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1

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

SciTech Connect (OSTI)

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 (OSTI)

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 (OSTI)

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 Phenomena XIV, pp. 650-654 , Springer, Berlin (2005). 650 Ultrafast Dynamics of Light Transmission  

E-Print Network [OSTI]

of ultrafast pulse propagation through nano-hole arrays reported a 10-fs delay in transmission [6 of ultrafast light propagation through plasmonic nano-crystals using light pulses much shorter than the SPPUltrafast Phenomena XIV, pp. 650-654 , Springer, Berlin (2005). 650 Ultrafast Dynamics of Light

Peinke, Joachim

5

Ultrafast Core-Hole Induced Dynamics in Water  

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

Ultrafast Core-Hole Induced Dynamics in Water Print A thorough understanding of the chemical processes that are initiated when radiation interacts with aqueous systems is essential...

6

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

E-Print Network [OSTI]

Study of the Structure and Dynamics of Solvated Highly27 Chapter 3 Structure and Dynamics of the High Spin Fe 3+66 Chapter 4 Structure and Dynamics of the Hydrated Ca 2+

Bogatko, Stuart A.

2008-01-01T23:59:59.000Z

7

Structural Dynamics of a Catalytic Monolayer Probed by Ultrafast  

E-Print Network [OSTI]

REPORTS Structural Dynamics of a Catalytic Monolayer Probed by Ultrafast 2D IR Vibrational Echoes in solutions. Here, we extend the technique to probing the interfacial dynamics and structure of a silica. The structural dynamics, as reported on by a carbonyl stretch vibration of the surface-bound complex, have

Fayer, Michael D.

8

Control of ultrafast electron dynamics with shaped femtosecond laser pulses: from atoms to solids  

E-Print Network [OSTI]

Control of ultrafast electron dynamics with shaped femtosecond laser pulses: from atoms to solids;1. Introduction In coherent control shaped femtosecond laser pulses are used as a tool to steer the ultrafast focus on advanced control of ultrafast electron dynamics with shaped femtosecond laser pulses

Peinke, Joachim

9

Ultrafast Magnetism Dynamics Measure Using Tabletop Ultrafast EUV Sources  

SciTech Connect (OSTI)

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

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

SciTech Connect (OSTI)

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

11

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.

12

Ultrafast dynamics of excitons in tetracene single crystals  

SciTech Connect (OSTI)

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

13

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

14

Size-dependent ultrafast structural dynamics inside phospholipid vesicle bilayers measured with 2D IR  

E-Print Network [OSTI]

Size-dependent ultrafast structural dynamics inside phospholipid vesicle bilayers measured with 2D 25, 2013) The ultrafast structural dynamics inside the bilayers of dilauroyl- phosphatidylcholine was used as a vibrational probe and provided information on spectral diffusion (structural dynam- ics

Fayer, Michael D.

15

Adaptive all-order dispersion compensation of ultrafast laser pulses using dynamic spectral holography  

E-Print Network [OSTI]

Adaptive all-order dispersion compensation of ultrafast laser pulses using dynamic spectral-1396 Received 14 July 1999; accepted for publication 24 September 1999 The time-varying dispersion of ultrafast laser pulses can be self-adaptively stabilized using real-time dynamic spectral holography

Nolte, David D.

16

Optical Nonlinearities and Ultrafast Carrier Dynamics in Semiconductor Quantum Dots  

SciTech Connect (OSTI)

Low-dimensional semiconductors have attracted great interest due to the potential for tailoring their linear and nonlinear optical properties over a wide-range. Semiconductor nanocrystals (NC's) represent a class of quasi-zero-dimensional objects or quantum dots. Due to quantum cordhement and a large surface-to-volume ratio, the linear and nonlinear optical properties, and the carrier dynamics in NC's are significantly different horn those in bulk materials. napping at surface states can lead to a fast depopulation of quantized states, accompanied by charge separation and generation of local fields which significantly modifies the nonlinear optical response in NC's. 3D carrier confinement also has a drastic effect on the energy relaxation dynamics. In strongly confined NC's, the energy-level spacing can greatly exceed typical phonon energies. This has been expected to significantly inhibit phonon-related mechanisms for energy losses, an effect referred to as a phonon bottleneck. It has been suggested recently that the phonon bottleneck in 3D-confined systems can be removed due to enhanced role of Auger-type interactions. In this paper we report femtosecond (fs) studies of ultrafast optical nonlinearities, and energy relaxation and trap ping dynamics in three types of quantum-dot systems: semiconductor NC/glass composites made by high temperature precipitation, ion-implanted NC's, and colloidal NC'S. Comparison of ultrafast data for different samples allows us to separate effects being intrinsic to quantum dots from those related to lattice imperfections and interface properties.

Klimov, V.; McBranch, D.; Schwarz, C.

1998-08-10T23:59:59.000Z

17

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.

18

Ultrafast Dynamics and Phase Changes in Solids Excited by Femtosecond Laser Pulses  

E-Print Network [OSTI]

Ultrafast Dynamics and Phase Changes in Solids Excited by Femtosecond Laser Pulses A thesis pulse excites 1­20% of the valence electrons. We developed a broadband pump-probe technique to measure femtoseconds. The dielectric function provides more information than ever before on the ultrafast electronic

Mazur, Eric

19

Ultrafast Structural Dynamics Inside Planar Phospholipid Multibilayer Model Cell Membranes Measured with 2D IR  

E-Print Network [OSTI]

Ultrafast Structural Dynamics Inside Planar Phospholipid Multibilayer Model Cell Membranes Measured diffusion caused by the structural dynamics of the membrane from 200 fs to 200 ps as a function structure and an abrupt change in dynamics at 35% cholesterol. The dynamics are independent of cholesterol

Fayer, Michael D.

20

Femtosecond soft x-ray spectroscopy of solvated transition metal complexes: Deciphering the interplay of electronic and structural dynamics  

SciTech Connect (OSTI)

We present the first implementation of femtosecond soft X-ray spectroscopy as an ultrafast direct probe of the excited-state valence orbitals in solution-phase molecules. This method is applied to photoinduced spin crossover of [Fe(tren(py)3)]2+, where the ultrafast spinstate conversion of the metal ion, initiated by metal-to-ligand charge-transfer excitation, is directly measured using the intrinsic spin-state selectivity of the soft X-ray L-edge transitions. Our results provide important experimental data concerning the mechanism of ultrafast spin-state conversion and subsequent electronic and structural dynamics, highlighting the potential of this technique to study ultrafast phenomena in the solution phase.

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

2011-03-09T23:59:59.000Z

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.


21

Ultrafast Structural Dynamics in Combustion Relevant Model Systems  

SciTech Connect (OSTI)

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

22

Dynamics of Functionalized Surface Molecular Monolayers Studied with Ultrafast Infrared Vibrational Spectroscopy  

E-Print Network [OSTI]

Dynamics of Functionalized Surface Molecular Monolayers Studied with Ultrafast Infrared Vibrational by excitation transfer and molecular reorientation. The HDTG experiments show no evidence of anisotropy decay of molecular monolayers depend on the structure and dynamics of the surface-attached molecules. New tools

Fayer, Michael D.

23

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

24

Simultaneous investigation of ultrafast structural dynamics and transient electric field by sub-picosecond electron pulses  

SciTech Connect (OSTI)

The ultrafast structure dynamics and surface transient electric field, which are concurrently induced by laser excited electrons of an aluminum nanofilm, have been investigated simultaneously by the same transmission electron diffraction patterns. These two processes are found to be significantly different and distinguishable by tracing the time dependent changes of electron diffraction and deflection angles, respectively. This study also provides a practical means to evaluate simultaneously the effect of transient electric field during the study of structural dynamics under low pump fluence by transmission ultrafast electron diffraction.

Li, Run-Ze; Zhu, Pengfei; Chen, Long; Chen, Jie, E-mail: jiec@sjtu.edu.cn, E-mail: jzhang1@sjtu.edu.cn; Sheng, Zheng-Ming; Zhang, Jie, E-mail: jiec@sjtu.edu.cn, E-mail: jzhang1@sjtu.edu.cn [Key Laboratory for Laser Plasmas (Ministry of Education) and Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240 (China); Cao, Jianming [Key Laboratory for Laser Plasmas (Ministry of Education) and Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240 (China); Physics Department and National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310 (United States)

2014-05-14T23:59:59.000Z

25

Ultrafast Core-Hole Induced Dynamics in Water  

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

AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr MayAtmosphericNuclear SecurityTensile Strain Switched Ferromagnetism in Layeredof2014 EIA Energy40081AEnergy StorageUltrafastUltrafast

26

Ultrafast time dynamics studies of periodic lattices with free electron laser radiation  

SciTech Connect (OSTI)

It has been proposed that radiation from free electron laser (FEL) at Hamburg (FLASH) can be used for ultrafast time-resolved x-ray diffraction experiments based on the near-infrared (NIR) pump/FEL probe scheme. Here, investigation probing the ultrafast structural dynamics of periodic nano-crystalline organic matter (silver behenate) with such a scheme is reported. Excitation with a femtosecond NIR laser leads to an ultrafast lattice modification which time evolution has been studied through the scattering of vacuum ultraviolet FEL pulses. The found effect last for 6 ps and underpins the possibility for studying nanoperiodic dynamics down to the FEL source time resolution. Furthermore, the possibility of extending the use of silver behenate (AgBh) as a wavelength and temporal calibration tool for experiments with soft x-ray/FEL sources is suggested.

Quevedo, W.; Busse, G.; Hallmann, J.; More, R.; Petri, M.; Rajkovic, I. [Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Goettingen (Germany); Krasniqi, F.; Rudenko, A. [Max Planck Advanced Study Group at CFEL, Notkestrasse 85, 22607 Hamburg (Germany); Tschentscher, T. [European XFEL GmbH, Albert-Einstein-Ring 19, 22671 Hamburg (Germany); Stojanovic, N.; Duesterer, S.; Treusch, R.; Tolkiehn, M. [HASYLAB at DESY, Notkestrasse 85, 22607 Hamburg (Germany); Techert, S. [Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Goettingen (Germany); Max Planck Advanced Study Group at CFEL, Notkestrasse 85, 22607 Hamburg (Germany)

2012-11-01T23:59:59.000Z

27

Ultrafast infrared studies of chemical reaction dynamics in room-temperature liquids  

E-Print Network [OSTI]

ultrafast pulses ..analyses of the ultrafast pulses. (a) A spectral analysis ofExperimentally, an ultrafast UV pulse dissociates a photo

Yang, H.

2011-01-01T23:59:59.000Z

28

Probing Ultrafast Solvation Dynamics with High Repetition-Rate Laser/X-ray  

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

AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr MayAtmosphericNuclear Security Administration the1 - SeptemberMicroneedles for4-16 FORPoints ofProbing Strain-Induced Changes

29

Dynamics of water-alcohol mixtures: Insights from nuclear magnetic resonance, broadband dielectric spectroscopy, and triplet solvation dynamics  

SciTech Connect (OSTI)

We combine {sup 2}H nuclear magnetic resonance (NMR), broadband dielectric spectroscopy (BDS), and triplet solvation dynamics (TSD) to investigate molecular dynamics in glass-forming mixtures of water and propylene glycol in very broad time and temperature ranges. All methods yield consistent results for the ? process of the studied mixtures, which hardly depends on the composition and shows Vogel-Fulcher temperature dependence as well as Cole-Davidson spectral shape. The good agreement between BDS and TDS data reveals that preferential solvation of dye molecules in microheterogeneous mixtures does not play an important role. Below the glass transition temperature T{sub g}, NMR and BDS studies reveal that the ? process of the mixtures shows correlation times, which depend on the water concentration, but exhibit a common temperature dependence, obeying an Arrhenius law with an activation energy of E{sub a} = 0.54? eV, as previously reported for mixtures of water with various molecular species. Detailed comparison of NMR and BDS correlation functions for the ? process unravels that the former decay faster and more stretched than the latter. Moreover, the present NMR data imply that propylene glycol participates in the ? process and, hence, it is not a pure water process, and that the mechanism for molecular dynamics underlying the ? process differs in mixtures of water with small and large molecules.

Sauer, D.; Schuster, B.; Rosenstihl, M.; Schneider, S.; Blochowicz, T.; Stühn, B.; Vogel, M. [Institut für Festkörperphysik, Technische Universität Darmstadt, Hochschulstraße 6, 64289 Darmstadt (Germany)] [Institut für Festkörperphysik, Technische Universität Darmstadt, Hochschulstraße 6, 64289 Darmstadt (Germany); Talluto, V.; Walther, T. [Institut für Angewandte Physik, Technische Universität Darmstadt, Schlossgartenstraße 7, 64289 Darmstadt (Germany)] [Institut für Angewandte Physik, Technische Universität Darmstadt, Schlossgartenstraße 7, 64289 Darmstadt (Germany)

2014-03-21T23:59:59.000Z

30

Non-adiabatic molecular dynamics simulation of ultrafast solar cell electron transfer  

E-Print Network [OSTI]

confinement devices [1­5]. Solar cells of the Graetzel type [6,7] are based on dye sensitized nanocrystalline in solar cells, photocatalysis and photoelectrolysis. The electronic structure of the dye cell; Ultrafast electron transfer; Non-adiabatic molecular dynamics simulation; Dye sensitized titanium

31

Ultrafast Carrier Dynamics in Exfoliated and Functionalized Calcium Niobate Nanosheets in Water and Methanol  

E-Print Network [OSTI]

Ultrafast Carrier Dynamics in Exfoliated and Functionalized Calcium Niobate Nanosheets in Water trapping and recombination processes in suspensions of exfoliated calcium niobate nanosheets derived from in exfoliated [H1-xCa2Nb3O10]x- nanosheets (x ) 0.15-0.20) and APS-functionalized (TBA,H)- Ca2Nb3O10. We

Osterloh, Frank

32

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.

33

Ultrafast Strong-Field Vibrational Dynamics Studied by Femtosecond Extreme-Ultraviolet Transient Absorption Spectroscopy  

E-Print Network [OSTI]

to yield a compressed, ultrafast pulse close to the originalspectral width of the ultrafast optical pulses, delivering

Hosler, Erik Robert

2013-01-01T23:59:59.000Z

34

Structural aspects of the solvation shell of lysine and acetylated lysine: A Car-Parrinello and classical molecular dynamics investigation  

SciTech Connect (OSTI)

Lysine acetylation is a post-translational modification, which modulates the affinity of protein-protein and/or protein-DNA complexes. Its crucial role as a switch in signaling pathways highlights the relevance of charged chemical groups in determining the interactions between water and biomolecules. A great effort has been recently devoted to assess the reliability of classical molecular dynamics simulations in describing the solvation properties of charged moieties. In the spirit of these investigations, we performed classical and Car-Parrinello molecular dynamics simulations on lysine and acetylated-lysine in aqueous solution. A comparative analysis between the two computational schemes is presented with a focus on the first solvation shell of the charged groups. An accurate structural analysis unveils subtle, yet statistically significant, differences which are discussed in connection to the significant electronic density charge transfer occurring between the solute and the surrounding water molecules.

Carnevale, V. [Department of Chemistry, Center for Molecular Modeling, University of Pennsylvania, Philadelphia, Pennsylvania, 19104-6323 (United States); Raugei, S. [International School for Advanced Studies (SISSA) and CNR-INFM Democritos, Via Beirut 2, Trieste I-34014 Italy, Trieste (Italy)

2009-12-14T23:59:59.000Z

35

Ultrafast Core-Hole Induced Dynamics in Water  

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

AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr May JunDatastreamsmmcrcalgovInstrumentsrucLasDelivered energy consumption by sectorlong version) The0 -ITER'sUltrafast Core-Hole Induced

36

Ultrafast Core-Hole Induced Dynamics in Water  

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

AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr May JunDatastreamsmmcrcalgovInstrumentsrucLasDelivered energy consumption by sectorlong version) The0 -ITER'sUltrafast Core-Hole

37

Ultrafast Core-Hole Induced Dynamics in Water  

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

AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr MayAtmosphericNuclear SecurityTensile Strain Switched Ferromagnetism in Layeredof2014 EIA Energy40081AEnergy StorageUltrafast Core-Hole

38

Ultrafast Core-Hole Induced Dynamics in Water  

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

AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr MayAtmosphericNuclear SecurityTensile Strain Switched Ferromagnetism in Layeredof2014 EIA Energy40081AEnergy StorageUltrafast

39

Ultrafast Core-Hole Induced Dynamics in Water  

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

AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr MayAtmosphericNuclear SecurityTensile Strain Switched Ferromagnetism in Layeredof2014 EIA Energy40081AEnergy Storage EnergyUltrafast

40

The solvation of Cl , Br , and I in acetonitrile clusters: Photoelectron spectroscopy and molecular dynamics simulations  

E-Print Network [OSTI]

The solvation of Cl , Br , and I in acetonitrile clusters: Photoelectron spectroscopy and molecular in acetonitrile clusters CH3CN n with n 1­33, 1­40, and 1­55, respectively, taken with 7.9 eV photon energy. Anion simulations of halide­acetonitrile clusters reproduce the measured stabilization energies and generate full

Perera, Lalith

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

Using femtosecond electron pulses as an imaging tool, we can probe ultrafast dynamics by taking snapshots at different time delays. By using femtosecond electron diffraction (FED),  

E-Print Network [OSTI]

Abstract Using femtosecond electron pulses as an imaging tool, we can probe ultrafast dynamics correlation. Additionally, ultrafast electron shadow imaging (UESI) can explore the dynamics of laser induced System The femtosecond "camera" mentioned above is comprised of an amplified femtosecond pulsed laser

Weston, Ken

42

Car–Parrinello molecular dynamics in the DFT + U formalism: Structure and energetics of solvated ferrous and ferric ions  

SciTech Connect (OSTI)

The research described in this product was performed in part in the Environmental Molecular Sciences Laboratory, a national scientific user facility sponsored by the Department of Energy's Office of Biological and Environmental Research and located at Pacific Northwest National Laboratory. We implemented a rotationally-invariant Hubbard U extension to density-functional theory in the Car–Parrinello molecular dynamics framework, with the goal of bringing the accuracy of the DFT + U approach to finite-temperature simulations, especially for liquids or solids containing transition-metal ions. First, we studied the effects on the Hubbard U on the static equilibrium structure of the hexaaqua ferrous and ferric ions, and the inner-sphere reorganization energy for the electron-transfer reaction between aqueous ferrous and ferric ions. It is found that the reorganization energy is increased, mostly as a result of the Fe–O distance elongation in the hexa-aqua ferrous ion. Second, we performed a first-principles molecular dynamics study of the solvation structure of the two aqueous ferrous and ferric ions. The Hubbard term is found to change the Fe–O radial distribution function for the ferrous ion, while having a negligible effect on the aqueous ferric ion. Moreover, the frequencies of vibrations between Fe and oxygen atoms in the first-solvation shell are shown to be unaffected by the Hubbard corrections for both ferrous and ferric ions.

Sit, P H L.; Cococcioni, Matteo; Marzari, Nicola N.

2007-09-01T23:59:59.000Z

43

Structure and energetics of solvated ferrous and ferric ions: Car-Parrinello molecular dynamics in the DFT+U formalism  

E-Print Network [OSTI]

We implemented a rotationally-invariant Hubbard U extension to density-functional theory in the Car-Parrinello molecular dynamics framework, with the goal of bringing the accuracy of the DFT+U approach to finite-temperature simulations, especially for liquids or solids containing transition-metal ions. First, we studied the effects on the Hubbard U on the static equilibrium structure of the hexa-aqua ferrous and ferric ions, and the inner-sphere reorganization energy for the electron-transfer reaction between aqueous ferrous and ferric ions. It is found that the reorganization energy is increased, mostly as a result of the Fe-O distance elongation in the hexa-aqua ferrous ion. Second, we performed a first-principles molecular dynamics study of the solvation structure of the two aqueous ferrous and ferric ions. The Hubbard term is found to change the Fe-O radial distribution function for the ferrous ion, while having a negligible effect on the aqueous ferric ion. Moreover, the frequencies of vibrations between Fe and oxygen atoms in the first-solvation shell are shown to be unaffected by the Hubbard corrections for both ferrous and ferric ions.

P. H. -L. Sit; Matteo Cococcioni; Nicola Marzari

2007-01-12T23:59:59.000Z

44

Broadband electromagnetic response and ultrafast dynamics of few-layer epitaxial graphene  

SciTech Connect (OSTI)

We study the broadband optical conductivity and ultrafast carrier dynamics of epitaxial graphene in the few-layer limit. Equilibrium spectra of nominally buffer, monolayer, and multilayer graphene exhibit significant terahertz and near-infrared absorption, consistent with a model of intra- and interband transitions in a dense Dirac electron plasma. Non-equilibrium terahertz transmission changes after photoexcitation are shown to be dominated by excess hole carriers, with a 1.2-ps mono-exponential decay that refects the minority-carrier recombination time.

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

2009-03-26T23:59:59.000Z

45

Stabilized Ultrafast Pulse Generation and Optical Frequency Combs Techniques  

E-Print Network [OSTI]

Stabilized Ultrafast Pulse Generation and Optical Frequency Combs ­ Techniques and Applications Diodes ­ Review Ultrafast Dynamics ­ Breathing Mode (Dispersion Managed Cavity) · High Pulse Energy to Make Short Pulses - Review Ultrafast Dynamics- - Dispersion Managed (Breathing Mode) MLL #12

Van Stryland, Eric

46

Ultrafast Excited-State Dynamics in the Green Fluorescent Protein Variant S65T/ H148D. 2. Unusual Photophysical Properties  

E-Print Network [OSTI]

Ultrafast Excited-State Dynamics in the Green Fluorescent Protein Variant S65T/ H148D. 2. Unusual, California 94305-5080, and Institute of Molecular Biology and Department of Physics, UniVersity of Oregon of this variant at pH 5.6 by ultrafast fluorescence upconversion spectroscopy. Following excitation at 400 nm

Boxer, Steven G.

47

Evidence for Conical Intersection Dynamics Mediating Ultrafast Singlet Exciton Fission  

E-Print Network [OSTI]

-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... ), which aligns with the ground-state bleach (GSB) peaks in the middle of the spectrum. b Early-time dynamics from panel a. The initial stimulated emission at 700 nm decays to yield triplets with excited state absorption bands at 520 nm and 820 nm, which...

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

2015-01-01T23:59:59.000Z

48

Ultrafast Laser Pulse Control of Exciton Dynamics: A Computational Study on the FMO Ben Bru1ggemann and Volkhard May*  

E-Print Network [OSTI]

Ultrafast Laser Pulse Control of Exciton Dynamics: A Computational Study on the FMO Complex Ben Bru, D-12489 Berlin, Germany ReceiVed: February 4, 2004; In Final Form: May 23, 2004 Femtosecond laser-pulse on the Frenkel exciton model for the bacteriochlorophyll (BChl) Qy-excitations, the laser- pulse-driven exciton

Röder, Beate

49

Ultrafast dynamics of strongly coupled quantum dot-nanocavity systems  

E-Print Network [OSTI]

We investigate the influence of exciton-phonon coupling on the dynamics of a strongly coupled quantum dot-photonic crystal cavity system and explore the effects of this interaction on different schemes for non-classical light generation. By performing time-resolved measurements, we map out the detuning-dependent polariton lifetime and extract the spectrum of the polariton-to-phonon coupling. Photon-blockade experiments are presented for different pulse-length and detuning conditions that are in very good agreement with quantum-optical simulations; we demonstrate that achieving high-fidelity photon blockade requires an intricate understanding of this parameter space. Furthermore, we show that detuned photon blockade, which is more efficient than resonant photon blockade, is also more dramatically affected by phonons. Finally, we achieve coherent control of the polariton states of a strongly coupled system and demonstrate that their efficient coupling to phonons can be exploited for novel concepts in high-fidelity single photon generation.

Kai Müller; Kevin A. Fischer; Armand Rundquist; Constantin Dory; Konstantinos G. Lagoudakis; Tomas Sarmiento; Victoria Borish; Yousif A. Kelaita; Jelena Vu?kovi?

2015-03-18T23:59:59.000Z

50

A microfluidic flow-cell for the study of the ultrafast dynamics of biological systems  

SciTech Connect (OSTI)

The study of biochemical dynamics by ultrafast spectroscopic methods is often restricted by the limited amount of liquid sample available, while the high repetition rate of light sources can induce photodamage. In order to overcome these limitations, we designed a high flux, sub-ml, capillary flow-cell. While the 0.1 mm thin window of the 0.5 mm cross-section capillary ensures an optimal temporal resolution and a steady beam deviation, the cell-pump generates flows up to ?0.35 ml/s that are suitable to pump laser repetition rates up to ?14 kHz, assuming a focal spot-diameter of 100 ?m. In addition, a decantation chamber efficiently removes bubbles and allows, via septum, for the addition of chemicals while preserving the closed atmosphere. The minimal useable amount of sample is ?250 ?l.

Chauvet, Adrien, E-mail: adrien.chauvet@epfl.ch; Chergui, Majed [Ecole Polytechnique Fédérale de Lausanne (EPFL), Laboratoire de Spectroscopie Ultrarapide, ISIC, Faculté des Sciences de Base, Station 6, 1015 Lausanne (Switzerland); Tibiletti, Tania; Caffarri, Stefano [Aix Marseille Université, CNRS, CEA, UMR 7265 Biologie Végétale et Microbiologie Environnementales, 13009 Marseille (France)

2014-10-15T23:59:59.000Z

51

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

52

Coherent lattice and molecular dynamics in ultrafast single-shot spectroscopy  

E-Print Network [OSTI]

This thesis focuses on the development, refinement, and application of dual- echelon single-shot ultrafast spectroscopy to the study of coherent nuclear motion in condensed phase systems. The general principles of the ...

Poulin, Peter Roland, 1973-

2005-01-01T23:59:59.000Z

53

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

SciTech Connect (OSTI)

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

54

Ultrafast Excited-State Dynamics in the Green Fluorescent Protein Variant S65T/ H148D. 1. Mutagenesis and Structural Studies,  

E-Print Network [OSTI]

Articles Ultrafast Excited-State Dynamics in the Green Fluorescent Protein Variant S65T/ H148D. 1 Kanchanawong,# William Childs,# Steven G. Boxer,# and S. James Remington*,§ Institute of Molecular Biology chromophores, respectively. Excitation of either band leads to green emission. In wt-GFP, excitation of band

Boxer, Steven G.

55

Use of Ultrafast Dispersed Pump-Dump-Probe and Pump-Repump-Probe Spectroscopies to Explore the Light-Induced Dynamics of Peridinin in Solution  

E-Print Network [OSTI]

Use of Ultrafast Dispersed Pump-Dump-Probe and Pump-Repump-Probe Spectroscopies to Explore Form: NoVember 14, 2005 Optical pump-induced dynamics of the highly asymmetric carotenoid peridinin in methanol was studied by dispersed pump-probe, pump-dump-probe, and pump-repump-probe transient absorption

van Stokkum, Ivo

56

Characterization and light-induced dynamics of alkanethiol-capped gold nanoparticles supracrystals by small-angle ultrafast electron diffraction  

E-Print Network [OSTI]

Metal nanoparticles (NPs) are promising candidates for applications from electronics to medicine. Their metallic core provides some key properties, e.g. magnetization, plasmonic response or conductivity, with the ligand molecules providing others like solubility, assembly or interaction with biomolecules. Even more properties can be engineered when these NPs are used as building blocks to form supracrystals. The formation of these supracrystals depends upon a complex interplay between many forces, some stemming from the core, some from the ligand. At present, there is no known approach to characterize the local order of ligand molecules in such complex supracrystals or their dynamics, with a spatial resolution ranging from the NPs cores and their ligands, to the larger scale domains arrangement. Here, we develop a methodology based on small-angle ultrafast electron diffraction to characterize different two-dimensional supracrystals of alkanethiol-coated gold nanoparticles with femtosecond time, sub-nanometer ...

Mancini, Giulia Fulvia; Pennacchio, Francesco; Reguera, Javier; Stellacci, Francesco; Carbone, Fabrizio

2015-01-01T23:59:59.000Z

57

A dynamic and ultrafast group delay tuning mechanism in two microcavities side-coupled with a waveguide system  

SciTech Connect (OSTI)

We theoretically propose a dynamic and ultrafast group delay tuning mechanism in two microcavities side-coupled to a waveguide system through external optical pump beams. The optical Kerr effect modulation method is applied to improve tuning rate with response time of subpicoseconds or even femtoseconds. The group delay of an all-optical analog to electromagnetically induced transparency effect can be controlled by tuning either the frequency of photonic crystal microcavities or the propagation phase of line waveguide. Group delay is controlled between 5.88 and 70.98?ps by dynamically tuning resonant frequencies of the microcavities. Alternatively, the group delay is controlled between 1.86 and 12.08?ps by dynamically tuning the propagation phase of line waveguide. All observed schemes are analyzed rigorously through finite-difference time-domain simulations and coupled-mode formalism. Results show a new direction toward microstructure integration optical pulse trapping and all-optical dynamical storage of light devices in optical communication and quantum information processing.

Wang, Boyun; Wang, Tao, E-mail: wangtao@hust.edu.cn; Tang, Jian; Li, Xiaoming; Zhu, Youjiang [Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan 430074 (China)

2014-10-07T23:59:59.000Z

58

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

SciTech Connect (OSTI)

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

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

2012-07-25T23:59:59.000Z

59

Emission dynamics of an expanding ultrafast-laser produced Zn plasma under different ambient pressures  

SciTech Connect (OSTI)

We report time and space resolved spectral measurements of neutral Zn emission from an ultrafast laser produced plasma, generated by the irradiation of a Zn target with laser pulses of 100 femtoseconds duration, carried out in a broad ambient pressure range of 0.05 to 100 Torr. The measurement is done for three different axial positions in the expanding plume. The spectra are rich in neutral Zn (Zn I) emissions at 334.5 nm, 468 nm, 472 nm, 481 nm, and 636 nm, respectively, depicting the characteristic triplet structure of Zn. Fast as well as slow peaks are observed in the time of flight data of 481 nm emission, which arise from recombination and atomic contributions, respectively, occurring at different time scales. Average speeds of the fast atomic species do not change appreciably with ambient pressure. The plasma parameters (electron temperature and number density) are evaluated from the measured optical emission spectra. The rates of ionization and recombination can be enhanced by a double-pulse excitation configuration in which optical energy is coupled to the ultrafast plasma through a delayed laser pulse.

Smijesh, N.; Philip, Reji [Raman Research Institute, C.V. Raman Avenue, Sadashivanagar, Bangalore 560080 (India)] [Raman Research Institute, C.V. Raman Avenue, Sadashivanagar, Bangalore 560080 (India)

2013-09-07T23:59:59.000Z

60

A grazing incidence x-ray streak camera for ultrafast, single-shot measurements  

E-Print Network [OSTI]

provided by UV pulses derived from an ultrafast laser. Dueultrafast dynamics using a single synchrotron x-ray pulse.

Feng, Jun

2010-01-01T23:59:59.000Z

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.


61

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

SciTech Connect (OSTI)

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

62

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

63

Molecular Dynamics Simulations of Solvated Yeast tRNAAsp Pascal Auffinger, Shirley Louise-May, and Eric Westhof  

E-Print Network [OSTI]

of the tRNA molecule. Calculated thermal factors are used to compare the dynamics of the tRNA in solution in the two ends and the "el- bow" of the L-shaped structure, include the 3 -CCA resi- dues of the acceptor

Westhof, Eric

64

Ultrafast dynamics and fragmentation of C60 in intense laser pulses  

E-Print Network [OSTI]

The radiation-induced fragmentation of the C60 fullerene was investigated by the tight-binding electron-ion dynamics simulations. In intense laser field, the breathing vibrational mode is much more strongly excited than the pentagonal-pinch mode. The fragmentation effect was found more remarkable at long wavelength lambda>800 nm rather than the resonant wavelengths due to the internal laser-induced dipole force, and the production ratio of C and C2 rapidly grows with increasing wavelength. By such fragmentation law, C atoms, C2 dimers or large Cn fragments could be selectively obtained by changing the laser wavelength. And the fragmentation of C60 by two laser pulses like the multi-step atomic photoionization was investigated.

Lin, Zheng-Zhe

2014-01-01T23:59:59.000Z

65

Ultrafast probing of ejection dynamics of Rydberg atoms and molecular fragments from electronically excited helium nanodroplets  

SciTech Connect (OSTI)

The ejection dynamics of Rydberg atoms and molecular fragments from electronically excited helium nanodroplets are studied with time-resolved extreme ultraviolet ion imaging spectroscopy. At excitation energies of 23.6 {+-} 0.2 eV, Rydberg atoms in n= 3 and n= 4 states are ejected on different time scales and with significantly different kinetic energy distributions. Specifically, n= 3 Rydberg atoms are ejected with kinetic energies as high as 0.85 eV, but their appearance is delayed by approximately 200 fs. In contrast, n= 4 Rydberg atoms appear within the time resolution of the experiment with considerably lower kinetic energies. Major features in the Rydberg atom kinetic energy distributions for both principal quantum numbers can be described within a simple elastic scattering model of localized perturbed atomic Rydberg atoms that are expelled from the droplet due to their repulsive interaction with the surrounding helium bath. Time-dependent kinetic energy distributions of He{sub 2}{sup +} and He{sub 3}{sup +} ions are presented that support the formation of molecular ions in an indirect droplet ionization process and the ejection of neutral Rydberg dimers on a similar time scale as the n= 3 Rydberg atoms.

Buenermann, Oliver; Kornilov, Oleg; Neumark, Daniel M. [Ultrafast X-ray Science Laboratory, Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Department of Chemistry, University of California, Berkeley, California 94720 (United States); Haxton, Daniel J.; Gessner, Oliver [Ultrafast X-ray Science Laboratory, Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Leone, Stephen R. [Ultrafast X-ray Science Laboratory, Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Department of Chemistry, University of California, Berkeley, California 94720 (United States); Department of Physics, University of California, Berkeley, California 94720 (United States)

2012-12-07T23:59:59.000Z

66

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

67

Ultrafast scanning tunneling microscopy  

SciTech Connect (OSTI)

I have developed an ultrafast scanning tunneling microscope (USTM) based on uniting stroboscopic methods of ultrafast optics and scanned probe microscopy to obtain nanometer spatial resolution and sub-picosecond temporal resolution. USTM increases the achievable time resolution of a STM by more than 6 orders of magnitude; this should enable exploration of mesoscopic and nanometer size systems on time scales corresponding to the period or decay of fundamental excitations. USTM consists of a photoconductive switch with subpicosecond response time in series with the tip of a STM. An optical pulse from a modelocked laser activates the switch to create a gate for the tunneling current, while a second laser pulse on the sample initiates a dynamic process which affects the tunneling current. By sending a large sequence of identical pulse pairs and measuring the average tunnel current as a function of the relative time delay between the pulses in each pair, one can map the time evolution of the surface process. USTM was used to measure the broadband response of the STM`s atomic size tunnel barrier in frequencies from tens to hundreds of GHz. The USTM signal amplitude decays linearly with the tunnel junction conductance, so the spatial resolution of the time-resolved signal is comparable to that of a conventional STM. Geometrical capacitance of the junction does not appear to play an important role in the measurement, but a capacitive effect intimately related to tunneling contributes to the measured signals and may limit the ultimate resolution of the USTM.

Botkin, D.A. [California Univ., Berkeley, CA (United States). Dept. of Physics]|[Lawrence Berkeley Lab., CA (United States)

1995-09-01T23:59:59.000Z

68

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

SciTech Connect (OSTI)

Transient reflectivity (TR) from thin films (6–40?nm thick) of the topological insulator Bi{sub 2}Se{sub 3} revealed ultrafast carrier dynamics, which suggest the existence of both radiative and non-radiative recombination between electrons residing in the upper cone of initially unoccupied high energy Dirac surface states (SS) and holes residing in the lower cone of occupied low energy Dirac SS. The modeling of measured TR traces allowed us to conclude that recombination is induced by the depletion of bulk electrons in films below ?20?nm thick due to the charge captured on the surface defects. We predict that such recombination processes can be observed using time-resolved photoluminescence techniques.

Glinka, Yuri D., E-mail: ydglinka@mail.wvu.edu [Department of Physics and Astronomy, West Virginia University, Morgantown, West Virginia 26506-6315 (United States); Institute of Physics, National Academy of Sciences of Ukraine, Kiev 03028 (Ukraine); Babakiray, Sercan; Johnson, Trent A.; Holcomb, Mikel B.; Lederman, David [Department of Physics and Astronomy, West Virginia University, Morgantown, West Virginia 26506-6315 (United States)

2014-10-27T23:59:59.000Z

69

Models for solvated biomolecular structures  

E-Print Network [OSTI]

the total solvation energy, ?G solv , can be captured in theform (Equation IV.1): ?G solv = i sq i f (r ij ) + f + g (Tterms as in Equation IV.3: ?G solv = ?G polar + ?G apolar (

Cerutti, David

2007-01-01T23:59:59.000Z

70

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

71

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

SciTech Connect (OSTI)

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

Agieienko, Vira N.; Kolesnik, Yaroslav V.; Kalugin, Oleg N., E-mail: onkalugin@gmail.com [Department of Inorganic Chemistry, V. N. Karazin Kharkiv National University, Kharkiv 61022 (Ukraine)

2014-05-21T23:59:59.000Z

72

A Systematic Study of Chloride Ion Solvation in Water using van der Waals Inclusive Hybrid Density Functional Theory  

E-Print Network [OSTI]

In this work, the solvation and electronic structure of the aqueous chloride ion solution was investigated using Density Functional Theory (DFT) based \\textit{ab initio} molecular dynamics (AIMD). From an analysis of radial distribution functions, coordination numbers, and solvation structures, we found that exact exchange ($E_{\\rm xx}$) and non-local van der Waals (vdW) interactions effectively \\textit{weaken} the interactions between the Cl$^-$ ion and the first solvation shell. With a Cl-O coordination number in excellent agreement with experiment, we found that most configurations generated with vdW-inclusive hybrid DFT exhibit 6-fold coordinated distorted trigonal prism structures, which is indicative of a significantly disordered first solvation shell. By performing a series of band structure calculations on configurations generated from AIMD simulations with varying DFT potentials, we found that the solvated ion orbital energy levels (unlike the band structure of liquid water) strongly depend on the un...

Bankura, Arindam; DiStasio, Robert A; Swartz, Charles W; Klein, Michael L; Wu, Xifan

2015-01-01T23:59:59.000Z

73

Linking Ion Solvation and Lithium Battery Electrolyte Properties...  

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

Linking Ion Solvation and Lithium Battery Electrolyte Properties Linking Ion Solvation and Lithium Battery Electrolyte Properties 2010 DOE Vehicle Technologies and Hydrogen...

74

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

Broader source: Energy.gov (indexed) [DOE]

New Polymer Architectures for Imidazole Solvating groups, Anion Mobility and Flexibility New Polymer Architectures for Imidazole Solvating groups, Anion Mobility and Flexibility...

75

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

SciTech Connect (OSTI)

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

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

2014-09-21T23:59:59.000Z

76

Ultrafast Spectroscopy of Correlated Electron Systems  

E-Print Network [OSTI]

full, non-zero bandwidth of an ultrafast pulse with itself.amplifier delivers ultrafast pulses of 45 fs at a repetitionthe “rectification” of an ultrafast optical pulse will have

Schmid, Benjamin Andrew

2009-01-01T23:59:59.000Z

77

Ultrafast dynamics of a near-solid-density layer in an intense femtosecond laser-excited plasma  

SciTech Connect (OSTI)

We report on the picosecond dynamics of a near-solid-density plasma generated by an intense, infrared (??=?800?nm) femtosecond laser using time-resolved pump-probe Doppler spectrometry. An initial red-shift is observed in the reflected third harmonic (??=?266?nm) probe pulse, which gets blue-shifted at longer probe-delays. A combination of particle-in-cell and radiation-hydrodynamics modelling is performed to model the pump laser interaction with the solid target. The results are post-processed to predict the Doppler shift. An excellent agreement is found between the results of such modelling and the experiment. The modelling suggests that the initial inward motion of the critical surface observed in the experiment is due to the passage of a shock-wave-like disturbance, launched by the pump interaction, propagating into the target. Furthermore, in order to achieve the best possible fit to the experimental data, it was necessary to incorporate the effects of bulk ion-acceleration resulting from the electrostatic field set up by the expulsion of electrons from the laser envelope. We also present results of time-resolved pump-probe reflectometry, which are corroborated with the spectrometry results using a 1-D reflectivity model.

Adak, Amitava; Chatterjee, Gourab; Kumar Singh, Prashant; Lad, Amit D.; Brijesh, P.; Kumar, G. Ravindra, E-mail: grk@tifr.res.in [Tata Institute of Fundamental Research, Dr. Homi Bhabha Road, Colaba, Mumbai 400005 (India); Blackman, David R. [York Plasma Institute, University of York, Heslington, York YO10 5DQ (United Kingdom); Robinson, A. P. L. [Central Laser Facility, Rutherford-Appleton Laboratory, Chilton, Didcot OX10 0QX (United Kingdom); Pasley, John [York Plasma Institute, University of York, Heslington, York YO10 5DQ (United Kingdom); Central Laser Facility, Rutherford-Appleton Laboratory, Chilton, Didcot OX10 0QX (United Kingdom)

2014-06-15T23:59:59.000Z

78

Plasmonic enhanced ultrafast switch.  

SciTech Connect (OSTI)

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

79

Ptychographic ultrafast pulse reconstruction  

E-Print Network [OSTI]

We demonstrate a new ultrafast pulse reconstruction modality which is somewhat reminiscent of frequency resolved optical gating but uses a modified setup and a conceptually different reconstruction algorithm that is derived from ptychography. Even though it is a second order correlation scheme it shows no time ambiguity. Moreover, the number of spectra to record is considerably smaller than in most other related schemes which, together with a robust algorithm, leads to extremely fast convergence of the reconstruction.

Spangenberg, D; Brügmann, M H; Feurer, T

2014-01-01T23:59:59.000Z

80

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 (OSTI)

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

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.


81

Lithium Ion Solvation: Amine and Unsaturated Hydrocarbon Solvates of Lithium Hexamethyldisilazide (LiHMDS)  

E-Print Network [OSTI]

Lithium Ion Solvation: Amine and Unsaturated Hydrocarbon Solvates of Lithium Hexamethyldisilazide, and 13C NMR spectroscopic studies of 6Li-15N labeled lithium hexamethyldisilazide ([6Li,15N]- Li ligand structure and lithium amide aggregation state is a complex and sensitive function of amine alkyl

Collum, David B.

82

Femtosecond laser studies of ultrafast intramolecular processes  

SciTech Connect (OSTI)

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

83

Ultrafast optical parametric processes in photonic crystal fibers: fundamentals and applications  

E-Print Network [OSTI]

of ultrafast optical pulses . . . . . . . . .copropagating ultrafast optical pulses”, Appl. Phys. Lett.Additionally, the ultrafast pump pulses can experience

Gu, Chenji

2012-01-01T23:59:59.000Z

84

Ultrafast Transformations in Superionic Nanocrystals  

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

AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr May JunDatastreamsmmcrcalgovInstrumentsrucLasDelivered energy consumption by sectorlong version) The0 -ITER'sUltrafastUltrafastUltrafast

85

Ultrafast Transformations in Superionic Nanocrystals  

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

AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr MayAtmosphericNuclear SecurityTensile Strain Switched Ferromagnetism in Layeredof2014 EIA Energy40081AEnergyUltrafastUltrafastUltrafast

86

Ultrafast studies of organometallic photochemistry: the mechanism of carbon-hydrogen bond activation in solution  

E-Print Network [OSTI]

watts [2]. These "ultrafast pulses" can be used to resolveof the directions that ultrafast pulse research has taken inand a separate ultrafast visible pulse to detect ultrafast

Broomberg, Steven E.

2010-01-01T23:59:59.000Z

87

Ultrafast Transformations in Superionic Nanocrystals  

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

The research team looked at copper sulfide nanodiscs (10 nm in diameter) using ultrafast x-ray pump-probe techniques. The samples were photoexcited with 400-nm laser...

88

Ultrafast optics For optics and photonics course,  

E-Print Network [OSTI]

ultrafast and ultrashort generally describe pulses of widths in the nanosecond to femtosecond, or shorterUltrafast optics For optics and photonics course, Spring 2012 By :Alireza Moheghi Ultrafast optics, regimes. · Interest in ultrashort optical pulses began with the invention of the laser, · Ultrashort

Palffy-Muhoray, Peter

89

High-Pulse-Energy Ultrafast Laser for  

E-Print Network [OSTI]

High-Pulse-Energy Ultrafast Laser for Spectroscopy & Micromachining PROBLEM THIS TECHNOLOGY SOLVES. In addition to the OPO, a custom designed ultrafast pump source, provides high pulse energy (.res.hw.ac.uk Professor Derryck Reid (Principal Investigator) www.ultrafast.hw.ac.uk BENEFITS & APPLICATIONS: · High pulse

Painter, Kevin

90

Unraveling shock-induced chemistry using ultrafast lasers  

SciTech Connect (OSTI)

The exquisite time synchronicity between shock and diagnostics needed to unravel chemical events occurring in picoseconds has been achieved using a shaped ultrafast laser pulse to both drive the shocks and interrogate the sample via a multiplicity of optical diagnostics. The shaped laser drive pulse can produce well-controlled shock states of sub-ns duration with sub-10 ps risetimes, sufficient for investigation offast reactions or phase transformations in a thin layer with picosecond time resolution. The shock state is characterized using ultrafast dynamic ellipsometry (UDE) in either planar or Gaussian spatial geometries, the latter allowing measurements of the equation of state of materials at a range of stresses in a single laser pulse. Time-resolved processes in materials are being interrogated using UDE, ultrafast infrared absorption, ultrafast UV/visible absorption, and femtosecond stimulated Raman spectroscopy. Using these tools we showed that chemistry in an energetic thin film starts only after an induction time of a few tens of ps, an observation that allows differentiation between proposed shock-induced reaction mechanisms. These tools are presently being applied to a variety of energetic and reactive sample systems, from nitromethane and carbon disulfide, to microengineered interfaces in tunable energetic mixtures. Recent results will be presented, and future trends outlined.

Moore, David Steven [Los Alamos National Laboratory

2010-12-06T23:59:59.000Z

91

Ultrafast X-Ray Coherent Control  

SciTech Connect (OSTI)

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

Reis, David

2009-05-01T23:59:59.000Z

92

Ultrafast scanning probe microscopy  

DOE Patents [OSTI]

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

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

1995-01-01T23:59:59.000Z

93

Ultrafast scanning probe microscopy  

DOE Patents [OSTI]

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

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

1995-05-16T23:59:59.000Z

94

Ultrafast gas switching experiments  

SciTech Connect (OSTI)

We describe recent experiments which studied the physics of ultrafast gas breakdown under the extreme overvoltages which occur when a high pressure gas switch is pulse charged to hundreds of kV in 1 ns or less. The highly overvolted peaking gaps produce powerful electromagnetic pulses with risetimes < 100 ps which can be used for ultrawideband radar systems, particle accelerators, laser drivers, bioelectromagnetic studies, electromagnetic effects testing, and for basic studies of gas breakdown physics. We have produced and accurately measured pulses with 50 to 100 ps risetimes to peak levels of 75 to 160 kV at pulse repetition frequencies (PRF) to I kHz. A unique gas switch was developed to hold off hundreds of kV with parasitic inductance less than I nH. An advanced diagnostic system using Fourier compensation was developed to measure single-shot risetimes below 35 ps. The complete apparatus is described and wave forms are presented. The measured data are compared with a theoretical model which predicts key features including dependence on gas species and pressure. We have applied this technology to practical systems driving ultrawideband radiating antennas and bounded wave simulators. For example, we have developed a thyristor/pulse transformer based system using a highly overvolted cable switch. This pulser driving a Sandia- designed TEM cell, provides an ultra wideband impulse with < 200 ps risetime to the test object at a PRF > 1 kHz at > 100 kV/m E field.

Frost, C.A.; Martin, T.H.; Patterson, P.E.; Rinehart, L.F.; Rohwein, G.J.; Roose, L.D.; Aurand, J.F.; Buttram, M.T.

1996-11-01T23:59:59.000Z

95

Spectral Noise Correlations of an Ultrafast Frequency Comb  

E-Print Network [OSTI]

Cavity-based noise detection schemes are combined with ultrafast pulse shaping as a means to diagnose the spectral correlations of both the amplitude and phase noise of an ultrafast frequency comb. The comb is divided into ten spectral regions, and the distribution of noise as well as the correlations between all pairs of spectral regions are measured against the quantum limit. These correlations are then represented in the form of classical noise matrices, which furnish a complete description of the underlying comb dynamics. Their eigendecomposition reveals a set of theoretically predicted, decoupled noise modes that govern the dynamics of the comb. Finally, the matrices contain the information necessary to deduce macroscopic noise properties of the comb.

Roman Schmeissner; Jonathan Roslund; Claude Fabre; Nicolas Treps

2014-10-16T23:59:59.000Z

96

Ultrafast Transformations in Superionic Nanocrystals  

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

AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr May JunDatastreamsmmcrcalgovInstrumentsrucLasDelivered energy consumption by sectorlong version) The0 -ITER'sUltrafastUltrafast

97

Ultrafast Transformations in Superionic Nanocrystals  

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

AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr MayAtmosphericNuclear SecurityTensile Strain Switched Ferromagnetism in Layeredof2014 EIA Energy40081AEnergyUltrafastUltrafast

98

A Systematic Study of Chloride Ion Solvation in Water using van der Waals Inclusive Hybrid Density Functional Theory  

E-Print Network [OSTI]

In this work, the solvation and electronic structure of the aqueous chloride ion solution was investigated using Density Functional Theory (DFT) based \\textit{ab initio} molecular dynamics (AIMD). From an analysis of radial distribution functions, coordination numbers, and solvation structures, we found that exact exchange ($E_{\\rm xx}$) and non-local van der Waals (vdW) interactions effectively \\textit{weaken} the interactions between the Cl$^-$ ion and the first solvation shell. With a Cl-O coordination number in excellent agreement with experiment, we found that most configurations generated with vdW-inclusive hybrid DFT exhibit 6-fold coordinated distorted trigonal prism structures, which is indicative of a significantly disordered first solvation shell. By performing a series of band structure calculations on configurations generated from AIMD simulations with varying DFT potentials, we found that the solvated ion orbital energy levels (unlike the band structure of liquid water) strongly depend on the underlying molecular structures. In addition, these orbital energy levels were also significantly affected by the DFT functional employed for the electronic structure; as the fraction of $E_{\\rm xx}$ was increased, the gap between the highest occupied molecular orbital of Cl$^-$ and the valence band maximum of liquid water steadily increased towards the experimental value.

Arindam Bankura; Biswajit Santra; Robert A. DiStasio Jr.; Charles W. Swartz; Michael L. Klein; Xifan Wu

2015-03-25T23:59:59.000Z

99

Ultrafast optical pulse shaping: A tutorial review Andrew M. Weiner  

E-Print Network [OSTI]

Ultrafast optical pulse shaping: A tutorial review Andrew M. Weiner Purdue University, School 2011 Keywords: Ultrafast optics Pulse shaping Femtosecond optics Coherent control Optical signal programmable reshapingof ultrafast pulses, or generation of arbitrary optical waveforms, according to user

Purdue University

100

Ultrafast Switching of Coherent Electronic Excitation: Great Promise for Reaction Control  

E-Print Network [OSTI]

With the advent of femtosecond laser pulses the temporal aspect of the interplay of light and molecular dynamics pulses [4] are the suitable tools to exert microscopic control on molecular dynamics at the quantum levelUltrafast Switching of Coherent Electronic Excitation: Great Promise for Reaction Control

Peinke, Joachim

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

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

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

Data Science Modeling and Simulation Multimodal Imaging MAUI: Modeling, Analysis, and Ultrafast Imaging MAUI: Modeling, Analysis, and Ultrafast Imaging Project Goals...

102

Ultrafast charge localization in a stripe-phase nickelate  

SciTech Connect (OSTI)

Self-organized electronically-ordered phases are a recurring feature in correlated materials, resulting in e.g. fluctuating charge stripes whose role in high-Tc superconductivity is under debate. However, the relevant cause-effect relations between real-space charge correlations and low-energy excitations remain hidden in time-averaged studies. Here, we reveal ultrafast charge localization and lattice vibrational coupling as dynamical precursors of stripe formation in the model compound La1.75Sr0.25NiO4, using ultrafast and equilibrium mid-infrared spectroscopy. The opening of a pseudogap at a crossover temperature T* far above long-range stripe formation establishes the onset of electronic localization which is accompanied by an enhanced Fano asymmetry of Ni-O stretch vibrations. Ultrafast excitation triggers a sub-picosecond dynamics exposing the synchronous modulation of electron-phonon coupling and charge localization. These results illuminate the role of localization in forming the pseudogap in nickelates, opening a path to understanding this mysterious phase in a broad class of complex oxides.

Coslovich, Giacomo; Huber, Bernhard; Lee, Wei-Sheng; Sasagawa, Takao; Hussain, Zahid; Bechtel, Hans A.; Martin, Michael C.; Shen, Zhi-Xun; W. Schoenlein, Robert; A. Kaindl, Robert

2013-08-30T23:59:59.000Z

103

Lithium Hexamethyldisilazide: A View of Lithium Ion Solvation  

E-Print Network [OSTI]

Lithium Hexamethyldisilazide: A View of Lithium Ion Solvation through a Glass-Bottom Boat BRETT L and reactivities, we were drawn to lithium hexamethyldisilazide (LiHMDS; (Me3Si)2NLi) by its promi- nence principles of lithium ion coordination chemistry.2 Understanding how solvation influences organolithium

Collum, David B.

104

Lithium Diisopropylamide Solvated by Hexamethylphosphoramide: Substrate-Dependent  

E-Print Network [OSTI]

Lithium Diisopropylamide Solvated by Hexamethylphosphoramide: Substrate-Dependent Mechanisms-1301 Received February 9, 2006; E-mail: dbc6@cornell.edu Abstract: Lithium diisopropylamide of lithium-ion solvation at a molecular level of resolution.5 Our interest in HMPA stems from studies

Collum, David B.

105

Classical density functional theory to tackle solvation in molecular liquids  

E-Print Network [OSTI]

We present a brief review of the classical density functional theory of atomic and molecular fluids. We focus on the application of the theory to the determination of the solvation properties of arbitrary molecular solutes in arbitrary molecular solvent. This includes the prediction of the solvation free energies, as well as the characterization of the microscopic, three-dimensional solvent structure.

Jeanmairet, Guillaume; Sergiievskyi, Volodymyr; Borgis, Daniel

2015-01-01T23:59:59.000Z

106

Photoelectron spectroscopy of solvated electrons in alcohol and acetonitrile microjets  

E-Print Network [OSTI]

Photoelectron spectroscopy of solvated electrons in alcohol and acetonitrile microjets Alexander T in methanol, ethanol, and acetonitrile microjets are reported. Solvated electrons are generated. Two features are observed in acetonitrile at 2.61 Ã? 0.11 eV and 3.67 Ã? 0.15 eV, attributed

Neumark, Daniel M.

107

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.

108

Delayed Ultrafast X-ray Auger Probing (DUXAP) of Nucleobase Ultraviolet Photoprotection  

E-Print Network [OSTI]

We present a new method for ultrafast spectroscopy of molecular photoexcited dynamics. The technique uses a pair of femtosecond pulses: a photoexcitation pulse initiating excited state dynamics followed by a soft x-ray (SXR) probe pulse that core ionizes certain atoms inside the molecule. We observe the Auger decay of the core hole as a function of delay between the photoexcitation and SXR pulses. The core hole decay is particularly sensitive to the local valence electrons near the core and shows new types of propensity rules, compared to dipole selection rules in SXR absorption or emission spectroscopy. We apply the delayed ultrafast x-ray Auger probing (DUXAP) method to the specific problem of nucleobase photoprotection to demonstrate its potential. The ultraviolet photoexcited \\pi\\pi* states of nucleobases are prone to chemical reactions with neighboring bases. To avoid this, the single molecules funnel the \\pi\\pi* population to lower lying electronic states on an ultrafast timescale under violation of the...

McFarland, B K; Miyabe, S; Tarantelli, F; Aguilar, A; Berrah, N; Bostedt, C; Bozek, J; Bucksbaum, P H; Castagna, J C; Coffee, R; Cryan, J; Fang, L; Feifel, R; Gaffney, K; Glownia, J; Martinez, T; Mucke, M; Murphy, B; Natan, A; Osipov, T; Petrovic, V; Schorb, S; Schultz, Th; Spector, L; Swiggers, M; Tenney, I; Wang, S; White, W; White, J; Gühr, M

2013-01-01T23:59:59.000Z

109

Estimating ProteinLigand Binding Free Energy: Atomic Solvation Parameters for Partition Coefficient and  

E-Print Network [OSTI]

on the assumption that the overall solvation free energy is the sum of all atomic solvation contributions: Gs iAi (1Estimating Protein­Ligand Binding Free Energy: Atomic Solvation Parameters for Partition Coefficient and Solvation Free Energy Calculation Jianfeng Pei,1,2 Qi Wang,1,2 Jiaju Zhou,3 and Luhua Lai1

Luhua, Lai

110

Femtosecond pulse imaging: ultrafast optical oscilloscope  

E-Print Network [OSTI]

Femtosecond pulse imaging: ultrafast optical oscilloscope P. C. Sun, Y. T. Mazurenko,* and Y as well as our ability to detect the shape of the ul- trashort pulses that can be seen as an ultrafast 12, 1996 A nonlinear optical processor that is capable of real-time conversion of a femtosecond pulse

Fainman, Yeshaiahu

111

Impact system for ultrafast synchrotron experiments  

SciTech Connect (OSTI)

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

Jensen, B. J.; Owens, C. T.; Ramos, K. J.; Yeager, J. D.; Saavedra, R. A.; Luo, S. N.; Hooks, D. E. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Iverson, A. J. [National Security Technologies, Los Alamos, New Mexico 87544 (United States); Fezzaa, K. [Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439 (United States)

2013-01-15T23:59:59.000Z

112

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.

113

Ultrafast Material Science Probed Using Coherent X-ray Pulses from High-Harmonic  

E-Print Network [OSTI]

Chapter 7 Ultrafast Material Science Probed Using Coherent X-ray Pulses from High science have made it possible to generate x-ray pulses at the femto- and attosecond frontiers using either-ray pulses paves the way for a completely new generation of experiments that can capture the coupled dynamics

Aeschlimann, Martin

114

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.

115

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

116

A grazing incidence x-ray streak camera for ultrafast, single-shot measurements  

SciTech Connect (OSTI)

An ultrafast x-ray streak camera has been realized using a grazing incidence reflection photocathode. X-rays are incident on a gold photocathode at a grazing angle of 20 degree and photoemitted electrons are focused by a large aperture magnetic solenoid lens. The streak camera has high quantum efficiency, 600fs temporal resolution, and 6mm imaging length in the spectral direction. Its single shot capability eliminates temporal smearing due to sweep jitter, and allows recording of the ultrafast dynamics of samples that undergo non-reversible changes.

Feng, Jun; Engelhorn, K.; Cho, B.I.; Lee, H.J.; Greaves, M.; Weber, C.P.; Falcone, R.W.; Padmore, H. A.; Heimann, P.A.

2010-02-18T23:59:59.000Z

117

Ultrafast Transformations in Superionic Nanocrystals  

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

AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr MayAtmosphericNuclear SecurityTensile Strain Switched Ferromagnetism in Layeredof2014 EIAUltrafast Transformations in SuperionicUltrafast

118

Ionic strength independence of charge distributions in solvation of biomolecules  

SciTech Connect (OSTI)

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

Virtanen, J. J. [Department of Chemistry, University of Chicago, Chicago, Illinois 60637 (United States); James Franck Institute, University of Chicago, Chicago, Illinois 60637 (United States); Sosnick, T. R. [Department of Biochemistry and Molecular Biology, Institute for Biophysical Dynamics, University of Chicago, Chicago, Illinois 60637 (United States); Computation Institute, University of Chicago, Chicago, Illinois 60637 (United States); Freed, K. F. [Department of Chemistry, University of Chicago, Chicago, Illinois 60637 (United States); James Franck Institute, University of Chicago, Chicago, Illinois 60637 (United States); Computation Institute, University of Chicago, Chicago, Illinois 60637 (United States)

2014-12-14T23:59:59.000Z

119

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

SciTech Connect (OSTI)

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

120

Ultrafast infrared studies of complex ligand rearrangements in solution  

SciTech Connect (OSTI)

The complete description of a chemical reaction in solution depends upon an understanding of the reactive molecule as well as its interactions with the surrounding solvent molecules. Using ultrafast infrared spectroscopy it is possible to observe both the solute-solvent interactions and the rearrangement steps which determine the overall course of a chemical reaction. The topics addressed in these studies focus on reaction mechanisms which require the rearrangement of complex ligands and the spectroscopic techniques necessary for the determination of these mechanisms. Ligand rearrangement is studied by considering two different reaction mechanisms for which the rearrangement of a complex ligand constitutes the most important step of the reaction. The first system concerns the rearrangement of a cyclopentadienyl ring as the response of an organometallic complex to a loss of electron density. This mechanism, commonly referred to as ''ring slip'', is frequently cited to explain reaction mechanisms. However, the ring slipped intermediate is too short-lived to be observed using conventional methods. Using a combination of ultrafast infrared spectroscopy and electronic structure calculations it has been shown that the intermediate exists, but does not form an eighteen-electron intermediate as suggested by traditional molecular orbital models. The second example examines the initial steps of alkyne polymerization. Group 6 (Cr, Mo, W) pentacarbonyl species are generated photolytically and used to catalyze the polymerization of unsaturated hydrocarbons through a series of coordination and rearrangement steps. Observing this reaction on the femto- to millisecond timescale indicates that the initial coordination of an alkyne solvent molecule to the metal center results in a stable intermediate that does not rearrange to form the polymer precursor. This suggests that polymerization requires the dissociation of additional carbonyl ligands before rearrangement can occur. Overall, this research demonstrates the importance of examining reaction dynamics on the ultrafast timescale. In the case of both ring slip and alkyne polymerization, early time dynamics have been invaluable in understanding the exact reaction mechanisms which show important differences from previously accepted models.

Payne, Christine K.

2003-05-31T23:59:59.000Z

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.


121

Ultrafast Spectroscopy of Warm Dense Matter  

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

a plasma. Therefore, to probe a warm dense state undergoing a nonreversible process, an ultrafast technique faster than the ALS pulse duration (70 ps) and a single-shot...

122

Ultrafast Optical Pulses: Synthesis and Applications  

E-Print Network [OSTI]

This dissertation is devoted to ultrafast waveform synthesis using coherent Raman sidebands with the assistance of pulse shapers based on acousto-optic programmable dispersive ?lter (AOPDF) or deformable mirror (DM). Ultrashort optical science has...

Wang, Kai

2013-12-11T23:59:59.000Z

123

An ultrafast carbon nanotube terahertz polarisation modulator  

SciTech Connect (OSTI)

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

124

A coupled RISM/MD or MC simulation methodology for solvation free energies  

E-Print Network [OSTI]

A coupled RISM/MD or MC simulation methodology for solvation free energies Holly Freedman, Thanh N September 2003 Published online: 24 October 2003 Abstract We propose a new computational methodology methods for determination of solvation free energies. We employ the RISM formulation of solvation free

Truong, Thanh N.

125

Nanoscience on the Timescale of Electrons Ultrafast Spectroscopy of Nanomaterials  

E-Print Network [OSTI]

Nanoscience on the Timescale of Electrons Ultrafast Spectroscopy of Nanomaterials Pat Kambhampati with it??? ·How does it actually work??? #12;Nanoscience on the Ultrafast Timescale Pat Kambhampati, Mc? #12;Nanoscience on the Ultrafast Timescale Pat Kambhampati, McGill Chemistry Nanomaterial based

Kambhampati, Patanjali

126

Broadband laser cooling of trapped atoms with ultrafast pulses  

E-Print Network [OSTI]

Broadband laser cooling of trapped atoms with ultrafast pulses B. B. Blinov,* R. N. Kohn, Jr., M. J ions in an rf trap using ultrafast pulses from a mode-locked laser. The temperature of a single ion On the other hand, an ultrafast laser whose pulse is a few picoseconds long will naturally have a bandwidth

Blinov, Boris

127

Ultrafast x-rays: radiographing magnetism Project overview  

E-Print Network [OSTI]

, head of the ultrafast magnetism group. Stanford PULSE is a worldwide renowned centre for ultrafast1 Ultrafast x-rays: radiographing magnetism Project overview The main purpose of the proposed, it is now possible to achieve x-ray pulses that are a few femtoseconds long and that are focused within

Haviland, David

128

SISGR: Linking Ion Solvation and Lithium Battery Electrolyte Properties  

SciTech Connect (OSTI)

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

129

Studies of cosolvent systems in supercritical ethane using solvated electrons.  

SciTech Connect (OSTI)

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

130

Li+ solvation in pure, binary and ternary mixtures of organic carbonate electrolytes  

E-Print Network [OSTI]

Classical molecular dynamics (MD) simulations and quantum chemical density functional theory (DFT) calculations have been employed in the present study to investigate the solvation of lithium cations in pure organic carbonate solvents (ethylene carbonate (EC), propylene carbonate (PC) and dimethyl carbonate (DMC)) and their binary (EC-DMC, 1:1 molar composition) and ternary (EC-DMC-PC, 1:1:3 molar composition) mixtures. The results obtained by both methods indicate that the formation of complexes with four solvent molecules around Li+, exhibiting a strong local tetrahedral order, is the most favorable. However, the molecular dynamics simulations have revealed the existence of significant structural heterogeneities, extending up to a length scale which is more than five times the size of the first coordination shell radius. Due to these significant structural fluctuations in the bulk liquid phases, the use of larger size clusters in DFT calculations has been suggested. Contrary to the findings of the DFT calcu...

Skarmoutsos, Ioannis; Vetere, Valentina; Mossa, Stefano

2014-01-01T23:59:59.000Z

131

Two-Color Ultrafast Photoexcited Scanning Tunneling Microscopy  

SciTech Connect (OSTI)

We report on two-color two-photon photoexcitation of a metal surface driven by ultrafast laser pulses and detected with a scanning tunneling microscope (STM) tip as a proximate anode. Results are presented for two cases: (i) where the tip is retracted from the surface far enough to prohibit tunneling, and (ii) where the tip is within tunneling range of the surface. A delay-modulation technique is implemented to isolate the two-color photoemission from concurrent one-color two-photon photoemission and provide subpicosecond time-resolved detection. When applied with the tip in tunneling range, this approach effectively isolates the two-photon photoexcited current signal from the conventional tunneling current and enables subpicosecond time-resolved detection of the photoexcited surface electrons. The advantage of the two-color approach is highlighted by comparison with the one-color case where optical interference causes thermal modulation of the STM tip length, resulting in tunneling current modulations that are orders of magnitude larger than the current due to photoexcitation of surface electrons. By completely eliminating this interference, and thereby avoiding thermal modulation of the STM tip length, the two-color approach represents an important step toward the ultimate goal of simultaneous subnanometer and subpicosecond measurements of surface electron dynamics by ultrafast-laser-excited STM.

Camillone, N.; Dolocan, A.; Acharya, D.P.; Zahl, P.; Sutter, P.

2011-05-26T23:59:59.000Z

132

Atomic Resolution Coherent Diffractive Imaging and Ultrafast Science  

SciTech Connect (OSTI)

A major scientific challenge is determining the 3-D atomic structure of small nanostructures, including single molecules. Coherent diffractive imaging (CDI) is a promising approach. Recent progress has demonstrated coherent diffraction patterns can be recorded from individual nanostructures and phased to reconstruct their structure. However, overcoming the dose limit imposed by radiation damage is a major obstacle toward the full potential of CDI. One approach is to use ultrafast x-ray or electron pulses. In electron diffraction, amplitudes recorded in a diffraction pattern are unperturbed by lens aberrations, defocus, and other microscope resolution-limiting factors. Sub-A signals are available beyond the information limit of direct imaging. Significant contrast improvement is obtained compared to high-resolution electron micrographs. progress has also been made in developing time-resolved electron diffraction and imaging for the study of ultrafast dynamic processes in materials. This talk will cover these crosscutting issues and the convergence of electron and x-ray diffraction techniques toward structure determination of single molecules.

Zuo, Jian-min (University of Illinois) [University of Illinois

2011-01-12T23:59:59.000Z

133

A compact streak camera for 150 fs time resolved measurement of bright pulses in ultrafast electron diffraction  

SciTech Connect (OSTI)

We have developed a compact streak camera suitable for measuring the duration of highly charged subrelativistic femtosecond electron bunches with an energy bandwidth in the order of 0.1%, as frequently used in ultrafast electron diffraction (UED) experiments for the investigation of ultrafast structural dynamics. The device operates in accumulation mode with 50 fs shot-to-shot timing jitter, and at a 30 keV electron energy, the full width at half maximum temporal resolution is 150 fs. Measured durations of pulses from our UED gun agree well with the predictions from the detailed charged particle trajectory simulations.

Kassier, G. H.; Haupt, K.; Erasmus, N.; Rohwer, E. G.; Bergmann, H. M. von; Schwoerer, H. [Laser Research Institute, University of Stellenbosch, Private Bag X1, 7602 Matieland (South Africa); Coelho, S. M. M.; Auret, F. D. [Department of Physics, University of Pretoria, Pretoria 0002 (South Africa)

2010-10-15T23:59:59.000Z

134

Ultrafast Spectroscopy of Warm Dense Matter  

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

AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr MayAtmosphericNuclear SecurityTensile Strain Switched Ferromagnetism in Layeredof2014 EIA Energy40081AEnergyUltrafast LaserUltrafast

135

Ultrafast Spectroscopy of Warm Dense Matter  

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

AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr MayAtmosphericNuclear SecurityTensile Strain Switched Ferromagnetism in Layeredof2014 EIA Energy40081AEnergyUltrafastUltrafast Spectroscopy

136

PURDUE UNIVERSITY ULTRAFAST OPTICS & OPTICAL FIBER COMMUNICATIONS LABORATORY Photonic RF Waveform Synthesis,  

E-Print Network [OSTI]

PURDUE UNIVERSITY ULTRAFAST OPTICS & OPTICAL FIBER COMMUNICATIONS LABORATORY Photonic RF Waveform, Shijun Xiao Funding from ARO, DARPA, and NSF #12;PURDUE UNIVERSITY ULTRAFAST OPTICS & OPTICAL FIBER performance (spectral engineering, dispersion compensation) #12;PURDUE UNIVERSITY ULTRAFAST OPTICS & OPTICAL

Purdue University

137

PURDUE UNIVERSITY ULTRAFAST OPTICS AND OPTICAL FIBER COMMUNICATIONS LABORATORY Femtosecond Pulse  

E-Print Network [OSTI]

as new pulse sequence processing functionalities. #12;PURDUE UNIVERSITY ULTRAFAST OPTICS AND OPTICAL UNIVERSITY ULTRAFAST OPTICS AND OPTICAL FIBER COMMUNICATIONS LABORATORY CLEO 2002 One Guide ­ One PulsePURDUE UNIVERSITY ULTRAFAST OPTICS AND OPTICAL FIBER COMMUNICATIONS LABORATORY CLEO 2002

Purdue University

138

Adaptive feedback control of ultrafast semiconductor nonlinearities J. Kunde,a)  

E-Print Network [OSTI]

that adaptive feedback optical pulse shaping can be used to control ultrafast semiconductor nonlinearities insight into the interaction of semiconduc- tors and ultrafast optical pulses. Specifically, we develop spectroscopy. More- over, the optimized pulse shape can substantially enhance ultrafast semiconductor

Keller, Ursula

139

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

140

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...

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

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

142

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

SciTech Connect (OSTI)

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

143

Structural Interactions within Lithium Salt Solvates: Cyclic Carbonates and Esters  

SciTech Connect (OSTI)

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

144

Attosecond timing the ultrafast charge-transfer process in atomic collisions  

SciTech Connect (OSTI)

By solving the three-dimensional, time-dependent Schroedinger equation, we have demonstrated that the ultrafast charge-transfer process in ion-atom collisions can be mapped out with attosecond extreme uv (xuv) pulses. During the dynamic-charge transfer from the target atom to the projectile ion, the electron coherently populates the two sites of both nuclei, which can be viewed as a 'short-lived' molecular state. A probing attosecond xuv pulse can instantly unleash the delocalized electron from such a ''transient molecule,'' so that the resulting photoelectron may exhibit a ''double-slit'' interference. On the contrary, either reduced or no photoelectron interference will occur if the attosecond xuv pulse strikes well before or after the collision. Therefore, by monitoring the photoelectron interference visibility, one can precisely time the ultrafast charge-transfer process in atomic collisions with time-delayed attosecond xuv pulses.

Hu, S. X. [Laboratory for Laser Energetics, University of Rochester, 250 East River Road, Rochester, New York 14623 (United States)

2011-04-15T23:59:59.000Z

145

Communication: Barium ions and helium nanodroplets: Solvation and desolvation  

SciTech Connect (OSTI)

The solvation of Ba{sup +} ions created by the photoionization of barium atoms located on the surface of helium nanodroplets has been investigated. The excitation spectra corresponding to the 6p {sup 2}P{sub 1/2} Leftwards-Arrow 6s {sup 2}S{sub 1/2} and 6p {sup 2}P{sub 3/2} Leftwards-Arrow 6s {sup 2}S{sub 1/2} transitions of Ba{sup +} are found to be identical to those recorded in bulk He II [H. J. Reyher, H. Bauer, C. Huber, R. Mayer, A. Schafer, and A. Winnacker, Phys. Lett. A 115, 238 (1986)], indicating that the ions formed at the surface of the helium droplets become fully solvated by the helium. Time-of-flight mass spectra suggest that following the excitation of the solvated Ba{sup +} ions, these are being ejected from the helium droplets either as bare Ba{sup +} ions or as small Ba{sup +}He{sub n} (n < 20) complexes.

Zhang Xiaohang; Drabbels, Marcel [Laboratoire de Chimie Physique Moleculaire, Swiss Federal Institute of Technology Lausanne (EPFL), CH-1015 Lausanne (Switzerland)

2012-08-07T23:59:59.000Z

146

Ultrafast Diagnostics for Electron Beams from Laser Plasma Accelerators  

E-Print Network [OSTI]

Laser, Plasma, Accelerator, Diagnostic PACS: 52.25.0s,Leemans, "Charge Diagnostics for Laser Plasma Accelerators,"Ultrafast Diagnostics for Electron Beams from Laser Plasma

Matlis, N. H.

2011-01-01T23:59:59.000Z

147

Suppression of Magnetic State Decoherence Using Ultrafast Optical Pulses  

E-Print Network [OSTI]

It is shown that the magnetic state decoherence produced by collisions in a thermal vapor can be suppressed by the application of a train of ultrafast optical pulses.

C. Search; P. R. Berman

2000-03-01T23:59:59.000Z

148

Ultrafast charge localization in a stripe-phase nickelate  

E-Print Network [OSTI]

21 . The ability of ultrafast optical pulses to suppress theultrafast response of the mid-IR conductivity to femtosecond optical excitation. Pump pulses

Coslovich, Giacomo

2013-01-01T23:59:59.000Z

149

Dielectric Boundary Force in Biomolecular Solvation  

E-Print Network [OSTI]

for Theoretical Biological Physics UC San Diego Funding: NIH and NSF Applied Mathematics and Analysis Seminar vs. Implicit Molecular dynamics simulations Statistical Mechanics P(X, Y ) = P0e-U(X,Y )/kBT U(X, Y dielectric x Qi i w m =80 =1 w m Free-energy functional Gtotal[] = P Vol (m) + 0 (1 - 2H) dS + w w UvdW d

Li, Bo

150

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 (OSTI)

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

151

Ultrafast Pulse Shaping Approaches to Quantum Computing  

E-Print Network [OSTI]

Quantum computing exploits the quantum-mechanical nature of matter to exist in multiple possible states simultaneously. This new approach promises to revolutionize the present form of computing. As an approach to quantum computing, we discuss ultrafast laser pulse shaping, in particular, the acousto-optic modulator based Fourier-Transform pulse-shaper, which has the ability to modulate tunable high power ultrafast laser pulses. We show that optical pulse shaping is an attractive route to quantum computing since shaped pulses can be transmitted over optical hardware and the same infrastructure can be used for computation and optical information transfer. We also address the problem of extending coherence-times for optically induced processes.

Debabrata Goswami

2003-12-24T23:59:59.000Z

152

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

153

Ultrafast Spectroscopy of Warm Dense Matter  

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

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154

Technical Report Ultrafast X-ray Science at the Sub-Picosecond Pulse Source  

E-Print Network [OSTI]

1 Technical Report Ultrafast X-ray Science at the Sub-Picosecond Pulse Source Kelly J. Gaffney ultrafast phenomena. These techniques involve excitation of a sample with an ultrafast laser pump pulse, USA The ultrafast, high brightness x-ray free electron laser (XFEL) sources of the future have

Wechsler, Risa H.

155

Controlled Coherent Excitations in a Single Cadmium Ion with an Ultrafast Laser  

E-Print Network [OSTI]

of ultrafast pulses in a Ramsey interferometer. This ultrafast coupling is vital in a scheme for generationControlled Coherent Excitations in a Single Cadmium Ion with an Ultrafast Laser by Rudolph Nicolas: Controlled Coherent Excitations in a Single Cadmium Ion with an Ultrafast Laser written by R. N. Kohn Jr. has

Monroe, Christopher

156

Ultrafast X-ray Diffraction Theory Jianshu Cao* and Kent R. Wilson  

E-Print Network [OSTI]

notablely using ultrafast optical pump-probe pulses. Unfortunately, except for a few favorable cases of a sample is initiated by an ultrafast optical laser pulse and then probed by an ultrafast X-ray pulse initiated by the optical pump pulse in real time and real space.9-11 From a simple viewpoint, ultrafast X

Cao, Jianshu

157

Ultrafast extended x-ray absorption fine structure ,,EXAFS...--theoretical considerations  

E-Print Network [OSTI]

13­20 to generate ultrafast x-ray pulses, however, the prospect of ultrafast EXAFS seems encouragingUltrafast extended x-ray absorption fine structure ,,EXAFS...--theoretical considerations Frank L by the recent experimental demonstration of ultrafast x-ray absorption spectroscopy, we present a framework

Cao, Jianshu

158

DIRECT SPACE-TO-TIME PULSE SHAPING FOR ULTRAFAST OPTICAL  

E-Print Network [OSTI]

DIRECT SPACE-TO-TIME PULSE SHAPING FOR ULTRAFAST OPTICAL WAVEFORM GENERATION A Thesis Submitted ago. To the students, past and present, post-docs, and visitors of the Ultrafast Optics & Optical me what it is that I love about this work. The experimental optical pulse train generation devices

Purdue University

159

Ultrafast lasers in the femtosecond regime: generation, amplification  

E-Print Network [OSTI]

Ultrafast lasers in the femtosecond regime: generation, amplification and measurement Pedro can be explored. Ultrafast elec- tromagnetic fields are one of those tools, as they allow the probing is divided in two parts one that deals with the generation and amplification of ultrashort pulses the second

160

Information processing with longitudinal spectral decomposition of ultrafast pulses  

E-Print Network [OSTI]

Information processing with longitudinal spectral decomposition of ultrafast pulses Robert E of waveforms depending on whether their frequency response is or is not known a priori. Ultrafast pulses prove synthesis and detection relying on longitudinal spectral decomposition of subpicosecond optical pulses

Fainman, Yeshaiahu

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,
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161

Generalized model for ultrafast laser induced electron emission from a metal tip  

SciTech Connect (OSTI)

In this paper, we will present a brief review of the recently developed non-equilibrium heating and time dependent tunneling model to study the dynamic processes in using an ultrafast laser to induce electron emission from a metallic tip ranging from the multiphoton to the optical tunneling regime. Due to the short time scale of the ultrafast laser pulse, the lattice is found to be in a non-equilibrium condition and a single temperature model is no longer valid. The ultrafast laser heating enhances the electron emission through both the multiphoton and optical tunneling processes rather than over-barrier emission due to thermal heating. The paper is focused on the methodology of how these two effects (non-equilibrium heating and time-dependent tunneling) are combined in a self-consistent model. The model shows a smooth transition of the emitted charge as a function of laser field, ranging from the multiphoton emission regime at low laser field to the optical tunneling regime at high laser field. The paper will conclude with some discussion of future work.

Ang, L. K. [Singapore University of Technology and Design, Singapore 138682 (Singapore) [Singapore University of Technology and Design, Singapore 138682 (Singapore); School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore 639798 (Singapore); Pant, M. [Singapore University of Technology and Design, Singapore 138682 (Singapore)] [Singapore University of Technology and Design, Singapore 138682 (Singapore)

2013-05-15T23:59:59.000Z

162

Computing Relative Free Energies of Solvation Using Single Reference Thermodynamic Integration Augmented  

E-Print Network [OSTI]

Computing Relative Free Energies of Solvation Using Single Reference Thermodynamic Integration relative transformation free energies in a series of molecules with respect to a single reference state of the SR-TI variant is demonstrated in calculations of relative solvation free energies for a series

163

Dielectric Boundary Force in Molecular Solvation with the PoissonBoltzmann Free Energy: A Shape  

E-Print Network [OSTI]

Dielectric Boundary Force in Molecular Solvation with the Poisson­Boltzmann Free Energy: A Shape boundary force acting on such a boundary is the negative first variation of the elec- trostatic free energy [17,18,35,43,44]. Such a predefined interface is used to compute the solvation free energy as the sum

Li, Bo

164

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

165

High Resolution, Ultrafast SFG Vibrational Spectroscopy | EMSL  

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

AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr May JunDatastreamsmmcrcalgovInstrumentsruc DocumentationP-SeriesFlickr FlickrGuidedCH2M HILLAdministration |BasicResolution, Ultrafast

166

Ultrafast Laser Facility | Photosynthetic Antenna Research Center  

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

AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr MayAtmosphericNuclear SecurityTensile Strain Switched Ferromagnetism in Layeredof2014 EIA Energy40081AEnergyUltrafast Laser Facility

167

Ultrafast Spectroscopy of Warm Dense Matter  

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

AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr MayAtmosphericNuclear SecurityTensile Strain Switched Ferromagnetism in Layeredof2014 EIA Energy40081AEnergyUltrafast Laser

168

Ultrafast Spectroscopy of Warm Dense Matter  

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

AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr MayAtmosphericNuclear SecurityTensile Strain Switched Ferromagnetism in Layeredof2014 EIA Energy40081AEnergyUltrafast

169

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

SciTech Connect (OSTI)

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

170

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

SciTech Connect (OSTI)

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

171

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

172

Applications of Ultrafast Terahertz Pulses for Intra-Excitonic Spectroscopy of Quasi-2D Electron-Hole Gases  

E-Print Network [OSTI]

Applications of Ultrafast Terahertz Pulses for Intra-the utilization of ultrafast terahertz (THz) pulses for theUltrafast Terahertz” 250-kHz Ti:Sapphire Regenerative Amplifier System Pulse

Kaindl, Robert A.; Carnahan, Marc A.; Hagele, Daniel; Chemla, D.S.

2006-01-01T23:59:59.000Z

173

Techniques for synchronization of X-Ray pulses to the pump laser in an ultrafast X-Ray facility  

E-Print Network [OSTI]

synchronization of ultrafast x-ray pulses produced in theAccurate timing of ultrafast x-ray probe pulses emitted fromOF X-RAY PULSES TO THE PUMP LASER IN AN ULTRAFAST X-RAY

Corlett, J.N.; Doolittle, L.; Schoenlein, R.; Staples, J.; Wilcox, R.; Zholents, A.

2003-01-01T23:59:59.000Z

174

Synchronization of x-ray pulses to the pump laser in an ultrafast x-ray facility  

E-Print Network [OSTI]

Accurate timing of ultrafast x-ray probe pulses emitted fromOF X-RAY PULSES TO THE PUMP LASER IN AN ULTRAFAST X-RAY

Corlett, J.N.; Barry, W.; Byrd, J.M.; Schoenlein, R.; Zholents, A.

2002-01-01T23:59:59.000Z

175

Biological Water Dynamics and Entropy: A Biophysical Origin of Cancer and Other Diseases  

E-Print Network [OSTI]

This paper postulates that water structure is altered by biomolecules as well as by disease-enabling entities such as certain solvated ions, and in turn water dynamics and structure affect the function of biomolecular ...

Davidson, Robert

176

Space charge effects in ultrafast electron diffraction and imaging  

SciTech Connect (OSTI)

Understanding space charge effects is central for the development of high-brightness ultrafast electron diffraction and microscopy techniques for imaging material transformation with atomic scale detail at the fs to ps timescales. We present methods and results for direct ultrafast photoelectron beam characterization employing a shadow projection imaging technique to investigate the generation of ultrafast, non-uniform, intense photoelectron pulses in a dc photo-gun geometry. Combined with N-particle simulations and an analytical Gaussian model, we elucidate three essential space-charge-led features: the pulse lengthening following a power-law scaling, the broadening of the initial energy distribution, and the virtual cathode threshold. The impacts of these space charge effects on the performance of the next generation high-brightness ultrafast electron diffraction and imaging systems are evaluated.

Tao Zhensheng; Zhang He; Duxbury, P. M.; Berz, Martin; Ruan, Chong-Yu [Physics and Astronomy Department, Michigan State University, East Lansing, Michigan 48824-2320 (United States)

2012-02-15T23:59:59.000Z

177

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

178

High-performance laser processing using manipulated ultrafast laser pulses  

SciTech Connect (OSTI)

We employ manipulated ultrafast laser pulses to realize microprocessing with high-performance. Efficient microwelding of glass substrates by irradiation by a double-pulse train of ultrafast laser pulses is demonstrated. The bonding strength of two photostructurable glass substrates welded by double-pulse irradiation was evaluated to be 22.9 MPa, which is approximately 22% greater than that of a sample prepared by conventional irradiation by a single pulse train. Additionally, the fabrication of hollow microfluidic channels with a circular cross-sectional shape embedded in fused silica is realized by spatiotemporally focusing the ultrafast laser beam. We show both theoretically and experimentally that the spatiotemporal focusing of ultrafast laser beam allows for the creation of a three-dimensionally symmetric spherical peak intensity distribution at the focal spot.

Sugioka, Koji; Cheng Ya; Xu Zhizhan; Hanada, Yasutaka; Midorikawa, Katsumi [RIKEN - Advanced Science Institute, Wako, Saitama 351-0198 (Japan); State Key Laboratory of High Field Laser Physics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences (China); RIKEN - Advanced Science Institute, Wako, Saitama 351-0198 (Japan)

2012-07-30T23:59:59.000Z

179

Controlling ultrafast currents by the non-linear photogalvanic effect  

E-Print Network [OSTI]

We theoretically investigate the effect of broken inversion symmetry on the generation and control of ultrafast currents in a transparent dielectric (SiO2) by strong femto-second optical laser pulses. Ab-initio simulations based on time-dependent density functional theory predict ultrafast DC currents that can be viewed as a non-linear photogalvanic effect. Most surprisingly, the direction of the current undergoes a sudden reversal above a critical threshold value of laser intensity I_c ~ 3.8*10^13 W/cm2. We trace this switching to the transition from non-linear polarization currents to the tunneling excitation regime. We demonstrate control of the ultrafast currents by the time delay between two laser pulses. We find the ultrafast current control by the non-linear photogalvanic effect to be remarkably robust and insensitive to laser-pulse shape and carrier-envelope phase.

Georg Wachter; Shunsuke A. Sato; Christoph Lemell; Xiao-Min Tong; Kazuhiro Yabana; Joachim Burgdörfer

2015-03-20T23:59:59.000Z

180

Solvation Free Energies of Alanine Peptides: The Effect of Flexibility  

SciTech Connect (OSTI)

The electrostatic (?Gel), cavity-formation (?Gvdw), and total (?G) solvation free energies for 10 alanine peptides ranging in length (n) from 1 to 10 monomers were calculated. The free energies were computed both with xed, extended conformations of the peptides and again for some of the peptides without constraints. The solvation free energies, ?Gel, ?Gvdw, and ?G, were found to be linear in n, with the slopes of the best-fit lines being gamma_el, gamma_vdw, and gamma, respectively. Both gamma_el and gamma were negative for fixed and flexible peptides, and gamma_vdw was negative for fixed peptides. That gamma_vdw was negative was surprising, as experimental data on alkanes, theoretical models, and MD computations on small molecules and model systems generally suggest that gamma_vdw should be positive. A negative gamma_vdw seemingly contradicts the notion that ?Gvdw drives the initial collapse of the protein when it folds by favoring conformations with small surface areas, but when we computed ?Gvdw for the flexible peptides, thereby allowing the peptides to assume natural ensembles of more compact conformations, gamma-vdw was positive. Because most proteins do not assume extended conformations, a ?Gvdw that increases with increasing surface area may be typical for globular proteins. An alternative hypothesis is that the collapse is driven by intramolecular interactions. We show that the intramolecular van der Waal's interaction energy is more favorable for the flexible than for the extended peptides, seemingly favoring this hypothesis, but the large fluctuations in this energy may make attributing the collapse of the peptide to this intramolecular energy difficult.

Kokubo, Hironori; Harris, Robert C.; Asthagiri, Dilip; Pettitt, Bernard M.

2013-12-03T23:59:59.000Z

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.


181

Fast Computation of Solvation Free Energies with Molecular Density Functional Theory: Thermodynamic-Ensemble Partial Molar Volume Corrections  

E-Print Network [OSTI]

Molecular Density Functional Theory (MDFT) offers an efficient implicit- solvent method to estimate molecule solvation free-energies whereas conserving a fully molecular representation of the solvent. Even within a second order ap- proximation for the free-energy functional, the so-called homogeneous reference uid approximation, we show that the hydration free-energies computed for a dataset of 500 organic compounds are of similar quality as those obtained from molecular dynamics free-energy perturbation simulations, with a computer cost reduced by two to three orders of magnitude. This requires to introduce the proper partial volume correction to transform the results from the grand canoni- cal to the isobaric-isotherm ensemble that is pertinent to experiments. We show that this correction can be extended to 3D-RISM calculations, giving a sound theoretical justifcation to empirical partial molar volume corrections that have been proposed recently.

Volodymyr P. Sergiievskyi; Guillaume Jeanmairet; Maximilien Levesque; Daniel Borgis

2014-06-11T23:59:59.000Z

182

Ultrafast Optics and Optical Fiber Communications Laboratory http://purcell.ecn.purdue.edu/~fsoptics/  

E-Print Network [OSTI]

Ultrafast Optics and Optical Fiber Communications Laboratory http, A. M. Weiner Purdue University C. Lin Avanex Corporation Conference on Lasers and Electro Optics;Ultrafast Optics and Optical Fiber Communications Laboratory http://purcell.ecn.purdue.edu/~fsoptics/ 2

Purdue University

183

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

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

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...

184

Ultrafast imaging of complex systems in 3-D at near atomic resolution...  

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

on ultrafast timescales using extremely intense X-ray free-electron laser (XFEL) pulses. One important step toward ultrafast imaging of samples with a single X-ray shot is...

185

Ultrafast optical pulse manipulation in three dimensional-resolved microscope imaging and microfabrication  

E-Print Network [OSTI]

The availability of lasers with femtosecond, ultrafast light pulses provides new opportunities and challenges in instrument design. This thesis addresses three aspects of utilizing ultrafast light pulses in two-photon ...

Kim, Daekeun, Ph. D. Massachusetts Institute of Technology

2009-01-01T23:59:59.000Z

186

Plasmonic Near-Electric Field Enhancement Effects in Ultrafast Photoelectron Emission: Correlated Spatial and Laser Polarization  

E-Print Network [OSTI]

ABSTRACT: Electron emission from single, supported Ag nanocubes excited with ultrafast laser pulses ( = 800 irradiated with ultrafast laser pulses at a photon energy (Eph) below the material work functionPlasmonic Near-Electric Field Enhancement Effects in Ultrafast Photoelectron Emission: Correlated

Mohseni, Hooman

187

ULTRAFAST OPTICS AND OPTICAL FIBER COMMUNICATIONS LABORATORYLEOS 2003 Multiple Output Channel  

E-Print Network [OSTI]

DSTAWG DST Pulse Shaper Fiber ports Imaging optics U.S. Quarter #12;ULTRAFAST OPTICS AND OPTICAL FIBER;ULTRAFAST OPTICS AND OPTICAL FIBER COMMUNICATIONS LABORATORYLEOS 2003 One Guide ­ One Pulse Pulses slab Loss-engineering to control relative pulse amplitude. #12;ULTRAFAST OPTICS AND OPTICAL FIBER

Purdue University

188

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

E-Print Network [OSTI]

advantages over single-pulse laser processing of materials and biological tissues. Ultrafast lasers are often material, as is sometimes the case for nanosecond-pulse ablation; further, pulsetrain-bursts of ultrafast of ultrafast laser pulses, at a repetition rate of 1 MHz or greater, is less likely to leave cracks or residual

Marjoribanks, Robin S.

189

Title of dissertation: ULTRAFAST CONTROL OF SPIN AND MOTION IN TRAPPED IONS  

E-Print Network [OSTI]

, I report here on the first experiments using ultrafast laser pulses to control the internalABSTRACT Title of dissertation: ULTRAFAST CONTROL OF SPIN AND MOTION IN TRAPPED IONS Jonathan and external states of a single trapped ion. I begin with experiments in ultrafast spin control, showing how

Monroe, Christopher

190

Proceedings of SPIE, Vol. 5825, 118-138 (2005) Ultrafast coherent spectroscopy of single semiconductor  

E-Print Network [OSTI]

ultrafast optical pulses to probe and control coherent polarizations. In this article, we review our recentProceedings of SPIE, Vol. 5825, 118-138 (2005) Ultrafast coherent spectroscopy of single work on combining ultrafast spectroscopy and near-field microscopy to probe the nonlinear optical

Peinke, Joachim

191

Characterization of a liquid-crystal ultrafast pulse shaper for ultra-broadband applications  

E-Print Network [OSTI]

Characterization of a liquid-crystal ultrafast pulse shaper for ultra-broadband applications pulse shaping Spatial light modulators Ultrafast optics Femtosecond pulses a b s t r a c t By combining in revised form 22 January 2014 Accepted 28 January 2014 Available online 6 February 2014 Keywords: Ultrafast

192

Single pulse ultrafast laser imprinting of axial dot arrays in bulk glasses C. Mauclair,1,  

E-Print Network [OSTI]

Single pulse ultrafast laser imprinting of axial dot arrays in bulk glasses C. Mauclair,1, A sam- ples were irradiated with 160 fs pulses from an 800 nm Ti:Sapphire amplified ultrafast laser.mauclair@univ-st-etienne.fr Compiled December 20, 2010 Ultrafast laser processing of bulk transparent materials can significantly gain

Paris-Sud XI, Université de

193

Breathing coherent phonons and caps fragmentation in carbon nanotubes following ultrafast laser pulses  

E-Print Network [OSTI]

driven by ultrafast laser pulses.1­3 The necessary conditions for generating such coherent phonons are i is larger than the duration of currently available ultrafast pulses. ii Measurements4­7 determinedBreathing coherent phonons and caps fragmentation in carbon nanotubes following ultrafast laser

Dumitrica,Traian

194

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 emission from the interaction of an ultrafast ( 29 fs), intense ( 1018 W/cm2 ) laser pulse with underdense of such an ultrafast laser pulse with matter and possible new approaches to MeV electron generation. In this paper we

Umstadter, Donald

195

Parametric cascade downconverter for intense ultrafast mid-infrared generation beyond the ManleyRowe  

E-Print Network [OSTI]

codes: 190.2620, 190.4970, 320.7160, 320.7110. Intense and ultrafast optical pulses (durations typ of optical sources that directly produce ultrafast intense pulses at long wavelengths. One technique that has from in- tense ultrafast pulses in the near infrared 800 nm . Recent results that produce intense

Boyer, Edmond

196

Fourier information optics for the ultrafast time domain Andrew M. Weiner  

E-Print Network [OSTI]

of ultrafast pulses. These examples exploit time­ frequency Fourier techniques to perform matched filtering processing of ultrafast pulsed signals, in close analogy with the spatial Fourier techniques used by LeithFourier information optics for the ultrafast time domain Andrew M. Weiner School of Electrical

Purdue University

197

Advances in Ultrafast Control and Probing of Correlated-Electron Materials  

SciTech Connect (OSTI)

In this paper, we present recent results on ultrafast control and probing of strongly correlated-electron materials. We focus on magnetoresistive manganites, applying excitation and probing wavelengths that cover the mid-IR to the soft X-rays. In analogy with near-equilibrium filling and bandwidth control of phase transitions, our approach uses both visible and mid-IR pulses to stimulate the dynamics by exciting either charges across electronic bandgaps or specific vibrational resonances. X-rays are used to unambiguously measure the microscopic electronic, orbital, and structural dynamics. Our experiments dissect and separate the nonequilibrium physics of these compounds, revealing the complex interplay and evolution of spin, lattice, charge, and orbital degrees of freedoms in the time domain.

Wall, Simon; Rini, Matteo; Dhesi, Sarnjeet S.; Schoenlein, Robert W.; Cavalleri, Andrea

2011-02-01T23:59:59.000Z

198

Ultrafast energy transfer from rigid, branched side-chains into a conjugated, alternating copolymer  

SciTech Connect (OSTI)

We present the synthesis and characterization of a benzodithiophene/thiophene alternating copolymer decorated with rigid, singly branched pendant side chains. We characterize exciton migration and recombination dynamics in these molecules in tetrahydrofuran solution, using a combination of static and time-resolved spectroscopies. As control experiments, we also measure electronic relaxation dynamics in isolated molecular analogues of both the side chain and polymer moieties. We employ semi-empirical and time-dependent density functional theory calculations to show that photoexcitation of the decorated copolymer using 395 nm laser pulses results in excited states primarily localized on the pendant side chains. We use ultrafast transient absorption spectroscopy to show that excitations are transferred to the polymer backbone faster than the instrumental response function, ?250 fs.

Griffin, Graham B.; Rolczynski, Brian S.; Linkin, Alexander; McGillicuddy, Ryan D.; Engel, Gregory S., E-mail: gsengel@uchicago.edu [Department of Chemistry, The James Franck Institute, Institute for Biophysical Dynamics, The University of Chicago, Chicago, Illinois 60637 (United States); Lundin, Pamela M. [Department of Chemical Engineering, Stanford University, Stauffer III, 381 North-South Mall, Stanford, California 94305 (United States) [Department of Chemical Engineering, Stanford University, Stauffer III, 381 North-South Mall, Stanford, California 94305 (United States); A. R. Smith Department of Chemistry, Appalachian State University, 417 CAP Building, 525 Rivers Street, Boone, North Carolina 28608 (United States); Bao, Zhenan [Department of Chemical Engineering, Stanford University, Stauffer III, 381 North-South Mall, Stanford, California 94305 (United States)] [Department of Chemical Engineering, Stanford University, Stauffer III, 381 North-South Mall, Stanford, California 94305 (United States)

2014-01-21T23:59:59.000Z

199

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

SciTech Connect (OSTI)

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

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

2013-08-28T23:59:59.000Z

200

Are mixed explicit/implicit solvation models reliable for studying phosphate hydrolysis? A comparative study of continuum, explicit and mixed solvation models.  

E-Print Network [OSTI]

can be written as: pol ? G solv = ? G cav + ? E QM ( Q g ? Qtermed the solvation entropy, -T?S solv ), and the solutenitro pK a ?E gas ?E pol ??G solv -T?S conf ZPE ?G calc ?G

Kamerlin, Shina C. L.

2009-01-01T23:59:59.000Z

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

The Dynamics, Structure, and Conformational Free Energy of Proline-Containing Antifreeze Glycoprotein  

E-Print Network [OSTI]

The Dynamics, Structure, and Conformational Free Energy of Proline-Containing Antifreeze dynamics simulations augmented with free energy calculations using a continuum solvation model. Starting from 10 different NMR structures, 20 ns of dynamics of AFGP were explored. The dynamics show that AFGP

Nguyen, Dat H.

202

CITIUS: An infrared-extreme ultraviolet light source for fundamental and applied ultrafast science  

SciTech Connect (OSTI)

We present the main features of CITIUS, a new light source for ultrafast science, generating tunable, intense, femtosecond pulses in the spectral range from infrared to extreme ultraviolet (XUV). The XUV pulses (about 10{sup 5}-10{sup 8} photons/pulse in the range 14-80 eV) are produced by laser-induced high-order harmonic generation in gas. This radiation is monochromatized by a time-preserving monochromator, also allowing one to work with high-resolution bandwidth selection. The tunable IR-UV pulses (10{sup 12}-10{sup 15} photons/pulse in the range 0.4-5.6 eV) are generated by an optical parametric amplifier, which is driven by a fraction of the same laser pulse that generates high order harmonics. The IR-UV and XUV pulses follow different optical paths and are eventually recombined on the sample for pump-probe experiments. We also present the results of two pump-probe experiments: with the first one, we fully characterized the temporal duration of harmonic pulses in the time-preserving configuration; with the second one, we demonstrated the possibility of using CITIUS for selective investigation of the ultra-fast dynamics of different elements in a magnetic compound.

Grazioli, C.; Gauthier, D.; Ivanov, R.; De Ninno, G. [Laboratory of Quantum Optics, University of Nova Gorica, Nova Gorica (Slovenia) [Laboratory of Quantum Optics, University of Nova Gorica, Nova Gorica (Slovenia); Elettra Sincrotrone Trieste, Trieste (Italy)] [Italy; Callegari, C.; Spezzani, C. [Elettra Sincrotrone Trieste, Trieste (Italy)] [Elettra Sincrotrone Trieste, Trieste (Italy); Ciavardini, A. [Sapienza University, Rome (Italy)] [Sapienza University, Rome (Italy); Coreno, M. [Elettra Sincrotrone Trieste, Trieste (Italy) [Elettra Sincrotrone Trieste, Trieste (Italy); Institute of Inorganic Methodologies and Plasmas (CNR-IMIP), Montelibretti, Roma (Italy); Frassetto, F.; Miotti, P.; Poletto, L. [Institute of Photonics and Nanotechnologies (CNR-IFN), Padova (Italy)] [Institute of Photonics and Nanotechnologies (CNR-IFN), Padova (Italy); Golob, D. [Kontrolni Sistemi d.o.o., Sežana (Slovenia)] [Kontrolni Sistemi d.o.o., Sežana (Slovenia); Kivimäki, A. [Institute of Materials Manufacturing (CNR-IOM), TASC Laboratory, Trieste (Italy)] [Institute of Materials Manufacturing (CNR-IOM), TASC Laboratory, Trieste (Italy); Mahieu, B. [Elettra Sincrotrone Trieste, Trieste (Italy) [Elettra Sincrotrone Trieste, Trieste (Italy); Service des Photons Atomes et Molécules, Commissariat à l'Energie Atomique, Centre d'Etudes de Saclay, Bâtiment 522, 91191 Gif-sur-Yvette (France); Bu?ar, B.; Merhar, M. [Laboratory of Mechanical Processing Technologies, University of Ljubljana, Ljubljana (Slovenia)] [Laboratory of Mechanical Processing Technologies, University of Ljubljana, Ljubljana (Slovenia); Polo, E. [Institute of Organic Synthesis and Photoreactivity (CNR-ISOF), Ferrara (Italy)] [Institute of Organic Synthesis and Photoreactivity (CNR-ISOF), Ferrara (Italy); Ressel, B. [Laboratory of Quantum Optics, University of Nova Gorica, Nova Gorica (Slovenia)] [Laboratory of Quantum Optics, University of Nova Gorica, Nova Gorica (Slovenia)

2014-02-15T23:59:59.000Z

203

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

SciTech Connect (OSTI)

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

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

2014-04-17T23:59:59.000Z

204

Optical Damage Threshold of Silicon for Ultrafast Infrared Pulses  

SciTech Connect (OSTI)

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

205

Ultrafast reduction of the total magnetization in iron  

SciTech Connect (OSTI)

Surprisingly, if a ferromagnet is exposed to an ultrafast laser pulse, its apparent magnetization is reduced within less than a picosecond. Up to now, the total magnetization, i.e., the average spin polarization of the whole valence band, was not detectable on a sub-picosecond time scale. Here, we present experimental data, confirming the ultrafast reduction of the total magnetization. Soft x-ray pulses from the free electron laser in Hamburg (FLASH) extract polarized cascade photoelectrons from an iron layer excited by a femtosecond laser pulse. The spin polarization of the emitted electrons is detected by a Mott spin polarimeter.

Fognini, A., E-mail: afognini@phys.ethz.ch; Michlmayr, T. U.; Salvatella, G.; Vaterlaus, A.; Acremann, Y., E-mail: acremann@solid.phys.ethz.ch [Laboratory for Solid State Physics, Otto-Stern-Weg 1, ETH Zurich, 8093 Zurich (Switzerland); Wetli, C. [Multifunktionale Ferroische Mat., Vladimir-Prelog-Weg 1-5/10, ETH Zurich, 8093 Zurich (Switzerland); Ramsperger, U.; Bähler, T.; Pescia, D. [Laboratory for Solid State Physics, Auguste-Piccard-Hof 1, ETH Zurich, 8093 Zurich (Switzerland); Sorgenfrei, F.; Beye, M.; Eschenlohr, A.; Pontius, N.; Föhlisch, A. [Institut für Methoden und Instrumentierung der Forschung mit Synchrotronstrahlung, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, 12489 Berlin (Germany); Stamm, C. [Institut für Methoden und Instrumentierung der Forschung mit Synchrotronstrahlung, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, 12489 Berlin (Germany); Department of Materials, ETH Zurich, Hönggerbergring 64, 8093 Zurich (Switzerland); Hieke, F.; Dell'Angela, M.; Wurth, W. [Institut für Experimentalphysik and Center for Free-Electron Laser Science, Universität Hamburg, 22607 Hamburg (Germany); Jong, S. de; Dürr, H. A. [SLAC National Accelerator Laboratory, Menlo Park, California 94025 (United States); and others

2014-01-20T23:59:59.000Z

206

Solvation Free Energy of Biomacromolecules: Parameters for a Modified Generalized Born Model Consistent with the AMBER Force Field  

E-Print Network [OSTI]

Solvation Free Energy of Biomacromolecules: Parameters for a Modified Generalized Born Model provides rapid estimates of the electrostatic free energies of solvation for diverse molecules of parameters compatible with the AMBER force field is described. The method is used to estimate free energies

Jayaram, Bhyravabotla

207

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

208

Solvation of molecules in superfluid helium enhances the “interaction induced localization” effect  

SciTech Connect (OSTI)

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

Walewski, ?ukasz, E-mail: Lukasz.Walewski@theochem.rub.de; Forbert, Harald; Marx, Dominik [Lehrstuhl für Theoretische Chemie, Ruhr–Universität Bochum, 44780 Bochum (Germany)] [Lehrstuhl für Theoretische Chemie, Ruhr–Universität Bochum, 44780 Bochum (Germany)

2014-04-14T23:59:59.000Z

209

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

210

Competitive Solvation of (Bis)(trifluoromethanesulfonyl)imide Anion by Acetonitrile and Water  

E-Print Network [OSTI]

Competitive solvation of an ion by two or more solvents is one of the key phenomena determining the identity of our world. Solvation in polar solvents frequently originates from non-additive non-covalent interactions. Pre-parametrized potentials poorly capture these interactions, unless the force field derivation is repeated for every new system. Development cost increases drastically as new chemical species are supplied. This work represents an alternative simulation approach, PM7-MD, by coupling the latest semiempirical parametrization, PM7, with equation-of-motion propagation scheme and temperature coupling. Using a competitive solvation of (bis)(trifluoromethanesulfonyl)imide anion in acetonitrile and water, the work demonstrates efficiency and robustness of PM7-MD.

Chaban, Vitaly

2014-01-01T23:59:59.000Z

211

Ultrafast optical studies of electronic dynamics in semiconductors  

E-Print Network [OSTI]

. Finally, Jacob Khurgin from Johns Hopkins University and Eugene Ya. Sherman from Spain performed theoretical calculations for the current induced second harmonic experiment. I would like to thank all of our collaborators for their excellent work. Finally...

Ruzicka, Brian Andrew

2012-05-31T23:59:59.000Z

212

Ultrafast control of strong-field electron dynamics in solids  

E-Print Network [OSTI]

We review theoretical foundations and some recent progress related to the quest of controlling the motion of charge carriers with intense laser pulses and optical waveforms. The tools and techniques of attosecond science enable detailed investigations of a relatively unexplored regime of nondestructive strong-field effects. Such extremely nonlinear effects may be utilized to steer electron motion with precisely controlled optical fields and switch electric currents at a rate that is far beyond the capabilities of conventional electronics.

Vladislav S. Yakovlev; Stanislav Yu. Kruchinin; Tim Paasch-Colberg; Mark I. Stockman; Ferenc Krausz

2015-02-17T23:59:59.000Z

213

Ultrafast Core-Hole Induced Dynamics in Water  

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

AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr MayAtmosphericNuclear SecurityTensile Strain Switched Ferromagnetism in Layeredof2014 EIA Energy40081AEnergy Storage

214

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

215

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

216

PURDUE UNIVERSITY ULTRAFAST OPTICS & OPTICAL FIBER COMMUNICATIONS LABORATORYA.M. Weiner Andrew M. Weiner, Jason McKinney*, and Shijun Xiao  

E-Print Network [OSTI]

PURDUE UNIVERSITY ULTRAFAST OPTICS & OPTICAL FIBER COMMUNICATIONS LABORATORYA.M. Weiner Andrew M affiliation: Naval Research Labs #12;PURDUE UNIVERSITY ULTRAFAST OPTICS & OPTICAL FIBER COMMUNICATIONS bandwidth #12;PURDUE UNIVERSITY ULTRAFAST OPTICS & OPTICAL FIBER COMMUNICATIONS LABORATORYA.M. Weiner

Purdue University

217

Characterization of iso-CF{sub 2}I{sub 2} in frequency and ultrafast time domains  

SciTech Connect (OSTI)

The photolysis of diiododifluoromethane (CF{sub 2}I{sub 2}) in condensed phases was studied by a combination of matrix isolation and ultrafast time-resolved spectroscopy, in concert with ab initio calculations. Photolysis at wavelengths of 355 or 266 nm of CF{sub 2}I{sub 2}:Ar samples (1:5000) held at {approx}8 K yielded iso-CF{sub 2}I{sub 2} (F{sub 2}C-I-I), a metastable isomer of CF{sub 2}I{sub 2}, characterized here for the first time. The infrared (IR) spectra of this isomer were recorded in matrix experiments, and the derived positions of the C-F stretching modes are in very good agreement with the predictions of high level ab initio calculations, which show that the iso-form is a minimum on the CF{sub 2}I{sub 2} ground state potential energy surface. The formation of this isomer following 350 nm excitation of CF{sub 2}I{sub 2} in room temperature CCl{sub 4} solutions was monitored through its intense C-F stretching mode by means of ultrafast time-resolved IR absorption. Together, matrix isolation and ultrafast IR absorption experiments suggest that the formation of iso-CF{sub 2}I{sub 2} occurs via recombination of CF{sub 2}I radical and I atom. Ultrafast IR experiments detect a delayed rise of iso-CF{sub 2}I-I absorption, placing an upper limit of 400 fs for the C-I bond dissociation and primary geminate recombination processes. The product absorption spectrum recorded 1 ns after 350 nm excitation of CF{sub 2}I{sub 2} in solution is virtually identical to the visible absorption spectrum of iso-CF{sub 2}I{sub 2} trapped in matrix isolation experiments [with subtracted I{sub 2}(X) absorption]. The formation of this isomer in solution at room temperature has direct dynamic implications for the ultrafast production of molecular iodine from electronically excited CF{sub 2}I{sub 2}.

El-Khoury, Patrick Z.; Tarnovsky, Alexander N. [Department of Chemistry and Center for Photochemical Sciences, Bowling Green State University, Bowling Green, Ohio 43403-0001 (United States); George, Lisa; Kalume, Aimable; Reid, Scott A. [Department of Chemistry, Marquette University, Milwaukee, Wisconsin 53201-1881 (United States); Ault, Bruce S. [Department of Chemistry, University of Cincinnati, Cincinnati, Ohio 45221-0172 (United States)

2010-03-28T23:59:59.000Z

218

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

219

Science Challenge Computational modeling of ultrafast digital electronics  

E-Print Network [OSTI]

properties in response to the needs of a particular device or situation. These smart electronics have the potential to lead to entirely new generations of electronic devices--such as military and civilian Science Challenge ­ Computational modeling of ultrafast digital electronics · To understand how

Freericks, Jim

220

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

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

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

222

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. 2 figs.

Smirl, A.; Trebino, R.P.

1999-08-10T23:59:59.000Z

223

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

224

Ultrafast Control of Magnetism in Ferromagnetic Semiconductors via Photoexcited Transient Carriers  

SciTech Connect (OSTI)

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

225

Effect of damping on the laser induced ultrafast switching in rare earth-transition metal alloys  

SciTech Connect (OSTI)

In this paper, we present simulations of thermally induced magnetic switching in ferrimagnetic systems performed with a Landau-Lifshitz-Bloch (LLB) equation for damping constant in a wide range of values. We have systematically studied the GdFeCo ferrimagnet with various concentrations of Gd and compared for some values of parameters the LLB results with atomistic simulations. The agreement is remarkably good, which shows that the dynamics described by the ferrimagnetic LLB is a reasonable approximation of this complex physical phenomenon. As an important element, we show that the LLB is able to also describe the intermediate formation of a ferromagnetic state which seems to be essential to understand laser induced ultrafast switching. The study reveals the fundamental role of damping during the switching process.

Oniciuc, Eugen; Stoleriu, Laurentiu; Cimpoesu, Dorin; Stancu, Alexandru, E-mail: alstancu@uaic.ro [Faculty of Physics and CARPATH Center, “Alexandru Ioan Cuza” University, 700506 Iasi (Romania)

2014-06-02T23:59:59.000Z

226

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

227

Are mixed explicit/implicit solvation models reliable for studying phosphate hydrolysis? A comparative study of continuum, explicit and mixed solvation models.  

SciTech Connect (OSTI)

Phosphate hydrolysis is ubiquitous in biology. However, despite intensive research on this class of reactions, the precise nature of the reaction mechanism remains controversial. In this work, we have examined the hydrolysis of three homologous phosphate diesters. The solvation free energy was simulated by means of either an implicit solvation model (COSMO), hybrid quantum mechanical / molecular mechanical free energy perturbation (QM/MM-FEP) or a mixed solvation model in which N water molecules were explicitly included in the ab initio description of the reacting system (where N=1-3), with the remainder of the solvent being implicitly modelled as a continuum. Here, both COSMO and QM/MM-FEP reproduce Delta Gobs within an error of about 2kcal/mol. However, we demonstrate that in order to obtain any form of reliable results from a mixed model, it is essential to carefully select the explicit water molecules from short QM/MM runs that act as a model for the true infinite system. Additionally, the mixed models tend to be increasingly inaccurate the more explicit water molecules are placed into the system. Thus, our analysis indicates that this approach provides an unreliable way for modelling phosphate hydrolysis in solution.

Kamerlin, Shina C. L.; Haranczyk, Maciej; Warshel, Arieh

2009-05-01T23:59:59.000Z

228

Lithium Phenolates Solvated by Tetrahydrofuran and 1,2-Dimethoxyethane: Structure Determination Using the  

E-Print Network [OSTI]

Lithium Phenolates Solvated by Tetrahydrofuran and 1,2-Dimethoxyethane: Structure Determination: The method of continuous variation in conjunction with 6 Li NMR spectroscopy was used to characterize lithium substrate- and solvent-dependent combinations of lithium phenolate monomers, dimers, trimers, tetramers

Collum, David B.

229

Lithium Diisopropylamide Solvated by Monodentate and Bidentate Ligands: Solution Structures and Ligand Binding  

E-Print Network [OSTI]

Lithium Diisopropylamide Solvated by Monodentate and Bidentate Ligands: Solution Structures, 1997X Abstract: 6Li and 15N NMR spectroscopic studies of lithium diisopropylamide ([6Li]LDA and [6Li,15 are correlated with those obtained previously for lithium hexamethyldisilazide. Introduction Despite

Collum, David B.

230

Heavy water hydration of mannose: the anomeric effect in solvation, laid Nitzan Mayorkas,ab  

E-Print Network [OSTI]

Heavy water hydration of mannose: the anomeric effect in solvation, laid bare Nitzan Mayorkas,3 in a series of `proof of principle' experiments, revealed that these heavy water molecules engage the key, which has the advantage of isotopically isolating the carbohydrate (OH) bands from the water (OD) bands

Davis, Ben G.

231

Studies on free energy calculations. II. A theoretical approach to molecular solvation  

E-Print Network [OSTI]

energies at the particle creation limit. The new theory directly incorporates the weakly attractiveStudies on free energy calculations. II. A theoretical approach to molecular solvation Haluk Resat and Mihaly Mezei Department of Biophysics and Physiology, Mount Sinai School of Medicine, CUNX New York, New

Mezei, Mihaly

232

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

SciTech Connect (OSTI)

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

233

Epsilon-Near-Zero Al-Doped ZnO for Ultrafast Switching at Telecom Wavelengths: Outpacing the Traditional Amplitude-Bandwidth Trade-Off  

E-Print Network [OSTI]

Transparent conducting oxides have recently gained great attention as CMOS-compatible materials for applications in nanophotonics due to their low optical loss, metal-like behavior, versatile/tailorable optical properties, and established fabrication procedures. In particular, aluminum doped zinc oxide (AZO) is very attractive because its dielectric permittivity can be engineered over a broad range in the near infrared and infrared. However, despite all these beneficial features, the slow (> 100 ps) electron-hole recombination time typical of these compounds still represents a fundamental limitation impeding ultrafast optical modulation. Here we report the first epsilon-near-zero AZO thin films which simultaneously exhibit ultra-fast carrier dynamics (excitation and recombination time below 1 ps) and an outstanding reflectance modulation up to 40% for very low pump fluence levels (< 4 mJ/cm2) at the telecom wavelength of 1.3 {\\mu}m. The unique properties of the demonstrated AZO thin films are the result of...

Kinsey, N; Kim, J; Ferrera, M; Shalaev, V M; Boltasseva, A

2015-01-01T23:59:59.000Z

234

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

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

235

Ultrafast formation of the benzoic acid triplet upon ultraviolet photolysis and its sequential photodissociation in solution  

SciTech Connect (OSTI)

Time-resolved infrared (TR-IR) absorption spectroscopy in both the femtosecond and nanosecond time domain has been applied to examine the photolysis of benzoic acid in acetonitrile solution following either 267 nm or 193 nm excitation. By combining the ultrafast and nanosecond TR-IR measurements, both the excited states and the photofragments have been detected and key mechanistic insights were obtained. We show that the solvent interaction modifies the excited state relaxation pathways and thus the population dynamics, leading to different photolysis behavior in solution from that observed in the gas phase. Vibrational energy transfer to solvents dissipates excitation energy efficiently, suppressing the photodissociation and depopulating the excited S{sub 2} or S{sub 3} state molecules to the lowest T{sub 1} state with a rate of {approx}2.5 ps after a delayed onset of {approx}3.7 ps. Photolysis of benzoic acid using 267 nm excitation is dominated by the formation of the T{sub 1} excited state and no photofragments could be detected. The results from TR-IR experiments using higher energy of 193 nm indicate that photodissociation proceeds more rapidly than the vibrational energy transfer to solvents and C-C bond fission becomes the dominant relaxation pathway in these experiments as featured by the prominent observation of the COOH photofragments and negligible yield of the T{sub 1} excited state. The measured ultrafast formation of T{sub 1} excited state supports the existence of the surface intersections of S{sub 2}/S{sub 1}, S{sub 2}/T{sub 2}, and S{sub 1}/T{sub 1}/T{sub 2}, and the large T{sub 1} quantum yield of {approx}0.65 indicates the importance of the excited state depopulation to triplet manifold as the key factor affecting the photophysical and photochemical behavior of the monomeric benzoic acid.

Yang Chunfan; Su Hongmei [Beijing National Laboratory for Molecular Sciences (BNLMS), State Key Laboratory of Molecular Reaction Dynamics, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); Sun Xuezhong; George, Michael W. [School of Chemistry, University of Nottingham, University Park NG7 2RD (United Kingdom)

2012-05-28T23:59:59.000Z

236

Ultrafast time-division demultiplexing of polarization-entangled photons  

E-Print Network [OSTI]

Maximizing the information transmission rate through quantum channels is essential for practical implementation of quantum communication. Time-division multiplexing is an approach for which the ultimate rate requires the ability to manipulate and detect single photons on ultrafast timescales while preserving their quantum correlations. Here we demonstrate the demultiplexing of a train of pulsed single photons using time-to-frequency conversion while preserving their polarization entanglement with a partner photon. Our technique converts a pulse train with 2.69 ps spacing to a frequency comb with 307 GHz spacing which may be resolved using diffraction techniques. Our work enables ultrafast multiplexing of quantum information with commercially available single-photon detectors.

John M. Donohue; Jonathan Lavoie; Kevin J. Resch

2014-10-16T23:59:59.000Z

237

Broadband laser cooling of trapped atoms with ultrafast pulses  

E-Print Network [OSTI]

We demonstrate broadband laser cooling of atomic ions in an rf trap using ultrafast pulses from a modelocked laser. The temperature of a single ion is measured by observing the size of a time-averaged image of the ion in the known harmonic trap potential. While the lowest observed temperature was only about 1 K, this method efficiently cools very hot atoms and can sufficiently localize trapped atoms to produce near diffraction-limited atomic images.

B. B. Blinov; R. N. Kohn Jr.; M. J. Madsen; P. Maunz; D. L. Moehring; C. Monroe

2005-07-07T23:59:59.000Z

238

Ultrafast Time-Resolved Electron Diffraction with Megavolt Electron Beams  

SciTech Connect (OSTI)

An rf photocathode electron gun is used as an electron source for ultrafast time-resolved pump-probe electron diffraction. We observed single-shot diffraction patterns from a 160 nm Al foil using the 5.4 MeV electron beam from the Gun Test Facility at the Stanford Linear Accelerator. Excellent agreement with simulations suggests that single-shot diffraction experiments with a time resolution approaching 100 fs are possible.

Hastings, J.B.; /SLAC; Rudakov, F.M.; /Brown U.; Dowell, D.H.; Schmerge, J.F.; /SLAC; Cardoza, J.D.; /Brown U.; Castro, J.M.; Gierman, S.M.; Loos, H.; /SLAC; Weber, P.M.; /Brown U.

2006-10-24T23:59:59.000Z

239

Femtosecond-scale response of GaAs to ultrafast laser pulses Traian Dumitrica* and Roland E. Allen  

E-Print Network [OSTI]

Femtosecond-scale response of GaAs to ultrafast laser pulses Traian Dumitrica* and Roland E. Allen ordinary heating of the sample by phonon emission, there is convinc- ing evidence that ultrafast pulses of the initial stages of the interaction of a laser pulse with a semiconductor, which show that ultrafast disor

Allen, Roland E.

240

1966 JOURNAL OF LIGHTWAVE TECHNOLOGY, VOL. 15, NO. 10, OCTOBER 1997 Mode Conversion of Ultrafast Pulses by Grating  

E-Print Network [OSTI]

conversion of an ultrafast, ultrawide-bandwidth optical pulse propagating in a layered di- electric waveguide for an ultrafast six-cycle optical pulse over that achieved with standard uniform grating convertors. Index Terms--Dielectric waveguides, FDTD, mode conversion, mode extraction, numerical modeling, ultrafast optical pulses. I

Ziolkowski, Richard W.

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

Optical pumpterahertz probe spectroscopy of dyes in solutions: Probing the dynamics of liquid solvent or solid precipitate?  

E-Print Network [OSTI]

dynamics simulations to investigate ultrafast dynamics following electronic excitation of Coumarin 153 and dynamics, preferably at a molecular level of reso- lution. In particular, solvent relaxation following body of time-resolved spectro- scopic studies, as well as molecular dynamics MD simula- tions have been

KuÂ?el, Petr

242

RADIATION HEAT TRANSFER IN TISSUE WELDING AND SOLDERING WITH ULTRAFAST LASERS  

E-Print Network [OSTI]

RADIATION HEAT TRANSFER IN TISSUE WELDING AND SOLDERING WITH ULTRAFAST LASERS Kyunghan Kim to incorporate transient radiation heat transfer in tissue welding and soldering with use of ultrafast lasers are performed between laser welding and laser soldering. The use of solder is found to substantially enhance

Guo, Zhixiong "James"

243

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

244

Analytic model of electron pulse propagation in ultrafast electron diffraction experiments  

E-Print Network [OSTI]

Analytic model of electron pulse propagation in ultrafast electron diffraction experiments A. M pulses used in ultrafast electron diffraction experiments UED . We assume a Gaussian form to characterize the electron pulse, and derive a system of ordinary differential equations that are solved quickly and easily

Sipe,J. E.

245

Coherent ultrafast pulse synthesis between an optical parametric oscillator and a laser  

E-Print Network [OSTI]

Coherent ultrafast pulse synthesis between an optical parametric oscillator and a laser Jinghua Sun* and Derryck T. Reid Ultrafast Optics Group, School of Engineering and Physical Sciences, Heriot 13, 2009 We have demonstrated coherent pulse synthesis between the carrier-envelope, phase

246

Numerical simulations of self-focusing of ultrafast laser pulses Gadi Fibich*  

E-Print Network [OSTI]

Numerical simulations of self-focusing of ultrafast laser pulses Gadi Fibich* School November 2002; published 7 May 2003 Simulation of nonlinear propagation of intense ultrafast laser pulses, space-time focusing, and self-steepening. Our simulations show that, after the asymmetric temporal pulse

Wang, Xiao-Ping

247

Ultrafast control of donor-bound electron spins with single detuned optical pulses  

E-Print Network [OSTI]

LETTERS Ultrafast control of donor-bound electron spins with single detuned optical pulses KAI on microwave sources--can be attained with broadband optical pulses. One promising ultrafast technique uses single broadband pulses detuned from resonance in a three-level system4 . This technique is robust

Loss, Daniel

248

644 OPTICS LETTERS / Vol. 29, No. 6 / March 15, 2004 General ultrafast pulse measurement using the  

E-Print Network [OSTI]

644 OPTICS LETTERS / Vol. 29, No. 6 / March 15, 2004 General ultrafast pulse measurement using the cross-correlation single-shot sonogram technique Derryck T. Reid and Jesus Garduno-Mejia Ultrafast technique offers exact pulse measurement and real-time pulse monitoring via an intuitive time

249

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: a photocathode, consisting of a 10 nm thin Au film deposited onto a sapphire substrate. Electron pulses

von der Linde, D.

250

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 on ultrafast HET given in Refs. 14­16. In the following we will focus on the case where a tailored laser pulse, Germany Received 31 March 2004; accepted 30 July 2004 Laser pulse control of the photoinduced 90 fs charge

Röder, Beate

251

Ultrafast Third Harmonic Micro-spectroscopy Reveals a Two-Photon Resonance in Human Hemoglobin  

E-Print Network [OSTI]

Ultrafast Third Harmonic Micro-spectroscopy Reveals a Two-Photon Resonance in Human Hemoglobin G Golden, CO 80401 Abstract The recently developed technique of ultrafast third harmonic generation (THG states in physiological solutions of human hemoglobin. Keywords: Third Harmonic Generation, Micro

Kleinfeld, David

252

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.

253

Electron-nuclear correlations for photo-induced dynamics in molecular dimers  

E-Print Network [OSTI]

January 2004; accepted 11 March 2004 Ultrafast photoinduced dynamics of electronic excitation in molecularElectron-nuclear correlations for photo-induced dynamics in molecular dimers Dmitri S. Kilin, Yuri dimers is drastically affected by the dynamic reorganization of inter- and intra- molecular nuclear

254

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.

255

Specific interaction of fluoride ions with aluminum and gallium solvates in an ethylene glycol solutions  

SciTech Connect (OSTI)

The interaction of aluminum chloride and gallium chloride with KF in ethylene glycol solutions with F:M/sup 3 +/ mole ratios approximately equal to 2 includes a step involving the formation of fluorine-containing species, in which the fluoride ions are held in the outer sphere of ethylene glycol solvates of aluminum and gallium. Complexes based on hexacoordinate solvates predominate in the solutions of aluminum, while in the case of gallium, in contrast to aluminum, the coexistence of tetra- and hexacoordinate complexes is characteristic. The configurational equilibrium in the solutions of gallium is one of the causes of the structurization of the solutions, i.e., polymerization due to the formation of H bonds between the fluoride ions and the coordinated ethylene glycol molecules.

Petrosyants, S.P.; Tsabel', E.R.; Buslaev, Yu.A.

1986-01-01T23:59:59.000Z

256

Non-Markovian response of ultrafast coherent electronic ring currents in chiral aromatic molecules in a condensed phase  

SciTech Connect (OSTI)

Results of a theoretical study on non-Markov response for femtosecond laser-driven coherent ring currents in chiral aromatic molecules embedded in a condensed phase are presented. Coherent ring currents are generated by coherent excitation of a pair of quasi-degenerated ?-electronic excited states. The coherent electronic dynamical behaviors are strongly influenced by interactions between the electronic system and phonon bath in a condensed phase. Here, the bath correlation time is not instantaneous but should be taken to be a finite time in ultrashort time-resolved experiments. In such a case, Markov approximation breaks down. A hierarchical master equation approach for an improved semiclassical Drude dissipation model was adopted to examine the non-Markov effects on ultrafast coherent electronic ring currents of (P)-2,2{sup ?}-biphenol in a condensed phase. Time evolution of the coherent ring current derived in the hierarchical master equation approach was calculated and compared with those in the Drude model in the Markov approximation and in the static limit. The results show how non-Markovian behaviors in quantum beat signals of ring currents depend on the Drude bath damping constant. Effects of temperatures on ultrafast coherent electronic ring currents are also clarified.

Mineo, H. [Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 10617, Taiwan (China)] [Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 10617, Taiwan (China); Lin, S. H. [Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 10617, Taiwan (China) [Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 10617, Taiwan (China); Department of Applied Chemistry, Institute of Molecular Science and Center for Interdisciplinary Molecular Science, National Chiao-Tung University, Hsin-Chu 300, Taiwan (China); Fujimura, Y. [Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 10617, Taiwan (China) [Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 10617, Taiwan (China); Department of Chemistry, Graduate School of Science, Tohoku University, Sendai 980-8578 (Japan); Xu, J. [Department of Chemistry, Nankai University, Tianjin 300071 (China) [Department of Chemistry, Nankai University, Tianjin 300071 (China); Department of Chemistry, Hong Kong University of Science and Technology, Kowloon (Hong Kong); Xu, R. X. [Hefei National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei, Anhui 230026 (China)] [Hefei National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei, Anhui 230026 (China); Yan, Y. J. [Department of Chemistry, Hong Kong University of Science and Technology, Kowloon (Hong Kong) [Department of Chemistry, Hong Kong University of Science and Technology, Kowloon (Hong Kong); Hefei National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei, Anhui 230026 (China)

2013-12-07T23:59:59.000Z

257

Time-resolved dynamics in acetonitrile cluster anions CH3CN Ryan M. Young a  

E-Print Network [OSTI]

Time-resolved dynamics in acetonitrile cluster anions ðCH3CN�� n Ryan M. Young a , Graham B December 2009 a b s t r a c t Excited state dynamics of acetonitrile cluster anions, ðCH3CN�� n , were, antiparallel solvent molecules [19,20]. Evidence for two electron solvation motifs in acetonitrile also comes

Neumark, Daniel M.

258

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

SciTech Connect (OSTI)

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

259

Attosecond X-Ray Pulses for Molecular Electronic Dynamics  

E-Print Network [OSTI]

techniques for ultrafast laser pulse characterization. Thethe ultrafast evolution of the driver pulse intensity, weisolated pulse production will enable probing of ultrafast

Abel, Mark Joseph

2010-01-01T23:59:59.000Z

260

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.


261

Optical Damage Threshold of Silicon for Ultrafast Infrared Pulses  

SciTech Connect (OSTI)

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

262

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.

Payne, Stephen A. (Castro Valley, CA); Hayden, Joseph S. (Clarks Summit, PA)

1997-01-01T23:59:59.000Z

263

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

2005-04-05T23:59:59.000Z

264

Photoionisation loading of large Sr+ ion clouds with ultrafast pulses  

E-Print Network [OSTI]

This paper reports on photoionisation loading based on ultrafast pulses of singly-ionised strontium ions in a linear Paul trap. We take advantage of an autoionising resonance of Sr neutral atoms to form Sr+ by two-photon absorption of femtosecond pulses at a wavelength of 431nm. We compare this technique to electron-bombardment ionisation and observe several advantages of photoionisation. It actually allows the loading of a pure Sr+ ion cloud in a low radio-frequency voltage amplitude regime. In these conditions up to 4x10^4 laser-cooled Sr+ ions were trapped.

Sébastien Removille; Romain Dubessy; Quentin Glorieux; Samuel Guibal; Thomas Coudreau; Luca Guidoni; Jean-Pierre Likforman

2008-12-05T23:59:59.000Z

265

Ultrafast laser control of backward superfluorescence towards standoff sensing  

SciTech Connect (OSTI)

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

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

2014-01-13T23:59:59.000Z

266

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

267

Combined Quantum Chemical/Raman Spectroscopic Analyses of Li+ Cation Solvation: Cyclic Carbonate Solvents - Ethylene Carbonate and Propylene Earbonate  

SciTech Connect (OSTI)

Combined computational/Raman spectroscopic analyses of ethylene carbonate (EC) and propylene carbonate (PC) solvation interactions with lithium salts are reported. It is proposed that previously reported Raman analyses of (EC)n-LiX mixtures have utilized faulty assumptions. In the present studies, density functional theory (DFT) calculations have provided corrections in terms of both the scaling factors for the solvent's Raman band intensity variations and information about band overlap. By accounting for these factors, the solvation numbers obtained from two different EC solvent bands are in excellent agreement with one another. The same analysis for PC, however, was found to be quite challenging. Commercially available PC is a racemic mixture of (S)- and (R)-PC isomers. Based upon the quantum chemistry calculations, each of these solvent isomers may exist as multiple conformers due to a low energy barrier for ring inversion, making deconvolution of the Raman bands daunting and inherently prone to significant error. Thus, Raman spectroscopy is able to accurately determine the extent of the EC...Li+ cation solvation interactions using the provided methodology, but a similar analysis of PC...Li+ cation solvation results in a significant underestimation of the actual solvation numbers.

Allen, Joshua L.; Borodin, Oleg; Seo, D. M.; Henderson, Wesley A.

2014-12-01T23:59:59.000Z

268

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

E-Print Network [OSTI]

Accepted Manuscript: ACS Nano, 2014, 8 (5), pp 4836–4847DOI: 10.1021/nn500767b 1 Double Wall Carbon Nanotubes for Wide-Band, Ultrafast Pulse Generation Tawfique Hasan1,*, Zhipei Sun2, PingHeng Tan3, Daniel Popa1, Emmanuel Flahaut4,5, Edmund J. R... , Polymer Composites, Saturable Absorber, Ultrafast Laser. Accepted Manuscript: ACS Nano, 2014, 8 (5), pp 4836–4847DOI: 10.1021/nn500767b 2 ABSTRACT: We demonstrate wideband ultrafast optical pulse generation at 1, 1.5 and 2?m using a single polymer...

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

269

Time Resolved Photoelectron Imaging of Electronic Relaxation Dynamics in Anionic Clusters  

E-Print Network [OSTI]

Solvation in Iodide-Doped Acetonitrile Clusters, Journal ofSolvation in Iodide-doped Acetonitrile Clusters [ReprintedSolvation in Iodide- doped Acetonitrile Clusters", Oli T.

Griffin, Graham Bailey

2009-01-01T23:59:59.000Z

270

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.

271

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

272

UPGRADING METHANE USING ULTRA-FAST THERMAL SWING ADSORPTION  

SciTech Connect (OSTI)

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

273

Calculation of Solvation Free Energies of Charged Solutes Using Mixed Cluster/Continuum Vyacheslav S. Bryantsev, Mamadou S. Diallo,, and William A. Goddard III*,  

E-Print Network [OSTI]

Calculation of Solvation Free Energies of Charged Solutes Using Mixed Cluster/Continuum Models methodologies make systematic errors in the computed free energies because of the incorrect accounting consideration. We analyze two different thermodynamic cycles for calculating the solvation free energies

Goddard III, William A.

274

J. Phys. Chem. 1994, 98, 5113-5111 5773 Free Energy of Solvation, Interaction, and Binding of Arbitrary Charge Distributions Imbedded in  

E-Print Network [OSTI]

J. Phys. Chem. 1994, 98, 5113-5111 5773 Free Energy of Solvation, Interaction, and Binding in a continuum solvent. Background Attempts seeking analytical solutions to the hydration free energies solvation free energies of arbitrary charge distributions with an overall spherical symmetry. This theory

Jayaram, Bhyravabotla

275

Photoinduced Electron Transfer and Solvation in Iodide-doped Acetonitrile Clusters Oli T. Ehrler, Graham B. Griffin, Ryan M. Young, and Daniel M. Neumark*  

E-Print Network [OSTI]

Photoinduced Electron Transfer and Solvation in Iodide-doped Acetonitrile Clusters Oli T. Ehrler acetonitrile clusters I- (CH3CN)n with n ) 5-10. Strong modulations of vertical detachment energies were of the I atom leaving the cavity and rearrangement of the acetonitrile molecules to solvate the electron

Neumark, Daniel M.

276

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

SciTech Connect (OSTI)

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

277

Heteropolymer Sequence Design and Preferential Solvation of Hydrophilic Monomers: One More Application of Random Energy Model  

E-Print Network [OSTI]

In this paper, we study the role of surface of the globule and the role of interactions with the solvent for designed sequence heteropolymers using random energy model (REM). We investigate the ground state energy and surface monomer composition distribution. By comparing the freezing transition in random and designed sequence heteropolymers, we discuss the effects of design. Based on our results, we are able to show under which conditions solvation effect improves the quality of sequence design. Finally, we study sequence space entropy and discuss the number of available sequences as a function of imposed requirements for the design quality.

Longhua Hu; Alexander Y. Grosberg

2007-01-24T23:59:59.000Z

278

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

SciTech Connect (OSTI)

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

279

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.

280

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.

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.


281

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

282

Electromagnetically-driven ultra-fast tool servos for diamond turning  

E-Print Network [OSTI]

This thesis presents the design, implementation, and control of a new class of fast tool servos (FTS). The primary thesis contributions include the design and experimental demonstration of: novel ultra-fast electromagnetic ...

Lu, Xiaodong, Ph. D. Massachusetts Institute of Technology

2005-01-01T23:59:59.000Z

283

Release mechanism of octadecyl rhodamine B chloride from Au nanorods by ultrafast laser pulses  

E-Print Network [OSTI]

We investigated the release of octadecyl rhodamine B chloride (R[subscript 18]) loaded onto cetyltrimethylammonium bromide (CTAB) coated gold nanorods (NR) by pulsed ultrafast laser excitation. R[subscript 18] intercalates ...

Alper, Joshua Daniel

284

Two photon luminescence from quantum dots using broad and narrowband ultrafast laser pulses  

E-Print Network [OSTI]

Nonlinear optical microscopy (NLOM) offers many advantages when imaging intact biological samples. By using ultrafast lasers in the near infrared and two photon excitation (TPE), signal production is limited to the focal volume and provides...

Balasubramanian, Haribhaskar

2009-05-15T23:59:59.000Z

285

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

286

Theory of universal fast orientational dynamics in the isotropic phase of liquid crystals  

E-Print Network [OSTI]

is also capable of examining the short distance scale and short time scale dynamics, and yields universal dynamical behavior in the isotropic phase of liquid crystals on ultrafast time scales and short distance scales. The theoretical development generates a temperature independent power law for the short

Fayer, Michael D.

287

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

288

Two photon luminescence from quantum dots using broad and narrowband ultrafast laser pulses  

E-Print Network [OSTI]

TWO PHOTON LUMINESCENCE FROM QUANTUM DOTS USING BROAD AND NARROWBAND ULTRAFAST LASER PULSES A Thesis by HARIBHASKAR BALASUBRAMANIAN 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 December 2007 Major Subject: Biomedical Engineering TWO PHOTON LUMINESCENCE FROM QUANTUM DOTS USING BROAD AND NARROWBAND ULTRAFAST LASER PULSES A Thesis by HARIBHASKAR...

Balasubramanian, Haribhaskar

2008-10-10T23:59:59.000Z

289

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

SciTech Connect (OSTI)

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

290

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

SciTech Connect (OSTI)

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

291

Solvate Structures and Computational/Spectroscopic Characterization of LiBF4 Electrolytes  

SciTech Connect (OSTI)

Crystal structures have been determined for both LiBF4 and HBF4 solvates?(acetonitrile)2:LiBF4, (ethylene glycol diethyl ether)1:LiBF4, (diethylene glycol diethyl ether)1:LiBF4, (tetrahydrofuran)1:LiBF4, (methyl methoxyacetate)1:LiBF4, (suc-cinonitrile)1:LiBF4, (N,N,N',N",N"-pentamethyldiethylenetriamine)1:HBF4, (N,N,N',N'-tetramethylethylenediamine)3/2:HBF4 and (phenanthroline)2:HBF4. These, as well as other known LiBF4 solvate structures, have been characterized by Raman vibrational spectroscopy to unambiguously assign the anion Raman band positions to specific forms of BF4-...Li+ cation coordination. In addition, complementary DFT calculations of BF4-...Li+ cation complexes have provided additional insight into the challenges associated with accurately interpreting the anion interactions from experimental Raman spectra. This information provides a crucial tool for the characterization of the ionic association interactions within electrolytes.

Seo, D. M.; Boyle, Paul D.; Allen, Joshua L.; Han, Sang D.; Jonsson , Erlendur; Johansson, Patrik; Henderson, Wesley A.

2014-07-21T23:59:59.000Z

292

Ultrafast Extreme Ultraviolet Induced Isomerization of Acetylene Cations  

SciTech Connect (OSTI)

Ultrafast isomerization of acetylene cations ([HC = CH]{sup +}) in the low-lying excited A{sup 2}{Sigma}{sub g}{sup +} state, populated by the absorption of extreme ultraviolet (XUV) photons (38 eV), has been observed at the Free Electron Laser in Hamburg, (FLASH). Recording coincident fragments C{sup +} + CH{sub 2}{sup +} as a function of time between XUV-pump and -probe pulses, generated by a split-mirror device, we find an isomerization time of 52 {+-} 15 fs in a kinetic energy release (KER) window of 5.8 < KER < 8 eV, providing clear evidence for the existence of a fast, nonradiative decay channel.

Jiang, Y.; Rudenko, Artem; Herrwerth, O.; Foucar, L.; Kurka, M.; Kuhnel, K.; Lezius, M.; Kling, Matthias; van Tilborg, Jeroen; Belkacem, Ali; Ueda, K.; Dusterer, S.; Treusch, R.; Schroter, Claus-Dieter; Moshammer, Robbert; Ullrich, Joachim

2011-06-17T23:59:59.000Z

293

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

294

Ultrafast stimulated Raman parallel adiabatic passage by shaped pulses  

E-Print Network [OSTI]

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

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

2009-10-06T23:59:59.000Z

295

Ultrafast electron diffraction with radio-frequency compressed electron pulses  

SciTech Connect (OSTI)

We report on the complete characterization of time resolution in an ultrafast electron diffraction (UED) instrument based on radio-frequency electron pulse compression. The temporal impulse response function of the instrument was determined directly in pump-probe geometry by performing electron-laser pulse cross-correlation measurements using the ponderomotive interaction. With optimal settings, a stable impulse response of 334{+-}10 fs was measured at a bunch charge of 0.1 pC (6.24 Multiplication-Sign 10{sup 5} electrons/pulse); a dramatic improvement compared to performance without pulse compression. Phase stability currently limits the impulse response of the UED diffractometer to the range of 334-500 fs, for bunch charges ranging between 0.1 and 0.6 pC.

Chatelain, Robert P.; Morrison, Vance R.; Godbout, Chris; Siwick, Bradley J. [Departments of Physics and Chemistry, Center for the Physics of Materials, McGill University, Montreal (Canada)

2012-08-20T23:59:59.000Z

296

Ultrafast laser diagnostics to investigate initiation fundamentals in energetic materials.  

SciTech Connect (OSTI)

We present the results of a two year early career LDRD project, which has focused on the development of ultrafast diagnostics to measure temperature, pressure and chemical change during the shock initiation of energetic materials. We compare two single-shot versions of femtosecond rotational CARS to measure nitrogen temperature: chirped-probe-pulse and ps/fs hybrid CARS thermometry. The applicability of measurements to the combustion of energetic materials will be discussed. We have also demonstrated laser shock and particle velocity measurements in thin film explosives using stretched femtosecond laser pulses. We will discuss preliminary results from Al and PETN thin films. Agreement between our results and previous work will be discussed.

Farrow, Darcie; Jilek, Brook Anton; Kohl, Ian Thomas; Kearney, Sean Patrick

2013-08-01T23:59:59.000Z

297

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

298

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.

299

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

300

Dynamics of Solvent Exchange in Organolithium Reagents. Lithium as a Center of Chirality1  

E-Print Network [OSTI]

Dynamics of Solvent Exchange in Organolithium Reagents. Lithium as a Center of Chirality1 Hans J slow enough for direct NMR observation.3,4 However, the detailed nature of interactions with ethers advance was the recent report by Lucht and Collum that individual ether solvates of a lithium amide can

Reich, Hans J.

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

Solvated electron yields in liquid and supercritical ammonia-A statistical mechanical treatment  

SciTech Connect (OSTI)

Earlier the geminate recombination of ions and solvated electrons, produced by ionizing radiation or laser light, was theoretically treated by a model which consisted of a Rydberg atom interacting with the thermodynamic fluctuations of the medium [R. Schiller, J. Chem. Phys. 92, 5527 (1990)]. The theory was applied to liquid-to-supercritical water [R. Schiller and A. Horvath, J. Chem. Phys. 135, 084510 (2011)]. Now it is compared with recent experiments performed on liquid-to-supercritical ammonia [J. Urbanek, A. Dahmen, J. Torres-Alacan, P. Koenigshoven, J. Lindner, and P. Voehringer, J. Phys. Chem. B 116, 2223 (2012)]. The agreement between theory and experiment seems to be reasonable. The treatment is critically assessed.

Schiller, Robert; Horvath, Akos [Centre for Energy Research, P.O.B. 49, Budapest H-1525 (Hungary)

2012-12-07T23:59:59.000Z

302

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

SciTech Connect (OSTI)

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

Nakai, Hiromi, E-mail: nakai@waseda.jp [Department of Chemistry and Biochemistry, School of Advanced Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku, Tokyo 169-8555 (Japan); Research Institute for Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku, Tokyo 169-8555 (Japan); CREST, Japan Science and Technology Agency, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012 (Japan); ESICB, Kyoto University, Kyotodaigaku-Katsura, Kyoto 615-8520 (Japan); Ishikawa, Atsushi [Research Institute for Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku, Tokyo 169-8555 (Japan); ESICB, Kyoto University, Kyotodaigaku-Katsura, Kyoto 615-8520 (Japan)

2014-11-07T23:59:59.000Z

303

Title: Combined passive detection and ultrafast active imaging of cavitation events induced by short pulses of high intensity  

E-Print Network [OSTI]

1 Title: Combined passive detection and ultrafast active imaging of cavitation events induced by short pulses of high intensity ultrasound Authors: Jérôme GATEAU, Jean-François AUBRY, Mathieu PERNOT / INSERM, U979 / Université Denis Diderot, Paris VII Key words: single nucleation events, ultrafast active

Boyer, Edmond

304

Electron-ion relaxation time dependent signal enhancement in ultrafast double-pulse laser-induced breakdown spectroscopy  

E-Print Network [OSTI]

Electron-ion relaxation time dependent signal enhancement in ultrafast double-pulse laser of collinear double-pulse compared to single-pulse ultrafast laser induced breakdown spectroscopy. Our results showed that the significant signal enhancement noticed in the double pulse scheme is strongly correlated

Harilal, S. S.

305

Subnanometer-Scale Measurements of the Interaction of Ultrafast Soft X-Ray Free-Electron-Laser Pulses with Matter  

E-Print Network [OSTI]

lengths greater than 3 A° . This experiment demonstrates that with intense ultrafast pulses, structuralSubnanometer-Scale Measurements of the Interaction of Ultrafast Soft X-Ray Free-Electron-Laser Pulses with Matter Stefan P. Hau-Riege,1,* Henry N. Chapman,1 Jacek Krzywinski,2 Ryszard Sobierajski,2

von der Linde, D.

306

Ultrafast metal-insulator varistors based on tunable Al2O3 tunnel junctions Michael A. Weimer,1,2  

E-Print Network [OSTI]

Ultrafast metal-insulator varistors based on tunable Al2O3 tunnel junctions Michael A. Weimer,1; accepted 4 April 2008; published online 21 April 2008 Ultrafast metal-insulator varistors have been oxide varistors. These characteristics result from the Fowler­Nordheim tunneling of electrons through

George, Steven M.

307

Tuning the magnetization dynamics of nanomagnetic elements through irradiation, composition, and shape  

E-Print Network [OSTI]

set-up utilizes the ultrafast pulses from a Coherent MIRAthe advent of ultrafast lasers, applying optical pulses toof how the laser pulse causes an ultrafast demagnetization

Brandt, Rebekah Katherine

2012-01-01T23:59:59.000Z

308

Upgrading Methane Using Ultra-Fast Thermal Swing Adsorption  

SciTech Connect (OSTI)

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

309

Role of electron-electron interference in ultrafast time-resolved imaging of electronic wavepackets  

SciTech Connect (OSTI)

Ultrafast time-resolved x-ray scattering is an emerging approach to image the dynamical evolution of the electronic charge distribution during complex chemical and biological processes in real-space and real-time. Recently, the differences between semiclassical and quantum-electrodynamical (QED) theory of light-matter interaction for scattering of ultrashort x-ray pulses from the electronic wavepacket were formally demonstrated and visually illustrated by scattering patterns calculated for an electronic wavepacket in atomic hydrogen [G. Dixit, O. Vendrell, and R. Santra, Proc. Natl. Acad. Sci. U.S.A. 109, 11636 (2012)]. In this work, we present a detailed analysis of time-resolved x-ray scattering from a sample containing a mixture of non-stationary and stationary electrons within both the theories. In a many-electron system, the role of scattering interference between a non-stationary and several stationary electrons to the total scattering signal is investigated. In general, QED and semiclassical theory provide different results for the contribution from the scattering interference, which depends on the energy resolution of the detector and the x-ray pulse duration. The present findings are demonstrated by means of a numerical example of x-ray time-resolved imaging for an electronic wavepacket in helium. It is shown that the time-dependent scattering interference vanishes within semiclassical theory and the corresponding patterns are dominated by the scattering contribution from the time-independent interference, whereas the time-dependent scattering interference contribution do not vanish in the QED theory and the patterns are dominated by the scattering contribution from the non-stationary electron scattering.

Dixit, Gopal [Center for Free-Electron Laser Science, DESY, Notkestrasse 85, D-22607 Hamburg (Germany); Santra, Robin [Center for Free-Electron Laser Science, DESY, Notkestrasse 85, D-22607 Hamburg (Germany); Department of Physics, University of Hamburg, D-20355 Hamburg (Germany)

2013-04-07T23:59:59.000Z

310

Ultrafast heterogeneous electron transfer reactions: Comparative theoretical studies on time- and frequency-domain data  

SciTech Connect (OSTI)

Recent theoretical studies on linear absorption spectra of dye-semiconductor systems [perylene attached to nanostructured TiO{sub 2}, L. Wang et al., J. Phys. Chem. B 109, 9589 (2005)] are extended here in different respects. Since the systems show ultrafast photoinduced heterogeneous electron transfer the time-dependent formulation used to compute the absorbance is also applied to calculate the temporal evolution of the sub-100 fs charge injection dynamics after a 10 fs laser-pulse excitation. These studies complement our recent absorption spectra fit for two perylene bridge-anchor group TiO{sub 2} systems. Moreover, the time-dependent formulation of the absorbance is confronted with a frequency-domain description. The latter underlines the central importance of the self-energy caused by the coupling of the dye levels to the semiconductor band continuum. The used model is further applied to study the effect of different parameters such as (1) the dependence on the reorganization energies of the involved intramolecular transitions, (2) the effect of changing the transfer integral which couples the excited dye state with the band continuum, and (3) the effect of the concrete form of the semiconductor band density of states. Emphasis is also put on the case where the charge injection level of the dye is near or somewhat below the band edge. This nicely demonstrates the change from a structureless absorption to a well-resolved vibrational progression including characteristic shifts of the absorption lines which are a direct measure for the dye-semiconductor coupling.

Wang Luxia; Willig, Frank; May, Volkhard [Institut fuer Physik, Humboldt-Universitaet zu Berlin, Newtonstrasse 15, D-12489 Berlin (Germany); Hahn-Meitner-Institut, Abteilung Dynamik von Genzflaechenreaktionen, Glienicker Strasse 100, 14109 Berlin (Germany); Institut fuer Physik, Humboldt-Universitaet zu Berlin, Newtonstrasse 15, D-12489 Berlin (Germany)

2006-01-07T23:59:59.000Z

311

Quantitative comparison of fuel spray images obtained using ultrafast coherent and incoherent double-pulsed illumination  

E-Print Network [OSTI]

We present a quantitative comparison between the high-pressure fuel spray images obtained experimentally using classical imaging with coherent and incoherent ultrafast illuminations recorded using a compatible CMOS camera. The ultrafast, incoherent illumination source was extracted from the supercontinuum generated by tightly focusing the femtosecond laser pulses in water. The average velocity maps computed using time-correlated image-pairs and spray edge complexity computed using the average curvature scale space maps are compared for the spray images obtained with the two illumination techniques and also for the numerically simulated spray using the coupled volume of fluid and level set method for interface tracking (direct numerical simulation or DNS). The spray images obtained with supercontinuum-derived, incoherent, ultrafast illumination are clearer, since the artifacts arising due to laser speckles and multiple diffraction effects are largely reduced and show a better correlation with the DNS results.

Purwar, Harsh; Idlahcen, Saïd; Rozé, Claude; Blaisot, Jean-Bernard; Ménard, Thibault

2015-01-01T23:59:59.000Z

312

Extension - Upgrading Methane Using Ultra-Fast Thermal Swing Adsorption  

SciTech Connect (OSTI)

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

313

ULTRAFAST OUTFLOWS: GALAXY-SCALE ACTIVE GALACTIC NUCLEUS FEEDBACK  

SciTech Connect (OSTI)

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

Wagner, A. Y.; Umemura, M. [Center for Computational Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki, 305-8577 (Japan); Bicknell, G. V., E-mail: ayw@ccs.tsukuba.ac.jp [Research School of Astronomy and Astrophysics, Australian National University, ACT 2611 (Australia)

2013-01-20T23:59:59.000Z

314

An ultrafast phase-change logic device driven by melting processes  

E-Print Network [OSTI]

/device structures are developed with a higher number of resistance levels and resistance-level combinations (11,14). 6 The GST cells have been shown to exhibit ultra-fast Boolean algebraic operations via boosting the energy delivered by electrical-pulse... 1 Title An ultrafast phase-change logic device driven by melting processes Authors D. Loke,1,2,3 J. M. Skelton,1,4 W. J. Wang,5 T. H. Lee,1 R. Zhao,2 T. C. Chong,2,* S. R. Elliott,1,* Affiliations 1Department of Chemistry, University...

Loke, D.; Skelton, J. M.; Wang, W. J.; Lee, T. H.; Zhao, R.; Chong, T. C.; Elliott, S. R.

2014-09-02T23:59:59.000Z

315

Nanoparticle size and morphology control using ultrafast laser induced forward transfer of Ni thin films  

SciTech Connect (OSTI)

We have developed a nanoparticle (NP) printing technique using Ni thin film lift-off from glass substrates after ultrafast irradiation in air. Unique interactions of ultrafast laser pulses with thin films allow for control over NP faceting and size distributions. Control is achieved by changing the laser fluence, film thickness, and film-substrate distance. We demonstrate 20 nm Ni film removal from substrates and rapid NP printing, with size distributions centered at a 6 nm diameter. When the Ni film thickness is lowered to 10 nm, NPs are printed with distributions peaked at a 2 nm diameter.

Murphy, Ryan D. [Applied Physics Program, University of Michigan, Ann Arbor, Michigan 48109 (United States)] [Applied Physics Program, University of Michigan, Ann Arbor, Michigan 48109 (United States); Abere, Michael J.; Schrider, Keegan J.; Yalisove, Steven M. [Department of Materials Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109 (United States)] [Department of Materials Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109 (United States); Torralva, Ben [Department of Atmospheric, Oceanic and Space Sciences, University of Michigan, Ann Arbor, Michigan 48109 (United States)] [Department of Atmospheric, Oceanic and Space Sciences, University of Michigan, Ann Arbor, Michigan 48109 (United States)

2013-08-26T23:59:59.000Z

316

InVited Feature Article Water Dynamics and Proton Transfer in Nafion Fuel Cell Membranes  

E-Print Network [OSTI]

InVited Feature Article Water Dynamics and Proton Transfer in Nafion Fuel Cell Membranes David E is the most widely used polyelectrolyte membrane in fuel cells. Ultrafast infrared spectroscopy of the O but has since become the most commonly used membrane separator in polymer electrolyte membrane fuel cells

Fayer, Michael D.

317

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

318

Generation of sub-30-fs microjoule mid-infrared pulses for ultrafast vibrational  

E-Print Network [OSTI]

compression. http://dx.doi.org/10.1364/OL.38.005008 Understanding ultrafast interactions in solids and con]. The dispersion properties of certain nonlinear optical materials, such as potassium titanyl phosphate (KTP), lithium niobate (LNB), potassium niobate (KNB), and periodically poled stoichiometric lithium tantalate

Borguet, Eric

319

Ultrafast intermolecular energy transfer in heavy water L. Piatkowski,*a  

E-Print Network [OSTI]

Ultrafast intermolecular energy transfer in heavy water L. Piatkowski,*a K. B. Eisenthalb and H. J of the excitation of the OH vibration for different isotopic mixtures of water and heavy water.6 At a low concentration of water in heavy water (o1%) the OH groups are too far apart to show energy transfer within

Eisenthal, Kenneth B.

320

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.

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

Atomic-Scale Perspective of Ultrafast Charge Transfer at a Dye-Semiconductor Interface  

E-Print Network [OSTI]

Atomic-Scale Perspective of Ultrafast Charge Transfer at a Dye-Semiconductor Interface Katrin R3 dye molecules and ZnO nanocrystals within the first picosecond after photoexcitation and from the unique perspective of the Ru reporter atom at the center of the dye. A transient chemical shift of the Ru

Neumark, Daniel M.

322

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

323

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.

324

Coherent matter waves for ultrafast laser pulse characterization M. Winter, M. Wollenhaupt, T. Baumert *  

E-Print Network [OSTI]

Coherent matter waves for ultrafast laser pulse characterization M. Winter, M. Wollenhaupt, T for the characterization of ultrashort laser pulses using coherent matter waves is demonstrated. We emphasize the anal- ogy theoretically and experimentally and is the basis for our laser pulse character- ization technique. We use

Peinke, Joachim

325

Three envelope approach for ultrafast pulse characterization in a pump-probe experiment  

E-Print Network [OSTI]

Three envelope approach for ultrafast pulse characterization in a pump-probe experiment Balakishore of temporally identical ultrashort pulses at the focal point in a pump-probe experiment for potential use, fundamental, and second harmonic spectra, combined with an error minimization pulse retrieval scheme

326

Broadband conversion in an Yb:KYW-pumped ultrafast optical parametric oscillator with a long  

E-Print Network [OSTI]

Broadband conversion in an Yb:KYW-pumped ultrafast optical parametric oscillator with a long-infrared pulses at 3.5-µm from an optical parametric oscillator incorporating a 25- mm MgO:PPLN crystal and synchronously-pumped by chirped pulses from a fiber-amplified Yb:KYW laser. A long nonlinear crystal permits

327

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

SciTech Connect (OSTI)

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

Sterling Backus

2012-05-14T23:59:59.000Z

328

Investigations of ultrafast nuclear response induced by resonant and nonresonant laser pulses  

E-Print Network [OSTI]

Investigations of ultrafast nuclear response induced by resonant and nonresonant laser pulses Anand by ultrashort laser pulses interacting with a two electronic level molecular system. Fully quantum mechanical to implement. The behavior of the first two moments with respect to various parameters such as the pulse

Kumar, Anand T.N.

329

OPTI-583: Computational Optics I: Ultrafast pulses and strong-field light-matter interactions.  

E-Print Network [OSTI]

OPTI-583: Computational Optics I: Ultrafast pulses and strong-field light-matter interactions. Time-power femtosecond pulses. Prerequisites: Knowledge of basic electromagnetic theory (e.g. Phys-241). While previous that govern the interaction of ultrashort pulses with var- ious media, and the Numerical methods track

Arizona, University of

330

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

331

Time-resolved Studies of Phase Transition Dynamics in Strongly Correlated Manganites  

E-Print Network [OSTI]

mrini@lbl.gov Abstract. Ultrafast light pulses can be usedpulses. The material response is investigated using both ultrafast

Rini, M

2010-01-01T23:59:59.000Z

332

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

333

Structural and Magnetic Properties of MCl2 (M = Fe, Mn, Co): Acetonitrile Solvates  

SciTech Connect (OSTI)

M{sup II}Cl{sub 2} (M = Mn, Fe, Co) as their acetonitrile solvates were isolated, and their structural, spectroscopic, and magnetic properties were studied. MCl{sub 2}(NCMe){sub 2} (M = Fe, Mn) form 1-D chains of octahedral M{sup II} ions with four bridging chlorides and two axial MeCN's. The presence of an axial distortion for MFe causes a significant magnetic anisotropy that increases significantly below 150 K; however, {chi}{sub av} [=({chi}{sub {parallel}} + 2{chi}{sub {perpendicular}})/3] almost coincides with the value obtained on a polycrystalline sample. MnCl{sub 2}(NCMe){sub 2} is a paramagnet with a weak antiferromagnetic coupling. Annealing FeCl{sub 2}(NCMe){sub 2} at 55 {sup o}C forms the monosolvate of FeCl{sub 2}(NCMe) composition in which two chains collapse into a double chain with formation of Fe-Cl bonding such that half of the {mu}-Cl's becomes {mu}{sub 3}-Cl's. This material orders magnetically below {Tc} = 4.3 K. For M = Co, paramagnetic tetrahedral [CoCl{sub 3}(NCMe)]{sup -} anions are isolated.

Pokhodnya,K.; Bonner, M.; DiPasquale, A.; Rheingold, A.; Her, J.; Stephens, P.; Park, J.; Kennon, B.; Arif, A.; Miller, J.

2007-01-01T23:59:59.000Z

334

First-Principles Simulations of Chemical Reactions in an HCl Molecule Embedded inside a C or BN Nanotube Induced by Ultrafast Laser Pulses  

SciTech Connect (OSTI)

We show by first-principles simulations that ultrafast laser pulses induce different chemical reactions in a molecule trapped inside a nanotube. A strong laser pulse polarized perpendicular to the tube axis induces a giant bond stretch of an encapsulated HCl molecule in semiconducting carbon nanotube or in a BN nanotube. Depending on the initial orientation of the HCl molecule, the subsequent laser-induced dynamics is different: either complete disintegration or rebonding of the HCl molecule. Radial motion of the nanotube is always observed and a vacancy appears on the tube wall when the HCl is perpendicular to the tube axis. Those results are important to analyze confined nanochemistry and to manipulate molecules and nanostructures encapsulated in organic and inorganic nanotubes.

Miyamoto, Yoshiyuki [Green Innovation Research Laboratories, NEC Corporation, 34 Miyukigaoka, Tsukuba 305-8501 (Japan); Zhang Hong [School of Physical Science and Technology, Sichuan University, Chengdu 610065 (China); Rubio, Angel [Nano-Bio Spectroscopy group and ETSF Scientific Development Centre, Department Fisica de Materiales, Universidad del Pais Vasco, Avenida de Tolosa 72, E-20018 San Sebastian (Spain)

2010-12-10T23:59:59.000Z

335

11 photofragmentation/recombination dynamics in size-selected Ir(COs), cluster ions: Observation of coherent I-I-vibrational motion  

E-Print Network [OSTI]

represent nuclear coherences taking place on a sin- gle potential energy surface. One possible example environment in which the size of a solvent cage surrounding a chro- mophore can potentially be controlled, allowing one to study the effects of increasing solvation on reaction dynam- ics.`" If charged species

Lineberger, W. Carl

336

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.

337

Long-term stable timing distribution of an ultrafast optical pulse train over multiple fiber links with polarization maintaining output  

E-Print Network [OSTI]

The distribution of an ultrafast optical pulse train over multiple fiber links with long-term stable timing precision within 2 femtoseconds rms is accomplished by integrating a polarization maintaining output with 300 meter ...

Cox, Jonathan A.

338

Upgrading Methane Using Ultra-Fast Thermal Swing Adsorption  

SciTech Connect (OSTI)

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. The project is on schedule and on budget. 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. The system has 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 will be initiated in the next fiscal year. 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.

Anna Lee Tonkovich

2004-07-01T23:59:59.000Z

339

Hot-electron-driven charge transfer processes on O2 Pt,,111... surface probed by ultrafast extreme-ultraviolet pulses  

E-Print Network [OSTI]

it with an ultrafast laser pulse, charge transfer induced changes in the platinum-oxygen bond were observedHot-electron-driven charge transfer processes on O2 Ã?Pt,,111... surface probed by ultrafast extreme-ultraviolet pulses C. Lei,1, * M. Bauer,2 K. Read,1 R. Tobey,1 Y. Liu,3 T. Popmintchev,1 M. M. Murnane,1 and H. C

Bauer, Michael

340

Ultra-fast underwater suction traps Olivier Vincenta  

E-Print Network [OSTI]

curvature inversion. This process, that we predict using dynamical simulations and simple theoretical models plants, suction mechanism, functional morphology, fluid dynamics hal-00567016,version1-17Feb2011 Author Martin d'Hères Cedex 02, France b Plant Biomechanics Group Freiburg, Botanic Garden, Faculty of Biology

Boyer, Edmond

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

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

SciTech Connect (OSTI)

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

342

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

343

Dynamic optical properties in graphene: Length versus velocity gauge  

SciTech Connect (OSTI)

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

344

Ultrafast Power Processor for Smart Grid Power Module Development  

SciTech Connect (OSTI)

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

MAITRA, ARINDAM [EPRI] [EPRI; LITWIN, RAY [EPRI] [EPRI; lai, Jason [Enertronics] [Enertronics; Syracuse, David [Silicon Power] [Silicon Power

2012-12-30T23:59:59.000Z

345

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

SciTech Connect (OSTI)

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

Gaal, P.; Shayduk, R. [Helmholtz-Zentrum Berlin fuer Materialien und Energie GmbH, Wilhelm-Conrad-Roentgen Campus, BESSY II, Albert-Einstein-Str. 15, 12489 Berlin (Germany); Schick, D.; Herzog, M.; Bojahr, A.; Goldshteyn, J.; Navirian, H. A.; Leitenberger, W. [Institut fuer Physik und Astronomie, Universitaet Potsdam, Karl-Liebknecht-Str. 24-25, 14476 Potsdam (Germany); Vrejoiu, I. [Max-Planck-Institut fuer Mikrostrukturphysik, Weinberg 2, 06120 Halle (Germany); Khakhulin, D.; Wulff, M. [European Synchrotron Radiation Facility (ESRF), 6 rue Jules Horowitz, 38000 Grenoble (France); Bargheer, M. [Helmholtz-Zentrum Berlin fuer Materialien und Energie GmbH, Wilhelm-Conrad-Roentgen Campus, BESSY II, Albert-Einstein-Str. 15, 12489 Berlin (Germany); Institut fuer Physik und Astronomie, Universitaet Potsdam, Karl-Liebknecht-Str. 24-25, 14476 Potsdam (Germany)

2012-12-10T23:59:59.000Z

346

Ultrafast Charge Separation and Nongeminate Electron-Hole Recombination in Organic Photovoltaics  

E-Print Network [OSTI]

The mechanism of electron-hole separation in organic solar cells is currently hotly debated. Recent experimental work suggests that these charges can separate on extremely short timescales (<100 fs). This can be understood in terms of delocalised transport within fullerene aggregates, which is thought to emerge on short timescales before vibronic relaxation induces polaron formation. However, in the optimal heterojunction morphology, electrons and holes will often re-encounter each other before reaching the electrodes. If such charges trap and cannot separate, then device efficiency will suffer. Here we extend the theory of ultrafast charge separation to incorporate polaron formation, and find that the same delocalised transport used to explain ultrafast charge separation can account for the suppression of nongeminate recombination in the best devices.

Samuel L Smith; Alex W Chin

2014-06-04T23:59:59.000Z

347

Time of flight emission spectroscopy of laser produced nickel plasma: Short-pulse and ultrafast excitations  

SciTech Connect (OSTI)

We report the experimental investigation and comparison of the temporal features of short-pulse (7?ns) and ultrafast (100 fs) laser produced plasmas generated from a solid nickel target, expanding into a nitrogen background. When the ambient pressure is varied in a large range of 10{sup ?6?}Torr to 10{sup 2?}Torr, the plume intensity is found to increase rapidly as the pressure crosses 1?Torr. Time of flight (TOF) spectroscopy of emission from neutral nickel (Ni I) at 361.9?nm (3d{sup 9}({sup 2}D) 4p ? 3d{sup 9}({sup 2}D) 4s transition) reveals two peaks (fast and slow species) in short-pulse excitation and a single peak in ultrafast excitation. The fast and slow peaks represent recombined neutrals and un-ionized neutrals, respectively. TOF emission from singly ionized nickel (Ni II) studied using the 428.5?nm (3p{sup 6}3d{sup 8}({sup 3}P) 4s? 3p{sup 6}3d{sup 9} 4s) transition shows only a single peak for either excitation. Velocities of the neutral and ionic species are determined from TOF measurements carried out at different positions (i.e., at distances of 2?mm and 4?mm, respectively, from the target surface) on the plume axis. Measured velocities indicate acceleration of neutrals and ions, which is caused by the Coulomb pull of the electrons enveloping the plume front in the case of ultrafast excitation. Both Coulomb pull and laser-plasma interaction contribute to the acceleration in the case of short-pulse excitation. These investigations provide new information on the pressure dependent temporal behavior of nickel plasmas produced by short-pulse and ultrafast laser pulses, which have potential uses in applications such as pulsed laser deposition and laser-induced nanoparticle generation.

Smijesh, N.; Chandrasekharan, K. [Laser and Nonlinear Optics Laboratory, Department of Physics, National Institute of Technology Calicut, Calicut 673601 (India); Joshi, Jagdish C.; Philip, Reji, E-mail: reji@rri.res.in [Ultrafast and Nonlinear Optics Lab, Light and Matter Physics Group, Raman Research Institute, Bangalore 560080 (India)

2014-07-07T23:59:59.000Z

348

Measuring molecular electric dipoles using trapped atomic ions and ultrafast laser pulses  

E-Print Network [OSTI]

We study a hybrid quantum system composed of an ion and an electric dipole. We show how a trapped ion can be used to measure the small electric field generated by a classical dipole. We discuss the application of this scheme to measure the electric dipole moment of cold polar molecules, whose internal state can be controlled with ultrafast laser pulses, by trapping them in the vicinity of a trapped ion.

Jordi Mur-Petit; Juan José García-Ripoll

2015-01-12T23:59:59.000Z

349

DeepNet: An Ultrafast Neural Learning Code for Seismic Imaging  

SciTech Connect (OSTI)

A feed-forward multilayer neural net is trained to learn the correspondence between seismic data and well logs. The introduction of a virtual input layer, connected to the nominal input layer through a special nonlinear transfer function, enables ultrafast (single iteration), near-optimal training of the net using numerical algebraic techniques. A unique computer code, named DeepNet, has been developed, that has achieved, in actual field demonstrations, results unattainable to date with industry standard tools.

Barhen, J.; Protopopescu, V.; Reister, D.

1999-07-10T23:59:59.000Z

350

Excited States and Luminescent Properties of UO2F2 and Its Solvated Complexes in Aqueous Solution  

SciTech Connect (OSTI)

The electronic absorption and emission spectra of free UO2F2 and its water solvated complexes below 32,000 cm?1 are investigated at the levels of ab initio CASPT2 and CCSD(T) with inclusion of scalar relativistic and spin-orbit coupling effects. The influence of the water coordination on the electronic spectra of UO2F2 is explored by investigating the excited states of solvated complexes (H2O)nUO2F2 (n = 1?3). In these uranyl-complexes, water coordination is found to have appreciable influence on the 3? (? = 1g) character of the luminescent state and on the electronic spectral shape. The simulated luminescence spectral curves based on the calculated spectral parameters of (H2O)nUO2F2 from CCSD(T) approach agree well with experimental spectra in aqueous solution at both near liquid helium temperature and room temperature. The possible luminescence spectra of free UO2F2 in gas phase are predicted based on CASPT2 and CCSD(T) results, respectively, by considering three symmetric vibration modes. The effect of competition between spin-orbital coupling and ligand field repulsion on the luminescent state properties is discussed.

Su, Jing; Wang, Zheming; Pan, Duoqiang; Li, Jun

2014-08-20T23:59:59.000Z

351

Precision lifetime measurements of a single trapped ion with ultrafast laser pulses D. L. Moehring,* B. B. Blinov, D. W. Gidley, R. N. Kohn, Jr., M. J. Madsen, T. D. Sanderson, R. S. Vallery, and C. Monroe  

E-Print Network [OSTI]

Precision lifetime measurements of a single trapped ion with ultrafast laser pulses D. L. Moehring and ultrafast laser technologies, the ion is excited with picosecond laser pulses from a mode-locked laser excited state lifetime of order nanoseconds by an ultrafast laser pulse duration of order picoseconds

Blinov, Boris

352

Multidiagnostic analysis of ultrafast laser ablation of metals with pulse pair irradiation  

SciTech Connect (OSTI)

Copper targets are irradiated in the ablation regime by pairs of equal, time-delayed collinear laser pulses separated on a timescale going from {approx_equal}2 ps to {approx_equal}2 ns. The ablation plume is characterized by ion probe diagnostic, fast imaging, and temporally and spatially resolved optical emission spectroscopy. The variation in the ablation efficiency with the delay between the pulses is analyzed by measuring the ablation crater profile with a contact profilometer. The second laser pulse modifies the characteristics of the plasma plume produced by the first pulse and the ablation efficiency. The different mechanisms involved in double pulse ultrafast laser ablation are identified and discussed. The experimental findings are interpreted in the frame of a simple model of the interaction of the second pulse with the nascent ablation plume produced by the first pulse. This model yields consistent and quantitative agreement with the experimental findings predicting the observed experimental trends of the ablation depth reduction and ion yield increase with the delay between the pulses, as well as the characteristic timescale of the observed changes. The possibility of controlling the characteristics of the plumes produced during ultrafast laser ablation via an efficient coupling of the energy of the second pulse to the various ablation components produced by the first pulse is of particular interest in ultrafast pulsed laser deposition and microprobe analyses of materials.

Amoruso, S.; Bruzzese, R. [Dipartimento di Scienze Fisiche, Universita degli Studi di Napoli Federico II, Complesso Universitario di Monte S. Angelo, Via Cintia, I-80126 Napoli (Italy); CNR-SPIN, Complesso Universitario di Monte S. Angelo, Via Cintia, I-80126 Napoli (Italy); Wang, X. [CNR-SPIN, Complesso Universitario di Monte S. Angelo, Via Cintia, I-80126 Napoli (Italy); O'Connell, G.; Lunney, J. G. [School of Physics, Trinity College-Dublin, Dublin 2 (Ireland)

2010-12-01T23:59:59.000Z

353

Dynamics of excess electrons in atomic and molecular clusters  

E-Print Network [OSTI]

2.2 Femtosecond laser system Ultrafast pulses are generatedwith ultrafast lasers is that the laser pulse generationultrafast systems, everything which must sync to a laser pulse

Young, Ryan Michael

2011-01-01T23:59:59.000Z

354

Ultrafast thermally induced magnetic switching in synthetic ferrimagnets  

SciTech Connect (OSTI)

Synthetic ferrimagnets are composite magnetic structures formed from two or more anti-ferromagnetically coupled magnetic sublattices with different magnetic moments. Here, we report on atomistic spin simulations of the laser-induced magnetization dynamics on such synthetic ferrimagnets and demonstrate that the application of ultrashort laser pulses leads to sub-picosecond magnetization dynamics and all-optical switching in a similar manner as in ferrimagnetic alloys. Moreover, we present the essential material properties for successful laser-induced switching, demonstrating the feasibility of using a synthetic ferrimagnet as a high density magnetic storage element without the need of a write field.

Evans, Richard F. L., E-mail: richard.evans@york.ac.uk; Ostler, Thomas A.; Chantrell, Roy W. [Department of Physics, University of York, Heslington, York YO10 5DD (United Kingdom); Radu, Ilie [Institut für Methoden und Instrumentierung der Forschung mit Synchrotronstrahlung, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Albert-Einstein-Straße 15, 12489 Berlin (Germany); Rasing, Theo [Radboud University, Institute for Molecules and Materials, Heyendaalsewg 135, 6525 AJ Nijmegen (Netherlands)

2014-02-24T23:59:59.000Z

355

Ultrafast electron cascades in semiconductors driven by intense femtosecond terahertz pulses H. Wen,1 M. Wiczer,3 and A. M. Lindenberg1,2  

E-Print Network [OSTI]

Ultrafast electron cascades in semiconductors driven by intense femtosecond terahertz pulses H. Wen processing. With wavelengths in the far infrared, near­ half-cycle THz pulses can be thought of as ultrafast,1 M. Wiczer,3 and A. M. Lindenberg1,2 1PULSE Institute, Stanford Linear Accelerator Center, Menlo

356

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

SciTech Connect (OSTI)

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

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

2008-07-07T23:59:59.000Z

357

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

358

Hydration structure of salt solutions from ab initio molecular dynamics  

SciTech Connect (OSTI)

The solvation structures of Na{sup +}, K{sup +}, and Cl{sup -} ions in aqueous solution have been investigated using density functional theory (DFT) based Car-Parrinello (CP) molecular dynamics (MD) simulations. CPMD trajectories were collected for systems containing three NaCl or KCl ion pairs solvated by 122 water molecules using three different but commonly employed density functionals (BLYP, HCTH, and PBE) with electron correlation treated at the level of the generalized gradient approximation (GGA). The effect of including dispersion forces was analyzed through the use of an empirical correction to the DFT-GGA scheme. Special attention was paid to the hydration characteristics, especially the structural properties of the first solvation shell of the ions, which was investigated through ion-water radial distribution functions, coordination numbers, and angular distribution functions. There are significant differences between the present results obtained from CPMD simulations and those provided by classical MD based on either the CHARMM force field or a polarizable model. Overall, the computed structural properties are in fair agreement with the available experimental results. In particular, the observed coordination numbers 5.0-5.5, 6.0-6.4, and 6.0-6.5 for Na{sup +}, K{sup +}, and Cl{sup -}, respectively, are consistent with X-ray and neutron scattering studies but differ somewhat from some of the many other recent computational studies of these important systems. Possible reasons for the differences are discussed.

Bankura, Arindam; Carnevale, Vincenzo; Klein, Michael L. [Institute for Computational Molecular Science and Department of Chemistry, Temple University, Philadelphia, Pennsylvania 19122 (United States)

2013-01-07T23:59:59.000Z

359

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

360

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

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

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

E-Print Network [OSTI]

purity hydrogen gas (Praxair). 5.3.3 Electron Microscopy (purity hydrogen gas (Praxair). 6.3.3 UV-Vis, Electron

Wheeler, Damon Andreas

2013-01-01T23:59:59.000Z

362

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.

363

Ultrafast Magnetization Dynamics of SrRuO3 Thin Films  

SciTech Connect (OSTI)

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

364

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

365

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

366

Ultrafast infrared studies of chemical reaction dynamics in room-temperature liquids  

E-Print Network [OSTI]

for acetonitrile MD simulation ..0VE for the eN stretch of acetonitrile and benzonitrile.shows the results for acetonitrile. The directions of the

Yang, H.

2011-01-01T23:59:59.000Z

367

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

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

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368

Lattice and Carrier Dynamics in Quantum-Confined Materials on Ultrafast  

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

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369

Effect of bound state of water on hydronium ion mobility in hydrated Nafion using molecular dynamics simulations  

SciTech Connect (OSTI)

We have performed a detailed analysis of the structural properties of the sulfonate groups in terms of isolated and overlapped solvation shells in the nanostructure of hydrated Nafion membrane using classical molecular dynamics simulations. Our simulations have demonstrated the correlation between the two different areas in bound water region, i.e., the first solvation shell, and the vehicular transport of hydronium ions at different water contents. We have employed a model of the Nafion membrane using the improved force field, which is newly modified and validated by comparing the density and water diffusivity with those obtained experimentally. The first solvation shells were classified into the two types, the isolated area and the overlapped area. The mean residence times of solvent molecules explicitly showed the different behaviors in each of those areas in terms of the vehicular transport of protons: the diffusivity of classical hydronium ions in the overlapped area dominates their total diffusion at lower water contents while that in the isolated area dominates for their diffusion at higher water contents. The results provided insights into the importance role of those areas in the solvation shells for the diffusivity of vehicular transport of hydronium ions in hydrated Nafion membrane.

Mabuchi, Takuya, E-mail: mabuchi@nanoint.ifs.tohoku.ac.jp [Graduate School of Engineering, Tohoku University, Sendai, Miyagi 980-8577 (Japan); Tokumasu, Takashi [Institute of Fluid Science, Tohoku University, Sendai, Miyagi 980-8577 (Japan)

2014-09-14T23:59:59.000Z

370

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

371

Ultraslow dissociation of the H{sub 2}{sup +} molecular ion via two-color ultrafast laser pulses  

SciTech Connect (OSTI)

We report a mode of dissociative ionization in an intense two-color laser field. When bond softened by the superposition of 800 and 400 nm ultrafast laser pulses in a narrow intensity range, H{sub 2}{sup +} molecular ions experience ultraslow dissociation. This near-zero kinetic-energy release is supported by theoretical simulations and two-color field-dressed adiabatic potential curves. Furthermore, we show that the shift to lower energy of a known bond-softened peak can be explained by the influence of a two-color field-induced potential well. Such ultraslow dissociation can facilitate ultrafast time-resolved spectroscopy of molecules.

Moser, B.; Gibson, G. N. [Department of Physics, University of Connecticut, Storrs, Connecticut 06269 (United States)

2009-10-15T23:59:59.000Z

372

Progresses in Ab Initio QM/MM Free Energy Simulations of Electrostatic Energies in Proteins: Accelerated QM/MM Studies of pKa, Redox Reactions and Solvation Free Energies  

E-Print Network [OSTI]

an acid in a protein and water respectively, ? G solv w and? G solv p represent the difference in solvation energy ofin protein, (that is, ? G solv w ( AH ) ). Subsequently, 1

Kamerlin, Shina C. L.

2009-01-01T23:59:59.000Z

373

Spatio-temporal mapping of ablated species in ultrafast laser-produced graphite plasmas  

SciTech Connect (OSTI)

We studied the spatial and temporal distributions of ionic, neutral, and molecular species generated by femtosecond laser produced plasma under varying ambient nitrogen gas pressures. Plasmas were generated by irradiating planar graphite targets using 40 fs pulses of 800 nm radiation from a Ti:Sapphire laser. The results show that in the presence of an ambient gas, the molecular species spatial extension and lifetime are directly correlated to the evolution of excited ions. The present studies also provide valuable insights into the evolution history of various species and their excitation during ultrafast laser ablation.

Al-Shboul, K. F.; Harilal, S. S.; Hassanein, A. [Center for Materials Under Extreme Environment, School of Nuclear Engineering, Purdue University, West Lafayette, Indiana 47907 (United States)

2012-05-28T23:59:59.000Z

374

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 fs durations limiting the range of phenomena that can be studied with this technique. We review the state of the the art of UED in this respect and propose a practical design for reflectron based pulse compression which utilizes only electro-static optics and has a tunable temporal focal point. Our simulation shows that this scheme is capable of compressing an electron pulse containing 100,000 electrons with 60:1 temporal compression ratio.

Wang, Yihua

2013-01-01T23:59:59.000Z

375

Pump-probe imaging of laser-induced periodic surface structures after ultrafast irradiation of Si  

SciTech Connect (OSTI)

Ultrafast pump-probe microscopy has been used to investigate laser-induced periodic surface structure (LIPSS) formation on polished Si surfaces. A crater forms on the surface after irradiation by a 150 fs laser pulse, and a second, subsequent pulse forms LIPSS within the crater. Sequentially delayed images show that LIPSS with a periodicity slightly less than the fundamental laser wavelength of 780 nm appear on Si surfaces ?50 ps after arrival of the second pump laser pulse, well after the onset of melting. LIPSS are observed on the same timescale as material removal, suggesting that their formation involves material ejection.

Murphy, Ryan D. [Applied Physics Program, University of Michigan, Ann Arbor, Michigan 48109 (United States)] [Applied Physics Program, University of Michigan, Ann Arbor, Michigan 48109 (United States); Torralva, Ben [Department of Atmospheric, Oceanic and Space Sciences, University of Michigan, Ann Arbor, Michigan 48109 (United States)] [Department of Atmospheric, Oceanic and Space Sciences, University of Michigan, Ann Arbor, Michigan 48109 (United States); Adams, David P. [Sandia National Laboratories, Albuquerque, New Mexico 87123 (United States)] [Sandia National Laboratories, Albuquerque, New Mexico 87123 (United States); Yalisove, Steven M. [Department of Materials Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109 (United States)] [Department of Materials Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109 (United States)

2013-09-30T23:59:59.000Z

376

Ultrafast X-ray Spectroscopy of Warm Dense Matter | Stanford Synchrotron  

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

AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr May JunDatastreamsmmcrcalgovInstrumentsrucLasDelivered energy consumption by sectorlong version) The0Radiation Lightsource Ultrafast

377

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

SciTech Connect (OSTI)

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

378

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

SciTech Connect (OSTI)

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

379

Ultrafast laser based coherent control methods for explosives detection  

SciTech Connect (OSTI)

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

380

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

DOE Patents [OSTI]

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

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

2011-03-22T23:59:59.000Z

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

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

382

IEEE Trans Ultrason Ferroelectr Freq Control . Author manuscript Combined passive detection and ultrafast active imaging of cavitation  

E-Print Network [OSTI]

Gateaué ô Abstract The activation of natural gas nuclei to induce larger and ultrafast active imaging over a large volume and with the same multi-element probe. Bubble nucleation ; ultrasonography ; Phantoms, Imaging ; Sheep ; Signal Processing, Computer-Assisted ; Transducers ; Ultrasonography

Paris-Sud XI, Université de

383

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

384

Investigation on properties of ultrafast switching in a bulk gallium arsenide avalanche semiconductor switch  

SciTech Connect (OSTI)

Properties of ultrafast switching in a bulk gallium arsenide (GaAs) avalanche semiconductor switch based on semi-insulating wafer, triggered by an optical pulse, were analyzed using physics-based numerical simulations. It has been demonstrated that when a voltage with amplitude of 5.2?kV is applied, after an exciting optical pulse with energy of 1??J arrival, the structure with thickness of 650??m reaches a high conductivity state within 110 ps. Carriers are created due to photons absorption, and electrons and holes drift to anode and cathode terminals, respectively. Static ionizing domains appear both at anode and cathode terminals, and create impact-generated carriers which contribute to the formation of electron-hole plasma along entire channel. When the electric field in plasma region increases above the critical value (?4?kV/cm) at which the electrons drift velocity peaks, a domain comes into being. An increase in carrier concentration due to avalanche multiplication in the domains reduces the domain width and results in the formation of an additional domain as soon as the field outside the domains increases above ?4?kV/cm. The formation and evolution of multiple powerfully avalanching domains observed in the simulations are the physical reasons of ultrafast switching. The switch exhibits delayed breakdown with the characteristics affected by biased electric field, current density, and optical pulse energy. The dependence of threshold energy of the exciting optical pulse on the biased electric field is discussed.

Hu, Long, E-mail: hulong-1226@126.com [Key Laboratory for Physical Electronics and Devices of the Ministry of Education, Xi'an Jiaotong University, Xi'an 710049 (China); Science and Technology on High Power Microwave Laboratory, Northwest Institute of Nuclear Technology, Xi'an 710024 (China); Su, Jiancang; Ding, Zhenjie; Hao, Qingsong; Yuan, Xuelin [Science and Technology on High Power Microwave Laboratory, Northwest Institute of Nuclear Technology, Xi'an 710024 (China)

2014-03-07T23:59:59.000Z

385

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

ScienceCinema (OSTI)

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

Li, Weizhong [San Diego Supercomputer Center

2013-01-22T23:59:59.000Z

386

Semiclassical analysis of quantum dynamics  

E-Print Network [OSTI]

Simulating the molecular dynamics (MD) using classical or semi-classical trajectories provides important details for the understanding of many chemical reactions, protein folding, drug design, and solvation effects. MD simulations using trajectories have achieved great successes in the computer simulations of various systems, but it is difficult to incorporate quantum effects in a robust way. Therefore, improving quantum wavepacket dynamics and incorporating nonadiabatic transitions and quantum effects into classical and semi-classical molecular dynamics is critical as well as challenging. In this paper, we present a MD scheme in which a new set of equations of motion (EOM) are proposed to effectively propagate nuclear trajectories while conserving quantum mechanical energy which is critical for describing quantum effects like tunneling. The new quantum EOM is tested on a one-state one-dimensional and a two-state two-dimensional model nonadiabatic systems. The global quantum force experienced by each trajectory promotes energy redistribution among the bundle of trajectories, and thus helps the individual trajectory tunnel through the potential barrier higher than the energy of the trajectory itself. Construction of the new quantum force and EOM also provides a better way to treat the issue of back-reaction in mixed quantum-classical (MQC) methods, i.e. self-consistency between quantum degrees of freedom (DOF) and classical DOF.

Siyang Yang

2011-11-15T23:59:59.000Z

387

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

SciTech Connect (OSTI)

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

388

Ultra-fast photoluminescence as a diagnostic for laser damage initiation  

SciTech Connect (OSTI)

Using high-sensitivity confocal time-resolved photoluminescence (CTP) techniques, we report an ultra-fast photoluminescence (40ps-5ns) from impurity-free surface flaws on fused silica, including polished, indented or fractured surfaces of fused silica, and from laser-heated evaporation pits. This fast photoluminescence (PL) is not associated with slower point defect PL in silica which has characteristic decay times longer than 5ns. Fast PL is excited by the single photon absorption of sub-band gap light, and is especially bright in fractures. Regions which exhibit fast PL are strongly absorptive well below the band gap, as evidenced by a propensity to damage with 3.5eV ns-scale laser pulses, making CTP a powerful non-destructive diagnostic for laser damage in silica. The use of CTP to provide insights into the nature of damage precursors and to help develop and evaluate new damage mitigation strategies will be presented.

Laurence, T A; Bude, J D; Shen, N; Miller, P E; Steele, W A; Guss, G; Adams, J J; Wong, L L; Feit, M D; Suratwala, T I

2009-10-30T23:59:59.000Z

389

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

SciTech Connect (OSTI)

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

390

Efficient Photoionization-Loading of Trapped Cadmium Ions with Ultrafast Pulses  

E-Print Network [OSTI]

Atomic cadmium ions are loaded into radiofrequency ion traps by photoionization of atoms in a cadmium vapor with ultrafast laser pulses. The photoionization is driven through an intermediate atomic resonance with a frequency-quadrupled mode-locked Ti:Sapphire laser that produces pulses of either 100 fsec or 1 psec duration at a central wavelength of 229 nm. The large bandwidth of the pulses photoionizes all velocity classes of the Cd vapor, resulting in high loading efficiencies compared to previous ion trap loading techniques. Measured loading rates are compared with a simple theoretical model, and we conclude that this technique can potentially ionize every atom traversing the laser beam within the trapping volume. This may allow the operation of ion traps with lower levels of background pressures and less trap electrode surface contamination. The technique and laser system reported here should be applicable to loading most laser-cooled ion species.

L. Deslauriers; M. Acton; B. B. Blinov; K. -A. Brickman; P. C. Haljan; W. K. Hensinger; D. Hucul; S. Katnik; R. N. Kohn, Jr.; P. J. Lee; M. J. Madsen; P. Maunz; S. Olmschenk; D. L. Moehring; D. Stick; J. Sterk; M. Yeo; K. C. Younge; C. Monroe

2006-08-04T23:59:59.000Z

391

Four-level atomic interferometer driven by shaped ultrafast laser pulses  

SciTech Connect (OSTI)

We analyze the behavior of a four-state, two-path atomic interferometer driven by shaped ultrafast laser pulses. The laser pulses interact with atomic rubidium, exciting the atoms to the 5D state via two intermediate resonances (the 5P{sub 1/2} and 5P{sub 3/2}). The relative phase of the two paths can be modified by applying a varying spectral phase at the wavelength corresponding to one of the resonant transitions for each pathway. We trace out the behavior of the system from the simplest case of weak-field excitation with resonant fields to strong-field excitation with a broadband source. Our measurements and analysis reveal that while interference is observed for all field strengths and spectral widths, the character of the interference changes substantially.

Clow, Stephen; Weinacht, Thomas [Department of Physics, Stony Brook University, Stony Brook, New York 11794 (United States)

2010-08-15T23:59:59.000Z

392

Ultrafast terahertz-induced response of GeSbTe phase-change materials  

SciTech Connect (OSTI)

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

Shu, Michael J. [Department of Applied Physics, Stanford University, Stanford, California 94305 (United States); Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025 (United States); Zalden, Peter [Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025 (United States); PULSE Institute, SLAC National Accelerator Laboratory, Menlo Park, California 94025 (United States); Chen, Frank [Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025 (United States); Department of Electrical Engineering, Stanford University, Stanford, California 94305 (United States); Weems, Ben [Department of Materials Science and Engineering, Stanford University, Stanford, California 94305 (United States); Chatzakis, Ioannis [Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025 (United States); Xiong, Feng; Jeyasingh, Rakesh; Pop, Eric; Philip Wong, H.-S. [Department of Electrical Engineering, Stanford University, Stanford, California 94305 (United States); Hoffmann, Matthias C. [SLAC National Accelerator Laboratory, Menlo Park, California 94025 (United States); Wuttig, Matthias [I. Physikalisches Institut, RWTH Aachen University, 52056 Aachen (Germany); JARA–Fundamentals of Information Technology, RWTH Aachen University, 52056 Aachen (Germany); Lindenberg, Aaron M., E-mail: aaronl@stanford.edu [Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025 (United States); PULSE Institute, SLAC National Accelerator Laboratory, Menlo Park, California 94025 (United States); Department of Materials Science and Engineering, Stanford University, Stanford, California 94305 (United States)

2014-06-23T23:59:59.000Z

393

Collinear, two-color optical Kerr effect shutter for ultrafast time-resolved imaging  

E-Print Network [OSTI]

Imaging with ultrashort exposure times is generally achieved with a crossed-beam geometry. In the usual arrangement, an off-axis gating pulse induces birefringence in a medium exhibiting a strong Kerr response (commonly carbon disulfide) which is followed by a polarizer aligned to fully attenuate the on-axis imaging beam. By properly timing the gate pulse, imaging light experiences a polarization change allowing time-dependent transmission through the polarizer to form an ultrashort image. The crossed-beam system is effective in generating short gate times, however, signal transmission through the system is complicated by the crossing angle of the gate and imaging beams. This work presents a robust ultrafast time-gated imaging scheme based on a combination of type-I frequency doubling and a collinear optical arrangement in carbon disulfide. We discuss spatial effects arising from crossed-beam Kerr gating, and examine the imaging spatial resolution and transmission timing affected by collinear activation of th...

Purwar, Harsh; Rozé, Claude; Sedarsky, David; Blaisot, Jean-Bernard

2015-01-01T23:59:59.000Z

394

An ultrafast angle-resolved photoemission apparatus for measuring complex materials  

SciTech Connect (OSTI)

We present technical specifications for a high resolution time- and angle-resolved photoemission spectroscopy setup based on a hemispherical electron analyzer and cavity-dumped solid state Ti:sapphire laser used to generate pump and probe beams, respectively, at 1.48 and 5.93 eV. The pulse repetition rate can be tuned from 209 Hz to 54.3 MHz. Under typical operating settings the system has an overall energy resolution of 23 meV, an overall momentum resolution of 0.003 A{sup -1}, and an overall time resolution of 310 fs. We illustrate the system capabilities with representative data on the cuprate superconductor Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8+{delta}}. The descriptions and analyses presented here will inform new developments in ultrafast electron spectroscopy.

Smallwood, Christopher L.; Lanzara, Alessandra [Department of Physics, University of California, Berkeley, California 94720 (United States); Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Jozwiak, Christopher [Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Zhang Wentao [Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)

2012-12-15T23:59:59.000Z

395

Study of the subpicosecond rotational molecular dynamics in liquids  

SciTech Connect (OSTI)

The parameters of the femtosecond vibration-rotation molecular dynamics of liquid acetonitrile CH{sub 3}CN, trimethylacetonitrile (CH{sub 3}){sub 3}CCN, propionitrile CH{sub 3}CH{sub 2}CN, fluoroform CHF{sub 3}, and chloroform CHCl{sub 3} are found by analysing the ultrafast optical Kerr effect. The influence of the molecular structure on the features of rotational (diffusion and libration) motions is studied. It is shown that the distribution of libration frequencies is described by the Maxwell distribution. (laser applications and other topics in quantum electronics)

Nikiforov, V G; Lobkov, Vladimir S [E.K.Zavoisky Physical-Technical Institute, Kazan Scientific Center, Russian Academy of Sciences, Kazan (Russian Federation)

2006-10-31T23:59:59.000Z

396

Structure and dynamics of electrical double layers in organic electrolytes  

SciTech Connect (OSTI)

The organic electrolyte of tetraethylammonium tetrafluoroborate (TEABF{sub 4}) in the aprotic solvent of acetonitrile (ACN) is widely used in electrochemical systems such as electrochemical capacitors. In this paper, we examine the solvation of TEA{sup +} and BF{sub 4}{sup -} in ACN, and the structure, capacitance, and dynamics of the electrical double layers (EDLs) in the TEABF{sub 4}-ACN electrolyte using molecular dynamics simulations complemented with quantum density functional theory calculations. The solvation of TEA+ and BF4- ions is found to be much weaker than that of small inorganic ions in aqueous solutions, and the ACN molecules in the solvation shell of both types of ions show only weak packing and orientational ordering. These solvation characteristics are caused by the large size, charge delocalization, and irregular shape (in the case of TEA+ cation) of the ions. Near neutral electrodes, the double-layer structure in the organic electrolyte exhibits a rich organization: the solvent shows strong layering and orientational ordering, ions are significantly contact-adsorbed on the electrode, and alternating layers of cations/anions penetrate ca. 1.1 nm into the bulk electrolyte. The significant contact adsorption of ions and the alternating layering of cation/anion are new features found for EDLs in organic electrolytes. These features essentially originate from the fact that van der Waals interactions between organic ions and the electrode are strong and the partial desolvation of these ions occurs easily, as a result of the large size of the organic ions. Near charged electrodes, distinct counter-ion concentration peaks form, and the ion distribution cannot be described by the Helmholtz model or the Helmholtz + Poisson-Boltzmann model. This is because the number of counter-ions adsorbed on the electrode exceeds the number of electrons on the electrode, and the electrode is over-screened in parts of the EDL. The computed capacitances of the EDLs are in good agreement with that inferred from experimental measurements. Both the rotations (ACN only) and translations of interfacial ACN and ions are found to slow down as the electrode is electrified. We also observe an asymmetrical dependence of these motions on the sign of the electrode charge. The rotation/diffusion of ACN and the diffusion of ions in the region beyond the first ACN or ion layer differ only weakly from those in the bulk

Huang, Jingsong [ORNL; Sumpter, Bobby G [ORNL; Meunier, Vincent [ORNL; Qiao, Rui [ORNL; Feng, Guang [Clemson University

2010-01-01T23:59:59.000Z

397

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

398

650-nJ pulses from a cavity-dumped Yb:fiber-pumped ultrafast optical parametric oscillator  

E-Print Network [OSTI]

650-nJ pulses from a cavity-dumped Yb:fiber- pumped ultrafast optical parametric oscillator Tobias.p.lamour@hw.ac.uk Abstract: Sub-250-fs pulses with energies of up to 650 nJ and peak powers up to 2.07 MW were generated from a cavity-dumped optical parametric oscillator, synchronously-pumped at 15.3 MHz with sub-400-fs pulses from

399

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

SciTech Connect (OSTI)

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

400

Isomorphic classical molecular dynamics model for an excess electronin a supercritical fluid  

SciTech Connect (OSTI)

Ring polymer molecular dynamics (RPMD) is used to directly simulate the dynamics of an excess electron in a supercritical fluid over a broad range of densities. The accuracy of the RPMD model is tested against numerically exact path integral statistics through the use of analytical continuation techniques. At low fluid densities, the RPMD model substantially underestimates the contribution of delocalized states to the dynamics of the excess electron. However, with increasing solvent density, the RPMD model improves, nearly satisfying analytical continuation constraints at densities approaching those of typical liquids. In the high density regime, quantum dispersion substantially decreases the self-diffusion of the solvated electron. In this regime where the dynamics of the electron is strongly coupled to the dynamics of the atoms in the fluid, trajectories that can reveal diffusive motion of the electron are long in comparison to {beta}{h_bar}.

Miller III, Thomas F.

2008-08-04T23:59:59.000Z

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

Combining Dissociative Ionization Pump–Probe Spectroscopy and ab initio Calculations to Interpret Dynamics and Control Through Conical Intersections  

SciTech Connect (OSTI)

Nonadiabatic processes play an important role in molecular dynamics, and understanding these processes better can help interpret and guide control over molecules. We are using high level electronic structure calculations in combination with intense, shaped, ultrafast laser pulses to study excited state dynamics in the nucleic acid bases, cytosine and uracil. These molecules have very short excited state lifetimes as they relax radiationless through conical intersections after absorption of UV radiation. The presence of more than one relaxation pathway provides the possibility to control which pathway can be involved in the dynamics. In our approach the molecules were excited using ultrafast laser pulses in the deep UV and then probed with strong field near infrared pulses which ionize and dissociate the molecules. Key to this approach is the fact that different fragments exhibit different dynamics and we can correlate these fragments, and their associated dynamics, to the various pathways involved in the neutral dynamics. Multiconfigurational electronic structure methods were used to calculate potential energy surfaces of the neutral and ionic states involved in the dynamics. Calculating mechanisms for fragmentation in the ion enables us to relate specific fragments to different neutral pathways, and use them as signatures to follow the dynamics. Possibilities for control are also discussed.

Matsika, Spiridoula; Zhou, Congyi; Kotur, Marija; Weinacht, Thomas C.

2011-06-27T23:59:59.000Z

402

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

403

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

SciTech Connect (OSTI)

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

404

Molecular dynamics of excited state intramolecular proton transfer: 3-hydroxyflavone in solution  

SciTech Connect (OSTI)

The ultrafast enol-keto photoisomerization in the lowest singlet excited state of 3-hydroxyflavone is investigated using classical molecular dynamics in conjunction with empirical valence bond (EVB) potentials for the description of intramolecular interactions, and a molecular mechanics and variable partial charge model, dependent on transferring proton position, for the description of solute-solvent interactions. A parallel multi-level genetic program was used to accurately fit the EVB potential energy surfaces to high level ab initio data. We have studied the excited state intramolecular proton transfer (ESIPT) reaction in three different solvent environments: methylcyclohexane, acetonitrile, and methanol. The effects of the environment on the proton transfer time and the underlying mechanisms responsible for the varied time scales of the ESIPT reaction rates are analyzed. We find that simulations with our EVB potential energy surfaces accurately reproduce experimentally determined reaction rates, fluorescence spectra, and vibrational frequency spectra in all three solvents. Furthermore, we find that the ultrafast ESIPT process results from a combination of ballistic transfer, and intramolecular vibrational redistribution, which leads to the excitation of a set of low frequency promoting vibrational modes. From this set of promoting modes, we find that an O-O in plane bend and a C-H out of plane bend are present in all three solvents, indicating that they are fundamental to the ultrafast proton transfer. Analysis of the slow proton transfer trajectories reveals a solvent mediated proton transfer mechanism, which is diffusion limited.

Bellucci, Michael A.; Coker, David F. [Department of Chemistry, Boston University, 590 Commonwealth Avenue, Boston, Massachusetts 02215 (United States)

2012-05-21T23:59:59.000Z

405

Can Natural Sunlight Induce Coherent Exciton Dynamics?  

E-Print Network [OSTI]

Excitation of a model photosynthetic molecular aggregate by incoherent sunlight is systematically examined. For a closed system, the excited state coherence induced by the sunlight oscillates with an average amplitude that is inversely proportional to the excitonic gap, and reaches a stationary amplitude that depends on the temperature and coherence time of the radiation field. For an open system, the light-induced dynamical coherence relaxes to a static coherence determined by the non-canonical thermal distribution resulting from the entanglement with the phonon bath. The decay of the excited state population to the common ground state establishes a non-equilibrium steady-state flux driven by the sunlight, and it defines a time window to observe the transition from dynamical to static coherence. For the parameters relevant to photosynthetic systems, the exciton dynamics initiated by the sunlight exhibits a non-negligible amount of dynamical coherence (quantum beats) on the sub-picosecond timescale; however, this sub-picosecond time-scale is long enough for light-harvesting systems to establish static coherence, which plays a crucial role in efficient energy transfer. Further, a relationship is established between the non-equilibrium steady-state induced by the sunlight and the coherent dynamics initiated from the ground state by a laser $\\delta$-pulse, thereby making a direct connection between incoherent sunlight excitation and ultrafast spectroscopy.

Jan Olšina; Arend G. Dijkstra; Chen Wang; Jianshu Cao

2014-08-21T23:59:59.000Z

406

HELIOS-K: An Ultrafast, Open-source Opacity Calculator for Radiative Transfer  

E-Print Network [OSTI]

We present an ultrafast opacity calculator for application to exoplanetary atmospheres, which we name HELIOS-K. It takes a line list as an input, computes the shape of each spectral line (e.g., a Voigt profile) and provides an option for grouping an enormous number of lines into a manageable number of bins. We implement a combination of Algorithm 916 and Gauss-Hermite quadrature to compute the Voigt profile, write the code in CUDA and optimise the computation for graphics processing units (GPUs). We use the k-distribution method to reduce $\\sim 10^5$ to $10^8$ lines to $\\sim 10$ to $10^4$ wavenumber bins, which may then be used for radiative transfer, atmospheric retrieval and general circulation models. We demonstrate that the resampling of the k-distribution function, within each bin, is an insignificant source of error across a broad range of wavenumbers and column masses. By contrast, the choice of line-wing cutoff for the Voigt profile is a significant source of error and affects the value of the compute...

Grimm, Simon L

2015-01-01T23:59:59.000Z

407

Ultrafast control of donor-bound electron spins with single detuned optical pulses  

E-Print Network [OSTI]

The ability to control spins in semiconductors is important in a variety of fields including spintronics and quantum information processing. Due to the potentially fast dephasing times of spins in the solid state [1-3], spin control operating on the picosecond or faster timescale may be necessary. Such speeds, which are not possible to attain with standard electron spin resonance (ESR) techniques based on microwave sources, can be attained with broadband optical pulses. One promising ultrafast technique utilizes single broadband pulses detuned from resonance in a three-level Lambda system [4]. This attractive technique is robust against optical pulse imperfections and does not require a fixed optical reference phase. Here we demonstrate the principle of coherent manipulation of spins theoretically and experimentally. Using this technique, donor-bound electron spin rotations with single-pulse areas exceeding pi/4 and two-pulses areas exceeding pi/2 are demonstrated. We believe the maximum pulse areas attained do not reflect a fundamental limit of the technique and larger pulse areas could be achieved in other material systems. This technique has applications from basic solid-state ESR spectroscopy to arbitrary single-qubit rotations [4, 5] and bang-bang control[6] for quantum computation.

Kai-Mei C. Fu; Susan M. Clark; Charles Santori; M. C. Holland; Colin R. Stanley; Yoshihisa Yamamoto

2008-06-25T23:59:59.000Z

408

Velocity measurements in the near field of a diesel fuel injector by ultrafast imagery  

E-Print Network [OSTI]

This paper examines the velocity profile of fuel issuing from a high-pressure single-orifice diesel injector. Velocities of liquid structures were determined from time-resolved ultrafast shadow images, formed by an amplified two-pulse laser source coupled to a double-frame camera. A statistical analysis of the data over many injection events was undertaken to map velocities related to spray formation near the nozzle outlet as a function of time after start of injection. These results reveal a strong asymmetry in the liquid profile of the test injector, with distinct fast and slow regions on opposite sides of the orifice. Differences of ~100 m/s can be observed between the 'fast' and 'slow' sides of the jet, resulting in different atomization conditions across the spray. On average, droplets are dispersed at a greater distance from the nozzle on the 'fast' side of the flow, and distinct macrostructure can be observed under the asymmetric velocity conditions. The changes in structural velocity and atomization b...

Sedarsky, David; Blaisot, Jean-Bernard; Rozé, Claude

2013-01-01T23:59:59.000Z

409

Solution Processed MoS2-PVA Composite for Sub-Bandgap Mode-Locking of a Wideband Tunable Ultrafast Er:Fiber Laser  

E-Print Network [OSTI]

with stable, picosecond pulses, tunable from 1535 nm to 1565 nm 2 Solution Processed MoS2-PVA Composite for Sub-Bandgap Mode-Locking of a Wideband Tunable Ultrafast Er:Fiber Laser Meng Zhang1, Richard C. T. Howe2, Robert I. Woodward1... ! to! relaxation! of! thermalized! electron! and!phonon! distribution! [3].! This! combination! of!properties!makes!MoS2!a!suitable!saturable!absorber!(SA)! for! ultrafast! mode+locked! pulsed! lasers,! with!the! potential! for! pulse! generation! at...

Zhang, Meng; Howe, Richard C. T.; Woodward, Robert I.; Kelleher, Edmund J. R.; Torrisi, Felice; Hu, Guohua; Popov, Sergei V.; Taylor, J. Roy; Hasan, Tawfique

2014-11-11T23:59:59.000Z

410

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

SciTech Connect (OSTI)

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

411

Ultrafast and selective coherent population transfer in four-level atoms by a single frequency chirped few-cycle pulse  

E-Print Network [OSTI]

We report and propose a simple scheme to achieve the ultrafast and selective population transfer in four-level atoms by utilizing a single frequency chirped few-cycle pulse. It is demonstrated that the almost complete population may be transferred to the preselected state of atoms just by manipulating the so called chirp offset parameter. The robustness of the scheme against the variation of laser pulse parameters is also investigated. The proposed scheme may also be useful for the selective population transfer in molecules.

Parvendra Kumar; Amarendra K. Sarma

2013-03-01T23:59:59.000Z

412

Ultrafast and efficient coherence creation in ?-like atomic systems driven by nonlinearly chirped few-cycle pulses  

E-Print Network [OSTI]

We report an ultrafast and efficient way to create the maximum coherence between the two lower states in a -like atomic systems, driven by two nonlinearly chirped few-cycle pulses. The phenomenon of coherent population trapping and electromagnetically induced population transfer are investigated by solving the appropriate density matrix equations without invoking the rotating wave approximation. The robustness of the scheme for maximum coherence against the variation of the laser parameters are tested numerically. We also demonstrate that the proposed scheme could be used to obtain complete population transfer to an initially empty ground state.

Amarendra K. Sarma; Parvendra Kumar

2011-11-17T23:59:59.000Z

413

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

SciTech Connect (OSTI)

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

414

Drama in Dynamics: Boom, Splash, and Speed  

SciTech Connect (OSTI)

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

Heather Marie Netzloff

2004-12-19T23:59:59.000Z

415

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

SciTech Connect (OSTI)

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

416

Ultrafast Dynamics of the Low-Lying 3 MLCT States of [Ru(bpy)2(dppp2)]2+  

E-Print Network [OSTI]

in the conversion of photons into electrical and chemical energy in dye-sensitized solar cells and other devices by the dye of a solar cell, typically a mononuclear transition metal complex, is of fundamental importance.1

Turro, Claudia

417

Ultrafast electron beam imaging of femtosecond laser-induced plasma Junjie Li, Xuan Wang, Zhaoyang Chen, Richard Clinite, Samuel S. Mao et al.  

E-Print Network [OSTI]

, Beijing 100190, China and Department of Physics, Shanghai Jiao Tong University, Shanghai 200240, China in the early stage of laser ablation of a copper target are investigated in real time by making ultrafast have been a subject of intensive investigation in recent years ow- ing to its importance in a wide

Cao, Jianming

418

Science Challenge Computational modeling of ultrafast digital electronics To understand how large electric fields, such as those from lightning strikes or electronic countermeasures,  

E-Print Network [OSTI]

properties in response to the needs of a particular device or situation. These smart electronics have the potential to lead to entirely new generations of electronic devices--such as military and civilian Science Challenge ­ Computational modeling of ultrafast digital electronics · To understand how

Freericks, Jim

419

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 infrared heating laser pulse (10 ns)-induced temperature jump. The increases in the fluorescenceVersity of Hong Kong, Shatin N.T., Hong Kong ReceiVed June 4, 2007. In Final Form: July 7, 2007 The heating

Liu, Shilin

420

Transition from ultrafast laser photo-electron emission to space charge limited current in a 1D gap  

E-Print Network [OSTI]

A one-dimensional (1D) model has been constructed to study the transition of the time-dependent ultrafast laser photo-electron emission from a flat metallic surface to the space charge limited (SCL) current, including the effect of non-equilibrium laser heating on metals at the ultrafast time scale. At a high laser field, it is found that the space charge effect cannot be ignored and the SCL current emission is reached at a lower value predicted by a short pulse SCL current model that assumed a time-independent emission process. The threshold of the laser field to reach the SCL regime is determined over a wide range of operating parameters. The calculated results agree well with particle-in-cell (PIC) simulation. It is found that the space charge effect is more important for materials with lower work function like tungsten (4.4 eV) as compared to gold (5.4 eV). However for a flat surface, both materials will reach the space charge limited regime at the sufficiently high laser field such as $>$ 5 GV/m with a laser pulse length of tens to one hundred femtoseconds.

Yangjie Liu; L. K. Ang

2014-08-21T23:59:59.000Z

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.


421

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

SciTech Connect (OSTI)

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

422

Femtosecond diffraction dynamics of laser-induced periodic surface structures on fused silica  

SciTech Connect (OSTI)

The formation of laser-induced periodic surface structures (LIPSS) on fused silica upon irradiation with linearly polarized fs-laser pulses (50 fs pulse duration, 800 nm center wavelength) is studied experimentally using a transillumination femtosecond time-resolved (0.1 ps-1 ns) pump-probe diffraction approach. This allows to reveal the generation dynamics of near-wavelength-sized LIPSS showing a transient diffraction at specific spatial frequencies even before a corresponding permanent surface relief was observed. The results confirm that the ultrafast energy deposition to the materials surface plays a key role and triggers subsequent physical mechanisms such as carrier scattering into self-trapped excitons.

Hoehm, S.; Rosenfeld, A. [Max-Born-Institut fuer Nichtlineare Optik und Kurzzeitspektroskopie (MBI), Max-Born-Strasse 2A, D-12489 Berlin (Germany)] [Max-Born-Institut fuer Nichtlineare Optik und Kurzzeitspektroskopie (MBI), Max-Born-Strasse 2A, D-12489 Berlin (Germany); Krueger, J.; Bonse, J. [BAM Bundesanstalt fuer Materialforschung und - pruefung, Unter den Eichen 87, D-12205 Berlin (Germany)] [BAM Bundesanstalt fuer Materialforschung und - pruefung, Unter den Eichen 87, D-12205 Berlin (Germany)

2013-02-04T23:59:59.000Z

423

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

424

Multiple time step integrators in ab initio molecular dynamics  

SciTech Connect (OSTI)

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

425

Structure and dynamics of aqueous solution of uranyl ions  

SciTech Connect (OSTI)

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

426

Coupled-cluster, Möller Plesset (MP2), Density Fitted Local MP2, and Density Functional Theory Examination of the Energetic and Structural Features of Hydrophobic Solvation: Water and Pentane  

SciTech Connect (OSTI)

The interaction potentials between immiscible polar and non-polar solvents are a major driving force behind the formation of liquid:liquid interfaces. In this work, the interaction energy of water–pentane dimer has been determined using coupled-cluster theory with single double (triple) excitations [CCSD(T)], 2nd order Möller Plesset perturbation theory (MP2), density fitted local MP2 (DF-LMP2), as well as density functional theory using a wide variety of density functionals and several different basis sets. The M05-2X exchange correlation functionals exhibit excellent agreement with CCSD(T) and DF-LMP2 after taking into account basis set superposition error. The gas phase water–pentane interaction energy is found to be quite sensitive to the specific pentane isomer (2,2- dimethylpropane vs. n-pentane) and relative orientation of the monomeric constituents. Subsequent solution phase cluster calculations of 2,2-dimethylpropane and n-pentane solvated by water indicate a positive free energy of solvation that is in good agreement with available experimental data. Structural parameters are quite sensitive to the density functional employed and reflect differences in the two-body interaction energy calculated by each method. In contrast, cluster calculations of pentane solvation of H2O solute are found to be inadequate for describing the organic solvent, likely due to limitations associated with the functionals employed (B3LYP, BHandH, and M05-2X).

Ghadar, Yasaman; Clark, Aurora E.

2012-02-02T23:59:59.000Z

427

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

SciTech Connect (OSTI)

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

428

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

SciTech Connect (OSTI)

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

429

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

SciTech Connect (OSTI)

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

430

Comparative investigation of third- and fifth-harmonic generation in atomic and molecular gases driven by midinfrared ultrafast laser pulses  

SciTech Connect (OSTI)

We report on the comparative experimental investigation on third- and fifth-harmonic generation (THG and FHG) in atomic and molecular gases driven by midinfrared ultrafast laser pulses at a wavelength of {approx}1500 nm. We observe that the conversion efficiencies of both the THG and FHG processes saturate at similar peak intensities close to {approx}1.5 x 10{sup 14} W/cm{sup 2} for argon, nitrogen, and air, whose ionization potentials are close to each other. Near the saturation intensity, the ratio of yields of the FHG and THG reaches {approx}10{sup -1} for all the gases. Our results show that high-order Kerr effect seems to exist; however, contribution from the fourth-order Kerr refractive index coefficient alone is insufficient to balance the Kerr self-focusing without the assistance of plasma generation.

Ni Jielei; Yao Jinping; Zeng Bin; Chu Wei; Li Guihua; Zhang Haisu; Jing Chenrui [State Key Laboratory of High Field Laser Physics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, P.O. Box 800-211, Shanghai 201800 (China); Graduate School of the Chinese Academy of Sciences, Beijing 100039 (China); Chin, S. L. [Department of Physics, Engineering Physics and Optics, and Center for Optics, Photonics and Laser (COPL), Laval University, Laval, Quebec, G1K 7P4 (Canada); Cheng, Y.; Xu, Z. [State Key Laboratory of High Field Laser Physics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, P.O. Box 800-211, Shanghai 201800 (China)

2011-12-15T23:59:59.000Z

431

Electron-ion relaxation time dependent signal enhancement in ultrafast double-pulse laser-induced breakdown spectroscopy  

SciTech Connect (OSTI)

We investigated the emission properties of collinear double-pulse compared to single-pulse ultrafast laser induced breakdown spectroscopy. Our results showed that the significant signal enhancement noticed in the double pulse scheme is strongly correlated to the characteristic electron-ion relaxation time and hence to the inter-pulse delays. Spectroscopic excitation temperature analysis showed that the improvement in signal enhancement is caused by the delayed pulse efficient reheating of the pre-plume. The signal enhancement is also found to be related to the upper excitation energy of the selected lines, i.e., more enhancement noticed for lines originating from higher excitation energy levels, indicating reheating is the major mechanism behind the signal improvement.

Harilal, S. S.; Diwakar, P. K.; 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)

2013-07-22T23:59:59.000Z

432

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

SciTech Connect (OSTI)

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

Fu, Feichao; Liu, Shengguang; Zhu, Pengfei; Xiang, Dao, E-mail: dxiang@sjtu.edu.cn; Zhang, Jie, E-mail: jzhang1@sjtu.edu.cn [Key Laboratory for Laser Plasmas (Ministry of Education), Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240 (China); Cao, Jianming [Department of Physics and National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310 (United States)

2014-08-15T23:59:59.000Z

433

A table-top, repetitive pulsed magnet for nonlinear and ultrafast spectroscopy in high magnetic fields up to 30 T  

SciTech Connect (OSTI)

We have developed a mini-coil pulsed magnet system with direct optical access, ideally suited for nonlinear and ultrafast spectroscopy studies of materials in high magnetic fields up to 30 T. The apparatus consists of a small coil in a liquid nitrogen cryostat coupled with a helium flow cryostat to provide sample temperatures down to below 10 K. Direct optical access to the sample is achieved with the use of easily interchangeable windows separated by a short distance of ?135 mm on either side of the coupled cryostats with numerical apertures of 0.20 and 0.03 for measurements employing the Faraday geometry. As a demonstration, we performed time-resolved and time-integrated photoluminescence measurements as well as transmission measurements on InGaAs quantum wells.

Noe, G. Timothy; Lee, Joseph; Woods, Gary L. [Department of Electrical and Computer Engineering, Rice University, Houston, Texas 77005 (United States)] [Department of Electrical and Computer Engineering, Rice University, Houston, Texas 77005 (United States); Nojiri, Hiroyuki [Institute for Materials Research, Tohoku University, Sendai 980-8577 (Japan)] [Institute for Materials Research, Tohoku University, Sendai 980-8577 (Japan); Léotin, Jean [Laboratoire National des Champs Magnétiques Intenses, CNRS-UJF-UPS-INSA, Toulouse (France)] [Laboratoire National des Champs Magnétiques Intenses, CNRS-UJF-UPS-INSA, Toulouse (France); Kono, Junichiro, E-mail: kono@rice.edu [Department of Electrical and Computer Engineering, Rice University, Houston, Texas 77005 (United States) [Department of Electrical and Computer Engineering, Rice University, Houston, Texas 77005 (United States); Department of Physics and Astronomy, Rice University, Houston, Texas 77005, USA and Department of Materials Science and NanoEngineering, Rice University, Houston, Texas 77005 (United States)

2013-12-15T23:59:59.000Z

434

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

435

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

SciTech Connect (OSTI)

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

436

Industrial Affiliates Day 2006, April 21, 2006 ULTRAFAST NONLINEAR OPTICAL MICROSCOPY  

E-Print Network [OSTI]

of studies, including photochemical reactions, molecular dynamics, micropharmacology and optical memory. History of Two-Photon Molecular Excitation 1905 First Conception: A. Einstein: Creation and Conversion for data storage. Combined with fluorescence microscopy, multiphoton excitation (MPE) provides 3D

Van Stryland, Eric

437

Repetition of the shape of the ultrafast self-modulation of the optical absorption spectrum upon varying the energy of pulse of GaAs pumping  

SciTech Connect (OSTI)

Ultrafast self-modulation of the fundamental optical absorption emerges during intense picosecond optical pumping of GaAs and, according to the main assumption, reflects self-oscillations of depletion of electron populations in the conduction band. In this study, the quantitatively confirmed explanation of previously experimentally found cyclic repetition of the form of ultrafast self-modulation of the absorption spectrum upon varying the energy of the pumping pulse and fixed delay between pumping and probing (the measurement of absorption) is given. Repetition of the shape is explained by varying the phase of self-oscillations of the optical absorption. The explanation is based on the previously found experimentally dependence of the frequency of self-oscillations of absorption on the pumping energy. Therefore, this is also a new confirmation of the mentioned dependence (which satisfactorily coincides with a similar calculated dependence of the frequency of self-oscillations of depletion of populations).

Ageeva, N. N.; Bronevoi, I. L., E-mail: bil@cplire.ru; Zabegaev, D. N.; Krivonosov, A. N. [Russian Academy of Sciences, Kotel'nikov Institute of Radio Engineering and Electronics (Russian Federation)

2010-10-15T23:59:59.000Z

438

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

SciTech Connect (OSTI)

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

439

A dynamic macroscopic quantum oscillator at room temperature  

E-Print Network [OSTI]

We demonstrate a dynamic macroscopic quantum oscillator of a light--matter hybrid state in high-density plasmas created in an optically induced confining potential in a semiconductor microcavity at room temperature. One major advancement is the visualization of quantum oscillator states in a micrometer-scale optical potential at quantized energies up to 4 meV, an order of magnitude higher than that previously observed in spatially confined polariton condensates at cryogenic temperatures. Another advancement is the ability to characterize the time evolution and optical spin polarization of the quantum oscillator states directly from the consequent pulse radiation. The ability to control the macroscopic coherent state of plasma polaritons enables ultrafast multiple pulse lasing in a semiconductor microcavity.

Xie, Wei; Lee, Yi-Shan; Lin, Sheng-Di; Lai, Chih-Wei

2015-01-01T23:59:59.000Z

440

Ab initio studies of ultrafast x-ray scattering of the photodissociation of iodine  

SciTech Connect (OSTI)

We computationally examine various aspects of the reaction dynamics of the photodissociation and recombination of molecular iodine. We use our recently proposed formalism to calculate time-dependent x-ray scattering signal changes from first principles. Different aspects of the dynamics of this prototypical reaction are studied, such as coherent and noncoherent processes, features of structural relaxation that are periodic in time versus nonperiodic dissociative processes, as well as small electron density changes caused by electronic excitation, all with respect to x-ray scattering. We can demonstrate that wide-angle x-ray scattering offers a possibility to study the changes in electron densities in nonperiodic systems, which render it a suitable technique for the investigation of chemical reactions from a structural dynamics point of view.

Debnarova, Andrea; Techert, Simone [Max Planck Institute for Biophysical Chemistry, 37077 Goettingen, Am Fassberg 11 (Germany); Schmatz, Stefan [Institut fuer Physikalische Chemie, Universitaet Goettingen, 37077 Goettingen, Tammannstr. 6 (Germany)

2010-09-28T23:59:59.000Z

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

Fano resonance control in a photonic crystal structure and its application to ultrafast switching  

SciTech Connect (OSTI)

We experimentally demonstrate a photonic crystal structure that allows easy and robust control of the Fano spectrum. Its operation relies on controlling the amplitude of light propagating along one of the light paths in the structure from which the Fano resonance is obtained. Short-pulse dynamic measurements show that besides drastically increasing the switching contrast, the transmission dynamics itself is strongly affected by the nature of the resonance. The influence of slow-recovery tails implied by a long carrier lifetime can thus be reduced using a Fano resonance due to a hitherto unrecognized reshaping effect of the nonlinear Fano transfer function. As an example, we present a system application of a Fano structure, demonstrating its advantages by the experimental realization of 10 Gbit/s all-optical modulation with optical control power less than 1?mW.

Yu, Yi, E-mail: yiyu@fotonik.dtu.dk; Heuck, Mikkel; Hu, Hao; Xue, Weiqi; Peucheret, Christophe; Chen, Yaohui; Oxenløwe, Leif Katsuo; Yvind, Kresten; Mørk, Jesper [DTU Fotonik, Technical University of Denmark, DK-2800 Kongens Lyngby (Denmark)

2014-08-11T23:59:59.000Z

442

Gain dynamics of quantum dot devices for dual-state operation  

SciTech Connect (OSTI)

Ground state gain dynamics of In(Ga)As-quantum dot excited state lasers are investigated via single-color ultrafast pump-probe spectroscopy below and above lasing threshold. Two-color pump-probe experiments are used to localize lasing and non-lasing quantum dots within the inhomogeneously broadened ground state. Single-color results yield similar gain recovery rates of the ground state for lasing and non-lasing quantum dots decreasing from 6 ps to 2 ps with increasing injection current. We find that ground state gain dynamics are influenced solely by the injection current and unaffected by laser operation of the excited state. This independence is promising for dual-state operation schemes in quantum dot based optoelectronic devices.

Kaptan, Y., E-mail: yuecel.kaptan@physik.tu-berlin.de; Herzog, B.; Kolarczik, M.; Owschimikow, N.; Woggon, U. [Institut für Optik und Atomare Physik, Technische Universität Berlin, Berlin (Germany); Schmeckebier, H.; Arsenijevi?, D.; Bimberg, D. [Institut für Festkörperphysik, Technische Universität Berlin, Berlin (Germany); Mikhelashvili, V.; Eisenstein, G. [Technion Institute of Technology, Faculty of Electrical Engineering, Haifa (Israel)

2014-06-30T23:59:59.000Z

443

Ultrafast photon-photon interaction in a strongly coupled quantum dot-cavity system  

E-Print Network [OSTI]

We study dynamics of the interaction between two weak light beams mediated by a strongly coupled quantum dot-photonic crystal cavity system. First, we perform all optical switching of a weak continuous-wave signal with a pulsed control beam, and then perform switching between two pulsed beams (40ps pulses) at the single photon level. Our results show that the quantum dot-nanocavity system creates strong, controllable interactions at the single photon level.

Dirk Englund; Arka Majumdar; Michal Bajcsy; Andrei Faraon; Pierre Petroff; Jelena vuckovic

2011-07-14T23:59:59.000Z

444

Magnetically-Driven Accretion-Disk Winds and Ultra-Fast Outflows in PG1211+143  

E-Print Network [OSTI]

We present a study of X-ray ionization of magnetohydrodynamic (MHD) accretion-disk winds in an effort to constrain the physics underlying the highly-ionized ultra-fast outflows (UFOs) inferred by X-ray absorbers often detected in various sub-classes of Seyfert active galactic nuclei (AGNs). Our primary focus is to show that magnetically-driven outflows are indeed physically plausible candidates for the observed outflows accounting for the AGN absorption properties of the present X-ray spectroscopic observations. Employing a stratified MHD wind launched across the entire AGN accretion disk, we calculate its X-ray ionization and the ensuing X-ray absorption line spectra. Assuming an appropriate ionizing AGN spectrum, we apply our MHD winds to model the absorption features in an {\\it XMM-Newton}/EPIC spectrum of the narrow-line Seyfert, \\pg. We find, through identifying the detected features with Fe K$\\alpha$ transitions, that the absorber has a characteristic ionization parameter of $\\log (\\xi_c [erg~cm~s$^{-1}...

Fukumura, Keigo; Kazanas, Demosthenes; Shrader, Chris; Behar, Ehud; Contopoulos, Ioannis

2015-01-01T23:59:59.000Z

445

A simple electron time-of-flight spectrometer for ultrafast vacuum ultraviolet photoelectron spectroscopy of liquid solutions  

SciTech Connect (OSTI)

We present a simple electron time of flight spectrometer for time resolved photoelectron spectroscopy of liquid samples using a vacuum ultraviolet (VUV) source produced by high-harmonic generation. The field free spectrometer coupled with the time-preserving monochromator for the VUV at the Artemis facility of the Rutherford Appleton Laboratory achieves an energy resolution of 0.65 eV at 40 eV with a sub 100 fs temporal resolution. A key feature of the design is a differentially pumped drift tube allowing a microliquid jet to be aligned and started at ambient atmosphere while preserving a pressure of 10{sup ?1} mbar at the micro channel plate detector. The pumping requirements for photoelectron (PE) spectroscopy in vacuum are presented, while the instrument performance is demonstrated with PE spectra of salt solutions in water. The capability of the instrument for time resolved measurements is demonstrated by observing the ultrafast (50 fs) vibrational excitation of water leading to temporary proton transfer.

Arrell, C. A., E-mail: christopher.arrell@epfl.ch; Ojeda, J.; Mourik, F. van; Chergui, M. [Laboratory of Ultrafast Spectroscopy, ISIC, Station 6, Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne (Switzerland); Sabbar, M.; Gallmann, L.; Keller, U. [Physics Department, ETH Zurich, 8093 Zurich (Switzerland); Okell, W. A.; Witting, T.; Siegel, T.; Diveki, Z.; Hutchinson, S.; Tisch, J. W.G.; Marangos, J. P. [Department of Physics, The Blackett Laboratory, Imperial College, London SW7 2AZ (United Kingdom); Chapman, R. T.; Cacho, C.; Rodrigues, N.; Turcu, I. C.E.; Springate, E. [Central Laser Facility, STFC Rutherford Appleton Laboratory, Oxon OX11 0QX (United Kingdom)

2014-10-15T23:59:59.000Z

446

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

SciTech Connect (OSTI)

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

447

Ultrafast Large Area Micropattern Generation in Non-absorbing Polymer Thin-Films by Pulsed Laser Diffraction  

E-Print Network [OSTI]

We report an ultrafast, parallel and beyond-the-master micro-patterning technique for ultrathin (30 nm-400 nm) non-absorbing polymer films by diffraction of a laser light through a two dimensional periodic aperture. The redistribution of laser energy absorbed by the substrate causes self-organization of polymer thin-film in the form of wrinkle like surface relief structures caused by localized melting and freezing of the thin-film. Unlike the conventional laser ablation and laser writing processes, low laser fluence is employed to only passively swell the polymer as a pre-ablative process without the loss of material, and without absorption/reaction with the incident radiation. Self-organization in the thin polymer film aided by the diffraction pattern produces micro-structures made up of thin raised lines. These regular microstructures have far more complex morphologies than the mask geometry and very narrow line widths that can be an order of magnitude smaller than the openings in the mask. The microstructure morphology is easily modulated by changing the film thickness, aperture size and geometry and by changing the diffraction pattern, e.g., by changing the aperture-substrate distance.

Ankur Verma; Ashutosh Sharma; Giridhar U. Kulkarni

2011-01-27T23:59:59.000Z

448

NuSTAR Reveals Relativistic Reflection But No Ultra-Fast Outflow In The Quasar PG 1211+143  

E-Print Network [OSTI]

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

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

2015-01-01T23:59:59.000Z

449

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

SciTech Connect (OSTI)

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

450

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

SciTech Connect (OSTI)

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

451

Why do mixed quantum-classical methods describe short-time dynamics through conical intersections so well? Analysis of geometric phase effects  

E-Print Network [OSTI]

Adequate simulation of non-adiabatic dynamics through conical intersection requires account for a non-trivial geometric phase (GP) emerging in electronic and nuclear wave-functions in the adiabatic representation. Popular mixed quantum-classical (MQC) methods, surface hopping and Ehrenfest, do not carry a nuclear wave-function to be able to incorporate the GP into nuclear dynamics. Surprisingly, the MQC methods reproduce ultra-fast interstate crossing dynamics generated with the exact quantum propagation so well as if they contained information about the GP. Using two-dimensional linear vibronic coupling models we unravel how the MQC methods can effectively mimic the most significant dynamical GP effects: 1) compensation for repulsive diagonal second order non-adiabatic couplings and 2) transfer enhancement for a fully cylindrically symmetric component of a nuclear distribution.

Gherib, Rami; Izmaylov, Artur F

2015-01-01T23:59:59.000Z

452

Nonlinear Ultrafast Spectroscopy of Electron and Energy Transfer in Molecule Complexes  

SciTech Connect (OSTI)

The proposed research program will focus on the development of a unified dynamical theoretical framework for calculating the optical response of molecular assemblies and applying it towards studying the interplay of energy and charge transfer in artificial chromophore-aggregate complexes. Applications will be made to poly (p phenylene vinylene), (PPV) oligomers, several families of stilbenoid aggregates with stacking through a cyclophane group, coupled porphyrin arrays, and energy funneling in phenylacetylene dendrimers. The approach is based on formulating the problem using the density- matrix and developing Liouville-space techniques which provide physical insight and are particularly suitable for computing both coherent and incoherent transport. A physical picture based on collective electronic normal modes which represent the dynamics of the optically-driven reduced single electron density matrix will be established. Femtosecond signals and optical properties will be directly related to the motions of electron-hole pairs in real space, completely avoiding the calculation of many-electron excited-state wavefunctions, thus, considerably reducing computational effort. Vibrational and solvent effects will be incorporated. Guidelines for the synthesis of new donor/bridge/acceptor molecules with desired properties such as carrier transport, optical response time scales and fluorescence quantum yields will be developed. The analogy with Thz emission spectroscopy which probes charge carrier dynamic is in semiconductor superlattices will be explored. A systematic procedure for identifying the electronic coherence sizes which control the transport and optical properties will be developed. Localization of electronic transition density matrices of large molecules will be used to break the description of their optical response into coupled chromophores. The proposal is divided into four parts: (i) Collective-Oscillator Representation of Electronic Excitations in Molecular Assemblies; (ii) Nonlinear Optical Spectroscopy of Coupled Chromophores; (iii) Long-Range Electron Transfer and Transport in Solvents with Complex Spectral Densities; (iv) Probing Exciton-Migration by Coherent Femtosecond Spectroscopies.

Mukamel, Shaul

2006-02-09T23:59:59.000Z

453

Ultrafast coherent control of angular momentum during a one-photon excitation  

SciTech Connect (OSTI)

The subpicosecond dynamics of angular momentum transfer in the excited rubidium 5p state is studied in real time by observing photoelectron angular distributions with velocity map imaging. Retrieving the populations of the degenerate Zeeman levels and reconstructing the angular momentum, we show that in the case of resonant excitation the angular momentum does not follow the momentary helicity of the electric field of the pulse. This is in contrast with off-resonant excitation where the angular momentum and pulse helicity are fully correlated. Our study shows how to generate and shape ultrashort pulses of orbital and spin angular momentum in a controllable way.

Malik, D. A.; Eppink, A. T. J. B.; Meerts, W. L.; Kimel, A. V.; Kirilyuk, A.; Rasing, Th.; Zande, W. J. van der [Radboud University Nijmegen, Institute for Molecules and Materials, P.O. Box 9010, NL-6500 GL Nijmegen (Netherlands)

2011-10-15T23:59:59.000Z

454

Development of Nanofluidic Cells for Ultrafast X-ray Studies of Water  

SciTech Connect (OSTI)

In order to study the molecular structure and dynamics of liquid water with soft x-ray probes, samples with nanoscale dimensions are needed. This paper describes a simple method for preparing nanofluidic water cells. The idea is to confine a thin layer of water between two silicon nitride windows. The windows are 1 mm x 1 mm and 0.5 mm x 0.5 mm in size and have a thickness of 150 nm. The thickness of the water layer was measured experimentally by probing the infrared spectrum of water in the cells with a Fourier Transform InfraRed (FTIR) apparatus and from soft x-ray static measurements at the Advanced Light Source (ALS) at Lawrence Berkeley National Laboratory. Water layers ranging from 10 nm to more than 2 {micro}m were observed. Evidence for changes in the water structure compared to bulk water is observed in the ultrathin cells.

Irizarry, Melvin E.; /Puerto Rico U., Mayaguez /SLAC

2006-08-23T23:59:59.000Z

455

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

456

Femtosecond time-resolved photoemission electron microscopy for spatiotemporal imaging of photogenerated carrier dynamics in semiconductors  

SciTech Connect (OSTI)

We constructed an instrument for time-resolved photoemission electron microscopy (TR-PEEM) utilizing femtosecond (fs) laser pulses to visualize the dynamics of photogenerated electrons in semiconductors on ultrasmall and ultrafast scales. The spatial distribution of the excited electrons and their relaxation and/or recombination processes were imaged by the proposed TR-PEEM method with a spatial resolution about 100 nm and an ultrafast temporal resolution defined by the cross-correlation of the fs laser pulses (240 fs). A direct observation of the dynamical behavior of electrons on higher resistivity samples, such as semiconductors, by TR-PEEM has still been facing difficulties because of space and/or sample charging effects originating from the high photon flux of the ultrashort pulsed laser utilized for the photoemission process. Here, a regenerative amplified fs laser with a widely tunable repetition rate has been utilized, and with careful optimization of laser parameters, such as fluence and repetition rate, and consideration for carrier lifetimes, the electron dynamics in semiconductors were visualized. For demonstrating our newly developed TR-PEEM method, the photogenerated carrier lifetimes around a nanoscale defect on a GaAs surface were observed. The obtained lifetimes were on a sub-picosecond time scale, which is much shorter than the lifetimes of carriers observed in the non-defective surrounding regions. Our findings are consistent with the fact that structural defects induce mid-gap states in the forbidden band, and that the electrons captured in these states promptly relax into the ground state.

Fukumoto, Keiki, E-mail: fukumoto.k.ab@m.titech.ac.jp; Yamada, Yuki; Matsuki, Takashi; Koshihara, Shin-ya [Department of Materials Science, Tokyo Institute of Technology, Oookayama, Meguro-ku, Tokyo 152-8550 (Japan); Japan Science and Technology Agency JST-CREST, Honcho, Kawaguchi, Saitama 332-0012 (Japan); Onda, Ken [Interactive Research Center of Science, Tokyo Institute of Technology, Nagatsuta, Midori-ku, Yokohama 226-8502 (Japan); Japan Science and Technology Agency JST-PRESTO, Honcho, Kawaguchi, Saitama 332-0012 (Japan); Mukuta, Tatsuhiko; Tanaka, Sei-ichi [Department of Materials Science, Tokyo Institute of Technology, Oookayama, Meguro-ku, Tokyo 152-8550 (Japan)

2014-08-15T23:59:59.000Z

457

Complex Dynamics  

E-Print Network [OSTI]

Complex Dynamics Bernardo Da Costa, Koushik Ramachandran, Jingjing Qu, and I had a two semester learning seminar in complex analysis and potential ...

458

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

SciTech Connect (OSTI)

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

459

Theory of ultrafast photoinduced electron transfer from a bulk semiconductor to a quantum dot  

SciTech Connect (OSTI)

This paper describes analytical and numerical results from a model Hamiltonian method applied to electron transfer (ET) from a quasicontinuum (QC) of states to a set of discrete states, with and without a mediating bridge. Analysis of the factors that determine ET dynamics yields guidelines for achieving high-yield electron transfer in these systems, desired for instance for applications in heterogeneous catalysis. These include the choice of parameters of the laser pulse that excites the initial state into a continuum electronic wavepacket and the design of the coupling between the bridge molecule and the donor and acceptor. The vibrational mode on a bridging molecule between donor and acceptor has an influence on the yield of electron transfer via Franck-Condon factors, even in cases where excited vibrational states are only transiently populated. Laser-induced coherence of the initial state as well as energetic overlap is crucial in determining the ET yield from a QC to a discrete state, whereas the ET time is influenced by competing factors from the coupling strength and the coherence properties of the electronic wavepacket.

Rasmussen, Andrew M., E-mail: andyras@gmail.com; Ramakrishna, S.; Weiss, Emily A.; Seideman, Tamar, E-mail: t-seideman@northwestern.edu [Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3113 (United States)] [Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3113 (United States)

2014-04-14T23:59:59.000Z

460

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

SciTech Connect (OSTI)

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

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

Biosystem Dynamics & Design | EMSL  

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

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

462

Dielectric Boundary in Biomolecular Solvation  

E-Print Network [OSTI]

solute solvent solute Biomolecular Modeling: Explicit vs. Implicit MD simulations Statistical mechanics. Dzubiella, Swanson, & McCammon: PRL, 2006; JCP, 2006. Free-energy functional ri m Qi w c j , q j (Zhejiang Univ.) Funding: NIH, NSF, and CTBP #12;5 0 - B'() = -f B() = -1 c j e -q j -1( )j=1 M ri m

Li, Bo

463

Models for solvated biomolecular structures  

E-Print Network [OSTI]

Point Charge / Extended (SPC/E) [15] [100] and Transferableexplicit water models). In both SPC/E and TIP3P, the siteearlier, models such as TIP3P and SPC/E describe water in a

Cerutti, David

2007-01-01T23:59:59.000Z

464

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

465

Dynamics of Confined Water Molecules in Aqueous Salt Hydrates  

SciTech Connect (OSTI)

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

466

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

467

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.

468

7216 J. Phys. Chem. 1993,97, 7216-7221 Ultrafast Electronic Deactivation and Vibrational Dynamics of Photoexcited Uranium(IV)  

E-Print Network [OSTI]

of Photoexcited Uranium(IV) Porphyrin Sandwich Complexes Osman Bilse1,t Stanley N. Milam,* Gregory S. Girolami,***Kenneth S. Suslick,*dand Dewey Holten**+ Department of Chemistry, WashingtonUniversity, St. Louis, Missouri

Girolami, Gregory S.

469

Excited State Structural Dynamics of Carotenoids and ChargeTransfer Systems  

SciTech Connect (OSTI)

This dissertation describes the development andimplementation of a visible/near infrared pump/mid-infrared probeapparatus. Chapter 1 describes the background and motivation ofinvestigating optically induced structural dynamics, paying specificattention to solvation and the excitation selection rules of highlysymmetric molecules such as carotenoids. Chapter 2 describes thedevelopment and construction of the experimental apparatus usedthroughout the remainder of this dissertation. Chapter 3 will discuss theinvestigation of DCM, a laser dye with a fluorescence signal resultingfrom a charge transfer state. By studying the dynamics of DCM and of itsmethyl deuterated isotopomer (an otherwise identical molecule), we areable to investigate the origins of the charge transfer state and provideevidence that it is of the controversial twisted intramolecular (TICT)type. Chapter 4 introduces the use of two-photon excitation to the S1state, combined with one-photon excitation to the S2 state of thecarotenoid beta-apo-8'-carotenal. These 2 investigations show evidencefor the formation of solitons, previously unobserved in molecular systemsand found only in conducting polymers Chapter 5 presents an investigationof the excited state dynamics of peridinin, the carotenoid responsiblefor the light harvesting of dinoflagellates. This investigation allowsfor a more detailed understanding of the importance of structuraldynamics of carotenoids in light harvesting.

Van Tassle, Aaron Justin

2006-09-01T23:59:59.000Z

470

Update on Electrolyte Modeling with Emphasis on Low Temperature...  

Energy Savers [EERE]

performance) Molecular dynamics simulation studies of electrolytes and electrolyteelectrode interfaces Linking Ion Solvation and Lithium Battery Electrolyte Properties...

471

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

472

VOLUME 87, NUMBER 8 P H Y S I C A L R E V I E W L E T T E R S 20 AUGUST 2001 Investigation of Ultrafast Laser-Driven Radiative Blast Waves  

E-Print Network [OSTI]

. This is believed to be due to the stabilizing effect of a relatively thick blast wave shell resulting in part from of Ultrafast Laser-Driven Radiative Blast Waves M.J. Edwards,1 A. J. MacKinnon,1 J. Zweiback,1 K. Shigemori,2 D blast waves produced by the deposition of femtosecond laser pulses in gas jets. In high-Z gases

Ditmire, Todd

473

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

474

Coherent exciton dynamics in the presence of underdamped vibrations  

E-Print Network [OSTI]

Recent ultrafast optical experiments show that excitons in large biological light-harvesting complexes are coupled to molecular vibration modes. These high-frequency vibrations will not only affect the optical response, but also drive the exciton transport. Here, using a model dimer system, the frequency of the underdamped vibration is shown to have a strong effect on the exciton dynamics such that quantum coherent oscillations in the system can be present even in the case of strong noise. Two mechanisms are identified to be responsible for the enhanced transport efficiency: critical damping due to the tunable effective strength of the coupling to the bath, and resonance coupling where the vibrational frequency coincides with the energy gap in the system. The interplay of these two mechanisms determines parameters responsible for the most efficient transport, and these optimal control parameters are comparable to those in realistic light-harvesting complexes. Interestingly, oscillations in the excitonic coherence at resonance are suppressed in comparison to the case of an off-resonant vibration.

Arend G. Dijkstra; Chen Wang; Jianshu Cao; Graham R. Fleming

2014-12-22T23:59:59.000Z

475

Flavor Dynamics  

E-Print Network [OSTI]

The purpose of BRAHMS is to survey the dynamics of relativistic heavy ion (as well as pp and d-A) collisions over a very wide range of rapidity and transverse momentum. The sum of these data may give us a glimpse of the initial state of the system, its transverse and longitudinal evolution and how the nature of the system changes with time. Here I will concentrate on the origin and dynamics of the light flavors, i.e. the creation and transport of the up, down and strange quarks. The results presented here are certainly not the end of the story. It is my hope that in a few years new detectors will reveal the rapidity dependence of the charm and bottom quarks.

Michael Murray; for the BRAHMS Collaboration

2007-10-24T23:59:59.000Z

476

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

SciTech Connect (OSTI)

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

Zwier, Timothy

2012-07-20T23:59:59.000Z

477

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

478

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

SciTech Connect (OSTI)

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

479

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

SciTech Connect (OSTI)

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

480

Femtosecond laser diagnostics of the built-in electric field across the p{sup +}-Si/SiO{sub 2} interface and its ultrafast shielding  

SciTech Connect (OSTI)

Ultrafast shielding of the built-in electric field E{sub 0} across the p{sup +}-Si/SiO{sub 2} interface of boron doped Si upon near infrared femtosecond (fs) laser pulse irradiation (73 {+-} 5 fs, 35 GW/cm{sup 2}{<=} I{sub peak}{sup ({omega})} {<=} 115 GW/cm{sup 2}) is shown to be dominated by electron-hole (e-h) pairs generated via two-photon absorption (TPA), whereas contributions from one-photon absorption (OPA) appear negligible. E{sub 0} shows up in the instantaneous signal I{sup (2{omega})}(t Almost-Equal-To 0) Almost-Equal-To I{sup (2{omega})}(E{sub 0}) of the Electric Field Induced Second Harmonic (EFISH). Its power law is derived from the linear log I{sup (2{omega})}(E{sub 0}) vs. log (I{sub peak}{sup ({omega})}){sup n} plots of six fs laser wavelengths 741.2 nm {<=} {lambda} {<=} 801.0 nm for the first time. These reveal 1.2 {<=} n({lambda}) {<=} 2.1 with the minimum at {lambda} = 752.4 nm (2h{nu} = 3.3 eV) related to resonantly enhanced TPA. Shielding of E{sub 0} by e-h pairs from OPA cannot be detected by EFISH in the same fs laser pulse as their generation requires relatively slow electron-phonon coupling.

Neethling, P. H.; Rohwer, E. G. [Laser Research Institute, Physics Department, University of Stellenbosch, Private Bag X1, Matieland 7602 (South Africa)] [Laser Research Institute, Physics Department, University of Stellenbosch, Private Bag X1, Matieland 7602 (South Africa); Stafast, H. [Laser Research Institute, Physics Department, University of Stellenbosch, Private Bag X1, Matieland 7602 (South Africa) [Laser Research Institute, Physics Department, University of Stellenbosch, Private Bag X1, Matieland 7602 (South Africa); Institute of Photonic Technology (IPHT), POB 100239, D-07702 Jena, Germany and Faculty of Physics and Astronomy, Friedrich Schiller University, Jena (Germany)

2013-06-14T23:59:59.000Z