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1

Luttinger-liquid behaviour in carbon nanotubes  

NASA Astrophysics Data System (ADS)

Electron transport in conductors is usually well described by Fermi-liquid theory, which assumes that the energy states of the electrons near the Fermi level EF are not qualitatively altered by Coulomb interactions. In one-dimensional systems, however, even weak Coulomb interactions cause strong perturbations. The resulting system, known as a Luttinger liquid, is predicted to be distinctly different from its two- and three-dimensional counterparts. For example, tunnelling into a Luttinger liquid at energies near the Fermi level is predicted to be strongly suppressed, unlike in two- and three-dimensional metals. Experiments on one-dimensional semiconductor wires, have been interpreted by using Luttinger-liquid theory, but an unequivocal verification of the theoretical predictions has not yet been obtained. Similarly, the edge excitations seen in fractional quantum Hall conductors are consistent with Luttinger-liquid behaviour, , but recent experiments failed to confirm the predicted relationship between the electrical properties of the bulk state and those of the edge states. Electrically conducting single-walled carbon nanotubes (SWNTs) represent quantum wires that may exhibit Luttinger-liquid behaviour, . Here we present measurements of the conductance of bundles (`ropes') of SWNTs as a function of temperature and voltage that agree with predictions for tunnelling into a Luttinger liquid. In particular, we find that the conductance and differential conductance scale as power laws with respect to temperature and bias voltage, respectively, and that the functional forms and the exponents are in good agreement with theoretical predictions.

Bockrath, Marc; Cobden, David H.; Lu, Jia; Rinzler, Andrew G.; Smalley, Richard E.; Balents, Leon; McEuen, Paul L.

1999-02-01

2

Spectral properties of Luttinger liquids: A comparative analysis of regular, helical, and spiral Luttinger liquids  

NASA Astrophysics Data System (ADS)

We provide analytic expressions for the Green's functions in position-frequency space as well as for the tunneling density of states of various Luttinger liquids at zero temperature: the standard spinless and spinful Luttinger liquids, the helical Luttinger liquid at the edge of a topological insulator, and the Luttinger liquid that appears either together with an ordering transition of nuclear spins in a one-dimensional conductor or in spin-orbit split quantum wires in an external magnetic field. The latter system is often used to mimic a helical Luttinger liquid, yet we show here that it exhibits significantly different response functions and, to discriminate, we call it the spiral Luttinger liquid. We give fully analytic results for the tunneling density of state of all the Luttinger liquids as well as for most of the Green's functions. The remaining Green's functions are expressed by simple convolution integrals between analytic results.

Braunecker, Bernd; Bena, Cristina; Simon, Pascal

2012-01-01

3

Detection of entanglement by helical Luttinger liquids  

NASA Astrophysics Data System (ADS)

A Cooper-pair or electron-hole splitter is a device capable of spatially separating entangled fermionic quasiparticles into mesoscopic solid-state systems such as quantum dots or quantum wires. We theoretically study such a splitter based on a pair of helical Luttinger liquids, which arise naturally at the edges of a quantum spin Hall insulator. Equipping each helical liquid with a beam splitter, current-current cross correlations can be used to construct a Bell inequality whose violation would indicate nonlocal orbital entanglement of the injected electrons and/or holes. Due to the Luttinger-liquid correlations, however, the entanglement is suppressed depending on ambient temperature and voltage bias.

Sato, Koji; Tserkovnyak, Yaroslav

2014-07-01

4

Compressible Strips, Chiral Luttinger Liquids, and All That Jazz  

NASA Astrophysics Data System (ADS)

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.

MacDonald, A. H.

1996-03-01

5

Non-equilibrium Luttinger liquids Alexander D. Mirlin  

E-print Network

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

Fominov, Yakov

6

Brownian scattering of a spinon in a Luttinger liquid  

NASA Astrophysics Data System (ADS)

We consider strongly interacting one-dimensional electron liquids where elementary excitations carry either spin or charge. At small temperatures a spinon created at the bottom of its band scatters off low-energy spin and charge excitations and follows the diffusive motion of a Brownian particle in momentum space. We calculate the mobility characterizing these processes and show that the resulting diffusion coefficient of the spinon is parametrically enhanced at low temperatures compared to that of a mobile impurity in a spinless Luttinger liquid. We briefly discuss that this hints at the relevance of spin in the process of equilibration of strongly interacting one-dimensional electrons, and comment on implications for transport in clean single-channel quantum wires.

Rieder, M.-T.; Levchenko, A.; Micklitz, T.

2014-12-01

7

Energy transport in Heisenberg chains beyond the Luttinger liquid paradigm  

NASA Astrophysics Data System (ADS)

We study the energy transport between two interacting spin chains which are initially separated, held at different temperatures, and subsequently put in contact. We consider the spin-1/2 XXZ model in the gapless regime and exploit its integrability properties to formulate an analytical ansatz for the nonequilibrium steady state even at temperatures where the low-energy Luttinger liquid description is not accurate. We apply our method to compute the steady energy current and benchmark it both with the known low-energy limit and at higher temperatures with numerical simulations. We find an excellent agreement even at high temperatures, where the Luttinger liquid prediction is shown to fail.

De Luca, Andrea; Viti, Jacopo; Mazza, Leonardo; Rossini, Davide

2014-10-01

8

The Luttinger liquid concept for interacting electrons in one dimension  

NASA Astrophysics Data System (ADS)

The theoretical description of interacting fermions in one spatial dimension is simplified by the fact that the low-energy spectrum of noninteracting fermions is identical to the one for a harmonic chain. This allows us to describe interacting fermions as a system of coupled oscillators. The exact solution of the Tomonaga-Luttinger model is discussed and results for the momentum distribution and spectral functions are presented. The general Luttinger liquid phenomenology is briefly discussed and various attempts at the experimental verification of the theoretical predictions are examined. Extended defects in semiconductors might also be candidate systems.

Schnhammer, K.

2002-12-01

9

Atomically controlled quantum chains hosting a Tomonaga-Luttinger liquid  

NASA Astrophysics Data System (ADS)

Atom assemblies on surfaces represent the ultimate lower size limit for electronic circuits, and their conduction properties are governed by quantum phenomena. A fundamental prediction for a line of atoms confining the electrons to one dimension is the Tomonaga-Luttinger liquid. Yet, astonishingly, this has not been observed in surface systems so far. Here we scrutinize self-organized chains of single-atom width by scanning tunnelling spectroscopy and photoemission. The low-energy spectra univocally show power-law behaviour. Even more, the density of states obeys universal scaling with energy and temperature. This demonstrates paradigmatic Tomonaga-Luttinger liquid properties encountered at the atomic scale, with bearing for the conductivity of wires and junctions. Local control enables us to study modified interactions due to defects or bridging atoms not previously possible.

Blumenstein, C.; Schfer, J.; Mietke, S.; Meyer, S.; Dollinger, A.; Lochner, M.; Cui, X. Y.; Patthey, L.; Matzdorf, R.; Claessen, R.

2011-10-01

10

Luttinger-liquid behavior of one-dimensional 3He  

NASA Astrophysics Data System (ADS)

The ground-state properties of one-dimensional 3He are studied using quantum Monte Carlo methods. The equation of state is calculated in a wide range of physically relevant densities and is well interpolated by a power-series fit. The Luttinger liquid theory is found to describe the long-range properties of the correlation functions. The density dependence of the Luttinger parameter is explicitly found, and interestingly it shows a nonmonotonic behavior. Depending on the density, the static structure factor can be a smooth function of the momentum or might contain a peak of a finite or infinite height. Although no phase transitions are present in the system, we identify a number of physically different regimes, including an ideal Fermi gas, a "Bose gas." a "super-Tonks-Girardeau" regime, and a "quasicrystal." The obtained results are applicable to unpolarized, partially, or fully polarized 3He.

Astrakharchik, G. E.; Boronat, J.

2014-12-01

11

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

PubMed

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

Levchenko, Alex

2014-11-01

12

Detection of Spin Entanglement via Spin-Charge Separation in Crossed Tomonaga-Luttinger Liquids  

NASA Astrophysics Data System (ADS)

We investigate tunneling between two spinful Tomonaga-Luttinger liquids (TLLs) realized, e.g., as two crossed nanowires or quantum Hall edge states. When injecting into each TLL one electron of opposite spin, the dc current measured after the crossing differs for singlet, triplet, or product states. This is a striking new non-Fermi liquid feature because the (mean) current in a noninteracting beam splitter is insensitive to spin entanglement. It can be understood in terms of collective excitations subject to spin-charge separation. This behavior may offer an easier alternative to traditional entanglement detection schemes based on current noise, which we show to be suppressed by the interactions.

Schroer, Alexander; Braunecker, Bernd; Levy Yeyati, Alfredo; Recher, Patrik

2014-12-01

13

Plasmon Decay and Thermal Transport from Spin-Charge Coupling in Generic Luttinger Liquids  

NASA Astrophysics Data System (ADS)

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.

Levchenko, Alex

2014-11-01

14

PHYSICAL REVIEW B 85, 035136 (2012) Spectral properties of Luttinger liquids: A comparative analysis of regular, helical, and  

E-print Network

insulators,3­5 in 1D semiconductor wires with strong spin-orbit interaction in an external magnetic field at zero temperature: the standard spinless and spinful Luttinger liquids, the helical Luttinger liquid at the edge of a topological insulator, and the Luttinger liquid that appears either together with an ordering

Braunecker, Bernd

15

Spin and charge currents and current rectification in Luttinger liquids  

NASA Astrophysics Data System (ADS)

Asymmetries in spin and charge transport properties are of great interest for spintronic and electronic applications. We show that externally-driven spin and charge currents in a Luttinger liquid model of a one-dimensional quantum wire are strongly modified by the presence of a localized magnetic or nonmagnetic scatterer. A diode effect appears at low voltages when this scatterer is spatially asymmetric, and a non-monotonous dependence of the current on the voltage is possible. D.E. Feldman, S. Scheidl, and V. M. Vinokur, Phys. Rev. Lett. 94, 186809 (2005); B. Braunecker, D. E. Feldman, and J. B. Marston, Phys. Rev. B 72, 125311 (2005)

Braunecker, B.; Feldman, D. E.; Marston, J. B.

2006-03-01

16

Quantum Hall Edge Physics and its One-Dimensional Luttinger Liquid Description  

NASA Astrophysics Data System (ADS)

We describe the relationship between quantum Hall edge states and the one-dimensional Luttinger liquid model. The Luttinger liquid model originated from studies of one-dimensional Fermi systems, however, it results that many ideas inspired by such a model can find applications to phenomena occurring even in higher dimensions. Quantum Hall systems which essentially are correlated two-dimensional electronic systems in a strong perpendicular magnetic field have an edge. It turns out that the quantum Hall edge states can be described by a one-dimensional Luttinger model. In this work, we give a general background of the quantum Hall and Luttinger liquid physics and then point out the relationship between the quantum Hall edge states and its one-dimensional Luttinger liquid representation. Such a description is very useful given that the Luttinger liquid model has the property that it can be bosonized and solved. The fact that we can introduce a simpler model of noninteracting bosons, even if the quantum Hall edge states of electrons are interacting, allows one to calculate exactly various quantities of interest. One such quantity is the correlation function which, in the asymptotic limit, is predicted to have a power law form. The Luttinger liquid model also suggests that such a power law exponent should have a universal value. A large number of experiments have found the quantum Hall edge states to show behavior consistent with a Luttinger liquid description. However, while a power law dependence of the correlation function has been observed, the experimental values of the exponent appear not to be universal. This discrepancy might be due to various correlation effects between electrons that sometimes are not easy to incorporate within a standard Luttinger liquid model.

Ciftja, Orion

2014-10-01

17

Luttinger Liquid, Singular Interaction and Quantum Criticality in Cuprate Materials  

NASA Astrophysics Data System (ADS)

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.

di Castro, C.; Caprara, S.

2014-10-01

18

Detection of Spin Entanglement via Spin-Charge Separation in Crossed Tomonaga-Luttinger Liquids.  

PubMed

We investigate tunneling between two spinful Tomonaga-Luttinger liquids (TLLs) realized, e.g., as two crossed nanowires or quantum Hall edge states. When injecting into each TLL one electron of opposite spin, the dc current measured after the crossing differs for singlet, triplet, or product states. This is a striking new non-Fermi liquid feature because the (mean) current in a noninteracting beam splitter is insensitive to spin entanglement. It can be understood in terms of collective excitations subject to spin-charge separation. This behavior may offer an easier alternative to traditional entanglement detection schemes based on current noise, which we show to be suppressed by the interactions. PMID:25615359

Schroer, Alexander; Braunecker, Bernd; Levy Yeyati, Alfredo; Recher, Patrik

2014-12-31

19

Scaling of temporal correlations in an attractive Tomonaga-Luttinger spin liquid  

NASA Astrophysics Data System (ADS)

We report temperature-dependent neutron scattering measurements of the local dynamic structure factor in the quantum spin ladder (C7H10N) 2CuBr4 in a magnetic field H =9 T, in its gapless quantum-critical phase. We show that the measured quantity has a scaling form consistent with expectations for a Tomonaga-Luttinger liquid with attraction. The measured Luttinger parameter K ?1.25 and scaling function are in excellent agreement with density matrix renormalization group numerical calculations for the underlying spin Hamiltonian.

Povarov, K. Yu.; Schmidiger, D.; Reynolds, N.; Bewley, R.; Zheludev, A.

2015-01-01

20

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

SciTech Connect

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.

Dalmonte, M. [Dipartimento di Fisica dell'Universita di Bologna and INFN, via Irnerio 46, 40127 Bologna (Italy); IQOQI and Institute for Theoretical Physics, University of Innsbruck, A-6020 Innsbruck (Austria); Pupillo, G. [IQOQI and Institute for Theoretical Physics, University of Innsbruck, A-6020 Innsbruck (Austria); Zoller, P. [IQOQI and Institute for Theoretical Physics, University of Innsbruck, A-6020 Innsbruck (Austria); Norman Bridge Laboratory of Physics 12-33, California Institute of Technology, Pasadena, California 91125 (United States)

2010-10-01

21

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

NASA Astrophysics Data System (ADS)

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 Rnyi 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.

Dra, Balzs

2014-12-01

22

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

NASA Astrophysics Data System (ADS)

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

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

2013-03-01

23

Duality between different geometries of a resonant level in a Luttinger liquid.  

PubMed

We prove an exact duality between the side-coupled and embedded geometries of a single level quantum dot attached to a quantum wire in a Luttinger liquid phase by a tunneling term and interactions. This is valid even in the presence of a finite bias voltage. Under this relation the Luttinger liquid parameter g goes into its inverse, and transmittance maps onto reflectance. We then demonstrate how this duality is revealed by the transport properties of the side-coupled case. Conductance is found to exhibit an antiresonance as a function of the level energy, whose width vanishes (enhancing transport) as a power law for low temperature and bias voltage whenever g > 1, and diverges (suppressing transport) for g < 1. On-resonance transmission is always destroyed, unless g is large enough. PMID:20366441

Goldstein, Moshe; Berkovits, Richard

2010-03-12

24

Crossover from Luttinger- to Fermi-Liquid Behavior in Strongly Anisotropic Systems in Large Dimensions  

Microsoft Academic Search

We consider the low-energy region of an array of Luttinger liquids coupled by a weak interchain hopping. The leading-logarithmic divergences can be resummed to all orders, within a self-consistent perturbative expansion in the hopping, in the large-dimension limit. The anomalous exponent scales to zero below the one-particle crossover temperature. As a consequence, coherent quasiparticles with finite weight appear along the

Enrico Arrigoni

1999-01-01

25

Effect of interactions on the noise of chiral Luttinger liquid systems  

SciTech Connect

We analyze the current noise, generated at a quantum point contact in fractional quantum Hall edge state devices, using the chiral Luttinger liquid model with an impurity and the associated exact field theoretic solution. We demonstrate that an experimentally relevant regime of parameters exists where the noise coincides with the partition noise of independent Laughlin quasiparticles. However, outside of this regime, this independent particle picture breaks down and the inclusion of interaction effects is essential to understand the shot noise.

Trauzettel, B. [Laboratoire de Physique des Solides, Universite Paris-Sud, 91405 Orsay (France); Physikalisches Institut, Albert-Ludwigs-Universitaet, 79104 Freiburg (Germany); Roche, P. [Service de Physique de l'Etat Condense, CEA Saclay, 91191 Gif-sur-Yvette (France); Glattli, D.C. [Service de Physique de l'Etat Condense, CEA Saclay, 91191 Gif-sur-Yvette (France); Laboratoire Pierre Aigrain, Departement de Physique de l'Ecole Normale Superieure, 75231 Paris (France); Saleur, H. [Physikalisches Institut, Albert-Ludwigs-Universitaet, 79104 Freiburg (Germany); Department of Physics, University of Southern California, Los Angeles, California 90089-0484 (United States); Service de Physique Theorique, CEA Saclay, 91191 Gif-sur-Yvette (France)

2004-12-15

26

Thermal Dephasing in the Laughlin Quasiparticle Interferometer: Chiral Luttinger Liquid Behavior  

Microsoft Academic Search

We report experimental temperature dependence of the amplitude of\\u000aAharonov-Bohm oscillations in the Laughlin quasiparticle interferometer. The\\u000aresults fit very well the thermal dephasing dependence predicted for a g = 1\\/3\\u000achiral Luttinger liquid interferometer, and are clearly distinct from the\\u000aactivated behavior observed in single-particle resonant tunneling and Coulomb\\u000ablockade devices. The small deviation from the zero-bias theory seen

F. E. Camino; W. Zhou; V. J. Goldman

2005-01-01

27

Thermal Dephasing in the Laughlin Quasiparticle Interferometer: Chiral Luttinger Liquid Behavior  

Microsoft Academic Search

We report experimental temperature dependence of the amplitude of Aharonov-Bohm oscillations in the Laughlin quasiparticle interferometer. The results fit very well the thermal dephasing dependence predicted for a g = 1\\/3 chiral Luttinger liquid interferometer, and are clearly distinct from the activated behavior observed in single-particle resonant tunneling and Coulomb blockade devices. The small deviation from the zero-bias theory seen

F. E. Camino; W. Zhou; V. J. Goldman

2005-01-01

28

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

NASA Astrophysics Data System (ADS)

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

Hattori, K.; Rosch, A.

2014-09-01

29

Density functionals not based on the electron gas: local-density approximation for a Luttinger liquid.  

PubMed

By shifting the reference system for the local-density approximation (LDA) from the electron gas to other model systems, one obtains a new class of density functionals, which by design account for the correlations present in the chosen reference system. This strategy is illustrated by constructing an explicit LDA for the one-dimensional Hubbard model. While the traditional ab initio LDA is based on a Fermi liquid (the three-dimensional interacting electron gas), this one is based on a Luttinger liquid. First applications to inhomogeneous Hubbard models, including one containing a localized impurity, are reported. PMID:12731934

Lima, N A; Silva, M F; Oliveira, L N; Capelle, K

2003-04-11

30

Stability of the Tomonaga-Luttinger liquid state in gamma-irradiated carbon nanotube bundles  

NASA Astrophysics Data System (ADS)

We report experimental results for the changes in conductivity of single-wall carbon nanotube bundles when irradiated by 60Co ?-rays in various environments. In the current study the samples investigated were irradiated in hermetic cells, either evacuated (0.1 Pa) or filled with hydrogen or deuterium at atmospheric pressure. In situ measurements of the resistance change as a function of irradiation dose at room temperature are presented. It was found that, for all irradiation conditions, the normalized resistance versus irradiation dose demonstrates a logarithmic behaviour. A phenomenological model for the observed dependence is derived. The current-voltage characteristics of the irradiated samples were measured in the temperature range from 4.5 to 300 K using short (10 ns) electric pulses, and the results demonstrate a scaling behaviour. This scaling occurs in the universal coordinates that correspond to the Tomonaga-Luttinger liquid concept. Our results confirm the existence of the Tomonaga-Luttinger liquid phase up to room temperature in carbon nanotubes after ?-irradiation to a dose of 5 107 rad in vacuum, 1.7 107 rad in hydrogen and 1.24 108 rad in deuterium.

Danilchenko, B. A.; Tripachko, N. A.; Voitsihovska, E. A.; Yaskovets, I. I.; Uvarova, I. Y.; Sundqvist, B.

2013-11-01

31

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

NASA Astrophysics Data System (ADS)

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

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

2014-12-01

32

Continuous matrix product states for coupled fields: Application to Luttinger liquids and quantum simulators  

NASA Astrophysics Data System (ADS)

We present a way of constructing continuous matrix product states (cMPS) for coupled fields. The cMPS is a variational ansatz for the ground state of quantum field theories in one dimension. Our proposed scheme is based on a physical interpretation in which the cMPS class can be produced by means of a dissipative dynamic of a system interacting with a bath. We study the case of coupled bosonic fields. We test the method with previous DMRG results in coupled Lieb-Liniger models. Besides, we discuss a novel application for characterizing the Luttinger liquid theory emerging in the low-energy regime of these theories. Finally, we propose a circuit QED architecture as a quantum simulator for coupled fields.

Quijandra, Fernando; Garca-Ripoll, Juan Jos; Zueco, David

2014-12-01

33

Time-resolved transport properties of a Y junction of Tomonaga-Luttinger liquid wires  

NASA Astrophysics Data System (ADS)

We study time-resolved transport properties of a Y junction composed of interacting one-dimensional quantum wires using a bosonization approach. In particular, we investigate the ac conductivity of the Y junction formed from finite-length Tomonaga-Luttinger liquid wires based on a plasmon scattering approach for injected charge pulses of arbitrary shapes. In addition, we calculate the tunneling current and quantum noise of the Y junction arising from pointlike tunneling impurities at the junction, including finite-temperature effects. Our results will be useful for designing nanoelectronic quantum circuits and for interpreting time-resolved experiments [Kamata et al., Nat. Nanotechnol. 9, 177 (2014), 10.1038/nnano.2013.312] in interacting wires and their junctions.

Agarwal, Amit

2014-11-01

34

Particle-hole symmetry and Luttinger liquids in a quantum Hall circuit  

NASA Astrophysics Data System (ADS)

I shall present recent experimental results on edge-state transport through quantum point contacts in the quantum Hall (QH) regime. Finite-bias backscattering measurements between edge channels at filling factor ?=1 will be presented at different temperatures. Transport through the constriction displays a non-linear Luttinger-like behavior even in the integer QH regime in contrast with the linear tunneling predicted for integer edge states [1,2]. Both zero-bias enhancement and suppression of the inter-edge tunneling will be shown in a controllable way as a function of gate bias [2,3,4]. The observed evolution is connected to the local charge depletion in the constriction region and offers new insight into the link between QH charge-conjugation and Luttinger liquid description of edge channels [2]. I shall discuss the relevance of these experimental results in the context of the dynamics of the highly-correlated edge channels in the fractional QH regime [5]. Finally I shall demonstrate how charge-conjugation can be exploited in the design of new QH circuits where the transport properties of the hole component of a partially filled Landau level can be directly addressed. [1] X.-G. Wen, Phys. Rev. Lett. 62, 2206 (1990); P. Fendley et al. Phys. Rev. Lett. 74, 3005 (1995). [2] S. Roddaro, V. Pellegrini, F. Beltram, L. N. Pfeiffer, K. W. West, Phys. Rev. Lett. 95, 156804 (2005). [3] S. Roddaro, V. Pellegrini, F. Beltram, G. Biasiol, L. Sorba., Phys. Rev. Lett. 93, 046801 (2004). [4] S. Roddaro, V. Pellegrini, F. Beltram, G. Biasiol, L. Sorba, R. Raimondi, G. Vignale, Phys. Rev. Lett. 90, 046805 (2003). [5] A. M. Chang, Rev. Mod. Phys. 75, 1449 (2003).

Roddaro, Stefano

2006-03-01

35

Chiral Y junction of Luttinger liquid wires at strong coupling: Fermionic representation  

NASA Astrophysics Data System (ADS)

We calculate the conductances of a three-terminal junction setup of spinless Luttinger liquid wires threaded by a magnetic flux, allowing for different interaction strength g3?g in the third wire. We employ the fermionic representation in the scattering state picture, allowing for a direct calculation of the linear response conductances, without the need of introducing contact resistances at the connection points to the outer ideal leads. The matrix of conductances is parametrized by three variables. For these we derive coupled renormalization group (RG) equations, by summing up infinite classes of contributions in perturbation theory. The resulting general structure of the RG equations may be employed to describe junctions with an arbitrary number of wires and arbitrary interaction strength in each wire. The fixed point structure of these equations (for the chiral Y junction) is analyzed in detail. For repulsive interaction (g,g3>0) there is only one stable fixed point, corresponding to the complete separation of the wires. For attractive interaction (g<0 and/or g3<0) four fixed points are found, the stability of which depends on the interaction strength. We confirm our previous weak-coupling result of lines of fixed points for special values of the interaction parameters reaching into the strong-coupling domain. We find new fixed points not discussed before, even at the symmetric line g=g3, at variance with the results of M. Oshikawa [J. Stat. Mech.1742-546810.1088/1742-5468/2006/02/P02008 (2006) P02008]. The pair-tunneling phenomenon conjectured by the latter authors is not found by us.

Aristov, D. N.; Wlfle, P.

2013-08-01

36

Luttinger-volume violating Fermi liquid in the pseudogap phase of the cuprate superconductors  

E-print Network

Based on the NMR measurements on Bi[subscript 2]Sr[subscript 2?x]La[subscript x]CuO[subscript 6+?] (La-Bi2201) in strong magnetic fields, we identify the nonsuperconducting pseudogap phase in the cuprates as a Luttinger-volume ...

Mei, Jiawei

37

An Expanded Luttinger Model  

NASA Astrophysics Data System (ADS)

This paper generalizes Luttinger's model by introducing curvature (d2?(k)/dk2 ? 0) into the kinetic energy. An exact solution for arbitrary interactions is still possible in principle, but it now requires disentangling the eigenvalue spectrum of an harmonic string of interacting boson fields at each value of q. The additional boson fields, extracted from the excitation spectrum of the Fermi sea, are self-selected according to the nature and strength of the dispersion.

Mattis, Daniel C.

2014-10-01

38

Dimensional Phase Transition from an Array of 1D Luttinger Liquids to a 3D Bose-Einstein Condensate  

NASA Astrophysics Data System (ADS)

We study the thermodynamic properties of a 2D array of coupled one-dimensional Bose gases. The system is realized with ultracold bosonic atoms loaded in the potential tubes of a two-dimensional optical lattice. For negligible coupling strength, each tube is an independent weakly interacting 1D Bose gas featuring Tomonaga Luttinger liquid behavior. By decreasing the lattice depth, we increase the coupling strength between the 1D gases and allow for the phase transition into a 3D condensate. We extract the phase diagram for such a system and compare our results with theoretical predictions. Because of the high effective mass across the periodic potential and the increased 1D interaction strength, the phase transition is shifted to large positive values of the chemical potential. Our results are prototypical to a variety of low-dimensional systems, where the coupling between the subsystems is realized in a higher spatial dimension such as coupled spin chains in magnetic insulators.

Vogler, Andreas; Labouvie, Ralf; Barontini, Giovanni; Eggert, Sebastian; Guarrera, Vera; Ott, Herwig

2014-11-01

39

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

SciTech Connect

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.

Guan, X. W.; Lee, J.-Y. [Department of Theoretical Physics, Research School of Physics and Engineering, Australian National University, Canberra ACT 0200 (Australia); Batchelor, M. T. [Department of Theoretical Physics, Research School of Physics and Engineering, Australian National University, Canberra ACT 0200 (Australia); Mathematical Sciences Institute, Australian National University, Canberra ACT 0200 (Australia); Yin, X.-G.; Chen Shu [Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China)

2010-08-15

40

VOLUME 77, NUMBER 25 P H Y S I C A L R E V I E W L E T T E R S 16 DECEMBER 1996 Mesoscopic Effects in the Fractional Quantum Hall Regime: Chiral Luttinger Liquid  

E-print Network

VOLUME 77, NUMBER 25 P H Y S I C A L R E V I E W L E T T E R S 16 DECEMBER 1996 Mesoscopic Effects in the Fractional Quantum Hall Regime: Chiral Luttinger Liquid versus Fermi Liquid Michael R. Geller, Daniel Loss

Geller, Michael R.

41

Elementary excitations and crossover phenomenon in liquids.  

PubMed

The elementary excitations of vibration in solids are phonons. But in liquids phonons are extremely short lived and marginalized. In this Letter through classical and ab initio molecular dynamics simulations of the liquid state of various metallic systems we show that different excitations, the local configurational excitations in the atomic connectivity network, are the elementary excitations in high temperature metallic liquids. We also demonstrate that the competition between the configurational excitations and phonons determines the so-called crossover phenomenon in liquids. These discoveries open the way to the explanation of various complex phenomena in liquids, such as fragility and the rapid increase in viscosity toward the glass transition, in terms of these excitations. PMID:25167427

Iwashita, T; Nicholson, D M; Egami, T

2013-05-17

42

Elementary Excitations and Crossover Phenomenon in Liquids  

NASA Astrophysics Data System (ADS)

The elementary excitations of vibration in solids are phonons. But in liquids phonons are extremely short lived and marginalized. In this Letter through classical and ab initio molecular dynamics simulations of the liquid state of various metallic systems we show that different excitations, the local configurational excitations in the atomic connectivity network, are the elementary excitations in high temperature metallic liquids. We also demonstrate that the competition between the configurational excitations and phonons determines the so-called crossover phenomenon in liquids. These discoveries open the way to the explanation of various complex phenomena in liquids, such as fragility and the rapid increase in viscosity toward the glass transition, in terms of these excitations.

Iwashita, T.; Nicholson, D. M.; Egami, T.

2013-05-01

43

Transversely excited liquid crystal cells  

Microsoft Academic Search

The integration of photorefractive liquid crystal beam coupling devices into optical systems is often hampered by the need to tilt the liquid crystal cells to high angles of incidence in order to obtain efficient beam coupling. Owing to poor charge diffusion in most liquid crystal systems, charge migration depends mainly on an externally applied drift field. Conventional cells, with electrodes

Gary Cook; Jason P. Duignan; Lesley L. Taylor

2002-01-01

44

Interaction effects in conductance of quasi-1D channels formed from AlGaAs/GaAs 2DEG: Crossover from weakly-disordered Fermi liquid to Luttinger liquid  

NASA Astrophysics Data System (ADS)

We investigated the conductance of a long and narrow high-mobility channel and observed crossover from weakly-disordered multi-channel Fermi liquid [1] to Luttinger liquid with decreasing channel width to 100nm. Quasi-one-dimensional channels were formed from an AlGaAs/GaAs heterostructure using the split-gate technique. The lengths of the channels were 100 ?m. The width of the channels were varied from a lithographic width of 500 nm to 50 nm by applying negative bias to the split-gate. The effective electron concentration and the channel widths were evaluated from magnetoresistance measurements. In the range of channel widths 500 - 100 nm, at temperatures 1-10 K we clearly observe the logarithmic temperature dependences of the conductance. These dependences are adequately explained by effects of electron-electron interaction in weakly-disordered quasi-one dimensional (with respect to the interaction) Fermi liquid [1]. When the width further decreases, the logarithmic dependences change to power-law dependences, which are typical for Luttinger liquid. This crossover takes place when the channel width corresponds to 2-3 one-dimensional subbands. [1] Sergeev et.al., Phys. Rev. B. 69, 075310 (2004).

Bell, Matthew; Sergeev, Andrei; Bird, Jonathan; Mitin, Vladimir; Verevkin, Aleksandr

2009-03-01

45

Charge fractionalization in nonchiral Luttinger systems  

NASA Astrophysics Data System (ADS)

One-dimensional metals, such as quantum wires or carbon nanotubes, can carry charge in arbitrary units, smaller or larger than a single electron charge. However, according to Luttinger theory, which describes the low-energy excitations of such systems, when a single electron is injected by tunneling into the middle of such a wire, it will tend to break up into separate charge pulses, moving in opposite directions, which carry definite fractions f and (1-f) of the electron charge, determined by a parameter g that measures the strength of charge interactions in the wire. (The injected electron will also produce a spin excitation, which will travel at a different velocity than the charge excitations.) Observing charge fractionalization physics in an experiment is a challenge in those (nonchiral) low-dimensional systems which are adiabatically coupled to Fermi liquid leads. We theoretically discuss a first important step towards the observation of charge fractionalization in quantum wires based on momentum-resolved tunneling and multi-terminal geometries, and explain the recent experimental results of Steinberg et al. [H. Steinberg, G. Barak, A. Yacoby, L.N. Pfeiffer, K.W. West, B.I. Halperin, K. Le Hur, Nature Physics 4 (2008) 116].

Le Hur, Karyn; Halperin, Bertrand I.; Yacoby, Amir

2008-12-01

46

Charge fractionalization in nonchiral Luttinger systems  

SciTech Connect

One-dimensional metals, such as quantum wires or carbon nanotubes, can carry charge in arbitrary units, smaller or larger than a single electron charge. However, according to Luttinger theory, which describes the low-energy excitations of such systems, when a single electron is injected by tunneling into the middle of such a wire, it will tend to break up into separate charge pulses, moving in opposite directions, which carry definite fractions f and (1-f) of the electron charge, determined by a parameter g that measures the strength of charge interactions in the wire. (The injected electron will also produce a spin excitation, which will travel at a different velocity than the charge excitations.) Observing charge fractionalization physics in an experiment is a challenge in those (nonchiral) low-dimensional systems which are adiabatically coupled to Fermi liquid leads. We theoretically discuss a first important step towards the observation of charge fractionalization in quantum wires based on momentum-resolved tunneling and multi-terminal geometries, and explain the recent experimental results of Steinberg et al. [H. Steinberg, G. Barak, A. Yacoby, L.N. Pfeiffer, K.W. West, B.I. Halperin, K. Le Hur, Nature Physics 4 (2008) 116].

Le Hur, Karyn [Department of Physics, Yale University, P.O. Box 208220, New Haven, CT 06520 (United States)], E-mail: karyn.lehur@yale.edu; Halperin, Bertrand I.; Yacoby, Amir [Department of Physics, Harvard University, Cambridge, MA 02138 (United States)

2008-12-15

47

Laterally excited flexible tanks with nonuniform density liquid  

Microsoft Academic Search

A study of the dynamic responses of flexible tanks containing nonuniform liquid under horizontal base excitations is presented. The system considered is an upright, circular cylindrical tank filled with an incompressible and inviscid liquid in which the density increases with the liquid depth. Only the impulsive components of response are considered in this study since the convective components can be

Yu Tang

1996-01-01

48

Luttinger surgery and Kodaira dimension  

E-print Network

In this note we show that the Lagrangian Luttinger surgery preserves the symplectic Kodaira dimension. Some constraints on Lagrangian tori in symplectic four manifolds with non-positive Kodaira dimension are also derived.

Ho, Chung-I

2011-01-01

49

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

SciTech Connect

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

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

1984-01-01

50

Linear response of a viscous liquid to translational excitation  

Microsoft Academic Search

Forced oscillations of a viscous liquid with a free liquid surface in a circular cylindrical container have been treated\\u000a by observing various boundary conditions. The response of the velocity distribution, the free surface elevation and response\\u000a force of the liquid due to translational excitation of the tank have been determined. Three cases have been treated and compared\\u000a with each other.

H. F. Bauer; W. Eidel

2002-01-01

51

Gravity jitter excited cryogenic liquid slosh waves in microgravity environment  

NASA Astrophysics Data System (ADS)

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

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

52

Elementary excitation and energy landscape in simple liquids  

NASA Astrophysics Data System (ADS)

The nature of excitations in liquids has been a subject of debate for a long time. In liquids, phonons are extremely short-lived and marginalized. Instead, recent research results indicate that local topological or configurational excitations (anankeons) are the elementary excitations in high temperature metallic liquids. Local topological excitations are those which locally alter the atomic connectivity network by cutting or forming atomic bonds, and are directly tied to the atomistic origin of viscosity in the liquid. The local potential energy landscape (PEL) of anankeons represents the probability weighted projection of the global PEL to a single atom. The original PEL is an insightful concept, but is highly multi-dimensional and difficult to characterize or even to visualize. A description in terms of the local PEL for anankeons appears to offer a simpler and more effective approach toward this complex problem. At the base of these advances, is the recognition that atomic discreteness and the topology of atomic connectivity are the most crucial features of the structure in liquids, which current nonlinear continuum theories cannot fully capture. These discoveries could open the way to the explanation of various complex phenomena in liquids, such as atomic transport, fragility, and the glass transition, in terms of these excitations.

Egami, T.

2014-06-01

53

TomonagaLuttinger physics in electronic quantum circuits  

PubMed Central

In one-dimensional conductors, interactions result in correlated electronic systems. At low energy, a hallmark signature of the so-called TomonagaLuttinger 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 TomonagaLuttinger 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 TomonagaLuttinger conductance curve, we demonstrate experimentally the predicted mapping between dynamical Coulomb blockade and the transport across a TomonagaLuttinger liquid with an impurity. PMID:23653214

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

2013-01-01

54

Minimal excitation states of electrons in one-dimensional wires.  

PubMed

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

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

2006-09-15

55

The liquid to vapor phase transition in excited nuclei  

SciTech Connect

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.

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

56

Luttinger-like parameter calculations  

SciTech Connect

We have calculated the Luttinger-like parameters, used in the 8{times}8 Hamiltonian describing both conduction and valence bands, via a second-order perturbation theory that allows one to make the Lowdin renormalization valid for a set of nondegenerate energy levels. We show that the formulas given in the paper by Pidgeon and Brown [Phys. Rev. >146, 575 (1966)] are the correct ones, contrary to what is claimed in recent papers. This leads to strong discrepancies when the spin-orbit splitting is not much smaller than the band gap. For example, the ratio between the Luttinger-like parameters {tilde {gamma}}{sub 1}, calculated in the two cases, is of the order of 1.5 in GaAs, 3 in InAs, and 16 in InSb. The accuracy of the equations used by Pidgeon and Brown is also discussed.

Boujdaria, Kais; Ridene, Said; Fishman, Guy

2001-06-15

57

Topological Approach to Luttinger's Theorem and the Fermi Surface of a Kondo Lattice  

Microsoft Academic Search

A nonperturbative proof of Luttinger's theorem, based on a topological argument, is given for Fermi liquids in arbitrary dimensions. Application to the Kondo lattice shows that even completely localized spins contribute to the Fermi sea volume as electrons, whenever the system can be described as a Fermi liquid.

Masaki Oshikawa

2000-01-01

58

Decay of fermionic quasiparticles in one-dimensional quantum liquids.  

PubMed

The low-energy properties of one-dimensional quantum liquids are commonly described in terms of the Tomonaga-Luttinger liquid theory, in which the elementary excitations are free bosons. To this approximation, the theory can be alternatively recast in terms of free fermions. In both approaches, small perturbations give rise to finite lifetimes of excitations. We evaluate the decay rate of fermionic excitations and show that it scales as the eighth power of energy, in contrast to the much faster decay of bosonic excitations. Our results can be tested experimentally by measuring the broadening of power-law features in the density structure factor or spectral functions. PMID:24483750

Matveev, K A; Furusaki, A

2013-12-20

59

Dissociative ionization of liquid water induced by vibrational overtone excitation  

SciTech Connect

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.

Natzle, W.C.

1983-03-01

60

Theoretical studies of elementary excitations in liquid 4He  

NASA Astrophysics Data System (ADS)

Elementary excitations of liquid 4He have been studied in the past with either perturbation theory in the basis of Feynman phonon states, or with variational theory using Feynman-Cohen (FC) wave functions. We develop perturbation theory in the basis of FC phonon states. Such a theory appears to have much better convergence. The second-order corrections to the FC spectrum are calculated, and these improve the agreement with experiment very significantly. We also calculate the strength Z(k) of the collective mode. The second-order corrections to the Z(k) of FC phonons also improve the agreement with experiment. Calculations are carried out at pressures of 0, 10, and 24 atm using the variational, Green's-function Monte Carlo and experimental pair distribution functions. Corrections to the Kirkwood superposition approximation for the three- and four-particle distribution functions are calculated with the variational ground-state wave functions containing pair and triplet correlations.

Manousakis, E.; Pandharipande, V. R.

1984-11-01

61

Simple glass-forming liquids: their definition, fragilities, and landscape excitation profiles  

Microsoft Academic Search

The `excitation profile' of a liquid is a measure of the rate per kelvin at which the liquid is driven by entropy generation to the top of its potential energy landscape. We argue that it determines the liquid fragility, and hence controls the canonical features of viscous liquid phenomenology. We seek to prove this using studies of simple glass formers.

C. A. Angell; B. E. Richards; V. Velikov

1999-01-01

62

Edge physics of the quantum spin Hall insulator from a quantum dot excited by optical absorption.  

PubMed

The gapless edge modes of the quantum spin Hall insulator form a helical liquid in which the direction of motion along the edge is determined by the spin orientation of the electrons. In order to probe the Luttinger liquid physics of these edge states and their interaction with a magnetic (Kondo) impurity, we consider a setup where the helical liquid is tunnel coupled to a semiconductor quantum dot that is excited by optical absorption, thereby inducing an effective quantum quench of the tunneling. At low energy, the absorption spectrum is dominated by a power-law singularity. The corresponding exponent is directly related to the interaction strength (Luttinger parameter) and can be computed exactly using boundary conformal field theory thanks to the unique nature of the quantum spin Hall edge. PMID:24766003

Vasseur, Romain; Moore, Joel E

2014-04-11

63

Acoustic excitation of liquid fuel droplets and coaxial jets  

NASA Astrophysics Data System (ADS)

This experimental study focuses on two important problems relevant to acoustic coupling with condensed phase transport processes, with special relevance to liquid rocket engine and airbreathing engine combustion instabilities. The first part of this dissertation describes droplet combustion characteristics of various fuels during exposure to external acoustical perturbations. Methanol, ethanol, a liquid synthetic fuel derived from coal gasification via the Fischer-Tropsch process, and a blend of aviation fuel and the synthetic fuel are used. During acoustic excitation, the droplet is situated at or near a pressure node condition, where the droplet experiences the largest velocity perturbations, and at or near a pressure antinode condition, where the droplet is exposed to minimal velocity fluctuations. For unforced conditions, the values of the droplet burning rate constant K of the different fuels are consistent with data in the literature. The location of the droplet with respect to a pressure node or antinode also has a measurable effect on droplet burning rates, which are different for different fuels and in some cases are as high as 28% above the unforced burning rate value. Estimates of flame extinction due to acoustic forcing for different fuels are also obtained. The second part of this work consists of an experimental study on coaxial jet behavior under non-reactive, cryogenic conditions, with direct applications to flow mixing and unstable behavior characterization in liquid rocket engines. These experiments, conducted with nitrogen, span a range of outer to inner jet momentum flux ratios from 0.013 to 23, and explore subcritical, nearcritical and supercritical pressure conditions, with and without acoustic excitation, for two injector geometries. Acoustic forcing at 3 kHz is utilized to maximize the pressure fluctuations within the chamber acting on the jet, reaching maximum values of 4% of the mean chamber pressure. The effect of the magnitude and phase of the acoustic field generated within the chamber on the dark core length and the inner jet spreading angles is presented and the stability of coaxial flows in the current flow regime is discussed with respect to evidence for convective and absolute jet instabilities under different operating conditions.

Rodriguez, Juan Ignacio

64

Polarized neutron scattering investigation of excitations at low momentum transfer in liquid Ga: The mystery continues  

E-print Network

Polarized neutron scattering investigation of excitations at low momentum transfer in liquid Ga: Liquid metals; Scattering; Excitations; Sum-rule violation New polarized neutron scattering experiments in the literature. Our polarized neutron scattering experiments show that this increased cross-section cannot

Montfrooij, Wouter

65

Anomalous superconductivity in coupled Luttinger liquids  

E-print Network

an anomalous non­BCS self­consistence equation. If the extremal point is a global minimum the model a is the chain index and H i , i = a; b is given by H i = H 0 i + V i H 0 i = 1 L X k;oe;! [!k \\Gamma pF ]a + k;!;oe;i a \\Gamma k;!;oe;i V i = \\Gamma?? 1 L 4 X k1 ;k2 ;k3 ;k4 X !;oe;oe 0 a + k1;!;oe;i a \\Gamma k2 ;!;oe;i a + k3

Roma "La Sapienza", Università di

66

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

NASA Technical Reports Server (NTRS)

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.

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

1992-01-01

67

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

NASA Astrophysics Data System (ADS)

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.

Hou, Ling; Li, Fangcheng; Wu, Chunliang

2012-09-01

68

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

NASA Astrophysics Data System (ADS)

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.

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

69

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

NASA Astrophysics Data System (ADS)

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.

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

1992-08-01

70

Electromechanical response to white noise excitation in a ferroelectric liquid crystal  

E-print Network

783 Electromechanical response to white noise excitation in a ferroelectric liquid crystal G. Por possible to use white noise excitation as an input signal. By measuring the time response of the system to the white noise, one can estimate the transfer function (by using for example Fast Fourier Transformation

Boyer, Edmond

71

Investigation of Nanostructure in Room Temperature Ionic Liquids using Electronic Excitation Transfer  

E-print Network

for this phenomenon has be seen in fluorescence21,22 and optical Kerr effect studies.23 This partitioning appearsInvestigation of Nanostructure in Room Temperature Ionic Liquids using Electronic Excitation temperature ionic liquid (RTIL) 1-methyl-3- octylimidazolium chloride using time dependent fluorescence

Fayer, Michael D.

72

Quantum fragile matter: mechanical excitations of a Reggeon ion chain  

E-print Network

This paper proposes to study quantum fragile materials with small linear elasticity and a strong response to zero-point fluctuations. As a first model, we consider a non-unitary (but PT-symmetric) massive quantum chain with a Reggeon-type cubic nonlinearity. At the critical point, the chain supports neither the ordinary quantum phonons of a Luttinger liquid, nor the supersonic solitons that arise in classical fragile critical points in the absence of fluctuations. Quantum fluctuations, approximately captured within a one-loop renormalization group, give rise to mechanical excitations with a nonlinear dispersion relation and dissipative spectral behavior. Models of similar complexity should be realizable with trapped ions.

Strack, Philipp

2013-01-01

73

Liquid settlement, resettlement, slosh wave excitation and geyser motion during during reorientation in microgravity  

NASA Astrophysics Data System (ADS)

A key objective of 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. Resettlement or reorientation of liquid propellant can be accomplished by providing the optimal impulsive acceleration to the spacecraft such that the propellant is reoriented over the tank outlet. Characteristics of slosh waves of various frequencies excited by the resettling flow field are discussed. Slosh wave excitations shift the fluid mass distribution in the container which impose time dependent variations in spacecraft moment of inertia. This information is important for spacecraft control during the course of liquid reorientation.

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

1993-07-01

74

A Luttinger Hamiltonian is not enough  

NASA Astrophysics Data System (ADS)

In the study of spintronics, it is important to understand carrier transport in multiple energy bands, such as in the conduction or valence bands in semiconductors. Such bands are often described by effective Luttinger Hamiltonians, derived from k.p perturbation and symmetry considerations. A closely related case is the Pauli Hamiltonian, which suppose to give an effective description for the upper Dirac bands in the non-relativistic limits. Here we show that such an effective Hamiltonian alone is not really sufficient. Various Berry phase type corrections must be supplemented to give proper description of electron charge and spin dynamics.

Chang, M. C.; Chuu, C. P.; Niu, Q.

2006-03-01

75

Topological excitations and the dynamic structure factor of spin liquids on the kagome lattice  

NASA Astrophysics Data System (ADS)

Recent neutron scattering experiments on the spin-1/2 kagome lattice antiferromagnet ZnCu3(OH)6Cl2 (Herbertsmithite) provide the first evidence of fractionalized excitations in a quantum spin liquid state in two spatial dimensions. In contrast to existing theoretical models of both gapped and gapless spin liquids, which give rise to sharp dispersing features in the dynamic structure factor, the measured dynamic structure factor reveals an excitation continuum that is remarkably flat as a function of frequency. Here we show that many experimentally observed features can be explained by the presence of topological vison excitations in a Z2 spin liquid. These visons form flat bands on the kagome lattice, and thus act as a momentum sink for spin-carrying excitations that are probed by neutron scattering. We compute the dynamic structure factor for two different Z2 spin liquids and find that our results for one of them are in qualitative agreement with the neutron scattering experiments above a very low energy cutoff, below which the structure factor is probably dominated by impurities.

Punk, Matthias; Chowdhury, Debanjan; Sachdev, Subir

2014-04-01

76

On the Kohn-Luttinger conundrum  

SciTech Connect

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.

Hirata, So [Department of Chemistry, University of Illinois at Urbana-Champaign, 600 South Mathews Avenue, Urbana, Illinois 61801 (United States); CREST, Japan Science and Technology Agency, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012 (Japan); He Xiao [Department of Chemistry, University of Illinois at Urbana-Champaign, 600 South Mathews Avenue, Urbana, Illinois 61801 (United States)

2013-05-28

77

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

SciTech Connect

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.}

Clements, B.E. [Department of Physics, Texas A& M University, College Station, Texas 77843 (United States)] [Department of Physics, Texas A& M University, College Station, Texas 77843 (United States); [Institute Laue Langevin, 38042 Grenoble Cedex (France); Godfrin, H. [Centre de Recherches sur les Tres Basses Temperatures, CNRS, Boite Postale 166X, 38042 Grenoble (France)] [Centre de Recherches sur les Tres Basses Temperatures, CNRS, Boite Postale 166X, 38042 Grenoble (France); Krotscheck, E. [Department of Physics, Texas A& M University, College Station, Texas 77843 (United States)] [Department of Physics, Texas A& M University, College Station, Texas 77843 (United States); [Institut fuer Theoretische Physik, Johannes Kepler Universitaet, A 4040 Linz (Austria); Lauter, H.J. [Institute Laue Langevin, 38042 Grenoble Cedex (France)] [Institute Laue Langevin, 38042 Grenoble Cedex (France); Leiderer, P. [Fachbereich Physik, Universitaet Konstanz, Konstanz (Germany)] [Fachbereich Physik, Universitaet Konstanz, Konstanz (Germany); Passiouk, V. [Institute Laue Langevin, 38042 Grenoble Cedex (France)] [Institute Laue Langevin, 38042 Grenoble Cedex (France); [Fachbereich Physik, Universitaet Konstanz, Konstanz (Germany); Tymczak, C.J. [Department of Physics, Texas A& M University, College Station, Texas 77843 (United States)] [Department of Physics, Texas A& M University, College Station, Texas 77843 (United States)

1996-05-01

78

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

NASA Astrophysics Data System (ADS)

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.

Penedo, M.; Raman, A.; Hormeo, S.; Fernndez-Martnez, I.; Luna, M.; Briones, F.

2014-10-01

79

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

NASA Astrophysics Data System (ADS)

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

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

80

Disclination Classes, Fractional Excitations, and the Melting of Quantum Liquid Crystals  

NASA Astrophysics Data System (ADS)

We consider how fractional excitations bound to a dislocation evolve as the dislocation is separated into a pair of disclinations. We show that some dislocation-bound excitations (such as Majorana modes and half-quantum vortices) are possible only if the elementary dislocation consists of two inequivalent disclinations, as is the case for stripes or square lattices but not for triangular lattices. The existence of multiple inequivalent disclination classes governs the two-dimensional melting of quantum liquid crystals (i.e., nematics and hexatics), determining whether superfluidity and orientational order can simultaneously vanish at a continuous transition.

Gopalakrishnan, Sarang; Teo, Jeffrey C. Y.; Hughes, Taylor L.

2013-07-01

81

Coherent control of the molecular dynamics in a liquid by femtosecond four-pulse excitation  

NASA Astrophysics Data System (ADS)

The laser non-resonant excitation based on the (2? ?2) sequence of the two pairs of the pump pulses with orthogonal linear polarizations is proposed and theoretically considered for the control of the vibrational responses without or with the low amplitude of the rotational responses in a liquid. As an example, we model the optical molecular responses resulting in the optical Kerr effect transients in ortho-dichlorobenzene. Theoretical analysis shows the high efficiency of the (2? ?2) excitation scenarios for the various manipulations of the molecular responses.

Nikiforov, V. G.; Lobkov, V. S.; Samartsev, V. V.; Saiko, A. P.

2015-01-01

82

Luttinger Model in Dimensions d > 1  

NASA Astrophysics Data System (ADS)

In the present work the Luttinger model is formally extended to d > 1 dimensions. For purposes of comparison with the original model only short-range forces linking the fermions have been considered (as in the Hubbard model). The Fermi sea is decomposed into sectors labeled by wave-vectors q, each containing a set of orthogonal, independent normal modes. Operators that create or destroy normal modes within any given sector are shown to commute with those originating in other sectors. Because the Hamiltonian within each sector is a quadratic form in these normal modes it can be diagonalized in a multitude of ways. One convenient method consists of mapping it onto a model first introduced elsewhere in this volume, the d = 1 expanded Luttinger model. It too can be diagonalized, albeit not so trivially as the original, but by constructing and then diagonalizing a boson string. A product of eigenstates -- one from each sector -- is used to construct an exact eigenstate of the full many-body problem if the algebra connecting all the normal modes is Abelian. However, some form of non-Abelian algebra governs the normal modes in the presence of any sort of long-range order (LRO), whether ferromagnetic, antiferromagnetic or superconducting. (Note that the Mermin-Wagner theorem does preclude spontaneous LRO in dimensions d ? 2). Although it is also important to understand the nature of dynamical exchange corrections to arbitrary-range interactions -- including the physically important Coulomb interaction -- a detailed derivation, together with such other conundrum as the calculation of one-fermion distribution functions from "first principles," all are topics relegated to future publications.

Mattis, Daniel C.

2014-10-01

83

High-Resolution Frequency-Modulation Atomic Force Microscopy in Liquids Using Electrostatic Excitation Method  

NASA Astrophysics Data System (ADS)

We developed a novel method to drive the cantilever oscillation for frequency modulation atomic force microscopy (FM-AFM) in liquid environments using electrostatic excitation. The cantilever with a gold backside coating was vibrated by applying an oscillating bias voltage between the cantilever backside and an optically transparent electrode used as a liquid cell window. The frequency spectrum of the oscillation shows a simple resonance curve without spurious peaks. The method does not require electrical conductivity of samples at all. In fact, both muscovite mica and potassium chloride surfaces in aqueous solutions were successfully imaged on an atomic scale.

Umeda, Ken-ichi; Oyabu, Noriaki; Kobayashi, Kei; Hirata, Yoshiki; Matsushige, Kazumi; Yamada, Hirofumi

2010-06-01

84

Excitation of Capillary Waves in Strongly Absorbing Liquids by a Modulated Laser Beam  

NASA Astrophysics Data System (ADS)

Several mechanisms for the excitation of capillary waves and for the development of the average deformation of a liquid surface under the action of a modulated laser beam are considered. The amplitude of the capillary wave in a strongly absorbing solution of the dye LDS 751 in ethylene glycol is experimentally studied as a function of laser intensity. Consecutive changes in the predominant mechanism of the excitation with increasing laser intensity are observed and described. At low laser intensities the mechanism connected with the creation of a surface tension gradient prevails. This mechanism becomes nonlinear with increasing influence of the convective motion. In addition, pressure pulsations of the convective flow start to contribute significantly to the generation process. The resonances of capillary waves in a cylindrical container are also investigated and used for determining the surface tension and viscosity of the liquid.

Kolomenskii, Alexandre A.; Schuessler, Hans A.

1999-10-01

85

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

Microsoft Academic Search

The authors demonstrate local alignment of nematic liquid crystal through the fabrication of local micrograting structures by curing an ultraviolet curable material via a two-photon excitation laser-lithography process. A local twisted-nematic region was prepared using one rubbed and one fabricated micrograting surface and the resulting cell was observed with a polarizing optical microscope. The polarization optical micrographs of the locally

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

2008-01-01

86

Similarity rules in gravity jitter-related spacecraft liquid propellant slosh waves excitation  

NASA Astrophysics Data System (ADS)

The dynamical behavior of fluids, in particular the effect of surface tension on partially filled rotating fluids in a full-scale prototype Gravity Probe-B Spacecraft propellant tank and various 10 percent subscale containers with identical values of similarity parameters such as Bond number, dynamical capillary number, rotational Reynolds number, and Weber number, as well as imposed gravity jitters have been investigated. It is shown that the Bond number can be used to simulate the wave characteristics of slosh wave excitation, whereas the Weber number can be used to simulate the wave amplitude of slosh-mode excitation. It is shown that a dynamical capillary number can be used to simulate the induced perturbation of the fluid stress distribution exerted on the wall. This distribution is governed by the interaction between surface tension (slosh-wave excitation along the liquid-vapor interface) and viscous (fluid stress exerted on the wall) forces.

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

1992-07-01

87

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

PubMed Central

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

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

2013-01-01

88

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

NASA Astrophysics Data System (ADS)

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, Poincar 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.

Ikeda, Takashi; Murakami, Shin

89

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

SciTech Connect

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.

Chang, Mei-Chu; Tseng, Yu-Ping; I, Lin [Department of Physics and Center for Complex Systems, National Central University, Jhongli, Taiwan 32001 (China)

2011-03-15

90

Edge excitations and topological order in a rotating Bose gas  

SciTech Connect

The edge excitations and related topological orders of correlated states of a fast rotating Bose gas are studied. Using exact diagonalization of small systems, we compute the energies and number of edge excitations, as well as the boson occupancy near the edge for various states. The chiral Luttinger-liquid theory of Wen is found to be a good description of the edges of the bosonic Laughlin and other states identified as members of the principal Jain sequence for bosons. However, we find that in a harmonic trap the edge of the state identified as the Moore-Read (Pfaffian) state shows a number of anomalies. An experimental way of detecting these correlated states is also discussed.

Cazalilla, M.A. [Donostia International Physics Center (DIPC), Manuel de Lardizabal 4, 20018-Donostia (Spain); Barberan, N. [Dept. ECM, Facultat de Fisica, Universitat de Barcelona, Diagonal 647, 08028-Barcelona (Spain); Cooper, N.R. [Cavendish Laboratory, Madingley Road, Cambridge, CB3 0HE (United Kingdom)

2005-03-15

91

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

NASA Astrophysics Data System (ADS)

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.

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

92

Biological membrane modeling with a liquid/liquid interface. Probing mobility and environment with total internal reflection excited fluorescence.  

PubMed Central

Total internal reflection of exciting light, in combination with fluorescence intensity and polarization measurements, was used to selectively study fluorescent compounds adsorbed to the interface region between two immiscible liquids. A fluorometer was constructed which provided excitation at variable angles of incidence and allowed sensitive detection of polarized fluorescence emitted from the interface. The compound 4,4'-bis-1-phenylamino-8-naphthalenesulfonate (bis-ANS) was examined at a decalin/water interface and was found to possess remarkable affinity for the interface region with the bulk of the adsorbed molecule residing in the decalin phase. The adsorbed fluorophore displayed an apparent hindered rotation in the plane of the interface with a rotational diffusion coefficient 3- to 12-fold lower than that expected for bis-ANS in solution. While other dyes examined were not found to be significantly surface active, the addition of cationic surfactant sufficed to induce adsorption of the anionic fluorophore 1-aminonaphthalene-3,6,8-trisulfonic acid. This fluoropore was found to reside in an aqueous environment when bound to the interface, and it also exhibited hindered rotation in the plane of the interface. As the concentrations of the dyes were increased, both adsorbed dyes exhibited polarization reductions consistent with excitation energy transfer. Adsorption of bis-ANS was reversed by addition of bovine serum albumin. The membrane protein cytochrome b5 was found not to bind at the decalin/water interface, indicating that interaction with lipid is required for its adherence to biological membranes. PMID:3651556

Morrison, L E; Weber, G

1987-01-01

93

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

E-print Network

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

Ettore Segreto

2014-11-17

94

Inelastic x-ray scattering as a probe of electronic excitations. Solid and liquid metals  

SciTech Connect

Use of inelastic x-ray scattering to study excitations in condensed matter systems is discussed with emphasis on complementarity with inelastic neutron scattering. In particular, studies of electronic excitations in simple metals are detailed. A long standing controversy on the role of crystalline long range order on electron dynamics at intermediate momentum transfers is resolved by comparison of response functions obtained in liquid an solid phase of Li, Na, and Al. They show that the overall shape of the response function is unchanged on melting, implying that it is not determined by the long range order of the ion cores. Conversely, orientationally independent fine structure disappears on melting and therefore must be attributed to band structure-induced transitions, not many-body effects as had previously been argued. At small q, the plasmon lifetime and dispersion remain unchanged on melting. Other experiments are also briefly reviewed.

Hill, J.P.

1996-12-31

95

Bose-Einstein Condensation in the Luttinger-Sy Model  

E-print Network

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

Olivier Lenoble; Valentin Zagrebnov

2006-04-27

96

Laser-excited shear waves in solid and liquid two-dimensional dusty plasmas  

SciTech Connect

The propagation of transverse waves in a two-dimensional particle suspension in a plasma is studied in the solid and liquid phase. The different states of the suspension are realized by raising the kinetic temperature of the dust particles with a new laser method. An additional laser beam is used to excite shear waves and the wave is observed by videomicroscopy in terms of the individual velocities of the dust particles. For recovering the spatial wave patterns the method of singular value decomposition is applied and compared with the method of spatial Fourier analysis of complex wave numbers. In the solid phase, weakly damped waves are found which follow the expected dispersion relation. In the liquid phase the existence of strongly damped waves is demonstrated. The real part of the wave number is in overall agreement with the predictions of the Quasi Localized Charge Approximation model for a two-dimensional system. The damping of the waves is discussed.

Piel, A.; Nosenko, V.; Goree, J. [IEAP, Christian-Albrechts-Universitaet, D-24098 Kiel (Germany); Department of Physics and Astronomy, University of Iowa, Iowa City, Iowa (United States)

2006-04-15

97

Wave packet dynamics in hole Luttinger systems  

SciTech Connect

For hole systems with an effective spin 3/2 we analyzed analytically and numerically the evolution of wave packets with the different initial polarizations. The dynamics of such systems is determined by the 4x4 Luttinger Hamiltonian. We work in the space of arbitrary superposition of light- and heavy-hole states of the ''one-particle system.'' For strong anisotropic packets in three-dimensional semiconductors we obtained the analytical solution for the components of wave function and analyzed the space-time dependence of probability densities as well as angular momentum densities. Depending on the value of the parameter a=k{sub 0}d (k{sub 0} is the average momentum vector and d is the packet width) two scenarios of evolution are realized. For a>>1 the initial wave packet splits into two parts and the coordinates of packet center experience the transient oscillations or Zitterbewegung (ZB) as for other two-band systems. In the case when a<<1 the distribution of probability density at t>0 remains almost cylindrically symmetric and the ripples arise at the circumference of wave packet. The ZB in this case is absent. We evaluated and visualized for different values of parameter a the space-time dependence of angular momentum densities, which have the multipole structure. It was shown that the average momentum components can precess in the absence of external or effective magnetic fields due to the interference of the light- and heavy-hole states. For localized initial states this precession has a transient character.

Demikhovskii, V. Ya.; Maksimova, G. M.; Frolova, E. V. [Nizhny Novgorod State University, Gagarin Avenue, 23, Nizhny Novgorod 603950 (Russian Federation)

2010-03-15

98

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

PubMed

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

Kiracofe, Daniel; Raman, Arvind

2011-12-01

99

Excite  

NSDL National Science Digital Library

Hot on the heels of AltaVista's Raging Search (see the May 5, 2000 Scout Report) comes another returned and (somewhat) slimmed-down search engine that focuses on relevant results. Like Raging Search, Excite's new Precision Search uses Google-style link analysis technology ("Deep Analysis") to help identify the most useful sites. Test queries produced consistently relevant results among the top few returns, though an indication of the number of total returns would be helpful, with two banner ads and (in some but not all cases) a Quick Results box on the left that could be quite handy for consumer-related searching. For instance, a search for "Plymouth" yielded links to research and comparisons, blue book values, financing, and service and repair information in the Quick Results box. I was also pleased to see that clicking on one of the other search categories (category, news, photo, audio/video) instantly produces returns for the original query, though the photo databases available seem somewhat limited compared to, say, AltaVista. While users searching for "official" sites will still do best at Google, those who also search for additional resources such as news, photos, and audio/video content may wish to give Excite Precision a run-through.

100

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)

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 110-16 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.

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

2015-03-01

101

Fragility, Stokes-Einstein violation, and correlated local excitations in a coarse-grained model of an ionic liquid  

E-print Network

Dynamics of a coarse-grained model for the room-temperature ionic liquid, 1-ethyl-3-methylimidazolium hexafluorophosphate, couched in the united-atom site representation are studied via molecular dynamics simulations. The dynamically heterogeneous behavior of the model resembles that of fragile supercooled liquids. At or close to room temperature, the model ionic liquid exhibits slow dynamics, characterized by nonexponential structural relaxation and subdiffusive behavior. The structural relaxation time, closely related to the viscosity, shows a super-Arrhenius behavior. Local excitations, defined as displacement of an ion exceeding a threshold distance, are found to be mainly responsible for structural relaxation in the alternating structure of cations and anions. As the temperature is lowered, excitations become progressively more correlated. This results in the decoupling of exchange and persistence times, reflecting a violation of the Stokes-Einstein relation.

Daun Jeong; M. Y. Choi; Hyung. J. Kim; YounJoon Jung

2010-02-03

102

Fragility, Stokes-Einstein violation, and correlated local excitations in a coarse-grained model of an ionic liquid  

E-print Network

Dynamics of a coarse-grained model for the room-temperature ionic liquid, 1-ethyl-3-methylimidazolium hexafluorophosphate, couched in the united-atom site representation are studied via molecular dynamics simulations. The dynamically heterogeneous behavior of the model resembles that of fragile supercooled liquids. At or close to room temperature, the model ionic liquid exhibits slow dynamics, characterized by nonexponential structural relaxation and subdiffusive behavior. The structural relaxation time, closely related to the viscosity, shows a super-Arrhenius behavior. Local excitations, defined as displacement of an ion exceeding a threshold distance, are found to be mainly responsible for structural relaxation in the alternating structure of cations and anions. As the temperature is lowered, excitations become progressively more correlated. This results in the decoupling of exchange and persistence times, reflecting a violation of the Stokes-Einstein relation.

Jeong, Daun; Kim, Hyung J; Jung, YounJoon; 10.1039/B921725H

2010-01-01

103

The Kohn-Luttinger superconductivity in idealized doped graphene  

NASA Astrophysics Data System (ADS)

Idealized graphene monolayer is considered neglecting the van der Waals potential of the substrate and the role of the nonmagnetic impurities. The effect of the long-range Coulomb repulsion in an ensemble of Dirac fermions on the formation of the superconducting pairing in a monolayer is studied in the framework of the Kohn-Luttinger mechanism. The electronic structure of graphene is described in the strong coupling Wannier representation on the hexagonal lattice. We use the Shubin-Vonsowsky model which takes into account the intra- and intersite Coulomb repulsions of electrons. The Cooper instability is established by solving the Bethe-Salpeter integral equation, in which the role of the effective interaction is played by the renormalized scattering amplitude. The renormalized amplitude contains the Kohn-Luttinger polarization contributions up to and including the second-order terms in the Coulomb repulsion. We construct the superconductive phase diagram for the idealized graphene monolayer and show that the Kohn-Luttinger renormalizations and the intersite Coulomb repulsion significantly affect the interplay between the superconducting phases with f-, d+id-, and p+ip-wave symmetries of the order parameter.

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

2014-06-01

104

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

NASA Astrophysics Data System (ADS)

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.

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

2014-01-01

105

Intra-Landau-level excitations of the two-dimensional electron-hole liquid.  

PubMed

The intra-Landau-level excitations of the two-dimensional electron-hole liquid are characterized by two branches of the energy spectrum. The acoustical plasmon branch with in-phase oscillations of electrons and holes has a linear dispersion law in the range of small wavevectors, with a velocity which does not depend on the magnetic field strength, and monotonically increases with saturation at higher values of the wavevectors. The optical plasmon branch with oscillations of electrons and holes in opposite phases has a quadratic dependence in the range of long wavelength, a weak roton-type behaviour at the intermediary values of the wavevectors and monotonically increases with saturation similar to the case of the acoustical branch. The influence of the supplementary in-plane electric field leads to the drift of the charged particles in the crossed electric and magnetic fields and to the energy spectrum as in the reference frame, where the e-h system is moving with the drift velocity. A perturbation theory using the Green function method is developed on the basis of a small parameter v(2)(1-v(2)), where v(2) is the filling factor and (1-v(2)) displays the phase space filling effect. PMID:21825595

Moskalenko, S A; Liberman, M A; Dumanov, E V; Stefan, A G; Shmiglyuk, M I

2009-06-10

106

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

SciTech Connect

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.

Nishida, Shuhei; Kobayashi, Dai; Sakurada, Takeo; Nakazawa, Tomonori; Hoshi, Yasuo; Kawakatsu, Hideki [Institute of Industrial Science, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8505 (Japan)

2008-12-15

107

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

NASA Astrophysics Data System (ADS)

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.

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

2013-12-01

108

Excitation wavelength dependence of excited state intramolecular proton transfer reaction of 4'-N,N-diethylamino-3-hydroxyflavone in room temperature ionic liquids studied by optical Kerr gate fluorescence measurement.  

PubMed

Excited state intramolecular proton transfer reactions (ESIPT) of 4'-N,N-diethylamino-3-hydroxyflavone (DEAHF) in ionic liquids have been studied by steady-state and time-resolved fluorescence measurements at different excitation wavelengths. Steady-state measurements show the relative yield of the tautomeric form to the normal form of DEAHF decreases as excitation wavelength is increased from 380 to 450 nm. The decrease in yield is significant in ionic liquids that have cations with long alkyl chains. The extent of the decrease is correlated with the number of carbon atoms in the alkyl chains. Time-resolved fluorescence measurements using optical Kerr gate spectroscopy show that ESIPT rate has a strong excitation wavelength dependence. There is a large difference between the spectra at a 200 ps delay from different excitation wavelengths in each ionic liquid. The difference is pronounced in ionic liquids having a long alkyl chain. The equilibrium constant in the electronic excited state obtained at a 200 ps delay and the average reaction rate are also correlated with the alkyl chain length. Considering the results of the steady-state fluorescence and time-resolved measurements, the excitation wavelength dependence of ESIPT is explained by state selective excitation due to the difference of the solvation, and the number of alkyl chain carbon atoms is found to be a good indicator of the effect of inhomogeneity for this reaction. PMID:24088033

Suda, Kayo; Terazima, Masahide; Sato, Hirofumi; Kimura, Yoshifumi

2013-10-17

109

Comparison of photothermal and piezoacoustic excitation methods for frequency and phase modulation atomic force microscopy in liquid environments  

NASA Astrophysics Data System (ADS)

In attempting to perform frequency modulation atomic force microscopy (FM-AFM) in liquids, a non-flat phase transfer function in the self-excitation system prevents proper tracking of the cantilever natural frequency. This results in frequency-and-phase modulation atomic force microscopy (FPM-AFM) which lies in between phase modulation atomic force microscopy (PM-AFM) and FM-AFM. We derive the theory necessary to recover the conservative force and damping in such a situation, where standard FM-AFM theory no longer applies. Although our recovery procedure applies to all cantilever excitation methods in principle, its practical implementation may be difficult, or even impossible, if the cantilever is driven piezoacoustically. Specifically, we contrast the piezoacoustic excitation method to the photothermal method in the context of force spectroscopy of hydration structures at the mica-water interface. The results clearly demonstrate that photothermal excitation is superior to piezoacoustic excitation, as it allows for accurate quantitative interpretation of the acquired data.

Labuda, A.; Kobayashi, K.; Kiracofe, D.; Suzuki, K.; Grtter, P. H.; Yamada, H.

2011-06-01

110

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

E-print Network

X-ray study of the liquid potassium surface: Structure and capillary wave excitations Oleg Shpyrko surface of a pure liquid metal with low surface tension. Prior to this study, layering was observed only for metals like Ga, In, and Hg, the surface tensions of which are five- to sevenfold higher than

Grigoriev, Alexei

111

Direct spectroscopic observation of singlet oxygen emission at 1268 nm excited by sensitizing dyes of biological interest in liquid solution  

PubMed Central

The direct observation of dye-photosensitized 1268-nm emission of the 1?g ? 3?g transition of molecular oxygen in liquid solution at room temperature is reported. Singlet oxygen was photosensitized by UV excitation of perfluorobenzophenone in fluorocarbon solvent, by 3,4-benzpyrene and hematoporphyrin in carbon tetrachloride, and by methylene blue in water. Also reported is the development of an extremely sensitive near-infrared spectrophotometer that uses a thermoelectrically cooled lead sulfide detector, optimized optics, and a boxcar integrator as a data processor. PMID:16592729

Khan, A. U.; Kasha, M.

1979-01-01

112

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

NASA Astrophysics Data System (ADS)

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.

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

1992-08-01

113

Magnetic field spectral crossings of Luttinger holes in quantum wells  

NASA Astrophysics Data System (ADS)

We develop an analytic approach to two-dimensional (2D) holes in a magnetic field that allows us to gain insight into physics of measuring the parameters of holes, such as cyclotron resonance, Shubnikov-de Haas effect and spin resonance. We derive hole energies, cyclotron masses, and the g factors in the semiclassical regime analytically, as well as analyze numerical results outside the semiclassical range of parameters, qualitatively explaining the experimentally observed magnetic field dependence of the cyclotron mass. In the semiclassical regime with large Landau level indices, and for size quantization energy much bigger than the cyclotron energy, the cyclotron mass coincides with the in-plane effective mass, calculated in the absence of a magnetic field. The hole g factor in a magnetic field perpendicular to the 2D plane is defined not only by the constant of direct coupling of the angular momentum of the holes to the magnetic field, but also by the Luttinger constants defining the effective masses of holes. We find that the g factor for quasi-2D holes with heavy mass in the [001] growth direction in GaAs quantum well is g =4.05 in the semiclasssical regime. Outside the semiclassical range of parameters, holes behave as a species completely different from electrons. Spectra for size- and magnetic-field-quantized holes are nonequidistant, not fanlike, and exhibit multiple crossings, including crossing in the ground level. We calculate the effect of Dresselhaus terms, which transform some of the crossings into anticrossings, and the effects of the anisotropy of the Luttinger Hamiltonian on the 2D hole spectra. Dresselhaus terms of different symmetries are taken into account, and a regularization procedure is developed for the kz3 Dresselhaus terms. Control of the nonequidistant levels and crossing structure by the magnetic field can be used to control the Landau level mixing in hole systems, and thereby control hole-hole interactions in the magnetic field.

Simion, G. E.; Lyanda-Geller, Y. B.

2014-11-01

114

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

NASA Astrophysics Data System (ADS)

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.

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

1992-01-01

115

Acoustic second harmonic generation from rough surfaces under shear excitation in liquids.  

PubMed

Emission of compressional acoustic waves at the second harmonic frequency (second harmonic generation, SHG) is possible from rough surfaces undergoing oscillatory shear in liquids. This nonlinear response is a consequence of the inertial term in the Navier-Stokes equation. On a corrugated surface, the streamlines of the sheared liquid are not strictly parallel to the surface, leading to variation of pressure along the streamlines and a concomitant Bernoulli pressure. Being quadratic in speed, the Bernoulli pressure contains a static term and a term at the second harmonic frequency, 2omega. Pressure fluctuations at 2omega generate compressional waves. PMID:15518534

Wondraczek, Katrin; Bund, Andreas; Johannsmann, Diethelm

2004-11-01

116

A Simultaneous, Laser-Excited Fluorescence, Photoacoustic, and Two-Photon Photoionization Detector for Liquid Chromatography  

Microsoft Academic Search

A laser-excited windowless flow cell has been developed for simultaneous fluorescence, photoacoustic, and two-photon photoionization detection of aromatic compounds in HPLC eluents. Sensitive three-mode detection of acridine, naphthalene, 7,8-benzoflavone, N-ethylcarbazole, and anthracene in 70\\/30 V\\/V acetonitrile\\/water is demonstrated with conservative detection limits in the nanogram range and below.

E. Voigtman; J. D. Winefordner

1982-01-01

117

A possibility to recognize chirality by an excitable artificial liquid membrane.  

PubMed

Studies were made on oscillations across a liquid membrane consisting of an oil layer, nitrobenzene containing picric acid, between two aqueous layers: a solution of 1.5 M ethanol and 5 mM optically-active cationic detergent, the D- or L-form of N-alpha-methylbenzyl-N,N-dimethylmyristylammonium bromide, on the left and 0.1 M D- or L-form of various ligands, such as glucose, arabinose, alanine, glutamic acid, threonine, leucine, proline, or phenylalanine on the right. This system showed sustained rhythmic oscillations of electrical potential of 200-300 mV with intervals of the order of 1 min. The frequency of oscillations depended on the combination of chiralities of the detergent and ligand. This means that the two forms (D and L) of chiral ligands can be distinguished by differences in the electrical response of the liquid membrane. PMID:3756305

Yoshikawa, K; Omochi, T; Matsubara, Y; Kourai, H

1986-07-01

118

Asymmetric gravity jitter excited slosh waves at a liquid-vapor-solid interface in microgravity  

NASA Astrophysics Data System (ADS)

The dynamical behavior of fluids affected by the asymmetric gravity jitter oscillations is investigated focusing on the surface tension effect on partially filled rotating fluids in a sub-scale gravity probe-B spacecraft propellant dewar tank. Data obtained revealed that the lower frequency gravity jitter imposed on the time-dependent variations of the background gravity direction induced a greater amplitude of oscillations and a stronger degree of asymmetry in liquid-vapor interface geometry than that caused by the higher frequency gravity jitter. It is also found that the greater the components of background gravity in radial and circumferential directions the greater the contribution to driving more toward increasing amplitude and degrees of asymmetry of the liquid-vapor interface profiles, which in turn modify the disturbance of moment of inertia and angular momentum of spacecraft.

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

1992-08-01

119

Minimal-excitation states for electron quantum optics using levitons  

NASA Astrophysics Data System (ADS)

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.

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

2013-10-01

120

A Study of Elementary Excitations of Liquid Helium-4 Using Macro-orbital Microscopic Theory  

E-print Network

Energy of elementary excitations and the anomalous nature of small Q phonons in He-II are studied by using our macro-orbital microscopic theory of a system of interacting bosons (cond-mat/0606571). It is observed that : (i) the experimental E(Q) of He-II not only agrees with our theoretical relation $E(Q) = \\hbar^2Q^2/4mS(Q)$ but also supports an important conclusion of Price that S(0) should have zero value for quantum fluids, and (ii) Feynman's energy of excitations $E(Q)_{Fyn} = \\hbar^2Q^2/2mS(Q)$ equals approximately to $2E(Q)_{exp}$ even at low Q. Three problems with the Feynman's inference that $E(Q)_{Fyn}$ has good agreement with $E(Q)_{exp}$ at low Q are identified. It is argued that the theory can also be used to understand similar spectrum of the BEC state of a dilute gas reported by O'Dell et al.

Yatendra S. Jain

2006-09-18

121

Luttinger-field approach to thermoelectric transport in nanoscale conductors  

NASA Astrophysics Data System (ADS)

Thermoelectric transport in nanoscale conductors is analyzed in terms of the response of the system to a thermomechanical field, first introduced by Luttinger, which couples to the electronic energy density. While in this approach, the temperature remains spatially uniform, we show that a spatially varying thermomechanical field effectively simulates a temperature gradient across the system and allows us to calculate the electric and thermal currents that flow due to the thermomechanical field. In particular, we show that in the long-time limit, the currents thus calculated reduce to those that one obtains from the Landauer-Bttiker formula, suitably generalized to allow for different temperatures in the reservoirs, if the thermomechanical field is applied to prepare the system, and subsequently turned off at t =0. Alternatively, we can drive the system out of equilibrium by switching the thermomechanical field after the initial preparation. We compare these two scenarios, employing a model noninteracting Hamiltonian, in the linear regime, in which they coincide, and in the nonlinear regime, in which they show marked differences. We also show how an operationally defined local effective temperature can be computed within this formalism.

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

2014-09-01

122

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

SciTech Connect

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.

Yang, Yifeng [Los Alamos National Laboratory; Urbano, Ricardo [NHMFL, FL; Nicholas, Curro [UC DAVIS; Pines, David [UC DAVIS

2009-01-01

123

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

SciTech Connect

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.

Peterson, E.S.

1992-08-01

124

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

SciTech Connect

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.

Peterson, E.S.

1992-08-01

125

Contrasting the excited state reaction pathways of phenol and para-methylthiophenol in the gas and liquid phases.  

PubMed

To explore how the solvent influences primary aspects of bond breaking, the gas and solution phase photochemistries of phenol and ofpara-methylthiophenol are directly compared using, respectively, H (Rydberg) atom photofragment translation spectroscopy and femtosecond transient absorption spectroscopy. Approaches are demonstrated that allow explicit comparisons of the nascent product energy disposals and dissociation mechanisms in the two phases. It is found, at least for the case of the weakly perturbing cyclohexane environment, that most aspects of the primary reaction dynamics of the isolated molecule are reproduced in solution. Specifically, in the gas phase, both molecules can undergo fast X-H (X = O, S) bond dissociation upon excitation with short wavelengths (193 < lambda(pump) < 216 nm), following population of the dissociative S2 (1 1(pi sigma*)) state. Product electronic branching, vibrational and translational energy disposals are determined. Photolysis of phenol and para-methylthiophenol in solution at 200 nm results in formation of vibrationally excited radicals on a timescale shorter than 200 fs. Excitation of para-methylthiophenol at 267 nm reaches close to the S1 (1 1(pipi*))/S2 (11(pi sigma*)) conical intersection (CI): ultrafast dissociation is observed in both the isolated and solution systems-again indicating direct dissociation on the S2 potential energy surface. Comparing results for this precursor at different excitation energies, the extent of geminate recombination and the derived H-atom ejection lengths in the condensed phase photolyses are in qualitative agreement with the translational energy release measured in the gas phase studies. Conversely, excitation of phenol at 267 nm prepares the system in its S1 state at an energy well below its S1/S2 CI; the slow O-H bond fission inferred in the gas phase experiments is observed directly in the time-resolved studies in cyclohexane solution via the appearance of phenoxyl radical absorption after -1 ns, with only S1 excited state absorption discernible at earlier delay times. The slow O-H bond fission in solution provides additional evidence for a tunnelling dissociation mechanism, where the H atom tunnels beneath the lower diabats of the S2/S1 CI. Finally, the photodissociation of phenol clusters in solution is considered, where evidence is presented that the O-H dissociation coordinate is impeded in H-bonded dimers. PMID:23230767

Zhang, Yuyuan; Oliver, Thomas A A; Ashfold, Michael N R; Bradforth, Stephen E

2012-01-01

126

Spin-resolved entanglement spectroscopy of critical spin chains and Luttinger liquids  

E-print Network

Quantum critical chains are well described and understood by virtue of conformal field theory. Still the meaning of the real space entanglement spectrum -- the eigenvalues of the reduced density matrix -- of such systems remains in general elusive, even when there is an additional quantum number available such as spin or particle number. In this paper we explore in details the properties and the structure of the reduced density matrix of critical XXZ spin-$\\frac{1}{2}$ chains. We investigate the quantum/thermal correspondence between the reduced density matrix of a $T=0$ pure quantum state and the thermal density matrix of an effective entanglement Hamiltonian. Using large scale DMRG and QMC simulations, we investigate the conformal structure of the spectra, the entanglement Hamiltonian and temperature. We then introduce the notion of spin-resolved entanglement entropies which display interesting scaling features.

Nicolas Laflorencie; Stephan Rachel

2014-07-14

127

Transport properties of a two-lead Luttinger-liquid junction out of equilibrium: Fermionic representation  

NASA Astrophysics Data System (ADS)

The electrical current through an arbitrary junction connecting quantum wires of spinless interacting fermions is calculated in fermionic representation. The wires are adiabatically attached to two reservoirs at chemical potentials differing by the applied voltage bias. The relevant scale-dependent contributions in perturbation theory in the interaction up to infinite order are evaluated and summed up. The result allows one to construct renormalization group equations for the conductance as a function of voltage (or temperature, wire length). There are two fixed points at which the conductance follows a power law in terms of a scaling variable ? , which equals the bias voltage V , if V is the largest energy scale compared to temperature T and inverse wire length L-1, and interpolates between these quantities in the crossover regimes.

Aristov, D. N.; Wlfle, P.

2014-12-01

128

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

PubMed

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 (4)He 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 5mm 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. PMID:23838526

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

129

Excitation-energy dependence of the mechanism for two-photon ionization of liquid H2O and D2O from 8.3to12.4eV  

E-print Network

Transient absorption measurements monitor the geminate recombination kinetics of solvated electrons following two-photonionization of liquid water at several excitation energies in the range from 8.3to12.4eV. Modeling the kinetics of the electron...

Elles, Christopher G.; Jailaubekov, Askat E.; Crowell, Robert A.; Bradforth, Stephen E.

2006-07-28

130

Mobile impurities in ferromagnetic liquids  

NASA Astrophysics Data System (ADS)

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

Kantian, Adrian; Schollwoeck, Ulrich; Giamarchi, Thierry

2011-03-01

131

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

NASA Astrophysics Data System (ADS)

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.

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

2014-10-01

132

The response of a (3)He Fermi liquid droplet to vibronic excitation of an embedded glyoxal molecule.  

PubMed

The zero-phonon line (ZPL) and the sideband in the vibronic spectrum of a single glyoxal molecule inside a (3)He droplet are analyzed within the framework of the Lax formalism. The new theory takes full account of the coupling of the molecule to the single particle-hole (PH) and collective excitations of the doped Fermionic droplet. The effect on the coupling of the wavevector dependence of the effective (3)He mass and the large local density of the first (3)He shell, resulting from the interaction with the chromophore, are also included in the theory. By fitting of a coupling parameter and the phase factor between the PH and collective response functions, the shape and relative intensity of the observed ZPL and its slowly decreasing multiexcitation sideband are well-reproduced. The new theory is consistent with the previous explanation of the surprisingly sharp phonon line superimposed on the sideband in terms of the dense first (3)He shell, which acts as a Helmholtz resonator for the zero sound of the droplet. PMID:24896370

Benedek, Giorgio; Hizhnyakov, Vladimir; Toennies, J Peter

2014-08-21

133

Optimum geometry of tuned liquid column-gas damper for control of offshore jacket platform vibrations under seismic excitation  

NASA Astrophysics Data System (ADS)

In this study, the effectiveness of a tuned liquid column-gas damper, TLCGD, on the suppression of seismicinduced vibrations of steel jacket platforms is evaluated. TLCGD is an interesting choice in the case of jacket platforms because it is possible to use the structural elements as the horizontal column of the TLCGD. The objective here is to find the optimum geometric parameters, namely orientation and configuration of vertical columns, length ratio, and area ratio of the TLCGD, considering nonlinear damping of the TLCGD and water-structure interaction between the jacket platform and sea water. The effects of different characteristics of ground motion such as PGA and frequency content on the optimum geometry are also investigated and it is observed that these features have some influence on the optimum area ratio. Finally it is observed that pulse arrangement of ground acceleration is one of the most important parameters affecting the efficiency of a TLCGD. In other words, it is found that the TLCGD's capability to reduce the RMS responses depends only on the frequency content of the ground acceleration, but its capability to reduce the maximum responses depends on both the frequency content and the pulse arrangement of the ground acceleration.

Mousavi, Seyed Amin; Zahrai, Seyed Mehdi; Bargi, Khosrow

2012-12-01

134

Red-light-controllable liquid-crystal soft actuators via low-power excited upconversion based on triplet-triplet annihilation.  

PubMed

A red-light-controllable soft actuator has been achieved, driven by low-power excited triplet-triplet annihilation-based upconversion luminescence (TTA-UCL). First, a red-to-blue TTA-based upconversion system with a high absolute quantum yield of 9.3 0.5% was prepared by utilizing platinum(II) tetraphenyltetrabenzoporphyrin (PtTPBP) as the sensitizer and 9,10-bis(diphenylphosphoryl)anthracene (BDPPA) as the annihilator. In order to be employed as a highly effective phototrigger of photodeformable cross-linked liquid-crystal polymers (CLCPs), the PtTPBP&BDPPA system was incorporated into a rubbery polyurethane film and then assembled with an azotolane-containing CLCP film. The generating assembly film bent toward the light source when irradiated with a 635 nm laser at low power density of 200 mW cm(-2) because the TTA-UCL was effectively utilized by the azotolane moieties in the CLCP film, inducing their trans-cis photoisomerization and an alignment change of the mesogens via an emission-reabsorption process. It is the first example of a soft actuator in which the TTA-UCL is trapped and utilized to create photomechanical effect. Such advantages of using this novel red-light-controllable soft actuator in potential biological applications have also been demonstrated as negligible thermal effect and its excellent penetration ability into tissues. This work not only provides a novel photomanipulated soft actuation material system based on the TTA-UCL technology but also introduces a new technological application of the TTA-based upconversion system in photonic devices. PMID:24088066

Jiang, Zhen; Xu, Ming; Li, Fuyou; Yu, Yanlei

2013-11-01

135

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)

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.

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

2013-03-01

136

Liquid sampling-atmospheric pressure glow discharge as a secondary excitation source for laser ablation-generated aerosols: parametric dependence and robustness to particle loading.  

PubMed

Liquid sampling-atmospheric pressure glow discharge (LS-APGD) microplasma is being developed as a secondary vaporization-excitation source for the optical emission analysis of laser ablation (LA)-generated particle populations. The practicalities of this coupling are evaluated by determining the influence of source parameters on the emission response and the plasma's robustness upon LA introduction of easily ionized elements (EIEs). The influence of discharge current (45-70 mA), LA carrier gas flow rate (0.1-0.8 L min(-1)), and electrode separation distance (0.5-3.5 mm) was studied by measuring Cu emission lines after ablation of a brass sample. Best emission responses were observed for high-discharge currents, low He carrier gas flow rates, and relatively small (<1.5 mm) electrode gaps. Plasma robustness and spectroscopic matrix effects were studied by monitoring Mg(II) : Mg(I) intensity ratios and N2-derived plasma rotational temperatures after the ablation of Sr- and Ca-containing pellets. Plasma robustness investigations showed that the plasma is not appreciably affected by the particle loadings, with the microplasma being slightly more ionizing in the case of Ca introduction. In neither case did the concentration of the concomitant element change the robustness values, implying a high level of robustness. Introduction of the LA particles results in slight increases in the rotational temperatures (?10% relative), with Ca-containing particles having a greater effect than Sr-containing particles. The observed variation of 9% in the plasma rotational temperature is in the same order of magnitude as the short-term reproducibility determined by the proposed LA-LS-APGD system. The determined rotational temperatures ranged from 1047 to 1212 K upon introducing various amounts of Ca and Sr. The relative immunity to LA particle-induced matrix effects is attributed to the relatively long residence times and high power densities (>10 W mm(-3)) of the LS-APGD microplasma. PMID:25506884

Manard, Benjamin T; Konegger-Kappel, Stefanie; Gonzalez, Jhanis J; Chirinos, Jose; Dong, Meirong; Mao, Xianglei; Marcus, R Kenneth; Russo, Richard E

2015-01-01

137

Identifying a Bath-Induced Bose Liquid in Interacting Spin-Boson Models  

NASA Astrophysics Data System (ADS)

We study the ground state phase diagram of a one-dimensional hard-core bosonic model with nearest-neighbor interactions (X X Z model) where every site is coupled Ohmically to an independent but identical reservoir, hereby generalizing spin-boson models to interacting spin-boson systems. We show that a bath-induced Bose liquid phase can occur in the ground state phase diagram away from half filling. This phase is compressible, gapless, and conducting but not superfluid. At half filling, only a Luttinger liquid and a charge density wave are found. The phase transition between them is of Kosterlitz-Thouless type where the Luttinger parameter takes a nonuniversal value. The applied quantum Monte Carlo method can be used for all open bosonic and unfrustrated spin systems, regardless of their dimension, filling factor, and spectrum of the dissipation as long as the quantum system couples to the bath via the density operators.

Cai, Zi; Schollwck, Ulrich; Pollet, Lode

2014-12-01

138

Excite Travel  

NSDL National Science Digital Library

Excite Travel is one of the most comprehensive international guides to communities around the world. Excite Travel provides easy and timely access to information on travel, entertainment, and local business, plus government and community services for all regions of the world.

139

Excited Singlet State Radiative and Nonradiative Transition Probabilities for Acetone, Acetone-d6, and Hexafluoroacetone in the Gas Phase, in Solution, and in the Neat Liquid  

Microsoft Academic Search

Fluorescence lifetime and fluorescence quantum yield measurements have been made on acetone and acetone-d6 in the gas phase, in solution, and in the neat liquid. The variation of the radiative and nonradiative transition probabilities with deuteration, and the effect of solvent environment are discussed. Radiative transition probabilities are compared with those calculated from the equation of Strickler and Berg. The

Arthur M. Halpern; William R. Ware

1971-01-01

140

Excite Assistant  

NSDL National Science Digital Library

Just when the concept of "push" technology seems like yesterday's news, Excite, Inc. produces a handy little program, the Excite Assistant, that pushes data to you without being pushy. The Excite Assistant provides you with instant access to various types of up-to-date information such as the weather for your area, the broadcast TV shows on at the moment, updated stock quotes, your horoscope, and more. The information is summarized within the Assistant's window, but when an item requires expansion, your browser is launched. By far the most useful aspect of this program is the mail notification feature. If you use Excite's Web-based mail service, the Excite Assistant, if active, will play a sound and it's icon will blink when new mail arrives. The Assistant will display the subject line and who the mail is from; clicking on the new mail loads it in your browser. Excite Assistant runs on Win95/98/NT and is free but does display small ads.

141

Stable Manifolds as Thresholds for Multipulse Excitability  

E-print Network

)], Electrodynamic convection in liquid crystals [Peacock et al, J. Fluid Mech. 432 (2001)], Food chains in predator, Nonlinearity 18 (2005), 1095-1120.] PA/BK/HO - Stable manifolds and excitability ­ p. #12;Menu for today

Doedel, Eusebius

142

Magnetostrictive resonance excitation  

DOEpatents

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.

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

1992-01-01

143

Excited Insects  

E-print Network

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

Hacker, Randi

2011-04-06

144

Rashba coupling and magnetic order in correlated helical liquids  

NASA Astrophysics Data System (ADS)

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

Hohenadler, Martin; Assaad, Fakher F.

2014-12-01

145

Excitations in a Bose-condensed Liquid  

Microsoft Academic Search

This volume gives an up-to-date, systematic account of the microscopic theory of Bose-condensed fluids developed since the late 1950s. The core of the present book is the development of the field-theoretic analysis needed to deal with a Bose-condensed fluid. However, the author also brings out the essential physics behind the formal Green's function techniques and presents plausible scenarios to understand

Allan Griffin

1993-01-01

146

Shock wave excited liquid micro-jets  

Microsoft Academic Search

The meniscus of the gas-water interface in a thin hydrophilic capillary of 1mm and less has some similarities to a ``shaped charge'' used to penetrated armored vehicles. In this presentation we show high-speed recordings of the interface dynamics after the reflection from a shock wave: the interface flattens and shapes into a microscopic needle-like jet, which accelerates to velocities of

Claus-Dieter Ohl; Daan Martens; Aaldert Zijlstra; Michel Versluis; Detlef Lohse; Nico de Jong

2006-01-01

147

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

E-print Network

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

Polizzi, Eric

2015-01-01

148

Stimulated Raman scattering imaging by continuous-wave laser excitation  

E-print Network

is demonstrated by excitation of CH stretch vibration. © 2013 Optical Society of America OCIS codes: (140 high cost and complexity of the ultrafast laser sources. Photonic crystal fibers and all-fiber laser microscopy [8]. By cw laser excitation, SRS spectroscopy of liquid benzene was shown in 1977 [9]. Recently

Cheng, Ji-Xin

149

The mathematical modeling of a Tuned Liquid Damper  

E-print Network

and to predict the effectiveness of the Tuned Liquid Damper for structures and excitations not tested in the laboratory. Finally, preliminary designs have been developed for hypothetical deployment of Tuned Liquid Dampers in two real high-rise buildings....

Tokarczyk, Bryan Lee

2012-06-07

150

Quantum shot noise in edge channels  

Microsoft Academic Search

Charge excitations under quantized magnetic field flow in one dimensional-like strips along the edges of the sample. These excitations (quasiparticles) may behave independently (under weaker fields) or con- dense to an interacting chiral Luttinger liquid (under stronger fields). Adding a backscattering potential in the path of the quasiparticles, partitions them, hence inducing quantum shot noise that is proportional to their

M. Heiblum

2006-01-01

151

1999 Macmillan Magazines Ltd 19. Fendley, P. & Saleur, H. Nonequilibrium dc noise in a Luttinger liquid with an impurity. Phys. Rev. B  

E-print Network

by perturbing a static layer of glass beads on a rough inclined plane. We observe two distinct types. The experiments are done on an inclined plane covered with velvet cloth. This surface is chosen so that the glass to understanding their dynamics. When a pile of sand starts flowing, avalanches occur on its inclined free surface

152

From nonequilibrium quantum Brownian motion to impurity dynamics in one-dimensional quantum liquids  

NASA Astrophysics Data System (ADS)

Impurity motion in one-dimensional ultracold quantum liquids confined in an optical trap has attracted much interest recently. As a step towards its full understanding, we construct a generating functional from which we derive the position nonequilibrium correlation function of a quantum Brownian particle with general Gaussian nonfactorizing initial conditions. We investigate the slow dynamics of a particle confined in a harmonic potential after a position measurement; the rapid relaxation of a particle trapped in a harmonic potential after a quantum quench realized as a sudden change in the potential parameters; and the evolution of an impurity in contact with a one-dimensional bosonic quantum gas. We argue that such an impurity-Luttinger-liquid system, which has been recently realized experimentally, admits a simple modeling as quantum Brownian motion in a super-Ohmic bath.

Bonart, Julius; Cugliandolo, Leticia F.

2012-08-01

153

Acoustically excited heated jets. 1: Internal excitation  

NASA Technical Reports Server (NTRS)

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.

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

1988-01-01

154

Non-Fermi-Liquid and Topological States with Strong Spin-Orbit Coupling  

NASA Astrophysics Data System (ADS)

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 Abrikosovs 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 ?xyM0.51.

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

2013-11-01

155

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

PubMed

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

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

2013-11-15

156

Conductivity of a generic helical liquid  

NASA Astrophysics Data System (ADS)

A quantum spin Hall insulator is a two-dimensional state of matter consisting of an insulating bulk and one-dimensional helical edge states. While these edge states are topologically protected against elastic backscattering in the presence of disorder, interaction-induced inelastic terms may yield a finite conductivity. By using a kinetic equation approach, we find the backscattering rate ?-1 and the semiclassical conductivity in the regimes of high (? ??-1) and low (? ??-1) frequency. By comparing the two limits, we find that the parametric dependence of conductivity is described by the Drude formula for the case of a disordered edge. On the other hand, in the clean case where the resistance originates from umklapp interactions, the conductivity takes a non-Drude form with a parametric suppression of scattering in the dc limit as compared to the ac case. This behavior is due to the peculiarity of umklapp scattering processes involving necessarily the state at the "Dirac point." In order to take into account Luttinger liquid effects, we complement the kinetic equation analysis by treating interactions exactly in bosonization and calculating conductivity using the Kubo formula. In this way, we obtain the frequency and temperature dependence of conductivity over a wide range of parameters. We find the temperature and frequency dependence of the transport scattering time in a disordered system as ? [max(?,T)]-2K-2, for K >2/3 and ? [max(?,T)]-8K+2 for K <2/3.

Kainaris, Nikolaos; Gornyi, Igor V.; Carr, Sam T.; Mirlin, Alexander D.

2014-08-01

157

BROADBAND EXCITATION IN NUCLEAR MAGNETIC RESONANCE  

SciTech Connect

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.

Tycko, R.

1984-10-01

158

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

159

Photobleaching and reorientational dynamics of dyes in a nematic liquid crystal M. Nollmann and D. Shalom  

E-print Network

Received 25 August 1998 The polarized fluorescence of excited dyes in a prototype nematic liquid crystalPhotobleaching and reorientational dynamics of dyes in a nematic liquid crystal M. No¨llmann and D of the liquid crystal, if the dyes are resonantly excited. The fluorescence emission in this latter case is able

Nollmann, Marcelo

160

Optical Kerr effect in liquids  

Microsoft Academic Search

An experimental study was undertaken to measure the optical Kerr effect (OKE) in liquids induced by picosecond laser pulses. The effects of different parameters on the dynamics of the OKE are described. The following parameters were investigated: the spatial and temporal profiles of the laser pulses, the intensity of the exciting laser pulse, the length of the Kerr gate, the

P. P. Ho; R. R. Alfano

1979-01-01

161

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

NASA Astrophysics Data System (ADS)

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.

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

1992-08-01

162

Sloshing motions in excited tanks  

NASA Astrophysics Data System (ADS)

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].

Frandsen, Jannette B.

2004-05-01

163

Modeling the configurational entropy of supercooled liquids and a  

E-print Network

heat capacity. This is the case of fragile liquids! Criticality and a meanfield firstorder transition must be parts of the model! #12; performance against experiment Fragile liquids are found the relations (fragile liquids only): Entropy of excitations appears as the only parameter describing fragility

Matyushov, Dmitry

164

Positive Cross Correlations in a Three-Terminal Quantum Dot with Ferromagnetic Contacts A. Cottet, W. Belzig, and C. Bruder  

E-print Network

injection of electrons by a voltage probe [11], or due to correlated excitations in a Luttinger liquid [12 with capacitances Ci and net spin-inde- pendent tunneling rates i (inset of Fig. 1). Avoltage bias V is applied level spacin

Cottet, Audrey

165

Electronic excitations of fluoroethylenes  

NASA Astrophysics Data System (ADS)

Several lowest-lying singlet electronic states of vinyl fluoride, trans-, cis-, and 1,1-difluoroethylene, trifluoroethylene, and tetrafluoroethylene were investigated by using symmetry-adapted cluster configuration interaction theory. Basis sets up to Dunning's aug-cc-pVTZ augmented with appropriate Rydberg functions were utilized for the calculations. Calculated excitation energies show a good agreement with the available experimental values. Even in the troublesome ? ??* transitions, the excitation energies obtained in the present study agree well with the experimental values except in one or two fluoroethylenes. Strong mixing between different states was noticed in a few fluoroethylenes; especially the mixing is very strong between ?-? * and ?-3p? states in trifluoroethylene. No pure ?-? * excited state was found in almost all the fluoroethylenes. Several assignments and reassignments of features in the experimental spectra were suggested. The present study does not support the existing argument that the interaction between the ?-? * and ?-? * states is the reason behind the blueshift of around 1.25eV in the ?-?* excitation energy of tetrafluoroethylene. Possible reasons, including structural changes, for this shift are discussed in detail. Several low-lying triplet excited states were also studied.

Arulmozhiraja, Sundaram; Ehara, Masahiro; Nakatsuji, Hiroshi

2007-01-01

166

Electronic excitations of fluoroethylenes.  

PubMed

Several lowest-lying singlet electronic states of vinyl fluoride, trans-, cis-, and 1,1-difluoroethylene, trifluoroethylene, and tetrafluoroethylene were investigated by using symmetry-adapted cluster configuration interaction theory. Basis sets up to Dunning's aug-cc-pVTZ augmented with appropriate Rydberg functions were utilized for the calculations. Calculated excitation energies show a good agreement with the available experimental values. Even in the troublesome pi-->pi(*) transitions, the excitation energies obtained in the present study agree well with the experimental values except in one or two fluoroethylenes. Strong mixing between different states was noticed in a few fluoroethylenes; especially the mixing is very strong between pi-pi(*) and pi-3ppi states in trifluoroethylene. No pure pi-sigma(*) excited state was found in almost all the fluoroethylenes. Several assignments and reassignments of features in the experimental spectra were suggested. The present study does not support the existing argument that the interaction between the pi-pi(*) and sigma-sigma(*) states is the reason behind the blueshift of around 1.25 eV in the pi-pi(*) excitation energy of tetrafluoroethylene. Possible reasons, including structural changes, for this shift are discussed in detail. Several low-lying triplet excited states were also studied. PMID:17286469

Arulmozhiraja, Sundaram; Ehara, Masahiro; Nakatsuji, Hiroshi

2007-01-28

167

Exciting flavored bound states  

NASA Astrophysics Data System (ADS)

We study ground and radial excitations of flavor singlet and flavored pseudoscalar mesons within the framework of the rainbow-ladder truncation using an infrared massive and finite interaction in agreement with recent results for the gluon-dressing function from lattice QCD and Dyson-Schwinger equations. Whereas the ground-state masses and decay constants of the light mesons as well as charmonia are well described, we confirm previous observations that this truncation is inadequate to provide realistic predictions for the spectrum of excited and exotic states. Moreover, we find a complex conjugate pair of eigenvalues for the excited D(s) mesons, which indicates a non-Hermiticity of the interaction kernel in the case of heavy-light systems and the present truncation. Nevertheless, limiting ourselves to the leading contributions of the Bethe-Salpeter amplitudes, we find a reasonable description of the charmed ground states and their respective decay constants.

Rojas, E.; El-Bennich, B.; de Melo, J. P. B. C.

2014-10-01

168

Quasiparticle excitations in Bose-Fermi mixtures  

NASA Astrophysics Data System (ADS)

We analyze the excitation spectrum of a three-dimensional Bose-Fermi mixture with tunable resonant interaction parameters and high hyperfine spin multiplets. We focus on a three-particle vertex describing fermionic and bosonic atoms which can scatter to create fermionic molecules or disassociate. For a single molecular level, in analogy to the single magnetic impurity problem we argue that the low-lying excitations of the mean-field theory are described by the Fermi-liquid picture with a quasiparticle weight and charge which is justified by a 1/N? expansion, expected to be exact in the limit of infinite degeneracy (or very high fermionic spin) N??? . Our emphasis is placed on the novel conditions for chemical equilibrium and how many-body chemical reactions renormalize the bosonic chemical potential, modifying condensation and superfluid-insulator transitions.

Akhanjee, Shimul

2010-08-01

169

Photothermal excitation setup for a modified commercial atomic force microscope  

SciTech Connect

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

Adam, Holger; Rode, Sebastian; Schreiber, Martin; Khnle, Angelika, E-mail: kuehnle@uni-mainz.de [Institute of Physical Chemistry, Johannes Gutenberg University Mainz, Duesbergweg 10-14, 55099 Mainz (Germany)] [Institute of Physical Chemistry, Johannes Gutenberg University Mainz, Duesbergweg 10-14, 55099 Mainz (Germany); Kobayashi, Kei; Yamada, Hirofumi [Department of Electronic Science and Engineering, Kyoto University, Katsura, Nishikyo, Kyoto 615-8510 (Japan)] [Department of Electronic Science and Engineering, Kyoto University, Katsura, Nishikyo, Kyoto 615-8510 (Japan)

2014-02-15

170

Photothermal excitation setup for a modified commercial atomic force microscope  

NASA Astrophysics Data System (ADS)

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

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

2014-02-01

171

Photothermal excitation setup for a modified commercial atomic force microscope.  

PubMed

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

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

2014-02-01

172

Ultrasonic excitation by amplitude-modulated diode laser  

Microsoft Academic Search

A laser-ultrasonic transducer was newly developed for the purpose of exciting ultrasonic wave in UHF range with flat frequency response. An infrared semiconductor laser whose output power is modulated with sinusoidal driving current illuminates a thin metal film formed on a flat surface of a solid rod immersed in a sample liquid. The heat generated in the film causes periodical

K. Sakai; H. Tanaka; K. Hattori; K. Takagi

1997-01-01

173

Fluorescent optical liquid level sensor  

DOEpatents

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.

Weiss, Jonathan D. (Albuquerque, NM)

2001-01-01

174

Microscopic Dynamics of Liquid Aluminum Oxide  

Microsoft Academic Search

Collective excitations have been observed in liquid aluminum oxide at high temperatures by combining a containerless sample environment with inelastic x-ray scattering. The excitation spectra show a well-defined triplet peak structure at lower wave vectors Q (1 to 6 nanometers-1) and a single quasi-elastic peak at higher Q. The high-Q spectra are well described by kinetic theory. The low-Q spectra

H. Sinn; B. Glorieux; L. Hennent; A. Alatas; M. Hu; E. E. Alp; F. J. Bermejo; D. L. Price; M.-L. Saboungi; APS-USR

2003-01-01

175

Liquid nitrogen  

MedlinePLUS

Liquid nitrogen is a chemical that is super cold, about -200 degrees Celsius. Liquid nitrogen will instantly freeze anything it touches. It is used to kill cells that make up diseased or cancerous tissue. Tissue that has been frozen dries out and falls off.

176

Microscopic dynamics of liquid aluminum oxide.  

PubMed

Collective excitations have been observed in liquid aluminum oxide at high temperatures by combining a containerless sample environment with inelastic x-ray scattering. The excitation spectra show a well-defined triplet peak structure at lower wave vectors Q (1 to 6 nanometers-1) and a single quasi-elastic peak at higher Q. The high-Q spectra are well described by kinetic theory. The low-Q spectra require a frequency-dependent viscosity and provide previously unknown experimental constraints on the behavior of liquids at the interface between atomistic and continuum theory. PMID:12663922

Sinn, H; Glorieux, B; Hennet, L; Alatas, A; Hu, M; Alp, E E; Bermejo, F J; Price, D L; Saboungi, M-L

2003-03-28

177

Liquid pearls  

E-print Network

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

Bremond, Nicolas; Bibette, Jrme

2010-01-01

178

Temperature and excitable cells  

PubMed Central

Temperature affects a host of biological processes, one of which is the conduction velocity of action potentials (AP). The velocity-temperature profile of APs has remained remarkably conserved across excitable animal and plant cells. Herein, we will not analyze this behavior in terms of temperature sensitivities of single molecules (e.g., ion channels), but rather we present a phenomenological thermodynamic interpretation. By assuming that APs are acoustic phenomena, one arrives at testable predictions about the temperature-dependence of the macroscopic material properties of the excitable cell membrane. These material properties set constraints on the excitability of a cell membrane and allow us to hypothesize about its typical relaxation timescales. The presented approachby virtue of its thermodynamic natureis by no means limited to temperature. It applies equally well to all thermodynamic variables (e.g., mechanical stretch, pH, ion concentrations, etc.) and to underline this argument we discuss some implications and predictions for sensory physiology. PMID:24563710

Fillafer, Christian; Schneider, Matthias F

2013-01-01

179

Pulse excitation of bolometer bridges  

NASA Technical Reports Server (NTRS)

Driving bolometer bridge by appropriately phased excitation pulses increases signal-to-noise ratio of bolometer sensor which operates on a chopped light beam. Method allows higher applied voltage than is possible by conventional ac or dc excitation.

Rusk, S. J.

1972-01-01

180

Apparatus for photon excited catalysis  

NASA Technical Reports Server (NTRS)

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.

Saffren, M. M. (inventor)

1977-01-01

181

Liquid metal thermoacoustic engine  

SciTech Connect

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.

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

1986-01-01

182

Algebraic spin liquid in an exactly solvable spin model  

SciTech Connect

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.'

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

2010-03-25

183

Hole propagator of the chiral spin liquid  

SciTech Connect

The properties of a class of wave functions describing charged spinless excitations of the Kalmeyer-Laughlin spin-liquid state are studied within the context of the {ital t}-{ital J} model and the case made that they are legitimate elementary excitations of such a state. Using these wave functions and those previously proposed for the neutral spin-1/2 excitations, a variational calculation of the hole propagator is performed. The spectral density at a given momentum is found to be a broad continuum with resonant structures that move as the momentum is varied, and to be consistent with exact-diagonalization studies.

Laughlin, R.B. (Department of Physics, Stanford University, Stanford, California 94305 (United States) Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94550 (United States))

1992-01-01

184

Dynamics of the edge excitations in the FQH effects  

SciTech Connect

Fractional quantum Hall effects (FQHE) discovered by Tsui, Stormer and Gossard open a new era in theory of strongly correlated system. In the first time the authors have to completely abandon the theories based on the single-body picture and use an intrinsic many-body theory proposed by Laughlin and others to describe the FQHE. Due to the repulsive interaction, the strongly correlated FQH liquid is an incompressible state despite the first Landau level is only partially filled. All the bulk excitations in the FQH states have finite energy gaps. The FQH states and insulators are similar in the sense that both states have finite energy gap and short ranged electron propagators. Because of this similarity, it is puzzling that the FQH systems apparently have very different transport properties than ordinary insulators. Halperin first point out that the integral quantum Hall (IQH) states contain gapless edge excitations. Although the electronic states in the bulk are localized, the electronic states at the edge of the sample are extended. Therefore the nontrivial transport properties of the IQH states come from the gapless edge excitations. Such an edge transport picture has been supported by many experiments. One also found that the edge excitations in the IQH states are described by a chiral 1D Fermi liquid theory. Here, the authors review the dynamical theory of the edge excitations in the FQH effects.

Wen, X.G. [Massachusetts Inst. of Tech., Cambridge, MA (United States). Dept. of Physics

1994-02-14

185

Exploring Liquids  

NSDL National Science Digital Library

Young learners investigate and observe the properties of three liquids -- water, vegetable oil, and corn syrup. They use their senses to collect data and ask and answer questions. This lesson for young learners introduces the scientific process.

Janulaw, Sharon

2010-01-01

186

Modal analysis of Lamb wave generation in elastic plates by liquid wedge transducers  

Microsoft Academic Search

A modal analysis is presented to describe the excitation of Lamb waves in an elastic plate using a liquid wedge transducer. Analytical expression for the displacement of a given mode is derived for the excitation by a uniform bounded beam. In contrast to previous studies, the contribution of the reflected wave is included in the input exciting forces using a

X. Jia

1997-01-01

187

Spin liquids in frustrated magnets.  

PubMed

Frustrated magnets are materials in which localized magnetic moments, or spins, interact through competing exchange interactions that cannot be simultaneously satisfied, giving rise to a large degeneracy of the system ground state. Under certain conditions, this can lead to the formation of fluid-like states of matter, so-called spin liquids, in which the constituent spins are highly correlated but still fluctuate strongly down to a temperature of absolute zero. The fluctuations of the spins in a spin liquid can be classical or quantum and show remarkable collective phenomena such as emergent gauge fields and fractional particle excitations. This exotic behaviour is now being uncovered in the laboratory, providing insight into the properties of spin liquids and challenges to the theoretical description of these materials. PMID:20220838

Balents, Leon

2010-03-11

188

Ionic Liquids  

Microsoft Academic Search

Ionic liquids are receiving an upsurge of interest as green solvents; primarily as replacements for conventional media in\\u000a chemical processes. This review presents an overview of the chemistry that has been developed utilising ionic liquids as either\\u000a catalyst and\\/or solvent, with particular emphasis on processes that have been taken beyond the pre-competetive laboratory\\u000a stage and represent clean industrial technology with

J. D. Holbrey; K. R. Seddon

1999-01-01

189

Multiphoton excitation of organic chromophores in microbubble resonators  

NASA Astrophysics Data System (ADS)

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.

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

2014-03-01

190

Collective excitations in soft-sphere fluids  

NASA Astrophysics Data System (ADS)

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.

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

2014-10-01

191

Collective excitations in soft-sphere fluids.  

PubMed

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

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

2014-10-01

192

Multiphonon excitations in boson quantum films  

SciTech Connect

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.}

Clements, B.E. [Institute Laue Langevin, 38042 Grenoble Cedex (France)] [Institute Laue Langevin, 38042 Grenoble Cedex (France); [Department of Physics, Texas A& M University, College Station, Texas 77843 (United States); Krotscheck, E. [Institut fuer Theoretische Physik, Johannes Kepler Universitaet, A-4040 Linz (Austria)] [Institut fuer Theoretische Physik, Johannes Kepler Universitaet, A-4040 Linz (Austria); [Department of Physics, Texas A& M University, College Station, Texas 77843 (United States); Tymczak, C.J. [Department of Physics, Texas A& M University, College Station, Texas 77843 (United States)] [Department of Physics, Texas A& M University, College Station, Texas 77843 (United States)

1996-05-01

193

Excitability in Dictyostelium development  

NASA Astrophysics Data System (ADS)

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.

Schwab, David

2013-03-01

194

The optical tensor configuration in a surface stabilized ferroelectric liquid crystal determined by using half leaky guided modes  

Microsoft Academic Search

The optic tensor configuration in a surface stabilized ferroelectric liquid crystal cell is investigated using optical excitation of half leaky guided modes. A thin ferroelectric liquid crystal layer is confined between a high index pyramid, with an index greater than the maximum of the liquid crystal, and a glass substrate having an index less than the minimum of the liquid

Fuzi Yang; J. R. Sambles

1993-01-01

195

Negative Meson Absorption in Liquid Hydrogen  

Microsoft Academic Search

A theoretical study has been made of the atomic processes involved in the absorption of pi- and K- mesons in liquid hydrogen, with the main purpose of setting an upper limit on the fraction of K mesons that react with the proton from the P state. The principal mode of de-excitation of the mesonic atom, Auger ionization of neighboring hydrogen

Melvin Leon; H. A. Bethe

1962-01-01

196

Electron-beam pumped liquid excimer lasers  

SciTech Connect

We have investigated the excimers formed in liquid argon when various cryogenic gas mixes were excited by 1-MeV electrons. Fluorescence was detected from many excimers at their new red-shifted wavelengths, and XeO, Xe/sub 2/, and Kr/sub 2/ were lased. 25 refs., 12 figs.

Loree, T.R.; Showalter, R.R.; Johnson, T.M.; Birmingham, B.S.; Hughes, W.M.

1988-01-01

197

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

E-print Network

on the dissociation dynamics. Modeling the OH geminate recombination indicates that the dissociating H atoms have enough kinetic energy to escape the solvent cage and one or two additional solvent shells. The average initial separation of H and OH fragments is 0.70.2...

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

2007-04-25

198

Fusion excitation function revisited  

E-print Network

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

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

2012-09-28

199

STUDIES OF EXCITABLE MEMBRANES  

PubMed Central

The neuromuscular junctions and nonjunctional sarcolemmas of mammalian skeletal muscle fibers were studied by conventional thin-section electron microscopy and freeze-fracture techniques. A modified acetylcholinesterase staining procedure that is compatible with light microscopy, conventional thin-section electron microscopy, and freeze-fracture techniques is described. Freeze-fracture replicas were utilized to visualize the internal macromolecular architecture of the nerve terminal membrane, the chemically excitable neuromuscular junction postsynaptic folds, and the electrically excitable nonjunctional sarcolemma. The nerve terminal membrane is characterized by two parallel rows of 100110- particles which may be associated with synpatic vesicle fusion and release. On the postsynpatic folds, irregular rows of densely packed 110140- particles were observed and evidence is assembled which indicates that these large transmembrane macromolecules may represent the morphological correlate for functional acetylcholine receptor activity in mammalian motor endplates. Differences in the size and distribution of particles in mammalian as compared with amphibian and fish postsynaptic junctional membranes are correlated with current biochemical and electron micrograph autoradiographic data. Orthogonal arrays of 60- particles were observed in the split postsynaptic sarcolemmas of many diaphragm myofibers. On the basis of differences in the number and distribution of these "square" arrays within the sarcolemmas, two classes of fibers were identified in the diaphragm. Subsequent confirmation of the fiber types as fast- and slow-twitch fibers (Ellisman et al. 1974. J. Cell Biol. 63[2, Pt. 2]:93 a. [Abstr.]) may indicate a possible role for the square arrays in the electrogenic mechanism. Experiments in progress involving specific labeling techniques are expected to permit positive identification of many of these intriguing transmembrane macromolecules. PMID:4138515

Rash, John E.; Ellisman, Mark H.

1974-01-01

200

Slosh wave excitation associated with high frequency impulsive reverse gravity acceleration of geyser initiation  

NASA Astrophysics Data System (ADS)

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 spacecraft propellant tank prior to main engine restart poses a microgravity fluid behavior problem. The purpose of this 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 flowfield activated by 10-Hz high-frequency impulsive reverse gravity acceleration during the course of liquid fluid 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.

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

201

Optically excited states in positronium  

NASA Technical Reports Server (NTRS)

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

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

1990-01-01

202

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

NASA Technical Reports Server (NTRS)

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.

Oliva, J.; Ashcroft, N. W.

1981-01-01

203

Fluid excitation forces acting on a tube array  

SciTech Connect

Fluid forces are important in the assessment of vibration of the Space Shuttle Main Engine liquid oxygen posts. This report summarizes the available data on fluid excitation forces acting on tube arrays in turbulent crossflow, and test results for an array of tubes subject to turbulent flow. The fluctuating drag and lift forces are measured as a function of Reynolds number, incoming flow conditions, and tube location in an array.

Chen, S.S.; Jendrzejczyk, J.A.

1985-09-01

204

Quantum Spin Liquids and Fractionalization  

NASA Astrophysics Data System (ADS)

This chapter discusses quantum antiferromagnets which do not break any symmetries at zero temperature - also called "spin liquids" - and focuses on lattice spin models with Heisenberg-like (i.e. SU(2)-symmetric) interactions in dimensions larger than one. We begin by discussing the Lieb-Schultz-Mattis theorem and its recent extension to D > 1 by Hastings (2004), which establishes an important distinction between spin liquids with an integer and with a half-integer spin per unit cell. Spin liquids of the first kind, "band insulators", can often be understood by elementary means, whereas the latter, "Mott insulators", are more complex (featuring "topological order") and support spin-1/2 excitations (spinons). The fermionic formalism (Affleck and Marston, 1988) is described and the effect of fluctuations about mean-field solutions, such as the possible creation of instabilities, is discussed in a qualitative way. In particular, we explain the emergence of gauge modes and their relation to fractionalization. The concept of the projective symmetry group (X.-G. Wen, 2002) is introduced, with the aid of some examples. Finally, we present the phenomenology of (gapped) short-ranged resonating-valence-bond spin liquids, and make contact with the fermionic approach by discussing their description in terms of a fluctuating Z 2 gauge field. Some recent references are given to other types of spin liquid, including gapless ones.

Misguich, Grgoire

205

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

PubMed

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

Spasic, Aleksandar M; Lazarevic, Mihailo P

2005-02-01

206

Gaussian excitations model for glass-former dynamics and thermodynamics  

E-print Network

We describe a model for the thermodynamics and dynamics of glass-forming liquids in terms of excitations from an ideal glass state to a Gaussian manifold of configurationally excited states. The quantitative fit of this three parameter model to the experimental data on excess entropy and heat capacity shows that ``fragile'' behavior, indicated by a sharply rising excess heat capacity as the glass transition is approached from above, occurs in anticipation of a first-order transition -- usually hidden below the glass transition -- to a ``strong'' liquid state of low excess entropy. The dynamic model relates relaxation to a hierarchical sequence of excitation events each involving the probability of accumulating sufficient kinetic energy on a separate excitable unit. Super-Arrhenius behavior of the relaxation rates, and the known correlation of kinetic with thermodynamic fragility, both follow from the way the rugged landscape induces fluctuations in the partitioning of energy between vibrational and configurational manifolds. A relation is derived in which the configurational heat capacity, rather than the configurational entropy of the Adam Gibbs equation, controls the temperature dependence of the relaxation times, and this gives a comparable account of the experimental observations.

Dmitry V. Matyushov; C. A. Angell

2006-12-26

207

Layered Liquids  

NSDL National Science Digital Library

This activity involves an exploration of density. Why does oil float on water? How does drain cleaner sink down into the clogged pipe right through standing water? These questions will be answered as students make a layered "parfait" of colored liquids ba

Eichinger, John

2009-05-30

208

Attosecond Photoscopy of Plasmonic Excitations  

NASA Astrophysics Data System (ADS)

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.

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

2014-09-01

209

Attosecond photoscopy of plasmonic excitations.  

PubMed

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 insitu. PMID:25259981

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

2014-09-12

210

O the Microscopic Theory of Liquid HELIUM-4  

NASA Astrophysics Data System (ADS)

A microscopic description of the ground state and elementary excitations of liquid ('4)He is presented. The variational theory is used in conjunction with a perturbative scheme called correlated basis perturbation theory. The hypernetted-chain technique is used to calculate the various matrix elements. First, the ground state calculations are reviewed with emphasis on the most recent variational calculations. The best available variational wave functions are used to calculate the momentum distribution of the atoms in the ground state and the condensate fraction. We, then, study in detail the energy spectrum of an elementary excitation traveling with momentum (')k in the liquid. A perturbation theory in a correlated basis generated by Feynman-Cohen (FC) excitations is developed. The expansion in this basis appears to have good convergence. We calculate, up to second order, the effects of the coupling of the one FC excitation to two FC excita- tions. These corrections to the FC excitations bring the theory in close agreement with the neutron scattering measurements. This perturbation expansion is also used to microscopically calculate the dynamic liquid structure function S(k,(omega)), known from neutron inelastic scattering experiments. The calculated strength Z(k) of the one quasiparticle excitation and the contribution of the two quasiparticle states to S(k,(omega)) are in semiquantitative agreement with those inferred from the data. Finally, the structure of the excitations is studied by evaluating the change (delta)n(,(,k))((')p) in the momentum distribution of the particles due to the creation of one quasiparticle excitation traveling with momen- tum (')k in the liquid. This study provides an insight in the nature of the elementary excitations; it brings out the collective and "quasi-free particle" character of the excitations in the long and short wave length limits respectively, and the interplay between these two behaviours at intermediate momenta. The (delta)n(,(,k))((')p) is used to deter- mine the momentum distribution and condensate fraction at low temperatures.

Manousakis, Efstratios

211

Excited waves in shear layers  

NASA Technical Reports Server (NTRS)

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.

Bechert, D. W.

1982-01-01

212

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

NASA Astrophysics Data System (ADS)

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.

Yano, Yuichiro; Goka, Shigeyoshi

2012-12-01

213

Low-density electron liquid  

NASA Astrophysics Data System (ADS)

We present an exchange-antisymmetric calculation of the particle-hole interaction in the low-density electron liquid. Long-range screening of the Coulomb interaction is incorporated in a self-consistent manner, and we discuss the general method of incorporating screening, both long range and short range, within this framework. The scattering amplitude is separated into a short-range direct part and a long-range induced interaction. The short-range part includes the effects of short-range electron-electron correlations phenomenologically via polarization potentials. The long-range piece arises from the exchange of particle-hole excitations. These particle-hole excitations provide the screening of the bare Coulomb interaction in the q-->0 limit.

Ainsworth, T. L.; Green, F.; Pines, D.

1990-12-01

214

Liquid electrode  

DOEpatents

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.

Ekechukwu, Amy A. (Augusta, GA)

1994-01-01

215

Coherent control of multiple vibrational excitations for optimal detection  

NASA Astrophysics Data System (ADS)

While the means to selectively excite a single vibrational mode using ultrafast pulse shaping are well established, the subsequent problem of selectively exciting multiple vibrational modes simultaneously has been largely neglected. The coherent control of multiple vibrational excitations has applications in control of chemistry, chemical detection and molecular vibrational quantum information processing. Using simulations and experiments, we demonstrate that multiple vibrational modes can be selectively excited with the concurrent suppression of multiple interfering modes by orders of magnitude. While the mechanism of selectivity is analogous to that of single mode selectivity, the interferences required to select multiple modes require complicated non-intuitive pulse trains. Additionally, we show that selective detection can be achieved by the optimal pulse shape, even when the nature of the interfering species is varied, suggesting that optimized detection should be practical in real world applications. Experimental measurements of the multiplex coherent anti-Stokes Raman spectra (CARS) and CARS decay times of toluene, acetone, cis-stilbene and nitromethane liquids are reported, along with optimizations attempting to selectively excite nitromethane in a mixture of the four solvents. The experimental implementation exhibits a smaller degree of signal to background enhancement than predicted, which is primarily attributed to the single objective optimization methodology and not to fundamental limitations.

McGrane, S. D.; Scharff, R. J.; Greenfield, M.; Moore, D. S.

2009-10-01

216

Radioactivity Induced by Nuclear Excitation I. Excitation by Neutrons  

Microsoft Academic Search

It is shown that the 4.1-hr. period of indium can be produced by nuclear excitation of indium and is to be attributed to an excited metastable state, In115,* of the stable In115. This result is obtained by studying the radioactivity produced in indium by neutrons of different energy distributions and by studying the chain reactions produced in cadmium by fast

M. Goldhaber; R. D. Hill; Leo Szilard

1939-01-01

217

Industrial applications of photonuclear resonance excitation  

E-print Network

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

Chichester, David Lee, 1971-

2000-01-01

218

Chiral non-Fermi liquids  

NASA Astrophysics Data System (ADS)

A non-Fermi liquid state without time-reversal and parity symmetries arises when a chiral Fermi surface is coupled with a soft collective mode in two space dimensions. The full Fermi surface is described by a direct sum of chiral patch theories, which are decoupled from each other in the low-energy limit. Each patch includes low-energy excitations near a set of points on the Fermi surface with a common tangent vector. General patch theories are classified by the local shape of the Fermi surface, the dispersion of the critical boson, and the symmetry group, which form the data for distinct universality classes. We prove that a large class of chiral non-Fermi liquid states exists as stable critical states of matter. For this, we use a renormalization group scheme where low-energy excitations of the Fermi surface are interpreted as a collection of (1+1)-dimensional chiral fermions with a continuous flavor labeling the momentum along the Fermi surface. Due to chirality, the Wilsonian effective action is strictly UV finite. This allows one to extract the exact scaling exponents although the theories flow to strongly interacting field theories at low energies. In general, the low-energy effective theory of the full Fermi surface includes patch theories of more than one universality classes. As a result, physical responses include multiple universal components at low temperatures. We also point out that, in quantum field theories with extended Fermi surface, a noncommutative structure naturally emerges between a coordinate and a momentum which are orthogonal to each other. We show that the invalidity of patch description for Fermi liquid states is tied with the presence of UV/IR mixing associated with the emergent noncommutativity. On the other hand, UV/IR mixing is suppressed in non-Fermi liquid states due to UV insensitivity, and the patch description is valid.

Sur, Shouvik; Lee, Sung-Sik

2014-07-01

219

Exciting Students About Science & Engineering ...  

E-print Network

applications include nanomachines, bioimplants, smart materials, fuel cells, genetic engineering and spaceExciting Students About Science & Engineering ... ASM MATERIALS CAMP® 2013 MATERIALS IN TODAY'S WORLD Materials science and engineering is a study of the relationship between the structure

Evans, Paul G.

220

Parametric Excitation of a DWSC  

E-print Network

methods of analysis and the effect of damping (especially viscous drag) on parametric excitation and instability. The thesis uses Mathieu's equation as the basis for stability analysis and time-simulates the coupled heave-sway-roll EOM. Time...

Lakhotia, Chandan

2011-08-08

221

Laser-induced nuclear excitation  

SciTech Connect

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.

Zon, B. A., E-mail: zon@niif.vsu.ru; Kornev, A. S., E-mail: a-kornev@yandex.r [Voronezh State University (Russian Federation)

2010-05-15

222

Redox Control of Cardiac Excitability  

PubMed Central

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, 432468. PMID:22897788

Aggarwal, Nitin T.

2013-01-01

223

Electron-excited molecule interactions  

SciTech Connect

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.

Christophorou, L.G. (Oak Ridge National Lab., TN (USA) Tennessee Univ., Knoxville, TN (USA). Dept. of Physics)

1991-01-01

224

Electrostatic Tuning of Cellular Excitability  

PubMed Central

Abstract Voltage-gated ion channels regulate the electric activity of excitable tissues, such as the heart and brain. Therefore, treatment for conditions of disturbed excitability is often based on drugs that target ion channels. In this study of a voltage-gated K channel, we propose what we believe to be a novel pharmacological mechanism for how to regulate channel activity. Charged lipophilic substances can tune channel opening, and consequently excitability, by an electrostatic interaction with the channel's voltage sensors. The direction of the effect depends on the charge of the substance. This was shown by three compounds sharing an arachidonyl backbone but bearing different charge: arachidonic acid, methyl arachidonate, and arachidonyl amine. Computer simulations of membrane excitability showed that small changes in the voltage dependence of Na and K channels have prominent impact on excitability and the tendency for repetitive firing. For instance, a shift in the voltage dependence of a K channel with ?5 or +5 mV corresponds to a threefold increase or decrease in K channel density, respectively. We suggest that electrostatic tuning of ion channel activity constitutes a novel and powerful pharmacological approach with which to affect cellular excitability. PMID:20141752

Brjesson, Sara I.; Parkkari, Teija; Hammarstrm, Sven; Elinder, Fredrik

2010-01-01

225

46 CFR 111.12-3 - Excitation.  

Code of Federal Regulations, 2013 CFR

...COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) ELECTRICAL ENGINEERING ELECTRIC SYSTEMS-GENERAL REQUIREMENTS Generator Construction and Circuits 111.12-3 Excitation. In general, excitation must meet...

2013-10-01

226

46 CFR 111.12-3 - Excitation.  

Code of Federal Regulations, 2011 CFR

...COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) ELECTRICAL ENGINEERING ELECTRIC SYSTEMS-GENERAL REQUIREMENTS Generator Construction and Circuits 111.12-3 Excitation. In general, excitation must meet...

2011-10-01

227

46 CFR 111.12-3 - Excitation.  

Code of Federal Regulations, 2012 CFR

...COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) ELECTRICAL ENGINEERING ELECTRIC SYSTEMS-GENERAL REQUIREMENTS Generator Construction and Circuits 111.12-3 Excitation. In general, excitation must meet...

2012-10-01

228

Gravity jitters excited slosh waves in rotating propellant tank under microgravity environment  

NASA Technical Reports Server (NTRS)

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 tank without probe imposed by various frequencies of gravity jitters have been investigated. Results disclose the conditions for the excitation of large amplitude slosh waves which shall be avoided in the design of cryogenic liquid propellant system.

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

1991-01-01

229

Gravity jitters excited slosh waves in rotating propellant tank under microgravity environment  

NASA Astrophysics Data System (ADS)

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 tank without probe imposed by various frequencies of gravity jitters have been investigated. Results disclose the conditions for the excitation of large amplitude slosh waves which shall be avoided in the design of cryogenic liquid propellant system.

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

230

Liquid electrode  

DOEpatents

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.

Ekechukwu, A.A.

1994-07-05

231

Laser-induced separation of hydrogen isotopes in the liquid phase  

DOEpatents

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.

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

1980-01-01

232

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

DOEpatents

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.

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

2005-07-05

233

Electronic excitations in conducting polymers  

NASA Astrophysics Data System (ADS)

The subject of this dissertation is the excited electronic states of conducting polymers. With one exception, the experimental techniques used in this study are spectroscopies, in particular modulation spectroscopies. There are two major types of excited electronic states in conducting polymers: (1) excitons that have energies above the optical gap and (2) electronic excitations (here denoted 'excitations' as opposed to 'excitons') with energies below the optical gap. Excitations occur with a modulation of the bond length order; thus they are highly dependent on the topological structure of the polymer. In this study both excitons and excitations in conducting polymers with different topological structure are characterized, and their decay processes analyzed. The results are important for theoretical considerations, experimental work, and technological developments. This study provides evidence that the classical description of ?-conjugated polymers with a band model and neglecting electron-electron interactions must be reconsidered. Instead, a model that involves strong electron-electron interactions and takes into account the effects of disorder in real conducting polymers can describe the behavior of excitons and excitations (Chapter 5, Chapter 3). The results on exciton polarizability (Chapter 3) indicate that measurements of fast photocurrent must be explained in terms of exciton and excitation polarizability. This polarizability is highly dependent of the quality of the material (conjugation length distribution). A new experimental technique, electromodulated photoinduced absorption (EPA), is presented (Chapter 4) that allows the experimentalist to distinguish between photoinduced absorption signatures of different photoexcitations. The study (Chapter 5) on bisubstituted polyacetylenes shows how polymers must be engineered in order to achieve luminescence. The luminescence is not an effect of the topological structure of the material. It is an effect of the relative strength of electron-electron interactions that can be lowered with mechanical stress. This result is important for the development of light-emitting devices (LEDs) based on polymers. The work on the effect of electric fields on excitation and exciton kinetics in conducting polymers (Chapter 4) is also important for these kind of LEDs, since high electric fields in a conductive polymer film are necessary for their operation.

Liess, Martin Dieter

234

Wire deconstructionism of two-dimensional topological phases  

NASA Astrophysics Data System (ADS)

A scheme is proposed to construct integer and fractional topological quantum states of fermions in two spatial dimensions. We devise models for such states by coupling wires of nonchiral Luttinger liquids of electrons that are arranged in a periodic array. Which interwire couplings are allowed is dictated by symmetry and the compatibility criterion that they can simultaneously acquire a finite expectation value, opening a spectral gap between the ground state(s) and all excited states in the bulk. First, with these criteria at hand, we reproduce the tenfold classification table of integer topological insulators, where their stability against interactions becomes immediately transparent in the Luttinger liquid description. Second, we construct an example of a strongly interacting fermionic topological phase of matter with short-range entanglement that lies outside of the tenfold classification. Third, we expand the table to long-range entangled topological phases with intrinsic topological order and fractional excitations.

Neupert, Titus; Chamon, Claudio; Mudry, Christopher; Thomale, Ronny

2014-11-01

235

Quantum Hall liquid on a noncommutative superplane  

SciTech Connect

Supersymmetric quantum Hall liquids are constructed on a noncommutative superplane. We explore a supersymmetric formalism of the Landau problem. In the lowest Landau level, there appear spinless bosonic states and spin-1/2 down fermionic states, which exhibit a superchiral property. It is shown that the Laughlin wave function and topological excitations have their superpartners. Similarities between supersymmetric quantum Hall systems and bilayer quantum Hall systems are discussed.

Hasebe, Kazuki [Yukawa Institute for Theoretical Physics, Kyoto University, Kyoto 606-8502 (Japan)

2005-11-15

236

Excitation optimization for damage detection  

SciTech Connect

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.

Bement, Matthew T [Los Alamos National Laboratory; Bewley, Thomas R [UCSD

2009-01-01

237

Effects of dark atom excitations  

NASA Astrophysics Data System (ADS)

New stable quarks and charged leptons may exist and be hidden from detection, as they are bound by Coulomb interaction in neutral dark atoms of composite dark matter. This possibility leads to fundamentally new types of indirect effects related to the excitation of such dark atoms followed by their electromagnetic de-excitation. Stable -2 charged particles O--, bound to primordial helium in O-helium (OHe) atoms, represent the simplest model of dark atoms. Here we consider the structure of OHe atomic levels which is a necessary input for the indirect tests of such composite dark matter scenarios, and we give the spectrum of electromagnetic transitions from the levels excited in OHe collisions.

Cudell, Jean-Rene; Khlopov, Maxim Yu.; Wallemacq, Quentin

2014-11-01

238

Cosmology with liquid mirror telescopes  

NASA Technical Reports Server (NTRS)

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.

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

1993-01-01

239

Liquid Crystal Inquiries.  

ERIC Educational Resources Information Center

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)

Marroum, Renata-Maria

1996-01-01

240

Lacerations - liquid bandage  

MedlinePLUS

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

241

What Is A Liquid?  

NSDL National Science Digital Library

The representation is an animation of the molecular motion of liquid and gaseous bromine. The motion of the atoms of liquid argon and the molecular motion of liquid water are shown as well. Descriptive information accompanies the animation.

242

Waveguide-excited fluorescence microarray  

NASA Astrophysics Data System (ADS)

Signal-to-noise ratio is a crucial issue in microarray fluorescence read-out. Several strategies are proposed for its improvement. First, light collection in conventional microarrays scanners is quite limited. It was recently shown that almost full collection can be achieved in an integrated lens-free biosensor, with labelled species hybridizing practically on the surface of a sensitive silicon detector [L. Martinelli et al. Appl. Phys. Lett. 91, 083901 (2007)]. However, even with such an improvement, the ultimate goal of real-time measurements during hybridization is challenging: the detector is dazzled by the large fluorescence of labelled species in the solution. In the present paper we show that this unwanted signal can effectively be reduced if the excitation light is confined in a waveguide. Moreover, the concentration of excitation light in a waveguide results in a huge signal gain. In our experiment we realized a structure consisting of a high index sol-gel waveguide deposited on a low-index substrate. The fluorescent molecules deposited on the surface of the waveguide were excited by the evanescent part of a wave travelling in the guide. The comparison with free-space excitation schemes confirms a huge gain (by several orders of magnitude) in favour of waveguide-based excitation. An optical guide deposited onto an integrated biosensor thus combines both advantages of ideal light collection and enhanced surface localized excitation without compromising the imaging properties. Modelling predicts a negligible penalty from spatial cross-talk in practical applications. We believe that such a system would bring microarrays to hitherto unattained sensitivities.

Sagarzazu, Gabriel; Bedu, Mlanie; Martinelli, Lucio; Ha, Khoi-Nguyen; Pelletier, Nicolas; Safarov, Viatcheslav I.; Weisbuch, Claude; Gacoin, Thierry; Benisty, Henri

2008-04-01

243

Excitations of Superfluid He4 Beyond the Roton  

NASA Astrophysics Data System (ADS)

Excitations of Superfluid ^4He Beyond the Roton. A. R. SAKHEL and H. R. GLYDE, University of Delaware - We present a Quantum Field Theoretical Model that reproduces the basic features of the temperature dependence of the dynamic structure factor S(Q,?) as observed in the inelastic-neutron scattering results at IRIS, (J.V. Pierce, R.T. Azuah, B.Fk, A.R. Sakhel, H.R. Glyde, and W.G. Stirling, to be published.) UK. The range of the wavevector Q beyond the roton (Q > 2.0is considered. The model is able to simulate the decay of the excitations into two rotons when the excitation energy exceeds 2?, where ? is the roton energy. The model is based on the formulation of S(Q,?) of Gavoret and Nozires.(J. Gavoret and Nozires, Ann. Phys.), 28, 349-399 (1964). The component of dynamic susceptibility involving the condensate is modelled by an equation of the form: \\chis = n n_0(T) ? G ? where ? is a vertex, G the renormalized single particle Green's function, n the density of ^4He at SVP and n_0(T) the condensate fraction as a function of temperature. The dynamic susceptibility involving states above the condensate is modelled by a damped harmonic oscillator function.(H. R. Glyde, Excitation in Liquid and Solid Helium), Oxford, Clarendron Press (1994).

Sakhel, Asaad; Glyde, Henry

2001-03-01

244

Transport currents in Bose quantum liquids  

SciTech Connect

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.

Apaja, V.; Krotscheck, E.; Rimnac, A. [Institut fuer Theoretische Physik, Johannes Kepler Universitaet, A 4040 Linz (Austria); Zillich, R. E. [Fraunhofer ITWM, D-67663 Kaiserslautern (Germany)

2006-09-07

245

Excitation energy transfer between ?-carotene and chlorophyll-a in various systems  

Microsoft Academic Search

The excitation energy transfer from ?-carotene to chlorophyll-a in several seminatural systems such as liposomes, lipid layers and PSI complex has been studied at room and liquid nitrogen temperature. Only in a case of PSI complex an efficient energy transfer (about 30%) from ?-carotene to chlorophyll-a has been observed. The results of energy transfer were discussed on the ground of

G. E. Bia?ek-Bylka; A. Ya. Shkuropatov; S. I. Kadoshnikov; D. Frhckowiak

1982-01-01

246

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

E-print Network

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

Govindjee

247

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

E-print Network

Faraday Discuss., 1997, 108, 115?130 Excited state dynamics in clusters of oxygen Runjun Li, Karl A clusters of oxygen. Oxygen clusters and liquid oxygen have a com- plicated chemistry due to numerous low) dynamics of small anionic clusters of oxygen. We Ðnd that the dynamics of the neutral DPD pathway

Continetti, Robert E.

248

Asymmetric resonant optical torque in azo-dye-doped liquid crystals  

Microsoft Academic Search

The photoexcitation of dichroic azo dyes creates a torque that results in a complex rotational motion of the host molecules in liquid crystal. This phenomenon has asymmetric resonant character. Efficient dynamic holograms are formed on reorientation gratings in the steady-state excitation regime. Orientational order modulation and three-dimensional molecular reorientation are detected in the transient regime of excitation. The complex coupling

Tigran V. Galstian; B. Saad; M. M. Denariez-Roberge

1998-01-01

249

Theory of melted flux liquids  

NASA Astrophysics Data System (ADS)

Novel intermediate flux states should be accessible in high-Tc superconductors, where it appears that the conventional Abrikosov flux lattice is melted over a significant portion of the (H,T) plane. We discuss the Lindemann criterion, and argue that fluctuations in a flux crystal are highly anisotropic, so that an asymptotically two-dimensional melting transition is possible as the shear modulus drops toward zero for many sample geometries and field orientations. We then describe the ``entangled flux liquid'' which arises at high-flux densities or thick samples. The statistical mechanics of this liquid is closely related to the physics of two-dimensional superfluids. The decay of vortex line correlations along the field direction is controlled by the superfluid excitation spectrum. A renormalization-group analysis shows how line wandering changes the nature of the B(H) constitutive relation near Hc1. We suggest that a heavily entangled flux liquid could exhibit a shear modulus on experimental time scales, in analogy with viscoelastic behavior in dense polymer melts.

Nelson, David R.; Seung, H. Sebastian

1989-05-01

250

Communicating the Excitement of Science  

SciTech Connect

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).

Michael Turner

2009-06-05

251

Communicating the Excitement of Science  

ScienceCinema

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).

Michael Turner

2010-01-08

252

Cardiac excitationcontraction coupling  

Microsoft Academic Search

Of the ions involved in the intricate workings of the heart, calcium is considered perhaps the most important. It is crucial to the very process that enables the chambers of the heart to contract and relax, a process called excitationcontraction coupling. It is important to understand in quantitative detail exactly how calcium is moved around the various organelles of the

Donald M. Bers

2002-01-01

253

Perceptual Load Alters Visual Excitability  

ERIC Educational Resources Information Center

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

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

2011-01-01

254

Superheating water by CW excitation of gold nanodots.  

PubMed

A temperature-dependent photoluminescent thin film of Al(0.94)Ga(0.06)N doped with Er(3+) is used to measure the temperature of lithographically prepared gold nanodots. The gold nanodots and thin film are excited simultaneously with a continuous wave (CW) Nd:YAG 532 nm laser. The gold nanodot is submersed under water, and the dot is subsequently heated. The water immediately surrounding the nanodot is 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. PMID:22313363

Carlson, Michael T; Green, Andrew J; Richardson, Hugh H

2012-03-14

255

Liquid annulus  

NASA Technical Reports Server (NTRS)

It is shown that the specific impulse varies with the square root of the temperature and inversely with the square root of the molecular weight of the propellant. Typical values for specific impulse corresponding to various rocket concepts are shown. The Liquid Annulus core concept consists of a fuel element which will be arranged in a moderator block. The advantages as seen for the system are: high specific impulse; structural material will all run at low temperature; and lower fission product inventory because of evaporation. It is felt that this concept is worth at least a first look because of the promise of very high specific impulse. Because of the low thrust, one would probably need a cluster of engines. This is not necessarily bad because there would be some redundancy, but because of the low thrust one might have to refuel while running. Depending on the fuel vaporization, material can be included in the uranium that is injected as one is running along.

Ludewig, Hans

1991-01-01

256

Liquid supercoiling  

NASA Astrophysics Data System (ADS)

Supercoiling is defined as the large-scale secondary coiling of a slender body that is already coiled at a smaller scale (e.g., telephone cords and DNA strands). We demonstrate experimentally a novel fluid-mechanical form of supercoiling that occurs in the context of the familiar ``liquid rope coiling'' instability of a thin thread of viscous fluid falling onto a rigid surface. Under appropriate conditions, the coiling instability generates a tall pile of coils in the form of a hollow cylindrical column, which in turn becomes unstable to a secondary coiling instability with a frequency 10% of the primary one. To place this phenomenon in a broader context, we determine experimentally the phase diagram for the different possible behaviors of the thread (stagnation flow, simple coiling, rotatory folding, periodic column collapse, supercoiling) in the space of the fluid viscosity, the flow rate, and the fall height. We formulate a mathematical model for supercoiling by combining a thin-shell description of the column wall with a slender-thread description of the column as a whole. This leads to a set of coupled ordinary differential equations in one space dimension (the arclength along the axis of the coiling column) that we solve numerically using a continuation method. A comparison of the predicted and observed frequencies of secondary coiling will be shown.

Ribe, Neil; Habibi, Mehdi; Hosseini, Hossein; Hassan Khatami, Mohammad

2011-11-01

257

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

NASA Astrophysics Data System (ADS)

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.

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

1992-06-01

258

Excited states of porphyrin macrocycles.  

PubMed

S1 --> S(n) spectra of porphyrin, diprotonated porphyrin, and tetraoxaporphyrin dication have been measured in the energy range 2-3 eV above S1 at room temperature in solution by means of transient absorption spectroscopy exciting with femtosecond pulses. Highly excited pi pi* states not active in the conventional S0 --> S(n) spectrum have been observed. The experimental data are discussed on the basis of the time dependent density functional theory taking advantage of large scale calculations of configuration interaction between singly excited configurations (DF/SCI). The DF/SCI calculation on porphyrin has allowed to assign g states active in the S1 --> S(n) spectrum. Applying the same calculation method to tetraoxaporphyrin dication the S0 --> S(n) spectrum is reproduced relatively to the Q and B (Soret) bands as well as to the weaker E(u) bands at higher energy. According to our calculation the S1 --> S(n) transient spectrum is related to states of g symmetry mainly arising from excitations between doubly degenerate pi and pi* orbitals such as 2e(g) --> 4e(g). In the case of diprotonated porphyrin it is shown that the complex of the macrocycle with two trifluoroacetate anions plays a significant role for absorption. Charge transfer excitations from the anions to the macrocycle contribute to absorption above the Soret band, justifying the intensity enhancement of the S0 --> S(n) spectrum with respect to the other two macrocyclic systems. PMID:18855369

Moroni, Laura; Gellini, Cristina; Salvi, Pier Remigio; Marcelli, Agnese; Foggi, Paolo

2008-11-01

259

Electrokinetics over liquid/liquid interfaces  

NASA Astrophysics Data System (ADS)

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

Squires, Todd M.

2011-11-01

260

Traveling Through Different Liquids  

NSDL National Science Digital Library

Learners observe and record what happens when they manipulate bottles containing a liquid (water or corn syrup) and one or more objects (screw, nail, paper clip). They should observe differences in how quickly the objects fall in the different liquids. This lesson builds on what learners have studied in previous lessons, Exploring Liquids and Exploring How Liquids Behave.

Janulaw, Sharon

2010-01-01

261

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.

262

Look-alike Liquids  

NSDL National Science Digital Library

Learners add drops of four liquids (water, alcohol, salt water, and detergent solution) to different surfaces and observe the liquids' behavior. Learners will see that liquids have characteristic properties which can be used for identification. In the related activity, " Developing Tests to Distinguish Between Similar-Looking Liquids" (see related resources), learners identify an unknown based on these properties.

James H. Kessler

2007-01-01

263

Directable photorealistic liquids  

Microsoft Academic Search

We present a method for the directable animation of photorealistic liquids using the particle level set method to obtain smooth, visually pleasing complex liquid surfaces. We also provide for a degree of control common to particle-only based simulation techniques. A variety of directable liquid primitive variables, including the isosurface value, velocity, and viscosity, can be set throughout the liquid. Interaction

N. Rasmussen; D. Enright; D. Nguyen; S. Marino; N. Sumner; W. Geiger; S. Hoon; R. Fedkiw

2004-01-01

264

Plasma-liquid system with rotational gliding arc with liquid electrode  

NASA Astrophysics Data System (ADS)

Atmospheric pressure plasmas can be created by various types of discharges: transverse arc; discharge in gas channel with liquid wall and others. But most of them aren't sufficiently stable. Stabilization of discharge in the high pressure powerful plasmatron is attained by vortex flow of gas. In the low-powered high pressure discharges the reverse vortex flow ``tornado'' type can be used for the space stabilization. The voltage-current characteristics of discharge at the different regimes are measured. Typical emission spectra of plasma in plasma-liquid system with rotational gliding arc were measured. The population temperatures of excited electronic, vibrational, rotational levels and the flame temperature are determined.

Nedybaliuk, Oleg; Chernyak, Valeriy; Martysh, Eugene; Belenok, Natalia; Lisitchenko, Tamara

2012-10-01

265

Vibration effects of the dynamic interaction between a gas-liquid medium and elastic shells  

Microsoft Academic Search

The paper presents the results of experimental investigations of regimes of the nonlinear deformation of elastic shells filled\\u000a with a liquid. These regimes are due to the interaction of local clusters of gas bubbles formed in a vibrating liquid with\\u000a the vibration modes of an elastic shell excited in the circumferential and longitudinal directions.

V. D. Kubenko; V. D. Lakiza

2000-01-01

266

Optic mode determination of the relaxed state configuration in a ferroelectric liquid crystal cell  

Microsoft Academic Search

Here the method of propagation of optic modes to examine the alignment in a ferroelectric liquid crystal layer is fully discussed. A sample geometry which allows the excitation of optic modes in a ferroelectric liquid crystal cell is presented and the data obtained in terms of reflectivity. The data are analysed by modelling the expected reflectivity from such a cell

S. J. Elston

1991-01-01

267

Exploring How Liquids Behave  

NSDL National Science Digital Library

Learners apply their knowledge from a previous study to identify different liquids--water, corn syrup, and vegetable oil. They also investigate combinations of liquids, two at a time, to see how they interact. This is meant as a follow-up lesson to the related activity, Exploring Liquids. As an extension, learners can continue their study of these liquids in the lesson, Traveling Through Different Liquids.

Janulaw, Sharon

2010-01-01

268

Autoresonant excitation of dark solitons.  

PubMed

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

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

2015-01-01

269

Dipole excitations in 96Ru  

NASA Astrophysics Data System (ADS)

Candidates for the two-phonon quadrupole-octupole 1- state and the two-phonon mixed-symmetry 1+ms state have been identified in the N=52 isotope 96Ru using the nuclear resonance fluorescence technique at the bremsstrahlung facility of the Stuttgart Dynamitron accelerator. Detailed information on energies, spins, branching ratios, and transition strengths of four new dipole excitations in 96Ru have been obtained. The observed dipole excitations are nearly at the same energies as in 94Mo, and the transition probabilities are comparable to those for the decay of the (2+1?3-1)1- and the (2+1?2+ms)1+ms states in 94Mo.

Linnemann, A.; Fransen, C.; Gorska, M.; Jolie, J.; Kneissl, U.; Knoch, P.; Mcher, D.; Pitz, H. H.; Scheck, M.; Scholl, C.; Brentano, P. Von

2005-12-01

270

Spatiotemporal control of nanooptical excitations  

PubMed Central

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

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

2010-01-01

271

Multiphoton-Excited Serotonin Photochemistry  

PubMed Central

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

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

2004-01-01

272

Receiver-exciter controller design  

NASA Astrophysics Data System (ADS)

A description of the general design of both the block 3 and block 4 receiver-exciter controllers for the Deep Space Network (DSN) Mark IV-A System is presented along with the design approach. The controllers are designed to enable the receiver-exciter subsystem (RCV) to be configured, calibrated, initialized and operated from a central location via high level instructions. The RECs are designed to be operated under the control of the DMC subsystem. The instructions are in the form of standard subsystem blocks (SSBs) received via the local area network (LAN). The centralized control provided by RECs and other DSCC controllers in Mark IV-A is intended to reduce DSN operations costs from the Mark III era.

Jansma, P. A.

1982-06-01

273

Receiver-exciter controller design  

NASA Technical Reports Server (NTRS)

A description of the general design of both the block 3 and block 4 receiver-exciter controllers for the Deep Space Network (DSN) Mark IV-A System is presented along with the design approach. The controllers are designed to enable the receiver-exciter subsystem (RCV) to be configured, calibrated, initialized and operated from a central location via high level instructions. The RECs are designed to be operated under the control of the DMC subsystem. The instructions are in the form of standard subsystem blocks (SSBs) received via the local area network (LAN). The centralized control provided by RECs and other DSCC controllers in Mark IV-A is intended to reduce DSN operations costs from the Mark III era.

Jansma, P. A.

1982-01-01

274

Singleparticle excitations in 89Y  

Microsoft Academic Search

Inelastic-electron-scattering cross sections have been measured for the first three excitations in 89Y at forward angles for momentum transfers of 1.25

J. E. Wise; F. W. Hersman; J. H. Heisenberg; T. E. Milliman; J. P. Connelly; J. R. Calarco; C. N. Papanicolas

1990-01-01

275

Wedding ring shaped excitation coil  

DOEpatents

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.

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

2001-01-01

276

Accurate electromagnetic modeling of liquid crystal cells for reconfigurable reflectarrays  

Microsoft Academic Search

An electromagnetic modeling has been presented for an accurate analysis of reconfigurable reflectarray cells based on liquid crystals (LC). The proposed modeling considers both the inhomogeneity and anisotropic effects, which are calculated by using a simplified molecular model for the behavior of the LC when it is excited by an electrostatic field. The inhomogeneity of the LC is analyzed by

G. Perez-Palomino; J. A. Encinar; M. Barba

2011-01-01

277

Hydrodynamic pressure in a tank containing two liquids  

Microsoft Academic Search

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

1992-01-01

278

Low-frequency in stability in liquid - propellant rocket motors  

Microsoft Academic Search

A detailed analysis of the simultaneous action Of both excitation mechanisms was given in monograph [4]. Analysis of the stability of operation of a rocket motor, allowing for compressibility of the liquid in the feed line, for the simplest monopropellant system, shows that the critical delay time depends on the length of the line and decreases with the increase in

K. S. Kolesnikov

1965-01-01

279

Soliton gating and switching in liquid crystal light valve  

NASA Astrophysics Data System (ADS)

Using a photoconductive light valve with nematic liquid crystals, we introduce a versatile platform for the excitation and routing of spatial optical solitons, with external beams controlling the whereabouts of the underlying all-optically induced waveguides and their spatial dynamics. Using this all-optical control of soliton trajectory, we demonstrate a NOR gate, an XNOR, and a Boolean half-adder.

Piccardi, Armando; Alberucci, Alessandro; Bortolozzo, Umberto; Residori, Stefania; Assanto, Gaetano

2010-02-01

280

Laser excitation of high-frequency capillary waves.  

PubMed

The laser-induced surface deformation (LISD) technique was applied to generate high-frequency capillary waves on liquid surfaces up to several tens of kHz in a noncontact manner. The dynamic response of the fluid near the surface was theoretically derived under the condition of periodical radiation pressure. The result of the numerical calculation predicts the propagation of induced capillary waves out from the excitation region. The efficiency of the wave generation was experimentally examined by changing the width of the excitation laser beam at the surface. The observed LISD spectra were well reproduced by the theory, showing that the effective frequency band can be extended up to over 100 kHz. The propagation of the optically generated wave was measured with a laser probe sweeping the position of the observation. The spatial profile gives the surface tension and the shear viscosity of the sample liquid. The frequency domain measurement was also carried out and the spectrum obtained at a fixed point agrees with the theory, demonstrating the rapid measurement of frequency-dependent phenomena. PMID:16256663

Sakai, K; Tachibana, K; Mitani, S; Takagi, K

2003-08-15

281

Current algebras and liquid helium  

NASA Astrophysics Data System (ADS)

Several theories for elementary excitations in liquid 4He are examined within the formalism of the nonrelativistic current algebra. We make use of the Helmholtz decomposition for the current operator, and an appropriate collective approximation to the algebra. The Bogoliubov spectrum is obtained, as has been done previously. An appropriate rescaling of the phonon operators then yields the Landau condition for superfluid flow. The transverse part of the Hamiltonian yields the Hamiltonian for vortex-vortex interactions in three dimensions. Examination of the current operators under the Helmholtz decomposition yields the operators describing a quantum vortex, first given by Rasetti and Regge, and their theory follows directly. Further examination of the smeared operators yields the roton theory of Feynman and Feynman and Cohen, which we modify using the Helmholtz decomposition.

Albertin, Uwe K.; Morrison, Harry L.

1989-08-01

282

Mass transfer enhancement by gravity waves at a liquidvapour interface  

Microsoft Academic Search

Experimental results on mass transfer enhancement by large amplitude gravity waves at a liquidgas\\/vapour interface are presented. The waves are sub-harmonically excited in a circular cylinder that is partially filled with liquid, by oscillating the cylinder in the direction normal to the liquid surface. The lowest asymmetric sloshing mode (1,1) as well as the axisymmetric mode (0,1) are considered in

S. P. Das; E. J. Hopfinger

2009-01-01

283

46 CFR 111.12-3 - Excitation.  

...In particular, no static exciter may be used for excitation of an emergency generator unless it is provided with a permanent magnet or a residual-magnetism-type exciter that has the capability of voltage build-up after two months of no operation....

2014-10-01

284

Search for excited neutrinos in Z decay  

Microsoft Academic Search

Excited neutrinos decaying into a neutrino and a photon are searched for in the ALEPH detector at LEP. No evidence is found for Z decay into vv* or v*v* final states. Upper limits are derived on excited neutrino couplings up to excited neutrino masses close to the Z mass. Lower limits on the v* mass, independent of the v* decay

D. Decamp; B. Deschizeaux; C. Goy; J.-P. Lees; M.-N. Minard; R. Alemany; J. M. Crespo; M C Delfino; E. Fernandez; V. Gaitan; Ll. Garrido; P. Mato; R. Miguel; Ll. M. Mir; S. Orteu; A. Pacheco; J. A. Perlas; E. Tubau; M. G. Catanesi; D. Creanza; M. de Palma; A. Farilla; G. Iaselli; G. Maggi; M. Maggi; S. Natali; S. Nuzzo; M. Quattromini; A. Ranieri; G. Raso; F Ruggieri; G. Selvaggi; L. Silvestris; P. Tempesta; G. Zito; Y. S. Gao; H. Hu; D. Huang; S. Jin; J. Lin; T. Ruan; T. Wang; W. Wu; Y. Xie; D. Xu; R. Xu; J. Zhang; W. Zhao; W. B. Atwood; F. Bird; E. Blucher; G. Bonvicini; F. Bossi; J. Bourotte; D. Brown; T. H. Burnett; H. Drevermann; Friedrich Dydak; R. W. Forty; C. Grab; R. Hagelberg; S. Haywood; B. Jost; M. Kasemann; G. Kellner; J. Knobloch; A. Lacourt; I. Lehraus; T. Lohse; A. Marchioro; M. Martinez; S. Menary; A. Minten; A. Miotto; J. Nash; P. Palazzi; F. Ranjard; G. Redlinger; A. Roth; J. Rothberg; H. Rotscheidt; W. von Rden; R. St. Denis; D. Schlatter; M. Takashima; M. Talby; H. Taureg; W. Tejessy; H. Wachsmuth; S. Wasserbaech; S. Wheeler; W. Wiedenmann; W. Witzeling; J. Wotschack; Z. Ajaltouni; M. Bardadin-Otwinowska; A. Falvard; R. El Fellous; P. Gay; P. Henrard; J. Jousset; B. Michel; J.-C. Montret; D. Pallin; P. Perret; J. Proriol; F. Prulhire; J. D. Hansen; J. R. Hansen; P. H. Hansen; R. Mllerud; B. S. Nilsson; G. Petersen; I. Efthymiopoulos; E. Simopoulou; A. Vayaki; J. Badier; A. Blondel; G. Bonneaud; F. Braems; J. C. Brient; G. Fouque; A. Gamess; R. Guirlet; A. Rosowsky; A. Roug; M. Rumpf; R. Tanaka; H. Videau; I. Videau; D. J. Candlin; G. Parrini; M. Corden; C. Georgiopoulos; M. Ikeda; J. Lannutti; D. Levinthal; M. Mermikides; L. Sawyer; G. Stimpfl; A. Antonelli; R. Baldini; G. Bencivenni; G. Bologna; P. Campana; G. Capon; V. Chiarella; B. D'Ettorre-Piazzoli; G. Felici; P. Laurelli; G. Mannocchi; F. Massimo-Brancacci; F. Murtas; G. P. Murtas; G. Nicoletti; M. Pepe-Altarelli; P. Picchi; P. Zografou; B. Altoon; O. Boyle; A. W. Halley; I. Ten Have; J. L. Hearns; J. G. Lynch; W. T. Morton; C. Raine; J. M. Scarr; K. Smith; A. S. Thompson; B. Brandl; O. Braun; R. Geiges; C. Geweniger; P. Hanke; V. Hepp; E. E. Kluge; Y. Maumary; A. Putzer; B. Rensch; A. Stahl; K. Tittel; M. Wunsch; A. T. Belk; R. Beuselinck; D. M. Binnie; W. Cameron; M. Cattaneo; P. J. Dornan; S. Dugeay; A. M. Greene; J. F. Hassard; S. J. Patton; J. K. Sedgbeer; G. Taylor; I. R. Tomalin; A. G. Wright; P. Girtler; D. Kuhn; G. Rudolph; C. K. Bowdery; T. J. Brodbeck; A. J. Finch; F. Foster; G. Hughes; N. R. Keemer; M. Nuttall; B. S. Rowlingson; T. Sloan; S. W. Snow; T. Barczewski; L. A. T. Bauerdick; K. Kleinknecht; B. Renk; S. Roehn; H.-G. Sander; M. Schmelling; F. Steeg; J.-P. Albanese; J.-J. Aubert; C. Benchouk; V. Bernard; A. Bonissent; D. Courvoisier; F. Etienne; S. Papalexiou; P. Payre; B. Pietrzyk; Z. Qian; W. Blum; P. Cattaneo; G. Cowan; B. Dehning; H. Dietl; M. Fernandez-Bosman; A. Jahn; E. Lange; G. Ltjens; G. Lutz; W. Mnner; H.-G. Moser; Y. Pan; R. Richter; A. S. Schwarz; R. Settles; U. Stiegler; U. Stierlin; J. Thomas; V. Bertin; G. de Bouard; J. Boucrot; O. Callot; X. Chen; A. Cordier; M. Davier; G. Ganis; J.-F. Grivaz; Ph. Heusse; P. Janot; V. Journ; D. W. Kim; J. Lefranois; A.-M. Lutz; J.-J. Veillet; Z. Zhang; F. Zomer; S. R. Amendolia; G. Bagliesi; G. Batignani; L. Bosisio; U. Bottigli; C. Bradaschia; M. A. Ciocci; I. Ferrante; F. Fidecaro; L. Fo; E. Focardi; F. Forti; A. Giassi; M. A. Giorgi; F. Ligabue; A. Lusiani; E. B. Mannelli; P. S. Marrocchesi; A. Messineo; F. Palla; G. Sanguinetti; J. Steinberger; R. Tenchini; G Triggiani; J. M. Carter; M. G. Green; P. V. March; T. Medcalf; M. R. Saich; J. A. Strong; R. M. Thomas; T. Wildish; D. R. Botterill; R. W. Clifft; T. R. Edgecock; M. Edwards; S. M. Fisher; J. Harvey; T. J. Jones; P. R. Norton; D. P. Salmon; J. C. Thompson; B. Bloch-Devaux; P. Colas; C. Klopfenstein; E. Lanon; E. Locci; S. Loucatos; L. Mirabito; E. Monnier; P. Perez; F. Perrier; J. Rander; J.-F. Renardy; A. Roussarie; J.-P. Schuller; J. G. Ashman; C. N. Booth; F. Combley; M. Dinsdale; J. Martin; D. Parker; L. F. Thompson; S. Brandt; H. Burkhardt; C. Grupen; H. Meinhard; E. Neugebauer; U. Schfer; H. Seywerd; G. Apollinari; G. Giannini; B. Gobbo; F. Liello; E. Milotti; L. Rolandi; L. Bellantoni; J. F. Boudreau; D. Cinabro; J. S. Conway; D. F. Cowen; A. J. Deweerd; Z. Feng; D. P. S. Ferguson; J. L. Harton; J. Hilgart; J. E. Jacobsen; R. C. Jared; R. P. Johnson; B. W. Leclaire; T. Parker; J. R. Pater; Y. Saadi; V. Sharma; J. A. Wear; F. V. Weber; Sau Lan Wu; G. Zobernig

1990-01-01

285

Slosh wave excitation in a partially filled rotating tank due to gravity jitters in a microgravity environment  

NASA Technical Reports Server (NTRS)

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 tank without probe imposed by various frequencies of gravity jitters have been investigated. Twelve case studies of slosh wave excitation due to various frequencies of gravity jitters under different rotating speeds of propellant tank and different levels of background gravity environment have been numerically simulated. Results disclose the conditions for the excitation of large amplitude slosh waves which shall be avoided in the design of cryogenic liquid propellant system.

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

1991-01-01

286

Slosh wave excitation in a partially filled rotating tank due to gravity jitters in a microgravity environment  

NASA Astrophysics Data System (ADS)

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 tank without probe imposed by various frequencies of gravity jitters have been investigated. Twelve case studies of slosh wave excitation due to various frequencies of gravity jitters under different rotating speeds of propellant tank and different levels of background gravity environment have been numerically simulated. Results disclose the conditions for the excitation of large amplitude slosh waves which shall be avoided in the design of cryogenic liquid propellant system.

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

287

Giant Thermomagnetic Effects in High-Tc Cuprates: Fermi Liquid vs Vortex Liquid  

NASA Astrophysics Data System (ADS)

We developed a gauge-invariant formulation of the thermomagnetic effects [1] and prove that the thermomagnetic coefficients in the Fermi liquid with particle and hole excitations are always proportional to the square of the particle-hole asymmetry. Therefore, thermomagnetic effects in the Fermi liquid are always small. Vortices are topological excitations which are completely different from particle-hole excitations. Thermomagnetic transport in the vortex liquid is widely described in terms of the ``transport entropy,'' Sd. According to the current views, the main contribution to Sd originates from the electromagnetic energy of superconducting currents circulating around vortex cores. However, this concept strongly contradicts to the London postulate [2]. We revise the theory and show that the transport entropy is, in fact, the entropy of normal electrons in vortex cores determined with respect to the superconducting (or partly superconducting, if cores overlap) background [2]. Only in this form the theory becomes simultaneously consistent with the London postulate and Onsager principle. The theory naturally explains the observed temperature dependence of Sd. 1. A. Sergeev et al., Phys. Rev. B 77 064501 (2008). 2. A. Sergeev et al., arXiv:0807.0450.

Sergeev, Andrei; Reizer, Michael; Mitin, Vladimir

2009-03-01

288

Molecular dynamics simulations of chemical reactions at liquid/vapor and liquid/liquid interfaces  

NASA Astrophysics Data System (ADS)

The photodissociation of ICN in water and at the water liquid/vapor interface is studied using mixed quantum-classical molecular dynamics simulations. A water-ICN potential energy function that takes into account the different ground and excited state charges and their shift as a function of the reaction coordinate is developed. The calculations include non-adiabatic transitions between electronic states. In the bulk, the calculated absorption spectrum, cage escape probability, quantum yield of ICN and INC, and the subsequent vibrational relaxation rate are in reasonable agreement with experiments. At the interface, the reduced surface density and weaker solvent-solute interactions give rise to a reduced rate of nonadiabatic transitions and the probability for cage escape is enhanced. The overall desorption probability varies from 75% to 92% for ICN initially located just below the Gibbs surface to ICN located just above the Gibbs surface, respectively. The corresponding geminate recombination probabilities are 18% and 9% respectively (compared to 85% in the bulk). The vibrational relaxation rate of the recombined ICN is slower than in the bulk by a factor of 2.3. The thermodynamics and dynamics of a model SN1 reaction: t-BuCl ? t-Bu+ + Cl- is studied at the water liquid/vapor interface, and the water/CCl 4 and water/DCE liquid/liquid interfaces using mixed quantum-classical molecular dynamics computer simulations. The empirical valence bond approach is used to couple two diabatic states, covalent and ionic, in the electronically adiabatic limit. Umbrella sampling calculations are used to calculate the potential of mean force along the reaction coordinate (defined as the t-Bu to Cl distance) in bulk water and at the interface. We find a significant increase of the dissociation barrier height and of the reaction free energy at the interface relative to the bulk. This is shown to be due to the reduced polarity of the interface which causes destabilization of the ionic state. At the water/organic liquid/liquid interface deformation to the neat interface structure in the form of water protrusions into the organic phase may provide partial stabilization of the ionic species. Reactive flux correlation function calculations show significant deviation of the rate constant from transition-state theory.

Winter, Nicolas D.

289

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

SciTech Connect

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.

Gerasimov, V. A. [Institute of Atmospheric Optics, Siberian Branch of the Russian Academy of Sciences, Tomsk, 634055 (Russian Federation); Gerasimov, V. V. [Institute of Atmospheric Optics, Siberian Branch of the Russian Academy of Sciences, Tomsk, 634055 (Russian Federation); Department of Physics, Tomsk State University, Tomsk, 634050 (Russian Federation); Pavlinskiy, A. V. [Institute of High Current Electronics, Siberian Branch of the Russian Academy of Sciences, Tomsk, 634055 (Russian Federation)

2007-09-15

290

Liquid level detector  

DOEpatents

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.

Grasso, A.P.

1984-02-21

291

Liquid level detector  

DOEpatents

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.

Grasso, Albert P. (Vernon, CT)

1986-01-01

292

Semiconductor nanorod liquid crystals  

SciTech Connect

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

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

2002-01-28

293

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

NASA Astrophysics Data System (ADS)

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.

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

1992-08-01

294

Inwardly rotating spirals in nonuniform excitable media.  

PubMed

Inwardly rotating spirals (IRSs) have attracted great attention since their observation in an oscillatory reaction-diffusion system. However, IRSs have not yet been reported in planar excitable media. In the present work we investigate rotating waves in a nonuniform excitable medium, consisting of an inner disk part surrounded by an outer ring part with different excitabilities, by numerical simulations of a simple FitzHugh-Nagumo model. Depending on the excitability of the medium as well as the inhomogeneity, we find the occurrence of IRSs, of which the excitation propagates inwardly to the geometrical spiral tip. PMID:22400649

Gao, Xiang; Feng, Xia; Cai, Mei-chun; Li, Bing-wei; Ying, He-ping; Zhang, Hong

2012-01-01

295

Charge transfer reactions in nematic liquid crystals  

SciTech Connect

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.

Wiederrecht, G.P. [Argonne National Lab., IL (United States). Chemistry Div.; Wasielewski, M.R. [Argonne National Lab., IL (United States). Chemistry Div.; [Northwestern Univ., Evanston, IL (United States). Dept. of Chemistry; Galili, T.; Levanon, H. [Hebrew Univ. of Jerusalem (Israel). Dept. of Physical Chemistry

1998-07-01

296

Turbulent swirling jets with excitation  

NASA Technical Reports Server (NTRS)

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.

Taghavi, Rahmat; Farokhi, Saeed

1988-01-01

297

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

NASA Astrophysics Data System (ADS)

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

Yoshiki, Keisuke; Hashimoto, Mamoru; Araki, Tsutomu

2005-08-01

298

Electron beam excitation of surface plasmon polaritons.  

PubMed

In this paper, the excitations of surface plasmon polaritons (SPPs) by both perpendicular and parallel electron beam are investigated. The results of analytical theory and numerical calculation show that the mechanisms of these two excitations are essentially different, and the behavior and properties of SPPs in metal structures strongly depend on the methods of excitation. For the perpendicular excitation, SPPs contain plenty of frequency components, propagate with attenuation and are always accompanied with the transition radiation. Whereas for parallel excitation, SPPs waves are coherent, tunable, propagating without attenuation and the transition radiation does not occur. We also show that there are two modes for the parallel excited SPPs on the metal films and they all can be excited efficiently by the parallel moving electron beam. And the operating frequency of SPPs can be tuned in a large frequency range by adjusting the beam energy. PMID:25321010

Gong, Sen; Hu, Min; Zhong, Renbin; Chen, Xiaoxing; Zhang, Ping; Zhao, Tao; Liu, Shenggang

2014-08-11

299

Collective excitations in the continuum  

SciTech Connect

Pairing (particle-particle) giant resonances are analyzed within a shell-model formalism in the complex energy plane with the aim of understanding why they have not been observed so far. A comparison is made with the equivalent particle-hole mode by applying the formalism to the analysis of the well-understood particle-hole giant resonance. It is found that because of the proper treatment of the continuum intrinsic to the formalism, giant pairing resonances lie much higher than previously predicted and that some of them may be too wide to be observed, whereas others are meaningful excitations. For these, new experimental searches are proposed.

Dussel, G. G. [Departamento de Fisica, FCEyN-UBA, Ciudad Universitaria, 1428 Buenos Aires (Argentina); Betan, R. Id [Departamento de Quimica y Fisica, FCEIA (UNR)-Instituto de Fisica Rosario, IFIR (CONICET), 2000 Rosario (Argentina); Liotta, R. J. [KTH, Alba Nova University Center, S-10691 Stockholm (Sweden); Vertse, T. [Institute of Nuclear Research of the Hungarian Academy of Sciences, H-4001 Debrecen (Hungary); Faculty of Informatics, University of Debrecen, H-4010 Debrecen (Hungary)

2009-12-15

300

High Frequency Chandler Wobble Excitation  

NASA Astrophysics Data System (ADS)

Variations of Earth rotation on sub-daily to secular timescales are caused by mass redistributions in the Earth system as a consequence of geophysical processes and gravitational influences. Forced oscillations of polar motion are superposed by free oscillations of the Earth, i.e. the Chandler wobble and the free core nutation. In order to study the interactions between externally induced polar motion and the Earth's free oscillations, a non-linear gyroscopic model has been developed. In most of the former investigations on polar motion, the Chandler wobble is introduced as a damped oscillation with predetermined frequency and amplitude. However, as the effect of rotational deformation is a backcoupling mechanism of polar motion on the Earth's rotational dynamics, both period and amplitude of the Chandler wobble are time-dependent when regarding additional excitations from, e.g., atmospheric or oceanic mass redistributions. The gyroscopic model is free of any explicit information concerning amplitude, phase, and period of free oscillations. The characteristics of the Earth's free oscillation is reproduced by the model from rheological and geometrical parameters and rotational deformation is taken into account. This enables to study the time variable Chandler oscillation when the gyro is forced with atmospheric and oceanic angular momentum from the global atmospheric ECHAM3-T21 general circulation model together with the ocean model for circulation and tides OMCT driven by ECHAM including surface pressure. Besides, mass redistributions in the Earth's body due to gravitational and loading deformations are regarded and external torques exerted by Moon and Sun are considered. The numerical results of the gyro are significantly related with the geodetically observed time series of polar motion published by the IERS. It is shown that the consistent excitation is capable to counteract the damping and thus to maintain the Chandler amplitude. Spectral analyses of the ECHAM and OMCT forcing fields give no hint for increased excitation power in the Chandler band. Thus it is assumed, that continuous high frequency excitation due to stochastic weather phenomena is responsible for the perpetuation of the Chandler wobble.

Seitz, F.; Stuck, J.; Thomas, M.

2003-04-01

301

Dynamics of liquid-liquid displacement.  

PubMed

Capillary driven liquid-liquid displacement in a system with two immiscible liquids of comparable viscosity was investigated by means of optical high speed video microscopy. For the first time, the impact of substrate wettability on contact line dynamics in liquid-liquid systems was studied. On all substrates, qualitatively different dynamics, in two distinct velocity regimes, were found. Hydrodynamic models apply to the fast stage of initial spreading, while nonhydrodynamic dissipation dominates contact line motion in a final stage at low speed, where the molecular kinetic theory (MKT) successfully captured the dynamics. The MKT model parameter values showed no systematic dependence on substrate wettability. This unexpected result is interpreted in terms of local contact line pinning. PMID:19496572

Fetzer, Renate; Ramiasa, Melanie; Ralston, John

2009-07-21

302

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

NASA Astrophysics Data System (ADS)

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.

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

1991-10-01

303

Rock drilling, cooling liquids  

NSF Publications Database

Title : Rock drilling, cooling liquids Type : Antarctic EAM NSF Org: OD / OPP Date : October 23 ... impacts that could accrue from the use of cooling liquids during rock drilling. Our discussion of ...

304

Zero gravity liquid mixer  

NASA Technical Reports Server (NTRS)

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.

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

1973-01-01

305

Liquid seeding atomizer  

NASA Technical Reports Server (NTRS)

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.

Seegmiller, Henry L. B. (inventor)

1987-01-01

306

Excitations of Superfluid ^4He at Wavevectors Beyond the Roton  

NASA Astrophysics Data System (ADS)

We present a Quantum Field Theoretical Model that reproduces the basic features of the temperature dependence of the dynamic structure factor S(Q,?) of ^4He as observed in the inelastic-neutron scattering data taken at ISIS( J. V. Pierce, R. T. Azuah, B. F, A. R. Sakhel, H. R. Glyde, W. G. Stirling, J. Phys: Cond. Matter, 13(2001) 4421., UK. A range of the wavevectors Q beyond the roton (Q > 2.0 is considered. The model is able to reproduce the decrease in the intensity of the single-particle excitation peak with increase of T in the range 0.6 <= T <= 2.1 K. Also, it reproduces the second peak at higher energy representing the single excitation intensity lying in the two excitation band. The model is based on the formulation of S(Q,?) of Gavoret and Nozires( J. Gavoret and P. Nozires, Ann. Phys., 28, 349-399 (1964). In this formulation, the dynamic susceptibility is separated into a singular part involving the condensate and a regular part involving states above the condensate \\chi = \\chiS + \\chi_R. Here \\chiS = n n_0(T) ? G ?, ? is a vertex, G the renormalized single particle Green's function, n the density of ^4He at SVP and n_0(T) the condensate fraction as a function of T. \\chi_R(Q,?) involves both a single particle-hole and a multiparticle component. All vertices and interactions are assumed T-independent, and only n0 changes with T. Also, the roton width is accounted for by a momentum (k) and temperature dependent width of the Landau-Khalatnikov form (H. R. Glyde, Excitations in Liquid and Solid helium), Oxford, Clarendron Press, (1994)..

Glyde, Henry; Sakhel, Asaad

2002-03-01

307

Thermal conductivity of liquids  

Microsoft Academic Search

The Bridgman equation for thermal conductivity of liquids is examined and a relation between sonic velocity and latent heat of vaporization is given. A correlation based on the hole theory of liquids is presented. This correlation predicts thermal conductivity in the temperature range of -20° to +80°C for 16 liquids, and at 20°C for 50 liquids with an average absolute

D. S. Viswanath

1967-01-01

308

Liquid level sensing device  

DOEpatents

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.

Tokarz, Richard D. (West Richland, WA)

1983-01-01

309

Coulomb excitation of 73Ga  

E-print Network

The B(E2; Ii -> If) values for transitions in 71Ga and 73Ga were deduced from a Coulomb excitation experiment at the safe energy of 2.95 MeV/nucleon using post-accelerated beams of 71,73Ga at the REX-ISOLDE on-line isotope mass separator facility. The emitted gamma rays were detected by the MINIBALL-detector array and B(E2; Ii->If) values were obtained from the yields normalized to the known strength of the 2+ -> 0+ transition in the 120Sn target. The comparison of these new results with the data of less neutron-rich gallium isotopes shows a shift of the E2 collectivity towards lower excitation energy when adding neutrons beyond N = 40. This supports conclusions from previous studies of the gallium isotopes which indicated a structural change in this isotopical chain between N = 40 and N = 42. Combined with recent measurements from collinear laser spectroscopy showing a 1/2- spin and parity for the ground state, the extracted results revealed evidence for a 1/2-; 3/2- doublet near the ground state in 73 31Ga42 differing by at most 0.8 keV in energy.

J. Diriken; I. Stefanescu; D. Balabanski; N. Blasi; A. Blazhev; N. Bree; J. Cederkll; T. E. Cocolios; T. Davinson; J. Eberth; A. Ekstrm; D. V. Fedorov; V. N. Fedosseev; L. M. Fraile; S. Franchoo; G. Georgiev; K. Gladnishki; M. Huyse; O. V. Ivanov; V. S. Ivanov; J. Iwanicki; J. Jolie; T. Konstantinopoulos; Th. Krll; R. Krcken; U. Kster; A. Lagoyannis; G. Lo Bianco; P. Maierbeck; B. A. Marsh; P. Napiorkowski; N. Patronis; D. Pauwels; P. Reiter; M. Seliverstov; G. Sletten; J. Van de Walle; P. Van Duppen; D. Voulot; W. B. Walters; N. Warr; F. Wenander; K. Wrzosek

2010-10-13

310

Fluid Mechanics of Liquid-Liquid Systems.  

NASA Astrophysics Data System (ADS)

The detailed hydrodynamics of selected liquid -liquid flow systems are investigated to provide a firm foundation for the rational design of separation processes. The implementation of this objective centers on the development of a robust code to simulate liquid-liquid flows. We have applied this code to the realistic simulation of aspects of the complex fluid mechanical behavior, and developed quantitative insight into the underlying processes involved. The Volume of Fluid (VOF) method is combined with the Continuous Surface Force (CSF) algorithm to provide a numerically stable code capable of solving high Reynolds numbers free surface flows. One of the developments during the testing was an efficient method for solving the Young-Laplace equation describing the shape of the meniscus in a vertical cylinder for a constrained liquid volume. The steady-state region near the nozzle for the laminar flow of a Newtonian liquid jet injected vertically into another immiscible Newtonian liquid is investigated for various Reynolds numbers by solving the axisymmetric transient equations of motion and continuity. The analysis takes into account pressure, viscous, inertial, gravitational, and surface tension forces, and comparison with previous experimental measurements shows good agreement. Comparisons of the present numerical method with the numerical results of previous boundary-layer methods help establish their range of validity. A new approximate equation for the shape of the interface of the steady jet, based on an overall momentum balance, is also developed. The full transient from liquid-liquid jet startup to breakup into drops is also simulated numerically. In comparison with experiment, the results of the present numerical method show a greater sensitivity of the jet length to the Reynolds number than the best predictions of previous linear stability analyses. The formation of drops is investigated at low to high Reynolds numbers before and after jet formation. The numerical simulations are satisfactorily compared with n-heptane/water experiments and previous simplified analyses based on drop formation before and after jetting. Although the program and numerical techniques developed in this dissertation have been used mainly to solve problems involving liquid-liquid jets and drops, many features of more complex and general liquid-liquid contacting systems are explored in the process.

Richards, John Reed

311

Mixtures of ionic liquids.  

PubMed

Simple ionic liquids have long been held to be designer solvents, based upon the ability to independently vary their cations and anions. The formation of mixtures of ionic liquids increases this synthetic flexibility. We review the available literature of these ionic liquid mixtures to identify how their properties change and the possibility for their application. PMID:22890419

Niedermeyer, Heiko; Hallett, Jason P; Villar-Garcia, Ignacio J; Hunt, Patricia A; Welton, Tom

2012-12-01

312

Tunable liquid crystal lasers  

Microsoft Academic Search

Liquid crystal lasers are dye-doped distributed feedback lasing systems. Fabricated by coupling the periodic structure of a liquid crystal medium with a fluorescent dye, the emission from these systems is tunable by controlling the liquid crystal system---be it through electric or thermal field effects, photochemical reactions, mechanical deformations, etc. The laser action arises from an extended interaction time between the

Scott J. Woltman

2008-01-01

313

Electronic Liquid Level Indicator  

Microsoft Academic Search

A method of continuously measuring the level of conducting and non-conducting liquids has been developed. The liquid to be measured occupies the inner space of a coaxial cylindrical condenser. As the level of liquid varies, the capacitance varies. The change in capacitance detunes a resonance resulting in a change of plate current through the oscillator tube.

S. C. Coroniti

1942-01-01

314

Liquid detection circuit  

DOEpatents

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

Regan, Thomas O. (North Aurora, IL)

1987-01-01

315

High Performance Liquid Chromatography  

E-print Network

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

Nizkorodov, Sergey

316

Vitrification and levitation of a liquid droplet on liquid nitrogen  

E-print Network

Vitrification and levitation of a liquid droplet on liquid nitrogen Young S. Songa , Douglas Adlera the liquid, when the liquid droplet comes into direct contact with liquid nitrogen. This is distinct from.e., vitrification) and the levitation of droplets on liquid nitrogen (i.e., Leidenfrost phenomenon) take place

Demirci, Utkan

317

Radiation monitor for liquids  

DOEpatents

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.

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

1999-03-02

318

Radiation monitor for liquids  

DOEpatents

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.

Koster, James E. (Los Alamos, NM); Bolton, Richard D. (Los Alamos, NM)

1999-01-01

319

Accelerating structure with linear excitation  

SciTech Connect

The switched power linac (SPL) structures require a ring-shaped laser beam pulse of uniform intensity to avoid transverse field components of the accelerating field at the center. In order to also utilize the reflection of the outgoing EM wave, the switching element has to be very close to the outer edge of the structure to ensure nearly synchronous superposition at the beam hole with the original inward going wave. It is sometimes easier to produce linear (flat) laser beams, e.g., from powerful excimer lasers which have beams of rectangular cross section. Such flat beams could be used to excite linear photocathode switches or be used to produce flat electron beam pulses in electron sources. In this paper, an accelerator structure is proposed which may be considered a variant of the SPL disk structure, but could be used with linear beams. The structure utilizes a double parabolic horn. 8 refs., 9 figs.

Fischer, J.; Srinivasan-Rao, T.

1988-03-01

320

Excited Baryons in Holographic QCD  

SciTech Connect

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.

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

2011-11-08

321

Duality of liquids  

PubMed Central

Liquids flow, and in this sense are close to gases. At the same time, interactions in liquids are strong as in solids. The combination of these two properties is believed to be the ultimate obstacle to constructing a general theory of liquids. Here, we adopt a new approach: instead of focusing on the problem of strong interactions, we zero in on the relative contributions of vibrational and diffusional motion. We show that liquid energy and specific heat are given, to a very good approximation, by their vibrational contributions as in solids over almost entire range of relaxation time in which liquids exist as such, and demonstrate that this result is consistent with liquid entropy exceeding solid entropy. Our analysis therefore reveals an interesting duality of liquids not hitherto known: they are close to solids from the thermodynamic perspective and to flowing gases. We discuss several implications of this result. PMID:23851971

Trachenko, K.; Brazhkin, V. V.

2013-01-01

322

Vibrationally Excited C4H  

NASA Astrophysics Data System (ADS)

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}{{{? }}+} ground vibrational state of C4H and were assigned to new bending vibrational levels, two each with 2{? } and 2{\\Pi } vibrational symmetry. The new levels are tentatively assigned to the 1{{? }6} and 1{{? }5} bending vibrational modes (both with 2{\\Pi } symmetry), and the 1{{? }6}+1{{? }7} and 1{{? }5}+1{{? }6} combination levels (2{? } 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{{? }7} and 2{{? }7} levels were refined. Also presented are interferometric maps of the ground state and the 1{{? }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 294296 and 304306 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.

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

2015-02-01

323

Rapid prototyping of electrochromatography chips for improved two-photon excited fluorescence detection.  

PubMed

In the present study, we introduce two-photon excitation at 532 nm for label-free fluorescence detection in chip electrochromatography. Two-photon excitation at 532 nm offers a promising alternative to one-photon excitation at 266 nm, as it enables the use of economic chip materials instead of fused silica. In order to demonstrate these benefits, one-photon and two-photon induced fluorescence detection are compared in different chip layouts and materials with respect to the achievable sensitivity in the detection of polycyclic aromatic hydrocarbons (PAHs). Customized chromatography chips with cover or bottom slides of different material and thickness are produced by means of a rapid prototyping method based on liquid-phase lithography. The design of thin bottom chips (180 ?m) enables the use of high-performance immersion objectives with low working distances, which allows one to exploit the full potential of two-photon excitation for a sensitive detection. The developed method is applied for label-free analysis of PAHs separated on a polymer monolith inside polymer glass sandwich chips made from fused silica or soda-lime glass. The obtained limits of detection range from 40 nM to 1.95 ?M, with similar sensitivities in fused silica thin bottom chips for one-photon and two-photon excitation. In deep-UV non- or less-transparent devices two-photon excitation is mandatory for label-free detection of aromatics with high sensitivity. PMID:24666258

Hackl, Claudia; Beyreiss, Reinhild; Geissler, David; Jezierski, Stefan; Belder, Detlev

2014-04-15

324

Non-Fermi liquids from holography  

SciTech Connect

We report on a potentially new class of non-Fermi liquids in (2+1)-dimensions. They are identified via the response functions of composite fermionic operators in a class of strongly interacting quantum field theories at finite density, computed using the AdS/CFT correspondence. We find strong evidence of Fermi surfaces: gapless fermionic excitations at discrete shells in momentum space. The spectral weight exhibits novel phenomena, including particle-hole asymmetry, discrete scale invariance, and scaling behavior consistent with that of a critical Fermi surface postulated by Senthil.

Liu Hong; McGreevy, John; Vegh, David [Center for Theoretical Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)

2011-03-15

325

Non-Fermi liquids from holography  

Microsoft Academic Search

We report on a potentially new class of non-Fermi liquids in\\u000a(2+1)-dimensions. They are identified via the response functions of composite\\u000afermionic operators in a class of strongly interacting quantum field theories\\u000aat finite density, computed using the AdS\\/CFT correspondence. We find strong\\u000aevidence of Fermi surfaces: gapless fermionic excitations at discrete shells in\\u000amomentum space. The spectral weight exhibits

Hong Liu; John McGreevy; David Vegh

2009-01-01

326

Quantal Density Functional Theory of Excited States  

SciTech Connect

We explain by quantal density functional theory the physics of mapping from any bound nondegenerate excited state of Schroedinger theory to an S system of noninteracting fermions with equivalent density and energy. The S system may be in a ground or excited state. In either case, the highest occupied eigenvalue is the negative of the ionization potential. We demonstrate this physics with examples. The theory further provides a new framework for calculations of atomic excited states including multiplet structure.

Sahni, Viraht; Massa, Lou; Singh, Ranbir; Slamet, Marlina

2001-09-10

327

Quantal density functional theory of excited states.  

PubMed

We explain by quantal density functional theory the physics of mapping from any bound nondegenerate excited state of Schrdinger theory to an S system of noninteracting fermions with equivalent density and energy. The S system may be in a ground or excited state. In either case, the highest occupied eigenvalue is the negative of the ionization potential. We demonstrate this physics with examples. The theory further provides a new framework for calculations of atomic excited states including multiplet structure. PMID:11531521

Sahni, V; Massa, L; Singh, R; Slamet, M

2001-09-10

328

Design evaluation: S-band exciters  

NASA Technical Reports Server (NTRS)

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.

1974-01-01

329

Intensification of Liquid-Liquid Contacting Processes  

E-print Network

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

Qiu, Zheyan

2010-09-01

330

Pi sigma* excited states in molecular photochemistry.  

PubMed

The last few years have seen a surge in interest (both theoretical and experimental) in the photochemistry of heteroaromatic molecules (e.g. azoles, phenols), which has served to highlight the importance of dissociative excited states formed by electron promotion to sigma* molecular orbitals. Such excited states--which, for brevity, are termed pi sigma* states in this Perspective article--may be populated by direct photo-excitation (though the transition cross-sections are intrinsically small), or indirectly, by non-adiabatic coupling from an optically 'bright' excited state (e.g. an excited state resulting from pi* <--pi excitation). The analogous pi sigma* excited states in prototypical hydride molecules like H(2)O and NH(3) have long been recognised. They have served as test-beds for developing concepts like Rydbergisation, conical intersections (CIs) between potential energy surfaces, and for investigating the ways in which non-adiabatic couplings at such CIs influence the eventual photofragmentation dynamics. This Perspective article seeks to highlight the continuity of behaviour revealed by the earlier small molecule studies and by the more recent studies of heteroaromatic systems, and to illustrate the photochemical importance of pi sigma* excited states in many broad families of molecules. Furthermore, the dynamical influence of such excited states is not restricted to closed shell species; the Article concludes with a brief consideration of the consequences of populating sigma* orbitals in free radical species, in molecular cations, and in dissociative electron attachment processes. PMID:20119599

Ashfold, Michael N R; King, Graeme A; Murdock, Daniel; Nix, Michael G D; Oliver, Thomas A A; Sage, Alan G

2010-02-14

331

Using photon to probe spin excitations  

NASA Astrophysics Data System (ADS)

Elementary spin excitations have attracted considerable attention in the understanding of strongly correlated materials, especially in high temperature superconductors where a full understanding of spin dynamics might reveal important information where the phase emerges in proximity of magnetic order. Photon spectroscopies, such as resonant inelastic x-ray scattering (RIXS) and optical Raman scattering, are powerful tools for the measurement of spin excitations. In this presentation, I will discuss the simulation of various spectroscopies that can reveal spin excitations, using both single- and multi-orbital models. I will show that transition metal in-direct RIXS provides information about two-magnon excitations at low energies in addition to the usual charge transfer excitations; while direct RIXS measures single spin-flip (single magnon) excitations, making it a complementary technique to inelastic neutron scattering. I also will show that Raman scattering can probe two-magnon spin excitations in correlated materials. We track the evolution of these excitations as functions of momentum and doping. These results highlight the nature of spin excitations in correlated materials and are an important step in our understanding of the corresponding experiments in real materials

Jia, Chunjing; Chen, Cheng-Chien Chen; Moritz, Brian; Devereaux, Tom

2013-03-01

332

Liquid Crystal Materials and Liquid Crystal Displays  

Microsoft Academic Search

Since the early 1970s, three major prerequisites have brought the success of the liquid crystal display (LCD) technology to its key role of today. Namely, the discovery of electro-optical field-effects on which the displays are based, the successful search for liquid crystals (LCs) with material properties that meet the complex requirements of electro-optical effects and render the effects applicable in

Martin Schadt

1997-01-01

333

Luttinger's theorem, superfluid vortices, and holography  

E-print Network

Strongly coupled field theories with gravity duals can be placed at finite density in two ways: electric field flux emanating from behind a horizon, or bulk charged fields outside of the horizon that explicitly source the ...

Iqbal, Nabil

334

Slosh wave excitation in the gravity probe-B spacecraft propulsion system  

NASA Astrophysics Data System (ADS)

The dynamical behavior of fluids in a Gravity Probe-B Spacecraft tank imposed by various frequencies of gravity jitters have been investigated. Fluid stress distribution also have been investigated. Results show that fluid stress distribution exerted on the outer and inner walls of rotating dewar are closely related to the characteristics of slosh waves excited on the liquid-vapor interface in the rotating dewar tank.

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

335

Gross violation of the WiedemannFranz law in a quasi-one-dimensional conductor  

PubMed Central

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

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

2011-01-01

336

For Distribution at the Fusion Summer Study Snowmass Colorado, July 1999 Merits & Issues for Liquid Wall Concepts  

E-print Network

For Distribution at the Fusion Summer Study Snowmass Colorado, July 1999 Merits & Issues for Liquid Distribution at the Fusion Summer Study Snowmass Colorado, July 1999 Liquid Walls Offer an Exciting Opportunity Cost, Faster R&D Path #12;For Distribution at the Fusion Summer Study Snowmass Colorado, July 1999

Abdou, Mohamed

337

Seismic response of liquid-filled tank with baffles  

NASA Astrophysics Data System (ADS)

In thispaper, the effects of a rigid baffle on the seismic response of liquid in a rigid cylindrical tank are evaluated. A baffle is an annular plate which supplies a kind of passive control on the effects of ground excitation. The contained liquid is assumed incompressible, inviscid and has irrotational motion. To estimate the seismic response, the method of superposition of modes has been applied. To analyze the rigid tank response, Laplace's equation is considered as the governing equation of the fluid domain, in both time and frequency domains. The boundary element method (BEM) is employed to evaluate the natural modes of liquid in a cylindrical tank. To gain this goal, the fluid domain is divided into two upper and lower parts partitioned by the baffle. Linearized kinematic and dynamic boundary conditions of the free surface of the contained liquid have been considered.

Shekari, Mohammad Reza

2014-09-01

338

Excess Dielectron in an Ionic Liquid as a Dynamic Bipolaron  

NASA Astrophysics Data System (ADS)

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.

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

2013-03-01

339

Local energy landscape in a simple liquid  

NASA Astrophysics Data System (ADS)

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 ?-relaxation process. The LEL offers a simple but useful starting point to discuss complex phenomena in liquids and glasses.

Iwashita, T.; Egami, T.

2014-11-01

340

Local Energy Landscape in a Simple Liquid  

E-print Network

It is difficult to relate the properties of liquids and glasses directly to their structure because of complexity in the structure which 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 on the effect of temperature and history. However, because of the highly multi-dimensional 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 excitations in the LEL corresponds to the so-called beta-relaxation process. The LEL offers a simple but useful starting point to discuss complex phenomena in liquids and glasses.

Takuya Iwashita; Takeshi Egami

2014-10-31

341

Vanishing N = 20 shell gap: study of excited states in (27,28)Ne.  

PubMed

This Letter reports on the (1)H((28)Ne, (28)Ne) and (1)H((28)Ne, (27)Ne) reactions studied at intermediate energy using a liquid hydrogen target. From the cross section populating the first 2(+) excited state of (28)Ne, and using the previously determined BE(2) value, the neutron quadrupole transition matrix element has been calculated to be M(n)=13.8 +/- 3.7 fm(2). In the neutron knockout reaction, two low-lying excited states were populated in (27)Ne. Only one of them can be interpreted by the sd shell model while the additional state may intrude from the fp shell. These experimental observations are consistent with the presence of fp shell configurations at low excitation energy in (27,28)Ne nuclei caused by a vanishing N=20 shell gap at Z=10. PMID:16712361

Dombrdi, Zs; Elekes, Z; Saito, A; Aoi, N; Baba, H; Demichi, K; Flp, Zs; Gibelin, J; Gomi, T; Hasegawa, H; Imai, N; Ishihara, M; Iwasaki, H; Kanno, S; Kawai, S; Kishida, T; Kubo, T; Kurita, K; Matsuyama, Y; Michimasa, S; Minemura, T; Motobayashi, T; Notani, M; Ohnishi, T; Ong, H J; Ota, S; Ozawa, A; Sakai, H K; Sakurai, H; Shimoura, S; Takeshita, E; Takeuchi, S; Tamaki, M; Togano, Y; Yamada, K; Yanagisawa, Y; Yoneda, K

2006-05-12

342

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

SciTech Connect

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

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

2009-07-20

343

Liquid level detector  

DOEpatents

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.

Tshishiku, Eugene M. (Augusta, GA)

2011-08-09

344

Liquid Sloshing Dynamics  

NASA Astrophysics Data System (ADS)

The problem of liquid sloshing in moving or stationary containers remains of great concern to aerospace, civil, and nuclear engineers; physicists; designers of road tankers and ship tankers; and mathematicians. Beginning with the fundamentals of liquid sloshing theory, this book takes the reader systematically from basic theory to advanced analytical and experimental results in a self-contained and coherent format. The book is divided into four sections. Part I deals with the theory of linear liquid sloshing dynamics; Part II addresses the nonlinear theory of liquid sloshing dynamics, Faraday waves, and sloshing impacts; Part III presents the problem of linear and nonlinear interaction of liquid sloshing dynamics with elastic containers and supported structures; and Part IV considers the fluid dynamics in spinning containers and microgravity sloshing. This book will be invaluable to researchers and graduate students in mechanical and aeronautical engineering, designers of liquid containers, and applied mathematicians.

Ibrahim, Raouf A.

2005-06-01

345

Monogroove liquid heat exchanger  

NASA Technical Reports Server (NTRS)

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).

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

1990-01-01

346

Dielectrically actuated liquid lens  

NASA Astrophysics Data System (ADS)

A packaged liquid lens driven by the dielectric force was demonstrated. The liquid lens consisted of a low dielectric constant droplet and a high dielectric constant sealing liquid. The two non-conductive liquids were sealed in a chamber under the condition of iso-density. Focal length of a liquid lens with an aperture of 3mm changed from 34mm to 12mm in the range of 0-200V. Hysteresis was observed in the liquid lens, with a maximum value measured of 12.5 at 120 volts in terms of droplet's contact angle. The focal spot size measured approximately 80?m. Rise and fall times were 650ms and 300ms, respectively. The lens consumed 1mW of power when applying a 200 volt, 1 kHz signal. The longitudinal and transverse spherical aberrations were estimated to be nearly invariant when the focal length exceeded 20mm.

Cheng, Chih-Cheng; Yeh, J. Andrew

2007-06-01

347

Fast Laser Excitation and Ultrahigh Strain-Rate Deformation  

SciTech Connect

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.

Robert Averback

2007-06-03

348

Quantal Density Functional Theory of Excited States  

Microsoft Academic Search

We explain by quantal density functional theory the physics of mapping from any bound nondegenerate excited state of Schrdinger theory to an S system of noninteracting fermions with equivalent density and energy. The S system may be in a ground or excited state. In either case, the highest occupied eigenvalue is the negative of the ionization potential. We demonstrate this

Viraht Sahni; Lou Massa; Ranbir Singh; Marlina Slamet

2001-01-01

349

Naphthalene in the higher triplet excited state.  

PubMed

Naphthalene in the higher triplet excited state Np(Tn) was generated from the two-step excitation method using two-colour two-laser flash photolysis technique and the lifetime of Np(Tn) was estimated to be 4.5 ps from the triplet energy quenching by quenchers such as p-dichlorobenzene, o-dicyanobenzene and carbon tetrachloride. PMID:12585401

Cai, Xichen; Hara, Michihiro; Kawai, Kiyohiko; Tojo, Sachiko; Majima, Tetsuro

2003-01-21

350

Study of excited nucleons and their structure  

SciTech Connect

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.

Burkert, Volker D. [JLAB, Newport News, VA (United States)

2014-01-01

351

What Gets a Cell Excited? Kinky Curves  

ERIC Educational Resources Information Center

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

Kay, Alan R.

2014-01-01

352

Focus Issue: Getting Excited About Glia  

NSDL National Science Digital Library

This Focus Issue of Science Signaling complements the Science Special Issue and highlights glial cell function, development, and disease. This issue draws attention to the molecular mechanisms of drug resistance of a cancer of glial origin, and to signaling between glia and neurons. Although glia may not be excitable, they are clearly an exciting group of cells.

Elizabeth M. Adler (American Association for the Advancement of Science; Science Signaling REV)

2010-11-09

353

Excitation Spectra of 1D Quantum Wires  

NASA Astrophysics Data System (ADS)

In this talk two different aspects of the excitation spectra of one dimensional (1D) semiconductor quantum wires will be discussed: (1) The nature of collective electronic excitations in 1D quantum wires; and (2) the band gap renormalization and excitonic effects in 1D quantum wires. In the first part, extensive theoretical results using the Bethe ansatz technique, the Lanczos' method, and the diagrammatic many-body theory will be presented for the spectral weight and the mode dispersion of the low-lying elementary electronic excitation spectra in 1D quantum wires with comparison to Raman Scattering experiments in GaAs quantum wires. Based on our detailed analytical and numerical results we conclude that the experimental observations are consistent with the existence of the collective charge density excitation mode, the collective spin density excitation mode, and a (low spectral weight) finite wave vector electron-hole single particle excitation mode (which arises from the finite curvature of the electron energy dispersion in the system). There is no evidence for a singlet spin density excitation mode in our calculations. In the second part, numerical solutions of the Bethe-Salpeter equation for interband excitonic transitions in 1D quantum wires will be presented. An approximate cancellation between self-energy and vertex correction effects is obtained in our calculations, providing an explaination for the experimental observation of an unshifted excitonic peak in highly excited 1D quantum wire lasers.

Wang, Daw-Wei

1998-03-01

354

Multiple parallel RF excited CO2 lasers  

Microsoft Academic Search

Dual waveguide lasers which are transversely excited in parallel from a common source of radio frequency are provided with one or more channels or bores connecting the laser cavities. The dimensions and configuration of the connecting channels are chosen so that the electric field from the applied RF excitation source will be higher in the connecting channels than in either

P. P. Chenauski; L. N. Laughman; E. H. Drinkwater

1985-01-01

355

Excitation equilibria in plasmas; a classification  

Microsoft Academic Search

This review gives a classification of the excitation kinetics ruled by electrons in plasmas. It is a study on the atomic state distribution function (ASDF) and its relation with underlying processes, which, for the case of an electron excitation kinetics (EEK) plasma, is merely a competition between free and bound electrons, the same particles in different circumstances. In a quasi

J. A. M. van der Mullen

1990-01-01

356

Low Toxic Ionic Liquids, Liquid Catanionics, and Ionic Liquid Microemulsions  

Microsoft Academic Search

In the future the demand of sustainable and low toxic surfactants and solvents will constantly increase. In this article, we present some new approaches to meet these requirements. Whereas ionic liquids are often based on imidazolium ions, we will show that there are also much less toxic ones, especially with choline as cation. Choline salts, even if solid at room

Werner Kunz; Eva Maurer; Regina Klein; Didier Touraud; Doris Rengstl; Agnes Harrar; Susanne Dengler; Oliver Zech

2011-01-01

357

Multi-photon excitation microscopy  

PubMed Central

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

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

2006-01-01

358

Multi-photon excitation microscopy.  

PubMed

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

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

2006-01-01

359

Elementary excitations and phase transitions in crystals  

SciTech Connect

The unique method of measuring elementary excitations in solids over a wide range of energy and momentum transfers is inelastic scattering of neutrons. Elementary excitations are defined as a correlated motion of atoms or spins in a solid which include phonons, magnons, rotons, or crystal field excitations. These excitations play a fundamental role in a wide variety of structural and magnetic phase transitions and provide the information in understanding the underlying microscopic mechanism of the transformation. Below, I shall review some of the relevant aspects of neutron scattering formalism related to inelastic neutron scattering and demonstrate how it has been applied to the study of phase transitions in crystals. I shall give two examples of structural phase transitions where the phonons are the elementary excitations and studies in a conventional superconductor where the phonon linewidths are a measure of the electron-phonon coupling responsible for the pairing.

Shapiro, S.M.

1993-12-31

360

Effects of core turbulence on jet excitability  

NASA Technical Reports Server (NTRS)

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.

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

1989-01-01

361

Effects of core turbulence on jet excitability  

NASA Technical Reports Server (NTRS)

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.

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

1989-01-01

362

RAPID COMMUNICATION: Simultaneous determination of anisotropic thermal conductivities of liquid crystals by means of a photothermal self-diffracting technique  

Microsoft Academic Search

Anisotropic thermal conductivities of liquid crystals were simultaneously determined by means of a photothermal self-diffracting technique. A single-mode laser beam with Gaussian profile excited refractive index distribution due to the photothermal effect in homogeneously-aligned liquid-crystal films. The refractive index distribution, which is affected by thermal conductivities of liquid crystals, transformed the incident Gaussian beam. The laser beam was self-diffracted and

Hiroshi Ono; Kazuaki Shibata

2000-01-01

363

Gluonic Excitations and Experimental Hall-D at Jefferson Lab  

SciTech Connect

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.

Stevens, Justin [MIT

2014-07-01

364

Zero-order suppression for two-photon holographic excitation.  

PubMed

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 10? 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 410?. PMID:25361128

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

2014-10-15

365

Radiation chemical effects of X-rays on liquids  

SciTech Connect

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.

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

1998-11-01

366

Chiral separation by enantioselective liquid-liquid extraction.  

PubMed

The literature on enantioselective liquid-liquid extraction (ELLE) spans more than half a century of research. Nonetheless, a comprehensive overview has not appeared during the past few decades. Enantioselective liquid-liquid extraction is a technology of interest for a wide range of chemists and chemical engineers in the fields of fine chemicals, pharmaceuticals, agrochemicals, fragrances and foods. In this review the principles and advances of resolution through enantioselective liquid-liquid extraction are discussed, starting with an introduction on the principles of enantioselective liquid-liquid extraction including host-guest chemistry, extraction and phase transfer mechanisms, and multistage liquid-liquid extraction processing. Then the literature on enantioselective liquid-liquid extraction systems is reviewed, structured on extractant classes. The following extractant classes are considered: crown ether based extractants, metal complexes and metalloids, extractants based on tartrates, and a final section with all other types of chiral extractants. PMID:21107491

Schuur, Boelo; Verkuijl, Bastiaan J V; Minnaard, Adriaan J; de Vries, Johannes G; Heeres, Hero J; Feringa, Ben L

2011-01-01

367

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

NASA Technical Reports Server (NTRS)

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

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

1995-01-01

368

Non-Fermi liquids and the Wiedemann-Franz law  

NASA Astrophysics Data System (ADS)

A general discussion of the ratio of thermal and electrical conductivities in non-Fermi liquid metals is given. In metals with sharp Drude peaks, the relevant physics is correctly organized around the slow relaxation of almost-conserved momenta. While in Fermi liquids both currents and momenta relax slowly, due to the weakness of interactions among low-energy excitations, in strongly interacting non-Fermi liquids typically only momenta relax slowly. It follows that the conductivities of such non-Fermi liquids are obtained within a fundamentally different kinematics to Fermi liquids. Among these strongly interacting non-Fermi liquids we distinguish cases with only one almost-conserved momentum, which we term quasi-hydrodynamic metals, and with many patchwise almost-conserved momenta. For all these cases, we obtain universal expressions for the ratio of conductivities that violate the Wiedemann-Franz law. We further discuss the case in which long-lived cold quasiparticles, in general with unconventional scattering rates, coexist with strongly interacting hot spots, lines, or bands. For these cases, we characterize circumstances under which non-Fermi liquid transport, in particular a linear in temperature resistivity, is and is not compatible with the Wiedemann-Franz law. We suggest the likely outcome of future transport experiments on CeCoIn5, YbRh2Si2, and Sr3Ru2O7 at their critical magnetic fields.

Mahajan, Raghu; Barkeshli, Maissam; Hartnoll, Sean A.

2013-09-01

369

Hydrogen Bonding in the Electronic Excited State  

NASA Astrophysics Data System (ADS)

Here, I will give a talk on our recent advances in electronic excited-state hydrogen-bonding dynamics and the significant role of excited-state hydrogen bonding on internal conversion (IC), electronic spectral shifts (ESS), photoinduced electron transfer (PET), fluorescence quenching (FQ), intramolecular charge transfer (ICT), and metal-to-ligand charge transfer (MLCT). The combination of various spectroscopic experiments with theoretical calculations has led to tremendous progress in excited-state hydrogen-bonding research. We first demonstrated that intermolecular hydrogen bond in excited state can be greatly strengthened or weakened for many chromophores. We have also clarified that intermolecular hydrogen-bond strengthening and weakening correspond to red-shifts and blue-shifts, respectively, in the electronic spectra. Moreover, radiationless deactivations (via IC, PET, ICT, MLCT, and so on) can be dramatically influenced by excited-state hydrogen bonding. References: [1] Guang-Jiu Zhao, and Ke-Li Han, Hydrogen Bonding in the Electronic Excited State, Accounts of Chemical Research 45, 404--413 (2012). http://pubs.acs.org/doi/pdf/10.1021/ar200135h [2] Book: Hydrogen Bonding and Transfer in the Excited State, Editors: Ke-Li Han and Guang-Jiu Zhao, ISBN: 978-0-470-66677-7, John Wiley & Sons Ltd, Chichester, UK (2011). http://onlinelibrary.wiley.com/book/10.1002/9780470669143

Zhao, Guang-Jiu; Han, Ke-Li

2013-03-01

370

Liquid Sloshing Dynamics  

Microsoft Academic Search

The problem of liquid sloshing in moving or stationary containers remains of great concern to aerospace, civil, and nuclear engineers; physicists; designers of road tankers and ship tankers; and mathematicians. Beginning with the fundamentals of liquid sloshing theory, this book takes the reader systematically from basic theory to advanced analytical and experimental results in a self-contained and coherent format. The

Raouf A. Ibrahim

2005-01-01

371

Precision liquid level sensor  

DOEpatents

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

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

1985-01-01

372

Precision liquid level sensor  

DOEpatents

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

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

1985-01-29

373

Hedging bank liquidity risk  

Microsoft Academic Search

Liquidity risk in banking has been attributed to transactions deposits and their potential to spark runs or panics. We show instead that transactions deposits help banks hedge liquidity risk from unused loan commitments. Bank stock-return volatility increases with unused commitments, but the increase is smaller for banks with high levels of transactions deposits. This deposit-lending risk management synergy becomes more

Evan Gatev; Til Schuermann; Philip E. Strahan

2006-01-01

374

Synthesis of ionic liquids  

DOEpatents

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

Dai, Sheng (Knoxville, TN); Luo, Huimin (Knoxville, TN)

2011-11-01

375

Liquid heat capacity lasers  

DOEpatents

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

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

2007-05-01

376

Synthesis of ionic liquids  

DOEpatents

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

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

2008-09-09

377

Liquid metal embrittlement  

Microsoft Academic Search

Liquid metal embrittlement is the reduction in the elongation to failure that can be produced when normally ductile solid metals are stressed while in contact with a liquid metal. This review describes its principal characteristics and the several models which have been advanced in attempts to explain the occurrence and different features of the process. Comparison between theory and experiment

M. G. Nicholas; C. F. Old

1979-01-01

378

Liquid-Seeding Atomizer  

NASA Technical Reports Server (NTRS)

Particles sprayed in drops of evaporating liquid. Placed near wind-tunnel inlet, atomizer sprays evaporating liquid containing solid particles into wind-tunnel airflow. Particles entrained in flow and scatter light, enabling flow to be observed optically. One end of atomizer slides on stationary pin to accommodate thermal expansion and contraction.

Seegmiller, Henry L. B.

1988-01-01

379

Column Liquid Chromatography.  

ERIC Educational Resources Information Center

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

Majors, Ronald E.; And Others

1984-01-01

380

Guidance Document Cryogenic Liquids  

E-print Network

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

381

LIGHT NONAQUEOUS PHASE LIQUIDS  

EPA Science Inventory

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

382

INEEL Liquid Effluent Inventory  

SciTech Connect

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

Major, C.A.

1997-06-01

383

Advanced proteomic liquid chromatography  

SciTech Connect

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

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

2012-10-26

384

Coordinating chiral ionic liquids.  

PubMed

A practical synthesis of novel coordinating chiral ionic liquids with an amino alcohol structural motif was developed starting from commercially available amino alcohols. These basic chiral ionic liquids could be successfully applied as catalysts in the asymmetric alkylation of aldehydes and gave high enantioselectivities of up to 91% ee. PMID:24163003

Vasiloiu, Maria; Leder, Sonja; Gaertner, Peter; Mereiter, Kurt; Bica, Katharina

2013-12-14

385

Fragility Control Using the Liquid-Liquid Transition in Molecular Liquid  

Microsoft Academic Search

Liquids, whose viscosity obeys the Arrhenius law, are called ``strong,'' while ``fragile'' liquids have the super-Arrhenius behavior. Here we report the first continuous control of the fragility of liquid of the same material over a wide range of fragility, using a continuous liquid-liquid transition. Our study clearly demonstrates that the fragility is not a material specific quantity, but is controlled

Rei Kurita; Hajime Tanaka

2006-01-01

386

A study of the solubility of mercury in liquid hydrocarbons  

E-print Network

of the solubility of mercury in some liquid hydrocarbons was performed over a broad span of temperatures and pressures, ranging from -150 sF to 300 uF, and 14. 7 psia to 400 psia, The hydrocarbons used in the study included octane, pentane, propane, methane... Photon Excitation IV RESULTS Solubility of Mercury in Octane Solubility of Mercury in Pentane . . . . . . . . . . . . . . . . . . . . Solubility of Mercury in Toluene . . . . . . . . . . . . . . . . . . . . Solubility of Mercury in Propane...

McFarlane, David Larimer

2012-06-07

387

Electron inelastic-scattering cross sections in liquid water  

Microsoft Academic Search

Electron inelastic-scattering cross-section data for use as input in electron track-structure calculations in liquid water are re-examined and improved. The dielectric-response function used in such cross-sections is estimated on the basis of optical data and other experimental and theoretical information. The mean excitation energy for stopping power is obtained to be 81.8 eV. which is close to the recent experimental

M. Dingfelder; D. Hantke; M. Inokuti; H. G. Paretzke

1998-01-01

388

Electron inelastic-scattering cross sections in liquid water  

Microsoft Academic Search

Electron inelastic-scattering cross-section data for use as input in electron track-structure calculations in liquid water are re-examined and improved. The dielectric-response function used in such cross-sections is estimated on the basis of optical data and other experimental and theoretical information. The mean excitation energy for stopping power is obtained to be 81.8 eV, which is close to the recent experimental

Michael Dingfelder; Detlev Hantke; Mitio Inokuti; Herwig G. Paretzke

1999-01-01

389

Utilizing electromagnetic-acoustic resonators for liquid level sensing  

Microsoft Academic Search

Electromagnetic excitation of acoustic resonators sensors as an alternative to piezoelectric and capacitive acoustic sensors provides unique benefits of remote, multi-mode measurements. Utilizing out-of-plane modes of vibration, we have employed the devices as liquid level sensors. The resolution is not limited by the wavelength (as for time-of-flight ultrasonic sensors), since small frequency changes due to interference effects of the generated

Frieder Lucklum; Bernhard Jakoby

2009-01-01

390

Superconductivity in the liquid-dimer valence-bond state  

SciTech Connect

Introducing an unambiguous prescription which converts singlet dimers into quasidipoles, we describe the low-energy excitations in the liquid-dimer state as fluctuations of the average dipole moment. The exchange of these fluctuations leads to a long-range interaction between holes in this state. This interaction favors the two-particle Bose condensate and destroys the order parameter of the one-particle Bose condensate even at zero temperature.

Ioffe, L.B.; Larkin, A.I. (Lev Davidovich Landau Institute for Theoretical Physics, ul. Kosygina 2, GSP-1, 117 940 Moscow, U.S.S.R. (SU))

1989-10-01

391

Combustion response to acoustic perturbation in liquid rocket engines  

Microsoft Academic Search

An experimental study of the effect of acoustic perturbations on combustion behavior of a model liquid propellant rocket engine has been carried out. A pair of compression drivers were used to excite transverse and longitudinal acoustic fields at strengths of up to 156.6 dB and 159.5 dB respectively in the combustion chamber of the experimental rocket engine. Propellant simulants were

Akbar Ghafourian

1993-01-01

392

FT-Kaman Spectroscopy And Pulsed Excitation  

NASA Astrophysics Data System (ADS)

It has been previously shown that equivalent results are obtained in FT-Raman spectroscopy using both pulsed and CW excitation if the following two criteria are met. 1) The pulse repetition rate must be significantly higher than the detector roll-off, and 2) The pulse length must be long enough so that interferometer resolution is not degraded. The results using a mode locked Nd/YAG laser operated with various pulse widths will be shown. The operation with pulsed excitation is necessary if one wishes to do a pump-probe Raman experiment for the detection of excited state Raman spectra. The initial results of such an experiment will be shown.

Chase, Bruce D.; Gustafson, Terry L.

1989-12-01

393

Stir membrane liquid-liquid microextraction.  

PubMed

In this article, a novel liquid phase microextraction technique, called stir membrane liquid-liquid microextraction (SM-LLME), is presented. The new approach combines the advantages of liquid phase microextraction and stirring in the same unit allowing the isolation and preconcentration of the analytes in a simple and efficient way. In the construction of the unit, a polymeric membrane is employed to protect the small volume of the extractant phase. The extraction technique is characterized for the resolution of a model analytical problem: the determination of five selected chlorophenols in water. A two-phase extraction mode is used for the extraction of the analytes with an organic solvent in which an in situ derivatization reaction takes place. The analytes are finally analyzed by gas chromatography/mass spectrometry. All the variables involved in the extraction process have been clearly identified and optimized. The new extraction mode allows the determination of chlorophenols with limits of detection in the range from 14.8 ng/L (for 2,4,5-trichlorophenol) to 22.9 ng/L (for 3-chlorophenol) with a relative standard deviation lower than 8.7% (for 2,6-dichlorophenol). PMID:21236434

Alcudia-Len, M C; Lucena, R; Crdenas, S; Valcrcel, M

2011-02-18

394

Application of Ionic Liquids in Liquid Chromatography  

Microsoft Academic Search

Interest in ionic liquids (ILs) for their potential application in analytical chemistry continues to grow. Their usefulness can be due to favourable physicochemical properties, like the lack of vapour pressure, good thermal and chemical stability as well as very good dissolution properties regarding both organic and inorganic compounds. A specific feature of ILs is that these compounds provide strong proton

Micha? Piotr Marsza??; Roman Kaliszan

2007-01-01

395

Solid-Liquid Interfacial Premelting  

E-print Network

We report the observation of a premelting transition at chemically sharp solid-liquid interfaces using molecular-dynamics simulations. The transition is observed in the solid-Alliquid-Pb system and involves the formation of a liquid interfacial...

Yang, Yang; Asta, Mark; Laird, Brian Bostian

2013-02-28

396

Landau-Placzek ratio for heat density dynamics and its application to heat capacity of liquids.  

PubMed

Exact relation for contributions to heat capacity of liquids is obtained from hydrodynamic theory. It is shown from analysis of the long-wavelength limit of heat density autocorrelation functions that the heat capacity of simple liquids is represented as a sum of two contributions due to "phonon-like" collective excitations and heat relaxation. The ratio of both contributions being the analogy of Landau-Placzek ratio for heat processes depends on the specific heats ratio. The theory of heat density autocorrelation functions in liquids is verified by computer simulations. Molecular dynamics simulations for six liquids having the ratio of specific heats ? in the range 1.1-2.3, were used for evaluation of the heat density autocorrelation functions and predicted Landau-Placzek ratio for heat processes. The dependence of contributions from collective excitations and heat relaxation process to specific heat on ? is shown to be in excellent agreement with the theory. PMID:23343280

Bryk, Taras; Ruocco, Giancarlo; Scopigno, Tullio

2013-01-21

397

Landau-Placzek ratio for heat density dynamics and its application to heat capacity of liquids  

NASA Astrophysics Data System (ADS)

Exact relation for contributions to heat capacity of liquids is obtained from hydrodynamic theory. It is shown from analysis of the long-wavelength limit of heat density autocorrelation functions that the heat capacity of simple liquids is represented as a sum of two contributions due to "phonon-like" collective excitations and heat relaxation. The ratio of both contributions being the analogy of Landau-Placzek ratio for heat processes depends on the specific heats ratio. The theory of heat density autocorrelation functions in liquids is verified by computer simulations. Molecular dynamics simulations for six liquids having the ratio of specific heats ? in the range 1.1-2.3, were used for evaluation of the heat density autocorrelation functions and predicted Landau-Placzek ratio for heat processes. The dependence of contributions from collective excitations and heat relaxation process to specific heat on ? is shown to be in excellent agreement with the theory.

Bryk, Taras; Ruocco, Giancarlo; Scopigno, Tullio

2013-01-01

398

Seismic excitation by space shuttles  

USGS Publications Warehouse

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.

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

1992-01-01

399

Nonlinear liquid oscillation in a cylindrical tank with an eccentric core barrel  

NASA Astrophysics Data System (ADS)

The nonlinear liquid motion in a partially filled cylindrical tank with an eccentric core barrel is investigated. The nonlinearity of the liquid surface oscillation is considered in the response analysis of the sloshing motion. Basic equations are derived by employing the variational principle. The nonlinear ordinary differential equations governing the liquid surface oscillation are then derived by applying Galerkin's method to the basic equations. The admissible functions of the velocity potential and liquid surface displacement are assumed to be represented by combining the modal functions obtained by the linearized analysis. The effects of the eccentricity of core barrel on liquid surface oscillation are discussed. The time histories of the liquid surface displacement are calculated to the harmonic pitching excitations. An experiment was conducted using a model tank. A good agreement was found between the theoretical and experimental results. It is shown that the nonlinear analysis is important for estimating the sloshing responses.

Takahara, Hiroki; Hara, Kensuke; Ishida, Takeshi

2012-11-01

400

MULTISCALE RECONSTRUCTION FOR PHOTON-LIMITED SHIFTED EXCITATION RAMAN SPECTROSCOPY  

E-print Network

MULTISCALE RECONSTRUCTION FOR PHOTON-LIMITED SHIFTED EXCITATION RAMAN SPECTROSCOPY Rebecca Willett excitation Raman spectroscopy results in multiple ob- servations of the sum of a material's fluorescent frequen- cies. The technique, known as Shifted Excitation Raman Difference Spectroscopy (SERDS

Willett, Rebecca

401

Students Excited by Stellar Discovery  

NASA Astrophysics Data System (ADS)

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

2011-02-01

402

Fear, excitement, and financial risk-taking.  

PubMed

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

Lee, Chan Jean; Andrade, Eduardo B

2015-01-01

403

Mode Selective Excitation Using Coherent Control Spectroscopy  

SciTech Connect

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.

Singh, Ajay K. [Radiation and Photochemistry Division, Bhabha Atomic Research Centre, Mumbai-400094 (India); School of Engineering and Science, Jacobs University Bremen, Bremen, 28759 (Germany); Konradi, Jakow; Materny, Arnulf [School of Engineering and Science, Jacobs University Bremen, Bremen, 28759 (Germany); Sarkar, Sisir K. [Radiation and Photochemistry Division, Bhabha Atomic Research Centre, Mumbai-400094 (India)

2008-11-14

404

Detecting cracked rotors using auxiliary harmonic excitation  

NASA Astrophysics Data System (ADS)

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.

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

2011-03-01

405

Acoustics of Excited Jets: A Historical Perspective  

NASA Technical Reports Server (NTRS)

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.

Brown, Cliffard A.

2005-01-01

406

Inclination Excitation in Extrasolar Planetary Systems  

NASA Astrophysics Data System (ADS)

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.

Becker, Juliette; Adams, Fred C.

2015-01-01

407

Autoparametric resonances in elastic structures carrying two rectangular tanks partially filled with liquid  

Microsoft Academic Search

Nonlinear vibrations of elastic structures carrying two liquid-filled tanks under vertical harmonic excitation are investigated. A 2:1:1 ratio of internal resonance is satisfied between the natural frequency of the structure and the lowest natural frequencies of sloshing in two rectangular liquid tanks. The theoretical analysis here is restricted to two-dimensional flow and three-dimensional Faraday waves are not considered. The finite

Takashi Ikeda

2007-01-01

408

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

NASA Technical Reports Server (NTRS)

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

Baldwin, G. C.

1981-01-01

409

Liquid sampling system  

DOEpatents

A conduit extends from a reservoir through a sampling station and back to the reservoir in a closed loop. A jet ejector in the conduit establishes suction for withdrawing liquid from the reservoir. The conduit has a self-healing septum therein upstream of the jet ejector for receiving one end of a double-ended cannula, the other end of which is received in a serum bottle for sample collection. Gas is introduced into the conduit at a gas bleed between the sample collection bottle and the reservoir. The jet ejector evacuates gas from the conduit and the bottle and aspirates a column of liquid from the reservoir at a high rate. When the withdrawn liquid reaches the jet ejector the rate of flow therethrough reduces substantially and the gas bleed increases the pressure in the conduit for driving liquid into the sample bottle, the gas bleed forming a column of gas behind the withdrawn liquid column and interrupting the withdrawal of liquid from the reservoir. In the case of hazardous and toxic liquids, the sample bottle and the jet ejector may be isolated from the reservoir and may be further isolated from a control station containing remote manipulation means for the sample bottle and control valves for the jet ejector and gas bleed.

Larson, Loren L. (Idaho Falls, ID)

1987-01-01

410

Liquid sampling system  

DOEpatents

A conduit extends from a reservoir through a sampling station and back to the reservoir in a closed loop. A jet ejector in the conduit establishes suction for withdrawing liquid from the reservoir. The conduit has a self-healing septum therein upstream of the jet ejector for receiving one end of a double-ended cannula, the other end of which is received in a serum bottle for sample collection. Gas is introduced into the conduit at a gas bleed between the sample collection bottle and the reservoir. The jet ejector evacuates gas from the conduit and the bottle and aspirates a column of liquid from the reservoir at a high rate. When the withdrawn liquid reaches the jet ejector the rate of flow therethrough reduces substantially and the gas bleed increases the pressure in the conduit for driving liquid into the sample bottle, the gas bleed forming a column of gas behind the withdrawn liquid column and interrupting the withdrawal of liquid from the reservoir. In the case of hazardous and toxic liquids, the sample bottle and the jet ejector may be isolated from the reservoir and may be further isolated from a control station containing remote manipulation means for the sample bottle and control valves for the jet ejector and gas bleed. 5 figs.

Larson, L.L.

1984-09-17

411

The Synchronous Generator Digital Excitation Regulator  

Microsoft Academic Search

This paper introduces the theory and the trait that the digital excitation used on the medium and small generator. The corn of the adjuster is Atmel89C52 singlechip. The adjuster adopts digital adjusting ,PID(Proportion Integration Differentiation) control arithmetic. It has many merits, such as briefness and trustiness, lower cost, good expansion capability and so on. By experimental testify, this excitation adjuster

Ma Linlin; Wang Bing

2010-01-01

412

Stellar Pulsations excited by a scattered mass  

E-print Network

We compute the energy spectra of the gravitational signals emitted when a mass m is scattered by the gravitational field of a star of mass M >> m. We show that, unlike black holes in similar processes, the quasi-normal modes of the star are excited, and that the amount of energy emitted in these modes depends on how close the exciting mass can get to the star.

V. Ferrari; L. Gualtieri; A. Borrelli

1999-01-22

413

Care of the patient in excited delirium.  

PubMed

Patients with excited delirium present a challenge to both law enforcement and health care personnel because handcuffs, the traditional method used to keep persons from harming themselves and others, may be fatal. The patient's survival depends upon rapid recognition and treatment, including chemical sedation, decreased environmental stimulation, intravenous fluids, and other supportive interventions. Excited delirium protocols should be established to ensure rapid and appropriate treatment to ensure patient survival and the safety of those caring for them. PMID:22766142

Gordon, Cheryl; Schmelzer, Marilee

2013-03-01

414

Evolution of locally excited avalanches in semiconductors  

E-print Network

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

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

2010-03-03

415

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

PubMed

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

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

2014-02-25

416

Temporal focusing with spatially modulated excitation.  

PubMed

Temporal focusing of ultrashort pulses has been shown to enable wide-field depth-resolved two-photon fluorescence microscopy. In this process, an entire plane in the sample is selectively excited by introduction of geometrical dispersion to an ultrashort pulse. Many applications, such as multiphoton lithography, uncaging or region-of-interest imaging, require, however, illumination patterns which significantly differ from homogeneous excitation of an entire plane in the sample. Here we consider the effects of such spatial modulation of a temporally focused excitation pattern on both the generated excitation pattern and on its axial confinement. The transition in the axial response between line illumination and wide-field illumination is characterized both theoretically and experimentally. For 2D patterning, we show that in the case of amplitude-only modulation the axial response is generally similar to that of wide-field illumination, while for phase-and-amplitude modulation the axial response slightly deteriorates when the phase variation is rapid, a regime which is shown to be relevant to excitation by beams shaped using spatial light modulators. Finally, general guidelines for the use of spatially modulated temporally focused excitation are presented. PMID:19333304

Papagiakoumou, Eirini; de Sars, Vincent; Emiliani, Valentina; Oron, Dan

2009-03-30

417

Atmospheric excitation of nonseasonal polar motion  

NASA Technical Reports Server (NTRS)

Analysis of nonseasonal polar motion excitation and atmospheric mass equatorial angular momentum (EAM) over land for the period 1980-1989 reveals a clear pattern of high power and correlation during the northern hemisphere (NH) winter followed by low power and correlation during the NH summer. A special case of this pattern occurs for longer than 14 months (from January 1987 to March 1988) when the correlation throughout the NH summer remains statistically significant. During this epoch an average of 72% of the nonseasonal polar motion excitation power at frequencies between -30 and +12 cycles/yr linearly related to atmospheric EAM over land. During the southern hemisphere winter there is significant correlation between the atmospheric EAM over midlatitude southern oceans and polar motion excitation indicating the existence of a dynamic atmosphere-ocean excitation. The atmospheric excitation power is too small to explain the large correlation during the NH winter. The effects of winds probably account for the deficit in power. The implication of these results is that there are two main excitation sources each dominant at different seasons. Atmospheric mass redistribution over land forces polar motion during the NH winter, and a dynamic atmpshere-ocean response is important during the SH winter.

Kuehne, John; Johnson, Stuart; Wilson, Clark R.

1993-01-01

418

Arrays and cascades of fluorescent liquid-liquid waveguides: broadband light sources for spectroscopy in microchannels.  

PubMed

This paper describes the fabrication and operation of fluidic broadband light sources for use "on-chip" in integrated microanalytical systems. These light sources consist of liquid-core, liquid-cladding (L2) microchannel waveguides with liquid cores containing fluorescent dyes, excited by incident light from an external halogen bulb. Simultaneous use of multiple fluorophores in a common solution, in a single L2 light source, is not possible, because energy transfer from fluorophores emitting at shorter wavelength to fluorophores emitting at longer wavelength is essentially complete. Two approaches circumvent this problem of energy transfer; both use spatial separation of the fluorophores in different streams. The first setup uses a cascade (series) of single-core, single-dye light sources of increasing absorption energy to generate a combined broadband output. The second approach uses a parallel array of single-core, single-dye light sources. The spectral content of the light output for both cascade and array light sources can be controlled through choice of flow rates and dyes. Output intensity from these light sources is comparable to standard fiber-optic spectrophotometer light sources. The paper also discusses the efficiency of energy transfer between parallel liquid cores as a function of the fluid medium (index of refraction, path length, and rate of flow). PMID:15732912

Mayers, Brian T; Vezenov, Dmitri V; Vullev, Valentine I; Whitesides, George M

2005-03-01

419

Liquid metal electric pump  

DOEpatents

An electrical pump for pumping liquid metals to high pressures in high temperature environments without the use of magnets or moving mechanical parts. The pump employs a non-porous solid electrolyte membrane, typically ceramic, specific to the liquid metal to be pumped. A DC voltage is applied across the thickness of the membrane causing ions to form and enter the membrane on the electrically positive surface, with the ions being neutralized on the opposite surface. This action provides pumping of the liquid metal from one side of the non-porous solid electrolyte membrane to the other.

Abbin, Joseph P. (Albuquerque, NM); Andraka, Charles E. (Albuquerque, NM); Lukens, Laurance L. (Albuquerque, NM); Moreno, James B. (Albuquerque, NM)

1992-01-01

420

Liquid metal electric pump  

DOEpatents

An electrical pump for pumping liquid metals to high pressures in high temperature environments without the use of magnets or moving mechanical parts. The pump employs a non-porous solid electrolyte membrane, typically ceramic, specific to the liquid metal to be pumped. A DC voltage is applied across the thickness of the membrane causing ions to form and enter the membrane on the electrically positive surface, with the ions being neutralized on the opposite surface. This action provides pumping of the liquid metal from one side of the non-porous solid electrolyte membrane to the other. 3 figs.

Abbin, J.P.; Andraka, C.E.; Lukens, L.L.; Moreno, J.B.

1992-01-14

421

Exploring Materials: Liquid Crystals  

NSDL National Science Digital Library

In this activity, learners discover that the way a material behaves on the macroscale is affected by its structure on the nanoscale. Learners investigate the properties of a heat sensitive liquid crystal and make their own liquid crystal sensor to take home. This is a fun and engaging activity, especially since liquid crystals are used in many consumer products, including cell phone displays, laptop computer screens, strip thermometers, and even "mood" rings! SAFETY: learners must be supervised when doing this activity. They must wear safety glasses to protect their eyes. Before doing this activity, read through the Material Safety Data Sheets.

Network, Nanoscale I.; Sciencenter

2010-01-01

422

114. WEST SIDE OF LIQUID OXYGEN CONTROL ROOM (205). LIQUID ...  

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

114. WEST SIDE OF LIQUID OXYGEN CONTROL ROOM (205). LIQUID NITROGEN (LN2) SUBCOOLER ON LEFT; SKID 8, LIQUID OXYGEN CONTROLLER FOR SWITCHING BETWEEN RAPID-LOAD AND TOPPING ON RIGHT. LIQUID OXYGEN LINE FROM SKID 9A AT RIGHT EDGE OF PHOTO. - Vandenberg Air Force Base, Space Launch Complex 3, Launch Pad 3 East, Napa & Alden Roads, Lompoc, Santa Barbara County, CA

423

Surface plasmon resonance on the surface: metal - liquid crystal layer  

NASA Astrophysics Data System (ADS)

Surface plasmon resonance (SPR) is widely used in different types of optical detection schemes and for light manipulation at sub-wavelength scale. Usually Kretschmann configuration is used for effective SPR excitation. There are a lot of experimental and theoretical investigations about the influence of the dielectric, adjacent to the metal, on SPR. However, till now the influence on liquid crystal layer, adjacent to the metal, is not considered to our best knowledge. The purpose of the present paper is to cover this gap. We simulate the influence of thin layer of liquid crystal, adjacent to the metal, on the SPR characteristics. For this purpose Maxwell equations are numerically solved for layer structure: prism/gold/liquid crystal/air. The light reflection spectra are calculated for chiral structure of ferroelectric smectic C (SmC*) liquid crystal layer. The angular and wavelength response are considered. Special attention is paid to SPR excitation for variation of tilt angle and different angle of incident light. The influence of SPR of the pitch length and cell thickness is also considered.

Zhelyazkova, K.; Petrov, M.; Katranchev, B.; Dyankov, G.

2014-12-01

424

Liquid Crystal IR Detector  

NSDL National Science Digital Library

This is a student activity on the detection of a warm object with a liquid crystal sheet. This activity also can be a simulation of the detection of infrared radiation. The "For Further Research" section includes questions for the student.

2012-10-30

425

Diet - full liquid  

MedlinePLUS

... liquid when they are at room temperature, like ice cream. It also includes strained creamy soups, tea, juice, ... Butter, margarine, oil, cream, custard, and pudding Plain ice cream, frozen yogurt, and sherbet. Fruit ices and popsicles ...

426

Liquid Assets: Public Health  

NSDL National Science Digital Library

This video segment from a WPSU documentary Liquid Assets connects public health to the availability of clean and safe drinking water and elaborates on the threats our bodies face due to increasing kinds and quantities of pollutants.

Wpsu

2008-11-19

427

Basic Liquid Chromatography  

NSDL National Science Digital Library

This online textbook offers a variety of information on high performance liquid chromatography (HPLC). Topics covered include instruments, detectors, theory, column selection, and pH effect. This website also contains links to a glossary, useful links, and manufacturer websites.

Dr. Yuri Kazakevich

428

A lateral field excited ZnO film bulk acoustic wave sensor working in viscous environments  

NASA Astrophysics Data System (ADS)

We present a lateral field excited ZnO film bulk acoustic resonator (FBAR) operated in pure-shear mode and analyze its performances in viscous liquids. The electrodes of the device are located on the film surface and normal to the c-axis of the ZnO film. The proposed device works near 1.44 GHz with a Q-factor up to 360 in air and 310 in water, which are higher than those of the quasi-shear thickness field excited FBAR. The resonant frequency is decreased with the increasing square root of the product of the viscosity and density with a linear dependence in the viscosity below 148.7 mPa s. The mass sensitivity of 670 Hz cm2 ng-1 was measured by monitoring the frequency change during the volatilization of saline solution loaded on the resonator. In addition, the levels of the noise and the mass resolutions were measured in various viscous environments. The proposed device yields the mass resolution of 670 Hz cm2 ng-1 and the high mass resolution of 0.06 ng cm-2. These results indicated that the lateral field excited ZnO FBAR had superior sensitivity for the bio-sensing applications in viscous biological liquids.

Chen, Da; Wang, Jingjing; Xu, Yan; Li, Dehua; Zhang, Liuyin; Liu, Weihui

2013-09-01

429

Liquid contact resonance AFM: analytical models, experiments, and limitations  

NASA Astrophysics Data System (ADS)

Contact resonance AFM (CR-AFM) is a scanning probe microscopy technique that utilizes the contact resonances of the AFM cantilever for concurrent imaging of topography and surface stiffness. The technique has not been used in liquid until recently due to analytical and experimental difficulties, associated with viscous damping of cantilever vibrations and fluid loading effects. To address these difficulties, (i) an analytical approach for contact resonances in liquid is developed, and (ii) direct excitation of the contact resonances is demonstrated by actuating the cantilever directly in a magnetic field. By implementing the analytical approach and the direct actuation through magnetic particles, quantitative stiffness imaging on surfaces with a wide range of stiffness can be achieved in liquid with soft cantilevers and low contact forces.

Parlak, Zehra; Tu, Qing; Zauscher, Stefan

2014-11-01

430

Applications of ionic liquids.  

PubMed

Ionic liquids have recently gained popularity in the scientific community owing to their special properties and characteristics. One of the reasons why ionic liquids have been termed "green solvents" is due to their negligible vapour pressure. Their use in electrochemical, biological and metal extraction applications is discussed. Wide research has been carried out for their use in batteries, solar panels, fuel cells, drug deliveries and biomass pretreatments. This work aims to consolidate the various findings from previous works in these areas. PMID:22711528

Patel, Divia Dinesh; Lee, Jong-Min

2012-06-01

431

Liquid metal embrittlement mechanism  

Microsoft Academic Search

Liquid metal embrittlement was studied in the following two aspects. First the first principle and Chen-Nanxian three-dimensional\\u000a lattice reverse method were employed to obtain the effective potentials for Al-Ga and Ga-Ga. Then with the molecular dynamics\\u000a simulation, the influence of liquid metal adsorption on dislocation emission was studied. The simulated result shows that\\u000a after Ga atoms are adsorbed on the

Guohui Zhou; Xiaomin Liu; Farong Wan; Lijie Qiao; Wuyang Chu; Wenqing Zhang; Nanxian Chen; Fuxin Zhou

1999-01-01

432

A liquid microbarograph  

Microsoft Academic Search

A liquid microbarograph has been designed for continuous recording of variations in the atmospheric pressure with characteristic\\u000a times ranging from 0.25 s to a few hours with a resolution of 0.02 Pa or better. The instrument is based on a sensor composed\\u000a of two communicating vessels filled with transformer oil. A shift of the liquid level is recorded by the

O. I. Akhmetov; S. V. Pilgaev; Yu. V. Fedorenko; D. V. Dneprovskii

2010-01-01

433

Advanced proteomic liquid chromatography  

PubMed Central

Liquid chromatography coupled with mass spectrometry is the predominant platform used to analyze proteomics samples consisting of large numbers of proteins and their proteolytic products (e.g., truncated polypeptides) and spanning a wide range of relative concentrations. This review provides an overview of advanced capillary liquid chromatography techniques and methodologies that greatly improve separation resolving power and proteomics analysis coverage, sensitivity, and throughput. PMID:22840822

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

2012-01-01

434

Apparatus and method for comparing corresponding acoustic resonances in liquids  

DOEpatents

Apparatus and method are disclosed for comparing corresponding acoustic resonances in liquids. The present invention permits the measurement of certain characteristics of liquids which affect the speed of sound therein. For example, a direct correlation between the octane rating of gasoline and the speed of sound in a gasoline sample has been experimentally observed. Therefore, changes in the speed of sound therein can be utilized as a sensitive parameter for determining changes in composition of a liquid sample. The present apparatus establishes interference patterns inside of a liquid without requiring the use of very thin, rigorously parallel ceramic discs, but rather uses readily available piezoelectric transducers attached to the outside surface of the usual container for the liquid and located on the same side thereof in the vicinity of one another. That is, various receptacle geometries may be employed, and the driving and receiving transducers may be located on the same side of the receptacle. The cell may also be constructed of any material that is inert to the liquid under investigation. A single-transducer embodiment, where the same transducer provides the excitation to the sample container and receives signals impressed therein, is also described. 5 figs.

Sinha, D.N.

1999-03-23

435

Astronomie avec Miroirs Liquides  

NASA Astrophysics Data System (ADS)

Cette thse dmontre que la technologie des miroirs liquides a atteint une maturit qui permet de l'appliquer la recherche astronomique. Les tlescopes miroir liquide offrent des images astronomiques de qualit comparable celle des tlescopes conventionels utiliss dans des conditions similaires. La premire partie de la thse prsente le premier tlescope a miroir liquide ddi la recherche astronomique: le 2,7 m de University of British Columbia-Universit Uval (UBC-UL). Elle donne galement les renseignements techniques utiles pour l'exploitation des tlescopes miroir liquide en milieu extrieur. La deuxime partie de la thse analyse les donnes de la saison 1996 du tlescope miroir liquide de 3 m du NASA Orbital Debris Observatory (NODO). Une comparaison avec les observations effectues avec des tlescopes conventionels, publies dans la littrature, dmontre la bonne qualit des donnes du NODO. Une recherche d'objets particuliers, parmi les 20 000 objets rpertoris pendant la saison 1996, dmontre le potentiel des miroirs liquides pour les projets d'astronomie demandant de grandes surfaces collectrices sur de longues priodes de temps.

Cabanac, Remi Andre

436

Liquidity Risk and Syndicate Structure  

Microsoft Academic Search

We offer a new explanation of loan syndicate structure based on banks' comparative advantage in managing systematic liquidity risk. When a syndicated loan to a rated borrower has systematic liquidity risk, the fraction of passive participant lenders that are banks is about 8% higher than for loans without liquidity risk. In contrast, liquidity risk does not explain the share of

Evan Gatev; Philip Strahan

2008-01-01

437

Experiments with electron bubbles in liquid helium  

NASA Astrophysics Data System (ADS)

When a free electron is injected into liquid helium, it forms a microscopic bubble essentially free of helium atoms. The electron bubble is an excellent textbook example of a quantum mechanical particle confined in a potential well. The bubble is also a powerful tool to study superfluidity. In this dissertation, we describe various experiments on electron bubbles using standard ultrasonic techniques. By using a focused sound wave, we create a region in liquid helium where the pressure was negative. The bubble becomes unstable, and can grow without limit when the ambient pressure is lower than some critical value. This macroscopic bubble can then be detected by light scattering. The critical pressure of the bubble depends on many factors. For example, a bubble containing an electron in an excited state has a lower magnitude of critical pressure, and is therefore easier to explode than a bubble with the electron in the ground state. Similarly, bubbles trapped on vortices are easier to explode than normal, untrapped bubbles. In our experiments, we injected electrons in liquid helium by either a field emission tip or a radioactive beta source. We investigated the different experimental conditions under which the bubbles were trapped on vortices. We measured the difference of critical pressures between bubbles on and off vortices as a function of temperature. In the course of our experiments, we were able to detect electrons that were formed by the Penning ionization of dimers. At temperatures lower than 1 K, we have discovered new objects that can be exploded very easily. These objects depend on different experimental parameters in a complicated way, and are not completely understood. In a second series of experiments, we used infrared radiation to excite the electron bubbles. By analyzing the data carefully, we estimated the lifetime of these excited state bubbles; and concluded that the decay mechanism is non-radiative in nature. We also studied the effect of infrared radiation on bubbles trapped on vortices. Finally, we measured the current arising from the secondary ionization of the beta particles emitted from a radioactive source. The current had an interesting dependence on different experimental parameters, especially temperature and electric field.

Ghosh, Ambarish

438

Femtosecond Timescale Evolution of Pyrrole Electronic Excitation  

NASA Astrophysics Data System (ADS)

Pyrrole is a simple aromatic molecule with relevantchromophoric properties in biology. Although its apparent simplicity, it shows a complicated dynamics after excitation in the near part of the UV absorption spectrum, which results from the interplay between the bright ??^* and the dark dissociative ??^* electronic transitions. Herein, we present a time resolved study with ultrafast resolution on the relaxation dynamics of isolated pyrrole, after excitation in the 265-217 nm range. Two lifetimes of 19 and 15 fs, which are associated with the internal conversion from the bright 1B2 ??^* state and the propagation of the wavepacket on the ??^* state, respectively, are found in the studied energy interval. The work also explores the consequences of non resonant adiabatic excitation of the system when broadband femtosecond pulses are employed to prepare the molecule in the targeted electronic states, revealing the key implication of this type of coherent phenomena. The collected data reveal that the bright 1B2 ??^* state is adiabatically populated at excitation wavelengths far away from resonance, providing an efficient way to reach the ??^* state. The recorded transients are fit employing a coherent model that provides a comprehensive view of the dynamical processes pyrrole undergoes after excitation by ultrashort light pulses. M. N. R. Ashfold, B. Cronin, A. L. Devine, R. N. Dixon and M. G. D. Nix Science, 312, 1637-1640, 2006.

Montero, Raul; Conde, Alvaro Peralta; Ovejas, Virginia; Castano, Fernando; Longarte, Asier

2012-06-01

439

Stability of excited atoms in small cavities  

NASA Astrophysics Data System (ADS)

We consider a system consisting of an atom in the approximation of a harmonic oscillator of frequency ?bar, coupled to the scalar potential inside a spherical reflecting cavity of radius R. We use dressed states introduced in a previous publication [Andion, Malbouisson, and Mattos Neto, J. Phys. A 34, 3735 (2001)], which allow a nonperturbative unified description of the atom radiation process, in both cases, of a finite or an arbitrarily large cavity. We perform a study of the energy distribution in a small cavity, with the initial condition that the atom is in the first excited state and we conclude for the quasi-stability of the excited atom. For instance, for a frequency ?bar of the order ?bar~4.001014/s (in the visible red), starting from the initial condition that the atom is in the first excited level, we find that for a cavity with diameter 2R~1.010-6 m, the probability of the atom being at any time still in the first excited level, will be of the order of 97%. For a typical microwave frequency ?bar~2.001010/s we find stability in the first excited state also of the order of 97% for a cavity radius R~1.410-2 m.

Flores-Hidalgo, G.; Malbouisson, A. P.; Milla, Y. W.

2002-06-01

440

The Exciting Wavelength of Extended Red Emission  

NASA Astrophysics Data System (ADS)

We propose to determine the wavelength of the photons which excite Extended Red Emission {ERE} by mapping the small scale structure of ERE and molecular hydrogen {H_2} in the reflection nebulae NGC 2023 and 7023. Both of these nebulae display sharp narrow ERE-filaments within photodissociation regions {PDR} which also show infrared H_2 fluorescence. In these opically thick filaments, different wavelength photons penetrate to different depths. By comparing the widths of these filaments in ERE and H_2 we will determine the exciting wavelength of ERE. This is possible because the combined opacity of dust and H_2 to the exciting radiation {lambda < 1100 A} of H_2 fluorescence is known, and the comparison of the thickness of the ERE and H_2 filaments will allow a determination of the dust opacity at the wavelength at which ERE is being excited. This is a sensitive test to distinguish between different materials which have been proposed as the carrier of ERE {e.g., carbon or silicon nanoparticles, polycyclic aromatic hydrocarbon molecules, hydrogenated amorphous carbon, etc.}, because the photoluminescense excitation spectra of these different materials differ by large amounts. Identifying the material which produces ERE is important as recent work on ERE in the diffuse interstellar medium has shown that the material which produces ERE comprises a significant component of dust grains.

Gordon, Karl

2003-07-01

441

Targeting individual excited states in DMRG.  

NASA Astrophysics Data System (ADS)

The low-lying excited states of ?-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.

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

2007-03-01

442

Tone-excited jet: Theory and experiments  

NASA Technical Reports Server (NTRS)

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.

Ahuja, K. K.; Lepicovsky, J.; Tam, C. K. W.; Morris, P. J.; Burrin, R. H.

1982-01-01

443

RAPID COMMUNICATION: Simultaneous determination of anisotropic thermal conductivities of liquid crystals by means of a photothermal self-diffracting technique  

NASA Astrophysics Data System (ADS)

Anisotropic thermal conductivities of liquid crystals were simultaneously determined by means of a photothermal self-diffracting technique. A single-mode laser beam with Gaussian profile excited refractive index distribution due to the photothermal effect in homogeneously-aligned liquid-crystal films. The refractive index distribution, which is affected by thermal conductivities of liquid crystals, transformed the incident Gaussian beam. The laser beam was self-diffracted and thermal conductivities of liquid crystals were determined by characterizing the beam profile by both Kirchhoff's diffraction theory and heat conduction analysis.

Ono, Hiroshi; Shibata, Kazuaki

2000-11-01

444

Liquid crystal photonics: optical switching and image storage using nematic liquid crystals and ferroelectric liquid crystals  

Microsoft Academic Search

Manipulation of light by light as a stimulus by the use of liquid-crystalline materials was explored, which was aimed at optical switching, optical image storage and optical display. Two types of the liquid-crystalline materials are used: nematic liquid crystals and ferroelectric liquid (FLCs). Several kinds of optical switching and image storage systems were demonstrated by means of photochromic molecules and

Atsushi Shishido; Osamu Tsutsumi; Akihiko Kanazawa; Takeshi Shiono; Tomiki Ikeda

1997-01-01

445

Excited light meson spectroscopy from lattice QCD  

SciTech Connect

I report on recent progress in calculating excited meson spectra using lattice QCD, emphasizing results and phenomenology. With novel techniques we can now extract extensive spectra of excited mesons with high statistical precision, including spin-four states and those with exotic quantum numbers. As well as isovector meson spectra, I will present new calculations of the spectrum of excited light isoscalar mesons, something that has up to now been a challenge for lattice QCD. I show determinations of the flavor content of these mesons, including the eta-eta' mixing angle, providing a window on annihilation dynamics in QCD. I will also discuss recent work on using lattice QCD to map out the energy-dependent phase shift in pi-pi scattering and future applications of the methodology to the study of resonances and decays.

Christopher Thomas, Hadron Spectrum Collaboration

2012-04-01

446

Shear layer excitation, experiment versus theory  

NASA Technical Reports Server (NTRS)

The acoustical excitation of shear layers is investigated. Acoustical excitation causes the so-called orderly structures in shear layers and jets. Also, the deviations in the spreading rate between different shear layer experiments are due to the same excitation mechanism. Measurements in the linear interaction region close to the edge from which the shear layer is shed are examined. Two sets of experiments (Houston 1981 and Berlin 1983/84) are discussed. The measurements were carried out with shear layers in air using hot wire anemometers and microphones. The agreement between these measurements and the theory is good. Even details of the fluctuating flow field correspond to theoretical predictions, such as the local occurrence of negative phase speeds.

Bechert, D. W.; Stahl, B.

1984-01-01

447

Ultrasoft fermionic excitation at finite chemical potential  

NASA Astrophysics Data System (ADS)

It has been suggested previously that an ultrasoft fermionic excitation develops, albeit with a small spectral weight, in a system of massless fermions and scalar bosons with Yukawa interaction at high temperature T. In this paper we study how this excitation is modified at finite chemical potential ?. We relate the existence of the ultrasoft mode to symmetries, in particular charge conjugation, and a supersymmetry of the free system which is spontaneously broken by finite temperature and finite density effects, as argued earlier by Lebedev and Smilga. A nonvanishing chemical potential breaks both symmetries explicitly and maximally at zero temperature where the mode ceases to exist. A detailed calculation indicates that the ultrasoft excitation persists as long as T?0.71?.

Blaizot, Jean-Paul; Satow, Daisuke

2014-05-01

448

BLAIR'S "CONDENSER THEORY" OF NERVE EXCITATION.  

PubMed

Blair's recent theory of excitation is analysed with the following conclusions: 1. The theory is inapplicable to currents of long duration; i.e., slowly increasing currents and the opening excitation. 2. The theory is a modification of the condenser theory of excitation but the modification is to be rejected on three grounds: (a) The modification has no obvious physical significance. (b) It does not in fact remedy the divergence between calculation and observation. (c) It leads to certain conclusions of a surprising kind which are contrary to observed fact. 3. The qualitative value of the condenser theory is demonstrated by the fairly close agreement between calculation and observation over a considerable field of enquiry. PMID:19872794

Rushton, W A

1934-01-20

449

Collective excitations in itinerant spiral magnets  

NASA Astrophysics Data System (ADS)

We investigate the coupled charge and spin collective excitations in the spiral phases of the two-dimensional Hubbard model using a generalized random-phase approximation. Already for small doping the spin-wave excitations are strongly renormalized due to low-energy particle-hole excitations. Besides the three Goldstone modes of the spiral state the dynamical susceptibility reveals an extra zero mode for low doping and strong coupling values signaling an intrinsic instability of the homogeneous spiral state. In addition, near-zero modes are found in the vicinity of the spiral pitch wave number for out-of-plane spin fluctuations. Their origin is found to be the near degeneracy with staggered noncoplanar spiral states which, however, are not the lowest energy Hartree-Fock solutions among the homogeneous spiral states.

Kampf, A. P.

1996-01-01

450

Site-selective liquid-prase vibrational overtone photochemistry of hydroxyhexadiene  

NASA Astrophysics Data System (ADS)

Vibrational overtone excitation of 1,5-hexadien-3-ol in the liquid phase yields the rearrangement product 5-hexanal. It is shown that the product is only formed when a CH oscillator is pumped while the reaction does not proceed upon pumping of the OH oscillator.

Schwebel, Alan; Brestel, Mordechai; Yogev, Amnon

1984-06-01

451

A liquid xenon imaging telescope for 1-30 MeV gamma-ray astrophysics  

Microsoft Academic Search

A study of the primary scintillation light in liquid xenon excited by 241 Am alpha particles and 207 Bi internal conversion electrons are discussed. The time dependence and the intensity of the light at different field strengths have been measured with a specifically designed chamber, equipped with a CaF2 light transmitting window coupled to a UV sensitive PMT. The time

Elena Aprile; Reshmi Mukherjee; Masayo Suzuki

1989-01-01

452

Photo-patterning micro-mirror devices using azo dye-doped cholesteric liquid crystals  

E-print Network

Photo-patterning micro-mirror devices using azo dye-doped cholesteric liquid crystals Tsung: A simple method for fabricating patternable micro-mirror devices by photo-induced alignment of dye to nearly perfect planar by the photo-excited adsorbed dyes. This structure transformation leads

Wu, Shin-Tson

453

Appearance of ``Fragile'' Fermi Liquids in Finite-Width Mott Insulators Sandwiched between Metallic Leads  

E-print Network

temperatures, the Mott insulator develops a thermal excitation induced (one electron) density of states (DOSAppearance of ``Fragile'' Fermi Liquids in Finite-Width Mott Insulators Sandwiched between Metallic that the normal-metal proximity effect could force any finite number of Mott-insulating ``barrier'' planes

Freericks, Jim

454

Single chip solution to capacitive liquid crystal chemical and biological sensor  

Microsoft Academic Search

In this paper a CMOS single chip capacitive liquid crystal chemical and biological sensor is presented. Two on-chip interdigitated capacitors provide differential sensor measurement. The system consists of a low noise preamplifier, synchronous demodulator and low pass filter. For high sensitivity detection proper excitation signal voltage and frequency have been investigated and the preamplifier noise has been minimized using a

Alireza Hassanzadeh; Robert G. Lindquist

2011-01-01

455

Modeling subsurface charge accumulation images of a quantum Hall liquid S. H. Tessmer  

E-print Network

Modeling subsurface charge accumulation images of a quantum Hall liquid S. H. Tessmer Department a detailed numerical modeling of these data. At a basic level, the method produces results that agree well potential, as indi- cated in Fig. 1. Due to capacitive coupling, the excitation causes charge to flow

Finkelstein, Gleb

456

Laser generation of acoustic waves in liquids using a Helmholtz resonance photoacoustic cell  

Microsoft Academic Search

The thermoelastic mechanism for laser generation of acoustic waves in liquids is presented first of all. The amplitude of the acoustic waves excited by this mechanism is so small that most of time it can not satisfy application requirements. In our research, a Helmholtz resonance photoacoustic cell is employed to resolve the problem. It consists of a sample cell and

Qiushi Li; Hong Luo; Zefeng Wang; Yongming Hu

2008-01-01

457

Photophysical study and theoretical calculations of an ionic liquid crystal bearing oxadiazole  

NASA Astrophysics Data System (ADS)

We report a detailed photophysical study of 1-dodecyl-4-[5-(4-dodecyloxyphenyl)-1,3,4-oxadiazole-2-yl]pyridinium bromide (454Do), a cationic amphiphile that behaves as a fluorescent liquid crystal. Excitation and emission spectra of the probe in different environments result in significant changes in quantum yields which are correlated with changes in lifetimes and theoretical calculations.

Pedro, Jorge A.; Mora, Jos R.; Westphal, Eduard; Gallardo, Hugo; Fiedler, Haidi D.; Nome, Faruk

2012-05-01

458

The photodissociation and reaction dynamics of vibrationally excited molecules  

SciTech Connect

We have used combined vibrational overtone excitation and laser induced fluorescence detection to study dissociation dynamics of hydroxylamine (NH[sub 2]OH), have performed our first laser induced grating experiments on water, and have begun assembling a new apparatus for preparing vibrationally excited molecules with simulated Raman excitation. We study role of vibrational excitation in photodissociation dynamics by using a vibrational state preparation technique, such as vibrational overtone excitation or stimulated Raman excitation, to create molecules with particular nuclear motions and then to excite that molecule to a dissociative electronic state.

Not Available

1993-01-01

459

Explorations in Dirac Fermions and Spin Liquids  

NASA Astrophysics Data System (ADS)

A significant portion of this dissertation is devoted to the study of the effects of impurities in substances whose low energy modes can be described by fermions obeying the gapless Dirac equation in 2+1 dimensions. First, we examine the case of a spin vacancy in the staggered flux spin liquid whose excitations are Dirac fermions coupled to a U(1) gauge field. This vacancy leads to an anomalous Curie susceptibility and does not induce any local orders. Next, a Coulomb charge impurity placed on clean graphene is considered. We find that the Dirac quasiparticles in graphene do not screen the impurity charge, to all orders in perturbation theory. However, electronic correlations are found to induce a cloud of charge having the same sign as the impurity charge. We also analyze the case of a local impurity in graphene in the presence of a magnetic field and derive the spatial fourier transform of tunneling spectroscopy data obtained on an almost-clean graphene sheet in a magnetic field. We then move on to Strong Topological Insulators (STI) whose surfaces are inhabited by an odd number of Dirac fermion species. Local impurities on the STI surface are found to induce resonance(s) in the local density of states (LDOS) in their vicinity. In the case of magnetic impurities that may be approximated by classical spins, we show the existence of RKKY interactions that favor ferromagnetic aligning of randomly placed impurity spins perpendicular to the STI surface when the doping is insignificant. Finally we also consider the effects of a step edge on the STI surface and calculate the spatial decay of LDOS perturbations away from it. The last chapter of this dissertation contains the theory for a new kind of spin liquid in a system of spin halves arranged in a triangular lattice, whose excitations are spin one Majorana fermions. This gapless spin liquid is found to possess certain properties that are exhibited by the recently discovered spin liquid state in the organic charge transfer salt EtMe 3Sb(Pd(dmit)2)2.

Biswas, Rudro Rana

2011-12-01

460

Brillouin scattering in liquids  

Microsoft Academic Search

The development of monochromatic, intense, and highly directional laser light sources has made it possible to measure accurately the velocity, the frequency, and the lifetimes of thermally excited hypersonic sound waves. The technique employed is to study the spectrum of the light scattered from the thermally generated sound waves in the medium. A theory is presented which demonstrates explicitly the

G. Benedek; T. Greytak

1965-01-01

461

PHOTOEMISSION AS A PROBE OF THE COLLECTIVE EXCITATIONS IN CONDENSED MATTER SYSTEMS.  

SciTech Connect

New developments in instrumentation have recently allowed photoemission measurements to be performed with very high energy and momentum resolution.[1] This has allowed detailed studies of the self-energy corrections to the lifetime and mass renormalization of excitations in the vicinity of the Fermi level. These developments come at an opportune time. Indeed the discovery of high temperature superconductivity in the cuprates and related systems is presenting a range of challenges for condensed matter physics.[2] Does the mechanism of high T{sub c} superconductivity represent new physics? Do we need to go beyond Landau's concept of the Fermi liquid?[3] What, if any, is the evidence for the presence or absence of quasiparticles in the excitation spectra of these complex oxides? The energy resolution of the new instruments is comparable to or better than the energy or temperature scale of superconductivity and the energy of many collective excitations. As such, photoemission has again become recognized as an important probe of condensed matter. Studies of the high T{sub c} superconductors and related materials are aided by the observation that they are two dimensional. To understand this, we note that the photoemission process results in both an excited photoelectron and a photohole in the final state. Thus the experimentally measured photoemission peak is broadened to a width reflecting contributions from both the finite lifetime of the photohole and the momentum broadening of the outgoing photoelectron.

JOHNSON, P.D.; VALLA, T.

2006-08-01

462

Ab initio calculation of the electronic absorption spectrum of liquid water  

SciTech Connect

The electronic absorption spectrum of liquid water was investigated by coupling a one-body energy decomposition scheme to configurations generated by classical and Born-Oppenheimer Molecular Dynamics (BOMD). A Frenkel exciton Hamiltonian formalism was adopted and the excitation energies in the liquid phase were calculated with the equation of motion coupled cluster with single and double excitations method. Molecular dynamics configurations were generated by different approaches. Classical MD were carried out with the TIP4P-Ew and AMOEBA force fields. The BLYP and BLYP-D3 exchange-correlation functionals were used in BOMD. Theoretical and experimental results for the electronic absorption spectrum of liquid water are in good agreement. Emphasis is placed on the relationship between the structure of liquid water predicted by the different models and the electronic absorption spectrum. The theoretical gas to liquid phase blue-shift of the peak positions of the electronic absorption spectrum is in good agreement with experiment. The overall shift is determined by a competition between the OH stretching of the water monomer in liquid water that leads to a red-shift and polarization effects that induce a blue-shift. The results illustrate the importance of coupling many-body energy decomposition schemes to molecular dynamics configurations to carry out ab initio calculations of the electronic properties in liquid phase.

Martiniano, Hugo F. M. C.; Galamba, Nuno [Grupo de Fsica Matemtica da Universidade de Lisboa, Av. Professor Gama Pinto 2, 1649-003 Lisboa (Portugal)] [Grupo de Fsica Matemtica da Universidade de Lisboa, Av. Professor Gama Pinto 2, 1649-003 Lisboa (Portugal); Cabral, Benedito J. Costa, E-mail: ben@cii.fc.ul.pt [Grupo de Fsica Matemtica da Universidade de Lisboa, Av. Professor Gama Pinto 2, 1649-003 Lisboa (Portugal) [Grupo de Fsica Matemtica da Universidade de Lisboa, Av. Professor Gama Pinto 2, 1649-003 Lisboa (Portugal); Departamento de Qumica e Bioqumica, Faculdade de Cincias, Universidade de Lisboa, 1749-016 Lisboa (Portugal); Instituto de Fsica da Universidade de So Paulo, CP 66318, 05314-970 So Paulo, SP (Brazil)

2014-04-28

463

Exciting Baryons: now and in the future  

SciTech Connect

This is the final talk of NSTAR2011 conference. It is not a summary talk, but rather a looking forward to what still needs to be done in excited baryon physics. In particular, we need to hone our tools connecting experimental inputs with QCD. At present we rely on models that often have doubtful connections with the underlying theory, and this needs to be dramatically improved, if we are to reach definitive conclusions about the relevant degrees of freedom of excited baryons. Conclusions that we want to have by NSTAR2021.

Michael Pennington

2012-04-01

464

Charmonium excited state spectrum in lattice QCD  

SciTech Connect

Working with a large basis of covariant derivative-based meson interpolating fields we demonstrate the feasibility of reliably extracting multiple excited states using a variational method. The study is performed on quenched anisotropic lattices with clover quarks at the charm mass. We demonstrate how a knowledge of the continuum limit of a lattice interpolating field can give additional spin-assignment information, even at a single lattice spacing, via the overlap factors of interpolating field and state. Excited state masses are systematically high with respect to quark potential model predictions and, where they exist, experimental states. We conclude that this is most likely a result of the quenched approximation.

Jozef Dudek; Robert Edwards; Nilmani Mathur; David Richards

2008-02-01

465

Stretched-State Excitations with the  

Microsoft Academic Search

Neutron time-of-fight spectra were obtained for the ^{14}C(p,n) ^{14}N, ^{18 }O(p,n)^{18}F, and ^{30}Si(p,n) ^{30}P reactions at 135 MeV with the beam-swinger system at the Indiana University Cyclotron Facility. Excitation-energy spectra and the differential cross sections for the observed excitations in these reactions were extracted over the momentum transfer range from 0 to 2.7 fm^{-1}. The primary goal of this work

Luis Alberto Casimiro Garcia

1992-01-01

466

Gluonic excitations in the hadronic spectrum  

SciTech Connect

QCD at low energy features a gluonic field that is strongly coupled to itself and to quarks. I will present a summary of what we know about the role that excitations of the gluonic field play in determining the spectrum of meson resonances. Recent studies using lattice techniques have suggested a phenomenology of gluonic excitations within QCD that leads to hybrid mesons with both exotic and non-exotic quantum numbers. I will discuss these calculations and describe their relationship to current experimental knowledge and to forthcoming experiments at Jefferson Lab and elsewhere.

Dudek, Jozef J. [ODU, JLAB

2014-06-01

467

Increased Excitability of Acidified Skeletal Muscle  

PubMed Central

Generation of the action potentials (AP) necessary to activate skeletal muscle fibers requires that inward membrane currents exceed outward currents and thereby depolarize the fibers to the voltage threshold for AP generation. Excitability therefore depends on both excitatory Na+ currents and inhibitory K+ and Cl? currents. During intensive exercise, active muscle loses K+ and extracellular K+ ([K+]o) increases. Since high [K+]o leads to depolarization and ensuing inactivation of voltage-gated Na+ channels and loss of excitability in isolated muscles, exercise-induced loss of K+ is likely to reduce muscle excitability and thereby contribute to muscle fatigue in vivo. Intensive exercise, however, also leads to muscle acidification, which recently was shown to recover excitability in isolated K+-depressed muscles of the rat. Here we show that in rat soleus muscles at 11 mM K+, the almost complete recovery of compound action potentials and force with muscle acidification (CO2 changed from 5 to 24%) was associated with reduced chloride conductance (1731 151 to 938 64 ?S/cm2, P < 0.01) but not with changes in potassium conductance (405 20 to 455 30 ?S/cm2, P < 0.16). Furthermore, acidification reduced the rheobase current by 26% at 4 mM K+ and increased the number of excitable fibers at elevated [K+]o. At 11 mM K+ and normal pH, a recovery of excitability and force similar to the observations with muscle acidification could be induced by reducing extracellular Cl? or by blocking the major muscle Cl? channel, ClC-1, with 30 ?M 9-AC. It is concluded that recovery of excitability in K+-depressed muscles induced by muscle acidification is related to reduction in the inhibitory Cl? currents, possibly through inhibition of ClC-1 channels, and acidosis thereby reduces the Na+ current needed to generate and propagate an AP. Thus short term regulation of Cl? channels is important for maintenance of excitability in working muscle. PMID:15684096

Pedersen, Thomas H.; de Paoli, Frank; Nielsen, Ole B.

2005-01-01

468

Female reproductive steroids and neuronal excitability.  

PubMed

Oestrogen and progesterone have specific receptors in the central nervous system and are able to regulate neuronal development and plasticity, neuronal excitability, mitochondrial energy production, and neurotransmitter synthesis, release, and transport. On neuronal excitability, estradiol and progesterone seem to have an opposite effect, with estradiol being excitatory and progesterone and its derivative allopregnanolone being inhibitory. Estradiol augments N-methyl-D-aspartate-mediated glutamate receptor activity, while progesterone enhances gamma-aminobutyric acid-mediated chloride conductance. Sex steroid regulation of the balance of neuroexcitatory and neuroinhibitory activities may have a role in modulating clinical susceptibility to different neurological conditions such as migraine, catamenial epilepsy, premenstrual dysphoric disorder, and premenstrual syndrome. PMID:21533709

Finocchi, C; Ferrari, M

2011-05-01

469

Bogoliubov Excited States and the Lyth Bound  

E-print Network

We show that Bogoliubov excited scalar and tensor modes do not alleviate Planckian evolution during inflation if one assumes that $r$ and the Bogoliubov coefficients are approximately scale invariant. We constrain the excitation parameter for the scalar fluctuations, $\\beta$, and tensor perturbations, $\\tilde{\\beta}$, by requiring that there be at least three decades of scale invariance in the scalar and tensor power spectrum. For the scalar fluctuations this is motivated by the observed nearly scale invariant scalar power spectrum. For the tensor fluctuations this assumption may be shown to be valid or invalid by future experiments.

Aditya Aravind; Dustin Lorshbough; Sonia Paban

2014-08-07

470

Laser pulses for coherent xuv Raman excitation  

E-print Network

We combine multi-channel electronic structure theory with quantum optimal control to derive Raman pulse sequences that coherently populate a valence excited state. For a neon atom, Raman target populations of up to 13% are obtained. Superpositions of the ground and valence Raman states with a controllable relative phase are found to be reachable with up to 4.5% population and phase control facilitated by the pump pulse carrier envelope phase. Our results open a route to creating core-hole excitations in molecules and aggregates that locally address specific atoms and represent the first step towards realization of multidimensional spectrosco