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Sample records for excite luttinger liquid

  1. Fractional Josephson current through a Luttinger liquid with topological excitations

    SciTech Connect

    Wang, Rui; Wang, Baigeng Xing, D.Y.

    2015-07-15

    Recently, the Majorana fermion has received great attentions due to its promising application in the fault-tolerant quantum computation. This application requires more accessible methods to detect the motion and braiding of the Majorana fermions. We use a Luttinger liquid ring to achieve this goal, where the ring geometry is nontrivial in the sense that it leads to fermion-parity-dependent topological excitations. First, we briefly review the essential physics of the Luttinger liquid and the Majorana fermion, in order to give an introduction of the general framework used in the following main work. Then, we theoretically investigated the DC Josephson effect between two topological superconductors via a Luttinger liquid ring. A low-energy effective Hamiltonian is derived to show the existence of the fractional Josephson current. Also, we find that the amplitude of the Josephson current, which is determined by the correlation function of Luttinger liquid, exhibits different behaviors in terms of the parity of Luttinger liquid due to the topological excitations. Our results suggest a possible method to detect the Majorana fermions and their tunneling process.

  2. Equilibration of a spinless Luttinger liquid.

    SciTech Connect

    Matveev, K. A.; Andreev, A. V.

    2012-01-01

    We study how a Luttinger liquid of spinless particles in one dimension approaches thermal equilibrium. Full equilibration requires processes of backscattering of excitations, which occur at energies of the order of the bandwidth. Such processes are not accounted for by the Luttinger-liquid theory. We treat the high-energy excitations as mobile impurities and derive an expression for the equilibration rate in terms of their spectrum. Our results apply at any interaction strength.

  3. 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.

  4. Equilibration in a chiral Luttinger liquid

    NASA Astrophysics Data System (ADS)

    Protopopov, I. V.; Gutman, D. B.; Mirlin, A. D.

    2015-05-01

    We explore the weak-strong-coupling Bose-Fermi duality in a model of a single-channel integer or fractional quantum Hall edge state with a finite-range interaction. The system is described by a chiral Luttinger liquid with nonlinear dispersion of bosonic and fermonic excitations. We use the bosonization, a unitary transformation, and a refermionization to map the system onto that of weakly interacting fermions at low temperature T or weakly interacting bosons at high T . We calculate the equilibration rate which is found to scale with temperature as T5 and T14 in the high-temperature ("bosonic") and the low-temperature ("fermonic") regimes, respectively. The relaxation rate of a hot particle with the momentum k in the fermonic regime scales as k7T7 .

  5. 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.

  6. 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).

  7. Compressible Strips, Chiral Luttinger Liquids, and All That Jazz

    NASA Astrophysics Data System (ADS)

    MacDonald, A. H.

    1996-03-01

    When the quantum Hall effect occurs in a two-dimensional electron gas, all low-energy elementary excitations are localized near the system edge. The edge acts in many ways like a one-dimensional ring of electrons, except that a finite current flows around the ring in equilibrium. This article is a brief and informal review of some of the physics of quantum Hall system edges. We discuss the implications of macroscopic {\\em compressible strip} models for microscopic {chiral Luttinger liquid} models and make an important distinction between the origin of non-Fermi-liquid behavior in fractional quantum Hall edges and in usual one-dimensional electron gas systems.

  8. Electrical and Thermal Transport in Inhomogeneous Luttinger Liquids

    NASA Astrophysics Data System (ADS)

    DeGottardi, Wade; Matveev, K. A.

    2015-06-01

    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.

  9. 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

  10. One-dimensional quantum liquids: Beyond the Luttinger liquid paradigm

    NASA Astrophysics Data System (ADS)

    Imambekov, Adilet; Schmidt, Thomas L.; Glazman, Leonid I.

    2012-07-01

    For many years, the Luttinger liquid theory has served as a useful paradigm for the description of one-dimensional (1D) quantum fluids in the limit of low energies. This theory is based on a linearization of the dispersion relation of the particles constituting the fluid. Recent progress in understanding 1D quantum fluids beyond the low-energy limit is reviewed, where the nonlinearity of the dispersion relation becomes essential. The novel methods which have been developed to tackle such systems combine phenomenology built on the ideas of the Fermi-edge singularity and the Fermi-liquid theory, perturbation theory in the interaction strength, and new ways of treating finite-size properties of integrable models. These methods can be applied to a wide variety of 1D fluids, from 1D spin liquids to electrons in quantum wires to cold atoms confined by 1D traps. Existing results for various dynamic correlation functions are reviewed, in particular, the dynamic structure factor and the spectral function. Moreover, it is shown how a dispersion nonlinearity leads to finite particle lifetimes and its impact on the transport properties of 1D systems at finite temperatures is discussed. The conventional Luttinger liquid theory is a special limit of the new theory, and the relation between the two is explained.

  11. 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.

  12. Attractive Tomonaga-Luttinger Liquid in a Quantum Spin Ladder

    NASA Astrophysics Data System (ADS)

    Jeong, M.; Mayaffre, H.; Berthier, C.; Schmidiger, D.; Zheludev, A.; Horvatić, M.

    2013-09-01

    We present NMR measurements of a strong-leg spin-1/2 Heisenberg antiferromagnetic ladder compound (C7H10N)2CuBr4 under magnetic fields up to 15 T in the temperature range from 1.2 K down to 50 mK. From the splitting of NMR lines, we determine the phase boundary and the order parameter of the low-temperature (three-dimensional) long-range-ordered phase. In the Tomonaga-Luttinger regime above the ordered phase, NMR relaxation reflects characteristic power-law decay of spin correlation functions as 1/T1∝T1/2K-1, which allows us to determine the interaction parameter K as a function of field. We find that field-dependent K varies within the 1Luttinger liquid.

  13. Attractive Tomonaga-Luttinger liquid in a quantum spin ladder.

    PubMed

    Jeong, M; Mayaffre, H; Berthier, C; Schmidiger, D; Zheludev, A; Horvatić, M

    2013-09-01

    We present NMR measurements of a strong-leg spin-1/2 Heisenberg antiferromagnetic ladder compound (C7H10N)2CuBr4 under magnetic fields up to 15 T in the temperature range from 1.2 K down to 50 mK. From the splitting of NMR lines, we determine the phase boundary and the order parameter of the low-temperature (three-dimensional) long-range-ordered phase. In the Tomonaga-Luttinger regime above the ordered phase, NMR relaxation reflects characteristic power-law decay of spin correlation functions as 1/T1∝T(1/2K-1), which allows us to determine the interaction parameter K as a function of field. We find that field-dependent K varies within the 1Luttinger liquid. PMID:25166688

  14. 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

  15. Spontaneously magnetized Tomonaga-Luttinger liquid in frustrated quantum antiferromagnets

    NASA Astrophysics Data System (ADS)

    Furuya, Shunsuke C.; Giamarchi, Thierry

    2014-05-01

    We develop a theory of spontaneously magnetized Tomonaga-Luttinger (TLL) liquid in geometrically frustrated quasi-one-dimensional quantum magnets by taking an S =1/2 ferrimagnet on a union-jack lattice as an example. We show that a strong frustration leads to a spontaneous magnetization because of the ferrimagnetic nature of lattice. Due to the ferrimagnetic order, the local magnetization has an incommensurate oscillation with the position. We show that the spontaneously magnetized TLL is smoothly connected to the existence of a Nambu-Goldstone boson in the canted ferrimagnetic phase of a two-dimensional frustrated antiferromagnet.

  16. The spin-current blockade in Luttinger liquid

    NASA Astrophysics Data System (ADS)

    Yao, Yao; Wu, Chang-Qin

    2009-02-01

    We investigate the spin-charge separation in the Luttinger liquid with a defective bond of controllable spin-dependent hopping by using the adaptive time-dependent density-matrix renormalization group method. The model is the non-half-filled Hubbard chain with this special bond, which is found to block the relevant spin current with little influence on charge current. We have considered the pure spin and charge currents induced by the voltage biases that are applied to the ideal leads attached at the ends of this Hubbard chain. The phenomenon is so robust that one may utilize it to observe the spin-charge separation directly.

  17. Universal Symmetry-Protected Resonances in a Spinful Luttinger Liquid

    NASA Astrophysics Data System (ADS)

    Hu, Yichen; Kane, Charles

    We study the problem of resonant tunneling through a quantum dot in a spinful Luttinger liquid. It provides the simplest example of a (0 + 1) d system with symmetry-protected topological phases. Transitions between different symmetry-protected topological phases separated by fixed points are achieved by tuning the system through resonance. For a particular interaction strength (Luttinger parameter gρ =1/3 , gσ = 1), we show that the problem is equivalent to a two channel SU (3) Kondo problem. Both problems can be mapped to a quantum Brownian motion model on a Kagome lattice, which in turn is related to quantum Brownian motion on a honeycomb lattice and the three channel SU (2) Kondo problem. Utilizing boundary conformal field theory, we find the universal peak conductance g*e2/h as well as dimensions of the leading relevant operators of the problem. This allows us to compute the scaling behavior of the resonance line-shape as a function of temperature. We also established the fact that the fixed point quantum Brownian motion on both generalized honeycomb lattice(SU(2)k Kondo) and generalized Kagome lattice(SU(k)2 Kondo) flow into are the same (with k = 3 our original resonant tunneling problem).

  18. Tunneling between helical Majorana modes and helical Luttinger liquids

    NASA Astrophysics Data System (ADS)

    Chao, Sung-Po; Schmidt, Thomas L.; Chung, Chung-Hou

    2015-06-01

    We propose and study the charge transport through single and double quantum point contacts setup between helical Majorana modes and an interacting helical Luttinger liquid. We show that the differential conductance decreases for stronger repulsive interactions and that the point contacts become insulating above a critical interaction strength. For a single-point contact, the differential conductance as a function of bias voltage shows a series of peaks due to Andreev reflection of electrons in the Majorana modes. In the case of two point contacts, interference phenomena make the structure of the individual resonance peaks less universal and show modulations with different separation distance between the contacts. For small separation distance, the overall features remain similar to the case of a single-point contact.

  19. 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.

  20. 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.

  1. One-Dimensional Liquid 4He: Dynamical Properties beyond Luttinger-Liquid Theory

    NASA Astrophysics Data System (ADS)

    Bertaina, G.; Motta, M.; Rossi, M.; Vitali, E.; Galli, D. E.

    2016-04-01

    We compute the zero-temperature dynamical structure factor of one-dimensional liquid 4He by means of state-of-the-art quantum Monte Carlo and analytic continuation techniques. By increasing the density, the dynamical structure factor reveals a transition from a highly compressible critical liquid to a quasisolid regime. In the low-energy limit, the dynamical structure factor can be described by the quantum hydrodynamic Luttinger-liquid theory, with a Luttinger parameter spanning all possible values by increasing the density. At higher energies, our approach provides quantitative results beyond the Luttinger-liquid theory. In particular, as the density increases, the interplay between dimensionality and interaction makes the dynamical structure factor manifest a pseudo-particle-hole continuum typical of fermionic systems. At the low-energy boundary of such a region and moderate densities, we find consistency, within statistical uncertainties, with predictions of a power-law structure by the recently developed nonlinear Luttinger-liquid theory. In the quasisolid regime, we observe a novel behavior at intermediate momenta, which can be described by new analytical relations that we derive for the hard-rods model.

  2. One-Dimensional Liquid ^{4}He: Dynamical Properties beyond Luttinger-Liquid Theory.

    PubMed

    Bertaina, G; Motta, M; Rossi, M; Vitali, E; Galli, D E

    2016-04-01

    We compute the zero-temperature dynamical structure factor of one-dimensional liquid ^{4}He by means of state-of-the-art quantum Monte Carlo and analytic continuation techniques. By increasing the density, the dynamical structure factor reveals a transition from a highly compressible critical liquid to a quasisolid regime. In the low-energy limit, the dynamical structure factor can be described by the quantum hydrodynamic Luttinger-liquid theory, with a Luttinger parameter spanning all possible values by increasing the density. At higher energies, our approach provides quantitative results beyond the Luttinger-liquid theory. In particular, as the density increases, the interplay between dimensionality and interaction makes the dynamical structure factor manifest a pseudo-particle-hole continuum typical of fermionic systems. At the low-energy boundary of such a region and moderate densities, we find consistency, within statistical uncertainties, with predictions of a power-law structure by the recently developed nonlinear Luttinger-liquid theory. In the quasisolid regime, we observe a novel behavior at intermediate momenta, which can be described by new analytical relations that we derive for the hard-rods model. PMID:27081985

  3. dc and ac Josephson effect in a superconductor-Luttinger-liquid-superconductor system

    NASA Astrophysics Data System (ADS)

    Fazio, Rosario; Hekking, F. W. J.; Odintsov, A. A.

    1996-03-01

    We calculate both the dc and the ac Josephson current through a one-dimensional system of interacting electrons, connected to two superconductors by tunnel junctions. We treat the (repulsive) Coulomb interaction in the framework of the one-channel, spin-1/2 Luttinger model. The Josephson current is obtained for two geometries of experimental relevance: a quantum wire and a ring. At zero temperature, the critical current is found to decay algebraically with increasing distance d between the junctions. The decay is characterized by an exponent which depends on the strength of the interaction. At finite temperatures T, lower than the superconducting transition temperature Tc, there is a crossover from algebraic to exponential decay of the critical current as a function of d, at a distance of the order of ħvF/kBT. Moreover, the dependence of critical current on temperature shows nonmonotonic behavior. If the Luttinger liquid is confined to a ring of circumference L, coupled capacitively to a gate voltage and threaded by a magnetic flux, the Josephson current shows remarkable parity effects under the variation of these parameters. For some values of the gate voltage and applied flux, the ring acts as a π junction. These features are robust against thermal fluctuations up to temperatures on the order of ħvF/kBL. For the wire geometry, we have also studied the ac-Josephson effect. The amplitude and the phase of the time-dependent Josephson current are affected by electron-electron interactions. Specifically, the amplitude shows pronounced oscillations as a function of the bias voltage due to the difference between the velocities of spin and charge excitations in the Luttinger liquid. Therefore, the ac-Josephson effect can be used as a tool for the observation of spin-charge separation.

  4. 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

  5. ESR modes in a Strong-Leg Ladder in the Tomonaga-Luttinger Liquid Phase

    NASA Astrophysics Data System (ADS)

    Zvyagin, S.; Ozerov, M.; Maksymenko, M.; Wosnitza, J.; Honecker, A.; Landee, C. P.; Turnbull, M.; Furuya, S. C.; Giamarchi, T.

    Magnetic excitations in the strong-leg quantum spin ladder compound (C7H10N)2CuBr4 (known as DIMPY) in the field-induced Tomonaga-Luttinger spin liquid phase are studied by means of high-field electron spin resonance (ESR) spectroscopy. The presence of a gapped ESR mode with unusual non-linear frequency-field dependence is revealed experimentally. Using a combination of analytic and exact diagonalization methods, we compute the dynamical structure factor and identify this mode with longitudinal excitations in the antisymmetric channel. We argue that these excitations constitute a fingerprint of the spin dynamics in a strong-leg spin-1/2 Heisenberg antiferromagnetic ladder and owe its ESR observability to the uniform Dzyaloshinskii-Moriya interaction. This work was partially supported by the DFG and Helmholtz Gemeinschaft (Germany), Swiss SNF under Division II, and ERC synergy UQUAM project. We acknowledge the support of the HLD at HZDR, member of the European Magnetic Field Laboratory (EMFL).

  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.

    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

  8. Electron spin resonance modes in a strong-leg ladder in the Tomonaga-Luttinger liquid phase

    NASA Astrophysics Data System (ADS)

    Ozerov, M.; Maksymenko, M.; Wosnitza, J.; Honecker, A.; Landee, C. P.; Turnbull, M. M.; Furuya, S. C.; Giamarchi, T.; Zvyagin, S. A.

    2015-12-01

    Magnetic excitations in the strong-leg quantum spin ladder compound (C7H10N) 2CuBr4 (known as DIMPY) in the field-induced Tomonaga-Luttinger spin-liquid phase are studied by means of high-field electron spin resonance (ESR) spectroscopy. The presence of a gapped ESR mode with unusual nonlinear frequency-field dependence is revealed experimentally. Using a combination of analytic and exact-diagonalization methods, we compute the dynamical structure factor and identify this mode with longitudinal excitations in the antisymmetric channel. We argue that these excitations constitute a fingerprint of the spin dynamics in a strong-leg spin-1/2 Heisenberg antiferromagnetic ladder and owe their ESR observability to the uniform Dzyaloshinskii-Moriya interaction.

  9. Escort distribution function of work done and diagonal entropies in quenched Luttinger liquids

    NASA Astrophysics Data System (ADS)

    Dóra, Balázs

    2014-12-01

    We study the escort probability distribution function of work done during an interaction quantum quench of Luttinger liquids. It crosses over from the thermodynamic to the small system limit with increasing a , which is the order of the escort distribution, and depends on the universal combination [| Ki-Kf|/(Ki+KF) ] a , with Ki, Kf the initial and final Luttinger liquid parameters, respectively. From its characteristic function, the diagonal Rényi entropies and the many-body inverse participation ratio (IPR) are determined to evaluate the information content of the time-evolved wave function in terms of the eigenstates of the final Hamiltonian. The hierarchy of overlaps is dominated by that of the ground states. The IPR exhibits a crossover from Gaussian to power-law decay with increasing interaction quench parameter.

  10. Local spectral properties of Luttinger liquids: scaling versus nonuniversal energy scales.

    PubMed

    Schuricht, D; Andergassen, S; Meden, V

    2013-01-01

    Motivated by recent scanning tunneling and photoemission spectroscopy measurements on self-organized gold chains on a germanium surface, we reinvestigate the local single-particle spectral properties of Luttinger liquids. In the first part we use the bosonization approach to exactly compute the local spectral function of a simplified field theoretical low-energy model and take a closer look at scaling properties as a function of the ratio of energy and temperature. Translational-invariant Luttinger liquids as well as those with an open boundary (cut chain geometry) are considered. We explicitly show that the scaling functions of both set-ups have the same analytical form. The scaling behavior suggests a variety of consistency checks which can be performed on measured data to experimentally verify Luttinger liquid behavior. In the second part we approximately compute the local spectral function of a microscopic lattice model-the extended Hubbard model-close to an open boundary using the functional renormalization group. We show that it follows the field theoretical prediction in the low-energy regime as a function of energy and temperature, and point out the importance of nonuniversal energy scales inherent to any microscopic model. The spatial dependence of this spectral function is characterized by oscillatory behavior and an envelope function which follows a power law in accordance with the field theoretical continuum model. Interestingly, for the lattice model we find a phase shift which is proportional to the two-particle interaction and not accounted for in the standard bosonization approach to Luttinger liquids with an open boundary. We briefly comment on the effects of several one-dimensional branches cutting the Fermi energy and Rashba spin-orbit interaction. PMID:23221026

  11. One-dimensional rings with barriers: a Luttinger liquid approach to precision measurement

    NASA Astrophysics Data System (ADS)

    Ragole, Stephen; Taylor, Jacob

    2015-05-01

    Recent experiments have realized ring shaped traps for ultracold atoms in which the atoms can be manipulated in several interesting ways. Here, we consider 1D ring system with a moving weak barrier within the framework of Luttinger liquid theory. We find that classical theory suggests high precision sensors can be constructed from these systems; we extend these results into the quantum regime. Funding provided by the Physics Frontier Center at the JQI and by DARPA QUASAR.

  12. Tunneling spectroscopy of a spiral Luttinger liquid in contact with superconductors

    NASA Astrophysics Data System (ADS)

    Liu, Dong E.; Levchenko, Alex

    2014-03-01

    One-dimensional wires with Rashba spin-orbit coupling, magnetic field, and strong electron-electron interactions are described by a spiral Luttinger liquid model. We develop a theory to investigate the tunneling density of states into a spiral Luttinger liquid in contact with superconductors at its two ends. This approach provides a way to disentangle the delicate interplay between superconducting correlations and strong electron interactions. If the wire-superconductor boundary is dominated by Andreev reflection, we find that in the vicinity of the interface the zero-bias tunneling anomaly reveals a power law enhancement with the unusual exponent. This zero-bias due to Andreev reflections may coexist and thus mask possible peak due to Majorana bound states. Far away from the interface strong correlations inherent to the Luttinger liquid prevail and restore conventional suppression of the tunneling density of states at the Fermi level, which acquires a Friedel-like oscillatory envelope with the period renormalized by the strength of the interaction. D.E.L. was supported by Michigan State University and in part by ARO through Contract No. W911NF-12-1-0235. A.L. acknowledges support from NSF under Grant No. PHYS-1066293, and the hospitality of the Aspen Center for Physics.

  13. Luttinger-liquid behavior and superconducting correlations in {ital t}-{ital J} ladders

    SciTech Connect

    Hayward, C.A.; Poilblanc, D.

    1996-05-01

    The low-energy behavior of the isotropic {ital t}-{ital J} ladder system is investigated using exact diagonalization techniques, specifically finding the Drude weight, the charge velocity, and the compressibility. By applying the ideas of Luttinger-liquid theory, we determine the correlation exponent {ital K}{sub {rho}} which defines the behavior of the long-range correlations in the system. The boundary to phase separation is determined and a phase diagram is presented. At low electron density, a Tomonaga-Luttinger-like phase is stabilized while at higher electron densities a gapped phase with power law pairing correlations is stabilized: A large region of this gapped phase is found to exhibit dominant superconducting correlations. {copyright} {ital 1996 The American Physical Society.}

  14. 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 .

  15. 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.

  16. Topological Protection from Random Rashba Spin-Orbit Backscattering: Ballistic Transport in a Helical Luttinger Liquid

    NASA Astrophysics Data System (ADS)

    Xie, Hong-Yi; Li, Heqiu; Chou, Yang-Zhi; Foster, Matthew S.

    2016-02-01

    The combination of Rashba spin-orbit coupling and potential disorder induces a random current operator for the edge states of a 2D topological insulator. We prove that charge transport through such an edge is ballistic at any temperature, with or without Luttinger liquid interactions. The solution exploits a mapping to a spin 1 /2 in a time-dependent field that preserves the projection along one randomly undulating component (integrable dynamics). Our result is exact and rules out random Rashba backscattering as a source of temperature-dependent transport, absent integrability-breaking terms.

  17. Cold atoms in one-dimensional rings: a Luttinger liquid approach to precision measurement

    NASA Astrophysics Data System (ADS)

    Ragole, Stephen; Taylor, Jacob

    Recent experiments have realized ring shaped traps for ultracold atoms. We consider the one-dimensional limit of these ring systems with a moving weak barrier, such as a blue-detuned laser beam. In this limit, we employ Luttinger liquid theory and find an analogy with the superconducting charge qubit. In particular, we find that strongly-interacting atoms in such a system could be used for precision rotation sensing. We compare the performance of this new sensor to the state of the art non-interacting atom interferometry. Funding provided by the Physics Frontier Center at the JQI and by DARPA QUASAR.

  18. Topological Protection from Random Rashba Spin-Orbit Backscattering: Ballistic Transport in a Helical Luttinger Liquid.

    PubMed

    Xie, Hong-Yi; Li, Heqiu; Chou, Yang-Zhi; Foster, Matthew S

    2016-02-26

    The combination of Rashba spin-orbit coupling and potential disorder induces a random current operator for the edge states of a 2D topological insulator. We prove that charge transport through such an edge is ballistic at any temperature, with or without Luttinger liquid interactions. The solution exploits a mapping to a spin 1/2 in a time-dependent field that preserves the projection along one randomly undulating component (integrable dynamics). Our result is exact and rules out random Rashba backscattering as a source of temperature-dependent transport, absent integrability-breaking terms. PMID:26967434

  19. Surface Tomonaga-Luttinger-Liquid State on Bi /InSb (001 )

    NASA Astrophysics Data System (ADS)

    Ohtsubo, Yoshiyuki; Kishi, Jun-ichiro; Hagiwara, Kenta; Le Fvre, Patrick; Bertran, Franois; Taleb-Ibrahimi, Amina; Yamane, Hiroyuki; Ideta, Shin-ichiro; Matsunami, Masaharu; Tanaka, Kiyohisa; Kimura, Shin-ichi

    2015-12-01

    A 1D metallic surface state was created on an anisotropic InSb(001) surface covered with Bi. Angle-resolved photoelectron spectroscopy (ARPES) showed a 1D Fermi contour with almost no 2D distortion. Close to the Fermi level (EF), the angle-integrated photoelectron spectra showed power-law scaling with the binding energy and temperature. The ARPES plot above EF, obtained thanks to a thermally broadened Fermi edge at room temperature, showed a 1D state with continuous metallic dispersion across EF and power-law intensity suppression around EF. These results strongly suggest a Tomonaga-Luttinger liquid on the Bi /InSb (001 ) surface.

  20. Spin-orbit interactions in a helical Luttinger liquid with a Kondo impurity

    NASA Astrophysics Data System (ADS)

    Eriksson, Erik

    2013-03-01

    We study the transport properties of a helical Luttinger liquid with a Kondo impurity and spin-orbit interactions. Such a system, which may be realized at the edge of a quantum spin Hall insulator with a gate-induced electric field, provides a mechanism to electrically control the conductance. A Rashba spin-orbit interaction may even change the nature of the Kondo screening [Eriksson et al., Phys. Rev. B 86, 161103(R) (2012)]. Considering other types of spin-orbit interactions, together with an extended non-equilibrium analysis, we further improve the understanding of these phenomena.

  1. Topological protection from random Rashba spin-orbit backscattering: Ballistic transport in a helical Luttinger liquid

    NASA Astrophysics Data System (ADS)

    Xie, Hong-Yi; Li, Heqiu; Chou, Yang-Zhi; Foster, Matthew

    Rashba spin-orbit coupling enables irrelevant backscattering in a time-reversal symmetric helical Luttinger liquid (HLL). We study the Landauer conductance G of a HLL in the presence of random Rashba coupling as well as the density-density (Luttinger) interaction. We prove that the transport is purely ballistic (G =e2 / h) at any temperature due to the topology. The solution involves a unitary transformation that corresponds to a spin-1/2 in a random, two-component time-dependent magnetic field that preserves the projection of the spin along one fluctuating component (integrable dynamics). Our result is exact for a fixed realization of disorder, and avoids difficulties that arise in disorder-averaged perturbative calculations such as bosonization. We compare the HLL with random Rashba coupling to the Dyson model describing an ordinary spinless quantum wire with particle-hole symmetry, which exhibits non-ballistic transport even at zero temperature. This research was supported by the Welch Foundation under Grant No. C-1809 and by an Alfred P. Sloan Research Fellowship No. BR2014-035.

  2. Long-lived binary tunneling spectrum in the quantum Hall Tomonaga-Luttinger liquid

    NASA Astrophysics Data System (ADS)

    Washio, K.; Nakazawa, R.; Hashisaka, M.; Muraki, K.; Tokura, Y.; Fujisawa, T.

    2016-02-01

    The existence of long-lived nonequilibrium states without showing thermalization, which has previously been demonstrated in time evolution of ultracold atoms, suggests the possibility of their spatial analog in transport behavior of interacting electrons in solid-state systems. Here we report long-lived nonequilibrium states in one-dimensional edge channels in the integer quantum Hall regime. An indirect heating scheme in a counterpropagating configuration is employed to generate a nontrivial binary spectrum consisting of high- and low-temperature components. This unusual spectrum is sustained even after traveling 5-10 μ m , much longer than the length for electronic relaxation (about 0.1 μ m ), without showing significant thermalization. This observation is consistent with the integrable model of Tomonaga-Luttinger liquid. The long-lived spectrum implies that the system is well described by noninteracting plasmons, which are attractive for carrying information for a long distance.

  3. Generalized Gibbs ensemble and work statistics of a quenched Luttinger liquid

    NASA Astrophysics Data System (ADS)

    Dóra, Balázs; Bácsi, Ádám; Zaránd, Gergely

    2012-10-01

    We analyze the probability distribution function (PDF) of work done on a Luttinger liquid for an arbitrary finite duration interaction quench and show that it can be described in terms of a generalized Gibbs ensemble. We construct the corresponding density matrix with explicit intermode correlations, and determine the duration and interaction dependence of the probability of an adiabatic transition and the PDF of nonadiabatic processes. In the thermodynamic limit, the PDF of work exhibits a non-Gaussian maximum around the excess heat, carrying almost all the spectral weight. In contrast, in the small system limit most spectral weight is carried by a delta peak at the energy of the adiabatic process, and an oscillating PDF with dips at energies commensurate to the quench duration and with an exponential envelope develops. Relevance to cold atom experiments is also discussed.

  4. Charge transport in a Tomonaga-Luttinger liquid: Effects of pumping and bias

    NASA Astrophysics Data System (ADS)

    Agarwal, Amit; Sen, Diptiman

    2007-07-01

    We study the current produced in a Tomonaga-Luttinger liquid by an applied bias and by weak, pointlike impurity potentials which are oscillating in time. We use bosonization to perturbatively calculate the current up to second order in the impurity potentials. In the regime of small bias and low pumping frequency, both the dc and ac components of the current have power-law dependences on the bias and pumping frequencies with an exponent 2K-1 for spinless electrons, where K is the interaction parameter. For K<1/2 , the current grows large for special values of the bias. For noninteracting electrons with K=1 , our results agree with those obtained using Floquet scattering theory for Dirac fermions. We also discuss the cases of extended impurities and of spin- 1/2 electrons.

  5. 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

  6. 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.

  7. Wilson ratio of a Tomonaga-Luttinger liquid in a spin-1/2 Heisenberg ladder

    NASA Astrophysics Data System (ADS)

    Hong, Tao; Ninios, K.; Kim, Y. H.; Manabe, T.; Hotta, C.; Tremelling, G.; Herringer, S. N.; Turnbull, M. M.; Landee, C.; Kang, H.-J.; Schmidt, K. P.; Uhrig, G. S.; Chan, H. B.; Broholm, C.; Takano, Y.

    2013-03-01

    We report a comprehensive study of a strong-leg spin-1/2 ladder compound (C7H10N)2CuBr4 (DIMPY) by specific heat, magnetocaloric effect, magnetization and inelastic neutron scattering measurements. DIMPY is shown to be a perfect one-dimensional Heisenberg antiferromagnet with a spin gap =0.32 meV. Above a critical field Hc and at temperature below 1 K, the specific heat exhibits asymptotic linear-T behavior, characteristic of a Tomonaga-Luttinger liquid (TLL). In this field and temperature region, the specific heat in conjunction with the susceptibility yields the Wilson ratio RW. The result supports the relation RW = 4 K, where K is the TLL parameter. The work at ORNL was partially supported by the Division of Scientific User Facilities, Office of BES, DOE.

  8. Power-law behavior in electron transport through a quantum dot with Luttinger liquid leads

    NASA Astrophysics Data System (ADS)

    Yang, Kai-Hua; He, Xian; Wang, Huai-Yu; Liu, Kai-Di; Liu, Bei-Yun

    2014-08-01

    The electron transport of a system consisting of a Kondo dot and two Luttinger liquid (LL) leads is theoretically studied by use of nonequilibrium Green function approach. In the Kondo regime, the zero bias anomaly appears and the density of states of the dot obeys a power-law scaling at positive energy part with an exponent ?/2 = 1/ g - 1, where g reflects the electron interaction in the LL leads. The differential conductance shows a power-law scaling both in bias voltage and in temperature, with the exponent being ?. The power-law temperature dependence of the peak conductance is observed in different temperature regimes. These features are ascribed to the LL correlation in the leads. Our work describes both the zero bias anomaly and power-law scalings within one theoretical frame.

  9. Surface Tomonaga-Luttinger-Liquid State on Bi/InSb(001).

    PubMed

    Ohtsubo, Yoshiyuki; Kishi, Jun-Ichiro; Hagiwara, Kenta; Le Fèvre, Patrick; Bertran, François; Taleb-Ibrahimi, Amina; Yamane, Hiroyuki; Ideta, Shin-Ichiro; Matsunami, Masaharu; Tanaka, Kiyohisa; Kimura, Shin-Ichi

    2015-12-18

    A 1D metallic surface state was created on an anisotropic InSb(001) surface covered with Bi. Angle-resolved photoelectron spectroscopy (ARPES) showed a 1D Fermi contour with almost no 2D distortion. Close to the Fermi level (E_{F}), the angle-integrated photoelectron spectra showed power-law scaling with the binding energy and temperature. The ARPES plot above E_{F}, obtained thanks to a thermally broadened Fermi edge at room temperature, showed a 1D state with continuous metallic dispersion across E_{F} and power-law intensity suppression around E_{F}. These results strongly suggest a Tomonaga-Luttinger liquid on the Bi/InSb(001) surface. PMID:26722934

  10. 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.

  11. Fractionalization beyond Luttinger Liquid in the spectroscopy of Lithium Purple Bronze

    NASA Astrophysics Data System (ADS)

    Natalia, Lera; Jose, Alvarez

    We offer an interpretation for the departures of ARPES and STS spectroscopies experiments in quasi-one-dimensional Lithium Purple Bronze (LiPB) from single-band Luttinger Liquid (LL) theory. We base our calculation on a phenomenological description of the published data proposed in the original experiments and consider two bands crossing the Fermi level. We discuss the breakdown of the LL scaling relation η = α - 1 , the separation of the spinon edge and the holon peak, the phenomenological TL fit to the Energy Distribution Curves (EDC) and the survival of power-like density of states down to 4K. We consider non-critical fluctuations in one of the separated modes in which the electron fractionalize, and discuss under which conditions could be related with the upturn in the resistivity at 20-30K. We discuss the possibility of a gap in such separated mode and its role on the robust one-dimensional behavior. The connection with the proposed triplet superconductivity is at T = 1 . 4 K is also studied. We acknowledge financial support from MINECO FIS2012-37549-C05-03.

  12. Long-lived non-equilibrium states in a quantum-Hall Tomonaga-Luttinger liquid

    NASA Astrophysics Data System (ADS)

    Fujisawa, Toshimasa; Washio, Kazuhisa; Nakazawa, Ryo; Hashisaka, Masayuki; Muraki, Koji; Tokura, Yasuhiro

    The existence of long-lived non-equilibrium states without showing thermalization, which has previously been demonstrated in time evolution of ultracold atoms (quantum quench), suggests the possibility of their spatial analogue in transport behavior of interacting electrons in solid-state systems. Here we report long-lived non-equilibrium states in one-dimensional edge channels in the integer quantum Hall regime. For this purpose, non-trivial binary spectrum composed of hot and cold carriers is prepared by an indirect heating scheme using weakly coupled counterpropagating edge channels in an AlGaAs/GaAs heterostructure. Quantum dot spectroscopy clearly reveals that the carriers with the non-trivial binary spectrum propagate over a long distance (5 - 10 um), much longer than the length required for electronic relaxation (about 0.1 um), without thermalization into a trivial Fermi distribution. This observation is consistent with the integrable model of Tomonaga-Luttinger liquid. The long-lived spectrum implies that the system is well described by non-interacting plasmons, which are attractive for carrying information for a long distance. This work was supported by the JSPS 26247051 and 15H05854, and Nanotechnology Platform Program of MEXT.

  13. 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.

  14. Phases of one-dimensional SU(N) cold atomic Fermi gases-From molecular Luttinger liquids to topological phases

    NASA Astrophysics Data System (ADS)

    Capponi, S.; Lecheminant, P.; Totsuka, K.

    2016-04-01

    Alkaline-earth and ytterbium cold atomic gases make it possible to simulate SU(N)-symmetric fermionic systems in a very controlled fashion. Such a high symmetry is expected to give rise to a variety of novel phenomena ranging from molecular Luttinger liquids to (symmetry-protected) topological phases. We review some of the phases that can be stabilized in a one dimensional lattice. The physics of this multi-component Fermi gas turns out to be much richer and more exotic than in the standard SU(2) case. For N > 2, the phase diagram is quite rich already in the case of the single-band model, including a molecular Luttinger liquid (with dominant superfluid instability in the N-particle channel) for incommensurate fillings, as well as various Mott-insulating phases occurring at commensurate fillings. Particular attention will be paid to the cases with additional orbital degree of freedom (which is accessible experimentally either by taking into account two atomic states or by putting atoms in the p-band levels). We introduce two microscopic models which are relevant for these cases and discuss their symmetries and strong coupling limits. More intriguing phase diagrams are then presented including, for instance, symmetry protected topological phases characterized by non-trivial edge states.

  15. Dynamic structure factor of Luttinger liquids with quadratic energy dispersion and long-range interactions

    NASA Astrophysics Data System (ADS)

    Pirooznia, Peyman; Schütz, Florian; Kopietz, Peter

    2008-08-01

    We calculate the dynamic structure factor S(ω,q) of spinless fermions in one dimension with quadratic energy dispersion k2/2m and long-range density-density interaction whose Fourier transform fq is dominated by small momentum transfers q≲q0≪kF . Here q0 is a momentum-transfer cutoff and kF is the Fermi momentum. Using functional bosonization and the known properties of symmetrized closed fermion loops, we obtain an expansion of the inverse irreducible polarization to second order in the small parameter q0/kF . In contrast to perturbation theory based on conventional bosonization, our functional bosonization approach is not plagued by mass-shell singularities. For interactions which can be expanded as fq=f0+f0″q2/2+O(q4) with f0″≠0 , we show that the momentum scale qc=1/|mf0″| separates two regimes characterized by a different q dependence of the width γq of the collective zero sound mode and other features of S(ω,q) . For qc≪q≪kF we find that the line shape is non-Lorentzian with an overall width γq∝q3/(mqc) and a threshold singularity [(ω-ωq-)ln2(ω-ωq-)]-1 at the lower edge ω→ωq-=vq-γq , where v is the velocity of the zero sound mode. Assuming that higher orders in perturbation theory transform the logarithmic singularity into an algebraic one, we find for the corresponding threshold exponent μq=1-2ηq with ηq∝qc2/q2 . Although for q≲qc we have not succeeded to explicitly evaluate our functional bosonization result for S(ω,q) , we argue that for any one-dimensional model belonging to the Luttinger liquid universality class, the width of the zero sound mode scales as q2/m for q→0 .

  16. 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.

  17. 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.

  18. Phonon-Modulated Magnetic Interactions and Spin Tomonaga-Luttinger Liquid in the p -Orbital Antiferromagnet CsO2

    NASA Astrophysics Data System (ADS)

    Klanjšek, M.; Arčon, D.; Sans, A.; Adler, P.; Jansen, M.; Felser, C.

    2015-07-01

    The magnetic response of antiferromagnetic CsO2 , coming from the p -orbital S =1 /2 spins of anionic O2- molecules, is followed by 133Cs nuclear magnetic resonance across the structural phase transition occurring at Ts 1=61 K on cooling. Above Ts 1 , where spins form a square magnetic lattice, we observe a huge, nonmonotonic temperature dependence of the exchange coupling originating from thermal librations of O2- molecules. Below Ts 1 , where antiferromagnetic spin chains are formed as a result of p -orbital ordering, we observe a spin Tomonaga-Luttinger-liquid behavior of spin dynamics. These two interesting phenomena, which provide rare simple manifestations of the coupling between spin, lattice, and orbital degrees of freedom, establish CsO2 as a model system for molecular solids.

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

    PubMed

    Balram, Ajit C; Tőke, Csaba; Jain, J K

    2015-10-30

    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 ν and 1-ν 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. PMID:26565489

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

    NASA Astrophysics Data System (ADS)

    Balram, Ajit C.; Tőke, 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 ν and 1 -ν 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.

  1. Instability of three-band Luttinger liquids: renormalization group analysis and possible application to K2Cr3As3

    NASA Astrophysics Data System (ADS)

    Miao, Jian-Jian; Zhang, Fu-Chun; Zhou, Yi

    Motivated by recently discovered quasi-one-dimensional superconductor K2Cr3As3 with D3 h lattice symmetry, we study one-dimensional three-orbital Hubbard models with generic electron repulsive interaction described by intra-orbital repulsion U, inter-orbital repulsionU', and Hund's coupling J. As extracted from density functional theory calculation, two of the three atomic orbitals are degenerate and the third one is non-degenerate, and the system is presumed to be at incommensurate filling. With the help of bosonization, we have usual three-band Luttinger liquids in the normal state. Possible charge density wave (CDW), spin density wave (SDW) and superconducting instabilities are analyzed by one-loop renormalization group. The ground state depends on the ratio J / U . For the physical relevant parameter region, 0 < J / U < 1 / 2 , the ground states are superconducting states. When 0 < J / U < 1 / 3 , spin singlet superconducting state is favored. While spin triplet superconductor will be favored when 1 / 3 < J / U < 1 / 2 . The spin density wave state can be achieved only in the unphysical parameter region J / U > 1 / 2 .

  2. Quantum Phase Transition Between a Luttinger Liquid and a Gas of Cold Molecules

    SciTech Connect

    Law, K. T.; Feldman, D. E.

    2008-08-29

    We consider cold polar molecules confined in a helical optical lattice similar to those used in holographic microfabrication. An external electric field polarizes molecules along the axis of the helix. The large-distance intermolecular dipolar interaction is attractive but the short-scale interaction is repulsive due to geometric constraints and thus prevents collapse. The interaction strength depends on the electric field. We show that a zero-temperature second-order liquid-gas transition occurs at a critical field. It can be observed under experimentally accessible conditions.

  3. 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)

  4. Enhanced NMR relaxation of Tomonaga-Luttinger liquids and the magnitude of the carbon hyperfine coupling in single-wall carbon nanotubes.

    PubMed

    Kiss, A; Pályi, A; Ihara, Y; Wzietek, P; Simon, P; Alloul, H; Zólyomi, V; Koltai, J; Kürti, J; Dóra, B; Simon, F

    2011-10-28

    Recent transport measurements [Churchill et al. Nature Phys. 5, 321 (2009)] found a surprisingly large, 2-3 orders of magnitude larger than usual (13)C hyperfine coupling (HFC) in (13)C enriched single-wall carbon nanotubes. We formulate the theory of the nuclear relaxation time in the framework of the Tomonaga-Luttinger liquid theory to enable the determination of the HFC from recent data by Ihara et al. [Europhys. Lett. 90, 17,004 (2010)]. Though we find that 1/T(1) is orders of magnitude enhanced with respect to a Fermi-liquid behavior, the HFC has its usual, small value. Then, we reexamine the theoretical description used to extract the HFC from transport experiments and show that similar features could be obtained with HFC-independent system parameters. PMID:22107670

  5. 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,ω) 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.

  6. Metal-semiconductor transition and Luttinger-liquid behavior in quasi-one-dimensional BaVS3 studied by photoemission spectroscopy

    NASA Astrophysics Data System (ADS)

    Nakamura, M.; Sekiyama, A.; Namatame, H.; Fujimori, A.; Yoshihara, H.; Ohtani, T.; Misu, A.; Takano, M.

    1994-06-01

    The quasi-one-dimensional conductor BaVS3 exhibits successive phase transitions at ~240 K (linear chains to zigzag chains), ~70 K (metallic to semiconducting), and ~35 K (paramagnetic to antiferromagnetic). We have made high-resolution ultraviolet-photoemission-spectroscopy (UPS), x-ray-photoemission-spectroscopy, electrical-resistivity, and magnetic-susceptibility measurements on BaVS3. UPS spectra near the Fermi level of the metallic phase exhibit a power-law dependence on the electron binding energy, indicating that conduction electrons in BaVS3 behave as a Luttinger liquid. The power-law exponent is large (<~1), indicating that electron-electron interaction is long ranged and possibly that electron-phonon interaction is also important. The spectra exhibit gradual changes with temperature. In particular, a semiconducting gap starts to open well above the metal-to-semiconductor transition temperature and fully develops below it. We propose that the gradual orthorhombic distortion of the Jahn-Teller type below ~240 K lowers one of the d levels, dxy, and that below ~70 K electrons are fully transferred to the dxy band. The dxy band then becomes half-filled, resulting in the opening of a Mott-Hubbard gap.

  7. Enhancement of tunneling density of states at a Y junction of spin-1/2 Tomonaga-Luttinger liquid wires

    NASA Astrophysics Data System (ADS)

    Mardanya, Sougata; Agarwal, Amit

    2015-07-01

    We calculate the tunneling density of states (TDOS) in a dissipationless three-wire junction of interacting spin-1/2 electrons, and find an anomalous enhancement of the TDOS in the zero-bias limit, even for repulsive interactions for several bosonic fixed points. This enhancement is physically related to the reflection of holes from the junction for incident electrons, and it occurs only in the vicinity of the junction (x excitations and ω is the bias frequency), crossing over to the bulk value, which is always suppressed at larger distances. The TDOS exponent can be directly probed in an STM experiment by measuring the differential tunneling conductance as a function of either the bias voltage or temperature as done in C. Blumenstein et al., Nat. Phys. 7, 776 (2011), 10.1038/nphys2051.

  8. Excitations in the chiral spin liquid

    NASA Astrophysics Data System (ADS)

    Schroeter, Darrell

    2009-03-01

    Recently, a spin-Hamiltonian was presented [Schroeter et al, Phys. Rev. Lett. 99, 097202 (2007)] for which the chiral spin liquid is the exact ground state. This poster will present a numerical study of the excitations of the model, including results obtained by exact diagonalization of the model on 16 and 25-site lattices.

  9. Liquid storage tanks under vertical excitation

    SciTech Connect

    Philippacopoulos, A.J.

    1985-01-01

    Until recently, the hydrodynamic effects on liquid storage tanks induced by an earthquake excitation were basically treated for the horizontal component of the earthquake. Recent studies, however, showed that the hydrodynamic effects due to the vertical component of an earthquake may be significant. In these studies the tank is assumed to be fixed at the bottom. This paper is concerned with the hydrodynamic behavior of liquid storage tanks induced by vertical earthquake input excitation. First, the fluid-tank system is treated as a fixed-base system and a simple formula is obtained for the coupled fluid-structure natural frequency. Second, additional interaction effects due to the foundation flexibility on the fluid-tank system are investigated. It is concluded that the foundation flexibility may have a significant effect on the hydrodynamic behavior of the liquid storage tanks under a vertical ground shaking.

  10. Tomonaga-Luttinger physics in electronic quantum circuits.

    PubMed

    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

  11. 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.

  12. 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.

    PubMed

    Hermes, Matthew R; Hirata, So

    2015-09-14

    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. PMID:26374011

  13. Violent liquid sloshing in vertically excited cylindrical containers

    NASA Astrophysics Data System (ADS)

    Hashimoto, Hiroyuki; Sudo, Seiichi

    1988-04-01

    The frequency characteristics of gas-liquid surface sloshing induced by the vertical vibration of cylindrical containers containing liquid were experimentally investigated using a vibration-testing system with an electrodynamic shaker. The results show that the resonance frequency of the liquid-container vibration system depends on the excitation acceleration, and that the acceleration distribution of the container wall was not axisymmetrical at higher excitation accelerations. Significant changes in liquid pressure, container wall acceleration, and amplitude of surface oscillation were noted following the formation of a bubble cluster.

  14. Minimal excitation states of electrons in one-dimensional wires.

    PubMed

    Keeling, J; Klich, I; Levitov, L S

    2006-09-15

    A strategy is proposed to excite particles from a Fermi sea in a noise-free fashion by electromagnetic pulses with realistic parameters. We show that by using quantized pulses of simple form one can suppress the particle-hole pairs which are created by a generic excitation. The resulting many-body states are characterized by one or several particles excited above the Fermi surface accompanied by no disturbance below it. These excitations carry charge which is integer for noninteracting electron gas and fractional for Luttinger liquid. The operator algebra describing these excitations is derived, and a method of their detection which relies on noise measurement is proposed. PMID:17025911

  15. Liquid-Arc/Spark-Excitation Atomic-Emission Spectroscopy

    NASA Technical Reports Server (NTRS)

    Schlagen, Kenneth J.

    1992-01-01

    Constituents of solutions identified in situ. Liquid-arc/spark-excitation atomic-emission spectroscopy (LAES) is experimental variant of atomic-emission spectroscopy in which electric arc or spark established in liquid and spectrum of light from arc or spark analyzed to identify chemical elements in liquid. Observations encourage development of LAES equipment for online monitoring of process streams in such industries as metal plating, electronics, and steel, and for online monitoring of streams affecting environment.

  16. 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.

  17. Mixing of molecular excitation in a uniaxial liquid crystal

    SciTech Connect

    Aver`yanov, E.M.

    1995-07-01

    The influence of the mixing of molecular excitations due to local-field effects on the dielectric and spectral properties of uniaxial liquid crystals is investigated. The general properties of the spectrum of transverse optical excitations of the medium, viz, the sum rules for the oscillator strengths, frequencies, and damping constants of the dielectric function resonances, are established. The restricted applicability of the idea of a back ground polarizability (dielectric function) in the analysis of the mixing of molecular excitations is demonstrated. Mixing is taken into account in deriving new dispersion formulas for the imaginary and real parts of the dielectric tensor, which differ significantly from those used in the literature. A range of applicability has been established for the latter. Qualitative and quantitative interpretations of controversial experimental data for an extensive list of objects are given. The occurrence of mixing of dipole-active molecular vibrations, whose intensity has been found to be strongest for polyphilic objects that form nonchiral ferroelectric phases, has been demonstrated for molecular liquids and uniaxial liquid crystals from various chemical classes for the first time. The mixing of molecular excitations is considered as a possible mechanism for {open_quotes}polarization catastrophe{close_quotes} in liquid crystals having a soft mode in hthespectrum of transverse optical modes of vibration for the high-temperature phase. 53 refs., 1 fig.

  18. High fidelity simulation of liquid jet in an excited crossflow

    NASA Astrophysics Data System (ADS)

    Li, Xiaoyi; Soteriou, Marios

    2015-11-01

    Dynamic excitation of liquid jet in crossflow by externally oscillating the air stream has attracted much attention mainly due to its relevance to thermoacoustic instability mitigation. In this work, first principle high fidelity simulations of liquid jet atomization in an excited gaseous crossflow are performed using a dual-fluid Combined Level-Set and Volume Of Fluid (CLSVOF) interface capturing approach enhanced by a ghost fluid sharp interface treatment. Adaptive mesh refinement and Lagrangian algorithm for the smallest, spherical droplets are used to reduce the simulation cost. The simulations are validated against recently published experimental results. Mean features such as average jet penetration, volume flux and droplet size distribution and dynamic evolution of these quantities are studied. Proper Orthogonal Decomposition (POD) analyses of liquid surface features as well as detailed visualizations of the gaseous flow in the vicinity of the liquid column are performed. Detailed discussion of the impact of excitation on the physics of atomization is presented and the mechanisms by which excitation modifies the spray are identified.

  19. 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.

  20. Damping of zero sound in Luttinger liquids

    NASA Astrophysics Data System (ADS)

    Pirooznia, P.; Kopietz, P.

    2007-08-01

    We calculate the damping γq of collective density oscillations (zero sound) in a one-dimensional Fermi gas with dimensionless forward scattering interaction F and quadratic energy dispersion k2 / 2 m at zero temperature. Using standard many-body perturbation theory, we obtain γq from the expansion of the inverse irreducible polarization to first order in the effective screened (RPA) interaction. For wave-vectors | q| /kF ≪F (where kF = m vF is the Fermi wave-vector) we find to leading order γq ∝| q |3 /(vF m2). On the other hand, for F ≪| q| /kF most of the spectral weight is carried by the particle-hole continuum, which is distributed over a frequency interval of the order of q2/m. We also show that zero sound damping leads to a finite maximum proportional to |k - kF | -2 + 2 η of the charge peak in the single-particle spectral function, where η is the anomalous dimension. Our prediction agrees with photoemission data for the blue bronze K0.3MoO3. We comment on other recent calculations of γq.

  1. Nonlinear terahertz coherent excitation of vibrational modes of liquids

    NASA Astrophysics Data System (ADS)

    Allodi, Marco A.; Finneran, Ian A.; Blake, Geoffrey A.

    2015-12-01

    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.

  2. Nonlinear terahertz coherent excitation of vibrational modes of liquids.

    PubMed

    Allodi, Marco A; Finneran, Ian A; Blake, Geoffrey A

    2015-12-21

    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. PMID:26696055

  3. 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.

  4. Collective excitations in liquid and glassy 3-methylpentane

    NASA Astrophysics Data System (ADS)

    Benassi, Paola; Nardone, Michele; Giugni, Andrea; Baldi, Giacomo; Fontana, Aldo

    2015-09-01

    We present a detailed investigation of the terahertz vibrational dynamics of 3-methylpentane performed by means of high-resolution inelastic x-ray scattering (IXS). We probe the dynamics in a large temperature range, which includes the glass, the supercooled liquid, and the liquid phases. The characteristic frequency of the excitations follows a well-defined dispersion curve extending beyond 8 nm-1 at all the investigated temperatures, indicating the persistence of a solidlike behavior also in the liquid phase. This implies the existence of a pseudo-Brillouin zone whose size compares surprisingly well with the periodicity inferred from the first sharp diffraction peak in the static structure factor. We show that, in the investigated temperature range, both sizes undergo a variation of about 15%-20%, comparable to that of the average intermolecular distance. We finally show that the IXS sound velocity coincides with the infinite frequency sound velocity previously inferred from visible and ultraviolet Brillouin spectroscopy data. This analysis confirms the role of the shear relaxation processes in determining the variation with frequency of the apparent sound velocity.

  5. Optic-like excitations in binary liquids: transverse dynamics

    NASA Astrophysics Data System (ADS)

    Bryk, Taras; Mryglod, Ihor

    2000-07-01

    The generalized collective mode approach is applied for the study of transverse dynamics in binary mixtures. The scheme is based on simultaneous treatment of the conserved total mass current and the mutual mass-concentration currents, as well as their time derivatives. The condition for existence of optic-like transverse modes in a binary system is derived. It is shown that high mutual diffusion and a tendency towards demixing prevent the emergence of transverse optic-like modes. Optic-like excitations are found in a Lennard-Jones Kr-Ar fluid and the liquid-metallic alloys Mg70Zn30 and Li4Pb, while in the `fast-sound' dense gas mixture He75Ar25 they do not appear for small wavenumbers.

  6. On the Kohn-Luttinger conundrum

    NASA Astrophysics Data System (ADS)

    Hirata, So; He, Xiao

    2013-05-01

    Kohn and Luttinger [Phys. Rev. 118, 41 (1960)], 10.1103/PhysRev.118.41 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.

  7. 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.

  8. 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.

  9. Contrasting Behaviours of AC and DC Excited Plasmas in Contact with Liquid

    NASA Astrophysics Data System (ADS)

    Liu, Jingjing; Hu, Xiao

    2013-08-01

    A comparative study of the needle-to-liquid plasma in the continuous mode with DC and AC excitations is detailed in this paper. All plasmas studied here are shown to be glow discharges. This study is based on measurements of several key parameters, including electrical energy, optical emission intensities of active species, rotational and vibrational temperatures, and temperatures of the needle and liquid electrodes. AC plasmas can produce 1.2~5 times higher excited state active species than DC plasmas under the same dissipated power. AC excited liquid plasmas have the highest energy utilization efficiency among the three systems (AC excited plasmas, DC excited plasmas with water anode and DC excited plasmas with water cathode); most of the energy is used to produce useful species rather than to heat the electrodes and plasmas.

  10. A numerical study of liquid sloshing in a two-dimensional tank under external excitations

    NASA Astrophysics Data System (ADS)

    Hou, Ling; Li, Fangcheng; Wu, Chunliang

    2012-09-01

    In this research, liquid sloshing behavior in a 2-D rectangular tank was simulated using ANSYS-FLUENT software subject to single or multiple-coupled external excitations (such as sway coupled with roll, and sway and roll coupled with heave). The volume of fluid (VOF) method was used to track the free surface of sloshing. External excitation was imposed through the motion of the tank by using the dynamic mesh technique. The study shows that if the tank is subjected to multiple coupled excitations and resonant excitation frequencies, liquid sloshing will become violent and sloshing loads, including impact on the top wall, will be intensified.

  11. 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.

  12. 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.

  13. Experimental study on chaos of a liquid-filled tank under vertical excitation

    SciTech Connect

    Okazaki, K.; Watanabe, K.; Tani, J.

    1995-11-01

    This paper is concerned with an experimental study on the chaos of a partially liquid-filled cylindrical tank under vertical excitation. The test cylinder made of polyester film was harmonically excited with constant displacement amplitude. It has been well known that the partially liquid-filled cylindrical tank under periodic vertical excitation gives rise to the parametoric resonance. As the excitation amplitude increases, the nonlinear response characteristics of soft and hard spring types as well as chaos were found to appear in this system. The occurrence of chaos was recognized by the time history, Poincare map, phase trajectory, and power spectrum. Furthermore, the sloshing and chaotic motion of the liquid surface were found to appear in the lower frequency range than the parametric resonance and chaotic motion of the cylindrical shell wall.

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

    SciTech Connect

    Tang, Y.

    1995-01-01

    A study on the sloshing response of nonuniform density liquid in a tank undergoing lateral base excitations is presented. 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.

  15. Impulsive response of nonuniform density liquid in a laterally excited tank

    SciTech Connect

    Tang, Y.; Chang, Y.W.

    1994-04-01

    A study on the impulsive component of the dynamic response of a liquid of nonuniform density in a tank undergoing lateral base excitations is presented. The system considered is a circular cylindrical tank containing an incompressible and inviscid liquid whose density increases with the liquid depth. The density distribution along the depth can be of any arbitrary continuous or discontinuous function. In the analysis, the liquid field is divided into n layers. The thickness of the liquid layers can be different, but the density of each liquid layer is considered to be uniform and is equal to the value of the original liquid density at the mid-height of that layer. The problem is solved by the eigenfunction expansion in conjunction with the transfer matrix technique. The effect of the nonuniform liquid density on the impulsive component of the dynamic response is illustrated in a numerical example in which the linear and cosine distributions of the liquid density are assumed. The response quantities examined include the impulsive pressure, base shear and moments. The results are presented in tabular and graphical forms. It is found that the impulsive pressure distribution along the tank wall is not sensitive to the detailed distribution function of the density, and the base shear and moments for the nonuniform liquid can be estimated by assuming an equivalent uniform liquid density that preserves the total liquid weight. The effect of tank flexibility is assessed by a simple approach in which the response quantities for flexible tanks are evaluated by simplified equations.

  16. Impulsive response of nonuniform density liquid in a laterally excited tank

    NASA Astrophysics Data System (ADS)

    Tang, Y.; Chang, Y. W.

    1994-04-01

    A study on the impulsive component of the dynamic response of a liquid of nonuniform density in a tank undergoing lateral base excitations is presented. The system considered is a circular cylindrical tank containing an incompressible and inviscid liquid whose density increases with the liquid depth. The density distribution along the depth can be of any arbitrary continuous or discontinuous function. In the analysis, the liquid field is divided into n layers. The thickness of the liquid layers can be different, but the density of each liquid layer is considered to be uniform and is equal to the value of the original liquid density at the mid-height of that layer. The problem is solved by the eigenfunction expansion in conjunction with the transfer matrix technique. The effect of the nonuniform liquid density on the impulsive component of the dynamic response is illustrated in a numerical example in which the linear and cosine distributions of the liquid density are assumed. The response quantities examined include the impulsive pressure, base shear, and moments. The results are presented in tabular and graphical forms. It is found that the impulsive pressure distribution along the tank wall is not sensitive to the detailed distribution function of the density, and the base shear and moments for the nonuniform liquid can be estimated by assuming an equivalent uniform liquid density that preserves the total liquid weight. The effect of tank flexibility is assessed by a simple approach in which the response quantities for flexible tanks are evaluated by simplified equations.

  17. Liquid to vapor phase transition in excited nuclei.

    PubMed

    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

    2002-01-28

    The thermal component of the 8 GeV/c pi+ Au data of the ISiS Collaboration is shown to follow the scaling predicted by Fisher's model when Coulomb energy is taken into account. Critical exponents tau and sigma, the critical point (p(c),rho(c),T(c)), surface energy coefficient c(0), enthalpy of evaporation DeltaH, and critical compressibility factor C(F)(c) are determined. For the first time, the experimental phase diagrams, (p,T) and (T,rho), describing the liquid vapor coexistence of finite neutral nuclear matter have been constructed. PMID:11801117

  18. Collective excitations in liquid CD4: Neutron scattering and molecular-dynamics simulations

    NASA Astrophysics Data System (ADS)

    Guarini, E.; Bafile, U.; Barocchi, F.; Demmel, F.; Formisano, F.; Sampoli, M.; Venturi, G.

    2005-12-01

    We have investigated the dynamic structure factor S(Q,?) of liquid CD4 at T = 97.7 K in the wave vector range 2 <= Q/nm-1 <= 15 by means of neutron scattering and molecular-dynamics simulation, in order to study the centre-of-mass collective dynamics. The agreement between the experimental spectra and those simulated using a recent ab initio based intermolecular potential is good, particularly at low Q. Underdamped collective excitations, detected in the whole experimental Q-range, characterize the dynamics of liquid CD4 as markedly different from that of other molecular liquids. Also, the energy and damping of collective excitations in methane are shown to differ considerably, even at the lowest measured Q-values, from those of linearized hydrodynamic modes. An empirical relation, able to reconcile the different wave vector ranges of mode propagation observed in disparate liquids, is investigated.

  19. Spectral function of the Tomonaga-Luttinger model revisited: Power laws and universality

    NASA Astrophysics Data System (ADS)

    Markhof, L.; Meden, V.

    2016-02-01

    We reinvestigate the momentum-resolved single-particle spectral function of the Tomonaga-Luttinger model. In particular, we focus on the role of the momentum dependence of the two-particle interaction V (q ) . Usually, V (q ) is assumed to be a constant and integrals are regularized in the ultraviolet "by hand" employing an ad hoc procedure. As the momentum dependence of the interaction is irrelevant in the renormalization group sense, this does not affect the universal low-energy properties of the model, e.g., exponents of power laws, if all energy scales are sent to zero. If, however, the momentum k is fixed away from the Fermi momentum kF, with |k - kF| setting a nonvanishing energy scale, the details of V (q ) start to matter. We provide strong evidence that any curvature of the two-particle interaction at small transferred momentum q destroys power-law scaling of the momentum-resolved spectral function as a function of energy. Even for |k - kF| much smaller than the momentum-space range of the interaction the spectral line shape depends on the details of V (q ) . The significance of our results for universality in the Luttinger liquid sense, for experiments on quasi-one-dimensional metals, and for recent results on the spectral function of one-dimensional correlated systems taking effects of the curvature of the single-particle dispersion into account ("nonlinear LL phenomenology") is discussed.

  20. 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.}

  1. 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.

  2. 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.

  3. 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).

  4. Nature of the many-body excitations in a quantum wire: Theory and experiment

    NASA Astrophysics Data System (ADS)

    Tsyplyatyev, O.; Schofield, A. J.; Jin, Y.; Moreno, M.; Tan, W. K.; Anirban, A. S.; Ford, C. J. B.; Griffiths, J. P.; Farrer, I.; Jones, G. A. C.; Ritchie, D. A.

    2016-02-01

    The natural excitations of an interacting one-dimensional system at low energy are the hydrodynamic modes of a Luttinger liquid, protected by the Lorentz invariance of the linear dispersion. We show that beyond low energies, where the quadratic dispersion reduces the symmetry to Galilean, the main character of the many-body excitations changes into a hierarchy: calculations of dynamic correlation functions for fermions (without spin) show that the spectral weights of the excitations are proportional to powers of R2/L2 , where R is a length-scale related to interactions and L is the system length. Thus only small numbers of excitations carry the principal spectral power in representative regions on the energy-momentum planes. We have analyzed the spectral function in detail and have shown that the first-level (strongest) excitations form a mode with parabolic dispersion, like that of a renormalized single particle. The second-level excitations produce a singular power-law line shape to the first-level mode and multiple power laws at the spectral edge. We have illustrated a crossover to a Luttinger liquid at low energy by calculating the local density of states through all energy scales: from linear to nonlinear, and to above the chemical potential energies. In order to test this model, we have carried out experiments to measure the momentum-resolved tunneling of electrons (fermions with spin) from/to a wire formed within a GaAs heterostructure. We observe a well-resolved spin-charge separation at low energy with appreciable interaction strength and only a parabolic dispersion of the first-level mode at higher energies. We find a structure resembling the second-level excitations, which dies away rapidly at high momentum in line with the theoretical predictions here.

  5. 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.

  6. 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

  7. 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.

  8. Tomonaga-Luttinger liquid theory for metallic fullurene polymers

    NASA Astrophysics Data System (ADS)

    Yoshioka, Hideo; Shima, Hiroyuki; Noda, Yusuke; Ono, Shota; Ohno, Kaoru

    2016-04-01

    We investigate the low energy behavior of local density of states in metallic C60 polymers theoretically. The multichannel bosonization method is applied to electronic band structures evaluated from first-principles calculation, by which the effects of electronic correlation and nanoscale corrugation in the atomic configuration are fully taken into account. We obtain a closed-form expression for the power-law anomalies in the local density of states, which successfully describes the experimental observation on the C60 polymers in a quantitative manner. An important implication from the closed-form solution is the existence of an experimentally unobserved crossover at nearly a hundred milli-electron volts, beyond which the power-law exponent of the C60 polymers should change significantly.

  9. BCS coupling in a 1D Luttinger liquid

    NASA Astrophysics Data System (ADS)

    Eneias, R.; Ferraz, A.

    2015-12-01

    In this work we investigate the effect produced by the BCS coupling in spinless fermions in one spatial dimension. Using bosonization techniques our initial model is rewritten in terms of a sine-Gordon field and a free massless scalar field. As a result the Cooper pair in our scenario is made up of soliton and antisoliton particles. We calculate the single particle Green’s function, the pair correlation function and the optical conductivity associated with the physical fermions and we show how they differ from their conventional quasiparticle analogues. Finally, we compare our results with related experimental findings for high temperature superconductors and we display how they fit qualitatively well the related observed effects produced by the anti-nodal quasiparticles in those materials.

  10. 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.

  11. Collective excitations in quantum Hall liquid crystals: Single-mode approximation calculations

    SciTech Connect

    Lapilli, Cintia M.; Wexler, Carlos

    2006-02-15

    A variety of recent experiments probing the low-temperature transport properties of quantum Hall systems have suggested an interpretation in terms of liquid crystalline mesophases dubbed quantum Hall liquid crystals. The single mode approximation (SMA) has been a useful tool for the determination of the excitation spectra of various systems such as phonons in {sup 4}He and in the fractional quantum Hall effect. In this paper we calculate (via the SMA) the spectrum of collective excitations in a quantum Hall liquid crystal by considering nematic, tetratic, and hexatic generalizations of Laughlin's trial wave function having twofold, fourfold, and sixfold broken rotational symmetry, respectively. In the limit of zero wave vector q the dispersion of these modes is singular, with a gap that is dependent on the direction along which q=0 is approached for nematic and tetratic liquid crystalline states, but remains regular in the hexatic state, as permitted by the fourth order wave-vector dependence of the (projected) oscillator strength and static structure factor.

  12. 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.

  13. Excitation of convective motions in isotropic and anisotropic liquids by light

    SciTech Connect

    Akopyan, R S; Alaverdyan, R B; Muradyan, L Kh; Seferyan, G E; Chilingaryan, Yu S

    2003-01-31

    The possibility of excitation of convective motions of the Rayleigh - Benard and Marangoni type in isotropic liquids and nematic liquid crystals upon absorption of light with a spatially periodic intensity distribution is demonstrated theoretically and experimentally. It is shown that gravitational and thermocapillary surface hydrodynamic waves are observed in the case of a running interference pattern. The possibility of control and the stability of convective motions are investigated. Benard cells become unstable when the light intensity is high. These instabilities are of thermal origin because the Prandtl number for the medium under investigation is considerably larger than unity. The competition between the gravitational and thermocapillary mechanisms of photohydrodynamic reorientation of the nematic liquid crystal director is also studied. The effect of convective motions on the thermodynamic phase transition is observed and explained. (interaction of laser radiation with matter)

  14. Nonvolatile liquid anthracenes for facile full-colour luminescence tuning at single blue-light excitation

    PubMed Central

    Babu, Sukumaran Santhosh; Hollamby, Martin J.; Aimi, Junko; Ozawa, Hiroaki; Saeki, Akinori; Seki, Shu; Kobayashi, Kenji; Hagiwara, Keita; Yoshizawa, Michito; Möhwald, Helmuth; Nakanishi, Takashi

    2013-01-01

    Nonvolatile room-temperature luminescent molecular liquids are a new generation of organic soft materials. They possess high stability, versatile optical properties, solvent-free fluid behaviour and can effectively accommodate dopant dye molecules. Here we introduce an approach to optimize anthracene-based liquid materials, focussing on enhanced stability, fluorescence quantum yield, colour tunability and processability, with a view to flexible electronic applications. Enveloping the anthracene core in low-viscosity branched aliphatic chains results in stable, nonvolatile, emissive liquid materials. Up to 96% efficient energy-transfer-assisted tunable emission is achieved by doping a minute amount of acceptor dye in the solvent-free state. Furthermore, we use a thermoresponsive dopant to impart thermally controllable luminescence colours. The introduced strategy leading to diverse luminescence colours at a single blue-light excitation can be an innovative replacement for currently used luminescent materials, providing useful continuous emissive layers in developing foldable devices. PMID:23736114

  15. Nonlinear Vibrations of Elastic Structures Containing a Cylindrical Liquid Tank under Vertical Excitation

    NASA Astrophysics Data System (ADS)

    Ikeda, Takashi; Murakami, Shin

    This study investigates the nonlinear vibrations of an elastic structure, with a liquid-filled cylindrical tank, which is subjected to a vertical sinusoidal excitation. This structure-tank system behaves as an autoparametric system. Modal equations governing the coupled motions of the structure and liquid sloshing are derived when the natural frequency of the structure is equal to twice the natural frequency of the first axisymmetric sloshing mode. Van der Pol's method is applied to the modal equations to determine the theoretical resonance curves. The theoretical results can be concluded as follows: (1) As the liquid level decreases, the resonance curve for the liquid sloshing changes from a soft spring type to a hard spring type. (2) The structure's resonance curve flattens out at small amplitude when the liquid level is appropriate. (3) Amplitude-modulated motions appear for the negative and positive values of the internal resonance ratio's deviation (the detuning parameter) in the high and low liquid levels, respectively. (4) Furthermore, the results of the bifurcation analysis, Poincaré maps and Lyapunov exponents reveal that amplitude-modulated motions and chaotic oscillations can occur in the system. In experiments, the theoretical resonance curves were quantitatively in agreement with the experimental data.

  16. Liquid sampling-atmospheric pressure glow discharge as a secondary excitation source: Assessment of plasma characteristics

    NASA Astrophysics Data System (ADS)

    Manard, Benjamin T.; Gonzalez, Jhanis J.; Sarkar, Arnab; Dong, Meirong; Chirinos, Jose; Mao, Xianglei; Russo, Richard E.; Marcus, R. Kenneth

    The liquid sampling-atmospheric pressure glow discharge (LS-APGD) has been assessed as a secondary excitation source with a parametric evaluation regarding carrier gas flow rate, applied current, and electrode distance. With this parametric evaluation, plasma optical emission was monitored in order to obtain a fundamental understanding with regards to rotational temperature (Trot), excitation temperature (Texc), electron number density (ne), and plasma robustness. Incentive for these studies is not only for a greater overall fundamental knowledge of the APGD, but also in instrumenting a secondary excitation/ionization source following laser ablation (LA). Rotational temperatures were determined through experimentally fitting of the N2 and OH molecular emission bands while atomic excitation temperatures were calculated using a Boltzmann distribution of He and Mg atomic lines. The rotational and excitation temperatures were determined to be ~ 1000 K and ~ 2700 K respectively. Electron number density was calculated to be on the order of ~ 3 1015 cm- 3 utilizing Stark broadening effects of the H? line of the Balmer series and a He I transition. In addition, those diagnostics were performed introducing magnesium (by solution feed and laser ablation) into the plasma in order to determine any perturbation under heavy matrix sampling. The so-called plasma robustness factor, derived by monitoring Mg II/Mg I emission ratios, is also employed as a reflection of potential perturbations in microplasma energetics across the various operation conditions and sample loadings. While truly a miniaturized source (< 1 mm3 volume), the LS-APGD is shown to be quite robust with plasma characteristics and temperatures being unaffected upon introduction of metal species, whether by liquid or laser ablation sample introduction.

  17. Evidence of delayed light emission of tetraphenyl-butadiene excited by liquid-argon scintillation light

    NASA Astrophysics Data System (ADS)

    Segreto, E.

    2015-03-01

    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, re-emits 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 clarifying the anomalies in liquid-argon scintillation light reported in the literature since the 1970s, 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, which emit scintillation photons with wavelengths shorter than 127 nm.

  18. Semiclassical Time Evolution of the Holes from Luttinger Hamiltonian

    SciTech Connect

    Jiang, Z.F.; Li, R.D.; Zhang, Shou-Cheng; Liu1, W.M.; /Beijing, Inst. Phys.

    2010-02-15

    We study the semi-classical motion of holes by exact numerical solution of the Luttinger model. The trajectories obtained for the heavy and light holes agree well with the higher order corrections to the abelian and the non-abelian adiabatic theories in Ref. [1] [S. Murakami et al., Science 301, 1378 (2003)], respectively. It is found that the hole trajectories contain rapid oscillations reminiscent of the 'Zitterbewegung' of relativistic electrons. We also comment on the non-conservation of helicity of the light holes.

  19. The Effects of a Magnetic Field on Parametric Excitation of Surface Waves in Liquid Gallium

    NASA Astrophysics Data System (ADS)

    Halcrow, Jonathan; Ji, Hantao

    2002-11-01

    The Liquid Metal Experiment (LMX) at the Princeton Plasma Physics Laboratory is designed to study magnetohydrodynamic (MHD) effects on driven waves in liquid gallium under the influence of a magnetic field. Previous work with LMX has measured the dispersion relation in the case of one-dimensional surface waves propagating in the directions perpendicular and parallel to the magnetic field. Damping was found only in the case of propagation parallel to the field(Fox, W. 2001. Magnetohydrodynamic Surface Waves in Liquid Metal). Senior Thesis, Princeton University.. Parametrically driven waves have been studied since the time of Faraday and in many types of media including granular, ferromagnetic, and colloidal(Rabinovich, M.I. et al. 2000. The Dynamics of Patterns.) World Scientific Publishing Co. Pte. Ltd. Singapore.. The goal of this work is to examine the case of parametric excitation of a liquid metal in the presence of a magnetic field parallel to the unperturbed surface. Various boundary conditions and orientations will be studied.

  20. Development of High-Throughput Liquid Treatment System using Slot Antenna Excited Microwave Plasma

    NASA Astrophysics Data System (ADS)

    Takitou, Sho; Ito, Michiko; Takashima, Seigou; Nomura, Norio; Kitagawa, Tominori; Toyoda, Hirotaka

    2015-09-01

    Recently, much attention has been given to plasma production under liquid and its industrial applications as well as investigation of chemical reactions as a result of plasma-liquid interactions. In various kinds of plasma production techniques, we have proposed pulsed microwave excited plasma using slot antenna, where damage to the slot electrode can be minimized and plasma volume can be increased. Furthermore, we have proposed an in-line microwave plasma system where plasma is efficiently produced under reduced pressures using Venturi effect, and have demonstrated enhancement of organic decomposition efficiency. For practical use of the plasma liquid treatment, however, cost-effective and more efficient treatment system with high treatment capability is required. In this study, we propose further enhancement of the treatment speed by designing four-parallel-type liquid treatment device where four discharges for the treatment are performed using one microwave power source. Decomposition speed of newly-developed plasma system is investigated. Not only high decomposition rate but also enhanced energy efficiency is realized.

  1. Watching molecules reorient in liquid crystal droplets with multiphoton-excited fluorescence microscopy

    NASA Astrophysics Data System (ADS)

    Higgins, Daniel A.; Luther, Brenda J.

    2003-08-01

    A new form of time-resolved multiphoton-excited fluorescence imaging is described and used to study electric-field-induced reorientation dynamics in polymer-dispersed liquid crystal (LC) films. This method provides information on the static and dynamic LC orientation via polarization-dependent three-photon excitation of the nematic ultraviolet chromophores in these materials. Static fluorescence images are obtained with ≈235 nm resolution in all three dimensions. In dynamics studies, the three-photon-excited fluorescence is recorded as a function of time and position over individual LC droplets, as an applied electric field is switched on and off. Time-resolved images with ≈235 nm spatial resolution and 200 μs time resolution are obtained. Movies depicting the local reorientation dynamics are prepared from these data and are presented for common ellipsoidal LC droplets and for novel toroidal droplets. The field-induced reorientation dynamics within the ellipsoidal droplets are shown to be more complex (i.e., spatially variable) than in the toroidal droplets. Dynamical complexity is concluded to arise from LC organizational complexity in the droplets. The bipolar configuration found in ellipsoidal droplets incorporates bend and splay deformations of the nematic phase and two disclination points. In contrast, toroidal droplets incorporate a simpler toroidal configuration in which only bend deformations occur.

  2. Localized Excitations and the Morphology of Cooperatively Rearranging Regions in a Colloidal Glass-Forming Liquid

    NASA Astrophysics Data System (ADS)

    Gokhale, Shreyas; Ganapathy, Rajesh; Nagamanasa, K. Hima; Sood, A. K.

    2016-02-01

    We develop a scheme based on a real space microscopic analysis of particle dynamics to ascertain the relevance of dynamical facilitation as a mechanism of structural relaxation in glass-forming liquids. By analyzing the spatial organization of localized excitations within clusters of mobile particles in a colloidal glass former and examining their partitioning into shell-like and corelike regions, we establish the existence of a crossover from a facilitation-dominated regime at low area fractions to a collective activated hopping-dominated one close to the glass transition. This crossover occurs in the vicinity of the area fraction at which the peak of the mobility transfer function exhibits a maximum and the morphology of cooperatively rearranging regions changes from stringlike to a compact form. Collectively, our findings suggest that dynamical facilitation is dominated by collective hopping close to the glass transition, thereby constituting a crucial step towards identifying the correct theoretical scenario for glass formation.

  3. Luttinger's approach to thermal transport in nanoscale conductors

    NASA Astrophysics Data System (ADS)

    Eich, F. G.; Principi, A.; di Ventra, M.; Vignale, G.

    2015-03-01

    The description of thermoelectric transport from first principles has recently attracted renewed interest due to its potential role in the development of sustainable energy sources. We will present our recent work comparing Luttinger's approach to thermal transport to the widely used Landauer-Büttiker formalism. We show that they coincide in the linear regime and highlight their differences in the nonlinear regime. Moreover, we discuss the asymptotic (steady state) and transient currents for a simple two-terminal setup. We will put these results in context with our recently proposed thermal Density-Functional Theory and discuss strategies to define a local temperature. We gratefully acknowledge support from DOE under Grant Nos. DE-FG02-05ER46203 and DE-FG02-05ER46204.

  4. Ultrafast spectroscopy of electron transfer dynamics in liquids; excitation transfer studies of phase transitions

    NASA Astrophysics Data System (ADS)

    Goun, Alexei A.

    The transfer of an electron from a donor to an acceptor is the fundamental step in a wide range of chemical and biological processes. As a result, electron-transfer reactions have been the focus of numerous theoretical and experimental efforts aimed at understanding the kinetics and mechanism of the transfer event. Liquid solvents are an important medium for electron-transfer processes. The influences of the distance dependence, diffusion, the radial distribution function, and the hydrodynamic effect have been incorporated into the theory of electron transfer in solution, as well as into the theory of electron transfer between donors and acceptors in the head group regions of micelles. The development of new laser system with a pulse duration of tens of femtoseconds, with tunable wavelength allowed us to study these processes on a considerably shorter time scale than previous studies. This allowed us to observe not only the diffusion controlled but also the kinetics of electron transfer for donor/acceptor pairs that are in close proximity. In one set of experiments we have studied the kinetics of electron transfer in electron accepting molecule (rhodamine 3B) dissolved in electron donating solvent (N,N-dimethylaniline). The data for the forward electron transfer and geminate recombination are approximated by the statistical theory of the electron transfer. Optical anisotropy observed in the experiment demonstrates the orientation dependence of the electron transfer rate. In further experiments we investigated the electron transfer in non-hydrogen bonding liquids of increasing viscosity. The effective value of the donor/acceptor electronic coupling was found to decrease with viscosity. Electron transfer experiments were also carried out on the surface of micelles. The systems studied are the hole donor octadecyl-rhodamine B (ODRB) and the hole acceptor N,N-dimethyl-aniline (DMA) in micelles made of dodecyltrimethylammonium bromide (DTAB) and tetradecyltrimethylammonium bromide (TTAB). It was found that the effective coupling is reduced compared to donor/acceptor pairs dissolved in simple liquids. In the 2nd half of thesis we have addressed the question of the dynamics of phase transitions. We have demonstrated the ability to use the fluorescent excitation-transfer technique to study the demixing of liquids specifically, kinetics of demixing water and 2,6-dimethylpyridine. These two liquids possess a low critical temperature point, which allowed us to use a temperature jump from a laser pulse to initiate the process of phase separation. It was found that Coumarin480 laser dye and HPTS (8-Hydroxypyrene-1,3,6-trisulfonic acid) fluorescent dye have significantly different solubilities in the components of the mixture. These dyes undergo excitation transfer from Coumarin480 to HPTS in the uniform state, but not in the phase-separated state. A system with a temperature jump pump and an excitation transfer probe measured the time scale of the initial step of the phase separation.

  5. Propagation of acoustic excitations in a liquid at large wavevectors: a molecular-dynamics study

    NASA Astrophysics Data System (ADS)

    Sampoli, Marco; Bafile, Ubaldo; Barocchi, Fabrizio; Guarini, Eleonora; Venturi, Giovanni

    2008-03-01

    A two-decade development of dedicated high-performance instrumentation at major neutron and synchrotron radiation sources has stimulated significant growth in the number and quality of spectroscopic studies of the collective dynamics of fluids, making Brillouin scattering, in its neutron and x-ray 'versions', a fast growing field of research. However, in contrast with the large amount of work done for wavevector Q lower than the position Qp of the main peak of the static structure factor S(Q), very little is known about the behaviour of acoustic excitations at much larger Q. We present molecular-dynamics simulation results for the translational part of the dynamic structure factor of the molecular liquid CD4 up to high Q values (Q~4Qp), analysed through the fitting of the viscoelastic model line shape. The analysis, carried out by applying the concepts described in a recent paper, shows that underdamped sound excitations persist at least up to such high Q values, in agreement with the existence of the distinct part of S(Q), with the exception of a restricted interval around Qp where the collective oscillations become overdamped.

  6. Investigating the role of vibrational excitation in simulating charged-particle tracks in liquid pyrimidine

    NASA Astrophysics Data System (ADS)

    Brunger, Michael J.; Ratnavelu, Kuru; Buckman, Stephen J.; Jones, Darryl B.; Muñoz, Antonio; Blanco, Francisco; García, Gustavo

    2016-03-01

    We report on our results of a study into the sensitivity of charged-particle (electron) track simulations in liquid pyrimidine, to the vibrational cross sections and vibrational energy loss distribution function employed in those simulations. We achieve this by repeating the earlier investigation of Fuss et al. [J. Appl. Phys. 117, 214701 (2015)], but now incorporating more accurate data for the vibrational integral cross sections and the energy loss distribution function that have recently become available. We find that while changes in absorbed dose or particle range are quite minor, due to the energy transferred via vibrational excitations being low in comparison to that for other processes such as ionisation, at the very end of the tracks, where non-ionizing interactions dominate, the significantly large numbers of vibrational excitation processes increases the electrons' ability to induce other effects (e.g. sample heating, bond breaking and radical formation) that might cause damage. Contribution to the Topical Issue "Advances in Positron and Electron Scattering", edited by Paulo Limao-Vieira, Gustavo Garcia, E. Krishnakumar, James Sullivan, Hajime Tanuma and Zoran Petrovic.

  7. Transient displacement currents generated by excited-state dipole moments in liquids

    SciTech Connect

    Smirnov, S.N.; Braun, C.L. )

    1994-02-17

    We consider the general form of the transient signals which arise in a dc conductivity cell when dipoles are photoinduced in a liquid solution by laser excitation. The formalism is based on the solution of Debye's equation for rotating molecules but includes a time-variable concentration of dipoles. Onsager's treatment of the internal field acting on the dipoles is used. It is shown that, given adequate time resolution, this method allows measurement of the rotational time, the lifetime, and the dipole moment of various excited states. When the ground state is dipolar, the signal is shown to depend on the polarization of the light with respect to the applied electric field. Variation of the light polarization in such an experiment increases the accuracy of derived parameters and even allows the ground state dipole moment to be measured. Results depend substantially on the shape of the dipolar species. An extension of Onsager's treatment to the case of an ellipsoidal cavity is applied to the problem. Approximations to the general result for an ellipsoidal cavity are also given. 12 refs., 8 figs.

  8. Thermally excited fluid flow in a microsized liquid crystal channel with a free surface

    NASA Astrophysics Data System (ADS)

    Zakharov, A. V.; Vakulenko, A. A.

    2015-06-01

    The temperature-induced reorientation dynamics in microsized liquid crystal (LC) channel with a free LC/vacuum interface has been investigated theoretically based on the hydrodynamic theory including the director motion, the thermally excited fluid flow v, and the temperature T redistribution, produced by induced heating in the interior of the LC sample. Analysis of the numerical results shows that due to interaction between ∇T and the gradient of the director field ∇ n ˆ in the LC channel bounded by the free LC/vacuum interface, a thermally excited vortical fluid flow is maintained in the vicinity of the heat source. Calculations also show that in the case of the fast heating, the LC sample settles down to three-vortical flow regime, whereas in the case of the slow heating, the LC material settles down to bi-vortical flow regime. As for nematogenic material, we have considered the LC channel to be occupied by 4-n-pentyl-4'-cyanobiphenyl and investigated the effect of both ∇ n ˆ and ∇T on the magnitude and direction of v, as well as on the height of the LC film on the solid surface, for a number of heating and hydrodynamic regimes.

  9. 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.

  10. 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.

  11. Topological Influence of Lyotropic Liquid Crystalline Systems on Excited-State Proton Transfer Dynamics.

    PubMed

    Roy, Bibhisan; Satpathi, Sagar; Hazra, Partha

    2016-03-29

    In the present work, we have investigated the excited-state proton transfer (ESPT) dynamics inside lipid-based reverse hexagonal (HII), gyroid Ia3d, and diamond Pn3m LLC phases. Polarized light microscopy (PLM) and small-angle X-ray scattering (SAXS) techniques have been employed for the characterization of LLC systems. Time-resolved fluorescence results reveal the retarded ESPT dynamics inside liquid crystalline systems compared to bulk water, and it follows the order HII < Ia3d < Pn3m < H2O. The slower solvation, hampered "Grotthuss" proton transfer process, and most importantly, topological influence, of the LLC systems are believed to be mainly responsible for the slower and different extent of ESPT dynamics. Interestingly, recombination dynamics is found to be faster with respect to bulk water and it follows the order H2O < Pn3m < Ia3d < HII. Faster recombination dynamics arises due to lower dielectric constant and different channel diameters of these LLC systems. However, the dissociation dynamics is found to be slower than bulk water and it follows the order HII < Ia3d < Pn3m < H2O. Differences in critical packing parameter of LLC systems are believed to be the governing factors for the slower dissociation dynamics in these liquid crystalline systems. PMID:26953966

  12. 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.

  13. Liquid sloshing in partly-filled laterally-excited circular tanks equipped with baffles

    NASA Astrophysics Data System (ADS)

    Hasheminejad, Seyyed M.; Mohammadi, M. M.; Jarrahi, Miad

    2014-01-01

    Linear potential theory in conjunction with the conformal mapping technique are employed to develop rigorous mathematical models for two-dimensional transient sloshing in non-deformable baffled horizontal circular cylindrical vessels, filled with inviscid incompressible fluids to arbitrary depths, and subjected to arbitrary time-dependent lateral accelerations. Three common baffle configurations are considered, namely, a pair of free surface-touching horizontal side baffles, and a central surface-piercing or bottom-mounted vertical baffle of arbitrary extension. The first few normalized antisymmetric/symmetric sloshing frequencies of the partially-filled tanks are tabulated for selected baffle extension and fill depth ratios. Also, the effects of liquid fill depth or baffle length parameter on the impulsive, total and modal convective mass ratios are examined. A ramp-step function is used to replicate the lateral acceleration excitation encountered in an idealized turning maneuver. Durbin's numerical Laplace transform inversion scheme was applied to solve the resulting truncated linear sets of ordinary differential equations in the time-domain. The effects of excitation input time, fill level, and baffle configuration/extension on the force and moment amplification factors are illustrated through appropriate design charts. Furthermore, the transient hydrodynamic responses to a real seismic event are calculated and the effectiveness of baffle configuration/length on suppression of the induced destabilizing lateral forces are examined. Limiting cases are considered and rigorous verifications are made by comparison with the available data as well as with the numerical simulations performed by using a commercial CFD software package.

  14. Non-Abelian statistics of Luttinger holes in quantum wells

    NASA Astrophysics Data System (ADS)

    Simion, George; Lyanda-Geller, Yuli

    2015-03-01

    Non-Abelian quasiparticle excitations represent a key element of topologically protected quantum computing. Such exotic states appear in fractional quantum Hall (FQH) effect as eigenstates of N-body interaction potential. These potentials can be obtained by renormalization of electron-electron interactions in the presence of Landau level (LL) mixing. The properties of valence band holes makes them fundamentally different from electrons. In the presence of magnetic field, low-lying states do not exhibit fan-like diagram and several of the levels cross. Variation of magnetic field in the vicinity of level crossings serves as a knob that tunes LL mixing and enhances the 3-body interaction. 1 / 2 filling factor FQH is a state that was not observed in electron liquid, but has been observed for holes. The properties of the two dimensional charged quantum hole liquid in the presence of magnetic field are studied using the spherical geometry. The properties of the novel 1 / 2 state are discussed. Research was supported by the U.S. Department of Energy, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering under Award DE-SC0010544.

  15. 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.

  16. Inelastic electron and Raman scattering from the collective excitations in quantum wires: Zero magnetic field

    NASA Astrophysics Data System (ADS)

    Kushwaha, Manvir S.

    2013-04-01

    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) [or quantum wire(s) for more practical purposes] 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. In the language of condensed matter physics, a critical scrutiny of Q-1DEG systems has provided us with a host of exotic (electronic, optical, and transport) phenomena unseen in their higher- or lower-dimensional counterparts. This has motivated us to undertake a systematic investigation of the inelastic electron scattering (IES) and the inelastic light scattering (ILS) from the elementary electronic excitations in quantum wires. We begin with the Kubo's correlation functions to derive the generalized dielectric function, the inverse dielectric function, and the Dyson equation for the dynamic screened potential in the framework of Bohm-Pines' random-phase approximation. These fundamental tools then lead us to develop methodically the theory of IES and ILS for the Q-1DEG systems. As an application of the general formal results, which know no bounds regarding the subband occupancy, we compute the density of states, the Fermi energy, the full excitation spectrum [comprised of intrasubband and intersubband single-particle as well as collective excitations], the loss functions for the IES and the Raman intensity for the ILS. We observe that it is the collective (plasmon) excitations that largely contribute to the predominant peaks in the energy-loss and the Raman spectra. The inductive reasoning is that the IES can be a potential alternative of the overused ILS for investigating collective excitations in quantum wires. We trust that this research work shall be useful to all - from novice to expert and from theorist to experimentalist - who believe in the power of traditional science.

  17. Evidence of scattering of bulk elementary excitations in isotopically pure liquid helium-II at low temperatures

    NASA Astrophysics Data System (ADS)

    Zakharenko, A. A.

    2010-07-01

    This short report is concerned with experimental investigations of bulk elementary excitations (BEEs) in the isotopically pure liquid helium-II at low temperatures below 100 mK. The evidence of BEEs? scattering is introduced in this work. Two identical Au-heaters were used to generate BEEs. The first pulsed heater generates BEE beams to record them. The second heater serves to generate BEE beams in order to scatter the first beams, operating delay time between pulses of the heaters. Experimental signals were recorded by several bolometers situated both above and below the liquid surface: scattered BEEs are travelling in the liquid from the pulsed heater to the bolometer; scattered BEEs, reaching the liquid surface, evaporate 4He-atoms detected by two bolometers positioned in a vacuum; scattered signals are reflected from the liquid surface back to the liquid and are detected by the other bolometer situated in the liquid. It is manifested that the experimental results showed a dramatic decrease in peaks of recorded signals. Also, signal losses for different heater powers were calculated.

  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. A study on semi-active Tuned Liquid Column Dampers (sTLCDs) for structural response reduction under random excitations

    NASA Astrophysics Data System (ADS)

    Sonmez, E.; Nagarajaiah, S.; Sun, C.; Basu, B.

    2016-02-01

    This paper proposes a new model for semi-active Tuned Liquid Column Damper (sTLCD) where the sTLCD is connected to the primary structure using an adaptive spring. Short time Fourier transformation (STFT) based control algorithms (feedforward and feedback) are developed to control the stiffness of the spring such that the sTLCD is tuned in real-time when the dominant excitation frequency varies or damage occurs to the primary structure. The effectiveness of the proposed sTLCD and the associated control algorithms is examined numerically under random excitations including stationary and non-stationary excitations. Root Mean Square (RMS) response is computed in three cases: with no TLCD, with a passive Tuned Liquid Column Damper (pTLCD) and with the sTLCD. Results indicate that the developed control algorithms are effective in tuning the frequency of the sTLCD in real-time. As a result, the sTLCD provides more robust reduction than the pTLCD because the pTLCD becomes off-tuned and loses its effectiveness when the properties of the excitations or the primary structure vary.

  20. Delayed light emission of Tetraphenyl-butadiene excited by liquid argon scintillation light. Current status and future plans

    NASA Astrophysics Data System (ADS)

    Segreto, E.; Machado, A. A.; Araujo, W.; Teixeira, V.

    2016-02-01

    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, re-emits 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 clarifying the anomalies in liquid-argon scintillation light reported in the literature since the 1970s. Precision measurements of the properties of TPB, when excited by Vacuum Ultra Violet photons are being carried on at the Brazilian Synchrotron Light Laboratory in Campinas (State of São Paulo).

  1. 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.

  2. Cryogenic exciter

    DOEpatents

    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.

  3. 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.

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

    SciTech Connect

    Elsaesser, Thomas Reimann, Klaus; Woerner, Michael

    2015-06-07

    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.

  5. Three-dimensional spacecraft angular momentum fluctuations due to gravity jitter excited slosh waves in liquid propellant system

    NASA Technical Reports Server (NTRS)

    Hung, R. J.; Pan, H. L.; Leslie, F. W.

    1992-01-01

    The paper investigates the dynamical behavior of fluids affected by asymmetric gravity jitter oscillations, in particular the effect of surface tension on partially filled rotating fluids (cryogenic liquid helium and helium vapor) in a subscale Gravity Probe-B spacecraft propellant dewar tank imposed by time-dependent variation in the direction of the background gravity environment. It is shown that lower frequency gravity jitter imposed on the time-dependent variation in the direction of background gravity induced a greater amplitude of oscillations and a stronger degree of asymmetry in liquid-vapor interface geometry than that made by the higher frequency gravity jitter. Fluctuations of angular momentum and spacecraft moment caused by slosh wave excitation are also studied. Slosh-wave-induced fluctuations in angular momentum and moment are important factors in spacecraft dynamics, guidance, and attitude controls.

  6. Minimal-excitation states for electron quantum optics using levitons

    NASA Astrophysics Data System (ADS)

    Dubois, J.; Jullien, T.; Portier, F.; Roche, P.; Cavanna, A.; Jin, Y.; Wegscheider, W.; Roulleau, P.; Glattli, D. C.

    2013-10-01

    The on-demand generation of pure quantum excitations is important for the operation of quantum systems, but it is particularly difficult for a system of fermions. This is because any perturbation affects all states below the Fermi energy, resulting in a complex superposition of particle and hole excitations. However, it was predicted nearly 20 years ago that a Lorentzian time-dependent potential with quantized flux generates a minimal excitation with only one particle and no hole. Here we report that such quasiparticles (hereafter termed levitons) can be generated on demand in a conductor by applying voltage pulses to a contact. Partitioning the excitations with an electronic beam splitter generates a current noise that we use to measure their number. Minimal-excitation states are observed for Lorentzian pulses, whereas for other pulse shapes there are significant contributions from holes. Further identification of levitons is provided in the energy domain with shot-noise spectroscopy, and in the time domain with electronic Hong-Ou-Mandel noise correlations. The latter, obtained by colliding synchronized levitons on a beam splitter, exemplifies the potential use of levitons for quantum information: using linear electron quantum optics in ballistic conductors, it is possible to imagine flying-qubit operation in which the Fermi statistics are exploited to entangle synchronized electrons emitted by distinct sources. Compared with electron sources based on quantum dots, the generation of levitons does not require delicate nanolithography, considerably simplifying the circuitry for scalability. Levitons are not limited to carrying a single charge, and so in a broader context n-particle levitons could find application in the study of full electron counting statistics. But they can also carry a fraction of charge if they are implemented in Luttinger liquids or in fractional quantum Hall edge channels; this allows the study of Abelian and non-Abelian quasiparticles in the time domain. Finally, the generation technique could be applied to cold atomic gases, leading to the possibility of atomic levitons.

  7. 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

  8. 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

    2015-10-01

    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.

  9. 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

  10. Effect of asymmetric gravity jitter excited slosh waves at liquid-vapor interface under microgravity

    NASA Technical Reports Server (NTRS)

    Hung, R. J.; Pan, H. L.; Lee, C. C.; Leslie, F. W.

    1992-01-01

    The dynamical behavior of fluids affected by the asymmetric gravity jitter oscillations, in particular the effect of surface tension on partially-filled rotating fluids (cryogenic liquid helium and helium vapor) in a sub-scale Gravity Probe-B Spacecraft propellant dewar tank imposed by time-dependent various directions of background gravity environment have been investigated. Results show that lower frequency gravity jitter imposed on the time-dependent variations of the direction of background gravity induced a greater amplitude of oscillations and a stronger degree of asymmetry in liquid-vapor interface geometry than that made by the higher frequency gravity jitter. Furthermore, the greater the components of background gravity in radial and circumferential directions will provide a greater contribution in driving more to the increasing amplitude and degrees of symmetry of liquid-vapor interface profiles which, in turn, modify the disturbance of moment of inertia and angular momentum of spacecraft.

  11. Phase diagram of the Kohn-Luttinger superconducting state for bilayer graphene

    NASA Astrophysics Data System (ADS)

    Kagan, Maxim Yu.; Mitskan, Vitaly A.; Korovushkin, Maxim M.

    2015-06-01

    The effect of Coulomb interaction between Dirac fermions on the formation of the Kohn-Luttinger superconducting state in bilayer doped graphene is studied disregarding of the effect of the van der Waals potential of the substrate and impurities. The phase diagram determining the boundaries of superconductive domains with different types of symmetry of the order parameter is built using the extended Hubbard model in the Born weak-coupling approximation with allowance for the intratomic, interatomic, and interlayer Coulomb interactions between electrons. It is shown that the Kohn-Luttinger polarization contributions up to the second order of perturbation theory in the Coulomb interaction inclusively and an account for the long-range intraplane Coulomb interactions significantly affect the competition between the superconducting phases with the f-, p + ip-, and d + id-wave symmetries of the order parameter. It is demonstrated that the account for the interlayer Coulomb interaction enhances the critical temperature of the transition to the superconducting phase.

  12. Photoconductivity induced by single-proton excitation of aromatic molecules in liquid hydrocarbons

    SciTech Connect

    Holroyd, R.A.; Preses, J.M.; Boettcher, E.H.; Schmidt, W.F.

    1984-02-16

    The spectral dependence of the photoconductivity of several aromatic solutes (anthracene, 1,2-benzanthracene, perylene, pyrene, azulene, ..cap alpha..-methylnaphthalene, and triphenylamine) in liquid hydrocarbon solvents (neopentane, 2,2,4-trimethylpentane(2,2,4-TMP), 2,2,4,4-tetramethylpentane (2,2,4,4-TMP), and n-pentane) are reported. In liquids which exhibit high thermal electron mobilities, relative maxima or shoulders are detected in the photoconductivity spectra. The corresponding transitions are thought to involve the formation of Rydberg states as precursors of separated charges. For anthracene and azulene, the transitions occur at approximately the same energy where Rydberg lines are observed in the gas phase. Quenching of the photoconductivity by perfluoromethylcyclohexane and by perfluoro-n-hexane supports this hypothesis.

  13. 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.

  14. Kohn-Luttinger superconductivity in monolayer and bilayer semimetals with the Dirac spectrum

    SciTech Connect

    Kagan, M. Yu.; Mitskan, V. A.; Korovushkin, M. M.

    2014-12-15

    The effect of Coulomb interaction in an ensemble of Dirac fermions on the formation of superconducting pairing in monolayer and bilayer doped graphene is studied using the Kohn-Luttinger mechanism disregarding the Van der Waals potential of the substrate and impurities. The electronic structure of graphene is described using the Shubin-Vonsovsky model taking into account the intratomic, interatomic, and interlayer (in the case of bilayer graphene) Coulomb interactions between electrons. The Cooper instability is determined by solving the Bethe-Saltpeter integral equation. The renormalized scattering amplitude is obtained with allowance for the Kohn-Luttinger polarization contributions up to the second order of perturbation theory in the Coulomb interaction. It plays the role of effective interaction in the Bethe-Salpeter integral equation. It is shown that the allowance for the Kohn-Luttinger renormalizations as well as intersite Coulomb interaction noticeably affects the competition between the superconducting phases with the f-wave and d + id-wave symmetries of the order parameter. It is demonstrated that the superconducting transition temperature for an idealized graphene bilayer with significant interlayer Coulomb interaction between electrons is noticeably higher than in the monolayer case.

  15. Permanent Excitation of Standing Gravity Surface Waves by the Resonant Coalescence of Non-Coalescent Cold and Hot Pure Liquid

    NASA Astrophysics Data System (ADS)

    Schwabe, Dietrich; Hintz, Peter

    2001-02-01

    We describe the continuous excitation of standing gravity surface waves in the free surface of a volatile silicone oil contained in a cylindrical heated vessel (crucible). Resonant coalescence occurred under certain conditions between the fluid in the vessel and a volume of condensed oil which forms at the lower end of a cold copper cylinder in contact from above with the center of the oil surface. The expected continuous coalescence between the cold and the hot fluid volumes does not occur if the cold cylinder is raised above a critical height from the fluid surface forming a free-standing liquid column (meniscus). The standing waves frequency is fixed by the geometry and repeated partial coalescence events are triggered by the standing wave. The thermal Marangoni effect during the partial coalescence events leads to resonant wave amplification.

  16. 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)

  17. Magnetic excitations in Kondo liquid: superconductivity and hidden magnetic quantum critical fluctuations

    SciTech Connect

    Yang, Yifeng; Urbano, Ricardo; Nicholas, Curro; Pines, David

    2009-01-01

    We report Knight shift experiments on the superconducting heavy electron material CeCoIn{sub 5} that allow one to track with some precision the behavior of the heavy electron Kondo liquid in the superconducting state with results in agreement with BCS theory. An analysis of the {sup 115}In nuclear quadrupole resonance (NQR) spin-lattice relaxation rate T{sub 1}{sup -1} measurements under pressure reveals the presence of 2d magnetic quantum critical fluctuations in the heavy electron component that are a promising candidate for the pairing mechanism in this material. Our results are consistent with an antiferromagnetic quantum critical point (QCP) located at slightly negative pressure in CeCoIn{sub 5} and provide additional evidence for significant similarities between the heavy electron materials and the high T{sub c} cuprates.

  18. Magnetic excitations in the kondo liquid: superconductivity and hidden magnetic quantum critical fluctuations.

    PubMed

    Yang, Yi-Feng; Urbano, Ricardo; Curro, Nicholas J; Pines, David; Bauer, E D

    2009-11-01

    We report Knight-shift experiments on the superconducting heavy-electron material CeCoIn5 that allow one to track with some precision the behavior of the heavy-electron Kondo liquid in the superconducting state with results in agreement with BCS theory. An analysis of the 115In nuclear quadrupole resonance spin-lattice relaxation rate T1(-1) measurements under pressure reveals the presence of 2d magnetic quantum critical fluctuations in the heavy-electron component that are a promising candidate for the pairing mechanism in this material. Our results are consistent with an antiferromagnetic quantum critical point located at slightly negative pressure in CeCoIn5 and provide additional evidence for significant similarities between the heavy-electron materials and the high-T(c) cuprates. PMID:20365948

  19. Elementary Excitations in Solid and Liquid 4He at the Melting Pressure

    NASA Astrophysics Data System (ADS)

    Todoshchenko, I. A.; Alles, H.; Junes, H. J.; Manninen, M. S.; Parshin, A. Y.; Tsepelin, V.

    2008-02-01

    Recent discovery of a nonclassical rotational inertia (NCRI) in solid 4He below 0.2 K by Kim and Chan has revived great interest in the problem of supersolidity and initiated intensive study on the properties of solid 4He. A direct proof that the onset of NCRI corresponds to the supersolid transition would be the observation of a corresponding drop of the entropy of solid 4He below the transition temperature. We have measured the melting pressure of ultrapure 4He in the temperature range from 0.01 to 0.45 K with several single crystals grown at different pressures and with the accuracy of 0.5 μbar. In addition, supplementary measurements of the pressure in liquid 4He at constant volume have been performed, which allowed us to eliminate the contribution of the temperature-dependent properties of the pressure gauge from the measured melting pressure data. With the correction to the temperature-dependent sensitivity of the pressure gauge, the variation of the melting pressure of 4He below 320 mK obeys the pure T 4 law due to phonons with the accuracy of 0.5 μbar, and no sign of the transition is seen (Todoshchenko et al. in JETP Lett. 85:454, 2007). This sets the upper limit of ˜5ṡ10-8 R for a possible excess entropy in high-quality 4He crystals below 320 mK. At higher temperatures the contribution from rotons in the superfluid 4He has been observed. The thermal expansion coefficient of the superfluid 4He has been measured in the range from 0.01 to 0.7 K with the accuracy of ˜10-7 1/K, or by two orders of magnitude better than in previous measurements. The roton contributions to the melting pressure and to the pressure in liquid at a constant volume are consistent and yield the value of 6.8 K for the roton gap, which is very close to the values obtained with other methods. As no contribution due to weakly interacting vacancies to the melting pressure of 4He has been observed, the lower limit of about 5.5 K for their activation energy can be set.

  20. 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.

  1. 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.

  2. Transient, polarity-dependent dielectric response in a twisted nematic liquid crystal under very low frequency excitation.

    PubMed

    Krishnamurthy, K S

    2015-09-01

    The electric Freedericksz transition is a second-order quadratic effect, which, in a planarly aligned nematic liquid crystal layer, manifests above a threshold field as a homogeneous symmetric distortion with maximum director-tilt in the midplane. We find that, upon excitation by a low frequency (<0.2Hz) square-wave field, the instability becomes spatially and temporally varying. This is demonstrated using calamitic liquid crystals, initially in the 90°-twisted planar configuration. The distortion occurs close to the negative electrode following each polarity switch and, for low-voltage amplitudes, decays completely in time. We use the elastically favorable geometry of Brochard-Leger walls to establish the location of maximum distortion. Thus, at successive polarity changes, the direction of extension of both annular and open walls switches between the alignment directions at the two substrates. For high voltages, this direction is largely along the midplane director, while remaining marginally oscillatory. These results are broadly understood by taking into account the time-varying and inhomogeneous field conditions that prevail soon after the polarity reverses. Polarity dependence of the instability is traced to the formation of intrinsic double layers that lead to an asymmetry in field distribution in the presence of an external bias. Momentary field elevation near the negative electrode following a voltage sign reversal leads to locally enhanced dielectric and gradient flexoelectric torques, which accounts for the surface-like phenomenon observed at low voltages. These spatiotemporal effects, also found earlier for other instabilities, are generic in nature. PMID:26465487

  3. Phonon-Induced Resistivity of Electron Liquids in Quantum Wires

    NASA Astrophysics Data System (ADS)

    Seelig, Georg; Matveev, K. A.; Andreev, A. V.

    2005-02-01

    We study the resistivity of a quantum wire caused by backscattering of electrons by acoustic phonons. In the presence of Coulomb interactions, backscattering is strongly enhanced at low temperatures due to Luttinger liquid effects. Information about the strength of the interactions can be obtained from a measurement of the temperature dependence of the resistivity.

  4. Phonon-induced resistivity of electron liquids in quantum wires.

    PubMed

    Seelig, Georg; Matveev, K A; Andreev, A V

    2005-02-18

    We study the resistivity of a quantum wire caused by backscattering of electrons by acoustic phonons. In the presence of Coulomb interactions, backscattering is strongly enhanced at low temperatures due to Luttinger liquid effects. Information about the strength of the interactions can be obtained from a measurement of the temperature dependence of the resistivity. PMID:15783764

  5. Excitation spectra and correlation functions of quantum Su-Schrieffer-Heeger models

    NASA Astrophysics Data System (ADS)

    Weber, Manuel; Assaad, Fakher F.; Hohenadler, Martin

    2015-06-01

    We study one-dimensional Su-Schrieffer-Heeger (SSH) models with quantum phonons using a continuous-time quantum Monte Carlo method. Within statistical errors, we obtain identical results for the SSH model with acoustic phonons, and a related model with a coupling to an optical bond phonon mode. Based on this agreement, we first study the Peierls metal-insulator transition of the spinless SSH model, and relate it to the Kosterlitz-Thouless transition of a spinless Luttinger liquid. In the Peierls phase, the spectral functions reveal the single-particle and charge gap, and a central peak related to long-range order. For the spinful SSH model, which has a dimerized ground state for any nonzero coupling, we reveal a symmetry-related degeneracy of spin and charge excitations, and the expected spin and charge gaps as well as a central peak. Finally, we study the SSH-U V model with electron-phonon and electron-electron interaction. We observe a Mott phase with critical spin and bond correlations at weak electron-phonon coupling, and a Peierls phase with gapped spin excitations at strong coupling. We relate our findings to the extended Hubbard model, and discuss the physical origin of the agreement between optical and acoustic phonons.

  6. Nucleon effective E-mass in neutron-rich matter from the Migdal-Luttinger jump

    NASA Astrophysics Data System (ADS)

    Cai, Bao-Jun; Li, Bao-An

    2016-06-01

    The well-known Migdal-Luttinger theorem states that the jump of the single-nucleon momentum distribution at the Fermi surface is equal to the inverse of the nucleon effective E-mass. Recent experiments studying short-range correlations (SRC) in nuclei using electron-nucleus scatterings at the Jefferson National Laboratory (JLAB) together with model calculations constrained significantly the Migdal-Luttinger jump at saturation density of nuclear matter. We show that the corresponding nucleon effective E-mass is consequently constrained to M0*,E / M ≈ 2.22 ± 0.35 in symmetric nuclear matter (SNM) and the E-mass of neutrons is smaller than that of protons in neutron-rich matter. Moreover, the average depletion of the nucleon Fermi sea increases (decreases) approximately linearly with the isospin asymmetry δ according to κp/n ≈ 0.21 ± 0.06 ± (0.19 ± 0.08) δ for protons (neutrons). These results will help improve our knowledge about the space-time non-locality of the single-nucleon potential in neutron-rich nucleonic matter useful in both nuclear physics and astrophysics.

  7. Response of Helical Luttinger Liquid in InAs/GaSb Edges to a Magnetic Field

    NASA Astrophysics Data System (ADS)

    Li, Tingxin; Tong, Bingbing; Liu, Xiaoxue; Han, Zhongdong; Zhang, Chi; Sullivan, Gerard; Du, Rui-Rui

    Electron-electron interactions have been shown to play an important role in InAs/GaSb quantum spin Hall (QSH) edge states, leading to power-law behaviors of the helical edge conductance as a function of temperature and bias voltage (Li et al., Phys. Rev. Lett. 115 136804). A variety of inelastic and/or multiparticle backscattering processes could occur in helical edges when taking electron-electron interactions into account. On the other hand, in the presence of an external magnetic field, single-particle elastic backscattering is also allowed in QSH edge due to the breaking of time-reversal symmetry (TRS). It would be interesting to pursue experimental investigations for the combined effect of electron-electron interactions and TRS breaking on QSH edge transport. We report work in progress for low temperature conductance measurements of the helical edge in InAs/GaSb under perpendicular or in-plane magnetic fields. We found that the magnetic field responses are generally correlated with the interaction strength in the edge states. The work at Peking University were supported by NBRPC Grants (No. 2012CB921301 and No. 2014CB920901), and by Collaborative Innovation Center of Quantum Matter.

  8. Dimensional crossover in a Fermi gas and a cross-dimensional Tomonaga-Luttinger model

    NASA Astrophysics Data System (ADS)

    Lang, Guillaume; Hekking, Frank; Minguzzi, Anna

    2016-01-01

    We describe the dimensional crossover in a noninteracting Fermi gas in an anisotropic trap, obtained by populating various transverse modes of the trap. We study the dynamical structure factor and drag force. Starting from a dimension d , the (d +1 ) -dimensional case is obtained to a good approximation with relatively few modes. We show that the dynamical structure factor of a gas in a d -dimensional harmonic trap simulates an effective 2 d -dimensional box trap. We focus then on the experimentally relevant situation when only a portion of the gas in harmonic confinement is probed and give a condition to obtain the behavior of a d -dimensional gas in a box. Finally, we propose a generalized Tomonaga-Luttinger model for the multimode configuration and compare the dynamical structure factor in the two-dimensional limit with the exact result, finding that it is accurate in the backscattering region and at low energy.

  9. 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.

  10. Search for 2 ν β β decay of 136Xe to the 01+ excited state of 136Ba with the EXO-200 liquid xenon detector

    NASA Astrophysics Data System (ADS)

    Albert, J. B.; Auty, D. J.; Barbeau, P. S.; Beck, D.; Belov, V.; Breidenbach, M.; Brunner, T.; Burenkov, A.; Cao, G. F.; Chambers, C.; Chaves, J.; Cleveland, B.; Coon, M.; Craycraft, A.; Daniels, T.; Danilov, M.; Daugherty, S. J.; Davis, J.; Delaquis, S.; Der Mesrobian-Kabakian, A.; DeVoe, R.; Didberidze, T.; Dilling, J.; Dolgolenko, A.; Dolinski, M. J.; Dunford, M.; Fairbank, W.; Farine, J.; Feldmeier, W.; Feyzbakhsh, S.; Fierlinger, P.; Fudenberg, D.; Gornea, R.; Graham, K.; Gratta, G.; Hall, C.; Hughes, M.; Jewell, M. J.; Johnson, A.; Johnson, T. N.; Johnston, S.; Karelin, A.; Kaufman, L. J.; Killick, R.; King, J.; Koffas, T.; Kravitz, S.; Krücken, R.; Kuchenkov, A.; Kumar, K. S.; Leonard, D. S.; Licciardi, C.; Lin, Y. H.; Ling, J.; MacLellan, R.; Marino, M. G.; Mong, B.; Moore, D.; Njoya, O.; Nelson, R.; Odian, A.; Ostrovskiy, I.; Piepke, A.; Pocar, A.; Prescott, C. Y.; Retière, F.; Rowson, P. C.; Russell, J. J.; Schubert, A.; Sinclair, D.; Smith, E.; Stekhanov, V.; Tarka, M.; Tolba, T.; Tsang, R.; Twelker, K.; Vogel, P.; Vuilleumier, J.-L.; Waite, A.; Walton, J.; Walton, T.; Weber, M.; Wen, L. J.; Wichoski, U.; Winick, T. A.; Wood, J.; Xu, Q. Y.; Yang, L.; Yen, Y.-R.; Zeldovich, O. Ya.; EXO-200 Collaboration

    2016-03-01

    EXO-200 is a single phase liquid xenon detector designed to search for neutrinoless β β decay of 136Xe to the ground state of 136Ba. We report here on a search for the two-neutrino β β decay of 136Xe to the first 0+ excited state, 01+, of 136Ba based on a 100 kg yr exposure of 136Xe. Using a specialized analysis employing a machine learning algorithm, we obtain a 90% CL half-life sensitivity of 1.7 ×1024 yr. We find no statistically significant evidence for the 2 ν β β decay to the excited state resulting in a lower limit of T1/2 2 ν (0+→01+) > 6.9 ×1023 yr at 90% CL. This observed limit is consistent with the estimated half-life of 2.5 ×1025 yr.

  11. 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; Lbcke, 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

  12. The influence of temperature on red-edge excitation effects in liquid solutions of N, N'-dimethylaminobenzonitrile

    NASA Astrophysics Data System (ADS)

    Tomin, V. I.; Wlodarkiewicz, A.

    2013-07-01

    A systematic study of new photophysical and photochemical processes in solutions is continued by the example of a recently found phenomenon of redistribution of the intensities of two fluorescence bands of N, N'-Dimethylaminobenzonitrile (DMABN) in polar solutions at room temperatures under selective irradiation by light with different photon energies in the region of the long-wavelength absorption band. The effects observed are explained using data of quantum-mechanical calculations, which reveal that solutions of these systems are very likely to contain rotational isomers with different orientations of the dimethylamino group with respect to the plane of the benzonitrile residue. The excited-state charge transfer reactions in these rotamers occur in different ways and, hence, with different rates, because of which the intensity ratio of recorded fluorescence bands is different for different wavelengths of selective excitation. In this study, the influence of the temperature on the red-edge excitation effect observed in the fluorescence of DMABN solutions in acetonitrile is studied in the temperature range of 274-313 K using the previously used selective excitation method. It is found that these effects manifest themselves at any temperature within this range, but are especially strong at 313 K. The parameters of the dual fluorescence that are most sensitive for recording of the considered effects are determined, and the obtained temperature dependences are interpreted.

  13. Study on the Influence of Liquid in an Annular Region on Sliding Motion of a Dual Structure Subjected to Base Excitation

    NASA Astrophysics Data System (ADS)

    Furuta, Kazuhisa; Ito, Tomohiro; Shintani, Atsuhiko

    In nuclear power stations, the storage of a lot of spent fuels is becoming a serious problem because of the shortage of the residual space of the spent fuel pool. It is planned to construct an another plant where the spent fuels are temporarily stored. In that plant, the spent fuels will be installed in a container called canister. The canister, in turn, will be stored in an outer cylindrical container called cask, which will be a free-standing structure. Thus, the cask-canister system is seen as a two-degree-of-freedom coupled system. Therefore, it is very important to evaluate the sliding motion of the cask-canister system subjected to seismic excitations. In an analytical model, the canister and the cask are treated as rigid bodies that are connected by a spring and a dashpot, and liquid is encapsulated in an annular region between the cask and the canister. The equations of motion are derived for the sliding motion when the floor is subjected to a horizontal base excitation. The sliding displacement of the cask and the relative displacement of the canister against the cask are evaluated by numerical simulations. The effects of the liquid in the annular region is effective in reducing the sliding motion of the cask.

  14. 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.

  15. An apparatus for pulsed ESR and DNP experiments using optically excited triplet states down to liquid helium temperatures

    NASA Astrophysics Data System (ADS)

    Eichhorn, T. R.; Haag, M.; van den Brandt, B.; Hautle, P.; Wenckebach, W. Th.; Jannin, S.; van der Klink, J. J.; Comment, A.

    2013-09-01

    In standard Dynamic Nuclear Polarization (DNP) electron spins are polarized at low temperatures in a strong magnetic field and this polarization is transferred to the nuclear spins by means of a microwave field. To obtain high nuclear polarizations cryogenic equipment reaching temperatures of 1 K or below and superconducting magnets delivering several Tesla are required. This equipment strongly limits applications in nuclear and particle physics where beams of particles interact with the polarized nuclei, as well as in neutron scattering science. The problem can be solved using short-lived optically excited triplet states delivering the electron spin. The spin is polarized in the optical excitation process and both the cryogenic equipment and magnet can be simplified significantly. A versatile apparatus is described that allows to perform pulsed dynamic nuclear polarization experiments at X-band using short-lived optically excited triplet sates. The efficient 4He flow cryostat that cools the sample to temperatures between 4 K and 300 K has an optical access with a coupling stage for a fiber transporting the light from a dedicated laser system. It is further designed to be operated on a neutron beam. A combined pulse ESR/DNP spectrometer has been developed to observe and characterize the triplet states and to perform pulse DNP experiments. The ESR probe is based on a dielectric ring resonator of 7 mm inner diameter that can accommodate cubic samples of 5 mm length needed for neutron experiments. NMR measurements can be performed during DNP with a coil integrated in the cavity. With the presented apparatus a proton polarization of 0.5 has been achieved at 0.3 T.

  16. Collective excitations of strongly coupled bilayer charged Bose liquids in the third-frequency-moment sum rule

    SciTech Connect

    Tas, Murat; Tanatar, B.

    2008-09-15

    We calculate the collective excitation modes of strongly coupled bilayer charged Bose systems. We employ the dielectric matrix formulation to study the correlation effects within the random-phase approximation (RPA), the self consistent field approximation Singwi, Tosi, Land, and Sjoelander (STLS), and the quasilocalized charge approximation (QLCA), which satisfies the third-frequency-moment (<{omega}{sup 3}>) sum rule. We find that the QLCA predicts a long-wavelength correlation-induced energy gap in the out-of-phase plasmon mode, similar to the situation in electronic bilayer systems. The energy gap and the plasmon density of states are studied as a function of interlayer separation and coupling parameter r{sub s}. The results should be helpful for experimental investigations.

  17. Multifrequency force microscopy using flexural and torsional modes by photothermal excitation in liquid: atomic resolution imaging of calcite (10\\bar{1}4)

    NASA Astrophysics Data System (ADS)

    Meier, Tobias; Eslami, Babak; Solares, Santiago D.

    2016-02-01

    We introduce a new multifrequency atomic force microscopy (AFM) method which involves the excitation of flexural and torsional eigenmodes of the microcantilever probe in liquid environments. The flexural and torsional deflection signals are mostly decoupled in the majority of commercial AFM setups, so they can be relatively easily recorded and processed. The use of torsional modes provides additional surface information at the atomic scale, with respect to flexural mode imaging alone, although the flexural modes are the only ones capable of ‘true’ atomic resolution imaging. In our experiments, the torsional modes are shown to be particularly sensitive to protruding oxygen surface atoms on the calcite (10\\bar{1}4) plane. The high lateral resolution capability of the flexural modes, combined with the high sensitivity of the torsional modes to specific surface features in liquid environments, can thus offer the means of observing chemical contrast at the atomic level using purely mechanical measurement AFM techniques, even in the absence of tip functionalization.

  18. Magnetically stabilized nematic order. II. Critical states and algebraically ordered nematic spin liquids in one-dimensional optical lattices

    SciTech Connect

    Zhai Hui; Zhou Fei

    2005-07-01

    We investigate the Zeeman-field-driven quantum phase transitions between singlet spin liquids and algebraically ordered O(2) nematic spin liquids of spin-one bosons in one-dimensional optical lattices. We find that the critical behavior is characterized by condensation of hardcore bosons instead of ideal magnons in high-dimensional lattices. Critical exponents are strongly renormalized by hardcore interactions and critical states are equivalent to the free Fermion model up to the Friedel oscillations. We also find that the algebraically ordered nematic spin liquids close to critical points are fully characterized by the Luttinger-liquid dynamics with Luttinger-liquid parameters magnetically tunable. The Bethe ansatz solution has been applied to determine the critical magnetization and nematic correlations.

  19. Excited State Dynamics of Ru10 Cluster Interfacing Anatase TiO2(101) Surface and Liquid Water.

    PubMed

    Huang, Shuping; Inerbaev, Talgat M; Kilin, Dmitri S

    2014-08-21

    Charge transfer dynamics at the interface of supported metal nanocluster and liquid water by GGA+U calculations combined with density matrix formalism is considered. The Ru10 cluster introduces new states into the band gap of TiO2 surface, narrows the band gap of TiO2, and enhances the absorption strength. The H2O adsorption significantly enhances the intensity of photon absorption, which is due to the formation of Ti-O(water) and Ru-O(water) bonds at the interfaces. The Ru10 cluster promotes the dissociation of water, facilitates charge transfer, and increases the relaxation rates of holes and electrons. We expect that our results are helpful in understanding basic processes contributing to photoelectrochemical water splitting. PMID:26278085

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. Effect of the Long-Range Coulomb Interaction on the Phase Diagram of the Kohn-Luttinger Superconducting State in Idealized Graphene

    NASA Astrophysics Data System (ADS)

    Kagan, M. Yu.; Mitskan, V. A.; Korovushkin, M. M.

    2015-12-01

    The effect of the long-range Coulomb interaction on the formation of the Kohn-Luttinger superconductivity in monolayer doped graphene is studied disregarding the Van der Waals potential of the substrate and both magnetic and non-magnetic impurities. It is shown that the allowance for the Kohn-Luttinger renormalizations up to the second order in perturbation theory in the on-site Hubbard interaction inclusively, as well as in the intersite Coulomb interaction, significantly affects the interplay between the superconducting phases with the f-wave, p+ip -wave, and d + id -wave symmetries of the order parameter. It is demonstrated that taking Coulomb repulsion of electrons located at the next-nearest neighboring atoms in such a system into account changes qualitatively the phase diagram and enhances the critical temperature of the transition to the superconducting phase.

  6. Mise en évidence d'états excités dans les spectres de photoionisation du cyclohexane et du diméthyl 2-2-butane liquides

    NASA Astrophysics Data System (ADS)

    Casanovas, J.; Guelfucci, J. P.; Caselles, O.

    1991-07-01

    Excited states are probably occurring, at an intermediate stage, in the VUV photoionization process of liquid hydrocarbons, as suggested by a Stern-Volmer behaviour when interacting with electron quenchers. They are here detected in the VUV photoionization spectrum of cyclohexane and dimethyl-2-2-butane in liquid phase. Some of the discernable peaks can be assigned as valence and Rydberg states, yet observed in gas phase. Supplementary peaks are observed, the existence of which is to be interpretated. L'existence d'états excités dans le processus de photoionisation VUV des hydrocarbures en phase liquide - précédemment suggérée par l'observation de la loi de Stern-Volmer lors de l'interaction avec des capteurs d'électrons - est ici détectée en traçant le spectre de photoionisation VUV du cyclohexane et du diméthyl-2-2-butane purs en phase liquide. Certains des pics observés coïncident avec les états de valence et de Rydberg de ces mêmes corps en phase gaz. Il apparaît des pics supplémentaires dont la nature doit être précisée.

  7. 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

  8. Deuterated analogues as internal reference compounds for the direct determination of benzo(a)pyrene and perylene in liquid fuels by laser-excited Shpol'skii spectrometry

    SciTech Connect

    Yen Yang

    1981-11-01

    The polycyclic aromatic hydrocarbon (PAH) content of coal liquefaction products and other liquid fuels is usually assessed by measuring the benzo(a)pyrene content. In Shpol'skii effect spectrometry, PAHs and their deuterated analogues exhibit adequately resolved characteristic quasi-line spectra. The authors have used deuterated benzo(a)pyrene and perylene as externally added internal reference compounds to facilitate the direct determination of benzo(a)pyrene and perylene in liquid fuels.

  9. Common non-Fermi liquid phases in quantum impurity physics

    NASA Astrophysics Data System (ADS)

    Logan, David E.; Tucker, Adam P.; Galpin, Martin R.

    2014-08-01

    We study correlated quantum impurity models that undergo a local quantum phase transition (QPT) from a strong coupling, Fermi liquid phase to a non-Fermi liquid phase with a globally doubly degenerate ground state. Our aim is to establish what can be shown exactly about such "local moment" (LM) phases, of which the permanent (zero-field) local magnetization is a hallmark, and an order parameter for the QPT. A description of the zero-field LM phase is shown to require two distinct self-energies, which reflect the broken symmetry nature of the phase and together determine the single self-energy of standard field theory. Distinct Friedel sum rules for each phase are obtained, via a Luttinger theorem embodied in the vanishing of appropriate Luttinger integrals. By contrast, the standard Luttinger integral is nonzero in the LM phase but found to have universal magnitude. A range of spin susceptibilites are also considered, including that corresponding to the local order parameter, whose exact form is shown to be RPA-like, and to diverge as the QPT is approached. Particular attention is given to the pseudogap Anderson model, including the basic physical picture of the transition, the low-energy behavior of single-particle dynamics, the quantum critical point itself, and the rather subtle effect of an applied local field. A two-level impurity model that undergoes a QPT ("singlet-triplet") to an underscreened LM phase is also considered, for which we derive on general grounds some key results for the zero-bias conductance in both phases.

  10. Deuterated analogues as internal reference compounds for the direct determination of benzo(a)pyrene and perylene in liquid fuels by laser-excited Shpol'skii spectrometry

    SciTech Connect

    Yang, Y.; D'Silva, A.P.; Fassel, V.A.

    1981-11-01

    In Shpol'skii effect spectrometry, polycyclic aromatic hydrocarbons and their deuterated analogues exhibit adequately resolved characteristic quasi-line spectra. Deuterated benzo(a)pyrene and perylene have been utilized as externally added internal reference compounds to facilitate the direct determination of benzo(a)pyrene and perylene in liquid fuels.

  11. Construction of theory of a binary mixture of nonideal bose gases (or liquids) by the method of collective variables I. Wave function and ground-state energy, excitation spectrum, correlation functions, thermodynamics of the system at t = 0

    SciTech Connect

    Balabanyan, G.O.

    1986-07-01

    For a binary mixture of nonideal Bose gases (or liquids) the method of collective variables is used to find the energy and wave function of the ground-state and the excitation spectrum. The density-density correlation functions are calculated, and the thermodynamics of the system at T = 0 is considered. In the case of a binary mixture of gases with equal masses of the particles it is established in the framework of the model with ''pseudopotential of hard spheres'' that separation of the mixture into components does not occur in two cases: low density of the mixture and any concentration of the admixture or any density and a low concentration of the admixture. The possiblility of a superfluid state is established. The system is also investigated by the variational method. The application of the theory to real binary Bose mixtures, for example, He/sup 4/ and D/sub 2/ or He/sup 4/ and HT is discussed.

  12. Magnetostrictive resonance excitation

    DOEpatents

    Schwarz, Ricardo B.; Kuokkala, Veli-Tapani

    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.

  13. 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

  14. 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)

  15. Highly sensitive quantitation of pesticides in fruit juice samples by modeling four-way data gathered with high-performance liquid chromatography with fluorescence excitation-emission detection.

    PubMed

    Montemurro, Milagros; Pinto, Licarion; Véras, Germano; de Araújo Gomes, Adriano; Culzoni, María J; Ugulino de Araújo, Mário C; Goicoechea, Héctor C

    2016-07-01

    A study regarding the acquisition and analytical utilization of four-way data acquired by monitoring excitation-emission fluorescence matrices at different elution time points in a fast HPLC procedure is presented. The data were modeled with three well-known algorithms: PARAFAC, U-PLS/RTL and MCR-ALS, the latter conveniently adapted to model third-order data. The second-order advantage was exploited when analyzing samples containing uncalibrated components. The best results were furnished with the algorithm U-PLS/RTL. This fact is indicative of both no peak time shifts occurrence among samples and high colinearity among spectra. Besides, this latent-variable structured algorithm is capable of better handle the need of achieving high sensitivity for the analysis of one of the analytes. In addition, a significant enhancement in both predictions and analytical figures of merit was observed for carbendazim, thiabendazole, fuberidazole, carbofuran, carbaryl and 1-naphtol, when going from second- to third-order data. LODs obtained were ranged between 0.02 and 2.4μgL(-1). PMID:27154667

  16. 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.

  17. Self-consistent dual boson approach to single-particle and collective excitations in correlated systems

    NASA Astrophysics Data System (ADS)

    Stepanov, E. A.; van Loon, E. G. C. P.; Katanin, A. A.; Lichtenstein, A. I.; Katsnelson, M. I.; Rubtsov, A. N.

    2016-01-01

    We propose an efficient dual boson scheme, which extends the dynamical mean-field theory paradigm to collective excitations in correlated systems. The theory is fully self-consistent both on the one- and on the two-particle level, thus describing the formation of collective modes as well as the renormalization of electronic and bosonic spectra on equal footing. The method employs an effective impurity model comprising both fermionic and bosonic hybridization functions. Only single- and two-electron Green's functions of the reference problem enter the theory, due to the optimal choice of the self-consistency condition for the effective bosonic bath. We show that the theory is naturally described by a dual Luttinger-Ward functional and obeys the relevant conservation laws.

  18. White-light-exciting, layer-by-layer-assembled ZnCdHgSe quantum dots/polymerized ionic liquid hybrid film for highly sensitive photoelectrochemical immunosensing of neuron specific enolase.

    PubMed

    Yu, Xiangyang; Wang, Yanying; Chen, Xuemin; Wu, Kangbing; Chen, Danchao; Ma, Ming; Huang, Zhenjia; Wu, Wangze; Li, Chunya

    2015-04-21

    ZnCdHgSe quantum dots (QDs) functionalized with N-acetyl-l-cysteine were synthesized and characterized. Through layer-by-layer assembling, the ZnCdHgSe QDs was integrated with a polymerized 1-decyl-3-[3-pyrrole-1-yl-propyl]imidazolium tetrafluoroborate (PDPIT) ionic liquid film modified indium tin oxide (ITO) electrode to fabricated a photoelectrochemical interface for the immobilization of rabbit antihuman neuron specific enolase (anti-NSE). After being treated with glutaraldehyde vapor and bovine serum albumin successively, an anti-NSE/ZnCdHgSe QDs/PDPIT/ITO sensing platform was established. Simplely using a white-light LED as an excitation source, the immunoassay of neuron specific enolase (NSE) was achieved through monitoring the photocurrent variation. The polymerized ionic liquid film was demonstrated to be an important element to enhance the photocurrent response of ZnCdHgSe QDs. The anti-NSE/ZnCdHgSe QDs/PDPIT/ITO based immunosensor presents excellent performances in neuron specific enolase determination. The photocurrent variation before and after being interacted with NSE exhibits a good linear relationship with the logarithm of its concentration (log cNSE) in the range from 1.0 pg mL(-1) to 100 ng mL(-1). The limit of detection of this immunosensor is able to reach 0.2 pg mL(-1) (S/N = 3). The determination of NSE in clinical human sera was also demonstrated using anti-NSE/ZnCdHgSe QDs/PDPIT/ITO electrode. The results were found comparable with those obtained by using enzyme-linked immunosorbent assay method. PMID:25790014

  19. 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 0.24gL(-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

  20. Hydrodynamic pressure in liquid filled container

    NASA Astrophysics Data System (ADS)

    Maiti, Pabitra Ranjan

    2011-12-01

    Liquid storage tanks are used to store oil, drinking water and different liquids which are necessary in industry and energy production. Partially liquid filled container shows free surface movement under external excitation this phenomenon is known as sloshing of liquid. When external excitation frequency matches the natural frequency of sloshing, a violent oscillation may occur that causes excess dynamic pressure on the tank structure. The dynamic behavior of liquid storage tanks under seismic excitation has been the subject of numerous theoretical and experimental investigations. This paper presents a pressure based finite element analysis of the liquid-structure systems considering the coupled effect of elastic structure and liquid. The equation of motion of the liquid is considered as incompressible and inviscid. The hydrodynamic pressure variation along a wall of prismatic container is studied and presented for different fill depth of liquid under sinusoidal base excitation.

  1. Hole subband states of GaAs/AlxGa1-xAs quantum wells within the 6×6 Luttinger model

    NASA Astrophysics Data System (ADS)

    Edwards, G.; Valadares, E. C.; Sheard, F. W.

    1994-09-01

    We present an exact solution for the hole subband dispersion of a [001] symmetric GaAs/AlxGa1-xAs quantum well within the 6×6 Luttinger model, which extends previous work by Andreani, Pasquarello, and Bassani, Phys. Rev. B 36, 5887 (1987) for the 4×4 case. We employ symmetry arguments to decouple the Kramers doubly degenerate subband states and build well-defined parity states of the quantum-well reflection operator, which include the spin-split-off band. Numerical results are presented for the hole subband states and in-plane dispersion curves of a 66-Å AlAs-GaAs-AlAs quantum well, which show anticrossing behavior. The nature of anticrossings between the first and second and the eighth and ninth subbands is investigated by studying the bulk state decomposition of the envelope functions. In the vicinity of the first and second subband anticrossing, there is a negligible bulk GaAs spin-split-off band content. In contrast, in the region of the anticrossing for the higher eighth and ninth subband states, there is considerable GaAs spin-split-off band amplitude, as the GaAs spin-split-off band is nearby in energy.

  2. Synthetic helical liquids with ultracold atoms in optical lattices

    NASA Astrophysics Data System (ADS)

    Budich, J. C.; Laflamme, C.; Tschirsich, F.; Montangero, S.; Zoller, P.

    2015-12-01

    We discuss a platform for the synthetic realization of key physical properties of helical Tomonaga Luttinger liquids (HTLLs) with ultracold fermionic atoms in one-dimensional optical lattices. The HTLL is a strongly correlated metallic state where spin polarization and propagation direction of the itinerant particles are locked to each other. We propose an unconventional one-dimensional Fermi-Hubbard model which, at quarter filling, resembles the HTLL in the long wavelength limit, as we demonstrate with a combination of analytical (bosonization) and numerical (density matrix renormalization group) methods. An experimentally feasible scheme is provided for the realization of this model with ultracold fermionic atoms in optical lattices. Finally, we discuss how the robustness of the HTLL against backscattering and imperfections, well known from its realization at the edge of two-dimensional topological insulators, is reflected in the synthetic one-dimensional scenario proposed here.

  3. 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 across it. Thus the interface can sustain fields of the order of 106 V/cm, which are localized in a nanoscopic layer near the interface. This gives many new options for building various kinds of electrically tunable self assembled moloecular devices. Through the years, ITIES have been considered by electrochemists as a popular biomimetic model system, or for studies of interfacial reaction kinetics; ITIES were also used in industrial phase-transfer catalysis. Recently, this system has opened up new options for nano-scale engineering of functional assemblies (for dense information storage, efficient energy conversion, light-harvesting, and miniaturized sensors), which justifies its presentation in this issue.

  4. RESONANT CAVITY EXCITATION SYSTEM

    DOEpatents

    Baker, W.R.; Kerns, Q.A.; Riedel, J.

    1959-01-13

    An apparatus is presented for exciting a cavity resonator with a minimum of difficulty and, more specifically describes a sub-exciter and an amplifier type pre-exciter for the high-frequency cxcitation of large cavities. Instead of applying full voltage to the main oscillator, a sub-excitation voltage is initially used to establish a base level of oscillation in the cavity. A portion of the cavity encrgy is coupled to the input of the pre-exciter where it is amplified and fed back into the cavity when the pre-exciter is energized. After the voltage in the cavity resonator has reached maximum value under excitation by the pre-exciter, full voltage is applied to the oscillator and the pre-exciter is tunned off. The cavity is then excited to the maximum high voltage value of radio frequency by the oscillator.

  5. 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 σ(xy)∼M0.51. PMID:24289698

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

    NASA Astrophysics Data System (ADS)

    Tooski, S. B.; Ramšak, A.; Bułka, 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.

  7. Excited charmed mesons

    SciTech Connect

    Butler, J.N.; Shukla, S.

    1995-05-01

    The experimental status of excited charmed mesons is reviewed and is compared to theoretical expectations. Six states have been observed and their properties are consistent with those predicted for excited charmed states with orbital angular momentum equal to one.

  8. 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.

  9. Quasiparticles and Fermi liquid behaviour in an organic metal.

    PubMed

    Kiss, T; Chainani, A; Yamamoto, H M; Miyazaki, T; Akimoto, T; Shimojima, T; Ishizaka, K; Watanabe, S; Chen, C-T; Fukaya, A; Kato, R; Shin, S

    2012-01-01

    Many organic metals display exotic properties such as superconductivity, spin-charge separation and so on and have been described as quasi-one-dimensional Luttinger liquids. However, a genuine Fermi liquid behaviour with quasiparticles and Fermi surfaces have not been reported to date for any organic metal. Here, we report the experimental Fermi surface and band structure of an organic metal (BEDT-TTF)(3)Br(pBIB) obtained using angle-resolved photoelectron spectroscopy, and show its consistency with first-principles band structure calculations. Our results reveal a quasiparticle renormalization at low energy scales (effective mass m*=1.9 m(e)) and ω(2) dependence of the imaginary part of the self energy, limited by a kink at ~50 meV arising from coupling to molecular vibrations. The study unambiguously proves that (BEDT-TTF)(3)Br(pBIB) is a quasi-2D organic Fermi liquid with a Fermi surface consistent with Shubnikov-de Haas results. PMID:23011143

  10. RESONANT CAVITY EXCITATION SYSTEM

    DOEpatents

    Baker, W.R.

    1959-08-01

    A cavity excitation circuit is described for rapidly building up and maintaining high-level oscillations in a resonant cavity. The circuit overcomes oscillation buildup slowing effects such as ion locking in the cavity by providing for the selective application of an amplified accelerating drive signal to the main cavity exciting oscillator during oscillation buildup and a direct drive signal to the oscillator thereafter.

  11. 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

  12. 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.

  13. 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.

  14. Excited Charm States

    SciTech Connect

    Shukla, S.

    1994-12-31

    Characteristics of mass spectra and decays of orbitally excited charm mesons and baryons, expected on the basis of quark models and Heavy Quark Symmetry, are briefly described. The difficulties associated with measurements on these excited states are discussed. The accuracy and reliability of currently available experimental information is examined. The reasons, for the widely accepted spin-parity assignments to the observed excited mesons and baryons, are stated. Finally, the experimental data, with the accepted spin-parity assignments, is compared with expectations based on quark models and Heavy Quark Symmetry.

  15. 16. EXCITERS, AND SYNCHROSCOPE GAUGE ON WALL. ACTIVE ELECTRIC EXCITER ...

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

    16. EXCITERS, AND SYNCHROSCOPE GAUGE ON WALL. ACTIVE ELECTRIC EXCITER AT REAR; UNUSED WATER-DRIVEN EXCITER IN FOREGROUND. VIEW TO SOUTH-SOUTHWEST. - Santa Ana River Hydroelectric System, SAR-2 Powerhouse, Redlands, San Bernardino County, CA

  16. A Novel Liquid-Liquid Transition in Undercooled Ti-Zr-Ni Liquids

    NASA Technical Reports Server (NTRS)

    Lee, G. W.; Gangopadhyay, A. K.; Kelton, K. F.; Bradshaw, R. C.; Hyers, R. W.; Rathz, T. J.; Rogers, J. R.

    2004-01-01

    If crystallization can be avoided, liquids enter a metastable (undercooled) state below their equilibrium liquidus temperatures, T(sub l), finally 'freezing' into a glass below a characteristic temperature called the glass transition temperature, T(sub g). In rare cases, the undercooled liquid may undergo a liquid-liquid phase transition (liquid polymorphism) before entering the glassy state. This has been suggested from experimental studies of H2O and Si. Such phase transitions have been predicted in some stable liquids, ie. above T(sub l) at atmospheric pressure, for SiO2 and BeF2, but these have not been verified experimentally. They have been observed in liquids of P, Si and C, but only under high pressure. In this letter we present the first experimental evidence for a phase transition in a low viscosity metallic liquid that is driven by an approach to a constant entropy configuration state and correlated with a growing icosahedral order in the liquid. A maximum in the specific heat at constant pressure, similar to what is normally observed near T(sub g), is reported for undercooled liquids of quasicrystal-forming Ti-Zr-Ni alloys. A two-state excitation model that includes cooperativity by incorporating a temperature-dependent excitation energy, fits the specific heat data well, signaling a phase transition. An inflection in the liquid density with decreasing temperature instead of a discontinuity indicates that this is not a typical first order phase transition; it could be a weakly first order or higher order transition. While showing many similarities to a glass transition, this liquid-liquid phase transition occurs in a mobile liquid, making it novel.

  17. Geomagnetic excitation of nutation

    NASA Astrophysics Data System (ADS)

    Ron, C.; Vondrák, J.

    2015-08-01

    We tested the hypothesis of Malkin (2013), who demonstrated that the observed changes of Free Core Nutation parameters (phase, amplitude) occur near the epochs of geomagnetic jerks. We found that if the numerical integration of Brzeziński broad-band Liouville equations of atmospheric/oceanic excitations is re-initialized at the epochs of geomagnetic jerks, the agreement between the integrated and observed celestial pole offsets is improved (Vondrák & Ron, 2014). Nevertheless, this approach assumes that the influence of geomagnetic jerks leads to a stepwise change in the position of celestial pole, which is physically not acceptable. Therefore we introduce a simple continuous excitation function that hypothetically describes the influence of geomagnetic jerks, and leads to rapid but continuous changes of pole position. The results of numerical integration of atmospheric/oceanic excitations and this newly introduced excitation are then compared with the observed celestial pole offsets, and prove that the agreement is improved significantly.

  18. Sloshing motions in excited tanks

    NASA Astrophysics Data System (ADS)

    Frandsen, Jannette B.

    2004-05-01

    A fully non-linear finite difference model has been developed based on inviscid flow equations. Numerical experiments of sloshing wave motion are undertaken in a 2-D tank which is moved both horizontally and vertically. Results of liquid sloshing induced by harmonic base excitations are presented for small to steep non-breaking waves. The simulations are limited to a single water depth above the critical depth corresponding to a tank aspect ratio of hs/ b=0.5. The numerical model is valid for any water depth except for small depth when viscous effects would become important. Solutions are limited to steep non-overturning waves. Good agreement for small horizontal forcing amplitude is achieved between the numerical model and second order small perturbation theory. For large horizontal forcing, non-linear effects are captured by the third-order single modal solution and the fully non-linear numerical model. The agreement is in general good, both amplitude and phase. As expected, the third-order compared to the second-order solution is more accurate. This is especially true for resonance, high forcing frequency and mode interaction cases. However, it was found that multimodal approximate forms should be used for the cases in which detuning effects occur due to mode interaction. We present some test cases where detuning effects are evident both for single dominant modes and mode interaction cases. Furthermore, for very steep waves, just before the waves overturn, and for large forcing frequency, a discrepancy in amplitude and phase occurs between the approximate forms and the numerical model. The effects of the simultaneous vertical and horizontal excitations in comparison with the pure horizontal motion and pure vertical motion is examined. It is shown that vertical excitation causes the instability associated with parametric resonance of the combined motion for a certain set of frequencies and amplitudes of the vertical motion while the horizontal motion is related to classical resonance. It is also found that, in addition to the resonant frequency of the pure horizontal excitation, an infinite number of additional resonance frequencies exist due to the combined motion of the tank. The dependence of the non-linear behaviour of the solution on the wave steepness is discussed. It is found that for the present problem, non-linear effects become important when the steepness reaches about 0.1, in agreement with the physical experiments of Abramson [Rep. SP 106, NASA, 1966].

  19. 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.)

  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. Spin-Liquid State Study of Equilateral Triangle S=3/2 Spin Tubes Formed in CsCrF4

    NASA Astrophysics Data System (ADS)

    Manaka, Hirotaka; Hirai, Yuji; Hachigo, Yuta; Mitsunaga, Masahiro; Ito, Masakazu; Terada, Norio

    2009-09-01

    Topological effects on spin frustration in equilateral triangle S=3/2 spin tubes formed in CsCrF4 were studied by magnetic susceptibility, heat capacity [C(T)], and electron spin resonance experiments. The experimental data show that there is no magnetic long-range order down to T=1.3 K, and that no spin gap due to a chiral spin structure appears. Furthermore, since the C(T) curve has a T-linear component, a gapless spin-liquid ground state in one-dimensional antiferromagnets, the so-called Tomonaga-Luttinger liquid, is realized. This is characteristic of equilateral triangle spin tubes with S = half-integer.

  2. 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.

  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. Proteins of Excitable Membranes

    PubMed Central

    Nachmansohn, David

    1969-01-01

    Excitable membranes have the special ability of changing rapidly and reversibly their permeability to ions, thereby controlling the ion movements that carry the electric currents propagating nerve impulses. Acetylcholine (ACh) is the specific signal which is released by excitation and is recognized by a specific protein, the ACh-receptor; it induces a conformational change, triggering off a sequence of reactions resulting in increased permeability. The hydrolysis of ACh by ACh-esterase restores the barrier to ions. The enzymes hydrolyzing and forming ACh and the receptor protein are present in the various types of excitable membranes. Properties of the two proteins directly associated with electrical activity, receptor and esterase, will be described in this and subsequent lectures. ACh-esterase has been shown to be located within the excitable membranes. Potent enzyme inhibitors block electrical activity demonstrating the essential role in this function. The enzyme has been recently crystallized and some protein properties will be described. The monocellular electroplax preparation offers a uniquely favorable material for analyzing the properties of the ACh-receptor and its relation to function. The essential role of the receptor in electrical activity has been demonstrated with specific receptor inhibitors. Recent data show the basically similar role of ACh in the axonal and junctional membranes; the differences of electrical events and pharmacological actions are due to variations of shape, structural organization, and environment. PMID:19873642

  5. Superfluidity, BEC, and dimensions of liquid 4He in nanopores

    NASA Astrophysics Data System (ADS)

    Markić, L. Vranješ; Glyde, H. R.

    2015-08-01

    We present path integral Monte Carlo (PIMC) calculations of the superfluid fraction, ρS/ρ , and the one-body density matrix (OBDM) [Bose-Einstein condensation (BEC)] of liquid 4He confined in nanopores. Liquid 4He in nanopores represents a dense Bose liquid at reduced dimension and in disorder. The goal is to determine the effective dimensions of the liquid in the pores. It is to test whether observed properties, such as a very low onset temperature for superflow, Tc, can be predicted by a standard, static PIMC ρS/ρ . We simulate a cylinder of liquid of diameter dL surrounded by 5 Å of inert solid 4He in a nanopore of diameter d ; d =dL+10 Å . We find a PIMC ρS(T ) /ρ and OBDM that scales as a 1D fluid Luttinger liquid at extremely small liquid pore diameters only, dL=6 Å . At this dL, the liquid fills the pore in a 1D line at the center of the pore and there is no PIMC superflow. In the range 8 ≤dL≤22 Å the PIMC ρS(T ) /ρ scales as a 2D liquid. In this dL range the liquid fills the pores in 2D-like cylindrical layers. The crossover from no superflow at d =16 Å to superflow at d ≥18 Å agrees with experiment. There is a crossover to 3D scaling at larger dL≃22 Å . In the range 8 ≤dL≤22 Å , the Tc predicted using the Kosterlitz-Thouless 2D scaling criterion of the OBDM agrees well with that obtained from ρS(T ) /ρ . These results suggest that the superflow observed in small pore media is standard static superflow with the low Tc arising from its 2D character. An operational onset temperature, TBEC, for BEC can be defined as the temperature at which there is a crossover from exponential to algebraic decay in the OBDM. This definition leads to a TBEC≥Tc as observed in larger pore media.

  6. Excited species in the FBX dosimeter system

    NASA Astrophysics Data System (ADS)

    Gupta, B. L.

    2003-08-01

    In the FBX dosimeter solution, the excitation of xylenol orange (XO) produces maximum emission at 550-575 nm both at room and liquid nitrogen temperatures (about 85%) having a lifetime of 0.20-0.36 ns. In addition, at room temperature there is an emission at 350 nm for the excitation at 260 nm (about 15%) having a longer lifetime of 3.71-4.01 ns. Benzoic acid (BA) has excitation at 284-295 nm and emission at 320-365 nm having a lifetime of 1.38 ns. In an aqueous solution containing 5×10 -3 mol dm -3 BA, 2×10 -4 mol dm -3 XO and 0.04 mol dm -3 H 2SO 4 there is no XO emission at 550 nm due to UV absorption at 260 nm by BA. In this solution, 2 emissions are observed near 350-360 nm, having lifetimes of 1.25 ns (89%) and 2.86 ns (11%). The wavelengths for the emission of XO and absorption of ferric-XO complex are nearly the same. Excited XO produces oxidation of ferrous ions and BA increases the chain length.

  7. Virtual network as excitable medium

    NASA Astrophysics Data System (ADS)

    Shinyaeva, Taisiya S.; Tarasevich, Yuri Yu.

    2016-02-01

    We simulated the spread of an activity in a virtual group using the model of excitable medium. We assumed that the structure of the virtual group corresponds to a scale- free network. In our simulation, the network consists of 100 nodes, the average degree of the nodes is 1.98. We considered the propagation of excitation both in a homogeneous and an inhomogeneous excitable medium. The simulation showed that the initial conditions have a little effect on the behaviour of the model. In inhomogeneous medium, fraction of the excited nodes increases, when permanent excited elements (‘active’ centres) appear in the network. The fraction of the excited nodes increases, when we increase the number of the permanent excited elements. Locations of the active centres do not affect at the level of excitation. External source of activator increases the fraction of the excited nodes in the scale-free network with distribution of parameters.

  8. Aperture excited dielectric antennas

    NASA Technical Reports Server (NTRS)

    Crosswell, W. F.; Chatterjee, J. S.; Mason, V. B.; Tai, C. T.

    1974-01-01

    The results of a comprehensive experimental and theoretical study of the effect of placing dielectric objects over the aperture of waveguide antennas are presented. Experimental measurements of the radiation patterns, gain, impedance, near-field amplitude, and pattern and impedance coupling between pairs of antennas are given for various Plexiglas shapes, including the sphere and the cube, excited by rectangular, circular, and square waveguide feed apertures. The waveguide excitation of a dielectric sphere is modeled using the Huygens' source, and expressions for the resulting electric fields, directivity, and efficiency are derived. Calculations using this model show good overall agreement with experimental patterns and directivity measurements. The waveguide under an infinite dielectric slab is used as an impedance model. Calculations using this model agree qualitatively with the measured impedance data. It is concluded that dielectric loaded antennas such as the waveguide excited sphere, cube, or sphere-cylinder can produce directivities in excess of that obtained by a uniformly illuminated aperture of the same cross section, particularly for dielectric objects with dimensions of 2 wavelengths or less. It is also shown that for certain configurations coupling between two antennas of this type is less than that for the same antennas without dielectric loading.

  9. Nonlinear excitations in lattices

    NASA Astrophysics Data System (ADS)

    Zhou, Jun

    We analyze some of the properties of nonlinear excitations occurring in lattices such as polarons, bipolarons or discrete breathers (DBs). While polarons and bipolarons are the result of the self-trapping of one or two electronic carriers by the lattice distortion they generate, DBs occur in networks of identical non-harmonic oscillators as exact solutions to the equations of motion that are both time-periodic and spatially localized. In certain limits, these excitations may be described by a common class of models: the Discrete Nonlinear Schrodinger Equation and its generalizations. We first use an exact perturbative expansion to derive the bipolaronic phase diagram of the 1D adiabatic Holstein-Hubbard model (HH) in the strong coupling limit. In the second part of the thesis we study DBs on d-dimensional cubic lattices with arbitrary power nonlinearity. We compare the exact results to an exponential ansatz approach and to the solution to the Single Nonlinear Impurity (SNI) model. We show that DB excitation thresholds can be evaluated explicitly in the limit of high nonlinearity, and we prove a conjecture by Bustamante and Molina [PRB 62, 15287 (2000)] that the limiting value of the SNI bound state energy is universal as the nonlinearity tends to infinity.

  10. 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.

  11. 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.

  12. Wigner crystallization of single photons in cold Rydberg ensembles.

    PubMed

    Otterbach, Johannes; Moos, Matthias; Muth, Dominik; Fleischhauer, Michael

    2013-09-13

    The coupling of weak light fields to Rydberg states of atoms under conditions of electromagnetically induced transparency leads to the formation of Rydberg polaritons which are quasiparticles with tunable effective mass and nonlocal interactions. Confined to one spatial dimension their low energy physics is that of a moving-frame Luttinger liquid which, due to the nonlocal character of the repulsive interaction, can form a Wigner crystal of individual photons. We calculate the Luttinger K parameter using density-matrix renormalization group simulations and find that under typical slow-light conditions kinetic energy contributions are too strong for crystal formation. However, adiabatically increasing the polariton mass by turning a light pulse into stationary spin excitations allows us to generate true crystalline order over a finite length. The dynamics of this process and asymptotic correlations are analyzed in terms of a time-dependent Luttinger theory. PMID:24074081

  13. Resonance Pacemakers in Excitable Media

    NASA Astrophysics Data System (ADS)

    Chigwada, Tabitha Ruvarashe; Parmananda, P.; Showalter, Kenneth

    2006-06-01

    Chemical waves are initiated in an excitable medium by resonance with local periodic forcing of the excitability. Experiments are carried out with a photosensitive Belousov-Zhabotinsky medium, in which the excitability is varied according to the intensity of the imposed illumination. Complex resonance patterns are exhibited as a function of the amplitude and frequency of the forcing. Local resonance-induced wave initiation transforms the medium globally from a quiescent excitable steady state to a periodic state of successive traveling waves.

  14. 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

  15. 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

  16. A Liquid-Liquid Transition in an Undercooled Ti-Zr-Ni Liquid

    NASA Technical Reports Server (NTRS)

    Lee, G. W.; Gangopadhyay, A. K.; Kelton, K. F.; Hyers, R. W.; Rathz, T. J.; Rogers, J. R.

    2003-01-01

    If crystallization can be avoided, liquids enter a metastable (undercooled) state below their equilibrium liquidus temperatures, TI, finally freezing into a glass below a characteristic temperature called the glass transition temperature, T,. In rare cases, the undercooled liquid may undergo a liquid-liquid phase transition (liquid polymorphism) before entering the glassy state. This has been suggested from experimental studies of HzO and Si4. Such phase transitions have been predicted in some stable liquids, i.e. above TI at atmospheric pressure, for Si02 and BeF;, but these have not been verified experimentally. They have been observed in liquids of P7, Sis and C9, but only under high pressure. All of these transitions are driven by an anomalous density change, i.e. change in local structure, with temperature or pressure. In this letter we present the first experimental evidence for a phase transition in a low viscosity liquid that is not driven by an anomalous density change, but by an approach to a constant configuration state. A maximum in the specific heat at constant pressure, similar to what is normally observed near T,, is reported here for undercooled low viscosity liquids of quasicrystal- forming Ti-Zr-Ni alloys. that includes cooperativity, by incorporating a temperature dependent excitation energy fits the data well, signaling a phase transition.

  17. Search for Gluonic Excitations

    SciTech Connect

    Paul Eugenio

    2007-10-01

    Studies of meson spectra via strong decays provide insight regarding QCD at the confinement scale. These studies have led to phenomenological models for QCD such as the constituent quark model. However, QCD allows for a much richer spectrum of meson states which include extra states such as exotics, hybrids, multi-quarks, and glueballs. First discussion of the status of exotic meson searches is given followed by a discussion of plans at Jefferson Lab to double the energy of the machine to 12 GeV, which will allow us to access photoproduction of mesons in search for gluonic excited states.

  18. Search for Gluonic Excitations

    SciTech Connect

    Eugenio, Paul

    2007-10-26

    Studies of meson spectra via strong decays provide insight regarding QCD at the confinement scale. These studies have led to phenomenological models for QCD such as the constituent quark model. However, QCD allows for a much richer spectrum of meson states which include extra states such as exotics, hybrids, multi-quarks, and glueballs. First discussion of the status of exotic meson searches is given followed by a discussion of plans at Jefferson Lab to double the energy of the machine to 12 GeV, which will allow us to access photoproduction of mesons in search for gluonic excited states.

  19. SHOCK-EXCITED OSCILLATOR

    DOEpatents

    Creveling, R.

    1957-12-17

    S> A shock-excited quartz crystal oscillator is described. The circuit was specifically designed for application in micro-time measuring work to provide an oscillator which immediately goes into oscillation upon receipt of a trigger pulse and abruptly ceases oscillation when a second pulse is received. To achieve the instant action, the crystal has a prestressing voltage applied across it. A monostable multivibrator receives the on and off trigger pulses and discharges a pulse through the crystal to initiate or terminate oscillation instantly.

  20. Excited state optical modulator

    SciTech Connect

    Ebbesen, T.W.

    1986-07-01

    It is shown that if two light beams intersect in a medium containing the appropriate molecule, one beam can modulate the other by making use of the differences in the absorption spectra of the ground and excited molecular states. This is possible even with the power of semiconductor lasers. From this, an opto-optical modulating device can be conceived which would have micrometer dimensions, potentially fast response time, and significant quantum gain. Such a device could find use in optical communications and optical computing.

  1. 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.

  2. Composite fermion excitations in fractional quantum Hall systems

    SciTech Connect

    Quinn, J.J.

    1995-04-01

    In two dimensional systems in a strong magnetic field, electrons can be transformed into composite Fermions (CF) by attaching to each a fictitious flux tube (carrying flux {Phi}) and fictitious charge q, where the product q{sup {Phi}} is a multiple of 2 {Pi}. In the mean field approximation, this transformation converts a fractionally filled electron Landau level into an integrally filled CF Landau level. This integrally filled CF Landau level corresponds to the ground state of a Laughlin incompressible fluid. Excited states are described by the n{sub QE} and n{sub QH}, the numbers of quasielectron and quasihole CF excitations. For N electrons on the surface of a sphere the energy and angular momentum of a quasihole (or quasielectron) are {var_epsilon}{sub QH} and l{sub QH}=1/2(N+n{sub QH}-n{sub QE}-1) (or {var_epsilon}{sub QE} and l{sub QE}=l{sub QH}+1). The lowest energy sector of the energy spectrum contains the minimum number of CF excitations consistent with the value of N and the degeneracy of the lowest Landau level, 2S+1. The first excited sector contains one additional QE-QH pair. The total angular momentum L is obtained by adding the angular momenta of QE excitations and QH excitations treated as distinguished sets of Fermions. In the absence of CF interactions, all states containing n{sub QE} quasielectrons and n{sub QH} quasiholes are degenerate. The interaction between CF excitations partially removes this degeneracy. The interactions between CF excitations can be determined by comparing exact numerical results for N electrons with the CF picture. This amounts to constructing a Fermi liquid theory of CF excitations, and should allow the study of low lying excitations of systems with much larger values of N than can be treated numerically.

  3. Formation and Observation of a Quasi-Two-Dimensional dxy Electron Liquid in Epitaxially Stabilized Sr(2-x)La(x)TiO4 Thin Films.

    PubMed

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

    2015-08-28

    We report the formation and observation of an electron liquid in Sr(2-x)La(x)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 3d_{xy} 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. PMID:26371669

  4. Fluorescent optical liquid level sensor

    DOEpatents

    Weiss, Jonathan D. (Albuquerque, NM)

    2001-01-01

    A liquid level sensor comprising a transparent waveguide containing fluorescent material that is excited by light of a first wavelength and emits at a second, longer wavelength. The upper end of the waveguide is connected to a light source at the first wavelength through a beveled portion of the waveguide such that the input light is totally internally reflected within the waveguide above an air/liquid interface in a tank but is transmitted into the liquid below this interface. Light is emitted from the fluorescent material only in those portions of the waveguide that are above the air/liquid interface, to be collected at the upper end of the waveguide by a detector that is sensitive only to the second wavelength. As the interface moves down in the tank, the signal strength from the detector will increase.

  5. 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.

  6. 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.}

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

    NASA Astrophysics Data System (ADS)

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

    2016-01-01

    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.

  8. LSPR properties of metal nanoparticles adsorbed at a liquid-liquid interface.

    PubMed

    Yang, Zhilin; Chen, Shu; Fang, Pingping; Ren, Bin; Girault, Hubert H; Tian, Zhongqun

    2013-04-21

    Unlike the solid-air and solid-liquid interfaces, the optical properties of metal nanoparticles adsorbed at the liquid-liquid interface have not been theoretically exploited to date. In this work, the three dimensional finite difference time domain (3D-FDTD) method is employed to clarify the localized surface plasmon resonance (LSPR) based optical properties of gold nanoparticles (NPs) adsorbed at the water-oil interface, including near field distribution, far field absorption and their relevance. The LSPR spectra of NPs located at a liquid-liquid interface are shown to differ significantly from those in a uniform liquid environment or at the other interfaces. The absorption spectra exhibit two distinct LSPR peaks, the positions and relative strengths of which are sensitive to the dielectric properties of each liquid and the exact positions of the NPs with respect to the interface. Precise control of the particles' position and selection of the appropriate wavelength of the excitation laser facilitates the rational design and selective excitation of localized plasmon modes for interfacial NPs, a necessary advance for the exploration of liquid-liquid interfaces via surface enhanced Raman spectroscopy (SERS). According to our calculations, the SERS enhancement factor for Au nanosphere dimers at the water-oil interface can be as high as 10(7)-10(9), implying significant promise for future investigations of interfacial structure and applications of liquid-liquid interfaces towards chemical analysis. PMID:23376970

  9. Collective excitations in soft-sphere fluids

    NASA Astrophysics Data System (ADS)

    Bryk, Taras; Gorelli, Federico; Ruocco, Giancarlo; Santoro, Mario; Scopigno, Tullio

    2014-10-01

    Despite that the thermodynamic distinction between a liquid and the corresponding gas ceases to exist at the critical point, it has been recently shown that reminiscence of gaslike and liquidlike behavior can be identified in the supercritical fluid region, encoded in the behavior of hypersonic waves dispersion. By using a combination of molecular dynamics simulations and calculations within the approach of generalized collective modes, we provide an accurate determination of the dispersion of longitudinal and transverse collective excitations in soft-sphere fluids. Specifically, we address the decreasing rigidity upon density reduction along an isothermal line, showing that the positive sound dispersion, an excess of sound velocity over the hydrodynamic limit typical for dense liquids, displays a nonmonotonic density dependence strictly correlated to that of thermal diffusivity and kinematic viscosity. This allows rationalizing recent observation parting the supercritical state based on the Widom line, i.e., the extension of the coexistence line. Remarkably, we show here that the extremals of transport properties such as thermal diffusivity and kinematic viscosity provide a robust definition for the boundary between liquidlike and gaslike regions, even in those systems without a liquid-gas binodal line. Finally, we discuss these findings in comparison with recent results for Lennard-Jones model fluid and with the notion of the "rigid-nonrigid" fluid separation lines.

  10. Collective excitations in soft-sphere fluids.

    PubMed

    Bryk, Taras; Gorelli, Federico; Ruocco, Giancarlo; Santoro, Mario; Scopigno, Tullio

    2014-10-01

    Despite that the thermodynamic distinction between a liquid and the corresponding gas ceases to exist at the critical point, it has been recently shown that reminiscence of gaslike and liquidlike behavior can be identified in the supercritical fluid region, encoded in the behavior of hypersonic waves dispersion. By using a combination of molecular dynamics simulations and calculations within the approach of generalized collective modes, we provide an accurate determination of the dispersion of longitudinal and transverse collective excitations in soft-sphere fluids. Specifically, we address the decreasing rigidity upon density reduction along an isothermal line, showing that the positive sound dispersion, an excess of sound velocity over the hydrodynamic limit typical for dense liquids, displays a nonmonotonic density dependence strictly correlated to that of thermal diffusivity and kinematic viscosity. This allows rationalizing recent observation parting the supercritical state based on the Widom line, i.e., the extension of the coexistence line. Remarkably, we show here that the extremals of transport properties such as thermal diffusivity and kinematic viscosity provide a robust definition for the boundary between liquidlike and gaslike regions, even in those systems without a liquid-gas binodal line. Finally, we discuss these findings in comparison with recent results for Lennard-Jones model fluid and with the notion of the "rigid-nonrigid" fluid separation lines. PMID:25375488

  11. Multiphoton excitation of organic chromophores in microbubble resonators

    NASA Astrophysics Data System (ADS)

    Cohoon, Gregory A.; Kieu, Khanh; Norwood, Robert A.

    2014-03-01

    We report the observation of multiphoton excitation of organic chromophores in microbubble whispering gallery mode resonators. High-Q microbubble resonators are a formed by heating a pressurized fused silica capillary to form a hollow bubble which can be filled with liquid. In this case, the microbubble is filled with a solution of Rhodamine 6G dye. The resonator and dye are excited by evanescently coupling CW light from a 980nm laser diode using a tapered optical fiber. The two-photon fluorescence of the dye can be seen with pump powers as low as 1 mW.

  12. 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.

  13. Fission fragment excited laser system

    DOEpatents

    McArthur, David A.; Tollefsrud, Philip B.

    1976-01-01

    A laser system and method for exciting lasing action in a molecular gas lasing medium which includes cooling the lasing medium to a temperature below about 150 K and injecting fission fragments through the lasing medium so as to preferentially excite low lying vibrational levels of the medium and to cause population inversions therein. The cooled gas lasing medium should have a mass areal density of about 5 .times. 10.sup.-.sup.3 grams/square centimeter, relaxation times of greater than 50 microseconds, and a broad range of excitable vibrational levels which are excitable by molecular collisions.

  14. LIQUID TARGET

    DOEpatents

    Martin, M.D.; Salsig, W.W. Jr.

    1959-01-13

    A liquid handling apparatus is presented for a liquid material which is to be irradiated. The apparatus consists essentially of a reservoir for the liquid, a target element, a drain tank and a drain lock chamber. The target is in the form of a looped tube, the upper end of which is adapted to be disposed in a beam of atomic particles. The lower end of the target tube is in communication with the liquid in the reservoir and a means is provided to continuously circulate the liquid material to be irradiated through the target tube. Means to heat the reservoir tank is provided in the event that a metal is to be used as the target material. The apparatus is provided with suitable valves and shielding to provide maximum safety in operation.

  15. 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.

  16. Algebraic spin liquid in an exactly solvable spin model

    SciTech Connect

    Yao, Hong; Zhang, Shou-Cheng; Kivelson, Steven A.; /Stanford U., Phys. Dept.

    2010-03-25

    We have proposed an exactly solvable quantum spin-3/2 model on a square lattice. Its ground state is a quantum spin liquid with a half integer spin per unit cell. The fermionic excitations are gapless with a linear dispersion, while the topological 'vison' excitations are gapped. Moreover, the massless Dirac fermions are stable. Thus, this model is, to the best of our knowledge, the first exactly solvable model of half-integer spins whose ground state is an 'algebraic spin liquid.'

  17. Search for extended-lifetime optically excited laser media

    NASA Astrophysics Data System (ADS)

    Pummer, H.; Egger, H.

    Optical excited cryogenic rare gas fluorine solutions indicate an efficient two step, one photon channel into several excited dimer and trimer states. The excitation is sensitive to the pump wavelength with respect to the excitation efficiency and the type of excited state obtained. The excited states radiate on several B-X, C-A, D-X dimer and GAMMA-GAMMA trimer transitions. The trimer transitions were assigned to (6(2)GAMMA - 1,2(2)GAMMA) and (4(2)GAMMA - 1,2(2)GAMMA) where the upper state can be formed by a clustering reaction involving the D and B-state of the dimer, respectively. In pure Xe(F2) solutions, the stability of the D and B-dimer states is questionable. Theoretical Xe2F* potential energy curves indicate that, at high Xe densities, theses dimer states should collapse into the 6(2)GAMMA and 4(2)GAMMER Xe2F* trimer states, respectively. Lifetimes as great as 50 nsec in the liquid environment are observed. All emissions are observed red shifted with respect to the gas phase values, and shifts of up to 0.9 eV in magnitude have been observed for the D-X transition in XeF.

  18. Topological excitations in magnetic materials

    NASA Astrophysics Data System (ADS)

    Bazeia, D.; Doria, M. M.; Rodrigues, E. I. B.

    2016-05-01

    In this work we propose a new route to describe topological excitations in magnetic systems through a single real scalar field. We show here that spherically symmetric structures in two spatial dimensions, which map helical excitations in magnetic materials, admit this formulation and can be used to model skyrmion-like structures in magnetic materials.

  19. Attosecond photoscopy of plasmonic excitations.

    PubMed

    Lupetti, Mattia; Hengster, Julia; Uphues, Thorsten; Scrinzi, Armin

    2014-09-12

    We propose an experimental arrangement to image, with attosecond resolution, transient surface plasmonic excitations. The required modifications to state-of-the-art setups used for attosecond streaking experiments from solid surfaces only involve available technology. Buildup and lifetimes of surface plasmon polaritons can be extracted and local modulations of the exciting optical pulse can be diagnosed in situ. PMID:25259981

  20. 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.

  1. Liquid penetrants

    NASA Technical Reports Server (NTRS)

    Pasley, R. L.

    1973-01-01

    Liquid-penetrant inspection is discussed for surface defects in solids. The principle advantages are considered to be its simplicity and economy. The techniques and penetrants are described along with the developers. Commercially available equipment is also described.

  2. All-optical excitation and detection of leaky Rayleigh waves.

    PubMed

    Desmet, C; Gusev, V; Lauriks, W; Glorieux, C; Thoen, J

    1997-01-15

    The results of experiments on all-optical monitoring of leaky Rayleigh waves are reported. Leaky Rayleigh waves were excited by pulsed laser action on a liquid-solid interface and were detected by the light-beam-deflection technique. Both the measured velocity of their propagation and the attenuation are in good agreement with theoretical predictions. Possible applications include acoustic spectroscopy of materials, depth profiling of layered structures, and tabletop modeling of seismic phenomena. PMID:18183105

  3. Selective multiphoton excitation by parametrically shaped laser pulses

    NASA Astrophysics Data System (ADS)

    Lindinger, A.

    2015-05-01

    Laser pulse shaping is reported for applications on multiphoton processes in dye molecules. Particularly phase-tailored pulse shapes are employed for two-photon excited fluorescence of dyes in a liquid environment, also at the distal end of an optical fiber, in order to improve the contrast between dye markers having similar excitation spectra. Precompensation of the optical fiber properties is utilized by analytical pulse shaping in order to receive specific parametric pulse forms after the fiber. This will lead to new endoscopic imaging applications with an increased fluorescence contrast. Moreover, selective excitation is also demonstrated for three-photon transitions of the two dyes, p-Terphenyl (PTP) and BM-Terphenyl (BMT), in solution by using shaped pulses without a fiber. A good agreement between experiment and theoretical simulation is obtained. With this approach it is possible to achieve a considerable change of the fluorescence contrast between the two dyes which is relevant for imaging applications of biological molecules.

  4. Dynamic behavior of liquid free surface in a cylindrical container subject to vertical vibration

    NASA Astrophysics Data System (ADS)

    Hashimoto, H.; Sudo, S.

    1984-05-01

    This paper reports a series of experimental studies on the dynamic behavior of the gas-liquid interface. These studies are concerned with the liquid sloshing phenomena induced by vertical vibration of a cylindrical container containing a liquid. The disappearance of the harmonic surface wave motion, the formation of 1/2-subharmonic motion, the mechanism of the surface disintegration and the behavior of spray-excited low frequency waves are investigated. The effect of the liquid height in the container on the surface disintegration was a decrease in the threshold excitation amplitude for the disintegration with an increase in liquid height. Spray-excited low frequency waves were observed over a wide range of excitation frequencies. It was also found that a violet surface agitation might occur due to a bubble cluster formed by the air injection, although the excitation acceleration was relatively low.

  5. 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.

  6. 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.

  7. 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.

  8. Collisional excitation of interstellar formaldehyde

    NASA Technical Reports Server (NTRS)

    Green, S.; Garrison, B. J.; Lester, W. A., Jr.; Miller, W. H.

    1978-01-01

    Previous calculations for rates of excitation of ortho-H2CO by collisions with He have been extended to higher rotational levels and kinetic temperatures to 80 K. Rates for para-H2CO have also been computed. Pressure-broadening widths for several spectral lines have been obtained from these calculations and are found to agree with recent data within the experimental uncertainty of 10%. Excitation of formaldehyde by collisions with H2 molecules is also discussed.

  9. 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

  10. 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.

  11. 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.

  12. Pulse Excitation Method of Coherent-Population-Trapping Suitable for Chip-Scale Atomic Clock

    NASA Astrophysics Data System (ADS)

    Yano, Yuichiro; Goka, Shigeyoshi

    2012-12-01

    We propose a pulse excitation method of coherent population trapping (CPT) with a liquid crystal optical modulator. Since liquid crystals enable reductions in size, weight, cost, and power consumption compared with acousto-optical modulators (AOMs), our method is suitable for chip-scale atomic clocks (CSACs). Experiments showed that pulse excitation with a liquid crystal modulator can narrow the CPT resonance linewidth and reduce the light shift effect using a 87Rb gas cell and the D1-line vertical-cavity surface-emitting laser (VCSEL). The CPT resonance linewidth and light shift sensitivity were less than one-eighth and one-third those for continuous excitation, respectively. They also showed that our method is comparable to that based on an AOM.

  13. Vacuum ultraviolet electronic properties of liquids

    SciTech Connect

    Painter, L.R.

    1989-01-01

    The principal aim of this program has been to study the electronic structure of insulating liquids of biological interest over a broad energy range from 0 to 30 eV. The studies basically consist of measuring the reflectance, transmittance, photoemission and photoionization of dielectric liquids in the vacuum ultraviolet spectral region as a function of angle of incidence and energy. these in turn may be interpreted in terms of the electronic structure of each liquid as it is excited by the passage of a charged particle. Optical data provides indirect evidence that collective effects occur in liquids. Direct observation of their existence is substantiated in studies of the energy distribution of electrons specularly scattered from the liquid surface.

  14. Two-component Fermi-liquid theory - Equilibrium properties of liquid metallic hydrogen

    NASA Technical Reports Server (NTRS)

    Oliva, J.; Ashcroft, N. W.

    1981-01-01

    It is reported that the transition of condensed hydrogen from an insulating molecular crystal phase to a metallic liquid phase, at zero temperature and high pressure, appears possible. Liquid metallic hydrogen (LMH), comprising interpenetrating proton and electron fluids, would constitute a two-component Fermi liquid with both a very high component-mass ratio and long-range, species-dependent bare interactions. The low-temperature equilibrium properties of LMH are examined by means of a generalization to the case of two components of the phenomenological Landau Fermi-liquid theory, and the low-temperature specific heat, compressibility, thermal expansion coefficient and spin susceptibility are given. It is found that the specific heat and the thermal expansion coefficient are vastly greater in the liquid than in the corresponding solid, due to the presence of proton quasiparticle excitations in the liquid.

  15. 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

  16. Sadomasochism, sexual excitement, and perversion.

    PubMed

    Kernberg, O F

    1991-01-01

    Sadomasochism, an ingredient of infantile sexuality, is an essential part of normal sexual functioning and love relations, and of the very nature of sexual excitement. Sadomasochistic elements are also present in all sexual perversions. Sadomasochism starts out as the potential for erotic masochism in both sexes, and represents a very early capacity to link aggression with the libidinal elements of sexual excitement. Sexual excitement may be considered a basic affect that overcomes primitive splitting of love and hatred. Erotic desire is a more mature form of sexual excitement. Psychoanalytic exploration makes it possible to uncover the unconscious components of sexual excitement: wishes for symbiotic fusion and for aggressive penetration and intermingling; bisexual identifications; the desire to transgress oedipal prohibitions and the secretiveness of the primal scene, and to violate the boundaries of a teasing and withholding object. The relation between these wishes and the development of erotic idealization processes in both sexes is explored in the context of a critical review of the pertinent psychoanalytic literature. PMID:1856437

  17. 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

  18. 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.

  19. Modeling excitable systems: Reentrant tachycardia

    NASA Astrophysics Data System (ADS)

    Lancaster, Jarrett L.; Hellen, Edward H.; Leise, Esther M.

    2010-01-01

    Excitable membranes are an important type of nonlinear dynamical system, and their study can be used to provide a connection between physical and biological circuits. We discuss two models of excitable membranes important in cardiac and neural tissues. One model is based on the Fitzhugh-Nagumo equations, and the other is based on a three-transistor excitable circuit. We construct a circuit that simulates reentrant tachycardia and its treatment by surgical ablation. This project is appropriate for advanced undergraduates as a laboratory capstone project or as a senior thesis or honors project and can also be a collaborative project, with one student responsible for the computational predictions and another for the circuit construction and measurements.

  20. Indirect excitation of ultrafast demagnetization

    PubMed Central

    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

  1. Indirect excitation of ultrafast demagnetization

    DOE PAGESBeta

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

    2016-01-06

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

  2. Indirect excitation of ultrafast demagnetization

    NASA Astrophysics Data System (ADS)

    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.

  3. Stochastic excitation of stellar oscillations

    NASA Astrophysics Data System (ADS)

    Samadi, Reza

    2001-05-01

    Since more than about thirty years, solar oscillations are thought to be excited stochastically by the turbulent motions in the solar convective zone. It is currently believed that oscillations of stars lower than 2 solar masses - which possess an upper convective zone - are excited stochastically by turbulent convection in their outer layers. Providing that accurate measurements of the oscillation amplitudes and damping rates are available it is possible to evaluate the power injected into the modes and thus - by comparison with the observations - to constrain current theories. A recent theoretical work (Samadi & Goupil, 2001; Samadi et al., 2001) supplements and reinforces the theory of stochastic excitation of star vibrations. This process was generalized to a global description of the turbulent state of their convective zone. The comparison between observation and theory, thus generalized, will allow to better know the turbulent spectrum of stars, and this in particular thanks to the COROT mission.

  4. 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

  5. Rocking response of tanks containing two liquids

    SciTech Connect

    Tang, Yu; Chang, Y.W.

    1993-06-01

    Liquid storage tanks are important components of industrial facilities and, when located in earthquake prone regions, should be designed to withstand the earthquakes to which they may be subjected. There are cases in which the density of the tank content is not uniform. For such cases, the dynamic responses of tanks containing liquids with different densities must be studied. A study on the dynamic response of upright circular cylindrical liquid-storage tanks containing two different liquids under a rock base motion with an arbitrary temporal variation is presented. Only rigid tanks were studied. The response quantities examined include the hydrodynamic pressure, sloshing wave height and the associated frequencies, base shear and moments. Each of these response quantities is expressed as the sum of the so-called impulsive component and convective component. Unlike the case of tanks containing one liquid, in which the response is controlled by one parameter, height-to-radius ratio, the response of tanks containing two different liquids are controlled by three parameters: height-to-radius ratio, and mass density ratio and height ratio of the two liquids. The interrelationship of the responses of the tank-liquid system to rocking and lateral base excitations is established by examining numerical results extensively. It is found that some of the response quantities for a tank-liquid system under a rocking base motion can be determined from the corresponding response quantities for an identical tank under a horizontal base motion.

  6. Calculation of molecular excitation rates

    NASA Technical Reports Server (NTRS)

    Flynn, George

    1993-01-01

    State-to-state collisional excitation rates for interstellar molecules observed by radio astronomers continue to be required to interpret observed line intensities in terms of local temperatures and densities. A problem of particular interest is collisional excitation of water which is important for modeling the observed interstellar masers. In earlier work supported by a different NASA Grant, excitation of water in collisions with He atoms was studied; after many years of successively more refined calculations that problem now seems to be well understood, and discrepancies with earlier experimental data for related (pressure broadening) phenomena are believed to reflect experimental errors. Because of interstellar abundances, excitation by H2, the dominant interstellar species, is much more important than excitation by He, although it has been argued that rates for excitation by these are similar. Under the current grant theoretical study of this problem has begun which is greatly complicated by the additional degrees of freedom which must be included both in determining the interaction potential and also in the molecular scattering calculation. We have now computed the interaction forces for nearly a thousand molecular geometries and are close to having an acceptable global fit to these points which is necessary for the molecular dynamics calculations. Also, extensive modifications have been made to the molecular scattering code, MOLSCAT. These included coding the rotational basis sets and coupling matrix elements required for collisions of an asymmetric top with a linear rotor. A new method for numerical solution of the coupled equations has been incorporated. Because of the long-ranged nature of the water-hydrogen interaction it is necessary to integrate the equations to rather large intermolecular separations, and the integration methods previously available in MOLSCAT are not ideal for such cases. However, the method used by Alexander in his HIBRIDON code is particularly suited for such cases. We have obtained this code and incorporated that part which solves the coupled differential equations as an option in the MOLSCAT program.

  7. Liquid-liquid driven cavity flow

    SciTech Connect

    Mansell, G.; Walter, J.; Marschall, E. )

    1994-02-01

    Liquid-liquid driven cavity flow was studied numerically. Information on [open quotes]realistic[close quotes] liquid-liquid interface conditions were obtained from photochromic flow visualization experiments. With this input, numerically obtained flow fields agreed well with experimentally observed flow fields. A parametric numerical study showed the influence of various parameters on the behavior of interface velocity and tangential shear stress gradient in the vicinity of the liquid-liquid interface. 24 refs., 16 figs.

  8. 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...

  9. 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...

  10. 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...

  11. 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...

  12. 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...

  13. Autoresonant Excitation of Antiproton Plasmas

    SciTech Connect

    Andresen, G. B.; Bowe, P. D.; Hangst, J. S.; Ashkezari, M. D.; Hayden, M. E.; Baquero-Ruiz, M.; Chapman, S.; Fajans, J.; Povilus, A.; So, C.; Bertsche, W.; Butler, E.; Charlton, M.; Humphries, A. J.; Madsen, N.; Werf, D. P. van der; Carpenter, P. T.; Hurt, J. L.; Robicheaux, F.; Cesar, C. L.

    2011-01-14

    We demonstrate controllable excitation of the center-of-mass longitudinal motion of a thermal antiproton plasma using a swept-frequency autoresonant drive. When the plasma is cold, dense, and highly collective in nature, we observe that the entire system behaves as a single-particle nonlinear oscillator, as predicted by a recent theory. In contrast, only a fraction of the antiprotons in a warm plasma can be similarly excited. Antihydrogen was produced and trapped by using this technique to drive antiprotons into a positron plasma, thereby initiating atomic recombination.

  14. Autoresonant excitation of antiproton plasmas.

    PubMed

    Andresen, G B; Ashkezari, M D; Baquero-Ruiz, M; Bertsche, W; Bowe, P D; Butler, E; Carpenter, P T; Cesar, C L; Chapman, S; Charlton, M; Fajans, J; Friesen, T; Fujiwara, M C; Gill, D R; Hangst, J S; Hardy, W N; Hayden, M E; Humphries, A J; Hurt, J L; Hydomako, R; Jonsell, S; Madsen, N; Menary, S; Nolan, P; Olchanski, K; Olin, A; Povilus, A; Pusa, P; Robicheaux, F; Sarid, E; Silveira, D M; So, C; Storey, J W; Thompson, R I; van der Werf, D P; Wurtele, J S; Yamazaki, Y

    2011-01-14

    We demonstrate controllable excitation of the center-of-mass longitudinal motion of a thermal antiproton plasma using a swept-frequency autoresonant drive. When the plasma is cold, dense, and highly collective in nature, we observe that the entire system behaves as a single-particle nonlinear oscillator, as predicted by a recent theory. In contrast, only a fraction of the antiprotons in a warm plasma can be similarly excited. Antihydrogen was produced and trapped by using this technique to drive antiprotons into a positron plasma, thereby initiating atomic recombination. PMID:21405235

  15. 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.

  16. Chiral liquids

    NASA Astrophysics Data System (ADS)

    Zakharov, V. I.

    2015-05-01

    We review briefly properties of chiral liquids, or liquids with massless fermionic constituents. We concentrate on three effects, namely, the low ratio of viscosity η to entropy density s, chiral magnetic and vortical effects. We sketch standard derivations of these effects in the hydrodynamic approximation and then concentrate on possibile unifying approach which is based on consideration of the (anomalously) conserved axial current. The point is that the conservation of chirality is specific for the microscopic, field-theoretic description of massless fermions and their interactions. On the macroscopic side, the standard hydrodynamic equations are not consistent, generally speaking, with conservation of a helical macroscopic motion. Imposing extra constraints on the hydrodynamics might resolve this "clash-of-symmetries" paradox.

  17. Liquid ventilation.

    PubMed

    Sehgal, Arvind; Guaran, Robert

    2005-01-01

    Respiratory diseases are the commonest cause of morbidity and mortality in newborn babies. During the past few years several new modalities of treatment like surfactant have been introduced. One of them, and probably the most fascinating, is of liquid ventilation. Partial liquid ventilation, 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 a 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. It shows further promise for lung lavaging procedures, pulmonary image enhancement, pulmonary administration of drugs and as a technique to increase functional residual capacity in lung hypoplasia syndromes. There are no long-term side effect reported. PMID:16022146

  18. Magnetic circularly polarized X-ray excited optical luminescence (MCP-XEOL)

    NASA Astrophysics Data System (ADS)

    Rogalev, A.; Goulon, J.

    We present recent experimental results of magnetically induced circular polarization of X-ray excited optical luminescence of paramagnetic rare-earth ions. X-ray excitation offers not only the valuable advantage of a high quantum yield but also eliminates the contamination of the luminescence signal with scattered excitation light. These combined advantages allowed us to record MCP-XEOL spectra from a thin layer of powdered samples whereas all previous MCPL experiments were inherently restricted to single crystalline samples or homogeneous liquid solutions.

  19. Liquid electrode

    DOEpatents

    Ekechukwu, Amy A.

    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.

  20. Helium at elevated pressures: Quantum liquid with non-static shear rigidity

    NASA Astrophysics Data System (ADS)

    Bolmatov, D.; Brazhkin, V. V.; Trachenko, K.

    2013-03-01

    The properties of liquid helium have always been a fascinating subject to scientists. The phonon theory of liquids, taking into account liquid non-static shear rigidity, is employed here for studying internal energy and heat capacity of compressed liquid 4He. We demonstrate the good agreement of calculated and experimental heat capacity of liquid helium at elevated pressures and supercritical temperatures. Unexpectedly, helium remains a quantum liquid at elevated pressures for a wide range of temperature supporting both longitudinal and transverse-like phonon excitations. We have found that in the very wide pressure range of 5 MPa-500 MPa, liquid helium near melting temperature is both solid-like and quantum.

  1. Perceptual Load Alters Visual Excitability

    ERIC Educational Resources Information Center

    Carmel, David; Thorne, Jeremy D.; Rees, Geraint; Lavie, Nilli

    2011-01-01

    Increasing perceptual load reduces the processing of visual stimuli outside the focus of attention, but the mechanism underlying these effects remains unclear. Here we tested an account attributing the effects of perceptual load to modulations of visual cortex excitability. In contrast to stimulus competition accounts, which propose that load…

  2. 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).

  3. Lifetime of excited atomic states

    SciTech Connect

    Cresser, J.D.; Tang, A.Z.; Salamo, G.J.; Chan, F.T.

    1986-03-01

    In this paper we derive an expression for the lifetime of excited atomic states taking account of contributions due to nonresonant two-photon transitions. Explicit integration of the two-photon emission spectrum is not required. The results are applied to the case of the hydrogen atom.

  4. 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…

  5. Earthquake-excited crystal-rich magmas

    NASA Astrophysics Data System (ADS)

    Davis, M.; Koenders, C.; Petford, N.

    2005-12-01

    We present the results of a novel set of calculations into the effect of in-situ pressure reduction of a crystal-rich, crustal magma chamber by propagating seismic (P) waves. Three stages in the process are identified. Critically, an instability can arise such that a fluidized, low pressure melt layer develops close to the floor in initially densely packed magma (Φ = 0.6) on near-instantaneous timescales. The role of particle pressure, a newly identified force arising from interactions between adjacent crystals in the magma, is fundamental to the development of the instability, which will not arise in crystal-free liquids. Key variables governing the instability are identified and include the mean particle diameter, the excitation frequency (1-10 Hz), interstitial melt viscosity and melt compressibility. Small penetration depths (high particle pressures) develop most readily in compressible, volatile-bearing magmas at higher frequencies. The quasi-static particle pressure that develops as a result of the spatially-decaying oscillations leads to two effects: 1) a rapid reduction in the interstitial melt pressure (c.0.16 MPa/s) resulting in heterogeneous bubble nucleation, and 2) fluidization of a thin layer at the base of the magma chamber. Both these effects in turn increase the particle pressure. The fluidization effect provides a way of rapidly segregating crystals from interstitial liquid (mechanical differentiation) to produce a potentially unstable melt-rich layer at the chamber floor with a viscosity interval (η) in the range 102 < η <103 Pa s. A non-linear runaway effect is identified, driven by positive feedback between particle pressure, melt viscosity and degassing.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. Liquid air mixing system

    NASA Technical Reports Server (NTRS)

    Martin, Robert B. (Inventor)

    1997-01-01

    A device for mixing liquid nitrogen and liquid oxygen to form liquid air. The mixing device consists of a tube for transferring liquid oxygen positioned within a tube for transferring liquid nitrogen. Supply vessels for liquid oxygen and liquid nitrogen are equally pressurized and connected to the appropriate tubes. Liquid oxygen and nitrogen flow from the supply vessels through the respective tubes and are mixed to form liquid air upon exiting the outlets of the tube. The resulting liquid air is transferred to a holding vessel.

  11. Hydrodynamic pressure in a tank containing two liquids

    SciTech Connect

    Tang, Yu

    1992-05-01

    A study on the dynamic response of a tank containing two different liquids under seismic excitation is presented. Both analytical and numerical (FEM) methods are employed in the analysis. The results obtained by the two methods are in good agreement. The response functions examined include the hydrodynamic pressure, base shear and base moments. A simple approach that can be used to estimate the fundamental natural frequency of the tank-liquid system containing two liquids is proposed. This simple approach is an extension of the method used for estimating the frequency of a tank-liquid system containing only one liquid. This study shows that the dynamic response of a tank filled with two liquids is quite different from that of an identical tank filled with only one liquid.

  12. Hydrodynamic pressure in a tank containing two liquids

    SciTech Connect

    Tang, Yu.

    1992-01-01

    A study on the dynamic response of a tank containing two different liquids under seismic excitation is presented. Both analytical and numerical (FEM) methods are employed in the analysis. The results obtained by the two methods are in good agreement. The response functions examined include the hydrodynamic pressure, base shear and base moments. A simple approach that can be used to estimate the fundamental natural frequency of the tank-liquid system containing two liquids is proposed. This simple approach is an extension of the method used for estimating the frequency of a tank-liquid system containing only one liquid. This study shows that the dynamic response of a tank filled with two liquids is quite different from that of an identical tank filled with only one liquid.

  13. Contactless Inductive Bubble Detection in a Liquid Metal Flow.

    PubMed

    Gundrum, Thomas; Büttner, Philipp; Dekdouk, Bachir; Peyton, Anthony; Wondrak, Thomas; Galindo, Vladimir; Eckert, Sven

    2016-01-01

    The detection of bubbles in liquid metals is important for many technical applications. The opaqueness and the high temperature of liquid metals set high demands on the measurement system. The high electrical conductivity of the liquid metal can be exploited for contactless methods based on electromagnetic induction. We will present a measurement system which consists of one excitation coil and a pickup coil system on the opposite sides of the pipe. With this sensor we were able to detect bubbles in a sodium flow inside a stainless steel pipe and bubbles in a column filled with a liquid Gallium alloy. PMID:26751444

  14. Contactless Inductive Bubble Detection in a Liquid Metal Flow

    PubMed Central

    Gundrum, Thomas; Büttner, Philipp; Dekdouk, Bachir; Peyton, Anthony; Wondrak, Thomas; Galindo, Vladimir; Eckert, Sven

    2016-01-01

    The detection of bubbles in liquid metals is important for many technical applications. The opaqueness and the high temperature of liquid metals set high demands on the measurement system. The high electrical conductivity of the liquid metal can be exploited for contactless methods based on electromagnetic induction. We will present a measurement system which consists of one excitation coil and a pickup coil system on the opposite sides of the pipe. With this sensor we were able to detect bubbles in a sodium flow inside a stainless steel pipe and bubbles in a column filled with a liquid Gallium alloy. PMID:26751444

  15. Collective hypersonic excitations in strongly multiple scattering colloids.

    PubMed

    Still, T; Gantzounis, G; Kiefer, D; Hellmann, G; Sainidou, R; Fytas, G; Stefanou, N

    2011-04-29

    Unprecedented low-dispersion high-frequency acoustic excitations are observed in dense suspensions of elastically hard colloids. The experimental phononic band structure for SiO(2) particles with different sizes and volume fractions is well represented by rigorous full-elastodynamic multiple-scattering calculations. The slow phonons, which do not relate to particle resonances, are localized in the surrounding liquid medium and stem from coherent multiple scattering that becomes strong in the close-packing regime. Such rich phonon-matter interactions in nanostructures, being still unexplored, can open new opportunities in phononics. PMID:21635048

  16. Solitonlike excitations in biological systems

    NASA Astrophysics Data System (ADS)

    Balanovski, Eduardo; Beaconsfield, Peter

    1985-11-01

    A model for solitonlike excitation in DNA is presented and assessed in the context of previous models of collective excitations in other biological systems. A qualitative analysis describes the mechanisms of some DNA function, in particular opening of DNA base pairs to initiate protein synthesis. A formalism is presented which analyzes quantitatively the above-mentioned model, predicts the threshold for B-DNA-->A-DNA transition, and specifies the parameters of particular electromagnetic stimulations that can produce or initiate a variety of DNA responses and effects. The example of insulin production is discussed in detail and theoretical predictions are given for the parameters of an electromagnetic signal reproducing the stimulation to a cell which would lead to insulin production as a response.

  17. Multiphoton-Excited Serotonin Photochemistry

    PubMed Central

    Gostkowski, Michael L.; Allen, Richard; Plenert, Matthew L.; Okerberg, Eric; Gordon, Mary Jane; Shear, Jason B.

    2004-01-01

    We report photochemical and photophysical studies of a multiphoton-excited reaction of serotonin that previously has been shown to generate a photoproduct capable of emitting broadly in the visible spectral region. The current studies demonstrate that absorption of near-infrared light by an intermediate state prepared via three-photon absorption enhances the photoproduct formation yield, with the largest action cross sections (∼10−19 cm2) observed at the short-wavelength limit of the titanium:sapphire excitation source. The intermediate state is shown to persist for at least tens of nanoseconds and likely to be different from a previously reported oxygen-sensitive intermediate. In addition, the two-photon fluorescence action spectrum for the fluorescent photoproduct was determined and found to have a maximum at ∼780 nm (3.2 eV). A general mechanism for this photochemical process is proposed. PMID:15111435

  18. Excitation of Solar Acoustic Modes

    NASA Astrophysics Data System (ADS)

    Pérez, I.; Roca Cortés, T.; GOLF Team

    The excitation of p-modes seems to be produced by turbulence in the convection zone (see, e.g., Kumar, 1997 and the references therein). Low-degree p-mode allowed a study of the energy distribution of the p-mode oscillations, concluding that it is of Boltzmann type (Elsworth et al., 1995; Chaplin et al., 1997). Moreover, these authors suggest that the observed distribution has the property that the high energy events exceed the Boltzmann value, wondering whether this property could have a cause other than stochastic excitation by turbulence. Amongst these, there can be: (a) an artifact due to its very small frequency resolution (? 28 ?Hz ? 10 hours), or (b) some other occasional energy release due to high energy magnetic events. In this work, the energetic distribution of the observed p-mode peaks is studied, having the posibility of using a higher (several) frequency resolution on the basis of the data collected by GOLF, onboard SOHO.

  19. Excitations in Confined Fermi Fluids

    NASA Astrophysics Data System (ADS)

    Hernndez, E. S.

    2002-12-01

    Studies of excitation spectra of Fermi fluids in the presence of various types of spatial symmetry breaking are reviewed. In particular, I discuss the predicted spectra of films of 3He adsorbed on planar substrates and of dilute 40K gases in magnetic traps. Finally, I anticipate some dynamical aspects of 3He gases in onedimensional and quasi-onedimensional adsorbed phases in porous media.

  20. Electron impact excitation of Hg/+/

    NASA Technical Reports Server (NTRS)

    Crandall, D. H.; Phaneuf, R. A.; Dunn, G. H.

    1974-01-01

    A crossed charged beam technique was employed in the investigation reported. The ion beam was crossed at right angles by a magnetically confined electron beam. Cross sections were determined as a function of electron impact energy. Considerable structure in the excitation cross section appears immediately above the threshold. It is pointed out that a primary application of cross sections is related to the calculation of plasma rate coefficients.

  1. Monohydrate catalysis of excited-state double-proton transfer in 7-azaindole

    SciTech Connect

    Pi-Tai Chou; Martinez, M.L.; Cooper, W.C.

    1992-06-25

    In this paper, the green fluorescence of 7-azaindole polyhydrate in liquid water solution is likely not due to tautomerization but due to solvent rearrangement inhibition. 7-azaindole monohydrate also undergoes excited-state double-proton transfer. 17 refs., 3 figs.

  2. Channelopathies of skeletal muscle excitability

    PubMed Central

    Cannon, Stephen C.

    2016-01-01

    Familial disorders of skeletal muscle excitability were initially described early in the last century and are now known to be caused by mutations of voltage-gated ion channels. The clinical manifestations are often striking, with an inability to relax after voluntary contraction (myotonia) or transient attacks of severe weakness (periodic paralysis). An essential feature of these disorders is fluctuation of symptoms that are strongly impacted by environmental triggers such as exercise, temperature, or serum K+ levels. These phenomena have intrigued physiologists for decades, and in the past 25 years the molecular lesions underlying these disorders have been identified and mechanistic studies are providing insights for therapeutic strategies of disease modification. These familial disorders of muscle fiber excitability are “channelopathies” caused by mutations of a chloride channel (ClC-1), sodium channel (NaV1.4), calcium channel (CaV1.1) and several potassium channels (Kir2.1, Kir2.6, Kir3.4). This review provides a synthesis of the mechanistic connections between functional defects of mutant ion channels, their impact on muscle excitability, how these changes cause clinical phenotypes, and approaches toward therapeutics. PMID:25880512

  3. Synaptic Control of Motoneuronal Excitability

    PubMed Central

    Rekling, Jens C.; Funk, Gregory D.; Bayliss, Douglas A.; Dong, Xiao-Wei; Feldman, Jack L.

    2016-01-01

    Movement, the fundamental component of behavior and the principal extrinsic action of the brain, is produced when skeletal muscles contract and relax in response to patterns of action potentials generated by motoneurons. The processes that determine the firing behavior of motoneurons are therefore important in understanding the transformation of neural activity to motor behavior. Here, we review recent studies on the control of motoneuronal excitability, focusing on synaptic and cellular properties. We first present a background description of motoneurons: their development, anatomical organization, and membrane properties, both passive and active. We then describe the general anatomical organization of synaptic input to motoneurons, followed by a description of the major transmitter systems that affect motoneuronal excitability, including ligands, receptor distribution, pre- and postsynaptic actions, signal transduction, and functional role. Glutamate is the main excitatory, and GABA and glycine are the main inhibitory transmitters acting through ionotropic receptors. These amino acids signal the principal motor commands from peripheral, spinal, and supraspinal structures. Amines, such as serotonin and norepinephrine, and neuropeptides, as well as the glutamate and GABA acting at metabotropic receptors, modulate motoneuronal excitability through pre- and postsynaptic actions. Acting principally via second messenger systems, their actions converge on common effectors, e.g., leak K+ current, cationic inward current, hyperpolarization-activated inward current, Ca2+ channels, or presynaptic release processes. Together, these numerous inputs mediate and modify incoming motor commands, ultimately generating the coordinated firing patterns that underlie muscle contractions during motor behavior. PMID:10747207

  4. Entanglement entropy of electronic excitations.

    PubMed

    Plasser, Felix

    2016-05-21

    A new perspective into correlation effects in electronically excited states is provided through quantum information theory. The entanglement between the electron and hole quasiparticles is examined, and it is shown that the related entanglement entropy can be computed from the eigenvalue spectrum of the well-known natural transition orbital (NTO) decomposition. Non-vanishing entanglement is obtained whenever more than one NTO pair is involved, i.e., in the case of a multiconfigurational or collective excitation. An important implication is that in the case of entanglement it is not possible to gain a complete description of the state character from the orbitals alone, but more specific analysis methods are required to decode the mutual information between the electron and hole. Moreover, the newly introduced number of entangled states is an important property by itself giving information about excitonic structure. The utility of the formalism is illustrated in the cases of the excited states of two interacting ethylene molecules, the conjugated polymer para-phenylene vinylene, and the naphthalene molecule. PMID:27208936

  5. Magnetic excitations in thulium metal

    SciTech Connect

    Fernandez-Baca, J.A.; Nicklow, R.M.; Rhyne, J.J.; National Inst. of Standards and Technology , Gaithersburg, MD )

    1989-01-01

    We have performed inelastic neutron scattering measurements on a single crystal specimen of Tm at wavevectors {rvec {kappa}} = (1,1, {zeta}) and (0,0,2 + {zeta}) ({zeta} = 0, {hor ellipsis}, 1). Most of the measurements have been made at T = 5K, where Tm exhibits a seven layer ferrimagnetic-antiphase-domain structure (four moments up, parallel to the c-axis, followed by three moments down). At this temperature the excitation spectra consist of three peaks. The two lower energy excitations have been identified as originating from magneto-vibrational scattering from the TA phonon, while the higher energy excitation is magnetic and exhibits only a weak dispersion (between 8.3 and 9.6 meV). At T = 50K, a temperature at which the system exhibits a c-axis sinusoidally modulated structure, the magnetic mode shows significant softening and broadening. The magneto-vibrational scattering vanishes above the Neel temperature (T{sub N} = 58.5K) while the magnetic mode persists at least up to T = 70K. These results suggest that the Hamiltonian in this system is dominated by the crystal-field-anistropy energy, and that the exchange interaction is relatively weak. 9 refs., 2 figs.

  6. Electronic excitations in Guanine quadruplexes.

    PubMed

    Changenet-Barret, Pascale; Hua, Ying; Markovitsi, Dimitra

    2015-01-01

    Guanine rich DNA strands, such as those encountered at the extremities of human chromosomes, have the ability to form four-stranded structures (G-quadruplexes) whose building blocks are guanine tetrads. G-quadruplex structures are intensively studied in respect of their biological role, as targets for anticancer therapy and, more recently, of their potential applications in the field of molecular electronics. Here we focus on their electronic excited states which are compared to those of non-interacting mono-nucleotides and those of single and double stranded structures. Particular emphasis is given to excited state relaxation processes studied by time-resolved fluorescence spectroscopy from femtosecond to nanosecond time scales. They include ultrafast energy transfer and trapping of ππ* excitations by charge transfer states. The effect of various structural parameters, such as the nature of the metal cations located in the central cavity of G-quadruplexes, the number of tetrads or the conformation of the constitutive single strands, are examined. PMID:24563011

  7. Wedding ring shaped excitation coil

    DOEpatents

    MacLennan, Donald A.; Tsai, Peter

    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. 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

  9. 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

  10. 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.

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

    SciTech Connect

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

    2015-08-15

    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.

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

    DOEpatents

    Freund, Samuel M.; Maier, II, William B.; Beattie, Willard H.; Holland, Redus F.

    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.

  13. 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.

  14. 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)

  15. Rocking response of tanks containing two liquids

    SciTech Connect

    Tang, Y.

    1995-01-01

    A study on the dynamic response of upright circular cylindrical liquid-storage tanks containing two different liquids under a rocking base motion with an arbitrary temporal variation is presented. Only rigid tanks were studied. The response quantities examined include the hydrodynamic pressure, sloshing wave height and the associated frequencies, base shear and moments. Each of these response quantities is expressed as the sum of the so-called impulsive component and convective component. Unlike the case of tanks containing one liquid, in which the response is controlled by one parameter, height-to-radius ratio, the response of tanks containing two different liquids are controlled by three parameters: height-to-radius ratio, and mass density ratio and height ratio of the two liquids. The interrelationship of the responses of the tank-liquid system to rocking and lateral base excitations is established by examining numerical results extensively. The study shows that some of the response quantities for tank-liquid system under a rocking base motion can be determined from the available data for the response of an identical tank under a horizontal base motion. Base rocking motion can occur in a ground-supported tank or in an elevated tank under earthquake motions.

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

    DOEpatents

    Comaskey, Brian J.; Ault, Earl R.; Kuklo, Thomas C.

    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.

  17. 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.

  18. Turbulent swirling jets with excitation

    NASA Technical Reports Server (NTRS)

    Taghavi, Rahmat; Farokhi, Saeed

    1988-01-01

    An existing cold-jet facility at NASA Lewis Research Center was modified to produce swirling flows with controllable initial tangential velocity distribution. Two extreme swirl profiles, i.e., one with solid-body rotation and the other predominated by a free-vortex distribution, were produced at identical swirl number of 0.48. Mean centerline velocity decay characteristics of the solid-body rotation jet flow exhibited classical decay features of a swirling jet with S - 0.48 reported in the literature. However, the predominantly free-vortex distribution case was on the verge of vortex breakdown, a phenomenon associated with the rotating flows of significantly higher swirl numbers, i.e., S sub crit greater than or equal to 0.06. This remarkable result leads to the conclusion that the integrated swirl effect, reflected in the swirl number, is inadequate in describing the mean swirling jet behavior in the near field. The relative size (i.e., diameter) of the vortex core emerging from the nozzle and the corresponding tangential velocity distribution are also controlling factors. Excitability of swirling jets is also investigated by exciting a flow with a swirl number of 0.35 by plane acoustic waves at a constant sound pressure level and at various frequencies. It is observed that the cold swirling jet is excitable by plane waves, and that the instability waves grow about 50 percent less in peak r.m.s. amplitude and saturate further upstream compared to corresponding waves in a jet without swirl having the same axial mass flux. The preferred Strouhal number based on the mass-averaged axial velocity and nozzle exit diameter for both swirling and nonswirling flows is 0.4.

  19. 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)

  20. 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)

  1. 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.

  2. 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.

  3. Unsteady pressure response of a liquid in a cylindrical container subject to vertical vibration

    NASA Astrophysics Data System (ADS)

    Sudo, Seiichi; Hashimoto, Hiroyuki

    1988-05-01

    Experimental results on the pressure response, surface wave motion, and container wall response of liquid in a cylindrical container subject to high-frequency vertical oscillations are presented. The amplitude of pressure was found to increase exponentially with time when the excitation acceleration exceeded a threshold value. The pressure amplitude maximum decreased with increasing excitation acceleration. The present results can be explained by the wave velocity of the liquid-bubble-shell system approaching the resonant velocity as the void fraction increases.

  4. 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.

  5. Theoretical studies of electronically excited states

    NASA Astrophysics Data System (ADS)

    Besley, Nicholas A.

    2014-10-01

    Time-dependent density functional theory is the most widely used quantum chemical method for studying molecules in electronically excited states. However, excited states can also be computed within Kohn-Sham density functional theory by exploitingmethods that converge the self-consistent field equations to give excited state solutions. The usefulness of single reference self-consistent field based approaches for studying excited states is demonstrated by considering the calculation of several types of spectroscopy including the infrared spectroscopy of molecules in an electronically excited state, the rovibrational spectrum of the NO-Ar complex, core electron binding energies and the emission spectroscopy of BODIPY in water.

  6. Excitation of surface electromagnetic waves on water.

    PubMed

    Singh, A K; Goben, C A; Davarpanah, M; Boone, J L

    1978-11-01

    Excitation of surface electromagnetic waves (SEW) on water was studied using optical coupling techniques at microwave frequencies. Excitation of SEW was also achieved using direct horn antenna coupling. The transmitted SEW power was increased by adding acid and salt to water. The horn antenna gave the maximum excitation efficiency 70%. It was increased to 75% by collimating the electromagnetic beam in the vertical direction. Excitation efficiency for the prism (0 degrees pitch angle) and grating couplers were 15.2% and 10.5% respectively. By changing the prism coupler pitch angle to +36 degrees , its excitation efficiency was increased to 82%. PMID:20204001

  7. The vacuum ultraviolet spectrum of krypton and xenon excimers excited in a cooled dc discharge

    NASA Astrophysics Data System (ADS)

    Gerasimov, G.; Krylov, B.; Loginov, A.; Zvereva, G.; Hallin, R.; Arnesen, A.; Heijkenskjöld, F.

    1998-01-01

    We present results of an experimental and theoretical study of the VUV spectra of krypton and xenon excimers excited by a dc discharge in a capillary tube cooled by liquid nitrogen. The studied spectral regions of 115-170 nm and 140-195 nm for krypton and xenon respectively correspond to transitions between the lowest excited dimer states 1u, 0u+ and the weakly bound ground state 0g+. A semiempirical method was suggested and applied to describe the experimental spectra and to estimate the temperature of the radiating plasma volume. Electron impact, transferring dimers from the ground state to the excited states, is shown to be an efficient excitation mechanism in the 100-850 hPa and the 10-50 mA pressure and discharge current ranges. The spectra obtained as well as the results of calculations corroborate the high rate of this mechanism.

  8. Control of liquid crystal molecular orientation using ultrasound vibration

    NASA Astrophysics Data System (ADS)

    Taniguchi, Satoki; Koyama, Daisuke; Shimizu, Yuki; Emoto, Akira; Nakamura, Kentaro; Matsukawa, Mami

    2016-03-01

    We propose a technique to control the orientation of nematic liquid crystals using ultrasound and investigate the optical characteristics of the oriented samples. An ultrasonic liquid crystal cell with a thickness of 5-25 μm and two ultrasonic lead zirconate titanate transducers was fabricated. By exciting the ultrasonic transducers, the flexural vibration modes were generated on the cell. An acoustic radiation force to the liquid crystal layer was generated, changing the molecular orientation and thus the light transmission. By modulating the ultrasonic driving frequency and voltage, the spatial distribution of the molecular orientation of the liquid crystals could be controlled. The distribution of the transmitted light intensity depends on the thickness of the liquid crystal layer because the acoustic field in the liquid crystal layer is changed by the orientational film.

  9. Solvent effects on non-resonant vibrational deactivation: N 2( ν = 1) deactivated by CH 4 in liquid Ar/liquid N 2 mixtures

    NASA Astrophysics Data System (ADS)

    Turnidge, M. L.; Simpson, C. J. S. M.

    1996-10-01

    New measurements have been made of rate constants for the vibrational deactivation of N 2( ν = 1) by CH 4 in liquid Ar/liquid N 2 mixtures. The ratio of the liquid phase rate constants, kL,M for the liquid mixture over kL,Ar for liquid argon solution, varies non-linearly with composition. The results imply a saturation effect which occurs when one solvent N 2 molecule is present in the first solvation shell of the excited molecule. It is proposed that this is due to the formation of a N 2( ν = 1) … N 2 collision complex.

  10. Multiphoton excitation of fluorescent DNA base analogs.

    PubMed

    Katilius, Evaldas; Woodbury, Neal W

    2006-01-01

    Multiphoton excitation was used to investigate properties of the fluorescent DNA base analogs, 2-aminopurine (2AP) and 6-methylisoxanthopterin (6MI). 2-aminopurine, a fluorescent analog of adenine, was excited by three-photon absorption. Fluorescence correlation measurements were attempted to evaluate the feasibility of using three-photon excitation of 2AP for DNA-protein interaction studies. However, high excitation power and long integration times needed to acquire high signal-to-noise fluorescence correlation curves render three-photon excitation FCS of 2AP not very useful for studying DNA base dynamics. The fluorescence properties of 6-methylisoxanthopterin, a guanine analog, were investigated using two-photon excitation. The two-photon absorption cross-section of 6MI was estimated to be about 2.5 x 10(-50) cm(4)s (2.5 GM units) at 700 nm. The two-photon excitation spectrum was measured in the spectral region from 700 to 780 nm; in this region the shape of the two-photon excitation spectrum is very similar to the shape of single-photon excitation spectrum in the near-UV spectral region. Two-photon excitation of 6MI is suitable for fluorescence correlation measurements. Such measurements can be used to study DNA base dynamics and DNA-protein interactions over a broad range of time scales. PMID:16965161

  11. Multiphoton excitation of fluorescent DNA base analogs

    NASA Astrophysics Data System (ADS)

    Katilius, Evaldas; Woodbury, Neal W.

    2006-07-01

    Multiphoton excitation was used to investigate properties of the fluorescent DNA base analogs, 2-aminopurine (2AP) and 6-methylisoxanthopterin (6MI). 2-aminopurine, a fluorescent analog of adenine, was excited by three-photon absorption. Fluorescence correlation measurements were attempted to evaluate the feasibility of using three-photon excitation of 2AP for DNA-protein interaction studies. However, high excitation power and long integration times needed to acquire high signal-to-noise fluorescence correlation curves render three-photon excitation FCS of 2AP not very useful for studying DNA base dynamics. The fluorescence properties of 6-methylisoxanthopterin, a guanine analog, were investigated using two-photon excitation. The two-photon absorption cross-section of 6MI was estimated to be about 2.510-50 cm4s (2.5 GM units) at 700 nm. The two-photon excitation spectrum was measured in the spectral region from 700 to 780 nm; in this region the shape of the two-photon excitation spectrum is very similar to the shape of single-photon excitation spectrum in the near-UV spectral region. Two-photon excitation of 6MI is suitable for fluorescence correlation measurements. Such measurements can be used to study DNA base dynamics and DNA-protein interactions over a broad range of time scales.

  12. Microwave Excitation In ECRIS plasmas

    SciTech Connect

    Ciavola, G.; Celona, L.; Consoli, F.; Gammino, S.; Maimone, F.; Barbarino, S.; Catalano, R. S.; Mascali, D.; Tumino, L.

    2007-09-28

    A number of phenomena related to the electron cyclotron resonance ion sources (ECRIS) has been better understood recently by means of the improvement of comprehension of the coupling mechanism between microwave generators and ECR plasma. In particular, the two frequency heating and the frequency tuning effect, that permit a remarkable increase of the current for the highest charge states ions, can be explained in terms of modes excitation in the cylindrical cavity of the plasma chamber. Calculations based on this theoretical approach have been performed, and the major results will be presented. It will be shown that the electric field pattern completely changes for a few MHz frequency variations and the changes in ECRIS performances can be correlated to the efficiency of the power transfer between electromagnetic field and plasma.

  13. 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.

  14. 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.

  15. Excitation of interstellar hydrogen chloride

    NASA Astrophysics Data System (ADS)

    Neufeld, David A.; Green, Sheldon

    1994-09-01

    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 abundance2/3, 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 10-9, a value which amounts to only approximately 0.3% of the cosmic abundance of chlorine nuclei. Given a fractional abundance of 2 x 10-9, the contribution of HCl emission to the total radiative cooling of a dense clump is small. For Orion, we predict a flux approximately 10-19 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.

  16. Vibrationally Excited C4H

    NASA Astrophysics Data System (ADS)

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

    2015-02-01

    Rotational spectra in four new excited vibrational levels of the linear carbon chain radical C4H 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 {{X}2}{{{Σ }}+} ground vibrational state of C4H and were assigned to new bending vibrational levels, two each with 2{Σ } and 2{\\Pi } vibrational symmetry. The new levels are tentatively assigned to the 1{{ν }6} and 1{{ν }5} bending vibrational modes (both with 2{\\Pi } symmetry), and the 1{{ν }6}+1{{ν }7} and 1{{ν }5}+1{{ν }6} combination levels (2{Σ } symmetry) on the basis of the derived spectroscopic constants, relative intensities in our discharge source, and published laser spectroscopic and quantum calculations. Prior spectroscopic constants in the 1{{ν }7} and 2{{ν }7} levels were refined. Also presented are interferometric maps of the ground state and the 1{{ν }7} level obtained with the Submillimeter Array (SMA) near 257 GHz which show that C4H is present near the central star in IRC+10216. We found no evidence with the SMA for the new vibrationally excited levels of C4H at a peak flux density averaged over a 3\\prime\\prime synthesized beam of ≥slant 0.15 Jy/beam in the 294-296 and 304-306 GHz range, but it is anticipated that rotational lines in the new levels might be observed in IRC+10216 when ALMA attains its full design capability.

  17. Excited states in Pd99

    NASA Astrophysics Data System (ADS)

    Sihotra, S.; Naik, Z.; Kumar, S.; Singh, K.; Goswamy, J.; Singh, N.; Kumar, R.; Singh, R. P.; Muralithar, S.; Bhowmik, R. K.; Palit, R.; Mehta, D.

    2011-02-01

    Excited states in the Pd99 nucleus populated in the As75(Si28, p3n) fusion-evaporation reaction at Elab=120 MeV have been investigated through in-beam γ-ray spectroscopic techniques using an array of Compton-suppressed clover detectors. The level scheme is established up to excitation energy ~11.5 MeV and spin ~25ℏ with the addition of about 60 new transitions. The level structures observed in Pd99 have been interpreted in the framework of a microscopic theory based on the deformed Hartree-Fock and angular momentum projection techniques. Band structures at lower spins are based on the low-Ω νg7/2 and νd5/2 orbitals, and those at higher spins are reproduced for the π(g9/2)5⊗π(g7/2)⊗ν(g7/2)2⊗ν(h11/2)2⊗ν(g9/2)-1 and π(g9/2)6⊗ν(g9/2)10⊗ν(g7/2)2⊗ν(h11/2) configurations. The octupole correlations in Pd99 have been inferred from new interband E1 transitions linking the ΔI=1 states of the bands based on the νh11/2 and νd5/2 orbitals (Δl=3, Δj=3, and Δπ=-1) with the deduced B(E1) values ~10-6 W.u.

  18. 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.

  19. Excitement in shame: the price we pay.

    PubMed

    Aledort, Stewart L

    2014-01-01

    This paper explores the role of excitement in shame, extending the theoretical underpinnings of my work (Aledort, 2002, 2003, 2008, 2009) on narcissism and the omnipotent child syndrome. Shame, excitement, and early narcissistic self-states are complexly intermingled, each influencing the other. Empathy alone is insufficient; the passion connected to shame can be easily hidden. Detailed case studies describe a model for working with the excitement in shame, how it functions, and how it gets resolved. PMID:24320576

  20. Design evaluation: S-band exciters

    NASA Technical Reports Server (NTRS)

    1974-01-01

    A design evaluation study was conducted to produce S-band exciter (SBE) system to provide a highly stable phase or modulated carrier for transmission to spacecraft. The exciter is part of an S-band receiver/exciter/ranging system at Spaceflight Tracking and Data Network (STDN) ground stations. The major features of the system are defined. Circuit diagrams of the electronic components are provided.

  1. Longitudinal and transverse modes of slosh wave excitation in rotating dewar associated with gravity jitters

    NASA Technical Reports Server (NTRS)

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

    1991-01-01

    Characteristics of slosh waves based on the dynamical behavior of oscillations at the liquid-vapor interface have been investigated. Twelve case studies of slosh wave excitation due to various frequencies of gravity jitters under different rotating speeds of the propellant tank and different levels of background gravity environment have been simulated. The study shows that slosh waves excited inside the spacecraft propellant tank are characterized by the lowest frequency of the waves initiated, frequencies of the gravity jitters imposed on the propellant system, the levels of background gravity environment, and dewar rotating speeds. Conditions for suppression and amplification of the slosh waves are discussed.

  2. Excited-state density functional theory

    NASA Astrophysics Data System (ADS)

    Harbola, Manoj K.; Hemanadhan, M.; Shamim, Md; Samal, P.

    2012-11-01

    Starting with a brief introduction to excited-state density functional theory, we present our method of constructing modified local density approximated (MLDA) energy functionals for the excited states. We show that these functionals give accurate results for kinetic energy and exchange energy compared to the ground state LDA functionals. Further, with the inclusion of GGA correction, highly accurate total energies for excited states are obtained. We conclude with a brief discussion on the further direction of research that include the construction of correlation energy functional and exchange potential for excited states.

  3. Excited states and photodissociation of hydroxymethyl hydroperoxide.

    PubMed

    Eisfeld, Wolfgang; Francisco, Joseph S

    2008-05-01

    The structure of hydroxymethyl hydroperoxide (HOCH(2)OOH) (HMHP) has been examined using coupled cluster and multireference configuration interaction methods to study the excited states and probable photodissociation products. The results are compared to experiments. The vertical excitation energies for several excited states of HOCH(2)OOH are presented as well as the excited state energies along the O-O, O-H, C-O, and C-H dissociation pathways. The results help in the interpretation of experimental UV absorption spectra and elucidate the photodissociation mechanism of HMHP under tropospheric conditions. PMID:18465919

  4. Single determinant calculations of excited state polarizabilities

    NASA Astrophysics Data System (ADS)

    Jonsson, Dan; Norman, Patrick; Ågren, Hans

    1997-12-01

    We apply response theory to simulate excited state polarizabilities emphasizing the possibility to do so by means of optimization of a ground state single determinant only. The excited state polarizabilities are given by the double residues of the cubic response functions. A set of molecules with varying ground state configurations and properties have been considered: water, ozone, formaldehyde, ethylene, butadiene, cyclobutadiene, pyridine, pyrazine and s-tetrazine. The results have been compared to excited state experiments where available and with linear response calculations of the multi-determinant optimized excited state. It is shown that calculations of excited state polarizabilities based on a ground state optimized single determinant work well for most of the cases investigated. This contention is exemplified by the fact the gas phase value from an electrochromism experiment for the polarizability of the 1 1B2 excited state of formaldehyde is better reproduced by ground state cubic response theory than by the corresponding separate state linear response function calculation, and by that the calculations call for an experimental reinvestigation of the excited state polarizabilities of s-tetrazine. A few prerequisites are given: The excited state should be isolated in energy, the ordering of the main contributing states should be reproduced, and the geometric conformation of the excited state in question should not be very different from the ground state geometry. The computational and formal advantages of the approach are discussed.

  5. Sloshing response in a tank containing two liquids

    NASA Astrophysics Data System (ADS)

    Tang, Y.; Ma, D. C.; Chang, Y. W.

    A study on the sloshing response in a tank containing two different liquids under seismic excitation is presented. Both analytical and numerical (FEM) methods are employed in the analysis. The results obtained by the two methods are in good agreement. The response quantities examined include the sloshing wave height, the natural frequencies of the sloshing motion, and the vertical displacement at the interface of the two liquids. It is shown that the maximum sloshing wave height may increase significantly, and the fundamental period of the sloshing motion is longer than that in an identical tank containing only one liquid.

  6. Sloshing response in a tank containing two liquids

    SciTech Connect

    Tang, Y.; Ma, D.C.; Chang, Y.W.

    1991-01-01

    A study on the sloshing response in a tank containing two different liquids under seismic excitation is presented. Both analytical and numerical (FEM) methods are employed in the analysis. The results obtained by the two methods are in good agreement. The response quantities examined include the sloshing wave height, the natural frequencies of the sloshing motion, and the vertical displacement at the interface of the two liquids. It is shown that the maximum sloshing wave height may increase significantly, and the fundamental period of the sloshing motion is longer than that in an identical tank containing only one liquid. 10 refs., 12 figs.

  7. Liquid crystal fibers of bent-core molecules

    NASA Astrophysics Data System (ADS)

    Jákli, Antal; Krüerke, Daniel; Nair, Geetha G.

    2003-05-01

    Although the liquid-crystal research is well established in science, there are newly emerging exciting systems, that deserve extensive basic studies. One of these areas is the research of the bent-shaped molecules (so-called “banana liquid crystals”), which have delicate chirality and polarity properties. In this paper we show that these materials also have very unusual rheological features, such as the formation of stable fluid fibers and bridges. Under electric fields, these objects present striking mechanical effects, such as horizontal and transversal vibrations. Studies indicate that the research of banana-liquid-crystal fibers may lead to new type of artificial muscle systems.

  8. A unification of Z2 spin liquids on Kagome lattice

    NASA Astrophysics Data System (ADS)

    Cho, Gil Young; Lu, Yuan-Ming; Vishwanath, Ashvin

    2014-03-01

    While there is mounting numerical evidence for the existence of a gapped Z2 spin liquid in the Kagome Heisenberg model, a complete characterization of this topological phase remains to be accomplished. A defining property, the projective symmetry group (PSG) which fixes how the emergent excitations of the spin liquid phase transform under symmetry, remains to be determined. Two popular mean field approaches, based on a fermionic or bosonic representation of spinons, provide seemingly disparate classifications. Here we discuss a duality relation that pairs a fermionic spinon ansatz to a bosonic one, which unifies these classifications, and provides concrete predictions for identifying the spin liquid state on the Kagome lattice.

  9. Transverse optic-like modes in binary liquids

    NASA Astrophysics Data System (ADS)

    Bryk, Taras; Mryglod, Ihor

    1999-10-01

    Generalized collective mode approach and MD simulations are applied for the study of transverse dynamics in a LJ fluid KrAr and a liquid alloy Mg 70Zn 30. The optic-like excitations, caused by the mass-concentration fluctuations, are found in both mixtures considered. Mode contributions into the total spectral function are investigated.

  10. Micro-dynamics in 2D Dusty Plasma Liquids

    NASA Astrophysics Data System (ADS)

    Lai, Ying-Ju; Teng, Lee-Wen; Tu, Pie-San; Chu, Hong-Yu; I, Lin

    2002-12-01

    We review the recent studies on the micro-dynamics in strongly coupled dust Coulomb liquids suspended in low pressure glow discharges. Under the interplay of stochastic thermal noise and Coulomb interaction, cooperative fast hopping strings and vortices excited from the small amplitude caged motion in the ordered lattice domains are the key cooperative excitations in the system. Their spatio-temporal statistical behaviors obey the similar generic power law scaling as sac type avalanche in coupled sub-excitable system under noise. The hopping can be further enhanced by the external stress and suppressed by the finite boundary. The liquid exhibits nonlinear viscoelastic response under high frequency AC shear drives and exhibits layering transition in a narrow gap down to a few molecular width. Travelling soliton-type micro-bubble can be formed through intense pulsed laser ablation.

  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. Multi-photon excitation microscopy

    PubMed Central

    Diaspro, Alberto; Bianchini, Paolo; Vicidomini, Giuseppe; Faretta, Mario; Ramoino, Paola; Usai, Cesare

    2006-01-01

    Multi-photon excitation (MPE) microscopy plays a growing role among microscopical techniques utilized for studying biological matter. In conjunction with confocal microscopy it can be considered the imaging workhorse of life science laboratories. Its roots can be found in a fundamental work written by Maria Goeppert Mayer more than 70 years ago. Nowadays, 2PE and MPE microscopes are expected to increase their impact in areas such biotechnology, neurobiology, embryology, tissue engineering, materials science where imaging can be coupled to the possibility of using the microscopes in an active way, too. As well, 2PE implementations in noninvasive optical bioscopy or laser-based treatments point out to the relevance in clinical applications. Here we report about some basic aspects related to the phenomenon, implications in three-dimensional imaging microscopy, practical aspects related to design and realization of MPE microscopes, and we only give a list of potential applications and variations on the theme in order to offer a starting point for advancing new applications and developments. PMID:16756664

  13. Excited delirium: A psychiatric review.

    PubMed

    Lipsedge, Maurice

    2016-04-01

    The term 'excited delirium' (ED) is used to explain sudden and unexpected restraint-related deaths. Since the 1990s, ED has often been identified as the principal cause of death in restrained individuals, rather than the restraint procedure itself. Forensic pathologists and psychiatrists attach different meanings to the term delirium. For psychiatrists, delirium is a specific technical term, which implies a grave and potentially life-threatening underlying physical illness. If a patient dies during a bout of delirium, psychiatrists assume that there will be autopsy evidence to demonstrate the primary underlying organic cause. Conversely, pathologists appear to be using the term ED to refer to restraint-related deaths in either highly disturbed cocaine users or psychiatric patients in a state of extreme agitation. In these cases, there is no underlying physical disorder other than a terminal cardiac arrhythmia. As the term ED has different meanings for psychiatrists and for pathologists, it would be helpful for these two professional groups to develop a mutually agreed terminology. PMID:26055153

  14. Quantitative assessment of radiation force effect at the dielectric air-liquid interface

    PubMed Central

    Capeloto, Otávio Augusto; Zanuto, Vitor Santaella; Malacarne, Luis Carlos; Baesso, Mauro Luciano; Lukasievicz, Gustavo Vinicius Bassi; Bialkowski, Stephen Edward; Astrath, Nelson Guilherme Castelli

    2016-01-01

    We induce nanometer-scale surface deformation by exploiting momentum conservation of the interaction between laser light and dielectric liquids. The effect of radiation force at the air-liquid interface is quantitatively assessed for fluids with different density, viscosity and surface tension. The imparted pressure on the liquids by continuous or pulsed laser light excitation is fully described by the Helmholtz electromagnetic force density. PMID:26856622

  15. Quantitative assessment of radiation force effect at the dielectric air-liquid interface

    NASA Astrophysics Data System (ADS)

    Capeloto, Otávio Augusto; Zanuto, Vitor Santaella; Malacarne, Luis Carlos; Baesso, Mauro Luciano; Lukasievicz, Gustavo Vinicius Bassi; Bialkowski, Stephen Edward; Astrath, Nelson Guilherme Castelli

    2016-02-01

    We induce nanometer-scale surface deformation by exploiting momentum conservation of the interaction between laser light and dielectric liquids. The effect of radiation force at the air-liquid interface is quantitatively assessed for fluids with different density, viscosity and surface tension. The imparted pressure on the liquids by continuous or pulsed laser light excitation is fully described by the Helmholtz electromagnetic force density.

  16. Quantitative assessment of radiation force effect at the dielectric air-liquid interface.

    PubMed

    Capeloto, Otávio Augusto; Zanuto, Vitor Santaella; Malacarne, Luis Carlos; Baesso, Mauro Luciano; Lukasievicz, Gustavo Vinicius Bassi; Bialkowski, Stephen Edward; Astrath, Nelson Guilherme Castelli

    2016-01-01

    We induce nanometer-scale surface deformation by exploiting momentum conservation of the interaction between laser light and dielectric liquids. The effect of radiation force at the air-liquid interface is quantitatively assessed for fluids with different density, viscosity and surface tension. The imparted pressure on the liquids by continuous or pulsed laser light excitation is fully described by the Helmholtz electromagnetic force density. PMID:26856622

  17. 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.

  18. Liquid level detector

    DOEpatents

    Grasso, Albert P.

    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.

  19. 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.

  20. 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

  1. 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.

  2. 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…

  3. Higgs type excitations in cold atom systems

    NASA Astrophysics Data System (ADS)

    Huang, FeiJie; Chen, QiHui; Liu, WuMing

    2013-12-01

    Higgs type excitations are the excitations which give mass to particles. The Higgs type excitations has a critical role both in particle physics and condensed matter physics. In particle physics, the suspected Higgs boson has been found by the Large Hadron Collider (LHC) in 2012. In condensed matter physics, the Higgs type excitations relate to order phase of the system. In this review, we present an overview of recent studies on the Higgs type excitations both in non-interacting and interacting cold atom systems. First, in non-interacting cold atom system, by synthesizing artificial non-Abelian gauge potential, we demonstrate that when a non-Abelian gauge potential is reduced to Abelian potential, the Abelian part constructs spin-orbit coupling, and the non-Abelian part emerges Higgs excitations. Secondly, the Higgs excitations which are the reputed Higgs amplitude mode in interacting cold atom system are discussed. We review the theoretical model and the experimental detection of Higgs amplitude mode in two dimensional superfluid. The observation of both Higgs type excitations in real experiments are also discussed.

  4. Excitation energy migration dynamics in upconversion nanomaterials.

    PubMed

    Tu, Langping; Liu, Xiaomin; Wu, Fei; Zhang, Hong

    2015-03-21

    Recent efforts and progress in unraveling the fundamental mechanism of excitation energy migration dynamics in upconversion nanomaterials are covered in this review, including short- and long-term interactions and other interactions in homogeneous and heterogeneous nanostructures. Comprehension of the role of spatial confinement in excitation energy migration processes is updated. Problems and challenges are also addressed. PMID:25223635

  5. Peak structural response to nonstationary random excitations

    NASA Technical Reports Server (NTRS)

    Shinozuka, M.; Yang, J.-N.

    1971-01-01

    Study establishes distribution function of peak response values, based on frequency interpretation. Excitations considered include impact loading on landing gears and aircraft gust loading. Because of relative severity of excitations, prediction of fatigue and maximum response characteristics is important part of task of structural analysis and design.

  6. Excitation-scanning hyperspectral imaging microscope

    PubMed Central

    Favreau, Peter F.; Hernandez, Clarissa; Heaster, Tiffany; Alvarez, Diego F.; Rich, Thomas C.; Prabhat, Prashant; Leavesley, Silas J.

    2014-01-01

    Abstract. Hyperspectral imaging is a versatile tool that has recently been applied to a variety of biomedical applications, notably live-cell and whole-tissue signaling. Traditional hyperspectral imaging approaches filter the fluorescence emission over a broad wavelength range while exciting at a single band. However, these emission-scanning approaches have shown reduced sensitivity due to light attenuation from spectral filtering. Consequently, emission scanning has limited applicability for time-sensitive studies and photosensitive applications. In this work, we have developed an excitation-scanning hyperspectral imaging microscope that overcomes these limitations by providing high transmission with short acquisition times. This is achieved by filtering the fluorescence excitation rather than the emission. We tested the efficacy of the excitation-scanning microscope in a side-by-side comparison with emission scanning for detection of green fluorescent protein (GFP)-expressing endothelial cells in highly autofluorescent lung tissue. Excitation scanning provided higher signal-to-noise characteristics, as well as shorter acquisition times (300  ms/wavelength band with excitation scanning versus 3  s/wavelength band with emission scanning). Excitation scanning also provided higher delineation of nuclear and cell borders, and increased identification of GFP regions in highly autofluorescent tissue. These results demonstrate excitation scanning has utility in a wide range of time-dependent and photosensitive applications. PMID:24727909

  7. Excitation-scanning hyperspectral imaging microscope.

    PubMed

    Favreau, Peter F; Hernandez, Clarissa; Heaster, Tiffany; Alvarez, Diego F; Rich, Thomas C; Prabhat, Prashant; Leavesley, Silas J

    2014-04-01

    Hyperspectral imaging is a versatile tool that has recently been applied to a variety of biomedical applications, notably live-cell and whole-tissue signaling. Traditional hyperspectral imaging approaches filter the fluorescence emission over a broad wavelength range while exciting at a single band. However, these emission-scanning approaches have shown reduced sensitivity due to light attenuation from spectral filtering. Consequently, emission scanning has limited applicability for time-sensitive studies and photosensitive applications. In this work, we have developed an excitation-scanning hyperspectral imaging microscope that overcomes these limitations by providing high transmission with short acquisition times. This is achieved by filtering the fluorescence excitation rather than the emission. We tested the efficacy of the excitation-scanning microscope in a side-by-side comparison with emission scanning for detection of green fluorescent protein (GFP)-expressing endothelial cells in highly autofluorescent lung tissue. Excitation scanning provided higher signal-to-noise characteristics, as well as shorter acquisition times (300  ms/wavelength band with excitation scanning versus 3  s/wavelength band with emission scanning). Excitation scanning also provided higher delineation of nuclear and cell borders, and increased identification of GFP regions in highly autofluorescent tissue. These results demonstrate excitation scanning has utility in a wide range of time-dependent and photosensitive applications. PMID:24727909

  8. 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.

  9. Ensemble density functional theory method correctly describes bond dissociation, excited state electron transfer, and double excitations

    SciTech Connect

    Filatov, Michael; Huix-Rotllant, Miquel; Burghardt, Irene

    2015-05-14

    State-averaged (SA) variants of the spin-restricted ensemble-referenced Kohn-Sham (REKS) method, SA-REKS and state-interaction (SI)-SA-REKS, implement ensemble density functional theory for variationally obtaining excitation energies of molecular systems. In this work, the currently existing version of the SA-REKS method, which included only one excited state into the ensemble averaging, is extended by adding more excited states to the averaged energy functional. A general strategy for extension of the REKS-type methods to larger ensembles of ground and excited states is outlined and implemented in extended versions of the SA-REKS and SI-SA-REKS methods. The newly developed methods are tested in the calculation of several excited states of ground-state multi-reference systems, such as dissociating hydrogen molecule, and excited states of donor–acceptor molecular systems. For hydrogen molecule, the new method correctly reproduces the distance dependence of the lowest excited state energies and describes an avoided crossing between the doubly excited and singly excited states. For bithiophene–perylenediimide stacked complex, the SI-SA-REKS method correctly describes crossing between the locally excited state and the charge transfer excited state and yields vertical excitation energies in good agreement with the ab initio wavefunction methods.

  10. Ensemble density functional theory method correctly describes bond dissociation, excited state electron transfer, and double excitations

    NASA Astrophysics Data System (ADS)

    Filatov, Michael; Huix-Rotllant, Miquel; Burghardt, Irene

    2015-05-01

    State-averaged (SA) variants of the spin-restricted ensemble-referenced Kohn-Sham (REKS) method, SA-REKS and state-interaction (SI)-SA-REKS, implement ensemble density functional theory for variationally obtaining excitation energies of molecular systems. In this work, the currently existing version of the SA-REKS method, which included only one excited state into the ensemble averaging, is extended by adding more excited states to the averaged energy functional. A general strategy for extension of the REKS-type methods to larger ensembles of ground and excited states is outlined and implemented in extended versions of the SA-REKS and SI-SA-REKS methods. The newly developed methods are tested in the calculation of several excited states of ground-state multi-reference systems, such as dissociating hydrogen molecule, and excited states of donor-acceptor molecular systems. For hydrogen molecule, the new method correctly reproduces the distance dependence of the lowest excited state energies and describes an avoided crossing between the doubly excited and singly excited states. For bithiophene-perylenediimide stacked complex, the SI-SA-REKS method correctly describes crossing between the locally excited state and the charge transfer excited state and yields vertical excitation energies in good agreement with the ab initio wavefunction methods.

  11. Ensemble density functional theory method correctly describes bond dissociation, excited state electron transfer, and double excitations.

    PubMed

    Filatov, Michael; Huix-Rotllant, Miquel; Burghardt, Irene

    2015-05-14

    State-averaged (SA) variants of the spin-restricted ensemble-referenced Kohn-Sham (REKS) method, SA-REKS and state-interaction (SI)-SA-REKS, implement ensemble density functional theory for variationally obtaining excitation energies of molecular systems. In this work, the currently existing version of the SA-REKS method, which included only one excited state into the ensemble averaging, is extended by adding more excited states to the averaged energy functional. A general strategy for extension of the REKS-type methods to larger ensembles of ground and excited states is outlined and implemented in extended versions of the SA-REKS and SI-SA-REKS methods. The newly developed methods are tested in the calculation of several excited states of ground-state multi-reference systems, such as dissociating hydrogen molecule, and excited states of donor-acceptor molecular systems. For hydrogen molecule, the new method correctly reproduces the distance dependence of the lowest excited state energies and describes an avoided crossing between the doubly excited and singly excited states. For bithiophene-perylenediimide stacked complex, the SI-SA-REKS method correctly describes crossing between the locally excited state and the charge transfer excited state and yields vertical excitation energies in good agreement with the ab initio wavefunction methods. PMID:25978880

  12. Drop formation mechanism in a vertically vibrated liquid column

    NASA Astrophysics Data System (ADS)

    Hashimoto, H.; Sudo, S.

    1987-05-01

    The purpose of the present paper is to clarify the hydrodynamical mechanism of surface disintegration and drop formation over a wide range of input frequency and amplitude. The experiment involved longitudinal excitation of a container of water on an electrodynamic shaker. The free surface behavior in the vibrating container was analyzed by using a 16-mm high-speed camera and an automatic liquid surface detector. The threshold of surface disintegration and the wave characteristics of large-amplitude surface motions with liquid drops in a vertically excited rectangular container have been investigated experimentally. The drop formation mechanism and the drop size distribution have also been examined, both theoretically and experimentally. The results obtained here should provide useful clues for future research and development of application fields of the liquid sloshing phenomena.

  13. Effects of core turbulence on jet excitability

    NASA Technical Reports Server (NTRS)

    Mankbadi, Reda R.; Raman, Ganesh; Rice, Edward J.

    1989-01-01

    The effects of varying freestream core turbulence on the evolution of a circular jet with and without tonal excitation are examined. Measurements are made on an 8.8 cm diameter jet at a Mach number of 0.3. The jet is excitated by plane waves at Strouhal number 0.5. For the excited and unexcited cases the turbulence level is varied by screens and grids placed upstream of the nozzle exit. The experiment results are compared with a theoretical model which incorporates a variable core turbulence and considers the energy interactions between the mean flow, the turbulence and the forced component. Both data and theory indicate that increasing the freestream turbulence diminishes the excitability of the jet and reduces the effect of excitation on the spreading rate of the jet.

  14. Effects of core turbulence on jet excitability

    NASA Technical Reports Server (NTRS)

    Mankbadi, Reda R.; Rice, Edward J.; Raman, Ganesh

    1989-01-01

    The effects of varying freestream core turbulence on the evolution of a circular jet with and without tonal excitation are examined. Measurements are made on an 8.8 cm diameter jet at a Mach number of 0.3. The jet is excited by plane waves at Strouhal number 0.5. For the excited and unexcited cases the turbulence level is varied by screens and grids placed upstream of the nozzle exit. The experiment results are compared with a theoretical model which incorporates a variable core turbulence and considers the energy interactions between the mean flow, the turbulence and the forced component. Both data and theory indicate that increasing the freestream turbulence diminishes the excitability of the jet and reduces the effect of excitation on the spreading rate of the jet.

  15. Gravity jitter induced slosh waves in liquid propellant and disturbances of fluid stresses on spacecraft

    NASA Technical Reports Server (NTRS)

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

    1992-01-01

    The paper investigates 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. Fluid stress distribution caused by the excitation of slosh waves and their associated large amplitude disturbances on the liquid-vapor interface and exerted on the outer and inner walls of a rotating dewar container are also examined. It is shown that fluid stress distributions near the outer and inner walls of the rotating dewar are closely related to the characteristics of slosh waves excited in the liquid-vapor interface in the rotating dewar tank. This can be of utility in managing spacecraft dynamic control leading to control of spacecraft imbalance caused by the uneven fluid stress distribution due to slosh wave excitations at the interface between liquid and vapor propellants.

  16. 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 ππ* 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 π(2) electronic ground state (S0) and Baird's rule in the lowest ππ* 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-π-conjugated and cross-hyperconjugated compound classes. PMID:25043523

  17. 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.

  18. Terahertz Spectroscopy of Excited Water

    NASA Astrophysics Data System (ADS)

    Yu, Shanshan; Pearson, John C.; Drouin, Brian J.; Walters, Adam; Müller, Holger S. P.; Brünken, Sandra

    2010-06-01

    The observation and characterization of water spectra have been intensely pursued in the astrophysical community. Its rotational transitions in the ground, (010) (v_2 = 1), (020), (100), and (001) states are primary targets of the ongoing Herschel mission. In this study, laboratory terahertz spectroscopy of water was carried out at JPL and Cologne, with the goals to measure all transitions HIFI might see and critically review and fit the lowest 5 vibrational states. DC discharge, radio frequency discharge and heating tapes were used to generate highly excited water. A total of 145 pure rotational transitions in the (000), (010), (020), (100), and (001) states of water were observed in the 293-1969 GHz region. Of these, 86 have been detected for the first time with MW accuracy. So far, the 1(1,0)-1(0,1) transition was observed for all five states; the 2(1,2)-1(0,1) transition was observed for (000), (100), and (001) but is missing for (010) (1753914 GHz) and (020) (1872972 GHz); the 1(1,1)-0(0,0) transition was observed for all states but (020) (1332967 GHz). The analysis is still in progress, and we will present the most recent fitting results to date. There are difficulties in fitting water spectra, such as the strong centrifugal distortion, which gives a non-convergent Watson Hamiltonian. In addition, the first triad states (100, 020, and 001) are strongly coupled. The latest attempt at a global fit of these 5 states using Euler series achieved a reduced RMS of 8.4 (Pickett et al. 2005, J. Mol. Spectrosc. 233, 174).

  19. Excitation gap of fractal quantum hall states in graphene.

    PubMed

    Luo, Wenchen; Chakraborty, Tapash

    2016-01-13

    In the presence of a magnetic field and an external periodic potential the Landau level spectrum of a two-dimensional electron gas exhibits a fractal pattern in the energy spectrum which is described as the Hofstadter's butterfly. In this work, we develop a Hartree-Fock theory to deal with the electron-electron interaction in the Hofstadter's butterfly state in a finite-size graphene with periodic boundary conditions, where we include both spin and valley degrees of freedom. We then treat the butterfly state as an electron crystal so that we could obtain the order parameters of the crystal in the momentum space and also in an infinite sample. A phase transition between the liquid phase and the fractal crystal phase can be observed. The excitation gaps obtained in the infinite sample is comparable to those in the finite-size study, and agree with a recent experimental observation. PMID:26657089

  20. Excitation gap of fractal quantum hall states in graphene

    NASA Astrophysics Data System (ADS)

    Luo, Wenchen; Chakraborty, Tapash

    2016-01-01

    In the presence of a magnetic field and an external periodic potential the Landau level spectrum of a two-dimensional electron gas exhibits a fractal pattern in the energy spectrum which is described as the Hofstadter’s butterfly. In this work, we develop a Hartree-Fock theory to deal with the electron-electron interaction in the Hofstadter’s butterfly state in a finite-size graphene with periodic boundary conditions, where we include both spin and valley degrees of freedom. We then treat the butterfly state as an electron crystal so that we could obtain the order parameters of the crystal in the momentum space and also in an infinite sample. A phase transition between the liquid phase and the fractal crystal phase can be observed. The excitation gaps obtained in the infinite sample is comparable to those in the finite-size study, and agree with a recent experimental observation.

  1. Thermal excitations of warped membranes

    NASA Astrophysics Data System (ADS)

    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 {hα(q)}, α =D+1,...,d, in Fourier space with zero mean and a power-law variance hα(q1)hβ(q2)¯˜δα ,βδq1,-q2q1-dh. The case D =2, d =3, with dh=4 could be realized by flash-polymerizing lyotropic smectic liquid crystals. For D 4-ηf(F) (dh<4-ηf(F)), where ηf(F) is the scaling exponent for tethered surfaces with a flat background metric, and the scaling exponents are related through ηu+ηf=dh-D (ηu+2ηf=4-D).

  2. Liquid seeding atomizer

    NASA Technical Reports Server (NTRS)

    Seegmiller, Henry L. B. (Inventor)

    1987-01-01

    An atomizer for a liquid having an air supply is described. Liquid supply tubes extend longitudinally along the air supply tube. The air supply tube has at least one air orifice extending from an inner surface of the tube through the tube. The liquid supply tubes are positioned on either side of the air orifices and the liquid tubes are sealed to the air supply tube. The liquid supply tubes with facing liquid orifices are positioned adjacent to each of the air orifices. The liquid supply tubes are laterally spaced apart at the liquid orifices at a distance less than the diameter of the air orifices to enable a beneficial venturi effect when the atomizer is in operation.

  3. Liquid seeding atomizer

    NASA Astrophysics Data System (ADS)

    Seegmiller, Henry L. B.

    1987-03-01

    An atomizer for a liquid having an air supply is described. Liquid supply tubes extend longitudinally along the air supply tube. The air supply tube has at least one air orifice extending from an inner surface of the tube through the tube. The liquid supply tubes are positioned on either side of the air orifices and the liquid tubes are sealed to the air supply tube. The liquid supply tubes with facing liquid orifices are positioned adjacent to each of the air orifices. The liquid supply tubes are laterally spaced apart at the liquid orifices at a distance less than the diameter of the air orifices to enable a beneficial venturi effect when the atomizer is in operation.

  4. Precision liquid level sensor

    DOEpatents

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

    A precision liquid level sensor utilizes a balanced 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.

  5. Zero gravity liquid mixer

    NASA Technical Reports Server (NTRS)

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

    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.

  6. Vortex Excitation in Superfluid {sup 4}He: A Diffusion Monte Carlo Study

    SciTech Connect

    Giorgini, S.; Boronat, J.; Casulleras, J.

    1996-09-01

    We present a diffusion Monte Carlo study of a single vortex in two-dimensional superfluid liquid {sup 4}He within the fixed-node approximation. We use both the Feynman phase and an improved phase which includes backflow correlations to model the nodal surface of the vortex wave function. Results for the particle density, core radius, and excitation energies are presented. {copyright} {ital 1996 The American Physical Society.}

  7. Instantaneous Liquid Interfaces

    PubMed Central

    Willard, Adam P.; Chandler, David

    2010-01-01

    We describe and illustrate a simple procedure for identifying a liquid interface from atomic coordinates. In particular, a coarse grained density field is constructed, and the interface is defined as a constant density surface for this coarse grained field. In applications to a molecular dynamics simulation of liquid water, it is shown that this procedure provides instructive and useful pictures of liquid-vapor interfaces and of liquid-protein interfaces. PMID:20055377

  8. Liquid level sensing device

    DOEpatents

    Tokarz, Richard D.

    1983-01-01

    A liquid level sensing device comprising a load cell supporting a column or stack of segments freely resting on one another. The density of each element is substantially identical to that of the surrounding liquid. The elements are freely guided within a surrounding tube. As each element is exposed above the liquid level, its weight will be impressed through the column to the load cell, thereby providing a signal at the load cell directly proportional to the liquid level elevation.

  9. 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.

  10. Dynamic and high-resolution live cell imaging by direct electron beam excitation.

    PubMed

    Nawa, Yasunori; Inami, Wataru; Chiba, Akito; Ono, Atsushi; Miyakawa, Atsuo; Kawata, Yoshimasa; Lin, Sheng; Terakawa, Susumu

    2012-02-27

    We propose a direct electron-beam excitation assisted optical microscope with a resolution of a few tens of nanometers and it can be applied for observation of dynamic movements of nanoparticles in liquid. The technique is also useful for live cell imaging under physiological conditions as well as observation of colloidal solution, microcrystal growth in solutions, etc. In the microscope, fluorescent materials are directly excited with a focused electron beam. The direct excitation with an electron beam yields high spatial resolution since the electron beam can be focused to a few tens of nanometers in the specimens. In order to demonstrate the potential of our proposed microscope, we observed the movements of fluorescent nanoparticles, which can be used for labelling specimens, in a water-based solution. We also demonstrated an observation result of living CHO cells. PMID:22418370

  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. Liquid metal cold trap

    DOEpatents

    Hundal, Rolv

    1976-01-01

    A cold trap assembly for removing impurities from a liquid metal being provided with a hole between the incoming impure liquid metal and purified outgoing liquid metal which acts as a continuous bleed means and thus prevents the accumulation of cover gases within the cold trap assembly.

  13. 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.

  14. Supergluing MOF liquid marbles.

    PubMed

    Chin, Jia Min; Reithofer, Michael R; Tan, Tristan Tsai Yuan; Menon, Ajay Govinda; Chen, Eric Yu; Chow, Chin Ann; Hor, Andy Tzi Sum; Xu, Jianwei

    2013-01-18

    Growth of NH(2)-MIL-53(Al) on alumina microparticles followed by post-synthetic modification with perfluorooctyl or caproic groups produces highly hydrophobic microparticles which are utilized for the formation of liquid marbles. Interfacial polymerization of ethyl-2-cyanoacrylate on the surface of the liquid marbles produces stable liquid capsules. PMID:23202539

  15. 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.

  16. Zero-order suppression for two-photon holographic excitation.

    PubMed

    Hernandez, Oscar; Guillon, Marc; Papagiakoumou, Eirini; Emiliani, Valentina

    2014-10-15

    Wavefront shaping with liquid-crystal spatial light modulators (LC-SLMs) is frequently hindered by a remaining fraction of undiffracted light, the so-called "zero-order." This contribution is all the more detrimental in configurations for which the LC-SLM is Fourier conjugated to a sample by a lens, because in these cases this undiffracted light produces a diffraction-limited spot at the image focal plane. In this Letter we propose to minimize two-photon (2P) excitation of the sample, resulting from this unmodulated light, by introducing optical aberrations to the excitation beam. Aberrations are subsequently compensated by the LC-SLM, but only for the modulated part of the beam, and not for the zero-order component. In order to experimentally demonstrate the method, we use astigmatism as the optical aberration, by simply adding one or two cylindrical lenses in the optical path of the beam. A 10⁴ decrease in zero-order-induced 2P fluorescence intensity is demonstrated. Combining this approach with temporal focusing is shown to decrease zero-order fluorescence by a factor of 4·10⁶. PMID:25361128

  17. Interfacial Phenomena of Magnetic Fluid with Permanent Magnet in a Longitudinally Excited Container

    NASA Astrophysics Data System (ADS)

    Sudo, Seiichi; Wakuda, Hirofumi; Yano, Tetsuya

    2008-02-01

    This paper describes the magnetic fluid sloshing in a longitudinally excited container. Liquid responses of magnetic fluid with a permanent magnet in a circular cylindrical container subject to vertical vibration are investigated. Experiments are performed on a vibration- testing system which provided longitudinal excitation. A cylindrical container made with the acrylic plastic is used in the experiment. A permanent magnet is in the state of floating in a magnetic fluid. The disk-shaped and ring-shaped magnets are examined. The different interfacial phenomena from the usual longitudinal liquid sloshing are observed. It is found that the wave motion frequency of magnetic fluid with a disk-shaped magnet in the container subject to vertical vibration is exactly same that of the excitation. In the case of ring-shaped magnet, the first symmetrical mode of one-half subharmonic response is dominant at lower excitation frequencies. The magnetic fluid disintegration of the free surface was also observed by a high-speed video camera system.

  18. Interfacial Phenomena of Magnetic Fluid with Permanent Magnet in a Longitudinally Excited Container

    SciTech Connect

    Sudo, Seiichi; Wakuda, Hirofumi; Yano, Tetsuya

    2008-02-21

    This paper describes the magnetic fluid sloshing in a longitudinally excited container. Liquid responses of magnetic fluid with a permanent magnet in a circular cylindrical container subject to vertical vibration are investigated. Experiments are performed on a vibration- testing system which provided longitudinal excitation. A cylindrical container made with the acrylic plastic is used in the experiment. A permanent magnet is in the state of floating in a magnetic fluid. The disk-shaped and ring-shaped magnets are examined. The different interfacial phenomena from the usual longitudinal liquid sloshing are observed. It is found that the wave motion frequency of magnetic fluid with a disk-shaped magnet in the container subject to vertical vibration is exactly same that of the excitation. In the case of ring-shaped magnet, the first symmetrical mode of one-half subharmonic response is dominant at lower excitation frequencies. The magnetic fluid disintegration of the free surface was also observed by a high-speed video camera system.

  19. 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.

  20. Electron-impact excitation of holmium atoms

    SciTech Connect

    Smirnov, Yu M

    2000-06-30

    The electron-impact excitation of holmium atoms was studied by the method of extended crossing beams. The cross sections and the optical excitation functions were obtained for odd levels of Ho I, including the 22014 cm{sup -1} laser level. Over 99% of the atoms were shown to reside in the ground level prior to collisions with electrons. Also measured were the excitation cross sections for six even levels, which presumably participate in the formation of inversion population in a gas-discharge holmium vapour laser. (laser applications and other topics in quantum electronics)

  1. Spatiotemporal dynamics of networks of excitable nodes

    NASA Astrophysics Data System (ADS)

    Steele, Aaron J.; Tinsley, Mark; Showalter, Kenneth

    2006-03-01

    A network of excitable nodes based on the photosensitive Belousov-Zhabotinsky reaction is studied in experiments and simulations. The addressable medium allows both local and nonlocal links between the nodes. The initial spread of excitation across the network as well as the asymptotic oscillatory behavior are described. Synchronization of the spatiotemporal dynamics occurs by entrainment to high-frequency network pacemakers formed by excitation loops. Analysis of the asymptotic behavior reveals that the dynamics of the network is governed by a subnetwork selected during the initial transient period.

  2. 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.

  3. Vibrational excitation of CO by blackbody radiation

    NASA Technical Reports Server (NTRS)

    Arriola, L.; Wilson, J. W.

    1985-01-01

    Lasers excited by blackbody radiation are of interest for power beaming applications in space. In such a system sunlight is collected and focused into a blackbody cavity, heating it to approximately 2000 K. An appropriate absorbing molecule is vibrationally heated but not translationally heated when passed through the blackbody cavity. The vibrationally excited gas is then mixed with a lasant resulting in laser emission. The number density of CO molecules within a blackbody radiation field of a given temperature and pressure is calculated. Such calculations show the degree of excitation achievable, under ideal conditions, from blackbody pumping.

  4. Relativistic dynamical spin excitations of magnetic adatoms

    NASA Astrophysics Data System (ADS)

    dos Santos Dias, M.; Schweflinghaus, B.; Blügel, S.; Lounis, S.

    2015-02-01

    We present a first-principles theory of dynamical spin excitations in the presence of spin-orbit coupling. The broken global spin rotational invariance leads to a new sum rule. We explore the competition between the magnetic anisotropy energy and the external magnetic field, as well as the role of electron-hole excitations, through calculations for 3 d -metal adatoms on the Cu(111) surface. The spin excitation resonance energy and lifetime display nontrivial behavior, establishing the strong impact of relativistic effects. We legitimate the use of the Landau-Lifshitz-Gilbert equation down to the atomic limit, but with parameters that differ from a stationary theory.

  5. Electron-impact excitation of interstellar molecules

    NASA Astrophysics Data System (ADS)

    Faure, A.; Tennyson, J.; Varambhia, H. N.; Kokoouline, V.; Greene, C. H.; Stoecklin, T.

    2007-07-01

    Electron-impact excitation of molecules plays a crucial role in astrophysical environments where the electron fraction is higher than about 10-5, e.g. in the diffuse interstelar medium, in shocks and comets. We present here recent ab initio calculations of rate coefficients for the rotational excitation of HCN and HCO^+ by thermal electrons. Our calculations are based on the molecular R-matrix method combined with the Adiabatic-Nuclei-Rotation (ANR) approximation corrected for threshold effects. Our major results are i) the prediction of collisional propensity rules less rigorous than previously assumed and ii) the prediction of significant excitation differences between ionic and neutral molecules.

  6. Propagation of a liquid-liquid explosion

    SciTech Connect

    Harlow, F.H.; Ruppel, H.M.

    1981-08-01

    Direct contact between two liquids, one cold and the other hot, may be precluded by the presence of a vapor film. Bridging of this film by one or both fluids results in rapid local boiling, which may initiate a propagating liquid-liquid explosion. A mechanism is discussed for the propagation that involves implosion of the film, rapid mixing of the fluids, heat exchange to warm the cold fluid above the temperature for spontaneous nucleation, and the explosive generation of vapor, which in turn continues to sustain the film implosion. Plausibility for the model is demonstrated by means of numerical studies by high-speed computer.

  7. PREFACE: 6th Liquid Matter Conference

    NASA Astrophysics Data System (ADS)

    Dijkstra, Marjolein; van Roij, René; Vroege, Gert Jan; Lekkerkerker, Henk; Frenkel, Daan

    2005-11-01

    This special issue of Journal of Physics: Condensed Matter contains the Proceedings of the 6th Liquid Matter Conference held in Utrecht, The Netherlands, 2-6 July 2005. The three-yearly Liquid Matter Conference is organized by the Liquids Section of the Condensed Matter Division of the European Physical Society. This series of meetings began in Lyon in 1990. The most recent meeting was held in 2003 in Konstanz. The aim of the Liquid Matter Conferences is to bring together scientists working on the liquid state of matter. This rapidly growing field includes the physics, chemistry, biology and chemical engineering of liquid matter as well as various applied research areas. In fact, the Utrecht meeting had, for the first time, a special session devoted to Fundamental Challenges in Applied Liquid Physics and Microfluidics. The Utrecht meeting had 760 registered participants from four continents. An important event at this meeting was the award of the First Liquid Matter Prize of the European Physical Society to Professor Jean-Pierre Hansen FRS, of Cambridge University. In addition to a plenary speech by the recipient of the Liquid Matter Prize, the scientific programme consisted of 10 plenary lectures, 117 symposia talks, 25 of which were keynote lectures and some 650 poster contributions. The meeting also hosted a one-day symposium of the Division of Liquids and Interfaces of the Chemical Sciences division of NWO. This special issue of Journal of Physics: Condensed Matter contains 61 of the oral communications. Liquid state physics is at the interface of many fields of research. As a consequence, many of the attendants come from adjacent fields and find in the Liquid Matter Conference a forum to meet experts from other areas of research. This aspect of the Liquid Matter Conference makes it an exciting meeting as it not only offers the participants an up-to-date picture of the status of research into the liquid state of matter, but it also allows them to establish new (and often unexpected) trans-disciplinary contacts for joint scientific endeavours. This applies in particular to the area of soft condensed matter such as colloidal suspensions, polymeric systems and biological materials. The conference was held at the Uithof, the campus of the University of Utrecht. The organizers gratefully acknowledge the generosity of the University and City of Utrecht, which enabled us to stage both the scientific part of the conference and several festive and cultural events in some of the most attractive venues of the Netherlands. We were also delighted by the substantial contributions offered by the sponsors of the 6th Liquid Matter Conference. With this support it became possible to support a large number of scientists who would otherwise not have been able to attend. Finally, we owe a great debt of gratitude to the secretarial staff of the conference and the many students, postdocs and other colleagues who helped tirelessly (and very efficiently) to make the conference run smoothly. The Board of the Liquids Section of the European Physical Society decided that the 7th Liquid Matter Conference will be held in Lund (Sweden). The tentative dates are Friday 27 June 2008 to Tuesday 1 July 2008.

  8. Radiation monitor for liquids

    DOEpatents

    Koster, James E.; Bolton, Richard D.

    1999-01-01

    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.

  9. 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.

  10. Resonant intermolecular transfer of vibrational energy in liquid water

    NASA Astrophysics Data System (ADS)

    Woutersen, Sander; Bakker, Huib J.

    1999-12-01

    Many biological, chemical and physical processes involve the transfer of energy. In the case of electronic excitations, transfer between molecules is rapid, whereas for vibrations in the condensed phase, resonant energy transfer is an unlikely process because the typical timescale of vibrational relaxation (a few picoseconds) is much shorter than that of resonant intermolecular vibrational energy transfer. For the OH-stretch vibration in liquid water, which is of particular importance due to its coupling to the hydrogen bond, extensive investigations have shown that vibrational relaxation takes place with a time constant of 740 +/- 25 femtoseconds (ref. 7). So for resonant intermolecular energy transfer to occur in liquid water, the interaction between the OH-stretch modes of different water molecules needs to be extremely strong. Here we report time-resolved pump-probe laser spectroscopy measurements that reveal the occurrence of fast resonant intermolecular transfer of OH-stretch excitations over many water molecules before the excitation energy is dissipated. We find that the transfer process is mediated by dipole-dipole interactions (the Förster transfer mechanism) and additional mechanisms that are possibly based on intermolecular anharmonic interactions involving hydrogen bonds. Our findings suggest that liquid water may play an important role in transporting vibrational energy between OH groups located on either different biomolecules or along extended biological structures. OH groups in a hydrophobic environment should accordingly be able to remain in a vibrationally excited state longer than OH groups in a hydrophilic environment.

  11. 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.

  12. Acidic Ionic Liquids.

    PubMed

    Amarasekara, Ananda S

    2016-05-25

    Ionic liquid with acidic properties is an important branch in the wide ionic liquid field and the aim of this article is to cover all aspects of these acidic ionic liquids, especially focusing on the developments in the last four years. The structural diversity and synthesis of acidic ionic liquids are discussed in the introduction sections of this review. In addition, an unambiguous classification system for various types of acidic ionic liquids is presented in the introduction. The physical properties including acidity, thermo-physical properties, ionic conductivity, spectroscopy, and computational studies on acidic ionic liquids are covered in the next sections. The final section provides a comprehensive review on applications of acidic ionic liquids in a wide array of fields including catalysis, CO2 fixation, ionogel, electrolyte, fuel-cell, membrane, biomass processing, biodiesel synthesis, desulfurization of gasoline/diesel, metal processing, and metal electrodeposition. PMID:27175515

  13. 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 μA. 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.

  14. Effective local potentials for excited states

    NASA Astrophysics Data System (ADS)

    Staroverov, Viktor N.; Glushkov, Vitaly N.

    2010-12-01

    The constrained variational Hartree-Fock method for excited states of the same symmetry as the ground state [Chem. Phys. Lett. 287, 189 (1998)] is combined with the effective local potential (ELP) method [J. Chem. Phys. 125, 081104 (2006)] to generate Kohn-Sham-type exact-exchange potentials for singly excited states of many-electron systems. Illustrative examples include the three lowest 2S states of the Li and Na atoms and the three lowest 3S states of He and Be. For the systems studied, excited-state ELPs differ from the corresponding ground-state potentials in two respects: They are less negative and have small additional "bumps" in the outer electron region. The technique is general and can be used to approximate excited-state exchange-correlation potentials for other orbital-dependent functionals.

  15. 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

  16. Low Power PZT Exciter for Thermosonics

    NASA Astrophysics Data System (ADS)

    Kang, B.; Cawley, P.

    2007-03-01

    An ultrasonic horn originally designed for welding has generally been used for thermosonic testing. However, it is difficult to obtain reproducible and controllable excitation with the existing horn system because of nonlinearity in the coupling; surface damage can also be produced by hammering caused by loss of contact between the tip of the horn and the structure. Therefore, this research was conducted to develop a simple excitation system that should excite sufficient strain for the detection of the defects of interest at all relevant positions in the structure, and should also be easy to attach to and remove from the structure. It must also avoid surface damage. Test results suggest that a simple, small wax coupled PZT exciter may provide a convenient, reliable thermosonic test system in applications where relatively low strain levels are required for damage detection.

  17. Broadband single-molecule excitation spectroscopy

    PubMed Central

    Piatkowski, Lukasz; Gellings, Esther; van Hulst, Niek F.

    2016-01-01

    Over the past 25 years, single-molecule spectroscopy has developed into a widely used tool in multiple disciplines of science. The diversity of routinely recorded emission spectra does underpin the strength of the single-molecule approach in resolving the heterogeneity and dynamics, otherwise hidden in the ensemble. In early cryogenic studies single molecules were identified by their distinct excitation spectra, yet measuring excitation spectra at room temperature remains challenging. Here we present a broadband Fourier approach that allows rapid recording of excitation spectra of individual molecules under ambient conditions and that is robust against blinking and bleaching. Applying the method we show that the excitation spectra of individual molecules exhibit an extreme distribution of solvatochromic shifts and distinct spectral shapes. Importantly, we demonstrate that the sensitivity and speed of the broadband technique is comparable to that of emission spectroscopy putting both techniques side-by-side in single-molecule spectroscopy. PMID:26794035

  18. Nuclear excitation by electronic transition (NEET).

    SciTech Connect

    Ahmad, I.; Dunford, R. W.; Esbensen, H.; Gemmell, D. S.; Kanter, E. P.; Kraessig, B.; Ruett, U.; Southworth, S. H.

    1999-04-28

    We present a report on recent measurements using the Advanced Photon Source at Argonne National Laboratory to explore the phenomenon of Nuclear Excitation by Electronic Transition (NEET) in the {sup 189}Os atomic/nuclear system.

  19. 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.

  20. Synchronization of pulse-coupled excitable neurons

    NASA Astrophysics Data System (ADS)

    Masuda, Naoki; Aihara, Kazuyuki

    2001-11-01

    Collective behavior of pulse-coupled oscillatory neurons has been investigated widely. In many cases, however, real neurons are intrinsically not oscillatory but excitable. The networks of excitable neurons can have their own characteristic dynamics, and they are of interest also from the viewpoint of functional assemblies. In the present paper, the collective behavior of pulse-coupled excitable neurons has been investigated using phase description. It is shown that full synchronization is achieved in networks of excitable leaky integrate-and-fire neurons and discrete-time Nagumo-Sato neurons. The cooperative roles of external spike inputs, decay of internal states, and feedback spikes are explained. Enhancement of synchronization by refractoriness and noise is also reported.

  1. Broadband single-molecule excitation spectroscopy

    NASA Astrophysics Data System (ADS)

    Piatkowski, Lukasz; Gellings, Esther; van Hulst, Niek F.

    2016-01-01

    Over the past 25 years, single-molecule spectroscopy has developed into a widely used tool in multiple disciplines of science. The diversity of routinely recorded emission spectra does underpin the strength of the single-molecule approach in resolving the heterogeneity and dynamics, otherwise hidden in the ensemble. In early cryogenic studies single molecules were identified by their distinct excitation spectra, yet measuring excitation spectra at room temperature remains challenging. Here we present a broadband Fourier approach that allows rapid recording of excitation spectra of individual molecules under ambient conditions and that is robust against blinking and bleaching. Applying the method we show that the excitation spectra of individual molecules exhibit an extreme distribution of solvatochromic shifts and distinct spectral shapes. Importantly, we demonstrate that the sensitivity and speed of the broadband technique is comparable to that of emission spectroscopy putting both techniques side-by-side in single-molecule spectroscopy.

  2. 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.

  3. Inclination Excitation in Extrasolar Planetary Systems

    NASA Astrophysics Data System (ADS)

    Becker, Juliette; Adams, Fred C.

    2015-01-01

    The Kepler Mission has detected dozens of planetary systems with more than four transiting planets. This sample provides a collection of planetary systems with little or no excited inclination between the inferred orbits. This present study examines the magnitude and efficacy of three potential mechanisms for exciting orbital inclination in these systems: self-excitation of orbital inclination in initially coplanar planetary systems, perturbations by larger bodies within the planetary systems, and perturbations by massive bodies external to the systems. For each of these mechanisms, we determine the regime(s) of parameter space for which orbital inclination excitation is effective. This work provides constraints on the properties (masses and orbital elements) of possible additional bodies in observed planetery systems, and on their dynamical history. One interesting application is to consider the relative size of the external perturbations both in and out of clusters.

  4. Excited state g factors in Te125

    NASA Astrophysics Data System (ADS)

    Chamoli, S. K.; Stuchbery, A. E.; East, M. C.

    2009-11-01

    The transient-field technique has been used to measure, with considerably improved precision, the g factors of the 3/2+ and 5/2+ states in Te125 at 444 and 463 keV, respectively, relative to the g factor of the first excited state in Te126. Together with shell model and weak-coupling core-excitation model calculations, the g-factor measurements provide insight into the orbital occupation of the odd neutron for the low-excitation states in Te125. A new 9/2+ level at 1029 keV, together with a firm 7/2+ spin assignment for the level at 1018 keV, identifies candidate states for the coupling of the s1/2 neutron to the 4+ core excitation.

  5. 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

  6. Detecting cracked rotors using auxiliary harmonic excitation

    NASA Astrophysics Data System (ADS)

    Sawicki, Jerzy T.; Friswell, Michael I.; Kulesza, Zbigniew; Wroblewski, Adam; Lekki, John D.

    2011-03-01

    Cracked rotors are not only important from a practical and economic viewpoint, they also exhibit interesting dynamics. This paper investigates the modelling and analysis of machines with breathing cracks, which open and close due to the self-weight of the rotor, producing a parametric excitation. After reviewing the modelling of cracked rotors, the paper analyses the use of auxiliary excitation of the shaft, often implemented using active magnetic bearings to detect cracks. Applying a sinusoidal excitation generates response frequencies that are combinations of the rotor spin speed and excitation frequency. Previously this system was analysed using multiple scales analysis; this paper suggests an alternative approach based on the harmonic balance method, and validates this approach using simulated and experimental results. Consideration is also given to some issues to enable this approach to become a robust condition monitoring technique for cracked shafts.

  7. 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.

  8. The aeronomy of vibrationally excited ozone

    NASA Technical Reports Server (NTRS)

    Frederick, J. E.; Allen, J. E., Jr.

    1980-01-01

    Theoretical calculations show that above 80 km in the earth's atmosphere the production of vibrationally excited ozone by chemical processes leads to number densities which are usually larger than those expected for local thermodynamic equilibrium. Quenching of highly excited molecules produced in O+O2+M, O3+M provided a significant source of the lower lying states above the mesopause while the 9.6 microns emission of O3 (0,0,1) was a major sink. Analysis of available laboratory results implied that reactions involving excited ozone play a significant role in the global ozone balance despite the relatively small abundance of the molecule. However, this effect is implicit in many of the rate coefficients currently used in stratospheric calculations. In the upper mesosphere and lower thermosphere, where the excited state populations differ from those for thermal equilibrium, published reaction rate data are not necessarily applicable to aeronomic calculations.

  9. Broadband single-molecule excitation spectroscopy.

    PubMed

    Piatkowski, Lukasz; Gellings, Esther; van Hulst, Niek F

    2016-01-01

    Over the past 25 years, single-molecule spectroscopy has developed into a widely used tool in multiple disciplines of science. The diversity of routinely recorded emission spectra does underpin the strength of the single-molecule approach in resolving the heterogeneity and dynamics, otherwise hidden in the ensemble. In early cryogenic studies single molecules were identified by their distinct excitation spectra, yet measuring excitation spectra at room temperature remains challenging. Here we present a broadband Fourier approach that allows rapid recording of excitation spectra of individual molecules under ambient conditions and that is robust against blinking and bleaching. Applying the method we show that the excitation spectra of individual molecules exhibit an extreme distribution of solvatochromic shifts and distinct spectral shapes. Importantly, we demonstrate that the sensitivity and speed of the broadband technique is comparable to that of emission spectroscopy putting both techniques side-by-side in single-molecule spectroscopy. PMID:26794035

  10. 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 that this pulsar had a massive companion that exploded in a supernova, disrupting its orbit," McLaughlin said. Astronomers and students will work together in the coming months to find answers to these questions. The PSC is a joint project of the National Radio Astronomy Observatory and West Virginia University, funded by a grant from the National Science Foundation. The PSC, led by NRAO Education Officer Sue Ann Heatherly and Project Director Rachel Rosen, includes training for teachers and student leaders, and provides parcels of data from the GBT to student teams. The project involves teachers and students in helping astronomers analyze data from the GBT, a giant, 17-million-pound telescope. Some 300 hours of observing data were reserved for analysis by student teams. Thompson, Snider, and Mabry have been working with about 170 other students across the country. The responsibility for the work, and for the discoveries, is theirs. They are trained by astronomers and by their teachers to distinguish between pulsars and noise. The students' collective judgment sifts the pulsars from the noise. All three students had analyzed thousands of data plots before coming upon this one. Casey Thompson, who has been with the PSC for three years, has analyzed more than 30,000 plots. "Sometimes I just stop and think about the fact that I'm looking at data from space," Thompson said. "It's really special to me." In addition to this discovery, two other astronomical objects have been discovered by students. In 2009, Shay Bloxton of Summersville, WV, discovered a pulsar that spins once every four seconds, and Lucas Bolyard of Clarksburg, WV, discovered a rapidly rotating radio transient, which astronomers believe is a pulsar that emits radio waves in bursts. Those involved in the PSC hope that being a part of astronomy will give students an appreciation for science. Maybe the project will even produce some of the next generation of astronomers. Snider, surely, has been inspired. "The PSC changed my career path," confessed Thompson. "I'm going to study astrophysics." Snider is pleased with the idea of contributing to scientific knowledge. "I hope that astronomers at Green Bank and around the world can learn something from the discovery," he said. Mabry is simply awed. "We've actually been able to experience something," she said. The PSC will continue through 2011. Teachers interested in participating in the program can learn more at this link, http://www.gb.nrao.edu/epo/psc.shtml.

  11. Fast pulsed excitation wiggler or undulator

    DOEpatents

    van Steenbergen, Arie

    1990-01-01

    A fast pulsed excitation, electromagnetic undulator or wiggler, employing geometrically alternating substacks of thin laminations of ferromagnetic material, together with a single turn current loop excitation of the composite assembly, of such shape and configuration that intense, spatially alternating, magnetic fields are generated; for use as a pulsed mode undulator or wiggler radiator, for use in a Free Electron Laser (FEL) type radiation source or, for use in an Inverse Free Electron Laser (IFEL) charged particle accelerator.

  12. Electrostriction parametric excitation in dielectric resonators

    SciTech Connect

    Belokopytov, G.V.

    1988-03-01

    Electrostriction parametric excitation of electromagnetic and elastic oscillations in oscillatory systems (resonators) is studied. The threshold powers and stationary amplitudes of parametric generation are determined in two modes: when the electromagnetic oscillations of the combination frequencies occur in the same mode of the resonator as the pumping oscillations and when the electromagnetic oscillations are converted into a different mode. Numerical calculations of the threshold power for KTaO/sub 3/ microwave resonators confirm the striction nature of the excitations observed in them.

  13. 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.

  14. Remarks on Fermi liquid from holography

    SciTech Connect

    Kulaxizi, Manuela; Parnachev, Andrei

    2008-10-15

    We investigate the signatures of Fermi liquid formation in the N=4 super Yang-Mills theory coupled to fundamental hypermultiplet at nonvanishing chemical potential for the global U(1) vector symmetry. At strong 't Hooft coupling the system can be analyzed in terms of the D7-brane dynamics in the AdS{sub 5}xS{sup 5} background. The phases with vanishing and finite charge density are separated at zero temperature by a quantum phase transition. In the case of vanishing hypermultiplet mass, Karch, Son, and Starinets discovered a gapless excitation whose speed equals the speed of sound. We find that this zero sound mode persists to all values of the hypermultiplet mass, and its speed vanishes at the point of phase transition. The value of critical exponent and the ratio of the velocities of zero and first sounds are consistent with the predictions of Landau Fermi liquid theory at strong coupling.

  15. 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.

  16. Exciting threshold dependence of self-sustained spikes in excitable neurons

    NASA Astrophysics Data System (ADS)

    Wang, Jianxiong; Liu, Zonghua

    2011-07-01

    The dependence of self-sustained spikes on the exciting threshold is investigated by two neuron models with an initial stimulus. We find that in the sub-excitable regime of neuron, the exciting threshold is the key factor for an initial stimulus to induce self-sustained spikes, which is robust to the network structures. Furthermore, we even observe self-sustained spikes in a one-dimensional chain, in contrast to previous results stating that an external pacing or a loop structure is the necessary condition to sustain spikes. While in the excitable regime of neuron, we also find the effect of the exciting threshold, i.e. that the lower exciting threshold will result in strong firing synchronization but the higher threshold will result in weak firing synchronization. These findings may be helpful in understanding the microscopic mechanism of epileptic seizures.

  17. Electron excitation from ground state to first excited state: Bohmian mechanics method

    NASA Astrophysics Data System (ADS)

    Yang, Song; Shuang, Zhao; Fu-Ming, Guo; Yu-Jun, Yang; Su-Yu, Li

    2016-03-01

    The excitation process of electrons from the ground state to the first excited state via the resonant laser pulse is investigated by the Bohmian mechanics method. It is found that the Bohmian particles far away from the nucleus are easier to be excited and are excited firstly, while the Bohmian particles in the ground state is subject to a strong quantum force at a certain moment, being excited to the first excited state instantaneously. A detailed analysis for one of the trajectories is made, and finally we present the space and energy distribution of 2000 Bohmian particles at several typical instants and analyze their dynamical process at these moments. Project supported by the Doctoral Research Start-up Funding of Northeast Dianli University, China (Grant No. BSJXM-201332), the National Natural Science Foundation of China (Grant Nos. 11547114, 11534004, 11474129, 11274141, 11447192, and 11304116), and the Graduate Innovation Fund of Jilin University, China (Grant No. 2015091).

  18. 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.

  19. 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.

  20. Quenching of the Giant Dipole Resonance Strength at High Excitation Energy

    NASA Astrophysics Data System (ADS)

    Santonocito, D.; Blumenfeld, Y.; Agodi, C.; Alba, R.; Bellia, G.; Coniglione, R.; Delaunay, F.; Del Zoppo, A.; Finocchiaro, P.; Frascaria, N.; Hongmei, F.; Lima, V.; Maiolino, C.; Migneco, E.; Piattelli, P.; Sapienza, P.; Scarpaci, J. A.

    2007-05-01

    The evolution with excitation energy of the Giant Dipole Resonance features in nuclei of mass A≈108-136 is reviewed. We first discuss the results of the experiments performed with MEDEA studying the GDR gamma decay from hot nuclei populated at excitation energies above 300 MeV. The focus of the paper is on the excitation energy region between 160 and 290 MeV. This region has been investigated through the study of the reactions 116Sn + 12C at 17 and 23 A MeV, and 116Sn + 24Mg at 17 A MeV. Gamma-rays were detected using MEDEA in coincidence with evaporation residues detected in MACISTE. The analysis of the gamma-ray spectra and their comparison with statistical calculations are presented. The comparison with γ-ray spectra from the reaction 36Ar + 98Mo at higher excitation energies shows a coherent scenario where a progressive reduction of γ multiplicity relative to predictions for 100% of the Energy Weighted Sum Rule is observed above 200 MeV excitation energy. Finally, the existence of a link between disappearance of collective motion and the liquid-gas phase transitions is discussed.

  1. High Frequency Electromechanical Imaging of Ferroelectrics in a Liquid Environment

    SciTech Connect

    Jesse, Stephen; Chu, Ying-Hao; Kalinin, Sergei V

    2012-01-01

    The coupling between electrical and mechanical phenomena is a ubiquitous feature of many information and energy storage materials and devices. In addition to involvement in performance and degradation mechanisms, electromechanical effects underpin a broad spectrum of nanoscale imaging and spectroscopies including piezoresponse force and electrochemical strain microscopies. Traditionally, these studies are conducted under ambient conditions. However, applications related to imaging energy storage and electrophysiological phenomena require operation in a liquid phase and therefore the development of electromechanical probing techniques suitable to liquid environments. Due to the relative high conductivity of most liquids and liquid decomposition at low voltages, the transfer of characterization techniques from ambient to liquid is not straightforward. Here we present a detailed study of ferroelectric domain imaging and manipulation in thin film BiFeO{sub 3} using piezoresponse force microscopy in liquid environments as model systems for electromechanical phenomena in general. We explore the use of contact resonance enhancement and the application of multifrequency excitation and detection principles to overcome the experimental problems introduced by a liquid environment. Understanding electromechanical sample characterization in liquid is a key aspect not only for ferroelectric oxides but also for biological and electrochemical sample systems.

  2. Mechanical models for tanks containing two liquids

    SciTech Connect

    Tang, Y.

    1994-06-01

    The well-known Housner`s mechanical model for laterally excited rigid tanks that contain one liquid is generalized to permit consideration of tanks that contain two liquids under the horizontal and rocking base motions. Two mechanical models are developed herein; one is for rigid tanks and the other for flexible tanks. The model for rigid tanks has a rigidly attached mass and infinite number of elastically supported masses. The rigid attached mass which possesses a mass moment of inertia represents the impulsive component, whereas the elastically supported masses which do not possess mass moment of inertia represent the convective component of the response. These masses and their heights are chosen such that, under the same base motions, the base shear and base moments of the model match those of the original liquid-tank system. The spring stiffness constants for the elastically supported masses in the model are determined from the sloshing frequencies of the liquid-tank system. The model for flexible tanks, however, only represents the impulsive action of the hydrodynamic response. It has an elastically supported mass that does not possess mass moment of inertia and a member that has no mass but possesses a mass moment of inertia. This latter model is proposed for the study of the effect of the soil-structure interaction.

  3. Local energy landscape in a simple liquid

    SciTech Connect

    Iwashita, T.; Egami, Takeshi

    2014-11-26

    It is difficult to relate the properties of liquids and glasses directly to their structure because of complexity in the structure that defies precise definition. The potential energy landscape (PEL) approach is a very insightful way to conceptualize the structure-property relationship in liquids and glasses, particularly the effect of temperature and history. However, because of the highly multidimensional nature of the PEL it is hard to determine, or even visualize, the actual details of the energy landscape. In this article we introduce a modified concept of the local energy landscape (LEL), which is limited in phase space, and demonstrate its usefulness using molecular dynamics simulation on a simple liquid at high temperatures. The local energy landscape is given as a function of the local coordination number, the number of the nearest-neighbor atoms. The excitation in the LEL corresponds to the so-called β-relaxation process. The LEL offers a simple but useful starting point to discuss complex phenomena in liquids and glasses.

  4. Local energy landscape in a simple liquid

    DOE PAGESBeta

    Iwashita, T.; Egami, Takeshi

    2014-11-26

    It is difficult to relate the properties of liquids and glasses directly to their structure because of complexity in the structure that defies precise definition. The potential energy landscape (PEL) approach is a very insightful way to conceptualize the structure-property relationship in liquids and glasses, particularly the effect of temperature and history. However, because of the highly multidimensional nature of the PEL it is hard to determine, or even visualize, the actual details of the energy landscape. In this article we introduce a modified concept of the local energy landscape (LEL), which is limited in phase space, and demonstrate itsmore » usefulness using molecular dynamics simulation on a simple liquid at high temperatures. The local energy landscape is given as a function of the local coordination number, the number of the nearest-neighbor atoms. The excitation in the LEL corresponds to the so-called β-relaxation process. The LEL offers a simple but useful starting point to discuss complex phenomena in liquids and glasses.« less

  5. 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

  6. 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

  7. Sloshing displacements in a tank containing two liquids

    SciTech Connect

    Tang, Y.

    1993-06-01

    A study on the sloshing displacements in a tank containing two different liquids under a seismic excitation is presented. The gravitational effect at the interface of two liquids is considered. The problem is solved analytically. The response quantities examined include the sloshing wave height, the natural frequencies of the sloshing motion, and the vertical displacement at the interface of two liquids. It is found that there are two sloshing frequencies associated with each surface sloshing mode; the higher value of the two frequencies that associate with the fundamental sloshing mode is the dominant frequency of the surface sloshing motion, and the lower one is the dominant frequency of the interface vertical displacement. It is further shown that the maximum sloshing wave height increases significantly, and the fundamental frequency of the sloshing motion is smaller than that in an identical tank containing one liquid. The data presented are compared with those obtained by neglecting the gravitational effect at the interface to elucidate this effect.

  8. Excess dielectron in an ionic liquid as a dynamic bipolaron.

    PubMed

    Liu, Jinxiang; Wang, Zhiping; Zhang, Meng; Cukier, Robert I; Bu, Yuxiang

    2013-03-01

    We report an ab initio molecular dynamics simulation study on the accommodation of a dielectron in a pyridinium ionic liquid in both the singlet and triplet state. In contrast to water and liquid ammonia, a dielectron does not prefer to reside in cavity-shaped structures in the ionic liquid. Instead, it prefers to be distributed over more cations, with long-lived diffuse and short-lived localized distributions, and with a triplet ground state and a low-lying, open-shell singlet excited state. The two electrons evolve nonsynchronously in both states via a diffuse-versus-localized interconversion mechanism that features a dynamic bipolaron with a modest mobility, slightly lower than a hydrated electron. This work presents the first detailed study on the structures and dynamics of a dielectron in ionic liquids. PMID:23521297

  9. Liquid-crystalline nanoparticles: Hybrid design and mesophase structures

    PubMed Central

    Greget, Romain; Dominguez, Cristina; Nagy, Zsuzsanna T; Guillon, Daniel; Gallani, Jean-Louis

    2012-01-01

    Summary Liquid-crystalline nanoparticles represent an exciting class of new materials for a variety of potential applications. By combining supramolecular ordering with the fluid properties of the liquid-crystalline state, these materials offer the possibility to organise nanoparticles into addressable 2-D and 3-D arrangements exhibiting high processability and self-healing properties. Herein, we review the developments in the field of discrete thermotropic liquid-crystalline nanoparticle hybrids, with special emphasis on the relationship between the nanoparticle morphology and the nature of the organic ligand coating and their resulting phase behaviour. Mechanisms proposed to explain the supramolecular organisation of the mesogens within the liquid-crystalline phases are discussed. PMID:22509204

  10. 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).

  11. Liquid level detector

    SciTech Connect

    Tshishiku, Eugene M.

    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.

  12. Enhancing liquid jet erosion

    SciTech Connect

    Johnson V.E. Jr.

    1984-10-02

    Process and apparatus for enhancing the erosive intensity of a high velocity liquid jet when the jet is impacted against a surface for cutting, cleaning, drilling or otherwise acting on the surface. A preferred method comprises the steps of forming a high velocity liquid jet, oscillating the velocity of the jet at a preferred Strouhal number, and impinging the pulsed jet against a solid surface to be eroded. Typically the liquid jet is pulsed by oscillating the velocity of the jet mechanically or by hydrodynamic and acoustic interactions. The invention may be applied to enhance cavitation erosion in a cavitating liquid jet, or to modulate the velocity of a liquid jet, or to modulate the velocity of a liquid jet exiting in a gas, causing it to form into discrete slugs, thereby producing an intermittent percussive effect.

  13. Liquid sheet radiator apparatus

    NASA Technical Reports Server (NTRS)

    Chubb, Donald L. (Inventor)

    1990-01-01

    An external flow, liquid sheet radiator apparatus adapted for space applications has as its radiating surface a thin stable liquid sheet formed by fluid flow through a very narrow slit affixed to the sheet generator. As a result of surface tension forces, the sheet has a triangular shape and is collected into a simply designed collector positioned at the apex of the triangle. The specific power for the liquid sheet is virtually the same as the droplet sheet specific power.

  14. Ultrasonic liquid level detector

    DOEpatents

    Kotz, Dennis M.; Hinz, William R.

    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.

  15. 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.

  16. Liquid crystal optofluidics

    NASA Astrophysics Data System (ADS)

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

    2012-10-01

    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.

  17. 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.

  18. Gain narrowing and random lasing from dye-doped polymer-dispersed liquid crystals with nanoscale liquid crystal droplets

    NASA Astrophysics Data System (ADS)

    Liu, Y. J.; Sun, X. W.; Elim, H. I.; Ji, W.

    2006-07-01

    Dye-doped polymer-dispersed liquid crystals have been studied for random lasing. The dye-doped polymer-dispersed liquid crystal film was fabricated by photoinitiated polymerization with a collimated 514.5nm Ar+ laser beam. Scanning electron microscopy analysis showed that most liquid crystal droplets in polymer matrix ranged from 20to80nm. Gain narrowing and random lasing from dye-doped polymer dispersed liquid crystals were observed under the excitation of a frequency-doubled Nd:YAG (yttrium aluminum garnet) laser operating at a wavelength of 532nm. The possible mechanism was proposed to explain the random lasing. The threshold of the random lasing was about 25μJ/pulse. The linewidth of the lasing peaks was about 1nm. With the film thickness of 6.5μm, the lasing mode was nearly transverse electric polarized.

  19. Nonlinear excitations in inflationary power spectra

    NASA Astrophysics Data System (ADS)

    Miranda, Vinicius; Hu, Wayne; He, Chen; Motohashi, Hayato

    2016-01-01

    We develop methods to calculate the curvature power spectrum in models where features in the inflaton potential nonlinearly excite modes and generate high frequency features in the spectrum. The first nontrivial effect of excitations generating further excitations arises at third order in deviations from slow roll. If these further excitations are contemporaneous, the series can be resummed, showing the exponential sensitivity of the curvature spectrum to potential features. More generally, this exponential approximation provides a power spectrum template which nonlinearly obeys relations between excitation coefficients and whose parameters may be appropriately adjusted. For a large sharp step in the potential, it greatly improves the analytic power spectrum template and its dependence on potential parameters. For axionic oscillations in the potential, it corrects the mapping between the potential and the amplitude, phase and zero point of the curvature oscillations, which might otherwise cause erroneous inferences in for example the tensor-scalar ratio, formally even when that amplitude is 103 times larger than the slow-roll power spectrum. It also estimates when terms that produce double frequency oscillations that are usually omitted when analyzing data should be included. These techniques should allow future studies of high frequency features in the cosmic microwave background and large-scale structure to extend to higher amplitude and/or higher precision.

  20. Targeting individual excited states in DMRG.

    NASA Astrophysics Data System (ADS)

    Dorando, Jonathan; Hachmann, Johannes; Kin-Lic Chan, Garnet

    2007-03-01

    The low-lying excited states of π-conjugated molecules are important for the development of novel devices such as lasers, light-emitting diodes, photovoltaic cells, and field-effect transistors [1,2]. The ab-intio Density Matrix Renormalization Group (DMRG) provides a powerful way to explore the electronic structure of quasi-one-dimensional systems such as conjugated organic oligomers. However, DMRG is limited to targeting only low-lying excited states through state-averaged DMRG (SDMRG). There are several drawbacks; state-averaging degrades the accuracy of the excited states and is limited to at most a few of the low-lying states [3]. In this study, we present a new method for targeting higher individual excited states. Due to progress in the field of numerical analysis presented by Van Der Horst and others [4], we are able to target individual excited states of the Hamiltonian. This is accomplished by modifying the Jacobi-Davidson algorithm via a ``Harmonic Ritz'' procedure. We will present studies of oligoacenes and polyenes that compare the accuracy of SDMRG and Harmonic Davidson DMRG. [1] Burroughes, et al. , Nature 347, 539 (1990). [2] Shirota, J. Mater. Chem. 10, 1, (2000). [3] Ramasesha, Pati, Krishnamurthy, Shuai, Bredas, Phys. Rev. B. 54, 7598, (1997). [4] Bai, Demmel, Dongarra, Ruhe, Van Der Horst, Templates for the Solution of Algebraic Eigenvalue Problems, SIAM, 2000.

  1. 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.

  2. 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.

  3. Photoassociative Excitation Spectroscopy of Excimer Molecules

    NASA Astrophysics Data System (ADS)

    Jones, Ronald Blake

    Laser excitation spectroscopy of transitions having dissociative ground states was explored as a tool for the study of excimer molecules. Since the repulsive nature of the ground state constrains collision pairs to large internuclear transitions, bound >=ts free excitation spectra contain more structure than the bound to free fluorescence spectra for the same molecules, therefore containing more information about the potential surfaces. Unique properties of the photoassociative excitation spectroscopy technique are described which allow the dependence of the dipole transition moment on the internuclear separation (mu (R)) to be extracted in a very direct manner. Excitation spectra are presented for the B >=ts X transitions of KrF and XeI for the wavelength (lambda) interval 206 nm < lambda < 255 nm. The excitation spectra are analyzed using an iterative trial and error comparison with calculated spectra. The effect of the rotational potential is examined. Potential surfaces and the mu(R) results are given for both molecules. The possible use of the technique is then discussed for excimer molecules having predissociative upper states. Some preliminary results for KrI are given. This work required the development of a tunable VUV source, which is described.

  4. Nuclear Excitation via Auger Transitions (NEAT)

    NASA Astrophysics Data System (ADS)

    Ward, Thomas; Emery, Guy; Rasmussen, John; Karwowski, Hugon; Castaneda, Carlos

    2008-10-01

    Triggering (prompt de-excitation) of isomeric states produced in a process of coupling nuclear excitations to atomic shells via Auger transitions (NEAT) is studied. In this resonant process the nuclear transition energy between the two states must be less than the Auger transition energy. This requires the emitted Auger electron energy and the exact on-resonance nuclear excitation share the Auger transition energy. NEAT is compared to other proposed processes of nuclear excitation produced by x-rays (NEET), by electron capture (NEEC) and bound internal conversion (BIC), all of which suffer from off-resonance nuclear excitation except in those accidental cases where the energies may coincide. Estimates of the total resonance strength will be given for the case of ^182mHf which has been extensively studied theoretically. A second case, ^189Os, where NEAT processes may contribute to the nuclear resonance fluorescence (NRF) of the ground state to the 5.8hr isomeric state will also be examined as a good case for experimental verification of the NEAT process.

  5. Optical Switching of Nematic Liquid Crystal Film based on Localized Surface Plasmon Resonance

    NASA Astrophysics Data System (ADS)

    Quint, Makiko; Delgado, Silverio; Nuno, Zachary; Hirst, Linda; Ghosh, Sayantani

    2015-03-01

    We have demonstrated an all-optical technique to reversibly switch the spatial orientation of nematic liquid crystal molecules from homeotropic to planar in a few micron thick films. Our method leverages the highly localized electric fields that are generated in the near-field of a densely packed gold nanoparticle layer when the samples are excited by light resonant with the localized surface plasmon absorption. We present simulations and control measurements for off-resonance excitation, where the switching behavior is not observed. Using polarized microscopy and transmission measurements, we observe this switching over a temperature range starting several degrees below and up to the isotropic transition, and at on-resonance excitation power less than 10 μW. In addition, we controllably vary the in-plane directionality of the liquid crystal molecules in the planar state by altering the linear polarization of the incident excitation. This work is supported by NSF Grant No. DMR-1056860 and ECC-1227034.

  6. 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.

  7. 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.

  8. Ultrasonic level sensors for liquids under high pressure

    NASA Astrophysics Data System (ADS)

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

    1986-09-01

    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.

  9. Chladni Patterns in a Liquid at Microscale

    NASA Astrophysics Data System (ADS)

    Vuillermet, Gaël; Gires, Pierre-Yves; Casset, Fabrice; Poulain, Cédric

    2016-05-01

    By means of ultrathin silicon membranes excited in the low ultrasound range, we show for the first time that it is possible to form two-dimensional Chladni patterns of microbeads in liquid. Unlike the well-known effect in a gaseous environment at the macroscale, where gravity effects are generally dominant, leading particles towards the nodal regions of displacement, we show that the combined effects of an ultrathin plate excited at low frequency (yielding to subsonic waves) together with reduced gravity (arising from buoyancy) will enhance the importance of microstreaming in the Chladni problem. Here, we report that for micrometric beads larger than the inner streaming layer, the microscale streaming in the vicinity of the plate tends to gather particles in antinodal regions of vibrations yielding to patterns in good agreement with the predicted modes for a liquid-loaded plate. Interestingly, a symmetry breaking phenomenon together with the streaming can trigger movements of beads departing from one cluster to another. We show that, for higher modes, this movement can appear as a collective rotation of the beads in the manner of a "farandole."

  10. Chladni Patterns in a Liquid at Microscale.

    PubMed

    Vuillermet, Gaël; Gires, Pierre-Yves; Casset, Fabrice; Poulain, Cédric

    2016-05-01

    By means of ultrathin silicon membranes excited in the low ultrasound range, we show for the first time that it is possible to form two-dimensional Chladni patterns of microbeads in liquid. Unlike the well-known effect in a gaseous environment at the macroscale, where gravity effects are generally dominant, leading particles towards the nodal regions of displacement, we show that the combined effects of an ultrathin plate excited at low frequency (yielding to subsonic waves) together with reduced gravity (arising from buoyancy) will enhance the importance of microstreaming in the Chladni problem. Here, we report that for micrometric beads larger than the inner streaming layer, the microscale streaming in the vicinity of the plate tends to gather particles in antinodal regions of vibrations yielding to patterns in good agreement with the predicted modes for a liquid-loaded plate. Interestingly, a symmetry breaking phenomenon together with the streaming can trigger movements of beads departing from one cluster to another. We show that, for higher modes, this movement can appear as a collective rotation of the beads in the manner of a "farandole." PMID:27203325

  11. Coupling liquids acoustic velocity effects on elastic metallic bioglass properties

    NASA Astrophysics Data System (ADS)

    Metiri, W.; Hadjoub, F.; Doghmane, A.; Hadjoub, Z.

    2009-11-01

    The effect of surface acoustic wave, SAW, velocities of coupling liquids on acoustical properties of several bulk metallic glasses, BMG, has been investigated using simulation program based on acoustic microscopy. Thus, we determined variations of critical angles at which the excitation of longitudinal mode, θL and Rayleigh mode, θR occurs as a function of wave velocities in different coupling liquids, Vliq. Linear relations of the form θi =ai0 +βiVliq were deduced. The importance of such formula, used with Snell's law, lies in the direct determination of SAW velocities and consequently mechanical properties of BMGs.

  12. Radiation chemical effects of X-rays on liquids

    SciTech Connect

    Holroyd, R.A.; Preses, J.M.

    1998-11-01

    This review describes some of the chemical changes induced by photoelectrons which are released in liquids when X-rays are absorbed. Both experimental studies and theory are discussed. In part 1, the basic processes occurring upon absorption of X-rays are described. Parts 2 and 3 deal with hydrocarbon liquids; in part 2 the ion yields, including effects at K-edges, and in part 3, the yields of excited states. Part 4 discusses chemical effects of X-rays in aqueous solutions. The authors end with a summary of future needs and directions.

  13. 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

  14. Patterns of conductivity in excitable automata with updatable intervals of excitations.

    PubMed

    Adamatzky, Andrew

    2012-11-01

    We define a cellular automaton where a resting cell excites if number of its excited neighbors belong to some specified interval and boundaries of the interval change depending on ratio of excited and refractory neighbors in the cell's neighborhood. We calculate excitability of a cell as a number of possible neighborhood configurations that excite the resting cell. We call cells with maximal values of excitability conductive. In exhaustive search of functions of excitation interval updates we select functions which lead to formation of connected configurations of conductive cells. The functions discovered are used to design conductive, wirelike, pathways in initially nonconductive arrays of cells. We demonstrate that by positioning seeds of growing conductive pathways it is possible to implement a wide range of routing operations, including reflection of wires, stopping wires, formation of conductive bridges, and generation of new wires in the result of collision. The findings presented may be applied in designing conductive circuits in excitable nonlinear media, reaction-diffusion chemical systems, neural tissue, and assemblies of conductive polymers. PMID:23214841

  15. Work excitement in nursing: an examination of the relationship between work excitement and burnout.

    PubMed

    Sadovich, Juliana M

    2005-01-01

    The results of this study found a significant relationship between burnout and the Work Excitement Model. This suggests that utilization of the Work Excitement Model by health care organizations may reduce nursing burnout and improve productivity and quality of care. PMID:15881495

  16. Self-excitation of surface plasmon polaritons

    NASA Astrophysics Data System (ADS)

    Bordo, V. G.

    2016-04-01

    The novel effect of self-excitation of surface plasmons (SESP) in a plasmonic nanocavity is predicted, and its theory is developed from first principles. It is assumed that the cavity is formed by a nanogap between two metals and contains polarizable inclusions. Basing on the dyadic Green's function of the structure, the equations for the field in the cavity are investigated. It is shown that under certain conditions the field becomes unstable that leads to its self-excitation. The threshold criterion for self-excitation as well as the frequency of self-oscillation are derived in an analytical form. The SESP effect is explained in terms of a positive feedback for the polarization of inclusions provided by the field reflected from the cavity walls. These findings suggest a principally new avenue to surface plasmon generation which does not employ stimulated emission and is different from SPASER or plasmon laser.

  17. On modulations of the Chandler wobble excitation

    NASA Astrophysics Data System (ADS)

    Zotov, L.; Bizouard, C.

    2012-12-01

    We derive the Chandler wobble excitation from the polar motion (PM) observations by using the Panteleev corrective filtering. The latter method is based on inversion of the Euler-Liouville equation, with additional filtering in the Chandler frequency band. The excitation reconstruction reveals amplitude changes different from the one observed in the Chandler wobble itself. Their main feature, well observable over the length of the day (LOD), is the presence of a 18.6-year amplitude modulation synchronous with the lunar orbital precession cycle and tidal effects. The filtering of oceanic and atmospheric excitation in the Chandler frequency band also reveals a coherent 18.6-year oceanic pattern. Most probably the ocean provide a channel for the tidal energy transfer.

  18. 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.

  19. Experimental uncertainty associated with traveling wave excitation

    NASA Astrophysics Data System (ADS)

    Cox, Geofrey S.

    This dissertation research produces the experimental techniques required to evaluate mistuning in any rotor. Within operation, a rotor is subjected to a unique pattern of frequencies acting to excite the rotor. Utilizing traveling wave excitation, a rotor's critical frequencies and the respective excitation pattern are reproduced. Individual rotor blade frequency response functions are evaluated and statistically analyzed. The experimental results serve to not only verify the degree to which a rotor is mistuned, but also to provide an indication of the forced response amplification the mistuning induces. Within the experiment, definitive specifications were developed to ensure peak rotor responses. Numerical simulations of the experiment were performed in ANSYS using a model developed by way of structured light scanning. With experimental and numerical eigenvalue differences of less than 1%, the unique modeling technique, capturing a rotor's geometric mistuning, is a valid method to predict a rotor's natural frequencies. Furthermore these same numerical results serve to validate the experimental free boundary assumption.

  20. Testing the excitability of human motoneurons

    PubMed Central

    McNeil, Chris J.; Butler, Jane E.; Taylor, Janet L.; Gandevia, Simon C.

    2013-01-01

    The responsiveness of the human central nervous system can change profoundly with exercise, injury, disuse, or disease. Changes occur at both cortical and spinal levels but in most cases excitability of the motoneuron pool must be assessed to localize accurately the site of adaptation. Hence, it is critical to understand, and employ correctly, the methods to test motoneuron excitability in humans. Several techniques exist and each has its advantages and disadvantages. This review examines the most common techniques that use evoked compound muscle action potentials to test the excitability of the motoneuron pool and describes the merits and limitations of each. The techniques discussed are the H-reflex, F-wave, tendon jerk, V-wave, cervicomedullary motor evoked potential (CMEP), and motor evoked potential (MEP). A number of limitations with these techniques are presented. PMID:23630483