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1

Excitation energy after a smooth quench in a Luttinger liquid  

SciTech Connect

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

Dziarmaga, Jacek; Tylutki, Marek [Institute of Physics and Center for Complex Systems Research, Jagiellonian University, Reymonta 4, PL-30-059 Krakow (Poland)

2011-12-01

2

Equilibration of a spinless Luttinger liquid.  

SciTech Connect

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

Matveev, K. A.; Andreev, A. V. (Materials Science Division); (Univ. Washington)

2012-01-01

3

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

4

Junction of Tomonaga–Luttinger liquids  

Microsoft Academic Search

Low-energy physics of one-dimensional electron systems can be generally described in terms of the Tomonaga–Luttinger liquid, instead of the Fermi liquid. We give a nontechnical review for nonspecialists on this intriguing subject. As an example of physical consequences, we discuss junction of two and three Tomonaga–Luttinger liquids.

Masaki Oshikawa

2005-01-01

5

Equilibration of Luttinger liquid and conductance of quantum wires.  

SciTech Connect

Luttinger liquid theory describes one-dimensional electron systems in terms of noninteracting bosonic excitations. In this approximation thermal excitations are decoupled from the current flowing through a quantum wire, and the conductance is quantized. We show that relaxation processes not captured by the Luttinger liquid theory lead to equilibration of the excitations with the current and give rise to a temperature-dependent correction to the conductance. In long wires, the magnitude of the correction is expressed in terms of the velocities of bosonic excitations. In shorter wires it is controlled by the relaxation rate.

Matveev, K. A.; Andreev, A. V. (Materials Science Division); (Univ. of Washington)

2011-01-01

6

Electron lifetime in Luttinger liquids  

NASA Astrophysics Data System (ADS)

We investigate the decoherence of the electron wave packet in purely ballistic one-dimensional systems described through the Luttinger liquid (LL). At a finite temperature T and long times t , we show that the electron Green’s function for a fixed wave vector close to one Fermi point decays as exp(-t/?F) —as opposed to the power-law behavior occurring at short times—and the emerging electron lifetime obeys ?F-1?T for spinful as well as spinless electrons. For strong interactions, (T?F)?1 , reflecting that the electron is not a good Landau quasiparticle in LL’s. We justify that fractionalization is the main source of electron decoherence for spinful as well as spinless electrons clarifying the peculiar electron mass renormalization close to the Fermi points. For spinless electrons and weak interactions, our intuition can be enriched through a diagrammatic approach or Fermi golden rule and through a Johnson-Nyquist noise picture. We stress that the electron lifetime (and the fractional quasiparticles) can be revealed from Aharonov-Bohm experiments or momentum resolved tunneling. We aim to compare the results with those of spin-incoherent and chiral LL’s.

Le Hur, Karyn

2006-10-01

7

Relaxation processes in a disordered Luttinger liquid  

SciTech Connect

The Luttinger liquid model, which describes interacting electrons in a single-channel quantum wire, is completely integrable in the absence of disorder and as such does not exhibit any relaxation to equilibrium. We consider relaxation processes induced by inelastic electron-electron interactions in a disordered Luttinger liquid, focusing on the equilibration rate and its essential differences from the electron-electron scattering rate as well as the rate of phase relaxation. In the first part of the paper, we review the basic concepts in a disordered Luttinger liquid at equilibrium. These include the elastic renormalization, dephasing, and interference-induced localization. In the second part, we formulate a conceptually important framework for systematically studying the nonequilibrium properties of a strongly correlated (non-Fermi) Luttinger liquid. We derive a coupled set of kinetic equations for the fermionic and bosonic distribution functions that describe the evolution of a nonequilibrium Luttinger liquid. Remarkably, the energy equilibration rate in the conducting disordered quantum wire (at sufficiently high temperature, when the localization effects are suppressed by dephasing) is shown to be on the order of the rate of elastic scattering off disorder, independent of the interaction constant and temperature.

Bagrets, D. A.; Gornyi, I. V.; Mirlin, A. D.; Polyakov, D. G. [Forschungszentrum Karlsruhe, Institut fuer Nanotechnologie (Germany)], E-mail: polyakov@int.fzk.de

2008-08-15

8

Spin Dimers: from BEC to Luttinger liquids  

NASA Astrophysics Data System (ADS)

Localized spin systems, and in particular dimer systems, provide a fantastic laboratory to study the interplay between quantum effects and the interaction between excitations. Magnetic field and temperature allow an excellent control on the density of excitations and various very efficient probes such as neutrons and NMR are available. They can thus be used as "quantum simulators" to tackle with great success questions that one would normally search in itinerant interacting quantum systems. In particular they have provided excellent realizations of Bose-Einstein condensates [1,2]. This allowed not only to probe the properties of interacting bosons in a variety of dimensions but also to study in a controlled way additional effects such as disorder. If the dimensionality is reduced they also allow to test in a quantitative way Luttinger liquid physics [3,4,5]. I will discuss these various cases, and show that we have now good theoretical tools [6] to make quantitative comparisons with the experiments. Finally, how to go from this low dimensional case where the spins behave essentially as fermions, to the higher dimensional case where they behave as (essentially free) bosons, is a very challenging, and experimentally relevant issue.[4pt] [1] T. Giamarchi and A. Tsvelik, Phys. Rev. B 59 11398 (1999).[0pt] [2] T. Giamarchi, C. R"uegg and O. Tchernyshyov, Nat. Phys. 4 198 (2008).[0pt] [3] M. Klanjsek et al., Phys. Rev. Lett. 101 137207 (2008).[0pt] [4] C. R"uegg et al., Phys. Rev. Lett. 101 247202 (2008).[0pt] [5] B. Thielemann et al., Phys. Rev. B 79 020408(R) (2009).[0pt] [6] P. Bouillot et al., arXiv:1009.0840 (2010).

Giamarchi, Thierry

2011-03-01

9

Stability of Chiral Luttinger Liquids and Abelian Quantum Hall States  

NASA Astrophysics Data System (ADS)

A criterion is given for topological stability of Abelian quantum Hall states, and of Luttinger liquids at the boundaries between such states; this suggests a selection rule on states in the quantum Hall hierarchy theory. The linear response of Luttinger liquids to electromagnetic fields is described: the Hall conductance is quantized, irrespective of whether edge modes propagate in different directions.

Haldane, F. D. M.

1995-03-01

10

Spin current pumping in helical Luttinger liquids  

NASA Astrophysics Data System (ADS)

We study parametric quantum pumping in a two-dimensional topological insulator bar in the presence of electron interactions described by a helical Luttinger liquid. The pumping current is generated by two point contacts whose tunneling amplitudes are modulated in time. The helical nature of the edge states of the system ensures the generation of a pumped spin current that is determined by interference effects related to spin-flipping or spin-preserving tunneling at the quantum point contacts and which can be controlled by all electrical means. We show that the period of oscillation and the position of the zeros of the spin current depend on the strength of the electron interactions, giving the opportunity to directly extract information about them when measured.

Ferraro, D.; Dolcetto, G.; Citro, R.; Romeo, F.; Sassetti, M.

2013-06-01

11

Correlation functions of nonlinear Luttinger liquids as Fredholm determinants  

NASA Astrophysics Data System (ADS)

One dimensional quantum liquids are often described within an effective linear hydrodynamic approach known as Luttinger liquid theory. As the principal simplification, a generic spectrum of the constituent particles is replaced by a linear one, which leads to a linear hydrodynamic theory. It has been shown recently [1] that the nonlinearity of the generic spectrum leads to a significant modification of the dynamic response functions. Their description can be achieved within the universal framework of nonlinear Luttinger liquid theory. We show here that correlation functions within such approach can be expressed as Fredholm determinants, and evaluate them in low energy regions for arbitrary interaction strength and small temperatures. [4pt] [1] "Universal theory of nonlinear Luttinger liquids," A. Imambekov and L.I. Glazman, Science 323, 228 (2009)

Ma, Yinbin; Imambekov, Adilet

2011-03-01

12

Coupled Luttinger Liquid State in Quantum Hall Line Junction  

NASA Astrophysics Data System (ADS)

We report on tunneling spectroscopy of quantum Hall tunnel junctions that juxtaposes two counterpropagating edge states across a high quality tunnel barrier. As the only current-carrying excitation of quantum Hall effect, edge states possess a unique ability to form robust one-dimensional electronic state along the perimeter of two-dimensional electron system. In our tunnel junctions, produced by cleaved edge overgrowth, the two edge states are laterally separated by an in-plane semiconductor barrier on the order of magnetic length and interact strongly over a junction that is ˜100 ?m long. Due to the quality of the tunnel barrier and the ballistic property of the edge states, inter-edge electron-electron interaction effects become predominant and disorder plays a negligible role to the leading order. Tunneling strongly mix the single particle states from two chiral one-dimensional systems, and the inter- edge correlation transforms the two counterpropagating edge states into a system of coupled, non- chiral Luttinger liquid whose Luttinger liquid properties are continuously tuned by magnetic field through the filling factor ? of the bulk quantum Hall state. The tunneling density of states of this many-body state possesses a power- law dependence on energy with an exponent ?, that is inversely proportional to the bulk filling factor, ?˜1/?. Inter-edge correlation also manifests in a series of quantum critical points between successive strong and weak tunneling regimes that are reminiscent of the plateau-transitions in quantum Hall effect. Tunneling spectroscopy consequently provides a direct probe of the quantum order underlying within these highly correlated one-dimensional states.

Yang, Inseok

2006-03-01

13

Luttinger liquid behavior in single-wall nanotubes  

NASA Astrophysics Data System (ADS)

Transport properties of metallic single-wall nanotubes are examined based on the Luttinger liquid theory. Focusing on a nanotube transistor setup, the linear conductance is computed from the Kubo formula using perturbation theory in the lead-tube tunnel conductances. For sufficiently long nanotubes and high temperature, phonon backscattering should lead to an anomalous temperature dependence of the resistivity.

Komnik, Andrei; Egger, Reinhold

1999-09-01

14

a Luttinger Liquid Core Inside HELIUM-4 Filled Nanopores  

NASA Astrophysics Data System (ADS)

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

Del Maestro, Adrian

2012-09-01

15

Numerical evidence of Luttinger liquid behavior of potassium doped trans-polyacetylene chain of infinite length  

Microsoft Academic Search

We report on the first direct numerical evidence of a Tomonaga–Luttinger liquid behavior in potassium doped trans-polyacetylene system and a possible deviation from Tomonaga–Luttinger liquid state at very high doping concentration. Using density functional theoretical calculation, an analysis of density of states near the Fermi energy reveals a power law scaling factor of Tomonaga–Luttinger liquid at low dopant concentration in

Sabyasachi Sen; Swapan Chakrabarti

2006-01-01

16

Numerical evidence of Luttinger liquid to Fermi liquid transformation in lithium doped trans-polyacetylene chain  

Microsoft Academic Search

We report on the first direct numerical evidence of doping-induced transformation of Tomonaga–Luttinger liquid to Fermi liquid in quasi-one-dimensional lithium doped trans-polyacetylene chain. Using density functional theoretical calculation, an analysis of density of states near the Fermi energy reveals a power-law scaling factor of Tomonaga–Luttinger liquid at low dopant concentration in the metallic regime. As soon as the doping level

Sabyasachi Sen; Swapan Chakrabarti

2007-01-01

17

Dynamics of a heavy particle in a Luttinger liquid  

NASA Astrophysics Data System (ADS)

We study the dynamics of a heavy particle of mass M moving in a one-dimensional repulsively interacting Fermi gas. The Fermi gas is described using the Luttinger model and bosonization. By transforming to a frame comoving with the heavy particle, we map the model onto a generalized ``quantum impurity problem.'' A renormalization-group calculation reveals a crossover from strong to weak coupling upon scaling down in temperature. Above the crossover temperature scale T*=(m/M)EF, the particle's mobility ? is found to be (roughly) temperature independent and proportional to the dimensionless conductance g, characterizing the one-dimensional Luttinger liquid. Here m(<0 limit.

Castro Neto, A. H.; Fisher, Matthew P. A.

1996-04-01

18

Dynamics of a heavy particle in a Luttinger liquid  

NASA Astrophysics Data System (ADS)

We study the dynamics of a heavy particle of mass M moving in a one-dimensional repulsively interacting Fermi gas. The Fermi gas is described using the Luttinger model and bosonization. By transforming to a frame co-moving with the heavy particle, we map the model onto a generalized ``quantum impurity problem". A renormalization group calculation reveals a crossover from strong to weak coupling upon scaling down in temperature. Above the crossover temperature scale T = (m/M)E_F, the particle's mobility, ?, is found to be (roughly) temperature independent and proportional to the dimensionless conductance, g, characterizing the 1d Luttinger liquid. Here m (<

Castro Neto, Antonio H.; Fisher, Matthew P. A.

1996-03-01

19

Phase transitions for a collective coordinate coupled to luttinger liquids.  

PubMed

We study various realizations of collective coordinates, e.g., the position of a particle, the charge of a Coulomb box, or the phase of a Bose or a superconducting condensate, coupled to Luttinger liquids with N flavors. We find that for a Luttinger parameter (1/2)

Horovitz, Baruch; Giamarchi, Thierry; Le Doussal, Pierre

2013-09-09

20

Nonequilibrium transport of helical Luttinger liquids through a quantum dot  

NASA Astrophysics Data System (ADS)

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

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

2013-08-01

21

Correlations in nonequilibrium Luttinger liquid and singular Fredholm determinants.  

PubMed

We study interaction-induced correlations in Luttinger liquid with multiple Fermi edges. Many-particle correlation functions are expressed in terms of Fredholm determinants det(1+ÂB[over ^]), where A(?) and B(t) have multiple discontinuities in energy and time spaces. We propose a general asymptotic formula for this class of determinants and provide analytical and numerical support to this conjecture. This allows us to establish nonequilibrium Fermi-edge singularities of many-particle correlation functions. As an example, we calculate a two-particle distribution function characterizing genuinely nonequilibrium quantum correlations between left- and right-moving fermions that have left the interaction region. PMID:23745901

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

2013-05-22

22

Aharonov-Bohm effect in the chiral Luttinger liquid  

NASA Astrophysics Data System (ADS)

Edge states of the quantum Hall fluid provide an almost unparalled opportunity to study mesoscopic effects in a highly correlated electron system. In this paper we develop a bosonization formalism for the finite-size edge state, as described by chiral Luttinger liquid theory, and use it to study the Aharonov-Bohm effect. The problem we address may be realized experimentally by measuring the tunneling current between two edge states through a third edge state formed around an antidot in the fractional quantum Hall effect regime. The finite size L of the antidot edge state introduces a temperature scale T0??v/?kBL, where v is the edge-state Fermi velocity. A renormalization group analysis reveals the existence of a two-parameter universal scaling function G~(X,Y) that describes the Aharonov-Bohm conductance resonances. We also show that the strong renormalization of the tunneling amplitudes that couple the antidot to the incident edge states, together with the nature of the Aharonov-Bohm interference process in a chiral system, prevent the occurrence of perfect resonances as the magnetic field is varied, even at zero temperature. In an experimentally realizable strong-antidot-coupling regime, where the source-to-drain transmission is weak, and at bulk filling factor g=1/q with q an odd integer, we predict the low-temperature (T<liquid (q=1). Near T0, there is a pronounced maximum in the amplitude, also in contrast to a Fermi liquid. At high temperatures (T>>T0), however, we predict a crossover to a T2q-1e-qT/T0 temperature dependence, which is qualitatively similar to chiral Fermi liquid behavior. Careful measurements in the strong-antidot-coupling regime above T0 should be able to distinguish between a Fermi liquid and our predicted nearly Fermi liquid scaling. In addition, we predict an interesting high-temperature nonlinear response regime, where the voltage satisfies V>T>T0, which may also be used to distinguish between chiral Fermi liquid and chiral Luttinger liquid behavior. Finally, we predict mesoscopic edge-current oscillations, which are similar to the persistent current oscillations in a mesoscopic ring, except that they are not reduced in amplitude by weak disorder. In the fractional quantum Hall effects regime, these ``chiral persistent currents'' have a universal non-Fermi-liquid temperature dependence and may be another ideal system to observe a chiral Luttinger liquid.

Geller, Michael R.; Loss, Daniel

1997-10-01

23

Impurities in magnetic-field-induced Luttinger liquid  

NASA Astrophysics Data System (ADS)

It has been shown recently(C. Biagini, D. L. Maslov, M. Yu. Reizer and L. I. Glazman, `` Magnetic-field-induced Luttinger liquid''), cond-mat/0006407. that a strong magnetic field applied to a bulk metal may induce a Luttinger liquid phase. This is a consequence of the reduced effective dimensionality of charge carriers from 3D to 1D, an effect which is most pronounced in the ultra-quantum limit, when only the lowest Landau level remains populated. We study the effect of impurities in this system. For the case of a point impurity, the calculation of the scattering cross section at a single impurity can be mapped exactly to a 1D problem of tunneling conductance through a barrier for interacting electrons, solved by Yue et al.(D. Yue, L. I. Glazman and K. A. Matveev, Phys. Rev. B 49) (1994) 1966.. Using this mapping, we find that the longitudinal (?=+1) and transverse (?=-1) Drude conductivities exhibit the scaling laws ?_?? T^??, where ?=2e^2|ln?l_B|/? v_F, and vF and ? are the B-dependent Fermi velocity and screening wavevector, respectively; lB is the magnetic length. The physical reason for such a behavior of the conductivity is the almost 1D form of the Friedel oscillation around a single point impurity in the strong magnetic field.

Tsai, Shan-Wen; Maslov, Dmitrii L.; Glazman, Leonid I.

2001-03-01

24

Chiral Luttinger liquids and a generalized Luttinger theorem in fractional quantum Hall edges via finite-entanglement scaling  

NASA Astrophysics Data System (ADS)

We use bosonic field theories and the infinite system density matrix renormalization group method to study infinite strips of fractional quantum Hall states starting from microscopic Hamiltonians. Finite-entanglement scaling allows us to accurately measure chiral central charge, edge-mode exponents, and momenta without finite-size errors. We analyze states in the first and second levels of the standard hierarchy and compare our results to predictions of the chiral Luttinger liquid theory. The results confirm the universality of scaling exponents in chiral edges and demonstrate that renormalization is subject to universal relations in the nonchiral case. We prove a generalized Luttinger theorem involving all singularities in the momentum-resolved density, which naturally arises when mapping Landau levels on a cylinder to a fermion chain and deepens our understanding of non-Fermi liquids in one dimension.

Varjas, Dániel; Zaletel, Michael P.; Moore, Joel E.

2013-10-01

25

Rectification in Y-junctions of Luttinger liquid wires  

NASA Astrophysics Data System (ADS)

We investigate rectification of a low-frequency ac bias in Y-junctions of one-channel Luttinger liquid wires with repulsive electron interaction. Rectification emerges due to three scatterers in the wires. We find that it is possible to achieve a higher rectification current in a Y-junction than in a single wire with an asymmetric scatterer at the same interaction strength and voltage bias. The rectification effect is the strongest in the absence of the time-reversal symmetry. In that case, the maximal rectification current can be comparable to the total current ~e2V/h even for low voltages, weak scatterers, and modest interaction strength. In a certain range of low voltages, the rectification current can grow as the voltage decreases. This leads to a bump in the I-V curve.

Wang, Chenjie; Feldman, D. E.

2011-01-01

26

Coherence and Localization in 2D Luttinger Liquids  

SciTech Connect

Recent measurements on the resistivity of (La-Sr){sub 2}CuO{sub 4} are shown to fit within the general framework of Luttinger liquid transport theory. They exhibit a crossover from the spin-charge separated {open_quote}{open_quote}holon nondrag regime{close_quote}{close_quote} usually observed, with {rho}{sub {ital ab}}{approximately}{ital T}, to a {open_quote}{open_quote}localizing{close_quote}{close_quote} regime dominated by impurity scattering at low temperature. The proportionality of {rho}{sub {ital c}} and {rho}{sub {ital ab}} and the giant anisotropy follow directly from the theory. {copyright} {ital 1996 The American Physical Society.}

Anderson, P.W.; Ramakrishnan, T.V.; Strong, S.; Clarke, D.G. [Department of Physics, Jadwin Hall, Princeton University, Princeton, New Jersey 08544 (United States)]|[Department of Physics, Indian Institute of Science, Bangalore, 560 012 (India)]|[NEC Research, 4 Independence Way, Princeton, New Jersey 08540 (United States)]|[TCM, Cavendish Laboratory, Madingley Road, Cambridge, CB3 0HE (England)

1996-11-01

27

Entanglement entropy between two coupled Tomonaga-Luttinger liquids  

SciTech Connect

We consider a system of two coupled Tomonaga-Luttinger liquids (TLL's) on parallel chains and study the Renyi entanglement entropy S{sub n} between the two chains. Here the entanglement cut is introduced between the chains, not along the perpendicular direction, as has been done in previous studies of one-dimensional systems. The limit n{yields}1 corresponds to the von Neumann entanglement entropy. The system is effectively described by two-component bosonic field theory with different TLL parameters in the symmetric and antisymmetric channels as far as the coupled system remains in a gapless phase. We argue that in this system, S{sub n} is a linear function of the length of the chains (boundary law) followed by a universal subleading constant {gamma}{sub n} determined by the ratio of the two TLL parameters. The formulas of {gamma}{sub n} for integer n{>=}2 are derived using (a) ground-state wave functionals of TLL's and (b) boundary conformal field theory, which lead to the same result. These predictions are checked in a numerical diagonalization analysis of a hard-core bosonic model on a ladder. Although the analytic continuation of {gamma}{sub n} to n{yields}1 turns out to be a difficult problem, our numerical result suggests that the subleading constant in the von Neumann entropy is also universal. Our results may provide useful characterization of inherently anisotropic quantum phases such as the sliding Luttinger liquid phase via qualitatively different behaviors of the entanglement entropy with the entanglement partitions along different directions.

Furukawa, Shunsuke [Department of Physics, University of Toronto, Toronto, Ontario, M5S 1A7 (Canada); Kim, Yong Baek [Department of Physics, University of Toronto, Toronto, Ontario, M5S 1A7 (Canada); School of Physics, Korea Institute for Advanced Study, Seoul 130-722 (Korea, Republic of)

2011-02-15

28

Aharonov-Bohm Effect in the Chiral Luttinger Liquid  

NASA Astrophysics Data System (ADS)

I will discuss recent work done with Daniel Loss and George Kirczenow on the Aharonov-Bohm effect in the fractional quantum Hall regime with chiral-Luttinger-liquid edge states.(M. R. Geller, D. Loss, and G. Kirczenow, Phys. Rev. Lett. 77), 5110 (1996). The problem we address is realized experimentally by measuring the tunneling current between two fractional edge states through a third edge state formed around an antidot. The finite size of the antidot edge state introduces a temperature scale T0 ? hbar v / ? kB L, where v is the edge-state Fermi velocity and L is the length of the antidot edge state. For example, v=10^6 cm/s and L=1 ? m yield T0 ? 25 mK. In an experimentally realizable strong-antidot-coupling regime, where the source-to-drain transmission is weak, and at bulk filling factor g = 1/q with q an odd integer, we predict the low-temperature (T << T_0) Aharonov-Bohm amplitude to vanish with temperature as T^2q-2, in striking contrast to a Fermi liquid (q=1). Near T_0, there is a pronounced maximum in the amplitude, also in contrast to a Fermi liquid. At high temperatures (T >> T_0), however, we predict a crossover to a T^2q-1 e^-q T/T0 temperature dependence, which is qualitatively similar to chiral Fermi liquid behavior. Careful measurements in the strong-antidot-coupling regime above T0 should be able to distinguish between a Fermi liquid and our predicted nearly Fermi-liquid scaling. In addition, we predict an interesting high-temperature nonlinear response regime, where the voltage satisfies V > T > T_0, which may also be used to distinguish between Fermi and Luttinger liquids. I will also discuss the tunneling in the weak-antidot-coupling case, which turns out to be considerably different than the weak tunneling regime of the related quantum-point-contact system.

Geller, Michael R.

1997-03-01

29

Luttinger liquid fixed point for a two-dimensional flat Fermi surface  

NASA Astrophysics Data System (ADS)

We consider a system of two-dimensional interacting fermions with a flat Fermi surface. The apparent conflict between Luttinger and non-Luttinger liquid behaviors found through different approximations is resolved by showing the existence of a line of nontrivial fixed points, for the renormalization group (RG) flow, corresponding to Luttinger liquid behavior; the presence of marginally relevant operators can cause flow away from the fixed point. The analysis is nonperturbative and based on the implementation, at each RG iteration, of Ward identities obtained from local phase transformations depending on the Fermi surface side, implying the partial vanishing of the beta function.

Mastropietro, Vieri

2008-05-01

30

Tomonaga-Luttinger parameters and spin excitations in the dimerized extended Hubbard model  

Microsoft Academic Search

We study the one-dimensional extended Hubbard model with alternating size of the hopping integrals using the density-matrix renormalization group method. We calculate the spin gap, the Tomonaga-Luttinger parameter, and the charge-density-wave order parameter for various dimerizations, interaction strengths, and band fillings. At half band-filling the spin and charge excitations are gapped but these gaps disappear for infinitesimal hole doping. At

Satoshi Ejima; Florian Gebhard; Satoshi Nishimoto

2006-01-01

31

Transport Through Luttinger Liquids: The Role of Fermi-Liquid Reservoirs  

Microsoft Academic Search

The conductance G of one-dimensional Luttinger liquids (LLs) has commonly been believed to exhibit two features: (i) in a perfect LL, the electron-electron interactions renormalize G to the value of Ke^2\\/h, where K depends on the sign and the strength of interactions; (ii) in the presence of weak disorder, G exhibits characteristic temperature- or length-scalings. However, a recent experiment on

Dmitrii L. Maslov

1996-01-01

32

Tunneling spectroscopy of a spiral Luttinger liquid in contact with superconductors  

NASA Astrophysics Data System (ADS)

One-dimensional wires with Rashba spin-orbit coupling, magnetic field, and strong electron-electron interactions are described by a spiral Luttinger liquid model. We develop a theory to investigate the tunneling density of states into a spiral Luttinger liquid under the proximity effect with superconductors. This approach provides a way to disentangle the delicate interplay between superconducting correlations and strong electron interactions. If the wire-superconductor boundary is dominated by Andreev reflection, we find that in the vicinity of the interface the zero-bias tunneling anomaly reveals a power law enhancement with the unusual exponent. Far away from the interface strong correlations inherent to the Luttinger liquid prevail and restore conventional suppression of the tunneling density of states at the Fermi level, which acquire, however, a Friedel-like oscillatory envelope with the period renormalized by the strength of the interaction.

Liu, Dong E.; Levchenko, Alex

2013-10-01

33

Doped spin liquid: Luttinger sum rule and low temperature order.  

PubMed

We analyze a model of two-leg Hubbard ladders weakly coupled by interladder tunneling. At half filling a semimetallic state with small Fermi pockets is induced beyond a threshold tunneling strength. The sign changes in the single electron Green's function relevant for the Luttinger sum rule now take place at surfaces with both zeros and infinities with important consequences for the interpretation of angle-resolved photoemission spectroscopy experiments. Residual interactions between electron and holelike quasiparticles cause a transition to long range order at low temperatures. The theory can be extended to small doping leading to superconducting order. PMID:16606208

Konik, R M; Rice, T M; Tsvelik, A M

2006-03-03

34

Ground-state properties of one-dimensional matter and quantum dissociation of a Luttinger liquid  

NASA Astrophysics Data System (ADS)

Motivated by emerging experimental possibilities to confine atoms and molecules in quasi-one-dimensional geometries, we analyze ground-state properties of strictly one-dimensional molecular matter comprised of identical particles of mass m. Such a class of systems can be described by an additive two-body potential whose functional form is common to all substances which only differ in the energy ? and range l scales of the potential. With this choice De Boer’s quantum theorem of corresponding states holds and the ground-state properties expressed in appropriate reduced form are only determined by the dimensionless parameter ?20˜?2/ml2?, measuring the strength of zero-point motion in the system. The presence of a minimum in the two-body interaction potential leads to a many-body bound state which is a Luttinger liquid stable for not very large ?0. As ?0 increases, the asymmetry of the two-body potential causes quantum expansion, softening, and eventual evaporation of the Luttinger liquid into a gas phase. Selecting the pair interaction potential in the Morse form we analytically compute the properties of the Luttinger liquid and its range of existence. We find that as ?0 increases, the system first undergoes a discontinuous evaporation transition into a diatomic gas followed by a continuous dissociation transition into a monoatomic gas. In particular we find that spin-polarized isotopes of hydrogen and 3He are monoatomic gases, 4He is a diatomic gas, while molecular hydrogen and heavier substances are Luttinger liquids. We also investigate the effect of finite pressure on the properties of the liquid- and monoatomic gas phases. In particular we estimate a pressure at which molecular hydrogen undergoes an inverse Peierls transition into a metallic state which is a one-dimensional analog of the transition predicted by Wigner and Huntington in 1935 [E. Wigner and H.B. Huntington, J. Chem Phys. 3, 764 (1935)].

Kolomeisky, Eugene B.; Qi, Xiaoya; Timmins, Michael

2003-04-01

35

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

NASA Astrophysics Data System (ADS)

Based on the NMR measurements on Bi2Sr2-xLaxCuO6+? (La-Bi2201) in strong magnetic fields, we identify the nonsuperconducting pseudogap phase in the cuprates as a Luttinger-volume violating Fermi liquid (LvvFL). This state is a zero-temperature quantum liquid that does not break translational symmetry, and yet, the Fermi surface encloses a volume smaller than the large one given by the Luttinger theorem. The particle number enclosed by the small Fermi surface in the LvvFL equals the doping level p, not the total electron number ne=1-p. Both the phase string theory and the dopon theory are introduced to describe the LvvFL. For the dopon theory, we can obtain a semiquantitative agreement with the NMR experiments.

Mei, Jia-Wei; Kawasaki, Shinji; Zheng, Guo-Qing; Weng, Zheng-Yu; Wen, Xiao-Gang

2012-04-01

36

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

37

Spin-polarized scanning-tunneling probe for helical Luttinger liquids.  

PubMed

We propose a three-terminal spin-polarized STM setup for probing the helical nature of the Luttinger liquid edge state that appears in the quantum spin Hall system. We show that the three-terminal tunneling conductance depends on the angle (?) between the magnetization direction of the tip and the local orientation of the electron spin on the edge while the two terminal conductance is independent of this angle. We demonstrate that chiral injection of an electron into the helical Luttinger liquid (when ? is zero or ?) is associated with fractionalization of the spin of the injected electron in addition to the fractionalization of its charge. We also point out a spin current amplification effect induced by the spin fractionalization. PMID:21770527

Das, Sourin; Rao, Sumathi

2011-06-10

38

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

PubMed

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

Schuricht, D; Andergassen, S; Meden, V

2012-12-05

39

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

NASA Astrophysics Data System (ADS)

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

Schuricht, D.; Andergassen, S.; Meden, V.

2013-01-01

40

Transport Through Luttinger Liquids: The Role of Fermi-Liquid Reservoirs  

NASA Astrophysics Data System (ADS)

The conductance G of one-dimensional Luttinger liquids (LLs) has commonly been believed to exhibit two features: (i) in a perfect LL, the electron-electron interactions renormalize G to the value of Ke^2/h, where K depends on the sign and the strength of interactions; (ii) in the presence of weak disorder, G exhibits characteristic temperature- or length-scalings. However, a recent experiment on ultra-clean GaAs quantum wires(S. Tarucha, T. Honda, and T. Saku, Solid State Comm. 94), 413 (1995). has revealed only the LL-like temperature dependence of G, but no renormalization of G in the ballistic limit (i.e., K=1). In this work, we explore the consequences of the fact that in a typical experiment a LL quantum wire is attached to the wide Fermi-liquid (FL) leads. In particular, it is shown that the dc conductance of a LL wire with FL leads is given by e^2/h, regardless of the interactions in the wire.(D. L. Maslov and M. Stone, Phys. Rev. B52), R5539 (1995). On the other hand, the temperature- and length-dependent corrections are determined by the interactions in the wire.(D. L. Maslov, Phys. Rev. B52), R14368 (1995). These results suggest that the experimental observations by Tarucha et al. can indeed be considered as an indication of the Luttinger-liquid state in GaAs quantum wires. The recently observed crossover from the LL- to the FL-behavior as the number of propagating channels is increased(S. Tarucha, T. Honda, T. Saku, and Y. Tokura (unpublished).) is also discussed. Parts of this work were performed in collaboration with Michael Stone and Nancy Sandler. This work was supported by the National Science Foundation through grants DMR94-24511 and DMR89-20538.

Maslov, Dmitrii L.

1996-03-01

41

Entanglement entropy and quantum phase transitions in quantum dots coupled to Luttinger liquid wires  

NASA Astrophysics Data System (ADS)

We study a quantum phase transition that occurs in a system composed of two impurities (or quantum dots), each coupled to a different interacting (Luttinger liquid) lead. While the impurities are coupled electrostatically, there is no tunneling between them. Using a mapping of this system onto a Kondo model, we show analytically that the system undergoes a Berezinskii-Kosterlitz-Thouless quantum phase transition as a function of the Luttinger liquid parameter in the leads and the dot-lead interaction. The phase with low values of the Luttinger liquid parameter is characterized by an abrupt switch of the population between the impurities as a function of a common applied gate voltage. However, this behavior is hard to verify numerically since one would have to study extremely long systems. Interestingly, though, at the transition the entanglement entropy drops from a finite value of ln(2) to zero. The drop becomes sharp for infinite systems. One can employ finite-size scaling to extrapolate the transition point and the behavior in its vicinity from the behavior of the entanglement entropy in moderate size samples. We employ the density matrix renormalization-group numerical procedure to calculate the entanglement entropy of systems with lead lengths of up to 480 sites. Using finite-size scaling, we extract the transition value and show it to be in good agreement with the analytical prediction.

Goldstein, Moshe; Gefen, Yuval; Berkovits, Richard

2011-06-01

42

Evidence of Luttinger-liquid behavior in one-dimensional dipolar quantum gases  

SciTech Connect

A strongly correlated Luttinger-liquid behavior is found to emerge well beyond the Tonks-Girardeau (TG) regime in a one-dimensional Bose gas with dipolar repulsions at T=0, persisting for a wide range of densities. After combining reptation quantum Monte Carlo and bosonization techniques, we provide a unifying theory of the underlying crossover physics, evolving from the TG gas at low density into a classical quasiordered state at high density. The density dependent Luttinger parameters extracted from the numerical data provide all that is needed to determine the low-energy behavior from analytical expressions. Our quantitative predictions, in the whole crossover, for measurable quantities such as the structure factor and the momentum distribution, are estimated to be accessible in underway experiments with ultracold polar molecules.

Citro, R. [Dipartimento di Fisica E. R. Caianiello and CNISM, Universita degli Studi di Salerno, Salerno (Italy); Orignac, E. [Laboratoire de Physique de l'Ecole Normale, Superieure de Lyon, CNRS-UMR5672, Lyon (France); De Palo, S. [DEMOCRITOS INFM-CNR and Dipartimento di Fisica Teorica, Universita Trieste, Trieste (Italy); Chiofalo, M. L. [Classe di Scienze, INFN and CNISM, Scuola Normale Superiore, Pisa (Italy)

2007-05-15

43

Field-controlled Luttinger liquid and possible crossover into spin liquid in strong-rail ladder systems.  

PubMed

The thermodynamics and transport properties of strong-rail ladder systems are investigated by means of Green's function theory. It is shown that the magnetic behavior clearly manifests a typical antiferromagnetism with gapped or gapless low-lying excitations, which is in agreement with the experimental results. In addition, the temperature-field-induced phase diagram is explored, and we demonstrate a Luttinger liquid behavior in the window h(c) (marking the ending of the M=0 plateau)liquid phase is uncovered for h

Ding, Lin-Jie; Yao, Kai-Lun; Fu, Hua-Hua

2010-10-25

44

Microwave-induced forward scattering and Luttinger liquid interferences in magnetically confined quantum wires  

NASA Astrophysics Data System (ADS)

We report on the photoresistance of a magnetic quantum wire obtained by applying a gradient of magnetic field to a two-dimensional electron gas. Electron transmission through the magnetic wire increases by an order of magnitude under microwave irradiation and exhibits frequency-dependent magneto-oscillations as a function of the in-plane magnetic field. Both results are fully consistent with microwave-coupled Luttinger liquid edge channels which interfere at two pinning sites in the fashion of a Mach-Zehnder interferometer.

Nogaret, A.; Portal, J.-C.; Beere, H. E.; Ritchie, D. A.; Phillips, C.

2008-10-01

45

Luttinger liquid and polaronic effects in electron transport through a molecular transistor  

NASA Astrophysics Data System (ADS)

Electron transport through a single-level quantum dot weakly coupled to Luttinger liquid leads is considered in the master equation approach. It is shown that for a weak or moderately strong interaction the differential conductance demonstrates resonant-like behavior as a function of bias and gate voltages. The inelastic channels associated with vibron-assisted electron tunneling can even dominate electron transport for a certain region of interaction strength. In the limit of strong interaction resonant behavior disappears and the differential conductance scales as a power law in temperature (linear regime) or in bias voltage (nonlinear regime).

Skorobagat'ko, G. A.; Krive, I. V.

2008-10-01

46

Thermodynamics of the spin Luttinger liquid in a model ladder material.  

PubMed

The phase diagram in temperature and magnetic field of the metal-organic, two-leg, spin-ladder compound (C5H12N)2CuBr4 is studied by measurements of the specific heat and the magnetocaloric effect. We demonstrate the presence of an extended spin Luttinger-liquid phase between two field-induced quantum critical points and over a broad range of temperature. Based on an ideal spin-ladder Hamiltonian, comprehensive numerical modeling of the ladder specific heat yields excellent quantitative agreement with the experimental data across the entire phase diagram. PMID:19113659

Rüegg, Ch; Kiefer, K; Thielemann, B; McMorrow, D F; Zapf, V; Normand, B; Zvonarev, M B; Bouillot, P; Kollath, C; Giamarchi, T; Capponi, S; Poilblanc, D; Biner, D; Krämer, K W

2008-12-10

47

Tomonaga-Luttinger liquid features in ballistic single-walled carbon nanotubes: conductance and shot noise.  

PubMed

We study the electrical transport properties of well-contacted ballistic single-walled carbon nanotubes in a three-terminal configuration at low temperatures. We observe signatures of strong electron-electron interactions: the conductance exhibits bias-voltage-dependent amplitudes of quantum interference oscillation, and both the current noise and Fano factor manifest bias-voltage-dependent power-law scalings. We analyze our data within the Tomonaga-Luttinger liquid model using the nonequilibrium Keldysh formalism and find qualitative and quantitative agreement between experiment and theory. PMID:17678308

Kim, Na Young; Recher, Patrik; Oliver, William D; Yamamoto, Yoshihisa; Kong, Jing; Dai, Hongjie

2007-07-17

48

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

NASA Astrophysics Data System (ADS)

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

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

2013-01-01

49

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

PubMed

We report experimental results for the changes in conductivity of single-wall carbon nanotube bundles when irradiated by (60)Co ?-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 × 10(7) rad in vacuum, 1.7 × 10(7) rad in hydrogen and 1.24 × 10(8) rad in deuterium. PMID:24172218

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

2013-10-31

50

Cluster Luttinger Liquids of Rydberg-Dressed Atoms in Optical Lattices  

NASA Astrophysics Data System (ADS)

We investigate the zero-temperature phases of bosonic and fermionic gases confined to one dimension and interacting via a class of finite-range soft-shoulder potentials (i.e., soft-core potentials with an additional hard-core onsite interaction). Using a combination of analytical and numerical methods, we demonstrate the stabilization of critical quantum liquids with qualitatively new features with respect to the Tomonaga-Luttinger liquid paradigm. These features result from frustration and cluster formation in the corresponding classical ground state. Characteristic signatures of these liquids are accessible in state-of-the-art experimental setups with Rydberg-dressed ground-state atoms trapped in optical lattices.

Mattioli, Marco; Dalmonte, Marcello; Lechner, Wolfgang; Pupillo, Guido

2013-10-01

51

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

PubMed

Using micromechanical force magnetometry, we have measured the magnetization of the strong-leg spin-1/2 ladder compound (C(7)H(10)N)(2)CuBr(2) at temperatures down to 45 mK. Low-temperature magnetic susceptibility as a function of field exhibits a maximum near the critical field H(c) at which the magnon gap vanishes, as expected for a gapped one-dimensional antiferromagnet. Above H(c) a clear minimum appears in the magnetization as a function of temperature, as predicted by theory. In this field region, the susceptibility in conjunction with our specific-heat data yields the Wilson ratio R(W). The result supports the relation R(W)=4K, where K is the Tomonaga-Luttinger-liquid parameter. PMID:22463663

Ninios, K; Hong, Tao; Manabe, T; Hotta, C; Herringer, S N; Turnbull, M M; Landee, C P; Takano, Y; Chan, H B

2012-02-27

52

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

PubMed

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

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

2013-07-23

53

Wilson Ratio of a Tomonaga-Luttinger Liquid in a Spin-1/2 Heisenberg Ladder  

SciTech Connect

Using micromechanical force magnetometry, we have measured the magnetization of the strongleg spin-1/2 ladder compound (C7H10N)2CuBr2 at temperatures down to 45 mK. Low-temperature magnetic susceptibility as a function of field exhibits a maximum near the critical field Hc at which the magnon gap vanishes, as expected for a gapped one-dimensional antiferromagnet. Above Hc a clear minimum appears in the magnetization as a function of temperature as predicted by theory. In this field region, the susceptibility in conjunction with our specific heat data yields the Wilson ratio RW. The result supports the relation RW = 4K, where K is the Tomonaga-Luttinger-liquid parameter.

Ninios, K [University of Florida, Gainesville; Hong, Tao [ORNL; Manabe, T. [Kyoto Sangyo University; Hotta, C. [Kyoto Sangyo University; Herringer, S. N. [Clark University; Turnbull, M. M. [Clark University; Landee, C. [Clark University; Takano, Y. [University of Florida, Gainesville; Chan, H. B. [Hong Kong University of Science & Technology

2012-01-01

54

Loschmidt Echo and the Many-Body Orthogonality Catastrophe in a Qubit-Coupled Luttinger Liquid  

NASA Astrophysics Data System (ADS)

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

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

2013-07-01

55

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

NASA Astrophysics Data System (ADS)

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

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

2013-03-01

56

Non-Fermi-Liquid Single Particle Line Shape of the Quasi-One-Dimensional Non-CDW Metal Li{sub 0.9}Mo{sub 6}O{sub 17} : Comparison to the Luttinger Liquid  

SciTech Connect

We report the detailed non-Fermi-liquid (NFL) line shape of the dispersing excitation which defines the Fermi surface for quasi-one-dimensional Li{sub 0.9}Mo {sub 6}O{sub 17} . The properties of Li{sub 0.9}Mo {sub 6}O{sub 17} strongly suggest that the NFL behavior has a purely electronic origin. In relation to the theoretical Luttinger liquid line shape, we identify significant similarities, but also important differences. {copyright} {ital 1999} {ital The American Physical Society}

Denlinger, J.D.; Gweon, G.; Allen, J.W.; Schlenker, C.; Hsu, L. [Randall Laboratory of Physics, University of Michigan, Ann Arbor, Michigan 48109-1120 (United States); Olson, C.G. [Ames Laboratory, Iowa State University, Ames, Iowa 50011 (United States); Marcus, J. [Laboratoire d`Etudes des Proprietes Electroniques des Solides--CNRS, BP166, 38042 Grenoble Cedex (France)

1999-03-01

57

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

58

Quantized Conductance of GaAs Quantum Wires: Signature of the Luttinger-Liquid Behavior  

NASA Astrophysics Data System (ADS)

Strong mutual Coulomb interactions in a dilute one-dimensional electron system can give rise to a particular non-Fermi-liquid phase, referred to as a Tomonaga- Luttinger (T-L) liquid. We investigate the effect of mutual Coulomb interactions on the breakdown of quantized conductance in long quantum wires. We fabricate quantum wires with a novel side gate geometry from a very high mobility modulation-doped heterostructure, and observe a small but definite decrease in the quantized conductance at low temperature(S. Tarucha, T. Honda, T. Saku, Sol. State Commun. 94, 413 (1995).). The temperature dependence is reproduced by the power-law predicted in the theory for a T-L liquid in the presence of random potential scattering( M. Ogata and H. Fukuyama, Phys. Rev. Lett. 73, 468 (1994).). The conductance at higher temperatures is not renormalized by the correlation exponent. This is explained by the existence of wide electron reservoirs( D. L. Maslov and M. Stone Rhys. Rev. B52, R5539 (1995).). We also observe that the temperature dependence becomes weak when more than one subbands are occupied in the quantum wire. This is also related to the reduced effect of mutual Coulomb interactions in a many mode system.

Tarucha, S.

1996-03-01

59

Helium-4 crossover from a 3d superfluid to a 1d Luttinger liquid in a nanopore  

NASA Astrophysics Data System (ADS)

Quantum Monte Carlo studies of helium-4 below the bulk superfluid transition temperature show that when it is confined to flow in narrow cylindrical pores with nanometer radii, it tends to form concentric shells around a possible inner core. The latter potentially represents an experimental playground for exploring the implications of Luttinger liquid theory for one dimensional quantum fluids. We have performed large scale numerical simulations investigating the crossover from a bulk three dimensional superfluid to a one dimensional Luttinger liquid as the nanopore radius is reduced at low temperature. Measurements of the superfluid density employing both stiffness and angular momentum estimators provide new insights into confinement induced fluctuation effects in strongly interacting quantum fluids.

Kulchytskyy, Bohdan; Del Maestro, Adrian; Gervais, Guillaume

2013-03-01

60

Tomonaga–Luttinger liquid feature in sodium-doped quasi-one-dimensional trans-polyacetylene chain  

Microsoft Academic Search

We employ density functional theoretical calculation to establish Tomonaga–Luttinger liquid (TLL) behavior of sodium-doped quasi-one-dimensional trans-polyacetylene chain. A study of density of states near the Fermi energy demonstrates power-law dependence at doping concentrations 8.3%, 10.0% and 12.5%. The existence of power-law behavior in density of states is the signature of TLL behavior. Related power-law scaling factors are calculated from the

Sabyasachi Sen; Swapan Chakrabarti

2008-01-01

61

Conductance through a potential barrier embedded in a Luttinger liquid: Nonuniversal scaling at strong coupling  

NASA Astrophysics Data System (ADS)

We calculate the linear response conductance of electrons in a Luttinger liquid with arbitrary interaction g2 , and subject to a potential barrier of arbitrary strength, as a function of temperature. We map the Hamiltonian in the basis of scattering states into an effective low energy Hamiltonian in current algebra form. First the renormalization group (RG) equation for weak interaction is derived in the current operator language both using the operator product expansion and the equation of motion method. To access the strong coupling regime, two methods of deducing the RG equation from perturbation theory, based on the scaling hypothesis and on the Callan-Symanzik formulation, are discussed. The important role of scale-independent terms is emphasized. The latter depend on the regularization scheme used (length versus temperature cutoff). Analyzing the perturbation theory in the fermionic representation, the diagrams contributing to the renormalization group ? -function are identified. A universal part of the ? -function is given by a ladder series and summed to all orders in g2 . First nonuniversal corrections beyond the ladder series are discussed and are shown to differ from the exact solutions obtained within conformal field theory which use a different regularization scheme. The RG equation for the temperature-dependent conductance is solved analytically. Our result agrees with known limiting cases.

Aristov, D. N.; Wölfle, P.

2009-07-01

62

Luttinger liquids and composite fermions in nanostructures: what is the nature of the edge states in the fractional quantum Hall regime?  

Microsoft Academic Search

We study the Aharonov-Bohm conductance oscillations of a constriction with an antidot in the fractional quantum Hall regime using a recently proposed composite-fermion Fermi liquid theory, and also using Wen's chiral Luttinger liquid theory extended to include mesoscopic effects. The predictions of the composite-fermion Fermi liquid theory are very similar to standard Fermi liquid theory and are consistent with recent

Michael R Geller; Daniel Loss; George Kirczenow

1997-01-01

63

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

64

Thermalization of acoustic excitations in a strongly interacting one-dimensional quantum liquid.  

PubMed

We study inelastic decay of bosonic excitations in a Luttinger liquid. In a model with a linear excitation spectrum the decay rate diverges. We show that this difficulty is resolved when the interaction between constituent particles is strong, and the excitation spectrum is nonlinear. Although at low energies the nonlinearity is weak, it regularizes the divergence in the decay rate. We develop a theoretical description of the approach of the system to thermal equilibrium. The typical relaxation rate scales as the fifth power of temperature. PMID:23383812

Lin, Jie; Matveev, K A; Pustilnik, M

2013-01-02

65

Excitations of liquid  

Microsoft Academic Search

We report on neutron inelastic scattering measurements of the elementary excitations in liquid 4He in porous aerogel and Vycor glass. The measured dynamical structure factor is very similar to bulk 4He, with a similar temperature dependence. The small changes in the energy and width of the phonon-roton excitations and their temperature dependences reported earlier in aerogel are critically examined and

B. Fåk; O. Plantevin; H. R. Glyde

2000-01-01

66

Interacting bosons in one dimension and the applicability of Luttinger-liquid theory as revealed by path-integral quantum Monte Carlo calculations  

NASA Astrophysics Data System (ADS)

Harmonically trapped ultracold atoms and H4e in nanopores provide different experimental realizations of bosons in one dimension, motivating the search for a more complete theoretical understanding of their low-energy properties. Worm algorithm path-integral quantum Monte Carlo results for interacting bosons restricted to the one dimensional continuum are compared to the finite temperature and system size predictions of Luttinger-liquid theory. For large system sizes at low temperature, excellent agreement is obtained after including the leading irrelevant interactions in the Hamiltonian which are determined explicitly.

Del Maestro, Adrian; Affleck, Ian

2010-08-01

67

Transverse excitations in liquid Sn.  

PubMed

Transverse acoustic (TA) excitation modes were observed in inelastic x-ray scattering (IXS) spectra of liquid Sn. The excitation energies and widths of the TA modes are in good agreement with results of an ab initio molecular dynamics simulation. By comparing current correlation spectra between the experimental and theoretical results quantitatively, we have concluded that the TA modes can be detected experimentally through the quasi-TA branches in the longitudinal current correlation spectra. The lifetime and propagation length of the TA modes were determined to be ~0.7 ps and 0.8-1.0 nm, respectively, corresponding to the size of cages formed instantaneously in liquid Sn. PMID:23378432

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

2013-02-04

68

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

SciTech Connect

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

Law, K. T.; Feldman, D. E. [Department of Physics, Brown University, Providence, Rhode Island 02912 (United States)

2008-08-29

69

Elementary Excitations in Quantum Liquids.  

ERIC Educational Resources Information Center

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

Pines, David

1981-01-01

70

Transverse excitations in liquid metals  

NASA Astrophysics Data System (ADS)

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

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

2013-02-01

71

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

72

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

73

Equilibration of a one-dimensional quantum liquid  

NASA Astrophysics Data System (ADS)

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

Matveev, K. A.

2013-09-01

74

Acoustically excited air-assisted liquid sheets  

Microsoft Academic Search

The effect of acoustic excitation on the disintegration characteristics of air-assisted liquid sheets, which utilize water at ambient temperature, and for velocities up to 1.8 m\\/s, is investigated. The study using high-speed imaging techniques revealed that optimum frequency modulation of the perturbation generator has a pronounced influence on the associated surface waves and the subsequent breakup of the liquid sheet. The

V. Sivadas; E. C. Fernandes; M. V. Heitor

2003-01-01

75

Luttinger Theorem in One Dimensional Metals  

NASA Astrophysics Data System (ADS)

In one dimension (1D), the low energy physics is described by the Luttinger Liquid Theory (LLT). One of the characterizing features of the LLT is that the one-particle Green's function has a branch cut singularity instead of simple pole. Spin and charge are separated and propagate with different velocities. Experimentally, 1D physics have been observed in the quasi-one dimensional organic conductors. Recent proposals suggest that the essential physics of the high temperature superconducting cooper-oxides is a two dimensional version of the 1D LLT. In 1960 Luttinger proved a theorem, using a Fermi-like Green's function, stating that the volume of the Fermi surface is unchanged when the interactions are turned on and that the momentum distribution function has a discontinuity at the Fermi momentum of the noninteracting system. We show how this theorem is modified in a generic 1D model, namely the Tomonaga-Luttinger model and demonstrate the validity of the generalized version of the theorem. We discuss the implications for the high temperature superconductors.

Blagoev, Krastan B.; Bedell, Kevin S.

1997-03-01

76

Liquid storage tanks under vertical excitation  

SciTech Connect

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

Philippacopoulos, A.J.

1985-01-01

77

Micro-excitations in Coulomb liquids  

NASA Astrophysics Data System (ADS)

In a two-dimensional liquid melted from a triangular lattice, the accumulation of constructive perturbation from thermal noise and other external slow drive can cause stick slip type particle hopping over the caging barrier formed by the surrounding particles, which in turn distort the order lattice structure and generate topological defects. Through the strong mutual coupling, these nonlinear threshold-type micro-excitations of fast particles and topological defects usually occur in the form of avalanche type clusters involving a small number of sites. The dusty plasma liquid formed by suspending negatively charged micrometre sized particles in a low pressure discharge background turns out to be a good candidate to study the above spatio-temporal dynamical behaviours at the kinetic level through direct optical video microscopy. In this paper, we review our recent studies on this issue and compare the generic behaviours with other nonlinear coupled complex system excited by noise and other slow drives.

Lai, Ying-Ju; Woon, Wei-Yen; I, Lin

2004-12-01

78

Tomonaga-Luttinger physics in electronic quantum circuits.  

PubMed

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

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

2013-01-01

79

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

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

2013-01-01

80

Excitations of liquid 4He in porous media  

Microsoft Academic Search

We report on neutron inelastic scattering measurements of the elementary excitations in liquid 4He in porous aerogel and Vycor glass. The measured dynamical structure factor is very similar to bulk 4He, with a similar temperature dependence. The small changes in the energy and width of the phonon–roton excitations and their temperature dependences reported earlier in aerogel are critically examined and

B. Fåk; O. Plantevin; H. R. Glyde

2000-01-01

81

Quantum Liquid with Deconfined Fractional Excitations in Three Dimensions  

SciTech Connect

Excitations which carry 'fractional' quantum numbers are known to exist in one dimension in polyacetylene, and in two dimensions, in the fractional quantum Hall effect. Fractional excitations have also been invoked to explain the breakdown of the conventional theory of metals in a wide range of three-dimensional materials. However, the existence of fractional excitations in three dimensions remains highly controversial. In this Letter we report direct numerical evidence for the existence of an extended quantum liquid phase supporting fractional excitations in a concrete, three-dimensional microscopic model--the quantum dimer model on a diamond lattice. We demonstrate explicitly that the energy cost of separating fractional monomer excitations vanishes in this liquid phase, and that its energy spectrum matches that of the Coulomb phase in (3+1)-dimensional quantum electrodynamics.

Sikora, Olga [Max-Planck-Institut fuer Physik komplexer Systeme, 01187 Dresden (Germany); H. H. Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol BS8 1TL (United Kingdom); Pollmann, Frank [Department of Physics, University of California, Berkeley, California 94720 (United States); Shannon, Nic [H. H. Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol BS8 1TL (United Kingdom); Penc, Karlo [Research Institute for Solid State Physics and Optics, H-1525 Budapest, P.O.B. 49 (Hungary); Fulde, Peter [Max-Planck-Institut fuer Physik komplexer Systeme, 01187 Dresden (Germany); Asia Pacific Center for Theoretical Physics, Pohang (Korea, Republic of)

2009-12-11

82

Effective interactions and elementary excitations in quantum liquids  

SciTech Connect

The effective interactions which provide a wavevector and frequency dependent restoring force for collective modes in quantum liquids are derived for the helium liquids by means of physical arguments and sum rule and continuity considerations. A simple model is used to take into account mode-mode coupling between collective and multiparticle excitations, and the results for the zero-temperature liquid /sup 4/He phonon-maxon-roton spectrum are shown to compare favorably with experiment and with microscopic calculation. The role played by spin-dependent backflow in liquid /sup 3/He is analyzed, and a physical interpretation of its variation with density and spin-polarization is presented. A progress report is given on recent work on effective interactions and elementary excitations in nuclear matter, with particular attention to features encountered in the latter system which have no counterparts in the helium liquids.

Pines, D.

1986-01-01

83

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

SciTech Connect

The authors use transient absorption spectroscopy to monitor the ionization and dissociation products following two-photon excitation of pure liquid water. The primary decay mechanism changes from dissociation at an excitation energy of 8.3 eV to ionization at 12.4 eV. The two channels occur with similar yield for an excitation energy of 9.3 eV. For the lowest excitation energy, the transient absorption at 267 nm probes the geminate recombination kinetics of the H and OH fragments, providing a window 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 0.7{+-}0.2 nm. Our observation suggests that the hydrogen bonding environment does not prevent direct dissociation of an O-H bond in the excited state. We discuss the implications of our measurement for the excited state dynamics of liquid water and explore the role of those dynamics in the ionization mechanism at low excitation energies.

Elles, Christopher G.; Shkrob, Ilya A.; Crowell, Robert A.; Bradforth, Stephen E. [Chemistry Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Department of Chemistry, University of Southern California, Los Angeles, California 90089 (United States)

2007-04-28

84

Dynamics of Excitations in a One-Dimensional Bose Liquid  

SciTech Connect

We show that the dynamic structure factor of a one-dimensional Bose liquid has a power-law singularity defining the main mode of collective excitations. Using the Lieb-Liniger model, we evaluate the corresponding exponent as a function of the wave vector and the interaction strength.

Khodas, M.; Glazman, L. I. [William I. Fine Theoretical Physics Institute and School of Physics and Astronomy, University of Minnesota, Minneapolis, Minnesota 55455 (United States); Pustilnik, M. [School of Physics, Georgia Institute of Technology, Atlanta, Georgia 30332 (United States); Kamenev, A. [School of Physics and Astronomy, University of Minnesota, Minneapolis, Minnesota 55455 (United States)

2007-09-14

85

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

86

A quantum liquid with deconfined fractional excitations in three dimensions  

NASA Astrophysics Data System (ADS)

Excitations which carry ``fractional'' quantum numbers are known to exist in one dimension in polyacetylene, and in two dimensions, in the fractional quantum Hall effect. Fractional excitations have also been invoked to explain the breakdown of the conventional theory of metals in a wide range of three-dimensional materials. However the existence of fractional excitations in three dimensions remains highly controversial. Here we report direct numerical evidence for the existence of an extended quantum liquid phase supporting fractional excitations in a concrete, three-dimensional microscopic model --- the quantum dimer model on a diamond lattice [1]. We demonstrate explicitly that the energy cost of separating fractional monomer excitations vanishes in this liquid phase, and that its energy spectrum matches that of the Coulomb phase in (3+1) dimensional quantum electrodynamics [2,3]. [4pt] [1] O. Sikora et al. arXiv:0901.1057v3 --- to appear in Phys. Rev. Lett. [0pt] [2] R. Moessner and S.L. Sondhi, Phys. Rev. B 68, 184512 (2003).[0pt] [3] D.L. Bergman et al. Phys. Rev. B 73, 134402 (2006).

Shannon, Nic; Sikora, Olga; Pollmann, Frank; Penc, Karlo; Fulde, Peter

2010-03-01

87

Energy Spectrum of the Excitations in Liquid Helium  

Microsoft Academic Search

A wave function previously used to represent an excitation (phonon or roton) in liquid helium, inserted into a variational principle for the energy, gave an energy-momentum curve having the qualitative shape suggested by Landau; but the value computed for the minimum energy Delta of a roton was 19.1°K, while thermodynamic data require Delta=9.6°K. A new wave function is proposed here.

Michael Cohen

1956-01-01

88

Collective excitations of holographic quantum liquids in a magnetic field  

NASA Astrophysics Data System (ADS)

We use holography to study {N} = 4 supersymmetric SU( N c) Yang-Mills theory in the large- N c and large-coupling limits coupled to a number N f ? N c of ( n + 1)-dimensional massless supersymmetric hypermultiplets in the fundamental representation of SU(Nc), with n = 2, 3. We introduce a temperature T, a baryon number chemical potential ?, and a baryon number magnetic field B, and work in a regime with ? ? T, ?{B} . We study the collective excitations of these holographic quantum liquids by computing the poles in the retarded Green's function of the baryon number charge density operator and the associated peaks in the spectral function. We focus on the evolution of the collective excitations as we increase the frequency relative to T , i.e. the hydrodynamic/collisionless crossover. We find that for all B, at low frequencies the tallest peak in the spectral function is associated with hydrodynamic charge diffusion. At high frequencies the tallest peak is associated with a sound mode similar to the zero sound mode in the collisionless regime of a Landau Fermi liquid. The sound mode has a gap proportional to B, and as a result for intermediate frequencies and for B sufficiently large compared to T the spectral weight is strongly suppressed. We find that the hydrodynamic/collisionless crossover occurs at a frequency that is approximately B-independent.

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

2012-11-01

89

Photo-excitation dynamics of malachite green in ionic liquids studied by the transient grating method  

NASA Astrophysics Data System (ADS)

Photo-excitation dynamics of malachite green in ionic liquids has been studied by the transient grating method. Anomalies of the S1 lifetime and vibrational energy relaxation are found together with the structural relaxation of ionic liquid.

Fukuda, Masanori; Kajimoto, Okitsugu; Terazima, Masahide; Kimura, Yoshifumi

90

Frustration dependence of elementary excitation in a quantum spin liquid  

NASA Astrophysics Data System (ADS)

A quantum spin liquid state (QSL) with a magnetic gapless excitation has been found in the organic Mott insulator EtMe3Sb[Pd(dmit)2]2 with nearly identical 2D triangular lattices of S = 1/2 [1]. To examine the nature of the QSL, it is essential to determine the phase diagram, especially how the gapless QSL evolves when the degree of frustration is changed. Although the gapless QSL is shown to be robust against deuteration of the cation EtMe3Sb [1], the difference of frustration caused by the deuteration is not clear. We study the frustration dependence of the elementary excitation in the mixed-cation materials (Me4Sb)1-x(EtMe3Sb)x[Pd(dmit)2]2 in which the degree of frustration is directly reduced by mixing the smaller cation. Magnetic torque measurements showed that spin susceptibilities of the mixed cation (x = 0.32 and 0.35) were temperature independent down to 30 mK and were almost the same with that of x = 1, indicating that the QSL exists as a quantum critical phase, rather than a point, when the frustration is varied. We will also present magnetic torque and thermal transport measurements of mixed-cation materials with different x.[4pt] [1] D. Watanabe et al., Nat. commun. 3, 1090 (2012).

Yamashita, M.; Ueda, K.; Cui, H.; Kato, R.; Yamamoto, H. M.; Fukunaga, T.; Terashima, T.; Uji, S.

2013-03-01

91

Novel edge excitations of two-dimensional electron liquid in a magnetic field  

Microsoft Academic Search

We investiggate the low-energy spectrum of excitations of a compressible electron liquid in a strong magnetic field. These excitations are localized at the periphery of the system. The analysis of a realistic model of a smooth edge yields new branches of acoustic excitation spectrum in addition to the well known edge magnetoplasmon mode. The velocities are found and the observability

I. L. Aleiner; L. I. Glazman

1994-01-01

92

Acoustic excitations of a confined two-dimensional electron liquid in a magnetic field  

Microsoft Academic Search

We study the low-frequency excitations of a compressible electron liquid confined to a strip and subjected to a magnetic field. Using the classical equations of motion, we show the existence of gapless excitations additional to the conventional one-dimensional plasmon. These excitations are shown to have linear spectra. In contrast to the plasmon mode, the velocities of these modes increase with

I. L. Aleiner; Dongxiao Yue; L. I. Glazman

1995-01-01

93

On the Kohn-Luttinger conundrum  

NASA Astrophysics Data System (ADS)

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; He, Xiao

2013-05-01

94

Edge spin excitations and reconstructions of integer quantum Hall liquids  

NASA Astrophysics Data System (ADS)

We study the effect of electron-electron interaction on the charge and spin structures at the edge of integer quantum Hall liquids, under three different kinds of confining potentials. Our exact diagonalization calculation for small systems indicates that the low-energy excitations of the ?=1 ferromagnetic state are bosonic edge spin waves. Instabilities of the ferromagnetic state with altering confinement strength result from the softening of these edge spin waves and formation of edge spin textures. In the ??2 regime, exact diagonalization on edge electron systems indicates that compact Hartree-Fock states with different total spin always become ground states in some regions of parameter space, and the ground states appearing between two compact states are their edge spin waves. The initial ?=2 instability is toward the compact state with total spin 1. Larger systems are studied using a microscopic trial wave function, and some quantitative predictions on the edge instabilities for a certain type of confining potential are reached in the thermodynamic limit.

Zhang, Yuhui; Yang, Kun

2013-03-01

95

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

96

Femtosecond solvation dynamics in a neat ionic liquid and ionic liquid microemulsion: excitation wavelength dependence.  

PubMed

Solvation dynamics in a neat ionic liquid, 1-pentyl-3-methyl-imidazolium tetra-flouroborate ([pmim][BF4]) and its microemulsion in Triton X-100 (TX-100)/benzene is studied using femtosecond up-conversion. In both the neat ionic liquid and the microemulsion, the solvation dynamics is found to depend on excitation wavelength (lambda(ex)). The lambda(ex) dependence is attributed to structural heterogeneity in neat ionic liquid (IL) and in IL microemulsion. In neat IL, the heterogeneity arises from clustering of the pentyl groups which are surrounded by a network of cation and anions. Such a nanostructural organization is predicted in many recent simulations and observed recently in an X-ray diffraction study. In an IL microemulsion, the surfactant (TX-100) molecules aggregate in form of a nonpolar peripheral shell around the polar pool of IL. The micro-environment in such an assembly varies drastically over a short distance. The dynamic solvent shift (and average solvation time) in neat IL as well as in IL microemulsions decreases markedly as lambda(ex) increases from 375 to 435 nm. In a [pmim][BF4]/water/TX-100/benzene quaternary microemulsion, the solvation dynamics is slower than that in a microemulsion without water. This is ascribed to the smaller size of the water containing microemulsion. The anisotropy decay in an IL microemulsion is found to be faster than that in neat IL. PMID:17944511

Adhikari, Aniruddha; Sahu, Kalyanasis; Dey, Shantanu; Ghosh, Subhadip; Mandal, Ujjwal; Bhattacharyya, Kankan

2007-10-18

97

Conformal field theory in the Tomonaga Luttinger model with the 1/r? long-range interaction  

NASA Astrophysics Data System (ADS)

We attempt to construct U(1) conformal field theory (CFT) in the Tomonaga-Luttinger (TL) liquid with the 1/r? long-range interaction (LRI). Treating the long-range forward scattering as a perturbation and applying CFT to it, we derive finite size scalings which depend on the power of the LRI. The obtained finite size scalings give nontrivial behaviours when ? is odd and is close to 2. We find consistency between the analytical arguments and numerical results in the finite size scaling of energy.

Inoue, Hitoshi; Nomura, Kiyohide

2006-03-01

98

Nature of excited helium atoms in liquid helium: a theoretical model  

Microsoft Academic Search

A model is developed in which excited helium atoms in liquid helium may exist in stable cavities of diameter 10 A and larger. A repulsive effective interaction between the excited atom and the remaining atoms in the ground state is responsible for cavity formation. The equilibrium shape of the cavity is determined by minimizing the total energy, which is the

A. P. Hickman; W. Steets

1975-01-01

99

Parametrically excited sectorial oscillation of liquid drops floating in ultrasound.  

PubMed

We report experiments in which the nonaxisymmetric sectorial oscillations of water drops have been excited using acoustic levitation and an active modulation method. The observed stable sectorial oscillations are up to the seventh mode. These oscillations are excited by parametric resonance. The oblate initial shape of the water drops is essential to this kind of excitations. The oscillation frequency increases with mode number but decreases with equatorial radius for each mode number. The data can be well described by a modified Rayleigh equation, without the use of additional parameters. PMID:20481825

Shen, C L; Xie, W J; Wei, B

2010-04-09

100

Parametrically excited sectorial oscillation of liquid drops floating in ultrasound  

NASA Astrophysics Data System (ADS)

We report experiments in which the nonaxisymmetric sectorial oscillations of water drops have been excited using acoustic levitation and an active modulation method. The observed stable sectorial oscillations are up to the seventh mode. These oscillations are excited by parametric resonance. The oblate initial shape of the water drops is essential to this kind of excitations. The oscillation frequency increases with mode number but decreases with equatorial radius for each mode number. The data can be well described by a modified Rayleigh equation, without the use of additional parameters.

Shen, C. L.; Xie, W. J.; Wei, B.

2010-04-01

101

Excitation of electric signals during laser irradiation of liquid surface  

Microsoft Academic Search

Mechanisms for excitation of electric signals (ESs) during laser irradiation of an open water surface are analyzed. An explanation\\u000a is proposed for the time dependence of the ESs, and the maximum possible ES amplitudes are evaluated.

A. M. Boichenko

2009-01-01

102

Sloshing of liquid in rigid cylindrical container with multiple rigid annular baffles: Lateral excitations  

NASA Astrophysics Data System (ADS)

Sloshing response of liquid in a rigid cylindrical container with multiple annual rigid baffles subjected to lateral excitations has been studied. Firstly, the liquid domain is divided into several simple sub-domains so that the liquid velocity potential in each liquid sub-domain has continuous boundary conditions of class C1. Based on the superposition principle, the analytical solutions of the liquid velocity potential corresponding to each liquid sub-domain are obtained by means of the method of separation of variables. The total velocity potential function under lateral excitation is taken as the sum of the container potential function and the liquid perturbed potential function. The orthogonality among the modes of liquid velocity potential is demonstrated. The dynamic response equation of liquid is established by substituting the liquid potential functions into the free surface wave equation. Finally, the surface wave height, hydrodynamic pressure distribution, resultant hydrodynamic force and moment for a container subjected to harmonic and seismic lateral excitations are discussed in detail.

Wang, J. D.; Lo, S. H.; Zhou, D.

2013-10-01

103

Response of a solidly rotating amphora-type liquid column to axial excitation  

NASA Astrophysics Data System (ADS)

The response of a solidly rotating finite liquid column, which under the action of an axial gravity assumes an amphora-type equilibrium position, has been determined to axial excitation. The column consists of incompressible and frictionless liquid. The response of the free surface elevation has been obtained for the elliptic ( ? > 2? 0) frequency range.

Bauer, Helmut F.; Eidel, Werner

104

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

Microsoft Academic Search

A variety of recent experiments probing the low-temperature transport properties of quantum Hall systems have suggested an interpretation in terms of liquid crystalline mesophases dubbed quantum Hall liquid crystals. The single mode approximation (SMA) has been a useful tool for the determination of the excitation spectra of various systems such as phonons in He4 and in the fractional quantum Hall

Cintia M. Lapilli; Carlos Wexler

2006-01-01

105

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

Microsoft Academic Search

A variety of recent experiments probing the low-temperature transport properties of quantum Hall systems have suggested an interpretation in terms of liquid crystalline mesophases dubbed quantum Hall liquid crystals. The single mode approximation (SMA) has been a useful tool for the determination of the excitation spectra of various systems such as phonons in ⁴He and in the fractional quantum Hall

Cintia M. Lapilli; Carlos Wexler

2006-01-01

106

Coupling dynamic analysis of a liquid-filled spherical container subject to arbitrary excitation  

NASA Astrophysics Data System (ADS)

Using spherical coordinates, the coupling nonlinear dynamic system of a liquid-filled spherical tank, which can be excited discretionarily, is deduced by the H-O variational principle, and the viscous damping is introduced via the liquid dissipation function. The kinetic equations of the coupling system are deduced by the relationship between the velocity of liquid particles and the disturbed liquid surface equation. Normal differential equations are obtained through the Galerkin method. An equivalent mechanical model is developed for liquid sloshing in a spherical tank subject to arbitrary excitation. The fixed and slosh masses, as well as the spring and damping constants, are determined in such a way as to satisfy the principle of equivalence. Numerical simulations illustrate the theoretical results in this paper as well.

Lü, Jing; Wang, Shimin; Wang, Tianshu

2012-08-01

107

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

108

Fractionalized excitations in the spin-liquid state of a kagome-lattice antiferromagnet.  

PubMed

The experimental realization of quantum spin liquids is a long-sought goal in physics, as they represent new states of matter. Quantum spin liquids cannot be described by the broken symmetries associated with conventional ground states. In fact, the interacting magnetic moments in these systems do not order, but are highly entangled with one another over long ranges. Spin liquids have a prominent role in theories describing high-transition-temperature superconductors, and the topological properties of these states may have applications in quantum information. A key feature of spin liquids is that they support exotic spin excitations carrying fractional quantum numbers. However, detailed measurements of these 'fractionalized excitations' have been lacking. Here we report neutron scattering measurements on single-crystal samples of the spin-1/2 kagome-lattice antiferromagnet ZnCu(3)(OD)(6)Cl(2) (also called herbertsmithite), which provide striking evidence for this characteristic feature of spin liquids. At low temperatures, we find that the spin excitations form a continuum, in contrast to the conventional spin waves expected in ordered antiferromagnets. The observation of such a continuum is noteworthy because, so far, this signature of fractional spin excitations has been observed only in one-dimensional systems. The results also serve as a hallmark of the quantum spin-liquid state in herbertsmithite. PMID:23257883

Han, Tian-Heng; Helton, Joel S; Chu, Shaoyan; Nocera, Daniel G; Rodriguez-Rivera, Jose A; Broholm, Collin; Lee, Young S

2012-12-20

109

Effective interactions, elementary excitations, and transport in the helium liquids  

SciTech Connect

Polarization potentials, the self-consistent fields which describe the primary consequences of the strong atom-atom interaction in the helium liquids, are developed for liquid /sup 4/He and /sup 3/He. Emphasis is placed on the common physical origin of the effective interactions in all helium liquids, and the hierarchy of physical effects (very short-range atomic correlations, zero point motion, and the Pauli principle) which determine their strength is reviewed. An overview is then given of the application of polarization potential theory to experiment, including the phonon-maxon-roton spectra of /sup 4/He and /sup 3/He-/sup 4/He mixtures, the phonon-maxon spectrum of normal and spin-polarized /sup 3/He, and the transport properties of superfluid /sup 4/He and of normal and spin-polarized /sup 3/He.

Pines, D.

1986-01-01

110

Excitations and Bose-Einstein condensation in liquid 4He  

NASA Astrophysics Data System (ADS)

We present a model of the dynamic structure factor S(Q,?) of He4 that reproduces the basic features of the temperature dependence of S(Q,?) as observed in inelastic-neutron scattering measurements. Wave vectors Q beyond the roton ( Q>2.0Å-1 ) are considered. The model is able to reproduce the decrease in the intensity of the single excitation (phonon-roton) peak in S(Q,?) with an increase of temperature (T) in the range 0.6?T?2.1K . All vertices and interactions are assumed temperature independent, and only the condensate fraction n0(T) changes with T . Also, it reproduces a second peak observed at higher energy ( ? ) which represents the single excitation intensity lying in the two excitation band. The model is based on the formulation of S(Q,?) of Gavoret and Nozières. In this formulation, the dynamic susceptibility, ? , is separated into a singular part involving the condensate and a regular part involving states above the condensate ?=?S+?R' . The weight of the phonon-roton peak in ?S is proportional to n0(T) and the phonon-roton peak disappears completely from ? in the normal phase where n0(T)=0 . Using sum rule arguments, the condensate fraction can be estimated from the data giving values in good agreement with accurate measurements at SVP and with Monte Carlo calculations.

Sakhel, A. R.; Glyde, H. R.

2004-10-01

111

Elementary excitations in quantum Bose fluids: Application to liquid 4He  

Microsoft Academic Search

The optimizing Euler equations for the dynamic linear-response function are derived starting from the Jastrow ansatz for the wave function and including also the backflow effect. The elementary excitations in liquid 4He are calculated consistently using the hypernetted-chain approximation for the uniform system as well as for weakly disturbed static and dynamic systems. The resulting excitation-energy spectrum is found to

M. Saarela

1986-01-01

112

Absence of Luttinger's Theorem due to Zeros in the Single-Particle Green Function  

NASA Astrophysics Data System (ADS)

We show exactly with an SU(N) interacting model that even if the ambiguity associated with the placement of the chemical potential, ?, for a T=0 gapped system is removed by using the unique value ?(T?0), Luttinger’s sum rule is violated even if the ground-state degeneracy is lifted by an infinitesimal hopping. The failure stems from the nonexistence of the Luttinger-Ward functional for a system in which the self-energy diverges. Since it is the existence of the Luttinger-Ward functional that is the basis for Luttinger’s theorem which relates the charge density to sign changes of the single-particle Green function, no such theorem exists. Experimental data on the cuprates are presented which show a systematic deviation from the Luttinger count, implying a breakdown of the electron quasiparticle picture in strongly correlated electron matter.

Dave, Kiaran B.; Phillips, Philip W.; Kane, Charles L.

2013-03-01

113

Neutron scattering study of elementary excitations in liquid helium-3  

Microsoft Academic Search

The neutron inelastic scattering function of liquid helium-3 at 0.015 K has been measured for wave vectors in the range 0.8 A⁻¹< or =q< or =2.2 A⁻¹. For q<1.4 A⁻¹, the scattering function contains two peaks. The peak at lower energy is due to spin-fluctuation scattering in the particle-hole region while the peak at higher energy is identified to be

K. Skold; C. A. Pelizzari; R. Kleb; G. E. Ostrowski

1976-01-01

114

Triphenylene Columnar Liquid Crystals: Excited States and Energy Transfer  

Microsoft Academic Search

The present paper deals with the photophysical properties of columnar liquid crystals formed by hexakis- (alky1oxy)triphenylenes. Absorption and fluorescence spectra of solutions are analyzed on the basis of quantum chemical calculations performed by the CS-INDO-CI (conformations spectra-intermediate neglect of differential overlap-configuration interaction) methd. the absorption maximum is due to the SO - Sq transition while fluorescence originates from the weak

Dimitra Markovitsi; Arnaud Germain; Philippe Millie; Pierre LCcuyert; Lazaros K. Gallos; Panos Argyrakis; Holger Bengss; Helmut Ringsdorf

1995-01-01

115

Pressure dependence of elementary excitations in normal liquid helium-3  

Microsoft Academic Search

The neutron scattering function for liquid 3He at 120 mK and pressures of 9, 0.5, 1, and 2 MPa has been determined for wave vectors in the range 3 nm-1

R. Scherm; K. Guckelsberger; B. Fak; K. Sköld; A. J. Dianoux; H. Godfrin; W. G. Stirling

1987-01-01

116

Quench dynamics of the Tomonaga-Luttinger model with momentum-dependent interaction  

NASA Astrophysics Data System (ADS)

We study the relaxation dynamics of the one-dimensional Tomonaga-Luttinger model after an interaction quench, paying particular attention to the momentum dependence of the two-particle interaction. Several potentials of different analytical forms are investigated that all lead to universal Luttinger liquid (LL) physics in equilibrium. The steady-state fermionic momentum distribution shows universal behavior in the sense of the LL phenomenology. For generic regular potentials, the large time decay of the momentum distribution function toward the steady-state value is characterized by a power law with a universal exponent that depends only on the potential at zero momentum transfer. The commonly employed ad hoc procedure fails to give this exponent. In addition to quenches from zero to positive interactions, we also consider the abrupt changes in the interaction between two arbitrary values. Additionally, we discuss the appearance of a factor of two between the steady-state momentum distribution function and that obtained in equilibrium at equal two-particle interaction.

Rentrop, J.; Schuricht, D.; Meden, V.

2012-07-01

117

Two-Photon Excitation of Dye-Doped Liquid Crystal by a CW-Laser Irradiation  

Microsoft Academic Search

We report on excitation of photoluminescence via two-photon absorption (2PA) in dye-doped liquid crystal droplets using tightly focused cw-laser illumination at 1064 nm wavelength. The photoluminescence of the 2PA dye C40H54N2O2 (MBAPB) dispersed inside the 7CB liquid crystal host increases as square of the laser tweezers' irradiance. The 2PA cross-section of MBAPB was measured by femtosecond Z-scan method. The polarization and

Naoki Murazawa; Saulius Juodkazis; Hiroaki Misawa; Kenji Kamada

2008-01-01

118

Flashlamp-Excited Organic Liquid Laser in the Range from 342 to 889 nm  

Microsoft Academic Search

Using a perfectly coaxial flashlamp-excited organic liquid laser system, the stimulated emission from 36 compounds, which include 12 new lasing compounds, in the range from 342 to 889 nm is reported. The flashlamp has a rise time of 80 nsec, and the lasing threshold of this system is very low. A list of 36 laser compounds and central wavelength and

Mitsuo Maeda; Yashushi Miyazoe

1972-01-01

119

Highly mobile gapless excitations in a two-dimensional candidate quantum spin liquid.  

PubMed

The nature of quantum spin liquids, a novel state of matter where strong quantum fluctuations destroy the long-range magnetic order even at zero temperature, is a long-standing issue in physics. We measured the low-temperature thermal conductivity of the recently discovered quantum spin liquid candidate, the organic insulator EtMe3Sb[Pd(dmit)2]2. A sizable linear temperature dependence term is clearly resolved in the zero-temperature limit, indicating the presence of gapless excitations with an extremely long mean free path, analogous to excitations near the Fermi surface in pure metals. Its magnetic field dependence suggests a concomitant appearance of spin-gap-like excitations at low temperatures. These findings expose a highly unusual dichotomy that characterizes the low-energy physics of this quantum system. PMID:20522768

Yamashita, Minoru; Nakata, Norihito; Senshu, Yoshinori; Nagata, Masaki; Yamamoto, Hiroshi M; Kato, Reizo; Shibauchi, Takasada; Matsuda, Yuji

2010-06-01

120

Ab initio study on an excited-state intramolecular proton-transfer reaction in ionic liquid.  

PubMed

An excited-state intramolecular proton transfer (ESIPT) reaction of 4'-N,N-dimethylamino-3-hydroxyflavone in room temperature ionic liquid is theoretically investigated using RISM-SCF-SEDD, which is a hybrid method of molecular liquid theory and ab initio molecular orbital theory. The photo-excitation and proton-transfer processes are computed by considering the solvent fluctuation. The calculated absorption and emission energy are in good agreement with the experiments. The changes in the dipole moment indicate that the drastic solvation relaxation is accompanied by the excitation and an ESIPT process, which is consistent with the remarkable dynamic Stokes shift observed in the experiments. We calculated the nonequilibrium free-energy contour as a function of the proton coordinate and the solvation coordinate. We conclude that although immediately after the excitation the barrier height of the ESIPT process is relatively small, the barrier becomes larger as the solvation relaxation to the excited normal state proceeds. The solvation relaxation process is also investigated on the basis of microscopic solvation structure obtained by RISM calculations. PMID:23697807

Hayaki, Seigo; Kimura, Yoshifumi; Sato, Hirofumi

2013-05-22

121

Avalanche Excitations of Fast Particles in Quasi-2D Cold Dusty-Plasma Liquids  

NASA Astrophysics Data System (ADS)

We study the spatiotemporal cooperative microexcitations in quasi-2D cold dusty-plasma liquids from the view of the coupled subexcitable nonlinear dynamical system. Under the interplay of thermal noise and mutual coupling, cooperative fast-particle clusters are excited in the xyt space. The fast hopping plays a major role in the superdiffusion with non-Gaussian velocity distribution and causes the loss of bond-orientation memory. The size distribution of the excited clusters in the xyt space follows a similar avalanche-type power-law relation as in other subexcitable systems.

Lai, Ying-Ju; I, Lin

2002-09-01

122

Enhancement of the shot noise of a quantum dot-Luttinger lead system  

NASA Astrophysics Data System (ADS)

We investigate the joint effects of the intralead electron interaction and Coulombic dot-lead interaction on the shot noise of a quantum dot coupled to Luttinger liquid leads. A formula of the shot noise is derived by applying the nonequilibrium Green function technique. The shot noise is enhanced by the dot-lead interaction. For a weak or moderately strong interaction the differential shot noise demonstrates resonant-like behavior as a function of bias and gate voltages. In the limit of strong interaction resonant behavior disappears and the differential shot noise and Fano factor scale as a power law in bias voltage. Under some parameters, the differential shot noise may become negative around resonant peaks, and the physical reason is analyzed.

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

2013-10-01

123

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

NASA Astrophysics Data System (ADS)

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

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

2008-10-01

124

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

125

Phonon-Roton Excitations and Quantum Phase Transitions in Liquid 4HE in Nanoporous Media  

Microsoft Academic Search

We present measurements of the elementary phonon-roton and other excitations of liquid 4He confined in nanoporous media using inelastic neutron scattering methods. The aim is to compare phonon-roton (P-R) and superfluid density measurements and to explore the interdependence of Bose-Einstein Condensation (BEC), P-R modes and superfluidity in helium at nanoscales and in disorder. Specifically a goal is to determine the

Henry R. Glyde; Jonathan V. Pearce; Jacques Bossy; Helmut Schober

2008-01-01

126

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

SciTech Connect

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

Lapilli, Cintia M.; Wexler, Carlos [Department of Physics and Astronomy, University of Missouri-Columbia, Columbia, Missouri 65211 (United States)

2006-02-15

127

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.

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

2013-01-01

128

Theory of Fermion Liquids  

Microsoft Academic Search

I develop a general theory of fermion liquids in spatial dimensions greater than one. Bosonization is the principal method. I first review the case of one spatial dimension where bosonization is most neat and exact and show that a non-Fermi Luttinger liquid fixed point is obtained even with short-range interactions. Generalized bosonization is constructed in higher dimensions and the method

Hyok-Jon Kwon; A. Houghton; J. B. Marston

1995-01-01

129

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.

Morrison, L E; Weber, G

1987-01-01

130

Semiclassical Time Evolution of the Holes from Luttinger Hamiltonian  

SciTech Connect

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

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

2010-02-15

131

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

132

Neutron investigation of the ion dynamics in liquid mercury: evidence for collective excitations.  

PubMed

The ion dynamics of liquid mercury was investigated by inelastic neutron scattering. By exploiting an optimized high-resolution ( approximately 1 meV) experimental configuration, the dynamic response function was accurately measured. Collective excitations extending up to 0.6 A(-1) were observed with an associated velocity of 2100+/-80 m/s. This value is notably greater than the sound velocity, but it is provided by a simple Bohm-Staver calculation. The latter finding emphasizes those electron-related features in the ion dynamics, which are common to systems as different as polyvalent and alkali metals. PMID:11736350

Bove, L E; Sacchetti, F; Petrillo, C; Dorner, B; Formisano, F; Barocchi, F

2001-11-02

133

Nonlinear transports and microvortex excitations in sheared quasi-two-dimensional dust Coulomb liquids  

NASA Astrophysics Data System (ADS)

The microscopic spatiotemporal response of a quasi-two-dimensional dust Coulomb liquid to the shear induced by a cw laser is investigated through optical microscopy. The dust Coulomb liquid consists of many micrometer sized dust particles charged and suspended in a low pressure rf discharge background. Assisted by thermal fluctuations, the laser forcing enhances the cascaded generation of irregular vortices through reducing caging barriers for collective hopping. The vortex mixing leads to the mean velocity field with a simple structure that has a strong shear along the edge of the narrow laser beam. It also promotes the anomalous transverse diffusion with decaying strength from the line source. The viscosity and diffusion coefficient both show nonlinear dependence on the laser power under the interplay among the above nonlinear excitation and relaxation processes.

Juan, Wen-Tau; Chen, Ming-Heng; I, Lin

2001-07-01

134

Phonon-Roton Excitations and Quantum Phase Transitions in Liquid 4HE in Nanoporous Media  

NASA Astrophysics Data System (ADS)

We present measurements of the elementary phonon-roton and other excitations of liquid 4He confined in nanoporous media using inelastic neutron scattering methods. The aim is to compare phonon-roton (P-R) and superfluid density measurements and to explore the interdependence of Bose-Einstein Condensation (BEC), P-R modes and superfluidity in helium at nanoscales and in disorder. Specifically a goal is to determine the region of temperature and pressure in which well defined phonon-roton modes exist and compare this with the superfluid phase diagram. In porous media the liquid phase is extended up to 35-40 bars. A second goal is to investigate helium at higher pressures. At low temperature and at saturated vapor pressure (SVP) (p ? 0) liquid 4He supports well defined P-R modes in all porous media investigated to date (aerogel, xerogel, Vycor, MCM-41 and gelsil of several pore diameters). As temperature is increased at SVP, the P-R modes broaden but well defined modes exist above Tc in the normal phase, up to T?. The superfluid to normal transition temperature, Tc, in porous media always lies below the corresponding temperature, T?, in bulk helium. In liquid 4He in 25 Å and 34 Å mean pore diameter gelsil under pressure and at low temperature, we observe loss of all well defined P-R modes at p = 36.3 - 36.8 bars. Yamamoto et al. have observed a possible Quantum Phase Transition (QPT) (T?0 K) from the superfluid to normal liquid at p = 34 bars in superfluid density measurements. The existence of P-R modes under pressure up to 36.3 bars and their subsequent loss supports the finding of a QPT. We discuss the implications of these results for the basic concepts of BEC and superfluidity in helium at nanoscales and in disorder.

Glyde, Henry R.; Pearce, Jonathan V.; Bossy, Jacques; Schober, Helmut

2008-06-01

135

Effect of applied ac electric field on surface plasmon excitations at metal/liquid-crystal interface  

NASA Astrophysics Data System (ADS)

It is well known that surface plasmon polaritons (SPPs) can be excited by p-polarized laser beam incident upon high-index prism/metal/dielectric medium used in Kretschmann configuration. The SPPs' onset, evidenced by a loss in the intensity of totally reflected light at a certain angle greater than the critical angle for total reflection, is sensitive to the dielectric properties of the medium. In the case when the dielectric medium is liquid crystal (LC), its dielectric properties can be modified by applied electric fields. We have carried out a set of experiments on high-index prism/Au/LC used in the Kretschmann configuration. Specifically, we have measured a set of attenuated total reflection (ATR) data as functions of incident angle for p-polarized 632 nm laser beam and ac electric fields for liquid crystals. We present data on the effects of the applied ac electric fields on the nature of the reflectivity vs angle curves and discuss the relevance of our observations to the electric-field-induced changes in the dielectric properties of the liquid crystal.

Tiwari, Kunal; Sharma, Suresh

2013-03-01

136

Excitation lines and the breakdown of Stokes-Einstein relations in supercooled liquids  

NASA Astrophysics Data System (ADS)

By applying the concept of dynamical facilitation and analyzing the excitation lines that result from this facilitation, we investigate the origin of decoupling of transport coefficients in supercooled liquids. We illustrate our approach with two classes of models. One depicts diffusion in a strong glass former, and the other in a fragile glass former. At low temperatures, both models exhibit violation of the Stokes-Einstein relation, D˜ ?-1 , where D is the self-diffusion constant and ? is the structural relaxation time. In the strong case, the violation is sensitive to dimensionality d , going as D˜ ?-2/3 for d=1 and as D˜ ?-0.95 for d=3 . In the fragile case, however, we argue that dimensionality dependence is weak, and show that for d=1 , D˜ ?-0.73 . This scaling for the fragile case compares favorably with the results of a recent experimental study for a three-dimensional fragile glass former.

Jung, Younjoon; Garrahan, Juan P.; Chandler, David

2004-06-01

137

Excitation lines and the breakdown of Stokes-Einstein relations in supercooled liquids  

NASA Astrophysics Data System (ADS)

By applying the concept of dynamical facilitation and analyzing the excitation lines that result from this facilitation, we investigate the origin of decoupling of transport coefficients in supercooled liquids. We illustrate our approach with two classes of models. One depicts diffusion in a strong glass former, and the other in a fragile glass former. At low temperatures, both models exhibit violation of the Stokes-Einstein relation, D ˜?-1, where D is the self diffusion constant and ? is the structural relaxation time. In the strong case, the violation is sensitive to dimensionality d, going as D ˜?-2/3 for d=1, and as D ˜ ?-0.95 for d=3. In the fragile case, however, we argue that dimensionality dependence is weak, and show that for d=1, D ˜ ?-0.73. This scaling for the fragile case compares favorably with the results of a recent experimental study for a three-dimensional fragile glass former.

Jung, Younjoon; Garrahan, Juan P.; Chandler, David

2004-03-01

138

Anisotropic breakdown of Fermi liquid quasiparticle excitations in overdoped La2?xSrxCuO4  

NASA Astrophysics Data System (ADS)

High-temperature superconductivity emerges from an un-conventional metallic state. This has stimulated strong efforts to understand exactly how Fermi liquids breakdown and evolve into an un-conventional metal. A fundamental question is how Fermi liquid quasiparticle excitations break down in momentum space. Here we show, using angle-resolved photoemission spectroscopy, that the Fermi liquid quasiparticle excitations of the overdoped superconducting cuprate La1.77Sr0.23CuO4 is highly anisotropic in momentum space. The quasiparticle scattering and residue behave differently along the Fermi surface and hence the Kadowaki–Wood's relation is not obeyed. This kind of Fermi liquid breakdown may apply to a wide range of strongly correlated metal systems where spin fluctuations are present.

Chang, J.; Månsson, M.; Pailhès, S.; Claesson, T.; Lipscombe, O. J.; Hayden, S. M.; Patthey, L.; Tjernberg, O.; Mesot, J.

2013-10-01

139

Anisotropic breakdown of Fermi liquid quasiparticle excitations in overdoped La2-xSrxCuO4.  

PubMed

High-temperature superconductivity emerges from an un-conventional metallic state. This has stimulated strong efforts to understand exactly how Fermi liquids breakdown and evolve into an un-conventional metal. A fundamental question is how Fermi liquid quasiparticle excitations break down in momentum space. Here we show, using angle-resolved photoemission spectroscopy, that the Fermi liquid quasiparticle excitations of the overdoped superconducting cuprate La1.77Sr0.23CuO4 is highly anisotropic in momentum space. The quasiparticle scattering and residue behave differently along the Fermi surface and hence the Kadowaki-Wood's relation is not obeyed. This kind of Fermi liquid breakdown may apply to a wide range of strongly correlated metal systems where spin fluctuations are present. PMID:24096628

Chang, J; Månsson, M; Pailhès, S; Claesson, T; Lipscombe, O J; Hayden, S M; Patthey, L; Tjernberg, O; Mesot, J

2013-10-01

140

Spectroscopic investigation of liquid helium excited by a corona discharge: evidence for bubbles and ``red satellites''  

NASA Astrophysics Data System (ADS)

The establishment of corona discharges close to a point electrode under both negative and positive high voltage in normal liquid helium (LHe) at 4.2 K is reported. The experiments were carried out at constant temperature and pressures ranging from 0.1-10 MPa. Visible luminescence emitted from the zone close to the tip revealed lines due to excited He atoms and molecules. The molecular luminescence showed hot band emissions with vibrational levels populated up to v=2. Rotational temperatures of 800 K were estimated showing that the excitations do not thermalise. With increasing pressure the lines shifted to shorter wavelengths and became broader. The magnitude of the increase in width deviated from what is expected from the gas phase and from classical line broadening theory and rather showed similarities to the behavior of bubbles in LHe. The detailed analysis of the rotational line intensity distribution revealed the presence of an additional radiator at the long wavelength side of molecular bands that we tentatively assign to “red satellite” emission. For corona discharges with positive tip polarities both atomic and molecular lines showed “red satellite" bands with much larger intensity than for negative polarity. The origin of the red satellite and the polarity dependence is unclear yet.

Li, Z.-L.; Bonifaci, N.; Aitken, F.; Denat, A.; von Haeften, K.; Atrazhev, V. M.; Shakhatov, V. A.

2009-08-01

141

Non-linear seismic response of base-isolated liquid storage tanks to bi-directional excitation  

Microsoft Academic Search

Seismic response of the liquid storage tanks isolated by lead-rubber bearings is investigated for bi-directional earthquake excitation (i.e. two horizontal components). The biaxial force-deformation behaviour of the bearings is considered as bi-linear modelled by coupled non-linear differential equations. The continuous liquid mass of the tank is modelled as lumped masses known as convective mass, impulsive mass and rigid mass. The

M. K. Shrimali; R. S. Jangid

2002-01-01

142

Excitation of convective motions and surface hydrodynamic soliton-type waves in liquid crystals by a Gaussian laser beam  

SciTech Connect

The possibility of exciting convective motions with a toroidal symmetry in a disordered liquid-crystal cell with an open surface, which is locally heated by a Gaussian laser beam, is demonstrated experimentally. A perturbation of the free surface of the liquid crystal and a convective hydrodynamic motion are determined by temperature gradients. It is shown that a radial distribution of the director of a nematic liquid crystal appears in the convection region. Under certain experimental conditions, soliton-type hydrodynamic orientation waves are observed at the free surface of a nematic liquid crystal. It is found experimentally that the velocity of these waves is determined solely by the liquid-crystal parameters and is independent of the incident laser-radiation power. (interaction of laser radiation with matter. laser plasma)

Akopyan, R S; Alaverdyan, R B; Arakelyan, A G; Nersisyan, S Ts; Chilingaryan, Yu S [Department of Physics, Yerevan State University, Yerevan (Armenia)

2004-03-31

143

Fermi liquid theory for high temperature superconductors  

SciTech Connect

In this article the Fermi liquid theory of metals is discussed starting from Luttinger's theorem. The content of Luttinger's Theorem and its implications for microscopic theories of high temperature superconductors are discussed. A simple quasi-2d Fermi liquid theory is introduced and some of its properties are calculated. It is argued that a number of experiments on YBa/sub 2/Cu/sub 3/O/sub 6+x/, x > 0.5, strongly suggest the existence of a Fermi surface and thereby a Fermi liquid normal state. 25 refs., 1 fig.

Bedell, K.S.

1988-01-01

144

Emergence of the collective-response of granular solid - liquid mixtures to wave- pulse excitations  

NASA Astrophysics Data System (ADS)

The phenomenon of emergence of new properties observed in the collection of solid particles in liquid, due to pulse-wave excitations, can be found in many macroscopic systems. In this paper the uniform mixtures of solid spherical grains in water were subjected to high intensity, 60-Volts amplitude, pulsed -Ultrasonic waves of 45 kHz peak frequency. The observed response of the mixture was imbedded in the modified transmitted pulse, and could be extracted and compared to that of a reference pulse. Analysis of the results, in the frequency and time domains, includes; Fast Fourier Transform, amplitude and phase changes, and frequency dependent attenuation. The experimental findings and numerical results show that, the response of the mixture can be made independent of the scale, up to relatively small scale. The findings also show that, several collective- response to elastic wave propagation in the crystalline solids at the atomic scale, such as; cut-off frequency, tunneling effect, and absorption and conduction bands, can also have analogous ones in intermediary, and equivalences in these relatively simple mixtures.

Tavossi, Hasson M.

2013-03-01

145

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

National Technical Information Service (NTIS)

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 stan...

J. P. Hill

1996-01-01

146

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

Microsoft Academic Search

We analyze the non-Fermi-liquid (NFL) behavior of the fluctuating gap model (FGM) of pseudogap behavior in both one and two\\u000a dimensions. A detailed discussion of quasiparticle renormalization (Z-factor) is given, demonstrating a kind of marginal Fermi-liquid\\u000a or Luttinger-liquid behavior and topological stability of the bare Fermi surface (the Luttinger theorem). In the two-dimensional\\u000a case, we discuss the effective picture of

E. Z. Kuchinskii; M. V. Sadovskii

2006-01-01

147

High proton polarization in crystalline naphthalene by dynamic nuclear polarization with laser excitation at room temperature and liquid nitrogen temperature  

NASA Astrophysics Data System (ADS)

We have successfully polarized protons in naphthalene doped with pentacene at room temperature and liquid nitrogen temperature. Pentacene molecules have been excited with a laser beam and protons have been polarized dynamically in the triplet state of pentacene. We have obtained a polarization of about 13% at liquid nitrogen temperature in a field of about 3 kG with an N2 laser of about 150 mW. We expect to obtain a polarization higher than 30% with another type of laser.

Iinuma, M.; Shaké, I.; Takizawa, R.; Daigo, M.; Shimizu, H. M.; Takahashi, Y.; Masaike, A.; Yabuzaki, T.

1995-02-01

148

Simulation of electronic excitation in the liquid state by quantum mechanical charge field molecular dynamics  

NASA Astrophysics Data System (ADS)

The ab initio quantum mechanical charge field molecular dynamics simulation technique was applied for the first time to an electronically excited system, namely hydrated Li(I). This approach does not only provide data for the influence of electronic excitation on structure and composition of the hydrate, but also leads to a spectrum for the excitation band including rotational, translational and vibrational energy transfers. The first excitation band for Li(I) in water peaks at 13.1 eV. The excitation leads to reduced coordination numbers of first and second hydration shell and stabilises the first and labilises the second shell.

Bene, Gabriel E.; Hofer, Thomas S.; Randolf, Bernhard R.; Rode, Bernd M.

2012-01-01

149

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

PubMed

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. PMID:19123565

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

2008-12-01

150

Lowering the excitation threshold of a random laser using the dynamic scattering states of an organosiloxane smectic A liquid crystal  

NASA Astrophysics Data System (ADS)

Smectic A liquid crystals, based upon molecular structures that consist of combined siloxane and mesogenic moieties, exhibit strong multiple scattering of light with and without the presence of an electric field. This paper demonstrates that when one adds a laser dye to these compounds it is possible to observe random laser emission under optical excitation, and that the output can be varied depending upon the scattering state that is induced by the electric field. Results are presented to show that the excitation threshold of a dynamic scattering state, consisting of chaotic motion due to electro-hydrodynamic instabilities, exhibits lower lasing excitation thresholds than the scattering states that exist in the absence of an applied electric field. However, the lowest threshold is observed for a dynamic scattering state that does not have the largest scattering strength but which occurs when there is optimization of the combined light absorption and scattering properties.

Morris, Stephen M.; Gardiner, Damian J.; Qasim, Malik M.; Hands, Philip J. W.; Wilkinson, Timothy D.; Coles, Harry J.

2012-02-01

151

On the seismic behavior of cylindrical base-isolated liquid storage tanks excited by long-period ground motions  

Microsoft Academic Search

A common effective method to reduce the seismic response of liquid storage tanks is to isolate them at base using base-isolation systems. It has been observed that in many earthquakes, the foregoing systems significantly affect on the whole system response reduction. However, in exceptional cases of excitation by long-period shaking, the base-isolation systems could have adverse effects. Such earthquakes could

M. R. Shekari; N. Khaji; M. T. Ahmadi

2010-01-01

152

Ultrafast FRET in a room temperature ionic liquid microemulsion: a femtosecond excitation wavelength dependence study.  

PubMed

Fluorescence resonance energy transfer (FRET) from coumarin 480 (C480) to rhodamine 6G (R6G) is studied in a room temperature ionic liquid (RTIL) microemulsion by picosecond and femtosecond emission spectroscopy. The microemulsion is comprised of the RTIL 1-pentyl-3-methylimidazolium tetraflouroborate, [pmim][BF4], in TX-100/ benzene. We have studied the microemulsion with and without water. The time constants of FRET were obtained from the risetime of the acceptor (R6G) emission. In the RTIL microemulsion, FRET occurs on multiple time scales: 1, 250, and 3900 ps. In water containing RTIL microemulsion, the rise components are 1.5, 250, and 3900 ps. The 1 and 1.5 ps components are assigned to FRET at a close contact of donor and acceptor (RDA approximately 12 A). This occurs within the highly polar (RTIL/water) pool of the microemulsion. With increase in the excitation wavelength (lambdaex) from 375 to 435 nm, the relative contribution of the ultrafast component of FRET (1 ps) increases from 4% to 100% in the RTIL microemulsion and 12% to 100% in the water containing RTIL microemulsion. It is suggested that at lambdaex = 435 nm, mainly the highly polar RTIL pool is probed where FRET is very fast due to the close proximity of the donor and the acceptor. The very long 3900 ps (RDA approximately 45 A) component may arise from FRET from a donor in the outer periphery of the microemulsion to an acceptor in the polar RTIL pool. The 250 ps component (RDA approximately 29 A) is assigned to FRET from a donor inside the surfactant chains. PMID:19127996

Adhikari, Aniruddha; Das, Dibyendu Kumar; Sasmal, Dibyendu Kumar; Bhattacharyya, Kankan

2009-04-23

153

Breakdown of Fermi liquid in correlated electron systems  

Microsoft Academic Search

The standard description of metals is based on the Landau theory of Fermi systems (Fermi Liquid theory). This picture breaks down in one dimensional systems, which are instead described by the Luttinger Liquid theory. Actually, experimental evidence indicates that Fermi Liquid theory breaks down in a variety of physical systems, including superconducting cuprates.In the first part of this lecture we

Claudio Castellani; Carlo Di Castro

1999-01-01

154

Cryogenic exciter  

SciTech Connect

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

Bray, James William (Niskayuna, NY); Garces, Luis Jose (Niskayuna, NY)

2012-03-13

155

Electromagnetically excited resonator sensors for remote mass detection and liquid phase sensing  

Microsoft Academic Search

Electromagnetic excitation of acoustic resonator sensors is a novel method with distinct advantages over piezoelectric resonators. A much wider range of transducer materials can be utilized, and remote excitation of resonant vibrations in a wide variety of different mode shapes is possible. These resonant modes display similar quality factors and characteristics as piezoelectric transducers and can be applied for mass

Frieder Lucklum; Bernhard Jakoby

2007-01-01

156

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.

Khan, A. U.; Kasha, M.

1979-01-01

157

Lactone cleavage reaction kinetics of rhodamine dye at liquid/liquid interfaces studied by micro-two-phase sheath flow/two-photon excitation fluorescence microscopy.  

PubMed

Two-photon excitation fluorescence microscopy was combined with the two-phase microflow system in order to measure the fast interfacial reaction rate at liquid/liquid interfaces. The lactone cleavage kinetics of octadecylrhodamine B (C(18)RB) at the toluene/water and heptane/water interfaces was studied by this new method. The organic solution containing the nonfluorescent lactone of C(18)RB was made to flow as an inner flow with an aqueous outer sheath flow. The diameter of the inner flow was <20 microm. A focused fundamental beam of a Ti:sapphire pulse laser of 780 nm was irradiated to the interface, and emitted fluorescence from the fluorescent product was detected by a charge-coupled device (CCD) camera or a streakscope. The increase in the concentration of the fluorescent form of C(18)RB was measured along the interface of the inner flow of the toluene/water and heptane/water systems for 80 micros just after the contact of two phases. The analysis made by the time-dependent Langmuir adsorption model with the aid of the digital simulation method gave the cleavage reaction rate constants of the lactone form of C(18)RB at the liquid/liquid interfaces. PMID:15697274

Tokimoto, Takahira; Tsukahara, Satoshi; Watarai, Hitoshi

2005-02-15

158

Collective excitations in liquid D{sub 2} confined within the mesoscopic pores of a MCM-41 molecular sieve  

SciTech Connect

We present a comparative study of the excitations in bulk and liquid D{sub 2} confined within the pores of MCM-41. The material (Mobile Crystalline Material-41) is a silicate obtained by means of a template that yields a partially crystalline structure composed by arrays of nonintersecting hexagonal channels of controlled width having walls made of amorphous SiO{sub 2}. Its porosity was characterized by means of adsorption isotherms and found to be composed by a regular array of pores having a narrow distribution of sizes with a most probable value of 2.45 nm. The assessment of the precise location of the sample within the pores is carried out by means of pressure isotherms. The study was conducted at two pressures which correspond to pore fillings above the capillary condensation regime. Within the range of wave vectors where collective excitations can be followed up (0.3{<=}Q{<=}3.0 A{sup -1}), we found confinement brings forward a large shortening of the excitation lifetimes that shifts the characteristic frequencies to higher energies. In addition, the coherent quasielastic scattering shows signatures of reduced diffusivity.

Mondelli, C.; Gonzalez, M. A. [Institut Laue Langevin, B.P. 156x, 38042 Grenoble Cedex 9 (France); Albergamo, F. [European Synchrotron Radiation Facility, B.P. 220, F-38043 Grenoble Cedex (France); Carbajo, C. [Departamento de Quimica Inorganica, Facultad de Ciencias Quimicas, Universidad Complutense, E-28049 Madrid (Spain); Torralvo, M. J.; Enciso, E. [Departamento de Quimica Fisica I, Facultad de Ciencias Quimicas, Universidad Complutense, E-28049 Madrid (Spain); Bermejo, F. J. [C.S.I.C.- Department of Electricity and Electronics, University of the Basque Country, P.O. Box. 644, Bilbao 48080 (Spain); Fernandez-Perea, R.; Cabrillo, C. [Instituto de Estructura de la Materia, Consejo Superior de Investigaciones Cientificas, Serrano 123, Madrid 28006 (Spain); Leon, V.; Saboungi, M. L. [Centre de Recherche sur la Matiere Divisee, 1B rue de la Ferollerie 45071, Orleans Cedex 2 (France)

2006-03-01

159

Suppression of vortex-excited vibration of tall buildings using tuned liquid dampers  

Microsoft Academic Search

The objective of this paper is to study the control effects of rectangular TLDs installed on a tall building that vibrates due to vortex excitation. Optimal design properties of these TLDs and their control performance are first obtained using the characteristic equation of the TLD-building system. Wind tunnel experiments are performed on a scaled-down building model equipped with rectangular TLDs

C. C. Chang; M. Gu

1999-01-01

160

Hard-Sphere Approach to the Excitation Spectrum in Liquid Helium II.  

National Technical Information Service (NTIS)

The excitation spectrum of a Bose system of hard spheres is obtained in a high-density-calculation-including multiple scattering processes. The hard-sphere interaction is represented by a non-Hermitian pseudopotential constructed in a previous work, and t...

L. Liu L. S. Liu

1964-01-01

161

Edge excitations of paired fractional quantum Hall states  

NASA Astrophysics Data System (ADS)

The Hilbert spaces of the edge excitations of several ``paired'' fractional quantum Hall states, namely, the Pfaffian, Haldane-Rezayi, and 331 states, are constructed and the states at each angular momentum level are enumerated. The method is based on finding all the zero-energy states for those Hamiltonians for which each of these known ground states is the exact, unique, zero-energy eigenstate of lowest angular momentum in the disk geometry. For each state, we find that, in addition to the usual bosonic charge-fluctuation excitations, there are fermionic edge excitations. The wave functions for each case have a similar form, related to Slater determinants, and the edge states satisfy a ``projection rule,'' that the parity of the number of fermions added to the edge equals the parity of the charge added. The edge states can be built out of quantum fields that describe the fermions, in addition to the usual scalar bosons (or Luttinger liquids) that describe the charge fluctuations. The fermionic fields in the Pfaffian and 331 cases are a noninteracting Majorana (i.e., real Dirac) and Dirac field, respectively. For the Haldane-Rezayi state, the field is an anticommuting scalar. For this system, we exhibit a chiral Lagrangian that has manifest SU(2) symmetry, but breaks Lorentz invariance, because of the breakdown of the spin-statistics connection implied by the scalar nature of the field and the positive-definite norm on the Hilbert space. Finally, we consider systems on a cylinder, where the fluid has two edges, and construct the sectors of zero-energy states, discuss the projection rules for combining states at the two edges, and calculate the partition function for each edge excitation system at finite temperature in the thermodynamic limit. The corresponding theory for the hierarchy and its generalizations is also given. It is pointed out that the conformal field theories for the edge states are examples of orbifold constructions. Two appendixes contain technical details.

Milovanovi?, M.; Read, N.

1996-05-01

162

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

163

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

Microsoft Academic Search

The transfer of an electron from a donor to an acceptor is the fundamental step in a wide range of chemical and biological processes. As a result, electron-transfer reactions have been the focus of numerous theoretical and experimental efforts aimed at understanding the kinetics and mechanism of the transfer event. Liquid solvents are an important medium for electron-transfer processes. The

Alexei A. Goun

2008-01-01

164

Excitations of nanoscale quantum liquids under pressure and the Bose glass phase  

NASA Astrophysics Data System (ADS)

We present neutron scattering measurements of the dynamic structure factor of liquid helium confined to nanoscales in 25 and 34Å mean pore diameter porous media over a range of pressures and temperatures. At low temperature and low pressure we observe well-defined phonon-roton (P-R) modes characteristic of liquid helium containing Bose-Einstein condensation (BEC). As pressure is increased above 25 bars, we observe that the high energy P-R modes broaden and become unobservable. At pressure p=36.3-36.8bars we observe loss of all modes, including the roton. The observation of modes up to 36.3-36.8 bars indicates that there is liquid containing BEC in the gelsils up to this pressure. The loss of modes at 36.3-36.8 bars indicates loss of BEC in the liquid or significant solidification in the gelsils at this pressure. At a pressure of 31.2 bars, we observe well-defined P-R modes up to T?1.4K but loss of all modes above this temperature. At p?0 , we have previously observed modes up to T?=2.17K . Yamamoto have reported superfluidity in the same 25Å gelsil up to a pressure pc=34bars at T?0K and to a maximum temperature of Tc=1.3K at p?0 . The transition at pc=34bars and T?0K was interpreted as a quantum phase transition. The present observation of P-R modes at temperatures well above Tc (and pressures slightly above pc ) indicates that there is a phase containing BEC above Tc (pc) that is not superfluid. This is interpreted as a Bose glass phase containing islands of BEC that support P-R modes separated by normal liquid so that there is no phase coherence across the sample as needed for superflow. The Bose glass phase lies between the superfluid and normal liquid at all temperatures and pressures. Measurements of the static structure factor indicate that freezing in the gelsils is predominantly to an amorphous solid.

Bossy, Jacques; Pearce, Jonathan V.; Schober, Helmut; Glyde, Henry R.

2008-12-01

165

Raman spectroscopy of a coal liquid shows that fluorescence interference is minimized with ultraviolet excitation  

SciTech Connect

The first ultraviolet resonance Raman measurements of a coal liquid are reported. The spectra detail the presence of numerous polycyclic aromatic hydrocarbons with ring systems similar to those of naphthalene, fluorene, phenanthrene, pyrene, and triphenylene. The ultraviolet resonance Raman measurements of this highly complex sample show no significant interference from fluorescence. The lack of fluorescence interference and the high selectivity indicate that ultraviolet resonance Raman spectroscopy is a powerful new technique for characterizing highly complex samples and mixtures. 11 references, 2 figures.

Asher, S.A.; Johnson, C.R.

1984-07-20

166

Raman spectroscopy of a coal liquid shows that fluorescence interference is minimized with ultraviolet excitation  

SciTech Connect

The first ultraviolet resonance Raman measurements of a coal liquid are reported. The spectra detail the presence of numerous polycyclic aromatic hydrocarbons with ring systems similar to those of naphthalene, fluorene, phenanthrene, pyrene, and triphenylene . The ultraviolet resonance Raman measurements of this highly complex sample show no significant interference from fluorescence. The lack of fluorescence interference and the high selectivity indicate that ultraviolet resonance Raman spectroscopy is a powerful new technique for characterizing highly complex samples and mixtures.

Asher, S.A.; Johnson, C.R.

1984-07-20

167

Photo-excited states in germanium at liquid-helium temperatures  

SciTech Connect

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

Culbertson, J.C.

1982-12-01

168

On the fractional statistics of excitations in doped spin liquid states  

NASA Astrophysics Data System (ADS)

We study a generalized t-J model for lightly doped Mott insulators. The fractional statistics of both spinons and holons are discussed in a U(1) gauge theory. We explicitly derive the Chern-Simons term in the chiral spin liquid. The effective theory of holons is that of a charged scalar field coupled to a U(1) gauge field with a Chern-Simons term. We derive from the microscopic model, using the canonical quantization method, the anyon Hamiltonian of Fetter, Hanna and Laughlin.

Zou, Zhou

1989-12-01

169

Possible Fermi liquid in the lightly doped Kitaev spin liquid.  

PubMed

We study the lightly doped Kitaev spin liquid (LDKSL) and find it to be the Fermi liquid. The LDKSL satisfies the two key properties of the standard Landau Fermi liquid: the low-energy quasiparticles are well defined and the Fermi sea has the quantized volume determined by Luttinger's theorem. These features can be observed in angle-resolved photoemission spectroscopy measurements. Meanwhile, the LDKSL has the topological Kitaev spin liquid surrounding the Fermi sea. So the LDKSL violates the Wiedemann-Franz law and has a large Wilson ratio. These results have the potential experimental verifiability in iridates upon doping. PMID:23003650

Mei, Jia-Wei

2012-05-30

170

Boson localization and excitations of liquid {sup 4}He confined in gelsil  

SciTech Connect

We present neutron scattering measurements of the phonon-roton (P-R) modes of liquid {sup 4}He at saturated vapor pressure confined in 44 A mean pore diameter gelsil in the wave vector range 0.4{<=}Q{<=}2.15 A{sup -1}. Layer modes, modes which propagate in the liquid layers adjacent to the porous media walls, were also observed at wave vectors in the roton region (Q{approx_equal}1.95 A{sup -1}) but not at Q < or approx. 1.7 A{sup -1}. The first goal is to document the filling dependence of the dynamic response and of the P-R mode energies and widths more systematically than has been done in the past. As the gelsil is filled with {sup 4}He, the P-R and layer modes are first observed at a fractional filling of f=76% at low temperature (T=0.4 K). At fillings f=76%, the P-R mode energies lie below the bulk superfluid {sup 4}He values in the wave vector range 0.4{<=}Q{<=}1.7 A{sup -1}, especially at Q{approx_equal}1.1 A{sup -1}, as observed in helium films. As filling is increased, the intensity in the P-R mode increases markedly and the P-R mode energies move toward bulk superfluid values taking bulk values at full filling. The second goal is to determine the temperature dependence of the intensity in the P-R modes in a media in which the superfluid-normal transition temperature T{sub c}=1.92 K is independently known and lies well below the bulk liquid value T{sub {lambda}}=2.17 K. As temperature is increased, the intensity in the P-R and layer modes decreases. However, a well-defined P-R mode is observed at temperatures up to T{approx_equal}2.15 K, above T{sub c}=1.92 K. Since well-defined modes exist because there is Bose-Einstein condensation (BEC), this suggests that there is BEC above T{sub c}, probably localized. Localized BEC appears to exist up to T{approx_equal}T{sub {lambda}}.

Albergamo, Francesco [European Synchrotron Radiation Facility, Boite Postale 220, F-38043 Grenoble Cedex (France); Bossy, Jacques [Centre de Recherche sur les Tres Basses Temperatures, CNRS, BP 166, 38042 Grenoble Cedex 9 (France); Pearce, Jonathan V. [Institut Laue-Langevin, BP 156, 38042 Grenoble (France); Department of Physics and Astronomy, University of Delaware, Newark, Delaware 19716-2570 (United States); Schober, Helmut [Institut Laue-Langevin, BP 156, 38042 Grenoble (France); Glyde, Henry R. [Department of Physics and Astronomy, University of Delaware, Newark, Delaware 19716-2570 (United States)

2007-08-01

171

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

172

NMR proton spin dynamics in thermotropic liquid crystals subject to multipulse excitation  

NASA Astrophysics Data System (ADS)

Previous experiments of NMR spin-lattice relaxation times as a function of the Larmor frequency, as measured with the field-cycling technique (FC), were shown to be very useful to disentangle the various molecular motions, both local and collective, that dominate the relaxation in different time scales in liquid crystals. However, there are many examples where the known theoretical models that represent the molecular relaxation mechanisms cannot be fitted to the experimental trend in the region of low fields, making it difficult to obtain reliable values for the spectral densities involved, especially for the cooperative motions which dominate at low frequencies. In some cases, these anomalies are loosely ascribed to “local-field” effects but, to our knowledge, there is not a detailed explanation about the origin of these problems nor the range of frequencies where they should be expected. With the aim of isolating the dipolar effects from the influence of molecular dynamics, and taking into account the previous results in solids, in this work we investigate the response of the proton spin system of thermotropic liquid crystals 4-pentyl-4'-cyanobiphenyl (5CB) and 4-octyl-4'-cyanobiphenyl (8CB) in nematic and smectic A phases, due to the NMR multipulse sequence 90?y-(?-?x-?)N. The nuclear magnetization presents an early transient period characterized by strong oscillations, after which a quasistationary state is attained. Subsequently, this state relaxes towards internal equilibrium over a time much longer than the transverse relaxation time T2. As occurs in solids, the decay time of the quasistationary state T2e presents a minimum when the pulse width ?x and the offset of the radiofrequency are set to satisfy resonance conditions (spin-lock). When measured as a function of the pulse spacing ? in “on-resonance” experiments, T2e shows the behavior expected for cross relaxation between the effective Zeeman and dipolar reservoirs, in accordance with the thermodynamic theory previously developed for solids. Particularly, for values of ? comparable with T2, the relaxation rate follows a power law T2e??-2, in all the observed cases, for the resonance conditions ?x=?/3 and equivalent frequency ?e=?/3?. When ? is similar to or greater than typical dipolar periods, the relaxation rate becomes constant and for ? much shorter than T2, the thermodynamic reservoirs get decoupled. These experiments confirm that the thermodynamic picture is valid also in liquid crystals and the cross relaxation between the reservoirs can be detected without interference with spin-lattice relaxation effects. Accordingly, this technique can be used to estimate the frequency range, where cross-relaxation effects can be expected when Zeeman and dipolar reservoirs are put in thermal contact with each other and with the lattice, as in FC experiments. In particular, the present results allow us to associate the anomalies observed in low-field spin-lattice relaxation with nonadiabatic energy exchange between the reservoirs.

Acosta, R. H.; Zamar, R. C.; Monti, G. A.

2003-10-01

173

INTERACTION OF LASER RADIATION WITH MATTER. LASER PLASMA: Excitation of convective motions and surface hydrodynamic soliton-type waves in liquid crystals by a Gaussian laser beam  

NASA Astrophysics Data System (ADS)

The possibility of exciting convective motions with a toroidal symmetry in a disordered liquid-crystal cell with an open surface, which is locally heated by a Gaussian laser beam, is demonstrated experimentally. A perturbation of the free surface of the liquid crystal and a convective hydrodynamic motion are determined by temperature gradients. It is shown that a radial distribution of the director of a nematic liquid crystal appears in the convection region. Under certain experimental conditions, soliton-type hydrodynamic orientation waves are observed at the free surface of a nematic liquid crystal. It is found experimentally that the velocity of these waves is determined solely by the liquid-crystal parameters and is independent of the incident laser-radiation power.

Akopyan, R. S.; Alaverdyan, R. B.; Arakelyan, A. G.; Nersisyan, S. Ts; Chilingaryan, Yu S.

2004-03-01

174

Bose Einstein condensation: Its role in the excitations of liquid helium and in trapped Bose gases  

NASA Astrophysics Data System (ADS)

The role of Bose-Einstein condensation (BEC) in determining the properties of Bose systems at ultracold temperatures is investigated. First, we present a model of the dynamic structure factor S(Q,o) of liquid 4He as observed in inelastic neutron scattering measurements beyond the roton (Q ? 2.0 A-1). We separate the dynamic susceptibility into chi = chiS + chi'R. chi S involves states in the condensate and chi' R states above the condensate only. We find that the weight of chiS scales with the condensate fraction n0(T) and vanishes at Tlambda. chi' R is broad and largely temperature independent and a low energy intensity broadening arises from the thermal broadening of the phonon-roton (p-r) modes. Secondly, we investigate ultracold Bose gases with repulsive and attractive interactions confined in a spherical harmonic trap over a broad range of densities using model potentials and variational Monte Carlo (VMC) at T = 0 K. In the case of repulsive interactions, the Bosons are represented by hard spheres (HS)s interacting by a HS potential. We change the densities of the Bosons by increasing the s-wave scattering length a. We find that the VMC total and VMC condensate density distributions are similar in shape, they are flat nearly at the higher densities. Further the Thomas-Fermi approximation becomes invalid and the condensate is substantially depleted at the higher densities. In the case of attractive interactions, we model the interactions by a hard core square well (HCSW). We change the densities of these systems by keeping the hard core diameter, a c, fixed and increasing the potential depth V 0 or by increasing both of them simultaneously while keeping a fixed. We find that a Bose gas with attractive interactions undergoes a first order phase transition from the gas to the liquid state at a value of N|a| ? 0.574 in agreement with the value predicted by Gross-Pitaevskii (GP) theory. The condensate depletion is mainly driven by the HC diameter in the presence of an attractive well. The scattering length is a useful representation of the HCSW at the low densities, but at the higher densities the HCSW is not represented well anymore by the scattering length.

Sakhel, Asaad R.

175

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

176

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

177

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

SciTech Connect

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

Dudek, J.

1987-01-01

178

Observation of particle hole asymmetry and phonon excitations in non-Fermi-liquid systems: A high-resolution photoemission study of ruthenates  

NASA Astrophysics Data System (ADS)

We investigate the temperature evolution of the electronic states in the vicinity of the Fermi level of a non-Fermi-liquid (NFL) system, CaRuO3 using ultra high-resolution photoemission spectroscopy; isostructural SrRuO3 exhibiting Fermi-liquid behavior despite similar electron interaction parameters as that of CaRuO3, is used as a reference. High-energy resolution in this study helps to reveal particle-hole asymmetry in the excitation spectra of CaRuO3 in contrast to that in SrRuO3. In addition, we observe signature of phonon excitations in the photoemission spectra of CaRuO3 at finite temperatures while these are weak in SrRuO3.

Maiti, K.; Singh, R. S.; Medicherla, V. R. R.

2007-04-01

179

Interplay of Coulomb blockade and Aharonov-Bohm resonances in a Luttinger liquid  

Microsoft Academic Search

We consider a ring of strongly interacting electrons connected to two external leads by tunnel junctions. By studying the positions of conductance resonances as a function of gate voltage and magnetic flux, the interaction parameter g can be determined experimentally. For a finite ring the minimum conductance is strongly influenced by device geometry and electron-electron interactions. In particular, if the

Jari M. Kinaret; Mats Jonson; Robert I. Shekhter; Sebastian Eggert

1998-01-01

180

Spin resonance in a Luttinger liquid with spin-orbit interaction  

NASA Astrophysics Data System (ADS)

Spin-orbit interaction in quantum wires leads to a spin resonance at low temperatures, even in the absence of an external dc magnetic field. We study the effect of electron-electron interaction on the resonance. This interaction is strong in quantum wires. We show that the electron-electron interaction changes the shape of the resonance curve and produces an additional cusp at the plasmon frequency. However, except for very strong electron-electron interaction these changes are weak since this interaction by itself does not break the spin-rotation symmetry that is violated weakly by the spin-orbit interaction and external magnetic field.

Tretiakov, O. A.; Tikhonov, K. S.; Pokrovsky, V. L.

2013-09-01

181

How Does a Quadratic Term in the Energy Dispersion Modify the Single-Particle Green's Function of the Tomonaga-Luttinger Model?  

NASA Astrophysics Data System (ADS)

We calculate the effect of a quadratic term in the energy dispersion on the low-energy behavior of the Green's function of the spinless Tomonaga-Luttinger model (TLM). Assuming that for small wave-vectors q=k-kF the fermionic excitation energy relative to the Fermi energy is vFq+q2/(2m), we explicitly calculate the single-particle Green's function for finite but small values of ?=qc/(2kF). Here kF is the Fermi wave-vector, qc is the maximal momentum transfered by the interaction, and vF=kF/m is the Fermi velocity. Assuming equal forward scattering couplings g2=g4, we find that the dominant effect of the quadratic term in the energy dispersion is a renormalization of the anomalous dimension. In particular, at weak coupling the anomalous dimension is ~ {? }=? (1-2? 2? ), where ? is the anomalous dimension of the TLM. We also show how to treat the change of the chemical potential due to the interactions within the functional bosonization approach in arbitrary dimensions.

Busche, Tom; Kopietz, Peter

182

Quantum quench in the Luttinger model with finite temperature initial state  

NASA Astrophysics Data System (ADS)

We study the nonequilibrium dynamics of the Luttinger model after a quantum quench, when the initial state is a finite temperature thermal equilibrium state. The diagonal elements of the density matrix in the steady state show thermal features for high temperature initial states only, otherwise they retain highly nonthermal character. The time evolution of Uhlmann fidelity, which measures the distance between the time evolved and initial states, is evaluated for arbitrary initial temperatures and quench protocols. In the long time limit, the overlap between the time evolved and initial system decreases exponentially with the temperature with a universal prefactor. Within perturbation theory, the statistics of final total energy and work are numerically evaluated in the case of a sudden quench, which yield identical distributions at zero temperature. In both statistics, temperature effects are more significant in small systems. The Dirac-? peak at the adiabatic ground state energy remains present in the probability distribution of the total energy, but disappears from the work distribution at nonzero initial temperatures.

Bácsi, Ádám; Dóra, Balázs

2013-10-01

183

Laser study of the time dependence of induced absorption in a liquid excited by uranium fission fragments  

SciTech Connect

The results of 1.05-{mu}m laser measurements of optical properties of the POCl{sub 3} - SnCl{sub 4} - UO{sub 2}{sup 2+} liquid containing vapour bubbles generated by the fission fragments of {sup 235}U nuclei formed upon irradiation of this liquid by neutrons in a BARS-6 pulsed reactor are presented. The average size of a bubble and its mean lifetime are obtained from experiments. The effect of pressure on the bubble size is studied. It is found that the lifetime of a bubble increases with increasing the concentration of molecular chlorine in the liquid due to its radiolysis induced by fission fragments. (laser applications and other topics in quantum electronics)

Seregina, E A; Dobrovol'skii, A F; D'yachenko, P P; Lapidus, V I; Seregin, A A; Tikhonov, G V [State Scientific Center of the Russian Federation 'A.I. Leipunski Institute for Physics and Power Engineering', Obninsk, Kaluga Region (Russian Federation)

2003-10-31

184

Validity of Fermi-Liquid Description of Low-Energy Magnetic Excitation in Electron-Doped Cuprate Superconductors  

NASA Astrophysics Data System (ADS)

The spin-fluctuation spectrum of electron-doped cuprate superconductors is calculated using the single-band Hubbard model with realistic tight-binding parameters and the fluctuation--exchange approximation. No strong incommensurate wings are found in the superconducting state in agreement with experiments. Our results imply that the magnetic response of electron-doped cuprates can be explained with the conventional Fermi-liquid approach. We also give a detailed comparison with a previous work, where the spin-fluctuation spectrum calculated with the random phase approximation was found to be dominated by incommensurate wings and thereby the Fermi-liquid approach was seriously questioned.

Mutou, Tetsuya; Hirashima, Dai S.

2013-09-01

185

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

2013-06-22

186

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

NASA Astrophysics Data System (ADS)

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

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

187

A comparison between different semiclassical approximations for optical response functions in nonpolar liquid solution. II. The signature of excited state dynamics on two-dimensional spectra  

NASA Astrophysics Data System (ADS)

Optical response functions are known to reflect quantum dynamics in a superposition state and as such, lack a well-defined classical limit. In a previous paper we considered the importance of accounting for the quantum nature of the dynamics by comparing the linear absorption spectrum and homodyne-detected time-integrated two-pulse photon-echo signal as calculated via the semiclassical forward-backward approach, linearized semiclassical approach, and standard approach which is based on equilibrium ground state dynamics [Shi and Geva, J. Chem. Phys. 122, 064506 (2005)]. In the present paper, we extend the comparison to the case of heterodyne-detected and time-resolved nonlinear time-domain rephasing and nonrephasing signals generated in three-pulse experiments and the corresponding frequency-domain two-dimensional spectra. The comparison is performed in the context of a two-state chromophore solvated in a nonpolar liquid. It is shown that the inherent insensitivity of the standard method to the nonequilibrium dynamics on the excited state potential surface gives rise to two-dimensional spectra which are symmetrical relative to the diagonal. In contrast, accounting for the effect of nonequilibrium excited state dynamics, as is the case within the forward-backward and linearized semiclassical methods, is found to give rise to two-dimensional spectra that become increasingly asymmetrical relative to the diagonal as the waiting time between the second and third pulses becomes larger. It is argued that the emergence of the asymmetry provides a useful probe of nonequilibrium solvation on the excited state potential surface.

Shi, Qiang; Geva, Eitan

2008-09-01

188

Bose-Fermi pairs in a mixture and the Luttinger theorem within a Nozières-Schmitt-Rink-like approach  

NASA Astrophysics Data System (ADS)

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

Sogo, T.; Schuck, P.; Urban, M.

2013-08-01

189

Effect of long-range interactions on the Kohn-Luttinger mechanism of the cooper instability in the Shubin-Vonsowsky model  

NASA Astrophysics Data System (ADS)

The problem of Cooper instability is studied by implementing the Kohn-Luttinger mechanism in the framework of the Shubin-Vonsowsky model taking into account the intersite Coulomb interactions within the first and second coordination spheres. It is shown that the Kohn-Luttinger renormalization for the effective interaction in the second-order terms of perturbation theory, as well as the inclusion of intersite hoppings in the second and third coordination spheres, significantly affects the interplay between the superconducting phases with d xy -, p-, s-, and d_{x^2 - y^2 }-wave symmetries of the order parameter.

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

2013-04-01

190

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

191

Evaluation of the Alignment of Liquid Crystal Molecules on SiO2 Alignment Layer by Attenuated Total Reflection Method Utilizing Surface Plasmon and Guided Wave Excitation Modes  

NASA Astrophysics Data System (ADS)

In this study, we report on the evaluation of tilt angles of liquid crystal (LC) molecules near the surface of SiO2 alignment layers and in the whole cell when constant voltages are applied. A LC molecule, 4-cyano-4'n-pentylbiphenyl, was used in this study. The LC cell consisted of Au (50nm) / SiO2 (30nm) /LC (3 ?m)/ SiO2 (30nm) / Au (100nm) system. SiO2 alignment layers were obliquely evaporated on both Au surfaces. Surface plasmon resonance and guided waveguide excitation modes in attenuated total reflection configuration were used to monitor the alignment property of LC molecules adjacent to the surface and the bulk in the LC cell. In the ATR angular scan properties, the theoretical fittings agreed well with the experimental data on the assumption of simplified 5 LC layers model. The profile of the tilt angles from the surface to inside the cells was obtained by the theoretical fitting. In comparison with the internal bulk region, LC molecules near the surface required higher voltages to change their tilt angles toward vertical direction. As demonstrated in this report, this technique should provide the useful information to understand the interfacial phenomena for LC displays.

Ikarashi, Aya; Baba, Akira; Shinbo, Kazunari; Kato, Keizo; Kaneko, Futao

192

Application of a temperature-dependent liquid-drop model to dynamical Langevin calculations of fission-fragment distributions of excited nuclei  

NASA Astrophysics Data System (ADS)

A stochastic approach to fission dynamics based on three-dimensional Langevin equations was applied to calculation of the mass-energy and angular distributions of fission fragments. The dependence of the mass-energy distribution parameters on the angular momentum and the anisotropy of the fission-fragment angular distribution on excitation energy have been studied in a wide range of the fissility parameter. A temperature-dependent finite-range liquid-drop model was used in a consistent way to calculate the functional of the Helmholtz free energy and level-density parameter. The modified one-body mechanism of nuclear dissipation (the so-called surface-plus-window dissipation) was used to determine the dissipative forces in Langevin equations. The evaporation of light prescission particles was taken into account on the basis of a statistical model combined with Langevin dynamics. The calculated parameters of the mass-energy distribution and their angular dependencies are in good quantitative agreement with the available experimental data at the value of the reduction coefficient of the contribution from the wall formula equal to 0.25. Analysis of the anisotropy of the fission-fragment angular distribution performed with the saddle-point transition state model and scission-point transition state model indicates that it is necessary to take into account the dynamical aspects of the fission-fragment angular distribution formation.

Ryabov, E. G.; Karpov, A. V.; Nadtochy, P. N.; Adeev, G. D.

2008-10-01

193

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

NASA Astrophysics Data System (ADS)

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

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

2006-09-01

194

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

SciTech Connect

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

Kuchinskii, E. Z.; Sadovskii, M. V. [Russian Academy of Sciences, Institute for Electrophysics (Russian Federation)], E-mail: sadovski@iep.uran.ru

2006-09-15

195

Liquid-Gas Phase Transition in Nuclear Matter Within a Correlated Approach  

NASA Astrophysics Data System (ADS)

The existence of a liquid-gas phase transition for hot nuclear systems close to saturation densities is an interesting prediction of finite temperature nuclear many-body theory. We have applied the realistic Self-Consistent Green's Function's (SCGF) method together with the Luttinger-Ward (LW) formalism to the study of the thermodynamical (TD) properties of infinite symmetric nuclear matter. We compare our results with those obtained within the Brueckner-Hartree-Fock (BHF) theory and find substantial differences.

Rios, A.; Polls, A.; Ramos, A.; Müther, H.

2008-06-01

196

Dynamical functions of a 1D correlated quantum liquid  

NASA Astrophysics Data System (ADS)

The dynamical correlation functions in one-dimensional electronic systems show power-law behaviour at low energies and momenta close to integer multiples of the charge and spin Fermi momenta. These systems are usually referred to as Tomonaga-Luttinger liquids. However, near well defined lines of the (k,?) plane the power-law behaviour extends beyond the low-energy cases mentioned above, and also appears at higher energies, leading to singular features in the photoemission spectra and other dynamical correlation functions. The general spectral-function expressions derived in this paper were used in recent theoretical studies of the finite-energy singular features in photoemission of the organic compound tetrathiafulvalene-tetracyanoquinodimethane (TTF-TCNQ) metallic phase. They are based on a so-called pseudofermion dynamical theory (PDT), which allows us to systematically enumerate and describe the excitations in the Hubbard model starting from the Bethe ansatz, as well as to calculate the charge and spin object phase shifts appearing as exponents of the power laws. In particular, we concentrate on the spin-density m\\rightarrow 0 limit and on effects in the vicinity of the singular border lines, as well as close to half filling. Our studies take into account spectral contributions from types of microscopic processes that do not occur for finite values of the spin density. In addition, the specific processes involved in the spectral features of TTF-TCNQ are studied. Our results are useful for the further understanding of the unusual spectral properties observed in low-dimensional organic metals and also provide expressions for the one- and two-atom spectral functions of a correlated quantum system of ultracold fermionic atoms in a 1D optical lattice with on-site two-atom repulsion.

Carmelo, J. M. P.; Bozi, D.; Penc, K.

2008-10-01

197

Solvation-driven excited-state dynamics of [Re(4-Et-Pyridine)(CO)3(2,2'-bipyridine)]+ in imidazolium ionic liquids. A time-resolved infrared and phosphorescence study.  

PubMed

Excited-state dynamics of [Re(Etpy)(CO)3(bpy)]+ was studied in three imidazolium ionic liquids by time-resolved IR and emission spectroscopy on the picosecond to nanosecond time scale. Low-lying excited states were characterized by TD-DFT calculations, which also provided molecular dipole moment vectors in the relevant electronic states. TRIR spectra in ionic liquids show initial populations of two excited states: predominantly bpy-localized 3IL and 3MLCT, characterized by nu(CO) bands shifted to lower and higher frequencies, respectively, relative to the ground state. Internal conversion of 3IL to the lowest triplet 3MLCT occurred on a time scale commensurate with solvent relaxation. The nu(CO) IR bands of the 3MLCT state undergo a dynamic shift to higher wavenumbers during relaxation. Its three-exponential kinetics were determined and attributed to vibrational cooling (units of picoseconds), energy dissipation to the bulk solvent (tens of picoseconds), and solvent relaxation, the lifetime of which increases with increasing viscosity: [EMIM]BF4 (330 ps) < [BMIM]BF4 (470 ps) < [BMIM]PF6 (1570 ps). Time-resolved phosphorescence spectra in [BMIM]PF6 show a approximately 2 ns drop in intensity due to the 3IL --> 3MLCT conversion and a dynamic Stokes shift to lower energies with a lifetime decreasing from 1.8 ns at 21 degrees C to 1.1 ns at 37 degrees C, due to decreasing viscosity of the ionic liquid. It is proposed that solvent relaxation predominantly involves collective translational motions of ions. It drives the 3IL --> 3MLCT conversion, increases charge reorganization in the lowest excited-state 3MLCT, and affects vibrational anharmonic coupling, which together cause the dynamic shift of excited-state IR bands. TRIR spectroscopy of carbonyl-diimine complexes emerges as a new way to investigate various aspects of solvation dynamics, while the use of slowly relaxing ionic liquids offers new insight into the photophysics of Re(I) carbonyl polypyridyls. PMID:18373366

Blanco-Rodríguez, Ana Maria; Ronayne, Kate L; Zalis, Stanislav; Sýkora, Jan; Hof, Martin; Vlcek, Antonín

2008-03-29

198

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.

1998-01-01

199

Anisotropic Fermi surfaces and Kohn-Luttinger superconductivity in two dimensions  

SciTech Connect

The instabilities induced on a two-dimensional system of correlated electrons by the anisotropies of its Fermi line are analyzed on general grounds. Simple scaling arguments allow to predict the opening of a superconducting gap with a well-defined symmetry prescribed by the geometry of the Fermi line. The same arguments predict a critical dimension of 3/2 for the transition of the two-dimensional system to non-Fermi liquid behavior. The methods are applied to the t-t{prime} Hubbard model in a wide range of dopings.

Gonzalez, J.; Guinea, F.; Vozmediano, M.A.H.

1999-08-10

200

Effect of time profile of laser pulse on the excitation of sound signals in a liquid with a series of laser pulses  

Microsoft Academic Search

We have studied the sound generation with high repetition rate pulsed laser. We have solved the inhomogeneous wave equation for acoustic pressure in a liquid generated by a laser, using Green's function formalism and convolution technique. To obtain the maximum pressure of the sound waves, we found the conditions on repetition rate and on period of laser pulse of various

V. K. Sayal; L. L. Yadav; K. P. Maheshwari

2011-01-01

201

Effect of time profile of laser pulse on the excitation of sound signals in a liquid with a series of laser pulses  

Microsoft Academic Search

We have studied the sound generation with high repetition rate pulsed laser. We have solved the inhomogeneous wave equation for acoustic pressure in a liquid generated by a laser, using Green’s function formalism and convolution technique. To obtain the maximum pressure of the sound waves, we found the conditions on repetition rate and on period of laser pulse of various

V. K. Sayal; L. L. Yadav; K. P. Maheshwari

2011-01-01

202

Collective excitations of helium clusters  

SciTech Connect

The excitation spectra of compressional modes of {sup 4}He{sub {ital N}}, {ital N}=20, 70, and 240, clusters at 0 K are calculated by treating the cluster as a quantum liquid drop. The spectrum of {ital N}=240 strongly resembles that of liquid helium with a visible roton structure, while for {ital N}=20 no roton minimum is seen and {ital N}=70 shows a weak minimum. Implications of these findings for superfluidity in helium clusters are discussed.

Rama Krishna, M.V.; Whaley, K.B. (Department of Chemistry, University of California, Berkeley, California 94720 (USA))

1990-03-05

203

Evaluation of the Alignment of Liquid Crystal Molecules on SiO2 Alignment Layer by Attenuated Total Reflection Method Utilizing Surface Plasmon and Guided Wave Excitation Modes  

Microsoft Academic Search

In this study, we report on the evaluation of tilt angles of liquid crystal (LC) molecules near the surface of SiO2 alignment layers and in the whole cell when constant voltages are applied. A LC molecule, 4-cyano-4'n-pentylbiphenyl, was used in this study. The LC cell consisted of Au (50nm) \\/ SiO2 (30nm) \\/LC (3 mum)\\/ SiO2 (30nm) \\/ Au (100nm)

Aya Ikarashi; Akira Baba; Kazunari Shinbo; Keizo Kato; Futao Kaneko

2010-01-01

204

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

205

Excited Delirium  

PubMed Central

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

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

2011-01-01

206

Excited baryons  

SciTech Connect

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

Mukhopadhyay, N.C.

1986-01-01

207

Excite's Channels  

NSDL National Science Digital Library

Whatever your opinion about the television-ization of the Internet, channels are coming to a search engine near you. Excite is the latest service to reorganize its content into channels (currently fourteen, from Arts & Entertainment to Travel & Regional). The search interface Excite users have come to know is still available, but many of the other services have been integrated into the channel lineup. NewsTracker, for example (discussed in the February 7, 1997 Scout Report) will show up both in My Channel (a customizable page with content tailored to individual tastes through the magic of cookies) and in the News channel. Users of NewsTracker in its previous incarnation will find their settings still intact when they visit the News channel. Each channel page offers current headlines, Excite services, chat and bulletin boards, and guided web tours, among other resources. If you know exactly what you're looking for, stick to the search interface; if you're in a browsing mood, check out the channels.

208

Deconfined fractionally charged excitation in any dimensions  

NASA Astrophysics Data System (ADS)

An exact incompressible quantum liquid is constructed at the filling factor 1/m2 in the square lattice. It supports deconfined fractionally charged excitation. At the filling factor 1/m2, the excitation has fractional charge e/m2, where e is the electric charge. This model can be easily generalized to the n-dimensional square lattice (integer lattice), where the charge of excitations becomes e/mn.

Chern, Chyh-Hong; Huang, Po-Hao; Lee, Hong-Hsi

2012-05-01

209

Deconfined fractionally charged excitation in any dimensions  

NASA Astrophysics Data System (ADS)

An exact incompressible quantum liquid is constructed at the filling factor 1/m2 in the square lattice. It supports deconfined fractionally charged excitation. At the filling factor 1/m2, the excitation has fractional charge e/m2, where e is the electric charge. This model can be easily generalized to the n-dimensional square lattice (integer lattice), where the charge of excitations becomes e/mn.

Chern, Chyh-Hong; Huang, Po-Hao; Lee, Hong-Hsi

2013-05-01

210

Effect of time profile of laser pulse on the excitation of sound signals in a liquid with a series of laser pulses  

NASA Astrophysics Data System (ADS)

We have studied the sound generation with high repetition rate pulsed laser. We have solved the inhomogeneous wave equation for acoustic pressure in a liquid generated by a laser, using Green’s function formalism and convolution technique. To obtain the maximum pressure of the sound waves, we found the conditions on repetition rate and on period of laser pulse of various shapes. Our analysis shows that the sound generated in a liquid with a series of laser pulses is highly affected by the time profile of the pulses besides other parameters, namely laser beam diameter, laser beam optical wavelength, repetition rate and period of laser pulse. This effect is pronounced particularly in frequency domain. We found that the noise of higher harmonics in the generated sound can be greatly removed with the proper choice of the time profile of the laser pulses. It is found that the pressure is generated around the fundamental frequency for the half-sine and rectangular pulses, with the proper choice of repetition rate and period of pulse. The application of the present analysis for underwater communication is pointed out.

Sayal, V. K.; Yadav, L. L.; Maheshwari, K. P.

2011-04-01

211

Self-trapped excitations in condensed matter physics  

Microsoft Academic Search

The authors discuss a general formulation for self-trapped excitations in condensed matter physics. Previously known aspects include lattice polarons, spin polarons, bubblons, etc. New aspects involve collective excitation self-trapping; solidons in liquid He have been suggested as the correct description for rotons. They emphasise the difference of self-trapped excitations with order parameter fluctuations.

M. Heritier; P. Lederer; G. Montambaux

1980-01-01

212

Nuclear excited xenon flashlamp  

SciTech Connect

The optical emissions of nuclear excited Xenon plasmas were investigated to determine basic parameters important to photolytic pumping of lasers. Gas mixtures of Helium-3 and Xenon were irradiated in the steady state mode in the University of Florida Training Reactor at neutron flux levels of about 10/sup 12//cm/sup 2/.s, generating a power density in the gas of approximately 3 milliwatts/cm/sup 3/. Optical emissions from the gas were primarily due to Xe/sub 2/* band emission at 172 nm with a few Xell lines in the visible and ir. Energy transfer from the /sup 3/He(n,p)T reaction to the Xe/sub 2/* 172 nm band was 67.0% +- 10%. High pressure gas mixtures (4 atm.) of Helium-3 and Xenon were irradiated in the pulse mode (250 ..mu..s FWHM) at the fast burst reactor at the Aberdeen Pulsed Radiation Facility at thermal neutron flux levels of about 10/sup 17//cm/sup 2/.s, generating a power density in the gas of about 1 kilowatt/cm/sup 3/. Optical emissions from the gas extended from the vacuum ultraviolet through the visible to the infrared, resembling a discharge excited lamp with a current density of about 1500 amp./cm/sup 2/. Such a lamp could pump a Neodymium YAG or liquid laser.

Cox, J.D.

1982-01-01

213

Persistent current of Luttinger liquid in one-dimensional ring with weak link: Continuous model studied by configuration interaction and quantum Monte Carlo  

Microsoft Academic Search

We study the persistent current of correlated spinless electrons in a continuous one-dimensional ring with a single weak link. We include correlations by solving the many-body Schrodinger equation for several tens of electrons interacting via the short-ranged pair interaction V(x - x'). We solve this many-body problem by advanced configuration-interaction (CI) and diffusion Monte Carlo (DMC) methods. Our CI and

R. Németh; M. Mosko; R. Krcmár; A. Gendiar; M. Indlekofer; L. Mitas

2009-01-01

214

Shock wave excited liquid micro-jets  

NASA Astrophysics Data System (ADS)

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 100m/s and more. Further the dependencies of the pressure amplitude, capillary diameter, and interface curvature on the jet velocity are presented.

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

2006-11-01

215

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

216

On non-Fermi liquid quantum critical points in heavy fermion metals  

SciTech Connect

Heavy electron metals on the verge of a quantum phase transition to magnetism show a number of unusual non-Fermi liquid properties which are poorly understood. This article discusses in a general way various theoretical aspects of this phase transition with an eye toward understanding the non-Fermi liquid phenomena. We suggest that the non-Fermi liquid quantum critical state may have a sharp Fermi surface with power law quasiparticles but with a volume not set by the usual Luttinger rule. We also discuss the possibility that the electronic structure change associated with the possible Fermi surface reconstruction may diverge at a different time/length scale from that associated with magnetic phenomena.

Senthil, T. [Center for Condensed Matter Theory, Indian Institute of Science, Bangalore 560012 (India) and Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, MA (United States)]. E-mail: senthil@mit.edu

2006-07-15

217

How to Study Correlation Functions in Fluctuating Bose Liquids Using Interference Experiments  

SciTech Connect

Interference experiments with independent condensates provide a powerful tool for analyzing correlation functions. Scaling of the average fringe contrast with the system size is determined by the two-point correlation function and can be used to study the Luttinger liquid liquid behavior in one-dimensional systems and to observe the Kosterlitz-Thouless transition in two-dimensional quasicondensates. Additionally, higher moments of the fringe contrast can be used to determine the higher order correlation functions. In this article we focus on interference experiments with one-dimensional Bose liquids and show that methods of conformal field theory can be applied to calculate the full quantum distribution function of the fringe contrast.

Gritsev, Vladimir; Demler, Eugene [Department of Physics, Harvard University, Cambridge, MA 02138 (United States); Altman, Ehud [Department of Condensed Matter Physics, The Weizmann Institute of Science Rehovot, 76100 (Israel); Polkovnikov, Anatoli [Department of Physics, Boston University, Boston, MA 02215 (United States)

2006-11-07

218

Shear-excited sound in magnetic fluid.  

PubMed

Perceptible sound is shown to be excited in ferrofluids by the shear motion of a rigid plate, if the fluid is exposed to a magnetic field oblique both to the plate and to the direction of propagation. This is in contrast to other fluids, including anisotropic ones such as nematic liquids. PMID:12190607

Müller, Hanns Walter; Liu, Mario

2002-07-22

219

Faraday waves under time-reversed excitation.  

PubMed

Do parametrically driven systems distinguish periodic excitations that are time mirrors of each other? Faraday waves in a Newtonian fluid are studied under excitation with superimposed harmonic wave forms. We demonstrate that the threshold parameters for the stability of the ground state are insensitive to a time inversion of the driving function. This is a peculiarity of some dynamic systems. The Faraday system shares this property with standard electroconvection in nematic liquid crystals [J. Heuer et al., Phys. Rev. E 78, 036218 (2008)]. In general, time inversion of the excitation affects the asymptotic stability of a parametrically driven system, even when it is described by linear ordinary differential equations. Obviously, the observed symmetry has to be attributed to the particular structure of the underlying differential equation system. The pattern selection of the Faraday waves above threshold, on the other hand, discriminates between time-mirrored excitation functions. PMID:23496716

Pietschmann, Dirk; Stannarius, Ralf; Wagner, Christian; John, Thomas

2013-03-01

220

Liquid White Enamel.  

ERIC Educational Resources Information Center

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

Widmar, Marge

1985-01-01

221

Ultraviolet organic liquid lasers  

Microsoft Academic Search

A flashlamp-excited organic liquid laser system capable of stimulated emission down to 340 nm in the ultraviolet has been developed. The flashlamp has a rise time of 50 ns and energy capacity of 20 joules or more. There are several efficient laser compounds that emit below 400 nm, and the most promising appears to be the p-terphenyl laser, which emits

HORACE W. FURUMOTO; HARRY L. CECCON

1970-01-01

222

Mechanical Factors in the Excitation of Clupeid Lateral Lines  

Microsoft Academic Search

The excitation of lateral line sense organs (neuromasts) might be expected to depend on differences of movement between the liquid inside the main lateral line canals (the ones that contain the neuromasts) and the walls of these canals. We have investigated this net movement in relation to events in the water around fish. Liquid displacements inside a given part of

E. J. Denton; John Gray

1983-01-01

223

Absorption and refraction of radiation by liquids. I. Refraction by pure liquids  

Microsoft Academic Search

Expressions for the dielectric constant of a pure liquid are obtained from quantum electrodynamics, and compared with those obtained from electrostatic arguments. The Lorentz cavity field is shown to be associated with off-resonance intermolecular exchange of excitation. An application of perturbation theory up to a level including such excitation exchange leads to the Debye equation for pure non-polar liquids, and

L. A. Dissado

1970-01-01

224

Fermi Liquid Berry Phase Theory of the Anomalous Hall Effect  

NASA Astrophysics Data System (ADS)

Charged Fermi liquids with broken time-reversal symmetry have an intrinsic anomalous Hall effect that derives from the Berry phases accumulated by accelerated quasiparticles that move on the Fermi surface. The intrinsic Hall conductivity is given by a new fundamental geometric Fermi liquid formula that can be regarded as the derivative with respect to magnetic flux density of the Luttinger fomula relating the density of mobile charge carriers to the k-space volume enclosed by the Fermi surface. This formula can be derived by an integration-by-parts of the Karplus-Luttinger free-electron band-structure formula to yield a topological (QHE) part plus a geometrical part expressed completely at the Fermi surface, and which has a natural generalization to interacting Fermi liquid quasiparticles (QP's). The QP Berry phases are properties of the eigenstates of the (exact) single-particle Green's function at the Fermi surface, which is a Hermitian matrix with Bloch-state eigenvectors; the Berry phases derive from the variation on the Fermi surface of the spatially-periodic factor of the QP Bloch state that characterizes how the total QP amplitude is distributed among the different electronic orbitals in the unit cell. In the case of 3D ferromagnetic metals, the Berry phases derive from the interplay of exchange splitting with spin-orbit coupling (both must be present). Remarkably, the new formula also applies to Fermi-liquid analogs such as the 2D composite fermion (CF) fluid in the half-filled lowest Landau level: in this case, the QP is a bound electron+vortex composite and not a Bloch state. This QP structure varies on the CF Fermi surface in a way that exactly gives the expected result xycirc = e^2/2h, unaffected by any Fermi surface anisotropy, thus explaining how a quantized value of xycirc persists even though the CF Fermi liquid is not an incompressible FQHE state. The geometric anomalous Hall effect formula suggests a more intrinsic geometric description of the Fermi surface, where the Fermi vector kF(s) is only one of a number of properties that vary on a curved (D-1)-dimensional Fermi surface manifold parametrized by curvilinear coordinates s; other properties include the Berry curvature field F(s), quasiparticle mean free path l(s),etc. The new formula also naturally takes into account non-trivial (multiply-connected) Fermi surface topology and open orbits.

Haldane, F. D. M.

2006-03-01

225

Excitation Chains at the Glass Transition  

SciTech Connect

The excitation-chain theory of the glass transition, proposed in an earlier publication, predicts diverging, super-Arrhenius relaxation times and, via a similarly diverging length scale, suggests a way of understanding the relations between dynamic and thermodynamic properties of glass-forming liquids. I argue here that critically large excitation chains play a role roughly analogous to that played by critical clusters in the droplet model of vapor condensation. Unlike a first-order condensation point in a vapor, the glass transition is not a conventional phase transformation, and may not be a thermodynamic transition at all.

Langer, J. S. [Department of Physics, University of California, Santa Barbara, California 93106-9530 (United States)

2006-09-15

226

Excitations Propagating Along Surfaces  

Microsoft Academic Search

A number of equations is deduced which describe propagation of excitations along $n$-dimensional surfaces in $R^N$. Usual excitations in wave theory propagate along 1-dimensional trajectories. The role of the medium of propagation of excitations considered in this paper is played by the infinite dimensional space of $(n-1)$-dimensional surfaces in $R^N$. The role of rays is played by $n$-dimensional solution surfaces

A. V. Stoyanovsky

2003-01-01

227

Holographic Quantum Liquid  

SciTech Connect

Quantum liquids are characterized by the distinctive properties such as the low-temperature behavior of heat capacity and the spectrum of low-energy quasiparticle excitations. In particular, at low temperature, Fermi liquids exhibit the zero sound, predicted by Landau in 1957 and subsequently observed in liquid He-3. In this Letter, we ask whether such characteristic behavior is present in theories with a holographically dual description. We consider a class of gauge theories with fundamental matter fields whose holographic dual in the appropriate limit is given in terms of the Dirac-Born-Infeld action in anti-de Sitter space. We find that these systems also exhibit a sound mode at zero temperature despite having a non-Fermi-liquid behavior of the specific heat. These properties suggest that holography identifies a new type of quantum liquid which potentially could be experimentally realized in strongly correlated systems.

Karch, A. [Department of Physics, University of Washington, Seattle, Washington 98195-1560 (United States); Son, D. T. [Institute for Nuclear Theory, University of Washington, Seattle, Washington 98195-1550 (United States); Starinets, A. O. [School of Natural Sciences, Institute for Advanced Study, Einstein Drive, Princeton, New Jersey 08540 (United States); School of Physics and Astronomy, University of Southampton, Highfield, Southampton SO17 1BJ (United Kingdom)

2009-02-06

228

Organic photochemistry: Exciting excited-state aromaticity  

NASA Astrophysics Data System (ADS)

In 1972, Baird published rules describing aromaticity and antiaromaticity in the lowest triplet excited states of annulenes. The fortieth anniversary of Baird's rules -- which are the reverse of Hückel's rules for aromaticity and antiaromaticity in the ground state -- ought to be celebrated before 2012 comes to an end.

Ottosson, Henrik

2012-12-01

229

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

230

Observation of spin and charge collective modes in one-dimensional metallic chains  

Microsoft Academic Search

The many-body theory of interacting electrons in solids establishes the existence of elementary excitations, named quasi-particles, which show a one-to-one correspondence with non-interacting electrons. But this so-called Fermi liquid approach breaks down spectacularly in one-dimensional metals. In this situation, which is described by the Luttinger liquid formalism, the quasiparticles are replaced by distinct collective excitations involving spin and charge, called

P. Segovia; D. Purdie; M. Hengsberger; Y. Baer

1999-01-01

231

Current and charge distributions of the fractional quantum Hall liquids with edges  

NASA Astrophysics Data System (ADS)

An effective Chern-Simons theory for the quantum Hall states with edges is studied by treating the edge and bulk properties in a unified fashion. An exact steady-state solution is obtained for a half-plane geometry using the Winer-Hopf method. For a Hall bar with finite width, it is proved that the charge and current distributions do not have a diverging singularity. It is shown that there exists only a single mode even for the hierarchical states, and the mode is not localized exponentially near the edges. Thus this result differs from the edge picture in which electrons are treated as strictly one-dimensional chiral Luttinger liquids.

Shiraishi, Jun'ichi; Kohmoto, Mahito

1996-12-01

232

Current and charge distributions of the fractional quantum Hall liquids with edges  

NASA Astrophysics Data System (ADS)

An effective Chern-Simons theory for the quantum Hall states with edges is studied by treating the edge and bulk properties in a unified fashion. An exact steady-state solution is obtained for a half-plane geometry using the Winer-Hopf method. For a Hall bar with finite width, it is proved that the charge and current distributions do not have a diverging singularity. It is shown that there exists only a sigle mode even for the hierarchical states, and the mode is not localized exponentially near the edges. Thus our results are not consistent with the edge picture for the fractional quantum Hall effect involving the chiral Luttinger liquids.

Shiraishi, Jun'ichi; Kohmoto, Mahito

1997-03-01

233

Excited Charm States  

SciTech Connect

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

Shukla, S.

1994-12-31

234

Molecular excitation in sprites  

Microsoft Academic Search

We have determined the molecular internal energy distribution in the N2 B³IIg state from the fluorescence measured during the observations of sprites during 1995. Spectrally resolved data from two different instruments and three different sprites are compared with theoretical spectra to obtain excited state vibrational distributions. Energy dependent electron excitation cross-sections and laboratory data were used to estimate the energies

B. D. Green; M. E. Fraser; W. T. Rawlins; L. Jeong; W. A. M. Blumberg; S. B. Mende; G. R. Swenson; D. L. Hampton; E. M. Wescott; D. D. Sentman

1996-01-01

235

Molecular excitation in sprites  

Microsoft Academic Search

We have determined the molecular internal energy distribution in the N2 B3Pig state from the fluorescence measured during the observations of sprites during 1995. Spectrally resolved data from two different instruments and three different sprites are compared with theoretical spectra to obtain excited state vibrational distributions. Energy dependent electron excitation cross-sections and laboratory data were used to estimate the energies

B. D. Green; M. E. Fraser; W. T. Rawlins; L. Jeong; W. A. M. Blumberg; S. B. Mende; G. R. Swenson; D. L. Hampton; E. M. Wescott; D. D. Sentman

1996-01-01

236

Collective excitations on a surface of topological insulator  

PubMed Central

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

2012-01-01

237

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

NASA Astrophysics Data System (ADS)

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

Gweon, Gey-Hong

238

Excitation Methods for Bridge Structures  

SciTech Connect

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

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

1999-02-08

239

Excited upsilon radiative decays  

SciTech Connect

Bottomonium S-wave states were studied using lattice NRQCD. Masses of ground and excited states were calculated using multiexponential fitting to a set of correlation functions constructed using both local and wavefunction-smeared operators. Three-point functions for M1 transitions between vector and pseudoscalar states were computed. Robust signals for transitions involving the first two excited states were obtained. The qualitative features of the transition matrix elements are in agreement with expectations. The calculated values of matrix elements for {Upsilon}(2S) and {Upsilon}(3S) decay are considerably larger than values inferred from measured decay widths.

Lewis, Randy; Woloshyn, R. M. [Department of Physics and Astronomy, York University, Toronto, Ontario, M3J 1P3 (Canada); TRIUMF, 4004 Wesbrook Mall, Vancouver, British Columbia, V6T 2A3 (Canada)

2011-11-01

240

Molecular excitation in sprites  

NASA Astrophysics Data System (ADS)

We have determined the molecular internal energy distribution in the N2 B³IIg state from the fluorescence measured during the observations of sprites during 1995. Spectrally resolved data from two different instruments and three different sprites are compared with theoretical spectra to obtain excited state vibrational distributions. Energy dependent electron excitation cross-sections and laboratory data were used to estimate the energies of electrons producing the red sprite radiance. Implications for chemical production in the mesosphere and critical future measurements are discussed.

Green, B. D.; Fraser, M. E.; Rawlins, W. T.; Jeong, L.; Blumberg, W. A. M.; Mende, S. B.; Swenson, G. R.; Hampton, D. L.; Wescott, E. M.; Sentman, D. D.

241

Gammagard Liquid  

Center for Biologics Evaluation and Research (CBER)

... Liquid For maintenance therapy to improve muscle strength and ... license application for Immune Globulin Infusion (Human) [GAMMAGARD LIQUID ... More results from www.fda.gov/biologicsbloodvaccines/bloodbloodproducts/approvedproducts

242

Soliton excitation in superlattice.  

National Technical Information Service (NTIS)

Excitation of soliton in superlattice has been investigated theoretically. It is noted that the soliton velocity u and the length L depend on the amplitude E(sub 0) and that an increase in the amplitude causes soliton width L to approach zero and the velo...

S. Y. Mensah F. K. A. Allotey N. G. Mensah A. K. Twum

1995-01-01

243

Elephant's foot phenomenon in liquid storage tanks  

Microsoft Academic Search

This paper presents a method for analyzing the seismic response of a flat bottomed cylindrical liquid storage tank to vertical earthquake excitation. Here, vertical earthquake acceleration is considered to correspond to an increase in the density of a stored liquid. Taking into account the vertical and horizontal earthquake loads, hydrostatic pressure, and considering restrictive moment and shear forces at shell-bottom

1983-01-01

244

Axial response of an amphora-type liquid column  

NASA Astrophysics Data System (ADS)

Under axial microgravity, an originally circular cylindrical liquid column assumes an amphora-type geometry. The response of an axially excited amphora-type liquid column consisting of non-viscous liquid has been investigated for a harmonic excitation. Free surface displacement- and velocity-response have been determined. The results shall be used for the efficient planning of the "LICORE" experiments in the second German Spacelab mission (D-2).

Bauer, H. F.; Eidel, W.

245

Particle Emission But Also Fission in the Decay of Very Excited Nuclei.  

National Technical Information Service (NTIS)

An extension of the statistical model for the study of very excited nuclei is presented. The temperature and angular momentum dependences of the fission barriers are obtained in a liquid drop picture. It provides us with the relevant potential landscapes ...

H. Delagrange C. Gregoire Y. Abe N. Carjan

1986-01-01

246

Thermally driven acoustic oscillations, Part VI: Excitation and power  

Microsoft Academic Search

Summary In continuation of previous work in the field of thermally driven acoustic oscillations, the problem of excited oscillations is treated and presented in detail for the Sondhauss tube and for gas-liquid oscillations. The problem of the maximally attainable mechanical power from a Sondhauss tube is discussed.

Ulrich A. Mfiller; Nikolaus Rott

1983-01-01

247

Fluid Excitation Forces Acting on a Tube Array.  

National Technical Information Service (NTIS)

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 arra...

S. S. Chen J. A. Jendrzejczyk

1985-01-01

248

Librational echo: Subpicosecond intermolecular interactions in liquid  

SciTech Connect

The ultrafast optical Kerr effect observed in liquids upon two-pulse laser excitation is studied theoretically. It is shown that a Raman echo on librational frequencies (librational echo) can be excited in liquid. The librational echo has the following features: its shape and amplitude strongly depend on the local inhomogeneity of a medium and the form of local potentials; and the echo signal can be separated into the contributions of the phase and irreversible relaxation of coherent molecular librations. These properties of the librational echo can be used for studying the specific features of the local structure of liquids by the method of selective subpicosecond spectroscopy of molecular librations. (nonlinear optical phenomena)

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

2008-02-28

249

[Laufberger's excitation theory].  

PubMed

The author gives an account of V. Laufberger's Excitation theory at the occasion of the 100th anniversary of his birthday. This work was published as a monograph in 1947 and contains many data which foresee the further development of neuro-sciences and other scientific disciplines. From a certain aspect it is more cybernetic than Wiener's "Cybernetics" published one year later. It applies in a genial way the principle of logical elements made up of binary functional elements, backfeeds, parallel organization of neuron networks, and memories based on so-called spinning excitations. It is the first modern model of cerebral activity. It combines within one system the neuron and psychic level of organization of the brain. PMID:2224962

Radil, T

1990-08-24

250

Trapped and excited  

SciTech Connect

The trapped w modes of stars with a first order phase transition (a density discontinuity) are computed and the excitation of some of the modes of these stars by a perturbing shell is investigated. Attention is restricted to odd parity (''axial'') w modes. With R the radius of the star, M its mass, R{sub i} the radius of the inner core and M{sub I} the mass of such core, it is shown that stars with R/M{ge}5 can have several trapped w modes, as long as R{sub i}/M{sub i}{lt}2.6. Excitation of the least damped w mode is confirmed for a few models. All of these stars can only exist, however, for values of the ratio between the densities of the two phases, greater than {approximately}46. We also show that stars with a phase transition and a given value of R/M can have far more trapped modes than a homogeneous single density star with the same value of R/M, provided both R/M and R{sub i}/M{sub i} are smaller than 3. If the phase transition is very fast, most of the stars with trapped modes are unstable to radial oscillations. We compute the time of instability, and find it to be comparable to the damping of the w mode excited in most cases where w-mode excitation is likely. If on the other hand the phase transition is slow, all the stars are stable to radial oscillations.

Andrade, Zeferino

2001-06-15

251

Excitable scale free networks  

NASA Astrophysics Data System (ADS)

When a simple excitable system is continuously stimulated by a Poissonian external source, the response function (mean activity versus stimulus rate) generally shows a linear saturating shape. This is experimentally verified in some classes of sensory neurons, which accordingly present a small dynamic range (defined as the interval of stimulus intensity which can be appropriately coded by the mean activity of the excitable element), usually about one or two decades only. The brain, on the other hand, can handle a significantly broader range of stimulus intensity, and a collective phenomenon involving the interaction among excitable neurons has been suggested to account for the enhancement of the dynamic range. Since the role of the pattern of such interactions is still unclear, here we investigate the performance of a scale-free (SF) network topology in this dynamic range problem. Specifically, we study the transfer function of disordered SF networks of excitable Greenberg-Hastings cellular automata. We observe that the dynamic range is maximum when the coupling among the elements is critical, corroborating a general reasoning recently proposed. Although the maximum dynamic range yielded by general SF networks is slightly worse than that of random networks, for special SF networks which lack loops the enhancement of the dynamic range can be dramatic, reaching nearly five decades. In order to understand the role of loops on the transfer function we propose a simple model in which the density of loops in the network can be gradually increased, and show that this is accompanied by a gradual decrease of dynamic range.

Copelli, M.; Campos, P. R. A.

2007-04-01

252

Wigner crystallization of single photons in cold Rydberg ensembles.  

PubMed

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

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

2013-09-09

253

Harmonically excited orbital variations  

SciTech Connect

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

Morgan, T.

1985-08-06

254

Saturated Liquid Viscosity and Surface Tension of Alternative Refrigerants  

Microsoft Academic Search

Light scattering by thermally excited capillary waves on liquid surfaces or interfaces can be used for the investigation of viscoelastic properties of fluids. In this work, we carried out the simultaneous determination of the surface tension and the liquid kinematic viscosity of some alternative refrigerants by surface light scattering (SLS) on a gas–liquid interface. The experiments are based on a

A. P. Fröba; S. Will; A. Leipertz

2000-01-01

255

Resonance Pacemakers in Excitable Media  

NASA Astrophysics Data System (ADS)

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

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

2006-06-01

256

PREFACE: Functionalized Liquid Liquid Interfaces  

Microsoft Academic Search

Most natural processes take place at interfaces. For this reason, surface science has been a focal point of modern research. At solid-liquid interfaces one can induce various species to adsorb or react, and thus may study interactions between the substrate and adsorbates, kinetic processes, optical properties, etc. Liquid-liquid interfaces, formed by immiscible liquids such as water and oil, have a

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

2007-01-01

257

U-->? problem for a finite hole concentration: A bosonization approach for the normal-state high-Tc superconductors  

NASA Astrophysics Data System (ADS)

The Hubbard model in the strong coupling limit is considered in two dimensions. A bosonization method based on the extention of the Jordan-Wigner transformation to particles with spin and no double occupancy is introduced. We find that at T=0 a Fermi liquid exists and superconductivity appears. For a finite temperature and finite doping a normal state populated with vortices exists. As a result, we have a normal state with separated charge- and spin-density-wave excitations. Formally those excitations can be described with the help of the Luttinger-liquid representation. In the second part we parametrize the Fermi surface by a set of N points. Around each point we describe the Fermi surface excitations by holons and spinons and find a set of N-coupled Luttinger channels. At T=0 we have space-time tunneling of electric charges which destroys the Luttinger liquid in favor of a Fermi liquid. At T?0 or LT-->? (L is the size of the system) tunneling of electric charges might be prohibited giving rise to gapless excitations. In the last part we consider the case with a commensurate frozen flux in the ground state. As a result we find that the excitations are semions.

Schmeltzer, D.

1993-10-01

258

Composite fermion excitations in fractional quantum Hall systems  

SciTech Connect

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

Quinn, J.J. [Univ. of Tennessee, Knoxville, TN (United States)

1995-04-01

259

Plasmonic excitations in nanostructures  

NASA Astrophysics Data System (ADS)

The prevalent classical model of plasmonic calculations for nano-scale metallic clusters is based on the Mie solution. Which consists of solving Maxwell's equations with the material being represented by a dielectric function on its spatial location. However, such a semi-empirical continuum description necessarily breaks down beyond a certain level of coarseness introduced by atomic length scales. Even the bulk based model used for the dielectric function fails by itself. This limitation of the Mie solution has been established by a quantum mechanical calculation with self-consistent treatment of the dielectric response. In order to understand better the plasmonic excitations at nearly atomic scale, we explored the collective electromagnetic response of atomic chains of various sizes and geometries, and we also computed plasmons in graphene in the presence of an impurity. For the atomic chains, we calculated the plasmonic resonances as a function of the system shape, direction of the external applied field, electron filling and atomic separation. Their frequency, oscillator strength and spatial modulation of the induced charge density were analyzed. It was shown that longitudinal and transverse modes can be controlled in amplitude and frequency by the cluster size. It was also observed an abrupt dependence of the modes on the electronic filling. We also find that changes in atomic spacings have a very different impact on low-energy vs. high-energy modes. And it was seen that changing the position of a single atom in a nanostructure can completely alter its collective dielectric response. This strong sensitivity to small changes is the key to controlling the dielectric properties of atomic scale structures, and it can thus become the gateway to a new generation of quantum devices which effectively utilize quantum physics for new functionalities. For graphene it was shown that impurities induce the formation of nanoscale localized plasmonic excitations in graphene sheets. It was studied the dependence of these excitations on the magnitude and size of the impurity potential and electronic filling. It was shown that the impurity potential and doping can be used to tune the properties of nano-plasmonic excitations, demonstrating that graphene is an inherently plasmonic material. It was found that the chemical potential can be used to turn them on and off, but it does not affect their frequency. While their frequency and amplitude can be tuned by varying the strength of the impurity potential. The method employed for this calculation had not been seen before. In principle the results discussed can be tested experimentally by high-frequency optical probes or STM. These results showed that collective excitations in finite systems have properties different from their bulk correspondents. Since there is not a macroscopic number of electrons in the system, the variation of one single electron causes observable differences. The localized resonant modes are very sensitive to even small variations in the system, for example the position of a single atom. This makes it difficult to establish general rules about the properties of collective excitations in atomic structures. On the other hand it also provides a vast range of possibilities that can be explored for achieving new functionalities.

Muniz, Rodrigo Angelo

260

SHOCK-EXCITED OSCILLATOR  

DOEpatents

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

Creveling, R.

1957-12-17

261

Excite Precision Search  

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.

262

Collective excitations of ? hypernuclei  

NASA Astrophysics Data System (ADS)

We discuss low-lying collective excitations of ? hypernuclei using the self-consistent mean-field approaches. We first discuss the deformation properties of ? hypernuclei in the sd-shell region. Based on the relativistic mean-field (RMF) approach, we show that the oblate deformation for 28Si may disappear when a ? particle is added to this nucleus. We then discuss the rotational excitations of Mg?25 using the three-dimensional potential energy surface in the deformation plane obtained with the Skyrme–Hartree–Fock method. The deformation of Mg?25 is predicted to be slightly reduced due to an addition of a ? particle. We demonstrate that this leads to a reduction of electromagnetic transition probability, B(E2), in the ground state rotational band. We also present an application of random phase approximation (RPA) to hypernuclei, and show that a new dipole mode, which we call a soft dipole ? mode, appears in hypernuclei, which can be interpreted as an oscillation of the ? particle against the core nucleus.

Hagino, K.; Yao, J. M.; Minato, F.; Li, Z. P.; Thi Win, M.

2013-09-01

263

Implantation of atoms into liquid helium for the purpose of impurity spectroscopy  

Microsoft Academic Search

Ca+, Sr+, and Ba+ ions are immersed in liquid He II and neutralized in the liquid subsequently by electrons produced by the ``tip-discharge'' method. Strong recombination light emission serves as detector for the production of these atoms in liquid helium. Laser-excited fluorescence spectroscopy of Ca, Sr and Ba atoms in the liquid can be a tool to study the environment

H. Bauer; M. Beau; A. Bernhardt; B. Friedl; H. J. Reyher

1989-01-01

264

Electron excitations in solids and novel materials  

NASA Astrophysics Data System (ADS)

Several applications of the use of ab initio many-body methods in condensed matter theory are presented. In particular, these methods are used for the study of electronic excitations in various kinds of materials, ranging from bulk to low dimensional systems, and from metals to semiconductors. Two types of electron excitations are considered: quasiparticle excitations and electron-hole excitations. The work is organized in five chapters as follows: (1) The first chapter gives an introduction to the concept of quasiparticle and electron-hole excitations, as well as to the many-body framework underlying the theoretical formalism used in this work. (2) Chapter two presents the calculation of quasiparticle lifetimes in graphite. The inverse lifetime of low energy quasi-electrons shows significant deviations from the quadratic behavior naively expected from Fermi liquid theory. The deviations are explained in terms of the unique features of the band structure of this material. (3) In chapter three, the real and imaginary parts of the quasiparticle self-energy in jellium and crystalline Al are calculated at high electron temperatures. We find a decrease in the electron lifetime and an increase in the valence and conduction band widths as the temperature is increased. Calculation of the spectral function suggests that the quasiparticle concept may still be reasonable at high electron temperatures. (4) Chapter four presents calculations of the quasiparticle spectrum of highly irradiated crystalline GaAs. Our results indicate that the valence-conduction band gap is a sensitive function of the amount of electrons excited above the ground state. However, contrary to previous results, we find that it is not possible to induce a complete band gap closure by purely electronic means. (5) In chapter five we present calculations of the electron-hole interaction effects on the optical spectra of several single-walled carbon nanotubes. We show that the optical spectra of both semiconducting and metallic nanotubes studied exhibits important excitonic effects due to their quasi-one dimensional nature. These large many-electron effects explain the discrepancies between previous theories and experiments.

Spataru, Catalin-Dan

265

Interresonator excitation in selective two-stage pumping  

NASA Astrophysics Data System (ADS)

The method of two-stage pumping (which combines two sources of light) has been combined with intracavity absorption spectroscopy to develop a technique for the elimination of microimpurities from gases. One possible setup of this technique involves the use of a liquid laser for the first stage of pumping; laser frequency scanning is used for the selective elimination of impurities from the gas (which is located inside the cavity), and the particles excited during this process are subsequently removed from the gas by a second light beam. Another variant of two-stage excitation is also discussed.

Barashev, P. P.

1980-09-01

266

Excited-state thermodynamics  

NASA Astrophysics Data System (ADS)

In the last several years, the Casimir energy for a variety of (1 + 1)-dimensional integrable models has been determined from the exact S-matrix. It is shown here how to modify the boundary conditions to project out the lowest-energy state, which enables one to find excited-state energies. This is done by calculating thermodynamic expectation values of operators which generate discrete symmetries. This is demonstrated with a number of perturbed conformal field theories, including the Ising model, the three-state Potts model, Zn parafermions, Toda S-matrices, and massless goldstinos. I would like to thank Ken Intriligator, Tim Klassen, Kolya Reshetikhin and Cumrun Vafa for helpful and interesting conversations. I would also like to thank Michael Lässig for mailing me various papers, and Marcio Martins for providing numerical results which poimted out a mistake in an earlier draft.

Fendley, Paul

1992-05-01

267

Market Liquidity and Funding Liquidity  

Microsoft Academic Search

We provide a model that links an asset's market liquidity - i.e., the ease with which it is traded - and traders' funding liquidity - i.e., the ease with which they can obtain funding. Traders provide market liquidity, and their ability to do so depends on their availability of funding. Conversely, traders' funding, i.e., their capital and the margins they

Markus Brunnermeier; Lasse Pedersen

2007-01-01

268

Axonal excitability revisited.  

PubMed

The original papers of Hodgkin and Huxley (J. Physiol. 116 (1952a) 449, J. Physiol. 116 (1952b) 473, J. Physiol. 116 (1952c) 497, J. Physiol. 117 (1952d) 500) have provided a benchmark in our understanding of cellular excitability. Not surprisingly, their model of the membrane action potential (AP) requires revisions even for the squid giant axon, the preparation for which it was originally formulated. The mechanisms they proposed for the voltage-gated potassium and sodium ion currents, IK, and INa, respectively, have been superceded by more recent formulations that more accurately describe voltage-clamp measurements of these components. Moreover, the current-voltage relation for IK has a non-linear dependence upon driving force that is well described by the Goldman-Hodgkin-Katz (GHK) relation, rather than the linear dependence on driving force found by Hodgkin and Huxley. Furthermore, accumulation of potassium ions in the extracellular space adjacent to the axolemma appears to be significant even during a single AP. This paper describes the influence of these various modifications in their model on the mathematically reconstructed AP. The GHK and K+ accumulation results alter the shape of the AP, whereas the modifications in IK and INa gating have surprisingly little effect. Perhaps the most significant change in their model concerns the amplitude of INa, which they appear to have overestimated by a factor of two. This modification together with the GHK and the K+ accumulation results largely remove the discrepancies between membrane excitability of the squid giant axon and the Hodgkin and Huxley (J. Physiol. 117 (1952d) 500) model previously described (Clay, J. Neurophysiol. 80 (1998) 903). PMID:15561301

Clay, John R

2005-05-01

269

Anomalous Hall effect and the ``quantum geometry'' of the Fermi surface of metals in Fermi liquid theory.  

NASA Astrophysics Data System (ADS)

The ``anomalous Hall effect'' in ferromagnetic metals was recently found to be a previously-unrecognized fundamental Fermi liquid property (FDMH, Phys. Rev. Lett. 96, 203602 (2004)), arising from the Berry curvature of the quasiparticle Bloch state at the Fermi surface, when time-reversal symmetry is broken. This turns out to be a fundamental property of metallic Fermi liquids that survives the ``switching on'' of interactions, protected by Ward identities. The Fermi surface is not just a 2-manifold embedded in k-space, but also a 2-manifold embedded in the Hilbert space describing the periodic factor in the quasiparticle Bloch state. Both embeddings induce geometry: the second embedding not only induces a U(1) or SU(2) gauge (Berry) connection, but also a second Riemannian structure. The new realization that the periodic Bloch factor (plus the spin state) induces an extra ''quantum geometry'' of the Fermi surface points towards a new topological description of Fermi liquid theory. Explicit formulas for the anomalous Hall conductivity, Drude tensor, and other properties of arbitary-shape Fermi surfaces will be reviewed. Separate adiabatic conservation laws are associated with each distinct Fermi surface manifold: this generalizes the separate conservation laws at each Fermi point in 1D Luttinger liquids.

Haldane, F. D. M.

2005-03-01

270

Lowest excited states of ¹³O  

Microsoft Academic Search

An excitation function for resonance elastic scattering of p+¹²N was measured in the center of mass energy range of 0.8-2.7 MeV. Measurements were performed using inverse kinematics and the thick-target techniques. The data were analyzed in the framework of the R-matrix formalism. A definitive spin and parity assignment was possible for the first excited state of ¹³O at an excitation

B. B. Skorodumov; P. Boutachkov; A. Aprahamian; S. Almaraz; J. J. Kolata; L. O. Lamm; M. Quinn; A. Woehr; G. V. Rogachev; V. Z. Goldberg; A. Mukhamedzhanov; H. Amro; F. D. Becchetti; Y. Chen; H. Jiang; S. Brown

2007-01-01

271

Optically excited states in positronium  

SciTech Connect

We report optical excitation of the 1{sup 3}S-2{sup 3}P 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. We found that we could saturate the n=2 level and excite a substantial fraction of n=2 positronium to higher levels. Preliminary spectroscopic measurements were performed on n=14 and n=15 positronium. 14 refs., 7 figs.

Howell, R.H.; Ziock, K.P.; Magnotta, F.; Dermer, C.D.; Failor, R.A. (Lawrence Livermore National Lab., CA (USA)); Jones, K.M. (Williams Coll., Williamstown, MA (USA))

1989-11-03

272

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

PubMed

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

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

2013-04-21

273

Structure and electronic properties of a strong dipolar liquid: Born-Oppenheimer molecular dynamics of liquid hydrogen cyanide  

NASA Astrophysics Data System (ADS)

The structure and electronic properties of liquid hydrogen cyanide (HCN) were investigated by carrying out sequential quantum mechanics/Born-Oppenheimer molecular dynamics. Focus was placed on the analysis of the polarization effects, dynamic polarizability and electronic absorption in liquid HCN. At the low-energy range, the HCN dynamic polarizability in the liquid is slightly increased in comparison with the gas-phase. Application of a 1-body approximation for the calculation of the vertical excitation energies indicates small (0.2˜0.3) blue-shifts of the peak positions in the excitation spectrum of liquid HCN relative to the gas-phase HCN monomer.

Martiniano, Hugo F. M. C.; Costa Cabral, Benedito J.

2013-01-01

274

Investigation of Diffusion of Optical Excitations in Divalent Thulium IONS:STRONTIUM-FLUORIDE.  

NASA Astrophysics Data System (ADS)

The migration of optical excitations of divalent thulium ions at low concentration in strontium fluoride are studied using optical techniques. Two types of excitation are studied. The first type is excitation of the metastable E_{5/2} state of thulium. Upper limits are placed on the diffusion length of this excitation of 8.6 nm at 300^circK and 20 nm at 2^circK for sample concentrations less than.026% Tm^{2+ }. These limits are in agreement with a model in which transport is due to optical magnetic dipole-dipole interactions and results in excitation transport over distances of about the mean separation between ions (3.5 nm) at liquid helium temperatures and no transport of excitation at room temperature. Migration of excitation of the ground state hyperfine sublevels of divalent thulium is studied at low temperature using optical techniques by taking advantage of the magneto -optical activity of these sublevels. A diffusion length of a few microns is predicted for this excitation due to magnetic dipole-dipole interactions between nearest neighbor ion pairs. The excitation is observed to have a diffusion length less than 2 microns, however the size of the laser induced population grating in these sublevels is less than 12% of the value predicted by theory. This indicates rapid relaxation of the spin excitation over short timescales and is believed to be due to spin-lattice relaxation during the time following the laser excitation pulse that the lattice is not at thermal equilibrium.

D'Amato, Francis Xavier

275

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

276

Cavity excitation of coherent hypersound  

Microsoft Academic Search

In this paper, we analyze the generation of hypersonic waves via piezoelectric surface excitation in cavity resonators and derive formulas enabling one to calculate the electromechanical conversion factor and the electric field direction for optimal excitation of any pure acoustic mode, provided the relevant material constants and cavity parameters are known. Quantitative results are given for certain acoustic modes in

D. Soumpasis

1973-01-01

277

Fission Fragment Excited Laser System.  

National Technical Information Service (NTIS)

A laser system and method for exciting lasing action in a molecular gas lasing medium includes cooling the lasing medium to a temperature below about 150 K and injecting fission fragments through the lasing medium so as to preferentially excite low lying ...

D. A. McArthur P. B. Tollefsrud

1976-01-01

278

Microscopic studies of collective spectra of quantum liquid clusters  

Microsoft Academic Search

Theoretical methods are developed for determining the collective vibrational excitation spectra of quantum clusters, and applied to clusters of 4He. A quantum liquid drop model gives excitation energies in terms of two-point ground state density correlations, which are evaluated from microscopic calculations of the ground state wave functions. An alternative approach based on a Bijl–Feynman ansatz for the excited states

M. V. Rama Krishna; K. B. Whaley

1990-01-01

279

Coulomb excitation of 31Mg  

NASA Astrophysics Data System (ADS)

The ground state properties of 31Mg indicate a change of nuclear shape at N=19 with a deformed J?=1/2+ intruder state as a ground state, implying that 31Mg is part of the "island of inversion". The collective properties of excited states were the subject of a Coulomb excitation experiment at REX-ISOLDE, CERN, employing a radioactive 31Mg beam. De-excitation ?-rays were detected by the MINIBALL ?-spectrometer in coincidence with scattered particles in a segmented Si-detector. The level scheme of 31Mg was extended. Spin and parity assignment of the 945 keV state yielded 5/2+ and its de-excitation is dominated by a strong collective M1 transition. Comparison of the transition probabilities of 30,31,32Mg establishes that for the N=19 magnesium isotope not only the ground state but also excited states are largely dominated by a deformed pf intruder configuration.

Seidlitz, M.; Mücher, D.; Reiter, P.; Bildstein, V.; Blazhev, A.; Bree, N.; Bruyneel, B.; Cederkäll, J.; Clement, E.; Davinson, T.; van Duppen, P.; Ekström, A.; Finke, F.; Fraile, L. M.; Geibel, K.; Gernhäuser, R.; Hess, H.; Holler, A.; Huyse, M.; Ivanov, O.; Jolie, J.; Kalkühler, M.; Kotthaus, T.; Krücken, R.; Lutter, R.; Piselli, E.; Scheit, H.; Stefanescu, I.; van de Walle, J.; Voulot, D.; Warr, N.; Wenander, F.; Wiens, A.

2011-06-01

280

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

281

Market Liquidity and Funding Liquidity  

Microsoft Academic Search

We provide a model that links an asset's market liquidity (i.e., the ease with which it is traded) and traders' funding liquidity (i.e., the ease with which they can obtain funding). Traders provide market liquidity, and their ability to do so depends on their availability of funding. Conversely, traders' funding, i.e., their capital and margin requirements, depends on the assets'

Markus K. Brunnermeier; Lasse Heje Pedersen

2009-01-01

282

Mystery Liquids  

NSDL National Science Digital Library

In this math lesson, learners analyze the density of liquids in order to explore linear functions. Learners gather mass and volume data for two mystery liquids, oil and water, and then use the data to explore linear functions. Learners discuss the physical meaning of the slopes and y-intercepts of the various lines they create from scatterplots.

Pbs

2012-01-01

283

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.

284

Vibrational Excitation in Molecular Collisions  

NASA Astrophysics Data System (ADS)

The collision energy dependence of the total cross sections for state resolved translation to vibration energy transfer was measured for several neutral systems. Measurements were made for vibrationally inelastic collisions of iodine with helium, neon, and hydrogen isotopes, as well as collisions of aniline and paradifluorobenzene with helium, all in the thermal energy range. Our new experimental technique uses pulsed supersonic molecular beams for initial state selection, crossed at a variable intersection angle for kinematic, continuously tunable collision energy selection. The scattered products are state-selectively detected in the intersection region by laser induced fluoroscence. The iodine cross section energy dependences are approximately linear, quadratic, and cubic for v = 0 to 1, 2, and 3 excitations respectively, as expected from a classical-quantal correspondence principle model. Extreme mode specificity was observed in the polyatoms as only 3 of about 20 energetically accessible vibrations were observed to be collisionally excited. In aniline, the 2 lowest frequency modes were excited. The cross section for single quantum excitations of the inversion mode of the amine group is a strongly decreasing function over the 20 to 250 meV collision energy range. The other observed mode, an out-of-plane bend of the amine group shows a linear onset at threshold for single quantum excitations. The only vibration excited in paradifluorobenzene was the lowest frequency, out-of-plane fluorine bend. Excitation of 1 and 2 quanta was observed. The cross sections both have approximately linear onset at threshold.

Hall, Gregory

285

Liquid Ventilation  

PubMed Central

Mammals have lungs to breathe air and they have no gills to breath liquids. When the surface tension at the air-liquid interface of the lung increases, as in acute lung injury, scientists started to think about filling the lung with fluid instead of air to reduce the surface tension and facilitate ventilation. Liquid ventilation (LV) is a technique of mechanical ventilation in which the lungs are insufflated with an oxygenated perfluorochemical liquid rather than an oxygen-containing gas mixture. The use of perfluorochemicals, rather than nitrogen, as the inert carrier of oxygen and carbon dioxide offers a number of theoretical advantages for the treatment of acute lung injury. In addition, there are non-respiratory applications with expanding potential including pulmonary drug delivery and radiographic imaging. The potential for multiple clinical applications for liquid-assisted ventilation will be clarified and optimized in future.

Tawfic, Qutaiba A.; Kausalya, Rajini

2011-01-01

286

Fractionalization of itinerant anyons in one-dimensional chains.  

PubMed

We construct models of interacting itinerant non-Abelian anyons moving along one-dimensional chains, focusing, in particular, on itinerant Ising anyon chains, and derive effective anyonic t-J models for the low-energy sectors. Solving these models by exact diagonalization, we find a fractionalization of the anyons into charge and (non-Abelian) anyonic degrees of freedom--a generalization of spin-charge separation of electrons which occurs in Luttinger liquids. A detailed description of the excitation spectrum by combining spectra for charge and anyonic sectors requires a subtle coupling between charge and anyonic excitations at the microscopic level (which we also find to be present in Luttinger liquids), despite the macroscopic fractionalization. PMID:23003180

Poilblanc, Didier; Troyer, Matthias; Ardonne, Eddy; Bonderson, Parsa

2012-05-14

287

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

288

The Biophysical Basis of Excitability  

NASA Astrophysics Data System (ADS)

Defines the basic concepts from biology, mathematics, physics and chemistry that are needed to understand how excitable cells function. Applies them specifically to the study of membrane transport, artificial membranes, signal capturing and analysis in biological systems.

Ferreira, H. G.; Marshall, M. W.

289

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

290

The liquid state of large clusters with pairwise atomic interactions  

Microsoft Academic Search

Formation of the liquid state for clusters with a pair interaction between atoms is examined within the framework of the void model, in which configurational excitation of atoms results from formation of voids. Void parameters are found from computer simulation by molecular dynamics methods for Lennard-Jones clusters and from real thermodynamic parameters of the liquid states of condensed inert gases.

R. S. Berry; B. M. Smirnov

2005-01-01

291

Brain Ischemia and Neuronal Excitability  

Microsoft Academic Search

\\u000a Selective neuronal death in certain brain regions has long been recognized as a consequence of transient cerebral ischemia;\\u000a however, its mechanisms remain unclear. Growing evidence indicates that an increase in neuronal excitability may contribute\\u000a to this process. Both excitatory synaptic inputs and voltage-dependent potassium currents are important for regulating neuronal\\u000a excitability. Recent studies demonstrate that the activities of excitatory synaptic

Ping Deng; Zao C. Xu

292

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

293

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

294

Oscillation Modes of Nematic Liquid Crystals  

Microsoft Academic Search

A novel self-contained two-dimensional contiuum theory for thin nematic liquid crystal layers has been developed. The theory, which is quasistatic in nature, predicts spatially varying oscillations of the molecular axes in modal striated patterns in response to an ac electric field. An oscillation threshold voltage is derived which increases with increased frequency of excitation. Also, the theory predicts that the

G. H. Conners; K. B. Paxton

1972-01-01

295

Picosecond study of electronically excited singlet states of nucleic acid components  

NASA Astrophysics Data System (ADS)

The method of picosecond kinetic Spectroscopy has been used to measure some characteristics of excited singlet states of nucleic acid components in liquid aqueous solutions. It has been shown that the times ?1 or non-radiative relaxation of the excited electronic stale S1 to the ground state S0 for uracil, uridine and thymine lie in the range 4 ± 2 ps, while for adenine and cytosine ?1 XXX 4 ps.

Oraevsky, A. A.; Sharkov, A. V.; Nikogosyan, D. N.

1981-10-01

296

Simplex Z2 spin liquids on the kagome lattice with projected entangled pair states: Spinon and vison coherence lengths, topological entropy, and gapless edge modes  

NASA Astrophysics Data System (ADS)

Gapped Z2 spin liquids have been proposed as candidates for the ground state of the S=1/2 quantum antiferromagnet on the kagome lattice. We extend the use of projected entangled pair states to construct (on the cylinder) resonating valence bond (RVB) states including both nearest-neighbor and next-nearest-neighbor singlet bonds. Our ansatz—dubbed “simplex spin liquid”—allows for an asymmetry between the two types of triangles (of order 2%-3% in the energy density after optimization) leading to the breaking of inversion symmetry. We show that the topological Z2 structure is still preserved and, by considering the presence or the absence of spinon and vison lines along an infinite cylinder, we explicitly construct four orthogonal RVB minimally entangled states. The spinon and vison coherence lengths are extracted from a finite size scaling with regard to the cylinder perimeter of the energy splittings of the four sectors and are found to be of the order of the lattice spacing. The entanglement spectrum of a partitioned (infinite) cylinder is found to be gapless, suggesting the occurrence, on a cylinder with real open boundaries, of gapless edge modes formally similar to Luttinger liquid (nonchiral) spin and charge modes. When inversion symmetry is spontaneously broken, the RVB spin liquid exhibits an extra Ising degeneracy, which might have been observed in recent exact diagonalization studies.

Poilblanc, Didier; Schuch, Norbert

2013-04-01

297

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

298

About liquids  

NASA Astrophysics Data System (ADS)

On the basis of a simplified depiction of liquids, solids, and gases, a qualitative discussion is presented of certain properties of liquids with spherically symmetric atoms: their melting and boiling heats and the corresponding temperatures, their coefficients of viscosity and self-diffusion. Results are compared with data for neon, argon, sodium, aluminum, copper, silver, and mercury. Water is also included for order-of-magnitude comparison, although its molecules are not spherically symmetric and internal degrees of freedom cannot be neglected.

Bernstein, Herbert J.; Weisskopf, Victor F.

1987-11-01

299

High-frequency collective excitations in molten and glassy Te studied by inelastic neutron scattering  

SciTech Connect

The spectra of collective excitations of liquid and glassy tellurium have been studied by means of inelastic neutron scattering. Here we report on the dynamics of liquid Te as measured at two different temperatures, just above melting (T{sub m}=723 K) and at {approx}1000 K as well as the glass that is studied at room temperature. Estimates for the velocity of propagating excitations for both temperatures have been obtained from the experimental data, and a contrasting behavior is found with respect to anomalies shown by the adiabatic sound velocity measured by ultrasound methods. The origin of such differences is finally discussed.

Ruiz-Martin, M. D.; Jimenez-Ruiz, M. [Institut Laue Langevin, 6 Rue Jules Horowitz, BP. 156, F-38042 Grenoble Cedex 9 (France); Bermejo, F. J. [C.S.I.C., Department of Electricity and Electronics, UPV/EHU, Box 644, 4880 Bilbao (Spain); Fernandez-Perea, R. [Instituto de Estructura de la Materia, Consejo Superior de Investigacioens Cientifcas, Serrano 123, E-28006 Madrid (Spain)

2006-03-01

300

Threshold excitation of photoabsorption convection  

Microsoft Academic Search

The article considers questions of the stability of the equilibrium states of a liquid which absorbs light. Threshold values are found for the intensity of the light in the problem of the stability of the equilibrium of a liquid in a square cavity with three thermally insulated walls. A steady-state integro-interpolation scheme is presented for the numerical calculation of problems

B. M. Berkovskii; L. P. Ivanov

1971-01-01

301

Measurement of acoustic properties of liquid using liquid flow SH-SAW sensor system  

Microsoft Academic Search

The SH-SAW resonator having narrow bandwidth and higher Q value has been used for sensing the properties in ionic and viscosity of liquid. The surface acoustic waves with the shear horizontal displacement (SH-SAW) are excited on a piezoelectric substrate; 36 rotated Y cut X prop. LiTaO3 (36 YX LiTaO3) and the liquid flow sensing system was constructed by using two-port

T Nomura; A Saitoh; Y Horikoshi

2001-01-01

302

Resonance Raman spectroscopy utilizing tunable deep ultraviolet excitation for materials characterization  

NASA Astrophysics Data System (ADS)

Resonance Raman spectroscopy offers some key benefits over other spectroscopy methods. In one facet, resonance Raman provides a level of specificity not present in non-resonant Raman scattering. In another facet, resonance Raman can provide increased scattering cross-sections that rival those associated with the intensities of species fluorescence. These features provide mechanisms for improved trace species detection in current Raman remote sensing applications; as well as signal level enhancement in tiny volume regimes, such as those typical in near-field optical microscopy. This dissertation presents three main thrusts that are not well documented in the previous resonance Raman studies. We demonstrate fine resolution (approx 0:1nm) resonance tuning of the excitation wavelength corresponding to sharp absorption bands in liquid benzene and liquid toluene. The Raman spectra for these materials show an appreciable increase in scattering intensity of fundamental vibrational modes and show significant enhancements in scattering intensities for overtone and combination vibrational modes not observed with non-resonant excitation. Resonantly excited fundamental modes are observed to be enhanced by 3 to 5 orders of magnitude over non-resonant excitation; and several resonantly excited overtone modes are observed for both liquid benzene and liquid toluene. We have observed, that for liquid benzene and liquid toluene, the maximum Raman scattering intensity is realized when the excitation wavelength corresponds to that of the vapor phase absorption maximum, not the liquid phase absorption maximum as expected. We present a simple model of the time-dependent energy accumulation in the scattering volume that suggests that the scattering medium is a highly disorganized fluid. The observed Raman scattering intensity originates from this metastable fluid observed during the liquid-vapor phase transition. Using different concentration solutions of liquid benzene in heptane, we illustrate the influence species absorption has on the potential level of signal enhancement offered by resonance Raman scattering. In low concentration environments, resonance Raman signal levels can be 1 to 3 orders of magnitude larger than those of non-resonant Raman. As concentration increases, the signal levels of both resonant and non-resonant Raman become comparable. Using the species absorption to normalize the number of scattering molecules, the resonance enhancement is shown to be 3 to 5 orders of magnitude over the non-resonant excitation.

Chadwick, Christopher Todd

303

Electrochemically induced actuation of liquid metal marbles.  

PubMed

Controlled actuation of soft objects with functional surfaces in aqueous environments presents opportunities for liquid phase electronics, novel assembled super-structures and unusual mechanical properties. We show the extraordinary electrochemically induced actuation of liquid metal droplets coated with nanoparticles, so-called "liquid metal marbles". We demonstrate that nanoparticle coatings of these marbles offer an extra dimension for affecting the bipolar electrochemically induced actuation. The nanoparticles can readily migrate along the surface of liquid metals, upon the application of electric fields, altering the capacitive behaviour and surface tension in a highly asymmetric fashion. Surprising actuation behaviours are observed illustrating that nanoparticle coatings can have a strong effect on the movement of these marbles. This significant novel phenomenon, combined with unique properties of liquid metal marbles, represents an exciting platform for enabling diverse applications that cannot be achieved using rigid metal beads. PMID:23708728

Tang, Shi-Yang; Sivan, Vijay; Khoshmanesh, Khashayar; O'Mullane, Anthony P; Tang, Xinke; Gol, Berrak; Eshtiaghi, Nicky; Lieder, Felix; Petersen, Phred; Mitchell, Arnan; Kalantar-zadeh, Kourosh

2013-05-24

304

Liquid Crystals  

NASA Astrophysics Data System (ADS)

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

1990-01-01

305

Liquid marbles.  

PubMed

The transport of a small amount of liquid on a solid is not a simple process, owing to the nature of the contact between the two phases. Setting a liquid droplet in motion requires non-negligible forces (because the contact-angle hysteresis generates a force opposing the motion), and often results in the deposition of liquid behind the drop. Different methods of levitation-electrostatic, electromagnetic, acoustic, or even simpler aerodynamic techniques-have been proposed to avoid this wetting problem, but all have proved to be rather cumbersome. Here we propose a simple alternative, which consists of encapsulating an aqueous liquid droplet with a hydrophobic powder. The resulting 'liquid marbles' are found to behave like a soft solid, and show dramatically reduced adhesion to a solid surface. As a result, motion can be generated using gravitational, electrical and magnetic fields. Moreover, because the viscous friction associated with motion is very small, we can achieve quick displacements of the droplets without any leaks. All of these features are of potential benefit in microfluidic applications, and also permit the study of a drop in a non-wetting situation-an issue of renewed interest following the recent achievement of super-hydrophobic substrates. PMID:11418851

Aussillous, P; Quéré, D

2001-06-21

306

Nonlinear excitation of plasma convection  

NASA Astrophysics Data System (ADS)

The parametric excitation processes of the zero-frequency modes are considered. Cheng and Okuda (1977, 1978) have found that the rapid generation of convective cells is associated with drift-wave turbulence in an inhomogeneous magnetized plasma. The present investigation is concerned with an analysis of the process of parametric excitation of electrostatic cells by drift waves, taking into account also the excitation of magnetostatic modes by kinetic Alfven waves. The linear properties of the low-frequency modes are considered, giving attention to the convective cell mode and the magnetostatic mode. Relations to perpendicular diffusion are explored. Equilibrium convective cell fluctuations are investigated along with equilibrium magnetostatic fluctuations, and an estimate of cross-field diffusion is obtained. A study is conducted of the magnetostatic modes and the nonlinear stages of the convective cells, taking into consideration the coupling.

Spatschek, K. H.; Laedke, E. W.; Shukla, P. K.; Yu, M. Y.

307

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

308

Effect of loading a plate with different liquids on the propagation of lamb-like waves studied by laser ultrasonics  

Microsoft Academic Search

Three experimental laser ultrasonic configurations-line excitation with scanning detection, grating excitation with single point detection, and grating excitation with scanning probe beam- are shown to consistently reveal the modified propagation properties of Lamb waves on a polyethylene terephthalate (PET) film that is in contact with different liquids on its two sides. Theoretical predictions concerning the physical nature of different wave

Xiaodong Xu; Jozefien Goossens; Gennady Shkerdin; Christ Glorieux

2008-01-01

309

Generator over excitation capability and excitation system limiters  

Microsoft Academic Search

Sometimes, power system events have shown the need for generators to operate in the overexcited region to support stable operation. Operation up to, and transiently beyond, the overexcited limits from the capability curve is sometimes required. The two main issues in the paper are the generator capability in this region and the design of OEL (overexcitation limiters) in the excitation

A. Murdoch; G. E. Boukarim; B. E. Gott; M. J. D'Antonio; R. A. Lawson

2001-01-01

310

Autoresonant Excitation of Antiproton Plasmas  

SciTech Connect

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

Andresen, G. B.; Bowe, P. D.; Hangst, J. S. [Department of Physics and Astronomy, Aarhus University, DK-8000 Aarhus C (Denmark); Ashkezari, M. D.; Hayden, M. E. [Department of Physics, Simon Fraser University, Burnaby British Columbia, V5A 1S6 (Canada); Baquero-Ruiz, M.; Chapman, S.; Fajans, J.; Povilus, A.; So, C. [Department of Physics, University of California at Berkeley, Berkeley, California 94720-7300 (United States); Bertsche, W.; Butler, E.; Charlton, M.; Humphries, A. J.; Madsen, N.; Werf, D. P. van der [Department of Physics, Swansea University, Swansea SA2 8PP (United Kingdom); Carpenter, P. T.; Hurt, J. L.; Robicheaux, F. [Department of Physics, Auburn University, Auburn, Alabama 36849-5311 (United States); Cesar, C. L. [Instituto de Fisica, Universidade Federal do Rio de Janeiro, Rio de Janeiro 21941-972 (Brazil)

2011-01-14

311

Core excitations in exotic nuclei  

NASA Astrophysics Data System (ADS)

The role of core excitations in exotic nuclei is discussed in the framework of a microscopic cluster model. This cluster approach is complemented by the R-matrix theory to take account of the long-range part of the wave functions. We briefly describe the model, and present two recent examples: the neutron-rich nucleus 16B, described by a 15B+n structure, and the proton-rich nucleus 17Na, described by a 16Ne+p structure. In both cases core excitations are shown to play an important role.

Descouvemont, Pierre; Dufour, Marianne; Timofeyuk, Natalia

2013-04-01

312

Macromolecular liquids  

SciTech Connect

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

Safinya, C.R.; Safran, S.A. (Exxon Research and Engineering Co., Annandale, NJ (US)); Pincus, P.A. (Univ. of California at Santa Barbara, Santa Barbara, CA (US))

1990-01-01

313

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

NASA Astrophysics Data System (ADS)

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

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

2013-03-01

314

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.Fåk, A.R. Sakhel, H.R. Glyde, and W.G. Stirling, to be published.) UK. The range of the wavevector Q beyond the roton (Q > 2.0Åis 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 Nozières.(J. Gavoret and Nozières, 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

315

Fluorescence Excitation of Single Molecules.  

National Technical Information Service (NTIS)

A few years ago, many people would have deemed the optical observation of single molecules nearly impossible. Yet, new experiments at room and at liquid helium temperatures have started to remove this psychological barrier. Several applications to trace d...

M. Orrit J. Bernard

1992-01-01

316

Spectrum of a Magnetized Strong-Leg Quantum Spin Ladder  

NASA Astrophysics Data System (ADS)

Inelastic neutron scattering is used to measure the spin excitation spectrum of the Heisenberg S=1/2 ladder material (C7H10N)2CuBr4 in its entirety, both in the gapped spin liquid and the magnetic field-induced Tomonaga-Luttinger spin liquid regimes. A fundamental change of the spin dynamics is observed between these two regimes. Density matrix renormalization group calculations quantitatively reproduce and help understand the observed commensurate and incommensurate excitations. The results validate long-standing quantum field-theoretical predictions but also test the limits of that approach.

Schmidiger, D.; Bouillot, P.; Guidi, T.; Bewley, R.; Kollath, C.; Giamarchi, T.; Zheludev, A.

2013-09-01

317

Fast excitation variable period wiggler  

NASA Astrophysics Data System (ADS)

The design of an easily stackable, variable period length, fast excitation driven wiggler, making use of geometrically alternating substacks of Vanadium Permandur ferromagnetic laminations, interspaced with conductive, non magnetic, laminations which act as eddy current induced 'field reflectors', is discussed and experimental results obtained with short wiggler models are presented.

Vansteenbergen, A.; Gallardo, J.; Romano, T.; Woodle, M.

1991-05-01

318

Launch Excitement with Water Rockets  

ERIC Educational Resources Information Center

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

Sanchez, Juan Carlos; Penick, John

2007-01-01

319

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

320

Photoacoustic generation using coded excitation  

NASA Astrophysics Data System (ADS)

Photoacoustic (PA) imaging has been used to image soft tissue due to its high contrast and high spatial resolution. The generation of PA signal is based on the object's absorption characteristic to the emitted electromagnetic energy. Typically, a Q-switched Nd:YAG laser providing mJ pulse energy is suitable for biomedical PA applications. However, such laser is relatively bulky and expensive. An alternative way is to use a diode laser. A diode laser can generate laser pulse at much higher pulse repetition frequency (PRF). However, the output power of the diode laser is too low for effective PA generation. One method to overcome this problem is to increase the transmission energy using coded excitation. The coded laser signals can be transmitted by a diode laser with high PRF and the signal intensity of the received signal can be enhanced using pulse compression. In this study, we proposed a chirp coded excitation algorithm for a diode laser. Compared to Golay coded excitation seen in the literature, the proposed chirp coded excitation requires only a single transmission. Chirp-coded PA signal was generated by tuning the pulse duration of individual laser pulses in time domain. Result shows that the PA signal intensity can be enhanced after matched filtering. However, high range side-lobes are still present. The compression filter is an important tool to reduce the range side-lobes, which is subject to further investigation.

Su, Shin-Yuan; Li, Pai-Chi

2011-02-01

321

Coulomb Excitation of 231Pa  

Microsoft Academic Search

The nucleus 231Pa was studied by Coulomb-excitation. New states were identified by particle-gamma gamma coincidences using the NORDBALL array in coincidence with two different particle detector systems. A regular band-structure is observed in the 3\\/2[651] band for levels above 9\\/2+ fed by strong E1 transitions from the ground-state band.

M. Wuerkner; J. de Boer; J. Choinski; T. Czosnyka; C. Guenther; J. Iwanicki; M. Kisielinski; A. Kordyasz; M. Kowalczyk; H. Kusakari; J. Kvasil; A. I. Levon; M. Loewe; P. J. Napiorkowski; T. Shizuma; G. Sletten; J. Srebrny; M. Sugawara; T. Weber; Y. Yoshizawa

1999-01-01

322

Multi-photon excitation microscopy  

Microsoft Academic Search

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

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

2006-01-01

323

Pseudorandom selective excitation in NMR.  

PubMed

In this work, average Hamiltonian theory is used to study selective excitation under a series of small flip-angle ?-pulses [???/3] applied either periodically [corresponding to the DANTE pulse sequence] or aperiodically to a spin-1/2 system. First, an average Hamiltonian description of the DANTE pulse sequence is developed that is valid for frequencies either at or very far from integer multiples of 1?, where ? is the interpulse delay. For aperiodic excitation, a single resonance, ?sel, can be selectively excited if the ?-pulse phases are modulated in concert with the interpulse delays. The conditions where average Hamiltonian theory can be accurately applied to describe the dynamics under aperiodic selective pulses, which are referred to as pseudorandom-DANTE or p-DANTE sequences, are similar to those found for the DANTE sequence. Signal averaging over different p-DANTE sequences improves the apparent selectivity at ?sel by reducing the excitations at other frequencies. Experimental demonstrations of p-DANTE sequences and comparisons with the theory are presented. PMID:21795083

Walls, Jamie D; Coomes, Alexandra

2011-07-07

324

Dipole Excited Unidirectionally Conducting Sphere.  

National Technical Information Service (NTIS)

The problem of frequency independent antennas has aroused the interest of many authors in recent years. In this work an attempt is made to solve the problem of a unidirectionally conducting sphere excited by a radial point source. As it is well known, a u...

A. Ishimaru M. A. Gonzalez

1964-01-01

325

Excitation Energy and Well Depth of Superdeformed ^195Pb  

NASA Astrophysics Data System (ADS)

Superdeformed structures are a result of large microscopic shell corrections to the liquid drop formula at large deformations. Excitation energy and well depth are quantities which can be extracted from the study of the decay of SD excitations and can be used to test microscopic predictions. Gammasphere with 95 Compton-suppressed Ge detectors was used to study the population and decay of the four known SD bands in ^195Pb (L. P. Farris et al.), Phys. Rev. C 51, R2288 (1994)via the ^174Yb(^26Mg,5n) reaction. The well depth associated with the SD minimum of ^195Pb was extracted using the model of Stafford and Barrett (C. A. Stafford, B. R. Barrett, Phys. Rev. C 60), 051305 (1999).

Johnson, M. S.; Cizewski, J. A.; Ding, K. Y.; Fotiades, N.; Smith, M. B.; Thomas, J. S.; Becker, J. A.; Bernstein, L. A.; Hauschild, K.; McNabb, D. P.; Clark, R. M.; Deleplanque, M. A.; Diamond, R. M.; Fallon, P.; Lee, I. Y.; Macchiavelli, A. O.; Stephens, F. S.

2003-10-01

326

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

327

Liquid Ammonia  

Microsoft Academic Search

This is a review of the use of liquid ammonia as a solvent for chemical processes. Among the subjects covered are the physical properties of the solvent that defines it as “water like.” The physical and chemical processes associated with the formation of solutions and the properties of those solutions are also convered. Included is a discussion of metal?ammonia solutions,

J. J. Lagowski

2007-01-01

328

Liquid Markets  

Microsoft Academic Search

In terms of both geography and application the liquid filtration market is ubiquitous. Economic upheaval, such as presently experienced in Asia, has less effect on sales than is the case for most products and services. Nevertheless a long and substantial economic crisis in the region will noticeably impact the sales of both equipment and media.

Robert W. Mcllvaine

1998-01-01

329

Physics of the pion liquid  

SciTech Connect

Excited hadronic matter in the temperature interval T = 100--200 MeV is not an ideal pion gas, but rather a liquid, in which attractive interaction among particles plays an important role. Pion dispersion curve is in this case essentially modified by a kind of collective momentum-dependent potential, which becomes important as the quasipion'' comes to the boundary of the system. We show that effects can provide and explanation for a number of recent experimental puzzles, in particular, for the observed copious production of soft pions and soft photons in high energy hadronic reactions. 31 refs., 13 figs.

Shuryak, E.V.

1990-04-01

330

BRIEF COMMUNICATIONS: Raman laser as an efficient source for the excitation of stimulated Raman scattering spectra  

Microsoft Academic Search

Raman lasers with liquid carbon disulfide, nitromethane, benzene, and nitrobenzene active media were used to excite stimulated Raman spectra in crystalline transparent and absorbing matrices. The high efficiency of these lasers in this application was noted and a qualitative physical interpretation of the observed phenomena was developed. Bibtex entry for this abstract Preferred format for this abstract (see Preferences) Find

Yakov S. Bobovich; A. V. Bortkevich; V. I. Petrov

1978-01-01

331

Singular perturbation theory of traveling waves in excitable media (a review)  

Microsoft Academic Search

Waves of chemical or electrical activity, traveling through space, have been observed in several contexts: chemical reaction mixtures in non-convecting liquid phase, cell suspensions, nerve axons, and neuromuscular tissues. Typically, wave-supporting preparations are excitable; that is, they respond and sensitivity to perturbations are rapidly damped out, but suprathreshold disturbances trigger an abrupt and substantial response. The abruptness of the response

John J. Tyson; James P. Keener

1988-01-01

332

Experimental and numerical study of transient condensation of lithium fluoride excited vapors for IFE systems  

Microsoft Academic Search

This paper presents the study of transient cooling and condensation of the non toxic component of flibe, lithium fluoride. The work is part of the effort to provide an experimental feasibility assessment of the application of thick liquid blankets to inertial fusion energy systems. The excited vapors are generated by ablation of about 0.3 grams of a solid sleeve in

P. Calderoni; A. Ying; M. A. Abdou

2003-01-01

333

Collective hypersonic excitations in strongly multiple scattering colloids.  

PubMed

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

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

2011-04-29

334

Excitations in a Four-Leg Antiferromagnetic Heisenberg Spin Tube  

SciTech Connect

Inelastic neutron scattering is used to investigate magnetic excitations in the quasi-one-dimensional quantum spin-liquid system Cu2Cl4 D8C4SO2. Contrary to previously conjectured models that relied on bond-alternating nearest-neighbor interactions in the spin chains, the dominant interactions are actually next-nearest-neighbor in-chain antiferromagnetic couplings. The appropriate Heisenberg Hamiltonian is equivalent to that of a S 1=2 4-leg spin-tube with almost perfect one dimensionality and no bond alternation. A partial geometric frustration of rung interactions induces a small incommensurability of short-range spin correlations.

Garlea, Vasile O [ORNL; Zheludev, Andrey I [ORNL; Regnault, L.-P. [CEA, Grenoble, France; Chung, J.-H. [National Institute of Standards and Technology (NIST); Qiu, Y. [National Institute of Standards and Technology (NIST); Boehm, Martin [Institut Laue-Langevin (ILL); Habicht, Klaus [Hahn-Meitner Institut, Berlin, Germany; Meissner, Michael [Hahn-Meitner Institut, Berlin, Germany; Fernandez-Baca, Jaime A [ORNL

2008-01-01

335

Liquid filtration  

SciTech Connect

Liquid filtration is a fundamental unit operation practiced extensively throughout the chemical process, petroleum, and allied industries. This book is a state-of-the-art review of this operation. The text reviews specific design and selection criteria, both theoretical and practical. There are many actual industrial problems given as a means of further elucidating the principles of filtration that are presented. All of the options and methods for equipment and component functions, as well as engineering design routes, are examined in detail, and optimum systems and functions are specified. Major Sections: Hydrodynamics of Flows Through Porous Media; Introduction to Filtration; Governing Laws of Cake Filtration; Governing Laws of Filter-Medium Filtration; Application of Filter Aids; Filter Media; Cake Washing; Cake Dewatering; Design Equations for Optimum Filtration; Summary of Graphical Analysis Techniques; Liquid Filtration Equipment; Ultrafiltration; Microporous Membrane Filtration; Industrial Applications of Reverse Osmosis Selection and Sizing of Prefilter/Final Filter Systems; Filtration Design Examples; Index.

Cheremisinoff, N.P.; Azbel, D.S.

1983-01-01

336

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

2012-02-10

337

Hyperridge of triply excited states  

NASA Astrophysics Data System (ADS)

We present a theory for the definition and the reliable calculation of correlated wave functions of a special class of triply excited states and for their rigorous geometrical analysis. This class is named the three-electron ionization ladder (THEIL) and refers to the simultaneous excitation of three electrons in valence states near threshold. Application to the Li THEIL of 4S ° symmetry reveals impressive localization properties. In analogy with a similar analysis of the ``two-electron ionization ladder,'' which leads smoothly to the so-called ``Wannier ridge'' at the E=0 threshold, the present results suggest the existence of a ``hyperridge'' at E=0 with the following properties: (1) The ion core and the three electrons lie in a plane, (2) ||r1||=||r2||=||r3||, and (3) ?12=?23=?31. .AE

Komninos, Y.; Chrysos, M.; Nicolaides, C. A.

1988-10-01

338

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.

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

2004-01-01

339

Spatiotemporal control of nanooptical excitations.  

PubMed

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

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

2010-03-08

340

Multiparticle excitations in 194Pb  

Microsoft Academic Search

High-spin states of 194Pb have been populated by the reaction 184W(16O,6n) at 113 MeV beam energy and studied using the EUROGAM-1 array. The level scheme has been extended up to spin of 33? and excitation energy of 11.1 MeV. The high-spin part of the level scheme is dominated by bands of dipole transitions. New dipole bands have been observed and the configurations

M. Kaci; M.-G. Porquet; I. Deloncle; M. Aiche; F. Azaiez; G. Bastin; C. W. Beausang; C. Bourgeois; R. M. Clark; R. Duffait; J. Duprat; B. J. P. Gall; F. Hannachi; K. Hauschild; M. J. Joyce; A. Korichi; Y. Le Coz; M. Meyer; E. S. Paul; N. Perrin; N. Poffé; N. Redon; C. Schück; H. Sergolle; J. F. Sharpey-Schafer; J. Simpson; A. G. Smith; R. Wadsworth

2002-01-01

341

Multiphoton-Excited Serotonin Photochemistry  

Microsoft Academic Search

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)

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

2004-01-01

342

Excited states in 124 Xe  

Microsoft Academic Search

Excited states of124Xe have been investigated via the122Te(?, 2n),114Cd(13C, 3n) and108Pd(19F, p2n) reactions using in-beam gamma-ray and electron spectroscopy methods. 36 new levels and several spin and parity assignments were established, revealing the existence of at least one positive parity superband and two negative parity bands, one of them showing backbending.

W. Gast; U. Kaup; H. Hanewinkel; R. Reinhardt; K. Schiffer; K. P. Schmittgen; K. O. Zell; J. Wrzesinski; A. Gelberg; P. V. Brentano

1984-01-01

343

Excited states in 130Ba  

Microsoft Academic Search

Excited states of 130Ba have been studied by means of in-beam gamma-ray spectroscopy and electron-spectroscopy via the reaction 120Sn(13C, 3n). Spin and parity assignments have been made for 28 new levels. A comparison with a cranking-model calculation shows that the negative-parity band based on the 5- state is a two-quasiproton band.

Sun Xianfu; D. Bazzacco; W. Gast; A. Gelberg; U. Kaup; K. Schiffer; A. Dewald; R. Reinhardt; K. O. Zell; P. von Brentano

1985-01-01

344

Threshold electron excitation of Na  

SciTech Connect

Electron collisional excitation of the 4{ital D}, 5{ital D}, 4{ital P}, and 6{ital S} states of Na has been measured with about 30-meV energy resolution. Very rapid, unresolved threshold onsets are seen for all but the 4{ital P} state, and a near-threshold resonance is suggested by the 5{ital D} data. However, only weak undulations in the cross sections are observed above threshold.

Marinkovic, B.; Wang, P.; Gallagher, A. (Joint Institute for Laboratory Astrophysics, National Institute of Standards and Technology and University of Colorado, Boulder, Colorado 80309-0440 (United States))

1992-09-01

345

On Diversity of Configurations Generated by Excitable Cellular Automata with Dynamical Excitation Intervals  

NASA Astrophysics Data System (ADS)

Excitable cellular automata with dynamical excitation interval exhibit a wide range of space-time dynamics based on an interplay between propagating excitation patterns which modify excitability of the automaton cells. Such interactions leads to formation of standing domains of excitation, stationary waves and localized excitations. We analyzed morphological and generative diversities of the functions studied and characterized the functions with highest values of the diversities. Amongst other intriguing discoveries we found that upper boundary of excitation interval more significantly affects morphological diversity of configurations generated than lower boundary of the interval does and there is no match between functions which produce configurations of excitation with highest morphological diversity and configurations of interval boundaries with highest morphological diversity. Potential directions of future studies of excitable media with dynamically changing excitability may focus on relations of the automaton model with living excitable media, e.g. neural tissue and muscles, novel materials with memristive properties and networks of conductive polymers.

Adamatzky, Andrew

2012-12-01

346

Photoionization of excited molecular states  

SciTech Connect

Rapid advances in laser and detector technologies are making it possible to investigate molecular photophysics and photochemistry in powerful new ways. For example, resonantly enhanced multiphoton ionization (REMPI) measurements, in which the total (or the mass selected) ion current is monitored as a function of laser wavelength, have yielded extensive and often novel information on the spectroscopy of the resonant intermediate states. With the addition of photoelectron spectrometry (PES) to analyze the kinetic energy of the ejected electrons, it is possible to determine the branching ratios into different electronic, vibrational, and rotational levels of the product ion and to focus directly on both the dynamics of the multiphoton ionization process and the photoionization of excited state species. In the present paper, we report several REMPI/PES studies of H/sub 2/ and N/sub 2/. The results reflect both the spectroscopy and the dynamics of photoionization of excited molecular states and are discussed in terms of the selection rules for photoionization and the relative probabilities of photoionization from Rydberg and valence states. In some cases, in accordance with the Franck-Condon principle, the results demonstrate that resonant multiphoton ionization through Rydberg states may be a powerful technique for the production of electronic, vibrational, and rotational state selected ions. However, in other cases, systematic departures from Franck-Condon behavior are observed, which reflect the more subtle dynamics of excited state photoionization.

Dehmer, P.M.; Dehmer, J.L.; Pratt, S.T.

1984-01-01

347

Electronic excitations in finite and infinite polyenes  

Microsoft Academic Search

We study electronic excitations in long polyenes, i.e., in one-dimensional strongly correlated electron systems which are neither infinite nor small. The excitations are described within Hubbard and Pariser-Parr-Pople (PPP) models by means of a multiple-reference double-excitation expansion [P. Tavan and K. Schulten, J. Chem. Phys. 85, 6602 (1986)]. We find that quantized ``transition'' momenta can be assigned to electronic excitations

Paul Tavan; Klaus Schulten

1987-01-01

348

Conformal strip excitation of dielectric resonator antenna  

Microsoft Academic Search

A new excitation scheme that employs a conducting conformal strip is proposed for dielectric resonator antenna (DRA) excitation. The new excitation scheme is successfully demonstrated by using a hemispherical DRA whose exact Green function is found using the mode-matching method. The moment method is used to solve the unknown strip current from which the input impedance is obtained. Novel recurrence

Kwok Wa Leung

2000-01-01

349

Two-photon excitation of aluminium phthalocyanines  

SciTech Connect

A demonstration is given of the feasibility of two-photon excitation of aluminium phthalocyanine and of the pharmaceutical preparation 'Fotosens', used in photodynamic therapy. The excitation source was an Nd:YAG laser emitting at the 1064 nm wavelength. The spectra of the two-photon-excited luminescence were obtained and the two-photon absorption cross sections were determined. (lasers in medicine)

Meshalkin, Yu P; Alfimov, E E; Makukha, V K [Novosibirsk State Technical University, Novosibirsk (Russian Federation); Vasil'ev, N E; Denisov, A N; Ogirenko, A P [Siberian Laser Medicine Centre, Novosibirsk (Russian Federation)

1999-12-31

350

Modeling Faraday Excitation of a Viscous Fluid  

Microsoft Academic Search

Abstract Modeling Faraday Excitation of a Viscous Fluid by Bradley Forrest May 2002 Faraday Excitation is the occurrence of growing surface waves when a ?uid is subjected to periodic forcing. Given a ?uid, Faraday Excitation will occur for some, but not all, values of forcing frequency and amplitude. In this thesis, a viscous ?uid is modeled through linear stability analysis

Bradley Forrest; Andrew Bernofi

351

DSS-14 C-Band Exciter.  

National Technical Information Service (NTIS)

The development and implementation of a C-band exciter for use with the Block IV Receiver-Exciter Subsystem at Deep Space Station 14 (DSS-14) has been completed. The exciter supplements the standard capabilities of the Block IV system by providing a drive...

D. R. Rowan

1989-01-01

352

Hydrodynamic response of viscous fluids under seismic excitation  

SciTech Connect

Hydrodynamic response of liquid-tank systems, such as reactor vessels, spent-fuel pools and liquid storage tanks have been studied extensively in the last decade (Chang et al. 1988; Ma et al. 1991). However, most of the studies are conducted with the assumption of an inviscid fluid. In recent years, the hydrodynamic response of viscous fluids has received increasing attention in high level waste storage tanks containing viscous waste material. This paper presents a numerical study on the hydrodynamic response of viscous fluids in a large 2-D fluid-tank system under seismic excitation. Hydrodynamic responses (i.e. sloshing wave height, fluid pressures, shear stress, etc.) are calculated for a fluid with various viscosities. Four fluid viscosities are considered. They are 1 cp, 120 cp, 1,000 cp and 12,000 cp (1 cp = 1.45 {times} 10{sup {minus}7} lb-sec/in{sup 2}). Note that the liquid sodium of the Liquid-Metal Reactor (LMR) reactor has a viscosity of 1.38 {times} 10{sup {minus}5} lb-sec/in{sup 2} (about 95 cp) at an operational temperature of 900{degree}F. Section 2 describes the pertinent features of the mathematical model. In Section 3, the fundamental sloshing phenomena of viscous fluid are examined. Sloshing wave height and shear stress for fluid with different viscosities are compared. The conclusions are given in Section 4.

Ma, D.C.

1993-08-01

353

Pair-excitation energetics of highly correlated many-body states  

NASA Astrophysics Data System (ADS)

A microscopic approach is developed to determine the excitation energetics of highly correlated quasi-particles in optically excited semiconductors based entirely on a pair-correlation function input. For this purpose, the Wannier equation is generalized to compute the energy per excited electron-hole pair of a many-body state probed by a weak pair excitation. The scheme is verified for the degenerate Fermi gas and incoherent excitons. In a certain range of experimentally accessible parameters, a new stable quasi-particle state is predicted which consists of four to six electron-hole pairs forming a liquid droplet of fixed radius. The energetics and pair-correlation features of these ‘quantum droplets’ are analyzed.

Mootz, M.; Kira, M.; Koch, S. W.

2013-09-01

354

The Liquidity Risk of Liquid Hedge Funds  

Microsoft Academic Search

This paper evaluates hedge funds that grant favorable redemption terms to investors. Within this group of purportedly liquid funds, high net inflow funds subsequently outperform low net inflow funds by 4.79 percent per year after adjusting for risk. The return impact of fund flows is stronger when funds embrace liquidity risk, when market liquidity is low, and when funding liquidity,

Melvyn Teo

2010-01-01

355

The liquidity risk of liquid hedge funds  

Microsoft Academic Search

This paper evaluates hedge funds that grant favorable redemption terms to investors. Within this group of purportedly liquid funds, high net inflow funds subsequently outperform low net inflow funds by 4.79% per year after adjusting for risk. The return impact of fund flows is stronger when funds embrace liquidity risk, when market liquidity is low, and when funding liquidity, as

Melvyn Teo

2011-01-01

356

How Liquid are Liquid Hedge Funds?  

Microsoft Academic Search

Many hedge funds impose minimal share restrictions and allow investors to redeem on a monthly basis or better. We find that there is significant variation in the liquidity risk exposure of these “liquid” funds. Within this group of funds, those that embrace liquidity risk outperform those that eschew liquidity risk by 4.86 percent per year. As a consequence of the

BNP Paribas Hedge Fund Centre; Melvyn Teo

2009-01-01

357

The Liquidity Risk of Liquid Hedge Funds  

Microsoft Academic Search

This paper evaluates hedge funds that grant favorable redemption terms to investors. Within this group of purportedly liquid funds, high net inflow funds subsequently outperform low net inflow funds by 4.79% per year after adjusting for risk. The return impact of fund flows is stronger when funds embrace liquidity risk, when market liquidity is low, and when funding liquidity, as

Song Wee Melvyn TEO

2011-01-01

358

Stochastic resonance in liquid membrane oscillator  

NASA Astrophysics Data System (ADS)

The oil/water liquid membrane oscillator which has been intensively investigated in recent years is generally considered a promising model for excitable biomembranes. The present work deals with the stochastic resonance (SR) phenomena liquid membrane oscillators with the model proposed by Yoshikawa, and the mechanism of SR and some interesting behaviors are also discussed. When SR occurs, the input signal is greatly amplified with the cooperation of noise and the output signal-to-noise ratio is also dramatically enhanced. We consider SR as a possible functional mechanism of some sensory cells.

Zuo, Xiaobing; Hou, Zhonghuai; Xin, Houwen

1998-10-01

359

Excitations of amorphous solid helium  

NASA Astrophysics Data System (ADS)

We present neutron scattering measurements of the dynamic structure factor S(Q,?) of amorphous solid helium confined in 47-Å pore diameter MCM-41 at pressure 48.6 bars. At low temperature T=0.05 K, we observe S(Q,?) of the confined quantum amorphous solid plus the bulk polycrystalline solid between the MCM-41 powder grains. No liquidlike phonon-roton modes, other sharply defined modes at low energy (?< 1.0 meV), or modes unique to a quantum amorphous solid that might suggest superflow are observed. Rather, the S(Q,?) of confined amorphous and bulk polycrystalline solid appear to be very similar. At higher temperature (T> 1 K), the amorphous solid in the MCM-41 pores melts to a liquid which has a broad S(Q,?) peaked near w?0, characteristic of normal liquid 4He under pressure. Expressions for the S(Q,?) of amorphous and polycrystalline solid helium are presented and compared. In previous measurements of liquid 4He confined in MCM-41 at lower pressure, the intensity in the liquid roton mode decreases with increasing pressure until the roton vanishes at the solidification pressure (38 bars), consistent with no roton in the solid observed here.

Bossy, Jacques; Ollivier, Jacques; Schober, Helmut; Glyde, H. R.

2012-12-01

360

Dynamics of Liquid ^4He in GelTek Silica  

NASA Astrophysics Data System (ADS)

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

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

2000-03-01

361

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

362

Excitation transfer induced spectral diffusion and the influence of structural spectral diffusion  

NASA Astrophysics Data System (ADS)

The theory of vibrational excitation transfer, which causes spectral diffusion and is also influenced by structural spectral diffusion, is developed and applied to systems consisting of vibrational chromophores. Excitation transfer induced spectral diffusion is the time-dependent change in vibrational frequency induced by an excitation on an initially excited molecule jumping to other molecules that have different vibrational frequencies within the inhomogeneously broadened vibrational absorption line. The excitation transfer process is modeled as Förster resonant transfer, which depends on the overlap of the homogeneous spectra of the donating and accepting vibrational chromophores. Because the absorption line is inhomogeneously broadened, two molecules in close proximity can have overlaps of their homogeneous lines that range from substantial to very little. In the absence of structural dynamics, the overlap of the homogeneous lines of the donating and accepting vibrational chromophores would be fixed. However, dynamics of the medium that contains the vibrational chromophores, e.g., a liquid solvent or a surrounding protein, produce spectral diffusion. Spectral diffusion causes the position of a molecule's homogeneous line within the inhomogeneous spectrum to change with time. Therefore, the overlap of donating and accepting molecules' homogeneous lines is time dependent, which must be taken into account in the excitation transfer theory. The excitation transfer problem is solved for inhomogeneous lines with fluctuating homogeneous line frequencies. The method allows the simultaneous treatment of both excitation transfer induced spectral diffusion and structural fluctuation induced spectral diffusion. It is found that the excitation transfer process is enhanced by the stochastic fluctuations in frequencies. It is shown how a measurement of spectral diffusion can be separated into the two types of spectral diffusion, which permits the structural spectral diffusion to be determined in the presence of excitation transfer spectral diffusion. Various approximations and computational methodologies are explored.

Rosenfeld, Daniel E.; Fayer, Michael D.

2012-08-01

363

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

364

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

365

Multiharmonic excitation for nonlinear system identification  

NASA Astrophysics Data System (ADS)

Parametric identification of nonlinear systems is done using a hybrid time/frequency-domain-based Fourier series identification method. A multiharmonic force excitation is proposed to overcome identification problems encountered with a single harmonic excitation for certain classes of nonlinear systems. A Duffing oscillator and a system with quadratic damping are considered in detail for illustration of the proposed identification scheme using multiharmonic excitation. It is demonstrated that for most situations a multiharmonic excitation leads to significantly better identification results than a single harmonic excitation-based method.

Narayanan, M. D.; Narayanan, S.; Padmanabhan, Chandramouli

2008-04-01

366

Photoionization of excited molecular states using multiphoton excitation techniques  

SciTech Connect

Photoelectron spectra are reported for three photon resonant, four photon ionization of H/sub 2/ via the B /sup 1/..sigma../sub u//sup +/, v = 7 (J = 2,4) and C /sup 1/..pi../sub u'/, v = 0-4 (J = 1) levels and of N/sub 2/ via the o/sub 3//sup 1/..pi../sub u'/, v = 1,2, b /sup 1/..pi../sub u'/, v = 3-5, and c /sup 1/..pi../sub u'/, v = 0 levels. The results reflect both the spectroscopy and the dynamics of photoionization of excited molecular states and are discussed in terms of the selection rules for photoionization and the relative probabilities of photoionization from Rydberg and valence states. In some cases, in accordance with the Franck-Condon principle, the results demonstrate that resonant multiphoton ionization through Rydberg states may be a powerful technique for the production of electronic, vibrational, and rotational state selected ions. However, in other cases, systematic departures from Franck-Condon factors are observed, which reflect the more subtle dynamics of excited state photoionization. 23 references, 6 figures, 2 tables.

Dehmer, P.M.; Pratt, S.T.; Dehmer, J.L.

1984-01-01

367

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

368

Ultrafast Conversions Between Hydrogen Bonded Structures in Liquid Water Observed by Femtosecond X-Ray Spectroscopy.  

National Technical Information Service (NTIS)

We present the first femtosecond soft x-ray spectroscopy in liquids, enabling the observation of changes in hydrogen bond structures in water via core-hole excitation. The oxygen K-edge of vibrationally excited water is probed with femtosecond soft x-ray ...

A. M. Lindenberg H. Wen N. Huse R. W. Schoenlein

2010-01-01

369

LIFETIME SHORTENING FROM MICRO TO NANO IN COPPER DOPED CaS AT LIQUID NITROGEN TEMPERATURE  

Microsoft Academic Search

Copper doped Calcium sulphide phosphors having variable concentrations of killer impurities Fe, Co and Ni have been synthesized and then using laser excitation of samples for there photoluminescence behaviour, their decay-curve analysis has been done. Various strong emissions in these phosphors have been detected and the corresponding excited state lifetimes are measured at liquid nitrogen temperature. Studies have also been

SUNIL KUMAR; N. K. VERMAa; S. K. CHAKARVARTIb; J. K. SHARMA

370

Stochastic model for microgravity excitation  

NASA Astrophysics Data System (ADS)

A simple stochastic method for generating synthetic orbital accelerations is proposed in this paper. The procedure is used to develop a stochastic model for the STS-40 orbital excitation. The method uses a filtered white-noise model that takes into account time evolutions of the amplitude and the frequency content of the original accelerogram. The probabilistic response spectra are generated and comparisons with those of the actual STS-40 orbital data are made to verify the model. The results indicate that significant properties of the original record are retained in the generated synthetic accelerations. This method is also employed to generate a stochastic model for the space station vibration environment.

Ellison, Joseph; Ahmadi, Goodarz; Grodsinsky, Carlos

1995-04-01

371

Nucleon resonance excitation with CLAS  

SciTech Connect

The study of the baryon spectrum is a fundamental part of the scientific program in Hall B at Jefferson Laboratory. The so called N* program indeed concerns the measurement of the electromagnetic production of exclusive hadronic final states, with the purpose of extracting information on baryon excited states. CLAS, the CEBAF Large Acceptance Spectrometer, is explicitly designed for conducting a broad experimental program in hadronic physics, using the continuous electron beam provided by the laboratory. An overview of the most recent results is presented.

R. De Vita; CLAS Collaboration

2004-09-01

372

Nuclear excitations and reaction mechanisms  

NASA Astrophysics Data System (ADS)

Research concerning nuclear excitations and reaction mechanisms is described. Among the various subjects discussed are: photon scattering, consistency condition between seagull quadrapole terms and the absorption sum rule, Raman scattering to negative-parity states, non-local terms due to exchange and retardation effects in charge-transfer equations, consistency and meaning of various approximate channel coupling array equations, derivation of equations used in empirical nuclear reaction analyses, multi-cluster n-particle scattering theory, converged molecular bound state calculations, and WKB-type approximation in angular momenta for central potentials.

Fallieros, S.; Levin, S. F.; Li, C. T.

1980-10-01

373

Spin Correlations in Quantum Spin Liquids on the Kagome Lattice  

NASA Astrophysics Data System (ADS)

The spin-1/2 Heisenberg kagome antiferromagnet, due to its highly frustrated nature, is considered a prime candidate to realize a spin-liquid ground state that breaks no symmetry and hosts fractionalized magnetic excitations. Recent numerical results indicate a close competition for the ground state between different spin-liquid states. We study spin correlations in competing phases, suggest possible experiments to distinguish different ground states, and discuss the application of these ideas to Herbertsmithite.

Dodds, Tyler; Kim, Yong Baek

2013-03-01

374

Vibrationally Excited C6H  

NASA Astrophysics Data System (ADS)

Rotational spectra of the linear carbon chain radical C6H in two low-lying excited vibrational states were observed both at millimeter wavelengths in a low-pressure glow discharge and at centimeter wavelengths in a supersonic molecular beam. Two series of harmonically related lines with rotational constants within 0.3% of the 2? ground state were assigned to the 2? and 2? vibronic components of an excited bending vibrational level. Measurements of the intensities of the lines in the glow discharge indicate that the 2? component lies very close to ground, but the 2? component is much higher in energy. The standard Hamiltonian for an isolated 2? state with five spectroscopic constants reproduces the observed rotational spectrum, but several high-order distortion terms in the spin-rotation interaction are needed to reproduce the spectrum of the 2? component in C6H and C6D. The derived spectroscopic constants allow astronomers to calculate the rotational spectra of the 2? and 2? states up to 260 GHz to within 0.1 km s-1 or better in equivalent radial velocity.

Gottlieb, C. A.; McCarthy, M. C.; Thaddeus, P.

2010-08-01

375

Coulomb excitation of Ga73  

NASA Astrophysics Data System (ADS)

The B(E2;Ii?If) values for transitions in 3171Ga40 and 3173Ga42 were deduced from a Coulomb excitation experiment at the safe energy of 2.95 MeV/nucleon using post-accelerated beams of Ga71,73 at the REX-ISOLDE on-line isotope mass separator facility. The emitted ? 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 Sn120 target. The comparison of these new results with the data of less neutron-rich gallium isotopes shows a shift of the E2 collectivity toward 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 isotopic chain between N=40 and 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 3173Ga42 differing by at most 0.8 keV in energy.

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

2010-12-01

376

Gapless spin liquids: Stability and possible experimental relevance  

NASA Astrophysics Data System (ADS)

For certain crystalline systems, most notably the organic compound EtMe3Sb[Pd(dmit)2]2, experimental evidence has accumulated of an insulating state with a high density of gapless neutral excitations that produce Fermi-liquid-like power laws in thermodynamic quantities and thermal transport. This has been taken as evidence of a fractionalized spin-liquid state. In this Rapid Communication, we argue that if the experiments are taken at face value, the most promising spin-liquid candidates are a Z4 spin liquid with a spinon-Fermi surface and no broken symmetries, or a Z2 spin liquid with a spinon-Fermi surface and at least one of the following spontaneously broken: (a) time-reversal and inversion, (b) translation, or (c) certain point-group symmetries. We present a solvable model on the triangular lattice with an (a) type Z2 spin-liquid ground state.

Barkeshli, Maissam; Yao, Hong; Kivelson, Steven A.

2013-04-01

377

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

378

Ultraviolet Excitation Photothermal Spectroscopy of Non-Labeled Amino Acids and Visible Light-Induced Signal Enhancement  

NASA Astrophysics Data System (ADS)

A measurement system for ultraviolet-laser excitation photothermal lens spectroscopy has been designed and constructed for measuring dilute amino acids in liquid solutions. An ultraviolet laser beam is generated as the fourth harmonic of a Ti:sapphire laser in the wavelength range of 212 to 220 nm. Photothermal lens spectra of alanine, phenylalanine, serine, and tryptophan are observed. Photothermal lens spectra of these samples are coincident with their absorption spectra. It is demonstrated that photothermal lens signals of the amino acids can be amplified by simultaneous excitation with a visible laser. This ultraviolet-excitation visible-enhancement system is applicable to photoacoustic detection.

Hirashima, Satoshi; Harata, Akira

2008-05-01

379

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 Åis 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 Nozières( J. Gavoret and P. Nozières, 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

380

Spin liquid regimes at nonzero temperature in quantum spin ice  

NASA Astrophysics Data System (ADS)

Quantum spin liquids are highly entangled ground states of quantum systems with an emergent gauge structure, fractionalized spinon excitations, and other unusual properties. While these features clearly distinguish quantum spin liquids from conventional, mean-field-like states at zero temperature (T), their status at T>0 is less clear. Strictly speaking, it is known that most quantum spin liquids lose their identity at nonzero temperature, being then adiabatically transformable into a trivial paramagnet. This is the case for the U(1) quantum spin liquid states recently proposed to occur in the quantum spin ice pyrochlores. Here we propose, however, that in practical terms, the latter quantum spin liquids can be regarded as phases distinct from the high-temperature paramagnet. Through a combination of gauge mean-field theory calculations and physical reasoning, we argue that these systems sustain both quantum spin liquid and thermal spin liquid phases, dominated by quantum fluctuations and entropy, respectively. These phases are separated by a first-order “thermal confinement” transition such that, for temperatures below the transition, spinons and emergent photons are coherently propagating excitations, and above it the dynamics is classical. Even for parameters for which the ground state is magnetically ordered and not a quantum spin liquid, this strong first-order transition occurs, preempting conventional Landau-type criticality. We argue that this picture explains the anomalously low-temperature phase transition observed in the quantum spin ice material Yb2Ti2O7.

Savary, Lucile; Balents, Leon

2013-05-01

381

Liquid-liquid-solid transition in viscoelastic liquids  

PubMed Central

Liquid-liquid-solid transitions (LLST) are known to occur in confined liquids, exist in supercooled liquids and emerge in liquids driven from equilibrium. Molecular dynamics (MD) simulations claim many successes in forecasting the phenomena. The transitions are also studied in the framework of thermodynamics based methods and minimalistic models. In here, the proposed approach is derived in the framework of continuum and includes spatial and temporal dynamic heterogeneities; the approach is meant to capture the material behavior at small scales. We conjecture that the liquid-like and solid-like behaviors are dissimilar enough for the two to be governed by different constitutive relations. In this way, we gain additional degree of freedom, which is found essential when predicting the transitional phenomena. As a result, we derive the LLST criteria for liquids in equilibrium, during steady flow and at transient conditions. Lastly, we forecast short-lived LLSTs in human blood during cardiac cycle.

Zubelewicz, Aleksander

2013-01-01

382

Controlling the coexistence of structural phases and the optical properties of gallium nanoparticles with optical excitation  

NASA Astrophysics Data System (ADS)

We have observed reversible structural transformations, induced by optical excitation at 1.55 ?m, between the ?, ? and liquid phases of gallium in self-assembled gallium nanoparticles, with a narrow size distribution around 50 nm, on the tip of an optical fiber. Only a few tens of nanowatts of optical excitation per particle are required to control the transformations, which take the form of a dynamic phase coexistence and are accompanied by substantial changes in the optical properties of the nanoparticle film. The time needed to achieve phase equilibrium is in the microsecond range, and increases sharply near the transition temperatures.

MacDonald, K. F.; Fedotov, V. A.; Pochon, S.; Stevens, G.; Kusmartsev, F. V.; Emel'yanov, V. I.; Zheludev, N. I.

2004-08-01

383

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.

384

Lacerations - liquid bandage  

MedlinePLUS

... medical attention. If the cut is minor, a liquid bandage (liquid adhesive) can be used on the cut to ... the wound and help stop bleeding. Using a liquid bandage is quick and painless to apply. Skin ...

385

Liquid Crystal Institute  

NSDL National Science Digital Library

The Liquid Crystal Institute website provides information on the interdisciplinary research and development of liquid crystal optoelectronic materials, technology, and consumer products. It provides basic information on what liquid crystals are as well as how they are made and used.

Institute, Liquid C.

2003-10-10

386

Final excitation energy of fission fragments  

SciTech Connect

We study how the excitation energy of the fully accelerated fission fragments is built up. It is stressed that only the intrinsic excitation energy available before scission can be exchanged between the fission fragments to achieve thermal equilibrium. This is in contradiction with most models used to calculate prompt neutron emission, where it is assumed that the total excitation energy of the final fragments is shared between the fragments by the condition of equal temperatures. We also study the intrinsic excitation-energy partition in statistical equilibrium for different level-density descriptions as a function of the total intrinsic excitation energy of the fissioning system. Excitation energies are found to be strongly enhanced in the heavy fragment, if the level density follows a constant-temperature behavior at low energies, e.g., in the composed Gilbert-Cameron description.

Schmidt, Karl-Heinz; Jurado, Beatriz [Centre d'Etudes Nucleaires de Bordeaux Gradignan (CENBG), CNRS/IN2P3, Chemin du Solarium, B.P. 120, F-33175 Gradignan (France)

2011-06-15

387

Asymptotic Bethe-ansatz solution of multicomponent quantum systems with 1/r2 long-range interaction  

NASA Astrophysics Data System (ADS)

Asymptotic Bethe-ansatz solutions are obtained for one-dimensional quantum systems with a 1/r2 long-range interaction by generalizing Sutherland's method to multicomponent quantum systems. We obtain the solutions to the supersymmetric t-J model of Kuramoto and Yokoyama, the SU(?) Haldane-Shastry model, and the multicomponent t-J model. The excitation spectrum as well as bulk quantities are computed analytically. Conformal properties of low-energy excitations are discussed in connection with Luttinger liquid theory.

Kawakami, Norio

1992-07-01

388

Longitudinal excitations in quantum antiferromagnets.  

PubMed

By extending our recently proposed magnon-density waves to low dimensions, we investigate, using a microscopic many-body approach, the longitudinal excitations of the quasi-one-dimensional (quasi-1d) and quasi-2d Heisenberg antiferromagnetic systems on a bipartite lattice with a general spin quantum number. We obtain the full energy spectrum of the longitudinal mode as a function of the coupling constants in the original lattice Hamiltonian and find that it always has a nonzero energy gap if the ground state has a long-range order and becomes gapless for the pure isotropic 1d model. The numerical value of the minimum gap in our approximation agrees with that of a longitudinal mode observed in the quasi-1d antiferromagnetic compound KCuF(3) at low temperature. It will be interesting to compare values of the energy spectrum at other momenta if their experimental results are available. PMID:21841234

Xian, Y

2011-08-12

389

Excited Baryon Production and Decays  

NASA Astrophysics Data System (ADS)

We consider decays of the lowest-lying positive parity (56-plet) and negative parity (70-plet) excited baryons. For the 70-plet, we include both single-quark and two-quark decay operators, and find, somewhat mysteriously, that the two-quark operators are not phenomenologically important. Studies of decays 70 ? ? + ? may strengthen or vitiate this observation. For the 56-plet decays, now using only the single-quark operator, we can predict many strong decays after fitting parameters on the assumption that the Roper is a 3q state. Comparison of these predictions to experiment can verify the structure of the 56-plet. As a sidelight, we show a large Nc derivation of the old Gürsey-Radicati mass formula.

Carlson, Carl E.

2002-09-01

390

Collective excitations of supersymmetric plasma  

NASA Astrophysics Data System (ADS)

Collective excitations of N=1 supersymmetric electromagnetic plasma are studied. Since the Keldysh-Schwinger approach is used, not only equilibrium but also nonequilibrium plasma, which is assumed to be ultrarelativistic, is under consideration. The dispersion equations of photon, photino, electron, and selectron modes are written down and the self-energies, which enter the equations, are computed in the hard loop approximation. The self-energies are discussed in the context of effective action which is also given. The photon modes and electron ones appear to be the same as in the usual ultrarelativistic plasma of electrons, positrons, and photons. The photino modes coincide with the electron ones and the selectron modes are as of a free relativistic massive particle.

Czajka, Alina; Mrówczy?ski, Stanis?aw

2011-02-01

391

Propagation failure in excitable media  

SciTech Connect

We study a mechanism of pulse propagation failure in excitable media where stable traveling pulse solutions appear via a subcritical pitchfork bifurcation. The bifurcation plays a key role in that mechanism. Small perturbations, externally applied or from internal instabilities, may cause pulse propagation failure (wave breakup) provided the system is close enough to the bifurcation point. We derive relations showing how the pitchfork bifurcation is unfolded by weak curvature or advective field perturbations and use them to demonstrate wave breakup. We suggest that the recent observations of wave breakup in the Belousov-Zhabotinsky reaction induced by either an electric field [J.J. Taboada {ital et al.}. Chaos {bold 4}, 519 (1994)] or a transverse instability [M. Markus, G. Kloss, and I. Kusch, Nature (London) {bold 371}, 402 (1994)] are manifestations of this mechanism. {copyright} {ital 1998} {ital The American Physical Society}

Hagberg, A. [Center for Nonlinear Studies and T-7, Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Meron, E. [The Jacob Blaustein Institute for Desert Research and the Physics Department, Ben-Gurion University, Sede Boker Campus 84990, Sede Boker (Israel)

1998-01-01

392

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

393

Solids Liquids and Gases  

NSDL National Science Digital Library

Compare and contrast the three states of matter: solids, liquids and gases. First you will begin by looking at characteristics of each solids, liquids and gasesGases, Liquids and Solids Facts. Then you will look at examples of each stateSolids, Liquids and Gases Video. Demonstrate an understanding of solids, liquids and gases by playing interactive gameSolids, Liquids and Gases Game. Graphic Organizer is here to be filled out as you learn during this lesson. Use the red ...

Salter, Ms.

2009-10-22

394

Hybrid Excitation of the Axial Inductor Machine  

NASA Astrophysics Data System (ADS)

The paper considers the possibility to use permanent magnets in the rotor slots of axial inductor machine with the aim to create a hybrid excitation of such a machine - from the magnets and from the excitation winding which is placed between the stator cores. The hybrid excitation allows the weight and size parameters of the machine to be improved. Under consideration is a 32 kW under-carriage generator 2?B.13.Y1.

Orlova, S.; Pugachov, V.; Levin, N.

2012-01-01

395

Universal Dynamical Computation in Multidimensional Excitable Lattices  

Microsoft Academic Search

We study two- and three-dimensional latticesnodes of which take three states: rest, eccited, andrefractory, and deterministically update their states indiscrete time depending on the number of excited closest neighbors. Every resting node isexcited if exactly 2 of its 8 (in two-dimensionallattice) or exactly 4 of its 26 (in three-dimensionallattice) closest neighbors are excited. A node changesits excited state into the

Andrew Adamatzky

1998-01-01

396

REDISTRIBUTOR FOR LIQUID-LIQUID EXTRACTION COLUMNS  

DOEpatents

An improved baffle plate construction to intimately mix immiscible liquid solvents for solvent extraction processes in a liquid-liquid pulse column is described. To prevent the light and heavy liquids from forming separate continuous homogeneous vertical channels through sections of the column, a baffle having radially placed rectangular louvers with deflection plates opening upon alternate sides of the baffle is placed in the column, normal to the axis. This improvement substantially completely reduces strippiig losses due to poor mixing.

Bradley, J.G.

1957-10-29

397

Effects of acoustic excitation positions on heat transfer and flow in axisymmetric impinging jet: main jet excitation and shear layer excitation  

Microsoft Academic Search

An experimental study is conducted to investigate the flow and heat transfer characteristics of an impinging jet with acoustic excitations. Two different acoustic excitation methods based on the locations of the actuator are tested and compared: one is a main jet excitation and the other is a shear layer excitation. Effects of excitation level on the heat transfer and flow

S. D Hwang; H. H Cho

2003-01-01

398

Periodic acceptor excitation spectroscopy of single molecules  

PubMed Central

Alternating-laser excitation (ALEX) spectroscopy has recently been added to the single-molecule spectroscopy toolkit. ALEX monitors interaction and stoichiometry of biomolecules, reports on biomolecular structure by measuring accurate Förster resonance energy transfer (FRET) efficiencies, and allows sorting of subpopulations on the basis of stoichiometry and FRET. Here, we demonstrate that a simple combination of one continuous-wave donor-excitation laser and one directly modulated acceptor-excitation laser (Periodic Acceptor eXcitation) is sufficient to recapitulate the capabilities of ALEX while minimizing the cost and complexity associated with use of modulation techniques.

Doose, Soren; Heilemann, Mike; Michalet, Xavier; Weiss, Shimon

2011-01-01

399

Periodic acceptor excitation spectroscopy of single molecules.  

PubMed

Alternating-laser excitation (ALEX) spectroscopy has recently been added to the single-molecule spectroscopy toolkit. ALEX monitors interaction and stoichiometry of biomolecules, reports on biomolecular structure by measuring accurate Förster resonance energy transfer (FRET) efficiencies, and allows sorting of subpopulations on the basis of stoichiometry and FRET. Here, we demonstrate that a simple combination of one continuous-wave donor-excitation laser and one directly modulated acceptor-excitation laser (Periodic Acceptor eXcitation) is sufficient to recapitulate the capabilities of ALEX while minimizing the cost and complexity associated with use of modulation techniques. PMID:17279362

Doose, Sören; Heilemann, Mike; Michalet, Xavier; Weiss, Shimon; Kapanidis, Achillefs N

2007-02-06

400

Rydberg Excitation of Bose-Einstein Condensates  

SciTech Connect

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

Heidemann, Rolf; Raitzsch, Ulrich; Bendkowsky, Vera; Butscher, Bjoern; Loew, Robert; Pfau, Tilman [5. Physikalisches Institut, Universitaet Stuttgart, Pfaffenwaldring 57, 70569 Stuttgart (Germany)

2008-01-25

401

Rydberg excitation of Bose-Einstein condensates.  

PubMed

Rydberg atoms provide a wide range of possibilities to tailor interactions in a quantum gas. Here, we report on Rydberg excitation of Bose-Einstein condensed 87Rb atoms. The Rydberg fraction was investigated for various excitation times and temperatures above and below the condensation temperature. The excitation is locally blocked by the van der Waals interaction between Rydberg atoms to a density-dependent limit. Therefore, the abrupt change of the thermal atomic density distribution to the characteristic bimodal distribution upon condensation could be observed in the Rydberg fraction. The observed features are reproduced by a simulation based on local collective Rydberg excitations. PMID:18232977

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

2008-01-22

402

Mollow quintuplets from coherently excited quantum dots.  

PubMed

Charge-neutral excitons in semiconductor quantum dots (QDs) have a small finite energy separation caused by the anisotropic exchange splitting. Coherent excitation of neutral excitons will generally excite both exciton components, unless the excitation is parallel to one of the dipole axes. We present a polaron master equation model to describe two-exciton pumping using a coherent continuous wave pump field in the presence of a realistic anisotropic exchange splitting. We predict a five-peak incoherent spectrum, namely a Mollow quintuplet under general excitation conditions. We experimentally confirm such spectral quintuplets for In(Ga)As QDs and obtain very good agreement with theory. PMID:23938913

Ge, Rong-Chun; Weiler, S; Ulhaq, A; Ulrich, S M; Jetter, M; Michler, P; Hughes, S

2013-05-15

403

Random lasing in blue phase liquid crystals.  

PubMed

Random lasing actions have been observed in optically isotropic pure blue-phase and polymer-stabilized blue-phase liquid crystals containing laser dyes. Scattering, interferences and recurrent multiple scatterings arising from disordered platelet texture as well as index mismatch between polymer and mesogen in these materials provide the optical feedbacks for lasing action. In polymer stabilized blue-phase liquid crystals, coherent random lasing could occur in the ordered blue phase with an extended temperature interval as well as in the isotropic liquid state. The dependence of lasing wavelength range, mode characteristics, excitation threshold and other pertinent properties on temperature and detailed make-up of the crystals platelets were obtained. Specifically, lasing wavelengths and mode-stability were found to be determined by platelet size, which can be set by controlling the cooling rate; lasing thresholds and emission spectrum are highly dependent on, and therefore can be tuned by temperature. PMID:23188364

Chen, Chun-Wei; Jau, Hung-Chang; Wang, Chun-Ta; Lee, Chun-Hong; Khoo, I C; Lin, Tsung-Hsien

2012-10-01

404

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

405

Fluorinated liquid crystals--properties and applications.  

PubMed

This critical review begins with a brief, but essential, introduction to the special nature of liquid crystal materials, their peculiar properties, and their commercial applications, followed by an introductory insight into the remarkable nature of the fluoro substituent, and its fascinating influence on the properties of organic compounds. However, the main focus of the review is to discuss the enormous amount of exciting research on fluorinated liquid crystals that has been reported. The small size of the fluoro substituent enables its incorporation into all types of liquid crystal, including calamitic, discotic, banana, lyotropic, and polymers, without ruining the liquid crystalline nature of the material. However the fluoro substituent is larger than hydrogen, and hence causes a significant steric effect, which combined with the high polarity, confers many fascinating, and often remarkable, modifications to melting point, mesophase morphology and transition temperatures, and the many other very important physical properties, such as dielectric anisotropy, optical anisotropy, and visco-elastic properties. There are many different positions within a liquid crystal structure where a fluoro substituent can be located, including (i) a terminal position, (ii) within a terminal chain, as a semi-fluorinated or as a perfluorinated chain, or as one fluoro substituent at a chiral centre, (iii) as part of a linking group, and (iv) a lateral position in the core section. Such variety enables the interesting and advantageous tailoring of properties, both for the fundamental purposes of establishing structure-property relationships, and for materials targeted towards commercially-successful liquid crystal display applications. PMID:17982522

Hird, Michael

2007-09-14

406

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

407

Liquid Layer Model for Non-Magic Nuclei.  

National Technical Information Service (NTIS)

A liquid layer model (LLM) is developed for studying the low-energy oscillations of non-magic spherical nuclei. It is assumed that at low excitations only nucleons off the double-magic core take part in the collective motion. These nuclear states are mode...

S. I. Bastrukov G. Kluge A. V. Tarakanov

1989-01-01

408

Laser fluorescence detection for high-performance liquid chromatography  

Microsoft Academic Search

The excellent sensitivity and selectivity of high performance liquid chromatography (HPLC) with laser fluorescence detection is demonstrated with examples in the biological and environmental fields. The spectral advantages of laser excitation for fluorescence HPLC detection, most notably the high output power of the laser, were discussed and then illustrated for the low picogram level determination of the antitumor drugs adriamycin

Sepaniak

1981-01-01

409

Thermal-transport Studies of Quantum Spin Liquids  

Microsoft Academic Search

Quantum spins, coupling antiferromagnetically on a 2D triangular lattice, cannot simultaneously satisfy all interactions. This frustrated situation is expected to give rise to mysterious fluid-like states of spins without long- range order, so called quantum spin liquid (QSL). The ground state of QSL and its exotic phenomena, such as fractionalized excitation with an artificial gauge field, have been extensively discussed

Minoru Yamashita

2011-01-01

410

Algebraic Spin Liquid in an Exactly Solvable Spin Model.  

National Technical Information Service (NTIS)

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 ...

H. Yao S. Zhang S. A. Kivelson

2009-01-01

411

Chemical dynamics of vibrationally excited molecules: Controlling reactions in gases and on surfaces.  

PubMed

Experimental studies of the chemical reaction dynamics of vibrationally excited molecules reveal the ability of different vibrations to control the course of a reaction. This Perspective describes those studies for the prototypical reaction of vibrationally excited methane and its isotopologues in gases and on surfaces and looks to the prospects of similar studies in liquids. The influences of vibrational excitation on the C-H bond cleavage in a single collision reaction with Cl and in dissociative adsorption on a Ni surface bear some striking similarities. Both reactions are bond-selective processes in which the initial preparation of a molecular eigenstate containing a large component of C-H stretching results in preferential cleavage of that bond. It is possible to cleave either the C-H bond or C-D bond in the reaction of Cl with CH3D, CH2D2, or CHD3 and, similarly, to use initial excitation of the C-H stretch to promote dissociation of CHD3 to CD3 and H on a Ni surface. Different vibrational modes, such as the symmetric and antisymmetric stretches in CH3D or CH4, lead to very different reactivities, and molecules with the symmetric stretching vibration excited can be as much as 10 times more reactive than ones with the antisymmetric stretch excited. The origin of this behavior lies in the change in the vibrational motion induced by the interaction with the atomic reaction partner or the surface. PMID:18765816

Crim, F Fleming

2008-09-02

412

Chemical dynamics of vibrationally excited molecules: Controlling reactions in gases and on surfaces  

PubMed Central

Experimental studies of the chemical reaction dynamics of vibrationally excited molecules reveal the ability of different vibrations to control the course of a reaction. This Perspective describes those studies for the prototypical reaction of vibrationally excited methane and its isotopologues in gases and on surfaces and looks to the prospects of similar studies in liquids. The influences of vibrational excitation on the CH bond cleavage in a single collision reaction with Cl and in dissociative adsorption on a Ni surface bear some striking similarities. Both reactions are bond-selective processes in which the initial preparation of a molecular eigenstate containing a large component of CH stretching results in preferential cleavage of that bond. It is possible to cleave either the CH bond or CD bond in the reaction of Cl with CH3D, CH2D2, or CHD3 and, similarly, to use initial excitation of the CH stretch to promote dissociation of CHD3 to CD3 and H on a Ni surface. Different vibrational modes, such as the symmetric and antisymmetric stretches in CH3D or CH4, lead to very different reactivities, and molecules with the symmetric stretching vibration excited can be as much as 10 times more reactive than ones with the antisymmetric stretch excited. The origin of this behavior lies in the change in the vibrational motion induced by the interaction with the atomic reaction partner or the surface.

Crim, F. Fleming

2008-01-01

413

Supersymmetric Chern-Simons theory and supersymmetric quantum Hall liquid  

SciTech Connect

We develop a supersymmetric extension of Chern-Simons theory and Chern-Simons-Landau-Ginzburg theory for the supersymmetric quantum Hall liquid. Supersymmetric counterparts of topological and gauge structures peculiar to the Chern-Simons theory are inspected in the supersymmetric Chern-Simons theory. We also explore an effective field theoretical description for the supersymmetric quantum Hall liquid. The key observation is the charge-flux duality. Based on the duality, we derive a dual supersymmetric Chern-Simons-Landau-Ginzburg theory, and discuss physical properties of the topological excitations in the supersymmetric quantum Hall liquid.

Hasebe, Kazuki [Department of General Education, Takuma National College of Technology, Takuma-cho, Mitoyo-city, Kagawa 769-1192 (Japan)

2006-08-15

414

Liquid crystal fibers of bent-core molecules  

NASA Astrophysics Data System (ADS)

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

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

2003-05-01

415

Quasiparticle breakdown in a quantum spin liquid.  

PubMed

Much of modern condensed matter physics is understood in terms of elementary excitations, or quasiparticles--fundamental quanta of energy and momentum. Various strongly interacting atomic systems are successfully treated as a collection of quasiparticles with weak or no interactions. However, there are interesting limitations to this description: in some systems the very existence of quasiparticles cannot be taken for granted. Like unstable elementary particles, quasiparticles cannot survive beyond a threshold where certain decay channels become allowed by conservation laws; their spectrum terminates at this threshold. Such quasiparticle breakdown was first predicted for an exotic state of matter--super-fluid 4He at temperatures close to absolute zero, a quantum Bose liquid where zero-point atomic motion precludes crystallization. Here we show, using neutron scattering, that quasiparticle breakdown can also occur in a quantum magnet and, by implication, in other systems with Bose quasiparticles. We have measured spin excitations in a two-dimensional quantum magnet, piperazinium hexachlorodicuprate (PHCC), in which spin-1/2 copper ions form a non-magnetic quantum spin liquid, and find remarkable similarities with excitations in superfluid 4He. We observe a threshold momentum beyond which the quasiparticle peak merges with the two-quasiparticle continuum. It then acquires a finite energy width and becomes indistinguishable from a leading-edge singularity, so that excited states are no longer quasiparticles but occupy a wide band of energy. Our findings have important ramifications for understanding excitations with gapped spectra in many condensed matter systems, ranging from band insulators to high-transition-temperature superconductors. PMID:16525467

Stone, Matthew B; Zaliznyak, Igor A; Hong, Tao; Broholm, Collin L; Reich, Daniel H

2006-03-01

416

Liquid core waveguide for full imaging of electrophoretic separations.  

PubMed

We employed a liquid core waveguide to image both DNA electrophoresis separations and isoelectric focusing of proteins. The utility of the system is demonstrated for DNA fragment sizing and protein separations. The system utilizes the liquid-core waveguide as an efficient window for both the excitation of separated samples and the collection of light through total internal reflectance, with an ability to detect target molecules in the zeptomolar range. Scanning the excitation laser along the length of the electrophoresis capillary excites individually separated analyte bands, while the fluorescence is collected end-on by an optical fiber coupled to a photomultiplier, thus, creating an image of the separation along the length of the capillary. PMID:12033300

Olivares, José A; Stark, Peter C; Jackson, Paul

2002-05-01

417

Micro-dynamics in 2D Dusty Plasma Liquids  

NASA Astrophysics Data System (ADS)

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

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

2002-12-01

418

Self assembled liquid crystal polymers on photo-irradiated alignment surfaces for tailoring response properties of liquid crystal molecules.  

PubMed

A liquid crystal polymer (LCP) self-assembled on a photoirradiated substrate can modify the viscoelastic response of liquid crystal medium on the substrate. Sum-frequency vibrational spectroscopy shows that the phenyl groups of LCP are oriented epitaxially with layer thickness and an in-plane alignment order much higher than that at the photoirradiated surface can be yielded. The liquid crystal molecules confined between the LCP-coated substrates reveals a stronger correlation among the thermally excited fluctuation modes. Our finding can be used to tailor the boundary forces on alignment substrates and to optimize the device performance. PMID:21902209

Huang, Jung Y; Li, Liu S

2011-09-28

419

Ion excited auger spectra of aluminum  

Microsoft Academic Search

An Auger spectrum from aluminum has been detected for the first time using argon ion bombardment as the method for excitation. The Auger spectral line shape differs from that obtained using electron excitation. Research was sponsored by the Air Force Aerospace Research Laboratories, Air Force Systems Command, United States Air Force, Contract F33615-74-C-4017.

T. W. Haas; R. W. Springer; M. P. Hooker; J. T. Grant

1974-01-01

420

Invasion Waves in Populations with Excitable Dynamics  

Microsoft Academic Search

Whilst the most obvious mechanism for a biological invasion is the occupation of a new territory as a result of direct ingress by individuals of the invading population, a more subtle “invasion” may occur without significant motion of invading individuals if the population dynamics in a predator prey scenario has an “excitable” character. Here, “excitable” means that a local equilibrium

J. Brindley; V. H. Biktashev; M. A. Tsyganov

2005-01-01

421

Range of Excited Electrons in Metals  

Microsoft Academic Search

The energy of interaction of a single excited electron with the sea of conduction electrons in a metal has been calculated by a self-energy approach. The imaginary part of the self-energy of the excited electron can be interpreted in terms of a total rate of real collisions with the sea of conduction electrons. By weighting the differential scattering rate by

John J. Quinn

1962-01-01

422

The Excited State Spectrum of QCD  

SciTech Connect

The determination of the highly excited state spectrum of baryons within QCD is a major theoretical and experimental challenge. I will present recent results from lattice QCD that give some indications on the structure of these highly excited states, and outline on-going and future work needed for a full determination of the spectrum, including strong decays.

Robert Edwards

2010-08-01

423

Search for Excited States of 3HE.  

National Technical Information Service (NTIS)

A search was conducted for virtual excited states of 3He by inelastic electron scattering at E = 200 MeV and theta = 60 degrees. No evidence for narrow states excited with cross section greater than 3 x 10 to the -33rd power sq cm/sr was found for excitat...

R. F. Frosch H. Crannell J. S. McCarthy R. E. Rand R. S. Safrata

1966-01-01

424

Nonlinear parameter estimation of excitation systems  

Microsoft Academic Search

This paper details the nonlinear parameter estimation process of an IEEE AC1A type exciter using time-domain system identification techniques. This paper discusses nonlinear parameter estimation techniques, systematic and random noise mitigation strategies, and system validation. This study establishes a strong basis for excitation system parameter estimation

Rajeev Bhaskar; M. L. Crow; E. Ludwig; Kelvin T. Erickson; Kirit S. Shah

2000-01-01

425

Wave propagation in heterogeneous excitable media  

Microsoft Academic Search

Heterogeneities deeply affect pulse dynamics in excitable media. In one dimension, spatially periodic variation of the excitation threshold leads to a characteristic dependence of the propagation speed on the modulation period d with a maximum at a certain optimal value dopt. The maximum speed may be larger than the pulse velocity in an effective homogeneous medium. In two dimensions, the

I. Schebesch; H. Engel

1998-01-01

426

Coulomb Excitation of exp 226 Ra.  

National Technical Information Service (NTIS)

The isotope exp 226 Ra was studied by multiple Coulomb excitation with a 135 MeV e.g. 150 MeV exp 32 S-beam and with a 243 MeV exp 58 Ni beam. Using particle gamma coincidences the gamma decay of the levels populated at the Coulomb excitation can be obser...

R. Zimmermann

1980-01-01

427

Flashlamp-excited organic dye lasers  

Microsoft Academic Search

The flashlamp-excited dye laser is presently the only type of laser capable of tunable emission throughout most of the visible spectrum. Gain and power output of the device are comparable to solid-state systems although the laser performance is hindered by thermal effects, produced by spatially nonuniform excitation of the dye, and optical losses associated with the molecular triplet state. In

BENJAMIN B. SNAVELY

1969-01-01

428

Optical Excitation of MOS Interface States.  

National Technical Information Service (NTIS)

MOS interface states have been studied in n-type samples by infrared optical excitation. Infrared light in the wavelength range 5 to 15 micrometers was used to excite only shallow states near the conduction band edge. Thermal background radiation was excl...

M. Schulz K. Blumenstock

1980-01-01

429

Routine determination of flumequine in kidney tissue of pig using automated liquid chromatography  

Microsoft Academic Search

A high-performance liquid chromatographic assay is described as a routine analytical method for the determination of flumequine (FLU) and its hydroxylated metabolite (OH-FLU) in pig kidney tissue. Kidney samples (2 g) containing FLU and OH-FLU were extracted by liquid-liquid extraction with ethyl acetate (10 ml). Analytical separations were performed by reversed-phase HPLC with fluorometric detection at 252 nm excitation and

J. Guyonnet; M. Pacaud; M. Richard; A. Doisi; F. Spavone; Ph. Hellings

1996-01-01

430

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

ERIC Educational Resources Information Center

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

Courtois, Matthieu; Guirao, Boris; Fort, Emmanuel

2008-01-01

431

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

ERIC Educational Resources Information Center

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

Courtois, Matthieu; Guirao, Boris; Fort, Emmanuel

2008-01-01

432

Supersolid structure and excitation spectrum of soft-core bosons in three dimensions  

NASA Astrophysics Data System (ADS)

By means of a mean-field method, we have studied the zero-temperature structure and excitation spectrum of a three-dimensional soft-core bosonic system for a value of the interaction strength that favors a crystal structure made of atomic nanoclusters arranged with fcc ordering. In addition to the longitudinal and transverse phonon branches expected for a normal crystal, the excitation spectrum shows a soft mode related to the breaking of gauge symmetry, which signals a partial superfluid character of the solid. Additional evidence of supersolidity is provided by the calculation of the superfluid fraction, which shows a first-order drop, from 1 to 0.4, at the liquid-supersolid transition and a monotonic decrease as the interaction strength parameter is increased. The conditions for the coexistence of the supersolid with the homogeneous superfluid are discussed, and the surface tension of a representative solid-liquid interface is calculated.

Ancilotto, Francesco; Rossi, Maurizio; Toigo, Flavio

2013-09-01

433

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.

Kessler, James H.; Galvan, Patricia M.

2007-01-01

434

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

435

Liquidity and Financial Crises  

Microsoft Academic Search

With money liquidity, transaction liquidity, funding liquidity and their interactions, this article analyzes the innovation of the subprime mortgage crisis and its transformation into the financial crisis. The findings show that as in other historical financial crises the overall liquidity meltdown is the direct cause. The default in subprime mortgage is just the fuse. Typically, as the money policy is

Chen Xiaoyan; Wei Yi; Xu Qin

2009-01-01

436

Endogenous Systemic Liquidity Risk  

Microsoft Academic Search

Traditionally, aggregate liquidity shocks are modelled as exogenous events. Extending our previous work (Cao & Illing, 2008), this paper analyses the adequate policy response to endogenous systemic liquidity risk. We analyse the feedback between lender of last resort policy and incentives of private banks, determining the aggregate amount of liquidity available. We show that imposing minimum liquidity standards for banks

Jin Cao; Gerhard Illing

2009-01-01

437

Endogenous Systemic Liquidity Risk  

Microsoft Academic Search

Traditionally, aggregate liquidity shocks are modelled as exogenous events. Extending our previous work (Cao & Illing, 2007), this paper analyses the adequate policy response to endogenous systemic liquidity risk. We analyse the feedback between lender of last resort policy and incentives of private banks, determining the aggregate amount of liquidity available. We show that imposing minimum liquidity standards for banks

Jin Cao; Gerhard Illing

2008-01-01

438

Liquid Wall Chambers  

Microsoft Academic Search

The key feature of liquid wall chambers is the use of a renewable liquid layer to protect chamber structures from target emissions. Two primary options have been proposed and studied: wetted wall chambers and thick liquid wall (TLW) chambers. With wetted wall designs, a thin layer of liquid shields the structural first wall from short ranged target emissions (x-rays, ions

2011-01-01

439

Liquidity and capital structure  

Microsoft Academic Search

We examine the relation between equity market liquidity and capital structure. We find that firms with more liquid equity have lower leverage and prefer equity financing when raising capital. For example, after sorting firms into size quintiles and then into liquidity quintiles, the average debt-to-asset ratio of the most liquid quintiles is about 38% while the average for the least

Marc L. Lipson; Sandra Mortal

2009-01-01

440

Theoretical model of liquid metals  

SciTech Connect

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

Kerley, G.I.

1981-01-01

441

M1 excitation scheme in deformed nuclei  

NASA Astrophysics Data System (ADS)

We present the M1 excitation scheme in even-even deformed nuclei from the sum-rule viewpoint based on the Nilsson+BCS approach. The sum-rule states are introduced for the Scissors, spin and spin-flip modes. The functional form of the B(M1) sum rule of the Scissors mode is obtained, and its actual value is shown to be 4~6(?N2). The spin excitation B(M1) is 10~15(?N2) including the spin-flip transitions. The total B(M1) is 15~20(?N2). The effect of the SD and SDG pair truncation is studied to test IBM-2 for M1 excitations. The SDG truncation reproduces very well the calculation without truncation. The SD truncation reproduces the orbital excitation, whereas yields some deviations for the spin excitation.

Otsuka, Takaharu; Morrison, Iain

1991-10-01

442

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.

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

2006-01-01

443

Nuclear excitations and reaction mechanisms  

SciTech Connect

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

Fallieros, S.; Levin, F.S.

1990-08-01

444

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

2006-06-06

445

Increasing average power in medical ultrasonic endoscope imaging system by coded excitation  

NASA Astrophysics Data System (ADS)

Medical ultrasonic endoscope is the combination of electronic endoscope and ultrasonic sensor technology. Ultrasonic endoscope sends the ultrasonic probe into coelom through biopsy channel of electronic endoscope and rotates it by a micro pre-motor, which requires that the length of ultrasonic probe is no more than 14mm and the diameter is no more than 2.2mm. As a result, the ultrasonic excitation power is very low and it is difficult to obtain a sharp image. In order to increase the energy and SNR of ultrasonic signal, we introduce coded excitation into the ultrasonic imaging system, which is widely used in radar system. Coded excitation uses a long coded pulse to drive ultrasonic transducer, which can increase the average transmitting power accordingly. In this paper, in order to avoid the overlapping between adjacent echo, we used a four-figure Barker code to drive the ultrasonic transducer, which is modulated at the operating frequency of transducer to improve the emission efficiency. The implementation of coded excitation is closely associated with the transient operating characteristic of ultrasonic transducer. In this paper, the transient operating characteristic of ultrasonic transducer excited by a shock pulse ?(t) is firstly analyzed, and then the exciting pulse generated by special ultrasonic transmitting circuit composing of MD1211 and TC6320. In the final part of the paper, we designed an experiment to validate the coded excitation with transducer operating at 5MHz and a glass filled with ultrasonic coupling liquid as the object. Driven by a FPGA, the ultrasonic transmitting circuit output a four-figure Barker excitation pulse modulated at 5MHz, +/-20 voltage and is consistent with the transient operating characteristic of ultrasonic transducer after matched by matching circuit. The reflected echo from glass possesses coded character, which is identical with the simulating result by Matlab. Furthermore, the signal's amplitude is higher.

Chen, Xiaodong; Zhou, Hao; Wen, Shijie; Yu, Daoyin

2008-12-01

446

Vanishing N=20 Shell Gap: Study of Excited States in {sup 27,28}Ne  

SciTech Connect

This Letter reports on the {sup 1}H({sup 28}Ne,{sup 28}Ne) and {sup 1}H({sup 28}Ne,{sup 27}Ne) reactions studied at intermediate energy using a liquid hydrogen target. From the cross section populating the first 2{sup +} excited state of {sup 28}Ne, and using the previously determined B(E2) value, the neutron quadrupole transition matrix element has been calculated to be M{sub n}=13.8{+-}3.7 fm{sup 2}. In the neutron knockout reaction, two low-lying excited states were populated in {sup 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 {sup 27,28}Ne nuclei caused by a vanishing N=20 shell gap at Z=10.

Dombradi, Zs.; Fueloep, Zs. [Institute of Nuclear Research of the Hungarian Academy of Sciences, P.O. Box 51, Debrecen, H-4001 (Hungary); Elekes, Z. [Institute of Nuclear Research of the Hungarian Academy of Sciences, P.O. Box 51, Debrecen, H-4001 (Hungary); Institute of Physical and Chemical Research, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Saito, A.; Baba, H.; Demichi, K.; Gomi, T.; Hasegawa, H.; Kanno, S.; Kawai, S.; Kurita, K.; Matsuyama, Y.; Sakai, H.K.; Takeshita, E.; Togano, Y.; Yamada, K. [Rikkyo University, 3 Nishi-Ikebukuro, Toshima, Tokyo 171 (Japan); Aoi, N.; Ishihara, M.; Kishida, T.; Kubo, T. [Institute of Physical and Chemical Research, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan)] (and others)

2006-05-12

447

Calculation of highly excited vibrational energy levels of CH3CN molecule by non-linear quantum theory  

Microsoft Academic Search

A three-parameter nonlinear dynamical model, i.e., the quantized discrete self-trapping equation, was used to calculate the highly excited CH stretching vibrational energy levels of liquid phase CH3CN molecule in the electronic ground state up to n=7. The calculated results show that the experimental energy levels can be well described by the model.

Zhu Jun; Gou Qing-quan

1999-01-01

448

Vaporization of sediments with a pulsed transverse excitation at atmospheric pressure (TEA) CO2 laser system  

Microsoft Academic Search

A transverse excitation at atmospheric pressure (TEA) pulsed CO2 laser equipped with an adjunct called a Lasertrace was used to generate vapor and\\/or particulates from sediment samples. The material thus obtained can be transferred to analytical systems for analysis making possible the analysis of solids by techniques previously suitable only for liquids or gases. Approximately one milligram of vapor and\\/or

N. R. Smyrl; H. G. King Jr.

1981-01-01

449

Influence of excitation frequency on slosh-induced impact pressures of liquefied natural gas tanks  

Microsoft Academic Search

Liquid sloshing phenomena in No. 2 tank of 140 km3 liquefied natural gas (LNG) carriers have been studied numerically and experimentally. The scale of the model tank was selected\\u000a as 1\\/55.9. Roll and pitch motions were tested. For measuring impact pressures, seventeen pressure sensors were installed on\\u000a the tank model. A large number of excitation frequencies and filling heights were

Zhong-hua Cai; De-yu Wang; Zhe Li

2011-01-01

450

Luminescence of gadolinium gallium garnet epitaxial films under excitation by synchrotron radiation  

NASA Astrophysics Data System (ADS)

The luminescence excited by synchrotron radiation in gadolinium gallium garnet single-crystal films grown by liquid-phase epitaxy from lead-and bismuth-containing solution melts on Gd3Ga5O12 substrates is investigated. It is shown that the luminescence intensity in the visible range of the spectrum depends on the type and concentration of impurity ions passing from the solvent into the film.

Randoshkin, V. V.; Alparov, R. M.; Vasil'Eva, N. V.; Kolobanov, V. N.; Mikha?lin, V. V.; Petrovnin, N. N.; Spasski?, D. A.; Sysoev, N. N.

2006-11-01

451

Liquid Crystal Response to Surface-Plasmon-Induced Electric Fields  

NASA Astrophysics Data System (ADS)

We demonstrate the effect that localized surface plasmon resonance (LSPR) from gold nanoparticles (AuNPs) has on the director of the nematic liquid crystal 4-Cyano-4'-pentylbiphenyl (5CB). The presence of LSPR of the AuNPs was confirmed using metal enhanced fluorescence of a red dye. Using two light sources, a white light with crossed polarizers to observe the birefringence of the liquid crystal and a 510-550nm light to excite the LSPR, we observe re-orientation of the director of aligned liquid crystal molecules when the AuNPs are excited with light matching the LPSR absorption band. This response is observed to be temperature dependent and only seen to occur within 1 degree Celsius of the phase transition from nematic to isotropic phase.

Nuno, Zachary; Hirst, Linda; Ghosh, Sayantani

2012-11-01

452

Liquid helium in disorder and boson localization  

NASA Astrophysics Data System (ADS)

Neutron scattering measurements of the excitations of liquid ^4He confined in three porous media focusing on temperatures around the superfluid-normal fluid critical temperature Tc are presented and discussed. The three porous media are Vycor (Tc= 2.05 K at SVP), 44 å pore diameter gelsil (Tc= 1.92 K at SVP) and 25 å pore diameter gelsil (Tc 1.0 K at SVP) ^[1,2]. In all these media, liquid ^4He supports well-defined phonon-roton excitations above Tc, in the "normal" phase (up T?= 2.17 K at SVP). Since well-defined excitations are associated with Bose-Einstein condensation (BEC), this suggests that there is BEC in the "normal" phase. Also, since there is no superflow, this BEC is apparently localized in the media separated by regions of normal fluid. In this picture, the superfluid-normal transition in disorder is associated with an extended-localized BEC crossover with localized BEC remaining above Tc ^[3]. ^[1]F. Albergamo et al., Phys. Rev. B 69, 014514 (2004) ^[2]J. V. Pearce et al., Phys. Rev. Lett. 93, 145303 (2004)) ^[3]H. R. Glyde et al., Phys. Rev. Lett. 84, 2646 (2000)

Albergamo, Francesco; Pearce, Jonathan; Glyde, Henry; Daughton, David; Mulders, Norbert; Bossy, Jacques; Schober, Helmut

2005-03-01

453

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

454

Incommensurate spin excitations stabilized multiferroic phase in CuO  

NASA Astrophysics Data System (ADS)

Cupric oxide is a unique magnetoferroelectrics with transition temperature way above the boiling point of liquid nitrogen. However, the mechanism of high Tc multiferroicity in CuO is still puzzling. In this paper, we clarify the mechanism of high Tc multiferroicity in CuO using combined first-principles calculations and an effective Hamiltonian model. We find that CuO contains two magnetic sublattices, with strong intra-sublattice interactions and weakly frustrated inter-sublattice interactions, which might be one of the main reasons that the compound has a high ordering temperature. The weak spin frustration leads to incommensurate spin excitations that dramatically enhances the entropy of the mutliferroic phase, and eventually stabilize the mutliferroic phase in CuO.

He, Lixin

2012-02-01

455

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

456

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

457

Coulomb excitation of radioactive 20, 21Na  

NASA Astrophysics Data System (ADS)

The low-energy structures of the radioactive nuclei 20, 21Na have been examined using Coulomb excitation at the TRIUMF-ISAC radioactive ion beam facility. Beams of ˜ 5×106 ions/s were accelerated to 1.7MeV/A and Coulomb excited in a 0.5mg/cm^2 natTi target. Two TIGRESS HPGe clover detectors perpendicular to the beam axis were used for ? -ray detection, while scattered nuclei were observed by the Si detector BAMBINO. For 21Na , Coulomb excitation from the 3/2+ ground state to the first excited 5/2+ state was observed, while for 20Na , Coulomb excitation was observed from the 2+ ground state to the first excited 3+ and 4+ states. For both beams, B ( ? L) values were determined using the 2+ rightarrow 0+ de-excitation in 48Ti as a reference. The resulting B( E2) ? value for 21Na is 137±9 e^2fm^4, while the resulting B( ? L) ? values for 20Na are 55±6 e^2fm^4 for the 3+ rightarrow 2+ , 35.7±5.7 e^2 fm^4 for the 4+ rightarrow 2+ , and 0.154±0.030 ?_ N^2 for the 4+ rightarrow 3+ transitions. This analysis significantly improves the measurement of the 21Na B( E2) value, and provides the first experimental determination of B( ? L) values for the proton dripline nucleus 20Na .-1

Schumaker, M. A.; Cline, D.; Hackman, G.; Pearson, C.; Svensson, C. E.; Wu, C. Y.; Andreyev, A.; Austin, R. A. E.; Ball, G. C.; Bandyopadhyay, D.; Becker, J. A.; Boston, A. J.; Boston, H. C.; Buchmann, L.; Churchman, R.; Cifarelli, F.; Cooper, R. J.; Cross, D. S.; Dashdorj, D.; Demand, G. A.; Dimmock, M. R.; Drake, T. E.; Finlay, P.; Gallant, A. T.; Garrett, P. E.; Green, K. L.; Grint, A. N.; Grinyer, G. F.; Harkness, L. J.; Hayes, A. B.; Kanungo, R.; Lisetskiy, A. F.; Leach, K. G.; Lee, G.; Maharaj, R.; Martin, J.-P.; Moisan, F.; Morton, A. C.; Mythili, S.; Nelson, L.; Newman, O.; Nolan, P. J.; Orce, J. N.; Padilla-Rodal, E.; Phillips, A. A.; Porter-Peden, M.; Ressler, J. J.; Roy, R.; Ruiz, C.; Sarazin, F.; Scraggs, D. P.; Waddington, J. C.; Wan, J. M.; Whitbeck, A.; Williams, S. J.; Wong, J.

2009-12-01

458

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

459

First Evidence of Double Spin Isospin Excitation  

NASA Astrophysics Data System (ADS)

To study double spin-isospin responses in view of the ??0? decays, double charge-exchange nuclear reactions have measured at RCNP. We have succeeded to measure the double charge exchange reaction by means of heavy ion reaction. From these experiments, we conclude that the (11B,11Li) reaction at 70 MeV/nucleon is a go