WorldWideScience

Sample records for reactant internal excitations

  1. International Meeting: Excited QCD 2014

    CERN Document Server

    Giacosa, Francesco; Malek, Magdalena; Marinkovic, Marina; Parganlija, Denis

    2014-01-01

    Excited QCD 2014 will take place on the beautiful Bjelasnica mountain located in the vicinity of the Bosnian capital Sarajevo. Bjelasnica was a venue of the XIV Winter Olympic Games and it is situated only 30 kilometers from Sarajevo International Airport. The workshop program will start on February 2 and finish on February 8, 2014, with scientific lectures taking place from February 3 to 7. Workshop participants will be accomodated in Hotel Marsal, only couple of minutes by foot from the Olympic ski slopes. ABOUT THE WORKSHOP This edition is the sixth in a series of workshops that were previously organised in Poland, Slovakia, France and Portugal. Following the succesful meeting in 2013, the Workshop is returning to Sarajevo Olympic mountains in 2014, exactly thirty years after the Games. The workshop covers diverse aspects of QCD: (i) QCD at low energies: excited hadrons, glueballs, multiquarks. (ii) QCD at high temperatures and large densities: heavy-ion collisions, jets, diffraction, hadronisation, quark-...

  2. Electron collisions and internal excitation in stored molecular ion beams

    International Nuclear Information System (INIS)

    Buhr, H.

    2006-01-01

    In storage ring experiments the role, which the initial internal excitation of a molecular ion can play in electron collisions, and the effect of these collisions on the internal excitation are investigated. Dissociative recombination (DR) and inelastic and super-elastic collisions are studied in the system of He + 2 . The DR rate coefficient at low energies depends strongly on the initial vibrational excitation in this system. Therefore changes in the DR rate coefficient are a very sensitive probe for changes in the vibrational excitation in He + 2 , which is used to investigate the effects of collisions with electrons and residual gas species. The low-energy DR of HD + is rich with resonances from the indirect DR process, when certain initial rotational levels in the molecular ion are coupled to levels in neutral Rydberg states lying below the ion state. Using new procedures for high-resolution electron-ion collision spectroscopy developed here, these resonances in the DR cross section can be measured with high energy sensitivity. This allows a detailed comparison with results of a MQDT calculation in an effort to assign some or all of the resonances to certain intermediate Rydberg levels. (orig.)

  3. Electron collisions and internal excitation in stored molecular ion beams

    Energy Technology Data Exchange (ETDEWEB)

    Buhr, H.

    2006-07-26

    In storage ring experiments the role, which the initial internal excitation of a molecular ion can play in electron collisions, and the effect of these collisions on the internal excitation are investigated. Dissociative recombination (DR) and inelastic and super-elastic collisions are studied in the system of He{sup +}{sub 2}. The DR rate coefficient at low energies depends strongly on the initial vibrational excitation in this system. Therefore changes in the DR rate coefficient are a very sensitive probe for changes in the vibrational excitation in He{sup +}{sub 2}, which is used to investigate the effects of collisions with electrons and residual gas species. The low-energy DR of HD{sup +} is rich with resonances from the indirect DR process, when certain initial rotational levels in the molecular ion are coupled to levels in neutral Rydberg states lying below the ion state. Using new procedures for high-resolution electron-ion collision spectroscopy developed here, these resonances in the DR cross section can be measured with high energy sensitivity. This allows a detailed comparison with results of a MQDT calculation in an effort to assign some or all of the resonances to certain intermediate Rydberg levels. (orig.)

  4. Equalization equations in reactant resolution

    Indian Academy of Sciences (India)

    Unknown

    given partitioning of the system in physical or functional space. The most frequently ... Then, the inter-reactant equilibrium is considered. The ... Global equilibrium. Even though the chemical potential in the case of global equilibrium is equalized by definition (see (1)), we repeat here the proof, for the current needs, using.

  5. Dynamic response of a riser under excitation of internal waves

    Science.gov (United States)

    Lou, Min; Yu, Chenglong; Chen, Peng

    2015-12-01

    In this paper, the dynamic response of a marine riser under excitation of internal waves is studied. With the linear approximation, the governing equation of internal waves is given. Based on the rigid-lid boundary condition assumption, the equation is solved by Thompson-Haskell method. Thus the velocity field of internal waves is obtained by the continuity equation. Combined with the modified Morison formula, using finite element method, the motion equation of riser is solved in time domain with Newmark-β method. The computation programs are compiled to solve the differential equations in time domain. Then we get the numerical results, including riser displacement and transfiguration. It is observed that the internal wave will result in circular shear flow, and the first two modes have a dominant effect on dynamic response of the marine riser. In the high mode, the response diminishes rapidly. In different modes of internal waves, the deformation of riser has different shapes, and the location of maximum displacement shifts. Studies on wave parameters indicate that the wave amplitude plays a considerable role in response displacement of riser, while the wave frequency contributes little. Nevertheless, the internal waves of high wave frequency will lead to a high-frequency oscillation of riser; it possibly gives rise to fatigue crack extension and partial fatigue failure.

  6. Thin film characterization by resonantly excited internal standing waves

    Energy Technology Data Exchange (ETDEWEB)

    Di Fonzio, S [SINCROTRONE TRIESTE, Trieste (Italy)

    1996-09-01

    This contribution describes how a standing wave excited in a thin film can be used for the characterization of the properties of the film. By means of grazing incidence X-ray reflectometry one can deduce the total film thickness. On the other hand in making use of a strong resonance effect in the electric field intensity distribution inside a thin film on a bulk substrate one can learn more about the internal structure of the film. The profile of the internal standing wave is proven by diffraction experiments. The most appropriate non-destructive technique for the subsequent thin film characterization is angularly dependent X-ray fluorescence analysis. The existence of the resonance makes it a powerful tool for the detection of impurities and of ultra-thin maker layers, for which the position can be determined with very high precision (about 1% of the total film thickness). This latter aspect will be discussed here on samples which had a thin Ti marker layer at different positions in a carbon film. Due to the resonance enhancement it was still possible to perform these experiments with a standard laboratory x-ray tube and with standard laboratory tool for marker or impurity detection in thin films.

  7. Excitation of internal kink modes by trapped energetic beam ions

    International Nuclear Information System (INIS)

    Chen, L.; White, R.B.; Rosenbluth, M.N.

    1983-10-01

    Energetic trapped particles are shown to have a destabilizing effect on the internal kink mode in tokamaks. The plasma pressure threshold for the mode is lowered by the particles. The growth rate is near the ideal magnetohydrodynamic value, but the frequency is comparable to the trapped particle precission frequency. A model for the instability cycle gives stability properties, associated particle losses, and neutron emissivity consistent with the fishbone events observed in PDX

  8. International Ultraviolet Explorer satellite observations of seven high-excitation planetary nebulae.

    Science.gov (United States)

    Aller, L H; Keyes, C D

    1980-03-01

    Observations of seven high-excitation planetary nebulae secured with the International Ultraviolet Explorer (IUE) satellite were combined with extensive ground-based data to obtain electron densities, gas kinetic temperatures, and ionic concentrations. We then employed a network of theoretical model nebulae to estimate the factors by which observed ionic concentrations must be multiplied to obtain elemental abundances. Comparison with a large sample of nebulae for which extensive ground-based observations have been obtained shows nitrogen to be markedly enhanced in some of these objects. Possibly most, if not all, high-excitation nebulae evolve from stars that have higher masses than progenitors of nebulae of low-to-moderate excitation.

  9. Modelling of inductively coupled discharges excited by internal coils

    International Nuclear Information System (INIS)

    Lister, G.G.

    1991-01-01

    Modelling of inductively coupled discharges provides a method for computing parameters such as current, electrical conductivity and electromagnetic field strengths which are difficult to measure experimentally. The models reported in the literature to date deal with discharges which are surrounded by an induction coil where the plasma is considered as a one-turn secondary winding of a transformer. Eckert derived expressions for electromagnetic fields and impedance in discharges assuming Bessel function solutions to the wave and electron density equations, while more recently Denneman solved the non-linear problem, including the effects of a radial conductivity profile on the electromagnetic fields in a Ar-Hg discharge. Modelling of an ICD in which the coil is in the centre of the discharge presents an additional difficulty, since the coil does not provide a natural external boundary condition. In this paper, we compare numerical results from the approaches of Eckert and Denneman applied to discharges with internal coils, with a view to identifying relevant parameters applicable to interpretation of experiments. (author) 2 refs., 2 figs., 1 tab

  10. The behavior of exciplex decay processes and interplay of radiationless transition and preliminary reorganization mechanisms of electron transfer in loose and tight pairs of reactants.

    Science.gov (United States)

    Kuzmin, Michael G; Soboleva, Irina V; Dolotova, Elena V

    2007-01-18

    Exciplex emission spectra and rate constants of their decay via internal conversion and intersystem crossing are studied and discussed in terms of conventional radiationless transition approach. Exciplexes of 9-cyanophenanthrene with 1,2,3-trimethoxybenzene and 1,3,5-trimethoxybenzene were studied in heptane, toluene, butyl acetate, dichloromethane, butyronitrile, and acetonitrile. A better description of spectra and rate constants is obtained using 0-0 transition energy and Gauss broadening of vibrational bands rather than the free energy of electron transfer and reorganization energy. The coincidence of parameters describing exciplex emission spectra and dependence of exciplex decay rate constants on energy gap gives the evidence of radiationless quantum transition mechanism rather than thermally activated medium reorganization mechanism of charge recombination in exciplexes and excited charge transfer complexes (contact radical ion pairs) as well as in solvent separated radical ion pairs. Radiationless quantum transition mechanism is shown to provide an appropriate description also for the main features of exergonic excited-state charge separation reactions if fast mutual transformations of loose and tight pairs of reactants are considered. In particular, very fast electron transfer (ET) in tight pairs of reactants with strong electronic coupling of locally excited and charge transfer states can prevent the observation of an inverted region in bimolecular excited-state charge separation even for highly exergonic reactions.

  11. Energy Cascade from Internal Modes in Non-uniformly Stratified Fluid through Excitation of Superharmonic Disturbances

    Science.gov (United States)

    Sutherland, B. R.

    2016-02-01

    It is well established that two-dimensional internal plane waves and modes in uniformly stratified fluid efficiently transfer energy to smaller scale waves and ultimately turbulent mixing through parametric subharmonic instability (PSI). The numerical simulations of MacKinnon & Winters (GRL 2005) predicted PSI should act efficiently to disrupt the internal tide. However, while in situ observations showed the presence of PSI, it was not found to be appreciable. One reason for the discrepancy between simulations and observations is that the former examined an internal mode in uniformly stratified fluid whereas, in reality, the internal tide exists in non-uniform stratification and is manifest as sinusoidal oscillations of the thermocline. Through theory supported by numerical simulations, it is shown that internal modes in non-uniform stratification immediately excite superharmonics, not subharmonic disturbances. These have double the horizontal wavenumber and double the frequency of the parent mode and hence move with the same horizontal phase speed of the parent mode. As the disturbances grow in amplitude, however, they interact with the parent mode generating small-scale vertically propagating internal waves within the strongly stratified layer. The occurrence of PSI over very long times can occur, as in the simulations of Hazewinkel and Winters (JPO 2011). However, a comprehensive understanding of the energy cascade from the internal tide to small scales must consider the evolution of excited superharmonic disturbances.

  12. Can Internal Conversion BE Controlled by Mode-Specific Vibrational Excitation in Polyatomic Molecules

    Science.gov (United States)

    Portnov, Alexander; Epshtein, Michael; Bar, Ilana

    2017-06-01

    Nonadiabatic processes, dominated by dynamic passage of reactive fluxes through conical intersections (CIs) are considered to be appealing means for manipulating reaction paths. One approach that is considered to be effective in controlling the course of dissociation processes is the selective excitation of vibrational modes containing a considerable component of motion. Here, we have chosen to study the predissociation of the model test molecule, methylamine and its deuterated isotopologues, excited to well-characterized quantum states on the first excited electronic state, S_{1}, by following the N-H(D) bond fission dynamics through sensitive H(D) photofragment probing. The branching ratios between slow and fast H(D) photofragments, the internal energies of their counter radical photofragments and the anisotropy parameters for fast H photofragments, confirm correlated anomalies for predissociation initiated from specific rovibronic states, reflecting the existence of a dynamic resonance in each molecule. This resonance strongly depends on the energy of the initially excited rovibronic states, the evolving vibrational mode on the repulsive S_{1} part during N-H(D) bond elongation, and the manipulated passage through the CI that leads to radicals excited with C-N-H(D) bending and preferential perpendicular bond breaking, relative to the photolyzing laser polarization, in molecules containing the NH_{2} group. The indicated resonance plays an important role in the bifurcation dynamics at the CI and can be foreseen to exist in other photoinitiated processes and to control their outcome.

  13. Vibrational response of a rectangular duct of finite length excited by a turbulent internal flow

    Science.gov (United States)

    David, Antoine; Hugues, Florian; Dauchez, Nicolas; Perrey-Debain, Emmanuel

    2018-05-01

    Gas transport ductwork in industrial plants or air conditioning networks can be subject to vibrations induced by the internal flow. Most studies in this matter have been carried out on circular ducts. This paper focuses specifically on the vibratory response of a rectangular duct of finite length excited by an internal turbulent flow. A semi-analytical model taking into account the modal response of the structure due to both aerodynamic and acoustic contributions is derived. The aerodynamic component of the excitation is applied on the basis of Corcos model where the power spectral density of the wall pressure is determined experimentally. The acoustic component is based on the propagating modes in the duct where the acoustic modal contribution are extracted via cross-spectral densities. The vibrational response is given for a 0.2 × 0.1 × 0.5 m3 duct made of 3 mm steel plates excited by 20 m/s or 30 m/s flows. Comparisons between experimental results and numerical predictions show a good agreement. The competition between acoustic and aerodynamic components is highlighted.

  14. Concluding remarks of international symposium on highly excited states in nuclear reactions

    Energy Technology Data Exchange (ETDEWEB)

    Bernstein, A. M.; Ikegami, H.; Muraoka, M. [eds.

    1980-01-01

    This is the concluding remarks in the international symposium on highly excited states in nuclear reactions. The remarks concentrate on the giant quadrupole states. In the framework of the distorted wave Born approximation (DWB), the differential cross section can be deduced. The relevant transition matrix elements are defined, and the quantities which are measured in inelastic hadron (h, h') reactions are shown. These are used to obtain both neutron and proton transition multipole matrix elements. This is equivalent to make the isospin decomposition of the electromagnetic transition matrix elements. The ratios of the transition matrix elements of neutrons and protons of the lowest 2/sup +/ states in even-even single closed shell nuclei are evaluated and compared with experimental results. For each nucleus, the consistency between various measurements is generally good. The effect of the virtual excitation of giant 2/sup +/ states into the ground and first excited states of even-even nuclei is discussed. The accuracy of (h, h') results can be tested.

  15. Formation of H{sub 2} from internally heated polycyclic aromatic hydrocarbons: Excitation energy dependence

    Energy Technology Data Exchange (ETDEWEB)

    Chen, T., E-mail: tao.chen@fysik.su.se, E-mail: henning@fysik.su.se; Gatchell, M.; Stockett, M. H.; Schmidt, H. T.; Cederquist, H.; Zettergren, H., E-mail: tao.chen@fysik.su.se, E-mail: henning@fysik.su.se [Department of Physics, Stockholm University, S-106 91 Stockholm (Sweden); Delaunay, R.; Rousseau, P.; Adoui, L. [CIMAP, UMR 6252, CEA/CNRS/ENSICAEN/Université de Caen Basse-Normandie, bd Henri Becquerel, BP 5133, F-14070 Caen cedex 05 (France); Université de Caen Basse-Normandie, Esplanade de la Paix, F-14032 Caen (France); Domaracka, A.; Huber, B. A. [CIMAP, UMR 6252, CEA/CNRS/ENSICAEN/Université de Caen Basse-Normandie, bd Henri Becquerel, BP 5133, F-14070 Caen cedex 05 (France); Micelotta, E. R. [Université Paris Sud, Institut d’Astrophysique Spatiale, UMR 8617, 91405 Orsay (France); Tielens, A. G. G. M. [Leiden Observatory, Leiden University, P.O. Box 9513, 2300 RA Leiden (Netherlands)

    2015-04-14

    We have investigated the effectiveness of molecular hydrogen (H{sub 2}) formation from Polycyclic Aromatic Hydrocarbons (PAHs) which are internally heated by collisions with keV ions. The present and earlier experimental results are analyzed in view of molecular structure calculations and a simple collision model. We estimate that H{sub 2} formation becomes important for internal PAH temperatures exceeding about 2200 K, regardless of the PAH size and the excitation agent. This suggests that keV ions may effectively induce such reactions, while they are unlikely due to, e.g., absorption of single photons with energies below the Lyman limit. The present analysis also suggests that H{sub 2} emission is correlated with multi-fragmentation processes, which means that the [PAH-2H]{sup +} peak intensities in the mass spectra may not be used for estimating H{sub 2}-formation rates.

  16. Parametric instability and wave turbulence driven by tidal excitation of internal waves

    Science.gov (United States)

    Le Reun, Thomas; Favier, Benjamin; Le Bars, Michael

    2018-04-01

    We investigate the stability of stratified fluid layers undergoing homogeneous and periodic tidal deformation. We first introduce a local model which allows to study velocity and buoyancy fluctuations in a Lagrangian domain periodically stretched and sheared by the tidal base flow. While keeping the key physical ingredients only, such a model is efficient to simulate planetary regimes where tidal amplitudes and dissipation are small. With this model, we prove that tidal flows are able to drive parametric subharmonic resonances of internal waves, in a way reminiscent of the elliptical instability in rotating fluids. The growth rates computed via Direct Numerical Simulations (DNS) are in very good agreement with WKB analysis and Floquet theory. We also investigate the turbulence driven by this instability mechanism. With spatio-temporal analysis, we show that it is a weak internal wave turbulence occurring at small Froude and buoyancy Reynolds numbers. When the gap between the excitation and the Brunt-V\\"ais\\"al\\"a frequencies is increased, the frequency spectrum of this wave turbulence displays a -2 power law reminiscent of the high-frequency branch of the Garett and Munk spectrum (Garrett & Munk 1979) which has been measured in the oceans. In addition, we find that the mixing efficiency is altered compared to what is computed in the context of DNS of stratified turbulence excited at small Froude and large buoyancy Reynolds numbers and is consistent with a superposition of waves.

  17. Boltzmann rovibrational collisional coarse-grained model for internal energy excitation and dissociation in hypersonic flows.

    Science.gov (United States)

    Munafò, A; Panesi, M; Magin, T E

    2014-02-01

    A Boltzmann rovibrational collisional coarse-grained model is proposed to reduce a detailed kinetic mechanism database developed at NASA Ames Research Center for internal energy transfer and dissociation in N(2)-N interactions. The coarse-grained model is constructed by lumping the rovibrational energy levels of the N(2) molecule into energy bins. The population of the levels within each bin is assumed to follow a Boltzmann distribution at the local translational temperature. Excitation and dissociation rate coefficients for the energy bins are obtained by averaging the elementary rate coefficients. The energy bins are treated as separate species, thus allowing for non-Boltzmann distributions of their populations. The proposed coarse-grained model is applied to the study of nonequilibrium flows behind normal shock waves and within converging-diverging nozzles. In both cases, the flow is assumed inviscid and steady. Computational results are compared with those obtained by direct solution of the master equation for the rovibrational collisional model and a more conventional multitemperature model. It is found that the proposed coarse-grained model is able to accurately resolve the nonequilibrium dynamics of internal energy excitation and dissociation-recombination processes with only 20 energy bins. Furthermore, the proposed coarse-grained model provides a superior description of the nonequilibrium phenomena occurring in shock heated and nozzle flows when compared with the conventional multitemperature models.

  18. Resonant Tidal Excitation of Internal Waves in the Earth's Fluid Core

    Science.gov (United States)

    Tyler, Robert H.; Kuang, Weijia

    2014-01-01

    It has long been speculated that there is a stably stratified layer below the core-mantle boundary, and two recent studies have improved the constraints on the parameters describing this stratification. Here we consider the dynamical implications of this layer using a simplified model. We first show that the stratification in this surface layer has sensitive control over the rate at which tidal energy is transferred to the core. We then show that when the stratification parameters from the recent studies are used in this model, a resonant configuration arrives whereby tidal forces perform elevated rates of work in exciting core flow. Specifically, the internal wave speed derived from the two independent studies (150 and 155 m/s) are in remarkable agreement with the speed (152 m/s) required for excitation of the primary normal mode of oscillation as calculated from full solutions of the Laplace Tidal Equations applied to a reduced-gravity idealized model representing the stratified layer. In evaluating this agreement it is noteworthy that the idealized model assumed may be regarded as the most reduced representation of the stratified dynamics of the layer, in that there are no non-essential dynamical terms in the governing equations assumed. While it is certainly possible that a more realistic treatment may require additional dynamical terms or coupling, it is also clear that this reduced representation includes no freedom for coercing the correlation described. This suggests that one must accept either (1) that tidal forces resonantly excite core flow and this is predicted by a simple model or (2) that either the independent estimates or the dynamical model does not accurately portray the core surface layer and there has simply been an unlikely coincidence between three estimates of a stratification parameter which would otherwise have a broad plausible range.

  19. K-scrambling in a near-symmetric top molecule containing an excited noncoaxial internal rotor

    International Nuclear Information System (INIS)

    Ortigoso, Juan; Hougen, Jon T.

    2000-01-01

    Classical trajectories on rotational energy surfaces and coherent-state quantum projections have been used to study an asymmetric-top molecule containing a freely rotating internal symmetric top whose symmetry axis is not coincident with a principal axis of the molecule. Stationary points on the rotational energy surface, which strongly influence the trajectories, increase in number from two to four to six as J/n increases from zero to infinity (where J is the total and n is the free-internal-rotor angular momentum). For some J/n values trajectories can arise that sample a large fraction of K values (where K is the z-axis projection of J), corresponding in quantum wave functions to extensive K mixing in the symmetric-top basis set |J,K>. When such mixing cannot be made small for any choice of z axis, we call it K scrambling. For typical values of the torsion-rotation coupling parameter ρ, rotational eigenfunctions for a given J and torsional state turn out to be quite different from eigenfunctions for the same J in some other torsional state. Nonzero rotational overlap integrals are then distributed among many rotational functions for each (n,n ' ) pair, which may, in turn, contribute to internal rotation enhancement of intramolecular vibrational energy redistribution. We have also examined near-free-rotor levels of our test molecule acetaldehyde, which arise for excitation of ten or more quanta of methyl group torsion, and find that barrier effects do not change the qualitative picture obtained from the free-rotor treatment. (c) 2000 American Institute of Physics

  20. Principal component analysis acceleration of rovibrational coarse-grain models for internal energy excitation and dissociation

    Science.gov (United States)

    Bellemans, Aurélie; Parente, Alessandro; Magin, Thierry

    2018-04-01

    The present work introduces a novel approach for obtaining reduced chemistry representations of large kinetic mechanisms in strong non-equilibrium conditions. The need for accurate reduced-order models arises from compression of large ab initio quantum chemistry databases for their use in fluid codes. The method presented in this paper builds on existing physics-based strategies and proposes a new approach based on the combination of a simple coarse grain model with Principal Component Analysis (PCA). The internal energy levels of the chemical species are regrouped in distinct energy groups with a uniform lumping technique. Following the philosophy of machine learning, PCA is applied on the training data provided by the coarse grain model to find an optimally reduced representation of the full kinetic mechanism. Compared to recently published complex lumping strategies, no expert judgment is required before the application of PCA. In this work, we will demonstrate the benefits of the combined approach, stressing its simplicity, reliability, and accuracy. The technique is demonstrated by reducing the complex quantum N2(g+1Σ) -N(S4u ) database for studying molecular dissociation and excitation in strong non-equilibrium. Starting from detailed kinetics, an accurate reduced model is developed and used to study non-equilibrium properties of the N2(g+1Σ) -N(S4u ) system in shock relaxation simulations.

  1. Physiology of excitable membranes: proceedings of the 28th International Congress of Physiological Sciences, Budapest, 1980

    National Research Council Canada - National Science Library

    Salánki, J; Meves, H

    1981-01-01

    ... - - - - - - - - - - - - - - - - - - - - - Regulatory Functions of the CNS. Principles of Motion and Organization Regulatory Functions of the CNS. Subsystems Physiology of Non-excitable Cells Physiology...

  2. Ion Internal Excitation and Co++ 2 Reactivity: Effect On The Titan, Mars and Venus Ionospheric Chemistry

    Science.gov (United States)

    Nicolas, C.; Zabka, J.; Thissen, R.; Dutuit, O.; Alcaraz, C.

    In planetary ionospheres, primary molecular and atomic photoions can be produced with substantial electronic and vibrational internal energy. In some cases, this is known to strongly affect both the rate constants and the branching ratio between the reac- tion products. A previous experimental study (Nicolas et al.) made at the Orsay syn- chrotron radiation facility has shown that many endothermic charge transfer reactions which were not considered in the ionospheric chemistry models of Mars, Venus and Earth have to be included because they are driven by electronic excitation of the parent ions. New measurements on two important reactions for Titan and Mars ionospheres, N+ + CH4 and O+ + CO2, will be presented. Branching ratios between products are very different when the parent atomic ions are prepared in their ground states, N+(3P) and O+(4S), or in their first electronic metastable states N+(1D) and O+(2D or P). 2 As the lifetime of these states are long enough, they survive during the mean time be- tween two collisions in the ionospheric conditions. So, the reactions of these excited states must be included in the ionospheric models. Absolute cross section measurements of the reactivity of stable doubly charged molec- ular ions CO++ and their implications for the Martian ionosphere will also be pre- 2 sented. The molecular dication CO++ production by VUV photoionisation and elec- 2 tron impact in the upper ionosphere of Mars is far from being negligible. However, to determine its concentration, it was necessary to evaluate the major loss channels of these ions. For this purpose, we measured the absolute reaction cross section of the sta- ble dications with CO2, the major neutral species of the Mars ionosphere. CO++ ions 2 were produced either by photoionisation or by electron impact, and a reaction cross section of 45 Å2 with 13CO2 was measured. The reaction leads to charge transfer or to collision induced dissociation. These results were integrated in a model

  3. Conductive polymer layers to limit transfer of fuel reactants to catalysts of fuel cells to reduce reactant crossover

    Science.gov (United States)

    Stanis, Ronald J.; Lambert, Timothy N.

    2016-12-06

    An apparatus of an aspect includes a fuel cell catalyst layer. The fuel cell catalyst layer is operable to catalyze a reaction involving a fuel reactant. A fuel cell gas diffusion layer is coupled with the fuel cell catalyst layer. The fuel cell gas diffusion layer includes a porous electrically conductive material. The porous electrically conductive material is operable to allow the fuel reactant to transfer through the fuel cell gas diffusion layer to reach the fuel cell catalyst layer. The porous electrically conductive material is also operable to conduct electrons associated with the reaction through the fuel cell gas diffusion layer. An electrically conductive polymer material is coupled with the fuel cell gas diffusion layer. The electrically conductive polymer material is operable to limit transfer of the fuel reactant to the fuel cell catalyst layer.

  4. Combustion flame-plasma hybrid reactor systems, and chemical reactant sources

    Science.gov (United States)

    Kong, Peter C

    2013-11-26

    Combustion flame-plasma hybrid reactor systems, chemical reactant sources, and related methods are disclosed. In one embodiment, a combustion flame-plasma hybrid reactor system comprising a reaction chamber, a combustion torch positioned to direct a flame into the reaction chamber, and one or more reactant feed assemblies configured to electrically energize at least one electrically conductive solid reactant structure to form a plasma and feed each electrically conductive solid reactant structure into the plasma to form at least one product is disclosed. In an additional embodiment, a chemical reactant source for a combustion flame-plasma hybrid reactor comprising an elongated electrically conductive reactant structure consisting essentially of at least one chemical reactant is disclosed. In further embodiments, methods of forming a chemical reactant source and methods of chemically converting at least one reactant into at least one product are disclosed.

  5. Kinetics studies following state-selective laser excitation

    International Nuclear Information System (INIS)

    Keto, J.W.

    1994-04-01

    The objective of this contract was the study of state-to-state, electronic energy transfer reactions relevant to the excited state chemistry observed in discharges. We studied deactivation reactions and excitation transfer in collisions of excited states of xenon and krypton atoms with Ar, Kr, Xe and chlorine. The reactant states were excited selectively in two-photon transitions using tunable u.v. and v.u.v. lasers. Excited states produced by the collision were observed by their fluorescence. Reaction rates were measured by observing the time dependent decay of signals from reactant and product channels. In addition we measured interaction potentials of the reactants by laser spectroscopy where the laser induced fluorescence or ionization is measured as a function of laser wavelength (excitation spectra) or by measuring fluorescence spectra at fixed laser frequencies with monochromators. The spectra were obtained in the form of either lineshapes or individual lines from rovibrational transitions of bound states. Our research then required several categories of experiments in order to fully understand a reaction process: 1. High resolution laser spectroscopy of bound molecules or lineshapes of colliding pairs is used to determine potential curves for reactants. 2. Direct measurements of state-to-state reaction rates were measured by studying the time dependent loss of excited reactants and the time dependent formation of products. 3. The energy selectivity of a laser can be used to excite reactants on an excited surface with controlled internuclear configurations. For free states of reactants (as exist in a gas cell) this has been termed laser assisted reactions, while for initially bound states (as chemically bound reactants or dimers formed in supersonic beams) the experiments have been termed photo-fragmentation spectroscopy

  6. Coherent Motion Reveals Non‐Ergodic Nature of Internal Conversion between Excited States

    DEFF Research Database (Denmark)

    Kuhlman, Thomas Scheby; Sølling, Theis I.; Møller, Klaus Braagaard

    2012-01-01

    for smaller molecules. Specifically, we focus on the S2→S1 internal conversion in cyclobutanone, cyclopentanone, and cyclohexanone. By means of time‐resolved mass spectrometry and photoelectron spectroscopy the relative rate of this transition is determined to be 13:2:1. Remarkably, we observe coherent......We found that specific nuclear motion along low‐frequency modes is effective in coupling electronic states and that this motion prevail in some small molecules. Thus, in direct contradiction to what is expected based on the standard models, the internal conversion process can proceed faster...

  7. Synthesis of new thermoelectrics using modulated elemental reactants

    Energy Technology Data Exchange (ETDEWEB)

    Hornbostel, M D; Sellinschegg, H; Johnson, D C

    1997-07-01

    A series of new, metastable ternary crystalline compounds with the skutterudite crystal structure have been synthesized using modulated elemental reactants. The initial reactants are made up of multiple repeats of a {approximately}25 {angstrom} thick unit containing elemental layers of the desired ternary metal, iron and antimony. Low temperature annealing (150 C) results in interdiffusion of the elemental layers to form amorphous reaction intermediates. Annealing these intermediates at temperatures between 200 C and 250 C results in exothermic crystallization of the desired skutterudite crystal structure. Most of the new compounds prepared are only kinetically stable, decomposing exothermically to form thermodynamically more stable mixtures of binary compounds and elements. Low angle x-ray diffraction studies show that the resulting films are exceedingly smooth. These films have an ideal geometry for measuring properties of importance for thermoelectric devices--the Seebeck coefficient and the electrical conductivity. Thermal conductivity can be measured using a modification of the 3{omega} technique of Cahill. Samples can be produced rapidly, allowing for systematic screening and subsequent optimization as a function of composition and doping levels.

  8. Predicting Upscaled Behavior of Aqueous Reactants in Heterogeneous Porous Media

    Science.gov (United States)

    Wright, E. E.; Hansen, S. K.; Bolster, D.; Richter, D. H.; Vesselinov, V. V.

    2017-12-01

    When modeling reactive transport, reaction rates are often overestimated due to the improper assumption of perfect mixing at the support scale of the transport model. In reality, fronts tend to form between participants in thermodynamically favorable reactions, leading to segregation of reactants into islands or fingers. When such a configuration arises, reactions are limited to the interface between the reactive solutes. Closure methods for estimating control-volume-effective reaction rates in terms of quantities defined at the control volume scale do not presently exist, but their development is crucial for effective field-scale modeling. We attack this problem through a combination of analytical and numerical means. Specifically, we numerically study reactive transport through an ensemble of realizations of two-dimensional heterogeneous porous media. We then employ regression analysis to calibrate an analytically-derived relationship between reaction rate and various dimensionless quantities representing conductivity-field heterogeneity and the respective strengths of diffusion, reaction and advection.

  9. Polyimide resin composites via in situ polymerization of monomeric reactants

    Science.gov (United States)

    Cavano, P. J.

    1974-01-01

    Thermo-oxidatively stable polyimide/graphite-fiber composites were prepared using a unique in situ polymerization of monomeric reactants directly on reinforcing fibers. This was accomplished by using an aromatic diamine and two ester-acids in a methyl alcohol solvent, rather than a previously synthesized prepolymer varnish, as with other A-type polyimides. A die molding procedure was developed and a composite property characterization conducted with high modulus graphite fiber tow. Flexure, tensile, compressive, and shear tests were conducted at temperatures from 72 to 650 F on laminates before and after exposures at the given temperatures in an air environment for times up to 1000 hours. The composite material was determined to be oxidatively, thermally, and hydrolytically stable.

  10. Solid-state photoelectrochemical H2 generation with gaseous reactants

    International Nuclear Information System (INIS)

    Iwu, Kingsley O.; Galeckas, Augustinas; Kuznetsov, Andrej Yu.; Norby, Truls

    2013-01-01

    Photocurrent and H 2 production were demonstrated in an all solid-state photoelectrochemical cell employing gaseous methanol and water vapour at the photoanode. Open circuit photovoltage of around −0.4 V and short circuit photocurrent of up to 250 μA/cm 2 were obtained. At positive bias, photocurrent generation was limited by the irradiance, i.e., the amount of photogenerated charge carriers at the anode. Time constants and impedance spectra showed an electrochemical capacitance of the cell of about 15 μF/cm 2 in the dark, which increased with increasing irradiance. With only water vapour at the anode, the short circuit photocurrent was about 6% of the value with gaseous methanol and water vapour. The photoanode and electrocatalyst on carbon paper support were affixed to the proton conducting membrane using Nafion ® as adhesive, an approach that yielded photocurrents up to 15 times better than that of a cell assembled by hot-pressing, in spite of the overall cell resistance of the latter being up to five times less than that of the former. This is attributed, at least partially, to reactants being more readily available at the photoanode of the better performing cell

  11. Temperature modulation and quadrature detection for selective titration of two-state exchanging reactants.

    Science.gov (United States)

    Zrelli, K; Barilero, T; Cavatore, E; Berthoumieux, H; Le Saux, T; Croquette, V; Lemarchand, A; Gosse, C; Jullien, L

    2011-04-01

    Biological samples exhibit huge molecular diversity over large concentration ranges. Titrating a given compound in such mixtures is often difficult, and innovative strategies emphasizing selectivity are thus demanded. To overcome limitations inherent to thermodynamics, we here present a generic technique where discrimination relies on the dynamics of interaction between the target of interest and a probe introduced in excess. Considering an ensemble of two-state exchanging reactants submitted to temperature modulation, we first demonstrate that the amplitude of the out-of-phase concentration oscillations is maximum for every compound involved in a reaction whose equilibrium constant is equal to unity and whose relaxation time is equal to the inverse of the excitation angular frequency. Taking advantage of this feature, we next devise a highly specific detection protocol and validate it using a microfabricated resistive heater and an epifluorescence microscope, as well as labeled oligonucleotides to model species displaying various dynamic properties. As expected, quantification of a sought for strand is obtained even if interfering reagents are present in similar amounts. Moreover, our approach does not require any separation and is compatible with imaging. It could then benefit some of the numerous binding assays performed every day in life sciences.

  12. Pituitary adenylate cyclase 1 receptor internalization and endosomal signaling mediate the pituitary adenylate cyclase activating polypeptide-induced increase in guinea pig cardiac neuron excitability.

    Science.gov (United States)

    Merriam, Laura A; Baran, Caitlin N; Girard, Beatrice M; Hardwick, Jean C; May, Victor; Parsons, Rodney L

    2013-03-06

    After G-protein-coupled receptor activation and signaling at the plasma membrane, the receptor complex is often rapidly internalized via endocytic vesicles for trafficking into various intracellular compartments and pathways. The formation of signaling endosomes is recognized as a mechanism that produces sustained intracellular signals that may be distinct from those generated at the cell surface for cellular responses including growth, differentiation, and survival. Pituitary adenylate cyclase activating polypeptide (PACAP; Adcyap1) is a potent neurotransmitter/neurotrophic peptide and mediates its diverse cellular functions in part through internalization of its cognate G-protein-coupled PAC1 receptor (PAC1R; Adcyap1r1). In the present study, we examined whether PAC1R endocytosis participates in the regulation of neuronal excitability. Although PACAP increased excitability in 90% of guinea pig cardiac neurons, pretreatment with Pitstop 2 or dynasore to inhibit clathrin and dynamin I/II, respectively, suppressed the PACAP effect. Subsequent addition of inhibitor after the PACAP-induced increase in excitability developed gradually attenuated excitability with no changes in action potential properties. Likewise, the PACAP-induced increase in excitability was markedly decreased at ambient temperature. Receptor trafficking studies with GFP-PAC1 cell lines demonstrated the efficacy of Pitstop 2, dynasore, and low temperatures at suppressing PAC1R endocytosis. In contrast, brefeldin A pretreatments to disrupt Golgi vesicle trafficking did not blunt the PACAP effect, and PACAP/PAC1R signaling still increased neuronal cAMP production even with endocytic blockade. Our results demonstrate that PACAP/PAC1R complex endocytosis is a key step for the PACAP modulation of cardiac neuron excitability.

  13. New fundamental equations of thermodynamics for systems in chemical equilibrium at a specified partial pressure of a reactant and the standard transformed formation properties of reactants

    International Nuclear Information System (INIS)

    Alberty, R.A.; Oppenheim, I.

    1993-01-01

    When temperature, pressure, and the partial pressure of a reactant are fixed, the criterion of chemical equilibrium can be expressed in terms of the transformed Gibbs energy G' that is obtained by using a Legendre transform involving the chemical potential of the reactant that is fixed. For reactions of ideal gases, the most natural variables to use in the fundamental equation are T, P', and P B , where P' is the partial pressure of the reactants other than the one that is fixed and P B is the partial pressure of the reactant that is fixed. The fundamental equation for G' yields the expression for the transformed entropy S', and a transformed enthalpy can be defined by the additional Legendre transform H'=G'+TS'. This leads to an additional form of the fundamental equation. The calculation of transformed thermodynamic properties and equilibrium compositions is discussed for a simple system and for a general multireaction system. The change, in a reaction, of the binding of the reactant that is at a specified pressure can be calculated using one of the six Maxwell equations of the fundamental equation in G'

  14. Liquid Water Transport in the Reactant Channels of Proton Exchange Membrane Fuel Cells

    Science.gov (United States)

    Banerjee, Rupak

    Water management has been identified as a critical issue in the development of PEM fuel cells for automotive applications. Water is present inside the PEM fuel cell in three phases, i.e. liquid phase, vapor phase and mist phase. Liquid water in the reactant channels causes flooding of the cell and blocks the transport of reactants to the reaction sites at the catalyst layer. Understanding the behavior of liquid water in the reactant channels would allow us to devise improved strategies for removing liquid water from the reactant channels. In situ fuel cell tests have been performed to identify and diagnose operating conditions which result in the flooding of the fuel cell. A relationship has been identified between the liquid water present in the reactant channels and the cell performance. A novel diagnostic technique has been established which utilizes the pressure drop multiplier in the reactant channels to predict the flooding of the cell or the drying-out of the membrane. An ex-situ study has been undertaken to quantify the liquid water present in the reactant channels. A new parameter, the Area Coverage Ratio (ACR), has been defined to identify the interfacial area of the reactant channel which is blocked for reactant transport by the presence of liquid water. A parametric study has been conducted to study the effect of changing temperature and the inlet relative humidity on the ACR. The ACR decreases with increase in current density as the gas flow rates increase, removing water more efficiently. With increase in temperature, the ACR decreases rapidly, such that by 60°C, there is no significant ACR to be reported. Inlet relative humidity of the gases does change the saturation of the gases in the channel, but did not show any significant effect on the ACR. Automotive powertrains, which is the target for this work, are continuously faced with transient changes. Water management under transient operating conditions is significantly more challenging and has not

  15. Complex nonlinear behaviour of a fixed bed reactor with reactant recycle

    DEFF Research Database (Denmark)

    Recke, Bodil; Jørgensen, Sten Bay

    1999-01-01

    The fixed bed reactor with reactant recycle investigated in this paper can exhibit periodic solutions. These solutions bifurcate from the steady state in a Hopf bifurcation. The Hopf bifurcation encountered at the lowest value of the inlet concentration turns the steady state unstable and marks......,that the dynamic behaviour of a fixed bed reactor with reactant recycle is much more complex than previously reported....

  16. Cryogenic exciter

    Science.gov (United States)

    Bray, James William [Niskayuna, NY; Garces, Luis Jose [Niskayuna, NY

    2012-03-13

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

  17. Quantum-dynamical Modeling of the Rydberg to Valence Excited-State Internal Conversion in Cyclobutanone and Cyclopentanone

    Directory of Open Access Journals (Sweden)

    Møller K. B.

    2013-03-01

    Full Text Available In this paper we present 4-state, 5-dimensional Vibronic Coupling Hamiltonians for cyclobutanone and cyclopentanone. Wave packet calculations using these Hamiltonians reveal that for cyclobutanone the (n,3s to (n,π* internal conversion involves direct motion in nuclear modes coupling the two states leading to fast population transfer. For cyclopentanone, internal vibrational energy redistribution is a bottleneck for activating reactive nuclear modes leading to slower population transfer.

  18. Quantum-dynamical Modeling of the Rydberg to Valence Excited-State Internal Conversion in Cyclobutanone and Cyclopentanone

    DEFF Research Database (Denmark)

    Kuhlman, T. S.; Sauer, Stephan P. A.; Solling, T. I.

    2013-01-01

    In this paper we present 4-state, 5-dimensional Vibronic Coupling Hamiltonians for cyclobutanone and cyclopentanone. Wave packet calculations using these Hamiltonians reveal that for cyclobutanone the (n,3s) to (n,π*) internal conversion involves direct motion in nuclear modes coupling the two st...... states leading to fast population transfer. For cyclopentanone, internal vibrational energy redistribution is a bottleneck for activating reactive nuclear modes leading to slower population transfer....

  19. General theory of the multistage geminate reactions of the isolated pairs of reactants. II. Detailed balance and universal asymptotes of kinetics.

    Science.gov (United States)

    Kipriyanov, Alexey A; Doktorov, Alexander B

    2014-10-14

    The analysis of general (matrix) kinetic equations for the mean survival probabilities of any of the species in a sample (or mean concentrations) has been made for a wide class of the multistage geminate reactions of the isolated pairs. These kinetic equations (obtained in the frame of the kinetic approach based on the concept of "effective" particles in Paper I) take into account various possible elementary reactions (stages of a multistage reaction) excluding monomolecular, but including physical and chemical processes of the change in internal quantum states carried out with the isolated pairs of reactants (or isolated reactants). The general basic principles of total and detailed balance have been established. The behavior of the reacting system has been considered on macroscopic time scales, and the universal long-term kinetics has been determined.

  20. Coulomb excitation

    International Nuclear Information System (INIS)

    McGowan, F.K.; Stelson, P.H.

    1974-01-01

    The theory of Coulomb excitation and a brief review of pertinent treatments of the Coulomb excitation process that are useful for the analysis of experiments are given. Examples demonstrating the scope of nuclear structure information obtainable from gamma spectroscopy are presented. Direct Elambda excitation of 232 Th is discussed in terms of the one phonon octupole vibrational spectrum. B(MI) reduced transition probabilities resulting from Coulomb excitation of odd-A deformed nuclei with heavy ions are presented as a test of the rotational model. The use of gamma ray coincidence and particle-gamma coincidence as tools for investigating Coulomb excitation is discussed. (U.S.)

  1. The effects of combined therapy of rheumatoid arthritis on the acute phase reactants.

    Science.gov (United States)

    Rexhepi, Sylejman; Rexhepi, Mjellma; Sahatçiu-Meka, Vjollca; Pllana, Ejup; Dragusha, Gani; Gashi, Masar; Rexhepi, Blerta

    2009-01-01

    The paper presents the results of studies of acute phase reactants in the 60 treated patients with rheumatoid arthritis. Patients were divided into two groups, depending on the applied treatment: group I (n = 30) was treated with methotrexate, sulfasalazine and hydroxychloroquine, and group II (n = 30) with methotrexate. The results of our study shows that there is a statistically significant reduction in the value of acute phase reactants and clinical parameters after treatment in both investigated groups of patients, and also a significant statistical difference between the first and second group of treated patients.

  2. Teachers' Misconceptions about the Effects of Addition of More Reactants or Products on Chemical Equilibrium

    Science.gov (United States)

    Cheung, Derek; Ma, Hong-jia; Yang, Jie

    2009-01-01

    The importance of research on misconceptions about chemical equilibrium is well recognized by educators, but in the past, researchers' interest has centered on student misconceptions and has neglected teacher misconceptions. Focusing on the effects of adding more reactants or products on chemical equilibrium, this article discusses the various…

  3. Catalytic membrane in denitrification of water: a means to facilitate intraporous diffusion of reactants

    NARCIS (Netherlands)

    Ilinich, O.M.; Cuperus, F.P.; Gemert, van R.W.; Gribov, E.N.; Nosova, L.V.

    2000-01-01

    The series of mono- and bi-metallic catalysts with Pd and/or Cu supported over γ-Al 2O 3 was investigated with respect to reduction of nitrate and nitrite ions in water by hydrogen. Pronounced limitations of catalytic performance due to intraporous diffusion of the reactants were observed in the

  4. Exciter switch

    Science.gov (United States)

    Mcpeak, W. L.

    1975-01-01

    A new exciter switch assembly has been installed at the three DSN 64-m deep space stations. This assembly provides for switching Block III and Block IV exciters to either the high-power or 20-kW transmitters in either dual-carrier or single-carrier mode. In the dual-carrier mode, it provides for balancing the two drive signals from a single control panel located in the transmitter local control and remote control consoles. In addition to the improved switching capabilities, extensive monitoring of both the exciter switch assembly and Transmitter Subsystem is provided by the exciter switch monitor and display assemblies.

  5. Electromagnetic-field dependence of the internal excited state of the polaron and the qubit in quantum dot with thickness

    Science.gov (United States)

    Bai, Xu-Fang; Xin, Wei; Yin, Hong-Wu; Eerdunchaolu

    2017-06-01

    The electromagnetic-field dependence of the ground and the first excited-state (GFES) energy eigenvalues and eigenfunctions of the strong-coupling polaron in a quantum dot (QD) was studied for various QD thicknesses by using the variational method of the Pekar type (VMPT). On this basis, we construct a qubit in the quantum dot (QQD) by taking a two-level structure of the polaron as the carrier. The results of numerical calculations indicate that the oscillation period of the qubit, {itT}{in0}, increases with increasing the thickness of the quantum dot (TQD) {itL}, but decreases with increasing the cyclotron frequency of the magnetic field (CFMF) ω{in{itc}}, electric-field strength {itF}, and electron-phonon coupling strength (EPCS) α. The probability density of the qubit |Ψ({itρ}, {itz}, {itt})|{su2} presents a normal distribution of the electronic transverse coordinate ρ, significantly influenced by the TQD and effective radius of the quantum dot (ERQD) {itR}{in0}, and shows a periodic oscillation with variations in the electronic longitudinal coordinate {itz}, polar angle φ and time {itt}. The decoherence time τ and the quality factor {itQ} of the free rotation increase with increasing the CFMF ω{in{itc}}, dispersion coefficient η, and EPCS α, but decrease with increasing the electric-field strength {itF}, TQD {itL}, and ERQD {itR}{in0}. The TQD is an important parameter of the qubit. Theoretically, the target, which is to regulate the oscillation period, decoherence time and quality factor of the free rotation of the qubit, can be achieved by designing different TQDs and regulating the strength of the electromagnetic field.

  6. Contribution to the experimental study of excited levels of some light nuclei by using the method of angular correlation of internal conversion pairs and monopolar pairs; Contribution a l'etude experimentale de niveaux excites de quelques noyaux legers par la methode des Correlations angulaires des paires de conversion interne Et des paires monopolaires

    Energy Technology Data Exchange (ETDEWEB)

    Armbruster, Raymond

    1950-07-01

    In a first part, the author presents a brief theory of angular correlations of internal conversion pairs and monopolar pairs, and indicates the complete formulations which are used to compute all the angular correlations corresponding to the performed experiments. In a second part, he describes a beta spectrometer, outlines factors which govern the energy resolving power, and the peculiarity of summation of two pulses proportional to the energy of the electron and positron which build up an internal pair. In a third part, the author reports experiments of angular correlations, indicates the shapes of monopolar spectra for different angles between electron and positron emission directions, determines the multipolarity of gamma radiations from the first excited levels of {sup 13}C and {sup 12}C, and gives the angular moments, parity and isobaric spin of two excited levels of the {sup 12}C [French] Dans la premiere partie de notre travail, nous exposons une theorie sommaire des correlations angulaires des paires de conversion interne et des paires monopolaires. A la fin de cette premiere partie sont indiquees les formules completes, qui nous ont servi a calculer pratiquement toutes les correlations angulaires correspondant a nos experiences. Dans la deuxieme partie, nous decrivons un spectrometre beta a scintillation. Nous insistons surtout sur les elements qui determinent le pouvoir de resolution en energie et sur la particularite de sommation de deux impulsions proportionnelles a l'energie de l'electron et du positron formant une paire interne. Dans la troisieme partie, nous exposons nos experiences de correlations angulaires. Nous avons repris une mesure precise de la correlation angulaire des paires monopolaires provenant du niveau 6,05 Mev de l'Oxygene 16. Il nous a ete egalement possible de donner l'allure des spectres monopolaires pour differents angles formes par les directions d'emission de l'electron et du positron. Nous avons determine par la methode des

  7. On the mechanism of effective chemical reactions with turbulent mixing of reactants and finite rate of molecular reactions

    Energy Technology Data Exchange (ETDEWEB)

    Vorotilin, V. P., E-mail: VPVorotilin@yandex.ru [Russian Academy of Sciences, Institute of Applied Mechanics (Russian Federation)

    2017-01-15

    A generalization of the theory of chemical transformation processes under turbulent mixing of reactants and arbitrary values of the rate of molecular reactions is presented that was previously developed for the variant of an instantaneous reaction [13]. The use of the features of instantaneous reactions when considering the general case, namely, the introduction of the concept of effective reaction for the reactant volumes and writing a closing conservation equation for these volumes, became possible due to the partition of the whole amount of reactants into “active” and “passive” classes; the reactants of the first class are not mixed and react by the mechanism of instantaneous reactions, while the reactants of the second class approach each other only through molecular diffusion, and therefore their contribution to the reaction process can be neglected. The physical mechanism of reaction for the limit regime of an ideal mixing reactor (IMR) is revealed and described. Although formally the reaction rate in this regime depends on the concentration of passive fractions of the reactants, according to the theory presented, the true (hidden) mechanism of the reaction is associated only with the reaction of the active fractions of the reactants with vanishingly small concentration in the volume of the reactor. It is shown that the rate constant of fast chemical reactions can be evaluated when the mixing intensity of reactants is much less than that needed to reach the mixing conditions in an IMR.

  8. Low temperature synthesis of Mo2C/W2C superlattices via ultra-thin modulated reactants

    International Nuclear Information System (INIS)

    Johnson, C.D.; Johnson, D.C.

    1996-01-01

    The authors report here a synthesis method of preparing carbide superlattices using ultra-thin modulated reactants. Initial investigations into the synthesis of the binary systems, Mo 2 C and W 2 C using ultra-thin modulated reactants revealed that both can be formed at relatively low temperatures (500 and 600 C respectively). DSC and XRD data suggested a two step reaction pathway involving interdiffusion of the initial modulated reactant followed by crystallization of the final product, if the modulation length is on the order of 10 angstrom. This information was used to form Mo 2 C/W 2 C superlattices using the structure of the ultra-thin modulated reactant to control the final superlattice period. Relatively large superlattice modulations were kinetically trapped by having several repeat units of each binary within the total repeat of the initial reactant. DSC and XRD data again are consistent with a two step reaction pathway leading to the formation of carbide superlattices

  9. Acute-phase reactants in periodontal disease: current concepts and future implications.

    Science.gov (United States)

    Archana, Vilasan; Ambili, Ranjith; Nisha, Krishnavilasam Jayakumary; Seba, Abraham; Preeja, Chandran

    2015-05-01

    Periodontal disease has been linked to adverse cardiovascular events by unknown mechanisms. C-reactive protein is a systemic marker released during the acute phase of an inflammatory response and is a prognostic marker for cardiovascular disease, with elevated serum levels being reported during periodontal disease. Studies also reported elevated levels of various other acute-phase reactants in periodontal disease. It has been reported extensively in the literature that treatment of periodontal infections can significantly lower serum levels of C-reactive protein. Therefore, an understanding of the relationship between acute-phase response and the progression of periodontal disease and other systemic health complications would have a profound effect on the periodontal treatment strategies. In view of this fact, the present review highlights an overview of acute-phase reactants and their role in periodontal disease. © 2014 Wiley Publishing Asia Pty Ltd.

  10. Modeling of the reactant conversion rate in a turbulent shear flow

    Science.gov (United States)

    Frankel, S. H.; Madnia, C. K.; Givi, P.

    1992-01-01

    Results are presented of direct numerical simulations (DNS) of spatially developing shear flows under the influence of infinitely fast chemical reactions of the type A + B yields Products. The simulation results are used to construct the compositional structure of the scalar field in a statistical manner. The results of this statistical analysis indicate that the use of a Beta density for the probability density function (PDF) of an appropriate Shvab-Zeldovich mixture fraction provides a very good estimate of the limiting bounds of the reactant conversion rate within the shear layer. This provides a strong justification for the implementation of this density in practical modeling of non-homogeneous turbulent reacting flows. However, the validity of the model cannot be generalized for predictions of higher order statistical quantities. A closed form analytical expression is presented for predicting the maximum rate of reactant conversion in non-homogeneous reacting turbulence.

  11. Voiced Excitations

    National Research Council Canada - National Science Library

    Holzricher, John

    2004-01-01

    To more easily obtain a voiced excitation function for speech characterization, measurements of skin motion, tracheal tube, and vocal fold, motions were made and compared to EM sensor-glottal derived...

  12. Exciting Pools

    Science.gov (United States)

    Wright, Bradford L.

    1975-01-01

    Advocates the creation of swimming pool oscillations as part of a general investigation of mechanical oscillations. Presents the equations, procedure for deriving the slosh modes, and methods of period estimation for exciting swimming pool oscillations. (GS)

  13. Experimental investigation of laminar LPG-H{sub 2} jet diffusion flame with preheated reactants

    Energy Technology Data Exchange (ETDEWEB)

    D.P. Mishra; P. Kumar [Indian Institute of Technology, Kanpur (India). Combustion Laboratory, Department of Aerospace Engineering

    2008-10-15

    This paper presents an experimental investigation of the effect of H{sub 2} addition on flame length, soot free length fraction (SFLF), flame radiant fraction, gas temperature and emission level in LPG-H{sub 2} composite fuel jet diffusion flame for two preheated cases namely, (i) preheated air and (ii) preheated air and fuel. Results show that the H{sub 2} addition leads to a reduction in flame length which may be caused due to an increased gas temperature. Besides this, the flame length is also observed to be reduced with increasing reactants temperature. The soot free length fraction (SFLF) increases as H{sub 2} is added to fuel stream. This might have been caused by decrease in the C/H ratio in the flame and is favorable to attenuate PAH formation rate. Interestingly, the SFLF is observed to be reduced with increasing reactants temperature that may be due to reduction in induction period of soot formation caused by enhanced flame temperature. Moreover, the decreased radiant heat fraction with hydrogen addition is pertinent with the reduction in soot concentration level. The reduction in NOx emission level with H{sub 2} addition to the fuel stream is also observed. On the contrary, NOx emission level is found to be enhanced significantly with reactant temperature that can be attributed to the increase in thermal NOx through Zeldovich mechanism. 31 refs., 4 figs., 2 tabs.

  14. Design, fabrication and performance of a mixed-reactant membraneless micro direct methanol fuel cell stack

    Science.gov (United States)

    Abrego-Martínez, J. C.; Moreno-Zuria, A.; Cuevas-Muñiz, F. M.; Arriaga, L. G.; Sun, Shuhui; Mohamedi, Mohamed

    2017-12-01

    In the present work, we report the design, fabrication and evaluation of a membraneless mixed-reactant and air-breathing microfluidic direct methanol fuel cell (ML-μDMFC) stack operated in passive mode. The operation under mixed-reactant conditions was achieved by using a highly methanol-tolerant Ag/Pt/CP cathode with ultra-low Pt loading in alkaline medium. Prior to the fabrication of the stack, a flow simulation was made in order to study the behavior of the reactants stream in the microchannel through the 2 cells. Subsequently, the device was tested in passive mode using a mixture of 5 M MeOH +0.5 M KOH. The results showed that by connecting the 2 cells in series, it is possible to effectively double the voltage of a single ML-μDMFC, as well as increasing the absolute power by 75% with practically no cost increase. The stack was capable of operate continuously for more than 2 h with a single charge of 40 μL, producing an OCV of 0.89 V and a maximum power density of 3.33 mW mgPt-1. Additionally, the device exhibited good stability throughout a 10 h test.

  15. Excited states

    CERN Document Server

    Lim, Edward C

    1974-01-01

    Excited States, Volume I reviews radiationless transitions, phosphorescence microwave double resonance through optical spectra in molecular solids, dipole moments in excited states, luminescence of polar molecules, and the problem of interstate interaction in aromatic carbonyl compounds. The book discusses the molecular electronic radiationless transitions; the double resonance techniques and the relaxation mechanisms involving the lowest triplet state of aromatic compounds; as well as the optical spectra and relaxation in molecular solids. The text also describes dipole moments and polarizab

  16. Excited fermions

    International Nuclear Information System (INIS)

    Boudjema, F.; Djouadi, A.; Kneur, J.L.

    1992-01-01

    The production of excited fermions with mass above 100 GeV is considered. f→Vf (1) decay widths are calculated where V=γ, Z or W. Excited fermion pair production in e + e - annihilation and in γγ collisions, and single production in e + e - annihilation, eγ and γγ collisions is also discussed. Cross sections are calculated for all these cases. The discovery potential of the NLC at 500 GeV is compared with that of other colliders. (K.A.) 15 refs., 5 figs., 2 tabs

  17. Non-typical fluorescence studies of excited and ground state proton and hydrogen transfer

    KAUST Repository

    Gil, Michał; Kijak, Michał; Piwonski, Hubert Marek; Herbich, Jerzy; Waluk, Jacek

    2017-01-01

    Fluorescence studies of tautomerization have been carried out for various systems that exhibit single and double proton or hydrogen translocation in various environments, such as liquid and solid condensed phases, ultracold supersonic jets, and finally, polymer matrices with single emitters.We focus on less explored areas of application of fluorescence for tautomerization studies, using porphycene, a porphyrin isomer, as an example. Fluorescence anisotropy techniques allow investigations of self-exchange reactions, where the reactant and product are formally identical. Excitation with polarized light makes it possible to monitor tautomerization in single molecules and to detect their three-dimensional orientation. Analysis of fluorescence from single vibronic levels of jet-isolated porphycene not only demonstrates coherent tunneling of two internal protons, but also indicates that the process is vibrational mode-specific. Next, we present bifunctional proton donoracceptor systems, molecules that are able, depending on the environment, to undergo excited state single intramolecular or double intermolecular proton transfer. For molecules that have donor and acceptor groups located in separate moieties linked by a single bond, excited state tautomerization can be coupled to mutual twisting of the two subunits.

  18. Non-typical fluorescence studies of excited and ground state proton and hydrogen transfer

    KAUST Repository

    Gil, Michał

    2017-02-03

    Fluorescence studies of tautomerization have been carried out for various systems that exhibit single and double proton or hydrogen translocation in various environments, such as liquid and solid condensed phases, ultracold supersonic jets, and finally, polymer matrices with single emitters.We focus on less explored areas of application of fluorescence for tautomerization studies, using porphycene, a porphyrin isomer, as an example. Fluorescence anisotropy techniques allow investigations of self-exchange reactions, where the reactant and product are formally identical. Excitation with polarized light makes it possible to monitor tautomerization in single molecules and to detect their three-dimensional orientation. Analysis of fluorescence from single vibronic levels of jet-isolated porphycene not only demonstrates coherent tunneling of two internal protons, but also indicates that the process is vibrational mode-specific. Next, we present bifunctional proton donoracceptor systems, molecules that are able, depending on the environment, to undergo excited state single intramolecular or double intermolecular proton transfer. For molecules that have donor and acceptor groups located in separate moieties linked by a single bond, excited state tautomerization can be coupled to mutual twisting of the two subunits.

  19. Subsurface excitations in a metal

    DEFF Research Database (Denmark)

    Ray, M. P.; Lake, R. E.; Sosolik, C. E.

    2009-01-01

    We investigate internal hot carrier excitations in a Au thin film bombarded by hyperthermal and low energy alkali and noble gas ions. Excitations within the thin film of a metal-oxide-semiconductor device are measured revealing that ions whose velocities fall below the classical threshold given...... by the free-electron model of a metal still excite hot carriers. Excellent agreement between these results and a nonadiabatic model that accounts for the time-varying ion-surface interaction indicates that the measured excitations are due to semilocalized electrons near the metal surface....

  20. Entropy and chemical change. 1: Characterization of product (and reactant) energy distributions in reactive molecular collisions: Information and enthropy deficiency

    Science.gov (United States)

    Bernstein, R. B.; Levine, R. D.

    1972-01-01

    Optimal means of characterizing the distribution of product energy states resulting from reactive collisions of molecules with restricted distributions of initial states are considered, along with those for characterizing the particular reactant state distribution which yields a given set of product states at a specified total energy. It is suggested to represent the energy-dependence of global-type results in the form of square-faced bar plots, and of data for specific-type experiments as triangular-faced prismatic plots. The essential parameters defining the internal state distribution are isolated, and the information content of such a distribution is put on a quantitative basis. The relationship between the information content, the surprisal, and the entropy of the continuous distribution is established. The concept of an entropy deficiency, which characterizes the specificity of product state formation, is suggested as a useful measure of the deviance from statistical behavior. The degradation of information by experimental averaging is considered, leading to bounds on the entropy deficiency.

  1. Platinum- and membrane-free swiss-roll mixed-reactant alkaline fuel cell.

    Science.gov (United States)

    Aziznia, Amin; Oloman, Colin W; Gyenge, Előd L

    2013-05-01

    Eliminating the expensive and failure-prone proton exchange membrane (PEM) together with the platinum-based anode and cathode catalysts would significantly reduce the high capital and operating costs of low-temperature (<373 K) fuel cells. We recently introduced the Swiss-roll mixed-reactant fuel cell (SR-MRFC) concept for borohydride-oxygen alkaline fuel cells. We now present advances in anode electrocatalysis for borohydride electrooxidation through the development of osmium nanoparticulate catalysts supported on porous monolithic carbon fiber materials (referred to as an osmium 3D anode). The borohydride-oxygen SR-MRFC operates at 323 K and near atmospheric pressure, generating a peak power density of 1880 W m(-2) in a single-cell configuration by using an osmium-based anode (with an osmium loading of 0.32 mg cm(-2)) and a manganese dioxide gas-diffusion cathode. To the best of our knowledge, 1880 W m(-2) is the highest power density ever reported for a mixed-reactant fuel cell operating under similar conditions. Furthermore, the performance matches the highest reported power densities for conventional dual chamber PEM direct borohydride fuel cells. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Time resolved FTIR study of the catalytic CO oxidation under periodic variation of the reactant concentration

    Energy Technology Data Exchange (ETDEWEB)

    Kritzenberger, J; Wokaun, A [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1997-06-01

    Oxidation of CO over palladium/zirconia catalyst obtained from an amorphous Pd{sub 25}Zr{sub 75} precursor was investigated by time resolved FTIR spectroscopy. Sine wave shaped modulation of the reactant concentration, i.e. variation of CO or O{sub 2} partial pressure, was used to induce variations of the IR signals of product (CO{sub 2}) and unconverted reactant (CO), which were detected in a multi-pass absorption cell. The phase shift {phi} between external perturbation and variation of the CO{sub 2} signal was examined in dependence on temperature (100{sup o}C{<=}T{<=}350{sup o}C) and modulation frequency (1.39x10{sup -4}Hz{<=}{omega}{<=}6.67x10{sup -2}Hz). From the phase shift values, a simple Eley-Rideal mechanism is excluded, and the rate limiting step of the Langmuir-Hinshelwood mechanism for the CO oxidation may be identified. Adsorption and possible surface movement of CO to the actual reaction site determine the rate of the CO oxidation on the palladium/zirconia catalyst used in our study. The introduction of an external perturbation is a first step towards the application of two-dimensional infrared spectroscopy to heterogeneous catalyzed reactions. (author) 3 figs., 4 refs.

  3. International Observe the Moon Night - An Opportunity to Participate in the Year of the Solar System While Sharing the Excitement of Lunar Science and Exploration with the Public

    Science.gov (United States)

    Bleacher, L.; Daou, D.; Day, B. H.; Hsu, B. C.; Jones, A. P.; Mitchell, B.; Shaner, A. J.; Shipp, S. S.

    2010-12-01

    International Observe the Moon Night (InOMN) is a multi-nation effort to share the excitement of recent lunar missions and new science results with education communities, amateur astronomers, space enthusiasts, and the general public. It is also intended to encourage the world to experience the thrill of observing Earth’s closest neighbor. The inaugural InOMN took place on September 18, 2010. People in over 26 countries gathered together in groups big and small to learn about the Moon through presentations by scientists, astronomers, and engineers; participate in hands-on activities; and observe the Moon through telescopes, binoculars, and the naked eye. Next year’s InOMN will take place on October 8, 2011 during the Year of the Solar System (YSS). The October 2011 YSS theme will be “Moons/Rings Across the Solar System.” InOMN is perfectly suited as an event that any museum, science center, planetarium, university, school, or other group can implement to celebrate YSS. The InOMN Coordinating Committee has developed a variety of resources and materials to make it easy to host an InOMN event of any size. Interested groups are encouraged to utilize the InOMN website (observethemoonnight.org) in planning their InOMN event for 2011/YSS. The website contains links to Moon resources, educational activities, suggestions for hosting an event, free downloads of logos and flyers for advertising an event, and contests. New for 2011 will be a discussion forum for event hosts to share their plans, tips, and experiences. Together, YSS and InOMN will enable the public to maintain its curiosity about the Moon and to gain a better understanding of the Moon’s formation, evolution, and place in the night sky.

  4. "Inverted" Solvent Effect on Charge Transfer in the Excited State.

    Science.gov (United States)

    Nau; Pischel

    1999-10-04

    Faster in cyclohexane than in acetonitrile is the fluorescence quenching of the azoalkane 2,3-diazabicyclo[2.2.2]oct-2-ene (DBO) by amines and sulfides. Although this photoreaction is induced by charge transfer (CT; see picture) and exciplexes are formed, the increase in the dipole moment of the exciplex is not large enough to offset the solvent stabilization of the excited reactants, and an "inverted" solvent effect results.

  5. Excited baryons

    International Nuclear Information System (INIS)

    Mukhopadhyay, N.C.

    1986-01-01

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

  6. Excited baryons

    Energy Technology Data Exchange (ETDEWEB)

    Mukhopadhyay, N.C.

    1986-01-01

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

  7. Effects of ligand substitution on the excited state dynamics of the Ru(dcbpy)(CO) 2I 2 complex

    Science.gov (United States)

    Lehtovuori, Viivi; Kallioinen, Jani; Myllyperkiö, Pasi; Haukka, Matti; Korppi-Tommola, Jouko

    2003-11-01

    Spectroscopic evidence suggest [PCCP 3 (2001) 1992] that illumination with visible light of the [ trans-I-Ru(dcbpy)(CO) 2I 2] (dcbpy= 4,4 '-dicarboxy-2,2 '-bipyridine) complex in solution induces dissociation of a CO group followed by reorganization of the ligands and attachment of a solvent molecule. In the present study, we report results on excited state dynamics of this ruthenium complex and its photoproduct. Femtosecond transient absorption measurements reveal dominance of excited state absorption of the reactant and the photoproduct [ cis-I-Ru(dcbpy)(CO)(Sol)I 2] (Sol=ethanol or acetonitrile) in the visible spectral region. The time-resolved measurements for the reactant at 77 K indicate interligand charge transfer from mixed Ru-I states to empty dcbpy orbitals. For the photoproduct, no such transfer was observed. In both complexes recovery from the lowest energy excited triplet state to the ground state occurs via two channels: radiative relaxation and a parallel barrier controlled non-radiative relaxation. The barrier is much higher in the reactant (about 850 cm -1) than in the product. A combination of DFT and ZINDO/CI calculations was used to estimate excited singlet and triplet spectra of the reactant and the product molecules. Calculated singlet-triplet difference spectra qualitatively match the observed transient spectra 500 fs after excitation supporting the idea that observed excited state relaxation occurs from the triplet states in both complexes.

  8. Effects of ligand substitution on the excited state dynamics of the Ru(dcbpy)(CO)2I2 complex

    International Nuclear Information System (INIS)

    Lehtovuori, Viivi; Kallioinen, Jani; Myllyperkioe, Pasi; Haukka, Matti; Korppi-Tommola, Jouko

    2003-01-01

    Spectroscopic evidence suggest [PCCP 3 (2001) 1992] that illumination with visible light of the [trans-I-Ru(dcbpy)(CO) 2 I 2 ] (dcbpy4,4 ' -dicarboxy-2,2 ' -bipyridine) complex in solution induces dissociation of a CO group followed by reorganization of the ligands and attachment of a solvent molecule. In the present study, we report results on excited state dynamics of this ruthenium complex and its photoproduct. Femtosecond transient absorption measurements reveal dominance of excited state absorption of the reactant and the photoproduct [cis-I-Ru(dcbpy)(CO)(Sol)I 2 ] (Sol=ethanol or acetonitrile) in the visible spectral region. The time-resolved measurements for the reactant at 77 K indicate interligand charge transfer from mixed Ru-I states to empty dcbpy orbitals. For the photoproduct, no such transfer was observed. In both complexes recovery from the lowest energy excited triplet state to the ground state occurs via two channels: radiative relaxation and a parallel barrier controlled non-radiative relaxation. The barrier is much higher in the reactant (about 850 cm -1 ) than in the product. A combination of DFT and ZINDO/CI calculations was used to estimate excited singlet and triplet spectra of the reactant and the product molecules. Calculated singlet-triplet difference spectra qualitatively match the observed transient spectra 500 fs after excitation supporting the idea that observed excited state relaxation occurs from the triplet states in both complexes

  9. A Regime Diagram for Autoignition of Homogeneous Reactant Mixtures with Turbulent Velocity and Temperature Fluctuations

    KAUST Repository

    Im, Hong G.; Pal, Pinaki; Wooldridge, Margaret S.; Mansfield, Andrew B.

    2015-01-01

    A theoretical scaling analysis is conducted to propose a diagram to predict weak and strong ignition regimes for a compositionally homogeneous reactant mixture with turbulent velocity and temperature fluctuations. The diagram provides guidance on expected ignition behavior based on the thermo-chemical properties of the mixture and the flow/scalar field conditions. The analysis is an extension of the original Zeldovich’s analysis by combining the turbulent flow and scalar characteristics in terms of the characteristic Damköhler and Reynolds numbers of the system, thereby providing unified and comprehensive understanding of the physical and chemical mechanisms controlling ignition characteristics. Estimated parameters for existing experimental measurements in a rapid compression facility show that the regime diagram predicts the observed ignition characteristics with good fidelity.

  10. A Regime Diagram for Autoignition of Homogeneous Reactant Mixtures with Turbulent Velocity and Temperature Fluctuations

    KAUST Repository

    Im, Hong G.

    2015-04-02

    A theoretical scaling analysis is conducted to propose a diagram to predict weak and strong ignition regimes for a compositionally homogeneous reactant mixture with turbulent velocity and temperature fluctuations. The diagram provides guidance on expected ignition behavior based on the thermo-chemical properties of the mixture and the flow/scalar field conditions. The analysis is an extension of the original Zeldovich’s analysis by combining the turbulent flow and scalar characteristics in terms of the characteristic Damköhler and Reynolds numbers of the system, thereby providing unified and comprehensive understanding of the physical and chemical mechanisms controlling ignition characteristics. Estimated parameters for existing experimental measurements in a rapid compression facility show that the regime diagram predicts the observed ignition characteristics with good fidelity.

  11. Computational Modelling of Thermal Stability in a Reactive Slab with Reactant Consumption

    Directory of Open Access Journals (Sweden)

    O. D. Makinde

    2012-01-01

    Full Text Available This paper investigates both the transient and the steady state of a one-step nth-order oxidation exothermic reaction in a slab of combustible material with an insulated lower surface and an isothermal upper surface, taking into consideration reactant consumption. The nonlinear partial differential equation governing the transient reaction-diffusion problem is solved numerically using a semidiscretization finite difference technique. The steady-state problem is solved using a perturbation technique together with a special type of the Hermite-Padé approximants. Graphical results are presented and discussed quantitatively with respect to various embedded parameters controlling the systems. The crucial roles played by the boundary conditions in determining the thermal ignition criticality are demonstrated.

  12. SHS synthesis of Si-SiC composite powders using Mg and reactants from industrial waste

    Science.gov (United States)

    Chanadee, Tawat

    2017-11-01

    Si-SiC composite powders were synthesized by self-propagating high-temperature synthesis (SHS) using reactants of fly ash-based silica, sawdust-based activated carbon, and magnesium. Fly ash-based silica and sawdust-based activated carbon were prepared from coal mining fly ash and Para rubber-wood sawdust, respectively. The work investigated the effects of the synthesis atmosphere (air and Ar) on the phase and morphology of the SHS products. The SHS product was leached by a two-step acid leaching processes, to obtain the Si-SiC composite powder. The SHS product and SHS product after leaching were characterized by X-ray diffractometry, scanning electron microscopy and energy dispersive X-ray spectrometry. The results indicated that the SHS product synthesized in air consisted of Si, SiC, MgO, and intermediate phases (SiO2, Mg, Mg2SiO4, Mg2Si), whereas the SHS product synthesized in Ar consisted of Si, SiC, MgO and a little Mg2SiO4. The SiC content in the leached-SHS product was higher when Ar was used as the synthesis atmosphere. As well as affecting the purity, the synthesis atmospheres also affected the average crystalline sizes of the products. The crystalline size of the product synthesized in Ar was smaller than that of the product synthesized in air. All of the results showed that fly ash and sawdust could be effective waste-material reactants for the synthesis of Si-SiC composite powders.

  13. K{sub 2}MnF{sub 5}·H{sub 2}O as reactant for synthesizing highly efficient red emitting K{sub 2}TiF{sub 6}:Mn{sup 4+} phosphors by a modified cation exchange approach

    Energy Technology Data Exchange (ETDEWEB)

    Han, Tao, E-mail: danbaiht@126.com; Wang, Jun; Lang, Tianchun; Tu, Mingjing; Peng, Lingling

    2016-11-01

    As reactant for synthesizing K{sub 2}TiF{sub 6}:Mn{sup 4+} phosphors, the cross-shaped and cuboid-shaped K{sub 2}MnF{sub 5}·H{sub 2}O powders were prepared by the simple chemical method. Based on the reaction mechanism, oxidizing K{sub 2}MnF{sub 5}·H{sub 2}O (Mn{sup 3+}) to Mn{sup 4+} by KMnO{sub 4} (Mn{sup 7+}), a modified cation exchange approach for synthesizing highly efficient red emitting K{sub 2}TiF{sub 6}:Mn{sup 4+} phosphor was proposed. The obtained K{sub 2}TiF{sub 6}:Mn{sup 4+} (2.7–5.3 at.%) phosphors have the size of 30–80 μm with a rough surface, their emission spectra consist of five narrow bands extending from 580 to 660 nm with the strongest peak at 634.8 nm, whose relative emitting intensity depends on the molar ratio of KMnO{sub 4} to K{sub 2}MnF{sub 5}·H{sub 2}O (the platform value = 3.2), and two broad excitation bands are peaking at ∼365 nm and ∼460 nm. The internal quantum yield of our synthesized K{sub 2}TiF{sub 6}:Mn{sup 4+} phosphors is up to 82.5%, which is higher than the commercial CaAlSiN{sub 3}:Eu{sup 2+} value, their excitation bands peak at ∼460 and ∼365 nm are consistent with those of Y{sub 3}A{sub 5}O{sub 12}:Ce{sup 3+} phosphors and their emission bands are more suitable for the sensitivity curve of photopic human vision. In addition, our synthesized phosphors show better thermal quenching properties. These findings show a large potential of the synthesized K{sub 2}TiF{sub 6}:Mn{sup 4+} phosphors for commercialization. - Highlights: • We synthesize the cross-shaped and cuboid-shaped K{sub 2}MnF{sub 5}·H{sub 2}O. • K{sub 2}MnF{sub 5}·H{sub 2}O is as a reactant for synthesizing K{sub 2}TiF{sub 6}:Mn{sup 4+} phosphors. • K{sub 2}TiF{sub 6}:Mn{sup 4+} will improve the current white LED with high CRI for indoor lighting.

  14. Study of the ionization of alkane-electron scavenger reactant mixtures irradiated by 60Co gamma rays

    International Nuclear Information System (INIS)

    Bonnet, Jacques.

    1977-01-01

    This study deals with ionization of alkane-electron scavenger reactant mixtures, irradiated by 60 Co γ-rays. It is shown that the extrapolated free-ion yields (extrapolated yield method) decrease with the reactant concentration. On the basis of ONSAGER model and theoretical treatment of MOZUMDER, the cross sections of epithermal electron attachment in hexane, cyclohexane, 2,2-dimethylbutane, cyclopentane, 2,2,4-trimethylpentane for CCl 4 , C 7 F 14 , C 6 H 5 Br, C 6 H 5 Cl, C 6 F 14 , (C 6 H 5 ) 2 are determined. A comparison between gas-phase and liquid-phase cross sections is established [fr

  15. Transesterification of castor oil usingMgO/SiO2 catalyst and coconutoilas co-reactant

    OpenAIRE

    Kamisah D. Pandiangan; Novesar Jamarun; Syukri Arief; Wasinton Simanjuntak

    2016-01-01

    This paper describes the transesterification of castor oil with the use of coconut oil as co-reactant and MgO/SiO2as heterogeneous base catalyst. The catalyst was preparedfrom rice husk silica and magnesium nitrate by sol-gel method, with MgO load of 20% relative to silica, and then subjected to sintering treatment at 600 oC for 6 hours. A series of experiments was carried out, indicating that the use of coconut oil as co-reactant significantly promoted the conversion of castor oil into b...

  16. International conference: Features of nuclear excitation states and mechanisms of nuclear reactions. 51. Meeting on nuclear spectroscopy and nuclear structure. The book of abstracts

    International Nuclear Information System (INIS)

    2001-01-01

    Results of the LI Meeting on Nuclear Spectroscopy and Nuclear Structure are presented. Properties of excited states of atomic nuclei and mechanisms of nuclear reactions are considered. Studies on the theory of nucleus and fundamental interactions pertinent to experimental study of nuclei properties and mechanisms of nuclear reactions, technique and methods of experiment, application of nuclear-physical method, are provided [ru

  17. Exotic nuclear excitations

    CERN Document Server

    Pancholi, S C

    2011-01-01

    By providing the reader with a foundational background in high spin nuclear structure physics and exploring exciting current discoveries in the field, this book presents new phenomena in a clear and compelling way. The quest for achieving the highest spin states has resulted in some remarkable successes which this monograph will address in comprehensive detail. The text covers an array of pertinent subject matter, including the rotational alignment and bandcrossings, magnetic rotation, triaxial strong deformation and wobbling motion and chirality in nuclei. Dr. Pancholi offers his readers a clearly-written and up-to-date treatment of the topics covered. The prerequisites for a proper appreciation are courses in nuclear physics and nuclear models and measurement techniques of observables like gamma-ray energies, intensities, multi-fold coincidences, angular correlations or distributions, linear polarization, internal conversion coefficients, short lifetime (pico-second range) of excited states etc. and instrum...

  18. A continuous flow microfluidic calorimeter: 3-D numerical modeling with aqueous reactants

    Energy Technology Data Exchange (ETDEWEB)

    Sen, Mehmet A., E-mail: mehmet.sen@mathworks.com [Northeastern University, Department of Mechanical and Industrial Engineering, 360 Hungtington Avenue, 334 Snell Engineering Center, Boston, MA 02115 (United States); Kowalski, Gregory J., E-mail: gkowal@coe.neu.edu [Northeastern University, Department of Mechanical and Industrial Engineering, 360 Hungtington Avenue, 334 Snell Engineering Center, Boston, MA 02115 (United States); Fiering, Jason, E-mail: jfiering@draper.com [Charles Stark Draper Laboratory, 555 Technology Square, Cambridge, MA 02139 (United States); Larson, Dale, E-mail: dlarson@draper.com [Charles Stark Draper Laboratory, 555 Technology Square, Cambridge, MA 02139 (United States)

    2015-03-10

    Highlights: • A co-flow microreactor is modeled in flow, reaction/diffusion, and thermal domains. • Analysis shows how arrayed temperature sensors can provide enthalpy of reaction. • Optical plasmonic temperature sensors could be arrayed suitably for calorimetry. • The reactor studied has a volume of 25 nL. - Abstract: A computational analysis of the reacting flow field, species diffusion and heat transfer processes with thermal boundary layer effects in a microchannel reactor with a coflow configuration was performed. Two parallel adjacent streams of aqueous reactants flow along a wide, shallow, enclosed channel in contact with a substrate, which is affixed to a temperature controlled plate. The Fluent computational fluid dynamics package solved the Navier–Stokes, mass transport and energy equations. The energy model, including the enthalpy of reaction as a nonuniform heat source, was validated by calculating the energy balance at several control volumes in the microchannel. Analysis reveals that the temperature is nearly uniform across the channel thickness, in the direction normal to the substrate surface; hence, measurements made by sensors at or near the surface are representative of the average temperature. Additionally, modeling the channel with a glass substrate and a silicone cover shows that heat transfer is predominantly due to the glass substrate. Finally, using the numerical results, we suggest that a microcalorimeter could be based on this configuration, and that temperature sensors such as optical nanohole array sensors could have sufficient spatial resolution to determine enthalpy of reaction.

  19. Switching from Reactant to Substrate Engineering in the Selective Synthesis of Graphene Nanoribbons.

    Science.gov (United States)

    Merino-Díez, Néstor; Lobo-Checa, Jorge; Nita, Pawel; Garcia-Lekue, Aran; Basagni, Andrea; Vasseur, Guillaume; Tiso, Federica; Sedona, Francesco; Das, Pranab K; Fujii, Jun; Vobornik, Ivana; Sambi, Mauro; Pascual, José Ignacio; Ortega, J Enrique; de Oteyza, Dimas G

    2018-04-27

    The challenge of synthesizing graphene nanoribbons (GNRs) with atomic precision is currently being pursued along a one-way road, based on the synthesis of adequate molecular precursors that react in predefined ways through self-assembly processes. The synthetic options for GNR generation would multiply by adding a new direction to this readily successful approach, especially if both of them can be combined. We show here how GNR synthesis can be guided by an adequately nanotemplated substrate instead of by the traditionally designed reactants. The structural atomic precision, unachievable to date through top-down methods, is preserved by the self-assembly process. This new strategy's proof-of-concept compares experiments using 4,4''-dibromo-para-terphenyl as a molecular precursor on flat Au(111) and stepped Au(322) substrates. As opposed to the former, the periodic steps of the latter drive the selective synthesis of 6 atom-wide armchair GNRs, whose electronic properties have been further characterized in detail by scanning tunneling spectroscopy, angle resolved photoemission, and density functional theory calculations.

  20. THE INFLUENCE OF BENZENE AS A TRACE REACTANT IN TITAN AEROSOL ANALOGS

    Energy Technology Data Exchange (ETDEWEB)

    Trainer, Melissa G. [Planetary Environments Laboratory, Code 699, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Sebree, Joshua A. [NASA Postdoctoral Program Fellow, Code 699, Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Heidi Yoon, Y.; Tolbert, Margaret A., E-mail: melissa.trainer@nasa.gov [Cooperative Institute for Research in Environmental Sciences, University of Colorado at Boulder, Box 216 UCB, Boulder, CO 80309 (United States)

    2013-03-20

    Benzene has been detected in Titan's atmosphere by Cassini instruments, with concentrations ranging from sub-ppb in the stratosphere to ppm in the ionosphere. Sustained levels of benzene in the haze formation region could signify that it is an important reactant in the formation of Titan's organic aerosol. To date, there have not been laboratory investigations to assess the influence of benzene on aerosol properties. We report a laboratory study on the chemical composition of organic aerosol formed from C{sub 6}H{sub 6}/CH{sub 4}/N{sub 2} via far ultraviolet irradiation (120-200 nm). The compositional results are compared to those from aerosol generated by a more ''traditional Titan'' mixture of CH{sub 4}/N{sub 2}. Our results show that even a trace amount of C{sub 6}H{sub 6} (10 ppm) has significant impact on the chemical composition and production rates of organic aerosol. There are several pathways by which photolyzed benzene may react to form larger molecules, both with and without the presence of CH{sub 4}, but many of these reaction mechanisms are only beginning to be explored for the conditions at Titan. Continued work investigating the influence of benzene in aerosol growth will advance understanding of this previously unstudied reaction system.

  1. Modification of the liquid cooling channel of PEMFCs for their operation with dry reactant gases

    International Nuclear Information System (INIS)

    Shyu, Jin-Cherng; Hsueh, Kan-Lin; Tsau, Fanghei; Chen, Fa-Lin

    2011-01-01

    In order to tackle both water and thermal problems, a modified PEMFC is proposed in the present study for its operation with dry reactant gases via the modification of liquid cooling channel with circulating liquid electrolyte. Fuel cell with both circulating liquid electrolyte and solid polymer membrane operated with either dry or humidified H 2 /O 2 is compared in the present study at temperatures of 40, 50, 65, and 80 o C, respectively. The measured E-I data show that such single cell can be operated at 80 o C without humidification. Besides, a semi-empirical equation to predict the current/voltage relationship, and the electrochemical impedance method are also employed in the present study for cell resistance analysis. The analysis results show that the high interfacial resistance should be one of the major reasons for the inferior performance of the present cell. Based on the discovery, an improvement of the present fuel cell is further proposed by Nafion ionomer spreading on the electrode before the assembly of membrane and electrode. The maximum power density of the cell after electrode treatment reaches 75 mW/cm 2 for dry H 2 /O 2 operation at 0.4 V, which is almost threefold improvement compared with that without electrode treatment.

  2. A continuous flow microfluidic calorimeter: 3-D numerical modeling with aqueous reactants

    International Nuclear Information System (INIS)

    Sen, Mehmet A.; Kowalski, Gregory J.; Fiering, Jason; Larson, Dale

    2015-01-01

    Highlights: • A co-flow microreactor is modeled in flow, reaction/diffusion, and thermal domains. • Analysis shows how arrayed temperature sensors can provide enthalpy of reaction. • Optical plasmonic temperature sensors could be arrayed suitably for calorimetry. • The reactor studied has a volume of 25 nL. - Abstract: A computational analysis of the reacting flow field, species diffusion and heat transfer processes with thermal boundary layer effects in a microchannel reactor with a coflow configuration was performed. Two parallel adjacent streams of aqueous reactants flow along a wide, shallow, enclosed channel in contact with a substrate, which is affixed to a temperature controlled plate. The Fluent computational fluid dynamics package solved the Navier–Stokes, mass transport and energy equations. The energy model, including the enthalpy of reaction as a nonuniform heat source, was validated by calculating the energy balance at several control volumes in the microchannel. Analysis reveals that the temperature is nearly uniform across the channel thickness, in the direction normal to the substrate surface; hence, measurements made by sensors at or near the surface are representative of the average temperature. Additionally, modeling the channel with a glass substrate and a silicone cover shows that heat transfer is predominantly due to the glass substrate. Finally, using the numerical results, we suggest that a microcalorimeter could be based on this configuration, and that temperature sensors such as optical nanohole array sensors could have sufficient spatial resolution to determine enthalpy of reaction

  3. Glycerol transesterification with ethyl acetate to synthesize acetins using ethyl acetate as reactant and entrainer

    Directory of Open Access Journals (Sweden)

    Amin Shafiei

    2017-03-01

    Full Text Available Transesterification of glycerol with ethyl acetate was performed over acidic catalysts in the batch and semi-batch systems. Ethyl acetate was used as reactant and entrainer to remove the produced ethanol during the reaction, through azeotrope formation. Since the azeotrope of ethyl acetate and ethanol forms at 70 oC, all the experiments were performed at this temperature. Para-toluene sulfonic acid, sulfuric acid, and Amberlyst 36 were used as catalyst. The effect of process parameters including ethyl acetate to glycerol molar ratio (6-12, reaction time (3-9 h, and the catalyst to glycerol weight (2.5-9.0%, on the conversion and products selectivities were investigated. Under reflux conditions, 100% glycerol conversion was obtained with 45%, 44%, and 11% selectivity to monoacetin, diacetin, and triacetin, respectively. Azeotropic reactive distillation led to 100% conversion of glycerol with selectivities of 3%, 48% and 49% for monoacetin, diacetin, and triacetin. During the azeotropic reactive distillation, it was possible to remove ethanol to shift the equilibrium towards diacetin and triacetin. Therefore, the total selectivity to diacetin and triacetin was increased from 55% to 97% through azeotropic distillation.

  4. Use of Gas Transported Reactants for Uranium Remediation in Vadose Zone Sediments

    International Nuclear Information System (INIS)

    Szecsody, James E.; Zhong, Lirong; Truex, Michael J.; Resch, Charles T.; Williams, Mark D.

    2010-01-01

    This laboratory-scale investigation is focused on decreasing mobility of uranium in subsurface contaminated sediments in the vadose zone by in situ geochemical manipulation at low water content. This geochemical manipulation of the sediment surface phases included reduction, pH change (acidic and alkaline), and additions of chemicals (phosphate, ferric iron) to form specific precipitates. Reactants were advected into 1-D columns packed with Hanford 200 area U-contaminated sediment as a reactive gas (for CO2, NH3, H2S, SO2), with a 0.1% water content mist (for NaOH, Fe(III), HCl, PO4) and with a 1% water content foam (for PO4). Because uranium is present in the sediment in multiple phases, changes in U surface phases were evaluated with a series of liquid extractions that dissolve progressively less soluble phases and electron microbe identification of mineral phases. In terms of the short-term decrease in U mobility (in decreasing order), NH3, NaOH mist, CO2, HCl mist, and Fe(III) mist showed 20% to 35% change in U surface phases. The two reductive gas treatments (H2S and SO2) showed little change. For long-term decrease in U transport, mineral phases created that had low solubility (phosphates, silicates) were desired, so NH3, phosphates (mist and foam delivered), and NaOH mist showed the greatest formation of these minerals.

  5. Quantum state specific reactant preparation in a molecular beam by rapid adiabatic passage

    Science.gov (United States)

    Chadwick, Helen; Hundt, P. Morten; van Reijzen, Maarten E.; Yoder, Bruce L.; Beck, Rainer D.

    2014-01-01

    Highly efficient preparation of molecules in a specific rovibrationally excited state for gas/surface reactivity measurements is achieved in a molecular beam using tunable infrared (IR) radiation from a single mode continuous wave optical parametric oscillator (cw-OPO). We demonstrate that with appropriate focusing of the IR radiation, molecules in the molecular beam crossing the fixed frequency IR field experience a Doppler tuning that can be adjusted to achieve complete population inversion of a two-level system by rapid adiabatic passage (RAP). A room temperature pyroelectric detector is used to monitor the excited fraction in the molecular beam and the population inversion is detected and quantified using IR bleaching by a second IR-OPO. The second OPO is also used for complete population transfer to an overtone or combination vibration via double resonance excitation using two spatially separated RAP processes.

  6. Effects of balneotherapy on the reactants of acute inflammation phase in Ankylosing spondylitis

    Directory of Open Access Journals (Sweden)

    Stamenković Bojana

    2009-01-01

    Full Text Available Introduction. Ankylosing spondylitis (AS is a chronic inflammatory disease that affects sacroiliac joints, spinal column and peripheral joints. Beside medication therapy, physical and balneotherapy play an important role in its complex treatment. Objective. The aim of the research was to establish serum concentrations of C-reactive protein (CRP, α 1-acid glycoprotein (α 1-AGP, ceruloplasmine (CP and erythrocyte sedimentation rate (SE before and after the balneotherapy in ankylosing spondylitis. Methods. The research included 50 AS patients according to the revised New York criteria, of mean age 43 years, who were treated for 14 days on the average at the Clinic for Rheumatology of the Institute 'Niška Banja'. All the patients received medications and balneotherapy (radioactive oligomineral baths, peloid, massage, kinesitherapy; the serum concentrations of CRP, α1-AGP, CP and SE were measured before and after balneotherapy. Serum proteins were determined using original Nor Partigen plates Boehringer. Erythrocyte sedimentation rate was measured by Westergreen method. Balneotherapy was applied individually, intensively or mildly, depending on the AS stage and activity phase. Results. After dosed balneotherapy, a significant decrease in the concentrations of CP (p<0.05, α1-AGP (p<0.01 and CRP (p<0.05 was registered in the serums of AS patients. ESR was not significantly reduced. Conclusion. The research proved that α 1-acid glycoprotein, ceruloplasmine and C-reactive protein represent more sensitive inflammation markers as compared to erythrocyte sedimentation rate. The identification of acute phase reactants is important in the evaluation of dosed balneotherapy efficiency in the treatment of ankylosing spondylitis.

  7. Cord Blood Acute Phase Reactants Predict Early Onset Neonatal Sepsis in Preterm Infants.

    Directory of Open Access Journals (Sweden)

    Leena B Mithal

    Full Text Available Early onset sepsis (EOS is a major cause of morbidity and mortality in preterm infants, yet diagnosis remains inadequate resulting in missed cases or prolonged empiric antibiotics with adverse consequences. Evaluation of acute phase reactant (APR biomarkers in umbilical cord blood at birth may improve EOS detection in preterm infants with intrauterine infection.In this nested case-control study, infants (29.7 weeks gestation, IQR: 27.7-32.2 were identified from a longitudinal cohort with archived cord blood and placental histopathology. Patients were categorized using culture, laboratory, clinical, and antibiotic treatment data into sepsis groups: confirmed sepsis (cEOS, n = 12; presumed sepsis (PS, n = 30; and no sepsis (controls, n = 30. Nine APRs were measured in duplicate from cord blood using commercially available multiplex immunoassays (Bio-Plex Pro™. In addition, placental histopathologic data were linked to biomarker results.cEOS organisms were Escherichia coli, Streptococcus agalactiae, Proteus mirabilis, Haemophilus influenzae and Listeria monocytogenes. C-reactive protein (CRP, serum amyloid A (SAA, haptoglobin (Hp, serum amyloid P and ferritin were significantly elevated in cEOS compared to controls (p<0.01. SAA, CRP, and Hp were elevated in cEOS but not in PS (p<0.01 and had AUCs of 99%, 96%, and 95% respectively in predicting cEOS. Regression analysis revealed robust associations of SAA, CRP, and Hp with EOS after adjustment for covariates. Procalcitonin, fibrinogen, α-2-macroglobulin and tissue plasminogen activator were not significantly different across groups. Placental acute inflammation was associated with APR elevation and was present in all cEOS, 9 PS, and 17 control infants.This study shows that certain APRs are elevated in cord blood of premature infants with EOS of intrauterine origin. SAA, CRP, and Hp at birth have potential diagnostic utility for risk stratification and identification of infants with EOS.

  8. Effects of ligand substitution on the excited state dynamics of the Ru(dcbpy)(CO){sub 2}I{sub 2} complex

    Energy Technology Data Exchange (ETDEWEB)

    Lehtovuori, Viivi; Kallioinen, Jani; Myllyperkioe, Pasi; Haukka, Matti; Korppi-Tommola, Jouko

    2003-11-15

    Spectroscopic evidence suggest [PCCP 3 (2001) 1992] that illumination with visible light of the [trans-I-Ru(dcbpy)(CO){sub 2}I{sub 2}] (dcbpy4,4{sup '}-dicarboxy-2,2{sup '}-bipyridine) complex in solution induces dissociation of a CO group followed by reorganization of the ligands and attachment of a solvent molecule. In the present study, we report results on excited state dynamics of this ruthenium complex and its photoproduct. Femtosecond transient absorption measurements reveal dominance of excited state absorption of the reactant and the photoproduct [cis-I-Ru(dcbpy)(CO)(Sol)I{sub 2}] (Sol=ethanol or acetonitrile) in the visible spectral region. The time-resolved measurements for the reactant at 77 K indicate interligand charge transfer from mixed Ru-I states to empty dcbpy orbitals. For the photoproduct, no such transfer was observed. In both complexes recovery from the lowest energy excited triplet state to the ground state occurs via two channels: radiative relaxation and a parallel barrier controlled non-radiative relaxation. The barrier is much higher in the reactant (about 850 cm{sup -1}) than in the product. A combination of DFT and ZINDO/CI calculations was used to estimate excited singlet and triplet spectra of the reactant and the product molecules. Calculated singlet-triplet difference spectra qualitatively match the observed transient spectra 500 fs after excitation supporting the idea that observed excited state relaxation occurs from the triplet states in both complexes.

  9. Evaluation of the effect of reactant gases mass flow rates on power density in a polymer electrolyte membrane fuel cell

    Science.gov (United States)

    Kahveci, E. E.; Taymaz, I.

    2018-03-01

    In this study it was experimentally investigated the effect of mass flow rates of reactant gases which is one of the most important operational parameters of polymer electrolyte membrane (PEM) fuel cell on power density. The channel type is serpentine and single PEM fuel cell has an active area of 25 cm2. Design-Expert 8.0 (trial version) was used with four variables to investigate the effect of variables on the response using. Cell temperature, hydrogen mass flow rate, oxygen mass flow rate and humidification temperature were selected as independent variables. In addition, the power density was used as response to determine the combined effects of these variables. It was kept constant cell and humidification temperatures while changing mass flow rates of reactant gases. From the results an increase occurred in power density with increasing the hydrogen flow rates. But oxygen flow rate does not have a significant effect on power density within determined mass flow rates.

  10. Detailed high-resolution three-dimensional simulations of OMEGA separated reactants inertial confinement fusion experiments

    Energy Technology Data Exchange (ETDEWEB)

    Haines, Brian M., E-mail: bmhaines@lanl.gov; Fincke, James R.; Shah, Rahul C.; Boswell, Melissa; Fowler, Malcolm M.; Gore, Robert A.; Hayes-Sterbenz, Anna C.; Jungman, Gerard; Klein, Andreas; Rundberg, Robert S.; Steinkamp, Michael J.; Wilhelmy, Jerry B. [Los Alamos National Laboratory, MS T087, Los Alamos, New Mexico 87545 (United States); Grim, Gary P. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Forrest, Chad J.; Silverstein, Kevin; Marshall, Frederic J. [Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623 (United States)

    2016-07-15

    We present results from the comparison of high-resolution three-dimensional (3D) simulations with data from the implosions of inertial confinement fusion capsules with separated reactants performed on the OMEGA laser facility. Each capsule, referred to as a “CD Mixcap,” is filled with tritium and has a polystyrene (CH) shell with a deuterated polystyrene (CD) layer whose burial depth is varied. In these implosions, fusion reactions between deuterium and tritium ions can occur only in the presence of atomic mix between the gas fill and shell material. The simulations feature accurate models for all known experimental asymmetries and do not employ any adjustable parameters to improve agreement with experimental data. Simulations are performed with the RAGE radiation-hydrodynamics code using an Implicit Large Eddy Simulation (ILES) strategy for the hydrodynamics. We obtain good agreement with the experimental data, including the DT/TT neutron yield ratios used to diagnose mix, for all burial depths of the deuterated shell layer. Additionally, simulations demonstrate good agreement with converged simulations employing explicit models for plasma diffusion and viscosity, suggesting that the implicit sub-grid model used in ILES is sufficient to model these processes in these experiments. In our simulations, mixing is driven by short-wavelength asymmetries and longer-wavelength features are responsible for developing flows that transport mixed material towards the center of the hot spot. Mix material transported by this process is responsible for most of the mix (DT) yield even for the capsule with a CD layer adjacent to the tritium fuel. Consistent with our previous results, mix does not play a significant role in TT neutron yield degradation; instead, this is dominated by the displacement of fuel from the center of the implosion due to the development of turbulent instabilities seeded by long-wavelength asymmetries. Through these processes, the long

  11. Kinetics of the glucose/glycine Maillard reaction pathways: influences of pH and reactant initial concentrations

    NARCIS (Netherlands)

    Martins, S.I.F.S.; Boekel, van M.A.J.S.

    2005-01-01

    A previously proposed kinetic model for the glucose/glycine Maillard reaction pathways has been validated by changing the initial pH (4.8, 5.5, 6.0, 6.8 and 7.5) of the reaction and reactant initial concentrations (1:2 and 2:1 molar ratios were compared to the 1:1 ratio). The model consists of 10

  12. Electron-excited molecule interactions

    International Nuclear Information System (INIS)

    Christophorou, L.G.; Tennessee Univ., Knoxville, TN

    1991-01-01

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

  13. Synthesis of nanoparticles from malleable and ductile metals using powder-free, reactant-assisted mechanical attrition.

    Science.gov (United States)

    McMahon, Brandon W; Perez, Jesus Paulo L; Yu, Jiang; Boatz, Jerry A; Anderson, Scott L

    2014-11-26

    A reactant-assisted mechanochemical method was used to produce copious nanoparticles from malleable/ductile metals, demonstrated here for aluminum, iron, and copper. The milling media is intentionally degraded via a reactant-accelerated wear process, where the reactant aids particle production by binding to the metal surfaces, enhancing particle production, and reducing the tendency toward mechanochemical (cold) welding. The mechanism is explored by comparing the effects of different types of solvents and solvent mixtures on the amount and type of particles produced. Particles were functionalized with oleic acid to aid in particle size separation, enhance dispersion in hydrocarbon solvents, and protect the particles from oxidation. For aluminum and iron, the result is air-stable particles, but for copper, the suspended particles are found to dissolve when exposed to air. Characterization was performed using electron microscopy, dynamic light scattering, Fourier transform infrared spectroscopy, solid state nuclear magnetic resonance, and X-ray photoelectron spectroscopy. Density functional theory was used to examine the nature of carboxylic acid binding to the aluminum surface, confirming the dominance of bridging bidentate binding.

  14. The influence of tertiary butyl hydrazine as a co-reactant on the atomic layer deposition of silver

    Energy Technology Data Exchange (ETDEWEB)

    Golrokhi, Zahra; Marshall, Paul A.; Romani, Simon [Centre for Materials and Structures, School of Engineering,The University of Liverpool, Liverpool L69 3GH (United Kingdom); Rushworth, Simon [EpiValence, The Wilton Centre, Redcar, Cleveland, TS10 4RF (United Kingdom); Chalker, Paul R. [Centre for Materials and Structures, School of Engineering,The University of Liverpool, Liverpool L69 3GH (United Kingdom); Potter, Richard J., E-mail: rjpott@liverpool.ac.uk [Centre for Materials and Structures, School of Engineering,The University of Liverpool, Liverpool L69 3GH (United Kingdom)

    2017-03-31

    Highlights: • We demonstrate metallic silver growth by direct liquid injection thermal ALD. • A substituted hydrazine is used as a powerful reducing agent for the first time. • The hydrazine extends the ALD temperature window compared with alcohol. • Hydrazine promotes a more planar growth mode compared to alcohol. • Film adhesion is improved using hydrazine compared with alcohol. - Abstract: Ultra-thin conformal silver films are the focus of development for applications such as anti-microbial surfaces, optical components and electronic devices. In this study, metallic silver films have been deposited using direct liquid injection thermal atomic layer deposition (ALD) using (hfac)Ag(1,5-COD) ((hexafluoroacetylacetonato)silver(I)(1,5-cyclooctadiene)) as the metal source and tertiary butyl hydrazine (TBH) as a co-reactant. The process provides a 23 °C wide ‘self-limiting’ ALD temperature window between 105 and 128 °C, which is significantly wider than is achievable using alcohol as a co-reactant. A mass deposition rate of ∼20 ng/cm{sup 2}/cycle (∼0.18 Å/cycle) is observed under self-limiting growth conditions. The resulting films are crystalline metallic silver with a near planar film-like morphology which are electrically conductive. By extending the temperature range of the ALD window by the use of TBH as a co-reactant, it is envisaged that the process will be exploitable in a range of new low temperature applications.

  15. Bibliography of atomic and molecular excitation in heavy particle collisions, 1950--1975

    International Nuclear Information System (INIS)

    Hawthorne, S.W.; Thomas, E.W.; Barnett, C.F.; Crandall, D.H.; Gilbody, H.B.; Kirkpatrick, M.I.; McDaniel, E.W.; Phaneuf, R.A.

    1979-02-01

    This annotated bibliography lists published work on atomic and molecular excitation in heavy particle collisions for the period 1950 to 1975. Sources include scientific journals, abstract compilations, conference proceedings, books, and reports. The bibliography is arranged alphabetically by author. Each entry indicates whether the work was experimental or theoretical, what energy range was covered, and what reactants were investigated. Following the bibliographical listing are indexes of reactions and authors

  16. Nonorthogonal orbital based N-body reduced density matrices and their applications to valence bond theory. I. Hamiltonian matrix elements between internally contracted excited valence bond wave functions

    Science.gov (United States)

    Chen, Zhenhua; Chen, Xun; Wu, Wei

    2013-04-01

    In this series, the n-body reduced density matrix (n-RDM) approach for nonorthogonal orbitals and their applications to ab initio valence bond (VB) methods are presented. As the first paper of this series, Hamiltonian matrix elements between internally contracted VB wave functions are explicitly provided by means of nonorthogonal orbital based RDM approach. To this end, a more generalized Wick's theorem, called enhanced Wick's theorem, is presented both in arithmetical and in graphical forms, by which the deduction of expressions for the matrix elements between internally contracted VB wave functions is dramatically simplified, and the matrix elements are finally expressed in terms of tensor contractions of electronic integrals and n-RDMs of the reference VB self-consistent field wave function. A string-based algorithm is developed for the purpose of evaluating n-RDMs in an efficient way. Using the techniques presented in this paper, one is able to develop new methods and efficient algorithms for nonorthogonal orbital based many-electron theory much easier than by use of the first quantized formulism.

  17. Polymeric Electrolyte Membrane Photoelectrochemical (PEM-PEC Cell with a Web of Titania Nanotube Arrays as Photoanode and Gaseous Reactants

    Directory of Open Access Journals (Sweden)

    Tsampas M.N.

    2017-01-01

    Photoanodes of titania nanotube arrays, TNTAs, were developed, for the first time, on a Ti-web of microfiber substrates, by electrochemical anodization. The performance of TNTAs/Ti-web photoanodes were evaluated in both gaseous and liquid reactants. Due to the presence of reliable reference electrode in gas phase direct comparison of the results was possible. Gas phase operation with He or Air as carrier gases and only 2.5% of water content exhibits very promising photoefficiency in comparison with conventional PEC cells.

  18. Excited charmed mesons

    International Nuclear Information System (INIS)

    Butler, J.N.; Shukla, S.

    1995-05-01

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

  19. Portable vibration exciter

    Science.gov (United States)

    Beecher, L. C.; Williams, F. T.

    1970-01-01

    Gas-driven vibration exciter produces a sinusoidal excitation function controllable in frequency and in amplitude. It allows direct vibration testing of components under normal loads, removing the possibility of component damage due to high static pressure.

  20. Multi-frequency excitation

    KAUST Repository

    Younis, Mohammad I.

    2016-01-01

    Embodiments of multi-frequency excitation are described. In various embodiments, a natural frequency of a device may be determined. In turn, a first voltage amplitude and first fixed frequency of a first source of excitation can be selected

  1. Kinetic studies following state-selective laser excitation: Progress report, March 15, 1988--March 14, 1989

    International Nuclear Information System (INIS)

    Keto, J.W.

    1988-11-01

    The objective of this contract is the study of state-to-state, electronic energy transfer reactions following two-photon laser excitation. We have chosen to study reactions of Xe 5p 5 np because of their relevance to the XeCl excimer laser. We are studying deactivation reactions in collisions with heavy atoms such as Ar, Kr, and Xe and reactive collisions with chlorides. The reactants are excited by multiphoton laser absorption. Product channels are observed by their fluorescence, or by laser induced fluorescence using a second color laser. Reaction rates are measured by observing the time dependent decay of signals from reactant and product channels. In addition we measure interaction potentials of the reactants by laser spectroscopy where the laser induced fluorescence or ionization is measured as a function of laser wavelength (excitation spectra) or by measuring fluorescence spectra at fixed laser frequencies with monochromators. The spectra are obtained in the form of either lineshapes or individual lines from rovibrational transitions of bound states. 11 refs. 4 figs., 3 tabs

  2. Metal Palladium Dispersed Inside Macroporous Ion-Exchange Resins: Textural Characterization and Accessibility to Gaseou Reactants

    Czech Academy of Sciences Publication Activity Database

    Biffis, A.; Jeřábek, Karel; D'Archivio, A. A.; Galantini, L.; Corain, B.

    2000-01-01

    Roč. 130, - (2000), s. 2327-2332 ISSN 0167-2991. [International Congress on Catalysis /12./. Granada, 09.07.2000-14.07.2000] Institutional research plan: CEZ:AV0Z4072921 Keywords : metal palladium * dispersed * ion-exchange resins Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 0.513, year: 2000

  3. Serum levels of chicken mannan-binding lectin (MBL) during virus infections; indication that chicken MBL is an acute phase reactant

    DEFF Research Database (Denmark)

    Nielsen, O.L.; Jensenius, J. C.; Jørgensen, Poul Henrik

    1999-01-01

    Mannan-binding lectin (MBL) is a serum collectin which is believed to be an opsonin of the innate immune defence against various microorganisms. MBL is a minor acute phase reactant in man. We investigated the concentration of serum MBL in chickens infected with infectious bronchitis virus (IBV...... levels returned to normal values 6-10 days after infection. The results indicated that MBL is a minor acute phase reactant in chickens....

  4. The general theory of multistage geminate reactions of isolated pairs of reactants. III. Two-stage reversible dissociation in geminate reaction A + A↔C↔B + B

    Energy Technology Data Exchange (ETDEWEB)

    Kipriyanov, Alexey A.; Kipriyanov, Alexander A.; Doktorov, Alexander B. [Voevodsky Institute of Chemical Kinetics and Combustion, Siberian Branch of the Russian Academy of Sciences, Novosibirsk 630090, Russia and Novosibirsk State University, Novosibirsk 630090 (Russian Federation)

    2016-04-14

    Specific two-stage reversible reaction A + A↔C↔B + B of the decay of species C reactants by two independent transition channels is considered on the basis of the general theory of multistage reactions of isolated pairs of reactants. It is assumed that at the initial instant of time, the reacting system contains only reactants C. The employed general approach has made it possible to consider, in the general case, the inhomogeneous initial distribution of reactants, and avoid application of model concepts of a reaction system structure (i.e., of the structure of reactants and their molecular mobility). Slowing of multistage reaction kinetics as compared to the kinetics of elementary stages is established and physically interpreted. To test approximations (point approximation) used to develop a universal kinetic law, a widely employed specific model of spherical particles with isotropic reactivity diffusing in solution is applied. With this particular model as an example, ultimate kinetics of chemical conversion of reactants is investigated. The question concerning the depths of chemical transformation at which long-term asymptotes are reached is studied.

  5. The general theory of multistage geminate reactions of isolated pairs of reactants. III. Two-stage reversible dissociation in geminate reaction A + A ↔ C ↔ B + B.

    Science.gov (United States)

    Kipriyanov, Alexey A; Kipriyanov, Alexander A; Doktorov, Alexander B

    2016-04-14

    Specific two-stage reversible reaction A + A ↔ C ↔ B + B of the decay of species C reactants by two independent transition channels is considered on the basis of the general theory of multistage reactions of isolated pairs of reactants. It is assumed that at the initial instant of time, the reacting system contains only reactants C. The employed general approach has made it possible to consider, in the general case, the inhomogeneous initial distribution of reactants, and avoid application of model concepts of a reaction system structure (i.e., of the structure of reactants and their molecular mobility). Slowing of multistage reaction kinetics as compared to the kinetics of elementary stages is established and physically interpreted. To test approximations (point approximation) used to develop a universal kinetic law, a widely employed specific model of spherical particles with isotropic reactivity diffusing in solution is applied. With this particular model as an example, ultimate kinetics of chemical conversion of reactants is investigated. The question concerning the depths of chemical transformation at which long-term asymptotes are reached is studied.

  6. Study of excitation of low energy for the low-temperature internal friction in the metallic glass Co35Y65

    International Nuclear Information System (INIS)

    Jin, Z.; Zou, X.; Liu, F.

    1990-01-01

    Based on the unified theory of low-frequency fluctuation, dissipation, and relaxation processes, we studied the broad and asymmetric low-temperature internal friction peak of the metallic glass Co 35 Y 65 . This theory, which differs from that of distributed relaxation times, involves only a single relaxation time τ P . By this theory, the calculated infrared-divergence exponent n=0.62, characteristic relaxation time τ ∞ =2x10 -14 s, actual activation energy E A =0.2 eV, and apparent activation energy E * A =0.52 eV. They are in agreement with available experimental results (τ ∞ =2.2x10 -14 s, E A =0.25 eV, and E * A =0.56 eV). Since the composition is very close to that of the intermetallics CoY 2 , the chemical short range order exists partly in the metallic glass Co 35 Y 65 . We notice from the behavior of this peak that it is not caused by the motion of gas atoms dissolved in the sample. From the much smaller radius of a Co atom compared with that of Y, we suggest this peak results from migration of Co atoms to neighboring vacancy with infrared divergence

  7. Elementary excitations in nuclei

    International Nuclear Information System (INIS)

    Lemmer, R.H.

    1987-01-01

    The role of elementary quasi-particle and quasi-hole excitations is reviewed in connection with the analysis of data involving high-lying nuclear states. This article includes discussions on: (i) single quasi-hole excitations in pick-up reactions, (ii) the formation of single quasi-hole and quasi-particle excitations (in different nuclei) during transfer reactions, followed by (iii) quasi-particle quasi-hole excitations in the same nucleus that are produced by photon absorption. Finally, the question of photon absorption in the vicinity of the elementary Δ resonance is discussed, where nucleonic as well as nuclear degrees of freedom can be excited

  8. Multi-frequency excitation

    KAUST Repository

    Younis, Mohammad I.

    2016-03-10

    Embodiments of multi-frequency excitation are described. In various embodiments, a natural frequency of a device may be determined. In turn, a first voltage amplitude and first fixed frequency of a first source of excitation can be selected for the device based on the natural frequency. Additionally, a second voltage amplitude of a second source of excitation can be selected for the device, and the first and second sources of excitation can be applied to the device. After applying the first and second sources of excitation, a frequency of the second source of excitation can be swept. Using the methods of multi- frequency excitation described herein, new operating frequencies, operating frequency ranges, resonance frequencies, resonance frequency ranges, and/or resonance responses can be achieved for devices and systems.

  9. a simple a simple excitation control excitation control excitation

    African Journals Online (AJOL)

    eobe

    field voltages determined follow a simple quadratic relationship that offer a very simple control scheme, dependent on only the stator current. Keywords: saturated reactances, no-load field voltage, excitation control, synchronous generators. 1. Introduction. Introduction. Introduction. The commonest generator in use today is ...

  10. International

    International Nuclear Information System (INIS)

    Anon.

    1997-01-01

    This rubric reports on 10 short notes about international economical facts about nuclear power: Electricite de France (EdF) and its assistance and management contracts with Eastern Europe countries (Poland, Hungary, Bulgaria); Transnuclear Inc. company (a 100% Cogema daughter company) acquired the US Vectra Technologies company; the construction of the Khumo nuclear power plant in Northern Korea plays in favour of the reconciliation between Northern and Southern Korea; the delivery of two VVER 1000 Russian reactors to China; the enforcement of the cooperation agreement between Euratom and Argentina; Japan requested for the financing of a Russian fast breeder reactor; Russia has planned to sell a floating barge-type nuclear power plant to Indonesia; the control of the Swedish reactor vessels of Sydkraft AB company committed to Tractebel (Belgium); the renewal of the nuclear cooperation agreement between Swiss and USA; the call for bids from the Turkish TEAS electric power company for the building of the Akkuyu nuclear power plant answered by three candidates: Atomic Energy of Canada Limited (AECL), Westinghouse (US) and the French-German NPI company. (J.S.)

  11. Spirals in a reaction-diffusion system: Dependence of wave dynamics on excitability

    Science.gov (United States)

    Mahanta, Dhriti; Das, Nirmali Prabha; Dutta, Sumana

    2018-02-01

    A detailed study of the effects of excitability of the Belousov-Zhabotinsky (BZ) reaction on spiral wave properties has been carried out. Using the Oregonator model, we explore the various regimes of wave activity, from sustained oscillations to wave damping, as the system undergoes a Hopf bifurcation, that is achieved by varying the excitability parameter, ɛ . We also discover a short range of parameter values where random oscillations are observed. With an increase in the value of ɛ , the frequency of the wave decreases exponentially, as the dimension of the spiral core expands. These numerical results are confirmed by carrying out experiments in thin layers of the BZ system, where the excitability is changed by varying the concentrations of the reactant species. Effect of reactant concentrations on wave properties like time period and wavelength are also explored in detail. Drifting and meandering spirals are found in the parameter space under investigation, with the excitability affecting the tip trajectory in a way predicted by the numerical studies. This study acts as a quantitative evidence of the relationship between the excitability parameter, ɛ , and the substrate concentrations.

  12. Spirals in a reaction-diffusion system: Dependence of wave dynamics on excitability.

    Science.gov (United States)

    Mahanta, Dhriti; Das, Nirmali Prabha; Dutta, Sumana

    2018-02-01

    A detailed study of the effects of excitability of the Belousov-Zhabotinsky (BZ) reaction on spiral wave properties has been carried out. Using the Oregonator model, we explore the various regimes of wave activity, from sustained oscillations to wave damping, as the system undergoes a Hopf bifurcation, that is achieved by varying the excitability parameter, ε. We also discover a short range of parameter values where random oscillations are observed. With an increase in the value of ε, the frequency of the wave decreases exponentially, as the dimension of the spiral core expands. These numerical results are confirmed by carrying out experiments in thin layers of the BZ system, where the excitability is changed by varying the concentrations of the reactant species. Effect of reactant concentrations on wave properties like time period and wavelength are also explored in detail. Drifting and meandering spirals are found in the parameter space under investigation, with the excitability affecting the tip trajectory in a way predicted by the numerical studies. This study acts as a quantitative evidence of the relationship between the excitability parameter, ε, and the substrate concentrations.

  13. The reactants equation of state for the tri-amino-tri-nitro-benzene (TATB) based explosive PBX 9502

    Science.gov (United States)

    Aslam, Tariq D.

    2017-07-01

    The response of high explosives (HEs), due to mechanical and/or thermal insults, is of great importance for both safety and performance. A major component of how an HE responds to these stimuli stems from its reactant equation of state (EOS). Here, the tri-amino-tri-nitro-benzene based explosive PBX 9502 is investigated by examining recent experiments. Furthermore, a complete thermal EOS is calibrated based on the functional form devised by Wescott, Stewart, and Davis [J. Appl. Phys. 98, 053514 (2005)]. It is found, by comparing to earlier calibrations, that a variety of thermodynamic data are needed to sufficiently constrain the EOS response over a wide range of thermodynamic state space. Included in the calibration presented here is the specific heat as a function of temperature, isobaric thermal expansion, and shock Hugoniot response. As validation of the resulting model, isothermal compression and isentropic compression are compared with recent experiments.

  14. On isospin excitation energy

    International Nuclear Information System (INIS)

    Li Wenfei; Zhang Fengshou; Chen Liewen

    2001-01-01

    Within the framework of Hartree-Fock theory using the extended Skyrme effective interaction, the isospin excitation energy as a function of relative neutron excess δ was investigated at different temperatures and densities. It was found that the isospin excitation energy decreased with the increment of temperature and/or the decrement of density. The authors pointed out that the decrement of isospin excitation energy was resulted from the weakening of quantum effect with increment of temperature and/or decrement of density. Meanwhile, the relationship between the isospin excitation energy and the symmetry energy was discussed and found that the symmetry energy was just a part of the isospin excitation energy. With increasing temperature and decreasing density, the contribution of the symmetry energy to the isospin excitation energy becomes more and more important. The isospin excitation energy as a function of relative neutron excess was also investigated using different potential parameters. The results shows that the isospin excitation energy is almost independent of the incompressibility and the effective mass, but strongly depends on the symmetry energy strength coefficient, which indicates that it is possible to extract the symmetry energy of the nuclear equation of state by investigating the isospin excitation energy in experiments

  15. Excited states 2

    CERN Document Server

    Lim, Edward C

    2013-01-01

    Excited States, Volume 2 is a collection of papers that deals with molecules in the excited states. The book describes the geometries of molecules in the excited electronic states. One paper describes the geometries of a diatomic molecule and of polyatomic molecules; it also discusses the determination of the many excited state geometries of molecules with two, three, or four atoms by techniques similar to diatomic spectroscopy. Another paper introduces an ordered theory related to excitons in pure and mixed molecular crystals. This paper also presents some experimental data such as those invo

  16. Excited states v.6

    CERN Document Server

    Lim, Edward C

    1982-01-01

    Excited States, Volume 6 is a collection of papers that discusses the excited states of molecules. The first paper discusses the linear polyene electronic structure and potential surfaces, considering both the theoretical and experimental approaches in such electronic states. This paper also reviews the theory of electronic structure and cites some experimental techniques on polyene excitations, polyene spectroscopic phenomenology, and those involving higher states of polyenes and their triplet states. Examples of these experimental studies of excited states involve the high-resolution one-pho

  17. The effect of layer thickness and composition on the kinetics of solid state reactions in the niobium-selenium system studied using superlattice reactants

    International Nuclear Information System (INIS)

    Fukuto, M.; Kevan, S.D.

    1997-01-01

    The ability to form an amorphous reaction intermediate by the low temperature interdiffusion of a modulated elemental reactant is shown to be a function of the overall composition as well as elemental layer thicknesses in the niobium-selenium system. For niobium-rich reactants, an amorphous reaction intermediate was observed to form upon low temperature annealing of reactants with modulation thicknesses less than 60 A. Further annealing of the amorphous intermediates led to the crystallization of Nb 2 Se, Nb 5 Se 4 or Nb 3 Se 4 depending upon the overall composition of the amorphous intermediate. Modulated elemental reactants with overall compositions containing more than two-thirds selenium were found to heterogeneously nucleate NbSe 2 at the reacting interfaces. The formation of the thermodynamically expected compounds Nb 2 Se 3 , NbSe 3 , and Nb 2 Se 9 at their respective compositions required extended high temperature annealing to react the dichalcogenide with the remaining elemental reactants. A striking difference between the evolution of the low angle diffraction patterns in these two composition regimes suggests the differences in the reaction kinetics result from a composition dependence of the diffusion coefficients. (orig.)

  18. Electrogenerated chemiluminescence of tris(2,2' bipyridine)ruthenium(II) using common biological buffers as co-reactant, pH buffer and supporting electrolyte.

    Science.gov (United States)

    Kebede, Noah; Francis, Paul S; Barbante, Gregory J; Hogan, Conor F

    2015-11-07

    A series of aliphatic tertiary amines (HEPES, POPSO, EPPS and BIS-TRIS) commonly used to buffer the pH in biological experiments, were examined as alternative, non-toxic co-reactants for the electrogenerated chemiluminescence (ECL) of tris(2,2'-bipyridine)ruthenium(ii) ([Ru(bpy)3](2+)). These were found to be very attractive as "multi-tasking" reagents, serving not only as co-reactants, but also fulfiling the roles of pH buffer and supporting electrolyte within an aqueous environment; thus significantly simplifying the overall ECL analysis. Sub-nanomolar detection limits were obtained for [Ru(bpy)3](2+) in the presence of BIS-TRIS, making this species an valuable option for co-reactant ECL-based bioanalytical applications.

  19. Use of periodic variations of reactant concentrations in time resolved ftir studies of CO oxidation on Pd/ZrO{sub 2} catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Ortelli, E; Wokaun, A [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1999-08-01

    Sine wave modulation of feed concentrations was used to induce dynamic variations in the concentrations of products, intermediates and reactants, which were monitored in a diffuse reflectance FTIR (DRIFT) cell. The phase shift {Delta}{phi} between the external perturbation of the feed and the signals of products, intermediates and reactants was examined in dependence on the modulation frequency {omega}. Reaction constants of a simplified model mechanism were estimated for a Pd{sub 25}Zr{sub 75} based catalyst for CO oxidation. (author) 1 fig., 2 refs.

  20. Kinetic studies following state-selective laser excitation: Annual performance report for the period March 15, 1987-March 14, 1988

    International Nuclear Information System (INIS)

    Keto, J.W.

    1987-11-01

    The objective of this contract is the study of state-to-state, electronic energy transfer reactions following two-photon laser excitation. We have specifically been studying reactions of Xe 5p 5 6p because of their relevance to the XeCl excimer laser. We are studying deactivation reactions in collisions with heavy atoms such as Ar, Kr, and Xe and reactive collisions with chlorides. The reactants are excited by multiphoton laser absorption. Product channels are observed by their fluorescence, or in experiments in the coming months by laser induced fluorescence using a second color laser. Reaction rates are measured by observing the time dependent decay of signals from reactant and product channels. In addition we measure interaction potentials of the reactants by laser spectroscopy where the laser induced fluorescence or ionization is measured as a function of laser wavelength (excitation spectra) or by measuring fluorescence spectra at fixed laser frequencies with monochromators. The spectra are obtained in the form of either lineshapes or individual lines from rovibrational transitions of bound states. 4 figs

  1. Atomic layer deposition of Ru thin film using N{sub 2}/H{sub 2} plasma as a reactant

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Tae Eun [Busan Center, Korea Basic Science Institute, 1275 Jisadong, Gangseogu, Busan, 618-230 (Korea, Republic of); Mun, Ki-Yeung; Choi, Sang-Kyung; Park, Ji-Yoon [School of Materials Science and Engineering Yeungnam University 214-1, Dae-dong, Gyeongsan-si, Gyeongsangbuk-do, 712-749 (Korea, Republic of); Kim, Soo-Hyun, E-mail: soohyun@ynu.ac.kr [School of Materials Science and Engineering Yeungnam University 214-1, Dae-dong, Gyeongsan-si, Gyeongsangbuk-do, 712-749 (Korea, Republic of); Cheon, Taehoon [Center for Core Research Facilities, Daegu Gyeongbuk Institute of Science and Technology, Sang-ri, Hyeonpung-myeon, Dalseong-gun, Daegu (Korea, Republic of); Kim, Woo Kyoung [School of Chemical Engineering, Yeungnam University, 214-1, Dae-dong, Gyeongsan-si, Gyeongsangbuk-do, 712-749 (Korea, Republic of); Lim, Byoung-Yong; Kim, Sunjung [School of Materials Science and Engineering, University of Ulsan, Mugeo-dong, Nam-go, Ulsan, 680-749 (Korea, Republic of)

    2012-07-31

    Ruthenium (Ru) thin films were grown by atomic layer deposition using IMBCHRu [({eta}6-1-Isopropyl-4-MethylBenzene)({eta}4-CycloHexa-1,3-diene)Ruthenium(0)] as a precursor and a nitrogen-hydrogen mixture (N{sub 2}/H{sub 2}) plasma as a reactant, at the substrate temperature of 270 Degree-Sign C. In the wide range of the ratios of N{sub 2} and total gas flow rates (fN{sub 2}/N{sub 2} + H{sub 2}) from 0.12 to 0.70, pure Ru films with negligible nitrogen incorporation of 0.5 at.% were obtained, with resistivities ranging from {approx} 20 to {approx} 30 {mu} Ohm-Sign cm. A growth rate of 0.057 nm/cycle and negligible incubation cycle for the growth on SiO{sub 2} was observed, indicating the fast nucleation of Ru. The Ru films formed polycrystalline and columnar grain structures with a hexagonal-close-packed phase. Its resistivity was dependent on the crystallinity, which could be controlled by varying the deposition parameters such as plasma power and pulsing time. Cu was electroplated on a 10-nm-thick Ru film. Interestingly, it was found that the nitrogen could be incorporated into Ru at a higher reactant gas ratio of 0.86. The N-incorporated Ru film ({approx} 20 at.% of N) formed a nanocrystalline and non-columnar grain structure with the resistivity of {approx} 340 {mu} Ohm-Sign cm. - Highlights: Black-Right-Pointing-Pointer Atomic layer deposition (ALD) of Ru and N-incorporated Ru film using N{sub 2}/H{sub 2} plasma. Black-Right-Pointing-Pointer The growth rate of 0.057 nm/cycle and negligible incubation cycle. Black-Right-Pointing-Pointer A low resistivity of Ru ({approx} 16.5 {mu} Ohm-Sign cm) at the deposition temperature of 270 Degree-Sign C. Black-Right-Pointing-Pointer Electroplating of Cu on a 10-nm-thick ALD-Ru film.

  2. Harmonic excitations in quasicrystals

    International Nuclear Information System (INIS)

    Luck, J.M.

    1986-03-01

    The harmonic excitations (phonons) of quasicrystals are studied in a simple one-dimensional model. The spectrum is a Cantor set, which exhibits selfsimilarity properties. The eigenstates are generically ''critical'', i.e. neither extended nor localized

  3. Radio frequency plasma excitation

    International Nuclear Information System (INIS)

    Burden, M.St.J.; Cross, K.B.

    1979-01-01

    An investigation into the use of rf sputtering for ion cleaning of insulating substrates before ion plating is reported. Initial experiments consisted of sputtering metals with rf power followed by the deposition of copper onto glass slides using rf plasma excitation and biasing supply. It was found that good quality films were obtained by rf ion plating onto plastics with excellent adhesion over a wide operating pressure range. A block schematic of the rf plasma excitation system is shown. (UK)

  4. High energy nuclear excitations

    International Nuclear Information System (INIS)

    Gogny, D.; Decharge, J.

    1983-09-01

    The main purpose of this talk is to see whether a simple description of the nuclear excitations permits one to characterize some of the high energy structures recently observed. The discussion is based on the linear response to different external fields calculated using the Random Phase Approximation. For those structure in heavy ion collisions at excitation energies above 50 MeV which cannot be explained with such a simple approach, we discuss a possible mechanism for this heavy ion scattering

  5. Experimental advances and preliminary mathematical modeling of the Swiss-roll mixed-reactant direct borohydride fuel cell

    Science.gov (United States)

    Aziznia, Amin; Oloman, Colin W.; Gyenge, Előd L.

    2014-11-01

    The Swiss-roll single-cell mixed reactant (SR-MRFC) borohydride - oxygen fuel cell equipped with Pt/carbon cloth 3D anode and either MnO2 or Ag gas-diffusion cathodes is investigated by a combination of experimental studies and preliminary mathematical modeling of the polarization curve. We investigate the effects of four variables: cathode side metallic mesh fluid distributor, separator type (Nafion 112® vs. Viledon®), cathode catalyst (MnO2 vs. Ag), and the hydrophilic pore volume fraction of the gas-diffusion cathode. Using a two-phase feed of alkaline borohydride solution (1 M NaBH4 - 2 M NaOH) and O2 gas in an SR-MRFC equipped with Pt/C 3D anode, MnO2 gas diffusion cathode, Viledon® porous diaphragm, expanded mesh cathode-side fluid distributor, the maximum superficial power density is 2230 W m-2 at 323 K and 105 kPa(abs). The latter superficial power density is almost 3.5 times higher than our previously reported superficial power density for the same catalyst combinations. Furthermore, with a Pt anode and Ag cathode catalyst combination, a superficial power density of 2500 W m-2 is achieved with superior performance durability compared to the MnO2 cathode. The fuel cell results are substantiated by impedance spectroscopy analysis and preliminary mathematical model predictions based on mixed potential theory.

  6. Characterization of Cr-rich Cr-Sb multilayer films: Syntheses of a new metastable phase using modulated elemental reactants

    International Nuclear Information System (INIS)

    Regus, Matthias; Mankovsky, Sergiy; Polesya, Svitlana; Kuhn, Gerhard; Ditto, Jeffrey; Schürmann, Ulrich; Jacquot, Alexandre; Bartholomé, Kilian; Näther, Christian; Winkler, Markus; König, Jan D.; Böttner, Harald; Kienle, Lorenz; Johnson, David C.; Ebert, Hubert; Bensch, Wolfgang

    2015-01-01

    The new metastable compound Cr 1+x Sb with x up to 0.6 has been prepared via a thin film approach using modulated elemental reactants and investigated by in-situ X-ray reflectivity, X-ray diffraction, differential scanning calorimetry, energy dispersive X-ray analysis as well as transmission electron microscopy and atomic force microscopy. The new Cr-rich antimonide crystallizes in a structure related to the Ni 2 In-type structure, where the crystallographic position (1/3, 2/3, 3/4) is partially occupied by excess Cr. The elemental layers of the pristine material interdiffused significantly before Cr 1+x Sb crystallized. A change in the activation energy was observed for the diffusion process when crystal growth starts. First-principles electronic structure calculations provide insight into the structural stability, magnetic properties and resistivity of Cr 1+x Sb. - Graphical abstract: 1 amorphous multilayered film 2 interdiffused amorphous film 3 metastable crystalline phase 4 thermodynamic stable phase (and by-product). - Highlights: • Interdiffusion of amorphous Cr and Sb occurs before crystallization. • Crystallization of a new metastable phase Cr 1.6 Sb in Ni 2 In-type structure. • The new Cr-rich phase shows half-metallic behavior

  7. Independent Orbiter Assessment (IOA): Assessment of the electrical power generation/power reactant storage and distribution subsystem FMEA/CIL

    Science.gov (United States)

    Ames, B. E.

    1988-01-01

    The results of the Independent Orbiter Assessment (IOA) of the Failure Modes and Effects Analysis (FMEA) and Critical Items List (CIL) is presented. The IOA effort first completed an analysis of the Electrical Power Generation/Power Reactant Storage and Distribution (EPG/PRSD) subsystem hardware, generating draft failure modes and potential critical items. To preserve independence, this analysis was accomplished without reliance upon the results contained within the NASA FMEA/CIL documentation. The IOA results were then compared to the NASA FMEA/CIL baselines with proposed Post 51-L updates included. A resolution of each discrepancy from the comparison is provided through additional analysis as required. The results of that comparison are documented for the Orbiter EPG/PRSD hardware. The comparison produced agreement on all but 27 FMEAs and 9 CIL items. The discrepancy between the number of IOA findings and NASA FMEAs can be partially explained by the different approaches used by IOA and NASA to group failure modes together to form one FMEA. Also, several IOA items represented inner tank components and ground operations failure modes which were not in the NASA baseline.

  8. In situ generation of steam and alkaline surfactant for enhanced oil recovery using an exothermic water reactant (EWR)

    Science.gov (United States)

    Robertson, Eric P

    2011-05-24

    A method for oil recovery whereby an exothermic water reactant (EWR) encapsulated in a water soluble coating is placed in water and pumped into one or more oil wells in contact with an oil bearing formation. After the water carries the EWR to the bottom of the injection well, the water soluble coating dissolves and the EWR reacts with the water to produce heat, an alkali solution, and hydrogen. The heat from the EWR reaction generates steam, which is forced into the oil bearing formation where it condenses and transfers heat to the oil, elevating its temperature and decreasing the viscosity of the oil. The aqueous alkali solution mixes with the oil in the oil bearing formation and forms a surfactant that reduces the interfacial tension between the oil and water. The hydrogen may be used to react with the oil at these elevated temperatures to form lighter molecules, thus upgrading to a certain extent the oil in situ. As a result, the oil can flow more efficiently and easily through the oil bearing formation towards and into one or more production wells.

  9. Solar fuel production in a novel polymeric electrolyte membrane photoelectrochemical (PEM-PEC) cell with a web of titania nanotube arrays as photoanode and gaseous reactants

    NARCIS (Netherlands)

    Stoll, T.; Zafeiropoulos, G.; Tsampas, M. N.

    2016-01-01

    A novel photoelectrochemical (PEC) cell design is proposed and investigated for H-2 production with gaseous reactants. The core of the cell is a membrane electrode assembly (MEA) that consists of a TiO2 nanotube arrays photoanode, a Pt/C cathode, a Pt/C reference electrode and a proton conducting

  10. CATALYST-FREE REACTIONS UNDER SOLVENT-FEE CONDITIONS: MICROWAVE-ASSISTED SYNTHESIS OF HETEROCYCLIC HYDRAZONES BELOW THE MELTING POINT OF NEAT REACTANTS: JOURNAL ARTICLE

    Science.gov (United States)

    NRMRL-CIN-1437 Jeselnik, M., Varma*, R.S., Polanc, S., and Kocevar, M. Catalyst-free Reactions under Solvent-fee Conditions: Microwave-assisted Synthesis of Heterocyclic Hydrazones below the Melting Point of Neat Reactants. Published in: Chemical Communications 18:1716-1717 (200...

  11. Negative ion formation in collisions involving excited alkali atoms

    International Nuclear Information System (INIS)

    Cheret, M.

    1988-01-01

    Ion-pair production is considered as the prototype of the crossing problem between potential energy curves. In general an alkali atom is one of the reactants the other being an halogen, hydrogen atom or molecule. Experimental results are generally analyzed in the framework of the Landau-Zener-Stuekelberg theory, ionization potential and electron affinity, being the most important parameters. In order to vary these parameters over a wide range two experimental works have been devoted to systems of excited alkali atoms colliding with ground state alkali atoms. In the first study Rb atoms are excited to various ns or nd states from Rb(5d) to Rb(9s) in a cell. The second study is devoted to the Na(3p)-Na(3s) system, in this study also the possibility of creating excited negative ions (Na - (3s3p)) has been investigated. These results are presented and analyzed. Finally further developments of the subject are suggested. 17 refs.; 8 figs.; 1 table

  12. Giant resonances on excited states

    International Nuclear Information System (INIS)

    Besold, W.; Reinhard, P.G.; Toepffer, C.

    1984-01-01

    We derive modified RPA equations for small vibrations about excited states. The temperature dependence of collective excitations is examined. The formalism is applied to the ground state and the first excited state of 90 Zr in order to confirm a hypothesis which states that not only the ground state but every excited state of a nucleus has a giant resonance built upon it. (orig.)

  13. Excitation of Nucleon Resonances

    International Nuclear Information System (INIS)

    Burkert, Volker D.

    2001-01-01

    I discuss developments in the area of nucleon resonance excitation, both necessary and feasible, that would put our understanding of nucleon structure in the regime of strong QCD on a qualitatively new level. They involve the collection of high quality data in various channels, a more rigorous approach in the search for ''missing'' resonances, an effort to compute some critical quantities in nucleon resonance excitations from first principles, i.e. QCD, and a proposal focused to obtain an understanding of a fundamental quantity in nucleon structure

  14. Can Measured Synergy Excitations Accurately Construct Unmeasured Muscle Excitations?

    Science.gov (United States)

    Bianco, Nicholas A; Patten, Carolynn; Fregly, Benjamin J

    2018-01-01

    Accurate prediction of muscle and joint contact forces during human movement could improve treatment planning for disorders such as osteoarthritis, stroke, Parkinson's disease, and cerebral palsy. Recent studies suggest that muscle synergies, a low-dimensional representation of a large set of muscle electromyographic (EMG) signals (henceforth called "muscle excitations"), may reduce the redundancy of muscle excitation solutions predicted by optimization methods. This study explores the feasibility of using muscle synergy information extracted from eight muscle EMG signals (henceforth called "included" muscle excitations) to accurately construct muscle excitations from up to 16 additional EMG signals (henceforth called "excluded" muscle excitations). Using treadmill walking data collected at multiple speeds from two subjects (one healthy, one poststroke), we performed muscle synergy analysis on all possible subsets of eight included muscle excitations and evaluated how well the calculated time-varying synergy excitations could construct the remaining excluded muscle excitations (henceforth called "synergy extrapolation"). We found that some, but not all, eight-muscle subsets yielded synergy excitations that achieved >90% extrapolation variance accounted for (VAF). Using the top 10% of subsets, we developed muscle selection heuristics to identify included muscle combinations whose synergy excitations achieved high extrapolation accuracy. For 3, 4, and 5 synergies, these heuristics yielded extrapolation VAF values approximately 5% lower than corresponding reconstruction VAF values for each associated eight-muscle subset. These results suggest that synergy excitations obtained from experimentally measured muscle excitations can accurately construct unmeasured muscle excitations, which could help limit muscle excitations predicted by muscle force optimizations.

  15. Excitation of Stellar Pulsations

    DEFF Research Database (Denmark)

    Houdek, G.

    2012-01-01

    In this review I present an overview of our current understanding of the physical mechanisms that are responsible for the excitation of pulsations in stars with surface convection zones. These are typically cooler stars such as the δ Scuti stars, and stars supporting solar-like oscillations....

  16. Relativistic Coulomb excitation

    International Nuclear Information System (INIS)

    Winther, A.; Alder, K.

    1979-01-01

    Coulomb excitation of both target and projectile in relativistic heavy ion collisions is evaluated including the lowest order correction for the deviation from a straight line trajectory. Explicit results for differential and total cross sections are given in the form of tables and figures. (Auth.)

  17. Excited lepton search

    International Nuclear Information System (INIS)

    Behrend, H.J.; Buerger, J.; Criegee, L.; Fenner, H.; Field, J.H.; Franke, G.; Fuster, J.; Holler, Y.; Meyer, J.; Schroeder, V.; Sindt, H.; Timm, U.; Winter, G.G.; Zimmermann, W.; Bussey, P.J.; Campbell, A.J.; Dainton, J.B.; Hendry, D.; McCurrach, G.; Scarr, J.M.; Skillicorn, I.O.; Smith, K.M.; Blobel, V.; Poppe, M.; Spitzer, H.; Boer, W. de; Buschhorn, G.; Christiansen, W.; Grindhammer, G.; Gunderson, B.; Kiesling, C.; Kotthaus, R.; Kroha, H.; Lueers, D.; Oberlack, H.; Sack, B.; Schacht, P.; Shooshtari, G.; Wiedenmann, W.; Cordier, A.; Davier, M.; Fournier, D.; Gaillard, M.; Grivaz, J.F.; Haissinski, J.; Janot, P.; Journe, V.; Le Diberder, F.; Ros, E.; Spadafora, A.; Veillet, J.J.; Aleksan, R.; Cozzika, G.; Ducros, Y.; Jarry, P.; Lavagne, Y.; Ould Saada, F.; Pamela, J.; Pierre, F.; Zacek, J.; Alexander, G.; Bella, G.; Gnat, Y.; Grunhaus, J.

    1986-02-01

    Using the CELLO detector at PETRA we have searched for excited leptons by studying e + e - interactions which yield p + p - γγ, l + l - γ and γγ final states, where l = 3, μ or τ. We observe good agreement with QED and set new limits on e*, μ*, and τ* production. (orig.)

  18. Hardness and excitation energy

    Indian Academy of Sciences (India)

    It is shown that the first excitation energy can be given by the Kohn-Sham hardness (i.e. the energy difference of the ground-state lowest unoccupied and highest occupied levels) plus an extra term coming from the partial derivative of the ensemble exchange-correlation energy with respect to the weighting factor in the ...

  19. The effects of reactants ratios, reaction temperatures and times on Maillard reaction products of the L-ascorbic acid/L-glutamic acid system

    Directory of Open Access Journals (Sweden)

    Yong-Yan ZHOU

    2016-01-01

    Full Text Available Abstract The transformation law of the Maillard reaction products with three different reactants ratios - equimolar reactants, excess L-glutamic acid and excess L-ascorbic acid reaction respectively, five different temperatures, and different time conditions for the L-ascorbic acid / L-glutamic acid system were investigated. Results showed that, the increase of the reaction time and temperature led to the increase of the browning products, uncoloured intermediate products, as well as aroma compounds. Compared with the equimolar reaction system, the excess L-ascorbic acid reaction system produced more browning products and uncoloured intermediate products, while the aroma compounds production remained the same. In the excess L-glutamic acid system, the uncoloured intermediate products increased slightly, the browning products remained the same, while the aroma compounds increased.

  20. Redox flow batteries with serpentine flow fields: Distributions of electrolyte flow reactant penetration into the porous carbon electrodes and effects on performance

    Science.gov (United States)

    Ke, Xinyou; Prahl, Joseph M.; Alexander, J. Iwan D.; Savinell, Robert F.

    2018-04-01

    Redox flow batteries with flow field designs have been demonstrated to boost their capacities to deliver high current density and power density in medium and large-scale energy storage applications. Nevertheless, the fundamental mechanisms involved with improved current density in flow batteries with serpentine flow field designs have been not fully understood. Here we report a three-dimensional model of a serpentine flow field over a porous carbon electrode to examine the distributions of pressure driven electrolyte flow penetrations into the porous carbon electrodes. We also estimate the maximum current densities associated with stoichiometric availability of electrolyte reactant flow penetrations through the porous carbon electrodes. The results predict reasonably well observed experimental data without using any adjustable parameters. This fundamental work on electrolyte flow distributions of limiting reactant availability will contribute to a better understanding of limits on electrochemical performance in flow batteries with serpentine flow field designs and should be helpful to optimizing flow batteries.

  1. Nonlinear excitations in biomolecules

    International Nuclear Information System (INIS)

    Peyrard, M.

    1995-01-01

    The aim of the workshop entitled ''Nonlinear Excitations in Biomolecules'' is to attempt to bridge the gap between the physicists and biologists communities which is mainly due to language and cultural barriers. The progress of nonlinear science in the last few decades which have shown that the combination of nonlinearity, which characterize most biological phenomena, and cooperative effects in a system having a large number of degrees of freedom, can give rise to coherent excitations with remarkable properties. New concepts, such as solitons nd nonlinear energy localisation have become familiar to physicists and applied mathematicians. It is thus tempting to make an analogy between these coherent excitations and the exceptional stability of some biological processes, such as for instance DNA transcription, which require the coordination of many events in the ever changing environment of a cell. Physicists are now invoking nonlinear excitations to describe and explain many bio-molecular processes while biologists often doubt that the seemingly infinite variety of phenomena that they are attempting to classify can be reduced to such simple concepts. A large part of the meeting is devoted to tutorial lectures rather than to latest research results. The book provides a pedagogical introduction to the two topics forming the backbone of the meeting: the theory of nonlinear excitations and solitons, and their application in biology; and the structure and function of biomolecules, as well as energy and charge transport in biophysics. In order to emphasize the link between physics and biology, the volume is not divided along these two topics but according to biological subjects. Each chapter starts with a short introduction attempting to help the reader to find his way among the contributions and point out the connection between them. 23 lectures over the 32 presented have been selected and refers to quantum properties of macro-molecules. (J.S.)

  2. Nuclear transitions induced by atomic excitations

    International Nuclear Information System (INIS)

    Dyer, P.; Bounds, J.A.; Haight, R.C.; Luk, T.S.

    1988-01-01

    In the two-step pumping scheme for a gamma-ray laser, an essential step is that of exciting the nucleus from a long-lived storage isomer to a nearby short- lived state that then decays to the upper lasing level. An experiment is in progress to induce this transfer by first exciting the atomic electrons with UV photons. The incident photons couple well to the electrons, which then couple via a virtual photon to the nucleus. As a test case, excitation of the 235 U nucleus is being sought, using a high- brightness UV laser. The excited nuclear state, having a 26- minute half-life, decays by internal conversion, resulting in emission of an atomic electron. A pulsed infrared laser produces an atomic beam of 235 U which is then bombarded by the UV laser beam. Ions are collected, and conversion electrons are detected by a channel electron multiplier. In preliminary experiments, an upper limit of 7 x 10 -5 has been obtained for the probability of exciting a 235 U atom in the UV beam for one picosecond at an intensity of about 10 15 W/cm 2 . Experiments with higher sensitivities and at higher UV beam intensities are underway

  3. Excited nuclei fragmentation

    International Nuclear Information System (INIS)

    Ngo, C.

    1986-11-01

    Experimental indications leading to the thought of a very excited nucleus fragmentation are resumed. Theoretical approaches are briefly described; they are used to explain the phenomenon in showing off they are based on a minimum information principle. This model is based on time dependent Thomas-Fermi calculation which allows the mean field effect description, and with a site-bound percolation model which allows the fluctuation description [fr

  4. Harmonically excited orbital variations

    International Nuclear Information System (INIS)

    Morgan, T.

    1985-01-01

    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

  5. Reactive scattering of electronically excited alkali atoms with molecules

    International Nuclear Information System (INIS)

    Mestdagh, J.M.; Balko, B.A.; Covinsky, M.H.; Weiss, P.S.; Vernon, M.F.; Schmidt, H.; Lee, Y.T.

    1987-06-01

    Representative families of excited alkali atom reactions have been studied using a crossed beam apparatus. For those alkali-molecule systems in which reactions are also known for ground state alkali and involve an early electron transfer step, no large differences are observed in the reactivity as Na is excited. More interesting are the reactions with hydrogen halides (HCl): it was found that adding electronic energy into Na changes the reaction mechanism. Early electron transfer is responsible of Na(5S, 4D) reactions, but not of Na(3P) reactions. Moreover, the NaCl product scattering is dominated by the HCl - repulsion in Na(5S, 4D) reactions, and by the NaCl-H repulsion in the case of Na(3P). The reaction of Na with O 2 is of particular interest since it was found to be state specific. Only Na(4D) reacts, and the reaction requires restrictive constraints on the impact parameter and the reactants' relative orientation. The reaction with NO 2 is even more complex since Na(4D) leads to the formation of NaO by two different pathways. It must be mentioned however, that the identification of NaO as product in these reactions has yet to be confirmed

  6. A scalable piezoelectric impulse-excited energy harvester for human body excitation

    International Nuclear Information System (INIS)

    Pillatsch, P; Yeatman, E M; Holmes, A S

    2012-01-01

    Harvesting energy from low-frequency and non-harmonic excitations typical of human motion presents specific challenges. While resonant devices do have an advantage in environments where the excitation frequency is constant, and while they can make use of the entire proof mass travel range in the case of excitation amplitudes that are smaller than the internal displacement limit, they are not suitable for body applications since the frequencies are random and the amplitudes tend to be larger than the device size. In this paper a piezoelectric, impulse-excited approach is presented. A cylindrical proof mass actuates an array of piezoelectric bi-morph beams through magnetic attraction. After the initial excitation these transducers are left to vibrate at their natural frequency. This increases the operational frequency range as well as the electromechanical coupling. The principle of impulse excitation is discussed and a centimetre-scale functional model is introduced as a proof of concept. The obtained data show the influence of varying the frequency, acceleration and proof mass. Finally, a commercially available integrated circuit for voltage regulation is tested. At a frequency of 2 Hz and an acceleration of 2.7 m s −2 a maximal power output of 2.1 mW was achieved. (paper)

  7. Excited QCD 2017

    CERN Document Server

    2017-01-01

    This edition is the ninth in a series of workshops that had been previously organised in Poland (2009), Slovakia (2010 and 2015), France (2011), Portugal (2012 and 2016) and Bosnia and Herzegovina (2013 and 2014). In the year 2017 the workshop goes to the beautiful Sintra near Lisbon, Portugal. The workshop covers diverse aspects of QCD: (i) QCD at low energies: excited hadrons, new resonances, glueballs, multiquarks. (ii) QCD at high temperatures and large densities: heavy-ion collisions, jets, diffraction, hadronisation, quark-gluon plasma, holography, colour-glass condensate, compact stars, applications to astrophysics.

  8. Highly excited atoms

    International Nuclear Information System (INIS)

    Kleppner, D.; Littman, M.G.; Zimmerman, M.L.

    1981-01-01

    Highly excited atoms are often called Rydberg atoms. These atoms have a wealth of exotic properties which are discussed. Of special interest, are the effects of electric and magnetic fields on Rydberg atoms. Ordinary atoms are scarcely affected by an applied electric or magnetic field; Rydberg atoms can be strongly distorted and even pulled apart by a relatively weak electric field, and they can be squeezed into unexpected shapes by a magnetic field. Studies of the structure of Rydberg atoms in electric and magnetic fields have revealed dramatic atomic phenomena that had not been observed before

  9. Realisation and crossed molecular beams study of H2/O chemical reactions at several excited states

    International Nuclear Information System (INIS)

    Marx, Jacqueline

    1986-01-01

    This work is devoted to the study of the reactive collision O + H 2 OH + H in a crossed beam experiment. This process including several channels taken a part in the chemistry of the upper atmosphere as well as in the combustion of hydrogen. According to the electronic or vibrational state of the reactants, the OH radical is produced in its ground electronic state OH (X 2 π) or in its first excited state OH (A 2 Σ + ). When the reactants are in their ground state, the reaction is endothermic in the conditions of the experiment (center of mass kinetic energy ≅ 0.12 eV). The following reactions have been obtained: O( 1 D) +H 2 (v=O) → OH (X 2 π) +H( 2 S) and O( 1 D) +H 2 (v≥5) → OH (A 2 Σ + ) +H( 2 S). The atomic oxygen is produced in its excited state O( 1 D) in a radio-frequency discharge which dissociates the molecular oxygen seeded in a carrier gas (He or Ar) and the hydrogen molecules are excited vibrationally by electron bombardment. The first reaction is studied by time-of-flight measurements. In this way, it has been possible to observe the different vibrational levels on which the OH radical is produced. The analysis of this vibrational distribution shows the competition between the abstraction and insertion-dissociation mechanisms. In the second reaction, the analysis of the spontaneous fluorescence of OH (A 2 Σ + ) reveals a very hot and non-Boltzmann rotational excitation. (author) [fr

  10. Effect of reactant concentration on the structural properties of hydrothermally-grown ZnO rods on seed-layer ZnO / polyethylene terephthalate substrates

    Energy Technology Data Exchange (ETDEWEB)

    Jeong, Y. I.; Shin, C. M.; Heo, J. H.; Ryu, H. [Inje University, Gimhae (Korea, Republic of); Lee, W. J. [Dong-Eui University, Busan (Korea, Republic of); Son, C. S. [Silla University, Busan (Korea, Republic of); Choi, H. [Pukyong National University, Busan (Korea, Republic of)

    2011-09-15

    The morphology and the structural properties were studied for zinc-oxide (ZnO) rods hydrothermally grown on seed-layer ZnO/polyethylene terephthalate (PET) substrates at various reactant concentrations. Dissolved solutions with de-ionized water, zinc nitrate hexahydrate (Zn(NO{sub 3}){sub 2}{center_dot}6H{sub 2}O, ZNH) and hexamethylenetetramine (C{sub 6}H{sub 12}N{sub 4}, HMT) were employed as reactants for hydrothermal growth of ZnO. The transparency of the mixtures (ZNH+HMT) with increasing reactant concentration from 0.025 to 0.25 M changed from transparent to translucent to opaque (white colors) due to Zn(OH){sub 2} precipitates. When the concentration was increased, the density of the ZnO rods increased, and the morphology of the ZnO rods changed from a hexagonal flat-end shape to a sharp-end or flake-like structure. The sharp-end rods with increasing concentration from 0.1 to 0.15 M resulted from the etching process at a lower pH condition (less than pH 6) after the ZnO rod growth, and the flake-like structure was due to a high growth rate. The ZnO seed layer might have improved the alignment of ZnO rods and made a high density of ZnO rods. In addition, the structural properties were improved at lower concentrations by inserting a seed layer.

  11. CINE: Comet INfrared Excitation

    Science.gov (United States)

    de Val-Borro, Miguel; Cordiner, Martin A.; Milam, Stefanie N.; Charnley, Steven B.

    2017-08-01

    CINE calculates infrared pumping efficiencies that can be applied to the most common molecules found in cometary comae such as water, hydrogen cyanide or methanol. One of the main mechanisms for molecular excitation in comets is the fluorescence by the solar radiation followed by radiative decay to the ground vibrational state. This command-line tool calculates the effective pumping rates for rotational levels in the ground vibrational state scaled by the heliocentric distance of the comet. Fluorescence coefficients are useful for modeling rotational emission lines observed in cometary spectra at sub-millimeter wavelengths. Combined with computational methods to solve the radiative transfer equations based, e.g., on the Monte Carlo algorithm, this model can retrieve production rates and rotational temperatures from the observed emission spectrum.

  12. Soliton excitation in superlattice

    International Nuclear Information System (INIS)

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

    1995-10-01

    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 0 and that an increase in the amplitude causes soliton width L to approach zero and the velocity u to that of light V in homogeneous medium. The characteristic parameters of soliton u, L and E 0 are related by expression u/L E 0 = ed/2(h/2π) which is constant depending only on the SL period d. It is observed also that the soliton has both energy E = 8V 2 (1 - u 2 /V 2 ) -1/2 and momentum P = u/V 2 E which makes it behave as relativistic free particle with rest energy 8V 2 . Its interaction with electrons can cause the soliton electric effect in SL. (author). 27 refs

  13. Replacing Chlorine with Hydrogen Chloride as a Possible Reactant for Synthesis of Titanium Carbide Derived Carbon Powders for High-Technology Devices

    International Nuclear Information System (INIS)

    Tallo, Indrek; Thomberg, Thomas; Jänes, Alar; Lust, Enn

    2013-01-01

    Micro- and mesoporous carbide-derived carbons were synthesized from titanium carbide (TiC) powder via gas phase reaction by using different reactants (Cl 2 and HCl) within the temperature range from 700 to 1100 °C. Analysis of XRD results show that TiC-derived carbons (TiC-CDC) consist mainly of graphitic crystallites. The first-order Raman spectra showed the graphite-like absorption peaks at ∼1577 cm 1 and the disorder-induced peaks at ∼1338 cm- 1 . The energy-related properties of supercapacitors based on 1 M (C 2 H 5 ) 3 CH 3 NBF 4 in acetonitrile and carbide-derived carbons (TiC-CDC (Cl 2 ) and TiC-CDC (HCl)) as electrode materials were also investigated using cyclic voltammetry, electrochemical impedance spectroscopy, galvanostatic charge/discharge and constant power methods. The Ragone plots for carbide-derived carbons prepared by using different reactants (Cl 2 , HCl) are quite similar and at high power loads TiC-CDC (Cl 2 ) material synthesized at 900 °C, i.e. materials with optimal porous structure, deliver higher power at constant energy

  14. The impact of reactants composition and temperature on the flow structure in a wake stabilized laminar lean premixed CH4/H2/air flames; mechanism and scaling

    KAUST Repository

    Michaels, D.

    2016-11-11

    In this paper we investigate the role of reactants composition and temperature in defining the steady flow structure in bluff body stabilized premixed flames. The study was motivated by experiments which showed that the flow structure and stability map for different fuels and inlet conditions collapse using the extinction strain rate as the chemical time scale. The investigation is conducted using a laminar lean premixed flame stabilized on a heat conducting bluff-body. Calculations are performed for a wide range of mixtures of CH4/H2/air (0.35 ≤ ϕ ≤ 0.75, 0 ≤ %H2 ≤ 40, 300 ≤ Tin [K] ≤ 500) in order to systematically vary the burning velocity (2.0–35.6 cm/s), dilatation ratio (2.7–6.4), and extinction strain rate (106–2924 1/s). The model is based on a fully resolved unsteady two-dimensional flow with detailed chemistry and species transport, and with no artificial flame anchoring boundary conditions. Calculations reveal that the recirculation zone length correlates with a chemical time scale based on the flame extinction strain rate corresponding to the inlet fuel composition, stoichiometry, pressure and temperature; and are consistent with experimental data in literature. It was found that in the wake region the flame is highly stretched and its location and interaction with the flow is governed by the reactants combustion characteristics under high strain.

  15. A three-dimensional numerical investigation of trapezoid baffles effect on non-isothermal reactant transport and cell net power in a PEMFC

    International Nuclear Information System (INIS)

    Perng, Shiang-Wuu; Wu, Horng-Wen

    2015-01-01

    Highlights: • We study how angle and height of trapezoid baffle affect PEMFC net power. • The jet-type, trapping, and blockage effects augment non-isothermal transport in flow channel. • Greater angles and heights of trapezoid baffles provide more reactant to the catalyst layer. • Baffles of 1.5 mm and 90° fully block flow channel to show bad heat transfer and large pressure drop. • Maximum enhancement of cell net power is 90% with baffles of 60° angle and 1.125 mm height. - Abstract: The present study performed a three-dimensional numerical simulation to observe how trapezoid baffles affect non-isothermal reactant transports and cell net power in the proton exchange membrane fuel cell (PEMFC) by the SIMPLE-C method. The geometric parameters of trapezoid baffles installed in the gas channel employed in this study include the angle and height with the same gas diffusion and catalyst layers to realize the cell net power considering the effect of liquid water formation on the fluid flow field. The cell net power is adopted to evaluate the real enhancement of cell performance due to the additional pumping power induced by the pressure loss through the PEMFC. The results illustrated that compared with traditional gas channel without baffles, the novel gas channel with trapezoid baffles, whose angle is 60° and height is 1.125 mm, enhances the cell net power best by approximately 90% among all trapezoid baffle designs

  16. A Chebyshev method for state-to-state reactive scattering using reactant-product decoupling: OH + H2 → H2O + H.

    Science.gov (United States)

    Cvitaš, Marko T; Althorpe, Stuart C

    2013-08-14

    We extend a recently developed wave packet method for computing the state-to-state quantum dynamics of AB + CD → ABC + D reactions [M. T. Cvitaš and S. C. Althorpe, J. Phys. Chem. A 113, 4557 (2009)] to include the Chebyshev propagator. The method uses the further partitioned approach to reactant-product decoupling, which uses artificial decoupling potentials to partition the coordinate space of the reaction into separate reactant, product, and transition-state regions. Separate coordinates and basis sets can then be used that are best adapted to each region. We derive improved Chebyshev partitioning formulas which include Mandelshtam-and-Taylor-type decoupling potentials, and which are essential for the non-unitary discrete variable representations that must be used in 4-atom reactive scattering calculations. Numerical tests on the fully dimensional OH + H2 → H2O + H reaction for J = 0 show that the new version of the method is as efficient as the previously developed split-operator version. The advantages of the Chebyshev propagator (most notably the ease of parallelization for J > 0) can now be fully exploited in state-to-state reactive scattering calculations on 4-atom reactions.

  17. Charmonium non-potential excitations

    International Nuclear Information System (INIS)

    Borue, V.Y.; Khokhlachev, S.B.

    1990-01-01

    Within the framework of an effective theory of quantum gluodynamics formulated earlier in terms of the glueball degrees of freedom, the excitations of gluon bunch formed by heavy quark and antiquark are considered. It is shown that these excitations correspond to the vibration of the gluon bunch shape and lie nearly 800 MeV higher than the charmonium ground state. The consequences of the existence of these excitations are discussed

  18. Fission fragment excited laser system

    Science.gov (United States)

    McArthur, David A.; Tollefsrud, Philip B.

    1976-01-01

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

  19. The excited states of 79Kr

    International Nuclear Information System (INIS)

    Liptak, J.; Kristiak, J.; Kristiakova, K.

    1977-01-01

    The β + -decay of 79 Rb has been studied with Ge(Li) detectors in single and coincidence modes. The half-life of the 147.06 keV level in 79 Kr has been determined to be (78+-6) ns. The relative electron intensities of seventeen transitions have been measured with a magnetic Si(Li) spectrometer. The internal conversion coefficients have been determined. The transition multipolarities have been deduced. The spin-parity assignments have been made for excited states of 79 Kr and a β-decaying sta 79 Rb(5/2 + ). The structure of excited states in 79 Kr is discussed in the framework of the Alaga and Coriolis coupling models. It is shown that the properties of some levels in 79 Kr can be explained by the existence of relatively pure rotational bands

  20. Excited-state relaxation of some aminoquinolines

    Directory of Open Access Journals (Sweden)

    2006-01-01

    Full Text Available The absorption and fluorescence spectra, fluorescence quantum yields and lifetimes, and fluorescence rate constants ( k f of 2-amino-3-( 2 ′ -benzoxazolylquinoline (I, 2-amino-3-( 2 ′ -benzothiazolylquinoline (II, 2-amino-3-( 2 ′ -methoxybenzothiazolyl-quinoline (III, 2-amino-3-( 2 ′ -benzothiazolylbenzoquinoline (IV at different temperatures have been measured. The shortwavelength shift of fluorescence spectra of compounds studied (23–49 nm in ethanol as the temperature decreases (the solvent viscosity increases points out that the excited-state relaxation process takes place. The rate of this process depends essentially on the solvent viscosity, but not the solvent polarity. The essential increasing of fluorescence rate constant k f (up to about 7 times as the solvent viscosity increases proves the existence of excited-state structural relaxation consisting in the mutual internal rotation of molecular fragments of aminoquinolines studied, followed by the solvent orientational relaxation.

  1. Vibrational-rotational excitation: chemical reactions of vibrationally excited molecules

    International Nuclear Information System (INIS)

    Moore, C.B.; Smith, I.W.M.

    1979-03-01

    This review considers a limited number of systems, particularly gas-phase processes. Excited states and their preparation, direct bimolecular reactions, reactions of highly excited molecules, and reactions in condensed phases are discussed. Laser-induced isotope separation applications are mentioned briefly. 109 references

  2. Excitation of nuclear states by synchrotron radiation

    International Nuclear Information System (INIS)

    Olariu, Albert

    2003-01-01

    We study the excitation of nuclear states by gamma ray beams of energy up to 200 keV produced as synchrotron radiation. We consider the possibility to populate an excited state |i> in two steps, from the ground state |g> to an intermediary state |n> which decays by gamma emission or internal conversion to a lower state |i>. The aim of this study is to establish that the probability P 2 of the two-step transition |g> → |n> → |i> should be greater than the probability P 1 of the direct transition |g> → |i>. The probabilities P 1 and P 2 correspond to a radiation pulse of duration equal to the half-time of the state |i>. We have written a computer program in C++ which computes the probability P 2 , the ratio P 2 /P 1 and the rate C 2 of the two-step transitions for any nuclei and different configurations of states. The program uses a database which contains information on the energy levels, half-lives, spins and parities of nuclear states and on the relative intensities of the nuclear transitions. If the half-lives or the relative intensities are not known the program uses the Weisskopf estimates for the transition half-lives. An interpolation program of internal conversion coefficients has also been used. We listed the values obtained for P 2 , P 2 /P 1 and C 2 in a number of cases in which P 2 is significant from the 2900 considered cases. The states |i> and |n> have the energies E i and E n , the corresponding half-lives being t i and t n . The spectral density of the synchrotron radiation has been considered to be 10 12 photons cm -2 s -1 eV -1 . We listed only the cases for which the relative intensities of the transitions from levels |n> and |i> to lower states are known. The calculations carried out in this study allowed us to identify nuclei for which P 2 has relatively great values. In the listed cases P 2 /P 1 >>1, so that the two-step excitation by synchrotron radiation is more efficient than the direct excitation |g> → |i>. For a sample having 10

  3. High energy magnetic excitations

    International Nuclear Information System (INIS)

    Endoh, Yasuo

    1988-01-01

    The report emphasizes that the current development in condensed matter physics opens a research field fit to inelastic neutron scattering experiments in the eV range which is easilly accessed by spallation neutron sources. Several important subjects adopted at thermal reactors are shown. It is desired to extend the implementation of the spectroscopic experiments for investigation of higher energy magnetic excitations. For La 2 CuO 4 , which is the mother crystal of the first high Tc materials found by Bednortz and Muller, it seems to be believed that the magnetism is well characterized by the two-dimensional Heisenberg antiferromagnetic Hamiltonian, and it is widely accepted that the magnetism is a most probable progenitor of high Tc superconductors. The unusual properties of spin correlations in this crystal have been studied extensively by standard neutron scattering techniques with steady neutrons at BNL. FeSi is not ordered magnetically but shows a very unique feature of temperature induced magnetism, which also has been studied extensively by using the thermal neutron scattering technique at BNL. In these experiments, polarized neutrons are indispensable to extract the clean magnetic components out of other components of non-magnetic scattering. (N.K.)

  4. Topological excitations in magnetic materials

    Energy Technology Data Exchange (ETDEWEB)

    Bazeia, D., E-mail: bazeia@fisica.ufpb.br [Departamento de Física, Universidade Federal da Paraíba, 58051-970 João Pessoa, PB (Brazil); Doria, M.M. [Instituto de Física, Universidade Federal do Rio de Janeiro, Rio de Janeiro (Brazil); Dipartimento di Fisica, Università di Camerino, I-62032 Camerino (Italy); Rodrigues, E.I.B. [Departamento de Física, Universidade Federal da Paraíba, 58051-970 João Pessoa, PB (Brazil)

    2016-05-20

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

  5. Excited waves in shear layers

    Science.gov (United States)

    Bechert, D. W.

    1982-01-01

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

  6. Antiphase dual-color correlation in a reactant-product pair imparts ultrasensitivity in reaction-linked double-photoswitching fluorescence imaging.

    Science.gov (United States)

    Wan, Wei; Zhu, Ming-Qiang; Tian, Zhiyuan; Li, Alexander D Q

    2015-04-08

    A pair of reversible photochemical reactions correlates their reactant and product specifically, and such a correlation uniquely distinguishes their correlated signal from others that are not linked by this reversible reaction. Here a nanoparticle-shielded fluorophore is photodriven to undergo structural dynamics, alternating between a green-fluorescence state and a red-fluorescence state. As time elapses, the fluorophore can be in either state but not both at the same time. Thus, the red fluorescence is maximized while the green fluorescence is minimized and vice versa. Such an antiphase dual-color (AD) corelationship between the red and green fluorescence maxima as well as between their minima can be exploited to greatly improve the signal-to-noise ratio, thus enhancing the ultimate detection limit. Potential benefits of this correlation include elimination of all interferences originating from single-color dyes and signal amplification of AD photoswitching molecules by orders of magnitude.

  7. Chiral Selectivity in Inter-reactant Recognition and Electron Transfer of the Oxidation of Horse Heart Cytochrome c by Trioxalatocobaltate(III)

    DEFF Research Database (Denmark)

    Nazmutdinov, Renat R.; Bronshtein, Michael D.; Zinkicheva, Tamara T.

    2016-01-01

    We have studied electron transfer between cytochrome c and the chiral transition-metal complex pair Λ- and Δ-[Co(Ox)3]3− (Ox2− = oxalate) via strong ion-pair formation. Chirality was found in both ion-pair formation and electron transfer, with the Λ enantiomer the more strongly bound and faster r...... reacting. Investigations of the chirality using electron-transfer theory combined with quantum-chemical and statistical-mechanical calculations showed that chirality is solely in inter-reactant interaction and electronic overlap.......We have studied electron transfer between cytochrome c and the chiral transition-metal complex pair Λ- and Δ-[Co(Ox)3]3− (Ox2− = oxalate) via strong ion-pair formation. Chirality was found in both ion-pair formation and electron transfer, with the Λ enantiomer the more strongly bound and faster...

  8. Agent-based simulation of reactions in the crowded and structured intracellular environment: Influence of mobility and location of the reactants

    Directory of Open Access Journals (Sweden)

    Lapin Alexei

    2011-05-01

    Full Text Available Abstract Background In this paper we apply a novel agent-based simulation method in order to model intracellular reactions in detail. The simulations are performed within a virtual cytoskeleton enriched with further crowding elements, which allows the analysis of molecular crowding effects on intracellular diffusion and reaction rates. The cytoskeleton network leads to a reduction in the mobility of molecules. Molecules can also unspecifically bind to membranes or the cytoskeleton affecting (i the fraction of unbound molecules in the cytosol and (ii furthermore reducing the mobility. Binding of molecules to intracellular structures or scaffolds can in turn lead to a microcompartmentalization of the cell. Especially the formation of enzyme complexes promoting metabolic channeling, e.g. in glycolysis, depends on the co-localization of the proteins. Results While the co-localization of enzymes leads to faster reaction rates, the reduced mobility decreases the collision rate of reactants, hence reducing the reaction rate, as expected. This effect is most prominent in diffusion limited reactions. Furthermore, anomalous diffusion can occur due to molecular crowding in the cell. In the context of diffusion controlled reactions, anomalous diffusion leads to fractal reaction kinetics. The simulation framework is used to quantify and separate the effects originating from molecular crowding or the reduced mobility of the reactants. We were able to define three factors which describe the effective reaction rate, namely f diff for the diffusion effect, f volume for the crowding, and f access for the reduced accessibility of the molecules. Conclusions Molecule distributions, reaction rate constants and structural parameters can be adjusted separately in the simulation allowing a comprehensive study of individual effects in the context of a realistic cell environment. As such, the present simulation can help to bridge the gap between in vivo and in vitro

  9. Effects of annealing on the properties of atomic layer deposited Ru thin films deposited by NH{sub 3} and H{sub 2} as reactants

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Seung-Joon; Kim, Soo-Hyun, E-mail: soohyun@ynu.ac.kr

    2016-08-01

    Atomic layer deposition (ALD) of Ru using a non-oxidizing reactant is indispensable considering its application as a seed layer for Cu electroplating and a bottom electrode for dynamic random access memory capacitors. In this study, ALD-Ru films were deposited using a sequential supply of dicarbonyl-bis(5-methyl-2,4-hexanediketonato) Ru(II) (C{sub 16}H{sub 22}O{sub 6}Ru) and potential non-oxidizing reducing agents, NH{sub 3} or H{sub 2}, as the reactants at a substrate temperature of 250 °C, and the effects of post-annealing in a H{sub 2} ambient on the film properties were investigated. The highly conformal deposition of Ru films was possible using the present reaction scheme but its resistivity was as high as ~ 750 μΩ-cm due to carbon incorporation into the film and the formation of an amorphous structure. Low temperature annealing at 300 °C at H{sub 2} ambient after deposition was found to improve the properties significantly in terms of the resistivity, impurities contents and crystallinity. For example, the film resistivity was decreased drastically to ~ 40 μΩ-cm with both the release of C in the film and crystallization after annealing based on secondary ion mass spectrometry and transmission electron microscopy, whereas perfect step coverage at a very small-sized dual trench (aspect ratio: ~ 3, the top opening size of 45 nm and bottom size of 20 nm) was maintained after annealing. - Highlights: • Ru thin films were deposited by atomic layer deposition (ALD) using NH{sub 3} and H{sub 2} molecules. • Effects of low temperature (300 °C) post-annealing on the film properties were investigated. • Post annealing improved the properties of ALD-Ru films. • Perfect step coverage of ALD-Ru was confirmed at trench structure (top opening width: 45 nm).

  10. Excited cooper pairs

    Energy Technology Data Exchange (ETDEWEB)

    Lopez-Arrietea, M. G.; Solis, M. A.; De Llano, M. [Universidad Nacional Autonoma de Mexico, Mexico, D.F (Mexico)

    2001-02-01

    Excited cooper pairs formed in a many-fermion system are those with nonzero total center-of mass momentum (CMM). They are normally neglected in the standard Bardeen-Cooper-Schrieffer (BCS) theory of superconductivity for being too few compared with zero CMM pairs. However, a Bose-Einstein condensation picture requires both zero and nonzero CMM pairs. Assuming a BCS model interaction between fermions we determine the populations for all CMM values of Cooper pairs by actually calculating the number of nonzero-CMM pairs relative to that of zero-CMM ones in both 2D and 3D. Although this ratio decreases rapidly with CMM, the number of Cooper pairs for any specific CMM less than the maximum (or breakup of the pair) momentum turns out to be typically larger than about 95% of those with zero-CMM at zero temperature T. Even at T {approx}100 K this fraction en 2D is still as large as about 70% for typical quasi-2D cuprate superconductor parameters. [Spanish] Los pares de cooper excitados formados en un sistema de muchos electrones, son aquellos con momentos de centro de masa (CMM) diferente de cero. Normalmente estos no son tomados en cuenta en la teoria estandar de la superconductividad de Bardeen-Cooper-Schrieffer (BCS) al suponer que su numero es muy pequeno comparados con los pares de centro de masa igual a cero. Sin embargo, un esquema de condensacion Bose-Einstein requiere de ambos pares, con CMM cero y diferente de cero. Asumiendo una interaccion modelo BCS entre los fermiones, determinamos la poblacion de pares cooper con cada uno de todos los posibles valores del CMM calculando el numero de pares con momentos de centro de masa diferente de cero relativo a los pares de CMM igual a cero, en 2D y 3D. Aunque esta razon decrece rapidamente con el CMM, el numero de pares de cooper para cualquier CMM especifico menor que el momento maximo (o rompimiento de par) es tipicamente mas grande que el 95% de aquellos con CMM cero. Aun a T {approx}100 K esta fraccion en 2D es

  11. Uniform excitations in magnetic nanoparticles

    DEFF Research Database (Denmark)

    Mørup, Steen; Frandsen, Cathrine; Hansen, Mikkel Fougt

    2010-01-01

    We present a short review of the magnetic excitations in nanoparticles below the superparamagnetic blocking temperature. In this temperature regime, the magnetic dynamics in nanoparticles is dominated by uniform excitations, and this leads to a linear temperature dependence of the magnetization...... and the magnetic hyperfine field, in contrast to the Bloch T3/2 law in bulk materials. The temperature dependence of the average magnetization is conveniently studied by Mössbauer spectroscopy. The energy of the uniform excitations of magnetic nanoparticles can be studied by inelastic neutron scattering....

  12. Uniform excitations in magnetic nanoparticles

    Directory of Open Access Journals (Sweden)

    Steen Mørup

    2010-11-01

    Full Text Available We present a short review of the magnetic excitations in nanoparticles below the superparamagnetic blocking temperature. In this temperature regime, the magnetic dynamics in nanoparticles is dominated by uniform excitations, and this leads to a linear temperature dependence of the magnetization and the magnetic hyperfine field, in contrast to the Bloch T3/2 law in bulk materials. The temperature dependence of the average magnetization is conveniently studied by Mössbauer spectroscopy. The energy of the uniform excitations of magnetic nanoparticles can be studied by inelastic neutron scattering.

  13. Excited states in biological systems

    International Nuclear Information System (INIS)

    Cilento, G.; Zinner, K.; Bechara, E.J.H.; Duran, N.; Baptista, R.C. de; Shimizu, Y.; Augusto, O.; Faljoni-Alario, A.; Vidigal, C.C.C.; Oliveira, O.M.M.F.; Haun, M.

    1979-01-01

    Some aspects of bioluminescence related to bioenergetics are discussed: 1. chemical generation of excited species, by means of two general processes: electron transference and cyclic - and linear peroxide cleavage; 2. biological systems capable of generating excited states and 3. biological functions of these states, specially the non-emissive ones (tripletes). The production and the role of non-emissive excited states in biological systems are analysed, the main purpose of the study being the search for non-emissive states. Experiences carried out in biological systems are described; results and conclusions are given. (M.A.) [pt

  14. Exciter For X-Band Transmitter And Receiver

    Science.gov (United States)

    Johns, Carl E.

    1989-01-01

    Report describes developmental X-band exciter for X-band uplink subsystem of Deep Space Network. X-band transmitter-exciting signal expected to have fractional frequency stability of 5.2 X 10 to negative 15th power during 1,000-second integration period. Generates coherent test signals for S- and X-band Block III translator of Deep Space Network, Doppler-reference signal for associated Doppler-extractor system, first-local-oscillator signal for associated receiver, and reference signal for associated ranging subsystem. Tests of prototype exciter show controlling and monitoring and internal phase-correcting loops perform according to applicable design criteria. Measurements of stability of frequency and of single-sideband noise spectral density of transmitter-exciting signal made subsequently.

  15. Scattering of highly excited atoms

    International Nuclear Information System (INIS)

    Raith, W.

    1980-01-01

    Experimental methods to excite atomic beams into Rydberg states and the first results of collision experiments with such beams are reported. For further information see hints under relevant topics. (orig.) [de

  16. High power laser exciter accelerators

    International Nuclear Information System (INIS)

    Martin, T.H.

    1975-01-01

    Recent developments in untriggered oil and water switching now permit the construction of compact, high energy density pulsed power sources for laser excitation. These accelerators, developed principally for electron beam fusion studies, appear adaptable to laser excitation and will provide electron beams of 10 13 to 10 14 W in the next several years. The accelerators proposed for e-beam fusion essentially concentrate the available power from the outside edge of a disk into the central region where the electron beam is formed. One of the main problem areas, that of power flow at the vacuum diode insulator, is greatly alleviated by the multiplicity of electron beams that are allowable for laser excitation. A proposal is made whereby the disk-shaped pulsed power sections are stacked vertically to form a series of radially flowing electron beams to excite the laser gas volume. (auth)

  17. Autowaves in moving excitable media

    Directory of Open Access Journals (Sweden)

    V.A.Davydov

    2004-01-01

    Full Text Available Within the framework of kinematic theory of autowaves we suggest a method for analytic description of stationary autowave structures appearing at the boundary between the moving and fixed excitable media. The front breakdown phenomenon is predicted for such structures. Autowave refraction and, particulary, one-side "total reflection" at the boundary is considered. The obtained analytical results are confirmed by computer simulations. Prospects of the proposed method for further studies of autowave dynamics in the moving excitable media are discussed.

  18. Magnetic excitations in amorphous ferromagnets

    International Nuclear Information System (INIS)

    Continentino, M.A.

    The propagation of magnetic excitations in amorphous ferromagnets is studied from the point of view of the theory of random frequency modulation. It is shown that the spin waves in the hydrodynamic limit are well described by perturbation theory while the roton-like magnetic excitations with wavevector about the peak in the structure factor are not. A criterion of validity of perturbation theory is found which is identical to a narrowing condition in magnetic resonance. (author) [pt

  19. Excitations of strange bottom baryons

    Energy Technology Data Exchange (ETDEWEB)

    Woloshyn, R.M. [TRIUMF, Vancouver, British Columbia (Canada)

    2016-09-15

    The ground-state and first-excited-state masses of Ω{sub b} and Ω{sub bb} baryons are calculated in lattice QCD using dynamical 2 + 1 flavour gauge fields. A set of baryon operators employing different combinations of smeared quark fields was used in the framework of the variational method. Results for radial excitation energies were confirmed by carrying out a supplementary multiexponential fitting analysis. Comparison is made with quark model calculations. (orig.)

  20. 46 CFR 111.12-3 - Excitation.

    Science.gov (United States)

    2010-10-01

    ... 46 CFR 110.10-1). In particular, no static exciter may be used for excitation of an emergency generator unless it is provided with a permanent magnet or a residual-magnetism-type exciter that has the...

  1. Observation of the adsorption and desorption of vibrationally excited molecules on a metal surface

    Science.gov (United States)

    Shirhatti, Pranav R.; Rahinov, Igor; Golibrzuch, Kai; Werdecker, Jörn; Geweke, Jan; Altschäffel, Jan; Kumar, Sumit; Auerbach, Daniel J.; Bartels, Christof; Wodtke, Alec M.

    2018-06-01

    The most common mechanism of catalytic surface chemistry is that of Langmuir and Hinshelwood (LH). In the LH mechanism, reactants adsorb, become thermalized with the surface, and subsequently react. The measured vibrational (relaxation) lifetimes of molecules adsorbed at metal surfaces are in the range of a few picoseconds. As a consequence, vibrational promotion of LH chemistry is rarely observed, with the exception of LH reactions occurring via a molecular physisorbed intermediate. Here, we directly detect adsorption and subsequent desorption of vibrationally excited CO molecules from a Au(111) surface. Our results show that CO (v = 1) survives on a Au(111) surface for 1 × 10-10 s. Such long vibrational lifetimes for adsorbates on metal surfaces are unexpected and pose an interesting challenge to the current understanding of vibrational energy dissipation on metal surfaces. They also suggest that vibrational promotion of surface chemistry might be more common than is generally believed.

  2. Excited states rotational effects on the behavior of excited molecules

    CERN Document Server

    Lim, Edward C

    2013-01-01

    Excited States, Volume 7 is a collection of papers that discusses the excited states of molecules. The first paper reviews the rotational involvement in intra-molecular in vibrational redistribution. This paper analyzes the vibrational Hamiltonian as to its efficacy in detecting the manifestations of intra-molecular state-mixing in time-resolved and time-averaged spectroscopic measurements. The next paper examines the temporal behavior of intra-molecular vibration-rotation energy transfer (IVRET) and the effects of IVRET on collision, reaction, and the decomposition processes. This paper also

  3. Synaptic control of motoneuronal excitability

    DEFF Research Database (Denmark)

    Rekling, J C; Funk, G D; Bayliss, D A

    2000-01-01

    important in understanding the transformation of neural activity to motor behavior. Here, we review recent studies on the control of motoneuronal excitability, focusing on synaptic and cellular properties. We first present a background description of motoneurons: their development, anatomical organization......, and membrane properties, both passive and active. We then describe the general anatomical organization of synaptic input to motoneurons, followed by a description of the major transmitter systems that affect motoneuronal excitability, including ligands, receptor distribution, pre- and postsynaptic actions...... and norepinephrine, and neuropeptides, as well as the glutamate and GABA acting at metabotropic receptors, modulate motoneuronal excitability through pre- and postsynaptic actions. Acting principally via second messenger systems, their actions converge on common effectors, e.g., leak K(+) current, cationic inward...

  4. Noise induced multidecadal variability in the North Atlantic: excitation of normal modes

    NARCIS (Netherlands)

    Frankcombe, L.M.; Dijkstra, H.A.; von der Heydt, A.S.

    2009-01-01

    In this paper it is proposed that the stochastic excitation of a multidecadal internal ocean mode is at the origin of the multidecadal sea surface temperature variability in the North Atlantic. The excitation processes of the spatial sea surface temperature pattern associated with this multidecadal

  5. Reactants encapsulation and Maillard Reaction

    NARCIS (Netherlands)

    Troise, A.D.; Fogliano, V.

    2013-01-01

    In the last decades many efforts have been addressed to the control of Maillard Reaction products in different foods with the aim to promote the formation of compounds having the desired color and flavor and to reduce the concentration of several potential toxic molecules. Encapsulation, already

  6. Study of temperature, air dew point temperature and reactant flow effects on proton exchange membrane fuel cell performances using electrochemical spectroscopy and voltammetry techniques

    Energy Technology Data Exchange (ETDEWEB)

    Wasterlain, S.; Hissel, D. [FC LAB, Techn' Hom, rue Thierry Mieg, 90010 Belfort Cedex (France); FEMTO-ST (UMR CNRS 6174), ENISYS Department, University of Franche-Comte, Techn' Hom, rue Thierry Mieg, 90010 Belfort Cedex (France); Candusso, D.; Harel, F. [FC LAB, Techn' Hom, rue Thierry Mieg, 90010 Belfort Cedex (France); INRETS, The French National Institute for Transport and Safety Research, Techn' Hom, rue Thierry Mieg, 90010 Belfort Cedex (France); Bergman, P.; Menard, P.; Anwar, M. [University of Connecticut, Connecticut Global Fuel Cell Center Department of Electrical and Computer Engineering, 44 Weaver Road, Unit 5233, Storrs, CT 06269-5233 (United States)

    2010-02-15

    A single PEMFC has been operated by varying the assembly temperature, the air dew point temperature and the anode/cathode stoichiometry rates with the aim to identify the parameters and combinations of factors affecting the cell performance. Some of the experiments were conducted with low humidified reactants (relative humidity of 12%). The FC characterizations tests have been conducted using in situ electrochemical methods based on load current and cell voltage signal analysis, namely: polarization curves, EIS measurements, cyclic and linear sweep voltammetries (CV and LSV). The impacts of the parameters on the global FC performances were observed using the polarization curves whereas EIS, CV and LSV test results were used to discriminate the different voltage loss sources. The test results suggest that some parameter sets allow maximal output voltages but can also induce material degradation. For instance, higher FC temperature and air flow values can induce significant electrical efficiency benefits, notably by increasing the reversible potential and the reaction kinetics. However, raising the cell temperature can also gradually dry the FC and increase the risk of membrane failure. LSV has also shown that elevated FC temperature and relative humidity can also accelerate the electrolyte degradation (i.e. slightly higher fuel crossover rate) and reduce the lifetime consequently. (author)

  7. Study of temperature, air dew point temperature and reactant flow effects on proton exchange membrane fuel cell performances using electrochemical spectroscopy and voltammetry techniques

    Science.gov (United States)

    Wasterlain, S.; Candusso, D.; Hissel, D.; Harel, F.; Bergman, P.; Menard, P.; Anwar, M.

    A single PEMFC has been operated by varying the assembly temperature, the air dew point temperature and the anode/cathode stoichiometry rates with the aim to identify the parameters and combinations of factors affecting the cell performance. Some of the experiments were conducted with low humidified reactants (relative humidity of 12%). The FC characterizations tests have been conducted using in situ electrochemical methods based on load current and cell voltage signal analysis, namely: polarization curves, EIS measurements, cyclic and linear sweep voltammetries (CV and LSV). The impacts of the parameters on the global FC performances were observed using the polarization curves whereas EIS, CV and LSV test results were used to discriminate the different voltage loss sources. The test results suggest that some parameter sets allow maximal output voltages but can also induce material degradation. For instance, higher FC temperature and air flow values can induce significant electrical efficiency benefits, notably by increasing the reversible potential and the reaction kinetics. However, raising the cell temperature can also gradually dry the FC and increase the risk of membrane failure. LSV has also shown that elevated FC temperature and relative humidity can also accelerate the electrolyte degradation (i.e. slightly higher fuel crossover rate) and reduce the lifetime consequently.

  8. Effect of aluminum and silicon reactants and process parameters on glass-ceramic waste form characteristics for immobilization of high-level fluorinel-sodium calcined waste

    International Nuclear Information System (INIS)

    Vinjamuri, K.

    1993-06-01

    In this report, the effects of aluminum and silicon reactants, process soak time and the initial calcine particle size on glass-ceramic waste form characteristics for immobilization of the high-level fluorinel-sodium calcined waste stored at the Idaho Chemical Processing Plant (ICPP) are investigated. The waste form characteristics include density, total and normalized elemental leach rates, and microstructure. Glass-ceramic waste forms were prepared by hot isostatically pressing (HIPing) a pre-compacted mixture of pilot plant fluorinel-sodium calcine, Al, and Si metal powders at 1050 degrees C, 20,000 psi for 4 hours. One of the formulations with 2 wt % Al was HIPed for 4, 8, 16 and 24 hours at the same temperature and pressure. The calcine particle size range include as calcined particle size smaller than 600 μm (finer than -30 mesh, or 215 μm Mass Median Diameter, MMD) and 180 μm (finer than 80 mesh, or 49 μm MMD)

  9. Nuclear spin and isospin excitations

    International Nuclear Information System (INIS)

    Osterfeld, F.

    1992-01-01

    A review is given of our present knowledge of collective spin-isospin excitations in nuclei. Most of this knowledge comes from intermediate-energy charge-exchange reactions and from inelastic electron- and proton-scattering experiments. The nuclear-spin dynamics is governed by the spin-isospin-dependent two-nucleon interaction in the medium. This interaction gives rise to collective spin modes such as the giant Gamow-Teller resonances. An interesting phenomenon is that the measured total Gamow-Teller transition strength in the resonance region is much less than a model-independent sum rule predicts. Two physically different mechanisms have been discussed to explain this so-called quenching of the total Gamow-Teller strength: coupling to subnuclear degrees of freedom in the form of Δ-isobar excitation and ordinary nuclear configuration mixing. Both detailed nuclear structure calculations and extensive analyses of the scattering data suggest that the nuclear configuration mixing effect is the more important quenching mechanism, although subnuclear degrees of freedom cannot be ruled out. The quenching phenomenon occurs for nuclear-spin excitations at low excitation energies (ω∼10--20 MeV) and small-momentum transfers (q≤0.5 fm -1 ). A completely opposite effect is anticipated in the high (ω,q)-transfer region (0≤ω≤500 MeV, 0.5≤q≤3 fm -1 ). The nuclear spin-isospin response might be enhanced due to the attractive pion field inside the nucleus. Charge-exchange reactions at GeV incident energies have been used to study the quasifree peak region and the Δ-resonance region. An interesting result of these experiments is that the Δ excitation in the nucleus is shifted downwards in energy relative to the Δ excitation of the free proton

  10. Internal voltage control of hydrogen-oxygen fuel cells: Feasibility study

    Science.gov (United States)

    Prokopius, P. R.

    1975-01-01

    An experimental study was conducted to assess the feasibility of internal voltage regulation of fuel cell systems. Two methods were tested. In one, reactant partial pressure was used as the voltage control parameter and in the other reactant total pressure was used for control. Both techniques were breadboarded and tested on a single alkaline-electrolyte fuel cell. Both methods were found to be possible forms of regulation, however, of the two the total pressure technique would be more efficient, simpler to apply and would provide better transient characteristics.

  11. Nuclear excitation in muonic gold

    CERN Document Server

    Robert Tissot, B; Debrunner, P; Engfer, R; Link, R; Schellenberg, L; Schneuwly, H; Walter, H K

    1973-01-01

    Energies and intensities of muonic X-rays in gold were measured at the CERN muon channel with an experimental set-up as described by Backe et al. (1972). The 2p-1s and 3d-2p transitions could only be analysed taking into account beside the static quadrupole interaction a dynamical hyperfine interaction of the 2p states, which leads to an excitation of the first four nuclear levels. The dynamical hyperfine interaction was calculated using the core excitation model (de Shalit, (1961)). (0 refs).

  12. Entanglement entropy of excited states

    International Nuclear Information System (INIS)

    Alba, Vincenzo; Fagotti, Maurizio; Calabrese, Pasquale

    2009-01-01

    We study the entanglement entropy of a block of contiguous spins in excited states of spin chains. We consider the XY model in a transverse field and the XXZ Heisenberg spin chain. For the latter, we developed a numerical application of the algebraic Bethe ansatz. We find two main classes of states with logarithmic and extensive behavior in the dimension of the block, characterized by the properties of excitations of the state. This behavior can be related to the locality properties of the Hamiltonian having a given state as the ground state. We also provide several details of the finite size scaling

  13. Autoresonant Excitation of Antiproton Plasmas

    CERN Document Server

    Andresen, Gorm B; Baquero-Ruiz, Marcelo; Bertsche, William; Bowe, Paul D; Butler, Eoin; Carpenter, P T; Cesar, Claudio L; Chapman, Steven; Charlton, Michael; Fajans, Joel; Friesen, Tim; Fujiwara, Makoto C; Gill, David R; Hangst, Jeffrey S; Hardy, Walter N; Hayden, Michael E; Humphries, Andrew J; Hurt, J L; Hydomako, Richard; Jonsell, Svante; Madsen, Niels; Menary, Scott; Nolan, Paul; Olchanski, Konstantin; Olin, Art; Povilus, Alexander; Pusa, Petteri; Robicheaux, Francis; Sarid, Eli; Silveira, Daniel M; So, Chukman; Storey, James W; Thompson, Robert I; van der Werf, Dirk P; Wurtele, Jonathan S; Yamazaki, Yasunori

    2011-01-01

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

  14. Coulomb excitation of 189Os

    International Nuclear Information System (INIS)

    Brandao, S.B.

    1987-01-01

    The level structure of 189 Os has been studied by Coulomb excitation using 35 Cl, 28 Si, 16 O beams. GOSIA, a code written to analyze multiple Coulomb excitation, was used to obtain the reduced probabilities of transition B(E2). The results for interband and intraband turned out possible the classification of the states following Nilsson levels. Gamma-rays originating from deexcitation of 216.7 and 219.4 keV have been separated and the reduced probability of transition has been measured. (A.C.A.S.) [pt

  15. Laser excitation spectroscopy of uranium

    International Nuclear Information System (INIS)

    Solarz, R.W.

    1976-01-01

    Laser excitation spectroscopy, recently applied to uranium enrichment research at LLL, has produced a wealth of new and vitally needed information about the uranium atom and its excited states. Among the data amassed were a large number of cross sections, almost a hundred radiative lifetimes, and many level assignments. Rydberg states, never before observed in uranium or any of the actinides, have been measured and cataloged. This work puts a firm experimental base under laser isotope separation, and permits a choice of the laser frequencies most appropriate for practical uranium enrichment

  16. Quenching reactions of electronically excited atoms

    International Nuclear Information System (INIS)

    Setser, D.W.

    2001-01-01

    The two-body, thermal quenching reactions of electronically excited atoms are reviewed using excited states of Ar, Kr, and Xe atoms as examples. State-specific interstate relaxation and excitation-transfer reactions with atomic colliders are discussed first. These results then are used to discuss quenching reactions of excited-state atoms with diatomic and polyatomic molecules, the latter have large cross sections, and the reactions can proceed by excitation transfer and by reactive quenching. Excited states of molecules are not considered; however, a table of quenching rate constants is given for six excited-state molecules in an appendix

  17. Ultrafast excited-state dynamics of 2,5-dimethylpyrrole.

    Science.gov (United States)

    Yang, Dongyuan; Min, Yanjun; Chen, Zhichao; He, Zhigang; Yuan, Kaijun; Dai, Dongxu; Yang, Xueming; Wu, Guorong

    2018-04-17

    The ultrafast excited-state dynamics of 2,5-dimethylpyrrole following excitation at wavelengths in the range of 265.7-216.7 nm is studied using the time-resolved photoelectron imaging method. It is found that excitation at longer wavelengths (265.7-250.2 nm) results in the population of the S1(1πσ*) state, which decays out of the photoionization window in about 90 fs. At shorter pump wavelengths (242.1-216.7 nm), the assignments are less clear-cut. We tentatively assign the initially photoexcited state(s) to the 1π3p Rydberg state(s) which has lifetimes of 159 ± 20, 125 ± 15, 102 ± 10 and 88 ± 10 fs for the pump wavelengths of 242.1, 238.1, 232.6 and 216.7 nm, respectively. Internal conversion to the S1(1πσ*) state represents at most a minor decay channel. The methyl substitution effects on the decay dynamics of the excited states of pyrrole are also discussed. Methyl substitution on the pyrrole ring seems to enhance the direct internal conversion from the 1π3p Rydberg state to the ground state, while methyl substitution on the N atom has less influence and the internal conversion to the S1(πσ*) state represents a main channel.

  18. The momentum transfer dependence of double excitations of helium

    International Nuclear Information System (INIS)

    Zhu Lin-Fan; Liu Xiao-Jing; Yuan Zhen-Sheng; Xu Ke-Zun

    2005-01-01

    The momentum transfer dependence of fundamental double excitation processes of helium is studied with high resolution and fast electron impact. It elucidates the dynamical correlations, in terms of internal correlation quantum numbers, K, T and A. The Fano profile parameters q, f a , ρ 2 , f and S of doubly excited states 2 (1,0) 2 +1se , 2 (0,1) 2 +1p0 and 2 (1,0) 2 +1De are determined as functions of momentum transfer K 2 . (author)

  19. Calibrated Noncontact Exciters for Optical Modal Analysis

    Directory of Open Access Journals (Sweden)

    Henrik O. Saldner

    1996-01-01

    Full Text Available Two types of exciters were investigated experimentally One of the exciters uses a small permanent magnet fastened on the object. The force is introduced by the change in the electromagnetic field from a coil via an air gap. The second exciter is an eddy-current electromagnet one. The amplitude of the forces from these exciters are calibrated by using dynamic reciprocity in conjunction with electronic holography. These forces strongly depend upon the distance between the exciter and the object.

  20. Gluonic excitations in hadronic spectroscopy

    International Nuclear Information System (INIS)

    Close, F.E.

    1983-09-01

    Theoretical expectations are described for new forms of hadronic matter containing gluons as excitable degrees of freedom. Particular attention is paid to hybrid states containing both quarks and gluons. Recent work on the spectroscopy of hybrid mesons and hybrid baryons is reviewed. Comparisons of bag model, lattice QCD and QCD sum rule predictions are made and some confrontation with data attempted. (author)

  1. Predictions for Excited Strange Baryons

    Energy Technology Data Exchange (ETDEWEB)

    Fernando, Ishara P.; Goity, Jose L. [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)

    2016-04-01

    An assessment is made of predictions for excited hyperon masses which follow from flavor symmetry and consistency with a 1/N c expansion of QCD. Such predictions are based on presently established baryonic resonances. Low lying hyperon resonances which do not seem to fit into the proposed scheme are discussed.

  2. Launch Excitement with Water Rockets

    Science.gov (United States)

    Sanchez, Juan Carlos; Penick, John

    2007-01-01

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

  3. High excitation ISM and gas

    NARCIS (Netherlands)

    Peeters, E; Martinez-Hernandez, NL; Rodriguez-Fernandez, NJ; Tielens, [No Value

    An overview is given of ISO results on regions of high excitation ISM and gas, i.e. H II regions, the Galactic Centre and Supernova Remnants. IR emission due to fine-structure lines, molecular hydrogen, silicates, polycyclic aromatic hydrocarbons and dust are summarised, their diagnostic

  4. High Excitation Gas and ISM

    Science.gov (United States)

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

    2004-01-01

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

  5. Electron excitation of alkali atoms

    International Nuclear Information System (INIS)

    Ormonde, S.

    1979-02-01

    The development and testing of a synthesized close-coupling effective model potential ten-channel electron-atom scattering code and some preliminary calculations of resonances in cross sections for the excitation of excited states of potassium by low energy electrons are described. The main results obtained are: identification of 1 S and 1 D structures in excitation cross sections below the 5 2 S threshold of neutral potassium; indications of additional structures - 1 P and 1 D between the 5 2 S and 5 2 D thresholds; and a suggested explanation of anomalously high interstate-electron impact excitation cross sections inferred from experiments on potassium-seeded plasmas. The effective potential model imbedded in the code can be used to simulate any atomic system that can be approximated by a single bound electron outside an ionic core. All that is needed is a set of effective potential parameters--experimental or theoretical. With minor modifications the code could be adapted to calculations of electron scattering by two-electron systems

  6. Proton exciting X ray analysis

    International Nuclear Information System (INIS)

    Ma Xinpei

    1986-04-01

    The analyzing capability of proton exciting X ray analysis for different elements in organisms was discussed, and dealing with examples of trace element analysis in the human body and animal organisms, such as blood serum, urine, and hair. The sensitivity, accuracy, and capability of multielement analysis were discussed. Its strong points for the trace element analysis in biomedicine were explained

  7. Manipulating charge transfer excited state relaxation and spin crossover in iron coordination complexes with ligand substitution

    DEFF Research Database (Denmark)

    Zhang, Wenkai; Kjær, Kasper Skov; Alonso-Mori, Roberto

    2017-01-01

    iron complexes with four cyanide (CN-;) ligands and one 2,2′-bipyridine (bpy) ligand. This enables MLCT excited state and metal-centered excited state energies to be manipulated with partial independence and provides a path to suppressing spin crossover. We have combined X-ray Free-Electron Laser (XFEL...... state lifetime of iron based complexes due to spin crossover-the extremely fast intersystem crossing and internal conversion to high spin metal-centered excited states. We revitalize a 30 year old synthetic strategy for extending the MLCT excited state lifetimes of iron complexes by making mixed ligand...

  8. Inhibition of light tunneling for multichannel excitations in longitudinally modulated waveguide arrays

    International Nuclear Information System (INIS)

    Lobanov, Valery E.; Vysloukh, Victor A.; Kartashov, Yaroslav V.

    2010-01-01

    We consider the evolution of multichannel excitations in longitudinally modulated waveguide arrays where the refractive index either oscillates out-of-phase in all neighboring waveguides or when it is modulated in phase in several central waveguides surrounded by out-of-phase oscillating neighbors. Both types of modulations allow resonant inhibition of light tunneling, but only the modulation of the latter type conserves the internal structure of multichannel excitations. We show that parameter regions where light tunneling inhibition is possible depend on the symmetry and structure of multichannel excitations. Antisymmetric multichannel excitations are more robust than their symmetric counterparts and experience nonlinearity-induced delocalization at higher amplitudes.

  9. Radiative and Excited State Charmonium Physics

    Energy Technology Data Exchange (ETDEWEB)

    Jozef Dudek

    2007-07-30

    Renewed interest in the spectroscopy of charmonium has arisen from recent unexpected observations at $e^+e^-$ colliders. Here we report on a series of works from the previous two years examining the radiative physics of charmonium states as well as the mass spectrum of states of higher spin and internal excitation. Using new techniques applied to Domain-Wall and Clover quark actions on quenched isotropic and anisotropic lattices, radiative transitions and two-photon decays are considered for the first time. Comparisons are made with experimental results and with model approaches. Forthcoming application to the light-quark sector of relevance to experiments like Jefferson Lab's GlueX is discussed.

  10. LAD Dissertation Prize Talk: Molecular Collisional Excitation in Astrophysical Environments

    Science.gov (United States)

    Walker, Kyle M.

    2017-06-01

    While molecular excitation calculations are vital in determining particle velocity distributions, internal state distributions, abundances, and ionization balance in gaseous environments, both theoretical calculations and experimental data for these processes are lacking. Reliable molecular collisional data with the most abundant species - H2, H, He, and electrons - are needed to probe material in astrophysical environments such as nebulae, molecular clouds, comets, and planetary atmospheres. However, excitation calculations with the main collider, H2, are computationally expensive and therefore various approximations are used to obtain unknown rate coefficients. The widely-accepted collider-mass scaling approach is flawed, and alternate scaling techniques based on physical and mathematical principles are presented here. The most up-to-date excitation data are used to model the chemical evolution of primordial species in the Recombination Era and produce accurate non-thermal spectra of the molecules H2+, HD, and H2 in a primordial cloud as it collapses into a first generation star.

  11. Excitation of solar and stellar oscillations

    International Nuclear Information System (INIS)

    Baudin, Frederic

    2009-01-01

    In this report for an Accreditation to Supervise Research (HDR), and after an introduction which outlines the potential of helio-seismology, the author addresses the problem of excitation and amplitude of stellar oscillations with respect to their most important aspects, i.e. the theoretical framework of the present understanding of excitation mechanisms, and instrumental influences on measurements which are used to assess excitation rates, the difficulty to perform these measurements, and their analysis in some various cases. Thus, the author addresses excitation mechanisms of stellar oscillation (stochastic excitation, opacity- related excitation, and other excitation mechanisms), the excitation of solar modes (observation and theoretical predictions, influence of magnetic phenomena, solar g modes), and the excitation of modes in other stars (solar-type pulsators, red giants, and not so conventional pulsators such as HD180642 and Be stars like HD49330)

  12. Excitations

    International Nuclear Information System (INIS)

    Dorner, B.

    1996-01-01

    A short introduction to instrumental resolution is followed by a discussion of visibilities of phonon modes due to their eigenvectors. High precision phonon dispersion curves in GaAs are presented together with 'ab initio' calculations. Al 2 O 3 is taken as an example of selected visibility due to group theory. By careful determination of phonon intensities eigenvectors can be determined, such as in Silicon and Diamond. The investigation of magnon modes is shown for the garnet Fe 2 Ca 3 (GeO 4 ) 3 , where also a quantum gap due to zero point spin fluctuations was observed. The study of the splitting of excitons in CsFeCl 3 in an applied magnetic field demonstrates the possibilities of neutron polarisation analysis, which made it possible to observe a mode crossing. An outlook to inelastic X-ray scattering with very high energy resolution of synchrotron radiation is given with the examples of phonons in Beryllium and in water. (author) 19 figs., 36 refs

  13. Localized excitations in superconducting point contacts: probing the Andreev doublet

    International Nuclear Information System (INIS)

    Bretheau, L.

    2013-01-01

    The Josephson effect describes the coherent coupling between superconductors and the resulting supercurrent. Microscopically, it arises from the existence of discrete quasiparticle states, localized at the weak link, the Andreev bound states. They come in doublets in each conduction channel of the weak link, with energies symmetric about the Fermi energy and opposite supercurrents. Each Andreev doublet gives rise to four states: the ground state |-> and the excited state |+>, with even parity, and the excited odd states |↑> and |↓>. Is it possible to address and control Andreev doublets? This thesis describes two sets of experiments designed to answer this question using the most basic Josephson element, a one-atom contact between two superconducting electrodes. In a first experiment, we have observed and characterized the excited odd states |↑> and |↓>. As expected for a spin-degenerate system, they do not carry supercurrent. In this experiment the excitation was uncontrolled and resulted from trapping of spurious quasiparticles. We have measured the lifetime of the odd states: under some condition, it is found to exceed 100 μs. The second experiment is a photon-absorption spectroscopy of the Andreev doublet. It was performed by using a Josephson junction as an integrated on-chip microwave emitter and detector. The observed Andreev transitions correspond to excitation from the ground state |->to the excited even state |+>, and are well accounted for by our quantum model. This result opens the way to coherent manipulation of this two level system. The direct observation of the excited Andreev state, either by quasiparticle-injection or photon-absorption, strongly supports the mesoscopic theory of the Josephson effect. It shows that in addition to the phase difference, each channel of a Josephson weak link possesses an internal fermionic degree of freedom. It could be used to code information in a novel type of superconducting qubit. (author) [fr

  14. Mean excitation energies for molecular ions

    Energy Technology Data Exchange (ETDEWEB)

    Jensen, Phillip W.K.; Sauer, Stephan P.A. [Department of Chemistry, University of Copenhagen, Copenhagen (Denmark); Oddershede, Jens [Department of Physics, Chemistry, and Pharmacy, University of Southern Denmark, Odense (Denmark); Quantum Theory Project, Departments of Physics and Chemistry, University of Florida, Gainesville, FL (United States); Sabin, John R., E-mail: sabin@qtp.ufl.edu [Department of Physics, Chemistry, and Pharmacy, University of Southern Denmark, Odense (Denmark); Quantum Theory Project, Departments of Physics and Chemistry, University of Florida, Gainesville, FL (United States)

    2017-03-01

    The essential material constant that determines the bulk of the stopping power of high energy projectiles, the mean excitation energy, is calculated for a range of smaller molecular ions using the RPA method. It is demonstrated that the mean excitation energy of both molecules and atoms increase with ionic charge. However, while the mean excitation energies of atoms also increase with atomic number, the opposite is the case for mean excitation energies for molecules and molecular ions. The origin of these effects is explained by considering the spectral representation of the excited state contributing to the mean excitation energy.

  15. Uniform magnetic excitations in nanoparticles

    DEFF Research Database (Denmark)

    Mørup, Steen; Hansen, Britt Rosendahl

    2005-01-01

    We have used a spin-wave model to calculate the temperature dependence of the (sublattice) magnetization of magnetic nanoparticles. The uniform precession mode, corresponding to a spin wave with wave vector q=0, is predominant in nanoparticles and gives rise to an approximately linear temperature...... dependence of the (sublattice) magnetization well below the superparamagnetic blocking temperature for both ferro-, ferri-, and antiferromagnetic particles. This is in accordance with the results of a classical model for collective magnetic excitations in nanoparticles. In nanoparticles of antiferromagnetic...... materials, quantum effects give rise to a small deviation from the linear temperature dependence of the (sublattice) magnetization at very low temperatures. The complex nature of the excited precession states of nanoparticles of antiferromagnetic materials, with deviations from antiparallel orientation...

  16. Receiver-exciter controller design

    Science.gov (United States)

    Jansma, P. A.

    1982-01-01

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

  17. Laser amplification in excited dielectrics

    Science.gov (United States)

    Winkler, Thomas; Haahr-Lillevang, Lasse; Sarpe, Cristian; Zielinski, Bastian; Götte, Nadine; Senftleben, Arne; Balling, Peter; Baumert, Thomas

    2018-01-01

    Wide-bandgap dielectrics such as glasses or water are transparent at visible and infrared wavelengths. This changes when they are exposed to ultrashort and highly intense laser pulses. Different interaction mechanisms lead to the appearance of various transient nonlinear optical phenomena. Using these, the optical properties of dielectrics can be controlled from the transparent to the metal-like state. Here we expand this range by a yet unexplored mechanism in excited dielectrics: amplification. In a two-colour pump-probe experiment, we show that a 400 nm femtosecond laser pulse is coherently amplified inside an excited sapphire sample on a scale of a few micrometres. Simulations strongly support the proposed two-photon stimulated emission process, which is temporally and spatially controllable. Consequently, we expect applications in all fields that demand strongly localized amplification.

  18. Vibrational excitation from heterogeneous catalysis

    International Nuclear Information System (INIS)

    Purvis, G.D. III; Redmon, M.J.; Woken, G. Jr.

    1979-01-01

    Classical trajectories have been used by numerous researchers to investigate the dynamics of exothermic chemical reactions (atom + diatom) with a view toward understanding what leads to vibrational excitation of the product molecule. Unlike these studies, the case where the reaction is catalyzed by a solid surface is considered. The trajectory studies indicate that there should be conditions under which considerable vibrational energy appears in the product molecules without being lost to the solid during the course of the reaction. 2 figures, 3 tables

  19. Magnetic excitations in thulium metal

    International Nuclear Information System (INIS)

    Fernandez-Baca, J.A.; Nicklow, R.M.; Rhyne, J.J.

    1989-01-01

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

  20. Isotope separation using vibrationally excited molecules

    International Nuclear Information System (INIS)

    1979-01-01

    This invention relates to isotope separation employing isotopically selective vibrational excitation and vibration-translation reactions of the excited particles. Uranium enrichment, using uranium hexafluoride, is a particular embodiment. (U.K.)

  1. Spurious Excitations in Semiclassical Scattering Theory.

    Science.gov (United States)

    Gross, D. H. E.; And Others

    1980-01-01

    Shows how through proper handling of the nonuniform motion of semiclassical coordinates spurious excitation terms are eliminated. An application to the problem of nuclear Coulomb excitation is presented as an example. (HM)

  2. Sub-50 fs excited state dynamics of 6-chloroguanine upon deep ultraviolet excitation.

    Science.gov (United States)

    Mondal, Sayan; Puranik, Mrinalini

    2016-05-18

    The photophysical properties of natural nucleobases and their respective nucleotides are ascribed to the sub-picosecond lifetime of their first singlet states in the UV-B region (260-350 nm). Electronic transitions of the ππ* type, which are stronger than those in the UV-B region, lie at the red edge of the UV-C range (100-260 nm) in all isolated nucleobases. The lowest energetic excited states in the UV-B region of nucleobases have been investigated using a plethora of experimental and theoretical methods in gas and solution phases. The sub-picosecond lifetime of these molecules is not a general attribute of all nucleobases but specific to the five primary nucleobases and a few xanthine and methylated derivatives. To determine the overall UV photostability, we aim to understand the effect of more energetic photons lying in the UV-C region on nucleobases. To determine the UV-C initiated photophysics of a nucleobase system, we chose a halogen substituted purine, 6-chloroguanine (6-ClG), that we had investigated previously using resonance Raman spectroscopy. We have performed quantitative measurements of the resonance Raman cross-section across the Bb absorption band (210-230 nm) and constructed the Raman excitation profiles. We modeled the excitation profiles using Lee and Heller's time-dependent theory of resonance Raman intensities to extract the initial excited state dynamics of 6-ClG within 30-50 fs after photoexcitation. We found that imidazole and pyrimidine rings of 6-ClG undergo expansion and contraction, respectively, following photoexcitation to the Bb state. The amount of distortions of the excited state structure from that of the ground state structure is reflected by the total internal reorganization energy that is determined at 112 cm(-1). The contribution of the inertial component of the solvent response towards the total reorganization energy was obtained at 1220 cm(-1). In addition, our simulation also yields an instantaneous response of the first

  3. Backreaction of excitations on a vortex

    OpenAIRE

    Arodz, Henryk; Hadasz, Leszek

    1996-01-01

    Excitations of a vortex are usually considered in a linear approximation neglecting their backreaction on the vortex. In the present paper we investigate backreaction of Proca type excitations on a straightlinear vortex in the Abelian Higgs model. We propose exact Ansatz for fields of the excited vortex. From initial set of six nonlinear field equations we obtain (in a limit of weak excitations) two linear wave equations for the backreaction corrections. Their approximate solutions are found ...

  4. Excitation system testing in HPP 'Uvac'

    Directory of Open Access Journals (Sweden)

    Milojčić Nemanja

    2011-01-01

    Full Text Available The excitation system of hydro unit in HPP 'Uvac' and results of testings of excitation system performed for achieving of unit's mathematical model are presented in this paper. Description of excitation system equipment, parameters of regulators and results obtained after testings are presented. The presented results showed that the regulators are properly adjusted and that the excitation system is completely functional and reliable.

  5. Effect of Reactant Concentration on the Microstructure of SiC Nano wires Grown In Situ within SiC Fiber Preforms

    International Nuclear Information System (INIS)

    Kim, Weon Ju; Kang, Seok Min; Park, Ji Yeon; Ryu, Woo Seog

    2006-01-01

    Silicon carbide fiber-reinforced silicon carbide matrix (SiC f /SiC) composites are considered as advanced materials for control rods and other in-core components of high-temperature gas cooled reactors. Although the carbon fiber-reinforced carbon matrix (C f /C) composites are more mature and have advantages in cost, manufacturability and some thermomechanical properties, the SiC f /SiC composites have a clear advantage in irradiation stability, specifically a lower level of swelling and retention of mechanical properties. This offers a lifetime component for control rod application to HTGRs while the Cf/C composites would require 2-3 replacements over the reactor lifetime. In general, the chemical vapor infiltration (CVI) technique has been used most widely to produce SiC f /SiC composites. Although the technique produces a highly pure SiC matrix, it requires a long processing time and inevitably contains large interbundle pores. The present authors have recently developed 'whisker growing-assisted process,' in which one-dimensional SiC nano structures with high aspect ratios such as whiskers, nano wires and nano rods are introduced into the fiber preform before the matrix infiltration step. This novel method can produce SiC f /SiC composites with a lower porosity and an uniform distribution of pores when compared with the conventional CVI. This would be expected to increase mechanical and thermal properties of the SiC f /SiC composites. In order to take full advantage of the whisker growing strategy, however, a homogeneous growth of long whiskers is required. In this study, we applied the atmospheric pressure CVI process without metallic catalysts for the growth of SiC nano wires within stacked SiC fiber fabrics. We focused on the effect of the concentration of a reactant gas on the growth behavior and microstructures of the SiC nano wires and discussed a controlling condition for the homogenous growth of long SiC nano wires

  6. Tuning different kinds of entangled metal-organic frameworks by modifying the spacer group of aliphatic dicarboxylate ligands and the reactant ratio.

    Science.gov (United States)

    Yang, Jin-Xia; Zhai, Ji-Quan; Zhang, Xin; Qin, Ye-Yan; Yao, Yuan-Gen

    2016-01-14

    Taking advantage of the conformational flexibility of the bpp ligand and aliphatic dicarboxylic acids, six interesting entangled coordination polymers, {[Cd(fum)(bpp)(H2O)]·(H2O)}n (), {[Cd(fum)(bpp)2]·(H2O)5}n (), {[Cd2(suc)1.5(bpp)2(NO3)(H2O)2]·6H2O}n (), {[Cd(suc)(bpp)2]·(H2O)1.5}n (), {[Cd2(glu)2(bpp)3]·10H2O}n (), and {Cd(adp)(bpp)(H2O)}n () have been prepared and structurally characterized (bpp = 1,3-bi(4-pyridyl)propane, fum = fumaric, suc = succinate, glu = glutaric, adp = adipic). Compounds and are comprised of undulated 2D 4(4)-sql networks. In the structure of compound , two identical undulated layers are parallelly interpenetrated with each other to give a 2D → 2D interpenetrating framework. For , the dangling arms projected from 2D layers are intercalated into the neighboring sheets, producing a 2D → 3D polythreading framework. Compound shows a rare example of a 2D self-penetrating framework with a (3,4)-connected (4(2)·6(3)·8)(4(2)·6) topology. Compound presents an unusual 2D self-threading network with a novel 4-connected {4(2)·6(3)·8} topology. Compound displays a 3D self-penetrating system based on a 2D → 3D parallel polycatenation array. Compound exhibits an unprecedented 3D self-penetrating structure having both 1D + 1D → 1D polycatenation and 3D + 3D → 3D interpenetration characteristics. A comparison of these six compounds demonstrates that both the different spacer lengths of the aliphatic dicarboxylates and reactant ratios appear to play a significant role in the assembly of entangled frameworks. In addition, thermal stabilities and photoluminescence properties of have been examined in the solid state at room temperature.

  7. Two series of reactant's ratio-dependent lanthanide organic frameworks derived from nicotinic acid N-oxide and oxalate: synthesis, crystal structures and luminescence properties.

    Science.gov (United States)

    Yu, Yanyan; Zhang, Lijuan; Zhou, Yunshan; Zuhra, Zareen

    2015-03-14

    Two series of lanthanide(III)–organic frameworks with the molecular formula [Ln2(NNO)2(OX)2(H2O)4]n (Ln = Eu 1, Tb 2, Sm 3, Dy 4, Gd 5) and [Ln2(NNO)4(OX)(H2O)2]n (Ln = Eu 6, Tb 7, Sm 8, Dy 9, Gd 10) were synthesized successfully under the same hydrothermal conditions with nicotinic N-oxide (HNNO) and oxalic acid (H2OX) as the mixed ligands merely through varying the molar ratio of the reactants. The compounds were characterized by IR, elemental analysis, UV, TG-DTA and powder X-ray diffraction (XRD). X-ray single-crystal diffraction analyses of compounds 1 and 7 selected as representatives and powder XRD analysis of the compounds revealed that both the series of compounds feature three-dimensional (3-D) open frameworks, and crystallize in the triclinic P1 space group while with different unit cell parameters. In compound 1, pairs of Eu(3+) ions and pairs of NNO(−) ligands connect with each other alternately to form a 1-D infinite Eu-NNO double chain, the adjacent 1-D double-chains are then joined together through OX(2−) ligands leading to a 2D layer, the 2-D layers are further ‘pillared’ by OX(2−) ligands resulting in a 3-D framework. In compound 7, the 1-D Tb-NNO infinite chain and its 2-D layer are formed in an almost similar fashion to that in compound 1. The difference between the structures of the two compounds 1 and 7 is that the adjacent 2-D layers in compound 7 are further connected by NNO(−) ligands resulting in a 3-D framework. The photoluminescence properties and energy transfer mechanism of the compounds were studied systematically. The energy level of the lowest triplet states of the HNNO ligand (23148 cm(−1)) was determined based on the phosphorescence spectrum of compound 5 at 77 K. The (5)D0 (Eu(3+)) and (5)D4 (Tb(3+)) emission lifetimes are 0.46 ms, 0.83 ms, 0.69 ms and 0.89 ms and overall quantum yields are 1.03%, 3.29%, 2.58% and 3.78% for the compounds 1, 2, 6 and 7, respectively.

  8. Renewable synthesis-gas-production. Do hydrocarbons in the reactant flow of the reverse water-gas shift reaction cause coke formation?

    Energy Technology Data Exchange (ETDEWEB)

    Wolf, A.; Kern, C.; Jess, A. [Bayreuth Univ. (Germany). Dept. of Chemical Engineering

    2013-11-01

    In a two-step synthetic fuel production process based on carbon dioxide and renewable hydrogen, the best possible selectivity towards liquid hydrocarbons (Hc) shall be implemented. The process consists of a combination of the Reverse Water-Gas Shift reaction and the Fischer-Tropsch synthesis. To achieve this goal, gaseous short-chained Hc from the FTS reactor are recycled in the RWGS unit. In this paper, challenges coming up with the implementation of a recycle loop are discussed. First of all, it has to be examined whether Hc are converted under conditions present in the RWGS reactor. The coking caused by the recycle of Hc is regarded, including thermal coking in the heating zone of the reactor and catalytic coking in the catalyst bed. Coking of course is unwanted, as it deactivates the catalyst. The scope of this work is to find out to which extent and under which conditions gaseous Hc can be recycled. Therefore, experiments were carried out in both, a quartz glass reactor using a commercial Ni-catalyst at ambient pressure and in a pressurized steel reactor (without catalyst) to examine coking during the thermal decomposition of Hc. The catalytic experiments at atmospheric pressure showed that a recycle of CH{sub 4} did not cause coking up to a ratio of CH{sub 4}/CO{sub 2} below one. For these conditions, long term stability was proved. The reaction rates of the CH{sub 4} conversion were below those of the RWGS reaction. However, replacing CH{sub 4} by C{sub 3}H{sub 8} leads to thermal and catalytic coking. Catalytic coking hits the maximum level at about 700 C and decreases for higher temperatures and, thus is not regarded as a problem for the RWGS reactor. In contrast to that, thermal coking raises with higher temperatures, but it can be supressed efficiently with additional injection of H{sub 2}O, which of course shifts the equilibrium towards the undesired reactant side. (orig.)

  9. Single cyanide-bridged Mo(W)/S/Cu cluster-based coordination polymers: Reactant- and stoichiometry-dependent syntheses, effective photocatalytic properties

    International Nuclear Information System (INIS)

    Zhang, Jinfang; Wang, Chao; Wang, Yinlin; Chen, Weitao; Cifuentes, Marie P.; Humphrey, Mark G.; Zhang, Chi

    2015-01-01

    The systematic study on the reaction variables affecting single cyanide-bridged Mo(W)/S/Cu cluster-based coordination polymers (CPs) is firstly demonstrated. Five anionic single cyanide-bridged Mo(W)/S/Cu cluster-based CPs {[Pr_4N][WS_4Cu_3(CN)_2]}_n (1), {[Pr_4N][WS_4Cu_4(CN)_3]}_n (2), {[Pr_4N][WOS_3Cu_3(CN)_2]}_n (3), {[Bu_4N][WOS_3Cu_3(CN)_2]}_n (4) and {[Bu_4N][MoOS_3Cu_3(CN)_2]}_n (5) were prepared by varying the molar ratios of the starting materials, and the specific cations, cluster building blocks and central metal atoms in the cluster building blocks. 1 possesses an anionic 3D diamondoid framework constructed from 4-connected T-shaped clusters [WS_4Cu_3]"+ and single CN"− bridges. 2 is fabricated from 6-connected planar ‘open’ clusters [WS_4Cu_4]"2"+ and single CN"− bridges, forming an anionic 3D architecture with an “ACS” topology. 3 and 4 exhibit novel anionic 2-D double-layer networks, both constructed from nest-shaped clusters [WOS_3Cu_3]"+ linked by single CN"− bridges, but containing the different cations [Pr_4N]"+ and [Bu_4N]"+, respectively. 5 is constructed from nest-shaped clusters [MoOS_3Cu_3]"+ and single CN"− bridges, with an anionic 3D diamondoid framework. The anionic frameworks of 1-5, all sustained by single CN"− bridges, are non-interpenetrating and exhibit huge potential void volumes. Employing differing molar ratios of the reactants and varying the cluster building blocks resulted in differing single cyanide-bridged Mo(W)/S/Cu cluster-based CPs, while replacing the cation ([Pr_4N]"+ vs. [Bu_4N]"+) was found to have negligible impact on the nature of the architecture. Unexpectedly, replacement of the central metal atom (W vs. Mo) in the cluster building blocks had a pronounced effect on the framework. Furthermore, the photocatalytic activities of heterothiometallic cluster-based CPs were firstly explored by monitoring the photodegradation of methylene blue (MB) under visible light irradiation, which reveals that 2

  10. Continuum emission of excited sodium dimer

    International Nuclear Information System (INIS)

    Pardo, A.; Poyato, J.M.L.; Alonso, J.I.; Rico, F.R.

    1980-01-01

    A study has been made of the behaviour of excited molecular sodium using high-power Ar + laser radiation. A continuum emission was observed in the red wavelength region. This emission was thought to be caused by the formation of excited triatomic molecules. Energy transfer was observed from excited molecules to atoms. (orig.)

  11. Control of excitation in the fluorescence microscope.

    Science.gov (United States)

    Lea, D J; Ward, D J

    1979-01-01

    In fluorescence microscopy image brightness and contrast and the rate of fading depend upon the intensity of illumination of the specimen. An iris diaphragm or neutral density filters may be used to reduce fluorescence excitation. Also the excitation bandwidth may be varied by using a broad band exciter filter with a set of interchangeable yellow glass filters at the lamphouse.

  12. Production of excited charmed mesons at LEP

    CERN Document Server

    Abbaneo, D

    2000-01-01

    Studies od the production of orbitally excited charmed and charmed strange mesons in e+e- collisions, performed by the LEP collaborations are reviewed. Measurements of the production rates of orbitally excited charmed mesons in semileptonic b decays are presented. Searches for charmed meson radial excitations are also briefly discussed.

  13. Femtosecond laser excitation of dielectric materials

    DEFF Research Database (Denmark)

    Wædegaard, Kristian Juncher; Balling, Peter; Frislev, Martin Thomas

    2012-01-01

    We report an approach to modeling the interaction between ultrashort laser pulses and dielectric materials. The model includes the excitation of carriers by the laser through strongfield excitation, collisional excitation, and absorption in the plasma consisting of conduction-band electrons formed...

  14. Photoionization of excited molecular states using multiphoton excitation techniques

    International Nuclear Information System (INIS)

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

    1984-01-01

    Photoelectron spectra are reported for three photon resonant, four photon ionization of H 2 via the B 1 Σ/sub u/ + , v = 7 (J = 2,4) and C 1 π/sub u'/, v = 0-4 (J = 1) levels and of N 2 via the o 3 1 π/sub u'/, v = 1,2, b 1 π/sub u'/, v = 3-5, and c 1 π/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

  15. Photoionization of excited molecular states using multiphoton excitation techniques

    International Nuclear Information System (INIS)

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

    1984-01-01

    Photoelectron spectra are reported for three photon resonant, four photon ionization of H 2 via the B 1 Σ + /sub u/, v = 7 (J = 2,4) and C 1 Pi/sub u/, v = 0-4 (J = 1) levels and of N 2 via the o 3 1 Pi/sub u/, v = 1,2, b 1 Pi/sub u/, v = 3-5, and c 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

  16. Excited states in stochastic electrodynamics

    International Nuclear Information System (INIS)

    Franca, H.M.; Marshall, T.W.

    1987-12-01

    It is shown that the set of Wigner functions associated with the excited states of the harmonic oscillator constitute a complete set of functions over the phase space. An arbitraty distribution can be expanded in terms of these Wigner functions. By studying the time evolution, according to Stochastic Electrodynamics, of the expansion coefficients, becomes feasible to separate explicity the contributionsof the radiative reaction and the vaccuum field to the Einsten. A coefficients for this system. A simple semiclassical explanation of the Weisskopf-Heitler phenomenon in resonance fluorescence is also supplied. (author) [pt

  17. Hadron excitation of giant resonances

    International Nuclear Information System (INIS)

    Morsch, H.-P.

    1985-01-01

    A review is given on giant resonance studies in heavy nuclei using scattering of different hadronic probes. Concerning isoscalar giant resonances compression modes are discussed with the possibility to obtain more detailed structure information. From detailed studies of α scattering the distribution of isoscalar strengths of multipolarity up to L=6 was obtained. Some recent aspects of heavy ion excitation of collective modes are mentioned. The possibility to study isovector giant resonances in hadron charge exchange reactions is discussed. Finally, a comparison is made between α and 200 MeV proton scattering from which isoscalar and spin-isospin continuum response are extracted. (orig.)

  18. Magnetic excitations in ferromagnetic semiconductors

    International Nuclear Information System (INIS)

    Furdyna, J.K.; Liu, X.; Zhou, Y.Y.

    2009-01-01

    Magnetic excitations in a series of GaMnAs ferromagnetic semiconductor films were studied by ferromagnetic resonance (FMR). Using the FMR approach, multi-mode spin wave resonance spectra have been observed, whose analysis provides information on magnetic anisotropy (including surface anisotropy), distribution of magnetization precession within the GaMnAs film, dynamic surface spin pinning (derived from surface anisotropy), and the value of exchange stiffness constant D. These studies illustrate a combination of magnetism and semiconductor physics that is unique to magnetic semiconductors

  19. Laser amplification in excited dielectrics

    DEFF Research Database (Denmark)

    Winkler, Thomas; Haahr-Lillevang, Lasse; Sarpe, Cristian

    2018-01-01

    Wide-bandgap dielectrics such as glasses or water are transparent at visible and infrared wavelengths. This changes when they are exposed to ultrashort and highly intense laser pulses. Different interaction mechanisms lead to the appearance of various transient nonlinear optical phenomena. Using...... these, the optical properties of dielectrics can be controlled from the transparent to the metal-like state. Here we expand this range by a yet unexplored mechanism in excited dielectrics: amplification. In a two-colour pump-probe experiment, we show that a 400nm femtosecond laser pulse is coherently...

  20. Importance of being topologically excited

    International Nuclear Information System (INIS)

    Caldi, D.G.

    1980-08-01

    A class of Euclidean configurations that appear to be dominant in the functional integral of the CP/sup N-1/ models is identified. These configurations are point-like topological excitations, and they may be viewed as constituents of instantons, although they are defined independently of instantons through a continuum duality transformation. Not only do these configurations survive as N → infinity, but in the plasma phase they are responsible for the effects encountered within the 1/N expansion - confinement, theta dependence, and dynamical mass generation

  1. Excited state Intramolecular Proton Transfer in Anthralin

    DEFF Research Database (Denmark)

    Møller, Søren; Andersen, Kristine B.; Spanget-Larsen, Jens

    1998-01-01

    Quantum chemical calculations performed on anthralin (1,8-dihydroxy-9(10H)-anthracenone) predict the possibility of an excited-state intramolecular proton transfer process. Fluorescence excitation and emission spectra of the compound dissolved in n-hexane at ambient temperature results in an unus......Quantum chemical calculations performed on anthralin (1,8-dihydroxy-9(10H)-anthracenone) predict the possibility of an excited-state intramolecular proton transfer process. Fluorescence excitation and emission spectra of the compound dissolved in n-hexane at ambient temperature results......, associated with an excited-state intramolecular proton transfer process....

  2. Thermodynamical description of excited nuclei

    International Nuclear Information System (INIS)

    Bonche, P.

    1989-01-01

    In heavy ion collisions it has been possible to obtain composite systems at rather high excitation energies corresponding to temperatures of several MeV. The theoretical studies of these systems are based on concepts borrowed from thermodynamics or statistical physics, such as the temperature. In these lectures, we present the concepts of statistical physics which are involved in the physics of heavy ion as they are produced nowadays in the laboratory and also during the final stage of a supernova collapse. We do not attempt to describe the reaction mechanisms which yield such nuclear systems nor their decay by evaporation or fragmentation. We shall only study their static properties. The content of these lectures is organized in four main sections. The first one gives the basic features of statistical physics and thermodynamics necessary to understand quantum mechanics at finite temperature. In the second one, we present a study of the liquid-gas phase transition in nuclear physics. A phenomenological approach of the stability of hot nuclei follows. The microscopic point of view is proposed in the third part. Starting from the basic concepts derived in the first part, it provides a description of excited or hot nuclei which confirms the qualitative results of the second part. Furthermore it gives a full description of most properties of these nuclei as a function of temperature. Finally in the last part, a microscopic derivation of the equation of state of nuclear matter is proposed to study the collapse of a supernova core

  3. Nuclear excited power generation system

    International Nuclear Information System (INIS)

    Parker, R.Z.; Cox, J.D.

    1989-01-01

    A power generation system is described, comprising: a gaseous core nuclear reactor; means for passing helium through the reactor, the helium being excited and forming alpha particles by high frequency radiation from the core of the gaseous core nuclear reactor; a reaction chamber; means for coupling chlorine and hydrogen to the reaction chamber, the helium and alpha particles energizing the chlorine and hydrogen to form a high temperature, high pressure hydrogen chloride plasma; means for converting the plasma to electromechanical energy; means for coupling the helium back to the gaseous core nuclear reactor; and means for disassociating the hydrogen chloride to form molecular hydrogen and chlorine, to be coupled back to the reaction chamber in a closed loop. The patent also describes a power generation system comprising: a gaseous core nuclear reactor; means for passing hydrogen through the reactor, the hydrogen being excited by high frequency radiation from the core; means for coupling chlorine to a reaction chamber, the hydrogen energizing the chlorine in the chamber to form a high temperature, high pressure hydrogen chloride plasma; means for converting the plasma to electromechanical energy; means for disassociating the hydrogen chloride to form molecular hydrogen and chlorine, and means for coupling the hydrogen back to the gaseous core nuclear reactor in a closed loop

  4. Core excitation and de-excitation spectroscopies of free atoms and molecules

    International Nuclear Information System (INIS)

    Ueda, Kiyoshi

    2006-01-01

    This article provides a review of the current status of core excitation and de-excitation spectroscopy studies of free atoms molecules using a high-resolution soft X-ray monochromator and a high-resolution electron energy analyzer, installed in the soft X-ray photochemistry beam line at SPring-8. Experimental results are discussed for 1s excitation of Ne, O 1s excitation of CO and H 2 O, and F 1s excitation of CF 4 . (author)

  5. The effect of caffeine on the reactions of the excited singlet state of pyrene in micellar sodium lauryl sulfate

    Science.gov (United States)

    Hashimoto, Shuichi; Thomas, J. Kerry

    1984-08-01

    The effect of caffeine on a few photo-induced reactions of pyrene in micellar sodium lauryl sulfate (NaLS) has been studied. In these systems caffeine complexes with the pyrene (K asso = 85 ± 10 M -1 and also with the other reactants, e.g. Cu 2+ or TI +. The efficiencies of reactions which involve contact, i.e. pyrene excimer formation, and quenching by TI + ions to give the triplet state of pyrene, are significantly reduced in the presence of caffeine, due to geometric inhibitions formed by the complexation processes. The kinetics of photo-induced electron transfer, e.g. between excited pyrene and Cu 2+, are not affected. However, the subsequent reactions of the products are modified and the yield of ionic products is markedly increased.

  6. Single cyanide-bridged Mo(W)/S/Cu cluster-based coordination polymers: Reactant- and stoichiometry-dependent syntheses, effective photocatalytic properties

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Jinfang, E-mail: zjf260@jiangnan.edu.cn [China-Australia Joint Research Center for Functional Molecular Materials, School of Chemical and Material Engineering, Jiangnan University, Wuxi 214122 (China); Wang, Chao [China-Australia Joint Research Center for Functional Molecular Materials, School of Chemical and Material Engineering, Jiangnan University, Wuxi 214122 (China); Wang, Yinlin; Chen, Weitao [China-Australia Joint Research Center for Functional Molecular Materials, Scientific Research Academy, Jiangsu University, Zhenjiang 212013 (China); Cifuentes, Marie P.; Humphrey, Mark G. [Research School of Chemistry, Australian National University, Canberra ACT 0200 (Australia); Zhang, Chi, E-mail: chizhang@jiangnan.edu.cn [China-Australia Joint Research Center for Functional Molecular Materials, School of Chemical and Material Engineering, Jiangnan University, Wuxi 214122 (China)

    2015-11-15

    The systematic study on the reaction variables affecting single cyanide-bridged Mo(W)/S/Cu cluster-based coordination polymers (CPs) is firstly demonstrated. Five anionic single cyanide-bridged Mo(W)/S/Cu cluster-based CPs {[Pr_4N][WS_4Cu_3(CN)_2]}{sub n} (1), {[Pr_4N][WS_4Cu_4(CN)_3]}{sub n} (2), {[Pr_4N][WOS_3Cu_3(CN)_2]}{sub n} (3), {[Bu_4N][WOS_3Cu_3(CN)_2]}{sub n} (4) and {[Bu_4N][MoOS_3Cu_3(CN)_2]}{sub n} (5) were prepared by varying the molar ratios of the starting materials, and the specific cations, cluster building blocks and central metal atoms in the cluster building blocks. 1 possesses an anionic 3D diamondoid framework constructed from 4-connected T-shaped clusters [WS{sub 4}Cu{sub 3}]{sup +} and single CN{sup −} bridges. 2 is fabricated from 6-connected planar ‘open’ clusters [WS{sub 4}Cu{sub 4}]{sup 2+} and single CN{sup −} bridges, forming an anionic 3D architecture with an “ACS” topology. 3 and 4 exhibit novel anionic 2-D double-layer networks, both constructed from nest-shaped clusters [WOS{sub 3}Cu{sub 3}]{sup +} linked by single CN{sup −} bridges, but containing the different cations [Pr{sub 4}N]{sup +} and [Bu{sub 4}N]{sup +}, respectively. 5 is constructed from nest-shaped clusters [MoOS{sub 3}Cu{sub 3}]{sup +} and single CN{sup −} bridges, with an anionic 3D diamondoid framework. The anionic frameworks of 1-5, all sustained by single CN{sup −} bridges, are non-interpenetrating and exhibit huge potential void volumes. Employing differing molar ratios of the reactants and varying the cluster building blocks resulted in differing single cyanide-bridged Mo(W)/S/Cu cluster-based CPs, while replacing the cation ([Pr{sub 4}N]{sup +} vs. [Bu{sub 4}N]{sup +}) was found to have negligible impact on the nature of the architecture. Unexpectedly, replacement of the central metal atom (W vs. Mo) in the cluster building blocks had a pronounced effect on the framework. Furthermore, the photocatalytic activities of heterothiometallic

  7. Search for nuclear excitation by laser-driven electron motion

    International Nuclear Information System (INIS)

    Bounds, J.A.; Dyer, P.

    1992-01-01

    It has been proposed that a nucleus may be excited by first exciting the atom's electrons with UV photons. The incident photons couple to the electrons, which would then couple via a virtual photon to the nucleus. As a test case, experiments with 235 U have been performed. A pulsed infrared laser produces an atomic vapor of 235 U which is then bombarded by a high-brightness UV laser beam. The resulting ions are collected. The first excited nuclear state of 235 U has a 26-min half-life and decays by internal conversion, resulting in emission of an atomic electron. These conversion electrons are detected by a channel electron multiplier. An upper limit of 4.0x10 -5 has been obtained for the probability of exciting the nucleus of a 235 U atom that is in the 248-nm UV beam for 700 fs at an irradiance in the range of 1.0x10 15 to 2.5x10 15 W/cm 2

  8. Internal conversion mediated by specific nuclear motions

    DEFF Research Database (Denmark)

    Klein, Liv Bærenholdt; Sølling, Theis Ivan

    2014-01-01

    the excitation energies, and the excitation in all cases is by a 200 nm photon, the S1 density-of-states in the Franck-Condon region will be high for the more N-alkylated amine. This, according to standard models, should lead to faster internal conversion. The experimental results are in contrast to this...

  9. Microwave Excitation In ECRIS plasmas

    International Nuclear Information System (INIS)

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

    2007-01-01

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

  10. Excited levels of Pa-233

    International Nuclear Information System (INIS)

    Vara Cuadrado, J. M.

    1969-01-01

    A study of Pa-233 excited levels from the alpha decay of Np-237 and from beta decay of Th-233 has been performed. The alpha decay spectrum was measured with a semiconductor spectrometer of 18 keV effective resolution (FWHM). Over 13 new lines were identified. The gamma ray spectra of Np-237 and Th-233 were obtained with a Ge-Li detector low and medium range energy lines, and with Si-Li detector for the low energy region. A continuous purification method of Np-237 from its comparatively short-lived daughter Pa-233 was applied. A high number of new lines were identified in both spectra. The gamma-gamma coincidence spectra were obtained with INa(T 1 ) detectors. (Author) 54 refs

  11. Quantized wobbling excitations with alignments

    International Nuclear Information System (INIS)

    Hamamoto, Ikuko; Hagemann, Gudrun B.

    2003-01-01

    The wobbling excitations in the presence of an appreciable amount of alignment are expected to appear more easily at lower angular momenta of the yrast spectra, compared with those in the textbook example. The large B(E2;I→I-1) value for Δn=1 transitions where n expresses the number of wobbling phonons is shown to be a strongly increasing function of the triaxiality parameter γ, especially for γ > or approx. +20 deg., while it is relatively independent of moments of inertia. On the other hand, the relation of the wobbling phonon energy to the total angular momentum may be used to extract quantitative information on nuclear moments of inertia. It is concluded that the γ value of the triaxial, strongly deformed bands in 163 Lu is about equal to +20 deg. and may be slightly increasing as a function of I

  12. Resonantly enhanced production of excited fragments of gaseous molecules following core-level excitation

    International Nuclear Information System (INIS)

    Chen, J.M.; Lu, K.T.; Lee, J.M.; Ho, S.C.; Chang, H.W.; Lee, Y.Y.

    2005-01-01

    State-selective dissociation dynamics for the excited fragments of gaseous Si(CH 3 ) 2 Cl 2 following Cl 2p and Si 2p core-level excitations have been investigated by resonant photoemission spectroscopy and dispersed UV/optical fluorescence spectroscopy. The main features in the gaseous Si(CH 3 ) 2 Cl 2 fluorescence spectrum are identified as the emission from excited Si*, Si + *, CH* and H*. The core-to-Rydberg excitations at both Si 2p and Cl 2p edges lead to a noteworthy production of not only the excited atomic fragments, neutral and ionic (Si*, Si + *) but also the excited diatomic fragments (CH*). In particular, the excited neutral atomic fragments Si* are significantly reinforced. The experimental results provide deeper insight into the state-selective dissociation dynamics for the excited fragments of molecules via core-level excitation

  13. International Trade. International Business

    OpenAIRE

    Мохнюк, А. М.; Mokhniuk, A. M.

    2015-01-01

    Work programme of the study course “International Trade. International Business” was prepared in accordance with educational and vocational training program for bachelors of training direction 6.030601 “Management”.

  14. Deciphering excited state evolution in halorhodopsin with stimulated emission pumping.

    Science.gov (United States)

    Bismuth, Oshrat; Komm, Pavel; Friedman, Noga; Eliash, Tamar; Sheves, Mordechai; Ruhman, Sanford

    2010-03-04

    The primary photochemical dynamics of Hb. pharaonis Halorhodopsin (pHR) are investigated by femtosecond visible pump-near IR dump-hyperspectral probe spectroscopy. The efficiency of excited state depletion is deduced from transient changes in absorption, recorded with and without stimulated emission pumping (SEP), as a function of the dump delay. The concomitant reduction of photocycle population is assessed by probing the "K" intermediate difference spectrum. Results show that the cross section for stimulating emission is nearly constant throughout the fluorescent state lifetime. Probing "K" demonstrates that dumping produces a proportionate reduction in photocycle yields. We conclude that, despite its nonexponential internal conversion (IC) kinetics, the fluorescent state in pHR constitutes a single intermediate in the photocycle. This contrasts with conclusions drawn from the study of primary events in the related chloride pump from Hb. salinarum (sHR), believed to produce the "K" intermediate from a distinct short-lived subpopulation in the excited state. Our discoveries concerning internal conversion dynamics in pHR are discussed in light of recent expectations for similar excited state dynamics in both proteins.

  15. Back reaction of excitations on a vortex

    International Nuclear Information System (INIS)

    Arodz, H.; Hadasz, L.

    1997-01-01

    Excitations of a vortex are usually considered in a linear approximation neglecting their back reaction on the vortex. In the present paper we investigate back reaction of Proca-type excitations on a straight linear vortex in the Abelian Higgs model. We propose an exact ansatz for fields of the excited vortex. From an initial set of six nonlinear field equations we obtain (in a limit of weak excitations) two linear wave equations for the back reaction corrections. Their approximate solutions are found in the cases of plane wave and wave-packet-type excitations. We find that the excited vortex radiates the vector field and that the Higgs field has a very broad oscillating component. copyright 1997 The American Physical Society

  16. Back reaction of excitations on a vortex

    Science.gov (United States)

    Arodź, Henryk; Hadasz, Leszek

    1997-01-01

    Excitations of a vortex are usually considered in a linear approximation neglecting their back reaction on the vortex. In the present paper we investigate back reaction of Proca-type excitations on a straight linear vortex in the Abelian Higgs model. We propose an exact ansatz for fields of the excited vortex. From an initial set of six nonlinear field equations we obtain (in a limit of weak excitations) two linear wave equations for the back reaction corrections. Their approximate solutions are found in the cases of plane wave and wave-packet-type excitations. We find that the excited vortex radiates the vector field and that the Higgs field has a very broad oscillating component.

  17. Orientation of nuclei excited by polarized neutrons

    International Nuclear Information System (INIS)

    Lifshits, E.P.

    1986-01-01

    Polarization and radiation angular distribution of oriented nuclei in inelastic scattering of polarized neutrons were investigated. Nucleus orientation in the final state was described by polarization density matrix (PDM). If PDM is known, angular distributions, linear and circular polarization of γ-quanta emitted by a nucleus can be determined. Analytical expression for PDM, conditions of its diagonalization in the case of direct nucleus excitation and excitation by the stage of compound nucleus were obtained. Orientation of 12 C nuclei in the excited state 4.439 MeV, 2 + at energy of incident neutrons in the laboratory system from 4.8 MeV (excitation threshold) upt to 9 MeV was calculated as an example. Neutrons in initial state are completely polarized along Z axis. Calculations showed that excitation proceeds mainly by the stage of compound nucleus formation and 12 C nucleus is highly polarized in excited state

  18. The EDDA experiment: proton-proton elastic scattering excitation functions at intermediate energies

    International Nuclear Information System (INIS)

    Hinterberher, F.

    1996-01-01

    The EDDA experiment is designed to provide a high precision measurement of proton-proton elastic scattering excitation functions ranging from 0.5 to 2.5 GeV of (lab) incident kinetic energy. It is an internal target experiment utilizing the proton beam of the cooler synchrotron COSY operated by KFA Juelich. The excitation functions are measured during the acceleration ramp of COSY. (author)

  19. Multiple electromagnetic excitations of relativistic projectiles

    International Nuclear Information System (INIS)

    Llope, W.J.; Braun-Munzinger, P.

    1992-01-01

    Conditions optimum for the first experimental verification of the multiplication electromagnetic excitations of nuclei in relativistic nucleus-nucleus collisions are described. The relative magnitudes of three important physical processes that might interfere with such a measurement are compared to the predicted strengths for the single and multiple electromagnetic excitations for various choices of the projectile mass and beam energy. Strategies are presented for making inferences concerning the presence of multiple excitation strength in experimental data

  20. Stimulated emission depletion following two photon excitation

    OpenAIRE

    Marsh, R. J.; Armoogum, D. A.; Bain, A. J.

    2002-01-01

    The technique of stimulated emission depletion of fluorescence (STED) from a two photon excited molecular population is demonstrated in the S, excited state of fluorescein in ethylene glycol and methanol. Two photon excitation (pump) is achieved using the partial output of a regeneratively amplified Ti:Sapphire laser in conjunction with an optical parametric amplifier whose tuneable output provides a synchronous depletion (dump) pulse. Time resolved fluorescence intensity and anisotropy measu...

  1. Nuclear wobbling-phonon excitations with alignments

    International Nuclear Information System (INIS)

    Hamamoto, I.

    2003-01-01

    Wobbling-phonon excitations, which are recently observed in 71 163 Lu 92 , are studied. The presence of alignments in nuclei makes it easier for wobbling excitations to appear at lower angular momenta of the yrast spectra. A family of rotational bands with wobbling excitations, which have nearly the same nuclear intrinsic structure, have been pinned down by observing specific electromagnetic decay properties between them. The triaxiality parameter γ = +20 deg. is obtained for the nuclear shape from measured E2 transition probabilities

  2. New mode of magnetic excitation in praseodymium

    DEFF Research Database (Denmark)

    Clausen, K.N.; McEwen, K.A.; Jensen, J.

    1994-01-01

    A novel propagating mode of magnetic excitation has been observed in Pr. It takes the form of low-energy satellites to the crystal-field excitations on both the hexagonal and cubic sites which are very broad at long wavelengths, rise in energy and rapidly narrow with increasing q, and disappear...... beyond the point at which the two excitations would cross. The broadening may be abruptly quenched by a magnetic field. The satellite excitations are believed to be associated with the dynamics of the conduction electrons....

  3. Stabilization of nonlinear excitations by disorder

    DEFF Research Database (Denmark)

    Christiansen, Peter Leth; Gaididei, Yuri Borisovich; Johansson, M.

    1998-01-01

    Using analytical and numerical techniques we analyze the static and dynamical properties of solitonlike excitations in the presence of parametric disorder in the one-dimensional nonlinear Schrodinger equation with a homogeneous power nonlinearity. Both the continuum and the discrete problem...... are investigated. We find that otherwise unstable excitations can be stabilized by the presence of disorder in the continuum problem. For the very narrow excitations of the discrete problem we find that the disorder has no effect on the averaged behavior. Finally, we show that the disorder can be applied to induce...... a high degree of controllability of the spatial extent of the stable excitations in the continuum system....

  4. Numerical simulation of the cavitation's hydrodynamic excitement

    International Nuclear Information System (INIS)

    Hassis, H.; Dueymes, E.; Lauro, J.F.

    1993-01-01

    First, we study the motion, the velocity, the phases plane and the acoustic sources associated to a spherical bubble in a compressible or incompressible medium. The bubble can be excited by periodic or random excitements. We study the parameters which influence their behaviour: periodicity or not of motion, implosion and explosion or oscillation of bubble. We take into account this behaviour in a model of cavitation: it is a numerical simulation using population of bubbles which are with positions (in the cavitation volume) and sizes are random. These bubbles are excited by a random excitement: a model of turbulent flow or implosion and explosion of bubble. (author)

  5. Excited-state density functional theory

    International Nuclear Information System (INIS)

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

    2012-01-01

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

  6. The mechanisms of Excited states in enzymes

    DEFF Research Database (Denmark)

    Petersen, Frederic Nicolas Rønne; Bohr, Henrik

    2010-01-01

    Enzyme catalysis is studied on the basis of excited state processes, which are of electronic, vibrational and thermal nature. The ways of achieving the excited state, such as photo-absorption and ligand binding, are discussed and exemplified by various cases of enzymes.......Enzyme catalysis is studied on the basis of excited state processes, which are of electronic, vibrational and thermal nature. The ways of achieving the excited state, such as photo-absorption and ligand binding, are discussed and exemplified by various cases of enzymes....

  7. Coulomb and nuclear excitations of narrow resonances in 17Ne

    Directory of Open Access Journals (Sweden)

    J. Marganiec

    2016-08-01

    Full Text Available New experimental data for dissociation of relativistic 17Ne projectiles incident on targets of lead, carbon, and polyethylene targets at GSI are presented. Special attention is paid to the excitation and decay of narrow resonant states in 17Ne. Distributions of internal energy in the O15+p+p three-body system have been determined together with angular and partial-energy correlations between the decay products in different energy regions. The analysis was done using existing experimental data on 17Ne and its mirror nucleus 17N. The isobaric multiplet mass equation is used for assignment of observed resonances and their spins and parities. A combination of data from the heavy and light targets yielded cross sections and transition probabilities for the Coulomb excitations of the narrow resonant states. The resulting transition probabilities provide information relevant for a better understanding of the 17Ne structure.

  8. Analysis of piping system response to seismic excitations

    International Nuclear Information System (INIS)

    Wang, C.Y.

    1987-01-01

    This paper describes a numerical algorithm for analyzing piping system response to seismic excitations. The numerical model of the piping considers hoop, flexural, axial, and torsional modes of deformation. Hoop modes generated from internal hydrodynamic loading are superimposed on the bending and twisting modes by two extra degrees of freedom. A time-history analysis technique using the implicit temporal integration scheme is addressed. The time integrator uses a predictor-corrector successive iterative scheme which satisfies the equation of motion. Both geometrical and material nonlinearities are considered. Multiple support excitations, fluid effect, piping insulation, and material dampings can be included in the analysis. Two problems are presented to illustrate the method. The results are discussed in detail

  9. Concentrations of the acute phase reactants high-sensitive C-reactive protein and YKL-40 and of interleukin-6 before and after treatment in patients with acromegaly and growth hormone deficiency

    DEFF Research Database (Denmark)

    Andreassen, Mikkel; Vestergaard, Henrik; Kristensen, Lars Østergaard

    2007-01-01

    Acromegaly is accompanied by increased cardiovascular mortality and a cluster of proatherogenic risk factors. In the general population, ischaemic heart disease (IHD) is associated with elevated levels of inflammatory markers. The acute phase reactant (APR) C-reactive protein (CRP) has been...... reported to be reduced in acromegaly and increase after treatment, suggesting that excess of GH/IGF-I could have anti-inflammatory effects. This is in accordance with results obtained in patients with growth hormone deficiency (GHD), where increased levels of CRP have been reported....

  10. Studies on the substrate mediated vibrational excitation of CO/Si(100) by means of SFG spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Han, Xu; Lass, Kristian; Balgar, Thorsten; Hasselbrink, Eckart [Universitaet Duisburg-Essen, Fachbereich Chemie, 45117 Essen (Germany)

    2009-07-01

    Vibrational excitations of adsorbates play an important role in chemical reaction dynamics. In the past decade CO on solid surfaces was chosen as adequate model system for studying vibrational relaxation dynamics. Our work is focused on the energy dissipation of vibrationally excited CO adsorbed on a silicon surface by means of IR/Vis sum frequency generation (SFG) spectroscopy. Here we present studies on substrate mediated excitation of vibrational modes of CO on Si(100) induced by UV radiation. We suppose the observation of highly excited internal stretch vibrations of CO caused by hot electrons generated within the silicon substrate.

  11. LS1: exciting times ahead

    CERN Multimedia

    Caroline Duc

    2013-01-01

    As the first and last proton-lead run of 2013 draws to a close, the extensive upgrade and maintenance programme of the LHC's first long shutdown (LS1) is about to get under way.   The LHC has provided physicists with a huge quantity of data to analyse since the first physics run in 2009. Now it's time for the machine, along with CERN's other accelerators, to get a facelift. LS1 will start on 13 February 2013, but this doesn’t mean that life at the Laboratory will be any less rich and exciting. Although there will be no collisions for a period of almost two years, the whole CERN site will be a hive of activity, with large-scale work under way to modernise the infrastructure and prepare the LHC for operation at higher energy. "A whole series of renovation work will be carried out around the LHC during LS1,” explains Simon Baird, deputy head of the EN Department. "The key driver is of course the consolidation of the 10,170 high-curren...

  12. Transverse excitations of 19F

    International Nuclear Information System (INIS)

    Donne, A.J.H.

    1985-01-01

    In this thesis aspects of the structure of the nucleus 19 F are discussed as a result of transverse electron-scattering experiments, with emphasis on the ground state. The magnetization distribution of this state has been obtained from the measurement of electrons scattered from 19 F at backward angles. An introduction to the electron-scattering formalism is presented briefly together with the interpretation of electron-scattering results in terms of the nuclear shell model. The experimental apparatus for the measurement of electron scattering through an angle of 180 0 is described. This instrumentation has been installed in the low-energy facility (LEF) at NIKHEF-K. Simultaneously with the study of the magnetic ground state distribution of 19 F, also excited states of this nucleus up to an energy of 4.4 MeV have been investigated, mainly from data obtained in the EMIN station. Also for these states, the shell-model calculations have been the guide to determine their structure. (Auth.)

  13. Nuclear excitations and reaction mechanisms

    International Nuclear Information System (INIS)

    Fallieros, S.; Levin, F.S.

    1990-01-01

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

  14. Excited-state imaging of cold atoms

    NARCIS (Netherlands)

    Sheludko, D.V.; Bell, S.C.; Vredenbregt, E.J.D.; Scholten, R.E.; Deshmukh, P.C.; Chakraborty, P.; Williams, J.F.

    2007-01-01

    We have investigated state-selective diffraction contrast imaging (DCI) of cold 85Rb atoms in the first excited (52P3/2) state. Excited-state DCI requires knowledge of the complex refractive index of the atom cloud, which was calculated numerically using a semi-classical model. The Autler-Townes

  15. Mean excitation energies for molecular ions

    DEFF Research Database (Denmark)

    Jensen, Phillip W.K.; Sauer, Stephan P.A.; Oddershede, Jens

    2017-01-01

    The essential material constant that determines the bulk of the stopping power of high energy projectiles, the mean excitation energy, is calculated for a range of smaller molecular ions using the RPA method. It is demonstrated that the mean excitation energy of both molecules and atoms increase...

  16. Spectrochemical analysis using laser plasma excitation

    International Nuclear Information System (INIS)

    Radziemski, L.J.

    1989-01-01

    This paper reports on analyses of gases, liquids, particles, and surfaces in which laser plasma is used to vaporize and excite a material. The authors present a discussion of the interaction between laser radiation and a solid and some recent analytical results using laser plasma excitation on metals. The use of laser plasmas as an ablation source is also discussed

  17. Excitations of Neodymium Ions in Praseodymium

    DEFF Research Database (Denmark)

    Wulff, M.; Jensen, J.; Mackintosh, A.R.

    1983-01-01

    The excitations of Nd ions dissolved in Pr have been studied by inelastic neutron scattering. A crystal-field level at about 1.2 meV interferes strongly with the host excitations. In the antiferromagnetic phase, another level is observed about 0.5 meV above the ground-state, which is split...

  18. S-parameters for weakly excited slots

    DEFF Research Database (Denmark)

    Albertsen, Niels Christian

    1999-01-01

    A simple approach to account for parasitic effects in weakly excited slots cut in the broad wall of a rectangular waveguide is proposed......A simple approach to account for parasitic effects in weakly excited slots cut in the broad wall of a rectangular waveguide is proposed...

  19. Multimode optical fibers: steady state mode exciter.

    Science.gov (United States)

    Ikeda, M; Sugimura, A; Ikegami, T

    1976-09-01

    The steady state mode power distribution of the multimode graded index fiber was measured. A simple and effective steady state mode exciter was fabricated by an etching technique. Its insertion loss was 0.5 dB for an injection laser. Deviation in transmission characteristics of multimode graded index fibers can be avoided by using the steady state mode exciter.

  20. Evolution of Excited Convective Cells in Plasmas

    DEFF Research Database (Denmark)

    Pécseli, Hans; Juul Rasmussen, Jens; Sugai, H.

    1984-01-01

    Convective cells are excited externally in a fully ionized magnetized plasma and their space-time evolution is investigated by two-dimensional potential measurements. A positive cell is excited externally by control of the end losses in the 'scrape off' layer of a plasma column produced by surface...

  1. Total cross section of highly excited strings

    International Nuclear Information System (INIS)

    Lizzi, F.; Senda, I.

    1990-01-01

    The unpolarized total cross section for the joining of two highly excited strings is calculated. The calculation is performed by taking the average overall states in the given excitation levels of the initial strings. We find that the total cross section grows with the energy and momentum of the initial states. (author). 8 refs, 1 fig

  2. Using excitation patterns to predict auditory masking

    NARCIS (Netherlands)

    Heijden, van der M.L.; Kohlrausch, A.G.

    1992-01-01

    We investigated how well auditory masking can be predicted from excitation patterns. For this purpose, a quantitative model proposed by Moore and Glasberg (1987) and Glasberg and Moore (1990) was used to calculate excitation patterns evoked by stationary sounds. We performed simulations of a number

  3. Isotope separation using vibrationally excited molecules

    International Nuclear Information System (INIS)

    Woodroffe, J.A.; Keck, J.C.

    1979-01-01

    Vibrational excitation of molecules having components of a selected isotope type is used to produce a conversion from vibrational to translational excitation of the molecules by collision with the molecules of a heavy carrier gas. The resulting difference in translaton between the molecules of the selected isotope type and all other molecules of the same compound permits their separate collection. When applied to uranium enrichment, a subsonic cryogenic flow of molecules of uranium hexafluoride in combination with an argon carrier gas is directed through a cooled chamber that is illuminated by laser radiaton tuned to vibrationally excite the uranium hexafluoride molecules of a specific uranium isotope. The excited molecules collide with carrier gas molecules, causing a conversion of the excitation energy into a translation of the excited molecule, which results in a higher thermal energy or diffusivity than that of the other uranium hexafluoride molecules. The flowing molecules including the excited molecules directly enter a set of cryogenically cooled channels. The higher thermal velocity of the excited molecules increases the probability of their striking a collector surface. The molecules which strike this surface immediately condense. After a predetermined thickness of molecules is collected on the surface, the flow of uranium hexafluoride is interrupted and the chamber heated to the point of vaporization of the collected hexafluoride, permitting its removal. (LL)

  4. Selective Coherent Excitation of Charged Density Waves

    NARCIS (Netherlands)

    Tsvetkov, A.A.; Sagar, D.M.; Loosdrecht, P.H.M. van; Marel, D. van der

    2003-01-01

    Real time femtosecond pump-probe spectroscopy is used to study collective and single particle excitations in the charge density wave state of the quasi-1D metal, blue bronze. Along with the previously observed collective amplitudon excitation, the spectra show several additional coherent features.

  5. Coulomb excitation of radioactive {sup 79}Pb

    Energy Technology Data Exchange (ETDEWEB)

    Lister, C.J.; Blumenthal, D.; Davids, C.N. [and others

    1995-08-01

    The technical challenges expected in experiments with radioactive beams can already be explored by using ions produced in primary reactions. In addition, the re-excitation of these ions by Coulomb excitation allows a sensitive search for collective states that are well above the yrast line. We are building an experiment to study Coulomb excitation of radioactive ions which are separated from beam particles by the Fragment Mass Analyzer. An array of gamma detectors will be mounted at the focal plane to measure the gamma radiation following re-excitation. Five Compton-suppressed Ge detectors and five planar LEPS detectors will be used. The optimum experiment of this type appears to be the study of {sup 79}Rb following the {sup 24}Mg ({sup 58}Ni,3p) reaction. We calculate that about 5 x 10{sup 5} {sup 79}Rb nuclei/second will reach the excitation foil. This rubidium isotope was selected for study as it is strongly produced and is highly deformed, so easily re-excited. The use of a {sup 58}Ni re-excitation foil offers the best yields. After re-excitation the ions will be subsequently transported into a shielded beamdump to prevent the accumulation of activity.

  6. Production of Excited Neutrinos at the LHC

    CERN Document Server

    Belyaev, A; Mehdiyev, R

    2005-01-01

    We study the potential of the CERN LHC in the search for the single production of excited neutrino through gauge interactions. Subsequent decays of excited neutrino via gauge interactions are examined. The mass range accessible with the ATLAS detector is obtained.

  7. A large electrically excited synchronous generator

    DEFF Research Database (Denmark)

    2014-01-01

    This invention relates to a large electrically excited synchronous generator (100), comprising a stator (101), and a rotor or rotor coreback (102) comprising an excitation coil (103) generating a magnetic field during use, wherein the rotor or rotor coreback (102) further comprises a plurality...... adjacent neighbouring poles. In this way, a large electrically excited synchronous generator (EESG) is provided that readily enables a relatively large number of poles, compared to a traditional EESG, since the excitation coil in this design provides MMF for all the poles, whereas in a traditional EESG...... each pole needs its own excitation coil, which limits the number of poles as each coil will take up too much space between the poles....

  8. Excitation methods for energy dispersive analysis

    International Nuclear Information System (INIS)

    Jaklevic, J.M.

    1976-01-01

    The rapid development in recent years of energy dispersive x-ray fluorescence analysis has been based primarily on improvements in semiconductor detector x-ray spectrometers. However, the whole analysis system performance is critically dependent on the availability of optimum methods of excitation for the characteristic x rays in specimens. A number of analysis facilities based on various methods of excitation have been developed over the past few years. A discussion is given of the features of various excitation methods including charged particles, monochromatic photons, and broad-energy band photons. The effects of the excitation method on background and sensitivity are discussed from both theoretical and experimental viewpoints. Recent developments such as pulsed excitation and polarized photons are also discussed

  9. Molecular excited states from the SCAN functional

    Science.gov (United States)

    Tozer, David J.; Peach, Michael J. G.

    2018-06-01

    The performance of the strongly constrained and appropriately normed (SCAN) meta-generalised gradient approximation exchange-correlation functional is investigated for the calculation of time-dependent density-functional theory molecular excitation energies of local, charge-transfer and Rydberg character, together with the excited ? potential energy curve in H2. The SCAN results frequently resemble those obtained using a global hybrid functional, with either a standard or increased fraction of exact orbital exchange. For local excitations, SCAN can exhibit significant triplet instability problems, resulting in imaginary triplet excitation energies for a number of cases. The Tamm-Dancoff approximation offers a simple approach to improve the situation, but the excitation energies are still significantly underestimated. Understanding the origin of these (near)-triplet instabilities may provide useful insight into future functional development.

  10. Vibrational and rotational excitation effects of the N(2D) + D2(X1Σg +) → ND(X3Σ+) + D(2S) reaction

    Science.gov (United States)

    Zhu, Ziliang; Wang, Haijie; Wang, Xiquan; Shi, Yanying

    2018-05-01

    The effects of the rovibrational excitation of reactants in the N(2D) + D2(X1Σg+) → ND(X3Σ+) + D(2S) reaction are calculated in a collision energy range from the threshold to 1.0 eV using the time-dependent wave packet approach and a second-order split operator. The reaction probability, integral cross-section, differential cross-section and rate constant of the title reaction are calculated. The integral cross-section and rate constant of the initial states v = 0, j = 0, 1, are in good agreement with experimental data available in the literature. The rotational excitation of the D2 molecule has little effect on reaction probability, integral cross-section and the rate constant, but it increased the sideways and forward scattering signals. The vibrational excitation of the D2 molecule reduced the threshold and broke up the forward-backward symmetry of the differential cross-section; it also increased the forward scattering signals. This may be because the vibrational excitation of the D2 molecule reduced the lifetime of the intermediate complex.

  11. Highly efficient quenching of tris(2,2'-bipyridyl)ruthenium(II) electrochemiluminescence by ozone using formaldehyde, methylglyoxal, and glyoxalate as co-reactants and its application to ozone sensing.

    Science.gov (United States)

    Gao, Ying; Liu, Xiaoyun; Qi, Wenjing; Gao, Wenyue; Li, Yunhui; Xu, Guobao

    2015-06-21

    Most electrochemiluminescence (ECL) systems require high concentrations of quencher to totally quench ECL. In this study, we found that ozone can quench tris(2,2'-bipyridyl)ruthenium(II) ECL using formaldehyde, methylglyoxal, or glyoxalate as co-reactants at a glassy carbon electrode with remarkable efficiencies even when the concentration of ozone is merely 0.25% of that of the co-reactant. The strongest quenching is observed with the tris(2,2'-bipyridyl)ruthenium(II)/formaldehyde ECL system. The tris(2,2'-bipyridyl)ruthenium(II)/formaldehyde ECL intensities decrease linearly with the ozone concentration over the range of 0.025-25 μM (r = 0.9947) with a limit of detection of 8 nM. The method is more sensitive and faster than most methods. It shows high selectivity in the presence of other ROS or oxidants and some metal ions, such as H2O2, ClO(-), Mg(2+), Ni(2+), etc. The method exhibits high recoveries for the detection of ozone in a ventilated photocopy room.

  12. Photocatalytic Conversion of Carbon Dioxide Using Zn–Cu–Ga Layered Double Hydroxides Assembled with Cu Phthalocyanine: Cu in Contact with Gaseous Reactant is Needed for Methanol Generation

    Directory of Open Access Journals (Sweden)

    Kawamura Shogo

    2015-09-01

    Full Text Available Photocatalytic conversion of CO2 into fuels is an attractive option in terms of both reducing the increased concentration of atmospheric CO2 as well as generating renewable hydrocarbon fuels. It is necessary to investigate good catalysts for CO2 conversion and to clarify the mechanism irradiated by natural light. Layered Double Hydroxides (LDH have been attracting attention for CO2 photoreduction with the expectation of sorption capacity for CO2 in the layered space and tunable semiconductor properties as a result of the choice of metal cations. This study first clarifies the effects of Cu doping to LDH comprising Zn and Al or Ga. Cu could be incorporated in the cationic layers of LDH as divalent metal cations and/or interlayer anions as Cu(OH42−. The formation rates of methanol and CO were optimized for [Zn1.5Cu1.5Ga(OH8]+2Cu(OH42−·mH2O at a total rate of 560 nmol h−1 gcat−1 irradiated by UV–visible light. Cu phthalocyanine tetrasulfonate hydrate (CuPcTs4− and silver were effective as promoters of LDH for CO2 photoreduction. Especially, the total formation rate using CuPcTs-[Zn3Ga(OH8]+2CO32−·mH2O irradiated by visible light was 73% of that irradiated by UV–visible light. The promotion was based on HOMO–LUMO excitation of CuPcTs4− by visible light. The LUMO was distributed on N atoms of pyrrole rings bound to central Cu2+ ions. The photogenerated electrons diffused to the Cu site would photoreduce CO2 progressively in a similar way to inlayer and interlayer Cu sites in the LDH in this study.

  13. Effects of periodontal afferent inputs on corticomotor excitability in humans

    DEFF Research Database (Denmark)

    Zhang, Y; Boudreau, S; Wang, M

    2010-01-01

    for the first dorsal interosseous (FDI) as an internal control. Burning pain intensity and mechanical sensitivity ratings to a von Frey filament applied to the application site were recorded on an electronic visual analogue scale (VAS). All subjects reported a decreased mechanical sensitivity (anova: P = 0......-injection for the LA (anovas: P > 0.22) or capsaicin (anovas: P > 0.16) sessions. These findings suggest that a transient loss or perturbation in periodontal afferent input to the brain from a single incisor is insufficient to cause changes in corticomotor excitability of the face MI, as measured by TMS in humans....

  14. Electron affinity and excited states of methylglyoxal

    Science.gov (United States)

    Dauletyarov, Yerbolat; Dixon, Andrew R.; Wallace, Adam A.; Sanov, Andrei

    2017-07-01

    Using photoelectron imaging spectroscopy, we characterized the anion of methylglyoxal (X2A″ electronic state) and three lowest electronic states of the neutral methylglyoxal molecule: the closed-shell singlet ground state (X1A'), the lowest triplet state (a3A″), and the open-shell singlet state (A1A″). The adiabatic electron affinity (EA) of the ground state, EA(X1A') = 0.87(1) eV, spectroscopically determined for the first time, compares to 1.10(2) eV for unsubstituted glyoxal. The EAs (adiabatic attachment energies) of two excited states of methylglyoxal were also determined: EA(a3A″) = 3.27(2) eV and EA(A1A″) = 3.614(9) eV. The photodetachment of the anion to each of these two states produces the neutral species near the respective structural equilibria; hence, the a3A″ ← X2A″ and A1A″ ← X2A″ photodetachment transitions are dominated by intense peaks at their respective origins. The lowest-energy photodetachment transition, on the other hand, involves significant geometry relaxation in the X1A' state, which corresponds to a 60° internal rotation of the methyl group, compared to the anion structure. Accordingly, the X1A' ← X2A″ transition is characterized as a broad, congested band, whose vertical detachment energy, VDE = 1.20(4) eV, significantly exceeds the adiabatic EA. The experimental results are in excellent agreement with the ab initio predictions using several equation-of-motion methodologies, combined with coupled-cluster theory.

  15. Seismic excitation by space shuttles

    Science.gov (United States)

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

    1992-01-01

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

  16. Reaction of H2 with O2 in Excited Electronic States: Reaction Pathways and Rate Constants.

    Science.gov (United States)

    Pelevkin, Alexey V; Loukhovitski, Boris I; Sharipov, Alexander S

    2017-12-21

    Comprehensive quantum chemical analysis with the use of the multireference state-averaged complete active space self-consistent field approach was carried out to study the reactions of H 2 with O 2 in a 1 Δ g , b 1 Σ g + , c 1 Σ u - , and A' 3 Δ u electronically excited states. The energetically favorable reaction pathways and possible intersystem crossings have been revealed. The energy barriers were refined employing the extended multiconfiguration quasi-degenerate second-order perturbation theory. It has been shown that the interaction of O 2 (a 1 Δ g ) and O 2 (A' 3 Δ u ) with H 2 occurs through the H-abstraction process with relatively low activation barriers that resulted in the formation of the HO 2 molecule in A″ and A' electronic states, respectively. Meanwhile, molecular oxygen in singlet sigma states (b 1 Σ g + and c 1 Σ u - ) was proved to be nonreactive with respect to the molecular hydrogen. Appropriate rate constants for revealed reaction and quenching channels have been estimated using variational transition-state theory including corrections for the tunneling effect, possible nonadiabatic transitions, and anharmonicity of vibrations for transition states and reactants. It was demonstrated that the calculated reaction rate constant for the H 2 + O 2 (a 1 Δ g ) process is in reasonable agreement with known experimental data. The Arrhenius approximations for these processes have been proposed for the temperature range T = 300-3000 K.

  17. Experimental determination of electron shock excitation cross sections for a singly charged gadolinium ion

    International Nuclear Information System (INIS)

    Smirnov, Yu.M.

    1995-01-01

    The trends observed in the processes of excitation with simultaneous ionization have received little study. This is particularly so for rare-earth elements having electron shells of complex structure and optical spectra very rich in lines. Among the basic factors responsible for such a situation, we should mention two: the difficulty presented by theoretical analysis of the processes discussed and the absence of factual information about the excitation cross sections with simultaneous ionization for the majority of rare-earth elements. The aim of the present work is to investigate the excitation of a singly charged gadolinium ion in the collisions of monokinetic electrons with gadolinium atoms. Up to the present time, only the excitation cross sections of a gadolinium atom have been measured, where investigation of the electron shock excitation of gadolinium atoms in their free state is associated with overcoming large experimental difficulties. About 160 crosss sections for the excitation of a singly charged gadolinium ion were measured and for a third of the cross sections; the energy dependences were recorded for the change in energy of the elecrons from the excitation threshold up to 200 eV. Included are tables of the wavelength, transistion, internal quantum number, the energy of the lowere and upper levels, and the values of cross sections for the charged gadolinium ion. Diagrams of the transistion energy states of Gd (II) and spectroscopy are presented and explained

  18. Controlling flexible rotor vibrations using parametric excitation

    Energy Technology Data Exchange (ETDEWEB)

    Atepor, L, E-mail: katepor@yahoo.co [Department of Mechanical Engineering, University of Glasgow, G12 8QQ (United Kingdom)

    2009-08-01

    This paper presents both theoretical and experimental studies of an active vibration controller for vibration in a flexible rotor system. The paper shows that the vibration amplitude can be modified by introducing an axial parametric excitation. The perturbation method of multiple scales is used to solve the equations of motion. The steady-state responses, with and without the parametric excitation terms, is investigated. An experimental test machine uses a piezoelectric exciter mounted on the end of the shaft. The results show a reduction in the rotor response amplitude under principal parametric resonance, and some good correlation between theory and experiment.

  19. Hyperon excitation in nuclear coulomb field

    International Nuclear Information System (INIS)

    Vanyashin, A.V.; Nikitin, Yu.P.; Shan'gin, A.A.

    1981-01-01

    A possibility is studied to measure radiative decay partial widths from the 3/2 + decuplet hyperon resonances by means of the Coulomb excitation method of the octet hyperons. The expected contributions from the strong and electromagnetic interactions in the coherence range to the hyperon excitation cross sections on heavy nuclei and on the 4 He nucleus are estimated. The particle angular distributions in the reactions Σ-+A→Σ-(1385)+A and Λ+A→Σ 0 (1385)+A are analysed in order to determine the energy range where the background conditions are the most favorable to extract the electromagnetic mechanism of the hyperon excitation [ru

  20. Excited-state molecular photoionization dynamics

    International Nuclear Information System (INIS)

    Pratt, S.T.

    1995-01-01

    This review presents a survey of work using resonance-enhanced multiphoton ionization and double-resonance techniques to study excited-state photoionization dynamics in molecules. These techniques routinely provide detail and precision that are difficult to achieve in single-photon ionization from the ground state. The review not only emphasizes new aspects of photoionization revealed in the excited-state experiments but also shows how the excited-state techniques can provide textbook illustrations of some fundamental mechanisms in molecular photoionization dynamics. Most of the examples are confined to diatomic molecules. (author)

  1. Surface and bulk excitations in condensed matter

    International Nuclear Information System (INIS)

    Ritchie, R.H.

    1988-01-01

    In this lecture collective and single-particle electron excitations of solids will be discussed with emphasis on the properties of metallic and semiconducting materials. However, some of the general properties of long-wavelength collective modes to be discussed are valid for insulators as well, and some considerations apply to nuclear excitations such as optical or acoustical phonons, dipolar plasmons, etc. The concept of elementary excitations in solids, pioneered by Bohm and Pines almost 4 decades ago, has proved to be extremely useful in understanding the properties of systems of many particles, especially in respect to the response to the action of external probes. 32 refs., 12 figs

  2. Two-photon excitation of argon

    International Nuclear Information System (INIS)

    Pindzola, P.S.; Payne, M.C.

    1982-01-01

    The authors calculate two photon excitation parameters for various excited states of argon assuming the absorption of near resonance broad-bandwidth laser radiation. Results are given for the case of two photons absorbed for the same laser beam as well as the case of absorbing photons of different frequency from each of two laser beams. The authors use multiconfiguration Hartree-Fock wave functions to evaluate the second-order sums over matrix elements. Various experimental laser schemes are suggested for the efficient excitation and subsequent ionization of argon

  3. Recent experiments involving highly excited atoms

    International Nuclear Information System (INIS)

    Latimer, C.J.

    1979-01-01

    Very large and fragile atoms may be produced by exciting normal atoms with light or by collisions with other atomic particles. Atoms as large as 10 -6 m are now routinely produced in the laboratory and their properties studied. In this review some of the simpler experimental methods available for the production and detection of such atoms are described including tunable dye laser-excitation and field ionization. A few recent experiments which illustrate the collision properties and the effects of electric and and magnetic fields are also described. The relevance of highly excited atoms in other areas of research including radioastronomy and isotope separation are discussed. (author)

  4. Geophysical excitation of the chandler wobble revisited

    OpenAIRE

    A. Brzezinski; Henryk Dobslaw; Robert Dill; Maik Thomas

    2012-01-01

    The 14-month Chandler wobble is a free motion of the pole excited by geophysical processes. Several recent studies demonstrated that the combination of atmospheric and oceanic excitations contains enough power at the Chandler frequency and is significantly coherent with the observed free wobble. This paper is an extension of earlier studies by Brzeziński and Nastula (Adv Space Res 30:195–200, 2002), Brzeziński et al. (Oceanic excitation of the Chandler wobble using a 50-year time series of oc...

  5. Symmetry characterization of electrons and lattice excitations

    Directory of Open Access Journals (Sweden)

    Schober H.

    2012-03-01

    Full Text Available Symmetry concerns all aspects of a physical system from the electronic orbitals to structural and magnetic excitations. In this article we will try to elaborate the fundamental connection between symmetry and excitations. As excitations are manyfold in physical systems it is impossible to treat them exhaustively. We thus concentrate on the two topics of Bloch electrons and phonons. These two examples are complementary in the sense that Bloch electrons describe single particles in an external periodic potential while phonons exemplify a decoupled system of interacting particles. The way we develop the argument gives as by-product a short account of molecular orbitals and molecular vibrations.

  6. Particle hole excitations coupled to complex states in heavy-ion collisions

    International Nuclear Information System (INIS)

    Jolos, R.V.; Schmidt, R.

    1982-01-01

    The excitation of uncorrelated 1p-1h states in one nucleus due to the action of the time-dependent mean field of the other nucleus was studied earlier. No statistical assumptions or average procedures were made. Such a mechanism can be responsible for an appreciable excitation of the two nuclei during the short approach phase of the reaction (E* approximately> 100 MeV). The reversibility of the equations of motion leads to a deexcitation of the initially stored excitation energy into that of the relative motion for later times. This feedback behaviour of the internal excitation energy which results in particular to the deexcitation of high energetic 1p-1h pairs is probably not realistic due to the coupling of this states to more complex states with high density. It is studied the influence of this coupling due to the residual interaction between the nucleons on the dynamics of two colliding heavy ions

  7. The DSS-14 C-band exciter

    Science.gov (United States)

    Rowan, D. R.

    1989-01-01

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

  8. Excitation of giant resonances through inelastic scattering

    International Nuclear Information System (INIS)

    Kailas, S.

    1981-01-01

    In the last few years, exciting developments have taken place in the study of giant resonances (GR). In addition to the already well known gjant dipole resonance (GDR), the presence of at least two more new GRs viz. giant quadrupole resonance (GQR) and giant monopole resonance (GMR) has been experimentally established. The systematics covering these GRs is found to be consistent with the theoretical expectation. Though the existence of higher multipoles has been predjcted by theory, so far only some of these have been found to be excited experimentally. Various probe particles - electrons, protons (polarized and unpolarized), light and heavy ions and pions - at different bombarding energies have been used to excite the GR region, primarily through the inelastic scattering process. Detailed experiments, looking at the decay modes of GR region, have also been performed. These studies have contributed significantly to a better understanding of the phenomenon of nuclear collective excitation. In this report, the current status of 'GR' research is reviewed. (author)

  9. Dark excitations in monolayer transition metal dichalcogenides

    DEFF Research Database (Denmark)

    Deilmann, Thorsten; Thygesen, Kristian Sommer

    2017-01-01

    Monolayers of transition metal dichalcogenides (TMDCs) possess unique optoelectronic properties, including strongly bound excitons and trions. To date, most studies have focused on optically active excitations, but recent experiments have highlighted the existence of dark states, which are equally...

  10. Non-equilibrium entropy in excited nuclei

    International Nuclear Information System (INIS)

    Betak, E.

    1991-06-01

    The time-dependent behaviour of entropy in excited nuclei is investigated. In distinction to recent claims, it is shown that no self-organization is involved in pre-equilibrium nuclear reactions. (author). 9 refs.; 4 figs

  11. Wideband MEMS Resonator Using Multifrequency Excitation

    KAUST Repository

    Jaber, Nizar; Ramini, Abdallah; Al Hennawi, Qais M.; Younis, Mohammad I.

    2016-01-01

    We demonstrate the excitation of combination resonances of additive and subtractive types and their exploitations to realize a large bandwidth micro-machined resonator of large amplitude even at higher harmonic modes of vibrations. The investigation is conducted on a Microelectromechanical systems (MEMS) clamped-clamped microbeam fabricated using polyimide as a structural layer coated with nickel from top and chromium and gold layers from bottom. The microbeam is excited by a two-source harmonic excitation, where the first frequency source is swept around the targeted resonance (first or third mode of vibration) while the second source frequency is kept fixed. We report for the first time a large bandwidth and large amplitude response near the higher order modes of vibration. Also, we show that by properly tuning the frequency and amplitude of the excitation force, the frequency bandwidth of the resonator is controlled.

  12. Regulation of fields excited by permanent magnets

    International Nuclear Information System (INIS)

    Savchenko, I.S.

    1989-01-01

    Two methods of fast regulation of fields excited by permanent magnets in salient-pole electron-optical lenses are described: 1)the hybrid method realized using the additional electromagnet introduced to a magnetic chain sequentially its field being composed or substracted with magnetosolid exciter field; 2)the method with saturation of a part of a magnetic circuit, with saturation being achievable at the begining or in the end of a regulation cycle. In the second method it is proposed to direct orthogonally the main flux excited by permanent magnets and the flux in the saturated part of the magnetic circuit excited using an electromagnet. It is shown that the second method allows one to reduce the required ampere-coils by more than an order as compared to the first method at one and the same regulation range and other equal conditions. The frequency of field regulation in the experimental mock-up was 10 kHz. 3 refs.; 2 figs

  13. Dissociative Excitation of Thymine by Electron Impact

    Science.gov (United States)

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

    2014-05-01

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

  14. Optical studies of multiply excited states

    International Nuclear Information System (INIS)

    Mannervik, S.

    1989-01-01

    Optical studies of multiply-excited states are reviewed with emphasis on emission spectroscopy. From optical measurements, properties such as excitation energies, lifetimes and autoionization widths can be determined with high accuracy, which constitutes a challenge for modern computational methods. This article mainly covers work on two-, three- and four-electron systems, but also sodium-like quartet systems. Furthermore, some comments are given on bound multiply-excited states in negative ions. Fine structure effects on transition wavelengths and lifetimes (autoionization) are discussed. In particular, the most recent experimental and theoretical studies of multiply-excited states are covered. Some remaining problems, which require further attention, are discussed in more detail. (orig.) With 228 refs

  15. Wideband MEMS Resonator Using Multifrequency Excitation

    KAUST Repository

    Jaber, Nizar

    2016-03-09

    We demonstrate the excitation of combination resonances of additive and subtractive types and their exploitations to realize a large bandwidth micro-machined resonator of large amplitude even at higher harmonic modes of vibrations. The investigation is conducted on a Microelectromechanical systems (MEMS) clamped-clamped microbeam fabricated using polyimide as a structural layer coated with nickel from top and chromium and gold layers from bottom. The microbeam is excited by a two-source harmonic excitation, where the first frequency source is swept around the targeted resonance (first or third mode of vibration) while the second source frequency is kept fixed. We report for the first time a large bandwidth and large amplitude response near the higher order modes of vibration. Also, we show that by properly tuning the frequency and amplitude of the excitation force, the frequency bandwidth of the resonator is controlled.

  16. Faraday waves under time-reversed excitation.

    Science.gov (United States)

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

    2013-03-01

    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.

  17. Language identification using excitation source features

    CERN Document Server

    Rao, K Sreenivasa

    2015-01-01

    This book discusses the contribution of excitation source information in discriminating language. The authors focus on the excitation source component of speech for enhancement of language identification (LID) performance. Language specific features are extracted using two different modes: (i) Implicit processing of linear prediction (LP) residual and (ii) Explicit parameterization of linear prediction residual. The book discusses how in implicit processing approach, excitation source features are derived from LP residual, Hilbert envelope (magnitude) of LP residual and Phase of LP residual; and in explicit parameterization approach, LP residual signal is processed in spectral domain to extract the relevant language specific features. The authors further extract source features from these modes, which are combined for enhancing the performance of LID systems. The proposed excitation source features are also investigated for LID in background noisy environments. Each chapter of this book provides the motivatio...

  18. Students Excited by Stellar Discovery

    Science.gov (United States)

    2011-02-01

    In the constellation of Ophiuchus, above the disk of our Milky Way Galaxy, there lurks a stellar corpse spinning 30 times per second -- an exotic star known as a radio pulsar. This object was unknown until it was discovered last week by three high school students. These students are part of the Pulsar Search Collaboratory (PSC) project, run by the National Radio Astronomy Observatory (NRAO) in Green Bank, WV, and West Virginia University (WVU). The pulsar, which may be a rare kind of neutron star called a recycled pulsar, was discovered independently by Virginia students Alexander Snider and Casey Thompson, on January 20, and a day later by Kentucky student Hannah Mabry. "Every day, I told myself, 'I have to find a pulsar. I better find a pulsar before this class ends,'" said Mabry. When she actually made the discovery, she could barely contain her excitement. "I started screaming and jumping up and down." Thompson was similarly expressive. "After three years of searching, I hadn't found a single thing," he said, "but when I did, I threw my hands up in the air and said, 'Yes!'." Snider said, "It actually feels really neat to be the first person to ever see something like that. It's an uplifting feeling." As part of the PSC, the students analyze real data from NRAO's Robert C. Byrd Green Bank Telescope (GBT) to find pulsars. The students' teachers -- Debra Edwards of Sherando High School, Leah Lorton of James River High School, and Jennifer Carter of Rowan County Senior High School -- all introduced the PSC in their classes, and interested students formed teams to continue the work. Even before the discovery, Mabry simply enjoyed the search. "It just feels like you're actually doing something," she said. "It's a good feeling." Once the pulsar candidate was reported to NRAO, Project Director Rachel Rosen took a look and agreed with the young scientists. A followup observing session was scheduled on the GBT. Snider and Mabry traveled to West Virginia to assist in the

  19. Search for Excited Leptons at LEP

    CERN Document Server

    Achard, P.; Aguilar-Benitez, M.; Alcaraz, J.; Alemanni, G.; Allaby, J.; Aloisio, A.; Alviggi, M.G.; Anderhub, H.; Andreev, Valery P.; Anselmo, F.; Arefev, A.; Azemoon, T.; Aziz, T.; Bagnaia, P.; Bajo, A.; Baksay, G.; Baksay, L.; Baldew, S.V.; Banerjee, S.; Banerjee, Sw.; Barczyk, A.; Barillere, R.; Bartalini, P.; Basile, M.; Batalova, N.; Battiston, R.; Bay, A.; Becattini, F.; Becker, U.; Behner, F.; Bellucci, L.; Berbeco, R.; Berdugo, J.; Berges, P.; Bertucci, B.; Betev, B.L.; Biasini, M.; Biglietti, M.; Biland, A.; Blaising, J.J.; Blyth, S.C.; Bobbink, G.J.; Bohm, A.; Boldizsar, L.; Borgia, B.; Bottai, S.; Bourilkov, D.; Bourquin, M.; Braccini, S.; Branson, J.G.; Brochu, F.; Burger, J.D.; Burger, W.J.; Cai, X.D.; Capell, M.; Cara Romeo, G.; Carlino, G.; Cartacci, A.; Casaus, J.; Cavallari, F.; Cavallo, N.; Cecchi, C.; Cerrada, M.; Chamizo, M.; Chang, Y.H.; Chemarin, M.; Chen, A.; Chen, G.; Chen, G.M.; Chen, H.F.; Chen, H.S.; Chiefari, G.; Cifarelli, L.; Cindolo, F.; Clare, I.; Clare, R.; Coignet, G.; Colino, N.; Costantini, S.; de la Cruz, B.; Cucciarelli, S.; van Dalen, J.A.; de Asmundis, R.; Deglon, P.; Debreczeni, J.; Degre, A.; Dehmelt, K.; Deiters, K.; della Volpe, D.; Delmeire, E.; Denes, P.; DeNotaristefani, F.; De Salvo, A.; Diemoz, M.; Dierckxsens, M.; Dionisi, C.; Dittmar, M.; Doria, A.; Dova, M.T.; Duchesneau, D.; Duda, M.; Echenard, B.; Eline, A.; El Hage, A.; El Mamouni, H.; Engler, A.; Eppling, F.J.; Extermann, P.; Falagan, M.A.; Falciano, S.; Favara, A.; Fay, J.; Fedin, O.; Felcini, M.; Ferguson, T.; Fesefeldt, H.; Fiandrini, E.; Field, J.H.; Filthaut, F.; Fisher, P.H.; Fisher, W.; Fisk, I.; Forconi, G.; Freudenreich, K.; Furetta, C.; Galaktionov, Iouri; Ganguli, S.N.; Garcia-Abia, Pablo; Gataullin, M.; Gentile, S.; Giagu, S.; Gong, Z.F.; Grenier, Gerald Jean; Grimm, O.; Gruenewald, M.W.; Guida, M.; van Gulik, R.; Gupta, V.K.; Gurtu, A.; Gutay, L.J.; Haas, D.; Hakobyan, R.S.; Hansen, J.M.; Hatzifotiadou, D.; Hebbeker, T.; Herve, Alain; Hirschfelder, J.; Hofer, H.; Hohlmann, M.; Holzner, G.; Hou, S.R.; Hu, Y.; Jin, B.N.; Jones, Lawrence W.; de Jong, P.; Josa-Mutuberria, I.; Kafer, D.; Kaur, M.; Kienzle-Focacci, M.N.; Kim, J.K.; Kirkby, Jasper; Kittel, W.; Klimentov, A.; Konig, A.C.; Kopal, M.; Koutsenko, V.; Kraber, M.; Kraemer, R.W.; Kruger, A.; Kunin, A.; Ladron de Guevara, P.; Laktineh, I.; Landi, G.; Lebeau, M.; Lebedev, A.; Lebrun, P.; Lecomte, P.; Lecoq, P.; Le Coultre, P.; Le Goff, J.M.; Leiste, R.; Levtchenko, M.; Levtchenko, P.; Li, C.; Likhoded, S.; Lin, C.H.; Lin, W.T.; Linde, F.L.; Lista, L.; Liu, Z.A.; Lohmann, W.; Longo, E.; Lu, Y.S.; Luci, C.; Luminari, L.; Lustermann, W.; Ma, W.G.; Malgeri, L.; Malinin, A.; Mana, C.; Mans, J.; Martin, J.P.; Marzano, F.; Mazumdar, K.; McNeil, R.R.; Mele, S.; Merola, L.; Meschini, M.; Metzger, W.J.; Mihul, A.; Milcent, H.; Mirabelli, G.; Mnich, J.; Mohanty, G.B.; Muanza, G.S.; Muijs, A.J.M.; Musicar, B.; Musy, M.; Nagy, S.; Natale, S.; Napolitano, M.; Nessi-Tedaldi, F.; Newman, H.; Nisati, A.; Kluge, Hannelies; Ofierzynski, R.; Organtini, G.; Pal, I.; Palomares, C.; Paolucci, P.; Paramatti, R.; Passaleva, G.; Patricelli, S.; Paul, Thomas Cantzon; Pauluzzi, M.; Paus, C.; Pauss, F.; Pedace, M.; Pensotti, S.; Perret-Gallix, D.; Petersen, B.; Piccolo, D.; Pierella, F.; Pioppi, M.; Piroue, P.A.; Pistolesi, E.; Plyaskin, V.; Pohl, M.; Pojidaev, V.; Pothier, J.; Prokofev, D.; Quartieri, J.; Rahal-Callot, G.; Rahaman, Mohammad Azizur; Raics, P.; Raja, N.; Ramelli, R.; Rancoita, P.G.; Ranieri, R.; Raspereza, A.; Razis, P.; Ren, D.; Rescigno, M.; Reucroft, S.; Riemann, S.; Riles, Keith; Roe, B.P.; Romero, L.; Rosca, A.; Rosier-Lees, S.; Roth, Stefan; Rosenbleck, C.; Rubio, J.A.; Ruggiero, G.; Rykaczewski, H.; Sakharov, A.; Saremi, S.; Sarkar, S.; Salicio, J.; Sanchez, E.; Schafer, C.; Schegelsky, V.; Schopper, H.; Schotanus, D.J.; Sciacca, C.; Servoli, L.; Shevchenko, S.; Shivarov, N.; Shoutko, V.; Shumilov, E.; Shvorob, A.; Son, D.; Souga, C.; Spillantini, P.; Steuer, M.; Stickland, D.P.; Stoyanov, B.; Straessner, A.; Sudhakar, K.; Sultanov, G.; Sun, L.Z.; Sushkov, S.; Suter, H.; Swain, J.D.; Szillasi, Z.; Tang, X.W.; Tarjan, P.; Tauscher, L.; Taylor, L.; Tellili, B.; Teyssier, D.; Timmermans, Charles; Ting, Samuel C.C.; Ting, S.M.; Tonwar, S.C.; Toth, J.; Tully, C.; Tung, K.L.; Ulbricht, J.; Valente, E.; Van de Walle, R.T.; Vasquez, R.; Veszpremi, V.; Vesztergombi, G.; Vetlitsky, I.; Vicinanza, D.; Viertel, G.; Villa, S.; Vivargent, M.; Vlachos, S.; Vodopianov, I.; Vogel, H.; Vogt, H.; Vorobev, I.; Vorobyov, A.A.; Wadhwa, M.; Wang, Q.; Wang, X.L.; Wang, Z.M.; Weber, M.; Wienemann, P.; Wilkens, H.; Wynhoff, S.; Xia, L.; Xu, Z.Z.; Yamamoto, J.; Yang, B.Z.; Yang, C.G.; Yang, H.J.; Yang, M.; Yeh, S.C.; Zalite, A.; Zalite, Yu.; Zhang, Z.P.; Zhao, J.; Zhu, G.Y.; Zhu, R.Y.; Zhuang, H.L.; Zichichi, A.; Zimmermann, B.; Zoller, M.

    2003-01-01

    A search for charged and neutral excited leptons is performed in 217 pb-1 of data collected with the L3 detector at LEP at centre-of-mass energies up to 209 GeV. The pair- and single-production mechanisms are investigated and no signals are detected. Combining with L3 results from searches at lower centre-of-mass energies, gives improved limits on the masses and couplings of excited leptons.

  20. Microstructure ion Nuclear Spectra at High Excitation

    International Nuclear Information System (INIS)

    Ericson, T.E.O.

    1969-01-01

    The statistical microstructure of highly excited systems is illustrated by the distribution and fluctuations of levels, widths and cross-sections of nuclei both for the case of sharp resonances and the continuum case. The coexistence of simple modes of excitation with statistical effects in terms of strength functions is illustrated by isobaric analogue states. The analogy is made with similar phenomena for coherent light, is solid-state physics and high-energy physics. (author)

  1. Rearrangements in ground and excited states

    CERN Document Server

    de Mayo, Paul

    1980-01-01

    Rearrangements in Ground and Excited States, Volume 3 presents essays on the chemical generation of excited states; the cis-trans isomerization of olefins; and the photochemical rearrangements in trienes. The book also includes essays on the zimmerman rearrangements; the photochemical rearrangements of enones; the photochemical rearrangements of conjugated cyclic dienones; and the rearrangements of the benzene ring. Essays on the photo rearrangements via biradicals of simple carbonyl compounds; the photochemical rearrangements involving three-membered rings or five-membered ring heterocycles;

  2. Probability of collective excited state decay

    International Nuclear Information System (INIS)

    Manykin, Eh.A.; Ozhovan, M.I.; Poluehktov, P.P.

    1987-01-01

    Decay mechanisms of condensed excited state formed of highly excited (Rydberg) atoms are considered, i.e. stability of so-called Rydberg substance is analyzed. It is shown that Auger recombination and radiation transitions are the basic processes. The corresponding probabilities are calculated and compared. It is ascertained that the ''Rydberg substance'' possesses macroscopic lifetime (several seconds) and in a sense it is metastable

  3. Excitation mechanisms in singly ionized krypton laser

    International Nuclear Information System (INIS)

    El-Sherbini, Th.M.

    1982-01-01

    Lifetimes for the low lying 4p 4 4d and 4p 4 5s levels of singly ionized krypton laser are calculated, taking into account configuration interaction effects. The results show that some of these levels are metastable. They also suggest a two step excitation from the ground state of the ion (or the atom) to the upper 4p 4 5p laser levels involving some intermediate metastable states as a possible excitation mechanism. (author)

  4. Excited quark production at hadron colliders

    International Nuclear Information System (INIS)

    Baur, U.; Hinchliffe, I.; Zeppenfeld, D.

    1987-06-01

    Composite models generally predict the existence of excited quark and lepton states. We consider the production and experimental signatures of excited quarks Q* of spin and isospin 1/2 at hadron colliders and estimate the background for those channels which are most promising for Q* identification. Multi-TeV pp-colliders will give access to such particles with masses up to several TeV

  5. Propagation and excitation of graphene plasmon polaritons

    DEFF Research Database (Denmark)

    Zhu, Xiaolong; Yan, Wei; Jeppesen, Claus

    2013-01-01

    We theoretically investigate the propagation of graphene plasmon polaritons in graphene nanoribbon waveguides and experimentally observe the excitation of the graphene plasmon polaritons in a continuous graphene monolayer. We show that graphene nanoribbon bends do not induce any additional loss...... and nanofocusing occurs in a tapered graphene nanoriboon, and we experimentally demonstrate the excitation of graphene plasmon polaritonss in a continuous graphene monolayer assisted by a two-dimensional subwavelength silicon grating....

  6. Suppression of radiation excitation in focusing environment

    International Nuclear Information System (INIS)

    Huang, Z.; Ruth, R.D.

    1996-12-01

    Radiation damping and quantum excitation in an electron damping ring and a straight focusing channel are reviewed. They are found to be the two limiting cases in the study of a general bending and focusing combined system. In the intermediate regime where the radiation formation length is comparable to the betatron wavelength, quantum excitation can be exponentially suppressed by focusing field. This new regime may have interesting applications in the generation of ultra-low emittance beams

  7. High energy excitations in itinerant ferromagnets

    International Nuclear Information System (INIS)

    Prange, R.E.

    1984-01-01

    Itinerant magnets, those whose electrons move throughout the crystal, are described by band theory. Single particle excitations offer confirmation of band theory, but their description requires important corrections. The energetics of magnetism in iron and nickel is also described in band theory but requires complex bands. Magnetism above the critical temperature and the location of the critical temperature offer discriminants between the two major models of magnetism at high temperature and can be addressed by high energy excitations

  8. Excitation of giant resonances in heavy ion collisions

    International Nuclear Information System (INIS)

    Kuehn, W.

    1991-01-01

    Introduction: What are Giant Resonances? General Features of Giant Resonances, Macroscopic Description and Classification, Basic Excitation Mechanisms, Decay Modes, Giant Resonances Built on Excited States, Relativistic Coulomb Excitation of Giant Resonances, Experimental Situation. (orig.)

  9. Proton-proton elastic scattering excitation functions at intermediate energies: Cross sections and analyzing powers

    CERN Document Server

    Hinterberger, F; Altmeier, M; Bauer, F; Bisplinghoff, J; Büsser, K; Busch, M; Colberg, T; Diehl, O; Dohrmann, F; Engelhardt, H P; Eversheim, P D; Felden, O; Gebel, R; Glende, M; Greiff, J; Gross-Hardt, R; Hinterberger, F; Jahn, R; Jonas, E; Krause, H; Langkau, R; Lindemann, T; Lindlein, J; Maier, R; Maschuw, R; Mayer-Kuckuk, T; Meinerzhagen, A; Naehle, O; Prasuhn, D; Rohdjess, H; Rosendaal, D; Von Rossen, P; Schirm, N; Schulz-Rojahn, M; Schwarz, V; Scobel, W; Trelle, H J; Weise, E; Wellinghausen, A; Woller, K; Ziegler, R

    2000-01-01

    The EDDA experiment at the cooler synchrotron COSY measures proton-proton elastic scattering excitation functions in the momentum range 0.8 - 3.4 GeV/c. In phase 1 of the experiment, spin-averaged differential cross sections were measured continuously during acceleration with an internal polypropylene (CH sub 2) fiber target, taking particular care to monitor luminosity as a function of beam momentum. In phase 2, excitation functions of the analyzing power A sub N and the polarization correlation parameters A sub N sub N , A sub S sub S and A sub S sub L are measured using a polarized proton beam and a polarized atomic hydrogen beam target. The paper presents recent d sigma/d OMEGA and A sub N data. The results provide excitation functions and angular distributions of high precision and internal consistency. No evidence for narrow structures was found. The data are compared to recent phase shift solutions.

  10. Dynamic behavior of three-dimensional composite beam under flapwise excitation

    Energy Technology Data Exchange (ETDEWEB)

    Eftekhari, Mojtaba [Dept. of Mechanical Engineering, Shahid Bahonar University of Kerman, Kerman (Iran, Islamic Republic of)

    2016-08-15

    In this paper, dynamic response of a symmetrically laminated composite beam is studied under harmonic base excitation. The base is subjected to flapwise excitation tuned to the primary resonance in the presence of 2:1 internal resonance between the out-of-plane bending motion and the in-plane bending and torsional motions. In literature, modified modulation equations of composite beam have been derived and the stability of fixed points has been investigated in frequency and forced responses. However, post-critical behavior of the modulation equations is studied in this study. In bifurcation diagrams sketched near primary and internal resonances, it appears that detuning the flapwise excitation amplitude causes phenomena like jumps, period doubling, multi and quasi-periodic solutions to occur.

  11. Stick-Slip Analysis of a Drill String Subjected to Deterministic Excitation and Stochastic Excitation

    Directory of Open Access Journals (Sweden)

    Hongyuan Qiu

    2016-01-01

    Full Text Available Using a finite element model, this paper investigates the torsional vibration of a drill string under combined deterministic excitation and random excitation. The random excitation is caused by the random friction coefficients between the drill bit and the bottom of the hole and assumed as white noise. Simulation shows that the responses under random excitation become random too, and the probabilistic distribution of the responses at each discretized time instant is obtained. The two points, entering and leaving the stick stage, are examined with special attention. The results indicate that the two points become random under random excitation, and the distributions are not normal even when the excitation is assumed as Gaussian white noise.

  12. A study of Rh xS y/C and RuSe x/C as methanol-tolerant oxygen reduction catalysts for mixed-reactant fuel cell applications

    International Nuclear Information System (INIS)

    Papageorgopoulos, Dimitrios C.; Liu, Fang; Conrad, Olaf

    2007-01-01

    For efficient operation, mixed-reactant fuel cells utilise highly selective anode and cathode electrocatalysts. While platinum and its alloys are the most widely used ORR electrocatalysts in conventional DMFCs, they suffer from both their very high activity for methanol oxidation and their inherent cost. Platinum-free precious metal chalcogenides have been suggested as alternatives with comparable oxygen reduction activity in the presence of methanol. Of these, commercially available carbon supported rhodium sulphide and developmental ruthenium selenium were electrochemically tested and assessed for their potential as selective ORR cathode catalysts. Both materials exhibited oxygen reduction activity approaching that of platinum, albeit at potentials 150 and 80 mV more negative. The three materials' ability to maintain their oxygen reduction activity in the presence of methanol ranks ruthenium selenium > rhodium sulphide >> platinum

  13. Analysis of River sediments from the Tigre river (Venezuela) by radioisotope excited x-ray fluorescence

    International Nuclear Information System (INIS)

    LaBrecque, J.J.; Rosales, P.A.; Schorin, H.

    1985-01-01

    This paper describes qualitative elemental scans by both energy dispersive (radioisotope excited) and conventional wavelength dispersive x-ray fluorescence of different grain size fractions of river sediments. An internal standard thin-film technique was used. The precision of Rb, Sr, Y and Zr determination for SY-3 standard reference rock and one real sample for five independently prepared samples is demonstrated

  14. X-ray excited optical luminescence studies on the system BaXY (X ...

    Indian Academy of Sciences (India)

    Home; Journals; Pramana – Journal of Physics; Volume 65; Issue 2. X-ray excited optical luminescence studies on the system Ba (, =F, Cl, Br, I) ... India; Department of Chemical Engineering, National Taiwan University, Republic of China ... Proceedings of the International Workshop/Conference on Computational ...

  15. Coulomb excitation of radioactive 20, 21Na

    Science.gov (United States)

    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

    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 γ -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 ( λ 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( λ 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 μ_ 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( λ L) values for the proton dripline nucleus 20Na .-1

  16. Studies of interstellar vibrationally-excited molecules

    International Nuclear Information System (INIS)

    Ziurys, L.M.; Snell, R.L.; Erickson, N.R.

    1986-01-01

    Several molecules thus far have been detected in the ISM in vibrationally-excited states, including H 2 , SiO, HC 3 N, and CH 3 CN. In order for vibrational-excitation to occur, these species must be present in unusually hot and dense gas and/or where strong infrared radiation is present. In order to do a more thorough investigation of vibrational excitation in the interstellar medium (ISM), studies were done of several mm-wave transitions originating in excited vibrational modes of HCN, an abundant interstellar molecule. Vibrationally-excited HCN was recently detected toward Orion-KL and IRC+10216, using a 12 meter antenna. The J=3-2 rotational transitions were detected in the molecule's lowest vibrational state, the bending mode, which is split into two separate levels, due to l-type doubling. This bending mode lies 1025K above ground state, with an Einstein A coefficient of 3.6/s. The J=3-2 line mode of HCN, which lies 2050K above ground state, was also observed toward IRC+10216, and subsequently in Orion-KL. Further measurements of vibrationally-excited HCN were done using a 14 meter telescope, which include the observations of the (0,1,0) and (0,2,0) modes towards Orion-KL, via their J=3-2 transitions at 265-267 GHz. The spectrum of the J=3-2 line in Orion taken with the 14 meter telescope, is shown, along with a map, which indicates that emission from vibrationally-excited HCN arises from a region probably smaller than the 14 meter telescope's 20 arcsec beam

  17. van der Waals interaction of excited media

    International Nuclear Information System (INIS)

    Sherkunov, Yury

    2005-01-01

    The Casimir interaction between two media of ground-state atoms is well described with the help of the Lifshitz formula depending upon the permittivity of the media. We will show that this formula is in contradiction with experimental evidence for excited atoms. We calculate the Casimir force between two atoms if one or both of them are excited. We use methods of quantum electrodynamics specially derived for the problem. It enables us to take into account the excited-state radiation widths of atoms. Then we calculate the force between the excited atom and medium of ground-state atoms. The results are in agreement with the ones obtained by other authors who used perturbation theory or linear response theory. Generalization of our results to the case of the interaction between two media of excited atoms results in a formula, which is in not only in quantitative, but in qualitative contradiction with the Lifshitz formula. This contradiction disappears if the media of ground-state atoms are considered. Moreover, our result does not include the permittivity of the media. It includes a quantity which differs from the permittivity only for excited atoms. The main features of our results are as follows. The interaction is resonant, the force may be either attractive or repulsive depending on the resonant frequencies of the atoms of different media, and the value of the Casimir force may be several orders of magnitude lager than that predicted by the Lifshitz formula. The features mentioned here are in agreement with known experimental and theoretical evidence obtained by many authors for the interaction of a single excited atom with dielectric media

  18. The rotational excitation of HF by H

    Science.gov (United States)

    Desrousseaux, Benjamin; Lique, François

    2018-06-01

    The HF molecule is a key tracer of molecular hydrogen in diffuse interstellar medium (ISM). Accurate modelling of the HF abundance in such media requires one to model its excitation by both radiation and collisions. In diffuse ISM, the dominant collisional partners are atomic and molecular hydrogen. We report quantum time-independent calculations of collisional cross-sections and rate coefficients for the rotational excitation of HF by H. The reactive hydrogen exchange channels are taken into account in the scattering calculations. For the first time, HF-H rate coefficients are provided for temperature ranging from 10 to 500 K. The strongest collision-induced rotational HF transitions are those with Δj = 1, and the order of magnitude of the new HF-H rate coefficients is similar to that of the HF-H2 ones previously computed. As a first application, we simulate the excitation of HF by both H and H2 in typical diffuse ISM. We show that, depending on the rotational transition, hydrogen atoms increase or decrease the simulated excitation temperatures compared to collisional excitation only due to H2 molecules. Such results suggest that the new HF-H collisional data have to be used for properly modelling the abundance of HF in diffuse ISM.

  19. Photoionization dynamics of excited molecular states

    International Nuclear Information System (INIS)

    Dehmer, J.L.; O'Halloran, M.A.; Tomkins, F.S.; Dehmer, P.M.; Pratt, S.T.

    1987-01-01

    Resonance Enhanced Multiphoton Ionization (REMPI) utilizes tunable dye lasers to ionize an atom or molecule by first preparing an excited state by multiphoton absorption and then ionizing that state before it can decay. This process is highly selective with respect to both the initial and resonant intermediate states of the target, and it can be extremely sensitive. In addition, the products of the REMPI process can be detected as needed by analyzing the resulting electrons, ions, fluorescence, or by additional REMPI. This points to a number of opportunities for exploring excited state physics and chemistry at the quantum-state-specific level. Here we will first give a brief overview of the large variety of experimental approaches to excited state phenomena made possible by REMPI. Then we will examine in more detail, recent studies of the three photon resonant, four photon (3 + 1) ionization of H 2 via the C 'PI/sup u/ state. Strong non-Franck-Condon behavior in the photoelectron spectra of this nominally simple Rydberg state has led to the examination of a variety of dynamical mechanisms. Of these, the role of doubly excited autoionizing states now seems decisive. Progress on photoelectron studies of autoionizing states in H 2 , excited in a (2 + 1) REMPI process via the E, F 1 Σ/sub g/ + will also be briefly discussed. 26 refs., 7 figs

  20. Electron-beam-excited gas laser research

    International Nuclear Information System (INIS)

    Johnson, A.W.; Gerardo, J.B.; Patterson, E.L.; Gerber, R.A.; Rice, J.K.; Bingham, F.W.

    1975-01-01

    Net energy gain in laser fusion places requirements on the laser that are not realized by any existing laser. Utilization of relativistic electron beams (REB's), a relatively new source for the excitation of gas laser media, may lead to new lasers that could satisfy these requirements. Already REB's have been utilized to excite gas laser media and produce gas lasers that have not been produced as successfully any other way. Electron-beam-excitation has produced electronic-transition dimer lasers that have not yet been produced by any other excitation scheme (for example, Xe 2 / sup *(1)/, Kr:O(2 1 S)/sup 2/, KrF/sup *(3)/). In addition, REB's have initiated chemical reactions to produce HF laser radiation with unique and promising results. Relativistic-electron-beam gas-laser research is continuing to lead to new lasers with unique properties. Results of work carried out at Sandia Laboratories in this pioneering effort of electron-beam-excited-gas lasers are reviewed. (U.S.)

  1. Detection of interstellar vibrationally excited HCN

    International Nuclear Information System (INIS)

    Ziurys, L.M.; Turner, B.E.

    1986-01-01

    Vibrationally excited HCN has been observed for the first time in the interstellar medium. The J = 3-2 rotational transitions of the l-doubled (0,1/sup 1d/,1c, 0) bending mode of HCN have been detected toward Orion-KL and IRC +10216. In Orion, the overall column density in the (0,1,0) mode, which exclusively samples the ''hot core,'' is 1.7-10 16 cm -2 and can be understood in terms of the ''doughnut'' model for Orion. The ground-state HCN column density implied by the excited-state observations is 2.3 x 10 18 cm -2 in the hot core, at least one order of magnitude greater than the column densities derived for HCN in its spike and plateau/doughnut components. Radiative excitation by 14 μm flux from IRc2 accounts for the (0,1,0) population provided the hot core is approx.6-7 x 10 16 cm distant from IRc2, in agreement with the ''cavity'' model for KL. Toward IRC +10216 we have detected J = 3-2 transitions of both (0,1/sup 1c/,/sup 1d/,0) and (0,2 0 ,0) excited states. The spectral profiles have been modeled to yield abundances and excitation conditions throughout the expanding envelope

  2. Exciplex formation accompanied with excitation quenching.

    Science.gov (United States)

    Fedorenko, Stanislav G; Burshtein, Anatoly I

    2010-04-08

    The competence of the reversible exciplex formation and parallel quenching of excitation (by electron or energy transfer) was considered using a non-Markovian pi-forms approach, identical to integral encounter theory (IET). General equations accounting for the reversible quenching and exciplex formation are derived in the contact approximation. Their general solution was obtained and adopted to the most common case when the ground state particles are in great excess. Particular cases of only photoionization or just exciplex formation separately studied earlier by means of IET are reproduced. In the case of the irreversible excitation quenching, the theory allows specifying the yields of the fluorescence and exciplex luminescence, as well as the long time kinetics of excitation and exciplex decays, in the absence of quenching. The theory distinguishes between the alternative regimes of (a) fast equilibration between excitations and exciplexes followed by their decay with a common average rate and (b) the fastest and deep excitation decay followed by the weaker and slower delayed fluorescence, backed by exciplex dissociation.

  3. Fully phase-encoded MRI near metallic implants using ultrashort echo times and broadband excitation.

    Science.gov (United States)

    Wiens, Curtis N; Artz, Nathan S; Jang, Hyungseok; McMillan, Alan B; Koch, Kevin M; Reeder, Scott B

    2018-04-01

    To develop a fully phase-encoded MRI method for distortion-free imaging near metallic implants, in clinically feasible acquisition times. An accelerated 3D fully phase-encoded acquisition with broadband excitation and ultrashort echo times is presented, which uses a broadband radiofrequency pulse to excite the entire off-resonance induced by the metallic implant. Furthermore, fully phase-encoded imaging is used to prevent distortions caused by frequency encoding, and to obtain ultrashort echo times for rapidly decaying signal. Phantom and in vivo acquisitions were used to describe the relationship among excitation bandwidth, signal loss near metallic implants, and T 1 weighting. Shorter radiofrequency pulses captured signal closer to the implant by improving spectral coverage and allowing shorter echo times, whereas longer pulses improved T 1 weighting through larger maximum attainable flip angles. Comparisons of fully phase-encoded acquisition with broadband excitation and ultrashort echo times to T 1 -weighted multi-acquisition with variable resonance image combination selective were performed in phantoms and subjects with metallic knee and hip prostheses. These acquisitions had similar contrast and acquisition efficiency. Accelerated fully phase-encoded acquisitions with ultrashort echo times and broadband excitation can generate distortion free images near metallic implants in clinically feasible acquisition times. Magn Reson Med 79:2156-2163, 2018. © 2017 International Society for Magnetic Resonance in Medicine. © 2017 International Society for Magnetic Resonance in Medicine.

  4. Characterization of internal dosimetry practices

    International Nuclear Information System (INIS)

    Traub, R.J.; Heid, K.R.; Mann, J.C.

    1983-01-01

    Current practices in internal dosimetry at DOE facilities were evaluated with respect to consistency among DOE Contractors. All aspects of an internal dosimetry program were addressed. Items considered include, but are not necessarily limited to, record systems and ease of information retrieval; ease of integrating internal dose and external dose; modeling systems employed, including ability to modify models depending on excretion data, and verification of computer codes utilized; bioassay procedures, including quality control; and ability to relate air concentration data to individual workers and bioassay data. Feasibility of uranium analysis in solution by laser fluorescence excitation at uranium concentrations of one part per billion was demonstrated

  5. Effect of xanthophyll composition on the chlorophyll excited state lifetime in plant leaves and isolated LHCII

    International Nuclear Information System (INIS)

    Johnson, Matthew P.; Zia, Ahmad; Horton, Peter; Ruban, Alexander V.

    2010-01-01

    Xanthophyll excited states have been implicated by transient absorption and two-photon excitation studies in playing a key role in the regulation of photosynthetic light harvesting via photoprotective energy dissipation. For any proposed quenching mechanism to be effective it must reduce the chlorophyll excited state lifetime from 2 ns to ∼0.5-0.4 ns. In the presented study the effect of xanthophyll composition on the chlorophyll excited state lifetime in Arabidopsis leaves in the light harvesting (F m ) and photoprotective (NPQ) states was determined. The data was compared to the chlorophyll excited state lifetime of native isolated LHCII and CP26 in detergent micelles with varying xanthophyll composition. It was found that although the differences in xanthophyll composition between LHC complexes from various Arabidopsis mutants were sufficient to explain the varying F m lifetime (and varying PSII efficiency), they were not of a sufficient scale to fully explain the observed differences in the NPQ lifetimes. Only when the LHC complexes were exposed to a low detergent/low pH media, a condition known to mimic the conformational state of LHCII associated with NPQ in vivo, were variations in excited state lifetime large enough to explain the differences observed in leaves. Furthermore, the data reveal that the replacement of lutein by either zeaxanthin or violaxanthin in the internal xanthophyll binding sites of LHCII and CP26 reduces the efficiency of energy dissipation in the photoprotective state in leaves and isolated complexes.

  6. Spiral ganglion cell site of excitation I: comparison of scala tympani and intrameatal electrode responses.

    Science.gov (United States)

    Cartee, Lianne A; Miller, Charles A; van den Honert, Chris

    2006-05-01

    To determine the site of excitation on the spiral ganglion cell in response to electrical stimulation similar to that from a cochlear implant, single-fiber responses to electrical stimuli delivered by an electrode positioned in the scala tympani were compared to responses from stimuli delivered by an electrode placed in the internal auditory meatus. The response to intrameatal stimulation provided a control set of data with a known excitation site, the central axon of the spiral ganglion cell. For both intrameatal and scala tympani stimuli, the responses to single-pulse, summation, and refractory stimulus protocols were recorded. The data demonstrated that summation pulses, as opposed to single pulses, are likely to give the most insightful measures for determination of the site of excitation. Single-fiber summation data for both scala tympani and intrameatally stimulated fibers were analyzed with a clustering algorithm. Combining cluster analysis and additional numerical modeling data, it was hypothesized that the scala tympani responses corresponded to central excitation, peripheral excitation adjacent to the cell body, and peripheral excitation at a site distant from the cell body. Fibers stimulated by an intrameatal electrode demonstrated the greatest range of jitter measurements indicating that greater fiber independence may be achieved with intrameatal stimulation.

  7. Development of PZT-excited stroboscopic shearography for full-field nondestructive evaluation.

    Science.gov (United States)

    Asemani, Hamidreza; Park, Jinwoo; Lee, Jung-Ryul; Soltani, Nasser

    2017-05-01

    Nondestructive evaluation using shearography requires a way to stress the inspection target. This technique is able to directly measure the displacement gradient distribution on the object surface. Shearography visualizes the internal structural damages as the anomalous pattern in the shearograpic fringe pattern. A piezoelectric (PZT) excitation system is able to generate loadings in the vibrational, acoustic, and ultrasonic regimes. In this paper, we propose a PZT-excited stroboscopic shearography. The PZT excitation could generate vibrational loading, a stationary wavefield, and a nonstationary propagation wave to fulfill the external loading requirement of shearography. The sweeping of the PZT excitation frequency, the formation of a standing wave, and a small shearing to suppress the incident wave were powerful controllable tools to detect the defects. The sweeping of the PZT excitation frequency enabled us to determine one of the defect-sensitive frequencies almost in real time. In addition, because the defect sensitive frequencies always existed in wide and plural ranges, the risk of the defect being overlooked by the inspector could be alleviated. The results of evaluation using stroboscopic shearography showed that an artificial 20 mm-diameter defect could be visualized at the excitation frequencies of 5-8 kHz range and 12.5-15.5 kHz range. This technique provided full field reliable and repeatable inspection results. Additionally, the proposed method overcame the important drawback of the time-averaged shearography, being required to identify the resonance vibration frequency sensitive to the defect.

  8. Inelastic scattering of {sup 9}Li and excitation mechanism of its first excited state

    Energy Technology Data Exchange (ETDEWEB)

    Al Falou, H. [Astronomy and Physics Department, Saint Mary' s University, Halifax, Nova Scotia B3H 3C3 (Canada); TRIUMF, Vancouver, British Columbia V6T 2A3 (Canada); Kanungo, R., E-mail: ritu@triumf.ca [Astronomy and Physics Department, Saint Mary' s University, Halifax, Nova Scotia B3H 3C3 (Canada); Andreoiu, C.; Cross, D.S. [Department of Chemistry, Simon Fraser University, Burnaby, British Columbia V5A 1S6 (Canada); Davids, B.; Djongolov, M. [TRIUMF, Vancouver, British Columbia V6T 2A3 (Canada); Gallant, A.T. [TRIUMF, Vancouver, British Columbia V6T 2A3 (Canada); Department of Physics, University of British Columbia, British Columbia V6T 1Z4 (Canada); Galinski, N.; Howell, D. [TRIUMF, Vancouver, British Columbia V6T 2A3 (Canada); Department of Physics, Simon Fraser University, Burnaby, British Columbia V5A 1S6 (Canada); Kshetri, R.; Niamir, D. [TRIUMF, Vancouver, British Columbia V6T 2A3 (Canada); Orce, J.N. [TRIUMF, Vancouver, British Columbia V6T 2A3 (Canada); Department of Physics, University of the Western Cape, P/B X17, Bellville, ZA-7535 (South Africa); Shotter, A.C. [Department of Physics and Astronomy, University of Edinburgh, Edinburgh (United Kingdom); Sjue, S. [TRIUMF, Vancouver, British Columbia V6T 2A3 (Canada); Tanihata, I. [Research Center for Nuclear Physics, Osaka University, Mihogaoka, Ibaraki, Osaka 567 0047 (Japan); Thompson, I.J. [Lawrence Livermore National Laboratory, Livermore, CA 94551 (United States); Triambak, S. [TRIUMF, Vancouver, British Columbia V6T 2A3 (Canada); Uchida, M. [Astronomy and Physics Department, Saint Mary' s University, Halifax, Nova Scotia B3H 3C3 (Canada); Walden, P. [TRIUMF, Vancouver, British Columbia V6T 2A3 (Canada); Wiringa, R.B. [Physics Division, Argonne National Laboratory, Argonne, IL 60439 (United States)

    2013-04-25

    The first measurement of inelastic scattering of {sup 9}Li from deuterons at the ISAC facility is reported. The measured angular distribution for the first excited state confirms the nature of excitation to be an E2 transition. The quadrupole deformation parameter is extracted from an analysis of the angular distribution.

  9. Inelastic scattering of 9Li and excitation mechanism of its first excited state

    International Nuclear Information System (INIS)

    Al Falou, H.; Kanungo, R.; Andreoiu, C.; Cross, D.S.; Davids, B.; Djongolov, M.; Gallant, A.T.; Galinski, N.; Howell, D.; Kshetri, R.; Niamir, D.; Orce, J.N.; Shotter, A.C.; Sjue, S.; Tanihata, I.; Thompson, I.J.; Triambak, S.; Uchida, M.; Walden, P.; Wiringa, R.B.

    2013-01-01

    The first measurement of inelastic scattering of 9 Li from deuterons at the ISAC facility is reported. The measured angular distribution for the first excited state confirms the nature of excitation to be an E2 transition. The quadrupole deformation parameter is extracted from an analysis of the angular distribution

  10. Springing response due to bidirectional wave excitation

    DEFF Research Database (Denmark)

    Vidic-Perunovic, Jelena

    2005-01-01

    theories deal with the unidirectional wave excitation. This is quite standard. The problem is how to include more than one directional wave systems described by a wave spectrum with arbitrary heading. The main objective of the present work has been to account for the additional second-order springing......-linear (second order) high frequency springing analyses with unidirectional wave excitation are much more scattered. Some of the reasons are different level of wave excitation accounted in the different Executive Summary ivtheories, inclusion of additional hydrodynamic phenomena e.g. slamming in the time...... because, to the author's knowledge, this is the first time that the wave data were collected simultaneously with stress records on the deck of the ship. This is highly appreciated because one can use the precise input and not only the most probable sea state statistics. The actual picture of the sea waves...

  11. Elementary excitations in single-chain magnets

    Science.gov (United States)

    Lutz, Philipp; Aguilà, David; Mondal, Abhishake; Pinkowicz, Dawid; Marx, Raphael; Neugebauer, Petr; Fâk, Björn; Ollivier, Jacques; Clérac, Rodolphe; van Slageren, Joris

    2017-09-01

    Single-chain magnets (SCMs) are one-dimensional coordination polymers or spin chains that display slow relaxation of the magnetization. Typically their static magnetic properties are described by the Heisenberg model, while the description of their dynamic magnetic properties is based on an Ising-like model. The types of excitations predicted by these models (collective vs localized) are quite different. Therefore we probed the nature of the elementary excitations for two SCMs abbreviated Mn2Ni and Mn2Fe , as well as a mononuclear derivative of the Mn2Fe chain, by means of high-frequency electron paramagnetic resonance spectroscopy (HFEPR) and inelastic neutron scattering (INS). We find that the HFEPR spectra of the chains are clearly distinct from those of the monomer. The momentum transfer dependence of the INS intensity did not reveal significant dispersion, indicating an essentially localized nature of the excitations. At the lowest temperatures these are modified by the occurrence of short-range correlations.

  12. Nerve excitability in the rat forelimb

    DEFF Research Database (Denmark)

    Arnold, Ria; Moldovan, Mihai; Rosberg, Mette Romer

    2017-01-01

    Background Nerve excitability testing by threshold-tracking is the only available method to study axonal ion channel function and membrane potential in the clinical setting. The measures are, however, indirect and the interpretation of neuropathic changes remains challenging. The same multiple...... measures of axonal excitability were adapted to further explore the pathophysiological changes in rodent disease models under pharmacologic and genetic manipulations. These studies are typically limited to the investigation of the “long nerves” such as the tail or the tibial nerves. New method We introduce...... a novel setup to explore the ulnar nerve excitability in rodents. We provide normative ulnar data in 11 adult female Long Evans rats under anaesthesia by comparison with tibial and caudal nerves. Additionally, these measures were repeated weekly on 3 occasions to determine the repeatability of these tests...

  13. Pilot testing of a hydraulic bridge exciter

    Directory of Open Access Journals (Sweden)

    Andersson Andreas

    2015-01-01

    Full Text Available This paper describes the development of a hydraulic bridge exciter and its first pilot testing on a full scale railway bridge in service. The exciter is based on a hydraulic load cylinder with a capacity of 50 kN and is intended for controlled dynamic loading up to at least 50 Hz. The load is applied from underneath the bridge, enabling testing while the railway line is in service. The system is shown to produce constant load amplitude even at resonance. The exciter is used to experimentally determine frequency response functions at all sensor locations, which serve as valuable input for model updating and verification. An FE-model of the case study bridge has been developed that is in good agreement with the experimental results.

  14. Encryption in Chaotic Systems with Sinusoidal Excitations

    Directory of Open Access Journals (Sweden)

    G. Obregón-Pulido

    2014-01-01

    Full Text Available In this contribution an encryption method using a chaotic oscillator, excited by “n” sinusoidal signals, is presented. The chaotic oscillator is excited by a sum of “n” sinusoidal signals and a message. The objective is to encrypt such a message using the chaotic behavior and transmit it, and, as the chaotic system is perturbed by the sinusoidal signal, the transmission security could be increased due to the effect of such a perturbation. The procedure is based on the regulation theory and consider that the receiver knows the frequencies of the perturbing signal, with this considerations the algorithm estimates the excitation in such a way that the receiver can cancel out the perturbation and all the undesirable dynamics in order to produce only the message. In this way we consider that the security level is increased.

  15. Electron-impact excitation of Zn II

    International Nuclear Information System (INIS)

    Msezane, A.Z.; Henry, R.J.W.

    1982-01-01

    Collision strengths are calculated for excitation of Zn II from the 4s ground state to excited states 4p, 3d 9 4s 2 , 5s, and 4d in a five-state close-coupling approximation for the electron-impact energy range 15 5 3d 10 4s 2 in a two-state close-coupling approximation for the same energy range. Accurate target functions are used in the expansion. Very good agreement with measurements of absolute emission cross sections of Rogers et al. is obtained for energy region 15< E<100 eV, when cascade contributions are included. Poorer agreement is obtained with experiment for excitation of the 5s state, owing to sensitivities in the close-coupling approximation

  16. Adaptive transition rates in excitable membranes

    Directory of Open Access Journals (Sweden)

    Shimon Marom

    2009-02-01

    Full Text Available Adaptation of activity in excitable membranes occurs over a wide range of timescales. Standard computational approaches handle this wide temporal range in terms of multiple states and related reaction rates emanating from the complexity of ionic channels. The study described here takes a different (perhaps complementary approach, by interpreting ion channel kinetics in terms of population dynamics. I show that adaptation in excitable membranes is reducible to a simple Logistic-like equation in which the essential non-linearity is replaced by a feedback loop between the history of activation and an adaptive transition rate that is sensitive to a single dimension of the space of inactive states. This physiologically measurable dimension contributes to the stability of the system and serves as a powerful modulator of input-output relations that depends on the patterns of prior activity; an intrinsic scale free mechanism for cellular adaptation that emerges from the microscopic biophysical properties of ion channels of excitable membranes.

  17. Collective excitations in itinerant spiral magnets

    International Nuclear Information System (INIS)

    Kampf, A.P.

    1996-01-01

    We investigate the coupled charge and spin collective excitations in the spiral phases of the two-dimensional Hubbard model using a generalized random-phase approximation. Already for small doping the spin-wave excitations are strongly renormalized due to low-energy particle-hole excitations. Besides the three Goldstone modes of the spiral state the dynamical susceptibility reveals an extra zero mode for low doping and strong coupling values signaling an intrinsic instability of the homogeneous spiral state. In addition, near-zero modes are found in the vicinity of the spiral pitch wave number for out-of-plane spin fluctuations. Their origin is found to be the near degeneracy with staggered noncoplanar spiral states which, however, are not the lowest energy Hartree-Fock solutions among the homogeneous spiral states. copyright 1996 The American Physical Society

  18. Triple Giant Resonance Excitations: A Microscopic Approach

    International Nuclear Information System (INIS)

    Lanza, E.G.; Andres, M.V.; Catara, F.; Chomaz, Ph.; Fallot, M.; Scarpaci, J.A.

    2007-01-01

    We present, for the first time, microscopic calculations of inelastic cross sections of the triple excitation of giant resonances induced by heavy ion probes. We start from a microscopic approach based on RPA. The mixing of three-phonon states among themselves and with two- and one-phonon states is considered within a boson expansion with Pauli corrections. In this way we go beyond the standard harmonic approximations and get anharmonic excitation spectra. At the same time we also introduce non-linearities in the external field. The calculations are done by solving semiclassical coupled channel equations, the channels being superpositions of one-, two- and three-phonon states. Previous calculations for the Double Giant Resonance excitation show good agreement with experimental cross sections. The inclusion of the three phonon components confirms the previous results for the DGR and produces a strong increase in the Triple GR energy region

  19. Elementary excitations and phase transformations in solids

    International Nuclear Information System (INIS)

    Cowley, R.A.

    1985-01-01

    Neutron scattering is and will continue to be a uniquely powerful tool for the study of elementary excitations and phase transformations in solids. The paper examines a few recent experiments on molecular crystals, superionic materials, paramagnetic scattering and phase transitions to see what experimental features made these experiments possible, and hence to make suggestions about future needs. It is concluded that new instruments will extend the scope of neutron scattering studies to new excitations, that there is a need for higher resolution, particularly for phase transition studies, and that it will be important to use intensity information, discrimination against unwanted inelastic processes and polarization analysis to reliably measure the excitations in new materials. (author)

  20. Electronic-excitation energy transfer in heterogeneous dye solutions under laser excitation

    International Nuclear Information System (INIS)

    Levshin, L.V.; Mukushev, B.T.; Saletskii, A.M.

    1995-01-01

    An experimental study has been made of electronic-excitation energy transfer (EEET) among dye molecules of different types for different exciting-fight wavelengths and temperatures. Upon selective laser excitation of the donor, the inhomogeneous broadening of molecular levels increases the probability of EEET from the donor to acceptor molecules. The efficiency of this process is directly proportional to the acceptor molecule concentration and is temperature dependent. The EEET is accompanied by the spectral migration of energy among donor molecules, which reduces the fluorescence quantum efficiency of the donor. Increasing the frequency of the exciting light decreases in the donor fluorescence quantum efficiency. An increase in the acceptor molecule concentration results in a decrease of the spectral migration of excitation in the donor molecule system. 5 refs., 5 figs

  1. Characterization of weakly excited final states by shakedown spectroscopy of laser-excited potassium

    International Nuclear Information System (INIS)

    Schulz, J.; Heinaesmaeki, S.; Aksela, S.; Aksela, H.; Sankari, R.; Rander, T.; Lindblad, A.; Bergersen, H.; Oehrwall, G.; Svensson, S.; Kukk, E.

    2006-01-01

    3p shakedown spectra of laser excited potassium atoms as well as direct 3p photoemission of ground state potassium have been studied. These two excitation schemes lead to the same final states and thereby provide a good basis for a detailed study of the 3p 5 (4s3d) 1 configurations of singly ionized potassium and the photoemission processes leading to these configurations. The comparison of direct photoemission from the ground state and conjugate shakedown spectra from 4p 1/2 laser excited potassium made it possible to experimentally determine the character of final states that are only weakly excited in the direct photoemission but have a much higher relative intensity in the shakedown spectrum. Based on considerations of angular momentum and parity conservation the excitation scheme of the final states can be understood

  2. Nonlinear Characteristics of Randomly Excited Transonic Flutter

    DEFF Research Database (Denmark)

    Christiansen, Lasse Engbo; Lehn-Schiøler, Tue; Mosekilde, Erik

    2002-01-01

    . When this model is extended by the introduction of nonlinear terms, it can reproduce the subcritical Hopf bifurcation. We hereafter consider the effects of subjecting simplified versions of the model to random external excitations representing the fluctuations present in the airflow. These models can......The paper describes the effects of random external excitations on the onset and dynamical characteristics of transonic flutter (i.e. large-amplitude, self-sustained oscillations) for a high aspect ratio wing. Wind tunnel experiments performed at the National Aerospace Laboratory (NAL) in Japan have...

  3. Computing correct truncated excited state wavefunctions

    Science.gov (United States)

    Bacalis, N. C.; Xiong, Z.; Zang, J.; Karaoulanis, D.

    2016-12-01

    We demonstrate that, if a wave function's truncated expansion is small, then the standard excited states computational method, of optimizing one "root" of a secular equation, may lead to an incorrect wave function - despite the correct energy according to the theorem of Hylleraas, Undheim and McDonald - whereas our proposed method [J. Comput. Meth. Sci. Eng. 8, 277 (2008)] (independent of orthogonality to lower lying approximants) leads to correct reliable small truncated wave functions. The demonstration is done in He excited states, using truncated series expansions in Hylleraas coordinates, as well as standard configuration-interaction truncated expansions.

  4. Clinical Comparison of Pulse and Chirp Excitation

    DEFF Research Database (Denmark)

    Pedersen, Morten Høgholm; Misaridis, T.; Jensen, Jørgen Arendt

    2002-01-01

    Coded excitation (CE) using frequency modulated signals (chirps) combined with modified matched filtering has earlier been presented showing promising results in simulations and in-vitro. In this study an experimental ultrasound system is evaluated in a clinical setting, where image sequences...... and short pulse excitation to simultaneously produce identical image sequences using both techniques. Nine healthy male volunteers were scanned in abdominal locations. All sequences were evaluated by 3 skilled medical doctors, blinded to each other and to the technique used. They assessed the depth (1...

  5. Electron-impact excitation of molecular ions

    International Nuclear Information System (INIS)

    Neufeld, D.A.; Dalgarno, A.

    1989-01-01

    A simple expression is derived that relates the rate coefficient for dipole-allowed electron-impact excitation of a molecular ion in the Coulomb-Born approximation to the Einstein A coefficient for the corresponding radiative decay. Results are given for several molecular ions of astrophysical interest. A general analytic expression is obtained for the equilibrium rotational level populations in the ground vibrational state of any molecular ion excited by collisions with electrons. The expression depends only upon the electron temperature, the electron density, and the rotational constant of the molecular ion. A similar expression is obtained for neutral polar molecules

  6. Spectra from foil-excited molybdenum ions

    International Nuclear Information System (INIS)

    Johnson, B.M.; Jones, K.W.; Cecchi, J.L.; Kruse, T.H.

    1978-01-01

    The extreme-ultraviolet spectra (5 to 55 nm) for foil-excited molybdenum ions have been measured using 22 to 200 MeV beams from the Brookhaven National Laboratory MP tandem Van de Graaff accelerator facility, 20 μg/cm 2 C stripping foils, and a grazing incidence spectrometer. The mean ion charge states (13 to 28) and the narrow distribution widths (about 2 charge states) were accurately predictable from experimental parameters. Where possible, comparisons are given with Mo radiation from tokamaks, vacuum sparks, and laser-excited plasmas

  7. From fusion hierarchy to excited state TBA

    International Nuclear Information System (INIS)

    Juettner, G.; Kluemper, A.

    1998-01-01

    Functional relations among the fusion hierarchy of quantum transfer matrices give a novel derivation of the TBA equations, namely without string hypothesis. This is demonstrated for two important models of 1D highly correlated electron systems, the supersymmetric t-J model and the supersymmetric extended Hubbard model. As a consequence, ''the excited state TBA'' equations, which characterize correlation lengths, are explicitly derived for the t-J model. To the authors' knowledge, this is the first explicit derivation of excited state TBA equations for 1D lattice electron systems. (orig.)

  8. Excitation Chains at the Glass Transition

    International Nuclear Information System (INIS)

    Langer, J. S.

    2006-01-01

    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

  9. Topological excitations in U(1) -invariant theories

    International Nuclear Information System (INIS)

    Savit, R.

    1977-01-01

    A class of U(1) -invariant theories in d dimensions is introduced on a lattice. These theories are labeled by a simplex number s, with 1 < or = s < d. The case with s = 1 is the X-Y model; and s = 2 gives compact photodynamics. An exact duality transformation is applied to show that the U(1) -invariant theory in d dimensions with simplex number s is the same as a similar theory in d dimensions but which is Z /sub infinity/-invariant and has simplex number s = d-s. This dual theory describes the topological excitations of the original theory. These excitations are of dimension s - 1

  10. Multipole giant resonances in highly excited nuclei

    International Nuclear Information System (INIS)

    Xia Keding; Cai Yanhuang

    1989-01-01

    The isoscalar giant surface resonance and giant dipole resonance in highly excited nuclei are discussed. Excitation energies of the giant modes in 208 Pb are calculated in a simplified model, using the concept of energy wieghted sum rule (EWSR), and the extended Thomas-Fermi approximation at the finite temperature is employed to describe the finite temperature is employed to describe the finite temperature equilibrium state. It is shown that EWSR and the energy of the resonance depend only weakly on temperature in the system. This weak dependence is analysed

  11. Isovector excitations of N ≠ Z nuclei

    International Nuclear Information System (INIS)

    Passos, E.J.V. de; Menezes, D.P.; Galeao, A.P.N.R.

    1987-09-01

    We show that the method based on the tensor coupling of an appropriate family of isovector excitation operators to the parent isospin multiplet can be used, to advantage, for the correct treatment of the isospin degree of freedom in non isoscalar nuclei. This method is applicable to any isovector excitation operator and for parent states which need not to be of the closed subshells type. As an illustration we apply it to the study of the Gamow-Teller transition strength in 90 Zr. (author) [pt

  12. Phonon excitations in multicomponent amorphous solids

    International Nuclear Information System (INIS)

    Vakarchuk, I.A.; Migal', V.M.; Tkachuk, V.M.

    1988-01-01

    The method of two-time temperature-dependent Green's functions is used to investigate phonon excitations in multicomponent amorphous solids. The equation obtained for the energy spectrum of the phonon excitations takes into account the damping associated with scattering of phonons by structure fluctuations. The quasicrystal approximation is considered, and as an example explicit expressions are obtained for the case of a two-component amorphous solid for the frequencies of the acoustical and optical modes and for the longitudinal and transverse velocities of sound. The damping is investigated

  13. Mexican waves in an excitable medium.

    Science.gov (United States)

    Farkas, I; Helbing, D; Vicsek, T

    2002-09-12

    The Mexican wave, or La Ola, which rose to fame during the 1986 World Cup in Mexico, surges through the rows of spectators in a stadium as those in one section leap to their feet with their arms up, and then sit down again as the next section rises to repeat the motion. To interpret and quantify this collective human behaviour, we have used a variant of models that were originally developed to describe excitable media such as cardiac tissue. Modelling the reaction of the crowd to attempts to trigger the wave reveals how this phenomenon is stimulated, and may prove useful in controlling events that involve groups of excited people.

  14. Elementary spin excitations in ultrathin itinerant magnets

    Energy Technology Data Exchange (ETDEWEB)

    Zakeri, Khalil, E-mail: zakeri@mpi-halle.de

    2014-12-10

    Elementary spin excitations (magnons) play a fundamental role in condensed matter physics, since many phenomena e.g. magnetic ordering, electrical (as well as heat) transport properties, ultrafast magnetization processes, and most importantly electron/spin dynamics can only be understood when these quasi-particles are taken into consideration. In addition to their fundamental importance, magnons may also be used for information processing in modern spintronics. Here the concept of spin excitations in ultrathin itinerant magnets is discussed and reviewed. Starting with a historical introduction, different classes of magnons are introduced. Different theoretical treatments of spin excitations in solids are outlined. Interaction of spin-polarized electrons with a magnetic surface is discussed. It is shown that, based on the quantum mechanical conservation rules, a magnon can only be excited when a minority electron is injected into the system. While the magnon creation process is forbidden by majority electrons, the magnon annihilation process is allowed instead. These fundamental quantum mechanical selection rules, together with the strong interaction of electrons with matter, make the spin-polarized electron spectroscopies as appropriate tools to excite and probe the elementary spin excitations in low-dimensional magnets e.g ultrathin films and nanostructures. The focus is put on the experimental results obtained by spin-polarized electron energy loss spectroscopy and spin-polarized inelastic tunneling spectroscopy. The magnon dispersion relation, lifetime, group and phase velocity measured using these approaches in various ultrathin magnets are discussed in detail. The differences and similarities with respect to the bulk excitations are addressed. The role of the temperature, atomic structure, number of atomic layers, lattice strain, electronic complexes and hybridization at the interfaces are outlined. A possibility of simultaneous probing of magnons and phonons

  15. A Search for Excited Fermions at HERA

    CERN Document Server

    Adloff, C.; Andrieu, B.; Arkadov, V.; Astvatsatourov, A.; Ayyaz, I.; Babaev, A.; Bahr, J.; Baranov, P.; Barrelet, E.; Bartel, W.; Bassler, U.; Bate, P.; Beglarian, A.; Behnke, O.; Beier, C.; Belousov, A.; Benisch, T.; Berger, Christoph; Bernardi, G.; Berndt, T.; Bizot, J.C.; Borras, K.; Boudry, V.; Braunschweig, W.; Brisson, V.; Broker, H.B.; Brown, D.P.; Bruckner, W.; Bruel, P.; Bruncko, D.; Burger, J.; Busser, F.W.; Bunyatyan, A.; Burkhardt, H.; Burrage, A.; Buschhorn, G.; Campbell, A.J.; Cao, Jun; Carli, T.; Caron, S.; Chabert, E.; Clarke, D.; Clerbaux, B.; Collard, C.; Contreras, J.G.; Coughlan, J.A.; Cousinou, M.C.; Cox, B.E.; Cozzika, G.; Cvach, J.; Dainton, J.B.; Dau, W.D.; Daum, K.; Davidsson, M.; Delcourt, B.; Delerue, N.; Demirchyan, R.; De Roeck, A.; De Wolf, E.A.; Diaconu, C.; Dixon, P.; Dodonov, V.; Dowell, J.D.; Droutskoi, A.; Duprel, C.; Eckerlin, Guenter; Eckstein, D.; Efremenko, V.; Egli, S.; Eichler, R.; Eisele, F.; Eisenhandler, E.; Ellerbrock, M.; Elsen, E.; Erdmann, M.; Erdmann, W.; Faulkner, P.J.W.; Favart, L.; Fedotov, A.; Felst, R.; Ferencei, J.; Ferron, S.; Fleischer, M.; Flugge, G.; Fomenko, A.; Foresti, I.; Formanek, J.; Foster, J.M.; Franke, G.; Gabathuler, E.; Gabathuler, K.; Garvey, J.; Gassner, J.; Gayler, Joerg; Gerhards, R.; Ghazaryan, Samvel; Goerlich, L.; Gogitidze, N.; Goldberg, M.; Goodwin, C.; Grab, C.; Grassler, H.; Greenshaw, T.; Grindhammer, Guenter; Hadig, T.; Haidt, D.; Hajduk, L.; Haynes, W.J.; Heinemann, B.; Heinzelmann, G.; Henderson, R.C.W.; Hengstmann, S.; Henschel, H.; Heremans, R.; Herrera, G.; Herynek, I.; Hilgers, M.; Hiller, K.H.; Hladky, J.; Hoting, P.; Hoffmann, D.; Hoprich, W.; Horisberger, R.; Hurling, S.; Ibbotson, M.; Issever, C .; Jacquet, M.; Jaffre, M.; Janauschek, L.; Jansen, D.M.; Janssen, X.; Jemanov, V.; Jonsson, L.; Johnson, D.P.; Jones, M.A.S.; Jung, H.; Kastli, H.K.; Kant, D.; Kapichine, M.; Karlsson, M.; Karschnick, O.; Kaufmann, O.; Kausch, M.; Keil, F.; Keller, N.; Kennedy, J.; Kenyon, I.R.; Kermiche, S.; Kiesling, Christian M.; Klein, M.; Kleinwort, C.; Knies, G.; Koblitz, B.; Kolya, S.D.; Korbel, V.; Kostka, P.; Kotelnikov, S.K.; Krasny, M.W.; Krehbiel, H.; Kroseberg, J.; Kruger, K.; Kupper, A.; Kuhr, T.; Kurca, T.; Kutuev, R.; Lachnit, W.; Lahmann, R.; Lamb, D.; Landon, M.P.J.; Lange, W.; Lastovicka, T.; Lebailly, E.; Lebedev, A.; Leissner, B.; Lemrani, R.; Lendermann, V.; Levonian, S.; Lindstroem, M.; Lobodzinska, E.; Lobodzinski, B.; Loktionova, N.; Lubimov, V.; Luders, S.; Luke, D.; Lytkin, L.; Magnussen, N.; Mahlke-Kruger, H.; Malden, N.; Malinovski, E.; Malinovski, I.; Maracek, R.; Marage, P.; Marks, J.; Marshall, R.; Martyn, H.U.; Martyniak, J.; Maxfield, S.J.; Mehta, A.; Meier, K.; Merkel, P.; Metlica, F.; Meyer, H.; Meyer, J.; Meyer, P.O.; Mikocki, S.; Milstead, D.; Mkrtchyan, T.; Mohr, R.; Mohrdieck, S.; Mondragon, M.N.; Moreau, F.; Morozov, A.; Morris, J.V.; Muller, K.; Murin, P.; Nagovizin, V.; Naroska, B.; Naumann, J.; Naumann, Th.; Negri, I.; Nellen, G.; Newman, Paul R.; Nicholls, T.C.; Niebergall, F.; Niebuhr, C.; Nix, O.; Nowak, G.; Nunnemann, T.; Olsson, J.E.; Ozerov, D.; Panassik, V.; Pascaud, C.; Patel, G.D.; Perez, E.; Phillips, J.P.; Pitzl, D.; Poschl, R.; Potachnikova, I.; Povh, B.; Rabbertz, K.; Radel, G.; Rauschenberger, J.; Reimer, P.; Reisert, B.; Reyna, D.; Riess, S.; Rizvi, E.; Robmann, P.; Roosen, R.; Rostovtsev, A.; Royon, C.; Rusakov, S.; Rybicki, K.; Sankey, D.P.C.; Scheins, J.; Schilling, F.P.; Schleper, P.; Schmidt, D.; Schmitt, S.; Schoeffel, L.; Schoning, A.; Schorner, T.; Schroder, V.; Schultz-Coulon, H.C.; Sedlak, K.; Sefkow, F.; Chekelian, V.; Sheviakov, I.; Shtarkov, L.N.; Siegmon, G.; Sievers, P.; Sirois, Y.; Sloan, T.; Smirnov, P.; Solochenko, V.; Solovev, Y.; Spaskov, V.; Specka, Arnd E.; Spitzer, H.; Stamen, R.; Steinhart, J.; Stella, B.; Stellberger, A.; Stiewe, J.; Straumann, U.; Struczinski, W.; Swart, M.; Tasevsky, M.; Tchernyshov, V.; Tchetchelnitski, S.; Thompson, Graham; Thompson, P.D.; Tobien, N.; Traynor, D.; Truoel, Peter; Tsipolitis, G.; Turnau, J.; Turney, J.E.; Tzamariudaki, E.; Udluft, S.; Usik, A.; Valkar, S.; Valkarova, A.; Vallee, C.; Van Mechelen, P.; Vazdik, Y.; von Dombrowski, S.; Wacker, K.; Wallny, R.; Walter, T.; Waugh, B.; Weber, G.; Weber, M.; Wegener, D.; Wegner, A.; Wengler, T.; Werner, M.; White, G.; Wiesand, S.; Wilksen, T.; Winde, M.; Winter, G.G.; Wissing, C.; Wobisch, M.; Wollatz, H.; Wunsch, E.; Wyatt, A.C.; Zacek, J.; Zalesak, J.; Zhang, Z.; Zhokin, A.; Zomer, F.; Zsembery, J.; zur Nedden, M.

    2000-01-01

    A search for excited fermions f^* of the first generation in e^+p scattering at the collider HERA is presented using H1 data with an integrated luminosity of 37 pb^(-1). All electroweak decays of excited fermions, f^* -> f gamma, f W, f Z are considered and all possible final states resulting from the Z or W hadronic decays or decays into leptons of the first two generations are taken into account. No evidence for f^* production is found. Mass dependent exclusion limits on cross-sections and on the ratio of coupling constants to the compositeness scale are derived.

  16. Dissociative Excitation of Adenine by Electron Impact

    Science.gov (United States)

    McConkey, J. William; Trocchi, Joshuah; Dech, Jeffery; Kedzierski, Wladek

    2017-04-01

    Dissociative excitation of adenine (C6H5NH2) into excited atomic fragments has been studied in the electron impact energy range from threshold to 300 eV. A crossed beam system coupled to a vacuum ultraviolet (VUV) monochromator is used to study emissions in the wavelength range from 110 to 200 nm. The beam of adenine vapor from a stainless steel oven is crossed at right angles by the electron beam and the resultant UV radiation is detected in a mutually orthogonal direction. The strongest feature in the spectrum is H Lyman- α. Financial support from NSERC and CFI, Canada, is gratefully acknowledged.

  17. Search for Excited Neutrinos at HERA

    CERN Document Server

    Adloff, C.; Andrieu, B.; Anthonis, T.; Arkadov, V.; Astvatsatourov, A.; Babaev, A.; Bahr, J.; Baranov, P.; Barrelet, E.; Bartel, W.; Bate, P.; Becker, J.; Beglarian, A.; Behnke, O.; Beier, C.; Belousov, A.; Benisch, T.; Berger, C.; Berndt, T.; Bizot, J.C.; Boehme, J.; Boudry, V.; Braunschweig, W.; Brisson, V.; Broker, H.B.; Brown, D.P.; Bruckner, W.; Bruncko, D.; Burger, J.; Busser, F.W.; Bunyatyan, A.; Burrage, A.; Buschhorn, G.; Bystritskaya, L.; Campbell, A.J.; Cao, Jun; Caron, S.; Cassol-Brunner, F.; Clarke, D.; Clerbaux, B.; Collard, C.; Contreras, J.G.; Coppens, Y.R.; Coughlan, J.A.; Cousinou, M.C.; Cox, B.E.; Cozzika, G.; Cvach, J.; Dainton, J.B.; Dau, W.D.; Daum, K.; Davidsson, M.; Delcourt, B.; Delerue, N.; Demirchyan, R.; De Roeck, A.; De Wolf, E.A.; Diaconu, C.; Dingfelder, J.; Dixon, P.; Dodonov, V.; Dowell, J.D.; Droutskoi, A.; Dubak, A.; Duprel, C.; Eckerlin, Guenter; Eckstein, D.; Efremenko, V.; Egli, S.; Eichler, R.; Eisele, F.; Eisenhandler, E.; Ellerbrock, M.; Elsen, E.; Erdmann, M.; Erdmann, W.; Faulkner, P.J.W.; Favart, L.; Fedotov, A.; Felst, R.; Ferencei, J.; Ferron, S.; Fleischer, M.; Fleming, Y.H.; Flugge, G.; Fomenko, A.; Foresti, I.; Formanek, J.; Franke, G.; Gabathuler, E.; Gabathuler, K.; Garvey, J.; Gassner, J.; Gayler, Joerg; Gerhards, R.; Gerlich, C.; Ghazaryan, Samvel; Goerlich, L.; Gogitidze, N.; Goldberg, M.; Grab, C.; Grassler, H.; Greenshaw, T.; Grindhammer, Guenter; Hadig, T.; Haidt, D.; Hajduk, L.; Haller, J.; Haynes, W.J.; Heinemann, B.; Heinzelmann, G.; Henderson, R.C.W.; Hengstmann, S.; Henschel, H.; Heremans, R.; Herrera, G.; Herynek, I.; Hildebrandt, M.; Hilgers, M.; Hiller, K.H.; Hladky, J.; Hoting, P.; Hoffmann, D.; Horisberger, R.; Hurling, S.; Ibbotson, M.; Issever, C.; Jacquet, M.; Jaffre, M.; Janauschek, L.; Janssen, X.; Jemanov, V.; Jonsson, L.; Johnson, C.; Johnson, D.P.; Jones, M.A.S.; Jung, H.; Kant, D.; Kapichine, M.; Karlsson, M.; Karschnick, O.; Keil, F.; Keller, N.; Kennedy, J.; Kenyon, I.R.; Kermiche, S.; Kiesling, Christian M.; Kjellberg, P.; Klein, M.; Kleinwort, C.; Kluge, T.; Knies, G.; Koblitz, B.; Kolya, S.D.; Korbel, V.; Kostka, P.; Kotelnikov, S.K.; Koutouev, R.; Koutov, A.; Krehbiel, H.; Kroseberg, J.; Kruger, K.; Kupper, A.; Kuhr, T.; Kurca, T.; Lahmann, R.; Lamb, D.; Landon, M.P.J.; Lange, W.; Lastovicka, T.; Laycock, P.; Lebailly, E.; Lebedev, A.; Leissner, B.; Lemrani, R.; Lendermann, V.; Levonian, S.; Lindstroem, M.; List, B.; Lobodzinska, E.; Lobodzinski, B.; Loginov, A.; Loktionova, N.; Lubimov, V.; Luders, S.; Luke, D.; Lytkin, L.; Mahlke-Kruger, H.; Malden, N.; Malinovski, E.; Malinovski, I.; Maracek, R.; Marage, P.; Marks, J.; Marshall, R.; Martyn, H.U.; Martyniak, J.; Maxfield, S.J.; Meer, D.; Mehta, A.; Meier, K.; Meyer, A.B.; Meyer, H.; Meyer, J.; Meyer, P.O.; Mikocki, S.; Milstead, D.; Mkrtchyan, T.; Mohr, R.; Mohrdieck, S.; Mondragon, M.N.; Moreau, F.; Morozov, A.; Morris, J.V.; Muller, K.; Murin, P.; Nagovizin, V.; Naroska, B.; Naumann, J.; Naumann, T.; Nellen, G.; Newman, Paul R.; Nicholls, T.C.; Niebergall, F.; Niebuhr, C.; Nix, O.; Nowak, G.; Olsson, J.E.; Ozerov, D.; Panassik, V.; Pascaud, C.; Patel, G.D.; Peez, M.; Perez, E.; Phillips, J.P.; Pitzl, D.; Poschl, R.; Potachnikova, I.; Povh, B.; Rabbertz, K.; Radel, G.; Rauschenberger, J.; Reimer, P.; Reisert, B.; Reyna, D.; Risler, C.; Rizvi, E.; Robmann, P.; Roosen, R.; Rostovtsev, A.; Rusakov, S.; Rybicki, K.; Sankey, D.P.C.; Scheins, J.; Schilling, F.P.; Schleper, P.; Schmidt, D.; Schmidt, S.; Schmitt, S.; Schneider, M.; Schoeffel, L.; Schoning, A.; Schorner, T.; Schroder, V.; Schultz-Coulon, H.C.; Schwanenberger, C.; Sedlak, K.; Sefkow, F.; Chekelian, V.; Sheviakov, I.; Shtarkov, L.N.; Sirois, Y.; Sloan, T.; Smirnov, P.; Soloviev, Y.; South, D.; Spaskov, V.; Specka, Arnd E.; Spitzer, H.; Stamen, R.; Stella, B.; Stiewe, J.; Straumann, U.; Swart, M.; Tasevsky, M.; Chernyshov, V.; Chetchelnitski, S.; Thompson, Graham; Thompson, P.D.; Tobien, N.; Traynor, D.; Truoel, Peter; Tsipolitis, G.; Tsurin, I.; Turnau, J.; Turney, J.E.; Tzamariudaki, E.; Udluft, S.; Urban, Marcel; Usik, A.; Valkar, S.; Valkarova, A.; Vallee, C.; Van Mechelen, P.; Vassiliev, S.; Vazdik, Y.; Vichnevski, A.; Wacker, K.; Wallny, R.; Waugh, B.; Weber, G.; Weber, M.; Wegener, D.; Werner, C.; Werner, M.; Werner, N.; White, G.; Wiesand, S.; Wilksen, T.; Winde, M.; Winter, G.G.; Wissing, C.; Wobisch, M.; Woehrling, E.E.; Wunsch, E.; Wyatt, A.C.; Zacek, J.; Zalesak, J.; Zhang, Z.; Zhokin, A.; Zomer, F.; Zsembery, J.; zur Nedden, M.

    2002-01-01

    We present a search for excited neutrinos using e^-p data taken by the H1 experiment at HERA at a center-of-mass energy of 318 GeV with an integrated luminosity of 15 pb-1. No evidence for excited neutrino production is found. Mass dependent exclusion limits are determined for the ratio of the coupling to the compositeness scale, f/Lambda, independently of the relative couplings to the SU(2) and U(1) gauge bosons. These limits extend the excluded region to higher masses than has been possible in previous searches at other colliders.

  18. Low-frequency excitations in zirconium hydrides

    International Nuclear Information System (INIS)

    Radulescu, A.; Padureanu, I.; Rapeanu, S.N.; Beldiman, A.; Kozlov, Zh.A.; Semenov, V.A.

    1999-01-01

    The slow inelastic neutron scattering (INS) on ZrH x systems (x = 0.38, 0.52) revealed new excitations located within the energy range 2-10 MeV. Besides the acoustic vibrations specific to α-HCP Zr and γ-FCO Zr hydride the fine structure of these excitations is clearly observed. The origin of the new observed peaks is not very clear but a proton tunneling or a resonance effect in α-Zr lattice could be taken into account

  19. Microwave spectroscopy of HCOO13CH3 in the second methyl torsional excited state

    Science.gov (United States)

    Kobayashi, Kaori; Kuwahara, Takuro; Tachi, Haruka; Urata, Yuki; Tsunekawa, Shozo; Hayashi, Naoto; Higuchi, Hiroyuki; Fujitake, Masaharu; Ohashi, Nobukimi

    2018-01-01

    The new experimental results and analysis of the microwave spectra of HCOO13CH3 in the second methyl torsional excited state are reported. Pseudo-principal axis method (pseudo-PAM) was successfully applied to the normal methyl formate in the second torsional excited state and again applied to this isotopologue. We succeeded to assign 536 A-species transitions up to J = 33 and Ka = 15 and 417 E-species transitions up to J = 32 and Ka = 14. Thirty parameters were used to do the least-squares-analysis by using the pseudo-PAM Hamiltonian consisting of rotational, centrifugal distortion, and internal-rotational constants.

  20. Work locus of control: the intrinsic factor behind empowerment and work excitement.

    Science.gov (United States)

    Erbin-Roesemann, M A; Simms, L M

    1997-01-01

    A positive focus on empowerment explores the relationship between locus of control, work excitement, and receptivity to new information. Concepts related to control, mastery, and stress management are explored as they relate to an individual's affinity for generative learning, as opposed to adaptive learning. Internally oriented, proactive individuals perceive their jobs to be more enriched and intrinsically motivating than externally oriented, reactive individuals who report low levels of job satisfaction and higher levels of perceived powerlessness. Those whose jobs are being changed should be offered active participation in those redesign efforts. Internally oriented individuals will be more likely to volunteer, and thus to both seek and share information. Participation in such change efforts will enhance perceptions of control and offer the best chances for job satisfaction and successful redesign outcomes, including sustained work excitement among internally motivated employees.

  1. Relative excitation functions for singly-excited and core-excited levels of S V--S IX populated by the beam-foil interaction

    International Nuclear Information System (INIS)

    Moenke, D.; Bengtsson, P.; Engstroem, L.; Hutton, R.; Jupen, C.; Kirm, M.; Westerlind, M.

    1994-01-01

    We have investigated the relative excitation functions for low-lying singly excited and low-lying core-excited levels in S V (S 4+ ) to S IX (S 8+ ) after beam-foil excitation using ions in the energy range 2--10 MeV. The spectral line intensities have been normalized to the same number of particles at each ion energy and corrections for the level lifetimes have been made. The overall accuracy of the measured relative excitation function at each energy and charge state is estimated to be better than 2%. A comparison of the relative excitation functions for singly excited and core-excited lines shows a difference in S VII, but not in S VI

  2. Flow induced vibrational excitation of nuclear reactor structures

    International Nuclear Information System (INIS)

    Gibert, R.J.

    1979-01-01

    The pressure fluctuations generated by disturbed flows, encountered in nuclear reactors induce vibrations in the structures. In order to make forecastings for these vibrational levels, it is necessary to know the characteristics of the random pressure fluctuations induced in the walls by the main flow peculiarities of the circuits. This knowledge is essentially provided by experimentation which shows that most of the energy from these fluctuations is in the low frequency area. It is also necessary to determine the transfer functions of the fluid-structure coupled system. Given the frequency range of the excitations, a calculation of the characteristics of the first eigenmodes is generally sufficient. This calculation is carried out by finite element codes, the modal dampings being assessed separately. In this paper, emphasis is placed mainly on the analysis of the sources of excitation due to flow peculiarities. Some examples will also be given of assessments of vibrations in real structures (pipes, reactor internals, etc.) and of comparisons with the experimental results obtained on models or on a site [fr

  3. Electron impact excitation and ionization of laser-excited sodium atoms Na*(7d)

    International Nuclear Information System (INIS)

    Nienhaus, J.; Dorn, A.; Mehlhorn, W.; Zatsarinny, O.I.

    1997-01-01

    We have investigated the ejected-electron spectrum following impact excitation and ionization of laser-excited Na * (nl) atoms by 1.5 keV electrons. By means of two-laser excitation 3s → 3p 3/2 → 7d and subsequent cascading transitions about 8% (4%) of the target atoms were in excited states with n > 3 (7d). The experimental ejected-electron spectrum due to the decay of Auger and autoionization states of laser-excited atoms Na * (nl) with n = 4-7 has been fully interpreted by comprehensive calculations of the energies, cross sections and decay probabilities of the corresponding states. The various processes contributing to the ejected-electron spectrum are with decreasing magnitude: 2s ionization leading to 2s2p 6 nl Auger states, 2p → 3s excitation leading to 2p 5 3s( 1 P)nl autoionization states and 2s → 3l' excitation leading to 2s2p 6 3l'( 1 L)nl autoionization states. (Author)

  4. Laser pulses for coherent xuv Raman excitation

    Science.gov (United States)

    Greenman, Loren; Koch, Christiane P.; Whaley, K. Birgitta

    2015-07-01

    We combine multichannel electronic structure theory with quantum optimal control to derive femtosecond-time-scale Raman pulse sequences that coherently populate a valence excited state. For a neon atom, Raman target populations of up to 13% are obtained. Superpositions of the ground and valence Raman states with a controllable relative phase are found to be reachable with up to 4.5% population and arbitrary phase control facilitated by the pump pulse carrier-envelope phase. Analysis of the optimized pulse structure reveals a sequential mechanism in which the valence excitation is reached via a fast (femtosecond) population transfer through an intermediate resonance state in the continuum rather than avoiding intermediate-state population with simultaneous or counterintuitive (stimulated Raman adiabatic passage) pulse sequences. Our results open a route to coupling valence excitations and core-hole excitations in molecules and aggregates that locally address specific atoms and represent an initial step towards realization of multidimensional spectroscopy in the xuv and x-ray regimes.

  5. Pion absorption in excited nuclear matter

    International Nuclear Information System (INIS)

    Schmidt, H.R.; Albrecht, R.; Bock, R.; Gutbrod, H.H.; Kolb, B.W.; Lund, I.; Awes, T.C.; Baktash, C.; Ferguson, R.L.; Lee, I.Y.; Plasil, F.; Saini, S.; Tincknell, M.; Young, G.R.; Beckmann, P.; Berger, F.; Clewing, G.; Dragon, L.; Glasow, R.; Kampert, K.H.; Peitzmann, T.; Purschke, M.; Santo, R.; Claesson, G.; Eklund, A.; Garpman, S.; Gustafsson, H.A.; Idh, J.; Oskarsson, A.; Otterlund, I.; Persson, S.; Stenlund, E.; Franz, A.; Jacobs, P.; Poskanzer, A.M.; Ritter, H.G.; Kristiansson, P.; Loehner, H.; Obenshain, F.E.; Sorensen, S.P.; Siemiarczuk, T.

    1992-02-01

    The target dependence and azimuthal correlations of protons and plons are investigated for pA reactions at 4.9, 60 and 200 GeV. The experimental observations can be understood qualitatively under the assumption that pions are absorbed in excited target spectator matter. (orig.)

  6. Effects of noise in excitable systems

    International Nuclear Information System (INIS)

    Lindner, B.; Garcia-Ojalvo, J.; Neiman, A.; Schimansky-Geier, L.

    2004-01-01

    We review the behavior of theoretical models of excitable systems driven by Gaussian white noise. We focus mainly on those general properties of such systems that are due to noise, and present several applications of our findings in biophysics and lasers. As prototypes of excitable stochastic dynamics we consider the FitzHugh-Nagumo and the leaky integrate-and-fire model, as well as cellular automata and phase models. In these systems, taken as individual units or as networks of globally or locally coupled elements, we study various phenomena due to noise, such as noise-induced oscillations, stochastic resonance, stochastic synchronization, noise-induced phase transitions and noise-induced pulse and spiral dynamics. Our approach is based on stochastic differential equations and their corresponding Fokker-Planck equations, treated by both analytical calculations and/or numerical simulations. We calculate and/or measure the rate and diffusion coefficient of the excitation process, as well as spectral quantities like power spectra and degree of coherence. Combined with a multiparametric bifurcation analysis of the corresponding cumulant equations, these approaches provide a comprehensive picture of the multifaceted dynamical behaviour of noisy excitable systems

  7. Favored neutron excitations in superdeformed Gd-147

    NARCIS (Netherlands)

    Theisen, C; Khadiri, N; Vivien, JP; Ragnarsson, J; Beausang, CW; Beck, FA; Belier, G; Byrski, T; Curien, D; deFrance, G; Disdier, D; Duchene, G; Finck, C; Flibotte, S; Gall, B; Haas, B; Hanine, H; Herskind, B; Kharraja, B; Merdinger, JC; Nourreddine, A; Nyako, BM; Perez, GE; Prevost, D; Stezowski, O; Rauch, I; Rigollet, C; Savajols, H; SharpeySchafer, J; Twin, PJ; Wei, L; Zuber, K

    1996-01-01

    Four new superdeformed (SD) bands have been observed in Gd-147 using the EUROGAM II spectrometer. By comparison with (146,148,149),Gd SD bands, we use the effective alignment to assign excited band configurations, with the support of the Nilsson-Strutinsky cranking formalism. The effect of the

  8. Global chaos synchronization of coupled parametrically excited ...

    Indian Academy of Sciences (India)

    In this paper, we study the synchronization behaviour of two linearly coupled parametrically excited chaotic pendula. The stability of the synchronized state is examined using Lyapunov stability theory and linear matrix inequality (LMI); and some sufficient criteria for global asymptotic synchronization are derived from which ...

  9. The Mean Excitation Energy of Atomic Ions

    DEFF Research Database (Denmark)

    Sauer, Stephan; Oddershede, Jens; Sabin, John R.

    2015-01-01

    A method for calculation of the mean excitation energies of atomic ions is presented, making the calculation of the energy deposition of fast ions to plasmas, warm, dense matter, and complex biological systems possible. Results are reported to all ions of helium, lithium, carbon, neon, aluminum...

  10. Multipurpose exciter with low phase noise

    Science.gov (United States)

    Conroy, B.; Le, D.

    1989-01-01

    Results of an effort to develop a lower-cost exciter with high stability, low phase noise, and controllable phase and frequency for use in Deep Space Network and Goldstone Solar System Radar applications are discussed. Included is a discussion of the basic concept, test results, plans, and concerns.

  11. Fluorescent excitation of interstellar H2

    NARCIS (Netherlands)

    Black, J.H.; Dishoeck, van E.F.

    1987-01-01

    The infrared emission spectrum of H2 excited by ultraviolet absorption, followed by fluorescence, was investigated using comprehensive models of interstellar clouds for computing the spectrum and to assess the effects on the intensity to various cloud properties, such as density, size, temperature,

  12. Electronic excitation in ion-atom collisions

    International Nuclear Information System (INIS)

    Rodriguez, V.D.; Miraglia, J.E.

    1988-01-01

    Theoretical calculations for excitation of hydrogen-like atoms by ion impact at high and intermediate energies, are presented. Impulsive and eikonal wave functions are employed, both normalized. It is studied the dependence on energy and projectil charge (saturation) of cross sections, compared to experimental results. (A.C.A.S.) [pt

  13. Strange diquarks and orbital excitations of hyperons

    International Nuclear Information System (INIS)

    Kondratyuk, L.A.; Ralchenko, Yu.V.; Vasilets, A.V.

    1987-01-01

    Using the model of the QCD string with spin-orbital interaction the masses of strange diquarks are determined. The spectra of orbital excitations of the Λ and Σ hyperons are calculated and discussed. Also the decay modes for Λ's and Σ's are considered

  14. Does intrinsic motivation enhance motor cortex excitability?

    Science.gov (United States)

    Radel, Rémi; Pjevac, Dusan; Davranche, Karen; d'Arripe-Longueville, Fabienne; Colson, Serge S; Lapole, Thomas; Gruet, Mathieu

    2016-11-01

    Intrinsic motivation (IM) is often viewed as a spontaneous tendency for action. Recent behavioral and neuroimaging evidence indicate that IM, in comparison to extrinsic motivation (EM), solicits the motor system. Accordingly, we tested whether IM leads to greater excitability of the motor cortex than EM. To test this hypothesis, we used two different tasks to induce the motivational orientation using either words representing each motivational orientation or pictures previously linked to each motivational orientation through associative learning. Single-pulse transcranial magnetic stimulation over the motor cortex was applied when viewing the stimuli. Electromyographic activity was recorded on the contracted first dorsal interosseous muscle. Two indexes of corticospinal excitability (the amplitude of motor-evoked potential and the length of cortical silent period) were obtained through unbiased automatic detection and analyzed using a mixed model that provided both statistical power and a high level of control over all important individual, task, and stimuli characteristics. Across the two tasks and the two indices of corticospinal excitability, the exposure to IM-related stimuli did not lead to a greater corticospinal excitability than EM-related stimuli or than stimuli with no motivational valence (ps > .20). While these results tend to dismiss the advantage of IM at activating the motor cortex, we suggest alternative hypotheses to explain this lack of effect, which deserves further research. © 2016 Society for Psychophysiological Research.

  15. Development of longitudinally excited CO2 laser

    Science.gov (United States)

    Masroon, N. S.; Tanaka, M.; Tei, M.; Uno, K.; Tsuyama, M.; Nakano, H.

    2018-05-01

    Simple, compact, and affordable discharged-pumped CO2 laser controlled by a fast high voltage solid state switch has been developed. In this study, longitudinal excitation scheme has been adapted for simple configuration. In the longitudinal excitation scheme, the discharge is produced along the direction of the laser axis, and the electrodes are well separated with a small discharge cross-section. Triggered spark gap switch is usually used to switch out the high voltage because of simple and low cost. However, the triggered spark gap operates in the arc mode and suffer from recovery problem causing a short life time and low efficiency for high repetition rate operation. As a result, there is now considerable interest in replacing triggered spark gap switch with solid state switches. Solid state switches have significant advantages compared to triggered spark gap switch which include longer service lifetime, low cost and stable high trigger pulse. We have developed simple and low cost fast high voltage solid state switch that consists of series connected-MOSFETs. It has been installed to the longitudinally excited CO2 laser to realize the gap switch less operation. Characteristics of laser oscillation by varying the discharge length, charging voltage, capacitance and gas pressure have been evaluated. Longer discharge length produce high power of laser oscillation. Optimum charging voltage and gas pressure were existed for longitudinally excited CO2 laser.

  16. An analytical excitation for an ionizing plasma

    NARCIS (Netherlands)

    Mullen, van der J.J.A.M.; Sijde, van der B.; Schram, D.C.

    1983-01-01

    From an analytical model for the population of high-lying excited levels in ionizing plasmas it appears that the distribution is a superposition of the equilibrium (Saha) value and an overpopulation. This overpopulation takes the form of a Maxwell distribution for free electrons. Experiments for He

  17. Excited species in the FBX dosimeter system

    International Nuclear Information System (INIS)

    Gupta, B.L.

    2003-01-01

    In the FBX dosimeter solution, the excitation of xylenol orange (XO) produces maximum emission at 550-575 nm both at room and liquid nitrogen temperatures (about 85%) having a lifetime of 0.20-0.36 ns. In addition, at room temperature there is an emission at 350 nm for the excitation at 260 nm (about 15%) having a longer lifetime of 3.71-4.01 ns. Benzoic acid (BA) has excitation at 284-295 nm and emission at 320-365 nm having a lifetime of 1.38 ns. In an aqueous solution containing 5x10 -3 mol dm -3 BA, 2x10 -4 mol dm -3 XO and 0.04 mol dm -3 H 2 SO 4 there is no XO emission at 550 nm due to UV absorption at 260 nm by BA. In this solution, 2 emissions are observed near 350-360 nm, having lifetimes of 1.25 ns (89%) and 2.86 ns (11%). The wavelengths for the emission of XO and absorption of ferric-XO complex are nearly the same. Excited XO produces oxidation of ferrous ions and BA increases the chain length

  18. Nuclear excitations in the nuclear response theory

    International Nuclear Information System (INIS)

    Nguyen Van Giai.

    1983-01-01

    The Random Phase Approximation is used to calculate the response of a nucleus to an external field. The method allows a full treatment of continuum effects. Effective interactions to be used are discussed, and the consistency between the mean field and the residual interaction is stressed. Some applications to excitation properties of spherical nuclei are shown

  19. Collective Quadrupole Excitations of Transactinide Nuclei

    CERN Document Server

    Zajac, K; Pomorski, K; Rohozinski, S G; Srebrny, J

    2003-01-01

    The quadrupole excitations of transuranic nuclei are described in the frame of the microscopic Bohr Hamiltonian modified by adding the coupling with the collective pairing vibrations. The energies of the states from the ground-state bands in U to No even-even isotopes as well as the B(E2) transition probabilities are reproduced within the model containing no adjustable parameters.

  20. Coherent acoustic excitation of cavity polaritons

    DEFF Research Database (Denmark)

    Poel, Mike van der; de Lima, M. M.; Hey, R.

    The study of acoustic excitation of semiconductor based photonic structures is anemerging field with great potential for new types of photonic manipulation1. In this paperwe present results of using a surface acoustic wave (SAW) to modulate a microcavitywith embedded quantum-well (QW) active layer...

  1. Giant dipole resonances built on excited states

    International Nuclear Information System (INIS)

    Snover, K.A.

    1983-01-01

    The properties of giant dipole resonances built on excited nuclear states are reviewed, with emphasis on recent results. Nonstatistical (p,γ) reactions in light nuclei, and statistical complex-particle reactions in light and heavy nuclei are discussed. 27 references

  2. Excitation spectrum of Heisenberg spin ladders

    International Nuclear Information System (INIS)

    Barnes, T.; Dagotto, E.; Riera, J.; Swanson, E.S.

    1993-01-01

    Heisenberg antiferromagnetic spin ''ladders'' (two coupled spin chains) are low-dimensional magnetic systems which for S=1/2 interpolate between half-integer-spin chains, when the chains are decoupled, and effective integer-spin one-dimensional chains in the strong-coupling limit. The spin-1/2 ladder may be realized in nature by vanadyl pyrophosphate, (VO) 2 P 2 O 7 . In this paper we apply strong-coupling perturbation theory, spin-wave theory, Lanczos techniques, and a Monte Carlo method to determine the ground-state energy and the low-lying excitation spectrum of the ladder. We find evidence of a nonzero spin gap for all interchain couplings J perpendicular >0. A band of spin-triplet excitations above the gap is also analyzed. These excitations are unusual for an antiferromagnet, since their long-wavelength dispersion relation behaves as (k-k 0 ) 2 (in the strong-coupling limit J perpendicular much-gt J, where J is the in-chain antiferromagnetic coupling). Their band is folded, with a minimum energy at k 0 =π, and a maximum between k 1 =π/2 (for J perpendicular =0) and 0 (for J perpendicular =∞). We also give numerical results for the dynamical structure factor S(q,ω), which can be determined in neutron scattering experiments. Finally, possible experimental techniques for studying the excitation spectrum are discussed

  3. Collective excitations of harmonically trapped ideal gases

    NARCIS (Netherlands)

    Van Schaeybroeck, B.; Lazarides, A.

    2009-01-01

    We theoretically study the collective excitations of an ideal gas confined in an isotropic harmonic trap. We give an exact solution to the Boltzmann-Vlasov equation; as expected for a single-component system, the associated mode frequencies are integer multiples of the trapping frequency. We show

  4. Creation of skyrmion through resonance excitation

    Energy Technology Data Exchange (ETDEWEB)

    Li, Zhi-xiong; Chen, Yi-fu; Zhou, Zhen-wei; Nie, Yao-zhuang; Xia, Qing-lin; Wang, Dao-wei; Guo, Guang-hua, E-mail: guogh@mail.csu.edu.cn

    2017-07-01

    Highlights: • Intrinsic oscillation modes of skyrmion are studied by using micromagnetic simulation. • Creation of skyrmion through resonant excitation is proposed. • The number of generated skyrmions can be effectively controlled by manipulating the driving field. • Skyrmion lattice in extended film is generated via resonant excitation. - Abstract: Controllable creation of magnetic skyrmions in nanostructures is a prerequisite for the application of skyrmions in spintronics. Here, we propose a new method for the creation of skyrmions. We show by using micromagnetic simulations that the skyrmions can be nucleated by resonantly exciting one of the skyrmion intrinsic oscillation modes. We first studied the dynamics of skyrmion in a ferromagnetic nanodisk with perpendicular anisotropy. One breathing mode and two non-degenerate gyrotropic modes are identified. Then we applied a circular-polarized microwave field to excite the uniformly magnetized nanodisk. When the frequency of the driving field is equal to the eigenfrequency of the skyrmion gyrotropic mode, stable skyrmions can be created from the initial uniform state. The number of skyrmions can be effectively controlled by appropriately choosing the duration of the driving field or tuning the field amplitude.

  5. Topics in magnetism: magnetic excitations in insulators

    International Nuclear Information System (INIS)

    Rezende, S.M.

    1975-01-01

    The concept of spin waves is introduced and green's functions formalism is used in connection with thermodynamic properties of ferromagnets. Simple features of magnons in ferromagnetic insulators are discussed and also of those with dipolar and anisotropic contributions in the hamiltonian. Magnons in more complex systems, e.g. antiferromagnetic crystals, are dealt with. Finally, excitation and detection of magnons are also discussed [pt

  6. Structure of wobbling excitations in 163Lu

    International Nuclear Information System (INIS)

    Carlsson, B.G.

    2007-01-01

    Using a many-particles plus rotor model, wobbling excitations built on top of a triaxial superdeformed band in 163 Lu are investigated. By extracting all parameters for the rotor from a mean field calculation a good correspondence with calculations based on the random-phase approximation is achieved. (author)

  7. Excited state properties of aryl carotenoids

    Czech Academy of Sciences Publication Activity Database

    Fuciman, M.; Chábera, P.; Župčanová, Anita; Hříbek, P.; Arellano, J.B.; Vácha, František; Pšenčík, J.; Polívka, Tomáš

    2010-01-01

    Roč. 12, č. 13 (2010), s. 3112-3120 ISSN 1463-9076 R&D Projects: GA AV ČR IAA608170604 Institutional research plan: CEZ:AV0Z50510513 Keywords : carotenoids * excited-states * femtosecond spectroscopy Subject RIV: BO - Biophysics Impact factor: 3.454, year: 2010

  8. Collective excitations in deformed alkali metal clusters

    International Nuclear Information System (INIS)

    Lipparini, E.; Stringari, S.; Istituto Nazionale di Fisica Nucleare, Povo

    1991-01-01

    A theoretical study of collective excitations in deformed metal clusters is presented. Sum rules are used to study the splittings of the dipole surface plasma resonance originating from the cluster deformation. The vibrating potential model is developed and used to predict the occurrence of a low lying collective mode of orbital magnetic nature. (orig.)

  9. Baryon excitations in the bag model

    International Nuclear Information System (INIS)

    Jaffe, R.L.

    1976-07-01

    Two recent spectroscopic applications of the bag model are discussed. The first is a study of the place of multiquark states in meson and baryon spectroscopy, and the second is an attempt to sort out the P-wave baryon excitations in a bag model. 33 references

  10. Extended Lagrangian Excited State Molecular Dynamics.

    Science.gov (United States)

    Bjorgaard, J A; Sheppard, D; Tretiak, S; Niklasson, A M N

    2018-02-13

    An extended Lagrangian framework for excited state molecular dynamics (XL-ESMD) using time-dependent self-consistent field theory is proposed. The formulation is a generalization of the extended Lagrangian formulations for ground state Born-Oppenheimer molecular dynamics [Phys. Rev. Lett. 2008 100, 123004]. The theory is implemented, demonstrated, and evaluated using a time-dependent semiempirical model, though it should be generally applicable to ab initio theory. The simulations show enhanced energy stability and a significantly reduced computational cost associated with the iterative solutions of both the ground state and the electronically excited states. Relaxed convergence criteria can therefore be used both for the self-consistent ground state optimization and for the iterative subspace diagonalization of the random phase approximation matrix used to calculate the excited state transitions. The XL-ESMD approach is expected to enable numerically efficient excited state molecular dynamics for such methods as time-dependent Hartree-Fock (TD-HF), Configuration Interactions Singles (CIS), and time-dependent density functional theory (TD-DFT).

  11. Lithium. Effects on excitable cell membranes

    NARCIS (Netherlands)

    Ploeger, Egbert Johan

    1974-01-01

    LITHIUM: Effects on excitable cell membranes. Lithium salts have been used in the treatment of manic-depressive psychosis for many years but their mechanism of action is not well understood. Many workers assume that the action of lithium on catecholamine metabolism and/or on electrolyte distribution

  12. Magnetic excitations in CuO

    International Nuclear Information System (INIS)

    Ain, M.; Reichardt, W.; Hennion, B.; Pepy, G.; Wanklyn, B.M.

    1989-01-01

    The authors have studied the magnetic excitations of CuO both in the ordered and the paramagnetic phase. Their results demonstrate the dominance of the magnetic interaction along the 10-1 Cu-O zigzag chains. In this direction the slope of the acoustic branch is 550 neV Angstrom

  13. Surface excitation parameter for rough surfaces

    International Nuclear Information System (INIS)

    Da, Bo; Salma, Khanam; Ji, Hui; Mao, Shifeng; Zhang, Guanghui; Wang, Xiaoping; Ding, Zejun

    2015-01-01

    Graphical abstract: - Highlights: • Instead of providing a general mathematical model of roughness, we directly use a finite element triangle mesh method to build a fully 3D rough surface from the practical sample. • The surface plasmon excitation can be introduced to the realistic sample surface by dielectric response theory and finite element method. • We found that SEP calculated based on ideal plane surface model are still reliable for real sample surface with common roughness. - Abstract: In order to assess quantitatively the importance of surface excitation effect in surface electron spectroscopy measurement, surface excitation parameter (SEP) has been introduced to describe the surface excitation probability as an average number of surface excitations that electrons can undergo when they move through solid surface either in incoming or outgoing directions. Meanwhile, surface roughness is an inevitable issue in experiments particularly when the sample surface is cleaned with ion beam bombardment. Surface roughness alters not only the electron elastic peak intensity but also the surface excitation intensity. However, almost all of the popular theoretical models for determining SEP are based on ideal plane surface approximation. In order to figure out whether this approximation is efficient or not for SEP calculation and the scope of this assumption, we proposed a new way to determine the SEP for a rough surface by a Monte Carlo simulation of electron scattering process near to a realistic rough surface, which is modeled by a finite element analysis method according to AFM image. The elastic peak intensity is calculated for different electron incident and emission angles. Assuming surface excitations obey the Poisson distribution the SEPs corrected for surface roughness are then obtained by analyzing the elastic peak intensity for several materials and for different incident and emission angles. It is found that the surface roughness only plays an

  14. Electric quadrupole excitation of the first excited state of 11B

    International Nuclear Information System (INIS)

    Fewell, M.P.; Spear, R.H.; Zabel, T.H.; Baxter, A.M.

    1980-02-01

    The Coulomb excitation of backscattered 11 B projectiles has been used to measure the reduced E2 transition probability B(E2; 3/2 - →1/2 - ) between the 3/2 - ground state and the 1/2 - first excited state of 11 B. It is found that B(E2; 3/2 - →1/2 - ) = 2.1 +- 0.4 e 2 fm 4 , which agrees with shell-model predictions but is a factor of 10 larger than the prediction of the core-excitation model

  15. Saturated excitation of Fluorescence to quantify excitation enhancement in aperture antennas

    KAUST Repository

    Aouani, Heykel

    2012-07-23

    Fluorescence spectroscopy is widely used to probe the electromagnetic intensity amplification on optical antennas, yet measuring the excitation intensity amplification is a challenge, as the detected fluorescence signal is an intricate combination of excitation and emission. Here, we describe a novel approach to quantify the electromagnetic amplification in aperture antennas by taking advantage of the intrinsic non linear properties of the fluorescence process. Experimental measurements of the fundamental f and second harmonic 2f amplitudes of the fluorescence signal upon excitation modulation are used to quantify the electromagnetic intensity amplification with plasmonic aperture antennas. © 2012 Optical Society of America.

  16. Saturated excitation of Fluorescence to quantify excitation enhancement in aperture antennas

    KAUST Repository

    Aouani, Heykel; Hostein, Richard; Mahboub, Oussama; Devaux, Eloï se; Rigneault, Hervé ; Ebbesen, Thomas W.; Wenger, Jé rô me

    2012-01-01

    Fluorescence spectroscopy is widely used to probe the electromagnetic intensity amplification on optical antennas, yet measuring the excitation intensity amplification is a challenge, as the detected fluorescence signal is an intricate combination of excitation and emission. Here, we describe a novel approach to quantify the electromagnetic amplification in aperture antennas by taking advantage of the intrinsic non linear properties of the fluorescence process. Experimental measurements of the fundamental f and second harmonic 2f amplitudes of the fluorescence signal upon excitation modulation are used to quantify the electromagnetic intensity amplification with plasmonic aperture antennas. © 2012 Optical Society of America.

  17. Composite model describing the excitation and de-excitation of nitrogen by an electron beam

    International Nuclear Information System (INIS)

    Kassem, A.E.; Hickman, R.S.

    1975-01-01

    Based on recent studies, the effect of re-excited ions in the emission of electron beam induced fluorescence in nitrogen has been estimated. These effects are included in the formulation of a composite model describing the excitation and de-excitation of nitrogen by an electron beam. The shortcomings of previous models, namely the dependence of the measured temperature on true gas temperature as well as the gas density, are almost completely eliminated in the range of temperatures and densities covered by the available data. (auth)

  18. Energy dependence of the ionization of highly excited atoms by collisions with excited atoms

    International Nuclear Information System (INIS)

    Shirai, T.; Nakai, Y.; Nakamura, H.

    1979-01-01

    Approximate analytical expressions are derived for the ionization cross sections in the high- and low-collision-energy limits using the improved impulse approximation based on the assumption that the electron-atom inelastic-scattering amplitude is a function only of the momentum transfer. Both cases of simultaneous excitation and de-excitation of one of the atoms are discussed. The formulas are applied to the collisions between two excited hydrogen atoms and are found very useful for estimating the cross sections in the wide range of collisions energies

  19. Self-excitation of single nanomechanical pillars

    Science.gov (United States)

    Kim, Hyun S.; Qin, Hua; Blick, Robert H.

    2010-03-01

    Self-excitation is a mechanism that is ubiquitous for electromechanical power devices such as electrical generators. This is conventionally achieved by making use of the magnetic field component in electrical generators (Nedic and Lipo 2000 IEEE/IAS Conf. Records (Rome, Italy) vol 1 pp 51-6), a good and widely visible example of which is the wind turbine farm (Muljadi et al 2005 J. Sol. Energy Eng. 127 581-7). In other words, a static force, such as the wind acting on rotor blades, can generate a resonant excitation at a certain mechanical frequency. For nanomechanical systems (Craighead 2000 Science 290 1532-5 Roukes 2001 Phys. World 14 25-31 Cleland 2003 Foundations of Nanomechanics (Berlin: Springer); Ayari et al 2007 Nano Lett. 7 2252-7 Koenig et al 2008 Nat. Nanotechnol. 3 482-4) such a self-excitation (SE) mechanism is also highly desirable, because it can generate mechanical oscillations at radio frequencies by simply applying a dc bias voltage. This is of great importance for low-power signal communication devices and detectors, as well as for mechanical computing elements. For a particular nanomechanical system—the single electron shuttle—this effect was predicted some time ago by Gorelik et al (Phys. Rev. Lett. 80 4526-9). Here, we use a nanoelectromechanical single electron transistor (NEMSET) to demonstrate self-excitation for both the soft and hard regimes, respectively. The ability to use self-excitation in nanomechanical systems may enable the detection of quantum mechanical backaction effects (Naik et al 2006 Nature 443 193-6) in direct tunneling, macroscopic quantum tunneling (Savelev et al 2006 New J. Phys. 8 105-15) and rectification (Pistolesi and Fazio 2005 Phys. Rev. Lett. 94 036806-4). All these effects have so far been overshadowed by the large driving voltages that had to be applied.

  20. Coulomb excitation of {sup 8}Li

    Energy Technology Data Exchange (ETDEWEB)

    Assuncao, Marlete; Britos, Tatiane Nassar [Universidade Federal de Sao Paulo (UNIFESP), SP (Brazil). Dept. de Ciencias Exatas e da Terra; Descouvemont, Pierre [Universite Libre de Bruxelles (ULB), Brussels (Belgium). Physique Nucleaire Theorique et Physique Mathematique; Lepine-Szily, Alinka; Lichtenthaler Filho, Rubens; Barioni, Adriana; Silva, Diego Medeiros da; Pereira, Dirceu; Mendes Junior, Djalma Rosa; Pires, Kelly Cristina Cezaretto; Gasques, Leandro Romero; Morais, Maria Carmen; Added, Nemitala; Neto Faria, Pedro; Rec, Rafael [Universidade de Sao Paulo (IF/USP), SP (Brazil). Inst. de Fisica. Dept. de Fisica Nuclear

    2012-07-01

    Full text: This work shows the Coulomb Excitation of {sup 8}Li on targets that have effectively behavior of Rutherford in angles and energies of interest for determining the value of the B(E2) electromagnetic transition. Theoretical aspects involved in this type of measure, known as COULEX [1], and some results in the literature [2-3] will be presented. Some problems with the targets and measurement system while performing an experiment on Coulomb Excitation of {sup 8}Li will be discussed: the energy resolution, background, possible contributions of the primary beam and also the excited states of the target near the region of elastic and inelastic peaks. They will be illustrated by measurements of the Coulomb Excitation of {sup 8}Li on targets of {sup 197}Au and {sup 208}Pb using the system RIBRAS(Brazilian Radioactive Ion Beam). In this case, the {sup 8}Li beam(T{sub 1/2} = 838 ms)is produced by {sup 9}Be({sup 7}Li;{sup 8} Li){sup 8}Be reaction from RIBRAS system which is installed at Instituto de Fisica of the Universidade de Sao Paulo. The primary {sup 7L}i beam is provided by Pelletron Accelerator. [1] K. Alder and A. Winther, Electromagnetic Excitation, North-Holland, New York, 1975; [2] P. Descouvemont and D. Baye, Phys. Letts. B 292, 235-238, 1992; [3] J. A. Brown, F. D. Becchetti, J. W. Jaenecke, K, Ashktorab, and D. A. Roberts, J. J. Kolata, R. J. Smith, and K. Lamkin, R. E. Warner, Phys. Rev. Letts., 66, 19, 1991; [4] R. J. Smith, J. J Kolata, K. Lamkin and A. Morsard, F. D. Becchetti, J. A. Brown, W. Z. Liu, J. W. Jaenecke, and D. A. Roberts, R. E. Warner, Phys. Rev. C, 43, 5, 1991. (author)

  1. Fatigue diminishes motoneuronal excitability during cycling exercise.

    Science.gov (United States)

    Weavil, Joshua C; Sidhu, Simranjit K; Mangum, Tyler S; Richardson, Russell S; Amann, Markus

    2016-10-01

    Exercise-induced fatigue influences the excitability of the motor pathway during single-joint isometric contractions. This study sought to investigate the influence of fatigue on corticospinal excitability during cycling exercise. Eight men performed fatiguing constant-load (80% W peak ; 241 ± 13 W) cycling to exhaustion during which the percent increase in quadriceps electromyography (ΔEMG; vastus lateralis and rectus femoris) was quantified. During a separate trial, subjects performed two brief (∼45 s) nonfatiguing cycling bouts (244 ± 15 and 331 ± 23W) individually chosen to match the ΔEMG across bouts to that observed during fatiguing cycling. Corticospinal excitability during exercise was quantified by transcranial magnetic, electric transmastoid, and femoral nerve stimulation to elicit motor-evoked potentials (MEP), cervicomedullary evoked potentials (CMEP), and M waves in the quadriceps. Peripheral and central fatigue were expressed as pre- to postexercise reductions in quadriceps twitch force (ΔQ tw ) and voluntary quadriceps activation (ΔVA). Whereas nonfatiguing cycling caused no measureable fatigue, fatiguing cycling resulted in significant peripheral (ΔQ tw : 42 ± 6%) and central (ΔVA: 4 ± 1%) fatigue. During nonfatiguing cycling, the area of MEPs and CMEPs, normalized to M waves, similarly increased in the quadriceps (∼40%; P fatiguing cycling. As a consequence, the ratio of MEP to CMEP was unchanged during both trials (P > 0.5). Therefore, although increases in muscle activation promote corticospinal excitability via motoneuronal facilitation during nonfatiguing cycling, this effect is abolished during fatigue. We conclude that the unaltered excitability of the corticospinal pathway from start of intense cycling exercise to exhaustion is, in part, determined by inhibitory influences on spinal motoneurons obscuring the facilitating effects of muscle activation.

  2. Selective serotonergic excitation of callosal projection neurons

    Directory of Open Access Journals (Sweden)

    Daniel eAvesar

    2012-03-01

    Full Text Available Serotonin (5-HT acting as a neurotransmitter in the cerebral cortex is critical for cognitive function, yet how 5-HT regulates information processing in cortical circuits is not well understood. We tested the serotonergic responsiveness of layer 5 pyramidal neurons (L5PNs of the mouse medial prefrontal cortex (mPFC, and found 3 distinct response types: long-lasting 5-HT1A (1A receptor-dependent inhibitory responses (84% of L5PNs, 5-HT2A (2A receptor-dependent excitatory responses (9%, and biphasic responses in which 2A-dependent excitation followed brief inhibition (5%. Relative to 5-HT-inhibited neurons, those excited by 5-HT had physiological properties characteristic of callosal/commissural (COM neurons that project to the contralateral cortex. We tested whether serotonergic responses in cortical pyramidal neurons are correlated with their axonal projection pattern using retrograde fluorescent labeling of COM and corticopontine-projecting (CPn neurons. 5-HT generated excitatory or biphasic responses in all 5-HT-responsive layer 5 COM neurons. Conversely, CPn neurons were universally inhibited by 5-HT. Serotonergic excitation of COM neurons was blocked by the 2A antagonist MDL 11939, while serotonergic inhibition of CPn neurons was blocked by the 1A antagonist WAY 100635, confirming a role for these two receptor subtypes in regulating pyramidal neuron activity. Selective serotonergic excitation of COM neurons was not layer-specific, as COM neurons in layer 2/3 were also selectively excited by 5-HT relative to their non-labeled pyramidal neuron neighbors. Because neocortical 2A receptors are implicated in the etiology and pathophysiology of schizophrenia, we propose that COM neurons may represent a novel cellular target for intervention in psychiatric disease.

  3. Vibrational excitation in a hydrogen volume source

    International Nuclear Information System (INIS)

    Eenshuistra, P.J.

    1989-01-01

    In this thesis the complex of processes which determines the D - or H - density in a volume source, a hydrogen discharge, is studied. D - beams are of interest for driving the current of a fusion plasma in a TOKAMAK. Densities of vibrationally excited molecules, of H atoms, and of metastable hydrogen molecules were determined using Resonance-Enhanced MultiPhoton Ionization (REMPI). An experiment in which vibrationally highly excited molecules are formed by recombination of atoms in a cold metal surface, is described. The production and destruction of vibrationally excited molecules and atoms in the discharge is discussed. The vibrational distribution for 3≤ν≤5 (ν = vibrational quantumnumber) is strongly super-thermal. This effect is more apparent at higher discharge current and lower gas pressure. The analysis with a model based on rate equations, which molecules are predominantly produced by primary electron excitation of hydrogen molecules and deexcited upon one wall collision. The atom production is compatible with dissociation of molecules by primary electrons, dissociation of molecules on the filaments, and collisions between positive ions and electrons. The electrons are predominantly destroyed by recombination on the walls. Finally the production and destruction of H - in the discharge are discussed. The density of H - in the plasma, the electron density and temperature were determined. H - extraction was measured. The ratio of the extracted H - current and the H - density in the plasma gives an indication of the drift velocity of H - in the plasma. This velocity determines the emittance of the extracted beam. It was found that the H - velocity scales with the square root of the electron temperature. The measured H - densities are compatible with a qualitative model in which dissociative attachment of plasma electrons to vibrationally excited molecules is the most important process. (author). 136 refs.; 39 figs.; 10 tabs

  4. Classification of a Supersolid: Trial Wavefunctions, Symmetry Breakings and Excitation Spectra

    Science.gov (United States)

    Chen, Yu; Ye, Jinwu; Tian, Guangshan

    2012-11-01

    A state of matter is characterized by its symmetry breaking and elementary excitations. A supersolid is a state which breaks both translational symmetry and internal U(1) symmetry. Here, we review some past and recent works in phenomenological Ginsburg-Landau theories, ground state trial wavefunctions and microscopic numerical calculations. We also write down a new effective supersolid Hamiltonian on a lattice. The eigenstates of the Hamiltonian contains both the ground state wavefunction and all the excited states (supersolidon) wavefunctions. We contrast various kinds of supersolids in both continuous systems and on lattices, both condensed matter and cold atom systems. We provide additional new insights in studying their order parameters, symmetry breaking patterns, the excitation spectra and detection methods.

  5. Modeling the internal combustion engine

    Science.gov (United States)

    Zeleznik, F. J.; Mcbride, B. J.

    1985-01-01

    A flexible and computationally economical model of the internal combustion engine was developed for use on large digital computer systems. It is based on a system of ordinary differential equations for cylinder-averaged properties. The computer program is capable of multicycle calculations, with some parameters varying from cycle to cycle, and has restart capabilities. It can accommodate a broad spectrum of reactants, permits changes in physical properties, and offers a wide selection of alternative modeling functions without any reprogramming. It readily adapts to the amount of information available in a particular case because the model is in fact a hierarchy of five models. The models range from a simple model requiring only thermodynamic properties to a complex model demanding full combustion kinetics, transport properties, and poppet valve flow characteristics. Among its many features the model includes heat transfer, valve timing, supercharging, motoring, finite burning rates, cycle-to-cycle variations in air-fuel ratio, humid air, residual and recirculated exhaust gas, and full combustion kinetics.

  6. Dissociative Excitation of Acetylene Induced by Electron Impact: Excitation-emission Cross-sections

    Energy Technology Data Exchange (ETDEWEB)

    Országh, Juraj; Danko, Marián; Čechvala, Peter; Matejčík, Štefan, E-mail: matejcik@fmph.uniba.sk [Department of Experimental Physics, Faculty of Mathematics, Physics and Informatics, Comenius University in Bratislava, Mlynská dolina F-2, 842 48 Bratislava (Slovakia)

    2017-05-20

    The optical emission spectrum of acetylene excited by monoenergetic electrons was studied in the range of 190–660 nm. The dissociative excitation and dissociative ionization associated with excitation of the ions initiated by electron impact were dominant processes contributing to the spectrum. The spectrum was dominated by the atomic lines (hydrogen Balmer series, carbon) and molecular bands (CH(A–X), CH(B–X), CH{sup +}(B–A), and C{sub 2}). Besides the discrete transitions, we have detected the continuum emission radiation of ethynyl radical C{sub 2}H(A–X). For most important lines and bands of the spectrum we have measured absolute excitation-emission cross sections and determined the energy thresholds of the particular dissociative channels.

  7. Production of excited double hypernuclei via Fermi breakup of excited strange systems

    International Nuclear Information System (INIS)

    Sanchez Lorente, Alicia; Botvina, Alexander S.; Pochodzalla, Josef

    2011-01-01

    Precise spectroscopy of multi-strange hypernuclei provides a unique chance to explore the hyperon-hyperon interaction. In the present work we explore the production of excited states in double hypernuclei following the micro-canonical break-up of an initially excited double hypernucleus which is created by the absorption and conversion of a stopped Ξ - hyperon. Rather independent on the spectrum of possible excited states in the produced double hypernuclei the formation of excited states dominates in our model. For different initial target nuclei which absorb the Ξ - , different double hypernuclei nuclei dominate. Thus the ability to assign the various observable γ-transitions in a unique way to a specific double hypernuclei by exploring various light targets as proposed by the PANDA Collaboration seems possible. We also confront our predictions with the correlated pion spectra measured by the E906 Collaboration.

  8. Review of high excitation energy structures in heavy ion collisions: target excitations and three body processes

    International Nuclear Information System (INIS)

    Frascaria, N.

    1987-09-01

    A review of experimental results on high excitation energy structures in heavy ion inelastic scattering is presented. The contribution to the spectra of the pick-up break-up mechanism is discussed in the light of the data obtained with light heavy ion projectiles. Recent results obtained with 40 Ar beams at various energies will show that target excitations contribute strongly to the measured cross section

  9. Mechanism and models for collisional energy transfer in highly excited large polyatomic molecules

    International Nuclear Information System (INIS)

    Gilbert, R. G.

    1995-01-01

    Collisional energy transfer in highly excited molecules (say, 200-500 kJ mol -1 above the zero-point energy of reactant, or of product, for a recombination reaction) is reviewed. An understanding of this energy transfer is important in predicting and interpreting the pressure dependence of gas-phase rate coefficients for unimolecular and recombination reactions. For many years it was thought that this pressure dependence could be calculated from a single energy-transfer quantity, such as the average energy transferred per collision. However, the discovery of 'super collisions' (a small but significant fraction of collisions which transfer abnormally large amounts of energy) means that this simplistic approach needs some revision. The 'ordinary' (non-super) component of the distribution function for collisional energy transfer can be quantified either by empirical models (e.g., an exponential-down functional form) or by models with a physical basis, such as biased random walk (applicable to monatomic or diatomic collision partners) or ergodic (for polyatomic collision partners) treatments. The latter two models enable approximate expressions for the average energy transfer to be estimated from readily available molecular parameters. Rotational energy transfer, important for finding the pressure dependence for recombination reactions, can for these purposes usually be taken as transferring sufficient energy so that the explicit functional form is not required to predict the pressure dependence. The mechanism of 'ordinary' energy transfer seems to be dominated by low-frequency modes of the substrate, whereby there is sufficient time during a vibrational period for significant energy flow between the collision partners. Super collisions may involve sudden energy flow as an outer atom of the substrate is squashed between the substrate and the bath gas, and then is moved away from the interaction by large-amplitude motion such as a ring vibration or a rotation; improved

  10. Excitation and photon decay of giant resonances excited by intermediate energy heavy ions

    International Nuclear Information System (INIS)

    Bertrand, F.E.; Beene, J.R.

    1987-01-01

    Inelastic scattering of medium energy heavy ions provides very large cross sections and peak-to-continuum ratios for excitation of giant resonances. For energies above about 50 MeV/nucleon, giant resonances are excited primarily through Coulomb excitation, which is indifferent to isospin, thus providing a good probe for the study of isovector giant resonances. The extremely large cross sections available from heavy ion excitation permit the study of rare decay modes of the giant resonances. In particular, recent measurements have been made of the photon decay of giant resonances following excitation by 22 and 84 MeV/nucleon 17 O projectiles. The singles results at 84 MeV/nucleon yield peak cross sections for the isoscalar giant quadrupole resonance and the isovector giant dipole resonance of approximately 0.8 and 3 barns/sr, respectively. Data on the ground state decay of the isoscalar giant quadrupole and isovector giant dipole resonances are presented and compared with calculations. Decays to low-lying excited states are also discussed. Preliminary results from an experiment to isolate the 208 Pb isovector quadrupole resonance using its gamma decay are presented. 22 refs., 19 figs., 1 tab

  11. Excited-State Dynamics of Melamine and Its Lysine Derivative Investigated by Femtosecond Transient Absorption Spectroscopy

    Directory of Open Access Journals (Sweden)

    Yuyuan Zhang

    2016-11-01

    Full Text Available Melamine may have been an important prebiotic information carrier, but its excited-state dynamics, which determine its stability under UV radiation, have never been characterized. The ability of melamine to withstand the strong UV radiation present on the surface of the early Earth is likely to have affected its abundance in the primordial soup. Here, we studied the excited-state dynamics of melamine (a proto-nucleobase and its lysine derivative (a proto-nucleoside using the transient absorption technique with a UV pump, and UV and infrared probe pulses. For melamine, the excited-state population decays by internal conversion with a lifetime of 13 ps without coupling significantly to any photochemical channels. The excited-state lifetime of the lysine derivative is slightly longer (18 ps, but the dominant deactivation pathway is otherwise the same as for melamine. In both cases, the vast majority of excited molecules return to the electronic ground state on the aforementioned time scales, but a minor population is trapped in a long-lived triplet state.

  12. International bulletin on atomic and molecular data for fusion. No. 66, August 2007

    International Nuclear Information System (INIS)

    Humbert, D.; Bannister, M.E.; Fuhr, J.; Gilbody, H.B.

    2007-08-01

    Information in this Bulletin is presented in four parts. The Atomic and Molecular Data Information System (AMDIS) of the International Atomic Energy Agency is presented in Part 1. The indexed papers are listed separately for structure and spectra, atomic and molecular collisions, and surface interactions in Part 2. The structure and spectra indexation lines are grouped by process. The first column gives the process, the second one the reactants and then the character of the data contained (Th for theoretical, Ex for experimental, and E/T for both experimental and theoretical). The number in the last column is the reference number in Part 3 of the Bulletin. The atomic and molecular indexation lines are grouped by one collision partner (photon, electron or heavy particle). The first column gives the reactants, the second column gives the process, the third column gives the energy range with the appropriate units, and the last two columns are the same as in the structure and spectra indexation lines. The particle-surface interactions indexation lines are grouped by process. The first column gives the reactants, the second the energy range with the appropriate units, and the last two columns are the same as in the previous cases. Part 3 contains all the bibliographic data for both the indexed and non-indexed references. Those references which are indexed in Part 1 are identified by the repeated indexation lines. The Author Index (Part 4) refers to the bibliographic references contained in Part 3

  13. International bulletin on atomic and molecular data for fusion. No. 68, December 2009

    International Nuclear Information System (INIS)

    Chung, H.K.; Humbert, D.

    2009-12-01

    Information in this Bulletin is presented in four parts. The Atomic and Molecular Data Information System (AMDIS) of the International Atomic Energy Agency is presented in Part 1. The indexed papers are listed separately for structure and spectra, atomic and molecular collisions, and surface interactions in Part 2. The structure and spectra index lines are grouped by process. The first column gives the reactants, the second one the process and then the character of the data contained (Th for theoretical, Ex for experimental, and E/T for both experimental and theoretical). The number in the last column is the reference number in Part 3 of the Bulletin. The atomic and molecular index lines are grouped by one collision partner (photon, electron or heavy particle). The first column gives the reactants, the second column gives the process, the third column gives the energy range with the appropriate units, and the last two columns are the same as in the structure and spectra index lines. The particle-surface interactions index lines are grouped by process. The first column gives the reactants, the second the energy range with the appropriate units, and the last two columns are the same as in the previous cases. Part 3 contains all the bibliographic data for both the indexed and non-indexed references. Those references which are indexed in Part 1 are identified by the repeated index lines. The Author Index (Part 4) refers to the bibliographic references contained in Part 3

  14. International Bulletin on Atomic and Molecular Data for Fusion. No. 67, December 2008

    International Nuclear Information System (INIS)

    Humbert, D.

    2008-12-01

    Information in this Bulletin is presented in four parts. The Atomic and Molecular Data Information System (AMDIS) of the International Atomic Energy Agency is presented in Part 1. The indexed papers are listed separately for structure and spectra, atomic and molecular collisions, and surface interactions in Part 2. The structure and spectra indexation lines are grouped by process. The first column gives the process, the second one the reactants and then the character of the data contained (Th for theoretical, Ex for experimental, and E/T for both experimental and theoretical). The number in the last column is the reference number in Part 3 of the Bulletin. The atomic and molecular indexation lines are grouped by one collision partner (photon, electron or heavy particle). The first column gives the reactants, the second column gives the process, the third column gives the energy range with the appropriate units, and the last two columns are the same as in the structure and spectra indexation lines. The particle-surface interactions indexation lines are grouped by process. The first column gives the reactants, the second the energy range with the appropriate units, and the last two columns are the same as in the previous cases. Part 3 contains all the bibliographic data for both the indexed and non-indexed references. Those references which are indexed in Part 1 are identified by the repeated indexation lines. The Author Index (Part 4) refers to the bibliographic references contained in Part 3.

  15. Isotope separation using vibrationally excited molecules

    International Nuclear Information System (INIS)

    Woodroffe, J.A.; Keck, J.C.

    1977-01-01

    A system for isotope separation or enrichment wherein molecules of a selected isotope type in a flow of molecules of plural isotope types are vibrationally excited and collided with a background gas to provide enhanced diffusivity for the molecules of the selected isotope type permitting their separate collection. The system typically is for the enrichment of uranium using a uranium hexafluoride gas in combination with a noble gas such as argon. The uranium hexafluoride molecules having a specific isotope of uranium are vibrationally excited by laser radiation. The vibrational energy is converted to a translation energy upon collision with a particle of the background gas and the added translation energy enhances the diffusivity of the selected hexafluoride molecules facilitating its condensation on collection surfaces provided for that purpose. This process is periodically interrupted and the cryogenic flow halted to permit evaporation of the collected molecules to provide a distinct, enriched flow

  16. Nuclear Excitations by Antiprotons and Antiprotonic Atoms

    CERN Multimedia

    2002-01-01

    The proposal aims at the investigation of nuclear excitations following the absorption and annihilation of stopped antiprotons in heavier nuclei and at the same time at the study of the properties of antiprotonic atoms. The experimental arrangement will consist of a scintillation counter telescope for the low momentum antiproton beam from LEAR, a beam degrader, a pion multiplicity counter, a monoisotopic target and Ge detectors for radiation and charged particles. The data are stored by an on-line computer.\\\\ \\\\ The Ge detectors register antiprotonic x-rays and nuclear @g-rays which are used to identify the residual nucleus and its excitation and spin state. Coincidences between the two detectors will indicate from which quantum state the antiprotons are absorbed and to which nuclear states the various reactions are leading. The measured pion multiplicity characterizes the annihilation process. Ge&hyphn. and Si-telescopes identify charged particles and determine their energies.\\\\ \\\\ The experiment will gi...

  17. Excitation equilibria in plasmas: a classification

    International Nuclear Information System (INIS)

    Mullen, J.-J.A.M. van der.

    1986-01-01

    In this thesis the author presents a classification of plasmas based on the atomic state distribution function. The study is based on the relation between the distribution function and the underlying processes and starts with the proper understanding of thermodynamic equilibrium (TE). Four types of proper balances are relevant: The 'Maxwell balance' of kinetic energy transfer, the 'Boltzmann balance' of excitation/deexcitation, the 'Saha balance' of ionization/recombination and the 'Planck balance' for interaction of atoms with radiation. Special attention is paid to the distribution function of the ionizing excitation saturation balance. The classification theory of the distribution functions in relation with underlying balances is supported by experimental evidence in an ionizing argon plasma. The AR I system provides a pertinent support of the theory. Experimental facts found in the AR II system can be interpreted in global terms. (Auth.)

  18. Production and de excitation of hot nuclei

    International Nuclear Information System (INIS)

    Auger, F.; Faure, B.; Wirleczki, J.P.; Cunsolo, A.; Foti, A.; Plagnol, E.

    1988-01-01

    We studied Kr induced reactions on C, Al and Ti at 26.4, 34.4 and 45.4 MeV/nucleon. The aims of these experiments were to learn about the influence of the incident energy and asymmetry of the system on the incomplete fusion mechanism, that is on the characteristics (E,l) of the nuclei formed in the reactions and on the competition between massive transfer and preequilibrium emission. We also wanted to study the influence of excitation energy and angular momentum of the nuclei on their deexcitation modes, specially on the competition between light particles (n, p, α) and complex fragments (M>4). Considering the available energies (2.8 < ε < 10.5 MeV/nucleon), the grazing and the total masses (96 ≤ M ≤ 132), nuclei with masses around 100 are likely to be formed with very different excitation energies and angular momenta

  19. Coulomb excitation of {sup 123}Cd

    Energy Technology Data Exchange (ETDEWEB)

    Hartig, Anna-Lena; Kroell, Thorsten; Ilieva, Stoyanka; Boenig, Sabine; Thuerauf, Michael [IKP, TU Darmstadt (Germany); Simpson, Gary; Drouet, Floriane; Ramdhane, Mourad [LPSC, Grenoble (France); Georgiev, Georgi [CSNSM, Orsay (France); Kesteloot, Nele; Wrzosek-Lipska, Kasia [KU, Leuven (Belgium); Jungclaus, Andrea; Illana Sison, Andres [CSIC, Madrid (Spain); Balabanski, Dimiter [INRNE-BAS, Sofia (Bulgaria); Warr, Nigel [Koeln Univ. (Germany). IKP; Voulot, Didier; Wenander, Fredrik; Marsh, Bruce [CERN, Geneva (Switzerland)

    2013-07-01

    On the neutron-rich side of the valley of stability in the vicinity of the double magic nucleus {sup 132}Sn one can find the {sup 123}Cd isotope. Surprisingly the neutron-rich even-A Cd isotopes in this region are showing signs of collectivity beyond that calculated by modern shell-model predictions. In order to gain a deeper insight in this phenomenon we started to extend these studies to odd-A Cd isotopes. As first isotope the exotic nucleus {sup 123}Cd was produced for safe Coulomb excitation by the ISOLDE facility at CERN and post-accelerated by REX-ISOLDE. The γ-decay from excited states was detected with the MINIBALL array. A report on the status of the ongoing analysis is given.

  20. Lifetime measurements of excited Co I levels

    CERN Document Server

    Klotz, W D; Gobel, L H

    1977-01-01

    In the region of 3500 AA the lifetimes of eight excited Cobalt I levels have been measured by means of the zero field level crossing method. The measured lifetimes belong to the odd configurations 3d/sup 7/4s4p and 3d/sup 8/4p and are of the accuracy of about 5%. The hyperfine structure of levels with I not=J has to be taken into account in evaluating lifetimes from level crossing data, because the nuclear spin of the natural isotope /sup 59/Co is I=7/2. Therefore the influence of the line profile of the exciting resonance lines on the lifetimes has been investigated. The results are compared with those of other authors. Furthermore absolute oscillator strengths were calculated with known branching ratios and a new absolute scale has been established. (23 refs).

  1. Statistical density of nuclear excited states

    Directory of Open Access Journals (Sweden)

    V. M. Kolomietz

    2015-10-01

    Full Text Available A semi-classical approximation is applied to the calculations of single-particle and statistical level densities in excited nuclei. Landau's conception of quasi-particles with the nucleon effective mass m* < m is used. The approach provides the correct description of the continuum contribution to the level density for realistic finite-depth potentials. It is shown that the continuum states does not affect significantly the thermodynamic calculations for sufficiently small temperatures T ≤ 1 MeV but reduce strongly the results for the excitation energy at high temperatures. By use of standard Woods - Saxon potential and nucleon effective mass m* = 0.7m the A-dependency of the statistical level density parameter K was evaluated in a good qualitative agreement with experimental data.

  2. Multiflavour excited mesons from the fifth dimension

    Energy Technology Data Exchange (ETDEWEB)

    Paredes, Angel [Centre de Physique Theorique, Ecole Polytechnique, 91128 Palaiseau (France)]. E-mail: angel.paredes@cpht.polytechnique.fr; Talavera, Pere [Departament de Fisica i Enginyeria Nuclear, Universitat Politecnica de Catalunya, Jordi Girona 1-3, E-08034 Barcelona (Spain)]. E-mail: pere.talavera@upc.es

    2005-05-02

    We study the Regge trajectories and the quark-antiquark energy in excited hadrons composed by different dynamical mass constituents via the gauge/string correspondence. First we exemplify the procedure in a supersymmetric system, D3-D7, in the extremal case. Afterwards we discuss the model dual to large-N{sub c} QCD, D4-D6 system. In the latter case we find the field theory expected gross features of vector like theories: the spectrum resembles that of heavy quarkonia and the Chew-Frautschi plot of the singlet and first excited states is in qualitative agreement with those of lattice QCD. We stress the salient points of including different constituents masses.

  3. Multiflavour excited mesons from the fifth dimension

    International Nuclear Information System (INIS)

    Paredes, Angel; Talavera, Pere

    2005-01-01

    We study the Regge trajectories and the quark-antiquark energy in excited hadrons composed by different dynamical mass constituents via the gauge/string correspondence. First we exemplify the procedure in a supersymmetric system, D3-D7, in the extremal case. Afterwards we discuss the model dual to large-N c QCD, D4-D6 system. In the latter case we find the field theory expected gross features of vector like theories: the spectrum resembles that of heavy quarkonia and the Chew-Frautschi plot of the singlet and first excited states is in qualitative agreement with those of lattice QCD. We stress the salient points of including different constituents masses

  4. Excitable particles in an optical torque wrench

    Science.gov (United States)

    Pedaci, Francesco; Huang, Zhuangxiong; van Oene, Maarten; Barland, Stephane; Dekker, Nynke H.

    2011-03-01

    The optical torque wrench is a laser trapping technique capable of applying and directly measuring torque on microscopic birefringent particles using spin momentum transfer, and has found application in the measurement of static torsional properties of biological molecules such as single DNAs. Motivated by the potential of the optical torque wrench to access the fast rotational dynamics of biological systems, a result of its all-optical manipulation and detection, we focus on the angular dynamics of the trapped birefringent particle, demonstrating its excitability in the vicinity of a critical point. This links the optical torque wrench to nonlinear dynamical systems such as neuronal and cardiovascular tissues, nonlinear optics and chemical reactions, all of which display an excitable binary (`all-or-none') response to input perturbations. On the basis of this dynamical feature, we devise and implement a conceptually new sensing technique capable of detecting single perturbation events with high signal-to-noise ratio and continuously adjustable sensitivity.

  5. Antiferromagnetic resonance excited by oscillating electric currents

    Science.gov (United States)

    Sluka, Volker

    2017-12-01

    In antiferromagnetic materials the order parameter exhibits resonant modes at frequencies that can be in the terahertz range, making them interesting components for spintronic devices. Here, it is shown that antiferromagnetic resonance can be excited using the inverse spin-Hall effect in a system consisting of an antiferromagnetic insulator coupled to a normal-metal waveguide. The time-dependent interplay between spin torque, ac spin accumulation, and magnetic degrees of freedom is studied. It is found that the dynamics of the antiferromagnet affects the frequency-dependent conductivity of the normal metal. Further, a comparison is made between spin-current-induced and Oersted-field-induced excitation under the condition of constant power injection.

  6. The triplet excited state of bilirubin

    International Nuclear Information System (INIS)

    Land, E.J.

    1976-01-01

    Pulse radiolysis of benzene solutions of 40 μM bilirubin alone or with 0.1 M biphenyl has yielded evidence for the formation of the triplet excited state of bilirubin. Measurements were made of a number of properties, including the absorption spectrum (lambdasub(max)500nm), lifetime 9μs), extinction coefficient (8800 M -1 cm -1 ), energy level (approximately 150 kJ mol -1 ) and the rate of quenching by oxygen (rate constant, 8.2 x 10 8 M -1 s -1 ). An upper limit of 0.1 has also been obtained for the singlet to triplet crossover efficiency of bilirubin following excitation by 353 nm radiation. Consideration is given to the relevance of these data to the mechanism of bilirubin photo-destruction, both in vivo and in vitro. (U.K.)

  7. Calculations of coincident ionization plus excitation

    International Nuclear Information System (INIS)

    Becker, R.L.

    1986-01-01

    For Li- and Be-like ions, K x-ray yields, together with detection that the ionic charge has increased, give the cross section for ionization plus excitation (IE), a process which can exhibit electron-electron correlations. Measurements of IE for 14 Si 11+ + He stimulated our coupled-channels calculations in the independent-Fermi-particle model (IFPM), which includes Pauli correlations. We discuss how the IFPM expressions, generalized here to include an open shell, differ from those for distinguishable electrons. The sensitivity of σ/sub IE/ to correlations is shown. Recent additional measurements and future ones giving excitation functions for resolved configurations and complementary Auger data will provide even more sensitive tests of collisional correlation theory. 15 refs., 3 figs., 1 tab

  8. Quadrupole collective excitations in rapidly rotating nuclej

    International Nuclear Information System (INIS)

    Mikhajlov, I.N.

    1983-01-01

    The spectrum of collective quadrupole excitations in nuclei is investigated. The average nucleus field has the axial symmetry and rotation occurs relatively to this axis. Dependences of the spectrum of quadrupole oscillations on rotation rate for classic liquid drop (CLD) and for a drop of fermi-liquid (DFL) with fissionability parameter X=0.62 ( 154 Er) are presented. The dependence of probabilities of E2-transitions between single-phonon and phonon-free states on rotation rate for CLD and DFL with fussionability parameter X=0.62 ( 154 Er) is also presented. It is shown that for CLD collective E2-transition of states of yrast-consequence is absolutely forbidden. For DFL transitions are possible that lead to decay of phonon-free state with the excitation of phonons of γ-modes and decrease of angular momentum

  9. Excitations of single-beauty hadrons

    Science.gov (United States)

    Burch, Tommy; Hagen, Christian; Lang, Christian B.; Limmer, Markus; Schäfer, Andreas

    2009-01-01

    In this work we study the predominantly orbital and radial excitations of hadrons containing a single heavy quark. We present meson and baryon mass splittings and ratios of meson decay constants (e.g., fBs/fB and fBs'/fBs) resulting from quenched and dynamical two-flavor configurations. Light quarks are simulated using the chirally improved lattice Dirac operator at valence masses as light as Mπ≈350MeV. The heavy quark is approximated by a static propagator, appropriate for the b quark on our lattices (1/ã1-2GeV). We also include some preliminary calculations of the O(1/mQ) kinetic corrections to the states, showing, in the process, a viable way of applying the variational method to three-point functions involving excited states. We compare our results with recent experimental findings.

  10. Excitations of single-beauty hadrons

    International Nuclear Information System (INIS)

    Burch, Tommy; Hagen, Christian; Lang, Christian B.; Limmer, Markus; Schaefer, Andreas

    2009-01-01

    In this work we study the predominantly orbital and radial excitations of hadrons containing a single heavy quark. We present meson and baryon mass splittings and ratios of meson decay constants (e.g., f B s /f B and f B s ' /f B s ) resulting from quenched and dynamical two-flavor configurations. Light quarks are simulated using the chirally improved lattice Dirac operator at valence masses as light as M π ≅350 MeV. The heavy quark is approximated by a static propagator, appropriate for the b quark on our lattices (1/a∼1-2 GeV). We also include some preliminary calculations of the O(1/m Q ) kinetic corrections to the states, showing, in the process, a viable way of applying the variational method to three-point functions involving excited states. We compare our results with recent experimental findings.

  11. Isovector excitations in charge independent systems

    International Nuclear Information System (INIS)

    Menezes, D.P.

    1986-01-01

    A method for building states with good isospin, from states given by the action of an isovector excitation operator on states of the parent multiplet is developed. This new method is a generalization of Toki's method and is applicable to cases involving any isovector excitation operator and a parent state, which is not a double magic nucleus. Once obtained these states with well defined isospin, it is shown how to do a Tamm-Dancoff calculation for determining the energy levels. The transition matrix elements of an isotensor operator are also calculated. An application of this formalism to the Gamow-Teller transition strength in 90 Zr is studied. In this case, besides the double magic configuration, the 2 particles - 2 holes (Π1g 9/2 ) 2 (υ 2p 1/2 -1 ) 2 configuration is also considered. (author) [pt

  12. Search for Excited Electrons at HERA

    CERN Document Server

    Adloff, C.; Andrieu, B.; Anthonis, T.; Astvatsatourov, A.; Babaev, A.; Bahr, J.; Baranov, P.; Barrelet, E.; Bartel, W.; Baumgartner, S.; Becker, J.; Beckingham, M.; Beglarian, A.; Behnke, O.; Belousov, A.; Berger, C.; Berndt, T.; Bizot, J.C.; Bohme, J.; Boudry, V.; Braunschweig, W.; Brisson, V.; Broker, H.B.; Brown, D.P.; Bruncko, D.; Busser, F.W.; Bunyatyan, A.; Burrage, A.; Buschhorn, G.; Bystritskaya, L.; Campbell, A.J.; Caron, S.; Cassol-Brunner, F.; Clarke, D.; Collard, C.; Contreras, J.G.; Coppens, Y.R.; Coughlan, J.A.; Cousinou, M.C.; Cox, B.E.; Cozzika, G.; Cvach, J.; Dainton, J.B.; Dau, W.D.; Daum, K.; Davidsson, M.; Delcourt, B.; Delerue, N.; Demirchyan, R.; De Roeck, A.; De Wolf, E.A.; Diaconu, C.; Dingfelder, J.; Dixon, P.; Dodonov, V.; Dowell, J.D.; Droutskoi, A.; Dubak, A.; Duprel, C.; Eckerlin, Guenter; Eckstein, D.; Efremenko, V.; Egli, S.; Eichler, R.; Eisele, F.; Eisenhandler, E.; Ellerbrock, M.; Elsen, E.; Erdmann, M.; Erdmann, W.; Faulkner, P.J.W.; Favart, L.; Fedotov, A.; Felst, R.; Ferencei, J.; Ferron, S.; Fleischer, M.; Fleischmann, P.; Fleming, Y.H.; Flugge, G.; Fomenko, A.; Foresti, I.; Formanek, J.; Franke, G.; Frising, G.; Gabathuler, E.; Gabathuler, K.; Garvey, J.; Gassner, J.; Gayler, Joerg; Gerhards, R.; Gerlich, C.; Ghazaryan, Samvel; Goerlich, L.; Gogitidze, N.; Grab, C.; Grabski, V.; Grassler, H.; Greenshaw, T.; Grindhammer, Guenter; Hadig, T.; Haidt, D.; Hajduk, L.; Haller, J.; Heinemann, B.; Heinzelmann, G.; Henderson, R.C.W.; Hengstmann, S.; Henschel, H.; Heremans, R.; Herrera, G.; Herynek, I.; Hildebrandt, M.; Hilgers, M.; Hiller, K.H.; Hladky, J.; Hoting, P.; Hoffmann, D.; Horisberger, R.; Hovhannisyan, A.; Hurling, S.; Ibbotson, M.; Issever, C.; Jacquet, M.; Jaffre, M.; Janauschek, L.; Janssen, X.; Jemanov, V.; Jonsson, L.; Johnson, C.; Johnson, D.P.; Jones, M.A.S.; Jung, H.; Kant, D.; Kapichine, M.; Karlsson, M.; Karschnick, O.; Katzy, J.; Keil, F.; Keller, N.; Kennedy, J.; Kenyon, I.R.; Kiesling, Christian M.; Kjellberg, P.; Klein, M.; Kleinwort, C.; Kluge, T.; Knies, G.; Koblitz, B.; Kolya, S.D.; Korbel, V.; Kostka, P.; Kotelnikov, S.K.; Koutouev, R.; Koutov, A.; Kroseberg, J.; Kruger, K.; Kuhr, T.; Lamb, D.; Landon, M.P.J.; Lange, W.; Lastovicka, T.; Laycock, P.; Lebailly, E.; Lebedev, A.; Leissner, B.; Lemrani, R.; Lendermann, V.; Levonian, S.; List, B.; Lobodzinska, E.; Lobodzinski, B.; Loginov, A.; Loktionova, N.; Lubimov, V.; Luders, S.; Luke, D.; Lytkin, L.; Malden, N.; Malinovski, E.; Mangano, S.; Maracek, R.; Marage, P.; Marks, J.; Marshall, R.; Martyn, H.U.; Martyniak, J.; Maxfield, S.J.; Meer, D.; Mehta, A.; Meier, K.; Meyer, A.B.; Meyer, H.; Meyer, J.; Michine, S.; Mikocki, S.; Milstead, D.; Mohrdieck, S.; Mondragon, M.N.; Moreau, F.; Morozov, A.; Morris, J.V.; Muller, K.; Murin, P.; Nagovizin, V.; Naroska, B.; Naumann, J.; Naumann, T.; Newman, Paul R.; Niebergall, F.; Niebuhr, C.; Nix, O.; Nowak, G.; Nozicka, M.; Olivier, B.; Olsson, J.E.; Ozerov, D.; Panassik, V.; Pascaud, C.; Patel, G.D.; Peez, M.; Perez, E.; Petrukhin, A.; Phillips, J.P.; Pitzl, D.; Poschl, R.; Potachnikova, I.; Povh, B.; Rauschenberger, J.; Reimer, P.; Reisert, B.; Risler, C.; Rizvi, E.; Robmann, P.; Roosen, R.; Rostovtsev, A.; Rusakov, S.; Rybicki, K.; Sankey, D.P.C.; Schatzel, S.; Scheins, J.; Schilling, F.P.; Schleper, P.; Schmidt, D.; Schmidt, S.; Schmitt, S.; Schneider, M.; Schoeffel, L.; Schoning, A.; Schorner, T.; Schroder, V.; Schultz-Coulon, H.C.; Schwanenberger, C.; Sedlak, K.; Sefkow, F.; Chekelian, V.; Sheviakov, I.; Shtarkov, L.N.; Sirois, Y.; Sloan, T.; Smirnov, P.; Soloviev, Y.; South, D.; Spaskov, V.; Specka, Arnd E.; Spitzer, H.; Stamen, R.; Stella, B.; Stiewe, J.; Strauch, I.; Straumann, U.; Tchetchelnitski, S.; Thompson, Graham; Thompson, P.D.; Tomasz, F.; Traynor, D.; Truoel, Peter; Tsipolitis, G.; Tsurin, I.; Turnau, J.; Turney, J.E.; Tzamariudaki, E.; Uraev, A.; Urban, Marcel; Usik, A.; Valkar, S.; Valkarova, A.; Vallee, C.; Van Mechelen, P.; Vargas Trevino, A.; Vassiliev, S.; Vazdik, Y.; Veelken, C.; Vest, A.; Vichnevski, A.; Wacker, K.; Wagner, J.; Wallny, R.; Waugh, B.; Weber, G.; Wegener, D.; Werner, C.; Werner, N.; Wessels, M.; White, G.; Wiesand, S.; Wilksen, T.; Winde, M.; Winter, G.G.; Wissing, C.; Wobisch, M.; Woehrling, E.E.; Wunsch, E.; Wyatt, A.C.; Zacek, J.; Zalesak, J.; Zhang, Z.; Zhokin, A.; Zomer, F.; zur Nedden, M.

    2002-01-01

    A search for excited electron e* production is described in which the electroweak decays e*->e gamma, e*->e Z and e*->nu W are considered. The data used correspond to an integrated luminosity of 120 pb^(-1) taken in e^(+-)p collisions from 1994 to 2000 with the H1 detector at HERA at centre-of-mass energies of 300 and 318 GeV. No evidence for a signal is found. Mass dependent exclusion limits are derived for the ratio of the couplings to the compositeness scale, f/Lambda. These limits extend the excluded region to higher masses than has been possible in previous direct searches for excited electrons.

  13. Charge exchange with ion excitation: asymptotic theory

    International Nuclear Information System (INIS)

    Ivakin, I.A.; Karbovanets, M.I.; Ostrovskii, V.N.

    1987-01-01

    There is developed an asymptotic (with respect to the large internuclear separation R) theory for computing the matrix element of the exchange interaction between states of quasimolecules, which is responsible for charge transfer with ion excitation: B + +A→B+A + *. A semiclassical approximation is used, which enables one to apply the theory to processes with the participation of multiply charged ions. The case of s--s transitions for excitation of the ion A + →A + *, where it is appropriate to take into account the distortion of the wave functions of the ion A + by the particle B, is treated separately. Calculations of cross sections and comparison with the results of experiments for He + --Cd and Ne + --Mg collisions at thermal energies are given. It is shown that it is impossible to explain the experimental data by the interaction of terms of the quasimolecules at large R only, and a possible mechanism for populating at small R is proposed

  14. Numerical simulations of convectively excited gravity waves

    International Nuclear Information System (INIS)

    Glatzmaier, G.A.

    1983-01-01

    Magneto-convection and gravity waves are numerically simulated with a nonlinear, three-dimensional, time-dependent model of a stratified, rotating, spherical fluid shell heated from below. A Solar-like reference state is specified while global velocity, magnetic field, and thermodynamic perturbations are computed from the anelastic magnetohydrodynamic equations. Convective overshooting from the upper (superadiabatic) part of the shell excites gravity waves in the lower (subadiabatic) part. Due to differential rotation and Coriolis forces, convective cell patterns propagate eastward with a latitudinally dependent phase velocity. The structure of the excited wave motions in the stable region is more time-dependent than that of the convective motions above. The magnetic field tends to be concentrated over giant-cell downdrafts in the convective zone but is affected very little by the wave motion in the stable region

  15. Multi-quasiparticle excitations in 145Tb

    International Nuclear Information System (INIS)

    Zheng Yong; Zhou Xiaohong; Zhang Yuhu; Liu Minliang; Guo Yingxiang; Lei Xiangguo; Kusakari, H.; Sugawara, M.

    2004-01-01

    High-spin states in 145 Tb have been populated using the 118 Sn( 32 S, 1p4n) reaction at a beam energy of 165 MeV. The level scheme of 145 Tb has been established for the first time. The level scheme shows characteristics of spherical or slightly oblate nucleus. Based on the systematic trends of the level structure in the neighboring N=80 isotones, the level structure in 145 Tb below 2 MeV excitation is well explained by coupling an h 11/2 valence proton to the even-even 144 Gd core. Above 2 MeV excitation, most of the yrast levels are interpreted with multi-quasiparticle shell-model configurations. (authors)

  16. Alfven wave excitation in a cavity with a transverse magnetic field

    International Nuclear Information System (INIS)

    Bures, M.

    1982-12-01

    A transversely magnetized cylindrical plasma model with an internal rod conductor is used to approximate the FIVA internal ring device of Spherator type with a purely poloidal magnetic field. It is shown that an excitation asymmetry along the plasma column, i.e. with a wave number k sub (z) does not equal 0, introduces a coupling between the magnetoacoustic and shear Alfven waves in the frequency range #betta#<<#betta# sub (ci). The introduction of an equilibrium mass motion along the plasma cylinder introduces a flow continuum. Simultaneously the Alfven resonance frequency becomes Doppler shifted. The experimental observations indicate that cavity modes do not build up in the FIVA device in the case of nonsymmetric excitation. If on the other hand the exciting structure becomes symmetric, i.e. with k sub (z) equals 0, the magnetoacoustic resonance become excited. The resulting Q values are rather low which indicates that the coupling to the shear wave through the Hall electric field cannot be neglected. (Author)

  17. Magnetic Excitations and Magnetic Ordering in Praseodymium

    DEFF Research Database (Denmark)

    Houmann, Jens Christian Gylden; Chapellier, M.; Mackintosh, A. R.

    1975-01-01

    The dispersion relations for magnetic excitons propagating on the hexagonal sites of double-hcp Pr provide clear evidence for a pronounced anisotropy in the exchange. The energy of the excitations decreases rapidly as the temperature is lowered, but becomes almost constant below about 7 K......, in agreement with a random-phase-approximation calculation. No evidence of magnetic ordering has been observed above 0.4 K, although the exchange is close to the critical value necessary for an antiferromagnetic state....

  18. Electroluminescence from graphene excited by electron tunneling

    International Nuclear Information System (INIS)

    Beams, Ryan; Bharadwaj, Palash; Novotny, Lukas

    2014-01-01

    We use low-energy electron tunneling to excite electroluminescence in single layer graphene. Electrons are injected locally using a scanning tunneling microscope and the luminescence is analyzed using a wide-angle optical imaging system. The luminescence can be switched on and off by inverting the tip–sample bias voltage. The observed luminescence is explained in terms of a hot luminescence mechanism. (paper)

  19. Charges and Electromagnetic Radiation as Topological Excitations

    Directory of Open Access Journals (Sweden)

    Manfried Faber

    2017-01-01

    Full Text Available We discuss a model with stable topological solitons in Minkowski space with only three degrees of freedom, the rotational angles of a spatial Dreibein. This model has four types of solitons differing in two topological quantum numbers which we identify with electric charge and spin. The vacuum has a two-dimensional degeneracy leading to two types of massless excitations, characterised by a topological quantum number which could have a physical equivalent in the photon number.

  20. Controlling nonlinear waves in excitable media

    International Nuclear Information System (INIS)

    Puebla, Hector; Martin, Roland; Alvarez-Ramirez, Jose; Aguilar-Lopez, Ricardo

    2009-01-01

    A new feedback control method is proposed to control the spatio-temporal dynamics in excitable media. Applying suitable external forcing to the system's slow variable, successful suppression and control of propagating pulses as well as spiral waves can be obtained. The proposed controller is composed by an observer to infer uncertain terms such as diffusive transport and kinetic rates, and an inverse-dynamics feedback function. Numerical simulations shown the effectiveness of the proposed feedback control approach.

  1. Controlling nonlinear waves in excitable media

    Energy Technology Data Exchange (ETDEWEB)

    Puebla, Hector [Departamento de Energia, Universidad Autonoma Metropolitana, Av. San Pablo No. 180, Reynosa-Tamaulipas, Azcapotzalco 02200, DF, Mexico (Mexico)], E-mail: hpuebla@correo.azc.uam.mx; Martin, Roland [Laboratoire de Modelisation et d' Imagerie en Geosciences, CNRS UMR and INRIA Futurs Magique-3D, Universite de Pau (France); Alvarez-Ramirez, Jose [Division de Ciencias Basicas e Ingenieria, Universidad Autonoma Metropolitana-Iztapalapa (Mexico); Aguilar-Lopez, Ricardo [Departamento de Biotecnologia y Bioingenieria, CINVESTAV-IPN (Mexico)

    2009-01-30

    A new feedback control method is proposed to control the spatio-temporal dynamics in excitable media. Applying suitable external forcing to the system's slow variable, successful suppression and control of propagating pulses as well as spiral waves can be obtained. The proposed controller is composed by an observer to infer uncertain terms such as diffusive transport and kinetic rates, and an inverse-dynamics feedback function. Numerical simulations shown the effectiveness of the proposed feedback control approach.

  2. Self-excitation of space charge waves

    DEFF Research Database (Denmark)

    Lyuksyutov, Sergei; Buchhave, Preben; Vasnetsov, Mikhail

    1997-01-01

    We report a direct observation of space charge waves in photorefractive crystals with point group 23 (sillenites) based on their penetration into an area with uniform light illumination. It is shown experimentally that the quality factor of the waves increases substantially with respect to what c...... current theory predicts [B. Sturman el al., Appl. Phys. A 55, 235 (1992)]. This results in the appearance of strong spontaneous beams caused by space charge wave self-excitation....

  3. Particle decay of (12)Be excited states

    NARCIS (Netherlands)

    Charity, R. J.; Komarov, S. A.; Sobotka, L. G.; Clifford, J.; Bazin, D.; Gade, A.; Lee, Jenny; Lukyanov, S. M.; Lynch, W. G.; Mocko, M.; Lobastov, S. P.; Rogers, A. M.; Sanetullaev, A.; Tsang, M. B.; Wallace, M. S.; Hudan, S.; Metelko, C.; Famiano, M. A.; Wuosmaa, A. H.; van Goethem, M. J.

    2007-01-01

    The breakup of E/A=50 MeV (12)Be fragments following inelastic scattering off of hydrogen and carbon target nuclei has been studied. The breakup channels alpha+(8)He, (6)He+(6)He, t+(9)Li, and p+(11)Li were observed. Two doublets at excitation energies of 12.8 and 15.5 MeV were found for the

  4. Neutron excitation function guide for reactor dosimetry

    International Nuclear Information System (INIS)

    Gritzay, O.; Vlasov, M.; Chervonna, L.; Klimova, N.; Kolota, G.; Zerkin, V.

    2002-01-01

    Neutron Excitation Function Guide for Reactor Dosimetry (NEFGRD) has been prepared in the Ukrainian Nuclear Data Center (UKRNDC) using ZVV 9.2 code for graphical data presentation. The data can be retrieved through Web or obtained on CD-ROM or as hard copy report. NEFGRD contains graphical and text information for 56 nuclides (81 dosimetry reactions). Each reaction is provided by the information part and several graphical function blocks (from one to nine). (author)

  5. Fractal effects on excitations in diluted ferromagnets

    International Nuclear Information System (INIS)

    Kumar, D.

    1981-08-01

    The low energy spin-wave like excitations in diluted ferromagnets near percolation threshold are studied. For this purpose an explicit use of the fractal model for the backbone of the infinite percolating cluster due to Kirkpatrick is made. Three physical effects are identified, which cause the softening of spin-waves as the percolation point is approached. The importance of fractal effects in the calculation of density of states and the low temperature thermodynamics is pointed out. (author)

  6. Electronic excitation and Auger spectroscopy of hexamethyldissilane

    International Nuclear Information System (INIS)

    Souza, G.G.B. de; Azevedo e Souza, A.C. de; Martins, R.J.; Lucas, C.A.

    1988-01-01

    In this work, it is presented an spectroscopic study of Si 2 (CH 3 ) 6 which presents interesting characteristics in the Si - Si bond. Electron energy loss technique was used in the energy range of 500 - 200 eV for the electron beam. Electronic excitation spectra were obtained for the energy loss range from 5 to 30 eV, and also Auger spectra. (A.C.A.S.) [pt

  7. Radial excitations in nucleon-nucleon scattering

    International Nuclear Information System (INIS)

    Silvestre-Brac, B.; Carbonell, J.; Gignoux, C.

    1986-01-01

    In the non-relativistic constituent quark model, the role of the radial excitations of the nucleon is studied within a resonating group approach of the nucleon-nucleon scattering. It is shown that, rather than the inclusion of new channels, it is important to include mixed-symmetry spin-isospin components in the nucleon wave function. It is also found that during the collision there is no significant deformation of the nucleon. (orig.)

  8. Hot nuclei, limiting temperatures and excitation energies

    International Nuclear Information System (INIS)

    Peter, J.

    1986-09-01

    Hot fusion nuclei are produced in heavy ion collisions at intermediate energies (20-100 MeV/U). Information on the maximum excitation energy per nucleon -and temperatures- indicated by the experimental data is compared to the predictions of static and dynamical calculations. Temperatures around 5-6 MeV are reached and seem to be the limit of formation of thermally equilibrated fusion nuclei

  9. Axonal excitability properties in amyotrophic lateral sclerosis.

    Science.gov (United States)

    Vucic, Steve; Kiernan, Matthew C

    2006-07-01

    To investigate axolemmal ion channel function in patients diagnosed with sporadic amyotrophic lateral sclerosis (ALS). A recently described threshold tracking protocol was implemented to measure multiple indices of axonal excitability in 26 ALS patients by stimulating the median motor nerve at the wrist. The excitability indices studied included: stimulus-response curve (SR); strength-duration time constant (tauSD); current/threshold relationship; threshold electrotonus to a 100 ms polarizing current; and recovery curves to a supramaximal stimulus. Compound muscle action potential (CMAP) amplitudes were significantly reduced in ALS patients (ALS, 2.84+/-1.17 mV; controls, 8.27+/-1.09 mV, P<0.0005) and the SR curves for both 0.2 and 1 ms pulse widths were shifted in a hyperpolarized direction. Threshold electrotonus revealed a greater threshold change to both depolarizing and hyperpolarizing conditioning stimuli, similar to the 'fanned out' appearance that occurs with membrane hyperpolarization. The tauSD was significantly increased in ALS patients (ALS, 0.50+/-0.03 ms; controls, 0.42+/-0.02 ms, P<0.05). The recovery cycle of excitability following a conditioning supramaximal stimulus revealed increased superexcitability in ALS patients (ALS, 29.63+/-1.25%; controls, 25.11+/-1.01%, P<0.01). Threshold tracking studies revealed changes indicative of widespread dysfunction in axonal ion channel conduction, including increased persistent Na+ channel conduction, and abnormalities of fast paranodal K+ and internodal slow K+ channel function, in ALS patients. An increase in persistent Na+ conductances coupled with reduction in K+ currents would predispose axons of ALS patients to generation of fasciculations and cramps. Axonal excitability studies may provide insight into mechanisms responsible for motor neuron loss in ALS.

  10. Electron spectroscopy of collisional excited atoms

    International Nuclear Information System (INIS)

    Straten, P. van der.

    1987-01-01

    In this thesis measurements are described in which coincidences are detected between scattered projectiles and emitted electrons. This yields information on two-electron excitation processes. In order to show what can be learnt from coincidence experiments a detailed theoretical analysis is given. The transition amplitudes, which contain all the information, are introduced (ch.2). In ch.3 the experimental set-up is shown. The results for the Li + -He system are shown in ch. 7 and are compared with predictions based on the Molecular-Orbitalmodel which however does not account for two-excitation mechanisms. With the transition amplitudes also the wave function of the excited atom has been completely determined. In ch.8 the shape of the electron cloud, induced by the collision, is derived from the amplitudes. The relation between the oscillatory motion of this cloud after the collision and the correlation between the two electrons of the excited atom is discussed. In ch. 6 it is shown that the broad structures in the non-coincident energy spectra of the Li + -He system are erroneously interpretated as a result of electron emission from the (Li-He) + -quasimolecule. A model is presented which explains, based on the results obtained from the coincidence measurements, these broad structures. In ch. 4 the Post-Collision Interaction process is treated. It is shown that for high-energy collisions, in contrast with general assumptions, PCI is important. In ch. 5 the importance of PCI-processes in photoionization of atoms, followed by Auger decay, are studied. From the formulas derived in ch. 4 simple analytical results are obtained. These are applied to recent experiments and good agreement is achieved. 140 refs.; 55 figs.; 9 tabs

  11. Dynamical analysis of highly excited molecular spectra

    Energy Technology Data Exchange (ETDEWEB)

    Kellman, M.E. [Univ. of Oregon, Eugene (United States)

    1993-12-01

    The goal of this program is new methods for analysis of spectra and dynamics of highly excited vibrational states of molecules. In these systems, strong mode coupling and anharmonicity give rise to complicated classical dynamics, and make the simple normal modes analysis unsatisfactory. New methods of spectral analysis, pattern recognition, and assignment are sought using techniques of nonlinear dynamics including bifurcation theory, phase space classification, and quantization of phase space structures. The emphasis is chaotic systems and systems with many degrees of freedom.

  12. Rearrangements in ground and excited states

    CERN Document Server

    de Mayo, Paul

    1980-01-01

    Rearrangements in Ground and Excited States, Volume 2 covers essays on the theoretical approach of rearrangements; the rearrangements involving boron; and the molecular rearrangements of organosilicon compounds. The book also includes essays on the polytopal rearrangement at phosphorus; the rearrangement in coordination complexes; and the reversible thermal intramolecular rearrangements of metal carbonyls. Chemists and people involved in the study of rearrangements will find the book invaluable.

  13. Nonlinear stability of spin-flip excitations

    International Nuclear Information System (INIS)

    Arunasalam, V.

    1975-01-01

    A rather complete discussion of the nonlinear electrodynamic behavior of a negative-temperature spin system is presented. The method presented here is based on a coupled set of master equations, one describing the time evolution of the photon (i.e., the spin-flip excitation) distribution function and the other describing the time evolution of the particle distribution function. It is found that the initially unstable (i.e., growing) spin-flip excitations grow to such a large amplitude that their nonlinear reaction on the particle distribution function becomes important. It is then shown that the initially totally inverted two-level spin system evolves rapidly (through this nonlinear photon-particle coupling) towards a quasilinear steady state where the populations of the spin-up and the spin-down states are equal to each other. Explicit expressions for the time taken to reach this quasilinear steady state and the energy in the spin-flip excitations at this state are also presented

  14. Demystifying autofluorescence with excitation scanning hyperspectral imaging

    Science.gov (United States)

    Deal, Joshua; Harris, Bradley; Martin, Will; Lall, Malvika; Lopez, Carmen; Rider, Paul; Boudreaux, Carole; Rich, Thomas; Leavesley, Silas J.

    2018-02-01

    Autofluorescence has historically been considered a nuisance in medical imaging. Many endogenous fluorophores, specifically, collagen, elastin, NADH, and FAD, are found throughout the human body. Diagnostically, these signals can be prohibitive since they can outcompete signals introduced for diagnostic purposes. Recent advances in hyperspectral imaging have allowed the acquisition of significantly more data in a shorter time period by scanning the excitation spectra of fluorophores. The reduced acquisition time and increased signal-to-noise ratio allow for separation of significantly more fluorophores than previously possible. Here, we propose to utilize excitation-scanning of autofluorescence to examine tissues and diagnose pathologies. Spectra of autofluorescent molecules were obtained using a custom inverted microscope (TE-2000, Nikon Instruments) with a Xe arc lamp and thin film tunable filter array (VersaChrome, Semrock, Inc.) Scans utilized excitation wavelengths from 360 nm to 550 nm in 5 nm increments. The resultant spectra were used to examine hyperspectral image stacks from various collaborative studies, including an atherosclerotic rat model and a colon cancer study. Hyperspectral images were analyzed with ENVI and custom Matlab scripts including linear spectral unmixing (LSU) and principal component analysis (PCA). Initial results suggest the ability to separate the signals of endogenous fluorophores and measure the relative concentrations of fluorophores among healthy and diseased states of similar tissues. These results suggest pathology-specific changes to endogenous fluorophores can be detected using excitationscanning hyperspectral imaging. Future work will expand the library of pure molecules and will examine more defined disease states.

  15. Field theories with multiple fermionic excitations

    International Nuclear Information System (INIS)

    Crawford, J.P.

    1978-01-01

    The reason for the existence of the muon has been an enigma since its discovery. Since that time there has been a continuing proliferation of elementary particles. It is proposed that this proliferation of leptons and quarks is comprehensible if there are only four fundamental particles, the leptons ν/sub e/ and e - , and the quarks u and d. All other leptons and quarks are imagined to be excited states of these four fundamental entities. Attention is restricted to the charged leptons and the electromagnetic interactions only. A detailed study of a field theory in which there is only one fundamental charged fermionic field having two (or more) excitations is made. When the electromagnetic interactions are introduced and the theory is second quantized, under certain conditions this theory reproduces the S matrix obtained from usual OED. In this case no electromagnetic transitions are allowed. A leptonic charge operator is defined and a superselection rule for this leptonic charge is found. Unfortunately, the mass spectrum cannot be obtained. This theory has many renormalizable generalizations including non-abelian gauge theories, Yukawa-type theories, and Fermi-type theories. Under certain circumstances the Yukawa- and Fermi-type theories are finite in perturbation theory. It is concluded that there are no fundamental objections to having fermionic fields with more than one excitation

  16. Seismic Excitation of the Polar Motion

    Science.gov (United States)

    Chao, Benjamin Fong; Gross, Richard S.; Han, Yan-Ben

    1996-01-01

    The mass redistribution in the earth as a result of an earthquake faulting changes the earth's inertia tensor, and hence its rotation. Using the complete formulae developed by Chao and Gross (1987) based on the normal mode theory, we calculated the earthquake-induced polar motion excitation for the largest 11,015 earthquakes that occurred during 1977.0-1993.6. The seismic excitations in this period are found to be two orders of magnitude below the detection threshold even with today's high precision earth rotation measurements. However, it was calculated that an earthquake of only one tenth the size of the great 1960 Chile event, if happened today, could be comfortably detected in polar motion observations. Furthermore, collectively these seismic excitations have a strong statistical tendency to nudge the pole towards approx. 140 deg E, away from the actually observed polar drift direction. This non-random behavior, similarly found in other earthquake-induced changes in earth rotation and low-degree gravitational field by Chao and Gross (1987), manifests some geodynamic behavior yet to be explored.

  17. Analytical study of doubly excited ridge states

    International Nuclear Information System (INIS)

    Wong, H.Y.

    1988-01-01

    Two different non-separable problems are explored and analyzed. Non-perturbative methods need to be used to handle them, as the competing forces involved in these problems are equally strong and do not yield to a perturbative analysis. The first one is the study of doubly excited ridge states of atoms, in which two electrons are comparably excited. An analytical wavefunction for such states is introduced and is used to solve the two-electron Hamiltonian in the pair coordinates called hyperspherical coordinates variationally. The correlation between the electrons is built in analytically into the structure of the wavefunction. Sequences of ridge states out to very high excitation are computed and are organized as Rydberg series converging to the double ionization limit. Numerical results of such states in He and H - are compared with other theoretical calculations where available. The second problem is the analysis of the photodetachment of negative ions in an electric field via the frame transformation theory. The presence of the electron field requires a transformation from spherical to cylindrical symmetry for the outgoing photoelectron. This gives an oscillatory modulating factor as the effect of the electric field on cross-sections. All of this work is derived analytically in a general form applicable to the photodetachment of any negative ion. The expressions are applied to H - and S - for illustration

  18. Excitation mechanisms for Jovian seismic modes

    Science.gov (United States)

    Markham, Steve; Stevenson, Dave

    2018-05-01

    Recent (2011) results from the Nice Observatory indicate the existence of global seismic modes on Jupiter in the frequency range between 0.7 and 1.5 mHz with amplitudes of tens of cm/s. Currently, the driving force behind these modes is a mystery; the measured amplitudes are many orders of magnitude larger than anticipated based on theory analogous to helioseismology (that is, turbulent convection as a source of stochastic excitation). One of the most promising hypotheses is that these modes are driven by Jovian storms. This work constructs a framework to analytically model the expected equilibrium normal mode amplitudes arising from convective columns in storms. We also place rough constraints on Jupiter's seismic modal quality factor. Using this model, neither meteor strikes, turbulent convection, nor water storms can feasibly excite the order of magnitude of observed amplitudes. Next we speculate about the potential role of rock storms deeper in Jupiter's atmosphere, because the rock storms' expected energy scales make them promising candidates to be the chief source of excitation for Jovian seismic modes, based on simple scaling arguments. We also suggest some general trends in the expected partition of energy between different frequency modes. Finally we supply some commentary on potential applications to gravity, Juno, Cassini and Saturn, and future missions to Uranus and Neptune.

  19. Excitation equilibria in plasmas; a classification

    International Nuclear Information System (INIS)

    Mullen, J.A.M. van der

    1990-01-01

    This review gives a classification of the excitation kinetics ruled by electrons in plasmas. It is a study on the atomic state distribution function (ASDF) and its relation with underlying processes, which, for the case of an electron excitation kinetics (EEK) plasma, is merely a competition between free and bound electrons, the same particles in different circumstances. In a quasi steady state the population density of an atomic state results from production-destruction balances in equilibrium. If all balances are proper, i.e., consist of each other's inverse processes, then the ASDF is described by the Boltzmann-Saha relation. In other cases the balance will be denoted as improper, the ASDF will deviate from the equilibrium shape, but reflecting the underlying improper balances, it may give information about the plasma. Four improper balances and their impact on the ASDF are dealt with. An important feature is that improper balances are associated with particle transport. Special attention is paid to the distribution function of the excitation saturation balance in which the overpopulated bound electrons are subjected to frequent interactions with free electrons and the energy distribution of the free electrons is taken over. This distribution, denoted as the bound Maxwell distribution, is experimentally found in several ionizing plasmas. Its recombining counterpart, the deexcitation saturation balance, creates under certain conditions inversion in the ASDF, the basis for the recombination laser. (orig.)

  20. Isoscalar spin excitation in 40Ca

    International Nuclear Information System (INIS)

    Morlet, M.; Willis, A.; Van de Wiele, J.; Marty, N.; Johnson, B.N.; Bimbot, L.; Guillot, J.; Jourdan, F.; Langevin-Joliot, H.; Rosier, L.; Glashausser, C.; Beatty, D.; Edwards, G.W.R.; Green, A.; Djalali, C.; Youn, M.Y.

    1992-01-01

    A signature S d y of isoscalar spin-transfer strength has been tested in the inelastic scattering of 400 MeV deuterons from 12 C. It was then applied to the study of 40 Ca over an angular range from 3 deg to 7 deg (momentum transfer range from 0.26 to 0.8 fm -1 ) and an excitation energy range from 6.25 to 42 MeV. This is the first study of isoscalar spin strength in the continuum. Spin excitations were found in the 9 MeV region, and over a broad range in the continuum with a cluster of strength around 15 MeV. The results are compared with spin-flip probability measurements in proton scattering. In contrast to the total relative spin response, which is strongly enhanced at high excitation, the isoscalar relative spin response is roughly consistent with non interacting Fermi gas values. (authors) 39 refs., 13 figs., 1 tab

  1. Spin-polarized spin excitation spectroscopy

    International Nuclear Information System (INIS)

    Loth, Sebastian; Lutz, Christopher P; Heinrich, Andreas J

    2010-01-01

    We report on the spin dependence of elastic and inelastic electron tunneling through transition metal atoms. Mn, Fe and Cu atoms were deposited onto a monolayer of Cu 2 N on Cu(100) and individually addressed with the probe tip of a scanning tunneling microscope. Electrons tunneling between the tip and the substrate exchange energy and spin angular momentum with the surface-bound magnetic atoms. The conservation of energy during the tunneling process results in a distinct onset threshold voltage above which the tunneling electrons create spin excitations in the Mn and Fe atoms. Here we show that the additional conservation of spin angular momentum leads to different cross-sections for spin excitations depending on the relative alignment of the surface spin and the spin of the tunneling electron. For this purpose, we developed a technique for measuring the same local spin with a spin-polarized and a non-spin-polarized tip by exchanging the last apex atom of the probe tip between different transition metal atoms. We derive a quantitative model describing the observed excitation cross-sections on the basis of an exchange scattering process.

  2. Synchro-betatron resonance excitation in LEP

    International Nuclear Information System (INIS)

    Myers, S.

    1987-01-01

    The excitation of synchrotro-betatron resonances due to spurious dispersion and induced transverse deflecting fields at the RF cavities has been simulated for the LEP storage ring. These simulations have been performed for various possible modes of operation. In particular, a scenario has been studied in which LEP is operated at the maximum possible value of the synchrotron tune throughout the acceleration cycle, in an attempt to maximise the threshold intensity at which the Transverse Mode Coupling Instability (TMCI) occurs. This mode of operation necessitates the crossing of synchro-betatron resonances at some points in the acceleration cycle if low order non-linear machine resonances are to be avoided. Simulations have been performed in which the machine tune is swept across these synchro-betratron resonances at a rate given by the bandwidth of the magnet plus power supply circuits of the main quadrupole chain. The effect of longitudinal and transverse wake-fields on the excitation of these resonances has been investigated. These studies indicate that the distortion of the RF potential well caused by the longitudinal wake fields increases the non-linear content of the synchrotron motion and consequently increases significantly the excitation of the higher order synchro-betatron resonances

  3. Atomic collisions research with excited atomic species

    International Nuclear Information System (INIS)

    Hoogerland, M.D.; Gulley, R.J.; Colla, M.; Lu, W.; Milic, D.; Baldwin, K.G.H.; Buckman, S.J.

    1999-01-01

    Measurements and calculations of fundamental atomic collision and spectroscopic properties such as collision cross sections, reaction rates, transition probabilities etc. underpin the understanding and operation of many plasma and gas-discharge-based devices and phenomena, for example plasma processing and deposition. In almost all cases the complex series of reactions which sustains the discharge or plasma, or produces the reactive species of interest, has a precursor electron impact excitation, attachment, dissociation or ionisation event. These processes have been extensively studied in a wide range of atomic and molecular species and an impressive data base of collision cross sections and reaction rates now exists. However, most of these measurements are for collisions with stable atomic or molecular species which are initially in their ground electronic state. Relatively little information is available for scattering from excited states or for scattering from unstable molecular radicals. Examples of such species would be metastable excited rare gases, which are often used as buffer gases, or CF 2 radicals formed by electron impact dissociation in a CF 4 plasma processing discharge. We are interested in developing experimental techniques which will enable the quantitative study of such exotic atomic and molecular species. In this talk I would like to outline one such facility which is being used for studies of collisions with metastable He(2 3 S) atoms

  4. Electrically Excited Plasmonic Nanoruler for Biomolecule Detection.

    Science.gov (United States)

    Dathe, André; Ziegler, Mario; Hübner, Uwe; Fritzsche, Wolfgang; Stranik, Ondrej

    2016-09-14

    Plasmon-based sensors are excellent tools for a label-free detection of small biomolecules. An interesting group of such sensors are plasmonic nanorulers that rely on the plasmon hybridization upon modification of their morphology to sense nanoscale distances. Sensor geometries based on the interaction of plasmons in a flat metallic layer together with metal nanoparticles inherit unique advantages but need a special optical excitation configuration that is not easy to miniaturize. Herein, we introduce the concept of nanoruler excitation by direct, electrically induced generation of surface plasmons based on the quantum shot noise of tunneling currents. An electron tunneling junction consisting of a metal-dielectric-semiconductor heterostructure is directly incorporated into the nanoruler basic geometry. With the application of voltage on this modified nanoruler, the plasmon modes are directly excited without any additional optical component as a light source. We demonstrate via several experiments that this electrically driven nanoruler possesses similar properties as an optically exited one and confirm its sensing capabilities by the detection of the binding of small biomolecules such as antibodies. This new sensing principle could open the way to a new platform of highly miniaturized, integrated plasmonic sensors compatible with monolithic integrated circuits.

  5. Excitation and decay of correlated atomic states

    International Nuclear Information System (INIS)

    Rau, A.R.P.

    1992-01-01

    Doubly excited states of atoms and ions in which two electrons are excited from the ground configuration display strong radial and angular electron correlations. They are prototypical examples of quantum-mechanical systems with strong coupling. Two distinguishing characteristics of these states are: (1) their organization into successive families, with only weak coupling between families, and (2) a hierarchical nature of this coupling, with states from one family decaying primarily to those in the next lower family. A view of the pair of electrons as a single entity, with the electron-electron repulsion between them divided into a adiabatic and nonadiabatic piece, accounts for many of the dominant features. The stronger, adiabatic part determines the family structure and the weaker, nonadiabatic part the excitation and decay between successive families. Similar considerations extend to three-electron atomic states, which group into five different classes. They are suggestive of composite models for quarks in elementary particle physics, which exhibit analogous groupings into families with a hierarchical arrangement of masses and electroweak decays. 49 refs., 6 figs., 2 tabs

  6. Picosecond excitation transport in disordered systems

    International Nuclear Information System (INIS)

    Hart, D.E.

    1987-11-01

    Time-resolved fluorescence decay profiles are used to study excitation transport in 2- and 3-dimensional disordered systems. Time-correlated single photon counting detection is used to collect the fluorescence depolarization data. The high signal-to-noise ratios afforded by this technique makes it possible to critically examine current theories of excitation transport. Care has been taken to eliminate or account for the experimental artifacts common to this type of study. Solutions of 3,3'-diethyloxadicarbocyanine iodide (DODCI) in glycerol serve as a radomly distributed array of energy donors in 3-dimensions. A very thin sample cell (/approximately/ 2 μm) is used to minimize the effects of fluorescence self-absorption on the decay kinetics. Evidence of a dynamic shift of the fluorescence spectrum of DODCI in glycerol due to solvent reorganization is presented. The effects of excitation trapping on the decay profiles is minimized in the data analysis procedure. The 3-body theory of Gochanour, Andersen, and Fayer (GAF) and the far less complex 2-particle analytic theory of Huber, Hamilton, and Barnett yield indistinguishable fits to the data over the wide dynamic range of concentrations and decay times studied

  7. Thermal Excitation System for Shearography (TESS)

    Science.gov (United States)

    Lansing, Matthew D.; Bullock, Michael W.

    1996-01-01

    One of the most convenient and effective methods of stressing a part or structure for shearographic evaluation is thermal excitation. This technique involves heating the part, often convectively with a heat gun, and then monitoring with a shearography device the deformation during cooling. For a composite specimen, unbonds, delaminations, inclusions, or matrix cracking will deform during cooling differently than other more structurally sound regions and thus will appear as anomalies in the deformation field. However, one of the difficulties that cause this inspection to be dependent on the operator experience is the conventional heating process. Fanning the part with a heat gun by hand introduces a wide range of variability from person to person and from one inspection to the next. The goal of this research effort was to conduct research in the methods of thermal excitation for shearography inspection. A computerized heating system was developed for inspection of 0.61 m (24 in.) square panels. The Thermal Excitation System for Shearography (TESS) provides radiant heating with continuous digital measurement of the surface temperature profile to ensure repeatability. The TESS device functions as an accessory to any electronic shearography device.

  8. Energy harvesting by dynamic unstability and internal resonance for piezoelectric beam

    Energy Technology Data Exchange (ETDEWEB)

    Lan, Chunbo; Qin, Weiyang, E-mail: 353481781@qq.com; Deng, Wangzheng [Department of Engineering Mechanics, Northwestern Polytechnical University, Xi' an 710072 (China)

    2015-08-31

    We investigated the energy harvesting of a vertical beam with tip mass under vertical excitations. We applied dynamic unstability and internal resonance to improve the efficiency of harvesting. The experiments of harmonic excitation were carried out. Results show that for the beam there exist internal resonances in the dynamically unstable and the buckling bistable cases. The dynamic unstability is a determinant for strong internal resonance or mode coupling, which can be used to create a large output from piezoelectric patches. Then, the experiments of stochastic excitation were carried out. Results prove that the internal resonance or mode coupling can transfer the excitation energy to the low order modes, mainly the first and the second one. This can bring about a large output voltage. For a stochastic excitation, it is proved that there is an optimal weight of tip mass for realizing internal resonance and producing large outputs.

  9. Excited state non-adiabatic dynamics of N-methylpyrrole: A time-resolved photoelectron spectroscopy and quantum dynamics study

    International Nuclear Information System (INIS)

    Wu, Guorong; Neville, Simon P.; Schalk, Oliver; Sekikawa, Taro; Ashfold, Michael N. R.; Worth, Graham A.; Stolow, Albert

    2016-01-01

    The dynamics of N-methylpyrrole following excitation at wavelengths in the range 241.5-217.0 nm were studied using a combination of time-resolved photoelectron spectroscopy (TRPES), ab initio quantum dynamics calculations using the multi-layer multi-configurational time-dependent Hartree method, as well as high-level photoionization cross section calculations. Excitation at 241.5 and 236.2 nm results in population of the A 2 (πσ ∗ ) state, in agreement with previous studies. Excitation at 217.0 nm prepares the previously neglected B 1 (π3p y ) Rydberg state, followed by prompt internal conversion to the A 2 (πσ ∗ ) state. In contrast with the photoinduced dynamics of pyrrole, the lifetime of the wavepacket in the A 2 (πσ ∗ ) state was found to vary with excitation wavelength, decreasing by one order of magnitude upon tuning from 241.5 nm to 236.2 nm and by more than three orders of magnitude when excited at 217.0 nm. The order of magnitude difference in lifetimes measured at the longer excitation wavelengths is attributed to vibrational excitation in the A 2 (πσ ∗ ) state, facilitating wavepacket motion around the potential barrier in the N–CH 3 dissociation coordinate

  10. Excited state non-adiabatic dynamics of N-methylpyrrole: A time-resolved photoelectron spectroscopy and quantum dynamics study

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Guorong [National Research Council Canada, 100 Sussex Drive, Ottawa, Ontario K1A 0R6 (Canada); State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, Liaoning 116023 (China); Synergetic Innovation Center of Quantum Information & Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026 (China); Neville, Simon P. [Department of Chemistry, University of Ottawa, 10 Marie Curie, Ottawa, Ontario K1N 6N5 (Canada); Schalk, Oliver [National Research Council Canada, 100 Sussex Drive, Ottawa, Ontario K1A 0R6 (Canada); Department of Physics, AlbaNova University Center, Stockholm University, Roslagstullsbacken 21, 106 91 Stockholm (Sweden); Sekikawa, Taro [Department of Applied Physics, Hokkaido University, Kita-13 Nishi-8, Kita-ku, Sapporo 060-8628 (Japan); Ashfold, Michael N. R. [School of Chemistry, University of Bristol, Bristol BS8 1TS (United Kingdom); Worth, Graham A. [School of Chemistry, University of Birmingham, Edgbaston, Birmingham B15 2TT (United Kingdom); Stolow, Albert, E-mail: astolow@uottawa.ca [National Research Council Canada, 100 Sussex Drive, Ottawa, Ontario K1A 0R6 (Canada); Department of Chemistry, University of Ottawa, 10 Marie Curie, Ottawa, Ontario K1N 6N5 (Canada); Department of Physics, University of Ottawa, 150 Louis Pasteur, Ottawa, Ontario K1N 6N5 (Canada)

    2016-01-07

    The dynamics of N-methylpyrrole following excitation at wavelengths in the range 241.5-217.0 nm were studied using a combination of time-resolved photoelectron spectroscopy (TRPES), ab initio quantum dynamics calculations using the multi-layer multi-configurational time-dependent Hartree method, as well as high-level photoionization cross section calculations. Excitation at 241.5 and 236.2 nm results in population of the A{sub 2}(πσ{sup ∗}) state, in agreement with previous studies. Excitation at 217.0 nm prepares the previously neglected B{sub 1}(π3p{sub y}) Rydberg state, followed by prompt internal conversion to the A{sub 2}(πσ{sup ∗}) state. In contrast with the photoinduced dynamics of pyrrole, the lifetime of the wavepacket in the A{sub 2}(πσ{sup ∗}) state was found to vary with excitation wavelength, decreasing by one order of magnitude upon tuning from 241.5 nm to 236.2 nm and by more than three orders of magnitude when excited at 217.0 nm. The order of magnitude difference in lifetimes measured at the longer excitation wavelengths is attributed to vibrational excitation in the A{sub 2}(πσ{sup ∗}) state, facilitating wavepacket motion around the potential barrier in the N–CH{sub 3} dissociation coordinate.

  11. Charge transfer excitations from excited state Hartree-Fock subsequent minimization scheme

    International Nuclear Information System (INIS)

    Theophilou, Iris; Tassi, M.; Thanos, S.

    2014-01-01

    Photoinduced charge-transfer processes play a key role for novel photovoltaic phenomena and devices. Thus, the development of ab initio methods that allow for an accurate and computationally inexpensive treatment of charge-transfer excitations is a topic that nowadays attracts a lot of scientific attention. In this paper we extend an approach recently introduced for the description of single and double excitations [M. Tassi, I. Theophilou, and S. Thanos, Int. J. Quantum Chem. 113, 690 (2013); M. Tassi, I. Theophilou, and S. Thanos, J. Chem. Phys. 138, 124107 (2013)] to allow for the description of intermolecular charge-transfer excitations. We describe an excitation where an electron is transferred from a donor system to an acceptor one, keeping the excited state orthogonal to the ground state and avoiding variational collapse. These conditions are achieved by decomposing the space spanned by the Hartree-Fock (HF) ground state orbitals into four subspaces: The subspace spanned by the occupied orbitals that are localized in the region of the donor molecule, the corresponding for the acceptor ones and two more subspaces containing the virtual orbitals that are localized in the neighborhood of the donor and the acceptor, respectively. Next, we create a Slater determinant with a hole in the subspace of occupied orbitals of the donor and a particle in the virtual subspace of the acceptor. Subsequently we optimize both the hole and the particle by minimizing the HF energy functional in the corresponding subspaces. Finally, we test our approach by calculating the lowest charge-transfer excitation energies for a set of tetracyanoethylene-hydrocarbon complexes that have been used earlier as a test set for such kind of excitations

  12. The [NeIV] Lines in High Excitation Gaseous Nebulae.

    Science.gov (United States)

    Aller, L H

    1970-04-01

    The "forbidden" lines of three times ionized neon are among the most precious indicators of electron temperature and excitation. They are also predicted to be among the strongest lines observed in the far ultraviolet spectra of high excitation nebulae.

  13. Electromagnetic radiation of ultrarelativistic particles at scattering in excited medium

    International Nuclear Information System (INIS)

    Malyshevskij, V.S.

    1990-01-01

    The interaction between relativistic particles and a gaseous or condensed medium with a high density of nondegenerate excited quantum states involves the coherent conversion of atomic or molecular excitations into electromagnetic radiation

  14. Impact self-excited vibrations of linear motor

    Science.gov (United States)

    Zhuravlev, V. Ph.

    2010-08-01

    Impact self-exciting vibration modes in a linear motor of a monorail car are studied. Existence and stability conditions of self-exciting vibrations are found. Ways of avoiding the vibrations are discussed.

  15. Properties of excited xenon atoms in a plasma display panel

    International Nuclear Information System (INIS)

    Uhm, Han S.; Hong, Byoung H.; Oh, Phil Y.; Choi, Eun H.

    2009-01-01

    The luminance efficiency of a plasma display panel is directly related to the vacuum ultraviolet (VUV) light that is emitted from excited xenon (Xe) atoms and molecules. It is therefore necessary to investigate the properties of excited xenon atoms. This study presents experimental data associated with the behavior of excited xenon atoms in a PDP discharge cell and compares the data with the theoretical results obtained using an analytical model. The properties of excited xenon atoms in the discharge cells of a plasma display panel are investigated by measuring the excited atom density through the use of laser absorption spectroscopy. The density of the excited xenon atoms increases from zero, reaches its peak, and decreases with time in the discharge cells. The profile of the excited xenon atoms is also studied in terms of the xenon mole fraction. The typical density of the excited xenon atoms in the metastable state is on the order of 10 13 atoms per cubic cm.

  16. Efficient primary and parametric resonance excitation of bistable resonators

    KAUST Repository

    Ramini, Abdallah; Alcheikh, Nouha; Ilyas, Saad; Younis, Mohammad I.

    2016-01-01

    efficient and requires less power for primary resonance excitation. Moreover, unlike the classical method where the structure is vulnerable to the dynamic pull-in instability, the axial excitation technique can provide large amplitude motion while protecting

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

    International Nuclear Information System (INIS)

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

    2015-01-01

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

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

    Science.gov (United States)

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

    2015-06-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

    Elkins, Madeline H.; Williams, Holly L. [Department of Chemistry, University of California, Berkeley, California 94720 (United States); Neumark, Daniel M. [Department of Chemistry, University of California, Berkeley, California 94720 (United States); Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)

    2015-06-21

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

  20. Stac3 is a component of the excitation-contraction coupling machinery and mutated in Native American myopathy

    Science.gov (United States)

    Horstick, Eric J.; Linsley, Jeremy W.; Dowling, James J.; Hauser, Michael A.; McDonald, Kristin K.; Ashley-Koch, Allison; Saint-Amant, Louis; Satish, Akhila; Cui, Wilson W.; Zhou, Weibin; Sprague, Shawn M.; Stamm, Demetra S.; Powell, Cynthia M.; Speer, Marcy C.; Franzini-Armstrong, Clara; Hirata, Hiromi; Kuwada, John Y.

    2013-01-01

    Excitation-contraction coupling, the process that regulates contractions by skeletal muscles, transduces changes in membrane voltage by activating release of Ca2+ from internal stores to initiate muscle contraction. Defects in EC coupling are associated with muscle diseases. Here we identify Stac3 as a novel component of the EC coupling machinery. Using a zebrafish genetic screen, we generate a locomotor mutation that is mapped to stac3. We provide electrophysiological, Ca2+ imaging, immunocytochemical and biochemical evidence that Stac3 participates in excitation-contraction coupling in muscles. Furthermore, we reveal that a mutation in human STAC3 as the genetic basis of the debilitating Native American myopathy (NAM). Analysis of NAM stac3 in zebrafish shows that the NAM mutation decreases excitation-contraction coupling. These findings enhance our understanding of both excitation-contraction coupling and the pathology of myopathies. PMID:23736855