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1

Ultrafast vectorial and scalar dynamics of ionic clusters: Azobenzene solvated by oxygen  

SciTech Connect

The ultrafast dynamics of clusters of trans-azobenzene anion (A{sup -}) solvated by oxygen molecules was investigated using femtosecond time-resolved photoelectron spectroscopy. The time scale for stripping off all oxygen molecules from A{sup -} was determined by monitoring in real time the transient of the A{sup -} rise, following an 800 nm excitation of A{sup -} (O{sub 2}){sub n}, where n=1-4. A careful analysis of the time-dependent photoelectron spectra strongly suggests that for n>1 a quasi-O{sub 4} core is formed and that the dissociation occurs by a bond cleavage between A{sup -} and conglomerated (O{sub 2}){sub n} rather than a stepwise evaporation of O{sub 2}. With time and energy resolutions, we were able to capture the photoelectron signatures of transient species which instantaneously rise (<100 fs) then decay. The transient species are assigned as charge-transfer complexes: A{center_dot}O{sub 2}{sup -} for A{sup -}O{sub 2} and A{center_dot}O{sub 4}{sup -}{center_dot}(O{sub 2}){sub n-2} for A{sup -}(O{sub 2}){sub n}, where n=2-4. Subsequent to an ultrafast electron recombination, A{sup -} rises with two distinct time scales: a subpicosecond component reflecting a direct bond rupture of the A{sup -}-(O{sub 2}){sub n} nuclear coordinate and a slower component (1.6-36 ps, increasing with n) attributed to an indirect channel exhibiting a quasistatistical behavior. The photodetachment transients exhibit a change in the transition dipole direction as a function of time delay. Rotational dephasing occurs on a time scale of 2-3 ps, with a change in the sign of the transient anisotropy between A{sup -}O{sub 2} and the larger clusters. This behavior is a key indicator of an evolving cluster structure and is successfully modeled by calculations based on the structures and inertial motion of the parent clusters.

Paik, D. Hern; Baskin, J. Spencer; Kim, Nam Joon; Zewail, Ahmed H. [Laboratory for Molecular Sciences, California Institute of Technology, Pasadena, California 91125 and Physical Biology Center for Ultrafast Science and Technology, California Institute of Technology, Pasadena, California 91125 (United States)

2006-10-07T23:59:59.000Z

2

Ionic Liquids: Radiation Chemistry, Solvation Dynamics and Reactivity Patterns  

SciTech Connect

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.

Wishart, J.F.

2011-06-12T23:59:59.000Z

3

Solvation!  

SciTech Connect

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.

Ivana Adamovic

2004-12-19T23:59:59.000Z

4

Ultrafast studies of solution dynamics  

SciTech Connect

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.

Woodruff, W.H.; Dyer, R.B. [Los Alamos National Lab., NM (United States); Callender, R.H. [City Univ. of New York, NY (United States). Dept. of Physics

1997-10-01T23:59:59.000Z

5

Intermolecular Dynamics, Interactions and Solvation in Ionic Liquids  

NLE Websites -- All DOE Office Websites (Extended Search)

Dynamics, Interactions and Solvation in Ionic Liquids Dynamics, Interactions and Solvation in Ionic Liquids Edward W. Castner, Jr., James F. Wishart, and Hideaki Shirota Acc. Chem. Res. 40, 1217-1227 (2007). [Find paper at ACS Publications] Abstract: Ionic liquids can simultaneously assume multiple solvent roles, because they are strongly polar and polarizable solvents and binary solutions and frequently contain very hydrophobic components. When the cation and anion functional groups are tuned appropriately, ionic liquids can be used as designer solvents for a broad range of applications. In this Account, we discuss our spectroscopic studies on the intermolecular interactions, dynamics, solvation, transport, and friction in ionic liquids, as compared with information obtained from macroscopic experiments including viscometry

6

Hydroxide Hydrogen Bonding: Probing the Solvation Structure through Ultrafast Time Domain Raman Spectroscopy  

Science Journals Connector (OSTI)

(6-8) It has also been supported by neutron scattering experiments that suggest coordination numbers between 3.5 and 5.(9, 10) In addition, Car–Parrinello molecular dynamics (CPMD) calculations support the hypercoordination picture, suggesting a concentration and counterion-dependent distribution of 3–5 water molecules bonded to the hydroxide oxygen. ... (20, 30) The 15 fs pulses were generated by a Kerr-lens mode-locked Ti:Sapphire laser with center wavelength of 800 nm, an 80 nm bandwidth, and an 800 mW average power. ... energy structure on the potential energy surface, because the water drifts to become attached to one of the first solvation shell waters. ...

Ismael A. Heisler; Kamila Mazur; Stephen R. Meech

2011-04-27T23:59:59.000Z

7

Probing Ultrafast Solvation Dynamics with High Repetition-Rate...  

NLE Websites -- All DOE Office Websites (Extended Search)

systems. Thanks to implementation of a high-repetition-rate (54 kHz-6.5 MHz), high-power (>10 W) laser system at the X-ray Science Division 7-ID-D beamline at the Advanced...

8

Ultrafast Core-Hole Induced Dynamics in Water  

NLE Websites -- All DOE Office Websites (Extended Search)

Ultrafast Core-Hole Induced 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 turn affect subsequent chemical-reaction pathways. However, it is a fundamental challenge for the radiation chemistry community to unravel the early time dynamics of electronically excited states in water because their short (femtosecond) time scales are difficult to access directly 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 that the ultrafast (0- to 10-fs) dissociation dynamics of liquid water can be successfully probed with x-ray emission spectroscopy.

9

Ultrafast Magnetism Dynamics Measure Using Tabletop Ultrafast EUV Sources  

SciTech Connect

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.

Silva, Thomas J. [NIST] [NIST; Murnane, Margaret [University of Colorado] [University of Colorado

2013-08-21T23:59:59.000Z

10

Ultrafast dynamic ellipsometry and spectroscopy of laser shocked materials  

SciTech Connect

Ultrafast dynamic ellipsometry is used to measure the material motion and changes in the optical refractive index of laser shock compressed materials. This diagnostic has shown us that the ultrafast laser driven shocks are the same as shocks on longer timescales and larger length scales. We have added spectroscopic diagnostics of infrared absorption, ultra-violet - visible transient absorption, and femtosecond stimulated Raman scattering to begin probing the initiation chemistry that occurs in shock reactive materials. We have also used the femtosecond stimulated Raman scattering to measure the vibrational temperature of materials using the Stokes gain to anti-Stokes loss ratio.

Bolme, Cynthia A [Los Alamos National Laboratory; Mc Grane, Shawn D [Los Alamos National Laboratory; Dang, Nhan C [Los Alamos National Laboratory; Whitley, Von H [Los Alamos National Laboratory; Moore, David S. [Los Alamos National Laboratory

2011-01-20T23:59:59.000Z

11

Picosecond spectroscopy and solvation clusters. The dynamics of localizing electrons in polar fluids  

SciTech Connect

New spectroscopic evidence concerning the dynamics of electron-induced solvation clusters in polar liquids is presented and integrated with previous picosecond data, in order to outline the roles molecular dynamics and structure can play both in initiating electron localization at subpicosecond times and in governing the solvation dynamics to form e/sup -//sub s/ in the picosecond domain. Particulr emphasis is placed on the picosecond time-resolved absorption spectroscopy of electrons in a wide range of alcohols and alcohol-alkane systems at 300/sup 0/K as a framework for the cluster model of electron solvation. While the configurationally relaxed final quantum state of e/sup -//sub s/ appears identical for e/sup -//sub s/ generated by different techniques, it is possible that the time evolution of the solvation cluster and the dynamics of electron populations between localized and continuum states could be influenced by the initial state of the system. Selected examples are discussed for alcohols, amines, and water, and comparisons are made for picosecond observations from different visible and IR spectroscopic techniques, NMR, and complementary nanosecond electron mobility data to demonstrate the overall consistency of a model in which only the dynamical, microscopic properties of the liquid determine these solvation events.

Kenney-Wallace, G.A. (Univ. of Toronto, Ontario); Jonah, C.D.

1982-07-08T23:59:59.000Z

12

Ultrafast Core-Hole Induced Dynamics in Water  

NLE Websites -- All DOE Office Websites (Extended Search)

Ultrafast Core-Hole Induced Dynamics in Water Print 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 challenge for the radiation chemistry community to unravel the early time dynamics of electronically excited states in water because their short (femtosecond) time scales are difficult to access directly 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 that the ultrafast (0- to 10-fs) dissociation dynamics of liquid water can be successfully probed with x-ray emission spectroscopy.

13

Ultrafast Core-Hole Induced Dynamics in Water  

NLE Websites -- All DOE Office Websites (Extended Search)

Ultrafast Core-Hole Induced Dynamics in Water Print 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 challenge for the radiation chemistry community to unravel the early time dynamics of electronically excited states in water because their short (femtosecond) time scales are difficult to access directly 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 that the ultrafast (0- to 10-fs) dissociation dynamics of liquid water can be successfully probed with x-ray emission spectroscopy.

14

Ultrafast Core-Hole Induced Dynamics in Water  

NLE Websites -- All DOE Office Websites (Extended Search)

Ultrafast Core-Hole Induced Dynamics in Water Print 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 challenge for the radiation chemistry community to unravel the early time dynamics of electronically excited states in water because their short (femtosecond) time scales are difficult to access directly 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 that the ultrafast (0- to 10-fs) dissociation dynamics of liquid water can be successfully probed with x-ray emission spectroscopy.

15

Dynamical Fluctuating Charge Force Fields: The Aqueous Solvation of Amides  

E-Print Network (OSTI)

on the environment, is a convenient model for treating all of these effects: conformational changes, functional group/mol.3 The free energy difference between the two conformers in water,4,5 given by nuclear magnetic to the environment, is applied to the aqueous solvation of acetamide and trans- and cis- N-methylacetamide (NMA). Two

Berne, Bruce J.

16

Ultrafast dynamics of excitons in tetracene single crystals  

SciTech Connect

Ultrafast exciton dynamics in free standing 200 nm thin tetracene single crystals were studied at room temperature by femtosecond transient absorption spectroscopy in the visible spectral range. The complex spectrally overlapping transient absorption traces of single crystals were systematically deconvoluted. From this, the ultrafast dynamics of the ground, excited, and transition states were identified including singlet exciton fission into two triplet excitons. Fission is generated through both, direct fission of higher singlet states S{sub n} on a sub-picosecond timescale, and thermally activated fission of the singlet exciton S{sub 1} on a 40 ps timescale. The high energy Davydov component of the S{sub 1} exciton is proposed to undergo fission on a sub-picoseconds timescale. At high density of triplet excitons their mutual annihilation (triplet-triplet annihilation) occurs on a <10 ps timescale.

Birech, Zephania; Schwoerer, Heinrich, E-mail: heso@sun.ac.za [Laser Research Institute, Stellenbosch University, Stellenbosch 7600 (South Africa)] [Laser Research Institute, Stellenbosch University, Stellenbosch 7600 (South Africa); Schwoerer, Markus [Department of Physics, University of Bayreuth, Bayreuth (Germany)] [Department of Physics, University of Bayreuth, Bayreuth (Germany); Schmeiler, Teresa; Pflaum, Jens [Experimental Physics VI, University of Würzburg and Bavarian Center for Applied Energy Research, Würzburg (Germany)] [Experimental Physics VI, University of Würzburg and Bavarian Center for Applied Energy Research, Würzburg (Germany)

2014-03-21T23:59:59.000Z

17

Optical Probing of the Ultrafast Charge Carrier Motion Dynamics in Organic Solar Cells  

Science Journals Connector (OSTI)

We demonstrate application of the electric field-induced second harmonic generation as a probe of ultrafast electric field dynamics in thin molecular film, used for investigation of...

Gulbinas, Vidmantas

18

Ultrafast dynamics of the laser-induced solid-to-liquid phase transition in aluminum  

E-Print Network (OSTI)

Ultrafast dynamics of the laser-induced solid-to-liquid phase transition in aluminum A thesis dynamics of the laser-induced solid-to-liquid phase transition in aluminum Eric Mazur Maria Kandyla Abstract This dissertation reports the ultrafast dynamics of aluminum during the solid-to- liquid phase

Mazur, Eric

19

Ultrafast population dynamics in electrically modulated terahertz quantum cascade lasers  

Science Journals Connector (OSTI)

The ultrafast population dynamics in electrically modulated three-well terahertz quantum cascade lasers (QCLs) is studied by using the self-consistent Bloch–Poisson equations. In the modulation process, the non-equilibrium oscillations of the population inversion are found before the population equilibrium recovers. The equilibrium formation time increases nonlinearly with the period number. This phenomenon stems from the non-uniform distribution of the electric potential. In different periods, different responses to the electrical modulation are also explored. An in-depth understanding of electron transport in the cascade structure is obtained. Finally, we demonstrate the feasibility of a modulation frequency up to gigahertz in terahertz QCLs.

F Wang; X G Guo; C Wang; J C Cao

2013-01-01T23:59:59.000Z

20

Hydrogen Bond Dynamics Probed with Ultrafast Infrared Heterodyne-Detected Multidimensional Vibrational Stimulated Echoes  

E-Print Network (OSTI)

Hydrogen Bond Dynamics Probed with Ultrafast Infrared Heterodyne-Detected Multidimensional, USA (Received 24 February 2003; published 3 December 2003) Hydrogen bond dynamics are explicated hydrogen bonded network are measured with ultrashort (

Fayer, Michael D.

Note: This page contains sample records for the topic "ultrafast solvation dynamics" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


21

Ultrafast carrier dynamics in semiconductor quantum dots  

Science Journals Connector (OSTI)

The dynamics of band-edge photoluminescence (PL) in CdS nanocrystals (NC’s) dispersed in a glass matrix are studied with the femtosecond up-conversion technique. The time-resolved PL spectra exhibit several discrete features (three of them are in the NC energy band gap) which are not pronounced in a cw PL spectrum. The initial stage of a PL decay is governed by a depopulation of the lowest extended states due to carrier trapping (localization) on the time scale of 1 ps. The low-energy bands originating from the extended-to-localized state transitions exhibit extremely fast buildup dynamics (rise time is 400–700 fs) which is explained by the preexisting occupation of the localized states. © 1996 The American Physical Society.

V. Klimov; P. Haring Bolivar; H. Kurz

1996-01-15T23:59:59.000Z

22

Ultrafast dynamic ellipsometry and spectroscopy of laser shocked materials  

SciTech Connect

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.

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

2010-01-01T23:59:59.000Z

23

Variable-temperature emission studies of solvation dynamics: Evidence for coupling of solvation to chromophore structural dynamics in the evolution of charge-transfer excited states  

SciTech Connect

Variable-temperature emission data over the range 90--298 K have been collected for a series of bipyridyl complexes of Ru{sup II}. Spectra obtained for [Ru(dmb){sub 3}]{sup 2+} (dmb = 4,4{prime}-dimethyl-2,2{prime}-bipyridine), [Ru(dpb){sub 3}]{sup 2+} (dpb = 4,4{prime}-diphenyl-2,2{prime}-bipyridine), [Ru(dotb){sub 3}]{sup 2+} (dotb = 4,4{prime}-di-o-tolyl-2,2{prime}-bipyridine), and [Ru(dmesb){sub 3}]{sup 2+} (dmesb = 4,4{prime}-dimesityl-2,2{prime}-bipyridine) in 4:1 EtOH/MeOH show similar trends in terms of both the red shift of the emission spectrum and the thermal breadth of the solvent response as the temperature is increased through the glass-to-fluid transition. In contrast, data collected in 2-MeTHF show a strong dependence on the identity of the chromophore, the details of the spectral evolution qualitatively correlating with changes in the steric demands of the system. The most dramatic effect is observed for [Ru(dmesb){sub 3}]{sup 2+}, in which there is an apparent change in the nature of the emitting species with increasing temperature. These observations suggest a strong coupling of solvation dynamics and solute structure in the low-temperature regime as well as at intermediate temperatures where the structure of the chromophore is evolving in the course of excited-state relaxation. The results underscore the potential importance of specific solvent-solute interactions in the dynamics of solvation for cases in which large-amplitude molecular motion of the chromophore accompanies thermalization of the excited state.

Damrauer, N.H.; McCusker, J.K.

1999-09-20T23:59:59.000Z

24

Simulation of ultrafast heating induced structural dynamics using a one-dimensional spring model  

Science Journals Connector (OSTI)

We developed a one-dimensional spring model to study the dynamics of lattice motion upon ultrafast laser heating. Using this model, we simulated atomic positions as a function of time in a free-standing thin monoatomic metal film as well as in a thin film on a substrate. In particular, we studied how the electronic thermal stress influences lattice expansion after the ultrafast laser heating. The simulation results agree very well with experimental data obtained with femtosecond electron diffraction.

Junjie Li; Rick Clinite; Xuan Wang; Jianming Cao

2009-07-22T23:59:59.000Z

25

Ultrafast Structural Dynamics in Combustion Relevant Model Systems  

SciTech Connect

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 molecule’s 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 molecule’s 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 electron’s 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 molecule’s 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

Weber, Peter M. [Brown University

2014-03-31T23:59:59.000Z

26

Solvation Structure and Mobility Mechanism of OH-:? A Car?Parrinello Molecular Dynamics Investigation of Alkaline Solutions  

Science Journals Connector (OSTI)

Solvation Structure and Mobility Mechanism of OH-:? A Car?Parrinello Molecular Dynamics Investigation of Alkaline Solutions ... Figure 17 Comparison of power spectra derived from deuterium velocity autocorrelation functions for pure water (dashed lines in both panels a and b), KOD (panel a) at 1.3 M (solid line) and 14 M (dotted line), and NaOD (panel b) at 1.5 M (solid line), 4.5 M (diamonds), and 15 M (dotted line). ... energy structure on the potential energy surface, because the water drifts to become attached to one of the first solvation shell waters. ...

Bin Chen; Ivaylo Ivanov; Jung Mee Park; Michele Parrinello; Michael L. Klein

2002-10-24T23:59:59.000Z

27

Solvation of Magnesium Dication: Molecular Dynamics Simulation and Vibrational Spectroscopic Study of Magnesium Chloride in Aqueous Solutions  

E-Print Network (OSTI)

Solvation of Magnesium Dication: Molecular Dynamics Simulation and Vibrational Spectroscopic Study of Magnesium Chloride in Aqueous Solutions Karen M. Callahan, Nadia N. Casillas-Ituarte, Martina Roeselova 26, 2010 Magnesium dication plays many significant roles in biochemistry. While it is available

28

Water Dynamics in Salt Solutions Studied with Ultrafast Two-Dimensional Infrared (2D IR)  

E-Print Network (OSTI)

Water Dynamics in Salt Solutions Studied with Ultrafast Two-Dimensional Infrared (2D IR RECEIVED ON FEBRUARY 3, 2009 C O N S P E C T U S Water is ubiquitous in nature, but it exists as pure water infrequently. From the ocean to biology, water molecules interact with a wide variety of dissolved species

Fayer, Michael D.

29

Ultrafast x-ray diffraction for measurements of structural dynamics in shocked metals  

SciTech Connect

An experiment on structural dynamics at the ultrafast time scale in shocked metal samples is presented. The technique development of an ultrafast x-ray diffractometer to generate 'molecular movies' is described. Preliminary results of static x-ray measurements of thin unshocked Ga samples are presented. Initial experiments use 200-300 mJ of a 100fs Ti:Sapphire laser to excite K-alpha x-ray emission in an aluminum wire. The x-ray emission is relayed using a spherical crystal to the sample target. Plans for experiments using Cu K-alpha emission will also be described.

Workman, J. B. (Jonathan B.); Keiter, P. A. (Paul A.); Kyrala, George A.; Roberts, J. P. (Jeffrey); Taylor, Antoinette J.,; Funk, D. J. (David J.)

2002-01-01T23:59:59.000Z

30

Probing Ion Channel Conformational Dynamics Using Simultaneous Single-Molecule Ultrafast Spectroscopy and Patch-Champ Electric Recording  

SciTech Connect

A new approach to probing single-molecule ion channel kinetics and conformational dynamics, patch-clamp confocal fluorescence microscopy (PCCFM), uses simultaneous ultrafast fluorescence spectroscopy and single-channel electric current recording.

Harms, Gregory S.; Orr, Galya; Lu, H Peter

2004-03-08T23:59:59.000Z

31

Ultrafast Core-Hole Induced Dynamics in Water  

NLE Websites -- All DOE Office Websites (Extended Search)

chemistry community to unravel the early time dynamics of electronically excited states in water because their short (femtosecond) time scales are difficult to access...

32

Solvation Properties of Microhydrated Sulfate Anion Clusters...  

NLE Websites -- All DOE Office Websites (Extended Search)

solvation shell, with 12 or 13 water molecules. We used ab initio molecular dynamics and electronic structure calculations based on density functional theory, with semilocal and...

33

Ultrafast intramolecular relaxation dynamics of Mg- and Zn-bacteriochlorophyll a  

SciTech Connect

Ultrafast excited-state dynamics of the photosynthetic pigment (Mg-)bacteriochlorophyll a and its Zn-substituted form were investigated by steady-state absorption/fluorescence and femtosecond pump-probe spectroscopic measurements. The obtained steady-state absorption and fluorescence spectra of bacteriochlorophyll a in solution showed that the central metal compound significantly affects the energy of the Q{sub x} state, but has almost no effect on the Q{sub y} state. Photo-induced absorption spectra were recorded upon excitation of Mg- and Zn-bacteriochlorophyll a into either their Q{sub x} or Q{sub y} state. By comparing the kinetic traces of transient absorption, ground-state beaching, and stimulated emission after excitation to the Q{sub x} or Q{sub y} state, we showed that the Q{sub x} state was substantially incorporated in the ultrafast excited-state dynamics of bacteriochlorophyll a. Based on these observations, the lifetime of the Q{sub x} state was determined to be 50 and 70 fs for Mg- and Zn-bacteriochlorophyll a, respectively, indicating that the lifetime was influenced by the central metal atom due to the change of the energy gap between the Q{sub x} and Q{sub y} states.

Kosumi, Daisuke [Osaka City University Advanced Research Institute for Natural Science and Technology, 3-3-138 Sugimoto, Sumiyoshi-ku, Osaka 558-8585 (Japan); CREST/JST, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012 (Japan); Nakagawa, Katsunori; Sakai, Shunsuke [Graduate School of Engineering, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya 466-8555 (Japan); Nagaoka, Yuya; Maruta, Satoshi; Sugisaki, Mitsuru [CREST/JST, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012 (Japan); Department of Physics, Graduate School of Science, Osaka City University, 3-3-138 Sugimoto, Sumiyoshi-ku, Osaka 558-8585 (Japan); Dewa, Takehisa [Graduate School of Engineering, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya 466-8555 (Japan); PRESTO/JST, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012 (Japan); Nango, Mamoru [The Osaka City University Advanced Research Institute for Natural Science and Technology, 3-3-138 Sugimoto, Sumiyoshi-ku, Osaka 558-8585 (Japan); CREST/JST, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012 (Japan); Graduate School of Engineering, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya 466-8555 (Japan); Hashimoto, Hideki [The Osaka City University Advanced Research Institute for Natural Science and Technology, 3-3-138 Sugimoto, Sumiyoshi-ku, Osaka 558-8585 (Japan); CREST/JST, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012 (Japan); Department of Physics, Graduate School of Science, Osaka City University, 3-3-138 Sugimoto, Sumiyoshi-ku, Osaka 558-8585 (Japan)

2013-07-21T23:59:59.000Z

34

Ultrafast X-Ray Spectroscopy as a Probe of Nonequilibrium Dynamics in  

NLE Websites -- All DOE Office Websites (Extended Search)

The Electronic Origin of Photoinduced Strain The Electronic Origin of Photoinduced Strain Modifying Proteins to Combat Disease Higher Temperature at the Earth's Core Clues about Rheumatoid Arthritis Damage Science Highlights Archives: 2013 | 2012 | 2011 | 2010 2009 | 2008 | 2007 | 2006 2005 | 2004 | 2003 | 2002 2001 | 2000 | 1998 | Subscribe to APS Science Highlights rss feed Ultrafast X-Ray Spectroscopy as a Probe of Nonequilibrium Dynamics in Ruthenium Complexes FEBRUARY 8, 2013 Bookmark and Share Copyright © 2012 Elsevier B.V. All rights reserved. Exciting the atoms or molecules of a substance via the use of visible light, or photoexcitation, can play a significant role in a range of energy-conversion processes, such as natural photosynthesis (oxygen from water) and manmade solar cells (electricity from sunlight). But a better

35

A Novel Approach to Solvation Time Scale in Nonpolar Solvents via Instability of Solvent Density Modes  

E-Print Network (OSTI)

. The molecular processes underlying the rate-determining factors can be probed by the solvation time1, theoretical, and simulation techniques have been extensively used to understand the solvation time in solvents to study the nonpolar solvation dynamics. Nonpolar solvation dynamics involves changes in the shape and

Biswas, Ranjit

36

Structure and Ultrafast Dynamics of White-Light-Emitting CdSe Nanocrystals  

SciTech Connect

White-light emission from ultrasmall CdSe nanocrystals offers an alternative approach to the realization of solid-state lighting as an appealing technology for consumers. Unfortunately, their extremely small size limits the feasibility of traditional methods for nanocrystal characterization. This paper reports the first images of their structure, which were obtained using aberration-corrected atomic number contrast scanning transmission electron microscopy (Z-STEM). With subangstrom resolution, Z-STEM is one of the few available methods that can be used to directly image the nanocrystal's structure. The initial images suggest that they are crystalline and approximately four lattice planes in diameter. In addition to the structure, for the first time, the exciton dynamics were measured at different wavelengths of the white-light spectrum using ultrafast fluorescence upconversion spectroscopy. The data suggest that a myriad of trap states are responsible for the broad-spectrum emission. It is hoped that the information presented here will provide a foundation for the future development and improvement of white-light-emitting nanocrystals.

Bowers, Michael J [Vanderbilt University; McBride, James [Vanderbilt University; Garrett, Maria Danielle [Vanderbilt University; Sammons, Jessica A. [Vanderbilt University; Dukes, Albert [Vanderbilt University; Schreuder, Michael A. [Vanderbilt University; Watt, Tony L. [Vanderbilt University; Lupini, Andrew R [ORNL; Pennycook, Stephen J [ORNL; Rosenthal, Sandra [Vanderbilt University

2009-01-01T23:59:59.000Z

37

Solvation Structure of Hydroxyl Radical by Car?Parrinello Molecular Dynamics  

Science Journals Connector (OSTI)

Car?Parrinello molecular dynamics simulations of a hydroxyl radical in liquid water have been performed. ... A hydrogen bond between the two waters is formed and the first water molecule is pushed toward the hydroxyl. ... The resulting velocity autocorrelation power spectra calculated separately for the atomic species from the hydroxyl and from the water molecules are shown in Figure 12. ...

Julia M. Khalack; Alexander P. Lyubartsev

2004-12-07T23:59:59.000Z

38

Backbone Additivity in the Transfer Model of Protein Solvation...  

NLE Websites -- All DOE Office Websites (Extended Search)

Solvation. Abstract: The transfer model implying additivity of the peptide backbone free energy of transfer is computationally tested. Molecular dynamics simulations are used...

39

Solvation effects on chemical reaction dynamics in clusters: Photodissociation of HI in XeNHI  

Science Journals Connector (OSTI)

The photodissociation of HI in clusters of the type XeNHI is studied theoretically to explore the possible occurrence and dynamics of the cage effect in small clusters (from N=1 to 12). The method used describes the H atom quantum mechanically, the heavy atoms classically. It is found that a cage effect, corresponding to transient vibrations of the H between heavy atoms, exists for all clusters, including XeHI. For N5 the resonances are long lived and dominate the process. Steric and structural factors cause this behavior.

R. Alimi and R. B. Gerber

1990-03-19T23:59:59.000Z

40

Molecular Dynamics - Solvated Interaction Energy Studies of Protein-Protein Interactions; The MP1-p14 Scaffolding Complex  

SciTech Connect

Using the MP1-p14 scaffolding complex from the mitogen-activated protein kinase signaling pathway as model system, we explored a structure-based computational protocol to probe and characterize binding affinity hot spots at protein-protein interfaces. Hot spots are located by virtual alanine-scanning consensus predictions over three different energy functions and two different single-structure representations of the complex. Refined binding affinity predictions for select hot-spot mutations are carried out by applying first-principle methods such as the molecular mechanics generalized Born surface area (MM-GBSA) and solvated interaction energy (SIE) to the molecular dynamics (MD) trajectories for mutated and wild-type complexes. Here, predicted hot-spot residues were actually mutated to alanine, and crystal structures of the mutated complexes were determined. Two mutated MP1-p14 complexes were investigated, the p14(Y56A)-mutated complex and the MP1(L63A, L65A)-mutated complex. Alternative ways to generate MD ensembles for mutant complexes, not relying on crystal structures for mutated complexes, were also investigated. The SIE function, fitted on protein-ligand binding affinities, gave absolute binding affinity predictions in excellent agreement with experiment and outperformed standard MM-GBSA predictions when tested on the MD ensembles of Ras-Raf and Ras-RalGDS protein-protein complexes. For wild-type and mutant MP1-p14 complexes, SIE predictions of relative binding affinities were supported by a yeast two-hybrid assay that provided semiquantitative relative interaction strengths. Results on the MP1-mutated complex suggested that SIE predictions deteriorate if mutant MD ensembles are approximated by just mutating the wild-type MD trajectory. The SIE data on the p14-mutated complex indicated feasibility for generating mutant MD ensembles from mutated wild-type crystal structure, despite local structural differences observed upon mutation. For energetic considerations, this would circumvent costly needs to produce and crystallize mutated complexes. The sensitized protein-protein interface afforded by the p14(Y56A) mutation identified here has practical applications in screening-based discovery of first-generation small-molecule hits for further development into specific modulators of the mitogen-activated protein kinase signaling pathway.

Cui,Q.; Sulea, T.; Schrag, J.; Munger, C.; Hung, M.; Naim, M.; Cygler, M.; Purisima, E.

2008-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "ultrafast solvation dynamics" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


41

Investigation of ultrafast photothermal surface expansion and diffusivity in GaAs via laser-induced dynamic gratings  

SciTech Connect

This thesis details the first direct ultrafast measurements of the dynamic thermal expansion of a surface and the temperature dependent surface thermal diffusivity using a two-color reflection transient grating technique. Studies were performed on p-type, n-type, and undoped GaAs(100) samples over a wide range of temperatures. By utilizing a 90 fs ultraviolet probe with visible excitation beams, the effects of interband saturation and carrier dynamics become negligible; thus lattice expansion due to heating and subsequent contraction caused by cooling provided the dominant influence on the probe. At room temperature a rise due to thermal expansion was observed, corresponding to a maximum net displacement of {approximately} 1 {Angstrom} at 32 ps. The diffracted signal was composed of two components, thermal expansion of the surface and heat flow away from the surface, thus allowing a determination of the rate of expansion as well as the surface thermal diffusivity, D{sub S}. By varying the fringe spacing of the grating, this technique has the potential to separate the signal contributions to the expansion of the lattice in the perpendicular and parallel directions. In the data presented here a large fringe spacing was used, thus the dominant contribution to the rising edge of the signal was expansion perpendicular to the surface. Comparison of he results with a straightforward thermal model yields good agreement over a range of temperatures (20--300{degrees}K). Values for D{sub S} in GaAs were measured and found to be in reasonable agreement with bulk values above 50{degrees}K. Below 50{degrees}K, D{sub S} were determined to be up to an order of magnitude slower than the bulk diffusivity due to increased phonon boundary scattering. The applicability and advantages of the TG technique for studying photothermal and photoacoustic phenomena are discussed.

Pennington, D.M.

1992-04-01T23:59:59.000Z

42

Ultrafast THz Studies of Few-Layer Epitaxial Graphene  

Science Journals Connector (OSTI)

We report the broadband optical conductivity and ultrafast THz dynamics of few-layer epitaxial graphene, revealing electrodynamics consistent with a dense Dirac electron plasma and a...

Choi, Hyunyong; Borondics, Ferenc; Siegel, David A; Zhou, Shuyun; Martin, Michael C; Lanzara, Alessandra; Kaindl, Robert A

43

Ultrafast nuclear spin polarization for isotopes with large nuclear spin  

Science Journals Connector (OSTI)

We theoretically investigate the temporal dynamics of nuclear spin induced by short laser pulses. To realize ultrafast nuclear spin polarization, we coherently excite the hyperfine...

Nakajima, Takashi

2009-01-01T23:59:59.000Z

44

Dynamics of water and aqueous protons studied using ultrafast multi-dimensional infrared spectroscopy  

E-Print Network (OSTI)

Liquid water consists of a highly dynamic network of hydrogen bonds, which evolves on timescales ranging from tens of femtoseconds to a few picoseconds. The fast structural evolution of water's hydrogen bond network is at ...

Ramasesha, Krupa

2013-01-01T23:59:59.000Z

45

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

SciTech Connect

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.

Whitley, Von H [Los Alamos National Laboratory; Mcgrane, Shawn D [Los Alamos National Laboratory; Moore, David S [Los Alamos National Laboratory; Eakins, Dan E [Los Alamos National Laboratory; Bolme, Cindy A [Los Alamos National Laboratory

2009-01-01T23:59:59.000Z

46

Ultrafast Laser Facility | Photosynthetic Antenna Research Center  

NLE Websites -- All DOE Office Websites (Extended Search)

Ultrafast Laser Facility Ultrafast Laser Facility Click for an Overview of the Ultrafast Laser Facility The PARC Ultrafast Laser Facility, under the direction of Associate Director...

47

Ultrafast Electron Dynamics in Gold in the Presence of Laser Excited Surface Plasma Waves  

SciTech Connect

Surface plasmon excitation with ultrashort intense laser pulses enhances efficiently laser absorption in metals and creates local high fields and non-equilibrium hot electrons population that have attractivity for numerous applications such as the development of intense sources of high-energy particles or photons and in the fast ignitor scheme in the framework of inertial fusion. In this context, the knowledge of the dynamics of relaxation of the collective electrons behavior is of importance. Using gold grating, we have investigated electrons relaxation in the presence of laser excited surface plasmon waves using a multiple-wavelengh femtosecond pump-probe technique. The results yield evidence of longer relaxation time in the presence of the collective excitation than that of individual electronic states.

Raynaud, M. [CEA/DSM/IRAMIS/LSI, Ecole Polytechnique, 91128 Palaiseau (France); Geoffroy, G.; Perdrix, M. [CEA/DSM/IRAMIS/SPAM, 91191 Gif-sur-Yvette (France); Martin, P. [CELIA, Universite Bordeaux 1-CEA-CNRS, 33405 Talence (France)

2010-02-02T23:59:59.000Z

48

Ultrafast X-ray Absorption Spectroscopy using Laser-Driven Electron X-ray Sources (LEXS)  

E-Print Network (OSTI)

: ultrafast x-rays, x-ray absorption spectroscopy, terawatt lasers, ultrafast reaction dynamics, atomic motion atomic motion by scrutinizing the changes in x- ray absorption spectra during reactions. FirstUltrafast X-ray Absorption Spectroscopy using Laser-Driven Electron X-ray Sources (LEXS) Guangjun

Guo, Ting

49

Ultrafast nonlinear optical properties of passive and active semiconductor devices  

E-Print Network (OSTI)

Nonlinear optical properties and ultrafast carrier dynamics of slab-coupled optical waveguide amplifiers, silicon nanowaveguides, and III-V semiconductor saturable Bragg reflectors are studied. The limits imposed by two ...

Motamedi, Ali Reza

2011-01-01T23:59:59.000Z

50

Preparation of cerium halide solvate complexes  

DOE Patents (OSTI)

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.

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

2013-08-06T23:59:59.000Z

51

Optical Detection in Ultrafast Short Wavelength Science  

SciTech Connect

A new approach to coherent detection of ionising radiation is briefly motivated and recounted. The approach involves optical scattering of coherent light fields by colour centres in transparent solids. It has significant potential for diffractive imaging applications that require high detection dynamic range from pulsed high brilliance short wavelength sources. It also motivates new incarnations of Bragg's X-ray microscope for pump-probe studies of ultrafast molecular structure-dynamics.

Fullagar, Wilfred K.; Hall, Chris J. [School of Physics, Monash University, Victoria 3800 (Australia); Monash Centre for Synchrotron Science, Monash University, Victoria 3800 (Australia); Centre of Excellence for Coherent X-ray Science, School of Physics, University of Melbourne, Victoria, 3010 (Australia)

2010-06-23T23:59:59.000Z

52

Vibrational coherence in the excited state dynamics of Cr(acac)3: probing the reaction coordinate for ultrafast intersystem crossing  

E-Print Network (OSTI)

Vibrational coherence in the excited state dynamics of Cr(acac)3: probing the reaction coordinateCusker* Received 12th April 2010, Accepted 29th May 2010 DOI: 10.1039/c0sc00262c Vibrational coherence was observed coherence; the timescale of the event suggests that this vibrational coherence is retained during the 4 T2

McCusker, James K.

53

Solvation thermodynamics and heat capacity of polar and charged solutes in water  

SciTech Connect

The solvation thermodynamics and in particular the solvation heat capacity of polar and charged solutes in water is studied using atomistic molecular dynamics simulations. As ionic solutes we consider a F{sup -} and a Na{sup +} ion, as an example for a polar molecule with vanishing net charge we take a SPC/E water molecule. The partial charges of all three solutes are varied in a wide range by a scaling factor. Using a recently introduced method for the accurate determination of the solvation free energy of polar solutes, we determine the free energy, entropy, enthalpy, and heat capacity of the three different solutes as a function of temperature and partial solute charge. We find that the sum of the solvation heat capacities of the Na{sup +} and F{sup -} ions is negative, in agreement with experimental observations, but our results uncover a pronounced difference in the heat capacity between positively and negatively charged groups. While the solvation heat capacity {Delta}C{sub p} stays positive and even increases slightly upon charging the Na{sup +} ion, it decreases upon charging the F{sup -} ion and becomes negative beyond an ion charge of q=-0.3e. On the other hand, the heat capacity of the overall charge-neutral polar solute derived from a SPC/E water molecule is positive for all charge scaling factors considered by us. This means that the heat capacity of a wide class of polar solutes with vanishing net charge is positive. The common ascription of negative heat capacities to polar chemical groups might arise from the neglect of non-additive interaction effects between polar and apolar groups. The reason behind this non-additivity is suggested to be related to the second solvation shell that significantly affects the solvation thermodynamics and due to its large spatial extent induces quite long-ranged interactions between solvated molecular parts and groups.

Sedlmeier, Felix; Netz, Roland R. [Fachbereich Physik, Freie Universitaet Berlin, 14195 Berlin (Germany)

2013-03-21T23:59:59.000Z

54

In Situ Laser Crystallization of Amorphous Silicon for TFT Applications: Controlled Ultrafast Studies in the Dynamic TEM  

SciTech Connect

An in situ method for studying the role of laser energy on the microstructural evolution of polycrystalline Si is presented. By monitoring both laser energy and microstructural evolution simultaneously in the dynamic transmission electron microscope, information on grain size and defect concentration can be correlated directly with processing conditions. This proof of principle study provides fundamental scientific information on the crystallization process that has technological importance for the development of thin film transistors. In conclusion, we successfully developed a method for studying UV laser processing of Si films in situ on nanosecond time scales, with ultimate implications for TFT application improvements. In addition to grain size distribution as a function of laser energy density, we found that grain size scaled with laser energy in general. We showed that nanosecond time resolution allowed us to see the nucleation and growth front during processing, which will help further the understanding of microstructural evolution of poly-Si films for electronic applications. Future studies, coupled with high resolution TEM, will be performed to study grain boundary migration, intergranular defects, and grain size distribution with respect to laser energy and adsorption depth.

Taheri, M; Teslich, N; Lu, J P; Morgan, D; Browning, N

2008-02-08T23:59:59.000Z

55

Plasmonic enhanced ultrafast switch.  

SciTech Connect

Ultrafast electronic switches fabricated from defective material have been used for several decades in order to produce picosecond electrical transients and TeraHertz radiation. Due to the ultrashort recombination time in the photoconductor materials used, these switches are inefficient and are ultimately limited by the amount of optical power that can be applied to the switch before self-destruction. The goal of this work is to create ultrafast (sub-picosecond response) photoconductive switches on GaAs that are enhanced through plasmonic coupling structures. Here, the plasmonic coupler primarily plays the role of being a radiation condenser which will cause carriers to be generated adjacent to metallic electrodes where they can more efficiently be collected.

Subramania,Ganapathi Subramanian; Reno, John Louis; Passmore, Brandon Scott; Harris, Tom.; Shaner, Eric Arthur; Barrick, Todd A.

2009-09-01T23:59:59.000Z

56

Ultrafast supercontinuum fiber-laser based pump-probe scanning magneto-optical Kerr effect microscope for the investigation of electron spin dynamics in semiconductors at cryogenic temperatures with picosecond time and micrometer spatial resolution  

SciTech Connect

We describe a two-color pump-probe scanning magneto-optical Kerr effect microscope which we have developed to investigate electron spin phenomena in semiconductors at cryogenic temperatures with picosecond time and micrometer spatial resolution. The key innovation of our microscope is the usage of an ultrafast “white light” supercontinuum fiber-laser source which provides access to the whole visible and near-infrared spectral range. Our Kerr microscope allows for the independent selection of the excitation and detection energy while avoiding the necessity to synchronize the pulse trains of two separate picosecond laser systems. The ability to independently tune the pump and probe wavelength enables the investigation of the influence of excitation energy on the optically induced electron spin dynamics in semiconductors. We demonstrate picosecond real-space imaging of the diffusive expansion of optically excited electron spin packets in a (110) GaAs quantum well sample to illustrate the capabilities of the instrument.

Henn, T.; Kiessling, T., E-mail: tobias.kiessling@physik.uni-wuerzburg.de; Ossau, W.; Molenkamp, L. W. [Physikalisches Institut (EP3), Universität Würzburg, 97074 Würzburg (Germany)] [Physikalisches Institut (EP3), Universität Würzburg, 97074 Würzburg (Germany); Biermann, K.; Santos, P. V. [Paul-Drude-Institut für Festkörperelektronik, 10117 Berlin (Germany)] [Paul-Drude-Institut für Festkörperelektronik, 10117 Berlin (Germany)

2013-12-15T23:59:59.000Z

57

Photo-Induced Spin-State Conversion in Solvated Transition Metal Complexes Probed via Time-Resolved Soft X-ray Spectroscopy  

E-Print Network (OSTI)

Photo-Induced Spin-State Conversion in Solvated TransitionAbstract: Solution-phase photo-induced low-spin to high-spinquestions concerning photo-induced dynamics difficult to

Huse, Nils

2010-01-01T23:59:59.000Z

58

Ultrafast electron beam imaging of femtosecond laser-induced plasma  

NLE Websites -- All DOE Office Websites (Extended Search)

Ultrafast electron beam imaging of femtosecond laser-induced plasma Ultrafast electron beam imaging of femtosecond laser-induced plasma dynamics Title Ultrafast electron beam imaging of femtosecond laser-induced plasma dynamics Publication Type Journal Article Year of Publication 2010 Authors Li, Junjie, Xuan Wang, Zhaoyang Chen, Richard Clinite, Samuel S. Mao, Pengfei Zhu, Zhengming Sheng, Jie Zhang, and Jianming Cao Journal Journal of Applied Physics Volume 107 Issue 8 Date Published 03/2010 Keywords copper, electron beam applications, high-speed optical techniques, laser ablation, plasma diagnostics, plasma production by laser Abstract Plasma dynamics in the early stage of laser ablation of a copper target are investigated in real time by making ultrafast electron shadow images and electron deflectometry measurements. These complementary techniques provide both a global view and a local perspective of the associated transient electric field and charge expansion dynamics. The results reveal that the charge cloud above the target surface is composed predominantly of thermally ejected electrons and that it is self-expanding, with a fast front-layer speed exceeding 107 m/s. The average electric field strength of the charge cloud induced by a pump fluence of 2.2 J/cm2 is estimated to be ∼ 2.4×105 V/m.

59

Ultrafast thermalization of photoexcited carriers in polar semiconductors  

Science Journals Connector (OSTI)

We present a combined experimental and theoretical study of ultrafast thermalization of high-energy carriers photogenerated by femtosecond laser excitation in GaAs and InP. Luminescence up-conversion is used to monitor the spectral and temporal evolution of the carrier distribution with a time resolution of about 100 fs. A rapid redistribution of electrons and holes over a wide energy range is found within the first 100 fs after excitation. The experimental results are analyzed by Monte Carlo simulations including a molecular-dynamics scheme to describe the carrier kinetics. We show that the Coulomb interaction among carriers is responsible for the initial ultrafast thermalization.

Lucio Rota; Paolo Lugli; Thomas Elsaesser; Jagdeep Shah

1993-02-15T23:59:59.000Z

60

Femtosecond laser studies of ultrafast intramolecular processes  

SciTech Connect

The goal of this research is to better understand the detailed mechanisms of chemical reactions by observing, directly in time, the dynamics of fundamental chemical processes. In this work femtosecond laser pulses are used to initiate chemical processes and follow the progress of these processes in time. The authors are currently studying ultrafast internal conversion and subsequent intramolecular relaxation in unsaturated hydrocarbons. In addition, the authors are developing nonlinear optical techniques to prepare and monitor the time evolution of specific vibrational motions in ground electronic state molecules.

Hayden, C. [Sandia National Laboratories, Livermore, CA (United States)

1993-12-01T23:59:59.000Z

Note: This page contains sample records for the topic "ultrafast solvation dynamics" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


61

THz Carrier Dynamics in Epitaxial Graphene  

Science Journals Connector (OSTI)

Ultrafast optical pump/THz-probe spectroscopy is used to measure the conductivity recovery dynamics in epitaxial graphene. The observed dynamics are insensitive to probe frequency,...

Divin, Charles J; Sun, Dong; Berger, Claire; de Heer, Walt; First, P N; Norris, Theodore B

62

Reactions of Solvated Ions Final Report  

DOE R&D Accomplishments (OSTI)

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.)

Taube, H.

1962-09-24T23:59:59.000Z

63

Watching a Protein as it Functions | Advanced Photon Source  

NLE Websites -- All DOE Office Websites (Extended Search)

for Warm-White LEDs Probing Ultrafast Solvation Dynamics with High Repetition-Rate LaserX-ray Methodologies Science Highlights Archives: 2014 2013 | 2012 | 2011 | 2010 2009...

64

Single-Molecule Solvation-Shell Sensing  

Science Journals Connector (OSTI)

We present a new route to single-molecule sensing via solvation shells surrounding a current-carrying backbone molecule. As an example, we show that the presence of a water solvation shell “gates” the conductance of a family of oligothiophene-containing molecular wires, and that the longer the oligothiophene, the larger is the effect. For the longest example studied, the molecular conductance is over 2 orders of magnitude larger in the presence of a shell comprising just 10 water molecules. A first principles theoretical investigation of electron transport through the molecules, using the nonequilibrium Green’s function method, shows that water molecules interact directly with the thiophene rings, significantly shifting transport resonances and greatly increasing the conductance. This reversible effect is confirmed experimentally through conductance measurements performed in the presence of moist air and dry argon.

E. Leary; H. Höbenreich; S. J. Higgins; H. van Zalinge; W. Haiss; R. J. Nichols; C. M. Finch; I. Grace; C. J. Lambert; R. McGrath; J. Smerdon

2009-02-23T23:59:59.000Z

65

Ultrafast Graphene Oxide Humidity Sensors  

Science Journals Connector (OSTI)

Ultrafast Graphene Oxide Humidity Sensors ... Graphene oxide can be exploited in humidity and temperature sensors with a number of convenient features such as flexibility, transparency and suitability for large-scale manufacturing. ... Here we show that the two-dimensional nature of graphene oxide and its superpermeability to water combine to enable humidity sensors with unprecedented response speed (?30 ms response and recovery times). ...

Stefano Borini; Richard White; Di Wei; Michael Astley; Samiul Haque; Elisabetta Spigone; Nadine Harris; Jani Kivioja; Tapani Ryhänen

2013-11-09T23:59:59.000Z

66

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

NLE Websites -- All DOE Office Websites (Extended Search)

The ALS X-Ray Streak Camera: Bringing the Ultrafast and Ultrasmall into Focus Print 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 the ultrafast details of the dynamical processes. ALS researchers are taking the second path but adding a spatial resolution capability; that is, they are developing a high-speed x-ray streak camera with high spatial resolution to watch, in real time, the motion of the atoms in materials. So far, a temporal resolution of 233 fs and a spatial resolution of 10 mm have been demonstrated. This is the first time that such a high temporal resolution has been combined with high spatial resolution in a streak camera.

67

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

NLE Websites -- All DOE Office Websites (Extended Search)

The ALS X-Ray Streak Camera: Bringing the Ultrafast and Ultrasmall into Focus Print 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 the ultrafast details of the dynamical processes. ALS researchers are taking the second path but adding a spatial resolution capability; that is, they are developing a high-speed x-ray streak camera with high spatial resolution to watch, in real time, the motion of the atoms in materials. So far, a temporal resolution of 233 fs and a spatial resolution of 10 mm have been demonstrated. This is the first time that such a high temporal resolution has been combined with high spatial resolution in a streak camera.

68

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

NLE Websites -- All DOE Office Websites (Extended Search)

The ALS X-Ray Streak Camera: Bringing the Ultrafast and Ultrasmall into Focus Print 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 the ultrafast details of the dynamical processes. ALS researchers are taking the second path but adding a spatial resolution capability; that is, they are developing a high-speed x-ray streak camera with high spatial resolution to watch, in real time, the motion of the atoms in materials. So far, a temporal resolution of 233 fs and a spatial resolution of 10 mm have been demonstrated. This is the first time that such a high temporal resolution has been combined with high spatial resolution in a streak camera.

69

Ultrafast Pump-Probe Studies of Excited-State Charge-Transfer Dynamics in Blue Copper Lewis D. Book, David C. Arnett, Hanbo Hu, and Norbert F. Scherer*,  

E-Print Network (OSTI)

and the James Franck Institute, UniVersity of Chicago, Chicago, Illinois 60637, EnVironmental Molecular Sciences, the coupling between the redox states, and the reorganization energy of nuclear degrees of freedom.4 Although It is especially difficult to study the effect of specific protein modes on dynamics in thermally activated

Scherer, Norbert F.

70

Ultrafast gigantic photo-response in charge-ordered organic salt (EDO-TTF)2PF6 on 10-fs time scales  

E-Print Network (OSTI)

Ultrafast Gigantic Photo-Response in Charge- Ordered OrganicThe initial dynamics of photo-induced phase transition inobserved sub- 20-fs gigantic photo-responses (|?R/R|>100%)

Itatani, J.

2010-01-01T23:59:59.000Z

71

Internal friction in the ultrafast folding of the tryptophan cage q Linlin Qiu 1  

E-Print Network (OSTI)

Internal friction in the ultrafast folding of the tryptophan cage q Linlin Qiu 1 , Stephen J. Hagen is a diffusional process, and the speed of folding is controlled by the frictional forces that act important source of friction in folding reactions. By contrast, our studies of the folding dynamics

Hagen, Stephen J.

72

Water at the Surfaces of Aligned Phospholipid Multibilayer Model Membranes Probed with Ultrafast Vibrational  

E-Print Network (OSTI)

Water at the Surfaces of Aligned Phospholipid Multibilayer Model Membranes Probed with Ultrafast@stanford.edu Abstract: The dynamics of water at the surface of artificial membranes composed of aligned multibilayers pump-probe spectroscopy. The experiments are performed at various hydration levels, x ) 2 - 16 water

Fayer, Michael D.

73

NANO EXPRESS Open Access Ultrafast nano-oscillators based on interlayer-  

E-Print Network (OSTI)

NANO EXPRESS Open Access Ultrafast nano-oscillators based on interlayer- bridged carbon nanoscrolls nano-oscillators based on carbon nanoscrolls (CNSs) using molecular dynamics simulations. Initiated of gigahertz. We demonstrate an effective strategy to reduce the dissipation of the CNS-based nano

Li, Teng

74

Observation of off-Hugoniot shocked states with ultrafast time resolution  

SciTech Connect

We apply ultrafast single shot interferometry to determine the pressure and density of argon shocked from up to 7.8 GPa static initial pressure in a diamond anvil cell. This method enables the observation of thermodynamic states distinct from those observed in either single shock or isothermal compression experiments, and the observation of ultrafast dynamics in shocked materials. We also present a straightforward method for interpreting ultrafast shock wave data which determines the index of refraction at the shock front, and the particle and shock velocities for shock waves in transparent materials. Based on these methods, we observe shocked thermodynamic states between the room temperature isotherm of argon and the shock adiabat of cryogenic argon at final shock pressures up to 28 GPa.

Armstrong, M; Crowhurst, J; Bastea, S; Zaug, J

2010-02-23T23:59:59.000Z

75

4th-International Symposium on Ultrafast Surface Science - Final Report  

SciTech Connect

The 4-th International Symposium on Ultrafast Surface Dynamics (UDS4) was held at the Telluride Summer Research Center on June 22-27, 2003. The International Organizing Committee consisting of Hrvoje Petek (USA), Xiaoyang Zhu (USA), Pedro Echenique (Spain) and Maki Kawai (Japan) brought together a total of 51 participants 16 of whom were from Europe, 10 from Japan, and 25 from the USA. The focus of the conference was on ultrafast electron or light induced processes at well-defined surfaces. Ultrafast surface dynamics concerns the transfer of charge and energy at solid surfaces on the femtosecond time scale. These processes govern rates of fundamental steps in surface reactions, interfacial electron transfer in molecular electronics, and relaxation in spin transport. Recent developments in femtosecond laser technology make it possible to measure by a variety of nonlinear optical techniques directly in the time domain the microscopic rates underlying these interfacial processes. Parallel progress in scanning probe microscopy makes it possible at a single molecular level to perform the vibrational and electronic spectroscopy measurements, to induce reactions with tunneling electrons, and to observe their outcome. There is no doubt that successful development in the field of ultrafast surface dynamics will contribute to many important disciplines.

Hrvoje Petek

2005-01-26T23:59:59.000Z

76

Ultrafast X-Ray Sources and Science  

Science Journals Connector (OSTI)

X-ray science is entering the ultrafast and ultraintense era - spurred by developments in coherent, short-wavelength sources that range from tabletop to accelerator-based. These...

Young, Linda

77

Ultrafast superconductor digital electronics: RSFQ technology roadmap  

Science Journals Connector (OSTI)

This paper gives a brief review of the Rapid Single-Flux-Quantum (RSFQ) logic family which leads the race toward practical ultrafast superconductor digital electronics, with an attempt to sketch a “roadmap” for t...

Konstantin K. Likharev

1996-01-01T23:59:59.000Z

78

Ultrafast dynamics of electrons at interfaces  

SciTech Connect

Electronic states of a thin layer of material on a surface possess unique physical and chemical properties. Some of these properties arise from the reduced dimensionality of the thin layer with respect to the bulk or the properties of the electric field where two materials of differing dielectric constants meet at an interface. Other properties are related to the nature of the surface chemical bond. Here, the properties of excess electrons in thin layers of Xenon, Krypton, and alkali metals are investigated, and the bound state energies and effective masses of the excess electrons are determined using two-photon photoemission. For Xenon, the dependence of bound state energy, effective mass, and lifetime on layer thickness from one to nine layers is examined. Not all quantities were measured at each coverage. The two photon photoemission spectra of thin layers of Xenon on a Ag(111) substrate exhibit a number of sharp, well-defined peaks. The binding energy of the excess electronic states of Xenon layers exhibited a pronounced dependence on coverage. A discrete energy shift was observed for each additional atomic layer. At low coverage, a series of states resembling a Rydberg series is observed. This series is similar to the image state series observed on clean metal surfaces. Deviations from image state energies can be described in terms of the dielectric constant of the overlayer material and its effect on the image potential. For thicker layers of Xe (beyond the first few atomic layers), the coverage dependence of the features begins to resemble that of quantum well states. Quantum well states are related to bulk band states. However, the finite thickness of the layer restricts the perpendicular wavevector to a discrete set of values. Therefore, the spectrum of quantum well states contains a series of peaks which correspond to the various allowed values of the perpendicular wavevector. Analysis of the quantum well spectrum yields electronic band structure information. In this case, the quantum well states examined are derived from the Xenon conduction band. Measurements of the energies as a function of coverage yield the dispersion along the axis perpendicular to the surface while angle-resolved two-photon photoemission measurements yield information about dispersion along the surface parallel. The relative importance of the image potential and the overlayer band structure also depends on the quantum number and energy of the state. Some members of the image series may have an energy which is in an energy gap of the layer material, therefore such states may tend to remain physically outside the layer and retain much of their image character even at higher coverages. This is the case for the n = 1 image state of the Xe/Ag(111) system. The energies of image states which are excluded from the layer have a complex dependence on the thickness of the layer and its dielectric constant. The population decay kinetics of excited electronic states of the layer were also determined. Lifetimes are reported for the first three excited states for 1-6 atomic layers of Xe on Ag(111). As the image states evolve into quantum well states with increasing coverage, the lifetimes undergo an oscillation which marks a change in the spatial extent of the state. For example, the n = 2 quantum well state decreases substantially at 3-5 layers as the electron probability density in the layer increases. The lifetime data are modeled by extending the two-band nearly-free-electron approximation to account for the insulating Xe layer.

McNeill, Jason D.

1999-05-03T23:59:59.000Z

79

An ultrafast carbon nanotube terahertz polarisation modulator  

SciTech Connect

We demonstrate ultrafast modulation of terahertz radiation by unaligned optically pumped single-walled carbon nanotubes. Photoexcitation by an ultrafast optical pump pulse induces transient terahertz absorption in nanowires aligned parallel to the optical pump. By controlling the polarisation of the optical pump, we show that terahertz polarisation and modulation can be tuned, allowing sub-picosecond modulation of terahertz radiation. Such speeds suggest potential for semiconductor nanowire devices in terahertz communication technologies.

Docherty, Callum J.; Stranks, Samuel D.; Habisreutinger, Severin N.; Joyce, Hannah J.; Herz, Laura M.; Nicholas, Robin J.; Johnston, Michael B., E-mail: m.johnston@physics.ox.ac.uk [Department of Physics, University of Oxford, Clarendon Laboratory, Parks Road, Oxford OX1 3PU (United Kingdom)

2014-05-28T23:59:59.000Z

80

Standard electrode potential, Tafel equation, and the solvation thermodynamics  

Science Journals Connector (OSTI)

Equilibrium in the electronic subsystem across the solution-metal interface is considered to connect the standard electrode potential to the statistics of localized electronic states in solution. We argue that a correct derivation of the Nernst equation for the electrode potential requires a careful separation of the relevant time scales. An equation for the standard metal potential is derived linking it to the thermodynamics of solvation. The Anderson–Newns model for electronic delocalization between the solution and the electrode is combined with a bilinear model of solute-solvent coupling introducing nonlinear solvation into the theory of heterogeneous electron transfer. We therefore are capable of addressing the question of how nonlinear solvation affects electrochemical observables. The transfer coefficient of electrode kinetics is shown to be equal to the derivative of the free energy or generalized force required to shift the unoccupied electronic level in the bulk. The transfer coefficient thus directly quantifies the extent of nonlinear solvation of the redox couple. The current model allows the transfer coefficient to deviate from the value of 0.5 of the linear solvation models at zero electrode overpotential. The electrode current curves become asymmetric in respect to the change in the sign of the electrode overpotential.

Dmitry V. Matyushov

2009-01-01T23:59:59.000Z

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81

Standard electrode potential, Tafel equation, and the solvation thermodynamics  

SciTech Connect

Equilibrium in the electronic subsystem across the solution-metal interface is considered to connect the standard electrode potential to the statistics of localized electronic states in solution. We argue that a correct derivation of the Nernst equation for the electrode potential requires a careful separation of the relevant time scales. An equation for the standard metal potential is derived linking it to the thermodynamics of solvation. The Anderson-Newns model for electronic delocalization between the solution and the electrode is combined with a bilinear model of solute-solvent coupling introducing nonlinear solvation into the theory of heterogeneous electron transfer. We therefore are capable of addressing the question of how nonlinear solvation affects electrochemical observables. The transfer coefficient of electrode kinetics is shown to be equal to the derivative of the free energy, or generalized force, required to shift the unoccupied electronic level in the bulk. The transfer coefficient thus directly quantifies the extent of nonlinear solvation of the redox couple. The current model allows the transfer coefficient to deviate from the value of 0.5 of the linear solvation models at zero electrode overpotential. The electrode current curves become asymmetric in respect to the change in the sign of the electrode overpotential.

Matyushov, Dmitry V. [Center for Biological Physics, Arizona State University, P.O. Box 871504, Tempe, Arizona 85287-1504 (United States)

2009-06-21T23:59:59.000Z

82

SISGR: Linking Ion Solvation and Lithium Battery Electrolyte Properties  

SciTech Connect

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-Ã?Â?Ã?Â?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.

Trulove, Paul C; Foley, Matthew P

2013-03-14T23:59:59.000Z

83

Studies of cosolvent systems in supercritical ethane using solvated electrons.  

SciTech Connect

In this paper, pulse-radiolytic studies of the methanol-ethane cosolvent system are carried out. Our results show that at temperatures below approximately 110 C, there are high local concentrations of alcohols (clusters) that are capable of solvating an electron, suggesting a size of approximately 4-5 methanol molecules at approximately 0.15 mole fraction alcohol. Reactions have been carried out between these solvated electrons and silver ions that are (presumably) dissolved in other small clusters of alcohols. These results show that the reaction between species in two different clusters is approximately 2 orders of magnitude slower than diffusion-controlled reactions.

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

2000-11-14T23:59:59.000Z

84

Ultrafast Spectroscopy of Warm Dense Matter  

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Ultrafast Spectroscopy of Warm Dense Matter Print 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 temperatures and pressures, WDM tends to be drastically transient and thus difficult to study in the laboratory. Now, researchers have set up ultrafast x-ray absorption spectroscopy at the ALS to measure the electronic structure of WDMs, demonstrating that fast-changing electron temperatures of matter under extreme conditions can be determined with picosecond resolution.

85

Lab-based Ultrafast Molecular Structure  

SciTech Connect

The proliferation of various laser-driven approaches to sub-picosecond hard X-ray and short-wavelength radiation generation in the past few decades has opened many avenues for the laboratory-based development of traditionally facility-based short wavelength ultrafast molecular structure science. Together with the introduction of microcalorimeter detection schemes, this opens the floodgates to widespread, decentralized implementation of what were until recently specialist short wavelength techniques. A parallel situation exists for the contemporary adoption of sub-wavelength resolution optical microscopies. In what follows, a few ultrafast molecular structure developments and their rationale are briefly recounted.

Fullagar, Wilfred [Division of Chemical Physics, Lund University, P.O. Box 124, SE-22100 Lund (Sweden); Monash Centre for Synchrotron Science / Monash School of Physics / Centre of Excellence for Coherent X-ray Science, Monash University, Clayton, VIC 3800 (Australia); Uhlig, Jens; Gador, Niklas; Maasilta, Ilari; Sundstroem, Villy [Division of Chemical Physics, Lund University, P.O. Box 124, SE-22100 Lund (Sweden); Kinnuen, Kimmo [Division of Chemical Physics, Lund University, P.O. Box 124, SE-22100 Lund (Sweden); Nanoscience Center, P.O.Box 35, FI-40014 University of Jyvaeskylae (Finland); Wahlstroem, Claes-Goeran [Division of Atomic Physics, Lund Institute of Technology, P.O. Box 118, SE-22100 Lund (Sweden)

2010-06-23T23:59:59.000Z

86

Ultrafast Control of Magnetism in Ferromagnetic Semiconductors via Photoexcited Transient Carriers  

E-Print Network (OSTI)

Magneto-Optics in Nickel: Magnetism or Optics? ” Phys. Rev.Ultrafast Control of Magnetism in FerromagneticFall 2008 Ultrafast Control of Magnetism in Ferromagnetic

Cotoros, Ingrid A.

2009-01-01T23:59:59.000Z

87

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...

88

Modified ultrafast thermometer UFT-M and temperature measurements during Physics of Stratocumulus Top (POST)  

E-Print Network (OSTI)

al. : Modified ultrafast thermometer UFT-M and temperatureR. : A new ultrafast thermometer for airborne measurementsof some airborne thermometers in clouds, J. Atmos. Ocean.

Kumala, W.; Haman, K. E; Kopec, M. K; Khelif, D.; Malinowski, S. P

2013-01-01T23:59:59.000Z

89

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

SciTech Connect

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).

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

2014-09-30T23:59:59.000Z

90

Structural Interactions within Lithium Salt Solvates: Cyclic Carbonates and Esters  

SciTech Connect

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 packing—in the solid-state—to be scrutinized in detail.

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

2014-11-13T23:59:59.000Z

91

Spicing up continuum solvation models with SaLSA: the spherically-averaged liquid susceptibility ansatz  

E-Print Network (OSTI)

Continuum solvation models enable electronic structure calculations of systems in liquid environments, but because of the large number of empirical parameters, they are limited to the class of systems in their fit set (typically organic molecules). Here, we derive a solvation model with no empirical parameters for the dielectric response by taking the linear response limit of a classical density functional for molecular liquids. This model directly incorporates the nonlocal dielectric response of the liquid using an angular momentum expansion, and with a single fit parameter for dispersion contributions it predicts solvation energies of neutral molecules with an RMS error of 1.3 kcal/mol in water and 0.8 kcal/mol in chloroform and carbon tetrachloride. We show that this model is more accurate for strongly polar and charged systems than previous solvation models because of the parameter-free electric response, and demonstrate its suitability for ab initio solvation, including self-consistent solvation in quant...

Sundararaman, Ravishankar; Letchworth-Weaver, Kendra; Arias, T A

2014-01-01T23:59:59.000Z

92

Solvation Sphere of I- and Br- in Water  

SciTech Connect

The solvation sphere of halides in water has been investigated using a combination of extended x-ray absorption fine structure (EXAFS) and x-ray absorption near-edge structure (XANES) analysis techniques. The results have indicated that I- and Br- both have an asymmetric, 8 water molecule primary solvation spheres. These spheres are identical, with the Br{sup -} sphere about .3 {angstrom} smaller than the I{sup -} sphere. This study utilized near-edge analysis to supplement EXAFS analysis which suffers from signal dampening/broadening due to thermal noise. This paper has reported on the solvation first sphere of I{sup -} and Br{sup -} in water. Using EXAFS and XANES analysis, strong models which describe the geometric configuration of water molecules coordinated to a central anion have been developed. The combination of these techniques has provided us with a more substantiated argument than relying solely on one or the other. An important finding of this study is that the size of the anion plays a smaller role than previously assumed in determining the number of coordinating water molecules Further experimental and theoretical investigation is required to understand why the size of the anion plays a minor role in determining the number of water molecules bound.

Not Available

2011-06-22T23:59:59.000Z

93

Capturing inhomogeneous broadening of the -CN stretch vibration in a Langmuir monolayer with high-resolution spectra and ultrafast vibrational dynamics in sum-frequency generation vibrational spectroscopy (SFG-VS)  

SciTech Connect

Even though in principle the frequency-domain and time-domain spectroscopic measurement should generate identical information for a given molecular system, inhomogeneous character of surface vibrations in the sum-frequency generation vibrational spectroscopy (SFG-VS) studies has only been studied with the time-domain SFGVS by mapping the decay of the vibrational polarization using ultrafast lasers, due to the lack of SFG vibrational spectra with high enough spectral resolution and accurate enough line shape. Here with recently developed high-resolution broadband SFG-VS (HR-BB-SFG-VS) we show that the inhomogeneous line shape can be obtained in the frequency-domain, for the anchoring CN stretch of the 4-n-octyl-4'-cyanobiphenyl (8CB) Langmuir monolayer at the air-water interface, and that an excellent agreement with the time-domain SFG free-induction-decay (FID) results can be established. We found that the 8CB CN stretch spectrum consists of a single peak centered at 2234.00 + * 0.01 cm-1 with a total line width of 10.9 + - 0.3 cm-1 at half maximum. The Lorentzian contribution accounts only for 4:7 + -0:4 cm-1 to this width and the Gaussian (inhomogeneous) broadening for as much as 8:1+*0:2 cm-1. Polarization analysis of the -CN spectra showed that the -CN group is tilted 57 + - 2 degrees from the surface normal. The large heterogeneity in the -CN spectrum is tentatively attributed to the -CN group interactions with the interfacial water molecules penetrated/accomodated into the 8CB monolayer, a unique phenomenon for the nCB Langmuir monolayers reported previously.

Velarde Ruiz Esparza, Luis A.; Wang, Hongfei

2013-08-28T23:59:59.000Z

94

Photonic spike processing: ultrafast laser neurons and an integrated photonic network  

E-Print Network (OSTI)

The marriage of two vibrant fields---photonics and neuromorphic processing---is fundamentally enabled by the strong analogies within the underlying physics between the dynamics of biological neurons and lasers, both of which can be understood within the framework of nonlinear dynamical systems theory. Whereas neuromorphic engineering exploits the biophysics of neuronal computation algorithms to provide a wide range of computing and signal processing applications, photonics offer an alternative approach to neuromorphic systems by exploiting the high speed, high bandwidth, and low crosstalk available to photonic interconnects which potentially grants the capacity for complex, ultrafast categorization and decision-making. Here we highlight some recent progress on this exciting field.

Shastri, Bhavin J; Nahmias, Mitchell A; Prucnal, Paul R

2014-01-01T23:59:59.000Z

95

Laser cooling with ultrafast pulse trains  

E-Print Network (OSTI)

We propose a new laser cooling method for atomic species whose level structure makes traditional laser cooling difficult. For instance, laser cooling of hydrogen requires vacuum-ultraviolet laser light, while multielectron atoms need laser light at many widely separated frequencies. These restrictions can be eased by laser cooling on two-photon transitions with ultrafast pulse trains. Laser cooling of hydrogen, antihydrogen, and carbon appears feasible, and extension of the technique to molecules may be possible.

David Kielpinski

2003-06-14T23:59:59.000Z

96

The nature and role of bridged carbonyl intermediates in the ultrafast photo-induced rearrangement of Ru3(CO)12.  

E-Print Network (OSTI)

Unsol. a THF b THF b Unsolv. Propane Unsolv. Unsolv. ProaneI, unsolvated (b) I, Propane solvated (c) I, THF solvated (ax (a) II ax (b) unsolvated Propane solvated II ax (c) THF

Glascoe, Elizabeth A.; Kling, Matthias F.; Shanoski, Jennifer E.; Harris, Charles B.

2005-01-01T23:59:59.000Z

97

Optical coherence and beamspread in ultrafast-laser pulsetrain-burst hole drilling  

E-Print Network (OSTI)

of microfluidics, fuel injectors, etc.). Ultrafast lasers do a particularly good job for many special materials

Marjoribanks, Robin S.

98

Single-shot spectroscopy of solid-state photoinduced dynamics far from equilibrium  

E-Print Network (OSTI)

Ultrafast single-shot spectroscopy was developed and improved as a method to observe photoinduced dynamics far from equilibrium. The method was then employed to illuminate material dynamics in platinum-halide quasi-one-dimensional ...

Wolfson, Johanna Wendlandt

2013-01-01T23:59:59.000Z

99

Membrane formation by preferential solvation of ions in mixture of water, 3-methylpyridine, and sodium tetraphenylborate  

SciTech Connect

The structure and dynamics of a ternary system composed of deuterium oxide (D{sub 2}O), 3-methylpyridine (3MP), and sodium tetraphenylborate (NaBPh{sub 4}) are investigated by means of small-angle neutron scattering (SANS) and neutron spin echo (NSE) techniques. In the SANS experiments, a structural phase transition is confirmed between a disordered-phase and an ordered-lamellar-phase upon variation of the composition and/or temperature of the mixture. The characteristic lengths of the structures is on the sub-micrometer scale. A dispersion relation of the structure is measured through NSE experiments, which shows that the relaxation rate follows a cubic relation with momentum transfer. This implies that the dynamics of the system are determined predominantly by membrane fluctuations. The present results indicate that 3MP-rich domains are microscopically separated from bulk water in the presence of NaBPh{sub 4}, and that the layers behave as membranes. These results are interpreted that preferential solvation of salt in each solvent induces a microphase separation between the solvents, and the periodic structure of 3MP-rich domains is stabilized by the long-range electrostatic interaction arising from Na{sup +} ions in D{sub 2}O-rich domains.

Sadakane, Koichiro, E-mail: sadakane@fc.ritsumei.ac.jp [Department of Physics, Ritsumeikan University, Noji-Higashi 1-1-1, Kusatsu 525-8577 (Japan)] [Department of Physics, Ritsumeikan University, Noji-Higashi 1-1-1, Kusatsu 525-8577 (Japan); Nagao, Michihiro [NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899-6102 (United States) [NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899-6102 (United States); Center for Exploration of Energy and Matter, Indiana University, Bloomington, Indiana 47408-1398 (United States); Endo, Hitoshi; Seto, Hideki [KENS and CMRC, Institute of Materials Structure Science, High Energy Accelerator Research Organization, Tsukuba 305-0801 (Japan)] [KENS and CMRC, Institute of Materials Structure Science, High Energy Accelerator Research Organization, Tsukuba 305-0801 (Japan)

2013-12-21T23:59:59.000Z

100

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

SciTech Connect

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.

Thyrrestrup, Henri, E-mail: h.t.nielsen@utwente.nl; Yüce, Emre; Ctistis, Georgios; Vos, Willem L. [Complex Photonic Systems (COPS), MESA Institute for Nanotechnology, University of Twente, 7500 AE Enschede (Netherlands); Claudon, Julien; Gérard, Jean-Michel, E-mail: jean-michel.gerard@cea.fr [University Grenoble Alpes, INAC-SP2M, Nanophysics and Semiconductors Lab, F-38000 Grenoble (France); CEA, INAC-SP2M, Nanophysics and Semiconductors Lab, F-38000 Grenoble (France)

2014-09-15T23:59:59.000Z

Note: This page contains sample records for the topic "ultrafast solvation dynamics" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


101

Ultrafast magneto-photocurrents in GaAs: Separation of surface and bulk contributions  

E-Print Network (OSTI)

We induce ultrafast magneto-photocurrents in a GaAs crystal employing interband excitation with femtosecond laser pulses at room temperature and non-invasively separate surface and bulk contributions to the overall current response. The separation between the different symmetry contributions is achieved by measuring the simultaneously emitted terahertz radiation for different sample orientations. Excitation intensity and photon energy dependences of the magneto-photocurrents for linearly and circularly polarized excitations reveal an involvement of different microscopic origins, one of which we believe is the inverse Spin-Hall effect. Our experiments are important for a better understanding of the complex momentum-space carrier dynamics in magnetic fields.

Schmidt, Christian B; Tarasenko, Sergey A; Bieler, Mark

2015-01-01T23:59:59.000Z

102

Apparatus and method for characterizing ultrafast polarization varying optical pulses  

DOE Patents (OSTI)

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.

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

1999-08-10T23:59:59.000Z

103

A Source for Ultrafast Continuum Infrared and Terahertz Radiation  

E-Print Network (OSTI)

A compact and stable method for generating high-intensity linearly polarized continuum mid-IR and terahertz light using ultrafast femtosecond (fs) laser pulses is demonstrated. Continuous light generation from <400cm?1 ...

Petersen, Poul B.

104

Ultrafast Biodiesel Production Using Ultrasound in Batch and Continuous Reactors  

Science Journals Connector (OSTI)

Ultrafast Biodiesel Production Using Ultrasound in Batch and Continuous Reactors ... Amongst many resources, availability and cost economy are the major factors affecting the large scale prodn. of the biodiesels. ...

D. C. Boffito; S. Mansi; J.-M. Leveque; C. Pirola; C. L. Bianchi; G. S. Patience

2013-08-23T23:59:59.000Z

105

Weighted-density functionals for cavity formation and dispersion energies in continuum solvation models  

E-Print Network (OSTI)

Continuum solvation models enable efficient first principles calculations of chemical reactions in solution, but require extensive parametrization and fitting for each solvent and class of solute systems. Here, we examine the assumptions of continuum solvation models in detail and replace empirical terms with physical models in order to construct a minimally-empirical solvation model. Specifically, we derive solvent radii from the nonlocal dielectric response of the solvent from ab initio calculations, construct a closed-form and parameter-free weighted-density approximation for the free energy of the cavity formation, and employ a pair-potential approximation for the dispersion energy. We show that the resulting model with a single solvent-independent parameter: the electron density threshold ($n_c$), and a single solvent-dependent parameter: the dispersion scale factor ($s_6$), reproduces solvation energies of organic molecules in water, chloroform and carbon tetrachloride with RMS errors of 1.1, 0.6 and 0....

Sundararaman, Ravishankar; Arias, T A

2014-01-01T23:59:59.000Z

106

Ultrafast and quantitative X-tomography and simulation of hollow-cone gasoline direct-injection sprays.  

SciTech Connect

Gasoline direct injection (GDI) has the potential to greatly improve internal combustion engine performance through precise control of the injection rate, timing, and combustion of the fuel. A thorough characterization of the hydrodynamics of fuel injection has to come from a precise, quantitative analysis of the sprays, especially in the near-nozzle region. A lack of knowledge of the fuel-spray dynamics has severely limited computational modeling of the sprays and design of improved injection systems. Previously, the structure and dynamics of highly transient fuel sprays have never been visualized or reconstructed in three dimensions (3D) due to numerous technical difficulties. By using an ultrafast x-ray detector and intense monochromatic x-ray beams from synchrotron radiation, the fine structures and dynamics of 1-ms GDI fuel sprays from an outwardly opening nozzle were elucidated by a newly developed, ultrafast, microsecond computed microtomography (CT) technique. In a time-resolved manner, many detailed features associated with the transient fuel flows are readily observable in the quantitatively reconstructed 3D fuel spray density distribution as a result of the quantitative CT technique. More importantly, a computational fluid dynamics (CFD) simulation based on the Taylor analogy breakup (TAB) model has also been performed using the boundary and initial conditions obtained from the experiment data. The experimental and numerical results are in good agreement quantitatively. These results not only reveal the characteristics of the GDI fuel sprays with unprecedented detail, but will also facilitate realistic computational fluid dynamic simulations in highly transient, multiphase systems.

Liu, X.; Im, K-S; Wang, Y.; Wang, J.; Tate, M.W.; Ercan, A.; Schuette, D.R.; Gruner, S.M. (X-Ray Science Division); (Cornell Univ.)

2007-01-01T23:59:59.000Z

107

Molecular dynamics study of aqueous solvation dynamics following OClO photoexcitation  

E-Print Network (OSTI)

,5 with subsequent internal conversion from this state to lower-energy excited states re- sulting in photoproduct, respectively.23 Current interest in OClO photochemis- try involves understanding the factors responsible

108

Optimization of the GB/SA Solvation Model for Predicting the Structure of Surface Loops in Proteins  

E-Print Network (OSTI)

Optimization of the GB/SA Solvation Model for Predicting the Structure of Surface Loops in ProteinsVed: October 10, 2005; In Final Form: December 1, 2005 Implicit solvation models are commonly optimized the force field is sometimes not considered. In previous studies, we have developed an optimization

Meirovitch, Hagai

109

Optical Damage Threshold of Silicon for Ultrafast Infrared Pulses  

SciTech Connect

While silicon has several properties making it an attractive material for structure-based laser-driven acceleration, its optical damage threshold, a key parameter for high-gradient acceleration, has been unknown. Here we present measurements of the optical damage threshold of crystalline silicon for ultrafast pulses in the mid-infrared. The wavelengths tested span a range from the telecommunications band at 1550 nm extending longer toward the two-photon absorption threshold at around 2200 nm. We discuss the prevailing theories of ultrafast optical breakdown, describe the experimental setup and preliminary results, and propose a relevant performance parameter for candidate accelerator structures.

Cowan, B.; /SLAC

2006-09-07T23:59:59.000Z

110

Solvation of the Fluorine Containing Anions and Their Lithium Salts in Propylene Carbonate and Dimethoxyethane  

E-Print Network (OSTI)

Electrolyte solutions based on the propylene carbonate (PC)-dimethoxyethane (DME) mixtures are of significant importance and urgency due to emergence of lithium-ion batteries. Solvation and coordination of the lithium cation in these systems have been recently attended in detail. However, analogous information concerning anions (tetrafluoroborate, hexafluorophosphate) is still missed. This work reports PM7-MD simulations (electronic-structure level of description) to include finite-temperature effects on the anion solvation regularities in the PC-DME mixture. The reported result evidences that the anions appear weakly solvated. This observation is linked to the absence of suitable coordination sites in the solvent molecules. In the concentrated electrolyte solutions, both BF4 and PF6 prefer to exist as neutral ion pairs (LiBF4, LiPF6).

Chaban, Vitaly

2015-01-01T23:59:59.000Z

111

The charge-asymmetric nonlocally-determined local-electric (CANDLE) solvation model  

E-Print Network (OSTI)

Many important applications of electronic structure methods involve molecules or solid surfaces in a solvent medium. Since explicit treatment of the solvent in such methods is usually not practical, calculations often employ continuum solvation models to approximate the effect of the solvent. Previous solvation models either involve a parametrization based on atomic radii, which limits the class of applicable solutes, or based on solute electron density, which is more general but less accurate, especially for charged systems. We develop an accurate and general solvation model that includes a cavity that is a nonlocal functional of both solute electron density and potential, local dielectric response on this nonlocally-determined cavity, and nonlocal approximations to the cavity-formation and dispersion energies. The dependence of the cavity on the solute potential enables an explicit treatment of the solvent charge asymmetry. With only three parameters per solvent, this `CANDLE' model simultaneously reproduce...

Sundararaman, Ravishankar

2014-01-01T23:59:59.000Z

112

Ultrafast dynamics of photoinduced processes at surfaces and interfaces  

E-Print Network (OSTI)

, Oleg V. Prezhdo6 1 Fachbereich Physik, Freie Universit¨at Berlin, Germany 2 Fachbereich Physik, Philipps-Universit¨at, Marburg, Germany 3 Institut f¨ur Chemie, Universit¨at Potsdam, Germany 4 Hahn-Meitner-Institut, Berlin, Germany 5 Institut f¨ur Physik, Humboldt Universit¨at zu Berlin, Germany 6 University

113

Ultrafast optical studies of electronic dynamics in semiconductors  

E-Print Network (OSTI)

pump-probe technique is discussed, which can be used to study carrier diffusion, and results are presented on GaAs, graphene, Si/SiGe quantum wells and single walled carbon nanotubes. Next, a quantum interference and control technique and a differential...

Ruzicka, Brian Andrew

2012-05-31T23:59:59.000Z

114

Evidence for Conical Intersection Dynamics Mediating Ultrafast Singlet Exciton Fission  

E-Print Network (OSTI)

and highly efficient. For instance, thin films of pentacene and TIPS-pentacene exhibit triplet formation with a time constant of 80 fs and yields of 200%2,3. Current interest in this phenomenon is driven by its potential to circumvent the Shockley... -Queisser limit for single-junction solar cells. By converting high-energy photons into two low-energy excited states, singlet fission offers a means to overcome thermalisation losses. Devices based on pentacene, a fission sensitiser, have demonstrated external...

Musser, Andrew J.; Liebel, Matz; Schnedermann, Christoph; Wende, Torsten; Kehoe, Tom B.; Rao, Akshay; Kukura, Philipp

2015-01-01T23:59:59.000Z

115

Joint density-functional theory for electronic structure of solvated systems  

E-Print Network (OSTI)

We introduce a new form of density functional theory for the {\\em ab initio} description of electronic systems in contact with a molecular liquid environment. This theory rigorously joins an electron density-functional for the electrons of a solute with a classical density-functional theory for the liquid into a single variational principle for the free energy of the combined system. A simple approximate functional predicts, without any fitting of parameters to solvation data, solvation energies as well as state-of-the-art quantum-chemical cavity approaches, which require such fitting.

Sahak Petrosyan; Jean-Francois Briere; David Roundy; T. A. Arias

2007-02-09T23:59:59.000Z

116

Ultrafast laser induced breakdown spectroscopy of electrode/electrolyte  

NLE Websites -- All DOE Office Websites (Extended Search)

Ultrafast laser induced breakdown spectroscopy of electrode/electrolyte Ultrafast laser induced breakdown spectroscopy of electrode/electrolyte interfaces Title Ultrafast laser induced breakdown spectroscopy of electrode/electrolyte interfaces Publication Type Journal Article Year of Publication 2012 Authors Zormpa, Vasileia, Jaroslaw Syzdek, Xianglei Mao, Richard E. Russo, and Robert Kostecki Journal Applied Physics Letters Volume 100 Issue 23 Date Published 05-2012 ISSN 0003-6951 Keywords electrochemical electrodes, graphite, high-speed optical techniques, laser beam effects, organic compounds, pyrolysis, solid electrolytes Abstract Direct chemical analysis of electrode/electrolyte interfaces can provide critical information on surface phenomena that define and control the performance of Li-based battery systems. In this work, we introduce the use of ex situ femtosecond laser induced breakdown spectroscopy to probe compositional variations within the solid electrolyte interphase (SEI) layer. Nanometer-scale depth resolution was achieved for elemental and molecular depth profiling of SEI layers formed on highly oriented pyrolytic graphite electrodes in an organic carbonate-based electrolyte. This work demonstrates the unique ability of ultrafast laser spectroscopy as a highly versatile, light element-sensitive technique for direct chemical analysis of interfacial layers in electrochemical energy storage systems.

117

Ultrafast Digital Electronics: Optimizing the speed of a  

E-Print Network (OSTI)

Ultrafast Digital Electronics: Optimizing the speed of a Josephson junction J. K. Freericks and P of Naval Research Preprint: cond-mat/0001269 J. K. Freericks, Georgetown University, Josephson Junction symmetry (examples include YBCO and BSCCO). J. K. Freericks, Georgetown University, Josephson Junction talk

Freericks, Jim

118

Ultra-Fast Photodiodes for Terahertz Generation E. Rouvalis1  

E-Print Network (OSTI)

Ultra-Fast Photodiodes for Terahertz Generation E. Rouvalis1 , C. C. Renaud1 and A. J. Seeds1 1 Photodiode is realised as a broadband and high-efficiency photomixer while the frequency response advantage-power photomixers is essential. 2. Travelling-Wave Uni-Travelling Carrier Photodiode (TW-UTC-PD). Bandwidth

Haddadi, Hamed

119

Ultrafast Digital Electronics: Optimizing the speed of a  

E-Print Network (OSTI)

Ultrafast Digital Electronics: Optimizing the speed of a Josephson junction J. K. Freericks and P, Georgetown University, Josephson Junction talk, 2000 #12;Josephson Tunnel Junctions · A Superconductor to "punch-through"). J. K. Freericks, Georgetown University, Josephson Junction talk, 2000 S I S I I V V Ic

Freericks, Jim

120

Ultrafast photochemistry of methyl hydroperoxide on ice particles  

E-Print Network (OSTI)

Ultrafast photochemistry of methyl hydroperoxide on ice particles M. A. Kambouresa , S. AOOH, on water clusters produces a surprisingly wide range of products on a subpicosecond time scale | photodissociation Photoinduced processes at surfaces of water or ice are of interest in atmospheric chemistry

Nizkorodov, Sergey

Note: This page contains sample records for the topic "ultrafast solvation dynamics" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


121

Single-molecule orientational wave packet in ultrafast optical polarization  

SciTech Connect

The explicit derivation of the ultrafast optical polarization of a single molecule is presented. It is shown that an orientational wave packet carried by the excited molecular electron can provide a sharp definition for the space configuration of the laser-molecule interaction.

Mainos, C. [Laboratoire de Physique des Lasers, Universite Paris 13 Av. J.B. Clement, 93430 Villetaneuse (France)

2006-09-15T23:59:59.000Z

122

5D Data Storage by Ultrafast Laser Nanostructuring in Glass  

E-Print Network (OSTI)

5D Data Storage by Ultrafast Laser Nanostructuring in Glass Jingyu Zhang* , Mindaugas Gecevicius-assembled form birefringence and retrieved in glass opening the era of unlimited lifetime data storage. © 2013 laser writing in glass were proposed for the polarization multiplexed optical memory, where

Anderson, Jim

123

Ultrafast Control of Magnetism in Ferromagnetic Semiconductors via Photoexcited Transient Carriers  

SciTech Connect

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.

Cotoros, Ingrid A.

2008-12-12T23:59:59.000Z

124

Ultrafast charge separation in organic photovoltaics enhanced by charge delocalization and vibronically hot exciton dissociation  

E-Print Network (OSTI)

In organic photovoltaics, the mechanism by which free electrons and holes are generated overcoming the Coulomb attraction is a currently much debated topic. To elucidate this mechanism at a molecular level, we carried out a combined electronic structure and quantum dynamical analysis that captures the elementary events from the exciton dissociation to the free carrier generation at polymer/fullerene donor-acceptor heterojunctions. Our calculations show that experimentally observed efficient charge separations can be explained by a combination of two effects: First, the delocalization of charges which substantially reduces the Coulomb barrier, and second, the vibronically hot nature of the charge transfer state which promotes charge dissociation beyond the barrier. These effects facilitate an ultrafast charge separation even at low-band-offset heterojunctions.

Tamura, Hiroyuki

2013-01-01T23:59:59.000Z

125

Snapshots of the retarded interaction of charge carriers with ultrafast fluctuations in cuprates  

E-Print Network (OSTI)

One of the pivotal questions in the physics of high-temperature superconductors is whether the low-energy dynamics of the charge carriers is mediated by bosons with a characteristic timescale. This issue has remained elusive since electronic correlations are expected to dramatically speed up the electron-boson scattering processes, confining them to the very femtosecond timescale that is hard to access even with state-of-the-art ultrafast techniques. Here we simultaneously push the time resolution and the frequency range of transient reflectivity measurements up to an unprecedented level that enables us to directly observe the 16 fs build-up of the effective electron-boson interaction in hole-doped copper oxides. This extremely fast timescale is in agreement with numerical calculations based on the t-J model and the repulsive Hubbard model, in which the relaxation of the photo-excited charges is achieved via inelastic scattering with short-range antiferromagnetic excitations.

Conte, S Dal; Golež, D; Mierzejewski, M; Soavi, G; Peli, S; Banfi, F; Ferrini, G; Comin, R; Ludbrook, B M; Chauviere, L; Zhigadlo, N D; Eisaki, H; Greven, M; Lupi, S; Damascelli, A; Brida, D; Capone, M; Bon?a, J; Cerullo, G; Giannetti, C

2015-01-01T23:59:59.000Z

126

An ethanol-solvated centrosymmetric dimer of bismuth(III) and thiosaccharinate resulting from `semicoordination' contacts  

Science Journals Connector (OSTI)

In an ethanol-solvated centrosymmetric dimer of bismuth(III) and thiosaccharinate, the Bi3+ cation is coordinated by three thio­saccharinate ligands, all of them acting as bidentate chelates through the N and exocyclic S atoms (in a 2N,S mode). Centrosymmetric dimers result from the association of molecules via - interactions.

Dennehy, M.

2014-05-28T23:59:59.000Z

127

Solvation Phenomena in Dilute Solutions: Formal, Experimental Evidence, and Modeling Implications  

SciTech Connect

We review the fundamentals underlying a general molecular-based formalism for the microscopic interpretation of the solvation phenomena involving sparingly soluble solutes in compressible media, an approach that hinges around the unambiguous splitting of the species correlation function integrals into short-(finite) and long-ranged (diverging) contributions at infinite dilution, where this condition is taken as the reference system for the derivation of composition expansions. Then, we invoke the formalism (a) to illustrate the well-behaved nature of the solvation contributions to the mechanical partial molecular properties of solutes at infinite dilution, (b) to guide the development of, and provide molecular-based support to, the macroscopic modeling of high-temperature dilute aqueous-electrolyte solutions, (c) to study solvation effects on the kinetic rate constants of reactions in near-critical solvents in an attempt to understand from a microscopic perspective the macroscopic evidence regarding the thermodynamic pressure effects, and (d) to interpret the microscopic mechanism behind synergistic solvation effects involving either co-solutes or co-solvents, and provide a molecular argument on the unsuitability of the van der Waals one-fluid (vdW-1f) mixing rules for the 2 description of weakly attractive solutes in compressible solvents. Finally, we develop thermodynamically consistent perturbation expansions, around the infinite dilution reference, for the species residual properties in binary and ternary mixtures, and discuss the theoretical and modeling implications behind ad hoc first-order truncated expansions.

Chialvo, Ariel A [ORNL

2013-01-01T23:59:59.000Z

128

Polymer–Graphene Nanocomposites as Ultrafast-Charge and -Discharge Cathodes for Rechargeable Lithium Batteries  

Science Journals Connector (OSTI)

Polymer–Graphene Nanocomposites as Ultrafast-Charge and -Discharge Cathodes for Rechargeable Lithium Batteries ... Lithium battery; cathode; polymer; graphene; nanocomposite ...

Zhiping Song; Terrence Xu; Mikhail L. Gordin; Ying-Bing Jiang; In-Tae Bae; Qiangfeng Xiao; Hui Zhan; Jun Liu; Donghai Wang

2012-03-26T23:59:59.000Z

129

Compact ultrafast semiconductor disk laser: targeting GFP based nonlinear applications in living organisms  

Science Journals Connector (OSTI)

We present a portable ultrafast Semiconductor Disk Laser (SDL) (or vertical extended cavity surface emitting laser—VECSELs), to be used for nonlinear microscopy. The SDL is...

Aviles-Espinosa, Rodrigo; Filippidis, George; Hamilton, Craig; Malcolm, Graeme; Weingarten, Kurt J; Südmeyer, Thomas; Barbarin, Yohan; Keller, Ursula; Santos, Susana I C O; Artigas, David; Loza-Alvarez, Pablo

2011-01-01T23:59:59.000Z

130

High-Throughput Microfluidics and Ultrafast Optics for in vivo Compound/Genetic Discoveries  

Science Journals Connector (OSTI)

We developed microfluidic and ultrafast optical technologies that enable high-throughput whole-animal neural regeneration studies. These technologies allow automated and rapid...

Rohde, Chris; Gilleland, Cody; Samara, Chrysanthi; Yanik, Mehmet F

131

E-Print Network 3.0 - all-optical ultrafast muon Sample Search...  

NLE Websites -- All DOE Office Websites (Extended Search)

not been reported because of silicon's weak ultrafast nonlinearity. We have demonstrated intensity Source: Hochberg, Michael - Department of Electrical Engineering, University of...

132

Water dynamics in large and small reverse micelles: From two ensembles to collective behavior  

E-Print Network (OSTI)

Water dynamics in large and small reverse micelles: From two ensembles to collective behavior David July 2009 The dynamics of water in Aerosol-OT reverse micelles are investigated with ultrafast infrared spectroscopy of the hydroxyl stretch. In large reverse micelles, the dynamics of water are separable into two

Fayer, Michael D.

133

A pulsed electron gun for ultrafast electron diffraction at surfaces A. Janzen,a  

E-Print Network (OSTI)

A pulsed electron gun for ultrafast electron diffraction at surfaces A. Janzen,a B. Krenzer, O The construction of a pulsed electron gun for ultrafast reflection high-energy electron diffraction experiments describe the construction of an elec- tron gun used in RHEED experiments at crystal surfaces

von der Linde, D.

134

HARMONIC CASCADE FEL DESIGNS FOR LUX, A FACILTY FOR ULTRAFAST X-RAY SCIENCE  

E-Print Network (OSTI)

-electron laser (FEL) beamlines which use the har- monic cascade approach to produce coherent XUV & soft X-ray for an integrated system of ultrafast x-ray techniques and lasers, using laser-seeded harmonic cascade FEL's, rfHARMONIC CASCADE FEL DESIGNS FOR LUX, A FACILTY FOR ULTRAFAST X-RAY SCIENCE J. Corlett, W. Fawley

Wurtele, Jonathan

135

Hydrogen Bond Migration between Molecular Sites Observed with Ultrafast 2D IR Chemical Exchange Spectroscopy  

E-Print Network (OSTI)

Hydrogen Bond Migration between Molecular Sites Observed with Ultrafast 2D IR Chemical ExchangeVed: January 12, 2010 Hydrogen-bonded complexes between phenol and phenylacetylene are studied using ultrafast hydrogen bonding acceptor sites (phenyl or acetylene) that compete for hydrogen bond donors in solution

Fayer, Michael D.

136

An Ultra-Fast and Provably CMA Resistant Digital Signature Scheme  

E-Print Network (OSTI)

MQQ-SIG An Ultra-Fast and Provably CMA Resistant Digital Signature Scheme Danilo Gligoroski1 , Rune, Macedonia smile@ii.edu.mk Abstract. We present MQQ-SIG, a signature scheme based on "Mul- tivariate: Public Key Cryptography, Ultra-Fast Public Key Cryptog- raphy, Multivariate Quadratic Polynomials

Paris-Sud XI, Université de

137

Ultrafast Laser Diagnostics for Energetic-Material Ignition Mechanisms: Tools for Physics-Based Model Development.  

SciTech Connect

We present the results of an LDRD project to develop diagnostics to perform fundamental measurements of material properties during shock compression of condensed phase materials at micron spatial scales and picosecond time scales. The report is structured into three main chapters, which each focus on a different diagnostic devel opment effort. Direct picosecond laser drive is used to introduce shock waves into thin films of energetic and inert materials. The resulting laser - driven shock properties are probed via Ultrafast Time Domain Interferometry (UTDI), which can additionally be used to generate shock Hugoniot data in tabletop experiments. Stimulated Raman scattering (SRS) is developed as a temperature diagnostic. A transient absorption spectroscopy setup has been developed to probe shock - induced changes during shock compressio n. UTDI results are presented under dynamic, direct - laser - drive conditions and shock Hugoniots are estimated for inert polystyrene samples and for the explosive hexanitroazobenzene, with results from both Sandia and Lawrence Livermore presented here. SRS a nd transient absorption diagnostics are demonstrated on static thin - film samples, and paths forward to dynamic experiments are presented.

Kearney, Sean P.; Jilek, Brook Anton; Kohl, Ian Thomas; Farrow, Darcie; Urayama, Junji

2014-11-01T23:59:59.000Z

138

Report on Ngai et al.: Change of Caged Dynamics at Tg in hydrated proteins found after suppressing the methyl group rotation contribution"  

E-Print Network (OSTI)

neutron scattering data of solvated proteins, the solvent is now restricted to hydration water: The authors belong to the elastic neutron scattering community, which intends to explain protein dynamics of dynamic information. The full dynamic information derivable from neutron scattering experiments

Doster, Wolfgang

139

Optical Damage Threshold of Silicon for Ultrafast Infrared Pulses  

SciTech Connect

We present measurements of the optical damage threshold of crystalline silicon in air for ultrafast pulses in the near infrared. The wavelengths tested span a range from the telecommunications band at 1550 nm, extending to 2260 nm. We discuss the motivation for the measurements and give theoretical context. We then describe the experimental setup, diagnostics, and procedure. The results show a breakdown threshold of 0.2J/cm{sup 2} at 1550 nm and 1.06 ps FWHM pulse duration, and a weak dependence on wavelength.

Cowan, Benjamin M.; /Tech-X, Boulder /SLAC

2007-11-28T23:59:59.000Z

140

Rise Time Measurement for Ultrafast X-Ray Pulses  

DOE Patents (OSTI)

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.

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

2005-04-05T23:59:59.000Z

Note: This page contains sample records for the topic "ultrafast solvation dynamics" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


141

Ultrafast pulsed laser utilizing broad bandwidth laser glass  

DOE Patents (OSTI)

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.

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

1997-09-02T23:59:59.000Z

142

Prospects for all-optical ultrafast muon acceleration  

E-Print Network (OSTI)

A scheme for fast, compact, and controllable acceleration of heavy particles in vacuum has been recently proposed [F. Peano et al., New J. Phys. 10 033028 (2008)], wherein two counterpropagating laser beams with variable frequencies drive a beat-wave structure with variable phase velocity, leading to particle trapping and acceleration. The technique allows for fine control over the energy distribution and the total charge of the accelerated beam, to be obtained via tuning of the frequency variation. Here, the theoretical bases of the acceleration scheme are described, and the possibility of applications to ultrafast muon acceleration and to the prompt extraction of cold-muon beams is discussed.

Peano, F; Mulas, R; Coppa, G; Bingham, R; Silva, L O

2008-01-01T23:59:59.000Z

143

Ab initio study of the structure and dynamics of solvated highly charged metal ions  

E-Print Network (OSTI)

and experimental data. CaCl2 Exp. 22 (650K) (673K) CN OI5.10 : Trajectory of the CaCl2 300K AIMD simulation in which5.11 : Trajectory of the CaCl2 300K AIMD simulation in which

Bogatko, Stuart A.

2008-01-01T23:59:59.000Z

144

Femtosecond Infrared Study of the Dynamics of Solvation and Solvent Caging  

E-Print Network (OSTI)

. Snee, Kenneth T. Kotz, Christine K. Payne, and Charles B. Harris* Contribution from the Department correspondence should be addressed. E-mail: harris@ socrates.berkeley.edu. Present address: Harvard University. Principals and Applications of Homo- geneous Catalysis; John Wiley & Sons: New York, 1980. (2) Meyer, T. J

Harris, Charles B.

145

Dynamic  

Office of Legacy Management (LM)

Dynamic 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 OIL SHALE MINE A T RIFLE, COLORADO, T O THE, RULISON EVENT ORDER FROM CFSTl A S ~ B ~ &J C / This page intentionally left blank CONTENTS Page . . . . . . . . . . . . . . . . . . . . . . . . . H i s t o r i c . a l Des c r i p t i o n 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Summary 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Introduction 3

146

UPGRADING METHANE USING ULTRA-FAST THERMAL SWING ADSORPTION  

SciTech Connect

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.

Anna Lee Tonkovich

2004-01-01T23:59:59.000Z

147

Development and application of QM/MM methods to study the solvation effects and surfaces  

SciTech Connect

Quantum mechanical (QM) calculations have the advantage of attaining high-level accuracy, however QM calculations become computationally inefficient as the size of the system grows. Solving complex molecular problems on large systems and ensembles by using quantum mechanics still poses a challenge in terms of the computational cost. Methods that are based on classical mechanics are an inexpensive alternative, but they lack accuracy. A good trade off between accuracy and efficiency is achieved by combining QM methods with molecular mechanics (MM) methods to use the robustness of the QM methods in terms of accuracy and the MM methods to minimize the computational cost. Two types of QM combined with MM (QM/MM) methods are the main focus of the present dissertation: the application and development of QM/MM methods for solvation studies and reactions on the Si(100) surface. The solvation studies were performed using a discreet solvation model that is largely based on first principles called the effective fragment potential method (EFP). The main idea of combining the EFP method with quantum mechanics is to accurately treat the solute-solvent and solvent-solvent interactions, such as electrostatic, polarization, dispersion and charge transfer, that are important in correctly calculating solvent effects on systems of interest. A second QM/MM method called SIMOMM (surface integrated molecular orbital molecular mechanics) is a hybrid QM/MM embedded cluster model that mimics the real surface.3 This method was employed to calculate the potential energy surfaces for reactions of atomic O on the Si(100) surface. The hybrid QM/MM method is a computationally inexpensive approach for studying reactions on larger surfaces in a reasonably accurate and efficient manner. This thesis is comprised of four chapters: Chapter 1 describes the general overview and motivation of the dissertation and gives a broad background of the computational methods that have been employed in this work. Chapter 2 illustrates the methodology of the interface of the EFP method with the configuration interaction with single excitations (CIS) method to study solvent effects in excited states. Chapter 3 discusses the study of the adiabatic electron affinity of the hydroxyl radical in aqueous solution and in micro-solvated clusters using a QM/EFP method. Chapter 4 describes the study of etching and diffusion of oxygen atom on a reconstructed Si(100)-2 x 1 surface using a hybrid QM/MM embedded cluster model (SIMOMM). Chapter 4 elucidates the application of the EFP method towards the understanding of the aqueous ionization potential of Na atom. Finally, a general conclusion of this dissertation work and prospective future direction are presented in Chapter 6.

Dibya, Pooja Arora

2010-05-16T23:59:59.000Z

148

Melting processes of oligomeric ? and ? isotactic polypropylene crystals at ultrafast heating rates  

SciTech Connect

The melting behaviors of ? (stable) and ? (metastable) isotactic polypropylene (iPP) crystals at ultrafast heating rates are simulated with atomistic molecular dynamics method. Quantitative information about the melting processes of ?- and ?-iPP crystals at atomistic level is achieved. The result shows that the melting process starts from the interfaces of lamellar crystal through random dislocation of iPP chains along the perpendicular direction of lamellar crystal structure. In the melting process, the lamellar crystal gradually expands but the corresponding thickness decreases. The analysis shows that the system expansion lags behind the crystallinity decreasing and the lagging extents for ?- and ?-iPP are significantly different. The apparent melting points of ?- and ?-iPP crystals rise with the increase of the heating rate and lamellar crystal thickness. The apparent melting point of ?-iPP crystal is always higher than that of ?-iPP at differently heating rates. Applying the Gibbs-Thomson rule and the scaling property of the melting kinetics, the equilibrium melting points of perfect ?- and ?-iPP crystals are finally predicted and it shows a good agreement with experimental result.

Ji, Xiaojing [School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072 (China)] [School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072 (China); He, Xuehao, E-mail: xhhe@tju.edu.cn, E-mail: scjiang@tju.edu.cn [Department of Chemistry, School of Science, Tianjin University, and Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin 300072 (China)] [Department of Chemistry, School of Science, Tianjin University, and Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin 300072 (China); Jiang, Shichun, E-mail: xhhe@tju.edu.cn, E-mail: scjiang@tju.edu.cn [School of Material, Tianjin University, Tianjin 300072 (China)] [School of Material, Tianjin University, Tianjin 300072 (China)

2014-02-07T23:59:59.000Z

149

Nonadiabatic Molecular Dynamics Simulations of the Energy Transfer between Building Blocks in a Phenylene Ethynylene Dendrimer  

E-Print Network (OSTI)

Nonadiabatic Molecular Dynamics Simulations of the Energy Transfer between Building Blocks E. Roitberg*, UniVersidad Nacional de Quilmes, Roque Saenz Pen~a 352, B1876BXD Bernal, Argentina, 2009 The ultrafast dynamics of electronic and vibrational energy transfer between two- and three

Tretiak, Sergei

150

Electron Pulse Compression with a Practical Reflectron Design for Ultrafast Electron Diffraction  

E-Print Network (OSTI)

Ultrafast electron diffraction (UED) is a powerful method for studying time-resolved structural changes. Currently, space-charge-induced temporal broadening prevents obtaining high-brightness electron pulses with sub-100 ...

Wang, Yihua

151

Ultrafast all-optical switching with low saturation energy via intersubband transitions in  

E-Print Network (OSTI)

, and H. Ishikawa, "Low-saturation-energy-driven ultrafast all-optical switching operation in (CdS. Cho, "Intersubband absorption at ~ 1.55 m in well- and modulation-doped GaN/AlGaN multiple quantum

Paiella, Roberto

152

Are water simulation models consistent with steady-state and ultrafast vibrational spectroscopy experiments?  

E-Print Network (OSTI)

Are water simulation models consistent with steady-state and ultrafast vibrational spectroscopy, United States b Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139, United States c Department of Chemistry, Stanford University, Stanford, CA 94305, United States Received

Fayer, Michael D.

153

Collective Hydrogen Bond Reorganization in Water Studied with Temperature-Dependent Ultrafast Infrared Spectroscopy  

E-Print Network (OSTI)

We use temperature-dependent ultrafast infrared spectroscopy of dilute HOD in H2O to study the picosecond reorganization of the hydrogen bond network of liquid water. Temperature-dependent two-dimensional infrared (2D IR), ...

Nicodemus, Rebecca A.

154

Ultrafast laser inscription of bistable and reversible waveguides in strontium barium niobate crystals  

E-Print Network (OSTI)

Ultrafast laser inscription of bistable and reversible waveguides in strontium barium niobate optical channel waveguides in strontium barium niobate nonlinear ferroelectric crystals by direct for the fabrication of optical buried waveguides. This would be especially relevant in the ferroelectric strontium

155

Flexible graphene-based lithium ion batteries with ultrafast charge and discharge rates  

Science Journals Connector (OSTI)

Flexible graphene-based lithium ion batteries with ultrafast charge and...and flexible lithium ion battery made from graphene foam, a three-dimensional...and flexible lithium ion battery made from graphene foam, a three-dimensional...

Na Li; Zongping Chen; Wencai Ren; Feng Li; Hui-Ming Cheng

2012-01-01T23:59:59.000Z

156

Studies of third-order nonlinearities in materials and devices for ultrafast lasers  

E-Print Network (OSTI)

Recent developments in telecommunications, frequency metrology, and medical imaging have motivated research in ultrafast optics. Demand exists for broadband components and sources as well as highly nonlinear fibers and ...

Gopinath, Juliet Tara, 1976-

2005-01-01T23:59:59.000Z

157

Molecular Dynamics of Methanol Monocation (CH3OH+ ) in Strong  

E-Print Network (OSTI)

ultrafast hydrogen migration.7,8 The 38 fs 800 nm pump pulse produced methanol monocation, and a probe pulseMolecular Dynamics of Methanol Monocation (CH3OH+ ) in Strong Laser Fields Bishnu Thapa and H surfaces of methanol neutral, monocation, and singlet and triplet dication were explored using the CBS

Schlegel, H. Bernhard

158

Dynamics  

NLE Websites -- All DOE Office Websites (Extended Search)

Hydration Hydration Water on Rutile Studied by Backscattering Neutron Spectroscopy and Molecular Dynamics Simulation E. Mamontov,* ,† D. J. Wesolowski, ‡ L. Vlcek, § P. T. Cummings, §,| J. Rosenqvist, ‡ W. Wang, ⊥ and D. R. Cole ‡ Spallation Neutron Source, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6473, Chemical Sciences DiVision, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6110, Department of Chemical Engineering, Vanderbilt UniVersity, NashVille, Tennessee 37235-1604, Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6496, and EnVironmental Sciences DiVision, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6036 ReceiVed: December 20, 2007; ReVised Manuscript ReceiVed: June 4, 2008 The high energy resolution, coupled with the wide dynamic range, of the new backscattering

159

Accuracy of exchange-correlation functionals and effect of solvation on the surface energy of copper  

Science Journals Connector (OSTI)

Surface energies are important for predicting the shapes of nanocrystals and describing the faceting and roughening of surfaces. Copper surfaces are of particular interest in recent years since they are the preferred surfaces for growing graphene using chemical vapor deposition. In this study we calculate the surface energies of copper for the three low-index facets (111), (100), and (110) and one high-index facet, (210), using density-functional theory with both the local-density approximation and various parametrizations of the generalized-gradient approximation to the exchange-correlation functional. To assess the accuracy of the different functionals, we obtain the average surface energies of an isotropic crystal using a broken-bond model. We use this method, which can be generalized to other crystal structures, to compare calculated surface energies to experimental surface energies for fcc crystals. We find that the recent exchange-correlation functionals AM05 and PBEsol are the most accurate functionals for calculating the surface energies of copper. To determine how solvents affect the surface energies of copper, we perform calculations using a continuum solvation model. We find that aqueous solvation changes the overall magnitude of the surface energies only slightly but leads to more isotropic surface energies.

Matthew Fishman; Houlong L. Zhuang; Kiran Mathew; William Dirschka; Richard G. Hennig

2013-06-03T23:59:59.000Z

160

Solvated Electrons in Very Small Clusters of Polar Molecules: (HF)(3)(-): art. no. 143001  

SciTech Connect

A cluster of polar molecules can host an excess electron in at least two ways. First, the excess electron can be tethered to the cluster by its interaction with the cluster?s dipole moment. , Second, the electron can localize inside the cluster, bulk analogs being the hydrated and ammoniated electrons. - While the structural reorganization of the cluster, due to attachment of an excess electron, is typically small for dipole-bound electrons (dbe), it is usually quite significant for''solvated electrons'' (se), since the solvation occurs at the expense of breaking of pre-existing hydrogen bonds. The se structures, however, provide more contact interactions between the polar molecules and the excess electron. For these reasons, it is often assumed that dbe's dominate for small polar clusters, whereas large clusters form se's. Here we show that dbe's and se's coexist in as small a cluster as (HF)3-. The stability of these anions with respect to the neutral cluster results not only from the excess electron binding energy but also from favorable entropic effects, which reflect the greater ''floppiness'' of the anionic structures.

Gutowski, Maciej S. (BATTELLE (PACIFIC NW LAB)); Hall, C (Arizona, University Of); Adamowicz, L (Arizona, University Of); Hendricks, J.H. (Johns Hopkins Univ); De Clercq, Helen (Howard University); Lyapustina, S.A. (Johns Hopkins Univ); Nilles, J.M. (Johns Hopkins Univ); Xu, S.J. (Johns Hopkins Univ); Bowen Jr., K.H. (Johns Hopkins Univ)

2001-12-01T23:59:59.000Z

Note: This page contains sample records for the topic "ultrafast solvation dynamics" from the National Library of EnergyBeta (NLEBeta).
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161

Final Progress Report for Linking Ion Solvation and Lithium Battery Electrolyte Properties  

SciTech Connect

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 electrolyte physicochemical and electrochemical properties which govern (in part) battery performance. Lithium battery electrolytes remain a poorly understood and hardly studied topic relative to the research devoted to battery electrodes. This is due to the fact that it is the electrodes which determine the energy (capacity) of the battery. The electrolyte, however, plays a crucial role in the practical energy density, power, low and/or high temperature performance, lifetime, safety, etc. which is achievable. The development within this project of a "looking glass" into the molecular interactions (i.e., solution structure) in bulk electrolytes through a synergistic experimental approach involving three research thrusts complements work by other researchers to optimize multi-solvent electrolytes and efforts to understand/control the electrode-electrolyte interfaces, thereby enabling the rational design of electrolytes for a wide variety of battery chemistries and applications (electrolytes-on-demand). The three research thrusts pursued include: (1) conduction of an in-depth analysis of the thermal phase behavior of diverse solvent-LiX mixtures, (2) exploration of the ionic association/solvate formation behavior of select LiX salts with a wide variety of solvents, and (3) linking structure to properties?determination of electrolyte physicochemical and electrochemical properties for comparison with the ionic association and phase behavior.

Henderson, Wesley

2014-08-29T23:59:59.000Z

162

Potentials of Mean Force With Ab Initio Mixed Hamiltonian Models of Solvation  

SciTech Connect

We give an account of a computationally tractable and efficient procedure for the calculation of potentials of mean force using mixed Hamiltonian models of electronic structure where quantum subsystems are described with computationally intensive ab initio wavefunctions. The mixed Hamiltonian is mapped into an all-classical Hamiltonian that is amenable to a thermodynamic perturbation treatment for the calculation of free energies. A small number of statistically uncorrelated (solute-solvent) configurations are selected from the Monte Carlo random walk generated with the all-classical Hamiltonian approximation. Those are used in the averaging of the free energy using the mixed quantum/classical Hamiltonian. The methodology is illustrated for the micro-solvated SN2 substitution reaction of methyl chloride by hydroxide. We also compare the potential of mean force calculated with the above protocol with an approximate formalism, one in which the potential of mean force calculated with the all-classical Hamiltonian is simply added to the energy of the isolated (non-solvated) solute along the reaction path. Interestingly the latter approach is found to be in semi-quantitative agreement with the full mixed Hamiltonian approximation.

Dupuis, Michel; Schenter, Gregory K.; Garrett, Bruce C.; Arcia, Edgar E.

2003-08-01T23:59:59.000Z

163

A minute-continuous-wave-stabilized picosecond supercontinuum source for ultrafast serial time-encoded amplified microscopy (STEAM)  

Science Journals Connector (OSTI)

A stabilized picosecond supercontinuum source, by a minute continuous-wave trigger, is utilized to improve the ultrafast imaging quality of serial time-encoded amplified microscopy...

Zhang, Chi; Qiu, Yi; Xu, Jianbing; Wong, Kenneth K Y; Tsia, Kevin K

164

Time-Resolved Measurements of Near-Infrared Pulse Induced Ultrafast Optical Modulation of Quantum Cascade Lasers  

Science Journals Connector (OSTI)

We temporally resolve ultrafast modulation of quantum cascade lasers (QCLs) using a near-infrared pump mid-infrared probe technique. We compare interband and intersubband transition...

Cai, Hong; Liu, Sheng; Lalanne, Elaine; Guo, Dingkai; Chen, Xing; Wang, Xiaojun; Choa, Fow-Sen; Johnson, Anthony M

165

Ultrafast transient grating radiation to optical image converter  

DOE Patents (OSTI)

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.

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

2014-11-04T23:59:59.000Z

166

Precise and ultrafast molecular sieving through graphene oxide membranes  

E-Print Network (OSTI)

There has been intense interest in filtration and separation properties of graphene-based materials that can have well-defined nanometer pores and exhibit low frictional water flow inside them. Here we investigate molecular permeation through graphene oxide laminates. They are vacuum-tight in the dry state but, if immersed in water, act as molecular sieves blocking all solutes with hydrated radii larger than 4.5A. Smaller ions permeate through the membranes with little impedance, many orders of magnitude faster than the diffusion mechanism can account for. We explain this behavior by a network of nanocapillaries that open up in the hydrated state and accept only species that fit in. The ultrafast separation of small salts is attributed to an 'ion sponge' effect that results in highly concentrated salt solutions inside graphene capillaries.

R. K. Joshi; P. Carbone; F. C. Wang; V. G. Kravets; Y. Su; I. V. Grigorieva; H. A. Wu; A. K. Geim; R. R. Nair

2014-01-14T23:59:59.000Z

167

A Born-Oppenheimer approximation for path integrals with an application to electron solvation in polarizable fluids  

E-Print Network (OSTI)

A Born-Oppenheimer approximation for path integrals with an application to electron solvation (Received 8 February 1993; accepted 13 April 1993) The Born-Oppenheimer approximation is introduced this to simulations. We devise a new adiabatic expression which we call the free energy Born-Oppenheimer approximation

Berne, Bruce J.

168

J. Am. Chem. SOC.1994,116, 11039-11047 11039 The Brownian Oscillator Model for Solvation Effects in  

E-Print Network (OSTI)

the coupling of the solute's energy levels to the environment has most often been treated throughJ. Am. Chem. SOC.1994,116, 11039-11047 11039 The Brownian Oscillator Model for Solvation Effects the optical band shapes and the nuclear Franck- Condon factor for nonphotochemical electron transfer processes

Mukamel, Shaul

169

Dynamic Transmission Electron Microscopy  

SciTech Connect

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.

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

2012-10-12T23:59:59.000Z

170

Upgrading Methane Using Ultra-Fast Thermal Swing Adsorption  

SciTech Connect

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 technical feasibility and cost of upgrading low-BTU methane streams using ultra-fast thermal swing adsorption (TSA) using Velocys modular microchannel process technology. The objective of Phase II is to demonstrate the process at the bench-scale. Natural gas upgrading systems have six main unit operations: feed compressor, dehydration unit, nitrogen rejection unit, deoxygenator, carbon dioxide scrubber, and a sales compressor. The NRU is the focus of the development program, and a bench-scale demonstration has been initiated. The Velocys NRU system targets producing methane with greater than 96% purity and at least 90% recovery for final commercial operation. A preliminary cost analysis of the methane upgrading system, including the Velocys NRU, suggests that costs below $2.00 per million (MM) BTU methane may be achieved. The cost for a conventional methane upgrading system is well above $2.30 per MM BTU, as benchmarked in an Environmental Protection Agency study. The project is on schedule and on budget. Task 4, a bench-scale demonstration of the ultra-fast TSA system is complete. Rapid thermal swing of an adsorbent bed using microchannels has been successfully demonstrated and the separation of a 70% methane and 30% nitrogen was purified to 92% methane. The bench-scale demonstration unit was small relative to the system dead volume for the initial phase of experiments and a purge step was added to sweep the dead volume prior to desorbing the bed and measuring purity. A technical and economic feasibility assessment was completed in Task 3. The proposed Velocys technology appears feasible for the methane upgrading market. Evaluated categories include adsorbent selection, rapid-cycle valve selection, microchannel manufacturability assessment, and system design and cost. The selected adsorbent, granular microporous carbon from either Barnaby-Sutcliffe or Calgon, experimentally demonstrated sufficient methane capacity under differential temperature at 100 pounds per square inch gauge. Several valve options were identified, including candidates that can operate millions of cycles between refurbishment. The microchannel adsorber and desorber designs were made using internal Velocys manufacturability standards, and the associated costs are acceptable as included with the complete nitrogen rejection unit (NRU) cost projection. A system design and cost estimate was completed for the NRU section of the methane upgrading system. As integrated into the complete system, the cost is in line with the market requirement.

Anna Lee Tonkovich

2005-07-01T23:59:59.000Z

171

Extension - Upgrading Methane Using Ultra-Fast Thermal Swing Adsorption  

SciTech Connect

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.

Anna Lee Tonkovich

2008-08-11T23:59:59.000Z

172

Ultra-Fast Pump-Probe Detection Using Plasmas  

SciTech Connect

The temporal resolution of pump-flash interactions in the femtosecond-attosecond (fs-as) regime is limited by the characteristic time constants of the excited states in the detector material. If the relaxation time constant is appreciably longer that the time interval between the pump and probe signals the response of the detector material to the probe represents a temporal convolution with the pump and probe responses, setting a lower limit on the resolution to which the interval between the two pulses can be measured. In most of the solid state ultrafast detection schemes that are being considered for the ultrashort pulse x-ray sources under current development at SLAC and elsewhere the characteristic time constants are related to the bound states of the atoms comprising the material or to the relaxation times of phase transitions or charge carrier populations of the lattice, setting a probable lower limit on the attainable resolution on the order of {approx}0.1 ps. In this paper we consider a novel detection principle based on the excitation of specially prepared unbound states in an ionized plasma with high pump and probe fields, and estimate its potential for extending the lower limit of resolution into the attosecond (as) regime.

Tatchyn, R.; /SLAC

2006-02-17T23:59:59.000Z

173

A quantum-dynamical theory for nonlinear optical interactions in graphene  

E-Print Network (OSTI)

We use a quantum-dynamical model to investigate the optical response of graphene under low excitation power. Ultrafast carrier relaxation processes, which play an important role for understanding the optical response of graphene, are included phenomenologically into the model. We obtain analytical solutions for the linear and third-order nonlinear optical response of graphene, and four-wave mixing in particular. This theory shows agreement with recently reported experimental data on linear complex optical conductivity and four-wave mixing, providing evidence for ultrafast quantum-dephasing times of approximately 1 fs.

Zheshen Zhang; Paul L. Voss

2011-06-23T23:59:59.000Z

174

Co-nonsolvency of PNiPAM at the transition between solvation mechanisms  

E-Print Network (OSTI)

We investigate the co-nonsolvency of poly-N-isopropyl acrylamide (PNiPAM) in different water-alcohol mixtures and show that this phenomenon is due to two distinct solvation contributions governing the phase behavior of PNiPAM in the water-rich and alcohol-rich regime respectively. While hydrophobic hydration is the predominant contribution governing the phase behavior of PNiPAM in the water-rich regime, the mixing contributions governing the phase behavior of classical polymer solutions determine the phase behavior of PNiPAM in the alcohol-rich regime. This is evidenced by distinct scaling relations denoting the energetic state of the aqueous medium as a key parameter for the phase behavior of PNiPAM in the water-rich regime, while the volume fractions of respectively water, alcohol and PNiPAM become relevant parameters in the alcohol-rich regime. Adding alcohol to water decreases the energetics of the aqueous medium, which gradually suppresses hydrophobic hydration, while adding water to alcohol decreases the solvent quality. Consequently, PNiPAM is insoluble in the intermediate range of solvent composition, where neither hydrophobic hydration nor the mixing contributions prevail. This accounts for the co-nonsolvency phenomenon observed for PNiPAM in water-alcohol mixtures.

Irmgard Bischofberger; Davide C. E. Calzolari; Veronique Trappe

2014-10-28T23:59:59.000Z

175

Laser pulse control of ultrafast heterogeneous electron transfer: A computational study  

E-Print Network (OSTI)

Laser pulse control of ultrafast heterogeneous electron transfer: A computational study Luxia Wang, Germany Received 31 March 2004; accepted 30 July 2004 Laser pulse control of the photoinduced 90 fs charge in which way the charge injection time can be changed by tailored laser pulses. In a second step a pump

Röder, Beate

176

Single ultrafast diffusive conduction based optoelectronic switch for multi-channel operation  

E-Print Network (OSTI)

Single ultrafast diffusive conduction based optoelectronic switch for multi-channel operation Fatih to multi-channel operation, including Green's function diffusive conduction solution and crosstalk conduction based optoelectronic switches that accommodate >100 optical channels (with 2,000mm-2 channel

Miller, David A. B.

177

Ultrafast deflection of spatial solitons in AlxGa1-xAs slab waveguides  

E-Print Network (OSTI)

laser pulse. A separate ultrashort pump pulse is focused onto the top of the waveguide, introducing cladding, both with x=0.24. The pulses used to generate and steer the solitons are obtained from an ultrafast laser system: a 250 kHz optical parametric amplifi

Van Driel, Henry M.

178

Ultrafast Microwave Hydrothermal Synthesis of BiFeO3 Nanoplates Riad Nechache,  

E-Print Network (OSTI)

hydrothermal processes while requiring significantly less time and energy. In addition, we show that microwaveUltrafast Microwave Hydrothermal Synthesis of BiFeO3 Nanoplates Shun Li, Riad Nechache,§ Ivan and very rapid (1­2 min) microwave-assisted hydrothermal approach. We show that the microwave treatment

179

Ultrafast high-pressure AC electro-osmotic pumps for portable biomedical microfluidics  

E-Print Network (OSTI)

Ultrafast high-pressure AC electro-osmotic pumps for portable biomedical microfluidics Chien details the development of an integrated AC electro-osmotic (ACEO) microfluidic pump for dilute (100 mM) biological solutions in separate microfluidic devices, with potential applications in portable

Bazant, Martin Z.

180

Optical Deflection and Temporal Characterization of an Ultrafast Laser-Produced Electron Beam  

E-Print Network (OSTI)

Optical Deflection and Temporal Characterization of an Ultrafast Laser-Produced Electron Beam show that the optical pulse with a0 0:5 imparts momentum to the electron beam, causing it to deflect optically driven x-ray sources based on nonlinear Thomson scattering [3­5]. A finite optical pulse imparts

Umstadter, Donald

Note: This page contains sample records for the topic "ultrafast solvation dynamics" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
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181

Generation of mega-electron-volt electron beams by an ultrafast intense laser pulse  

E-Print Network (OSTI)

Generation of mega-electron-volt electron beams by an ultrafast intense laser pulse Xiaofang Wang filamentation and beam breakup. These results suggest an approach for generating a beam of femtosecond, Me-intensity lasers has made it pos- sible to study extreme physics on a tabletop. Among the studies, the generation

Umstadter, Donald

182

An EXAFS spectroscopic study of solvates of copper(I) and copper(II) in acetonitrile, dimethyl sulfoxide, pyridine, and tetrahydrothiophene solutions and a large-angle X-ray scattering study of the copper(II) acetonitrile solvate in solution  

SciTech Connect

X-ray absorption edge and EXAFS spectra of the acetonitrile, dimethyl sulfoxide, pyridine and tetrahydrothiophene solvated copper(I) ions and the acetonitrile and dimethyl sulfoxide solvated copper(II) ions have been measured in solution. Analysis reveals that the copper(I) solvates are most probably tetrahedral, and the following Cu-solvate bond distances have been found: Cu-N = 1.99(2) [angstrom] in acetonitrile, Cu-O = 2.09(4) [angstrom] in dimethyl sulfoxide, Cu-N = 2.06(1) [angstrom] in pyridine, and Cu-S = 2.30(1) [angstrom] in tetrahydrothiophene. The copper(II) solvates are most probably Jahn-Teller distorted octahedrons, and the following equatorial Cu-solvate bond distances have been found: Cu-N = 1.99(1) [angstrom] in acetonitrile, and Cu-O = 1.98(1) [angstrom] in dimethyl sulfoxide. An 1.0 M solution of copper(II) trifluoromethanesulfonate in acetonitrile has been studied by means of the large-angle X-ray scattering technique, and the following Cu-N and Cu-C distances have been found for the Cu(CH[sub 3]CN)[sub 4][sup 2][sup +] complex: 1.99(1) and 3.12(1) [angstrom], respectively. No solvate molecules in the axial positions could however be seen by any of the technique used. The structure of the tetraaquacopper(I) ion has been assumed to be tetrahedral, and from a correlation between the difference in bond length between the copper(I) and copper(II) solvates and the disproportionation constants of copper(I) in the solvent, the Cu-O bond distance is predicted to be approximately 0.14 [angstrom] longer than the equatorial Cu-O distances in the Jahn-Teller distorted hexaaquacopper(II) complex, thus about 2.13 [angstrom].

Persson, I. (Swedish Univ. of Agricultural Sciences, Uppsala (Sweden)); Penner-Hahn, J.E. (Univ. of Michigan, Ann Arbor (United States) Stanford Univ., CA (United States)); Hodgson, K.O. (Univ. of Michigan, Ann Arbor (United States))

1993-05-26T23:59:59.000Z

183

Ultrafast gigantic photo-response in (EDO-TTF)2PF6 initiated by 10-fs laser pulses  

E-Print Network (OSTI)

Ultrafast gigantic photo-response in (EDO- TTF) 2 PF 6JItatani@lbl.gov Abstract. We photo-exited a charge- orderedfs optical pulses. The photo-induced metallic phase appeared

Itatani, J.

2006-01-01T23:59:59.000Z

184

Ultrafast Photocurrent Measurement of the Escape Time of Electrons and Holes from Carbon Nanotube p-i-n Photodiodes  

E-Print Network (OSTI)

Ultrafast photocurrent measurements are performed on individual carbon nanotube p-i-n photodiodes. The photocurrent response to subpicosecond pulses separated by a variable time delay ?t shows strong photocurrent suppression ...

Gabor, Nathaniel M.

185

Solvated Electron Technology{sup TM}. Non-Thermal Alternative to Waste Incineration  

SciTech Connect

Solvated Electron Technology (SET{sup TM}) is a patented non-thermal alternative to incineration for treating Toxic Substances Control Act (TSCA) and other mixed waste by destroying organic hazardous components. SET{sup TM} is a treatment process that destroys the hazardous components in mixed waste by chemical reduction. The residual material meets land disposal restriction (LDR) and TSCA requirements for disposal. In application, contaminated materials are placed into a treatment cell and mixed with the solvated electron solution. In the case of PCBs or other halogenated contaminants, chemical reactions strip the halogen ions from the chain or aromatic ring producing sodium chloride and high molecular weight hydrocarbons. At the end of the reaction, ammonia within the treatment cell is removed and recycled. The reaction products (such as sodium salts) produced in the process remain with the matrix. The SET{sup TM} process is 99.999% effective in destroying: polychlorinated biphenyls (PCBs); trichloroethane (TCA) and trichloroethene (TCE); dioxins; polycyclic aromatic hydrocarbons (PAHs); benzene, toluene, xylene (BTX); pesticides; fungicides; herbicides; chlorofluorocarbons (CFCs); hydro-chlorofluorocarbons (HCFCs), explosives and chemical-warfare agents; and has successfully destroyed many of the wastes listed in 40 Code of Federal Regulations (CFR) 261. In September 2007, U.S. Environmental Protection Agency (EPA) issued a Research and Development permit for SET for chemical destruction of 'pure' Pyranol, which is 60% PCBs. These tests were completed in November 2007. SET{sup TM} is recognized by EPA as a non-thermal process equivalent to incineration and three SET{sup TM} systems have been permitted by EPA as commercial mobile PCB destruction units. This paper describes in detail the results of select bench-, pilot-, and commercial-scale treatment of hazardous and mixed wastes for EPA, Department of Energy (DOE), and the Department of Defense(DoD), and the applicability of SET{sup TM} to currently problematic waste streams that have very limited treatment alternatives. In summary: SET{sup TM} operates as a non-thermal destruction process under low pressure. The process occurs in a closed system producing no hazardous off-gases and no regulated by-products such as dioxins or furans or their precursors. Advantages of SET{sup TM} include: - Organic contaminants are destroyed, not just removed, diluted or concentrated. - Operates as a closed system - produces no regulated secondary wastes. - Holds an EPA permit for PCB destruction. - Operates at ambient temperatures (70 deg. F). - Portable and sets up quickly in less than 4000 square feet of space. - Scalable to accommodate any size waste stream. - Requires minimal amounts of power, water and infrastructure. - Applicable to heterogeneous waste streams in all phases. The SET{sup TM} process is 99.9999% effective in destroying organic constituents of RCRA and TSCA waste, explosives and chemical-warfare agents; and has successfully destroyed many of the wastes listed in 40 Code of Federal Regulations (CFR) 261. The residual material meets land disposal restriction (LDR) and TSCA requirements for disposal. In November 2007, Commodore completed a treatability study on Pyranol to determine the effectiveness of SET{sup TM} treatment on oil containing 600,000 PPM PCBs. Laboratory results proved destruction of PCBs to less than 1 PPM at low temperatures and pressures. SET{sup TM} is a proven, safe and cost-effective alternative to incineration for some of the most difficult waste treatment problems that exist today. (authors)

Foutz, W.L.; Rogers, J.E.; Mather, J.D. [Commodore Advanced Sciences, Inc., Richland, WA (United States)

2008-07-01T23:59:59.000Z

186

Probing adsorbate dynamics with chirped laser pulses in a single-pulse scheme F. Steeb,1 S. Mathias,1 M. Wiesenmayer,2 A. Fischer,1 M. Aeschlimann,1 M. Bauer,2,*, and J. P. Gauyacq3,4,*,  

E-Print Network (OSTI)

Probing adsorbate dynamics with chirped laser pulses in a single-pulse scheme F. Steeb,1 S. Mathias of the adsorbate mo- tion. The results enable us to assign characteristic chirped-pulse 2PPE features to the ultrafast adsorbate dynamics associated with the excited state lifetime and the adsorbate motion

Aeschlimann, Martin

187

Protein folding mediated by solvation: water expelling and formation of the hydrophobic core occurs after the structure collapse  

E-Print Network (OSTI)

The interplay between structure-search of the native structure and desolvation in protein folding has been explored using a minimalist model. These results support a folding mechanism where most of the structural formation of the protein is achieved before water is expelled from the hydrophobic core. This view integrates water expulsion effects into the funnel energy landscape theory of protein folding. Comparisons to experimental results are shown for the SH3 protein. After the folding transition, a near-native intermediate with partially solvated hydrophobic core is found. This transition is followed by a final step that cooperatively squeezes out water molecules from the partially hydrated protein core.

Margaret S. Cheung; Angel E. Garcia; Jose N. Onuchic

2002-03-31T23:59:59.000Z

188

Dynamic optical properties in graphene: Length versus velocity gauge  

SciTech Connect

The dynamic optical properties of graphene are theoretically investigated in both length gauge and velocity gauge in the presence of ultrafast optical radiation field. The two gauges present different results of dynamic photo-induced carriers and optical conductance due to distinct dependencies on electric field and non-resonant optical absorption, while the two gauges give identical results in the steady state time. It shows that the choice of gauge affects evidently the dynamic optical properties of graphene. The velocity gauge represents an outcome of a real physical experiment.

Dong, H. M.; Han, K., E-mail: han6409@263.net [Department of Physics, China University of Mining and Technology, Xuzhou 221116 (China); Xu, W. [Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei 230031 (China); Department of Physics, Yunnan University, Kunming 650091 (China)

2014-02-14T23:59:59.000Z

189

Ion distribution around a charged rod in one and two component solvents: Preferential solvation and first order ionization phase transition  

E-Print Network (OSTI)

In one and two component solvents, we calculate the counterion distribution around a charged rod treating the degree of ionization $\\alpha$ as an annealed variable dependent on its local environment. In the one component case, $\\alpha$ is determined under various conditions without and with salt. In the two component case, we take into account the preferential solvation of the counterions and the ionized monomers and the short-range interaction between the rod and the solvent without salt. It then follows a composition-dependent mass action law. Mesoscopic variations of the composition and the counterions are produced around a chraged rod, which sensitively depend on various parameters of the molecular interactions. Furthermore, we predict a first order phase transition of weak-to-strong dissociation for strong preferential solvation. It can occur in expanded states of a polymer chain. This transition line starts from a point on the solvent coexistence curve and ends at a critical point in the plane of the temperature and the solvent composition. The composition change around a charged rod is long-ranged near the solvent critical point.

Ryuichi Okamoto; Akira Onuki

2009-05-10T23:59:59.000Z

190

Double Wall Carbon Nanotubes for Wide-Band, Ultrafast Pulse Generation  

E-Print Network (OSTI)

mode-locking. The concentric tube arrangement makes DWNTs an interesting class of nanomaterials, with a wide-ranging potential applications, including in (opto)electronics.52-54 Of particular interest relevant to this work, DWNTs also exhibit ultrafast... .; Ferrari, A. C., in Molecular- and Nano-Tubes, (Eds: Hayden, O., Nielsch, K.), Springer US, 2011. [43] Bonaccorso, F.; Sun, Z.; Hasan, T.; Ferrari, A. C. Graphene Photonics and Optoelectronics. Nat. Photon. 2010, 4, 611-622. [44] Boyd, R. W., Nonlinear...

Hasan, Tawfique; Sun, Zhipei; Tan, PingHeng; Popa, Daniel; Flahaut, Emmanuel; Kelleher, Edmund J. R.; Bonaccorso, Francesco; Wang, Fengqiu; Jiang, Zhe; Torrisi, Felice; Privitera, Giulia; Nicolosi, Valeria; Ferrari, Andrea C.

2014-04-15T23:59:59.000Z

191

Solvation Structures and Dynamics of the Magnesium Chloride (Mg2+–Cl–) Ion Pair in Water–Ethanol Mixtures  

Science Journals Connector (OSTI)

E-mail: A.C., anupam.chatterjee@chem.iitb.ac.in; M.K.D., mayankd@chem.iitb.ac.in. ... Jorgensen, W. L.; Chandrasekhar, J.; Madura, J. D.; Impey, R. W.; Klein, M. L.Comparison of Simple Potential Functions for Simulating Liquid Water J. Chem. ...

Anupam Chatterjee; Mayank Kumar Dixit; B. L. Tembe

2013-07-05T23:59:59.000Z

192

Non-Aqueous Solvation of n-Octanol and Ethanol: Spectroscopic and Computational Lori M. Levering, Carrigan J. Hayes, Karen M. Callahan, Christopher M. Hadad,* and  

E-Print Network (OSTI)

Non-Aqueous Solvation of n-Octanol and Ethanol: Spectroscopic and Computational Studies Lori M-H bonds in n-octanol and ethanol with the organic solvents carbon tetrachloride (CCl4), cyclohexane populations of each ethanol complex and are consistent with the experimental results. Additional spectra were

193

Cisplatin Binding to DNA Oligomers from Hybrid Car-Parrinello/Molecular Dynamics Simulations  

Science Journals Connector (OSTI)

The first-principles calculations are carried out with the Car-Parrinello approach,52 which has proven to reliably describe structure, dynamics, and electronic properties of platinum?nucleotide complexes in the solid state53 as well as in water solution. ... There are more than three waters in the first solvation shell of AM1. ... The predictive power of our computational setup was investigated by constructing a structural model of platinated DNA. ...

Katrin Spiegel; Ursula Rothlisberger; Paolo Carloni

2004-01-29T23:59:59.000Z

194

Particle beam dynamics | Princeton Plasma Physics Lab  

NLE Websites -- All DOE Office Websites (Extended Search)

Particle beam dynamics Particle beam dynamics Subscribe to RSS - Particle beam dynamics The study of the physics of charged particle beams and the accelerators that produce them. This cross-disciplinary area intersects with fields such as plasma physics, high-energy density science, and ultra-fast lasers. Premiere issue of "Quest" magazine details PPPL's strides toward fusion energy and advances in plasma science Quest Magazine Summer 2013 Welcome to the premiere issue of Quest, the annual magazine of the U.S. Department of Energy's Princeton Plasma Physics Laboratory (PPPL). Read more about Premiere issue of "Quest" magazine details PPPL's strides toward fusion energy and advances in plasma science Ronald C Davidson Ronald Davidson heads PPPL research on charged particle beam dynamics and

195

Synchrotron ultrafast techniques for photoactive transition metal complexes  

Science Journals Connector (OSTI)

...structural dynamics including solvent rearrangements. The price to pay to have access to such unique information is loss in...and A Zecchina. 2005 The structure of active centers and the ethylene polymerization mechanism on the Cr/SiO2 catalyst: a frontier...

2013-01-01T23:59:59.000Z

196

A Near-Infrared Transient Absorption Study of the Excited-State Dynamics of the Carotenoid Spirilloxanthin in Solution and in the LH1 Complex of Rhodospirillum rubrum  

E-Print Network (OSTI)

A Near-Infrared Transient Absorption Study of the Excited-State Dynamics of the Carotenoid rubrum were studied by near-infrared ultrafast transient absorption spectroscopy. Global analysis), does not exhibit detectable spectral features in the near-infrared region. Introduction The excited

van Stokkum, Ivo

197

Synthesis, Characterization, and Ultrafast Dynamics of Metal, Metal Oxide, and Semiconductor Nanomaterials  

E-Print Network (OSTI)

electron storage, electrochromic, and photoelectrochromicV. Thin Solid Films Electrochromic and photoelectrochemical

Wheeler, Damon Andreas

2013-01-01T23:59:59.000Z

198

Ultrafast Electron Transfer Dynamics in Ruthenium Polypyridyl Complexes with a -Conjugated Ligand  

E-Print Network (OSTI)

to the solvent and orders of magnitude more rapidly than in previously studied ruthenium-diquat or ruthenium [(bpy)2RuLDQ]4+ (Chart 1) by broadband femtosecond transient absorption spectroscopy in acetonitrile

Dutta, Prabir K.

199

Synthesis, Characterization, and Ultrafast Dynamics of Metal, Metal Oxide, and Semiconductor Nanomaterials  

E-Print Network (OSTI)

cancer treatment, sensors, lasers, and solar cells. Onedetectors, solar energy conversion, sensors, and manydetectors, solar energy conversion, lasers, and sensors. A

Wheeler, Damon Andreas

2013-01-01T23:59:59.000Z

200

Synthesis, Characterization, and Ultrafast Dynamics of Metal, Metal Oxide, and Semiconductor Nanomaterials  

E-Print Network (OSTI)

S. R. ; Cowan, A. J. ; Barroso, M. ; Sivula, K. ; Ye, J. ;3861. (167) Pendlebury, S. R. ; Barroso, M. ; Cowan, A. J. ;+. (199) Pendlebury, S. ; Barroso, M. ; Cowan, A. ; Sivula,

Wheeler, Damon Andreas

2013-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "ultrafast solvation dynamics" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


201

Circularly Polarized X Rays: Another Probe of Ultrafast Molecular Decay Dynamics  

SciTech Connect

Dissociative nuclear motion in core-excited molecular states leads to a splitting of the fragment Auger lines: the Auger-Doppler effect. We present here for the first time experimental evidence for an Auger-Doppler effect following F1s{yields}a{sub 1g}* inner-shell excitation by circularly polarized x rays in SF{sub 6}. In spite of a uniform distribution of the dissociating S-F bonds near the polarization plane of the light, the intersection between the subpopulation of molecules selected by the core excitation with the cone of dissociation induces a strong anisotropy in the distribution of the S-F bonds that contributes to the scattering profile measured in the polarization plane.

Travnikova, Oksana; Lindblad, Andreas; Nicolas, Christophe; Soederstroem, Johan; Kimberg, Victor; Miron, Catalin [Synchrotron SOLEIL, L'Orme des Merisiers, Saint-Aubin, B.P. 48, F-91192 Gif-sur-Yvette Cedex (France); Liu Jicai; Gel'mukhanov, Faris [Department of Theoretical Chemistry, Roslagstullsbacken 15, Royal Institute of Technology, S-106 91 Stockholm (Sweden)

2010-12-03T23:59:59.000Z

202

Ultrafast Energy Flow and Equilibration Dynamics in Photosynthetic Light-Harvesting Complexes  

Science Journals Connector (OSTI)

We disentangle various energy transfer pathways in the bacterio-chlorophyll excitation cascade from LH2 to LH1 in Chromatium vinosum grown under high-light or low-light illumination...

Maiuri, Margherita; Luer, Larry; Henry, Sarah; Carey, Anne-Marie; Cogdell, Richard; Cerullo, Giulio; Polli, Dario

203

Ultrafast Magnetization Dynamics of SrRuO3 Thin Films  

SciTech Connect

Itinerant ferromagnet SrRuO3 has drawn interest from physicists due to its unusual transport and magnetic properties as well as from engineers due to its low resistivity and good lattice-matching to other oxide materials. The exact electronic structure remains a mystery, as well as details of the interactions between magnetic and electron transport properties. This thesis describes the use of time-resolved magneto-optical Kerr spectroscopy to study the ferromagnetic resonance of SrRuO3 thin films, where the ferromagnetic resonance is initiated by a sudden change in the easy axis direction in response to a pump pulse. The rotation of the easy axis is induced by laser heating, taking advantage of a temperature-dependent easy axis direction in SrRuO3 thin films. By measuring the change in temperature of the magnetic system in response to the laser pulse, we find that the specific heat is dominated by magnons up to unusually high temperature, ~;;100 K, and thermal diffusion is limited by a boundary resistance between the film and the substrate that is not consistent with standard phonon reflection and scattering models. We observe a high FMR frequency, 250 GHz, and large Gilbert damping parameter, alpha ~;; 1, consistent with strong spin-orbit coupling. We observe a time-dependent change in the easy axis direction on a ps time-scale, and we find that parameters associated with the change in easy axis, as well as the damping parameter, have a non-monotonic temperature dependence similar to that observed in anomalous Hall measurements.

Langner, Matthew C

2009-05-19T23:59:59.000Z

204

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)

'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.

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

2011-11-02T23:59:59.000Z

205

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)  

SciTech Connect

'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.

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

2011-05-01T23:59:59.000Z

206

Microsoft PowerPoint - WishartUltrafastAccelFinal.ppt [Read-Only]  

NLE Websites -- All DOE Office Websites (Extended Search)

June 25-28, 2004 Chemistry Department Brookhaven National Laboratory LEAF LEAF Office of Basic Energy Sciences U.S. Department of Energy Advanced Energy Systems 2 Tabata Meeting and Satellite Symposia March 10 and 11, 2000 "New Applications and Facilities of Radiation on Radiation Chemistry, Material Science, And Radiation Biology for Future Radiation Science and Technology" Osaka University Institute of Scientific and Industrial Research, Osaka March 13 - 17, 2000 "International Symposium on Prospects for Application of Radiation Towards the 21st Century" Waseda University, Tokyo March 20, 2000 "Development of Ultrafast Detection Systems for Radiation Chemistry" Univ. of Tokyo Nuclear Engineering Research Laboratory in Tokai-Mura The Brookhaven LEAF

207

Measurements of Ionic Structure in Shock Compressed Lithium Hydride from Ultrafast X-Ray Thomson Scattering  

SciTech Connect

We present the first ultrafast temporally, spectrally, and angularly resolved x-ray scattering measurements from shock-compressed matter. The experimental spectra yield the absolute elastic and inelastic scattering intensities from the measured density of free electrons. Laser-compressed lithium-hydride samples are well characterized by inelastic Compton and plasmon scattering of a K-alpha x-ray probe providing independent measurements of temperature and density. The data show excellent agreement with the total intensity and structure when using the two-species form factor and accounting for the screening of ion-ion interactions.

Kritcher, A. L. [L-399, Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94551 (United States); Department of Nuclear Engineering, University of California Berkeley, Berkeley, California 94709 (United States); Neumayer, P.; Doeppner, T.; Landen, O. L.; Glenzer, S. H. [L-399, Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94551 (United States); Brown, C. R. D. [Department of Physics, Imperial College, London SW7 2AZ (United Kingdom); AWE plc., Aldermaston, Reading, RG7 4PR (United Kingdom); Davis, P. [L-399, Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94551 (United States); Department of Physics, University of California Berkeley, Berkeley, California 94709 (United States); Falcone, R. W.; Lee, H. J. [Department of Physics, University of California Berkeley, Berkeley, California 94709 (United States); Gericke, D. O.; Vorberger, J.; Wuensch, K. [CFSA, Department of Physics, University of Warwick, Coventry CV4 7AL (United Kingdom); Gregori, G. [Department of Physics, Oxford University, Oxford OX1 3PU (United Kingdom); Holst, B.; Redmer, R. [Universitaet Rostock, Institut fuer Physik, D-18051 Rostock (Germany); Morse, E. C. [Department of Nuclear Engineering, University of California Berkeley, Berkeley, California 94709 (United States); Pelka, A.; Roth, M. [Institut fuer Kernphysik, Technische Universitaet Darmstadt, Darmstadt (Germany)

2009-12-11T23:59:59.000Z

208

Polymer–Graphene Nanocomposites as Ultrafast-Charge and -Discharge Cathodes for Rechargeable Lithium Batteries  

SciTech Connect

Electroactive polymers are a new generation of 'green' cathode materials for rechargeable lithium batteries. We have developed nanocomposites combining graphene with two promising polymer cathode materials, poly(anthraquinonyl sulfide) and polyimide, to improve their high-rate performance. The polymer-graphene nanocomposites were synthesized through a simple in-situ polymerization in the presence of graphene sheets. The highly dispersed graphene sheets in the nanocomposite drastically enhanced the electronic conductivity and allowed the electrochemical activity of the polymer cathode to be efficiently utilized. This allows for ultrafast charging and discharging - the composite can deliver more than 100 mAh/g within just a few seconds.

Song, Zhiping; Xu, Terrence (Tianren) [Tianren; Gordin, Mikhail; Jiang, Yingbing; Bae, In-Tae; Xiao, Qiangfeng; Zhan, Hui; Liu, Jun; Wang, Donghai

2012-05-09T23:59:59.000Z

209

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

SciTech Connect

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.

Ristow, Oliver; Merklein, Moritz; Grossmann, Martin; Hettich, Mike; Schubert, Martin; Bruchhausen, Axel; Scheer, Elke; Dekorsy, Thomas; Barretto, Elaine C. S., E-mail: elaine.barretto@uni-konstanz.de [Department of Physics and Center of Applied Photonics, University of Konstanz, D-78457 Konstanz (Germany)] [Department of Physics and Center of Applied Photonics, University of Konstanz, D-78457 Konstanz (Germany); Grebing, Jochen; Erbe, Artur [Helmholtz-Zentrum Dresden - Rossendorf, Institute of Ion-Beam Physics and Materials Research, D-01328 Dresden (Germany)] [Helmholtz-Zentrum Dresden - Rossendorf, Institute of Ion-Beam Physics and Materials Research, D-01328 Dresden (Germany); Mounier, Denis [IMMM, UMR-CNRS 6283, ENSIM, PRES UNAM, Université du Maine, 72085 Le Mans (France)] [IMMM, UMR-CNRS 6283, ENSIM, PRES UNAM, Université du Maine, 72085 Le Mans (France); Gusev, Vitalyi [LAUM, UMR-CNRS 6613, PRES UNAM, Université du Maine, 72085 Le Mans (France)] [LAUM, UMR-CNRS 6613, PRES UNAM, Université du Maine, 72085 Le Mans (France)

2013-12-02T23:59:59.000Z

210

Temperature dependent photoexcited carrier dynamics in multiferroic BiFeO{sub 3} film: A hidden phase transition  

SciTech Connect

The ultrafast carrier dynamics of the multiferroic BiFeO{sub 3} film in a broad temperature range is investigated using optical pump-probe spectroscopy. The photoexcited electrons release their energy with optical phonons emission through electron-phonon coupling in about 1 ps. The following intermediate process is identified as dynamical spin-lattice coupling in several picoseconds. Furthermore, the peak values of the optical reflectivity and the time constants of carrier relaxation channels show significant changes while the temperature varies from 137.5?K to around 195?K, this aligns with the previously reported hidden phase transition. Our study demonstrates that ultrafast spectroscopy is a sensitive method to look into the dynamical interactions among the on-site high-energy electrons accumulated in the p conduction band of Bi, coherent optical phonon, as well as the spin degree of freedom. These features play crucial roles in the characterization of phase transitions.

Zhang, Zeyu; Jin, Zuanming; Pan, Qunfeng; Xu, Yue; Lin, Xian; Ma, Guohong, E-mail: ghma@staff.shu.edu.cn, E-mail: cheng@uow.edu.au [Department of Physics, Shanghai University, Shanghai 200444 (China); Cheng, Zhenxiang, E-mail: ghma@staff.shu.edu.cn, E-mail: cheng@uow.edu.au [Department of Physics, Shanghai University, Shanghai 200444 (China); Institute for Superconducting and Electronic Materials, University of Wollongong, New South Wales 2500 (Australia)

2014-04-14T23:59:59.000Z

211

Ultrafast laser based coherent control methods for explosives detection  

SciTech Connect

The detection of explosives is a notoriously difficult problem, especially at stand-off, due to their (generally) low vapor pressure, environmental and matrix interferences, and packaging. We are exploring Optimal Dynamic Detection of Explosives (ODD-Ex), which exploits the best capabilities of recent advances in laser technology and recent discoveries in optimal shaping of laser pulses for control of molecular processes to significantly enhance the standoff detection of explosives. The core of the ODD-Ex technique is the introduction of optimally shaped laser pulses to simultaneously enhance sensitivity to explosives signatures while dramatically improving specificity, particularly against matrix materials and background interferences. These goals are being addressed by operating in an optimal non-linear fashion, typically with a single shaped laser pulse inherently containing within it coherently locked control and probe subpulses. Recent results will be presented.

Moore, David Steven [Los Alamos National Laboratory

2010-12-06T23:59:59.000Z

212

Vibrational Spectra of Water Solutions of Azoles from QM/MM Calculations: Effects of Solvation  

E-Print Network (OSTI)

, pyridinic nitrogen. Such hydration sites give high solubility to these compounds in water molecular dynamics (MD) study.1 Gas phase quantum mechanics methods indicated that water molecules may be sensitive to the solvent. Several experimental Raman and IR studies were reported for gas phase2 water

Guidoni, Leonardo

213

Ultrafast Spectroscopic Study on Caffeine Mediated Dissociation of Mutagenic Ethidium from Synthetic DNA and Various Cell Nuclei  

Science Journals Connector (OSTI)

Ultrafast Spectroscopic Study on Caffeine Mediated Dissociation of Mutagenic Ethidium from Synthetic DNA and Various Cell Nuclei ... (10) The purified (reverse-phase cartridge) synthetic DNA oligonucleotides of 12 bases (dodecamer) with sequence CGCGAATTCGCG were obtained from TriLink. ... In Figure 1a,b steady-state and time-resolved studies on the Et intercalated to the synthetic DNA are presented. ...

Soma Banerjee; Debajit Bhowmik; Pramod Kumar Verma; Rajib Kumar Mitra; Anirban Sidhhanta; Gautam Basu; Samir Kumar Pal

2011-10-27T23:59:59.000Z

214

Free electron properties of metals under ultrafast laser-induced electron-phonon nonequilibrium: a first-principles study  

E-Print Network (OSTI)

Free electron properties of metals under ultrafast laser-induced electron-phonon nonequilibrium CEA-DIF, 91297 Arpajon, France (Dated: April 3, 2014) The electronic behavior of various solid metals modelled based on the free electron classical theory, the free electron number is a key parameter. However

Paris-Sud XI, Université de

215

Ultrafast Microfluidic Mixer and Freeze-Quenching Yu Lin, Gary J. Gerfen, Denis L. Rousseau, and Syun-Ru Yeh*  

E-Print Network (OSTI)

Ultrafast Microfluidic Mixer and Freeze-Quenching Device Yu Lin, Gary J. Gerfen, Denis L. Rousseau fluids. To overcome these problems, we have designed and tested a novel microfluidic silicon mixer. The mixed-solution jet, with a cross section of 10 µm � 100 µm, exits from the microfluidic silicon mixer

Yeh, Syun-Ru

216

Hydrogen Bond Switching among Flavin and Amino Acid Side Chains in the BLUF Photoreceptor Observed by Ultrafast Infrared Spectroscopy  

E-Print Network (OSTI)

Hydrogen Bond Switching among Flavin and Amino Acid Side Chains in the BLUF Photoreceptor Observed hydrogen-bond network with nearby amino acid side chains, including a highly conserved tyrosine and glutamine. The participation of particular amino acid side chains in the ultrafast hydrogen-bond switching

van Stokkum, Ivo

217

Princeton Plasma Physics Lab - Particle beam dynamics  

NLE Websites -- All DOE Office Websites (Extended Search)

particle-beam-dynamics The study of particle-beam-dynamics The study of the physics of charged particle beams and the accelerators that produce them. This cross-disciplinary area intersects with fields such as plasma physics, high-energy density science, and ultra-fast lasers. en Premiere issue of "Quest" magazine details PPPL's strides toward fusion energy and advances in plasma science http://www.pppl.gov/news/2013/09/premiere-issue-quest-magazine-details-pppls-strides-toward-fusion-energy-and-advances-0

218

Precision lifetime measurements of a single trapped ion with ultrafast laser pulses  

SciTech Connect

We report precision measurements of the excited state lifetime of the 5p {sup 2}P{sub 1/2} and 5p {sup 2}P{sub 3/2} levels of a single trapped Cd{sup +} ion. Combining ion trap and ultrafast laser technologies, the ion is excited with picosecond laser pulses from a mode-locked laser and the distribution of arrival times of spontaneously emitted photons is recorded. The resulting lifetimes are 3.148{+-}0.011 ns and 2.647{+-}0.010 ns for {sup 2}P{sub 1/2} and {sup 2}P{sub 3/2} respectively. With a total uncertainty of under 0.4%, these are among the most precise measurements of any atomic state lifetimes to date.

Moehring, D. L.; Blinov, B. B.; Gidley, D. W.; Kohn, R. N. Jr.; Madsen, M. J.; Sanderson, T. D.; Vallery, R. S.; Monroe, C. [FOCUS Center and Department of Physics, University of Michigan, Ann Arbor, Michigan 48109-1040 (United States)

2006-02-15T23:59:59.000Z

219

Ultrafast Spin Avalanches in Crystals of Nanomagnets in Terms of Magnetic Detonation  

Science Journals Connector (OSTI)

Recent experiments [W. Decelle et al., Phys. Rev. Lett. 102, 027203 (2009)] have discovered ultrafast propagation of spin avalanches in crystals of nanomagnets, which is 3 orders of magnitude faster than the traditionally studied magnetic deflagration. The new regime has been hypothetically identified as magnetic detonation. Here we demonstrate unequivocally the possibility of magnetic detonation in the crystals, as a front consisting of a leading shock and a zone of Zeeman energy release. We study the key features of the process and find that the magnetic detonation speed only slightly exceeds the sound speed in agreement with the experimental observations. For combustion science, our results provide a unique physical example of extremely weak detonation.

M. Modestov; V. Bychkov; M. Marklund

2011-11-11T23:59:59.000Z

220

Ultrafast electronic read-out of diamond NV centers coupled to graphene  

E-Print Network (OSTI)

Nonradiative transfer processes are often regarded as loss channels for an optical emitter1, since they are inherently difficult to be experimentally accessed. Recently, it has been shown that emitters, such as fluorophores and nitrogen vacancy centers in diamond, can exhibit a strong nonradiative energy transfer to graphene. So far, the energy of the transferred electronic excitations has been considered to be lost within the electron bath of the graphene. Here, we demonstrate that the trans-ferred excitations can be read-out by detecting corresponding currents with picosecond time resolution. We electrically detect the spin of nitrogen vacancy centers in diamond electronically and con-trol the nonradiative transfer to graphene by electron spin resonance. Our results open the avenue for incorporating nitrogen vacancy centers as spin qubits into ultrafast electronic circuits and for harvesting non-radiative transfer processes electronically.

Brenneis, Andreas; Seifert, Max; Karl, Helmut; Brandt, Martin S; Huebl, Hans; Garrido, Jose A; Koppens, Frank H L; Holleitner, Alexander W

2014-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "ultrafast solvation dynamics" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


221

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

SciTech Connect

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.

Itoh, Hirotake, E-mail: hiroitoh@m.tohoku.ac.jp; Iwai, Shinichiro, E-mail: s-iwai@m.tohoku.ac.jp [Department of Physics, Tohoku University, Sendai 980-8578 (Japan); JST, CREST, Sendai 980-8578 (Japan); Itoh, Keisuke; Goto, Kazuki [Department of Physics, Tohoku University, Sendai 980-8578 (Japan); Yamamoto, Kaoru [Department of Applied Physics, Okayama University of Science, Okayama 700-0005 (Japan); Yakushi, Kyuya [Toyota Physical and Chemical Research Institute, Nagakute 480-1192 (Japan)

2014-04-28T23:59:59.000Z

222

Phonon-Assisted Ultrafast Charge Separation in a Realistic PCBM Aggregate  

E-Print Network (OSTI)

Organic solar cells must separate strongly bound electron-hole pairs into free charges. This is achieved at interfaces between electron donor and acceptor organic semiconductors. The most popular electron acceptor is the fullerene derivative PCBM. Electron-hole separation has been observed on femtosecond timescales, which is incompatible with conventional Marcus theories of organic transport. In this work we show that ultrafast charge transport in PCBM arises from its broad range of electronic eigenstates, provided by the presence of three closely spaced delocalised bands near the LUMO level. Vibrational fluctuations enable rapid transitions between these bands, which drives an electron transport of $\\sim$3 nm within 100 fs. All this is demonstrated within a realistic tight binding Hamiltonian containing transfer integrals no larger than 8 meV.

Samuel L. Smith; Alex W. Chin

2014-06-25T23:59:59.000Z

223

Evidence for ultra-fast heating in intense-laser irradiated reduced-mass targets  

SciTech Connect

We report on an experiment irradiating individual argon droplets of 20 {mu}m diameter with laser pulses of several Joule energy at intensities of 10{sup 19} W/cm{sup 2}. K-shell emission spectroscopy was employed to determine the hot electron energy fraction and the time-integrated charge-state distribution. Spectral fitting indicates that bulk temperatures up to 160 eV are reached. Modelling of the hot-electron relaxation and generation of K-shell emission with collisional hot-electron stopping only is incompatible with the experimental results, and the data suggest an additional ultra-fast (sub-ps) heating contribution. For example, including resistive heating in the modelling yields a much better agreement with the observed final bulk temperature and qualitatively reproduces the observed charge state distribution.

Neumayer, P.; Gumberidze, A.; Hochhaus, D. C. [ExtreMe Matter Institute EMMI and Research Division, GSI Helmholtzzentrum fuer Schwerionenforschung, 64291 Darmstadt (Germany); Frankfurt Institute for Advanced Studies FIAS, 60438 Frankfurt am Main (Germany); Aurand, B.; Stoehlker, T. [Helmholtzzentrum fuer Schwerionenforschung GSI, 64291 Darmstadt (Germany); Helmholtz Institute Jena, 07743 Jena (Germany); Costa Fraga, R. A.; Kalinin, A. [Institut fuer Kernphysik, J. W. Goethe University Frankfurt, 60438 Frankfurt am Main (Germany); Ecker, B. [Johannes Gutenberg University Mainz, 55099 Mainz (Germany); Helmholtz Institute Jena, 07743 Jena (Germany); Grisenti, R. E. [Institut fuer Kernphysik, J. W. Goethe University Frankfurt, 60438 Frankfurt am Main (Germany); Helmholtzzentrum fuer Schwerionenforschung GSI, 64291 Darmstadt (Germany); Kaluza, M. C. [Helmholtz Institute Jena, 07743 Jena (Germany); IOQ Institute of Optics and Quantum Electronics, University of Jena (Germany); Kuehl, T. [Johannes Gutenberg University Mainz, 55099 Mainz (Germany); Helmholtzzentrum fuer Schwerionenforschung GSI, 64291 Darmstadt (Germany); Helmholtz Institute Jena, 07743 Jena (Germany); Polz, J. [IOQ Institute of Optics and Quantum Electronics, University of Jena (Germany); Reuschl, R. [ExtreMe Matter Institute EMMI and Research Division, GSI Helmholtzzentrum fuer Schwerionenforschung, 64291 Darmstadt (Germany); Winters, D.; Winters, N.; Yin, Z. [Helmholtzzentrum fuer Schwerionenforschung GSI, 64291 Darmstadt (Germany)

2012-12-15T23:59:59.000Z

224

Hydrogen-Bonding Structure and Dynamics of Aqueous Carbonate Species from Car?Parrinello Molecular Dynamics Simulations  

Science Journals Connector (OSTI)

A comprehensive Car?Parrinello molecular dynamics (CP-MD) study of aqueous solutions of carbonic acid (H2CO3), bicarbonate (HCO3?), carbonate (CO32?), and carbon dioxide (CO2) provides new quantitative insight into the structural and dynamic aspects of the hydrogen-bonding environments for these important aqueous species and their effects on the structure, H-bonding, and dynamical behavior of the surrounding water molecules. ... The power spectra of the carbonate species were calculated as Fourier transforms of their velocity autocorrelation functions over the 14 ps production trajectories of the CP-MD simulations. ... The first solvation shell of the anion was found to contain between five and six hydrogen bonded water mols., compared to the six to seven waters found in analogous classical studies based on empirical potentials. ...

P. Padma Kumar; Andrey G. Kalinichev; R. James Kirkpatrick

2008-12-24T23:59:59.000Z

225

Frequency modulated few-cycle optical pulse trains induced controllable ultrafast coherent population oscillations in three-level atomic systems  

E-Print Network (OSTI)

We report a study on the ultrafast coherent population oscillations (UCPO) in two level atoms induced by the frequency modulated few-cycle optical pulse train. The phenomenon of UCPO is investigated by numerically solving the optical Bloch equations beyond the rotating wave approximation. We demonstrate that the quantum state of the atoms and the frequency of UCPO may be controlled by controlling the number of pulses in the pulse trains and the pulse repetition time respectively. Moreover, the robustness of the population inversion against the variation of the laser pulse parameters is also investigated. The proposed scheme may be useful for the creation of atoms in selected quantum state for desired time duration and may have potential applications in ultrafast optical switching.

Parvendra Kumar; Amarendra K. Sarma

2012-11-16T23:59:59.000Z

226

Chirped-pulse manipulated carrier dynamics in low-temperature molecular-beam-epitaxy grown GaAs  

SciTech Connect

Chirped pulse controlled carrier dynamics in low-temperature molecular-beam-epitaxy grown GaAs are investigated by degenerate pump-probe technique. Varying the chirped condition of excited pulse from negative to positive increases the carrier relaxation time so as to modify the dispersion and reshape current pulse in time domain. The spectral dependence of carrier dynamics is analytically derived and explained by Shockley-Read Hall model. This observation enables the new feasibility of controlling carrier dynamics in ultrafast optical devices via the chirped pulse excitations.

Lee, Chao-Kuei, E-mail: chuckcklee@yahoo.com [Department of Photonics, National Sun-Yat-Sen University, Kaohsiung 80400, Taiwan (China); Lin, Yuan-Yao [Department of Electrical Engineering, Institute of Photonics Technologies, National Tsing Hua University, Hsinchu 30010, Taiwan (China); Lin, Sung-Hui [Department of Photonics, National Chiao Tung University, Hsinchu 30010, Taiwan (China); Lin, Gong-Ru [Department of Electrical Engineering, Graduate Institute of Photonics and Optoelectronics, National Taiwan University, No. 1, Roosevelt Road, Sec. 4, Taipei 10617, Taiwan (China); Pan, Ci-Ling [Department of Photonics, National Chiao Tung University, Hsinchu 30010, Taiwan (China); Department of Physics, National Tsing Hwa University, Hsinchu 30010, Taiwan (China)

2014-04-28T23:59:59.000Z

227

Change of caged dynamics at Tg in hydrated proteins found after suppressing the methyl-group rotation contribution  

E-Print Network (OSTI)

In conventional glassformers at sufficiently short times and low enough temperatures, molecules are mutually caged by the intermolecular potential. The fluctuation and dissipation from motion of caged molecules when observed by elastic incoherent neutron scattering exhibit a change in temperature dependence of the mean square displacement (MSD) at the glass transition temperature Tg. This is a general and fundamental property of caged dynamics in glassformers, which is observed always near Tg independent of the energy resolution of the spectrometer. Recently we showed the same change of T-dependence at Tg is present in proteins solvated with bioprotectants, coexisting with the dynamic transition at a higher temperature Td. In these solvated proteins, all having Tg and Td higher than the proteins hydrated by water alone, the observation of the change of T-dependence of the MSD at Tg is unobstructed by the methyl-group rotation contribution at lower temperatures. On the other hand, proteins hydrated by water alone have lower Tg and Td, and hence unambiguous evidence of the transition of MSD at Tg is hard to find. Notwithstanding, evidence on the break of the MSD at Tg can be found by deuterating the protein to suppress the methyl-group contribution. An alternative strategy is the use of a spectrometer that senses motions faster than 15 ps, which confers the benefit of shifting both the onset of methyl-group rotation contribution as well as the dynamic transition to higher temperatures, and again the change of MSD at Tg becomes evident. The break of the elastic intensity or the MSD at Tg coexists with the dynamics transition at Td in hydrated and solvated proteins. Recognition of this fact helps to remove inconsistency and conundrum encountered in interpreting the data that thwart progress in understanding the origin of the dynamic transition and its connection to biological function.

K. L. Ngai; S. Capaccioli; A. Paciaroni

2011-06-29T23:59:59.000Z

228

Hydration dynamics near a model protein surface  

E-Print Network (OSTI)

AE, Onuchic JN. 2002. Protein folding mediated by solvation:of hydration forces in protein folding. Journal of Physicalthe broader context of protein folding and function and as

Russo, Daniela; Hura, Greg; Head-Gordon, Teresa

2003-01-01T23:59:59.000Z

229

Optoacoustic Microscopy for Investigation of Material Nanostructures-Embracing the Ultrasmall, Ultrafast, and the Invisible  

SciTech Connect

The goal of this grant was the development of a new type of scanning acoustic microscope for nanometer resolution ultrasound imaging, based on ultrafast optoacoustics (>GHz). In the microscope, subpicosecond laser pulses was used to generate and detect very high frequency ultrasound with nanometer wavelengths. We report here on the outcome of the 3-year DOE/BES grant which involved the design, multifaceted construction, and proof-of-concept demonstration of an instrument that can be used for quantitative imaging of nanoscale material features – including features that may be buried so as to be inaccessible to conventional lightwave or electron microscopies. The research program has produced a prototype scanning optoacoustic microscope which, in combination with advanced computational modeling, is a system-level new technology (two patents issues) which offer novel means for precision metrology of material nanostructures, particularly those that are of contemporary interest to the frontline micro- and optoelectronics device industry. For accomplishing the ambitious technical goals, the research roadmap was designed and implemented in two phases. In Phase I, we constructed a “non-focusing” optoacoustic microscope instrument (“POAM”), with nanometer vertical (z-) resolution, while limited to approximately 10 micrometer scale lateral recolution. The Phase I version of the instrument which was guided by extensive acoustic and optical numerical modeling of the basic underlying acoustic and optical physics, featured nanometer scale close loop positioning between the optoacoustic transducer element and a nanostructured material sample under investigation. In phase II, we implemented and demonstrated a scanning version of the instrument (“SOAM”) where incident acoustic energy is focused, and scanned on lateral (x-y) spatial scale in the 100 nm range as per the goals of the project. In so doing we developed advanced numerical simulations to provide computational models of the focusing of multi-GHz acoustic waves to the nanometer scale and innovated a series fabrication approaches for a new type of broadband high-frequency acoustic focusing microscope objective by applying methods on nanoimprinting and focused-ion beam techniques. In the following, the Phase I and Phase II instrument development is reported as Section II. The first segment of this section describes the POAM instrument and its development, while including much of the underlying ultrafast acoustic physics which is common to all of our work for this grant. Then, the science and engineering of the SOAM instrument is described, including the methods of fabricating new types of acoustic microlenses. The results section is followed by reports on publications (Section III), Participants (Section IV), and statement of full use of the allocated grant funds (Section V).

Nurmikko, Arto; Humphrey, Maris

2014-07-10T23:59:59.000Z

230

Ultrafast ignition with relativistic shock waves induced by high power lasers  

E-Print Network (OSTI)

In this paper we consider laser intensities larger than $10^{16} W/cm^2$ where the ablation pressure is negligible in comparison with the radiation pressure. The radiation pressure is caused by the ponderomotive force acting mainly on the electrons that are separated from the ions to create a double layer (DL). This DL is accelerated into the target, like a piston that pushes the matter in such a way that a shock wave is created. Here we discuss two novel ideas. First is the transition domain between the relativistic and non-relativistic laser induced shock waves. Our solution is based on relativistic hydrodynamics also for the above transition domain. The relativistic shock wave parameters, such as compression, pressure, shock wave and particle flow velocities, sound velocity and rarefaction wave velocity in the compressed target, and the temperature are calculated. Secondly, we would like to use this transition domain for shock wave induced ultrafast ignition of a pre-compressed target. The laser parameters...

Eliezer, Shalom; Pinhasi, Shirly Vinikman; Raicher, Erez; Val, José Maria Martinez

2014-01-01T23:59:59.000Z

231

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

SciTech Connect

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.

Unn-Toc, W.; Meier, C.; Halberstadt, N. [Laboratoire Collisions Agregats et Reactivite, IRSAMC, UMR CNRS 5589, Universite Paul Sabatier, 31062 Toulouse (France); Uranga-Pina, Ll. [Laboratoire Collisions Agregats et Reactivite, IRSAMC, UMR CNRS 5589, Universite Paul Sabatier, 31062 Toulouse (France); Facultad de Fisica, Universidad de la Habana, San Lazaro y L, Vedado, 10400 La Habana (Cuba); Rubayo-Soneira, J. [Instituto Superior de Tecnologias y Ciencias Aplicadas (InSTEC), Ave. Salvador Allende y Luaces, Habana 10600, AP 6163 La Habana (Cuba)

2012-08-07T23:59:59.000Z

232

Electron diffraction using ultrafast electron bunches from a laser-wakefield accelerator at kHz repetition rate  

SciTech Connect

We show that electron bunches in the 50-100 keV range can be produced from a laser wakefield accelerator using 10 mJ, 35 fs laser pulses operating at 0.5 kHz. It is shown that using a solenoid magnetic lens, the electron bunch distribution can be shaped. The resulting transverse and longitudinal coherence is suitable for producing diffraction images from a polycrystalline 10 nm aluminum foil. The high repetition rate, the stability of the electron source, and the fact that its uncorrelated bunch duration is below 100 fs make this approach promising for the development of sub-100 fs ultrafast electron diffraction experiments.

He, Z.-H.; Thomas, A. G. R.; Nees, J. A.; Hou, B.; Krushelnick, K. [Center for Ultrafast Optical Science, University of Michigan, Ann Arbor, Michigan 48106-2099 (United States)] [Center for Ultrafast Optical Science, University of Michigan, Ann Arbor, Michigan 48106-2099 (United States); Beaurepaire, B.; Malka, V.; Faure, J. [Laboratoire d'Optique Appliquee, ENSTA-CNRS-Ecole Polytechnique, UMR 7639, 91761 Palaiseau (France)] [Laboratoire d'Optique Appliquee, ENSTA-CNRS-Ecole Polytechnique, UMR 7639, 91761 Palaiseau (France)

2013-02-11T23:59:59.000Z

233

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

SciTech Connect

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.

Yazaki, Akio [Department of Electrical Engineering, University of California, Los Angeles, California 90095 (United States); Yokohama Research Laboratory, Hitachi, Ltd., Kanagawa 244-0817 (Japan); Kim, Chanju [Department of Electrical Engineering, University of California, Los Angeles, California 90095 (United States); Advanced Photonics Research Institute, Gwangju Institute of Science and Technology, Gwangju 500-712 (Korea, Republic of); Chan, Jacky [Department of Electrical Engineering, University of California, Los Angeles, California 90095 (United States); Mahjoubfar, Ata [Department of Electrical Engineering, University of California, Los Angeles, California 90095 (United States); California NanoSystems Institute, University of California, Los Angeles, California 90095 (United States); Goda, Keisuke, E-mail: goda@chem.s.u-tokyo.ac.jp [Department of Electrical Engineering, University of California, Los Angeles, California 90095 (United States); Department of Chemistry, University of Tokyo, Tokyo 113-0033 (Japan); Watanabe, Masahiro [Yokohama Research Laboratory, Hitachi, Ltd., Kanagawa 244-0817 (Japan); Jalali, Bahram [Department of Electrical Engineering, University of California, Los Angeles, California 90095 (United States); California NanoSystems Institute, University of California, Los Angeles, California 90095 (United States); Department of Bioengineering, University of California, Los Angeles, California 90095 (United States); Department of Surgery, David Geffen School of Medicine, University of California, Los Angeles, California 90095 (United States)

2014-06-23T23:59:59.000Z

234

Ultrafast terahertz-induced response of GeSbTe phase-change materials Michael J. Shu,1,2,a)  

E-Print Network (OSTI)

Ultrafast terahertz-induced response of GeSbTe phase-change materials Michael J. Shu,1,2,a) Peter-optically, pumping with single-cycle terahertz pulses as a means of biasing phase-change materials on a sub of these materials is important for predicting the field-driven heating and phase-change behavior. However

235

Ultrafast Infrared Heating Laser Pulse-Induced Micellization Kinetics of Poly(ethylene oxide)-Poly(propylene oxide)-Poly(ethylene oxide) in  

E-Print Network (OSTI)

Ultrafast Infrared Heating Laser Pulse-Induced Micellization Kinetics of Poly(ethylene oxide)-Poly(propylene oxide)-Poly(ethylene oxide) in Water Xiaodong Ye, Yijie Lu, Shilin Liu,*, Guangzhao Zhang, and Chi Wu-induced micellization of poly(ethylene oxide)-b-poly(propylene oxide)-b-poly(ethylene oxide) (Pluronic PE10300) triblock

Liu, Shilin

236

The Influence of Chain Dynamics on the Far Infrared Spectrum of Liquid Methanol-Water Mixtures  

SciTech Connect

Far-infrared absorption spectroscopy has been used to study the low frequency ({center_dot} 100 cm{sup -1}) intermolecular modes of methanol in mixtures with water. With the aid of a first principles molecular dynamics simulation on an equivalent system, a detailed understanding about the origin of the low frequency IR modes has been established. The total dipole spectrum from the simulation suggests that the bands appearing in the experimental spectra at approximately 55 cm{sup -1} and 70 cm{sup -1} in methanol and methanol-rich mixtures arise from both fluctuations and torsional motions occurring within the methanol hydrogen-bonded chains. The influence of these modes on both the solvation dynamics and the relaxation mechanisms in the liquid are discussed within the context of recent experimental and theoretical results that have emerged from studies focusing on the short time dynamics in the methanol hydrogen bond network.

Woods, K.N.; /Stanford U., Phys. Dept.; Wiedemann, H.; /SLAC, SSRL; ,

2005-07-12T23:59:59.000Z

237

Test of the Gouy-Chapman Theory for a Charged Lipid Membrane against Explicit-Solvent Molecular Dynamics Simulations  

Science Journals Connector (OSTI)

A wealth of experimental data has verified the applicability of the Gouy-Chapman (GC) theory to charged lipid membranes. Surprisingly, a validation of GC by molecular dynamics (MD) simulations has been elusive. Here, we report a test of GC against extensive MD simulations of an anionic lipid bilayer solvated by water at different concentrations of NaCl or KCl. We demonstrate that the ion distributions from the simulations agree remarkably well with GC predictions when information on the adsorption of counterions to the bilayer is incorporated.

Myunggi Yi; Hugh Nymeyer; Huan-Xiang Zhou

2008-07-18T23:59:59.000Z

238

Solvent Dependence on Bond Length Alternation and Charge Distribution in Phenol Blue: A Car?Parrinello Molecular Dynamics Investigation  

Science Journals Connector (OSTI)

Solvent Dependence on Bond Length Alternation and Charge Distribution in Phenol Blue: A Car?Parrinello Molecular Dynamics Investigation ... (4) The probing nature of these molecules is due to the effect of the polarity of the solvation shell in changing the electron excitation energy of the indicator dye. ... (23) The usual theoretical approach to tune the bond length alternation was to apply a static electric field(20, 25) or to optimize the structure by placing “sparkles” (negative or positive ions) close to the donor or acceptor groups of these conjugated systems. ...

N. Arul Murugan; Zilvinas Rinkevicius; Hans Ågren

2009-04-02T23:59:59.000Z

239

Time-Resolved Molecular Frame Dynamics of Fixed-in-Space CS2 Molecules  

SciTech Connect

Random orientation of molecules within a sample leads to blurred observationsof chemical reactions studied from the laboratory perspective. Methodsdeveloped for the dynamic imaging of molecular structures and processesstruggle with this, as measurements are optimally made in the molecular frame.Here we uselaser alignment to transiently fix CS2 molecules in space longenough to elucidate, in the molecular reference frame, details of ultrafast electronic vibrationaldynamics during a photochemical reaction. These three-dimensional photoelectron imaging results, combined with ongoing efforts in molecular alignment and orientation, presage a wide range of insights obtainable fromtime-resolved studies in the molecular frame.

Bisgaard, Christer; Clarkin, Owen; Wu, Guorong; Lee, Anthony; Gessner, Oliver; Hayden, Carl; Stolow, Albert

2009-04-02T23:59:59.000Z

240

Dynamic Solvation in Imidazolium-Based Ionic Liquids on Short Time Scales Lindsay Sanders Headley, Prasun Mukherjee, Jared L. Anderson, Rongfang Ding,  

E-Print Network (OSTI)

"green" solvents by reducing environmental levels of volatile organic carbons. Their viscosities can coumarin 153 in two imidazoles, six imidazolium- based ionic liquids, and several other solvents and an inorganic anion. They have been used as novel solvent systems for organic synthesis,1-14 liquid

Song, Xueyu

Note: This page contains sample records for the topic "ultrafast solvation dynamics" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


241

Dynamic Solvation in Room-Temperature Ionic Liquids P. K. Chowdhury, M. Halder, L. Sanders, T. Calhoun, J. L. Anderson, D. W. Armstrong,  

E-Print Network (OSTI)

. Calhoun, J. L. Anderson, D. W. Armstrong, X. Song, and J. W. Petrich* Department of Chemistry, Iowa State

Song, Xueyu

242

Anion photoelectron spectroscopy of solvated transition state precursors Harry Gomez, Giovanni Meloni, James Madrid, and Daniel M. Neumark  

E-Print Network (OSTI)

and theoretical studies on transition state spectros- copy of isolated gas phase reactions, yielding new insights of how transition state spectroscopy and dynamics would differ in a condensed phase environment.6 transition state. We have previously shown that PE spectroscopy of stable negative ions can be used to study

Neumark, Daniel M.

243

Structure and dynamics of aqueous solution of uranyl ions  

SciTech Connect

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 Å around the uranium atom, whereas the hydrogen atoms of water are distributed around the uranium atom with the major peak at around 3.0 Å. 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.

Chopra, Manish [Radiation Safety Systems Division, Bhabha Atomic Research Centre, Mumbai-400085 (India); Choudhury, Niharendu, E-mail: nihcho@barc.gov.in [Theoretical Chemistry Section, Bhabha Atomic Research Centre, Mumbai-400085 (India)

2014-04-24T23:59:59.000Z

244

Multiple time step integrators in ab initio molecular dynamics  

SciTech Connect

Multiple time-scale algorithms exploit the natural separation of time-scales in chemical systems to greatly accelerate the efficiency of molecular dynamics simulations. Although the utility of these methods in systems where the interactions are described by empirical potentials is now well established, their application to ab initio molecular dynamics calculations has been limited by difficulties associated with splitting the ab initio potential into fast and slowly varying components. Here we present two schemes that enable efficient time-scale separation in ab initio calculations: one based on fragment decomposition and the other on range separation of the Coulomb operator in the electronic Hamiltonian. We demonstrate for both water clusters and a solvated hydroxide ion that multiple time-scale molecular dynamics allows for outer time steps of 2.5 fs, which are as large as those obtained when such schemes are applied to empirical potentials, while still allowing for bonds to be broken and reformed throughout the dynamics. This permits computational speedups of up to 4.4x, compared to standard Born-Oppenheimer ab initio molecular dynamics with a 0.5 fs time step, while maintaining the same energy conservation and accuracy.

Luehr, Nathan; Martínez, Todd J. [Department of Chemistry, Stanford University, Stanford, California 94305 (United States) [Department of Chemistry, Stanford University, Stanford, California 94305 (United States); The PULSE Institute, Stanford University, Stanford, California 94305 (United States); SLAC National Accelerator Laboratory, Menlo Park, California 94025 (United States); Markland, Thomas E. [Department of Chemistry, Stanford University, Stanford, California 94305 (United States)] [Department of Chemistry, Stanford University, Stanford, California 94305 (United States)

2014-02-28T23:59:59.000Z

245

Theoretical Simulations and Ultrafast Pump-probe Spectroscopy Experiments in Pigment-protein Photosynthetic Complexes  

SciTech Connect

Theoretical simulations and ultrafast pump-probe laser spectroscopy experiments were used to study photosynthetic pigment-protein complexes and antennae found in green sulfur bacteria such as Prosthecochloris aestuarii, Chloroflexus aurantiacus, and Chlorobium tepidum. The work focused on understanding structure-function relationships in energy transfer processes in these complexes through experiments and trying to model that data as we tested our theoretical assumptions with calculations. Theoretical exciton calculations on tubular pigment aggregates yield electronic absorption spectra that are superimpositions of linear J-aggregate spectra. The electronic spectroscopy of BChl c/d/e antennae in light harvesting chlorosomes from Chloroflexus aurantiacus differs considerably from J-aggregate spectra. Strong symmetry breaking is needed if we hope to simulate the absorption spectra of the BChl c antenna. The theory for simulating absorption difference spectra in strongly coupled photosynthetic antenna is described, first for a relatively simple heterodimer, then for the general N-pigment system. The theory is applied to the Fenna-Matthews-Olson (FMO) BChl a protein trimers from Prosthecochloris aestuarii and then compared with experimental low-temperature absorption difference spectra of FMO trimers from Chlorobium tepidum. Circular dichroism spectra of the FMO trimer are unusually sensitive to diagonal energy disorder. Substantial differences occur between CD spectra in exciton simulations performed with and without realistic inhomogeneous distribution functions for the input pigment diagonal energies. Anisotropic absorption difference spectroscopy measurements are less consistent with 21-pigment trimer simulations than 7-pigment monomer simulations which assume that the laser-prepared states are localized within a subunit of the trimer. Experimental anisotropies from real samples likely arise from statistical averaging over states with diagonal energies shifted by in homogeneous broadening and as such, are quite sensitive to diagonal energy disorder. The experimental anisotropies exhibit strong oscillations with {approximately}220 fs period for certain wavelengths in one-color absorption difference experiments. The oscillations only appear when the laser pulse spectrum overlaps both of the lowest-energy groups of exciton levels clustered near 815 and 825 nm. Results suggest that the oscillations stem from quantum beating between exciton levels, rather than from coherent nuclear motion.

Buck, D.R.

2000-09-12T23:59:59.000Z

246

Teasing Out the Nature of Structural Instabilities in Ceramic Compounds |  

NLE Websites -- All DOE Office Websites (Extended Search)

Doubling Estimates of Light Elements in the Earth's Core Doubling Estimates of Light Elements in the Earth's Core A New Material for Warm-White LEDs Probing Ultrafast Solvation Dynamics with High Repetition-Rate Laser/X-ray Methodologies Ultrafast X-Ray Spectroscopy as a Probe of Nonequilibrium Dynamics in Ruthenium Complexes The Electronic Origin of Photoinduced Strain Science Highlights Archives: 2013 | 2012 | 2011 | 2010 2009 | 2008 | 2007 | 2006 2005 | 2004 | 2003 | 2002 2001 | 2000 | 1998 | Subscribe to APS Science Highlights rss feed Teasing Out the Nature of Structural Instabilities in Ceramic Compounds MARCH 12, 2013 Bookmark and Share The simple perovskite structure of EuTiO3 illustrated above shows the essential competing structural instabilities. At the center of the figure is the oxygen cage rotation, and to the right is the central titanium

247

Ultrafast single-electron transfer in coupled quantum dots driven by a few-cycle chirped pulse  

SciTech Connect

We theoretically study the ultrafast transfer of a single electron between the ground states of a coupled double quantum dot (QD) structure driven by a nonlinear chirped few-cycle laser pulse. A time-dependent Schrödinger equation without the rotating wave approximation is solved numerically. We demonstrate numerically the possibility to have a complete transfer of a single electron by choosing appropriate values of chirped rate parameters and the intensity of the pulse. Even in the presence of the spontaneous emission and dephasing processes of the QD system, high-efficiency coherent transfer of a single electron can be obtained in a wide range of the pulse parameters. Our results illustrate the potential to utilize few-cycle pulses for the excitation in coupled quantum dot systems through the nonlinear chirp parameter control, as well as a guidance in the design of experimental implementation.

Yang, Wen-Xing, E-mail: wenxingyang2@126.com [Department of Physics, Southeast University, Nanjing 210096 (China); Institute of Photonics Technologies, National Tsing-Hua University, Hsinchu 300, Taiwan (China); Chen, Ai-Xi [Department of Applied Physics, School of Basic Science, East China Jiaotong University, Nanchang 330013 (China); Bai, Yanfeng [Department of Physics, Southeast University, Nanjing 210096 (China); Lee, Ray-Kuang [Institute of Photonics Technologies, National Tsing-Hua University, Hsinchu 300, Taiwan (China)

2014-04-14T23:59:59.000Z

248

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

SciTech Connect

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.

Hamad, Syed [School of Physics, University of Hyderabad, Prof. C. R. Rao Road, Hyderabad 500046 (India); Podagatlapalli, G. Krishna; Soma, Venugopal Rao, E-mail: svrsp@uohyd.ernet.in, E-mail: soma-venu@yahoo.com [Advanced Center of Research in High Energy Materials (ACRHEM), University of Hyderabad, Prof. C. R. Rao Road, Hyderabad 500046 (India); Mohiddon, Md. Ahamad [Center for Nanotechnology, University of Hyderabad, Prof. C. R. Rao Road, Hyderabad 500046 (India)

2014-06-30T23:59:59.000Z

249

Role of surface states and defects in the ultrafast nonlinear optical properties of CuS quantum dots  

SciTech Connect

We report facile preparation of water dispersible CuS quantum dots (2–4 nm) and nanoparticles (5–11 nm) through a nontoxic, green, one-pot synthesis method. Optical and microstructural studies indicate the presence of surface states and defects (dislocations, stacking faults, and twins) in the quantum dots. The smaller crystallite size and quantum dot formation have significant effects on the high energy excitonic and low energy plasmonic absorption bands. Effective two-photon absorption coefficients measured using 100 fs laser pulses employing open-aperture Z-scan in the plasmonic region of 800 nm reveal that CuS quantum dots are better ultrafast optical limiters compared to CuS nanoparticles.

Mary, K. A. Ann; Unnikrishnan, N. V., E-mail: nvu100@yahoo.com [School of Pure and Applied Physics, Mahatma Gandhi University, Kottayam 686560 (India); Philip, Reji [Light and Matter Physics Group, Raman Research Institute, C.V. Raman Avenue, Sadashivanagar, Bangalore 560080 (India)

2014-07-01T23:59:59.000Z

250

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

DOE Patents (OSTI)

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.

Heebner, John E. (Livermore, CA)

2010-08-03T23:59:59.000Z

251

Charge-Dependent Cavity Radii for an Accurate Dielectric Continuum Model of Solvation with Emphasis on Ions: Aqueous Solutes with Oxo, Hydroxo, Amino, Methyl, Chloro, Bromo and Fluoro Functionalities  

SciTech Connect

Dielectric continuum solvation models are widely used because they are a computationally efficacious way to simulate equilibrium properties of solutes. With advances that allow for molecular-shaped cavities, they have reached a high level of accuracy, in particular for neutral solutes. However, benchmark tests show that existing schemes for defining cavities are unable to consistently predict accurately the effects of solvation on ions, especially anions. This work involves the further development of a protocol put forth earlier for defining the cavities of aqueous solutes, with resulting advances that are most striking for anions. Molecular cavities are defined as interlocked spheres around atoms or groups of atoms in the solute, but the sphere radii are determined by simple empirically-based expressions involving the effective atomic charges of the solute atoms (derived from molecular electrostatic potential) and base radii. Both of these terms are optimized for the different types of atoms or functional groups in a training set of neutral and charged solutes. Parameters in these expressions for radii were fitted by minimizing residuals between calculated and measured standard free energies of solvation (?Gs*), weighted by the uncertainty in the measured value. The calculations were performed using density functional theory with the B3LYP functional and the 6-311+G** basis set and the COnductor-like Screening MOdel (COSMO). The optimized radii definitions reproduce ?Gs* of neutral solutes and singly-charged ions in the training set to within experimental uncertainty and, more importantly, accurately predict ?Gs* of compounds outside the training set, in particular anions. Inherent to this approach, the cavity definitions reflect the strength of specific solute-water interactions. We surmise that this feature underlies the success of the model, referred to as the CD-COSMO model for Charge-Dependent (also Camaioni-Dupuis) COSMO model. These findings offer encouragement that we can keep extending this scheme to other functional groups and obtain better accuracy in using continuum solvation models to predict equilibrium properties of aqueous ionic solutes. The approach is illustrated for a number of test cases, including the determination of acidities of an amine base and a study of the tautomerization equilibrium of a zwitterionic molecule (glycine). The approach is also extended to calculating solvation energies of transition states toward a full characterization of reaction pathways in aqueous phase, here in SN2 exchange reactions. The calculated reactions barriers in aqueous solution are in excellent agreement with experimental values. 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.

Ginovska, Bojana; Camaioni, Donald M.; Dupuis, Michel; Schwerdtfeger, Christine A.; Gilcrease, Quinn

2008-10-23T23:59:59.000Z

252

Electronic Coupling Dependence of Ultrafast Interfacial Electron Transfer on Nanocrystalline Thin Films and Single Crystal  

SciTech Connect

The long-term goal of the proposed research is to understand electron transfer dynamics in nanoparticle/liquid interface. This knowledge is essential to many semiconductor nanoparticle based devices, including photocatalytic waste degradation and dye sensitized solar cells.

Lian, Tianquan

2014-04-22T23:59:59.000Z

253

Water adsorption, solvation and deliquescence of alkali halide thin films on SiO2 studied by ambient pressure X-ray photoelectron spectroscopy  

SciTech Connect

The adsorption of water on KBr thin films evaporated onto SiO2 was investigated as a function of relative humidity (RH) by ambient pressure X-ray photoelectron spectroscopy. At 30percent RH adsorbed water reaches a coverage of approximately one monolayer. As the humidity continues to increase, the coverage of water remains constant or increases very slowly until 60percent RH, followed by a rapid increase up to 100percent RH. At low RH a significant number of the Br atoms are lost due to irradiation damage. With increasing humidity solvation increases ion mobility and gives rise to a partial recovery of the Br/K ratio. Above 60percent RH the increase of the Br/K ratio accelerates. Above the deliquescence point (85percent RH), the thickness of the water layer continues to increase and reaches more than three layers near saturation. The enhancement of the Br/K ratio at this stage is roughly a factor 2.3 on a 0.5 nm KBr film, indicating a strong preferential segregation of Br ions to the surface of the thin saline solution on SiO2.

Arima, Kenta; Jiang, Peng; Deng, Xingyi; Bluhm, Henrik; Salmeron, Miquel

2010-03-31T23:59:59.000Z

254

Photo-Induced Spin-State Conversion in Solvated Transition Metal Complexes Probed via Time-Resolved Soft X-ray Spectroscopy  

SciTech Connect

Solution-phase photoinduced low-spin to high-spin conversion in the FeII polypyridyl complex [Fe(tren(py)3)]2+ (where tren(py)3 is tris(2-pyridylmethyliminoethyl)amine) has been studied via picosecond soft X-ray spectroscopy. Following 1A1 --> 1MLCT (metal-to-ligand charge transfer) excitation at 560 nm, changes in the iron L2- and L3-edges were observed concomitant with formation of the transient high-spin 5T2 state. Charge-transfer multiplet calculations coupled with data acquired on low-spin and high-spin model complexes revealed a reduction in ligand field splitting of 1 eV in the high-spin state relative to the singlet ground state. A significant reduction in orbital overlap between the central Fe-3d and the ligand N-2p orbitals was directly observed, consistent with the expected ca. 0.2 Angstrom increase in Fe-N bond length upon formation of the high-spin state. The overall occupancy of the Fe-3d orbitals remains constant upon spin crossover, suggesting that the reduction in sigma-donation is compensated by significant attenuation of pi-back-bonding in the metal-ligand interactions. These results demonstrate the feasibility and unique potential of time-resolved soft X-ray absorption spectroscopy to study ultrafast reactions in the liquid phase by directly probing the valence orbitals of first-row metals as well as lighter elements during the course of photochemical transformations.

Huse, Nils; Kim, Tae Kyu; Jamula, Lindsey; McCusker, James K.; de Groot, Frank M. F.; Schoenlein, Robert W.

2010-04-30T23:59:59.000Z

255

Ultra-Fast Fluorescence Imaging in Vivo with Conjugated Polymer Fluorophores in the Second Near-Infrared Window  

E-Print Network (OSTI)

In vivo fluorescence imaging in the second near-infrared window (1.0-1.7 microns) can afford deep tissue penetration and high spatial resolution, owing to the reduced scattering of long-wavelength photons. Here, we synthesize a series of low-bandgap donor/acceptor copolymers with tunable emission wavelengths of 1050-1350 nm in this window. Non-covalent functionalization with phospholipid-polyethylene glycol results in water-soluble and biocompatible polymeric nanoparticles, allowing for live cell molecular imaging at > 1000 nm with polymer fluorophores for the first time. Importantly, the high quantum yield of the polymer allows for in vivo, deep-tissue and ultrafast imaging of mouse arterial blood flow with an unprecedented frame rate of > 25 frames per second. The high time resolution results in spatially and time resolved imaging of the blood flow pattern in cardiogram waveform over a single cardiac cycle (~ 200 ms) of a mouse, which has not been observed with fluorescence imaging in this window before.

Hong, Guosong; Antaris, Alexander L; Diao, Shuo; Wu, Di; Cheng, Kai; Zhang, Xiaodong; Chen, Changxin; Liu, Bo; He, Yuehui; Wu, Justin Z; Yuan, Jun; Zhang, Bo; Tao, Zhimin; Fukunaga, Chihiro; Dai, Hongjie

2014-01-01T23:59:59.000Z

256

The origin of ultra-fast outflows in AGN: Monte-Carlo simulations of the wind in PDS 456  

E-Print Network (OSTI)

Ultra-fast outflows (UFOs) are seen in many AGN, giving a possible mode for AGN feedback onto the host galaxy. However, the mechanism(s) for the launch and acceleration of these outflows are currently unknown, with UV line driving apparently strongly disfavoured as the material along the line of sight is so highly ionised that it has no UV transitions. We revisit this issue using the Suzaku X-ray data from PDS 456, an AGN with the most powerful UFO seen in the local Universe. We explore conditions in the wind by developing a new 3-D Monte-Carlo code for radiation transport. The code only handles highly ionised ions, but the data show the ionisation state of the wind is high enough that this is appropriate, and this restriction makes it fast enough to explore parameter space. We reproduce the results of earlier work, confirming that the mass loss rate in the wind is around 30% of the inferred inflow rate through the outer disc. We show for the first time that UV line driving is likely to be a major contributio...

Hagino, Kouichi; Done, Chris; Gandhi, Poshak; Watanabe, Shin; Sako, Masao; Takahashi, Tadayuki

2014-01-01T23:59:59.000Z

257

In-situ weak-beam and polarization control of multidimensional laser sidebands for ultrafast optical switching  

SciTech Connect

All-optical switching has myriad applications in optoelectronics, optical communications, and quantum information technology. To achieve ultrafast optical switching in a compact yet versatile setup, we demonstrate distinct sets of two-dimensional (2D) broadband up-converted multicolor arrays (BUMAs) in a thin type-I ?-barium-borate crystal with two noncollinear near-IR femtosecond pulses at various phase-matching conditions. The unique interaction mechanism is revealed as quadratic spatial solitons (QSSs)-coupled cascaded four-wave mixing (CFWM), corroborated by numerical calculations of the governing phase-matching conditions. Broad and continuous spectral-spatial tunability of the 2D BUMAs are achieved by varying the time delay between the two incident pulses that undergo CFWM interaction, rooted in the chirped nature of the weak white light and the QSSs generation of the intense fundamental beam. The control of 2D BUMAs is accomplished via seeding a weak second-harmonic pulse in situ to suppress the 2D arrays with polarization dependence on the femtosecond timescale that matches the control pulse duration of ?35 fs. A potential application is proposed on femtosecond all-optical switching in an integrated wavelength-time division multiplexing device.

Liu, Weimin; Wang, Liang; Fang, Chong, E-mail: Chong.Fang@oregonstate.edu [Department of Chemistry, Oregon State University, Corvallis, Oregon 97331 (United States)

2014-03-17T23:59:59.000Z

258

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

SciTech Connect

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.

Dong, Futao, E-mail: dongft@sina.com [The State Key Laboratory of Rolling and Automation, Northeastern University, Shenyang 110819 (China); Du, Linxiu; Liu, Xianghua [The State Key Laboratory of Rolling and Automation, Northeastern University, Shenyang 110819 (China); Xue, Fei [College of Electrical Engineering, Hebei United University, Tangshan 063000 (China)

2013-10-15T23:59:59.000Z

259

Ultrafast Internal Conversion in Ethylene. II. Mechanisms and Pathways for Quenching and Hydrogen Elimination  

E-Print Network (OSTI)

Through a combined experimental and theoretical approach, we study the nonadiabatic dynamics of the prototypical ethylene (C$_2$H$_4$) molecule upon $\\pi \\rightarrow \\pi^*$ excitation with 161 nm light. Using a novel experimental apparatus, we combine femtosecond pulses of vacuum ultraviolet (VUV) and extreme ultraviolet (XUV) radiation with variable delay to perform time resolved photo-ion fragment spectroscopy. In this second part of a two part series, the extreme ultraviolet (17 eV$ ethylene (CH$_2$CH$_2$) and ethylidene (CH$_3$CH) like geometries are observed within 100 fs after $\\pi...

Allison, T K; Glover, W J; Wright, T W; Stooke, A M; Khurmi, C; van Tilborg, J; Liu, Y; Falcone, R W; Martinez, T J; Belkacem, A

2011-01-01T23:59:59.000Z

260

Dynamics of water in the amphiphilic pore of amyloid β fibrils  

NLE Websites -- All DOE Office Websites (Extended Search)

water water in the amphiphilic pore of amyloid b fibrils q Pavan K. GhattyVenkataKrishna a,⇑ , Barmak Mostofian b a Computational Biology and Bioinformatics Group and BioEnergy Science Center, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA b UT/ORNL Center for Molecular Biophysics, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA a r t i c l e i n f o Article history: Available online 19 July 2013 a b s t r a c t Alzheimers disease related amyloid peptide, Ab, forms a fibrillar structure through aggregation. The aggregate is stabilized by a salt bridge that is responsible for the formation of an amphiphilic pore that can accommodate water molecules. None of the reported structures of Ab, however, contain water. We present results from molecular dynamics simulations on dimeric Ab fibrils solvated in water. Water pen- etrates and fills the amphiphilic pore increasing its volume.

Note: This page contains sample records for the topic "ultrafast solvation dynamics" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


261

Photo-Induced Spin-State Conversion in Solvated Transition Metal Complexes Probed via Time-Resolved Soft X-ray  

E-Print Network (OSTI)

, Michigan 48824, Department of Chemistry, Utrecht UniVersity, 3584 CA Utrecht, Netherlands, and Material widely applied for elucidating chemical dynamics at the molecular level by probing vibrational

McCusker, James K.

262

Cavity ring-up spectroscopy for ultrafast sensing with optical microresonators  

E-Print Network (OSTI)

Spectroscopy of whispering-gallery mode (WGM) microresonators has become a powerful scientific tool, enabling detection of single viruses, nanoparticles, and even single molecules. Yet the demonstrated timescale of these schemes has been limited so far to milliseconds or more. Here we introduce a novel scheme that is orders of magnitude faster, capable of capturing complete spectral snapshots of WGM resonances at nanosecond timescales: cavity ring-up spectroscopy (CRUS). Based on sharply-rising detuned probe pulses, CRUS combines the sensitivity of heterodyne measurements with the highest possible, transform-limited acquisition rate. As a demonstration we capture spectra of microtoroid resonators at time intervals as short as 16 ns, directly monitoring sub-microsecond dynamics of their optomechanical vibrations, thermorefractive response and Kerr nonlinearity. CRUS holds promise for the study of fast biological processes such as enzyme kinetics, protein folding and light harvesting, with applications in other...

Rosenblum, Serge; Arazi, Lior; Vollmer, Frank; Dayan, Barak

2015-01-01T23:59:59.000Z

263

Biosystem Dynamics & Design | EMSL  

NLE Websites -- All DOE Office Websites (Extended Search)

Biosystem Dynamics & Design Overview Atmospheric Aerosol Systems Biosystem Dynamics & Design Energy Materials & Processes Terrestrial & Subsurface Ecosystems Biosystem Dynamics &...

264

Ultrafast observation of critical nematic fluctuations and giant magnetoelastic coupling in iron pnictides  

SciTech Connect

Many of the iron pnictides have strongly anisotropic normal-state characteristics, important for the exotic magnetic and superconducting behaviour these materials exhibit. Y et, the origin of the observed anisotropy is unclear. Electronically driven nematicity has been suggested, but distinguishing this as an independent degree of freedom from magnetic and structural orders is dif?cult, as these couple together to break the same tetragonal symmetry. Here we use time-resolved polarimetry to reveal critical nematic ?uctuations in unstrained Ba(Fe1 À xCox)2As2. The femtosecond anisotropic response, which arises from the two-fold in-plane anisotropy of the complex refractive index, displays a characteristic two-step recovery absent in the isotropic response. The fast recovery appears only in the magnetically ordered state, whereas the slow one persists in the paramagnetic phase with a critical divergence approaching the structural transition temperature. The dynamics also reveal a gigantic magnetoelastic coupling that far exceeds electron–spin and electron–phonon couplings, opposite to conventional magnetic metals.

Patz, Aaron [Ames Laboratory; Li, Tianqi [Ames Laboratory; ran, Sheng [Ames Laboratory; Fernandes, Rafael M. [University of Minnesota; Schmalian, Joerg [Karlsruhe Institute of Technology; Budko, Sergey L. [Ames Laboratory; Canfield, Paul C. [Ames Laboratory; Perakis, Ilias E. [University of Crete; Wang, Jigang [Ames Laboratory

2014-02-06T23:59:59.000Z

265

In situ imaging of ultra-fast loss of nanostructure in nanoparticle aggregates  

SciTech Connect

The word “nanoparticle” nominally elicits a vision of an isolated sphere; however, the vast bulk of nanoparticulate material exists in an aggregated state. This can have significant implications for applications such as combustion, catalysis, and optical excitation, where particles are exposed to high temperature and rapid heating conditions. In such environments, particles become susceptible to morphological changes which can reduce surface area, often to the detriment of functionality. Here, we report on thermally-induced coalescence which can occur in aluminum nanoparticle aggregates subjected to rapid heating (10{sup 6}–10{sup 11}?K/s). Using dynamic transmission electron microscopy, we observed morphological changes in nanoparticle aggregates occurring in as little as a few nanoseconds after the onset of heating. The time-resolved probes reveal that the morphological changes initiate within 15?ns and are completed in less than 50?ns. The morphological changes were found to have a threshold temperature of about 1300?±?50?K, as determined by millisecond-scale experiments with a calibrated heating stage. The temperature distribution of aggregates during laser heating was modeled with various simulation approaches. The results indicate that, under rapid heating conditions, coalescence occurs at an intermediate temperature between the melting points of aluminum and the aluminum oxide shell, and proceeds rapidly once this threshold temperature is reached.

Egan, Garth C. [Department of Materials Science, University of Maryland, College Park, Maryland 20742 (United States); Sullivan, Kyle T.; LaGrange, Thomas; Reed, Bryan W. [Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, California 94550 (United States); Zachariah, Michael R., E-mail: mrz@umd.edu [Department of Chemical and Biomolecular Engineering, University of Maryland, College Park, Maryland 20742 (United States); Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland 20742 (United States)

2014-02-28T23:59:59.000Z

266

Models for solvated biomolecular structures  

E-Print Network (OSTI)

Daggett, V. 2002. “Protein folding and unfolding at atomicunifying mechanism for protein folding. ” Proceedings of theV. 2004. “Prediction of protein folding rates from the amino

Cerutti, David

2007-01-01T23:59:59.000Z

267

Direct ab initio molecular dynamics study on a microsolvated S{sub N}2 reaction of OH{sup -}(H{sub 2}O) with CH{sub 3}Cl  

SciTech Connect

Reaction dynamics for a microsolvated S{sub N}2 reaction OH{sup -}(H{sub 2}O)+CH{sub 3}Cl have been investigated by means of the direct ab initio molecular dynamics method. The relative center-of-mass collision energies were chosen as 10, 15, and 25 kcal/mol. Three reaction channels were found as products. These are (1) a channel leading to complete dissociation (the products are CH{sub 3}OH+Cl{sup -}+H{sub 2}O: denoted by channel I), (2) a solvation channel (the products are Cl{sup -}(H{sub 2}O)+CH{sub 3}OH: channel II), and (3) a complex formation channel (the products are CH{sub 3}OH{center_dot}{center_dot}{center_dot}H{sub 2}O+Cl{sup -}: channel III). The branching ratios for the three channels were drastically changed as a function of center-of-mass collision energy. The ratio of complete dissociation channel (channel I) increased with increasing collision energy, whereas that of channel III decreased. The solvation channel (channel II) was minor at all collision energies. The selectivity of the reaction channels and the mechanism are discussed on the basis of the theoretical results.

Tachikawa, Hiroto [Division of Materials Chemistry, Graduate School of Engineering, Hokkaido University, Sapporo 060-8628 (Japan)

2006-10-07T23:59:59.000Z

268

Introduction Basic dynamics  

E-Print Network (OSTI)

Introduction Basic dynamics The Gulf Stream The thermohaline circulation Ocean currents: some Ocean currents: some misconceptions and some dynamics #12;Introduction Basic dynamics The Gulf Stream. Geosciences Ocean currents: some misconceptions and some dynamics #12;Introduction Basic dynamics The Gulf

LaCasce, Joseph H.

269

Dynamics of Confined Water Molecules in Aqueous Salt Hydrates  

SciTech Connect

The unusual properties of water are largely dictated by the dynamics of the H bond network. A single water molecule has more H bonding sites than atoms, hence new experimental and theoretical investigations about this peculiar liquid have not ceased to appear. Confinement of water to nanodroplets or small molecular clusters drastically changes many of the liquid’s properties. Such confined water plays a major role in the solvation of macro molecules such as proteins and can even be essential to their properties. Despite the vast results available on bulk and confined water, discussions about the correlation between spectral and structural properties continue to this day. The fast relaxation of the OH stretching vibration in bulk water, and the variance of sample geometries in the experiments on confined water obfuscate definite interpretation of the spectroscopic results in terms of structural parameters. We present first time-resolved investigations on a new model system that is ideally suited to overcome many of the problems faced in spectroscopical investigation of the H bond network of water. Aqueous hydrates of inorganic salts provide water molecules in a crystal grid, that enables unambiguous correlations of spectroscopic and structural features. Furthermore, the confined water clusters are well isolated from each other in the crystal matrix, so different degrees of confinement can be achieved by selection of the appropriate salt.

Werhahn, Jasper C.; Pandelov, S.; Yoo, Soohaeng; Xantheas, Sotiris S.; Iglev, H.

2011-04-01T23:59:59.000Z

270

An Efficient Quantum Jump Method for Coherent Energy Transfer Dynamics in Photosynthetic Systems under the Influence of Laser Fields  

E-Print Network (OSTI)

We present a non-Markovian quantum jump approach for simulating coherent energy transfer dynamics in molecular systems in the presence of laser fields. By combining a coherent modified Redfield theory (CMRT) and a non-Markovian quantum jump (NMQJ) method, this new approach inherits the broad-range validity from the CMRT and highly efficient propagation from the NMQJ. To implement NMQJ propagation of CMRT, we show that the CMRT master equation can be casted into a generalized Lindblad form. Moreover, we extend the NMQJ approach to treat time-dependent Hamiltonian, enabling the description of excitonic systems under coherent laser fields. As a benchmark of the validity of this new method, we show that the CMRT-NMQJ method accurately describes the energy transfer dynamics in a prototypical photosynthetic complex. Finally, we apply this new approach to simulate the quantum dynamics of a dimer system coherently excited to coupled single-excitation states under the influence of laser fields, which allows us to investigate the interplay between the photoexcitation process and ultrafast energy transfer dynamics in the system. We demonstrate that laser-field parameters significantly affect coherence dynamics of photoexcitations in excitonic systems, which indicates that the photoexcitation process must be explicitly considered in order to properly describe photon-induced dynamics in photosynthetic systems. This work should provide a valuable tool for efficient simulations of coherent control of energy flow in photosynthetic systems and artificial optoelectronic materials.

Qing Ai; Yuan-Jia Fan; Bih-Yaw Jin; Yuan-Chung Cheng

2014-04-19T23:59:59.000Z

271

Nonlinear ultrafast dynamics of high temperature YBa[subscript 2]Cu[subscript 3]O[subscript 7-?] superconductors probed with THz pump / THz probe spectroscopy  

E-Print Network (OSTI)

High power THz pulses induce near transparency in superconductive YBCO thin films below the critical temperature. THz pump/THz probe measurements reveal a decay of the induced transparency on the time scale of a few picoseconds.

Grady, N. K.

272

Symbolic dynamics  

E-Print Network (OSTI)

This chapter presents some of the links between automata theory and symbolic dynamics. The emphasis is on two particular points. The first one is the interplay between some particular classes of automata, such as local automata and results on embeddings of shifts of finite type. The second one is the connection between syntactic semigroups and the classification of sofic shifts up to conjugacy.

Béal, M -P; Eilers, S; Perrin, D

2010-01-01T23:59:59.000Z

273

Ultrafast Photoluminescence from Graphene  

Science Journals Connector (OSTI)

Since graphene has no band gap, photoluminescence is not expected from relaxed charge carriers. We have, however, observed significant light emission from graphene under excitation by ultrashort (30-fs) laser pulses. Light emission was found to occur across the visible spectral range (1.7–3.5 eV), with emitted photon energies exceeding that of the excitation laser (1.5 eV). The emission exhibits a nonlinear dependence on the laser fluence. In two-pulse correlation measurements, a dominant relaxation time of tens of femtoseconds is observed. A two-temperature model describing the electrons and their interaction with strongly coupled optical phonons can account for the experimental observations.

Chun Hung Lui (???); Kin Fai Mak; Jie Shan; Tony F. Heinz

2010-09-16T23:59:59.000Z

274

Ultrafast neutron detector  

DOE Patents (OSTI)

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.

Wang, C.L.

1985-06-19T23:59:59.000Z

275

Ultrafast neutron detector  

DOE Patents (OSTI)

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.

Wang, Ching L. (Livermore, CA)

1987-01-01T23:59:59.000Z

276

Introduction Dynamic Risk Measures  

E-Print Network (OSTI)

Introduction Dynamic Risk Measures Dynamic Risk Measures from BMO martingales Bid-Ask Dynamic Pricing Procedure Conclusion MESURES DE RISQUE DYNAMIQUES DYNAMIC RISK MEASURES Jocelyne Bion-Nadal CNRS Risk Measures Dynamic Risk Measures from BMO martingales Bid-Ask Dynamic Pricing Procedure Conclusion

Bion-Nadal, Jocelyne

277

Dynamic Positioning Simulator Dynamic Positioning Simulator  

E-Print Network (OSTI)

Simulator 5 / 24 #12;Dynamic Positioning Simulator Dynamic Positioning Why Dynamic Positioning? Advantages Dynamic Positioning: No tugboats needed; Offshore set-up is quick; Power saving; Precision situations more on Ship: Wind Force Fw = 1 2 air V 2 rw CXw (rw )AT 1 2 air V 2 rw CYw (rw )AL Mw = 1 2 air V 2 rw CMw (rw

Vuik, Kees

278

Charge constrained density functional molecular dynamics for simulation of condensed phase electron transfer reactions  

SciTech Connect

We present a plane-wave basis set implementation of charge constrained density functional molecular dynamics (CDFT-MD) for simulation of electron transfer reactions in condensed phase systems. Following the earlier work of Wu and Van Voorhis [Phys. Rev. A 72, 024502 (2005)], the density functional is minimized under the constraint that the charge difference between donor and acceptor is equal to a given value. The classical ion dynamics is propagated on the Born-Oppenheimer surface of the charge constrained state. We investigate the dependence of the constrained energy and of the energy gap on the definition of the charge and present expressions for the constraint forces. The method is applied to the Ru{sup 2+}-Ru{sup 3+} electron self-exchange reaction in aqueous solution. Sampling the vertical energy gap along CDFT-MD trajectories and correcting for finite size effects, a reorganization free energy of 1.6 eV is obtained. This is 0.1-0.2 eV lower than a previous estimate based on a continuum model for solvation. The smaller value for the reorganization free energy can be explained by the fact that the Ru-O distances of the divalent and trivalent Ru hexahydrates are predicted to be more similar in the electron transfer complex than for the separated aqua ions.

Oberhofer, Harald; Blumberger, Jochen [Department of Chemistry, University of Cambridge, Cambridge CB2 1EW (United Kingdom)

2009-08-14T23:59:59.000Z

279

Exploring size and state dynamics in CdSe quantum dots using two-dimensional electronic spectroscopy  

SciTech Connect

Development of optoelectronic technologies based on quantum dots depends on measuring, optimizing, and ultimately predicting charge carrier dynamics in the nanocrystal. In such systems, size inhomogeneity and the photoexcited population distribution among various excitonic states have distinct effects on electron and hole relaxation, which are difficult to distinguish spectroscopically. Two-dimensional electronic spectroscopy can help to untangle these effects by resolving excitation energy and subsequent nonlinear response in a single experiment. Using a filament-generated continuum as a pump and probe source, we collect two-dimensional spectra with sufficient spectral bandwidth to follow dynamics upon excitation of the lowest three optical transitions in a polydisperse ensemble of colloidal CdSe quantum dots. We first compare to prior transient absorption studies to confirm excitation-state-dependent dynamics such as increased surface-trapping upon excitation of hot electrons. Second, we demonstrate fast band-edge electron-hole pair solvation by ligand and phonon modes, as the ensemble relaxes to the photoluminescent state on a sub-picosecond time-scale. Third, we find that static disorder due to size polydispersity dominates the nonlinear response upon excitation into the hot electron manifold; this broadening mechanism stands in contrast to that of the band-edge exciton. Finally, we demonstrate excitation-energy dependent hot-carrier relaxation rates, and we describe how two-dimensional electronic spectroscopy can complement other transient nonlinear techniques.

Caram, Justin R.; Zheng, Haibin; Rolczynski, Brian S.; Griffin, Graham B.; Engel, Gregory S., E-mail: gsengel@uchicago.edu [Department of Chemistry, The Institute for Biophysical Dynamics, and The James Franck Institute, The University of Chicago, Chicago, Illinois 60637 (United States); Dahlberg, Peter D. [Graduate Program in the Biophysical Sciences, The Institute for Biophysical Dynamics, and The James Franck Institute, The University of Chicago, Chicago, Illinois 60637 (United States)] [Graduate Program in the Biophysical Sciences, The Institute for Biophysical Dynamics, and The James Franck Institute, The University of Chicago, Chicago, Illinois 60637 (United States); Dolzhnikov, Dmitriy S.; Talapin, Dmitri V. [Department of Chemistry and The James Franck Institute, The University of Chicago, Chicago, Illinois 60637 (United States)] [Department of Chemistry and The James Franck Institute, The University of Chicago, Chicago, Illinois 60637 (United States)

2014-02-28T23:59:59.000Z

280

Ultra-fast microwave-assisted hydrothermal synthesis of long vertically aligned ZnO nanowires for dye-sensitized solar cell application  

Science Journals Connector (OSTI)

Long vertically aligned ZnO nanowire arrays were synthesized using an ultra-fast microwave-assisted hydrothermal process. Using this method, we were able to grow ZnO nanowire arrays at an average growth rate as high as 200 nm min?1 for maximum microwave power level. This method does not suffer from the growth stoppage problem at long growth times that, according to our investigations, a normal microwave-assisted hydrothermal method suffers from. Longitudinal growth of the nanowire arrays was investigated as a function of microwave power level and growth time using cross-sectional FESEM images of the grown arrays. Effect of seed layer on the alignment of nanowires was also studied. X-ray diffraction analysis confirmed c-axis orientation and single-phase wurtzite structure of the nanowires. J–V curves of the fabricated ZnO nanowire-based mercurochrome-sensitized solar cells indicated that the short-circuit current density is increased with increasing the length of the nanowire array. According to the UV–vis spectra of the dyes detached from the cells, these increments were mainly attributed to the enlarged internal surface area and therefore dye loading enhancement in the lengthened nanowire arrays.

S M Mahpeykar; J Koohsorkhi; H Ghafoori-fard

2012-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "ultrafast solvation dynamics" from the National Library of EnergyBeta (NLEBeta).
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they are not comprehensive nor are they the most current set.
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to obtain the most current and comprehensive results.


281

Cybersecurity Dynamics Shouhuai Xu  

E-Print Network (OSTI)

Cybersecurity Dynamics Shouhuai Xu Department of Computer Science, University of Texas at San Antonio ABSTRACT We explore the emerging field of Cybersecurity Dynamics, a candidate foundation for the Science of Cybersecurity. Keywords Cybersecurity dynamics, security model, security analysis 1

Xu, Shouhuai

282

Scaling analysis of bio-molecular dynamics derived from elastic incoherent neutron scattering experiments  

SciTech Connect

Numerous neutron scattering studies of bio-molecular dynamics employ a qualitative analysis of elastic scattering data and atomic mean square displacements. We provide a new quantitative approach showing that the intensity at zero energy exchange can be a rich source of information of bio-structural fluctuations on a pico- to nano-second time scale. Elastic intensity scans performed either as a function of the temperature (back-scattering) and/or by varying the instrumental resolution (time of flight spectroscopy) yield the activation parameters of molecular motions and the approximate structural correlation function in the time domain. The two methods are unified by a scaling function, which depends on the ratio of correlation time and instrumental resolution time. The elastic scattering concept is illustrated with a dynamic characterization of alanine-dipeptide, protein hydration water, and water-coupled protein motions of lysozyme, per-deuterated c-phycocyanin (CPC) and hydrated myoglobin. The complete elastic scattering function versus temperature, momentum exchange, and instrumental resolution is analyzed instead of focusing on a single cross-over temperature of mean square displacements at the apparent onset temperature of an-harmonic motions. Our method predicts the protein dynamical transition (PDT) at T{sub d} from the collective (?) structural relaxation rates of the solvation shell as input. By contrast, the secondary (?) relaxation enhances the amplitude of fast local motions in the vicinity of the glass temperature T{sub g}. The PDT is specified by step function in the elastic intensity leading from elastic to viscoelastic dynamic behavior at a transition temperature T{sub d}.

Doster, W. [Physik-Department, Technische Universität München, D-85748 Garching (Germany)] [Physik-Department, Technische Universität München, D-85748 Garching (Germany); Nakagawa, H. [Jülich Centre for Neutron Science, Forschungszentrum Jülich GmbH, Outstation at MLZ, Lichtenbergstraße 1, 85747 Garching (Germany) [Jülich Centre for Neutron Science, Forschungszentrum Jülich GmbH, Outstation at MLZ, Lichtenbergstraße 1, 85747 Garching (Germany); Japan Atomic Energy Agency, Quantum Beam Science Directorate, Tokai, Ibaraki 319-1195 (Japan); Appavou, M. S. [Jülich Centre for Neutron Science, Forschungszentrum Jülich GmbH, Outstation at MLZ, Lichtenbergstraße 1, 85747 Garching (Germany)] [Jülich Centre for Neutron Science, Forschungszentrum Jülich GmbH, Outstation at MLZ, Lichtenbergstraße 1, 85747 Garching (Germany)

2013-07-28T23:59:59.000Z

283

Classical spin model of the relaxation dynamics of rare-earth doped permalloy  

Science Journals Connector (OSTI)

In this paper, the ultrafast dynamic behavior of rare-earth doped permalloy is investigated using an atomistic spin model with Langevin dynamics. In line with experimental work, the effective Gilbert damping is calculated from transverse relaxation simulations, which shows that rare-earth doping causes an increase in the damping. Analytic theory suggests that this increase in damping would lead to a decrease in the demagnetization time. However, longitudinal relaxation calculations show an increase with doping concentration instead. The simulations are in a good agreement with previous experimental work of Radu et al. [Radu et al., Phys. Rev. Lett. 102, 117201 (2009)]. The longitudinal relaxation time of the magnetization is shown to be driven by the interaction between the transition metal and the laser-excited conduction electrons, whereas the effective damping is predominantly determined by the slower interaction between the rare-earth elements and the phonon heat bath. We conclude that for complex materials, it is evidently important not to expect a single damping parameter but to consider the energy transfer channel relevant to the technique and time scale of the measurement.

M. O. A. Ellis; T. A. Ostler; R. W. Chantrell

2012-11-19T23:59:59.000Z

284

Theoretical and experimental study of dynamics of photoexcited carriers in GaN  

SciTech Connect

We present a theoretical and experimental study of the sub-picosecond dynamics of photo-excited carriers in GaN. In the theoretical model, interaction with an external ultrafast laser pulse is treated coherently and to account for the scattering mechanisms and dephasing processes, a generalized Monte-Carlo simulation is used. The scattering mechanisms included are carrier interactions with polar optical phonons and acoustic phonons, and carrier-carrier Coulomb interactions. We study the effect of different scattering mechanisms on the carrier densities. In the case that the excitation energy satisfies the threshold for polar optical scattering, phonon contribution is the dominant process in relaxing the system, otherwise, carrier-carrier mechanism is dominant. Furthermore, we present the temperature and pulse power dependent normalized luminescence intensity. The results are presented over a range of temperatures, electric field, and excitation energy of the laser pulse. For comparison, we also report the experimental time-resolved photoluminescence studies on GaN samples. There is a good agreement between the simulation and experiment in normalized luminescence intensity results. Therefore, we show that we can explain the dynamics of the photo-excited carriers in GaN by including only carrier-carrier and carrier-phonon interactions and a relatively simple two-band electronic structure model.

Shishehchi, Sara; Bellotti, Enrico, E-mail: bellotti@bu.edu [ECE Department, Boston University, 8 Saint Mary's Street, Boston, Massachusetts 02215 (United States); Rudin, Sergey; Garrett, Gregory A.; Wraback, Michael [Sensors and Electron Devices Directorate, US Army Research Laboratory, 2800 Powder Mill Rd, Adelphi, Maryland 20783 (United States)

2013-12-21T23:59:59.000Z

285

Substrate-induced microstructure effects on the dynamics of the photo-induced Metal-insulator transition in VO$_2$ thin films  

E-Print Network (OSTI)

We investigate the differences in the dynamics of the ultrafast photo-induced metal-insulator transition (MIT) of two VO$_2$ thin films deposited on different substrates, TiO$_2$ and Al$_2$O$_3$, and in particular the temperature dependence of the threshold laser fluence values required to induce various MIT stages in a wide range of sample temperatures (150 K - 320 K). We identified that, although the general pattern of MIT evolution was similar for the two samples, there were several differences. Most notably, the threshold values of laser fluence required to reach the transition to a fully metallic phase in the VO$_2$ film on the TiO$_2$ substrate were nearly constant in the range of temperatures considered, whereas the VO$_2$/Al$_2$O$_3$ sample showed clear temperature dependence. Our analysis qualitatively connects such behavior to the structural differences in the two VO$_2$ films.

Radue, E; Kittiwatanakul, S; Lu, J; Wolf, S A; Rossi, E; Lukaszew, R A; Novikova, I

2014-01-01T23:59:59.000Z

286

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

SciTech Connect

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){sub n} and (EC){sup ?}{sub n} clusters devoid of Li{sub +} ions, n?=?1–6, 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 carbon–oxygen covalent bond compared to EC{sub ?}. In ab initio molecular dynamics (AIMD) simulations of EC{sub ?} solvated in liquid EC, large fluctuations in the carbonyl carbon–oxygen 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.

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

2011-01-01T23:59:59.000Z

287

Computing the Free Energy along a Reaction Coordinate Using Rigid Body Dynamics  

Science Journals Connector (OSTI)

Since SM8 was parametrized against experimental aqueous solvation free energies, the correlation between our FEG-RBD results and SM8 results along the reaction pathway, at least in steps II and III, strongly suggests that our FEG-RBD method captures the nonpolarizable portion of solvation free energy, especially the contribution from cavitation, dispersion, and solvent structural effects. ... mechanics (QM/MM) methods provide an accurate and efficient energetic description of complex chem. ...

Peng Tao; Alexander J. Sodt; Yihan Shao; Gerhard König; Bernard R. Brooks

2014-08-15T23:59:59.000Z

288

All-Atom Empirical Potential for Molecular Modeling and Dynamics Studies of Proteins A. D. MacKerell, Jr.,*,, D. Bashford,, M. Bellott,, R. L. Dunbrack, Jr.,, J. D. Evanseck,,  

E-Print Network (OSTI)

*,,| Department of Chemistry & Chemical Biology, HarVard UniVersity, Cambridge, Massachusetts 02138, Department, dipole moments, experimental heats and free energies of vaporization, solvation and sublimation

Straub, John E.

289

Essays in dynamic contracting  

E-Print Network (OSTI)

This thesis examines three models of dynamic contracting. The first model is a model of dynamic moral hazard with partially persistent states, and the second model considers relational contracts when the states are partially ...

Kwon, Suehyun

2012-01-01T23:59:59.000Z

290

Time-Dependent Stokes Shift and Its Calculation from Solvent Dielectric Dispersion Data Chao-Ping Hsu, Xueyu Song, and R. A. Marcus*  

E-Print Network (OSTI)

are barely changed. In those cases, instead of vibrational Franck-Condon factors or of frictional effects due. Recent theoretical developments9-20 have provided physical insight into the solvation dynamics. Solvation(t), the solvation correlation function.8 The effect of molecular shape has also been discussed.10 Much attention has

Song, Xueyu

291

Intramolecular and nonlinear dynamics  

SciTech Connect

Research in this program focuses on three interconnected areas. The first involves the study of intramolecular dynamics, particularly of highly excited systems. The second area involves the use of nonlinear dynamics as a tool for the study of molecular dynamics and complex kinetics. The third area is the study of the classical/quantum correspondence for highly excited systems, particularly systems exhibiting classical chaos.

Davis, M.J. [Argonne National Laboratory, IL (United States)

1993-12-01T23:59:59.000Z

292

Influence of Domain Wall Pinning on the Dynamic Behavior of Magnetic  

NLE Websites -- All DOE Office Websites (Extended Search)

Influence of Domain Wall Pinning on the Dynamic Behavior of Magnetic Vortices Print 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 by a small alternating magnetic field, it could serve as a memory bit in future magnetic memory devices. However, these magnetic structures often contain numerous imperfections such as domain wall pinning sites, which have to be taken into account for the practical application of such systems. To study how these defects affect the dynamics of magnetic vortices, researchers from Belgium, Germany, and the United States investigated square-shaped and disk-shaped thin-film structures with artificially introduced imperfections in the form of nanometer-sized holes. They used time-resolved scanning transmission x-ray microscopy (STXM) at ALS Beamline 11.0.2 to determine the frequency at which these vortices vibrate (their eigenfrequency). The imperfections were found to cause a higher vibrational frequency in square-shaped structures, but did not influence the disk-shaped structures. Knowledge of the frequency is crucial for vortex-based memories, since the electric signal for writing data needs to be precisely tuned to it.

293

Influence of Domain Wall Pinning on the Dynamic Behavior of Magnetic  

NLE Websites -- All DOE Office Websites (Extended Search)

Influence of Domain Wall Pinning on the Dynamic Behavior of Magnetic Vortices Print 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 by a small alternating magnetic field, it could serve as a memory bit in future magnetic memory devices. However, these magnetic structures often contain numerous imperfections such as domain wall pinning sites, which have to be taken into account for the practical application of such systems. To study how these defects affect the dynamics of magnetic vortices, researchers from Belgium, Germany, and the United States investigated square-shaped and disk-shaped thin-film structures with artificially introduced imperfections in the form of nanometer-sized holes. They used time-resolved scanning transmission x-ray microscopy (STXM) at ALS Beamline 11.0.2 to determine the frequency at which these vortices vibrate (their eigenfrequency). The imperfections were found to cause a higher vibrational frequency in square-shaped structures, but did not influence the disk-shaped structures. Knowledge of the frequency is crucial for vortex-based memories, since the electric signal for writing data needs to be precisely tuned to it.

294

Influence of Domain Wall Pinning on the Dynamic Behavior of Magnetic  

NLE Websites -- All DOE Office Websites (Extended Search)

Influence of Domain Wall Pinning on the Dynamic Behavior of Magnetic Vortices Print 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 by a small alternating magnetic field, it could serve as a memory bit in future magnetic memory devices. However, these magnetic structures often contain numerous imperfections such as domain wall pinning sites, which have to be taken into account for the practical application of such systems. To study how these defects affect the dynamics of magnetic vortices, researchers from Belgium, Germany, and the United States investigated square-shaped and disk-shaped thin-film structures with artificially introduced imperfections in the form of nanometer-sized holes. They used time-resolved scanning transmission x-ray microscopy (STXM) at ALS Beamline 11.0.2 to determine the frequency at which these vortices vibrate (their eigenfrequency). The imperfections were found to cause a higher vibrational frequency in square-shaped structures, but did not influence the disk-shaped structures. Knowledge of the frequency is crucial for vortex-based memories, since the electric signal for writing data needs to be precisely tuned to it.

295

Influence of Domain Wall Pinning on the Dynamic Behavior of Magnetic  

NLE Websites -- All DOE Office Websites (Extended Search)

Influence of Domain Wall Pinning on the Dynamic Behavior of Magnetic Vortices Print 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 by a small alternating magnetic field, it could serve as a memory bit in future magnetic memory devices. However, these magnetic structures often contain numerous imperfections such as domain wall pinning sites, which have to be taken into account for the practical application of such systems. To study how these defects affect the dynamics of magnetic vortices, researchers from Belgium, Germany, and the United States investigated square-shaped and disk-shaped thin-film structures with artificially introduced imperfections in the form of nanometer-sized holes. They used time-resolved scanning transmission x-ray microscopy (STXM) at ALS Beamline 11.0.2 to determine the frequency at which these vortices vibrate (their eigenfrequency). The imperfections were found to cause a higher vibrational frequency in square-shaped structures, but did not influence the disk-shaped structures. Knowledge of the frequency is crucial for vortex-based memories, since the electric signal for writing data needs to be precisely tuned to it.

296

Carrier capture dynamics of single InGaAs/GaAs quantum-dot layers  

SciTech Connect

Using 800 nm, 25-fs pulses from a mode locked Ti:Al{sub 2}O{sub 3} laser, we have measured the ultrafast optical reflectivity of MBE-grown, single-layer In{sub 0.4}Ga{sub 0.6}As/GaAs quantum-dot (QD) samples. The QDs are formed via two-stage Stranski-Krastanov growth: following initial InGaAs deposition at a relatively low temperature, self assembly of the QDs occurs during a subsequent higher temperature anneal. The capture times for free carriers excited in the surrounding GaAs (barrier layer) are as short as 140 fs, indicating capture efficiencies for the InGaAs quantum layer approaching 1. The capture rates are positively correlated with initial InGaAs thickness and annealing temperature. With increasing excited carrier density, the capture rate decreases; this slowing of the dynamics is attributed to Pauli state blocking within the InGaAs quantum layer.

Chauhan, K. N.; Riffe, D. M.; Everett, E. A.; Kim, D. J.; Yang, H. [Physics Department, Utah State University, Logan, Utah 84322-4415 (United States)] [Physics Department, Utah State University, Logan, Utah 84322-4415 (United States); Shen, F. K. [Center for Surface Analysis and Applications, Utah State University, Logan, Utah 84322-4415 (United States)] [Center for Surface Analysis and Applications, Utah State University, Logan, Utah 84322-4415 (United States)

2013-05-28T23:59:59.000Z

297

Dynamically controlling the emission of single excitons in photonic crystal cavities  

E-Print Network (OSTI)

Single excitons in semiconductor microcavities represent a solid-state and scalable platform for cavity quantum electrodynamics (c-QED), potentially enabling an interface between flying (photon) and static (exciton) quantum bits in future quantum networks. While both single-photon emission and the strong coupling regime have been demonstrated, further progress has been hampered by the inability to control the coherent evolution of the c-QED system in real time, as needed to produce and harness charge-photon entanglement. Here, using the ultrafast electrical tuning of the exciton energy in a photonic crystal (PhC) diode, we demonstrate the dynamic control of the coupling of a single exciton to a PhC cavity mode on a sub-ns timescale, faster than the natural lifetime of the exciton, for the first time. This opens the way to the control of single-photon waveforms, as needed for quantum interfaces, and to the real-time control of solid-state c-QED systems.

Francesco Pagliano; YongJin Cho; Tian Xia; Frank van Otten; Robert Johne; Andrea Fiore

2014-11-03T23:59:59.000Z

298

Dynamically controlling the emission of single excitons in photonic crystal cavities  

E-Print Network (OSTI)

Single excitons in semiconductor microcavities represent a solid-state and scalable platform for cavity quantum electrodynamics (c-QED), potentially enabling an interface between flying (photon) and static (exciton) quantum bits in future quantum networks. While both single-photon emission and the strong coupling regime have been demonstrated, further progress has been hampered by the inability to control the coherent evolution of the c-QED system in real time, as needed to produce and harness charge-photon entanglement. Here, using the ultrafast electrical tuning of the exciton energy in a photonic crystal (PhC) diode, we demonstrate the dynamic control of the coupling of a single exciton to a PhC cavity mode on a sub-ns timescale, faster than the natural lifetime of the exciton, for the first time. This opens the way to the control of single-photon waveforms, as needed for quantum interfaces, and to the real-time control of solid-state c-QED systems.

Pagliano, Francesco; Xia, Tian; van Otten, Frank; Johne, Robert; Fiore, Andrea

2014-01-01T23:59:59.000Z

299

3 - Mobile Robot Dynamics  

Science Journals Connector (OSTI)

Mobile robot dynamics is a challenging field on its own, especially due to the variety of the imposed constraints. Delicate stability and control problems that have very often to be faced are due to longitudinal or lateral slip, and to the features of the ground (roughness, etc.). This chapter has the following objectives: (i) to present the general dynamic modeling concepts and techniques of robots, (ii) to study the Newton–Euler and Lagrange dynamic models of differential-drive mobile robots, (iii) to study the dynamics of differential-drive mobile robots with longitudinal and lateral slip, (iv) to derive a dynamic model of car-like wheeled mobile robots, (v) to derive a dynamic model of three-wheel omnidirectional robots, and (vi) to derive a dynamic model of four-wheel mecanum omnidirectional robots.

Spyros G. Tzafestas

2014-01-01T23:59:59.000Z

300

AVESTAR® - Dynamic Modeling  

NLE Websites -- All DOE Office Websites (Extended Search)

Dynamic Modeling Dynamic Modeling The AVESTAR team is pursuing research on the dynamic modeling and simulation of advanced energy systems ranging from power plants to power grids. Dynamic models provide a continuous view of energy systems in action by calculating their transient behavior over time. Plant-wide Models For power plants, dynamic models are used to analyze a wide variety of operating scenarios, including normal base load operation, startup, shutdown, feedstock switchovers, cycling, and load-following. Dynamic process and control models are also essential for analyzing plant responses to setpoint changes and disturbances, as well as malfunctions and abnormal situations. Other applications of plant-wide dynamic models include controllability and operational flexibility analyses, environmental studies, safety evaluations, and risk mitigation.

Note: This page contains sample records for the topic "ultrafast solvation dynamics" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


301

Dynamical friction in modified Newtonian dynamics  

E-Print Network (OSTI)

We have tested a previous analytical estimate of the dynamical friction timescale in Modified Newtonian Dynamics (MOND) with fully non-linear N-body simulations. The simulations confirm that the dynamical friction timescale is significantly shorter in MOND than in equivalent Newtonian systems, i.e. systems with the same phase-space distribution of baryons and additional dark matter. An apparent conflict between this result and the long timescales determined for bars to slow and mergers to be completed in previous N-body simulations of MOND systems is explained. The confirmation of the short dynamical-friction timescale in MOND underlines the challenge that the Fornax dwarf spheroidal poses to the viability of MOND.

C. Nipoti; L. Ciotti; J. Binney; P. Londrillo

2008-02-08T23:59:59.000Z

302

Chemical Structure and Dynamics  

NLE Websites -- All DOE Office Websites (Extended Search)

2154-3 2154-3 UC-400 Annual Report 2000 Chemical Structure and Dynamics Steven D. Colson, Associate Director Robin S. McDowell, Program Manager and the Staff of the Chemical Structure and Dynamics Program April 2001 Prepared for the U.S. Department of Energy under Contract DE-AC06-76RL01830 Chemical Structure and Dynamics 2000 Annual Report Contents Chemical Structure and Dynamics 2000 Annual Report Chemical Structure and Dynamics 2000 Annual Report 1. Introduction Chemical Structure and Dynamics Program......................................................... 1-3 2. Reaction Mechanisms at Liquid Interfaces Structure and Reactivity of Ice Surfaces and Interfaces G. A. Kimmel, Z. Dohnálek, K. P. Stevenson, R. S. Smith,

303

Dynamic Instruction Fusion  

E-Print Network (OSTI)

SANTA CRUZ DYNAMIC INSTRUCTION FUSION A thesis submitted in4 2.2 Instruction Fusion & Complex10 3.1 Fusion Selection

Lee, Ian

2012-01-01T23:59:59.000Z

304

Accelerated Molecular Dynamics Methods  

Energy.gov (U.S. Department of Energy (DOE))

This presentation on Accelerated Molecular Dynamics Methods was given at the DOE Theory Focus Session on Hydrogen Storage Materials on May 18, 2006.

305

Seminar N 03301, Dynamically  

E-Print Network (OSTI)

Seminar Nº 03301, Dynamically Reconfigurable Architectures A Mead-&-Conway-like Break ·Ametek ·Applied Dynamics ·Astronautics ·BBN ·CDC ·Convex ·Cray Computer ·Cray Research ·Culler-Harris

Hartenstein, Reiner

306

Photosynthesis in Dynamic Animations  

Science Journals Connector (OSTI)

Photosynthesis in Dynamic Animations ... To support chemistry instruction in high school we created a series of interactive animations that show photosynthetic processes in a eukaryotic cell. ... The example from the educational program “Photosynthesis in Dynamic Animations”, the description of photosynthetic cell. ...

Milada Teplá; Helena Klímová

2013-10-09T23:59:59.000Z

307

Ultra-fast laser system  

DOE Patents (OSTI)

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.

Dantus, Marcos; Lozovoy, Vadim V

2014-01-21T23:59:59.000Z

308

Ultrafast Transformations in Superionic Nanocrystals  

NLE Websites -- All DOE Office Websites (Extended Search)

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...

309

Ultrafast Transformations in Superionic Nanocrystals  

NLE Websites -- All DOE Office Websites (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...

310

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...

311

Beam Dynamics for Induction Accelerators  

E-Print Network (OSTI)

Dynamics for Induction Accelerators Edward P. Lee Lawrencea natural candidate accelerator for a heavy ion fusion (HIF)words: Fusion, Induction, Accelerators, Dynamics This work

Lee, E.P.

2014-01-01T23:59:59.000Z

312

mark | The Ames Laboratory  

NLE Websites -- All DOE Office Websites (Extended Search)

and on surfaces New methods for treating the effects of solvation, for interfacing electronic structure calculations with dynamics, for obtaining accurate wave functions and...

313

Towards a Hybrid Dynamic Logic for Hybrid Dynamic Systems1  

E-Print Network (OSTI)

HyLo 2006 Towards a Hybrid Dynamic Logic for Hybrid Dynamic Systems1 Andr´e Platzer2 Carnegie platzer@informatik.uni-oldenburg.de Abstract We introduce a hybrid variant of a dynamic logic for this extended hybrid dynamic logic. With the addition of satisfaction operators, this hybrid logic provides

Platzer, André

314

Fundamentals of Dynamical Systems  

Science Journals Connector (OSTI)

For the purposes of control system design, analysis, test, and repair, the most important part of the very broad subject known as system theory is the theory of dynamical systems. It is difficult to give a pre...

William S. Levine

2005-01-01T23:59:59.000Z

315

Swarms in dynamic environments  

Science Journals Connector (OSTI)

Charged particle swarm optimization (CPSO) is well suited to the dynamic search problem since inter-particle repulsion maintains population diversity and good tracking can be achieved with a simple algorithm. This work extends the application of CPSO ...

T. M. Blackwell

2003-07-01T23:59:59.000Z

316

Biological Interactions and Dynamics  

NLE Websites -- All DOE Office Websites (Extended Search)

PNNL-20717 Biological Interactions and Dynamics Science Theme Advisory Panel (BID-STAP) May 2011 Report: September 2011 Prepared for the U.S. Department of Energy's Office of...

317

Testing dynamically reconfigurable FPGAs  

E-Print Network (OSTI)

In this work, testing methods are proposed to test the ics. logic resources and the interconnect structure of dynamically reconfigurable FPGAS. Testing methods are also proposed for testing the dedicated CPU interface in these FPGAS. A BIST...

Ruiwale, Sameer Jagadish

2012-06-07T23:59:59.000Z

318

Accelerating dynamic programming  

E-Print Network (OSTI)

Dynamic Programming (DP) is a fundamental problem-solving technique that has been widely used for solving a broad range of search and optimization problems. While DP can be invoked when more specialized methods fail, this ...

Weimann, Oren

2009-01-01T23:59:59.000Z

319

Dynamic Instruction Fusion  

E-Print Network (OSTI)

File Size Dynamic Read Energy (nJ) # of Ports Figure 17:with fewer ports, are much less expensive energy-wise. By “Energy by Register File Size Leakage Power (mW) # of Ports

Lee, Ian

2012-01-01T23:59:59.000Z

320

Multipulsed dynamic moire interferometer  

DOE Patents (OSTI)

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.

Deason, Vance A. (Idaho Falls, ID)

1991-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "ultrafast solvation dynamics" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


321

Photochemical reaction dynamics  

SciTech Connect

The purpose of the program is to develop a fundamental understanding of unimolecular and bimolecular reaction dynamics with application in combustion and energy systems. The energy dependence in ketene isomerization, ketene dissociation dynamics, and carbonyl substitution on organometallic rhodium complexes in liquid xenon have been studied. Future studies concerning unimolecular processes in ketene as well as energy transfer and kinetic studies of methylene radicals are discussed.

Moore, B.C. [Lawrence Berkeley Laboratory, Livermore, CA (United States)

1993-12-01T23:59:59.000Z

322

Local Writhing Dynamics  

E-Print Network (OSTI)

We present an alternative local definition of the writhe of a self-avoiding closed loop which differs from the traditional non-local definition by an integer. When studying dynamics this difference is immaterial. We employ a formula due to Aldinger, Klapper and Tabor for the change in writhe and propose a set of local, link preserving dynamics in an attempt to unravel some puzzles about actin.

Randall D. Kamien

1997-03-13T23:59:59.000Z

323

Time-resolved THz studies of carrier dynamics in semiconductors, superconductors, and strongly-correlated electron materials  

SciTech Connect

Perhaps the most important aspect of contemporary condensed matter physics involves understanding strong Coulomb interactions between the large number of electrons in a solid. Electronic correlations lead to the emergence of new system properties, such as metal-insulator transitions, superconductivity, magneto-resistance, Bose-Einstein condensation, the formation of excitonic gases, or the integer and fractional Quantum Hall effects. The discovery of high-Tc superconductivity in particular was a watershed event, leading to dramatic experimental and theoretical advances in the field of correlated-electron systems. Such materials often exhibit competition between the charge, lattice, spin, and orbital degrees of freedom, whose cause-effect relationships are difficult to ascertain. Experimental insight into the properties of solids is traditionally obtained by time-averaged probes, which measure e.g., linear optical spectra, electrical conduction properties, or the occupied band structure in thermal equilibrium. Many novel physical properties arise from excitations out of the ground state into energetically higher states by thermal, optical, or electrical means. This leads to fundamental interactions between the system's constituents, such as electron-phonon and electron-electron interactions, which occur on ultrafast timescales. While these interactions underlie the physical properties of solids, they are often only indirectly inferred from time-averaged measurements. Time-resolved spectroscopy, consequently, is playing an ever increasing role to provide insight into light-matter interaction, microscopic processes, or cause-effect relationships that determine the physics of complex materials. In the past, experiments using visible and near-infrared femtosecond pulses have been extensively employed, e.g. to follow relaxation and dephasing processes in metals and semiconductors. However, many basic excitations in strongly-correlated electron systems and nanoscale materials occur at lower energies. The terahertz (THz) regime is particularly rich in such fundamental resonances. This includes ubiquitous lattice vibrations and low-energy collective oscillations of conduction charges. In nanoscale materials, band structure quantization also yields novel infrared and THz transitions, including intersubband absorption in quantum wells. The formation of excitons in turn leads to low-energy excitations analogous to inter-level transitions in atoms. In transition-metal oxides, fundamental excitation gaps arise from charge pairing into superconducting condensates and other correlated states. This motivates the use of ultrafast THz spectroscopy as a powerful tool to study light-matter interactions and microscopic processes in nanoscale and correlated-electron materials.A distinct advantage of coherent THz pulses is that the amplitude and phase of the electric field can be measured directly, as the THz fields are coherent with the fs pulses from which they are generated. Using THz time-domain spectroscopy (THz-TDS), both the real and imaginary parts of the response functions (such as the dielectric function) are obtained directly without the need for Kramers?Kronig transforms. The THz response can also be expressed in terms of absorption and refractive index, or as the optical conductivity. The optical conductivity describes the current response of a many-body system to an electric field, an ideal tool to study conducting systems. A second important advantage is the ultrafast time resolution that results from the short temporal duration of the THz time-domain sources. In particular, optical-pump THz-probe spectroscopy enables a delicate probe of the transient THz conductivity after optical photoexcitation. These experiments can provide insight into quasiparticle interactions, phase transitions, or nonequilibrium dynamics. In this chapter we will provide many such examples. Since THz spectroscopy of solids is a quickly expanding field

Kaindl, Robert A.; Averitt, Richard D.

2006-11-14T23:59:59.000Z

324

Surface Chemical Dynamics  

NLE Websites -- All DOE Office Websites (Extended Search)

Surface Chemical Dynamics Surface Chemical Dynamics The goal of the Surface Chemical Dynamics Program is to elucidate the underlying physical processes that determine the products (selectivity) and yield (efficiency) of chemical transformations relevant to energy-related chemistry on catalytic and nanostructured surfaces. Achieving this end requires understanding the evolution of the reactant-molecule/surface complex as molecules adsorb, bonds dissociate, surface species diffuse, new bonds form and products desorb. The pathways and time scales of these processes are ultimately determined by a multidimensional potential energy surface that is a function of the geometric and electronic structures of the surface and the reactant, product, intermediate and transition-state molecular and atomic species.

325

MAX Fluid Dynamics facility  

NLE Websites -- All DOE Office Websites (Extended Search)

MAX Fluid Dynamics facility MAX Fluid Dynamics facility Capabilities Engineering Experimentation Reactor Safety Testing and Analysis Overview Nuclear Reactor Severe Accident Experiments MAX NSTF SNAKE Aerosol Experiments System Components Laser Applications Robots Applications Other Facilities Other Capabilities Work with Argonne Contact us For Employees Site Map Help Join us on Facebook Follow us on Twitter NE on Flickr MAX Fluid Dynamics facility Providing high resolution data for development of computational tools that model fluid flow and heat transfer within complex systems such as the core of a nuclear reactor. 1 2 3 4 5 Hot and cold air jets are mixed within a glass tank while laser-based anemometers and a high-speed infrared camera characterize fluid flow and heat transfer behavior. Click on image to view larger size image.

326

Li(Mn1/3Ni1/3Fe1/3)O2–Polyaniline hybrids as cathode active material with ultra-fast charge–discharge capability for lithium batteries  

Science Journals Connector (OSTI)

We first report the ultra-fast charge–discharge capability of organic–inorganic (Li(Mn1/3Ni1/3Fe1/3)O2–Polyaniline (PANI)) nanocomposites prepared by mixed hydroxide route and followed by polymerization of aniline monomers with different concentrations (0.1 and 0.2 mol concentration of PANI). Li-insertion properties are evaluated in half-cell configuration, test cell (Li/Li(Mn1/3Ni1/3Fe1/3)O2–PANI) comprising 0.2 mol. PANI delivered the reversible capacity of ?127, ?114 and ?110 mAh g?1 at ultra-high current rate of 5, 30 and 40 C, respectively with exceptional cycleability between 2 and 4.5 V vs. Li. Such an exceptional performance is mainly due to the conducting pathways promoted by PANI network and it is revealed by impedance measurements. This result certainly provides the possibility of using such layered type Fe based cathode materials in high power Li-ion batteries to drive zero emission vehicles such as hybrid electric vehicles or electric vehicles applications in near future.

K. Karthikeyan; S. Amaresh; V. Aravindan; W.S. Kim; K.W. Nam; X.Q. Yang; Y.S. Lee

2013-01-01T23:59:59.000Z

327

View dependent fluid dynamics  

E-Print Network (OSTI)

VIEW DEPENDENT FLUID DYNAMICS A Thesis by BRIAN ARTHUR BARRAN Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE May 2006 Major Subject: Visualization... Sciences VIEW DEPENDENT FLUID DYNAMICS A Thesis by BRIAN ARTHUR BARRAN Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Approved by: Chair of Committee, Donald...

Barran, Brian Arthur

2006-08-16T23:59:59.000Z

328

Dissipative Dynamics of Enzymes  

Science Journals Connector (OSTI)

We explore enzyme conformational dynamics at sub-Å resolution, specifically, temperature effects. The ensemble-averaged mechanical response of the folded enzyme is viscoelastic in the whole temperature range between the warm and cold denaturation transitions. The dissipation parameter ? of the viscoelastic description decreases by a factor of 2 as the temperature is raised from 10 to 45?°C; the elastic parameter K shows a similar decrease. Thus, when probed dynamically, the enzyme softens for increasing temperature. Equilibrium mechanical experiments with the DNA spring (and a different enzyme) also show, qualitatively, a small softening for increasing temperature.

Amila Ariyaratne; Chenhao Wu; Chiao-Yu Tseng; Giovanni Zocchi

2014-11-04T23:59:59.000Z

329

Quantum spin dynamics  

E-Print Network (OSTI)

The classical Landau-Lifshitz equation has been derived from quantum mechanics. Starting point is the assumption of a non-Hermitian Hamilton operator to take the energy dissipation into account. The corresponding quantum mechanical time dependent Schr\\"odinger, Liouville and Heisenberg equation have been described and the similarities and differences between classical and quantum mechanical spin dynamics have been discussed. Furthermore, a time dependent Schr\\"odinger equation corresponding to the classical Landau-Lifshitz-Gilbert equation and two ways to include temperature into the quantum mechanical spin dynamics have been proposed.

Robert Wieser

2014-10-23T23:59:59.000Z

330

Electronic Spectroscopy & Dynamics  

SciTech Connect

The Gordon Research Conference (GRC) on Electronic Spectroscopy and Dynamics was held at Colby College, Waterville, NH from 07/19/2009 thru 07/24/2009. The Conference was well-attended with participants (attendees list attached). The attendees represented the spectrum of endeavor in this field coming from academia, industry, and government laboratories, both U.S. and foreign scientists, senior researchers, young investigators, and students. The GRC on Electronic Spectroscopy & Dynamics showcases some of the most recent experimental and theoretical developments in electronic spectroscopy that probes the structure and dynamics of isolated molecules, molecules embedded in clusters and condensed phases, and bulk materials. Electronic spectroscopy is an important tool in many fields of research, and this GRC brings together experts having diverse backgrounds in physics, chemistry, biophysics, and materials science, making the meeting an excellent opportunity for the interdisciplinary exchange of ideas and techniques. Topics covered in this GRC include high-resolution spectroscopy, biological molecules in the gas phase, electronic structure theory for excited states, multi-chromophore and single-molecule spectroscopies, and excited state dynamics in chemical and biological systems.

Mark Maroncelli, Nancy Ryan Gray

2010-06-08T23:59:59.000Z

331

Dynamic Modelling, Measurement and  

E-Print Network (OSTI)

Dynamic Modelling, Measurement and Control of Co-rotating Twin-Screw Extruders Justin Rae Elsey, B;Summary Co-rotating twin-screw extruders are unique and versatile machines that are used widely that these extruders are currently being optimally utilised. The most signi cant improvement to the eld of twin-screw

Fernandez, Thomas

332

NEWS & VIEWS Glass dynamics  

E-Print Network (OSTI)

NEWS & VIEWS Glass dynamics Diverging views on glass transition Gregory B. mc.mckenna@ttu.edu T he glass transition is one of the most intriguing phenomena in the world of soft condensed matter. Despite decades of study, many aspects of the behaviour of glass-forming liquids remain elusive

Weeks, Eric R.

333

Interaction and dynamics of (alkylamide + electrolyte) deep eutectics: Dependence on alkyl chain-length, temperature, and anion identity  

SciTech Connect

Here we investigate the solute-medium interaction and solute-centered dynamics in (RCONH{sub 2} + LiX) deep eutectics (DEs) via carrying out time-resolved fluorescence measurements and all-atom molecular dynamics simulations at various temperatures. Alkylamides (RCONH{sub 2}) considered are acetamide (CH{sub 3}CONH{sub 2}), propionamide (CH{sub 3}CH{sub 2}CONH{sub 2}), and butyramide (CH{sub 3}CH{sub 2}CH{sub 2}CONH{sub 2}); the electrolytes (LiX) are lithium perchlorate (LiClO{sub 4}), lithium bromide (LiBr), and lithium nitrate (LiNO{sub 3}). Differential scanning calorimetric measurements reveal glass transition temperatures (T{sub g}) of these DEs are ?195 K and show a very weak dependence on alkyl chain-length and electrolyte identity. Time-resolved and steady state fluorescence measurements with these DEs have been carried out at six-to-nine different temperatures that are ?100–150 K above their individual T{sub g}s. Four different solute probes providing a good spread of fluorescence lifetimes have been employed in steady state measurements, revealing strong excitation wavelength dependence of probe fluorescence emission peak frequencies. Extent of this dependence, which shows sensitivity to anion identity, has been found to increase with increase of amide chain-length and decrease of probe lifetime. Time-resolved measurements reveal strong fractional power dependence of average rates for solute solvation and rotation with fraction power being relatively smaller (stronger viscosity decoupling) for DEs containing longer amide and larger (weaker decoupling) for DEs containing perchlorate anion. Representative all-atom molecular dynamics simulations of (CH{sub 3}CONH{sub 2} + LiX) DEs at different temperatures reveal strongly stretched exponential relaxation of wavevector dependent acetamide self dynamic structure factor with time constants dependent both on ion identity and temperature, providing justification for explaining the fluorescence results in terms of temporal heterogeneity and amide clustering in these multi-component melts.

Guchhait, Biswajit; Das, Suman; Daschakraborty, Snehasis; Biswas, Ranjit, E-mail: ranjit@bose.res.in [Department of Chemical, Biological and Macromolecular Sciences, S. N. Bose National Centre for Basic Sciences, Block-JD, Sector-III, Salt Lake, Kolkata 700098 (India)] [Department of Chemical, Biological and Macromolecular Sciences, S. N. Bose National Centre for Basic Sciences, Block-JD, Sector-III, Salt Lake, Kolkata 700098 (India)

2014-03-14T23:59:59.000Z

334

Electron dynamics in chromium probed with 20-fs optical pulses  

Science Journals Connector (OSTI)

Electron excitation and relaxation in chromium are probed with 20-fs time resolution using an ultrafast optical technique. We obtain good fits to the data for the transient reflectivity and transmittivity changes in a thin film using a simple model of electron relaxation, suggesting the existence of an efficient electron-electron thermalization process on ultrashort-time scales. Quantitative analysis allows the extraction of thermo-optic coefficients and dielectric constant variations related to both the electron and the lattice temperatures.

H. Hirori; T. Tachizaki; O. Matsuda; O. B. Wright

2003-09-16T23:59:59.000Z

335

Dynamics of acyclic interval maps  

E-Print Network (OSTI)

Vol. 6 (2009) Dynamics of acyclic interval maps [16] D.orbits and bifurcation of maps of the interval. SIAM J.Dynamics of acyclic interval maps Morris W. Hirsch He who

Hirsch, Morris W

2009-01-01T23:59:59.000Z

336

Models of Dynamical Supersymmetry Breaking  

E-Print Network (OSTI)

We review a class of models of dynamical supersymmetry breaking, and give a unified description of these models.

Lisa Randall

1997-06-23T23:59:59.000Z

337

(Clusters: Elucidating the dynamics of ionization events and ensuing reactions in the condensed phase)  

SciTech Connect

New insight into a variety of phenomena of interest in liquids have been derived from recent studies in our laboratory. In particular, new findings have contributed to identifying the structure of protonated complexes among species of varying proton affinities, and quantifying the variations in spectroscopic properties of chromophores as influenced by solvation and aggregation. 17 refs.

Castleman, A.W. Jr.

1991-01-01T23:59:59.000Z

338

Accelerated Molecular Dynamics Methods  

NLE Websites -- All DOE Office Websites (Extended Search)

Dynamics Methods Dynamics Methods for Infrequent Events Arthur F. Voter Theoretical Division Los Alamos National Laboratory Los Alamos, New Mexico U.S. Department of Energy Theory Focus Session on Hydrogen Storage Materials Crystal City, VA May 18, 2006 Los Alamos Acknowledgments Blas P. Uberuaga (LANL, MST-8) Francesco Montalenti (U. Milano-Bicocca) Graeme Henkelman (U. Texas at Austin) Timothy C. Germann (LANL, X-7) James A. Sprague (NRL) Mads Sorensen (Novo Nordisk A/S, Copenhagen) Sriram Swaminarayan (LANL, MST-8) Steve Stuart (Clemson) David Sholl (Carnegie Mellon) John Hamilton (Sandia) Wolfgang Windl (Ohio State) Roger Smith (U. Loughborough) Robin Grimes (Imperial College) Kurt Sickafus (LANL, MST-8) Jacques Amar (U. Toledo) DOE Office of Basic Energy Sciences Motorola Intel Los Alamos Outline

339

A non-adiabatic dynamics study of octatetraene: The radiationless conversion from S{sub 2} to S{sub 1}  

SciTech Connect

Simulation of the excited state dynamics of all-trans-1,3,5,7-octatetraene has been performed to investigate the ultrafast radiationless S{sub 2} ? S{sub 1} internal conversion process. Multireference configuration interaction with single excitation method has been employed to optimize the equilibrium structure of the excited states, as well as the S{sub 2}/S{sub 1} conical intersection, and to investigate the non-adiabatic molecular dynamics of the S{sub 2}/S{sub 1} state transition. At the conical intersection, the molecule is found to be distorted from the original planar trans structure to a nearly perpendicular conformation around C{sub 3}?C{sub 4} bond, with the torsion angle being about 107°. Such structural change can result in mutual approaching of states S{sub 2} and S{sub 1} in energy, and drastically increase the nonadiabatic coupling between the two states by destroying the inter-state symmetry prohibition in the electronic wavefunctions. Surface-hopping molecular dynamics simulations are performed to describe the non-adiabatic process. Upon the Franck-Condon excitation to the S{sub 2} state, the molecule quickly twists its C{sub 3}?C{sub 4} bond and approaches the conical intersection region, where it can undergo efficient internal conversion to S{sub 1}. The decay time constant (?) of S{sub 2} state is estimated to be around 251 fs by fitting the occupation number of average fraction of trajectories using an exponential damping function. This value is reasonably consistent with previous experimental measurements of around 300–400 fs.

Qu, Zexing, E-mail: jlqzx@163.com; Liu, Chungen, E-mail: cgliu@nju.edu.cn [Institute of Theoretical and Computational Chemistry, Key Laboratory of Mesoscopic Chemistry of the Ministry of Education (MOE), School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093 (China)] [Institute of Theoretical and Computational Chemistry, Key Laboratory of Mesoscopic Chemistry of the Ministry of Education (MOE), School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093 (China)

2013-12-28T23:59:59.000Z

340

Dynamic Adaptation using Xen  

SciTech Connect

The topic of virtualization has received renewed attention. Xen is a popular open source type-I hypervisor. The Xen hypervisor currently has limited capabilities for runtime modification to the core hypervisor, which impairs research into dynamic adaptation for system-level virtualization. This paper discusses recent investigations into the feasibility of extending Xen to support runtime adaptation for core hypervisor service, e.g., scheduler.

Naughton, III, Thomas J [ORNL; Vallee, Geoffroy R [ORNL; Scott, Stephen L [ORNL

2007-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "ultrafast solvation dynamics" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


341

Oligocene climate dynamics  

E-Print Network (OSTI)

, Sweden Received 18 April 2004; revised 30 July 2004; accepted 20 September 2004; published 8 December 2004. [1] A planktonic and benthic foraminiferal stable isotope stratigraphy of the Oligocene equatorial Pacific (Ocean Drilling Program, Site 1218...: Paleoceanography; 9355 Information Related to Geographic Region: Pacific Ocean; KEYWORDS: Oligocene, stable isotopes, ice volume Citation: Wade, B. S., and H. Pa?like (2004), Oligocene climate dynamics, Paleoceanography, 19, PA4019, doi:10.1029/2004PA001042. 1...

Wade, Bridget S.; Palike, Heiko

342

E-Print Network 3.0 - ap1000 advanced passive Sample Search Results  

NLE Websites -- All DOE Office Websites (Extended Search)

89, 232102 (Dec 2006) Influence of surface passivation on ultrafast carrier dynamics and terahertz radiation Summary: Appl. Phys. Lett. 89, 232102 (Dec 2006) Influence of surface...

343

Carrier-carrier scattering in the gain dynamics of InxGa1-xAs/AlyGa1-yAs diode lasers  

Science Journals Connector (OSTI)

Ultrafast optical nonlinearities in semiconductors play a central role in determining transient amplification and pulse-dependent gain saturation in diode lasers. Both carrier-phonon and carrier-carrier scattering are expected to determine the gain dynamics in these systems. We present a relaxation-time approximation model for carrier-carrier scattering in strained-layer lasers. The carrier-carrier scattering rates are determined using the quasiequilibrium distribution functions for a given background carrier density. The distribution function to which the photoexcited distribution relaxes is a Fermi-Dirac function where the chemical potential and temperature are self-consistently chosen so that both particle number and energy are conserved in the carrier-carrier scattering process. The relaxation approximation makes the problem an effective one-dimensional problem which can then be solved directly for the carrier distributions using an adaptive Runge-Kutta routine. This procedure is less computationally intensive than a full Monte Carlo simulation. The results show that the inclusion of carrier-carrier scattering improves previous results where only carrier-phonon scattering was included and that carrier-carrier scattering is necessary to produce heating of the carriers in the high-energy tails. © 1996 The American Physical Society.

G. D. Sanders; C.-K. Sun; B. Golubovic; J. G. Fujimoto; C. J. Stanton

1996-09-15T23:59:59.000Z

344

Definition: Dynamic Interchange Schedule Or Dynamic Schedule | Open Energy  

Open Energy Info (EERE)

Schedule Or Dynamic Schedule Schedule Or Dynamic Schedule Jump to: navigation, search Dictionary.png Dynamic Interchange Schedule Or Dynamic Schedule A telemetered reading or value that is updated in real time and used as a schedule in the AGC/ACE equation and the integrated value of which is treated as a schedule for interchange accounting purposes. Commonly used for scheduling jointly owned generation to or from another Balancing Authority Area.[1] Related Terms balancing authority, balancing authority area, smart grid References ↑ Glossary of Terms Used in Reliability Standards An in LikeLike UnlikeLike You like this.Sign Up to see what your friends like. line Glossary Definition Retrieved from "http://en.openei.org/w/index.php?title=Definition:Dynamic_Interchange_Schedule_Or_Dynamic_Schedule&oldid=502492

345

SDI: Statistical dynamic interactions  

SciTech Connect

We focus on the combined statistical and dynamical aspects of heavy ion induced reactions. The overall picture is illustrated by considering the reaction {sup 36}Ar + {sup 238}U at a projectile energy of 35 MeV/nucleon. We illustrate the time dependent bound excitation energy due to the fusion/relaxation dynamics as calculated with the Boltzmann master equation. An estimate of the mass, charge and excitation of an equilibrated nucleus surviving the fast (dynamic) fusion-relaxation process is used as input into an evaporation calculation which includes 20 heavy fragment exit channels. The distribution of excitations between residue and clusters is explicitly calculated, as is the further deexcitation of clusters to bound nuclei. These results are compared with the exclusive cluster multiplicity measurements of Kim et al., and are found to give excellent agreement. We consider also an equilibrated residue system at 25% lower initial excitation, which gives an unsatisfactory exclusive multiplicity distribution. This illustrates that exclusive fragment multiplicity may provide a thermometer for system excitation. This analysis of data involves successive binary decay with no compressional effects nor phase transitions. Several examples of primary versus final (stable) cluster decay probabilities for an A = 100 nucleus at excitations of 100 to 800 MeV are presented. From these results a large change in multifragmentation patterns may be understood as a simple phase space consequence, invoking neither phase transitions, nor equation of state information. These results are used to illustrate physical quantities which are ambiguous to deduce from experimental fragment measurements. 14 refs., 4 figs.

Blann, M.; Mustafa, M.G. (Lawrence Livermore National Lab., CA (USA)); Peilert, G.; Stoecker, H.; Greiner, W. (Frankfurt Univ. (Germany, F.R.). Inst. fuer Theoretische Physik)

1991-04-01T23:59:59.000Z

346

Perspective: Nonadiabatic dynamics theory  

Science Journals Connector (OSTI)

Nonadiabatic dynamics—nuclear motion evolving on multiple potential energy surfaces—has captivated the interest of chemists for decades. Exciting advances in experimentation and theory have combined to greatly enhance our understanding of the rates and pathways of nonadiabatic chemical transformations. Nevertheless there is a growing urgency for further development of theories that are practical and yet capable of reliable predictions driven by fields such as solar energy interstellar and atmospheric chemistry photochemistry vision single molecule electronics radiation damage and many more. This Perspective examines the most significant theoretical and computational obstacles to achieving this goal and suggests some possible strategies that may prove fruitful.

John C. Tully

2012-01-01T23:59:59.000Z

347

Dynamics of Charged Events  

SciTech Connect

In three spacetime dimensions the world volume of a magnetic source is a single point, an event. We make the event dynamical by regarding it as the imprint of a flux-carrying particle impinging from an extra dimension. This can be generalized to higher spacetime dimensions and to extended events. We exhibit universal observable consequences of the existence of events and argue that events are as important as particles or branes. We explain how events arise on the world volume of membranes in M theory, and in a Josephson junction in superconductivity.

Bachas, Constantin [Laboratoire de Physique Theorique de l'Ecole Normale Superieure, 24 rue Lhomond, 75231 Paris cedex (France); Bunster, Claudio [Centro de Estudios Cientificos (CECS), Avenida Arturo Prat 514, Valdivia (Chile); Henneaux, Marc [Physique Theorique et Mathematique, Universite Libre de Bruxelles and International Solvay Institutes, ULB Campus Plaine C.P. 231, 1050 Bruxelles (Belgium); Centro de Estudios Cientificos (CECS), Avenida Arturo Prat 514, Valdivia (Chile)

2009-08-28T23:59:59.000Z

348

Heat transfer dynamics  

SciTech Connect

As heat transfer technology increases in complexity, it becomes more difficult for those without thermal dynamics engineering training to choose between competitive heat transfer systems offered to meet their drying requirements. A step back to the basics of heat transfer can help professional managers and papermakers make informed decisions on alternative equipment and methods. The primary forms of heat and mass transfer are reviewed with emphasis on the basics, so a practical understanding of each is gained. Finally, the principles and benefits of generating infrared energy by combusting a gaseous hydrocarbon fuel are explained.

Smith, T.M. (Marsden, Inc., Pennsauken, NJ (United States))

1994-08-01T23:59:59.000Z

349

Gas-Phase Molecular Dynamics  

NLE Websites -- All DOE Office Websites (Extended Search)

Gas-Phase Molecular Dynamics Gas-Phase Molecular Dynamics The Gas-Phase Molecular Dynamics Group is dedicated to developing and applying spectroscopic and theoretical tools to challenging problems in chemical physics related to reactivity, structure, dynamics and kinetics of transient species. Recent theoretical work has included advances in exact variational solution of vibrational quantum dynamics, suitable for up to five atoms in systems where large amplitude motion or multiple strongly coupled modes make simpler approximations inadequate. Other theoretical work, illustrated below, applied direct dynamics, quantum force trajectory calculations to investigate a series of reactions of the HOCO radical. The potential energy surface for the OH + CO/ H + CO2 reaction, showing two barriers (TS1 and TS2) and the deep HOCO well along the minimum energy pathway. The inset figure shows the experimental and calculated reactivity of HOCO with selected collision partners. See J.S. Francisco, J.T. Muckerman and H.-G. Yu, "HOCO radical chemistry,"

350

Nuclear Matter and Nuclear Dynamics  

E-Print Network (OSTI)

Highlights on the recent research activity, carried out by the Italian Community involved in the "Nuclear Matter and Nuclear Dynamics" field, will be presented.

M Colonna

2009-02-26T23:59:59.000Z

351

Dynamic simulation of Odoo  

Science Journals Connector (OSTI)

Abstract The thermal habits of Odoo were examined and energy consumption data were also predicted. Special tests were performed for the time of the competition, and whole year was also analysed. The climatic data were of Madrid as the competition took place there. The modelling environment was MATLAB's Simulink with a built-in module of Simscape. It is for especially examining thermal behaviours. MATLAB itself is capable of solving differential equations by time, for this reason dynamic simulations can be performed. First the building structure was created, and then the heatflows affecting the internal temperature were added. In this paper detailed process of creating the model is presented, and some results are discussed, including some possibilities of further improvements.

Gábor Haas-Schnabel; Csaba Szikra

2014-01-01T23:59:59.000Z

352

Atmospheric Dynamics of Exoplanets  

E-Print Network (OSTI)

The characterization of exoplanetary atmospheres has come of age in the last decade, as astronomical techniques now allow for albedos, chemical abundances, temperature profiles and maps, rotation periods and even wind speeds to be measured. Atmospheric dynamics sets the background state of density, temperature and velocity that determines or influences the spectral and temporal appearance of an exoplanetary atmosphere. Hot exoplanets are most amenable to these characterization techniques; in the present review, we focus on highly-irradiated, large exoplanets (the "hot Jupiters"), as astronomical data begin to confront theoretical questions. We summarize the basic atmospheric quantities inferred from the astronomical observations. We review the state of the art by addressing a series of current questions and look towards the future by considering a separate set of exploratory questions. Attaining the next level of understanding will require a concerted effort of constructing multi-faceted, multi-wavelength dat...

Heng, Kevin

2014-01-01T23:59:59.000Z

353

Probing Single-Molecule Protein Conformational Dynamics. | EMSL  

NLE Websites -- All DOE Office Websites (Extended Search)

Single-Molecule Protein Conformational Dynamics. Probing Single-Molecule Protein Conformational Dynamics. Abstract: Protein conformational fluctuations and dynamics, often...

354

Risk Price Dynamics Jaroslav Borovicka  

E-Print Network (OSTI)

Risk Price Dynamics Jaroslav Borovicka University of Chicago Lars Peter Hansen University November 11, 2009 Abstract We present a novel approach to depicting asset pricing dynamics by characterizing shock exposures and prices for alternative investment horizons. We quantify the shock exposures

Hansen, Lars Peter

355

Extremes in Chaotic Dynamical Systems  

E-Print Network (OSTI)

Extremes in Chaotic Dynamical Systems Valerio Lucarini valerio.lucarini@uni-hamburg.de D. Faranda Vortragsthema Datum #12;1. Introduction 2. Classical Theory: Extreme Values for i.i.d. Variables 3. Extreme Values in Dynamical Systems: Theoretical Background 4. Numerical Algorithms for studying Extremes 5

356

Status of dynamical ensemble generation  

E-Print Network (OSTI)

I give an overview of current and future plans of dynamical QCD ensemble generation activities. A comparison of simulation cost between different discretizations is made. Recent developments in techniques and algorithms used in QCD dynamical simulations, especially mass reweighting, are also discussed.

Chulwoo Jung

2010-01-06T23:59:59.000Z

357

Electronic structure, molecular orientation, charge transfer dynamics and solar cells performance in donor/acceptor copolymers and fullerene: Experimental and theoretical approaches  

SciTech Connect

By combining experimental and theoretical approaches, the electronic structure, molecular orientation, charge transfer dynamics and solar cell performance in donor/acceptor copolymer poly[2,7-(9,9-bis(2-ethylhexyl)-dibenzosilole)-alt-4,7-bis(thiophen-2-yl) benzo-2,1,3-thiadiazole] (PSiF-DBT) films and blended with 6,6.-phenyl-C 61-butyric acid methyl ester (PSiF-DBT:PCBM) were investigated. Good agreement between experimental and theoretical PSiF-DBT UV-Vis absorption spectrum is observed and the main molecular orbitals contributing to the spectrum were determined using DFT single point calculations. Non-coplanar configuration was determined by geometric optimization calculation in isolated PSiF-DBT pentamer and corroborated by angular variation of the sulphur 1s near-edge X-ray absorption fine structure (NEXAFS) spectra. Edge-on and plane-on molecular orientations were obtained for thiophene and benzothiadiazole units, respectively. A power conversion efficiency up to 1.58%, open circuit voltage of 0.51 V, short circuit current of 8.71 mA/cm{sup 2} and a fill factor of 35% was obtained using blended PSiF-DBT:PCBM as active layer in a bulk heterojunction solar cell. Ultrafast electron dynamics in the low-femtosecond regime was evaluated by resonant Auger spectroscopy using the core-hole clock methodology around sulphur 1s absorption edge. Electron delocalization times for PSiF-DBT and PSiF-DBT:PCBM polymeric films were derived for selected excitation energies corresponding to the main transitions in the sulphur 1s NEXAFS spectra. The mixture of PSiF-DBT with PCBM improves the charge transfer process involving the ?* molecular orbital of the thiophene units.

Garcia-Basabe, Y.; Borges, B. G. A. L.; Rocco, M. L. M., E-mail: lsroman@fisica.ufpr.br, E-mail: luiza@iq.ufrj.br [Institute of Chemistry, Federal University of Rio de Janeiro, Rio de Janeiro 21941-909 (Brazil); Marchiori, C. F. N.; Yamamoto, N. A. D.; Koehler, M.; Roman, L. S., E-mail: lsroman@fisica.ufpr.br, E-mail: luiza@iq.ufrj.br [Departament of Physics, Federal University of Paraná, Curitiba 81531-990 (Brazil); Macedo, A. G. [Departament of Physics, Technological Federal University of Paraná, Curitiba 80230-901 (Brazil)

2014-04-07T23:59:59.000Z

358

Dynamical decoupling induced renormalization of the non-Markovian dynamics  

E-Print Network (OSTI)

In this work we develop a numerical framework to investigate the renormalization of the non-Markovian dynamics of an open quantum system to which dynamical decoupling is applied. We utilize a non-Markovian master equation which is derived from the non-Markovian quantum trajectories formalism. It contains incoherent Markovian dynamics and coherent Schr\\"odinger dynamics as its limiting cases and is capable of capture the transition between them. We have performed comprehensive simulations for the cases in which the system is either driven by the Ornstein-Uhlenbeck noise or or is described by the spin-boson model. The renormalized dynamics under bang-bang control and continuous dynamical decoupling are simulated. Our results indicate that the renormalization of the non-Markovian dynamics depends crucially on the spectral density of the environment and the envelop of the decoupling pulses. The framework developed in this work hence provides an unified approach to investigate the efficiency of realistic decoupling pulses. This work also opens a way to further optimize the decoupling via pulse shaping.

Pochung Chen

2006-09-28T23:59:59.000Z

359

Proceedings of the Seventeenth DOE Solar Photochemistry Research Conference  

SciTech Connect

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.

Not Available

1993-12-31T23:59:59.000Z

360

[Clusters: Elucidating the dynamics of ionization events and ensuing reactions in the condensed phase]. Brief summary of accomplishments  

SciTech Connect

New insight into a variety of phenomena of interest in liquids have been derived from recent studies in our laboratory. In particular, new findings have contributed to identifying the structure of protonated complexes among species of varying proton affinities, and quantifying the variations in spectroscopic properties of chromophores as influenced by solvation and aggregation. 17 refs.

Castleman, A.W. Jr.

1991-12-31T23:59:59.000Z

Note: This page contains sample records for the topic "ultrafast solvation dynamics" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


361

Seasonality and dynamics of whooping cough.  

E-Print Network (OSTI)

??Whooping cough (pertussis) dynamics provide an interesting disease ecology case study. Unlike other childhood diseases, the observed patterns of pertussis dynamics are found very diverse… (more)

Nguyen, Hanh Thi Hong

2007-01-01T23:59:59.000Z

362

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...

363

16.07 Dynamics, Fall 2004  

E-Print Network (OSTI)

Dynamics starts with fundamentals of Newtonian mechanics. Further topics include kinematics, particle dynamics, motion relative to accelerated reference frames, work and energy, impulse and momentum, systems of particles ...

Peraire, Jaume

364

Soil Machine Dynamics Ltd | Open Energy Information  

Open Energy Info (EERE)

Dynamics Ltd Jump to: navigation, search Name: Soil Machine Dynamics Ltd Region: United Kingdom Sector: Marine and Hydrokinetic Website: http:http:smd.co.ukproduc This company...

365

Hamilton Dynamics on Clifford Kaehler Manifolds  

E-Print Network (OSTI)

This paper presents Hamilton dynamics on Clifford Kaeler manifolds. In the end, the some results related to Clifford Kaehler dynamical systems are also discussed.

Mehmet Tekkoyun

2009-02-24T23:59:59.000Z

366

Fermionic Molecular Dynamics for nuclear dynamics and thermodynamics  

E-Print Network (OSTI)

A new Fermionic Molecular Dynamics (FMD) model based on a Skyrme functional is proposed in this paper. After introducing the basic formalism, some first applications to nuclear structure and nuclear thermodynamics are presented

K. H. O. Hasnaoui; Ph. Chomaz; F. Gulminelli

2008-12-02T23:59:59.000Z

367

Computational fluid dynamic applications  

SciTech Connect

The rapid advancement of computational capability including speed and memory size has prompted the wide use of computational fluid dynamics (CFD) codes to simulate complex flow systems. CFD simulations are used to study the operating problems encountered in system, to evaluate the impacts of operation/design parameters on the performance of a system, and to investigate novel design concepts. CFD codes are generally developed based on the conservation laws of mass, momentum, and energy that govern the characteristics of a flow. The governing equations are simplified and discretized for a selected computational grid system. Numerical methods are selected to simplify and calculate approximate flow properties. For turbulent, reacting, and multiphase flow systems the complex processes relating to these aspects of the flow, i.e., turbulent diffusion, combustion kinetics, interfacial drag and heat and mass transfer, etc., are described in mathematical models, based on a combination of fundamental physics and empirical data, that are incorporated into the code. CFD simulation has been applied to a large variety of practical and industrial scale flow systems.

Chang, S.-L.; Lottes, S. A.; Zhou, C. Q.

2000-04-03T23:59:59.000Z

368

Dynamics of dark energy  

E-Print Network (OSTI)

In this paper we review in detail a number of approaches that have been adopted to try and explain the remarkable observation of our accelerating Universe. In particular we discuss the arguments for and recent progress made towards understanding the nature of dark energy. We review the observational evidence for the current accelerated expansion of the universe and present a number of dark energy models in addition to the conventional cosmological constant, paying particular attention to scalar field models such as quintessence, K-essence, tachyon, phantom and dilatonic models. The importance of cosmological scaling solutions is emphasized when studying the dynamical system of scalar fields including coupled dark energy. We study the evolution of cosmological perturbations allowing us to confront them with the observation of the Cosmic Microwave Background and Large Scale Structure and demonstrate how it is possible in principle to reconstruct the equation of state of dark energy by also using Supernovae Ia observational data. We also discuss in detail the nature of tracking solutions in cosmology, particle physics and braneworld models of dark energy, the nature of possible future singularities, the effect of higher order curvature terms to avoid a Big Rip singularity, and approaches to modifying gravity which leads to a late-time accelerated expansion without recourse to a new form of dark energy.

Edmund J. Copeland; M. Sami; Shinji Tsujikawa

2006-06-16T23:59:59.000Z

369

Synchronized dynamic dose reconstruction  

SciTech Connect

Variations in target volume position between and during treatment fractions can lead to measurable differences in the dose distribution delivered to each patient. Current methods to estimate the ongoing cumulative delivered dose distribution make idealized assumptions about individual patient motion based on average motions observed in a population of patients. In the delivery of intensity modulated radiation therapy (IMRT) with a multi-leaf collimator (MLC), errors are introduced in both the implementation and delivery processes. In addition, target motion and MLC motion can lead to dosimetric errors from interplay effects. All of these effects may be of clinical importance. Here we present a method to compute delivered dose distributions for each treatment beam and fraction, which explicitly incorporates synchronized real-time patient motion data and real-time fluence and machine configuration data. This synchronized dynamic dose reconstruction method properly accounts for the two primary classes of errors that arise from delivering IMRT with an MLC: (a) Interplay errors between target volume motion and MLC motion, and (b) Implementation errors, such as dropped segments, dose over/under shoot, faulty leaf motors, tongue-and-groove effect, rounded leaf ends, and communications delays. These reconstructed dose fractions can then be combined to produce high-quality determinations of the dose distribution actually received to date, from which individualized adaptive treatment strategies can be determined.

Litzenberg, Dale W.; Hadley, Scott W.; Tyagi, Neelam; Balter, James M.; Ten Haken, Randall K.; Chetty, Indrin J. [University of Michigan, Ann Arbor, Michigan 48109 (United States)

2007-01-15T23:59:59.000Z

370

Dynamical Properties of Interaction Data  

E-Print Network (OSTI)

Network dynamics are typically presented as a time series of network properties captured at each period. The current approach examines the dynamical properties of transmission via novel measures on an integrated, temporally extended network representation of interaction data across time. Because it encodes time and interactions as network connections, static network measures can be applied to this "temporal web" to reveal features of the dynamics themselves. Here we provide the technical details and apply it to agent-based implementations of the well-known SEIR and SEIS epidemiological models.

Bramson, Aaron

2015-01-01T23:59:59.000Z

371

A Dynamical Approach to Temperature  

E-Print Network (OSTI)

We present a new dynamical approach for measuring the temperature of a Hamiltonian dynamical system in the micro canonical ensemble of thermodynamics. We show that under the hypothesis of ergodicity the temperature can be computed as a time-average of the functional, div(grad H/|grad H|^2), on the energy-surface. Our method not only yields an efficient computational approach for determining the temperature it also provides an intrinsic link between dynamical systems theory and the statistical mechanics of Hamiltonian systems.

Hans Henrik Rugh

1997-01-30T23:59:59.000Z

372

Dynamics of femtosecond laser produced tungsten nanoparticle plumes  

SciTech Connect

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.

Harilal, S. S.; Hassanein, A. [Center for Materials Under Extreme Environment, School of Nuclear Engineering, Purdue University, West Lafayette, Indiana 47907 (United States)] [Center for Materials Under Extreme Environment, School of Nuclear Engineering, Purdue University, West Lafayette, Indiana 47907 (United States); Farid, N. [Center for Materials Under Extreme Environment, School of Nuclear Engineering, Purdue University, West Lafayette, Indiana 47907 (United States) [Center for Materials Under Extreme Environment, School of Nuclear Engineering, Purdue University, West Lafayette, Indiana 47907 (United States); School of Physics and Optical Engineering, Dalian University of Technology, Dalian 116024 (China); Kozhevin, V. M. [Ioffe Physics Technical Institute, Russian Academy of Sciences, St. Petersburg 194021 (Russian Federation)] [Ioffe Physics Technical Institute, Russian Academy of Sciences, St. Petersburg 194021 (Russian Federation)

2013-11-28T23:59:59.000Z

373

Observation of a remarkable temperature effect in the hydrogen bonding structure and dynamics of the CN-(H2O) cluster  

SciTech Connect

The CN-(H2O) cluster represents a model diatomic monohydrate with multiple solvation sites. We report joint experimental and theoretical studies of its structure and dynamics using temperature-controlled photoelectron spectroscopy (PES) and ab-initio electronic structure calculations. The observed PES spectra of CN-(H2O) display a remarkable temperature effect, namely that the T=12 K spectrum shows an unexpectedly large blue shift of 0.25 eV in the electron binding energy relative to the Room Temperature (RT) spectrum. Extensive theoretical analysis of the potential energy function (PEF) of the cluster at the CCSD(T) level of theory reveal the existence of two nearly isoenergetic isomers corresponding to H2O forming a H-bond with either the C or the N atom, respectively. This results in four topologically distinct minima, i.e., CN-(HaOHb), CN-(HbOHa), NC-(HaOHb) and NC-(HbOHa). There are two main pathways connecting these minima: (i) CN- tumbling relative to water and (ii) water rocking relative to CN-. The relative magnitude of the barriers associated with these two motions reverses between low [pathway (i) is preferred] and high [pathway (ii) is preferred] temperatures. As a result, at T=12 K the cluster adopts a structure that is close to the minimum energy CN-(H2O) configuration, while at RT it can effectively access regions of the PEF close to the transition state for pathway (ii), explaining the surprisingly large spectral shift between the 12 K and RT PES spectra. This work was supported by the Division of Chemical Sciences, Geosciences and Biosciences, Office of Basic Energy Sciences, US Department of Energy. Battelle operates Pacific Northwest National Laboratory for the US Department of Energy.

Wang, Xue B.; Werhahn, Jasper C.; Wang, Lai S.; Kowalski, Karol; Laubereau, Alfred; Xantheas, Sotiris S.

2009-09-03T23:59:59.000Z

374

LANL | Physics | Dynamic Plutonium Experiments  

NLE Websites -- All DOE Office Websites (Extended Search)

Dynamic plutonium experiments Dynamic plutonium experiments Since the end of nuclear testing the nation has had to rely on sophisticated computer models to ensure the safety and reliability of the nuclear weapons stockpile. This program is known as science-based stockpile stewardship. Despite possessing the world's fastest computers and most advanced modeling capability, the behavior of materials under dynamic loads that occur in a nuclear weapon are difficult to accurately model. The Dynamic Plutonium experimental program carries out experiments at the Nevada National Security Site on plutonium driven by high explosives. These experiments are needed to measure and understand the behavior of plutonium under extreme conditions. Physics Division has unique capabilities in high-speed x-ray imaging and velocimetry (measuring the

375

THz Dynamic Nuclear Polarization NMR  

E-Print Network (OSTI)

Dynamic nuclear polarization (DNP) increases the sensitivity of nuclear magnetic resonance (NMR) spectroscopy by using high frequency microwaves to transfer the polarization of the electrons to the nuclear spins. The ...

Nanni, Emilio Alessandro

376

Predictive Models of Forest Dynamics  

Science Journals Connector (OSTI)

...currently highly uncertain (Fig. 1), making vegetation dynamics one of the largest sources of uncertainty in Earth system models. Reducing this uncertainty requires work on several fronts. For example, physiological parameters need to be...

Drew Purves; Stephen Pacala

2008-06-13T23:59:59.000Z

377

Gas-phase chemical dynamics  

SciTech Connect

Research in this program is directed towards the spectroscopy of small free radicals and reactive molecules and the state-to-state dynamics of gas phase collision, energy transfer, and photodissociation phenomena. Work on several systems is summarized here.

Weston, R.E. Jr.; Sears, T.J.; Preses, J.M. [Brookhaven National Laboratory, Upton, NY (United States)

1993-12-01T23:59:59.000Z

378

Dynamic systems and subadditive functionals  

E-Print Network (OSTI)

Consider a problem where a number of dynamic systems are required to travel between points in minimum time. The study of this problem is traditionally divided into two parts: A combinatorial part that assigns points to ...

Itani, Sleiman M

2009-01-01T23:59:59.000Z

379

Actin Dynamics in Aspergillus nidulans  

E-Print Network (OSTI)

used to label all three actin structures in fungi. Lifeact is a 17 amino acid peptide derived from the Saccharomyces cerevisiae actin binding protein Abp140p. To better understand actin dynamics in living cells, A. nidulans was transformed...

Quintanilla, Laura

2013-04-08T23:59:59.000Z

380

Cluster Dynamics of Planetary Waves  

E-Print Network (OSTI)

The dynamics of nonlinear atmospheric planetary waves is determined by a small number of independent wave clusters consisting of a few connected resonant triads. We classified the different types of connections between neighboring triads that determine the general dynamics of a cluster. Each connection type corresponds to substantially different scenarios of energy flux among the modes. The general approach can be applied directly to various mesoscopic systems with 3-mode interactions, encountered in hydrodynamics, astronomy, plasma physics, chemistry, medicine, etc.

Elena Kartashova; Victor S. L'vov

2008-11-05T23:59:59.000Z

Note: This page contains sample records for the topic "ultrafast solvation dynamics" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


381

Dynamic roughening of directed lines  

Science Journals Connector (OSTI)

We study the fluctuations of a stretched string, e.g., a vortex line, moving in a random medium. A pair of nonlinear equations are proposed to describe the evolution of longitudinal and transverse coordinates. The dynamic scaling of the fluctuations is studied analytically (by renormalization group) and numerically. In most cases the fluctuations are superdiffusive, governed by a dynamic exponent z=3/2.

Deniz Erta? and Mehran Kardar

1992-08-10T23:59:59.000Z

382

HAWT performance with dynamic stall  

SciTech Connect

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.

Hibbs, B.D.

1986-02-01T23:59:59.000Z

383

Nonstatistical dynamics on the caldera  

E-Print Network (OSTI)

We explore both classical and quantum dynamics of a model potential exhibiting a caldera: that is, a shallow potential well with two pairs of symmetry related index one saddles associated with entrance/exit channels. Classical trajectory simulations at several different energies confirm the existence of the `dynamical matching' phenomenon originally proposed by Carpenter, where the momentum direction associated with an incoming trajectory initiated at a high energy saddle point determines to a considerable extent the outcome of the reaction (passage through the diametrically opposing exit channel). By studying a `stretched' version of the caldera model, we have uncovered a generalized dynamical matching: bundles of trajectories can reflect off a hard potential wall so as to end up exiting predominantly through the transition state opposite the reflection point. We also investigate the effects of dissipation on the classical dynamics. In addition to classical trajectory studies, we examine the dynamics of quantum wave packets on the caldera potential (stretched and unstretched). These computations reveal a quantum mechanical analogue of the `dynamical matching' phenomenon, where the initial expectation value of the momentum direction for the wave packet determines the exit channel through which most of the probability density passes to product.

Peter Collins; Zeb C. Kramer; Barry K. Carpenter; Gregory S. Ezra; Stephen Wiggins

2014-05-09T23:59:59.000Z

384

Experimental studies on passive dynamic bipedal walking  

Science Journals Connector (OSTI)

Passive dynamic walking is a gait developed, partially or in whole, by the energy provided by gravity. The research on passive dynamic bipedal walking helps create an understanding of walking mechanics. Moreover, the experimental passive dynamic research ... Keywords: Design and testing, Experiment, Gait patterns, Passive dynamic walking, Treadmill

Kazi Rushdi, Derek Koop, Christine Q. Wu

2014-04-01T23:59:59.000Z

385

SOM 825 Advanced Mathematical Programming: Dynamic Network Systems  

E-Print Network (OSTI)

, dynamic spatial price equilibrium problems, dynamic transportation problems (both fixed and elastic demand Formulation Dynamic Financial Network Models Dynamic Traffic Network Models and Algorithms ** Elastic Demand (Classical and Spatial) Dynamic Spatial Price Models and Algorithms ** Quantity Formulation ** Price

Nagurney, Anna

386

Simple Dynamic Gasifier Model That Runs in Aspen Dynamics  

SciTech Connect

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.

Robinson, P.J.; Luyben, W.L. [Lehigh University, Bethlehem, PA (United States). Dept. of Chemical Engineering

2008-10-15T23:59:59.000Z

387

Modeling Molecular Dynamics from Simulations  

SciTech Connect

Many important processes in biology occur at the molecular scale. A detailed understanding of these processes can lead to significant advances in the medical and life sciences. For example, many diseases are caused by protein aggregation or misfolding. One approach to studying these systems is to use physically-based computational simulations to model the interactions and movement of the molecules. While molecular simulations are computationally expensive, it is now possible to simulate many independent molecular dynamics trajectories in a parallel fashion by using super- or distributed- computing methods such as Folding@Home or Blue Gene. The analysis of these large, high-dimensional data sets presents new computational challenges. In this seminar, I will discuss a novel approach to analyzing large ensembles of molecular dynamics trajectories to generate a compact model of the dynamics. This model groups conformations into discrete states and describes the dynamics as Markovian, or history-independent, transitions between the states. I will discuss why the Markovian state model (MSM) is suitable for macromolecular dynamics, and how it can be used to answer many interesting and relevant questions about the molecular system. I will also discuss many of the computational and statistical challenges in building such a model, such as how to appropriately cluster conformations, determine the statistical reliability, and efficiently design new simulations.

Hinrichs, Nina Singhal (University of Chicago) [University of Chicago

2009-01-28T23:59:59.000Z

388

New Polymer Architectures for Imidazole Solvating groups, Anion...  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

electrode particles conducting carbon particle Gas Phase *Transport of gases and ions through crowded polymer-solid interfaces where the electrolyte mobility is restricted....

389

Modeling Free Energies of Solvation in Olive Oil  

Science Journals Connector (OSTI)

In particular, it has been shown that these partition coefficients correlate with the partitioning of the drugs into rat and human tissue. ... Meyer, K. H.; Hopff, H. Theory of narcosis by inhalation anesthetics. ... A hypothesis relating oil-water partition coefficients and vapor pressures of nonelectrolytes to their penetration rates through biological membranes J. Theor. ...

Adam C. Chamberlin; David G. Levitt; Christopher J. Cramer; Donald G. Truhlar

2008-10-16T23:59:59.000Z

390

Linking Ion Solvation and Lithium Battery Electrolyte Properties  

Energy.gov (U.S. Department of Energy (DOE))

2010 DOE Vehicle Technologies and Hydrogen Programs Annual Merit Review and Peer Evaluation Meeting, June 7-11, 2010 -- Washington D.C.

391

Linking Ion Solvation and Lithium Battery Electrolyte Properties...  

Energy Savers (EERE)

Electrolyte Properties 2010 DOE Vehicle Technologies and Hydrogen Programs Annual Merit Review and Peer Evaluation Meeting, June 7-11, 2010 -- Washington D.C....

392

Temperature-dependent solvation modulates the dimensions of disordered proteins  

Science Journals Connector (OSTI)

...14614 . 9 Tran HT Mao A Pappu RV ( 2008 ) Role of backbone-solvent...Jayaraman M Frieden C Wetzel R Pappu RV ( 2006 ) Fluorescence correlation spectroscopy...CAMPARI code, and Rohit Pappu and Andreas Vitalis for...National Institutes of Health (R.B.B.), and National...

René Wuttke; Hagen Hofmann; Daniel Nettels; Madeleine B. Borgia; Jeetain Mittal; Robert B. Best; Benjamin Schuler

2014-01-01T23:59:59.000Z

393

Fissile solution dynamics: Student research  

SciTech Connect

There are two research projects in criticality safety at the University of Arizona: one in dynamic simulation of hypothetical criticality accidents in fissile solutions, and one in criticality benchmarks using transport theory. We have used the data from nuclear excursions in KEWB, CRAC, and SILENE to help in building models for solution excursions. An equation of state for liquids containing gas bubbles has been developed and coupled to point-reactor dynamics in an attempt to predict fission rate, yield, pressure, and kinetic energy. It appears that radiolytic gas is unimportant until after the first peak, but that it does strongly affect the shape of the subsequent power decrease and also the dynamic pressure.

Hetrick, D.L.

1994-09-01T23:59:59.000Z

394

Dynamical 3-Space: Emergent Gravity  

E-Print Network (OSTI)

The laws of gravitation devised by Newton, and by Hilbert and Einstein, have failed many experimental and observational tests, namely the bore hole g anomaly, flat rotation curves for spiral galaxies, supermassive black hole mass spectrum, uniformly expanding universe, cosmic filaments, laboratory G measurements, galactic EM bending, precocious galaxy formation,.. The response has been the introduction of the new epicycles: ``dark matter", ``dark energy", and others. To understand gravity we must restart with the experimental discoveries by Galileo, and following a heuristic argument we are led to a uniquely determined theory of a dynamical 3-space. That 3-space exists has been missed from the beginning of physics, although it was 1st directly detected by Michelson and Morley in 1887. Uniquely generalising the quantum theory to include this dynamical 3-space we deduce the response of quantum matter and show that it results in a new account of gravity, and explains the above anomalies and others. The dynamical...

Cahill, Reginald T

2011-01-01T23:59:59.000Z

395

Dynamics of Block Copolymer Nanocomposites  

SciTech Connect

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.

Mochrie, Simon G. J.

2014-09-09T23:59:59.000Z

396

Ultrafast Nonlinear Spectroscopy of Semiconducting Carbon Nanotubes  

E-Print Network (OSTI)

P. ; Pshenichnikov, M. S. ; Wiersma, D. A. Chem. Phys. Lett.Fidder, H. ; Terpstra, J. ; Wiersma, D. A. J. Chem. Phys.Pshenichnikov, and D.A. Wiersma. On the relation between the

Graham, Matthew Werden

2010-01-01T23:59:59.000Z

397

Ultrafast Detonation of Hydrazoic Acid (HN3)  

Science Journals Connector (OSTI)

The fastest self-sustained chemical reactions in nature occur during detonation of energetic materials where reactions are thought to occur on nanosecond or longer time scales in carbon-containing materials. Here we perform the first atomistic simulation of an azide energetic material, HN3, from the beginning to the end of the chemical evolution and find that the time scale for complete decomposition is a mere 10 ps, orders of magnitude shorter than that of secondary explosives and approaching the fundamental limiting time scale for chemistry; i.e., vibrational time scale. We study several consequences of the short time scale including a state of vibrational disequilibrium induced by the fast transformations.

Evan J. Reed; Alejandro W. Rodriguez; M. Riad Manaa; Laurence E. Fried; Craig M. Tarver

2012-07-17T23:59:59.000Z

398

Ultrafast Nonlinear Spectroscopy of Semiconducting Carbon Nanotubes  

E-Print Network (OSTI)

metallic nanotubes . . . . . . . . . . . . . . . . . Carbon2 Carbon Nanotubes Physical and ElectronicStructure of Carbon Nanotubes . . . . . . . . . .

Graham, Matthew Werden

2010-01-01T23:59:59.000Z

399

Ultrafast Nonlinear Spectroscopy of Semiconducting Carbon Nanotubes  

E-Print Network (OSTI)

Exciton binding energies in carbon nanotubes from two-photonExciton binding energies in carbon nanotubes from two-photonoptical transition energies of carbon nanotubes: the role of

Graham, Matthew Werden

2010-01-01T23:59:59.000Z

400

Ultrafast Intramolecular Energy Transfer in Water  

Science Journals Connector (OSTI)

An unexpectedly fast (0.2 ps) intramolecular energy conversion occurring in H2O molecules has been revealed using frequency-resolved mid-infrared pump-probe spectroscopy in the spectral region of the OH-stretchin...

Dan Cringus; Thomas 1. C. Jansen; Maxim S. Pshenichnikov…

2007-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "ultrafast solvation dynamics" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


401

Ultrafast Nonlinear Spectroscopy of Semiconducting Carbon Nanotubes  

E-Print Network (OSTI)

Bond, et al. , Nano Lett. 6, 1603 (2006). [18] H. Htoon, M.P. Nano Lett. 2006, 6, 1603. [14] Htoon, H. ; O’Connell, M.nanotubes. Nano Lett. , 6(8):1603–1608, 2006. [21] M.S.

Graham, Matthew Werden

2010-01-01T23:59:59.000Z

402

Multichannel photodiode detector for ultrafast optical spectroscopy  

E-Print Network (OSTI)

Construction and characterization of a multichannel photodiode detector based on commercially available components with high signal to noise of $\\sim10^{6}$ and a rapid frame rate, suitable for time resolved femtosecond spectroscopy with high repetition femtosecond sources, is presented.

Mertelj, T; Borzda, T; Vaskivskyi, I; Pogrebna, A; Mihailovic, D

2014-01-01T23:59:59.000Z

403

Ultrafast Spectroscopy of Correlated Electron Systems  

E-Print Network (OSTI)

in the materi- als science of magnetic semiconductors. Thein zinc-blende magnetic semiconductors. ” Science 287, 1019–

Schmid, Benjamin Andrew

2009-01-01T23:59:59.000Z

404

LED / Lighting Ultrafast Submicron Thermoreflectance Imaging  

E-Print Network (OSTI)

This Both the miniaturization of electronic and optoelectronic devices and circuits and the increased. For optoelectronic devices, an additional scheme is required to separate electro-luminescence and the reflected

405

Ultrafast Nonlinear Spectroscopy of Semiconducting Carbon Nanotubes  

E-Print Network (OSTI)

2 Carbon Nanotubes Physical andElectronic Structure of Carbon Nanotubes . . . . . . . . . .Photophysics in Semiconducting Carbon Nanotubes . . . . .

Graham, Matthew Werden

2010-01-01T23:59:59.000Z

406

Ames Lab 101: Ultrafast Magnetic Switching  

SciTech Connect

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.

Jigang Wang

2013-04-08T23:59:59.000Z

407

Ultrafast Interfacial Proton-Coupled Electron Transfer  

Science Journals Connector (OSTI)

...environmental remediation is the activation...and neighboring water molecules...geometry of the ground state and...relevant to chemical remediation and the destruction...Calculations where the ground state is optimized...electron (the true ground state of our...7732-18-5 Water 7782-39-0...

Bin Li; Jin Zhao; Ken Onda; Kenneth D. Jordan; Jinlong Yang; Hrvoje Petek

2006-03-10T23:59:59.000Z

408

Ultrafast Optical Pulses: Synthesis and Applications  

E-Print Network (OSTI)

-sinusoidal waveforms. The setup allows for both coarse, manual phase adjustments and programmable ?ne-tuning of spectral phases. A ?at spectral phase across these 5 frequency-separated sub-bands is achieved, which implies generation of isolated 2 to 3 optical...

Wang, Kai

2013-12-11T23:59:59.000Z

409

Ames Lab 101: Ultrafast Magnetic Switching  

ScienceCinema (OSTI)

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.

Jigang Wang

2013-06-05T23:59:59.000Z

410

Dynamical model of Ising spins  

Science Journals Connector (OSTI)

A two-dimensional dynamical model of Ising spins is introduced. Since we were not able to define energy in our system, we introduced an object called the disagreement function. This function controls the dynamics—minimizing it locally we decide upon spin flipping. Amazingly, local minimization of the disagreement function can lead to an increase of its global value. We present the phase diagram of the system and show that exactly the same initial conditions can lead the system to one of several, completely different final steady states.

Katarzyna Sznajd-Weron

2004-09-30T23:59:59.000Z

411

Fairness and dynamic pricing: comments  

SciTech Connect

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)

Hogan, William W.

2010-07-15T23:59:59.000Z

412

Model system for slow dynamics  

Science Journals Connector (OSTI)

Systems whose dynamics are described by a quasilogarithmic or stretched-exponential time dependence are usually fitted by models which use disorder to create a distribution of relaxation times. Here we describe a model which decays slowly towards equilibrium but does not require disorder to provide the slow dynamics. The model consists of a spin system with the spins interacting via the dipole-dipole interaction. The model is able to replicate the more pronounced features observed in the magnetization decay of magnetic systems and high-temperature superconductors.

D. K. Lottis; R. M. White; E. Dan Dahlberg

1991-07-15T23:59:59.000Z

413

Dynamic Conductance of Carbon Nanotubes  

Science Journals Connector (OSTI)

The dynamic conductance of carbon nanotubes was investigated using the nonequilibrium Green's function formalism within the context of a tight-binding model. Specifically, we have studied the ac response of tubes of different helicities, both with and without defects, and an electronic heterojunction. Because of the induced displacement currents, the dynamic conductance of the nanotubes differs significantly from the dc conductance displaying both capacitive and inductive responses. The important role of photon-assisted transport through nanotubes is revealed and its implications for experiments discussed.

Christopher Roland; Marco Buongiorno Nardelli; Jian Wang; Hong Guo

2000-03-27T23:59:59.000Z

414

Theoretical studies of combustion dynamics  

SciTech Connect

The basic objectives of this research program are to develop and apply theoretical techniques to fundamental dynamical processes of importance in gas-phase combustion. There are two major areas currently supported by this grant. One is reactive scattering of diatom-diatom systems, and the other is the dynamics of complex formation and decay based on L{sup 2} methods. In all of these studies, the authors focus on systems that are of interest experimentally, and for which potential energy surfaces based, at least in part, on ab initio calculations are available.

Bowman, J.M. [Emory Univ., Atlanta, GA (United States)

1993-12-01T23:59:59.000Z

415

Glassy dynamics of protein folding  

Science Journals Connector (OSTI)

A coarse-grained model of a random polypeptide chain, with only discrete torsional degrees of freedom and Hookean springs connecting pairs of hydrophobic residues is shown to display stretched exponential relaxation under Metropolis dynamics at low temperatures with the exponent ??1/4, in agreement with the best experimental results. The time dependent correlation functions for fluctuations about the native state, computed in the Gaussian approximation for real proteins, have also been found to have the same functional form. Our results indicate that the energy landscape exhibits universal features over a very large range of energies and is relatively independent of the specific dynamics.

Erkan Tüzel and Ay?e Erzan

2000-02-01T23:59:59.000Z

416

Cluster dynamics transcending chemical dynamics toward nuclear fusion  

Science Journals Connector (OSTI)

...chemical dynamics toward nuclear fusion 10.1073/pnas.0508622103...optimization of table-top dd nuclear fusion driven by CE of deuterium containing...Huizenga J. R. ( 1992 ) Cold Fusion ( Oxford Univ. Press , Oxford...R. H. ( 1960 ) Controlled Thermonuclear Reactions ( Van Nostrand , New...

Andreas Heidenreich; Joshua Jortner; Isidore Last

2006-01-01T23:59:59.000Z

417

398 IEEE TRANSACTIONS ON MAGNETICS, VOL. 42, NO. 3, MARCH 2006 Introducing Dynamic Behavior of Magnetic Materials  

E-Print Network (OSTI)

of Magnetic Materials Into a Model of a Switched Reluctance Motor Drive F. Sixdenier, L. Morel, and J. P, we present the model of an ultrafast switched reluctance motor, in which the control of the power switched reluctance motor (SRM) drive [9], [10] designed by the Labora- toire de genie industriel et

Boyer, Edmond

418

The Dynamics of Syntactic Knowledge  

Science Journals Connector (OSTI)

......Original Articles The Dynamics of Syntactic Knowledge Thomas agotnes Department of Informatics...logical omniscience problem by taking knowledge as primary rather than as defined in...1Introduction The most studied formal logics of knowledge and belief, epistemic and doxastic logics1......

Thomas Ågotnes; Natasha Alechina

2007-02-01T23:59:59.000Z

419

Dynamical friction on satellite galaxies  

E-Print Network (OSTI)

For a rigid model satellite, Chandrasekhar's dynamical friction formula describes the orbital evolution quite accurately, when the Coulomb logarithm is chosen appropriately. However, it is not known if the orbital evolution of a real satellite with the internal degree of freedom can be described by the dynamical friction formula. We performed N-body simulation of the orbital evolution of a self-consistent satellite galaxy within a self-consistent parent galaxy. We found that the orbital decay of the simulated satellite is significantly faster than the estimate from the dynamical friction formula. The main cause of this discrepancy is that the stars stripped out of the satellite are still close to the satellite, and increase the drag force on the satellite through two mechanisms. One is the direct drag force from particles in the trailing tidal arm, a non-axisymmetric force that slows the satellite down. The other is the indirect effect that is caused by the particles remaining close to the satellite after escape. The force from them enhances the wake caused in the parent galaxy by dynamical friction, and this larger wake in turn slows the satellite down more than expected from the contribution of its bound mass. We found these two have comparable effects, and the combined effect can be as large as 20% of the total drag force on the satellite.

Michiko Fujii; Yoko Funato; Junichiro Makino

2005-11-22T23:59:59.000Z

420

LECTURES IN ELEMENTARY FLUID DYNAMICS  

E-Print Network (OSTI)

LECTURES IN ELEMENTARY FLUID DYNAMICS: Physics, Mathematics and Applications J. M. McDonough Departments of Mechanical Engineering and Mathematics University of Kentucky, Lexington, KY 40506-0503 c 1987, 1990, 2002, 2004, 2009 #12;Contents 1 Introduction 1 1.1 Importance of Fluids

McDonough, James M.

Note: This page contains sample records for the topic "ultrafast solvation dynamics" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


421

Knots and dynamics tienne Ghys  

E-Print Network (OSTI)

was the starting point of the (now forgotten) theory of "vortex atoms", trying to explain elementary "atoms-hydrodynamics: the dynamics of electrically conducting fluids (like a plasma). If one assumes that the fluid is perfect and has no resistance (ideal MHD), the magnetic (divergence free) vector field is merely tran

Ghys, Ã?tienne

422

Theory of the dynamics of  

E-Print Network (OSTI)

possible units??) q, the catchability coefficient: ...is defined as the proportion of the total stock over time, we can also keep track of the change in biomass (B), using the same model but substituting B for N: This might represent the dynamics of an unexploited fish stock... To add exploitation onto this

Limburg, Karin E.

423

Dynamical Theory of K Mesons  

Science Journals Connector (OSTI)

Considerations leading to a complete dynamical theory of K particles and hyperons are outlined. The theory exploits several points of analogy between the ? field and the electromagnetic field, and gives a qualitatively satisfactory description of a number of phenomena. In particular, it accounts for the variety of K-particle decay modes, including those exhibiting opposite parity.

Julian Schwinger

1956-11-15T23:59:59.000Z

424

An API for dynamic partial evaluation under DynamoRIO  

E-Print Network (OSTI)

Dynamic optimization systems have available runtime (dynamic) data and can cross more boundaries than traditional static optimization systems in the pursuit of program transformations. However, dynamic optimization systems ...

Leger, Christopher, 1981-

2004-01-01T23:59:59.000Z

425

DLFM library tools for large scale dynamic applications.  

NLE Websites -- All DOE Office Websites (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...

426

SciTech Connect: Hot electron dynamics in graphene  

NLE Websites -- All DOE Office Websites (Extended Search)

ThesisDissertation: Hot electron dynamics in graphene Citation Details In-Document Search Title: Hot electron dynamics in graphene Hot electron dynamics in graphene Graphene, a...

427

Benzene Dimer: Dynamic Structure and Thermodynamics Derived from...  

NLE Websites -- All DOE Office Websites (Extended Search)

Benzene Dimer: Dynamic Structure and Thermodynamics Derived from On-the-Fly ab initio DFT-D Molecular Dynamic Simulations. Benzene Dimer: Dynamic Structure and Thermodynamics...

428

Ion-pairing dynamics of Li{sup +} and SCN{sup -} in dimethylformamide solution: Chemical exchange two-dimensional infrared spectroscopy  

SciTech Connect

Ultrafast two-dimensional infrared (2DIR) spectroscopy has been proven to be an exceptionally useful method to study chemical exchange processes between different vibrational chromophores under thermal equilibria. Here, we present experimental results on the thermal equilibrium ion pairing dynamics of Li{sup +} and SCN{sup -} ions in N,N-dimethylformamide. Li{sup +} and SCN{sup -} ions can form a contact ion pair (CIP). Varying the relative concentration of Li{sup +} in solution, we could control the equilibrium CIP and free SCN{sup -} concentrations. Since the CN stretch frequency of Li-SCN CIP is blue-shifted by about 16 cm{sup -1} from that of free SCN{sup -} ion, the CN stretch IR spectrum is a doublet. The temperature-dependent IR absorption spectra reveal that the CIP formation is an endothermic (0.57 kJ/mol) process and the CIP state has larger entropy by 3.12 J/(K mol) than the free ion states. Since the two ionic configurations are spectrally distinguishable, this salt solution is ideally suited for nonlinear IR spectroscopic investigations to study ion pair association and dissociation dynamics. Using polarization-controlled IR pump-probe methods, we first measured the lifetimes and orientational relaxation times of these two forms of ionic configurations. The vibrational population relaxation times of both the free ion and CIP are about 32 ps. However, the orientational relaxation time of the CIP, which is {approx}47 ps, is significantly longer than that of the free SCN{sup -}, which is {approx}7.7 ps. This clearly indicates that the effective moment of inertia of the CIP is much larger than that of the free SCN{sup -}. Then, using chemical exchange 2DIR spectroscopy and analyzing the diagonal peak and cross-peak amplitude changes with increasing the waiting time, we determined the contact ion pair association and dissociation time constants that are found to be 165 and 190 ps, respectively. The results presented and discussed in this paper are believed to be important, not only because the ion-pairing dynamics is one of the most fundamental physical chemistry problems but also because such molecular ion-ion interactions are of critical importance in understanding Hofmeister effects on protein stability.

Lee, Kyung-Koo; Park, Kwang-Hee; Kwon, Donghyun; Choi, Jun-Ho; Son, Hyewon [Department of Chemistry, Research Institute for Natural Sciences, Korea University, Seoul 136-701 (Korea, Republic of); Park, Sungnam; Cho, Minhaeng [Department of Chemistry, Research Institute for Natural Sciences, Korea University, Seoul 136-701 (Korea, Republic of); Multidimensional Spectroscopy Laboratory, Korea Basic Science Institute, Seoul 136-713 (Korea, Republic of)

2011-02-14T23:59:59.000Z

429

Geophysical Fluid Dynamics Laboratory Presented by  

E-Print Network (OSTI)

Dynamics Laboratory Outline: · Introduction · Software Infrastructure Projects: Completed Current consortium for climate-weather community 3 #12;Geophysical Fluid Dynamics Laboratory Software Infrastructure Projects ­ Completed: · Flexible Modeling System (FMS) · FMS Model: Hybrid programming model Memory

430

Aging Dynamics in Mixed Nanoclay Dispersions  

Science Journals Connector (OSTI)

This chapter investigates the ergodicity breaking and aging dynamics in mixture of colloidal clays, Laponite (L) and Montmorillonite (MMT). The relaxation dynamics has been studied systematically through the l...

Ravi Kumar Pujala

2014-01-01T23:59:59.000Z

431

Archetypal energy landscapes: Dynamical diagnosis Florin Despa  

E-Print Network (OSTI)

Archetypal energy landscapes: Dynamical diagnosis Florin Despa Department of Chemistry, University studies have identified several motifs for potential energy surfaces corresponding to distinct dynamic and thermodynamic properties. The corresponding disconnectivity graphs were identified as ``palm tree,'' ``willow

Berry, R. Stephen

432

Optimization of naïve dynamic binary instrumentation Tools/  

E-Print Network (OSTI)

The proliferation of dynamic program analysis tools has done much to ease the burden of developing complex software. However, creating such tools remains a challenge. Dynamic binary instrumentation frameworks such as ...

Kleckner, Reid (Reid N.)

2011-01-01T23:59:59.000Z

433

Lab experiences for teaching undergraduate dynamics  

E-Print Network (OSTI)

This thesis describes several projects developed to teach undergraduate dynamics and controls. The materials were developed primarily for the class 2.003 Modeling Dynamics and Control I. These include (1) a set of ActivLab ...

Lilienkamp, Katherine A. (Katherine Ann), 1969-

2003-01-01T23:59:59.000Z

434

Dynamic Algorithm for Space Weather Forecasting System  

E-Print Network (OSTI)

We propose to develop a dynamic algorithm that intelligently analyzes existing solar weather data and constructs an increasingly more accurate equation/algorithm for predicting solar weather accurately in real time. This dynamic algorithm analyzes a...

Fischer, Luke D.

2011-08-08T23:59:59.000Z

435

A Multiscale Analysis of Dynamic Wetting  

E-Print Network (OSTI)

Williams, B. C. (2008). Engineering Fluid Mechanics. Wiley,Thermo-Fluid Dynamics: In Materials Science and Engineering.Fluid Dynamics. McGraw-Hill Sci- ence/Engineering/Math, 1st

Minaki, Hiroyuki

2013-01-01T23:59:59.000Z

436

Development of a Dynamic DOE Calibration Model  

Energy.gov (U.S. Department of Energy (DOE))

A dynamic heavy duty diesel engine model was developed. The model can be applied for calibration and control system optimization.

437

Insight Gained from Simplified Dynamic Analysis  

Energy.gov (U.S. Department of Energy (DOE))

Insight Gained from Simplified Dynamic Analysis ... or Everything Old is New Again October 21, 2014 Greg Mertz Consultant

438

Risk-Averse Stochastic Dual Dynamic Programming  

E-Print Network (OSTI)

Feb 27, 2013 ... dynamic programming for hydroelectricity generation, Technical report, Electric Power Opti- mization Centre, University of Auckland, ...

2013-02-27T23:59:59.000Z

439

Dynamic Screening and Thermonuclear Reaction Rates  

E-Print Network (OSTI)

We show that there are no dynamic screening corrections to the Salpeter's enhancement factor in the weak-screening limit.

Andrei V. Gruzinov

1997-02-06T23:59:59.000Z

440

Dynamics of Josephson-junction ladders  

SciTech Connect

We have numerically studied dynamical behaviors of Josephson-junction ladders consisting of [ital N][sub [ital p

Kim, J. (Department of Physics, Basic Science Research Institute, Pohang Institute of Science and Technology, Pohang P.O. Box 125, Kyungbuk 790-600 (Korea, Republic of) Division of Basic Science Research, Research Institute of Industrial Science and Technology, Pohang P.O. Box 135, Kyungbuk 790-600 (Korea, Republic of)); Choe, W.G.; Kim, S. (Department of Physics, Basic Science Research Institute, Pohang Institute of Science and Technology, Pohang P.O. Box 125, Kyungbuk 790-600 (Korea, Republic of)); Lee, H.J. (Department of Physics, Basic Science Research Institute, Pohang Institute of Science and Technology, Pohang P.O. Box 125, Kyungbuk 790-600 (Korea, Republic of) Division of Basic Science Research, Research Institute of Industrial Science and Technology, Pohang P.O. Box 135, Kyungbuk 790-600 (Korea, Republic of))

1994-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "ultrafast solvation dynamics" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


441

Dynamic capabilities in the software process  

Science Journals Connector (OSTI)

Software development is an important dynamic capability of a software-developing organisation. This paper explores product development in general and software development in particular from the viewpoint of the dynamic capabilities research stream ... Keywords: RBV, dynamic capabilities, inductive reasoning, product development, product innovation, resource transformation typology, resource-based view, software business, software development, software engineering, software process

Markus M. Makela; Nilay V. Oza; Jyrki Kontio

2008-12-01T23:59:59.000Z

442

Socio-economic dynamics of biofuel  

E-Print Network (OSTI)

i Socio-economic dynamics of biofuel development in Asia Pacific Christina Schott Jakarta, 2009 #12;ii Socio-economic dynamics of biofuel development in Asia Pacific Socio-economic dynamics of biofuel of many biofuels has turned out to be far from sustainable. The carbon balance often proves to be negative

443

Dynamic Testing of Check Valves William Rahmeyer  

E-Print Network (OSTI)

Dynamic Testing of Check Valves William Rahmeyer Professor of Civil and Environmental Engineering;1 DYNAMIC FLOW TESTING OF CHECK VALVES by William Rahmeyer, Professor of Civil and Environmental Engineering objectives of this paper are: (1) to present a test method by which check valves can be dynamically tested

Rahmeyer, William J.

444

Control algorithms for dynamic attenuators  

SciTech Connect

Purpose: The authors describe algorithms to control dynamic attenuators in CT and compare their performance using simulated scans. Dynamic attenuators are prepatient beam shaping filters that modulate the distribution of x-ray fluence incident on the patient on a view-by-view basis. These attenuators can reduce dose while improving key image quality metrics such as peak or mean variance. In each view, the attenuator presents several degrees of freedom which may be individually adjusted. The total number of degrees of freedom across all views is very large, making many optimization techniques impractical. The authors develop a theory for optimally controlling these attenuators. Special attention is paid to a theoretically perfect attenuator which controls the fluence for each ray individually, but the authors also investigate and compare three other, practical attenuator designs which have been previously proposed: the piecewise-linear attenuator, the translating attenuator, and the double wedge attenuator. Methods: The authors pose and solve the optimization problems of minimizing the mean and peak variance subject to a fixed dose limit. For a perfect attenuator and mean variance minimization, this problem can be solved in simple, closed form. For other attenuator designs, the problem can be decomposed into separate problems for each view to greatly reduce the computational complexity. Peak variance minimization can be approximately solved using iterated, weighted mean variance (WMV) minimization. Also, the authors develop heuristics for the perfect and piecewise-linear attenuators which do not requirea priori knowledge of the patient anatomy. The authors compare these control algorithms on different types of dynamic attenuators using simulated raw data from forward projected DICOM files of a thorax and an abdomen. Results: The translating and double wedge attenuators reduce dose by an average of 30% relative to current techniques (bowtie filter with tube current modulation) without increasing peak variance. The 15-element piecewise-linear dynamic attenuator reduces dose by an average of 42%, and the perfect attenuator reduces dose by an average of 50%. Improvements in peak variance are several times larger than improvements in mean variance. Heuristic control eliminates the need for a prescan. For the piecewise-linear attenuator, the cost of heuristic control is an increase in dose of 9%. The proposed iterated WMV minimization produces results that are within a few percent of the true solution. Conclusions: Dynamic attenuators show potential for significant dose reduction. A wide class of dynamic attenuators can be accurately controlled using the described methods.

Hsieh, Scott S., E-mail: sshsieh@stanford.edu [Department of Radiology, Stanford University, Stanford, California 94305 and Department of Electrical Engineering, Stanford University, Stanford, California 94305 (United States); Pelc, Norbert J. [Department of Radiology, Stanford University, Stanford California 94305 and Department of Bioengineering, Stanford University, Stanford, California 94305 (United States)] [Department of Radiology, Stanford University, Stanford California 94305 and Department of Bioengineering, Stanford University, Stanford, California 94305 (United States)

2014-06-15T23:59:59.000Z

445

THE JOURNAL OF CHEMICAL PHYSICS 139, 175101 (2013) Dynamic neutron scattering from conformational dynamics. I. Theory  

E-Print Network (OSTI)

#12;THE JOURNAL OF CHEMICAL PHYSICS 139, 175101 (2013) Dynamic neutron scattering from, a conformational dynamics theory of dynamical neutron and X-ray scattering is developed, follow- ing our previous spectroscopy (dynamic neutron scattering) probes time correlations on the sub pico- to microsec- ond timescales

446

Dynamic imaging with electron microscopy  

ScienceCinema (OSTI)

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.

Campbell, Geoffrey; McKeown, Joe; Santala, Melissa

2014-05-30T23:59:59.000Z

447

Dynamic imaging with electron microscopy  

SciTech Connect

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.

Campbell, Geoffrey; McKeown, Joe; Santala, Melissa

2014-02-20T23:59:59.000Z

448

Predissociation dynamics of lithium iodide  

E-Print Network (OSTI)

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+ and LiI+ 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=650(20) reciprocal cm. 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.

Schmidt, H; Stienkemeier, F; Bogomolov, A S; Baklanov, A V; Reich, D M; Skomorowski, W; Koch, C P; Mudrich, M

2015-01-01T23:59:59.000Z

449

Unwinding relaxation dynamics of polymers  

E-Print Network (OSTI)

The relaxation dynamics of a polymer wound around a fixed obstacle constitutes a fundamental instance of polymer with twist and torque and it is of relevance also for DNA denaturation dynamics. We investigate it by simulations and Langevin equation analysis. The latter predicts a relaxation time scaling as a power of the polymer length times a logarithmic correction related to the equilibrium fluctuations of the winding angle. The numerical data support this result and show that at short times the winding angle decreases as a power-law. This is also in agreement with the Langevin equation provided a winding-dependent friction is used, suggesting that such reduced description of the system captures the basic features of the problem.

Jean-Charles Walter; Marco Baiesi; Gerard Barkema; Enrico Carlon

2013-01-13T23:59:59.000Z

450

A Reformulation of Newtonian Dynamics  

Science Journals Connector (OSTI)

It is postulated that all dynamical laws must be formulated in terms of variables measured relative to interacting particles. This implies that the two-particle system is the fundamental interaction unit. When this postulate is applied to Newtonian mechanics a radically new conceptual structure is revealed. The two major changes which result are the absence of the law of inertia and a broadening of the space and time invariance to include accelerated observers. Although energy and angular momentum remain conserved in this reformulation the usual linear momentum theorem does not appear. It is further shown that the theory can be expressed in the Lagrangian and Hamiltonian formalisms in a straightforward manner. Finally applications are made to several simple two-body and three-body systems which demonstrate that many-particle interactions can be formulated without reference to the dynamics of a single particle.

C. Gregory Hood

1970-01-01T23:59:59.000Z

451

The dynamics of fragment formation  

SciTech Connect

We demonstrate that in the Quantum Molecular Dynamics model, dynamical correlations can result in the production rate for final state nucleon clusters (and hence composite fragments) being higher than would be expected if statistics and the available phase space were dominant in determining composite formation. An intranuclear cascade or a Boltzmann-Uehling-Uhlenbeck model, combined with a statistical approach in the late stage of the collision to determine composites, provides an equivalent description only under limited conditions of centrality and beam energy. We use data on participant fragment production in Au + Au collisions in the Bevalac`s BOS time projection chamber to map out the parameter space where statistical clustering provides a good description. In particular, we investigate momentum-space densities of fragments up to {sup 4}He as a function of fragment transverse momentum, azimuth relative to the reaction plane, rapidity, multiplicity and beam energy.

Keane, D. [Kent State Univ., OH (United States); EOS Collaboration

1994-09-01T23:59:59.000Z

452

Dynamic load balancing of applications  

DOE Patents (OSTI)

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.

Wheat, Stephen R. (Albuquerque, NM)

1997-01-01T23:59:59.000Z

453

Dynamic response of guyed towers  

E-Print Network (OSTI)

guyed towers. A parametric study was conducted using eigen analysis to determine the effects of consistent mass, geometric stiffness and P-Delta gravity loads. Time domain solutions were obtained by direct integration for motion due to regular Stokes... guyed tower 2 References to guyed tower dynamic analysis 4 Effect of mass formulation on tower natural periods. 5 P-Delta effect on fundamental period. 6 Effect of axial compression on the 1st & 2nd mode. 7 Geometric stiffness effect on natural...

Gillcrist, Mark Christopher

2012-06-07T23:59:59.000Z

454

Turbo Dynamics | Open Energy Information  

Open Energy Info (EERE)

Turbo Dynamics Turbo Dynamics Jump to: navigation, search Name Turbo Dynamics Address 3235 River rd. Place Toledo, Ohio Zip 43614 Sector Biomass, Buildings, Efficiency, Renewable Energy, Services, Solar Product Agriculture; Consulting;Energy audits/weatherization; Engineering/architectural/design;Installation; Maintenance and repair;Manufacturing; Research and development;Retail product sales and distribution;Trainining and education Phone number 419-382-7287 Website http://www.turbodradial.com Coordinates 41.607247°, -83.591719° Loading map... {"minzoom":false,"mappingservice":"googlemaps3","type":"ROADMAP","zoom":14,"types":["ROADMAP","SATELLITE","HYBRID","TERRAIN"],"geoservice":"google","maxzoom":false,"width":"600px","height":"350px","centre":false,"title":"","label":"","icon":"","visitedicon":"","lines":[],"polygons":[],"circles":[],"rectangles":[],"copycoords":false,"static":false,"wmsoverlay":"","layers":[],"controls":["pan","zoom","type","scale","streetview"],"zoomstyle":"DEFAULT","typestyle":"DEFAULT","autoinfowindows":false,"kml":[],"gkml":[],"fusiontables":[],"resizable":false,"tilt":0,"kmlrezoom":false,"poi":true,"imageoverlays":[],"markercluster":false,"searchmarkers":"","locations":[{"text":"","title":"","link":null,"lat":41.607247,"lon":-83.591719,"alt":0,"address":"","icon":"","group":"","inlineLabel":"","visitedicon":""}]}

455

Brownian dynamics without Green's functions  

SciTech Connect

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.

Delong, Steven; Donev, Aleksandar, E-mail: donev@courant.nyu.edu [Courant Institute of Mathematical Sciences, New York University, New York, New York 10012 (United States)] [Courant Institute of Mathematical Sciences, New York University, New York, New York 10012 (United States); Usabiaga, Florencio Balboa; Delgado-Buscalioni, Rafael [Departamento de Física Teórica de la Materia Condensada and Condensed Matter Physics Center (IFIMAC), Univeridad Autónoma de Madrid, Madrid 28049 (Spain)] [Departamento de Física Teórica de la Materia Condensada and Condensed Matter Physics Center (IFIMAC), Univeridad Autónoma de Madrid, Madrid 28049 (Spain); Griffith, Boyce E. [Courant Institute of Mathematical Sciences, New York University, New York, New York 10012 (United States) [Courant Institute of Mathematical Sciences, New York University, New York, New York 10012 (United States); Leon H. Charney Division of Cardiology, Department of Medicine, New York University School of Medicine, New York, New York 10016 (United States)

2014-04-07T23:59:59.000Z

456

Dynamics of evaporative colloidal patterning  

E-Print Network (OSTI)

Drying suspensions often leave behind complex patterns of particulates, as might be seen in the coffee stains on a table. Here we consider the dynamics of periodic band or uniform solid film formation on a vertical plate suspended partially in a drying colloidal solution. Direct observations allow us to visualize the dynamics of the band and film deposition, and the transition in between when the colloidal concentration is varied. A minimal theory of the liquid meniscus motion along the plate reveals the dynamics of the banding and its transition to the filming as a function of the ratio of deposition and evaporation rates. We also provide a complementary multiphase model of colloids dissolved in the liquid, which couples the inhomogeneous evaporation at the evolving meniscus to the fluid and particulate flows and the transition from a dilute suspension to a porous plug. This allows us to determine the concentration dependence of the bandwidth and the deposition rate. Together, our findings allow for the control of drying-induced patterning as a function of the colloidal concentration and evaporation rate.

C. Nadir Kaplan; Ning Wu; Shreyas Mandre; Joanna Aizenberg; L. Mahadevan

2014-12-04T23:59:59.000Z

457

Brownian Dynamics without Green's Functions  

E-Print Network (OSTI)

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.

S. Delong; F. Balboa Usabiaga; R. Delgado-Buscalioni; B. E. Griffith; A. Donev

2014-01-16T23:59:59.000Z

458

Brownian Dynamics Simulation of Protein Solutions: Structural and Dynamical Properties  

SciTech Connect

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.

Mereghetti, Paolo; Gabdoulline, Razif; Wade, Rebecca C.

2010-12-01T23:59:59.000Z

459

Scalar Mesons and Chiral Dynamics  

Science Journals Connector (OSTI)

We discuss scalar mesons properties on the light of chiral dynamics. Considering them as the chiral partners of pseudo?scalar mesons we propose an explanation to their unusual properties based on non?trivial vacuum effects coming from the interplay between spontaneous breaking of chiral symmetry and the violation of UA (1) symmetry by instantons. Including vector mesons as external sources we work out predictions for radiative decays of vector mesons and compare some of them with recent experimental results from high luminosity ? factories.

Mauro Napsuciale

2002-01-01T23:59:59.000Z

460

Scalar Mesons and Chiral Dynamics  

E-Print Network (OSTI)

We discuss scalar mesons properties on the light of chiral dynamics. Considering them as the chiral partners of pseudo-scalar mesons we propose an explanation to their unusual properties based on non-trivial vacuum effects coming from the interplay between spontaneous breaking of chiral symmetry and the violation of $U_A(1)$ symmetry by instantons. Including vector mesons as external sources we work out predictions for radiative decays of vector mesons and compare some of them with recent experimental results from high luminosity $\\Phi$ factories.

Mauro Napsuciale

2002-04-15T23:59:59.000Z

Note: This page contains sample records for the topic "ultrafast solvation dynamics" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


461

Loop shaping of structural dynamics  

E-Print Network (OSTI)

Ratios. . 51 5 Constant Current Tests. 6 Varying Current Tests 75 79 LIST OF FIGURES Figure Page 1 Idealized Multiple-Degree-of Freedom Structure. 2 Induced Matrix Norm. 13 3 System G(s) . 15 4 Singular Values of Displacement Response... in terms of the expected values of stochastic signals. All of these various interpretations make the H?norm useful in engineering applications. 15 w(t) G(s) z(t) Fig. 3. System G(s) 2. 3 Singular Values of Structural Dynamics 2. 3. 1 Displacement...

Kim, Byeong Hwa

1999-01-01T23:59:59.000Z

462

Dynamic Structure Factor of Microemulsions  

Science Journals Connector (OSTI)

The dynamic structure factor G(k,?) is studied in a time-dependent Ginzburg-Landau model for microemulsions in thermal equilibrium by field-theoretic perturbation methods. For small viscosities, the structure factor develops a peak at a nonzero frequency ?, for fixed wavelengths of the order of the typical domain size of oil and water regions. This implies that the intermediate scattering function oscillates in time. We give a simple explanation for these temporal oscillations by considering the flow through a tube with a radius-dependent tension.

G. Gompper and M. Hennes

1994-08-22T23:59:59.000Z

463

Dynamical analysis of highly excited molecular spectra  

SciTech Connect

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.

Kellman, M.E. [Univ. of Oregon, Eugene (United States)

1993-12-01T23:59:59.000Z

464

Dynamic Testing of Gasifier Refractory  

SciTech Connect

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.

Michael D. Mann; Devdutt Shukla; Xi Hong; John P. Hurley

2004-09-27T23:59:59.000Z

465

Radiation in molecular dynamic simulations  

SciTech Connect

Hot dense radiative (HDR) plasmas common to Inertial Confinement Fusion (ICF) and stellar interiors have high temperature (a few hundred eV to tens of keV), high density (tens to hundreds of g/cc) and high pressure (hundreds of Megabars to thousands of Gigabars). Typically, such plasmas undergo collisional, radiative, atomic and possibly thermonuclear processes. In order to describe HDR plasmas, computational physicists in ICF and astrophysics use atomic-scale microphysical models implemented in various simulation codes. Experimental validation of the models used to describe HDR plasmas are difficult to perform. Direct Numerical Simulation (DNS) of the many-body interactions of plasmas is a promising approach to model validation but, previous work either relies on the collisionless approximation or ignores radiation. We present a new numerical simulation technique to address a currently unsolved problem: the extension of molecular dynamics to collisional plasmas including emission and absorption of radiation. The new technique passes a key test: it relaxes to a blackbody spectrum for a plasma in local thermodynamic equilibrium. This new tool also provides a method for assessing the accuracy of energy and momentum exchange models in hot dense plasmas. As an example, we simulate the evolution of non-equilibrium electron, ion, and radiation temperatures for a hydrogen plasma using the new molecular dynamics simulation capability.

Glosli, J; Graziani, F; More, R; Murillo, M; Streitz, F; Surh, M

2008-10-13T23:59:59.000Z

466

Dynamics of magnetic nanoparticle suspensions  

E-Print Network (OSTI)

We study the dynamics of a suspension of magnetic nanoparticles. Their relaxation times are strongly size-dependent. The dominant mode of relaxation is also governed by the size of the particles. As a result the dynamics is greatly altered due to polydispersity in the sample. We study the effect of polydispersity on the response functions. These exhibit significant changes as the parameters characterizing polydispersity are varied. We also provide a procedure to extract the particle size distribution in a polydisperse sample using Cole-Cole plots. Further the presence of attractive interactions causes aggregation of particles leading to the formation of clusters. Repulsive interactions along with thermal disorder not only hinder aggregation, but also introduce the possibility of removal of particles or "fragmentation" from clusters. The competing mechanisms of aggregation and fragmentation yield a distribution of cluster sizes in the steady-state. We attempt to understand the formation of clusters and their distributions using a model incorporating the phenomena of aggregation and fragmentation. Scaling forms for quantities of interest have been obtained. Finally we compare our numerical results with experimental data. These comparisons are satisfactory.

Vanchna Singh; Varsha Banerjee; Manish Sharma

2012-08-20T23:59:59.000Z

467

Pre-equilibrium plasma dynamics  

SciTech Connect

Approaches towards understanding and describing the pre-equilibrium stage of quark-gluon plasma formation in heavy-ion collisions are reviewed. Focus is on a kinetic theory approach to non-equilibrium dynamics, its extension to include the dynamics of color degrees of freedom when applied to the quark-gluon plasma, its quantum field theoretical foundations, and its relationship to both the particle formation stage at the very beginning of the nuclear collision and the hydrodynamic stage at late collision times. The usefulness of this approach to obtain the transport coefficients in the quark-gluon plasma and to derive the collective mode spectrum and damping rates in this phase are discussed. Comments are made on the general difficulty to find appropriated initial conditions to get the kinetic theory started, and a specific model is given that demonstrates that, once given such initial conditions, the system can be followed all the way through into the hydrodynamical regime. 39 refs., 7 figs. (LEW)

Heinz, U.

1986-01-01T23:59:59.000Z

468

Dynamic Drift Compensation for Heliostats  

Science Journals Connector (OSTI)

Abstract In central receiver solar power plants the accuracy of heliostat aiming affects directly the plant efficiency. This accuracy depends on multiple factors, some of which are alignment and operation parameters like: canting, pedestal leveling, elevation and zenith orientations, structural deformation, and clock-date timer accuracy to calculate solar position. All of those factors produce drift of the heliostat concentrated radiation spot. The error parameters differ from heliostat to heliostat in a field, and affect each one in a different manner, depending on their location in the field. Trying to compensate by software for every single error parameter, and for each heliostat is a hard, time consuming, and impractical task. Instead of that, a dynamic drift compensator may be used to fix the problem. This corrector works well for certain period of time, requiring a recalibration whenever the heliostat image shifts beyond the tolerance region. This method requires less effort, resulting in a practical solution to drift correction. This work reports on the implementation of a dynamic drift compensator based on a static third order polynomial function, at the Heliostat Test Field in Hermosillo, Sonora, Mexico. The results are compared to theoretical predictions based on error parameters for one heliostat.

C. Iriarte-Cornejo; C.A. Arancibia-Bulnes; J. Waissman; R.E. Cabanillas; C.A. Estrada

2014-01-01T23:59:59.000Z

469

Dynamically installed anchors for floating offshore structures.  

E-Print Network (OSTI)

??The gradual depletion of shallow water hydrocarbon deposits has forced the offshore oil and gas industry to develop reserves in deeper waters. Dynamically installed anchors… (more)

Richardson, Mark Damian

2008-01-01T23:59:59.000Z

470

Sandia National Laboratories: Computational Fluid Dynamics Simulations...  

NLE Websites -- All DOE Office Websites (Extended Search)

Canal, Yakima Washington Sandia Publishes Five Reports on the Environmental Effects of Wave-Energy Converters Computational Fluid Dynamics Simulations Provide Insight for Rotor...

471

Dynamics in Polymer | ornl.gov  

NLE Websites -- All DOE Office Websites (Extended Search)

Neutron scattering characterizes dynamics in polymer family Agatha Bardoel - December 01, 2012 Interior of BASIS. Research Contact: Christine Gerstl Understanding the interplay...

472

Controlling Complex Systems and Developing Dynamic Technology  

E-Print Network (OSTI)

the power output of steam engines to feed the factories ofas a whole, the governed steam engine becomes a less dynamic

Avizienis, Audrius Victor

2013-01-01T23:59:59.000Z

473

MOLECULAR DYNAMICS SIMULATIONS OF NANOPARTICLE INTERACTIONS.  

E-Print Network (OSTI)

??Molecular dynamics simulations using the Embedded Atom Method were performed to describe the interparticle behavior of two single crystal spherical nickel nanoparticles during compaction based… (more)

Stone, Tonya Williams

2006-01-01T23:59:59.000Z

474

On the Dynamic Stability of Electricity Markets  

E-Print Network (OSTI)

issues affecting market stability. In particular, we establish a control-theoretical frame- work that uses concepts arising in electricity markets, dynamic games, and

2011-02-09T23:59:59.000Z

475

Dynamic Simulators | netl.doe.gov  

NLE Websites -- All DOE Office Websites (Extended Search)

to Develop Dynamic Simulators for Supercritical Pulverized Coal and Natural Gas Combined Cycle Power Plants A screen shot of the new generic supercritical once-through...

476

Accelerated Molecular Dynamics Simulation of Thermal Desorption.  

E-Print Network (OSTI)

??Desorption is a process ubiquitous in phenomena involving surfaces. However, it has rarely been simulated on the molecular level. Molecular dynamics simulation can provide the… (more)

Becker, Kelly

2008-01-01T23:59:59.000Z

477

Molecular dynamics simulation studies of electrolytes andelectrolyte...  

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

Merit Review and Peer Evaluation Meeting, May 18-22, 2009 -- Washington D.C. es40smith.pdf More Documents & Publications Molecular Dynamics Simulation Studies of...

478

Optimization Online - Dynamic Generation of Scenario Trees  

E-Print Network (OSTI)

Sep 3, 2014 ... Abstract: We present new algorithms for the dynamic generation of scenario trees for multistage stochastic optimization. The different methods ...

G. Ch. Pflug

2014-09-03T23:59:59.000Z

479

Dynamic Positioning System as Dynamic Energy Storage on Diesel-Electric Ships  

E-Print Network (OSTI)

1 Dynamic Positioning System as Dynamic Energy Storage on Diesel-Electric Ships Tor A. Johansen in order to implement energy storage in the kinetic and potential energy of the ship motion using the DP in order to relate the dynamic energy storage capacity to the maximum allowed ship position deviation

Johansen, Tor Arne

480

Modeling Dynamics and Exploring Control of a Single-Wheeled Dynamically Stable Mobile  

E-Print Network (OSTI)

Modeling Dynamics and Exploring Control of a Single-Wheeled Dynamically Stable Mobile Robot. It actively balances and moves on a single wheel using closed loop feedback, making it dynamically stable it a good candidate for operating in human environments. Balancing on a ball allows Ballbot to be omni

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481

Bifurcation theory, adaptive dynamics and dynamic energy budget-structured populations of iteroparous species  

Science Journals Connector (OSTI)

...42, 2nd edn. New York, NY: Springer-Verlag...M. 2000 Dynamic energy and mass budgets...112, 3rd edn. New York, NY: Springer-Verlag...Mathematics, vol. 2. New York, NY: Springer-Verlag...dynamics and dynamic energy budget-structured...

2010-01-01T23:59:59.000Z

482

ORNL DAAC for Biogeochemical Dynamics  

NLE Websites -- All DOE Office Websites (Extended Search)

Home Home Welcome about us image About Us Provides detailed information about the ORNL DAAC. projects image About Data Lists the data products available from the ORNL DAAC. access image Get Data Guides you through the steps needed to acquire the data. tools image Data Tools Some tools to help you work with the data. uso image Help Need assistance? Our staff is happy to help. ORNL DAAC The Oak Ridge National Laboratory Distributed Active Archive Center (ORNL DAAC) for biogeochemical dynamics is one of the National Aeronautics and Space Administration (NASA) Earth Observing System Data and Information System (EOSDIS) data centers managed by the Earth Science Data and Information System (ESDIS) Project. The ORNL DAAC archives data produced by NASA's Terrestrial Ecology Program. The DAAC provides data and information

483

Dynamics of assembly production flow  

E-Print Network (OSTI)

Despite recent developments in management theory, maintaining a manufacturing schedule remains difficult because of production delays and fluctuations in demand and supply of materials. The response of manufacturing systems to such disruptions to dynamic behavior has been rarely studied. To capture these responses, we investigate a process that models the assembly of parts into end products. The complete assembly process is represented by a directed tree, where the smallest parts are injected at leaves and the end products are removed at the root. A discrete assembly process, represented by a node on the network, integrates parts, which are then sent to the next downstream node as a single part. The model exhibits some intriguing phenomena, including overstock cascade, phase transition in terms of demand and supply fluctuations, nonmonotonic distribution of stockout in the network, and the formation of a stockout path and stockout chains. Surprisingly, these rich phenomena result from only the nature of distr...

Ezaki, Takahiro; Nishinari, Katsuhiro

2015-01-01T23:59:59.000Z

484

Rubber friction and tire dynamics  

E-Print Network (OSTI)

We propose a simple rubber friction law, which can be used, e.g., in models of tire (and vehicle) dynamics. The friction law is tested by comparing numerical results to the full rubber friction theory (B.N.J. Persson, J. Phys.: Condensed Matter 18, 7789 (2006)). Good agreement is found between the two theories. We describe a two-dimensional (2D) tire model which combines the rubber friction model with a simple mass-spring description of the tire body. The tire model is very flexible and can be used to calculate accurate mu-slip (and the self-aligning torque) curves for braking and cornering or combined motion (e.g., braking during cornering). We present numerical results which illustrate the theory. Simulations of Anti-Blocking System (ABS) braking are performed using two simple control algorithms.

B. N. J. Persson

2010-07-16T23:59:59.000Z

485

Dynamics of strings between walls  

SciTech Connect

Configurations of vortex-strings stretched between or ending on domain walls were previously found to be 1/4 BPS states. Among zero modes of string positions, the center of mass of strings in each region between two adjacent domain walls is shown to be non-normalizable whereas the rests are normalizable. We study dynamics of vortex-strings stretched between separated domain walls by using two methods, the moduli space (geodesic) approximation of full 1/4 BPS states and the charged particle approximation for string endpoints in the wall effective action. In the first method we obtain the effective Lagrangian explicitly and find the 90 degree scattering for head-on collision. In the second method the domain wall effective action is assumed to be U(1){sup N} gauge theory, and we find a good agreement between two methods for well separated strings. This talk is based on the work [1].

Eto, Minoru [INFN, Sezione di Pisa, Largo Pontecorvo, 3, Ed. C, 56127 Pisa (Italy); Fujimori, Toshiaki; Nagashima, Takayuki [Department of Physics, Tokyo Institute of Technology, Tokyo 152-8551 (Japan); Nitta, Muneto [Department of Physics, Keio University, Hiyoshi, Yokohama, Kanagawa 223-8521 (Japan); Ohashi, Keisuke [Department of Applied Mathematics and Theoretical Physics, University of Cambridge, CB3 0WA (United Kingdom); Sakai, Norisuke [Department of Mathematics, Tokyo Woman's Christian University, Tokyo 167-8585 (Japan)

2008-11-23T23:59:59.000Z

486

Dynamical generation of pseudoscalar resonances  

SciTech Connect

We study the interactions between the f{sub 0}(980) and a{sub 0}(980) scalar resonances and the lightest pseudoscalar mesons. We first obtain the elementary interaction amplitudes, or interacting kernels, without including any ad hoc free parameter. This is achieved by using previous results on the nature of the lightest scalar resonances as dynamically generated from the rescattering of S-wave two-meson pairs. Afterwards, the interaction kernels are unitarized and the final S-wave amplitudes result. We find that these interactions are very rich and generate a large amount of pseudoscalar resonances that could be associated with the K(1460), {pi}(1300), {pi}(1800), {eta}(1475), and X(1835). We also consider the exotic channels with isospin 3/2 and 1, the latter having positive G-parity. The former could also be resonant in agreement with a previous prediction.

Albaladejo, M.; Oller, J. A.; Roca, L. [Departamento de Fisica, Universidad de Murcia, E-30071 Murcia (Spain)

2010-11-01T23:59:59.000Z

487

Dynamic RKKY interaction in graphene  

Science Journals Connector (OSTI)

The growing interest in carbon-based spintronics has stimulated a number of recent theoretical studies on the Ruderman-Kittel-Kasuya-Yosida (RKKY) interaction in graphene, based on which the energetically favorable alignment between magnetic moments embedded in this material can be calculated. The general consensus is that the strength of the RKKY interaction in undoped graphene decays as 1/D3 or faster, where D is the separation between magnetic moments. Such an unusually fast decay for a two-dimensional system suggests that the RKKY interaction may be too short ranged to be experimentally observed in graphene. Here we show in a mathematically transparent form that a far more long ranged interaction arises when the magnetic moments are taken out of their equilibrium positions and set in motion. We not only show that this dynamic version of the RKKY interaction in graphene decays far more slowly but also propose how it can be observed with currently available experimental methods.

S. R. Power; F. S. M. Guimarães; A. T. Costa; R. B. Muniz; M. S. Ferreira

2012-05-07T23:59:59.000Z

488

Dynamical Friction on extended perturbers  

E-Print Network (OSTI)

Following a wave-mechanical treatment we calculate the drag force exerted by an infinite homogeneous background of stars on a perturber as this makes its way through the system. We recover Chandrasekhar's classical dynamical friction (DF) law with a modified Coulomb logarithm. We take into account a range of models that encompasses all plausible density distributions for satellite galaxies by considering the DF exerted on a Plummer sphere and a perturber having a Hernquist profile. It is shown that the shape of the perturber affects only the exact form of the Coulomb logarithm. The latter converges on small scales, because encounters of the test and field stars with impact parameters less than the size of the massive perturber become inefficient. We confirm this way earlier results based on the impulse approximation of small angle scatterings.

O. Esquivel; B. Fuchs

2008-04-01T23:59:59.000Z

489

Nonlinear dynamics and plasma transport  

SciTech Connect

This progress report details work done on a program in nonlinear dynamical aspects of plasma turbulence and transport funded by DOE since 1989. This program has been in cooperation with laboratories in theUSSR [now Russia and the Confederation of Independent States (CIS)]. The purpose of this program has been: To promote the utilization of recent pathbreaking developments in nonlinear science in plasma turbulence and transport