Sample records for ultrafast solvation dynamics

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

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

    Ultrafast X-Ray Spectroscopy as a Probe of Nonequilibrium Dynamics in Ruthenium Complexes The Electronic Origin of Photoinduced Strain Modifying Proteins to Combat Disease Higher...

  2. Solvation!

    SciTech Connect (OSTI)

    Ivana Adamovic

    2004-12-19T23:59:59.000Z

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

  3. Ultrafast studies of solution dynamics

    SciTech Connect (OSTI)

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

    1997-10-01T23:59:59.000Z

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

  4. Ultrafast dynamic ellipsometry of laser driven shock waves

    E-Print Network [OSTI]

    Bolme, Cynthia Anne

    2008-01-01T23:59:59.000Z

    The experimental measurement technique of ultrafast dynamic ellipsometry (UDE) was developed for measuring material motion and changes in optical properties of samples under laser driven shock loading. Ultrafast dynamic ...

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

    E-Print Network [OSTI]

    Peinke, Joachim

    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

  6. Ultrafast Core-Hole Induced Dynamics in Water

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

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

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

    E-Print Network [OSTI]

    Bogatko, Stuart A.

    2008-01-01T23:59:59.000Z

    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+

  8. Structural Dynamics of a Catalytic Monolayer Probed by Ultrafast

    E-Print Network [OSTI]

    Fayer, Michael D.

    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

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

    E-Print Network [OSTI]

    Peinke, Joachim

    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

  10. Ultrafast Magnetism Dynamics Measure Using Tabletop Ultrafast EUV Sources

    SciTech Connect (OSTI)

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

    2013-08-21T23:59:59.000Z

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

  11. Ultrafast dynamic ellipsometry and spectroscopy of laser shocked materials

    SciTech Connect (OSTI)

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

    2011-01-20T23:59:59.000Z

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

  12. Ultrafast dynamics of excitons in tetracene single crystals

    SciTech Connect (OSTI)

    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

    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.

  13. Ultrafast X-Ray Spectroscopy as a Probe of Nonequilibrium Dynamics...

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

    dynamic broadenings, and changes in the branching ratio. The authors demonstrate that ultrafast x-ray spectroscopy is a suitable probe to deliver detailed new insights or...

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

    E-Print Network [OSTI]

    Fayer, Michael D.

    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

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

    E-Print Network [OSTI]

    Mazur, Eric

    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

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

    E-Print Network [OSTI]

    Nolte, David D.

    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

  17. Optical Nonlinearities and Ultrafast Carrier Dynamics in Semiconductor Quantum Dots

    SciTech Connect (OSTI)

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

    1998-08-10T23:59:59.000Z

    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.

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

    E-Print Network [OSTI]

    Fayer, Michael D.

    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 (

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

    E-Print Network [OSTI]

    Mazur, Eric

    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

  20. Ultrafast Dynamics of 1,3-Cyclohexadiene in Highly Excited States

    E-Print Network [OSTI]

    Minitti, Michael P.

    2011-01-01T23:59:59.000Z

    The ultrafast dynamics of 1,3-cyclohexadiene has been investigated via structurally sensitive Rydberg electron binding energies and shown to differ upon excitation to the 1B state and the 3p Rydberg state. Excitation of ...

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

    SciTech Connect (OSTI)

    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

    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.

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

    E-Print Network [OSTI]

    Fayer, Michael D.

    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

  3. Dynamics of the folded and unfolded villin headpiece (HP35) measured with ultrafast

    E-Print Network [OSTI]

    Fayer, Michael D.

    Dynamics of the folded and unfolded villin headpiece (HP35) measured with ultrafast 2D IR in the folded configuration. The dynamics of the folded HP35-ðCNÞ2 are compared to that of the guanidine to differentiate the peptide dynamic contributions to the observables from those of the water solvent. Because

  4. Ultrafast Structural Dynamics in Combustion Relevant Model Systems

    SciTech Connect (OSTI)

    Weber, Peter M. [Brown University

    2014-03-31T23:59:59.000Z

    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

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

    E-Print Network [OSTI]

    Fayer, Michael D.

    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

  6. Neuroglobin dynamics observed with ultrafast 2D-IR vibrational echo spectroscopy

    E-Print Network [OSTI]

    Fayer, Michael D.

    Neuroglobin dynamics observed with ultrafast 2D-IR vibrational echo spectroscopy Haruto Ishikawa Contributed by Michael D. Fayer, August 15, 2007 (sent for review July 25, 2007) Neuroglobin (Ngb), a protein energy minimum. myoglobin mutants protein dynamics energy landscape Neuroglobin (Ngb) is a recently

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

    SciTech Connect (OSTI)

    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

    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.

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

    SciTech Connect (OSTI)

    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

    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.

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

    SciTech Connect (OSTI)

    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

    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.

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

    E-Print Network [OSTI]

    Yang, H.

    2011-01-01T23:59:59.000Z

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

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

    E-Print Network [OSTI]

    Fayer, Michael D.

    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

  12. Dynamics of Hemoglobin in Human Erythrocytes and in Solution: Influence of Viscosity Studied by Ultrafast

    E-Print Network [OSTI]

    Fayer, Michael D.

    Dynamics of Hemoglobin in Human Erythrocytes and in Solution: Influence of Viscosity Studied by Ultrafast Vibrational Echo Experiments Brian L. McClain, Ilya J. Finkelstein, and M. D. Fayer* Contribution experiments are used to measure the vibrational dephasing of the CO stretching mode of hemoglobin-CO (Hb

  13. 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

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

    E-Print Network [OSTI]

    Hosler, Erik Robert

    2013-01-01T23:59:59.000Z

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

  15. 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: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level:Energy: Grid Integration Redefining What'sis Taking Over OurThe Iron Spin TransitionProgram |Frank CasellaEnergyUltracold Atoms: HowUltrafast

  16. 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: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level:Energy: Grid Integration Redefining What'sis Taking Over OurThe Iron Spin TransitionProgram |Frank CasellaEnergyUltracold Atoms:Ultrafast

  17. 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: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645U.S. DOE Office of ScienceandMesa del SolStrengthening aTurbulence may bedieselsummerFact SheetsUltrafast Core-Hole

  18. 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: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645U.S. DOE Office of ScienceandMesa del SolStrengthening aTurbulence may bedieselsummerFact SheetsUltrafast

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

    E-Print Network [OSTI]

    Perera, Lalith

    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

  20. Analysis of the Ultra-fast Switching Dynamics in a Hybrid MOSFET/Driver

    SciTech Connect (OSTI)

    Tang, T.; Burkhart, C.; /SLAC

    2011-08-17T23:59:59.000Z

    The turn-on dynamics of a power MOSFET during ultra-fast, {approx} ns, switching are discussed in this paper. The testing was performed using a custom hybrid MOSFET/Driver module, which was fabricated by directly assembling die-form components, power MOSFET and drivers, on a printed circuit board. By using die-form components, the hybrid approach substantially reduces parasitic inductance, which facilitates ultra-fast switching. The measured turn on time of the hybrid module with a resistive load is 1.2 ns with an applied voltage of 1000 V and drain current of 33 A. Detailed analysis of the switching waveforms reveals that switching behavior must be interpreted differently in the ultra-fast regime. For example, the gate threshold voltage to turn on the device is observed to increase as the switching time decreases. Further analysis and simulation of MOSFET switching behavior shows that the minimum turn on time scales with the product of the drain-source on resistance and drain-source capacitance, R{sub DS(on)}C{sub OSS}. This information will be useful in power MOSFET selection and gate driver design for ultra-fast switching applications.

  1. Wavelet analysis of molecular dynamics: Efficient extraction of time-frequency information in ultrafast optical processes

    SciTech Connect (OSTI)

    Prior, Javier; Castro, Enrique [Departamento de Física Aplicada, Universidad Politécnica de Cartagena, Cartagena 30202 (Spain)] [Departamento de Física Aplicada, Universidad Politécnica de Cartagena, Cartagena 30202 (Spain); Chin, Alex W. [Theory of Condensed Matter Group, University of Cambridge, J J Thomson Avenue, Cambridge CB3 0HE (United Kingdom)] [Theory of Condensed Matter Group, University of Cambridge, J J Thomson Avenue, Cambridge CB3 0HE (United Kingdom); Almeida, Javier; Huelga, Susana F.; Plenio, Martin B. [Institut für Theoretische Physik, Albert-Einstein-Allee 11, Universität Ulm, D-89069 Ulm (Germany)] [Institut für Theoretische Physik, Albert-Einstein-Allee 11, Universität Ulm, D-89069 Ulm (Germany)

    2013-12-14T23:59:59.000Z

    New experimental techniques based on nonlinear ultrafast spectroscopies have been developed over the last few years, and have been demonstrated to provide powerful probes of quantum dynamics in different types of molecular aggregates, including both natural and artificial light harvesting complexes. Fourier transform-based spectroscopies have been particularly successful, yet “complete” spectral information normally necessitates the loss of all information on the temporal sequence of events in a signal. This information though is particularly important in transient or multi-stage processes, in which the spectral decomposition of the data evolves in time. By going through several examples of ultrafast quantum dynamics, we demonstrate that the use of wavelets provide an efficient and accurate way to simultaneously acquire both temporal and frequency information about a signal, and argue that this greatly aids the elucidation and interpretation of physical process responsible for non-stationary spectroscopic features, such as those encountered in coherent excitonic energy transport.

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

    SciTech Connect (OSTI)

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

    2007-09-01T23:59:59.000Z

    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.

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

    E-Print Network [OSTI]

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

    2007-01-12T23:59:59.000Z

    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.

  4. 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]

    Weston, Ken

    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

  5. Ultrafast magnetization dynamics in diluted magnetic semiconductors This article has been downloaded from IOPscience. Please scroll down to see the full text article.

    E-Print Network [OSTI]

    Boyer, Edmond

    Ultrafast magnetization dynamics in diluted magnetic semiconductors This article has been of Physics Ultrafast magnetization dynamics in diluted magnetic semiconductors O Morandi1,3 , P-A Hervieux2 of the magnetization in diluted magnetic semiconductor quantum wells after weak laser excitation. Based on the pseudo

  6. Ultrafast reaction dynamics in cluster ions: Simulation of the transient photoelectron spectrum of I2 Arn photodissociation

    E-Print Network [OSTI]

    Faeder, Jim

    Hamiltonian model of electronic structure with nonadiabatic molecular dynamics simulations, we calculate of the electronic structure of a manifold of states strongly coupled to the many solvent degrees of freedomUltrafast reaction dynamics in cluster ions: Simulation of the transient photoelectron spectrum

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

    SciTech Connect (OSTI)

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

    2009-03-26T23:59:59.000Z

    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.

  8. Stabilized Ultrafast Pulse Generation and Optical Frequency Combs Techniques

    E-Print Network [OSTI]

    Van Stryland, Eric

    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

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

    E-Print Network [OSTI]

    Boxer, Steven G.

    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

  10. Evidence for Conical Intersection Dynamics Mediating Ultrafast Singlet Exciton Fission

    E-Print Network [OSTI]

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

    2015-01-01T23:59:59.000Z

    -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...

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

    E-Print Network [OSTI]

    Röder, Beate

    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

  12. Ultrafast dynamics of strongly coupled quantum dot-nanocavity systems

    E-Print Network [OSTI]

    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

    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.

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

    SciTech Connect (OSTI)

    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

    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.

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

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

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

  15. Dynamics of the plumes produced by ultrafast laser ablation of metals

    SciTech Connect (OSTI)

    Donnelly, T.; Lunney, J. G. [School of Physics, Trinity College Dublin, Dublin 2 (Ireland); Amoruso, S.; Bruzzese, R.; Wang, X. [Dipartimento di Scienze Fisiche and CNR-SPIN, Universita degli Studi di Napoli Federico II, Complesso Universitario di Monte S. Angelo, Via Cintia, I-80126 Napoli (Italy); Ni, X. [Department of Electronic Engineering, Tianjin University of Technology and Education, Tianjin 300222 (China)

    2010-08-15T23:59:59.000Z

    We have analyzed ultrafast laser ablation of a metallic target (Nickel) in high vacuum addressing both expansion dynamics of the various plume components (ionic and nanoparticle) and basic properties of the ultrafast laser ablation process. While the ion temporal profile and ion angular distribution were analyzed by means of Langmuir ion probe technique, the angular distribution of the nanoparticulate component was characterized by measuring the thickness map of deposition on a transparent substrate. The amount of ablated material per pulse was found by applying scanning white light interferometry to craters produced on a stationary target. We have also compared the angular distribution of both the ionic and nanoparticle components with the Anisimov model. While the agreement for the ion angular distribution is very good at any laser fluence (from ablation threshold up to {approx_equal}1 J/cm{sup 2}), some discrepancies of nanoparticle plume angular distribution at fluencies above {approx_equal}0.4 J/cm{sup 2} are interpreted in terms of the influence of the pressure exerted by the nascent atomic plasma plume on the initial hydrodynamic evolution of the nanoparticle component. Finally, analyses of the fluence threshold and maximum ablation depth were also carried out, and compared to predictions of theoretical models. Our results indicate that the absorbed energy is spread over a length comparable with the electron diffusion depth L{sub c} ({approx_equal}30 nm) of Ni on the timescale of electron-phonon equilibration and that a logarithmic dependence is well-suited for the description of the variation in the ablation depth on laser fluence in the investigated range.

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

    E-Print Network [OSTI]

    Wheeler, Damon Andreas

    2013-01-01T23:59:59.000Z

    and Photoelectrochemical Properties of Hydrogen-treated TiO2Photoelectrochemical Properties of Hydrogen-Treated TiO 2and ultrafast properties of hydrogen-treated TiO 2 ( H:TiO

  17. Coherent lattice and molecular dynamics in ultrafast single-shot spectroscopy

    E-Print Network [OSTI]

    Poulin, Peter Roland, 1973-

    2005-01-01T23:59:59.000Z

    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 ...

  18. Ultrafast Magnetic Light

    E-Print Network [OSTI]

    Makarov, Sergey V; Krasnok, Alexander E; Belov, Pavel A

    2015-01-01T23:59:59.000Z

    We propose a novel concept for efficient dynamic tuning of optical properties of a high refractive index subwavelength nanoparticle with a magnetic Mie-type resonance by means of femtosecond laser radiation. This concept is based on ultrafast generation of electron-hole plasma within such nanoparticle, drastically changing its transient dielectric permittivity. This allows to manipulate by both electric and magnetic nanoparticle responses, resulting in dramatic changes of its extinction cross section and scattering diagram. Specifically, we demonstrate the effect of ultrafast switching-on a Huygens source in the vicinity of the magnetic dipole resonance. This approach enables to design ultrafast and compact optical switchers and modulators based on the "ultrafast magnetic light" concept.

  19. Direct observation of ultrafast many-body electron dynamics in a strongly-correlated ultracold Rydberg gas

    E-Print Network [OSTI]

    Nobuyuki Takei; Christian Sommer; Claudiu Genes; Guido Pupillo; Haruka Goto; Kuniaki Koyasu; Hisashi Chiba; Matthias Weidemüller; Kenji Ohmori

    2015-04-14T23:59:59.000Z

    Many-body interactions govern a variety of important quantum phenomena ranging from superconductivity and magnetism in condensed matter to solvent effects in chemistry. Understanding those interactions beyond mean field is a holy grail of modern sciences. AMO physics with advanced laser technologies has recently emerged as a new platform to study quantum many-body systems. One of its latest developments is the study of long-range interactions among ultracold particles to reveal the effects of many-body correlations. Rydberg atoms distinguish themselves by their large dipole moments and tunability of dipolar interactions. Most of ultracold Rydberg experiments have been performed with narrow-band lasers in the Rydberg blockade regime. Here we demonstrate an ultracold Rydberg gas in a complementary regime, where electronic coherence is created using a broadband picosecond laser pulse, thus circumventing the Rydberg blockade to induce strong many-body correlations. The effects of long-range Rydberg interactions have been investigated by time-domain Ramsey interferometry with attosecond precision. This approach allows for the real-time observation of coherent and ultrafast many-body dynamics in which the electronic coherence is modulated by the interaction-induced correlations. The modulation evolves more rapidly than expected for two-body correlations by several orders of magnitude. We have actively controlled such ultrafast many-body dynamics by tuning the principal quantum number and the population of the Rydberg state. The observed Ramsey interferograms are well reproduced by a theoretical model beyond mean-field approximation, which can be relevant to other similar many-body phenomena in condensed matter physics and chemistry. Our new approach opens a new avenue to observe and manipulate nonequilibrium dynamics of strongly-correlated quantum many-body systems on the ultrafast timescale.

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

    E-Print Network [OSTI]

    Boxer, Steven G.

    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

  1. 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]

    van Stokkum, Ivo

    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

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

    E-Print Network [OSTI]

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

    2015-01-01T23:59:59.000Z

    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 ...

  3. Ultrafast transmission electron microscopy on dynamic process of a CDW transition in 1T-TaSe2

    E-Print Network [OSTI]

    Sun, Shuaishuai; Li, Zhongwen; Cao, Gaolong; Liu, Y; Lu, W J; Sun, Y P; Tian, Huanfang; HuaixinYang,; Li, Jianqi

    2015-01-01T23:59:59.000Z

    Four-dimensional ultrafast transmission electron microscopy (4D-UTEM) measurements reveal a rich variety of structural dynamic phenomena at a phase transition in the charge-density-wave (CDW) 1T-TaSe2. Through the photoexcitation, remarkable changes on both the CDW intensity and orientation are clearly observed associated with the transformation from a commensurate (C) into an incommensurate (IC) phase in a time-scale of about 3 ps. Moreover, the transient states show up a notable "structurally isosbestic point" at a wave vector of qiso where the C and IC phases yield their diffracting efficiencies in an equally ratio. This fact demonstrates that the crystal planes parallel to qiso adopts visibly common structural features in these two CDW phases. The second-order characters observed in this nonequilibrium phase transition have been also analyzed based on the time-resolved structural data.

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

    SciTech Connect (OSTI)

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

    2012-07-25T23:59:59.000Z

    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.

  5. Hydrogen bonding and solvation dynamics of n-methylacetamide in denatured water (D?O) or denatured chloroform (CDCl?) from nonlinear spectroscopy

    E-Print Network [OSTI]

    McCracken, Justine M. (Justine Meghan), 1979-

    2004-01-01T23:59:59.000Z

    Hydrogen bonding between N-methylacetamide (NMA) and different solvents (D?O or CDCl?) was studied by using two-dimensional infrared spectroscopy to probe the frequency fluctuations of the amide I mode of the solvated NMA. ...

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

    SciTech Connect (OSTI)

    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

    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.

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

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

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

    2015-04-02T23:59:59.000Z

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

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

    E-Print Network [OSTI]

    Hosler, Erik Robert

    2013-01-01T23:59:59.000Z

    dynamics. Tunnel ionization rate determinations are employed to model the pump, while electronic structure calculations

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

    E-Print Network [OSTI]

    Westhof, Eric

    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

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

    E-Print Network [OSTI]

    Feng, Jun

    2010-01-01T23:59:59.000Z

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

  11. High Resolution, Ultrafast SFG Vibrational Spectroscopy | EMSL

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

    240 nm-2600 nm for possible double resonance SFG measurement. The tunable femtosecond pulses from 240 nm to 15000 nm wavelength range also enable ultrafast pump-probe dynamics...

  12. Ultrafast probing of the x-ray-induced lattice and electron dynamics in graphite at atomic-resolution

    SciTech Connect (OSTI)

    Hau-Riege, S

    2010-10-07T23:59:59.000Z

    We used LCLS pulses to excite thin-film and bulk graphite with various different microstructures, and probed the ultrafast ion and electron dynamics through Bragg and x-ray Thomson scattering (XRTS). We pioneered XRTS at LCLS, making this technique viable for other users. We demonstrated for the first time that the LCLS can be used to characterize warm-dense-matter through Bragg and x-ray Thomson scattering. The warm-dense-matter conditions were created using the LCLS beam. Representative examples of the results are shown in the Figure above. In our experiment, we utilized simultaneously both Bragg and two Thomson spectrometers. The Bragg measurements as a function of x-ray fluence and pulse length allows us to characterize the onset of atomic motion at 2 keV with the highest resolution to date. The Bragg detector was positioned in back-reflection, providing us access to scattering data with large scattering vectors (nearly 4{pi}/{lambda}). We found a clear difference between the atomic dynamics for 70 and 300 fs pulses, and we are currently in the process of comparing these results to our models. The outcome of this comparison will have important consequences for ultrafast diffractive imaging, for which it is still not clear if atomic resolution can truly be achieved. The backward x-ray Thomson scattering data suggests that the average graphite temperature and ionization was 10 eV and 1.0, respectively, which agrees with our models. In the forward scattering data, we observed an inelastic feature in the Thomson spectrum that our models currently do not reproduce, so there is food for thought. We are in the process of writing these results up. Depending on if we can combine the Bragg and Thomson data or not, we plan to publish them in a single paper (e.g. Nature or Science) or as two separate papers (e.g. two Phys. Rev. Lett.). We will present the first analysis of the results at the APS Plasma Meeting in November 2010. We had a fantastic experience performing our experiment at the LCLS, and we are grateful to the beamline scientists and all the support personnel for enabling this experiment. A major hurdle was the very short transition time of two days, which despite all our preparations did not give us sufficient time to test the full system before the start of the beam time. We further were not able to make optimal use of the beam time since we had to exchange samples in the middle of the 36-hours shift. An additional 12-hours break could have avoided this. Finally, our experiment would have benefitted from the best possible focus, but 5 shifts do not allow performing the experiment while fine-tuning the focusing optics.

  13. Role of size and defects in ultrafast broadband emission dynamics of ZnO nanostructures

    SciTech Connect (OSTI)

    Appavoo, Kannatassen; Liu, Mingzhao; Sfeir, Matthew Y., E-mail: msfeir@bnl.gov [Center for Functional Nanomaterials, Brookhaven National Laboratory, Upton, New York 11973 (United States)

    2014-03-31T23:59:59.000Z

    As wide bandgap materials are nanostructured for optoelectronics and energy technologies, understanding how size and defects modify the carrier dynamics becomes critical. Here, we examine broadband ultraviolet-visible subpicosecond emission dynamics of prototypical ZnO in bulk, nanowire and nanosphere geometries. Using a high-sensitivity transient emission Kerr-based spectrometer, we probe exciton dynamics in the low fluence regime to determine how defects states impact thermalization and recombination rates. In contrast to steady-state measurements, we transiently identify low-energy emission features that originate from localized excitonic states rather than mid-gap states, characterized by distinct recombination kinetics, and correlate to longer thermalization times. These states are critical for understanding the overall excited state lifetime of materials in this size regime, where crystallinity rather than dimensionality plays a primary role in dictating recombination dynamics.

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

    E-Print Network [OSTI]

    Ramasesha, Krupa

    2013-01-01T23:59:59.000Z

    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 ...

  15. Models for solvated biomolecular structures

    E-Print Network [OSTI]

    Cerutti, David

    2007-01-01T23:59:59.000Z

    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 (

  16. Tracing ultrafast dynamics of strong fields at plasma-vacuum interfaces with longitudinal proton probing

    SciTech Connect (OSTI)

    Abicht, F.; Braenzel, J.; Koschitzki, Ch.; Schnürer, M., E-mail: schnuerer@mbi-berlin.de [Max-Born-Institut, Max-Born-Str. 2a, 12489 Berlin (Germany); Priebe, G. [XFEL GmbH, Notkestr. 85, 22607 Hamburg (Germany); Andreev, A. A. [Max-Born-Institut, Max-Born-Str. 2a, 12489 Berlin (Germany); Vavilov State Optical Institut, Birzhevaya line 12, 199064 St. Petersburg (Russian Federation); St. Petersburg University, 199064 St. Petersburg, University emb.6 (Russian Federation); Nickles, P. V. [Max-Born-Institut, Max-Born-Str. 2a, 12489 Berlin (Germany); Center of Relativistic Laser Science, Institute for Basic Science, Gwangju 500-712 (Korea, Republic of); Sandner, W. [Max-Born-Institut, Max-Born-Str. 2a, 12489 Berlin (Germany); Technical University Berlin, Straße des 17. Juni 135, 10623 Berlin (Germany); ELI-DC International Association AISBL, c/o DESY – StandortZeuthen, Platanenallee 6, 15738 Zeuthen (Germany)

    2014-07-21T23:59:59.000Z

    If regions of localized strong fields at plasma-vacuum interfaces are probed longitudinally with laser accelerated proton beams their velocity distribution changes sensitively and very fast. Its measured variations provide indirectly a higher temporal resolution as deduced from deflection geometries which rely on the explicit temporal resolution of the proton beam at the position of the object to probe. With help of reasonable models and comparative measurements changes of proton velocity can trace the field dynamics even at femtosecond time scale. In longitudinal probing, the very low longitudinal emittance together with a broad band kinetic energy distribution of laser accelerated protons is the essential prerequisite of the method. With a combination of energy and one-dimensional spatial resolution, we resolve fast field changes down to 100 fs. The used pump probe setup extends previous schemes and allows discriminating simultaneously between electric and magnetic fields in their temporal evolution.

  17. Ultrafast dynamics and fragmentation of C60 in intense laser pulses

    E-Print Network [OSTI]

    Lin, Zheng-Zhe

    2014-01-01T23:59:59.000Z

    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.

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

    SciTech Connect (OSTI)

    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

    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.

  19. Ultrafast scanning tunneling microscopy

    SciTech Connect (OSTI)

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

    1995-09-01T23:59:59.000Z

    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.

  20. Preparation of cerium halide solvate complexes

    DOE Patents [OSTI]

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

    2013-08-06T23:59:59.000Z

    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.

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

    SciTech Connect (OSTI)

    Glinka, Yuri D., 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

    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.

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

    SciTech Connect (OSTI)

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

    2014-05-21T23:59:59.000Z

    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.

  3. Ultrafast nonlinear optical properties of passive and active semiconductor devices

    E-Print Network [OSTI]

    Motamedi, Ali Reza

    2011-01-01T23:59:59.000Z

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

  4. Ultrafast studies of photodissociation in solution: Dissociation, recombination and relaxation

    SciTech Connect (OSTI)

    King, J.C.

    1995-05-01T23:59:59.000Z

    Photodissociation of M(CO){sub 6} (M=Cr,Mo,W) and the formation of solvated M(CO){sub 5}{center_dot}S complex was studied in cyclohexane; rate-limiting step is vibrational energy relaxation from the new bond to the solvent. For both M=Cr and Mo, the primary relaxation occurs in 18 ps; for Cr, there is an additional vibrational relaxation (150 ps time scale) of a CO group poorly coupled to other modes. Relaxation of M=W occurs in 42 ps; several possible mechanisms for the longer cooling are discussed. Vibrational relaxation is also investigated for I{sub 2}{sup -} and IBr{sup {minus}} in nonpolar and slightly polar solvents. Attempts were made to discover the mechanism for the fast energy transfer in nonpolar solvent. The longer time scale dynamics of I{sub 3}{sup {minus}} and IBr{sub 2}{sup {minus}} were also studied; both formed a metastable complex following photodissociation and 90-95% return to ground state in 100 ps, implying a barrier to recombination of 4.3 kcal/mol and a barrier to escape of {ge}5.5 kcal/mol. The more complex photochemistry of M{sub 3}(CO){sub 12} (M=Fe,Ru) is also investigated, using visible and ultraviolet radiations, dissociation, geminate recombination, vibrational relaxation, and bridging structures and their reactions were studied. Attempts were made to extend ultrafast spectroscopy into the mid-infrared, but signal-to-noise was poor.

  5. 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...

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

    E-Print Network [OSTI]

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

    2015-01-01T23:59:59.000Z

    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...

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

    SciTech Connect (OSTI)

    Gadd, S.E.

    1995-08-01T23:59:59.000Z

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

  8. Ion Solvation Thermodynamics from Simulation with a Polarizable Force Field

    E-Print Network [OSTI]

    Ponder, Jay

    solvation free energies into distinct cation and anion contributions without reference to an additional solvation free energies for potassium, sodium, and chloride ions in liquid water and formamide-cluster solvation enthalpies, and experimental solvation free energies for whole salts, while the other force fields

  9. Supporting Information for: Single-Ion Solvation Free Energies and the

    E-Print Network [OSTI]

    Truhlar, Donald G

    1 Supporting Information for: Single-Ion Solvation Free Energies and the Normal Hydrogen Electrode Absolute Solvation Free Energies......................................................... 3 Conventional Solvation Free Energies....................................................4 Standard Reduction Potentials

  10. Solvation in the Cramer-Truhlar Developing solvation models that permit the

    E-Print Network [OSTI]

    Truhlar, Donald G

    Comput. 2005, 1, 1133 Change in the solute free energy due to electrostatic interactions between is modeled as a dielectric continuum. SM6 calculates aqueous solvation free energies based on gas or liquid-bulk electrostatic contributions to the free energy of hydration: first solvation shell effects The GCDS term

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

    E-Print Network [OSTI]

    Collum, David B.

    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

  12. Influence of solvation on the structural and capacitive properties of electrical double layer capacitors

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    . The electrolytes, represented by coarse-grained models, are enclosed between graphite electrodes. We employ capacitance, solvation, molecular dynamics simulations, interfacial structure, graphite 2 hal-00853396,version batteries. They can be used as high-power generators and can undergo one million charge/discharge cycles

  13. Ultrafast Spectroscopy of Correlated Electron Systems

    E-Print Network [OSTI]

    Schmid, Benjamin Andrew

    2009-01-01T23:59:59.000Z

    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

  14. Quantum Chemistry for Solvated Molecules on Graphical Processing Units (GPUs)using Polarizable Continuum Models

    E-Print Network [OSTI]

    Liu, Fang; Kulik, Heather J; Martínez, Todd J

    2015-01-01T23:59:59.000Z

    The conductor-like polarization model (C-PCM) with switching/Gaussian smooth discretization is a widely used implicit solvation model in chemical simulations. However, its application in quantum mechanical calculations of large-scale biomolecular systems can be limited by computational expense of both the gas phase electronic structure and the solvation interaction. We have previously used graphical processing units (GPUs) to accelerate the first of these steps. Here, we extend the use of GPUs to accelerate electronic structure calculations including C-PCM solvation. Implementation on the GPU leads to significant acceleration of the generation of the required integrals for C-PCM. We further propose two strategies to improve the solution of the required linear equations: a dynamic convergence threshold and a randomized block-Jacobi preconditioner. These strategies are not specific to GPUs and are expected to be beneficial for both CPU and GPU implementations. We benchmark the performance of the new implementat...

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

    SciTech Connect (OSTI)

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

    2014-09-21T23:59:59.000Z

    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.

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

    SciTech Connect (OSTI)

    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

    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.

  17. Solvated electron lithium electrode for high energy density battery

    SciTech Connect (OSTI)

    Sammels, A.F.

    1987-08-04T23:59:59.000Z

    A solvated electron lithium negative electrode is described containing: containment means holding a solution of lithium dissolved in liquid ammonia to form a solvated electron solution, the solvated electron solution contacting a lithium intercalating membrane and providing lithium to the intercalating membrane during discharge and accepting it from the intercalating membrane during charge.

  18. Plasmonic enhanced ultrafast switch.

    SciTech Connect (OSTI)

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

    2009-09-01T23:59:59.000Z

    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.

  19. Ptychographic ultrafast pulse reconstruction

    E-Print Network [OSTI]

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

    2014-01-01T23:59:59.000Z

    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.

  20. 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)

    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

    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.

  1. Direct Observation of Optically Induced Transient Structures in Graphite Using Ultrafast Electron Crystallography

    E-Print Network [OSTI]

    initio density functional calculations, we trace the governing mechanism back to electronic structure changes in the electronic properties, direct de- termination of lattice structural dynamics from opticalDirect Observation of Optically Induced Transient Structures in Graphite Using Ultrafast Electron

  2. Ultrafast optical spin echo for electron spins in semiconductors

    E-Print Network [OSTI]

    Susan M. Clark; Kai-Mei C. Fu; Qiang Zhang; Thaddeus D. Ladd; Colin Stanley; Yoshihisa Yamamoto

    2009-04-03T23:59:59.000Z

    Spin-based quantum computing and magnetic resonance techniques rely on the ability to measure the coherence time, T2, of a spin system. We report on the experimental implementation of all-optical spin echo to determine the T2 time of a semiconductor electron-spin system. We use three ultrafast optical pulses to rotate spins an arbitrary angle and measure an echo signal as the time between pulses is lengthened. Unlike previous spin-echo techniques using microwaves, ultrafast optical pulses allow clean T2 measurements of systems with dephasing times T2* fast in comparison to the timescale for microwave control. This demonstration provides a step toward ultrafast optical dynamic decoupling of spin-based qubits.

  3. Femtosecond laser studies of ultrafast intramolecular processes

    SciTech Connect (OSTI)

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

    1993-12-01T23:59:59.000Z

    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.

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

    E-Print Network [OSTI]

    Gu, Chenji

    2012-01-01T23:59:59.000Z

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

  5. 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: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level:Energy: Grid Integration Redefining What'sis Taking Over OurThe Iron Spin TransitionProgram |FrankUltrafast Spectroscopy ofUltrafastUltrafast

  6. 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: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level:Energy: Grid Integration Redefining What'sis Taking Over OurThe Iron Spin TransitionProgram |FrankUltrafast SpectroscopyUltrafastUltrafast

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

    E-Print Network [OSTI]

    Broomberg, Steven E.

    2010-01-01T23:59:59.000Z

    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

  8. Linking Ion Solvation and Lithium Battery Electrolyte Properties...

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

    Battery Electrolyte Properties Linking Ion Solvation and Lithium Battery Electrolyte Properties 2010 DOE Vehicle Technologies and Hydrogen Programs Annual Merit Review and...

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

    E-Print Network [OSTI]

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

    2015-03-25T23:59:59.000Z

    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.

  10. A QM/MM Study on the Aqueous Solvation of theTetrahydroxouranylate...

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

    transfer of the tetrahydroxouranylate to the solvating water molecules is relatively modest, and can be modeled by including a solvation layer consisting of 12 explicit water...

  11. Ultrafast optics For optics and photonics course,

    E-Print Network [OSTI]

    Palffy-Muhoray, Peter

    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

  12. High-Pulse-Energy Ultrafast Laser for

    E-Print Network [OSTI]

    Painter, Kevin

    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

  13. Lithium Hexamethyldisilazide: A View of Lithium Ion Solvation

    E-Print Network [OSTI]

    Collum, David B.

    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

  14. Lithium Diisopropylamide Solvated by Hexamethylphosphoramide: Substrate-Dependent

    E-Print Network [OSTI]

    Collum, David B.

    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

  15. Classical density functional theory to tackle solvation in molecular liquids

    E-Print Network [OSTI]

    Jeanmairet, Guillaume; Sergiievskyi, Volodymyr; Borgis, Daniel

    2015-01-01T23:59:59.000Z

    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.

  16. Photoelectron spectroscopy of solvated electrons in alcohol and acetonitrile microjets

    E-Print Network [OSTI]

    Neumark, Daniel M.

    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

  17. Unraveling shock-induced chemistry using ultrafast lasers

    SciTech Connect (OSTI)

    Moore, David Steven [Los Alamos National Laboratory

    2010-12-06T23:59:59.000Z

    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.

  18. Unraveling shock-induced chemistry using ultrafast lasers

    SciTech Connect (OSTI)

    Moore, David S [Los Alamos National Laboratory

    2009-01-01T23:59:59.000Z

    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 of fast 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 micro-engineered interfaces in tunable energetic mixtures.

  19. Rabi oscillations of Morris-Shore transformed $N$-state systems by elliptically polarized ultrafast laser pulses

    E-Print Network [OSTI]

    Kim, Hyosub; Lee, Han-gyeol; Ahn, Jaewook

    2015-01-01T23:59:59.000Z

    We present an experimental investigation of ultrafast-laser driven Rabi oscillations of atomic rubidium. Since the broadband spectrum of an ultrafast laser pulse simultaneously couples all the electronic hyperfine transitions between the excited and ground states, the complex excitation linkages involved with the D1 or D2 transition are energy degenerate. Here, by applying the Morris-Shore transformation, it is shown that this multi-state system is reduced to a set of independent two-state systems and dark states. In experiments performed by ultrafast laser interactions of atomic rubidium in the strong interaction regime, we demonstrate that the ultrafast dynamics of the considered multi-state system is governed by a sum of at most two decoupled Rabi oscillations when this system interacts with ultrafast laser pulses of any polarization state. We further show the implication of this result to possible controls of photo-electron polarizations.

  20. Cells containing solvated electron lithium negative electrodes

    SciTech Connect (OSTI)

    Uribe, F.A.; Semkow, K.W.; Sammells, A.F. (Eltron Research, Incorporated, Aurora, IL (US))

    1989-12-01T23:59:59.000Z

    Preliminary work performed on a novel solvated electron lithium negative electrode which may have application in either high energy density secondary or reserve battery systems is discussed. The lithium electrode investigated consisted of lithium initially dissolved in liquid ammonia to give a solvated electron solution. Containment of this liquid negative active material from direct contact with a liquid nonaqueous electrolyte present in the cell positive electrode compartment was addressed via the use of a lithium intercalated electronically conducting ceramic membrane of the general composition Li{sub x}WO{sub 2}(0.1{lt}x{lt} 1.0). Secondary electrochemical cells having the general configuration Li,NH{sub 3}/Li{sub x}WO{sub 2}NAE/TiS{sub 2} using nonaqueous electrolytes (NAE) based upon both propylene carbonate and 2Me-THF. Depending upon initial lithium activity in the negative electrode compartments the cell possessed an initial open-circuit potential (OCP 3.44V). Both cells, which were operated at ambient pressure (low temperature) and ambient temperature (high pressure) showed evidence for electrochemical reversibility.

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

    E-Print Network [OSTI]

    Truong, Thanh N.

    A coupled RISM/MD or MC simulation methodology for solvation free energies Holly Freedman, Thanh N methods for determination of solvation free energies. We employ the RISM formulation of solvation free-netted chain equations. We apply this approach to determining free energies of solvation for several small

  2. Ultrafast scanning probe microscopy

    DOE Patents [OSTI]

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

    1995-01-01T23:59:59.000Z

    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.

  3. Ultrafast scanning probe microscopy

    DOE Patents [OSTI]

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

    1995-05-16T23:59:59.000Z

    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.

  4. Ultrafast gas switching experiments

    SciTech Connect (OSTI)

    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

    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.

  5. Spectral Noise Correlations of an Ultrafast Frequency Comb

    E-Print Network [OSTI]

    Roman Schmeissner; Jonathan Roslund; Claude Fabre; Nicolas Treps

    2014-10-16T23:59:59.000Z

    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.

  6. 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: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level:Energy: Grid Integration Redefining What'sis Taking Over OurThe Iron Spin TransitionProgram |FrankUltrafast Spectroscopy ofUltrafast

  7. 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: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level:Energy: Grid Integration Redefining What'sis Taking Over OurThe Iron Spin TransitionProgram |FrankUltrafast SpectroscopyUltrafast

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

    E-Print Network [OSTI]

    Purdue University

    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

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

    E-Print Network [OSTI]

    Peinke, Joachim

    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

  10. Novel Applications of Ultrafast Laser

    E-Print Network [OSTI]

    Dantus, Marcos

    21 Novel Applications of Ultrafast Laser Spectroscopy Professor of chemistry and Adjunct Professor LASER PULSESare considered photonic reagents that can be used to study and control chemistry by our group. We are engaged in developing the laser technology as well as the novel applications that become

  11. 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...

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

    SciTech Connect (OSTI)

    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

    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.

  13. Ultrafast charge localization in a stripe-phase nickelate

    SciTech Connect (OSTI)

    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

    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.

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

    E-Print Network [OSTI]

    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

    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...

  15. Femtosecond pulse imaging: ultrafast optical oscilloscope

    E-Print Network [OSTI]

    Fainman, Yeshaiahu

    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

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

    E-Print Network [OSTI]

    Li, Teng

    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

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

    E-Print Network [OSTI]

    Aeschlimann, Martin

    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

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

    E-Print Network [OSTI]

    Hagen, Stephen J.

    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

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

    E-Print Network [OSTI]

    Fayer, Michael D.

    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

  20. Impact system for ultrafast synchrotron experiments

    SciTech Connect (OSTI)

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

    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.

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

    E-Print Network [OSTI]

    Luhua, Lai

    Estimating 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 free energy and the correct scoring in docking studies. We have developed a new solvation energy

  2. Proton Solvation and Proton Mobility Department of Physical Chemistry and the Fritz Haber Research Center,

    E-Print Network [OSTI]

    Agmon, Noam

    Proton Solvation and Proton Mobility NOAM AGMON Department of Physical Chemistry and the Fritz for proton solvation and proton mobility is analyzed and the results are compared with recent simulations. Three factors con­ tribute to differences in proton solvation energies: hydrogen­bond cleavage, changes

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

    E-Print Network [OSTI]

    Mezei, Mihaly

    Studies on free energy calculations. II. A theoretical approach to molecular solvation Haluk Resat methods of performing the thermodynamic integration in solvation free energy calculations are also at the particle creation limit in obtaining quantitatively reliable results for the solvation free energies. I

  4. Theory of solvation in polar nematics Vitaly Kapko and Dmitry V. Matyushova

    E-Print Network [OSTI]

    Matyushov, Dmitry

    Theory of solvation in polar nematics Vitaly Kapko and Dmitry V. Matyushova Department of Chemistry develop a linear response theory of solvation of ionic and dipolar solutes in anisotropic, axially symmetric polar solvents. The theory is applied to solvation in polar nematic liquid crystals. The formal

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

    SciTech Connect (OSTI)

    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

    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.

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

    SciTech Connect (OSTI)

    Trulove, Paul C; Foley, Matthew P

    2013-03-14T23:59:59.000Z

    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.

  7. Observation of off-Hugoniot shocked states with ultrafast time resolution

    SciTech Connect (OSTI)

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

    2010-02-23T23:59:59.000Z

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

  8. Ultrafast, high precision gated integrator

    SciTech Connect (OSTI)

    Wang, X.

    1995-01-01T23:59:59.000Z

    An ultrafast, high precision gated integrator has been developed by introducing new design approaches that overcome the problems associated with earlier gated integrator circuits. The very high speed is evidenced by the output settling time of less than 50 ns and 20 MHz input pulse rate. The very high precision is demonstrated by the total output offset error of less than 0.2mV and the output droop rate of less than 10{mu}V/{mu}s. This paper describes the theory of this new gated integrator circuit operation. The completed circuit test results are presented.

  9. 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: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level:Energy: Grid Integration Redefining What'sis Taking Over OurThe Iron Spin TransitionProgram |FrankUltrafast Spectroscopy

  10. 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: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645U.S. DOE Office of ScienceandMesa del SolStrengthening aTurbulence may bedieselsummerFact SheetsUltrafastSpectroscopy

  11. Microscopic linear liquid streams in vacuum: Injection of solvated biological samples into X-ray free electron lasers

    SciTech Connect (OSTI)

    Doak, R. B.; DePonte, D. P.; Nelson, G.; Camacho-Alanis, F.; Ros, A.; Spence, J. C. H.; Weierstall, U. [Arizona State University, Tempe, AZ 85287-1504 (United States); Centre for Free-Electron Laser Science, DESY, D-22607 Hamburg (Germany); Arizona State University, Tempe, AZ 85287-1504 (United States)

    2012-11-27T23:59:59.000Z

    Microscopic linear liquid free-streams offer a means of gently delivering biological samples into a probe beam in vacuum while maintaining the sample species in a fully solvated state. By employing gas dynamic forces to form the microscopic liquid stream (as opposed to a conventional solid-walled convergent nozzle), liquid free-streams down to 300 nm diameter have been generated. Such 'Gas Dynamic Virtual Nozzles' (GDVN) are ideally suited to injecting complex biological species into an X-ray Free Electron Laser (XFEL) to determine the structure of the biological species via Serial Femtosecond Crystallography (SFX). GDVN injector technology developed for this purpose is described.

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

    E-Print Network [OSTI]

    Skarmoutsos, Ioannis; Vetere, Valentina; Mossa, Stefano

    2014-01-01T23:59:59.000Z

    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...

  13. The Solvation and Dissociation of 4Benzylaniline Hydrochloride in Chlorobenzene

    E-Print Network [OSTI]

    Miller, Alice

    of solvated 4-benzylaniline from solid 4-benzylaniline hydrochloride is possible under "open" conditions of the decomposition of the hydrochloride salt (the back reaction of eq 3) is appropriate and could lead al. showed the dissolution of hydrogen chloride gas in chlorobenzene required rigorous mixing and

  14. Ultrafast infrared studies of complex ligand rearrangements in solution

    SciTech Connect (OSTI)

    Payne, Christine K.

    2003-05-31T23:59:59.000Z

    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.

  15. 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...

  16. Ultrafast Optical Pulses: Synthesis and Applications

    E-Print Network [OSTI]

    Wang, Kai

    2013-12-11T23:59:59.000Z

    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...

  17. An ultrafast carbon nanotube terahertz polarisation modulator

    SciTech Connect (OSTI)

    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

    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.

  18. Reorientation and Solvation Dynamics of Bulk and Confined Alcohols

    E-Print Network [OSTI]

    Vartia, Anthony Andrew

    2012-12-31T23:59:59.000Z

    . . . . . . . . 10 1.1.2 Jump Model . . . . . . . . . . . . . . . . . . . . . . . . 10 1.1.3 Extended Jump Model . . . . . . . . . . . . . . . . . . . 11 1.2 Experimental Measurements of Reorientation . . . . . . . . . . . 15 1.2.1 Nuclear Magnetic Resonance... . . . . . . . . . . . . . . . 15 1.2.2 Optical Kerr Effect Spectroscopy . . . . . . . . . . . . . 16 1.2.3 Two-dimensional Infrared Spectroscopy . . . . . . . . . . 18 1.2.4 Infrared Pump-probe Anisotropy Measurements . . . . . . 19 1.3 Time-dependent Fluorescence Spectroscopy...

  19. Broadband laser cooling of trapped atoms with ultrafast pulses

    E-Print Network [OSTI]

    Blinov, Boris

    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

  20. Ultrafast x-rays: radiographing magnetism Project overview

    E-Print Network [OSTI]

    Haviland, David

    , 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

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

    SciTech Connect (OSTI)

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

    2014-11-13T23:59:59.000Z

    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.

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

    SciTech Connect (OSTI)

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

    2014-09-30T23:59:59.000Z

    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).

  3. Solvated electron lithium electrode for high energy density battery

    SciTech Connect (OSTI)

    Sammells, A.F.

    1987-05-26T23:59:59.000Z

    A rechargeable high energy density lithium-based cell is described comprising: a solvated electron lithium negative electrode comprising a solution of lithium dissolved in liquid ammonia; a lithium ion conducting solid electrolyte contacting the negative electrode; a liquid non-aqueous lithium ion conducting electrolyte comprising a lithium ion conducting supporting electrolyte dissolved in a non-aqueous solvent. The liquid electrolyte contacting the lithium ion conducting solid electrolyte; and a solid lithium intercalation positive electrode contacting the liquid electrolyte.

  4. Communication: Barium ions and helium nanodroplets: Solvation and desolvation

    SciTech Connect (OSTI)

    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

    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.

  5. Dielectric Boundary Force in Biomolecular Solvation

    E-Print Network [OSTI]

    Li, Bo

    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

  6. Two-Color Ultrafast Photoexcited Scanning Tunneling Microscopy

    SciTech Connect (OSTI)

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

    2011-05-26T23:59:59.000Z

    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.

  7. Atomic Resolution Coherent Diffractive Imaging and Ultrafast Science

    SciTech Connect (OSTI)

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

    2011-01-12T23:59:59.000Z

    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.

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

    SciTech Connect (OSTI)

    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

    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.

  9. 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: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level:Energy: Grid Integration Redefining What'sis Taking Over OurThe Iron Spin TransitionProgram |FrankUltrafast Spectroscopy of WarmUltrafast

  10. Ultra--fast carriers relaxation in bulk silicon following photo--excitation with a short and polarized laser pulse

    E-Print Network [OSTI]

    Sangalli, Davide

    2014-01-01T23:59:59.000Z

    A novel approach based on the merging of the out--of--equilibrium Green's function method with the ab-initio, Density--Functional--Theory is used to describe the ultra--fast carriers relaxation in Silicon. The results are compared with recent two photon photo--emission measurements. We show that the interpretation of the carrier relaxation in terms of L -> X inter--valley scattering is not correct. The ultra--fast dynamics measured experimentally is, instead, due to the scattering between degenerate $L$ states that is activated by the non symmetric population of the conduction bands induced by the laser field. This ultra--fast relaxation is, then, entirely due to the specific experimental setup and it can be interpreted by introducing a novel definition of the quasi--particle lifetimes in an out--of--equilibrium context.

  11. PURDUE UNIVERSITY ULTRAFAST OPTICS AND OPTICAL FIBER COMMUNICATIONS LABORATORY Femtosecond Pulse

    E-Print Network [OSTI]

    Purdue University

    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

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

    E-Print Network [OSTI]

    Keller, Ursula

    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

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

    E-Print Network [OSTI]

    Purdue University

    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

  14. 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

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

    E-Print Network [OSTI]

    Li, Bo

    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

  16. Probing reaction dynamics of transition-metal complexes in solution via time-resolved soft x-ray spectroscopy

    SciTech Connect (OSTI)

    Huse, N.; Kim, T.-K.; Khalil, M.; Jamula, L.; McCusker, J.K.; Schoenlein, R.W.

    2008-08-01T23:59:59.000Z

    We report the first time-resolved soft x-ray measurements of solvated transition-metal complexes. L-edge spectroscopy directly probes dynamic changes in ligand-field splitting of 3d orbitals associated with the spin transition, and mediated by changes in ligand-bonding. We report the first time-resolved soft x-ray spectroscopy of solution-phase molecular dynamics. Changes in ligand-field splitting and spin-state populations in 3d orbitals of the Fe{sup II} complex are directly probed via transient absorption changes of the Fe L{sub 2} and L{sub 3} edges following photo-induced metal-to-ligand charge transfer. With the emergence of high-flux ultrafast soft x-ray sources, details on interplay between atomic structure, electronic states, and spin contributions will be revealed. Our experimental approach opens the door to femtosecond soft x-ray investigations of liquid phase chemistry that have previously been inaccessible.

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

    E-Print Network [OSTI]

    Cotoros, Ingrid A.

    2009-01-01T23:59:59.000Z

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

  18. Attosecond timing the ultrafast charge-transfer process in atomic collisions

    SciTech Connect (OSTI)

    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

    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.

  19. Suppression of Magnetic State Decoherence Using Ultrafast Optical Pulses

    E-Print Network [OSTI]

    C. Search; P. R. Berman

    2000-03-01T23:59:59.000Z

    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.

  20. Ultrafast charge localization in a stripe-phase nickelate

    E-Print Network [OSTI]

    Coslovich, Giacomo

    2013-01-01T23:59:59.000Z

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

  1. Advanced Imaging and Ultra-fast Material Probing With Inverse...

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

    Imaging and Ultra-fast Material Probing With Inverse Compton Scattering A proposal to the Brookhaven Accelerator Test Facility Gerard Andonian, Alberto Bacci, Ubaldo...

  2. Ultrafast Pulse Shaping Approaches to Quantum Computing

    E-Print Network [OSTI]

    Debabrata Goswami

    2003-12-24T23:59:59.000Z

    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.

  3. Laser cooling with ultrafast pulse trains

    E-Print Network [OSTI]

    David Kielpinski

    2003-06-14T23:59:59.000Z

    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.

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

    E-Print Network [OSTI]

    Wechsler, Risa H.

    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

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

    E-Print Network [OSTI]

    Monroe, Christopher

    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

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

    E-Print Network [OSTI]

    Cao, Jianshu

    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

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

    E-Print Network [OSTI]

    Cao, Jianshu

    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

  8. Layering Transitions and Solvation Forces in an Asymmetrically Confined Fluid

    E-Print Network [OSTI]

    Maria C. Stewart; Robert Evans

    2014-08-29T23:59:59.000Z

    We consider a simple fluid confined between two parallel walls (substrates), separated by a distance L. The walls exert competing surface fields so that one wall is attractive and may be completely wet by liquid (it is solvophilic) while the other is solvophobic. Such asymmetric confinement is sometimes termed a `Janus Interface'. The second wall is: (i) purely repulsive and therefore completely dry (contact angle 180 degrees) or (ii) weakly attractive and partially dry (the contact angle is typically in the range 160-170 degrees). At low temperatures, but above the bulk triple point, we find using classical density functional theory (DFT) that the fluid is highly structured in the liquid part of the density profile. In case (i) a sequence of layering transitions occurs: as L is increased at fixed chemical potential (mu) close to bulk gas--liquid coexistence, new layers of liquid-like density develop discontinuously. In contrast to confinement between identical walls, the solvation force is repulsive for all wall separations and jumps discontinuously at each layering transition and the excess grand potential exhibits many metastable minima as a function of the adsorption. For a fixed temperature T=0.56Tc, where Tc is the bulk critical temperature, we determine the transition lines in the L, mu plane. In case (ii) we do not find layering transitions and the solvation force oscillates about zero. We discuss how our mean-field DFT results might be altered by including effects of fluctuations and comment on how the phenomenology we have revealed might be relevant for experimental and simulation studies of water confined between hydrophilic and hydrophobic substrates, emphasizing it is important to distinguish between cases (i) and (ii).

  9. Solvation Free Energies of Alanine Peptides: The Effect of Flexibility

    SciTech Connect (OSTI)

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

    2013-12-03T23:59:59.000Z

    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.

  10. DIRECT SPACE-TO-TIME PULSE SHAPING FOR ULTRAFAST OPTICAL

    E-Print Network [OSTI]

    Purdue University

    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

  11. 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

  12. Information processing with longitudinal spectral decomposition of ultrafast pulses

    E-Print Network [OSTI]

    Fainman, Yeshaiahu

    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

  13. Solvation of positive ions in water: The dominant role of water-water interaction

    E-Print Network [OSTI]

    Christian Krekeler; Luigi Delle Site

    2007-02-09T23:59:59.000Z

    Local polarization effects, induced by mono and divalent positive ions in water, influence (and in turn are influenced by) the large scale structural properties of the solvent. Experiments can only distinguish this process of interplay in a generic qualitative way. Instead, first principles quantum calculations can address the question at both electronic and atomistic scale, accounting for electronic polarization as well as geometrical conformations. For this reason we study the extension of the scales' interconnection by means of first principle Car-Parrinello molecular dynamics applied to systems of different size. In this way we identify the general aspects dominating the physics of the first solvation shell and their connection to the effects related to the formation of the outer shells and eventually the bulk. We show that while the influence of the ions is extended to the first shell only, the water-water interaction is instead playing a dominant role even within the first shell independently from the size or the charge of the ion.

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

    E-Print Network [OSTI]

    Davidson, Robert

    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 ...

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

    E-Print Network [OSTI]

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

    2014-06-11T23:59:59.000Z

    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.

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

    E-Print Network [OSTI]

    Wolfson, Johanna Wendlandt

    2013-01-01T23:59:59.000Z

    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 ...

  17. 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: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level:Energy: Grid Integration Redefining What'sis Taking Over OurThe Iron Spin TransitionProgram |Frank CasellaEnergyUltracoldConnectUltrafast

  18. 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: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level:Energy: Grid Integration Redefining What'sis Taking Over OurThe Iron Spin TransitionProgram |FrankUltrafast Spectroscopy of Warm Dense Matter

  19. 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: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level:Energy: Grid Integration Redefining What'sis Taking Over OurThe Iron Spin TransitionProgram |FrankUltrafast Spectroscopy of Warm Dense

  20. 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: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level:Energy: Grid Integration Redefining What'sis Taking Over OurThe Iron Spin TransitionProgram |FrankUltrafast Spectroscopy of Warm

  1. 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: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645U.S. DOE Office of ScienceandMesa del SolStrengthening aTurbulence may bedieselsummerFact SheetsUltrafastSpectroscopy of

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

    E-Print Network [OSTI]

    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

    , respectively). 48 Thus, in terms of carrier dynamics, DWNTs are comparable to SWNTs. Further, DWNTs can have outer and inner wall combinations with different electronic types (semi- conducting, s, or metallic, m) in their structures (outer-inner: s-s, s-m, m... .; Hennrich, F.; White, I. H.; Milne, W. I.; Ferrari, A. C. Carbon Nanotube-Polycarbonate Composites for Ultrafast La- sers. Adv. Mater. 2008, 20, 4040–4043. 21. Wang, F.; Rozhin, A. G.; Scardaci, V.; Sun, Z.; Hennrich, F.; White, I. H.; Milne, W. I.; Ferrari...

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

    E-Print Network [OSTI]

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

    2015-01-01T23:59:59.000Z

    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.

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

    SciTech Connect (OSTI)

    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

    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.

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

    E-Print Network [OSTI]

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

    2006-01-01T23:59:59.000Z

    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

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

    E-Print Network [OSTI]

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

    2003-01-01T23:59:59.000Z

    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

  7. 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]

    Kamerlin, Shina C. L.

    2009-01-01T23:59:59.000Z

    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

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

    SciTech Connect (OSTI)

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

    2013-08-28T23:59:59.000Z

    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.

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

    E-Print Network [OSTI]

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

    2002-01-01T23:59:59.000Z

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

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

    SciTech Connect (OSTI)

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

    2014-04-17T23:59:59.000Z

    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.

  11. Controlling ultrafast currents by the non-linear photogalvanic effect

    E-Print Network [OSTI]

    Wachter, Georg; Lemell, Christoph; Tong, Xiao-Min; Yabana, Kazuhiro; Burgdörfer, Joachim

    2015-01-01T23:59:59.000Z

    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.

  12. Space charge effects in ultrafast electron diffraction and imaging

    SciTech Connect (OSTI)

    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

    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.

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

    DOE Patents [OSTI]

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

    1999-08-10T23:59:59.000Z

    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.

  14. High-performance laser processing using manipulated ultrafast laser pulses

    SciTech Connect (OSTI)

    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

    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.

  15. Controlling ultrafast currents by the non-linear photogalvanic effect

    E-Print Network [OSTI]

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

    2015-03-20T23:59:59.000Z

    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.

  16. Ultrafast pump-probe force microscopy with nanoscale resolution

    E-Print Network [OSTI]

    2015-01-01T23:59:59.000Z

    Cerullo, “Confocal ultrafast pump-probe spectroscopy: A newand H. J. Maris, “Time-resolved pump-probe experiments withand U. Keller, “Femtosecond pump-porbe near-field optical

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

    E-Print Network [OSTI]

    Jayaram, Bhyravabotla

    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

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

    E-Print Network [OSTI]

    Meirovitch, Hagai

    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

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

    E-Print Network [OSTI]

    Chaban, Vitaly

    2015-01-01T23:59:59.000Z

    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).

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

    E-Print Network [OSTI]

    Chaban, Vitaly

    2014-01-01T23:59:59.000Z

    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.

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

    SciTech Connect (OSTI)

    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

    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.

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

    E-Print Network [OSTI]

    Nguyen, Dat H.

    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

  3. 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...

  4. 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...

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

    E-Print Network [OSTI]

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

    2009-01-01T23:59:59.000Z

    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 ...

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

    E-Print Network [OSTI]

    Purdue University

    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

  7. Ultrafast studies of organometallic photochemistry: The mechanism of carbon-hydrogen bond activation in solution

    SciTech Connect (OSTI)

    Bromberg, S.E.

    1998-05-01T23:59:59.000Z

    When certain organometallic compounds are photoexcited in room temperature alkane solution, they are able to break or activate the C-H bonds of the solvent. Understanding this potentially practical reaction requires a detailed knowledge of the entire reaction mechanism. Because of the dynamic nature of chemical reactions, time-resolved spectroscopy is commonly employed to follow the important events that take place as reactants are converted to products. For the organometallic reactions examined here, the electronic/structural characteristics of the chemical systems along with the time scales for the key steps in the reaction make ultrafast UV/Vis and IR spectroscopy along with nanosecond Step-Scan FTIR spectroscopy the ideal techniques to use for this study. An initial study of the photophysics of (non-activating) model metal carbonyls centering on the photodissociation of M(CO){sub 6} (M = Cr, W, Mo) was carried out in alkane solutions using ultrafast IR spectroscopy. Next, picosecond UV/vis studies of the C-H bond activation reaction of Cp{sup *}M(CO){sub 2} (M = Rh, Ir), conducted in room temperature alkane solution, are described in an effort to investigate the origin of the low quantum yield for bond cleavage ({approximately}1%). To monitor the chemistry that takes place in the reaction after CO is lost, a system with higher quantum yield is required. The reaction of Tp{sup *}Rh(CO){sub 2} (Tp{sup *} = HB-Pz{sub 3}{sup *}, Pz{sup *} = 3,5-dimethylpyrazolyl) in alkanes has a quantum yield of {approximately}30%, making time resolved spectroscopic measurements possible. From ultrafast IR experiments, two subsequently formed intermediates were observed. The nature of these intermediates are discussed and the first comprehensive reaction mechanism for a photochemical C-H activating organometallic complex is presented.

  8. Molecular dynamics study of aqueous solvation dynamics following OClO photoexcitation

    E-Print Network [OSTI]

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

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

    E-Print Network [OSTI]

    Mohseni, Hooman

    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

  10. ULTRAFAST OPTICS AND OPTICAL FIBER COMMUNICATIONS LABORATORYLEOS 2003 Multiple Output Channel

    E-Print Network [OSTI]

    Purdue University

    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

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

    E-Print Network [OSTI]

    Marjoribanks, Robin S.

    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

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

    E-Print Network [OSTI]

    Monroe, Christopher

    , 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

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

    E-Print Network [OSTI]

    Peinke, Joachim

    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

  14. 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

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

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    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

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

    E-Print Network [OSTI]

    Dumitrica,Traian

    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

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

    E-Print Network [OSTI]

    Umstadter, Donald

    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

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

    E-Print Network [OSTI]

    Boyer, Edmond

    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

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

    E-Print Network [OSTI]

    Purdue University

    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

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

    SciTech Connect (OSTI)

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

    2009-05-01T23:59:59.000Z

    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.

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

    SciTech Connect (OSTI)

    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

    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.

  2. Semiglobal Simplex Optimization and Its Application to Determining the Preferred Solvation Sites of Proteins

    E-Print Network [OSTI]

    Vajda, Sandor

    Semiglobal Simplex Optimization and Its Application to Determining the Preferred Solvation Sites simplex method is extended into the Semiglobal Simplex (SGS) algorithm. Although SGS does not guarantee of the simplex algorithm, and thus, similarly to the Convex Global Underestimator (CGU) method, the search

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

    E-Print Network [OSTI]

    Collum, David B.

    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

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

    E-Print Network [OSTI]

    Collum, David B.

    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

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

    SciTech Connect (OSTI)

    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

    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.

  6. Solvation and Acid Strength Effects on Catalysis by Faujasite Zeolites

    SciTech Connect (OSTI)

    Gounder, Rajamani P.; Jones, Andrew J.; Carr, Robert T.; Iglesia, Enrique

    2012-02-01T23:59:59.000Z

    Kinetic, spectroscopic, and chemical titration data indicate that differences in monomolecular isobutane cracking and dehydrogenation and methanol dehydration turnover rates (per H+) among FAU zeolites treated thermally with steam (H-USY) and then chemically with ammonium hexafluorosilicate (CDHUSY) predominantly reflect differences in the size and solvating properties of their supercage voids rather than differences in acid strength. The number of protons on a given sample was measured consistently by titrations with Na+, with CH3 groups via reactions of dimethyl ether, and with 2,6-di-tert-butylpyridine during methanol dehydration catalysis; these titration values were also supported by commensurate changes in acidic OH infrared band areas upon exposure to titrant molecules. The number of protons, taken as the average of the three titration methods, was significantly smaller than the number of framework Al atoms (Alf) obtained from X-ray diffraction and 27Al magic angle spinning nuclear magnetic resonance spectroscopy on H-USY (0.35 H+/Alf) and CD-HUSY (0.69 H+/Alf). These data demonstrate that the ubiquitous use of Alf sites as structural proxies for active H+ sites in zeolites can be imprecise, apparently because distorted Al structures that are not associated with acidic protons are sometimes detected as Alf sites. Monomolecular isobutane cracking and dehydrogenation rate constants, normalized non-rigorously by the number of Alf species, decreased with increasing Na+ content on both H-USY and CD-HUSY samples and became undetectable at sub-stoichiometric exchange levels (0.32 and 0.72 Na+/Alf ratios, respectively), an unexpected finding attributed incorrectly in previous studies to the presence of minority ‘‘super-acidic’’ sites. These rate constants, when normalized rigorously by the number of residual H+ sites were independent of Na+ content on both H-USY and CD-HUSY samples, reflecting the stoichiometric replacement of protons that are uniform in reactivity by Na+ cations. Monomolecular isobutane cracking and dehydrogenation rate constants (per H+; 763 K), however, were higher on H-USY than CD-HUSY (by a factor of 1.4). Equilibrium constants for the formation of protonated methanol dimers via adsorption of gaseous methanol onto adsorbed methanol monomers, determined from kinetic studies of methanol dehydration to dimethyl ether (433 K), were also higher on H-USY than CD-HUSY (by a factor of 2.1). These larger constants predominantly reflect stronger dispersive interactions in H-USY, consistent with its smaller supercage voids that result from the occlusion of void space by extraframework Al (Alex) residues. These findings appear to clarify enduring controversies about the mechanistic interpretation of the effects of Na+ and Alex species on the catalytic reactivity of FAU zeolites. They also illustrate the need to normalize rates by the number of active sites instead of more convenient but less accurate structural proxies for such sites.

  7. Ultrafast reduction of the total magnetization in iron

    SciTech Connect (OSTI)

    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

    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.

  8. Reaction rate prediction for elementary reactions in binary mixed solvents assuming an additive solvation of reactant(s)

    E-Print Network [OSTI]

    Van Woert, Howard Clark

    1976-01-01T23:59:59.000Z

    REACTION RATE PREDICTION FOR ELEMENTARY REACTIONS IN BINARY MIXED SOLVENTS ASSUMING AN ADDITIVE SOLVATION OF REACTANT(S) A Thesis by HOWARD CLARK VAN WOERT, JR. Submitted to the Graduate College of Texas AkN University in partial fulfillment... of the requirement for the degree of MASTER OF SCIENCE August 1976 Major Subject: Chemistry REACTION RATE PREDICTION FOR ELEMENTARY REACTIONS IN BINARY MIXED SOLVENTS ASSUMING AN ADDITIVE SOLVATION OF REACTANT(S) A Thesis HOWARD CLARK VAN WOERT, JR. Approved...

  9. Ultrafast control of strong-field electron dynamics in solids

    E-Print Network [OSTI]

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

    2015-02-17T23:59:59.000Z

    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.

  10. Ultrafast Electron Dynamics in Low-Dimensional Materials

    E-Print Network [OSTI]

    Wolf, Martin

    ., PRB 76 (2007)] #12;Die unbesetzten QWS in Pb/Si(111) Vergleich zu DFT Rechnung [Wei and Chou. PRB 66 and Chou. PRB 66 (2002)] Freistehender Pb-Film Gute ¨Ubereinstimmung f¨ur besetzte QWS Systematische

  11. Ultrafast optical studies of electronic dynamics in semiconductors

    E-Print Network [OSTI]

    Ruzicka, Brian Andrew

    2012-05-31T23:59:59.000Z

    to their limited temporal resolution, electron measurement techniques cannot be used to study these processes on time scales in which the carrier-lattice system is not in equilibrium. However, in contemporary semiconductor devices with nanometer dimensions...

  12. 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: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level:Energy: Grid Integration Redefining What'sis Taking Over OurThe Iron Spin TransitionProgram |Frank CasellaEnergyUltracold Atoms: How

  13. 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: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level:Energy: Grid Integration Redefining What'sis Taking Over OurThe Iron Spin TransitionProgram |Frank CasellaEnergyUltracold Atoms:

  14. 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: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level:Energy: Grid Integration Redefining What'sis Taking Over OurThe Iron Spin TransitionProgram |Frank CasellaEnergyUltracold

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

    E-Print Network [OSTI]

    Purdue University

    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

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

    SciTech Connect (OSTI)

    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

    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}.

  17. 5D Data Storage by Ultrafast Laser Nanostructuring in Glass

    E-Print Network [OSTI]

    Anderson, Jim

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

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

    DOE Patents [OSTI]

    Smirl, A.; Trebino, R.P.

    1999-08-10T23:59:59.000Z

    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.

  19. Science Challenge Computational modeling of ultrafast digital electronics

    E-Print Network [OSTI]

    Freericks, Jim

    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

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

    SciTech Connect (OSTI)

    Cotoros, Ingrid A.

    2008-12-12T23:59:59.000Z

    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.

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

    E-Print Network [OSTI]

    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

    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.

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

    SciTech Connect (OSTI)

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

    1986-01-01T23:59:59.000Z

    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.

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

    E-Print Network [OSTI]

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

    2015-01-01T23:59:59.000Z

    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...

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

    E-Print Network [OSTI]

    Neumark, Daniel M.

    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

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

    SciTech Connect (OSTI)

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

    2014-12-01T23:59:59.000Z

    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.

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

    SciTech Connect (OSTI)

    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

    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.

  7. Ultrafast time-division demultiplexing of polarization-entangled photons

    E-Print Network [OSTI]

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

    2014-10-16T23:59:59.000Z

    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.

  8. Broadband laser cooling of trapped atoms with ultrafast pulses

    E-Print Network [OSTI]

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

    2005-07-07T23:59:59.000Z

    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.

  9. ULTRACAM - an ultra-fast, triple-beam CCD camera

    E-Print Network [OSTI]

    Vik Dhillon; Tom Marsh; the ULTRACAM team

    2001-10-01T23:59:59.000Z

    ULTRACAM is an ultra-fast, triple-beam CCD camera which has been designed to study one of the few remaining unexplored regions of observational parameter space - high temporal resolution. The camera will see first light in Spring 2002, at a total cost of GBP 300 k, and will be used on 2-m, 4-m and 8-m class telescopes to study astrophysics on the fastest timescales.

  10. Ultrafast Time-Resolved Electron Diffraction with Megavolt Electron Beams

    SciTech Connect (OSTI)

    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

    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.

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

    E-Print Network [OSTI]

    Allen, Roland E.

    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

  12. 1966 JOURNAL OF LIGHTWAVE TECHNOLOGY, VOL. 15, NO. 10, OCTOBER 1997 Mode Conversion of Ultrafast Pulses by Grating

    E-Print Network [OSTI]

    Ziolkowski, Richard W.

    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

  13. Ultrafast laser ablation ICP-MS: role of spot size, laser fluence, and repetition rate in signal intensity

    E-Print Network [OSTI]

    Harilal, S. S.

    Ultrafast laser ablation ICP-MS: role of spot size, laser fluence, and repetition rate in signal,a Richard E. Russob and Ahmed Hassaneina Ultrafast laser ablation inductively coupled plasma mass system. Though ultrafast laser ablation sample introduction provides better accuracy and precision

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

    E-Print Network [OSTI]

    KuÂ?el, Petr

    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

  15. 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]

    Jayaram, Bhyravabotla

    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

  16. 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]

    Goddard III, William A.

    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

  17. 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]

    Neumark, Daniel M.

    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

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

    E-Print Network [OSTI]

    Doster, Wolfgang

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

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

    SciTech Connect (OSTI)

    Dibya, Pooja Arora

    2010-05-16T23:59:59.000Z

    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.

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

    E-Print Network [OSTI]

    Longhua Hu; Alexander Y. Grosberg

    2007-01-24T23:59:59.000Z

    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.

  1. Analytic model of electron pulse propagation in ultrafast electron diffraction experiments

    E-Print Network [OSTI]

    Sipe,J. E.

    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

  2. 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

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

    E-Print Network [OSTI]

    Wang, Xiao-Ping

    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

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

    E-Print Network [OSTI]

    Loss, Daniel

    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

  5. 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

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

    E-Print Network [OSTI]

    von der Linde, D.

    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

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

    E-Print Network [OSTI]

    Röder, Beate

    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

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

    E-Print Network [OSTI]

    Fayer, Michael D.

    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

  9. RADIATION HEAT TRANSFER IN TISSUE WELDING AND SOLDERING WITH ULTRAFAST LASERS

    E-Print Network [OSTI]

    Guo, Zhixiong "James"

    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

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

    E-Print Network [OSTI]

    Kleinfeld, David

    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

  11. Time Resolved Photoelectron Imaging of Electronic Relaxation Dynamics in Anionic Clusters

    E-Print Network [OSTI]

    Griffin, Graham Bailey

    2009-01-01T23:59:59.000Z

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

  12. 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

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

    E-Print Network [OSTI]

    Fayer, Michael D.

    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

  14. Solvate Structures and Computational/Spectroscopic Characterization of LiBF4 Electrolytes

    SciTech Connect (OSTI)

    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

    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.

  15. Solvation Energies of Amino Acid Side Chains and Backbone in a Family of Host-Guest Pentapeptides

    E-Print Network [OSTI]

    Wimley, William C.

    octanol-water partitioning data. The free energy Gsc of transferring amino side chains from an organic & Tanford, 1971), the free energies of transfer of acetyl amino acid amides (Ac-X-amide) from octanol solvation parameters (ASP),1 which involves parameterizing the octanol-to-water transfer free energies

  16. Ultrafast pulsed laser utilizing broad bandwidth laser glass

    DOE Patents [OSTI]

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

    1997-01-01T23:59:59.000Z

    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.

  17. Rise time measurement for ultrafast X-ray pulses

    DOE Patents [OSTI]

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

    2005-04-05T23:59:59.000Z

    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.

  18. Photoionisation loading of large Sr+ ion clouds with ultrafast pulses

    E-Print Network [OSTI]

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

    2008-12-05T23:59:59.000Z

    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.

  19. Ultrafast laser control of backward superfluorescence towards standoff sensing

    SciTech Connect (OSTI)

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

    2014-01-13T23:59:59.000Z

    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)

  20. Ultrafast pulsed laser utilizing broad bandwidth laser glass

    DOE Patents [OSTI]

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

    1997-09-02T23:59:59.000Z

    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.

  1. Rise Time Measurement for Ultrafast X-Ray Pulses

    DOE Patents [OSTI]

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

    2005-04-05T23:59:59.000Z

    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.

  2. Optical Damage Threshold of Silicon for Ultrafast Infrared Pulses

    SciTech Connect (OSTI)

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

    2007-11-28T23:59:59.000Z

    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.

  3. Attosecond X-Ray Pulses for Molecular Electronic Dynamics

    E-Print Network [OSTI]

    Abel, Mark Joseph

    2010-01-01T23:59:59.000Z

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

  4. Single shot dynamic ellipsometry mesaurements of laser-driven shock waves

    SciTech Connect (OSTI)

    Bolme, C. A. [Department of Chemistry, Massachusetts Institute of Technology, Cambridge MA 02139 (United States)

    2007-12-12T23:59:59.000Z

    A technique has been developed to measure the time-resolved position of a laser-driven shock wave and the subsequent material flow. Ultrafast dynamic ellipsometry, using a chirped femtosecond laser pulse, probes picosecond material dynamics in a single shot by capitalizing on the refractive index changes in the shocked material. For transparent materials, the shock velocity, the particle velocity, and the shocked material's refractive index are extracted. Hugoniot data for poly(chlorotrifluoroethylene-co-vinylidene fluoride) (Kel-F 800) was obtained using ultrafast dynamic ellipsometry, and the data agrees well with previous data on macroscopic samples obtained in plate impact gas gun experiments.

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

    E-Print Network [OSTI]

    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

    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...

  6. Development of ZnO:Ga as an Ultrafast Scintillator

    SciTech Connect (OSTI)

    Bourret-Courchesne, E.D.; Derenzo, S.E.; Weber, M.J.

    2008-12-10T23:59:59.000Z

    We report on several methods for synthesizing the ultra-fast scintillator ZnO(Ga), and measurements of the resulting products. This material has characteristics that make it an excellent alpha detector for tagging the time and direction of individual neutrons produced by t-d and d-d neutron generators (associated particle imaging). The intensity and decay time are strongly dependent on the method used for dopant incorporation. We compare samples made by diffusion of Ga metal to samples made by solid state reaction between ZnO and Ga2O3 followed by reduction in hydrogen. The latter is much more successful and has a pure, strong near-band-edge fluorescence and an ultra-fast decay time of the x-ray-excited luminescence. The luminescence increases dramatically as the temperature is reduced to 10K. We also present results of an alternate low-temperature synthesis that produces luminescent particles with a more uniform size distribution. We examine possible mechanisms for the bright near-band-edge scintillation and favor the explanation that it is due to the recombination of Ga3+ donor electrons with ionization holes trapped on H+ ion acceptors.

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

    SciTech Connect (OSTI)

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

    2012-12-07T23:59:59.000Z

    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.

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

    SciTech Connect (OSTI)

    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

    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.

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

    E-Print Network [OSTI]

    Reich, Hans J.

    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

  10. Ultrafast K{alpha} x-ray Thomson scattering from shock compressed lithium hydride

    SciTech Connect (OSTI)

    Kritcher, A. L. [L-399, Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94551 (United States); Nuclear Engineering Department, University of California Berkeley, Berkeley, California 94709 (United States); Neumayer, P.; Castor, J.; Doeppner, T.; Landen, O. L.; Ng, A.; Pollaine, S.; Price, D.; Glenzer, S. H. [L-399, Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94551 (United States); Falcone, R. W.; Lee, H. J. [Physics Department, University of California Berkeley, Berkeley, California 94709 (United States); Lee, R. W. [L-399, Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94551 (United States); Physics Department, University of California Berkeley, Berkeley, California 94709 (United States); Holst, B.; Redmer, R. [Institut fuer Physik, Universitaet Rostock, D-18051 Rostock (Germany); Morse, E. C. [Nuclear Engineering Department, University of California Berkeley, Berkeley, California 94709 (United States)

    2009-05-15T23:59:59.000Z

    Spectrally and temporally resolved x-ray Thomson scattering using ultrafast Ti K{alpha} x rays has provided experimental validation for modeling of the compression and heating of shocked matter. The coalescence of two shocks launched into a solid density LiH target by a shaped 6 ns heater beam was observed from rapid heating to temperatures of 2.2 eV, enabling tests of shock timing models. Here, the temperature evolution of the target at various times during shock progression was characterized from the intensity of the elastic scattering component. The observation of scattering from plasmons, electron plasma oscillations, at shock coalescence indicates a transition to a dense metallic plasma state in LiH. From the frequency shift of the measured plasmon feature the electron density was directly determined with high accuracy, providing a material compression of a factor of 3 times solid density. The quality of data achieved in these experiments demonstrates the capability for single shot dynamic characterization of dense shock compressed matter. The conditions probed in this experiment are relevant for the study of the physics of planetary formation and to characterize inertial confinement fusion targets for experiments such as on the National Ignition Facility, Lawrence Livermore National Laboratory.

  11. Ultrafast K-(alpha) X-ray Thomson Scattering from Shock Compressed Lithium Hydride

    SciTech Connect (OSTI)

    Kritcher, A L; Neumayer, P; Castor, J; Doeppner, T; Falcone, R W; Landen, O L; Lee, H J; Lee, R W; Holst, B; Redmer, R; Morse, E C; Ng, A; Pollaine, S; Price, D; Glenzer, S H

    2008-12-10T23:59:59.000Z

    Spectrally and temporally resolved x ray Thomson scattering using ultrafast Ti K-{alpha} x-rays has provided experimental validation for modeling of the compression and heating of shocked matter. The coalescence of two shocks launched into a solid density LiH target by a shaped 6 nanosecond heater beam was observed from rapid heating to temperatures of 2.2 eV, enabling tests of shock timing models. Here, the temperature evolution of the target at various times during shock progression was characterized from the intensity of the elastic scattering component. The observation of scattering from plasmons, electron plasma oscillations, at shock coalescence indicates a transition to a dense metallic plasma state in LiH. From the frequency shift of the measured plasmon feature the electron density was directly determined with high accuracy, providing a material compression of a factor of three times solid density. The quality of data achieved in these experiments demonstrates the capability for single-shot dynamic characterization of dense shock compressed matter. The conditions probed in this experiment are relevant for the study of the physics of planetary formation and to characterize inertial confinement fusion targets for experiments such as on the National Ignition Facility (NIF), LLNL.

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

    E-Print Network [OSTI]

    Arima, Kenta

    2011-01-01T23:59:59.000Z

    Water adsorption, solvation and deliquescence of alkali94720, USA Abstract The adsorption of water on KBr thinBr and Cl, but not for F upon adsorption of water and after

  13. Measurement of Solvation Responses at Multiple Sites in a Globular Protein Paul Abbyad, Xinghua Shi, William Childs, Tim B. McAnaney, Bruce E. Cohen, and

    E-Print Network [OSTI]

    Boxer, Steven G.

    in biological processes including electron3,4 and proton transfer,5 enzyme catalysis,6 ligand binding,7 and ion protein are more complex due to its tertiary structure and heterogeneity, and solvation occurs on many

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

    E-Print Network [OSTI]

    Alper, Joshua Daniel

    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 ...

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

    E-Print Network [OSTI]

    Balasubramanian, Haribhaskar

    2009-05-15T23:59:59.000Z

    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...

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

    E-Print Network [OSTI]

    Wang, Yihua

    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 ...

  17. Ultrafast Cooperative Phenomena in Coherently Prepared Media: From Superfluorescence to Coherent Raman Scattering and Applications 

    E-Print Network [OSTI]

    Gombojav, Ariunbold

    2012-07-16T23:59:59.000Z

    Technological progress in commercializing ultrafast lasers and detectors has allowed realization of cooperative processes on an ultrashort time scale, which demand a re-evaluation of the conventional cooperative phenomena with a new insight...

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

    E-Print Network [OSTI]

    Balasubramanian, Haribhaskar

    2009-05-15T23:59:59.000Z

    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...

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

    E-Print Network [OSTI]

    Balasubramanian, Haribhaskar

    2008-10-10T23:59:59.000Z

    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...

  20. Sub-femtosecond precision timing distribution, synchronization and coherent synthesis of ultrafast lasers

    E-Print Network [OSTI]

    Cox, Jonathan A

    2012-01-01T23:59:59.000Z

    In this thesis, we present a complete set of techniques for sub-femtosecond measurement, control and distribution of ultrafast optical pulse trains, with respect to pulse timing and phase. First, analytical analysis of the ...

  1. Electromagnetically-driven ultra-fast tool servos for diamond turning

    E-Print Network [OSTI]

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

    2005-01-01T23:59:59.000Z

    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 ...

  2. Localized Excited Charge Carriers Generate Ultrafast Inhomogeneous Strain in the Multiferroic BiFeO3

    E-Print Network [OSTI]

    Evans, Paul G.

    Materialien und Energie GmbH, Wilhelm-Conrad-Röntgen Campus, BESSY II, Albert-Einstein-Straße 15, 12489 Berlin in a recent synchrotron-based ultrafast x-ray diffraction (UXRD) study with a temporal resolution of 100 ps

  3. Ultrafast Laser Induced Thermo-Elasto-Visco-Plastodynamics in Single Crystalline Silicon 

    E-Print Network [OSTI]

    Qi, Xuele

    2011-02-22T23:59:59.000Z

    A comprehensive model for describing the fundamental mechanism dictating the interaction of ultrafast laser pulse with single crystalline silicon wafer is formulated. The need for establishing the feasibility of employing lasers of subpicosecond...

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

    E-Print Network [OSTI]

    Nicodemus, Rebecca A.

    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), ...

  5. Reweighted ensemble dynamics simulations: theory, improvement, and application

    E-Print Network [OSTI]

    Linchen Gong; Xin Zhou; Zhong-Can Ou-Yang

    2015-02-22T23:59:59.000Z

    Based on multiple parallel short molecular dynamics simulation trajectories, we designed the reweighted ensemble dynamics (RED) method to more efficiently sample complex (biopolymer) systems, and to explore their hierarchical metastable states. Here we further present an improvement to depress statistical errors of the RED and we discuss a few keys in practical application of the RED, provides schemes on selection of basis functions, determination of free parameter in the RED. We illustrate the application of the improvements in two toy models and in the solvated alanine dipeptide. The results show the RED enable to capture the topology of multiple-state transition networks, to detect the diffusion-like dynamical behavior in entropy-dominated system, and to identify solvent effects in the solvated peptides. The illustrations serve as general applications of the RED in more complex biopolymer systems.

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

    E-Print Network [OSTI]

    Fayer, Michael D.

    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

  7. Solvation studies on anion radicals of alkyl nitrobenzene derivatives in acetonitrile-alkyl alcohol solvent mixtures at 25 p0 sC

    E-Print Network [OSTI]

    Chu, William Wen-Chen

    1970-01-01T23:59:59.000Z

    SOLVATION STUDIES OM ANION RADICALS QF ALKYL NITROBENZENE DERIVATIVES IN ACETONITRILE- ALKYL ALCOHOL SOLVENT MIXTURES AT PS C A Thesis by WILLIAM WEN CHEN CHU Submitted to the Graduate College of Texas ASM University in partial fulfillment... of the requirement for the degree of MASTER OF SCIENCE August 1970 Ma)or Sub)oct: Chemistry SOLVATION STUDIES ON ANION RADICALS OF ALKYL NITROBENZENE DERIVATIVES IN ACETONITRILE- ALKYL ALCOHOL SOLVENT MIXTURES AT 25'C A Thesis NILLIAM HEN-CHEN CHU Approved...

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

    E-Print Network [OSTI]

    Balasubramanian, Haribhaskar

    2008-10-10T23:59:59.000Z

    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...

  9. Performance of volume phase gratings manufactured using ultrafast laser inscription

    E-Print Network [OSTI]

    Lee, David; Cunningham, Colin R

    2012-01-01T23:59:59.000Z

    Ultrafast laser inscription (ULI) is a rapidly maturing technique which uses focused ultrashort laser pulses to locally modify the refractive index of dielectric materials in three-dimensions (3D). Recently, ULI has been applied to the fabrication of astrophotonic devices such as integrated beam combiners, 3D integrated waveguide fan-outs and multimode-to-single mode convertors (photonic lanterns). Here, we outline our work on applying ULI to the fabrication of volume phase gratings (VPGs) in fused silica and gallium lanthanum sulphide (GLS) glasses. The VPGs we fabricated had a spatial frequency of 333 lines/mm. The optimum fused silica grating was found to exhibit a first order diffraction efficiency of 40 % at 633 nm, but exhibited approximately 40 % integrated scattered light. The optimum GLS grating was found to exhibit a first order diffraction efficiency of 71 % at 633 nm and less than 5 % integrated scattered light. Importantly for future astronomy applications, both gratings survived cooling to 20 K....

  10. Ultrafast stimulated Raman parallel adiabatic passage by shaped pulses

    E-Print Network [OSTI]

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

    2009-10-06T23:59:59.000Z

    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.

  11. Ultrafast electron diffraction with radio-frequency compressed electron pulses

    SciTech Connect (OSTI)

    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

    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.

  12. Ultrafast laser diagnostics to investigate initiation fundamentals in energetic materials.

    SciTech Connect (OSTI)

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

    2013-08-01T23:59:59.000Z

    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.

  13. Ultrafast Extreme Ultraviolet Induced Isomerization of Acetylene Cations

    SciTech Connect (OSTI)

    Jiang, Y. H.; Kurka, M.; Kuehnel, K. U.; Schroeter, C. D.; Moshammer, R. [Max-Planck-Institut fuer Kernphysik, 69117 Heidelberg (Germany); Rudenko, A.; Foucar, L. [Max-Planck Advanced Study Group at CFEL, 22607 Hamburg (Germany); Herrwerth, O.; Lezius, M.; Kling, M. F. [Max-Planck-Institut fuer Quantenoptik, 85748 Garching (Germany); Tilborg, J. van; Belkacem, A. [Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Ueda, K. [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, 980-8577 Sendai (Japan); Duesterer, S.; Treusch, R. [DESY, 22607 Hamburg (Germany); Ullrich, J. [Max-Planck-Institut fuer Kernphysik, 69117 Heidelberg (Germany); Max-Planck Advanced Study Group at CFEL, 22607 Hamburg (Germany)

    2010-12-31T23:59:59.000Z

    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

  14. Ultrafast Extreme Ultraviolet Induced Isomerization of Acetylene Cations

    SciTech Connect (OSTI)

    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

    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.

  15. A pulsed electron gun for ultrafast electron diffraction at surfaces

    SciTech Connect (OSTI)

    Janzen, A.; Krenzer, B.; Heinz, O.; Zhou, P.; Thien, D.; Hanisch, A.; Meyer zu Heringdorf, F.-J.; Linde, D. von der; Horn von Hoegen, M. [Department of Physics and Centre for Nanointegration (CeNIDE), University of Duisburg-Essen, 47048 Duisburg (Germany)

    2007-01-15T23:59:59.000Z

    The construction of a pulsed electron gun for ultrafast reflection high-energy electron diffraction experiments at surfaces is reported. Special emphasis is placed on the characterization of the electron source: a photocathode, consisting of a 10 nm thin Au film deposited onto a sapphire substrate. Electron pulses are generated by the illumination of the film with ultraviolet laser pulses of femtosecond duration. The photoelectrons are emitted homogeneously across the photocathode with an energy distribution of 0.1 eV width. After leaving the Au film, the electrons are accelerated to kinetic energies of up to 15 keV. Focusing is accomplished by an electrostatic lens. The temporal resolution of the experiment is determined by the probing time of the electrons traveling across the surface which is about 30 ps. However, the duration of the electron pulses can be reduced to less than 6 ps.

  16. Dynamic

    Office of Legacy Management (LM)

    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: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645 3,625 1,006 492 742EnergyOn AprilA group currentBradleyTableSelling7111AWell: Gas productionDynamic , and Static ,

  17. Probing Reaction Dynamics of Transition-Metal Complexes in Solution via Time-Resolved Soft X-ray Spectroscopy

    SciTech Connect (OSTI)

    Huse, Nils; Kim, Tae Kyu; Khalil, Munira; Jamula, Lindsey; McCusker, James K.; Schoenlein, Robert W.

    2010-05-02T23:59:59.000Z

    We report the first time-resolved soft x-ray measurements of solvated transition-metal complexes. L-edge spectroscopy directly probes dynamic changes in ligand-field splitting of 3d orbitals associated with the spin transition, and mediated by changes in ligand-bonding.

  18. Semiclassical molecular dynamics simulations of ultrafast photodissociation dynamics associated with the Chappuis band of ozone

    E-Print Network [OSTI]

    Miller, William H.

    with the Chappuis band of ozone Victor S. Batista and William H. Millera) Department of Chemistry, University A ) of ozone following photoexcitation of the molecule in the gas phase with visible light. Our algorithm and recurrence events, as well as an interpretation of experimental studies of the Chappuis band of ozone

  19. Third-order many-body perturbation theory applied to Kondo-type dynamics in diluted magnetic semiconductors

    E-Print Network [OSTI]

    Boyer, Edmond

    Ultrafast magnetization dynamics in diluted magnetic semiconductors is investigated using a model based, demagnetization processes in di- luted magnetic semiconductors DMS .3 In particular, one of the most frequentlyThird-order many-body perturbation theory applied to Kondo-type dynamics in diluted magnetic

  20. Co-nonsolvency of PNiPAM at the transition between solvation mechanisms

    E-Print Network [OSTI]

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

    2014-10-28T23:59:59.000Z

    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.

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

    SciTech Connect (OSTI)

    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

    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.

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

    E-Print Network [OSTI]

    Boyer, Edmond

    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

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

    E-Print Network [OSTI]

    Harilal, S. S.

    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

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

    E-Print Network [OSTI]

    von der Linde, D.

    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

  5. Dynamical Casimir Effect in Quantum Information Processing

    E-Print Network [OSTI]

    Giuliano Benenti; Antonio D'Arrigo; Stefano Siccardi; Giuliano Strini

    2014-07-28T23:59:59.000Z

    We demonstrate, in the regime of ultrastrong matter-field coupling, the strong connection between the dynamical Casimir effect (DCE) and the performance of quantum information protocols. Our results are illustrated by means of a realistic quantum communication channel and show that the DCE is a fundamental limit for quantum computation and communication and that novel schemes are required to implement ultrafast and reliable quantum gates. Strategies to partially counteract the DCE are also discussed.

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

    E-Print Network [OSTI]

    Brandt, Rebekah Katherine

    2012-01-01T23:59:59.000Z

    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

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

    SciTech Connect (OSTI)

    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

    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.

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

    SciTech Connect (OSTI)

    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

    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.

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

    E-Print Network [OSTI]

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

    2015-01-01T23:59:59.000Z

    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.

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

    SciTech Connect (OSTI)

    Peter Pronko

    2004-12-13T23:59:59.000Z

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

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

    SciTech Connect (OSTI)

    Anna Lee Tonkovich

    2008-08-11T23:59:59.000Z

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

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

    SciTech Connect (OSTI)

    Wagner, A. Y.; Umemura, M. [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

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

  13. An ultrafast phase-change logic device driven by melting processes

    E-Print Network [OSTI]

    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

    /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...

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

    SciTech Connect (OSTI)

    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

    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.

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

    E-Print Network [OSTI]

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

    2002-03-31T23:59:59.000Z

    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.

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

    E-Print Network [OSTI]

    Fayer, Michael D.

    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

  17. A quantum-dynamical theory for nonlinear optical interactions in graphene

    E-Print Network [OSTI]

    Zheshen Zhang; Paul L. Voss

    2011-06-23T23:59:59.000Z

    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.

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

    SciTech Connect (OSTI)

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

    2014-08-20T23:59:59.000Z

    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.

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

    E-Print Network [OSTI]

    Peinke, Joachim

    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

  20. 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

  1. 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

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

    SciTech Connect (OSTI)

    Sterling Backus

    2012-05-14T23:59:59.000Z

    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.

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

    E-Print Network [OSTI]

    Kumar, Anand T.N.

    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

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

    E-Print Network [OSTI]

    Arizona, University of

    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

  5. Ultra-Fast Absorption of Amorphous Pure Drug Aerosols Via Deep Lung Inhalation

    E-Print Network [OSTI]

    Rabinowitz, Joshua D.

    Ultra-Fast Absorption of Amorphous Pure Drug Aerosols Via Deep Lung Inhalation JOSHUA D. RABINOWITZ inhalation. The speed of pulmonary drug absorption depends on the site of aerosol deposition within the lung incorporating this thermal aerosol technology, and its application to the delivery of alprazolam, an anti

  6. Ultrafast absorber saturation process and short pulse formation in injection lasers

    E-Print Network [OSTI]

    Buller, Gerald S.

    Ultrafast absorber saturation process and short pulse formation in injection lasers S. V. Zaitsev 1998 The nature of lasing threshold in passively Q-switched GaAs/AlGaAs lasers with saturable absorbers formed by heavy ion implantation is investigated in this article. After studying various laser

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

    E-Print Network [OSTI]

    Umstadter, Donald

    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

  8. Ultrafast shift and injection currents observed in wurtzite semiconductors via emitted terahertz radiation

    E-Print Network [OSTI]

    Van Driel, Henry M.

    Ultrafast shift and injection currents observed in wurtzite semiconductors via emitted terahertz; published online 18 November 2005 Shift and injection currents are generated in the wurtzite semiconductors in the wurtzite structure. The largest shift currents are generated along the optical axis for light polarized

  9. hal-00137243,version1-19Mar2007 High shock release in ultrafast laser irradiated metals

    E-Print Network [OSTI]

    Boyer, Edmond

    hal-00137243,version1-19Mar2007 High shock release in ultrafast laser irradiated metals: Scenario matter exposed to subpicosecond near infrared pulsed laser radiation. We point out to the role of strong of material exceeding the specific energy required for melting is reported for copper and aluminum

  10. Module Title: Solid state and ultrafast lasers Module Code: OPTO6002

    E-Print Network [OSTI]

    Anderson, Jim

    and techniques Heat generation and thermal management Power scaling strategies (cladding-pumping, MOP calculations on the operating parameter and output parameters of a wide variety of solid state and ultrafast efficiency, output power, gain Laser modes and resonator design Pump sources, pump delivery and coupling

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

    E-Print Network [OSTI]

    Borguet, Eric

    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

  12. Ultrafast Proton Shuttling in Psammocora Cyan Fluorescent Protein John T. M. Kennis,*,

    E-Print Network [OSTI]

    van Stokkum, Ivo

    Ultrafast Proton Shuttling in Psammocora Cyan Fluorescent Protein John T. M. Kennis,*, Ivo H. M-state proton transfer (ESPT) reactions. Recently, a novel cyan fluorescent protein (CFP) termed psamFP488 vicinity to the chromophore to act as a proton acceptor. Our findings support a model where unusually fast

  13. Ultrafast MR Grid-Tagging Sequence for Assessment of Local Mechanical Properties of the Lungs

    E-Print Network [OSTI]

    Napadow, Vitaly

    Ultrafast MR Grid-Tagging Sequence for Assessment of Local Mechanical Properties of the Lungs Qun in MR imaging of lung parenchyma. In this study, a fast MR grid-tagging technique is described deformation of the lung. Quantitative analysis of the data shows that this method is capable of assessing

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

    E-Print Network [OSTI]

    Bazant, Martin Z.

    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

  15. All-optical fiber-based devices for ultrafast amplitude jitter magnification

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    All-optical fiber-based devices for ultrafast amplitude jitter magnification Charles-Henri Hage-intercept PC with 0 jitter will increase [3]. We first jitter of a 10-GHz picosecond pulse train delivered by an actively mode-locked erbium doped fiber laser

  16. PHYSICAL REVIEW B 84, 094502 (2011) Nondeterministic ultrafast ground-state cooling of a mechanical resonator

    E-Print Network [OSTI]

    2011-01-01T23:59:59.000Z

    proposed a ground-state cooling scheme of an MR in an optomechanical system by controlling the opticalPHYSICAL REVIEW B 84, 094502 (2011) Nondeterministic ultrafast ground-state cooling of a mechanical Research Center, Beijing 100084, China 2 Department of Theoretical Physics and History of Science

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

    E-Print Network [OSTI]

    Wurtele, Jonathan

    HARMONIC CASCADE FEL DESIGNS FOR LUX, A FACILTY FOR ULTRAFAST X-RAY SCIENCE J. Corlett, W. Fawley. We also discuss lattice considerations pertinent to harmonic cascade FELs, somesensitivity studies. While much of this effort has been concentrated upon SASE-based FEL's, there is an alternative "harmonic

  18. Ultrafast optical nonlinearity in poly,,methylmethacrylate...-TiO2 nanocomposites

    E-Print Network [OSTI]

    Wei, Ji

    -quality, transparent films consisting of polymer-TiO2 hybrid nanocomposites, and on their linear optical properties.3Ultrafast optical nonlinearity in poly,,methylmethacrylate...-TiO2 nanocomposites H. I. Elim and W nanocomposites, which are synthesized by a simple technique of in-situ sol-gel/polymerization. The best figures

  19. Shock-wave generation in transparent media from ultra-fast lasers R. Bernath*a

    E-Print Network [OSTI]

    Van Stryland, Eric

    Shock-wave generation in transparent media from ultra-fast lasers R. Bernath*a , C. G. Browna , J a harmonic of the pump laser frequency. Experiments also include burst-mode operation, where a train of ultra. Aspiotisa , M. Fishera , & M. Richardsona a Laser Plasma Laboratory, College of Optics & Photonics: CREOL

  20. 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)

    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

    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.

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

    E-Print Network [OSTI]

    Rini, M

    2010-01-01T23:59:59.000Z

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

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

    SciTech Connect (OSTI)

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

    2008-07-07T23:59:59.000Z

    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.

  3. 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

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

    E-Print Network [OSTI]

    Cox, Jonathan A.

    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 ...

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

    E-Print Network [OSTI]

    Bauer, Michael

    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

  6. A novel ultra-fast parallel algorithm for image compression using semi-orthogonal spline boundary wavelets

    E-Print Network [OSTI]

    Mishra, Deepam

    1995-01-01T23:59:59.000Z

    A NOVEL ULTRA-FAST PARALLEL ALGORITHM FOR IMAGE COMPRESSION USING SEMI-ORTHOGONAL SPLINE BOUNDARY WAVELETS A Thesis by DEEPAM MISHRA Submitted to the Office of Graduate Studies of Texas ARM University in partial fulfillment... Yurt tps (Member) A. D. P tton (Head of D artment) December 1995 Major Subject: Electrical Engineering 111 ABSTRACT A Novel Ultra-Fast Parallel Image Compression Algorithm Using Spline Boundary Wavelets. (December 1995) Deepam Mishra, B. Tech...

  7. LCLS Ultrafast Science Instruments:Conceptual Design Report

    SciTech Connect (OSTI)

    Arthur, J.; Boutet, S.; Castagna, J-C.; Chapman, H.; Feng, Y.; Foyt, W.; Fritz, D.M.; Gaffney, K.J.; Gr|bel, G.; Hajdu, J.; Hastings, J.B.; Kurita, N.; Larsson, J.; Ludwig, K.; Messerschmidt, M.; Miao, J.; Reis, D.A.; Robert, A.; Stephenson, G.B.; Tschentscher, Th.; van Bakel, N.; /SLAC /LLNL, Livermore /DESY /Lund Inst. Tech. /Boston U. /UCLA /Michigan U. /Argonne

    2007-10-16T23:59:59.000Z

    The Stanford Linear Accelerator Center (SLAC), along with Argonne National Laboratory (ANL), Lawrence Livermore National Laboratory (LLNL), and the University of California at Los Angeles (UCLA), is constructing a Free-Electron Laser (FEL) facility, which will operate in the wavelength range 1.5 nm - 0.15 nm. This FEL, the Linac Coherent Light Source (LCLS), utilizes the SLAC linac and will produce sub-picosecond pulses of short wavelength X-rays with very high peak brightness and almost complete transverse coherence. The final one-third of the SLAC linac will be used as the source of electrons for the LCLS. The high energy electrons will be transported across the SLAC Research Yard, into a tunnel which will house a long undulator. In passing through the undulator, the electrons will be bunched by the force of their own synchrotron radiation and produce an intense, monochromatic, spatially coherent beam of X-rays. By varying the electron energy, the FEL X-ray wavelength will be tunable from 1.5 nm to 0.15 nm. The LCLS will include two experimental halls as well as X-ray optics and infrastructure necessary to create a facility that can be developed for research in a variety of disciplines such as atomic physics, materials science, plasma physics and biosciences. This Conceptual Design Report, the authors believe, confirms the feasibility of designing and constructing three X-ray instruments in order to exploit the unique scientific capability of this new LCLS facility. The technical objective of the LCLS Ultrafast Science Instruments (LUSI) project is to design, build, and install at the LCLS three hard X-ray instruments that will complement the initial instrument included in the LCLS construction. As the science programs advance and new technological challenges appear, instrumentation needs to be developed and ready to conquer these new opportunities. The LCLS instrument concepts have been developed in close consultation with the scientific community through a series of workshops team meetings and focused reviews. In particular, the LUSI project instruments have been identified as meeting the most urgent needs of the scientific community based on the advice of the LCLS Scientific Advisory Committee (SAC) in response to an open call for letters of intent (LOI) from the breadth of the scientific community.

  8. Upgrading Methane Using Ultra-Fast Thermal Swing Adsorption

    SciTech Connect (OSTI)

    Anna Lee Tonkovich

    2004-07-01T23:59:59.000Z

    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.

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

    E-Print Network [OSTI]

    Guidoni, Leonardo

    the decomposition of the vibrational density of states of the gas phase and solution dynamics. The calculated shifts the structural and dynamical aspects of water solutions. X-ray as well as neutron diffraction are the main source and electronic structure of the molecule.1 We expect therefore that also its vibrational properties could

  10. Ultra-fast underwater suction traps Olivier Vincenta

    E-Print Network [OSTI]

    Boyer, Edmond

    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

  11. 1462 J. Opt. Soc. Am. B/Vol. 5,No. 7/July 1988 Solvation dynamics in coherent and spontaneous Raman

    E-Print Network [OSTI]

    Mukamel, Shaul

    . INTRODUCTION Coherent Raman spectroscopy is a four-wave mixing tech- nique that provides a sensitive- nances (width back- ground (width -100 cm-1). This is similar to what (e.g., solution, solid matrices, and glasses) by using a stochastic theory of the nonlinear

  12. Tunable spin wave dynamics in two-dimensional Ni80Fe20 nanodot lattices by varying dot shape

    E-Print Network [OSTI]

    Otani, Yoshichika

    .1063/1.4890088] Potential applications of nanomagnets1 in magnetic data storage,2,3 memory,4 and logic5,6 devices as well in the ferromagnetic nanostructures. The ever increasing demand of miniaturization and speed of devices offers-chip microwave communi- cation devices attracted interest into the ultrafast magnetiza- tion dynamics

  13. Hydration structure of salt solutions from ab initio molecular dynamics

    SciTech Connect (OSTI)

    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

    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.

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

    SciTech Connect (OSTI)

    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

    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.

  15. 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]

    Kamerlin, Shina C. L.

    2009-01-01T23:59:59.000Z

    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

  16. Ultrafast Power Processor for Smart Grid Power Module Development

    SciTech Connect (OSTI)

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

    2012-12-30T23:59:59.000Z

    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.

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

    E-Print Network [OSTI]

    Samuel L Smith; Alex W Chin

    2014-06-04T23:59:59.000Z

    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.

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

    SciTech Connect (OSTI)

    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

    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.

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

    SciTech Connect (OSTI)

    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

    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.

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

    E-Print Network [OSTI]

    Jordi Mur-Petit; Juan José García-Ripoll

    2015-01-12T23:59:59.000Z

    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.

  1. DeepNet: An Ultrafast Neural Learning Code for Seismic Imaging

    SciTech Connect (OSTI)

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

    1999-07-10T23:59:59.000Z

    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.

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

    SciTech Connect (OSTI)

    Zheng, Buxiang; Jiang, Gedong; Wang, Wenjun, E-mail: wenjunwang@mail.xjtu.edu.cn; Wang, Kedian; Mei, Xuesong [School of Mechanical Engineering, Xi'an Jiaotong University, No. 28, Xianning Westroad, Xi'an 710049 (China) [School of Mechanical Engineering, Xi'an Jiaotong University, No. 28, Xianning Westroad, Xi'an 710049 (China); State Key Laboratory for Manufacturing Systems Engineering, Xi'an Jiaotong University, Xi'an 710054 (China)

    2014-03-15T23:59:59.000Z

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

  3. 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]

    Blinov, Boris

    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

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

    SciTech Connect (OSTI)

    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

    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.

  5. Ultrafast thermally induced magnetic switching in synthetic ferrimagnets

    SciTech Connect (OSTI)

    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

    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.

  6. Dynamics of excess electrons in atomic and molecular clusters

    E-Print Network [OSTI]

    Young, Ryan Michael

    2011-01-01T23:59:59.000Z

    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

  7. 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

  8. Energetics and structure in solvent: A dielectric continuum model of solvation combined with molecular mechanics, Ab Initio, and Semi-empirical molecular orbital treatments of the solute

    SciTech Connect (OSTI)

    Tawa, G.J. [Frederick Cancer Research and Development Center, MD (United States); Pratt, L.R.; Martin, R.L. [Los Alamos National Lab., NM (United States)

    1996-12-31T23:59:59.000Z

    We present a method for computing the electrostatic component of the solvation free energy, {Delta}G{sup el}, of a solute molecule in the presence of solvent modeled as a dielectric continuum. The method is based on an integral form of Poisson`s equation which is solved to obtain a distribution of induced polarization charge at the solute-solvent dielectric interface. The solution of Poisson`s equation is obtained by application of a boundary element procedure. The method is tested by comparing its predictions of {Delta}G{sup el} to exact values for several model problems. The method is then used in a variety of contexts to assess its qualitative prediction ability. It is first combined with a molecular mechanics treatment of the solute to evaluate the effects of aqueous solvent on the conformational equilibria of several small molecules of interest-these are N-methyl acetamide and alanine dipeptide. For both molecules dielectric continuum solvation predicts torsional free energies of solvation that are in accord with other more complete treatments of solvation. The method is then combined with ab initio and semi-empirical molecular orbital theory for the solute. Self consistent reaction field calculations (SCRF) are performed to evaluate the correlation is in general very good. Relative agreement with experiment is best for ions where electrostatics predominate and worst for non-polar neutral molecules were electrostatics are minor. Semi-empirical configuration interaction SCRF calculations are also performed in the presence of solvent in order to determine ground-to-excited state absorption energy shifts for formaldehyde and indole mine ground-to-excited state absorption energy shifts for formaldehyde and indole when placed in water. We find a rough correlation between transition energy shifts and the dipole moments of the initial and final states involved in the transition.

  9. Ultrafast Magnetization Dynamics of SrRuO3 Thin Films

    SciTech Connect (OSTI)

    Langner, Matthew C

    2009-05-19T23:59:59.000Z

    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.

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

    E-Print Network [OSTI]

    Osterloh, Frank

    and Methanol Elizabeth C. Carroll, Owen C. Compton, Dorte Madsen, Frank E. Osterloh, and Delmar S. Larsen-order kinetics on a sub-nanosecond time scale that depended on the nanosheet size. Methanol was used and methanol solutions. Methanol is known as an efficient sacrificial electron donor for layered metal oxide

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

    E-Print Network [OSTI]

    Hosler, Erik Robert

    2013-01-01T23:59:59.000Z

    Letters 329, 469 A. Rudenko, T. Ergler, B. Feuerstein, K.Ergler, B. Feuerstein, A. Rudenko, K. Zrost, C. D. Schroter,

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

    E-Print Network [OSTI]

    Wheeler, Damon Andreas

    2013-01-01T23:59:59.000Z

    W. Mourad; M. Rophael, Applied Catalysis B: Environmental,M. F. ; Takahashi, T. Applied Catalysis B: Self-assembledreactivity of TiO2. Applied Catalysis B: Environmental Doan,

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

    E-Print Network [OSTI]

    Wheeler, Damon Andreas

    2013-01-01T23:59:59.000Z

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

  14. Transient lattice dynamics in fs-laser-excited semiconductors probed by ultrafast x-ray diffraction

    E-Print Network [OSTI]

    von der Linde, D.

    K. Sokolowski-Tinten , M. Horn von Hoegen, D. von der Linde Inst. for Laser- and Plasmaphysics Hannover, Germany #12;K. Sokolowski-Tinten, M. Horn von Hoegen, D. von der Linde, A. Cavalleri, C.W. Siders

  15. Ultrafast relaxation dynamics of hot optical phonons in graphene Haining Wang,1,a

    E-Print Network [OSTI]

    Afshari, Ehsan

    of the coupled carrier-phonon system with rate equations and find a good agreement between the experimental data phonons which then present the main bottleneck to subsequent cooling. Optical phonon cooling on short time between 2­3 ps were reported for both zone-center E2g and zone-edge A1 modes for phonon temperatures

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

    E-Print Network [OSTI]

    Hosler, Erik Robert

    2013-01-01T23:59:59.000Z

    in construction, a CO 2 laser drilling platform designed by111 In addition to the laser drilling of the gas inlets, theas well as in the laser drilling of the fiber gas inlets

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

    E-Print Network [OSTI]

    Wheeler, Damon Andreas

    2013-01-01T23:59:59.000Z

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

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

    SciTech Connect (OSTI)

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

    2010-12-03T23:59:59.000Z

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

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

    E-Print Network [OSTI]

    Wheeler, Damon Andreas

    2013-01-01T23:59:59.000Z

    Yang, Z. ; Zhang, R. ; Cheng, Z. ; Elliot, A. M. ; Stafford,C. ; Wei, Z. G. ; Xie, S. G. ; Cheng, Z. J. ; Xiao, C. M. ,

  20. Ultrafast dynamics of hot electrons and holes in copper: Excitation, energy relaxation, and transport effects

    E-Print Network [OSTI]

    Wolf, Martin

    , and transport effects E. Knoesel, A. Hotzel, and M. Wolf Fritz-Haber-Institut der MPG, Faradayweg 4-6, D-14195 calculation, a simulation of the ballistic transport effect and its implication on the observed electron process for a hot electron is scattering with a ``cold'' elec- tron below the Fermi level, because

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

    E-Print Network [OSTI]

    Wheeler, Damon Andreas

    2013-01-01T23:59:59.000Z

    in hematite derived from goethite. 1979, 29, Li, D. ; Teoh,of Anion Adsorption on Goethite. 1987, 51, 54-56. (126)Amorphous Silica, and Goethite Surfaces. (136) Thimsen, E. ;

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

    E-Print Network [OSTI]

    Yang, H.

    2011-01-01T23:59:59.000Z

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

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

    E-Print Network [OSTI]

    Wheeler, Damon Andreas

    2013-01-01T23:59:59.000Z

    Solar Absorption for Photocatalysis with Black Hydrogenatedof physical Chemistry C Photocatalysis of Ag-Loaded TiO 2Lu, G. ; Yates, J. T. , Photocatalysis on TiO2 Surfaces:

  4. Lattice and Carrier Dynamics in Quantum-Confined Materials on Ultrafast

    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: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645U.S. DOE Office of Science (SC)Integrated Codes |Is Your HomeLatest News Releases Tribune carries magnetTimescales |

  5. Ultrafast Dynamic Response of Single Crystal PETN and Beta-HMX | SciTech

    Office of Scientific and Technical Information (OSTI)

    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: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645 3,625 1,006 492 742EnergyOnItem Not Found Item Not Found The item youThe DiscoveryFuels and Power5727MARCConnect

  6. A site-specific look at ultrafast interfacial electron dynamics | Stanford

    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: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645 3,625 1,006 492 742EnergyOnItem NotEnergy, science,SpeedingWu,IntelligenceYou are70 Years ofA BriefT

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

    ScienceCinema (OSTI)

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

    2011-11-02T23:59:59.000Z

    '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.

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

    SciTech Connect (OSTI)

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

    2009-10-15T23:59:59.000Z

    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.

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

    SciTech Connect (OSTI)

    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

    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.

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

    E-Print Network [OSTI]

    Wang, Yihua

    2013-01-01T23:59:59.000Z

    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.

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

    SciTech Connect (OSTI)

    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

    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.

  12. Single Photon Subradiance:Quantum control of spontaneous emission and ultrafast readout

    E-Print Network [OSTI]

    Marlan O. Scully

    2015-05-12T23:59:59.000Z

    Recent work has shown that collective single photon emission from an ensemble of resonate two-level atoms is a rich field of study. For example single photon superradiance from an extended ensemble yields enhanced directional spontaneous emission; and when the effects of the collective Lamb shift are included it becomes even more interesting. The present paper addresses the flip side of superradiance, i.e., subradiance. Single photon subradiant states are potentially stable against collective spontaneous emission and can have ultrafast readout. In particular, it is shown how many atom collective effects can be used to control emission by preparing and switching between subradiant and superradiant states.

  13. Ultrafast Materials and Chemical Sciences FOA | U.S. DOE Office of Science

    Office of Science (SC) Website

    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: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level:Energy: Grid Integration Redefining What'sis Taking Over OurTheBrookhaven NationalRegionals » High School(SC) The(SC) Ultrafast

  14. Ultrafast laser based coherent control methods for explosives detection

    SciTech Connect (OSTI)

    Moore, David Steven [Los Alamos National Laboratory

    2010-12-06T23:59:59.000Z

    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.

  15. Ultrafast UV Pump/IR Probe Studies of C-H Activation in Linear, Cyclic, and Aryl Hydrocarbons

    E-Print Network [OSTI]

    Harris, Charles B.

    Ultrafast UV Pump/IR Probe Studies of C-H Activation in Linear, Cyclic, and Aryl Hydrocarbons, cyclic, and aromatic hydrocarbon solvents on a femtosecond to microsecond time scale. These results have revealed that the structure of the hydrocarbon substrate affects the final C-H bond activation step, which

  16. REVIEW OF SCIENTIFIC INSTRUMENTS 84, 123906 (2013) A table-top, repetitive pulsed magnet for nonlinear and ultrafast

    E-Print Network [OSTI]

    Kono, Junichiro

    2013-01-01T23:59:59.000Z

    REVIEW OF SCIENTIFIC INSTRUMENTS 84, 123906 (2013) A table-top, repetitive pulsed magnet for nonlinear and ultrafast spectroscopy in high magnetic fields up to 30 T G. Timothy Noe II,1 Hiroyuki Nojiri and Computer Engineering, Rice University, Houston, Texas 77005, USA 2 Institute for Materials Research, Tohoku

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

    E-Print Network [OSTI]

    van Stokkum, Ivo

    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

  18. Controlling Graphene Ultrafast Hot Carrier Response from Metal-like to Semiconductor-like by Electrostatic Gating

    E-Print Network [OSTI]

    Zettl, Alex

    with dry nitrogen during the measurement. Sample preparation We grow single layer graphene on copper foil1 Controlling Graphene Ultrafast Hot Carrier Response from Metal-like to Semiconductor electro-optic sampling.2 The focused THz beam at our graphene sample has a diameter of 1 mm. For optical

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

    E-Print Network [OSTI]

    Yeh, Syun-Ru

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

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

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    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

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

    DOE Patents [OSTI]

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

    2011-03-22T23:59:59.000Z

    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.

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

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    Free electron properties of metals under ultrafast laser-induced electron-phonon nonequilibrium modelled based on the free electron classical theory, the free electron number is a key parameter. However or delocalized electronic states, temperature dependent free electron numbers are evaluated for a series

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

    SciTech Connect (OSTI)

    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

    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.

  4. Semiclassical analysis of quantum dynamics

    E-Print Network [OSTI]

    Siyang Yang

    2011-11-15T23:59:59.000Z

    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.

  5. Ultrafast Fluorescence Relaxation Spectroscopy of 6,7-Dimethyl-(8-ribityl)-lumazine and Riboflavin, Free and Bound to Antenna Proteins from Bioluminescent Bacteria

    E-Print Network [OSTI]

    van Stokkum, Ivo

    Ultrafast Fluorescence Relaxation Spectroscopy of 6,7-Dimethyl-(8-ribityl)-lumazine and Riboflavin-(8-ribityl)-lumazine (lumazine) and riboflavin in an aqueous buffer and both ligands when

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

    ScienceCinema (OSTI)

    Li, Weizhong [San Diego Supercomputer Center

    2013-01-22T23:59:59.000Z

    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.

  7. Structure and dynamics of electrical double layers in organic electrolytes

    SciTech Connect (OSTI)

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

    2010-01-01T23:59:59.000Z

    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

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

    SciTech Connect (OSTI)

    Miller III, Thomas F.

    2008-08-04T23:59:59.000Z

    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}.

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

    SciTech Connect (OSTI)

    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

    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.

  10. Ultrafast high strain rate acoustic wave measurements at high static pressure in a diamond anvil cell

    SciTech Connect (OSTI)

    Armstrong, M; Crowhurst, J; Reed, E; Zaug, J

    2008-02-04T23:59:59.000Z

    We have used sub-picosecond laser pulses to launch ultra-high strain rate ({approx} 10{sup 9} s{sup -1}) nonlinear acoustic waves into a 4:1 methanol-ethanol pressure medium which has been precompressed in a standard diamond anvil cell. Using ultrafast interferometry, we have characterized acoustic wave propagation into the pressure medium at static compression up to 24 GPa. We find that the velocity is dependent on the incident laser fluence, demonstrating a nonlinear acoustic response which may result in shock wave behavior. We compare our results with low strain, low strain-rate acoustic data. This technique provides controlled access to regions of thermodynamic phase space that are otherwise difficult to obtain.

  11. Efficient Photoionization-Loading of Trapped Cadmium Ions with Ultrafast Pulses

    E-Print Network [OSTI]

    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

    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.

  12. Four-level atomic interferometer driven by shaped ultrafast laser pulses

    SciTech Connect (OSTI)

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

    2010-08-15T23:59:59.000Z

    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.

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

    SciTech Connect (OSTI)

    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

    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.

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

    E-Print Network [OSTI]

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

    2015-01-01T23:59:59.000Z

    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...

  15. An ultrafast angle-resolved photoemission apparatus for measuring complex materials

    SciTech Connect (OSTI)

    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

    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.

  16. Phonon-Assisted Ultrafast Charge Separation in a Realistic PCBM Aggregate

    E-Print Network [OSTI]

    Samuel L. Smith; Alex W. Chin

    2014-06-25T23:59:59.000Z

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

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

    SciTech Connect (OSTI)

    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

    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.

  18. Ultra-fast heralded single photon source based on telecom technology

    E-Print Network [OSTI]

    Lutfi Arif Ngah; Olivier Alibart; Laurent Labonté; Virginia D'Auria; Sébastien Tanzilli

    2014-12-17T23:59:59.000Z

    The realization of an ultra-fast source of heralded single photons emitted at the wavelength of 1540 nm is reported. The presented strategy is based on state-of-the-art telecom technology, combined with off-the-shelf fiber components and waveguide non-linear stages pumped by a 10 GHz repetition rate laser. The single photons are heralded at a rate as high as 2.1 MHz with a heralding efficiency of 42%. Single photon character of the source is inferred by measuring the second-order autocorrelation function. For the highest heralding rate, a value as low as 0.023 is found. This not only proves negligible multi-photon contributions but also represents the best measured value reported to date for heralding rates in the MHz regime. These prime performances, associated with a device-like configuration, are key ingredients for both fast and secure quantum communication protocols.

  19. Ultra-fast photoluminescence as a diagnostic for laser damage initiation

    SciTech Connect (OSTI)

    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

    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.

  20. (4R,4aR,6S,7S,7aS)-6-Hydroxy-7-hy- droxymethyl-4-methylperhydrocyclo- penta[c]pyran-1-one chloroform solvate from Valeriana laxiflora

    E-Print Network [OSTI]

    Khera, Smriti; Carducci, Michael D.; Gu, Jian-Qiao; Timmermann, Barbara N.

    2004-01-01T23:59:59.000Z

    The structure of an iridolactone isolated from Valeriana laxiflora was established as (4R,4aR,6S,7S,7aS)-6-hydroxy-7-hydroxy­methyl-4-methyl­per­hydro­cyclo­penta­[c]­pyran-1-one chloro­form solvate, C10H16O4·CHCl3. The two rings are cis...

  1. Study of the subpicosecond rotational molecular dynamics in liquids

    SciTech Connect (OSTI)

    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

    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)

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

    E-Print Network [OSTI]

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

    2011-06-29T23:59:59.000Z

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

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

    E-Print Network [OSTI]

    Parvendra Kumar; Amarendra K. Sarma

    2012-11-16T23:59:59.000Z

    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.

  4. 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

  5. Proceedings of "Optical Probes of Dynamics in Complex Environments"

    SciTech Connect (OSTI)

    Sension, R; Tokmakoff, A

    2008-04-01T23:59:59.000Z

    This document contains the proceedings from the symposium on Optical Probes of Dynamics in Complex Environments, which organized as part of the 235th National Meeting of the American Chemical Society in New Orleans, LA from April 6 to 10, 2008. The study of molecular dynamics in chemical reaction and biological processes using time ���������������resolved spectroscopy plays an important role in our understanding of energy conversion, storage, and utilization problems. Fundamental studies of chemical reactivity, molecular rearrangements, and charge transport are broadly supported by the DOE Office of Science because of their role in the development of alternative energy sources, the understanding of biological energy conversion processes, the efficient utilization of existing energy resources, and the mitigation of reactive intermediates in radiation chemistry. In addition, time resolved spectroscopy is central to all of DOEs grand challenges for fundamental energy science. This symposium brought together leaders in the field of ultrafast spectroscopy, including experimentalists, theoretical chemists, and simulators, to discuss the most recent scientific and technological advances. DOE support for this conference was used to help young US and international scientists travel to the meeting. The latest technology in ultrafast infrared, optical, and xray spectroscopy and the scientific advances that these methods enable were covered. Particular emphasis was placed on new experimental methods used to probe molecular dynamics in liquids, solids, interfaces, nanostructured materials, and biomolecules.

  6. Quantum Chemical Analysis of the Excited State Dynamics of Hydrated Electrons

    E-Print Network [OSTI]

    P. O. J. Scherer; Sighart F. Fischer

    2006-02-01T23:59:59.000Z

    Quantum calculations are performed for an anion water cluster representing the first hydration shell of the solvated electron in solution. The absorption spectra from the ground state, the instant excited states and the relaxed excited states are calculated including CI-SD interactions. Analytic expressions for the nonadiabatic relaxation are presented. It is shown that the 50fs dynamics recently observed after s->p excitation is best accounted for if it is identified with the internal conversion, preceded by an adiabatic relaxation within the excited p state. In addition, transient absorptions found in the infrared are qualitatively reproduced by these calculations .

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

    SciTech Connect (OSTI)

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

    2011-06-27T23:59:59.000Z

    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.

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

    SciTech Connect (OSTI)

    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

    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.

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

    E-Print Network [OSTI]

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

    2008-06-25T23:59:59.000Z

    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.

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

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

    Dai, Yang [Shanghai Inst. of Space Power Sources, Shanghai (China); Zhu, Yimei [Brookhaven National Lab. (BNL), Upton, NY (United States); Cai, Sendan [Shanghai Inst. of Space Power Sources, Shanghai (China); Wu, Lijun [Brookhaven National Lab. (BNL), Upton, NY (United States); Yang, Weijing [Shanghai Inst. of Space Power Sources, Shanghai (China); Xie, Jingying [Shanghai Inst. of Space Power Sources, Shanghai (China); Shanghai Engineering Center for Power and Energy Storage Systems, Shanghai (China); Wen, Wen [BL14B1 Shanghai Synchrotron Radiation Facility, Shanghai (China); Zheng, Jin-Cheng [Xiamen Univ., Xiamen (China); Zheng, Yi [Shanghai Inst. of Space Power Sources, Shanghai (China)

    2014-01-01T23:59:59.000Z

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

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

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

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

    2014-01-01T23:59:59.000Z

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

  12. Ultrafast Manipulation of a Double Quantum Dot via Lyapunov Control Method

    E-Print Network [OSTI]

    Shuang Cong; Ming-yong Gao; Long-zhen Hu; Guo-ping Guo; Gang Cao; Guang-can Guo

    2014-01-12T23:59:59.000Z

    For a double quantum dot (DQD) system, here we propose alternative ultrafast manipulate approach: Lyapunov control method, to transfer the state from R to L on the picosecond scale, orders of magnitude faster and transfer probability higher than the previously measured electrically controlled charge- or spin-based quits. The control laws are composed of two-direction components, one is used to eliminate the dissipation in the system, another is used to transfer the state. The control theory's stability ensures the system can be transferred to the target state in high probability, and the coefficients in control laws leads very fast convergence. The role of eliminating the dissipation plays the suppression of decoherence effect. Numerical simulation results show that under the realistic implementation conditions, the transfer probability and fidelity can be increased up to 98.79% and 98.97%, respectively. This is the first result directly applicable to a DQD system's state transferring using the Lyapunov control method. We also give specific experimental realization scheme.

  13. On the presence of ultra-fast outflows in the WAX sample of Seyfert galaxies

    E-Print Network [OSTI]

    Tombesi, Francesco

    2014-01-01T23:59:59.000Z

    The study of winds in active galactic nuclei (AGN) is of utmost importance as they may provide the long sought-after link between the central black hole and the host galaxy, establishing the AGN feedback. Recently, Laha et al. (2014) reported the X-ray analysis of a sample of 26 Seyferts observed with XMM-Newton, which are part of the so-called warm absorbers in X-rays (WAX) sample. They claim the non-detection of Fe K absorbers indicative of ultra-fast outflows (UFOs) in four observations previously analyzed by Tombesi et al. (2010). They mainly impute the Tombesi et al. detections to an improper modeling of the underlying continuum in the E=4-10 keV band. We therefore re-address here the robustness of these detections and we find that the main reason for the claimed non-detections is likely due to their use of single events only spectra, which reduces the total counts by 40%. Performing a re-analysis of the data in the whole E=0.3-10 keV energy band using their models and spectra including also double event...

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

    E-Print Network [OSTI]

    Grimm, Simon L

    2015-01-01T23:59:59.000Z

    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...

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

    E-Print Network [OSTI]

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

    2013-01-01T23:59:59.000Z

    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...

  16. Can Natural Sunlight Induce Coherent Exciton Dynamics?

    E-Print Network [OSTI]

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

    2014-08-21T23:59:59.000Z

    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.

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

    SciTech Connect (OSTI)

    Heather Marie Netzloff

    2004-12-19T23:59:59.000Z

    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.

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

    E-Print Network [OSTI]

    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

    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...

  19. 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)

    Ghadar, Yasaman; Clark, Aurora E.

    2012-02-02T23:59:59.000Z

    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).

  20. Adding quantum effects to the semi-classical molecular dynamics simulations

    E-Print Network [OSTI]

    Yang, Siyang

    2011-01-01T23:59:59.000Z

    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 trajecto...

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

    SciTech Connect (OSTI)

    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

    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.

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

    E-Print Network [OSTI]

    Parvendra Kumar; Amarendra K. Sarma

    2013-03-01T23:59:59.000Z

    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.

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

    E-Print Network [OSTI]

    Amarendra K. Sarma; Parvendra Kumar

    2011-11-17T23:59:59.000Z

    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.

  4. Spatiotemporal Imaging of Ultrafast Molecular Motion: Collapse and Revival of the D{sub 2}{sup +} Nuclear Wave Packet

    SciTech Connect (OSTI)

    Ergler, Th.; Rudenko, A.; Zrost, K.; Schroeter, C. D.; Moshammer, R.; Ullrich, J. [Max-Planck-Institut fuer Kernphysik, D-69029 Heidelberg (Germany); Feuerstein, B. [Max-Planck-Institut fuer Kernphysik, D-69029 Heidelberg (Germany); Physikalisches Institut, Universitaet Heidelberg, 69120 Heidelberg (Germany)

    2006-11-10T23:59:59.000Z

    We report on a real-time imaging of the ultrafast D{sub 2}{sup +} rovibrational nuclear wave-packet motion performed using a combination of a pump-probe setup with 7 fs laser pulses and a 'reaction-microscope' spectrometer. We observe fast dephasing (collapse) of the vibrational wave packet and its subsequent revival and prove rotational excitation in ultrashort laser pulses. Channel-selective Fourier analysis of the wave packet's long-term ({approx}3000 fs) evolution allows us to resolve its individual constituents, revealing unique information on the mechanisms of strong-field ionization and dissociation.

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

    SciTech Connect (OSTI)

    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

    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.

  6. Large-signal dynamics of an ultrafast semiconductor laser at digital modulation rates approaching 10 Gbit/s

    SciTech Connect (OSTI)

    Lau, K.Y.; Yariv, A.

    1985-07-15T23:59:59.000Z

    High-fidelity pseudorandom digital modulation at 8.2 Gbit/s of an ultrahigh speed semiconductor laser is demonstrated. Studies using simple but representative pulse patterns at 10 Gbit/s give insights into the maximum digital modulation rate attainable from a given laser, as well as relations between large-signal digital performance and small-signal analog response.

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

    E-Print Network [OSTI]

    Turro, Claudia

    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

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

    E-Print Network [OSTI]

    Liu, Shilin

    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

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

    E-Print Network [OSTI]

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

  10. 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]

    Cao, Jianming

    , 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

  11. Single-pulse ultrafast-laser machining of high aspect nano-holes at the surface of SiO2

    E-Print Network [OSTI]

    Davis, Lloyd M.

    (2005). 6. T. N. Kim, K. Campbell, A. Groisman, D. Kleinfeld, and C. B. Schaffer, "Femtosecond laser-drilled, and D. Low, "Precision glass machining, drilling and profile cutting by short pulse lasers," Thin SolidSingle-pulse ultrafast-laser machining of high aspect nano-holes at the surface of SiO2 Yelena V

  12. 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]

    Freericks, Jim

    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

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

    E-Print Network [OSTI]

    Yangjie Liu; L. K. Ang

    2014-08-21T23:59:59.000Z

    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.

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

    SciTech Connect (OSTI)

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

    2008-02-07T23:59:59.000Z

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

  15. Solvation free energy calculations using continuum dielectric model for the solvent and gradient-corrected density functional theory for the solute

    SciTech Connect (OSTI)

    Tawa, G.J.; Martin, R.L.; Pratt, L.R.; Russo, T.V. [Los Alamos National Lab., NM (United States)] [Los Alamos National Lab., NM (United States)

    1996-02-01T23:59:59.000Z

    Electrostatic solvation free energies are calculated using a self consistent reaction field (SCRF) procedure that combines a continuum dielectric model of the solvent with both Hartree-Fock (HF) and density functional theory (DFT) for the solute. Several molecules are studied in aqueous solution. They comprise three groups: nonpolar neutral, polar neutral, and ionic. The calculated values of {Delta}G{sup e1} are sensitive to the atomic radii used to define the solute molecular surface, particularly to the value of the hydrogen radius. However, the values of {Delta}G{sup e1} exhibit reasonable correlation with experiment when a previously determined, physically motivated set of atomic radii were used to define the van der Waals surface of the solute. The standard deviation between theory and experiment is 2.51 kcal/mol for HF and 2.21 kcal/mol for DFT for the 14 molecules examined. The errors with HF or DFT are similar. The relative difference between the calculated values of {Delta}G{sup e1} and experiment is largest for nonpolar neutral molecules, intermediate for polar neutral molecules, and smallest for ions. This is consistent with the expected relative importance of nonelectrostatic contributions to the free energy that are omitted in the model. 92 refs., 4 figs., 6 tabs.

  16. Structure and dynamics of aqueous solution of uranyl ions

    SciTech Connect (OSTI)

    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

    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.

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

    SciTech Connect (OSTI)

    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

    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.

  18. Accurate static and dynamic properties of liquid electrolytes...

    Office of Scientific and Technical Information (OSTI)

    LiPF6 at experimental concentrations to build solvation models which explain available neutron scattering and nuclear magnetic resonance (NMR) results and to compute Li-ion...

  19. Sodium Chloride interaction with solvated and crystalline cellulose : sodium ion affects the tetramer and fibril in aqueous solution

    E-Print Network [OSTI]

    Bellesia, Giovanni

    2013-01-01T23:59:59.000Z

    Inorganic salts are a natural component of biomass which have a significant effect on the product yields from a variety of biomass conversion processes. Understanding their effect on biomass at the microscopic level can help discover their mechanistic role. We present a study of the effect of aqueous sodium chloride (NaCl) on the largest component of biomass, cellulose, focused on the thermodynamic and structural effect of a sodium ion on the cellulose tetramer, and fibril. Replica exchange molecular dynamics simulations of a cellulose tetramer reveal a number of preferred cellulose-Na contacts and bridging positions. Large scale MD simulations on a model cellulose fibril find that Na+ perturbs the hydroxymethyl rotational state population and consequently disrupts the "native" hydrogen bonding network.

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

    SciTech Connect (OSTI)

    Cavalcante, Ary de Oliveira, E-mail: arycavalcante@ufam.edu.br [Institute of Chemistry, University of Campinas – UNICAMP, Cx. P. 6154, Campinas, SP 13084-862 (Brazil); Departamento de Química, Universidade Federal do Amazonas, Av. Rodrigo Octávio, 6200, Coroado, Manaus, AM (Brazil); Ribeiro, Mauro C. C. [Laboratório de Espectroscopia Molecular, Instituto de Química, Universidade de São Paulo, São Paulo, SP C.P. 26077, 05513 970 São Paulo, SP (Brazil)] [Laboratório de Espectroscopia Molecular, Instituto de Química, Universidade de São Paulo, São Paulo, SP C.P. 26077, 05513 970 São Paulo, SP (Brazil); Skaf, Munir S. [Institute of Chemistry, University of Campinas – UNICAMP, Cx. P. 6154, Campinas, SP 13084-862 (Brazil)] [Institute of Chemistry, University of Campinas – UNICAMP, Cx. P. 6154, Campinas, SP 13084-862 (Brazil)

    2014-04-14T23:59:59.000Z

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