arise in EELS and CL. Yet, interferences are manifested in the dimer's scattered near- and far-fields and are evident in EELS and CL due to the rapid π-phase offset in the polarizations between super-radiant and subradiant hybridized plasmon modes of the dimer as a function of the energy loss suffered by the impinging electron. Depending upon the location of the electron beam, we demonstrate the conditions under which Fano interferences will be present in both optical and electron spectroscopies (EELS and CL) as well as a new class of Fano interferences that are uniquely electron-driven and are absent in the optical response. Among other things, the knowledge gained from this work bears impact upon the design of some of the world's most sensitive sensors, which are currently based upon Fano resonances. PMID:23594310

  9. Examining Substrate-Induced Plasmon Mode Splitting and Localization in Truncated Silver Nanospheres with Electron Energy Loss Spectroscopy.

    PubMed

    Li, Guoliang; Cherqui, Charles; Wu, Yueying; Bigelow, Nicholas W; Simmons, Philip D; Rack, Philip D; Masiello, David J; Camden, Jon P

    2015-07-01

    Motivated by the need to study the size dependence of nanoparticle-substrate systems, we present a combined experimental and theoretical electron energy loss spectroscopy (EELS) study of the plasmonic spectrum of substrate-supported truncated silver nanospheres. This work spans the entire classical range of plasmonic behavior probing particles of 20-1000 nm in diameter, allowing us to map the evolution of localized surface plasmons into surface plasmon polaritons and study the size dependence of substrate-induced mode splitting. This work constitutes the first nanoscopic characterization and imaging of these effects in truncated nanospheres, setting the stage for the systematic study of plasmon-mediated energy transfer in nanoparticle-substrate systems. PMID:26266735

  10. Electronic structure of tin oxides by electron energy loss spectroscopy and real-space multiple scattering calculations

    SciTech Connect

    Moreno, M. S.; Egerton, R.F.; Rehr, J.J.; Midgley, P.A.

    2005-01-15

    The electronic structure of the tin oxides SnO and SnO{sub 2} is studied using the fine structure of the Sn-M{sub 4,5} and oxygen K-edges measured by electron energy loss spectroscopy (EELS). The experimental results are compared with real-space multiple scattering calculations. It is observed that both edges are overlapped. The calculations reveal that the observed fine structure is due largely to the oxygen states, and that it can be used to fingerprint each phase. The calculated densities of states are similar for both compounds and suggest a covalent nature. The structures appearing within the first 10 eV above the threshold arise from a covalent mixing of mainly O 2p and Sn 5s-p. For SnO the oxygen edge is satisfactorily reproduced. Discrepancies in the predicted energy position of the features in the EELS of SnO{sub 2} are briefly discussed.

  11. Band gap and defect states of MgO thin films investigated using reflection electron energy loss spectroscopy

    SciTech Connect

    Heo, Sung; Cho, Eunseog; Lee, Hyung-Ik; Park, Gyeong Su; Kang, Hee Jae; Nagatomi, T.; Choi, Pyungho; Choi, Byoung-Deog

    2015-07-15

    The band gap and defect states of MgO thin films were investigated by using reflection electron energy loss spectroscopy (REELS) and high-energy resolution REELS (HR-REELS). HR-REELS with a primary electron energy of 0.3 keV revealed that the surface F center (FS) energy was located at approximately 4.2 eV above the valence band maximum (VBM) and the surface band gap width (E{sub g}{sup S}) was approximately 6.3 eV. The bulk F center (F{sub B}) energy was located approximately 4.9 eV above the VBM and the bulk band gap width was about 7.8 eV, when measured by REELS with 3 keV primary electrons. From a first-principles calculation, we confirmed that the 4.2 eV and 4.9 eV peaks were F{sub S} and F{sub B}, induced by oxygen vacancies. We also experimentally demonstrated that the HR-REELS peak height increases with increasing number of oxygen vacancies. Finally, we calculated the secondary electron emission yields (γ) for various noble gases. He and Ne were not influenced by the defect states owing to their higher ionization energies, but Ar, Kr, and Xe exhibited a stronger dependence on the defect states owing to their small ionization energies.

  12. Localized magnetoplasmons in quantum dots: Scrutinizing the eligibility of FIR, Raman, and electron energy-loss spectroscopies

    NASA Astrophysics Data System (ADS)

    Kushwaha, M.

    We report on a one-component, quasi-zero dimensional, quantum plasma exposed to a parabolic potential and an applied magnetic field in the symmetric gauge. If the size of such a system as can be realized in the semiconducting quantum dots is on the order of the de-Broglie wavelength, the electronic and optical properties become highly tunable. Then the quantum size effects challenge the observation of many-particle phenomena such as the magneto-optical absorption, Raman intensity, and electron-energy-loss spectrum. An exact analytical solution of the problem leads us to infer that these many-particle phenomena are, in fact, dictated by the generalized Kohn's theorem in the long-wavelength limit. Maneuvering the confinement and/or the magnetic field furnishes the resonance energy capable of being explored with the FIR, Raman, or electron-energy-loss spectroscopy. This implies that either of these probes should be competent in observing the localized magnetoplasmons in the system. A deeper insight into the physics of quantum dots is paving the way for their implementation in such diverse fields as quantum computing and medical imaging1. 1. M.S. Kushwaha, Unpublished.

  13. Verifying the Presence of Low Levels of Neptunium in a Uranium Matrix with Electron Energy-Loss Spectroscopy

    SciTech Connect

    Buck, Edgar C.; Douglas, Matthew; Wittman, Richard S.

    2010-01-01

    This paper examines the problems associated with the analysis of low levels of neptunium (Np) in a uranium (U) matrix with electron energy-loss spectroscopy (EELS) on the transmission electron microscope (TEM). The detection of Np in a matrix of uranium (U) can be impeded by the occurrence of a plural scattering event from U (U-M5 + U-O4,5) that results in severe overlap on the Np-M5 edge at 3665 eV. Low levels (1600 - 6300 ppm) of Np can be detected in U solids by confirming the energy gap between the Np-M5 and Np-M4 edges is at 184 eV and showing that the M4/M5 ratio for the Np is smaller than that for U. The Richardson-Lucy deconvolution method was applied to energy-loss spectral images and was shown to increase the signal to noise. This method also improves the limits of detection for Np in a U matrix.

  14. Oxidation study by Auger electron spectroscopy and electron energy-loss spectroscopy of GaSb(001) surfaces grown by molecular-beam epitaxy

    SciTech Connect

    Raisin, C.; Da Silva, F.W.O.; Lassabatere, L. , Place Eugene Bataillon, 34095 Montpellier-Cedex 5, France )

    1990-01-01

    GaSb (001) surfaces were prepared by molecular-beam epitaxy. Auger electron spectroscopy (AES) and electron energy-loss spectroscopy (EELS) are reported for clean surfaces exposed to oxygen, and during the process the ionization gauge of the vacuum system is turned on. Successive stages of chemisorption can be distinguished. For oxygen coverage up to 0.5 monolayer, the surface states are saturated by bonding of the oxygen with Ga and Sb atoms. Sb atoms desorb causing significant Sb depletion in the first layer. Larger exposures further increase the coverage and induce, in the EELS spectra, losses related to O(2{ital p}) and O(2{ital s}) atomic states and new plasmon excitations. In the AES spectra the shift of Auger emission lines which are characteristic of Sb and Ga oxide forms appear; at coverages of about one monolayer back bonds break forming Sb{sub 2}O{sub 3} and Ga{sub 2}O{sub 3}. Further exposures to oxygen result in thicker oxide layers of Ga and Sb.

  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. Investigation of the oxidation states of Cu additive in colored borosilicate glasses by electron energy loss spectroscopy

    NASA Astrophysics Data System (ADS)

    Yang, Guang; Cheng, Shaodong; Li, Chao; Zhong, Jiasong; Ma, Chuansheng; Wang, Zhao; Xiang, Weidong

    2014-12-01

    Three optically transparent colorful (red, green, and blue) glasses were synthesized by the sol-gel method. Nano-sized precipitates were found in scanning electron microscopy images. The precipitates were analyzed by transmission electron microscopy (TEM) and high resolution TEM. The measured lattice parameters of these precipitates were found to fit the metallic copper in red glass but deviate from single valenced Cu oxides in green and blue glasses. The chemistry of these nano-sized particles was confirmed by electron energy loss spectroscopy (EELS). By fitting the EELS spectra obtained from the precipitates with the linear combination of reference spectra from Cu reference compounds, the oxidation states of Cu in the precipitates have been derived. First principle calculations suggested that the Cu nano-particles, which are in the similar oxidation states as our measurement, would show green color in the visible light range.

  17. Full Three-Dimensonal Reconstruction of the Dyadic Green Tensor from Electron Energy Loss Spectroscopy of Plasmonic Nanoparticles

    PubMed Central

    2015-01-01

    Electron energy loss spectroscopy (EELS) has emerged as a powerful tool for the investigation of plasmonic nanoparticles, but the interpretation of EELS results in terms of optical quantities, such as the photonic local density of states, remains challenging. Recent work has demonstrated that, under restrictive assumptions, including the applicability of the quasistatic approximation and a plasmonic response governed by a single mode, one can rephrase EELS as a tomography scheme for the reconstruction of plasmonic eigenmodes. In this paper we lift these restrictions by formulating EELS as an inverse problem and show that the complete dyadic Green tensor can be reconstructed for plasmonic particles of arbitrary shape. The key steps underlying our approach are a generic singular value decomposition of the dyadic Green tensor and a compressed sensing optimization for the determination of the expansion coefficients. We demonstrate the applicability of our scheme for prototypical nanorod, bowtie, and cube geometries. PMID:26523284

  18. Investigation of the oxidation states of Cu additive in colored borosilicate glasses by electron energy loss spectroscopy

    SciTech Connect

    Yang, Guang Cheng, Shaodong; Li, Chao; Ma, Chuansheng; Zhong, Jiasong; Xiang, Weidong; Wang, Zhao

    2014-12-14

    Three optically transparent colorful (red, green, and blue) glasses were synthesized by the sol-gel method. Nano-sized precipitates were found in scanning electron microscopy images. The precipitates were analyzed by transmission electron microscopy (TEM) and high resolution TEM. The measured lattice parameters of these precipitates were found to fit the metallic copper in red glass but deviate from single valenced Cu oxides in green and blue glasses. The chemistry of these nano-sized particles was confirmed by electron energy loss spectroscopy (EELS). By fitting the EELS spectra obtained from the precipitates with the linear combination of reference spectra from Cu reference compounds, the oxidation states of Cu in the precipitates have been derived. First principle calculations suggested that the Cu nano-particles, which are in the similar oxidation states as our measurement, would show green color in the visible light range.

  19. Distinguishing cubic and hexagonal phases within InGaN/GaN microstructures using electron energy loss spectroscopy

    PubMed Central

    CHERNS, D; ALBERT, S.; BENGOECHEA‐ENCABO, A.; ANGEL SANCHEZ, M.; CALLEJA, E.; SCHIMPKE, T.; STRASSBURG, M.

    2015-01-01

    Summary 3D InGaN/GaN microstructures grown by metal organic vapor phase epitaxy (MOVPE) and molecular beam epitaxy (MBE) have been extensively studied using a range of electron microscopy techniques. The growth of material by MBE has led to the growth of cubic GaN material. The changes in these crystal phases has been investigated by Electron Energy Loss Spectroscopy, where the variations in the fine structure of the N K‐edge shows a clear difference allowing the mapping of the phases to take place. GaN layers grown for light emitting devices sometimes have cubic inclusions in the normally hexagonal wurtzite structures, which can influence the device electronic properties. Differences in the fine structure of the N K‐edge between cubic and hexagonal material in electron energy loss spectra are used to map cubic and hexagonal regions in a GaN/InGaN microcolumnar device. The method of mapping is explained, and the factors limiting spatial resolution are discussed. PMID:26366483

  20. Distinguishing cubic and hexagonal phases within InGaN/GaN microstructures using electron energy loss spectroscopy.

    PubMed

    Griffiths, I J; Cherns, D; Albert, S; Bengoechea-Encabo, A; Angel Sanchez, M; Calleja, E; Schimpke, T; Strassburg, M

    2016-05-01

    3D InGaN/GaN microstructures grown by metal organic vapor phase epitaxy (MOVPE) and molecular beam epitaxy (MBE) have been extensively studied using a range of electron microscopy techniques. The growth of material by MBE has led to the growth of cubic GaN material. The changes in these crystal phases has been investigated by Electron Energy Loss Spectroscopy, where the variations in the fine structure of the N K-edge shows a clear difference allowing the mapping of the phases to take place. GaN layers grown for light emitting devices sometimes have cubic inclusions in the normally hexagonal wurtzite structures, which can influence the device electronic properties. Differences in the fine structure of the N K-edge between cubic and hexagonal material in electron energy loss spectra are used to map cubic and hexagonal regions in a GaN/InGaN microcolumnar device. The method of mapping is explained, and the factors limiting spatial resolution are discussed. PMID:26366483

  1. The beta-SiC(100) surface studied by low energy electron diffraction, Auger electron spectroscopy, and electron energy loss spectra

    NASA Technical Reports Server (NTRS)

    Dayan, M.

    1986-01-01

    The beta-SiC(100) surface has been studied by low energy electron diffraction, Auger electron spectroscopy, high resolution electron energy loss spectra (HREELS), and core level excitation EELS. Two new Si-terminated phases have been discovered, one with (3 x 2) symmetry, and the other with (2 x 1) symmetry. Models are presented to describe these phases. New results, for the C-rich surface, are presented and discussed. In addition, core level excitation EELS results are given and compared with theory.

  2. Using Plasmon Peaks in Electron Energy-Loss Spectroscopy to Determine the Physical and Mechanical Properties of Nanoscale Materials

    SciTech Connect

    Howe, James M.

    2013-05-09

    In this program, we developed new theoretical and experimental insights into understanding the relationships among fundamental universality and scaling phenomena, the solid-state physical and mechanical properties of materials, and the volume plasmon energy as measured by electron energy-loss spectroscopy (EELS). Particular achievements in these areas are summarized as follows: (i) Using a previously proposed physical model based on the universal binding-energy relation (UBER), we established close phenomenological connections regarding the influence of the valence electrons in materials on the longitudinal plasma oscillations (plasmons) and various solid-state properties such as the optical constants (including absorption and dispersion), elastic constants, cohesive energy, etc. (ii) We found that carbon materials, e.g., diamond, graphite, diamond-like carbons, hydrogenated and amorphous carbon films, exhibit strong correlations in density vs. Ep (or maximum of the volume plasmon peak) and density vs. hardness, both from available experimental data and ab initio DFT calculations. This allowed us to derive a three-dimensional relationship between hardness and the plasmon energy, that can be used to determine experimentally both hardness and density of carbon materials based on measurements of the plasmon peak position. (iii) As major experimental accomplishments, we demonstrated the possibility of in-situ monitoring of changes in the physical properties of materials with conditions, e.g., temperature, and we also applied a new plasmon ratio-imaging technique to map multiple physical properties of materials, such as the elastic moduli, cohesive energy and bonding electron density, with a sub-nanometer lateral resolution. This presents new capability for understanding material behavior. (iv) Lastly, we demonstrated a new physical phenomenon - electron-beam trapping, or electron tweezers - of a solid metal nanoparticle inside a liquid metal. This phenomenon is

  3. Comprehensive studies of the electronic structure of pristine and potassium doped chrysene investigated by electron energy-loss spectroscopy

    NASA Astrophysics Data System (ADS)

    Roth, Friedrich; Mahns, Benjamin; Schönfelder, Ronny; Hampel, Silke; Nohr, Markus; Büchner, Bernd; Knupfer, Martin

    2012-09-01

    We have performed electron energy-loss spectroscopy studies in order to investigate the electronic properties of chrysene molecular solids. The valence band electronic excitation spectra and the C 1s core level excitations have been measured for pristine and potassium doped chrysene. The core level studies show a fine structure which signals the presence of four close lying conduction bands close to the Fermi level. Upon potassium doping, these bands are filled with electrons, and we have reached a doping level of about K2.7chrysene. Furthermore, undoped chrysene is characterized by an optical gap of about 3.3 eV and five, relatively weak, excitonic features following the excitation onset. Doping induces major changes in the electronic excitation spectra, with a new, prominent low energy excitation at about 1.3 eV. The results of a Kramers-Kronig analysis indicate that this new feature can be assigned to a charge carrier plasmon in the doped material, and momentum dependent studies reveal a negative plasmon dispersion.

  4. Optical Dark-Field and Electron Energy Loss Imaging and Spectroscopy of Symmetry-Forbidden Modes in Loaded Nanogap Antennas.

    PubMed

    Brintlinger, Todd; Herzing, Andrew A; Long, James P; Vurgaftman, Igor; Stroud, Rhonda; Simpkins, B S

    2015-06-23

    We have produced large numbers of hybrid metal-semiconductor nanogap antennas using a scalable electrochemical approach and systematically characterized the spectral and spatial character of their plasmonic modes with optical dark-field scattering, electron energy loss spectroscopy with principal component analysis, and full wave simulations. The coordination of these techniques reveal that these nanostructures support degenerate transverse modes which split due to substrate interactions, a longitudinal mode which scales with antenna length, and a symmetry-forbidden gap-localized transverse mode. This gap-localized transverse mode arises from mode splitting of transverse resonances supported on both antenna arms and is confined to the gap load enabling (i) delivery of substantial energy to the gap material and (ii) the possibility of tuning the antenna resonance via active modulation of the gap material's optical properties. The resonant position of this symmetry-forbidden mode is sensitive to gap size, dielectric strength of the gap material, and is highly suppressed in air-gapped structures which may explain its absence from the literature to date. Understanding the complex modal structure supported on hybrid nanosystems is necessary to enable the multifunctional components many seek. PMID:25961937

  5. Investigation of the dispersion and the effective masses of excitons in bulk 2 H -MoS2 using transition electron energy-loss spectroscopy

    NASA Astrophysics Data System (ADS)

    Habenicht, Carsten; Knupfer, Martin; Büchner, Bernd

    2015-06-01

    We have investigated the electronic excitations in bulk 2 H -MoS2 using electron energy-loss spectroscopy. The electron energy-loss spectra in the Γ M and Γ K directions were measured for various momentum transfer values. The results allow the identification of the A1 and B1 exciton peaks and in particular their energy-momentum dispersion. The dispersions exhibit approximately quadratic upward trends and slight anisotropies in the Γ M and Γ K directions. The fitted energy-momentum transfer functions allow the estimation of the effective masses of the excitons which are in close proximity to predicted values.

  6. Electron energy-loss spectroscopy analysis of HfO2 dielectric films on strained and relaxed SiGe /Si substrates

    NASA Astrophysics Data System (ADS)

    Jang, Jiyoung; Park, Tae Joo; Kwon, Ji-Hwan; Jang, Jae Hyuck; Hwang, Cheol Seong; Kim, Miyoung

    2008-06-01

    In this investigation, HfO2 thin films were deposited on strained and strain-relaxed epitaxial-SiGe /Si substrates, and subsequently subjected to annealing. Electron energy-loss spectroscopy analysis was used to investigate the electronic structure and composition of the film as well as the interfacial layer (IL). While the energy-loss function of the dielectric films revealed predominant Si diffusion in the strained substrates, post deposition annealing (PDA) significantly influenced the diffusion and altered the local composition of the IL in strain-relaxed substrates. Analysis of electronic structures revealed the origin of significant loss of Ge atoms at the IL during PDA.

  7. Atomic scale structure and chemistry of interfaces by Z-contrast imaging and electron energy loss spectroscopy in the STEM

    SciTech Connect

    McGibbon, M.M.; Browning, N.D.; Chisholm, M.F.; Pennycook, S.J.

    1993-12-01

    The macroscopic properties of many materials are controlled by the structure and chemistry at the grain boundaries. A basic understanding of the structure-property relationship requires a technique which probes both composition and chemical bonding on an atomic scale. The high-resolution Z-contrast imaging technique in the scanning transmission electron microscope (STEM) forms an incoherent image in which changes in atomic structure and composition can be interpreted intuitively. This direct image allows the electron probe to be positioned over individual atomic columns for parallel detection electron energy loss spectroscopy (PEELS) at a spatial resolution approaching 0.22nm. The bonding information which can be obtained from the fine structure within the PEELS edges can then be used in conjunction with the Z-contrast images to determine the structure at the grain boundary. In this paper we present 3 examples of correlations between the structural, chemical and electronic properties at materials interfaces in metal-semiconductor systems, superconducting and ferroelectric materials.

  8. High-carbon concentrations at the silicon dioxide-silicon carbide interface identified by electron energy loss spectroscopy

    NASA Astrophysics Data System (ADS)

    Chang, K. C.; Nuhfer, N. T.; Porter, L. M.; Wahab, Q.

    2000-10-01

    High carbon concentrations at distinct regions at thermally-grown SiO2/6H-SiC(0001) interfaces have been detected by electron energy loss spectroscopy (EELS). The thickness of these C-rich regions is estimated to be 10-15 Å. The oxides were grown on n-type 6H-SiC at 1100 °C in a wet O2 ambient for 4 h immediately after cleaning the substrates with the complete RCA process. In contrast, C-rich regions were not detected from EELS analyses of thermally grown SiO2/Si interfaces nor of chemical vapor deposition deposited SiO2/SiC interfaces. Silicon-rich layers within the SiC substrate adjacent to the thermally grown SiO2/SiC interface were also evident. The interface state density Dit in metal-oxide-SiC diodes (with thermally grown SiO2) was approximately 9×1011cm-2 eV-1 at E-Ev=2.0 eV, which compares well with reported values for SiC metal-oxide-semiconductor (MOS) diodes that have not received a postoxidation anneal. The C-rich regions and the change in SiC stoichiometry may be associated with the higher than desirable Dit's and the low channel mobilities in SiC-based MOS field effect transistors.

  9. Hydrogenated graphene on Ir(111): A high-resolution electron energy loss spectroscopy study of the vibrational spectrum

    NASA Astrophysics Data System (ADS)

    Kyhl, Line; Balog, Richard; Angot, Thierry; Hornekær, Liv; Bisson, Régis

    2016-03-01

    Hydrogen atom adsorption on high-quality graphene on Ir(111) [gr/Ir(111)] is investigated using high-resolution electron energy loss spectroscopy. The evolution of the vibrational spectrum, up to 400 meV, of gr/Ir(111) upon increasing hydrogen atom exposures is measured. The two dominant binding configurations of atomic hydrogen are identified as (1) graphanelike hydrogen clusters on the parts of the graphene more strongly interacting with the Ir(111) surface and (2) dimers bound more weakly to the freestanding parts of the graphene. The graphanelike surface structures lead to increased corrugation of the graphene sheet, yielding graphane-related phonon components. Additionally, a recent theoretical prediction of the existence of a bending character for a LO/TO graphane chair phonon mode is experimentally verified. No clear evidence was found for hydrogen bound on both sides of a high-quality graphene sheet and phonon features strongly suggest interactions between graphanelike hydrogen clusters and Ir atoms in the substrate.

  10. Electron Energy-Loss Spectroscopy (EELS)Calculation in Finite-Difference Time-Domain (FDTD) Package: EELS-FDTD

    NASA Astrophysics Data System (ADS)

    Large, Nicolas; Cao, Yang; Manjavacas, Alejandro; Nordlander, Peter

    2015-03-01

    Electron energy-loss spectroscopy (EELS) is a unique tool that is extensively used to investigate the plasmonic response of metallic nanostructures since the early works in the '50s. To be able to interpret and theoretically investigate EELS results, a myriad of different numerical techniques have been developed for EELS simulations (BEM, DDA, FEM, GDTD, Green dyadic functions). Although these techniques are able to predict and reproduce experimental results, they possess significant drawbacks and are often limited to highly symmetrical geometries, non-penetrating trajectories, small nanostructures, and free standing nanostructures. We present here a novel approach for EELS calculations using the Finite-difference time-domain (FDTD) method: EELS-FDTD. We benchmark our approach by direct comparison with results from the well-established boundary element method (BEM) and published experimental results. In particular, we compute EELS spectra for spherical nanoparticles, nanoparticle dimers, nanodisks supported by various substrates, and gold bowtie antennas on a silicon nitride substrate. Our EELS-FDTD implementation can be easily extended to more complex geometries and configurations and can be directly implemented within other numerical methods. Work funded by the Welch Foundation (C-1222, L-C-004), and the NSF (CNS-0821727, OCI-0959097).

  11. Electron-energy-loss spectroscopy and X-ray absorption spectroscopy as complementary probes for complex f-electron metals: cerium and plutonium

    NASA Astrophysics Data System (ADS)

    Moore, K. T.; Wall, M. A.; Schwartz, A. J.; Chung, B. W.; Morton, S. A.; Tobin, J. G.; Lazar, S.; Tichelaar, F. D.; Zandbergen, H. W.; Söderlind, P.; van der Laan, G.

    2004-04-01

    In this paper, we demonstrate the power of electron-energy-loss spectroscopy (EELS) in a transmission electron microscope by investigating the electron structure of two f-electron metals: Ce and Pu. It is shown that EELS in a transmission electron microscope may be used to circumvent the difficulty of producing single-phase or single-crystal samples owing to its high spatial resolution, and that diffraction patterns and images can be acquired, providing unambiguous phase determination when acquiring spectra. EELS results are supported by synchrotron-radiation-based X-ray absorption, multielectron atomic spectral simulations, and local density approximation calculations based on density-functional theory with the generalized gradient approximation. For Ce, it is shown that changes in {111} stacking sequences can drive substantial modifications in the electronic structure of close-packed phases of Ce that have similar atomic volumes, contrary to previous assumptions in literature. For Pu, it is shown that Russell-Saunders (L-S) coupling fails for the 5f states and that either a j-j or an intermediate scheme must be used for the actinides because of the considerable spin-orbit interaction in the 5f states. We present a model showing how the 5f states behave along the light actinide series.

  12. Study of semiconductor valence plasmon line shapes via electron energy-loss spectroscopy in the transmission electron microscope

    SciTech Connect

    Kundmann, M.K.

    1988-11-01

    Electron energy-loss spectra of the semiconductors Si, AlAs, GaAs, InAs, InP, and Ge are examined in detail in the regime of outer-shell and plasmon energy losses (0--100eV). Particular emphasis is placed on modeling and analyzing the shapes of the bulk valence plasmon lines. A line shape model based on early work by Froehlich is derived and compared to single-scattering probability distributions extracted from the measured spectra. Model and data are found to be in excellent agreement, thus pointing the way to systematic characterization of the plasmon component of EELS spectra. The model is applied to three separate investigations. 82 refs.

  13. Energy losses in switches

    SciTech Connect

    Martin, T.H.; Seamen, J.F.; Jobe, D.O.

    1993-07-01

    The authors experiments show energy losses between 2 and 10 times that of the resistive time predictions. The experiments used hydrogen, helium, air, nitrogen, SF{sub 6} polyethylene, and water for the switching dielectric. Previously underestimated switch losses have caused over predicting the accelerator outputs. Accurate estimation of these losses is now necessary for new high-efficiency pulsed power devices where the switching losses constitute the major portion of the total energy loss. They found that the switch energy losses scale as (V{sub peak}I{sub peak}){sup 1.1846}. When using this scaling, the energy losses in any of the tested dielectrics are almost the same. This relationship is valid for several orders of magnitude and suggested a theoretical basis for these results. Currents up to .65 MA, with voltages to 3 MV were applied to various gaps during these experiments. The authors data and the developed theory indicates that the switch power loss continues for a much longer time than the resistive time, with peak power loss generally occurring at peak current in a ranging discharge instead of the early current time. All of the experiments were circuit code modeled after developing a new switch loss version based on the theory. The circuit code predicts switch energy loss and peak currents as a function of time. During analysis of the data they noticed slight constant offsets between the theory and data that depended on the dielectric. They modified the plasma conductivity for each tested dielectric to lessen this offset.

  14. The effectiveness of electron holography, microscopy, and energy-loss spectroscopy in characterizing thin silicon oxide-nitride-oxide structures

    NASA Astrophysics Data System (ADS)

    Waytena, G. L.; Hren, J.; Rez, P.

    1993-02-01

    High-resolution transmission electron microscopy, electron holography, and high-spatial- resolution (19 Å) computer-controlled parallel electron-energy-loss spectrometry (PEELS) were used to probe the structure of and chemical profile across two thin silicon oxide-nitride-oxide layered structures of nominal widths of 10 Å-50 Å-10 Å and 30 Å-50 Å-30 Å. It was found that the individual layers of the stacked structures could be clearly imaged using electron holography, but not with electron microscopy due to the behavior of the microscope transfer function and the shape of the potential profile of the structure. Holography revealed that the layers of the 10 Å-50 Å-10 Å system were in fact 14 Å-28 Å-18 ż5 Å, and the oxide layer in contact with the substrate (first oxide layer) was discontinuous. PEELS showed that the second oxide layer contained nitrogen, and the nitride layer had a silicon-to-nitrogen concentration ratio of 1.0±0.1. The 30 Å-50 Å-30 Å system was in fact 30 Å-20 Å-40 Å-15 ż5 Å. The second oxide layer was SiO1.6±0.2, and nitrogen was found near the film surface which made the structure appear to be four layers. These results show the power of holography in characterizing thin, light-element, amorphous layers and the importance of computer-controlled parallel energy-loss line scans for obtaining analytical information at the highest spatial resolution with minimum dose.

  15. Determination of electronic properties of nanostructures using reflection electron energy loss spectroscopy: Nano-metalized polymer as case study

    NASA Astrophysics Data System (ADS)

    Deris, Jamileh; Hajati, Shaaker; Tougaard, Sven; Zaporojtchenko, Vladimir

    2016-07-01

    In this work, Au was deposited with nominal effective thickness of 0.8 nm on polystyrene (PS) at room temperature. According to previous study, using XPS peak shape analysis [S. Hajati, V. Zaporojtchenko, F. Faupel, S. Tougaard, Surf. Sci. 601 (2007) 3261-3267], Au nanoparticles (Au-NPs) of sizes 5.5 nm were formed corresponding to such effective thickness (0.8 nm). Then the sample was annealed to 200 °C, which is far above the glass transition of PS. At this temperature, the Au-NPs were diffused within the depth 0.5 nm-6.5 nm as found using nondestructive XPS peak shape analysis. Electrons with primary energy 500 eV were used because the electronic properties will then be probed in utmost surface (∼1 IMFP range of depths that is 1.8 nm for PS). By using QUEELS software, theoretical and experimental electron inelastic cross section, energy loss function, electron inelastic mean free path and surface excitation parameters were obtained for the sample. The information obtained here, does not rely on any previously known information on the sample. This means that the method, applied here, is suitable for the determination of the electronic properties of new and unknown composite nanostructures.

  16. Trichroism in energy-loss near-edge structure spectroscopy: Polarization dependence of near-edge fine structures

    SciTech Connect

    Le Bosse, Jean-Claude; Epicier, Thierry; Chermette, Henry

    2007-08-15

    The goal of this paper is to relate the current of inelastically scattered electrons collected in a transmission electron microscope (TEM) to the double differential electron energy-loss cross section. Up to now, this relationship, which depends on the point symmetry around the probed atom site, has been essentially studied in a situation called dichroism. This situation can be encountered when a principal threefold, fourfold, or sixfold rotation axis through the probed atom site exists. The electron energy-loss cross section is then a linear combination of longitudinal and transversal cross sections, and the weights of these components are cos{sup 2} {theta}{sub q} and sin{sup 2} {theta}{sub q}, where {theta}{sub q} is the angle between the scattering wave vector q and the principal rotation axis. The first aim of this paper is to find the dependence on q of the cross section in all other cases, that is to say, when the symmetry around the probed atom site is described with one of the eight low symmetry point groups C{sub 1}, S{sub 2}, C{sub 1h}, C{sub 2}, C{sub 2h}, C{sub 2v}, D{sub 2}, and D{sub 2h}. In these eight cases of low symmetry, three distinct situations called trichroism can be distinguished. In these situations, the cross section is expressed in terms of the cross sections obtained for six, four, or three particular orientations of the scattering wave vector. The second aim of this paper is to provide an expression of the inelastically scattered electron current collected in a TEM for these three situations of trichroism. This current is expressed in terms of experimental parameters, such as the incident beam convergence, the collector acceptance, the electron beam kinetic energy, and the sample orientation. As in the case of dichroism, magic conditions can be found, for which the collected current becomes independent of the single-crystal sample orientation. The case of the C K edge in the nonstoichiometric V{sub 6}C{sub 5} metallic carbide with a

  17. Free electrons and ionic liquids: study of excited states by means of electron-energy loss spectroscopy and the density functional theory multireference configuration interaction method.

    PubMed

    Regeta, Khrystyna; Bannwarth, Christoph; Grimme, Stefan; Allan, Michael

    2015-06-28

    The technique of low energy (0-30 eV) electron impact spectroscopy, originally developed for gas phase molecules, is applied to room temperature ionic liquids (IL). Electron energy loss (EEL) spectra recorded near threshold, by collecting 0-2 eV electrons, are largely continuous, assigned to excitation of a quasi-continuum of high overtones and combination vibrations of low-frequency modes. EEL spectra recorded by collecting 10 eV electrons show predominantly discrete vibrational and electronic bands. The vibrational energy-loss spectra correspond well to IR spectra except for a broadening (∼0.04 eV) caused by the liquid surroundings, and enhanced overtone activity indicating a contribution from resonant excitation mechanism. The spectra of four representative ILs were recorded in the energy range of electronic excitations and compared to density functional theory multireference configuration interaction (DFT/MRCI) calculations, with good agreement. The spectra up to about 8 eV are dominated by π-π* transitions of the aromatic cations. The lowest bands were identified as triplet states. The spectral region 2-8 eV was empty in the case of a cation without π orbitals. The EEL spectrum of a saturated solution of methylene green in an IL band showed the methylene green EEL band at 2 eV, indicating that ILs may be used as a host to study nonvolatile compounds by this technique in the future. PMID:26018044

  18. Observability of localized magnetoplasmons in quantum dots: Scrutinizing the eligibility of far-infrared, Raman, and electron-energy-loss spectroscopies

    NASA Astrophysics Data System (ADS)

    Kushwaha, Manvir S.

    2016-03-01

    We investigate a one-component, quasi-zero dimensional, quantum plasma exposed to a parabolic potential and an applied magnetic field in the symmetric gauge. If the size of such a system as can be realized in the semiconducting quantum dots is on the order of the de-Broglie wavelength, the electronic and optical properties become highly tunable. Then the quantum size effects challenge the observation of many-particle phenomena such as the magneto-optical absorption, Raman intensity, and electron energy-loss spectrum. An exact analytical solution of the problem leads us to infer that these many-particle phenomena are, in fact, dictated by the generalized Kohn's theorem (GKT) in the long-wavelength limit. Maneuvering the confinement and/or the magnetic field furnishes the resonance energies capable of being explored with the FIR, Raman, and/or electron-energy-loss spectroscopy. This implies that either of these probes is competent in observing the localized magnetoplasmons in the system. As an application of the rigorous analytical diagnosis of the system, we have presented various pertinent single-particle, such as Fock-Darwin spectrum, Fermi energy, zigzag excitation spectrum, and magneto-optical transitions, and the many-particle phenomena, such as magneto-optical absorption, Raman intensity, and electron energy-loss probability. In the latter, the energy position of the resonance peaks is observed to be independent of the electron-electron interactions and hence of the number of electrons in the quantum dot in compliance with the GKT. It is found that both confinement potential and magnetic field play a decisive role in influencing the aforementioned many-particle phenomena. Specifically, increasing (decreasing) the strength of the confining potential is found to be analogous to shrinking (expanding) the size of the quantum dots and results into a blue (red) shift in the respective spectra. Intensifying the magnetic field has two-fold effects in the resonance

  19. Band-Gap Widening at the Cu(In,Ga)(S,Se)2 Surface: A Novel Determination Approach Using Reflection Electron Energy Loss Spectroscopy.

    PubMed

    Hauschild, Dirk; Handick, Evelyn; Göhl-Gusenleitner, Sina; Meyer, Frank; Schwab, Holger; Benkert, Andreas; Pohlner, Stephan; Palm, Jörg; Tougaard, Sven; Heske, Clemens; Weinhardt, Lothar; Reinert, Friedrich

    2016-08-17

    Using reflection electron energy loss spectroscopy (REELS), we have investigated the optical properties at the surface of a chalcopyrite-based Cu(In,Ga)(S,Se)2 (CIGSSe) thin-film solar cell absorber, as well as an indium sulfide (InxSy) buffer layer before and after annealing. By fitting the characteristic inelastic scattering cross-section λK(E) to cross sections evaluated by the QUEELS-ε(k,ω)-REELS software package, we determine the surface dielectric function and optical properties of these samples. A comparison of the optical values at the surface of the InxSy film with bulk ellipsometry measurements indicates a good agreement between bulk- and surface-related optical properties. In contrast, the properties of the CIGSSe surface differ significantly from the bulk. In particular, a larger (surface) band gap than for bulk-sensitive measurements is observed, providing a complementary and independent confirmation of earlier photoelectron spectroscopy results. Finally, we derive the inelastic mean free path λ for electrons in InxSy, annealed InxSy, and CIGSSe at a kinetic energy of 1000 eV. PMID:27463021

  20. Microstructure of highly strained BiFeO3 thin films: Transmission electron microscopy and electron-energy loss spectroscopy studies

    NASA Astrophysics Data System (ADS)

    Heon Kim, Young; Bhatnagar, Akash; Pippel, Eckhard; Alexe, Marin; Hesse, Dietrich

    2014-01-01

    Microstructure and electronic structure of highly strained bismuth ferrite (BiFeO3) thin films grown on lanthanum aluminate substrates are studied using high-resolution transmission and scanning transmission electron microscopies and electron energy loss spectroscopy (EELS). Monoclinic and tetragonal phases were observed in films grown at different temperatures, and a mix of both phases was detected in a film grown at intermediate temperature. In this film, a smooth transition of the microstructure was found between the monoclinic and the tetragonal phases. A considerable increase in the c-axis parameters was observed in both phases compared with the rhombohedral bulk phase. The off-center displacement of iron (Fe) ions was increased in the monoclinic phase as compared with the tetragonal phase. EEL spectra show different electronic structures in the monoclinic and the tetragonal phases. These experimental observations are well consistent with the results of theoretical first-principle calculations performed.

  1. Microstructure of highly strained BiFeO{sub 3} thin films: Transmission electron microscopy and electron-energy loss spectroscopy studies

    SciTech Connect

    Heon Kim, Young; Bhatnagar, Akash; Pippel, Eckhard; Hesse, Dietrich; Alexe, Marin

    2014-01-28

    Microstructure and electronic structure of highly strained bismuth ferrite (BiFeO{sub 3}) thin films grown on lanthanum aluminate substrates are studied using high-resolution transmission and scanning transmission electron microscopies and electron energy loss spectroscopy (EELS). Monoclinic and tetragonal phases were observed in films grown at different temperatures, and a mix of both phases was detected in a film grown at intermediate temperature. In this film, a smooth transition of the microstructure was found between the monoclinic and the tetragonal phases. A considerable increase in the c-axis parameters was observed in both phases compared with the rhombohedral bulk phase. The off-center displacement of iron (Fe) ions was increased in the monoclinic phase as compared with the tetragonal phase. EEL spectra show different electronic structures in the monoclinic and the tetragonal phases. These experimental observations are well consistent with the results of theoretical first-principle calculations performed.

  2. High-resolution electron-energy-loss spectroscopy and photoelectron-diffraction studies of the geometric structure of adsorbates on single-crystal metal surfaces

    SciTech Connect

    Rosenblatt, D.H.

    1982-11-01

    Two techniques which have made important contributions to the understanding of surface phenomena are high resolution electron energy loss spectroscopy (EELS) and photoelectron diffraction (PD). EELS is capable of directly measuring the vibrational modes of clean and adsorbate covered metal surfaces. In this work, the design, construction, and performance of a new EELS spectrometer are described. These results are discussed in terms of possible structures of the O-Cu(001) system. Recommendations for improvements in this EELS spectrometer and guidelines for future spectrometers are given. PD experiments provide accurate quantitative information about the geometry of atoms and molecules adsorbed on metal surfaces. The technique has advantages when used to study disordered overlayers, molecular overlayers, multiple site systems, and adsorbates which are weak electron scatterers. Four experiments were carried out which exploit these advantages.

  3. Electron-energy-loss spectroscopy of YBa sub 2 Cu sub 3 minus x Fe sub x O sub 7 minus y superconductors

    SciTech Connect

    Vaishnava, P.P.; Taylor, C.A. II ); Foiles, C.L. )

    1990-03-01

    YBa{sub 2}Cu{sub 3{minus}{ital x}}Fe{sub {ital x}}O{sub 7{minus}{ital y}} ({ital x}=0.0, 0.05, 0.1) compounds have been studied using energy-dispersive x-ray (EDX) and electron-energy-loss spectroscopy (EELS). X-ray diffraction data indicated the formation of structurally known superconducting compounds. Transition temperatures, as measured by a Faraday balance, showed a decrease as the iron concentration was increased. Using the spot mode in an analytical electron microscope, the EDX and EELS data were obtained for identifiable, well-defined small regions of the superconducting particles. EDX spectra have been used to analyze different components and phases present in the samples. Detailed EELS data for the O 1{ital s} excitation have been obtained, and a peak in the pre-edge continuum has been observed in all the samples. The intensity and the nature of this peak are found to depend upon the iron concentration. The results of this investigation suggest structural disorder and orthorhombic-to-tetragonal transition as major reasons for the decrease in transition temperature for the iron-doped superconductors.

  4. Mass loss from red giants - Infrared spectroscopy

    NASA Technical Reports Server (NTRS)

    Wannier, P. G.

    1985-01-01

    A discussion is presented of IR spectroscopy, particularly high-resolution spectroscopy in the approximately 1-20 micron band, as it impacts the study of circumstellar envelopes. The molecular bands within this region contain an enormous amount of information, especially when observed with sufficient resolution to obtain kinematic information. In a single spectrum, it is possible to resolve lines from up to 50 different rotational/vibrational levels of a given molecule and to detect several different isotopic variants. When high resolution techniques are combined with mapping techniques and/or time sequence observations of variable stars, the resulting information can paint a very detailed picture of the mass-loss phenomenon. To date, near-IR observations have been made of 20 molecular species. CO is the most widely observed molecule and useful information has been gleaned from the observed rotational excitation, kinematics, time variability and spatial structure of its lines. Examples of different observing techniques are discussed in the following sections.

  5. Microstructure and Electron Energy-Loss Spectroscopy Analysis of Interface Between Cu Substrate and Al2O3 Film Formed by Aerosol Deposition Method

    NASA Astrophysics Data System (ADS)

    Naoe, Kazuaki; Nishiki, Masashi; Sato, Keishi

    2014-12-01

    Aerosol deposition method is a technique to form dense films by impacting solid particles on a substrate at room temperature. To clarify the bonding mechanism between AD films and substrates, TEM observation and electron energy-loss spectroscopy (EELS) analysis of the interface between Al2O3 AD films and Cu substrates were conducted. The Al2O3 film was directly adhered to the Cu substrate without any void or crack. The film was composed of randomly oriented α-Al2O3 crystal grains of about 10-20 nm large. At the Al2O3/Cu interface, the lattice fringes of the film were recognized, and no interfacial layer with nanometer-order thickness could be found. EELS spectra near O- K edge obtained at the interface had the pre-peak feature at around 528 eV. According to previously reported experiments and theoretical calculations, this suggests interactions between Cu and O in Al2O3 at the interface. It is inferred that not only the anchoring effect but also the ionic bonding and covalent bonding that originates from the Cu-O interactions contribute to the bonding between Al2O3 AD films and Cu substrates.

  6. Direct band gap measurement of Cu(In,Ga)(Se,S){sub 2} thin films using high-resolution reflection electron energy loss spectroscopy

    SciTech Connect

    Heo, Sung; Lee, Hyung-Ik; Park, Jong-Bong; Ko, Dong-Su; Chung, JaeGwan; Kim, KiHong; Kim, Seong Heon; Yun, Dong-Jin; Ham, YongNam; Park, Gyeong Su; Song, Taewon; Lee, Dongho Nam, Junggyu; Kang, Hee Jae; Choi, Pyung-Ho; Choi, Byoung-Deog

    2015-06-29

    To investigate the band gap profile of Cu(In{sub 1−x},Ga{sub x})(Se{sub 1−y}S{sub y}){sub 2} of various compositions, we measured the band gap profile directly as a function of in-depth using high-resolution reflection energy loss spectroscopy (HR-REELS), which was compared with the band gap profile calculated based on the auger depth profile. The band gap profile is a double-graded band gap as a function of in-depth. The calculated band gap obtained from the auger depth profile seems to be larger than that by HR-REELS. Calculated band gaps are to measure the average band gap of the spatially different varying compositions with respect to considering its void fraction. But, the results obtained using HR-REELS are to be affected by the low band gap (i.e., out of void) rather than large one (i.e., near void). Our findings suggest an analytical method to directly determine the band gap profile as function of in-depth.

  7. Probing optical band gaps at the nanoscale in NiFe₂O₄ and CoFe₂O₄ epitaxial films by high resolution electron energy loss spectroscopy

    SciTech Connect

    Dileep, K.; Loukya, B.; Datta, R.; Pachauri, N.; Gupta, A.

    2014-09-14

    Nanoscale optical band gap variations in epitaxial thin films of two different spinel ferrites, i.e., NiFe₂O₄ (NFO) and CoFe₂O₄ (CFO), have been investigated by spatially resolved high resolution electron energy loss spectroscopy. Experimentally, both NFO and CFO show indirect/direct band gaps around 1.52 eV/2.74 and 2.3 eV, and 1.3 eV/2.31 eV, respectively, for the ideal inverse spinel configuration with considerable standard deviation in the band gap values for CFO due to various levels of deviation from the ideal inverse spinel structure. Direct probing of the regions in both the systems with tetrahedral A site cation vacancy, which is distinct from the ideal inverse spinel configuration, shows significantly smaller band gap values. The experimental results are supported by the density functional theory based modified Becke-Johnson exchange correlation potential calculated band gap values for the different cation configurations.

  8. Optical dark field and electron energy loss imaging and spectroscopy of symmetry-forbidden modes in loaded nanogap antennas (Presentation Recording)

    NASA Astrophysics Data System (ADS)

    Brintlinger, Todd; Herzing, Andrew; Long, James P.; Vurgaftman, Igor; Stroud, Rhonda; Simpkins, Blake S.

    2015-09-01

    Theoretical work has identified a new type of hybrid nanoresonator akin to a loaded-gap antenna, wherein the gap between two collinearly aligned metal nanorods is filled with active dielectric material. The gap optical load has a profound impact on resonances supported by such a "nanogap" antenna, and thus provides opportunity for (i) active modulation of the antenna resonance and (ii) delivery of substantial energy to the gap material. To this end, we have (i) used a bottom-up technique to fabricate nanogap antennas (Au/CdS/Au); (ii) characterized the optical modes of individual antennas with polarization- and wavevector-controlled dark-field microscopy; (iii) mapped the spatial profiles of the dominant modes with electron energy loss spectroscopy and imaging; and (iv) utilized full-wave finite-difference time-domain simulations to reveal the nanoscopic origin of the radiating modes supported on such nanogap antennas. In addition to conventional transverse and longitudinal resonances, these loaded nanogap antennas support a unique symmetry-forbidden gap-localized transverse mode arising from the splitting of degenerate transverse modes located on the two gap faces. This previously unobserved mode is strong (E2 enhanced ~20), tightly localized in the nanoscopic (~30 nm separation) gap region, and is shown to red-shift with decreased gap size and increased gap dielectric constant. In fact, the mode is highly suppressed in air-gapped structures which may explain its absence from the literature to date. Understanding the complex modal structure supported on hybrid nanosystems is necessary to enable the multi-functional components many seek.

  9. Electron energy loss spectroscopy of CH/sub 3/N/sub 2/CH/sub 3/ adsorbed on Ni(100), Ni(111), Cr(100), Cr(111)

    SciTech Connect

    Schulz, M.A.

    1985-07-01

    A study of the adsorption of CH/sub 3/N/sub 2/CH/sub 3/ on Ni(100), Ni(111), Cr(100), and Cr(111) using high resolution electron energy loss spectroscopy (EELS) is presented. Under approximately the same conditions of coverage, the vibrational spectra of CH/sub 3/N/sub 2/CH/sub 3/ on these four surfaces are quite distinct from one another, implying that the CH/sub 3/N/sub 2/CH/sub 3/-substrate interaction is very sensitive to the physical and electronic structure of each surface. In addition to the room temperature studies, the evolution of surface species on the Ni(100) surface in the temperature range 300 to 425 K was studied. Analysis of the Ni(100) spectra indicates that molecular adsorption, probably through the N lone pair, occurs at room temperature. Spectra taken after annealing the CH/sub 3/N/sub 2/CH/sub 3/-Ni(100) surfaces indicate that CH and CN bond scission occurred at the elevated temperatures. Decomposition of CH/sub 3/N/sub 2/CH/sub 3/ takes place on the Ni(111), Cr(100), and Cr(111) surfaces at room temperature, as evidenced by the intensity of the carbon-metal stretch in the corresponding spectra. Possible identities of coadsorbed dissociation products are considered. The stable coverage of surface species on all four surfaces at 300 K is less than one monolayer. A general description of an electron energy loss (EEL) spectrometer is given. Followed by a more specific discussion of some recent modifications to the EEL monochromator assembly used in this laboratory. Both the previous configuration of our monochromator and the new version are briefly described, as an aid to understanding the motivation for the changes as well as the differences in operation of the two versions. For clarity, the new monochromator design is referred to as variable pass, while the previous design is referred to as double pass. A modified tuning procedure for the new monochromator is also presented. 58 refs., 11 figs.

  10. Dynamical observation of lithium insertion/extraction reaction during charge-discharge processes in Li-ion batteries by in situ spatially resolved electron energy-loss spectroscopy.

    PubMed

    Shimoyamada, Atsushi; Yamamoto, Kazuo; Yoshida, Ryuji; Kato, Takehisa; Iriyama, Yasutoshi; Hirayama, Tsukasa

    2015-12-01

    All-solid-state Li-ion batteries (LIBs) with solid electrolytes are expected to be the next generation devices to overcome serious issues facing conventional LIBs with liquid electrolytes. However, the large Li-ion transfer resistance at the electrode/solid-electrolyte interfaces causes low power density and prevents practical use. In-situ-formed negative electrodes prepared by decomposing the solid electrolyte Li(1+x+3z)Alx(Ti,Ge)(2-x)Si(3z)P(3-z)O12 (LASGTP) with an excess Li-ion insertion reaction are effective electrodes providing low Li-ion transfer resistance at the interfaces. Prior to our work, however, it had still been unclear how the negative electrodes were formed in the parent solid electrolytes. Here, we succeeded in dynamically visualizing the formation by in situ spatially resolved electron energy-loss spectroscopy in a transmission electron microscope mode (SR-TEM-EELS). The Li-ions were gradually inserted into the solid electrolyte region around 400 nm from the negative current-collector/solid-electrolyte interface in the charge process. Some of the ions were then extracted in the discharge process, and the rest were diffused such that the distribution was almost flat, resulting in the negative electrodes. The redox reaction of Ti(4+)/Ti(3+) in the solid electrolyte was also observed in situ during the Li insertion/extraction processes. The in situ SR-TEM-EELS revealed the mechanism of the electrochemical reaction in solid-state batteries. PMID:26337787

  11. An energy loss straggling formula

    NASA Astrophysics Data System (ADS)

    Novković, D.; Subotić, K.; Milošević, Z.; Manić, S.; Stojanović, M.

    1994-12-01

    The analytical formulae for straggling widths were obtained solving Symon's equations for the second and third order central moments of the straggling distributions in non-relativistic approximation, enabling prediction of peak widths and asymmetry parameters of charged particle energy loss distributions for thick targets. The respective calculations based on these formulae were found to be in good agreement with experimental values for particle energy losses of light ions up to 70% of the nominal projectile energy value.

  12. Spectral restoration in high resolution electron energy loss spectroscopy based on iterative semi-blind Lucy-Richardson algorithm applied to rutile surfaces

    NASA Astrophysics Data System (ADS)

    Lazzari, Rémi; Li, Jingfeng; Jupille, Jacques

    2015-01-01

    A new spectral restoration algorithm of reflection electron energy loss spectra is proposed. It is based on the maximum likelihood principle as implemented in the iterative Lucy-Richardson approach. Resolution is enhanced and point spread function recovered in a semi-blind way by forcing cyclically the zero loss to converge towards a Dirac peak. Synthetic phonon spectra of TiO2 are used as a test bed to discuss resolution enhancement, convergence benefit, stability towards noise, and apparatus function recovery. Attention is focused on the interplay between spectral restoration and quasi-elastic broadening due to free carriers. A resolution enhancement by a factor up to 6 on the elastic peak width can be obtained on experimental spectra of TiO2(110) and helps revealing mixed phonon/plasmon excitations.

  13. Spectral restoration in high resolution electron energy loss spectroscopy based on iterative semi-blind Lucy-Richardson algorithm applied to rutile surfaces

    SciTech Connect

    Lazzari, Rémi Li, Jingfeng Jupille, Jacques

    2015-01-15

    A new spectral restoration algorithm of reflection electron energy loss spectra is proposed. It is based on the maximum likelihood principle as implemented in the iterative Lucy-Richardson approach. Resolution is enhanced and point spread function recovered in a semi-blind way by forcing cyclically the zero loss to converge towards a Dirac peak. Synthetic phonon spectra of TiO{sub 2} are used as a test bed to discuss resolution enhancement, convergence benefit, stability towards noise, and apparatus function recovery. Attention is focused on the interplay between spectral restoration and quasi-elastic broadening due to free carriers. A resolution enhancement by a factor up to 6 on the elastic peak width can be obtained on experimental spectra of TiO{sub 2}(110) and helps revealing mixed phonon/plasmon excitations.

  14. Energy losses during cooking processes

    SciTech Connect

    Thapar, A.; Engira, R.M.; Sohal, J.S.

    1983-12-01

    A major chunk of the thermal energy of the cooking fuel is wasted due to incomplete consumption, unfunctional design of cooking stoves and utensils. Several studies and their findings which are reported in the present paper pertain to: determination of minimum fuel consumption required for cooking of selected dishes under controlled and normal conditions; analysis of relative amounts of heat loss through different techniques during cooking under normal conditions; evaluation of effectiveness of different energy saving techniques with regard to cooking vessel.

  15. Evidence for anisotropic dielectric properties of monoclinic hafnia using valence electron energy-loss spectroscopy in high-resolution transmission electron microscopy and ab initio time-dependent density-functional theory

    NASA Astrophysics Data System (ADS)

    Guedj, C.; Hung, L.; Zobelli, A.; Blaise, P.; Sottile, F.; Olevano, V.

    2014-12-01

    The effect of nanocrystal orientation on the energy loss spectra of monoclinic hafnia (m-HfO2) is measured by high resolution transmission electron microscopy (HRTEM) and valence energy loss spectroscopy (VEELS) on high quality samples. For the same momentum-transfer directions, the dielectric properties are also calculated ab initio by time-dependent density-functional theory (TDDFT). Experiments and simulations evidence anisotropy in the dielectric properties of m-HfO2, most notably with the direction-dependent oscillator strength of the main bulk plasmon. The anisotropic nature of m-HfO2 may contribute to the differences among VEELS spectra reported in literature. The good agreement between the complex dielectric permittivity extracted from VEELS with nanometer spatial resolution, TDDFT modeling, and past literature demonstrates that the present HRTEM-VEELS device-oriented methodology is a possible solution to the difficult nanocharacterization challenges given in the International Technology Roadmap for Semiconductors.

  16. Evidence for anisotropic dielectric properties of monoclinic hafnia using valence electron energy-loss spectroscopy in high-resolution transmission electron microscopy and ab initio time-dependent density-functional theory

    SciTech Connect

    Guedj, C.; Hung, L.; Sottile, F.; Zobelli, A.; Blaise, P.; Olevano, V.

    2014-12-01

    The effect of nanocrystal orientation on the energy loss spectra of monoclinic hafnia (m-HfO{sub 2}) is measured by high resolution transmission electron microscopy (HRTEM) and valence energy loss spectroscopy (VEELS) on high quality samples. For the same momentum-transfer directions, the dielectric properties are also calculated ab initio by time-dependent density-functional theory (TDDFT). Experiments and simulations evidence anisotropy in the dielectric properties of m-HfO{sub 2}, most notably with the direction-dependent oscillator strength of the main bulk plasmon. The anisotropic nature of m-HfO{sub 2} may contribute to the differences among VEELS spectra reported in literature. The good agreement between the complex dielectric permittivity extracted from VEELS with nanometer spatial resolution, TDDFT modeling, and past literature demonstrates that the present HRTEM-VEELS device-oriented methodology is a possible solution to the difficult nanocharacterization challenges given in the International Technology Roadmap for Semiconductors.

  17. Energy loss in general relativity

    SciTech Connect

    Cooperstock, F.I.; Lim, P.H.

    1987-07-15

    Implicit assumptions regarding continuity in energy-loss calculations in general relativity are examined. The Arnowitt-Deser-Misner energy integral is treated in a new manner as a universal vehicle for energy loss. Two explicit examples are given: the electric dipole radiation flux is computed using general relativity as well as the gravitational-radiation flux from a linear mass quadrupole oscillator. In this approach, the latter is seen as a nonlinear problem in the sense that the lower-order metric serves as a source for the required order metric as computed within the wave front. Logarithmic terms which threaten to induce divergences, as has been found in other works, are averted by functions of integration which are required to sustain the gauge conditions and finally yield the usual fluxes.

  18. Efficient modal-expansion discrete-dipole approximation: Application to the simulation of optical extinction and electron energy-loss spectroscopies

    NASA Astrophysics Data System (ADS)

    Guillaume, Stéphane-Olivier; de Abajo, F. Javier García; Henrard, Luc

    2013-12-01

    An efficient procedure is introduced for the calculation of the optical response of individual and coupled metallic nanoparticles in the framework of the discrete-dipole approximation (DDA). We introduce a modal expansion in the basis set of discrete dipoles and show that a few suitably selected modes are sufficient to compute optical spectra with reasonable accuracy, thus reducing the required numerical effort relative to other DDA approaches. Our method offers a natural framework for the study of localized plasmon modes, including plasmon hybridization. As a proof of concept, we investigate optical extinction and electron energy-loss spectra of monomers, dimers, and quadrumers formed by flat silver squares. This method should find application to the previously prohibited simulation of complex particle arrays.

  19. QCD Collisional Energy Loss Reexamined

    NASA Astrophysics Data System (ADS)

    Peshier, A.

    2006-11-01

    It is shown that at a large temperature and E→∞ the QCD collisional energy loss reads dE/dx˜α(mD2)T2. Compared to previous approaches, which led to dEB/dx˜α2T2ln⁡(ET/mD2) similar to the Bethe-Bloch formula in QED, we take into account the running of the strong coupling. As one significant consequence, due to asymptotic freedom, dE/dx becomes E independent for large parton energies. Some implications with regard to heavy ion collisions are pointed out.

  20. QCD collisional energy loss reexamined.

    PubMed

    Peshier, A

    2006-11-24

    It is shown that at a large temperature and E --> infinity the QCD collisional energy loss reads dE/dx approximately alpha(m(D)2)T2. Compared to previous approaches, which led to dE(B)/dx approximately alpha2 T2 ln(ET/m(D)2) similar to the Bethe-Bloch formula in QED, we take into account the running of the strong coupling. As one significant consequence, due to asymptotic freedom, dE/dx becomes E independent for large parton energies. Some implications with regard to heavy ion collisions are pointed out. PMID:17155739

  1. Layer specific optical band gap measurement at nanoscale in MoS2 and ReS2 van der Waals compounds by high resolution electron energy loss spectroscopy

    NASA Astrophysics Data System (ADS)

    Dileep, K.; Sahu, R.; Sarkar, Sumanta; Peter, Sebastian C.; Datta, R.

    2016-03-01

    Layer specific direct measurement of optical band gaps of two important van der Waals compounds, MoS2 and ReS2, is performed at nanoscale by high resolution electron energy loss spectroscopy. For monolayer MoS2, the twin excitons (1.8 and 1.95 eV) originating at the K point of the Brillouin zone are observed. An indirect band gap of 1.27 eV is obtained from the multilayer regions. Indirect to direct band gap crossover is observed which is consistent with the previously reported strong photoluminescence from the monolayer MoS2. For ReS2, the band gap is direct, and a value of 1.52 and 1.42 eV is obtained for the monolayer and multilayer, respectively. The energy loss function is dominated by features due to high density of states at both the valence and conduction band edges, and the difference in analyzing band gap with respect to ZnO is highlighted. Crystalline 1T ReS2 forms two dimensional chains like superstructure due to the clustering between four Re atoms. The results demonstrate the power of HREELS technique as a nanoscale optical absorption spectroscopy tool.

  2. Electron energy-loss spectra in molecular fluorine

    NASA Technical Reports Server (NTRS)

    Nishimura, H.; Cartwright, D. C.; Trajmar, S.

    1979-01-01

    Electron energy-loss spectra in molecular fluorine, for energy losses from 0 to 17.0 eV, have been taken at incident electron energies of 30, 50, and 90 eV and scattering angles from 5 to 140 deg. Features in the spectra above 11.5 eV energy loss agree well with the assignments recently made from optical spectroscopy. Excitations of many of the eleven repulsive valence excited electronic states are observed and their location correlates reasonably well with recent theoretical results. Several of these excitations have been observed for the first time and four features, for which there are no identifications, appear in the spectra.

  3. Far-UV Spectroscopy of the Planet-hosting Star WASP-13: High-energy Irradiance, Distance, Age, Planetary Mass-loss Rate, and Circumstellar Environment

    NASA Astrophysics Data System (ADS)

    Fossati, L.; France, K.; Koskinen, T.; Juvan, I. G.; Haswell, C. A.; Lendl, M.

    2015-12-01

    Several transiting hot Jupiters orbit relatively inactive main-sequence stars. For some of those, the {log}{R}{HK}\\prime activity parameter lies below the basal level (-5.1). Two explanations have been proposed so far: (i) the planet affects the stellar dynamo, (ii) the {log}{R}{HK}\\prime measurements are biased by extrinsic absorption, either by the interstellar medium (ISM) or by material local to the system. We present here Hubble Space Telescope/COS far-UV spectra of WASP-13, which hosts an inflated hot Jupiter and has a measured {log}{R}{HK}\\prime value (-5.26), well below the basal level. From the star's spectral energy distribution we obtain an extinction E(B - V) = 0.045 ± 0.025 mag and a distance d = 232 ± 8 pc. We detect at ≳4σ lines belonging to three different ionization states of carbon (C i, C ii, and C iv) and the Si iv doublet at ˜3σ. Using far-UV spectra of nearby early G-type stars of known age, we derive a C iv/C i flux ratio-age relation, from which we estimate WASP-13's age to be 5.1 ± 2.0 Gyr. We rescale the solar irradiance reference spectrum to match the flux of the C iv 1548 doublet. By integrating the rescaled solar spectrum, we obtain an XUV flux at 1 AU of 5.4 erg s-1 cm-2. We use a detailed model of the planet's upper atmosphere, deriving a mass-loss rate of 1.5 × 1011 g s-1. Despite the low {log}{R}{HK}\\prime value, the star shows a far-UV spectrum typical of middle-aged solar-type stars, pointing toward the presence of significant extrinsic absorption. The analysis of a high-resolution spectrum of the Ca ii H&K lines indicates that the ISM absorption could be the origin of the low {log}{R}{HK}\\prime value. Nevertheless, the large uncertainty in the Ca ii ISM abundance does not allow us to firmly exclude the presence of circumstellar gas. Based on observations made with the NASA/ESA Hubble Space Telescope, obtained from MAST at the Space Telescope Science Institute, which is operated by the Association of Universities for

  4. Ultrafast core-loss spectroscopy in four-dimensional electron microscopy

    PubMed Central

    van der Veen, Renske M.; Penfold, Thomas J.; Zewail, Ahmed H.

    2015-01-01

    We demonstrate ultrafast core-electron energy-loss spectroscopy in four-dimensional electron microscopy as an element-specific probe of nanoscale dynamics. We apply it to the study of photoexcited graphite with femtosecond and nanosecond resolutions. The transient core-loss spectra, in combination with ab initio molecular dynamics simulations, reveal the elongation of the carbon-carbon bonds, even though the overall behavior is a contraction of the crystal lattice. A prompt energy-gap shrinkage is observed on the picosecond time scale, which is caused by local bond length elongation and the direct renormalization of band energies due to temperature-dependent electron–phonon interactions. PMID:26798793

  5. Nano-scale simultaneous observation of Li-concentration profile and Ti-, O electronic structure changes in an all-solid-state Li-ion battery by spatially-resolved electron energy-loss spectroscopy

    NASA Astrophysics Data System (ADS)

    Yamamoto, Kazuo; Yoshida, Ryuji; Sato, Takeshi; Matsumoto, Hiroaki; Kurobe, Hisanori; Hamanaka, Tadashi; Kato, Takehisa; Iriyama, Yasutoshi; Hirayama, Tsukasa

    2014-11-01

    All-solid-state Li-ion batteries having incombustible solid electrolytes are expected to be promising candidates for safe next-generation energy storage devices that have a long lifetime and high energy density. However, it is essential to address the large resistance of Li-ion transfer at the electrode/solid-electrolyte interfaces. A new concept electrode that is formed in situ from the Li2O-Al2O3-TiO2-P2O5-based glass-ceramic solid electrolytes with Si and Ge doping (LASGTP) produces atomic scale connection at the interfaces, which provides extremely low interfacial resistance. However, the formation mechanism and the reason for the low resistance are still unclear. Here we applied spatially-resolved electron energy-loss spectroscopy in a transmission electron microscope mode (SR-TEM-EELS) to visualize the nanometer-scale Li distribution and its effects on the electronic structures of other important elements (Ti and O). Local electron diffraction showed that the in situ formed electrode was an amorphous phase caused by the Li insertion. Picometer-scale expansion of O-O distance due to the Li insertion was also visualized in the electrode. These electronic and crystal changes and gradual Li distribution contribute to the low resistance and stable battery cycles.

  6. Single atom identification by energy dispersive x-ray spectroscopy

    SciTech Connect

    Lovejoy, T. C.; Dellby, N.; Krivanek, O. L.; Ramasse, Q. M.; Falke, M.; Kaeppel, A.; Terborg, R.; Zan, R.

    2012-04-09

    Using aberration-corrected scanning transmission electron microscope and energy dispersive x-ray spectroscopy, single, isolated impurity atoms of silicon and platinum in monolayer and multilayer graphene are identified. Simultaneously acquired electron energy loss spectra confirm the elemental identification. Contamination difficulties are overcome by employing near-UHV sample conditions. Signal intensities agree within a factor of two with standardless estimates.

  7. Equilibration Influence on Jet Energy Loss

    SciTech Connect

    Cheng Luan; Wang Enke

    2010-05-12

    With the initial conditions in the chemical non-equilibrated medium and Bjorken expanding medium at RHIC, we investigate the consequence for parton evolution. With considering the parton equilibration, we obtain the time dependence of the opacity when the jet propagates through the QGP medium. The parton equilibration affect the jet energy loss with detailed balance evidently. Both parton energy loss from stimulated emission in the chemical non-equilibrated expanding medium and in Bjorken expanding medium are linear dependent on the propagating distance rather than square dependent in the static medium. This will increase the energy and propagating distance dependence of the parton energy loss.

  8. Inverse Raman bands in ultrafast Raman loss spectroscopy

    NASA Astrophysics Data System (ADS)

    Qiu, Xueqiong; Li, Xiuting; Niu, Kai; Lee, Soo-Y.

    2011-10-01

    Ultrafast Raman loss spectroscopy (URLS) is equivalent to anti-Stokes femtosecond stimulated Raman spectroscopy (FSRS), using a broadband probe pulse that extends to the blue of the narrow bandwidth Raman pump, and can be described as inverse Raman scattering (IRS). Using the Feynman dual time-line diagram, the third-order polarization for IRS with finite pulses can be written down in terms of a four-time correlation function. An analytic expression is obtained for the latter in the harmonic approximation which facilitates computation. We simulated the URLS of crystal violet (CV) for various resonance Raman pump excitation wavelengths using the IRS polarization expression with finite pulses. The calculated results agreed well with the experimental results of S. Umapathy et al., J. Chem. Phys. 133, 024505 (2010). In the limit of monochromatic Raman pump and probe pulses, we obtain the third-order susceptibility for multi-modes, and for a single mode we recover the well-known expression for the third-order susceptibility, χ _{IRS}^{(3)}, for IRS. The latter is used to understand the mode dependent phase changes as a function of Raman pump excitation in the URLS of CV.

  9. Stratospheric ozone loss, ultraviolet effects and action spectroscopy

    NASA Astrophysics Data System (ADS)

    Coohill, Thomas P.

    The major effect of stratospheric ozone loss will be an increase in the amount of ultraviolet radiation reaching the ground. This increase will be entirely contained within the UV-B (290-320nm). How this will impact life on Earth will be determined by the UV-B photobiology of exposed organisms, including humans. One of the analytical methods useful in estimating these effects is Action Spectroscopy (biological effect as a function of wavelength). Carefully constructed action spectra will allow us to partially predict the increase in bio-effect due to additional UV exposure. What effect this has on the organism and the system in which the organism resides is of paramount importance. Suitable action spectra already exist for human skin cancer, human cell mutation and killing, and for one immune response. Comprehensive and widely applicable action spectra for terrestrial and aquatic plant responses are being generated but are not yet suitable for extensive analysis. There is little data available for animals, other than those experiments completed in the laboratory as model systems for human studies. Some polychromatic action spectra have proven useful in determining the possible impact of ozone loss on biological systems. The pitfalls and limits of this approach will be addressed.

  10. Energy loss measurement of cosmic ray muons

    NASA Astrophysics Data System (ADS)

    Unger, Joseph

    1993-02-01

    Measurements of energy losses of high energy cosmic ray muons in an ionization chamber are presented. The chamber consists of 16 single gap layers, and the liquid tetra methyl silane (TMS) was used as active medium. The absolute energy loss and the relativistic rise were measured and compared with theoretical calculations. The importance of the measurements within the framework of the cosmic ray experiment KASCADE (German acronym for Karlsruhe Shower Core and Array Detector) are discussed, especially with respect to energy calibration of hadrons and high energy muons above 1 TeV.

  11. Enhancement of resolution in core-loss and low-loss spectroscopy in a monochromated microscope.

    PubMed

    Lazar, S; Botton, G A; Zandbergen, H W

    2006-01-01

    The significant enhancement of the energy resolution in the new generation of commercially available monochromated transmission electron microscopes presents new challenges in term of selecting the correct experimental conditions and understanding the various effects that can potentially influence the quality of the EELS data. In this respect we investigated the effect of point spread function of the detector and spectrum-diffraction mixing on the energy resolution and the intensity of the zero loss peak tails. Alternative approaches to improve the energy resolution by mathematical methods have been tested. By using a simple and commonly available test case (Si L(2,3) edges) we assessed the efficiency of the deconvolution algorithms to improve the resolution. The results show that the deconvolution is not always successful in improving the resolution of the core loss EELS data and the results may not always be reliable. Contrary to this, the application of the Richardson-Lucy deconvolution algorithm on some bandgap measurements data appears to be very effective. The procedure proved successful in removing the contribution of the zero-loss peak tails and allows an easier access to spectroscopic information starting at energy losses as low as of 0.5 eV with monochromated spectra and 1 eV with the non-monochromated spectra. PMID:16872750

  12. Heat recovery reduces process energy losses

    SciTech Connect

    Anon

    1981-09-01

    After evaluation of process and plant operation losses, a pharmaceutical plant found heat recovery a viable means of reducing energy losses. One of the first applications of air-to-air heat recovery was in a recirculation/dehumidification process. Heat exchangers were used to recover heat from the air used to generate or dry the dehumidification material.

  13. Background fitting for electron energy-loss spectra

    SciTech Connect

    Bentley, J.; Lehman, G.L.; Sklad, P.S.

    1981-01-01

    Microanalysis using electron energy loss spectroscopy is now well established. In order to assess true edge profiles and obtain integrated intensities of the inner shell ionization edges of interest, it is first necessary to subtract the background. Usually a simple inverse power law is used, but for some spectra this form does not fit well. An alternative form which results in superior fits is described.

  14. New insights into the chemical structure of Y2Ti2O7-δ nanoparticles in oxide dispersion-strengthened steels designed for sodium fast reactors by electron energy-loss spectroscopy

    NASA Astrophysics Data System (ADS)

    Badjeck, V.; Walls, M. G.; Chaffron, L.; Malaplate, J.; March, K.

    2015-01-01

    In this paper we study by high resolution scanning transmission electron microscopy coupled with electron energy-loss spectroscopy (STEM-EELS) an oxide dispersion-strengthened (ODS) steel with the nominal composition Fe-14Cr-1W-0.3TiH2-0.3Y2O3 (wt.%) designed to withstand the extreme conditions met in Gen. IV nuclear reactors. After denoising via principal component analysis (PCA) the data are analyzed using independent component analysis (ICA) which is useful in the investigation of the physical properties and chemical structure of the material by separating the individual spectral responses. The Y-Ti-O nanoparticles are found to be homogeneously distributed in the ferritic matrix, sized from 1 to 20 nm and match a non-stoichiometric pyrochlore-Y2Ti2O7-δ structure for sizes greater than 5 nm. We show that they adopt a (Y-Ti-O)-Cr core-shell structure and that Cr also segregates at the matrix grain boundaries, which may slightly modify the corrosion properties of the steel. Using Ti-L2,3 and O-K fine structure (ELNES) the Ti oxidation state is shown to vary from the center of the nanoparticles to their periphery, from Ti4+ in distorted Oh symmetry to a valency often lower than 3+. The sensitivity of the Ti "white lines" ELNES to local symmetry distortions is also shown to be useful when investigating the strain induced in the nanoparticles by the surrounding matrix. The Cr-shell and the variation of the Ti valence state highlight a complex nanoparticle-matrix interface.

  15. Applications of energy loss contrast STIM

    SciTech Connect

    Bench, G.; Saint, A.; Legge, G.J.F.; Cholewa, M.

    1992-05-26

    Scanning Transmission Ion Microscopy (STIM) with energy loss contrast is a quantitative imaging technique. A focussed MeV ion microbeam is scanned over the sample and measured energy losses of residual ions at each beam location are used to provide the contrast in the image. The technique is highly efficient as almost every ion carries useful information from which quantitative data can be obtained. The high efficiency of data collection at present necessitates the use of small beam currents. Therefore small apertures can be used and fine spatial resolution can be achieved. High efficiency also makes it possible to collect large data sets for high definition imaging with a small radiation dose. Owing to the simple relationship between energy loss and areal density, STIM with energy loss contrast can provide a quantitative image that can be used to obtain areal density information on the sample. These areal density maps can be used not only to provide a high resolution image of the sample but also to normalise Particle Induced Xray Emission (PIXE) data. The small radiation dose required to form these areal density maps also allows one to use STIM with energy loss contrast to quantitatively monitor ion beam induced specimen changes caused by higher doses and dose rates used in other microanalytical techniques. STIM with energy loss contrast also provides the possibility of stereo imaging and ion microtomography. STIM has also been used in conjunction with channeling to explore transmission channeling in thin crystals. This paper will discuss these applications of STIM with energy loss contrast and look at further developments from them.

  16. Electron energy loss spectrometry of interstellar diamonds

    NASA Technical Reports Server (NTRS)

    Bernatowicz, Thomas J.; Gibbons, Patrick C.; Lewis, Roy S.

    1990-01-01

    The results are reported of electron energy loss spectra (EELS) measurements on diamond residues from carbonaceous meteorites designed to elucidate the structure and composition of interstellar diamonds. Dynamic effective medium theory is used to model the dielectric properties of the diamonds and in particular to synthesize the observed spectra as mixtures of diamond and various pi-bonded carbons. The results are shown to be quantitatively consistent with the idea that diamonds and their surfaces are the only contributors to the electron energy loss spectra of the diamond residues and that these peculiar spectra are the result of the exceptionally small grain size and large specific surface area of the interstellar diamonds.

  17. New Mechanism for Quark Energy Loss

    SciTech Connect

    Casalderrey-Solana, Jorge; Fernandez, Daniel; Mateos, David

    2010-04-30

    We show that a heavy quark moving sufficiently fast through a quark-gluon plasma may lose energy by Cherenkov-radiating mesons. We demonstrate that this takes place in all strongly coupled, large-N{sub c} plasmas with a gravity dual. The energy loss is exactly calculable in these models despite being an O(1/N{sub c}) effect. We discuss implications for heavy-ion collision experiments.

  18. Energy-loss function of TTF-TCNQ

    NASA Astrophysics Data System (ADS)

    Lošić, Željana Bonačić

    2012-02-01

    We investigate the energy-loss function for a previously developed model of quasi-one-dimensional metals with two one-dimensional electron bands per donor and acceptor chains and the three-dimensional long-range Coulomb electron-electron interaction within the random phase approximation. It is essentially influenced by two hybridized collective modes which result from the strong coupling of the intraband plasmon and the interband dipolar modes. Our calculations show that the spectral weights of the renormalized plasmon and the dipolar mode dominate within the long wavelength limit, while for large longitudinal wave vectors the intraband electron-hole quasi-continuumgains some experimentally observable spectral weight as the second mode approaches it. The function obtained is brought into correspondence with the data of the quasi-one-dimensional organic conductor tetrathiafulvalene-tetracyanoquinodimethane (TTF-TCNQ) obtained from electron energy-loss spectroscopy (EELS) measurements.

  19. RHIC low energy beam loss projections

    SciTech Connect

    Satogata,T.

    2009-08-01

    For RHIC low-energy operations, we plan to collide Au beams with energies of E = 2:5-10 GeV/u in RHIC. Beams are injected into collision optics, and RHIC runs as a storage ring with no acceleration. At these low energies, observed beam lifetimes are minutes, with measured beam lifetimes of 3.5 min (fast) and 50 min (slow) at E=4.6 GeV/u in the March 2008 test run. With these lifetimes we can operate RHIC as a storage ring to produce reasonable integrated luminosity. This note estimates beam losses and collimator/dump energy deposition in normal injection modes of low energy operation. The main question is whether a normal injection run is feasible for an FY10 10-15 week operations run from a radiation safety perspective. A peripheral question is whether continuous injection operations is feasible from a radiation safety perspective. In continuous injection mode, we fill both rings, then continuously extract and reinject the oldest bunches that have suffered the most beam loss to increase the overall integrated luminosity. We expect to gain a factor of 2-3 in integrated luminosity from continuous injection at lowest energies if implemented[1]. Continuous injection is feasible by FY11 from an engineering perspective given enough effort, but the required extra safety controls and hardware dose risk make it unappealing for the projected luminosity improvement. Low-energy electron cooling will reduce beam losses by at least an order of magnitude vs normal low-energy operations, but low energy cooling is only feasible in the FY13 timescale and therefore beyond the scope of this note. For normal injection low energy estimates we assume the following: (1) RHIC beam total energies are E=2.5-10 GeV/u. (Continuous injection mode is probably unnecessary above total energies of E=7-8 GeV/u.); (2) RHIC operates only as a storage ring, with no acceleration; (3) 110 bunches of about 0.5-1.0 x 10{sup 9} initial bunch intensities (50-100% injection efficiency, likely conservative

  20. Electron-energy losses in hemispherical targets

    SciTech Connect

    Aizpurua, J.; Rivacoba, A.; Apell, S.P.

    1996-07-01

    In the framework of classical dielectric theory, the hemispherical geometry is studied. Calculations on surface modes are carried out for isolated Drude-like hemispheres. The convergence of the results with respect to the number of coupled terms in the expressions of the potential is discussed. The electron-energy-loss probability is studied for Al and Ag particles involving this geometry. The surface modes and hence the energy-loss probability are given by coupled expressions, the physical meaning of which is the coupling among multipolar terms, because of the particular geometry. The results obtained here present a good quantitative agreement with experiments in the case of clear surfaces (Ag) and provide a qualitative understanding for the experiments in Al, in terms of the position and impact parameter of the beam. This allows us to set the validity of the dielectric theory for cases that seemed to question it. {copyright} {ital 1996 The American Physical Society.}

  1. Photoneutrino energy losses in strong magnetic fields.

    NASA Technical Reports Server (NTRS)

    Canuto, V.; Fassio-Canuto, L.

    1973-01-01

    Previously computed rates of energy losses (Petrosian et al., 1967) ignored the presence of strong magnetic fields, hence the change brought in when such a field (about 10 to the 12th to 10 to the 13th power G) is included is studied. The results indicate that for T about 10 to the 8th power K and densities rho of about 10,000 g/cu cm, the presence of a strong H field decreases the energy losses by at the most a factor between 10 and 100 in the region up to rho = 1,000,000 g/cu cm. At higher densities the neutrino emissivities are almost identical.

  2. Energy loss rate in disordered quantum well

    SciTech Connect

    Tripathi, P.; Ashraf, S. S. Z.; Hasan, S. T.; Sharma, A. C.

    2014-04-24

    We report the effect of dynamically screened deformation potential on the electron energy loss rate in disordered semiconductor quantum well. Interaction of confined electrons with bulk acoustic phonons has been considered in the deformation coupling. The study concludes that the dynamically screened deformation potential coupling plays a significant role as it substantially affects the power dependency of electron relaxation on temperature and mean free path.

  3. Energy loss of hydrogen projectiles in gases

    SciTech Connect

    Schiefermueller, A.; Golser, R.; Stohl, R.; Semrad, D. )

    1993-12-01

    The stopping cross sections of H[sub 2], D[sub 2], He, and Ne for hydrogen projectiles in the energy range 3--20 keV per nucleon have been measured by time of flight. We compare our experimental result to the sum of the individual contributions due to excitation and ionization of the target and of the projectile, respectively, and due to charge exchange, using published cross-section data. Satisfactory agreement is found only for the He target and only at moderate projectile velocities, whereas for H[sub 2] and D[sub 2] the calculated values are about 30% too low. A Monte Carlo program allows us to simulate the measured time-of-flight spectra and to explain minor trends in the experimental data: for increased Ne gas pressure, an increased specific energy loss has been found that can be traced to different regions of impact parameters selected in our transmission geometry. This also explains, in part, the increased specific energy loss for deuterons compared to protons of equal velocity that is most evident for Ne. In contrast, a decrease of the specific energy loss with increasing pressure for He may be explained by impurities in the target gas. If we correct for the effect of impurities, the stopping cross section of He at 4 keV per nucleon is slightly smaller (0.60[times]10[sup [minus]15] eV cm[sup 2]) than published earlier (0.72[times]10[sup [minus]15] eV cm[sup 2]) and depends on the 3.8th power of projectile velocity.

  4. Radiative Energy Loss by Galactic Cosmic Rays

    NASA Technical Reports Server (NTRS)

    Ahern, Sean C.; Norbury, John W.; Tripathi, R. K.

    2002-01-01

    Interactions between galactic cosmic rays and matter are a primary focus of the NASA radiation problem. The electromagnetic forces involved are for the most part well documented. Building on previous research, this study investigated the relative importance of the weak forces that occur when a cosmic ray impinges on different types of materials. For the familiar electromagnetic case, it is known that energy lost in the form of radiation is more significant than that lost via contact collisions the rate at which the energy is lost is also well understood. Similar results were derived for the weak force case. It was found that radiation is also the dominant mode of energy loss in weak force interactions and that weak force effects are indeed relatively weak compared to electromagnetic effects.

  5. DYNAMICS AND ENERGY LOSS IN SUPERBUBBLES

    SciTech Connect

    Krause, Martin G. H.; Diehl, Roland

    2014-10-20

    Interstellar bubbles appear to be smaller in observations than expected from calculations. Instabilities at the shell boundaries create three-dimensional (3D) effects and are probably responsible for part of this discrepancy. We investigate instabilities and dynamics in superbubbles using 3D hydrodynamics simulations with time-resolved energy input from massive stars, including supernova explosions. We find that the superbubble shells are accelerated by supernova explosions, coincident with substantial brightening in soft X-ray emission. In between the explosions, the superbubbles lose energy efficiently, approaching the momentum-conserving snowplow limit. This and enhanced radiative losses due to instabilities reduce the expansion compared to the corresponding radiative bubbles in pressure-driven snowplow models with constant energy input. We note generally good agreement with observations of superbubbles and some open issues. In particular, there are hints that the shell velocities in the X-ray-bright phases are underpredicted.

  6. Screened energy loss rate in bilayer graphene

    NASA Astrophysics Data System (ADS)

    Ansari, Meenhaz; Ashraf, S. S. Z.; Ahmad, Afzal

    2016-05-01

    We investigate the energy relaxation of hot carriers in bilayer graphene through coupling to acoustic phonons interacting via the Deformation potential in the Boltzmann transport equation approach. We incorporate static screening in the estimation of the power loss rate as screening has a more functional role in bilayer graphene. It is observed that on the incorporation of screening the magnitude as well as the power exponent both is affected with the power exponent changed from T4 to T5.92 in the lower temperature range upto 3K and to T1.04 dependence in the higher temperature range that is 170-300K.

  7. Low energy ion loss at Mars

    NASA Astrophysics Data System (ADS)

    Curry, S.; Liemohn, M.; Fang, X.; Ma, Y.

    2012-04-01

    Current data observations and modeling efforts have indicated that the low-energy pick-up ions on Mars significantly contribute to the overall escape rate. Due to the lack of a dipole magnetic field, the solar wind directly interacts with the dayside upper atmosphere causing particles to be stripped away. In this study, we use a 3-D Monte Carlo test particle simulation with virtual detectors to observe low energy ions (< 50 eV) in the Mars space environment. We will present velocity space distributions that can capture the asymmetric and non-gyrotropic features of particle motion. The effect of different solar conditions will also be discussed with respect to ion fluxes at various spatial locations as well as overall loss in order to robustly describe the physical processes controlling the distribution of planetary ions and atmospheric escape.

  8. SPEG: An energy loss spectrometer for GANIL

    NASA Astrophysics Data System (ADS)

    Bianchi, L.; Fernandez, B.; Gastebois, J.; Gillibert, A.; Mittig, W.; Barrette, J.

    1989-04-01

    Since July 1985, an energy loss spectrometer (SPEG) is under operation at the National Heavy Ion Laboratory (GANIL), at Caen (France). It has been designed to allow the study of quantum states populated in reactions induced by nuclei accelerated at energies up to 100 A MeV. The spectrometer has been designed by P. Birien. The optical properties and the main magnetic features have been calculated by Birien and Valero. A detailed reported of their study is given in ref. [1]. In the first part of the present paper, after recalling the specifications of the spectrometer, we shall give an overall description of the main characteristics, together with indications about the various shimming procedures which have been used to achieve the desired resolution (sections 1-4). In the second part, we shall describe various accessories and the different kinds of detectors which are used during experiments, with several illustrations of experimental results (sections 5 and 6).

  9. Energy losses in mechanically modified bacterial magnetosomes

    NASA Astrophysics Data System (ADS)

    Molcan, Matus; Gojzewski, Hubert; Skumiel, Andrzej; Dutz, Silvio; Kovac, Jozef; Kubovcikova, Martina; Kopcansky, Peter; Vekas, Ladislau; Timko, Milan

    2016-09-01

    Magnetosomes are isolated from the Magnetospirillum magneticum strain AMB-1 bacteria. Two samples are compared: magnetosomes normally prepared of a ‘standard’ length and magnetosomes of a short length. Chains of magnetosomes are shortened by mechanical modification (cleavage) by means of sonication treatment. They represent a new geometry of magnetosomes that have not been investigated before. The effect of the sonication is analysed using transmission and electron microscopy, atomic force microscopy, and dynamic light scattering. Scanning imaging reveals three types of shortening effect in a sample of shortened magnetosomes, namely, membrane collapse, membrane destruction, and magnetosome cleavage. Dynamic light scattering shows a reduction of hydrodynamic diameter in a sample of shortened magnetosomes. The magnetic properties of magnetosomes are analysed and compared in DC and AC magnetic fields based on the evaluation of quasi-static hysteresis loops (energy losses) and calorimetric hyperthermia measurements (specific absorption rate), respectively. A sample of shortened magnetosomes behaves magnetically in a different manner, showing that both the energy loss and the specific absorption rate are reduced, and thereby indicates a variation in the heating process. The magnetic properties of magnetosomes, together with the new and stable geometry, are balanced, which opens the way for a better adaptation of the magnetic field parameters for particular applications.

  10. Effect of strain on low-loss electron energy loss spectra of group-III nitrides

    NASA Astrophysics Data System (ADS)

    Palisaitis, J.; Hsiao, C.-L.; Junaid, M.; Birch, J.; Hultman, L.; Persson, P. O. Å.

    2011-12-01

    Thin films of AlN experiencing different strain states were investigated with a scanning transmission electron microscope (STEM) by low-loss electron energy loss spectroscopy (EELS). The results conclude that the low-loss properties and in particular, the plasmon peak position is shifted as a direct consequence of the inherent strain of the sample. The results reveal that strain, even minor levels, can be measured by STEM-EELS. These results were further corroborated by full potential calculations and expanded to include the similar III nitrides GaN and InN. It is found that a unit-cell volume change of 1% results in a bulk plasmon peak shift of 0.159, 0.168, and 0.079 eV for AlN, GaN, and InN, respectively, according to simulations. The AlN peak shift was experimentally corroborated with a corresponding peak shift of 0.156 eV. The unit-cell volume is used here since it is found that regardless of in- and out-of-plane lattice augmentation, the low-loss properties appear near identical for constant volume. These results have an impact on the interpretation of the plasmon energy and its applicability for determining and separating stress and composition. It is found that while the bulk plasmon energy can be used as a measure of the composition in a group-III nitride alloy for relaxed structures, the presence of strain significantly affects such a measurement. The strain is found to have a lower impact on the peak shift for Al1-xInxN (˜3% compositional error per 1% volume change) and In1-xGaxN alloys compared to significant variations for Al1-xGaxN (16% compositional error for 1% volume change). Hence a key understanding in low-loss studies of III nitrides is that strain and composition are coupled and affect one another.

  11. Energy loss of fast clusters through matter

    SciTech Connect

    Ben-Hamu, D.; Baer, A.; Feldman, H.; Levin, J.; Heber, O.; Amitay, Z.; Vager, Z.; Zajfman, D.

    1997-12-01

    Energy loss in the MeV range of simple clusters impinging on thin carbon targets has been measured using a time-of-flight method. Stopping-power ratios defined as the ratio of the stopping power of the cluster to the sum of the stopping powers of the constituent atoms moving at the same velocity were investigated. Stopping- power ratios close to unity were observed for O{sub 2} and B{sub 3} clusters, while deenhancement effect is observed in the stopping-power ratios of C{sub 3} and C{sub 4}. The experimental results are compared both with an existing theoretical model, which takes into account the spatial correlation of the fragments, and with a simple united-atom model, which also includes the charge state evolution of the fragment ions inside the target. {copyright} {ital 1997} {ital The American Physical Society}

  12. Energy loss of coasting gold ions and deuterons in RHIC.

    SciTech Connect

    Abreu,N.; Blaskiewicz, M.; Brown, K.A.; Butler, J.J.; FischW; Harvey, M.; Tepikian, S.

    2008-06-23

    The total energy loss of coasting gold ion beams was measured at RHIC at two energies, corresponding to a gamma of 75.2 and 107.4. We describe the experiment and observations and compare the measured total energy loss with expectations from ionization losses at the residual gas, the energy loss due to impedance and synchrotron radiation. We find that the measured energy losses are below what is expected from free space synchrotron radiation. We believe that this shows evidence for suppression of synchrotron radiation which is cut off at long wavelength by the presence of the conducting beam pipe.

  13. Low Energy Electron-Impact Spectroscopy of C(sup 60) Buckminsterfullerene Molecule

    NASA Technical Reports Server (NTRS)

    Trajmar, S.; Wang, S.

    1993-01-01

    The methods of electron-impact spectroscopy were utilized to obtain the first low-energy, high-resolution energy-loss spectra of gas phase pure C(sub 60) and C(sub 60) + C(sub 70) mixture buckminsterfullerene molecules.

  14. Coherent parasitic energy loss of the recycler beam

    SciTech Connect

    K.Y. Ng

    2004-07-14

    Parasitic energy loss of the particle beam in the Recycler Ring is discussed. The long beam confined between two barrier waves has a spectrum that falls off rapidly with frequency. Discrete summation over the revolution harmonics must be made to obtain the correct energy loss per particle per turn, because only a few lower revolution harmonics of real part of the longitudinal impedance contribute to the parasitic energy loss. The longitudinal impedances of the broadband rf cavities, the broadband resistive-wall monitors, and the resistive wall of the vacuum chamber are discussed. They are the main sources of the parasitic energy loss.

  15. High resolution energy loss research: Si compounds and ceramics

    SciTech Connect

    Carpenter, R.W.; Lin, S.H.

    1992-01-01

    Our current investigation of the structure and chemistry of whisker/matrix interfaces and matrix grain boundaries in SiC whisker reinforced Si{sub 3}N{sub 4} composites has been completed. We examined these interfaces and boundaries in four composites whose starting materials and processing were identical except for the SiC whiskers themselves, which were from four different sources: American matrix, Nikkei, Huber and Tokai. Thus, differences in interfaces among the composites are attributable to differences in the whiskers. The results showed that oxygen-rich amorphous interfacial layers were discontinuous in all whisker/matrix interfaces and continuous in all matrix grain boundaries. Further, we used position-resolved high spatial resolution electron energy loss spectroscopy to show that the chemical interface width'' is much wider than the geometric or structural interface width'' at both types of interfaces in all four composites. The geometric interface widths were determined from high resolution transmission electron microscope images of edge-on interfaces.

  16. Interference effect in elastic parton energy loss in a finitemedium

    SciTech Connect

    Wang, Xin-Nian

    2005-04-18

    Similar to the radiative parton energy loss due to gluonbremsstrahlung, elastic energy loss of a parton undergoing multiplescattering in a finite medium is demonstrated to be sensitive tointerference effect. The interference between amplitudes of elasticscattering via a gluon exchange and that of gluon radiation reduces theeffective elastic energy loss in a finite medium and gives rise to anon-trivial length dependence. The reduction is most significant for apropagation length L<4/\\pi T in a medium with a temperature T. Thoughthe finite size effect is not significant for the average partonpropagation in the most central heavy-ion collisions, it will affect thecentrality dependence of its effect on jet quenching.

  17. Ethanol production: energy, economic, and environmental losses.

    PubMed

    Pimentel, David; Patzek, Tad; Cecil, Gerald

    2007-01-01

    The prime focus of ethanol production from corn is to replace the imported oil used in American vehicles, without expending more fossil energy in ethanol production than is produced as ethanol energy. In a thorough and up-to-date evaluation of all the fossil energy costs of ethanol production from corn, every step in the production and conversion process must be included. In this study, 14 energy inputs in average U.S. corn production are included. Then, in the fermentation/distillation operation, 9 more identified fossil fuel inputs are included. Some energy and economic credits are given for the by-products, including dried distillers grains (DDG). Based on all the fossil energy inputs, a total of 1.43 kcal fossil energy is expended to produced 1 kcal ethanol. When the energy value of the DDG, based on the feed value of the DDG as compared to that of soybean meal, is considered, the energy cost of ethanol production is reduced slightly, to 1.28 kcal fossil energy input per 1 kcal ethanol produced. Several proethanol investigators have overlooked various energy inputs in U.S. corn production, including farm machinery, processing machinery, and the use of hybrid corn. In other studies, unrealistic, low energy costs were attributed to such inputs as nitrogen fertilizer, insecticides, and herbicides. Controversy continues concerning the energy and economic credits that should be assigned to the by-products. The U.S. Department of Energy reports that 17.0 billion L ethanol was produced in 2005. This represents only less than 1% of total oil use in the U.S. These yields are based on using about 18% of total U.S. corn production and 18% of cornland. Because the production of ethanol requires large inputs of both oil and natural gas in production, the U.S. is importing both oil and natural gas to produce ethanol. Furthermore, the U.S. Government is spending about dollar 3 billion annually to subsidize ethanol production, a subsidy of dollar 0.79/L ethanol produced. With

  18. Energy-loss rate of a fast particle in graphene

    SciTech Connect

    Ang, Yee Sin; Zhang, C.; Kee, Chun Yun

    2011-08-01

    The energy-loss rate of a fast particle in graphene is studied. The energy-loss rate always increases with increasing incident particle energy, which is quite unusual when compared to electron gas in normal metal. Graphene exhibits a ''discriminating'' behavior where there exists a low energy cut-off below which the scattering process is strictly forbidden, leading to lossless traverse of an external particle in graphene. This low energy cutoff is of the order of nearest neighbor hopping bandwidth. Our results suggest that backscattering is also absent in the external particle scattering of graphene.

  19. Theory of photoelectron production, transport and energy loss

    NASA Technical Reports Server (NTRS)

    Nagy, A. F.

    1974-01-01

    Current understanding of the theory of ionospheric photoelectron production, transport and energy loss is summarized. The various approaches used in the theoretical calculations of photoelectron fluxes appear to be self consistent and sound; improved values for a number of input parameters are needed now in order to achieve significant improvements and more confidence in the results. The major remaining problem in the present day theory of photoelectron transport and energy loss is centered around the calculations of photoelectron transit through the protonosphere.

  20. Energy loss by resonance line photons in an absorbing medium

    NASA Technical Reports Server (NTRS)

    Hummer, D. G.; Kunasz, P. B.

    1980-01-01

    The mean path length of photons undergoing repeated scatterings in media of large optical thickness is calculated from accurate numerical solutions of the transfer equation including the effect of frequency redistribution characteristic of combined Doppler and natural broadening. Energy loss by continuous absorption processes, such as ionization or dust absorption, is discussed, and asymptotic scaling laws for the energy loss, the mean path length, and the mean number of scatterings are inferred from the numerical data.

  1. Heat Loss Experiments: Teach Energy Savings with Cardboard "House"

    ERIC Educational Resources Information Center

    Roman, Harry T.

    2011-01-01

    Using two cardboard boxes, a light bulb socket, light bulbs of varying wattage, a thermometer, and some insulation, students can learn some interesting lessons about how heat loss occurs in homes. This article describes practical experiments that work well on units related to energy, sustainable energy, renewables, engineering, and construction.…

  2. Estimating convective energy losses from solar central receivers

    SciTech Connect

    Siebers, D L; Kraabel, J S

    1984-04-01

    This report outlines a method for estimating the total convective energy loss from a receiver of a solar central receiver power plant. Two types of receivers are considered in detail: a cylindrical, external-type receiver and a cavity-type receiver. The method is intended to provide the designer with a tool for estimating the total convective energy loss that is based on current knowledge of convective heat transfer from receivers to the environment and that is adaptable to new information as it becomes available. The current knowledge consists of information from two recent large-scale experiments, as well as information already in the literature. Also outlined is a method for estimating the uncertainty in the convective loss estimates. Sample estimations of the total convective energy loss and the uncertainties in those convective energy loss estimates for the external receiver of the 10 MWe Solar Thermal Central Receiver Plant (Barstow, California) and the cavity receiver of the International Energy Agency Small Solar Power Systems Project (Almeria, Spain) are included in the appendices.

  3. Zero kinetic energy photoelectron spectroscopy of triphenylene

    NASA Astrophysics Data System (ADS)

    Harthcock, Colin; Zhang, Jie; Kong, Wei

    2014-06-01

    We report vibrational information of both the first electronically excited state and the ground cationic state of jet-cooled triphenylene via the techniques of resonantly enhanced multiphoton ionization (REMPI) and zero kinetic energy (ZEKE) photoelectron spectroscopy. The first excited electronic state S1 of the neutral molecule is of A1' symmetry and is therefore electric dipole forbidden in the D3h group. Consequently, there are no observable Franck-Condon allowed totally symmetric a1' vibrational bands in the REMPI spectrum. All observed vibrational transitions are due to Herzberg-Teller vibronic coupling to the E' third electronically excited state S3. The assignment of all vibrational bands as e' symmetry is based on comparisons with calculations using the time dependent density functional theory and spectroscopic simulations. When an electron is eliminated, the molecular frame undergoes Jahn-Teller distortion, lowering the point group to C2v and resulting in two nearly degenerate electronic states of A2 and B1 symmetry. Here we follow a crude treatment by assuming that all e' vibrational modes resolve into b2 and a1 modes in the C2v molecular frame. Some observed ZEKE transitions are tentatively assigned, and the adiabatic ionization threshold is determined to be 63 365 ± 7 cm-1. The observed ZEKE spectra contain a consistent pattern, with a cluster of transitions centered near the same vibrational level of the cation as that of the intermediate state, roughly consistent with the propensity rule. However, complete assignment of the detailed vibrational structure due to Jahn-Teller coupling requires much more extensive calculations, which will be performed in the future.

  4. Energy-Efficiency Options for Insurance Loss Prevention

    SciTech Connect

    Mills, E.; Knoepfel, I.

    1997-06-09

    Energy-efficiency improvements offer the insurance industry two areas of opportunity: reducing ordinary claims and avoiding greenhouse gas emissions that could precipitate natural disaster losses resulting from global climate change. We present three vehicles for taking advantage of this opportunity, including research and development, in- house energy management, and provision of key information to insurance customers and risk managers. The complementary role for renewable energy systems is also introduced.

  5. Energy loss in unstable quark-gluon plasma

    NASA Astrophysics Data System (ADS)

    Carrington, Margaret E.; Deja, Katarzyna; Mrówczyński, Stanisław

    2015-10-01

    The momentum distribution of quark-gluon plasma at the early stage of a relativistic heavy-ion collision is anisotropic; consequently, the system, which is assumed to be weakly coupled, is unstable owing to chromomagnetic plasma modes. We consider a high-energy parton which flies across such an unstable plasma, and the energy transfer between the parton and the medium is studied as an initial value problem. In the case of equilibrium plasmas, the well-known formula of collisional energy loss is reproduced. The unstable plasma case is much more complex, and the parton can lose or gain energy depending on the initial conditions. The extremely prolate and extremely oblate systems are considered as examples of unstable plasmas, and two classes of initial conditions are discussed. When the initial chromodynamic field is uncorrelated with the color state of the parton, it typically looses energy, and the magnitude of the energy loss is comparable to that in an equilibrium plasma of the same density. When the initial chromodynamic field is induced by the parton, it can be either accelerated or decelerated depending on the relative phase factor. With a correlated initial condition, the energy transfer grows exponentially in time and its magnitude can much exceed the absolute value of energy loss in an equilibrium plasma. The energy transfer is also strongly directionally dependent. Consequences of our findings for the phenomenology of jet quenching in relativistic heavy-ion collisions are briefly discussed.

  6. Effect of physical activity on weight loss, energy expenditure and energy intake during diet induced weight loss

    PubMed Central

    DeLany, James P.; Kelley, David E.; Hames, Kazanna C.; Jakicic, John M.; Goodpaster, Bret H.

    2016-01-01

    Objective Objective measurements of physical activity (PA), energy expenditure (EE) and energy intake can provide valuable information regarding appropriate strategies for successful sustained weight loss. Design and methods We examined total EE by doubly labeled water, resting metabolic rate, PA with activity monitors, and energy intake by the Intake/Balance technique in 116 severely obese undergoing intervention with diet alone (DO) or diet plus PA (D-PA). Results Weight loss of 9.6±6.8 kg resulted in decreased EE which was not minimized in the D-PA group. Comparing the highest and lowest quartiles of increase in PA revealed a lower decrease in TDEE (−122±319 vs. −376±305 kcal/d), elimination of the drop in AEE (83±279 vs. −211±284 kcal/d) and greater weight loss (13.0±7.0 vs. 8.1±6.3 kg). Increased PA was associated with greater adherence to energy restriction and maintenance of greater weight loss during months 7–12. Conclusion Noncompliance to prescribed PA in the DO and D-PA groups partially masked the effects of PA to increase weight loss and to minimize the reduced EE. Increased PA was also associated with improved adherence to prescribed caloric restriction. A strong recommendation needs to be made to improve interventions that promote PA within the context of behavioral weight loss interventions. PMID:23804562

  7. An electron energy-loss study of picene and chrysene based charge transfer salts

    SciTech Connect

    Müller, Eric; Mahns, Benjamin; Büchner, Bernd; Knupfer, Martin

    2015-05-14

    The electronic excitation spectra of charge transfer compounds built from the hydrocarbons picene and chrysene, and the strong electron acceptors F{sub 4}TCNQ (2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane) and TCNQ (7,7,8,8-tetracyanoquinodimethan) have been investigated using electron energy-loss spectroscopy. The corresponding charge transfer compounds have been prepared by co-evaporation of the pristine constituents. We demonstrate that all investigated combinations support charge transfer, which results in new electronic excitation features at low energy. This might represent a way to synthesize low band gap organic semiconductors.

  8. Measurement of the nuclear energy loss under channeling

    NASA Astrophysics Data System (ADS)

    Winter, H.; Mertens, A.

    2001-07-01

    Neutral Ne atoms with keV energies are scattered under channeling conditions, i.e. at a glancing angle of incidence, from a LiF(001) surface. By means of a time-of-flight method with a pulsed neutral beam we record energy distributions for scattered projectiles. For this specific system the small energy transferred to the crystal lattice ("nuclear energy loss") during channeling via binary collisions with large impact parameters dominates the dissipation of projectile energy. All other excitations of the solid can be brought to a negligible level.

  9. Simulation of electron energy loss spectra of nanomaterials with linear-scaling density functional theory.

    PubMed

    Tait, E W; Ratcliff, L E; Payne, M C; Haynes, P D; Hine, N D M

    2016-05-18

    Experimental techniques for electron energy loss spectroscopy (EELS) combine high energy resolution with high spatial resolution. They are therefore powerful tools for investigating the local electronic structure of complex systems such as nanostructures, interfaces and even individual defects. Interpretation of experimental electron energy loss spectra is often challenging and can require theoretical modelling of candidate structures, which themselves may be large and complex, beyond the capabilities of traditional cubic-scaling density functional theory. In this work, we present functionality to compute electron energy loss spectra within the onetep linear-scaling density functional theory code. We first demonstrate that simulated spectra agree with those computed using conventional plane wave pseudopotential methods to a high degree of precision. The ability of onetep to tackle large problems is then exploited to investigate convergence of spectra with respect to supercell size. Finally, we apply the novel functionality to a study of the electron energy loss spectra of defects on the (1 0 1) surface of an anatase slab and determine concentrations of defects which might be experimentally detectable. PMID:27094207

  10. Simulation of electron energy loss spectra of nanomaterials with linear-scaling density functional theory

    NASA Astrophysics Data System (ADS)

    Tait, E. W.; Ratcliff, L. E.; Payne, M. C.; Haynes, P. D.; Hine, N. D. M.

    2016-05-01

    Experimental techniques for electron energy loss spectroscopy (EELS) combine high energy resolution with high spatial resolution. They are therefore powerful tools for investigating the local electronic structure of complex systems such as nanostructures, interfaces and even individual defects. Interpretation of experimental electron energy loss spectra is often challenging and can require theoretical modelling of candidate structures, which themselves may be large and complex, beyond the capabilities of traditional cubic-scaling density functional theory. In this work, we present functionality to compute electron energy loss spectra within the onetep linear-scaling density functional theory code. We first demonstrate that simulated spectra agree with those computed using conventional plane wave pseudopotential methods to a high degree of precision. The ability of onetep to tackle large problems is then exploited to investigate convergence of spectra with respect to supercell size. Finally, we apply the novel functionality to a study of the electron energy loss spectra of defects on the (1 0 1) surface of an anatase slab and determine concentrations of defects which might be experimentally detectable.

  11. Energy loss of charged particles colliding with an oscillator

    NASA Astrophysics Data System (ADS)

    Makarov, D. N.

    2015-04-01

    Energy loss of fast charged particles colliding with an oscillator is considered in the dipole approximation. In this approximation, the problem is solved exactly and the energy loss of the oscillator from the initial state | m> = |0> is found in the form of the sum of single integrals. It is shown that passing to the limit, the Bethe theory for an atom with small perturbations can be obtained, and in the case of strong fields, the correction to the Bethe theory, analogous to the Bloch correction, can be calculated; in addition, a classical limit coinciding with the Bohr formula is possible.

  12. Energy loss of correlated ions in dense plasma

    NASA Astrophysics Data System (ADS)

    Ahmed, Baida Muhsen; Ahmed, Khalid A.; Ahmed, Riayhd Khalil

    2016-05-01

    The interaction between proton clusters and plasma gas is studied using the dielectric function by fried-conte formalism. The theoretical formula of the potential basis equation derived and the energy loss of incident proton (point-like, correlate and dicluster) with different parameters (velocity, distance, densities and temperatures) is calculated numerically. Two different equations were used to enhance the correlation stopping (ECS), it is clear that the present results are consistent with the dielectric calculation of energy loss at parameters ne = 1017cm-3 and T = (2 - 10) eV. The result showed a good correlation with the previous work.

  13. Paths and ionization losses of proton energy in different substances

    SciTech Connect

    Vasilovskiy, I.M.; Karpov, I.I.; Petrukhin, V.I.; Prokoshkin, Yu.D.

    1986-02-14

    Ionization energy losses of charged particles in a substance are described by the well-known Bethe-Bloch formula. However, the magnitudes of the ionization potentials in region of low proton energies (E < 100 MeV) for heavy elements prove to be considerably larger than those at high energies. Thus, studies of ionization losses in the region of high energies are the main source of the experimental information necessary for the correction of the Bethe-Bloch formula and determination of magnitudes of ionization potentials I. The purpose of this work was to measure the magnitudes of ionization losses dE/ds, paths R and ionization potentials I at a proton energy of E 670 MeV. The measurements were taken by the relative method for different substances of x, and the magnitudes of q sub x=(dE/ds) sub x/(dE/ds) sub Al and px=R sub x/R sub Al were found. Quantities qx and px weakly depend on the energy E where at E=200-600 MeV, a=(2-4).10-2 for different substances. The proton energy was determined with an accuracy of 2 MeV.

  14. Evolution effects on parton energy loss with detailed balance

    SciTech Connect

    Cheng Luan; Wang Enke

    2010-07-15

    The initial conditions in the chemically nonequilibrated medium and Bjorken expanding medium at Relativistic Heavy Ion Collider (RHIC) are determined. With a set of rate equations describing the chemical equilibration of quarks and gluons based on perturbative QCD, we investigate the consequence for parton evolution at RHIC. With considering parton evolution, it is shown that the Debye screening mass and the inverse mean free-path of gluons reduce with increasing proper time in the QGP medium. The parton evolution affects the parton energy loss with detailed balance, both parton energy loss from stimulated emission in the chemically nonequilibrated expanding medium and in Bjorken expanding medium are linear dependent on the propagating distance rather than square dependent in the static medium. The energy absorption cannot be neglected at intermediate jet energies and small propagating distance of the energetic parton in contrast with that it is important only at intermediate jet energy in the static medium. This will increase the energy and propagating distance dependence of the parton energy loss and will affect the shape of suppression of moderately high P{sub T} hadron spectra.

  15. Modeling energy-loss spectra due to phonon excitation

    NASA Astrophysics Data System (ADS)

    Forbes, B. D.; Allen, L. J.

    2016-07-01

    We discuss a fundamental theory of how to calculate the phonon-loss sector of the energy-loss spectrum for electrons scattering from crystalline solids. A correlated model for the atomic motion is used for calculating the vibrational modes. Spectra are calculated for crystalline silicon illuminated by a plane wave and by an atomic-scale focused coherent probe, in which case the spectra depend on probe position. These spectra are also affected by the size of the spectrometer aperture. The correlated model is contrasted with the Einstein model in which atoms in the specimen are assumed to vibrate independently. We also discuss how both the correlated and Einstein models relate to a classical view of the energy-loss process.

  16. Energy loss of 132Xe-ions in thin foils

    NASA Astrophysics Data System (ADS)

    Trzaska, W. H.; Knyazheva, G. N.; Perkowski, J.; Andrzejewski, J.; Khlebnikov, S. V.; Kozulin, E. M.; Lyapin, V. G.; Malkiewicz, T.; Mutterer, M.

    2009-10-01

    The energy loss of 132Xe-ions in C, Al, Ni, Ag, Lu, Au, Pb and Th foils was measured in the energy range from 0.1 to 5 MeV/u using the TOF-E method. The results are compared with previously published data and with the predictions of several computer codes. They include theoretical codes: PASS, CASP, semi-empirical programs: SRIM, LET and the Hubert table predictions.

  17. Rotating gravity currents. Part 1. Energy loss theory

    NASA Astrophysics Data System (ADS)

    Martin, J. R.; Lane-Serff, G. F.

    2005-01-01

    A comprehensive energy loss theory for gravity currents in rotating rectangular channels is presented. The model is an extension of the non-rotating energy loss theory of Benjamin (J. Fluid Mech. vol. 31, 1968, p. 209) and the steady-state dissipationless theory of rotating gravity currents of Hacker (PhD thesis, 1996). The theory assumes the fluid is inviscid, there is no shear within the current, and the Boussinesq approximation is made. Dissipation is introduced using a simple method. A head loss term is introduced into the Bernoulli equation and it is assumed that the energy loss is uniform across the stream. Conservation of momentum, volume flux and potential vorticity between upstream and downstream locations is then considered. By allowing for energy dissipation, results are obtained for channels of arbitrary depth and width (relative to the current). The results match those from earlier workers in the two limits of (i) zero rotation (but including dissipation) and (ii) zero dissipation (but including rotation). Three types of flow are identified as the effect of rotation increases, characterized in terms of the location of the outcropping interface between the gravity current and the ambient fluid on the channel boundaries. The parameters for transitions between these cases are quantified, as is the detailed behaviour of the flow in all cases. In particular, the speed of the current can be predicted for any given channel depth and width. As the channel depth increases, the predicted Froude number tends to surd 2, as for non-rotating flows.

  18. Energy Drinks, Weight Loss, and Disordered Eating Behaviors

    ERIC Educational Resources Information Center

    Jeffers, Amy J.; Vatalaro Hill, Katherine E.; Benotsch, Eric G.

    2014-01-01

    Objective: The present study examined energy drink consumption and relations with weight loss attempts and behaviors, body image, and eating disorders. Participants/Methods: This is a secondary analysis using data from 856 undergraduate students who completed the American College Health Association-National College Health Assessment II…

  19. Two Theorems on Dissipative Energy Losses in Capacitor Systems

    ERIC Educational Resources Information Center

    Newburgh, Ronald

    2005-01-01

    This article examines energy losses in charge motion in two capacitor systems. In the first charge is transferred from a charged capacitor to an uncharged one through a resistor. In the second a battery charges an originally uncharged capacitor through a resistance. Analysis leads to two surprising general theorems. In the first case the fraction…

  20. Uncertainty, loss aversion, and markets for energy efficiency

    SciTech Connect

    Greene, David L

    2010-01-01

    Increasing energy efficiency is critical to mitigating greenhouse gas emissions from fossil-fuel combustion, reducing oil dependence, and achieving a sustainable global energy system. The tendency of markets to neglect apparently cost-effective energy efficiency options has been called the efficiency gap or energy paradox. The market for energy efficiency in new, energy-using durable goods, however, appears to have a bias that leads to undervaluation of future energy savings relative to their expected value. This paper argues that the bias is chiefly produced by the combination of substantial uncertainty about the net value of future fuel savings and the loss aversion of typical consumers. This framework relies on the theory of contextdependent preferences. The uncertainty-loss aversion bias against energy efficiency is quantifiable, making it potentially correctible by policy measures. The welfare economics of such policies remains unresolved. Data on the costs of increased fuel economy of new passenger cars, taken from a National Research Council study, illustrate how an apparently cost-effective increase in energy efficiency would be uninteresting to lossaverse consumers.

  1. High resolution energy loss research: Si compound ceramics and composites. [1990 annual progress report

    SciTech Connect

    Carpenter, R W; Lin, S H

    1990-12-31

    This report discusses proposed work on silicon compound ceramics and composites. High resolution composition and structure analysis of interfaces in ceramic and metal matrix composites and certain grain boundaries in silicon and its interfaces with oxides and nitrides is proposed. Composition and bonding analysis will be done with high spatial resolution (20 Angstroms or better) parallel electron energy loss spectroscopy using a field emission analytical electron microscope. Structural analysis will be done at the 1.8 Angstrom resolution level at 200kV by HREM. Theoretical electron energy loss cross section computations will be used to interpret electronic structure of these materials. Both self-consistent field MO and multiple scattering computational methods are being done and evaluated.

  2. Scaled Energy Spectroscopy of Collisionally Perturbed Potassium Rydberg States

    NASA Astrophysics Data System (ADS)

    Keeler, Matthew Len; Setzer, William

    2010-03-01

    We will present preliminary results on the recurrence spectroscopy (or scaled energy spectroscopy) of highly-excited potassium in the presence of collisional perturbations. Recurrence spectroscopy, with the aid of closed orbit theory, has produced useful insights into the semi-classical description of non-hydrogenic spectral features of excited atoms in external fields. We demonstrate how to apply recurrence spectroscopy to the Stark spectrum of potassium subject to collisional line-shift and line-broadening. When krypton gas is added to the system the absorption spectrum experiences line broadening, differential line shifts, and state mixing. With an appropriately modified energy scale, perturbations of the absorption spectrum become meaningful features within the scaled-energy spectrum. New features found within the recurrence spectra can then, with semi-classical closed orbit theory, be interpreted in terms of classical decoherence, elastic and inelastic collisions.

  3. Precise measurements of the energy losses of heavy ions

    SciTech Connect

    Bichsel, H.; Hiraoka, T. |

    1995-12-31

    Accurate measurements of the energy loss of all charged particles are needed to determine the reliability of the Bethe theory of stopping power. Few measurements have been made for particles with energies greater than 20 MeV/u. A first step to accurate measurements is to establish the precision of an experimental method. The authors report here about the recent energy loss measurements for 290 MeV/u carbon ions from the HIMAC. They have been made with the method used for 70 MeV protons. The ion beam traverses an absorber of thickness t and the residual range of the ions is measured with a water container of adjustable thickness (``range gauge``).

  4. Energy Losses Estimation During Pulsed-Laser Seam Welding

    NASA Astrophysics Data System (ADS)

    Sebestova, Hana; Havelkova, Martina; Chmelickova, Hana

    2014-06-01

    The finite-element tool SYSWELD (ESI Group, Paris, France) was adapted to simulate pulsed-laser seam welding. Besides temperature field distribution, one of the possible outputs of the welding simulation is the amount of absorbed power necessary to melt the required material volume including energy losses. Comparing absorbed or melting energy with applied laser energy, welding efficiencies can be calculated. This article presents achieved results of welding efficiency estimation based on the assimilation both experimental and simulation output data of the pulsed Nd:YAG laser bead on plate welding of 0.6-mm-thick AISI 304 stainless steel sheets using different beam powers.

  5. Aromatic Polyurea Possessing High Electrical Energy Density and Low Loss

    NASA Astrophysics Data System (ADS)

    Thakur, Yash; Lin, Minren; Wu, Shan; Zhang, Q. M.

    2016-07-01

    We report the development of a dielectric polymer, poly (ether methyl ether urea) (PEMEU), which possesses a dielectric constant of 4 and is thermally stable up to 150°C. The experimental results show that the ether units are effective in softening the rigid polymer and making it thermally processable, while the high dipole moment of urea units and glass structure of the polymer leads to a low dielectric loss and low conduction loss. As a result, PEMEU high quality thin films can be fabricated which exhibit exceptionally high breakdown field of >1.5 GV/m, and a low conduction loss at fields up to the breakdown. Consequently, the PEMEU films exhibit a high charge-discharge efficiency of 90% and a high discharged energy density of 36 J/cm3.

  6. Suppression and energy loss in Quark-Gluon Plasma

    NASA Astrophysics Data System (ADS)

    Djordjevic, M.

    2016-01-01

    High momentum suppression of light and heavy flavor observables is considered to be an excellent probe of jet-medium interactions in QCD matter created at RHIC and LHC. Utilizing this tool requires accurate suppression predictions for different experiments, probes and experimental conditions, and their unbiased comparison with experimental data. We developed the dynamical energy loss formalism which takes into account both radiative and collision energy loss computed within the same theoretical framework, dynamical (as opposed to static) scattering centers, finite magnetic mass, running coupling and uses no free parameters in comparison with experimental data. Within this formalism, we provide predictions, and a systematic comparison with the experimental data, for a diverse set of probes, various centrality ranges and various collision energies at RHIC and LHC. We also provide clear qualitative and quantitative predictions for the upcoming LHC experiments. A comprehensive agreement between our predictions and experimental results suggests that our dynamical energy loss formalism can well explain the jet-medium interactions in QGP, which will be further tested by the obtained predictions for the upcoming data.

  7. Energy loss analysis of an integrated space power distribution system

    NASA Technical Reports Server (NTRS)

    Kankam, M. D.; Ribeiro, P. F.

    1992-01-01

    The results of studies related to conceptual topologies of an integrated utility-like space power system are described. The system topologies are comparatively analyzed by considering their transmission energy losses as functions of mainly distribution voltage level and load composition. The analysis is expedited by use of a Distribution System Analysis and Simulation (DSAS) software. This recently developed computer program by the Electric Power Research Institute (EPRI) uses improved load models to solve the power flow within the system. However, present shortcomings of the software with regard to space applications, and incompletely defined characteristics of a space power system make the results applicable to only the fundamental trends of energy losses of the topologies studied. Accountability, such as included, for the effects of the various parameters on the system performance can constitute part of a planning tool for a space power distribution system.

  8. Collisional energy loss above the critical temperature in QCD

    NASA Astrophysics Data System (ADS)

    Lin, Shu; Pisarski, Robert D.; Skokov, Vladimir V.

    2014-03-01

    We compute the collisional energy loss for a heavy quark above the critical temperature in Quantum ChromoDynamics (QCD). We work in the semi Quark-Gluon Plasma, which assumes that this region is dominated by the non-trivial holonomy of the thermal Wilson line. Relative to the result of leading order in perturbation theory, at a fixed value of the coupling constant we generically find that collisional energy loss is suppressed by powers of the Polyakov loop, l<1. For small values of the loop, this suppression is linear when the heavy quark scatters off of light quarks, and quadratic when the heavy quark scatters off of gluons, or for Compton scattering.

  9. Theoretical interpretation of electron energy-loss spectroscopic images

    DOE PAGESBeta

    Allen, L. J.; D'Alfonso, Adrian J.; Findlay, Scott D.; Oxley, Mark P.; Bosman, M.; Keast, V. J.; Cossgriff, E. C.; Behan, G.; Nellist, P. D.; Kirkland, Angus I.

    2008-04-10

    In this paper, we discuss the theory of electron energy-loss spectroscopic images in scanning transmission electron microscopy. Three case studies are presented which have as common themes issues of inelastic scattering, coherence and image interpretation. The first is a state-by-state inelastic transitions analysis of a spectroscopic image which does not admit direct visual interpretation. The second compares theory and experiment for two-dimensional mapping. Finally, the third considers imaging in three dimensions via depth sectioning.

  10. Very Low Energy Supernovae From Neutrino Mass Loss

    NASA Astrophysics Data System (ADS)

    Lovegrove, Elizabeth; Woosley, S. E.

    2013-01-01

    The continuing difficulty of achieving a reliable core-collapse supernova in simulation has led many to speculate about what transients might be visible if a core-collapse supernova fails. If some percentage of such supernovae fail, there may be many more types of transients occurring than are currently being detected and catalogued as supernovae. Even if the original outgoing shock in a collapsing presupernova star fails, one must still consider the hydrodynamic response of the star to the abrupt loss of a small amount of mass via neutrinos as the core forms a protoneutron star. Following a suggestion by Nadezhin (1980), we use the Kepler and CASTRO codes to model the hydrodynamical responses of typical supernova progenitor stars to the loss of approximately 0.2 - 0.5 solar masses of gravitational mass from their centers. In a red supergiant star, a very weak supernova with total kinetic energy ~1047 ergs results. The binding energy of the hydrogen envelope before the explosion is of the same order and, depending upon assumptions regarding the neutrino loss rates, most of it is ejected. Ejection speeds are ~50 km/s and luminosities ~1039 ergs/s are maintained for about a year. A significant part of the energy comes from the recombination of hydrogen. The color of the explosion is extremely red and the events bear some similarity to the detected transients catalogued as "luminous red novae."

  11. Proton Nonionizing Energy Loss (NIEL) for Device Applications

    NASA Technical Reports Server (NTRS)

    Jun, Insoo; Xapsos, Michael A.; Messenger, Scott R.; Burke, Edward A.; Walters, Robert J.; Summers, Geoff; Jordan, Thomas

    2003-01-01

    Nonionizing energy loss (NIEL) is a quantity that describes the rate of energy loss due to atomic displacements as a particle traverses a material. The product of the NIEL and the particle fluence (time integrated flux) gives the displacement damage energy deposition per unit mass of material. NIEL plays the same role to the displacement damage energy deposition as the stopping power to the total ionizing dose (TID). The concept of NIEL has been very useful for correlating particle induced displacement damage effects in semiconductor and optical devices. Many studies have successfully demonstrated that the degradation of semiconductor devices or optical sensors in a radiation field can be linearly correlated to the displacement damage energy, and subsequently to the NIEL deposited in the semiconductor devices or optical sensors. In addition, the NIEL concept was also useful in the study of both Si and GaAs solar cells and of high temperature superconductors, and at predicting the survivability of detectors used at the LHC at CERN. On the other hand, there are some instances where discrepancies are observed in the application of NIEL, most notably in GaAs semiconductor devices. However, NIEL is still a valuable tool, and can be used to scale damages produced by different particles and in different environments, even though this is not understood at the microscopic level.

  12. Energy loss of ions implanted in MOS dielectric films

    NASA Astrophysics Data System (ADS)

    Shyam, Radhey

    Energy loss measurements of ions in the low kinetic energy regime have been made on as-grown SiO2(170-190nm) targets. Singly charged Na + ions with kinetic energies of 2-5 keV and highly charged ions Ar +Q (Q=4, 8 and 11) with a kinetic energy of 1 keV were used. Excitations produced by the ion energy loss in the oxides were captured by encapsulating the irradiated oxide under a top metallic contact. The resulting Metal-Oxide-Semiconductor (MOS) devices were probed with Capacitance-Voltage (C V) measurements and extracted the flatband voltages from the C-V curves. The C-V results for singly charged ion experiments reveal that the changes in the flatband voltage and slope for implanted devices relative to the pristine devices can be used to delineate effects due to implanted ions only and ion induced damage. The data shows that the flatband voltage shifts and C-V slope changes are energy dependent. The observed changes in flatband voltage which are greater than those predicted by calculations scaled for the ion dose and implantation range (SRIM). These results, however, are consistent with a columnar recombination model, where electron-hole pairs are created due to the energy deposited by the implanted ions within the oxide. The remaining holes left after recombination losses are diffused through the oxide at the room temperature and remain present as trapped charges. Comparison of the data with the total number of the holes generated gives a fractional yield of 0.0124 which is of the same order as prior published high energy irradiation experiments. Additionally, the interface trap density, extracted from high and low frequency C-V measurements is observed to increase by one order of magnitude over our incident beam energy. These results confirm that dose- and kinetic energy -dependent effects can be recorded for singly charged ion irradiation on oxides using this method. Highly charged ion results also confirm that dose as well as and charge-dependent effects can

  13. Muon energy loss at high energy and implications for detector design

    SciTech Connect

    Eastman, J.J.; Loken, S.C.

    1987-11-01

    We study the effects of energy loss and associated electromagnetic showers on muon tracking and momentum measurement in muon detectors operating in the energy range 100 GeV-5 TeV. A detailed Monte Carlo simulation tracks muons and shower particles through a detector structure and evaluates the charged-particle environment in chambers. We find that catastrophic energy loss events accompanied by energetic showers can pose serious problems to designers of muon spectrometers. 14 refs., 6 figs.

  14. Low energy nuclear spin excitations in Ho metal investigated by high resolution neutron spectroscopy.

    PubMed

    Chatterji, Tapan; Jalarvo, Niina

    2013-04-17

    We have investigated the low energy excitations in metallic Ho by high resolution neutron spectroscopy. We found at T = 3 K clear inelastic peaks in the energy loss and energy gain sides, along with the central elastic peak. The energy of this low energy excitation, which is 26.59 ± 0.02 μeV at T = 3 K, decreased continuously and became zero at TN ≈ 130 K. By fitting the data in the temperature range 100-127.5 K with a power law we obtained the power-law exponent β = 0.37 ± 0.02, which agrees with the expected value β = 0.367 for a three-dimensional Heisenberg model. Thus the energy of the low energy excitations can be associated with the order parameter. PMID:23507905

  15. Energy-gap spectroscopy of superconductors using a tunneling microscope

    NASA Technical Reports Server (NTRS)

    Le Duc, H. G.; Kaiser, W. J.; Stern, J. A.

    1987-01-01

    A unique scanning tunneling microscope (STM) system has been developed for spectroscopy of the superconducting energy gap. High-resolution control of tunnel current and voltage allows for measurement of superconducting properties at tunnel resistance levels 100-1000 greater than that achieved in prior work. The previously used STM methods for superconductor spectroscopy are compared to those developed for the work reported here. Superconducting energy-gap spectra are reported for three superconductors, Pb, PbBi, and NbN, over a range of tunnel resistance. The measured spectra are compared directly to theory.

  16. Losses of ion energy in the multicomponent beam

    NASA Astrophysics Data System (ADS)

    Gasanov, Ilkham S.; Gurbanov, Ilgar I.; Akbarov, Elchin M.

    2015-03-01

    Energy losses of near axis ions and decreases in ion current density in the center of a beam were observed in a liquid metal source operating under a charged nanodroplets (In, Sn, Au, Ge) generation regime. In experiments, nanodroplets with the sizes of 2-20 nanometers and a characteristic specific charge of 5 × 104 C/kg were revealed. Energy spectra of ions were defined by means of the filter of speeds with cross-section static electromagnetic fields. A reduction of 4% of the In+ ions energy was observed under the conditions of the curried out measurements. The stream of nanoparticles, in contrast to an ion beam, has a small radial divergence; outside of this stream, change of ion speeds is not observed. Energy losses of ions occur during their flight through small nanoparticles. Penetration depth of the accelerated ions in liquid indium is estimated within the framework of the Lindhard-Scharff-Schiott model. Similar interaction between components occurs in ion-beam systems of complex composition where there is a relative movement of various charged particles.

  17. High Q diamond hemispherical resonators: fabrication and energy loss mechanisms

    NASA Astrophysics Data System (ADS)

    Bernstein, Jonathan J.; Bancu, Mirela G.; Bauer, Joseph M.; Cook, Eugene H.; Kumar, Parshant; Newton, Eric; Nyinjee, Tenzin; Perlin, Gayatri E.; Ricker, Joseph A.; Teynor, William A.; Weinberg, Marc S.

    2015-08-01

    We have fabricated polycrystalline diamond hemispheres by hot-filament CVD (HFCVD) in spherical cavities wet-etched into a high temperature glass substrate CTE matched to silicon. Hemispherical resonators 1.4 mm in diameter have a Q of up to 143 000 in the fundamental wineglass mode, for a ringdown time of 2.4 s. Without trimming, resonators have the two degenerate wineglass modes frequency matched as close as 2 Hz, or 0.013% of the resonant frequency (~16 kHz). Laser trimming was used to match resonant modes on hemispheres to 0.3 Hz. Experimental and FEA energy loss studies on cantilevers and hemispheres examine various energy loss mechanisms, showing that surface related losses are dominant. Diamond cantilevers with a Q of 400 000 and a ringdown time of 15.4 s were measured, showing the potential of polycrystalline diamond films for high Q resonators. These resonators show great promise for use as hemispherical resonant gyroscopes (HRGs) on a chip.

  18. Elastic energy loss and longitudinal straggling of a hard jet

    SciTech Connect

    Majumder, A.

    2009-09-15

    The elastic energy loss encountered by jets produced in deep-inelastic scattering (DIS) off a large nucleus is studied in the collinear limit. In close analogy to the case of (nonradiative) transverse momentum broadening, which is dependent on the medium transport coefficient q, a class of medium enhanced higher twist operators which contribute to the nonradiative loss of the forward light-cone momentum of the jet (q{sup -}) are identified and the leading correction in the limit of asymptotically high q{sup -} is isolated. Based on these operator products, a new transport coefficient e is motivated which quantifies the energy loss per unit length encountered by the hard jet. These operator products are then computed, explicitly, in the case of a similar hard jet traversing a deconfined quark-gluon plasma (QGP) in the hard-thermal-loop (HTL) approximation. This is followed by an evaluation of subleading contributions which are suppressed by the inverse light-cone momentum q{sup -}, which yields the longitudinal 'straggling', i.e., a slight change in light cone momentum due to the Brownian propagation through a medium with a fluctuating color field.

  19. Energy loss in a partonic transport model including bremsstrahlung processes

    SciTech Connect

    Fochler, Oliver; Greiner, Carsten; Xu Zhe

    2010-08-15

    A detailed investigation of the energy loss of gluons that traverse a thermal gluonic medium simulated within the perturbative QCD-based transport model BAMPS (a Boltzmann approach to multiparton scatterings) is presented in the first part of this work. For simplicity the medium response is neglected in these calculations. The energy loss from purely elastic interactions is compared with the case where radiative processes are consistently included based on the matrix element by Gunion and Bertsch. From this comparison, gluon multiplication processes gg{yields}ggg are found to be the dominant source of energy loss within the approach employed here. The consequences for the quenching of gluons with high transverse momentum in fully dynamic simulations of Au+Au collisions at the BNL Relativistic Heavy Ion Collider (RHIC) energy of {radical}(s)=200A GeV are discussed in the second major part of this work. The results for central collisions as discussed in a previous publication are revisited, and first results on the nuclear modification factor R{sub AA} for noncentral Au+Au collisions are presented. They show a decreased quenching compared to central collisions while retaining the same shape. The investigation of the elliptic flow v{sub 2} is extended up to nonthermal transverse momenta of 10 GeV, exhibiting a maximum v{sub 2} at roughly 4 to 5 GeV and a subsequent decrease. Finally the sensitivity of the aforementioned results on the specific implementation of the effective modeling of the Landau-Pomeranchuk-Migdal (LPM) effect via a formation-time-based cutoff is explored.

  20. Pig Organ Energy Loss Comparison Experiments Using BBs.

    PubMed

    Maiden, Nicholas R; Musgrave, Ian; Fisk, Wesley; Byard, Roger W

    2016-05-01

    Torso models for ballistics research require that the mechanical properties of simulant materials must match the heterogeneous nature of tissues/organs within the human thorax/abdomen. A series of energy loss experiments were conducted on fresh porcine organs/tissues at room temperature and 37°C, using steel 4.5 mm BBs fired from a Daisy(®) brand air rifle. They were compared to FBI and NATO specification ordnance gelatin and a candidate surrogate material called Simulant "A". Two CED M2 chronographs measured BB velocity. The resulting energy loss was established using KE = 1/2 mv² before and after target perforation. The combined results at room temperature and 37°C were as follows: FBI specification gelatin was similar (p > 0.05) to heart and lung, spleen was similar to NATO specification gelatin, Simulant "A" was similar to hindquarter muscle, and hindquarter muscle, kidney, and spleen were similar to each other regarding energy retardation. These results can be used as a basis for the development of simulant materials to create an anatomically correct heterogeneous model. PMID:27122406

  1. Very Low Energy Supernovae from Neutrino Mass Loss

    NASA Astrophysics Data System (ADS)

    Lovegrove, Elizabeth; Woosley, S. E.

    2013-06-01

    It now seems likely that some percentage of more massive supernova progenitors do not explode by any of the currently discussed explosion mechanisms. This has led to speculation concerning the observable transients that might be produced if such a supernova fails. Even if a prompt outgoing shock fails to form in a collapsing presupernova star, one must still consider the hydrodynamic response of the star to the abrupt loss of mass via neutrinos as the core forms a protoneutron star. Following a suggestion by Nadezhin, we calculate the hydrodynamical responses of typical supernova progenitor stars to the rapid loss of approximately 0.2-0.5 M ⊙ of gravitational mass from their centers. In a red supergiant star, a very weak supernova with total kinetic energy ~1047 erg results. The binding energy of a large fraction of the hydrogen envelope before the explosion is of the same order and, depending upon assumptions regarding the maximum mass of a neutron star, most of it is ejected. Ejection speeds are ~100 km s-1 and luminosities ~1039 erg s-1 are maintained for about a year. A significant part of the energy comes from the recombination of hydrogen. The color of the explosion is extremely red and the events bear some similarity to "luminous red novae," but have much lower speeds.

  2. Method for reducing energy losses in laser crystals

    DOEpatents

    Atherton, L.J.; DeYoreo, J.J.; Roberts, D.H.

    1992-03-24

    A process for reducing energy losses in crystals is disclosed which comprises: a. heating a crystal to a temperature sufficiently high as to cause dissolution of microscopic inclusions into the crystal, thereby converting said inclusions into point-defects, and b. maintaining said crystal at a given temperature for a period of time sufficient to cause said point-defects to diffuse out of said crystal. Also disclosed are crystals treated by the process, and lasers utilizing the crystals as a source of light. 12 figs.

  3. Method for reducing energy losses in laser crystals

    DOEpatents

    Atherton, L. Jeffrey; DeYoreo, James J.; Roberts, David H.

    1992-01-01

    A process for reducing energy losses in crystals is disclosed which comprises: a. heating a crystal to a temperature sufficiently high as to cause dissolution of microscopic inclusions into the crystal, thereby converting said inclusions into point-defects, and b. maintaining said crystal at a given temperature for a period of time sufficient to cause said point-defects to diffuse out of said crystal. Also disclosed are crystals treated by the process, and lasers utilizing the crystals as a source of light.

  4. On the energy losses of fast charged particles

    NASA Astrophysics Data System (ADS)

    Matveev, V. I.; Makarov, D. N.; Gusarevich, E. S.

    2010-09-01

    The energy losses of fast charged particles colliding with atoms have been considered in the eikonal approximation. It has been shown that the nonperturbative contribution to the effective stopping from the region of the intermediate impact parameters (comparable with the characteristic sizes of the electron shells of the target) not only can be significant as compared to shell corrections to the Bethe-Bloch formula (usually considered in the first order of perturbation theory), but also can provide significant (up to 50%) corrections to this formula.

  5. Multiple scattering calculations of relativistic electron energy loss spectra

    NASA Astrophysics Data System (ADS)

    Jorissen, K.; Rehr, J. J.; Verbeeck, J.

    2010-04-01

    A generalization of the real-space Green’s-function approach is presented for ab initio calculations of relativistic electron energy loss spectra (EELS) which are particularly important in anisotropic materials. The approach incorporates relativistic effects in terms of the transition tensor within the dipole-selection rule. In particular, the method accounts for relativistic corrections to the magic angle in orientation resolved EELS experiments. The approach is validated by a study of the graphite CK edge, for which we present an accurate magic angle measurement consistent with the predicted value.

  6. Reconstructing Folding Energy Landscapes by Single-Molecule Force Spectroscopy

    PubMed Central

    Woodside, Michael T.; Block, Steven M.

    2015-01-01

    Folding may be described conceptually in terms of trajectories over a landscape of free energies corresponding to different molecular configurations. In practice, energy landscapes can be difficult to measure. Single-molecule force spectroscopy (SMFS), whereby structural changes are monitored in molecules subjected to controlled forces, has emerged as a powerful tool for probing energy landscapes. We summarize methods for reconstructing landscapes from force spectroscopy measurements under both equilibrium and nonequilibrium conditions. Other complementary, but technically less demanding, methods provide a model-dependent characterization of key features of the landscape. Once reconstructed, energy landscapes can be used to study critical folding parameters, such as the characteristic transition times required for structural changes and the effective diffusion coefficient setting the timescale for motions over the landscape. We also discuss issues that complicate measurement and interpretation, including the possibility of multiple states or pathways and the effects of projecting multiple dimensions onto a single coordinate. PMID:24895850

  7. Synthesis of Electron Energy Loss Spectra for the Quantification of Detection Limits

    NASA Astrophysics Data System (ADS)

    Menon, Nanda K.; Krivanek, Ondrej L.

    2002-06-01

    We describe a method for predicting detection limits of minority elements in electron energy loss spectroscopy (EELS), and its implementation as a software package that gives quantitative predictions for user-specified materials and experimental conditions. The method is based on modeling entire energy loss spectra, including shot noise as well as instrumental noise, and taking into account all the relevant experimental parameters. We describe the steps involved in modeling the entire spectrum, from the zero loss up to inner shell edges, and pay particular attention to the contributions to the pre-edge background. The predicted spectra are used to evaluate the signal-to-noise ratios (SNRs) for inner shell edges from user-specified minority elements. The software also predicts the minimum detectable mass (MDM) and minimum mass fraction (MMF). It can be used to ascertain whether an element present at a particular concentration should be detectable for given experimental conditions, and also to quickly and quantitatively explore ways of optimizing the experimental conditions for a particular EELS analytical task. We demonstrate the usefulness of the software by confirming the recent empirical observation of single atom detection using EELS of phosphorus in thin carbon films, and show the effect on the SNR of varying the acquisition parameters. The case of delta-doped semiconductors is also considered as an important example from materials science where low detection limits and high spatial resolution are essential, and the feasibility of such characterization using EELS is assessed.

  8. Real-Space Visualization of Energy Loss and Carrier Diffusion in a Semiconductor Nanowire Array Using 4D Electron Microscopy.

    PubMed

    Bose, Riya; Sun, Jingya; Khan, Jafar I; Shaheen, Basamat S; Adhikari, Aniruddha; Ng, Tien Khee; Burlakov, Victor M; Parida, Manas R; Priante, Davide; Goriely, Alain; Ooi, Boon S; Bakr, Osman M; Mohammed, Omar F

    2016-07-01

    A breakthrough in the development of 4D scanning ultrafast electron microscopy is described for real-time and space imaging of secondary electron energy loss and carrier diffusion on the surface of an array of nanowires as a model system, providing access to a territory that is beyond the reach of either static electron imaging or any time-resolved laser spectroscopy. PMID:27111855

  9. Coupling loss factor of linear vibration energy harvesting systems in a framework of statistical energy analysis

    NASA Astrophysics Data System (ADS)

    Wang, Xu

    2016-02-01

    This paper establishes coupling loss factor of linear vibration energy harvesting systems in a framework of statistical energy analysis under parameter variations and random excitations. The new contributions of this paper are to define the numerical ranges of the dimensionless force factor for the weak, moderate and strong coupling and to study the connections of dimensionless force factor, coupling loss factor, coupling quotient, critical coupling strength, electro-mechanical coupling factor, damping loss factor and modal densities in linear vibration energy harvesting systems. The motivation of this paper is to enable statistical energy analysis of linear vibration energy harvesting systems for reliable performance predictions and design optimisation under parameter variations of materials and manufacturing processes and random ambient environmental excitations.

  10. High-energy neutron spectroscopy with thick silicon detectors.

    PubMed

    Kinnison, James D; Maurer, Richard H; Roth, David R; Haight, Robert C

    2003-02-01

    The high-energy neutron component of the space radiation environment in thick structures such as the International Space Station contributes to the total radiation dose received by an astronaut. Detector design constraints such as size and mass have limited the energy range of neutron spectrum measurements in orbit to about 12 MeV in Space Shuttle studies. We present a new method for high-energy neutron spectroscopy using small silicon detectors that can extend these measurements to more than 500 MeV. The methodology is based on measurement of the detector response function for high-energy neutrons and inversion of this response function with measured deposition data to deduce neutron energy spectra. We also present the results of an initial shielding study performed with the thick silicon detector system for high-energy neutrons incident on polyethylene. PMID:12537520

  11. High-energy neutron spectroscopy with thick silicon detectors

    NASA Technical Reports Server (NTRS)

    Kinnison, James D.; Maurer, Richard H.; Roth, David R.; Haight, Robert C.

    2003-01-01

    The high-energy neutron component of the space radiation environment in thick structures such as the International Space Station contributes to the total radiation dose received by an astronaut. Detector design constraints such as size and mass have limited the energy range of neutron spectrum measurements in orbit to about 12 MeV in Space Shuttle studies. We present a new method for high-energy neutron spectroscopy using small silicon detectors that can extend these measurements to more than 500 MeV. The methodology is based on measurement of the detector response function for high-energy neutrons and inversion of this response function with measured deposition data to deduce neutron energy spectra. We also present the results of an initial shielding study performed with the thick silicon detector system for high-energy neutrons incident on polyethylene.

  12. Technology Roadmap. Energy Loss Reduction and Recovery in Industrial Energy Systems

    SciTech Connect

    none,

    2004-11-01

    To help guide R&D decision-making and gain industry insights on the top opportunities for improved energy systems, ITP sponsored the Energy Loss Reduction and Recoveryin Energy Systems Roadmapping Workshopin April 2004 in Baltimore, Maryland. This Technology Roadmapis based largely on the results of the workshop and additional industrial energy studies supported by ITP and EERE. It summarizes industry feedback on the top opportunities for R&D investments in energy systems, and the potential for national impacts on energy use and the environment.

  13. Accelerated quarks and energy loss in confinement theory

    NASA Astrophysics Data System (ADS)

    Ghoroku, Kazuo; Kubo, Kouki

    2016-06-01

    We study the energy loss rate (ELR) of the accelerated quark in terms of the holographic models for the two different motions, linear acceleration and uniform rotation. They are examined by two different nonconformal models with confinement. We found in both models that the value of ELR is bounded from below by the string tension of the linear confinement potential between quark and antiquark. The lower bounds of ELR are independent of the types of the motion of the quark. They are determined by the string tension at the worldsheet horizon of the model. These results are obtained when the model has the diagonal background metric. Then we find the common perspective for the lower bounds of ELRs of the two different motions.

  14. Effect of the electron energy distribution on total energy loss with argon in inductively coupled plasmas

    SciTech Connect

    Kim, June Young; Kim, Young-Cheol; Kim, Yu-Sin; Chung, Chin-Wook

    2015-01-15

    The total energy lost per electron-ion pair lost ε{sub T} is investigated with the electron energy distribution function (EEDF). The EEDFs are measured at various argon powers in RF inductively coupled plasma, and the EEDFs show a depleted distribution (a discontinuity occurring at the minimum argon excitation threshold energy level) with the bulk temperature and the tail temperature. The total energy loss per electron-ion pair lost ε{sub T} is calculated from a power balance model with the Maxwellian EEDFs and the depleted EEDFs and then compared with the measured ε{sub T} from the floating probe. It is concluded that the small population of the depleted high energy electrons dramatically increases the collisional energy loss, and the calculated ε{sub T} from the depleted EEDFs has a value that is similar to the measured ε{sub T}.

  15. Effect of the electron energy distribution on total energy loss with argon in inductively coupled plasmas

    NASA Astrophysics Data System (ADS)

    Kim, June Young; Kim, Young-Cheol; Kim, Yu-Sin; Chung, Chin-Wook

    2015-01-01

    The total energy lost per electron-ion pair lost ɛT is investigated with the electron energy distribution function (EEDF). The EEDFs are measured at various argon powers in RF inductively coupled plasma, and the EEDFs show a depleted distribution (a discontinuity occurring at the minimum argon excitation threshold energy level) with the bulk temperature and the tail temperature. The total energy loss per electron-ion pair lost ɛT is calculated from a power balance model with the Maxwellian EEDFs and the depleted EEDFs and then compared with the measured ɛT from the floating probe. It is concluded that the small population of the depleted high energy electrons dramatically increases the collisional energy loss, and the calculated ɛT from the depleted EEDFs has a value that is similar to the measured ɛT.

  16. Kramers-Kronig analysis of reflection electron-energy-loss spectra measured with a cylindrical mirror analyzer

    NASA Astrophysics Data System (ADS)

    Ohno, Youichi

    1989-04-01

    We have discussed a valence-electron energy-loss spectrum measured in reflection geometry using a cylindrical mirror analyzer (CMA) and derived the angular distribution of inelastic scattering, the momentum transfer, and the differential cross section per unit energy. If a critical inelastic-scattering angle is smaller than the angular aperture of the analyzer, the differential cross section no longer depends on momentum transfer. The reflection electron-energy-loss spectroscopy (REELS) spectra of MoS2 and graphite have been measured and the Kramers-Kronig analysis has been applied. The results are compared with those of the composite energy-loss function calculated from the energy-loss functions perpendicular and parallel to the c axis. It has been shown that the Kramers-Kronig analysis is still valid for the REELS spectra at higher incident energies than 500 eV and that the derived optical constants consist approximately of 80% of the perpendicular component and 20% of the parallel component.

  17. Energy loss mechanics in the erosion of cemented tungsten carbide

    SciTech Connect

    Freinkel, D.M. ); Luyckx, S.B. )

    1989-05-01

    The erosion of tungsten carbide has been studied by several researchers under various conditions: the cobalt content of the cemented carbide has been varied from 4.5 to 11.3 wt % Co, the size of the WC grains varied from 0.9 to 5.1 {mu}m, the size of the erodant particles varied from 30 to 630 {mu}m, the velocity of the particles varied from 30 to 507 m/s, and particle incidence angle varied from 15{degrees} to 90{degrees}. While it is generally agreed that with increasing cobalt content and increasing particle velocity the erosion rate of WC-Co increases, there is disagreement on the effect of grain size and angle of incidence. More work was clearly required to explain this disagreement, thus the present investigation was undertaken. The present work differs from previous experimental work in that the erodant particles are 4 mm average diameter and that the present investigation does not neglect the role of plastic deformation in the erosion process and the energy lost in damage to the erodant particles. These two additional energy loss mechanisms have been found to contribute significantly to the interpretation of the present results and of the results previously reported in the literature.

  18. Charm quark energy loss in proton-proton collisions at LHC energies

    NASA Astrophysics Data System (ADS)

    Vogel, Sascha; Gossiaux, Pol Bernard; Werner, Klaus; Aichelin, Jörg

    2013-03-01

    Heavy quarks, i.e. charm and bottom quarks are one of the crucial probes in the high energy nuclear collision program at current day accelerators. It has been shown at the Relativistic Heavy Ion Collider (RHIC) that heavy quarks show a remarkable medium suppression despite their high mass. In these proceedings we report on a study of heavy quark energy loss in high multiplicity proton-proton collisions at energies accessible to the Large Hadron Collider (LHC). Recent experimental results from the LHC collaborations have shown that the notion of creating an interacting system is not completely off limits. The higher energies in LHC proton-proton collisions lead to multiplicities comparable to Cu+Cu collisions at RHIC. Within this environment high-momentum heavy quarks experience a non-negligible energy loss.

  19. Electron-energy loss study of nonlocal effects in connected plasmonic nanoprisms.

    PubMed

    Wiener, Aeneas; Duan, Huigao; Bosman, Michel; Horsfield, Andrew P; Pendry, John B; Yang, Joel K W; Maier, Stefan A; Fernández-Domínguez, Antonio I

    2013-07-23

    We investigate the emergence of nonlocal effects in plasmonic nanostructures through electron-energy loss spectroscopy. To theoretically describe the spatial dispersion in the metal permittivity, we develop a full three-dimensional nonlocal hydrodynamic solution of Maxwell's equations in frequency domain that implements the electron beam as a line current source. We use our numerical approach to perform an exhaustive analysis of the impact of nonlocality in the plasmonic response of single triangular prisms and connected bowtie dimers. Our results demonstrate the complexity of the interplay between nonlocal and geometric effects taking place in these structures. We show the different sensitivities to both effects of the various plasmonic modes supported by these systems. Finally, we present an experimental electron-energy loss study on gold nanoprisms connected by bridges as narrow as 1.6 nm. The comparison with our theoretical predictions enables us to reveal in a phenomenological fashion the enhancement of absorption damping that occurs in these atomistic junctions due to quantum confinement and grain boundary electron scattering. PMID:23782059

  20. Elemental electron energy loss mapping of a precipitate in a multi-component aluminium alloy.

    PubMed

    Mørtsell, Eva A; Wenner, Sigurd; Longo, Paolo; Andersen, Sigmund J; Marioara, Calin D; Holmestad, Randi

    2016-07-01

    The elemental distribution of a precipitate cross section, situated in a lean Al-Mg-Si-Cu-Ag-Ge alloy, has been investigated in detail by electron energy loss spectroscopy (EELS) and aberration corrected high angle annular dark field scanning transmission electron microscopy (HAADF-STEM). A correlative analysis of the EELS data is connected to the results and discussed in detail. The energy loss maps for all relevant elements were recorded simultaneously. The good spatial resolution allows elemental distribution to be evaluated, such as by correlation functions, in addition to being compared with the HAADF image. The fcc-Al lattice and the hexagonal Si-network within the precipitates were resolved by EELS. The combination of EELS and HAADF-STEM demonstrated that some atomic columns consist of mixed elements, a result that would be very uncertain based on one of the techniques alone. EELS elemental mapping combined with a correlative analysis have great potential for identification and quantification of small amounts of elements at the atomic scale. PMID:27124585

  1. Spectroscopy of Light Nuclei with Low Energy Nuclear Reactions

    NASA Astrophysics Data System (ADS)

    Lombardo, I.; Dell'Aquila, D.; Vigilante, M.

    2016-07-01

    We discuss new results concerning the investigation of the 19F(p,α 0)16O and 10B(p,α 0)7Be reactions at low energies. Both reactions are important for the nuclear spectroscopy of the formed compound nucleus, i.e. 20Ne and 11C respectively, and play a role in nuclear astrophysics. For the 10B(p,α 0)7Be case, a comprehensive analysis of our reaction data and other scattering data points out the possible presence of an unreported state in 11C at Ex ≈ 9.36 MeV. For the 19F(p,α 0)16O case, the study of the low energy angular distributions testifies the role played by low energy resonances in the S-factor, leading to an enhanced reaction rate at stellar energies.

  2. Theoretical Basis and Application for Measuring Pork Loin Drip Loss Using Microwave Spectroscopy

    PubMed Central

    Mason, Alex; Abdullah, Badr; Muradov, Magomed; Korostynska, Olga; Al-Shamma’a, Ahmed; Bjarnadottir, Stefania Gudrun; Lunde, Kathrine; Alvseike, Ole

    2016-01-01

    During cutting and processing of meat, the loss of water is critical in determining both product quality and value. From the point of slaughter until packaging, water is lost due to the hanging, movement, handling, and cutting of the carcass, with every 1% of lost water having the potential to cost a large meat processing plant somewhere in the region of €50,000 per day. Currently the options for monitoring the loss of water from meat, or determining its drip loss, are limited to destructive tests which take 24–72 h to complete. This paper presents results from work which has led to the development of a novel microwave cavity sensor capable of providing an indication of drip loss within 6 min, while demonstrating good correlation with the well-known EZ-Driploss method (R2 = 0.896). PMID:26848661

  3. Theoretical Basis and Application for Measuring Pork Loin Drip Loss Using Microwave Spectroscopy.

    PubMed

    Mason, Alex; Abdullah, Badr; Muradov, Magomed; Korostynska, Olga; Al-Shamma'a, Ahmed; Bjarnadottir, Stefania Gudrun; Lunde, Kathrine; Alvseike, Ole

    2016-01-01

    During cutting and processing of meat, the loss of water is critical in determining both product quality and value. From the point of slaughter until packaging, water is lost due to the hanging, movement, handling, and cutting of the carcass, with every 1% of lost water having the potential to cost a large meat processing plant somewhere in the region of €50,000 per day. Currently the options for monitoring the loss of water from meat, or determining its drip loss, are limited to destructive tests which take 24-72 h to complete. This paper presents results from work which has led to the development of a novel microwave cavity sensor capable of providing an indication of drip loss within 6 min, while demonstrating good correlation with the well-known EZ-Driploss method (R² = 0.896). PMID:26848661

  4. Quantitative evaluation of the lactate signal loss and its spatial dependence in press localized (1)H NMR spectroscopy.

    PubMed

    Jung, W I; Bunse, M; Lutz, O

    2001-10-01

    Localized (1)H NMR spectroscopy using the 90 degrees -t(1)-180 degrees -t(1)+t(2)-180 degrees -t(2)-Acq. PRESS sequence can lead to a signal loss for the lactate doublet compared with signals from uncoupled nuclei which is dependent on the choice of t(1) and t(2). The most striking signal loss of up to 78% of the total signal occurs with the symmetrical PRESS sequence (t(1)=t(2)) at an echo time of 2/J (approximately 290 ms). Calculations have shown that this signal loss is related to the pulse angle distributions produced by the two refocusing pulses which leads to the creation of single quantum polarization transfer (PT) as well as to not directly observable states (NDOS) of the lactate AX(3) spin system: zero- and multiple-quantum coherences, and longitudinal spin orders. In addition, the chemical shift dependent voxel displacement (VOD) leads to further signal loss. By calculating the density operator for various of the echo times TE=n/J, n=1, 2, 3,..., we calculated quantitatively the contributions of these effects to the signal loss as well as their spatial distribution. A maximum signal loss of 75% can be expected from theory for the symmetrical PRESS sequence and TE=2/J for Hamming filtered sinc pulses, whereby 47% are due to the creation of NDOS and up to 28% arise from PT. Taking also the VOD effect into account (2 mT/m slice selection gradients, 20-mm slices) leads to 54% signal loss from NDOS and up to 24% from PT, leading to a maximum signal loss of 78%. Using RE-BURP pulses with their more rectangular pulse angle distributions reduces the maximum signal loss to 44%. Experiments at 1.5 T using a lactate solution demonstrated a maximum lactate signal loss for sinc pulses of 82% (52% NDOS, 30% PT) at TE=290 ms using the symmetrical PRESS sequence. The great signal loss and its spatial distribution is of importance for investigations using a symmetrical PRESS sequence at TE=2/J. PMID:11567573

  5. Quantitative Evaluation of the Lactate Signal Loss and Its Spatial Dependence in PRESS Localized 1H NMR Spectroscopy

    NASA Astrophysics Data System (ADS)

    Jung, Wulf-Ingo; Bunse, Michael; Lutz, Otto

    2001-10-01

    Localized 1H NMR spectroscopy using the 90°-t1-180°-t1+t2-180°-t2-Acq. PRESS sequence can lead to a signal loss for the lactate doublet compared with signals from uncoupled nuclei which is dependent on the choice of t1 and t2. The most striking signal loss of up to 78% of the total signal occurs with the symmetrical PRESS sequence (t1=t2) at an echo time of 2/J (≃290 ms). Calculations have shown that this signal loss is related to the pulse angle distributions produced by the two refocusing pulses which leads to the creation of single quantum polarization transfer (PT) as well as to not directly observable states (NDOS) of the lactate AX3 spin system: zero- and multiple-quantum coherences, and longitudinal spin orders. In addition, the chemical shift dependent voxel displacement (VOD) leads to further signal loss. By calculating the density operator for various of the echo times TE=n/J, n=1, 2, 3, …, we calculated quantitatively the contributions of these effects to the signal loss as well as their spatial distribution. A maximum signal loss of 75% can be expected from theory for the symmetrical PRESS sequence and TE=2/J for Hamming filtered sinc pulses, whereby 47% are due to the creation of NDOS and up to 28% arise from PT. Taking also the VOD effect into account (2 mT/m slice selection gradients, 20-mm slices) leads to 54% signal loss from NDOS and up to 24% from PT, leading to a maximum signal loss of 78%. Using RE-BURP pulses with their more rectangular pulse angle distributions reduces the maximum signal loss to 44%. Experiments at 1.5 T using a lactate solution demonstrated a maximum lactate signal loss for sinc pulses of 82% (52% NDOS, 30% PT) at TE=290 ms using the symmetrical PRESS sequence. The great signal loss and its spatial distribution is of importance for investigations using a symmetrical PRESS sequence at TE=2/J.

  6. ENERGY LOSS AT THREE-WAY CIRCULAR MANHOLE UNDER SURCHARGE FLOW

    NASA Astrophysics Data System (ADS)

    Arao, Shinji; Moriyama, Katsumi; Asada, Jyunsaku; Hirose, Nozomu; Kusuda, Tetsuya

    The energy loss at manholes in a storm sewer network is often compared with the friction loss in pipes under a surcharge flow. It is important to estimate the energy loss at manholes exactly in the design of a storm sewer network and in a flood-analysis. Some researchers have already investigated the energy loss at three-way manholes. However, the relationship between the energy loss and the water depth in manholes has not been enough studied yet. In this study, the effect of the water depth and the ratio of the flow rates in the lateral and in the downstream pipes on the energy loss at a three-way circular manhole was investigated. This study also proposed a modified formula for energy loss coefficients described in Urban Drainage Design Manual, USA (2001) for the three-way manhole.

  7. Energy loss of protons and deuterons at low energies in Pd polycrystalline thin films

    NASA Astrophysics Data System (ADS)

    Celedón, C.; Sánchez, E. A.; Moreno, M. S.; Arista, N. R.; Uribe, J. D.; Mery, M.; Valdés, J. E.; Vargas, P.

    2013-07-01

    We have investigated experimentally and by computer simulations the energy-loss distributions of low-energy (E<10 keV) protons and deuterons transmitted through polycrystalline palladium thin films. In contrast to previous experiments on various transition metals we find that the stopping power of Pd is proportional to the ion velocity. Data of protons and deuterons are coincident within the experimental uncertainties, showing the absence of an isotopic effect on the stopping power of Pd in this energy range. The experimental results were analyzed and compared with Monte Carlo computer simulations and previous theoretical models. The difference in the velocity dependence of the energy loss of hydrogen ions in Pd with respect to other transition metals (Cu, Ag, and Au) is explained by a theoretical analysis based on the properties of the d-electron bands of those elements.

  8. Daily energy expenditure and physical activity measured in Parkinson's disease patients with and without weight loss

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Patients with Parkinson's disease (PD) commonly exhibit weight loss, which investigators attribute to various factors, including elevated resting energy expenditure. We tested the hypothesis that daily energy expenditure (DEE) and its components, resting energy expenditure (REF) and physical activit...

  9. Daily energy expenditure, physical activity, and weight loss in Parkinson's disease patients

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Patients with Parkinson's disease (PD) commonly exhibit weight loss (WL) which investigators attribute to various factors, including elevated energy expenditure. We tested the hypothesis that daily energy expenditure (DEE) and its components, resting energy expenditure (REE) and physical activity (P...

  10. Energy loss of heavy ions at high velocity

    NASA Astrophysics Data System (ADS)

    Andersen, J. U.; Ball, G. C.; Davies, J. A.; Davies, W. G.; Forster, J. S.; Geiger, J. S.; Geissel, H.; Ryabov, V. A.

    1994-05-01

    The slowing down of heavy ions by electronic stopping at high velocity is discussed. The ions are nearly fully stripped and have a well defined charge with relatively small fluctuations. Owing to the large charge of the ions, the classical Bohr formula applies instead of the Bethe formula, which is based on a quantum perturbation calculation. It is essential to include the Barkas effect in the description since it becomes quite large for heavy ions, especially in high-Z materials. In Lindhard's treatment [Nucl. Instr. and Meth. 132 (1976) l], the Barkas correction is viewed as an effect of dynamic screening of the ion potential in the initial phase of a collision with an electron, which reduces the relative velocity and therefore enhances the cross section. With inclusion of this enhancement factor for all impact parameters, as evaluated by Jackson and McCarthy for distant collisions [Phys. Rev. B 6 (1972) 4131], the description reproduces within a few percent measurements for 15 MeV/u Br on Si, Ni, and Au and for 10 MeV/u Kr on Al, Ni, and Au. The procedure is shown also to apply at lower velocities near the stopping maximum, albeit with less accuracy. The straggling in energy loss has been analyzed for a measurement on Si and it is well described by a combination of about equal contributions from fluctuations in the number of violent collisions with single electrons (Bohr straggling) and from fluctuations in ion charge state.

  11. Self-Directed Weight Loss Strategies: Energy Expenditure Due to Physical Activity Is Not Increased to Achieve Intended Weight Loss

    PubMed Central

    Elbelt, Ulf; Schuetz, Tatjana; Knoll, Nina; Burkert, Silke

    2015-01-01

    Reduced physical activity and almost unlimited availability of food are major contributors to the development of obesity. With the decline of strenuous work, energy expenditure due to spontaneous physical activity has attracted increasing attention. Our aim was to assess changes in energy expenditure, physical activity patterns and nutritional habits in obese subjects aiming at self-directed weight loss. Methods: Energy expenditure and physical activity patterns were measured with a portable armband device. Nutritional habits were assessed with a food frequency questionnaire. Results: Data on weight development, energy expenditure, physical activity patterns and nutritional habits were obtained for 105 patients over a six-month period from an initial cohort of 160 outpatients aiming at weight loss. Mean weight loss was −1.5 ± 7.0 kg (p = 0.028). Patients with weight maintenance (n = 75), with substantial weight loss (>5% body weight, n = 20) and with substantial weight gain (>5% body weight, n = 10) did not differ in regard to changes of body weight adjusted energy expenditure components (total energy expenditure: −0.2 kcal/kg/day; non-exercise activity thermogenesis: −0.3 kcal/kg/day; exercise-related activity thermogenesis (EAT): −0.2 kcal/kg/day) or patterns of physical activity (duration of EAT: −2 min/day; steps/day: −156; metabolic equivalent unchanged) measured objectively with a portable armband device. Self-reported consumption frequency of unfavorable food decreased significantly (p = 0.019) over the six-month period. Conclusions: An increase in energy expenditure or changes of physical activity patterns (objectively assessed with a portable armband device) are not employed by obese subjects to achieve self-directed weight loss. However, modified nutritional habits could be detected with the use of a food frequency questionnaire. PMID:26193310

  12. A low and hyperthemal energy UHV ion beamline for surface scattering spectroscopies

    NASA Astrophysics Data System (ADS)

    Ray, M. P.; Moody, S. A.; Sosolik, C. E.

    2006-03-01

    We are using a differentially pumped beamline to provide well- collimated, monoenergetic beams of noble gas and alkali-metal ions that range in energy from <10eV to 10keV. These ion beams are scattered from a surface (e.g. Cu(001)) to study charge transfer effects, energy loss, and the excitation of surface phonons and excitons. The ion beam is focused into a UHV scattering chamber that possesses capabilities for studying and characterizing samples using LEED, Auger spectroscopy, and a Kelvin probe for work function measurements. Recent additions to this setup include replacing diffusion pumps with turbo pumps as well as the addition of a fast entry load-lock sample exchange system. Our current research is focused on developing a source to produce an ion beam of C60 as well as studying charge transfer and energy loss effects at the low and hyperthermal energy range. Also, we are investigating chemicurrents associated with Schottky diodes in this energy regime.

  13. Proton MR spectroscopy in herpes simplex encephalitis: Assessment of neuronal loss

    SciTech Connect

    Menon, D.K.; Sargentoni, J.; Peden, C.J.; Bell, J.D.; Cox, I.J.; Coutts, G.A.; Baudouin, C.; Newman, C.G. )

    1990-05-01

    We present here the case of an 11-year-old boy with herpes simplex encephalitis diagnosed on the basis of clinical features, serology, and response to acyclovir, who relapsed after 3 weeks of therapy. In vivo proton magnetic resonance spectroscopy (1H MRS) of the brain, at 8 and 16 weeks after the onset of symptoms, showed abnormalities, most prominently a reduction in the N-acetylaspartate/choline ratio. The role of 1H MRS in assessing disease activity is discussed.

  14. Oxygen-induced changes in electron-energy-loss spectra for Al, Be and Ni. [Al; Be; Ni

    SciTech Connect

    Madden, H.H.; Landers, R.; Kleiman, G.G. , 13081-970 Campinas, Sao Paulo, Brasil); Zehner, D.M. )

    1999-09-01

    Electron-energy-loss spectroscopy (EELS) data are presented to illustrate line shape changes that occur as a result of oxygen interaction with metal surfaces. The metals were aluminum, beryllium and nickel. Core-level EELS data were taken for excitations from Al(2p), Be(1s), Ni(3p/3s) and O(1s) levels to the conduction band (CB) density of states (DOS) of the materials. The primary beam energies for the spectra were 300, 450, 300, and 1135 eV, respectively. The data are presented in both the (as measured) first-derivative and the integral forms. The integral spectra were corrected for coherent background losses and analyzed for CB DOS information. These spectra were found to be in qualitative agreement with published experimental and theoretical studies of these materials. One peak in the spectra for Al oxide is analyzed for its correlation with excitonic screening of the Al(2p) core hole. Similar evidence for exciton formation is found in the Ni(3p) spectra for Ni oxide. Data are also presented showing oxygen-induced changes in the lower-loss-energy EELS curves that, in the pure metal, are dominated by plasmon-loss and interband-transition signals. Single-scattering loss profiles in the integral form of the data were calculated using a procedure of Tougaard and Chorkendorff [S. Tougaard and I. Chorkendorff, Phys. Rev. B. [bold 35], 6570 (1987)]. For all three oxides these profiles are dominated by a feature with a loss energy of around 20[endash]25 eV. Although this feature has been ascribed by other researchers as due to bulk plasmon losses in the oxide, an alternative explanation is that the feature is simply due to O(2s)-to-CB-level excitations. An even stronger feature is found at 7 eV loss energy for Ni oxide. Speculation is given as to its source. The line shapes in both the core-level and noncore-level spectra can also be used simply as [open quotes]fingerprints[close quotes] of the surface chemistry of the materials. Our data were taken using commercially

  15. Action Spectroscopy and Dissociation Energy of Ammonia Trimer

    NASA Astrophysics Data System (ADS)

    Heid, Cornelia G.; Case, Amanda S.; Western, Colin M.; Crim, F. Fleming

    2012-06-01

    We have investigated the energy dependence for the vibrational predissociation of ammonia trimer, (NH_3)_3 → (NH_3)_2 + NH_3, using infrared-action spectroscopy. The action spectra come from detecting specific rovibrational states of the monomer fragment via (2+1) resonance enhanced multiphoton excitation (REMPI) while scanning the IR excitation laser over the NH stretch transitions of the trimer as well as the dimer. The relative intensities of the dimer and trimer features in the action spectra depend on the amount of energy available for breaking the hydrogen bonds in the clusters. For example, the action spectra of ammonia fragments with large amounts of internal energy (v_2=3) show almost no trimer contribution since there is not enough energy available to break two bonds in the cyclic trimer. The action spectra for fragments with low internal energies (v_2=1), on the other hand, exhibit a substantial trimer component as more energy remains available to dissociate the cluster. Using the threshold at which the trimer feature becomes apparent in our spectra as an upper limit (Edissmax = hνvib-Eint(NH_3)), we determine the dissociation energy of ammonia trimer to be in the range between 1700-1800 cm-1. This range agrees well with theoretical predictions.

  16. Development of decay energy spectroscopy using low temperature detectors.

    PubMed

    Jang, Y S; Kim, G B; Kim, K J; Kim, M S; Lee, H J; Lee, J S; Lee, K B; Lee, M K; Lee, S J; Ri, H C; Yoon, W S; Yuryev, Y N; Kim, Y H

    2012-09-01

    We have developed a high-resolution detection technique for measuring the energy and activity of alpha decay events using low-temperature detectors. A small amount of source material containing alpha-emitting radionuclides was enclosed in a 4π metal absorber. The energy of the alpha particles as well as that of the recoiled nuclides, low-energy electrons, and low-energy x-rays and γ-rays was converted into thermal energy of the gold absorber. A metallic magnetic calorimeter serving as a fast and sensitive thermometer was thermally attached to the metal absorber. In the present report, experimental demonstrations of Q spectroscopy were made with a new meander-type magnetic calorimeter. The thermal connection between the temperature sensor and the absorber was established with annealed gold wires. Each alpha decay event in the absorber resulted in a temperature increase of the absorber and the temperature sensor. Using the spectrum measured for a drop of (226)Ra solution in a 4π gold absorber, all of the alpha emitters in the sample were identified with a demonstration of good detector linearity. The resolution of the (226)Ra spectrum showed a 3.3 keV FWHM at its Q value together with an expected gamma escape peak at the energy shifted by its γ-ray energy. PMID:22410296

  17. Nonlinear effects in the energy loss of a slow dipole in a free-electron gas

    SciTech Connect

    Alducin, M.; Juaristi, J.I.

    2002-11-01

    We analyze beyond linear-response theory the energy loss of a slow dipole moving inside a free-electron gas. The energy loss is obtained from a nonlinear treatment of the scattering of electrons at the dipole-induced potential. This potential and the total electronic density are calculated with density-functional theory. We focus on the interference effects, i.e., the difference between the energy loss of a dipole and that of the isolated charges forming it. Comparison of our results to those obtained in linear-response theory shows that a nonlinear treatment of the screening is required to accurately describe the energy loss of slow dipoles.

  18. Gravity Resonance Spectroscopy Constrains Dark Energy and Dark Matter Scenarios

    NASA Astrophysics Data System (ADS)

    Jenke, T.; Cronenberg, G.; Burgdörfer, J.; Chizhova, L. A.; Geltenbort, P.; Ivanov, A. N.; Lauer, T.; Lins, T.; Rotter, S.; Saul, H.; Schmidt, U.; Abele, H.

    2014-04-01

    We report on precision resonance spectroscopy measurements of quantum states of ultracold neutrons confined above the surface of a horizontal mirror by the gravity potential of Earth. Resonant transitions between several of the lowest quantum states are observed for the first time. These measurements demonstrate that Newton's inverse square law of gravity is understood at micron distances on an energy scale of 10-14 eV. At this level of precision, we are able to provide constraints on any possible gravitylike interaction. In particular, a dark energy chameleon field is excluded for values of the coupling constant β >5.8×108 at 95% confidence level (C.L.), and an attractive (repulsive) dark matter axionlike spin-mass coupling is excluded for the coupling strength gsgp>3.7×10-16 (5.3×10-16) at a Yukawa length of λ =20 μm (95% C.L.).

  19. Visible/Infrared Imaging Spectroscopy and Energy-Resolving Detectors

    NASA Astrophysics Data System (ADS)

    Eisenhauer, Frank; Raab, Walfried

    2015-08-01

    Imaging spectroscopy has seen rapid progress over the past 25 years, leading to breakthroughs in many fields of astronomy that would not have been otherwise possible. This review overviews the visible/infrared imaging spectroscopy techniques as well as energy-resolving detectors. We introduce the working principle of scanning Fabry-Perot and Fourier transform spectrometers and explain the most common integral field concepts based on mirror slicers, lenslet arrays, and fibers. The main advantage of integral field spectrographs is the simultaneous measurement of spatial and spectral information. Although Fabry-Perot and Fourier transform spectrometers can provide a larger field of view, it is ultimately the higher sensitivity of integral field units that make them the technique of choice. This is arguably the case for image slicers, which make the most efficient use of the available detector pixels and have equal or higher transmission than lenslet arrays and fiber integral field units, respectively. We also address the more specific issues of large étendue operation, focal ratio degradation, anamorphic magnification, and diffraction-limited operation. This review also covers the emerging technology of energy-resolving detectors, which promise very simple and efficient instrument designs. These energy-resolving detectors are based on superconducting thin film technology and exploit either the very small superconducting energy to count the number of quasi-particles excited in the absorption of the photon or the extremely steep phase transition between the normal- and superconducting phase to measure a temperature increase. We have put special emphasis on an overview of the underlying physical phenomena as well as on the recent technological progress and astronomical path finder experiments.

  20. Resolving Losses at the Negative Electrode in All-Vanadium Redox Flow Batteries Using Electrochemical Impedance Spectroscopy

    SciTech Connect

    Sun, Che Nan; Delnick, Frank M; Aaron, D; Mench, Matthew M; Zawodzinski, Thomas A

    2014-01-01

    We present an in situ electrochemical technique for the quantitative measurement and resolution of the ohmic, charge transfer and diffusion overvoltages at the negative electrode of an all-vanadium redox flow battery (VRFB) using electrochemical impedance spectroscopy (EIS). The mathematics describing the complex impedance of the V+2/V+3 redox reaction is derived and matches the experimental data. The voltage losses contributed by each process have been resolved and quantified at various flow rates and electrode thicknesses as a function of current density during anodic and cathodic polarization. The diffusion overvoltage was affected strongly by flow rate while the charge transfer and ohmic losses were invariant. On the other hand, adopting a thicker electrode significantly changed both the charge transfer and diffusion losses due to increased surface area. Furthermore, the Tafel plot obtained from the impedance resolved charge transfer overvoltage yielded the geometric exchange current density, anodic and cathodic Tafel slopes (135 5 and 121 5 mV/decade respectively) and corresponding transfer coefficients = 0.45 0.02 and = 0.50 0.02 in an operating cell.

  1. Modeling heavy ion ionization energy loss at low and intermediate energies

    SciTech Connect

    Rakhno, I.L.; /Fermilab

    2009-11-01

    The needs of contemporary accelerator and space projects led to significant efforts made to include description of heavy ion interactions with matter in general-purpose Monte Carlo codes. This paper deals with an updated model of heavy ion ionization energy loss developed previously for the MARS code. The model agrees well with experimental data for various projectiles and targets including super-heavy ions in low-Z media.

  2. Energy loss of a heavy particle near 3D charged rotating hairy black hole

    NASA Astrophysics Data System (ADS)

    Naji, Jalil

    2014-01-01

    In this paper we consider a charged rotating black hole in three dimensions with a scalar charge and discuss the energy loss of a heavy particle moving near the black-hole horizon. We also study quasi-normal modes and find the dispersion relations. We find that the effect of scalar charge and electric charge increases the energy loss.

  3. Effects of dietary composition of energy expenditure during weight-loss maintenance

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Reduced energy expenditure following weight loss is thought to contribute to weight gain. However, the effect of dietary composition on energy expenditure during weight-loss maintenance has not been studied. To examine the effects of 3 diets differing widely in macronutrient composition and glycemic...

  4. Evaluation of economic loss from energy-related environmental pollution: a case study of Beijing

    NASA Astrophysics Data System (ADS)

    Chen, Chen; Su, Meirong; Liu, Gengyuan; Yang, Zhifeng

    2013-09-01

    With the growth of energy consumption, energy-related environmental pollution has become increasingly serious, which in turn causes enormous economic loss because of public health damage, corrosion of materials, crop yield reduction, and other factors. Evaluating economic loss caused by energy-related environmental pollution can contribute to decision making in energy management. A framework for evaluating economic loss from environmental pollution produced during energy production, transportation, and consumption is proposed in this paper. Regarding SO2, PM10, and solid waste as the main pollutants, economic losses from health damage, materials corrosion, crop yield reduction, and solid waste pollution are estimated based on multiple concentration-response relationships and dose-response functions. The proposed framework and evaluation methods are applied to Beijing, China. It is evident that total economic loss attributable to energy-related environmental pollution fluctuated during 2000-2011 but had a general growth trend, with the highest value reaching 2.3 × 108 CNY (China Yuan) in 2006. Economic loss caused by health damage contributes most to the total loss among the four measured damage types. The total economic loss strongly correlates with the amount of energy consumption, especially for oil and electricity. Our evaluation framework and methods can be used widely to measure the potential impact of environmental pollution in the energy lifecycle.

  5. Mössbauer spectroscopy, magnetic characteristics, and reflection loss analysis of nickel-strontium substituted cobalt ferrite nanoparticles

    SciTech Connect

    Ghasemi, Ali; Paesano, Andrea; Cerqueira Machado, Carla Fabiana; Shirsath, Sagar E.; Liu, Xiaoxi; Morisako, Akimitsu

    2014-05-07

    In current research work, Co{sub 1-x}Ni{sub x/2}Sr{sub x/2}Fe{sub 2}O{sub 4} (x = 0–1 in a step of 0.2) ferrite nanoparticles were synthesized by a sol-gel method. According to the evolution in the subspectral areas obtained from Mössbauer spectroscopy, it was found that the relaxing iron belongs mostly to the site B, since the Mössbauer fraction of site A does not vary appreciably. With an increase in Ni-Sr substitution contents in cobalt ferrite, the coercivity and saturation of magnetization decrease. Variation of reflection loss versus frequency in microwave X-band demonstrates that the reflection peak shifts to lower frequency by adding substituted cations and the synthesized nanoparticles can be considered for application in electromagnetic wave absorber technology.

  6. Optical spectroscopy and energy-filtered transmission electron microscopy of surface plasmons in core-shell nanoparticles.

    SciTech Connect

    Eggeman, A. S.; Dobson, P. J.; Petford-Long, A. K.; Materials Science Division; Oxford Univ.

    2007-01-01

    Silica-silver core-shell nanoparticles were produced using colloidal chemistry methods. Surface plasmon resonances in the silver shells were investigated using optical absorption measurements in ultraviolet-to-visible (UV-vis) spectroscopy and the effect of shell thickness on the wavelength of the resonance was noted. Further studies of the resonances were performed using electron-energy-loss spectroscopy (EELS) and energy-filtered transmission electron microscope (EFTEM) imaging. The plasmon resonance was seen in an EELS spectrum at an energy corresponding to the wavelengths measured in an UV-vis spectrophotometer, and EFTEM images confirmed that the resonance was indeed localized at the surface of the silver shell. Further features were seen in the EELS spectrum and confirmed as bulk-plasmon features of silica and the carbon support film in the TEM specimen.

  7. The role of electronic energy loss in ion beam modification of materials

    DOE PAGESBeta

    Weber, William J.; Duffy, Dorothy M.; Thome, Lionel; Zhang, Yanwen

    2014-10-05

    The interaction of energetic ions with solids results in energy loss to both atomic nuclei and electrons in the solid. In this article, recent advances in understanding and modeling the additive and competitive effects of nuclear and electronic energy loss on the response of materials to ion irradiation are reviewed. Experimental methods and large-scale atomistic simulations are used to study the separate and combined effects of nuclear and electronic energy loss on ion beam modification of materials. The results demonstrate that nuclear and electronic energy loss can lead to additive effects on irradiation damage production in some materials; while inmore » other materials, the competitive effects of electronic energy loss leads to recovery of damage induced by elastic collision cascades. Lastly, these results have significant implications for ion beam modification of materials, non-thermal recovery of ion implantation damage, and the response of materials to extreme radiation environments.« less

  8. The role of electronic energy loss in ion beam modification of materials

    SciTech Connect

    Weber, William J.; Duffy, Dorothy M.; Thome, Lionel; Zhang, Yanwen

    2014-10-05

    The interaction of energetic ions with solids results in energy loss to both atomic nuclei and electrons in the solid. In this article, recent advances in understanding and modeling the additive and competitive effects of nuclear and electronic energy loss on the response of materials to ion irradiation are reviewed. Experimental methods and large-scale atomistic simulations are used to study the separate and combined effects of nuclear and electronic energy loss on ion beam modification of materials. The results demonstrate that nuclear and electronic energy loss can lead to additive effects on irradiation damage production in some materials; while in other materials, the competitive effects of electronic energy loss leads to recovery of damage induced by elastic collision cascades. Lastly, these results have significant implications for ion beam modification of materials, non-thermal recovery of ion implantation damage, and the response of materials to extreme radiation environments.

  9. Energy loss of heavy ions in solids at energies below 5 MeV/u

    NASA Astrophysics Data System (ADS)

    Sharma, Annu; Kumar, Shyam; Pathak, A. P.

    1999-06-01

    A comparative study of various energy loss formulations has been made by comparing the calculated stopping power values with the corresponding experimental values for projectiles 6⩽Z⩽92 in targets 4⩽Z⩽79 in the energy region ˜0.1-5.0 MeV/u. Some systematic and interesting trends have been observed in case of LSS theory. The limitations of TRIM and SRIM calculations have been demonstrated. Stopping power calculations using Hubert et al. formulation have been extended successfully beyond its recommended range of validity i.e. 2.5-500 MeV/u down to energies as low as 0.5 MeV/u for projectiles Z⩽29 in targets upto copper.

  10. Lifestyle modification to promote weight loss in the absence of energy restriction

    Technology Transfer Automated Retrieval System (TEKTRAN)

    With the obesity epidemic showing no signs of abating, there is ongoing interest in altering energy balance (i.e., decreasing energy intake and/or increasing energy expenditure) to promote weight, specifically fat, loss. However, short- and long-term outcomes of, and adherence to, decreasing energy ...

  11. Channeling energy loss and dechanneling of He along axial and planar directions of Si

    NASA Astrophysics Data System (ADS)

    Shafiei, S.; Lamehi-Rachti, M.

    2016-01-01

    In the present work, the energy loss and the dechanneling of He ions in the energy of 1.5 MeV and 2 MeV along the <1 0 0> and <1 1 0> axial directions as well as the {1 0 0} and {1 1 0} planar directions of Si were studied by the simulation of the channeling Rutherford backscattering spectra. The simulation was done based on the considerations that a fraction of the aligned beam enters the sample as a random component due to the ions scattering from the surface, and the dechanneling starts at the greater penetration depths, xDech. It was presumed that the dechanneling process follows a simple exponential law with a parameter λ which is proportional to the half-thickness. The Levenberg-Marquardt algorithm was used to set the best parameters of energy loss ratio, xDech and λ. The experimental results are well reproduced by this simulation. Differences between various axial and planar channels in the Si crystal and their influence on the energy loss ratio and dechanneling of He ions are described. Moreover, the energy dependence of energy loss ratio and dechanneling of He ions were investigated. It is shown that the dechanneling behavior of ions depends on the energy and energy loss of the ions along a channel. The channeled to random energy loss increases by decreasing ions energy.

  12. A coupled effect of nuclear and electronic energy loss on ion irradiation damage in lithium niobate

    DOE PAGESBeta

    Liu, Peng; Zhang, Yanwen; Xue, Haizhou; Jin, Ke; Crespillo, Miguel L.; Wang, Xuelin; Weber, William J.

    2016-01-09

    Understanding irradiation effects induced by elastic energy loss to atomic nuclei and inelastic energy loss to electrons in a crystal, as well as the coupled effect between them, is a scientific challenge. Damage evolution in LiNbO3 irradiated by 0.9 and 21 MeV Si ions at 300 K has been studied utilizing Rutherford backscattering spectrometry in channeling mode. During the low-energy ion irradiation process, damage accumulation produced due to elastic collisions is described utilizing a disorder accumulation model. Moreover, low electronic energy loss is shown to induce observable damage that increases with ion fluence. For the same electronic energy loss, themore » velocity of the incident ion could affect the energy and spatial distribution of excited electrons, and therefore effectively modify the diameter of the ion track. Furthermore, nonlinear additive phenomenon of irradiation damage induced by high electronic energy loss in pre-damaged LiNbO3 has been observed. The result indicates that pre-existing damage induced from nuclear energy loss interacts synergistically with inelastic electronic energy loss to promote the formation of amorphous tracks and lead to rapid phase transformation, much more efficient than what is observed in pristine crystal solely induced by electronic energy loss. As a result, this synergistic effect is attributed to the fundamental mechanism that the defects produced by the elastic collisions result in a decrease in thermal conductivity, increase in the electron-phonon coupling, and further lead to higher intensity in thermal spike from intense electronic energy deposition along high-energy ion trajectory.« less

  13. Energy losses and mean free paths of electrons in silicon dioxide

    SciTech Connect

    Ashley, J.C.; Anderson, V.E.

    1981-01-01

    Theoretical models and calculations are combined with experimental optical data to determine a model energy-loss function for SiO/sub 2/. Sumrule checks and comparisons with experimental information are made to insure overall consistency of the model. The model energy-loss function is employed to calculate electron inelastic mean free paths and stopping powers for electrons with energies less than or equal to 10 keV in SiO/sub 2/.

  14. Evolutionary developments in x ray and electron energy loss microanalysis instrumentation for the analytical electron microscope

    NASA Astrophysics Data System (ADS)

    Zaluzec, Nester J.

    Developments in instrumentation for both X ray Dispersive and Electron Energy Loss Spectroscopy (XEDS/EELS) over the last ten years have given the experimentalist a greatly enhanced set of analytical tools for characterization. Microanalysts have waited for nearly two decades now in the hope of getting a true analytical microscope and the development of 300 to 400 kV instruments should have allowed us to attain this goal. Unfortunately, this has not generally been the case. While there have been some major improvements in the techniques, there has also been some devolution in the modern AEM (Analytical Electron Microscope). In XEDS, the majority of today's instruments are still plagued by the hole count effect, which was first described in detail over fifteen years ago. The magnitude of this problem can still reach the 20 percent level for medium atomic number species in a conventional off-the-shelf intermediate voltage AEM. This is an absurd situation and the manufacturers should be severely criticized. Part of the blame, however, also rests on the AEM community for not having come up with a universally agreed upon standard test procedure. Fortunately, such a test procedure is in the early stages of refinement. The proposed test specimen consists of an evaporated Cr film approx. 500 to 1000A thick supported upon a 3mm diameter Molybdenum 200 micron aperture.

  15. Energy loss and straggling of MeV ions through biological samples

    SciTech Connect

    Ma Lei; Wang Yugang; Xue Jianming; Chen Qizhong; Zhang Weiming; Zhang Yanwen

    2007-10-15

    Energy loss and energy straggling of energetic ions through natural dehydrated biological samples were investigated using transmission technique. Biological samples (onion membrane, egg coat, and tomato coat) with different mass thickness were studied, together with Mylar for comparison. The energy loss and energy straggling of MeV H and He ions after penetrating the biological and Mylar samples were measured. The experimental results show that the average energy losses of MeV ions through the biological samples are consistent with SRIM predictions; however, large deviation in energy straggling is observed between the measured results and the SRIM predictions. Taking into account inhomogeneity in mass density and structure of the biological sample, an energy straggling formula is suggested, and the experimental energy straggling values are well predicted by the proposed formula.

  16. Energy loss and straggling of MeV ions through biological samples

    SciTech Connect

    Ma, Lie; Wang, Yugang; Xue, Jianming; Chen, Qizhong; Zhang, Weiming; Zhang, Yanwen

    2007-10-15

    Energy loss and energy straggling of energetic ions through natural dehydrated biological samples were investigated using transmission technique. Biological samples (onion membrane, egg coat and tomato coat) with different mass thickness were studied, together with mylar for comparison, in this work. The energy loss and energy straggling of MeV H and He ions after penetrating from the biological and mylar samples were measured. The experimental results show that the average energy losses of MeV ions through the biological samples are consistent with SRIM predictions, however, large deviation in energy straggling is observed between the measured result and the SRIM predictions. Taking into account inhomogeneity in mass density and structure of the biological sample, an energy straggling formula is suggested, and the experimental energy straggling values are well predicated by the proposed formula.

  17. Gravity resonance spectroscopy constrains dark energy and dark matter scenarios.

    PubMed

    Jenke, T; Cronenberg, G; Burgdörfer, J; Chizhova, L A; Geltenbort, P; Ivanov, A N; Lauer, T; Lins, T; Rotter, S; Saul, H; Schmidt, U; Abele, H

    2014-04-18

    We report on precision resonance spectroscopy measurements of quantum states of ultracold neutrons confined above the surface of a horizontal mirror by the gravity potential of Earth. Resonant transitions between several of the lowest quantum states are observed for the first time. These measurements demonstrate that Newton's inverse square law of gravity is understood at micron distances on an energy scale of 10-14  eV. At this level of precision, we are able to provide constraints on any possible gravitylike interaction. In particular, a dark energy chameleon field is excluded for values of the coupling constant β>5.8×108 at 95% confidence level (C.L.), and an attractive (repulsive) dark matter axionlike spin-mass coupling is excluded for the coupling strength gsgp>3.7×10-16 (5.3×10-16) at a Yukawa length of λ=20  μm (95% C.L.). PMID:24785025

  18. Friction-induced energy-loss rainbows in atom surface scattering.

    PubMed

    Moix, Jeremy M; Pollak, Eli; Miret-Artés, Salvador

    2010-03-19

    The rainbow is due to extrema of the angular deflection function of light impinging on water drops. Generically, extrema of suitably defined deflection functions lead to rainbows. These include angular and rotational rainbows in surface scattering and more. Here we introduce the concept of an "energy-loss deflection function" for scattering of particles from a periodic surface whose extrema lead to a new form-the "energy-loss rainbow" which appears as multiple maxima in the final energy distribution of the scattered particle. Energy-loss rainbows are caused by frictional phonon effects which induce structure in the energy-loss distribution instead of "washing it out." We provide evidence that they have been observed in Ne scattering on self-assembled monolayers. PMID:20366489

  19. Synergy of inelastic and elastic energy loss. Temperature effects and electronic stopping power dependence

    DOE PAGESBeta

    Zarkadoula, Eva; Xue, Haizhou; Zhang, Yanwen; Weber, William J.

    2015-06-16

    A combination of an inelastic thermal spike model suitable for insulators and molecular dynamics simulations is used to study the effects of temperature and electronic energy loss on ion track formation, size and morphology in SrTiO3 systems with pre-existing disorder. We find temperature dependence of the ion track size. In addition, we find a threshold in the electronic energy loss for a given pre-existing defect concentration, which indicates a threshold in the synergy between the inelastic and elastic energy loss.

  20. On ionization energy losses of ultra-relativistic half-bare electron

    NASA Astrophysics Data System (ADS)

    Shul'ga, N. F.; Trofymenko, S. V.

    2012-11-01

    The problem of ionization energy losses of relativistic electron after its emission from substance into vacuum and subsequent traversal of thin dielectric plate is considered. It is shown that with the increase of distance between the plate and the substance the gradual increase of electron ionization energy losses in the plate from the value defined by Fermi formula to the value defined by Bethe-Bloch formula complemented by radiation contribution to ionization occurs. It is highlighted that such change of energy losses is defined by reconstruction of the field around the electron and may occur on macroscopic distances along its trajectory.

  1. Phase effect in the energy loss of hydrogen projectiles in zinc targets

    SciTech Connect

    Arnau, A.; Bauer, P.; Kastner, F.; Salin, A.; Ponce, V.H.; Fainstein, P.D.; Echenique, P.M.

    1994-03-01

    We present an experimental and theoretical study of the phase effect in the energy loss of fast hydrogen beams colliding with gas and solid zinc targets. The experiments show a maximum phase effect of 50% around 50 keV/u, the energy loss per atom in the solid target being smaller than in the gas target. An extensive theoretical study of all the processes contributing to the energy loss in the two phases shows that the experimental findings can be explained primarily by the screening of the projectile field by the valence electrons in the solid.

  2. Energy loss straggling in collisions of fast finite-size ions with atoms

    SciTech Connect

    Makarov, D. N. Matveev, V. I.

    2013-03-15

    The influence of ion size on straggling of energy losses by fast partially stripped ions is studied using the nonperturbative approach based on the eikonal approximation. It is shown that such a consideration of collisions of ions with complex atoms can lead to considerable corrections in calculating root-mean-square straggling of energy losses by fast ions compared to the results obtained for point ions. The root-mean-square straggling of energy losses are calculated for bromide and iodine ions in collisions with copper, silver, and aluminum atoms. It is shown that allowance for the size of the electron 'coat' of an ion noticeably improves the agreement with experimental data.

  3. Synergy of inelastic and elastic energy loss. Temperature effects and electronic stopping power dependence

    SciTech Connect

    Zarkadoula, Eva; Xue, Haizhou; Zhang, Yanwen; Weber, William J.

    2015-06-16

    A combination of an inelastic thermal spike model suitable for insulators and molecular dynamics simulations is used to study the effects of temperature and electronic energy loss on ion track formation, size and morphology in SrTiO3 systems with pre-existing disorder. We find temperature dependence of the ion track size. In addition, we find a threshold in the electronic energy loss for a given pre-existing defect concentration, which indicates a threshold in the synergy between the inelastic and elastic energy loss.

  4. Energy loss partitioning during ballistic impact of polymer composites

    NASA Technical Reports Server (NTRS)

    Zee, Ralph H.; Hsieh, Chung Y.

    1993-01-01

    The objective of this study is to determine the energy dissipation processes in polymer-matrix composites during impact of ballistic projectiles. These processes include heat, fiber deformation and breakage, matrix deformation and fracture, and interfacial delamination. In this study, experimental measurements were made, using specialized specimen designs and test methods, to isolate the energy consumed by each of these processes during impact in the ballistic range. Using these experiments, relationships between material parameters and energy dissipation were examined. Composites with the same matrix but reinforced with Kevlar, PE, and graphite fabric were included in this study. These fibers were selected based on the differences in their intrinsic properties. Matrix cracking was found to be one of the most important energy absorption mechanisms during impact, especially in ductile samples such as Spectra-900 PE and Kevlar-49 reinforced polymer. On the contrary, delamination dominated the energy dissipation in brittle composites such as graphite reinforced materials. The contribution from frictional forces was also investigated and the energy partitioning among the different processes evaluated.

  5. Energy-efficient MRF clutch avoiding no-load losses

    NASA Astrophysics Data System (ADS)

    Güth, Dirk; Schamoni, Markus; Maas, Jürgen

    2013-04-01

    A challenge opposing a commercial use of actuators like brakes and clutches based on magnetorheological fluids (MRF) are durable no-load losses. A complete torque-free separation of these actuators is inherently not yet possible due to the permanent liquid intervention for the fluid engaging parts. Especially for applications with high rotational speeds up to some thousand RPM, this drawback of MRF actuators is not acceptable. In this paper, a novel approach will be presented that allows a controlled movement of the MRF from a torque-transmitting volume of the shear gap into an inactive volume of the shear gap, enabling a complete separation of the fluid engaging surfaces. This behavior is modeled for a novel clutch design by the use of the ferrohydrodynamics and therefore simulations are performed to investigate the transitions between engaged and idle mode. Measurements performed with a realized clutch show that the viscous induced drag torque can be reduced significantly.

  6. Energy balance and the composition of weight loss during prolonged space flight

    NASA Technical Reports Server (NTRS)

    Leonard, J. I.

    1982-01-01

    Integrated metabolic balance analysis, Skylab integrated metabolic balance analysis and computer simulation of fluid-electrolyte responses to zero-g, overall mission weight and tissue losses, energy balance, diet and exercise, continuous changes, electrolyte losses, caloric and exercise requirements, and body composition are discussed.

  7. Hysteresis of sextupole and ac loss in Energy Doubler dipole magnets

    SciTech Connect

    Ishibashi, K.

    1982-06-18

    A simple model gave utilized for calculation of magnetization effects on ac loss and sextupole for Energy Doubler dipole magnets. The calculation in the simple model gave an underestimation of ac loss by about 30%. Results of computation on ac harmonics were also described.

  8. Calculation of the first four moments of electronic energy loss of protons in insulators

    NASA Astrophysics Data System (ADS)

    Biersack, J. P.

    2000-05-01

    A novel scheme is presented for obtaining energy loss distributions for protons slowing-down in metals and bandgap materials. This scheme is here applied mainly to compare electronic energy loss distributions at low velocities, where the bandgap is most effective (projectile velocity less than Fermi velocity, venergy loss is governed by the Pauli principle which leads immediately to the results that the energy loss moments Mn, n=1,…,4, change proportionally to the nth power of projectile velocity, Wn=dMn/dx=Cn∗vn, in metals (no band gap), and they are due to the energy transfers to conduction electrons only. In bandgap materials, the smallest energy transfers cannot occur, and all energy loss moments Wn are thus reduced. Only at velocities near the Fermi velocity, the valence electrons reach nearly the same level as the conduction electrons in a metal, and at this velocity also the inner shell electrons begin to contribute, so that the stopping power (the first moment of energy loss) reaches its maximum above vF. At higher velocities, we find that the moments Mn increase proportionally to the (n-2)th power of projectile energy, Wn=dMn/dx=Cn∗En-2,n>1. The stopping power (n=1, first moment of energy loss) comes very close to the predictions of Bethe or Bloch. At low velocities, all energy transfers are reduced considerably by the presence of a bandgap, and differ greatly from metals. Despite of using some simplifications, the results obtained for lithium metal and for the bandgap material diamond agree quite well with recent experimental findings.

  9. Probing the electronic and spintronic properties of buried interfaces by extremely low energy photoemission spectroscopy

    PubMed Central

    Fetzer, Roman; Stadtmüller, Benjamin; Ohdaira, Yusuke; Naganuma, Hiroshi; Oogane, Mikihiko; Ando, Yasuo; Taira, Tomoyuki; Uemura, Tetsuya; Yamamoto, Masafumi; Aeschlimann, Martin; Cinchetti, Mirko

    2015-01-01

    Ultraviolet photoemission spectroscopy (UPS) is a powerful tool to study the electronic spin and symmetry features at both surfaces and interfaces to ultrathin top layers. However, the very low mean free path of the photoelectrons usually prevents a direct access to the properties of buried interfaces. The latter are of particular interest since they crucially influence the performance of spintronic devices like magnetic tunnel junctions (MTJs). Here, we introduce spin-resolved extremely low energy photoemission spectroscopy (ELEPS) to provide a powerful way for overcoming this limitation. We apply ELEPS to the interface formed between the half-metallic Heusler compound Co2MnSi and the insulator MgO, prepared as in state-of-the-art Co2MnSi/MgO-based MTJs. The high accordance between the spintronic fingerprint of the free Co2MnSi surface and the Co2MnSi/MgO interface buried below up to 4 nm MgO provides clear evidence for the high interface sensitivity of ELEPS to buried interfaces. Although the absolute values of the interface spin polarization are well below 100%, the now accessible spin- and symmetry-resolved wave functions are in line with the predicted existence of non-collinear spin moments at the Co2MnSi/MgO interface, one of the mechanisms evoked to explain the controversially discussed performance loss of Heusler-based MTJs at room temperature. PMID:25702631

  10. Probing the electronic and spintronic properties of buried interfaces by extremely low energy photoemission spectroscopy.

    PubMed

    Fetzer, Roman; Stadtmüller, Benjamin; Ohdaira, Yusuke; Naganuma, Hiroshi; Oogane, Mikihiko; Ando, Yasuo; Taira, Tomoyuki; Uemura, Tetsuya; Yamamoto, Masafumi; Aeschlimann, Martin; Cinchetti, Mirko

    2015-01-01

    Ultraviolet photoemission spectroscopy (UPS) is a powerful tool to study the electronic spin and symmetry features at both surfaces and interfaces to ultrathin top layers. However, the very low mean free path of the photoelectrons usually prevents a direct access to the properties of buried interfaces. The latter are of particular interest since they crucially influence the performance of spintronic devices like magnetic tunnel junctions (MTJs). Here, we introduce spin-resolved extremely low energy photoemission spectroscopy (ELEPS) to provide a powerful way for overcoming this limitation. We apply ELEPS to the interface formed between the half-metallic Heusler compound Co2MnSi and the insulator MgO, prepared as in state-of-the-art Co2MnSi/MgO-based MTJs. The high accordance between the spintronic fingerprint of the free Co2MnSi surface and the Co2MnSi/MgO interface buried below up to 4 nm MgO provides clear evidence for the high interface sensitivity of ELEPS to buried interfaces. Although the absolute values of the interface spin polarization are well below 100%, the now accessible spin- and symmetry-resolved wave functions are in line with the predicted existence of non-collinear spin moments at the Co2MnSi/MgO interface, one of the mechanisms evoked to explain the controversially discussed performance loss of Heusler-based MTJs at room temperature. PMID:25702631

  11. Effect of surface topography on reflection electron energy loss plasmon spectra of group III metals

    SciTech Connect

    Strawbridge, B.; Singh, R. K.; Beach, C.; Mahajan, S.; Newman, N.

    2006-09-15

    In situ reflection electron energy loss spectroscopy (REELS) and reflection high energy electron diffraction employing a 20 keV electron beam at a 2 deg. grazing angle were used to characterize the surface properties of molecular beam epitaxy (MBE) grown Al, Ga, and In metals on silicon and sapphire substrates. In our study we found that the surface topography strongly influences the REELS plasmon spectra. Smooth Al films with <1 nm rms roughness exhibited surface plasmon peaks. Both surface and bulk plasmons are seen from an Al film with a rms roughness of 3.5 nm. Aluminum surfaces with >5 nm rms roughness yielded only bulk plasmon peaks. To understand the EELS spectrum for the Ga and In films, the rms roughness alone is not the relevant figure of merit as the electron beam interaction with the surface is influenced most by the shape of the tops of the surface grains and the grain size. Indium films on Si with a rms roughness of 52 nm were found to excite predominantly surface plasmons as the grazing angle electron beam scattered mostly off the flat top surface of each grain and was not strongly influenced by the crevices between the grains. The rounded tops of the Ga topography with 31 nm rms roughness facilitated transmission through the grains and therefore excited a combination of bulk and surface plasmons. This experimental method is very surface sensitive, as a probe depth of 0.8 nm was inferred from the diminishing intensity of the substrate peak with increasing coverage of a flat metal surface. The techniques and methods discussed here can be readily applied to other thin film systems such as MBE-grown III-V semiconductors, sputtered oxides, and other vacuum deposited materials.

  12. Zero Kinetic Energy Photoelectron Spectroscopy of Benzo[h]quinoline.

    PubMed

    Harthcock, Colin; Zhang, Jie; Kong, Wei

    2015-12-17

    We report zero kinetic energy (ZEKE) photoelectron spectroscopy of benzo[h]quinoline (BhQ) via resonantly enhanced multiphoton ionization (REMPI) through the first electronically excited state S1. From the simulated REMPI spectra with and without Herzberg-Teller coupling, we conclude that vibronic coupling plays a minor but observable role in the electronic excitation to the S1 state. We further compare the S1 state of BhQ with the first two electronically excited states of phenanthrene, noticing a similarity of the S1 state of BhQ with the second electronically excited state S2 of phenanthrene. In the ZEKE spectra of BhQ, the vibrational frequencies of the cationic state D0 are consistently higher than those of the intermediate neutral state, indicating enhanced bonding upon ionization. The sparse ZEKE spectra, compared with the spectrum of phenanthrene containing rich vibronic activities, further imply that the nitrogen atom has attenuated the structural change between S1 and D0 states. We speculate that the nitrogen atom can withdraw an electron in the S1 state and donate an electron in the D0 state, thereby minimizing the structural change during ionization. The origin of the first electronically excited state is determined to be 29,410 ± 5 cm(-1), and the adiabatic ionization potential is determined to be 65,064 ± 7 cm(-1). PMID:26039927

  13. 13C NMR spectroscopy applications to brain energy metabolism

    PubMed Central

    Rodrigues, Tiago B.; Valette, Julien; Bouzier-Sore, Anne-Karine

    2013-01-01

    13C nuclear magnetic resonance (NMR) spectroscopy is the method of choice for studying brain metabolism. Indeed, the most convincing data obtained to decipher metabolic exchanges between neurons and astrocytes have been obtained using this technique, thus illustrating its power. It may be difficult for non-specialists, however, to grasp thefull implication of data presented in articles written by spectroscopists. The aim of the review is, therefore, to provide a fundamental understanding of this topic to facilitate the non-specialists in their reading of this literature. In the first part of this review, we present the metabolic fate of 13C-labeled substrates in the brain in a detailed way, including an overview of some general neurochemical principles. We also address and compare the various spectroscopic strategies that can be used to study brain metabolism. Then, we provide an overview of the 13C NMR experiments performed to analyze both intracellular and intercellular metabolic fluxes. More particularly, the role of lactate as a potential energy substrate for neurons is discussed in the light of 13C NMR data. Finally, new perspectives and applications offered by 13C hyperpolarization are described. PMID:24367329

  14. Fast ion surface energy loss and straggling in the surface wake fields.

    PubMed

    Nandi, T; Haris, K; Hala; Singh, Gurjeet; Kumar, Pankaj; Kumar, Rajesh; Saini, S K; Khan, S A; Jhingan, Akhil; Verma, P; Tauheed, A; Mehta, D; Berry, H G

    2013-04-19

    We have measured the stopping powers and straggling of fast, highly ionized atoms passing through thin bilayer targets made up of metals and insulators. We were surprised to find that the energy losses as well as the straggling depend on the ordering of the target and have small but significantly different values on bilayer reversal. We ascribe this newly found difference in energy loss to the surface energy loss field effect due to the differing surface wake fields as the beam exits the target in the two cases. This finding is validated with experiments using several different projectiles, velocities, and bilayer targets. Both partners of the diatomic molecular ions also display similar results. A comparison of the energy loss results with those of previous theoretical predictions for the surface wake potential for fast ions in solids supports the existence of a self-wake. PMID:23821777

  15. Understanding energy loss in parallelly connected microbial fuel cells: Non-Faradaic current.

    PubMed

    An, Junyeong; Sim, Junyoung; Feng, Yujie; Lee, Hyung-Sool

    2016-03-01

    In this work, the mechanisms of energy loss in parallel connection of microbial fuel cells (MFCs) is explored using two MFC units producing different open circuit voltage (OCV) and current. In open circuit mode, non-Faradaic current flows in low OCV unit, implying energy loss caused by different OCVs in parallelly stacked MFCs. In a stacked MFC in parallel under close circuit mode, it is confirmed that energy loss occurs until the working voltage in high OCV unit becomes identical to the other unit having low OCV. This result indicates that different voltage between individual MFC units can cause energy loss due to both non-Faradic and Faradaic current that flow from high voltage unit to low voltage unit even in parallelly stacked MFCs. PMID:26744801

  16. Calculation of the energy loss for an electron passing near giant fullerenes

    NASA Astrophysics Data System (ADS)

    Henrard, L.; Lambin, Ph

    1996-11-01

    We present a theoretical analysis of the electron energy-loss spectra of isolated giant fullerenes. We use a macroscopic dielectric description of spherical onion-like fullerenes and a discrete dipole approximation (DDA) framework for tubular fullerenes. In the DDA model, an anisotropic dynamical polarizability is assigned to each carbon site. We stress the fundamental importance of the hollow character of giant fullerenes in the electron energy-loss resonances.

  17. Baryon kinetic energy loss in the color flux tube model

    NASA Astrophysics Data System (ADS)

    Lyakhov, K. A.; Lee, H. J.

    2011-11-01

    One possible scenario of chromofield decay in its initial stage of evolution is Schwinger's mechanism in restricted volume. It is assumed that initial chromofield energy can be represented as a collection of color flux tubes (CFT) stretched between receding nuclei. CFT expands up to some length until its breakup followed by the production of soft partons. A new formula for initial chromofield energy density is derived from the MacLerran-Venugopalan model to calculate CFT tension. It considers two possible ansatzes for saturation momentum. Color charge screening by produced partons is taken into account as well. A new formula for evolution of produced parton multiplicities based on the Wigner representation of the phase-space density of probability is also derived.

  18. Non-Abelian energy loss at finite opacity.

    PubMed

    Gyulassy, M; Levai, P; Vitev, I

    2000-12-25

    A systematic expansion in opacity, L/lambda, is used to clarify the nonlinear behavior of induced gluon radiation in quark-gluon plasmas. The inclusive differential gluon distribution is calculated up to second order in opacity and compared to the zeroth order (factorization) limit. The opacity expansion makes it possible to take finite kinematic constraints into account that suppress jet quenching in nuclear collisions below RHIC (square root of s = 200 AGeV) energies. PMID:11136040

  19. Energy losses at three-way circular drop manholes under surcharged conditions.

    PubMed

    Arao, Shinji; Kusuda, Tetsuya; Moriyama, Katsumi; Hiratsuka, Shunsuke; Asada, Jyunsaku; Hirose, Nozomu

    2012-01-01

    Energy loss at manholes is of importance in the design of storm sewer networks and in flood-analysis. Some researchers have already investigated the energy loss at three-way manholes under surcharged conditions. However, formulation to calculate the energy loss at manholes, including all variables of structural elements of the pipes and of the manhole has not yet been accomplished. Therefore, more study to formulate the energy loss at three-way drop manholes is needed. In this study, the ratio of the diameter between inflow pipes and an outflow pipe, the ratio of flow rates between those pipes, water depth in a manhole and the drop gaps between those pipes are considered and the energy loss at three-way circular drop manholes is examined. Finally, a modified formula, more accurate than that in the U.S. Federal Highway Administration's 2001 Urban Drainage Design Manual is proposed. The proposed formula takes the influence of the ratio of the diameter between inflow pipes and outflow pipe and drop gaps between those pipes into consideration. The calculated energy loss coefficients in both straight-through and lateral pipes successfully reproduce the measured values. PMID:22678199

  20. Energy loss of ions by electric-field fluctuations in a magnetized plasma

    SciTech Connect

    Nersisyan, Hrachya B.; Deutsch, Claude

    2011-06-15

    The results of a theoretical investigation of the energy loss of charged particles in a magnetized classical plasma due to the electric-field fluctuations are reported. The energy loss for a test particle is calculated through the linear-response theory. At vanishing magnetic field, the electric-field fluctuations lead to an energy gain of the charged particle for all velocities. It has been shown that in the presence of strong magnetic field, this effect occurs only at low velocities. In the case of high velocities, the test particle systematically loses its energy due to the interaction with a stochastic electric field. The net effect of the fluctuations is the systematic reduction of the total energy loss (i.e., the sum of the polarization and stochastic energy losses) at vanishing magnetic field and reduction or enhancement at strong field, depending on the velocity of the particle. It is found that the energy loss of the slow heavy ion contains an anomalous term that depends logarithmically on the projectile mass. The physical origin of this anomalous term is the coupling between the cyclotron motion of the plasma electrons and the long-wavelength, low-frequency fluctuations produced by the projectile ion. This effect may strongly enhance the stochastic energy gain of the particle.

  1. The energy-dependent electron loss model for pencil beam dose kernels

    NASA Astrophysics Data System (ADS)

    Chvetsov, Alexei V.; Sandison, George A.; Yeboah, Collins

    2000-10-01

    The `monoenergetic' electron loss model was derived in a previous work to account for pathlength straggling in the Fermi-Eyges pencil beam problem. In this paper, we extend this model to account for energy-loss straggling and secondary knock-on electron transport in order to adequately predict a depth dose curve. To model energy-loss straggling, we use a weighted superposition of a discrete number of monoenergetic pencil beams with different initial energies where electrons travel along the depth-energy characteristics in the continuous slowing down approximation (CSDA). The energy straggling spectrum at depth determines the weighting assigned to each monoenergetic pencil beam. Supplemented by a simple transport model for the secondary knock-on electrons, the `energy-dependent' electron loss model predicts both lateral and depth dose distributions from the electron pencil beams in good agreement with Monte Carlo calculations and measurements. The calculation of dose distribution from a pencil beam takes 0.2 s on a Pentium III 500 MHz computer. Being computationally fast, the `energy-dependent' electron loss model can be used for the calculation of 3D energy deposition kernels in dose optimization schemes without using precalculated or measured data.

  2. Reducing heat loss from the energy absorber of a solar collector

    DOEpatents

    Chao, Bei Tse; Rabl, Ari

    1976-01-01

    A device is provided for reducing convective heat loss in a cylindrical radiant energy collector. It includes a curved reflective wall in the shape of the arc of a circle positioned on the opposite side of the exit aperture from the reflective side walls of the collector. Radiant energy exiting the exit aperture is directed by the curved wall onto an energy absorber such that the portion of the absorber upon which the energy is directed faces downward to reduce convective heat loss from the absorber.

  3. Reduction of Thermal Energy Loss in Cyclic Operation of Refrigeration Cycle

    NASA Astrophysics Data System (ADS)

    Gommori, Masahiko; Kogure, Hiroshi; Hara, Toshitsugu

    Investigation of thermal energy loss in cyclic operation of refrigeration cycle in a refrigerator-freezer were made. The energy loss was found to consist of three parts ; hot gas-refrigerant entering loss, cooling lag loss, and evaporator superheat loss. Hot gas-refrigerant entering loss is occured when high temperature gaseous refrigerant in a condenser flows into an evaporator to heat up the refrigerant in it. Main results are as follows ; 1) Hot gas-refrigerant entering loss, which was the most dominant, was found to be from 7.6 to 12.3% (for reciprocationg compressor) and from 11.9 to 17.4% (for rotary compressor) of the cooling load, respectively. 2) The thermal energy loss was confirmed to be able to be reduced when hot gas-refrigerant was restricted to flow in the evaporator with control valves. It follows to reduce electrical power consumption by 10 and 15%, in the case of reciprocating compressor and of rotary compressor, respectively. 3) Cycle frequency was made to be optimized theoretically and experimentally in the case of with and without valves.

  4. AdS/CFT heavy quark energy loss beyond the leading order

    NASA Astrophysics Data System (ADS)

    Horowitz, W. A.

    2014-11-01

    Naïve, leading order, fully strongly-coupled AdS/CFT energy loss models are either falsified or put into significant doubt when constrained by RHIC and then compared to LHC data. The proper inclusion of fluctuations in heavy quark momentum loss leads to LHC predictions, constrained by RHIC, not in qualitative disagreement with measurements. Once renormalized, strong-coupling energy loss predictions for jet suppression with a new, physically motivated jet definition within AdS/CFT yields predictions in surprisingly good agreement with preliminary LHC results.

  5. Can limiting dietary variety assist with reducing energy intake and weight loss?☆

    PubMed Central

    Raynor, Hollie A.

    2013-01-01

    Due to the high prevalence of overweight and obesity, developing strategies to improve weight loss and weight loss maintenance is imperative. One dietary environmental variable that has received little attention in being targeted in an intervention to assist with obesity treatment is dietary variety. Experimental research has consistently shown that greater dietary variety increases consumption, with the effect of variety on consumption hypothesized to be a consequence of the differential experience of the more varied sensory properties of food under those conditions with greater dietary variety. As reduced energy intake is required for weight loss, limiting variety, particularly in food groups that are high in energy-density and low in nutrient-density, may assist with reducing energy intake and improving weight loss. A series of investigations, both observational and experimental, were conducted to examine if limiting variety in an energydense, non-nutrient-dense food group, snack foods (i.e., cookies, chips), assisted with reducing energy intake of the food group and improving weight loss. Results of the investigations suggest that a prescription for limiting variety in a food group can be implemented during obesity treatment, limiting variety is associated with the occurrence of monotony, and that reducing food group variety is related to decreased consumption of that food group. Future research is needed to ascertain the long-term effect of prescriptions targeting dietary variety on weight loss and weight loss maintenance. PMID:22450259

  6. Chimney-related energy losses in residential oil-fired heating systems

    SciTech Connect

    Butcher, T.; Celebi, Y.; Krajewski, R. ); Batey, J. )

    1990-01-01

    Conventional venting systems for oil-fired residential heating equipment include the flue connector, a barometric damper, and the chimney. This arrangement is directly responsible for some of the system energy losses, including a part of the off-cycle heat loss and infiltration losses. The magnitude of these losses depends upon the location of the unit, the chimney constuction, and the characteristics of the barometric damper and the burner. In the work described in this paper, a study of the characteristics of burners and dampers was done to permit these energy losses to be estimated as a function of the installation details. The purpose is to determine the energy savings that might be realized from alternative venting methods. Flows through the heating unit and barometric damper flows have been calculated during the on- and off-cycle for a range of configurations as a function of outdoor temperature. Based on these flows, an example of the annual energy losses due to the venting system was calculated using a bin method for a boiler. Generally, the benefits of reducing barometric damper flows are to a great degree offset by increased off-cycle losses in the case of boilers.

  7. Hydrodynamic evolution and jet energy loss in Cu + Cu collisions

    SciTech Connect

    Schenke, Bjoern; Jeon, Sangyong; Gale, Charles

    2011-04-15

    We present results from a hybrid description of Cu + Cu collisions using (3 + 1)-dimensional hydrodynamics (music) for the bulk evolution and a Monte Carlo simulation (martini) for the evolution of high-momentum partons in the hydrodynamical background. We explore the limits of this description by going to small system sizes and determine the dependence on different fractions of wounded nucleon and binary collisions scaling of the initial energy density. We find that Cu + Cu collisions are well described by the hybrid description at least up to 20% central collisions.

  8. A new beam loss detector for low-energy proton and heavy-ion accelerators

    NASA Astrophysics Data System (ADS)

    Liu, Zhengzheng; Crisp, Jenna; Russo, Tom; Webber, Robert; Zhang, Yan

    2014-12-01

    The Facility for Rare Isotope Beams (FRIB) to be constructed at Michigan State University shall deliver a continuous, 400 kW heavy ion beam to the isotope production target. This beam is capable of inflicting serious damage on accelerator components, e.g. superconducting RF accelerating cavities. A Beam Loss Monitoring (BLM) System is essential for detecting beam loss with sufficient sensitivity and promptness to inform the machine protection system (MPS) and operations personnel of impending dangerous losses. Radiation transport simulations reveal shortcomings in the use of ionization chambers for the detection of beam losses in low-energy, heavy-ion accelerators. Radiation cross-talk effects due to the folded geometry of the FRIB LINAC pose further complications to locating specific points of beam loss. We propose a newly developed device, named the Loss Monitor Ring (LMR1

  9. Hysteresis model and statistical interpretation of energy losses in non-oriented steels

    NASA Astrophysics Data System (ADS)

    Mănescu (Păltânea), Veronica; Păltânea, Gheorghe; Gavrilă, Horia

    2016-04-01

    In this paper the hysteresis energy losses in two non-oriented industrial steels (M400-65A and M800-65A) were determined, by means of an efficient classical Preisach model, which is based on the Pescetti-Biorci method for the identification of the Preisach density. The excess and the total energy losses were also determined, using a statistical framework, based on magnetic object theory. The hysteresis energy losses, in a non-oriented steel alloy, depend on the peak magnetic polarization and they can be computed using a Preisach model, due to the fact that in these materials there is a direct link between the elementary rectangular loops and the discontinuous character of the magnetization process (Barkhausen jumps). To determine the Preisach density it was necessary to measure the normal magnetization curve and the saturation hysteresis cycle. A system of equations was deduced and the Preisach density was calculated for a magnetic polarization of 1.5 T; then the hysteresis cycle was reconstructed. Using the same pattern for the Preisach distribution, it was computed the hysteresis cycle for 1 T. The classical losses were calculated using a well known formula and the excess energy losses were determined by means of the magnetic object theory. The total energy losses were mathematically reconstructed and compared with those, measured experimentally.

  10. Energy loss behavior of photo-generated multi-component carriers in GaN

    NASA Astrophysics Data System (ADS)

    Yi, Kyung-Soo; Kim, Hye Jung; Kim, Do-Kyun

    2014-03-01

    Temporal behavior and many-body effect on the energy losses of photo-generated electron-hole plasma in GaN are examined in terms of various carrier-phonon couplings. We report a comprehensive cooling behavior as a function of effective carrier temperature over the temperature range of 10 -1500 K for carrier-phonon couplings via polar and nonpolar optical phonons and piezoelectric and acoustic deformation-potentials. The many-body effect on the multi-component carrier polarizations and phonon spectral function and effect of energy reabsorption via hot phonons are included by employing temperature-dependent dynamic responses in the rpa. We show that, as the carrier temperature decreases, the energy losses via carrier-optical phonon couplings diminish rapidly and the carrier energy relaxation is dominated through the acoustic phonon scattering at low carrier energy. From the energy loss rates, energy cooling curves are obtained as a function of time, and our result shows an initial gentle energy relaxation followed by fast relaxation. Spectral analysis of the dielectric response functions and energy loss rates are also performed and their dynamic and nonlocal behavior will be discussed. This research was supported in part by Basic Science Research Program through the NRF funded by the Ministry of Education (grant number 201306330001).

  11. Determining the band gap and mean kinetic energy of atoms from reflection electron energy loss spectra

    SciTech Connect

    Vos, M.; Marmitt, G. G.; Finkelstein, Y.; Moreh, R.

    2015-09-14

    Reflection electron energy loss spectra from some insulating materials (CaCO{sub 3}, Li{sub 2}CO{sub 3}, and SiO{sub 2}) taken at relatively high incoming electron energies (5–40 keV) are analyzed. Here, one is bulk sensitive and a well-defined onset of inelastic excitations is observed from which one can infer the value of the band gap. An estimate of the band gap was obtained by fitting the spectra with a procedure that includes the recoil shift and recoil broadening affecting these measurements. The width of the elastic peak is directly connected to the mean kinetic energy of the atom in the material (Doppler broadening). The experimentally obtained mean kinetic energies of the O, C, Li, Ca, and Si atoms are compared with the calculated ones, and good agreement is found, especially if the effect of multiple scattering is taken into account. It is demonstrated experimentally that the onset of the inelastic excitation is also affected by Doppler broadening. Aided by this understanding, we can obtain a good fit of the elastic peak and the onset of inelastic excitations. For SiO{sub 2}, good agreement is obtained with the well-established value of the band gap (8.9 eV) only if it is assumed that the intensity near the edge scales as (E − E{sub gap}){sup 1.5}. For CaCO{sub 3}, the band gap obtained here (7 eV) is about 1 eV larger than the previous experimental value, whereas the value for Li{sub 2}CO{sub 3} (7.5 eV) is the first experimental estimate.

  12. Entropy Generation/Availability Energy Loss Analysis Inside MIT Gas Spring and "Two Space" Test Rigs

    NASA Technical Reports Server (NTRS)

    Ebiana, Asuquo B.; Savadekar, Rupesh T.; Patel, Kaushal V.

    2006-01-01

    The results of the entropy generation and availability energy loss analysis under conditions of oscillating pressure and oscillating helium gas flow in two Massachusetts Institute of Technology (MIT) test rigs piston-cylinder and piston-cylinder-heat exchanger are presented. Two solution domains, the gas spring (single-space) in the piston-cylinder test rig and the gas spring + heat exchanger (two-space) in the piston-cylinder-heat exchanger test rig are of interest. Sage and CFD-ACE+ commercial numerical codes are used to obtain 1-D and 2-D computer models, respectively, of each of the two solution domains and to simulate the oscillating gas flow and heat transfer effects in these domains. Second law analysis is used to characterize the entropy generation and availability energy losses inside the two solution domains. Internal and external entropy generation and availability energy loss results predicted by Sage and CFD-ACE+ are compared. Thermodynamic loss analysis of simple systems such as the MIT test rigs are often useful to understand some important features of complex pattern forming processes in more complex systems like the Stirling engine. This study is aimed at improving numerical codes for the prediction of thermodynamic losses via the development of a loss post-processor. The incorporation of loss post-processors in Stirling engine numerical codes will facilitate Stirling engine performance optimization. Loss analysis using entropy-generation rates due to heat and fluid flow is a relatively new technique for assessing component performance. It offers a deep insight into the flow phenomena, allows a more exact calculation of losses than is possible with traditional means involving the application of loss correlations and provides an effective tool for improving component and overall system performance.

  13. Synergy of elastic and inelastic energy loss on ion track formation in SrTiO₃.

    PubMed

    Weber, William J; Zarkadoula, Eva; Pakarinen, Olli H; Sachan, Ritesh; Chisholm, Matthew F; Liu, Peng; Xue, Haizhou; Jin, Ke; Zhang, Yanwen

    2015-01-01

    While the interaction of energetic ions with solids is well known to result in inelastic energy loss to electrons and elastic energy loss to atomic nuclei in the solid, the coupled effects of these energy losses on defect production, nanostructure evolution and phase transformations in ionic and covalently bonded materials are complex and not well understood due to dependencies on electron-electron scattering processes, electron-phonon coupling, localized electronic excitations, diffusivity of charged defects, and solid-state radiolysis. Here we show that a colossal synergy occurs between inelastic energy loss and pre-existing atomic defects created by elastic energy loss in single crystal strontium titanate (SrTiO₃), resulting in the formation of nanometer-sized amorphous tracks, but only in the narrow region with pre-existing defects. These defects locally decrease the electronic and atomic thermal conductivities and increase electron-phonon coupling, which locally increase the intensity of the thermal spike for each ion. This work identifies a major gap in understanding on the role of defects in electronic energy dissipation and electron-phonon coupling; it also provides insights for creating novel interfaces and nanostructures to functionalize thin film structures, including tunable electronic, ionic, magnetic and optical properties. PMID:25578009

  14. Energy loss straggling of low energy alpha particles in a medium composed of polyatomic and diatomic molecules

    NASA Astrophysics Data System (ADS)

    Milošević, Z.; Novković, D.; Subotić, K.

    1996-08-01

    The results of the measurement of the energy straggling of low energy alpha particles in the polyatomic and diatomic molecule media are reported. A general analytical formula for straggling widths of light ions, obtained by solving Symon's equation for the second and third order central moments of the straggling distributions in non-relativistic approximation, has shown remarkably good agreement with experimental data at energy losses less than 70% of the initial projectile energies.

  15. Low or moderate dietary energy restriction for long-term weight loss: what works best?

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Theoretical calculations suggest that small daily reductions in energy intake can cumulatively lead to substantial weight loss, but experimental data to support these calculations are lacking. We conducted a 1-year randomized controlled pilot study of low (10%) or moderate (30%) energy restriction (...

  16. CEBAF at higher energies: Working group report on hadron spectroscopy and production

    SciTech Connect

    Barnes, T. |; Napolitano, J.

    1994-04-01

    This report summarizes topics in hadron spectroscopy and production which could be addressed at CEBAF with an energy upgrade to E{sub {gamma}} = 8 GeV and beyond. The topics discussed include conventional meson and baryon spectrocopy, spectroscopy of exotica (especially molecules and hybrids), CP and CPT tests using {phi} mesons, and new detector and accelerator options.

  17. Transverse momentum diffusion and collisional jet energy loss in non-Abelian plasmas

    SciTech Connect

    Schenke, Bjoern; Strickland, Michael; Dumitru, Adrian; Nara, Yasushi; Greiner, Carsten

    2009-03-15

    We consider momentum broadening and energy loss of high-momentum partons in a hot non-Abelian plasma due to collisions. We solve the coupled system of Wong-Yang-Mills equations on a lattice in real time, including binary hard elastic collisions among the partons. The collision kernel is constructed such that the total collisional energy loss and momentum broadening are lattice-spacing independent. We find that the transport coefficient q corresponding to transverse momentum broadening receives sizable contributions from a power-law tail in the p{sub perpendicular} distribution of high-momentum partons. We establish the scaling of q and of dE/dx with density, temperature, and energy in the weak-coupling regime. We also estimate the nuclear modification factor R{sub AA} due to elastic energy loss of a jet in a classical Yang-Mills field.

  18. Energy loss straggling in Aluminium foils for Li and C ions in fractional energy loss limits (ΔE/E) ∼10-60%

    NASA Astrophysics Data System (ADS)

    Diwan, P. K.; Kumar, Sunil; Kumar, Shyam; Sharma, V.; Khan, S. A.; Avasthi, D. K.

    2016-02-01

    The energy loss straggling of Li and C ions in Al foils of various thicknesses has been measured, within the fractional energy loss limit (∆E/E) ∼ 10-60%. These measurements have been performed using the 15UD Pelletron accelerator facility available at Inter University Accelerator Centre (IUAC), New Delhi, India. The measured straggling values have been compared with the corresponding predicted values adopting popularly used collisional straggling formulations viz Bohr, Lindhard and Scharff, Bethe-Livingston, Titeica. In addition, the experimental data has been compared to the Yang et al. empirical formula and Close Form Model, recently proposed by Montanari et al. The straggling values derived by Titeica theory were found to be in better agreement with the measured values as compared to other straggling formulations. The charge-exchange straggling component has been estimated from the measured data based on Titeica's theory. Finally, a function of the ion effective charge and the energy loss fraction within the target has been fitted to the latter straggling component.

  19. Impact of potassium doping on the electronic structure of tetracene and pentacene: An electron energy-loss study.

    PubMed

    Roth, Friedrich; Knupfer, Martin

    2015-10-21

    We report the doping induced changes of the electronic structure of tetracene and pentacene probed by electron energy-loss spectroscopy in transmission. A comparison between the dynamic response of undoped and potassium-intercalated tetracene and pentacene emphasizes the appearance of a new excitation feature in the former gap upon potassium addition. Interestingly, the momentum dependency of this new excitation shows a negative dispersion. Moreover, the analysis of the C 1s and K 2p core-level excitation results in a significantly lower doping level compared to potassium doped picene, a recently discovered superconductor. Therefore, the present electronic structure investigations open a new pathway to better understand the exceptional differences between acenes and phenacene and their divergent behavior upon alkali doping. PMID:26493923

  20. Impact of potassium doping on the electronic structure of tetracene and pentacene: An electron energy-loss study

    NASA Astrophysics Data System (ADS)

    Roth, Friedrich; Knupfer, Martin

    2015-10-01

    We report the doping induced changes of the electronic structure of tetracene and pentacene probed by electron energy-loss spectroscopy in transmission. A comparison between the dynamic response of undoped and potassium-intercalated tetracene and pentacene emphasizes the appearance of a new excitation feature in the former gap upon potassium addition. Interestingly, the momentum dependency of this new excitation shows a negative dispersion. Moreover, the analysis of the C 1s and K 2p core-level excitation results in a significantly lower doping level compared to potassium doped picene, a recently discovered superconductor. Therefore, the present electronic structure investigations open a new pathway to better understand the exceptional differences between acenes and phenacene and their divergent behavior upon alkali doping.

  1. Impact of potassium doping on the electronic structure of tetracene and pentacene: An electron energy-loss study

    SciTech Connect

    Roth, Friedrich

    2015-10-21

    We report the doping induced changes of the electronic structure of tetracene and pentacene probed by electron energy-loss spectroscopy in transmission. A comparison between the dynamic response of undoped and potassium-intercalated tetracene and pentacene emphasizes the appearance of a new excitation feature in the former gap upon potassium addition. Interestingly, the momentum dependency of this new excitation shows a negative dispersion. Moreover, the analysis of the C 1s and K 2p core-level excitation results in a significantly lower doping level compared to potassium doped picene, a recently discovered superconductor. Therefore, the present electronic structure investigations open a new pathway to better understand the exceptional differences between acenes and phenacene and their divergent behavior upon alkali doping.

  2. Resonant gate driver with efficient gate energy recovery and switching loss reduction

    NASA Astrophysics Data System (ADS)

    Kim, I.-G.; Kwak, S.-S.

    2016-04-01

    This article describes a novel resonant gate driver for charging the gate capacitor of power metal-oxide semiconductor field-effect-transistors (MOSFETs) that operate at a high switching frequency in power converters. The proposed resonant gate driver is designed with three small MOSFETs to build up the inductor current in addition to an inductor for temporary energy storage. The proposed resonant gate driver recovers the CV2 gate loss, which is the largest loss dissipated in the gate resistance in conventional gate drivers. In addition, the switching loss is reduced at the instants of turn on and turn off in the power MOSFETs of power converters by using the proposed gate driver. Mathematical analyses of the total loss appearing in the gate driver circuit and the switching loss reduction in the power switch of power converters are discussed. Finally, the proposed resonant gate driver is verified with experimental results at a switching frequency of 1 MHz.

  3. Reduction of ELM energy loss by pellet injection for ELM pacing

    NASA Astrophysics Data System (ADS)

    Hayashi, N.; Aiba, N.; Takizuka, T.; Oyama, N.

    2013-12-01

    The energy loss caused by the edge-localized mode (ELM) needs to be reduced for ITER operations with ELMy H-mode plasmas. The reduction in ELM energy loss by pellet injection for ELM pacing is studied by an integrated core/scrape-off layer/divertor transport code TOPICS-IB with a magnetohydrodynamic stability code and a pellet model taking account of the E × B drift of the pellet plasma cloud. It is found that the energy loss can be significantly reduced by a pellet injected to the pedestal plasma equivalent to that at the middle timing in the natural ELM cycle, whose pressure height is only about 5% lower than that of the natural ELM onset. In this case, pellet injection from the low-field side enables a small pellet, with about 1-2% of pedestal particle content and a speed high enough to approach the pedestal top, to reduce the energy loss significantly. With the above suitable conditions for ELM pacing, a pellet penetrates deep into the pedestal and triggers high-n ballooning modes with localized eigenfunctions near the pedestal top, where n is the toroidal mode number. Under suitable conditions, ELM pacing with reduced energy loss is successfully demonstrated in simulations, in which the gas puff reduction and the enhancement of divertor pumping can compensate for the core density increase due to additional particle fuelling by the pacing pellet.

  4. Production of metastable Ar[sup +] ions by electron-impact ionization of Ar measured by translational-energy spectroscopy

    SciTech Connect

    Kamber, E.Y. ); Enos, C.S.; Brenton, A.G. )

    1993-07-01

    The translational-energy-spectroscopy technique has been used to measure the apparent ionization-excitation functions for the metastable states 3 [sup 4]D, 3[ital d] [sup 4]F, 3[ital d] [sup 2]F, and 3[ital d][prime] [sup 2][ital F] of an Ar[sup +] ion beam extracted from an electron-impact ion source. The initial states were identified from the measured energy loss in the translational-energy spectra for single-electron stripping from ground-state and metastable Ar[sup +] ions in collisions with O[sub 2]. This technique provides an alternative method of selectivity in the study of electron-impact ionization and excitation processes.

  5. A. C. losses in the SSC high energy booster dipole magnets

    SciTech Connect

    Jayakumar, R.; Kovachev, V.; Snitchler, G.; Orrell, D.

    1991-06-01

    The baseline design for the SSC High Energy Booster (HEB) has dipole bending magnets with a 50 mm aperture. An analysis of the cryogenic heat load due to A.C. losses generated in the HEB ramp cycle are reported for this magnet. Included in this analysis are losses from superconductor hysteresis, yoke hysteresis, strand eddy currents, and cable eddy currents. The A.C. loss impact of 2.5 {mu}m vs. 6 {mu}m filament conductor is presented. A 60 mm aperture design is also investigated. 8 refs., 3 tabs.

  6. Athermal Energy Loss from X-rays Deposited in Thin Superconducting Films on Solid Substrates

    NASA Technical Reports Server (NTRS)

    Kozorezov, Alexander G.; Lambert, Colin J.; Bandler, Simon R.; Balvin, Manuel A.; Busch, Sarah E.; Sagler, Peter N.; Porst, Jan-Patrick; Smith, Stephen J.; Stevenson, Thomas R.; Sadleir, John E.

    2013-01-01

    When energy is deposited in a thin-film cryogenic detector, such as from the absorption of an X-ray, an important feature that determines the energy resolution is the amount of athermal energy that can be lost to the heat bath prior to the elementary excitation systems coming into thermal equilibrium. This form of energy loss will be position-dependent and therefore can limit the detector energy resolution. An understanding of the physical processes that occur when elementary excitations are generated in metal films on dielectric substrates is important for the design and optimization of a number of different types of low temperature detector. We have measured the total energy loss in one relatively simple geometry that allows us to study these processes and compare measurements with calculation based upon a model for the various di.erent processes. We have modeled the athermal phonon energy loss in this device by finding an evolving phonon distribution function that solves the system of kinetic equations for the interacting system of electrons and phonons. Using measurements of device parameters such as the Debye energy and the thermal di.usivity we have calculated the expected energy loss from this detector geometry, and also the position-dependent variation of this loss. We have also calculated the predicted impact on measured spectral line-shapes, and shown that they agree well with measurements. In addition, we have tested this model by using it to predict the performance of a number of other types of detector with di.erent geometries, where good agreement is also found.

  7. Hypochlorous acid-promoted loss of metabolic energy in Escherichia coli

    SciTech Connect

    Barrette, W.C. Jr.; Albrich, J.M.; Hurst, J.K.

    1987-10-01

    Oxidation of Escherichia coli by hypochlorous acid (HOCl) or chloramine (NH/sub 2/Cl) gives rise to massive hydrolysis of cytosolic nucleotide phosphoanhydride bonds, although no immediate change occurs in either the nucleotide pool size or the concentrations of extracellular end products of AMP catabolism. Titrimetric curves of the extent of hydrolysis coincide with curves for loss of cell viability, e.g., reduction in the adenylate energy charge from 0.8 to 0.1-0.2 accompanies loss of 99% of the bacterial CFU. The oxidative damage caused by HOCl is irreversible within 100 ms of exposure of the organism, although nucleotide phosphate bond hydrolysis requires several minutes to reach completion. Neither HOCl nor NH/sub 2/Cl reacts directly with nucleotides to hydrolyze phosphoanhydride bonds. Loss of viability is also accompanied by inhibition of induction of beta-galactosidase. The proton motive force, determined from the distribution of /sup 14/C-radiolabeled lipophilic ions, declines with incremental addition of HOCl after loss of respiratory function; severalfold more oxidant is required for the dissipation of the proton motive force than for loss of viability. These observations establish a causal link between loss of metabolic energy and cellular death and indicate that the mechanisms of oxidant-induced nucleotide phosphate bond hydrolysis are indirect and that they probably involve damage to the energy-transducing and transport proteins located in the bacterial plasma membrane.

  8. Energy homeostasis and appetite regulating hormones as predictors of weight loss in men and women.

    PubMed

    Williams, Rebecca L; Wood, Lisa G; Collins, Clare E; Morgan, Philip J; Callister, Robin

    2016-06-01

    Sex differences in weight loss are often seen despite using the same weight loss program. There has been relatively little investigation of physiological influences on weight loss success in males and females, such as energy homeostasis and appetite regulating hormones. The aims were to 1) characterise baseline plasma leptin, ghrelin and adiponectin concentrations in overweight and obese males and females, and 2) determine whether baseline concentrations of these hormones predict weight loss in males and females. Subjects were overweight or obese (BMI 25-40 kg/m(2)) adults aged 18-60 years. Weight was measured at baseline, and after three and six months participation in a weight loss program. Baseline concentrations of leptin, adiponectin and ghrelin were determined by enzyme-linked immunosorbent assay (ELISA). An independent t-test or non-parametric equivalent was used to determine any differences between sex. Linear regression determined whether baseline hormone concentrations were predictors of six-month weight change. Females had significantly higher baseline concentrations of leptin, adiponectin and unacylated ghrelin as well as ratios of leptin:adiponectin and leptin:ghrelin. The ratio of acylated:unacylated ghrelin was significantly higher in males. In males and females, a higher baseline concentration of unacylated ghrelin predicted greater weight loss at six months. Additionally in females, higher baseline total ghrelin predicted greater weight loss and a higher ratio of leptin:ghrelin predicted weight gain at six months. A higher pre-weight-loss plasma concentration of unacylated ghrelin is a modest predictor of weight loss success in males and females, while a higher leptin:ghrelin ratio is a predictor of weight loss failure in females. Further investigation is required into what combinations and concentrations of these hormones are optimal for weight loss success. PMID:26921488

  9. Design and performance of a spin-polarized electron energy loss spectrometer with high momentum resolution.

    PubMed

    Vasilyev, D; Kirschner, J

    2016-08-01

    We describe a new "complete" spin-polarized electron energy loss spectrometer comprising a spin-polarized primary electron source, an imaging electron analyzer, and a spin analyzer of the "spin-polarizing mirror" type. Unlike previous instruments, we have a high momentum resolution of less than 0.04 Å(-1), at an energy resolution of 90-130 meV. Unlike all previous studies which reported rather broad featureless data in both energy and angle dependence, we find richly structured spectra depending sensitively on small changes of the primary energy, the kinetic energy after scattering, and of the angle of incidence. The key factor is the momentum resolution. PMID:27587131

  10. Energy loss of MeV protons specularly reflected from metal surfaces

    SciTech Connect

    Juaristi, J.I.

    1996-05-01

    A parameter-free model is presented to study the energy loss of fast protons specularly reflected from metal surfaces. The contributions to the energy loss from excitation of valence-band electrons and ionization of localized target-atom electronic states are calculated separately. The former is calculated from the induced surface wake potential using linear response theory and the specular-reflection model, while the latter is calculated in the first Born approximation. The results obtained are in good agreement with available experimental data. However, the experimental qualitative trend of the energy loss as a function of the angle of incidence is obtained when the valence-band electron model is replaced by localized target atom electron states, though with a worse quantitative agreement. {copyright} {ital 1996 The American Physical Society.}

  11. Additive effects of electronic and nuclear energy losses in irradiation-induced amorphization of zircon

    SciTech Connect

    Zarkadoula, Eva; Toulemonde, Marcel; Weber, William J.

    2015-12-28

    We used a combination of ion cascades and the unified thermal spike model to study the electronic effects from 800 keV Kr and Xe ion irradiation in zircon. We compared the damage production for four cases: (a) due to ion cascades alone, (b) due to ion cascades with the electronic energy loss activated as a friction term, (c) due to the thermal spike from the combined electronic and nuclear energy losses, and (d) due to ion cascades with electronic stopping and the electron-phonon interactions superimposed. We found that taking the electronic energy loss out as a friction term results in reduced damage, while the electronic electron-phonon interactions have additive impact on the final damage created per ion.

  12. Additive effects of electronic and nuclear energy loss in irradiation-induced amorphization of zircon

    SciTech Connect

    Zarkadoula, Eva; Toulemonde, Marcel; Weber, William J.

    2015-12-29

    We used a combination of ion cascades and the unified thermal spike model to study the electronic effects from 800 keV Kr and Xe ion irradiation in zircon. We compared the damage production for four cases: (a) due to ion cascades alone, (b) due to ion cascades with the electronic energy loss activated as a friction term, (c) due to the thermal spike from the combined electronic and nuclear energy losses, and (d) due to ion cascades with electronic stopping and the electron-phonon interactions superimposed. As a result, we found that taking the electronic energy loss out as a friction term results in reduced damage, while the electronic electron-phonon interactions have additive impact on the final damage created per ion.

  13. Additive effects of electronic and nuclear energy loss in irradiation-induced amorphization of zircon

    DOE PAGESBeta

    Zarkadoula, Eva; Toulemonde, Marcel; Weber, William J.

    2015-12-29

    We used a combination of ion cascades and the unified thermal spike model to study the electronic effects from 800 keV Kr and Xe ion irradiation in zircon. We compared the damage production for four cases: (a) due to ion cascades alone, (b) due to ion cascades with the electronic energy loss activated as a friction term, (c) due to the thermal spike from the combined electronic and nuclear energy losses, and (d) due to ion cascades with electronic stopping and the electron-phonon interactions superimposed. As a result, we found that taking the electronic energy loss out as a frictionmore » term results in reduced damage, while the electronic electron-phonon interactions have additive impact on the final damage created per ion.« less

  14. Energy loss of ions at metal surfaces: Band-structure effects

    SciTech Connect

    Alducin, M.; Silkin, V.M.; Juaristi, J.I.; Chulkov, E.V.

    2003-03-01

    We study band-structure effects on the energy loss of protons scattered off the Cu (111) surface. The distance dependent stopping power for a projectile traveling parallel to the surface is calculated within the linear response theory. The self-consistent electronic response of the system is evaluated within the random-phase approximation. In order to characterize the surface band structure, the electronic single-particle wave functions and energies are obtained by solving the Schroedinger equation with a realistic one-dimensional model potential. This potential reproduces the main features of the Cu (111) surface: the energy band gap for electron motion along the surface normal, as well as the binding energy of the occupied surface state and the first image state. Comparison of our results with those obtained within the jellium model allows us to characterize the band-structure effects in the energy loss of protons interacting with the Cu (111) surface.

  15. Heavy quark energy loss in high multiplicity proton-proton collisions at the LHC.

    PubMed

    Vogel, Sascha; Gossiaux, Pol Bernard; Werner, Klaus; Aichelin, Jörg

    2011-07-15

    One of the most promising probes to study deconfined matter created in high energy nuclear collisions is the energy loss of (heavy) quarks. It has been shown in experiments at the Relativistic Heavy Ion Collider that even charm and bottom quarks, despite their high mass, experience a remarkable medium suppression in the quark gluon plasma. In this exploratory investigation we study the energy loss of heavy quarks in high multiplicity proton-proton collisions at LHC energies. Although the colliding systems are smaller than compared to those at the Relativistic Heavy Ion Collider (p+p vs Au+Au), the higher energy might lead to multiplicities comparable to Cu+Cu collisions at the Relativistic Heavy Ion Collider. The interaction of charm quarks with this environment gives rise to a non-negligible suppression of high momentum heavy quarks in elementary collisions. PMID:21838351

  16. Quantitative analysis of electron energy loss spectra and modelling of optical properties of multilayer systems for extreme ultraviolet radiation regime

    SciTech Connect

    Gusenleitner, S.; Hauschild, D.; Reinert, F.; Handick, E.

    2014-03-28

    Ruthenium capped multilayer coatings for use in the extreme ultraviolet (EUV) radiation regime have manifold applications in science and industry. Although the Ru cap shall protect the reflecting multilayers, the surface of the heterostructures suffers from contamination issues and surface degradation. In order to get a better understanding of the effects of these impurities on the optical parameters, reflection electron energy loss spectroscopy (REELS) measurements of contaminated and H cleaned Ru multilayer coatings were taken at various primary electron beam energies. Experiments conducted at low primary beam energies between 100 eV and 1000 eV are very surface sensitive due to the short inelastic mean free path of the electrons in this energy range. Therefore, influences of the surface condition on the above mentioned characteristics can be appraised. In this paper, it can be shown that carbon and oxide impurities on the mirror surface decrease the transmission of the Ru cap by about 0.75% and the overall reflectance of the device is impaired as the main share of the non-transmitted EUV light is absorbed in the contamination layer.

  17. Non-Linear Approach to the Energy Loss of Ions in Solids

    NASA Astrophysics Data System (ADS)

    Arista, Néstor R.; Lifschitz, Agustín F.

    The present work includes the discussion of three main aspects in the area of the energy loss of ions in solids. First we review some of the main features contained in the historical Bohr, Bethe and Bloch theories, and related models based on them. Then we analyze new developments in this area based on a non-linear formulation of the energy loss of ions in a free electron gas. As a final question, we reconsider, from the new perspective of the non-linear approach, some long-standing problems concerning the charge state of ions moving in solids and its relationship with the effective charge concept.

  18. Charm quark energy loss in infinite QCD matter using a parton cascade model

    NASA Astrophysics Data System (ADS)

    Younus, Mohammed; Coleman-Smith, Christopher E.; Bass, Steffen A.; Srivastava, Dinesh K.

    2015-02-01

    We utilize the parton cascade model to study the evolution of charm quarks propagating through a thermal brick of QCD matter. We determine the energy loss and the transport coefficient q ̂ for charm quarks. The calculations are done at a constant temperature of 350 MeV and the results are compared to analytical calculations of heavy-quark energy loss in order to validate the applicability of using a parton cascade model for the study of heavy-quark dynamics in hot and dense QCD matter.

  19. Non-equilibrium energy loss for very highly charged ions in insulators

    SciTech Connect

    Briere, M.A.; Schenkel, T.; Bauer, P.; Amau, A.

    1996-12-31

    The energy loss of 144 keV Ar{sup +16} ions on a bilayer structure of C-CaF{sub 2} has been measured. An asymmetry in the results is found depending on which layer is passed by the ion first: the energy loss is about four times larger when the CaF{sub 2} layer is traversed by the ion first. We interpret this as an indication of the existence of a nonequilibrium charge state of the Ar ions inside the solid in the case of the insulator.

  20. Neutrino Energy Loss Rates due to {sup 54,55,56}Fe in Stellar Environment

    SciTech Connect

    Nabi, Jameel-Un

    2010-06-01

    Neutrino energy loss rates are required as a key nuclear physics input parameter in the simulation codes of core-collapse supernovae of massive stars. The weak interaction rates due to isotopes of iron, {sup 54,55,56}Fe, are considered to play an important role during the presupernova evolution of massive stars. Proton-neutron quasi-particle random phase approximation (pn-QRPA) theory has recently being used for a microscopic calculation of stellar weak interaction rates of iron isotopes with success. The calculation of neutrino energy loss rates due to {sup 54,55,56}Fe is presented along with a comparison with large scale shell model results.

  1. The energy loss straggling of low Z ions in solids and gases

    NASA Astrophysics Data System (ADS)

    Montanari, C. C.; Miraglia, J. E.

    2013-04-01

    We present a study on the energy loss straggling of low Z ions (H up to B) in different solid (Al, Ti, Cu, Zn, Ge, Au) and gaseous targets (Ne, Ar, Kr, Xe). This work includes on one side, a critical analysis of the available experimental data and possible non-statistical (rugosity and inhomogeneity) contributions. On the other side, theoretical calculations performed by using the shell-wise local plasma approximation and the comparison of these results with the experimental data and with other theoretical curves available in the literature. We find that for the ions here considered, the square of the energy loss straggling normalized to Bohr limit is independent of the ion nuclear charge and of the ion charge state, in the case of electrons bound to the projectile. This shows a clear Z2 dependence of the square energy loss straggling, with Z being the ion nuclear charge. The tendency to Bohr limit at high energies, and the inconvenience of using Yang formula (Q. Yang etal, Nucl. Instrum. Meth. Phys. Res B 61, 149-155 (1991)) are also mentioned. The bases for the future development of a general formula for the energy loss straggling are introduced.

  2. Imaging of metallic nano-particles using plasmon/valence energy loss electrons

    SciTech Connect

    Hunt, E.M.; Wang, Z.L.; Hampikian, J.M.; Evans, N.D.

    1997-04-01

    Although crystal lattices can be determined reasonably well using high-resolution electron microscopy, determination of local chemistry at high spatial-resolution remains a challenge. An energy-filtering system has made it possible to perform chemically sensitive imaging in a transmission electron microscopy (TEM). This type of imaging usually relies on the signal of the inner shell ionization edge, the intensity of which is affected by the threshold energy-loss and the ionization cross-section of the edge. Therefore, the spatial resolution of a core loss image is strongly affected by the signal-to-noise ratio. In this respect, lower loss electrons from the plasmon or valence region of the energy loss spectrum (10--100 eV) are favorable for chemically sensitive imaging due to the much higher signal intensity, provided any delocalization effects are small in comparison to the required spatial resolution. Compositionally sensitive imaging using the aluminum plasmon energy-loss electrons has been shown to produce {approximately}2nm resolution for an atomically sharp Al/Ti interface. Using this resolution result the reason for the compositional contrast seen in an ion implanted specimen is postulated. The sputter deposited Al/Ti polycrystalline multilayer specimen was imaged using a JEOL 3010 TEM at 300 kV equipped with a Gatan Imaging Filter (GIF{trademark}). The implanted alumina sample was imaged with a GIF{trademark} interfaced to a Philips CM30 TEM operated at 300 keV. The low-loss images were gain normalized, 512 x 512 pixels in size and were recorded with an exposure time of 1 second and an energy-selecting window of 5 eV.

  3. Intermittent Moderate Energy Restriction Improves Weight Loss Efficiency in Diet-Induced Obese Mice

    PubMed Central

    Seimon, Radhika V.; Shi, Yan-Chuan; Slack, Katy; Lee, Kailun; Fernando, Hamish A.; Nguyen, Amy D.; Zhang, Lei; Lin, Shu; Enriquez, Ronaldo F.; Lau, Jackie

    2016-01-01

    Background Intermittent severe energy restriction is popular for weight management. To investigate whether intermittent moderate energy restriction may improve this approach by enhancing weight loss efficiency, we conducted a study in mice, where energy intake can be controlled. Methods Male C57/Bl6 mice that had been rendered obese by an ad libitum diet high in fat and sugar for 22 weeks were then fed one of two energy-restricted normal chow diets for a 12-week weight loss phase. The continuous diet (CD) provided 82% of the energy intake of age-matched ad libitum chow-fed controls. The intermittent diet (ID) provided cycles of 82% of control intake for 5–6 consecutive days, and ad libitum intake for 1–3 days. Weight loss efficiency during this phase was calculated as (total weight change) ÷ [(total energy intake of mice on CD or ID)–(total average energy intake of controls)]. Subsets of mice then underwent a 3-week weight regain phase involving ad libitum re-feeding. Results Mice on the ID showed transient hyperphagia relative to controls during each 1–3-day ad libitum feeding period, and overall ate significantly more than CD mice (91.1±1.0 versus 82.2±0.5% of control intake respectively, n = 10, P<0.05). There were no significant differences between CD and ID groups at the end of the weight loss or weight regain phases with respect to body weight, fat mass, circulating glucose or insulin concentrations, or the insulin resistance index. Weight loss efficiency was significantly greater with ID than with CD (0.042±0.007 versus 0.018±0.001 g/kJ, n = 10, P<0.01). Mice on the CD exhibited significantly greater hypothalamic mRNA expression of proopiomelanocortin (POMC) relative to ID and control mice, with no differences in neuropeptide Y or agouti-related peptide mRNA expression between energy-restricted groups. Conclusion Intermittent moderate energy restriction may offer an advantage over continuous moderate energy restriction, because it induces

  4. Energy-loss of He ions in carbon allotropes studied by elastic resonance in backscattering spectra

    NASA Astrophysics Data System (ADS)

    Tosaki, Mitsuo; Rauhala, Eero

    2015-10-01

    Backscattering spectra for 4He ions incident on carbon allotropes have been measured in the energy range from 4.30 to 4.95 MeV in steps of 50-100 keV at scattering angles of 106° and 170°. We used three carbon allotropes: graphite, diamond and amorphous carbon. For all these allotropes, we can observe the sharp (4He, 12C) elastic nuclear resonance at the He ion energy of 4.265 MeV in the backscattering spectra. By varying the incident He energy, we have systematically analyzed the profiles of the resonance peaks to study the energy-loss processes: stopping cross-sections and energy-loss straggling around the interesting region of the stopping maximum at about 500 keV. We focus on the resonance profiles and investigate an allotropic effect concerning the energy-loss. Furthermore, an energy bunching effect on the straggling is presented and the mechanism is discussed.

  5. Fast-ion Energy Loss During TAE Avalanches in the National Spherical Torus Experiment

    SciTech Connect

    Fredrickson, E D; Darrow, D S; Gorelenkov, N N; Kramer, G J; Kubota, S; Podesta, M; White, R B; Bortolon, A; Gerhardt, S P; Bell, R E; Diallo, A; LeBlanc, B; Levinton, F M

    2012-07-11

    Strong TAE avalanches on NSTX, the National Spherical Torus Experiment [M. Ono, et al., Nucl. Fusion 40 (2000) 557] are typically correlated with drops in the neutron rate in the range of 5% - 15%. In previous studies of avalanches in L-mode plasmas, these neutron drops were found to be consistent with modeled losses of fast ions. Here we expand the study to TAE avalanches in NSTX H-mode plasmas with improved analysis techniques. At the measured TAE mode amplitudes, simulations with the ORBIT code predict that fast ion losses are negligible. However, the simulations predict that the TAE scatter the fast ions in energy, resulting in a small (≈ 6%) drop in fast ion β. The net decrease in energy of the fast ions is sufficient to account for the bulk of the drop in neutron rate, even in the absence of fast ion losses. This loss of energy from the fast ion population is comparable to the estimated energy lost by damping from the Alfven wave during the burst. The previously studied TAE avalanches in L-mode are re-evaluated using an improved calculation of the potential fluctuations in the ORBIT code.

  6. Surface and bulk-loss reduction research by low-energy hydrogen doping

    NASA Technical Reports Server (NTRS)

    Fonash, S.

    1985-01-01

    Surface and bulk loss reduction by low energy hydrogen doping of silicon solar cells was examined. Hydrogen ions provided a suppression of space charge recombination currents. Implantation of hydrogen followed by the anneal cycle caused more redistribution of boron than the anneal which could complicate processing. It was demonstrated that passivation leads to space charge current reduction.

  7. Model for Calculating Electrolytic Shunt Path Losses in Large Electrochemical Energy Conversion Systems

    NASA Technical Reports Server (NTRS)

    Prokopius, P. R.

    1976-01-01

    Generalized analysis and solution techniques were developed to evaluate the shunt power losses in electrochemical systems designed with a common or circulating electrolyte supply. Sample data are presented for a hypothetical bulk energy storage redox system, and the general applicability of the analysis technique is discussed.

  8. Energy loss and dynamical evolution of quark p{sub T} spectra

    SciTech Connect

    Roy, Pradip; Dutt-Mazumder, Abhee K.

    2006-04-15

    Average energy loss of light quarks has been calculated in a two stage equilibrium scenario where the quarks are executing Brownian motion in a gluonic heat bath. The evolution of the quark p{sub T} spectra is studied by solving Fokker-Planck equation in an expanding plasma. Results are finally compared with experimentally measured pion p{sub T} spectrum at RHIC.

  9. Loss of energy dissipation capacity from the deadzone in linear and nonlinear viscous damping devices

    NASA Astrophysics Data System (ADS)

    Tong, Mai; Liebner, Thomas

    2007-03-01

    In a viscous damping device under cyclic loading, after the piston reaches a peak stroke, the reserve movement that follows may sometimes experience a short period of delayed or significantly reduced device force output. A similar delay or reduced device force output may also occur at the damper’s initial stroke as it moves away from its neutral position. This phenomenon is referred to as the effect of “deadzone”. The deadzone can cause a loss of energy dissipation capacity and less efficient vibration control. It is prominent in small amplitude vibrations. Although there are many potential causes of deadzone such as environmental factors, construction, material aging, and manufacture quality, in this paper, its general effect in linear and nonlinear viscous damping devices is analyzed. Based on classical dynamics and damping theory, a simple model is developed to capture the effect of deadzone in terms of the loss of energy dissipation capacity. The model provides several methods to estimate the loss of energy dissipation within the deadzone in linear and sublinear viscous fluid dampers. An empirical equation of loss of energy dissipation capacity versus deadzone size is formulated, and the equivalent reduction of effective damping in SDOF systems has been obtained. A laboratory experimental evaluation is carried out to verify the effect of deadzone and its numerical approximation. Based on the analysis, a modification is suggested to the corresponding formulas in FEMA 356 for calculation of equivalent damping if a deadzone is to be considered.

  10. Electron beam guiding by grooved SiO2 parallel plates without energy loss

    NASA Astrophysics Data System (ADS)

    Xue, Yingli; Yu, Deyang; Liu, Junliang; Zhang, Mingwu; Yang, Bian; Zhang, Yuezhao; Cai, Xiaohong

    2015-12-01

    Using a pair of grooved SiO2 parallel plates, stably guided electron beams were obtained without energy loss at 800-2000 eV. This shows that the transmitted electrons are guided by a self-organized repulsive electric field, paving the way for a self-adaptive manipulation of electron beams.

  11. Electron beam guiding by grooved SiO{sub 2} parallel plates without energy loss

    SciTech Connect

    Xue, Yingli; Yu, Deyang Liu, Junliang; Zhang, Mingwu; Yang, Bian; Zhang, Yuezhao; Cai, Xiaohong

    2015-12-21

    Using a pair of grooved SiO{sub 2} parallel plates, stably guided electron beams were obtained without energy loss at 800–2000 eV. This shows that the transmitted electrons are guided by a self-organized repulsive electric field, paving the way for a self-adaptive manipulation of electron beams.

  12. Polarization correction in the theory of energy losses by charged particles

    SciTech Connect

    Makarov, D. N. Matveev, V. I.

    2015-05-15

    A method for finding the polarization (Barkas) correction in the theory of energy losses by charged particles in collisions with multielectron atoms is proposed. The Barkas correction is presented in a simple analytical form. We make comparisons with experimental data and show that applying the Barkas correction improves the agreement between theory and experiment.

  13. Measurement of Absolute Excitation Cross Sections in Highly-Charged Ions Using Electron Energy Loss and Merged Beams

    NASA Technical Reports Server (NTRS)

    Chutjian, A.; Smith, Steven J.; Lozano, J.

    2002-01-01

    There is increasing emphasis during this decade on understanding energy balance and phenomena observed in high electron temperature plasmas. The UV spectral return from FUSE, the X-ray spectral return from the HETG on Chandra and the LETGS 011 XMM-Newton are just beginning. Line emissions are almost entirely from highly-charged ions (HCIs) of C, N, 0, Ne, Mg, S, Si, Ca, and Fe. The Constellation-X mission will provide X-ray spectroscopy up to photon energies of 0.12 nm (10 keV) where primary line emitters will be HCIs. A variety of atomic parameters are required to model the stellar and solar plasma. These include cross sections for excitation, ionization, charge-exchange, X-ray emission, direct and indirect recombination, lifetimes and branching ratios, and dependences on l, m mixing by external E and B fields. In almost all cases the atomic quantities are calculated, and few comparisons to experiment have been carried out. Collision strengths and Einstein A-values are required to convert the observed spectral intensities to electron temperatures and densities in the stellar plasma. The JPL electron energy-loss and merged beam approach has been used to measure absolute collision strengths in a number of ions, with critical comparison made to the best available theories.

  14. Competing Effects Of Electronic And Nuclear Energy Loss On Microstructural Evolution In Ionic-covalent Materials

    SciTech Connect

    Zhang, Yanwen; Varga, Tamas; Ishimaru, Manabu; Edmondson, P. D.; Xue, H.; Liu, Peng; Moll, Sandra; Hardiman, Christopher M.; Shannon, Steven; Weber, William J.

    2014-05-01

    Ever increasing energy needs have raised the demands for advanced fuels and cladding materials that withstand the extreme radiation environments with improved accident tolerance over a long period of time. Ceria (CeO2) is a well known ionic conductor that is isostructural with urania and plutonia-based nuclear fuels. In the context of nuclear fuels, immobilization and transmutation of actinides, CeO2 is a model system for radiation effect studies. Covalent silicon carbide (SiC) is a candidate for use as structural material in fusion, cladding material for fission reactors, and an inert matrix for the transmutation of plutonium and other radioactive actinides. Understanding microstructural change of these ionic-covalent materials to irradiation is important for advanced nuclear energy systems. While displacements from nuclear energy loss may be the primary contribution to damage accumulation in a crystalline matrix and a driving force for the grain boundary evolution in nanostructured materials, local non-equilibrium disorder and excitation through electronic While displacements from nuclear energy loss may be the primary contribution to damage accumulation in a crystalline matrix and a driving force for the grain boundary evolution in nanostructured materials, local non-equilibrium disorder and excitation through electronic energy loss may, however, produce additional damage or anneal pre-existing defect. At intermediate transit energies where electronic and nuclear energy losses are both significant, synergistic, additive or competitive processes may evolve that affect the dynamic response of materials to irradiation. The response of crystalline and nanostructured CeO2 and SiC to ion irradiation are studied under different nuclear and electronic stopping powers to describe some general material response in this transit energy regime. Although fast radiation-induced grain growth in CeO2 is evident with no phase transformation, different fluence and dose dependence

  15. Quadratic energy-loss straggling and energy widths of the states of slow ions in an electron gas

    SciTech Connect

    Wang, N.

    1997-10-01

    The energy-loss straggling and energy width of states of slow ions interacting with a homogeneous electron gas are evaluated within a quadratic response theory and the random-phase approximation. These results are compared with corresponding results determined from a fully nonlinear scattering theory approach. The quadratic response theory is shown to be a good approximation for high electron densities and small ion charges. {copyright} {ital 1997} {ital The American Physical Society}

  16. Radiation and ionization energy loss simulation for the GDH sum rule experiment in Hall-A at Jefferson Lab

    DOE PAGESBeta

    Yan, Xin -Hu; Ye, Yun -Xiu; Chen, Jian -Ping; Lu, Hai -Jiang; Zhu, Peng -Jia; Jiang, Feng -Jian

    2015-07-17

    The radiation and ionization energy loss are presented for single arm Monte Carlo simulation for the GDH sum rule experiment in Hall-A at Jefferson Lab. Radiation and ionization energy loss are discussed formore » $$^{12}C$$ elastic scattering simulation. The relative momentum ratio $$\\frac{\\Delta p}{p}$$ and $$^{12}C$$ elastic cross section are compared without and with radiation energy loss and a reasonable shape is obtained by the simulation. The total energy loss distribution is obtained, showing a Landau shape for $$^{12}C$$ elastic scattering. This simulation work will give good support for radiation correction analysis of the GDH sum rule experiment.« less

  17. Radiation and ionization energy loss simulation for the GDH sum rule experiment in Hall-A at Jefferson Lab

    SciTech Connect

    Yan, Xin -Hu; Ye, Yun -Xiu; Chen, Jian -Ping; Lu, Hai -Jiang; Zhu, Peng -Jia; Jiang, Feng -Jian

    2015-07-17

    The radiation and ionization energy loss are presented for single arm Monte Carlo simulation for the GDH sum rule experiment in Hall-A at Jefferson Lab. Radiation and ionization energy loss are discussed for $^{12}C$ elastic scattering simulation. The relative momentum ratio $\\frac{\\Delta p}{p}$ and $^{12}C$ elastic cross section are compared without and with radiation energy loss and a reasonable shape is obtained by the simulation. The total energy loss distribution is obtained, showing a Landau shape for $^{12}C$ elastic scattering. This simulation work will give good support for radiation correction analysis of the GDH sum rule experiment.

  18. Exact Analytical Solutions of Continuity Equation for Electron Beams Precipitating in Ohmic and Mixed Energy Losses

    NASA Astrophysics Data System (ADS)

    Dobranskis, Rytis; Zharkova, Valentina

    2015-04-01

    In this paper we extend the approach presented in Dobranskis & Zharkova (2014a,b) by updating the analytical solutions of continuity equation (CE) for pure Ohmic losses and developing a method for analytical solutions to account simultaneously for both collisional and Ohmic losses. The exact solutions of CE for electron density of the beams precipitating in Ohmic losses are found at different precipitation depths for precipitating and "returning") electrons. Then the iterative process was applied to calculate the differential density for mixed (Ohmic and collisional) energy losses (MEL). The differential densities obtained from the updated CE for Coulomb collisions and MEL are used to calculate the HXR intensity for relativistic cross-section and to compare the outcome with more accurate results found from the numerical Fokker-Planck (FP) solution for the same collisional and Ohmic losses. The HXR intensity distribution produced by MEL solution reveals a close resemblance to the results from the numerical FP solution, being almost identical for weaker soft electron beams. However, the MEL simulation can be run up to 30 times faster than the numerical FP. This method implemented in IDL is to be incorporated into the RHESSI software that can be used for quick estimation of the effect of Ohmic losses versus collisions from the RHESSI data.

  19. In-source resonance ionization spectroscopy of high lying energy levels in atomic uranium

    NASA Astrophysics Data System (ADS)

    Raeder, Sebastian; Fies, Silke; Gottwald, Tina; Mattolat, Christoph; Rothe, Sebastian; Wendt, Klaus

    2010-02-01

    In-source resonance ionization spectroscopy of uranium has been carried out as preparation for the analysis of low contaminations of nuclear material in environmental samples via laser mass spectrometry. Using three-step resonance ionization spectroscopy, 86 levels of odd parity in the energy range from 37,200-38,650 cm - 1 were studied, 51 of these levels were previously unknown. Suitable excitation schemes for analytic applications are discussed.

  20. Timescale and magnitude of plasma thermal energy loss before and during disruptions in JET

    NASA Astrophysics Data System (ADS)

    Riccardo, V.; Loarte, A.; JET EFDA Contributors

    2005-11-01

    In this paper we analyse and discuss the thermal energy loss dynamics before and during JET disruptions that occurred between 2002 and 2004 in discharges which reached >4.5 MJ of thermal energy. We observe the slow thermal energy transients with diamagnetic loops and the fast ones with electron cyclotron emission and soft x-ray diagnostics. For most disruption types in JET, the plasma thermal energy at the time of the thermal quench is substantially less than that of the full performance plasma, typically in the range of 10-50% depending on plasma conditions and disruption type. The exceptions to this observation are disruptions in plasmas with a strong internal transport barrier (ITB) and in discharges terminating in a pure vertical displacement event, in which the plasma conserves a very high energy content up to the thermal quench. These disruption types are very sudden, leaving little scope for the combined action of soft plasma landing strategies and intrinsic performance degradation, both requiring >500 ms to be effective, to decrease the available thermal energy. The characteristic time for the loss of energy from the main plasma towards the PFCs in the thermal quench of JET disruptions is in the range 0.05-3.0 ms. The shortest timescales are typical of disruptions caused by excessive pressure peaking in ITB discharges. The available thermal energy fraction and thermal quench duration observed in JET can be processed (with due caution) into estimates for the projected PFC lifetime of the ITER target.

  1. IMPLICATIONS OF MASS AND ENERGY LOSS DUE TO CORONAL MASS EJECTIONS ON MAGNETICALLY ACTIVE STARS

    SciTech Connect

    Drake, Jeremy J.; Cohen, Ofer; Yashiro, Seiji; Gopalswamy, Nat

    2013-02-20

    Analysis of a database of solar coronal mass ejections (CMEs) and associated flares over the period 1996-2007 finds well-behaved power-law relationships between the 1-8 A flare X-ray fluence and CME mass and kinetic energy. We extrapolate these relationships to lower and higher flare energies to estimate the mass and energy loss due to CMEs from stellar coronae, assuming that the observed X-ray emission of the latter is dominated by flares with a frequency as a function of energy dn/dE = kE {sup -{alpha}}. For solar-like stars at saturated levels of X-ray activity, the implied losses depend fairly weakly on the assumed value of {alpha} and are very large: M-dot {approx}5 Multiplication-Sign 10{sup -10} M{sub sun} yr{sup -1} and E-dot {approx}0.1 L{sub sun}. In order to avoid such large energy requirements, either the relationships between CME mass and speed and flare energy must flatten for X-ray fluence {approx}> 10{sup 31} erg, or the flare-CME association must drop significantly below 1 for more energetic events. If active coronae are dominated by flares, then the total coronal energy budget is likely to be up to an order of magnitude larger than the canonical 10{sup -3} L {sub bol} X-ray saturation threshold. This raises the question of what is the maximum energy a magnetic dynamo can extract from a star? For an energy budget of 1% of L {sub bol}, the CME mass loss rate is about 5 Multiplication-Sign 10{sup -11} M {sub Sun} yr{sup -1}.

  2. A Computational Study of Energy Efficiency and Pressure Losses in the Total Cavopulmonary Connection

    NASA Astrophysics Data System (ADS)

    Marsden, Alison

    2005-11-01

    The total cavopulmonary connection (TCPC) is an operation performed to treat single ventricle congenital heart defects. The superior and inferior vena cavae are connected to the pulmonary arteries in a t-shaped junction, separating the systemic and pulmonary circulations. In this work, we hypothesize that the effects of respiration and exercise cause significant hemodynamic disturbances and energy loss. Time- dependent, 3-D blood flow simulations are performed using a custom finite element solver and patient specific geometry. Blood flow features, pressure, and energy losses are analyzed at rest and with increasing flow rates to simulate exercise conditions. Resistance boundary conditions are enforced at the pulmonary artery outlets. Energy efficiency is high at rest but drops substantially with maximal exercise. Flow vortices increase in intensity with respiration and exercise, explaining higher energy dissipation when compared to rest. Pressure drop and energy loss in the TCPC are small at rest but increase to significant levels, even at moderate exercise. We conclude that the effects of respiration and exercise should be incorporated in models to provide realistic evaluations of TCPC performance, and for future work in optimizing TCPC geometry.

  3. Study of the radiated energy loss during massive gas injection mitigated disruptions on EAST

    NASA Astrophysics Data System (ADS)

    Duan, Y. M.; Hao, Z. K.; Hu, L. Q.; Wang, L.; Xu, P.; Xu, L. Q.; Zhuang, H. D.

    2015-08-01

    The MGI mitigated disruption experiments were carried out on EAST with a new fast gas controlling valve in 2012. Different amounts of noble gas He or mixed gas of 99% He + 1% Ar are injected into plasma in current flat-top phase and current ramp-down phase separately. The initial results of MGI experiments are described. The MGI system and the radiation measurement system are briefly introduced. The characteristics of radiation distribution and radiation energy loss are analyzed. About 50% of the stored thermal energy Wdia is dissipated by radiation during the entire disruption process and the impurities of C and Li from the PFC play important roles to radiative energy loss. The amount of the gas can affect the pre-TQ phase. Strong poloidal asymmetry of radiation begins to appear in the CQ phase, which is possibly caused by the plasma configuration changes as a result of VDE. No toroidal radiation asymmetry is observed presently.

  4. Energy losses of nanomechanical resonators induced by atomic force microscopy-controlled mechanical impedance mismatching

    PubMed Central

    Rieger, Johannes; Isacsson, Andreas; Seitner, Maximilian J.; Kotthaus, Jörg P.; Weig, Eva M.

    2014-01-01

    Clamping losses are a widely discussed damping mechanism in nanoelectromechanical systems, limiting the performance of these devices. Here we present a method to investigate this dissipation channel. Using an atomic force microscope tip as a local perturbation in the clamping region of a nanoelectromechanical resonator, we increase the energy loss of its flexural modes by at least one order of magnitude. We explain this by a transfer of vibrational energy into the cantilever, which is theoretically described by a reduced mechanical impedance mismatch between the resonator and its environment. A theoretical model for this mismatch, in conjunction with finite element simulations of the evanescent strain field of the mechanical modes in the clamping region, allows us to quantitatively analyse data on position and force dependence of the tip-induced damping. Our experiments yield insights into the damping of nanoelectromechanical systems with the prospect of engineering the energy exchange in resonator networks. PMID:24594876

  5. Multilayered perceptron neural networks to compute energy losses in magnetic cores

    NASA Astrophysics Data System (ADS)

    Kucuk, Ilker

    2006-12-01

    This paper presents a new approach based on multilayered perceptrons (MLPs) to compute the specific energy losses of toroidal wound cores built from 3% SiFe 0.27 mm thick M4, 0.1 and 0.08 mm thin gauge electrical steel strips. The MLP has been trained by a back-propagation and extended delta-bar-delta learning algorithm. The results obtained by using the MLP model were compared with a commonly used conventional method. The comparison has shown that the proposed model improved loss estimation with respect to the conventional method.

  6. Charge-state-dependent energy loss of slow ions. I. Experimental results on the transmission of highly charged ions

    NASA Astrophysics Data System (ADS)

    Wilhelm, Richard A.; Gruber, Elisabeth; Smejkal, Valerie; Facsko, Stefan; Aumayr, Friedrich

    2016-05-01

    We report on energy loss measurements of slow (v ≪v0 ), highly charged (Q >10 ) ions upon transmission through a 1-nm-thick carbon nanomembrane. We emphasize here the scaling of the energy loss with the velocity and charge exchange or loss. We show that a weak linear velocity dependence exists, whereas charge exchange dominates the kinetic energy loss, especially in the case of a large charge capture. A universal scaling of the energy loss with the charge exchange and velocity is found and discussed in this paper. A model for charge-state-dependent energy loss for slow ions is presented in paper II in this series [R. A. Wilhelm and W. Möller, Phys. Rev. A 93, 052709 (2016), 10.1103/PhysRevA.93.052709].

  7. Energy losses of fast heavy multiply charged structural ions in collisions with complex atoms

    NASA Astrophysics Data System (ADS)

    Matveev, V. I.; Sidorov, D. B.

    2007-07-01

    A nonperturbatve theory of energy losses of fast heavy multiply charged structural ions in collisions with neutral complex atoms is elaborated with allowance for simultaneous excitations of ionic and atomic electron shells. Formulas for the effective deceleration that are similar to the well-known Bethe-Bloch formulas are derived. By way of example, the energy lost by partially stripped U q+ ions (10 ≤ q ≤ 70) colliding with argon atoms and also the energy lost by Au, Pb, and Bi ions colliding with various targets are calculated. The results of calculation are compared with experimental data.

  8. Charge deposition dependence and energy loss of electrons transmitted through insulating PET nanocapillaries

    NASA Astrophysics Data System (ADS)

    Keerthisinghe, D.; Dassanayake, B. S.; Wickramarachchi, S. J.; Stolterfoht, N.; Tanis, J. A.

    2013-12-01

    The charge deposition dependence and energy loss in the transmission of electrons through insulating polyethylene terephthalate (PET) were studied for incident energies of 500 and 800 eV. Charge evolution at the sample tilt angles ψ = 0.0° and -1.7° was investigated. After an initial quiescent period transmission was observed and found to reach equilibrium rather quickly. Inelastic behavior of the transmitted electrons was observed during the initial transmission as well as after reaching equilibrium for ψ = -1.7° for both incident energies.

  9. Energy-loss and straggling of hydrogen and helium ions in selenium

    NASA Astrophysics Data System (ADS)

    Conradie, J.; Lombaard, J.; Friedland, E.

    1983-01-01

    Using a transmission technique, the energy-loss and straggling of protons, deuterons and helium ions in Se were measured in the energy range between 0.3 and 2.5 MeV. The experimental stopping powers of the various ions are the same as the semiempirical values of Andersen and Ziegler, except in the vicinity of the stopping power maximum. The reduced straggling for the helium and hydrogen ions is energy independent above 0.25 MeV/amu with the helium values the same as predicted by Bohr but the hydrogen values are somewhat lower.

  10. Monochromated, spatially resolved electron energy-loss spectroscopic measurements of gold nanoparticles in the plasmon range.

    PubMed

    Schaffer, B; Riegler, K; Kothleitner, G; Grogger, W; Hofer, F

    2009-02-01

    Gold nanoparticles show optical properties different from bulk material due to resonance phenomena which depend on local structure and geometry. Electron energy-loss spectrometry (EELS) in scanning transmission electron microscopy (STEM) allows the spatially resolved measurement of these properties at a resolution of few nanometers. In this work, the first monochromated measurements of gold nanoparticles (spheres, rods and triangles) are presented. Due to the improved energy resolution of about 0.2 eV, surface plasmon excitations at energies below 1 eV could be accurately measured from raw experimental data. PMID:18722779

  11. Updated analytical solutions of continuity equation for electron beams precipitation - II. Mixed energy losses

    NASA Astrophysics Data System (ADS)

    Zharkova, V. V.; Dobranskis, R. R.

    2016-06-01

    In this paper we consider simultaneous analytical solutions of continuity equations for electron beam precipitation (a) in collisional losses and (b) in ohmic losses, or mixed energy losses (MEL) by applying the iterative method to calculate the resulting differential densities at given precipitation depth. The differential densities of precipitating electrons derived from the analytical solutions for MELs reveal increased flattening at energies below 10-30 keV compared to a pure collisional case. This flattening becomes stronger with an increasing precipitation depth turning into a positive slope at greater precipitation depths in the chromosphere resulting in a differential density distribution with maximum that shifts towards higher energies with increase in column depth, while the differential densities combining precipitating and returning electrons are higher at lower energies than those for a pure collisional case. The resulting hard X-ray (HXR) emission produced by the beams with different initial energy fluxes and spectral indices is calculated using the MEL approach for different ratios between the differential densities of precipitating and returning electrons. The number of returning electrons can be even further enhanced by a magnetic mirroring, not considered in the present model, while dominating at lower atmospheric depths where the magnetic convergence and magnitude are the highest. The proposed MEL approach provides an opportunity to account simultaneously for both collisional and ohmic losses in flaring events, which can be used for a quick spectral fitting of HXR spectra and evaluation of a fraction of returning electrons versus precipitating ones. The semi-analytical MEL approach is used for spectral fitting to Reuven High Energy Solar Spectroscopic Imager observations of nine C, M and X class flares revealing a close fit to the observations and good resemblance to numerical FP solutions.

  12. Extended electron energy loss fine structure simulation of the local boron environment in sodium aluminoborosilicate glasses containing gadolinium

    SciTech Connect

    Qian, Morris; Li, Hong; Li, Liyu ); Strachan, Denis M. )

    2003-12-01

    Phase separation in sodium-aluminoborosilicate glasses was systematically studied as a function of Gd2O3 concentration with transmission electron microscopy (TEM), energy dispersive x-ray spectroscopy (EDS), and electron energy loss spectroscopy (EELS) methods. Gadolinium-induced phase separation in the three systems can be consistently explained by proposing that Gd cations partition to the borate-rich environments and subsequent agglomeration of the Gd-borate moieties, or short-range ordered structural groups, in the glass. Agglomeration of the Gd-borate rich environments is further discussed within the context of excess metal oxides,[Na2O]ex or[Al2O3]ex=|Na2O - Al2O3|, and excess B2O3,[B2O3]ex, available for incorporating Gd cations. Results showed that agglomeration of the Gd-borate rich environments occurred at a much lower Gd2O3 concentration in the glass without[Na2O]ex or[Al2O3]ex and at a significantly higher Gd2O3 concentration in the glass with either[Na2O]ex or[Al2O3]ex. Assuming 1BO4 : 1Gd : 2BO3 (based on literature-reported Gd-metaborate structure) as a local Gd-borate environment in glass, we introduced the saturation index of boron, SI[B]= Gd2O3/(1/3[B2O3]ex), to examine the glass susceptibility to Gd-induced phase separation for all three alkali-aluminoborosilicate systems. While our results have provided some insight to the glass structure, they also provide insight to the mechanism by which the metal oxide is dissolved into the melt. This appears to occur predominantly through boron complexation of the metal oxide.

  13. Using Terahertz Spectroscopy to Study Systems with Solar Energy Applications

    NASA Astrophysics Data System (ADS)

    Milot, Rebecca L.; Moore, Gary F.; Martini, Lauren A.; Brudvig, Gary W.; Crabtree, Robert H.; Schmuttenmaer, Charles A.

    2013-06-01

    Biomimetic solar water oxidation systems are being developed as renewable alternatives to fossil fuels. One possible design incorporates thin-film dye-sensitized nanoparticle photoanades to capture and convert visible light to charge carriers and catalysts to facilitate water oxidation. The physical properties of the dye are important due to its position as the light absorber and electron transfer initiator. Given the role that porphyrins play in photosynthesis and their synthetic tunability, they are promising components for these photoanodes. Time-Resolved THz Spectroscopy (TRTS), an optical pump/THz probe technique, is a non-contact electrical probe with proven usefulness for studying electron transfer and conductivity on a sub-picosecond timescale. Using TRTS, the efficiency and dynamics of electron injection from porphyrin dyes into metal oxide surfaces was found to be strongly influenced by the structure and photophysical properties of the dye.

  14. Tunable negligible-loss energy transfer between dipolar-coupled magnetic disks by stimulated vortex gyration

    PubMed Central

    Jung, Hyunsung; Lee, Ki-Suk; Jeong, Dae-Eun; Choi, Youn-Seok; Yu, Young-Sang; Han, Dong-Soo; Vogel, Andreas; Bocklage, Lars; Meier, Guido; Im, Mi-Young; Fischer, Peter; Kim, Sang-Koog

    2011-01-01

    A wide variety of coupled harmonic oscillators exist in nature. Coupling between different oscillators allows for the possibility of mutual energy transfer between them and the information-signal propagation. Low-energy input signals and their transport with negligible energy loss are the key technological factors in the design of information-signal processing devices. Here, utilizing the concept of coupled oscillators, we experimentally demonstrated a robust new mechanism for energy transfer between spatially separated dipolar-coupled magnetic disks - stimulated vortex gyration. Direct experimental evidence was obtained by a state-of-the-art experimental time-resolved soft X-ray microscopy probe. The rate of energy transfer from one disk to the other was deduced from the two normal modes' frequency splitting caused by dipolar interaction. This mechanism provides the advantages of tunable energy transfer rates, low-power input signals and negligible energy loss in the case of negligible intrinsic damping. Coupled vortex-state disks might be implemented in applications for information-signal processing. PMID:22355578

  15. Auger, zero-energy photoelectron, coincidence spectroscopy (AZEPECO): Chemical-site-selective Auger electron spectroscopy

    SciTech Connect

    Lee, K.; Ji, D.; Hanson, D.M.; Hulbert, S.L.; Kuiper, P.

    1993-12-31

    The Auger electron spectrum associated with decay of a core-hole on the terminal nitrogen and that associated with the central nitrogen of nitrous oxide, N{sub 2}O, are obtained individually through the use of a coincidence technique. Specifically, each of the two Auger electron spectra is obtained by detection of Auger electrons in coincidence with near zero energy (threshold) photoelectrons at the respective ionization thresholds. These zero energy electrons serve to identify the core-ionization continuum associated with the different Auger electrons. The salient features of the experimental spectra are in good agreement with theoretical calculations. The low counting rate generally associated with coincidence experiments, especially in the gas phase, is not encountered because the low energy electrons are collected over a 4{pi} solid angle. Also, velocity discrimination is accomplished by a spatial filter rather than by time-of-flight to utilize the maximum duty cycle of the synchrotron source. These data are believed to be the first examples of chemical-site-selective molecular Auger spectra.

  16. 3D Visualization of the Iron Oxidation State in FeO/Fe3O4 Core-Shell Nanocubes from Electron Energy Loss Tomography.

    PubMed

    Torruella, Pau; Arenal, Raúl; de la Peña, Francisco; Saghi, Zineb; Yedra, Lluís; Eljarrat, Alberto; López-Conesa, Lluís; Estrader, Marta; López-Ortega, Alberto; Salazar-Alvarez, Germán; Nogués, Josep; Ducati, Caterina; Midgley, Paul A; Peiró, Francesca; Estradé, Sonia

    2016-08-10

    The physicochemical properties used in numerous advanced nanostructured devices are directly controlled by the oxidation states of their constituents. In this work we combine electron energy-loss spectroscopy, blind source separation, and computed tomography to reconstruct in three dimensions the distribution of Fe(2+) and Fe(3+) ions in a FeO/Fe3O4 core/shell cube-shaped nanoparticle with nanometric resolution. The results highlight the sharpness of the interface between both oxides and provide an average shell thickness, core volume, and average cube edge length measurements in agreement with the magnetic characterization of the sample. PMID:27383904

  17. Band structure effects in the energy loss of low-energy protons and deuterons in thin films of Pt

    NASA Astrophysics Data System (ADS)

    Celedón, C. E.; Sánchez, E. A.; Salazar Alarcón, L.; Guimpel, J.; Cortés, A.; Vargas, P.; Arista, N. R.

    2015-10-01

    We have investigated experimentally and by computer simulations the energy-loss and angular distribution of low energy (E < 10 keV) protons and deuterons transmitted through thin polycrystalline platinum films. The experimental results show significant deviations from the expected velocity dependence of the stopping power in the range of very low energies with respect to the predictions of the Density Functional Theory for a jellium model. This behavior is similar to those observed in other transition metals such as Cu, Ag and Au, but different from the linear dependence recently observed in another transition metal, Pd, which belongs to the same Group of Pt in the Periodic Table. These differences are analyzed in term of the properties of the electronic bands corresponding to Pt and Pd, represented in terms of the corresponding density of states. The present experiments include also a detailed study of the angular dependence of the energy loss and the angular distributions of transmitted protons and deuterons. The results are compared with computer simulations based on the Monte Carlo method and with a theoretical model that evaluates the contributions of elastic collisions, path length effects in the inelastic energy losses, and the effects of the foil roughness. The results of the analysis obtained from these various approaches provide a consistent and comprehensive description of the experimental findings.

  18. Anomalies in the theory of viscous energy losses due to shear in rotational MEMS resonators.

    SciTech Connect

    Walsh, Timothy Francis; Klody, Kelly Anne; Jenkins, Mark W.; Dohner, Jeffrey Lynn

    2003-12-01

    In this paper, the effect of viscous wave motion on a micro rotational resonator is discussed. This work shows the inadequacy of developing theory to represent energy losses due to shear motion in air. Existing theory predicts Newtonian losses with little slip at the interface. Nevertheless, experiments showed less effect due to Newtonian losses and elevated levels of slip for small gaps. Values of damping were much less than expected. Novel closed form solutions for the response of components are presented. The stiffness of the resonator is derived using Castigliano's theorem, and viscous fluid motion above and below the resonator is derived using a wave approach. Analytical results are compared with experimental results to determine the utility of existing theory. It was found that existing macro and molecular theory is inadequate to describes measured responses.

  19. Energy losses in the D0 {beta} solenoid cryostat caused by current changes

    SciTech Connect

    Visser, A.T.

    1993-11-01

    The proposed D0 {beta} solenoid is a superconducting solenoid mounted inside an aluminum tube which supports the solenoid winding over it`s full length. This aluminum support tube, also called bobbin, is therefore very tightly coupled to magnetic flux changes caused by solenoid current variations. These current changes in the solenoid, will cause answer currents to flow in the resistive bobbin wall and therefore cause heat losses. The insertion of an external dump resistor in the solenoid current loop reduces energy dissipation inside the cryostat during a quench and will shorten the discharge time constant. This note presents a simple electrical model for the coupled bobbin and solenoid and makes it easier to understand the circuit behavior and losses. Estimates for the maximum allowable rate of solenoid current changes, based on the maximum permissible rate of losses can be made using this model.

  20. Studies of Photosynthetic Energy and Charge Transfer by Two-dimensional Fourier transform electronic spectroscopy

    NASA Astrophysics Data System (ADS)

    Ogilvie, Jennifer

    2010-03-01

    Two-dimensional (2D) Fourier transform electronic spectroscopy has recently emerged as a powerful tool for the study of energy transfer in complex condensed-phase systems. Its experimental implementation is challenging but can be greatly simplified by implementing a pump-probe geometry, where the two phase-stable collinear pump pulses are created with an acousto-optic pulse-shaper. This approach also allows the use of a continuum probe pulse, expanding the available frequency range of the detection axis and allowing studies of energy transfer and electronic coupling over a broad range of frequencies. We discuss several benefits of 2D electronic spectroscopy and present 2D data on the D1-D2 reaction center complex of Photosystem II from spinach. We discuss the ability of 2D spectroscopy to distinguish between current models of energy and charge transfer in this system.

  1. Short path length pQCD corrections to energy loss in the quark gluon plasma

    NASA Astrophysics Data System (ADS)

    Kolbe, Isobel; Horowitz, W. A.

    2016-01-01

    The twin identifications of high-pT enhancement and low-pT collective behaviour in the shockingly small systems of interacting particles created in pA collisions calls for a detailed theoretical energy loss analysis. We study the way in which energy is dissipated in the QGP created in pA collisions by calculating the short path length corrections to the DGLV energy loss formulae that have produced excellent predictions for AA collisions. We find that, shockingly, because of the large formation time assumption (used in the DGLV calculation), a highly non-trivial cancellation of correction terms results in a null short path length correction to the DGLV energy loss formula. We investigate the effect of relaxing the large formation time assumption in the final stages of the calculation and find, because of the separation distance between production and scattering centre is integrated over from 0 to ∞, ≳ 100% corrections, even in the large path length approximation employed by DGLV.

  2. Impact of the Pedestal Plasma Density on ELM Dynamics and Energy Loss Scaling

    NASA Astrophysics Data System (ADS)

    Xu, X. Q.; Ma, J. F.; Li, G. Q.; BOUT++ Collaboration

    2014-10-01

    The latest BOUT + + studies show an emerging understanding of ELM dynamics and the consistent collisionality scaling of ELM energy losses with ITPA multi-tokamak database. A series of BOUT + + simulations are conducted to investigate the scaling characteristics of the ELM energy losses vs collisionality via a density scan, while keeping the plasma cross-sectional shape, total stored energy, total plasma current, pressure profiles fixed. The neoclassical collisionality at peak gradient position increases by a factor of 3262 from 0.0019 to 6.197. The critical trend of linear simulations emerges as a transition from ballooning-dominated states at high collisionality to peeling-dominated states at low collsionality with decreasing density. Nonlinear BOUT + + simulations show a two-stage process of ELM crash evolution of (i) initial bursts of pressure blob and void creation and (ii) inward turbulence spreading as void propagation. The inward void propagation stirs the top of pedestal plasma and yields an increasing ELM size with decreasing collisionality after a series of micro-bursts. The pedestal plasma density plays a major role in determining the ELM energy loss through its effect on the edge bootstrap current and ion diamagnetic stabilization. This work was performed for USDOE by LLNL under DE-AC52-07NA27344, LLNL LDRD project 12-ERD-022 and the China Natural Science Foundation under Contract No. 10721505. LLNL-ABS-656793.

  3. X-Ray Microanalysis and Electron Energy Loss Spectrometry in the Analytical Electron Microscope: Review and Future Directions

    NASA Technical Reports Server (NTRS)

    Goldstein, J. I.; Williams, D. B.

    1992-01-01

    This paper reviews and discusses future directions in analytical electron microscopy for microchemical analysis using X-ray and Electron Energy Loss Spectroscopy (EELS). The technique of X-ray microanalysis, using the ratio method and k(sub AB) factors, is outlined. The X-ray absorption correction is the major barrier to the objective of obtaining I% accuracy and precision in analysis. Spatial resolution and Minimum Detectability Limits (MDL) are considered with present limitations of spatial resolution in the 2 to 3 microns range and of MDL in the 0.1 to 0.2 wt. % range when a Field Emission Gun (FEG) system is used. Future directions of X-ray analysis include improvement in X-ray spatial resolution to the I to 2 microns range and MDL as low as 0.01 wt. %. With these improvements the detection of single atoms in the analysis volume will be possible. Other future improvements include the use of clean room techniques for thin specimen preparation, quantification available at the I% accuracy and precision level with light element analysis quantification available at better than the 10% accuracy and precision level, the incorporation of a compact wavelength dispersive spectrometer to improve X-ray spectral resolution, light element analysis and MDL, and instrument improvements including source stability, on-line probe current measurements, stage stability, and computerized stage control. The paper reviews the EELS technique, recognizing that it has been slow to develop and still remains firmly in research laboratories rather than in applications laboratories. Consideration of microanalysis with core-loss edges is given along with a discussion of the limitations such as specimen thickness. Spatial resolution and MDL are considered, recognizing that single atom detection is already possible. Plasmon loss analysis is discussed as well as fine structure analysis. New techniques for energy-loss imaging are also summarized. Future directions in the EELS technique will be

  4. Comparison of the electronic structure of a thermoelectric skutterudite before and after adding rattlers: an electron energy loss study.

    PubMed

    Prytz, O; Saeterli, R; Løvvik, O M; Taftø, J

    2008-08-01

    Skutterudites, with rattler atoms introduced in voids in the crystal unit cell, are promising thermoelectric materials. We modify the binary skutterudite with atomic content Co(8)P(24) in the cubic crystal unit cell by adding La as rattlers in all available voids and replacing Co by Fe to maintain charge balance, resulting in La(2)Fe(8)P(24). The intention is to leave the electronic structure unaltered while decreasing the thermal conductivity due to the presence of the rattlers. We compare the electronic structure of these two compounds by studying the L-edges of P and of the transition elements Co and Fe using electron energy loss spectroscopy (EELS). Our studies of the transition metal white lines show that the 3d electron count is similar for Co and Fe in these compounds. As elemental Fe has one electron less than Co, this supports the notion that each La atom donates three electrons. The L-edges of P in these two skutterudites are quite similar, signalling only minor differences in electronic structure. This is in reasonable agreement with density functional theory (DFT) calculations, and with our multiple scattering FEFF calculations of the near edge structure. However, our experimental plasmon energies and dielectric functions deviate considerably from predictions based on DFT calculations. PMID:18042390

  5. Energy-loss and straggling of hydrogen and helium ions in silver

    NASA Astrophysics Data System (ADS)

    Lombaard, J.; Conradie, J.; Friedland, E.

    1983-10-01

    Energy-loss and straggling of protons, deuterons and 4He ions in silver were measured in the energy range between 0.14 MeV and 2.6 MeV. For energies between 0.25 and 0.60 MeV/amu the stopping powers of the hydrogen ions in silver are up to 10% lower than the semi-empirical values of Andersen and Ziegler. Better agreement is obtained with the shell-correction fit for energies above 0.6 MeV/amu. In the case of the helium ions the measured values are between 8% to 13% lower than the semi-empirical values of Ziegler. The reduced straggling for the 4He and hydrogen ions is energy independent above 0.3 MeV/amu with the He values the same as predicted by the Bohr estimate but the hydrogen values are about 15% lower.

  6. Exploring a direct measurement of quark energy loss using semi-inclusive deep inelastic scattering

    NASA Astrophysics Data System (ADS)

    Peña, C.; Brooks, W.; Hakobyan, H.; Arratia, M.

    2012-02-01

    This work consists of an evaluation of the feasibility of a direct extraction of quark energy loss from the E02-104 experiment π+ data and using semi-inclusive Deep Inelastic Scattering (DIS). The method is based on a shape analysis of the pion energy spectrum, coupled with a GENIE simulation which includes an hadronic cascade model in nuclei. The pion energy spectrum from different nuclei such as C, Fe, and Pb is compared to that of deuterium in order to find a simple energy shift, which is predicted by BDMPS if the parton energy is high enough that the medium length L is smaller than a certain critical length Lc. GENIE is used to rule out hadronic interaction effects which could also explain the same behavior observed in data.

  7. Partial intensity approach for quantitative analysis of reflection-electron-energy-loss spectra

    NASA Astrophysics Data System (ADS)

    Calliari, L.; Filippi, M.; A. Varfolomeev

    2011-08-01

    We have considered a formalism, known as partial intensity approach (PIA), previously developed to quantitatively analyze reflection electron energy loss (REEL) spectra [1,2]. The aim of the approach is, in particular, to recover the single scattering distribution of energy losses and to separate it into bulk and surface contributions, respectively referred to as the differential inverse inelastic mean free path (DIIMFP) and the differential surface excitation parameter (DSEP). As compared to [1] and [2], we have implemented a modified approach, and we have applied it to the specific geometry of the cylindrical mirror analyzer (CMA), used to acquire the REEL spectra shown here. Silicon, a material with well-defined surface and bulk plasmons, is taken as a case study to investigate the approach as a function of electron energy over the energy range typical of REELS, i.e. from 250 eV to 2 keV. Our goal is, on the one hand, to examine possible limits for the applicability of the approach and, on the other hand, to test a basic assumption of the PIA, namely that a unique DIIMFP and a unique DSEP account for REEL spectra, whatever the acquisition conditions (i.e. electron energy or angle of surface crossing) are. We find that a minimum energy exists below which the PIA cannot be applied and that the assumption of REEL spectra accounted for by unique DIIMFP and DSEP is indeed an approximation.

  8. Water loss control using pressure management: life-cycle energy and air emission effects.

    PubMed

    Stokes, Jennifer R; Horvath, Arpad; Sturm, Reinhard

    2013-10-01

    Pressure management is one cost-effective and efficient strategy for controlling water distribution losses. This paper evaluates the life-cycle energy use and emissions for pressure management zones in Philadelphia, Pennsylvania, and Halifax, Nova Scotia. It compares water savings using fixed-outlet and flow-modulated pressure control to performance without pressure control, considering the embedded electricity and chemical consumption in the lost water, manufacture of pipe and fittings to repair breaks caused by excess pressure, and pressure management. The resulting energy and emissions savings are significant. The Philadelphia and Halifax utilities both avoid approximately 130 million liters in water losses annually using flow-modulated pressure management. The conserved energy was 780 GJ and 1900 GJ while avoided greenhouse gas emissions were 50 Mg and 170 Mg a year by Philadelphia and Halifax, respectively. The life-cycle financial and environmental performance of pressure management systems compares favorably to the traditional demand management strategy of installing low-flow toilets. The energy savings may also translate to cost-effective greenhouse gas emission reductions depending on the energy mix used, an important advantage in areas where water and energy are constrained and/or expensive and greenhouse gas emissions are regulated as in California, for example. PMID:23869434

  9. Measurement of α particle energy loss in biological tissue below 2 MeV

    NASA Astrophysics Data System (ADS)

    Stella, S.; Bortolussi, S.; Bruschi, P.; Portella, C.; Altieri, S.

    2009-09-01

    The energy loss of α particles crossing biological tissue at energies between 0.8 and 2.2 MeV has been measured. This energy range is very important for boron neutron capture therapy, based on the 10B( n, α) 7Li reaction, which emits α particles with energies of 1.78 and 1.47 MeV. One of the methods used for the measurement of the boron concentration in tissue is based on the deconvolution of the α spectra obtained from neutron irradiation of thin (70 μm) tissue samples. For this technique, a knowledge of the behaviour of the energy loss of the particles in the irradiated tissue is of critical importance. In particular, the curve of the residual energy as a function of the distance travelled in the tissue must be known. In this paper, the results of an experiment carried out with an 241Am source and a series of cryostatic sections of rat-lung tissue are presented. The experimental measurements are compared with the results of Monte Carlo calculations performed with the MCNPX code.

  10. Intensity distribution analysis of cathodoluminescence using the energy loss distribution of electrons.

    PubMed

    Fukuta, Masahiro; Inami, Wataru; Ono, Atsushi; Kawata, Yoshimasa

    2016-01-01

    We present an intensity distribution analysis of cathodoluminescence (CL) excited with a focused electron beam in a luminescent thin film. The energy loss distribution is applied to the developed analysis method in order to determine the arrangement of the dipole locations along the path of the electron traveling in the film. Propagating light emitted from each dipole is analyzed with the finite-difference time-domain (FDTD) method. CL distribution near the film surface is evaluated as a nanometric light source. It is found that a light source with 30 nm widths is generated in the film by the focused electron beam. We also discuss the accuracy of the developed analysis method by comparison with experimental results. The analysis results are brought into good agreement with the experimental results by introducing the energy loss distribution. PMID:26550930

  11. Enhanced relativistic-electron-beam energy loss in warm dense aluminum.

    PubMed

    Vaisseau, X; Debayle, A; Honrubia, J J; Hulin, S; Morace, A; Nicolaï, Ph; Sawada, H; Vauzour, B; Batani, D; Beg, F N; Davies, J R; Fedosejevs, R; Gray, R J; Kemp, G E; Kerr, S; Li, K; Link, A; McKenna, P; McLean, H S; Mo, M; Patel, P K; Park, J; Peebles, J; Rhee, Y J; Sorokovikova, A; Tikhonchuk, V T; Volpe, L; Wei, M; Santos, J J

    2015-03-01

    Energy loss in the transport of a beam of relativistic electrons in warm dense aluminum is measured in the regime of ultrahigh electron beam current density over 2×10^{11}  A/cm^{2} (time averaged). The samples are heated by shock compression. Comparing to undriven cold solid targets, the roles of the different initial resistivity and of the transient resistivity (upon target heating during electron transport) are directly observable in the experimental data, and are reproduced by a comprehensive set of simulations describing the hydrodynamics of the shock compression and electron beam generation and transport. We measured a 19% increase in electron resistive energy loss in warm dense compared to cold solid samples of identical areal mass. PMID:25793822

  12. Calculation of the energy loss in giant magnetic impedance elements using the complex magnetic permeability spectra

    NASA Astrophysics Data System (ADS)

    Rustemaj, Driton; Mukherjee, Debashis

    2013-01-01

    The giant magnetic impedance (GMI) effect in ferromagnetic materials has been investigated for sensing applications. The GMI properties were evaluated via numerical solution of the complex magnetic permeability of the material. MATLAB simulation was carried out to study the frequency dependence of magnetic permeability via obtaining solutions of the Landau-Lifshitz-Gilbert (LLG) and the Maxwell's equations. The results indicate that the complex magnetic permeability peaks at a frequency of 6 GHz, corresponding to the ferromagnetic resonant (FMR) frequency, where the energy loss is maximum. A variation of the Gilbert damping parameter (α) associated with the LLG equation inversely affects this peak value. The area under the curve of complex magnetic permeability, calculated through counting the number of pixels within the image, provides an estimate of the average energy loss density within the material and appears to be consistent with the variation of the peak intensity.

  13. Impact of inward turbulence spreading on energy loss of edge-localized modes

    SciTech Connect

    Ma, C. H.; Xi, P. W.; Xu, X. Q.; Xia, T. Y.; Snyder, P. B.; Kim, S. S.

    2015-05-15

    Nonlinear two-fluid and gyrofluid simulations show that an edge localized modes (ELM) crash has two phases: fast initial crash of ion temperature perturbation on the Alfvén time scale and slow turbulence spreading. The turbulence transport phase is a slow encroachment of electron temperature perturbation due to the ELM event into pedestal region. Because of the inward turbulence spreading effect, the energy loss of an ELM decreases when density pedestal height increases. The Landau resonance yields the different cross phase-shift of ions and electrons. A 3 + 1 gyro-Landau-fluid model is implemented in BOUT++ framework. The gyrofluid simulations show that the kinetic effects have stabilizing effects on the ideal ballooning mode and the energy loss increases with the pedestal height.

  14. Impact of inward turbulence spreading on energy loss of edge-localized modesa)

    DOE PAGESBeta

    Ma, C. H.; Xu, X. Q.; Xi, P. W.; Xia, T. Y.; Snyder, P. B.; Kim, S. S.

    2015-05-18

    Nonlinear two-fluid and gyrofluid simulations show that an edge localized modes(ELM) crash has two phases: fast initial crash of ion temperature perturbation on the Alfvén time scale and slow turbulence spreading. The turbulencetransport phase is a slow encroachment of electron temperature perturbation due to the ELM event into pedestal region. Because of the inward turbulence spreading effect, the energy loss of an ELM decreases when density pedestal height increases. The Landau resonance yields the different cross phase-shift of ions and electrons. A 3 + 1 gyro-Landau-fluid model is implemented in BOUT++ framework. As a result, the gyrofluid simulations show thatmore » the kinetic effects have stabilizing effects on the ideal ballooning mode and the energy loss increases with the pedestal height.« less

  15. Energy loss for the assemblies of charged projectiles in a dusty plasma

    SciTech Connect

    Ali, S.; Murtaza, G.; Nasim, M.H.

    2005-07-15

    Expressions for the electrostatic potential and the energy loss are derived for a variety of arrays of dust grain projectiles, arranged at different orientations and separations and moving with a constant velocity along the z axis in an unmagnetized collisionless dusty plasma, using linear dielectric theory. By employing the dielectric constant of dust acoustic wave, the Debye and wake potentials are calculated for the projectiles. It is found that a projectile moving with high speed forms a negative wake behind and a shock in front of it. Further, for particular values of interspacing, the three different assemblies exhibit almost similar behavior of the energy loss and thus permit the possibility of all of them to move in unison to establish a dynamical equilibrium in a hexagonal geometry.

  16. Extremely low-loss rectification methodology for low-power vibration energy harvesters

    NASA Astrophysics Data System (ADS)

    Tiwari, R.; Ryoo, K.; Schlichting, A.; Garcia, E.

    2013-06-01

    Because of its promise for the generation of wireless systems, energy harvesting technology using smart materials is the focus of significant reported effort. Various techniques and methodologies for increasing power extraction have been tested. One of the key issues with the existing techniques is the use of diodes in the harvesting circuits with a typical voltage drop of 0.7 V. Since most of the smart materials, and other transducers, do not produce large voltage outputs, this voltage drop becomes significant in most applications. Hence, there is a need for designing a rectification method that can convert AC to DC with minimal losses. This paper describes a new mechanical rectification scheme, designed using reed switches, in a full-bridge configuration that shows the capability of working with signals from millivolts to a few hundred volts with extremely low losses. The methodology has been tested for piezoelectric energy harvesters undergoing mechanical excitation.

  17. MHD activity and energy loss during beta saturation and collapse at high beta poloidal in PBX

    SciTech Connect

    Kugel, H.W.; Sesnic, S.; Bol, K.; Chance, M.; Fishman, H.; Fonck, R.; Gammel, G.; Kaita, R.; Kaye, S.; LeBlanc, B.

    1987-10-01

    High-..beta.. experiments, in medium to high-q tokamak plasmas, exhibit a temporal ..beta.. saturation and collapse. This behavior has been attributed to ballooning, ideal kink, or tearing modes. In PBX, a unique diagnostic capability allowed studies of the relation between MHD and energy loss for neutral-beam-heated (<6 MW), mildly indented (10 to 15%), nearly steady I/sub p/ discharges that approached the Troyon-Gruber limit. Under these conditions, correlations between MHD activity and energy losses have shown that the latter can be almost fully accounted for by various long wavelength MHD instabilities and that there is no need to invoke high-n ballooning modes in PBX. 6 refs., 4 figs.

  18. Multi-excitation Raman difference spectroscopy based on modified multi-energy constrained iterative deconvolution algorithm

    NASA Astrophysics Data System (ADS)

    Zou, Wenlong; Cai, Zhijian; Zhou, Hongwu; Wu, Jianhong

    2013-12-01

    Raman spectroscopy is fast and nondestructive, and it is widely used in chemistry, biomedicine, food safety and other areas. However, Raman spectroscopy is often hampered by strong fluorescence background, especially in food additives detection and biomedicine researching. In this paper, one efficient technique was the multi-excitation Raman difference spectroscopy (MERDS) which incorporated a series of small wavelength-shift wavelengths as excitation sources. A modified multi-energy constrained iterative deconvolution (MMECID) algorithm was proposed to reconstruct the Raman Spectroscopy. Computer simulation and experiments both demonstrated that the Raman spectrum can be well reconstructed from large fluorescence background. The more excitation sources used, the better signal to noise ratio got. However, many excitation sources were equipped on the Raman spectrometer, which increased the complexity of the experimental system. Thus, a trade-off should be made between the number of excitation frequencies and experimental complexity.

  19. Energy dispersive spectroscopy using synchrotron radiation: Intensity considerations

    NASA Astrophysics Data System (ADS)

    Skelton, E. F.; Elam, W. T.; Qadri, S. B.; Webb, A. W.; Schiferl, D.

    Detailed considerations are given to the reliability of energy dependent integrated intensity data collected from the pressure cavity of a diamond-anvil pressure cell illuminated with heterochromatic radiation from a synchrotron storage ring. It is demonstrated that at least in one run, the electron beam current cannot be used to correct for energy-intensity variations of the incident beam. Rather there appears to be an additional linear relationship between the decay of the synchrotron beam and the magnitude of the background intensity.

  20. Energy dispersive spectroscopy using synchrotron radiation: Intensity considerations

    NASA Astrophysics Data System (ADS)

    Skelton, E. F.; Elam, W. T.; Qadri, S. B.; Webb, A. W.; Schiferl, D.

    1986-05-01

    Detailed considerations are given to the reliability of energy dependent integrated intensity data collected from the pressure cavity of a diamond-anvil pressure cell illuminated with heterochromatic radiation from a synchrotron storage ring. It is demonstrated that, at least in one run, the electron beam current cannot be used to correct for energy-intensity variations of the incident beam. Rather, there appears to be an additional linear relationship between the decay of the synchrotron beam and the magnitude of the background intensity.

  1. TOF Electron Energy Analyzer for Spin and Angular Resolved Photoemission Spectroscopy

    SciTech Connect

    Lebedev, Gennadi; Jozwiak, Chris; Andresen, Nord; Lanzara, Alessandra; Hussain, Zahid

    2008-07-09

    Current pulsed laser and synchrotron x-ray sources provide new opportunities for Time-Of- Flight (TOF) based photoemission spectroscopy to increase photoelectron energy resolution and efficiency compared to current standard techniques. The principals of photoelectron timing front formation, temporal aberration minimization, and optimization of electron beam transmission are presented. We have developed these concepts into a high resolution Electron Optical Scheme (EOS) of a TOF Electron Energy Analyzer (TOF-EEA) for photoemission spectroscopy. The EOS of the analyzer includes an electrostatic objective lens, three columns of transport lenses and a 90 degree energy band pass filter (BPF). The analyzer has two modes of operation: Spectrometer Mode (SM) with straight passage of electrons through the EOS undeflected by the BPF, allowing the entire spectrum to be measured, and Monochromator Mode (MM) in which the BPF defines a certain energy window inside the scope of the electron energy spectrum.

  2. Electron Energy-Loss Spectroscopy (EELS) of Fe-bearing Sheet Silicates in CM Chondrites

    NASA Technical Reports Server (NTRS)

    Zega, Thomas J.; Garvie, Laurence A. J.; Buseck, Peter R.

    2003-01-01

    The primitive character and hydrated mineralogy of the CM chondrites offers insight into some of the earliest reactions between solids and water. Such reactions profoundly affected the matrices and fine-grained rims (FGRs) [1-4], two of the most significant components of these meteorites [5]. We are using EELS combined with a transmission electron microscope (TEM) to investigate the compositions of Fe-bearing minerals, with emphasis on determining oxidation states and quantification of oxidation-state ratios. Iron is among the most abundant elements in the solar system and it can occur naturally in three oxidation states: Fe0, Fe2+, and Fe3+. Determination of oxidation- state ratios is useful because they can be used to infer the redox conditions under which the minerals formed or were last equilibrated [6, 7]. We are particularly interested in understanding how the oxidation state of Fe was affected by the aqueous reactions of the CM chondrites.

  3. New algorithms for the Vavilov distribution calculation and the corresponding energy loss sampling

    SciTech Connect

    Chibani, O. |

    1998-10-01

    Two new algorithms for the fast calculation of the Vavilov distribution within the interval 0.01 {le} {kappa} {le} 10, where neither the Gaussian approximation nor the Landau distribution may be used, are presented. These algorithms are particularly convenient for the sampling of the corresponding random energy loss. A comparison with the exact Vavilov distribution for the case of protons traversing Al slabs is given.

  4. Mass by Energy Loss Quantitation as a Practical Sub-Microgram Balance

    SciTech Connect

    Palmblad, M; Bench, G; Vogel, J S

    2004-09-28

    A simple device integrating a thin film support and a standard microcentrifuge tube can be used for making solutions of accurately known concentration of any organic compound in a single step, avoiding serial dilution and the use of microgram balances. Nanogram to microgram quantities of organic material deposited on the thin film are quantified by ion energy loss and transferred to the microcentrifuge tube with high recovery.

  5. APPARATUS FOR MINIMIZING ENERGY LOSSES FROM MAGNETICALLY CONFINED VOLUMES OF HOT PLASMA

    DOEpatents

    Post, R.F.

    1961-10-01

    An apparatus is described for controlling electron temperature in plasma confined in a Pyrotron magnetic containment field. Basically the device comprises means for directing low temperature electrons to the plasma in controlled quantities to maintain a predetermined optimum equilibrium electron temperature whereat minimum losses of plasma ions due to ambipolar effects and energy damping of the ions due to dynamical friction with the electrons occur. (AEC)

  6. Antiferroelectric Thin-Film Capacitors with High Energy-Storage Densities, Low Energy Losses, and Fast Discharge Times.

    PubMed

    Ahn, Chang Won; Amarsanaa, Gantsooj; Won, Sung Sik; Chae, Song A; Lee, Dae Su; Kim, Ill Won

    2015-12-01

    We demonstrate a capacitor with high energy densities, low energy losses, fast discharge times, and high temperature stabilities, based on Pb(0.97)Y(0.02)[(Zr(0.6)Sn(0.4))(0.925)Ti(0.075)]O3 (PYZST) antiferroelectric thin-films. PYZST thin-films exhibited a high recoverable energy density of U(reco) = 21.0 J/cm(3) with a high energy-storage efficiency of η = 91.9% under an electric field of 1300 kV/cm, providing faster microsecond discharge times than those of commercial polypropylene capacitors. Moreover, PYZST thin-films exhibited high temperature stabilities with regard to their energy-storage properties over temperatures ranging from room temperature to 100 °C and also exhibited strong charge-discharge fatigue endurance up to 1 × 10(7) cycles. PMID:26606502

  7. Argon hydrochloride, Ar.HCl, bond energy by infrared spectroscopy

    NASA Technical Reports Server (NTRS)

    Miziolek, A. W.; Pimentel, G. C.

    1976-01-01

    The infrared absorption of argon (200 to 760 torr) and hydrogen chloride (2 to 6 torr) mixtures is reexamined in the missing Q branch region (spectral region between 2860 and 3010 wavelength/cm) at temperatures ranging from 195 to 298 K. The temperature dependence of two absorption features of the argon hydrogen chloride complex, at 2887 and 2879 wavelength/cm, leads to a bond energy estimate that depends on the assumptions made about the internal degrees of freedom of the complex. It is shown that agreement with experiment can be reached for well depths near 1.2 kcal/mole. This result is relatively insensitive to the choice of the vibrational frequencies and anharmonicities, but does depend on the extent to which the energy level manifolds are truncated to avoid molecular excitation in excess of the bond energy. The bond energy is found to deviate from the commonly accepted value of 0.4 kcal/mole. Possible causes for the discrepancy are considered.

  8. Impact of inward turbulence spreading on energy loss of edge-localized modes

    NASA Astrophysics Data System (ADS)

    Ma, Chenhao

    2014-10-01

    BOUT++ six-field Landau-fluid simulations show that an ELM crash has two phases: fast initial crash of ion temperature profile on the order of Alfven time scale near the peak gradient region and slow electron inward turbulence spreading from the ELM crash event. Both of them contribute to the ELM energy loss. However, the conducted ELM energy loss dominates over the convected ELM energy loss, which remains almost constant after the initial crash. The total ELM energy loss is mainly determined by the MHD turbulence spreading when the pedestal temperature height is large. The inward front propagation of electron temperature perturbation spreads into the linearly stable zone, while the ion perturbation front has much less spreading. The electron temperature fluctuation peaks on the rational surfaces and the front jumps gradually inwards towards neighboring rational surfaces. The electron wave-particle resonances via Landau closure provide a relatively strong parallel damping effect on the electron temperature perturbation and induce a large cross-phase shift of about π / 2 angle between ExB velocity and the ion temperature, which yields almost no spreading for ion temperature and density fluctuation. When pedestal temperature height increases, the cross-phase shift of electron decreases and is close to π / 4 angle which yields a large turbulence spreading and generates the large electron conducted energy loss. The front propagation stops at the position where the radial turbulent correlation length is shorter than the magnetic surface spacing. The energy burst of an ELM is controlled by the magnetic shear profile, the characteristic front propagating velocity and the turbulence correlation time. The inward turbulence spreading is mainly driven by (1) a series of micro-crashes due to a localized steepening of profile and (2) the magnetic flutter. The impact of other kinetic effects, such as full FLR effect and toroidal resonance, will be presented via simulations of

  9. Energy loss process analysis for radiation degradation and immediate recovery of amorphous silicon alloy solar cells

    NASA Astrophysics Data System (ADS)

    Sato, Shin-ichiro; Beernink, Kevin; Ohshima, Takeshi

    2015-06-01

    Performance degradation of a-Si/a-SiGe/a-SiGe triple-junction solar cells due to irradiation of silicon ions, electrons, and protons are investigated using an in-situ current-voltage measurement system. The performance recovery immediately after irradiation is also investigated. Significant recovery is always observed independent of radiation species and temperature. It is shown that the characteristic time, which is obtained by analyzing the short-circuit current annealing behavior, is an important parameter for practical applications in space. In addition, the radiation degradation mechanism is discussed by analyzing the energy loss process of incident particles (ionizing energy loss: IEL, and non-ionizing energy loss: NIEL) and their relative damage factors. It is determined that ionizing dose is the primarily parameter for electron degradation whereas displacement damage dose is the primarily parameter for proton degradation. This is because the ratio of NIEL to IEL in the case of electrons is small enough to be ignored the damage due to NIEL although the defect creation ratio of NIEL is much larger than that of IEL in the cases of both protons and electrons. The impact of “radiation quality effect” has to be considered to understand the degradation due to Si ion irradiation.

  10. Energy Loss Calculations for Target Thickness Determinations using SRIM and Excel

    NASA Astrophysics Data System (ADS)

    Pawlak, A. S.; Greene, J. P.

    2011-10-01

    The thickness of a thin target foil can be determined by measuring the energy loss of alpha particles that travel through it. In the Target Laboratory of the Physics Division at Argonne National Laboratory (ANL), this is accomplished by measuring the energy loss of the 5812 keV alpha particles emitted by a 2 49 Cf source using a silicon detector set-up. The energy loss is translated into the target foil thickness using the stopping power for 4He in the target material obtained from the stopping/range tables provided by SRIM. This calculation has until recently been carried out using a program developed for this purpose, ``ENELOSS.'' This program uses the stopping/range tables from the original work published by Ziegler. Additionally, due to its design, ENELOSS is unable to easily accommodate targets made from compounds. In order to perform theses measurements using the most recent SRIM data, and to better calculate the thickness of compound targets, we have developed a ``Thickness Calculation'' spreadsheet using Microsoft Excel. This spreadsheet approach is not limited to elemental targets and employs stopping/range tables from the most recent edition of SRIM available on the web. The calculations obtained allow for more accurate target thicknesses and automates the process conveniently for repetitive measurements. This work was supported by the U.S. DoE, Nuclear Physics Division, under Contract No. W-31-109-Eng-38.

  11. The Čerenkov limit of Si, GaAs and GaP in electron energy loss spectrometry.

    PubMed

    Horák, Michal; Stöger-Pollach, Michael

    2015-10-01

    Since the advent of monochromated electron energy loss spectrometry (EELS) the experimental detection of band gaps in semiconducting materials is of great importance. In the non-relativistic limit of this technique the onset of the inelastic signal represents the band gap. But due to relativistic energy losses, like Čerenkov losses and the corresponding light guiding modes, appearing at high beam energies the band gap is usually hidden. The highest beam energy, which does not excite relativistic losses in a certain material, is called the Čerenkov limit of the material. In this work the low loss EELS signals of Si, GaAs and GaP are measured at various beam energies and the calculated Čerenkov limits are experimentally confirmed. PMID:26094202

  12. Vanishing electronic energy loss of very slow light ions in insulators with large band gaps.

    PubMed

    Markin, S N; Primetzhofer, D; Bauer, P

    2009-09-11

    Electronic energy loss of light ions in nanometer films of materials with large band gaps has been studied for very low velocities. For LiF, a threshold velocity is observed at 0.1 a.u. (250 eV/u), below which the ions move without transferring energy to the electronic system. For KCl, a lower (extrapolated) threshold velocity is found, identical for H and He ions. For SiO2, no clear velocity threshold is observed for He particles. For protons and deuterons, electronic stopping is found to perfectly fulfill velocity scaling, as expected for binary ion-electron interaction. PMID:19792368

  13. Vanishing Electronic Energy Loss of Very Slow Light Ions in Insulators with Large Band Gaps

    SciTech Connect

    Markin, S. N.; Primetzhofer, D.; Bauer, P.

    2009-09-11

    Electronic energy loss of light ions in nanometer films of materials with large band gaps has been studied for very low velocities. For LiF, a threshold velocity is observed at 0.1 a.u. (250 eV/u), below which the ions move without transferring energy to the electronic system. For KCl, a lower (extrapolated) threshold velocity is found, identical for H and He ions. For SiO{sub 2}, no clear velocity threshold is observed for He particles. For protons and deuterons, electronic stopping is found to perfectly fulfill velocity scaling, as expected for binary ion-electron interaction.

  14. Introducing electron capture into the unitary-convolution-approximation energy-loss theory at low velocities

    SciTech Connect

    Schiwietz, G.; Grande, P. L.

    2011-11-15

    Recent developments in the theoretical treatment of electronic energy losses of bare and screened ions in gases are presented. Specifically, the unitary-convolution-approximation (UCA) stopping-power model has proven its strengths for the determination of nonequilibrium effects for light as well as heavy projectiles at intermediate to high projectile velocities. The focus of this contribution will be on the UCA and its extension to specific projectile energies far below 100 keV/u, by considering electron-capture contributions at charge-equilibrium conditions.

  15. Competing effects of electronic and nuclear energy loss on microstructural evolution in ionic-covalent materials

    SciTech Connect

    Zhang, Yanwen; Varga, Tamas; Ishimaru, Dr. Manabu; Edmondson, Dr. Philip; Xue, Haizhou; Liu, Peng; Moll, Sandra; Namavar, Fereydoon; Hardiman, Chris; Shannon, Prof. Steven; Weber, William J

    2014-01-01

    Ever increasing energy needs have raised the demands for advanced fuels and cladding materials that withstand the extreme radiation environments with improved accident tolerance over a long period of time. Ceria (CeO2) is a well known ionic conductor that is isostructural with urania and plutonia-based nuclear fuels. In the context of nuclear fuels, immobilization and transmutation of actinides, CeO2 is a model system for radiation effect studies. Covalent silicon carbide (SiC) is a candidate for use as structural material in fusion, cladding material for fission reactors, and an inert matrix for the transmutation of plutonium and other radioactive actinides. Understanding microstructural change of these ionic-covalent materials to irradiation is important for advanced nuclear energy systems. While displacements from nuclear energy loss may be the primary contribution to damage accumulation in a crystalline matrix and a driving force for the grain boundary evolution in nanostructured materials, local non-equilibrium disorder and excitation through electronic energy loss may, however, produce additional damage or anneal pre-existing defect. At intermediate transit energies where electronic and nuclear energy losses are both significant, synergistic, additive or competitive processes may evolve that affect the dynamic response of materials to irradiation. The response of crystalline and nanostructured CeO2 and SiC to ion irradiation are studied under different nuclear and electronic stopping powers to describe some general material response in this transit energy regime. Although fast radiation-induced grain growth in CeO2 is evident with no phase transformation, different fluence and dose dependence on the growth rate is observed under Si and Au irradiations. While grain shrinkage and amorphization are observed in the nano-engineered 3C SiC with a high-density of stacking faults embedded in nanosize columnar grains, significantly enhanced radiation resistance is

  16. Determination of molecular spectroscopic parameters and energy-transfer rates by double-resonance spectroscopy

    NASA Technical Reports Server (NTRS)

    Steinfeld, J. I.; Foy, B.; Hetzler, J.; Flannery, C.; Klaassen, J.; Mizugai, Y.; Coy, S.

    1990-01-01

    The spectroscopy of small to medium-size polyatomic molecules can be extremely complex, especially in higher-lying overtone and combination vibrational levels. The high density of levels also complicates the understanding of inelastic collision processes, which is required to model energy transfer and collision broadening of spectral lines. Both of these problems can be addressed by double-resonance spectroscopy, i.e., time-resolved pump-probe measurements using microwave, infrared, near-infrared, and visible-wavelength sources. Information on excited-state spectroscopy, transition moments, inelastic energy transfer rates and propensity rules, and pressure-broadening parameters may be obtained from such experiments. Examples are given for several species of importance in planetary atmospheres, including ozone, silane, ethane, and ammonia.

  17. Time-of-flight spectroscopy: energy calibration and consistensy check

    NASA Astrophysics Data System (ADS)

    Stunault, A.; Andersen, K. H.; Blanc, Y.; Fåk, B.; Godfrin, H.; Guckelsberger, K.; Scherm, R.

    1992-06-01

    A method for calibration of the energy transfers at a time-of-flight (TOF) spectrometer is presented: flight pamths and wavelength are determined to 10 -3 using the arrival times of neutron pulses and prompt capture γs from the sample. We also developed a method to check the reproducibility of a series of TFO data sets, each with over 50 000 data points.

  18. Radiant energy and insensible water loss in the premature newborn infant nursed under a radiant warmer.

    PubMed

    Baumgart, S

    1982-10-01

    Radiant warmers are a powerful and efficient source of heat serving to warm the cold-stressed infant acutely and to provide uninterrupted maintenance of body temperature despite a multiplicity of nursing, medical, and surgical procedures required to care for the critically ill premature newborn in today's intensive care nursery. A recognized side-effect of radiant warmer beds is the now well-documented increase in insensible water loss through evaporation from an infant's skin. Particularly the very-low-birth-weight, severely premature, and critically ill neonate is subject to this increase in evaporative water loss. The clinician caring for the infant is faced with the difficult problem of fluid and electrolyte balance, which requires vigilant monitoring of all parameters of fluid homeostasis. Compounding these difficulties, other portions of the electromagnetic spectrum (for example, phototherapy) may affect an infant's fluid metabolism by mechanisms that are not well understood. The role of plastic heat shielding in reducing large insensible losses in infants nursed on radiant warmer beds is currently under intense investigation. Apparently, convective air currents and not radiant heat energy may be the cause of the observed increase in insensible water loss in the intensive care nursery. A thin plastic blanket may be effective in reducing evaporative water loss by diminishing an infant's exposure to convective air currents while being nursed on an open radiant warmer bed. A rigid plastic body hood, although effective as a radiant heat shield, is not as effective in preventing exposure to convection in the intensive care nursery and, therefore, is not as effective as the thin plastic blanket in reducing insensible water loss. Care should be exercised in determining the effect of heat shielding on all parameters of heat exchange (convection, evaporation, and radiation) before application is made to the critically ill premature infant nursed on an open radiant

  19. Photon backscattering tissue characterization by energy dispersive spectroscopy evaluations.

    PubMed

    Tartari, A; Casnati, E; Fernandez, J E; Felsteiner, J; Baraldi, C

    1994-02-01

    Techniques for in vivo tissue characterization based on scattered photons have usually been confined to evaluating coherent and Compton peaks. However, information can also be obtained from the energy analysis of the Compton scattered distribution. This paper looks at the extension of a technique validated by the authors for characterizing tissues composed of low-atomic-number elements. To this end, an EDXRS (energy dispersive x-ray spectrometry) computer simulation procedure was performed and applied to test the validity of a figure of merit able to characterize binary compounds. This figure of merit is based on the photon fluence values in a restricted energy interval of the measured distribution of incoherently scattered photons. After careful experimental tests with 59.54 keV incident photons at scattering angles down to 60degrees, the simulation procedure was applied to quasi-monochromatic and polychromatic high-radiance sources. The results show that the characterization by the figure of merit, which operates satisfactorily with monochromatic sources, is unsatisfactory in the latter cases, which seem to favour a different parameter for compound characterization. PMID:15552121

  20. Effects of Diet Composition on Postprandial Energy Availability during Weight Loss Maintenance

    PubMed Central

    Walsh, Carolyn O.; Ebbeling, Cara B.; Swain, Janis F.; Markowitz, Robert L.; Feldman, Henry A.; Ludwig, David S.

    2013-01-01

    Background The major circulating metabolic fuels regulate hunger, and each is affected by dietary composition. An integrated measure of postprandial energy availability from circulating metabolic fuels may help inform dietary recommendations for weight maintenance after weight loss. Aim We examined the effect of low-fat (LF, 60% of energy from carbohydrate, 20% fat, 20% protein), low-glycemic index (LGI, 40%–40%-20%), and very low-carbohydrate (VLC, 10%–60%-30%) diets on total postprandial metabolic fuel energy availability (EA) during weight loss maintenance. Methods Eight obese young adults were fed a standard hypocaloric diet to produce 10–15% weight loss. They were then provided isocaloric LF, LGI, and VLC diets in a randomized crossover design, each for a 4-week period of weight loss maintenance. At the end of each dietary period, a test meal representing the respective diet was provided, and blood samples were obtained every 30 minutes for 5 hours. The primary outcome was EA, defined as the combined energy density (circulating level×relative energy content) of glucose, free fatty acids, and β-hydroxybutyrate. Secondary outcomes were individual metabolic fuels, metabolic rate, insulin, glucagon, cortisol, epinephrine, and hunger ratings. Respiratory quotient was a process measure. Data were analyzed by repeated-measures analysis of variance, with outcomes compared in the early (30 to 150 min) and late (180 to 300 min) postprandial periods. Results EA did not differ between the test meals during the early postprandial period (p = 0.99). However, EA in the late postprandial period was significantly lower after the LF test meal than the LGI (p<0.0001) and VLC (p<0.0001) test meals. Metabolic rate also differed in the late postprandial period (p = 0.0074), with higher values on the VLC than LF (p = 0.0064) and LGI (p = 0.0066) diets. Conclusion These findings suggest that an LF diet may adversely affect postprandial EA and risk for weight

  1. Methane output of tortoises: its contribution to energy loss related to herbivore body mass.

    PubMed

    Franz, Ragna; Soliva, Carla R; Kreuzer, Michael; Hatt, Jean-Michel; Furrer, Samuel; Hummel, Jürgen; Clauss, Marcus

    2011-01-01

    An increase in body mass (M) is traditionally considered advantageous for herbivores in terms of digestive efficiency. However, recently increasing methane losses with increasing M were described in mammals. To test this pattern in non-mammal herbivores, we conducted feeding trails with 24 tortoises of various species (M range 0.52-180 kg) fed a diet of grass hay ad libitum and salad. Mean daily dry matter and gross energy intake measured over 30 consecutive days scaled to M(0.75 (95%CI 0.64-0.87)) and M(0.77 (95%CI 0.66-0.88)), respectively. Methane production was measured over two consecutive days in respiration chambers and scaled to M(1.03 (95%CI 0.84-1.22)). When expressed as energy loss per gross energy intake, methane losses scaled to 0.70 (95%CI 0.47-1.05) M(0.29 (95%CI 0.14-0.45)). This scaling overlaps in its confidence intervals to that calculated for nonruminant mammals 0.79 (95%CI 0.63-0.99) M(0.15 (95%CI 0.09-0.20)), but is lower than that for ruminants. The similarity between nonruminant mammals and tortoises suggest a common evolution of the gut fauna in ectotherms and endotherms, and that the increase in energetic losses due to methane production with increasing body mass is a general allometric principle in herbivores. These findings add evidence to the view that large body size itself does not necessarily convey a digestive advantage. PMID:21408074

  2. Pericardial Fat Loss in Postmenopausal Women under Conditions of Equal Energy Deficit

    PubMed Central

    BRINKLEY, TINA E.; DING, JINGZHONG; CARR, J. JEFFREY; NICKLAS, BARBARA J.

    2013-01-01

    Weight loss induced by caloric restriction (CR) or aerobic exercise can reduce pericardial fat, and these reductions may help improve cardiovascular health. Purpose We examined whether combining CR with aerobic exercise enhances pericardial fat loss compared with a CR-only intervention designed to elicit equivalent reductions in body weight. We also examined the relationship between changes in pericardial fat and changes in maximal oxygen consumption (V̇O2max), a measure of cardiorespiratory fitness. Methods Thirty-two abdominally obese postmenopausal women (mean age = 58 yr; 78% Caucasian) were randomly assigned to one of three interventions of equal energy deficit (~2800 kcal·wk−1) for 20 wk: CR only (n = 8), CR + moderate-intensity exercise (n = 15), or CR + vigorous-intensity exercise (n = 9). The volume of pericardial fat around the coronary arteries was measured by computed tomography. Results Women in the CR, CR + moderate-intensity, and CR + vigorous-intensity groups had similar baseline characteristics. The mean ± SD value for pericardial fat before weight loss was 79.07 ± 32.90 cm3 (range = 34.04–152.74 cm3), with no difference among groups (P = 0.89). All three interventions significantly reduced body weight (15%), waist circumference (10%), and abdominal visceral fat (28%) to a similar degree. There was also a 17% reduction in pericardial fat (−12.75 ± 6.29 cm3, P < 0.0001), which did not differ among groups (P = 0.84). Changes in pericardial fat were inversely correlated with changes in V̇O2max (r = −0.37, P = 0.05), but not after adjusting for intervention group and change in body weight. Conclusions Weight loss interventions of equal energy deficit have similar effects on pericardial fat in postmenopausal women, regardless of whether the energy deficit is due to CR alone or CR plus aerobic exercise. PMID:20881884

  3. X-ray photo-emission and energy dispersive spectroscopy of HA coated titanium

    SciTech Connect

    Drummond, J.L.; Steinberg, A.D.; Krauss, A.R.

    1997-08-01

    The purpose of this study was to determine the chemical composition changes of hydroxyapatite (HA) coated titanium using surface analysis (x-ray photo-emission) and bulk analysis (energy dispersive spectroscopy). The specimens examined were controls, 30 minutes and 3 hours aged specimens in distilled water or 0.2M sodium phosphate buffer (pH 7.2) at room temperature. Each x-ray photo-emission cycle consisted of 3 scans followed by argon sputtering for 10 minutes for a total of usually 20 cycles, corresponding to a sampling depth of {approximately} 1500 {angstrom}. The energy dispersive spectroscopy analysis was on a 110 by 90 {mu}m area for 500 sec. Scanning electron microscopy examination showed crystal formation (3P{sub 2}O{sub 5}*2CAO*?H{sub 2}O by energy dispersive spectroscopy analysis) on the HA coating for the specimens aged in sodium phosphate buffer. The x-ray photo-emission results indicated the oxidation effect of water on the titanium (as TiO{sub 2}) and the effect of the buffer to increase the surface concentration of phosphorous. No differences in the chemical composition were observed by energy dispersive spectroscopy analysis. The crystal growth was only observed for the sodium phosphate buffer specimens and only on the HA surface.

  4. A low energy ion source for electron capture spectroscopy

    SciTech Connect

    Tusche, C.; Kirschner, J.

    2014-06-15

    We report on the design of an ion source for the production of single and double charged Helium ions with kinetic energies in the range from 300 eV down to 5 eV. The construction is based on a commercial sputter ion gun equipped with a Wien-filter for mass/charge separation. Retardation of the ions from the ionizer potential (2 keV) takes place completely within the lens system of the sputter gun, without modification of original parts. For 15 eV He{sup +} ions, the design allows for beam currents up to 30 nA, limited by the space charge repulsion in the beam. For He{sup 2+} operation, we obtain a beam current of 320 pA at 30 eV, and 46 pA at 5 eV beam energy, respectively. In addition, operating parameters can be optimized for a significant contribution of metastable He*{sup +} (2s) ions.

  5. Experimental and theoretical study of the energy loss of C and O in Zn

    SciTech Connect

    Cantero, E. D.; Lantschner, G. H.; Arista, N. R.; Montanari, C. C.; Miraglia, J. E.; Behar, M.; Fadanelli, R. C.

    2011-07-15

    We present a combined experimental-theoretical study of the energy loss of C and O ions in Zn in the energy range 50-1000 keV/amu. This contribution has a double purpose, experimental and theoretical. On the experimental side, we present stopping power measurements that fill a gap in the literature for these projectile-target combinations and cover an extended energy range, including the stopping maximum. On the theoretical side, we make a quantitative test on the applicability of various theoretical approaches to calculate the energy loss of heavy swift ions in solids. The description is performed using different models for valence and inner-shell electrons: a nonperturbative scattering calculation based on the transport cross section formalism to describe the Zn valence electron contribution, and two different models for the inner-shell contribution: the shellwise local plasma approximation (SLPA) and the convolution approximation for swift particles (CasP). The experimental results indicate that C is the limit for the applicability of the SLPA approach, which previously was successfully applied to projectiles from H to B. We find that this model clearly overestimates the stopping data for O ions. The origin of these discrepancies is related to the perturbative approximation involved in the SLPA. This shortcoming has been solved by using the nonperturbative CasP results to describe the inner-shell contribution, which yields a very good agreement with the experiments for both C and O ions.

  6. Determination of the Exciton Binding Energy Using Photothermal and Photoluminescence Spectroscopy

    NASA Astrophysics Data System (ADS)

    Strzałkowski, K.; Zakrzewski, J.; Maliński, M.

    2013-04-01

    In this paper, experimental photoluminescence (PL) and piezoelectric photothermal (PPT) spectra of selected II-VI binary crystals are presented and analyzed. The quantitative analysis of the photothermal spectra was performed using a modified and extended Jackson-Amer model. The values of the bandgap energies of investigated semiconductors were computed from the PT amplitude and phase spectra. From the temperature dependence of the exciton emission so-called "excitonic energy gaps" have been determined. It follows from the theory that the exciton binding energy is the difference of these two values of energy gaps derived from PPT and PL spectroscopy.

  7. Relation of ultrasonic energy loss factors and constituent properties in unidirectional composites. [graphite-epxoy composite materials

    NASA Technical Reports Server (NTRS)

    Williams, J. H., Jr.; Lee, S. S.; Nayebhashemi, H.

    1979-01-01

    A model is developed relating composite constituents properties with ultrasonic energy loss factors for longitudinal waves propagating in the principal directions of a unidirectional graphite/epoxy fiber composite. All the constituents are assumed to behave as linear viscoelastic materials with energy dissipation properties defined by loss factors. It is found that by introducing a new constituent called the interface material, the composite and constituent properties can be brought into consistency with simple series and parallel models. An expression relating the composite loss factors to the loss factors of the constituents is derived and its coefficients are evaluated.

  8. Chimney related energy losses in oil-fired heating systems: Configuration effects and venting alternatives

    SciTech Connect

    Butcher, T.; McDonald, R.; Krajewski, R.; Batey, J.

    1990-12-01

    Conventional venting systems for oil-fired residential heating equipment include the flue connector, a barometric damper, and the chimney. This venting arrangement is directly responsible for some of the annual energy losses associated with these heating installations. In the work described in this report a study of the relevant characteristics of burners and dampers was done to permit these energy losses to be estimated as a function of the installation details. The purpose of this work is to determine the potential energy savings which might be realized from alternative venting methods in a wide range of situations. The basic draft/flow characteristics of barometric dampers were measured using a flow tunnel arrangement under cold (no combustion) conditions. A range of damper diameters and draft settings were used. Off-cycle draft/flow relations for several burners and heating units with the burner ports sealed were also measured over a range of conditions. Recently, oil burners have become available which have significantly higher static pressure fans. The excess air level provided by these burners is much less sensitive to variations in draft and burners of this type might be operated without a barometric damper. Burner fan performance curves for both high and low static pressure units have been measured. Flows through the heating unit and barometric damper flows have been calculated during the on- and off-cycle for a range of configurations as a function of outdoor temperature. The annual energy losses due to the venting system were calculated using a bin method. The calculated flows were compared with available field data. To supplement the available data some additional field measurements were taken during this project and are described in this report. 19 refs., 42 figs., 7 tabs.

  9. Inelastic mean-free paths and surface excitation parameters by absolute reflection electron-energy loss measurements

    NASA Astrophysics Data System (ADS)

    Nagatomi, T.; Goto, K.

    2007-06-01

    An analytical approach is proposed for simultaneously determining the inelastic mean-free path (IMFP), the surface excitation parameter (SEP), and the differential SEP (DSEP) in absolute units from an absolute reflection electron energy loss spectroscopy (REELS) spectrum under the assumption that the normalized differential inelastic mean-free path for bulk excitations and the elastic scattering cross section are known. This approach was applied to an analysis of REELS spectra for Ni, and the IMFP, SEP, and DSEP in Ni for 300-3000eV electrons were determined. The resulting IMFPs showed good agreement with those calculated using the TPP-2M predictive equations and with those calculated from optical data. The deduced DSEPs show a reasonable agreement with those theoretically predicted. The obtained SEPs were compared with those calculated using several predictive equations. The present SEP results agreed well with the Chen formula with a material parameter proposed for Ni. The present approach has high potential for the experimental determination of IMFPs, SEPs, and DSEPs in absolute units.

  10. High resolution energy loss research: Si compounds and ceramics. Progress report, January 2, 1991--January 1, 1992

    SciTech Connect

    Carpenter, R.W.; Lin, S.H.

    1992-02-01

    Our current investigation of the structure and chemistry of whisker/matrix interfaces and matrix grain boundaries in SiC whisker reinforced Si{sub 3}N{sub 4} composites has been completed. We examined these interfaces and boundaries in four composites whose starting materials and processing were identical except for the SiC whiskers themselves, which were from four different sources: American matrix, Nikkei, Huber and Tokai. Thus, differences in interfaces among the composites are attributable to differences in the whiskers. The results showed that oxygen-rich amorphous interfacial layers were discontinuous in all whisker/matrix interfaces and continuous in all matrix grain boundaries. Further, we used position-resolved high spatial resolution electron energy loss spectroscopy to show that the ``chemical interface width`` is much wider than the ``geometric or structural interface width`` at both types of interfaces in all four composites. The geometric interface widths were determined from high resolution transmission electron microscope images of edge-on interfaces.

  11. The Effect Of Electronic Energy Loss On Irradiation-induced Grain Growth In Nanocrystalline Oxides

    SciTech Connect

    Zhang, Yanwen; Aidhy, Dilpuneet S.; Varga, Tamas; Moll, Sandra; Edmondson, Philip D.; Namavar, Fereydoon; Jin, Ke; Ostrouchov, Christopher N.; Weber, William J.

    2014-03-03

    Grain growth of nanocrystalline materials is generally thermally activated, but can also be driven by irradiation at much lower temperature. In nanocrystalline ceria and zirconia, energetic ions deposit their energy to both atomic nuclei and electrons. Our experimental results have shown that irradiationinduced grain growth is dependent on the total energy deposited, where electronic energy loss and elastic collisions between atomic nuclei both contribute to the production of disorder and grain growth. Our atomistic simulations reveal that a high density of disorder near grain boundaries leads to locally rapid grain movement. The additive effect from both electronic excitation and atomic collision cascades on grain growth demonstrated in this work opens up new possibilities for controlling grain sizes to improve functionality of nanocrystalline materials.

  12. Reduction in tribological energy losses in the transportation and electric utilities sectors

    SciTech Connect

    Pinkus, O.; Wilcock, D.F.; Levinson, T.M.

    1985-09-01

    This report is part of a study of ways and means of advancing the national energy conservation effort, particularly with regard to oil, via progress in the technology of tribology. The report is confined to two economic sectors: transportation, where the scope embraces primarily the highway fleets, and electric utilities. Together these two sectors account for half of the US energy consumption. Goal of the study is to ascertain the energy sinks attributable to tribological components and processes and to recommend long-range research and development (R and D) programs aimed at reducing these losses. In addition to the obvious tribological machine components such as bearings, piston rings, transmissions and so on, the study also extends to processes which are linked to tribology indirectly such as wear of machine parts, coatings of blades, high temperature materials leading to higher cycle efficiencies, attenuation of vibration, and other cycle improvements.

  13. An experimental study of energy loss mechanisms and efficiency consideration in the low power dc arcjet

    NASA Technical Reports Server (NTRS)

    Curran, F. M.

    1985-01-01

    The potential utility of the low power dc arcjet in auxiliary propulsion was investigated. It was indicated that improvements in the areas of stability, energy efficiency, reliability, and electrode erosion are necessary to obtain a useful device. A water-cooled arcjet simulator was tested to investigate both the energy loss mechanisms at the electrodes and the stability of different conventional arcjet configurations in the presence of a vortex flow field. It is shown that in certain configurations only 25 to 30% of the input energy is lost to the electrodes. It is also shown that vortex stabilization is not difficult to obtain in many cases at the flow rates used and that a careful starting procedure is effective in minimizing electrode damage.

  14. An experimental study of energy loss mechanisms and efficiency considerations in the low power dc arcjet

    NASA Technical Reports Server (NTRS)

    Curran, F. M.

    1985-01-01

    The potential utility of the low power dc arcjet in auxiliary propulsion was investigated. It was indicated that improvements in the areas of stability, energy efficiency, reliability, and electrode erosion are necessary to obtain a useful device. A water-cooled arcjet simulator was tested to investigate both the energy loss mechanisms at the electrodes and the stability of different conventional arcjet configurations in the presence of a vortex flow field. It is shown that in certain configurations only 25 to 30 percent of the input energy is lost to the electrodes. It is also shown that vortex stabilization is not difficult to obtain in many cases at the flow rates used and that a careful starting procedure is effective in minimizing electrode damage.

  15. Numerical power balance and free energy loss analysis for solar cells including optical, thermodynamic, and electrical aspects

    SciTech Connect

    Greulich, Johannes Höffler, Hannes; Würfel, Uli; Rein, Stefan

    2013-11-28

    A method for analyzing the power losses of solar cells is presented, supplying a complete balance of the incident power, the optical, thermodynamic, and electrical power losses and the electrical output power. The involved quantities have the dimension of a power density (units: W/m{sup 2}), which permits their direct comparison. In order to avoid the over-representation of losses arising from the ultraviolet part of the solar spectrum, a method for the analysis of the electrical free energy losses is extended to include optical losses. This extended analysis does not focus on the incident solar power of, e.g., 1000 W/m{sup 2} and does not explicitly include the thermalization losses and losses due to the generation of entropy. Instead, the usable power, i.e., the free energy or electro-chemical potential of the electron-hole pairs is set as reference value, thereby, overcoming the ambiguities of the power balance. Both methods, the power balance and the free energy loss analysis, are carried out exemplarily for a monocrystalline p-type silicon metal wrap through solar cell with passivated emitter and rear (MWT-PERC) based on optical and electrical measurements and numerical modeling. The methods give interesting insights in photovoltaic (PV) energy conversion, provide quantitative analyses of all loss mechanisms, and supply the basis for the systematic technological improvement of the device.

  16. Vibrational spectroscopy and intramolecular energy transfer in isocyanic acid (HNCO)

    SciTech Connect

    Coffey, M.J.; Berghout, H.L.; Woods, E. III; Crim, F.F.

    1999-06-01

    Room temperature photoacoustic spectra in the region of the first through the fourth overtones (2{nu}{sub 1} to 5{nu}{sub 1}) and free-jet action spectra of the second through the fourth overtones (3{nu}{sub 1} to 5{nu}{sub 1}) of the N{endash}H stretching vibration permit analysis of the vibrational and rotational structure of HNCO. The analysis identifies the strong intramolecular couplings that control the early stages of intramolecular vibrational energy redistribution (IVR) and gives the interaction matrix elements between the zero-order N{endash}H stretching states and the other zero-order states with which they interact. The experimentally determined couplings and zero-order state separations are consistent with {ital ab initio} calculations of East, Johnson, and Allen [J. Chem. Phys. {bold 98}, 1299 (1993)], and comparison with the calculation identifies the coupled states and likely interactions. The states most strongly coupled to the pure N{endash}H stretching zero-order states are ones with a quantum of N{endash}H stretching excitation ({nu}{sub 1}) replaced by different combinations of N{endash}C{endash}O asymmetric or symmetric stretching excitation ({nu}{sub 2} or {nu}{sub 3}) and {ital trans}-bending excitation ({nu}{sub 4}). The two strongest couplings of the n{nu}{sub 1} state are to the states (n{minus}1){nu}{sub 1}+{nu}{sub 2}+{nu}{sub 4} and (n{minus}1){nu}{sub 1}+{nu}{sub 3}+2{nu}{sub 4}, and sequential couplings through a series of low order resonances potentially play a role. The analysis shows that if the pure N{endash}H stretch zero-order state were excited, energy would initially flow out of that mode into the strongly coupled mode in 100 fs to 700 fs, depending on the level of initial excitation. {copyright} {ital 1999 American Institute of Physics.}

  17. Radiation and ionization energy loss simulation for the GDH sum rule experiment in Hall-A at Jefferson Lab

    NASA Astrophysics Data System (ADS)

    Yan, Xin-Hu; Ye, Yun-Xiu; Chen, Jian-Ping; Lu, Hai-Jiang; Zhu, Peng-Jia; Jiang, Feng-Jian

    2015-07-01

    The radiation and ionization energy loss are presented for single arm Monte Carlo simulation for the GDH sum rule experiment in Hall-A at the Jefferson Lab. Radiation and ionization energy loss are discussed for 12C elastic scattering simulation. The relative momentum ratio \\frac{{Δ p}}{p} and 12C elastic cross section are compared without and with radiative energy loss and a reasonable shape is obtained by the simulation. The total energy loss distribution is obtained, showing a Landau shape for 12C elastic scattering. This simulation work will give good support for radiation correction analysis of the GDH sum rule experiment. Supported by National Natural Science Foundation of China (11135002, 11275083), US Department of Energy contract DE-AC05-84ER-40150 under which Jefferson Science Associates operates the Thomas Jefferson National Accelerator Facility and Natural Science Foundation of An'hui Educational Committee (KJ2012B179)

  18. Energy Dispersive X-Ray and Electrochemical Impedance Spectroscopies for Performance and Corrosion Analysis of PEMWEs

    NASA Astrophysics Data System (ADS)

    Steen, S. M., Iii; Zhang, F.-Y.

    2014-11-01

    Proton exchange membrane water electrolyzers (PEMWEs) are a promising energy storage technology due to their high efficiency, compact design, and ability to be used in a renewable energy system. Before they are able to make a large commercial impact, there are several hurdles facing the technology today. Two powerful techniques for both in-situ and ex- situ characterizations to improve upon their performance and better understand their corrosion are electrochemical impedance spectroscopy and energy dispersive x-ray spectroscopy, respectively. In this paper, the authors use both methods in order to characterize the anode gas diffusion layer (GDL) in a PEMWE cell and better understand the corrosion that occurs in the oxygen electrode during electrolysis.

  19. 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.

  20. 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

  1. Energy loss of ions in solids: Non-linear calculations for slow and swift ions

    NASA Astrophysics Data System (ADS)

    Arista, Néstor R.

    2002-10-01

    The historical approach to describe the energy loss of swift ions in solids is based on the Bohr, Bethe and Bloch theories. As is well known, the central parameter in these theories is the ratio η= Z1e2/ℏ v, whose value is generally used to delimit the ranges of applicability of the Bohr ( η>1) and Bethe ( η<1) theories. The transition between these regimes can be obtained by changing the ratio Z1/ v, although not by simply changing v. In fact, this scheme breaks down at low velocities, where quantum and non-linear effects arise. This domain is characterized by the strong oscillatory Z1 dependence of the stopping powers. This paper proposes a self-consistent non-linear approach to calculate the energy loss of heavy ions on a wide range of velocities. The model is based on the transport cross-section approach and on a previous extension of the Friedel sum rule for moving ions. The purpose of this study is to develop a non-linear stopping power evaluation method that could be applied at finite ion velocities, bridging the current gap between the low- and high-energy models.

  2. Cell type-specific transcriptomics of hypothalamic energy-sensing neuron responses to weight-loss

    PubMed Central

    Henry, Fredrick E; Sugino, Ken; Tozer, Adam; Branco, Tiago; Sternson, Scott M

    2015-01-01

    Molecular and cellular processes in neurons are critical for sensing and responding to energy deficit states, such as during weight-loss. Agouti related protein (AGRP)-expressing neurons are a key hypothalamic population that is activated during energy deficit and increases appetite and weight-gain. Cell type-specific transcriptomics can be used to identify pathways that counteract weight-loss, and here we report high-quality gene expression profiles of AGRP neurons from well-fed and food-deprived young adult mice. For comparison, we also analyzed Proopiomelanocortin (POMC)-expressing neurons, an intermingled population that suppresses appetite and body weight. We find that AGRP neurons are considerably more sensitive to energy deficit than POMC neurons. Furthermore, we identify cell type-specific pathways involving endoplasmic reticulum-stress, circadian signaling, ion channels, neuropeptides, and receptors. Combined with methods to validate and manipulate these pathways, this resource greatly expands molecular insight into neuronal regulation of body weight, and may be useful for devising therapeutic strategies for obesity and eating disorders. DOI: http://dx.doi.org/10.7554/eLife.09800.001 PMID:26329458

  3. FGF21, energy expenditure and weight loss – How much brown fat do you need?

    PubMed Central

    Straub, Leon; Wolfrum, Christian

    2015-01-01

    Background Fibroblast growth factor 21 (FGF21) belongs to the large family of fibroblast growth factors (FGFs). Even though FGF signaling has been mainly implicated in developmental processes, recent studies have demonstrated that FGF21 is an important regulator of whole body energy expenditure and metabolism, in obesity. Scope of review Given the fact that obesity has developed epidemic proportions, not just in industrialized countries, FGF21 has emerged as a novel therapeutic avenue to treat obesity as well as associated metabolic disorders. While the metabolic effects of FGF21 are undisputed, the mechanisms by which FGF21 regulate weight loss have not yet been fully resolved. Until recently it was believed that FGF21 induces brown fat activity, thereby enhancing energy expenditure, which concomitantly leads to weight loss. Novel studies have challenged this concept as they could demonstrate that a part of the FGF21 mediated effects are retained in a mouse model of impaired brown adipose tissue function. Major conclusions The review illustrates the recent advances in FGF21 research and discusses the role of FGF21 in the regulation of energy expenditure linked to brown fat activity. PMID:26413466

  4. Comparative Study of Hybrid Powertrains on Fuel Saving, Emissions, and Component Energy Loss in HD Trucks

    SciTech Connect

    Gao, Zhiming; Finney, Charles; Daw, Charles; LaClair, Tim J.; Smith, David

    2014-09-30

    We compared parallel and series hybrid powertrains on fuel economy, component energy loss, and emissions control in Class 8 trucks over both city and highway driving. A comprehensive set of component models describing battery energy, engine fuel efficiency, emissions control, and power demand interactions for heavy duty (HD) hybrids has been integrated with parallel and series hybrid Class 8 trucks in order to identify the technical barriers of these hybrid powertrain technologies. The results show that series hybrid is absolutely negative for fuel economy benefit of long-haul trucks due to an efficiency penalty associated with the dual-step conversions of energy (i.e. mechanical to electric to mechanical). The current parallel hybrid technology combined with 50% auxiliary load reduction could elevate 5-7% fuel economy of long-haul trucks, but a profound improvement of long-haul truck fuel economy requires additional innovative technologies for reducing aerodynamic drag and rolling resistance losses. The simulated emissions control indicates that hybrid trucks reduce more CO and HC emissions than conventional trucks. The simulated results further indicate that the catalyzed DPF played an important role in CO oxidations. Limited NH3 emissions could be slipped from the Urea SCR, but the average NH3 emissions are below 20 ppm. Meanwhile our estimations show 1.5-1.9% of equivalent fuel-cost penalty due to urea consumption in the simulated SCR cases.

  5. Heavy ion charge-state distribution effects on energy loss in plasmas

    NASA Astrophysics Data System (ADS)

    Barriga-Carrasco, Manuel D.

    2013-10-01

    According to dielectric formalism, the energy loss of the heavy ion depends on its velocity and its charge density. Also, it depends on the target through its dielectric function; here the random phase approximation is used because it correctly describes fully ionized plasmas at any degeneracy. On the other hand, the Brandt-Kitagawa (BK) model is employed to depict the projectile charge space distribution, and the stripping criterion of Kreussler is used to determine its mean charge state . This latter criterion implies that the mean charge state depends on the electron density and temperature of the plasma. Also, the initial charge state of the heavy ion is crucial for calculating inside the plasma. Comparing our models and estimations with experimental data, a very good agreement is found. It is noticed that the energy loss in plasmas is higher than that in the same cold gas cases, confirming the well-known enhanced plasma stopping (EPS). In this case, EPS is only due to the increase in projectile effective charge Qeff, which is obtained as the ratio between the energy loss of each heavy ion and that of the proton in the same plasma conditions. The ratio between the effective charges in plasmas and in cold gases is higher than 1, but it is not as high as thought in the past. Finally, another significant issue is that the calculated effective charge in plasmas Qeff is greater than the mean charge state , which is due to the incorporation of the BK charge distribution. When estimations are performed without this distribution, they do not fit well with experimental data.

  6. Energy loss, equilibration, and thermodynamics of a baryon rich strongly coupled quark-gluon plasma

    NASA Astrophysics Data System (ADS)

    Rougemont, Romulo; Ficnar, Andrej; Finazzo, Stefano I.; Noronha, Jorge

    2016-04-01

    Lattice data for the QCD equation of state and the baryon susceptibility near the crossover phase transition (at zero baryon density) are used to determine the input parameters of a 5-dimensional Einstein-Maxwell-Dilaton holographic model that provides a consistent holographic framework to study both equilibrium and out-of-equilibrium properties of a hot and baryon rich strongly coupled quark-gluon plasma (QGP). We compare our holographic equation of state computed at nonzero baryon chemical potential, μ B , with recent lattice calculations and find quantitative agreement for the pressure and the speed of sound for μ B ≤ 400 MeV. This holographic model is used to obtain holographic predictions for the temperature and μ B dependence of the drag force and the Langevin diffusion coefficients associated with heavy quark jet propagation as well as the jet quenching parameter q and the shooting string energy loss of light quarks in the baryon dense plasma. We find that the energy loss of heavy and light quarks generally displays a nontrivial, fast-varying behavior as a function of the temperature near the crossover. Moreover, energy loss is also found to generally increase due to nonzero baryon density effects even though this strongly coupled liquid cannot be described in terms of well defined quasiparticle excitations. Furthermore, to get a glimpse of how thermalization occurs in a hot and baryon dense QGP, we study how the lowest quasinormal mode of an external massless scalar disturbance in the bulk is affected by a nonzero baryon charge. We find that the equilibration time associated with the lowest quasinormal mode decreases in a dense medium.

  7. Extended fine structures in the electron energy loss spectrum of InAs

    NASA Technical Reports Server (NTRS)

    Schowengerdt, F. D.; Grunthaner, F. J.

    1988-01-01

    The possibility of using electron energy loss fine structure (EELFS) for the characterization of thin pseudomorphic quantum wells of InAs and GaAs(100) is investigated. It is shown that the EELFS technique can yield reliable radial distribution functions for bulk InAs, provided beam-induced sample degradation is controlled stringently. Additional improvements in the data collection procedures, including better control of the sample condition, are required as well as more detailed work on separating contributions from multiple edges in the data analysis.

  8. Parton Energy Loss Limits and Shadowing in Drell-Yan Dimuon Production

    SciTech Connect

    Isenhower, L.D.; Sadler, M.E.; Towell, R.S.; Willis, J.L.; Geesaman, D.F.; Kaufman, S.B.; Mueller, B.A.; Reimer, P.E.; Brown, C.N.; Cooper, W.E.; He, X.C.; Lee, W.M.; Petitt, G.; Kaplan, D.M.; Carey, T.A.; Garvey, G.T.; Hawker, E.A.; Leitch, M.J.; McGaughey, P.L.; Moss, J.M.; Peng, J.C.; Reimer, P.E.; Sondheim, W.E.; Towell, R.S.; Beddo, M.E.; Chang, T.H.; Papavassiliou, V.; Webb, J.C.; Stankus, P.W.; Young, G.R.; Vasiliev, M.A.; Gagliardi, C.A.; Hawker, E.A.; Tribble, R.E.; Koetke, D.D.

    1999-09-01

    A precise measurement of the ratios of the Drell-Yan cross section per nucleon for an 800 GeV/{ital c} proton beam incident on Be, Fe, and W targets is reported. The behavior of the Drell-Yan ratios at small target-parton momentum fraction is well described by an existing fit to the shadowing observed in deep-inelastic scattering. The cross-section ratios as a function of the incident-parton momentum fraction set tight limits on the energy loss of quarks passing through a cold nucleus. {copyright} {ital 1999} {ital The American Physical Society}

  9. Energy Loss of Heavy Quarks in a QGP with a Running Coupling Constant Approach

    NASA Astrophysics Data System (ADS)

    Gossiaux, P. B.; Aichelin, J.

    2009-11-01

    We show that the effective running coupling constant, α, and the effective regulator, κm˜D2, which we used recently to calculate the energy loss, dEdx, and the elliptic flow, v, of heavy quarks in an expanding quark gluon plasma plasma (QGP) [P. B. Gossiaux and J. Aichelin, Phys. Rev. C78, 014904 (2008), [arXiv:0802.2525], P. B. Gossiaux and J. Aichelin, J. Phys. G36 (2009) 064028, [arXiv:0901.2462], P. B. Gossiaux, R. Bierkandt and J. Aichelin, Phys. Rev. C79 (2009) 044906 [arXiv:0901.0946

  10. First principles study of electronic properties, interband transitions and electron energy loss of α-graphyne

    NASA Astrophysics Data System (ADS)

    Behzad, Somayeh

    2016-04-01

    The electronic and optical properties of α-graphyne sheet are investigated by using density functional theory. The results confirm that α-graphyne sheet is a zero-gap semimetal. The optical properties of the α-graphyne sheet such as dielectric function, refraction index, electron energy loss function, reflectivity, absorption coefficient and extinction index are calculated for both parallel and perpendicular electric field polarizations. The optical spectra are strongly anisotropic along these two polarizations. For (E ∥ x), absorption edge is at 0 eV, while there is no absorption below 8 eV for (E ∥ z).

  11. Collisionless high energy particle losses in optimized stellarators calculated in real-space coordinates

    SciTech Connect

    Nemov, V. V.; Kasilov, S. V.; Kernbichler, W.

    2014-06-15

    An approach for the direct computation of collisionless losses of high energy charged particles is developed for stellarator magnetic fields given in real space coordinates. With this approach, the corresponding computations can be performed for magnetic fields with three-dimensional inhomogeneities in the presence of stochastic regions as well as magnetic islands. A code, which is based on this approach, is applied to various stellarator configurations. It is found that the life time of fast particles obtained in real-space coordinates can be smaller than that obtained in magnetic coordinates.

  12. Strategies to increase vegetable or reduce energy and fat intake induce weight loss in adults.

    PubMed

    Tanumihardjo, Sherry A; Valentine, Ashley R; Zhang, Zhumin; Whigham, Leah D; Lai, HuiChuan J; Atkinson, Richard L

    2009-05-01

    For obese individuals seeking to optimize health and well-being, healthy dietary strategies are important. Vegetables and fruits contribute to a healthy diet, and increased consumption may cause weight reduction by displacing foods high in energy and fat. The objective of this study was to determine if advising high vegetable (8 servings) and moderate fruit (2-3 servings) consumption would result in weight reduction in obese individuals. We compared this to advising a more traditional strategy of reducing daily energy intake by 500 kcal (2.1 MJ)/d and limiting energy from fat to energy reduction diet), and the energy and fat reduction diet resulted in lower weight over time (P<0.0001, treatment effect). Total cholesterol and cholesterol:HDL decreased after 3 mo in both groups (Ploss at 3 mo, but only the group following the caloric and fat reduction advice maintained weight loss at the 12- and 18-mo follow-up assessments. Nonetheless, the group following the high vegetable advice did not regain weight above baseline. In conclusion, traditional messages to reduce calories and fat are important, and increasing vegetable intake can assist individuals to maintain weight. PMID:19234056

  13. Effects of intermittent compared to continuous energy restriction on short-term weight loss and long-term weight loss maintenance.

    PubMed

    Keogh, J B; Pedersen, E; Petersen, K S; Clifton, P M

    2014-06-01

    Effective strategies are needed to help individuals lose weight and maintain weight loss. The primary aim of this study was to investigate the effect of intermittent energy restriction (IER) compared to continuous energy restriction (CER) on weight loss after 8 weeks and weight loss maintenance after 12 months. Secondary aims were to determine changes in waist and hip measurements and diet quality. In a randomized parallel study, overweight and obese (body mass index [BMI] ≥ 27 kg m(-2)) women were stratified by age and BMI before randomization. Participants undertook an 8-week intensive period with weight, waist and hip circumference measured every 2 weeks, followed by 44 weeks of independent dieting. A food frequency questionnaire was completed at baseline and 12 months, from which diet quality was determined. Weight loss was not significantly different between the two groups at 8 weeks (-3.2 ± 2.1 kg CER, n = 20, -2.0 ± 1.9 kg IER, n = 25; P = 0.06) or at 12 months (-4.2 ± 5.6 kg CER, n = 17 -2.1 ± 3.8 kg IER, n = 19; P = 0.19). Weight loss between 8 and 52 weeks was -0.7 ± 49 kg CER vs. -1 ± 1.1 kg IER; P = 0.6. Waist and hip circumference decreased significantly with time (P < 0.01), with no difference between groups. There was an increase in the Healthy Eating Index at 12 months in the CER compared with the IER group (CER 8.4 ± 9.1 vs. IER -0.3 ± 8.4, P = 0.006). This study indicates that intermittent dieting was as effective as continuous dieting over 8 weeks and for weight loss maintenance at 12 months. This may be useful for individuals who find CER too difficult to maintain. PMID:25826770

  14. Isoconversion effective activation energy profiles by variable temperature diffuse reflection infrared spectroscopy.

    PubMed

    White, Daniel R; White, Robert L

    2008-01-01

    Thermal process characterization based on calculating effective activation energies from variable temperature diffuse reflection infrared spectroscopy (VT-DRIFTS) measurements is demonstrated. Experimental factors that affect the accuracies of activation energy values are outlined. Infrared radiation scattering efficiency, thermal conductivity, and inertness towards chemical reactions are factors that should be considered when selecting an appropriate diluent for preparing samples. The Kubelka-Munk representation is superior to apparent absorbance when baseline variations in spectra measured at different temperatures can be minimized. Variable-temperature infrared spectral features, such as integrated absorption band area, can be used to compute isoconversion effective activation energies, provided that measured quantities are proportional to species concentrations. PMID:18230216

  15. Implications of Postharvest Food Loss/Waste Prevention to Energy and Resources Conservation

    NASA Astrophysics Data System (ADS)

    Cai, X.; Shafiee-Jood, M.

    2015-12-01

    World's growing demand for food is driven by population and income growth, dietary changes, and the ever-increasing competition between food, feed and bioenergy challenges food security; meanwhile agricultural expansion and intensification threats the environment by the various detrimental impacts. Researchers have attempted to explore strategies to overcome this grand challenge. One of the promising solutions that have attracted considerable attention recently is to increase the efficiency of food supply chain by reducing food loss and waste (FLW). According to recent studies conducted by Food and Agriculture Organization (FAO), United Nation, almost one third of the food produced for human consumption globally is lost or wasted along the food supply chain. This amount of food discarded manifests a missing, yet potential, opportunity to sustainably enhance both food security and environmental sustainability. However, implementing the strategies and technologies for tackling FLW does not come up as an easy solution since it requires economic incentives, benefit and cost analysis, infrastructure development, and appropriate market mechanism. In this presentation I will provide a synthesis of knowledge on the implications of postharvest food loss/waste prevention to energy and resource conservation, environmental protection, as well as food security. I will also discuss how traditional civil and environmental engineering can contribute to the reduction of postharvest food loss, an important issue of sustainable agriculture.

  16. Solid-state effects and atomiclike effects on shallow inner-shell-electron energy-loss spectra of a cation p or d hole in sulfides

    NASA Astrophysics Data System (ADS)

    Ohno, Youichi

    1994-03-01

    Inner-shell-electron energy-loss spectroscopy studies have been done for the systems in which a shallow p or d core hole exists in the final state of a cation. Optically allowed and forbidden transitions have been distinguished from spectral variations due to the breakdown of dipole selection rules. The Ti and V M2,3 spectra and the Zr, Nb, and Mo M4,5 spectra in layered transition-metal disulfides and related misfit-layer compounds are well explained in terms of the energy-band structures. The overall structures of the Pb and Bi O4,5 spectra are understood within the atomic model containing j-j coupling. The Sn N4,5 spectra in SnS and SnS2 are intermediate between them. A reasonable explanation is given by both the atomic model and the band-structure model.

  17. Energy-loss cross sections for inclusive charge-exchange reactions at intermediate energies

    NASA Technical Reports Server (NTRS)

    Cucinotta, Francis A.; Townsend, Lawrence W.; Dubey, Rajendra R.

    1993-01-01

    Charge-exchange reactions for scattering to the continuum are considered in a high-energy multiple scattering model. Calculations for (p,n) and (He-3,H-3) reactions are made and compared with experimental results for C-12, O-16, and Al-27 targets. Coherent effects are shown to lead to an important role for inelastic multiple scattering terms when light projectiles are considered.

  18. Energy Loss of Heavy Quarks—A Signal of Plasma Properties

    NASA Astrophysics Data System (ADS)

    Aichelin, J.

    The possible observables for studying the properties of a plasma of quarks and gluons (QGP), which is presumably created in ultrarelativistic heavy-ion collisions, are discussed. While the light mesons do not contain the desired information about the QGP phase due to the strong final hadronic interaction, the `heavy' mesons, i.e. those containing a c- or b- quark, are more useful. We demonstrate that our recent pQCD based approach for the energy loss of heavy quarks in a QGP combined with hydrodynamical model of Kolb and Heinz for the expansion of the plasma can successfully describe the variety of experimental data—as the transverse momentum spectra, R_{AA}, and the elliptic flow v_2 of heavy quarks—from RHIC to LHC energies.

  19. Laser-beam zooming to mitigate crossed-beam energy losses in direct-drive implosions.

    PubMed

    Igumenshchev, I V; Froula, D H; Edgell, D H; Goncharov, V N; Kessler, T J; Marshall, F J; McCrory, R L; McKenty, P W; Meyerhofer, D D; Michel, D T; Sangster, T C; Seka, W; Skupsky, S

    2013-04-01

    Spherically symmetric direct-drive-ignition designs driven by laser beams with a focal-spot size nearly equal to the target diameter suffer from energy losses due to crossed-beam energy transfer (CBET). Significant reduction of CBET and improvements in implosion hydrodynamic efficiency can be achieved by reducing the beam diameter. Narrow beams increase low-mode perturbations of the targets because of decreased illumination uniformity that degrades implosion performance. Initiating an implosion with nominal beams (equal in size to the target diameter) and reducing the beam diameter by ∼ 30%-40% after developing a sufficiently thick target corona, which smooths the perturbations, mitigate CBET while maintaining low-mode target uniformity in ignition designs with a fusion gain ≫ 1. PMID:25166997

  20. Energy loss of argon in a laser-generated carbon plasma

    SciTech Connect

    Frank, A.; Harres, K.; Hoffmann, D. H. H.; Knobloch-Maas, R.; Nuernberg, F.; Pelka, A.; Schaumann, G.; Schoekel, A.; Schollmeier, M.; Schumacher, D.; Schuetrumpf, J.; Roth, M.; Blazevic, A.; Hessling, T.; Grande, P. L.; Kuznetsov, P. G.; Vatulin, V. V.; Vinokurov, O. A.; Schiwietz, G.

    2010-02-15

    The experimental data presented in this paper address the energy loss determination for argon at 4 MeV/u projectile energy in laser-generated carbon plasma covering a huge parameter range in density and temperature. Furthermore, a consistent theoretical description of the projectile charge state evolution via a Monte Carlo code is combined with an improved version of the CasP code that allows us to calculate the contributions to the stopping power of bound and free electrons for each projectile charge state. This approach gets rid of any effective charge description of the stopping power. Comparison of experimental data and theoretical results allows us to judge the influence of different plasma parameters.

  1. Charge-state-dependent energy loss of slow ions. II. Statistical atom model

    NASA Astrophysics Data System (ADS)

    Wilhelm, Richard A.; Möller, Wolfhard

    2016-05-01

    A model for charge-dependent energy loss of slow ions is developed based on the Thomas-Fermi statistical model of atoms. Using a modified electrostatic potential which takes the ionic charge into account, nuclear and electronic energy transfers are calculated, the latter by an extension of the Firsov model. To evaluate the importance of multiple collisions even in nanometer-thick target materials we use the charge-state-dependent potentials in a Monte Carlo simulation in the binary collision approximation and compare the results to experiment. The Monte Carlo results reproduce the incident charge-state dependence of measured data well [see R. A. Wilhelm et al., Phys. Rev. A 93, 052708 (2016), 10.1103/PhysRevA.93.052708], even though the experimentally observed charge exchange dependence is not included in the model.

  2. Optimal heading change with minimum energy loss for a hypersonic gliding vehicle

    NASA Technical Reports Server (NTRS)

    Calise, Anthony J.; Bae, Gyoung H.

    1987-01-01

    A three state model is presented for analyzing the problem of optimal changes in heading with minimum energy loss for a hypersonic gliding vehicle. A further model order reduction to a single state model is examined using singular perturbation theory. The optimal solution for the reduced problem defines an optimal altitude profile dependent on the current energy of the vehicle, and the corresponding optimal lift and bank angle. A separate boundary layer analysis, based on an expansion of the necessary conditions about the reduced solution, is used to account for altitude and flight path angle dynamics and to derive a guidance law in feedback form. The guidance law is evaluated for a hypothetical vehicle.

  3. A Three Dimensional Calculation of Electron Energy Loss in a Variable Parameter Free-Electron Laser

    SciTech Connect

    Luccio, A.; Pellegrini, C.

    1980-03-01

    A single-pass free-electron laser (FEL) using a wiggler magnet with either the period, and/or the magnetic field, varying along the magnet axis has been proposed. The main advantage of this system over a conventional free-electron laser, having a constant period and magnetic field wiggler, is in the higher efficiency of the energy transfer from the electron beam to the laser radiation field. This efficiency, which is of the order of 1% in a conventional FEL, can be of the order of 30% in a variable wiggler FEL. The theory of the variable wiggler FEL is based on a one dimensional model, in which the electron motion transverse to the laser axis is assumed to be given and only the motion parallel to the axis is studied. In this paper, the effect on the laser efficiency of the electron transverse motion is studied and the electron energy loss is evaluated for a beam having a spread in angle and in the transverse position at the wiggler entrance. The complete three dimensional equations of motion for an electron interacting with the laser field and the wiggler field are integrated numerically. Only the case of a small gain regime, assuming that the laser field intensity remains constant, is considered. Also, this study is limited to the case of a helical wiggler. The results are compared with the one dimensional model. The effect of the initial position and angular spread can, to a good approximation, be considered equivalent to an increase in the energy spread. The limits for this increased energy spread that must not be exceeded in order to avoid a loss in efficiency are nearly the same as in the one dimensional model.

  4. Compositions and chemical bonding in ceramics by quantitative electron energy-loss spectrometry

    SciTech Connect

    Bentley, J.; Horton, L.L.; McHargue, C.J.; McKernan, S.; Carter, C.B.; Revcolevschi, A.; Tanaka, S.; Davis, R.F.

    1993-12-31

    Quantitative electron energy-loss spectrometry was applied to a range of ceramic materials at a spatial resolution of <5 nm. Analysis of Fe L{sub 23} white lines indicated a low-spin state with a charge transfer of {approximately}1.5 electrons/atom onto the Fe atoms implanted into (amorphized) silicon carbide. Gradients of 2 to 5% in the Co:O stoichiometry were measured across 100-nm-thick Co{sub 3}O{sub 4} layers in an oxidized directionally solidified CoO-ZrO{sub 2} eutectic, with the highest O levels near the ZrO{sub 2}. The energy-loss near-edge structures were dramatically different for the two cobalt oxides; those for CO{sub 3}O{sub 4} have been incorrectly ascribed to CoO in the published literature. Kinetically stabilized solid solubility occurred in an AlN-SiC film grown by low-temperature molecular beam epitaxy (MBE) on {alpha}(6H)-SiC, and no detectable interdiffusion occurred in couples of MBE-grown AlN on SiC following annealing at up to 1750C. In diffusion couples of polycrystalline AlN on SiC, interfacial 8H sialon (aluminum oxy-nitride) and pockets of Si{sub 3}N{sub 4}-rich {beta}{prime} sialon in the SiC were detected.

  5. Energy loss, hadronization, and hadronic interactions of heavy flavors in relativistic heavy-ion collisions

    NASA Astrophysics Data System (ADS)

    Cao, Shanshan; Qin, Guang-You; Bass, Steffen A.

    2015-08-01

    We construct a theoretical framework to describe the evolution of heavy flavors produced in relativistic heavy-ion collisions. The in-medium energy loss of heavy quarks is described using our modified Langevin equation that incorporates both quasielastic scatterings and the medium-induced gluon radiation. The space-time profiles of the fireball are described by a (2+1)-dimensional hydrodynamics simulation. A hybrid model of fragmentation and coalescence is utilized for heavy quark hadronization, after which the produced heavy mesons together with the soft hadrons produced from the bulk quark-gluon plasma (QGP) are fed into the hadron cascade ultrarelativistic quantum molecular dynamics (UrQMD) model to simulate the subsequent hadronic interactions. We find that the medium-induced gluon radiation contributes significantly to heavy quark energy loss at high pT; heavy-light quark coalescence enhances heavy meson production at intermediate pT; and scatterings inside the hadron gas further suppress the D meson RAA at large pT and enhance its v2. Our calculations provide good descriptions of heavy meson suppression and elliptic flow observed at both the Large Hadron Collider and the Relativistic Heavy-Ion Collider.

  6. Phenotypic vulnerability of energy balance responses to sleep loss in healthy adults

    PubMed Central

    Spaeth, Andrea M.; Dinges, David F.; Goel, Namni

    2015-01-01

    Short sleep duration is a risk factor for increased hunger and caloric intake, late-night eating, attenuated fat loss when dieting, and for weight gain and obesity. It is unknown whether altered energy-balance responses to sleep loss are stable (phenotypic) over time, and the extent to which individuals differ in vulnerability to such responses. Healthy adults experienced two laboratory exposures to sleep restriction separated by 60–2132 days. Caloric intake, meal timing and weight were objectively measured. Although there were substantial phenotypic differences among participants in weight gain, increased caloric intake, and late-night eating and fat intake, responses within participants showed stability across sleep restriction exposures. Weight change was consistent in both normal-weight and overweight adults. Weight change and increased caloric intake were more stable in men whereas late-night eating was consistent in both genders. This is the first evidence of phenotypic differential vulnerability and trait-like stability of energy balance responses to repeated sleep restriction, underscoring the need for biomarkers and countermeasures to predict and mitigate this vulnerability. PMID:26446681

  7. Eikonal approximation in the theory of energy loss by fast charged particles

    NASA Astrophysics Data System (ADS)

    Matveev, V. I.; Makarov, D. N.; Gusarevich, E. S.

    2011-05-01

    Energy losses in fast charged particles as a result of collisions with atoms are considered in the eikonal approximation. It is shown that the nonperturbative contribution to effective stopping in the range of intermediate impact parameters (comparable with the characteristic sizes of the electron shells of the target atoms) may turn out to be significant as compared to shell corrections to the Bethe-Bloch formula calculated in perturbation theory. The simplifying assumptions are formulated under which the Bethe-Bloch formula can be derived in the eikonal approximation. It is shown that the allowance for nonperturbative effects may lead to considerable (up to 50%) corrections to the Bethe-Bloch formula. The applicability range for the Bethe-Bloch formula is analyzed. It is concluded that calculation of the energy loss in the eikonal approximation (in the range of impact parameters for which the Bethe-Bloch formula is normally used) is much more advantageous than analysis based on the Bethe-Bloch formula and its modifications because not only the Bloch correction is included in the former calculations, the range of intermediate impact parameters is also taken into account nonperturbatively; in addition, direct generalization to the cases of collisions of complex projectiles and targets is possible in this case.

  8. Comparative Study of Hybrid Powertrains on Fuel Saving, Emissions, and Component Energy Loss in HD Trucks

    DOE PAGESBeta

    Gao, Zhiming; Finney, Charles; Daw, Charles; LaClair, Tim J.; Smith, David

    2014-09-30

    We compared parallel and series hybrid powertrains on fuel economy, component energy loss, and emissions control in Class 8 trucks over both city and highway driving. A comprehensive set of component models describing battery energy, engine fuel efficiency, emissions control, and power demand interactions for heavy duty (HD) hybrids has been integrated with parallel and series hybrid Class 8 trucks in order to identify the technical barriers of these hybrid powertrain technologies. The results show that series hybrid is absolutely negative for fuel economy benefit of long-haul trucks due to an efficiency penalty associated with the dual-step conversions of energymore » (i.e. mechanical to electric to mechanical). The current parallel hybrid technology combined with 50% auxiliary load reduction could elevate 5-7% fuel economy of long-haul trucks, but a profound improvement of long-haul truck fuel economy requires additional innovative technologies for reducing aerodynamic drag and rolling resistance losses. The simulated emissions control indicates that hybrid trucks reduce more CO and HC emissions than conventional trucks. The simulated results further indicate that the catalyzed DPF played an important role in CO oxidations. Limited NH3 emissions could be slipped from the Urea SCR, but the average NH3 emissions are below 20 ppm. Meanwhile our estimations show 1.5-1.9% of equivalent fuel-cost penalty due to urea consumption in the simulated SCR cases.« less

  9. Sensitivity of the jet quenching observables to the temperature dependence of the energy loss

    SciTech Connect

    Scardina, Francesco; Di Toro, Massimo; Greco, Vincenzo

    2010-11-15

    The quenching of minijets (particles with p{sub T}>>T,{Lambda}{sub QCD}) in ultrarelativistic heavy-ion collisions has been one of the main predictions and discoveries at the BNL Relativistic Heavy Ion Collider. We analyze the correlation between different observables like the nuclear modification factor R{sub AA}(p{sub T}), the elliptic flow, and the ratio of quark to gluon suppressions. We show that the temperature (or entropy density) dependence of the in-medium energy loss strongly affects the relation among these observables. In particular, the large elliptic flow and the nearly equal R{sub AA}(p{sub T}) of quarks and gluons can be accounted for only if the energy loss occurs mainly around T{sub c} and the q{r_reversible}g conversion is significant. The use of an equation of state fitted to lattice QCD calculations, slowing down the cooling as T{yields}T{sub c}, seems to contribute to both the enhancement of v{sub 2} and the efficiency of the conversion mechanism.

  10. Radiative loss and charge exchange in low energy Na - Ca+ collisions

    NASA Astrophysics Data System (ADS)

    McLaughlin, B. M.; McAlpine, K.; McCann, J. F.; Pattillo, R.; Stancil, P. C.; Forrey, R. C.; Babb, J. F.

    2016-05-01

    Experiments on radiative loss and capture are currently being performed at the University of Connecticut. In response to this experimental effort we have performed detailed calculations for a variety of loss and capture processes. Several low lying states of the NaCa+ cation are used with the accurate potentials energy curves, transition dipole moments and non-adiabatic coupling matrix elements between the states, obtained at the MRCI+Q level of approximation with the MOLPRO suite of quantum chemistry codes. Cross sections and rate coefficients are calculated for radiative charge transfer (RCX), radiative association (RA) and charge exchange in a fully quantum molecular close-coupling (MOCC) approximation at the higher energies. We use a variety of approaches, the optical potential method, semi-classical and MOCC methods to compare and contrast approximations. In addition a kinetic theory recently applied to SiO is utilized which illustrates the dramatic impact resonances have on the radiative association rates. Supported by NASA and HLRS at Stuttgart University.

  11. Phenotypic vulnerability of energy balance responses to sleep loss in healthy adults.

    PubMed

    Spaeth, Andrea M; Dinges, David F; Goel, Namni

    2015-01-01

    Short sleep duration is a risk factor for increased hunger and caloric intake, late-night eating, attenuated fat loss when dieting, and for weight gain and obesity. It is unknown whether altered energy-balance responses to sleep loss are stable (phenotypic) over time, and the extent to which individuals differ in vulnerability to such responses. Healthy adults experienced two laboratory exposures to sleep restriction separated by 60-2132 days. Caloric intake, meal timing and weight were objectively measured. Although there were substantial phenotypic differences among participants in weight gain, increased caloric intake, and late-night eating and fat intake, responses within participants showed stability across sleep restriction exposures. Weight change was consistent in both normal-weight and overweight adults. Weight change and increased caloric intake were more stable in men whereas late-night eating was consistent in both genders. This is the first evidence of phenotypic differential vulnerability and trait-like stability of energy balance responses to repeated sleep restriction, underscoring the need for biomarkers and countermeasures to predict and mitigate this vulnerability. PMID:26446681

  12. Modal analysis of the energy loss for an accelerated electron beam passing through a laser-driven RF gun

    NASA Astrophysics Data System (ADS)

    Salah, W.

    2002-06-01

    The energy loss for an accelerated electron beam passing through a laser-driven RF gun has been studied. An analytical formula of the energy loss has been obtained using the time-dependent resonant modes of a cylindrical "pill-box" cavity. As an approximation, this formalism assumes a rigid beam pulse so the change of pulse shape dealing with space-charge force and wake field force is ignored.

  13. Training response inhibition to food is associated with weight loss and reduced energy intake

    PubMed Central

    Lawrence, Natalia S.; O'Sullivan, Jamie; Parslow, David; Javaid, Mahmood; Adams, Rachel C.; Chambers, Christopher D.; Kos, Katarina; Verbruggen, Frederick

    2015-01-01

    The majority of adults in the UK and US are overweight or obese due to multiple factors including excess energy intake. Training people to inhibit simple motor responses (key presses) to high-energy density food pictures reduces intake in laboratory studies. We examined whether online response inhibition training reduced real-world food consumption and weight in a community sample of adults who were predominantly overweight or obese (N = 83). Participants were allocated in a randomised, double-blind design to receive four 10-min sessions of either active or control go/no-go training in which either high-energy density snack foods (active) or non-food stimuli (control) were associated with no-go signals. Participants' weight, energy intake (calculated from 24-h food diaries), daily snacking frequency and subjective food evaluations were measured for one week pre- and post-intervention. Participants also provided self-reported weight and monthly snacking frequency at pre-intervention screening, and one month and six months after completing the study. Participants in the active relative to control condition showed significant weight loss, reductions in daily energy intake and a reduction in rated liking of high-energy density (no-go) foods from the pre-to post-intervention week. There were no changes in self-reported daily snacking frequency. At longer-term follow-up, the active group showed significant reductions in self-reported weight at six months, whilst both groups reported significantly less snacking at one- and six-months. Excellent rates of adherence (97%) and positive feedback about the training suggest that this intervention is acceptable and has the potential to improve public health by reducing energy intake and overweight. PMID:26122756

  14. Note: Electron energy spectroscopy mapping of surface with scanning tunneling microscope.

    PubMed

    Li, Meng; Xu, Chunkai; Zhang, Panke; Li, Zhean; Chen, Xiangjun

    2016-08-01

    We report a novel scanning probe electron energy spectrometer (SPEES) which combines a double toroidal analyzer with a scanning tunneling microscope to achieve both topography imaging and electron energy spectroscopy mapping of surface in situ. The spatial resolution of spectroscopy mapping is determined to be better than 0.7 ± 0.2 μm at a tip sample distance of 7 μm. Meanwhile, the size of the field emission electron beam spot on the surface is also measured, and is about 3.6 ± 0.8 μm in diameter. This unambiguously demonstrates that the spatial resolution of SPEES technique can be much better than the size of the incident electron beam. PMID:27587179

  15. A tunable low-energy photon source for high-resolution angle-resolved photoemission spectroscopy

    SciTech Connect

    Harter, John W.; Monkman, Eric J.; Shai, Daniel E.; Nie Yuefeng; Uchida, Masaki; Burganov, Bulat; Chatterjee, Shouvik; King, Philip D. C.; Shen, Kyle M.

    2012-11-15

    We describe a tunable low-energy photon source consisting of a laser-driven xenon plasma lamp coupled to a Czerny-Turner monochromator. The combined tunability, brightness, and narrow spectral bandwidth make this light source useful in laboratory-based high-resolution photoemission spectroscopy experiments. The source supplies photons with energies up to {approx}7 eV, delivering under typical conditions >10{sup 12} ph/s within a 10 meV spectral bandwidth, which is comparable to helium plasma lamps and many synchrotron beamlines. We first describe the lamp and monochromator system and then characterize its output, with attention to those parameters which are of interest for photoemission experiments. Finally, we present angle-resolved photoemission spectroscopy data using the light source and compare its performance to a conventional helium plasma lamp.

  16. Note: Electron energy spectroscopy mapping of surface with scanning tunneling microscope

    NASA Astrophysics Data System (ADS)

    Li, Meng; Xu, Chunkai; Zhang, Panke; Li, Zhean; Chen, Xiangjun

    2016-08-01

    We report a novel scanning probe electron energy spectrometer (SPEES) which combines a double toroidal analyzer with a scanning tunneling microscope to achieve both topography imaging and electron energy spectroscopy mapping of surface in situ. The spatial resolution of spectroscopy mapping is determined to be better than 0.7 ± 0.2 μm at a tip sample distance of 7 μm. Meanwhile, the size of the field emission electron beam spot on the surface is also measured, and is about 3.6 ± 0.8 μm in diameter. This unambiguously demonstrates that the spatial resolution of SPEES technique can be much better than the size of the incident electron beam.

  17. Predicting successful long-term weight loss from short-term weight-loss outcomes: new insights from a dynamic energy balance model (the POUNDS Lost study)123

    PubMed Central

    Ivanescu, Andrada E; Martin, Corby K; Heymsfield, Steven B; Marshall, Kaitlyn; Bodrato, Victoria E; Williamson, Donald A; Anton, Stephen D; Sacks, Frank M; Ryan, Donna; Bray, George A

    2015-01-01

    Background: Currently, early weight-loss predictions of long-term weight-loss success rely on fixed percent-weight-loss thresholds. Objective: The objective was to develop thresholds during the first 3 mo of intervention that include the influence of age, sex, baseline weight, percent weight loss, and deviations from expected weight to predict whether a participant is likely to lose 5% or more body weight by year 1. Design: Data consisting of month 1, 2, 3, and 12 treatment weights were obtained from the 2-y Preventing Obesity Using Novel Dietary Strategies (POUNDS Lost) intervention. Logistic regression models that included covariates of age, height, sex, baseline weight, target energy intake, percent weight loss, and deviation of actual weight from expected were developed for months 1, 2, and 3 that predicted the probability of losing <5% of body weight in 1 y. Receiver operating characteristic (ROC) curves, area under the curve (AUC), and thresholds were calculated for each model. The AUC statistic quantified the ROC curve’s capacity to classify participants likely to lose <5% of their body weight at the end of 1 y. The models yielding the highest AUC were retained as optimal. For comparison with current practice, ROC curves relying solely on percent weight loss were also calculated. Results: Optimal models for months 1, 2, and 3 yielded ROC curves with AUCs of 0.68 (95% CI: 0.63, 0.74), 0.75 (95% CI: 0.71, 0.81), and 0.79 (95% CI: 0.74, 0.84), respectively. Percent weight loss alone was not better at identifying true positives than random chance (AUC ≤0.50). Conclusions: The newly derived models provide a personalized prediction of long-term success from early weight-loss variables. The predictions improve on existing fixed percent-weight-loss thresholds. Future research is needed to explore model application for informing treatment approaches during early intervention. The POUNDS Lost study was registered at clinicaltrials.gov as NCT00072995. PMID:25733628

  18. FAR-INFRARED SPECTROSCOPY OF CATIONIC POLYCYCLIC AROMATIC HYDROCARBONS: ZERO KINETIC ENERGY PHOTOELECTRON SPECTROSCOPY OF PENTACENE VAPORIZED FROM LASER DESORPTION

    SciTech Connect

    Zhang Jie; Han Fangyuan; Pei Linsen; Kong Wei; Li Aigen

    2010-05-20

    The distinctive set of infrared (IR) emission bands at 3.3, 6.2, 7.7, 8.6, and 11.3 {mu}m are ubiquitously seen in a wide variety of astrophysical environments. They are generally attributed to polycyclic aromatic hydrocarbon (PAH) molecules. However, not a single PAH species has yet been identified in space, as the mid-IR vibrational bands are mostly representative of functional groups and thus do not allow one to fingerprint individual PAH molecules. In contrast, the far-IR (FIR) bands are sensitive to the skeletal characteristics of a molecule, hence they are important for chemical identification of unknown species. With an aim to offer laboratory astrophysical data for the Herschel Space Observatory, Stratospheric Observatory for Infrared Astronomy, and similar future space missions, in this work we report neutral and cation FIR spectroscopy of pentacene (C{sub 22}H{sub 14}), a five-ring PAH molecule. We report three IR active modes of cationic pentacene at 53.3, 84.8, and 266 {mu}m that may be detectable by space missions such as the SAFARI instrument on board SPICA. In the experiment, pentacene is vaporized from a laser desorption source and cooled by a supersonic argon beam. We have obtained results from two-color resonantly enhanced multiphoton ionization and two-color zero kinetic energy photoelectron (ZEKE) spectroscopy. Several skeletal vibrational modes of the first electronically excited state of the neutral species and those of the cation are assigned, with the aid of ab initio and density functional calculations. Although ZEKE is governed by the Franck-Condon principle different from direct IR absorption or emission, vibronic coupling in the long ribbon-like molecule results in the observation of a few IR active modes. Within the experimental resolution of {approx}7 cm{sup -1}, the frequency values from our calculation agree with the experiment for the cation, but differ for the electronically excited intermediate state. Consequently, modeling of the

  19. Energy loss of tens keV charged particles traveling in the hot dense carbon plasma

    NASA Astrophysics Data System (ADS)

    Fu, ZhenGuo; Wang, ZhiGang; He, Bin; Li, DaFang; Zhang, Ping

    2016-08-01

    The energy loss of charged particles, including electrons, protons, and α-particles with tens keV initial energy E 0, traveling in the hot dense carbon (C) plasma for densities from 2.281 to 22.81 g/cm3 and temperatures from 400 to 1500 eV is systematically and quantitatively studied by using the dimensional continuation method. The behaviors of different charged particles are readily distinguishable from each other. Firstly, because an ion is thousands times heavier than an electron, the penetration distance of the electron is much longer than that of proton and α-particle traveling in the plasma. Secondly, most energy of electron projectile with E 0 < 100 keV deposits into the electron species of C plasma, while for the cases of proton and α-particle with E 0 < 100 keV, about more than half energy transfers into the ion species of C plasma. A simple decreasing law of the penetration distance as a function of the plasma density is fitted, and different behaviors of each projectile particle can be clearly found from the fitted data. We believe that with the advanced progress of the present experimental technology, the findings shown here could be confirmed in ion-stopping experiments in the near future.

  20. Temperature-resolution anomalies in the reconstruction of time dynamics from energy-loss experiments

    NASA Astrophysics Data System (ADS)

    Kogar, Anshul; Vig, Sean; Gan, Yu; Abbamonte, Peter

    2014-06-01

    Inelastic scattering techniques provide a powerful approach to studying electron and nuclear dynamics, via reconstruction of a propagator that quantifies the time evolution of a system. There is now growing interest in applying such methods to very low energy excitations, such as lattice vibrations, but in this limit the cross section is no longer proportional to a propagator. Significant deviations occur due to the finite temperature Bose statistics of the excitations. Here we consider this issue in the context of high-resolution electron energy-loss experiments on the copper-oxide superconductor Bi2Sr2CaCu2O8. We find that simple division of a Bose factor yields an accurate propagator on energy scales greater than the resolution width. However, at low energy scales, the effects of resolution and finite temperature conspire to create anomalies in the dynamics at long times. We compare two practical ways for dealing with such anomalies, and discuss the range of validity of the technique in light of this comparison.

  1. Low-energy electro- and photo-emission spectroscopy of GaN materials and devices

    SciTech Connect

    Piccardo, Marco; Weisbuch, Claude; Iveland, Justin; Nakamura, Shuji; Speck, James S.; Martinelli, Lucio Peretti, Jacques; Choi, Joo Won

    2015-03-21

    In hot-electron semiconductor devices, carrier transport extends over a wide range of conduction states, which often includes multiple satellite valleys. Electrical measurements can hardly give access to the transport processes over such a wide range without resorting to models and simulations. An alternative experimental approach however exists which is based on low-energy electron spectroscopy and provides, in a number of cases, very direct and selective information on hot-electron transport mechanisms. Recent results obtained in GaN crystals and devices by electron emission spectroscopy are discussed. Using near-band-gap photoemission, the energy position of the first satellite valley in wurtzite GaN is directly determined. By electro-emission spectroscopy, we show that the measurement of the electron spectrum emitted from a GaN p-n junction and InGaN/GaN light-emitting diodes (LEDs) under electrical injection of carriers provides a direct observation of transport processes in these devices. In particular, at high injected current density, high-energy features appear in the electro-emission spectrum of the LEDs showing that Auger electrons are being generated in the active region. These measurements allow us identifying the microscopic mechanism responsible for droop which represents a major hurdle for widespread adoption of solid-state lighting.

  2. Recovery effects due to the interaction between nuclear and electronic energy losses in SiC irradiated with a dual-ion beam

    NASA Astrophysics Data System (ADS)

    Thomé, Lionel; Velisa, Gihan; Miro, Sandrine; Debelle, Aurélien; Garrido, Frédérico; Sattonnay, Gaël; Mylonas, Stamatis; Trocellier, Patrick; Serruys, Yves

    2015-03-01

    Single and dual-beam ion irradiations of silicon carbide (SiC) were performed to study possible Synergetic effects between Nuclear (Sn) and Electronic (Se) Energy Losses. Results obtained combining Rutherford backscattering in channeling conditions, Raman spectroscopy, and transmission electron microscopy techniques show that dual-beam irradiation of SiC induces a dramatic change in the final sample microstructure with a substantial decrease of radiation damage as compared to single-beam irradiation. Actually, a defective layer containing dislocations is formed upon dual-beam irradiation (Sn&Se), whereas single low-energy irradiation (Sn alone) or even sequential (Sn + Se) irradiations lead to full amorphization. The healing process is ascribed to the electronic excitation arising from the electronic energy loss of swift ions. These results shed new light on the long-standing puzzling problem of the existence of a possible synergy between Sn and Se in ion-irradiation experiments. This work is interesting for both fundamental understanding of the ion-solid interactions and technological applications in the nuclear industry where recovery Sn/Se effects may preserve the integrity of nuclear devices.

  3. Microscopic energy transfer spectroscopy to determine mitochondrial malfunction in human myotubes

    NASA Astrophysics Data System (ADS)

    Gschwend, Michael H.; Strauss, Wolfgang S. L.; Brinkmeier, H.; Ruedel, R.; Steiner, Rudolf W.; Schneckenburger, Herbert

    1996-12-01

    A microscopic equipment is reported for examination of cellular autofluorescence and determination of energy transfer in vitro, which is proposed to be an appropriate tool to investigate mitochondrial malfunction. The method includes fluorescence microscopy combined with time-gated (nanosecond) fluorescence emission spectroscopy and is presently used to study mitochondrial metabolism of human myotube primary cultures Enzyme complexes of the respiratory chain, located at the inner mitochondrial membrane, were inhibited by various drugs, and fluorescence of the mitochondrial coenzyme nicotinamide adenine dinucleotide (NADH) as well as of the mitochondrial marker rhodamine 123 (R123) was examined. After inhibition of enzyme complex I (NADH-coenzyme Q reductase) by rotenone or enzyme complex III (coenzyme QH2-cytochrome c reductase) by antimycin a similar or increased NADH fluorescence was observed. In addition, energy transfer from excited states of NADH (energy donor) to R123 (energy acceptor) was deduced from a decrease of NADH fluorescence after coincubation with these inhibitors and R123. Application of microscopic energy transfer spectroscopy for diagnosis of congenital mitochondrial deficiencies is currently in preparation.

  4. Energy loss in vehicle collisions from permanent deformation: an extension of the `Triangle Method'

    NASA Astrophysics Data System (ADS)

    Vangi, Dario; Begani, Filippo

    2013-06-01

    The paper presents an extension of the 'Triangle Method', to evaluate the energy loss in road accidents. The improvement of the method allows to evaluate the energy loss by both the colliding vehicles in car to car impacts, considering the main possible configurations of accident. The limits of applicability of the method are those of the Campbell's method [K.E. Campbell, Energy basis for collision severity, SAE paper 740565, Society of Automotive Engineers, Inc., Warrendale, Pennsylvania, 1974; A.G. Fonda, Principles of crush energy determination, SAE 1999-01-0106, Society of Automotive Engineers, Inc., Warrendale, Pennsylvania, 1999; N.S. Tumbas and R.A. Smith, Measurement protocol for quantifying vehicle damage from an energy basis point of view, SAE paper 880072, Society of Automotive Engineers, Inc., Warrendale, Pennsylvania, 1988; G.A. Nystrom, G. Kost, and S.M. Werner, Stiffness parameters for vehicle collision analysis, SAE paper 910119, Society of Automotive Engineers, Inc., Warrendale, Pennsylvania, 1991; J.A. Neptune, G.Y. Blair, and J.E. Flynn, A method for quantifying vehicle crush stiffness coefficients, SAE paper 920607, Society of Automotive Engineers, Inc., Warrendale, Pennsylvania, 1992]. The advantage over the usual methods are that the method does not require the knowledge of the stiffness of the vehicles and only two parameters are needed to define the damage geometry. The latter can be easily evaluated by visual inspection on a suitable photographical documentation of the damages, without the need to perform any direct measurement on the vehicles. Furthermore, the method can be used also in the very frequent cases in which some of the damage data about one of the vehicles are missing or in accidents involving lateral parts of the vehicle as zones near the wheels or the front, that have different behaviour from that tested in the classical crash tests. The error analysis developed shows that the errors due to the application of the extended

  5. Ranking paths in statistical energy analysis models with non-deterministic loss factors

    NASA Astrophysics Data System (ADS)

    Aragonès, Àngels; Guasch, Oriol

    2015-02-01

    Finding the contributions of transmission paths in statistical energy analysis (SEA) models has become an established valuable tool to detect and remedy vibro-acoustic problems. Paths are identified in SEA according to Craik's definition and recently, very efficient methods have been derived to rank them in the framework of graph theory. However, up to date classification schemes have only considered the mean values of loss factors for path comparison, their variance being ignored. This can result in significant errors in the final results. In this work it is proposed to address this problem by defining stochastic biparametric SEA graphs whose edges are assigned both, mean and variance values. Paths between subsystems are then compared according to a proposed cost function that accounts for the stochastic nature of loss factors. For an efficacious ranking of paths, the stochastic SEA graph is converted to an extended deterministic SEA graph where fast classification deterministic algorithms can be applied. The importance of nonneglecting the influence of the variance in path ranking is illustrated by means of some academic numerical examples.

  6. Remote sensing survey of energy losses from public buildings. Final report

    SciTech Connect

    Mintzer, O.; Kulacki, F.A.; Perez-Rodriquez, J.; Greenberger, S.; LaRue, R.D.

    1980-08-01

    It is the objective of this study to develop and demonstrate that thermography can be used to measure roof top heat losses from commercial and industrial buildings. Up to now, most thermography studies have been qualitative interpretations of building temperatures and identifications of excess heat lost, that is, hot spots. Thermal imaging of building surfaces is a useful qualitative tool and as shown herein, under certain calibrated conditions, may also be a quantitative tool in assessing energy losses from building envelopes. In most cases, the limitation of the utility of the thermal image arises not because the image is of poor quality, but because of the difficulty in correctly interpreting and analyzing the image. A method of calibrating thermography data is given. Several methods of presenting the data visually are also given: constant temperature contours, digital, color, gray tone and three-dimensional representation. A thermally calibrated reference area within a flat-roof surface eliminates much of the uncertainty in measuring surface temperature and provides for a measure of heat flux that is bounded by quantifiable errors. The major sources of inaccuracy and imprecision are surface material emissivity and the local environmental conditions, i.e., wind speed, cloud cover, and sky temperature.

  7. Characterization of the interfacial geomechanics in gas shales via integrated Raman spectroscopy, nanoindentation and energy dispersive X-ray spectroscopy

    NASA Astrophysics Data System (ADS)

    Ferralis, N.; Abedi, S.; Grossman, J. C.; Ulm, F.

    2012-12-01

    The geomechanical characterization of gas shales at the microscale is currently enabled by the use of grid-based nanoindentation techniques. However, the inability to probe the chemical and mineral heterogeneity of gas shales limits the identification of the geomechanical properties of individual components and phases within the probed region. The development of an integrated multiphysics approach that combines geomechanical and chemical information is crucial for the characterization of interfaces between phases, leading to the identification of regions with low yield strain. Here we present a comprehensive investigation where a spatially aligned coupled multiphysics analysis of gas shales is used to identify relevant the geomechanics of mineral and organic phases and their interfaces. This method uses grid-based nanondentation to extract the geomechanical information. Raman spectroscopy is used to identify the majority of inorganic components (calcite, quartz, anatase, pyrite, clay) as well as to characterize the diversity and maturity in the organic component (kerogen). Energy dispersive X-ray is used in combination with Raman to identify clay. With the use of clustering analysis statistical tools a correlation analysis over the full range of data (geomechanics and chemical data), we identify several mineral phases, and we clearly associate the mechanical properties (defined in terms of hardness, modulus and yield strain) with each phase. With this innovative multiphysics analysis we were able to identify interfacial phases between inorganic phases, with distinct hardness and yield strain. We find that regions between calcite-rich or quartz rich phases and clay-rich phases showed a lower than of that of the corresponding boundary phases. Hence this approach provides a viable method for the identification of the "weakest links" in gas shales with the highest probability of fracture.

  8. A method to determine stratification efficiency of thermal energy storage processes independently from storage heat losses

    SciTech Connect

    Haller, Michel Y.; Streicher, Wolfgang; Bales, Chris

    2010-06-15

    A new method for the calculation of a stratification efficiency of thermal energy storages based on the second law of thermodynamics is presented. The biasing influence of heat losses is studied theoretically and experimentally. Theoretically, it does not make a difference if the stratification efficiency is calculated based on entropy balances or based on exergy balances. In practice, however, exergy balances are less affected by measurement uncertainties, whereas entropy balances can not be recommended if measurement uncertainties are not corrected in a way that the energy balance of the storage process is in agreement with the first law of thermodynamics. A comparison of the stratification efficiencies obtained from experimental results of charging, standby, and discharging processes gives meaningful insights into the different mixing behaviors of a storage tank that is charged and discharged directly, and a tank-in-tank system whose outer tank is charged and the inner tank is discharged thereafter. The new method has a great potential for the comparison of the stratification efficiencies of thermal energy storages and storage components such as stratifying devices. (author)

  9. Continuous energy diffraction spectroscopy: A new d-space matching technique for energy dispersive synchrotron radiation diffraction

    NASA Astrophysics Data System (ADS)

    Lee, P. L.; Beno, M. A.; Knapp, G. S.; Jennings, G.

    1994-07-01

    In this article, a new technique, continuous energy diffraction spectroscopy (CEDS) is described, for diffraction experiments using a synchrotron energy dispersive polychromatic beamline. This type of beamline uses a curved crystal monochromator (polychromator) to focus a range of x-ray energies (bandwidth ˜1 keV) into a narrow (100-120 μm) line image. With a sample at this image point, using an 2D detector, we are able to measure diffracted intensities for the entire energy range of the incident beam simultaneously with limited or no motion of the sample. This method allows the collection of anomalous scattering and diffraction anomalous fine structure (DAFS) data faster and more accurately than with conventional methods. Because of the speed with which these types of diffraction experiments can be done, this method creates new options for time resolved diffraction experiments and provides new data collection strategies.

  10. Single particle plasmon spectroscopy of silver nanowires and gold nanorods.

    SciTech Connect

    N'Gom, M.; Ringnalda, J.; Mansfield, J. F.; Agarwal, A.; Kotov, N.; Zaluzec, N. J.; Norris, T. B.; Materials Science Division; Univ. of Michigan at Ann Arbor; Ohio State Univ.

    2008-01-01

    The excitation of surface plasmons in individual silver nanowires and gold nanorods is investigated by means of high-resolution electron energy loss spectroscopy in a transmission electron microscope. The transverse and longitudinal modes of these nanostructures are resolved, and the size variation of the plasmon peaks is studied. The effect of electromagnetic coupling between closely spaced nanoparticles is also observed. Finally, the relation between energy-loss measurements and optical spectroscopy of nanoparticle plasmon modes is discussed.

  11. Phase analysis of nanocomposite magnetic materials by electron energy loss spectrometry

    NASA Astrophysics Data System (ADS)

    Hébert-Souche, C.; Bernardi, J.; Schattschneider, P.; Fidler, J.; Jouffrey, B.

    2000-02-01

    EELS (electron energy loss spectrometry) in the transmission electron microscope (TEM) was used to determine the composition of a nanocrystalline magnetic specimen. The relative amounts of the hard magnetic phase Nd2Fe{14}B and the soft magnetic phase Fe3B at the point of measurement was measured by standard EELS quantification. In order to determine the structure of Fe3B present, the fine structure of the boron K-ionisation edge was analysed. Comparison of the experimental spectra with simulations of the fine structures based on the TELNES extension of the WIEN97 program package, a full potential linearised augmented plane wave approach to the calculation of electronic structure in crystals, shows that the tetragonal form of Fe3B is predominant.

  12. Parton energy loss and momentum broadening at NLO in high temperature QCD plasmas

    NASA Astrophysics Data System (ADS)

    Ghiglieri, Jacopo; Teaney, Derek

    2015-10-01

    We present an overview of a perturbative-kinetic approach to jet propagation, energy loss, and momentum broadening in a high temperature quark-gluon plasma. The leading-order kinetic equations describe the interactions between energetic jet-particles and a non-abelian plasma, consisting of on-shell thermal excitations and soft gluonic fields. These interactions include ↔ scatterings, collinear bremsstrahlung, and drag and momentum diffusion. We show how the contribution from the soft gluonic fields can be factorized into a set of Wilson line correlators on the light-cone. We review recent field-theoretical developments, rooted in the causal properties of these correlators, which simplify the calculation of the appropriate Wilson lines in thermal field theory. With these simplifications lattice measurements of transverse momentum broadening have become possible, and the kinetic equations describing parton transport have been extended to next-to-leading order in the coupling g.

  13. Parton Energy Loss and Momentum Broadening at NLO in High Temperature QCD Plasmas

    NASA Astrophysics Data System (ADS)

    Ghiglieri, Jacopo; Teaney, Derek

    We present an overview of a perturbative-kinetic approach to jet propagation, energy loss, and momentum broadening in a high temperature quark-gluon plasma. The leading-order kinetic equations describe the interactions between energetic jet-particles and a non-abelian plasma, consisting of on-shell thermal excitations and soft gluonic fields. These interactions include 2 ↔ 2 scatterings, collinear bremsstrahlung, and drag and momentum diffusion. We show how the contribution from the soft gluonic fields can be factorized into a set of Wilson line correlators on the light-cone. We review recent field-theoretical developments, rooted in the causal properties of these correlators, which simplify the calculation of the appropriate Wilson lines in thermal field theory. With these simplifications lattice measurements of transverse momentum broadening have become possible, and the kinetic equations describing parton transport have been extended to next-to-leading order in the coupling g.

  14. Simulation of Probe Position-Dependent Electron Energy-Loss Fine Structure

    SciTech Connect

    Oxley, M. P.; Kapetanakis, M. D.; Prange, Micah P.; Varela, M.; Pennycook, Stephen J.; Pantelides, Sokrates T.

    2014-03-31

    We present a theoretical framework for calculating probe-position-dependent electron energy-loss near-edge structure for the scanning transmission electron microscope by combining density functional theory with dynamical scattering theory. We show how simpler approaches to calculating near-edge structure fail to include the fundamental physics needed to understand the evolution of near-edge structure as a function of probe position and investigate the dependence of near-edge structure on probe size. It is within this framework that density functional theory should be presented, in order to ensure that variations of near-edge structure are truly due to local electronic structure and how much from the diffraction and focusing of the electron beam.

  15. Loss of the liver X receptor LXRα/β in peripheral sensory neurons modifies energy expenditure

    PubMed Central

    Mansuy-Aubert, Virginie; Gautron, Laurent; Lee, Syann; Bookout, Angie L; Kusminski, Christine M; Sun, Kai; Zhang, Yuan; Scherer, Philipp E; Mangelsdorf, David J; Elmquist, Joel K

    2015-01-01

    Peripheral neural sensory mechanisms play a crucial role in metabolic regulation but less is known about the mechanisms underlying vagal sensing itself. Recently, we identified an enrichment of liver X receptor alpha and beta (LXRα/β) in the nodose ganglia of the vagus nerve. In this study, we show mice lacking LXRα/β in peripheral sensory neurons have increased energy expenditure and weight loss when fed a Western diet (WD). Our findings suggest that the ability to metabolize and sense cholesterol and/or fatty acids in peripheral neurons is an important requirement for physiological adaptations to WDs. DOI: http://dx.doi.org/10.7554/eLife.06667.001 PMID:26076474

  16. Coupling of Multiple Coulomb Scattering with Energy Loss and Straggling in HZETRN

    NASA Technical Reports Server (NTRS)

    Mertens, Christopher J.; Wilson, John W.; Walker, Steven A.; Tweed, John

    2007-01-01

    The new version of the HZETRN deterministic transport code based on Green's function methods, and the incorporation of ground-based laboratory boundary conditions, has lead to the development of analytical and numerical procedures to include off-axis dispersion of primary ion beams due to small-angle multiple Coulomb scattering. In this paper we present the theoretical formulation and computational procedures to compute ion beam broadening and a methodology towards achieving a self-consistent approach to coupling multiple scattering interactions with ionization energy loss and straggling. Our initial benchmark case is a 60 MeV proton beam on muscle tissue, for which we can compare various attributes of beam broadening with Monte Carlo simulations reported in the open literature.

  17. Optical absorption and energy-loss spectra of aligned carbon nanotubes

    NASA Astrophysics Data System (ADS)

    García-Vidal, F. J.; Pitarke, J. M.

    2001-07-01

    Optical-absorption cross-sections and energy-loss spectra of aligned multishell carbon nanotubes are investigated, on the basis of photonic band-structure calculations. A local graphite-like dielectric tensor is assigned to every point of the tubules, and the effective transverse dielectric function of the composite is computed by solving Maxwell's equations in media with tensor-like dielectric functions. A Maxwell-Garnett-like approach appropriate to the case of infinitely long anisotropic tubules is also developed. Our full calculations indicate that the experimentally measured macroscopic dielectric function of carbon nanotube materials is the result of a strong electromagnetic coupling between the tubes. An analysis of the electric-field pattern associated with this coupling is presented, showing that in the close-packed regime the incident radiation excites a very localized tangential surface plasmon.

  18. Efficient light storage with reduced energy loss via nonlinear compensation in rubidium vapor

    NASA Astrophysics Data System (ADS)

    Wang, Gang; Zhou, Wei; Chen, Hong-Li; Xue, Yan; Wu, Jin-Hui; Xu, Huai-Liang; Gao, Jin-Yue

    2016-06-01

    We report an experimental demonstration of efficient light storage based on a modified technique of electromagnetically induced transparency in hot rubidium vapor. By introducing an auxiliary pump field to go beyond the Λ -type configuration, we find that the undesired four-wave mixing can be greatly suppressed to result in sufficiently reduced energy loss of a probe pulse. The light storage efficiency can be as high as  ∼80% within the storage time of 100 ns with the pump field applied, which is almost 6 times larger than that in the absence of the pump field. We may also amend the light storage efficiency in a linear way by increasing the optical depth of our atomic vapor even without saturation effect. We obtain, in fact, an amplified probe pulse via Raman gain during light storage and retrieval, which should have practical applications in classical and quantum information processing.

  19. Energy deposition in TEVATRON magnets from beam losses in interaction regions

    SciTech Connect

    Ginneken, A.V.

    1988-10-01

    In addition to interacting in the detector, particles produced at an interaction region also deposit energy, with less desirable consequences, in magnets and other components of the accelerator. This note briefly assesses the damage potential of these (essentially unavoidable) beam losses from the viewpoint of quenching of superconducting magnets in an upgraded Tevatron, specifically for the 1 TeV p-/ovr string/p option with a luminosity of 10/sup 31/ cm/sup - 2/ sec/sup -1/, through the results carry more generality. Related issues such as radiation damage to detector electronics or other components are not addressed here. These are thought to be less problematic at the Tevatron, as in thus far supported by operational experience. 8 refs., 10 figs.

  20. Energy loss and coronary flow simulation following hybrid stage I palliation: a hypoplastic left heart computational fluid dynamic model

    PubMed Central

    Shuhaiber, Jeffrey H.; Niehaus, Justin; Gottliebson, William; Abdallah, Shaaban

    2013-01-01

    OBJECTIVES The theoretical differences in energy losses as well as coronary flow with different band sizes for branch pulmonary arteries (PA) in hypoplastic left heart syndrome (HLHS) remain unknown. Our objective was to develop a computational fluid dynamic model (CFD) to determine the energy losses and pulmonary-to-systemic flow rates. This study was done for three different PA band sizes. METHODS Three-dimensional computer models of the hybrid procedure were constructed using the standard commercial CFD softwares Fluent and Gambit. The computer models were controlled for bilateral PA reduction to 25% (restrictive), 50% (intermediate) and 75% (loose) of the native branch pulmonary artery diameter. Velocity and pressure data were calculated throughout the heart geometry using the finite volume numerical method. Coronary flow was measured simultaneously with each model. Wall shear stress and the ratio of pulmonary-to-systemic volume flow rates were calculated. Computer simulations were compared at fixed points utilizing echocardiographic and catheter-based metric dimensions. RESULTS Restricting the PA band to a 25% diameter demonstrated the greatest energy loss. The 25% banding model produced an energy loss of 16.76% systolic and 24.91% diastolic vs loose banding at 7.36% systolic and 17.90% diastolic. Also, restrictive PA bands had greater coronary flow compared with loose PA bands (50.2 vs 41.9 ml/min). Shear stress ranged from 3.75 Pascals with restrictive PA banding to 2.84 Pascals with loose banding. Intermediate PA banding at 50% diameter achieved a Qp/Qs (closest to 1) at 1.46 systolic and 0.66 diastolic compared with loose or restrictive banding without excess energy loss. CONCLUSIONS CFD provides a unique platform to simulate pressure, shear stress as well as energy losses of the hybrid procedure. PA banding at 50% provided a balanced pulmonary and systemic circulation with adequate coronary flow but without extra energy losses incurred. PMID:23660734