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Sample records for excite luttinger liquid

  1. Excitation energy after a smooth quench in a Luttinger liquid

    SciTech Connect

    Dziarmaga, Jacek; Tylutki, Marek

    2011-12-01

    Low-energy physics of quasi-one-dimensional ultracold atomic gases is often described by a gapless Luttinger liquid (LL). It is nowadays routine to manipulate these systems by changing their parameters in time but, no matter how slow the manipulation is, it must excite a gapless system. We study a smooth change of parameters of the LL (a smooth ''quench'') with a variable quench time and find that the excitation energy decays with an inverse power of the quench time. This universal exponent is -2 at zero temperature and -1 for slow enough quenches at finite temperature. The smooth quench does not excite beyond the range of validity of the low-energy LL description.

  2. Sliding Luttinger Liquids

    NASA Astrophysics Data System (ADS)

    Kane, Charles

    2002-03-01

    The classification of non Fermi liquid phases in two dimensions remains a difficult problem. In this talk we consider an anisotropic system consisting of an array of weakly coupled one dimensional wires, which may be studied using the powerful technique of 1D bosonization. This anisotropic limit may be of relevance to the stripe phases of high temperature superconductors as well as stripes in the quantum Hall effect. For a range of forward scattering interactions the coupling between the wires is shown to be irrelevant, leading to a novel ``smectic metal", or ``sliding Luttinger liquid" (SLL) phase, which is the quantum analog of sliding phases of coupled classical XY models. The anisotropic transport properties of this phase exhibit power law singularities characteristic of the 1D Luttinger liquid. We go on to show that even when the SLL phase is unstable, the SLL fixed point provides a useful starting point for describing other strongly correlated states in 2D. In particular, we show that in a perpendicular magnetic field our approach provides an elegant new formulation of the fractional quantum Hall effect. This theory describes the gap structure, edge states and quasiparticle excitations for the entire hierarchy of the quantum Hall effect, as well novel crystals of Laughlin quasiparticles.

  3. Particle partition entanglement of bosonic Luttinger liquids

    E-print Network

    C. M. Herdman; A. Del Maestro

    2015-02-25

    We consider the R\\'{e}nyi entanglement entropy of bosonic Luttinger liquids under a particle bipartition and demonstrate that the leading order finite-size scaling is logarithmic in the system size with a prefactor equal to the inverse Luttinger parameter. While higher order corrections involve a microscopic length scale, the leading order scaling depends only on this sole dimensionless parameter which characterizes the low energy quantum hydrodynamics. This result contrasts the leading entanglement entropy scaling under a spatial bipartition, for which the coefficient is universal and independent of the Luttinger parameter. Using quantum Monte Carlo calculations, we explicitly confirm the scaling predictions of Luttinger liquid theory for the Lieb-Liniger model of $\\delta$-function interacting bosons in the one dimensional spatial continuum.

  4. Particle partition entanglement of bosonic Luttinger liquids

    NASA Astrophysics Data System (ADS)

    Herdman, C. M.; Del Maestro, A.

    2015-05-01

    We consider the Rényi entanglement entropy of bosonic Tomonaga-Luttinger liquids under a particle bipartition and demonstrate that the leading order finite-size scaling is logarithmic in the system size with a prefactor equal to the inverse Luttinger parameter. While higher-order corrections involve a microscopic length scale, the leading-order scaling depends only on this sole dimensionless parameter which characterizes the low-energy quantum hydrodynamics. This result contrasts the leading entanglement entropy scaling under a spatial bipartition, for which the coefficient is universal and independent of the Luttinger parameter. Using quantum Monte Carlo calculations, we explicitly confirm the scaling predictions of Tomonaga-Luttinger liquid theory for the Lieb-Liniger model of ? -function interacting bosons in the one-dimensional spatial continuum.

  5. Kinetic theory for interacting Luttinger liquids

    NASA Astrophysics Data System (ADS)

    Buchhold, Michael; Diehl, Sebastian

    2015-10-01

    We derive a closed set of equations for the kinetics and non-equilibrium dynamics of interacting Luttinger Liquids with cubic resonant interactions. In the presence of these interactions, the Luttinger phonons become dressed but still well defined quasi-particles, characterized by a life-time much larger then the inverse energy. This enables the separation of forward time dynamics and relative time dynamics into slow and fast dynamics and justifies the so-called Wigner approximation, which can be seen as a "local-time approximation" for the relative dynamics. Applying field theoretical methods in the Keldysh framework, i.e. kinetic and Dyson-Schwinger equations, we derive a closed set of dynamic equations, describing the kinetics of normal and anomalous phonon densities, the phonon self-energy and vertex corrections for a Gaussian non-equilibrium initial state. In the limit of low phonon densities, the results from self-consistent Born approximation are recaptured, including Andreev's scaling solution for the quasi-particle life-time in a thermal state. As an application, we compute the relaxation of an excited state to its thermal equilibrium. While the intermediate time dynamics displays exponentially fast relaxation, the last stages of thermalization are governed by algebraic laws. This can be traced back to the importance of energy and momentum conservation at the longest times, which gives rise to dynamical slow modes.

  6. Fermionic Luttinger liquids from a microscopic perspective

    E-print Network

    Manuel Valiente; Lawrence G. Phillips; Nikolaj T. Zinner; Patrik Ohberg

    2015-05-13

    We consider interacting one-dimensional, spinless Fermi gases, whose low-energy properties are described by Luttinger liquid theory. We perform a systematic, in-depth analysis of the relation between the macroscopic, phenomenological parameters of Luttinger liquid effective field theory, and the microscopic interactions of the Fermi gas. In particular, we begin by explaining how to model effective interactions in one dimension, which we then apply to the main forward scattering channel -- the interbranch collisions -- common to these systems. We renormalise the corresponding interbranch phenomenological constants in favour of scattering phase shifts. Interestingly, our renormalisation procedure shows (i) how Luttinger's model arises in a completely natural way -- and not as a convenient approximation -- from Tomonaga's model, and (ii) the reasons behind the interbranch coupling constant remaining unrenormalised in Luttinger's model. We then consider the so-called intrabranch processes, whose phenomenological coupling constant is known to be fixed by charge conservation, but whose microscopic origin is not well understood. We show that, contrary to general belief and common sense, the intrabranch interactions appearing in Luttinger liquid theory do not correspond to an intrabranch scattering channel, nor an energy shift due to intrabranch interactions, in the microscopic theory. Instead, they are due to interbranch processes. We finally apply our results to a particular example of an exactly solvable model, namely the fermionic dual to the Lieb-Liniger model in the Tonks-Girardeau and super-Tonks-Girardeau regimes.

  7. Low temperature dynamics of nonlinear Luttinger liquids

    NASA Astrophysics Data System (ADS)

    Karrasch, C.; Pereira, R. G.; Sirker, J.

    2015-10-01

    We develop a general nonlinear Luttinger liquid theory to describe the dynamics of one-dimensional quantum critical systems at low temperatures. To demonstrate the predictive power of our theory we compare results for the autocorrelation G(t) in the XXZ chain with numerical density-matrix renormalization group data and obtain excellent agreement. Our calculations provide, in particular, direct evidence that G(t) shows a diffusion-like decay, G(t)? 1/\\sqrt{t}, in sharp contrast to the exponential decay in time predicted by conventional Luttinger liquid theory.

  8. Spin Dimers: from BEC to Luttinger liquids

    NASA Astrophysics Data System (ADS)

    Giamarchi, Thierry

    2011-03-01

    Localized spin systems, and in particular dimer systems, provide a fantastic laboratory to study the interplay between quantum effects and the interaction between excitations. Magnetic field and temperature allow an excellent control on the density of excitations and various very efficient probes such as neutrons and NMR are available. They can thus be used as ``quantum simulators'' to tackle with great success questions that one would normally search in itinerant interacting quantum systems. In particular they have provided excellent realizations of Bose-Einstein condensates [1,2]. This allowed not only to probe the properties of interacting bosons in a variety of dimensions but also to study in a controlled way additional effects such as disorder. If the dimensionality is reduced they also allow to test in a quantitative way Luttinger liquid physics [3,4,5]. I will discuss these various cases, and show that we have now good theoretical tools to make quantitative comparisons with the experiments. Finally, how to go from this low dimensional case where the spins behave essentially as fermions, to the higher dimensional case where they behave as (essentially free) bosons, is a very challenging, and experimentally relevant issue. This work was supported in part by the Swiss SNF under MaNEP and division II.

  9. Measure of equilibration in Luttinger liquids

    NASA Astrophysics Data System (ADS)

    Medvedyeva, Mariya; Kehrein, Stefan

    2015-03-01

    We consider the properties of the Luttinger liquid in the echo protocol (forward evolution in time followed by the backward evolution of slightly perturbed system) and explore the relation of the Loschmidt echo (the overlap of the initial and final wavefunctions) and the measurable properties of the system. We first study the linear Luttinger liquid as an example of an integrable system and find that the momentum distribution function exhibits almost complete recurrence while the Loschmidt echo does not, as the diagonal basis is different during the forward and backward time evolution. For a nonlinear Luttinger liquid the recurrence strength of the momentum distribution function drops as the nonlinearity of the fermion dispersion relation grows. We conclude that there is no simple relation of the Loschmidt echo to the behavior of the observables and that more work is needed to understand how to interpret the echo in the context of experiment. This work was supported through SFB 1073 (project B03) of the Deutsche Forschungsgemeinschaft (DFG).

  10. Electrical and Thermal Transport in Inhomogeneous Luttinger Liquids.

    PubMed

    DeGottardi, Wade; Matveev, K A

    2015-06-12

    We study the transport properties of long quantum wires by generalizing the Luttinger liquid approach to allow for the finite lifetime of the bosonic excitations. Our theory accounts for long-range disorder and strong electron interactions, both of which are common features of experiments with quantum wires. We obtain the electrical and thermal resistances and thermoelectric properties of such quantum wires and find a strong deviation from perfect conductance quantization. We cast our results in terms of the thermal conductivity and bulk viscosity of the electron liquid and give the temperature scale above which the transport can be described by classical hydrodynamics. PMID:26196812

  11. Non-equilibrium Luttinger liquids Alexander D. Mirlin

    E-print Network

    Fominov, Yakov

    Non-equilibrium Luttinger liquids Alexander D. Mirlin Forschungszentrum & Universit¨at Karlsruhe, Rehovot http://www.tkm.uni-karlsruhe.de/mirlin/ #12;Plan · Non-equilibrium Luttinger liquid: Setups · Partial non-equilibrium · Tunneling DOS, zero-bias anomaly (ZBA), dephasing · Energy relaxation · Full non-equilibrium

  12. A brief exposition on Luttinger liquid theory December 6, 2012

    E-print Network

    one direction in the crystal is much larger than any other direction, and so electrons travelling of Fermi liquids in higher dimensions break down in 1-d, hence the need for Luttinger liquid theory through the crystal eectively only travel along that direction. Such crystals are called Bechgaard salts

  13. a Luttinger Liquid Core Inside HELIUM-4 Filled Nanopores

    NASA Astrophysics Data System (ADS)

    Del Maestro, Adrian

    2014-10-01

    As helium-4 is cooled below 2.17 K it undergoes a phase transition to a fundamentally quantum mechanical state of matter known as a superfluid which supports flow without viscosity. This type of dissipationless transport can be observed by forcing helium to travel through a narrow constriction that the normal liquid could not penetrate. Recent experiments have highlighted the feasibility of fabricating smooth pores with nanometer radii, that approach the truly one-dimensional limit where it is believed that a system of bosons (like helium-4) may have startlingly different behavior than in three dimensions. The one-dimensional system is predicted to have a linear hydrodynamic description known as Luttinger liquid (LL) theory, where no type of long range order can be sustained. In the limit where the pore radius is small, LL theory would predict that helium inside the channel behaves as a sort of quasi-supersolid with all correlations decaying as power-law functions of distance at zero temperature. We have performed large scale quantum Monte Carlo simulations of helium-4 inside nanopores of varying radii at low temperature with realistic helium.helium and helium-pore interactions. The results indicate that helium inside the nanopore forms concentric cylindrical shells surrounding a core that can be described via LL theory and provides insights into the exciting possibility of the experimental detection of this intriguing low-dimensional state of matter.

  14. a Luttinger Liquid Core Inside HELIUM-4 Filled Nanopores

    NASA Astrophysics Data System (ADS)

    Del Maestro, Adrian

    2012-09-01

    As helium-4 is cooled below 2.17 K it undergoes a phase transition to a fundamentally quantum mechanical state of matter known as a superfluid which supports flow without viscosity. This type of dissipationless transport can be observed by forcing helium to travel through a narrow constriction that the normal liquid could not penetrate. Recent experiments have highlighted the feasibility of fabricating smooth pores with nanometer radii, that approach the truly one-dimensional limit where it is believed that a system of bosons (like helium-4) may have startlingly different behavior than in three dimensions. The one-dimensional system is predicted to have a linear hydrodynamic description known as Luttinger liquid (LL) theory, where no type of long range order can be sustained. In the limit where the pore radius is small, LL theory would predict that helium inside the channel behaves as a sort of quasi-supersolid with all correlations decaying as power-law functions of distance at zero temperature. We have performed large scale quantum Monte Carlo simulations of helium-4 inside nanopores of varying radii at low temperature with realistic helium-helium and helium-pore interactions. The results indicate that helium inside the nanopore forms concentric cylindrical shells surrounding a core that can be described via LL theory and provides insights into the exciting possibility of the experimental detection of this intriguing low-dimensional state of matter.

  15. Luttinger Liquid in Non-equilibrium Steady State

    E-print Network

    Mihail Mintchev; Paul Sorba

    2012-10-19

    We propose and investigate an exactly solvable model of non-equilibrium Luttinger liquid on a star graph, modeling a multi-terminal quantum wire junction. The boundary condition at the junction is fixed by an orthogonal matrix S, which describes the splitting of the electric current among the leads. The system is driven away from equilibrium by connecting the leads to heat baths at different temperatures and chemical potentials. The associated non-equilibrium steady state depends on S and is explicitly constructed. In this context we develop a non-equilibrium bosonization procedure and compute some basic correlation functions. Luttinger liquids with general anyon statistics are considered. The relative momentum distribution away from equilibrium turns out to be the convolution of equilibrium anyon distributions at different temperatures. Both the charge and heat transport are studied. The exact current-current correlation function is derived and the zero-frequency noise power is determined.

  16. Effet Hall quantique, liquides de Luttinger et charges fractionnaires

    NASA Astrophysics Data System (ADS)

    Roche, Patrice; Rodriguez, V.; Glattli, D. Christian

    We review some basic properties of the Fractional Quantum Hall Effect and particularly address the physics of the edge states. The chiral Luttinger liquid properties of the edges are discussed and probed experimentally using transport measurements. Shot noise measurements, which allow determination of the quasiparticle charge are also discussed. To cite this article: P. Roche et al., C. R. Physique 3 (2002) 717-732.

  17. Plasmon decay and thermal transport from spin-charge coupling in generic Luttinger liquids.

    PubMed

    Levchenko, Alex

    2014-11-01

    We discuss the violation of spin-charge separation in generic nonlinear Luttinger liquids and investigate its effect on the relaxation and thermal transport of genuine spin-1/2 electron liquids in ballistic quantum wires. We identify basic scattering processes compatible with the symmetry of the problem and conservation laws that lead to the decay of plasmons into the spin modes. We derive a closed set of coupled kinetic equations for the spin-charge excitations and solve the problem of thermal conductance of interacting electrons for an arbitrary relation between the quantum wire length and spin-charge thermalization length. PMID:25415912

  18. Nonequilibrium transport of helical Luttinger liquids through a quantum dot

    NASA Astrophysics Data System (ADS)

    Chao, Sung-Po; Silotri, Salman A.; Chung, Chung-Hou

    2013-08-01

    We study a steady-state nonequilibrium transport between two interacting helical edge states of a two-dimensional topological insulator, described by helical Luttinger liquids, through a quantum dot. For a noninteracting dot, the current is obtained analytically by including the self-energy correction to the dot's Green function. For an interacting dot, we use the equation-of-motion method to study the influence of weak on-site Coulomb interaction on the transport. We find the metal-to-insulator quantum phase transition for attractive or repulsive interactions in the leads when the magnitude of the interaction strength characterized by a charge sector Luttinger parameter K goes beyond a critical value. The critical Luttinger parameter Kcr depends on the hopping strengths between the dot and the leads, as well as the energy level of the dot with respect to the Fermi levels of the leads, ranging from the weak-interaction regime for the dot level off-resonance to the strong-interaction regime for the dot in resonance with the equilibrium Fermi level. Near the transition, there are various singular behaviors of current noise, dot density of state, and the decoherence rate (inverse of lifetime) of the dot, which are briefly discussed.

  19. One-Dimensional Fermions with neither Luttinger-Liquid nor Fermi-Liquid Behavior

    NASA Astrophysics Data System (ADS)

    Rozhkov, A. V.

    2014-03-01

    It is well known that, generically, one-dimensional interacting fermions cannot be described in terms of a Fermi liquid. Instead, they present a different phenomenology, that of a Tomonaga-Luttinger liquid: the Landau quasiparticles are ill defined, and the fermion occupation number is continuous at the Fermi energy. We demonstrate that suitable fine tuning of the interaction between fermions can stabilize a peculiar state of one-dimensional matter, which is dissimilar to both Tomonaga-Luttinger and Fermi liquids. We propose to call this state a quasi-Fermi liquid. Technically speaking, such a liquid exists only when the fermion interaction is irrelevant (in the renormalization group sense). The quasi-Fermi liquid exhibits the properties of both a Tomonaga-Luttinger liquid and a Fermi liquid. Similar to a Tomonaga-Luttinger liquid, no finite-momentum quasiparticles are supported by the quasi-Fermi liquid; on the other hand, its fermion occupation number demonstrates a finite discontinuity at the Fermi energy, which is a hallmark feature of a Fermi liquid. A possible realization of the quasi-Fermi liquid with the help of cold atoms in an optical trap is discussed.

  20. Measuring the Luttinger liquid parameter with shot noise

    NASA Astrophysics Data System (ADS)

    Kühne, J. K.; Protopopov, I. V.; Oreg, Y.; Mirlin, A. D.

    2015-11-01

    We explore the low-frequency noise of interacting electrons in a one-dimensional structure (quantum wire or interaction-coupled edge states) with counterpropagating modes, assuming a single channel in each direction. The system is driven out of equilibrium by a quantum point contact (QPC) with an applied voltage, which induces a double-step energy distribution of incoming electrons on one side of the device. A second QPC serves to explore the statistics of outgoing electrons. We show that measurement of a low-frequency noise in such a setup allows one to extract the Luttinger liquid constant K which is the key parameter characterizing an interacting 1D system. We evaluate the dependence of the zero-frequency noise on K and on parameters of both QPCs (transparencies and voltages).

  1. Anomalous chiral Luttinger liquid behavior of diluted fractionally charged quasiparticles

    NASA Astrophysics Data System (ADS)

    Chung, Y. C.; Heiblum, M.; Oreg, Y.; Umansky, V.; Mahalu, D.

    2003-05-01

    Fractionally charged quasiparticles in edge states, are expected to condense to a chiral Luttinger liquid (CLL). We studied their condensation by measuring the conductance and shot noise due to an artificial backscatterer embedded in their path. At sufficiently low-temperatures backscattering events were found to be strongly correlated, producing a highly nonlinear current-voltage characteristic and a nonclassical shot noise—both are expected in a CLL. When, however, the impinging beam of quasiparticles was made dilute, either artificially via an additional weak backscatterer or by increasing the temperature, the resultant outgoing noise was classical, indicating the scattering of independent quasiparticles. Here, we study in some detail this surprising crossover from correlated particle behavior to an independent behavior, as a function of beam dilution and temperature.

  2. Luttinger Liquid, Singular Interaction and Quantum Criticality in Cuprate Materials

    NASA Astrophysics Data System (ADS)

    di Castro, C.; Caprara, S.

    2014-10-01

    With particular reference to the role of the renormalization group (RG) approach and Ward identities (WI's), we start by recalling some old features of the one-dimensional Luttinger liquid as the prototype of non-Fermi-liquid behavior. Its dimensional crossover to the Landau normal Fermi liquid implies that a non-Fermi liquid, as, e.g., the normal phase of the cuprate high temperature superconductors, can be maintained in d > 1 only in the presence of a sufficiently singular effective interaction among the charge carriers. This is the case when, nearby an instability, the interaction is mediated by critical fluctuations. We are then led to introduce the specific case of superconductivity in cuprates as an example of avoided quantum criticality. We will disentangle the fluctuations which act as mediators of singular electron-electron interaction, enlightening the possible order competing with superconductivity and a mechanism for the non-Fermi-liquid behavior of the metallic phase. This paper is not meant to be a comprehensive review. Many important contributions will not be considered. We will also avoid using extensive technicalities and making full calculations for which we refer to the original papers and to the many good available reviews. We will here only follow one line of reasoning which guided our research activity in this field.

  3. Narrow-gap Luttinger liquid in carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Levitov, Leonid

    2008-03-01

    Single-walled carbon nanotubes are the thinnest and the cleanest among the currently available nanoscale quantum wires. Transport properties of nanotubes depend on the presence of a gap in electron spectrum, defining two main nanotube types, metallic and semiconducting. Semiconducting tubes attract interest in particular because of the sensitivity of their properties to external fields and doping. Among semiconducting tubes there is an interesting class of narrow-gap tubes, or so-called chiral metallic tubes, which exhibit a narrow semiconducting gap arising due to curvature [1]. The Luttinger liquid effects, which are strong in all nanotubes, are particularly interesting in the narrow-gap tubes. Interaction strongly affects the energy gap, reinforcing it and making it sensitive to the long-wavelength charge mode dynamics [2]. We discuss new types of charge carriers possible in the gapped states and their relation to recent experimental work [3]. [1] C.L. Kane and E.J. Mele, Phys. Rev. Lett. 78, 1932 (1997) [2] L. S. Levitov, A. M. Tsvelik, Phys. Rev. Lett. 90, 016401 (2003) [3] V. V. Deshpande, M. Bockrath, arXiv:0710.0683

  4. Transient dynamics of spin-polarized injection in helical Luttinger liquids

    NASA Astrophysics Data System (ADS)

    Calzona, A.; Carrega, M.; Dolcetto, G.; Sassetti, M.

    2015-11-01

    We analyze the time evolution of spin-polarized electron wave packets injected into the edge states of a two-dimensional topological insulator. In the presence of electron interactions, the system is described as a helical Luttinger liquid and injected electrons fractionalize. However, because of the presence of metallic detectors, no evidences of fractionalization are encoded in dc measurements, and in this regime the system does not show deviations from its non-interacting behavior. Nevertheless, we show that the helical Luttinger liquid nature emerges in the transient dynamics, where signatures of charge/spin fractionalization can be clearly identified.

  5. Observation of a Helical Luttinger Liquid in InAs/GaSb Quantum Spin Hall Edges.

    PubMed

    Li, Tingxin; Wang, Pengjie; Fu, Hailong; Du, Lingjie; Schreiber, Kate A; Mu, Xiaoyang; Liu, Xiaoxue; Sullivan, Gerard; Csáthy, Gábor A; Lin, Xi; Du, Rui-Rui

    2015-09-25

    We report on the observation of a helical Luttinger liquid in the edge of an InAs/GaSb quantum spin Hall insulator, which shows characteristic suppression of conductance at low temperature and low bias voltage. Moreover, the conductance shows power-law behavior as a function of temperature and bias voltage. The results underscore the strong electron-electron interaction effect in transport of InAs/GaSb edge states. Because of the fact that the Fermi velocity of the edge modes is controlled by gates, the Luttinger parameter can be fine tuned. Realization of a tunable Luttinger liquid offers a one-dimensional model system for future studies of predicted correlation effects. PMID:26451576

  6. One-Dimensional Quantum Liquids with Power-Law Interactions: The Luttinger Staircase

    SciTech Connect

    Dalmonte, M.; Pupillo, G.; Zoller, P.

    2010-10-01

    We study one-dimensional fermionic and bosonic gases with repulsive power-law interactions 1/|x|{sup {beta}}, with {beta}>1, in the framework of Tomonaga-Luttinger liquid (TLL) theory. We obtain an accurate analytical expression linking the TLL parameter to the microscopic Hamiltonian, for arbitrary {beta} and strength of the interactions. In the presence of a small periodic potential, power-law interactions make the TLL unstable towards the formation of a cascade of lattice solids with fractional filling, a 'Luttinger staircase'. Several of these quantum phases and phase transitions are realized with ground state polar molecules and weakly bound magnetic Feshbach molecules.

  7. Absence of Orthogonality Catastrophe after a Spatially Inhomogeneous Interaction Quench in Luttinger Liquids

    NASA Astrophysics Data System (ADS)

    Dóra, Balázs; Pollmann, Frank

    2015-08-01

    We investigate the Loschmidt echo, the overlap of the initial and final wave functions of Luttinger liquids after a spatially inhomogeneous interaction quench. In studying the Luttinger model, we obtain an analytic solution of the bosonic Bogoliubov-de Gennes equations after quenching the interactions within a finite spatial region. As opposed to the power-law temporal decay following a potential quench, the interaction quench in the Luttinger model leads to a finite, hardly time-dependent overlap; therefore, no orthogonality catastrophe occurs. The steady state value of the Loschmidt echo after a sudden inhomogeneous quench is the square of the respective adiabatic overlaps. Our results are checked and validated numerically on the X X Z Heisenberg chain.

  8. Absence of Orthogonality Catastrophe after a Spatially Inhomogeneous Interaction Quench in Luttinger Liquids.

    PubMed

    Dóra, Balázs; Pollmann, Frank

    2015-08-28

    We investigate the Loschmidt echo, the overlap of the initial and final wave functions of Luttinger liquids after a spatially inhomogeneous interaction quench. In studying the Luttinger model, we obtain an analytic solution of the bosonic Bogoliubov-de Gennes equations after quenching the interactions within a finite spatial region. As opposed to the power-law temporal decay following a potential quench, the interaction quench in the Luttinger model leads to a finite, hardly time-dependent overlap; therefore, no orthogonality catastrophe occurs. The steady state value of the Loschmidt echo after a sudden inhomogeneous quench is the square of the respective adiabatic overlaps. Our results are checked and validated numerically on the XXZ Heisenberg chain. PMID:26371667

  9. Duality of weak and strong scatterer in a Luttinger liquid coupled to massless bosons.

    PubMed

    Yurkevich, Igor V; Galda, Alexey; Yevtushenko, Oleg M; Lerner, Igor V

    2013-03-29

    We study electronic transport in a Luttinger liquid with an embedded impurity, which is either a weak scatterer (WS) or a weak link (WL), when interacting electrons are coupled to one-dimensional massless bosons (e.g., acoustic phonons). We find that the duality relation, ?WS?WL=1, between scaling dimensions of the electron backscattering in the WS and WL limits, established for the standard Luttinger liquid, holds in the presence of the additional coupling for an arbitrary fixed strength of boson scattering from the impurity. This means that at low temperatures such a system remains either an ideal insulator or an ideal metal, regardless of the scattering strength. On the other hand, when fermion and boson scattering from the impurity are correlated, the system has a rich phase diagram that includes a metal-insulator transition at some intermediate values of the scattering. PMID:23581351

  10. Intermediate fixed point in a Luttinger liquid with elastic and dissipative backscattering

    NASA Astrophysics Data System (ADS)

    Altland, Alexander; Gefen, Yuval; Rosenow, Bernd

    2015-08-01

    In a recent work [A. Altland, Y. Gefen, and B. Rosenow, Phys. Rev. Lett. 108, 136401 (2012), 10.1103/PhysRevLett.108.136401], we have addressed the problem of a Luttinger liquid with a scatterer that allows for both coherent and incoherent scattering channels. We have found that the physics associated with this model is qualitatively different from the elastic impurity setup analyzed by Kane and Fisher, and from the inelastic scattering scenario studied by Furusaki and Matveev, thus proposing a paradigmatic picture of Luttinger liquid with an impurity. Here we present an extensive study of the renormalization group flows for this problem, the fixed point landscape, and scaling near those fixed points. Our analysis is nonperturbative in the elastic tunneling amplitudes, employing an instanton calculation in one or two of the available elastic tunneling channels. Our analysis accounts for nontrivial Klein factors, which represent anyonic or fermionic statistics. These Klein factors need to be taken into account due to the fact that higher-order tunneling processes take place. In particular, we find a stable fixed point, where an incoming current is split 1/2 -1/2 between a forward and a backward scattered beams. This intermediate fixed point, between complete backscattering and full forward scattering, is stable for the Luttinger parameter g <1 .

  11. Quantum impurity in a Tomonaga-Luttinger liquid: Continuous-time quantum Monte Carlo approach

    NASA Astrophysics Data System (ADS)

    Hattori, K.; Rosch, A.

    2014-09-01

    We develop a continuous-time quantum Monte Carlo (CTQMC) method for quantum impurities coupled to interacting quantum wires described by a Tomonaga-Luttinger liquid. The method is negative-sign free for any values of the Tomonaga-Luttinger parameter, which is rigorously proved, and, thus, efficient low-temperature calculations are possible. Duality between electrons and bosons in one-dimensional systems allows us to construct a simple formula for the CTQMC algorithm in these systems. We show that the CTQMC for Tomonaga-Luttinger liquids can be implemented with only minor modifications of previous CTQMC codes developed for impurities coupled to noninteracting fermions. We apply this method to the Kane-Fisher model of a potential scatterer in a spin-less quantum wire and to a single spin coupled with the edge state of a two-dimensional topological insulator assuming an anisotropic XXZ coupling. Various dynamical response functions such as the electron Green's function and spin-spin correlation functions are calculated numerically and their scaling properties are discussed.

  12. Particle-Hole Symmetric Luttinger Liquids in a Quantum Hall Circuit

    NASA Astrophysics Data System (ADS)

    Roddaro, Stefano; Pellegrini, Vittorio; Beltram, Fabio; Pfeiffer, Loren N.; West, Ken W.

    2005-10-01

    We report current transmission data through a split-gate constriction fabricated onto a two-dimensional electron system in the integer quantum Hall (QH) regime. Split-gate biasing drives interedge backscattering and is shown to lead to suppressed or enhanced transmission, in marked contrast to the expected linear Fermi-liquid behavior. This evolution is described in terms of particle-hole symmetry and allows us to conclude that an unexpected class of gate-controlled particle-hole-symmetric chiral Luttinger liquids (CLLs) can exist at the edges of our QH circuit. These results highlight the role of particle-hole symmetry on the properties of CLL edge states.

  13. Determination of Tomonaga-Luttinger parameters for a two-component liquid

    NASA Astrophysics Data System (ADS)

    Sule, Olabode M.; Changlani, Hitesh J.; Maruyama, Isao; Ryu, Shinsei

    2015-08-01

    We provide evidence for the mapping of critical spin-1 chains, in particular the SU (3 ) symmetric bilinear-biquadratic model with additional interactions, to free boson theories using exact diagonalization and the density-matrix renormalization-group algorithm. Using the correspondence with a conformal field theory with central charge c =2 , we determine the analytic formulas for the scaling dimensions in terms of four Tomonaga-Luttinger liquid parameters. By matching the lowest scaling dimensions, we numerically calculate these field-theoretic parameters and track their evolution as a function of the parameters of the lattice model.

  14. Temperature dependence of the anomalous exponent in Li(0.9)Mo(6)O(17) that reveals Luttinger Liquid behavior

    NASA Astrophysics Data System (ADS)

    Matzdorf, Rene; Novgorodov, Tatjana; Nansseu, Bernard; Waelsch, Michael; He, Jian; Jin, Rongying; Mandrus, David

    2008-03-01

    Scanning tunneling spectroscopy (STS) has been used to study the Luttinger-liquid behavior of the purple bronze Li(0.9)Mo(6)O(17) in the temperature range 5K < T < 300K. In the entire temperature range the suppression of density of states at the Fermi-energy could be fitted very good by a model describing the tunneling into a Luttinger liquid at ambient temperature. The power-law exponent extracted from these fits reveals a significant increase above 200K. It changes from ?=0.6 at low temperature to ?=1.0 at room temperature.

  15. Luttinger liquid behaviour of Li0.9Mo6O17 studied by scanning tunnelling microscopy

    NASA Astrophysics Data System (ADS)

    Podlich, T.; Klinke, M.; Nansseu, B.; Waelsch, M.; Bienert, R.; He, J.; Jin, R.; Mandrus, D.; Matzdorf, R.

    2013-01-01

    Scanning tunnelling spectroscopy (STS) was used to study the Luttinger liquid behaviour of the purple bronze Li0.9Mo6O17 in the temperature range 5 K < T < 300 K. In the entire temperature range the suppression of the density of states at the Fermi energy can be fitted very well by a model describing the tunnelling into a Luttinger liquid at ambient temperature. The power-law exponent extracted from these fits reveals a significant increase above 200 K. It changes from ? = 0.6 at low temperature to ? = 1.0 at room temperature.

  16. Observation of a Helical Luttinger Liquid in InAs /GaSb Quantum Spin Hall Edges

    NASA Astrophysics Data System (ADS)

    Li, Tingxin; Wang, Pengjie; Fu, Hailong; Du, Lingjie; Schreiber, Kate A.; Mu, Xiaoyang; Liu, Xiaoxue; Sullivan, Gerard; Csáthy, Gábor A.; Lin, Xi; Du, Rui-Rui

    2015-09-01

    We report on the observation of a helical Luttinger liquid in the edge of an InAs /GaSb quantum spin Hall insulator, which shows characteristic suppression of conductance at low temperature and low bias voltage. Moreover, the conductance shows power-law behavior as a function of temperature and bias voltage. The results underscore the strong electron-electron interaction effect in transport of InAs /GaSb edge states. Because of the fact that the Fermi velocity of the edge modes is controlled by gates, the Luttinger parameter can be fine tuned. Realization of a tunable Luttinger liquid offers a one-dimensional model system for future studies of predicted correlation effects.

  17. Loschmidt echo and the many-body orthogonality catastrophe in a qubit-coupled Luttinger liquid.

    PubMed

    Dóra, Balázs; Pollmann, Frank; Fortágh, József; Zaránd, Gergely

    2013-07-26

    We investigate the many-body generalization of the orthogonality catastrophe by studying the generalized Loschmidt echo of Luttinger liquids (LLs) after a global change of interaction. It decays exponentially with system size and exhibits universal behavior: the steady state exponent after quenching back and forth n times between 2 LLs (bang-bang protocol) is 2n times bigger than that of the adiabatic overlap and depends only on the initial and final LL parameters. These are corroborated numerically by matrix-product state based methods of the XXZ Heisenberg model. An experimental setup consisting of a hybrid system containing cold atoms and a flux qubit coupled to a Feshbach resonance is proposed to measure the Loschmidt echo using rf spectroscopy or Ramsey interferometry. PMID:23931387

  18. Luttinger Liquid Behavior in a Quasi-One-Dimensional Transition Metal Oxide

    NASA Astrophysics Data System (ADS)

    Neumeier, John J.

    2008-05-01

    One-dimensional solids are attractive because of their inherent simplicity. However, theory shows that even weak Coulomb interactions in one dimension lead to strong perturbations, which can cause unusual physics, such as the separation of spin and charge and simple power-law dependencies of important physical properties. In this talk, I will provide an overview of the Lithium Purple Bronze, Li0.9Mo6O17 - a compound discovered over 20 years ago. Our recent work helps to understand the transition to superconductivity at 1.9 K as the result of a crossover to higher dimension, as predicted by theories for Luttinger Liquids. In addition, our group has shown that the introduction of defects causes Bose Metal behavior, where a lack of phase coherence leads to a metallic state instead of superconductivity. Possible physical connections to high temperature superconductors will be highlighted in the presentation.

  19. Approaching many-body localization from disordered Luttinger liquids via the functional renormalization group

    NASA Astrophysics Data System (ADS)

    Karrasch, C.; Moore, J. E.

    2015-09-01

    We study the interplay of interactions and disorder in a one-dimensional fermion lattice coupled adiabatically to infinite reservoirs. We employ both the functional renormalization group (FRG) as well as matrix product state techniques, which serve as an accurate benchmark for small systems. Using the FRG, we compute the length- and temperature-dependence of the conductance averaged over 104 samples for lattices as large as 105 sites. We identify regimes in which non-Ohmic power law behavior can be observed and demonstrate that the corresponding exponents can be understood by adapting earlier predictions obtained perturbatively for disordered Luttinger liquids. In the presence of both disorder and isolated impurities, the conductance has a universal single-parameter scaling form. This lays the groundwork for an application of the functional renormalization group to the realm of many-body localization.

  20. Quantum Spin Dynamics of Mode-Squeezed Luttinger Liquids in Two-Component Atomic Gases

    SciTech Connect

    Widera, Artur; Trotzky, Stefan; Cheinet, Patrick; Foelling, Simon; Gerbier, Fabrice; Bloch, Immanuel; Gritsev, Vladimir; Lukin, Mikhail D.; Demler, Eugene

    2008-04-11

    We report on the observation of many-body spin dynamics of interacting, one-dimensional (1D) ultracold bosonic gases with two spin states. By controlling the nonlinear atomic interactions close to a Feshbach resonance we are able to induce a phase diffusive many-body spin dynamics of the relative phase between the two components. We monitor this dynamical evolution by Ramsey interferometry, supplemented by a novel, many-body echo technique, which unveils the role of quantum fluctuations in 1D. We find that the time evolution of the system is well described by a Luttinger liquid initially prepared in a multimode squeezed state. Our approach allows us to probe the nonequilibrium evolution of one-dimensional many-body quantum systems.

  1. Quantum impurity in a Luttinger liquid: Universal conductance with entanglement renormalization

    NASA Astrophysics Data System (ADS)

    Lo, Ya-Lin; Hsieh, Yun-Da; Hou, Chang-Yu; Chen, Pochung; Kao, Ying-Jer

    2014-12-01

    We study numerically the universal conductance of Luttinger-liquid wire with a single impurity via the multiscale entanglement renormalization ansatz (MERA). The scale-invariant MERA provides an efficient way to extract scaling operators and scaling dimensions for both the bulk and the boundary conformal field theories. By utilizing the key relationship between the conductance tensor and ground-state correlation function, the universal conductance can be evaluated within the framework of the boundary MERA. We construct the boundary MERA to compute the correlation functions and scaling dimensions for the Kane-Fisher fixed points by modeling the single impurity as a junction (weak link) of two interacting wires. We show that the universal behavior of the junction can be easily identified within the MERA and argue that the boundary MERA framework has tremendous potential to classify the fixed points in general multiwire junctions.

  2. Time-resolved pure spin fractionalization and spin-charge separation in helical Luttinger liquid based devices

    NASA Astrophysics Data System (ADS)

    Calzona, Alessio; Carrega, Matteo; Dolcetto, Giacomo; Sassetti, Maura

    2015-11-01

    Helical Luttinger liquids, appearing at the edge of two-dimensional topological insulators, represent a new paradigm of one-dimensional systems, where peculiar quantum phenomena can be investigated. Motivated by recent experiments on charge fractionalization, we propose a setup based on helical Luttinger liquids that allows one to time-resolve, in addition to charge fractionalization, also spin-charge separation and pure spin fractionalization. This is due to the combined presence of spin-momentum locking and interactions. We show that electric time-resolved measurements can reveal both charge and spin properties, avoiding the need of magnetic materials. Although challenging, the proposed setup could be achieved with present-day technologies, promoting helical liquids as interesting playgrounds to explore the effects of interactions in one dimension.

  3. Duality of Weak and Strong Scatterer in Luttinger Liquid Coupled to Massless Bosons

    NASA Astrophysics Data System (ADS)

    Galda, Alexey; Yurkevich, Igor; Yevtushenko, Oleg; Lerner, Igor

    2013-03-01

    We study electronic transport in a Luttinger liquid (LL) with an embedded impurity, which is either a weak scatterer (WS) or a weak link (WL), when interacting electrons are coupled to one-dimensional massless bosons (e.g., acoustic phonons). The additional coupling competes with Coulomb interaction changing scaling exponents of various correlation functions. The impurity strength ? and the tunneling amplitude t in the WS and WL limits scale at low energies ? as: ? (?) ~?0? ?ws - 1 and t (?) ~t0? ?wl - 1 , correspondingly. We find that the duality relation between the scaling dimensions established for the standard LL, ?ws?wl = 1 , holds in the presence of the additional coupling for an arbitrary fixed strength of boson scattering from the impurity. As a result, at low temperatures the system remains either an ideal insulator or an ideal metal, regardless of the scattering strength. However, in the case when electron and boson scattering from the impurity are correlated, the system has a rich phase diagram that includes a metal-insulator transition at some intermediate values of the scattering. Leverhulme grant RPG-380, DFG through SFB TR-12, DoE Office of Science under the Contract No. DEAC02-06CH11357

  4. Density-functional studies of purple bronze: A paradigm Tomonaga-Luttinger liquid

    NASA Astrophysics Data System (ADS)

    Popovic, Zoran; Satpathy, Sashi

    2003-03-01

    Using density-functional band structure calculations, we examine the electronic structure of the purple bronze Li_0.9Mo_6O_17, which exhibits a quasi-one-dimensional Tomonaga-Luttinger liquid behavior. Most of the physical properties are governed by the peculiar double zigzag chains found in the crystal structure of this compound. Our calculations show that the most relevant states around the Fermi level (E_f), are formed from the 4d t_2g orbitals belonging to Mo atoms that are positioned on the zigzag chains. The overall shape and dispersion width of the bands around Ef are consistent with recent ARPES tearpes measurements. We determine the Fermi surface to consist of two slightly warped planes perpendicular to the direction of the zigzag chains. The calculated nesting vector is in very good agreement with the ARPES tearpes data. * Work supported by the U. S. Department of Energy. 00 [*]bymitPermanent address: Institute for Nuclear Sciences-``Vin?a'', PO Box: 522, 11001 Belgrade, Yugoslavia arpes G.-H. Gweon, et al., J. of Elect. Spect. and Related Phenomena, 117-118, 481 (2001) thebibliography

  5. Cluster Luttinger liquids and emergent supersymmetric conformal critical points in the one-dimensional soft-shoulder Hubbard model

    E-print Network

    M. Dalmonte; W. Lechner; Zi Cai; M. Mattioli; A. M. Läuchli; G. Pupillo

    2015-03-13

    We investigate the quantum phases of hard-core bosonic atoms in an extended Hubbard model where particles interact via soft-shoulder potentials in one dimension. Using a combination of field-theoretical methods and strong-coupling perturbation theory, we demonstrate that the low-energy phase can be a conformal cluster Luttinger liquid (CLL) phase with central charge $c=1$, where the microscopic degrees of freedom correspond to mesoscopic ensembles of particles. Using numerical density-matrix-renormalization-group methods, we demonstrate that the CLL phase, first predicted in [Phys. Rev. Lett. 111, 165302 (2013)], is separated from a conventional Tomonaga-Luttinger liquid by an exotic critical point with central charge $c=3/2$. The latter is expression of an emergent conformal supersymmetry, which is not present in the original Hamiltonian. We discuss the observability of the CLL phase in realistic experimental settings with weakly-dressed Rydberg atoms confined to optical lattices. Using quantum Monte-Carlo simulations, we show that the typical features of CLLs are stable up to comparatively high temperatures. Using exact diagonalizations and quantum trajectory methods, we provide a protocol for adiabatic state preparation as well as quantitative estimates on the effects of particle losses.

  6. Cluster Luttinger liquids and emergent supersymmetric conformal critical points in the one-dimensional soft-shoulder Hubbard model

    NASA Astrophysics Data System (ADS)

    Dalmonte, M.; Lechner, W.; Cai, Zi; Mattioli, M.; Läuchli, A. M.; Pupillo, G.

    2015-07-01

    We investigate the quantum phases of hard-core bosonic atoms in an extended Hubbard model where particles interact via soft-shoulder potentials in one dimension. Using a combination of field-theoretical methods and strong-coupling perturbation theory, we demonstrate that the low-energy phase can be a conformal cluster Luttinger liquid (CLL) phase with central charge c =1 , where the microscopic degrees of freedom correspond to mesoscopic ensembles of particles. Using numerical density-matrix renormalization-group methods, we demonstrate that the CLL phase [first predicted in M. Mattioli et al., Phys. Rev. Lett. 111, 165302 (2013), 10.1103/PhysRevLett.111.165302] is separated from a conventional Tomonaga-Luttinger liquid by an exotic critical point with central charge c =3/2 . The latter is expression of an emergent conformal supersymmetry, which is not present in the original Hamiltonian. We discuss the observability of the CLL phase in realistic experimental settings with weakly dressed Rydberg atoms confined to optical lattices. Using quantum Monte Carlo simulations, we show that the typical features of CLLs are stable up to comparatively high temperatures. Using exact diagonalizations and quantum trajectory methods, we provide a protocol for adiabatic state preparation as well as quantitative estimates on the effects of particle losses.

  7. New Luttinger-Liquid Physics from Photoemission on Li0.9Mo6O17

    SciTech Connect

    Wang, Feng; Alvarez, J V; Mo, S -K; Allen, J W; Gweon, G -H; He, J; Jin, Rongying; Mandrus, David; Hochst, H

    2006-01-01

    Temperature dependent high resolution photoemission spectra of quasi-one-dimensional Li{sub 0.9}Mo{sub 6}O{sub 17} evince a strong renormalization of its Luttinger-liquid density-of-states anomalous exponent. We trace this new effect to interacting charge neutral critical modes that emerge naturally from the two-band nature of the material. Li{sub 0.9}Mo{sub 6}O{sub 17} is shown thereby to be a paradigm material that is capable of revealing new Luttinger physics.

  8. Luttinger-Liquid signature in scanning tunneling spectra of Li0.9Mo6O17

    NASA Astrophysics Data System (ADS)

    Matzdorf, R.; Cazalilla, M. A.; Jin, R.; He, J.; Mandrus, D.

    2005-03-01

    We present low-temperature scanning tunneling spectroscopy data from the quasi one-dimensional purple bronze Li0.9Mo6O17. Our spectra show clearly a power-law behavior in density of states around Fermi-energy (-50meV < E < +50meV) with an exponent of ? = 0.6 . Temperature dependent spectra between T = 5K and 50K are well-described using a model that involves tunneling into a Luttinger-Liquid at finite temperature. We do not observe any signature in the density of states near T = 24K where a insulator-to-metal transition has been reported. Finally we will discuss our data within the model of a zero bias anomaly (ZBA). However, this model does not describe the experimental data as well as the Luttinger-model does. (Oak Ridge national Laboratory, managed by UT-Battelle, LLC, for the U.S. Dept. of Energy under contract DE-AC05-00OR22725)

  9. Universal Tomonaga-Luttinger liquid phases in one-dimensional strongly attractive SU(N) fermionic cold atoms

    SciTech Connect

    Guan, X. W.; Lee, J.-Y.; Batchelor, M. T.; Yin, X.-G.; Chen Shu

    2010-08-15

    A simple set of algebraic equations is derived for the exact low-temperature thermodynamics of one-dimensional multicomponent strongly attractive fermionic atoms with enlarged SU(N) spin symmetry and Zeeman splitting. Universal multicomponent Tomonaga-Luttinger liquid (TLL) phases are thus determined. For linear Zeeman splitting, the physics of the gapless phase at low temperatures belongs to the universality class of a two-component asymmetric TLL corresponding to spin-neutral N-atom composites and spin-(N-1)/2 single atoms. The equation of state which we obtained provides a precise description of multicomponent composite fermions and opens up the study of quantum criticality in one-dimensional systems of N-component Fermi gases with population imbalance.

  10. Luttinger Theorem for the Strongly Correlated Fermi Liquid of Composite Fermions

    NASA Astrophysics Data System (ADS)

    Balram, Ajit C.; T?ke, Csaba; Jain, J. K.

    2015-10-01

    While an ordinary Fermi sea is perturbatively robust to interactions, the paradigmatic composite-fermion (CF) Fermi sea arises as a nonperturbative consequence of emergent gauge fields in a system where there was no Fermi sea to begin with. A mean-field picture suggests two Fermi seas, of composite fermions made from electrons or holes in the lowest Landau level, which occupy different areas away from half filling and thus appear to represent distinct states. Using the microscopic theory of composite fermions, which satisfies particle-hole symmetry in the lowest Landau level to an excellent approximation, we show that the Fermi wave vectors at filling factors ? and 1 -? are equal when expressed in units of the inverse magnetic length, and are generally consistent with the experimental findings of Kamburov et al. [Phys. Rev. Lett. 113, 196801 (2014)]. Our calculations suggest that the area of the CF Fermi sea may slightly violate the Luttinger area rule.

  11. Elementary Excitations in Quantum Liquids.

    ERIC Educational Resources Information Center

    Pines, David

    1981-01-01

    Discusses elementary excitations and their role in condensed matter physics, focusing on quantum plasma, helium liquids, and superconductors. Considers research primarily conducted in the 1950s and concludes with a brief survey of some closely related further developments. (Author/JN)

  12. Momentum-resolved tunneling between a Luttinger liquid and a two-dimensional electron gas S. A. Grigera and A. J. Schofield

    E-print Network

    Grigera, Santiago

    . Grigera and A. J. Schofield School of Physics and Astronomy, University of Birmingham, Birmingham B15 2TT experimental signature of spin-charge separation. DOI: 10.1103/PhysRevB.69.245109 PACS number(s): 71.10.Pm, 72.20. i, 73.40.Gk I. INTRODUCTION Haldane's Luttinger-liquid hypothesis1--that all one- dimensional (1D

  13. Density-functional study of the Luttinger liquid behavior of the lithium molybdenum purple bronze Li0.9Mo6O17

    NASA Astrophysics Data System (ADS)

    Popovi?, Z. S.; Satpathy, S.

    2006-07-01

    Using density-functional calculations, we study the electronic structure of the purple bronze Li0.9Mo6O17 , which has been proposed to be a paradigm system for the Luttinger liquid behavior. Our results show that the quasi-one-dimensional (1D) electron bands crossing the Fermi energy originate from the Mo atoms on the double zigzag chains with predominant Mo (dxy) character and a Fermi surface that consists of two slightly warped planes, normal to the direction of the zigzag chains. The overall shape and dispersion of the bands as well as the calculated Fermi surface nesting vector are in excellent agreement with recent photoemission measurements. From constrained density-functional calculations of the Coulomb interactions and the calculated Fermi velocity, we estimate the values for the characteristic parameters of the Luttinger liquid, viz., the ratio of the spin-charge velocities to be v?/vs?1.8 and the anomalous dimension characterizing the Fermi surface discontinuity to be ??0.6 . The general agreement of these values with experiments further strengthens the case for the lithium molybdenum purple bronze as a Luttinger liquid.

  14. Transverse excitations in liquid metals

    NASA Astrophysics Data System (ADS)

    Hosokawa, S.; Munejiri, S.; Inui, M.; Kajihara, Y.; Pilgrim, W.-C.; Baron, A. Q. R.; Shimojo, F.; Hoshino, K.

    2013-02-01

    The transverse acoustic excitation modes were detected by inelastic x-ray scattering in liquid Ga, Cu and Fe in the Q range around 10 nm-1 using a third-generation synchrotron radiation facility, SPring-8, although these liquid metals are mostly described by a simple hard-sphere liquid. Ab initio molecular dynamics simulations clearly support this finding for liquid Ga. From the detailed analyses for the S(Q,?) spectra with good statistic qualities, the lifetime of less than 1 ps and the propagating length of less than 1 nm can be estimated for the transverse acoustic phonon modes, which correspond to the lifetime and size of cages formed instantaneously in these liquid metals. The microscopic Poisson's ratio estimated from the dynamic velocities of sound is 0.42 for liquid Ga and about -0.2 for liquid transition metals, indicating a rubber-like soft and extremely hard elastic properties of the cage clusters, respectively. The origin of these microscopic elastic properties is discussed in detail.

  15. Luttinger-liquid theory of purple bronze Li0.9Mo6O17 in the charge regime

    NASA Astrophysics Data System (ADS)

    Chudzinski, P.; Jarlborg, T.; Giamarchi, T.

    2012-08-01

    Molybdenum purple bronze Li0.9Mo6O17 is an exceptional material known to exhibit one-dimensional (1D) properties for energies down to a few meV. This fact seems to be well established both in experiments and in band structure theory. We use the unusual, very 1D band dispersion obtained in ab initio DFT-LMTO band calculations as our starting point to study the physics emerging below 300 meV. A dispersion perpendicular to the main dispersive direction is obtained and investigated in detail. Based on this, we derive an effective low-energy theory within the Tomonaga-Luttinger liquid (TLL) framework. We estimate the strength of the possible interactions and from this deduce the values of the TLL parameters for charge modes. Finally, we investigate possible instabilities of TLL by deriving renormalization group equations which allow us to predict the size of potential gaps in the spectrum. While 2kF instabilities strongly suppress each other, the 4kF instabilities cooperate, which paves the way for a possible charge-density wave at the lowest energies. The aim of this work is to understand the experimental findings, in particular the ones which are certainly lying within the 1D regime. We discuss the validity of our 1D approach and further perspectives for the lower-energy phases.

  16. Wilson ratio of a Tomonaga-Luttinger liquid in the one-dimensional spin- 1 / 2 Heisenberg antiferromagnet CuPzN

    NASA Astrophysics Data System (ADS)

    Aoyama, Christopher; Kono, Yohei; Marino, Kristen; Zhou, Haidong; Hotta, Chisa; Turnbull, Mark; Landee, Christopher; Sakakibara, Toshiro; Takano, Yasumasa

    2015-03-01

    In the Tomonaga-Luttinger liquid (TLL) phase of a one-dimensional antiferromagnet, the Wilson ratio and the TLL parameter, K, are one and the same except for a trivial numerical factor. This equivalence allows the determination of K from magnetic susceptibility and specific heat. We have performed accurate magnetization and specific-heat measurements on the quasi-one-dimensional spin-1/2 Heisenberg antiferromagnet Cu(C4H4N2)(NO3)2, known as CuPzN, at temperatures between 80 mK and 7.5 K and in magnetic fields up to 14.7 T and, from the data in the TLL regime, have obtained K as a function of the magnetic field. The results are in excellent agreement with a prediction based on the Bethe ansatz.

  17. Equilibration of a one-dimensional quantum liquid

    SciTech Connect

    Matveev, K. A.

    2013-09-15

    We review some of the recent results on equilibration of one-dimensional quantum liquids. The low-energy properties of these systems are described by the Luttinger liquid theory, in which the excitations are bosonic quasiparticles. At low temperatures, the relaxation of the gas of excitations toward full equilibrium is exponentially slow. In electronic Luttinger liquids, these relaxation processes involve backscattering of electrons and give rise to interesting corrections to the transport properties of one-dimensional conductors. We focus on the phenomenological theory of the equilibration of a quantum liquid and obtain an expression for the relaxation rate in terms of the excitation spectrum.

  18. Elementary Excitations in Quantum Fermi Liquid

    E-print Network

    Nodar L. Tsintsadze; Levan N. Tsintsadze

    2010-06-02

    Landau's theory of Fermi liquids is generalized by incorporating the de Broglie waves diffraction. A newly derived kinetic equation of the Fermi particles is used to derive a general dispersion relation and the excitation of zero sound is studied. A new mode is found due to the quantum correction. It is shown that the zero sound can exist even in an ideal Fermi gas. We also disclose a new branch of frequency spectrum due to the weak interaction.

  19. Elementary excitations and flow in the liquid

    NASA Astrophysics Data System (ADS)

    Egami, Takeshi

    2013-03-01

    A new mode of excitation is introduced to elucidate the dynamics in simple liquids at the atomic scale. Some properties of liquid defy easy explanations. For instance, in liquids phonons are overdamped with a very short lifetime. Nevertheless the Dulong-Petit law (CV ~ 3kB) is widely observed at high temperatures. As temperature is reduced the specific heat markedly increases in the supercooled state, only to drop down sharply at the glass transition. Viscosity shows an Arrhenian behavior at high temperatures, but increases rapidly toward the glass transition in the supercooled state. We suggest that these perplexing observations can be naturally explained in terms of the local configurational excitations (LCE's) which locally change the atomic connectivity by an atom losing or gaining one nearest neighbor. We show that the lifetime of LCE, ?LC, is equal to the Maxwell relaxation time, ?M, at temperatures above the crossover temperature, TA. Above TA the phonon mean-free path, ? =cT?LC , where cT is the transverse sound velocity, becomes shorter than the interatomic distance, resulting in phonon localization. Therefore LCE's are the elementary excitations in the liquid. They are independent of each other above TA, but below TA LCE's interact through phonon exchange, resulting in the rapid increase in ?M , culminatingintheglasstransition . LCE' sarealsothemechanism of flow at low temperature under strong shear stress. In this case, however, losing and gaining of the neighbors are strongly coupled, so that ?M = LC / 2 [ 1 ] . Wealsodiscussdynamicheterogeneityin terms of LCE interactions. This work was supported by the U.S. Department of Energy, Office of Basic Energy Sciences, Materials Science and Engineering Division.

  20. Ion-beam excitation of liquid argon

    E-print Network

    Hofmann, M; Heindl, T; Neumeier, A; Oberauer, L; Potzel, W; Roth, S; Schönert, S; Wieser, J; Ulrich, A

    2015-01-01

    The scintillation light of liquid argon has been recorded wavelength and time resolved with very good statistics in a wavelength interval ranging from 118 nm through 970 nm. Three different ion beams, protons, sulfur ions and gold ions, were used to excite liquid argon. Only minor differences were observed in the wavelength-spectra obtained with the different incident particles. Light emission in the wavelength range of the third excimer continuum was found to be strongly suppressed in the liquid phase. In time-resolved measurements, the time structure of the scintillation light can be directly attributed to wavelength in our studies, as no wavelength shifter has been used. These measurements confirm that the singlet-to-triplet intensity ratio in the second excimer continuum range is a useful parameter for particle discrimination, which can also be employed in wavelength-integrated measurements as long as the sensitivity of the detector system does not rise steeply for wavelengths longer than 190 nm. Using ou...

  1. Excited state dynamics of liquid water: Insight from the dissociation reaction following two-photon excitation

    E-print Network

    Elles, Christopher G.; Shkrob, Ilya A.; Crowell, Robert A.; Bradforth, Stephen E.

    2007-04-25

    The authors use transient absorption spectroscopy to monitor the ionization and dissociation products following two-photon excitation of pure liquid water. The primary decay mechanism changes from dissociation at an excitation energy of 8.3e...

  2. Multiphoton ionization and excitation spectroscopy of molecules in liquids. [Fluoranthene

    SciTech Connect

    Siomos, K.; Faidas, H.; Christophorou, L.G.

    1984-01-01

    The two-photon ionization and excitation spectra of fluoranthene in liquid n-pentane have been measured and together with laser power versus signal intensity measurements have been utilized to elucidate the multiphoton ionization mechanism for this and other molecules in liquids.

  3. Ionization and Excitation in Non-Polar Organic Liquids.

    ERIC Educational Resources Information Center

    Lipsky, Sanford

    1981-01-01

    Reviews recent advances in radiation chemistry concerning the effect of high-energy radiation on organic liquids. Discusses the general nature of excited and ionized states, pathways for decay, the effect of environmental perturbation, the behavior of an electron in a nonpolar liquid, and comparison of photochemical and radiation chemical effects.…

  4. Elementary excitations of liquid 4 He in aerogel

    E-print Network

    Glyde, Henry R.

    defects introduce disorder.8­11 In this case the melting of the flux line lattice is substantially changed materials. Superfluid flow and sound propagation in liquid 4 He is qualitatively changed by disorder.7Elementary excitations of liquid 4 He in aerogel O. Plantevin and B. Fa°k Commissariat a` l

  5. Finite-temperature coupled-cluster, many-body perturbation, and restricted and unrestricted Hartree-Fock study on one-dimensional solids: Luttinger liquids, Peierls transitions, and spin- and charge-density waves

    NASA Astrophysics Data System (ADS)

    Hermes, Matthew R.; Hirata, So

    2015-09-01

    One-dimensional (1D) solids exhibit a number of striking electronic structures including charge-density wave (CDW) and spin-density wave (SDW). Also, the Peierls theorem states that at zero temperature, a 1D system predicted by simple band theory to be a metal will spontaneously dimerize and open a finite fundamental bandgap, while at higher temperatures, it will assume the equidistant geometry with zero bandgap (a Peierls transition). We computationally study these unique electronic structures and transition in polyyne and all-trans polyacetylene using finite-temperature generalizations of ab initio spin-unrestricted Hartree-Fock (UHF) and spin-restricted coupled-cluster doubles (CCD) theories, extending upon previous work [He et al., J. Chem. Phys. 140, 024702 (2014)] that is based on spin-restricted Hartree-Fock (RHF) and second-order many-body perturbation (MP2) theories. Unlike RHF, UHF can predict SDW as well as CDW and metallic states, and unlike MP2, CCD does not diverge even if the underlying RHF reference wave function is metallic. UHF predicts a gapped SDW state with no dimerization at low temperatures, which gradually becomes metallic as the temperature is raised. CCD, meanwhile, confirms that electron correlation lowers the Peierls transition temperature. Furthermore, we show that the results from all theories for both polymers are subject to a unified interpretation in terms of the UHF solutions to the Hubbard-Peierls model using different values of the electron-electron interaction strength, U/t, in its Hamiltonian. The CCD wave function is shown to encompass the form of the exact solution of the Tomonaga-Luttinger model and is thus expected to describe accurately the electronic structure of Luttinger liquids.

  6. Gravity jitter excited cryogenic liquid slosh waves in microgravity environment

    NASA Technical Reports Server (NTRS)

    Hung, R. J.; Lee, C. C.; Leslie, F. W.

    1991-01-01

    The dynamical behavior of fluids, in particular the effect of surface tension on partially-filled rotating fluids (cryogenic liquid helium and helium vapor) in a full-scale Gravity Probe-B Spacecraft liquid helium container tank without probe imposed by various frequencies of gravity jitter have been investigated. Results disclose the conditions for the excitation of large amplitude slosh waves which should be avoided in the design of cryogenic liquid propellant system.

  7. Excitations in Liquid HELIUM-4 Films.

    NASA Astrophysics Data System (ADS)

    Tymczak, Christopher John

    1995-01-01

    We use the hypernetted chain (HNC) variational theory for inhomogeneous systems to study the excitations in ^4He films adsorbed to a graphite substrate. The first part of this dissertation describes the HNC variational theory and how it is used to calculate the physical properties of ^4He films. We then extend the theory to describe excitations in these films. The simplest implementation of the theory, which assumes time-dependent one-body correlations only, is the generalization of Feynman's theory of excitations to inhomogeneous geometries. We then include time-dependent fluctuations of the two-body correlations. This leads to two important improvements of the theory. First, the predictions of the new theory agree significantly better with experiments. Second, since the now theory also allows for damping effects, we can calculate the lifetimes of individual excitations. Insight can be gained into the physical nature of the film's excited states by studying the transition densities and the probability currents. We describe how these quantities can be calculated within the generalized theory of excitations, and present results for mono-, double -, and triple-layer films.

  8. Tomonaga–Luttinger physics in electronic quantum circuits

    PubMed Central

    Jezouin, S.; Albert, M.; Parmentier, F. D.; Anthore, A.; Gennser, U.; Cavanna, A.; Safi, I.; Pierre, F.

    2013-01-01

    In one-dimensional conductors, interactions result in correlated electronic systems. At low energy, a hallmark signature of the so-called Tomonaga–Luttinger liquids is the universal conductance curve predicted in presence of an impurity. A seemingly different topic is the quantum laws of electricity, when distinct quantum conductors are assembled in a circuit. In particular, the conductances are suppressed at low energy, a phenomenon called dynamical Coulomb blockade. Here we investigate the conductance of mesoscopic circuits constituted by a short single-channel quantum conductor in series with a resistance, and demonstrate a proposed link to Tomonaga–Luttinger physics. We reformulate and establish experimentally a recently derived phenomenological expression for the conductance using a wide range of circuits, including carbon nanotube data obtained elsewhere. By confronting both conductance data and phenomenological expression with the universal Tomonaga–Luttinger conductance curve, we demonstrate experimentally the predicted mapping between dynamical Coulomb blockade and the transport across a Tomonaga–Luttinger liquid with an impurity. PMID:23653214

  9. Nuclear collective excitations in Landau Fermi liquid theory

    E-print Network

    Bao-Xi Sun

    2010-03-08

    The nuclear collective excitations are studied within Landau Fermi liquid theory. By using the nucleon-nucleon interaction of the linear sigma-omega model, the nuclear collective excitation energies of different values of $l$ are obtained, which are fitted with the centroid energies of the giant resonances of spherical nuclei, respectively. In addition, it is pointed out that the isovector giant resonances except l=1 correspond to the modes that protons are in the creation state and neutrons are in the annihilation state, and vice versa. Some mixtures of the nuclear collective excitation states with different values of l are predicted.

  10. Transverse excitations in liquid Fe, Cu and Zn

    NASA Astrophysics Data System (ADS)

    Hosokawa, S.; Inui, M.; Kajihara, Y.; Tsutsui, S.; Baron, A. Q. R.

    2015-05-01

    Transverse acoustic (TA) excitation modes were observed in inelastic x-ray scattering spectra of liquid Fe, Cu and Zn. From the analysis of current correlation functions, we concluded that TA excitation modes can experimentally be detected through the quasi-TA branches in the longitudinal current correlation spectra in these liquid metals. The microscopic elastic constants are estimated and a characteristic difference from macroscopic polycrystalline value was found in Poisson's ratio of liquid Fe, which shows an extremely softer value of ?0.38 compared with the macroscopic value of ?0.275. The lifetime of the TA modes were determined to be ?0.45 ps for liquid Fe and Cu and ?0.55 ps for liquid Zn, reflecting different interatomic correlations between liquid transition metals and non-transition metals. The propagation length of the TA modes are ?0.85 nm in all of liquid metals, corresponding to the size of icosahedral or similar size of cages formed instantaneously in these liquid metals.

  11. The liquid to vapor phase transition in excited nuclei

    E-print Network

    J. B. Elliott; L. G. Moretto; L. Phair; G. J. Wozniak; T. Lefort; L. Beaulieu; K. Kwiatkowski; W. -C. Hsi; L. Pienkowski; H. Breuer; R. G. Korteling; R. Laforest; E. Martin; E. Ramakrishnan; D. Rowland; A. Ruangma; V. E. Viola; E. Winchester; S. J. Yennello

    2001-05-02

    For many years it has been speculated that excited nuclei would undergo a liquid to vapor phase transition. For even longer, it has been known that clusterization in a vapor carries direct information on the liquid- vapor equilibrium according to Fisher's droplet model. Now the thermal component of the 8 GeV/c pion + 197Au multifragmentation data of the ISiS Collaboration is shown to follow the scaling predicted by Fisher's model, thus providing the strongest evidence yet of the liquid to vapor phase transition.

  12. The liquid to vapor phase transition in excited nuclei

    SciTech Connect

    Elliott, J.B.; Moretto, L.G.; Phair, L.; Wozniak, G.J.; Beaulieu, L.; Breuer, H.; Korteling, R.G.; Kwiatkowski, K.; Lefort, T.; Pienkowski, L.; Ruangma, A.; Viola, V.E.; Yennello, S.J.

    2001-05-08

    For many years it has been speculated that excited nuclei would undergo a liquid to vapor phase transition. For even longer, it has been known that clusterization in a vapor carries direct information on the liquid-vapor equilibrium according to Fisher's droplet model. Now the thermal component of the 8 GeV/c pion + 197 Au multifragmentation data of the ISiS Collaboration is shown to follow the scaling predicted by Fisher's model, thus providing the strongest evidence yet of the liquid to vapor phase transition.

  13. Excitability and pattern formation in a liquid crystal FabryPerot interferometer

    E-print Network

    Wang, Peng-Ye

    Excitability and pattern formation in a liquid crystal Fabry±Perot interferometer Peng-Ye Wang a±Perot interferometer with a nematic liquid crystal to be an optical excitable system. The excitability is shown features of excitability in this system when it is spatially extended, namely, propagating pulses in one

  14. Excitations in liquid ^4He in Geltech silica

    NASA Astrophysics Data System (ADS)

    Plantevin, O.; Schober, H.; Glyde, Henry; Mulders, N.; Bjorn, Fak; Bossy, J.; Albergamo, F.

    2002-03-01

    We have measured the elementary excitations of liquid ^4He confined in Geltech silica for temperatures between 35 mK and 2.5 K using inelastic neutron scattering techniques. Geltech is a 40-50% porous media having 25 Ådiameter pores with at most few percent of the volume made up of larger pores of diameter less than 70 ÅWe observe well defined phonon-roton (p-r) excitations at all wave vectors Q investigated (0.4<= Q <= 2.1 ÅAlso observed are 2D layer modes propagating in the liquid layers adjacent to the media walls. These 2D modes are identified as layer modes by measuring the dynamical structure factor of liquid ^4He as a function of filling of the Geltech. At full filling the energies and lifetimes of the 3D p-r modes are the same as those in superfluid ^4He within the current precision. Most interestingly, we observe a well defined p-r excitation above the superfluid-normal transition Tc =0.725 K as determined in a torsional oscillator measurement(S. Miyamoto and Y. Takano, Czech. J. Phys. 46), 137 (1996). Observation of a well defined maxon-roton above Tc in Geltech suggests, as in the case of Vycor(H. R. Glyde, O. Plantevin, B. Fåk, G. Coddens, P. S. Danielson, and H. Schober, Phys. Rev. Lett. 84), 2646 (2000), that there can be localized Bose-Einstein condensation in porous media with phase coherence on short-length scales above the macroscopic superfluid transition temperature.

  15. Collective Excitations of Holographic Quantum Liquids in a Magnetic Field

    E-print Network

    Daniel K. Brattan; Richard A. Davison; Simon A. Gentle; Andy O'Bannon

    2012-08-31

    We use holography to study N=4 supersymmetric SU(Nc) Yang-Mills theory in the large-Nc and large-coupling limits coupled to a number Nf > T,\\sqrt{B}. We study the collective excitations of these holographic quantum liquids by computing the poles in the retarded Green's function of the baryon number charge density operator and the associated peaks in the spectral function. We focus on the evolution of the collective excitations as we increase the frequency relative to T, i.e. the hydrodynamic/collisionless crossover. We find that for all B, at low frequencies the tallest peak in the spectral function is associated with hydrodynamic charge diffusion. At high frequencies the tallest peak is associated with a sound mode similar to the zero sound mode in the collisionless regime of a Landau Fermi liquid. The sound mode has a gap proportional to B, and as a result for intermediate frequencies and for B sufficiently large compared to T the spectral function is strongly suppressed. We find that the hydrodynamic/collisionless crossover occurs at a frequency that is approximately B-independent.

  16. Dissociative ionization of liquid water induced by vibrational overtone excitation

    SciTech Connect

    Natzle, W.C.

    1983-03-01

    Photochemistry of vibrationally activated ground electronic state liquid water to produce H/sup +/ and OH/sup -/ ions has been initiated by pulsed, single-photon excitation of overtone and combination transitions. Transient conductivity measurements were used to determine quantum yields as a function of photon energy, isotopic composition, and temperature. The equilibrium relaxation rate following perturbation by the vibrationally activated reaction was also measured as a function of temperature reaction and isotopic composition. In H/sub 2/O, the quantum yield at 283 +- 1 K varies from 2 x 10/sup -9/ to 4 x 10/sup -5/ for wave numbers between 7605 and 18140 cm/sup -1/. In D/sub 2/O, the dependence of quantum yield on wavelength has the same qualitative shape as for H/sub 2/O, but is shifted to lower quantum yields. The position of a minimum in the quantum yield versus hydrogen mole fraction curve is consistent with a lower quantum yield for excitation of HOD in D/sub 2/O than for excitation of D/sub 2/O. The ionic recombination distance of 5.8 +- 0.5 A is constant within experimental error with temperature in H/sub 2/O and with isotopic composition at 25 +- 1/sup 0/C.

  17. One-dimensional Hubbard-Luttinger model for carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Ishkhanyan, H. A.; Krainov, V. P.

    2015-06-01

    A Hubbard-Luttinger model is developed for qualitative description of one-dimensional motion of interacting Pi-conductivity-electrons in carbon single-wall nanotubes at low temperatures. The low-lying excitations in one-dimensional electron gas are described in terms of interacting bosons. The Bogolyubov transformation allows one to describe the system as an ensemble of non-interacting quasi-bosons. Operators of Fermi excitations and Green functions of fermions are introduced. The electric current is derived as a function of potential difference on the contact between a nanotube and a normal metal. Deviations from Ohm law produced by electron-electron short-range repulsion as well as by the transverse quantization in single-wall nanotubes are discussed. The results are compared with experimental data.

  18. Liquid hydrogen suction dip and slosh wave excitation during draining under normal and reduced gravity environments

    NASA Technical Reports Server (NTRS)

    Hung, R. J.; Shyu, K. L.

    1992-01-01

    The paper discusses the dynamical behavior of vapor ingestion, liquid residual at the incipience of suction dip, slosh wave excitation under normal and reduced gravity and different flow rates during liquid hydrogen draining. Liquid residuals at the incipience of suction dip increase as the values of gravity decrease. Also liquid residuals increase with the draining flow rates. Lower ratio of Bond number and Weber number are unable to excite slosh waves. Lower flow rates and higher gravity excites waves with lower frequencies and higher wave amplitude slosh waves.

  19. Excitations Are Localized and Relaxation Is Hierarchical in Glass-Forming Liquids Aaron S. Keys

    E-print Network

    Garrahan, Juan P.

    Excitations Are Localized and Relaxation Is Hierarchical in Glass-Forming Liquids Aaron S. Keys importance sampling of trajectory space to study the structure, statistics, and dynamics of excitations responsible for structural relaxation. Excitations are detected in terms of persistent particle displacements

  20. COVER IMAGE The TomonagaLuttinger liquid

    E-print Network

    Loss, Daniel

    the wave David Gevaux 749 Oxide interfaces: Moment of magnetism Andrew J. Millis 750 Glass physics that these fields can give rise to an analogue of the Aharonov­ Bohm effect, a phenomenon that might be used

  1. Slosh wave excitation due to cryogenic liquid reorientation in space-based propulsion system

    NASA Technical Reports Server (NTRS)

    Hung, R. J.; Shyu, K. L.; Lee, C. C.

    1991-01-01

    The objective of the cryogenic fluid management of the spacecraft propulsion system is to develop the technology necessary for acquistion or positioning of liquid and vapor within a tank in reduced gravity to enable liquid outflow or vapor venting. In this study slosh wave excitation induced by the resettling flow field activated by 1.0 Hz medium frequency impulsive reverse gravity acceleration during the course of liquid fluid reorientation with the initiation of geyser for liquid filled levels of 30, 50, and 80 percent have been studied. Characteristics of slosh waves with various frequencies excited are discussed.

  2. Magnetoelastic excitations in the pyrochlore spin liquid Tb2Ti2O7.

    PubMed

    Fennell, T; Kenzelmann, M; Roessli, B; Mutka, H; Ollivier, J; Ruminy, M; Stuhr, U; Zaharko, O; Bovo, L; Cervellino, A; Haas, M K; Cava, R J

    2014-01-10

    At low temperatures, Tb2Ti2O7 enters a spin liquid state, despite expectations of magnetic order and/or a structural distortion. Using neutron scattering, we have discovered that in this spin liquid state an excited crystal field level is coupled to a transverse acoustic phonon, forming a hybrid excitation. Magnetic and phononlike branches with identical dispersion relations can be identified, and the hybridization vanishes in the paramagnetic state. We suggest that Tb2Ti2O7 is aptly named a "magnetoelastic spin liquid" and that the hybridization of the excitations suppresses both magnetic ordering and the structural distortion. The spin liquid phase of Tb2Ti2O7 can now be regarded as a Coulomb phase with propagating bosonic spin excitations. PMID:24483925

  3. Liquid hydrogen slosh waves excited by constant reverse gravity acceleration of geyser initiation

    NASA Technical Reports Server (NTRS)

    Hung, R. J.; Shyu, K. L.; Lee, C. C.

    1992-01-01

    The requirement to settle or to position liquid fuel over the outlet end of the spacecraft propellant tank before main engine restart poses a microgravity fluid behavior problem. Resettlement or reorientation of liquid propellant can be accomplished by providing the optimal acceleration to the spacecraft such that the propellant is reoriented over the tank outlet. In this study slosh wave excitation induced by the resettling flowfield during the course of liquid reorientation with the initiation of geyser for liquid-filled levels of 30, 50, 65, 70, and 80 percent have been studied. Characteristics of slosh waves with various frequencies excited are discussed. Slosh wave excitations will affect the fluid stress distribution exerted on the container wall and shift the fluid mass distribution inside the container, which imposes the time-dependent variations in the moment of inertia of the container. This information is important for the spacecraft control during the course of liquid reorientation.

  4. Boson localization and excitations of liquid 4 He confined in gelsil

    E-print Network

    Glyde, Henry R.

    neutron scattering measurements of the phonon-roton P-R modes of liquid 4 He at saturated vapor pressure confined in 44 Å mean pore diameter gelsil in the wave vector range 0.4 Q 2.15 Å-1 . Layer modes, modes comparisons with predictions. In contrast, mea- surement of the excitations of liquid 4 He in porous media has

  5. Fractionalized charge excitations in a spin liquid on partially filled pyrochlore lattices.

    PubMed

    Chen, Gang; Kee, Hae-Young; Kim, Yong Baek

    2014-11-01

    We study the Mott transition from a metal to cluster Mott insulators in the 1/4- and 1/8-filled pyrochlore lattice systems [corrected]. It is shown that such Mott transitions can arise due to charge localization in clusters or in tetrahedron units, driven by the nearest-neighbor repulsive interaction. The resulting cluster Mott insulator is a quantum spin liquid with a spinon Fermi surface, but at the same time a novel fractionalized charge liquid with charge excitations carrying half the electron charge. There exist two emergent U(1) gauge fields or "photons" that mediate interactions between spinons and charge excitations, and between fractionalized charge excitations themselves, respectively. In particular, it is suggested that the emergent photons associated with the fractionalized charge excitations can be measured in x-ray scattering experiments. Various other experimental signatures of the exotic cluster Mott insulator are discussed in light of candidate materials with partially filled bands on the pyrochlore lattice. PMID:25415920

  6. Optical nanoscopy with excited state saturation at liquid helium temperatures

    NASA Astrophysics Data System (ADS)

    Yang, B.; Trebbia, J.-B.; Baby, R.; Tamarat, Ph.; Lounis, B.

    2015-10-01

    Optical resolution of solid-state single quantum emitters at the nanometre scale is a challenging step towards the control of delocalized states formed by strongly and coherently interacting emitters. We have developed a simple super-resolution optical microscopy method operating at cryogenic temperatures, which is based on optical saturation of the excited state of single fluorescent molecules with a doughnut-shaped beam. Sub-10 nm resolution is achieved with extremely low excitation intensities, a million times lower than those used in room-temperature stimulated emission depletion microscopy. Compared with super-localization approaches, our technique offers a unique opportunity to super-resolve single molecules with overlapping optical resonance frequencies and paves the way to the study of coherent interactions between single emitters and to the manipulation of their degree of entanglement.

  7. Optically excited XeF* excimer laser in liquid argon

    SciTech Connect

    Shahidi, M.; Jara, H.; Pummer, H.; Egger, H.; Rhodes, C.K.

    1985-09-01

    Stimulated emission on the B..-->..X band of the XeF* molecule in the liquid phase at 404 nm was observed following transverse optical pumping at 351 nm. The energy of this emission was measured to be approx.70 ..mu..J, and the pulse had a FWHM of approx.5 nsec. The stimulated-emission spectrum showed considerable narrowing compared with the spontaneous-emission spectrum. The temporal behavior of the 404-nm pulse was investigated, and gain saturation of the lasing medium was observed.

  8. Excited-State Dynamics of Diindenoperylene in Liquid Solution and in Solid Films

    E-print Network

    Schreiber, Frank

    Excited-State Dynamics of Diindenoperylene in Liquid Solution and in Solid Films Valerie M. Nichols%) survives in longer-lived trap or defect states. The rapid internal conversion leads to transient heating that results in a derivative line shape in the transient absorption signal at longer delays. DIP does

  9. On the Kohn-Luttinger conundrum

    SciTech Connect

    Hirata, So; He Xiao

    2013-05-28

    Kohn and Luttinger [Phys. Rev. 118, 41 (1960)] showed that the conventional finite-temperature extension of the second-order many-body perturbation theory had the incorrect zero-temperature limit in metals and, on this basis, argued that the theory was incorrect. We show that this inconsistency arises from the noninclusion of the temperature effect in the energies of the zeroth-order eigenstates of the perturbation theory, which causes not only the Kohn-Luttinger conundrum but also another inconsistency with the zero-temperature many-body perturbation theory, namely, the different rates of divergence of the correlation energy in a homogeneous electron gas (HEG). We propose a renormalized many-body perturbation theory derivable from the finite-temperature extension of the normal-ordered second quantization applied to the denominators of the energy expression, which involves the energies of the zeroth-order states, as well as to the numerators. The renormalized theory is shown to have the correct zero-temperature limit and the same rate of divergence in a HEG as the zero-temperature counterpart, and is, therefore, the correct finite-temperature many-body perturbation theory.

  10. Enhanced efficiency in the excitation of higher modes for atomic force microscopy and mechanical sensors operated in liquids

    SciTech Connect

    Penedo, M. Hormeño, S.; Fernández-Martínez, I.; Luna, M.; Briones, F.; Raman, A.

    2014-10-27

    Recent developments in dynamic Atomic Force Microscopy where several eigenmodes are simultaneously excited in liquid media are proving to be an excellent tool in biological studies. Despite its relevance, the search for a reliable, efficient, and strong cantilever excitation method is still in progress. Herein, we present a theoretical modeling and experimental results of different actuation methods compatible with the operation of Atomic Force Microscopy in liquid environments: ideal acoustic, homogeneously distributed force, distributed applied torque (MAC Mode™), photothermal and magnetostrictive excitation. From the analysis of the results, it can be concluded that magnetostriction is the strongest and most efficient technique for higher eigenmode excitation when using soft cantilevers in liquid media.

  11. Enhanced efficiency in the excitation of higher modes for atomic force microscopy and mechanical sensors operated in liquids

    NASA Astrophysics Data System (ADS)

    Penedo, M.; Raman, A.; Hormeño, S.; Fernández-Martínez, I.; Luna, M.; Briones, F.

    2014-10-01

    Recent developments in dynamic Atomic Force Microscopy where several eigenmodes are simultaneously excited in liquid media are proving to be an excellent tool in biological studies. Despite its relevance, the search for a reliable, efficient, and strong cantilever excitation method is still in progress. Herein, we present a theoretical modeling and experimental results of different actuation methods compatible with the operation of Atomic Force Microscopy in liquid environments: ideal acoustic, homogeneously distributed force, distributed applied torque (MAC Mode™), photothermal and magnetostrictive excitation. From the analysis of the results, it can be concluded that magnetostriction is the strongest and most efficient technique for higher eigenmode excitation when using soft cantilevers in liquid media.

  12. Excitations in a thin liquid {sup 4}He film from inelastic neutron scattering

    SciTech Connect

    Clements, B.E.; Godfrin, H.; Krotscheck, E.; Lauter, H.J.; Leiderer, P.; Passiouk, V.; Tymczak, C.J.

    1996-05-01

    We perform a thorough analysis of the experimental dynamic structure function measured by inelastic neutron scattering for a low-temperature ({ital T}=0.65 K) four-layer liquid {sup 4}He film. The results are interpreted in light of recent theoretical calculations of the (nonvortex) excitations in thin liquid Bose films. The experimental system consists of four outer liquid layers, adsorbed to two solid inner {sup 4}He layers, which are themselves adsorbed to a graphite substrate. Relatively intense surface (ripplon) and bulklike modes are observed. The analysis of the experimental data gives strong evidence for still other modes and supports the long-standing theoretical predictions of layerlike modes (layer phonons) associated with excitations propagating primarily within the liquid layers comprising the film. The results of the analysis are consistent with the occurrence of level crossings between modes, and the existence of a layer modes for which the theory predicts will propagate in the vicinity of the solid-liquid interface. The theory and experiment agree on the detailed nature of the ripplon; its dispersion at low momenta, its fall off in intensity at intermediate momenta, and the level crossings at high momentum. Similar to experiment, the theory yields an intense mode in the maxon-roton region which is intrepreted as the formation of the bulklike excitation. {copyright} {ital 1996 The American Physical Society.}

  13. Slosh wave excitation of cryogenic liquid helium in gravity Probe-B rotating dewar

    NASA Technical Reports Server (NTRS)

    Hung, R. J.; Lee, C. C.; Leslie, F. W.

    1991-01-01

    The dynamical behavior of fluids, in particular the effect of surface tension on partially-filled rotating fluids (cryogenic liquid helium and helium vapor) in a full scale Gravity Probe-B Spacecraft propellant dewar tank imposed by various frequencies of gravity jitters have been investigated. Fluid stress distribution, caused by the excitation of slosh waves and their associated large amplitude disturbances on the liquid-vapor interface, exerted on the outer and inner walls of rotating dewar container also have been investigated. Results show that fluid stress distribution exerted on the outer and inner walls of rotating dewar are closely related to the characteristics of slosh waves excited on the liquid-vapor interface in the rotating dewar tank.

  14. Slosh wave and geyser excitations due to liquid hydrogen shut-off during draining in microgravity

    NASA Technical Reports Server (NTRS)

    Hung, R. J.; Shyu, K. L.

    1995-01-01

    The dynamical behavior of liquid hydrogen shut-off during draining, and shut-off at the moment of the incipience of a suction dip have been investigated. It shows that a large amplitude surge is observed for liquid in the container at the moment of liquid hydrogen shut-off in reduced gravity. It also shows that slosh waves accompanied by a strong geyser are developed for surge-related flow fields induced by liquid hydrogen shut-off at the incipience of a suction dip. In the slosh wave excitation, both a lower gravity environment and higher flow rate before the shut-off of liquid draining are resonsible for the initiation of greater amplitude slosh waves. Slosh wave excitation, due to shut-off during liquid hydrogen draining, shift the fluid mass distribution in the container which imposes time-dependent variation in the spacecraft moment of inertia. This provides important information necessary for on-orbit guidance and attitude control of spacecraft.

  15. Liquid draining shut-off induced geyser and slosh wave excitation at suction dip during draining in microgravity

    NASA Technical Reports Server (NTRS)

    Hung, R. J.; Shyu, K. L.

    1992-01-01

    The dynamical behavior of vapor ingestion, liquid residual at the incipience of suction dip, liquid hydrogen shut-off at the incipience of suction dip, and slosh wave excitation under normal and various reduced gravity environments and different flow rates of liquid during draining have been investigated. It shows that the liquid residual at the incipience of suction dip increases as the values of gravity environment decrease from normal gravity to lower reduced gravity, and also that the liquid residual increases as the flow rates of liquid increase during the courses of liquid hydrogen draining. It also shows that slosh waves accompanied by strong geyser are developed for surge-related flowfields at the moment of liquid hydrogen shut-off. Slosh wave excitation, during the liquid hydrogen shut-off, shift the fluid mass distribution in the container which imposes time-dependent variation in spacecraft moment of inertia.

  16. Liquid sensor based on a piezoelectric lateral electric field-excited resonator.

    PubMed

    Zaitsev, Boris D; Shikhabudinov, Alexander M; Teplykh, Andrey A; Kuznetsova, Iren E

    2015-12-01

    The influence of viscous and conducting liquid on the characteristics of a piezoelectric lateral electric field-excited resonator based on the X-cut lithium niobate plate has been investigated. It has been found that the contact of a free surface of such resonator with conducting or viscous liquid leads to the substantial variation of its electrical impedance/admittance. The analysis has shown the modulus of electrical impedance or admittance at any frequency near the parallel or series resonance to be a parameter unambiguously associated with the conductivity or the viscosity. This parameter is more sensitive to the variation of the liquid conductivity or viscosity as compared to the widely used for this purpose resonant frequency whose variation area is essentially smaller. By this means the liquid conductivity and viscosity affects unambiguously on the change of electrical impedance and admittance modulus whose measurement at a fixed frequency should present no problem in practice. Consequently, the lateral field excited resonator we have described may be employed as a liquid conductivity and viscosity meter with an appropriate graduation. PMID:26216121

  17. Local liquid crystal alignment on patterned micrograting structures photofabricated by two photon excitation direct laser writing

    NASA Astrophysics Data System (ADS)

    Lee, Chee Heng; Yoshida, Hiroyuki; Miura, Yusuke; Fujii, Akihiko; Ozaki, Masanori

    2008-10-01

    The authors demonstrate local alignment of nematic liquid crystal through the fabrication of local micrograting structures by curing an ultraviolet curable material via a two-photon excitation laser-lithography process. A local twisted-nematic region was prepared using one rubbed and one fabricated micrograting surface and the resulting cell was observed with a polarizing optical microscope. The polarization optical micrographs of the locally fabricated region suggest that liquid crystal molecules align parallel to the grating structure and that local alignment is achieved. We evaluate the anchoring energies of the fabricated microgratings by the torque balance method.

  18. Internal resonance of nonlinear sloshing in rectangular liquid tanks subjected to obliquely horizontal excitation

    NASA Astrophysics Data System (ADS)

    Ikeda, Takashi; Harata, Yuji; Osasa, Takefumi

    2016-01-01

    Nonlinear sloshing in rectangular tanks subjected to obliquely horizontal, harmonic excitation is investigated when the internal resonance condition 1:1 is satisfied between the natural frequencies of predominate modes (1, 0) and (0, 2). Galerkin's method is employed to derive the nonlinear modal equations of motion for sloshing, considering nine sloshing modes. Then, van der Pol's method is applied in order to obtain the expressions of the frequency response curves for amplitudes and phase angles of the predominate modes. The frequency response curves are calculated and reveal that (0, 2) mode may occur even though it is not directly excited because it is nonlinearly coupled with (1, 0) mode due to the autoparametric terms. In the numerical simulations, it is found that planar motions of (1, 0) mode, clockwise and counter-clockwise swirl motions, and translational motions may appear. Furthermore, Hopf bifurcation occurs, and amplitude modulated motions (AMMs), including chaotic motions, may appear depending on the value of the excitation frequency. Three-dimensional distribution charts of the maximum liquid surface elevation are calculated to show the risk of liquid overspill. The influence of the difference between the horizontal excitation direction and the tank side on the frequency response curves is also examined. Bifurcation sets are calculated to clarify this influence. Experimental data confirmed the validity of the theoretical results.

  19. Projectile channeling in chain bundle dusty plasma liquids: Wave excitation and projectile-wave interaction

    SciTech Connect

    Chang, Mei-Chu; Tseng, Yu-Ping; I, Lin

    2011-03-15

    The microscopic channeling dynamics of projectiles in subexcitable chain bundle dusty plasma liquids consisting of long chains of negatively charged dusts suspended in low pressure glow discharges is investigated experimentally using fast video-microscopy. The long distance channeling of the projectile in the channel formed by the surrounding dust chain bundles and the excitation of a narrow wake associated with the elliptical motions of the background dusts are demonstrated. In the high projectile speed regime, the drag force due to wake wave excitation increases with the decreasing projectile speed. The excited wave then leads the slowed down projectile after the projectile speed is decreased below the resonant speed of wave excitation. The wave-projectile interaction causes the increasing projectile drag below the resonant speed and the subsequent oscillation around a descending average level, until the projectile settles down to the equilibrium point. Long distance projectile surfing through the resonant crest trapping by the externally excited large amplitude solitary wave is also demonstrated.

  20. Inelastic electron and Raman scattering from the collective excitations in quantum wires

    NASA Astrophysics Data System (ADS)

    Kushwaha, Manvir

    2014-03-01

    The nanofabrication technology has taught us that an m-dimensional confining potential imposed upon an n-dimensional electron gas paves the way to a quasi-(n- m)-dimensional electron gas, with m <= n and 1 <= n , m <= 3 . This is the road to the (semiconducting) quasi- n dimensional electron gas systems we have been happily traversing on now for almost two decades. Achieving quasi-one dimensional electron gas (Q-1DEG) led us to some mixed moments in this journey: while the reduced phase space for the scattering led us believe in the route to the faster electron devices, the proximity to the 1D systems left us in the dilemma of describing it as a Fermi liquid or as a Luttinger liquid. No one had ever suspected the potential of the former, but it took quite a while for some to convince the others on the latter. A realistic Q-1DEG system at the low temperatures is best describable as a Fermi liquid rather than as a Luttinger liquid. This has motivated us to employ the Bohm-Pines' full RPA to develop a systematic methodology for the inelastic electron and light scattering from the collective (plasmon) excitations in Q-1DEG [or quantum wires]. We will discuss in detail the results published in AIP Advances 3, 042103 (2013).

  1. Evidence of delayed light emission of TetraPhenyl Butadiene excited by liquid Argon scintillation light

    E-print Network

    Ettore Segreto

    2015-03-29

    TetraPhenyl Butadiene is the wavelength shifter most widely used in combination with liquid Argon. The latter emits scintillation photons with a wavelength of 127 nm that need to be downshifted to be detected by photomultipliers with glass or quartz windows. TetraPhenyl Butadiene has been demonstrated to have an extremely high conversion efficiency, possibly higher than 100 % for 127 nm photons, while there is no precise information about the time dependence of its emission. It is usually assumed to be exponentially decaying with a characteristic time of the order of one ns, as an extrapolation from measurements with exciting radiation in the near UV. This work shows that TetraPhenyl Butadiene, when excited by 127 nm photons, reemits photons not only with a very short decay time, but also with slower ones due to triplet states de-excitations. This fact can strongly contribute to clarify the anomalies in liquid Argon scintillation light reported in literature since seventies, namely the inconsistency in the measured values of the long decay time constant and the appearance of an intermediate component. Similar effects should be also expected when the TPB is used in combination with Helium and Neon, that emit scintillation photons with wavelengths shorter than 127 nm.

  2. Luttinger's theorem, superfluid vortices, and holography

    E-print Network

    Nabil Iqbal; Hong Liu

    2012-06-04

    Strongly coupled field theories with gravity duals can be placed at finite density in two ways: electric field flux emanating from behind a horizon, or bulk charged fields outside of the horizon that explicitly source the density. We discuss field-theoretical observables that are sensitive to this distinction. If the charged fields are fermionic, we discuss a modified Luttinger's theorem that holds for holographic systems, in which the sum of boundary theory Fermi surfaces counts only the charge outside of the horizon. If the charged fields are bosonic, we show that the the resulting superfluid phase may be characterized by the coefficient of the transverse Magnus force on a moving superfluid vortex, which again is sensitive only to the charge outside of the horizon. For holographic systems these observables provide a field-theoretical way to distinguish how much charge is held by a dual horizon, but they may be useful in more general contexts as measures of deconfined (i.e. "fractionalized") charge degrees of freedom.

  3. Bose-Einstein Condensation in the Luttinger-Sy Model

    E-print Network

    Olivier Lenoble; Valentin Zagrebnov

    2006-04-27

    We present a rigorous study of the Bose-Einstein condensation in the Luttinger-Sy model. We prove the existence of the condensation in this one-dimensional model of the perfect boson gas placed in the Poisson random potential of singular point impurities. To tackle the off-diagonal long-range order we calculate explicitly the corresponding space-averaged one-body reduced density matrix. We show that mathematical mechanism of the Bose-Einstein condensation in this random model is similar to condensation in a one-dimensional nonrandom hierarchical model of scaled intervals. For the Luttinger-Sy model we prove the Kac-Luttinger conjecture, i.e., that this model manifests a type I BEC localized in a single "largest" interval of logarithmic size.

  4. Shear viscosity in a non-Fermi-liquid phase of a quadratic semimetal

    NASA Astrophysics Data System (ADS)

    Dumitrescu, Philipp T.

    2015-09-01

    We study finite temperature transport in the Luttinger-Abrikosov-Beneslavskii phase—an interacting, scale invariant, non-Fermi-liquid phase found in quadratic semimetals. We develop a kinetic equation formalism to describe the dc transport properties, which are dominated by collisions, and compute the shear viscosity ? . The ratio of shear viscosity to entropy density ? /s is a measure of the strength of interaction between the excitations of a quantum fluid. As a consequence of the quantum critical nature of the system, ? /s is a universal number and we find it to be consistent with a bound proposed from gauge-gravity duality.

  5. Photodissociation of ICN in polar solvents: Evidence for long lived rotational excitation in room temperature liquids

    NASA Astrophysics Data System (ADS)

    Moskun, Amy C.; Bradforth, Stephen E.

    2003-08-01

    Ultrafast polarized pump-probe spectroscopy has been used to study the ICN Ã band photodissociation dynamics in several molecular liquids (water, ethanol, methanol, and chloroform). By exciting at 224 and 255 nm and probing at 385 nm near the gas phase CN B?X transition, the population and vector correlations in the resulting products have been followed with ˜150 fs time resolution. The exhaustive gas-phase reaction dynamics charted for this system indicate that a substantial torque is imparted to the CN fragment in the ground state I dissociation channel while the CN is rotationally cold in the I* channel. The fate of the highly rotationally excited fragment in a liquid environment is explored in the present study. The transient pump-probe anisotropy in ethanol and methanol shows two time scales for decay, ˜400 fs and 3-7 ps depending on excitation energy; the two time scales are assigned to the two product channels. The subpicosecond time scale is characteristic of rotational diffusion of thermalized CN while the longer several picosecond time scale suggests the rotationally hot CN rotate nearly freely for several picoseconds in the plane defined by the initial dissociative event. The rotational behavior of a diatomic fragment is considered between the free rotor and small-angle rotational diffusion limits. The CN photoproduct population dynamics are quite varied in the different solvents. In alcohols and chloroform, CN undergoes abstraction reactions with the solvent while in water there is no abstraction. Caging and diffusive geminate recombination dynamics apparently vary markedly in the different solvents; these effects are compared to molecular dynamics results for this photodissociation system. A large isotope effect is observed between H2O and D2O solvents in the product recombination dynamics.

  6. Quantitative force and dissipation measurements in liquids using piezo-excited atomic force microscopy: a unifying theory.

    PubMed

    Kiracofe, Daniel; Raman, Arvind

    2011-12-01

    The use of a piezoelectric element (acoustic excitation) to vibrate the base of microcantilevers is a popular method for dynamic atomic force microscopy. In air or vacuum, the base motion is so small (relative to tip motion) that it can be neglected. However, in liquid environments the base motion can be large and cannot be neglected. Yet it cannot be directly observed in most AFMs. Therefore, in liquids, quantitative force and energy dissipation spectroscopy with acoustic AFM relies on theoretical formulae and models to estimate the magnitude of the base motion. However, such formulae can be inaccurate due to several effects. For example, a significant component of the piezo excitation does not mechanically excite the cantilever but rather transmits acoustic waves through the surrounding liquid, which in turn indirectly excites the cantilever. Moreover, resonances of the piezo, chip and holder can obscure the true cantilever dynamics even in well-designed liquid cells. Although some groups have tried to overcome these limitations (either by theory modification or better design of piezos and liquid cells), it is generally accepted that acoustic excitation is unsuitable for quantitative force and dissipation spectroscopy in liquids. In this paper the authors present a careful study of the base motion and excitation forces and propose a method by which quantitative analysis is in fact possible, thus opening this popular method for quantitative force and dissipation spectroscopy using dynamic AFM in liquids. This method is validated by experiments in water on mica using a scanning laser Doppler vibrometer, which can measure the actual base motion. Finally, the method is demonstrated by using small-amplitude dynamic AFM to extract the force gradients and dissipation on solvation shells of octamethylcyclotetrasiloxane (OMCTS) molecules on mica. PMID:22071495

  7. Soil-structure interaction effects for laterally excited liquid-tank system

    SciTech Connect

    Tang, Yu ); Veletsos, A.S. . Dept. of Civil Engineering)

    1992-01-01

    Following a brief review of the mechanical model for liquid-storage tanks which permits consideration of the effects of tank and ground flexibility, and lateral and rocking base excitations, the effects of both kinematic and inertia interaction effects on the response of the tank-liquid system are examined and elucidated. The free-field motion is defined by a power spectral density function and an incoherence function, which characterizes the spatial variability of the ground motion due to the vertically incident incoherence waves. The quantities examined are the ensemble means of the peak values of the response. The results are compared with those obtained for no soil-structure interaction and for kinematic interaction to elucidate the nature and relative importance of the two interactions. Only the impulsive actions are examined, the convective actions are for all practical purposes unaffected by both kinematic and inertia interactions. It is shown that the major reduction of the response is attributed to inertia interaction. 20 refs.

  8. Soil-structure interaction effects for laterally excited liquid-tank system

    SciTech Connect

    Tang, Yu; Veletsos, A.S.

    1992-05-01

    Following a brief review of the mechanical model for liquid-storage tanks which permits consideration of the effects of tank and ground flexibility, and lateral and rocking base excitations, the effects of both kinematic and inertia interaction effects on the response of the tank-liquid system are examined and elucidated. The free-field motion is defined by a power spectral density function and an incoherence function, which characterizes the spatial variability of the ground motion due to the vertically incident incoherence waves. The quantities examined are the ensemble means of the peak values of the response. The results are compared with those obtained for no soil-structure interaction and for kinematic interaction to elucidate the nature and relative importance of the two interactions. Only the impulsive actions are examined, the convective actions are for all practical purposes unaffected by both kinematic and inertia interactions. It is shown that the major reduction of the response is attributed to inertia interaction. 20 refs.

  9. Destruction of liquid and gaseous waste surrogates in an acoustically excited dump combustor

    SciTech Connect

    Willis, J.W.; Cadou, C.; Mitchell, M.; Karagozian, A.R.; Smith, O.I. )

    1994-11-01

    Destruction of gaseous and liquid waste surrogates is studied in a two-dimensional dump combustor configuration. Two different waste surrogates are examined: sulfur hexafluoride, which is injected in the gaseous phase and pyrolyzed at high temperatures, and acetonitrile, which is injected in the liquid phase and can be burned in the presence of high concentrations of oxidizing species. Waste surrogates are injected through movable ceramic plugs into the recirculation zones within the dump combustor cavity. The movable plugs allow the combustor cavity length to be altered, in turn exciting or damping various acoustic modes of the device. Strong coupling among the fluid mechanics, acoustics, and combustion/incineration processes are observed in this device; these processes are representative of dump combustors in general. Among the important observations in this study is that waste destruction is strongly affected by the flame and recirculation zone stability. When the flame is perturbed by large vortical structures corresponding to low-frequency chugging'' oscillations, or when it is chaotically destabilized (while acoustically quiet), the recirculation zones into which waste is injected can be destabilized, and DREs for the surrogate are reduced. When the flame is stabilized under conditions which are acoustically quiet, or when the flame is only slightly wrinkled or disturbed, as under high-frequency mode conditions, the recirculation zones are stable and waste is usually destroyed well. Waste destruction itself, however, is also observed to affect recirculation zone and flame stability in addition to affecting the device's acoustic signature.

  10. Nonlinear TeraHertz Coherent Excitation of Vibrational Modes of Liquids

    E-print Network

    Allodi, Marco A; Blake, Geoffrey A

    2015-01-01

    We report the first coherent excitation of intramolecular vibrational modes via the nonlinear interaction of a TeraHertz (THz) light field with molecular liquids. A TeraHertz-TeraHertz-Raman pulse sequence prepares the coherences with a broadband, high-energy, (sub)picosecond TeraHertz pulse, that are then measured in a TeraHertz Kerr effect spectrometer via phase-sensitive, heterodyne detection with an optical pulse. The spectrometer reported here has broader TeraHertz frequency coverage and an increased sensitivity relative to previously reported TeraHertz Kerr effect experiments. Vibrational coherences are observed in liquid diiodomethane at 3.66 THz (122 cm$^{-1}$), and in carbon tetrachloride at 6.50 THz (217 cm$^{-1}$), in exact agreement with literature values of those intramolecular modes. This work opens the door to 2D spectroscopies, nonlinear in TeraHertz field, that can study the dynamics of condensed-phase molecular systems, as well as coherent control at TeraHertz frequencies.

  11. Fractional Wigner Crystal in the Helical Luttinger Liquid.

    PubMed

    Ziani, N Traverso; Crépin, F; Trauzettel, B

    2015-11-13

    The properties of the strongly interacting edge states of two dimensional topological insulators in the presence of two-particle backscattering are investigated. We find an anomalous behavior of the density-density correlation functions, which show oscillations that are neither of Friedel nor of Wigner type: they, instead, represent a Wigner crystal of fermions of fractional charge e/2, with e the electron charge. By studying the Fermi operator, we demonstrate that the state characterized by such fractional oscillations still bears the signatures of spin-momentum locking. Finally, we compare the spin-spin correlation functions and the density-density correlation functions to argue that the fractional Wigner crystal is characterized by a nontrivial spin texture. PMID:26613457

  12. Fractional Wigner Crystal in the Helical Luttinger Liquid

    NASA Astrophysics Data System (ADS)

    Ziani, N. Traverso; Crépin, F.; Trauzettel, B.

    2015-11-01

    The properties of the strongly interacting edge states of two dimensional topological insulators in the presence of two-particle backscattering are investigated. We find an anomalous behavior of the density-density correlation functions, which show oscillations that are neither of Friedel nor of Wigner type: they, instead, represent a Wigner crystal of fermions of fractional charge e /2 , with e the electron charge. By studying the Fermi operator, we demonstrate that the state characterized by such fractional oscillations still bears the signatures of spin-momentum locking. Finally, we compare the spin-spin correlation functions and the density-density correlation functions to argue that the fractional Wigner crystal is characterized by a nontrivial spin texture.

  13. Wentzel-Bardeen singularity in coupled Luttinger liquids: Transport properties

    SciTech Connect

    Martin, T.

    1994-08-26

    The recent progress on 1 D interacting electrons systems and their applications to study the transport properties of quasi one dimensional wires is reviewed. We focus on strongly correlated elections coupled to low energy acoustic phonons in one dimension. The exponents of various response functions are calculated, and their striking sensitivity to the Wentzel-Bardeen singularity is discussed. For the Hubbard model coupled to phonons the equivalent of a phase diagram is established. By increasing the filling factor towards half filling the WB singularity is approached. This in turn suppresses antiferromagnetic fluctuations and drives the system towards the superconducting regime, via a new intermediate (metallic) phase. The implications of this phenomenon on the transport properties of an ideal wire as well as the properties of a wire with weak or strong scattering are analyzed in a perturbative renormalization group calculation. This allows to recover the three regimes predicted from the divergence criteria of the response functions.

  14. Cross sections, stopping powers, and energy loss rates for rotational and phonon excitation processes in liquid water by electron impact

    NASA Astrophysics Data System (ADS)

    Kai, Takeshi; Yokoya, Akinari; Ukai, Masatoshi; Watanabe, Ritsuko

    2015-03-01

    We calculated cross sections, stopping powers, and energy loss rates for rotational and phonon-mode excitations caused by the impact of an electron in an energy region from 0.1 meV to 100 eV injected into liquid water. The spatial distribution of the decelerated electron depends on these cross sections. We performed calculations assuming an optical approximation with the dielectric functions that are experimentally reported in the literature. We observed that the cross sections lie below 1×10-16 cm2 over the considered energy region. The values for rotational excitation processes in the liquid phase are less by three orders of magnitude than those in the gas phase because of the screening effect of neighboring water molecules on the interaction between the incident electron and water molecules. These results suggest that the cross sections in the liquid phase are significantly different from those in the gas phase. The values for phonon-mode excitations in the liquid phase are close to those reported for amorphous ice. Furthermore, we observed that the stopping power shows a maximum around 200 meV, and the energy loss rates, which are derived from the stopping power, depend significantly on the electron energy, particularly below 1 eV. The values obtained here will allow us to precisely estimate the decelerating process of an electron in liquid water to predict radiation effects such as chemical processes in water radiolysis or biomolecular damage induction strongly involved in low energy electron processes.

  15. Effect of killer impurities on laser-excited barium-doped ZnS phosphors at liquid nitrogen temperature

    NASA Astrophysics Data System (ADS)

    Kumar, Sunil; Verma, N. K.; Bhatti, H. S.

    Zinc sulphide phosphors doped with Ba, as well as killer impurities of Fe, Co and Ni, having variable concentrations, were synthesized; and using an ultraviolet laser as the excitation source, decay-curve analyses were done. Various strong emissions in these phosphors were detected and the corresponding excited-state life times were measured at liquid nitrogen temperature. Studies were carried out to see the effect of killer impurities on the phosphorescence excited-state life times. Excited-state life times were found to decrease appreciably (microsecond to nanosecond) with the addition of quenchers. These studies are quite useful and find applications in areas such as optical memories, sensors, luminescent screens, laser-beam detection and alignment, color displays, printing, etc.

  16. Radiation-induced ionization and excitation in liquid p-dioxane

    NASA Astrophysics Data System (ADS)

    Ausloos, P.; Lutz, C.; Schwartz, F.; Lias, S. G.

    The fluorescence of neat liquid p-dioxane and p-dioxane-water mixtures has been studied as a function of wavelength in the range 200-110 nm, and in the system under beta irradiation. It is seen that the quantum yield of fluorescence declines from the absorption threshold to the ionization onset (˜ 160-170 nm), because of the increasing importance of the competing decomposition processes. Above the ionization onset, there is a slight increase in the quantum yield of fluorescence as a result of the occurrence of "recombination fluorescence". However, it is estimated that in this region, neutralization does not always lead to a vibrationally equilibrated excited state. This explains in part why the G-value of thermally equilibrated S1 states is considerably lower than G(ion)(˜5), under conditions that fluorescence originates mainly from charge recombination. Auxiliary experiments carried out in the gas phase, in an ion cyclotron resonance spectrometer, elucidated the reaction of p-C 4H 8O 2+ ions with p-dioxane molecules. The results indicate that in the gas phase, proton transfer between these reactants is thermoneutral, and occurs with a lowered efficiency (i.e. does not occur at every collision) in contrast with m-dioxane for which the corresponding proton transfer reaction is highly exothermic and kRn = kCollision. In the liquid phase, proton transfer is unimportant in the p-dioxane system, but probably is the predominant fate of the m-C 4H 8O 2+ ion in m-dioxane. The well known shift of emission to lower energies in p-dioxane-water mixtures has been examined; the shift depends only on the concentration of water, and not on the type or energy of the radiation. In the presence of added 1-methylnaphthalene, it is seen that there is no change in the quantum yield of emission from methylnaphthalene at energies below the ionization onset, but that there is a decrease in the fluorescence yield with increasing water concentration above the ionization threshold. In p-dioxane: H 2O: toluene mixtures, on the other hand, the toluene fluorescence diminishes with increasing water concentration at all energies. These observations are interpreted in terms of changes in the energy level of the electronically-excited p-dioxane-water aggregate and on proton transfer reactions involving dioxane-water aggregates.

  17. Photothermal excitation and laser Doppler velocimetry of higher cantilever vibration modes for dynamic atomic force microscopy in liquid

    SciTech Connect

    Nishida, Shuhei; Kobayashi, Dai; Sakurada, Takeo; Nakazawa, Tomonori; Hoshi, Yasuo; Kawakatsu, Hideki

    2008-12-15

    The authors present an optically based method combining photothermal excitation and laser Doppler velocimetry of higher cantilever vibration modes for dynamic atomic force microscopy in liquid. The frequency spectrum of a silicon cantilever measured in water over frequencies ranging up to 10 MHz shows that the method allows us to excite and detect higher modes, from fundamental to fifth flexural, without enhancing spurious resonances. By reducing the tip oscillation amplitude using higher modes, the average tip-sample force gradient due to chemical bonds is effectively increased to achieve high-spatial-resolution imaging in liquid. The method's performance is demonstrated by atomic resolution imaging of a mica surface in water obtained using the second flexural mode with a small tip amplitude of 99 pm; individual atoms on the surface with small height differences of up to 60 pm are clearly resolved.

  18. An atmospheric air gas-liquid diffuse discharge excited by bipolar nanosecond pulse in quartz container used for water sterilization

    NASA Astrophysics Data System (ADS)

    Wang, Sen; Yang, De-Zheng; Wang, Wen-Chun; Zhang, Shuai; Liu, Zhi-Jie; Tang, Kai; Song, Ying

    2013-12-01

    In this Letter, we report that the air gas-liquid diffuse discharge plasma excited by bipolar nanosecond pulse in quartz container with different bottom structures at atmospheric pressure. Optical diagnostic measurements show that bountiful chemically and biologically active species, which are beneficial for effective sterilization in some areas, are produced. Such diffuse plasmas are then used to treat drinking water containing the common microorganisms (Candida albicans and Escherichia coli). It is found that these plasmas can sterilize the microorganisms efficiently.

  19. Sloshing response of nonuniform density liquid in a laterally excited tank

    SciTech Connect

    Tang, Y.; Chang, Y.W.

    1993-10-01

    A large number of high level waste (HLW) storage tanks at various facilities contain liquid with nonuniformity density. Exploratory studies show that the dynamic response of a tank containing two liquids is quite different from that of an identical tank containing only one liquid. To design and evaluate the HLW storage tanks it is necessary to understand the sloshing response of tanks that contain liquid with nonuniform density. The system considered is a circular cylindrical tank containing a liquid whose density increases with the liquid depth. The density distribution along the depth can be of any arbitrary continuous function. In the analysis, the liquid field is divided into n layers. The thicknesses of the liquid layers can be different, but the density of each liquid layer is considered to be uniform and its value is assigned to be the value of the original liquid density at the mid-height of that layer. The problem is solved by the transfer matrix technique. The effect of the nonuniform liquid density on the sloshing response is illustrated in a numerical example in which the linear and cosine distributions of the liquid density are assumed. The response functions examined include the sloshing frequencies, surface wave height, and the associated convective hydrodynamic pressure. The results are presented in tabular and graphical forms. It is found that the natural frequencies of the sloshing motion for nonuniform density liquid are lower than those of the uniform density liquid of the same total depth contained in an identical tank. Also, it is shown that for nonuniform density liquid, the maximum sloshing wave height may increase significantly and the magnitude of the convective hydrodynamic pressure may be quite different compared with that of a uniform liquid contained in an identical tank.

  20. Cryogenic exciter

    SciTech Connect

    Bray, James William; Garces, Luis Jose

    2012-03-13

    The disclosed technology is a cryogenic static exciter. The cryogenic static exciter is connected to a synchronous electric machine that has a field winding. The synchronous electric machine is cooled via a refrigerator or cryogen like liquid nitrogen. The static exciter is in communication with the field winding and is operating at ambient temperature. The static exciter receives cooling from a refrigerator or cryogen source, which may also service the synchronous machine, to selected areas of the static exciter and the cooling selectively reduces the operating temperature of the selected areas of the static exciter.

  1. X-ray study of the liquid potassium surface: Structure and capillary wave excitations Oleg Shpyrko, Patrick Huber, Alexei Grigoriev, and Peter Pershan

    E-print Network

    Pershan, Peter S.

    X-ray study of the liquid potassium surface: Structure and capillary wave excitations Oleg Shpyrko the liquid surface of pure potassium. They strongly suggest the existence of atomic layering at the free that of potassium, and hence closer to inducing an ideal ``hard wall'' boundary condition. The experimental result

  2. YIELDS OF IONS AND EXCITED STATES IN NONPOLAR LIQUIDS EXPOSED TO X-RAYS OF 1 TO 30 KEV ENERGY

    SciTech Connect

    HOLROYD,R.A.

    1999-08-18

    When x-rays from a synchrotron source are absorbed in a liquid, the x-ray energy (E{sub x}) is converted by the photoelectric effect into the kinetic energy of the electrons released. For hydrocarbons, absorption by the K-electrons of carbon dominates. Thus the energy of the photoelectron (E{sub pe}) is E{sub x}-E{sub b}, where E{sub b} is the K-shell binding energy of carbon. Additional electrons with energy equal to E{sub b} is released in the Auger process that fills the hole in the K-shell. These energetic electrons will produce many ionizations, excitations and products. The consequences of the high density of ionizations and excitations along the track of the photoelectron and special effects near the K-edge are examined here.

  3. Focus: Phase-resolved nonlinear terahertz spectroscopy--From charge dynamics in solids to molecular excitations in liquids.

    PubMed

    Elsaesser, Thomas; Reimann, Klaus; Woerner, Michael

    2015-06-01

    Intense terahertz (THz) electric field transients with amplitudes up to several megavolts/centimeter and novel multidimensional techniques are the key ingredients of nonlinear THz spectroscopy, a new area of basic research. Both nonlinear light-matter interactions including the non-perturbative regime and THz driven charge transport give new insight into the character and dynamics of low-energy excitations of condensed matter and into quantum kinetic phenomena. This article provides an overview of recent progress in this field, combining an account of technological developments with selected prototype results for liquids and solids. The potential of nonlinear THz methods for future studies of low-frequency excitations of condensed-phase molecular systems is discussed as well. PMID:26049419

  4. According to Landau's Fermi liquid theory1 , a bulk metallic system of

    E-print Network

    Johannesson, Henrik

    According to Landau's Fermi liquid theory1 , a bulk metallic system of interacting electrons has to behave in a highly cooperative way, and the Fermi liquid theory no longer applies. Progress in obtaining­electron interactions. From Fermi liquids to Luttinger liquids Coulomb forces acting between electrons and ions hold

  5. Determination of leucomalachite green, leucocrystal violet and their chromic forms using excitation-emission matrix fluorescence coupled with second-order calibration after dispersive liquid-liquid microextraction.

    PubMed

    Ju, Saiqin; Deng, Jian; Cheng, Jianlin; Xiao, Ni; Huang, Kaihui; Hu, Canhui; Zhao, Haiqing; Xie, Jin; Zhan, Xiaozhu

    2015-10-15

    A novel spectrofluorimetric method has been developed for the simultaneous determination of leucomalachite green (LMG), leucocrystal violet (LCV), malachite green (MG) and crystal violet (CV) by combining the sensitivity of molecular fluorescence and the selectivity of the second-order calibration. Residues of LMG, LCV, MG and CV were simultaneously extracted from fish and shrimp muscle with acetonitrile. The non-fluorescent CV and MG were then reduced to the corresponding fluorescent LMG and LCV by reacting with sodium borohydride. After preconcentration with dispersive liquid-liquid microextraction technique, the extracts were analyzed by using excitation-emission matrix fluorescence coupled with second-order calibration methods based on parallel factor analysis (PARAFAC) and alternating trilinear decomposition (ATLD) algorithms. The limits of detection obtained were 2.21-2.65 ng g(-1) by PARAFAC and 2.30-2.86 ng g(-1) by ATLD, respectively. The developed method was successfully applied to simultaneous determination of the four analytes in grass carp and shrimp samples with recoveries of 90.53-103.03% for PARAFAC and 90.40-102.75% for ATLD. The accuracy of this novel method was also verified by high performance liquid chromatography. PMID:25952896

  6. Correcting spherical aberrations in a biospecimen using a transmissive liquid crystal device in two-photon excitation laser scanning microscopy.

    PubMed

    Tanabe, Ayano; Hibi, Terumasa; Ipponjima, Sari; Matsumoto, Kenji; Yokoyama, Masafumi; Kurihara, Makoto; Hashimoto, Nobuyuki; Nemoto, Tomomi

    2015-10-01

    Two-photon excitation laser scanning microscopy has enabled the visualization of deep regions in a biospecimen. However, refractive-index mismatches in the optical path cause spherical aberrations that degrade spatial resolution and the fluorescence signal, especially during observation at deeper regions. Recently, we developed transmissive liquid-crystal devices for correcting spherical aberration without changing the basic design of the optical path in a conventional laser scanning microscope. In this study, the device was inserted in front of the objective lens and supplied with the appropriate voltage according to the observation depth. First, we evaluated the device by observing fluorescent beads in single- and two-photon excitation laser scanning microscopes. Using a 25× water-immersion objective lens with a numerical aperture of 1.1 and a sample with a refractive index of 1.38, the device recovered the spatial resolution and the fluorescence signal degraded within a depth of 0.6 mm. Finally, we implemented the device for observation of a mouse brain slice in a two-photon excitation laser scanning microscope. An optical clearing reagent with a refractive index of 1.42 rendered the fixed mouse brain transparent. The device improved the spatial resolution and the yellow fluorescent protein signal within a depth of 0-0.54 mm. PMID:26244766

  7. Correcting spherical aberrations in a biospecimen using a transmissive liquid crystal device in two-photon excitation laser scanning microscopy

    NASA Astrophysics Data System (ADS)

    Tanabe, Ayano; Hibi, Terumasa; Ipponjima, Sari; Matsumoto, Kenji; Yokoyama, Masafumi; Kurihara, Makoto; Hashimoto, Nobuyuki; Nemoto, Tomomi

    2015-08-01

    Two-photon excitation laser scanning microscopy has enabled the visualization of deep regions in a biospecimen. However, refractive-index mismatches in the optical path cause spherical aberrations that degrade spatial resolution and the fluorescence signal, especially during observation at deeper regions. Recently, we developed transmissive liquid-crystal devices for correcting spherical aberration without changing the basic design of the optical path in a conventional laser scanning microscope. In this study, the device was inserted in front of the objective lens and supplied with the appropriate voltage according to the observation depth. First, we evaluated the device by observing fluorescent beads in single- and two-photon excitation laser scanning microscopes. Using a 25× water-immersion objective lens with a numerical aperture of 1.1 and a sample with a refractive index of 1.38, the device recovered the spatial resolution and the fluorescence signal degraded within a depth of ±0.6 mm. Finally, we implemented the device for observation of a mouse brain slice in a two-photon excitation laser scanning microscope. An optical clearing reagent with a refractive index of 1.42 rendered the fixed mouse brain transparent. The device improved the spatial resolution and the yellow fluorescent protein signal within a depth of 0-0.54 mm.

  8. Atypical energetic and kinetic course of excited-state intramolecular proton transfer (ESIPT) in room-temperature protic ionic liquids.

    PubMed

    Manna, Arpan; Sayed, Mhejabeen; Kumar, Anil; Pal, Haridas

    2014-03-01

    The excited-state intramolecular proton-transfer (ESIPT) process in 1,8-dihydroxyanthraquinone (18DHAQ) dye has been investigated in protic ionic liquid (PIL) solvents using photochemical measurements. The results demonstrate noteworthy modulations in both steady-state and time-resolved emission characteristics of excited normal (N*) and tautomeric (T*) forms of the dye. That the emission of T* increases unexpectedly upon increasing solvent viscosity indicates that subsequent to the initial forward ESIPT, there is also a relatively slower back ESIPT process involved for the excited dye. It is inferred that the propensity of this back ESIPT process is determined by the dynamics of the diffusive solvent relaxation, a process that is known to be strongly viscosity-dependent in ionic liquids. Evidence of both forward and back ESIPT for the dye has been obtained from femtosecond fluorescence up-conversion measurements. While an unusually fast forward ESIPT is clearly observed in all of the PILs studied, the uncommon back ESIPT process is distinctly indicated in PIL solvents having lower viscosities, certainly due to reasonably fast diffusive solvent relaxation in these solvents that causes a temporal modulation in the energies of the normal and tautomeric forms within a reasonably short time and thereby brings down the energy of N* compared to that of T*, triggering the back ESIPT process. Observation of solvent-viscosity-dependent back ESIPT is an intriguing finding for the present study as to the best of our knowledge, such a behavior has so far not been reported in the literature for the ESIPT reaction. PMID:24524653

  9. Thermally excited capillary waves at vapor/liquid interfaces of water-alcohol mixtures

    NASA Astrophysics Data System (ADS)

    Vaknin, David; Bu, Wei; Sung, Jaeho; Jeon, Yoonnam; Kim, Doseok

    2009-03-01

    The density profiles of liquid/vapor interfaces of water-alcohol (methanol, ethanol and propanol) mixtures were studied by surface-sensitive synchrotron x-ray scattering techniques. X-ray reflectivity and diffuse scattering measurements, from the pure and mixed liquids, were analyzed in the framework of capillary wave theory to address the characteristic length scales of the intrinsic roughness and the shortest capillary wavelength (alternatively, the upper wavevector cutoff in capillary wave theory). Our results establish that the intrinsic roughness is dominated by average interatomic distances. The extracted effective upper wavevector cutoff indicates capillary wave theory breaks down at distances of the order of bulk correlation lengths.

  10. Thermally excited capillary waves at vapor/liquid interfaces of water-alcohol mixtures

    E-print Network

    David Vaknin; Wei Bu; Jaeho Sung; Yoonnam Jeon; Doseok Kim

    2009-04-15

    The density profiles of liquid/vapor interfaces of water-alcohol (methanol, ethanol and propanol) mixtures were studied by surface sensitive synchrotron X-ray scattering techniques. X-ray reflectivity and diffuse scattering measurements, from the pure and mixed liquids, were analyzed in the framework of capillary-wave theory to address the characteristics length-scales of the intrinsic roughness and the shortest capillary-wavelength (alternatively, the upper wave-vector cutoff in capillary wave theory). Our results establish that the intrinsic roughness is dominated by average interatomic distances. The extracted effective upper wave-vector cutoff indicates capillary wave theory breaks-down at distances on order of bulk correlation lengths.

  11. The {alpha}-particle excited scintillation response of the liquid phase epitaxy grown LuAG:Ce thin films

    SciTech Connect

    Prusa, P.; Cechak, T.; Mares, J. A.; Nikl, M.; Beitlerova, A.; Solovieva, N.; Zorenko, Yu. V.; Gorbenko, V. I.; Tous, J.; Blazek, K.

    2008-01-28

    Liquid phase epitaxy grown Lu{sub 3}Al{sub 5}O{sub 12}:Ce (LuAG:Ce) 20 {mu}m thick films and plate cut from the bulk Czochralski-grown LuAG:Ce crystal were prepared for comparison of photoelectron yield (PhY) and PhY dependence on shaping time (0.5-10 {mu}s). {sup 241}Am ({alpha} particles) was used for excitation. At the 0.5 {mu}s shaping time, the best film shows comparable PhY with the bulk sample. PhY of bulk material increases noticeably more with shaping time than that of the films. Energy resolution of films is better. Influence of Pb{sup 2+} contamination in the films (from the flux) and antisite Lu{sub Al} defect in bulk material is discussed.

  12. Effect of the Bethe surface description on the electronic excitations induced by energetic proton beams in liquid water and DNA

    NASA Astrophysics Data System (ADS)

    Abril, Isabel; Denton, Cristian D.; de Vera, Pablo; Kyriakou, Ioanna; Emfietzoglou, Dimitris; Garcia-Molina, Rafael

    2010-06-01

    The irradiation of biological systems by energetic ion beams has multiple applications in medical physics and space radiation health, such as hadrontherapy for cancer treatment or protection of astronauts against space radiation. Therefore, for a better control and understanding of the effects of radiation damage in living tissues, it is necessary to advance an accurate description of the energy loss from the ion beam to the target. In the present work we use the dielectric formalism to calculate the probability for an energetic proton to produce electronic excitations in two targets of high biological interest, namely, liquid water and DNA. Also, the mean energy of the electronic excitations in these targets is found as a function of the incident proton energy. The electronic response of the target, characterized by its energy-loss function (ELF), is described by several models that fit the available experimental optical data (at zero momentum transfer), but use different approaches to obtain the Bethe surface, that is, to extend the ELF to any energy and momentum transferred.

  13. Photo-excited states in germanium at liquid-helium temperatures

    SciTech Connect

    Culbertson, J.C.

    1982-12-01

    A wide variety of experimental work dealing with the basic properties of photoexcited states in Ge at liquid helium temperatures is presented. The primary emphasis is on the electron-hole liquid (EHL) and the free exciton (FE). The EHL is composed of two interpenetrating Fermi liquids, one of electrons and one of holes, each with its own Fermi level. The FE dealt with here is a mobile, loosely bound state of an electron and a hole. We report the first absolute measurement of the density dependence of the enhancement factor g/sub eh/(0) for the EHL in Ge. This factor g/sub eh/(0) is a measure of the electron-hole spatial correlation function, and provides a valuable and sensitive test for the predictions of various many-body-theory approximations. An EHL droplet - FE gas system confined to a strain induced potential well was used. The measurement approach relied on only a few simple and verifiable assumptions. A byproduct of this work was the measurement as a function of stress of: the electron and hole Fermi levels E/sub F//sup e/ and E/sub F//sup h/, the EHL density n/sub l/, the condensation energy phi of a FE relative to the EHL, and the binding energy of a FE (E/sub x/) relative to free carriers (FC). The decay of a FE-FC system confined to a strain induced potential well is studied. The first direct measurement of the FE diffusivity D/sub x/ is reported. The evolution in time of spatial profiles of FE luminescence were measured. From these FE density profiles, D/sub x/(4.2K) approx. = to 300 cm/sup 2/ s/sup -1/, the surface recombination velocity S approx. = 3000 cm s/sup -1/, and the FE lifetime tau/sub x/ = 27 ..mu..s with surface effects excluded were determined. (WHK)

  14. Electronic excited states as a probe of surface adsorbate structure and dynamics in liquid xenon

    SciTech Connect

    Peterson, E.S.

    1992-08-01

    A combination of second harmonic generation (SHG) and a simple dipole-dipole interaction model is presented as a new technique for determining adsorbate geometries on surfaces. The polarization dependence of SHG is used to define possible geometries of the adsorbate about the surface normal. Absorption band shifts using geometry constraints imposed by SHG data are derived for a dimer constructed from two arbitrarily placed monomers on the surface using the dipole-dipole interaction potential. These formulae can be used to determine the orientation of the two monomers relative to each other. A simplified version of this formalism is used to interpret absorption band shifts for rhodamine B adsorbed on fused silica. A brief history of the exciton is given with particular detail to Xe. Data are presented for transient absorption at RT in liquid xenon on the picosecond time scale. These are observations of both tunneling through the barrier that separates the free and trapped exciton states and the subsequent trapping of the exciton. In high densities both of these processes are found to occur within 2 to 6 picoseconds in agreement with theories of Kmiecik and Schreiber and of Martin. A threshold density is observed that separates relaxation via single binary collisions and relaxation that proceeds via Martin's resonant energy transfer hopping mechanism.

  15. Electronic excited states as a probe of surface adsorbate structure and dynamics in liquid xenon

    SciTech Connect

    Peterson, E.S.

    1992-08-01

    A combination of second harmonic generation (SHG) and a simple dipole-dipole interaction model is presented as a new technique for determining adsorbate geometries on surfaces. The polarization dependence of SHG is used to define possible geometries of the adsorbate about the surface normal. Absorption band shifts using geometry constraints imposed by SHG data are derived for a dimer constructed from two arbitrarily placed monomers on the surface using the dipole-dipole interaction potential. These formulae can be used to determine the orientation of the two monomers relative to each other. A simplified version of this formalism is used to interpret absorption band shifts for rhodamine B adsorbed on fused silica. A brief history of the exciton is given with particular detail to Xe. Data are presented for transient absorption at RT in liquid xenon on the picosecond time scale. These are observations of both tunneling through the barrier that separates the free and trapped exciton states and the subsequent trapping of the exciton. In high densities both of these processes are found to occur within 2 to 6 picoseconds in agreement with theories of Kmiecik and Schreiber and of Martin. A threshold density is observed that separates relaxation via single binary collisions and relaxation that proceeds via Martin`s resonant energy transfer hopping mechanism.

  16. Superdeformed nuclei: Shells-vs-liquid drop, pairing-vs-thermal excitations, triaxial-vs-octupole shapes, super-superdeformation

    SciTech Connect

    Dudek, J.

    1987-01-01

    Mechanisms influencing the behavior of superdeformed nuclei are studied using several well established nuclear structure techniques. In particular: pairing, thermal excitation, shell and liquid-drop mechanisms are considered. The effects of quadrupole and hexadecapole (both axial and non-axial), and octupole deformation degrees of freedom are studied. Most of the results are illustrated using the case of /sup 152/Dy nucleus in which a superdeformed band extending up to I approx. 60 h-bar has been found in experiment. Some comparisons between /sup 152/Dy and the nuclei in the neighborhood are given. Calculations show that pairing ''de-aligns'' typically 6 to 8 units of angular momentum, as compared to the corresponding rigid rotation. This takes place for spins extending up to the highest limit, and thus diminishes the effective moments of inertia. Predicted octupole shape susceptibility is extremely large, significantly stronger than the susceptibilities known in the ground-states of many Actinide nuclei. Consequences of this result for the near-constancy of the dynamical moments of inertia are pointed out. Nuclear level densities calculated in function of spin, excitation energy and deformation explain the ''unusual'' side feeding pattern of the /sup 152/Dy superdeformed states. Predictions of super-superdeformed nuclear states (axis ratio varying between 2:1 and 3:1 or more) are given and exemplified for Erbium nuclei. Finally, the problem of superdeformation stability and the influence of increased collective inertia on a barrier penetration are examined. An analytical expression for the effective inertia parameter is obtained and its derivation outlined. 35 refs., 9 figs.

  17. Excitations of nanoscale quantum liquids under pressure and the Bose glass phase Jacques Bossy,1 Jonathan V. Pearce,2,3,* Helmut Schober,3 and Henry R. Glyde2

    E-print Network

    Glyde, Henry R.

    in bulk liquid helium at low temperature is predicted to decrease significantly with in- creasing pressureExcitations of nanoscale quantum liquids under pressure and the Bose glass phase Jacques Bossy,1 of liquid helium confined to nanoscales in 25 and 34 Å mean pore diameter porous media over a range

  18. Quantum oscillations in the Luttinger model with quadratic band touching: Applications to pyrochlore iridates

    NASA Astrophysics Data System (ADS)

    Rhim, Jun-Won; Kim, Yong Baek

    2015-03-01

    Motivated by recent experiments on Pr2Ir2O7 , we provide a theory of quantum oscillations in the Luttinger model with quadratic band touching, modeled for the spin-orbit-coupled conduction electrons in pyrochlore iridates. The magneto- and Hall resistivities are computed for electron- and hole-doped systems, and the corresponding Shubnikov-de Haas (SdH) signals are investigated. The SdH signals are characterized by aperiodic behaviors that originate from the unconventional Landau level structures of the Luttinger model near the neutrality point, such as inter-Landau-level crossing, nonuniform Landau level spacings, and nonparabolic dispersions along the applied magnetic-field direction. The aperiodic SdH signals observed in the paramagnetic state of Pr2Ir2O7 are shown to be consistent with such behaviors, justifying the use of the Luttinger model and the quadratic band touching spectrum as excellent starting points for physics of pyrochlore iridates. The implications of these results are discussed in light of recent theoretical and experimental developments in these systems.

  19. Excited-state relaxation of hydrated thymine and thymidine measured by liquid-jet photoelectron spectroscopy: experiment and simulation.

    PubMed

    Buchner, Franziska; Nakayama, Akira; Yamazaki, Shohei; Ritze, Hans-Hermann; Lübcke, Andrea

    2015-03-01

    Time-resolved photoelectron spectroscopy is performed on thymine and thymidine in aqueous solution to study the excited-state relaxation dynamics of these molecules. We find two contributions with sub-ps lifetimes in line with recent excited-state QM/MM molecular dynamics simulations (J. Chem. Phys. 2013, 139, 214304). The temporal evolution of ionization energies for the excited ??* state along the QM/MM molecular dynamics trajectories were calculated and are compatible with experimental results, where the two contributions correspond to the relaxation paths in the ??* state involving different conical intersections with the ground state. Theoretical calculations also show that ionization from the n?* state is possible at the given photon energies, but we have not found any experimental indication for signal from the n?* state. In contrast to currently accepted relaxation mechanisms, we suggest that the n?* state is not involved in the relaxation process of thymine in aqueous solution. PMID:25671554

  20. Non-Fermi Liquid Behavior in Quasi-One-Dimensional Li0.9Mo6O17

    SciTech Connect

    Hager, J.; Matzdorf, R.; He, Jian; Jin, Rongying; Mandrus, David; Cazalilla, M.; Plummer, E Ward

    2005-01-01

    We present temperature dependent scanning tunneling spectroscopy data of the quasi-one-dimensional conductor Li{sub 0.9}Mo{sub 6}O{sub 17}. The differential tunneling current in our low-temperature spectra shows a power-law behavior around the Fermi energy, which is expected for a clean Luttinger liquid. The power-law exponent is found to be 0.6. Spectra for a temperature range of 5 to 55 K can be fitted fairly well with a model for tunneling into a Luttinger liquid at the appropriate temperature. A fit with a model based on a zero bias anomaly is significantly worse compared to the Luttinger liquid model. No signature of a phase transition at T = 24 K is observed in our temperature dependent data.

  1. On the Luttinger theorem concerning number of particles in the ground states of systems of interacting fermions

    E-print Network

    Behnam Farid

    2007-11-06

    We analyze the original proof by Luttinger and Ward of the Luttinger theorem, according to which for uniform ground states of systems of (interacting) fermions, which may be metallic or insulating, the number of k points corresponding to non-negative values of G_s(k;mu) is equal to the total number of particles with spin index s in these ground states. Here G_s(k;mu) is the single-particle Green function of particles with spin index s at the chemical potential mu. For the cases where the two-body interaction potential is short-range, and in particular for lattice models, we explicitly demonstrate that this theorem is unconditionally valid, irrespective of the strength of the bare interaction potential. We arrive at this conclusion by amongst other things demonstrating that the perturbation series expansion for self-energy in terms of skeleton diagrams, as encountered in the proof of the Luttinger-Ward identity, is uniformly convergent for almost all momenta and energies. We further investigate the mechanisms underlying some reported instances of failure of the Luttinger theorem. With one exception, for all the cases considered in this paper, we show that the apparent failures of the Luttinger theorem can be attributed either to shortcomings of the employed single-particle Green functions or to misapplication of this theorem. The one exceptional case brings to light the possibility of a genuine failure of the Luttinger theorem for insulating ground states, which we show to be brought about by a false limit that in principle can be reached on taking the zero-temperature limit without the value of mu coinciding with the zero-temperature limit of the chemical potential satisfying the equation of state at finite temperatures; no such ambiguity can arise for metallic states.

  2. Universal topological data for gapped quantum liquids in three dimensions and fusion algebra for non-Abelian string excitations

    NASA Astrophysics Data System (ADS)

    Moradi, Heidar; Wen, Xiao-Gang

    2015-02-01

    Recently we conjectured that a certain set of universal topological quantities characterize topological order in any dimension. Those quantities can be extracted from the universal overlap of the ground-state wave functions. For systems with gapped boundaries, these quantities are representations of the mapping class group MCG (M ) of the space manifold M on which the systems live. We will here consider simple examples in three dimensions and give physical interpretation of these quantities, related to the fusion algebra and statistics of particles and string excitations. In particular, we will consider dimensional reduction from 3+1D to 2+1D, and show how the induced 2+1D topological data contain information on the fusion and the braiding of non-Abelian string excitations in 3D. These universal quantities generalize the well-known modular S and T matrices to any dimension.

  3. Mobile impurities in ferromagnetic liquids

    NASA Astrophysics Data System (ADS)

    Kantian, Adrian; Schollwoeck, Ulrich; Giamarchi, Thierry

    2011-03-01

    Recent work has shown that mobile impurities in one dimensional interacting systems may exhibit behaviour that differs strongly from that predicted by standard Tomonaga-Luttinger liquid theory, with the appearance of power-law divergences in the spectral function signifying sublinear diffusion of the impurity. Using time-dependent matrix product states, we investigate a range of cases of mobile impurities in systems beyond the analytically accessible examples to assess the existence of a new universality class of low-energy physics in one-dimensional systems. Correspondence: Adrian.Kantian@unige.ch This work was supported in part by the Swiss SNF under MaNEP and division II.

  4. Optical and application study of gas-liquid discharge excited by bipolar nanosecond pulse in atmospheric air.

    PubMed

    Wang, Sen; Wang, Wen-chun; Yang, De-zheng; Liu, Zhi-jie; Zhang, Shuai

    2014-10-15

    In this study, a bipolar nanosecond pulse with 20ns rising time is employed to generate air gas-liquid diffuse discharge plasma with room gas temperature in quartz tube at atmospheric pressure. The image of the discharge and optical emission spectra of active species in the plasma are recorded. The plasma gas temperature is determined to be approximately 390K by compared the experimental spectra with the simulated spectra, which is slightly higher than the room temperature. The result indicated that the gas temperature rises gradually with pulse peak voltage increasing, while decreases slightly with the electrode gap distance increasing. As an important application, bipolar nanosecond pulse discharge is used to sterilize the common microorganisms (Actinomycetes, Candida albicans and Escherichia coli) existing in drinking water, which performs high sterilization efficiency. PMID:24845733

  5. Optical and application study of gas-liquid discharge excited by bipolar nanosecond pulse in atmospheric air

    NASA Astrophysics Data System (ADS)

    Wang, Sen; Wang, Wen-chun; Yang, De-zheng; Liu, Zhi-jie; Zhang, Shuai

    2014-10-01

    In this study, a bipolar nanosecond pulse with 20 ns rising time is employed to generate air gas-liquid diffuse discharge plasma with room gas temperature in quartz tube at atmospheric pressure. The image of the discharge and optical emission spectra of active species in the plasma are recorded. The plasma gas temperature is determined to be approximately 390 K by compared the experimental spectra with the simulated spectra, which is slightly higher than the room temperature. The result indicated that the gas temperature rises gradually with pulse peak voltage increasing, while decreases slightly with the electrode gap distance increasing. As an important application, bipolar nanosecond pulse discharge is used to sterilize the common microorganisms (Actinomycetes, Candida albicans and Escherichia coli) existing in drinking water, which performs high sterilization efficiency.

  6. On the Luttinger theorem concerning number of particles in the ground states of systems of interacting fermions

    E-print Network

    Farid, Behnam

    2011-01-01

    We analyze the original proof by Luttinger and Ward of the Luttinger theorem, according to which for uniform ground states of systems of (interacting) fermions, which may be metallic or insulating, the number of k points corresponding to non-negative values of G_s(k;mu) is equal to the total number of particles with spin index s in these ground states. Here G_s(k;mu) is the single-particle Green function of particles with spin index s at the chemical potential mu. For the cases where the two-body interaction potential is short-range, and in particular for lattice models, we explicitly demonstrate that this theorem is unconditionally valid, irrespective of the strength of the bare interaction potential. We arrive at this conclusion by amongst other things demonstrating that the perturbation series expansion for self-energy in terms of skeleton diagrams, as encountered in the proof of the Luttinger-Ward identity, is uniformly convergent for almost all momenta and energies. We further investigate the mechanisms ...

  7. Antiferromagnetic marginal Fermi liquid

    SciTech Connect

    Zimanyi, G.T. ); Bedell, K.S. )

    1993-09-01

    The infrared singularities of the marginal-Fermi-liquid theory are treated within a perturbative renormalization-group approach for the original, weakly-momentum-dependent model. Then an alternative framework is introduced: marginal Fermi liquids with strong antiferromagnetic fluctuations. The models in both cases are found to be stable in a limited range of parameters, otherwise non-Fermi-liquid behavior is obtained. Comparison with experiments on the conductivity and spin susceptibility yields quite reasonable agreement between theory and the data in the case of the antiferromagnetic formulation. Trends with the doping and differences between copper and oxygen relaxation rates also gain a natural explanation. Analogies with the Luttinger-liquid ideas are also explored. Finally the antiferromagnetic marginal Fermi liquid offers clues about the microscopic origin of the anomalous fluctuations as well, as we find that the antiferromagnetic model is the [ital minimal] [ital model] capable of supporting a fixed line of the scaling equations, making it a promising candidate for the microscopic foundation of high-temperature superconductivity.

  8. Towards an easy-to-use tuberculosis diagnosis through exhaled breath analysis: a liquid fluorimeter with an excitation at 265 nm

    NASA Astrophysics Data System (ADS)

    Hue, J.; Dupoy, M.; Vignoud, S.; Ricaud, J. L.; Tran-Thi, T.; Karpe, S.; Novelli-Rousseau, A.; Mallard, F.

    2013-03-01

    The struggle against tuberculosis is one of the World Health Organization priorities. Identifying in a short time, patients with active tuberculosis, would bring a tremendous improvement to the current situation. Recovering from this infectious and deadly disease (2 million of death per year) is possible with a correct diagnosis to give an appropriate treatment. Unfortunately, most common tuberculosis diagnoses have few drawbacks: - skin tests: not reliable at 100% and need an incubation of 2 days before the diagnosis, - blood tests: costly and sophisticated technology, - chest X-ray: the first step before the sputum tests used for a bacterial culture with a final diagnosis given within 2 weeks. A tuberculosis test based on exhaled breath analysis is a prospective and noninvasive solution, cheap and easy to use and to transport. This test lies on a fluoregenic detection of niacin, a well-known mycobacterium tuberculosis specific metabolite. In this paper, it is assumed that the selected probe is specific to niacin and that exhaled breath does not contain any interfering species. To address this problem, a fluorimeter is developed with a cheap and cooled CCD (? 2k$) as a sensor, to easily determine the suitable "fluorescent zone". In comparing aqueous solutions with and without niacin, 250 pM of niacin have been detected. With a commercial fluorimeter (Fluorolog from Horiba), only 200 nM of niacin are detected. The present detection remains 10 times above the estimated targeted value for a tuberculosis test. The excitation source is a LED, which typically emits 20 °W at 265 nm through an optical fiber. The emission signal is detected around 545 nm. A typical light exposure lasts 700 seconds. Analysis of biomarkers with a liquid fluorimeter is generic and promising as health diagnosis.

  9. Non-Fermi-liquid behavior in the fluctuating gap model: From the pole to a zero of the Green's function

    SciTech Connect

    Kuchinskii, E. Z.; Sadovskii, M. V.

    2006-09-15

    We analyze the non-Fermi-liquid (NFL) behavior of the fluctuating gap model (FGM) of pseudogap behavior in both one and two dimensions. A detailed discussion of quasiparticle renormalization (Z-factor) is given, demonstrating a kind of marginal Fermi-liquid or Luttinger-liquid behavior and topological stability of the bare Fermi surface (the Luttinger theorem). In the two-dimensional case, we discuss the effective picture of the Fermi surface destruction both in the hot spot model of dielectric (AFM, CDW) pseudogap fluctuations and for the qualitatively different case of superconducting d-wave fluctuations, reflecting the NFL spectral density behavior and similar to that observed in ARPES experiments on copper oxides.

  10. Bose-Fermi Pairs in a Mixture and the Luttinger Theorem within a Nozieres-Schmitt-Rink like Approach

    E-print Network

    T. Sogo; P. Schuck; M. Urban

    2013-07-03

    Bose-Fermion pair correlations in a mixture are considered at zero temperature in the T-matrix approximation. Special attention is paid to the Luttinger theorem. In a strict RPA variant of the Nozieres-Schmitt-Rink approach, it is shown that this theorem is respected also in the homogeneous infinite matter case. We calculate the corresponding occupation numbers of fermions and bosons and the condensate depletion. We also show that in the limit of very small boson density, our results are in good agreement with the results found in the literature for the Fermi polaron in strongly imbalanced Fermi-Fermi mixtures.

  11. The Kohn-Luttinger mechanism and phase diagram of the superconducting state in the Shubin-Vonsovsky model

    SciTech Connect

    Kagan, M. Yu.; Val'kov, V. V.; Mitskan, V. A.; Korovuskin, M. M.

    2013-10-15

    Using the Shubin-Vonsovsky model in the weak-coupling regime W > U > V (W is the bandwidth, U is the Hubbard onsite repulsion, and V is the Coulomb interaction at neighboring sites) based on the Kohn-Luttinger mechanism, we determined the regions of the existence of the superconducting phases with the d{sub xy}, p, s, and d{sub x{sup 2}-y{sup 2}} symmetry types of the order parameter. It is shown that the effective interaction in the Cooper channel considerably depends not only on single-site but also on intersite Coulomb correlations. This is demonstrated by the example of the qualitative change and complication of the phase diagram of the superconducting state. The superconducting (SC) phase induction mechanism is determined taking into account polarization contributions in the second-order perturbation theory in the Coulomb interaction. The results obtained for the angular dependence of the superconducting gap in different channels are compared with angule-resolved photoemission spectroscopy (ARPES) results. The influence of long-range hops in the phase diagram and critical superconducting transition temperature in different channels is analyzed. The conditions for the appearance of the Kohn-Luttinger superconductivity with the d{sub x{sup 2}-y{sup 2}} symmetry and high critical temperatures T{sub c} {approx} 100 K near the half-filling are determined.

  12. Excited-State Tautomerization of 7-Azaindole in Nonpolar Solution: A Theoretical Study Based on Liquid-Phase Potential Surfaces of Mean Force.

    PubMed

    Fang, Hua; Kim, Yongho

    2013-08-13

    Excited state tautomerization of a 7-azaindole (7AI) complex with one methanol molecule in heptane was studied using variational transition state theory including multidimensional tunneling (VTST/MT) with the dielectric continuum model for the solvent effect. Electronic structures and energies for reactants and transition state (TS) in solution were computed at the complete active space self-consistent field (CASSCF) level with second-order multireference perturbation theory (MRPT2) to take into consideration of dynamic electron correlation. The polarizable continuum model using the integral equation formalism (IEFPCM) and the SMD model were used for the excited-state solvent effect. Excited-state surfaces of potential of the mean force in solution were generated for the first time at the MRPT2//SMD/CASSCF(10,9)/6-31G(d,p) level. The position of TS on the reaction coordinate substantially depended on the dynamic electron correlation. The two protons in the excited-state tautomerization were transferred in a concerted but asynchronous process. Calculated HH/DD kinetic isotope effect (KIE) and the ratio of Arrhenius pre-exponential factors, A(HH)/A(DD), agreed very well with the corresponding experimental values. The shape of the adiabatic energy surfaces in the excited-state strongly depended on the position of isotopes due to the asynchronicity of the reaction path, and the tunneling effect was essential for reproducing experimental KIEs. The pyrrolic proton moved a twice longer distance by tunneling than the hydroxyl proton in the most probable tunneling path at 292 K. This study strongly suggests that the mechanism of the excited-state double proton transfer in heptane is triggered by proton transfer from the pyrrolic nitrogen of 7AI to alcohol (protolytic pathway), rather than by proton transfer from alcohol to the pyridine nitrogen of 7AI (solvolytic pathway). PMID:26584111

  13. Intermittent Magnetic Field Excitation by a Turbulent Flow of Liquid Sodium M. D. Nornberg, E. J. Spence, R. D. Kendrick, C. M. Jacobson, and C. B. Forest*

    E-print Network

    Wisconsin at Madison, University of

    such as the Earth, the Sun, and the Galaxy self-generate magnetic fields. These onset conditions are now being with predictions from the kinematic theory. Fluids and plasmas such as the Earth's liquid core, the solar prompted the creation of several experi- ments to investigate the dynamo onset conditions in simply

  14. Ambiguity in renormalization of the conductance of an X-junction between quantum wires with a Luttinger-type interaction

    NASA Astrophysics Data System (ADS)

    Aristov, D. N.; Niyazov, R. A.

    2015-10-01

    We study the conductance renormalization for the four-lead junction of semi-infinite wires in the scattering state formalism. We use the model of spinless fermions with a short-range Luttinger-type interaction and find the renormalization group (RG) equations for the conductances of the system in the first order of the fermionic interaction. In contrast to the well-known cases of two-lead and three-lead junctions, the four-lead case does not admit a formulation of the RG equations solely in terms of conductances. The arising ambiguity with arbitrariness in the choice of the sign of S-matrix elements related to identical conductance matrices might be connected with a symmetry of the particle-hole type in the Hamiltonian. We show that there are two distinct RG flows from any initial point in the space of conductances. The discovered ambiguity does not affect the scaling exponents at the fixed points.

  15. PREFACE: Functionalized Liquid Liquid Interfaces

    NASA Astrophysics Data System (ADS)

    Girault, Hubert; Kornyshev, Alexei A.; Monroe, Charles W.; Urbakh, Michael

    2007-09-01

    Most natural processes take place at interfaces. For this reason, surface science has been a focal point of modern research. At solid-liquid interfaces one can induce various species to adsorb or react, and thus may study interactions between the substrate and adsorbates, kinetic processes, optical properties, etc. Liquid-liquid interfaces, formed by immiscible liquids such as water and oil, have a number of distinctive features. Both sides of the interface are amenable to detailed physical and chemical analysis. By chemical or electrochemical means, metal or semiconductor nanoparticles can be formed or localised at the interface. Surfactants can be used to tailor surface properties, and also to place organic molecular or supermolecular constructions at the boundary between the liquids. Electric fields can be used to drive ions from one fluid to another, or even change the shape of the interface itself. In many cases, both liquids are optically transparent, making functionalized liquid-liquid interfaces promising for various optical applications based on the transmission or reflection of light. An advantage common to most of these systems is self-assembly; because a liquid-liquid interface is not mechanically constrained like a solid-liquid interface, it can easily access its most stable state, even after it has been driven far from equilibrium. This special issue focuses on four modes of liquid-liquid interfacial functionalization: the controlled adsorption of molecules or nanoparticles, the formation of adlayers or films, electrowetting, and ion transfer or interface-localized reactions. Interfacial adsorption can be driven electrically, chemically, or mechanically. The liquid-liquid interface can be used to study how anisotropic particles orient at a surface under the influence of a field, how surfactants interact with other adsorbates, and how nanoparticles aggregate; the transparency of the interface also makes the chirality of organic adsorbates amenable to optical study. Film formation goes a step beyond adsorption; some surfactants form monolayers or multilayers at the interface. A polymer microfilm or a polymer-particle matrix can be synthesized at the liquid-liquid boundary. Such films exhibit unique adsorption and ion-intercalation properties of their own. Electrowetting refers broadly to the phenomenon in which an applied voltage modulates the shape of a liquid-liquid interface, essentially by altering the surface tension. Electric fields can be used to induce droplets on solid substrates to change shape, or to affect the structure of liquid-liquid emulsions. Various chemical reactions can be performed at the liquid-liquid boundary. Liquid-liquid microelectrodes allow detailed study of ion-transfer kinetics at the interface. Photochemical processes can also be used to control the conformations of molecules adsorbed at the interface. But how much precise control do we actually have on the state of the interfacial region? Several contributions to this issue address a system which has been studied for decades in electrochemistry, but remains essentially unfamilar to physicists. This is the interface between two immiscible electrolytic solutions (ITIES), a progressing interdisciplinary field in which condensed-matter physics and physical chemistry meet molecular electrochemistry. Why is it so exciting? The reason is simple. The ITIES is chargeable: when positioned between two electrodes it can be polarized, and back- to-back electrical double layers form on both sides of the liquid-liquid interface. Importantly, the term immiscible refers not only to oil and water but also to the electrolytes. Inorganic electrolytes, such as alkali halides, tend to stay in water, whereas organic electrolytes, such as tetrabutylammonium tetraphenylborate, stay in oil. This behaviour arises because energies of the order of 0.2-0.3 eV are needed to drive ions across the interface. As long as these free energies of transfer are not exceeded by the external potential bias, the ITIES works as an 'electrode'; there is no traffic of ions

  16. Magnetostrictive resonance excitation

    DOEpatents

    Schwarz, Ricardo B. (Los Alamos, NM); Kuokkala, Veli-Tapani (Tampere, FI)

    1992-01-01

    The resonance frequency spectrum of a magnetostrictive sample is remotely determined by exciting the magnetostrictive property with an oscillating magnetic field. The permeability of a magnetostrictive material and concomitant coupling with a detection coil varies with the strain in the material whereby resonance responses of the sample can be readily detected. A suitable sample may be a magnetostrictive material or some other material having at least one side coated with a magnetostrictive material. When the sample is a suitable shape, i.e., a cube, rectangular parallelepiped, solid sphere or spherical shell, the elastic moduli or the material can be analytically determined from the measured resonance frequency spectrum. No mechanical transducers are required and the sample excitation is obtained without contact with the sample, leading to highly reproducible results and a measurement capability over a wide temperature range, e.g. from liquid nitrogen temperature to the Curie temperature of the magnetostrictive material.

  17. Excited Insects

    E-print Network

    Hacker, Randi

    2011-04-06

    but not killing them doesn't actually count as true celebration. Now, China. There's a country that knows how to make a bug feel good. Bugs have their very own holiday in the Chinese calendar. It's called the Feast of the Excited Insects and it falls on March 5th...

  18. Excited Delirium

    PubMed Central

    Takeuchi, Asia; Ahern, Terence L.; Henderson, Sean O.

    2011-01-01

    Excited (or agitated) delirium is characterized by agitation, aggression, acute distress and sudden death, often in the pre-hospital care setting. It is typically associated with the use of drugs that alter dopamine processing, hyperthermia, and, most notably, sometimes with death of the affected person in the custody of law enforcement. Subjects typically die from cardiopulmonary arrest, although the cause is debated. Unfortunately an adequate treatment plan has yet to be established, in part due to the fact that most patients die before hospital arrival. While there is still much to be discovered about the pathophysiology and treatment, it is hoped that this extensive review will provide both police and medical personnel with the information necessary to recognize and respond appropriately to excited delirium. PMID:21691475

  19. Excited baryons

    SciTech Connect

    Mukhopadhyay, N.C.

    1986-01-01

    The status of the theory of the low-energy approach to hadron structure is reviewed briefly by surveying a few relevant models. A few examples of tests needed to sort out the predictions of different models pertaining to the quark-gluon structure of hadrons are discussed, and given the resulting physics objectives, a few experimental options for excited baryon research at CFBAF are suggested. (LEW)

  20. Determination of high-molecular weight polycyclic aromatic hydrocarbons in high performance liquid chromatography fractions of coal tar standard reference material 1597a via solid-phase nanoextraction and laser-excited time-resolved Shpol'skii spectroscopy.

    PubMed

    Wilson, Walter B; Alfarhani, Bassam; Moore, Anthony F T; Bisson, Cristina; Wise, Stephen A; Campiglia, Andres D

    2016-02-01

    This article presents an alternative approach for the analysis of high molecular weight - polycyclic aromatic hydrocarbons (HMW-PAHs) with molecular mass 302Da in complex environmental samples. This is not a trivial task due to the large number of molecular mass 302Da isomers with very similar chromatographic elution times and similar, possibly even virtually identical, mass fragmentation patterns. The method presented here is based on 4.2K laser-excited time-resolved Shpol'skii spectroscopy, a high resolution spectroscopic technique with the appropriate selectivity for the unambiguous determination of PAHs with the same molecular mass. The potential of this approach is demonstrated here with the analysis of a coal tar standard reference material (SRM) 1597a. Liquid chromatography fractions were submitted to the spectroscopic analysis of five targeted isomers, namely dibenzo[a,l]pyrene, dibenzo[a,e]pyrene, dibenzo[a,i]pyrene, naphtho[2,3-a]pyrene and dibenzo[a,h]pyrene. Prior to analyte determination, the liquid chromatographic fractions were pre-concentrated with gold nanoparticles. Complete analysis was possible with microliters of chromatographic fractions and organic solvents. The limits of detection varied from 0.05 (dibenzo[a,l]pyrene) to 0.24µgL(-1) (dibenzo[a,e]pyrene). The excellent analytical figures of merit associated to its non-destructive nature, which provides ample opportunity for further analysis with other instrumental methods, makes this approach an attractive alternative for the determination of PAH isomers in complex environmental samples. PMID:26653471

  1. Particle Beam Excitation Electron Beam Excitation

    E-print Network

    Schroder, Dieter K.

    Particle Beam Excitation Electron Beam Excitation Scanning Electron Microscopy (SEM) Electron Microprobe Microanalysis (EMP) Transmission Electron Microscopy (TEM) Scanning Auger Microscopy (SAM Backscattering Spectrometry (RBS) X-ray Excitation X-ray Fluorescence (XRF) X-ray Photoelectron Spectroscopy (XPS

  2. Rashba coupling and magnetic order in correlated helical liquids

    NASA Astrophysics Data System (ADS)

    Hohenadler, Martin; Assaad, Fakher F.

    2014-12-01

    We study strongly correlated helical liquids with and without Rashba coupling using quantum Monte Carlo simulations of the Kane-Mele model with a Hubbard interaction at the edge. Independent of the Rashba coupling, we find that interactions enhance spin correlations and suppress the spectral weight at the Fermi level. For sufficiently strong interactions, a gap can be observed in the single-particle spectral function. However, based on a finite-size scaling analysis and theoretical arguments, we argue that this gap is closed by order parameter fluctuations in the Luttinger liquid phase even at zero temperature, and filled in by thermally induced kinks in the order parameter in the Mott phase at finite temperatures. While the bosonization suggests an umklapp-driven Mott transition only in the presence of Rashba coupling and hence a significant impact of the latter, our numerical results are almost unaffected by Rashba coupling even at low temperatures.

  3. Universal nature of collective plasmonic excitations in finite 1-D carbon-based nanostructures

    E-print Network

    Polizzi, Eric

    2015-01-01

    Tomonaga-Luttinger (T-L) theory predicts collective plasmon resonances in 1-D nanostructure conductors of finite length, that vary roughly in inverse proportion to the length of the structure. Yet, such resonances have not been clearly identified in experiments so far. Here we provide evidence of the T-L plasmon resonances using first-principle computational real-time spectroscopy studies of representative finite 1-D carbon-based nanostructures ranging from atom and benzene-like chain structures to short carbon nanotubes. Our all-electron Time-Dependent Density-Functional Theory (TDDFT) real-time simulation framework is capable to accurately capture the relevant nanoscopic effects including correct frequencies for known optical transitions, and various collective plasmon excitations. The presence of 1-D T-L plasmons is universally predicted by the various numerical experiments, which also demonstrate a phenomenon of resonance splitting. Extending these simulations to longer structures will allow the accurate ...

  4. Caged spin-orbit excited I*,,2 P1/2... I*,,2

    E-print Network

    Apkarian, V. Ara

    Caged spin-orbit excited I*,,2 P1/2... I*,,2 P1/2... atom pairs in liquids and in cryogenic 1997 Two-photon excitation of I2 in room temperature liquid solutions and in cryogenic rare gas.8 s, in Ar, Kr, and Xe. In room temperature liquids, emission from both geminate and nongeminate pairs

  5. Liquid White Enamel.

    ERIC Educational Resources Information Center

    Widmar, Marge

    1985-01-01

    A secondary teacher describes how she has her students use liquid white enamel. With the enameling process, students can create lasting, exciting artwork. They can exercise an understanding of design and color while learning the value of careful, sustained craft skills. (RM)

  6. Strongly Coupled Plasma Liquids

    E-print Network

    Z. Donko; P. Hartmann; G. J. Kalman

    2007-10-27

    This paper intends to review some of the prominent properties of strongly coupled classical plasmas having in mind the possible link with the quark-gluon plasma created in heavy-ion collisions. Thermodynamic and transport properties of classical liquid-state one-component plasmas are described and features of collective excitations are presented.

  7. Fermi Surface Evolution and Luttinger Theorem in NaxCoO2: A Systematic Photoemission Study

    SciTech Connect

    Yang, H. B.; Pan, Z. H.; Sekharan, A. K. P.; Sato, T.; Souma, S.; Takahashi, T.; Jin, Rongying; Sales, Brian C; Mandrus, David; Fedorov, A. V.; Wang, Z.; Ding, H.

    2005-01-01

    We report a systematic angle-resolved photoemission study on Na{sub x}CoO{sub 2} for a wide range of Na concentrations (0.3 {le} x {le} 0.72). In all the metallic samples at different x, we observed (i) only a single holelike Fermi surface centered around {Gamma} and (ii) its area changes with x according to the Luttinger theorem. We also observed a surface state that exhibits a larger Fermi surface area. The e{prime}{sub g} band and the associated small Fermi surface pockets near the K points predicted by band calculations are found to sink below the Fermi energy in a manner almost independent of the doping and temperature.

  8. Detecting crystal symmetry fractionalization from the ground state: Application to Z[subscript 2] spin liquids on the kagome lattice

    E-print Network

    Qi, Yang

    In quantum spin liquid states, the fractionalized spinon excitations can carry fractional crystal symmetry quantum numbers, and this symmetry fractionalization distinguishes different symmetry-enriched spin liquid states ...

  9. Regular and singular Fermi liquid in triple quantum dots: Coherent transport studies

    NASA Astrophysics Data System (ADS)

    Tooski, S. B.; Ramšak, A.; Bu?ka, B. R.

    2016-01-01

    A system of three coupled quantum dots in a triangular geometry (TQD) with electron-electron interaction and symmetrically coupled to two leads is analyzed with respect to the electron transport by means of the numerical renormalization group. Varying gate potentials this system exhibits extremely rich range of regimes with different many-electron states with various local spin orderings. It is demonstrated how the Luttinger phase changes in a controlled manner which then via the Friedel sum rule formula exactly reproduces the conductance through the TQD system. The analysis of the uncoupled TQD molecule from the leads gives a reliable qualitative understanding of various relevant regimes and an insight into the phase diagram with the regular Fermi liquid and singular-Fermi liquid phases.

  10. Anomalous chiral Luttinger liquid behavior of diluted fractionally charged quasiparticles Y. C. Chung, M. Heiblum, Y. Oreg, V. Umansky, and D. Mahalu

    E-print Network

    Heiblum, Mordehai "Moty"

    -temperatures backscattering events were found to be strongly correlated, producing a highly nonlinear current of Condensed Matter Physics, Weizmann Institute of Science, Rehovot 76100, Israel Received 1 April 2003. This is the well-known fractional quantum Hall effect FQHE .2 The current, carried by the quasiparticles, flows

  11. Non-Fermi-liquid and topological states with strong spin-orbit coupling.

    PubMed

    Moon, Eun-Gook; Xu, Cenke; Kim, Yong Baek; Balents, Leon

    2013-11-15

    We argue that a class of strongly spin-orbit-coupled materials, including some pyrochlore iridates and the inverted band gap semiconductor HgTe, may be described by a minimal model consisting of the Luttinger Hamiltonian supplemented by Coulomb interactions, a problem studied by Abrikosov and collaborators. It contains twofold degenerate conduction and valence bands touching quadratically at the zone center. Using modern renormalization group methods, we update and extend Abrikosov's classic work and show that interactions induce a quantum critical non-Fermi-liquid phase, stable provided time-reversal and cubic symmetries are maintained. We determine the universal power-law exponents describing various observables in this Luttinger-Abrikosov-Beneslavskii state, which include conductivity, specific heat, nonlinear susceptibility, and the magnetic Gruneisen number. Furthermore, we determine the phase diagram in the presence of cubic and/or time-reversal symmetry breaking perturbations, which includes a topological insulator and Weyl semimetal phases. Many of these phases possess an extraordinarily large anomalous Hall effect, with the Hall conductivity scaling sublinearly with magnetization ?(xy)?M0.51. PMID:24289698

  12. Acoustically excited heated jets. 1: Internal excitation

    NASA Technical Reports Server (NTRS)

    Lepicovsky, J.; Ahuja, K. K.; Brown, W. H.; Salikuddin, M.; Morris, P. J.

    1988-01-01

    The effects of relatively strong upstream acoustic excitation on the mixing of heated jets with the surrounding air are investigated. To determine the extent of the available information on experiments and theories dealing with acoustically excited heated jets, an extensive literature survey was carried out. The experimental program consisted of flow visualization and flowfield velocity and temperature measurements for a broad range of jet operating and flow excitation conditions. A 50.8-mm-diam nozzle was used for this purpose. Parallel to the experimental study, an existing theoretical model of excited jets was refined to include the region downstream of the jet potential core. Excellent agreement was found between theory and experiment in moderately heated jets. However, the theory has not yet been confirmed for highly heated jets. It was found that the sensitivity of heated jets to upstream acoustic excitation varies strongly with the jet operating conditions and that the threshold excitation level increases with increasing jet temperature. Furthermore, the preferential Strouhal number is found not to change significantly with a change of the jet operating conditions. Finally, the effects of the nozzle exit boundary layer thickness appear to be similar for both heated and unheated jets at low Mach numbers.

  13. Non-existence of the Luttinger-Ward functional and misleading convergence of skeleton diagrammatic series for Hubbard-like models

    E-print Network

    Evgeny Kozik; Michel Ferrero; Antoine Georges

    2015-04-17

    The Luttinger-Ward functional $\\Phi[\\mathbf{G}]$, which expresses the thermodynamic grand potential in terms of the interacting single-particle Green's function $\\mathbf{G}$, is found to be ill-defined for fermionic models with the Hubbard on-site interaction. In particular, we show that the self-energy $\\mathbf{\\Sigma}[\\mathbf{G}] \\propto \\delta\\Phi[\\mathbf{G}]/\\delta \\mathbf{G}$ is not a single-valued functional of $\\mathbf{G}$: in addition to the physical solution for $\\mathbf{\\Sigma}[\\mathbf{G}]$, there exists at least one qualitatively distinct unphysical branch. This result is demonstrated for several models: the Hubbard atom, the Anderson impurity model, and the full two-dimensional Hubbard model. Despite this pathology, the skeleton Feynman diagrammatic series for $\\mathbf{\\Sigma}$ in terms of $\\mathbf{G}$ is found to converge at least for moderately low temperatures. However, at strong interactions, its convergence is to the unphysical branch. This reveals a new scenario of breaking down of diagrammatic expansions. In contrast, the bare series in terms of the non-interacting Green's function $\\mathbf{G}_0$ converges to the correct physical branch of $\\mathbf{\\Sigma}$ in all cases currently accessible by diagrammatic Monte Carlo. Besides their conceptual importance, these observations have important implications for techniques based on the explicit summation of diagrammatic series.

  14. Discrete approach to incoherent excitations in conductors

    E-print Network

    P. Zupanovic; A. Bjelis; Z. Agic

    2002-06-14

    Keeping the discretness of the reciprocal space we calculate the spectrum of incoherent electron-hole excitations in the conducting Fermi liquids. The metod is illustrated on the well-known jellium model within the random phase approximation. It also leads to the formulation os a sum rule from which we get the details os dispersion curve for the collective plasmon mode. The notion of time averaging in the discrete approach is briefly recalled.

  15. Non-Fermi Liquid Photoemission Line Shapes in Quasi-One-Dimensional Mo Bronzes

    NASA Astrophysics Data System (ADS)

    Gweon, Gey-Hong

    2001-03-01

    Quasi-one-dimensional (quasi-1d) ``K blue bronze'' K_0.3MoO3 and ``Li purple bronze'' Li_0.9Mo_6O_17 both show non-Fermi liquid angle resolved photoemission (ARPES) line shapes in their metallic phases [1,2]. The former has a charge density wave (CDW) transition at T_CDW=180 K, and the latter a transition of an unknown origin at T_X=24 K without any electronic gap opening across T_X. We show that the non-CDW Li purple bronze is so far a unique example where normal state ARPES line shapes can be meaningfully and favorably compared with a purely Luttinger liquid line shape. We show that the PES line shapes for the K blue bronze are not easily understood within a fluctuation-induced CDW pseudo-gap model, implying the need to include electron correlations. Detailed T-dependent ARPES data show little peak movement but only an intensity redistribution across T_CDW, reminiscent of recent quasi-1d theory for dimensional cross-over in a superconducting transition [3]. While neither material is fully described by present line shape theories, we argue that the Li purple and the K blue bronzes can be characterized, respectively, as Tomonaga-Luttinger and Luther-Emery liquids, the latter consistent with an early suggestion of Voit [4]. [1] G.-H. Gweon et al, J. Phys.-Condens. Matter 8, 9923 (1996). [2] J.D. Denlinger et al, Phys. Rev. Lett. 82, 2540 (1999); G.-H. Gweon et al, Phys. Rev. Lett. 85, 3985 (2000). [3] E.W. Carlson et al, Phys. Rev. B 62, 3422 (2000). [4] J. Voit, J. Phys.-Condens. Matter 5, 8305 (1993).

  16. BROADBAND EXCITATION IN NUCLEAR MAGNETIC RESONANCE

    SciTech Connect

    Tycko, R.

    1984-10-01

    Theoretical methods for designing sequences of radio frequency (rf) radiation pulses for broadband excitation of spin systems in nuclear magnetic resonance (NMR) are described. The sequences excite spins uniformly over large ranges of resonant frequencies arising from static magnetic field inhomogeneity, chemical shift differences, or spin couplings, or over large ranges of rf field amplitudes. Specific sequences for creating a population inversion or transverse magnetization are derived and demonstrated experimentally in liquid and solid state NMR. One approach to broadband excitation is based on principles of coherent averaging theory. A general formalism for deriving pulse sequences is given, along with computational methods for specific cases. This approach leads to sequences that produce strictly constant transformations of a spin system. The importance of this feature in NMR applications is discussed. A second approach to broadband excitation makes use of iterative schemes, i.e. sets of operations that are applied repetitively to a given initial pulse sequences, generating a series of increasingly complex sequences with increasingly desirable properties. A general mathematical framework for analyzing iterative schemes is developed. An iterative scheme is treated as a function that acts on a space of operators corresponding to the transformations produced by all possible pulse sequences. The fixed points of the function and the stability of the fixed points are shown to determine the essential behavior of the scheme. Iterative schemes for broadband population inversion are treated in detail. Algebraic and numerical methods for performing the mathematical analysis are presented. Two additional topics are treated. The first is the construction of sequences for uniform excitation of double-quantum coherence and for uniform polarization transfer over a range of spin couplings. Double-quantum excitation sequences are demonstrated in a liquid crystal system. The second additional topic is the construction of iterative schemes for narrowband population inversion. The use of sequences that invert spin populations only over a narrow range of rf field amplitudes to spatially localize NMR signals in an rf field gradient is discussed.

  17. 8. POWERHOUSE INTERIOR SHOWING EXCITER No. 1 IN FOREGROUND, EXCITER ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    8. POWERHOUSE INTERIOR SHOWING EXCITER No. 1 IN FOREGROUND, EXCITER No. 2., AND GENERATOR UNITS BEHIND EXCITER No. 2 IN BACKGROUND. EXCITER No. 1 GENERATOR HAS A COVER OVER TOP HALF OF COMMUTATOR ELEMENT. VIEW TO NORTHWEST. - Rush Creek Hydroelectric System, Powerhouse Exciters, Rush Creek, June Lake, Mono County, CA

  18. The Prediction of a Gapless Topological "Haldane Liquid" Phase in a One-Dimensional Cold Polar Molecular Lattice

    E-print Network

    J. P. Kestner; Bin Wang; Jay D. Sau; S. Das Sarma

    2011-04-28

    We show that ultracold two-component fermionic dipolar gases in an optical lattice with strong two-body on-site loss can be used to realize a tunable effective spin-one model. Fermion number conservation provides an unusual constraint that $\\sum_i (S^z_i)^2$ is conserved, leading to a novel topological liquid phase in one dimension which can be thought of as the gapless analog of the Haldane gapped phase of a spin-one Heisenberg chain. The properties of this phase are calculated numerically via the infinite time-evolving block decimation method and analytically via a mapping to a one-mode Luttinger liquid with hidden spin information.

  19. The `strange metal' is a projected Fermi liquid with edge singularities

    E-print Network

    Loss, Daniel

    ARTICLES The `strange metal' is a projected Fermi liquid with edge singularities P. W. ANDERSON in the X-ray spectra of metals, we find a Fermi-liquid-like excitation spectrum, but the excitations is `strange metal'1 ; another is `marginal Fermi liquid'2 . The defining characteristic

  20. Collective excitations on a surface of topological insulator

    PubMed Central

    2012-01-01

    We study collective excitations in a helical electron liquid on a surface of three-dimensional topological insulator. Electron in helical liquid obeys Dirac-like equation for massless particles and direction of its spin is strictly determined by its momentum. Due to this spin-momentum locking, collective excitations in the system manifest themselves as coupled charge- and spin-density waves. We develop quantum field-theoretical description of spin-plasmons in helical liquid and study their properties and internal structure. Value of spin polarization arising in the system with excited spin-plasmons is calculated. We also consider the scattering of spin-plasmons on magnetic and nonmagnetic impurities and external potentials, and show that the scattering occurs mainly into two side lobes. Analogies with Dirac electron gas in graphene are discussed. PACS: 73.20.Mf; 73.22.Lp; 75.25.Dk. PMID:22376744

  1. Collective excitations in solids

    SciTech Connect

    Di Bartolo, B.

    1983-01-01

    This book is based on the NATO Advanced Study Institute on ''Collective Excitations in Solids'' held in Italy in 1981. The objective of the Institute was to formulate a unified and coherent treatment of various collective excitation processes by drawing on the current advances in various branches of the physics of the solid state. Topics include the quantum mechanical description of solids; an introduction to collective excitations in solids; quasi-particles and excitons (models of structure and correlation); coherent wavepackets of phonons; an introduction to exciton physics; excitons in semiconductors; excitons in insulators; inelastic scattering of fast particles by plasmons; from magnons to solitons; quasiparticles in magnetic metals; polaritons; polarons; surface collective excitations; collective excitations in concentrated Mn/sup 2 +/ systems (spectral properties); optical dynamics in concentrated Mn/sup 2 +/ systems; spectroscopy of stoichiometric laser materials (excitons or incoherent transfers.); exciton-hole droplets in semiconductors; excitons and plasmons (collective excitations in semiconductors); picosecond exciton phenomena in chlorophyll complexes; and present trends in collective excitations in solids.

  2. Excitability dependent pattern formation

    NASA Astrophysics Data System (ADS)

    Prabhakara, Kaumudi; Gholami, Azam; Bodenschatz, Eberhard

    2014-03-01

    On starvation, the amoebae Dictyostelium discoideum emit the chemo-attractant cyclic adenosine monophosphate (cAMP) at specific frequencies. The neighboring amoebae sense cAMP through membrane receptors and produce their own cAMP. Soon the cells synchronize and move via chemotaxis along the gradient of cAMP. The response of the amoebae to the emission of cAMP is seen as spiral waves or target patterns under a dark field microscope. The causal reasons for the selection of one or the other patterns are still unclear. Here we present a possible explanation based on excitability. The excitability of the amoebae depends on the starvation time because the gene expression changes with starvation. Cells starved for longer times are more excitable. In this work, we mix cells of different excitabilities to study the dependence of the emergent patterns on the excitability. Preliminary results show a transition from spirals to target patterns for specific excitabilities. A phase map of the patterns for different combinations of excitability and number densities is obtained. We compare our findings with numerical simulations of existing theoretical models.

  3. Medium-frequency impulsive-thrust-excited slosh waves during propellant reorientation with a geyser

    NASA Technical Reports Server (NTRS)

    Hung, R. J.; Shyu, K. L.; Lee, C. C.

    1992-01-01

    Slosh wave excitation induced by a resettling flowfield activated by 1.0-Hz impulsive thrust during the course of liquid reorientation with the initiation of geyser for liquid-fill levels of 30, 50, 65, 70, and 80 percent has been studied. Characteristics of slosh waves of various frequencies excited by the resettling flowfield are discussed. Slosh wave excitations shift the fluid mass distribution in the container which imposes time-dependent variations in spacecraft moment of inertia. This information is important for spacecraft control during the course of liquid reorientation.

  4. Excitation Methods for Bridge Structures

    SciTech Connect

    Farrar, C.R.; Duffy, T.A.; Cornwell, P.J.; Doebling, S.W.

    1999-02-08

    This paper summarizes the various methods that have been used to excited bridge structures during dynamic testing. The excitation methods fall into the general categories of ambient excitation methods and measured-input excitation methods. During ambient excitation the input to the bridge is not directly measured. In contrast, as the category label implies, measured-input excitations are usually applied at a single location where the force input to the structure can be monitored. Issues associated with using these various types of measurements are discussed along with a general description of the various excitation methods.

  5. Excitations Propagating Along Surfaces

    E-print Network

    A. V. Stoyanovsky

    2006-05-22

    A number of equations is deduced which describe propagation of excitations along $n$-dimensional surfaces in $R^N$. Usual excitations in wave theory propagate along 1-dimensional trajectories. The role of the medium of propagation of excitations considered in this paper is played by the infinite dimensional space of $(n-1)$-dimensional surfaces in $R^N$. The role of rays is played by $n$-dimensional solution surfaces of the variational problem. Such a generalization of wave theory can be useful in quantum field theory. Among these equations are the generalized Hamilton--Jacobi equation (known in particular cases in the literature), generalized canonical Hamilton equations, and generalized Schrodinger equation. Besides that, a theory of integration of the generalized Hamilton--Jacobi equation is developed.

  6. Photothermal excitation setup for a modified commercial atomic force microscope.

    PubMed

    Adam, Holger; Rode, Sebastian; Schreiber, Martin; Kobayashi, Kei; Yamada, Hirofumi; Kühnle, Angelika

    2014-02-01

    High-resolution imaging in liquids using frequency modulation atomic force microscopy is known to suffer from additional peaks in the resonance spectrum that are unrelated to the cantilever resonance. These unwanted peaks are caused by acoustic modes of the liquid and the setup arising from the indirect oscillation excitation by a piezoelectric transducer. Photothermal excitation has been identified as a suitable method for exciting the cantilever in a direct manner. Here, we present a simple design for implementing photothermal excitation in a modified Multimode scan head from Bruker. Our approach is based on adding a few components only to keep the modifications as simple as possible and to maintain the low noise level of the original setup with a typical deflection noise density of about 15 fm/?[Hz] measured in aqueous solution. The success of the modification is illustrated by a comparison of the resonance spectra obtained with piezoelectric and photothermal excitation. The performance of the systems is demonstrated by presenting high-resolution images on bare calcite in liquid as well as organic adsorbates (Alizarin Red S) on calcite with simultaneous atomic resolution of the underlying calcite substrate. PMID:24593367

  7. Photothermal excitation setup for a modified commercial atomic force microscope

    SciTech Connect

    Adam, Holger; Rode, Sebastian; Schreiber, Martin; Kühnle, Angelika; Kobayashi, Kei; Yamada, Hirofumi

    2014-02-15

    High-resolution imaging in liquids using frequency modulation atomic force microscopy is known to suffer from additional peaks in the resonance spectrum that are unrelated to the cantilever resonance. These unwanted peaks are caused by acoustic modes of the liquid and the setup arising from the indirect oscillation excitation by a piezoelectric transducer. Photothermal excitation has been identified as a suitable method for exciting the cantilever in a direct manner. Here, we present a simple design for implementing photothermal excitation in a modified Multimode scan head from Bruker. Our approach is based on adding a few components only to keep the modifications as simple as possible and to maintain the low noise level of the original setup with a typical deflection noise density of about 15 fm/?(Hz) measured in aqueous solution. The success of the modification is illustrated by a comparison of the resonance spectra obtained with piezoelectric and photothermal excitation. The performance of the systems is demonstrated by presenting high-resolution images on bare calcite in liquid as well as organic adsorbates (Alizarin Red S) on calcite with simultaneous atomic resolution of the underlying calcite substrate.

  8. Angle resolved photoemission study of Fermi surfaces and single-particle excitations of quasi-low dimensional materials

    NASA Astrophysics Data System (ADS)

    Gweon, Gey-Hong

    Using angle resolved photoemission spectroscopy (ARPES) as the main experimental tool and the single particle Green's function as the main theoretical tool, materials of various degrees of low dimensionality and different ground states are studied. The underlying theme of this thesis is that of one dimensional physics, which includes charge density waves (CDW's) and the Luttinger liquid (LL). The LL is the prime example of a lattice non-Fermi liquid (non-FL) and CDW fluctuations also give non-FL behaviors. Non-FL physics is an emerging paradigm of condensed matter physics. It is thought by some researchers that one dimensional LL behavior is a key element in solving the high temperature superconductivity problem. TiTe2 is a quasi-2 dimensional (quasi-2D) Fermi liquid (FL) material very well suited for ARPES lineshape studies. I report ARPES spectra at 300 K which show an unusual behavior of a peak moving through the Fermi energy (EF). I also report a good fit of the ARPES spectra at 25 K obtained by using a causal Green's function proposed by K. Matho. SmTe3 is a quasi-2D CDW material. The near EF ARPES spectra and intensity map reveal rich details of an anisotropic gap and imperfectly nested Fermi surface (FS) for a high temperature CDW. A simple model of imperfect nesting can be constructed from these data and predicts a CDW wavevector in very good agreement with the value known from electron diffraction. NaMo6O17 and KMo 6O17 are also quasi-2D CDW materials. The "hidden nesting" or "hidden 1 dimensionality" picture for the CDW is confirmed very well by our direct image of the FS. K0.3MoO3, the so-called "blue bronze," is a quasi-1 dimensional (quasi-1D) CDW material. Even in its metallic phase above the CDW transition temperature, its photoemission spectra show an anomalously weak intensity at EF and no clear metallic Fermi edge. I compare predictions of an LL model and a CDW fluctuation model regarding these aspects, and find that the LL scenario explains them better. Despite the weak EF intensity, the EF intensity map shows a FS pattern in good agreement with the expected FS and the known CDW wavevector. Li0.9Mo6O17 is a quasi-1D material, whose 24 K transition is incompatible with a CDW transition. I compare the 200 K ARPES lineshapes with the LL lineshapes calculated using the spin-independent Tomonaga-Luttinger model. I point out both strong similarities and some significant differences. (Abstract shortened by UMI.)

  9. Positron excitation of neon

    NASA Technical Reports Server (NTRS)

    Parcell, L. A.; Mceachran, R. P.; Stauffer, A. D.

    1990-01-01

    The differential and total cross section for the excitation of the 3s1P10 and 3p1P1 states of neon by positron impact were calculated using a distorted-wave approximation. The results agree well with experimental conclusions.

  10. Exploring Excited Hadrons

    E-print Network

    Colin Morningstar

    2008-10-24

    Progress in extracting the spectrum of excited hadron resonances is reviewed and the key issues and challenges in such computations are outlined. The importance of multi-hadron states as simulations are done with lighter pion masses is discussed, and the need for all-to-all quark propagators is emphasized.

  11. Physics of liquid jets

    NASA Astrophysics Data System (ADS)

    Eggers, Jens; Villermaux, Emmanuel

    2008-03-01

    Jets, i.e. collimated streams of matter, occur from the microscale up to the large-scale structure of the universe. Our focus will be mostly on surface tension effects, which result from the cohesive properties of liquids. Paradoxically, cohesive forces promote the breakup of jets, widely encountered in nature, technology and basic science, for example in nuclear fission, DNA sampling, medical diagnostics, sprays, agricultural irrigation and jet engine technology. Liquid jets thus serve as a paradigm for free-surface motion, hydrodynamic instability and singularity formation leading to drop breakup. In addition to their practical usefulness, jets are an ideal probe for liquid properties, such as surface tension, viscosity or non-Newtonian rheology. They also arise from the last but one topology change of liquid masses bursting into sprays. Jet dynamics are sensitive to the turbulent or thermal excitation of the fluid, as well as to the surrounding gas or fluid medium. The aim of this review is to provide a unified description of the fundamental and the technological aspects of these subjects.

  12. Coalescence of Liquid Drops

    NASA Technical Reports Server (NTRS)

    Yao, Wei-Jun

    2003-01-01

    When two liquid drops come into contact, a neck forms between them and grows rapidly. We are interested in the very early stage of the coalescence process, which can be characterized by the time dependence of the radius of the neck. The functional dependence of the size of the neck on time depends on the properties of the liquid. Experimentally, we are investigating a liquid in Stokes flow regime where the viscosity provides the principal retarding force to the surface tension. Recently, it has been predicted that the neck radius should change as t ln|t| in this regime. Theoretically, we have studied the situation when the velocity at each point on the surface is proportional to the local curvature and directed normal to the surface. This is the case that should be applicable to superfluid helium at low temperature when the mean free path of the thermal excitations are comparable to the size of liquid drops. For this system, the radius of the neck is found to be proportional to t(sup 1/3). We are able to find a simple expression for the shape of the interface in the vicinity of the neck.

  13. Liquid Metals

    NASA Astrophysics Data System (ADS)

    March, Norman Henry

    1990-10-01

    This comprehensive, research level introduction to the theory of liquid metals presents the concepts needed to understand the properties of these metals starting with a survey of the basic experimental facts. The quantitative theory of liquid pair correlation functions, effective ion-ion interactions, thermodynamic properties and electronic and atomic transport is then developed. The book also explores inelastic neutron scattering from bulk liquid metals, critical behavior, magnetism, the present understanding of the liquid metal surface, binary liquid metals, shock wave studies, liquid hydrogen plasmas and the constitution of red star giants. This is an informative text for advanced postgraduate students and researchers in condensed matter physics, theoretical physics, physical chemistry and theoretical chemistry.

  14. Heat capacity of liquids: An approach from the solid phase

    NASA Astrophysics Data System (ADS)

    Trachenko, Kostya

    2008-09-01

    We calculate the energy and heat capacity of a liquid on the basis of its elastic properties and vibrational states. The experimental decrease of liquid heat capacity with temperature is attributed to the increasing loss of two transverse modes with frequency ?<1/? , where ? is liquid relaxation time. In a simple model, liquid heat capacity is related to viscosity and is compared with the experimental data of mercury. We also calculate the vibrational energy of a quantum liquid, and show that transverse phonons cannot be excited in the low-temperature limit. Finally, we discuss the implications of the proposed approach to liquids for the problem of glass transition.

  15. The scintillation of liquid argon

    E-print Network

    Heindl, T; Hofmann, M; Krücken, R; Oberauer, L; Potzel, W; Wieser, J; Ulrich, A

    2015-01-01

    A spectroscopic study of liquid argon from the vacuum ultraviolet at 110 nm to 1000 nm is presented. Excitation was performed using continuous and pulsed 12 keV electron beams. The emission is dominated by the analogue of the so called 2nd excimer continuum. Various additional emission features were found. The time structure of the light emission has been measured for a set of well defined wavelength positions. The results help to interpret literature data in the context of liquid rare gas detectors in which the wavelength information is lost due to the use of wavelength shifters.

  16. Apparatus for photon excited catalysis

    NASA Technical Reports Server (NTRS)

    Saffren, M. M. (inventor)

    1977-01-01

    An apparatus is described for increasing the yield of photonically excited gas phase reactions by extracting excess energy from unstable, excited species by contacting the species with the surface of a finely divided solid.

  17. Harmonically excited orbital variations

    SciTech Connect

    Morgan, T.

    1985-08-06

    Rephrasing the equations of motion for orbital maneuvers in terms of Lagrangian generalized coordinates instead of Newtonian rectangular cartesian coordinates can make certain harmonic terms in the orbital angular momentum vector more readily apparent. In this formulation the equations of motion adopt the form of a damped harmonic oscillator when torques are applied to the orbit in a variationally prescribed manner. The frequencies of the oscillator equation are in some ways unexpected but can nonetheless be exploited through resonant forcing functions to achieve large secular variations in the orbital elements. Two cases are discussed using a circular orbit as the control case: (1) large changes in orbital inclination achieved by harmonic excitation rather than one impulsive velocity change, and (2) periodic and secular changes to the longitude of the ascending node using both stable and unstable excitation strategies. The implications of these equations are also discussed for both artificial satellites and natural satellites. For the former, two utilitarian orbits are suggested, each exploiting a form of harmonic excitation. 5 refs.

  18. Brain Excitability in Stroke

    PubMed Central

    Carmichael, S. Thomas

    2015-01-01

    There is no current medical therapy for stroke recovery. Principles of physiological plasticity have been identified during recovery in both animal models and human stroke. Stroke produces a loss of physiological brain maps in adjacent peri-infarct cortex and then a remapping of motor and sensory functions in this region. This remapping of function in peri-infarct cortex correlates closely with recovery. Recent studies have shown that the stroke produces abnormal conditions of excitability in neuronal circuits adjacent to the infarct that may be the substrate for this process of brain remapping and recovery. Stroke causes a hypo-excitability in peri-infarct motor cortex that stems from increased tonic ?-aminobutyric acid activity onto neurons. Drugs that reverse this ?-aminobutyric acid signaling promote recovery after stroke. Stroke also increases the sensitivity of glutamate receptor signaling in peri-infarct cortex well after the stroke event, and stimulating ?-amino-3-hydroxyl-5-methyl-4-isoxazole-propionate glutamate receptors in peri-infarct cortex promotes recovery after stroke. Both blocking tonic ?-aminobutyric acid currents and stimulating ?-amino-3-hydroxyl-5-methyl-4-isoxazole-propionate receptors promote recovery after stroke when initiated at quite a delay, more than 3 to 5 days after the infarct. These changes in the excitability of neuronal circuits in peri-infarct cortex after stroke may underlie the process of remapping motor and sensory function after stroke and may identify new therapeutic targets to promote stroke recovery. PMID:21987395

  19. Holes in a Quantum Spin Liquid.

    PubMed

    Xu; Aeppli; Bisher; Broholm; DiTusa; Frost; Ito; Oka; Paul; Takagi; Treacy

    2000-07-21

    Magnetic neutron scattering provides evidence for nucleation of antiferromagnetic droplets around impurities in a doped nickel oxide-based quantum magnet. The undoped parent compound contains a spin liquid with a cooperative singlet ground state and a gap in the magnetic excitation spectrum. Calcium doping creates excitations below the gap with an incommensurate structure factor. We show that weakly interacting antiferromagnetic droplets with a central phase shift of pi and a size controlled by the correlation length of the quantum liquid can account for the data. The experiment provides a quantitative impression of the magnetic polarization cloud associated with holes in a doped transition metal oxide. PMID:10903195

  20. Double Excitations of Helium

    NASA Astrophysics Data System (ADS)

    Menzel, Alexander

    1996-05-01

    The double excitations of helium offer an ideal case for investigating electron dynamics in a three-body system. Our study of the He ^1P^o double excitations comprises measurements of the partial photoionization cross sections ?n (He^+) and the partial photoelectron angular distribution parameters ?n for the series N(K,T)^Ai up to the N=5 threshold. The experiment was performed at the ALS undulator beam line 9.0.1., which provided a photon flux of 2 × 10^12 photons per second with a small photon energy bandpass of 7 to 12 meV. This level of differentiation, along with the small bandpass, offers the most critical assessment of the dynamics of the two-electron excitations to date. The principal series K=N-2 are clearly delineated in both ?n and ?_n. The ?n show all minor series with N=K-4 very clearly, in contrast to measurements of the total absorption cross section, as well as very weak members with A=-1. Excellent accord between experiment and theory, particularly the hyperspherical close-coupling method, was found for the dynamic properties in all instances, including the interference pattern due to an overlap of N=5 and N=6 series members. Generally, the Rydberg series of resonance-induced profiles vary greatly depending on the final ionic state He^+(n), whereas the peak-to-valley variation in the ?n within a given series N is of similar magnitude for all n. Interestingly, a striking systematic trend is noted through the various series: the resonance-induced profiles for both the ?n and ?n of the photoelectron satellites are virtually identical provided the final ionic state He^+(n), n >= 2, is reached via an excited series N with ?=1, or ?=2, where ?=N-n. This overall pattern might be attributed to the general similarity of states with the same set of approximately good quantum numbers (N-K), A, and T. We tentatively propose an extension of these systematics for higher series N >= 5, although further theoretical work toward understanding these features of the doubly excited states will be needed. The experiment was performed in close collaboration with C.D. Caldwell, M.O. Krause, S.P. Frigo, and S.B. Whitfield. Valuable theoretical contributions were made by J.-Z. Tang and I. Shimamura. Part of the work appeared in Phys. Rev. Lett. 75, 1479 (1995). This work is supported by the National Science Foundation under grants PHY-9207634 and PHY-9507573.

  1. Ultrafast conversions between hydrogen bonded structures in liquid water observed by femtosecond x-ray spectroscopy

    E-print Network

    in living organisms exploit and depend on the un- usual properties of water. Liquid water can be regardedUltrafast conversions between hydrogen bonded structures in liquid water observed by femtosecond x bond structures in water via core-hole excitation. The oxygen K-edge of vibrationally excited water

  2. Liquid metal thermoacoustic engine

    SciTech Connect

    Swift, G.W.; Migliori, A.; Wheatley, J.C.

    1986-01-01

    We are studying a liquid metal thermoacoustic engine both theoretically and experimentally. This type of engine promises to produce large quantities of electrical energy from heat at modest efficiency with no moving parts. A sound wave is usually thought of as consisting of pressure oscillations, but always attendant to the pressure oscillation are temperature oscillations. The combination produces a rich variety of ''thermoacoustic'' effects. These effects are usually so small that they are never noticed in everyday life; nevertheless under the right circumstances they can be harnessed to produce powerful heat engines, heat pumps, and refrigerators. In our liquid metal thermoacoustic engine, heat flow from a high temperature source to a low temperature sink generates a high-amplitude standing acoustic wave in liquid sodium. This acoustic power is converted to electric power by a simple magnetohydrodynamic effect at the acoustic oscillation frequency. We have developed a detailed thermoacoustic theory applicable to this engine, and find that a reasonably designed liquid sodium engine operating between 700/sup 0/C and 100/sup 0/C should generate about 60 W/cm/sup 2/ of acoustic power at about 1/3 of Carnot's efficiency. Construction of a 3000 W-thermal laboratory model engine has just been completed, and we have exciting preliminary experimental results as of the time of preparation of this manuscript showing, basically, that the engine works. We have also designed and built a 1 kHz liquid sodium magnetohydrodynamic generator and have extensive measurements on it. It is now very well characterized both experimentally and theoretically. The first generator of its kind, it already converts acoustic power to electric power with 40% efficiency. 16 refs., 5 figs.

  3. CellExcite: an efficient simulation environment for excitable cells

    PubMed Central

    Bartocci, Ezio; Corradini, Flavio; Entcheva, Emilia; Grosu, Radu; Smolka, Scott A

    2008-01-01

    Background Brain, heart and skeletal muscle share similar properties of excitable tissue, featuring both discrete behavior (all-or-nothing response to electrical activation) and continuous behavior (recovery to rest follows a temporal path, determined by multiple competing ion flows). Classical mathematical models of excitable cells involve complex systems of nonlinear differential equations. Such models not only impair formal analysis but also impose high computational demands on simulations, especially in large-scale 2-D and 3-D cell networks. In this paper, we show that by choosing Hybrid Automata as the modeling formalism, it is possible to construct a more abstract model of excitable cells that preserves the properties of interest while reducing the computational effort, thereby admitting the possibility of formal analysis and efficient simulation. Results We have developed CellExcite, a sophisticated simulation environment for excitable-cell networks. CellExcite allows the user to sketch a tissue of excitable cells, plan the stimuli to be applied during simulation, and customize the diffusion model. CellExcite adopts Hybrid Automata (HA) as the computational model in order to efficiently capture both discrete and continuous excitable-cell behavior. Conclusions The CellExcite simulation framework for multicellular HA arrays exhibits significantly improved computational efficiency in large-scale simulations, thus opening the possibility for formal analysis based on HA theory. A demo of CellExcite is available at . PMID:18387205

  4. Liquid pearls

    E-print Network

    Bremond, Nicolas; Bibette, Jérôme

    2010-01-01

    This fluid dynamics video reports how to form liquid core capsules having a thin hydrogel elastic membrane named liquid pearls. These fish-egg like structures are initially made of a millimetric liquid drop, aqueous or not, coated with an aqueous liquid film containing sodium alginate that gels once the double drop enters a calcium chloride bath. The creation of such pearls with micrometer thick membrane requires to suppress mixing until gelling takes place. Here, we show that superimposing a two dimensional surfactant precipitation at the interface confers a transient rigidity that can damp the shear induced instability at impact. Based on this, pearls containing almost any type of liquids can be created. The video focuses on the dynamics of the entry of the compound drop into the gelling bath.

  5. Get excited: reappraising pre-performance anxiety as excitement.

    PubMed

    Brooks, Alison Wood

    2014-06-01

    Individuals often feel anxious in anticipation of tasks such as speaking in public or meeting with a boss. I find that an overwhelming majority of people believe trying to calm down is the best way to cope with pre-performance anxiety. However, across several studies involving karaoke singing, public speaking, and math performance, I investigate an alternative strategy: reappraising anxiety as excitement. Compared with those who attempt to calm down, individuals who reappraise their anxious arousal as excitement feel more excited and perform better. Individuals can reappraise anxiety as excitement using minimal strategies such as self-talk (e.g., saying "I am excited" out loud) or simple messages (e.g., "get excited"), which lead them to feel more excited, adopt an opportunity mind-set (as opposed to a threat mind-set), and improve their subsequent performance. These findings suggest the importance of arousal congruency during the emotional reappraisal process. PMID:24364682

  6. Vacuum ultraviolet excitation luminescence spectroscopy of few-layered MoS2.

    PubMed

    Pankratov, V; Hoszowska, J; Dousse, J-Cl; Huttula, M; Kis, A; Krasnozhon, D; Zhang, M; Cao, W

    2016-01-13

    We report on vacuum ultraviolet (VUV) excited photoluminescence (PL) spectra emitted from a chemical vapor deposited MoS2 few-layered film. The excitation spectrum was recorded by monitoring intensities of PL spectra at ~1.9?eV. A strong wide excitation band peaking at 7?eV was found in the excitation. The PL excitation band is most intensive at liquid helium temperature and completely quenched at 100?K. Through first-principles calculations of photoabsorption in MoS2, the excitation was explicated and attributed to transitions of electrons from p- and d- type states in the valence band to the d- and p-type states in the conduction band. The obtained photon-in/photon-out results clarify the excitation and emission behavior of the low dimensional MoS2 when interacting with the VUV light sources. PMID:26648394

  7. Multiphonon excitations in boson quantum films

    SciTech Connect

    Clements, B.E.; Krotscheck, E.; Tymczak, C.J.

    1996-05-01

    Dynamical excitations in thin liquid films of {sup 4}He adsorbed to a substrate are investigated by using a microscopic theory of excitations that includes multiple-phonon scattering. We study the dispersion relation, excitation mechanisms, transition densities, and particle currents as a function of surface coverage. A primary new result is that we have included three-phonon scattering processes in the calculation of the dynamic structure function and the one-body current densities. With the exception that our ground state is determined by our variational theory, rather than taken from experiment, our work on the dynamic structure function is the generalization of that of Jackson [Phys. Rev. A {bold 4}, 2386 (1971)] to inhomogeneous systems (films). Using sum rules for the dynamic structure function as a guide, we suggest a simple scaling argument for improving the agreement between our dynamic structure function and the experimental one. The addition of three-phonon contributions bring about the following changes. First, the energy of most modes is lowered by a non-negligible amount for finite momentum excitations. Second, the film{close_quote}s surface mode is the exception; it is only slightly affected. Third, for monolayer films there is large scattering at high energies at intermediate values of momenta. This scattering can be traced back to an anomalously large contribution to the two-particle density of states. Fourth, all modes with energy above a critical energy decay, and the associated peaks of the dynamic structure function are broadened. Fifth, the maxonlike character is enhanced in the bulklike modes. {copyright} {ital 1996 The American Physical Society.}

  8. Excitability in Dictyostelium development

    NASA Astrophysics Data System (ADS)

    Schwab, David

    2013-03-01

    Discovering how populations of cells reliably develop into complex multi-cellular structures is a key challenge in modern developmental biology. This requires an understanding of how networks at the single-cell level, when combined with intercellular signaling and environmental cues, give rise to the collective behaviors observed in cellular populations. I will present work in collaboration with the Gregor lab, showing that the signal-relay response of starved cells of the amoebae Dictyostelium discoideum can be well modeled as an excitable system. This is in contrast to existing models of the network that postulate a feed-forward cascade. I then extend the signal-relay model to describe how spatial gradient sensing may be achieved via excitability. One potential advantage of relying on feedback for gradient sensing is in preventing ``cheaters'' that do not produce signals from taking over the population. I then combine these models of single-cell signaling and chemotaxis to perform large-scale agent-based simulations of aggregating populations. This allows direct study of how variations in single-cell dynamics modify population behavior. In order to further test this model, I use the results of a screen for mutant cell lines that exhibit altered collective patterns. Finally, I use an existing FRET movie database of starved cell populations at varying cell densities and dilution rates to study heterogeneity in repeated spatio-temporal activity patterns.

  9. Liquid Bridge

    NASA Technical Reports Server (NTRS)

    1996-01-01

    Crystal Growth in magnetic fields, a float-zone sample, the surface tension of the melt keeps the sample suspended between the sample rods in the furnace forming an actual liquid bridge. Principal Investigator: Dr. Frank Szofran

  10. Neural Excitability and Singular Bifurcations.

    PubMed

    De Maesschalck, Peter; Wechselberger, Martin

    2015-12-01

    We discuss the notion of excitability in 2D slow/fast neural models from a geometric singular perturbation theory point of view. We focus on the inherent singular nature of slow/fast neural models and define excitability via singular bifurcations. In particular, we show that type I excitability is associated with a novel singular Bogdanov-Takens/SNIC bifurcation while type II excitability is associated with a singular Andronov-Hopf bifurcation. In both cases, canards play an important role in the understanding of the unfolding of these singular bifurcation structures. We also explain the transition between the two excitability types and highlight all bifurcations involved, thus providing a complete analysis of excitability based on geometric singular perturbation theory. PMID:26246435

  11. Fusion excitation function revisited

    E-print Network

    Ph. Eudes; Z. Basrak; F. Sébille; V. de la Mota; G. Royer; M. Zori?

    2012-09-28

    We report on a comprehensive systematics of fusion-evaporation and/or fusion-fission cross sections for a very large variety of systems over an energy range 4-155 A.MeV. Scaled by the reaction cross sections, fusion cross sections do not show a universal behavior valid for all systems although a high degree of correlation is present when data are ordered by the system mass asymmetry.For the rather light and close to mass-symmetric systems the main characteristics of the complete and incomplete fusion excitation functions can be precisely determined. Despite an evident lack of data above 15A.MeV for all heavy systems the available data suggests that geometrical effects could explain the persistence of incomplete fusion at incident energies as high as 155A.MeV.

  12. Nuclear collective excitations in a two-phase coexistence region

    SciTech Connect

    Aguirre, R. M.; De Paoli, A. L.

    2011-04-15

    The relation between collective modes and phase transitions in nuclear matter is examined. The dispersion relations for the low-lying excitations in a linear approach are evaluated within a Landau-Fermi liquid scheme by assuming coexisting phases in thermodynamical equilibrium. Temperature and isospin composition are used as relevant parameters. The in-medium nuclear interaction is provided by a recently proposed density functional model. The low density liquid-gas phase transition is taken as a typical situation for examination. We found significative modifications in the energy spectrum, within a certain range of temperatures and isospin asymmetry, due to the separation of matter into independent phases. The influence of the electromagnetic interaction over the dispersion relation of these collective excitations is also examined.

  13. Fission and Nuclear Liquid-Gas Phase Transition

    E-print Network

    E. A. Cherepanov; V. A. Karnaukhov

    2007-03-30

    The temperature dependence of the liquid-drop fission barrier is considered, the critical temperature for the liquid-gas phase transition in nuclear matter being a parameter. Experimental and calculated data on the fission probability are compared for highly excited $^{188}$Os. The calculations have been made in the framework of the statistical model. It is concluded that the critical temperature for the nuclear liquid--gas phase transition is higher than 16 MeV.

  14. Optically excited states in positronium

    NASA Technical Reports Server (NTRS)

    Howell, R. H.; Ziock, Klaus P.; Magnotta, F.; Dermer, Charles D.; Failor, R. A.; Jones, K. M.

    1990-01-01

    Optical excitation are reported of the 1 3S-2 3P transition in positronium, and a second excitation from n=2 to higher n states. The experiment used light from two pulsed dye lasers. Changes in the positronium annihilation rate during and after the laser pulse were used to deduce the excited state populations. The n=2 level was found to be saturable and excitable to a substantial fraction of n=2 positronium to higher levels. Preliminary spectroscopic measurements were performed on n=14 and n=15 positronium.

  15. Pattern Formation in Excitable Media

    NASA Astrophysics Data System (ADS)

    Reynolds, William Nash

    1992-01-01

    The phenomenon of excitability is observed in a wide variety of physical and biological systems. In this work, spatially extended excitable systems are examined from several different perspectives. First, a pedagogical introduction is used to motivate the derivation of the dynamics of one dimensional excitable pulses. In the second part, coupled map techniques for numerical simulation of excitable media and other interfacial systems are described. Examples are given for both excitable media and crystal growth. The third chapter addresses the phenomenon of spiral formation in excitable media. Exact rotating solutions are found for a class of models of excitable media. The solutions consist of two regions: an outer region, consisting of the spiral proper, which exhibits a singularity at its tip, and the core region, obtained by rescaling space in the vicinity of the tip. The tip singularity is resolved in the core region, leading to a consistent solution in all of space. The stability of both the spiral and the core is investigated, with the result that the spiral is found to be stable, and the core unstable. Finally, the stability of excitable waves of the chemical cAMP traveling over aggregating colonies of the slime mold Dictyostelium discoideum is examined by coupling the excitable dynamics of the cAMP signalling system to a simple model of chemotaxis, with result that cellular motion is found to destabilize the waves, causing the initially uniform field of cells to break up into streams.

  16. Formation and Observation of a Quasi-Two-Dimensional dx y Electron Liquid in Epitaxially Stabilized Sr2 -xLax TiO4 Thin Films

    NASA Astrophysics Data System (ADS)

    Nie, Y. F.; Di Sante, D.; Chatterjee, S.; King, P. D. C.; Uchida, M.; Ciuchi, S.; Schlom, D. G.; Shen, K. M.

    2015-08-01

    We report the formation and observation of an electron liquid in Sr2 -xLax TiO4 , the quasi-two-dimensional counterpart of SrTiO3 , through reactive molecular-beam epitaxy and in situ angle-resolved photoemission spectroscopy. The lowest lying states are found to be comprised of Ti 3 dx y orbitals, analogous to the LaAlO3/SrTiO3 interface and exhibit unusually broad features characterized by quantized energy levels and a reduced Luttinger volume. Using model calculations, we explain these characteristics through an interplay of disorder and electron-phonon coupling acting cooperatively at similar energy scales, which provides a possible mechanism for explaining the low free carrier concentrations observed at various oxide heterostructures such as the LaAlO3/SrTiO3 interface.

  17. Liquid Crystals

    NASA Technical Reports Server (NTRS)

    1990-01-01

    Thermochromic liquid crystals, or TLCs, are a type of liquid crystals that react to changes in temperature by changing color. The Hallcrest/NASA collaboration involved development of a new way to visualize boundary layer transition in flight and in wind tunnel testing of aircraft wing and body surfaces. TLCs offered a new and potentially better method of visualizing the boundary layer transition in flight. Hallcrest provided a liquid crystal formulation technique that afforded great control over the sensitivity of the liquid crystals to varying conditions. Method is of great use to industry, government and universities for aerodynamic and hydrodynamic testing. Company's principal line is temperature indicating devices for industrial use, such as non-destructive testing and flaw detection in electric/electronic systems, medical application, such as diagnostic systems, for retail sale, such as room, refrigerator, baby bath and aquarium thermometers, and for advertising and promotion specials. Additionally, Hallcrest manufactures TLC mixtures for cosmetic applications, and liquid crystal battery tester for Duracell batteries.

  18. Multiple exciton generation and singlet fission: the role of collective effects

    NASA Astrophysics Data System (ADS)

    Eaves, Joel; Sweeney, Mark; Teichen, Paul; Strong, Steven

    2014-03-01

    Materials that relax to multiply excited states present exciting possibilities for overcoming the Shockley-Queisser limit in photovoltaic devices. For an excited electronic state to relax in this manner, electron-electron couplings must be strong relative to electron-phonon couplings. In this talk, I will discuss some ways in which these criteria may be met. I will discuss our work on multiple exciton generation in single-walled carbon nanotubes using Luttinger liquid theory and on singlet fission in molecular crystals using quantum exciton models. The Luttinger liquid theory focuses on the long wavelength part of the Coulomb interaction between electrons, and therefore allows us to assess the suspected role that dimensionality plays in enhancing electron-electron interactions. I will also discuss our results for quantum lattice models of singlet fission in molecular crystals that allows us to examine collective dynamical effects that contribute to efficient fission.

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

    E-print Network

    Neumark, Daniel M.

    Dynamics of electron solvation in methanol: Excited state relaxation and generation by charge (2015) Dynamics of electron solvation in methanol: Excited state relaxation and generation by charge of the solvated electron in methanol are studied by time-resolved photoelectron spectroscopy on a liquid methanol

  20. Macromolecular liquids

    SciTech Connect

    Safinya, C.R.; Safran, S.A. ); Pincus, P.A. )

    1990-01-01

    Liquids include a broad range of material systems which are of high scientific and technological interest. Generally speaking, these are partially ordered or disordered phases where the individual molecular species have organized themselves on length scales which are larger than simple fluids, typically between 10 Angstroms and several microns. The specific systems reported on in this book include membranes, microemulsions, micelles, liquid crystals, colloidal suspensions, and polymers. They have a major impact on a broad spectrum of technological industries such as displays, plastics, soap and detergents, chemicals and petroleum, and pharmaceuticals.

  1. Electroviscoelasticity of liquid/liquid interfaces: fractional-order model.

    PubMed

    Spasic, Aleksandar M; Lazarevic, Mihailo P

    2005-02-01

    A number of theories that describe the behavior of liquid-liquid interfaces have been developed and applied to various dispersed systems, e.g., Stokes, Reiner-Rivelin, Ericksen, Einstein, Smoluchowski, and Kinch. A new theory of electroviscoelasticity describes the behavior of electrified liquid-liquid interfaces in fine dispersed systems and is based on a new constitutive model of liquids. According to this model liquid-liquid droplet or droplet-film structure (collective of particles) is considered as a macroscopic system with internal structure determined by the way the molecules (ions) are tuned (structured) into the primary components of a cluster configuration. How the tuning/structuring occurs depends on the physical fields involved, both potential (elastic forces) and nonpotential (resistance forces). All these microelements of the primary structure can be considered as electromechanical oscillators assembled into groups, so that excitation by an external physical field may cause oscillations at the resonant/characteristic frequency of the system itself (coupling at the characteristic frequency). Up to now, three possible mathematical formalisms have been discussed related to the theory of electroviscoelasticity. The first is the tension tensor model, where the normal and tangential forces are considered, only in mathematical formalism, regardless of their origin (mechanical and/or electrical). The second is the Van der Pol derivative model, presented by linear and nonlinear differential equations. Finally, the third model presents an effort to generalize the previous Van der Pol equation: the ordinary time derivative and integral are now replaced with the corresponding fractional-order time derivative and integral of order p<1. PMID:15576102

  2. Excited waves in shear layers

    NASA Technical Reports Server (NTRS)

    Bechert, D. W.

    1982-01-01

    The generation of instability waves in free shear layers is investigated. The model assumes an infinitesimally thin shear layer shed from a semi-infinite plate which is exposed to sound excitation. The acoustical shear layer excitation by a source further away from the plate edge in the downstream direction is very weak while upstream from the plate edge the excitation is relatively efficient. A special solution is given for the source at the plate edge. The theory is then extended to two streams on both sides of the shear layer having different velocities and densities. Furthermore, the excitation of a shear layer in a channel is calculated. A reference quantity is found for the magnitude of the excited instability waves. For a comparison with measurements, numerical computations of the velocity field outside the shear layer were carried out.

  3. Vibrational excitation induces double reaction.

    PubMed

    Huang, Kai; Leung, Lydie; Lim, Tingbin; Ning, Zhanyu; Polanyi, John C

    2014-12-23

    Electron-induced reaction at metal surfaces is currently the subject of extensive study. Here, we broaden the range of experimentation to a comparison of vibrational excitation with electronic excitation, for reaction of the same molecule at the same clean metal surface. In a previous study of electron-induced reaction by scanning tunneling microscopy (STM), we examined the dynamics of the concurrent breaking of the two C-I bonds of ortho-diiodobenzene physisorbed on Cu(110). The energy of the incident electron was near the electronic excitation threshold of E0=1.0 eV required to induce this single-electron process. STM has been employed in the present work to study the reaction dynamics at the substantially lower incident electron energies of 0.3 eV, well below the electronic excitation threshold. The observed increase in reaction rate with current was found to be fourth-order, indicative of multistep reagent vibrational excitation, in contrast to the first-order rate dependence found earlier for electronic excitation. The change in mode of excitation was accompanied by altered reaction dynamics, evidenced by a different pattern of binding of the chemisorbed products to the copper surface. We have modeled these altered reaction dynamics by exciting normal modes of vibration that distort the C-I bonds of the physisorbed reagent. Using the same ab initio ground potential-energy surface as in the prior work on electronic excitation, but with only vibrational excitation of the physisorbed reagent in the asymmetric stretch mode of C-I bonds, we obtained the observed alteration in reaction dynamics. PMID:25489788

  4. Liquid ventilation.

    PubMed

    Sarkar, Suman; Paswan, Anil; Prakas, S

    2014-01-01

    Human have lungs to breathe air and they have no gills to breath liquids like fish. When the surface tension at the air-liquid interface of the lung increases as in acute lung injury, scientists started to think about filling the lung with fluid instead of air to reduce the surface tension and facilitate ventilation. Liquid ventilation (LV) is a technique of mechanical ventilation in which the lungs are insufflated with an oxygenated perfluorochemical liquid rather than an oxygen-containing gas mixture. The use of perfluorochemicals, rather than nitrogen as the inert carrier of oxygen and carbon dioxide offers a number of advantages for the treatment of acute lung injury. In addition, there are non-respiratory applications with expanding potential including pulmonary drug delivery and radiographic imaging. It is well-known that respiratory diseases are one of the most common causes of morbidity and mortality in intensive care unit. During the past few years several new modalities of treatment have been introduced. One of them and probably the most fascinating, is of LV. Partial LV, on which much of the existing research has concentrated, requires partial filling of lungs with perfluorocarbons (PFC's) and ventilation with gas tidal volumes using conventional mechanical ventilators. Various physico-chemical properties of PFC's make them the ideal media. It results in a dramatic improvement in lung compliance and oxygenation and decline in mean airway pressure and oxygen requirements. No long-term side-effect reported. PMID:25886321

  5. Industrial applications of photonuclear resonance excitation

    E-print Network

    Chichester, David Lee, 1971-

    2000-01-01

    Photonuclear resonance excitation refers to a variety of photonuclear interaction processes that lead to the excitation of a nucleus from some initial state to a higher energy nuclear state. Typical excited nuclear state ...

  6. 46 CFR 111.12-3 - Excitation.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...ELECTRICAL ENGINEERING ELECTRIC SYSTEMS-GENERAL REQUIREMENTS Generator Construction and Circuits § 111.12-3 Excitation...no static exciter may be used for excitation of an emergency generator unless it is provided with a permanent magnet or a...

  7. Liquid electrode

    DOEpatents

    Ekechukwu, Amy A. (Augusta, GA)

    1994-01-01

    A dropping electrolyte electrode for use in electrochemical analysis of non-polar sample solutions, such as benzene or cyclohexane. The liquid electrode, preferably an aqueous salt solution immiscible in the sample solution, is introduced into the solution in dropwise fashion from a capillary. The electrolyte is introduced at a known rate, thus, the droplets each have the same volume and surface area. The electrode is used in making standard electrochemical measurements in order to determine properties of non-polar sample solutions.

  8. Parametric Excitation of a DWSC 

    E-print Network

    Lakhotia, Chandan

    2011-08-08

    Parametric excitation of the DWSC (Deep Water Stable Craneship) is studied in this thesis. It occurs for a system without any external forcing, when one of the coefficients in the equation of motion (EOM) modeling the system varies with time...

  9. Exciting Polaritons with Quantum Light

    NASA Astrophysics Data System (ADS)

    López Carreño, J. C.; Sánchez Muñoz, C.; Sanvitto, D.; del Valle, E.; Laussy, F. P.

    2015-11-01

    We discuss the excitation of polaritons—strongly coupled states of light and matter—by quantum light, instead of the usual laser or thermal excitation. As one illustration of the new horizons thus opened, we introduce "Mollow spectroscopy"—a theoretical concept for a spectroscopic technique that consists of scanning the output of resonance fluorescence onto an optical target—from which weak nonlinearities can be read with high precision even in strongly dissipative environments.

  10. Laser-induced nuclear excitation

    SciTech Connect

    Zon, B. A. Kornev, A. S.

    2010-05-15

    An analysis is presented of the Coulomb excitation of low-lying nuclear levels by the electrons produced by strong-field ionization of atoms. It is shown that the resulting short-lived radioactivity can be as high as on the order of 10{sup 3} Ci for certain isotopes excited by using modern laser systems. Relativistic effects are demonstrated that substantially increase radioactivity as compared to that predicted by nonrelativistic theory results.

  11. Heat capacity of liquids: an approach from the solid phase

    E-print Network

    Kostya Trachenko

    2008-08-20

    We calculate the energy and heat capacity of a liquid on the basis of its elastic properties and vibrational states. The experimental decrease of liquid heat capacity with temperature is attributed to the increasing loss of two transverse modes with frequency $\\omegamercury. We also calculate the vibrational energy of a quantum liquid, and show that transverse phonons can not be excited in the low-temperature limit. Finally, we discuss the implications of the proposed approach to liquids for the problem of glass transition.

  12. Electron-excited molecule interactions

    SciTech Connect

    Christophorou, L.G. Tennessee Univ., Knoxville, TN . Dept. of Physics)

    1991-01-01

    In this paper the limited but significant knowledge to date on electron scattering from vibrationally/rotationally excited molecules and electron scattering from and electron impact ionization of electronically excited molecules is briefly summarized and discussed. The profound effects of the internal energy content of a molecule on its electron attachment properties are highlighted focusing in particular on electron attachment to vibrationally/rotationally and to electronically excited molecules. The limited knowledge to date on electron-excited molecule interactions clearly shows that the cross sections for certain electron-molecule collision processes can be very different from those involving ground state molecules. For example, optically enhanced electron attachment studies have shown that electron attachment to electronically excited molecules can occur with cross sections 10{sup 6} to 10{sup 7} times larger compared to ground state molecules. The study of electron-excited molecule interactions offers many experimental and theoretical challenges and opportunities and is both of fundamental and technological significance. 54 refs., 15 figs.

  13. Redox Control of Cardiac Excitability

    PubMed Central

    Aggarwal, Nitin T.

    2013-01-01

    Abstract Reactive oxygen species (ROS) have been associated with various human diseases, and considerable attention has been paid to investigate their physiological effects. Various ROS are synthesized in the mitochondria and accumulate in the cytoplasm if the cellular antioxidant defense mechanism fails. The critical balance of this ROS synthesis and antioxidant defense systems is termed the redox system of the cell. Various cardiovascular diseases have also been affected by redox to different degrees. ROS have been indicated as both detrimental and protective, via different cellular pathways, for cardiac myocyte functions, electrophysiology, and pharmacology. Mostly, the ROS functions depend on the type and amount of ROS synthesized. While the literature clearly indicates ROS effects on cardiac contractility, their effects on cardiac excitability are relatively under appreciated. Cardiac excitability depends on the functions of various cardiac sarcolemal or mitochondrial ion channels carrying various depolarizing or repolarizing currents that also maintain cellular ionic homeostasis. ROS alter the functions of these ion channels to various degrees to determine excitability by affecting the cellular resting potential and the morphology of the cardiac action potential. Thus, redox balance regulates cardiac excitability, and under pathological regulation, may alter action potential propagation to cause arrhythmia. Understanding how redox affects cellular excitability may lead to potential prophylaxis or treatment for various arrhythmias. This review will focus on the studies of redox and cardiac excitation. Antioxid. Redox Signal. 18, 432–468. PMID:22897788

  14. Simplex Z_2 spin liquids on the Kagome lattice with Entangled Pair States: spinon and vison coherence lengths, topological entropy and gapless edge modes

    E-print Network

    Didier Poilblanc; Norbert Schuch

    2013-03-30

    Gapped Z_2 spin liquids have been proposed as candidates for the ground-state of the S=1/2 quantum antiferromagnet on the Kagome lattice. We extend the use of Projected Entangled Pair States to construct (on the cylinder)Resonating Valence Bond (RVB) states including both nearest-neighbor and next-nearest neighbor singlet bonds. Our ansatz -- dubbed "simplex spin liquid" -- allows for an asymmetry between the two types of triangles (of order 2-3% in the energy density after optimization) leading to the breaking of inversion symmetry. We show that the topological Z_2 structure is still preserved and, by considering the presence or the absence of spinon and vison lines along an infinite cylinder, we explicitly construct four orthogonal RVB Minimally Entangled States. The spinon and vison coherence lengths are extracted from a finite size scaling w.r.t the cylinder perimeter of the energy splittings of the four sectors and are found to be of the order of the lattice spacing. The entanglement spectrum of a partitioned (infinite) cylinder is found to be gapless suggesting the occurrence, on a cylinder with {\\it real} open boundaries, of gapless edge modes formally similar to Luttinger liquid (non-chiral) spin and charge modes. When inversion symmetry is spontaneously broken, the RVB spin liquid exhibits an extra Ising degeneracy, which might have been observed in recent exact diagonalisation studies.

  15. Ultralow detection limits for an organic dye determined by fluorescence spectroscopy with laser diode excitation

    SciTech Connect

    Johnson, P.A.; Barber, T.E.; Smith, B.W.; Winefordner, J.D. )

    1989-04-15

    Fluorescence of IR-140, a laser dye in methanol solution, is excited by a semiconductor laser diode. Analytical figures of merit are compared for three different instrumental configurations, with the dye measured in a cuvette, a liquid jet, and a compact instrument. The best limit of detection, 46,000 molecules, was achieved with a liquid jet. Linear dynamic range was 6 orders of magnitude. The laser diode operates in the near-infrared region, resulting in low background fluorescence.

  16. Laser-induced separation of hydrogen isotopes in the liquid phase

    DOEpatents

    Freund, Samuel M. (Los Alamos, NM); Maier, II, William B. (Los Alamos, NM); Beattie, Willard H. (Los Alamos, NM); Holland, Redus F. (Los Alamos, NM)

    1980-01-01

    Hydrogen isotope separation is achieved by either (a) dissolving a hydrogen-bearing feedstock compound in a liquid solvent, or (b) liquefying a hydrogen-bearing feedstock compound, the liquid phase thus resulting being kept at a temperature at which spectral features of the feedstock relating to a particular hydrogen isotope are resolved, i.e., a clear-cut isotope shift is delineated, irradiating the liquid phase with monochromatic radiation of a wavelength which at least preferentially excites those molecules of the feedstock containing a first hydrogen isotope, inducing photochemical reaction in the excited molecules, and separating the reaction product containing the first isotope from the liquid phase.

  17. Liquid electrode

    DOEpatents

    Ekechukwu, A.A.

    1994-07-05

    A dropping electrolyte electrode is described for use in electrochemical analysis of non-polar sample solutions, such as benzene or cyclohexane. The liquid electrode, preferably an aqueous salt solution immiscible in the sample solution, is introduced into the solution in dropwise fashion from a capillary. The electrolyte is introduced at a known rate, thus, the droplets each have the same volume and surface area. The electrode is used in making standard electrochemical measurements in order to determine properties of non-polar sample solutions. 2 figures.

  18. High Average Power Laser Gain Medium With Low Optical Distortion Using A Transverse Flowing Liquid Host

    DOEpatents

    Comaskey, Brian J. (Walnut Creek, CA); Ault, Earl R. (Livermore, CA); Kuklo, Thomas C. (Oakdale, CA)

    2005-07-05

    A high average power, low optical distortion laser gain media is based on a flowing liquid media. A diode laser pumping device with tailored irradiance excites the laser active atom, ion or molecule within the liquid media. A laser active component of the liquid media exhibits energy storage times longer than or comparable to the thermal optical response time of the liquid. A circulation system that provides a closed loop for mixing and circulating the lasing liquid into and out of the optical cavity includes a pump, a diffuser, and a heat exchanger. A liquid flow gain cell includes flow straighteners and flow channel compression.

  19. X-ray reflectivity studies of liquid metal and alloy surfaces M. J. Regan* and P. S. Pershan

    E-print Network

    Pershan, Peter S.

    X-ray reflectivity studies of liquid metal and alloy surfaces M. J. Regan* and P. S. Pershan/vapor interface in liquid metals has been observed using x-ray reflectivity on sputtered clean surfaces under to suppress mechanically excited surface waves, the measurements were performed on thin liquid metal films ( 0

  20. 46 CFR 111.12-3 - Excitation.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... (incorporated by reference; see 46 CFR 110.10-1), except that those for mobile offshore drilling units must meet... 46 CFR 110.10-1). In particular, no static exciter may be used for excitation of an emergency... REQUIREMENTS Generator Construction and Circuits § 111.12-3 Excitation. In general, excitation must...

  1. 46 CFR 111.12-3 - Excitation.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... (incorporated by reference; see 46 CFR 110.10-1), except that those for mobile offshore drilling units must meet... 46 CFR 110.10-1). In particular, no static exciter may be used for excitation of an emergency... REQUIREMENTS Generator Construction and Circuits § 111.12-3 Excitation. In general, excitation must...

  2. 46 CFR 111.12-3 - Excitation.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... (incorporated by reference; see 46 CFR 110.10-1), except that those for mobile offshore drilling units must meet... 46 CFR 110.10-1). In particular, no static exciter may be used for excitation of an emergency... REQUIREMENTS Generator Construction and Circuits § 111.12-3 Excitation. In general, excitation must...

  3. 46 CFR 111.12-3 - Excitation.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... (incorporated by reference; see 46 CFR 110.10-1), except that those for mobile offshore drilling units must meet... 46 CFR 110.10-1). In particular, no static exciter may be used for excitation of an emergency... REQUIREMENTS Generator Construction and Circuits § 111.12-3 Excitation. In general, excitation must...

  4. 46 CFR 111.12-3 - Excitation.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... (incorporated by reference; see 46 CFR 110.10-1), except that those for mobile offshore drilling units must meet... 46 CFR 110.10-1). In particular, no static exciter may be used for excitation of an emergency... REQUIREMENTS Generator Construction and Circuits § 111.12-3 Excitation. In general, excitation must...

  5. Dynamics of Liquid ^4He in GelTek Silica

    NASA Astrophysics Data System (ADS)

    Plantevin, O.; Fåk, B.; Glyde, H. R.; Mulders, N.

    2000-03-01

    We present the first measurements of the excitations and dynamic structure factor, S(Q,?), of superfluid and normal liquid ^4He confined in GelTek Silica. GelTek is a 50% porous glass consisting of 25 Å diameter pores. The normal to superfluid transition temperature^1 of liquid ^4He at SVP in GelTek is T_c=725 mK. Up to approximately 50% filling of the GelTeK pores (estimated one complete solid layer on the pore walls), no excitations are observed. At 1.5 layers a broad excitation is observed which is identified with atom exchange between the solid and subsequent liquid layer. At fillings above 1.5 layers a phonon-roton (p-r) excitation is observed in the wavevector range investigated, 0.4 <= Q <= 2.2 ÅThe intensity in the p-r mode increases uniformly with further filling suggesting that all the ^4He beyond the first layer appears to be liquid. The temperature dependence of the weight of the single maxon-roton excitation in S(Q,?) does not scale with the superfluid density, ?_S(T), as it does in the bulk. A well defined mode exists above Tc where ?_S(T)=0 suggesting that a condensate may exist above T_c. These and other features will be discussed. ^1S. Miyamoto and Y. Takano, Czech J. Phys. 46 (suppl. S1), 137 (1996). The assistance of Y. Takano is gratefully acknowledged.

  6. Indirect excitation of ultrafast demagnetization.

    PubMed

    Vodungbo, Boris; Tudu, Bahrati; Perron, Jonathan; Delaunay, Renaud; Müller, Leonard; Berntsen, Magnus H; Grübel, Gerhard; Malinowski, Grégory; Weier, Christian; Gautier, Julien; Lambert, Guillaume; Zeitoun, Philippe; Gutt, Christian; Jal, Emmanuelle; Reid, Alexander H; Granitzka, Patrick W; Jaouen, Nicolas; Dakovski, Georgi L; Moeller, Stefan; Minitti, Michael P; Mitra, Ankush; Carron, Sebastian; Pfau, Bastian; von Korff Schmising, Clemens; Schneider, Michael; Eisebitt, Stefan; Lüning, Jan

    2016-01-01

    Does the excitation of ultrafast magnetization require direct interaction between the photons of the optical pump pulse and the magnetic layer? Here, we demonstrate unambiguously that this is not the case. For this we have studied the magnetization dynamics of a ferromagnetic cobalt/palladium multilayer capped by an IR-opaque aluminum layer. Upon excitation with an intense femtosecond-short IR laser pulse, the film exhibits the classical ultrafast demagnetization phenomenon although only a negligible number of IR photons penetrate the aluminum layer. In comparison with an uncapped cobalt/palladium reference film, the initial demagnetization of the capped film occurs with a delayed onset and at a slower rate. Both observations are qualitatively in line with energy transport from the aluminum layer into the underlying magnetic film by the excited, hot electrons of the aluminum film. Our data thus confirm recent theoretical predictions. PMID:26733106

  7. Excitation optimization for damage detection

    SciTech Connect

    Bement, Matthew T; Bewley, Thomas R

    2009-01-01

    A technique is developed to answer the important question: 'Given limited system response measurements and ever-present physical limits on the level of excitation, what excitation should be provided to a system to make damage most detectable?' Specifically, a method is presented for optimizing excitations that maximize the sensitivity of output measurements to perturbations in damage-related parameters estimated with an extended Kalman filter. This optimization is carried out in a computationally efficient manner using adjoint-based optimization and causes the innovations term in the extended Kalman filter to be larger in the presence of estimation errors, which leads to a better estimate of the damage-related parameters in question. The technique is demonstrated numerically on a nonlinear 2 DOF system, where a significant improvement in the damage-related parameter estimation is observed.

  8. Neutron star structure and collective excitations of finite nuclei

    NASA Astrophysics Data System (ADS)

    Paar, N.; Moustakidis, Ch. C.; Marketin, T.; Vretenar, D.; Lalazissis, G. A.

    2014-07-01

    A method is introduced that establishes relations between properties of collective excitations in finite nuclei and the phase transition density nt and pressure Pt at the inner edge separating the liquid core and the solid crust of a neutron star. A theoretical framework that includes the thermodynamic method, relativistic nuclear energy density functionals, and the quasiparticle random-phase approximation is employed in a self-consistent calculation of (nt,Pt) and collective excitations in nuclei. Covariance analysis shows that properties of charge-exchange dipole transitions, isovector giant dipole and quadrupole resonances, and pygmy dipole transitions are correlated with the core-crust transition density and pressure. A set of relativistic nuclear energy density functionals, characterized by systematic variation of the density dependence of the symmetry energy of nuclear matter, is used to constrain possible values for (nt,Pt). By comparing the calculated excitation energies of giant resonances, energy-weighted pygmy dipole strength, and dipole polarizability with available data, we obtain the weighted average values: nt=0.0955±0.0007 fm-3 and Pt=0.59±0.05 MeV fm-3. This approach crucially depends on experimental results for collective excitations in nuclei and, therefore, accurate measurements are necessary to further constrain the structure of the crust of neutron stars.

  9. Excited-to-excited-state scattering using weak measurements

    NASA Astrophysics Data System (ADS)

    U, Satya Sainadh; Narayanan, Andal

    2015-11-01

    Weak measurements are a subset of measurement processes in quantum mechanics wherein the system, which is being measured, interacts very weakly with the measuring apparatus. Measurement values of observables undergoing a weak interaction and their amplification are concepts that have sharpened our understanding of interaction processes in quantum mechanics. Recent experiments show that naturally occurring processes such as resonance fluorescence from excited states of an atom can exhibit weak value amplification effect. In this paper we theoretically analyze the process of elastic resonance fluorescence from a V -type three-level atomic system, using the well-known Weiskopff-Wigner (WW) theory of spontaneous emission. Within this theory we show that a weak interaction regime can be identified and for suitable choices of initial and final excited states the mean scattering time between these states show an amplification effect during interaction with the vacuum bath modes of the electromagnetic field. We thus show that a system-bath interaction can show weak value amplification. Using our theory we reproduce the published experimental results carried out in such a system. More importantly, our theory can calculate scattering time scales in elastic resonance scattering between multiple excited states of a single atom or between common excited state configurations of interacting multiatom systems.

  10. Excited to excited state scattering using weak measurements

    E-print Network

    Satya Sainadh U; Andal Narayanan

    2015-11-06

    Weak measurements are a subset of measurement processes in quantum mechanics wherein the system which is being measured interacts very weakly with the measuring apparatus. Measurement values of observables undergoing a weak interaction and their amplification, are concepts that have sharpened our understanding of interaction processes in quantum mechanics. Recent experiments show that naturally occurring processes such as resonance fluorescence from excited states of an atom can exhibit weak value amplification effect. In this paper, we theoretically analyze the process of elastic resonance fluorescence from a V-type three level atomic system, using the well known Weiskopff-Wigner (W-W) theory of spontaneous emission. Within this theory, we show that, a weak interaction regime can be identified and for suitable choices of initial and final excited states, the mean scattering time between these states show an amplification effect during interaction with the vacuum bath modes of the electromagnetic field. We thus show for the first time that a system bath interaction can show weak value amplification. Using our theory we reproduce the published experimental results carried out in such a system. More importantly, our theory can calculate scattering timescales in elastic resonance scattering between multiple excited states of a single atom or between common excited state configurations of interacting multi-atom systems.

  11. Band Excitation in Scanning Probe Microscopy: Sines of Change

    SciTech Connect

    Jesse, Stephen; Kalinin, Sergei V

    2011-01-01

    In three decades since Scanning Probe Microscopy (SPM) methods have entered scientific arena, they have become one of the main tool of nanoscale science and technology by offering the capability for imaging topography, magnetic, electrical, and mechanical properties on the nanometer scale. The vast majority of force-based SPM techniques to date are based on single-frequency sinusoidal excitation and detection. Here, we illustrate the intrinsic limitations of single-frequency detection that stem from the fundamental physics of dynamic systems. Consequently, many aspects of nanoscale materials functionality including quantitative mechanical, magnetic, and electrical measurements, probing dissipative interactions, to name a few remain unexplored. Band excitation is illustrated as a universal alternative to traditional single-frequency techniques that allows quantitative and reliable studies of dissipative and conservative phenomena, and can be universally applied to all ambient and liquid SPM methods.

  12. Aspects of data on the breakup of highly excited nuclei

    SciTech Connect

    Warwick, A.I.; Wieman, H.H.; Gutbrod, H.H.; Ritter, H.G.; Stelzer, H.; Weik, F.; Kaufman, S.B.; Steinberg, E.P.; Wilkins, B.D.

    1983-05-01

    There is an awakening of theoretical interest in the mechanisms by which nuclear fragments (4 less than or equal to A less than or equal to 150) are produced in violent collisions of heavy ions. With this in mind we review some aspects of the available experimental data and point out some challenging features against which to test the models. The concept of evaporation is tremendously powerful when applied to pieces of nuclei of low excitation (1 or 2 MeV/u). Current interest focuses on higher excitations, at the point where the binding energy of the system vanishes. This is the transition from liquid nuclei to a gas of nucleons, and it may be that the critical phenomena that certainly exist in infinite nuclear matter will be manifest in finite nuclei under these conditions.

  13. Magnetically induced pulser laser excitation

    SciTech Connect

    Taylor, R.S.; Leopold, K.E.

    1985-02-15

    A novel excitation scheme has been developed for excimer discharge lasers. The technique uses pulse transformer technology to induce a fast, high voltage pulse directly onto a ground potential laser electrode resulting in the breakdown of the laser gas mix. Saturation of the pulse transformer core inductance then permits efficient energy transfer from the main energy storage circuit into the discharge. When this excitation technique was used in a XeCl laser an output energy density of 2.5 J/l and an overall electrical to optical efficiency of 2% were obtained. The technique appears promising for the development of high energy, high average power excimer lasers.

  14. Excited Fermions at H1

    E-print Network

    E. Sauvan; for the H1 Collaboration

    2007-09-05

    We present a search for excited neutrinos and electrons using all data collected by the H1 experiment at HERA at a center-of-mass energy of 320 GeV with an integrated luminosity of up to 435 pb$^{-1}$. No evidence for excited neutrino or electron production is found. Mass dependent exclusion limits are determined for the ratio of the coupling to the compositeness scale, $f/{\\Lambda}$. These limits greatly extend the excluded region to higher masses than has been possible in previous searches.

  15. Faraday Discuss., 1997, 108, 115130 Excited state dynamics in clusters of oxygen

    E-print Network

    Continetti, Robert E.

    clusters of oxygen. Oxygen clusters and liquid oxygen have a com- plicated chemistry due to numerous lowFaraday Discuss., 1997, 108, 115È130 Excited state dynamics in clusters of oxygen Runjun Li, Karl A) dynamics of small anionic clusters of oxygen. We Ðnd that the dynamics of the neutral DPD pathway

  16. LIFETIME OF THE EXCITED STATE IN VIVO I. CHLOROPHYLL a IN ALGAE, AT ROOM

    E-print Network

    Govindjee

    LIFETIME OF THE EXCITED STATE IN VIVO I. CHLOROPHYLL a IN ALGAE, AT ROOM AND AT LIQUID NITROGEN decay of chloro- phyll (Chl) a in the green alga Chlorella pyrenoidosa, the red alga Porphyridium cruentum, and the blue-green alga Anacystis nidulans was measured by the phase- shift method under

  17. Comparison of laser excited fluorescence and photoacoustic limits of detection for static and flow cells

    SciTech Connect

    Voigtman, E.; Jurgensen, A.; Winefordner, J.D.

    1981-10-01

    The fluorescence and photoacoustic characteristics of a windowless flow cell intended for liquid chromatographic applications are compared with respective characteristics of a static cuvette cell. In addition, a photoionization mode of operation for the flow cell is exhibited which utilizes the ionization products of two-photon excitation of polynuclear aromatic hydrocarbons in n-alkanes to effect a sensitive detection of those PAHs.

  18. Cosmology with liquid mirror telescopes

    NASA Technical Reports Server (NTRS)

    Hogg, David W.; Gibson, Brad K.; Hickson, Paul

    1993-01-01

    Liquid mirrors provide an exciting means to obtain large optical telescopes for substantially lower costs than conventional technologies. The liquid mirror concept has been demonstrated in the lab with the construction of a diffraction limited 1.5 m mirror. The mirror surface, using liquid mercury, forms a perfect parabolic shape when the mirror cell is rotated at a uniform velocity. A liquid mirror must be able to support a heavy mercury load with minimal flexure and have a fundamental resonant frequency that is as high as possible, to suppress the amplitude of surface waves caused by small vibrations transmitted to the mirror. To minimize the transmission of vibrations to the liquid surface, the entire mirror rests on an air bearing. This necessitates the mirror cell being lightweight, due to the limited load capabilities of the air bearing. The mirror components must also have physical characteristics which minimize the effects of thermal expansion with ambient temperature fluctuations in the observatory. In addition, the 2.7 m mirror construction is designed so that the techniques used may be readily extended to the construction of large mirrors. To attain the goals of a lightweight, rigid mirror, a composite laminant construction was used. The mirror consists of a foam core cut to the desired parabolic shape, with an accuracy of a few mm. An aluminum hub serves as an anchor for the foam and skin, and allows precise centering of the mirror on the air bearing and drive system. Several plys of Kevlar, covered in an epoxy matrix, are then applied to the foam. A final layer of pure epoxy is formed by spin casting. This final layer is parabolic to within a fraction of a mm. An aluminum ring bonded to the circumference of the mirror retains the mercury, and incorporates stainless-steel hard-points for the attachment of balance weights.

  19. Liquid foams of graphene

    E-print Network

    Alcazar Jorba, Daniel

    2012-01-01

    Liquid foams are dispersions of bubbles in a liquid. Bubbles are stabilized by foaming agents that position at the interface between the gas and the liquid. Most foaming agents, such as the commonly used sodium dodecylsulfate, ...

  20. Lacerations - liquid bandage

    MedlinePLUS

    Skin adhesives; Tissue adhesive ... the cut is minor, a liquid bandage (liquid adhesive) can be used on the cut to close ... bandage is quick and painless to apply. Skin adhesives, or liquid bandages, seal the cut closed after ...

  1. Liquid Crystal Devices.

    ERIC Educational Resources Information Center

    Bradshaw, Madeline J.

    1983-01-01

    The nature of liquid crystals and several important liquid crystal devices are described. Ideas for practical experiments to illustrate the properties of liquid crystals and their operation in devices are also described. (Author/JN)

  2. Liquid Crystal Inquiries.

    ERIC Educational Resources Information Center

    Marroum, Renata-Maria

    1996-01-01

    Discusses the properties and classification of liquid crystals. Presents a simple experiment that illustrates the structure of liquid crystals and the differences between the various phases liquid crystals can assume. (JRH)

  3. Transport currents in Bose quantum liquids

    SciTech Connect

    Apaja, V.; Krotscheck, E.; Rimnac, A.; Zillich, R. E.

    2006-09-07

    Until now, most of what has been said about excitations in quantum liquids has concerned the dynamic structure function, which is observable by means of neutron scattering. The dynamic structure function can be calculated using standard linear response theory. However, at this level one needs only transition densities <0{rho}n> or transition currents <0jn>, which are oscillatory in time and hence do not describe mass transport. In this work we go a step further and study transport currents in excited states, , which requires the calculation of to second order. For that purpose, we take a well-tested microscopic theory of inhomogeneous quantum liquids and extend it to find the currents formed when helium atoms scatter off a helium slab or when excitations evaporate atoms (a setup experimented by A. F. G. Wyatt's group in Exeter). Current conservation was already a major theoretical problem encountered by R. Feynman and led him to introduce backflow corrections. We show that perfect current conservation is expected only for exact solutions of the time-dependent many-body Schroedinger equation. This is the first extensive theoretical study of transport phenomena in a quantum liquid based on an accurate microscopic theory.

  4. Renormalization group analysis of thermal transport in the disordered Fermi liquid

    NASA Astrophysics Data System (ADS)

    Schwiete, G.; Finkel'stein, A. M.

    2014-10-01

    We present a detailed study of thermal transport in the disordered Fermi liquid with short-range interactions. At temperatures smaller than the impurity scattering rate, i.e., in the diffusive regime, thermal conductivity acquires nonanalytic quantum corrections. When these quantum corrections become large at low temperatures, the calculation of thermal conductivity demands a theoretical approach that treats disorder and interactions on an equal footing. In this paper, we develop such an approach by merging Luttinger's idea of using gravitational potentials for the analysis of thermal phenomena with a renormalization group calculation based on the Keldysh nonlinear sigma model. The gravitational potentials are introduced in the action as auxiliary sources that couple to the heat density. These sources are a convenient tool for generating expressions for the heat density and its correlation function from the partition function. Already in the absence of the gravitational potentials, the nonlinear sigma model contains several temperature-dependent renormalization group charges. When the gravitational potentials are introduced into the model, they acquire an independent renormalization group flow. We show that this flow preserves the phenomenological form of the correlation function, reflecting its relation to the specific heat and the constraints imposed by energy conservation. The main result of our analysis is that the Wiedemann-Franz law holds down to the lowest temperatures even in the presence of disorder and interactions and despite the quantum corrections that arise for both the electric and thermal conductivities.

  5. Resonance cavitation oscillations of a liquid in pipelines

    NASA Astrophysics Data System (ADS)

    Galiev, Sh. U.; Iakovtsov, A. V.

    The formation of periodic discontinuous oscillations of a gas and a liquid in pipelines is investigated in the context of continuum mechanics. A finite difference method oriented at the solution of such problems is selected using the criteria of accuracy and efficiency. A comparison is made between numerical and experimental results obtained for pressure oscillations excited in a gas and a liquid moved harmonically by a piston at resonance frequencies.

  6. Contact resonance atomic force microscopy imaging in air and water using photothermal excitation

    NASA Astrophysics Data System (ADS)

    Kocun, Marta; Labuda, Aleksander; Gannepalli, Anil; Proksch, Roger

    2015-08-01

    Contact Resonance Force Microscopy (CR-FM) is a leading atomic force microscopy technique for measuring viscoelastic nano-mechanical properties. Conventional piezo-excited CR-FM measurements have been limited to imaging in air, since the "forest of peaks" frequency response associated with acoustic excitation methods effectively masks the true cantilever resonance. Using photothermal excitation results in clean contact, resonance spectra that closely match the ideal frequency response of the cantilever, allowing unambiguous and simple resonance frequency and quality factor measurements in air and liquids alike. This extends the capabilities of CR-FM to biologically relevant and other soft samples in liquid environments. We demonstrate CR-FM in air and water on both stiff silicon/titanium samples and softer polystyrene-polyethylene-polypropylene polymer samples with the quantitative moduli having very good agreement between expected and measured values.

  7. Pattern Formation in Excitable Media

    NASA Astrophysics Data System (ADS)

    Mikhailov, Alexander S.

    1997-03-01

    In this talk I give a short review of the history and the current state of theoretical research on spiral wave patterns in excitable media. I start with the theoretical model of wave propagation in excitable media proposed in 1946 by Wiener and Rosenblueth(N. Wiener and A. Rosenblueth, The mathematical formulation of the problem of conduction of impulses in a network of connected excitable elements, specifically in cardiac muscle, Arch. Inst. Cardiol. Mexico 16 (1946) 205). This model describes spiral waves rotating around obstacles. I show how, by taking additionally into account curvature effects and gradual recovery of the medium after passage of an excitation wave, the model is generalized to describe freely rotating spiral waves and the breakup which produces spirals. In the context of this kinematic model, complex dynamics of spiral waves, i.e. their meandering, drift and resonance, is discussed. Instabilities of spiral waves in confined geometries, i.e. inside a circular region and on a sphere, are analyzed. At the end, I show how spiral waves in such systems can be efficiently controlled by application of a delayed global feedback. The talk is based on the review paper(A. S. Mikhailov, V. A. Davydov, and V. S. Zykov, Complex dynamics of spiral waves and motion of curves, Physica D 70 (1994) 1) and the monograph(A. S. Mikhailov, Foundations of Synergetics I, 2nd revised edition (Springer, Berlin, 1994)).

  8. High Excitation Gas and ISM

    NASA Technical Reports Server (NTRS)

    Peeters, E.; Martin-Hernandez, N. L.; Rodriguez-Fernandez, N. J.; Tielens, A. G. G. M.

    2004-01-01

    An overview is given of ISO results on regions of high excitation ISM and gas, i.e. HII regions, the Galactic Centre and Supernovae Remnants. IR emission due to fine-structure lines, molecular hydrogen, silicates, polycyclic aromatic hydrocarbons and dust are summarized, their diagnostic capabilities illustrated and their implications highlighted.

  9. Communicating the Excitement of Science

    ScienceCinema

    Michael Turner

    2010-01-08

    In this talk (which will include some exciting science) I will discuss some lessons I have learned about communicating science to scientists (in my own field and others), students, the public, the press, and policy makers in giving 500+ colloquia and seminars, 300+ public lectures and many informal presentations (including cocktail parties).

  10. Launch Excitement with Water Rockets

    ERIC Educational Resources Information Center

    Sanchez, Juan Carlos; Penick, John

    2007-01-01

    Explosions and fires--these are what many students are waiting for in science classes. And when they do occur, students pay attention. While we can't entertain our students with continual mayhem, we can catch their attention and cater to their desires for excitement by saying, "Let's make rockets." In this activity, students make simple, reusable…

  11. Communicating the Excitement of Science

    SciTech Connect

    Michael Turner

    2009-06-05

    In this talk (which will include some exciting science) I will discuss some lessons I have learned about communicating science to scientists (in my own field and others), students, the public, the press, and policy makers in giving 500+ colloquia and seminars, 300+ public lectures and many informal presentations (including cocktail parties).

  12. An incompressible state of a photo-excited electron gas

    PubMed Central

    Chepelianskii, Alexei D.; Watanabe, Masamitsu; Nasyedkin, Kostyantyn; Kono, Kimitoshi; Konstantinov, Denis

    2015-01-01

    Two-dimensional electrons in a magnetic field can form new states of matter characterized by topological properties and strong electronic correlations as displayed in the integer and fractional quantum Hall states. In these states, the electron liquid displays several spectacular characteristics, which manifest themselves in transport experiments with the quantization of the Hall resistance and a vanishing longitudinal conductivity or in thermodynamic equilibrium when the electron fluid becomes incompressible. Several experiments have reported that dissipationless transport can be achieved even at weak, non-quantizing magnetic fields when the electrons absorb photons at specific energies related to their cyclotron frequency. Here we perform compressibility measurements on electrons on liquid helium demonstrating the formation of an incompressible electronic state under these resonant excitation conditions. This new state provides a striking example of irradiation-induced self-organization in a quantum system. PMID:26007282

  13. An incompressible state of a photo-excited electron gas.

    PubMed

    Chepelianskii, Alexei D; Watanabe, Masamitsu; Nasyedkin, Kostyantyn; Kono, Kimitoshi; Konstantinov, Denis

    2015-01-01

    Two-dimensional electrons in a magnetic field can form new states of matter characterized by topological properties and strong electronic correlations as displayed in the integer and fractional quantum Hall states. In these states, the electron liquid displays several spectacular characteristics, which manifest themselves in transport experiments with the quantization of the Hall resistance and a vanishing longitudinal conductivity or in thermodynamic equilibrium when the electron fluid becomes incompressible. Several experiments have reported that dissipationless transport can be achieved even at weak, non-quantizing magnetic fields when the electrons absorb photons at specific energies related to their cyclotron frequency. Here we perform compressibility measurements on electrons on liquid helium demonstrating the formation of an incompressible electronic state under these resonant excitation conditions. This new state provides a striking example of irradiation-induced self-organization in a quantum system. PMID:26007282

  14. Excitation of slosh waves associated with low frequency impulsive reverse gravity acceleration of geyser initiation

    NASA Technical Reports Server (NTRS)

    Hung, R. J.; Shyu, K. L.

    1992-01-01

    The objective of the cryogenic fluid management of the spacecraft propulsion system is to develop the technology necessary for acquisition or positioning of liquid and vapor within a tank in reduced gravity to enable liquid outflow or vapor venting. The requirement to settle or to position liquid fuel over the outlet end of the spacecraft propellant tank prior to main engine restart poses a microgravity fluid behavior problem. The purpose of the present study is to investigate the stability of the most efficient technique for propellant resettling through the minimization of propellant usage and weight penalties. In this study slosh wave excitation induced by the resettling flow field activated by 0.1 Hz low frequency, impulsive reverse gravity acceleration, during reorientation with the initiation of geyser for liquid fill levels of 30, 50, 65, 70 and 80 percent, have been studied. Characteristics of slosh waves with various frequencies excited are discussed. Slosh wave excitation shift the fluid mass distribution in the container which impose time dependent variations in spacecraft moment of inertia. This information is important for the spacecraft control during the course of liquid reorientation.

  15. The electromechanics of liquids electrowetting (EWOD) & liquid

    E-print Network

    Jones, Thomas B.

    experiment with cryogenic liquids Lumped parameter electromechanical model successfully predicts height-of-rise at the midpoint ... but NOT the details of meniscus profile. hcap hDEP V D cryogenic liquid: l, l g vapor phase cryogenic liquid: l, l w h = hcap+hDEP view thru electrodes profile does not depend on E #12;12 Pellat

  16. Band excitation Kelvin probe force microscopy utilizing photothermal excitation

    SciTech Connect

    Collins, Liam E-mail: liq1@ORNL.gov; Rodriguez, Brian J.; Jesse, Stephen; Balke, Nina; Kalinin, Sergei; Li, Qian E-mail: liq1@ORNL.gov

    2015-03-09

    A multifrequency open loop Kelvin probe force microscopy (KPFM) approach utilizing photothermal as opposed to electrical excitation is developed. Photothermal band excitation (PthBE)-KPFM is implemented here in a grid mode on a model test sample comprising a metal-insulator junction with local charge-patterned regions. Unlike the previously described open loop BE-KPFM, which relies on capacitive actuation of the cantilever, photothermal actuation is shown to be highly sensitive to the electrostatic force gradient even at biases close to the contact potential difference (CPD). PthBE-KPFM is further shown to provide a more localized measurement of true CPD in comparison to the gold standard ambient KPFM approach, amplitude modulated KPFM. Finally, PthBE-KPFM data contain information relating to local dielectric properties and electronic dissipation between tip and sample unattainable using conventional single frequency KPFM approaches.

  17. Diffusion and excitation transfer of excited alkali-metal atoms

    NASA Astrophysics Data System (ADS)

    Bouledroua, M.; Dalgarno, A.; Côté, R.

    2002-01-01

    We report calculations of diffusion, excitation transfer, width, and shift cross sections. We use these cross sections to obtain the diffusion coefficient and the width and line shift due to collisions of alkali-metal atoms in the impact approximation. The results are compared to analytical expressions obtained from semiclassical treatments, and with measured widths for sodium atoms. Extension to other alkali metal atoms is also given.

  18. Twist liquids and gauging anyonic symmetries

    NASA Astrophysics Data System (ADS)

    Teo, Jeffrey; Hughes, Taylor; Fradkin, Eduardo

    2015-03-01

    Topological phases of matter in (2 + 1) D are frequently equipped with global symmetries that relabel anyons without changing the fusion and braiding structures. Twist defects are static symmetry fluxes that permute the labels of orbiting anyons. Gauging or melting these symmetries by quantizing defects into dynamical excitations leads to a wide class of more exotic topological phases known as twist liquids. We formulate a general gauging framework, characterize the anyon structure of twist liquids and provide solvable lattice models that capture the gauging phase transitions. Generalizing a discrete gauge theory, we represent the anyons in a twist liquid by compositions of not only fluxes and charges but also quasiparticle supersectors. We show the gauging transition amplifies the total quantum dimension by | G | , the order of the symmetry group, and thus modifies the topological entanglement entropy.

  19. Electrokinetics over liquid/liquid interfaces

    NASA Astrophysics Data System (ADS)

    Squires, Todd M.

    2011-11-01

    Since liquid-liquid interfaces flow in response to an applied stress, one might expect electrokinetic flows at liquid-liquid interfaces to be significantly higher than over liquid-solid interfaces. The earliest predictions for the electrophoretic mobility of charged mercury drops - distinct approaches by Frumkin and Levich (1946), and Booth (1951) - differed by O (a /?D) , where a is the radius of the drop and ?D is the Debye screening length. Seeking to reconcile this rather striking discrepancy, Levine (1973) showed double-layer polarization to be the key ingredient. Without a physical mechanism by which electrokinetic effects are enhanced, however, it is difficult to know how general the enhancement is - whether it holds only for liquid metal surfaces, or more generally, for all liquid/liquid surfaces. By considering a series of systems in which a planar metal strip is coated with either a liquid metal or liquid dielectric, we show that the central physical mechanism behind the enhancement predicted by Frumkin and Levich (1946) is the presence of an unmatched electrical stress upon the electrolyte-liquid interface, which establishes a Marangoni stress on the droplet surface and drives it into motion. The source of the unbalanced electrokinetic stress on a liquid metal surface is clear - metals represent equipotential surfaces, so no field exists to drive an equal and opposite force on the surface charge. This might suggest that liquid metals represent a unique system, since dielectric liquids can support finite electric fields, which might be expected to exert an electrical stress on the surface charge that balances the electric stress. We demonstrate, however, that electrical and osmotic stresses on relaxed double-layers internal to dielectric liquids precisely cancel, so that internal electrokinetic stresses generally vanish in closed, ideally polarizable liquids. The enhancement for liquid mercury drops can thus be expected quite generally over clean, ideally polarizable liquid drops. More broadly, the ability to reliably engineer liquid interfaces in microfluidic systems, then, may provide a path to significantly enhanced electrokinetic flows. Research done in collaboration with A. J. Pascall.

  20. Ionic Liquids Database- (ILThermo)

    National Institute of Standards and Technology Data Gateway

    SRD 147 Ionic Liquids Database- (ILThermo) (Web, free access)   IUPAC Ionic Liquids Database, ILThermo, is a free web research tool that allows users worldwide to access an up-to-date data collection from the publications on experimental investigations of thermodynamic, and transport properties of ionic liquids as well as binary and ternary mixtures containing ionic liquids.

  1. Autoresonant excitation of dark solitons.

    PubMed

    Borich, M A; Shagalov, A G; Friedland, L

    2015-01-01

    Continuouslyphase-locked (autoresonant) dark solitons of the defocusing nonlinear Schrodinger equation are excited and controlled by driving the system by a slowly chirped wavelike perturbation. The theory of these excitations is developed using Whitham's averaged variational principle and compared with numerical simulations. The problem of the threshold for transition to autoresonance in the driven system is studied in detail, focusing on the regime when the weakly nonlinear frequency shift in the problem differs from the typical quadratic dependence on the wave amplitude. The numerical simulations in this regime show a deviation of the autoresonance threshold on the driving amplitude from the usual 3/4 power dependence on the driving frequency chirp rate. The theory of this effect is suggested. PMID:25679688

  2. Spatiotemporal control of nanooptical excitations

    PubMed Central

    Aeschlimann, Martin; Bauer, Michael; Bayer, Daniela; Brixner, Tobias; Cunovic, Stefan; Dimler, Frank; Fischer, Alexander; Pfeiffer, Walter; Rohmer, Martin; Schneider, Christian; Steeb, Felix; Strüber, Christian; Voronine, Dmitri V.

    2010-01-01

    The most general investigation and exploitation of light-induced processes require simultaneous control over spatial and temporal properties of the electromagnetic field on a femtosecond time and nanometer length scale. Based on the combination of polarization pulse shaping and time-resolved two-photon photoemission electron microscopy, we demonstrate such control over nanoscale spatial and ultrafast temporal degrees of freedom of an electromagnetic excitation in the vicinity of a nanostructure. The time-resolved cross-correlation measurement of the local photoemission yield reveals the switching of the nanolocalized optical near-field distribution with a lateral resolution well below the diffraction limit and a temporal resolution on the femtosecond time scale. In addition, successful adaptive spatiotemporal control demonstrates the flexibility of the method. This flexible simultaneous control of temporal and spatial properties of nanophotonic excitations opens new possibilities to tailor and optimize the light–matter interaction in spectroscopic methods as well as in nanophotonic applications. PMID:20212153

  3. Tachyonic thermal excitations and causality

    E-print Network

    Ernst Trojan; George V. Vlasov

    2011-10-08

    We consider an ideal Fermi gas of tachyonic thermal excitations as a continuous medium and establish when it satisfies the causality condition. At high temperature the sound speed is always subluminal $c_stachyon matter below the critical temperature $T_ctachyon mass $m$. The pressure $P$ and energy density $E$ cannot be arbitrary small, but $P$ can exceed $E$, and $P=2.36E$ when $T\\rightarrow T_c$.

  4. Oscillator response to nonstationary excitation

    NASA Technical Reports Server (NTRS)

    Spanos, P.-T. D.; Solomos, G. P.

    1984-01-01

    Analytical solutions are presented regarding probability density distributions of various response parameters of a lightly damped oscillator. The oscillator is subjected to a broad-band stochastic excitation which possesses a time-variant power spectrum. The analytical solutions are derived by utilizing appropriate Fokker-Planck equations which govern Markovian approximations of the response parameters considered. The reliability of the approximate analytical solution is tested by using pertinent data generated by a digital Monte Carlo study.

  5. Liquid crystal polyester thermosets

    SciTech Connect

    Benicewicz, B.C.; Hoyt, A.E.

    1990-01-01

    The present invention relates to the field of curable liquid crystal polyester monomers and to thermoset liquid crystalline polyester compositions prepared therefrom. It is an object of this invention to provide curable liquid crystalline polyester materials. Another object of this invention is to provide a process of preparing curable liquid crystal polyester monomers. Yet another object of this invention is to provide liquid crystalline blends of polyester materials. It is a further object of this invention to provide thermoset liquid crystalline polyester compositions. It is a still further object of this invention to provide thermoset liquid crystalline polyester compositions having a high heat resistance. 1 fig.

  6. Liquid crystal polyester thermosets

    SciTech Connect

    Benicewicz, B.C.; Hoyt, A.E.

    1990-12-31

    The present invention relates to the field of curable liquid crystal polyester monomers and to thermoset liquid crystalline polyester compositions prepared therefrom. It is an object of this invention to provide curable liquid crystalline polyester materials. Another object of this invention is to provide a process of preparing curable liquid crystal polyester monomers. Yet another object of this invention is to provide liquid crystalline blends of polyester materials. It is a further object of this invention to provide thermoset liquid crystalline polyester compositions. It is a still further object of this invention to provide thermoset liquid crystalline polyester compositions having a high heat resistance. 1 fig.

  7. Wedding ring shaped excitation coil

    DOEpatents

    MacLennan, Donald A. (Gaithersburg, MD); Tsai, Peter (Olney, MD)

    2001-01-01

    A high frequency inductively coupled electrodeless lamp includes an excitation coil with an effective electrical length which is less than one half wavelength of a driving frequency applied thereto, preferably much less. The driving frequency may be greater than 100 MHz and is preferably as high as 915 MHz. Preferably, the excitation coil is configured as a non-helical, semi-cylindrical conductive surface having less than one turn, in the general shape of a wedding ring. At high frequencies, the current in the coil forms two loops which are spaced apart and parallel to each other. Configured appropriately, the coil approximates a Helmholtz configuration. The lamp preferably utilizes an bulb encased in a reflective ceramic cup with a pre-formed aperture defined therethrough. The ceramic cup may include structural features to aid in alignment and/or a flanged face to aid in thermal management. The lamp head is preferably an integrated lamp head comprising a metal matrix composite surrounding an insulating ceramic with the excitation integrally formed on the ceramic. A novel solid-state oscillator preferably provides RF power to the lamp. The oscillator is a single active element device capable of providing over 70 watts of power at over 70% efficiency.

  8. Vibrationally excited hydroxyl tagging velocimetry.

    PubMed

    Grady, Nathan; Pitz, Robert W

    2014-11-01

    A new molecular-based velocity method is developed for high-temperature flame gases based on the hydroxyl tagging velocimetry (HTV) technique. In vibrationally excited HTV (VE-HTV), two photons from a KrF laser (248 nm) dissociate H2O into a tag line of vibrationally excited OH (v=1). The excited state OH tag is selectively detected in a background of naturally occurring ground state OH (v=0). In atmospheric pressure laboratory burners, the OH (v=1) tag persists for 5-10 ?s, allowing single-shot velocity measurements along a 2 cm line under lean, stoichiometric, and rich flame conditions with temperatures reaching 2300 K. Mean velocity measurements are demonstrated in a lean (?=0.78) premixed H2/air turbulent flame (Re=26,550) laboratory flame. The VE-HTV method is best suited to measure high-speed velocities in hot combustion environments in the presence of background OH. PMID:25402874

  9. ACTIVE INSTABILITY CONTROL EFFECTIVENESS IN A LIQUID FUELED COMBUSTOR

    E-print Network

    Lieuwen, Timothy C.

    ACTIVE INSTABILITY CONTROL EFFECTIVENESS IN A LIQUID FUELED COMBUSTOR ADAM COKER YEDIDIA NEUMEIER, Atlanta, Georgia, USA This note describes active instability control experiments in a high pressure, Jet A-fueled at two conditions where the linear and nonlinear characteristics of the self-excited oscillations were

  10. Energy-Trapping Torsional-Mode Resonators for Liquid Sensing

    E-print Network

    Huang, Rui

    . By coupling thickness-shear vibrations of a finite crystal plates and wave propagations in a Newtonian liquid plate, torsional-mode vibrations do not coupled with flexural mode, thus no out-of-plane motion have demonstrated that energy-trapping torsional-mode vibrations can be excited in elastic plates

  11. Resource Paper: Molecular Excited State Relaxation Processes.

    ERIC Educational Resources Information Center

    Rhodes, William

    1979-01-01

    Develops the concept of oscillatory v dissipative limits as it applies to electronic excited state processes in molecular systems. Main emphasis is placed on the radiative and nonradiative dynamics of the excited state of a molecule prepared by interaction with light or some other excitation source. (BT)

  12. Tuning the Pitch of a Wine Glass by Playing with the Liquid inside

    ERIC Educational Resources Information Center

    Courtois, Matthieu; Guirao, Boris; Fort, Emmanuel

    2008-01-01

    It is well known that the pitch of the sound produced by an excited glass shell can be tuned by adding some liquid in it. In this paper, it will be proved that the distribution of the liquid inside the shell plays a crucial role in this frequency shift. Thus it provides another way to tune the pitch of the sound by modifying the liquid

  13. Laser cooling and control of excitations in superfluid helium

    E-print Network

    G. I. Harris; D. L. McAuslan; E. Sheridan; Y. Sachkou; C. Baker; W. P. Bowen

    2015-06-15

    Superfluidity is an emergent quantum phenomenon which arises due to strong interactions between elementary excitations in liquid helium. These excitations have been probed with great success using techniques such as neutron and light scattering. However measurements to-date have been limited, quite generally, to average properties of bulk superfluid or the driven response far out of thermal equilibrium. Here, we use cavity optomechanics to probe the thermodynamics of superfluid excitations in real-time. Furthermore, strong light-matter interactions allow both laser cooling and amplification of the thermal motion. This provides a new tool to understand and control the microscopic behaviour of superfluids, including phonon-phonon interactions, quantised vortices and two-dimensional quantum phenomena such as the Berezinskii-Kosterlitz-Thouless transition. The third sound modes studied here also offer a pathway towards quantum optomechanics with thin superfluid films, including femtogram effective masses, high mechanical quality factors, strong phonon-phonon and phonon-vortex interactions, and self-assembly into complex geometries with sub-nanometre feature size.

  14. Theoretical model of liquid metals

    SciTech Connect

    Kerley, G.I.

    1981-01-01

    A theory for calculating the bulk properties of metals and other materials is described. The approach is based upon the fluid perturbation theory of Kerley and the electronic structure model of Liberman. Application of the theory involves three steps. First, the zero Kelvin isotherm of the solid is constructed from electronic structure calculations, experimental data, or both. This curve contains information about the effective interactions between atoms in the ground electronic state. Next, the cold curve is combined with perturbation theory to compute contributions from thermal motion of the atoms to the liquid properties. Finally, contributions from thermal electron excitation are computed using the electronic structure model. This paper shows that theory agrees well with experimental data for xenon and iron.

  15. Speech synthesis by glottal excited linear prediction.

    PubMed

    Childers, D G; Hu, H T

    1994-10-01

    This paper describes a linear predictive (LP) speech synthesis procedure that resynthesizes speech using a 6th-order polynomial waveform to model the glottal excitation. The coefficients of the polynomial model form a vector that represents the glottal excitation waveform for one pitch period. A glottal excitation code book with 32 entries for voiced excitation is designed and trained using two sentences spoken by different speakers. The purpose for using this approach is to demonstrate that quantization of the glottal excitation waveform does not significantly degrade the quality of speech synthesized with a glottal excitation linear predictive (GELP) synthesizer. This implementation of the LP synthesizer is patterned after both a pitch-excited LP speech synthesizer and a code excited linear predictive (CELP) speech coder. In addition to the glottal excitation codebook, we use a stochastic codebook with 256 entries for unvoiced noise excitation. Analysis techniques are described for constructing both codebooks. The GELP synthesizer, which resynthesizes speech with high quality, provides the speech scientist a simple speech synthesis procedure that uses established analysis techniques, that is able to reproduce all speed sounds, and yet also has an excitation model waveform that is related to the derivative of the glottal flow and the integral of the residue. It is conjectured that the glottal excitation codebook approach could provide a mechanism for quantitatively comparing the differences in glottal excitation codebooks for male and female speakers and for speakers with vocal disorders and for speakers with different voice types such as breathy and vocal fry voices. Conceivably, one could also convert the voice of a speaker with one voice type, e.g., breathy, to the voice of a speaker with another voice type, e.g., vocal fry, by synthesizing speech using the vocal tract LP parameters for the speaker with the breathy voice excited by the glottal excitation codebook trained for vocal fry. PMID:7963019

  16. Peculiarities of collisional excitation transfer with excited screened energy levels of atoms

    SciTech Connect

    Gerasimov, V. A.; Gerasimov, V. V.; Pavlinskiy, A. V.

    2007-09-15

    We report an experimental discovery of deviations from the known regularities in collisional excitation transfer processes for metal atoms. The collisional excitation transfer with excited screened energy levels of thulium and dysprosium atoms is studied. The selecting role of the screening 6s shell in collisional excitation transfer is shown.

  17. Bose-Metals and non-Fermi-liquid metals Underlying the quantum theory of many-particle non-relativistic systems

    E-print Network

    Bose-Metals and non-Fermi-liquid metals Underlying the quantum theory of many-particle non-relativistic systems are the canonical quantum fluids - superfluid phases of Bosons and Fermi- liquid phases mode of the broken particle number conservation, while the dom- inant excitations in a Fermi-liquid

  18. Second-Harmonic-Generation Microscopy Using Excitation Beam with Controlled Polarization Pattern to Determine Three-Dimensional Molecular Orientation

    NASA Astrophysics Data System (ADS)

    Yoshiki, Keisuke; Hashimoto, Mamoru; Araki, Tsutomu

    2005-08-01

    We have developed a second-harmonic-generation (SHG) microscope using an excitation beam with a controlled polarization pattern in order to detect three-dimensional molecular orientation. The electric field at the focus is controlled three-dimensionally by modifying the polarization distribution with a parallel-aligned nematic-liquid-crystal spatial-light-modulator without any mechanical moving parts. We demonstrated that the SHG signal from an Achilles tendon, sliced so that collagen fibers were aligned parallel to the optical axis, excited by a radially polarized beam was higher than those excited by linearly polarized beams. The possibility of determinating three-dimensional molecular orientation was thus shown.

  19. Anomalous dispersion of the acoustic mode in liquid Bi

    NASA Astrophysics Data System (ADS)

    Inui, M.; Kajihara, Y.; Munejiri, S.; Hosokawa, S.; Chiba, A.; Ohara, K.; Tsutsui, S.; Baron, A. Q. R.

    2015-08-01

    Inelastic x-ray scattering measurements on liquid Bi were carried out. Prominent acoustic mode excitations were observed in the dynamic structure factor to beyond 12 nm-1, which resolves previously conflicting results as to their presence beyond 6 nm-1. We find the dispersion curve of the excitation energy with momentum transfer is nearly flat from 7 to 15 nm-1 consistent with ab initio calculations of liquid Bi [J. Souto et al., Phys. Rev. B 81, 134201 (2010), 10.1103/PhysRevB.81.134201]. Our ab initio and classical molecular dynamics simulations suggest that a long-range force is needed to reproduce the flatness of the dispersion curve, and the long-range force is correlated with a local structure consisting of shorter and longer bonds in the liquid.

  20. Electron impact excitation of methane

    NASA Technical Reports Server (NTRS)

    Vuskovic, L.; Trajmar, S.

    1983-01-01

    A crossed molecular beam-electron beam apparatus was employed to examine the excitation cross-sections of CH4. Attention was given to 20, 30, and 200 eV impact energies at angles from 8-130 deg. Spectra were obtained in the elastic and inelastic realms as well as in the ionization continuum in the 12.99-15.0 eV energy-loss range. Differential cross-sections were also determined. The results are useful for modeling the behavior of CH4 in planetary atmospheres.

  1. New Modes of Nuclear Excitations

    E-print Network

    Nadia Tsoneva; Horst Lenske

    2013-10-01

    We present a theoretical approach based on density functional theory supplemented by a microscopic multi-phonon model which is applied for investigations of pygmy resonances and other excitations of different multipolarities in stable and exotic nuclei. The possible relation of low-energy modes to the properties of neutron or proton skins is systematically studied in isotonic and isotopic chains. The fine structure of nuclear electric and magnetic response functions is analyzed and compared to experimental data. Their relevance to nuclear astrophysics is discussed.

  2. Vibrationally Excited C$_4$H

    E-print Network

    Cooksy, Andrew L; Killian, T C; Thaddeus, P; Patel, Nimesh A; Young, Ken H; McCarthy, M C

    2015-01-01

    Rotational spectra in four new excited vibrational levels of the linear carbon chain radical C$_4$H radical were observed in the millimeter band between 69 and 364 GHz in a low pressure glow discharge, and two of these were observed in a supersonic molecular beam between 19 and 38 GHz. All have rotational constants within 0.4% of the $^2\\Sigma^+$ ground vibrational state of C$_4$H and were assigned to new bending vibrational levels, two each with $^2\\Sigma$ and $^2\\Pi$ vibrational symmetry. The new levels are tentatively assigned to the $1\

  3. Excited states in 129I

    NASA Astrophysics Data System (ADS)

    Deleanu, D.; Balabanski, D. L.; Venkova, Ts.; Bucurescu, D.; M?rginean, N.; Ganio?lu, E.; C?ta-Danil, Gh.; Atanasova, L.; C?ta-Danil, I.; Detistov, P.; Filipescu, D.; Ghi??, D.; Glodariu, T.; Iva?cu, M.; M?rginean, R.; Mihai, C.; Negret, A.; Pascu, S.; Sava, T.; Stroe, L.; Suliman, G.; Zamfir, N. V.

    2013-01-01

    Excited states in 129I were populated with the 124Sn(7Li,2n) reaction at 23 MeV. In-beam measurements of ?-ray coincidences were performed with an array of eight HPGe detectors and five LaBr3(Ce) scintillation detectors. Based on the ?? coincidence data, a positive parity band structure built on the 7/2+ ground state was established and the ?g7/2 configuration at oblate deformation was assigned to it. The results are compared to interacting Boson-Fermion model (IBFM) and total Routhian surface (TRS) calculations.

  4. [Neurosteroids. Neuromodulators of cerebral excitability].

    PubMed

    Calixto González, E; Brailowsky, S

    1998-01-01

    Steroids which are produced by the brain are called neurosteroids, and they are able to modulate neurotransmissions: GABAergic; glutamatergic; glycinergic, and cholinergic (nicotine receptor). These effects are of short latency and duration, and do not implicate the cellular genome. The interaction of these neurosteroids with membrane receptors contribute to the regulation of neuronal excitability, and their study has allowed a better understanding of cognitive, hormonal, and epileptic phenomena as well as the development of new drugs with anxiolytic, antidepressive, anesthetic and anti-epileptic effects. PMID:9658699

  5. Multiarmed Spirals in Excitable Media

    NASA Astrophysics Data System (ADS)

    Vasiev, Bakthier; Siegert, Florian; Weijer, Cornelis

    1997-03-01

    Numerical studies of the properties of multiarmed spirals show that they can form spontaneously in low excitability media. The maximum number of arms in a multiarmed spiral is proportional to the ratio of the single spiral period to the refractoriness of the medium. Multiarmed spirals are formed due to attraction of single spirals if these spirals rotate in the same direction and their tips are less than one wavelength apart, i.e., a spiral broken not far from its tip can evolve into a 2-armed spiral. We propose this mechanism to be responsible for the formation of multiarmed spirals in mounds of the slime mold Dictyostelium discoideum.

  6. Liquid level detector

    DOEpatents

    Grasso, Albert P. (Vernon, CT)

    1986-01-01

    A liquid level detector for low pressure boilers. A boiler tank, from which apor, such as steam, normally exits via a main vent, is provided with a vertical side tube connected to the tank at the desired low liquid level. When the liquid level falls to the level of the side tube vapor escapes therethrough causing heating of a temperature sensitive device located in the side tube, which, for example, may activate a liquid supply means for adding liquid to the boiler tank. High liquid level in the boiler tank blocks entry of vapor into the side tube, allowing the temperature sensitive device to cool, for example, to ambient temperature.

  7. Liquid level detector

    DOEpatents

    Grasso, A.P.

    1984-02-21

    A liquid level detector for low pressure boilers. A boiler tank, from which vapor, such as steam, normally exits via a main vent, is provided with a vertical side tube connected to the tank at the desired low liquid level. When the liquid level falls to the level of the side tube vapor escapes therethrough causing heating of a temperature sensitive device located in the side tube, which, for example, may activate a liquid supply means for adding liquid to the boiler tank. High liquid level in the boiler tank blocks entry of vapor into the side tube, allowing the temperature sensitive device to cool, for example, to ambient temperature.

  8. Semiconductor nanorod liquid crystals

    SciTech Connect

    Li, Liang-shi; Walda, Joost; Manna, Liberato; Alivisatos, A. Paul

    2002-01-28

    Rodlike molecules form liquid crystalline phases with orientational order and positional disorder. The great majority of materials in which liquid crystalline phases have been observed are comprised of organic molecules or polymers, even though there has been continuing and growing interest in inorganic liquid crystals. Recent advances in the control of the sizes and shapes of inorganic nanocrystals allow for the formation of a broad class of new inorganic liquid crystals. Here we show the formation of liquid crystalline phases of CdSe semiconductor nanorods. These new liquid crystalline phases may have great importance for both application and fundamental study.

  9. Charge transfer reactions in nematic liquid crystals

    SciTech Connect

    Wiederrecht, G.P.; Wasielewski, M.R.; Galili, T.; Levanon, H.

    1998-07-01

    Ultrafast transient absorption studies of intramolecular photoinduced charge separation and thermal charge recombination were carried out on a molecule consisting of a 4-(N-pyrrolidino)naphthalene-1,8-imide donor (PNI) covalently attached to a pyromellitimide acceptor (PI) dissolved in the liquid crystal 4{prime}-(n-pentyl)-4-cyanobiphenyl (5CB). The temperature dependencies of the charge separation and recombination rates were obtained at temperatures above the nematic-isotropic phase transition of 5CB, where ordered microdomains exist and scattering of visible light by these domains is absent. The authors show that excited state charge separation is dominated by molecular reorientation of 5CB perpendicular to the director within the liquid crystal microdomains. They also show that charge recombination is adiabatic and is controlled by the comparatively slow collective reorientation of the liquid crystal microdomains relative to the orientation of PNI{sup +}-PI{sup {minus}}. They also report the results of time resolved electron paramagnetic resonance (TREPR) studies of photoinduced charge separation in a series of supramolecular compounds dissolved in oriented liquid crystal solvents. These studies permit the determination of the radical pair energy levels as the solvent reorganization energy increases from the low temperature crystalline phase, through the soft glass phase, to the nematic phase of the liquid crystal.

  10. Electronic spectra and excited state dynamics of pentafluorophenol: Effects of low-lying ??? states

    NASA Astrophysics Data System (ADS)

    Karmakar, Shreetama; Mukhopadhyay, Deb Pratim; Chakraborty, Tapas

    2015-05-01

    Multiple fluorine atom substitution effect on photophysics of an aromatic chromophore has been investigated using phenol as the reference system. It has been noticed that the discrete vibronic structure of the S1?S0 absorption system of phenol vapor is completely washed out for pentafluorophenol (PFP), and the latter also shows very large Stokes shift in the fluorescence spectrum. For excitations beyond S1 origin, the emission yield of PFP is reduced sharply with increase in excess vibronic energy. However, in a collisional environment like liquid hydrocarbon, the underlying dynamical process that drives the non-radiative decay is hindered drastically. Electronic structure theory predicts a number of low-lying dark electronic states of ??? character in the vicinity of the lowest valence ??? state of this molecule. Tentatively, we have attributed the excitation energy dependent non-radiative decay of the molecule observed only in the gas phase to an interplay between the lowest ??? and a nearby dissociative ??? state. Measurements in different liquids reveal that some of the dark excited states light up with appreciable intensity only in protic liquids like methanol and water due to hydrogen bonding between solute and solvents. Electronic structure theory methods indeed predict that for PFP-(H2O)n clusters (n = 1-11), intensities of a number of ??? states are enhanced with increase in cluster size. In contrast with emitting behavior of the molecule in the gas phase and solutions of nonpolar and polar aprotic liquids, the fluorescence is completely switched off in polar protic liquids. This behavior is a chemically significant manifestation of perfluoro effect, because a very opposite effect occurs in the case of unsubstituted phenol for which fluorescence yield undergoes a very large enhancement in protic liquids. Several dynamical mechanisms have been suggested to interpret the observed photophysical behavior.

  11. Electronic spectra and excited state dynamics of pentafluorophenol: Effects of low-lying ??(?) states.

    PubMed

    Karmakar, Shreetama; Mukhopadhyay, Deb Pratim; Chakraborty, Tapas

    2015-05-14

    Multiple fluorine atom substitution effect on photophysics of an aromatic chromophore has been investigated using phenol as the reference system. It has been noticed that the discrete vibronic structure of the S1?S0 absorption system of phenol vapor is completely washed out for pentafluorophenol (PFP), and the latter also shows very large Stokes shift in the fluorescence spectrum. For excitations beyond S1 origin, the emission yield of PFP is reduced sharply with increase in excess vibronic energy. However, in a collisional environment like liquid hydrocarbon, the underlying dynamical process that drives the non-radiative decay is hindered drastically. Electronic structure theory predicts a number of low-lying dark electronic states of ??(?) character in the vicinity of the lowest valence ??(?) state of this molecule. Tentatively, we have attributed the excitation energy dependent non-radiative decay of the molecule observed only in the gas phase to an interplay between the lowest ??(?) and a nearby dissociative ??(?) state. Measurements in different liquids reveal that some of the dark excited states light up with appreciable intensity only in protic liquids like methanol and water due to hydrogen bonding between solute and solvents. Electronic structure theory methods indeed predict that for PFP-(H2O)n clusters (n = 1-11), intensities of a number of ??(?) states are enhanced with increase in cluster size. In contrast with emitting behavior of the molecule in the gas phase and solutions of nonpolar and polar aprotic liquids, the fluorescence is completely switched off in polar protic liquids. This behavior is a chemically significant manifestation of perfluoro effect, because a very opposite effect occurs in the case of unsubstituted phenol for which fluorescence yield undergoes a very large enhancement in protic liquids. Several dynamical mechanisms have been suggested to interpret the observed photophysical behavior. PMID:25978887

  12. Zero gravity liquid mixer

    NASA Technical Reports Server (NTRS)

    Booth, F. W.; Bruce, R. A. (inventors)

    1973-01-01

    An apparatus for mixing liquids under conditions of zero gravity is disclosed. The apparatus is comprised of a closed reservoir for the liquids, with a means for maintaining a positive pressure on the liquids in the reservoir. A valved liquid supply line is connected to the reservoir for supplying the reservoir with the liquids to be mixed in the reservoir. The portion of the reservoir containing the liquids to be mixed is in communication with a pump which alternately causes a portion of the liquids to flow out of the pump and into the reservoir to mix the liquids. The fluids in the reservoir are in communication through a conduit with the pump which alternately causes a portion of the fluids to flow out of the pump and into the sphere. The conduit connecting the pump and sphere may contain a nozzle or other jet-forming structure such as a venturi for further mixing the fluids.

  13. High Performance Liquid Chromatography

    E-print Network

    Nizkorodov, Sergey

    HPLC - 1 High Performance Liquid Chromatography HPLC MEASUREMENT OF POLYCYCLIC AROMATIC HYDROCARBONS IN CIGARETTE SMOKE Last updated: June 17, 2014 #12;HPLC - 2 High Performance Liquid Chromatography identify as many PAH as possible in cigarette smoke using high performance liquid chromatography (HPLC

  14. Making Liquid Oxygen

    E-print Network

    French, M M J

    2010-01-01

    In this article I explain in detail a method for making small amounts of liquid oxygen in the classroom if there is no access to a cylinder of compressed oxygen gas. I also discuss two methods for identifying the fact that it is liquid oxygen as opposed to liquid nitrogen.

  15. Breakup of Liquid Filaments

    E-print Network

    Castrejon-Pita, Alfonso A.; Castrejon-Pita, J. R.; Hutchings, I. M.

    2012-01-01

    Charles Babbage Road, Cambridge, CB3 0FS, U.K. Whether a thin filament of liquid separates into two or more droplets or eventually condenses lengthwise to form a single larger drop depends on the liquid’s density, viscosity and surface tension...

  16. Renewable liquid reflection grating

    DOEpatents

    Ryutov, Dmitri D.; Toor, Arthur

    2003-10-07

    A renewable liquid reflection grating. Electrodes are operatively connected to a conducting liquid in an arrangement that produces a reflection grating and driven by a current with a resonance frequency. In another embodiment, the electrodes create the grating by a resonant electrostatic force acting on a dielectric liquid.

  17. Liquid detection circuit

    DOEpatents

    Regan, Thomas O. (North Aurora, IL)

    1987-01-01

    Herein is a circuit which is capable of detecting the presence of liquids, especially cryogenic liquids, and whose sensor will not overheat in a vacuum. The circuit parameters, however, can be adjusted to work with any liquid over a wide range of temperatures.

  18. Dynamics of fractionalization in quantum spin liquids

    NASA Astrophysics Data System (ADS)

    Knolle, J.; Kovrizhin, D. L.; Chalker, J. T.; Moessner, R.

    2015-09-01

    We present the theory of dynamical spin response for the Kitaev honeycomb model, obtaining exact results for the structure factor (SF) in gapped and gapless, Abelian and non-Abelian quantum spin-liquid (QSL) phases. We also describe the advances in methodology necessary to compute these results. The structure factor shows signatures of spin fractionalization into emergent quasiparticles: Majorana fermions and fluxes of Z2 gauge field. In addition to a broad continuum from spin fractionalization, we find sharp (? -function) features in the response. These arise in two distinct ways: from excited states containing only (static) fluxes and no (mobile) fermions, and from excited states in which fermions are bound to fluxes. The SF is markedly different in Abelian and non-Abelian QSLs, and bound fermion-flux composites appear only in the non-Abelian phase.

  19. Excited Baryons in Holographic QCD

    SciTech Connect

    de Teramond, Guy F.; Brodsky, Stanley J.; /SLAC /Southern Denmark U., CP3-Origins

    2011-11-08

    The light-front holographic QCD approach is used to describe baryon spectroscopy and the systematics of nucleon transition form factors. Baryon spectroscopy and the excitation dynamics of nucleon resonances encoded in the nucleon transition form factors can provide fundamental insight into the strong-coupling dynamics of QCD. The transition from the hard-scattering perturbative domain to the non-perturbative region is sensitive to the detailed dynamics of confined quarks and gluons. Computations of such phenomena from first principles in QCD are clearly very challenging. The most successful theoretical approach thus far has been to quantize QCD on discrete lattices in Euclidean space-time; however, dynamical observables in Minkowski space-time, such as the time-like hadronic form factors are not amenable to Euclidean numerical lattice computations.

  20. Excitation of interstellar hydrogen chloride

    NASA Technical Reports Server (NTRS)

    Neufild, David A.; Green, Sheldon

    1994-01-01

    We have computed new rate coefficients for the collisional excitation of HCl by He, in the close-coupled formalism and using an interaction potential determined recently by Willey, Choong, & DeLucia. Results have been obtained for temperatures between 10 K and 300 K. With the use of the infinite order sudden approximation, we have derived approximate expressions of general applicability which may be used to estimate how the rate constant for a transition (J to J prime) is apportioned among the various hyperfine states F prime of the final state J prime. Using these new rate coefficients, we have obtained predictions for the HCl rotational line strengths expected from a dense clump of interstellar gas, as a function of the HCl fractional abundance. Over a wide range of HCl abundances, we have found that the line luminosities are proportional to abundance(exp 2/3), a general result which can be explained using a simple analytical approximation. Our model for the excitation of HCl within a dense molecular cloud core indicates that the J = 1 goes to 0 line strengths measured by Blake, Keene, & Phillips toward the Orion Molecular Cloud (OMC-1) imply a fractional abundance n(HCl)/n(H2) approximately 2 x 10(exp -9), a value which amounts to only approximately 0.3% of the cosmic abundance of chlorine nuclei. Given a fractional abundance of 2 x 10(exp -9), the contribution of HCl emission to the total radiative cooling of a dense clump is small. For Orion, we predict a flux approximately 10(exp -19) W/sq cm for the HCl J = 3 goes to 2 line near 159.8 micrometers, suggesting that the strength of this line could be measured using the Infrared Space Observatory.

  1. Longitudinal RF excitation of carbon dioxide lasers

    NASA Astrophysics Data System (ADS)

    Jirmann, J.

    1986-01-01

    Longitudinal RF excitation of CO2-lasers at relatively low radio frequencies in the 100 to 200 kHz range permits an efficient ac to RF conversion in the power supply while maintaining all the advantages of RF excited lasers. Existing tube designs for dc excitations can be easily modified, and peripheral circuitry like laser stabilizers remain useable too. Experimental results for a prototype laser are given.

  2. Excited Quark Production at Future $?p$ Colliders

    E-print Network

    R. Ciftci

    2008-03-16

    Excited quark production at future $\\gamma p$ colliders is studied. Namely, $\\gamma p \\to q^{*}X$ with subsequent $q^{*}\\to gq$ and $\\gamma q $ decay channels are considered. Signatures for discovery of the excited quark and corresponding standard model backgrounds are discussed in detail. Discovery limits for excited quark masses and achievable values of compositeness parameters $f_s$, $f$ and $f^\\prime $ are determined.

  3. Gross violation of the Wiedemann–Franz law in a quasi-one-dimensional conductor

    PubMed Central

    Wakeham, Nicholas; Bangura, Alimamy F.; Xu, Xiaofeng; Mercure, Jean-Francois; Greenblatt, Martha; Hussey, Nigel E.

    2011-01-01

    When charge carriers are spatially confined to one dimension, conventional Fermi-liquid theory breaks down. In such Tomonaga–Luttinger liquids, quasiparticles are replaced by distinct collective excitations of spin and charge that propagate independently with different velocities. Although evidence for spin–charge separation exists, no bulk low-energy probe has yet been able to distinguish successfully between Tomonaga–Luttinger and Fermi-liquid physics. Here we show experimentally that the ratio of the thermal and electrical Hall conductivities in the metallic phase of quasi-one-dimensional Li0.9Mo6O17 diverges with decreasing temperature, reaching a value five orders of magnitude larger than that found in conventional metals. Both the temperature dependence and magnitude of this ratio are consistent with Tomonaga–Luttinger liquid theory. Such a dramatic manifestation of spin–charge separation in a bulk three-dimensional solid offers a unique opportunity to explore how the fermionic quasiparticle picture recovers, and over what time scale, when coupling to a second or third dimension is restored. PMID:21772267

  4. Radiation monitor for liquids

    DOEpatents

    Koster, J.E.; Bolton, R.D.

    1999-03-02

    A radiation monitor for use with liquids that utilizes air ions created by alpha radiation emitted by the liquids as its detectable element. A signal plane, held at an electrical potential with respect to ground, collects these air ions. A guard plane or guard rings is used to limit leakage currents. In one embodiment, the monitor is used for monitoring liquids retained in a tank. Other embodiments monitor liquids flowing through a tank, and bodies of liquids, such as ponds, lakes, rivers and oceans. 4 figs.

  5. Rydberg excitation of Bose-Einstein condensates

    E-print Network

    Rolf Heidemann; Ulrich Raitzsch; Vera Bendkowsky; Björn Butscher; Robert Löw; Tilman Pfau

    2007-10-30

    Rydberg atoms provide a wide range of possibilities to tailor interactions in a quantum gas. Here we report on Rydberg excitation of Bose-Einstein condensed 87Rb atoms. The Rydberg fraction was investigated for various excitation times and temperatures above and below the condensation temperature. The excitation is locally blocked by the van der Waals interaction between Rydberg atoms to a density-dependent limit. Therefore the abrupt change of the thermal atomic density distribution to the characteristic bimodal distribution upon condensation could be observed in the Rydberg fraction. The observed features are reproduced by a simulation based on local collective Rydberg excitations.

  6. Liquid Wall Chambers

    SciTech Connect

    Meier, W R

    2011-02-24

    The key feature of liquid wall chambers is the use of a renewable liquid layer to protect chamber structures from target emissions. Two primary options have been proposed and studied: wetted wall chambers and thick liquid wall (TLW) chambers. With wetted wall designs, a thin layer of liquid shields the structural first wall from short ranged target emissions (x-rays, ions and debris) but not neutrons. Various schemes have been proposed to establish and renew the liquid layer between shots including flow-guiding porous fabrics (e.g., Osiris, HIBALL), porous rigid structures (Prometheus) and thin film flows (KOYO). The thin liquid layer can be the tritium breeding material (e.g., flibe, PbLi, or Li) or another liquid metal such as Pb. TLWs use liquid jets injected by stationary or oscillating nozzles to form a neutronically thick layer (typically with an effective thickness of {approx}50 cm) of liquid between the target and first structural wall. In addition to absorbing short ranged emissions, the thick liquid layer degrades the neutron flux and energy reaching the first wall, typically by {approx}10 x x, so that steel walls can survive for the life of the plant ({approx}30-60 yrs). The thick liquid serves as the primary coolant and tritium breeding material (most recent designs use flibe, but the earliest concepts used Li). In essence, the TLW places the fusion blanket inside the first wall instead of behind the first wall.

  7. Liquid Metal Transformers

    E-print Network

    Sheng, Lei; Liu, Jing

    2014-01-01

    The room temperature liquid metal is quickly emerging as an important functional material in a variety of areas like chip cooling, 3D printing or printed electronics etc. With diverse capabilities in electrical, thermal and flowing behaviors, such fluid owns many intriguing properties that had never been anticipated before. Here, we show a group of unconventional phenomena occurring on the liquid metal objects. Through applying electrical field on the liquid metals immersed in water, a series of complex transformation behaviors such as self-assembling of a sheet of liquid metal film into a single sphere, quick mergences of separate metal droplets, controlled self-rotation and planar locomotion of liquid metal objects can be realized. Meanwhile, it was also found that two accompanying water vortexes were induced and reliably swirled near the rotating liquid metal sphere. Further, effects of the shape, size, voltage, orientation and geometries of the electrodes to control the liquid metal transformers were clar...

  8. Liquid Propellant Manipulated Acoustically

    NASA Technical Reports Server (NTRS)

    Oeftering, Richard C.; Chato, David J.; Mann, Adin, III

    2003-01-01

    Fluids are difficult to manage in the space environment. Without gravity, the liquid and gas do not always remain separated as they do in the 1g environment of Earth. Instead the liquid and gas volumes mix and migrate under the influence of surface tension, thermodynamic forces, and external disturbances. As a result, liquid propellants may not be in a useable location or may even form a chaotic mix of liquid and gas bubbles. In the past, mechanical pumps, baffles, and a variety of specialized passive devices have been used to control the liquid and gas volumes. These methods need to be carefully tuned to a specific configuration to be effective. With increasing emphasis on long-term human activity in space there is a trend toward liquid systems that are more flexible and provide greater control. We are exploring new methods of manipulating liquids by using the nonlinear acoustic effects achieved by using beams of highly directed high-intensity acoustic waves.

  9. Structural Transitions at Ionic Liquid Interfaces.

    PubMed

    Rotenberg, Benjamin; Salanne, Mathieu

    2015-12-17

    Recent advances in experimental and computational techniques have allowed for an accurate description of the adsorption of ionic liquids on metallic electrodes. It is now well-established that they adopt a multilayered structure and that the composition of the layers changes with the potential of the electrode. In some cases, potential-driven ordering transitions in the first adsorbed layer have been observed in experiments probing the interface on the molecular scale or by molecular simulations. This perspective gives an overview of the current understanding of such transitions and of their potential impact on the physical and (electro)chemical processes at the interface. In particular, peaks in the differential capacitance, slow dynamics at the interface, and changes in the reactivity have been reported in electrochemical studies. Interfaces between ionic liquids and metallic electrodes are also highly relevant for their friction properties, the voltage-dependence of which opens the way to exciting applications. PMID:26722704

  10. Heavy fermion spin liquid in herbertsmithite

    NASA Astrophysics Data System (ADS)

    Shaginyan, V. R.; Amusia, M. Ya.; Msezane, A. Z.; Popov, K. G.; Stephanovich, V. A.

    2015-09-01

    We analyze recent heat capacity measurements in herbertsmithite ZnCu3(OH)6Cl2 single crystal samples subjected to strong magnetic fields. We show that the temperature dependence of specific heat Cmag formed by quantum spin liquid at different magnetic fields B resembles the electronic heat capacity Cel of the HF metal YbRh2Si2. We demonstrate that the spinon effective mass Mmag* ?Cmag / T exhibits a scaling behavior like that of Cel / T. We also show that the recent measurements of Cmag are compatible with those obtained on powder samples. These observations allow us to conclude that ZnCu3(OH)6Cl2 holds a stable strongly correlated quantum spin liquid, and a possible gap in the spectra of spinon excitations is absent even under the application of very high magnetic fields of 18 T.

  11. Electro-optical parameters in excited states of some spectrally active molecules

    NASA Astrophysics Data System (ADS)

    Benchea, Andreea Celia; Closca, Valentina; Rusu, Cristina Marcela; Morosanu, Cezarina; Dorohoi, Dana Ortansa

    2014-08-01

    The spectral shifts measured in different solvents are expressed as functions of the solvent macroscopic parameters. The value of the correlation coefficient multiplying the functions of electric permittivity was determined by statistical means. The correlation coefficient depends on the electric dipole moment of the spectrally active molecules. The electro-optical parameters in the ground state of the solute molecules can be approximated by molecular modeling. The excited state parameters are usually estimated using the results obtained both by HyperChem Programme and solvatochromic study. The importance of this approximate method is that it offers information about of the excited state of solute molecule for which our measuring possibilities are very restrictive. The information about the excited electronic state is affected by the limits in which the theories of liquid solutions are developed. Our results refer to two molecules of vitamins from B class, namely B3 and B6.

  12. Intensification of Liquid-Liquid Contacting Processes

    E-print Network

    Qiu, Zheyan

    2010-09-01

    transfer was intensified by the application of electric fields. As an alternative biofuel, biodiesel is produced through transesterification of vegetable oils, fat and algae lipids and alcohol with the help of acid or base. Transesterification is a liquid...

  13. Optimization of Two-photon Excited Fluorescence Enhancement between Tunable and Broadband Femtosecond Laser Pulse Excitations 

    E-print Network

    Wang, Chao

    2012-02-14

    This project explores optimization of two-photon excited fluorescence (TPEF) enhancement between tunable narrowband and un-tuned broadband femtosecond (fs) laser pulse excitations for two-photon microscopy (TPM). The research is conducted...

  14. Modeling Liquid-Liquid Equilibrium of Ionic Liquid Systems with NRTL, Electrolyte-NRTL, and UNIQUAC

    E-print Network

    Stadtherr, Mark A.

    temperature ionic liquids (ILs). ILs are generally defined as organic salts with melting temperatures belowModeling Liquid-Liquid Equilibrium of Ionic Liquid Systems with NRTL, Electrolyte-NRTL, and UNIQUAC: markst@nd.edu #12;Abstract Characterization of liquid-liquid equilibrium (LLE) in system containing ionic

  15. Intense Infrared Scintillation of Liquid Ar-Xe Mixtures

    E-print Network

    Neumeier, A; Heindl, T; Himpsl, A; Hagn, H; Hofmann, M; Oberauer, L; Potzel, W; Roth, S; Schönert, S; Wieser, J; Ulrich, A

    2015-01-01

    Intense infrared (IR) light emission from liquid Ar-Xe mixtures has been observed using 12 keV electron-beam excitation. The emission peaks at a wavelength of 1.18 $\\mu$m and the half-width of the emission band is 0.1 $\\mu$m. Maximum intensity has been found for a 10 ppm xenon admixture in liquid argon. The conversion efficiency of electron beam-power to IR-light is about 1% (10000 photons per MeV electron energy deposited). A possible application of this intense IR emission for a new particle discrimination concept in liquid noble gas detectors is discussed. No light emission was found for perfectly purified liquid argon in the wavelength range from 0.5 to 3.5 $\\mu$m on the current level of sensitivity.

  16. In situ TEM of Biological Assemblies in Liquid

    PubMed Central

    McDonald, Sarah M.; Kelly, Deborah F.

    2013-01-01

    Researchers regularly use Transmission Electron Microscopes (TEMs) to examine biological entities and to assess new materials. Here, we describe an additional application for these instruments- viewing viral assemblies in a liquid environment. This exciting and novel method of visualizing biological structures utilizes a recently developed microfluidic-based specimen holder. Our video article demonstrates how to assemble and use a microfluidic holder to image liquid specimens within a TEM. In particular, we use simian rotavirus double-layered particles (DLPs) as our model system. We also describe steps to coat the surface of the liquid chamber with affinity biofilms that tether DLPs to the viewing window. This permits us to image assemblies in a manner that is suitable for 3D structure determination. Thus, we present a first glimpse of subviral particles in a native liquid environment. PMID:24429390

  17. Ultrasonic, Non-Invasive Classification/Discrimination of Liquid Explosives (LEs) and Threat Liquids from Non-Threat Liquids in Sealed Containers

    SciTech Connect

    Diaz, Aaron A.; Cinson, Anthony D.; Tucker, Brian J.; Samuel, Todd J.; Morales, Romarie

    2009-07-20

    Government agencies and homeland security organizations are searching for more effective approaches for dealing with the increasing demand for inspections involving potential threat liquids and hazardous chemicals, including liquid explosives (LEs). The quantity and variability of hand-held and cargo-sized containers being shipped worldwide drives the need for rapid and effective ways for conducting non-intrusive inspections of liquid-filled containers of a diverse range of types, shapes and sizes. Such inspections need to quickly classify/discriminate between liquids within containers and also ascertain the presence of unexpected objects within a container. The science base, methodology and prototype device for classification/discrimination between classes of liquids has been developed. The Pacific Northwest National Laboratory (PNNL) has developed a methodology and prototype device for classification/discrimination of a wide variety of liquids (including threat liquids and their precursors), providing noninvasive liquid classification/discrimination capabilities using a nondestructive ultrasonic measurement approach for inspecting sealed containers. The Container Screening Device (CSD) employs frequency-modulated (FM) chirp excitation and pulse-compression signal processing techniques to measure ultrasonic velocity and a relative attenuation value for liquids within a container, and is capable of determining other acoustic properties from through-transmission, contact measurements over a wide frequency range. Recent algorithm developments are beginning to address the issues of container wall variations and thickness. A description of the basic science, measurement approach and sources of variability in the measurement will be presented and laboratory measurements acquired from a suite of commercial products and precursor liquids used in the manufacturing of Homemade Explosives (HMEs) will be given.

  18. Fast Laser Excitation and Ultrahigh Strain-Rate Deformation

    SciTech Connect

    Robert Averback

    2007-06-03

    Phase evolution induced by single or repeated excitation with energetic femtosecond laser pulses is examined. Of primary interest is the solidification behavior of pure metals at deep undercoolings and self-organization in simple eutectic alloys. Time resolved measurements using third harmonic generation (THG) of light and ultrafast electron diffraction (UED) are employed to elucidate several issues related to fast laser excitation, including heat transport by ballistic and diffusional electrons through multilayer films, the dependence of crystallization velocities on materials properties, mechanisms controlling the transport of heat away from the crystal-liquid interface, and the possibility for quenching pure metals, such as Cu, Ni, and Fe, into the amorphous state. Special samples designed to maximize the quenching speed are developed. The properties of such pure metallic glasses, such as glass and crystallization temperatures, will be measured, if such samples are successfully produced. The measurements are complemented by molecular dynamics computer simulations of the solidification process. The second interest of this research is mesoscopic, self-organization of materials under repeated laser melting, with diffusional relaxation between pulses. We select binary alloys that are immiscible in the solid state but miscible in the liquid state, such as Ag-Cu. Femtosecond laser irradiation is employed to induce melting and to vary the melting time over a wide range, from a few ps to hundreds of ps. This enables us to perform critical experimental tests of key theoretical predictions self-organization in alloys under external forcing, in particular the existence of a threshold value of the forced mixing length for patterning to take place.

  19. Vibrationally excited molecular hydrogen near Herschel 36

    SciTech Connect

    Rachford, Brian L.; Snow, Theodore P.; Ross, Teresa L.

    2014-05-10

    We present the first high resolution UV spectra toward Herschel 36, a Trapezium-like system of high-mass stars contained within the Lagoon Nebula (M8, NGC 6523). The spectra reveal extreme rovibrational excitation of molecular hydrogen in material at a single velocity or very small range of velocities, with this component presumably lying near the star system and undergoing fluorescent excitation. The overall H{sub 2} excitation is similar to, but apparently larger than, that seen toward HD 37903 which previously showed the largest vibrationally excited H{sub 2} column densities seen in UV absorption spectra. While the velocities of the highly excited H{sub 2} lines are consistent within each observation, it appears that they underwent a ?60 km s{sup –1} redshift during the 3.6 yr between observations. In neither case does the velocity of the highly excited material match the velocity of the bulk of the line-of-sight material which appears to mostly be in the foreground of M8. Recent work shows unusually excited CH and CH{sup +} lines and several unusually broad diffuse interstellar bands toward Herschel 36. Along with the H{sub 2} excitation, all of these findings appear to be related to the extreme environment within ?0.1 pc of the massive young stellar system.

  20. Excitation of helium ion by positron impact

    SciTech Connect

    Khan, P.; Ghosh, A.S.

    1986-01-01

    Three (1s,2s,2p) and five (1s,2s,2p,3s-bar,3p-bar) -state close-coupling methods have been employed to calculate the n = 2 excitation cross sections of helium ion by positron impact. The effect of pseudostate is found to be very pronounced in the case of 1s-2s excitation.

  1. What Gets a Cell Excited? Kinky Curves

    ERIC Educational Resources Information Center

    Kay, Alan R.

    2014-01-01

    Hodgkin and Huxley's (5) revealing the origins of cellular excitability is one of the great triumphs of physiology. In an extraordinarily deft series of papers, they were able to measure the essential electrical characteristics of neurons and synthesize them into a quantitative model that accounts for the excitability of neurons and other…

  2. Study of excited nucleons and their structure

    SciTech Connect

    Burkert, Volker D.

    2014-01-01

    Recent advances in the study of excited nucleons are discussed. Much of the progress has been achieved due to the availability of high precision meson production data in the photoproduction and electroproduction sectors, the development of multi-channel partial wave analysis techniques, and advances in Lattice QCD with predictions of the full excitation spectrum.

  3. The Excitation Spectrum for Weakly Interacting Bosons

    E-print Network

    Robert Seiringer

    2010-09-17

    We investigate the low energy excitation spectrum of a Bose gas with weak, long range repulsive interactions. In particular, we prove that the Bogoliubov spectrum of elementary excitations with linear dispersion relation for small momentum becomes exact in the mean-field limit.

  4. Nuclear excitations and reaction mechanisms

    SciTech Connect

    Fallieros, S.; Levin, F.S.

    1990-08-01

    The main theme of this report is the study and interpretation of the sequence of events that occur during the collisions of nuclear particles. Some of the processes discussed in parts A and B involve short range interactions; others involve interactions of long range. In most of part A one of the particles in the initial or in the final state (or in both) is a photon, which serves as a probe of the second particle, which may be a nucleus, a proton, a pion or any other hadron. The complexity of the processes taking place during the collisions makes it necessary to simplify some aspects of the physical problem. This leads to the introduction of modals which are used to describe a limited number of features in as much detail as possible. The main interest is the understanding of the hadronic excitations which result from the absorption of a photon and the determination of the fundamental structure constants of the target particle. In part B, all the particles are hadrons. The purpose here is to develop and apply optimal quantal methods appropriate for describing the interacting systems. Of particular interest are three-particle collision systems in which the final state consists of three free particles. Part B also considers the process of nuclear fusion as catalyzed by bound muons.

  5. Final excitation energy of fission fragments

    E-print Network

    Karl-Heinz Schmidt; Beatriz Jurado

    2011-04-14

    We study how the excitation energy of the fully accelerated fission fragments is built up. It is stressed that only the intrinsic excitation energy available before scission can be exchanged between the fission fragments to achieve thermal equilibrium. This is in contradiction with most models used to calculate prompt neutron emission where it is assumed that the total excitation energy of the final fragments is shared between the fragments by the condition of equal temperatures. We also study the intrinsic excitation-energy partition according to a level density description with a transition from a constant-temperature regime to a Fermi-gas regime. Complete or partial excitation-energy sorting is found at energies well above the transition energy.

  6. Gluonic Excitations and Experimental Hall-D at Jefferson Lab

    SciTech Connect

    Stevens, Justin

    2014-07-01

    A new tagged photon beam facility is being constructed in experimental Hall-D at Jefferson Lab as a part of the 12 GeV upgrade program. The 9 GeV linearly-polarized photon beam will be produced via coherent Bremsstrahlung using the CEBAF electron beam, incident on a diamond radiator. The GlueX experiment in Hall-D will use this photon beam to search for and study the pattern of gluonic excitations in the meson spectrum produced through photoproduction reactions with a liquid hydrogen target. Recent lattice QCD calculations predict a rich spectrum of hybrid mesons, that are formed by exciting the gluonic field that couples the quarks. A subset of these hybrid mesons are predicted to have exotic quantum numbers which cannot be formed from a simple qq^- pair, and thus provide an ideal laboratory for testing QCD in the confinement regime. In these proceedings the status of the construction and installation of the GlueX detector will be presented, in addition to simulation results for some reactions of interest in hybrid meson searches.

  7. Fluorescence Spectrum and Decay Measurement for Hsil VS Normal Cytology Differentiation in Liquid Pap Smear Supernatant

    NASA Astrophysics Data System (ADS)

    Vaitkuviene, A.; Gegzna, V.; Juodkazis, S.; Jursenas, S.; Miasojedovas, S.; Kurtinaitiene, R.; Rimiene, J.; Vaitkus, J.

    2009-06-01

    Cervical smear material contains endo and exocervical cells, mucus and inflammative, immune cells in cases of pathology. Just not destroyed keratinocytes lay on the glass for microscopy. Liquid cytology supernatant apart other diagnostics could be used for photodiagnostic. The spectroscopic parameters suitable for Normal and HSIL cytology groups supernatant differentiation are demonstrated. The dried liquid PAP supernatant fractions—sediment and liquid were investigated. Excitation and emission matrices (EEM), supernatant fluorescence decay measured under 280 nm diode short pulse excitation and fluorescence spectroscopy by excitation with 355 nm laser light were analyzed. The differences between Normal and HSIL groups were statistically proven in the certain spectral regions. Fluorescence decay peculiarities show spectral regions consisting of few fluorophores. Obtained results on fluorescence differences in Normal and HSIL groups' supernatant shows the potency of photodiagnosis application in cervical screening.

  8. Impact of ground- and excited-state aromaticity on cyclopentadiene and silole excitation energies and excited-state polarities.

    PubMed

    Jorner, Kjell; Emanuelsson, Rikard; Dahlstrand, Christian; Tong, Hui; Denisova, Aleksandra V; Ottosson, Henrik

    2014-07-21

    A new qualitative model for estimating the properties of substituted cyclopentadienes and siloles in their lowest ??* excited states is introduced and confirmed through quantum chemical calculations, and then applied to explain earlier reported experimental excitation energies. According to our model, which is based on excited-state aromaticity and antiaromaticity, siloles and cyclopentadienes are cross-hyperconjugated "aromatic chameleons" that adapt their electronic structures to conform to the various aromaticity rules in different electronic states (Hückel's rule in the ?(2) electronic ground state (S0) and Baird's rule in the lowest ??* excited singlet and triplet states (S1 and T1)). By using pen-and-paper arguments, one can explain polarity changes upon excitation of substituted cyclopentadienes and siloles, and one can tune their lowest excitation energies by combined considerations of ground- and excited-state aromaticity/antiaromaticity effects. Finally, the "aromatic chameleon" model can be extended to other monocyclic compound classes of potential use in organic electronics, thereby providing a unified view of the S0, T1, and S1 states of a range of different cyclic cross-?-conjugated and cross-hyperconjugated compound classes. PMID:25043523

  9. Electrically actuated liquid iris.

    PubMed

    Xu, Miao; Ren, Hongwen; Lin, Yi-Hsin

    2015-03-01

    We report an adaptive iris using dielectric liquids and a radial-interdigitated electrode. A black liquid is confined by a circular gasket with a donut shape. The surrounding of the black liquid is filled with an immiscible liquid. In the relaxing state, the black liquid obtains the largest clear aperture. By applying a voltage, the surface of the black liquid is stretched by the generated dielectric force, resulting in a reduction of its aperture. For the demonstrated iris, the diameter of the aperture can be changed from ?4.7??mm to ?1.2??mm when the voltage is applied from 0 to 70??V(rms). The aperture ratio is ?94%. Owing to the radial-interdigitated electrode, the aperture size of the iris can be effectively switched with a reasonably fast response time. The optical switch is polarization-insensitive. The potential applications of our iris are light shutters, optical attenuators, biomimicry, and wearable devices. PMID:25723444

  10. Liquid level detector

    DOEpatents

    Tshishiku, Eugene M. (Augusta, GA)

    2011-08-09

    A liquid level detector for conductive liquids for vertical installation in a tank, the detector having a probe positioned within a sheath and insulated therefrom by a seal so that the tip of the probe extends proximate to but not below the lower end of the sheath, the lower end terminating in a rim that is provided with notches, said lower end being tapered, the taper and notches preventing debris collection and bubble formation, said lower end when contacting liquid as it rises will form an airtight cavity defined by the liquid, the interior sheath wall, and the seal, the compression of air in the cavity preventing liquid from further entry into the sheath and contact with the seal. As a result, the liquid cannot deposit a film to form an electrical bridge across the seal.

  11. Monogroove liquid heat exchanger

    NASA Technical Reports Server (NTRS)

    Brown, Richard F. (Inventor); Edelstein, Fred (Inventor)

    1990-01-01

    A liquid supply control is disclosed for a heat transfer system which transports heat by liquid-vapor phase change of a working fluid. An assembly (10) of monogroove heat pipe legs (15) can be operated automatically as either heat acquisition devices or heat discharge sources. The liquid channels (27) of the heat pipe legs (15) are connected to a reservoir (35) which is filled and drained by respective filling and draining valves (30, 32). Information from liquid level sensors (50, 51) on the reservoir (35) is combined (60) with temperature information (55) from the liquid heat exchanger (12) and temperature information (56) from the assembly vapor conduit (42) to regulate filling and draining of the reservoir (35), so that the reservoir (35) in turn serves the liquid supply/drain needs of the heat pipe legs (15), on demand, by passive capillary action (20, 28).

  12. Ultrasonic level sensors for liquids under high pressure

    NASA Technical Reports Server (NTRS)

    Zuckerwar, A. J.; Mazel, D. S.; Hodges, D. Y.

    1986-01-01

    An ultrasonic level sensor of novel design continuously measures the level of a liquid subjected to a high pressure (up to about 40 MPa), as is sometimes required for the effective transfer of the liquid. The sensor operates as a composite resonator fabricated from a standard high-pressure plug. A flat-bottom hole is machined into the plug along its center line. An ultrasonic transducer is bonded rigidly to the interior surface of the bottom wall, while the exterior surface is in contact with the liquid. Although the bottom wall is designed to satisfy the pressure code, it is still sufficiently thin to permit ready excitation of the axisymmetric plate modes of vibration. The liquid level is measured by a conventional pulse-echo technique. A prototype sensor was tested successfully in a 2300-l water vessel at pressures up to about 37 MPa. A spectral analysis of the transmitted pulse reveals that the flexural, extensional, thickness-shear, and radial plate modes are excited into vibration, but none of these appears to be significantly affected by the pressurization of the liquid.

  13. Liquid level sensor

    SciTech Connect

    Terhune, J. H.; Neissel, J. P.

    1985-06-04

    A liquid level detector, or detector array, for insertion into the pressure vessel of a nuclear reactor, or into any liquid-containing vessel, for that matter. A coaxial cable supports the detector, which includes a sensing element having a positive temperature-coefficient of electrical resistivity. The detector is driven by a constant current source of electricity and the presence of liquid is determined by making a resistance measurement.

  14. Liquid-Liquid Two-Phase Flow Systems Neima Brauner

    E-print Network

    Brauner, Neima

    2.22.2323 1 #12;Liquid-Liquid Two-Phase Flow Systems Neima Brauner School of Engineering, Tel-Aviv University Tel-Aviv 69978, Israel 1 General Description of Liquid-Liquid Flows: Flow Patterns Flows of two immiscible liquids are encountered in a diverse range of processes and equipments. In particular

  15. SSI effects for a tank containing two liquids

    SciTech Connect

    Tang, Yu

    1994-06-01

    Following a brief review of a mechanical model which permits consideration of the flexibility of the tank wall and the supporting medium, the effects of the soil-structure interaction on the dynamic response of a laterally excited tank that contains two liquids are examined. The quantities examined include the hydrodynamic pressure, base shear and moments. The results are compared with those obtained with no soil-structure interaction. Only the impulsive component of response is examined; the convective component is for all practical purposes unaffected by soil-structure interaction. It is shown that for the conditions considered, soil-structure interaction reduces the peak response of the tank-liquid system.

  16. Surface waves on non-Newtonian viscoelastic liquids

    NASA Astrophysics Data System (ADS)

    Ohmasa, Y.; Yao, M.

    2011-03-01

    In the present work, we study the dynamics of thermally excited fluctuations on the surface of non-Newtonian viscoelastic liquids, which shows complex behaviors such as crossover between the capillary wave and the elastic wave, and the coexistence of several modes. We show that the power spectrum is separated into surface localized modes and the bulk shear modes, and they are decomposed further into several modes using the partial fraction expansion. The peak positions of these modes are characterized by roots of a polynomial equation. We calculate the decomposition of the surface wave spectra numerically, and discuss evolution of constituent peaks with liquid parameters.

  17. Surface waves on non-Newtonian viscoelastic liquids.

    PubMed

    Ohmasa, Y; Yao, M

    2011-03-01

    In the present work, we study the dynamics of thermally excited fluctuations on the surface of non-Newtonian viscoelastic liquids, which shows complex behaviors such as crossover between the capillary wave and the elastic wave, and the coexistence of several modes. We show that the power spectrum is separated into surface localized modes and the bulk shear modes, and they are decomposed further into several modes using the partial fraction expansion. The peak positions of these modes are characterized by roots of a polynomial equation. We calculate the decomposition of the surface wave spectra numerically, and discuss evolution of constituent peaks with liquid parameters. PMID:21517511

  18. Liquid Metal Transformers

    E-print Network

    Lei Sheng; Jie Zhang; Jing Liu

    2014-01-30

    The room temperature liquid metal is quickly emerging as an important functional material in a variety of areas like chip cooling, 3D printing or printed electronics etc. With diverse capabilities in electrical, thermal and flowing behaviors, such fluid owns many intriguing properties that had never been anticipated before. Here, we show a group of unconventional phenomena occurring on the liquid metal objects. Through applying electrical field on the liquid metals immersed in water, a series of complex transformation behaviors such as self-assembling of a sheet of liquid metal film into a single sphere, quick mergences of separate metal droplets, controlled self-rotation and planar locomotion of liquid metal objects can be realized. Meanwhile, it was also found that two accompanying water vortexes were induced and reliably swirled near the rotating liquid metal sphere. Further, effects of the shape, size, voltage, orientation and geometries of the electrodes to control the liquid metal transformers were clarified. Such events are hard to achieve otherwise on rigid metal or conventional liquid spheres. This finding has both fundamental and practical significances which suggest a generalized way of making smart soft machine, collecting discrete metal fluids, as well as flexibly manipulating liquid metal objects including accompanying devices.

  19. Ultrasonic liquid level detector

    DOEpatents

    Kotz, Dennis M. (North Augusta, SC); Hinz, William R. (Augusta, GA)

    2010-09-28

    An ultrasonic liquid level detector for use within a shielded container, the detector being tubular in shape with a chamber at its lower end into which liquid from in the container may enter and exit, the chamber having an ultrasonic transmitter and receiver in its top wall and a reflector plate or target as its bottom wall whereby when liquid fills the chamber a complete medium is then present through which an ultrasonic wave may be transmitted and reflected from the target thus signaling that the liquid is at chamber level.

  20. Liquid Crystal Optofluidics

    SciTech Connect

    Vasdekis, Andreas E.; Cuennet, J. G.; Psaltis, D.

    2012-10-11

    By employing anisotropic fluids and namely liquid crystals, fluid flow becomes an additional degree of freedom in designing optofluidic devices. In this paper, we demonstrate optofluidic liquid crystal devices based on the direct flow of nematic liquid crystals in microfluidic channels. Contrary to previous reports, in the present embodiment we employ the effective phase delay acquired by light travelling through flowing liquid crystal, without analysing the polarisation state of the transmitted light. With this method, we demonstrate the variation in the diffraction pattern of an array of microfluidic channels acting as a grating. We also discuss our recent activities in integrating mechanical oscillators for on-chip peristaltic pumping.

  1. Liquid level detector

    DOEpatents

    Tokarz, Richard D. (West Richland, WA)

    1982-01-01

    A liquid level sensor having a pair of upright conductors spaced by an insulator defining a first high resistance path between the conductors. An electrically conductive path is interposed between the upright conductors at a discrete location at which liquid level is to be measured. It includes a liquid accessible gap of a dimension such that the electrical resistance across the conductor when the gap is filled with the liquid is detectably less than when the gap is emptied. The conductor might also be physically altered by temperature changes to serve also as an indicator of elevated temperature.

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

    SciTech Connect

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

    2015-06-21

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

  3. Heat Transfer from Optically Excited Gold Nanostructures into Water, Sugar, and Salt Solutions

    NASA Astrophysics Data System (ADS)

    Green, Andrew J.

    Nanotechnology has introduced a wide variety of new behaviors to study and understand. Metal nanostructures are of particular interest due to their ability to generate large amounts of heat when irradiated at the plasmon resonance. Furthermore, heat dissipation at the nanoscale becomes exceedingly more complicated with respect to bulk behavior. What are the credentials for a heat carrier to move across an interface? Is it important for both materials to have similar vibrational density of states? What changes if one material is a liquid? All of these questions have open ended answers, each of which hold potential for new technologies to be exploited once understood. This dissertation will discuss topics exploring the transfer of heat from an optically excited gold nanoparticle into a surrounding liquid. Gold nanostructures are created using conventional electron beam lithography with lift-off. The nanostructures are deposited onto a thin film thermal sensor composed of AlGaN:Er3+. Erbium(III) has two thermally coupled excited states that can be excited with a 532nm laser. The relative photoluminescence from these excited states are related by a Boltzmann factor and are thusly temperature dependent. A scanning optical microscope collects an image of Er3+ photoluminescence while simultaneously exciting the gold nanostructure. The nanostructure temperature is imaged which is directly related to the surrounding's heat dissipation properties. The first of two topics discuss the heat dissipation and phase change properties of water. A gold nanostructure is submersed under water and subsequently heated with a 532 nm laser. The water immediately surrounding the nanodot is can be superheated beyond the boiling point up to the spinodal decomposition temperature at 594 +/- 17 K. The spinodal decomposition has been confirmed with the observation of critical opalescence. We characterize the laser scattering that occurs in unison with spinodal decomposition due to an increased coherence length associated with the liquid-liquid transition. The second topic will measure the change in heat dissipation with respect to solute adhesion onto the nanoheater. A small amount of aqueous solute molecules (1 solute molecule in 550 water molecules) dramatically increases the heat dissipation from a nanoparticle into the surrounding liquid. This result is consistent with a thermal conductance that is limited by an interface interaction where minority aqueous components significantly alter the surface properties and heat transport through the interface. The increase in heat dissipation can be used to make an extremely sensitive molecular detector that can be scaled to give single molecule detection without amplification or utilizing fluorescence labels.

  4. Thermal excitations of warped membranes.

    PubMed

    Košmrlj, Andrej; Nelson, David R

    2014-02-01

    We explore thermal fluctuations of thin planar membranes with a frozen spatially varying background metric and a shear modulus. We focus on a special class of D-dimensional "warped membranes" embedded in a d-dimensional space with d ? D + 1 and a preferred height profile characterized by quenched random Gaussian variables {h(?)(q)}, ? = D + 1,...,d, in Fourier space with zero mean and a power-law variance h(?)(q(1))h(?)(q(2)) ? ?(?,?)?(q(1),-q(2))q(1)(-d(h)). The case D = 2, d = 3, with d(h) = 4 could be realized by flash-polymerizing lyotropic smectic liquid crystals. For D < max{4,d(h)} the elastic constants are nontrivially renormalized and become scale dependent. Via a self-consistent screening approximation we find that the renormalized bending rigidity increases for small wave vectors q as ?(R) ? q(-?(f)), while the in-hyperplane elastic constants decrease according to ?(R),?(R) ? q(+?(u)). The quenched background metric is relevant (irrelevant) for warped membranes characterized by exponent d(h) > 4-?(f)((F)) (d(h) < 4-?(f)((F))), where ?(f)((F)) is the scaling exponent for tethered surfaces with a flat background metric, and the scaling exponents are related through ?(u) + ?(f) = d(h) -D (?(u) + 2?(f) = 4-D). PMID:25353441

  5. Neutrons on a surface of liquid helium

    E-print Network

    P. D. Grigoriev; O. Zimmer; T. Ziman; A. D. Grigoriev

    2015-09-21

    We investigate the possibility of ultracold neutron (UCN) storage in quantum states defined by the combined potentials of the Earth's gravity and the neutron optical repulsion by a horizontal surface of liquid helium. We analyse the stability of the lowest quantum state, which is most susceptible to perturbations due to surface excitations, against scattering by helium atoms in the vapor and by excitations of the liquid, comprised of ripplons, phonons and surfons. This is an unusual scattering problem since the kinetic energy of the neutron parallel to the surface may be much greater than the binding energies perpendicular. The total scattering time constant of these UCNs at 0.7 K is found to exceed one hour, and rapidly increasing with decreasing temperature. Such low scattering rates should enable high-precision measurements of the scheme of discrete energy levels, thus providing improved access to short-range gravity. The system might also be useful for neutron beta-decay experiments. We also sketch new experimental concepts for level population and trapping of UCNs above a flat horizontal mirror.

  6. Neutrons on a surface of liquid helium

    E-print Network

    Grigoriev, P D; Ziman, T; Grigoriev, A D

    2015-01-01

    We investigate the possibility of ultracold neutron (UCN) storage in quantum states defined by the combined potentials of the Earth's gravity and the neutron optical repulsion by a horizontal surface of liquid helium. We analyse the stability of the lowest quantum state, which is most susceptible to perturbations due to surface excitations, against scattering by helium atoms in the vapor and by excitations of the liquid, comprised of ripplons, phonons and surfons. This is an unusual scattering problem since the kinetic energy of the neutron parallel to the surface may be much greater than the binding energies perpendicular. The total scattering time constant of these UCNs at 0.7 K is found to exceed one hour, and rapidly increasing with decreasing temperature. Such low scattering rates should enable high-precision measurements of the scheme of discrete energy levels, thus providing improved access to short-range gravity. The system might also be useful for neutron beta-decay experiments. We also sketch new ex...

  7. Method for beam steering compensation in an ultra-high power liquid laser

    DOEpatents

    Ault, Earl R. (Livermore, CA)

    2002-01-01

    Thermally induced distortion of the optical wavefront caused by heating of the laser media by waste heat from the excitation process and absorption of laser radiation creates optical phase errors. A system generates an error signal derived from the optical phase errors. The error signal is fed back to the power supplies driving semiconductor diodes that excite the lasing liquid thereby introducing an electrically controllable wedge into the optical cavity to correct the optical phase errors.

  8. (abstract) Production and Levitation of Free Drops of Liquid Helium

    NASA Technical Reports Server (NTRS)

    Paine, C. G.; Petrac, D.; Rhim, W. K.

    1995-01-01

    We are interested in the nucleation and behavior of quantized vorticies and surface excitations in free drops of superfluid helium. We have constructed an apparatus to maintain liquid helium drops isolated from any material container in the Earth's gravitational field, and have investigated two techniques for generating and introducing liquid drops into the region of confinement. The levitation apparatus utilizes the electrostatic force acting upon a charged liquid drop to counteract the gravitational force, with drop position stability provided by a static magnetic field acting upon the helium diamagnetic moment. Electrically neutral superfluid drops have been produced with a miniature thermomechanical pump; for a given configuration the liquid initial velocity has been varied up to several centimeters per second. Liquid drops carrying either net positive or negative charge are produced by an electrode which generates a flow of ionized liquid from the bulk liquid surface. Potentials of less than one thousand volts to several thousand volts are required. The mass flow is controlled by varying duration of the ionizing voltage pulse; drops as small as 30 micrometers diameter, charged to near the Rayleigh limit, have been observed.

  9. Dynamics of charge-transfer excited states relevant to photochemical energy conversion

    SciTech Connect

    Lim, E.C.

    1991-11-01

    The primary objective of the research program is to gain a fundamental understanding of the factors governing the efficiency of excited-state charge transfer CT interactions between two chromophores that are brought together in close proximity, either by a very short covalent linkage or by ground-state complex formation. CT and van der Walls (vdW), interactions in covalently bonded bichromophoric compounds in condensed phase, as well as those in vdW complexes in supersonic jets, are being investigated using laser-based techniques under a variety of experimental conditions. This progress report is divided into three parts, according to the class of molecular systems and the phase (liquid vs. gas) in which the excited-state interactions are probed. The first is concerned with the excited states of bridged diaryl compounds in the condensed phase. The second involves the excited states of vdW complexes in supersonic jets. Finally, the third, is concerned with the excited states of electron donor-acceptor (EDA) systems in both the condensed phase and supersonic jets. In each of these studies, we are concerned with the interchromophore interactions ranging from weak vdW forces to strong CT forces, and the factors determining whether the interaction forces are weak or strong in related molecules.

  10. Excited-State Proton Transfer in Resveratrol and Proposed Mechanism for Plant Resistance to Fungal Infection.

    PubMed

    Simkovitch, Ron; Huppert, Dan

    2015-09-01

    Steady-state and time-resolved fluorescence techniques were employed to study the photophysics and photochemistry of trans-resveratrol. trans-Resveratrol is found in large quantities in fungi-infected grapevine-leaf tissue and plays a direct role in the resistance to plant disease. We found that trans-resveratrol in liquid solution undergoes a trans-cis isomerization process in the excited state at a rate that depends partially on the solvent viscosity, as was found in previous studies on trans-stilbene. The hydroxyl groups of the phenol moieties in resveratrol are weak photoacids. In water and methanol solutions containing weak bases such as acetate, a proton is transferred to the base within the lifetime of the excited state. When resveratrol is adsorbed on cellulose (also a component of the plant's cell wall), the cis-trans process is slow and the lifetime of the excited state increases from several tens of picoseconds in ethanol to about 1.5 ns. Excited-state proton transfer occurs when resveratrol is adsorbed on cellulose and acetate ions are in close proximity to the phenol moieties. We propose that proton transfer from excited resveratrol to the fungus acid-sensing chemoreceptor is one of the plant's resistance mechanisms to fungal infection. PMID:26247232

  11. Scalability of mass transfer in liquid-liquid flow

    E-print Network

    Woitalka, A.

    We address liquid–liquid mass transfer between immiscible liquids using the system 1-butanol and water, with succinic acid as the mass transfer component. Using this system we evaluate the influence of two-phase flow ...

  12. Collisional excitation of interstellar sulfur dioxide

    NASA Technical Reports Server (NTRS)

    Palma, Amedeo

    1987-01-01

    State-to-state rotational excitation rates for the asymmetric top molecule SO2 in collisions with low-energy He atoms have been computed. The intermolecular forces were obtained from an electron gas model, and collision dynamics were treated with the finite-order sudden approximation. The total excitation rate is probably accurate to better than 50 percent; however, individual state-to-state rates may be in error by factors of 2 or 3, and some smaller rates may be accurate only to an order of magnitude. Present results are expected to reflect within the same level of accuracy rates for excitation by collisions with H2 molecules.

  13. Pulse Vector-Excitation Speech Encoder

    NASA Technical Reports Server (NTRS)

    Davidson, Grant; Gersho, Allen

    1989-01-01

    Proposed pulse vector-excitation speech encoder (PVXC) encodes analog speech signals into digital representation for transmission or storage at rates below 5 kilobits per second. Produces high quality of reconstructed speech, but with less computation than required by comparable speech-encoding systems. Has some characteristics of multipulse linear predictive coding (MPLPC) and of code-excited linear prediction (CELP). System uses mathematical model of vocal tract in conjunction with set of excitation vectors and perceptually-based error criterion to synthesize natural-sounding speech.

  14. Large-excitability asymptotics for scroll waves in three-dimensional excitable media Daniel Margerit* and Dwight Barkley

    E-print Network

    Barkley, Dwight

    Large-excitability asymptotics for scroll waves in three-dimensional excitable media Daniel-dimensional scroll waves are considered in a reaction-diffusion model of excitable media in the large excitability number s : 82.40.Ck, 47.54. r, 87.10. e I. INTRODUCTION Wave propagation in excitable media occur

  15. An Exact Chiral Spin Liquid with Non-Abelian Anyons

    SciTech Connect

    Yao, Hong

    2010-04-06

    We establish the existence of a chiral spin liquid (CSL) as the exact ground state of the Kitaev model on a decorated honeycomb lattice, which is obtained by replacing each site in the familiar honeycomb lattice with a triangle. The CSL state spontaneously breaks time reversal symmetry but preserves other symmetries. There are two topologically distinct CSLs separated by a quantum critical point. Interestingly, vortex excitations in the topologically nontrivial (Chern number {+-}1) CSL obey non-Abelian statistics.

  16. Liquid Chromatography in 1982.

    ERIC Educational Resources Information Center

    Freeman, David H.

    1982-01-01

    Reviews trends in liquid chromatography including apparatus, factors affecting efficient separation of a mixture (peak sharpness and speed), simplified problem-solving, adsorption, bonded phase chromatography, ion selectivity, and size exclusion. The current trend is to control chemical selectivity by the liquid phase. (Author/JN)

  17. Advanced proteomic liquid chromatography

    SciTech Connect

    Xie, Fang; Smith, Richard D.; Shen, Yufeng

    2012-10-26

    Liquid chromatography coupled with mass spectrometry is the predominant platform used to analyze proteomics samples consisting of large numbers of proteins and their proteolytic products (e.g., truncated polypeptides) and spanning a wide range of relative concentrations. This review provides an overview of advanced capillary liquid chromatography techniques and methodologies that greatly improve separation resolving power and proteomics analysis coverage, sensitivity, and throughput.

  18. Synthesis of ionic liquids

    DOEpatents

    Dai, Sheng [Knoxville, TN; Luo, Huimin [Knoxville, TN

    2008-09-09

    Ionic compounds which are liquids at room temperature are formed by the method of mixing a neutral organic liqand with the salt of a metal cation and its conjugate anion. The liquids are hydrophobic, conductive and stable and have uses as solvents and in electrochemical devices.

  19. Column Liquid Chromatography.

    ERIC Educational Resources Information Center

    Majors, Ronald E.; And Others

    1984-01-01

    Reviews literature covering developments of column liquid chromatography during 1982-83. Areas considered include: books and reviews; general theory; columns; instrumentation; detectors; automation and data handling; multidimensional chromatographic and column switching techniques; liquid-solid chromatography; normal bonded-phase, reversed-phase,…

  20. Guidance Document Cryogenic Liquids

    E-print Network

    have boiling points below -73°C (-100°F). The most common cryogenic liquids currently on campus conditions of temperature and pressure. But all have two very important properties in common. First, the liquids and their vapors are extremely cold. The risk of destructive freezing of tissues is always present

  1. Liquid heat capacity lasers

    DOEpatents

    Comaskey, Brian J. (Walnut Creek, CA); Scheibner, Karl F. (Tracy, CA); Ault, Earl R. (Livermore, CA)

    2007-05-01

    The heat capacity laser concept is extended to systems in which the heat capacity lasing media is a liquid. The laser active liquid is circulated from a reservoir (where the bulk of the media and hence waste heat resides) through a channel so configured for both optical pumping of the media for gain and for light amplification from the resulting gain.

  2. INEEL Liquid Effluent Inventory

    SciTech Connect

    Major, C.A.

    1997-06-01

    The INEEL contractors and their associated facilities are required to identify all liquid effluent discharges that may impact the environment at the INEEL. This liquid effluent information is then placed in the Liquid Effluent Inventory (LEI) database, which is maintained by the INEEL prime contractor. The purpose of the LEI is to identify and maintain a current listing of all liquid effluent discharge points and to identify which discharges are subject to federal, state, or local permitting or reporting requirements and DOE order requirements. Initial characterization, which represents most of the INEEL liquid effluents, has been performed, and additional characterization may be required in the future to meet regulations. LEI information is made available to persons responsible for or concerned with INEEL compliance with liquid effluent permitting or reporting requirements, such as the National Pollutant Discharge Elimination System, Wastewater Land Application, Storm Water Pollution Prevention, Spill Prevention Control and Countermeasures, and Industrial Wastewater Pretreatment. The State of Idaho Environmental Oversight and Monitoring Program also needs the information for tracking liquid effluent discharges at the INEEL. The information provides a baseline from which future liquid discharges can be identified, characterized, and regulated, if appropriate. The review covered new and removed buildings/structures, buildings/structures which most likely had new, relocated, or removed LEI discharge points, and at least 10% of the remaining discharge points.

  3. Precision liquid level sensor

    DOEpatents

    Field, Michael E. (Albuquerque, NM); Sullivan, William H. (Albuquerque, NM)

    1985-01-01

    A precision liquid level sensor utilizes a balanced R. F. bridge, each arm including an air dielectric line. Changes in liquid level along one air dielectric line imbalance the bridge and create a voltage which is directly measurable across the bridge.

  4. LIGHT NONAQUEOUS PHASE LIQUIDS

    EPA Science Inventory

    Nonaqueous phase liquids (NAPLS) are hydrocarbons that exist as a separate, immiscible phase when in contact with water and/or air. ifferences in the physical and chemical properties of water and NAPL result in the formation of a physical interface between the liquids which preve...

  5. Synthesis of ionic liquids

    SciTech Connect

    Dai, Sheng; Luo, Huimin

    2011-11-01

    Ionic compounds which are liquids at room temperature are formed by the method of mixing a neutral organic ligand with the salt of a metal cation and its conjugate anion. The liquids are hydrophobic, conductive and stable and have uses as solvents and in electrochemical devices.

  6. Precision liquid level sensor

    DOEpatents

    Field, M.E.; Sullivan, W.H.

    1985-01-29

    A precision liquid level sensor utilizes a balanced R. F. bridge, each arm including an air dielectric line. Changes in liquid level along one air dielectric line imbalance the bridge and create a voltage which is directly measurable across the bridge. 2 figs.

  7. Seismic excitation by space shuttles

    USGS Publications Warehouse

    Kanamori, H.; Mori, J.; Sturtevant, B.; Anderson, D.L.; Heaton, T.

    1992-01-01

    Shock waves generated by the space shuttles Columbia (August 13, 1989), Atlantis (April 11, 1991) and Discovery (September 18, 1991) on their return to Edwards Air Force Base, California, were recorded by TERRAscope (Caltech's broadband seismic network), the Caltech-U.S.G.S Southern California Seismic Network (SCSN), and the University of Southern California (USC) Los Angeles Basin Seismic Network. The spatial pattern of the arrival times exhibits hyperbolic shock fronts from which the path, velocity and altitude of the space shuttle could be determined. The shock wave was acoustically coupled to the ground, converted to a seismic wave, and recorded clearly at the broadband TERRAscope stations. The acoustic coupling occurred very differently depending on the conditions of the Earth's surface surrounding the station. For a seismic station located on hard bedrock, the shock wave (N wave) was clearly recorded with little distortion. Aside from the N wave, very little acoustic coupling of the shock wave energy to the ground occurred at these sites. The observed N wave record was used to estimate the overpressure of the shock wave accurately; a pressure change of 0.5 to 2.2 mbars was obtained. For a seismic station located close to the ocean or soft sedimentary basins, a significant amount of shock wave energy was transferred to the ground through acoustic coupling of the shock wave and the oceanic Rayleigh wave. A distinct topography such as a mountain range was found effective to couple the shock wave energy to the ground. Shock wave energy was also coupled to the ground very effectively through large man made structures such as high rise buildings and offshore oil drilling platforms. For the space shuttle Columbia, in particular, a distinct pulse having a period of about 2 to 3 seconds was observed, 12.5 s before the shock wave, with a broadband seismograph in Pasadena. This pulse was probably excited by the high rise buildings in downtown Los Angeles which were simultaneously hit by the space shuttle shock waves. The proximity of the natural periods of the high rise buildings and the modal periods of the Los Angeles basin enabled efficient energy transfer from shock wave to seismic wave. ?? 1992 Springer-Verlag.

  8. Resonant excitation of plasma wakefield

    NASA Astrophysics Data System (ADS)

    Fang, Yun

    Particle accelerators are the main tool for discovering new elementary particles. Plasma based accelerator (PWFA) has been proven a very attractive new acceleration technique due to the large acceleration gradient it has reached (>50GV/m), which is two to three orders higher than the conventional radio frequency accelerators. PWFA is essentially an energy transformer transferring the energy from the drive bunches to witness bunches. For a future more compact and more affordable linear electron/positron collider, such an accelerator will require drive bunches with small longitudinal size (on the order of 100 um) and multi-kilojules of energy to access the new physics at the energy frontier. However, present relativistic electron bunch drivers carry less than 100Joules, thereby limiting the energy gain by the accelerated bunch to less than 100Joules. Proton bunches produced at CERN have been proven as potential drivers for PWFA due to the many tens of kilojules energy they carry (1e11 particles, 3.5-7TeV per particle). However, the CERN proton bunches are too long (approximately 12cm) to drive the wakefield efficiently. It has been proposed that a long particle bunch (protons, electrons, positrons, ... ) traveling in dense plasmas is subject to self-modulation instability (SMI), which transversely modulates a long bunch into multiple short bunches (on the scale of plasma wavelength) and therefore results in high acceleration amplitudes through resonant excitation. In this thesis, we demonstrate the first experimental evidence for the seeding of SMI with an electron bunch. We also use numerical simulations to study the SMI development with a higher-charge electron bunch and propose a possible experiment to demonstrate the transverse modulation directly in experiments. Moreover, we investigate with simulations the effect of transverse plasma radius on the SMI development, which is an important factor to consider when designing plasmas for future SMI and SMI-based experiments. Besides efficient drivers such as high-energy proton bunches, the PWFA also requires high transformer ratio (an indication of energy transfer efficiency) so that the witness bunch can gain energy efficiently from the drive bunch. In this thesis, we explore the possibility of reaching high transformer ratio in the weakly nonlinear PWFA regime so that the witness bunch particles can gain many times the energy of the drive bunch particles in a single acceleration stage.

  9. Excitation nonlinearities in emission reabsorption laser-induced fluorescence techniques

    E-print Network

    Hidrovo, Carlos H.

    Excitation nonlinearities in emission reabsorption laser-induced fluorescence techniques Carlos H intensity with excitation intensity on emission reabsorption laser-induced fluorescence ERLIF are investigated. Excitation nonlinearities arise mainly as a consequence of the depletion of the ground

  10. Liquid metal enabled pump

    PubMed Central

    Tang, Shi-Yang; Khoshmanesh, Khashayar; Sivan, Vijay; Petersen, Phred; O’Mullane, Anthony P.; Abbott, Derek; Mitchell, Arnan; Kalantar-zadeh, Kourosh

    2014-01-01

    Small-scale pumps will be the heartbeat of many future micro/nanoscale platforms. However, the integration of small-scale pumps is presently hampered by limited flow rate with respect to the input power, and their rather complicated fabrication processes. These issues arise as many conventional pumping effects require intricate moving elements. Here, we demonstrate a system that we call the liquid metal enabled pump, for driving a range of liquids without mechanical moving parts, upon the application of modest electric field. This pump incorporates a droplet of liquid metal, which induces liquid flow at high flow rates, yet with exceptionally low power consumption by electrowetting/deelectrowetting at the metal surface. We present theory explaining this pumping mechanism and show that the operation is fundamentally different from other existing pumps. The presented liquid metal enabled pump is both efficient and simple, and thus has the potential to fundamentally advance the field of microfluidics. PMID:24550485

  11. Students Excited by Stellar Discovery

    NASA Astrophysics Data System (ADS)

    2011-02-01

    In the constellation of Ophiuchus, above the disk of our Milky Way Galaxy, there lurks a stellar corpse spinning 30 times per second -- an exotic star known as a radio pulsar. This object was unknown until it was discovered last week by three high school students. These students are part of the Pulsar Search Collaboratory (PSC) project, run by the National Radio Astronomy Observatory (NRAO) in Green Bank, WV, and West Virginia University (WVU). The pulsar, which may be a rare kind of neutron star called a recycled pulsar, was discovered independently by Virginia students Alexander Snider and Casey Thompson, on January 20, and a day later by Kentucky student Hannah Mabry. "Every day, I told myself, 'I have to find a pulsar. I better find a pulsar before this class ends,'" said Mabry. When she actually made the discovery, she could barely contain her excitement. "I started screaming and jumping up and down." Thompson was similarly expressive. "After three years of searching, I hadn't found a single thing," he said, "but when I did, I threw my hands up in the air and said, 'Yes!'." Snider said, "It actually feels really neat to be the first person to ever see something like that. It's an uplifting feeling." As part of the PSC, the students analyze real data from NRAO's Robert C. Byrd Green Bank Telescope (GBT) to find pulsars. The students' teachers -- Debra Edwards of Sherando High School, Leah Lorton of James River High School, and Jennifer Carter of Rowan County Senior High School -- all introduced the PSC in their classes, and interested students formed teams to continue the work. Even before the discovery, Mabry simply enjoyed the search. "It just feels like you're actually doing something," she said. "It's a good feeling." Once the pulsar candidate was reported to NRAO, Project Director Rachel Rosen took a look and agreed with the young scientists. A followup observing session was scheduled on the GBT. Snider and Mabry traveled to West Virginia to assist in the follow-up observations, and Thompson joined online. "Observing with the students is very exciting. It gives the students a chance to learn about radio telescopes and pulsar observing in a very hands-on way, and it is extra fun when we find a pulsar," said Rosen. Snider, on the other hand, said, "I got very, very nervous. I expected when I went there that I would just be watching other people do things, and then I actually go to sit down at the controls. I definitely didn't want to mess something up." Everything went well, and the observations confirmed that the students had found an exotic pulsar. "I learned more in the two hours in the control room than I would have in school the whole day," Mabry said. Pulsars are spinning neutron stars that sling lighthouse beams of radio waves or light around as they spin. A neutron star is what is left after a massive star explodes at the end of its normal life. With no nuclear fuel left to produce energy to offset the stellar remnant's weight, its material is compressed to extreme densities. The pressure squeezes together most of its protons and electrons to form neutrons; hence, the name neutron star. One tablespoon of material from a pulsar would weigh 10 million tons -- as much as a supertanker. The object that the students discovered is in a special class of pulsar that spins very fast - in this case, about 30 times per second, comparable to the speed of a kitchen blender. "The big question we need to answer first is whether this is a young pulsar or a recycled pulsar," said Maura McLaughlin, an astronomer at WVU. "A pulsar spinning that fast is very interesting as it could be newly born or it could be a very old, recycled pulsar." A recycled pulsar is one that was once in a binary system. Material from the companion star is deposited onto the pulsar, causing it to speed up, or be recycled. Mystery remains, however, about whether this pulsar has ever had a companion star. If it did, "it may be t

  12. How to excite a rogue wave

    SciTech Connect

    Akhmediev, N.; Ankiewicz, A.; Soto-Crespo, J. M.

    2009-10-15

    We propose initial conditions that could facilitate the excitation of rogue waves. Understanding the initial conditions that foster rogue waves could be useful both in attempts to avoid them by seafarers and in generating highly energetic pulses in optical fibers.

  13. "Safe" Coulomb Excitation of 30Mg

    E-print Network

    O. Niedermaier; H. Scheit; V. Bildstein; H. Boie; J. Fitting; R. von Hahn; F. K"ock; M. Lauer; U. K. Pal; H. Podlech; R. Repnow; D. Schwalm

    2004-12-17

    We report on the first radioactive beam experiment performed at the recently commissioned REX-ISOLDE facility at CERN in conjunction with the highly efficient gamma spectrometer MINIBALL. Using 30Mg ions accelerated to an energy of 2.25 MeV/u together with a thin nat-Ni target, Coulomb excitation of the first excited 2+ states of the projectile and target nuclei well below the Coulomb barrier was observed. From the measured relative de-excitation gamma ray yields the B(E2; 0+ -> 2+) value of 30Mg was determined to be 241(31) e2fm4. Our result is lower than values obtained at projectile fragmentation facilities using the intermediate-energy Coulomb excitation method, and confirms the theoretical conjecture that the neutron-rich magnesium isotope 30Mg lies still outside the ``island of inversion''.

  14. Stimulated excitation electron microscopy and spectroscopy.

    PubMed

    Howie, A

    2015-04-01

    Recent advances in instrumentation for electron optics and spectroscopy have prompted exploration of ultra-low excitations such as phonons, bond vibrations and Johnson noise. These can be excited not just with fast electrons but also thermally or by other external sources of radiation. The near-field theory of electron energy loss and gain provides a convenient platform for analysing these processes. Possibilities for selected phonon mapping and imaging are discussed. Effects should certainly be observable in atomic resolution structure imaging but diffraction contrast imaging could perhaps be more informative. Additional exciting prospects to be explored include the transition from phonon excitation to single atom recoil and the boosting of energy loss and gain signals with tuned laser illumination. PMID:25312246

  15. Dissociative Excitation of Thymine by Electron Impact

    NASA Astrophysics Data System (ADS)

    McConkey, William; Tiessen, Collin; Hein, Jeffrey; Trocchi, Joshuah; Kedzierski, Wladek

    2014-05-01

    A crossed electron-gas beam system coupled to a VUV spectrometer has been used to investigate the dissociation of thymine (C5H6N2O2) into excited atomic fragments in the electron-impact energy range from threshold to 375 eV. A special stainless steel oven is used to vaporize the thymine and form it into a beam where it is intersected by a magnetically collimated electron beam, typical current 50 ?A. The main features in the spectrum are the H Lyman series lines. The probability of extracting excited C or N atoms from the ring is shown to be very small. In addition to spectral data, excitation probability curves as a function of electron energy will be presented for the main emission features. Possible dissociation channels and excitation mechanisms in the parent molecule will be discussed. The authors thank NSERC (Canada) for financial support.

  16. Ultrafast optical excitation of magnetic skyrmions.

    PubMed

    Ogawa, N; Seki, S; Tokura, Y

    2015-01-01

    Magnetic skyrmions in an insulating chiral magnet Cu2OSeO3 were studied by all-optical spin wave spectroscopy. The spins in the conical and skyrmion phases were excited by the impulsive magnetic field from the inverse-Faraday effect, and resultant spin dynamics were detected by using time-resolved magneto-optics. Clear dispersions of the helimagnon were observed, which is accompanied by a distinct transition into the skyrmion phase, by sweeping temperature and magnetic field. In addition to the collective excitations of skyrmions, i.e., rotation and breathing modes, several spin precession modes were identified, which would be specific to optical excitation. The ultrafast, nonthermal, and local excitation of the spin systems by photons would lead to the efficient manipulation of nano-magnetic structures. PMID:25897634

  17. The DSS-14 C-band exciter

    NASA Technical Reports Server (NTRS)

    Rowan, D. R.

    1989-01-01

    The development and implementation of a C-band exciter for use with the Block IV Receiver-Exciter Subsystem at Deep Space Station 14 (DSS-14) has been completed. The exciter supplements the standard capabilities of the Block IV system by providing a drive signal for the C-band transmitter while generating coherent translation frequencies for C-band (5-GHz) to S-band (2.2- to 2.3-GHz) Doppler extraction, C-band to L-band (1.6-GHz) zero delay measurements, and a level calibrated L-band test signal. Exciter functions are described, and a general explanation and description of the C-band uplink controller is presented.

  18. Fear, excitement, and financial risk-taking.

    PubMed

    Lee, Chan Jean; Andrade, Eduardo B

    2015-01-01

    Can fear trigger risk-taking? In this paper, we assess whether fear can be reinterpreted as a state of excitement as a result of contextual cues and promote, rather than discourage, risk-taking. In a laboratory experiment, the participants' emotional states were induced (fear vs. control), followed by a purportedly unrelated financial task. The task was framed as either a stock market investment or an exciting casino game. Our results showed that incidental fear (vs. control) induced risk-averse behaviour when the task was framed as a stock investment decision. However, fear encouraged risk-taking when the very same task was framed as an exciting casino game. The impact of fear on risk-taking was partially mediated by the excitement felt during the financial task. PMID:24661027

  19. Mode Selective Excitation Using Coherent Control Spectroscopy

    SciTech Connect

    Singh, Ajay K.; Konradi, Jakow; Materny, Arnulf; Sarkar, Sisir K.

    2008-11-14

    Femtosecond time-resolved coherent anti-Stokes Raman scattering (fs-CARS) gives access to ultrafast molecular dynamics. However, femtosecond laser pulses are spectrally broad and therefore coherently excite several molecular modes. While the temporal resolution is high, usually no mode-selective excitation is possible. This paper demonstrates the feasibility of selectively exciting specific molecular vibrations in solution phase with shaped fs laser excitation using a feedback-controlled optimization technique guided by an evolutionary algorithm. This approach is also used to obtain molecule-specific CARS spectra from a mixture of different substances. The optimized phase structures of the fs pulses are characterized to get insight into the control process. Possible applications of the spectrum control are discussed.

  20. Acoustics of Excited Jets: A Historical Perspective

    NASA Technical Reports Server (NTRS)

    Brown, Cliffard A.

    2005-01-01

    The idea that a jet may be excited by external forcing is not new. The first published demonstration of a jet responding to external pressure waves occurred in the mid-1800's. It was not, however, until the 1950's, with the advent of commercial jet aircraft, that interest in the subject greatly increased. Researchers first used excited jets to study the structure of the jet and attempt to determine the nature of the noise sources. The jet actuators of the time limited the range (Reynolds and Mach numbers) of jets that could be excited. As the actuators improved, more realistic jets could be studied. This has led to a better understanding of how jet excitation may be used not only as a research tool to understand the flow properties and noise generation process, but also as a method to control jet noise.

  1. Nonlinear excited waves on the interventricular septum

    NASA Astrophysics Data System (ADS)

    Bekki, Naoaki; Harada, Yoshifumi; Kanai, Hiroshi

    2012-11-01

    Using a novel ultrasonic noninvasive imaging method, we observe some phase singularities in propagating excited waves on a human cardiac interventricular septum (IVS) for a healthy young male. We present a possible physical model explaining one-dimensional dynamics of phase singularities in nonlinearly excited waves on the IVS. We show that at least one of the observed phase singularities in the excited waves on the IVS can be explained by the Bekki-Nozaki hole solution of the complex Ginzburg-Landau equation without any adjustable parameters. We conclude that the complex Ginzburg-Landau equation is such a suitable model for one-dimensional dynamics of cardiac phase singularities in nonlinearly excited waves on the IVS.

  2. Mode Selective Excitation Using Coherent Control Spectroscopy

    NASA Astrophysics Data System (ADS)

    Singh, Ajay K.; Konradi, Jakow; Sarkar, Sisir K.; Materny, Arnulf

    2008-11-01

    Femtosecond time-resolved coherent anti-Stokes Raman scattering (fs-CARS) gives access to ultrafast molecular dynamics. However, femtosecond laser pulses are spectrally broad and therefore coherently excite several molecular modes. While the temporal resolution is high, usually no mode-selective excitation is possible. This paper demonstrates the feasibility of selectively exciting specific molecular vibrations in solution phase with shaped fs laser excitation using a feedback-controlled optimization technique guided by an evolutionary algorithm. This approach is also used to obtain molecule-specific CARS spectra from a mixture of different substances. The optimized phase structures of the fs pulses are characterized to get insight into the control process. Possible applications of the spectrum control are discussed.

  3. Collective Ion Dynamics in Liquid Zinc: Evidence for Complex Dynamics in a Non-Free-Electron Liquid Metal

    NASA Astrophysics Data System (ADS)

    Zanatta, M.; Sacchetti, F.; Guarini, E.; Orecchini, A.; Paciaroni, A.; Sani, L.; Petrillo, C.

    2015-05-01

    A detailed inelastic neutron scattering investigation of the THz dynamics of liquid zinc is presented. The observed Q dependence clearly reveals the existence of a complex dynamics made up of two distinct excitations. The highest energy mode is the prolongation of the longitudinal acoustic density fluctuations whereas the comparison with the phonon dynamics of crystalline hcp zinc suggests a transverse acousticlike nature for the second one. This mode seems related to peculiar anisotropic interactions, possibly connected to the behavior of the crystalline phase.

  4. Comparison of vapor formation of water at the solid/water interface to colloidal solutions using optically excited gold nanostructures.

    PubMed

    Baral, Susil; Green, Andrew J; Livshits, Maksim Y; Govorov, Alexander O; Richardson, Hugh H

    2014-02-25

    The phase transformation properties of liquid water to vapor is characterized by optical excitation of the lithographically fabricated single gold nanowrenches and contrasted to the phase transformation properties of gold nanoparticles located and optically excited in a bulk solution system [two and three dimensions]. The 532 nm continuous wave excitation of a single gold nanowrench results in superheating of the water to the spinodal decomposition temperature of 580 ± 20 K with bubble formation below the spinodal decomposition temperature being a rare event. Between the spinodal decomposition temperature and the boiling point liquid water is trapped into a metastable state because a barrier to vapor nucleation exists that must be overcome before the thermodynamically stable state is realized. The phase transformation for an optically heated single gold nanowrench is different from the phase transformation of optically excited colloidal gold nanoparticles solution where collective heating effects dominates and leads to the boiling of the solution exactly at the boiling point. In the solution case, the optically excited ensemble of nanoparticles collectively raises the ambient temperature of water to the boiling point where liquid is converted into vapor. The striking difference in the boiling properties of the single gold nanowrench and the nanoparticle solution system can be explained in terms of the vapor-nucleation mechanism, the volume of the overheated liquid, and the collective heating effect. The interpretation of the observed regimes of heating and vaporization is consistent with our theoretical modeling. In particular, we explain with our theory why the boiling with the collective heating in a solution requires 3 orders of magnitude less intensity compared to the case of optically driven single nanowrench. PMID:24476426

  5. Evolution of locally excited avalanches in semiconductors

    E-print Network

    Z. L. Yuan; J. F. Dynes; A. W. Sharpe; A. J. Shields

    2010-05-25

    We show that semiconductor avalanche photodiodes can exhibit diminutive amplification noise during the early evolution of avalanches. The noise is so low that the number of locally excited charges that seed each avalanche can be resolved. These findings constitute an important first step towards realization of a solid-state noiseless amplifier. Moreover, we believe that the experimental setup used, \\textit{i.e.}, time-resolving locally excited avalanches, will become a useful tool for optimizing the number resolution.

  6. Table-top setup for investigating the scintillation properties of liquid argon

    E-print Network

    Heindl, T; Fedenev, A; Hofmann, M; Krücken, R; Oberauer, L; Potzel, W; Wieser, J; Ulrich, A

    2015-01-01

    The spectral and temporal light emission properties of liquid argon have been studied in the context of its use in large liquid rare-gas detectors for detecting Dark Matter particles in astronomy. A table-top setup has been developed. Continuous and pulsed low energy electron beam excitation is used to stimulate light emission. A spectral range from 110 to 1000 nm in wavelength is covered by the detection system with a time resolution on the order of 1 ns.

  7. Vacuum ultraviolet light production by nuclear irradiation of liquid and gaseous xenon

    NASA Technical Reports Server (NTRS)

    Baldwin, G. C.

    1981-01-01

    Recent Los Alamos investigations suggest that a liquefied noble element may be the long-sought medium for a nuclear-excited laser or flashlamp. Research is needed to confirm this finding and to provide a basis for design and application studies. Quantitative and qualitative information are needed on the nature and behavior of the excited species, the effects of impurities and additives in the liquid phase under nuclear excitation, and the existence and magnitudes of nonlinear effects. Questions that need to be addressed and the most appropriate types of facilities for this task are identified.

  8. Noncavitating Pump For Liquid Helium

    NASA Technical Reports Server (NTRS)

    Hasenbein, Robert; Izenson, Michael; Swift, Walter; Sixsmith, Herbert

    1996-01-01

    Immersion pump features high efficiency in cryogenic service. Simple and reliable centrifugal pump transfers liquid helium with mass-transfer efficiency of 99 percent. Liquid helium drawn into pump by helical inducer, which pressurizes helium slightly to prevent cavitation when liquid enters impeller. Impeller then pressurizes liquid. Purpose of pump to transfer liquid helium from supply to receiver vessel, or to provide liquid helium flow for testing and experimentation.

  9. Recombination and collisionally excited Balmer lines

    NASA Astrophysics Data System (ADS)

    Raga, A. C.; Castellanos-Ramírez, A.; Esquivel, A.; Rodríguez-González, A.; Velázquez, P. F.

    2015-10-01

    We present a model for the statistical equilibrium of the levels of H, considering recombinations to excited levels, collisional excitations up from the ground state and spontaneous radiative transitions. This problem has a simple "cascade matrix" solution, describing a cascade of downwards spontaneous transitions fed by both recombinations and collisional excitations. The resulting predicted Balmer line ratios show a transition between a low temperature and a high temperature regime (dominated by recombinations and by collisional excitations, respectively), both with only a weak line ratio vs. temperature dependence. This clear characteristic allows a direct observational identification of regions in which the Balmer lines are either recombination or collisionally excited transitions. We find that for a gas in coronal ionization equilibrium the Halpha and Hbeta lines are collisionally excited for all temperatures. In order to have recombination Halpha and Hbeta it is necessary to have higher ionization fractions of H than the ones obtained from coronal equilibrium (e.g., such as the ones found in a photoionized gas).

  10. Excitation Efficiency of a Cold Rydberg Gas

    NASA Astrophysics Data System (ADS)

    Stanojevic, J.; Farooqi, S. M.; Tong, D.; Krishnan, S.; Zhang, Y. P.; Estrin, A. S.; Côté, R.; Calsamiglia, John; Eyler, E. E.; Gould, P. L.

    2003-05-01

    We have investigated the excitation efficiency of a cold gas to highly-excited Rydberg states. We start with ^85Rb atoms at a density of ˜10^11 cm-3 in a magneto-optical trap, and illuminate them with a narrow-band UV pulse (? = 297 nm, ? = 8 ns), resonant with a single-photon transition from the 5s ground state to 90p. The number of Rydberg atoms thereby excited is determined by field ionization and electron detection. For a UV intensity of 1500 MW/cm^2, roughly 130 times the single-atom saturation intensity, we find a surprisingly small excitation efficiency of ˜4 %. Free electrons produced during or within ˜25 ns of the laser pulse constitute a small fraction of the observed signal. This reduced excitation efficiency may be related to the dipole blockade mechanism ( M.D. Lukin, et al., Phys. Rev. Lett. 87), 037901 (2001). where strong Rydberg-Rydberg interactions inhibit neighboring atoms from being excited.

  11. Liquid metals. Concepts and theory.

    NASA Astrophysics Data System (ADS)

    March, N. H.

    A research level comprehensive introduction to the theory and concepts of liquid metals. The book begins with a survey of the basic experimental facts and reviews the concepts needed to understand the properties of liquid metals. The quantitative theory of liquid pair correlation functions, effective ion-ion interactions, thermodynamic properties, and electronic and atomic transport is then developed. The book goes on to discuss inelastic neutron scattering from bulk liquid metals, a discussion of critical behavior, magnetism, and present understanding of the liquid metal surface, binary liquid metal alloys, the two component theory of pure liquid metals, shock wave studies, liquid hydrogen plasmas, and the constitution of giant planets.

  12. Ultrafast conversions between hydrogen bonded structures in liquid water observed by femtosecond x-ray spectroscopy

    SciTech Connect

    Wen, Haidan; Huse, Nils; Schoenlein, Robert W.; Lindenberg, Aaron M.

    2010-05-01

    We present the first femtosecond soft x-ray spectroscopy in liquids, enabling the observation of changes in hydrogen bond structures in water via core-hole excitation. The oxygen K-edge of vibrationally excited water is probed with femtosecond soft x-ray pulses, exploiting the relation between different water structures and distinct x-ray spectral features. After excitation of the intramolecular OH stretching vibration, characteristic x-ray absorption changes monitor the conversion of strongly hydrogen-bonded water structures to more disordered structures with weaker hydrogen-bonding described by a single subpicosecond time constant. The latter describes the thermalization time of vibrational excitations and defines the characteristic maximum rate with which nonequilibrium populations of more strongly hydrogen-bonded water structures convert to less-bonded ones. On short time scales, the relaxation of vibrational excitations leads to a transient high-pressure state and a transient absorption spectrum different from that of statically heated water.

  13. Mirrorless dye doped ionic liquid lasers.

    PubMed

    Barna, Valentin; De Cola, Luisa

    2015-05-01

    The study of electromagnetic waves propagation in periodically structured dielectrics and the linear and nonlinear optical phenomena in disordered systems doped with gain media represent one of the most challenging and exciting scientific areas of the past decade. Lasing and Random Lasers (RL) are fascinating examples of topics that synergize multiple scattering of light and optical amplification and lately have been the subject of intense theoretical and experimental studies. In this manuscript we demonstrate laser action in a new category of materials, namely dye doped ionic liquids. Ionic liquids prove to be perfect candidates for building, as shown, a series of exotic boundaryless or confined compact laser systems. Lasing is presented in standard wedge cells, freely suspended ionic liquid films and droplets. The optical emission properties are investigated in terms of spectral analysis, below and above lasing energy threshold behavior, emission efficiency, far field spatial laser modes intensity profiling, temporal emission behavior etc. As demonstrated, these materials can be employed as optimal near future replacements of conventional flammable solvents in already available dye laser instruments. PMID:25969283

  14. Liquid sampling system

    DOEpatents

    Larson, Loren L. (Idaho Falls, ID)

    1987-01-01

    A conduit extends from a reservoir through a sampling station and back to the reservoir in a closed loop. A jet ejector in the conduit establishes suction for withdrawing liquid from the reservoir. The conduit has a self-healing septum therein upstream of the jet ejector for receiving one end of a double-ended cannula, the other end of which is received in a serum bottle for sample collection. Gas is introduced into the conduit at a gas bleed between the sample collection bottle and the reservoir. The jet ejector evacuates gas from the conduit and the bottle and aspirates a column of liquid from the reservoir at a high rate. When the withdrawn liquid reaches the jet ejector the rate of flow therethrough reduces substantially and the gas bleed increases the pressure in the conduit for driving liquid into the sample bottle, the gas bleed forming a column of gas behind the withdrawn liquid column and interrupting the withdrawal of liquid from the reservoir. In the case of hazardous and toxic liquids, the sample bottle and the jet ejector may be isolated from the reservoir and may be further isolated from a control station containing remote manipulation means for the sample bottle and control valves for the jet ejector and gas bleed.

  15. Liquid sampling system

    DOEpatents

    Larson, L.L.

    1984-09-17

    A conduit extends from a reservoir through a sampling station and back to the reservoir in a closed loop. A jet ejector in the conduit establishes suction for withdrawing liquid from the reservoir. The conduit has a self-healing septum therein upstream of the jet ejector for receiving one end of a double-ended cannula, the other end of which is received in a serum bottle for sample collection. Gas is introduced into the conduit at a gas bleed between the sample collection bottle and the reservoir. The jet ejector evacuates gas from the conduit and the bottle and aspirates a column of liquid from the reservoir at a high rate. When the withdrawn liquid reaches the jet ejector the rate of flow therethrough reduces substantially and the gas bleed increases the pressure in the conduit for driving liquid into the sample bottle, the gas bleed forming a column of gas behind the withdrawn liquid column and interrupting the withdrawal of liquid from the reservoir. In the case of hazardous and toxic liquids, the sample bottle and the jet ejector may be isolated from the reservoir and may be further isolated from a control station containing remote manipulation means for the sample bottle and control valves for the jet ejector and gas bleed. 5 figs.

  16. Tailoring dye-sensitized upconversion nanoparticle excitation bands towards excitation wavelength selective imaging.

    PubMed

    Wu, Xiang; Lee, Hyungseok; Bilsel, Osman; Zhang, Yuanwei; Li, Zhanjun; Chen, Teresa; Liu, Yi; Duan, Chunying; Shen, Jie; Punjabi, Amol; Han, Gang

    2015-11-28

    One of the key roadblocks in UCNP development is its extremely limited choices of excitation wavelengths. We report a generic design to program UCNPs to possess highly tunable dye characteristic excitation bands. Using such distinctive properties, we were able to develop a new excitation wavelength selective security imaging. This work unleashed the greater freedom of the excitation wavelengths of the upconversion nanoparticles and we believe it is a game-changer in the field and this method will enable numerous applications that are currently limited by existing UCNPs. PMID:26499208

  17. Tailoring Dye-sensitized Upconversion Nanoparticles Excitation Bands towards Excitation Wavelength Selective Imaging

    PubMed Central

    Wu, Xiang; Lee, Hyungseok; Bilsel, Osman; Zhang, Yuanwei; Li, Zhanjun; Chen, Teresa; Liu, Yi; Duan, Chunying; Shen, Jie; Punjabi, Amol; Han, Gang

    2015-01-01

    One of key roadblocks in UCNP development is its extremely limited choices of excitation wavelengths. We report a generic design to program UCNPs to possess highly tunable dye characteristic excitation bands. Using such distinctive properties, we were able to develop a new excitation wavelength selective security imaging. This work unleashed the greater freedom of the excitation wavelengths of the upconversion nanoparticles and we believe it is a game-changer in the field and this method will enable numerous applications that are currently limited by existing UCNPs. PMID:26499208

  18. Liquid metal drop ejection

    NASA Technical Reports Server (NTRS)

    Khuri-Yakub, B. T.

    1993-01-01

    The aim of this project was to demonstrate the possibility of ejecting liquid metals using drop on demand printing technology. The plan was to make transducers for operation in the 100 MHz frequency range and to use these transducers to demonstrate the ability to eject drops of liquid metals such as gallium. Two transducers were made by indium bonding piezoelectric lithium niobate to quartz buffer rods. The lithium niobate plates were thinned by mechanical polishing to a thickness of 37 microns for operation at 100 MHz. Hemispherical lenses were polished in the opposite ends of the buffer rods. The lenses, which focus the sound waves in the liquid metal, had an F-number equals 1. A mechanical housing was made to hold the transducers and to allow precise control over the liquid level above the lens. We started by demonstrating the ability to eject drops of water on demand. The drops of water had a diameter of 15 microns which corresponds to the wavelength of the sound wave in the water. A videotape of this ejection was made. We then used a mixture of Gallium and Indium (used to lower the melting temperature of the Gallium) to demonstrate the ejection of liquid metal drops. This proved to be difficult because of the oxide skin which forms on the surface of the liquid. In some instances, we were able to eject metal drops, however, this was not consistent and reproducible. An experiment was set up at NASA-Lewis to stabilize the process of drop on demand liquid metal ejection. The object was to place the transducer and liquid metal in a vacuum station so that no oxide would form on the surface. We were successful in demonstrating that liquid metals could be ejected on demand and that this technology could be used for making sheet metal in space.

  19. Liquid metal electric pump

    DOEpatents

    Abbin, J.P.; Andraka, C.E.; Lukens, L.L.; Moreno, J.B.

    1992-01-14

    An electrical pump for pumping liquid metals to high pressures in high temperature environments without the use of magnets or moving mechanical parts. The pump employs a non-porous solid electrolyte membrane, typically ceramic, specific to the liquid metal to be pumped. A DC voltage is applied across the thickness of the membrane causing ions to form and enter the membrane on the electrically positive surface, with the ions being neutralized on the opposite surface. This action provides pumping of the liquid metal from one side of the non-porous solid electrolyte membrane to the other. 3 figs.

  20. Liquid metal electric pump

    DOEpatents

    Abbin, Joseph P. (Albuquerque, NM); Andraka, Charles E. (Albuquerque, NM); Lukens, Laurance L. (Albuquerque, NM); Moreno, James B. (Albuquerque, NM)

    1992-01-01

    An electrical pump for pumping liquid metals to high pressures in high temperature environments without the use of magnets or moving mechanical parts. The pump employs a non-porous solid electrolyte membrane, typically ceramic, specific to the liquid metal to be pumped. A DC voltage is applied across the thickness of the membrane causing ions to form and enter the membrane on the electrically positive surface, with the ions being neutralized on the opposite surface. This action provides pumping of the liquid metal from one side of the non-porous solid electrolyte membrane to the other.

  1. Electrically Deformable Liquid Marbles

    E-print Network

    Edward Bormashenko; Roman Pogreb; Tamir Stein; Gene Whyman; Marcelo Schiffer; Doron Aurbach

    2011-02-17

    Liquid marbles, which are droplets coated with a hydrophobic powder, were exposed to a uniform electric field. It was established that a threshold value of the electric field, 15 cgse, should be surmounted for deformation of liquid marbles. The shape of the marbles was described as a prolate spheroid. The semi-quantitative theory describing deformation of liquid marbles in a uniform electric field is presented. The scaling law relating the radius of the contact area of the marble to the applied electric field shows a satisfactory agreement with the experimental data.

  2. Instability analysis of resonant standing waves in a parametrically excited boxed basin

    NASA Astrophysics Data System (ADS)

    Sirwah, Magdy A.

    2009-06-01

    Two-mode parametric excited interfacial waves of incompressible immiscible liquids in an infinite boxed basin subjected to a vertical excitation are studied. The method of multiple time scales is used to obtain uniform solutions of the second-order system as well as the third-order one, which in turn leads to the solvability conditions of the two orders including the cubic interaction terms. The different cases of resonance that arise among the natural frequencies together with the frequency of the vertical vibration of the box are demonstrated theoretically and numerical computations of one of these cases (the two-to-one internal resonance and the principal parametric resonance) have been performed in detail in order to investigate the behavior of the resonant waves, especially the qualitative one. The autonomous system of four first-order differential equations for the modulation of the amplitudes and phases of the resonant waves is derived. Some numerical applications are achieved to show the stability criteria of the excited liquids inside the considered basin.

  3. Surface plasmon resonance on the surface: metal - liquid crystal layer

    NASA Astrophysics Data System (ADS)

    Zhelyazkova, K.; Petrov, M.; Katranchev, B.; Dyankov, G.

    2014-12-01

    Surface plasmon resonance (SPR) is widely used in different types of optical detection schemes and for light manipulation at sub-wavelength scale. Usually Kretschmann configuration is used for effective SPR excitation. There are a lot of experimental and theoretical investigations about the influence of the dielectric, adjacent to the metal, on SPR. However, till now the influence on liquid crystal layer, adjacent to the metal, is not considered to our best knowledge. The purpose of the present paper is to cover this gap. We simulate the influence of thin layer of liquid crystal, adjacent to the metal, on the SPR characteristics. For this purpose Maxwell equations are numerically solved for layer structure: prism/gold/liquid crystal/air. The light reflection spectra are calculated for chiral structure of ferroelectric smectic C (SmC*) liquid crystal layer. The angular and wavelength response are considered. Special attention is paid to SPR excitation for variation of tilt angle and different angle of incident light. The influence of SPR of the pitch length and cell thickness is also considered.

  4. 114. WEST SIDE OF LIQUID OXYGEN CONTROL ROOM (205). LIQUID ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    114. WEST SIDE OF LIQUID OXYGEN CONTROL ROOM (205). LIQUID NITROGEN (LN2) SUBCOOLER ON LEFT; SKID 8, LIQUID OXYGEN CONTROLLER FOR SWITCHING BETWEEN RAPID-LOAD AND TOPPING ON RIGHT. LIQUID OXYGEN LINE FROM SKID 9A AT RIGHT EDGE OF PHOTO. - Vandenberg Air Force Base, Space Launch Complex 3, Launch Pad 3 East, Napa & Alden Roads, Lompoc, Santa Barbara County, CA

  5. Theoretical Aspects of Liquid Crystals and Liquid Crystalline Polymers

    E-print Network

    Feng, James J.

    ­solid duality gives rise to much of the ``anomalous'' behavior of liquid crystal- line materials. WhenTheoretical Aspects of Liquid Crystals and Liquid Crystalline Polymers James J. Feng Department,'' while the lack of strong positional order allows the material to flow like ordinary fluids. This liquid

  6. Apparatus and method for comparing corresponding acoustic resonances in liquids

    DOEpatents

    Sinha, Dipen N. (Los Almos, NM)

    1999-01-01

    Apparatus and method for comparing corresponding acoustic resonances in liquids. The present invention permits the measurement of certain characteristics of liquids which affect the speed of sound therein. For example, a direct correlation between the octane rating of gasoline and the speed of sound in a gasoline sample has been experimentally observed. Therefore, changes in the speed of sound therein can be utilized as a sensitive parameter for determining changes in composition of a liquid sample. The present apparatus establishes interference patterns inside of a liquid without requiring the use of very thin, rigorously parallel ceramic discs, but rather uses readily available piezoelectric transducers attached to the outside surface of the usual container for the liquid and located on the same side thereof in the vicinity of one another. That is, various receptacle geometries may be employed, and the driving and receiving transducers may be located on the same side of the receptacle. The cell may also be constructed of any material that is inert to the liquid under investigation. A single-transducer embodiment, where the same transducer provides the excitation to the sample container and receives signals impressed therein, is also described.

  7. Apparatus and method for comparing corresponding acoustic resonances in liquids

    DOEpatents

    Sinha, D.N.

    1999-03-23

    Apparatus and method are disclosed for comparing corresponding acoustic resonances in liquids. The present invention permits the measurement of certain characteristics of liquids which affect the speed of sound therein. For example, a direct correlation between the octane rating of gasoline and the speed of sound in a gasoline sample has been experimentally observed. Therefore, changes in the speed of sound therein can be utilized as a sensitive parameter for determining changes in composition of a liquid sample. The present apparatus establishes interference patterns inside of a liquid without requiring the use of very thin, rigorously parallel ceramic discs, but rather uses readily available piezoelectric transducers attached to the outside surface of the usual container for the liquid and located on the same side thereof in the vicinity of one another. That is, various receptacle geometries may be employed, and the driving and receiving transducers may be located on the same side of the receptacle. The cell may also be constructed of any material that is inert to the liquid under investigation. A single-transducer embodiment, where the same transducer provides the excitation to the sample container and receives signals impressed therein, is also described. 5 figs.

  8. Interacting Dirac liquid in three-dimensional semimetals

    NASA Astrophysics Data System (ADS)

    Hofmann, Johannes; Barnes, Edwin; Condensed Matter Theory Center Team

    2015-03-01

    We study theoretically the properties of the interacting Dirac liquid, a novel three-dimensional many-body system which was recently experimentally realized and in which the electrons have a chiral linear relativistic dispersion and a mutual Coulomb interaction. We find that the ``intrinsic'' Dirac liquid, where the Fermi energy lies exactly at the nodes of the band dispersion, displays unusual Fermi liquid properties, whereas the ``extrinsic'' system with finite detuning or doping behaves as a standard Landau Fermi liquid. We present analytical and numerical results for the self-energy and spectral function based on both Hartree-Fock and the random phase approximation (RPA) theories and compute the quasiparticle lifetime, residue, and renormalized Fermi velocity of the extrinsic Dirac liquid. A full numerical calculation of the extrinsic RPA spectral function indicates that the Fermi liquid description breaks down for large-energy excitations. Furthermore, we find an additional plasmaron quasiparticle sideband in the spectral function which is discontinuous around the Fermi energy. Our predictions should be observable in ARPES and STM measurements. This work is supported by LPS-CMTC.

  9. Extensible automated dispersive liquid-liquid microextraction.

    PubMed

    Li, Songqing; Hu, Lu; Chen, Ketao; Gao, Haixiang

    2015-05-01

    In this study, a convenient and extensible automated ionic liquid-based in situ dispersive liquid-liquid microextraction (automated IL-based in situ DLLME) was developed. 1-Octyl-3-methylimidazolium bis[(trifluoromethane)sulfonyl]imide ([C8MIM]NTf2) is formed through the reaction between [C8MIM]Cl and lithium bis[(trifluoromethane)sulfonyl]imide (LiNTf2) to extract the analytes. Using a fully automatic SPE workstation, special SPE columns packed with nonwoven polypropylene (NWPP) fiber, and a modified operation program, the procedures of the IL-based in situ DLLME, including the collection of a water sample, injection of an ion exchange solvent, phase separation of the emulsified solution, elution of the retained extraction phase, and collection of the eluent into vials, can be performed automatically. The developed approach, coupled with high-performance liquid chromatography-diode array detection (HPLC-DAD), was successfully applied to the detection and concentration determination of benzoylurea (BU) insecticides in water samples. Parameters affecting the extraction performance were investigated and optimized. Under the optimized conditions, the proposed method achieved extraction recoveries of 80% to 89% for water samples. The limits of detection (LODs) of the method were in the range of 0.16-0.45 ng mL(-1). The intra-column and inter-column relative standard deviations (RSDs) were <8.6%. Good linearity (r>0.9986) was obtained over the calibration range from 2 to 500 ng mL(-1). The proposed method opens a new avenue for automated DLLME that not only greatly expands the range of viable extractants, especially functional ILs but also enhances its application for various detection methods. Furthermore, multiple samples can be processed simultaneously, which accelerates the sample preparation and allows the examination of a large number of samples. PMID:25892068

  10. Diet - clear liquid

    MedlinePLUS

    ... juices without pulp, such as grape juice, filtered apple juice, and cranberry juice Soup broth (bouillon or ... might ask you to avoid liquids that have red coloring for some tests, like a colonoscopy.

  11. Liquid metal boiling inception

    NASA Technical Reports Server (NTRS)

    Sabin, C. M.; Poppendiek, H. F.; Mouritzen, G.; Meckel, P. T.; Cloakey, J. E.

    1972-01-01

    An experimental study of the inception of boiling in potassium in forced convection is reported. The boiler consisted of a 0.19-inch inside diameter, niobium-1% zirconium boiler tube approximately six feet long. Heating was accomplished by direct electrical tube wall conduction. Experiments were performed with both all-liquid fill and two-phase fill startup sequences and with a range of flow rates, saturation temperatures, inert gas levels, and fill liquid temperatures. Superheat of the liquid above the equilibrium saturation temperature was observed in all the experiments. Incipient boiling liquid superheat ranged from a few degrees to several hundred. Comparisons of these data with other data and with several analytical treatments are presented.

  12. Safer Liquid Natural Gas

    NASA Technical Reports Server (NTRS)

    1976-01-01

    After the disaster of Staten Island in 1973 where 40 people were killed repairing a liquid natural gas storage tank, the New York Fire Commissioner requested NASA's help in drawing up a comprehensive plan to cover the design, construction, and operation of liquid natural gas facilities. Two programs are underway. The first transfers comprehensive risk management techniques and procedures which take the form of an instruction document that includes determining liquid-gas risks through engineering analysis and tests, controlling these risks by setting up redundant fail safe techniques, and establishing criteria calling for decisions that eliminate or accept certain risks. The second program prepares a liquid gas safety manual (the first of its kind).

  13. Liquid crystal bilayer wall

    E-print Network

    Aksay, Ilhan A.

    to a liquid crystal solution of hexanol, cetylpyridinium chloride, and 0.2 M hydrochloric acid, and our hexanol, cetylpyridinium chloride, and 1 wt % aqueous NaCl solution.[1] This phase, which is optically

  14. Liquidity facilities and signaling

    E-print Network

    Arregui, Nicolás

    2010-01-01

    This dissertation studies the role of signaling concerns in discouraging access to liquidity facilities like the IMF contingent credit lines (CCL) and the Discount Window (DW). In Chapter 1, I analyze the introduction of ...

  15. Liquid medication administration

    MedlinePLUS

    ... cooking are accurate, but they spill easily. Oral syringes have some advantages for giving liquid medications. They ... easy to use. You can take a capped syringe containing a dose of medication to your child's ...

  16. The Liquid Nitrogen Fountain

    NASA Astrophysics Data System (ADS)

    McRae, Robin; Rahn, Jeffrey A.; Beamer, Timothy W.; Lebret, Norm

    2002-10-01

    Details of a demonstration using liquid nitrogen are presented. The demonstration is based on a 500-mL transparent polyethylene soft-drink bottle with a screw-on pop-up drink top. Prior to the demonstration, a balloon is placed over the popped-up spout of the bottle top. The bottle is filled with liquid nitrogen and the top, with the balloon affixed, is quickly put in place and screwed on tightly. As the liquid nitrogen in the bottle boils, the balloon inflates. When the balloon bursts the noise produced is far greater than would ordinarily be expected, and a fountain of liquid nitrogen and condensing water vapor shoots into the air above the bottle.

  17. Capacitance cell for liquids

    NASA Astrophysics Data System (ADS)

    Jacobs, D. T.; Greer, S. C.

    1980-07-01

    We present a simple and chemically inert, guarded cylindrical capacitance cell for liquids in the temperature range 170 to 370 K and at pressures near atmospheric. A precision in the dielectric constant of 2 ppm is realizable with this cell.

  18. Liquid cooled garments

    NASA Technical Reports Server (NTRS)

    1975-01-01

    Liquid cooled garments employed in several applications in which severe heat is encountered are discussed. In particular, the use of the garments to replace air line cooling units in a variety of industrial processing situations is discussed.

  19. Diet - full liquid

    MedlinePLUS

    ... liquid when they are at room temperature, like ice cream. It also includes: Strained creamy soups Tea Juice ... Butter, margarine, oil, cream, custard, and pudding Plain ice cream, frozen yogurt, and sherbet. Fruit ices and popsicles ...

  20. Liquid blocking check valve

    DOEpatents

    Merrill, John T. (Pleasant Hill, CA)

    1984-01-01

    A liquid blocking check valve useful particularly in a pneumatic system utilizing a pressurized liquid fill chamber. The valve includes a floatable ball disposed within a housing defining a chamber. The housing is provided with an inlet aperture disposed in the top of said chamber, and an outlet aperture disposed in the bottom of said chamber in an offset relation to said inlet aperture and in communication with a cutaway side wall section of said housing.

  1. Applications of ionic liquids.

    PubMed

    Patel, Divia Dinesh; Lee, Jong-Min

    2012-06-01

    Ionic liquids have recently gained popularity in the scientific community owing to their special properties and characteristics. One of the reasons why ionic liquids have been termed "green solvents" is due to their negligible vapour pressure. Their use in electrochemical, biological and metal extraction applications is discussed. Wide research has been carried out for their use in batteries, solar panels, fuel cells, drug deliveries and biomass pretreatments. This work aims to consolidate the various findings from previous works in these areas. PMID:22711528

  2. Liquid cooled helmet

    NASA Technical Reports Server (NTRS)

    Elkins, William (Inventor); Williams, Bill A. (Inventor)

    1979-01-01

    Liquid cooled helmet comprising a cap of flexible material adapted to fit the head of a person, cooling panels mounted inside the cap forming passageways for carrying a liquid coolant, the panels being positioned to engage the cranium and neck of a person wearing the helmet, inlet and outlet lines communicating with the passageways, and releasable straps for securing the helmet about the neck of the wearer.

  3. Liquid Level Sensing System

    NASA Technical Reports Server (NTRS)

    Korman, Valentin (Inventor); Wiley, John T. (Inventor); Duffell, Amanda G. (Inventor)

    2014-01-01

    A liquid level sensing system includes waveguides disposed in a liquid and distributed along a path with a gap between adjacent waveguides. A source introduces electromagnetic energy into the waveguides at a first end of the path. A portion of the electromagnetic energy exits the waveguides at a second end of the path. A detector measures the portion of the electromagnetic energy exiting the second end of the path.

  4. Tone-excited jet: Theory and experiments

    NASA Technical Reports Server (NTRS)

    Ahuja, K. K.; Lepicovsky, J.; Tam, C. K. W.; Morris, P. J.; Burrin, R. H.

    1982-01-01

    A detailed study to understand the phenomenon of broadband jet-noise amplification produced by upstream discrete-tone sound excitation has been carried out. This has been achieved by simultaneous acquisition of the acoustic, mean velocity, turbulence intensities, and instability-wave pressure data. A 5.08 cm diameter jet has been tested for this purpose under static and also flight-simulation conditions. An open-jet wind tunnel has been used to simulate the flight effects. Limited data on heated jets have also been obtained. To improve the physical understanding of the flow modifications brought about by the upstream discrete-tone excitation, ensemble-averaged schlieren photographs of the jets have also been taken. Parallel to the experimental study, a mathematical model of the processes that lead to broadband-noise amplification by upstream tones has been developed. Excitation of large-scale turbulence by upstream tones is first calculated. A model to predict the changes in small-scale turbulence is then developed. By numerically integrating the resultant set of equations, the enhanced small-scale turbulence distribution in a jet under various excitation conditions is obtained. The resulting changes in small-scale turbulence have been attributed to broadband amplification of jet noise. Excellent agreement has been found between the theory and the experiments. It has also shown that the relative velocity effects are the same for the excited and the unexcited jets.

  5. Atmospheric Excitation of Planetary Normal Modes

    NASA Technical Reports Server (NTRS)

    Tanimoto, Toshiro

    2001-01-01

    The objectives of this study were to: (1) understand the phenomenon of continuous free oscillations of the Earth and (2) examine the idea of using this phenomenon for planetary seismology. We first describe the results on (1) and present our evaluations of the idea (2) in the final section. In 1997, after almost forty years since the initial attempt by Benioff et al, continuous free oscillations of the Earth were discovered. Spheroidal fundamental modes between 2 and 7 millihertz are excited continuously with acceleration amplitudes of about 0.3-0.5 nanogals. The signal is now commonly found in virtually all data recorded by STS-1 type broadband seismometers at quiet sites. Seasonal variation in amplitude and the existence of two coupled modes between the atmosphere and the solid Earth support that these oscillations are excited by the atmosphere. Stochastic excitation due to atmospheric turbulence is a favored mechanism, providing a good match between theory and data. The atmosphere has ample energy to support this theory because excitation of these modes require only 500-10000 W whereas the atmosphere contains about 117 W of kinetic energy. An application of this phenomenon includes planetary seismology, because other planets may be oscillating due to atmospheric excitation. The interior structure of planets could be learned by determining the eigenfrequencies in the continuous free oscillations. It is especially attractive to pursue this idea for tectonically quiet planets, since quakes may be too infrequent to be recorded by seismic instruments.

  6. Femtosecond Timescale Evolution of Pyrrole Electronic Excitation

    NASA Astrophysics Data System (ADS)

    Montero, Raul; Conde, Alvaro Peralta; Ovejas, Virginia; Castano, Fernando; Longarte, Asier

    2012-06-01

    Pyrrole is a simple aromatic molecule with relevantchromophoric properties in biology. Although its apparent simplicity, it shows a complicated dynamics after excitation in the near part of the UV absorption spectrum, which results from the interplay between the bright ??^* and the dark dissociative ??^* electronic transitions. Herein, we present a time resolved study with ultrafast resolution on the relaxation dynamics of isolated pyrrole, after excitation in the 265-217 nm range. Two lifetimes of 19 and 15 fs, which are associated with the internal conversion from the bright 1B2 ??^* state and the propagation of the wavepacket on the ??^* state, respectively, are found in the studied energy interval. The work also explores the consequences of non resonant adiabatic excitation of the system when broadband femtosecond pulses are employed to prepare the molecule in the targeted electronic states, revealing the key implication of this type of coherent phenomena. The collected data reveal that the bright 1B2 ??^* state is adiabatically populated at excitation wavelengths far away from resonance, providing an efficient way to reach the ??^* state. The recorded transients are fit employing a coherent model that provides a comprehensive view of the dynamical processes pyrrole undergoes after excitation by ultrashort light pulses. M. N. R. Ashfold, B. Cronin, A. L. Devine, R. N. Dixon and M. G. D. Nix Science, 312, 1637-1640, 2006.

  7. Dimensional crossover in the purple bronze Li0.9Mo6O17.

    PubMed

    dos Santos, C A M; White, B D; Yu, Yi-Kuo; Neumeier, J J; Souza, J A

    2007-06-29

    Thermal expansion of Li0.9Mo6O17 is a-axis dominated which reduces the separation of the conducting chains at low temperature enhancing the interchain coupling. This destabilizes the Luttinger-liquid fixed point leading to an electronic charge- (or spin-) density wave dominated by Coulomb repulsion, as predicted by theories for Luttinger liquids. PMID:17678113

  8. Dimensional Crossover in the Purple Bronze Li0.9Mo6O17

    NASA Astrophysics Data System (ADS)

    Dos Santos, C. A. M.; White, B. D.; Yu, Yi-Kuo; Neumeier, J. J.; Souza, J. A.

    2007-06-01

    Thermal expansion of Li0.9Mo6O17 is a-axis dominated which reduces the separation of the conducting chains at low temperature enhancing the interchain coupling. This destabilizes the Luttinger-liquid fixed point leading to an electronic charge- (or spin-) density wave dominated by Coulomb repulsion, as predicted by theories for Luttinger liquids.

  9. Quantum Theory of Chiral Interactions in Cholesteric Liquid Crystals

    E-print Network

    A. S. Issaenko; A. B. Harris; T. C. Lubensky

    1998-10-15

    We study the effective chiral interaction between molecules arising from quantum dispersion interactions within a model in which a) the dominant excited states of a molecule form a band whose width is small compared to the average excitation energy and b) biaxial orientational correlation between adjacent molecules can be neglected. Previous treatments of quantum chiral interactions were based on a multipole expansion of the intermolecular interaction. However, because real liquid crystals are composed of elongated molecules, we utilize an expansion in terms of only coordinates transverse to the long molecular axes. We identify two distinct physical limits depending on whether one or both of the interacting molecules are excited in the virtual state. When both molecules are excited, our results are similar to those found previously by van der Meer et al. Previously unidentified terms in which only one molecule is excited involve the interactions of local dipole moments, which exist even when the global dipole moment of the molecule vanishes. We present analytic and numerical results for helical molecules. Our results do not indicate whether the dominant chiral interaction in cholesterics results from quantum or from steric interactions.

  10. Onset of quenching of the giant dipole resonance at high excitation energies

    NASA Astrophysics Data System (ADS)

    Santonocito, D.; Blumenfeld, Y.; Agodi, C.; Alba, R.; Bellia, G.; Coniglione, R.; Delaunay, F.; Del Zoppo, A.; Finocchiaro, P.; Hongmei, F.; Lima, V.; Maiolino, C.; Migneco, E.; Piattelli, P.; Sapienza, P.; Scarpaci, J. A.; Wieland, O.

    2014-11-01

    The evolution of the giant dipole resonance (GDR) properties in nuclei of mass A =120 to 132 has been investigated in an excitation energy range between 150 and 270 MeV through the study of complete and nearly complete fusion reactions using 116Sn beams at 17 A and 23 A MeV from the cyclotron of the Laboratorio Nazionale del Sud impinging on 12C and 24Mg targets. ? rays and light charged particles were detected using the multi-element detector array MEDEA in coincidence with evaporation residues detected by using mass and charge identification spectrometry with telescope (MACISTE). Light-charged-particle energy spectra were analyzed within the framework of a multiple-source-emission scenario by using a fitting procedure to determine the amount of pre-equilibrium emission and deduce the excitation energies reached in the compound nuclei. A detailed analysis of the ? -ray spectra and their comparison with statistical model calculations is presented. Evidence of a quenching of the GDR gamma yield was found at 270 MeV excitation energy. The quenching effect becomes progressively more important with increasing excitation energy, as observed when the comparison is extended to data from the reaction 36Ar+96Mo at 37 A MeV where hot nuclei were populated up to 430 MeV excitation energy. A coherent scenario emerges indicating the existence of a limiting excitation energy for the collective motion of about E*/A =2.1 MeV for systems of mass A =105 to 111 while a slightly lower value was observed for nuclei of mass A ˜132 . The existence of a possible link between GDR disappearance and the liquid-gas phase transition is discussed.

  11. Liquid crystalline composites containing phyllosilicates

    DOEpatents

    Chaiko, David J.

    2004-07-13

    The present invention provides phyllosilicate-polymer compositions which are useful as liquid crystalline composites. Phyllosilicate-polymer liquid crystalline compositions of the present invention can contain a high percentage of phyllosilicate while at the same time be transparent. Because of the ordering of the particles liquid crystalline composite, liquid crystalline composites are particularly useful as barriers to gas transport.

  12. Tailoring dye-sensitized upconversion nanoparticle excitation bands towards excitation wavelength selective imaging

    NASA Astrophysics Data System (ADS)

    Wu, Xiang; Lee, Hyungseok; Bilsel, Osman; Zhang, Yuanwei; Li, Zhanjun; Chen, Teresa; Liu, Yi; Duan, Chunying; Shen, Jie; Punjabi, Amol; Han, Gang

    2015-11-01

    One of the key roadblocks in UCNP development is its extremely limited choices of excitation wavelengths. We report a generic design to program UCNPs to possess highly tunable dye characteristic excitation bands. Using such distinctive properties, we were able to develop a new excitation wavelength selective security imaging. This work unleashed the greater freedom of the excitation wavelengths of the upconversion nanoparticles and we believe it is a game-changer in the field and this method will enable numerous applications that are currently limited by existing UCNPs.One of the key roadblocks in UCNP development is its extremely limited choices of excitation wavelengths. We report a generic design to program UCNPs to possess highly tunable dye characteristic excitation bands. Using such distinctive properties, we were able to develop a new excitation wavelength selective security imaging. This work unleashed the greater freedom of the excitation wavelengths of the upconversion nanoparticles and we believe it is a game-changer in the field and this method will enable numerous applications that are currently limited by existing UCNPs. Electronic supplementary information (ESI) available: Experimental details for the synthesis, TEM, FTIR spectra, absorption and PL spectra. See DOI: 10.1039/c5nr05437k

  13. Excited level populations and excitation kinetics of nonequilibrium ionizing argon discharge plasma of atmospheric pressure

    SciTech Connect

    Akatsuka, Hiroshi

    2009-04-15

    Population densities of excited states of argon atoms are theoretically examined for ionizing argon plasma in a state of nonequilibrium under atmospheric pressure from the viewpoint of elementary processes with collisional radiative model. The dependence of excited state populations on the electron and gas temperatures is discussed. Two electron density regimes are found, which are distinguished by the population and depopulation mechanisms for the excited states in problem. When the electron impact excitation frequency for the population or depopulation is lower than the atomic impact one, the electron density of the plasma is considered as low to estimate the population and depopulation processes. Some remarkable characteristics of population and depopulation mechanisms are found for the low electron density atmospheric plasma, where thermal relaxation by atomic collisions becomes the predominant process within the group of close-energy states in the ionizing plasma of atmospheric pressure, and the excitation temperature is almost the same as the gas temperature. In addition to the collisional relaxation by argon atoms, electron impact excitation from the ground state is also an essential population mechanism. The ratios of population density of the levels pairs, between which exists a large energy gap, include information on the electron collisional kinetics. For high electron density, the effect of atomic collisional relaxation becomes weak. For this case, the excitation mechanism is explained as electron impact ladderlike excitation similar to low-pressure ionizing plasma, since the electron collision becomes the dominant process for the population and depopulation kinetics.

  14. Visible fiber lasers excited by GaN laser diodes

    NASA Astrophysics Data System (ADS)

    Fujimoto, Yasushi; Nakanishi, Jun; Yamada, Tsuyoshi; Ishii, Osamu; Yamazaki, Masaaki

    2013-07-01

    This paper describes and discusses visible fiber lasers that are excited by GaN laser diodes. One of the attractive points of visible light is that the human eye is sensitive to it between 400 and 700 nm, and therefore we can see applications in display technology. Of course, many other applications exist. First, we briefly review previously developed visible lasers in the gas, liquid, and solid-state phases and describe the history of primary solid-state visible laser research by focusing on rare-earth doped fluoride media, including glasses and crystals, to clarify the differences and the merits of primary solid-state visible lasers. We also demonstrate over 1 W operation of a Pr:WPFG fiber laser due to high-power GaN laser diodes and low-loss optical fibers (0.1 dB/m) made by waterproof fluoride glasses. This new optical fiber glass is based on an AlF3 system fluoride glass, and its waterproof property is much better than the well known fluoride glass of ZBLAN. The configuration of primary visible fiber lasers promises highly efficient, cost-effective, and simple laser systems and will realize visible lasers with photon beam quality and quantity, such as high-power CW or tunable laser systems, compact ultraviolet lasers, and low-cost ultra-short pulse laser systems. We believe that primary visible fiber lasers, especially those excited by GaN laser diodes, will be effective tools for creating the next generation of research and light sources.

  15. Band excitation method applicable to scanning probe microscopy

    DOEpatents

    Jesse, Stephen; Kalinin, Sergei V.

    2015-08-04

    Scanning probe microscopy may include a method for generating a band excitation (BE) signal and simultaneously exciting a probe at a plurality of frequencies within a predetermined frequency band based on the excitation signal. A response of the probe is measured across a subset of frequencies of the predetermined frequency band and the excitation signal is adjusted based on the measured response.

  16. Optical Excitations in Carbon Architectures Based on Dodecadehydrotribenzo[18]annulene

    E-print Network

    Schlegel, H. Bernhard

    Optical Excitations in Carbon Architectures Based on Dodecadehydrotribenzo[18]annulene Smriti Anand The origin of excitations in multi-chromophore carbon network substructures based on dodecadehydrotriben- zo the origin of excitations in the macrocycles. The optical excitations in longer linear systems were found

  17. Effect of variable electromagnetic field on wave formation in a liquid metal film

    SciTech Connect

    Kazachov, I.V.; Kolesnichenko, A.F.

    1986-01-01

    The author investigate the characteristics of excitation and propagation of waves in a liquid metal film in the field of a horizontal electromagnetic wave having no component in the direction of motion of the film. The formulation of the problem is presented and a mathematical model of MHD flow in a liquid metal film is given. It is determined that the amplitude of perturbation of the free surface of the liquid metal film is determined mainly by electromagnetic and viscous forces, while the capillary and gravitational forces are negligibly small.

  18. Ripplon-induced coupling of photons to surface polaritons on liquid metals

    NASA Astrophysics Data System (ADS)

    Mills, D. L.

    1990-10-01

    It has been suggested that the surface of liquid Hg displays anomalous optical reflectivity, though whether or not this is the case remains unsettled from the experimental point of view. This paper explores an intrinsic mechanism which will result in an apparent optical anomaly at the surface of a liquid metal: the coupling of incident electromagnetic radiation to surface polaritons via thermally excited ripplons. We obtain a simple expression for the fraction of the incident electromagnetic radiation absorbed by this mechanism. For parameters characteristics f liquid Hg, the change in reflectivity associated with this mechanism is very small, unfortunately.

  19. Stable Vortex Generation in Liquid Filled Wells by Mode Conversion of Surface Acoustic Waves

    NASA Astrophysics Data System (ADS)

    Landskron, Johannes; Schmidt, Katrin; Kufner, Maria; Lindner, Gerhard

    The formation of stable vortex flow pattern has been observed at liquid filled aluminum wells of 15 to 30 mm diameter when Lamb waves are excited on the bottom of the wells by piezoelectric transducers operated at a frequency of 1 MHz. The shape of the vortex pattern changed with the position of the transducer. Strong differences in mixing times were observed between water and ethanol when the filling level was changed and a remarkable reduction of mixing time was achieved by the addition of a small amount of detergent to water at small filling levels. Besides mixing of liquids thermal equilibration within a liquid volume was accelerated by acoustic streaming.

  20. Electronic-excitation energy transfer in heterogeneous dye solutions under laser excitation

    SciTech Connect

    Levshin, L.V.; Mukushev, B.T.; Saletskii, A.M.

    1995-10-01

    An experimental study has been made of electronic-excitation energy transfer (EEET) among dye molecules of different types for different exciting-fight wavelengths and temperatures. Upon selective laser excitation of the donor, the inhomogeneous broadening of molecular levels increases the probability of EEET from the donor to acceptor molecules. The efficiency of this process is directly proportional to the acceptor molecule concentration and is temperature dependent. The EEET is accompanied by the spectral migration of energy among donor molecules, which reduces the fluorescence quantum efficiency of the donor. Increasing the frequency of the exciting light decreases in the donor fluorescence quantum efficiency. An increase in the acceptor molecule concentration results in a decrease of the spectral migration of excitation in the donor molecule system. 5 refs., 5 figs.

  1. The photodissociation and reaction dynamics of vibrationally excited molecules

    SciTech Connect

    Not Available

    1993-01-01

    We have used combined vibrational overtone excitation and laser induced fluorescence detection to study dissociation dynamics of hydroxylamine (NH[sub 2]OH), have performed our first laser induced grating experiments on water, and have begun assembling a new apparatus for preparing vibrationally excited molecules with simulated Raman excitation. We study role of vibrational excitation in photodissociation dynamics by using a vibrational state preparation technique, such as vibrational overtone excitation or stimulated Raman excitation, to create molecules with particular nuclear motions and then to excite that molecule to a dissociative electronic state.

  2. Collective excitations in itinerant spiral magnets

    SciTech Connect

    Kampf, A.P.

    1996-01-01

    We investigate the coupled charge and spin collective excitations in the spiral phases of the two-dimensional Hubbard model using a generalized random-phase approximation. Already for small doping the spin-wave excitations are strongly renormalized due to low-energy particle-hole excitations. Besides the three Goldstone modes of the spiral state the dynamical susceptibility reveals an extra zero mode for low doping and strong coupling values signaling an intrinsic instability of the homogeneous spiral state. In addition, near-zero modes are found in the vicinity of the spiral pitch wave number for out-of-plane spin fluctuations. Their origin is found to be the near degeneracy with staggered noncoplanar spiral states which, however, are not the lowest energy Hartree-Fock solutions among the homogeneous spiral states. {copyright} {ital 1996 The American Physical Society.}

  3. Shear layer excitation, experiment versus theory

    NASA Technical Reports Server (NTRS)

    Bechert, D. W.; Stahl, B.

    1984-01-01

    The acoustical excitation of shear layers is investigated. Acoustical excitation causes the so-called orderly structures in shear layers and jets. Also, the deviations in the spreading rate between different shear layer experiments are due to the same excitation mechanism. Measurements in the linear interaction region close to the edge from which the shear layer is shed are examined. Two sets of experiments (Houston 1981 and Berlin 1983/84) are discussed. The measurements were carried out with shear layers in air using hot wire anemometers and microphones. The agreement between these measurements and the theory is good. Even details of the fluctuating flow field correspond to theoretical predictions, such as the local occurrence of negative phase speeds.

  4. Phonon excitation by electron beams in nanographenes

    NASA Astrophysics Data System (ADS)

    Saavedra, J. R. M.; García de Abajo, F. Javier

    2015-09-01

    Electron beams have the ability of exciting vibrational modes (phonons) in molecules and nanoclusters, which can be currently probed with atomic spatial resolution through electron energy-loss spectroscopy (EELS). This scenario is similar to the excitation of plasmons with light, except that electrons allow much tighter spatial focusing. Additionally, phonons possess larger quality factors and lifetimes. In an effort to exploit these appealing properties, we theoretically investigate the interaction of focused electron beams with the vibrational modes of carbon nanographenes. The EELS probability is found to mimic the density of vibrational states, both of which evolve smoothly with cluster size towards the limit of extended graphene. Our results support the use of phonons as long-lived, tightly confined substitutes of plasmons, combined with electron-beam-mediated mode-selective excitation.

  5. Nanoscale control of phonon excitations in graphene

    PubMed Central

    Kim, Hyo Won; Ko, Wonhee; Ku, JiYeon; Jeon, Insu; Kim, Donggyu; Kwon, Hyeokshin; Oh, Youngtek; Ryu, Seunghwa; Kuk, Young; Hwang, Sung Woo; Suh, Hwansoo

    2015-01-01

    Phonons, which are collective excitations in a lattice of atoms or molecules, play a major role in determining various physical properties of condensed matter, such as thermal and electrical conductivities. In particular, phonons in graphene interact strongly with electrons; however, unlike in usual metals, these interactions between phonons and massless Dirac fermions appear to mirror the rather complicated physics of those between light and relativistic electrons. Therefore, a fundamental understanding of the underlying physics through systematic studies of phonon interactions and excitations in graphene is crucial for realising graphene-based devices. In this study, we demonstrate that the local phonon properties of graphene can be controlled at the nanoscale by tuning the interaction strength between graphene and an underlying Pt substrate. Using scanning probe methods, we determine that the reduced interaction due to embedded Ar atoms facilitates electron–phonon excitations, further influencing phonon-assisted inelastic electron tunnelling. PMID:26109454

  6. Excited light meson spectroscopy from lattice QCD

    SciTech Connect

    Christopher Thomas, Hadron Spectrum Collaboration

    2012-04-01

    I report on recent progress in calculating excited meson spectra using lattice QCD, emphasizing results and phenomenology. With novel techniques we can now extract extensive spectra of excited mesons with high statistical precision, including spin-four states and those with exotic quantum numbers. As well as isovector meson spectra, I will present new calculations of the spectrum of excited light isoscalar mesons, something that has up to now been a challenge for lattice QCD. I show determinations of the flavor content of these mesons, including the eta-eta' mixing angle, providing a window on annihilation dynamics in QCD. I will also discuss recent work on using lattice QCD to map out the energy-dependent phase shift in pi-pi scattering and future applications of the methodology to the study of resonances and decays.

  7. Charge-displacement analysis for excited states

    SciTech Connect

    Ronca, Enrico Tarantelli, Francesco; Dipartimento di Chimica, Biologia e Biotecnologie, Università degli Studi di Perugia, via Elce di Sotto 8, I-06123 Perugia ; Pastore, Mariachiara Belpassi, Leonardo; De Angelis, Filippo; Angeli, Celestino; Cimiraglia, Renzo

    2014-02-07

    We extend the Charge-Displacement (CD) analysis, already successfully employed to describe the nature of intermolecular interactions [L. Belpassi et al., J. Am. Chem. Soc. 132, 13046 (2010)] and various types of controversial chemical bonds [L. Belpassi et al., J. Am. Chem. Soc. 130, 1048 (2008); N. Salvi et al., Chem. Eur. J. 16, 7231 (2010)], to study the charge fluxes accompanying electron excitations, and in particular the all-important charge-transfer (CT) phenomena. We demonstrate the usefulness of the new approach through applications to exemplary excitations in a series of molecules, encompassing various typical situations from valence, to Rydberg, to CT excitations. The CD functions defined along various spatial directions provide a detailed and insightful quantitative picture of the electron displacements taking place.

  8. Charge-displacement analysis for excited states

    NASA Astrophysics Data System (ADS)

    Ronca, Enrico; Pastore, Mariachiara; Belpassi, Leonardo; De Angelis, Filippo; Angeli, Celestino; Cimiraglia, Renzo; Tarantelli, Francesco

    2014-02-01

    We extend the Charge-Displacement (CD) analysis, already successfully employed to describe the nature of intermolecular interactions [L. Belpassi et al., J. Am. Chem. Soc. 132, 13046 (2010)] and various types of controversial chemical bonds [L. Belpassi et al., J. Am. Chem. Soc. 130, 1048 (2008); N. Salvi et al., Chem. Eur. J. 16, 7231 (2010)], to study the charge fluxes accompanying electron excitations, and in particular the all-important charge-transfer (CT) phenomena. We demonstrate the usefulness of the new approach through applications to exemplary excitations in a series of molecules, encompassing various typical situations from valence, to Rydberg, to CT excitations. The CD functions defined along various spatial directions provide a detailed and insightful quantitative picture of the electron displacements taking place.

  9. Puzzles of excited charm meson masses

    E-print Network

    B. Ananthanarayan; Sunanda Banerjee; K. Shivaraj; A. Upadhyay

    2007-06-07

    We attempt a comprehensive analysis of the low lying charm meson states which present several puzzles, including the poor determination of masses of several non-strange excited mesons. We use the well-determined masses of the ground states and the strange first excited states to `predict' the mass of the non-strange first excited state in the framework of heavy hadron chiral perturbation theory, an approach that is complementary to the well-known analysis of Mehen and Springer. This approach points to values for the masses of these states that are smaller than the experimental determinations. We provide a critical assessment of these mass measurements and point out the need for new experimental information.

  10. Asymptotic wave propagation in excitable media.

    PubMed

    Bernus, Olivier; Vigmond, Edward

    2015-07-01

    Wave shape and velocity are important issues in reaction-diffusion systems, and are often the result of competition in media with heterogeneous conduction properties. Asymptotic wave front propagation at maximal conduction velocity has been previously reported in the context of anisotropic cardiac tissue, but it is unknown whether this is a universal property of excitable tissues where conduction velocity can be locally modulated by mechanisms other than anisotropy. Here, we investigate the impact of conduction heterogeneities and boundary effects on wave propagation in excitable media. Following a theoretical analysis, we find that wave-front cusps occur where local velocity is reduced and that asymptotic wave fronts propagate at the maximal translational conduction velocity. Simulations performed in different reaction-diffusion systems, including cardiac tissue, confirm our theoretical findings. We conclude that this property can be found in a wide range of reaction-diffusion systems with excitable dynamics and that asymptotic wave-front shapes can be predicted. PMID:26274110

  11. Artificial Excitation of Schumann Resonance with HAARP

    NASA Astrophysics Data System (ADS)

    Streltsov, A. V.; Chang, C. L.

    2014-12-01

    We report results from the experiment aimed at the artificial excitation of extremely-low-frequency (ELF) electromagnetic waves with frequencies corresponding to the frequency of Schumann resonance (typically, 7.5 - 8.0 Hz frequency range). Electromagnetic waves with these frequencies can form a standing pattern inside the spherical cavity formed by the surface of the earth and the ionosphere. In the experiment the ELF waves were excited by heating the ionosphere with X-mode HF electromagnetic waves generated by the High Frequency Active Auroral Research Program (HAARP) facility in Alaska. The experiment demonstrates that heating of the ionosphere can excite relatively large-amplitude electromagnetic waves with frequencies in the range of the Schumann resonance, when the ionosphere has a strong F-layer and an electric field greater than 5 mV/m is present in the E-region.

  12. High-energy excitations in silicon nanoparticles.

    PubMed

    Gali, Adam; Vörös, Márton; Rocca, Dario; Zimanyi, Gergely T; Galli, Giulia

    2009-11-01

    We have investigated high energy excitations in approximately 1-2 nm Si nanoparticles (NPs) by ab initio time-dependent density functional calculations, focusing on the influence on excitation spectra, of surface reconstruction, surface passivation by alkyl groups, and the interaction between NPs. We have found that surface reconstruction may change excitation spectra dramatically at both low and high energies above the gap; absorption may be enhanced nonlinearly by the presence of alkyl groups, compared to that of unreconstructed, hydrogenated Si NPs, and by the interaction between NPs. Our findings can help interpret the recent experiments on multielectron generation in colloidal semiconductor NPs as well as help optimize photovoltaic applications of NPs. PMID:19785388

  13. Bernoulli excitation and detection of gas bubbles.

    PubMed

    Telling, R H; Walton, A J

    2001-10-01

    A simple method is proposed for detecting and sizing bubbles in pipeline fluid flow. This is based on changing the pressure of the fluid, which in turn excites volume oscillations in the bubble. If the change in pressure is of sufficient brevity and magnitude, the transient distortion results in excitation of the bubble into radiative oscillation at its natural frequency. In a moving fluid, the Bernoulli equation predicts that such a pressure change can be achieved through a suitable gradient in the flow velocity. In the experiments described here, this is achieved by altering the cross-sectional area of the pipe in which the fluid is flowing. We demonstrate the efficacy of this excitation method and, by detecting the radiated sound using a nearby hydrophone, determine the size of individual bubbles from their characteristic oscillation frequency. PMID:11775661

  14. PHOTOEMISSION AS A PROBE OF THE COLLECTIVE EXCITATIONS IN CONDENSED MATTER SYSTEMS.

    SciTech Connect

    JOHNSON, P.D.; VALLA, T.

    2006-08-01

    New developments in instrumentation have recently allowed photoemission measurements to be performed with very high energy and momentum resolution.[1] This has allowed detailed studies of the self-energy corrections to the lifetime and mass renormalization of excitations in the vicinity of the Fermi level. These developments come at an opportune time. Indeed the discovery of high temperature superconductivity in the cuprates and related systems is presenting a range of challenges for condensed matter physics.[2] Does the mechanism of high T{sub c} superconductivity represent new physics? Do we need to go beyond Landau's concept of the Fermi liquid?[3] What, if any, is the evidence for the presence or absence of quasiparticles in the excitation spectra of these complex oxides? The energy resolution of the new instruments is comparable to or better than the energy or temperature scale of superconductivity and the energy of many collective excitations. As such, photoemission has again become recognized as an important probe of condensed matter. Studies of the high T{sub c} superconductors and related materials are aided by the observation that they are two dimensional. To understand this, we note that the photoemission process results in both an excited photoelectron and a photohole in the final state. Thus the experimentally measured photoemission peak is broadened to a width reflecting contributions from both the finite lifetime of the photohole and the momentum broadening of the outgoing photoelectron.

  15. Extended application of flow microfluorometry by means of dual laser excitation.

    PubMed

    Stöhr, M; Eipel, H; Goerttler, K; Vogt-Schaden, M

    1977-04-01

    A dual laser beam excitation device for flow analysis of biological particles has been developed. The aid of this arrangement is to increase the range of fluorescent agents employed so far in quantitative and qualitative cytochemistry. Combining an argon ion and a helium-cadmium laser two color fluorescence measurements were performed employing propidium iodide as a DNA stain and fluorescamine which stains total protein in fixed cells. Energy transfer processes between the antibiotic and DNA specific dye mithramycin and propidium iodide both being bound to nuclear chromatin were analyzed. Utilization of energy transfer processes is generally discussed as a mean to extract information about the structure and conformation of nuclear chromatin in situ. The application of a crypton ion laser with three lines near 400 nm and a single line at 350 nm having a light output in each range of nearly one Watt gives the opportunity of utilizing DNA fluorochromes which have an excitation maximum in the deep blue region, DNA spectra are shown employing mithramycin, the benzimidazol derivative 33258 (Hoechst) and the indol compound DAPI which has a high DNA specificity combined with a great stability under UV illumination. By separating two focussed laser beams at their intersecting points with the liquid sample stream the trajectory of each flowing cell crosses the beams sequentially, which causes a solitary dual excitation of each cell. The advantages of a solitary excitation device compared with a simultaneous one is discussed. PMID:870462

  16. Role of excited state solvent fluctuations on time-dependent fluorescence Stokes shift.

    PubMed

    Li, Tanping; Kumar, Revati

    2015-11-01

    We explore the connection between the solvation dynamics of a chromophore upon photon excitation and equilibrium fluctuations of the solvent. Using molecular dynamics simulations, fluorescence Stokes shift for the tryptophan in Staphylococcus nuclease was examined using both nonequilibrium calculations and linear response theory. When the perturbed and unperturbed surfaces exhibit different solvent equilibrium fluctuations, the linear response approach on the former surface shows agreement with the nonequilibrium process. This agreement is excellent when the perturbed surface exhibits Gaussian statistics and qualitative in the case of an isomerization induced non-Gaussian statistics. However, the linear response theory on the unperturbed surface breaks down even in the presence of Gaussian fluctuations. Experiments also provide evidence of the connection between the excited state solvent fluctuations and the total fluorescence shift. These observations indicate that the equilibrium statistics on the excited state surface characterize the relaxation dynamics of the fluorescence Stokes shift. Our studies specifically analyze the Gaussian fluctuations of the solvent in the complex protein environment and further confirm the role of solvent fluctuations on the excited state surface. The results are consistent with previous investigations, found in the literature, of solutes dissolved in liquids. PMID:26547170

  17. Role of excited state solvent fluctuations on time-dependent fluorescence Stokes shift

    NASA Astrophysics Data System (ADS)

    Li, Tanping; Kumar, Revati

    2015-11-01

    We explore the connection between the solvation dynamics of a chromophore upon photon excitation and equilibrium fluctuations of the solvent. Using molecular dynamics simulations, fluorescence Stokes shift for the tryptophan in Staphylococcus nuclease was examined using both nonequilibrium calculations and linear response theory. When the perturbed and unperturbed surfaces exhibit different solvent equilibrium fluctuations, the linear response approach on the former surface shows agreement with the nonequilibrium process. This agreement is excellent when the perturbed surface exhibits Gaussian statistics and qualitative in the case of an isomerization induced non-Gaussian statistics. However, the linear response theory on the unperturbed surface breaks down even in the presence of Gaussian fluctuations. Experiments also provide evidence of the connection between the excited state solvent fluctuations and the total fluorescence shift. These observations indicate that the equilibrium statistics on the excited state surface characterize the relaxation dynamics of the fluorescence Stokes shift. Our studies specifically analyze the Gaussian fluctuations of the solvent in the complex protein environment and further confirm the role of solvent fluctuations on the excited state surface. The results are consistent with previous investigations, found in the literature, of solutes dissolved in liquids.

  18. Localized magnetic excitation in the hybridization gap of YbAl3

    NASA Astrophysics Data System (ADS)

    Lawrence, J. M.; Goremychkin, E. A.; Bauer, E. D.

    2005-03-01

    YbAl3 is an intermediate valence (IV) compound which enters the coherent Fermi liquid phase below Tcoh = 50K.^[1] We have recently measured the magnetic scattering on the MAPS spectrometer at ISIS using high-quality single crystals. For T < 50K, the data can be fit as the sum of a background of nonmagnetic scattering and a pair of peaks at E1 = 50meV and E2 = 33meV which, in the extended zone scheme, scale with Q as the 4f form factor, as expected for magnetic scattering. The scattering near 50meV exhibits a peak in intensity near Q = (1.2, 0.5, 0.5) which also disperses somewhat with Q. Such Q-dependence is as expected for interband scattering across the hybridization gap in IV compounds. The scattering near 33meV, however, is independent of Q in both intensity and position and hence is the result of a spatially localized excitation. The energy of this excitation coincides with a deep minimum in the optical conductivity^[2], and hence the excitation energy lies in the middle of the hybridization gap. Both the magnetic excitation and the deep minimum in the conductivity gradually disappear above 50K, indicating that they are properties of the renormalized ground state. 1 A. L. Cornelius, et al, Phys. Rev. Lett. 88 (2002) 117201. 2. H. Okamura et al, Journ. Phys. Soc. Japan 73 (2004) 2045.

  19. Photoinduced electron transfer and geminate recombination in liquids on short time scales: Experiments and theory

    E-print Network

    Fayer, Michael D.

    Photoinduced electron transfer and geminate recombination in liquids on short time scales 23 February 2006 The coupled processes of intermolecular photoinduced forward electron transfer of the donor excited state due to forward electron transfer and the survival kinetics of the radicals produced

  20. Casimir effects for classical and quantum liquids in slab geometry: A brief review

    SciTech Connect

    Biswas, Shyamal

    2015-05-15

    We analytically explore Casimir effects for confinement of classical and quantum fluctuations in slab (film) geometry (i) for classical (critical) fluctuations over {sup 4}He liquid around the ? point, and (ii) for quantum (phonon) fluctuations of Bogoliubov excitations over an interacting Bose-Einstein condensate. We also briefly review Casimir effects for confinement of quantum vacuum fluctuations confined to two plates of different geometries.

  1. Laser two-photon ionization and autoionization spectroscopy of molecules in the liquid phase

    SciTech Connect

    Siomos, K.; Kourouklis, G.A.; Christophorou, L.G.

    1983-01-01

    The observation of autoionizing states of molecules in the liquid phase together with one- and two-photon ionization threshold measurements obtained using a laser conductivity technique are reported. Coherent versus resonant (stepwise) two-photon excitation in the photoionization process in solutions is discussed.

  2. Photophysical study and theoretical calculations of an ionic liquid crystal bearing oxadiazole

    NASA Astrophysics Data System (ADS)

    Pedro, Jorge A.; Mora, José R.; Westphal, Eduard; Gallardo, Hugo; Fiedler, Haidi D.; Nome, Faruk

    2012-05-01

    We report a detailed photophysical study of 1-dodecyl-4-[5-(4-dodecyloxyphenyl)-1,3,4-oxadiazole-2-yl]pyridinium bromide (454Do), a cationic amphiphile that behaves as a fluorescent liquid crystal. Excitation and emission spectra of the probe in different environments result in significant changes in quantum yields which are correlated with changes in lifetimes and theoretical calculations.

  3. Liquid chromatographic determination of polycyclic aromatic hydrocarbons in air particulate extracts

    SciTech Connect

    May, W.E.; Wise, S.A.

    1984-02-01

    Thirteen polycyclic aromatic hydrocarbons in urban particulate standard reference materials were successfully determined by reversed-phase liquid chromatography with spectro-fluorimetric detection at various combinations of excitation and emission wavelengths to optimise selectivity. The results were compared with those obtained by gas chromatography.

  4. Coherent excitation and control of surface phonons

    NASA Astrophysics Data System (ADS)

    Matsumoto, Yoshiyasu

    2006-03-01

    The excitation and control of nuclear wavepackets using tailored laser pulses have attracted a lot of interest recently and being realized mainly in gas-phase molecules. In contrast, there have been little studies on the coherent excitation and control for adsorbates particularly on metal surfaces. This is because dephasing is substantially rapid on metal surfaces due to efficient couplings between adsorbates and metals. Recently, we have demonstrated the time-domain observation of nuclear wavepacket dynamics of monolayer adsorbate by femtosecond time-resolved second harmonic generation (TRSHG). When metal surfaces covered with alkali metal atoms are irradiated by ultrafast laser pulses, coherent surface phonon modes are excited. The formation and dissipation processes of coherent surface phonons are probed by time-resolved second harmonic generation. SHG signal intensities are enhanced by alkali atoms adsorption by various resonant transitions in the adsorbate-substrate system. However, not all resonant electronic transitions lead to the generation of coherent stretching vibrations of alkali atoms. The measurements of TRSHG traces as a function of the excitation photon energy at a fixed alkali coverage indicate that resonant transitions between adsorbate-induced surface states is responsible for the coherent vibrational motions. By carefully examining the Cs coverage dependence of the TRSHG waveform, we found that TR-SHG traces show beating structures. This indicates that the oscillatory TR-SHG traces are contributed by at least two kinds of coherent surface phonon modes: the Cs-Pt stretching mode (2.3 THz) and the Rayleigh phonon mode (2.6 or 2.9 THz, depending on the Cs coverage). We used fs pulse trains with the repetition frequencies of 2.0 - 2.9 THz that are synthesized by using a spatial-light modulator as an excitation source for the coherent phonons. By tuning the pulse train frequency, we succeed in the selective excitation of a coherent phonon mode.

  5. Electron-impact vibrational excitation of cyclopropane

    NASA Astrophysics Data System (ADS)

    ?urík, R.; ?ársky, P.; Allan, M.

    2015-04-01

    We report a very detailed test of the ab initio discrete momentum representation (DMR) method of calculating vibrational excitation of polyatomic molecules by electron impact, by comparison of its results with an extensive set of experimental data, covering the entire range of scattering angles from 10? to 180? and electron energies from 0.4 to 20 eV. The DMR calculations were carried out by solving the two-channel Lippmann-Schwinger equation in the momentum space, and the interaction between the scattered electron and the target molecule was described by exact static-exchange potential corrected by a density functional theory (DFT) correlation-polarization interaction that models target's response to the field of incoming electron. The theory is found to quantitatively reproduce the measured spectra for all normal modes, even at the difficult conditions of extreme angles and at low energies, and thus provides full understanding of the excitation mechanism. It is shown that the overlap of individual vibrational bands caused by limited experimental resolution and rotational excitation must be properly taken into account for correct comparison of experiment and theory. By doing so, an apparent discrepancy between published experimental data could be reconciled. A substantial cross section is found for excitation of the non-symmetric HCH twisting mode ?4 of A1 ? symmetry by the 5.5 eV A2 ' resonance, surprisingly because the currently accepted selection rules predict this process to be forbidden. The DMR theory shows that the excitation is caused by an incoming electron in an f-wave of A2 ' symmetry which causes excitation of the non-symmetric HCH twisting mode ?4 of the A1 ? symmetry and departs in p- and f-waves of A2 ? symmetry.

  6. LMM Auger primary excitation spectra of copper

    NASA Astrophysics Data System (ADS)

    Pauly, N.; Tougaard, S.; Yubero, F.

    2014-12-01

    The shape and intensity of measured Auger peaks are strongly affected by extrinsic excitations due to electron transport out of the surface and to intrinsic excitations induced by the sudden creation of the two static core holes. Following a method developed for XPS in a previous work [N. Pauly, S. Tougaard, F. Yubero, Surf. Sci. 620 (2014) 17], we have calculated the effective energy-differential inelastic electron scattering cross-sections, including the effects of the surface and of the two core holes, within the dielectric response theory by means of the QUEELS-XPS software (QUantitative analysis of Electron Energy Losses at Surfaces for XPS). The Auger spectra are then modeled by convoluting this energy loss cross section with the primary excitation spectrum that accounts for all effects which are part of the initial Auger process, i.e. L-S coupling and vacancy satellite effects. The shape of this primary excitation spectrum is fitted to get close agreement between the theoretical and the experimental spectra obtained from X-ray excited Auger electron spectroscopy (XAES). We have performed these calculations of XAES spectra for various LMM Auger transitions of pure Cu (L3M45M45, L3M23M45, L3M23M23 and L2M45M45 transitions). We compare the resulting primary excitation spectra with theoretical results published in the literature and obtain reasonable quantitative agreement. In particular, we extract from experimental spectra quantitative intensities due to Coster-Kronig, shake-off and shake-up processes relative to the intensity from the “normal” Auger process.

  7. Excitation of Lunar Eccentricity by Planetary Resonances

    NASA Astrophysics Data System (ADS)

    Cuk, Matija

    2007-07-01

    The present free eccentricity (e) of the Moon's orbit is 0.052, and direct measurements using lunar laser-ranging (Williams et al. 2001) have shown it to be currently slowly increasing due to dominance of Earth's ocean tides over lunar satellite tides. Since the tidal e-excitation is just a side effect of orbital expansion, its significance for lunar e must have been greatest during the Hadean eon (4.5-4 Gyr ago). Therefore, tidal excitation is unlikely to have produced the present e of the Moon, as the efficiency of ocean tides must have been much lower in the distant past (Bills and Ray 1999 and references therein), and the Moon's e was likely damped, rather than excited, at this epoch. Kaula and Yoder (1976) proposed that lunar e might have been excited by a temporary capture in the Jovian evection resonance (at 53 R_E, when the lunar apsidal precession period equaled one Jovian year). We perfomed numerical integrations of that resonance passage, and found that the secular variations of Earth's orbit make capture impossible, but lead to hundreds of resonance passages as the resonance slightly shifts its location. These passages lead to a "random-walk" type changes in lunar eccentricity. If the pre-resonance eccentricity of the Moon was 0.005-0.01, the average post-resonance one is about 0.03-0.04 (with the tidal excitation subsequently bringing e up to its present level). We also discovered another planetary resonance of similar strength at about 46 R_E, involving the 1:2 commensurability with the 8-year 3:5 inequality between Earth and Venus. This resonance is strong enough to enhance small lunar eccentricities by a factor of few. A pre-resonance free e of 0.001 can plausibly be a product of tidal excitation, allowing for a total circularization of lunar orbit at some point in the past.

  8. The Theory and Applications of Parametric Excitation and Suppression of Oscillations in Continua: State of the Art

    E-print Network

    Kazachkov, Ivan V

    2015-01-01

    The results by development of physical, mathematical and numerical models for parametric excitation and suppression of oscillations on the interfaces separating continuous media, for carrying out computing, physical and natural experiments by revealing the new phenomena and parametric effects, and for their use in improvement the existing and creation the perspective highly efficient technological processes are presented. Scientific novelty of this work consists in development of the theory and applications of parametric excitation and suppression of oscillations on the boundaries of continua on the samples of three tasks classes: flat and radial spreading film flows of viscous incompressible liquids, conductive as well as non-conductive ones; surfaces of phase transition from a liquid state into a solid one; and heterogeneous granular media. The external actions considered are: alternating electromagnetic, vibration, acoustic and thermal fields. Along with linear the non-linear parametric oscillations are in...

  9. Spin excitations in the two-dimensional strongly coupled dimer system malachite

    NASA Astrophysics Data System (ADS)

    Canévet, E.; Fâk, B.; Kremer, R. K.; Chun, J. H.; Enderle, M.; Gordon, E. E.; Bettis, J. L.; Whangbo, M.-H.; Taylor, J. W.; Adroja, D. T.

    2015-02-01

    The mineral malachite, Cu 2(OD )2CO 3, has a quantum spin-liquid ground state and no long-range magnetic order down to at least T =0.4 K. Inelastic neutron scattering measurements show that the excitation spectrum consists of dispersive gapped singlet-triplet excitations, characteristic of spin-1/2 dimer-forming Heisenberg antiferromagnets. We identify a distinct two-dimensional dimerized coupling scheme with strong interdimer coupling J'/J1?0.3 that places malachite between strongly coupled alternating chains, square lattice antiferromagnets, and infinite-legged ladders. The geometry of the interaction scheme resembles the staggered dimer lattice, which may allow unconventional quantum criticality.

  10. Resonant laser excitation of molecular wires

    E-print Network

    Köhler, S; Camalet, S; Hänggi, P; Kohler, Sigmund; H\\"anggi, Peter

    2002-01-01

    We investigate the influence of external laser excitations on the average current through bridged molecules. For the computation of the current, we use a numerically very efficient formalism that is based on the Floquet solutions of the time-dependent molecule Hamiltonian. It is found that the current as a function of the laser frequency exhibits characteristic peaks originating from resonant excitations of electrons to bridge levels which are unoccupied in the absence of the radiation. The electrical current through the molecule can exhibit a drastic enhancement by several orders of magnitude.

  11. Gluonic excitations in the hadronic spectrum

    SciTech Connect

    Dudek, Jozef J.

    2014-06-01

    QCD at low energy features a gluonic field that is strongly coupled to itself and to quarks. I will present a summary of what we know about the role that excitations of the gluonic field play in determining the spectrum of meson resonances. Recent studies using lattice techniques have suggested a phenomenology of gluonic excitations within QCD that leads to hybrid mesons with both exotic and non-exotic quantum numbers. I will discuss these calculations and describe their relationship to current experimental knowledge and to forthcoming experiments at Jefferson Lab and elsewhere.

  12. Charmonium excited state spectrum in lattice QCD

    SciTech Connect

    Jozef Dudek; Robert Edwards; Nilmani Mathur; David Richards

    2008-02-01

    Working with a large basis of covariant derivative-based meson interpolating fields we demonstrate the feasibility of reliably extracting multiple excited states using a variational method. The study is performed on quenched anisotropic lattices with clover quarks at the charm mass. We demonstrate how a knowledge of the continuum limit of a lattice interpolating field can give additional spin-assignment information, even at a single lattice spacing, via the overlap factors of interpolating field and state. Excited state masses are systematically high with respect to quark potential model predictions and, where they exist, experimental states. We conclude that this is most likely a result of the quenched approximation.

  13. Charmonium excited state spectrum in lattice QCD

    SciTech Connect

    Dudek, Jozef J.; Edwards, Robert G.; Mathur, Nilmani; Richards, David G.

    2008-02-01

    Working with a large basis of covariant derivative-based meson interpolating fields we demonstrate the feasibility of reliably extracting multiple excited states using a variational method. The study is performed on quenched anisotropic lattices with clover quarks at the charm mass. We demonstrate how a knowledge of the continuum limit of a lattice interpolating field can give additional spin-assignment information, even at a single lattice spacing, via the overlap factors of interpolating field and state. Excited state masses are systematically high with respect to quark-potential model predictions and, where they exist, experimental states. We conclude that this is most likely a result of the quenched approximation.

  14. Exciting baryons: Now and in the future

    NASA Astrophysics Data System (ADS)

    Pennington, M. R.

    2012-04-01

    This is the final talk of NSTAR2011 conference. It is not a summary talk, but rather a looking forward to what still needs to be done in excited baryon physics. In particular, we need to hone our tools connecting experimental inputs with QCD. At present we rely on models that often have doubtful connections with the underlying theory, and this needs to be dramatically improved, if we are to reach definitive conclusions about the relevant degrees of freedom of excited baryons. Conclusions that we want to have by NSTAR2021.

  15. Exciting Baryons: now and in the future

    SciTech Connect

    Michael Pennington

    2012-04-01

    This is the final talk of NSTAR2011 conference. It is not a summary talk, but rather a looking forward to what still needs to be done in excited baryon physics. In particular, we need to hone our tools connecting experimental inputs with QCD. At present we rely on models that often have doubtful connections with the underlying theory, and this needs to be dramatically improved, if we are to reach definitive conclusions about the relevant degrees of freedom of excited baryons. Conclusions that we want to have by NSTAR2021.

  16. Double Photoionization of excited Lithium and Beryllium

    SciTech Connect

    Yip, Frank L.; McCurdy, C. William; Rescigno, Thomas N.

    2010-05-20

    We present total, energy-sharing and triple differential cross sections for one-photon, double ionization of lithium and beryllium starting from aligned, excited P states. We employ a recently developed hybrid atomic orbital/ numerical grid method based on the finite-element discrete-variable representation and exterior complex scaling. Comparisons with calculated results for the ground-state atoms, as well as analogous results for ground-state and excited helium, serve to highlight important selection rules and show some interesting effects that relate to differences between inter- and intra-shell electron correlation.

  17. Excited state contamination in nucleon structure calculations

    E-print Network

    Jeremy Green; Stefan Krieg; John Negele; Andrew Pochinsky; Sergey Syritsyn

    2011-11-28

    Among the sources of systematic error in nucleon structure calculations is contamination from unwanted excited states. In order to measure this systematic error, we vary the operator insertion time and source-sink separation independently. We compute observables for three source-sink separations between 0.93 fm and 1.39 fm using clover-improved Wilson fermions and pion masses as low as 150 MeV. We explore the use of a two-state model fit to subtract off the contribution from excited states.

  18. Relaxation channels of multi-photon excited xenon clusters.

    PubMed

    Serdobintsev, P Yu; Rakcheeva, L P; Murashov, S V; Melnikov, A S; Lyubchik, S; Timofeev, N A; Pastor, A A; Khodorkovskii, M A

    2015-09-21

    The relaxation processes of the xenon clusters subjected to multi-photon excitation by laser radiation with quantum energies significantly lower than the thresholds of excitation of atoms and ionization of clusters were studied. Results obtained by means of the photoelectron spectroscopy method showed that desorption processes of excited atoms play a significant role in the decay of two-photon excited xenon clusters. A number of excited states of xenon atoms formed during this process were discovered and identified. PMID:26395700

  19. Fig. 3. (a-b) excited image for coils 1 and 2 individually, (c) excited image for both waveforms applied

    E-print Network

    Fessler, Jeffrey A.

    Fig. 3. (a-b) excited image for coils 1 and 2 individually, (c) excited image for both waveforms applied simultaneously showing cancellation of excitation aliases (thin arrow) and filling of the desired pattern (thick arrow), and (d) the ideal simulated pattern. Parallel Excitation on a 3T Human MRI Scanner

  20. High resolution fluorescent bio-imaging with electron beam excitation.

    PubMed

    Kawata, Yoshimasa; Nawa, Yasunori; Inami, Wataru

    2014-11-01

    We have developed electron beam excitation assisted (EXA) optical microscope[1-3], and demonstrated its resolution higher than 50 nm. In the microscope, a light source in a few nanometers size is excited by focused electron beam in a luminescent film. The microscope makes it possible to observe dynamic behavior of living biological specimens in various surroundings, such as air or liquids. Scan speed of the nanometric light source is faster than that in conventional near-field scanning optical microscopes. The microscope enables to observe optical constants such as absorption, refractive index, polarization, and their dynamic behavior on a nanometric scale. The microscope opens new microscopy applications in nano-technology and nano-science.Figure 1(a) shows schematic diagram of the proposed EXA microscope. An electron beam is focused on a luminescent film. A specimen is put on the luminescent film directly. The inset in Fig. 1(a) shows magnified image of the luminescent film and the specimen. Nanometric light source is excited in the luminescent film by the focused electron beam. The nanometric light source illuminates the specimen, and the scattered or transmitted radiation is detected with a photomultiplier tube (PMT). The light source is scanned by scanning of the focused electron beam in order to construct on image. Figure 1(b) shows a luminescence image of the cells acquired with the EXA microscope, and Fig. 1(c) shows a phase contrast microscope image. Cells were observed in culture solution without any treatments, such as fixation and drying. The shape of each cell was clearly recognized and some bright spots were observed in cells. We believe that the bright spots indicated with arrows were auto-fluorescence of intracellular granules and light- grey regions were auto-fluorescence of cell membranes. It is clearly demonstrated that the EXA microscope is useful tool for observation of living biological cells in physiological conditions.jmicro;63/suppl_1/i16/DFU090F1F1DFU090F1Fig. 1.(a) Optical setup of EXA microscpe, and observation results of of living MARCO-expressing CHO cells with (b) EXA microscope and (c) phase contrast microscope. We proposed the EXA microscope as a technique with high spatial resolution beyond the diffraction limit of light. A spatial resolution greater than 100 nm was achieved for the EXA microscope and the dynamic behavior of moving nanoparticles in water was observed by time lapse imaging. We also demonstrated luminescence image of living cells in culture solution without any treatments. PMID:25359807