National Library of Energy BETA

Sample records for ultrafast solvation dynamics

  1. Ionic Liquids: Radiation Chemistry, Solvation Dynamics and Reactivity Patterns

    SciTech Connect (OSTI)

    Wishart, J.F.

    2011-06-12

    Ionic liquids (ILs) are a rapidly expanding family of condensed-phase media with important applications in energy production, nuclear fuel and waste processing, improving the efficiency and safety of industrial chemical processes, and pollution prevention. ILs generally have low volatilities and are combustion-resistant, highly conductive, recyclable and capable of dissolving a wide variety of materials. They are finding new uses in chemical synthesis, catalysis, separations chemistry, electrochemistry and other areas. Ionic liquids have dramatically different properties compared to conventional molecular solvents, and they provide a new and unusual environment to test our theoretical understanding of primary radiation chemistry, charge transfer and other reactions. We are interested in how IL properties influence physical and dynamical processes that determine the stability and lifetimes of reactive intermediates and thereby affect the courses of reactions and product distributions. We study these issues by characterization of primary radiolysis products and measurements of their yields and reactivity, quantification of electron solvation dynamics and scavenging of electrons in different states of solvation. From this knowledge we wish to learn how to predict radiolytic mechanisms and control them or mitigate their effects on the properties of materials used in nuclear fuel processing, for example, and to apply IL radiation chemistry to answer questions about general chemical reactivity in ionic liquids that will aid in the development of applications listed above. Very early in our radiolysis studies it became evident that the slow solvation dynamics of the excess electron in ILs (which vary over a wide viscosity range) increase the importance of pre-solvated electron reactivity and consequently alter product distributions and subsequent chemistry. This difference from conventional solvents has profound effects on predicting and controlling radiolytic yields, which need to be quantified for the successful use under radiolytic conditions. Electron solvation dynamics in ILs are measured directly when possible and estimated using proxies (e.g. coumarin-153 dynamic emission Stokes shifts or benzophenone anion solvation) in other cases. Electron reactivity is measured using ultrafast kinetics techniques for comparison with the solvation process.

  2. Solvation!

    SciTech Connect (OSTI)

    Ivana Adamovic

    2004-12-19

    This dissertation consists of two closely related parts: theory development and coding of correlation effects in a model potential for solvation, and study of solvent effects on chemical reactions and processes. The effective fragment potential (EFP) method has been re-parameterized, using density functional theory (DFT), more specifically, the B3LYP functional. The DFT based EFP method includes short-range correlation effects; hence it is a first step in incorporating the treatment of correlation in the EFP solvation model. In addition, the gradient of the charge penetration term in the EFP model was derived and coded. The new method has been implemented in the electronic structure code GAMESS and is in use. Formulas for the dynamic dipole polarizability, C{sub 6} dispersion coefficient and dispersion energy were derived and coded as a part of a treatment of the dispersion interactions in the general solvation model, EFP2. Preliminary results are in good agreement with experimental and other theoretical data. The DFT based EFP (EFP1/DFT) method was used in the study of microsolvation effects on the S{sub N}2 substitution reaction, between chloride and methyl bromide. Changes in the central barrier, for several lowest lying isomers of the systems with one, two, three and four waters, were studied using second order perturbation theory (MP2), DFT and mixed quantum mechanics (QM)/(EFP1/DFT) methods. EFP1/DFT is found to reproduce QM results with high accuracy, at just a fraction of the cost. Molecular structures and potential energy surfaces for IHI{sup -} {center_dot} Ar{sub n} (n=1-7) were studied using the MP2 method. Experimentally observed trends in the structural arrangement of the Ar atoms were explained through the analysis of the geometrical parameters and three-dimensional MP2 molecular electrostatic potentials.

  3. Ultrafast studies of solution dynamics

    SciTech Connect (OSTI)

    Woodruff, W.H.; Dyer, R.B.; Callender, R.H.

    1997-10-01

    This is the final report of a one-year, Laboratory Directed Research and Development (LDRD) project at Los Alamos National Laboratory (LANL). Fast chemical dynamics generally must be initiated photochemically. This limits the applicability of modern laser methods for following the structural changes that occur during chemical and biological reactions to those systems that have an electronic chromophore that has a significant yield of photoproduct when excited. This project has developed a new and entirely general approach to ultrafast initiation of reactions in solution: laser-induced temperature jump (T-jump). The results open entire new fields of study of ultrafast molecular dynamics in solution. The authors have demonstrated the T-jump technique on time scales of 50 ps and longer, and have applied it to study of the fast events in protein folding. They find that a general lifetime of alpha-helix formation is ca 100 ns, and that tertiary folds (in apomyoglobin) form in ca 100 {mu}s.

  4. Ultrafast Core-Hole Induced Dynamics in Water

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    isotope substitution experiments and molecular dynamics simulations, researchers from Sweden, Germany, and the U.S. have shown that the ultrafast (0- to 10-fs) dissociation...

  5. IONIC LIQUIDS: RADIATION CHEMISTRY, SOLVATION DYNAMICS AND REACTIVITY PATTERNS.

    SciTech Connect (OSTI)

    WISHART,J.F.

    2007-10-01

    energy production, nuclear fuel and waste processing, improving the efficiency and safety of industrial chemical processes, and pollution prevention. ILs are generally nonvolatile, noncombustible, highly conductive, recyclable and capable of dissolving a wide variety of materials. They are finding new uses in chemical synthesis, catalysis, separations chemistry, electrochemistry and other areas. Ionic liquids have dramatically different properties compared to conventional molecular solvents, and they provide a new and unusual environment to test our theoretical understanding of charge transfer and other reactions. We are interested in how IL properties influence physical and dynamical processes that determine the stability and lifetimes of reactive intermediates and thereby affect the courses of chemical reactions and product distributions. Successful use of ionic liquids in radiation-filled environments, where their safety advantages could be significant, requires an understanding of ionic liquid radiation chemistry. For example, characterizing the primary steps of IL radiolysis will reveal radiolytic degradation pathways and suggest ways to prevent them or mitigate their effects on the properties of the material. An understanding of ionic liquid radiation chemistry will also facilitate pulse radiolysis studies of general chemical reactivity in ILs, which will aid in the development of applications listed above. Very early in our radiolysis studies it became evident that slow solvation dynamics of the excess electron in ILs (which vary over a wide viscosity range) increases the importance of pre-solvated electron reactivity and consequently alters product distributions. Parallel studies of IL solvation phenomena using coumarin-153 dynamic Stokes shifts and polarization anisotropy decay rates are done to compare with electron solvation studies and to evaluate the influence of ILs on charge transport processes. Methods. Picosecond pulse radiolysis studies at BNL's Laser-Electron Accelerator Facility (LEAF) are used to identify reactive species in ionic liquids and measure their solvation and reaction rates. We and our collaborators (R. Engel (Queens College, CUNY) and S. Lall-Ramnarine, (Queensborough CC, CUNY)) develop and characterize new ionic liquids specifically designed for our radiolysis and solvation dynamics studies. IL solvation and rotational dynamics are measured by TCSPC and fluorescence upconversion measurements in the laboratory of E. W. Castner at Rutgers Univ. Investigations of radical species in irradiated ILs are carried out at ANL by I. Shkrob and S. Chemerisov using EPR spectroscopy. Diffusion rates are obtained by PGSE NMR in S. Greenbaum's lab at Hunter College, CUNY and S. Chung's lab at William Patterson U. Professor Mark Kobrak of CUNY Brooklyn College performs molecular dynamics simulations of solvation processes. A collaboration with M. Dietz and coworkers at ANL is centered around the properties and radiolytic behavior of ionic liquids for nuclear separations. Collaborations with C. Reed (UC Riverside), D. Gabel (U. Bremen) and J. Davis (U. South Alabama) are aimed at characterizing the radiolytic and other properties of borated ionic liquids, which could be used to make fissile material separations processes inherently safe from criticality accidents.

  6. Ionic Liquids: Radiation Chemistry, Solvation Dynamics and Reactivity Patterns

    SciTech Connect (OSTI)

    Wishart,J.F.

    2008-09-29

    Ionic liquids (ILs) are a rapidly expanding family of condensed-phase media with important applications in energy production, nuclear fuel and waste processing, improving the efficiency and safety of industrial chemical processes, and pollution prevention. ILs are generally nonvolatile, noncombustible, highly conductive, recyclable and capable of dissolving a wide variety of materials. They are finding new uses in chemical synthesis, catalysis, separations chemistry, electrochemistry and other areas. Ionic liquids have dramatically different properties compared to conventional molecular solvents, and they provide a new and unusual environment to test our theoretical understanding of charge transfer and other reactions. We are interested in how IL properties influence physical and dynamical processes that determine the stability and lifetimes of reactive intermediates and thereby affect the courses of chemical reactions and product distributions. Successful use of ionic liquids in radiation-filled environments, where their safety advantages could be significant, requires an understanding of ionic liquid radiation chemistry. For example, characterizing the primary steps of IL radiolysis will reveal radiolytic degradation pathways and suggest ways to prevent them or mitigate their effects on the properties of the material. An understanding of ionic liquid radiation chemistry will also facilitate pulse radiolysis studies of general chemical reactivity in ILs, which will aid in the development of applications listed above. Very early in our radiolysis studies it became evident that slow solvation dynamics of the excess electron in ILs (which vary over a wide viscosity range) increases the importance of pre-solvated electron reactivity and consequently alters product distributions. Parallel studies of IL solvation phenomena using coumarin-153 dynamic Stokes shifts and polarization anisotropy decay rates are done to compare with electron solvation studies and to evaluate the influence of ILs on charge transport processes. Picosecond pulse radiolysis studies at BNL's Laser-Electron Accelerator Facility (LEAF) are used to identify reactive species in ionic liquids and measure their solvation and reaction rates. We and our collaborators (R. Engel (Queens College, CUNY) and S. Lall-Ramnarine, (Queensborough CC, CUNY)) develop and characterize new ionic liquids specifically designed for our radiolysis and solvation dynamics studies. IL solvation and rotational dynamics are measured by TCSPC and fluorescence upconversion measurements in the laboratory of E. W. Castner at Rutgers Univ. Investigations of radical species in irradiated ILs are carried out at ANL by I. Shkrob and S. Chemerisov using EPR spectroscopy. Diffusion rates are obtained by PGSE NMR in S. Greenbaum's lab at Hunter College, CUNY and S. Chung's lab at William Patterson U. Professor Mark Kobrak of CUNY Brooklyn College performs molecular dynamics simulations of solvation processes. A collaboration with M. Dietz at U. Wisc. Milwaukee is centered around the properties and radiolytic behavior of ionic liquids for nuclear separations. Collaborations with C. Reed (UC Riverside), D. Gabel (U. Bremen) and J. Davis (U. South Alabama) are aimed at characterizing the radiolytic and other properties of borated ionic liquids, which could be used to make fissile material separations processes inherently safe from criticality accidents.

  7. Ultrafast carriers dynamics in filled-skutterudites

    SciTech Connect (OSTI)

    Guo, Liang; Xu, Xianfan; Salvador, James R.

    2015-06-08

    Carrier dynamics of filled-skutterudites, an important class of thermoelectric materials, is investigated using ultrafast optical spectroscopy. By tuning the wavelength of the probe laser, charge transfers at different electronic energy levels are interrogated. Analysis based on the Kramers-Kronig relation explains the complex spectroscopy data, which is mainly due to band filling caused by photo-excited carriers and free carrier absorption. The relaxation time of hot carriers is found to be about 0.40.6 ps, depending on the electronic energy level, and the characteristic time for carrier-phonon equilibrium is about 0.95 ps. These studies of carrier dynamics, which fundamentally determines the transport properties of thermoelectric material, can provide guidance for the design of materials.

  8. Ultrafast Core-Hole Induced Dynamics in Water

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Ultrafast Core-Hole Induced Dynamics in Water Ultrafast Core-Hole Induced Dynamics in Water Print Wednesday, 22 February 2006 00:00 A thorough understanding of the chemical processes that are initiated when radiation interacts with aqueous systems is essential for many diverse fields, from condensed matter physics to medicine to environmental science. An incoming photon with enough energy to produce a core hole in a water molecule sets off motions that can affect bonding configurations, which in

  9. Ultrafast Dynamic Response of Single Crystal PETN and Beta-HMX...

    Office of Scientific and Technical Information (OSTI)

    Conference: Ultrafast Dynamic Response of Single Crystal PETN and Beta-HMX Citation Details In-Document Search Title: Ultrafast Dynamic Response of Single Crystal PETN and Beta-HMX...

  10. Ultrafast Magnetism Dynamics Measure Using Tabletop Ultrafast EUV Sources

    SciTech Connect (OSTI)

    Silva, Thomas J.; Murnane, Margaret

    2013-08-21

    In our work to date, we made two significant advances. First we demonstrated element-selective demagnetization dynamics for the first time, with a record time resolution for x-ray probing of 55 fs. Second, in new work, we were able to probe the timescale of the exchange interaction in magnetic materials, also for the first time. Our measurements were made using the transverse magneto-optic Kerr effect (T-MOKE) geometry, since the reflectivity of a magnetic material changes with the direction of the magnetization vector of a surface. In our experiment, we periodically reversed the magnetization direction of a grating structure made of Permalloy (Ni80Fe20) using an external magnetic field. To achieve maximum contrast, we used HHG light spanning the M-shell (3p) absorption edges of Fe and Ni. Our characterization of the static magnetization of a Permalloy sample shows high magnetic asymmetry at photon energies just above and below the absorption edges at 55 eV and 65 eV, respectively. This result is in excellent agreement with measurements done on the same using a synchrotron source.

  11. Ultrafast Core-Hole Induced Dynamics in Water

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Ultrafast Core-Hole Induced Dynamics in Water Print A thorough understanding of the chemical processes that are initiated when radiation interacts with aqueous systems is essential for many diverse fields, from condensed matter physics to medicine to environmental science. An incoming photon with enough energy to produce a core hole in a water molecule sets off motions that can affect bonding configurations, which in turn affect subsequent chemical-reaction pathways. However, it is a fundamental

  12. Ultrafast Core-Hole Induced Dynamics in Water

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Ultrafast Core-Hole Induced Dynamics in Water Print A thorough understanding of the chemical processes that are initiated when radiation interacts with aqueous systems is essential for many diverse fields, from condensed matter physics to medicine to environmental science. An incoming photon with enough energy to produce a core hole in a water molecule sets off motions that can affect bonding configurations, which in turn affect subsequent chemical-reaction pathways. However, it is a fundamental

  13. Ultrafast Core-Hole Induced Dynamics in Water

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Ultrafast Core-Hole Induced Dynamics in Water Print A thorough understanding of the chemical processes that are initiated when radiation interacts with aqueous systems is essential for many diverse fields, from condensed matter physics to medicine to environmental science. An incoming photon with enough energy to produce a core hole in a water molecule sets off motions that can affect bonding configurations, which in turn affect subsequent chemical-reaction pathways. However, it is a fundamental

  14. Ultrafast Core-Hole Induced Dynamics in Water

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Ultrafast Core-Hole Induced Dynamics in Water Print A thorough understanding of the chemical processes that are initiated when radiation interacts with aqueous systems is essential for many diverse fields, from condensed matter physics to medicine to environmental science. An incoming photon with enough energy to produce a core hole in a water molecule sets off motions that can affect bonding configurations, which in turn affect subsequent chemical-reaction pathways. However, it is a fundamental

  15. Ultrafast Core-Hole Induced Dynamics in Water

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Ultrafast Core-Hole Induced Dynamics in Water Print A thorough understanding of the chemical processes that are initiated when radiation interacts with aqueous systems is essential for many diverse fields, from condensed matter physics to medicine to environmental science. An incoming photon with enough energy to produce a core hole in a water molecule sets off motions that can affect bonding configurations, which in turn affect subsequent chemical-reaction pathways. However, it is a fundamental

  16. Ultrafast Core-Hole Induced Dynamics in Water

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Ultrafast Core-Hole Induced Dynamics in Water Print A thorough understanding of the chemical processes that are initiated when radiation interacts with aqueous systems is essential for many diverse fields, from condensed matter physics to medicine to environmental science. An incoming photon with enough energy to produce a core hole in a water molecule sets off motions that can affect bonding configurations, which in turn affect subsequent chemical-reaction pathways. However, it is a fundamental

  17. Ultrafast dynamic ellipsometry and spectroscopy of laser shocked materials

    SciTech Connect (OSTI)

    Mcgrane, Shawn David [Los Alamos National Laboratory; Bolme, Cindy B [Los Alamos National Laboratory; Whitley, Von H [Los Alamos National Laboratory; Moore, David S [Los Alamos National Laboratory

    2010-01-01

    Shock waves create extreme states of matter with very high pressures, temperatures, and volumetric compressions, at an exceedingly rapid rate of change. We review how to use a beamsplitter and a note card to turn a typical chirp pulse amplified femtosecond laser system into an ultrafast shock dynamics machine. Open scientific questions that can be addressed with such an apparatus are described. We report on the development of several single shot time resolved diagnostics needed to answer these questions. These single shot diagnostics are expected to be broadly applicable to other types of laser ablation experiments. Experimental results measured from shocked material dynamics of several systems are detailed. Finally, we report on progress towards using transient absorption as a measure of electronic excitation and coherent Raman as a picosecond probe of temperature in shock compressed condensed matter.

  18. Ultrafast Structural Dynamics in Combustion Relevant Model Systems

    SciTech Connect (OSTI)

    Weber, Peter M.

    2014-03-31

    The research project explored the time resolved structural dynamics of important model reaction system using an array of novel methods that were developed specifically for this purpose. They include time resolved electron diffraction, time resolved relativistic electron diffraction, and time resolved Rydberg fingerprint spectroscopy. Toward the end of the funding period, we also developed time-resolved x-ray diffraction, which uses ultrafast x-ray pulses at LCLS. Those experiments are just now blossoming, as the funding period expired. In the following, the time resolved Rydberg Fingerprint Spectroscopy is discussed in some detail, as it has been a very productive method. The binding energy of an electron in a Rydberg state, that is, the energy difference between the Rydberg level and the ground state of the molecular ion, has been found to be a uniquely powerful tool to characterize the molecular structure. To rationalize the structure sensitivity we invoke a picture from electron diffraction: when it passes the molecular ion core, the Rydberg electron experiences a phase shift compared to an electron in a hydrogen atom. This phase shift requires an adjustment of the binding energy of the electron, which is measurable. As in electron diffraction, the phase shift depends on the molecular, geometrical structure, so that a measurement of the electron binding energy can be interpreted as a measurement of the molecules structure. Building on this insight, we have developed a structurally sensitive spectroscopy: the molecule is first elevated to the Rydberg state, and the binding energy is then measured using photoelectron spectroscopy. The molecules structure is read out as the binding energy spectrum. Since the photoionization can be done with ultrafast laser pulses, the technique is inherently capable of a time resolution in the femtosecond regime. For the purpose of identifying the structures of molecules during chemical reactions, and for the analysis of molecular species in the hot environments of combustion processes, there are several features that make the Rydberg ionization spectroscopy uniquely useful. First, the Rydberg electrons orbit is quite large and covers the entire molecule for most molecular structures of combustion interest. Secondly, the ionization does not change vibrational quantum numbers, so that even complicated and large molecules can be observed with fairly well resolved spectra. In fact, the spectroscopy is blind to vibrational excitation of the molecule. This has the interesting consequence for the study of chemical dynamics, where the molecules are invariably very energetic, that the molecular structures are observed unobstructed by the vibrational congestion that dominates other spectroscopies. This implies also that, as a tool to probe the time-dependent structural dynamics of chemically interesting molecules, Rydberg spectroscopy may well be better suited than electron or x-ray diffraction. With recent progress in calculating Rydberg binding energy spectra, we are approaching the point where the method can be evolved into a structure determination method. To implement the Rydberg ionization spectroscopy we use a molecular beam based, time-resolved pump-probe multi-photon ionization/photoelectron scheme in which a first laser pulse excites the molecule to a Rydberg state, and a probe pulse ionizes the molecule. A time-of-flight detector measures the kinetic energy spectrum of the photoelectrons. The photoelectron spectrum directly provides the binding energy of the electron, and thereby reveals the molecules time-dependent structural fingerprint. Only the duration of the laser pulses limits the time resolution. With a new laser system, we have now reached time resolutions better than 100 fs, although very deep UV wavelengths (down to 190 nm) have slightly longer instrument functions. The structural dynamics of molecules in Rydberg-excited states is obtained by delaying the probe ionization photon from the pump photon; the structural dynamics of molecules in their ground state or e

  19. Ultrafast Dynamic Response of Single Crystal PETN and Beta-HMX (Conference)

    Office of Scientific and Technical Information (OSTI)

    | SciTech Connect Conference: Ultrafast Dynamic Response of Single Crystal PETN and Beta-HMX Citation Details In-Document Search Title: Ultrafast Dynamic Response of Single Crystal PETN and Beta-HMX Authors: Zaug, J M ; Armstrong, M R ; Crowhurst, J C ; Feranti, L ; Swan, R ; Gross, R ; Teshlich, N E ; Wall, M ; Austin, R A ; Fried, L E Publication Date: 2014-06-30 OSTI Identifier: 1149550 Report Number(s): LLNL-CONF-656341 DOE Contract Number: DE-AC52-07NA27344 Resource Type: Conference

  20. Dynamics of electron solvation in methanol: Excited state relaxation and generation by charge-transfer-to-solvent

    SciTech Connect (OSTI)

    Elkins, Madeline H.; Williams, Holly L.; Neumark, Daniel M.

    2015-06-21

    The charge-transfer-to-solvent dynamics (CTTS) and excited state relaxation mechanism of the solvated electron in methanol are studied by time-resolved photoelectron spectroscopy on a liquid methanol microjet by means of two-pulse and three-pulse experiments. In the two-pulse experiment, CTTS excitation is followed by a probe photoejection pulse. The resulting time-evolving photoelectron spectrum reveals multiple time scales characteristic of relaxation and geminate recombination of the initially generated electron which are consistent with prior results from transient absorption. In the three-pulse experiment, the relaxation dynamics of the solvated electron following electronic excitation are measured. The internal conversion lifetime of the excited electron is found to be 130 40 fs, in agreement with extrapolated results from clusters and the non-adiabatic relaxation mechanism.

  1. Electron Solvation Dynamics and Reactivity in Ionic Liquids Observed by Picosecond RadiolysisTechniques

    SciTech Connect (OSTI)

    Wishart J. F.; Funston, A.M.; Szreder, T.; Cook, A.R.; Gohdo, M.

    2012-01-01

    On time scales of a nanosecond or less, radiolytically-generated excess electrons in ionic liquids undergo solvation processes and reactions that determine all subsequent chemistry and the accumulation of radiolytic damage. Using picosecond pulse radiolysis detection methods, we observed and quantified the solvation response of the electron in 1-methyl-1-butyl-pyrrolidinium bis(trifluoromethylsulfonyl)amide and used it to understand electron scavenging by a typical solute, duroquinone.

  2. Ultrafast Core-Hole Induced Dynamics in Water

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    with pump-probe measurements. Using a combination of isotope substitution experiments and molecular dynamics simulations, researchers from Sweden, Germany, and the U.S. have shown...

  3. Ultrafast Core-Hole Induced Dynamics in Water

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Waters If you look deeply enough at even the stillest of waters, as deep as the molecular level, you will find a surprisingly turbulent, dynamic universe. The water...

  4. Ultrafast Core-Hole Induced Dynamics in Water

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    radiation therapy. The detailed study of substances in the condensed and dynamic liquid state poses unique challenges that aren't an issue with isolated gas molecules or solids...

  5. Ultrafast carrier dynamics in the large-magnetoresistance material WTe2

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Dai, Y. M.; Bowlan, J.; Li, H.; Miao, H.; Wu, S. F.; Kong, W. D.; Shi, Y. G.; Trugman, S. A.; Zhu, J. -X.; Ding, H.; et al

    2015-10-07

    In this study, ultrafast optical pump-probe spectroscopy is used to track carrier dynamics in the large-magnetoresistance material WTe2. Our experiments reveal a fast relaxation process occurring on a subpicosecond time scale that is caused by electron-phonon thermalization, allowing us to extract the electron-phonon coupling constant. An additional slower relaxation process, occurring on a time scale of ~5–15 ps, is attributed to phonon-assisted electron-hole recombination. As the temperature decreases from 300 K, the time scale governing this process increases due to the reduction of the phonon population. However, below ~50 K, an unusual decrease of the recombination time sets in, mostmore » likely due to a change in the electronic structure that has been linked to the large magnetoresistance observed in this material.« less

  6. Lithium Ion Solvation and Diffusion in Bulk Organic Electrolytes...

    Office of Scientific and Technical Information (OSTI)

    Lithium Ion Solvation and Diffusion in Bulk Organic Electrolytes from First Principles and Classical Reactive Molecular Dynamics Citation Details In-Document Search Title: Lithium...

  7. Lithium Ion Solvation and Diffusion in Bulk Organic Electrolytes...

    Office of Scientific and Technical Information (OSTI)

    Conference: Lithium Ion Solvation and Diffusion in Bulk Organic Electrolytes from First Principles Molecular Dynamics Citation Details In-Document Search Title: Lithium Ion...

  8. Ultrafast dynamics of liquid water: Frequency fluctuations of the OH stretch and the HOH bend

    SciTech Connect (OSTI)

    Imoto, Sho; Xantheas, Sotiris S.; Saito, Shinji

    2013-07-28

    Frequency fluctuations of the OH stretch and the HOH bend in liquid water are reported from the third-order response function evaluated using the TTM3-F potential for water. The simulated two-dimensional infrared (IR) spectra of the OH stretch are similar to previously reported theoretical results. The present study suggests that the frequency fluctuation of the HOH bend is faster than that of the OH stretch. The ultrafast loss of the frequency correlation of the HOH bend is due to the strong couplings with the OH stretch as well as the intermolecular hydrogen bond bend.

  9. Dynamic Processes in Biology, Chemistry, and Materials Science: Opportunities for UltraFast Transmission Electron Microscopy - Workshop Summary Report

    SciTech Connect (OSTI)

    Kabius, Bernd C.; Browning, Nigel D.; Thevuthasan, Suntharampillai; Diehl, Barbara L.; Stach, Eric A.

    2012-07-25

    This report summarizes a 2011 workshop that addressed the potential role of rapid, time-resolved electron microscopy measurements in accelerating the solution of important scientific and technical problems. A series of U.S. Department of Energy (DOE) and National Academy of Science workshops have highlighted the critical role advanced research tools play in addressing scientific challenges relevant to biology, sustainable energy, and technologies that will fuel economic development without degrading our environment. Among the specific capability needs for advancing science and technology are tools that extract more detailed information in realistic environments (in situ or operando) at extreme conditions (pressure and temperature) and as a function of time (dynamic and time-dependent). One of the DOE workshops, Future Science Needs and Opportunities for Electron Scattering: Next Generation Instrumentation and Beyond, specifically addressed the importance of electron-based characterization methods for a wide range of energy-relevant Grand Scientific Challenges. Boosted by the electron optical advancement in the last decade, a diversity of in situ capabilities already is available in many laboratories. The obvious remaining major capability gap in electron microscopy is in the ability to make these direct in situ observations over a broad spectrum of fast (µs) to ultrafast (picosecond [ps] and faster) temporal regimes. In an effort to address current capability gaps, EMSL, the Environmental Molecular Sciences Laboratory, organized an Ultrafast Electron Microscopy Workshop, held June 14-15, 2011, with the primary goal to identify the scientific needs that could be met by creating a facility capable of a strongly improved time resolution with integrated in situ capabilities. The workshop brought together more than 40 leading scientists involved in applying and/or advancing electron microscopy to address important scientific problems of relevance to DOE’s research mission. This workshop built on previous workshops and included three breakout sessions identifying scientific challenges in biology, biogeochemistry, catalysis, and materials science frontier areas of fundamental science that underpin energy and environmental science that would significantly benefit from ultrafast transmission electron microscopy (UTEM). In addition, the current status of time-resolved electron microscopy was examined, and the technologies that will enable future advances in spatio-temporal resolution were identified in a fourth breakout session.

  10. Ultrafast myoglobin structural dynamics observed with an X-ray free-electron laser

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Levantino, Matteo; Schirò, Giorgio; Lemke, Henrik Till; Cottone, Grazia; Glownia, James Michael; Zhu, Diling; Chollet, Mathieu; Ihee, Hyotcherl; KAIST, Daejeon; Cupane, Antonio; et al

    2015-04-02

    Light absorption can trigger biologically relevant protein conformational changes. The light induced structural rearrangement at the level of a photoexcited chromophore is known to occur in the femtosecond timescale and is expected to propagate through the protein as a quake-like intramolecular motion. Here we report direct experimental evidence of such ‘proteinquake’ observed in myoglobin through femtosecond X-ray solution scattering measurements performed at the Linac Coherent Light Source X-ray free-electron laser. An ultrafast increase of myoglobin radius of gyration occurs within 1 picosecond and is followed by a delayed protein expansion. As the system approaches equilibrium it undergoes damped oscillations withmore » a ~3.6-picosecond time period. Our results unambiguously show how initially localized chemical changes can propagate at the level of the global protein conformation in the picosecond timescale.« less

  11. Ultrafast myoglobin structural dynamics observed with an X-ray free-electron laser

    SciTech Connect (OSTI)

    Levantino, Matteo; Schir, Giorgio; Lemke, Henrik Till; Cottone, Grazia; Glownia, James Michael; Zhu, Diling; Chollet, Mathieu; Ihee, Hyotcherl; KAIST, Daejeon; Cupane, Antonio; Cammarata, Marco

    2015-04-02

    Light absorption can trigger biologically relevant protein conformational changes. The light induced structural rearrangement at the level of a photoexcited chromophore is known to occur in the femtosecond timescale and is expected to propagate through the protein as a quake-like intramolecular motion. Here we report direct experimental evidence of such proteinquake observed in myoglobin through femtosecond X-ray solution scattering measurements performed at the Linac Coherent Light Source X-ray free-electron laser. An ultrafast increase of myoglobin radius of gyration occurs within 1 picosecond and is followed by a delayed protein expansion. As the system approaches equilibrium it undergoes damped oscillations with a ~3.6-picosecond time period. Our results unambiguously show how initially localized chemical changes can propagate at the level of the global protein conformation in the picosecond timescale.

  12. Ultrafast Transformations in Superionic Nanocrystals

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Ultrafast Transformations in Superionic Nanocrystals Ultrafast Transformations in Superionic Nanocrystals Print Wednesday, 29 January 2014 00:00 A superionic material is a multi-component solid with simultaneous characteristics of both a solid and a liquid. Above a critical temperature associated with a structural phase transition, one of the atomic species in the material will exhibit liquid-like ionic conductivity and dynamic disorder within the rigid crystalline structure of the other.

  13. Ultrafast dynamics of liquid water: Energy relaxation and transfer processes of the OH stretch and the HOH bend

    SciTech Connect (OSTI)

    Imoto, Sho; Xantheas, Sotiris S.; Saito, Shinji

    2015-08-27

    The vibrational energy relaxation and transfer processes of the OH stretching and the HOH bending vibrations in liquid water are investigated via the theoretical calculation of the pump-probe spectra obtained from non-equilibrium molecular dynamics simulations with the TTM3-F interaction potential. The excitation of the OH stretch induces an instantaneous response of the high frequency librational motions in the 600-1000 cm-1 range. In addition, the excess energy of the OH stretch of a water molecule quickly transfers to the OH stretches of molecules in its first hydration shell with a time constant of ~50 fs, followed by relaxation to the HOH bends of the surrounding molecules with a time constant of 230 fs. The excitation of the HOH bend also results in the ultrafast excitation of the high frequency librational motions. The energy of the excited HOH bend of a water molecule decays, with a time constant of 200 fs, mainly to the relaxation of the HOH bends of its surrounding molecules. The energies of the HOH bends were found to transfer quickly to the intermolecular motions via the coupling with the high frequency librational motions. The excess energy of the OH stretch or the HOH bend relaxes to the high frequency intermolecular librational motions and eventually to the hot ground state with a time scale of ~1 ps via the coupling with the librational and translational motions. The energy relaxation and transfer processes were found to depend on the local hydrogen bonding network; the relaxations of the excess energy of the OH stretch and the HOH bend of four- and five-coordinated molecules are faster than those of a three-coordinated molecule due to the delocalization of the vibrational motions of the former (four- and five-coordinated molecules) compared to those of the later (three-coordinated molecules). The present results highlight the importance of the high frequency intermolecular librational modes in facilitating the ultrafast energy relaxation process in liquid water via their strong nonlinear couplings with the intramolecular OH stretching and HOH bending vibrations. S.S.X. acknowledges the support of the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences, and Biosciences. Pacific Northwest National Laboratory (PNNL) is a multiprogram national laboratory operated for DOE by Battelle. The calculation was carried out using the computing resources at the Research Center for Computational Science in Okazaki, Japan.

  14. Electrolyte Solvation and Ionic Association. VI. Acetonitrile-Lithium Salt

    Office of Scientific and Technical Information (OSTI)

    Mixtures: Highly Associated Salts Revisited (Journal Article) | SciTech Connect Electrolyte Solvation and Ionic Association. VI. Acetonitrile-Lithium Salt Mixtures: Highly Associated Salts Revisited Citation Details In-Document Search Title: Electrolyte Solvation and Ionic Association. VI. Acetonitrile-Lithium Salt Mixtures: Highly Associated Salts Revisited Molecular dynamics (MD) simulations of acetonitrile (AN) mixtures with LiBF4, LiCF3SO3 and LiCF3CO2 provide extensive details about the

  15. Single shot ultrafast dynamic ellipsometry (UDE) of laser-driven shocks in single crystal explosives

    SciTech Connect (OSTI)

    Whitley, Von H; Mcgrane, Shawn D; Moore, David S; Eakins, Dan E; Bolme, Cindy A

    2009-01-01

    We report on the first experiments to measure states in shocked energetic single crystals with dynamic ellipsometry. We demonstrate that these ellipsometric techniques can produce reasonable Hugoniot values using small amounts of crystalline RDX and PETN. Pressures, particle velocities and shock velocities obtained using shocked ellipsometry are comparable to those found using gas-gun flyer plates and molecular dynamics calculations. The adaptation of the technique from uniform thin films of polymers to thick non-perfect crystalline materials was a significant achievement. Correct sample preparation proved to be a crucial component. Through trial and error, we were able to resolve polishing issues, sample quality problems, birefringence effects and mounting difficulties that were not encountered using thin polymer films.

  16. MAUI: Modeling, Analysis, and Ultrafast Imaging | Argonne National...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    interfaces. Our goal is to integrate ultrafast time-resolved imaging with large-scale molecular dynamics modeling and in situ data analysis and visualization. This will allow...

  17. Structural Interactions within Lithium Salt Solvates: Acyclic...

    Office of Scientific and Technical Information (OSTI)

    Structural Interactions within Lithium Salt Solvates: Acyclic Carbonates and Esters Citation Details In-Document Search Title: Structural Interactions within Lithium Salt Solvates: ...

  18. Solvate Structures and Computational/Spectroscopic Characterization...

    Office of Scientific and Technical Information (OSTI)

    Solvate Structures and ComputationalSpectroscopic Characterization of LiPF6 Electrolytes Citation Details In-Document Search Title: Solvate Structures and Computational...

  19. Solvate Structures and Computational/Spectroscopic Characterization...

    Office of Scientific and Technical Information (OSTI)

    Solvate Structures and ComputationalSpectroscopic Characterization of LiBF4 Electrolytes Citation Details In-Document Search Title: Solvate Structures and Computational...

  20. Effect of carrier recombination on ultrafast carrier dynamics in thin films of the topological insulator Bi{sub 2}Se{sub 3}

    SciTech Connect (OSTI)

    Glinka, Yuri D.; Babakiray, Sercan; Johnson, Trent A.; Holcomb, Mikel B.; Lederman, David

    2014-10-27

    Transient reflectivity (TR) from thin films (640?nm thick) of the topological insulator Bi{sub 2}Se{sub 3} revealed ultrafast carrier dynamics, which suggest the existence of both radiative and non-radiative recombination between electrons residing in the upper cone of initially unoccupied high energy Dirac surface states (SS) and holes residing in the lower cone of occupied low energy Dirac SS. The modeling of measured TR traces allowed us to conclude that recombination is induced by the depletion of bulk electrons in films below ?20?nm thick due to the charge captured on the surface defects. We predict that such recombination processes can be observed using time-resolved photoluminescence techniques.

  1. 2D heterodyne-detected sum frequency generation study on the ultrafast vibrational dynamics of H{sub 2}O and HOD water at charged interfaces

    SciTech Connect (OSTI)

    Inoue, Ken-ichi; Singh, Prashant C.; Nihonyanagi, Satoshi; Tahara, Tahei; Yamaguchi, Shoichi

    2015-06-07

    Two-dimensional heterodyne-detected vibrational sum-frequency generation (2D HD-VSFG) spectroscopy is applied to study the ultrafast vibrational dynamics of water at positively charged aqueous interfaces, and 2D HD-VSFG spectra of cetyltrimethylammonium bromide (CTAB)/water interfaces in the whole hydrogen-bonded OH stretch region (3000 cm{sup ?1} ? ?{sub pump} ? 3600 cm{sup ?1}) are measured. 2D HD-VSFG spectrum of the CTAB/isotopically diluted water (HOD-D{sub 2}O) interface exhibits a diagonally elongated bleaching lobe immediately after excitation, which becomes round with a time constant of ?0.3 ps due to spectral diffusion. In contrast, 2D HD-VSFG spectrum of the CTAB/H{sub 2}O interface at 0.0 ps clearly shows two diagonal peaks and their cross peaks in the bleaching region, corresponding to the double peaks observed at 3230 cm{sup ?1} and 3420 cm{sup ?1} in the steady-state HD-VSFG spectrum. Horizontal slices of the 2D spectrum show that the relative intensity of the two peaks of the bleaching at the CTAB/H{sub 2}O interface gradually change with the change of the pump frequency. We simulate the pump-frequency dependence of the bleaching feature using a model that takes account of the Fermi resonance and inhomogeneity of the OH stretch vibration, and the simulated spectra reproduce the essential features of the 2D HD-VSFG spectra of the CTAB/H{sub 2}O interface. The present study demonstrates that heterodyne detection of the time-resolved VSFG is critically important for studying the ultrafast dynamics of water interfaces and for unveiling the underlying mechanism.

  2. Lithium Ion Solvation and Diffusion in Bulk Organic Electrolytes from First

    Office of Scientific and Technical Information (OSTI)

    Principles Molecular Dynamics (Conference) | SciTech Connect Lithium Ion Solvation and Diffusion in Bulk Organic Electrolytes from First Principles Molecular Dynamics Citation Details In-Document Search Title: Lithium Ion Solvation and Diffusion in Bulk Organic Electrolytes from First Principles Molecular Dynamics Authors: Ong, M T ; Lordi, V ; Draeger, E W ; Pask, J E Publication Date: 2014-11-05 OSTI Identifier: 1178391 Report Number(s): LLNL-PROC-663811 DOE Contract Number:

  3. Lithium Ion Solvation and Diffusion in Bulk Organic Electrolytes from First

    Office of Scientific and Technical Information (OSTI)

    Principles and Classical Reactive Molecular Dynamics (Journal Article) | SciTech Connect Journal Article: Lithium Ion Solvation and Diffusion in Bulk Organic Electrolytes from First Principles and Classical Reactive Molecular Dynamics Citation Details In-Document Search Title: Lithium Ion Solvation and Diffusion in Bulk Organic Electrolytes from First Principles and Classical Reactive Molecular Dynamics Authors: Ong, M T ; Verners, O ; Draeger, E W ; van Duin, A ; Lordi, V ; Pask, J E

  4. Lithium Ion Solvation and Diffusion in Bulk Organic Electrolytes from First

    Office of Scientific and Technical Information (OSTI)

    Principles and Classical Reactive Molecular Dynamics (Journal Article) | SciTech Connect Journal Article: Lithium Ion Solvation and Diffusion in Bulk Organic Electrolytes from First Principles and Classical Reactive Molecular Dynamics Citation Details In-Document Search Title: Lithium Ion Solvation and Diffusion in Bulk Organic Electrolytes from First Principles and Classical Reactive Molecular Dynamics × You are accessing a document from the Department of Energy's (DOE) SciTech Connect.

  5. Ultrafast Transformations in Superionic Nanocrystals

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Ultrafast Transformations in Superionic Nanocrystals Print A superionic material is a multi-component solid with simultaneous characteristics of both a solid and a liquid. Above a critical temperature associated with a structural phase transition, one of the atomic species in the material will exhibit liquid-like ionic conductivity and dynamic disorder within the rigid crystalline structure of the other. Discovered by Michael Faraday almost 200 years ago, superionic materials today hold promise

  6. Ultrafast Transformations in Superionic Nanocrystals

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Ultrafast Transformations in Superionic Nanocrystals Print A superionic material is a multi-component solid with simultaneous characteristics of both a solid and a liquid. Above a critical temperature associated with a structural phase transition, one of the atomic species in the material will exhibit liquid-like ionic conductivity and dynamic disorder within the rigid crystalline structure of the other. Discovered by Michael Faraday almost 200 years ago, superionic materials today hold promise

  7. Ultrafast Transformations in Superionic Nanocrystals

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Ultrafast Transformations in Superionic Nanocrystals Print A superionic material is a multi-component solid with simultaneous characteristics of both a solid and a liquid. Above a critical temperature associated with a structural phase transition, one of the atomic species in the material will exhibit liquid-like ionic conductivity and dynamic disorder within the rigid crystalline structure of the other. Discovered by Michael Faraday almost 200 years ago, superionic materials today hold promise

  8. Ultrafast Transformations in Superionic Nanocrystals

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Ultrafast Transformations in Superionic Nanocrystals Print A superionic material is a multi-component solid with simultaneous characteristics of both a solid and a liquid. Above a critical temperature associated with a structural phase transition, one of the atomic species in the material will exhibit liquid-like ionic conductivity and dynamic disorder within the rigid crystalline structure of the other. Discovered by Michael Faraday almost 200 years ago, superionic materials today hold promise

  9. Ultrafast Transformations in Superionic Nanocrystals

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Ultrafast Transformations in Superionic Nanocrystals Print A superionic material is a multi-component solid with simultaneous characteristics of both a solid and a liquid. Above a critical temperature associated with a structural phase transition, one of the atomic species in the material will exhibit liquid-like ionic conductivity and dynamic disorder within the rigid crystalline structure of the other. Discovered by Michael Faraday almost 200 years ago, superionic materials today hold promise

  10. Ultrafast Transformations in Superionic Nanocrystals

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Ultrafast Transformations in Superionic Nanocrystals Print A superionic material is a multi-component solid with simultaneous characteristics of both a solid and a liquid. Above a critical temperature associated with a structural phase transition, one of the atomic species in the material will exhibit liquid-like ionic conductivity and dynamic disorder within the rigid crystalline structure of the other. Discovered by Michael Faraday almost 200 years ago, superionic materials today hold promise

  11. Structure, solvation, and dynamics of Mg{sup 2+}, Ca{sup 2+}, Sr{sup 2+}, and Ba{sup 2+} complexes with 3-hydroxyflavone and perchlorate anion in acetonitrile medium: A molecular dynamics simulation study

    SciTech Connect (OSTI)

    Agieienko, Vira N.; Kolesnik, Yaroslav V.; Kalugin, Oleg N.

    2014-05-21

    Molecular dynamics simulations of complexes of Mg{sup 2+}, Ca{sup 2+}, Sr{sup 2+}, and Ba{sup 2+} with 3-hydroxyflavone (flavonol, 3HF) and ClO {sub 4}{sup ?} in acetonitrile were performed. The united atoms force field model was proposed for the 3HF molecule using the results of DFT quantum chemical calculations. 3HF was interpreted as a rigid molecule with two internal degrees of freedom, i.e., rotation of the phenyl ring and of the OH group with respect to the chromone moiety. The interatomic radial distribution functions showed that interaction of the cations with flavonol occurs via the carbonyl group of 3HF and it is accompanied with substitution of one of the acetonitrile molecules in the cations first solvation shells. Formation of the cation3HF complexes does not have significant impact on the rotation of the phenyl ring with respect to the chromone moiety. However, the orientation of the flavonol's OH-group is more sensitive to the interaction with doubly charged cations. When complex with Mg{sup 2+} is formed, the OH-group turns out of the plane of the chromone moiety that leads to rupture of intramolecular H-bond in the ligand molecule. Complexation of Ca{sup 2+}, Sr{sup 2+}, and BaClO {sub 4}{sup +} with 3HF produces two structures with different OH-positions, as in the free flavonol with the intramolecular H-bond and as in the complex with Mg{sup 2+} with disrupted H-bonding. It was shown that additional stabilization of the [MgClO{sub 4}(3HF)]{sup +} and [BaClO{sub 4}(3HF)]{sup +} complexes is determined by strong affinity of perchlorate anion to interact with flavonol via intracomplex hydrogen bond between an oxygen atom of the anion and the hydrogen atom of the 3-hydroxyl group. Noticeable difference in the values of the self-diffusion coefficients for Kt{sup 2+} from one side and ClO {sub 4}{sup ?}, 3HF, and AN in the cations coordination shell from another side implies quite weak interaction between cation, anion, and ligands in the investigated complexes.

  12. Ultrafast spin exchange-coupling torque via photo-excited charge-transfer

    Office of Scientific and Technical Information (OSTI)

    processes (Journal Article) | DOE PAGES Accepted Manuscript: Ultrafast spin exchange-coupling torque via photo-excited charge-transfer processes Title: Ultrafast spin exchange-coupling torque via photo-excited charge-transfer processes In this study, optical control of spin is of central importance in the research of ultrafast spintronic devices utilizing spin dynamics at short time scales. Recently developed optical approaches such as ultrafast demagnetization, spin-transfer and spin-orbit

  13. Ultrafast spin exchange-coupling torque via photo-excited charge-transfer

    Office of Scientific and Technical Information (OSTI)

    processes (Journal Article) | SciTech Connect Ultrafast spin exchange-coupling torque via photo-excited charge-transfer processes Citation Details In-Document Search Title: Ultrafast spin exchange-coupling torque via photo-excited charge-transfer processes In this study, optical control of spin is of central importance in the research of ultrafast spintronic devices utilizing spin dynamics at short time scales. Recently developed optical approaches such as ultrafast demagnetization,

  14. Preparation of cerium halide solvate complexes

    DOE Patents [OSTI]

    Vasudevan, Kalyan V; Smith, Nickolaus A; Gordon, John C; McKigney, Edward A; Muenchaussen, Ross E

    2013-08-06

    Crystals of a solvated cerium(III) halide solvate complex resulted from a process of forming a paste of a cerium(III) halide in an ionic liquid, adding a solvent to the paste, removing any undissolved solid, and then cooling the liquid phase. Diffusing a solvent vapor into the liquid phase also resulted in crystals of a solvated cerium(III) halide complex.

  15. Indirect excitation of ultrafast demagnetization

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Vodungbo, Boris; Tudu, Bahrati; Perron, Jonathan; Delaunay, Renaud; Müller, Leonard; Berntsen, Magnus H.; Grübel, Gerhard; Malinowski, Grégory; Weier, Christian; Gautier, Julien; et al

    2016-01-06

    Does the excitation of ultrafast magnetization require direct interaction between the photons of the optical pump pulse and the magnetic layer? Here, we demonstrate unambiguously that this is not the case. For this we have studied the magnetization dynamics of a ferromagnetic cobalt/palladium multilayer capped by an IR-opaque aluminum layer. Upon excitation with an intense femtosecond-short IR laser pulse, the film exhibits the classical ultrafast demagnetization phenomenon although only a negligible number of IR photons penetrate the aluminum layer. In comparison with an uncapped cobalt/palladium reference film, the initial demagnetization of the capped film occurs with a delayed onset andmore » at a slower rate. Both observations are qualitatively in line with energy transport from the aluminum layer into the underlying magnetic film by the excited, hot electrons of the aluminum film. As a result, our data thus confirm recent theoretical predictions.« less

  16. Excited state carrier dynamics in CdS{sub x}Se{sub 1-x} semisconductor alloys as studied by ultrafast fluorescence spectroscopy

    SciTech Connect (OSTI)

    Gadd, S.E.

    1995-08-01

    This dissertation discusses studies of the electron-hole pair dynamics of CdS{sub x}Se{sub 1-x} semiconductor alloys for the entire compositional range from x = 1 to x = 0 as examined by the ultrafast fluorescence techniques of time correlated single photon counting and fluorescence upconversion. Specifically, samples with x = 1, .75, .5, .25, and 0 were studied each at a spread of wavelengths about its respective emission maximum which varies according to {lambda} = 718nm - 210x nm. The decays of these samples were found to obey a Kohlrausch distribution, exp [(t/{tau}){sup {beta}}], with the exponent 3 in the range .5-.7 for the alloys. These results are in agreement with those expected for localization due to local potential variations resulting from the random distribution of sulfur and selenium atoms on the element VI A sub-lattice. This localization can be understood in terms of Anderson localization of the holes in states whose energy distribution tails into the forbidden energy band-gap. Because these states have energy dependent lifetimes, the carriers can decay via many parallel channels. This distribution of channels is the ultimate source of the Kohlrausch form of the fluorescence decays.

  17. Ultrafast dynamics of strong-field dissociative ionization ofCH2Br2 probed by femtosecond soft x-ray transient absorptionspectroscopy

    SciTech Connect (OSTI)

    Loh, Zhi-Heng; Leone, Stephen R.

    2008-01-15

    Femtosecond time-resolved soft x-ray transient absorption spectroscopy based on a high-order harmonic generation source is used to investigate the dissociative ionization of CH{sub 2}Br{sub 2} induced by 800 nm strong-field irradiation. At moderate peak intensities (2.0 x 10{sup 14} W/cm{sup 2}), strong-field ionization is accompanied by ultrafast C-Br bond dissociation, producing both neutral Br ({sup 2}P{sub 3/2}) and Br* ({sup 2}P{sub 1/2}) atoms together with the CH{sub 2}Br{sup +} fragment ion. The measured rise times for Br and Br* are 130 {+-} 22 fs and 74 {+-} 10 fs, respectively. The atomic bromine quantum state distribution shows that the Br/Br* population ratio is 8.1 {+-} 3.8 and that the Br {sup 2}P{sub 3/2} state is not aligned. The observed product distribution and the timescales of the photofragment appearances suggest that multiple field-dressed potential energy surfaces are involved in the dissociative ionization process. In addition, the transient absorption spectrum of CH{sub 2}Br{sub 2}{sup +} suggests that the alignment of the molecule relative to the polarization axis of the strong-field ionizing pulse determines the electronic symmetry of the resulting ion; alignment of the Br-Br, H-H, and C{sub 2} axis of the molecule along the polarization axis results in the production of the ion {tilde X}({sup 2}B{sub 2}), {tilde B}({sup 2}B{sub 1}) and {tilde C}({sup 2}A{sub 1}) states, respectively. At higher peak intensities (6.2 x 10{sup 14} W/cm{sup 2}), CH{sub 2}Br{sub 2}{sup +} undergoes sequential ionization to form the metastable CH{sub 2}Br{sub 2}{sup 2+} dication. These results demonstrate the potential of core-level probing with high-order harmonic transient absorption spectroscopy for studying ultrafast molecular dynamics.

  18. Indirect excitation of ultrafast demagnetization (Journal Article...

    Office of Scientific and Technical Information (OSTI)

    Indirect excitation of ultrafast demagnetization Citation Details In-Document Search Title: Indirect excitation of ultrafast demagnetization Does the excitation of ultrafast ...

  19. Electrolyte Solvation and Ionic Association. V. Acetonitrile...

    Office of Scientific and Technical Information (OSTI)

    V. Acetonitrile-Lithium Bis(fluorosulfonyl)imide (LiFSI) Mixtures Citation Details In-Document Search Title: Electrolyte Solvation and Ionic Association. V. Acetonitrile-Lithium ...

  20. Ultrafast Photovoltaic Response in Ferroelectric Nanolayers ...

    Office of Scientific and Technical Information (OSTI)

    Ultrafast Photovoltaic Response in Ferroelectric Nanolayers Citation Details In-Document Search Title: Ultrafast Photovoltaic Response in Ferroelectric Nanolayers Authors:...

  1. Final Progress Report for Linking Ion Solvation and Lithium Battery

    Office of Scientific and Technical Information (OSTI)

    for Linking Ion Solvation and Lithium Battery Electrolyte Properties Henderson, Wesley 25 ENERGY STORAGE battery, electrolyte, solvation, ionic association battery, electrolyte,...

  2. Imaging the ultrafast Kerr effect, free carrier generation, relaxation and ablation dynamics of Lithium Niobate irradiated with femtosecond laser pulses

    SciTech Connect (OSTI)

    Garcia-Lechuga, Mario, E-mail: mario@io.cfmac.csic.es; Siegel, Jan, E-mail: j.siegel@io.cfmac.csic.es; Hernandez-Rueda, Javier; Solis, Javier [Laser Processing Group, Instituto de Optica, CSIC, Serrano 121, 28006 Madrid (Spain)

    2014-09-21

    The interaction of high-power single 130 femtosecond (fs) laser pulses with the surface of Lithium Niobate is experimentally investigated in this work. The use of fs-resolution time-resolved microscopy allows us to separately observe the instantaneous optical Kerr effect induced by the pulse and the generation of a free electron plasma. The maximum electron density is reached 550 fs after the peak of the Kerr effect, confirming the presence of a delayed carrier generation mechanism. We have also observed the appearance of transient Newton rings during the ablation process, related to optical interference of the probe beam reflected at the front and back surface of the ablating layer. Finally, we have analyzed the dynamics of the photorefractive effect on a much longer time scale by measuring the evolution of the transmittance of the irradiated area for different fluences below the ablation threshold.

  3. Electronic Coupling Dependence of Ultrafast Interfacial Electron Transfer

    Office of Scientific and Technical Information (OSTI)

    on Nanocrystalline Thin Films and Single Crystal (Technical Report) | SciTech Connect Electronic Coupling Dependence of Ultrafast Interfacial Electron Transfer on Nanocrystalline Thin Films and Single Crystal Citation Details In-Document Search Title: Electronic Coupling Dependence of Ultrafast Interfacial Electron Transfer on Nanocrystalline Thin Films and Single Crystal The long-term goal of the proposed research is to understand electron transfer dynamics in nanoparticle/liquid interface.

  4. Structural Interactions within Lithium Salt Solvates: Acyclic Carbonates

    Office of Scientific and Technical Information (OSTI)

    and Esters (Journal Article) | SciTech Connect Structural Interactions within Lithium Salt Solvates: Acyclic Carbonates and Esters Citation Details In-Document Search Title: Structural Interactions within Lithium Salt Solvates: Acyclic Carbonates and Esters Solvate crystal structures serve as useful models for the molecular-level interactions within the diverse solvates present in liquid electrolytes. Although acyclic carbonate solvents are widely used for Li-ion battery electrolytes, only

  5. Reactions of Solvated Ions Final Report

    DOE R&D Accomplishments [OSTI]

    Taube, H.

    1962-09-24

    Brief summaries are presented on isotopic dilution studies on salts dissolved in CH{sub 3}OH, studies on metal and metal salts in solvents of the amine type, and studies on phosphato complexes of the pentammine Co(III) series. A list of papers published on reactions of solvated ions is included. (N.W.R.)

  6. Quasiparticle dynamics across the full Brillouin zone of Bi2Sr2CaCu2O8+δ traced with ultrafast time and angle-resolved photoemission spectroscopy

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Dakovski, Georgi L.; Durakiewicz, Tomasz; Zhu, Jian-Xin; Riseborough, Peter S.; Gu, Genda; Gilbertson, Steve M.; Taylor, Antoinette; Rodriguez, George

    2015-10-12

    A hallmark in the cuprate family of high-temperature superconductors is the nodal-antinodal dichotomy. In this regard, angle-resolved photoemission spectroscopy (ARPES) has proven especially powerful, providing band structure information directly in energy-momentum space. Time-resolved ARPES (trARPES) holds great promise of adding ultrafast temporal information, in an attempt to identify different interaction channels in the time domain. Previous studies of the cuprates using trARPES were handicapped by the low probing energy which significantly limits the accessible momentum space. Using 20.15eV, 12 fs pulses we show for the first time the evolution of quasiparticles in the antinodal region of Bi2Sr2CaCu2O8+δ and demonstrate thatmore »nonmonotonic relaxation dynamics dominates above a certain fluence threshold. The dynamics is heavily influenced by transient modification of the electron-phonon interaction and phase space restrictions, in severe contrast to the monotonic relaxation in the nodal and off-nodal regions.« less

  7. Quasiparticle dynamics across the full Brillouin zone of Bi2Sr2CaCu2O8+δ traced with ultrafast time and angle-resolved photoemission spectroscopy

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Dakovski, Georgi L.; Durakiewicz, Tomasz; Zhu, Jian-Xin; Riseborough, Peter S.; Gu, Genda; Gilbertson, Steve M.; Taylor, Antoinette; Rodriguez, George

    2015-10-12

    A hallmark in the cuprate family of high-temperature superconductors is the nodal-antinodal dichotomy. In this regard, angle-resolved photoemission spectroscopy (ARPES) has proven especially powerful, providing band structure information directly in energy-momentum space. Time-resolved ARPES (trARPES) holds great promise of adding ultrafast temporal information, in an attempt to identify different interaction channels in the time domain. Previous studies of the cuprates using trARPES were handicapped by the low probing energy which significantly limits the accessible momentum space. Using 20.15eV, 12 fs pulses we show for the first time the evolution of quasiparticles in the antinodal region of Bi2Sr2CaCu2O8+δ and demonstrate thatmore » nonmonotonic relaxation dynamics dominates above a certain fluence threshold. The dynamics is heavily influenced by transient modification of the electron-phonon interaction and phase space restrictions, in severe contrast to the monotonic relaxation in the nodal and off-nodal regions.« less

  8. Ultrafast Probes for Dirac Materials Yarotski, Dmitry Anatolievitch...

    Office of Scientific and Technical Information (OSTI)

    Science(36) Material Science; topological insulators, ultrafast spectroscopy, graphene Material Science; topological insulators, ultrafast spectroscopy, graphene Abstract...

  9. Patent: Ultrafast transient grating radiation to optical image...

    Office of Scientific and Technical Information (OSTI)

    Ultrafast transient grating radiation to optical image converter Citation Details Title: Ultrafast transient grating radiation to optical image converter...

  10. Ultrafast spin exchange-coupling torque via photo-excited charge-transfer processes

    Office of Scientific and Technical Information (OSTI)

    8 Jun 2015 | Accepted 5 Oct 2015 | Published 28 Oct 2015 DOI: 10.1038/ncomms9800 OPEN Ultrafast spin exchange-coupling torque via photo-excited charge-transfer processes X. Ma1, F. Fang1, Q. Li2, J. Zhu2, Y. Yang2, Y.Z. Wu2, H.B. Zhao3 & G. Lupke1 Optical control of spin is of central importance in the research of ultrafast spintronic devices utilizing spin dynamics at short time scales. Recently developed optical approaches such as ultrafast demagnetization, spin-transfer and spin-orbit

  11. Ultrafast Structural Rearrangements in the MLCT Excited State for Copper(I)

    Office of Scientific and Technical Information (OSTI)

    bis-Phenanthrolines in Solution (Journal Article) | SciTech Connect Ultrafast Structural Rearrangements in the MLCT Excited State for Copper(I) bis-Phenanthrolines in Solution Citation Details In-Document Search Title: Ultrafast Structural Rearrangements in the MLCT Excited State for Copper(I) bis-Phenanthrolines in Solution Ultrafast excited state structural dynamics of [Cu{sup I}(dmp){sub 2}]{sup +} (dmp = 2,9-dimethyl-1,10-phenanthroline) have been studied to identify structural origins

  12. Final Progress Report for Linking Ion Solvation and Lithium Battery

    Office of Scientific and Technical Information (OSTI)

    Electrolyte Properties (Technical Report) | SciTech Connect Technical Report: Final Progress Report for Linking Ion Solvation and Lithium Battery Electrolyte Properties Citation Details In-Document Search Title: Final Progress Report for Linking Ion Solvation and Lithium Battery Electrolyte Properties The research objective of this proposal was to provide a detailed analysis of how solvent and anion structure govern the solvation state of Li+ cations in solvent-LiX mixtures and how this, in

  13. Final Progress Report for Linking Ion Solvation and Lithium Battery

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Electrolyte Properties (Technical Report) | SciTech Connect Progress Report for Linking Ion Solvation and Lithium Battery Electrolyte Properties Citation Details In-Document Search Title: Final Progress Report for Linking Ion Solvation and Lithium Battery Electrolyte Properties The research objective of this proposal was to provide a detailed analysis of how solvent and anion structure govern the solvation state of Li+ cations in solvent-LiX mixtures and how this, in turn, dictates the

  14. Competitive lithium solvation of linear and cyclic carbonates from quantum chemistry

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Kent, Paul R. C.; Ganesh, Panchapakesan; Borodin, Oleg; Olguin, Marco; Allen, Joshua L.; Henderson, Wesley A.

    2015-11-17

    The composition of the lithium cation (Li+) solvation shell in mixed linear and cyclic carbonate-based electrolytes has been re-examined using Born–Oppenheimer molecular dynamics (BOMD) as a function of salt concentration and cluster calculations with ethylene carbonate:dimethyl carbonate (EC:DMC)–LiPF6 as a model system. A coordination preference for EC over DMC to a Li+ was found at low salt concentrations, while a slightly higher preference for DMC over EC was found at high salt concentrations. Analysis of the relative binding energies of the (EC)n(DMC)m–Li+ and (EC)n(DMC)m–LiPF6 solvates in the gas-phase and for an implicit solvent (as a function of the solvent dielectricmore » constant) indicated that the DMC-containing Li+ solvates were stabilized relative to (EC4)–Li+ and (EC)3–LiPF6 by immersing them in the implicit solvent. Such stabilization was more pronounced in the implicit solvents with a high dielectric constant. Results from previous Raman and IR experiments were reanalyzed and reconciled by correcting them for changes of the Raman activities, IR intensities and band shifts for the solvents which occur upon Li+ coordination. After these correction factors were applied to the results of BOMD simulations, the composition of the Li+ solvation shell from the BOMD simulations was found to agree well with the solvation numbers extracted from Raman experiments. Finally, the mechanism of the Li+ diffusion in the dilute (EC:DMC)LiPF6 mixed solvent electrolyte was studied using the BOMD simulations.« less

  15. Ultrafast scanning probe microscopy

    DOE Patents [OSTI]

    Weiss, S.; Chemla, D.S.; Ogletree, D.F.; Botkin, D.

    1995-05-16

    An ultrafast scanning probe microscopy method is described for achieving subpicosecond-temporal resolution and submicron-spatial resolution of an observation sample. In one embodiment of the present claimed invention, a single short optical pulse is generated and is split into first and second pulses. One of the pulses is delayed using variable time delay means. The first pulse is then directed at an observation sample located proximate to the probe of a scanning probe microscope. The scanning probe microscope produces probe-sample signals indicative of the response of the probe to characteristics of the sample. The second pulse is used to modulate the probe of the scanning probe microscope. The time delay between the first and second pulses is then varied. The probe-sample response signal is recorded at each of the various time delays created between the first and second pulses. The probe-sample response signal is then plotted as a function of time delay to produce a cross-correlation of the probe sample response. In so doing, the present invention provides simultaneous subpicosecond-temporal resolution and submicron-spatial resolution of the sample. 6 Figs.

  16. Ultrafast scanning probe microscopy

    DOE Patents [OSTI]

    Weiss, Shimon (El Cerrito, CA); Chemla, Daniel S. (Kensington, CA); Ogletree, D. Frank (El Cerrito, CA); Botkin, David (San Francisco, CA)

    1995-01-01

    An ultrafast scanning probe microscopy method for achieving subpicosecond-temporal resolution and submicron-spatial resolution of an observation sample. In one embodiment of the present claimed invention, a single short optical pulse is generated and is split into first and second pulses. One of the pulses is delayed using variable time delay means. The first pulse is then directed at an observation sample located proximate to the probe of a scanning probe microscope. The scanning probe microscope produces probe-sample signals indicative of the response of the probe to characteristics of the sample. The second pulse is used to modulate the probe of the scanning probe microscope. The time delay between the first and second pulses is then varied. The probe-sample response signal is recorded at each of the various time delays created between the first and second pulses. The probe-sample response signal is then plotted as a function of time delay to produce a cross-correlation of the probe sample response. In so doing, the present invention provides simultaneous subpicosecond-temporal resolution and submicron-spatial resolution of the sample.

  17. Preferential solvation of lithium cations and impacts on oxygen reduction in lithiumair batteries

    SciTech Connect (OSTI)

    Zheng, Dong; Qu, Deyu; Yang, Xiao -Qing; Lee, Hung -Sui; Qu, Deyang

    2015-09-16

    The solvation of Li? with eleven non-aqueous solvents commonly used as the electrolytes for Li batteries were studied. The solvation preferences of different solvents were compared by means of electrospray mass spectrometry and collision-induced dissociation. The relative strength of the solvent for the solvation of Li? was determined. The Lewis acidity of the solvated Li? cations was determined by the preferential solvation of the solvent in the solvation shell. The kinetics of the catalytic disproportionation of the O?? depends on the relative Lewis acidity of the solvated Li? ion. The impact of the solvated Li? cation on the O? redox reaction was also investigated.

  18. Ultrafast X-Ray Coherent Control

    SciTech Connect (OSTI)

    Reis, David

    2009-05-01

    This main purpose of this grant was to develop the nascent #12;eld of ultrafast x-ray science using accelerator-based sources, and originally developed from an idea that a laser could modulate the di#11;racting properties of a x-ray di#11;racting crystal on a fast enough time scale to switch out in time a shorter slice from the already short x-ray pulses from a synchrotron. The research was carried out primarily at the Advanced Photon Source (APS) sector 7 at Argonne National Laboratory and the Sub-Picosecond Pulse Source (SPPS) at SLAC; in anticipation of the Linac Coherent Light Source (LCLS) x-ray free electron laser that became operational in 2009 at SLAC (all National User Facilities operated by BES). The research centered on the generation, control and measurement of atomic-scale dynamics in atomic, molecular optical and condensed matter systems with temporal and spatial resolution . It helped develop the ultrafast physics, techniques and scienti#12;c case for using the unprecedented characteristics of the LCLS. The project has been very successful with results have been disseminated widely and in top journals, have been well cited in the #12;eld, and have laid the foundation for many experiments being performed on the LCLS, the world's #12;rst hard x-ray free electron laser.

  19. Ultrafast free-carrier dynamics in Cu{sub 2}ZnSnS{sub 4} single crystals studied using femtosecond time-resolved optical spectroscopy

    SciTech Connect (OSTI)

    Phuong, L. Q.; Kanemitsu, Y.; Okano, M.; Yamada, Y.; Yamashita, G.; Morimoto, T.; Nagai, M.; Ashida, M.; Nagaoka, A.; Yoshino, K.

    2014-12-08

    We studied the dynamics of photogenerated carriers in Cu{sub 2}ZnSnS{sub 4} (CZTS) single crystals using femtosecond transient reflectivity (TR) and optical pump-THz probe transient absorption (THz-TA) spectroscopy. The TR and THz-TA decay dynamics consistently showed that free carriers have long lifetimes of up to a few nanoseconds. The excitation-photon-energy-dependent TR measurements revealed a slow picosecond energy relaxation of free carriers to the band edge in CZTS. The relaxation and recombination dynamics of free carriers were affected by nonradiative recombinations at the surface. Our results revealed a global feature of energy relaxation and recombination processes of free carriers in CZTS single crystals.

  20. Solvate Structures and Computational/Spectroscopic Characterization of

    Office of Scientific and Technical Information (OSTI)

    LiBF4 Electrolytes (Journal Article) | SciTech Connect Solvate Structures and Computational/Spectroscopic Characterization of LiBF4 Electrolytes Citation Details In-Document Search Title: Solvate Structures and Computational/Spectroscopic Characterization of LiBF4 Electrolytes Crystal structures have been determined for both LiBF4 and HBF4 solvates-(acetonitrile)2:LiBF4, (ethylene glycol diethyl ether)1:LiBF4, (diethylene glycol diethyl ether)1:LiBF4, (tetrahydrofuran)1:LiBF4, (methyl

  1. Ultrafast Laser Fabrication: a Rapid Prototyping Capability for...

    Office of Scientific and Technical Information (OSTI)

    Technical Report: Ultrafast Laser Fabrication: a Rapid Prototyping Capability for CINT Citation Details In-Document Search Title: Ultrafast Laser Fabrication: a Rapid Prototyping...

  2. Ultrafast Laser Diagnostics to Investigate Initiation in Energetic...

    Office of Scientific and Technical Information (OSTI)

    Ultrafast Laser Diagnostics to Investigate Initiation in Energetic Materials. Citation Details In-Document Search Title: Ultrafast Laser Diagnostics to Investigate Initiation in...

  3. Ultrafast Laser Diagnostics for Studies of Shock Initiation in...

    Office of Scientific and Technical Information (OSTI)

    Ultrafast Laser Diagnostics for Studies of Shock Initiation in Energetic Materials. Citation Details In-Document Search Title: Ultrafast Laser Diagnostics for Studies of Shock ...

  4. Patent: Ultrafast chirped optical waveform recorder using a time microscope

    Office of Scientific and Technical Information (OSTI)

    | DOEpatents Ultrafast chirped optical waveform recorder using a time microscope Citation Details Title: Ultrafast chirped optical waveform recorder using a time microscope

  5. Ultrafast Shock Initiation of Exothermic Chemistry in Hydrogen...

    Office of Scientific and Technical Information (OSTI)

    Journal Article: Ultrafast Shock Initiation of Exothermic Chemistry in Hydrogen Peroxide Citation Details In-Document Search Title: Ultrafast Shock Initiation of Exothermic...

  6. Ultrafast Laser Fabrication: a Rapid Prototyping Capability for...

    Office of Scientific and Technical Information (OSTI)

    Technical Report: Ultrafast Laser Fabrication: a Rapid Prototyping Capability for CINT Citation Details In-Document Search Title: Ultrafast Laser Fabrication: a Rapid Prototyping ...

  7. Ultrafast Structural Rearrangements in the MLCT Excited State...

    Office of Scientific and Technical Information (OSTI)

    Ultrafast Structural Rearrangements in the MLCT Excited State for Copper(I) bis-Phenanthrolines in Solution Citation Details In-Document Search Title: Ultrafast Structural...

  8. Ultrafast charge localization in a stripe-phase nickelate (Journal...

    Office of Scientific and Technical Information (OSTI)

    Journal Article: Ultrafast charge localization in a stripe-phase nickelate Citation Details In-Document Search Title: Ultrafast charge localization in a stripe-phase nickelate ...

  9. Ultrafast Optical Microscopy of Single Monolayer Molybdenum Disulfide...

    Office of Scientific and Technical Information (OSTI)

    Ultrafast Optical Microscopy of Single Monolayer Molybdenum Disulfide Flakes Citation Details In-Document Search Title: Ultrafast Optical Microscopy of Single Monolayer Molybdenum ...

  10. Surface modified CFx cathode material for ultrafast discharge...

    Office of Scientific and Technical Information (OSTI)

    Surface modified CFx cathode material for ultrafast discharge and high energy density Prev Next Title: Surface modified CFx cathode material for ultrafast discharge and high...

  11. Ultrafast Laser Facility - Virtual Tour | Photosynthetic Antenna...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    a virtual tour of the Ultrafast Laser Facility for St. Louis University High School students. Special thanks to teacher Nhan Pham for joining us An error occurred. Try...

  12. Ultrafast Laser Facility | Photosynthetic Antenna Research Center

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Ultrafast Laser Facility, under the direction of Associate Director and Theme 3 Leader Dewey Holten, utilizes four integrated state-of-the-art instruments to probe diverse natural...

  13. Cavity-Enhanced Transient Absorption Spectroscopy: Ultrafast...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Cavity-Enhanced Transient Absorption Spectroscopy: Ultrafast Spectroscopy goes Ultra-Sensitive Wednesday, November 11, 2015 - 3:00pm SLAC, Redtail Hawk Conference Room 108A...

  14. Structural Interactions within Lithium Salt Solvates: Acyclic Carbonates and Esters

    SciTech Connect (OSTI)

    Afroz, Taliman; Seo, D. M.; Han, Sang D.; Boyle, Paul D.; Henderson, Wesley A.

    2015-03-06

    Solvate crystal structures serve as useful models for the molecular-level interactions within the diverse solvates present in liquid electrolytes. Although acyclic carbonate solvents are widely used for Li-ion battery electrolytes, only three solvate crystal structures with lithium salts are known for these and related solvents. The present work, therefore, reports six lithium salt solvate structures with dimethyl and diethyl carbonate: (DMC)2:LiPF6, (DMC)1:LiCF3SO3, (DMC)1/4:LiBF4, (DEC)2:LiClO4, (DEC)1:LiClO4 and (DEC)1:LiCF3SO3 and four with the structurally related methyl and ethyl acetate: (MA)2:LiClO4, (MA)1:LiBF4, (EA)1:LiClO4 and (EA)1:LiBF4.

  15. Ionic strength independence of charge distributions in solvation of biomolecules

    SciTech Connect (OSTI)

    Virtanen, J. J.; Sosnick, T. R.; Freed, K. F.

    2014-12-14

    Electrostatic forces enormously impact the structure, interactions, and function of biomolecules. We perform all-atom molecular dynamics simulations for 5 proteins and 5 RNAs to determine the dependence on ionic strength of the ion and water charge distributions surrounding the biomolecules, as well as the contributions of ions to the electrostatic free energy of interaction between the biomolecule and the surrounding salt solution (for a total of 40 different biomolecule/solvent combinations). Although water provides the dominant contribution to the charge density distribution and to the electrostatic potential even in 1M NaCl solutions, the contributions of water molecules and of ions to the total electrostatic interaction free energy with the solvated biomolecule are comparable. The electrostatic biomolecule/solvent interaction energies and the total charge distribution exhibit a remarkable insensitivity to salt concentrations over a huge range of salt concentrations (20 mM to 1M NaCl). The electrostatic potentials near the biomolecule's surface obtained from the MD simulations differ markedly, as expected, from the potentials predicted by continuum dielectric models, even though the total electrostatic interaction free energies are within 11% of each other.

  16. Linking Ion Solvation and Lithium Battery Electrolyte Properties |

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Department of Energy Linking Ion Solvation and Lithium Battery Electrolyte Properties Linking Ion Solvation and Lithium Battery Electrolyte Properties 2010 DOE Vehicle Technologies and Hydrogen Programs Annual Merit Review and Peer Evaluation Meeting, June 7-11, 2010 -- Washington D.C. PDF icon es043_henderson_2010_p.pdf More Documents & Publications Inexpensive, Nonfluorinated (or Partially Fluorinated) Anions for Lithium Salts and Ionic Liquids for Lithium Battery Electrolytes

  17. Electrolyte Solvation and Ionic Association. V. Acetonitrile-Lithium

    Office of Scientific and Technical Information (OSTI)

    Bis(fluorosulfonyl)imide (LiFSI) Mixtures (Journal Article) | SciTech Connect Electrolyte Solvation and Ionic Association. V. Acetonitrile-Lithium Bis(fluorosulfonyl)imide (LiFSI) Mixtures Citation Details In-Document Search Title: Electrolyte Solvation and Ionic Association. V. Acetonitrile-Lithium Bis(fluorosulfonyl)imide (LiFSI) Mixtures Electrolytes with the salt lithium bis(fluorosulfonyl)imide (LiFSI) have been evaluated relative to comparable electrolytes with other lithium salts.

  18. Solvate Structures and Computational/Spectroscopic Characterization of

    Office of Scientific and Technical Information (OSTI)

    LiPF6 Electrolytes (Journal Article) | SciTech Connect Solvate Structures and Computational/Spectroscopic Characterization of LiPF6 Electrolytes Citation Details In-Document Search Title: Solvate Structures and Computational/Spectroscopic Characterization of LiPF6 Electrolytes Raman spectroscopy is a powerful method for identifying ion-ion interactions, but only if the vibrational band signature for the anion coordination modes can be accurately deciphered. The present study characterizes

  19. Ultrafast Optical Microscopy of Single Monolayer Molybdenum Disulfide Flakes

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Seo, Minah; Yamaguchi, Hisato; Mohite, Aditya D.; Boubanga-Tombet, Stephane; Blancon, Jean-Christophe; Najmaei, Sina; Ajayan, Pulickel M.; Lou, Jun; Taylor, Antoinette J.; Prasankumar, Rohit P.

    2016-02-15

    We performed ultrafast optical microscopy on single flakes of atomically thin CVD-grown molybdenum disulfide, using non-degenerate femtosecond pump-probe spectroscopy to excite and probe carriers above and below the indirect and direct band gaps. These measurements reveal the influence of layer thickness on carrier dynamics when probing near the band gap. Furthermore, fluence-dependent measurements indicate that carrier relaxation is primarily influenced by surface-related defect and trap states after above-bandgap photoexcitation. Furthermore, the ability to probe femtosecond carrier dynamics in individual flakes can thus give much insight into light-matter interactions in these two-dimensional nanosystems.

  20. Water-enhanced solvation of organics

    SciTech Connect (OSTI)

    Lee, J.H.

    1993-07-01

    Water-enhanced solvation (WES) was explored for Lewis acid solutes in Lewis base organic solvents, to develop cheap extract regeneration processes. WES for solid solutes was determined from ratios of solubilities of solutes in water-sat. and low-water solvent; both were determined from solid-liquid equilibrium. Vapor-headspace analysis was used to determine solute activity coefficients as function of organic phase water concentration. WES magnitudes of volatile solutes were normalized, set equal to slope of log {gamma}{sub s} vs x{sub w}/x{sub s} curve. From graph shape {Delta}(log {gamma}{sub s}) represents relative change in solute activity coefficient. Solutes investigated by vapor-headspace analysis were acetic acid, propionic acid, ethanol, 1,2-propylene glycol, 2,3-butylene glycol. Monocarboxylic acids had largest decrease in activity coefficient with water addition followed by glycols and alcohols. Propionic acid in cyclohexanone showed greatest water-enhancement {Delta} (log {gamma}{sub acid})/{Delta}(x{sub w}/x{sub acid}) = {minus}0.25. In methylcyclohexanone, the decrease of the activity coefficient of propionic acid was {minus}0.19. Activity coefficient of propionic acid in methylcyclohexanone stopped decreasing once the water reached a 2:1 water to acid mole ratio, implying a stoichiometric relation between water, ketone, and acid. Except for 2,3-butanediol, activity coefficients of the solutes studied decreased monotonically with water content. Activity coefficient curves of ethanol, 1,2-propanediol and 2,3-butanediol did not level off at large water/solute mole ratio. Solutes investigated by solid-liquid equilibrium were citric acid, gallic acid, phenol, xylenols, 2-naphthol. Saturation concentration of citric acid in anhydrous butyl acetate increased from 0.0009 to 0.087 mol/L after 1.3 % (g/g) water co-dissolved into organic phase. Effect of water-enhanced solvation for citric acid is very large but very small for phenol and its derivatives.

  1. Impact system for ultrafast synchrotron experiments

    SciTech Connect (OSTI)

    Jensen, B. J.; Owens, C. T.; Ramos, K. J.; Yeager, J. D.; Saavedra, R. A.; Luo, S. N.; Hooks, D. E.; Iverson, A. J.; Fezzaa, K.

    2013-01-15

    The impact system for ultrafast synchrotron experiments, or IMPULSE, is a 12.6-mm bore light-gas gun (<1 km/s projectile velocity) designed specifically for performing dynamic compression experiments using the advanced imaging and X-ray diffraction methods available at synchrotron sources. The gun system, capable of reaching projectile velocities up to 1 km/s, was designed to be portable for quick insertion/removal in the experimental hutch at Sector 32 ID-B of the Advanced Photon Source (Argonne, IL) while allowing the target chamber to rotate for sample alignment with the beam. A key challenge in using the gun system to acquire dynamic data on the nanosecond time scale was synchronization (or bracketing) of the impact event with the incident X-ray pulses (80 ps width). A description of the basic gun system used in previous work is provided along with details of an improved launch initiation system designed to significantly reduce the total system time from launch initiation to impact. Experiments were performed to directly measure the gun system time and to determine the gun performance curve for projectile velocities ranging from 0.3 to 0.9 km/s. All results show an average system time of 21.6 {+-} 4.5 ms, making it possible to better synchronize the gun system and detectors to the X-ray beam.

  2. Order and correlation contributions to the entropy of hydrophobic solvation

    SciTech Connect (OSTI)

    Liu, Maoyuan; Besford, Quinn Alexander; Mulvaney, Thomas; Gray-Weale, Angus

    2015-03-21

    The entropy of hydrophobic solvation has been explained as the result of ordered solvation structures, of hydrogen bonds, of the small size of the water molecule, of dispersion forces, and of solvent density fluctuations. We report a new approach to the calculation of the entropy of hydrophobic solvation, along with tests of and comparisons to several other methods. The methods are assessed in the light of the available thermodynamic and spectroscopic information on the effects of temperature on hydrophobic solvation. Five model hydrophobes in SPC/E water give benchmark solvation entropies via Widom’s test-particle insertion method, and other methods and models are tested against these particle-insertion results. Entropies associated with distributions of tetrahedral order, of electric field, and of solvent dipole orientations are examined. We find these contributions are small compared to the benchmark particle-insertion entropy. Competitive with or better than other theories in accuracy, but with no free parameters, is the new estimate of the entropy contributed by correlations between dipole moments. Dipole correlations account for most of the hydrophobic solvation entropy for all models studied and capture the distinctive temperature dependence seen in thermodynamic and spectroscopic experiments. Entropies based on pair and many-body correlations in number density approach the correct magnitudes but fail to describe temperature and size dependences, respectively. Hydrogen-bond definitions and free energies that best reproduce entropies from simulations are reported, but it is difficult to choose one hydrogen bond model that fits a variety of experiments. The use of information theory, scaled-particle theory, and related methods is discussed briefly. Our results provide a test of the Frank-Evans hypothesis that the negative solvation entropy is due to structured water near the solute, complement the spectroscopic detection of that solvation structure by identifying the structural feature responsible for the entropy change, and point to a possible explanation for the observed dependence on length scale. Our key results are that the hydrophobic effect, i.e. the signature, temperature-dependent, solvation entropy of nonpolar molecules in water, is largely due to a dispersion force arising from correlations between rotating permanent dipole moments, that the strength of this force depends on the Kirkwood g-factor, and that the strength of this force may be obtained exactly without simulation.

  3. Indirect excitation of ultrafast demagnetization

    Office of Scientific and Technical Information (OSTI)

    Indirect excitation of ultrafast demagnetization Boris Vodungbo1,2, Bahrati Tudu1,2, Jonathan Perron1,2, Renaud Delaunay1,2, Leonard Muller3, Magnus H. Berntsen3, Gerhard Grubel3,4, Gregory Malinowski5, Christian Weier6, Recelved: 03 September 2015 Julien Gautier7, Guillaume Lambert7, Philippe Zeitoun7, Christian Gutt8, Emmanuelle Jal9, Acce ted: 01 December 2015 Alexander H. Reid9, Patrick W. Granitzka9,10, Nicolas Jaouen11, Georgi L. Dakovski12, CCeP e : eCem er Stefan Moeller12, Michael P.

  4. Preferential solvation of lithium cations and impacts on oxygen reduction in lithium–air batteries

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Zheng, Dong; Qu, Deyu; Yang, Xiao -Qing; Lee, Hung -Sui; Qu, Deyang

    2015-09-16

    The solvation of Li⁺ with eleven non-aqueous solvents commonly used as the electrolytes for Li batteries were studied. The solvation preferences of different solvents were compared by means of electrospray mass spectrometry and collision-induced dissociation. The relative strength of the solvent for the solvation of Li⁺ was determined. The Lewis acidity of the solvated Li⁺ cations was determined by the preferential solvation of the solvent in the solvation shell. The kinetics of the catalytic disproportionation of the O₂⁻ depends on the relative Lewis acidity of the solvated Li⁺ ion. The impact of the solvated Li⁺ cation on the O₂ redoxmore » reaction was also investigated.« less

  5. Ultrafast carrier capture in InGaAs quantum posts

    SciTech Connect (OSTI)

    Talbayev, Diyar; Taylor, Antoinette J; Stehr, D; Morris, C M; Wagner, M; Kim, H C; Schneider, H; Petroff, P M; Sherwin, M S

    2009-01-01

    To explore the capture dynamics of photoexcited carriers in semiconductor quantum posts, optical pump - THz probe and time-resolved photoluminescence spectroscopy were performed. The results of the THz experiment show that after ultrafast excitation, electrons relax within a few picoseconds into the quantum posts, which are acting as efficient traps. The saturation of the quantum post states, probed by photoluminescence, was reached approximately at ten times the quantum post density in the samples. The results imply that quantum posts are posts highly attractive nanostructures for future device applications.

  6. SISGR: Linking Ion Solvation and Lithium Battery Electrolyte Properties

    SciTech Connect (OSTI)

    Trulove, Paul C; Foley, Matthew P

    2013-03-14

    The solvation and phase behavior of the model battery electrolyte salt lithium trifluoromethanesulfonate (LiCF3SO3) in commonly used organic solvents; ethylene carbonate (EC), gamma-butyrolactone (GBL), and propylene carbonate (PC) was explored. Data from differential scanning calorimetry (DSC), Raman spectroscopy, and X-ray diffraction were correlated to provide insight into the solvation states present within a sample mixture. Data from DSC analyses allowed the construction of phase diagrams for each solvent system. Raman spectroscopy enabled the determination of specific solvation states present within a solvent-????salt mixture, and X-ray diffraction data provided exact information concerning the structure of a solvates that could be isolated Thermal analysis of the various solvent-salt mixtures revealed the phase behavior of the model electrolytes was strongly dependent on solvent symmetry. The point groups of the solvents were (in order from high to low symmetry): C2V for EC, CS for GBL, and C1 for PC(R). The low symmetry solvents exhibited a crystallinity gap that increased as solvent symmetry decreased; no gap was observed for EC-LiTf, while a crystallinity gap was observed spanning 0.15 to 0.3 mole fraction for GBL-LiTf, and 0.1 to 0.33 mole fraction for PC(R)-LiTf mixtures. Raman analysis demonstrated the dominance of aggregated species in almost all solvent compositions. The AGG and CIP solvates represent the majority of the species in solutions for the more concentrated mixtures, and only in very dilute compositions does the SSIP solvate exist in significant amounts. Thus, the poor charge transport characteristics of CIP and AGG account for the low conductivity and transport properties of LiTf and explain why is a poor choice as a source of Li+ ions in a Li-ion battery.

  7. Strong influence of coadsorbate interaction on CO desorption dynamics on

    Office of Scientific and Technical Information (OSTI)

    Ru(0001) probed by ultrafast x-ray spectroscopy and ab initio simulations (Journal Article) | SciTech Connect Journal Article: Strong influence of coadsorbate interaction on CO desorption dynamics on Ru(0001) probed by ultrafast x-ray spectroscopy and ab initio simulations Citation Details In-Document Search Title: Strong influence of coadsorbate interaction on CO desorption dynamics on Ru(0001) probed by ultrafast x-ray spectroscopy and ab initio simulations We show that coadsorbed oxygen

  8. Ultrafast Spectroscopy of Warm Dense Matter

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Ultrafast Spectroscopy of Warm Dense Matter Print Being neither solid, liquid, gas, nor plasma, warm dense matter (WDM) occupies a no man's land in the map of material phases. Its...

  9. Ultrafast Demagnetisation at 20 | Stanford Synchrotron Radiation

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Lightsource Ultrafast Demagnetisation at 20 Wednesday, February 10, 2016 - 3:00pm SLAC, Redtail Hawk Conference Room 108A Speaker: Christian Dornes, ETH Zurich Program Description First discovered in 1996, ultrafast demagnetisation has sparked a wide variety of research in magnetism on the femtosecond timescale. The effect observed was that the elemental ferromagnet nickel demagnetises by a considerable amount (>30%) upon excitation by an ultrashort IR laser pulse. This result was seminal

  10. Ultrafast Spectroscopy of Warm Dense Matter

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Ultrafast Spectroscopy of Warm Dense Matter Ultrafast Spectroscopy of Warm Dense Matter Print Wednesday, 25 April 2012 00:00 Being neither solid, liquid, gas, nor plasma, warm dense matter (WDM) occupies a no man's land in the map of material phases. Its temperature can range between that of planetary cores (tens of thousands K) to that of stellar cores (hundreds of thousands K). Not only is it prevalent throughout the universe, it is relevant to inertial confinement fusion (ICF) and material

  11. Computational observation of enhanced solvation of the hydroxyl radical with increased NaCl concentration

    SciTech Connect (OSTI)

    Wick, Collin D.; Dang, Liem X.

    2006-05-11

    Classical molecular dynamics simulations with many-body potentials were carried out to quantitatively determine the effect of NaCl salt concentration on the aqueous solvation and surface concentration of hydroxyl radicals. The potential of mean force technique was used to track the incremental free energy of the hydroxyl radical from the vapor, crossing the air-water interface into the aqueous bulk. Results showed increased NaCl salt concentration significantly enhanced hydroxyl radical solvation, which should significantly increase its accommodation on water droplets. This has been experimentally observed for ozone aqueous accommodation with increased NaI concentration, but to our knowledge, no experimental study has probed this for hydroxyl radicals. The origin for this effect was found to be very favorable hydroxyl radical-chloride ion interactions, being stronger than for water-chloride. This work was performed at Pacific Northwest National Laboratory (PNNL) under the auspices of the Division of Chemical Sciences, Office of Basic Energy Sciences, U.S. Department of Energy. Battelle operates PNNL for the Department of Energy.

  12. Dissecting ion-specific dielectric spectra of sodium-halide solutions into solvation water and ionic contributions

    SciTech Connect (OSTI)

    Rinne, Klaus F.; Netz, Roland R.; Gekle, Stephan

    2014-12-07

    Using extensive equilibrium molecular dynamics simulations we determine the dielectric spectra of aqueous solutions of NaF, NaCl, NaBr, and NaI. The ion-specific and concentration-dependent shifts of the static dielectric constants and the dielectric relaxation times match experimental results very well, which serves as a validation of the classical and non-polarizable ionic force fields used. The purely ionic contribution to the dielectric response is negligible, but determines the conductivity of the salt solutions. The ion-water cross correlation contribution is negative and reduces the total dielectric response by about 5%-10% for 1?M solutions. The dominating water dielectric response is decomposed into different water solvation shells and ion-pair configurations, by this the spectral blue shift and the dielectric decrement of salt solutions with increasing salt concentration is demonstrated to be primarily caused by first-solvation shell water. With rising salt concentration the simulated spectra show more pronounced deviations from a single-Debye form and can be well described by a Cole-Cole fit, in quantitative agreement with experiments. Our spectral decomposition into ionic and different water solvation shell contributions does not render the individual contributions more Debye-like, this suggests the non-Debye-like character of the dielectric spectra of salt solutions not to be due to the superposition of different elementary relaxation processes with different relaxation times. Rather, the non-Debye-like character is likely to be an inherent spectral signature of solvation water around ions.

  13. Structural Interactions within Lithium Salt Solvates: Cyclic Carbonates and Esters

    SciTech Connect (OSTI)

    Seo, D. M.; Afroz, Taliman; Allen, Joshua L.; Boyle, Paul D.; Trulove, Paul C.; De Long, Hugh C.; Henderson, Wesley A.

    2014-11-13

    Only limited information is available regarding the manner in which cyclic carbonate and ester solvents coordinate Li+ cations in electrolyte solutions for lithium batteries. One approach to gleaning significant insight into these interactions is to examine crystalline solvate structures. To this end, eight new solvate structures are reported with ethylene carbonate, ?-butyrolactone and ?-valerolactone: (EC)3:LiClO4, (EC)2:LiClO4, (EC)2:LiBF4, (GBL)4:LiPF6, (GBL)1:LiClO4, (GVL)1:LiClO4, (GBL)1:LiBF4 and (GBL)1:LiCF3SO3. The crystal structure of (EC)1:LiCF3SO3 is also re-reported for comparison. These structures enable the factors which govern the manner in which the ions are coordinated and the ion/solvent packingin the solid-stateto be scrutinized in detail.

  14. Ultrafast spin exchange-coupling torque via photo-excited charge-transfer processes

    SciTech Connect (OSTI)

    Ma, X.; Fang, F.; Li, Q.; Zhu, J.; Yang, Y.; Wu, Y. Z.; Zhao, H. B.; Lüpke, G.

    2015-10-28

    In this study, optical control of spin is of central importance in the research of ultrafast spintronic devices utilizing spin dynamics at short time scales. Recently developed optical approaches such as ultrafast demagnetization, spin-transfer and spin-orbit torques open new pathways to manipulate spin through its interaction with photon, orbit, charge or phonon. However, these processes are limited by either the long thermal recovery time or the low-temperature requirement. Here we experimentally demonstrate ultrafast coherent spin precession via optical charge-transfer processes in the exchange-coupled Fe/CoO system at room temperature. The efficiency of spin precession excitation is significantly higher and the recovery time of the exchange-coupling torque is much shorter than for the demagnetization procedure, which is desirable for fast switching. The exchange coupling is a key issue in spin valves and tunnelling junctions, and hence our findings will help promote the development of exchange-coupled device concepts for ultrafast coherent spin manipulation.

  15. Electrolyte Solvation and Ionic Association. V. Acetonitrile-Lithium Bis(fluorosulfonyl)imide (LiFSI) Mixtures

    SciTech Connect (OSTI)

    Han, Sang D.; Borodin, Oleg; Seo, D. M.; Zhou, Zhi B.; Henderson, Wesley A.

    2014-09-30

    Electrolytes with the salt lithium bis(fluorosulfonyl)imide (LiFSI) have been evaluated relative to comparable electrolytes with other lithium salts. Acetonitrile (AN) has been used as a model electrolyte solvent. The information obtained from the thermal phase behavior, solvation/ionic association interactions, quantum chemical (QC) calculations and molecular dynamics (MD) simulations (with an APPLE&P many-body polarizable force field for the LiFSI salt) of the (AN)n-LiFSI mixtures provides detailed insight into the coordination interactions of the FSI- anions and the wide variability noted in the electrolyte transport property (i.e., viscosity and ionic conductivity).

  16. A self-consistent phase-field approach to implicit solvation...

    Office of Scientific and Technical Information (OSTI)

    Publisher's Accepted Manuscript: A self-consistent phase-field approach to implicit solvation of charged molecules with Poisson-Boltzmann electrostatics This content will become...

  17. Ultrafast Transformations in Superionic Nanocrystals

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    one of the atomic species in the material will exhibit liquid-like ionic conductivity and dynamic disorder within the rigid crystalline structure of the other....

  18. Ultrafast Transformations in Superionic Nanocrystals

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    associated with a structural phase transition, one of the atomic species in the material will exhibit liquid-like ionic conductivity and dynamic disorder within the rigid...

  19. Multibody correlations in the hydrophobic solvation of glycine peptides

    SciTech Connect (OSTI)

    Harris, Robert C.; Drake, Justin A.; Pettitt, B. Montgomery

    2014-12-14

    Protein collapse during folding is often assumed to be driven by a hydrophobic solvation energy (ΔG{sub vdw}) that scales linearly with solvent-accessible surface area (A). In a previous study, we argued that ΔG{sub vdw}, as well as its attractive (ΔG{sub att}) and repulsive (ΔG{sub rep}) components, was not simply a linear function of A. We found that the surface tensions, γ{sub rep}, γ{sub att}, and γ{sub vdw}, gotten from ΔG{sub rep}, ΔG{sub att}, and ΔG{sub vdw} against A for four configurations of deca-alanine differed from those obtained for a set of alkanes. In the present study, we extend our analysis to fifty decaglycine structures and atomic decompositions. We find that different configurations of decaglycine generate different estimates of γ{sub rep}. Additionally, we considered the reconstruction of the solvation free energy from scaling the free energy of solvation of each atom type, free in solution. The free energy of the isolated atoms, scaled by the inverse surface area the atom would expose in the molecule does not reproduce the γ{sub rep} for the intact decaglycines. Finally, γ{sub att} for the decaglycine conformations is much larger in magnitude than those for deca-alanine or the alkanes, leading to large negative values of γ{sub vdw} (−74 and −56 cal/mol/Å{sup 2} for CHARMM27 and AMBER ff12sb force fields, respectively). These findings imply that ΔG{sub vdw} favors extended rather than compact structures for decaglycine. We find that ΔG{sub rep} and ΔG{sub vdw} have complicated dependencies on multibody correlations between solute atoms, on the geometry of the molecular surface, and on the chemical identities of the atoms.

  20. Ultrafast X-ray Phase-Enhanced Microimaging for Visualizing Fuel...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Ultrafast X-ray Phase-Enhanced Microimaging for Visualizing Fuel Injection Process and Diesel Sprays Ultrafast X-ray Phase-Enhanced Microimaging for Visualizing Fuel Injection ...

  1. Ultrafast spin exchange-coupling torque via photo-excited charge...

    Office of Scientific and Technical Information (OSTI)

    Ultrafast spin exchange-coupling torque via photo-excited charge-transfer processes Citation Details In-Document Search Title: Ultrafast spin exchange-coupling torque via ...

  2. Bond-valence methods for pKa prediction. II. Bond-valence, electrostatic, molecular geometry, and solvation effects

    SciTech Connect (OSTI)

    Bickmore, Barry R.; Rosso, Kevin M.; Tadanier, Christopher J.; Bylaska, Eric J.; Doud, Darrin

    2006-08-15

    In a previous contribution, we outlined a method for predicting (hydr)oxy-acid and oxide surface acidity constants based on three main factors: bond valence, Me?O bond ionicity, and molecular shape. Here electrostatics calculations and ab initio molecular dynamics simulations are used to qualitatively show that Me?O bond ionicity controls the extent to which the electrostatic work of proton removal departs from ideality, bond valence controls the extent of solvation of individual functional groups, and bond valence and molecular shape controls local dielectric response. These results are consistent with our model of acidity, but completely at odds with other methods of predicting acidity constants for use in multisite complexation models. In particular, our ab initio molecular dynamics simulations of solvated monomers clearly indicate that hydrogen bonding between (hydr)oxo-groups and water molecules adjusts to obey the valence sum rule, rather than maintaining a fixed valence based on the coordination of the oxygen atom as predicted by the standard MUSIC model.

  3. Ultrafast Optical Microscopy of Single Monolayer Molybdenum Disulfide

    Office of Scientific and Technical Information (OSTI)

    Flakes (Journal Article) | SciTech Connect Ultrafast Optical Microscopy of Single Monolayer Molybdenum Disulfide Flakes Citation Details In-Document Search Title: Ultrafast Optical Microscopy of Single Monolayer Molybdenum Disulfide Flakes We performed ultrafast optical microscopy on single flakes of atomically thin CVD-grown molybdenum disulfide, using non-degenerate femtosecond pump-probe spectroscopy to excite and probe carriers above and below the indirect and direct band gaps. These

  4. Ultrafast laser diagnostics to investigate initiation fundamentals in

    Office of Scientific and Technical Information (OSTI)

    energetic materials. (Technical Report) | SciTech Connect Technical Report: Ultrafast laser diagnostics to investigate initiation fundamentals in energetic materials. Citation Details In-Document Search Title: Ultrafast laser diagnostics to investigate initiation fundamentals in energetic materials. We present the results of a two year early career LDRD project, which has focused on the development of ultrafast diagnostics to measure temperature, pressure and chemical change during the shock

  5. Morphological changes in ultrafast laser ablation plumes with varying spot size

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Harilal, S. S.; Diwakar, P. K.; Polek, M. P.; Phillips, M. C.

    2015-06-04

    We investigated the role of spot size on plume morphology during ultrafast laser ablation of metal targets. Our results show that the spatial features of fs LA plumes are strongly dependent on the focal spot size. Two-dimensional self-emission images showed that the shape of the ultrafast laser ablation plumes changes from spherical to cylindrical with an increasing spot size from 100 to 600 ?m. The changes in plume morphology and internal structures are related to ion emission dynamics from the plasma, where broader angular ion distribution and faster ions are noticed for the smallest spot size used. The present resultsmoreclearly show that the morphological changes in the plume with spot size are independent of laser pulse width.less

  6. Ultrafast kinetics subsequent to shock compression in an oxygen...

    Office of Scientific and Technical Information (OSTI)

    to shock compression in an oxygen-balanced mixture of nitromethane and hydrogen peroxide Citation Details In-Document Search Title: Ultrafast kinetics subsequent to shock ...

  7. Ultrafast kinetics subsequent to shock in an unreacted, oxygen...

    Office of Scientific and Technical Information (OSTI)

    shock in an unreacted, oxygen balanced mixture of nitromethane and hydrogen peroxide Citation Details In-Document Search Title: Ultrafast kinetics subsequent to shock in an ...

  8. Ultrafast laser diagnostics for studies of shock initiation in...

    Office of Scientific and Technical Information (OSTI)

    for studies of shock initiation in energetic materials. Citation Details In-Document Search Title: Ultrafast laser diagnostics for studies of shock initiation in energetic ...

  9. Ultrafast Laser Diagnostics for Energetic-Material Ignition Mechanisms...

    Office of Scientific and Technical Information (OSTI)

    Technical Report: Ultrafast Laser Diagnostics for Energetic-Material Ignition Mechanisms: Tools for Physics-Based Model Development. Citation Details In-Document Search Title: ...

  10. Ultrafast Structural Rearrangements in the MLCT Excited State...

    Office of Scientific and Technical Information (OSTI)

    These results provide guidance for future x-ray structural studies on ultrafast time scale, as well as for synthesis towards its applications in solar energy conversion. less ...

  11. Ultrafast Shock Initiation of Exothermic Chemistry in Hydrogen...

    Office of Scientific and Technical Information (OSTI)

    Shock Initiation of Exothermic Chemistry in Hydrogen Peroxide Citation Details In-Document Search Title: Ultrafast Shock Initiation of Exothermic Chemistry in Hydrogen Peroxide ...

  12. Ultrafast kinetics subsequent to shock compression in an oxygen...

    Office of Scientific and Technical Information (OSTI)

    subsequent to shock compression in an oxygen-balanced mixture of nitromethane and hydrogen peroxide Citation Details In-Document Search Title: Ultrafast kinetics subsequent to...

  13. Prospects for Electron Imaging with Ultrafast Time Resolution...

    Office of Scientific and Technical Information (OSTI)

    Service, Springfield, VA at www.ntis.gov. Many pivotal aspects of material science, biomechanics, and chemistry would benefit from nanometer imaging with ultrafast time resolution....

  14. Ultra-fast framing camera tube

    DOE Patents [OSTI]

    Kalibjian, Ralph (1051 Batavia Ave., Livermore, CA 94550)

    1981-01-01

    An electronic framing camera tube features focal plane image dissection and synchronized restoration of the dissected electron line images to form two-dimensional framed images. Ultra-fast framing is performed by first streaking a two-dimensional electron image across a narrow slit, thereby dissecting the two-dimensional electron image into sequential electron line images. The dissected electron line images are then restored into a framed image by a restorer deflector operated synchronously with the dissector deflector. The number of framed images on the tube's viewing screen is equal to the number of dissecting slits in the tube. The distinguishing features of this ultra-fast framing camera tube are the focal plane dissecting slits, and the synchronously-operated restorer deflector which restores the dissected electron line images into a two-dimensional framed image. The framing camera tube can produce image frames having high spatial resolution of optical events in the sub-100 picosecond range.

  15. Ultrafast Spectroscopy of Warm Dense Matter

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Ultrafast Spectroscopy of Warm Dense Matter Print Being neither solid, liquid, gas, nor plasma, warm dense matter (WDM) occupies a no man's land in the map of material phases. Its temperature can range between that of planetary cores (tens of thousands K) to that of stellar cores (hundreds of thousands K). Not only is it prevalent throughout the universe, it is relevant to inertial confinement fusion (ICF) and material performance under extreme conditions. However, because of its extreme

  16. Ultrafast Spectroscopy of Warm Dense Matter

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Ultrafast Spectroscopy of Warm Dense Matter Print Being neither solid, liquid, gas, nor plasma, warm dense matter (WDM) occupies a no man's land in the map of material phases. Its temperature can range between that of planetary cores (tens of thousands K) to that of stellar cores (hundreds of thousands K). Not only is it prevalent throughout the universe, it is relevant to inertial confinement fusion (ICF) and material performance under extreme conditions. However, because of its extreme

  17. Ultrafast Transformations in Superionic Nanocrystals

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Transformations in Superionic Nanocrystals Print A superionic material is a multi-component solid with simultaneous characteristics of both a solid and a liquid. Above a critical temperature associated with a structural phase transition, one of the atomic species in the material will exhibit liquid-like ionic conductivity and dynamic disorder within the rigid crystalline structure of the other. Discovered by Michael Faraday almost 200 years ago, superionic materials today hold promise for use in

  18. Differential ultrafast all-optical switching of the resonances of a micropillar cavity

    SciTech Connect (OSTI)

    Thyrrestrup, Henri Yce, Emre; Ctistis, Georgios; Vos, Willem L.; Claudon, Julien; Grard, Jean-Michel

    2014-09-15

    We perform frequency- and time-resolved all-optical switching of a GaAs-AlAs micropillar cavity using an ultrafast pump-probe setup. The switching is achieved by two-photon excitation of free carriers. We track the cavity resonances in time with a high frequency resolution. The pillar modes exhibit simultaneous frequency shifts, albeit with markedly different maximum switching amplitudes and relaxation dynamics. These differences stem from the non-uniformity of the free carrier density in the micropillar, and are well understood by taking into account the spatial distribution of injected free carriers, their spatial diffusion and surface recombination at micropillar sidewalls.

  19. Solvation thermodynamics of amino acid side chains on a short peptide backbone

    SciTech Connect (OSTI)

    Hajari, Timir; Vegt, Nico F. A. van der

    2015-04-14

    The hydration process of side chain analogue molecules differs from that of the actual amino acid side chains in peptides and proteins owing to the effects of the peptide backbone on the aqueous solvent environment. A recent molecular simulation study has provided evidence that all nonpolar side chains, attached to a short peptide backbone, are considerably less hydrophobic than the free side chain analogue molecules. In contrast to this, the hydrophilicity of the polar side chains is hardly affected by the backbone. To analyze the origin of these observations, we here present a molecular simulation study on temperature dependent solvation free energies of nonpolar and polar side chains attached to a short peptide backbone. The estimated solvation entropies and enthalpies of the various amino acid side chains are compared with existing side chain analogue data. The solvation entropies and enthalpies of the polar side chains are negative, but in absolute magnitude smaller compared with the corresponding analogue data. The observed differences are large; however, owing to a nearly perfect enthalpy-entropy compensation, the solvation free energies of polar side chains remain largely unaffected by the peptide backbone. We find that a similar compensation does not apply to the nonpolar side chains; while the backbone greatly reduces the unfavorable solvation entropies, the solvation enthalpies are either more favorable or only marginally affected. This results in a very small unfavorable free energy cost, or even free energy gain, of solvating the nonpolar side chains in strong contrast to solvation of small hydrophobic or nonpolar molecules in bulk water. The solvation free energies of nonpolar side chains have been furthermore decomposed into a repulsive cavity formation contribution and an attractive dispersion free energy contribution. We find that cavity formation next to the peptide backbone is entropically favored over formation of similar sized nonpolar side chain cavities in bulk water, in agreement with earlier work in the literature on analysis of cavity fluctuations at nonpolar molecular surfaces. The cavity and dispersion interaction contributions correlate quite well with the solvent accessible surface area of the nonpolar side chains attached to the backbone. This correlation however is weak for the overall solvation free energies owing to the fact that the cavity and dispersion free energy contributions are almost exactly cancelling each other.

  20. Ultrafast transient reflectance of epitaxial semiconducting perovskite thin films

    SciTech Connect (OSTI)

    Smolin, S. Y.; Guglietta, G. W.; Baxter, J. B. E-mail: smay@coe.drexel.edu; Scafetta, M. D.; May, S. J. E-mail: smay@coe.drexel.edu

    2014-07-14

    Ultrafast pump-probe transient reflectance (TR) spectroscopy was used to study carrier dynamics in an epitaxial perovskite oxide thin film of LaFeO{sub 3} (LFO) with a thickness of 40 unit cells (16?nm) grown by molecular beam epitaxy on (LaAlO{sub 3}){sub 0.3}(Sr{sub 2}AlTaO{sub 6}){sub 0.7} (LSAT). TR spectroscopy shows two negative transients in reflectance with local maxima at ?2.5?eV and ?3.5?eV which correspond to two optical transitions in LFO as determined by ellipsometry. The kinetics at these transients were best fit with an exponential decay model with fast (540 ps), medium (?200 ps), and slow (??3?ns) components that we attribute mainly to recombination of photoexcited carriers. Moreover, these reflectance transients did not completely decay within the observable time window, indicating that ?10% of photoexcited carriers exist for at least 3?ns. This work illustrates that TR spectroscopy can be performed on thin (<20?nm) epitaxial oxide films to provide a quantitative understanding of recombination lifetimes, which are important parameters for the potential utilization of perovskite films in photovoltaic and photocatalytic applications.

  1. Apparatus and method for characterizing ultrafast polarization varying optical pulses

    DOE Patents [OSTI]

    Smirl, Arthur (1020 Cherry La. Northwest, Iowa City, IA 52240); Trebino, Rick P. (425 Mulqueeny St., Livermore, CA 94550)

    1999-08-10

    Practical techniques are described for characterizing ultrafast potentially ultraweak, ultrashort optical pulses. The techniques are particularly suited to the measurement of signals from nonlinear optical materials characterization experiments, whose signals are generally too weak for full characterization using conventional techniques.

  2. New Algorithm Enables Faster Simulations of Ultrafast Processes

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Ultrafast Processes Opens the Door for Real-Time Simulations in Atomic-Level Materials ... Numerical simulations in real time provide the best way to study these processes, but such ...

  3. Calculation of the Gibbs Free Energy of Solvation and Dissociation of HCl in Water via Monte Carlo Simulations and Continuum Solvation Models

    SciTech Connect (OSTI)

    McGrath, Matthew; Kuo, I-F W.; Ngouana, Brice F.; Ghogomu, Julius N.; Mundy, Christopher J.; Marenich, Aleksandr; Cramer, Christopher J.; Truhlar, Donald G.; Siepmann, Joern I.

    2013-08-28

    The free energy of solvation and dissociation of hydrogen chloride in water is calculated through a combined molecular simulation quantum chemical approach at four temperatures between T = 300 and 450 K. The free energy is first decomposed into the sum of two components: the Gibbs free energy of transfer of molecular HCl from the vapor to the aqueous liquid phase and the standard-state free energy of acid dissociation of HCl in aqueous solution. The former quantity is calculated using Gibbs ensemble Monte Carlo simulations using either Kohn-Sham density functional theory or a molecular mechanics force field to determine the system’s potential energy. The latter free energy contribution is computed using a continuum solvation model utilizing either experimental reference data or micro-solvated clusters. The predicted combined solvation and dissociation free energies agree very well with available experimental data. CJM was supported by the US Department of Energy,Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences & Biosciences. Pacific Northwest National Laboratory is operated by Battelle for the US Department of Energy.

  4. New Algorithm Enables Faster Simulations of Ultrafast Processes

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Algorithm Enables Faster Simulations of Ultrafast Processes New Algorithm Enables Faster Simulations of Ultrafast Processes Opens the Door for Real-Time Simulations in Atomic-Level Materials Research February 20, 2015 Contact: Rachel Berkowitz, 510-486-7254, rberkowitz@lbl.gov femtosecondalgorithm copy Model of ion (Cl) collision with atomically thin semiconductor (MoSe2). Collision region is shown in blue and zoomed in; red points show initial positions of Cl. The simulation calculates the

  5. Plasmas, Dielectrics and the Ultrafast: First Science and Operational

    Office of Scientific and Technical Information (OSTI)

    Experience at FACET (Conference) | SciTech Connect Conference: Plasmas, Dielectrics and the Ultrafast: First Science and Operational Experience at FACET Citation Details In-Document Search Title: Plasmas, Dielectrics and the Ultrafast: First Science and Operational Experience at FACET FACET (Facility for Advanced Accelerator and Experimental Tests) is an accelerator R&D test facility that has been recently constructed at SLAC National Accelerator Laboratory. The facility provides 20 GeV,

  6. Plasmas, Dielectrics and the Ultrafast: First Science and Operational

    Office of Scientific and Technical Information (OSTI)

    Experience at FACET (Conference) | SciTech Connect Conference: Plasmas, Dielectrics and the Ultrafast: First Science and Operational Experience at FACET Citation Details In-Document Search Title: Plasmas, Dielectrics and the Ultrafast: First Science and Operational Experience at FACET FACET (Facility for Advanced Accelerator and Experimental Tests) is an accelerator R&D test facility that has been recently constructed at SLAC National Accelerator Laboratory. The facility provides 20 GeV,

  7. Ultrafast Laser Diagnostics for Energetic-Material Ignition Mechanisms:

    Office of Scientific and Technical Information (OSTI)

    Tools for Physics-Based Model Development. (Technical Report) | SciTech Connect Ultrafast Laser Diagnostics for Energetic-Material Ignition Mechanisms: Tools for Physics-Based Model Development. Citation Details In-Document Search Title: Ultrafast Laser Diagnostics for Energetic-Material Ignition Mechanisms: Tools for Physics-Based Model Development. We present the results of an LDRD project to develop diagnostics to perform fundamental measurements of material properties during shock

  8. Electronic Coupling Dependence of Ultrafast Interfacial Electron Transfer

    Office of Scientific and Technical Information (OSTI)

    on Nanocrystalline Thin Films and Single Crystal (Technical Report) | SciTech Connect Electronic Coupling Dependence of Ultrafast Interfacial Electron Transfer on Nanocrystalline Thin Films and Single Crystal Citation Details In-Document Search Title: Electronic Coupling Dependence of Ultrafast Interfacial Electron Transfer on Nanocrystalline Thin Films and Single Crystal × You are accessing a document from the Department of Energy's (DOE) SciTech Connect. This site is a product of DOE's

  9. Ultrafast Laser Diagnostics for Energetic-Material Ignition Mechanisms:

    Office of Scientific and Technical Information (OSTI)

    Tools for Physics-Based Model Development. (Technical Report) | SciTech Connect Technical Report: Ultrafast Laser Diagnostics for Energetic-Material Ignition Mechanisms: Tools for Physics-Based Model Development. Citation Details In-Document Search Title: Ultrafast Laser Diagnostics for Energetic-Material Ignition Mechanisms: Tools for Physics-Based Model Development. × You are accessing a document from the Department of Energy's (DOE) SciTech Connect. This site is a product of DOE's Office

  10. Ultrafast Laser Diagnostics for Energetic-Material Ignition Mechanisms:

    Office of Scientific and Technical Information (OSTI)

    Tools for Physics-Based Model Development. (Technical Report) | SciTech Connect Technical Report: Ultrafast Laser Diagnostics for Energetic-Material Ignition Mechanisms: Tools for Physics-Based Model Development. Citation Details In-Document Search Title: Ultrafast Laser Diagnostics for Energetic-Material Ignition Mechanisms: Tools for Physics-Based Model Development. We present the results of an LDRD project to develop diagnostics to perform fundamental measurements of material properties

  11. Ultrafast Laser Diagnostics for Studies of Shock Initiation in Energetic

    Office of Scientific and Technical Information (OSTI)

    Materials. (Conference) | SciTech Connect Ultrafast Laser Diagnostics for Studies of Shock Initiation in Energetic Materials. Citation Details In-Document Search Title: Ultrafast Laser Diagnostics for Studies of Shock Initiation in Energetic Materials. Abstract not provided. Authors: Farrow, Darcie ; Kearney, Sean Patrick ; Jilek, Brook Anton ; Urayama, Junji ; Kohl, Ian Thomas Publication Date: 2013-06-01 OSTI Identifier: 1115245 Report Number(s): SAND2013-5254C 478660 DOE Contract Number:

  12. Ultrafast Laser Diagnostics to Investigate Initiation Fundamentals in

    Office of Scientific and Technical Information (OSTI)

    Energetic Materials. (Conference) | SciTech Connect Conference: Ultrafast Laser Diagnostics to Investigate Initiation Fundamentals in Energetic Materials. Citation Details In-Document Search Title: Ultrafast Laser Diagnostics to Investigate Initiation Fundamentals in Energetic Materials. Abstract not provided. Authors: Farrow, Darcie ; Kearney, Sean Patrick ; Scoglietti, Daniel Publication Date: 2011-08-01 OSTI Identifier: 1143441 Report Number(s): SAND2011-5736C 481988 DOE Contract Number:

  13. Ultrafast Laser Fabrication: a Rapid Prototyping Capability for CINT

    Office of Scientific and Technical Information (OSTI)

    (Technical Report) | SciTech Connect Technical Report: Ultrafast Laser Fabrication: a Rapid Prototyping Capability for CINT Citation Details In-Document Search Title: Ultrafast Laser Fabrication: a Rapid Prototyping Capability for CINT Authors: McCulloch, Quinn [1] ; Dattelbaum, Andrew M. [1] ; Nath, Pulak [1] + Show Author Affiliations Los Alamos National Laboratory Publication Date: 2013-03-04 OSTI Identifier: 1067392 Report Number(s): LA-UR-13-21541 DOE Contract Number: AC52-06NA25396

  14. Ultrafast Optical Microscopy of Single Monolayer Molybdenum Disulfide

    Office of Scientific and Technical Information (OSTI)

    Flakes (Journal Article) | SciTech Connect Journal Article: Ultrafast Optical Microscopy of Single Monolayer Molybdenum Disulfide Flakes Citation Details In-Document Search Title: Ultrafast Optical Microscopy of Single Monolayer Molybdenum Disulfide Flakes × You are accessing a document from the Department of Energy's (DOE) SciTech Connect. This site is a product of DOE's Office of Scientific and Technical Information (OSTI) and is provided as a public service. Visit OSTI to utilize

  15. Ultrafast all-optical manipulation of interfacial magnetoelectric coupling

    Office of Scientific and Technical Information (OSTI)

    (Technical Report) | SciTech Connect SciTech Connect Search Results Technical Report: Ultrafast all-optical manipulation of interfacial magnetoelectric coupling Citation Details In-Document Search Title: Ultrafast all-optical manipulation of interfacial magnetoelectric coupling Authors: Sheu, Yu-Miin [1] + Show Author Affiliations Los Alamos National Laboratory [Los Alamos National Laboratory Publication Date: 2014-04-24 OSTI Identifier: 1129830 Report Number(s): LA-UR-14-22829 DOE Contract

  16. Ultrafast observation of shocked states in a precompressed material

    Office of Scientific and Technical Information (OSTI)

    (Journal Article) | SciTech Connect Ultrafast observation of shocked states in a precompressed material Citation Details In-Document Search Title: Ultrafast observation of shocked states in a precompressed material Authors: Armstrong, M R ; Crowhurst, J C ; Bastea, S ; Zaug, J M Publication Date: 2010-07-08 OSTI Identifier: 1117984 Report Number(s): LLNL-JRNL-442472 DOE Contract Number: W-7405-ENG-48 Resource Type: Journal Article Resource Relation: Journal Name: Journal of Applied Physics,

  17. An ultrafast silicon nanoplasmonic ballistic triode

    SciTech Connect (OSTI)

    Greig, S. R. Elezzabi, A. Y.

    2014-12-15

    A nanoscale three terminal silicon based nanoplasmonic triode is proposed as a nanometer transistor. The device is suitable for monolithic integration with complementary-metal-oxide-semiconductor technology. Due to the highly spatially inhomogeneous, highly confined nanoplasmonic mode, electrons generated through two-photon absorption in the silicon are ponderomotively accelerated towards the copper anode producing an output current. Application of a negative grid voltage allows for control of the output current. The nanoplasmonic triode is able to achieve output current as high as 628?mA/?m on an ultrafast timescale of 150 fs in a compact footprint of 0.07??m{sup 2}. Reduction of the plasmonic field strength allows for a CMOS compatible current of 11.7?mA/?m. The results demonstrate the potential for the compact optical control of current useful for applications in high-speed, high current switching, and amplification.

  18. Anion Coordination Interactions in Solvates with the Lithium Salts LiDCTA and LiTDI

    SciTech Connect (OSTI)

    McOwen, Dennis W.; Delp, Samuel A.; Paillard, Elie; Herriot, Cristelle; Han, Sang D.; Boyle, Paul D.; Sommer, Roger D.; Henderson, Wesley A.

    2014-04-17

    Lithium 4,5-dicyano-1,2,3-triazolate (LiDCTA) and lithium 2-trifluoromethyl-4,5-dicyanoimidazole (LiTDI) are two salts proposed for lithium battery electrolyte applications, but little is known about the manner in which the DCTA- and TDI- anions coordinate Li+ cations. To explore this in-depth, crystal structures are reported here for two solvates with LiDCTA: (G2)1:LiDCTA and (G1)1:LiDCTA with diglyme and monoglyme, respectively, and seven solvates with LiTDI: (G1)2:LiTDI, (G2)2:LiTDI, (G3)1:LiTDI, (THF)1:LiTDI, (EC)1:LiTDI, (PC)1:LiTDI and (DMC)1/2:LiTDI with monoglyme, diglyme, triglyme, tetrahydrofuran, ethylene carbonate, propylene carbonate and dimethyl carbonate, respectively. These latter solvate structures are compared with the previously reported acetonitrile (AN)2:LiTDI structure. The solvates indicate that the LiTDI salt is much less associated than the LiDCTA salt and that the ions in LiTDI, when aggregated in solvates, have a very similar TDI-...Li+ cation mode of coordination through both the anion ring and cyano nitrogen atoms. Such coordination facilitates the formation of polymeric ion aggregates, instead of dimers. Insight into such ion speciation is instrumental for understanding the electrolyte properties of aprotic solvent mixtures with these salts.

  19. Solvation of molecules in superfluid helium enhances the interaction induced localization effect

    SciTech Connect (OSTI)

    Walewski, ?ukasz Forbert, Harald; Marx, Dominik

    2014-04-14

    Atomic nuclei become delocalized at low temperatures as a result of quantum effects, whereas they are point-like in the high temperature (classical) limit. For non-interacting nuclei, the delocalization upon lowering the temperature is quantitatively described in terms of the thermal de Broglie wavelength of free particles. Clearly, light non-interacting nuclei the proton being a prominent one are much more delocalized at low temperatures compared to heavy nuclei, such as non-interacting oxygen having water in mind. However, strong interactions due to chemical bonding in conjunction with ultra-low temperatures characteristic to superfluid helium nanodroplets change this common picture substantially for nuclei in molecules or clusters. It turns out that protons shared in hydrogen bonds undergo an extreme interaction induced localization at temperatures on the order of 1 K, which compresses the protonic spatial distributions to the size of the much heavier donor or acceptor atoms, such as O or Cl nuclei, corresponding to about 0.1% of the volume occupied by a non-interacting proton at the same temperature. Moreover, applying our recently developed hybrid ab initio path integral molecular dynamics/bosonic path integral Monte Carlo quantum simulation technique to a HCl/water cluster, HCl(H{sub 2}O){sub 4}, we find that helium solvation has a significant additional localizing effect of up to about 30% in volume. In particular, the solvent-induced excess localization is the stronger the lesser the given nucleus is already localized in the gas phase reference situation.

  20. Ultrafast myoglobin structural dynamics observed with an X-ray...

    Office of Scientific and Technical Information (OSTI)

    to propagate through the protein as a quake-like intramolecular motion. Here we report direct experimental evidence of such 'proteinquake' observed in myoglobin through...

  1. Ultrafast Core-Hole Induced Dynamics in Water

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Swedish Research Council, Swedish National Supercomputer Center, Center for Parallel Computers (Sweden), German Federal Ministry of Education and Research. Operation of the...

  2. Ultrafast Core-Hole Induced Dynamics in Water

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    aqueous systems is essential for many diverse fields, from condensed matter physics to medicine to environmental science. An incoming photon with enough energy to produce a core...

  3. In the OSTI Collections: Ultrafast Processes | OSTI, US Dept of Energy,

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Office of Scientific and Technical Information Ultrafast Processes Article Acknowledgement: Dr. William N. Watson, Physicist DOE Office of Scientific and Technical Information Examples of ultrafast chemical and electronic processes Further examples of electronic processes Chemical reactions from shock waves Ultrafast instruments References Research Organizations Reports available through OSTI's SciTech Connect Patent available through OSTI's DOepatents Additional References Because the atoms

  4. Pulse radiolysis studies of solvated electrons in supercritical ethane with methanol as cosolvent.

    SciTech Connect (OSTI)

    Dimitrijevic, N. M.; Takahashi, K.; Bartels, D. M.; Jonah, C. D.; Chemistry

    2001-08-02

    Pulse radiolysis has been used to study the solvated electron in supercritical ethane with methanol as a cosolvent. These measurements give information about the liquid structure of the cosolvent in these systems. The results show that at temperatures below 110 {sup o}C, there are high local concentrations of alcohol molecules (clusters), which are capable of solvating an electron. The agglomeration number of methanol clusters depends on mole fraction of alcohol at a fixed temperature. Addition of salts increases the size of methanol clusters.

  5. reactive ion solvation and solid-liquid interfacial reactions in aqueous

    Office of Scientific and Technical Information (OSTI)

    and non-aqueous media. (Conference) | SciTech Connect reactive ion solvation and solid-liquid interfacial reactions in aqueous and non-aqueous media. Citation Details In-Document Search Title: reactive ion solvation and solid-liquid interfacial reactions in aqueous and non-aqueous media. Abstract not provided. Authors: Leung, Kevin Publication Date: 2012-07-01 OSTI Identifier: 1116815 Report Number(s): SAND2012-5477C 480644 DOE Contract Number: AC04-94AL85000 Resource Type: Conference

  6. Ultrafast terahertz gating of the polarization and giant nonlinear optical

    Office of Scientific and Technical Information (OSTI)

    response in BiFeO3 thin films (Journal Article) | SciTech Connect Journal Article: Ultrafast terahertz gating of the polarization and giant nonlinear optical response in BiFeO3 thin films Citation Details In-Document Search Title: Ultrafast terahertz gating of the polarization and giant nonlinear optical response in BiFeO3 thin films In this article, terahertz pulses are applied as an all-optical bias to ferroelectric thin-film BiFeO3 while monitoring the time-dependent ferroelectric

  7. Ultrafast spin tunneling and injection in coupled nanostructures of InGaAs quantum dots and quantum well

    SciTech Connect (OSTI)

    Yang, Xiao-Jie Kiba, Takayuki; Yamamura, Takafumi; Takayama, Junichi; Subagyo, Agus; Sueoka, Kazuhisa; Murayama, Akihiro

    2014-01-06

    We investigate the electron-spin injection dynamics via tunneling from an In{sub 0.1}Ga{sub 0.9}As quantum well (QW) to In{sub 0.5}Ga{sub 0.5}As quantum dots (QDs) in coupled QW-QDs nanostructures. These coupled nanostructures demonstrate ultrafast (5 to 20 ps) spin injection into the QDs. The degree of spin polarization up to 45% is obtained in the QDs after the injection, essentially depending on the injection time. The spin injection and conservation are enhanced with thinner barriers due to the stronger electronic coupling between the QW and QDs.

  8. Apparatus and method for characterizing ultrafast polarization varying optical pulses

    DOE Patents [OSTI]

    Smirl, A.; Trebino, R.P.

    1999-08-10

    Practical techniques are described for characterizing ultrafast potentially ultraweak, ultrashort optical pulses. The techniques are particularly suited to the measurement of signals from nonlinear optical materials characterization experiments, whose signals are generally too weak for full characterization using conventional techniques. 2 figs.

  9. Ultra-Fast Chemical Conversion Surfaces | Department of Energy

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    1 DOE Hydrogen and Fuel Cells Program, and Vehicle Technologies Program Annual Merit Review and Peer Evaluation PDF icon pm027_erdemir_2011_p.pdf More Documents & Publications Ultra-Fast Chemical Conversion Surfaces Lubricant-Friendly, Superhard and Low-Friction Coatings by Design Low-Friction Hard Coatings

  10. Dynamic

    Office of Legacy Management (LM)

    Dynamic , and Static , Res.ponse of the Government Oil Shale Mine at ' , . , Rifle, Colorado, to the Rulison Event. , . ; . . DISCLAIMER Portions of this document may be illegible in electronic image products. Images are produced from the best available original document. p ( y c - - a 2-1 0 -4- REPORT AT (29-2) 914 USBM 1 0 0 1 UNITED STATES DEPARTMENT O F THE I NTERIOR BUREAU OF MINES e s.09 P. L. R U S S E L L RESEARCH D l RECTOR Februory 2, lB7O DYNAMIC AND STATIC RESPONSE 'OF THE GOVERNMENT

  11. Quasiparticle dynamics across the full Brillouin zone of Bi2Sr2CaCu2O8+δ

    Office of Scientific and Technical Information (OSTI)

    traced with ultrafast time and angle-resolved photoemission spectroscopy (Journal Article) | SciTech Connect Quasiparticle dynamics across the full Brillouin zone of Bi2Sr2CaCu2O8+δ traced with ultrafast time and angle-resolved photoemission spectroscopy Citation Details In-Document Search Title: Quasiparticle dynamics across the full Brillouin zone of Bi2Sr2CaCu2O8+δ traced with ultrafast time and angle-resolved photoemission spectroscopy A hallmark in the cuprate family of

  12. Ultrafast Control of Magnetism in Ferromagnetic Semiconductors via Photoexcited Transient Carriers

    SciTech Connect (OSTI)

    Cotoros, Ingrid A.

    2008-12-12

    The field of spintronics offers perspectives for seamless integration of coupled and inter-tunable electrical and magnetic properties in a single device. For integration of the spin degree of freedom with current electronic technology, new semiconductors are needed that show electrically-tunable magnetic properties at room temperature and above. Dilute magnetic semiconductors derived from III-V compounds, like GaMnAs and InMnAs, show coupled and tunable magnetic, transport, and optical properties, due to the fact that their ferromagnetism is hole-mediated. These unconventional materials are ideal systems for manipulating the magnetic order by changing the carrier polarization, population density, and energy band distribution of the complementary subsystem of holes. This is the main theme we cover in this thesis. In particular, we develop a unique setup by use of ultraviolet pump, near-infrared probe femtosecond laser pulses, that allows for magneto-optical Kerr effect (MOKE) spectroscopy experiments. We photo-excite transient carriers in our samples, and measure the induced transient magnetization dynamics. One set of experiments performed allowed us to observe for the first time enhancement of the ferromagnetic order in GaMnAs, on an ultrafast time scale of hundreds of picoseconds. The corresponding transient increase of Curie temperature (Tc, the temperature above which a ferromagnetic material loses its permanent magnetism) of about 1 K for our experimental conditions is a very promising result for potential spintronics applications, especially since it is seconded by observation of an ultrafast ferromagnetic to paramagnetic phase transition above Tc. In a different set of experiments, we"write" the magnetization in a particular orientation in the sample plane. Using an ultrafast scheme, we alter the distribution of holes in the system and detect signatures of the particular memory state in the subsequent magnetization dynamics, with unprecedented hundreds of femtosecond detection speed. The femtosecond cooperative magnetic phenomena presented here further our understanding of Mn-hole correlations in III-V dilute magnetic semiconductors, and may well represent universal principles of a large class of carrier-mediated ferromagnetic materials. Thus they offer perspectives for future terahertz (1012 Hz) speed"spintronic" functional devices.

  13. The ALS X-Ray Streak Camera: Bringing the Ultrafast and Ultrasmall into

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Focus The ALS X-Ray Streak Camera: Bringing the Ultrafast and Ultrasmall into Focus Print Studying the world of the ultrasmall and the ultrafast is at the frontier of scientific research. Two x-ray approaches can be used for ultrafast examinations. The first entails developing sources that have short x-ray pulses such as free-electron lasers and slicing sources, which will provide the ultrafast temporal information. The other approach is to develop a detector that is fast enough to resolve

  14. The ALS X-Ray Streak Camera: Bringing the Ultrafast and Ultrasmall into

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Focus The ALS X-Ray Streak Camera: Bringing the Ultrafast and Ultrasmall into Focus Print Studying the world of the ultrasmall and the ultrafast is at the frontier of scientific research. Two x-ray approaches can be used for ultrafast examinations. The first entails developing sources that have short x-ray pulses such as free-electron lasers and slicing sources, which will provide the ultrafast temporal information. The other approach is to develop a detector that is fast enough to resolve

  15. The ALS X-Ray Streak Camera: Bringing the Ultrafast and Ultrasmall into

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Focus The ALS X-Ray Streak Camera: Bringing the Ultrafast and Ultrasmall into Focus Print Studying the world of the ultrasmall and the ultrafast is at the frontier of scientific research. Two x-ray approaches can be used for ultrafast examinations. The first entails developing sources that have short x-ray pulses such as free-electron lasers and slicing sources, which will provide the ultrafast temporal information. The other approach is to develop a detector that is fast enough to resolve

  16. The ALS X-Ray Streak Camera: Bringing the Ultrafast and Ultrasmall into

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Focus The ALS X-Ray Streak Camera: Bringing the Ultrafast and Ultrasmall into Focus Print Studying the world of the ultrasmall and the ultrafast is at the frontier of scientific research. Two x-ray approaches can be used for ultrafast examinations. The first entails developing sources that have short x-ray pulses such as free-electron lasers and slicing sources, which will provide the ultrafast temporal information. The other approach is to develop a detector that is fast enough to resolve

  17. The ALS X-Ray Streak Camera: Bringing the Ultrafast and Ultrasmall into

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Focus The ALS X-Ray Streak Camera: Bringing the Ultrafast and Ultrasmall into Focus Print Studying the world of the ultrasmall and the ultrafast is at the frontier of scientific research. Two x-ray approaches can be used for ultrafast examinations. The first entails developing sources that have short x-ray pulses such as free-electron lasers and slicing sources, which will provide the ultrafast temporal information. The other approach is to develop a detector that is fast enough to resolve

  18. The ALS X-Ray Streak Camera: Bringing the Ultrafast and Ultrasmall into

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Focus The ALS X-Ray Streak Camera: Bringing the Ultrafast and Ultrasmall into Focus The ALS X-Ray Streak Camera: Bringing the Ultrafast and Ultrasmall into Focus Print Wednesday, 26 March 2008 00:00 Studying the world of the ultrasmall and the ultrafast is at the frontier of scientific research. Two x-ray approaches can be used for ultrafast examinations. The first entails developing sources that have short x-ray pulses such as free-electron lasers and slicing sources, which will provide the

  19. Ultrafast electron transport across nano gaps in nanowire circuits

    SciTech Connect (OSTI)

    Potma, Eric O.

    2015-07-31

    In this Program we aim for a closer look at electron transfer through single molecules. To achieve this, we use ultrafast laser pulses to time stamp an electron tunneling event in a molecule that is connected between two metallic electrodes, while reading out the electron current. A key aspect of this project is the use of metallic substrates with plasmonic activity to efficiently manipulate the tunneling probability. The first Phase of this program is concerned with developing highly sensitive tools for the ultrafast optical manipulation of tethered molecules through the evanescent surface field of plasmonic substrates. The second Phase of the program aims to use these tools for exercising control over the electron tunneling probability.

  20. New 'Molecular Movie' Reveals Ultrafast Chemistry in Motion

    SciTech Connect (OSTI)

    Minitti, Michael

    2015-06-22

    Scientists for the first time tracked ultrafast structural changes, captured in quadrillionths-of-a-second steps, as ring-shaped gas molecules burst open and unraveled. Ring-shaped molecules are abundant in biochemistry and also form the basis for many drug compounds. The study points the way to a wide range of real-time X-ray studies of gas-based chemical reactions that are vital to biological processes.

  1. Ultrafast kinetics subsequent to shock in an unreacted, oxygen balanced

    Office of Scientific and Technical Information (OSTI)

    mixture of nitromethane and hydrogen peroxide (Conference) | SciTech Connect kinetics subsequent to shock in an unreacted, oxygen balanced mixture of nitromethane and hydrogen peroxide Citation Details In-Document Search Title: Ultrafast kinetics subsequent to shock in an unreacted, oxygen balanced mixture of nitromethane and hydrogen peroxide Authors: Armstrong, M R ; Zaug, J M ; Grant, C D ; Crowhurst, J C ; Bastea, S Publication Date: 2014-06-24 OSTI Identifier: 1149544 Report Number(s):

  2. Ultrafast kinetics subsequent to shock in an unreacted, oxygen balanced

    Office of Scientific and Technical Information (OSTI)

    mixture of nitromethane and hydrogen peroxide (Conference) | SciTech Connect kinetics subsequent to shock in an unreacted, oxygen balanced mixture of nitromethane and hydrogen peroxide Citation Details In-Document Search Title: Ultrafast kinetics subsequent to shock in an unreacted, oxygen balanced mixture of nitromethane and hydrogen peroxide × You are accessing a document from the Department of Energy's (DOE) SciTech Connect. This site is a product of DOE's Office of Scientific and

  3. Observing Interactions as they happen: Ultrafast Optical Spectroscopies of

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Quantum Materials | Stanford Synchrotron Radiation Lightsource Observing Interactions as they happen: Ultrafast Optical Spectroscopies of Quantum Materials Wednesday, January 13, 2016 - 3:00pm SLAC, Redtail Hawk Conference Room 108A Speaker: Giacomo Coslovich, LCLS Program Description Quantum materials exhibit strong and competing interactions between their fundamental constituents, leading to exotic properties such as high-temperature superconductivity and nanoscale charge and spin

  4. Ultra-Fast Chemical Conversion Surfaces | Department of Energy

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    0 DOE Vehicle Technologies and Hydrogen Programs Annual Merit Review and Peer Evaluation Meeting, June 7-11, 2010 -- Washington D.C. PDF icon pm027_erdemir_2010_p.pdf More Documents & Publications Ultra-Fast Chemical Conversion Surfaces Lubricant-Friendly, Superhard and Low-Friction Coatings by Design ITP Energy Intensive Processes: Energy-Intensive Processes Portfolio: Addressing Key Energy Challenges Across U.S. Industry

  5. Ultrafast Laser Diagnostics to Investigate Initiation in Energetic

    Office of Scientific and Technical Information (OSTI)

    Materials. (Conference) | SciTech Connect Laser Diagnostics to Investigate Initiation in Energetic Materials. Citation Details In-Document Search Title: Ultrafast Laser Diagnostics to Investigate Initiation in Energetic Materials. Abstract not provided. Authors: Farrow, Darcie Publication Date: 2012-01-01 OSTI Identifier: 1118319 Report Number(s): SAND2012-0257C 481469 DOE Contract Number: AC04-94AL85000 Resource Type: Conference Resource Relation: Conference: NW external LDRD review held

  6. Ultrafast Terahertz Probes of Interacting Dark Excitons in

    Office of Scientific and Technical Information (OSTI)

    Chirality-Specific Semiconducting Single-Walled Carbon Nanotubes (Journal Article) | SciTech Connect Terahertz Probes of Interacting Dark Excitons in Chirality-Specific Semiconducting Single-Walled Carbon Nanotubes Citation Details In-Document Search Title: Ultrafast Terahertz Probes of Interacting Dark Excitons in Chirality-Specific Semiconducting Single-Walled Carbon Nanotubes Authors: Luo, Liang ; Chatzakis, Ioannis ; Patz, Aaron ; Wang, Jigang Publication Date: 2015-03-13 OSTI

  7. Ultrafast kinetics subsequent to shock in an unreacted, oxygen balanced

    Office of Scientific and Technical Information (OSTI)

    mixture of nitromethane and hydrogen peroxide (Conference) | SciTech Connect kinetics subsequent to shock in an unreacted, oxygen balanced mixture of nitromethane and hydrogen peroxide Citation Details In-Document Search Title: Ultrafast kinetics subsequent to shock in an unreacted, oxygen balanced mixture of nitromethane and hydrogen peroxide Authors: Armstrong, M R ; Zaug, J M ; Grant, C D ; Crowhurst, J C ; Bastea, S Publication Date: 2014-06-24 OSTI Identifier: 1149544 Report Number(s):

  8. Ultrafast laser diagnostics for studies of shock initiation in energetic

    Office of Scientific and Technical Information (OSTI)

    materials. (Conference) | SciTech Connect laser diagnostics for studies of shock initiation in energetic materials. Citation Details In-Document Search Title: Ultrafast laser diagnostics for studies of shock initiation in energetic materials. Abstract not provided. Authors: Farrow, Darcie ; Kearney, Sean Patrick ; Urayama, Junji ; Jilek, Brook Anton ; Kohl, Ian Thomas Publication Date: 2013-02-01 OSTI Identifier: 1116107 Report Number(s): SAND2013-1409C 480122 DOE Contract Number:

  9. Surface Protonation at the Rutile (110) Interface: Explicit Incorporation of Solvation Structure within the Refined MUSIC Model Framework

    SciTech Connect (OSTI)

    Machesky, Michael L.; Predota, M.; Wesolowski, David J

    2008-11-01

    The detailed solvation structure at the (110) surface of rutile ({alpha}-TiO{sub 2}) in contact with bulk liquid water has been obtained primarily from experimentally verified classical molecular dynamics (CMD) simulations of the ab initio-optimized surface in contact with SPC/E water. The results are used to explicitly quantify H-bonding interactions, which are then used within the refined MUSIC model framework to predict surface oxygen protonation constants. Quantum mechanical molecular dynamics (QMD) simulations in the presence of freely dissociable water molecules produced H-bond distributions around deprotonated surface oxygens very similar to those obtained by CMD with nondissociable SPC/E water, thereby confirming that the less computationally intensive CMD simulations provide accurate H-bond information. Utilizing this H-bond information within the refined MUSIC model, along with manually adjusted Ti-O surface bond lengths that are nonetheless within 0.05 {angstrom} of those obtained from static density functional theory (DFT) calculations and measured in X-ray reflectivity experiments (as well as bulk crystal values), give surface protonation constants that result in a calculated zero net proton charge pH value (pHznpc) at 25 C that agrees quantitatively with the experimentally determined value (5.4 {+-} 0.2) for a specific rutile powder dominated by the (110) crystal face. Moreover, the predicted pH{sub znpc} values agree to within 0.1 pH unit with those measured at all temperatures between 10 and 250 C. A slightly smaller manual adjustment of the DFT-derived Ti-O surface bond lengths was sufficient to bring the predicted pH{sub znpc} value of the rutile (110) surface at 25 C into quantitative agreement with the experimental value (4.8 {+-} 0.3) obtained from a polished and annealed rutile (110) single crystal surface in contact with dilute sodium nitrate solutions using second harmonic generation (SHG) intensity measurements as a function of ionic strength. Additionally, the H-bond interactions between protolyzable surface oxygen groups and water were found to be stronger than those between bulk water molecules at all temperatures investigated in our CMD simulations (25, 150 and 250 C). Comparison with the protonation scheme previously determined for the (110) surface of isostructural cassiterite ({alpha}-SnO{sub 2}) reveals that the greater extent of H-bonding on the latter surface, and in particular between water and the terminal hydroxyl group (Sn-OH) results in the predicted protonation constant for that group being lower than for the bridged oxygen (Sn-O-Sn), while the reverse is true for the rutile (110) surface. These results demonstrate the importance of H-bond structure in dictating surface protonation behavior, and that explicit use of this solvation structure within the refined MUSIC model framework results in predicted surface protonation constants that are also consistent with a variety of other experimental and computational data.

  10. Ultrafast Chemistry under Nonequilibrium Conditions and the Shock to Deflagration Transition at the Nanoscale

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Wood, Mitchell A.; Cherukara, Mathew J.; Kober, Edward M.; Strachan, Alejandro

    2015-06-13

    We use molecular dynamics simulations to describe the chemical reactions following shock-induced collapse of cylindrical pores in the high-energy density material RDX. For shocks with particle velocities of 2 km/s we find that the collapse of a 40 nm diameter pore leads to a deflagration wave. Molecular collisions during the collapse lead to ultrafast, multistep chemical reactions that occur under nonequilibrium conditions. WE found that exothermic products formed during these first few picoseconds prevent the nanoscale hotspot from quenching. Within 30 ps, a local deflagration wave develops. It propagates at 0.25 km/s and consists of an ultrathin reaction zone ofmore » only ~5 nm, thus involving large temperature and composition gradients. Contrary to the assumptions in current models, a static thermal hotspot matching the dynamical one in size and thermodynamic conditions fails to produce a deflagration wave indicating the importance of nonequilibrium loading in the criticality of nanoscale hot spots. These results provide insight into the initiation of reactive decomposition.« less

  11. Ultrafast Chemistry under Nonequilibrium Conditions and the Shock to Deflagration Transition at the Nanoscale

    SciTech Connect (OSTI)

    Wood, Mitchell A.; Cherukara, Mathew J.; Kober, Edward M.; Strachan, Alejandro

    2015-06-13

    We use molecular dynamics simulations to describe the chemical reactions following shock-induced collapse of cylindrical pores in the high-energy density material RDX. For shocks with particle velocities of 2 km/s we find that the collapse of a 40 nm diameter pore leads to a deflagration wave. Molecular collisions during the collapse lead to ultrafast, multistep chemical reactions that occur under nonequilibrium conditions. WE found that exothermic products formed during these first few picoseconds prevent the nanoscale hotspot from quenching. Within 30 ps, a local deflagration wave develops. It propagates at 0.25 km/s and consists of an ultrathin reaction zone of only ~5 nm, thus involving large temperature and composition gradients. Contrary to the assumptions in current models, a static thermal hotspot matching the dynamical one in size and thermodynamic conditions fails to produce a deflagration wave indicating the importance of nonequilibrium loading in the criticality of nanoscale hot spots. These results provide insight into the initiation of reactive decomposition.

  12. Rise time measurement for ultrafast X-ray pulses

    DOE Patents [OSTI]

    Celliers, Peter M. (Berkeley, CA); Weber, Franz A. (Oakland, CA); Moon, Stephen J. (Tracy, CA)

    2005-04-05

    A pump-probe scheme measures the rise time of ultrafast x-ray pulses. Conventional high speed x-ray diagnostics (x-ray streak cameras, PIN diodes, diamond PCD devices) do not provide sufficient time resolution to resolve rise times of x-ray pulses on the order of 50 fs or less as they are being produced by modern fast x-ray sources. Here, we are describing a pump-probe technique that can be employed to measure events where detector resolution is insufficient to resolve the event. The scheme utilizes a diamond plate as an x-ray transducer and a p-polarized probe beam.

  13. Ultrafast pulsed laser utilizing broad bandwidth laser glass

    DOE Patents [OSTI]

    Payne, S.A.; Hayden, J.S.

    1997-09-02

    An ultrafast laser uses a Nd-doped phosphate laser glass characterized by a particularly broad emission bandwidth to generate the shortest possible output pulses. The laser glass is composed primarily of P{sub 2}O{sub 5}, Al{sub 2}O{sub 3} and MgO, and possesses physical and thermal properties that are compatible with standard melting and manufacturing methods. The broad bandwidth laser glass can be used in modelocked oscillators as well as in amplifier modules. 7 figs.

  14. Rise Time Measurement for Ultrafast X-Ray Pulses

    DOE Patents [OSTI]

    Celliers, Peter M.; Weber, Franz A.; Moon, Stephen J.

    2005-04-05

    A pump-probe scheme measures the rise time of ultrafast x-ray pulses. Conventional high speed x-ray diagnostics (x-ray streak cameras, PIN diodes, diamond PCD devices) do not provide sufficient time resolution to resolve rise times of x-ray pulses on the order of 50 fs or less as they are being produced by modern fast x-ray sources. Here, we are describing a pump-probe technique that can be employed to measure events where detector resolution is insufficient to resolve the event. The scheme utilizes a diamond plate as an x-ray transducer and a p-polarized probe beam.

  15. Ultrafast laser control of backward superfluorescence towards standoff sensing

    SciTech Connect (OSTI)

    Ariunbold, Gombojav O. [Texas A and M University, College Station, Texas 77843 (United States); National University of Mongolia, Ulaanbaatar 210646 (Mongolia); Baylor University, Waco, Texas 76798 (United States); Sautenkov, Vladimir A. [Texas A and M University, College Station, Texas 77843 (United States); Joint Institute for High Temperatures, Russian Academy of Sciences, Moscow 125412 (Russian Federation); P. N. Lebedev Physical Institute, Russian Academy of Sciences, Moscow 119991 (Russian Federation); Rostovtsev, Yuri V. [University of North Texas, Denton, Texas 76203 (United States); Scully, Marlan O. [Texas A and M University, College Station, Texas 77843 (United States); Baylor University, Waco, Texas 76798 (United States); Princeton University, Princeton, New Jersey 08544 (United States)

    2014-01-13

    We study infrared backward cooperative emission in a rubidium vapor induced by ultrafast two-photon optical excitations. The laser coherent control of the backward emission is demonstrated by using a pair of 100 fs pulses with a variable time delay. The temporal variation (quantum beat) of the backward beam intensity due to interference of atomic transitions in the rubidium atomic level system 5S-5P-5D is produced and controlled. Based on the obtained experimental results, we discuss possible applications of the developed approach for creation of an effective guide star in the sodium atomic layer in the upper atmosphere (mesosphere)

  16. Ultrafast Shock Initiation of Exothermic Chemistry in Hydrogen Peroxide

    Office of Scientific and Technical Information (OSTI)

    (Journal Article) | SciTech Connect Shock Initiation of Exothermic Chemistry in Hydrogen Peroxide Citation Details In-Document Search Title: Ultrafast Shock Initiation of Exothermic Chemistry in Hydrogen Peroxide Authors: Armstrong, M R ; Zaug, J M ; Goldman, N ; Crowhurst, J C ; Howard, W M ; Carter, J A ; Kashgarian, M ; Chesser, J M ; Barbee, T W ; Bastea, S Publication Date: 2012-06-17 OSTI Identifier: 1202899 Report Number(s): LLNL-JRNL-605214 DOE Contract Number: DE-AC52-07NA27344

  17. Ultrafast pulse radiolysis using a terawatt laser wakefield accelerator

    SciTech Connect (OSTI)

    Oulianov, Dmitri A.; Crowell, Robert A.; Gosztola, David J.; Shkrob, Ilya A.; Korovyanko, Oleg J.; Rey-de-Castro, Roberto C.

    2007-03-01

    We report ultrafast pulse radiolysis transient absorption (TA) spectroscopy measurements from the Terawatt Ultrafast High Field Facility (TUHFF) at Argonne National Laboratory. TUHFF houses a 20 TW Ti:sapphire laser system that generates 2.5 nC subpicosecond pulses of multi-mega-electron-volt electrons at 10 Hz using laser wakefield acceleration. The system has been specifically optimized for kinetic TA measurements in a pump-probe fashion. This requires averaging over many shots which necessitates stable, reliable generation of electron pulses. The latter were used to generate excess electrons in pulse radiolysis of liquid water and concentrated solutions of perchloric acid. The hydronium ions in the acidic solutions react with the hydrated electrons resulting in the rapid decay of the transient absorbance at 800 nm on the picosecond time scale. Normalization of the TA signal leads to an improvement in the signal to noise ratio by a factor of 5 to 6. Due the pointing instability of the laser this improvement was limited to a 5 to 10 min acquisition period, requiring periodic recalibration and realignment. Time resolution, defined by the rise time of TA signal from hydrated electron in pulse radiolysis of liquid water, of a few picoseconds, has been demonstrated. The current time resolution is determined primarily by the physical dimensions of the sample and the detection sensitivity. Subpicosecond time resolution can be achieved by using thinner samples, more sensitive detection techniques, and improved electron beam quality.

  18. Quantum Hooke's Law to classify pulse laser induced ultrafast melting

    SciTech Connect (OSTI)

    Hu, Hao; Ding, Hepeng; Liu, Feng

    2015-02-03

    Ultrafast crystal-to-liquid phase transition induced by femtosecond pulse laser excitation is an interesting material's behavior manifesting the complexity of light-matter interaction. There exist two types of such phase transitions: one occurs at a time scale shorter than a picosecond via a nonthermal process mediated by electron-hole plasma formation; the other at a longer time scale via a thermal melting process mediated by electron-phonon interaction. However, it remains unclear what material would undergo which process and why? Here, by exploiting the property of quantum electronic stress (QES) governed by quantum Hooke's law, we classify the transitions by two distinct classes of materials: the faster nonthermal process can only occur in materials like ice having an anomalous phase diagram characterized with dTm/dP < 0, where Tm is the melting temperature and P is pressure, above a high threshold laser fluence; while the slower thermal process may occur in all materials. Especially, the nonthermal transition is shown to be induced by the QES, acting like a negative internal pressure, which drives the crystal into a super pressing state to spontaneously transform into a higher-density liquid phase. Our findings significantly advance fundamental understanding of ultrafast crystal-to-liquid phase transitions, enabling quantitative a priori predictions.

  19. UPGRADING METHANE USING ULTRA-FAST THERMAL SWING ADSORPTION

    SciTech Connect (OSTI)

    Anna Lee Tonkovich

    2004-01-01

    The purpose of this project is to design and demonstrate an approach to upgrade low-BTU methane streams from coal mines to pipeline-quality natural gas. The objective of Phase I of the project was to assess the feasibility of upgrading low-Btu methane streams using ultra-fast thermal swing adsorption (TSA) using Velocys' modular microchannel process technology. The project is on schedule and under budget. For Task 1.1, the open literature, patent information, and vendor contacts were surveyed to identify adsorbent candidates for experimental validation and subsequent demonstration in an MPT-based ultra-fast TSA separation for methane upgrading. The leading candidates for preferential adsorption of methane over nitrogen are highly microporous carbons. A Molecular Gate{trademark} zeolite from Engelhard Corporation has emerged as a candidate. For Task 1.2, experimental evaluation of adsorbents was initiated, and data were collected on carbon (MGN-101) from PICA, Inc. This carbon demonstrated a preferential capacity for methane over nitrogen, as well as a reasonable thermal swing differential capacity for a 90% methane and 10% nitrogen mixture. A similar methane swing capacity at 2 psig was measured. The mixture composition is relevant because gob gas contains nearly 85% methane and must be purified to 97% methane for pipeline quality.

  20. Quantum Hooke's Law to classify pulse laser induced ultrafast melting

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Hu, Hao; Ding, Hepeng; Liu, Feng

    2015-02-03

    Ultrafast crystal-to-liquid phase transition induced by femtosecond pulse laser excitation is an interesting material's behavior manifesting the complexity of light-matter interaction. There exist two types of such phase transitions: one occurs at a time scale shorter than a picosecond via a nonthermal process mediated by electron-hole plasma formation; the other at a longer time scale via a thermal melting process mediated by electron-phonon interaction. However, it remains unclear what material would undergo which process and why? Here, by exploiting the property of quantum electronic stress (QES) governed by quantum Hooke's law, we classify the transitions by two distinct classes ofmore » materials: the faster nonthermal process can only occur in materials like ice having an anomalous phase diagram characterized with dTm/dP < 0, where Tm is the melting temperature and P is pressure, above a high threshold laser fluence; while the slower thermal process may occur in all materials. Especially, the nonthermal transition is shown to be induced by the QES, acting like a negative internal pressure, which drives the crystal into a “super pressing” state to spontaneously transform into a higher-density liquid phase. Our findings significantly advance fundamental understanding of ultrafast crystal-to-liquid phase transitions, enabling quantitative a priori predictions.« less

  1. Dynamic Transmission Electron Microscopy

    SciTech Connect (OSTI)

    Evans, James E.; Jungjohann, K. L.; Browning, Nigel D.

    2012-10-12

    Dynamic transmission electron microscopy (DTEM) combines the benefits of high spatial resolution electron microscopy with the high temporal resolution of ultrafast lasers. The incorporation of these two components into a single instrument provides a perfect platform for in situ observations of material processes. However, previous DTEM applications have focused on observing structural changes occurring in samples exposed to high vacuum. Therefore, in order to expand the pump-probe experimental regime to more natural environmental conditions, in situ gas and liquid chambers must be coupled with Dynamic TEM. This chapter describes the current and future applications of in situ liquid DTEM to permit time-resolved atomic scale observations in an aqueous environment, Although this chapter focuses mostly on in situ liquid imaging, the same research potential exists for in situ gas experiments and the successful integration of these techniques promises new insights for understanding nanoparticle, catalyst and biological protein dynamics with unprecedented spatiotemporal resolution.

  2. Quantum chemical approach for condensed-phase thermochemistry: Proposal of a harmonic solvation model

    SciTech Connect (OSTI)

    Nakai, Hiromi; Ishikawa, Atsushi

    2014-11-07

    We propose a novel quantum chemical method, called the harmonic solvation model (HSM), for calculating thermochemical parameters in the condensed phase, particularly in the liquid phase. The HSM represents translational and rotational motions of a solute as vibrations interacting with a cavity wall of solvent molecules. As examples, the HSM and the ideal-gas model (IGM) were used for the standard formation reaction of liquid water, combustion reactions of liquid formic acid, methanol, and ethanol, vaporliquid equilibration of water and ethanol, and dissolution of gaseous CO{sub 2} in water. The numerical results confirmed the reliability and applicability of the HSM. In particular, the temperature dependence of the Gibbs energy of liquid molecules was accurately reproduced by the HSM; for example, the boiling point of water was reasonably determined using the HSM, whereas the conventional IGM treatment failed to obtain a crossing of the two Gibbs energy curves for gaseous and liquid water.

  3. Ultrafast Terahertz-Induced Response of GeSbTe Phase-Change Materials

    Office of Scientific and Technical Information (OSTI)

    (Journal Article) | SciTech Connect Journal Article: Ultrafast Terahertz-Induced Response of GeSbTe Phase-Change Materials Citation Details In-Document Search Title: Ultrafast Terahertz-Induced Response of GeSbTe Phase-Change Materials Authors: Shu, Michael J. ; Zalden, Peter ; Chen, Frank ; Weems, Ben ; Chatzakis, Ioannis ; Xiong, Feng ; Jeyasingh, Rakesh ; Hoffmann, Matthias C. ; Pop, Eric ; Wong, H.-S.Philip ; Wuttig, Matthias ; Lindenberg, Aaron M. Publication Date: 2014-07-08 OSTI

  4. Ultrafast Probes for Dirac Materials (Technical Report) | SciTech Connect

    Office of Scientific and Technical Information (OSTI)

    Ultrafast Probes for Dirac Materials Citation Details In-Document Search Title: Ultrafast Probes for Dirac Materials × You are accessing a document from the Department of Energy's (DOE) SciTech Connect. This site is a product of DOE's Office of Scientific and Technical Information (OSTI) and is provided as a public service. Visit OSTI to utilize additional information resources in energy science and technology. A paper copy of this document is also available for sale to the public from the

  5. Minute-MOFs: Ultrafast Synthesis of M2(dobpdc) Metal-Organic Frameworks

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    from Divalent Metal Oxide Colloidal Nanocrystals | Center for Gas SeparationsRelevant to Clean Energy Technologies | Blandine Jerome Minute-MOFs: Ultrafast Synthesis of M2(dobpdc) Metal-Organic Frameworks from Divalent Metal Oxide Colloidal Nanocrystals Previous Next List Maserati, Lorenzo; Meckler, Stephen M.; Li, Changyi; and Helms, Brett A. Minute-MOFs: Ultrafast Synthesis of M2(dobpdc) Metal-Organic Frameworks from Divalent Metal Oxide Colloidal Nanocrystals. Chem. Mater., ASAP (2016).

  6. Ultrafast X-ray Phase-Enhanced Microimaging for Visualizing Fuel Injection

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Process and Diesel Sprays | Department of Energy Ultrafast X-ray Phase-Enhanced Microimaging for Visualizing Fuel Injection Process and Diesel Sprays Ultrafast X-ray Phase-Enhanced Microimaging for Visualizing Fuel Injection Process and Diesel Sprays 2005 Diesel Engine Emissions Reduction (DEER) Conference Presentations and Posters PDF icon 2005_deer_wang.pdf More Documents & Publications Fuel Injection and Spray Research Using X-Ray Diagnostics Fuel Injection and Spray Research Using

  7. Ultrafast kinetics subsequent to shock compression in an oxygen-balanced

    Office of Scientific and Technical Information (OSTI)

    mixture of nitromethane and hydrogen peroxide (Journal Article) | SciTech Connect Journal Article: Ultrafast kinetics subsequent to shock compression in an oxygen-balanced mixture of nitromethane and hydrogen peroxide Citation Details In-Document Search Title: Ultrafast kinetics subsequent to shock compression in an oxygen-balanced mixture of nitromethane and hydrogen peroxide Authors: Armstrong, M R ; Zaug, J M ; Grant, C D ; Crowhurst, J C ; Bastea, S Publication Date: 2014-03-03 OSTI

  8. Ultrafast stimulated Raman parallel adiabatic passage by shaped pulses

    SciTech Connect (OSTI)

    Dridi, G.; Guerin, S.; Hakobyan, V.; Jauslin, H. R.; Eleuch, H.

    2009-10-15

    We present a general and versatile technique of population transfer based on parallel adiabatic passage by femtosecond shaped pulses. Their amplitude and phase are specifically designed to optimize the adiabatic passage corresponding to parallel eigenvalues at all times. We show that this technique allows the robust adiabatic population transfer in a Raman system with the total pulse area as low as 3{pi}, corresponding to a fluence of one order of magnitude below the conventional stimulated Raman adiabatic passage process. This process of short duration, typically picosecond and subpicosecond, is easily implementable with the modern pulse shaper technology and opens the possibility of ultrafast robust population transfer with interesting applications in quantum information processing.

  9. Ultrafast transient grating radiation to optical image converter

    DOE Patents [OSTI]

    Stewart, Richard E; Vernon, Stephen P; Steel, Paul T; Lowry, Mark E

    2014-11-04

    A high sensitivity transient grating ultrafast radiation to optical image converter is based on a fixed transmission grating adjacent to a semiconductor substrate. X-rays or optical radiation passing through the fixed transmission grating is thereby modulated and produces a small periodic variation of refractive index or transient grating in the semiconductor through carrier induced refractive index shifts. An optical or infrared probe beam tuned just below the semiconductor band gap is reflected off a high reflectivity mirror on the semiconductor so that it double passes therethrough and interacts with the radiation induced phase grating therein. A small portion of the optical beam is diffracted out of the probe beam by the radiation induced transient grating to become the converted signal that is imaged onto a detector.

  10. Identification of the dominant photochemical pathways and mechanistic insights to the ultrafast ligand exchange of Fe(CO)5 to Fe(CO)4EtOH

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Kunnus, K.; Josefsson, I.; Rajkovic, I.; Schreck, S.; Quevedo, W.; Beye, M.; Weniger, C.; Grübel, S.; Scholz, M.; Nordlund, D.; et al

    2016-02-09

    We utilized femtosecond time-resolved resonant inelastic X-ray scattering and ab initio theory to study the transient electronic structure and the photoinduced molecular dynamics of a model metal carbonyl photocatalyst Fe(CO)5 in ethanol solution. We propose mechanistic explanation for the parallel ultrafast intra-molecular spin crossover and ligation of the Fe(CO)4 which are observed following a charge transfer photoexcitation of Fe(CO)5 as reported in our previous study [Wernet et al., Nature 520, 78 (2015)]. We find that branching of the reaction pathway likely happens in the 1A1 state of Fe(CO)4. A sub-picosecond time constant of the spin crossover from 1B2 tomore » 3B2 is rationalized by the proposed 1B2 → 1A1 → 3B2 mechanism. Ultrafast ligation of the 1B2 Fe(CO)4 state is significantly faster than the spin-forbidden and diffusion limited ligation process occurring from the 3B2 Fe(CO)4 ground state that has been observed in the previous studies. We propose that the ultrafast ligation occurs via 1B2 → 1A1 → 1A' Fe(CO)4EtOH pathway and the time scale of the 1A1 Fe(CO)4 state ligation is governed by the solute-solvent collision frequency. In conclusion, our study emphasizes the importance of understanding the interaction of molecular excited states with the surrounding environment to explain the relaxation pathways of photoexcited metal carbonyls in solution.« less

  11. Extension - Upgrading Methane Using Ultra-Fast Thermal Swing Adsorption

    SciTech Connect (OSTI)

    Anna Lee Tonkovich

    2008-08-11

    The need for cost effective technologies for upgrading coal mine methane to pipeline quality natural gas is becoming ever greater. The current work presents and investigates a new approach to reduce the impact of the most costly step in the conventional technology, nitrogen rejection. The proposed approach is based on the Velocys microchannel platform, which is being developed to commercialize compact and cost efficient chemical processing technology. For this separation, ultra fast thermal swing sorption is enabled by the very high rates of heat and mass transfer inherent in microchannel processing. In a first phase of the project solid adsorbents were explored. Feasibility of ultrafast thermal swing was demonstrated but the available adsorbents had insufficient differential methane capacity to achieve the required commercial economics. In a second phase, ionic liquids were adopted as absorbents of choice, and experimental work and economic analyses, performed to gauge their potential, showed promise for this novel alternative. Final conclusions suggest that a combination of a required cost target for ionic liquids or a methane capacity increase or a combination of both is required for commercialization.

  12. ULTRAFAST OUTFLOWS: GALAXY-SCALE ACTIVE GALACTIC NUCLEUS FEEDBACK

    SciTech Connect (OSTI)

    Wagner, A. Y.; Umemura, M.; Bicknell, G. V.

    2013-01-20

    We show, using global three-dimensional grid-based hydrodynamical simulations, that ultrafast outflows (UFOs) from active galactic nuclei (AGNs) result in considerable feedback of energy and momentum into the interstellar medium (ISM) of the host galaxy. The AGN wind interacts strongly with the inhomogeneous, two-phase ISM consisting of dense clouds embedded in a tenuous, hot, hydrostatic medium. The outflow floods through the intercloud channels, sweeps up the hot ISM, and ablates and disperses the dense clouds. The momentum of the UFO is primarily transferred to the dense clouds via the ram pressure in the channel flow, and the wind-blown bubble evolves in the energy-driven regime. Any dependence on UFO opening angle disappears after the first interaction with obstructing clouds. On kpc scales, therefore, feedback by UFOs operates similarly to feedback by relativistic AGN jets. Negative feedback is significantly stronger if clouds are distributed spherically rather than in a disk. In the latter case, the turbulent backflow of the wind drives mass inflow toward the central black hole. Considering the common occurrence of UFOs in AGNs, they are likely to be important in the cosmological feedback cycles of galaxy formation.

  13. Isotopically Enriched Films and Nanostructures by Ultrafast Pulsed Laser Deposition

    SciTech Connect (OSTI)

    Peter Pronko

    2004-12-13

    This project involved a systematic study to apply newly discovered isotopic enrichment effects in laser ablation plumes to the fabrication of isotopically engineered thin films, superlattices, and nanostructures. The approach to this program involved using ultrafast lasers as a method for generating ablated plasmas that have preferentially structured isotopic content in the body of the ablation plasma plumes. In examining these results we have attempted to interpret the observations in terms of a plasma centrifuge process that is driven by the internal electro-magnetic fields of the plasma itself. The research plan involved studying the following phenomena in regard to the ablation plume and the isotopic mass distribution within it: (1) Test basic equations of steady state centrifugal motion in the ablation plasma. (2) Investigate angular distribution of ions in the ablation plasmas. (3) Examine interactions of plasma ions with self-generated magnetic fields. (3) Investigate ion to neutral ratios in the ablation plasmas. (5) Test concepts of plasma pumping. (6) Fabricate isotopically enriched nanostructures.

  14. Coherent orbital waves during an Ultrafast Photo-induced Isulator-metal Transition in a magnetoresistive manganite

    SciTech Connect (OSTI)

    ULTRAS-INFM-CNR Dipartimento di Fisica, Politecnico di Milano, Italy; Department of Physics - Cavalleri Group, Clarendon Laboratory, University of Oxford, U.K.; Correlated Electron Research Center, Tsukuba, Japan; Schoenlein, Robert William; Polli, D.; Rini, M.; Wall, S.; Schoenlein, R.W.; Tomioka, Y.; Tokura, Y.; Cerullo, G.; Cavalleri, A.

    2007-06-01

    Photo-excitation can drive strongly correlated electron insulators into competing conducting phases1,2, resulting in giant and ultrafast changes of their electronic and magnetic properties. The underlying non-equilibrium dynamics involve many degrees of freedom at once, whereby sufficiently short optical pulses can trigger the corresponding collective modes of the solid along temporally coherent pathways. The characteristic frequencies of these modes range between the few GHz of acoustic vibrations3 to the tens or even hundreds of THz for purely electronic excitations. Virtually all experiments so far have used 100 fs or longer pulses, detecting only comparatively slow lattice dynamics4,5. Here, we use sub-10-fs optical pulses to study the photo-induced insulator-metal transition in the magneto-resistive manganite Pr0.7Ca0.3MnO3. At room temperature, we find that the time-dependent pathway towards the metallic phase is accompanied by coherent 31 THz oscillations of the optical reflectivity, significantly faster than all lattice vibrations. These high-frequency oscillations are suggestive of coherent orbital waves6,7, crystal-field excitations triggered here by impulsive stimulated Raman scattering. Orbital waves are likely to be initially localized to the small polarons of this room-temperature manganite, coupling to other degrees of freedom at longer times, as photo-domains coalesce into a metallic phase.

  15. Ultrafast charge localization in a stripe-phase nickelate (Journal Article)

    Office of Scientific and Technical Information (OSTI)

    | SciTech Connect Ultrafast charge localization in a stripe-phase nickelate Citation Details In-Document Search Title: Ultrafast charge localization in a stripe-phase nickelate × You are accessing a document from the Department of Energy's (DOE) SciTech Connect. This site is a product of DOE's Office of Scientific and Technical Information (OSTI) and is provided as a public service. Visit OSTI to utilize additional information resources in energy science and technology. A paper copy of this

  16. Ultrafast terahertz-induced response of GeSbTe phase-change materials

    Office of Scientific and Technical Information (OSTI)

    (Journal Article) | SciTech Connect terahertz-induced response of GeSbTe phase-change materials Citation Details In-Document Search Title: Ultrafast terahertz-induced response of GeSbTe phase-change materials The time-resolved ultrafast electric field-driven response of crystalline and amorphous GeSbTe films has been measured all-optically, pumping with single-cycle terahertz pulses as a means of biasing phase-change materials on a sub-picosecond time-scale. Utilizing the near-band-gap

  17. Decoupling Bulk and Surface Contributions in Water- Splitting Photocatalysts by In Situ Ultrafast Spectroscopy

    SciTech Connect (OSTI)

    Appavoo, Kannatassen; Mingzhao, Liu; Black, Charles T.; Sfeir, Matthew Y.

    2015-05-10

    By performing ultrafast emission spectroscopy in an operating, bias-controlled photoelectrochemical cell, we distinguish between bulk (charge transport) and surface (chemical reaction) recombination processes in a nanostructured photocatalyst and correlate its electronic properties directly with its incident-photon-to-current efficiency.

  18. DEVELOPMENT OF NEW MID-INFRARED ULTRAFAST LASER SOURCES FOR COMPACT COHERENT X-RAY SOURCES

    SciTech Connect (OSTI)

    Sterling Backus

    2012-05-14

    In this project, we proposed to develop laser based mid-infrared lasers as a potentially robust and reliable source of ultrafast pulses in the mid-infrared region of the spectrum, and to apply this light source to generating bright, coherent, femtosecond-to-attosecond x-ray beams.

  19. Ultrafast Laser Diagnostics for Energetic-Material Ignition Mechanisms...

    Office of Scientific and Technical Information (OSTI)

    presented here. SRS a nd transient absorption diagnostics are demonstrated on static thin - film samples, and paths forward to dynamic experiments are presented. Sandia...

  20. The H2O2+OH ? HO2+H2O reaction in aqueous solution from a charge-dependent continuum model of solvation

    SciTech Connect (OSTI)

    Ginovska, Bojana; Camaioni, Donald M.; Dupuis, Michel

    2008-07-07

    We applied our recently developed protocol of the conductor-like continuum model of solvation to describe the title reaction in aqueous solution. The model has the unique feature of the molecular cavity being dependent on the atomic charges in the solute, and can be extended naturally to transition states and reaction pathways. It was used to calculate the reaction energetics and reaction rate in solution for the title reaction. The rate of reaction calculated using canonical variational transition state theory CVT in the context of the equilibrium solvation path (ESP) approximation, and including correction for tunneling through the small curvature approximation (SCT) was found to be 3.6 106 M-1 s-1, in very good agreement with experiment, These results suggest that the present protocol of the conductor-like continuum model of solvation with the charge-dependent cavity definition captures accurately the solvation effects at transition states and allows for quantitative estimates of reaction rates in solutions. This work was supported by the U.S. Department of Energy's (DOE) Office of Basic Energy Sciences, Chemical Sciences program. The Pacific Northwest National Laboratory is operated by Battelle for DOE.

  1. Ultrafast dynamics of a near-solid-density layer in an intense...

    Office of Scientific and Technical Information (OSTI)

    nm) femtosecond laser using time-resolved pump-probe Doppler spectrometry. An initial red-shift is observed in the reflected third harmonic ( 266 nm) probe pulse, which gets...

  2. Ultrafast Dynamic Response of Single Crystal PETN and Beta-HMX...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Resource Type: Conference Resource Relation: Conference: Presented at: International Detonation Symposium 15, San Francisco, CA, United States, Jul 13 - Jul 18, 2014 Research Org:...

  3. Ultrafast Power Processor for Smart Grid Power Module Development

    SciTech Connect (OSTI)

    MAITRA, ARINDAM; LITWIN, RAY; lai, Jason; Syracuse, David

    2012-12-30

    This project’s goal was to increase the switching speed and decrease the losses of the power semiconductor devices and power switch modules necessary to enable Smart Grid energy flow and control equipment such as the Ultra-Fast Power Processor. The primary focus of this project involves exploiting the new silicon-based Super-GTO (SGTO) technology and build on prototype modules already being developed. The prototype super gate-turn-off thyristor (SGTO) has been tested fully under continuously conducting and double-pulse hard-switching conditions for conduction and switching characteristics evaluation. The conduction voltage drop measurement results indicate that SGTO has excellent conduction characteristics despite inconsistency among some prototype devices. Tests were conducted with two conditions: (1) fixed gate voltage and varying anode current condition, and (2) fixed anode current and varying gate voltage condition. The conduction voltage drop is relatively a constant under different gate voltage condition. In terms of voltage drop as a function of the load current, there is a fixed voltage drop about 0.5V under zero current condition, and then the voltage drop is linearly increased with the current. For a 5-kV voltage blocking device that may operate under 2.5-kV condition, the projected voltage drop is less than 2.5 V under 50-A condition, or 0.1%. If the device is adopted in a converter operating under soft-switching condition, then the converter can achieve an ultrahigh efficiency, typically above 99%. The two-pulse switching test results indicate that SGTO switching speed is very fast. The switching loss is relatively low as compared to that of the insulated-gate-bipolar-transistors (IGBTs). A special phenomenon needs to be noted is such a fast switching speed for the high-voltage switching tends to create an unexpected Cdv/dt current, which reduces the turn-on loss because the dv/dt is negative and increases the turn-off loss because the dv/dt is positive. As a result, the turn-on loss at low current is quite low, and the turn-off loss at low current is relatively high. The phenomenon was verified with junction capacitance measurement along with the dv/dt calculation. Under 2-kV test condition, the turn-on and turn-off losses at 25-A is about 3 and 9 mJ, respectively. As compared to a 4.5-kV, 60-A rated IGBT, which has turn-on and turn-off losses about 25 and 20 mJ under similar test condition, the SGTO shows significant switching loss reduction. The switching loss depends on the switching frequency, but under hard-switching condition, the SGTO is favored to the IGBT device. The only concern is during low current turn-on condition, there is a voltage bump that can translate to significant power loss and associated heat. The reason for such a current bump is not known from this study. It is necessary that the device manufacturer perform though test and provide the answer so the user can properly apply SGTO in pulse-width-modulated (PWM) converter and inverter applications.

  4. Time-domain sampling of x-ray pulses using an ultrafast sample response

    SciTech Connect (OSTI)

    Gaal, P.; Shayduk, R.; Schick, D.; Herzog, M.; Bojahr, A.; Goldshteyn, J.; Navirian, H. A.; Leitenberger, W.; Vrejoiu, I.; Khakhulin, D.; Wulff, M.; Bargheer, M.

    2012-12-10

    We employ the ultrafast response of a 15.4 nm thin SrRuO{sub 3} layer grown epitaxially on a SrTiO{sub 3} substrate to perform time-domain sampling of an x-ray pulse emitted from a synchrotron storage ring. Excitation of the sample with an ultrashort laser pulse triggers coherent expansion and compression waves in the thin layer, which turn the diffraction efficiency on and off at a fixed Bragg angle during 5 ps. This is significantly shorter than the duration of the synchrotron x-ray pulse of 100 ps. Cross-correlation measurements of the ultrafast sample response and the synchrotron x-ray pulse allow to reconstruct the x-ray pulse shape.

  5. Scientists Track Ultrafast Formation of Catalyst with X-ray Laser | U.S.

    Office of Science (SC) Website

    DOE Office of Science (SC) Scientists Track Ultrafast Formation of Catalyst with X-ray Laser Basic Energy Sciences (BES) BES Home About Research Facilities Science Highlights Benefits of BES Funding Opportunities Basic Energy Sciences Advisory Committee (BESAC) Community Resources Contact Information Basic Energy Sciences U.S. Department of Energy SC-22/Germantown Building 1000 Independence Ave., SW Washington, DC 20585 P: (301) 903-3081 F: (301) 903-6594 E: Email Us More Information »

  6. Ultrafast Terahertz-Induced Response of GeSbTe Phase-Change Materials

    Office of Scientific and Technical Information (OSTI)

    (Journal Article) | SciTech Connect Terahertz-Induced Response of GeSbTe Phase-Change Materials Citation Details In-Document Search Title: Ultrafast Terahertz-Induced Response of GeSbTe Phase-Change Materials Authors: Shu, Michael J. ; Zalden, Peter ; Chen, Frank ; Weems, Ben ; Chatzakis, Ioannis ; Xiong, Feng ; Jeyasingh, Rakesh ; Hoffmann, Matthias C. ; Pop, Eric ; Wong, H.-S.Philip ; Wuttig, Matthias ; Lindenberg, Aaron M. Publication Date: 2014-07-08 OSTI Identifier: 1136695 Report

  7. Ablation experiment and threshold calculation of titanium alloy irradiated by ultra-fast pulse laser

    SciTech Connect (OSTI)

    Zheng, Buxiang; Jiang, Gedong; Wang, Wenjun Wang, Kedian; Mei, Xuesong; State Key Laboratory for Manufacturing Systems Engineering, Xi'an Jiaotong University, Xi'an 710054

    2014-03-15

    The interaction between an ultra-fast pulse laser and a material's surface has become a research hotspot in recent years. Micromachining of titanium alloy with an ultra-fast pulse laser is a very important research direction, and it has very important theoretical significance and application value in investigating the ablation threshold of titanium alloy irradiated by ultra-fast pulse lasers. Irradiated by a picosecond pulse laser with wavelengths of 1064 nm and 532 nm, the surface morphology and feature sizes, including ablation crater width (i.e. diameter), ablation depth, ablation area, ablation volume, single pulse ablation rate, and so forth, of the titanium alloy were studied, and their ablation distributions were obtained. The experimental results show that titanium alloy irradiated by a picosecond pulse infrared laser with a 1064 nm wavelength has better ablation morphology than that of the green picosecond pulse laser with a 532 nm wavelength. The feature sizes are approximately linearly dependent on the laser pulse energy density at low energy density and the monotonic increase in laser pulse energy density. With the increase in energy density, the ablation feature sizes are increased. The rate of increase in the feature sizes slows down gradually once the energy density reaches a certain value, and gradually saturated trends occur at a relatively high energy density. Based on the linear relation between the laser pulse energy density and the crater area of the titanium alloy surface, and the Gaussian distribution of the laser intensity on the cross section, the ablation threshold of titanium alloy irradiated by an ultra-fast pulse laser was calculated to be about 0.109 J/cm{sup 2}.

  8. The Behavior of Hydrogen Under Extreme Conditions on Ultrafast Timescales (A "Life at the Frontiers of Energy Research" contest entry from the 2011 Energy Frontier Research Centers (EFRCs) Summit and Forum)

    ScienceCinema (OSTI)

    Mao, Ho-kwang (Director, Center for Energy Frontier Research in Extreme Environments); EFree Staff

    2011-11-02

    'The Behavior of Hydrogen Under Extreme Conditions on Ultrafast Timescales ' was submitted by the Center for Energy Frontier Research in Extreme Environments (EFree) to the 'Life at the Frontiers of Energy Research' video contest at the 2011 Science for Our Nation's Energy Future: Energy Frontier Research Centers (EFRCs) Summit and Forum. Twenty-six EFRCs created short videos to highlight their mission and their work. EFree is directed by Ho-kwang Mao at the Carnegie Institute of Washington and is a partnership of scientists from thirteen institutions.The Office of Basic Energy Sciences in the U.S. Department of Energy's Office of Science established the 46 Energy Frontier Research Centers (EFRCs) in 2009. These collaboratively-organized centers conduct fundamental research focused on 'grand challenges' and use-inspired 'basic research needs' recently identified in major strategic planning efforts by the scientific community. The overall purpose is to accelerate scientific progress toward meeting the nation's critical energy challenges. The mission of Energy Frontier Research in Extreme Environments is 'to accelerate the discovery and creation of energy-relevant materials using extreme pressures and temperatures.' Research topics are: catalysis (CO{sub 2}, water), photocatalysis, solid state lighting, optics, thermelectric, phonons, thermal conductivity, solar electrodes, fuel cells, superconductivity, extreme environment, radiation effects, defects, spin dynamics, CO{sub 2} (capture, convert, store), greenhouse gas, hydrogen (fuel, storage), ultrafast physics, novel materials synthesis, and defect tolerant materials.

  9. Following the dynamics of matter with femtosecond precision using the X-ray streaking method

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    David, C.; Karvinen, P.; Sikorski, M.; Song, S.; Vartiainen, I.; Milne, C. J.; Mozzanica, A.; Kayser, Y.; Diaz, A.; Mohacsi, I.; et al

    2015-01-06

    X-ray Free Electron Lasers (FELs) can produce extremely intense and very short pulses, down to below 10 femtoseconds (fs). Among the key applications are ultrafast time-resolved studies of dynamics of matter by observing responses to fast excitation pulses in a pump-probe manner. Detectors with sufficient time resolution for observing these processes are not available. Therefore, such experiments typically measure a sample's full dynamics by repeating multiple pump-probe cycles at different delay times. This conventional method assumes that the sample returns to an identical or very similar state after each cycle. Here we describe a novel approach that can provide amore » time trace of responses following a single excitation pulse, jitter-free, with fs timing precision. We demonstrate, in an X-ray diffraction experiment, how it can be applied to the investigation of ultrafast irreversible processes.« less

  10. Ultrafast spectroscopy of super high frequency mechanical modes of doubly clamped beams

    SciTech Connect (OSTI)

    Ristow, Oliver; Merklein, Moritz; Grossmann, Martin; Hettich, Mike; Schubert, Martin; Bruchhausen, Axel; Scheer, Elke; Dekorsy, Thomas; Barretto, Elaine C. S.; Grebing, Jochen; Erbe, Artur; Mounier, Denis; Gusev, Vitalyi

    2013-12-02

    We use ultrafast pump-probe spectroscopy to study the mechanical vibrations in the time domain of doubly clamped silicon nitride beams. Beams with two different clamping conditions are investigated. Finite element method calculations are performed to analyse the mode spectra of both structures. By calculating the strain integral on the surface of the resonators, we are able to reproduce the effect of the detection mechanism and identify all the measured modes. We show that our spectroscopy technique combined with our modelling tools allow the investigation of several different modes in the super high frequency range (3-30?GHz) and above, bringing more information about the vibration modes of nanomechanical resonators.

  11. Ultrafast Terahertz-Induced Response of GeSbTe Phase-Change Materials

    Office of Scientific and Technical Information (OSTI)

    (Journal Article) | SciTech Connect Terahertz-Induced Response of GeSbTe Phase-Change Materials Citation Details In-Document Search Title: Ultrafast Terahertz-Induced Response of GeSbTe Phase-Change Materials × You are accessing a document from the Department of Energy's (DOE) SciTech Connect. This site is a product of DOE's Office of Scientific and Technical Information (OSTI) and is provided as a public service. Visit OSTI to utilize additional information resources in energy science and

  12. H.sub.2O doped WO.sub.3, ultra-fast, high-sensitivity hydrogen sensors

    DOE Patents [OSTI]

    Liu, Ping (Denver, CO); Tracy, C. Edwin (Golden, CO); Pitts, J. Roland (Lakewood, CO); Lee, Se-Hee (Lakewood, CO)

    2011-03-22

    An ultra-fast response, high sensitivity structure for optical detection of low concentrations of hydrogen gas, comprising: a substrate; a water-doped WO.sub.3 layer coated on the substrate; and a palladium layer coated on the water-doped WO.sub.3 layer.

  13. Possible Demonstration of a Polaronic Bose-Einstein(-Mott) Condensate in UO2(+x) by Ultrafast THz Spectroscopy and Microwave Dissipation

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Conradson, Steven D.; Gilbertson, Steven M.; Daifuku, Stephanie L.; Kehl, Jeffrey A.; Durakiewicz, Tomasz; Andersson, David A.; Bishop, Alan R.; Byler, Darrin D.; Maldonado, Pablo; Oppeneer, Peter M.; et al

    2015-10-16

    Bose-Einstein condensates (BECs) composed of polarons would be an advance because they would combine coherently charge, spin, and a crystal lattice. Following our earlier report of unique structural and spectroscopic properties, we now identify potentially definitive evidence for polaronic BECs in photo- and chemically doped UO2(+x) on the basis of exceptional coherence in the ultrafast time dependent terahertz absorption and microwave spectroscopy results that show collective behavior including dissipation patterns whose precedents are condensate vortex and defect disorder and condensate excitations. Furthermore, that some of these signatures of coherence in an atom-based system extend to ambient temperature suggests a novelmore » mechanism that could be a synchronized, dynamical, disproportionation excitation, possibly via the solid state analog of a Feshbach resonance that promotes the coherence. Such a mechanism would demonstrate that the use of ultra-low temperatures to establish the BEC energy distribution is a convenience rather than a necessity, with the actual requirement for the particles being in the same state that is not necessarily the ground state attainable by other means. Interestingly, a macroscopic quantum object created by chemical doping that can persist to ambient temperature and resides in a bulk solid would be revolutionary in a number of scientific and technological fields.« less

  14. Possible Demonstration of a Polaronic Bose-Einstein(-Mott) Condensate in UO2(+x) by Ultrafast THz Spectroscopy and Microwave Dissipation

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Conradson, Steven D.; Gilbertson, Steven M.; Daifuku, Stephanie L.; Kehl, Jeffrey A.; Durakiewicz, Tomasz; Andersson, David A.; Bishop, Alan R.; Byler, Darrin D.; Maldonado, Pablo; Oppeneer, Peter M.; et al

    2015-10-16

    Bose-Einstein condensates (BECs) composed of polarons would be an advance because they would combine coherently charge, spin, and a crystal lattice. Following our earlier report of unique structural and spectroscopic properties, we now identify potentially definitive evidence for polaronic BECs in photo- and chemically doped UO2(+x) on the basis of exceptional coherence in the ultrafast time dependent terahertz absorption and microwave spectroscopy results that show collective behavior including dissipation patterns whose precedents are condensate vortex and defect disorder and condensate excitations. Furthermore, that some of these signatures of coherence in an atom-based system extend to ambient temperature suggests a novelmore »mechanism that could be a synchronized, dynamical, disproportionation excitation, possibly via the solid state analog of a Feshbach resonance that promotes the coherence. Such a mechanism would demonstrate that the use of ultra-low temperatures to establish the BEC energy distribution is a convenience rather than a necessity, with the actual requirement for the particles being in the same state that is not necessarily the ground state attainable by other means. Interestingly, a macroscopic quantum object created by chemical doping that can persist to ambient temperature and resides in a bulk solid would be revolutionary in a number of scientific and technological fields.« less

  15. Accurate static and dynamic properties of liquid electrolytes for Li-ion batteries from ab initio molecular dynamics

    SciTech Connect (OSTI)

    Ganesh, P.; Jiang, D.; Kent, P.R.C.

    2011-03-31

    Lithium-ion batteries have the potential to revolutionize the transportation industry, as they did for wireless communication. A judicious choice of the liquid electrolytes used in these systems is required to achieve a good balance among high-energy storage, long cycle life and stability, and fast charging. Ethylene-carbonate (EC) and propylene-carbonate (PC) are popular electrolytes. However, to date, almost all molecular-dynamics simulations of these fluids rely on classical force fields, while a complete description of the functionality of Li-ion batteries will eventually require quantum mechanics. We perform accurate ab initio molecular-dynamics simulations of ethylene- and propylene-carbonate with LiPF6 at experimental concentrations to build solvation models which explain available neutron scattering and nuclear magnetic resonance (NMR) results and to compute Li-ion solvation energies and diffusion constants. Our results suggest some similarities between the two liquids as well as some important differences. Simulations also provide useful insights into formation of solid-electrolyte interphases in the presence of electrodes in conventional Li-ion batteries.

  16. Accurate static and dynamic properties of liquid-electrolytes for Li-ion batteries from ab initio molecular dynamics

    SciTech Connect (OSTI)

    Ganesh, Panchapakesan; Jiang, Deen; Kent, Paul R

    2011-01-01

    Lithium-ion batteries have the potential to revolutionize the transportation industry, as they did for wireless communication. A judicious choice of the liquid electrolytes used in these systems is required to achieve a good balance among high-energy storage, long cycle life and stability, and fast charging. Ethylene-carbonate (EC) and propylene-carbonate (PC) are popular electrolytes. However, to date, almost all molecular-dynamics simulations of these fluids rely on classical force fields, while a complete description of the functionality of Li-ion batteries will eventually require quantum mechanics. We perform accurate ab initio molecular-dynamics simulations of ethylene- and propylene-carbonate with LiPF6 at experimental concentrations to build solvation models which explain available neutron scattering and nuclear magnetic resonance (NMR) results and to compute Li-ion solvation energies and diffusion constants. Our results suggest some similarities between the two liquids as well as some important differences. Simulations also provide useful insights into formation of solid-electrolyte interphases in the presence of electrodes in conventional Li-ion batteries.

  17. Effective Analysis of NGS Metagenomic Data with Ultra-Fast Clustering Algorithms (MICW - Metagenomics Informatics Challenges Workshop: 10K Genomes at a Time)

    ScienceCinema (OSTI)

    Li, Weizhong [San Diego Supercomputer Center

    2013-01-22

    San Diego Supercomputer Center's Weizhong Li on "Effective Analysis of NGS Metagenomic Data with Ultra-fast Clustering Algorithms" at the Metagenomics Informatics Challenges Workshop held at the DOE JGI on October 12-13, 2011.

  18. Probing the Early Stages of Solvation of cis-Pinate Dianions by Water, Acetonitrile, and Methanol: A Photoelectron Spectroscopy and Theoretical Study

    SciTech Connect (OSTI)

    Hou, Gao-Lei; Kong, Xiang-Tao; Valiev, Marat; Jiang, Ling; Wang, Xue B.

    2016-01-01

    Cis-pinic acid is one of the most important oxidation products of α-pinene – a key monoterpene compound in biogenic emission processes affecting the atmosphere. Molecular level understanding of interactions involved in the cluster formations around cis-pinic acid is an important and necessary prerequisite toward ascertaining its role in the aerosol formation processes. In this work, we studied the structures and energetics of the solvated clusters of cis-pinate (cis-PA²⁻), the doubly deprotonated dicarboxylate of cis-pinic acid, with H₂O, CH₃OH, and CH₃CN by negative ion photoelectron spectroscopy and ab initio theoretical calculations. We found that cis-PA²⁻ prefers being solvated alternately on the two -CO₂⁻ groups with increase of solvent coverage, a well-known solvation pattern that has been observed in microhydrated linear dicarboxylate dianion (DCn²⁻) clusters. Experiments and calculations further reveal an intriguing feature for the existence of the asymmetric type isomers for cis-PA2–(H2O)2 and cis-PA²⁻(CH₃OH)₂, in which both solvent molecules interact with only one of the -CO²⁻ groups – a phenomena that has not been observed in DCn²⁻ water clusters and exhibits the subtle effect of the rigid four-membered carbon ring brought in on the cis-PA²⁻ solvation. The dominant interactions between cis-PA²⁻ and solvent molecules are forming bidentate O–···H–O H-bonds for H₂O, O–···H–O and O–···H–C H-bonds for CH₃OH, and tridentate O–···H–C H-bonds for CH₃CN. The formation of inter-solvent H-bonds between H₂O and CH₃CN is found to be favorable in mixed solvent clusters, distinctly different from that between H₂O and CH₃OH. These findings have important implications for understanding the mechanism of cluster growth and nucleation of atmospheric organic aerosols and the nature of structure-function relationship of proteins containing carboxylate groups under various solvent environments.

  19. Ultrafast terahertz-induced response of GeSbTe phase-change materials

    SciTech Connect (OSTI)

    Shu, Michael J.; Zalden, Peter; Chen, Frank; Weems, Ben; Chatzakis, Ioannis; Xiong, Feng; Jeyasingh, Rakesh; Pop, Eric; Philip Wong, H.-S.; Hoffmann, Matthias C.; Wuttig, Matthias; Lindenberg, Aaron M.

    2014-06-23

    The time-resolved ultrafast electric field-driven response of crystalline and amorphous GeSbTe films has been measured all-optically, pumping with single-cycle terahertz pulses as a means of biasing phase-change materials on a sub-picosecond time-scale. Utilizing the near-band-gap transmission as a probe of the electronic and structural response below the switching threshold, we observe a field-induced heating of the carrier system and resolve the picosecond-time-scale energy relaxation processes and their dependence on the sample annealing condition in the crystalline phase. In the amorphous phase, an instantaneous electroabsorption response is observed, quadratic in the terahertz field, followed by field-driven lattice heating, with Ohmic behavior up to 200?kV/cm.

  20. Efficient terahertz-wave generation and its ultrafast optical modulation in charge ordered organic ferroelectrics

    SciTech Connect (OSTI)

    Itoh, Hirotake Iwai, Shinichiro; Itoh, Keisuke; Goto, Kazuki; Yamamoto, Kaoru; Yakushi, Kyuya

    2014-04-28

    Efficient terahertz (THz) wave generation in strongly correlated organic compounds ?-(ET){sub 2}I{sub 3} and ??-(ET){sub 2}IBr{sub 2} (ET:bis(ethylenedithio)-tetrathiafulvalene) was demonstrated. The spontaneous polarization induced by charge ordering or electronic ferroelectricity was revealed to trigger the THz-wave generation via optical rectification; the estimated 2nd-order nonlinear optical susceptibility for ?-(ET){sub 2}I{sub 3} is over 70 times larger than that for prototypical THz-source ZnTe. Ultrafast (<1 ps) and sensitive (?40%) photoresponse of the THz wave was observed for ?-(ET){sub 2}I{sub 3}, which is attributable to photoinduced quenching of the polarization accompanied by insulator(ferroelectric)-to-metal transition. Modulation of the THz wave was observed for ??-(ET){sub 2}IBr{sub 2} upon the poling procedure, indicating the alignment of polar domains.

  1. Terahertz Spectroscopy of Low-Dimensional Nanomaterials: Nonlinear Emission and Ultrafast Electrodynamics

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Luo, Liang; Wang, Jigang

    2016-01-01

    Nonlinear and non-equilibrium properties of low-dimensional quantum materials are fundamental in nanoscale science yet transformative in nonlinear imaging/photonic technology today. These have been poorly addressed in many nano-materials despite of their well-established equilibrium optical and transport properties. The development of ultrafast terahertz (THz) sources and nonlinear spectroscopy tools facilitates understanding these issues and reveals a wide range of novel nonlinear and quantum phenomena that are not expected in bulk solids or atoms. In this paper, we discuss our recent discoveries in two model photonic and electronic nanostructures to solve two outstanding questions: (1) how to create nonlinear broadband terahertz emittersmore » using deeply subwavelength nanoscale meta-atom resonators? (2) How to access one-dimensional (1D) dark excitons and their non-equilibrium correlated states in single-walled carbon nanotubes (SWMTs)?« less

  2. Photodissociation dynamics of hydroxybenzoic acids

    SciTech Connect (OSTI)

    Yang Yilin; Dyakov, Yuri; Lee, Y. T.; Ni, Chi-Kung; Sun Yilun; Hu Weiping

    2011-01-21

    Aromatic amino acids have large UV absorption cross-sections and low fluorescence quantum yields. Ultrafast internal conversion, which transforms electronic excitation energy to vibrational energy, was assumed to account for the photostability of amino acids. Recent theoretical and experimental investigations suggested that low fluorescence quantum yields of phenol (chromophore of tyrosine) are due to the dissociation from a repulsive excited state. Radicals generated from dissociation may undergo undesired reactions. It contradicts the observed photostability of amino acids. In this work, we explored the photodissociation dynamics of the tyrosine chromophores, 2-, 3- and 4-hydroxybenzoic acid in a molecular beam at 193 nm using multimass ion imaging techniques. We demonstrated that dissociation from the excited state is effectively quenched for the conformers of hydroxybenzoic acids with intramolecular hydrogen bonding. Ab initio calculations show that the excited state and the ground state potential energy surfaces change significantly for the conformers with intramolecular hydrogen bonding. It shows the importance of intramolecular hydrogen bond in the excited state dynamics and provides an alternative molecular mechanism for the photostability of aromatic amino acids upon irradiation of ultraviolet photons.

  3. Influence of Domain Wall Pinning on the Dynamic Behavior of Magnetic

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Vortices Influence of Domain Wall Pinning on the Dynamic Behavior of Magnetic Vortices Influence of Domain Wall Pinning on the Dynamic Behavior of Magnetic Vortices Print Wednesday, 27 August 2008 00:00 Soft magnetic, micron-sized thin-film structures with magnetic vortices are intriguing systems that may one day be used in ultrafast computer memories. In such systems, the otherwise in-plane magnetization turns perpendicular to the plane at the center of the vortex, forming the vortex core.

  4. Water around fullerene shape amphiphiles: A molecular dynamics simulation study of hydrophobic hydration

    SciTech Connect (OSTI)

    Varanasi, S. R. E-mail: guskova@ipfdd.de; John, A.; Guskova, O. A. E-mail: guskova@ipfdd.de; Sommer, J.-U.

    2015-06-14

    Fullerene C{sub 60} sub-colloidal particle with diameter ?1 nm represents a boundary case between small and large hydrophobic solutes on the length scale of hydrophobic hydration. In the present paper, a molecular dynamics simulation is performed to investigate this complex phenomenon for bare C{sub 60} fullerene and its amphiphilic/charged derivatives, so called shape amphiphiles. Since most of the unique properties of water originate from the pattern of hydrogen bond network and its dynamics, spatial, and orientational aspects of water in solvation shells around the solute surface having hydrophilic and hydrophobic regions are analyzed. Dynamical properties such as translational-rotational mobility, reorientational correlation and occupation time correlation functions of water molecules, and diffusion coefficients are also calculated. Slower dynamics of solvent moleculeswater retardationin the vicinity of the solutes is observed. Both the topological properties of hydrogen bond pattern and the dangling OH groups that represent surface defects in water network are monitored. The fraction of such defect structures is increased near the hydrophobic cap of fullerenes. Some dry regions of C{sub 60} are observed which can be considered as signatures of surface dewetting. In an effort to provide molecular level insight into the thermodynamics of hydration, the free energy of solvation is determined for a family of fullerene particles using thermodynamic integration technique.

  5. Drama in Dynamics: Boom, Splash, and Speed

    SciTech Connect (OSTI)

    Heather Marie Netzloff

    2004-12-19

    The full nature of chemistry and physics cannot be captured by static calculations alone. Dynamics calculations allow the simulation of time-dependent phenomena. This facilitates both comparisons with experimental data and the prediction and interpretation of details not easily obtainable from experiments. Simulations thus provide a direct link between theory and experiment, between microscopic details of a system and macroscopic observed properties. Many types of dynamics calculations exist. The most important distinction between the methods and the decision of which method to use can be described in terms of the size and type of molecule/reaction under consideration and the type and level of accuracy required in the final properties of interest. These considerations must be balanced with available computational codes and resources as simulations to mimic ''real-life'' may require many time steps. As indicated in the title, the theme of this thesis is dynamics. The goal is to utilize the best type of dynamics for the system under study while trying to perform dynamics in the most accurate way possible. As a quantum chemist, this involves some level of first principles calculations by default. Very accurate calculations of small molecules and molecular systems are now possible with relatively high-level ab initio quantum chemistry. For example, a quantum chemical potential energy surface (PES) can be developed ''on-the-fly'' with dynamic reaction path (DRP) methods. In this way a classical trajectory is developed without prior knowledge of the PES. In order to treat solvation processes and the condensed phase, large numbers of molecules are required, especially in predicting bulk behavior. The Effective Fragment Potential (EFP) method for solvation decreases the cost of a fully quantum mechanical calculation by dividing a chemical system into an ab initio region that contains the solute and an ''effective fragment'' region that contains the remaining solvent molecules. But, despite the reduced cost relative to fully QM calculations, the EFP method, due to its complex, QM-based potential, does require more computation time than simple interaction potentials, especially when the method is used for large scale molecular dynamics simulations. Thus, the EFP method was parallelized to facilitate these calculations within the quantum chemistry program GAMESS. The EFP method provides relative energies and structures that are in excellent agreement with the analogous fully quantum results for small water clusters. The ability of the method to predict bulk water properties with a comparable accuracy is assessed by performing EFP molecular dynamics simulations. Molecular dynamics simulations can provide properties that are directly comparable with experimental results, for example radial distribution functions. The molecular PES is a fundamental starting point for chemical reaction dynamics. Many methods can be used to obtain a PES; for example, assuming a global functional form for the PES or, as mentioned above, performing ''on-the-fly'' dynamics with Al or semi-empirical calculations at every molecular configuration. But as the size of the system grows, using electronic structure theory to build a PES and, therefore, study reaction dynamics becomes virtually impossible. The program Grow builds a PES as an interpolation of Al data; the goal is to attempt to produce an accurate PES with the smallest number of Al calculations. The Grow-GAMESS interface was developed to obtain the Al data from GAMESS. Classical or quantum dynamics can be performed on the resulting surface. The interface includes the novel capability to build multi-reference PESs; these types of calculations are applicable to problems ranging from atmospheric chemistry to photochemical reaction mechanisms in organic and inorganic chemistry to fundamental biological phenomena such as photosynthesis.

  6. Surface modified CFx cathode material for ultrafast discharge and high energy density

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Dai, Yang; Zhu, Yimei; Cai, Sendan; Wu, Lijun; Yang, Weijing; Xie, Jingying; Wen, Wen; Zheng, Jin-Cheng; Zheng, Yi

    2014-11-10

    Li/CFx primary possesses the highest energy density of 2180 W h kg⁻¹ among all primary lithium batteries. However, a key limitation for the utility of this type of battery is in its poor rate capability because the cathode material, CFx, is an intrinsically poor electronic conductor. Here, we report on our development of a controlled process of surface de-fluorination under mild hydrothermal conditions to modify the highly fluorinated CFx. The modified CFx, consisting of an in situ generated shell component of F-graphene layers, possesses good electronic conductivity and removes the transporting barrier for lithium ions, yielding a high-capacity performance andmore » an excellent rate-capability. Indeed, a capacity of 500 mA h g⁻¹ and a maximum power density of 44 800 W kg⁻¹ can be realized at the ultrafast rate of 30 C (24 A g⁻¹), which is over one order of magnitude higher than that of the state-of-the-art primary lithium-ion batteries.« less

  7. Phase-contrast imaging using ultrafast x-rays in laser-shocked materials

    SciTech Connect (OSTI)

    Workman, Jonathan B; Cobble, James A; Flippo, Kirk; Gautier, Donald C; Montgomery, David S; Offermann, Dustin T

    2010-01-01

    High-energy x-rays, > 10-keV, can be efficiently produced from ultrafast laser target interactions with many applications to dense target materials in Inertial Confinement Fusion (ICF) and High-Energy Density Physics (HEDP). These same x-rays can also be applied to measurements of low-density materials inside high-density hohlraum environments. In the experiments presented, high-energy x-ray images of laser-shocked polystyrene are produced through phase contrast imaging. The plastic targets are nominally transparent to traditional x-ray absorption but show detailed features in regions of high density gradients due to refractive effects often called phase contrast imaging. The 200-TW Trident laser is used both to produce the x-ray source and to shock the polystyrene target. X-rays at 17-keV produced from 2-ps, 100-J laser interactions with a 12-micron molybdenum wire are used to produce a small source size, required for optimizing refractive effects. Shocks are driven in the 1-mm thick polystyrene target using 2-ns, 250-J, 532-nm laser drive with phase plates. X-ray images of shocks compare well to 1-D hydro calculations, HELIOS-CR.

  8. Ultrafast nanolaser device for detecting cancer in a single live cell.

    SciTech Connect (OSTI)

    Gourley, Paul Lee; McDonald, Anthony Eugene

    2007-11-01

    Emerging BioMicroNanotechnologies have the potential to provide accurate, realtime, high throughput screening of live tumor cells without invasive chemical reagents when coupled with ultrafast laser methods. These optically based methods are critical to advancing early detection, diagnosis, and treatment of disease. The first year goals of this project are to develop a laser-based imaging system integrated with an in- vitro, live-cell, micro-culture to study mammalian cells under controlled conditions. In the second year, the system will be used to elucidate the morphology and distribution of mitochondria in the normal cell respiration state and in the disease state for normal and disease states of the cell. In this work we designed and built an in-vitro, live-cell culture microsystem to study mammalian cells under controlled conditions of pH, temp, CO2, Ox, humidity, on engineered material surfaces. We demonstrated viability of cell culture in the microsystem by showing that cells retain healthy growth rates, exhibit normal morphology, and grow to confluence without blebbing or other adverse influences of the material surfaces. We also demonstrated the feasibility of integrating the culture microsystem with laser-imaging and performed nanolaser flow spectrocytometry to carry out analysis of the cells isolated mitochondria.

  9. Surface modified CFx cathode material for ultrafast discharge and high energy density

    SciTech Connect (OSTI)

    Dai, Yang; Zhu, Yimei; Cai, Sendan; Wu, Lijun; Yang, Weijing; Xie, Jingying; Wen, Wen; Zheng, Jin-Cheng; Zheng, Yi

    2014-11-10

    Li/CFx primary possesses the highest energy density of 2180 W h kg? among all primary lithium batteries. However, a key limitation for the utility of this type of battery is in its poor rate capability because the cathode material, CFx, is an intrinsically poor electronic conductor. Here, we report on our development of a controlled process of surface de-fluorination under mild hydrothermal conditions to modify the highly fluorinated CFx. The modified CFx, consisting of an in situ generated shell component of F-graphene layers, possesses good electronic conductivity and removes the transporting barrier for lithium ions, yielding a high-capacity performance and an excellent rate-capability. Indeed, a capacity of 500 mA h g? and a maximum power density of 44 800 W kg? can be realized at the ultrafast rate of 30 C (24 A g?), which is over one order of magnitude higher than that of the state-of-the-art primary lithium-ion batteries.

  10. Quantum dynamics of solid Ne upon photo-excitation of a NO impurity: A Gaussian wave packet approach

    SciTech Connect (OSTI)

    Unn-Toc, W.; Meier, C.; Halberstadt, N.; Uranga-Pina, Ll.; Rubayo-Soneira, J.

    2012-08-07

    A high-dimensional quantum wave packet approach based on Gaussian wave packets in Cartesian coordinates is presented. In this method, the high-dimensional wave packet is expressed as a product of time-dependent complex Gaussian functions, which describe the motion of individual atoms. It is applied to the ultrafast geometrical rearrangement dynamics of NO doped cryogenic Ne matrices after femtosecond laser pulse excitation. The static deformation of the solid due to the impurity as well as the dynamical response after femtosecond excitation are analyzed and compared to reduced dimensionality studies. The advantages and limitations of this method are analyzed in the perspective of future applications to other quantum solids.

  11. Modeling nanoscale hydrodynamics by smoothed dissipative particle dynamics

    SciTech Connect (OSTI)

    Lei, Huan; Mundy, Christopher J.; Schenter, Gregory K.; Voulgarakis, Nikolaos

    2015-05-21

    Thermal fluctuation and hydrophobicity are two hallmarks of fluid hydrodynamics on the nano-scale. It is a challenge to consistently couple the small length and time scale phenomena associated with molecular interaction with larger scale phenomena. The development of this consistency is the essence of mesoscale science. In this study, we develop a nanoscale fluid model based on smoothed dissipative particle dynamics that accounts for the phenomena of associated with density fluctuations and hydrophobicity. We show consistency in the fluctuation spectrum across scales. In doing so, it is necessary to account for finite fluid particle size. Furthermore, we demonstrate that the present model can capture of the void probability and solvation free energy of apolar particles of different sizes. The present fluid model is well suited for a understanding emergent phenomena in nano-scale fluid systems.

  12. Solvation of fluoro-acetonitrile in water by 2D-IR spectroscopy: A combined experimental-computational study

    SciTech Connect (OSTI)

    Cazade, Pierre-Andr; Das, Akshaya K.; Tran, Halina; Klsi, Felix; Hamm, Peter; Bereau, Tristan; Meuwly, Markus

    2015-06-07

    The solvent dynamics around fluorinated acetonitrile is characterized by 2-dimensional infrared spectroscopy and atomistic simulations. The lineshape of the linear infrared spectrum is better captured by semiempirical (density functional tight binding) mixed quantum mechanical/molecular mechanics simulations, whereas force field simulations with multipolar interactions yield lineshapes that are significantly too narrow. For the solvent dynamics, a relatively slow time scale of 2 ps is found from the experiments and supported by the mixed quantum mechanical/molecular mechanics simulations. With multipolar force fields fitted to the available thermodynamical data, the time scale is considerably fasteron the 0.5 ps time scale. The simulations provide evidence for a well established CFHOH hydrogen bond (population of 25%) which is found from the radial distribution function g(r) from both, force field and quantum mechanics/molecular mechanics simulations.

  13. Structure and dynamics of aqueous solution of uranyl ions

    SciTech Connect (OSTI)

    Chopra, Manish; Choudhury, Niharendu

    2014-04-24

    The present work describes a molecular dynamics simulation study of structure and dynamics of aqueous solution of uranyl ions in water. Structural properties of the system in terms of radial distribution functions and dynamical characteristics as obtained through velocity autocorrelation function and mean square displacements have been analyzed. The results for radial distribution functions show the oxygen of water to form the first solvation shell at 2.4 around the uranium atom, whereas the hydrogen atoms of water are distributed around the uranium atom with the major peak at around 3.0 . Analyses of transport behaviors of ions and water through MSD indicates that the diffusion of the uranyl ion is much less as compared to that of the water molecules. It is also observed that the dynamical behavior of water molecules gets modified due to the presence of uranyl ion. The effect of increase in concentration of uranyl ions on the structure and dynamics of water molecules is also studied.

  14. Laser plasma x-ray source for ultrafast time-resolved x-ray absorption spectroscopy

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Miaja-Avila, L.; O'Neil, G. C.; Uhlig, J.; Cromer, C. L.; Dowell, M. L.; Jimenez, R.; Hoover, A. S.; Silverman, K. L.; Ullom, J. N.

    2015-03-02

    We describe a laser-driven x-ray plasma source designed for ultrafast x-ray absorption spectroscopy. The source is comprised of a 1 kHz, 20 W, femtosecond pulsed infrared laser and a water target. We present the x-ray spectra as a function of laser energy and pulse duration. Additionally, we investigate the plasma temperature and photon flux as we vary the laser energy. We obtain a 75 μm FWHM x-ray spot size, containing ~106 photons/s, by focusing the produced x-rays with a polycapillary optic. Since the acquisition of x-ray absorption spectra requires the averaging of measurements from >107 laser pulses, we also presentmore » data on the source stability, including single pulse measurements of the x-ray yield and the x-ray spectral shape. In single pulse measurements, the x-ray flux has a measured standard deviation of 8%, where the laser pointing is the main cause of variability. Further, we show that the variability in x-ray spectral shape from single pulses is low, thus justifying the combining of x-rays obtained from different laser pulses into a single spectrum. Finally, we show a static x-ray absorption spectrum of a ferrioxalate solution as detected by a microcalorimeter array. Altogether, our results demonstrate that this water-jet based plasma source is a suitable candidate for laboratory-based time-resolved x-ray absorption spectroscopy experiments.« less

  15. Ultrafast dark-field surface inspection with hybrid-dispersion laser scanning

    SciTech Connect (OSTI)

    Yazaki, Akio; Kim, Chanju; Chan, Jacky; Mahjoubfar, Ata; Goda, Keisuke; Watanabe, Masahiro; Jalali, Bahram

    2014-06-23

    High-speed surface inspection plays an important role in industrial manufacturing, safety monitoring, and quality control. It is desirable to go beyond the speed limitation of current technologies for reducing manufacturing costs and opening a new window onto a class of applications that require high-throughput sensing. Here, we report a high-speed dark-field surface inspector for detection of micrometer-sized surface defects that can travel at a record high speed as high as a few kilometers per second. This method is based on a modified time-stretch microscope that illuminates temporally and spatially dispersed laser pulses on the surface of a fast-moving object and detects scattered light from defects on the surface with a sensitive photodetector in a dark-field configuration. The inspector's ability to perform ultrafast dark-field surface inspection enables real-time identification of difficult-to-detect features on weakly reflecting surfaces and hence renders the method much more practical than in the previously demonstrated bright-field configuration. Consequently, our inspector provides nearly 1000 times higher scanning speed than conventional inspectors. To show our method's broad utility, we demonstrate real-time inspection of the surface of various objects (a non-reflective black film, transparent flexible film, and reflective hard disk) for detection of 10??m or smaller defects on a moving target at 20?m/s within a scan width of 25?mm at a scan rate of 90.9?MHz. Our method holds promise for improving the cost and performance of organic light-emitting diode displays for next-generation smart phones, lithium-ion batteries for green electronics, and high-efficiency solar cells.

  16. Influence of Domain Wall Pinning on the Dynamic Behavior of Magnetic

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Vortices Influence of Domain Wall Pinning on the Dynamic Behavior of Magnetic Vortices Print Soft magnetic, micron-sized thin-film structures with magnetic vortices are intriguing systems that may one day be used in ultrafast computer memories. In such systems, the otherwise in-plane magnetization turns perpendicular to the plane at the center of the vortex, forming the vortex core. Because such a core has two possible polarizations (up or down) and can be switched between these two states

  17. Influence of Domain Wall Pinning on the Dynamic Behavior of Magnetic

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Vortices Influence of Domain Wall Pinning on the Dynamic Behavior of Magnetic Vortices Print Soft magnetic, micron-sized thin-film structures with magnetic vortices are intriguing systems that may one day be used in ultrafast computer memories. In such systems, the otherwise in-plane magnetization turns perpendicular to the plane at the center of the vortex, forming the vortex core. Because such a core has two possible polarizations (up or down) and can be switched between these two states

  18. Influence of Domain Wall Pinning on the Dynamic Behavior of Magnetic

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Vortices Influence of Domain Wall Pinning on the Dynamic Behavior of Magnetic Vortices Print Soft magnetic, micron-sized thin-film structures with magnetic vortices are intriguing systems that may one day be used in ultrafast computer memories. In such systems, the otherwise in-plane magnetization turns perpendicular to the plane at the center of the vortex, forming the vortex core. Because such a core has two possible polarizations (up or down) and can be switched between these two states

  19. Influence of Domain Wall Pinning on the Dynamic Behavior of Magnetic

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Vortices Influence of Domain Wall Pinning on the Dynamic Behavior of Magnetic Vortices Print Soft magnetic, micron-sized thin-film structures with magnetic vortices are intriguing systems that may one day be used in ultrafast computer memories. In such systems, the otherwise in-plane magnetization turns perpendicular to the plane at the center of the vortex, forming the vortex core. Because such a core has two possible polarizations (up or down) and can be switched between these two states

  20. Influence of Domain Wall Pinning on the Dynamic Behavior of Magnetic

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Vortices Influence of Domain Wall Pinning on the Dynamic Behavior of Magnetic Vortices Print Soft magnetic, micron-sized thin-film structures with magnetic vortices are intriguing systems that may one day be used in ultrafast computer memories. In such systems, the otherwise in-plane magnetization turns perpendicular to the plane at the center of the vortex, forming the vortex core. Because such a core has two possible polarizations (up or down) and can be switched between these two states

  1. Influence of Domain Wall Pinning on the Dynamic Behavior of Magnetic

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Vortices Influence of Domain Wall Pinning on the Dynamic Behavior of Magnetic Vortices Print Soft magnetic, micron-sized thin-film structures with magnetic vortices are intriguing systems that may one day be used in ultrafast computer memories. In such systems, the otherwise in-plane magnetization turns perpendicular to the plane at the center of the vortex, forming the vortex core. Because such a core has two possible polarizations (up or down) and can be switched between these two states

  2. Influence of Domain Wall Pinning on the Dynamic Behavior of Magnetic

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Vortices Influence of Domain Wall Pinning on the Dynamic Behavior of Magnetic Vortices Print Soft magnetic, micron-sized thin-film structures with magnetic vortices are intriguing systems that may one day be used in ultrafast computer memories. In such systems, the otherwise in-plane magnetization turns perpendicular to the plane at the center of the vortex, forming the vortex core. Because such a core has two possible polarizations (up or down) and can be switched between these two states

  3. Ultra-fast Laser Synthesis of Nanopore Arrays in Silicon for Bio-molecule Separation and Detection

    SciTech Connect (OSTI)

    Tringe, J W; Ileri, N; Letant, S E; Stroeve, P; Shirk, M; Zaidi, S; Balhorn, R L; Siders, C W

    2008-02-07

    We demonstrate that interference of ultra-fast pulses of laser light can create regular patterns in thin silicon membranes that are compatible with the formation of a uniform array of nanopores. The spacing and size of these pores can be tuned by changing the laser energy, wavelength and number of ultra-short pulses. Short pulses and wavelengths ({approx}550 nm and smaller) are needed to define controllable nanoscale features in silicon. Energy must be localized in time and space to produce the etching, ablation or amorphization effects over the {approx}100 nm length scales appropriate for definition of single pores. Although in this brief study pattern uniformity was limited by laser beam quality, a complementary demonstration reported here used continuous-wave interferometric laser exposure of photoresist to show the promise of the ultra-fast approach for producing uniform pore arrays. The diameters of these interferometrically-defined features are significantly more uniform than the diameters of pores in state-of-the-art polycarbonate track etch membranes widely used for molecular separations.

  4. Sandia Energy - Scattering Dynamics

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Scattering Dynamics Home Transportation Energy Predictive Simulation of Engines Combustion Chemistry Chemical Dynamics Scattering Dynamics Scattering DynamicsAshley...

  5. Polarizability effects on the structure and dynamics of ionic liquids

    SciTech Connect (OSTI)

    Cavalcante, Ary de Oliveira; Ribeiro, Mauro C. C.; Skaf, Munir S.

    2014-04-14

    Polarization effects on the structure and dynamics of ionic liquids are investigated using molecular dynamics simulations. Four different ionic liquids were simulated, formed by the anions Cl{sup ?} and PF{sub 6}{sup ?}, treated as single fixed charge sites, and the 1-n-alkyl-3-methylimidazolium cations (1-ethyl and 1-butyl-), which are polarizable. The partial charge fluctuation of the cations is provided by the electronegativity equalization model (EEM) and a complete parameter set for the cations electronegativity (?) and hardness (J) is presented. Results obtained from a non-polarizable model for the cations are also reported for comparison. Relative to the fixed charged model, the equilibrium structure of the first solvation shell around the imidazolium cations shows that inclusion of EEM polarization forces brings cations closer to each other and that anions are preferentially distributed above and below the plane of the imidazolium ring. The polarizable model yields faster translational and reorientational dynamics than the fixed charges model in the rotational-diffusion regime. In this sense, the polarizable model dynamics is in better agreement with the experimental data.

  6. Large-Scale First-Principles Molecular Dynamics Simulations with Electrostatic Embedding: Application to Acetylcholinesterase Catalysis

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Fattebert, Jean-Luc; Lau, Edmond Y.; Bennion, Brian J.; Huang, Patrick; Lightstone, Felice C.

    2015-10-22

    Enzymes are complicated solvated systems that typically require many atoms to simulate their function with any degree of accuracy. We have recently developed numerical techniques for large scale First-Principles molecular dynamics simulations and applied them to study the enzymatic reaction catalyzed by acetylcholinesterase. We carried out Density functional theory calculations for a quantum mechanical (QM) sub- system consisting of 612 atoms with an O(N) complexity finite-difference approach. The QM sub-system is embedded inside an external potential field representing the electrostatic effect due to the environment. We obtained finite temperature sampling by First-Principles molecular dynamics for the acylation reaction of acetylcholinemore » catalyzed by acetylcholinesterase. Our calculations shows two energies barriers along the reaction coordinate for the enzyme catalyzed acylation of acetylcholine. In conclusion, the second barrier (8.5 kcal/mole) is rate-limiting for the acylation reaction and in good agreement with experiment.« less

  7. Origin and dynamics of vortex rings in drop splashing

    SciTech Connect (OSTI)

    Lee, Ji San; Park, Su Ji; Lee, Jun Ho; Weon, Byung Mook; Fezzaa, Kamel; Je, Jung Ho

    2015-09-04

    A vortex is a flow phenomenon that is very commonly observed in nature. More than a century, a vortex ring that forms during drop splashing has caught the attention of many scientists due to its importance in understanding fluid mixing and mass transport processes. However, the origin of the vortices and their dynamics remain unclear, mostly due to the lack of appropriate visualization methods. Here, with ultrafast X-ray phase-contrast imaging, we show that the formation of vortex rings originates from the energy transfer by capillary waves generated at the moment of the drop impact. Interestingly, we find a row of vortex rings along the drop wall, as demonstrated by a phase diagram established here, with different power-law dependencies of the angular velocities on the Reynolds number. These results provide important insight that allows understanding and modelling any type of vortex rings in nature, beyond just vortex rings during drop splashing.

  8. Origin and dynamics of vortex rings in drop splashing

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Lee, Ji San; Park, Su Ji; Lee, Jun Ho; Weon, Byung Mook; Fezzaa, Kamel; Je, Jung Ho

    2015-09-04

    A vortex is a flow phenomenon that is very commonly observed in nature. More than a century, a vortex ring that forms during drop splashing has caught the attention of many scientists due to its importance in understanding fluid mixing and mass transport processes. However, the origin of the vortices and their dynamics remain unclear, mostly due to the lack of appropriate visualization methods. Here, with ultrafast X-ray phase-contrast imaging, we show that the formation of vortex rings originates from the energy transfer by capillary waves generated at the moment of the drop impact. Interestingly, we find a row ofmore » vortex rings along the drop wall, as demonstrated by a phase diagram established here, with different power-law dependencies of the angular velocities on the Reynolds number. These results provide important insight that allows understanding and modelling any type of vortex rings in nature, beyond just vortex rings during drop splashing.« less

  9. Ultrafast time-resolved spectroscopy of the light-harvesting complex 2 (LH2) from the photosynthetic bacterium Thermochromatium tepidum

    SciTech Connect (OSTI)

    Niedzwiedzki, Dariusz M.; Fuciman, Marcel; Kobayashi, Masayuki; Frank, Harry A.; Blankenship, Robert E.

    2011-10-08

    The light-harvesting complex 2 from the thermophilic purple bacterium Thermochromatium tepidum was purified and studied by steady-state absorption and fluorescence, sub-nanosecond-time-resolved fluorescence and femtosecond time-resolved transient absorption spectroscopy. The measurements were performed at room temperature and at 10 K. The combination of both ultrafast and steady-state optical spectroscopy methods at ambient and cryogenic temperatures allowed the detailed study of carotenoid (Car)-to-bacteriochlorophyll (BChl) as well BChl-to-BChl excitation energy transfer in the complex. The studies show that the dominant Cars rhodopin (N = 11) and spirilloxanthin (N = 13) do not play a significant role as supportive energy donors for BChl a. This is related with their photophysical properties regulated by long ?-electron conjugation. On the other hand, such properties favor some of the Cars, particularly spirilloxanthin (N = 13) to play the role of the direct quencher of the excited singlet state of BChl.

  10. High quality single shot ultrafast MeV electron diffraction from a photocathode radio-frequency gun

    SciTech Connect (OSTI)

    Fu, Feichao; Liu, Shengguang; Zhu, Pengfei; Xiang, Dao Zhang, Jie; Cao, Jianming

    2014-08-15

    A compact ultrafast electron diffractometer, consisting of an s-band 1.6 cell photocathode radio-frequency gun, a multi-function changeable sample chamber, and a sensitive relativistic electron detector, was built at Shanghai Jiao Tong University. High-quality single-shot transmission electron diffraction patterns have been recorded by scattering 2.5 MeV electrons off single crystalline gold and polycrystalline aluminum samples. The high quality diffraction pattern indicates an excellent spatial resolution, with the ratio of the diffraction ring radius over the ring rms width beyond 10. The electron pulse width is estimated to be about 300 fs. The high temporal and spatial resolution may open new opportunities in various areas of sciences.

  11. Cost effective nanostructured copper substrates prepared with ultrafast laser pulses for explosives detection using surface enhanced Raman scattering

    SciTech Connect (OSTI)

    Hamad, Syed; Podagatlapalli, G. Krishna; Soma, Venugopal Rao E-mail: soma-venu@yahoo.com; Mohiddon, Md. Ahamad

    2014-06-30

    Ultrafast laser pulses induced surface nanostructures were fabricated on a copper (Cu) target through ablation in acetone, dichloromethane, acetonitrile, and chloroform. Surface morphological information accomplished from the field emission scanning electron microscopic data demonstrated the diversities of ablation mechanism in each case. Fabricated Cu substrates were utilized exultantly to investigate the surface plasmon (localized and propagating) mediated enhancements of different analytes using surface enhance Raman scattering (SERS) studies. Multiple utility of these substrates were efficiently demonstrated by collecting the SERS data of Rhodamine 6G molecule and two different secondary explosive molecules such as 5-amino-3-nitro-l,2,4-triazole and trinitrotoluene on different days which were weeks apart. We achieved significant enhancement factors of >10{sup 5} through an easily adoptable cleaning procedure.

  12. System and method for ultrafast optical signal detecting via a synchronously coupled anamorphic light pulse encoded laterally

    DOE Patents [OSTI]

    Heebner, John E. (Livermore, CA)

    2010-08-03

    In one general embodiment, a method for ultrafast optical signal detecting is provided. In operation, a first optical input signal is propagated through a first wave guiding layer of a waveguide. Additionally, a second optical input signal is propagated through a second wave guiding layer of the waveguide. Furthermore, an optical control signal is applied to a top of the waveguide, the optical control signal being oriented diagonally relative to the top of the waveguide such that the application is used to influence at least a portion of the first optical input signal propagating through the first wave guiding layer of the waveguide. In addition, the first and the second optical input signals output from the waveguide are combined. Further, the combined optical signals output from the waveguide are detected. In another general embodiment, a system for ultrafast optical signal recording is provided comprising a waveguide including a plurality of wave guiding layers, an optical control source positioned to propagate an optical control signal towards the waveguide in a diagonal orientation relative to a top of the waveguide, at least one optical input source positioned to input an optical input signal into at least a first and a second wave guiding layer of the waveguide, and a detector for detecting at least one interference pattern output from the waveguide, where at least one of the interference patterns results from a combination of the optical input signals input into the first and the second wave guiding layer. Furthermore, propagation of the optical control signal is used to influence at least a portion of the optical input signal propagating through the first wave guiding layer of the waveguide.

  13. Water exchange dynamics around H?O? and OH? ions

    SciTech Connect (OSTI)

    Roy, Santanu; Dang, Liem X.

    2015-05-01

    Proton transfer in water and other solvents is a complicated process and an active research area. Conformational changes of water hydrating a proton can have a significant influence on proton dynamics. A hydrated proton leads to H?O? that forms three hydrogen bonds with neighboring water molecules. In this letter, we report the first computer simulation of the dynamics of water exchanging between the first and second solvation shells of H?O?. Employing different rate theories for chemical reactions such as the transition state theory, the Grote-Hynes theory, the reactive flux method, and the Impey-Madden-McDonald method, we calculate the solvent exchange rates from molecular dynamics simulations that account for explicit polarization effects. In addition, we also study water exchanges around OH? and find that the corresponding time scale (~50 picoseconds [ps]) is much smaller than that for H?O? (~100 ps). Results from all the rate theories are computed and compared. This work was supported by the US Department of Energy, Office of Science, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences, and Biosciences. The calculations were carried out using computer resources provided by the Office of Basic Energy Sciences.

  14. Towards simultaneous measurements of electronic and structural properties in ultra-fast x-ray free electron laser absorption spectroscopy experiments

    SciTech Connect (OSTI)

    Gaudin, J.; Fourment, C.; Cho, B. I.; Engelhorn, K.; Galtier, E.; Harmand, M.; Leguay, P. M.; Lee, H. J.; Nagler, B.; Nakatsutsumi, M.; Ozkan, C.; Strmer, M.; Toleikis, S.; Tschentscher, Th.; Heimann, P. A.; Dorchies, F.

    2014-04-17

    The rapidly growing ultrafast science with X-ray lasers unveils atomic scale processes with unprecedented time resolution bringing the so called molecular movie within reach. X-ray absorption spectroscopy is one of the most powerful x-ray techniques providing both local atomic order and electronic structure when coupled with ad-hoc theory. Collecting absorption spectra within few x-ray pulses is possible only in a dispersive setup. We demonstrate ultrafast time-resolved measurements of the LIII-edge x-ray absorption near-edge spectra of irreversibly laser excited Molybdenum using an average of only few x-ray pulses with a signal to noise ratio limited only by the saturation level of the detector. The simplicity of the experimental set-up makes this technique versatile and applicable for a wide range of pump-probe experiments, particularly in the case of non-reversible processes.

  15. Towards simultaneous measurements of electronic and structural properties in ultra-fast x-ray free electron laser absorption spectroscopy experiments

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Gaudin, J.; Fourment, C.; Cho, B. I.; Engelhorn, K.; Galtier, E.; Harmand, M.; Leguay, P. M.; Lee, H. J.; Nagler, B.; Nakatsutsumi, M.; et al

    2014-04-17

    The rapidly growing ultrafast science with X-ray lasers unveils atomic scale processes with unprecedented time resolution bringing the so called “molecular movie” within reach. X-ray absorption spectroscopy is one of the most powerful x-ray techniques providing both local atomic order and electronic structure when coupled with ad-hoc theory. Collecting absorption spectra within few x-ray pulses is possible only in a dispersive setup. We demonstrate ultrafast time-resolved measurements of the LIII-edge x-ray absorption near-edge spectra of irreversibly laser excited Molybdenum using an average of only few x-ray pulses with a signal to noise ratio limited only by the saturation level ofmore » the detector. The simplicity of the experimental set-up makes this technique versatile and applicable for a wide range of pump-probe experiments, particularly in the case of non-reversible processes.« less

  16. Ultrafast laser and swift heavy ion irradiation: Response of Gd{sub 2}O{sub 3} and ZrO{sub 2} to intense electronic excitation

    SciTech Connect (OSTI)

    Rittman, Dylan R.; Tracy, Cameron L.; Cusick, Alex B.; Abere, Michael J.; Yalisove, Steven M.; Torralva, Ben; Ewing, Rodney C.

    2015-04-27

    In order to investigate the response of materials to extreme conditions, there are several approaches to depositing extremely high concentrations of energy into very small volumes of material, including ultrafast laser and swift heavy ion (SHI) irradiation. In this study, crystalline-to-crystalline phase transformations in cubic Gd{sub 2}O{sub 3} and monoclinic ZrO{sub 2} have been investigated using ultrafast laser irradiation. The phases produced by the extreme conditions of irradiation were characterized by grazing incidence x-ray diffraction (GIXRD) and Raman spectroscopy. Gd{sub 2}O{sub 3} exhibited a cubic-to-monoclinic phase transformation, as evidenced by the appearance of the monoclinic (402{sup }), (003), (310), and (112{sup }) peaks in the GIXRD pattern and of four A{sub g} and three B{sub g} Raman modes. ZrO{sub 2} underwent a monoclinic-to-tetragonal phase transformation, as evidenced by the emergence of the tetragonal (101) peak in the GIXRD pattern and of E{sub g} and A{sub 1g} Raman modes. The new phases formed by ultrafast laser irradiation are high temperature polymorphs of the two materials. No evidence of amorphization was seen in the GIXRD data, though Raman spectroscopy indicated point defect accumulation. These results are identical to those produced by irradiation with SHIs, which also deposit energy in materials primarily through electronic excitation. The similarity in damage process and material response between ultrafast laser and SHI irradiation suggests a fundamental relationship between these two techniques.

  17. TH-A-18C-04: Ultrafast Cone-Beam CT Scatter Correction with GPU-Based Monte Carlo Simulation

    SciTech Connect (OSTI)

    Xu, Y; Bai, T; Yan, H; Ouyang, L; Wang, J; Pompos, A; Jiang, S; Jia, X; Zhou, L

    2014-06-15

    Purpose: Scatter artifacts severely degrade image quality of cone-beam CT (CBCT). We present an ultrafast scatter correction framework by using GPU-based Monte Carlo (MC) simulation and prior patient CT image, aiming at automatically finish the whole process including both scatter correction and reconstructions within 30 seconds. Methods: The method consists of six steps: 1) FDK reconstruction using raw projection data; 2) Rigid Registration of planning CT to the FDK results; 3) MC scatter calculation at sparse view angles using the planning CT; 4) Interpolation of the calculated scatter signals to other angles; 5) Removal of scatter from the raw projections; 6) FDK reconstruction using the scatter-corrected projections. In addition to using GPU to accelerate MC photon simulations, we also use a small number of photons and a down-sampled CT image in simulation to further reduce computation time. A novel denoising algorithm is used to eliminate MC scatter noise caused by low photon numbers. The method is validated on head-and-neck cases with simulated and clinical data. Results: We have studied impacts of photo histories, volume down sampling factors on the accuracy of scatter estimation. The Fourier analysis was conducted to show that scatter images calculated at 31 angles are sufficient to restore those at all angles with <0.1% error. For the simulated case with a resolution of 512×512×100, we simulated 10M photons per angle. The total computation time is 23.77 seconds on a Nvidia GTX Titan GPU. The scatter-induced shading/cupping artifacts are substantially reduced, and the average HU error of a region-of-interest is reduced from 75.9 to 19.0 HU. Similar results were found for a real patient case. Conclusion: A practical ultrafast MC-based CBCT scatter correction scheme is developed. The whole process of scatter correction and reconstruction is accomplished within 30 seconds. This study is supported in part by NIH (1R01CA154747-01), The Core Technology Research in Strategic Emerging Industry, Guangdong, China (2011A081402003)

  18. Ultrafast pulse amplification in mode-locked vertical external-cavity surface-emitting lasers

    SciTech Connect (OSTI)

    Bttge, C. N. Hader, J.; Kilen, I.; Moloney, J. V.; Koch, S. W.

    2014-12-29

    A fully microscopic many-body Maxwellsemiconductor Bloch model is used to investigate the influence of the non-equilibrium carrier dynamics on the short-pulse amplification in mode-locked semiconductor microlaser systems. The numerical solution of the coupled equations allows for a self-consistent investigation of the lightmatter coupling dynamics, the carrier kinetics in the saturable absorber and the multiple-quantum-well gain medium, as well as the modification of the light field through the pulse-induced optical polarization. The influence of the pulse-induced non-equilibrium modifications of the carrier distributions in the gain medium and the saturable absorber on the single-pulse amplification in the laser cavity is identified. It is shown that for the same structure, quantum wells, and gain bandwidth the non-equilibrium carrier dynamics lead to two preferred operation regimes: one with pulses in the (sub-)100 fs-regime and one with multi-picosecond pulses. The recovery time of the saturable absorber determines in which regime the device operates.

  19. Dynamics of soft Nanomaterials captured by transmission electron microscopy in liquid water

    SciTech Connect (OSTI)

    Proetto, Maria T.; Rush, Anthony M.; Chien, Miao-Ping; Abellan Baeza, Patricia; Patterson, Joseph P.; Thompson, Matthew P.; Olson, Norman H.; Moore, Curtis E.; Rheingold, Arnold L.; Andolina, Christopher; Millstone, Jill; Howell, Stephen B.; Browning, Nigel D.; Evans, James E.; Gianneschi, Nathan C.

    2014-01-14

    In this paper we present in situ transmission electron microscopy (TEM) of soft, synthetic nanoparticles with a comparative analysis using conventional TEM methods. This comparison is made with the simple aim of describing what is an unprecedented example of in situ imaging by TEM. However, we contend the technique will quickly become essential in the characterization of analogous systems, especially where dynamics are of interest in the solvated state. In this case, particles were studied which were obtained from the direct polymerization of an oxaliplatin analog, designed for an ongoing program in novel chemotherapeutic delivery systems. The resulting nanoparticles provided sufficient contrast for facile imaging in situ, and point toward key design parameters that enable this new characterization approach for organic nanomaterials. We describe the preparation of the synthetic micellar nanoparticles to- gether with their characterization in liquid water.

  20. Ultrafast electrochemical preparation of graphene/CoS nanosheet counter electrodes for efficient dye-sensitized solar cells

    SciTech Connect (OSTI)

    Zhu, Chongyang; Zhu, Yimei; Min, Huihua; Xu, Feng; Chen, Jing; Dong, Hui; Tong, Ling; Sun, Litao

    2015-10-05

    Utilizing inexpensive, high-efficiency counter electrodes (CEs) to replace the traditional platinum counterparts in dye-sensitized solar cells (DSSCs) is worthwhile. In this paper, we detail how we synchronously prepared composite CEs of CoS nanosheet arrays and reduced graphene oxide (rGO) layers for the first time via a low temperature, ultrafast one-step electrochemical strategy. With this approach, the whole fabrication process of the composite CEs was only a small percentage of the average time (~15 hours) using other methods. The DSSC assembled with the rGO–CoS composite CE achieved an enhanced power conversion efficiency (PCE) of 8.34%, which is dramatically higher than 6.27% of pure CoS CE-based DSSC and even exceeds 7.50% of Pt CE-based DSSC. The outstanding PCE breakthrough is undoubtedly attributed to the enhancement in electrocatalytic ability of the rGO–CoS composite CE due to the incorporation of highly conducting rGO layers and the GO layers-induced growth of CoS nanosheet arrays with higher density and larger surface area. Therefore, lower charge-transfer resistance and higher exchange current density can be achieved as corroborated by the electrochemical impedance spectra (EIS) and Tafel polarization curves (TPCs). As a result, further experiments also proved that the electrochemical strategy exhibited its universality of fabricating other graphene-enhanced chalcogenide functional composite films.

  1. Ultrafast electrochemical preparation of graphene/CoS nanosheet counter electrodes for efficient dye-sensitized solar cells

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Zhu, Chongyang; Zhu, Yimei; Min, Huihua; Xu, Feng; Chen, Jing; Dong, Hui; Tong, Ling; Sun, Litao

    2015-10-05

    Utilizing inexpensive, high-efficiency counter electrodes (CEs) to replace the traditional platinum counterparts in dye-sensitized solar cells (DSSCs) is worthwhile. In this paper, we detail how we synchronously prepared composite CEs of CoS nanosheet arrays and reduced graphene oxide (rGO) layers for the first time via a low temperature, ultrafast one-step electrochemical strategy. With this approach, the whole fabrication process of the composite CEs was only a small percentage of the average time (~15 hours) using other methods. The DSSC assembled with the rGO–CoS composite CE achieved an enhanced power conversion efficiency (PCE) of 8.34%, which is dramatically higher than 6.27%more » of pure CoS CE-based DSSC and even exceeds 7.50% of Pt CE-based DSSC. The outstanding PCE breakthrough is undoubtedly attributed to the enhancement in electrocatalytic ability of the rGO–CoS composite CE due to the incorporation of highly conducting rGO layers and the GO layers-induced growth of CoS nanosheet arrays with higher density and larger surface area. Therefore, lower charge-transfer resistance and higher exchange current density can be achieved as corroborated by the electrochemical impedance spectra (EIS) and Tafel polarization curves (TPCs). As a result, further experiments also proved that the electrochemical strategy exhibited its universality of fabricating other graphene-enhanced chalcogenide functional composite films.« less

  2. NuSTAR REVEALS RELATIVISTIC REFLECTION BUT NO ULTRA-FAST OUTFLOW IN THE QUASAR PG 1211+143

    SciTech Connect (OSTI)

    Zoghbi, A.; Miller, J. M.; Walton, D. J.; Stern, D.; Harrison, F. A.; Fabian, A. C.; Reynolds, C. S.; Boggs, S. E.; Craig, W.; Christensen, F. E.; Hailey, C. J.; Zhang, W. W.

    2015-02-01

    We report on four epochs of observations of the quasar PG 1211+143 using NuSTAR. The net exposure time is 300 ks. Prior work on this source found suggestive evidence of an ultra-fast outflow (UFO) in the Fe K band with a velocity of approximately 0.1c. The putative flow would carry away a high-mass flux and kinetic power, with broad implications for feedback and black hole--galaxy co-evolution. NuSTAR detects PG 1211+143 out to 30 keV, meaning that the continuum is well-defined both through and above the Fe K band. A characteristic relativistic disk reflection spectrum is clearly revealed via a broad Fe K emission line and Compton back-scattering curvature. The data offer only weak constraints on the spin of the black hole. A careful search for UFOs shows no significant absorption feature above 90% confidence. The limits are particularly tight when relativistic reflection is included. We discuss the statistics and the implications of these results in terms of connections between accretion onto quasars, Seyferts, and stellar-mass black holes, and feedback into their host environments.

  3. Study of beam loading and its compensation in the Compact Ultrafast Terahertz Free-Electron Laser injector linac

    SciTech Connect (OSTI)

    Lal, Shankar Pant, K. K.

    2014-12-15

    The RF properties of an accelerating structure, and the pulse structure and charge per bunch in the electron beam propagating through it are important parameters that determine the impact of beam loading in the structure. The injector linac of the Compact Ultrafast Terahertz Free-Electron Laser (CUTE-FEL) has been operated with two different pulse structures during initial commissioning experiments and the effect of beam loading on the accelerated electron beam parameters has been studied analytically for these two pulse structures. This paper discusses the analytical study of beam loading in a Standing Wave, Plane Wave Transformer linac employed in the CUTE-FEL setup, and a possible technique for its compensation for the electron beam parameters of the CUTE-FEL. A parametric study has been performed to study beam loading for different beam currents and to optimize injection time of the electron beam to compensate beam loading. Results from the parametric study have also been used to explain previously observed results from acceleration experiments in the CUTE-FEL setup.

  4. Optimization of chemical compositions in low-carbon Al-killed enamel steel produced by ultra-fast continuous annealing

    SciTech Connect (OSTI)

    Dong, Futao; Du, Linxiu; Liu, Xianghua; Xue, Fei

    2013-10-15

    The influence of Mn,S and B contents on microstructural characteristics, mechanical properties and hydrogen trapping ability of low-carbon Al-killed enamel steel was investigated. The materials were produced and processed in a laboratory and the ultra-fast continuous annealing processing was performed using a continuous annealing simulator. It was found that increasing Mn,S contents in steel can improve its hydrogen trapping ability which is attributed by refined ferrite grains, more dispersed cementite and added MnS inclusions. Nevertheless, it deteriorates mechanical properties of steel sheet. Addition of trace boron results in both good mechanical properties and significantly improved hydrogen trapping ability. The boron combined with nitrogen segregating at grain boundaries, cementite and MnS inclusions, provides higher amount of attractive hydrogen trapping sites and raises the activation energy for hydrogen desorption from them. - Highlights: We study microstructures and properties in low-carbon Al-killed enamel steel. Hydrogen diffusion coefficients are measured to reflect fish-scale resistance. Manganese improves hydrogen trapping ability but decrease deep-drawing ability. Boron improves both hydrogen trapping ability and deep-drawing ability. Both excellent mechanical properties and fish-scale resistance can be matched.

  5. Photodissociation Dynamics

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Photodissociation Dynamics - Sandia Energy Energy Search Icon Sandia Home Locations Contact Us Employee Locator Energy & Climate Secure & Sustainable Energy Future Stationary Power Energy Conversion Efficiency Solar Energy Wind Energy Water Power Supercritical CO2 Geothermal Natural Gas Safety, Security & Resilience of the Energy Infrastructure Energy Storage Nuclear Power & Engineering Grid Modernization Battery Testing Nuclear Fuel Cycle Defense Waste Management Programs

  6. Scattering Dynamics

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Scattering Dynamics - Sandia Energy Energy Search Icon Sandia Home Locations Contact Us Employee Locator Energy & Climate Secure & Sustainable Energy Future Stationary Power Energy Conversion Efficiency Solar Energy Wind Energy Water Power Supercritical CO2 Geothermal Natural Gas Safety, Security & Resilience of the Energy Infrastructure Energy Storage Nuclear Power & Engineering Grid Modernization Battery Testing Nuclear Fuel Cycle Defense Waste Management Programs Advanced

  7. Chemical Dynamics

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Dynamics - Sandia Energy Energy Search Icon Sandia Home Locations Contact Us Employee Locator Energy & Climate Secure & Sustainable Energy Future Stationary Power Energy Conversion Efficiency Solar Energy Wind Energy Water Power Supercritical CO2 Geothermal Natural Gas Safety, Security & Resilience of the Energy Infrastructure Energy Storage Nuclear Power & Engineering Grid Modernization Battery Testing Nuclear Fuel Cycle Defense Waste Management Programs Advanced Nuclear Energy

  8. DISCOVERY OF ULTRA-FAST OUTFLOWS IN A SAMPLE OF BROAD-LINE RADIO GALAXIES OBSERVED WITH SUZAKU

    SciTech Connect (OSTI)

    Tombesi, F.; Sambruna, R. M.; Mushotzky, R. F.; Braito, V.; Ballo, L.; Cappi, M.

    2010-08-10

    We present the results of a uniform and systematic search for blueshifted Fe K absorption lines in the X-ray spectra of five bright broad-line radio galaxies observed with Suzaku. We detect, for the first time in radio-loud active galactic nuclei (AGNs) at X-rays, several absorption lines at energies greater than 7 keV in three out of five sources, namely, 3C 111, 3C 120, and 3C 390.3. The lines are detected with high significance according to both the F-test and extensive Monte Carlo simulations. Their likely interpretation as blueshifted Fe XXV and Fe XXVI K-shell resonance lines implies an origin from highly ionized gas outflowing with mildly relativistic velocities, in the range v {approx_equal} 0.04-0.15c. A fit with specific photoionization models gives ionization parameters in the range log {xi} {approx_equal} 4-5.6 erg s{sup -1} cm and column densities of N {sub H} {approx_equal} 10{sup 22}-10{sup 23} cm{sup -2}. These characteristics are very similar to those of the ultra-fast outflows (UFOs) previously observed in radio-quiet AGNs. Their estimated location within {approx}0.01-0.3 pc of the central super-massive black hole suggests a likely origin related with accretion disk winds/outflows. Depending on the absorber covering fraction, the mass outflow rate of these UFOs can be comparable to the accretion rate and their kinetic power can correspond to a significant fraction of the bolometric luminosity and is comparable to their typical jet power. Therefore, these UFOs can play a significant role in the expected feedback from the AGN to the surrounding environment and can give us further clues on the relation between the accretion disk and the formation of winds/jets in both radio-quiet and radio-loud AGNs.

  9. Research | Argonne National Laboratory

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    and Ultrafast Imaging Integrating ultrafast time-resolved imaging with large-scale molecular dynamics modeling and in situ data analysis and visualization in order to...

  10. Effect of focal geometry on radiation from atomic ionization in an ultrastrong and ultrafast laser field

    SciTech Connect (OSTI)

    Ghebregziabher, Isaac; Walker, Barry C.

    2007-08-15

    We use a tunneling-Monte Carlo model to calculate the dynamics and emitted Larmor radiation from electrons ionized in an ultrashort and ultrastrong pulsed laser focus over the intensity range from 10{sup 17} to 10{sup 20} W/cm{sup 2}. We find the spatial variation of a laser field affects the radiation and can no longer be neglected at laser intensities leading to relativistic effects. We identify three regimes for the interaction as a function of the ratio of the single cycle quiver amplitude of the photoelectron to the laser focus waist. Adopting a one-dimensional or plane wave approximation when the laser driven excursion of the photoelectron exceeds the focus waist overestimates the total radiated energy by as much as an order of magnitude. Despite this, the spectral amplitude of the highest-energy photons from ionization in a laser focus is comparable to the plane wave case for excursions up to the beam waist since the laser focus imparts an extra boost of speed for electrons exiting the focus. Full spatial and temporal integration that includes the ionization of charge states before the peak of the pulse do not differ significantly from results that include only the radiation from ionization of the charge state at the peak of the laser field.

  11. Linewidth of the harmonics in a microwave frequency comb generated by focusing a mode-locked ultrafast laser on a tunneling junction

    SciTech Connect (OSTI)

    Hagmann, Mark J.; Stenger, Frank S.; Yarotski, Dmitry A.

    2013-12-14

    Previous analyses suggest that microwave frequency combs (MFCs) with harmonics having extremely narrow linewidths could be produced by photodetection with a mode-locked ultrafast laser. In the MFC generated by focusing a passively mode-locked ultrafast laser on a tunneling junction, 200 harmonics from 74.254 MHz to 14.85 GHz have reproducible measured linewidths approximating the 1 Hz resolution bandwidth (RBW) of the spectrum analyzer. However, in new measurements at a RBW of 0.1 Hz, the linewidths are distributed from 0.12 to 1.17 Hz. Measurements and analysis suggest that, because the laser is not stabilized, the stochastic drift in the pulse repetition rate is the cause for the distribution in measured linewidths. It appears that there are three cases in which the RBW is (1) greater than, (2) less than, or (3) comparable with the intrinsic linewidth. The measured spectra in the third class are stochastic and may show two or more peaks at a single harmonic.

  12. Visualizing the non-equilibrium dynamics of photoinduced intramolecular electron transfer with femtosecond X-ray pulses

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Canton, Sophie E.; Kjær, Kasper S.; Vankó, György; van Driel, Tim B.; Adachi, Shin -ichi; Bordage, Amélie; Bressler, Christian; Chabera, Pavel; Christensen, Morten; Dohn, Asmus O.; et al

    2015-03-02

    Ultrafast photoinduced electron transfer preceding energy equilibration still poses many experimental and conceptual challenges to the optimization of photoconversion since an atomic-scale description has so far been beyond reach. Here we combine femtosecond transient optical absorption spectroscopy with ultrafast X-ray emission spectroscopy and diffuse X-ray scattering at the SACLA facility to track the non-equilibrated electronic and structural dynamics within a bimetallic donor–acceptor complex that contains an optically dark centre. Exploiting the 100-fold increase in temporal resolution as compared with storage ring facilities, these measurements constitute the first X-ray-based visualization of a non-equilibrated intramolecular electron transfer process over large interatomic distances.more » Thus experimental and theoretical results establish that mediation through electronically excited molecular states is a key mechanistic feature. The present study demonstrates the extensive potential of femtosecond X-ray techniques as diagnostics of non-adiabatic electron transfer processes in synthetic and biological systems, and some directions for future studies, are outlined.« less

  13. Visualizing the non-equilibrium dynamics of photoinduced intramolecular electron transfer with femtosecond X-ray pulses

    SciTech Connect (OSTI)

    Canton, Sophie E.; Kjr, Kasper S.; Vank, Gyrgy; van Driel, Tim B.; Adachi, Shin -ichi; Bordage, Amlie; Bressler, Christian; Chabera, Pavel; Christensen, Morten; Dohn, Asmus O.; Galler, Andreas; Gawelda, Wojciech; Gosztola, David; Haldrup, Kristoffer; Harlang, Tobias; Liu, Yizhu; Mller, Klaus B.; Nmeth, Zoltn; Nozawa, Shunsuke; Ppai, Mtys; Sato, Tokushi; Sato, Takahiro; Suarez-Alcantara, Karina; Togashi, Tadashi; Tono, Kensuke; Uhlig, Jens; Vithanage, Dimali A.; Wrnmark, Kenneth; Yabashi, Makina; Zhang, Jianxin; Sundstrm, Villy; Nielsen, Martin M.

    2015-03-02

    Ultrafast photoinduced electron transfer preceding energy equilibration still poses many experimental and conceptual challenges to the optimization of photoconversion since an atomic-scale description has so far been beyond reach. Here we combine femtosecond transient optical absorption spectroscopy with ultrafast X-ray emission spectroscopy and diffuse X-ray scattering at the SACLA facility to track the non-equilibrated electronic and structural dynamics within a bimetallic donoracceptor complex that contains an optically dark centre. Exploiting the 100-fold increase in temporal resolution as compared with storage ring facilities, these measurements constitute the first X-ray-based visualization of a non-equilibrated intramolecular electron transfer process over large interatomic distances. Thus experimental and theoretical results establish that mediation through electronically excited molecular states is a key mechanistic feature. The present study demonstrates the extensive potential of femtosecond X-ray techniques as diagnostics of non-adiabatic electron transfer processes in synthetic and biological systems, and some directions for future studies, are outlined.

  14. Ultrafast optical pump-probe spectroscopy is used to reveal the coexistence of coupled antiferromagnetic (AFM)/ferroelectric (FE) and ferromagnetic (FM) orders in multiferroic TbMnO3 films, which can guide researchers in creating new kinds of multiferroic materials.

    SciTech Connect (OSTI)

    Qi, Jingbo; Zhu, Jianxin; Trugman, Stuart A.; Taylor, Antoinette; Jia, Quanxi; Prasankumar, Rohit

    2012-07-06

    Multiferroic materials have attracted much interest in the past decade, due not only to their novel device applications, but also their manifestations of coupling and interactions between different order parameters (particularly electric polarization and magnetic order). Recently, much attention has been focused on perovskite manganites, RMnO{sub 3} (R = rare earth ions), due to the discovery of a large magnetoelectric effect in these materials. The first member of this family to be discovered was TbMnO{sub 3} (TMO), which is now well established as a typical magnetoelectric multiferroic. Extensive experimental and theoretical studies have already been done on single crystal TMO (SC-TMO). In brief, SC-TMO, with a distorted orthorhombic perovskite structure, has an antiferromagnetic (AFM) phase transition at T{sub N} {approx}40 K with sinusoidally ordered Mn moments. Below T{sub FE} {approx} 28 K, ferroelectric (FE) order develops owing to the appearance of cycloidal spiral spin structure. In contrast, there are relatively few reports describing the properties of TMO thin films (typically grown on SrTiO{sub 3} (STO) substrates). In general, thin films can enable new functionality in materials, as their physical parameters can be changed by modifying their structure via strain imposed by the substrate. Strain in particular has the potential to directly couple FE and FM orders, which is very rare. This could benefit electronic device applications by providing low power consumption, high speed operation, and greater electric/magnetic field controllability. Previous investigations of magnetic properties in TMO films revealed an unexpected ferromagnetic (FM) order, in contrast to SC-TMO. However, several important questions regarding these films are still unanswered for instance: (1) What mechanism induces FM order? (2) Can FM, sinusoidal AFM and spiral AFM (or FE) orders coexist? (3) Can FM order be coupled to FE order? To fully understand these unique materials, experimental techniques capable of dynamically unraveling the interplay between these degrees of freedom on an ultrafast timescale are needed. Here, we use ultrafast optical pump-probe spectroscopy to reveal coexisting coupled magnetic orders in epitaxial TMO thin films grown on (001)-STO, which were not observed in previous work. Our temperature (T)-dependent transient differential reflectivity ({Delta}R/R) measurements show clear signatures of sinusoidal AFM, spiral AFM (FE) and FM phases developing as the film thickness changes. We carry out first-principle density functional theory (DFT) calculations to explain the coupling between AFM/FE and FM orders. These results reveal that the coupling between different magnetic orders observed in our multiferroic TMO thin films may offer greater control of functionality as compared to bulk single crystal multiferroics.

  15. Nonadiabatic ab initio molecular dynamics of photoisomerization in bridged azobenzene

    SciTech Connect (OSTI)

    Gao Aihua; Li Bin; Zhang Peiyu; Han Keli [State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023 (China)

    2012-11-28

    The photoisomerization mechanisms of bridged azobenzene are investigated by means of surface hopping dynamics simulations based on the Zhu-Nakamura theory. In the geometry optimizations and potential energy surface calculations, four minimum-energy conical intersections between the ground state and the lowest excited state are found to play important roles in the trans-cis and cis-trans isomerization processes. The trans-cis photoisomerization proceeds through two minimum-energy conical intersections. Ultrafast pedal motion of the N atoms and twisting of phenyl rings around their N-C bonds allows the molecule to move to a minimum-energy conical intersection, after which surface hopping from S{sub 1} to S{sub 0} occurs. In the S{sub 0} state, further rotation occurs around the N=N bond and two N-C bonds until the azo moiety and phenyl rings complete their isomerization. Finally, the cis form is achieved by subsequent adjustment of the ethylene bridge. In the cis-trans photodynamics, there is one rotational pathway, in the middle of which two CIs are responsible for the surface hopping to the S{sub 0} state. After the nonadiabatic transition, the molecule reaches the trans form through a barrierless pathway and the two phenyl rings and the additional bridge complete their reorientation almost at the same time.

  16. Sandia Energy - Chemical Dynamics

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Chemical Dynamics Home Transportation Energy Predictive Simulation of Engines Combustion Chemistry Chemical Dynamics Chemical DynamicsAshley Otero2015-10-28T02:45:37+00:00...

  17. High efficiency, high quality x-ray optic based on ellipsoidally bent highly oriented pyrolytic graphite crystal for ultrafast x-ray diffraction experiments

    SciTech Connect (OSTI)

    Uschmann, I.; Nothelle, U.; Foerster, E.; Arkadiev, V.; Langhoff, N.; Antonov, A.; Grigorieva, I.; Steinkopf, R.; Gebhardt, A

    2005-08-20

    By the use of a thin highly oriented pyrolytic graphite crystal (HOPG) bent to a high-performance ellipsoidal shape it was possible to focus monochromatic x-rays of 4.5 keV photon energy with an efficiency of 0.0033, which is 30 times larger than for previously used bent crystals. Isotropic TiK{sub a}lpha radiation of a 150 {mu}m source was focused onto a 450 {mu}m spot. The size of the focal spot can be explained by broadening due to the mosaic crystal rocking curve. The rocking curve width (FWHM) of the thin graphite foil was determined to 0.11 deg. . The estimated temporal broadening of an ultrashort Kalpha pulse by the crystal is not larger than 300 fs. These properties make the x-ray optic very attractive for ultrafast time-resolved x-ray measurements.

  18. Role of nuclear dynamics in the Asymmetric molecular-frame photoelectron angular distributions for C 1s photoejection from CO{sub 2}

    SciTech Connect (OSTI)

    Miyabe, Shungo; Haxton, Dan; Rescigno, Tom; McCurdy, Bill

    2010-11-30

    We report the results of semiclassical calculations of the asymmetric molecular-frame photoelectron angular distributions for C 1s ionization of CO{sub 2} measured with respect to the CO{sup +} and O{sup +} ions produced by subsequent Auger decay, and show how the decay event can be used to probe ultrafast molecular dynamics of the transient cation. The fixed-nuclei photoionization amplitudes were constructed using variationally obtained electron-molecular ion scattering wave functions. The amplitudes are then used in a semiclassical manner to investigate their dependence on the nuclear dynamics of the cation. The method introduced here can be used to study other core-level ionization events.

  19. Ultrafast neutron detector

    DOE Patents [OSTI]

    Wang, Ching L. (Livermore, CA)

    1987-01-01

    The invention comprises a neutron detector (50) of very high temporal resolution that is particularly well suited for measuring the fusion reaction neutrons produced by laser-driven inertial confinement fusion targets. The detector comprises a biased two-conductor traveling-wave transmission line (54, 56, 58, 68) having a uranium cathode (60) and a phosphor anode (62) as respective parts of the two conductors. A charge line and Auston switch assembly (70, 72, 74) launch an electric field pulse along the transmission line. Neutrons striking the uranium cathode at a location where the field pulse is passing, are enabled to strike the phosphor anode and produce light that is recorded on photographic film (64). The transmission line may be variously configured to achieve specific experimental goals.

  20. Ultrafast neutron detector

    DOE Patents [OSTI]

    Wang, C.L.

    1985-06-19

    A neutron detector of very high temporal resolution is described. It may be used to measure distributions of neutrons produced by fusion reactions that persist for times as short as about 50 picoseconds.

  1. Energetics and dynamics of solvent reorganization in charge-transfer excited states

    SciTech Connect (OSTI)

    Kozik, M.; Sutin, N.; Winkler, J.R.

    1989-01-01

    The dynamics of solvation of the Ru(bpy){sub 2}(CN){sub 2} metal-to-ligand charge-transfer excited state have been examined in a series of aliphatic alcohols. Steady-state emission spectra recorded at low temperature ({approx} 10 K) and at room temperature were used to resolve internal-mode and solvent contributions to the emission bandshape. Time-resolved emission spectra were fit to a model that takes into account internal-mode distortions as well as time-dependent broadening and shifts in emission maxima. A single- exponential solvent relaxation function does not adequately describe the temporal development of the emission profile of Ru(bpy){sub 2}(CN){sub 2} in alcohols. The evolution of the emission spectrum is clearly biphasic, and can be reasonably fit with a biexponential function. The slower of the two relaxation times is comparable to the longest longitudinal relaxation time reported for the bulk solvent. These slower components, however, represent less than half of the overall approach to equilibrium. Local heating due to above-threshold excitation, and local solvent relaxation are two likely sources of the faster dynamics. 25 refs., 3 figs., 2 tabs.

  2. Non-linear optical studies of adsorbates: Spectroscopy and dynamics

    SciTech Connect (OSTI)

    Zhu, Xiangdong.

    1989-08-01

    In the first part of this thesis, we have established a systematic procedure to apply the surface optical second-harmonic generation (SHG) technique to study surface dynamics of adsorbates. In particular, we have developed a novel technique for studies of molecular surface diffusions. In this technique, the laser-induced desorption with two interfering laser beams is used to produce a monolayer grating of adsorbates. The monolayer grating is detected with diffractions of optical SHG. By monitoring the first-order second-harmonic diffraction, we can follow the time evolution of the grating modulation from which we are able to deduce the diffusion constant of the adsorbates on the surface. We have successfully applied this technique to investigate the surface diffusion of CO on Ni(111). The unique advantages of this novel technique will enable us to readily study anisotropy of a surface diffusion with variable grating orientation, and to investigate diffusion processes of a large dynamic range with variable grating spacings. In the second part of this work, we demonstrate that optical infrared-visible sum-frequency generation (SFG) from surfaces can be used as a viable surface vibrational spectroscopic technique. We have successfully recorded the first vibrational spectrum of a monolayer of adsorbates using optical infrared-visible SFG. The qualitative and quantitative correlation of optical SFG with infrared absorption and Raman scattering spectroscopies are examined and experimentally demonstrated. We have further investigated the possibility to use transient infrared-visible SFG to probe vibrational transients and ultrafast relaxations on surfaces. 146 refs.

  3. Shared and Dynamic Libraries

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    flag instructs the compiler wrappers (i.e., ftn, cc, CC) to prepare a dynamically linked executable. edison01% ftn -dynamic -o dynexample.x dynexample.f90 There used to be...

  4. Shared and Dynamic Libraries

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Shared and Dynamic Libraries Shared and Dynamic Libraries The Hopper system can support applications that use dynamic shared libraries (DSL) on the compute nodes. Some "out-of-the-box" applications require DSLs and some popular applications like Python use DSLs as well. Using System Shared and Dynamic Libraries "System" DSLs include those that support software packages found in "typical" Linux distributions, e.g. Python and Perl. To build an application that will

  5. 2012 ATOMIC AND MOLECULAR INTERACTIONS GORDON RESEARCH CONFERENCE AND GORDON RESEARCH SEMINAR, JULY 15-20, 2012

    SciTech Connect (OSTI)

    Zwier, Timothy

    2012-07-20

    At the 2012 Atomic and Molecular Interactions Gordon Conference, there will be talks in several broadly defined and partially overlapping areas: ? Intramolecular and single-collision reaction dynamics; ? Photophysics and photochemistry of excited states; ? Clusters, aerosols and solvation; ? Interactions at interfaces; ? Conformations and folding of large molecules; ? Interactions under extreme conditions of temperature and pressure. The theme of the Gordon Research Seminar on Atomic & Molecular Interactions, in keeping with the tradition of the Atomic and Molecular Interactions Gordon Research Conference, is far-reaching and involves fundamental research in the gas and condensed phases along with application of these ideas to practical chemical fields. The oral presentations, which will contain a combination of both experiment and theory, will focus on four broad categories: ? Ultrafast Phenomena; ? Excited States, Photoelectrons, and Photoions; ? Chemical Reaction Dynamics; ? Biomolecules and Clusters.

  6. Structure, dynamics and stability of water/scCO2/mineral interfaces from ab initio molecular dynamics simulations

    SciTech Connect (OSTI)

    Lee, Mal Soon; McGrail, B. Peter; Rousseau, Roger J.; Glezakou, Vassiliki Alexandra

    2015-10-12

    The interface between a solid and a complex multi-component liquid forms a unique reaction environment whose structure and composition can significantly deviate from either bulk or liquid phase and is poorly understood due the innate difficulty to obtain molecular level information. Feldspar minerals, as typified by the Ca-end member Anorthite, serve as prototypical model systems to assess the reactivity and ion mobility at solid/water-bearing supercritical fluid (WBSF) interfaces due to recent X-ray based measurements that provide information on water-film formation, and cation vacancies at these surfaces. Using density functional theory based molecular dynamics, which allows the evaluation of reactivity and condensed phase dynamics on equal footing, we report on the structure and dynamics of water nucleation and surface aggregation, carbonation and Ca mobilization under geologic carbon sequestration scenarios (T=323 K and P=90 bar). We find that water has a strong enthalpic preference for aggregation on a Ca-rich, O-terminated anorthite (001) surface, but entropy strongly hinders the film formation at very low water concentrations. Carbonation reactions readily occur at electron-rich terminal Oxygen sites adjacent to cation vacancies, when in contact with supercritical CO2. Cation vacancies of this type can form readily in the presence of a water layer that allows for facile and enthalpicly favorable Ca2+ extraction and solvation. Apart from providing unprecedented molecular level detail of a complex three component (mineral, water and scCO2) system), this work highlights the ability of modern capabilities of AIMD methods to begin to qualitatively and quantitatively address structure and reactivity at solid-liquid interfaces of high chemical complexity. This work was supported by the US Department of Energy, Office of Fossil Energy (M.-S. L., B. P. M. and V.-A. G.) and the Office of Basic Energy Science, Division of Chemical Sciences, Geosciences and Biosciences (R.R.), and performed at the Pacific Northwest National Laboratory (PNNL). PNNL is a multi-program national laboratory operated for DOE by Battelle. Computational resources were provided by PNNLs Platform for Institutional Computing (PIC), the W. R. Wiley Environmental Molecular Science Laboratory (EMSL), a national scientific user facility sponsored by the Department of Energys Office of Biological and Environmental Research located at PNNL and the National Energy Research Scientific Computing Center (NERSC) at Lawrence Berkeley National Laboratory.

  7. Hybrid DFT Functional-Based Static and Molecular Dynamics Studies of Excess Electron in Liquid Ethylene Carbonate

    SciTech Connect (OSTI)

    Yu, J. M.; Balbuena, P. B.; Budzien, J. L.; Leung, Kevin

    2011-02-22

    We applied static and dynamic hybrid functional density functional theory (DFT) calculations to study the interactions of one and two excess electrons with ethylene carbonate (EC) liquid and clusters. Optimal structures of (EC)n and (EC)n- clusters devoid of Li+ ions, n = 16, were obtained. The excess electron was found to be localized on a single EC in all cases, and the EC dimeric radical anion exhibits a reduced barrier associated with the breaking of the ethylene carbonoxygen covalent bond compared to EC-. In ab initio molecular dynamics (AIMD) simulations of EC- solvated in liquid EC, large fluctuations in the carbonyl carbonoxygen bond lengths were observed. AIMD simulations of a two-electron attack on EC in EC liquid and on Li metal surfaces yielded products similar to those predicted using nonhybrid DFT functionals, except that CO release did not occur for all attempted initial configurations in the liquid state.

  8. Dynamical principles in neuroscience

    SciTech Connect (OSTI)

    Rabinovich, Mikhail I.; Varona, Pablo; Selverston, Allen I.; Abarbanel, Henry D. I.

    2006-10-15

    Dynamical modeling of neural systems and brain functions has a history of success over the last half century. This includes, for example, the explanation and prediction of some features of neural rhythmic behaviors. Many interesting dynamical models of learning and memory based on physiological experiments have been suggested over the last two decades. Dynamical models even of consciousness now exist. Usually these models and results are based on traditional approaches and paradigms of nonlinear dynamics including dynamical chaos. Neural systems are, however, an unusual subject for nonlinear dynamics for several reasons: (i) Even the simplest neural network, with only a few neurons and synaptic connections, has an enormous number of variables and control parameters. These make neural systems adaptive and flexible, and are critical to their biological function. (ii) In contrast to traditional physical systems described by well-known basic principles, first principles governing the dynamics of neural systems are unknown. (iii) Many different neural systems exhibit similar dynamics despite having different architectures and different levels of complexity. (iv) The network architecture and connection strengths are usually not known in detail and therefore the dynamical analysis must, in some sense, be probabilistic. (v) Since nervous systems are able to organize behavior based on sensory inputs, the dynamical modeling of these systems has to explain the transformation of temporal information into combinatorial or combinatorial-temporal codes, and vice versa, for memory and recognition. In this review these problems are discussed in the context of addressing the stimulating questions: What can neuroscience learn from nonlinear dynamics, and what can nonlinear dynamics learn from neuroscience?.

  9. Protein Dynamics and Biocatalysis

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Protein Dynamics and Biocatalysis Protein Dynamics and Biocatalysis 1998 Annual Report Grand Challenge Projects biocatalysis.gif A model of the Michaelis complex for the TEM-1/penicillin system from molecular dynamics simulations. Investigators: P. A. Bash, Northwestern University Medical School and M. Karplus, Harvard University Research Objectives A guiding principle of molecular biology is that the structure of a biomolecule defines its function. This principle is especially true in the case

  10. Computational Fluid Dynamics

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    scour-tracc-cfd TRACC RESEARCH Computational Fluid Dynamics Computational Structural Mechanics Transportation Systems Modeling Computational Fluid Dynamics Overview of CFD: Video Clip with Audio Computational fluid dynamics (CFD) research uses mathematical and computational models of flowing fluids to describe and predict fluid response in problems of interest, such as the flow of air around a moving vehicle or the flow of water and sediment in a river. Coupled with appropriate and prototypical

  11. Protein Dynamics and Biocatalysis

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    biocatalysis.gif A model of the Michaelis complex for the TEM-1penicillin system from molecular dynamics simulations. Investigators: P. A. Bash, Northwestern University Medical...

  12. Shared and Dynamic Libraries

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Some "out-of-the-box" applications require DSLs and some popular applications like Python use DSLs as well. Using System Shared and Dynamic Libraries "System" DSLs include...

  13. Electrolyte Solvation and Ionic Association. VI. Acetonitrile...

    Office of Scientific and Technical Information (OSTI)

    different thermal phase behavior and electrochemicalphysicochemical properties. The simulation results are in full accord with a previous experimental study of these (AN)n-LiX ...

  14. Structural Interactions within Lithium Salt Solvates: Cyclic...

    Office of Scientific and Technical Information (OSTI)

    and ester solvents coordinate Li+ cations in electrolyte solutions for lithium batteries. One approach to gleaning significant insight into these interactions is to examine...

  15. Batch crystallization of rhodopsin for structural dynamics using an X-ray free-electron laser

    SciTech Connect (OSTI)

    Wu, Wenting; Nogly, Przemyslaw; Rheinberger, Jan; Kick, Leonhard M.; Gati, Cornelius; Nelson, Garrett; Deupi, Xavier; Standfuss, Jrg; Schertler, Gebhard; Panneels, Valrie

    2015-06-27

    A new batch preparation method is presented for high-density micrometre-sized crystals of the G protein-coupled receptor rhodopsin for use in time-resolved serial femtosecond crystallography at an X-ray free-electron laser using a liquid jet. Rhodopsin is a membrane protein from the G protein-coupled receptor family. Together with its ligand retinal, it forms the visual pigment responsible for night vision. In order to perform ultrafast dynamics studies, a time-resolved serial femtosecond crystallography method is required owing to the nonreversible activation of rhodopsin. In such an approach, microcrystals in suspension are delivered into the X-ray pulses of an X-ray free-electron laser (XFEL) after a precise photoactivation delay. Here, a millilitre batch production of high-density microcrystals was developed by four methodical conversion steps starting from known vapour-diffusion crystallization protocols: (i) screening the low-salt crystallization conditions preferred for serial crystallography by vapour diffusion, (ii) optimization of batch crystallization, (iii) testing the crystal size and quality using second-harmonic generation (SHG) imaging and X-ray powder diffraction and (iv) production of millilitres of rhodopsin crystal suspension in batches for serial crystallography tests; these crystals diffracted at an XFEL at the Linac Coherent Light Source using a liquid-jet setup.

  16. Solar Dynamics | Open Energy Information

    Open Energy Info (EERE)

    Dynamics Jump to: navigation, search Name: Solar Dynamics Place: Ottumwa, Iowa Zip: IA 52501 Sector: Solar Product: Solar Dynamics is a US-based solar powered attic roof vents...

  17. System Dynamics Model | NISAC

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Dynamics Model content top Chemical Supply Chain Analysis Posted by Admin on Mar 1, 2012 in | Comments 0 comments Chemical Supply Chain Analysis NISAC has developed a range of...

  18. Sandia Energy - Photodissociation Dynamics

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Photodissociation DynamicsAshley Otero2015-10-28T02:51:03+00:00 The time-resolved Fourier transform infrared emission spectrum of dicyclopropyl ketone after photodissociation...

  19. Roaming Molecule Dynamics

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    ... The recent discovery of roaming atom dynamics in the photodissociation of formaldehyde (Arthur Suits, Joel Bowman, and co-workers) led to a study at the CRF to determine whether ...

  20. Multipulsed dynamic moire interferometer

    DOE Patents [OSTI]

    Deason, Vance A. (Idaho Falls, ID)

    1991-01-01

    An improved dynamic moire interferometer comprised of a lasing medium providing a plurality of beams of coherent light, a multiple q-switch producing multiple trains of 100,000 or more pulses per second, a combining means collimating multiple trains of pulses into substantially a single train and directing beams to specimen gratings affixed to a test material, and a controller, triggering and sequencing the emission of the pulses with the occurrence and recording of a dynamic loading event.

  1. Los Alamos Dynamics Application

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Los Alamos Dynamics Summer School Application Form Do not use MAC Preview tool to edit this form as it corrupts the data. Application deadline is January 10, 2016 5:00 PM (US Mountain Standard) A complete application package includes: * This Application Form * Cover Letter - Page cover letter describing your interest in this summer school and multi-disciplinary cyber- physical dynamic systems research as well as your near term (1-3 year) academic and professional goals. * CV (resume) * One (1)

  2. EVIDENCE FOR ULTRA-FAST OUTFLOWS IN RADIO-QUIET ACTIVE GALACTIC NUCLEI. II. DETAILED PHOTOIONIZATION MODELING OF Fe K-SHELL ABSORPTION LINES

    SciTech Connect (OSTI)

    Tombesi, F.; Reeves, J. N.; Palumbo, G. G. C.; Braito, V.

    2011-11-20

    X-ray absorption line spectroscopy has recently shown evidence for previously unknown Ultra-fast Outflows (UFOs) in radio-quiet active galactic nuclei (AGNs). These have been detected essentially through blueshifted Fe XXV/XXVI K-shell transitions. In the previous paper of this series we defined UFOs as those highly ionized absorbers with an outflow velocity higher than 10,000 km s{sup -1} and assessed the statistical significance of the associated blueshifted absorption lines in a large sample of 42 local radio-quiet AGNs observed with XMM-Newton. The present paper is an extension of that work. First, we report a detailed curve of growth analysis of the main Fe XXV/XXVI transitions in photoionized plasmas. Then, we estimate an average spectral energy distribution for the sample sources and directly model the Fe K absorbers in the XMM-Newton spectra with the detailed Xstar photoionization code. We confirm that the frequency of sources in the radio-quiet sample showing UFOs is >35% and that the majority of the Fe K absorbers are indeed associated with UFOs. The outflow velocity distribution spans from {approx}10,000 km s{sup -1} ({approx}0.03c) up to {approx}100,000 km s{sup -1} ({approx}0.3c), with a peak and mean value of {approx}42,000 km s{sup -1} ({approx}0.14c). The ionization parameter is very high and in the range log {xi} {approx} 3-6 erg s{sup -1} cm, with a mean value of log {xi} {approx} 4.2 erg s{sup -1} cm. The associated column densities are also large, in the range N{sub H} {approx} 10{sup 22}-10{sup 24} cm{sup -2}, with a mean value of N{sub H} {approx} 10{sup 23} cm{sup -2}. We discuss and estimate how selection effects, such as those related to the limited instrumental sensitivity at energies above 7 keV, may hamper the detection of even higher velocities and higher ionization absorbers. We argue that, overall, these results point to the presence of extremely ionized and possibly almost Compton-thick outflowing material in the innermost regions of AGNs. This also suggests that UFOs may potentially play a significant role in the expected cosmological feedback from AGNs and their study can provide important clues on the connection between accretion disks, winds, and jets.

  3. Predicting solute partitioning in lipid bilayers: Free energies and partition coefficients from molecular dynamics simulations and COSMOmic

    SciTech Connect (OSTI)

    Jakobtorweihen, S. Ingram, T.; Gerlach, T.; Smirnova, I.; Zuniga, A. Chaides; Keil, F. J.

    2014-07-28

    Quantitative predictions of biomembrane/water partition coefficients are important, as they are a key property in pharmaceutical applications and toxicological studies. Molecular dynamics (MD) simulations are used to calculate free energy profiles for different solutes in lipid bilayers. How to calculate partition coefficients from these profiles is discussed in detail and different definitions of partition coefficients are compared. Importantly, it is shown that the calculated coefficients are in quantitative agreement with experimental results. Furthermore, we compare free energy profiles from MD simulations to profiles obtained by the recent method COSMOmic, which is an extension of the conductor-like screening model for realistic solvation to micelles and biomembranes. The free energy profiles from these molecular methods are in good agreement. Additionally, solute orientations calculated with MD and COSMOmic are compared and again a good agreement is found. Four different solutes are investigated in detail: 4-ethylphenol, propanol, 5-phenylvaleric acid, and dibenz[a,h]anthracene, whereby the latter belongs to the class of polycyclic aromatic hydrocarbons. The convergence of the free energy profiles from biased MD simulations is discussed and the results are shown to be comparable to equilibrium MD simulations. For 5-phenylvaleric acid the influence of the carboxyl group dihedral angle on free energy profiles is analyzed with MD simulations.

  4. Substructured multibody molecular dynamics.

    SciTech Connect (OSTI)

    Grest, Gary Stephen; Stevens, Mark Jackson; Plimpton, Steven James; Woolf, Thomas B. (Johns Hopkins University, Baltimore, MD); Lehoucq, Richard B.; Crozier, Paul Stewart; Ismail, Ahmed E.; Mukherjee, Rudranarayan M. (Rensselaer Polytechnic Institute, Troy, NY); Draganescu, Andrei I.

    2006-11-01

    We have enhanced our parallel molecular dynamics (MD) simulation software LAMMPS (Large-scale Atomic/Molecular Massively Parallel Simulator, lammps.sandia.gov) to include many new features for accelerated simulation including articulated rigid body dynamics via coupling to the Rensselaer Polytechnic Institute code POEMS (Parallelizable Open-source Efficient Multibody Software). We use new features of the LAMMPS software package to investigate rhodopsin photoisomerization, and water model surface tension and capillary waves at the vapor-liquid interface. Finally, we motivate the recipes of MD for practitioners and researchers in numerical analysis and computational mechanics.

  5. Dynamic cable analysis models

    SciTech Connect (OSTI)

    Palo, P.A.; Meggitt, D.J.; Nordell, W.J.

    1983-05-01

    This paper presents a summary of the development and validation of undersea cable dynamics computer models by the Naval Civil Engineering Laboratory (NCEL) under the sponsorship of the Naval Facilities Engineering Command. These models allow for the analysis of both small displacement (strumming) and large displacement (static and dynamic) deformations of arbitrarily configured cable structures. All of the large displacement models described in this paper are available to the public. This paper does not emphasize the theoretical development of the models (this information is available in other references) but emphasizes the various features of the models, the comparisons between model output and experimental data, and applications for which the models have been used.

  6. Dynamics of helium films

    SciTech Connect (OSTI)

    Clements, B.E.; Epstein, J.L.; Krotscheck, E.; Tymczak, C.J.; Saarela, M.

    1992-11-01

    The authors present quantitative calculations for the static structure and the dynamics of quantum liquid films on a translationally invariant substrate. The excitation spectrum is calculated by solving the equations of motion for time-dependent one- and two-body densities. They find significant corrections to the Feynman spectrum for the phonon-like collective excitations. 8 refs., 2 figs.

  7. Ultrafast Transformations in Superionic Nanocrystals

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    follow from their abrupt changes in ionic mobility, as well as for use as safe, efficient solid-state electrolytes for rechargeable batteries. However, the fundamental processes...

  8. Ultrafast Transformations in Superionic Nanocrystals

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Michael Faraday almost 200 years ago, superionic materials today hold promise for use in resistive switching devices, which follow from their abrupt changes in ionic mobility, as...

  9. Ultrafast Transformations in Superionic Nanocrystals

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    By subtracting the laser-off spectrum from the laser-on spectrum (at a probe delay time of 400 ps), the team obtained a differential spectrum with features corresonding to a...

  10. Ultrafast Transformations in Superionic Nanocrystals

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    their abrupt changes in ionic mobility, as well as for use as safe, efficient solid-state electrolytes for rechargeable batteries. However, the fundamental processes and...

  11. Ultrafast Transformations in Superionic Nanocrystals

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    ALS, to obtain an atomic-level, real-time view of the transition state in superionic copper sulfide (Cu2S) nanocrystals. Solid-State Ionics At the dawn of the Information Age,...

  12. LUSI :: LCLS Ultrafast Science Instruments

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    to the world of LCLS Science Meetings: LCLS SAC Meeting October 19-20, 2006 LUSI Lehman Review January 23-24, 2007 LUSI Bi-weekly Team Leader meeting June 23, 2006 LUSI...

  13. Ultra-fast laser system

    DOE Patents [OSTI]

    Dantus, Marcos; Lozovoy, Vadim V

    2014-01-21

    A laser system is provided which selectively excites Raman active vibrations in molecules. In another aspect of the present invention, the system includes a laser, pulse shaper and detection device. A further aspect of the present invention employs a femtosecond laser and binary pulse shaping (BPS). Still another aspect of the present invention uses a laser beam pulse, a pulse shaper and remote sensing.

  14. Impacts of side chain and excess energy on the charge photogeneration dynamics of low-bandgap copolymer-fullerene blends

    SciTech Connect (OSTI)

    Huo, Ming-Ming Zhang, Jian-Ping E-mail: hjhzlz@iccas.ac.cn; Department of Chemistry, Renmin University of China, Beijing 100872 ; Hu, Rong Xing, Ya-Dong Liu, Yu-Chen Ai, Xi-Cheng; Hou, Jian-Hui E-mail: hjhzlz@iccas.ac.cn

    2014-02-28

    Primary charge photogeneration dynamics in neat and fullerene-blended films of a pair of alternating benzo[1,2-b:4,5-b{sup ?}]dithiophene (BDT) and thieno[3,4-b]thiophene (TT) copolymers are comparatively studied by using near-infrared, time-resolved absorption (TA) spectroscopy under low excitation photon fluence. PBDTTT-E and PBDTTT-C, differed merely in the respective TT-substituents of ester (-E) and carbonyl (-C), show distinctly different charge photogeneration dynamics. The pair of neat PBDTTT films show exciton lifetimes of ?0.1 ns and fluorescence quantum yields below 0.2%, as well as prominent excess-energy enhanced exciton dissociation. In addition, PBDTTT-C gives rise to >50% higher P{sup +} yield than PBDTTT-E does irrespective to the excitation photon energy. Both PBDTTT-E:PC{sub 61}BM and PBDTTT-C:PC{sub 61}BM blends show subpicosecond exciton lifetimes and nearly unitary fluorescence quenching efficiency and, with respect to the former blend, the latter one shows substantially higher branching ratio of charge separated (CS) state over interfacial charge transfer (ICT) state, and hence more efficient exciton-to-CS conversion. For PBDTTT-C:PC{sub 61}BM, the ultrafast charge dynamics clearly show the processes of ICT-CS interconversion and P{sup +} migration, which are possibly influenced by the ICT excess energy. However, such processes are relatively indistinctive in the case of PBDTTT-E:PC{sub 61}BM. The results strongly prove the importance of ICT dissociation in yielding free charges, and are discussed in terms of the film morphology and the precursory solution-phase macromolecular conformation.

  15. Entanglement dynamics in chaotic systems

    SciTech Connect (OSTI)

    Ghose, Shohini [Institute for Quantum Information Science, University of Calgary, Alberta, T2N 1N4 (Canada); Department of Physics and Astronomy, University of New Mexico, Albuquerque, New Mexico 87131 (United States); Sanders, Barry C. [Institute for Quantum Information Science, University of Calgary, Alberta, T2N 1N4 (Canada); Centre for Quantum Computer Technology, Macquarie University, Sydney, New South Wales (Australia)

    2004-12-01

    We study quantum chaos for systems with more than one degree of freedom, for which we present an analysis of the dynamics of entanglement. Our analysis explains the main features of entanglement dynamics and identifies entanglement-based signatures of quantum chaos. We discuss entanglement dynamics for a feasible experiment involving an atom in a magneto-optical trap and compare the results with entanglement dynamics for the well-studied quantum kicked top.

  16. Fluid Dynamics and Solid Mechanics

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    and Solid Mechanics Basic and applied research in theoretical continuum dynamics, modern hydrodynamic theory, materials modeling, global climate modeling, numerical...

  17. Roaming Molecule Dynamics

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Roaming Molecule Dynamics - Sandia Energy Energy Search Icon Sandia Home Locations Contact Us Employee Locator Energy & Climate Secure & Sustainable Energy Future Stationary Power Energy Conversion Efficiency Solar Energy Wind Energy Water Power Supercritical CO2 Geothermal Natural Gas Safety, Security & Resilience of the Energy Infrastructure Energy Storage Nuclear Power & Engineering Grid Modernization Battery Testing Nuclear Fuel Cycle Defense Waste Management Programs

  18. Dynamic Windows Program

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Dynamic Windows Program 2014 Building Technologies Office Peer Review Robert C. Tenent, robert.tenent@nrel.gov National Renewable Energy Laboratory Project Summary Timeline: Start date: October, 2009 Planned end date: September, 2014 Key Milestones 1. Transfer next generation materials to Sage Electrochromics (09/2013) 2. Formation of a laminated electrochromic device employing a PVB based gel electrolyte layer and initial testing under inert condition.(09/2013) 3. Demonstrate new reflective

  19. Dynamic radioactive particle source

    DOE Patents [OSTI]

    Moore, Murray E.; Gauss, Adam Benjamin; Justus, Alan Lawrence

    2012-06-26

    A method and apparatus for providing a timed, synchronized dynamic alpha or beta particle source for testing the response of continuous air monitors (CAMs) for airborne alpha or beta emitters is provided. The method includes providing a radioactive source; placing the radioactive source inside the detection volume of a CAM; and introducing an alpha or beta-emitting isotope while the CAM is in a normal functioning mode.

  20. Beam Dynamics for ARIA

    SciTech Connect (OSTI)

    Ekdahl, Carl August Jr.

    2014-10-14

    Beam dynamics issues are assessed for a new linear induction electron accelerator being designed for flash radiography of large explosively driven hydrodynamic experiments. Special attention is paid to equilibrium beam transport, possible emittance growth, and beam stability. It is concluded that a radiographic quality beam will be produced possible if engineering standards and construction details are equivalent to those on the present radiography accelerators at Los Alamos.

  1. Dynamical impurity problems

    SciTech Connect (OSTI)

    Emery, V.J.; Kivelson, S.A.

    1993-12-31

    In the past few years there has been a resurgence of interest in dynamical impurity problems, as a result of developments in the theory of correlated electron systems. The general dynamical impurity problem is a set of conduction electrons interacting with an impurity which has internal degrees of freedom. The simplest and earliest example, the Kondo problem, has attracted interest since the mid-sixties not only because of its physical importance but also as an example of a model displaying logarithmic divergences order by order in perturbation theory. It provided one of the earliest applications of the renormalization group method, which is designed to deal with just such a situation. As we shall see, the antiferromagnetic Kondo model is controlled by a strong-coupling fixed point, and the essence of the renormalization group solution is to carry out the global renormalization numerically starting from the original (weak-coupling) Hamiltonian. In these lectures, we shall describe an alternative route in which we identify an exactly solvable model which renormalizes to the same fixed point as the original dynamical impurity problem. This approach is akin to determining the critical behavior at a second order phase transition point by solving any model in a given universality class.

  2. Photo-modulated thin film transistor based on dynamic charge transfer within quantum-dots-InGaZnO interface

    SciTech Connect (OSTI)

    Liu, Xiang; Yang, Xiaoxia; Liu, Mingju; Tao, Zhi; Wei, Lei Li, Chi Zhang, Xiaobing; Wang, Baoping; Dai, Qing; Nathan, Arokia

    2014-03-17

    The temporal development of next-generation photo-induced transistor across semiconductor quantum dots and Zn-related oxide thin film is reported in this paper. Through the dynamic charge transfer in the interface between these two key components, the responsibility of photocurrent can be amplified for scales of times (?10{sup 4}?A/W 450?nm) by the electron injection from excited quantum dots to InGaZnO thin film. And this photo-transistor has a broader waveband (from ultraviolet to visible light) optical sensitivity compared with other Zn-related oxide photoelectric device. Moreover, persistent photoconductivity effect can be diminished in visible waveband which lead to a significant improvement in the device's relaxation time from visible illuminated to dark state due to the ultrafast quenching of quantum dots. With other inherent properties such as integrated circuit compatible, low off-state current and high external quantum efficiency resolution, it has a great potential in the photoelectric device application, such as photodetector, phototransistor, and sensor array.

  3. Effect of deuterium substitution for hydrogen in surface functionalisation of hydrophilic nanosilicon particles on their spectral and dynamic properties

    SciTech Connect (OSTI)

    Kompanets, V O; Chekalin, S V; Dorofeev, S G; Kononov, N N; Barzilovich, P Yu; Ishchenko, A A

    2014-06-30

    Broadband femtosecond spectroscopy has been used to study two types of hydrophilic silicon nanoparticles: (1) photoluminescent, passivated with deuterium and oxidised in fully deuterated dimethyl sulphoxide, and (2) nonluminescent (control samples having a similar crystalline core), passivated with hydrogen and oxidised in dimethyl sulphoxide. We have found significant differences in ultrafast spectral temporal induced absorption dynamics between the two types of nanoparticles in the energy range corresponding to their calculated band gap. The observed distinction is due to the considerably higher oxidation rate of silicon on the surface of the deuterated samples in comparison with the undeuterated ones and with the associated increase in the number of photoluminescence centres on the surface of the nanoparticles. In the samples containing self-trapped exciton (STE) energy states responsible for the photoluminescence in the red spectral region, carrier capture at these levels and carrier relaxation to the ground state have characteristic times in the femtosecond range. In the samples free of STE states, excited carriers relax to the conduction band bottom in a characteristic time of several picoseconds. (extreme light fields and their applications)

  4. Dynamic Underground Stripping Project

    SciTech Connect (OSTI)

    Aines, R.; Newmark, R.; McConachie, W.; Udell, K.; Rice, D.; Ramirez, A.; Siegel, W.; Buettner, M.; Daily, W.; Krauter, P.; Folsom, E.; Boegel, A.J.; Bishop, D.; Udell, K.

    1992-01-01

    LLNL is collaborating with the UC Berkeley College of Engineering to develop and demonstrate a system of thermal remediation and underground imaging techniques for use in rapid cleanup of localized underground spills. Called ``Dynamic Stripping`` to reflect the rapid and controllable nature of the process, it will combine steam injection, direct electrical heating, and tomographic geophysical imaging in a cleanup of the LLNL gasoline spill. In the first 8 months of the project, a Clean Site engineering test was conducted to prove the field application of the techniques before moving the contaminated site in FY 92.

  5. Cantera Aerosol Dynamics Simulator

    Energy Science and Technology Software Center (OSTI)

    2004-09-01

    The Cantera Aerosol Dynamics Simulator (CADS) package is a general library for aerosol modeling to address aerosol general dynamics, including formation from gas phase reactions, surface chemistry (growth and oxidation), bulk particle chemistry, transport by Brownian diffusion, thermophoresis, and diffusiophoresis with linkage to DSMC studies, and thermal radiative transport. The library is based upon Cantera, a C++ Cal Tech code that handles gas phase species transport, reaction, and thermodynamics. The method uses a discontinuous galerkinmore » formulation for the condensation and coagulation operator that conserves particles, elements, and enthalpy up to round-off error. Both O-D and 1-D time dependent applications have been developed with the library. Multiple species in the solid phase are handled as well. The O-D application, called Tdcads (Time Dependent CADS) is distributed with the library. Tdcads can address both constant volume and constant pressure adiabatic homogeneous problems. An extensive set of sample problems for Tdcads is also provided.« less

  6. State-of-the Art Simulations of Liquid Phenomena | Argonne Leadership...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    32 water molecules The image shows a nitrate anion solvated by 32 water molecules after a molecular dynamics simulation. Spencer Pruitt, Argonne National Laboratory State-of-the...

  7. Los Alamos Dynamics Summer School

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Los Alamos Dynamics Summer School The Seventeenth Los Alamos Dynamics Summer School School overview and focus. Contact Institute Director Charles Farrar (505) 665-0860 Email Executive Administrator Ellie Vigil (505) 667-2818 Email Administrative Assistant Rebecca Duran (505) 665-8899 Email The Los Alamos Dynamics Summer School is a very selective summer school in which top upper-level US-citizen undergraduate students from universities around the nation attend lectures and work in teams of three

  8. Los Alamos Dynamics Summer School

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Los Alamos Dynamics Summer School » Los Alamos Dynamics Summer School The Seventeenth Los Alamos Dynamics Summer School Program Information and Application Process Contact Institute Director Charles Farrar (505) 665-0860 Email Executive Administrator Ellie Vigil (505) 667-2718 Email Administrative Assistant Rebecca Duran (505) 665-8899 Email How to Apply Students should email the following documents to LADSSApply@lanl.gov Application Form (pdf) A one-page cover letter describing your interest

  9. Los Alamos Dynamics Summer School

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    The Seventeenth Los Alamos Dynamics Summer School Program Information and Application Process Contact Institute Director Charles Farrar (505) 663-5330 Email Executive...

  10. Dynamic bed reactor

    DOE Patents [OSTI]

    Stormo, Keith E. (Moscow, ID)

    1996-07-02

    A dynamic bed reactor is disclosed in which a compressible open cell foam matrix is periodically compressed and expanded to move a liquid or fluid through the matrix. In preferred embodiments, the matrix contains an active material such as an enzyme, biological cell, chelating agent, oligonucleotide, adsorbent or other material that acts upon the liquid or fluid passing through the matrix. The active material may be physically immobilized in the matrix, or attached by covalent or ionic bonds. Microbeads, substantially all of which have diameters less than 50 microns, can be used to immobilize the active material in the matrix and further improve reactor efficiency. A particularly preferred matrix is made of open cell polyurethane foam, which adsorbs pollutants such as polychlorophenol or o-nitrophenol. The reactors of the present invention allow unidirectional non-laminar flow through the matrix, and promote intimate exposure of liquid reactants to active agents such as microorganisms immobilized in the matrix.

  11. Dynamic Information Architecture System

    Energy Science and Technology Software Center (OSTI)

    1997-02-12

    The Dynamic Information System (DIAS) is a flexible object-based software framework for concurrent, multidiscplinary modeling of arbitrary (but related) processes. These processes are modeled as interrelated actions caused by and affecting the collection of diverse real-world objects represented in a simulation. The DIAS architecture allows independent process models to work together harmoniously in the same frame of reference and provides a wide range of data ingestion and output capabilities, including Geographic Information System (GIS) typemore » map-based displays and photorealistic visualization of simulations in progress. In the DIAS implementation of the object-based approach, software objects carry within them not only the data which describe their static characteristics, but also the methods, or functions, which describe their dynamic behaviors. There are two categories of objects: (1) Entity objects which have real-world counterparts and are the actors in a simulation, and (2) Software infrastructure objects which make it possible to carry out the simulations. The Entity objects contain lists of Aspect objects, each of which addresses a single aspect of the Entity''s behavior. For example, a DIAS Stream Entity representing a section of a river can have many aspects correspondimg to its behavior in terms of hydrology (as a drainage system component), navigation (as a link in a waterborne transportation system), meteorology (in terms of moisture, heat, and momentum exchange with the atmospheric boundary layer), and visualization (for photorealistic visualization or map type displays), etc. This makes it possible for each real-world object to exhibit any or all of its unique behaviors within the context of a single simulation.« less

  12. Dynamic granularity of imaging systems

    SciTech Connect (OSTI)

    Geissel, Matthias; Smith, Ian C.; Shores, Jonathon E.; Porter, John L.

    2015-11-04

    Imaging systems that include a specific source, imaging concept, geometry, and detector have unique properties such as signal-to-noise ratio, dynamic range, spatial resolution, distortions, and contrast. Some of these properties are inherently connected, particularly dynamic range and spatial resolution. It must be emphasized that spatial resolution is not a single number but must be seen in the context of dynamic range and consequently is better described by a function or distribution. We introduce the dynamic granularity Gdyn as a standardized, objective relation between a detectors spatial resolution (granularity) and dynamic range for complex imaging systems in a given environment rather than the widely found characterization of detectors such as cameras or films by themselves. We found that this relation can partly be explained through consideration of the signals photon statistics, background noise, and detector sensitivity, but a comprehensive description including some unpredictable data such as dust, damages, or an unknown spectral distribution will ultimately have to be based on measurements. Measured dynamic granularities can be objectively used to assess the limits of an imaging systems performance including all contributing noise sources and to qualify the influence of alternative components within an imaging system. Our article explains the construction criteria to formulate a dynamic granularity and compares measured dynamic granularities for different detectors used in the X-ray backlighting scheme employed at Sandias Z-Backlighter facility.

  13. Molecular dynamics simulation of diffusion coefficients and structural properties of some alkylbenzenes in supercritical carbon dioxide at infinite dilution

    SciTech Connect (OSTI)

    Wang, Jinyang; Zhong, Haimin; Qiu, Wenda; Chen, Liuping; Feng, Huajie

    2014-03-14

    The binary infinite dilute diffusion coefficients, D{sub 12}{sup ?}, of some alkylbenzenes (Ph-C{sub n}, from Ph-H to Ph-C{sub 12}) from 313 K to 333 K at 15 MPa in supercritical carbon dioxide (scCO{sub 2}) have been studied by molecular dynamics (MD) simulation. The MD values agree well with the experimental ones, which indicate MD simulation technique is a powerful way to predict and obtain diffusion coefficients of solutes in supercritical fluids. Besides, the local structures of Ph-C{sub n}/CO{sub 2} fluids are further investigated by calculating radial distribution functions and coordination numbers. It qualitatively convinces that the first solvation shell of Ph-C{sub n} in scCO{sub 2} is significantly influenced by the structure of Ph-C{sub n} solute. Meanwhile, the mean end-to-end distance, the mean radius of gyration and dihedral angle distribution are calculated to gain an insight into the structural properties of Ph-C{sub n} in scCO{sub 2}. The abnormal trends of radial distribution functions and coordination numbers can be reasonably explained in term of molecular flexibility. Moreover, the computed results of dihedral angle clarify that flexibility of long-chain Ph-C{sub n} is the result of internal rotation of C-C single bond (?{sub c-c}) in alkyl chain. It is interesting that compared with n-alkane, because of the existence of benzene ring, the flexibility of alkyl chain in Ph-C{sub n} with same carbon atom number is significantly reduced, as a result, the carbon chain dependence of diffusion behaviors for long-chain n-alkane (n ? 5) and long-chain Ph-C{sub n} (n ? 4) in scCO{sub 2} are different.

  14. Atomistic Time-Domain Simulations of Light-Harvesting and Charge-Transfer Dynamics in Novel Nanoscale Materials for Solar Hydrogen Production.

    SciTech Connect (OSTI)

    Prezhdo, Oleg V.

    2012-03-22

    Funded by the DOE grant (i) we continued to study and analyze the atomistic detail of the electron transfer (ET) across the chromophore-TiO2 interface in Gratzel cell systems for solar hydrogen production. (ii) We extensively investigated the nature of photoexcited states and excited state dynamics in semiconductor quantum dots (QD) designed for photovoltaic applications. (iii) We continued a newly initiated research direction focusing on excited state properties and electron-phonon interactions in nanoscale carbon materials. Over the past year, the results of the DOE funded research were summarized in 3 review articles. 12 original manuscripts were written. The research results were reported in 28 invited talks at conferences and university seminars. 20 invitations were accepted for talks in the near future. 2 symposia at national and international meetings have being organized this year on topics closely related to the DOE funded project, and 2 more symposia have been planned for the near future. We summarized the insights into photoinduced dynamics of semiconductor QDs, obtained from our time-domain ab initio studies. QDs exhibit both molecular and bulk properties. Unlike either bulk or molecular materials, QD properties can be modified continuously by changing QD shape and size. However, the chemical and physical properties of molecular and bulk materials often contradict each other, which can lead to differing viewpoints about the behavior of QDs. For example, the molecular view suggests strong electron-hole and charge-phonon interactions, as well as slow energy relaxation due to mismatch between electronic energy gaps and phonon frequencies. In contrast, the bulk view advocates that the kinetic energy of quantum confinement is greater than electron-hole interactions, that charge-phonon coupling is weak, and that the relaxation through quasi-continuous bands is rapid. By synthesizing the bulk and molecular viewpoints, we clarified the controversies and provided a unified atomistic picture of the nature and dynamics of photoexcited states in semiconductor QDs. We also summarized our recent findings about the photoinduced electron dynamics at the chromophore-semiconductor interfaces from a time-domain ab initio perspective. The interface provides the foundation for a new, promising type of solar cell and presents a fundamentally important case study for several fields, including photo-, electro- and analytical chemistries, molecular electronics, and photography. Further, the interface offers a classic example of an interaction between an organic molecular species and an inorganic bulk material. Scientists employ different concepts and terminologies to describe molecular and solid states of matter, and these differences make it difficult to describe the interface with a single model. At the basic atomistic level of description, however, this challenge can be largely overcome. Recent advances in non-adiabatic molecular dynamics and time-domain density functional theory have created a unique opportunity for simulating the ultrafast, photoinduced processes on a computer very similar to the way that they occur in nature. These state-of-the-art theoretical tools offered a comprehensive picture of a variety of electron transfer processes that occur at the interface, including electron injection from the chromophore to the semiconductor, electron relaxation and delocalization inside the semiconductor, back-transfer of the electron to the chromophore and to the electrolyte, and regeneration of the neutral chromophore by the electrolyte. The ab initio time-domain modeling is particularly valuable for understanding these dynamic features of the ultrafast electron transfer processes, which cannot be represented by a simple rate description. We demonstrated using symmetry adapted cluster theory with configuration interaction (SAC-CI) that charging of small PbSe nanocrystals (NCs) greatly modifies their electronic states and optical excitations. Conduction and valence band transitions that are not available in neutral NCs dominate

  15. ICFA Beam Dynamics Newsletter

    SciTech Connect (OSTI)

    Ben-Zvi I.; Kuczewski A.; Altinbas, Z.; Beavis, D.; Belomestnykh,; Dai, J. et al

    2012-07-01

    The Collider-Accelerator Department at Brookhaven National Laboratory is building a high-brightness 500 mA capable Energy Recovery Linac (ERL) as one of its main R&D thrusts towards eRHIC, the polarized electron - hadron collider as an upgrade of the operating RHIC facility. The ERL is in final assembly stages, with injection commisioning starting in October 2012. The objective of this ERL is to serve as a platform for R&D into high current ERL, in particular issues of halo generation and control, Higher-Order Mode (HOM) issues, coherent emissions for the beam and high-brightness, high-power beam generation and preservation. The R&D ERL features a superconducting laser-photocathode RF gun with a high quantum efficiency photoccathode served with a load-lock cathode delivery system, a highly damped 5-cell accelerating cavity, a highly flexible single-pass loop and a comprehensive system of beam instrumentation. In this ICFA Beam Dynamics Newsletter article we will describe the ERL in a degree of detail that is not usually found in regular publications. We will discuss the various systems of the ERL, following the electrons from the photocathode to the beam dump, cover the control system, machine protection etc and summarize with the status of the ERL systems.

  16. Computational Fluid Dynamics Library

    Energy Science and Technology Software Center (OSTI)

    2005-03-04

    CFDLib05 is the Los Alamos Computational Fluid Dynamics LIBrary. This is a collection of hydrocodes using a common data structure and a common numerical method, for problems ranging from single-field, incompressible flow, to multi-species, multi-field, compressible flow. The data structure is multi-block, with a so-called structured grid in each block. The numerical method is a Finite-Volume scheme employing a state vector that is fully cell-centered. This means that the integral form of the conservation lawsmore » is solved on the physical domain that is represented by a mesh of control volumes. The typical control volume is an arbitrary quadrilateral in 2D and an arbitrary hexahedron in 3D. The Finite-Volume scheme is for time-unsteady flow and remains well coupled by means of time and space centered fluxes; if a steady state solution is required, the problem is integrated forward in time until the user is satisfied that the state is stationary.« less

  17. Fluid Dynamics with Free Surfaces

    Energy Science and Technology Software Center (OSTI)

    1992-02-01

    RIPPLE is a two-dimensional, transient, free surface incompressible fluid dynamics program. It allows multiple free surfaces with surface tension and wall adhesion forces and has a partial cell treatment which allows curved boundaries and interior obstacles.

  18. Dynamic Worldwide Solar Energy | Open Energy Information

    Open Energy Info (EERE)

    Worldwide Solar Energy Jump to: navigation, search Name: Dynamic Worldwide Solar Energy Sector: Solar Product: US-based solar developer and financer. References: Dynamic Worldwide...

  19. Dynamics of Molecular Clouds: Observations, Simulations, and...

    Office of Scientific and Technical Information (OSTI)

    Conference: Dynamics of Molecular Clouds: Observations, Simulations, and NIF Experiments Citation Details In-Document Search Title: Dynamics of Molecular Clouds: Observations,...

  20. Soil Machine Dynamics Ltd | Open Energy Information

    Open Energy Info (EERE)

    Machine Dynamics Ltd Jump to: navigation, search Name: Soil Machine Dynamics Ltd Region: United Kingdom Sector: Marine and Hydrokinetic Website: http: This company is listed in the...

  1. Dynamical symmetries in nuclear structure

    SciTech Connect (OSTI)

    Casten, R.F.

    1986-01-01

    In recent years the concept of dynamical symmetries in nuclei has witnessed a renaissance of interest and activity. Much of this work has been developed in the context of the Interacting Boson Approximation (or IBA) model. The appearance and properties of dynamical symmetries in nuclei will be reviewed, with emphasis on their characteristic signatures and on the role of the proton-neutron interaction in their formation, systematics and evolution. 36 refs., 20 figs.

  2. HAWT performance with dynamic stall

    SciTech Connect (OSTI)

    Hibbs, B.D.

    1986-02-01

    In this report we calculated the effects of flow nonuniformities (wing shear, tower wake, yaw, and large-scale turbulence) on the performance of a horizontal axis wind turbine, accounting for dynamic stall. We modified the PROP program to incorporate and compare these effects with the uniform flow case. The MIT model, which predicts dynamic lift coefficients substantially higher than the static maximum values and includes a crude model of the vortex roll-off phenomenon, represented dynamic stall. As associated model for drag was also used. The dynamic stall model was tested against experimental data for three typical reduced frequencies. Good instantaneous correlation was obtained. The effects of nonuniformities with and without the dynamic stall were calculated using the Westinghouse Mod O and Enertech 44/25 turbines. Modeling the dynamic stall has little effect on performance. Furthermore, the performance with nonuniform flow differed only slightly from the uniform flow case. Thus the now PROP model provides a powerful general capability to handle nonuniform flows.

  3. Femtosecond photoelectron spectroscopy: a new tool for the study of anion dynamics

    SciTech Connect (OSTI)

    Greenblatt, B.J.

    1999-02-01

    A new experimental technique for the time-resolved study of anion reactions is presented. Using femtosecond laser pulses, which provide extremely fast ({approx} 100 fs) time resolution, in conjunction with photoelectron spectroscopy, which reveals differences between anion and neutral potential energy surfaces, a complex anion reaction can be followed from its inception through the formation of asymptotic products. Experimental data can be modeled quantitatively using established theoretical approaches, allowing for the refinement of potential energy surfaces as well as dynamical models. After a brief overview, a detailed account of the construction of the experimental apparatus is presented. Documentation of the data acquisition program is contained in the Appendix. The first experimental demonstration of the technique is then presented for I{sub 2}{sup -} photodissociation, modeled using a simulation program which is also detailed in the Appendix. The investigation of I{sub 2}{sup -} photodissociation in several size-selected I{sub 2}{sup -}(Ar){sub n} (n = 6-20) and I{sub 2}{sup -}(CO{sub 2}){sub n} (n = 4-16) clusters forms the heart of the dissertation. In a series of chapters, the numerous effects of solvation on this fundamental bond-breaking reaction are explored, the most notable of which is the recombination of I{sub 2}{sup -} on the ground {tilde X}({sup 2}{Sigma}{sub u}{sup +}) state in sufficiently large clusters. Recombination and trapping of I{sub 2}{sup -} on the excited {tilde A}({sup 2}{Pi}{sub 3/2,g}) state is also observed in both types of clusters. The studies have revealed electronic state transitions, the first step in recombination, on a {approx}500 fs to {approx}10 ps timescale. Accompanying the changes in electronic state is solvent reorganization, which occurs on a similar timescale. Over longer periods ({approx}1 ps to >200 ps), energy is transferred from vibrationally excite d I{sub 2}{sup -} to modes of the solvent, which in turn leads to solvent evaporation. These effects become more important as cluster size increases. In addition, differences in timescale and mechanism are observed between clusters of Ar, which binds to I{sup -} and I{sub 2}{sup -} rather weakly, and CO{sub 2}, whose large quadruple moment allows substantially stronger binding to these anions.

  4. Wed Thu Fri Sat Sun

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    NdNiO3 interface: charge-order dynamics LF16 XPP GAFFNEY, KELLY Observing ligand torsion dynamics in a solvated Cu(I)(diimine)2+ compound to understand excited-state dynamics...

  5. Simple Dynamic Gasifier Model That Runs in Aspen Dynamics

    SciTech Connect (OSTI)

    Robinson, P.J.; Luyben, W.L.

    2008-10-15

    Gasification (or partial oxidation) is a vital component of 'clean coal' technology. Sulfur and nitrogen emissions can be reduced, overall energy efficiency is increased, and carbon dioxide recovery and sequestration are facilitated. Gasification units in an electric power generation plant produce a fuel for driving combustion turbines. Gasification units in a chemical plant generate gas, which can be used to produce a wide spectrum of chemical products. Future plants are predicted to be hybrid power/chemical plants with gasification as the key unit operation. The widely used process simulator Aspen Plus provides a library of models that can be used to develop an overall gasifier model that handles solids. So steady-state design and optimization studies of processes with gasifiers can be undertaken. This paper presents a simple approximate method for achieving the objective of having a gasifier model that can be exported into Aspen Dynamics. The basic idea is to use a high molecular weight hydrocarbon that is present in the Aspen library as a pseudofuel. This component should have the same 1:1 hydrogen-to-carbon ratio that is found in coal and biomass. For many plantwide dynamic studies, a rigorous high-fidelity dynamic model of the gasifier is not needed because its dynamics are very fast and the gasifier gas volume is a relatively small fraction of the total volume of the entire plant. The proposed approximate model captures the essential macroscale thermal, flow, composition, and pressure dynamics. This paper does not attempt to optimize the design or control of gasifiers but merely presents an idea of how to dynamically simulate coal gasification in an approximate way.

  6. Dynamics of femtosecond laser produced tungsten nanoparticle plumes

    SciTech Connect (OSTI)

    Harilal, S. S.; Hassanein, A.; Farid, N.; School of Physics and Optical Engineering, Dalian University of Technology, Dalian 116024 ; Kozhevin, V. M.

    2013-11-28

    We investigated the expansion features of femtosecond laser generated tungsten nanoparticle plumes in vacuum. Fast gated images showed distinct two components expansion features, viz., plasma and nanoparticle plumes, separated by time of appearance. The persistence of plasma and nanoparticle plumes are ?500 ns and ?100 ?s, respectively, and propagating with velocities differed by 25 times. The estimated temperature of the nanoparticles showed a decreasing trend with increasing time and space. Compared to low-Z materials (e.g., Si), ultrafast laser ablation of high-Z materials like W provides significantly higher nanoparticle yield. A comparison between the nanoparticle plumes generated by W and Si is also discussed along with other metals.

  7. Uncovering the Operating Principles of Photoelectrodes

    SciTech Connect (OSTI)

    2015-12-01

    NREL Highlights Fact Sheet: NREL scientists developed an ultrafast spectroscopic probe that is specifically sensitive to the carrier dynamics at critically important interfaces.

  8. Shock compression of precompressed deuterium (Conference) | SciTech...

    Office of Scientific and Technical Information (OSTI)

    VA at www.ntis.gov. Here we report quasi-isentropic dynamic compression and thermodynamic characterization of solid, precompressed deuterium over an ultrafast time scale (< 100 ps)...

  9. Haidan Wen | Argonne National Laboratory

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    and Technology of China in 2001. Dr. Wen's research is focused on investigating ultrafast dynamics of multiple degrees of freedom such as lattice, charge, spin and magnetic orders...

  10. 2D heterodyne-detected sum frequency generation study on the...

    Office of Scientific and Technical Information (OSTI)

    sum frequency generation study on the ultrafast vibrational dynamics of Hsub 2O and HOD water at charged interfaces Citation Details In-Document Search Title:...

  11. Dr. Naomi Ginsberg | Photosynthetic Antenna Research Center

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Naomi Ginsberg October 17, 2013 Dr. Naomi Ginsberg Imaging heterogeneous ultrafast exciton dynamics in organic semiconducting thin films Published: October 17, 2013

  12. Dynamics of Block Copolymer Nanocomposites

    SciTech Connect (OSTI)

    Mochrie, Simon G. J.

    2014-09-09

    A detailed study of the dynamics of cadmium sulfide nanoparticles suspended in polystyrene homopolymer matrices was carried out using X-ray photon correlation spectroscopy for temperatures between 120 and 180 C. For low molecular weight polystyrene homopolymers, the observed dynamics show a crossover from diffusive to hyper-diffusive behavior with decreasing temperatures. For higher molecular weight polystyrene, the nanoparticle dynamics appear hyper-diffusive at all temperatures studied. The relaxation time and characteristic velocity determined from the measured hyper-diffusive dynamics reveal that the activation energy and underlying forces determined are on the order of 2.14 10?19 J and 87 pN, respectively. We also carried out a detailed X-ray scattering study of the static and dynamic behavior of a styrene isoprene diblock copolymer melt with a styrene volume fraction of 0.3468. At 115 and 120 C, we observe splitting of the principal Bragg peak, which we attribute to phase coexistence of hexagonal cylindrical and cubic double- gyroid structure. In the disordered phase, above 130 C, we have characterized the dynamics of composition fluctuations via X-ray photon correlation spectroscopy. Near the peak of the static structure factor, these fluctuations show stretched-exponential relaxations, characterized by a stretching exponent of about 0.36 for a range of temperatures immediately above the MST. The corresponding characteristic relaxation times vary exponentially with temperature, changing by a factor of 2 for each 2 C change in temperature. At low wavevectors, the measured relaxations are diffusive with relaxation times that change by a factor of 2 for each 8 C change in temperature.

  13. Fairness and dynamic pricing: comments

    SciTech Connect (OSTI)

    Hogan, William W.

    2010-07-15

    In ''The Ethics of Dynamic Pricing,'' Ahmad Faruqui lays out a case for improved efficiency in using dynamic prices for retail electricity tariffs and addresses various issues about the distributional effects of alternative pricing mechanisms. The principal contrast is between flat or nearly constant energy prices and time-varying prices that reflect more closely the marginal costs of energy and capacity. The related issues of fairness criteria, contracts, risk allocation, cost allocation, means testing, real-time pricing, and ethical policies of electricity market design also must be considered. (author)

  14. Dynamical systems probabilistic risk assessment.

    SciTech Connect (OSTI)

    Denman, Matthew R.; Ames, Arlo Leroy

    2014-03-01

    Probabilistic Risk Assessment (PRA) is the primary tool used to risk-inform nuclear power regulatory and licensing activities. Risk-informed regulations are intended to reduce inherent conservatism in regulatory metrics (e.g., allowable operating conditions and technical specifications) which are built into the regulatory framework by quantifying both the total risk profile as well as the change in the risk profile caused by an event or action (e.g., in-service inspection procedures or power uprates). Dynamical Systems (DS) analysis has been used to understand unintended time-dependent feedbacks in both industrial and organizational settings. In dynamical systems analysis, feedback loops can be characterized and studied as a function of time to describe the changes to the reliability of plant Structures, Systems and Components (SSCs). While DS has been used in many subject areas, some even within the PRA community, it has not been applied toward creating long-time horizon, dynamic PRAs (with time scales ranging between days and decades depending upon the analysis). Understanding slowly developing dynamic effects, such as wear-out, on SSC reliabilities may be instrumental in ensuring a safely and reliably operating nuclear fleet. Improving the estimation of a plant's continuously changing risk profile will allow for more meaningful risk insights, greater stakeholder confidence in risk insights, and increased operational flexibility.

  15. Dissecting ion-specific dielectric spectra of sodium-halide solutions into

    Office of Scientific and Technical Information (OSTI)

    solvation water and ionic contributions (Journal Article) | SciTech Connect Dissecting ion-specific dielectric spectra of sodium-halide solutions into solvation water and ionic contributions Citation Details In-Document Search Title: Dissecting ion-specific dielectric spectra of sodium-halide solutions into solvation water and ionic contributions Using extensive equilibrium molecular dynamics simulations we determine the dielectric spectra of aqueous solutions of NaF, NaCl, NaBr, and NaI.

  16. reactive ion solvation and solid-liquid interfacial reactions...

    Office of Scientific and Technical Information (OSTI)

    Resource Type: Conference Resource Relation: Conference: Ions in Aqueous Solutions and Molecular Biology: Theory, simulation, modelling held July 9-12, 2012 in Telluride, CO.; ...

  17. Linking Ion Solvation and Lithium Battery Electrolyte Properties...

    Broader source: Energy.gov (indexed) [DOE]

    & Publications Inexpensive, Nonfluorinated (or Partially Fluorinated) Anions for Lithium Salts and Ionic Liquids for Lithium Battery Electrolytes Inexpensive, Nonfluorinated...

  18. Anomalous Density Properties and Ion Solvation in Liquid Water...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    to a number of fields, ranging from biologybiochemistry to energy storage and electrochemistry. Several key properties of water, are crucial for understanding and predicting...

  19. Ionic strength independence of charge distributions in solvation...

    Office of Scientific and Technical Information (OSTI)

    surrounding the biomolecules, as well as the contributions of ions to the electrostatic free energy of interaction between the biomolecule and the surrounding salt solution (for...

  20. Final Progress Report for Linking Ion Solvation and Lithium Battery...

    Office of Scientific and Technical Information (OSTI)

    in bulk electrolytes through a synergistic experimental approach involving three research thrusts complements work by other researchers to optimize multi-solvent...

  1. Lithium Ion Solvation and Diffusion in Bulk Organic Electrolytes...

    Office of Scientific and Technical Information (OSTI)

    Relation: Conference: Presented at: ACS Spring Meeting 2015, Denver, CO, United States, Mar 22 - Mar 26, 2015 Research Org: Lawrence Livermore National Laboratory (LLNL),...

  2. Slow Dynamics of Orbital Domains in Manganite

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Slow Dynamics of Orbital Domains in Manganite Slow Dynamics of Orbital Domains in Manganite Print Wednesday, 25 June 2008 00:00 At the ALS, an international team of researchers has...

  3. HelioDynamics Ltd | Open Energy Information

    Open Energy Info (EERE)

    HelioDynamics Ltd Jump to: navigation, search Name: HelioDynamics Ltd Place: Cambridge, United Kingdom Zip: CB23 2SH Sector: Solar Product: Manufactures the HD211 product - a solar...

  4. Predissociation dynamics of lithium iodide

    SciTech Connect (OSTI)

    Schmidt, H.; Vangerow, J. von; Stienkemeier, F.; Mudrich, M.; Bogomolov, A. S.; Baklanov, A. V.; Reich, D. M.; Skomorowski, W.; Koch, C. P.

    2015-01-28

    The predissociation dynamics of lithium iodide (LiI) in the first excited A-state is investigated for molecules in the gas phase and embedded in helium nanodroplets, using femtosecond pump-probe photoionization spectroscopy. In the gas phase, the transient Li{sup +} and LiI{sup +} ion signals feature damped oscillations due to the excitation and decay of a vibrational wave packet. Based on high-level ab initio calculations of the electronic structure of LiI and simulations of the wave packet dynamics, the exponential signal decay is found to result from predissociation predominantly at the lowest avoided X-A potential curve crossing, for which we infer a coupling constant V{sub XA} = 650(20) cm{sup ?1}. The lack of a pump-probe delay dependence for the case of LiI embedded in helium nanodroplets indicates fast droplet-induced relaxation of the vibrational excitation.

  5. Dynamic imaging with electron microscopy

    ScienceCinema (OSTI)

    Campbell, Geoffrey; McKeown, Joe; Santala, Melissa

    2014-05-30

    Livermore researchers have perfected an electron microscope to study fast-evolving material processes and chemical reactions. By applying engineering, microscopy, and laser expertise to the decades-old technology of electron microscopy, the dynamic transmission electron microscope (DTEM) team has developed a technique that can capture images of phenomena that are both very small and very fast. DTEM uses a precisely timed laser pulse to achieve a short but intense electron beam for imaging. When synchronized with a dynamic event in the microscope's field of view, DTEM allows scientists to record and measure material changes in action. A new movie-mode capability, which earned a 2013 R&D 100 Award from R&D Magazine, uses up to nine laser pulses to sequentially capture fast, irreversible, even one-of-a-kind material changes at the nanometer scale. DTEM projects are advancing basic and applied materials research, including such areas as nanostructure growth, phase transformations, and chemical reactions.

  6. Los Alamos Dynamics Summer School Projects

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Los Alamos Dynamics Summer School » Los Alamos Dynamics Summer School-Overview Los Alamos Dynamics Summer School Projects Los Alamos Dynamics Summer School Projects and Resources Contact Institute Director Charles Farrar (505) 665-0860 Email Executive Administrator Ellie Vigil (505) 667-2818 Email Administrative Assistant Rebecca Duran (505) 665-8899 Email Past Programs and Resources 2015 2014 STUDENT RESOURCES Precollege Undergrads Graduates Postdocs Housing Los Alamos National Laboratory Logo

  7. Dynamic load balancing of applications

    DOE Patents [OSTI]

    Wheat, Stephen R. (Albuquerque, NM)

    1997-01-01

    An application-level method for dynamically maintaining global load balance on a parallel computer, particularly on massively parallel MIMD computers. Global load balancing is achieved by overlapping neighborhoods of processors, where each neighborhood performs local load balancing. The method supports a large class of finite element and finite difference based applications and provides an automatic element management system to which applications are easily integrated.

  8. Dynamic load balancing of applications

    DOE Patents [OSTI]

    Wheat, S.R.

    1997-05-13

    An application-level method for dynamically maintaining global load balance on a parallel computer, particularly on massively parallel MIMD computers is disclosed. Global load balancing is achieved by overlapping neighborhoods of processors, where each neighborhood performs local load balancing. The method supports a large class of finite element and finite difference based applications and provides an automatic element management system to which applications are easily integrated. 13 figs.

  9. Sierra Structural Dynamics User's Notes

    SciTech Connect (OSTI)

    Reese, Garth M.

    2015-10-19

    Sierra/SD provides a massively parallel implementation of structural dynamics finite element analysis, required for high fidelity, validated models used in modal, vibration, static and shock analysis of weapons systems. This document provides a users guide to the input for Sierra/SD. Details of input specifications for the different solution types, output options, element types and parameters are included. The appendices contain detailed examples, and instructions for running the software on parallel platforms.

  10. Simulation and sequential dynamical systems

    SciTech Connect (OSTI)

    Mortveit, H.S.; Reidys, C.M.

    1999-06-01

    Computer simulations have a generic structure. Motivated by this the authors present a new class of discrete dynamical systems that captures this structure in a mathematically precise way. This class of systems consists of (1) a loopfree graph {Upsilon} with vertex set {l_brace}1,2,{hor_ellipsis},n{r_brace} where each vertex has a binary state, (2) a vertex labeled set of functions (F{sub i,{Upsilon}}:F{sub 2}{sup n} {yields} F{sub 2}{sup n}){sub i} and (3) a permutation {pi} {element_of} S{sub n}. The function F{sub i,{Upsilon}} updates the state of vertex i as a function of the states of vertex i and its {Upsilon}-neighbors and leaves the states of all other vertices fixed. The permutation {pi} represents the update ordering, i.e., the order in which the functions F{sub i,{Upsilon}} are applied. By composing the functions F{sub i,{Upsilon}} in the order given by {pi} one obtains the dynamical system (equation given in paper), which the authors refer to as a sequential dynamical system, or SDS for short. The authors will present bounds for the number of functionally different systems and for the number of nonisomorphic digraphs {Gamma}[F{sub {Upsilon}},{pi}] that can be obtained by varying the update order and applications of these to specific graphs and graph classes.

  11. Earth materials and earth dynamics

    SciTech Connect (OSTI)

    Bennett, K; Shankland, T.

    2000-11-01

    In the project ''Earth Materials and Earth Dynamics'' we linked fundamental and exploratory, experimental, theoretical, and computational research programs to shed light on the current and past states of the dynamic Earth. Our objective was to combine different geological, geochemical, geophysical, and materials science analyses with numerical techniques to illuminate active processes in the Earth. These processes include fluid-rock interactions that form and modify the lithosphere, non-linear wave attenuations in rocks that drive plate tectonics and perturb the earth's surface, dynamic recrystallization of olivine that deforms the upper mantle, development of texture in high-pressure olivine polymorphs that create anisotropic velocity regions in the convecting upper mantle and transition zone, and the intense chemical reactions between the mantle and core. We measured physical properties such as texture and nonlinear elasticity, equation of states at simultaneous pressures and temperatures, magnetic spins and bonding, chemical permeability, and thermal-chemical feedback to better characterize earth materials. We artificially generated seismic waves, numerically modeled fluid flow and transport in rock systems and modified polycrystal plasticity theory to interpret measured physical properties and integrate them into our understanding of the Earth. This is the final report of a three-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL).

  12. Brownian dynamics without Green's functions

    SciTech Connect (OSTI)

    Delong, Steven; Donev, Aleksandar; Usabiaga, Florencio Balboa; Delgado-Buscalioni, Rafael; Griffith, Boyce E.; Leon H. Charney Division of Cardiology, Department of Medicine, New York University School of Medicine, New York, New York 10016

    2014-04-07

    We develop a Fluctuating Immersed Boundary (FIB) method for performing Brownian dynamics simulations of confined particle suspensions. Unlike traditional methods which employ analytical Green's functions for Stokes flow in the confined geometry, the FIB method uses a fluctuating finite-volume Stokes solver to generate the action of the response functions on the fly. Importantly, we demonstrate that both the deterministic terms necessary to capture the hydrodynamic interactions among the suspended particles, as well as the stochastic terms necessary to generate the hydrodynamically correlated Brownian motion, can be generated by solving the steady Stokes equations numerically only once per time step. This is accomplished by including a stochastic contribution to the stress tensor in the fluid equations consistent with fluctuating hydrodynamics. We develop novel temporal integrators that account for the multiplicative nature of the noise in the equations of Brownian dynamics and the strong dependence of the mobility on the configuration for confined systems. Notably, we propose a random finite difference approach to approximating the stochastic drift proportional to the divergence of the configuration-dependent mobility matrix. Through comparisons with analytical and existing computational results, we numerically demonstrate the ability of the FIB method to accurately capture both the static (equilibrium) and dynamic properties of interacting particles in flow.

  13. Sandia Energy - Atomistic Molecular Dynamics of Ion-Containing...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Atomistic Molecular Dynamics of Ion-Containing Polymers Home Highlights - HPC Atomistic Molecular Dynamics of Ion-Containing Polymers Previous Next Atomistic Molecular Dynamics of...

  14. Dynamics of micelle-nanoparticle systems undergoing shear: a...

    Office of Scientific and Technical Information (OSTI)

    Dynamics of micelle-nanoparticle systems undergoing shear: a coarse-grained molecular dynamics approach Citation Details In-Document Search Title: Dynamics of micelle-nanoparticle ...

  15. Brownian Dynamics Simulation of Protein Solutions: Structural and Dynamical Properties

    SciTech Connect (OSTI)

    Mereghetti, Paolo; Gabdoulline, Razif; Wade, Rebecca C.

    2010-12-01

    The study of solutions of biomacromolecules provides an important basis for understanding the behavior of many fundamental cellular processes, such as protein folding, self-assembly, biochemical reactions, and signal transduction. Here, we describe a Brownian dynamics simulation procedure and its validation for the study of the dynamic and structural properties of protein solutions. In the model used, the proteins are treated as atomically detailed rigid bodies moving in a continuum solvent. The protein-protein interaction forces are described by the sum of electrostatic interaction, electrostatic desolvation, nonpolar desolvation, and soft-core repulsion terms. The linearized Poisson-Boltzmann equation is solved to compute electrostatic terms. Simulations of homogeneous solutions of three different proteins with varying concentrations, pH, and ionic strength were performed. The results were compared to experimental data and theoretical values in terms of long-time self-diffusion coefficients, second virial coefficients, and structure factors. The results agree with the experimental trends and, in many cases, experimental values are reproduced quantitatively. There are no parameters specific to certain protein types in the interaction model, and hence the model should be applicable to the simulation of the behavior of mixtures of macromolecules in cell-like crowded environments.

  16. Proceedings of the Seventeenth DOE Solar Photochemistry Research Conference

    SciTech Connect (OSTI)

    Not Available

    1993-12-31

    The Seventeenth DOE Solar Photochemistry Research Conference sponsored by the Division of Chemical Sciences, Office of Basic Energy Sciences, is being held June 6--10, 1993, at Cragun`s Lodge and Conference Center, Brainerd, Minnesota The meeting is hosted this year by the Ames Laboratory of Iowa State University. The purpose of the meeting is to foster cooperation, collaboration, and exchange of current research ideas among grantees and contractors of the DOE Division of Chemical Sciences engaged in fundamental research on solar photochemical energy conversion. This conference provides a special opportunity for interaction among investigators from diverse traditional chemistry disciplines who share the common good of providing the knowledge and concepts needed for production of low cost fuels and chemicals or electricity by photochemical conversion of solar energy. Our special guest plenary lecturer is Professor Graham Fleming, of the University of Chicago, who will speak on ultrafast spectroscopic studies of molecular dynamics in the condensed phase. The remaining presentations on Monday will feature further investigations of ultrafast phenomena in solvation, electron transfer, and charge separation at interfaces. These will lead into the topical sessions which follow on photosynthesis, molecular models, photoinduced charge transfer in homogeneous and heterogeneous solutions, inorganic photochemistry, and photoelectrochemistry. As an added feature, the photoelectrochemistry session will include six short introductory lectures for the benefit of nonspecialists on outstanding issues and problems in that field. In this volume may be found a copy of the program, the abstracts of 28 formal presentations and 59 posters, as well as an address listing of the 114 participants.

  17. dynamic-origin-destination-matrix

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Dynamic Origin-Destination Matrix Estimation in TRANSIMS Using Direction-Guided Parallel Heuristic Search Algorithms Adel W. Sadek, Ph.D. Associate Professor University at Buffalo, The State University of New York 233 Ketter Hall Buffalo, NY 14260 Phone: (716) 645-4367 FAX: (716) 645-3733 E-mail: This email address is being protected from spambots. You need JavaScript enabled to view it. List of Authors ================ Adel W. Sadek, Ph.D. Shan Huang Liya Guo University at Buffalo, The State

  18. Interference of probabilities in dynamics

    SciTech Connect (OSTI)

    Zak, Michail

    2014-08-15

    A new class of dynamical systems with a preset type of interference of probabilities is introduced. It is obtained from the extension of the Madelung equation by replacing the quantum potential with a specially selected feedback from the Liouville equation. It has been proved that these systems are different from both Newtonian and quantum systems, but they can be useful for modeling spontaneous collective novelty phenomena when emerging outputs are qualitatively different from the weighted sum of individual inputs. Formation of language and fast decision-making process as potential applications of the probability interference is discussed.

  19. Dynamics of gauge field inflation

    SciTech Connect (OSTI)

    Alexander, Stephon; Jyoti, Dhrubo; Kosowsky, Arthur; Marcianò, Antonino

    2015-05-05

    We analyze the existence and stability of dynamical attractor solutions for cosmological inflation driven by the coupling between fermions and a gauge field. Assuming a spatially homogeneous and isotropic gauge field and fermion current, the interacting fermion equation of motion reduces to that of a free fermion up to a phase shift. Consistency of the model is ensured via the Stückelberg mechanism. We prove the existence of exactly one stable solution, and demonstrate the stability numerically. Inflation arises without fine tuning, and does not require postulating any effective potential or non-standard coupling.

  20. Lagrangian continuum dynamics in ALEGRA.

    SciTech Connect (OSTI)

    Wong, Michael K. W.; Love, Edward

    2007-12-01

    Alegra is an ALE (Arbitrary Lagrangian-Eulerian) multi-material finite element code that emphasizes large deformations and strong shock physics. The Lagrangian continuum dynamics package in Alegra uses a Galerkin finite element spatial discretization and an explicit central-difference stepping method in time. The goal of this report is to describe in detail the characteristics of this algorithm, including the conservation and stability properties. The details provided should help both researchers and analysts understand the underlying theory and numerical implementation of the Alegra continuum hydrodynamics algorithm.

  1. Dynamically Responsive Infrared Window Coatings

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Dynamically Responsive Infrared Window Coatings 2015 Building Technologies Office Peer Review Dr. Kyle J. Alvine, kyle.alvine@pnnl.gov Pacific Northwest National Laboratory 21ºC 50 μm Project Summary Timeline: Start date: 10/1/2013 Planned end date: 6/31/16 Key Milestones 1. (6/30/15) Demonstrate reversible buckling within a temperature window target of 30 C to 90 C over 5-10 cycles (buckle/unbuckle) on a 6" scale - completed February 2015 2. (8/15/15) PPG will complete initial

  2. Dynamic Underground Stripping Demonstration Project

    SciTech Connect (OSTI)

    Aines, R.; Newmark, R.; McConachie, W.; Rice, D.; Ramirez, A.; Siegel, W.; Buettner, M.; Daily, W.; Krauter, P.; Folsom, E.; Boegel, A.J.; Bishop, D. ); udel, K. . Dept. of Mechanical Engineering)

    1992-03-01

    LLNL is collaborating with the UC Berkeley College of Engineering to develop and demonstrate a system of thermal remediation and underground imaging techniques for use in rapid cleanup of localized underground spills. Called Dynamic Stripping'' to reflect the rapid and controllable nature of the process, it will combine steam injection, direct electrical heating, and tomographic geophysical imaging in a cleanup of the LLNL gasoline spill. In the first 8 months of the project, a Clean Site engineering test was conducted to prove the field application of the techniques before moving to the contaminated site in FY 92.

  3. Liquid Dynamics from Neutron Spectrometry

    DOE R&D Accomplishments [OSTI]

    Brockhouse, Bertram N.; Bergsma, J.; Dasannacharya, B. A.; Pope, N. K.

    1962-10-01

    Recent experiments carried out at Chalk River on the dynamics of liquids using neutron inelastic scattering are reviewed, including one by Sakamoto et al., in which the Van Hove self-correlation functions in water at 25 and 75 deg C were determined, and another in which the correlation functions in liquid argon near its triple point were studied. The possible occurrence of short wavelength phonons in classical liquids is discussed, in analogy with their existence in the quantum liquid He4, and in connection with incomplete experiments on liquid tin. (auth)

  4. PyMPI Dynamic Benchmark

    Energy Science and Technology Software Center (OSTI)

    2007-02-16

    Pynamic is a benchmark designed to test a system's ability to handle the Dynamic Linking and Loading (DLL) requirements of Python-based scientific applications. This benchmark is developed to add a workload to our testing environment, a workload that represents a newly emerging class of DLL behaviors. Pynamic buildins on pyMPI, and MPI extension to Python C-extension dummy codes and a glue layer that facilitates linking and loading of the generated dynamic modules into the resultingmore » pyMPI. Pynamic is configurable, enabling modeling the static properties of a specific code as described in section 5. It does not, however, model any significant computationss of the target and hence, it is not subjected to the same level of control as the target code. In fact, HPC computer vendors and tool developers will be encouraged to add it to their tesitn suite once the code release is completed. an ability to produce and run this benchmark is an effective test for valifating the capability of a compiler and linker/loader as well as an OS kernel and other runtime system of HPC computer vendors. In addition, the benchmark is designed as a test case for stressing code development tools. Though Python has recently gained popularity in the HPC community, it heavy DLL operations have hindered certain HPC code development tools, notably parallel debuggers, from performing optimally.« less

  5. Shock dynamics of phase diagrams

    SciTech Connect (OSTI)

    Moro, Antonio

    2014-04-15

    A thermodynamic phase transition denotes a drastic change of state of a physical system due to a continuous change of thermodynamic variables, as for instance pressure and temperature. The classical van der Waals equation of state is the simplest model that predicts the occurrence of a critical point associated with the gasliquid phase transition. Nevertheless, below the critical temperature theoretical predictions of the van der Waals theory significantly depart from the observed physical behaviour. We develop a novel approach to classical thermodynamics based on the solution of Maxwell relations for a generalised family of nonlocal entropy functions. This theory provides an exact mathematical description of discontinuities of the order parameter within the phase transition region, it explains the universal form of the equations of state and the occurrence of triple points in terms of the dynamics of nonlinear shock wave fronts. -- Highlights: A new generalisation of van der Waals equation of state. Description of phase transitions in terms of shock dynamics of state curves. Proof of the universality of equations of state for a general class of models. Interpretation of triple points as confluence of classical shock waves. Correspondence table between thermodynamics and nonlinear conservation laws.

  6. Dynamic Testing of Gasifier Refractory

    SciTech Connect (OSTI)

    Michael D. Mann; Devdutt Shukla; John P. Hurley

    2003-09-27

    The University of North Dakota (UND) Chemical Engineering Department in conjunction with the UND Energy & Environmental Research Center (EERC) have initiated a program to thoroughly examine the combined chemical (reaction and phase change) and physical (erosion) effects experienced by a variety of refractory materials during both normal operation and thermal cycling under slagging coal gasification conditions. The goal of this work is to devise a mechanism of refractory loss under these conditions. The controlled-atmospheric dynamic corrodent application furnace (CADCAF) is being utilized to simulate refractory/slag interactions under dynamic conditions that more realistically simulate the environment in a slagging coal gasifier than any of the static tests used previously by refractory manufacturers and researchers. Shakedown testing of the CADCAF is in progress. Samples of slag and refractory from the Tampa Electric Polk Power Station have been obtained for testing in the CADCAF. The slag has been dried and sieved to the size needed for our flowing slag corrosion tests. Testing is expected to begin in October.

  7. Dynamic Testing of Gasifier Refractory

    SciTech Connect (OSTI)

    Michael D. Mann; Devdutt Shukla; Xi Hong; John P. Hurley

    2004-09-27

    The University of North Dakota (UND) Chemical Engineering Department in conjunction with the UND Energy & Environmental Research Center (EERC) have initiated a program to thoroughly examine the combined chemical (reaction and phase change) and physical (erosion) effects experienced by a variety of refractory materials during both normal operation and thermal cycling under slagging coal gasification conditions. The goal of this work is to devise a mechanism of refractory loss under these conditions. The controlled-atmospheric dynamic corrodent application furnace (CADCAF) is being utilized to simulate refractory/slag interactions under dynamic conditions that more realistically simulate the environment in a slagging coal gasifier than any of the static tests used previously by refractory manufacturers and researchers. Shakedown testing of the CADCAF has been completed. Samples of slag and refractory from the Tampa Electric Polk Power Station have been obtained for testing in the CADCAF. The slag has been dried and sieved to the size needed for our flowing slag corrosion tests. Screening tests are in currently in progress. Detailed analysis of corrosion rates from the first tests is in progress.

  8. Ultrafast electron diffraction from aligned molecules

    SciTech Connect (OSTI)

    Centurion, Martin

    2015-08-17

    The aim of this project was to record time-resolved electron diffraction patterns of aligned molecules and to reconstruct the 3D molecular structure. The molecules are aligned non-adiabatically using a femtosecond laser pulse. A femtosecond electron pulse then records a diffraction pattern while the molecules are aligned. The diffraction patterns are then be processed to obtain the molecular structure.

  9. Ultrafast photodetectors allow direct observation of multiple...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    N.M., Sept. 11, 2015-One of the big benefits of the tiny semiconductor pieces known as quantum dots is that they can crank out multiple electrons from a single photon, a feature...

  10. Ultrafast laser diagnostics to investigate initiation fundamentals...

    Office of Scientific and Technical Information (OSTI)

    be discussed. We have also demonstrated laser shock and particle velocity measurements in thin film explosives using stretched femtosecond laser pulses. We will discuss preliminary...

  11. Ultrafast laser diagnostics to investigate initiation fundamentals...

    Office of Scientific and Technical Information (OSTI)

    pressure and chemical change during the shock initiation of energetic materials. ... We have also demonstrated laser shock and particle velocity measurements in thin film ...

  12. Ultrafast Spectroscopy of Warm Dense Matter

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    the properties of all. In disciplines such as condensed matter or plasma physics, one force often dominates over the others, allowing smaller forces to be neglected in physical...

  13. Ultrafast Spectroscopy of Warm Dense Matter

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Spectroscopy of Warm Dense Matter Print Being neither solid, liquid, gas, nor plasma, warm dense matter (WDM) occupies a no man's land in the map of material phases. Its temperature can range between that of planetary cores (tens of thousands K) to that of stellar cores (hundreds of thousands K). Not only is it prevalent throughout the universe, it is relevant to inertial confinement fusion (ICF) and material performance under extreme conditions. However, because of its extreme temperatures and

  14. Ultrafast Spectroscopy of Warm Dense Matter

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Spectroscopy of Warm Dense Matter Print Being neither solid, liquid, gas, nor plasma, warm dense matter (WDM) occupies a no man's land in the map of material phases. Its...

  15. Electronic Coupling Dependence of Ultrafast Interfacial Electron...

    Office of Scientific and Technical Information (OSTI)

    based devices, including photocatalytic waste degradation and dye sensitized solar cells. ... Sponsoring Org: USDOE; USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22) ...

  16. Electronic Coupling Dependence of Ultrafast Interfacial Electron...

    Office of Scientific and Technical Information (OSTI)

    Electron Transfer on Nanocrystalline Thin Films and Single Crystal Lian, Tianquan 14 SOLAR ENERGY The long-term goal of the proposed research is to understand electron transfer...

  17. Ames Lab 101: Ultrafast Magnetic Switching

    ScienceCinema (OSTI)

    Jigang Wang

    2013-06-05

    Ames Laboratory physicists have found a new way to switch magnetism that is at least 1000 times faster than currently used in magnetic memory technologies. Magnetic switching is used to encode information in hard drives, magnetic random access memory and other computing devices. The discovery potentially opens the door to terahertz and faster memory speeds.

  18. Ultrafast Spectroscopy of Warm Dense Matter

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    a way to freeze and capture such data in the split second before a laser-heated copper sample is destroyed. Our full understanding of planet formation and structures as well...

  19. Electronic Coupling Dependence of Ultrafast Interfacial Electron...

    Office of Scientific and Technical Information (OSTI)

    Sponsoring Org: USDOE; USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22) Country of Publication: United States Language: English Subject: 14 SOLAR ENERGY Word Cloud ...

  20. Ultrafast Spectroscopy of Warm Dense Matter

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    can hardly be ignored. Clearly the theoretical modeling in this case is not straightforward. It is also a regime where good experimental data are in short supply. In this...

  1. Predictive Dynamic Security Assessment through Advanced Computing

    SciTech Connect (OSTI)

    Huang, Zhenyu; Diao, Ruisheng; Jin, Shuangshuang; Chen, Yousu

    2014-11-30

    Abstract— Traditional dynamic security assessment is limited by several factors and thus falls short in providing real-time information to be predictive for power system operation. These factors include the steady-state assumption of current operating points, static transfer limits, and low computational speed. This addresses these factors and frames predictive dynamic security assessment. The primary objective of predictive dynamic security assessment is to enhance the functionality and computational process of dynamic security assessment through the use of high-speed phasor measurements and the application of advanced computing technologies for faster-than-real-time simulation. This paper presents algorithms, computing platforms, and simulation frameworks that constitute the predictive dynamic security assessment capability. Examples of phasor application and fast computation for dynamic security assessment are included to demonstrate the feasibility and speed enhancement for real-time applications.

  2. Dynamical analysis of highly excited molecular spectra

    SciTech Connect (OSTI)

    Kellman, M.E.

    1993-12-01

    The goal of this program is new methods for analysis of spectra and dynamics of highly excited vibrational states of molecules. In these systems, strong mode coupling and anharmonicity give rise to complicated classical dynamics, and make the simple normal modes analysis unsatisfactory. New methods of spectral analysis, pattern recognition, and assignment are sought using techniques of nonlinear dynamics including bifurcation theory, phase space classification, and quantization of phase space structures. The emphasis is chaotic systems and systems with many degrees of freedom.

  3. Accelerated Molecular Dynamics Methods | Department of Energy

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Molecular Dynamics Methods Accelerated Molecular Dynamics Methods This presentation on Accelerated Molecular Dynamics Methods was given at the DOE Theory Focus Session on Hydrogen Storage Materials on May 18, 2006. PDF icon storage_theory_session_voter.pdf More Documents & Publications Simulations of Kinetic Events at the Atomic Scale Transportation, Aging and Disposal Canister System Performance Specification: Revision 1 Waste Characterization, Reduction, and Repackaging Facility (WCRRF)

  4. Laser Driven Dynamic Loading of Condensed Matter

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Laser Driven Dynamic Loading of Condensed Matter Laser Driven Dynamic Loading of Condensed Matter Advanced diagnostics of experiments covering many orders of magnitude in strain rate Contact Eric Loomis (505) 665-3196 Email Dynamic materials experiments over a wide range of strain rates are essential to studying constitutive relations (e.g., plasticity), damage (e.g., spall), equations of state, phase transitions and kinetics, and novel materials. The Trident laser facility supplies unique,

  5. Molecular Dynamics Simulation Studies of Electrolytes and

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Electrolyte/Electrode Interfaces | Department of Energy Dynamics Simulation Studies of Electrolytes and Electrolyte/Electrode Interfaces Molecular Dynamics Simulation Studies of Electrolytes and Electrolyte/Electrode Interfaces 2010 DOE Vehicle Technologies and Hydrogen Programs Annual Merit Review and Peer Evaluation Meeting, June 7-11, 2010 -- Washington D.C. PDF icon es058_smith_2010_p.pdf More Documents & Publications Molecular dynamics simulation and ab intio studies of electrolytes

  6. Chiral dynamics and peripheral transverse densities Granados...

    Office of Scientific and Technical Information (OSTI)

    dynamics and peripheral transverse densities Granados, Carlos G. Uppsala University (Sweden); Weiss, Christian JLAB, Newport News, VA (United States) 72 PHYSICS OF ELEMENTARY...

  7. Extrapolating dynamic leidenfrost principles to metallic nanodroplets...

    Office of Scientific and Technical Information (OSTI)

    The work presented here borrows ideas from two seemingly different fields, metallic droplets and water droplets in the dynamic Leidenfrost regime. Despite the differences in the ...

  8. Mountain-induced Dynamics Influence Cloud Phase

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    2010-2011 via coordinated projects targeting clouds, precipitation, and dynamics in the Park Range of Colorado. The National Science Foundation sponsored aircraft measurements as...

  9. Communication: Quantum molecular dynamics simulation of liquid...

    Office of Scientific and Technical Information (OSTI)

    Communication: Quantum molecular dynamics simulation of liquid para-hydrogen by nuclear and electron wave packet approach Citation Details In-Document Search Title: Communication:...

  10. Quantitative Modeling of High Temperature Magnetization Dynamics

    SciTech Connect (OSTI)

    Zhang, Shufeng

    2009-03-01

    Final Technical Report Project title: Quantitative Modeling of High Temperature Magnetization Dynamics DOE/Office of Science Program Manager Contact: Dr. James Davenport

  11. Regional Dynamics Model (REDYN) | Open Energy Information

    Open Energy Info (EERE)

    use the REDYN model to estimate the effects of actions and policies on people and the economy. The REDYN model powers the unique Regional Dynamics Economic Service, an...

  12. Dynamics of Molecular Clouds: Observations, Simulations, and...

    Office of Scientific and Technical Information (OSTI)

    Simulations, and NIF Experiments Citation Details In-Document Search Title: Dynamics of Molecular Clouds: Observations, Simulations, and NIF Experiments Authors: Kane, J ...

  13. Sierra Structural Dynamics Theory Manual

    SciTech Connect (OSTI)

    Reese, Garth M.

    2015-10-19

    Sierra/SD provides a massively parallel implementation of structural dynamics finite element analysis, required for high fidelity, validated models used in modal, vibration, static and shock analysis of structural systems. This manual describes the theory behind many of the constructs in Sierra/SD. For a more detailed description of how to use Sierra/SD , we refer the reader to Sierra/SD, User's Notes . Many of the constructs in Sierra/SD are pulled directly from published material. Where possible, these materials are referenced herein. However, certain functions in Sierra/SD are specific to our implementation. We try to be far more complete in those areas. The theory manual was developed from several sources including general notes, a programmer notes manual, the user's notes and of course the material in the open literature. This page intentionally left blank.

  14. Dynamic Simulation Nuclear Power Plants

    Energy Science and Technology Software Center (OSTI)

    1992-03-03

    DSNP (Dynamic Simulator for Nuclear Power-Plants) is a system of programs and data files by which a nuclear power plant, or part thereof, can be simulated. The acronym DSNP is used interchangeably for the DSNP language, the DSNP libraries, the DSNP precompiler, and the DSNP document generator. The DSNP language is a special-purpose, block-oriented, digital-simulation language developed to facilitate the preparation of dynamic simulations of a large variety of nuclear power plants. It is amore » user-oriented language that permits the user to prepare simulation programs directly from power plant block diagrams and flow charts by recognizing the symbolic DSNP statements for the appropriate physical components and listing these statements in a logical sequence according to the flow of physical properties in the simulated power plant. Physical components of nuclear power plants are represented by functional blocks, or modules. Many of the more complex components are represented by several modules. The nuclear reactor, for example, has a kinetic module, a power distribution module, a feedback module, a thermodynamic module, a hydraulic module, and a radioactive heat decay module. These modules are stored in DSNP libraries in the form of a DSNP subroutine or function, a block of statements, a macro, or a combination of the above. Basic functional blocks such as integrators, pipes, function generators, connectors, and many auxiliary functions representing properties of materials used in nuclear power plants are also available. The DSNP precompiler analyzes the DSNP simulation program, performs the appropriate translations, inserts the requested modules from the library, links these modules together, searches necessary data files, and produces a simulation program in FORTRAN.« less

  15. Dynamic defense workshop : from research to practice.

    SciTech Connect (OSTI)

    Crosby, Sean Michael; Doak, Justin E.; Haas, Jason J.; Helinski, Ryan; Lamb, Christopher C.

    2013-02-01

    On September 5th and 6th, 2012, the Dynamic Defense Workshop: From Research to Practice brought together researchers from academia, industry, and Sandia with the goals of increasing collaboration between Sandia National Laboratories and external organizations, de ning and un- derstanding dynamic, or moving target, defense concepts and directions, and gaining a greater understanding of the state of the art for dynamic defense. Through the workshop, we broadened and re ned our de nition and understanding, identi ed new approaches to inherent challenges, and de ned principles of dynamic defense. Half of the workshop was devoted to presentations of current state-of-the-art work. Presentation topics included areas such as the failure of current defenses, threats, techniques, goals of dynamic defense, theory, foundations of dynamic defense, future directions and open research questions related to dynamic defense. The remainder of the workshop was discussion, which was broken down into sessions on de ning challenges, applications to host or mobile environments, applications to enterprise network environments, exploring research and operational taxonomies, and determining how to apply scienti c rigor to and investigating the eld of dynamic defense.

  16. Dynamics of polydots: Soft luminescent polymeric nanoparticles

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Maskey, Sabina; Osti, Naresh C.; Grest, Gary S.; Perahia, Dvora

    2016-03-04

    The conformation and dynamics of luminescent polymers collapsed into nanoparticles or polydots were studied using fully atomistic molecular dynamics (MD) simulations, providing a first insight into their internal dynamics. Controlling the conformation and dynamics of confined polymers is essential for realization of the full potential of polydots in nanomedicine and biotechnology. Specifically, the shape and internal dynamics of polydots that consist of highly rigid dialkyl p-phenylene ethynylene (PPE) are probed as a function of temperature. At room temperature, the polydots are spherical without any correlations between the aromatic rings on the PPE backbone. With increasing temperature, they expand and becomemore » slightly aspherical; however, the polymers remain confined. The coherent dynamic structure factor reveals that the internal motion of the polymer backbone is arrested, and the side chains dominate the internal dynamics of the polydots. Lastly, these new soft nanoparticles retain their overall shape and dynamics over an extended temperature range, and their conformation is tunable via their degree of expansion.« less

  17. Dynamic underground stripping demonstration project

    SciTech Connect (OSTI)

    Newmark, R.L.

    1992-04-01

    LLNL is collaborating with the UC Berkeley College of Engineering to develop and demonstrate a system of thermal remediation techniques for rapid cleanup of localized underground spills. Called dynamic stripping to reflect the rapid and controllable nature of the process, it will combine steam injection, direct electrical heating, and tomographic geophysical imaging in a cleanup of the LLNL gasoline spill. In the first eight months of the project, a Clean Site engineering test was conducted to prove the field application of the techniques. Tests then began on the contaminated site in FY 1992. This report describes the work at the Clean Site, including design and performance criteria, test results, interpretations, and conclusions. We fielded 'a wide range of new designs and techniques, some successful and some not. In this document, we focus on results and performance, lessons learned, and design and operational changes recommended for work at the contaminated site. Each section focuses on a different aspect of the work and can be considered a self-contained contribution.

  18. Capturing Dynamics in the Power Grid: Formulation of Dynamic State Estimation through Data Assimilation

    SciTech Connect (OSTI)

    Zhou, Ning; Huang, Zhenyu; Meng, Da; Elbert, Stephen T.; Wang, Shaobu; Diao, Ruisheng

    2014-03-31

    With the increasing complexity resulting from uncertainties and stochastic variations introduced by intermittent renewable energy sources, responsive loads, mobile consumption of plug-in vehicles, and new market designs, more and more dynamic behaviors are observed in everyday power system operation. To operate a power system efficiently and reliably, it is critical to adopt a dynamic paradigm so that effective control actions can be taken in time. The dynamic paradigm needs to include three fundamental components: dynamic state estimation; look-ahead dynamic simulation; and dynamic contingency analysis (Figure 1). These three components answer three basic questions: where the system is; where the system is going; and how secure the system is against accidents. The dynamic state estimation provides a solid cornerstone to support the other 2 components and is the focus of this study.

  19. Parallel Implementation of Power System Dynamic Simulation

    SciTech Connect (OSTI)

    Jin, Shuangshuang; Huang, Zhenyu; Diao, Ruisheng; Wu, Di; Chen, Yousu

    2013-07-21

    Dynamic simulation of power system transient stability is important for planning, monitoring, operation, and control of electrical power systems. However, modeling the system dynamics and network involves the computationally intensive time-domain solution of numerous differential and algebraic equations (DAE). This results in a transient stability implementation that may not maintain the real-time constraints of an online security assessment. This paper presents a parallel implementation of the dynamic simulation on a high-performance computing (HPC) platform using parallel simulation algorithms and computation architectures. It enables the simulation to run even faster than real time, enabling the look-ahead capability of upcoming stability problems in the power grid.

  20. SIAM conference on applications of dynamical systems

    SciTech Connect (OSTI)

    Not Available

    1992-01-01

    A conference (Oct.15--19, 1992, Snowbird, Utah; sponsored by SIAM (Society for Industrial and Applied Mathematics) Activity Group on Dynamical Systems) was held that highlighted recent developments in applied dynamical systems. The main lectures and minisymposia covered theory about chaotic motion, applications in high energy physics and heart fibrillations, turbulent motion, Henon map and attractor, integrable problems in classical physics, pattern formation in chemical reactions, etc. The conference fostered an exchange between mathematicians working on theoretical issues of modern dynamical systems and applied scientists. This two-part document contains abstracts, conference program, and an author index.

  1. Dynamics Modelling of Biolistic Gene Guns

    SciTech Connect (OSTI)

    Zhang, M.; Tao, W.; Pianetta, P.A.

    2009-06-04

    The gene transfer process using biolistic gene guns is a highly dynamic process. To achieve good performance, the process needs to be well understood and controlled. Unfortunately, no dynamic model is available in the open literature for analysing and controlling the process. This paper proposes such a model. Relationships of the penetration depth with the helium pressure, the penetration depth with the acceleration distance, and the penetration depth with the micro-carrier radius are presented. Simulations have also been conducted. The results agree well with experimental results in the open literature. The contribution of this paper includes a dynamic model for improving and manipulating performance of the biolistic gene gun.

  2. TRACKING CODE DEVELOPMENT FOR BEAM DYNAMICS OPTIMIZATION

    SciTech Connect (OSTI)

    Yang, L.

    2011-03-28

    Dynamic aperture (DA) optimization with direct particle tracking is a straight forward approach when the computing power is permitted. It can have various realistic errors included and is more close than theoretical estimations. In this approach, a fast and parallel tracking code could be very helpful. In this presentation, we describe an implementation of storage ring particle tracking code TESLA for beam dynamics optimization. It supports MPI based parallel computing and is robust as DA calculation engine. This code has been used in the NSLS-II dynamics optimizations and obtained promising performance.

  3. Monitoring EGS Stimulation and Reservoir Dynamics with InSAR...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    EGS Stimulation and Reservoir Dynamics with InSAR and MEQ Monitoring EGS Stimulation and Reservoir Dynamics with InSAR and MEQ Monitoring EGS Stimulation and Reservoir Dynamics ...

  4. Nonequilibrium Molecular Dynamics Simulations of the Rheology...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Classical Molecular Dynamics Codes and Coupling of Length Scales Peter T. Cummings 1,2 , Normand Modine 3 and Randy Cygan 4 1 Chemical and Biomolecular Engineering, Vanderbilt U. 2...

  5. Slow Dynamics of Orbital Domains in Manganite

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Slow Dynamics of Orbital Domains in Manganite Print At the ALS, an international team of researchers has used low-energy coherent x rays to extract new knowledge about the...

  6. Single ion dynamics in molten sodium bromide

    SciTech Connect (OSTI)

    Alcaraz, O.; Trullas, J.; Demmel, F.

    2014-12-28

    We present a study on the single ion dynamics in the molten alkali halide NaBr. Quasielastic neutron scattering was employed to extract the self-diffusion coefficient of the sodium ions at three temperatures. Molecular dynamics simulations using rigid and polarizable ion models have been performed in parallel to extract the sodium and bromide single dynamics and ionic conductivities. Two methods have been employed to derive the ion diffusion, calculating the mean squared displacements and the velocity autocorrelation functions, as well as analysing the increase of the line widths of the self-dynamic structure factors. The sodium diffusion coefficients show a remarkable good agreement between experiment and simulation utilising the polarisable potential.

  7. Molecular dynamics simulation studies of electrolytes andelectrolyte...

    Broader source: Energy.gov (indexed) [DOE]

    Review and Peer Evaluation Meeting, May 18-22, 2009 -- Washington D.C. PDF icon es40smith.pdf More Documents & Publications Molecular Dynamics Simulation Studies of Electrolytes ...

  8. Dynamical dipole mode in fusion reactions

    SciTech Connect (OSTI)

    Pierroutsakou, D.; Boiano, A.; Romoli, M.; Martin, B.; Inglima, G.; La Commara, M.; Sandoli, M.; Agodi, C.; Alba, R.; Coniglione, R.; Zoppo, A. Del; Maiolino, C.; Piattelli, P.; Santonocito, D.; Sapienza, P.; Baran, V.; Glodariu, T.; Cardella, G.; De Filippo, E.; Pagano, A.

    2009-05-04

    We investigated the dynamical dipole mode, related with entrance channel charge asymmetry effects, in the {sup 40}Ar+{sup 92}Zr and {sup 36}Ar+{sup 96}Zr fusion reactions at E{sub lab} = 15.1 A and 16 A MeV, respectively. These reactions populate, through entrance channels having different charge asymmetries, a compound nucleus in the A = 126 mass energy region, identical spin distribution at an average excitation energy of about 280 MeV. The compound nucleus average excitation energy and average mass were deduced by the analysis of the light charged particle energy spectra. By studying the {gamma}-ray energy spectra and the {gamma}-ray angular distributions of the considered reactions, the dynamical nature of the prompt radiation related to the dynamical dipole mode was evidenced. The data are compared with calculations based on a collective bremsstrahlung analysis of the reaction dynamics.

  9. Dynamic temperature measurements with embedded optical sensors...

    Office of Scientific and Technical Information (OSTI)

    A variety of static and dynamic measurements were performed to assess re ectance changes at di erent temperatures and pressures. Using a minimal optical model for gold, a plausible ...

  10. Sandia Energy - Molecular Dynamics Simulations Predict Fate of...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Molecular Dynamics Simulations Predict Fate of Uranium in Sediments Home Highlights - Energy Research Molecular Dynamics Simulations Predict Fate of Uranium in Sediments Previous...

  11. Characterization of Dynamic Loads on Solar Modules with Respect...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Characterization of Dynamic Loads on Solar Modules with Respect to Fracture of Solar Cells Characterization of Dynamic Loads on Solar Modules with Respect to Fracture of Solar ...

  12. Interaction and Coalescence of Nanovoids and Dynamic Fracture...

    Office of Scientific and Technical Information (OSTI)

    of Nanovoids and Dynamic Fracture in Silica Glass: Multimiilion-to-Billion Atom Molecular Dynamics Simulations You are accessing a document from the Department of...

  13. O2Diesel Corporation formerly Dynamic Ventures | Open Energy...

    Open Energy Info (EERE)

    O2Diesel Corporation formerly Dynamic Ventures Jump to: navigation, search Name: O2Diesel Corporation (formerly Dynamic Ventures) Place: Newark, Delaware Zip: 19713 Product:...

  14. Jiawei Solarchina Dynamic Green Energy Ltd | Open Energy Information

    Open Energy Info (EERE)

    Jiawei Solarchina Dynamic Green Energy Ltd Jump to: navigation, search Name: Jiawei Solarchina Dynamic Green Energy Ltd Place: Shenzhen, Guangdong Province, China Zip: 518001...

  15. Household Response To Dynamic Pricing Of Electricity: A Survey...

    Open Energy Info (EERE)

    Household Response To Dynamic Pricing Of Electricity: A Survey Of The Experimental Evidence Jump to: navigation, search Tool Summary LAUNCH TOOL Name: Household Response To Dynamic...

  16. ITP Chemicals: Technology Roadmap for Computational Fluid Dynamics...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Fluid Dynamics, January 1999 ITP Chemicals: Technology Roadmap for Computational Fluid Dynamics, January 1999 PDF icon cfdroadmap.pdf More Documents & Publications 3-D Combustion ...

  17. Driven Skyrmions and Dynamical Transitions in Chiral Magnets...

    Office of Scientific and Technical Information (OSTI)

    Driven Skyrmions and Dynamical Transitions in Chiral Magnets Citation Details In-Document Search Title: Driven Skyrmions and Dynamical Transitions in Chiral Magnets Authors: Lin, ...

  18. Dynamic trapping near a quantum critical point (Journal Article...

    Office of Scientific and Technical Information (OSTI)

    Dynamic trapping near a quantum critical point Citation Details In-Document Search Title: Dynamic trapping near a quantum critical point Authors: Kolodrubetz, Michael ; Katz, ...

  19. Multichannel Kondo Impurity Dynamics in a Majorana Device (Journal...

    Office of Scientific and Technical Information (OSTI)

    Multichannel Kondo Impurity Dynamics in a Majorana Device Prev Next Title: Multichannel Kondo Impurity Dynamics in a Majorana Device Authors: Altland, A. ; Bri, B. ; Egger, ...

  20. Optical reflectance as a dynamic temperature diagnostic. (Conference...

    Office of Scientific and Technical Information (OSTI)

    Conference: Optical reflectance as a dynamic temperature diagnostic. Citation Details In-Document Search Title: Optical reflectance as a dynamic temperature diagnostic. Abstract ...

  1. High Temperature Dynamics Strain Hardening Behavior in Stainless...

    Office of Scientific and Technical Information (OSTI)

    High Temperature Dynamics Strain Hardening Behavior in Stainless Steels and Nickel Alloys Citation Details In-Document Search Title: High Temperature Dynamics Strain Hardening ...

  2. HyDIVE (Hydrogen Dynamic Infrastructure and Vehicle Evolution...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    HyDIVE (Hydrogen Dynamic Infrastructure and Vehicle Evolution) Model Analysis HyDIVE (Hydrogen Dynamic Infrastructure and Vehicle Evolution) Model Analysis Presentation by NREL's ...

  3. Computational Fluid Dynamics Modeling of Diesel Engine Combustion...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Computational Fluid Dynamics Modeling of Diesel Engine Combustion and Emissions Computational Fluid Dynamics Modeling of Diesel Engine Combustion and Emissions 2005 Diesel Engine...

  4. Interaction and Coalescence of Nanovoids and Dynamic Fracture...

    Office of Scientific and Technical Information (OSTI)

    of Nanovoids and Dynamic Fracture in Silica Glass: Multimiilion-to-Billion Atom Molecular Dynamics Simulations Citation Details In-Document Search Title: Interaction and...

  5. Online optimization of storage ring nonlinear beam dynamics ...

    Office of Scientific and Technical Information (OSTI)

    Online optimization of storage ring nonlinear beam dynamics Citation Details In-Document Search Title: Online optimization of storage ring nonlinear beam dynamics Authors: Huang,...

  6. Online optimization of storage ring nonlinear beam dynamics ...

    Office of Scientific and Technical Information (OSTI)

    Online optimization of storage ring nonlinear beam dynamics Citation Details In-Document Search Title: Online optimization of storage ring nonlinear beam dynamics You are...

  7. Quantum effects in the dynamics of deeply supercooled water ...

    Office of Scientific and Technical Information (OSTI)

    Quantum effects in the dynamics of deeply supercooled water Citation Details In-Document Search Title: Quantum effects in the dynamics of deeply supercooled water Authors: Agapov, ...

  8. Dynamic Evolution of Cement Composition and Transport Properties...

    Office of Scientific and Technical Information (OSTI)

    Dynamic Evolution of Cement Composition and Transport Properties under Conditions Relevant to Geological Carbon Sequestration Citation Details In-Document Search Title: Dynamic ...

  9. Modeling Dynamic Ductility: An Equation of State for Porous Metals...

    Office of Scientific and Technical Information (OSTI)

    Dynamic Ductility: An Equation of State for Porous Metals Citation Details In-Document Search Title: Modeling Dynamic Ductility: An Equation of State for Porous Metals You are...

  10. A Fast Dynamic Language for Technical Computing Stefan Karpinski...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Fast Dynamic Language for Technical Computing Stefan Karpinski, Jeff Bezanson, Viral B. Shah & Alan Edelman u a l j i Two Language Problem People love dynamic environments for...

  11. DLFM library tools for large scale dynamic applications

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    applications DLFM library tools for large scale dynamic applications Large scale Python and other dynamic applications may spend huge time at startup. The DLFM library,...

  12. Plant Root Characteristics and Dynamics in Arctic Tundra Ecosystems...

    Office of Scientific and Technical Information (OSTI)

    Dataset: Plant Root Characteristics and Dynamics in Arctic Tundra Ecosystems, 1960-2012 Citation Details In-Document Search Title: Plant Root Characteristics and Dynamics in Arctic...

  13. Anomaly Detection in Dynamic Networks

    SciTech Connect (OSTI)

    Turcotte, Melissa

    2014-10-14

    Anomaly detection in dynamic communication networks has many important security applications. These networks can be extremely large and so detecting any changes in their structure can be computationally challenging; hence, computationally fast, parallelisable methods for monitoring the network are paramount. For this reason the methods presented here use independent node and edge based models to detect locally anomalous substructures within communication networks. As a first stage, the aim is to detect changes in the data streams arising from node or edge communications. Throughout the thesis simple, conjugate Bayesian models for counting processes are used to model these data streams. A second stage of analysis can then be performed on a much reduced subset of the network comprising nodes and edges which have been identified as potentially anomalous in the first stage. The first method assumes communications in a network arise from an inhomogeneous Poisson process with piecewise constant intensity. Anomaly detection is then treated as a changepoint problem on the intensities. The changepoint model is extended to incorporate seasonal behavior inherent in communication networks. This seasonal behavior is also viewed as a changepoint problem acting on a piecewise constant Poisson process. In a static time frame, inference is made on this extended model via a Gibbs sampling strategy. In a sequential time frame, where the data arrive as a stream, a novel, fast Sequential Monte Carlo (SMC) algorithm is introduced to sample from the sequence of posterior distributions of the change points over time. A second method is considered for monitoring communications in a large scale computer network. The usage patterns in these types of networks are very bursty in nature and dont fit a Poisson process model. For tractable inference, discrete time models are considered, where the data are aggregated into discrete time periods and probability models are fitted to the communication counts. In a sequential analysis, anomalous behavior is then identified from outlying behavior with respect to the fitted predictive probability models. Seasonality is again incorporated into the model and is treated as a changepoint model on the transition probabilities of a discrete time Markov process. Second stage analytics are then developed which combine anomalous edges to identify anomalous substructures in the network.

  14. Slow Dynamics of Orbital Domains in Manganite

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Slow Dynamics of Orbital Domains in Manganite Slow Dynamics of Orbital Domains in Manganite Print Wednesday, 25 June 2008 00:00 At the ALS, an international team of researchers has used low-energy coherent x rays to extract new knowledge about the correlated motion of groups of self-assembled, outer-lying electrons in the extremely complex electronic system found in manganites. The manganite family of materials has puzzled physicists for years by defying standard models for the motion of

  15. computational-fluid-dynamics-student-thesis

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Fluid Dynamics Student Thesis Abstract DEVELOPMENT OF A THREE-DIMENSIONAL SCOURING METHODOLOGY AND ITS IMPLEMENTATION IN A COMMERCIAL CFD CODE FOR OPEN CHANNEL FLOW OVER A FLOODED BRIDGE DECK The Computational Fluid Dynamics staff at TRACC is supporting three students from Northern Illinois University who are working for a Masters degree. The CFD staff is directing the thesis research and working with them on three projects: (1) a three-dimensional scour computation methodology for pressure flow

  16. Protein Dynamics Hit the Big Screen

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Protein Dynamics Hit the Big Screen Protein Dynamics Hit the Big Screen Now playing at a supercomputer near you: proteins in action June 29, 2005 Contact: Dan Krotz, dakrotz@lbl.gov 06tyrosinekinasechanging.jpg This simulation of a tyrosine kinase reveals how the protein changes shape. Scientists from Berkeley Lab and UC Berkeley are using one the world's most powerful computers to simulate how protein molecules move, rotate, and fold as they carry out life's most fundamental tasks.Although they

  17. Reflectance thermometry in dynamic compression experiments. (Conference) |

    Office of Scientific and Technical Information (OSTI)

    SciTech Connect Reflectance thermometry in dynamic compression experiments. Citation Details In-Document Search Title: Reflectance thermometry in dynamic compression experiments. Abstract not provided. Authors: Dolan, Daniel H., ; Ao, Tommy ; Seagle, Christopher T Publication Date: 2012-02-01 OSTI Identifier: 1118217 Report Number(s): SAND2012-0864C 481321 DOE Contract Number: AC04-94AL85000 Resource Type: Conference Resource Relation: Conference: 9th International Temperature Symposium held

  18. Combined statistical and dynamical assessment of simulated

    Office of Scientific and Technical Information (OSTI)

    vegetation-rainfall in North Africa during the mid-Holocene* (Journal Article) | SciTech Connect Combined statistical and dynamical assessment of simulated vegetation-rainfall in North Africa during the mid-Holocene* Citation Details In-Document Search Title: Combined statistical and dynamical assessment of simulated vegetation-rainfall in North Africa during the mid-Holocene* A negative feedback of vegetation cover on subsequent annual precipitation is simulated for the mid-Holocene over

  19. Molecular dynamics simulation studies of electrolytes and

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    electrolyte/electrode interfaces | Department of Energy studies of electrolytes and electrolyte/electrode interfaces Molecular dynamics simulation studies of electrolytes and electrolyte/electrode interfaces 2009 DOE Hydrogen Program and Vehicle Technologies Program Annual Merit Review and Peer Evaluation Meeting, May 18-22, 2009 -- Washington D.C. PDF icon es_40_smith.pdf More Documents & Publications Molecular Dynamics Simulation Studies of Electrolytes and Electrolyte/Electrode

  20. The Dynamic Analyzer for MPI: the first dynamic analyzer of MPI

    Energy Science and Technology Software Center (OSTI)

    2013-10-31

    DAMPI is a dynamic testing/verification tool that scalably covers non-deterministic interactions of MPI (e.g., sildcard-receives).

  1. Dynamic force matching: A method for constructing dynamical coarse-grained models with realistic time dependence

    SciTech Connect (OSTI)

    Davtyan, Aram; Dama, James F.; Voth, Gregory A.; Andersen, Hans C.

    2015-04-21

    Coarse-grained (CG) models of molecular systems, with fewer mechanical degrees of freedom than an all-atom model, are used extensively in chemical physics. It is generally accepted that a coarse-grained model that accurately describes equilibrium structural properties (as a result of having a well constructed CG potential energy function) does not necessarily exhibit appropriate dynamical behavior when simulated using conservative Hamiltonian dynamics for the CG degrees of freedom on the CG potential energy surface. Attempts to develop accurate CG dynamic models usually focus on replacing Hamiltonian motion by stochastic but Markovian dynamics on that surface, such as Langevin or Brownian dynamics. However, depending on the nature of the system and the extent of the coarse-graining, a Markovian dynamics for the CG degrees of freedom may not be appropriate. In this paper, we consider the problem of constructing dynamic CG models within the context of the Multi-Scale Coarse-graining (MS-CG) method of Voth and coworkers. We propose a method of converting a MS-CG model into a dynamic CG model by adding degrees of freedom to it in the form of a small number of fictitious particles that interact with the CG degrees of freedom in simple ways and that are subject to Langevin forces. The dynamic models are members of a class of nonlinear systems interacting with special heat baths that were studied by Zwanzig [J. Stat. Phys. 9, 215 (1973)]. The properties of the fictitious particles can be inferred from analysis of the dynamics of all-atom simulations of the system of interest. This is analogous to the fact that the MS-CG method generates the CG potential from analysis of equilibrium structures observed in all-atom simulation data. The dynamic models generate a non-Markovian dynamics for the CG degrees of freedom, but they can be easily simulated using standard molecular dynamics programs. We present tests of this method on a series of simple examples that demonstrate that the method provides realistic dynamical CG models that have non-Markovian or close to Markovian behavior that is consistent with the actual dynamical behavior of the all-atom system used to construct the CG model. Both the construction and the simulation of such a dynamic CG model have computational requirements that are similar to those of the corresponding MS-CG model and are good candidates for CG modeling of very large systems.

  2. Dynamic Event Tree Analysis Through RAVEN

    SciTech Connect (OSTI)

    A. Alfonsi; C. Rabiti; D. Mandelli; J. Cogliati; R. A. Kinoshita; A. Naviglio

    2013-09-01

    Conventional Event-Tree (ET) based methodologies are extensively used as tools to perform reliability and safety assessment of complex and critical engineering systems. One of the disadvantages of these methods is that timing/sequencing of events and system dynamics is not explicitly accounted for in the analysis. In order to overcome these limitations several techniques, also know as Dynamic Probabilistic Risk Assessment (D-PRA), have been developed. Monte-Carlo (MC) and Dynamic Event Tree (DET) are two of the most widely used D-PRA methodologies to perform safety assessment of Nuclear Power Plants (NPP). In the past two years, the Idaho National Laboratory (INL) has developed its own tool to perform Dynamic PRA: RAVEN (Reactor Analysis and Virtual control ENvironment). RAVEN has been designed in a high modular and pluggable way in order to enable easy integration of different programming languages (i.e., C++, Python) and coupling with other application including the ones based on the MOOSE framework, developed by INL as well. RAVEN performs two main tasks: 1) control logic driver for the new Thermo-Hydraulic code RELAP-7 and 2) post-processing tool. In the first task, RAVEN acts as a deterministic controller in which the set of control logic laws (user defined) monitors the RELAP-7 simulation and controls the activation of specific systems. Moreover, RAVEN also models stochastic events, such as components failures, and performs uncertainty quantification. Such stochastic modeling is employed by using both MC and DET algorithms. In the second task, RAVEN processes the large amount of data generated by RELAP-7 using data-mining based algorithms. This paper focuses on the first task and shows how it is possible to perform the analysis of dynamic stochastic systems using the newly developed RAVEN DET capability. As an example, the Dynamic PRA analysis, using Dynamic Event Tree, of a simplified pressurized water reactor for a Station Black-Out scenario is presented.

  3. Computational simulation of dynamic impact problems

    SciTech Connect (OSTI)

    Muenz, T.W.; Rix, K.S.; Willam, K.J.

    1996-12-31

    Recent advances of computing methods make it possible to examine dynamic failure and complicated contact-impact load scenarios in time and space. The response simulation for these extreme load conditions needs to capture dynamic contact between the impactor and the deformable target and progressive failure in the target. Independently from the impact scenario, two basic approaches may be used to describe the failure process in an appropriate manner, namely the Discrete Failure Approach and the Smeared Failure Approach. In the contribution the dynamic impact of a pendulum test and the failure scenario in notched cylindrical specimens (Charpy-type IZOD test) are examined using the explicit dynamic finite element code DYNA3D. The study focuses on the question, whether the smeared crack approach is able to capture the dynamic failure process using von Mises plasticity with a plastic strain-based failure limiter. The computational results indicate that upon consistent mesh refinement the overall energy dissipation approaches the value observed in laboratory experiments.

  4. Hydrogen bond dynamics in bulk alcohols

    SciTech Connect (OSTI)

    Shinokita, Keisuke; Cunha, Ana V.; Jansen, Thomas L. C.; Pshenichnikov, Maxim S.

    2015-06-07

    Hydrogen-bonded liquids play a significant role in numerous chemical and biological phenomena. In the past decade, impressive developments in multidimensional vibrational spectroscopy and combined molecular dynamicsquantum mechanical simulation have established many intriguing features of hydrogen bond dynamics in one of the fundamental solvents in nature, water. The next class of a hydrogen-bonded liquidalcoholshas attracted much less attention. This is surprising given such important differences between water and alcohols as the imbalance between the number of hydrogen bonds, each molecule can accept (two) and donate (one) and the very presence of the hydrophobic group in alcohols. Here, we use polarization-resolved pump-probe and 2D infrared spectroscopy supported by extensive theoretical modeling to investigate hydrogen bond dynamics in methanol, ethanol, and isopropanol employing the OH stretching mode as a reporter. The sub-ps dynamics in alcohols are similar to those in water as they are determined by similar librational and hydrogen-bond stretch motions. However, lower density of hydrogen bond acceptors and donors in alcohols leads to the appearance of slow diffusion-controlled hydrogen bond exchange dynamics, which are essentially absent in water. We anticipate that the findings herein would have a potential impact on fundamental chemistry and biology as many processes in nature involve the interplay of hydrophobic and hydrophilic groups.

  5. Element-specific spin and orbital momentum dynamics of Fe/Gdmultilayers

    SciTech Connect (OSTI)

    Bartelt, A.F.; Comin, A.; Feng, J.; Nasiatka, J.R.; Eimuller, T.; Ludescher, B.; Schutz, G.; Padmore, H.A.; Young, A.T.; Scholl, A.

    2007-03-23

    The role of orbital magnetism in the laser-induced demagnetization of Fe/Gd multilayers was investigated using time-resolved X-ray magnetic circular dichroism at 2-ps time resolution given by an x-ray streak camera. An ultrafast transfer of angular momentum from the spin via the orbital momentum to the lattice was observed which was characterized by rapidly thermalizing spin and orbital momenta. Strong interlayer exchange coupling between Fe and Gd led to a simultaneous demagnetization of both layers.

  6. Current scaling of axially radiated power in dynamic hohlraums and dynamic hohlraum load design for ZR.

    SciTech Connect (OSTI)

    Mock, Raymond Cecil; Nash, Thomas J.; Sanford, Thomas W. L.

    2007-03-01

    We present designs for dynamic hohlraum z-pinch loads on the 28 MA, 140 ns driver ZR. The scaling of axially radiated power with current in dynamic hohlraums is reviewed. With adequate stability on ZR this scaling indicates that 30 TW of axially radiated power should be possible. The performance of the dynamic hohlraum load on the 20 MA, 100 ns driver Z is extensively reviewed. The baseline z-pinch load on Z is a nested tungsten wire array imploding onto on-axis foam. Data from a variety of x-ray diagnostics fielded on Z are presented. These diagnostics include x-ray diodes, bolometers, fast x-ray imaging cameras, and crystal spectrometers. Analysis of these data indicates that the peak dynamic radiation temperature on Z is between 250 and 300 eV from a diameter less than 1 mm. Radiation from the dynamic hohlraum itself or from a radiatively driven pellet within the dynamic hohlraum has been used to probe a variety of matter associated with the dynamic hohlraum: the tungsten z-pinch itself, tungsten sliding across the end-on apertures, a titanium foil over the end aperture, and a silicon aerogel end cap. Data showing the existence of asymmetry in radiation emanating from the two ends of the dynamic hohlraum is presented, along with data showing load configurations that mitigate this asymmetry. 1D simulations of the dynamic hohlraum implosion are presented and compared to experimental data. The simulations provide insight into the dynamic hohlraum behavior but are not necessarily a reliable design tool because of the inherently 3D behavior of the imploding nested tungsten wire arrays.

  7. Interaction and Coalescence of Nanovoids and Dynamic Fracture in Silica

    Office of Scientific and Technical Information (OSTI)

    Glass: Multimiilion-to-Billion Atom Molecular Dynamics Simulations (Journal Article) | SciTech Connect Interaction and Coalescence of Nanovoids and Dynamic Fracture in Silica Glass: Multimiilion-to-Billion Atom Molecular Dynamics Simulations Citation Details In-Document Search Title: Interaction and Coalescence of Nanovoids and Dynamic Fracture in Silica Glass: Multimiilion-to-Billion Atom Molecular Dynamics Simulations Authors: Nomura, K ; Chen, Y C ; Kalia, R K ; Nakano, A ; Vashishta, P ;

  8. DLFM library tools for large scale dynamic applications

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    DLFM library tools for large scale dynamic applications DLFM library tools for large scale dynamic applications Large scale Python and other dynamic applications may spend huge time at startup. The DLFM library, developed by Mike Davis at Cray, Inc., is a set of functions that can be incorporated into a dynamically-linked application to provide improved performance during the loading of dynamic libraries when running the application at large scale on Edison. To access this library, do module

  9. A study of the HEB longitudinal dynamics

    SciTech Connect (OSTI)

    Larson, D.J.

    1993-12-01

    A study of the High Energy Booster (HEB) longitudinal dynamics is presented. Full derivations of ramp dependent longitudinal variables are given. The formulas assume that the input magnetic field and beam longitudinal emittance are known as a function of time, and that either the rf voltage or the rf bucket area are known as a function of time. Once these three inputs are specified, the formulas can be used to calculate values for all other longitudinal dynamics variables. The formulas have been incorporated into a single computer code named ELVIRA: Evaluation of Longitudinal Variables in Relativistic Accelerators. The ELVIRA code is documented here in detail. The ELVIRA code is used under two initial longitudinal emittance assumptions to plot ramp functions for the longitudinal dynamics design of the HEB as of May 5, 1992.

  10. Application of optimal prediction to molecular dynamics

    SciTech Connect (OSTI)

    Barber IV, John Letherman

    2004-12-01

    Optimal prediction is a general system reduction technique for large sets of differential equations. In this method, which was devised by Chorin, Hald, Kast, Kupferman, and Levy, a projection operator formalism is used to construct a smaller system of equations governing the dynamics of a subset of the original degrees of freedom. This reduced system consists of an effective Hamiltonian dynamics, augmented by an integral memory term and a random noise term. Molecular dynamics is a method for simulating large systems of interacting fluid particles. In this thesis, I construct a formalism for applying optimal prediction to molecular dynamics, producing reduced systems from which the properties of the original system can be recovered. These reduced systems require significantly less computational time than the original system. I initially consider first-order optimal prediction, in which the memory and noise terms are neglected. I construct a pair approximation to the renormalized potential, and ignore three-particle and higher interactions. This produces a reduced system that correctly reproduces static properties of the original system, such as energy and pressure, at low-to-moderate densities. However, it fails to capture dynamical quantities, such as autocorrelation functions. I next derive a short-memory approximation, in which the memory term is represented as a linear frictional force with configuration-dependent coefficients. This allows the use of a Fokker-Planck equation to show that, in this regime, the noise is {delta}-correlated in time. This linear friction model reproduces not only the static properties of the original system, but also the autocorrelation functions of dynamical variables.

  11. VUV studies of molecular photofragmentation dynamics

    SciTech Connect (OSTI)

    White, M.G.

    1993-12-01

    State-resolved, photoion and photoelectron methods are used to study the neutral fragmentation and ionization dynamics of small molecules relevant to atmospheric and combustion chemistry. Photodissociation and ionization are initiated by coherent VUV radiation and the fragmentation dynamics are extracted from measurements of product rovibronic state distributions, kinetic energies and angular distributions. The general aim of these studies is to investigate the multichannel interactions between the electronic and nuclear motions which determine the evolution of the photoexcited {open_quotes}complex{close_quotes} into the observed asymptotic channels.

  12. Evolution of entanglement under echo dynamics

    SciTech Connect (OSTI)

    Prosen, Tomaz; Znidaric, Marko [Physics Department, FMF, University of Ljubljana, Ljubljana (Slovenia); Seligman, Thomas H. [Centro de Ciencias Fisicas, University of Mexico (UNAM), Cuernavaca (Mexico)

    2003-04-01

    Echo dynamics and fidelity are often used to discuss stability in quantum-information processing and quantum chaos. Yet fidelity yields no information about entanglement, the characteristic property of quantum mechanics. We study the evolution of entanglement in echo dynamics. We find qualitatively different behavior between integrable and chaotic systems on one hand and between random and coherent initial states for integrable systems on the other. For the latter the evolution of entanglement is given by a classical time scale. Analytic results are illustrated numerically in a Jaynes-Cummings model.

  13. Very Large System Dynamics Models - Lessons Learned

    SciTech Connect (OSTI)

    Jacob J. Jacobson; Leonard Malczynski

    2008-10-01

    This paper provides lessons learned from developing several large system dynamics (SD) models. System dynamics modeling practice emphasize the need to keep models small so that they are manageable and understandable. This practice is generally reasonable and prudent; however, there are times that large SD models are necessary. This paper outlines two large SD projects that were done at two Department of Energy National Laboratories, the Idaho National Laboratory and Sandia National Laboratories. This paper summarizes the models and then discusses some of the valuable lessons learned during these two modeling efforts.

  14. Dynamics of capillary condensation in aerogels

    SciTech Connect (OSTI)

    Nomura, R.; Miyashita, W.; Yoneyama, K.; Okuda, Y. [Department of Condensed Matter Physics, Tokyo Institute of Technology, 2-12-1 O-okayama, Meguro, Tokyo 152-8551 (Japan)

    2006-03-15

    Dynamics of capillary condensation of liquid {sup 4}He in various density silica aerogels was investigated systematically. Interfaces were clearly visible when bulk liquid was rapidly sucked into the aerogel. Time evolution of the interface positions was consistent with the Washburn model and their effective pore radii were obtained. Condensation was a single step in a dense aerogel and two steps in a low density aerogel. Crossover between the two types of condensation was observed in an intermediate density aerogel. Variety of the dynamics may be the manifestation of the fractal nature of aerogels which had a wide range of distribution of pore radii.

  15. Dynamic analysis of tension-leg platforms

    SciTech Connect (OSTI)

    Morgan, J.R.

    1983-01-01

    The dynamic response of tension-leg platforms subjected to wave loading was investigated using a deterministic dynamic analysis. The model employed in this study is based on coupled nonlinear stiffness coefficients and closed form inertia and drag forcing functions derived using Morison's equation. The forcing functions include relative motion behavior between the fluid particles and the structure. These forcing functions are integrated manually thereby avoiding the need for expensive numerical integration. A set of coupled nonlinear differential equations was integrated sequentially in the time domain using the Newmark beta-method. A computer program was developed to simulate the time history response of the platform motion.

  16. Laser spectroscopy and dynamics of transient species

    SciTech Connect (OSTI)

    Clouthier, D.J.

    1993-12-01

    The goal of this program is to study the vibrational and electronic spectra and excited state dynamics of a number of transient sulfur and oxygen species. A variety of supersonic jet techniques, as well as high resolution FT-IR and intracavity dye laser spectroscopy, have been applied to these studies.

  17. Order, chaos and nuclear dynamics: An introduction

    SciTech Connect (OSTI)

    Swiatecki, W.J.

    1990-08-01

    This is an introductory lecture illustrating by simple examples the anticipated effect on collective nuclear dynamics of a transition from order to chaos in the motions of nucleons inside an idealized nucleus. The destruction of order is paralleled by a transition from a rubber-like to a honey-like behaviour of the independent-particle nuclear model. 10 refs., 6 figs.

  18. Static & Dynamic Response of 3D Solids

    Energy Science and Technology Software Center (OSTI)

    1996-07-15

    NIKE3D is a large deformations 3D finite element code used to obtain the resulting displacements and stresses from multi-body static and dynamic structural thermo-mechanics problems with sliding interfaces. Many nonlinear and temperature dependent constitutive models are available.

  19. Estimating the uncertainty in underresolved nonlinear dynamics

    SciTech Connect (OSTI)

    Chorin, Alelxandre; Hald, Ole

    2013-06-12

    The Mori-Zwanzig formalism of statistical mechanics is used to estimate the uncertainty caused by underresolution in the solution of a nonlinear dynamical system. A general approach is outlined and applied to a simple example. The noise term that describes the uncertainty turns out to be neither Markovian nor Gaussian. It is argued that this is the general situation.

  20. Notes on beam dynamics in linear accelerators

    SciTech Connect (OSTI)

    Gluckstern, R.L.

    1980-09-01

    A collection of notes, on various aspects of beam dynamics in linear accelerators, which were produced by the author during five years (1975 to 1980) of consultation for the LASL Accelerator Technology (AT) Division and Medium-Energy Physics (MP) Division is presented.