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....

"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.

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

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.

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.

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.

Communication: State-to-state dynamics of the Cl + H2O → HCl + OH reaction: Energy flow into reaction coordinate and transition-state control of product energy disposal.

Science.gov (United States)

Zhao, Bin; Sun, Zhigang; Guo, Hua

2015-06-28

Quantum state-to-state dynamics of a prototypical four-atom reaction, namely, Cl + H2O → HCl + OH, is investigated for the first time in full dimensionality using a transition-state wave packet method. The state-to-state reactivity and its dependence on the reactant internal excitations are analyzed and found to share many similarities both energetically and dynamically with the H + H2O → H2 + OH reaction. The strong enhancement of reactivity by the H2O stretching vibrational excitations in both reactions is attributed to the favorable energy flow into the reaction coordinate near the transition state. On the other hand, the insensitivity of the product state distributions with regard to reactant internal excitation stems apparently from the transition-state control of product energy disposal.

Communication: State-to-state dynamics of the Cl + H2O → HCl + OH reaction: Energy flow into reaction coordinate and transition-state control of product energy disposal

International Nuclear Information System (INIS)

Zhao, Bin; Guo, Hua; Sun, Zhigang

2015-01-01

Quantum state-to-state dynamics of a prototypical four-atom reaction, namely, Cl + H 2 O → HCl + OH, is investigated for the first time in full dimensionality using a transition-state wave packet method. The state-to-state reactivity and its dependence on the reactant internal excitations are analyzed and found to share many similarities both energetically and dynamically with the H + H 2 O → H 2 + OH reaction. The strong enhancement of reactivity by the H 2 O stretching vibrational excitations in both reactions is attributed to the favorable energy flow into the reaction coordinate near the transition state. On the other hand, the insensitivity of the product state distributions with regard to reactant internal excitation stems apparently from the transition-state control of product energy disposal

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.

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

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

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.

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.

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.

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.

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.

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

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.

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.

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.

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...

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.

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.

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.

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.

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.

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.

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.

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

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.

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....

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.)

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....

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

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.

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.

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.

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.

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

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.

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)

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.

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

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…

Journal of Chemical Sciences | Indian Academy of Sciences

Indian Academy of Sciences (India)

Excited state intramolecular charge transfer reaction of 4-(morpholenyl) benzonitrile in solution: Effects ... in (mixed solvent + electrolyte) systems: Role of reactant-solvent and reactant-ion interactions .... A molecular dynamics simulation study.

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.

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.

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.

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.

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.

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.

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

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

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.

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.

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.

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

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.

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.

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.

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...

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

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)

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.

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

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.

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.

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

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.

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.

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...

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.

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.

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.

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.

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)

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.

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.

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.

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

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)

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

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

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

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.)

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.

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.

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.

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.

Spatially Localized Chemical Patterns around an A + B → Oscillator Front.

Science.gov (United States)

Budroni, M A; Lemaigre, L; Escala, D M; Muñuzuri, A P; De Wit, A

2016-02-18

When two gels, each loaded with a different set of reactants A and B of an oscillatory reaction, are brought into contact, reaction-diffusion patterns such as waves or Turing patterns can develop in the reactive contact zone. The initial condition which separates the reactants at the beginning leads to a localization in space of the different dynamical regimes accessible to the chemical oscillator. We study here both numerically and experimentally the composite traveling structures resulting from the interaction between chemical fronts and localized waves in the case in which the reactants of such an A + B → oscillator system are those of the canonical Belousov-Zhabotinsky (BZ) oscillating reaction. A transition between different dynamics is obtained by varying the initial concentration of the organic substrate of the BZ reactants, which is one of the parameters controlling the local excitability. We show that the dynamical regime (excitable or oscillatory) characterizing the BZ oscillator in the initial contact area is the key feature which determines the spatiotemporal evolution of the system. The experimental results are in qualitative agreement with the theoretical predictions.

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.

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.

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

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.

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

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.

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.

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.

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)

Quasiclassical trajectory studies of the O(3P) + CX4(vk = 0, 1) → OXv + CX3(n1n2n3n4) [X = H and D] reactions on an ab initio potential energy surface.

Science.gov (United States)

Czakó, Gábor; Liu, Rui; Yang, Minghui; Bowman, Joel M; Guo, Hua

2013-08-01

We report quasiclassical trajectory calculations of the integral and differential cross sections and the mode-specific product state distributions for the "central-barrier" O((3)P) + CH4/CD4(vk = 0, 1) [k = 1, 2, 3, 4] reactions using a full-dimensional ab initio potential energy surface. The mode-specific vibrational distributions for the polyatomic methyl products are obtained by doing a normal-mode analysis in the Eckart frame, followed by standard histogram binning (HB) and energy-based Gaussian binning (1GB). The reactant bending excitations slightly enhance the reactivity, whereas stretching excitations activate the reaction more efficiently. None of the reactant vibrational excitations is as efficient as an equivalent amount of translational energy to promote the reactions. The excitation functions without product zero-point energy (ZPE) constraint are in good agreement with previous 8-dimensional quantum mechanical (QM) results for the ground-state and stretching-excited O + CH4 reactions, whereas for the bending-excited reactions the soft ZPE constraint, which is applied to the sum of the product vibrational energies, provides better agreement with the QM cross sections. All angular distributions show the dominance of backward scattering indicating a direct rebound mechanism, in agreement with experiment. The title reactions produce mainly OH/OD(v = 0) products for all the initial states. HB significantly overestimates the populations of OH/OD(v = 1), especially in the energetic threshold regions, whereas 1GB provides physically correct results. The CH3/CD3 vibrational distributions show dominant populations for ground (v = 0), umbrella-excited (v2 = 1, 2), in-plane-bending-excited (v4 = 1), and v2 + v4 methyl product states. Neither translational energy nor reactant vibrational excitation transfers significantly into product vibrations.

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

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.

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

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...

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.

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.

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.

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

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

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

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.

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

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

A seismic analysis of nuclear power plant components subjected to multi-excitations of earthquakes

International Nuclear Information System (INIS)

Ichiki, T.; Matsumoto, T.; Gunyasu, K.

1977-01-01

In this analysis, the modal analysis methods are used to determine the seismic responses of structural systems instead of the direct integration method. These results have been compared with some kinds of other analytical methods, and investigated the accuracy of numerical results of these analysis, applying to such components as Reactor Pressure Vessel and Reactor Internals of an actual plant. The results of this method of analysis are summarized as follows: (1) one of the seismic analysis methods concerning systems subjected to multi-excitations of earthquakes has been presented to the conference of JSME. Although the analytical theory presented to that conference is correct, it has a serious problem about the accuracy of numerical results. This computer program and theory cannot be used practically due to the time necessary to calculate. However, the method described in this paper overcomes those serious problems stated above and has no problem about the computer time and precision. So, it is possible to apply this method to the seismic design of an actual nuclear power plant practically. (2) The feed back effects of the seismic responses of Reactor Internals to Reactor Building are considered so small that we can separate the model of Reactor Internals from Reactor Building. (3) The results of seismic response of Reactor Internals are fairly consistent with those obtained from the model coupled with Reactor Building. (4) This analysis method can be extended to the model of Reactor Internals subjected to more than two random excitations of earthquakes. (5) It is possible that this analysis method is also applied to the seismic analysis of such three-dimensional systems as piping systems subjected to multi-excitations of earthquakes

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.

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.

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

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...

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

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

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.

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

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

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 ...

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

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...

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.

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.

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)

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.

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 ...

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

An unavoidable modulation? Sensory attention and human primary motor cortex excitability.

Science.gov (United States)

Ruge, Diane; Muggleton, Neil; Hoad, Damon; Caronni, Antonio; Rothwell, John C

2014-09-01

The link between basic physiology and its modulation by cognitive states, such as attention, is poorly understood. A significant association becomes apparent when patients with movement disorders describe experiences with changing their attention focus and the fundamental effect that this has on their motor symptoms. Moreover, frequently used mental strategies for treating such patients, e.g. with task-specific dystonia, widely lack laboratory-based knowledge about physiological mechanisms. In this largely unexplored field, we looked at how the locus of attention, when it changed between internal (locus hand) and external (visual target), influenced excitability in the primary motor cortex (M1) in healthy humans. Intriguingly, both internal and external attention had the capacity to change M1 excitability. Both led to a reduced stimulation-induced GABA-related inhibition and a change in motor evoked potential size, i.e. an overall increased M1 excitability. These previously unreported findings indicated: (i) that cognitive state differentially interacted with M1 physiology, (ii) that our view of distraction (attention locus shifted towards external or distant location), which is used as a prevention or management strategy for use-dependent motor disorders, is too simple and currently unsupported for clinical application, and (iii) the physiological state reached through attention modulation represents an alternative explanation for frequently reported electrophysiology findings in neuropsychiatric disorders, such as an aberrant inhibition. © 2014 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.

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.

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

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.

Lattice Boltzmann simulation for the energy and entropy of excitable systems

Institute of Scientific and Technical Information of China (English)

Deng Min-Yi; Tang Guo-Ning; Kong Ling-Jiang; Liu Mu-Ren

2011-01-01

The internal energy and the spatiotemporal entropy of excitable systems are investigated with the lattice Boltzmann method. The numerical results show that the breakup of spiral wave is attributed to the inadequate supply of energy, i.e., the internal energy of system is smaller than the energy of self-sustained spiral wave. It is observed that the average internal energy of a regular wave state reduces with its spatiotemporal entropy decreasing. Interestingly, although the energy difference between two regular wave states is very small, the different states can be distinguished obviously due to the large difference between their spatiotemporal entropies. In addition, when the unstable spiral wave converts into the spatiotemporal chaos, the internal energy of system decreases, while the spatiotemporal entropy increases, which behaves as the thermodynamic entropy in an isolated system.

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

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.

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.

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

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.

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

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

Atom-radical reaction dynamics of O(3P)+C3H5→C3H4+OH: Nascent rovibrational state distributions of product OH

Science.gov (United States)

Park, Jong-Ho; Lee, Hohjai; Kwon, Han-Cheol; Kim, Hee-Kyung; Choi, Young-Sang; Choi, Jong-Ho

2002-08-01

The reaction dynamics of ground-state atomic oxygen [O(3P)] with allyl radicals (C3H5) has been investigated by applying a combination of crossed beams and laser induced fluorescence techniques. The reactants O(3P) and C3H5 were produced by the photodissociation of NO2 and the supersonic flash pyrolysis of precursor allyl iodide, respectively. A new exothermic channel of O(3P)+C3H5→C3H4+OH was observed and the nascent internal state distributions of the product OH (X 2Π:υ″=0,1) showed substantial bimodal internal excitations of the low- and high-N″ components without Λ-doublet and spin-orbit propensities in the ground and first excited vibrational states. With the aid of the CBS-QB3 level of ab initio theory and Rice-Ramsperger-Kassel-Marcus calculations, it is predicted that on the lowest doublet potential energy surface the major reaction channel of O(3P) with C3H5 is the formation of acrolein (CH2CHCHO)+H, which is consistent with the previous bulk kinetic experiments performed by Gutman et al. [J. Phys. Chem. 94, 3652 (1990)]. The counterpart C3H4 of the probed OH product in the title reaction is calculated to be allene after taking into account the factors of reaction enthalpy, barrier height and the number of intermediates involved along the reaction pathway. On the basis of population analyses and comparison with prior calculations, the statistical picture is not suitable to describe the reactive atom-radical scattering processes, and the dynamics of the title reaction is believed to proceed through two competing dynamical pathways. The major low N″-components with significant vibrational excitation may be described by the direct abstraction process, while the minor but extraordinarily hot rotational distribution of high N″-components implies that some fraction of reactants is sampled to proceed through the indirect short-lived addition-complex forming process.

Internal quantum efficiency enhancement of GaInN/GaN quantum-well structures using Ag nanoparticles

DEFF Research Database (Denmark)

Iida, Daisuke; Fadil, Ahmed; Chen, Yuntian

2015-01-01

We report internal quantum efficiency enhancement of thin p-GaN green quantumwell structure using self-assembled Ag nanoparticles. Temperature dependent photoluminescence measurements are conducted to determine the internal quantum efficiency. The impact of excitation power density on the enhance......We report internal quantum efficiency enhancement of thin p-GaN green quantumwell structure using self-assembled Ag nanoparticles. Temperature dependent photoluminescence measurements are conducted to determine the internal quantum efficiency. The impact of excitation power density...

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.

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

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.

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.

State-to-State Mode Specificity: Energy Sequestration and Flow Gated by Transition State.

Science.gov (United States)

Zhao, Bin; Sun, Zhigang; Guo, Hua

2015-12-23

Energy flow and sequestration at the state-to-state level are investigated for a prototypical four-atom reaction, H2 + OH → H + H2O, using a transition-state wave packet (TSWP) method. The product state distribution is found to depend strongly on the reactant vibrational excitation, indicating mode specificity at the state-to-state level. From a local-mode perspective, it is shown that the vibrational excitation of the H2O product derives from two different sources, one attributable to the energy flow along the reaction coordinate into the newly formed OH bond and the other due to the sequestration of the vibrational energy in the OH spectator moiety during the reaction. The analysis provided a unified interpretation of some seemingly contradicting experimental observations. It is further shown that the transfer of vibrational energy from the OH reactant to H2O product is gated by the transition state, accomplished coherently by multiple TSWPs with the corresponding OH vibrational excitation.

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

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.

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)

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

Optical near-field studies of waveguiding organic nanofibers by angular dependent excitation

DEFF Research Database (Denmark)

Maibohm, Christian

.                    2) Institute of General Physics, Russian Academy of Science, 119991 Moscow, Russia. Abstract:   Single crystalline organic nanofibers of para-phenylene are grown in UHV by MBE and dipole assisted self-assembly. In the optical far-field the fluorescence from a single nanofiber is spectrally well...... defined and highly polarized. By UV excitation in a fluorescence microscope it has also been shown that nanofibers have waveguiding properties. To further characterize the waveguiding properties the optical near-field has to be investigated. This is done by transferring nanofibers to an quartz half sphere...... where they are excited by the evanescent wave from a total internal reflected UV laser. The optical near-field is probed by the fiber tip of a SNOM (scanning near-field optical microscope). In the setup it is possible to change the angle of incidence of the excitation laser i.e. change the k...

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

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.)

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

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.

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.

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.

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

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

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

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

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.

Surface plasmon-enhanced two-photon excited whispering-gallery modes ultraviolet laser from Zno microwire

Directory of Open Access Journals (Sweden)

Yunpeng Wang

2017-11-01

Full Text Available The two-photon excited UV laser with narrow line width and high Q value was obtained. The total internal reflection from the four side surfaces of the quadrilateral-ZnO microwire offered the whispering gallery mode (WGM resonant cavity. The UV emission, resonant mechanism, and laser mode characteristics were discussed in detail for this special type of micro-cavity. In addition, in order to enhance the power of the two-photon excited UV laser, the surface plasmon enhancement by the Au nanoparticles was also performed and explained well by the theory of the localized surface plasmon.

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.

Generative complexity of Gray-Scott model

Science.gov (United States)

Adamatzky, Andrew

2018-03-01

In the Gray-Scott reaction-diffusion system one reactant is constantly fed in the system, another reactant is reproduced by consuming the supplied reactant and also converted to an inert product. The rate of feeding one reactant in the system and the rate of removing another reactant from the system determine configurations of concentration profiles: stripes, spots, waves. We calculate the generative complexity-a morphological complexity of concentration profiles grown from a point-wise perturbation of the medium-of the Gray-Scott system for a range of the feeding and removal rates. The morphological complexity is evaluated using Shannon entropy, Simpson diversity, approximation of Lempel-Ziv complexity, and expressivity (Shannon entropy divided by space-filling). We analyse behaviour of the systems with highest values of the generative morphological complexity and show that the Gray-Scott systems expressing highest levels of the complexity are composed of the wave-fragments (similar to wave-fragments in sub-excitable media) and travelling localisations (similar to quasi-dissipative solitons and gliders in Conway's Game of Life).

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.

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.

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

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

Operational production of Geodetic Excitation Functions from EOP estimated values at ASI-CGS

Science.gov (United States)

Sciarretta, C.; Luceri, V.; Bianco, G.

2009-04-01

ASI-CGS is routinely providing geodetic excitation functions from its own estimated EOP values (at present SLR and VLBI; the current use of GPS EOP's is also planned as soon as this product will be fully operational) on the ASI geodetic web site (http://geodaf.mt.asi.it). This product has been generated and monitored (for ASI internal use only) in a long pre-operational phase (more than two years), including validation and testing. The daily geodetic excitation functions are now weekly updated along with the operational ASI SLR and VLBI EOP solutions and compared, whenever possible, with the atmospheric excitation functions available at the IERS SBAAM, under the IB and not-IB assumption, including the "wind" term. The work will present the available estimated geodetic function time series and its comparison with the relevant atmospheric excitation functions, deriving quantitative indicators on the quality of the estimates. The similarities as well as the discrepancies among the atmospheric and geodetic series will be analysed and commented, evaluating in particular the degree of correlation among the two estimated time series and the likelihood of a linear dependence hypothesis.

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

Ionic wave propagation and collision in an excitable circuit model of microtubules

Science.gov (United States)

Guemkam Ghomsi, P.; Tameh Berinyoh, J. T.; Moukam Kakmeni, F. M.

2018-02-01

In this paper, we report the propensity to excitability of the internal structure of cellular microtubules, modelled as a relatively large one-dimensional spatial array of electrical units with nonlinear resistive features. We propose a model mimicking the dynamics of a large set of such intracellular dynamical entities as an excitable medium. We show that the behavior of such lattices can be described by a complex Ginzburg-Landau equation, which admits several wave solutions, including the plane waves paradigm. A stability analysis of the plane waves solutions of our dynamical system is conducted both analytically and numerically. It is observed that perturbed plane waves will always evolve toward promoting the generation of localized periodic waves trains. These modes include both stationary and travelling spatial excitations. They encompass, on one hand, localized structures such as solitary waves embracing bright solitons, dark solitons, and bisolitonic impulses with head-on collisions phenomena, and on the other hand, the appearance of both spatially homogeneous and spatially inhomogeneous stationary patterns. This ability exhibited by our array of proteinic elements to display several states of excitability exposes their stunning biological and physical complexity and is of high relevance in the description of the developmental and informative processes occurring on the subcellular scale.

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.

Equivalent non-Gaussian excitation method for response moment calculation of systems under non-Gaussian random excitation

International Nuclear Information System (INIS)

Tsuchida, Takahiro; Kimura, Koji

2015-01-01

Equivalent non-Gaussian excitation method is proposed to obtain the moments up to the fourth order of the response of systems under non-Gaussian random excitation. The excitation is prescribed by the probability density and power spectrum. Moment equations for the response can be derived from the stochastic differential equations for the excitation and the system. However, the moment equations are not closed due to the nonlinearity of the diffusion coefficient in the equation for the excitation. In the proposed method, the diffusion coefficient is replaced with the equivalent diffusion coefficient approximately to obtain a closed set of the moment equations. The square of the equivalent diffusion coefficient is expressed by the second-order polynomial. In order to demonstrate the validity of the method, a linear system to non-Gaussian excitation with generalized Gaussian distribution is analyzed. The results show the method is applicable to non-Gaussian excitation with the widely different kurtosis and bandwidth. (author)

3rd International Conference on Transcriptomics

OpenAIRE

John A Daniel

2017-01-01

Conference Series has been instrumental in conducting international Biochemistry meetings for seven years, and very excited to expand Europe, America and Asia Pacific continents. Previous meetings were held in major cities like Philadelphia, Orlando with success the meetings again scheduled in three continents. 3rd International Conference on Transcriptomics to be held during October 30 - November 01, 2017 at Bangkok, Thailand The Global Transcriptomics business sector to develop at a C...

Excitation of autoionizing states of helium by 100 keV proton impact: II. Excitation cross sections and mechanisms of excitation

Energy Technology Data Exchange (ETDEWEB)

Godunov, A.L. [Department of Physics, Tulane University, New Orleans, LA 70118-5698 (United States); Ivanov, P.B.; Schipakov, V.A. [Troitsk Institute of Innovation and Fusion Research Troitsk, Moscow region, 142092 (Russian Federation); Moretto-Capelle, P.; Bordenave-Montesquieu, D.; Bordenave-Montesquieu, A. [Laboratoire Collisions, Agregats, Reactivite, IRSAMC, UMR 5589, CNRS-Universite Paul Sabatier, 31062 Toulouse Cedex (France)

2000-03-14

Mechanisms of two-electron excitation of the (2s{sup 2}){sup 1} S, (2p{sup 2} ){sup 1} D and (2s2p){sup 1} P autoionizing states of helium are studied both experimentally and theoretically. It is shown that an explicit introduction of a kinematic factor, with a process-specific phase leads to a productive parametrization of experimental cross sections of ionization, allowing one to extract cross sections of excitation of autoionizing states. Using a new fitting procedure together with the proposed parametrization made it possible to obtain the excitation cross sections and magnetic sublevel population from electron spectra as well as, for the first time, to resolve the contribution of resonance and interference components to resonance profiles. Interference with direct ionization is shown to contribute significantly into resonance formation even for backward ejection angles. We demonstrate theoretically that the excitation cross sections thus extracted from experimental electron spectra hold information about the interaction of autoionizing states with an adjacent continuum. (author)

A z-gradient array for simultaneous multi-slice excitation with a single-band RF pulse.

Science.gov (United States)

Ertan, Koray; Taraghinia, Soheil; Sadeghi, Alireza; Atalar, Ergin

2018-07-01

Multi-slice radiofrequency (RF) pulses have higher specific absorption rates, more peak RF power, and longer pulse durations than single-slice RF pulses. Gradient field design techniques using a z-gradient array are investigated for exciting multiple slices with a single-band RF pulse. Two different field design methods are formulated to solve for the required current values of the gradient array elements for the given slice locations. The method requirements are specified, optimization problems are formulated for the minimum current norm and an analytical solution is provided. A 9-channel z-gradient coil array driven by independent, custom-designed gradient amplifiers is used to validate the theory. Performance measures such as normalized slice thickness error, gradient strength per unit norm current, power dissipation, and maximum amplitude of the magnetic field are provided for various slice locations and numbers of slices. Two and 3 slices are excited by a single-band RF pulse in simulations and phantom experiments. The possibility of multi-slice excitation with a single-band RF pulse using a z-gradient array is validated in simulations and phantom experiments. Magn Reson Med 80:400-412, 2018. © 2017 International Society for Magnetic Resonance in Medicine. © 2017 International Society for Magnetic Resonance in Medicine.

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.

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.

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

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.

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.

Supercritical Nonlinear Vibration of a Fluid-Conveying Pipe Subjected to a Strong External Excitation

Directory of Open Access Journals (Sweden)

Yan-Lei Zhang

2016-01-01

Full Text Available Nonlinear vibration of a fluid-conveying pipe subjected to a transverse external harmonic excitation is investigated in the case with two-to-one internal resonance. The excitation amplitude is in the same magnitude of the transverse displacement. The fluid in the pipes flows in the speed larger than the critical speed so that the straight configuration becomes an unstable equilibrium and two curved configurations bifurcate as stable equilibriums. The motion measured from each of curved equilibrium configurations is governed by a nonlinear integro-partial-differential equation with variable coefficients. The Galerkin method is employed to discretize the governing equation into a gyroscopic system consisting of a set of coupled nonlinear ordinary differential equations. The method of multiple scales is applied to analyze approximately the gyroscopic system. A set of first-order ordinary differential equations governing the modulations of the amplitude and the phase are derived via the method. In the supercritical regime, the subharmonic, superharmonic, and combination resonances are examined in the presence of the 2 : 1 internal resonance. The steady-state responses and their stabilities are determined. The various jump phenomena in the amplitude-frequency response curves are demonstrated. The effects of the viscosity, the excitation amplitude, the nonlinearity, and the flow speed are observed. The analytical results are supported by the numerical integration.

Vibration behavior of PWR reactor internals Model experiments and analysis

International Nuclear Information System (INIS)

Assedo, R.; Dubourg, M.; Livolant, M.; Epstein, A.

1975-01-01

In the late 1971, the CEA and FRAMATOME decided to undertake a comprehensive joint program of studying the vibration behavior of PWR internals of the 900 MWe, 50 cycle, 3 loop reactor series being built by FRAMATOME in France. The PWR reactor internals are submitted to several sources of excitation during normal operation. Two main sources of excitation may effect the internals behavior: the large flow turbulences which could generate various instabilities such as: vortex shedding: the pump pressure fluctuations which could generate acoustic noise in the circuit at frequencies corresponding to shaft speed frequencies or blade passing frequencies, and their respective harmonics. The flow induced vibrations are of complex nature and the approach selected, for this comprehensive program, is semi-empirical and based on both theoretical analysis and experiments on a reduced scale model and full scale internals. The experimental support of this program consists of: the SAFRAN test loop which consists of an hydroelastic similitude of a 1/8 scale model of a PWR; harmonic vibration tests in air performed on full scale reactor internals in the manufacturing shop; the GENNEVILLIERS facilities which is a full flow test facility of primary pump; the measurements carried out during start up on the Tihange reactor. This program will be completed in April 1975. The results of this program, the originality of which consists of studying separately the effects of random excitations and acoustic noises, on the internals behavior, and by establishing a comparison between experiments and analysis, will bring a major contribution for explaining the complex vibration phenomena occurring in a PWR

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.

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.

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.

Isomer depletion as experimental evidence of nuclear excitation by electron capture

Science.gov (United States)

Chiara, C. J.; Carroll, J. J.; Carpenter, M. P.; Greene, J. P.; Hartley, D. J.; Janssens, R. V. F.; Lane, G. J.; Marsh, J. C.; Matters, D. A.; Polasik, M.; Rzadkiewicz, J.; Seweryniak, D.; Zhu, S.; Bottoni, S.; Hayes, A. B.; Karamian, S. A.

2018-02-01

The atomic nucleus and its electrons are often thought of as independent systems that are held together in the atom by their mutual attraction. Their interaction, however, leads to other important effects, such as providing an additional decay mode for excited nuclear states, whereby the nucleus releases energy by ejecting an atomic electron instead of by emitting a γ-ray. This ‘internal conversion’ has been known for about a hundred years and can be used to study nuclei and their interaction with their electrons. In the inverse process—nuclear excitation by electron capture (NEEC)—a free electron is captured into an atomic vacancy and can excite the nucleus to a higher-energy state, provided that the kinetic energy of the free electron plus the magnitude of its binding energy once captured matches the nuclear energy difference between the two states. NEEC was predicted in 1976 and has not hitherto been observed. Here we report evidence of NEEC in molybdenum-93 and determine the probability and cross-section for the process in a beam-based experimental scenario. Our results provide a standard for the assessment of theoretical models relevant to NEEC, which predict cross-sections that span many orders of magnitude. The greatest practical effect of the NEEC process may be on the survival of nuclei in stellar environments, in which it could excite isomers (that is, long-lived nuclear states) to shorter-lived states. Such excitations may reduce the abundance of the isotope after its production. This is an example of ‘isomer depletion’, which has been investigated previously through other reactions, but is used here to obtain evidence for NEEC.

Response moments of dynamic systems under non-Gaussian random excitation by the equivalent non-Gaussian excitation method

International Nuclear Information System (INIS)

Tsuchida, Takahiro; Kimura, Koji

2016-01-01

Equivalent non-Gaussian excitation method is proposed to obtain the response moments up to the 4th order of dynamic systems under non-Gaussian random excitation. The non-Gaussian excitation is prescribed by the probability density and the power spectrum, and is described by an Ito stochastic differential equation. Generally, moment equations for the response, which are derived from the governing equations for the excitation and the system, are not closed due to the nonlinearity of the diffusion coefficient in the equation for the excitation even though the system is linear. In the equivalent non-Gaussian excitation method, the diffusion coefficient is replaced with the equivalent diffusion coefficient approximately to obtain a closed set of the moment equations. The square of the equivalent diffusion coefficient is expressed by a quadratic polynomial. In numerical examples, a linear system subjected to nonGaussian excitations with bimodal and Rayleigh distributions is analyzed by using the present method. The results show that the method yields the variance, skewness and kurtosis of the response with high accuracy for non-Gaussian excitation with the widely different probability densities and bandwidth. The statistical moments of the equivalent non-Gaussian excitation are also investigated to describe the feature of the method. (paper)

Research of the internal electron-positron pair production

International Nuclear Information System (INIS)

Fenyes, Tibor

1985-01-01

The phenomenon of internal electron-positron pair production by excited nuclei is briefly reviewed. The advantages of this phenomenon in nuclear structure investigations are pointed. The new Si(Li)-Si(Li) electron spectrometer with superconducting magnetic transporter (SMS) built at ATOMKI, Hungary, was tested for detection of internal electron-positron pair production events. Proton beam of a Van de Graaff accelerator of 5 MV was used to excite the target nuclei of sup(27)Al, sup(42)Ca and sup(19)F. The internal pair production coefficients were measured and compared with the data of literature. The detection efficiency of SMS is calculated to be (37+-7)%. The test proved that the SMS is suitable for nuclear structure investigations producing electron-positron pairs. The SMS of ATOMKI is recently the top instrument all over the world in this field: its detection efficiency, energy resolution and applicability for multipolarity identification are much better than these properties of other detectors. (D.Gy.)

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.

Transient Exciplex Formation Electron Transfer Mechanism

Directory of Open Access Journals (Sweden)

Michael G. Kuzmin

2011-01-01

Full Text Available Transient exciplex formation mechanism of excited-state electron transfer reactions is analyzed in terms of experimental data on thermodynamics and kinetics of exciplex formation and decay. Experimental profiles of free energy, enthalpy, and entropy for transient exciplex formation and decay are considered for several electron transfer reactions in various solvents. Strong electronic coupling in contact pairs of reactants causes substantial decrease of activation energy relative to that for conventional long-range ET mechanism, especially for endergonic reactions, and provides the possibility for medium reorganization concatenated to gradual charge shift in contrast to conventional preliminary medium and reactants reorganization. Experimental criteria for transient exciplex formation (concatenated mechanism of excited-state electron transfer are considered. Available experimental data show that this mechanism dominates for endergonic ET reactions and provides a natural explanation for a lot of known paradoxes of ET reactions.

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...

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

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

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...

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.

Internal standardization in atomic-emission spectrometry using inductively coupled plasma

International Nuclear Information System (INIS)

Moore, G.L.

1985-01-01

The principle of internal standardization has been used in quantitative analytical emission spectroscopy since 1925 to minimize the errors arising from fluctuations in sample preparation, excitation-source conditions, and detection parameters. Although modern spectroscopic excitation sources are far more stable and electronic detection methods are more precise than before, the system for the introduction of the sample in spectrometric analysis using inductively coupled plasma (ICP) introduces significant errors, and internal standardization can still play a useful role in improving the overall precision of the analytical results. The criteria for the selection of the elements to be used as internal standards in arc and spark spectrographic analysis apply to a much lesser extent in ICP-spectrometric analysis. Internal standardization is recommended for use in routine ICP-simultaneous spectrometric analysis to improve its accuracy and precision and to provide a monitor for the reassurance of the analyst. However, the selection of an unsuitable reference element can result in misuse of the principle of internal standardization and, although internal standardization can be applied when a sequential monochromator is used, the main sources of error will not be minimized

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 ...

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.

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....

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

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)

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

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)

Visible-Light-Mediated Excited State Relaxation in Semi-Synthetic Genetic Alphabet: d5SICS and dNaM.

Science.gov (United States)

Bhattacharyya, Kalishankar; Datta, Ayan

2017-08-25

The excited state dynamics of an unnatural base pair (UBP) d5SICS/dNaM were investigated by accurate ab-initio calculations. Time-dependent density functional and high-level multireference calculations (MS-CASPT2) were performed to elucidate the excitation of this UBP and its excited state relaxation mechanism. After excitation to the bright state S 2 (ππ*), it decays to the S 1 state and then undergoes efficient intersystem crossing to the triplet manifold. The presence of sulfur atom in d5SICS leads to strong spin-orbit coupling (SOC) and a small energy gap that facilitates intersystem crossing from S 1 (n s π*) to T 2 (ππ*) followed by internal conversion to T 1 state. Similarly in dNaM, the deactivation pathway follows analogous trends. CASPT2 calculations suggest that the S 1 (ππ*) state is a dark state below the accessible S 2 (ππ*) bright state. During the ultrafast deactivation, it exhibits bond length inversion. From S 1 state, significant SOC leads the population transfer to T 3 due to a smaller energy gap. Henceforth, fast internal conversion occurs from T 3 to T 2 followed by T 1 . From time-dependent trajectory surface hopping dynamics, it is found that excited state relaxation occurs on a sub-picosecond timescale in d5SICS and dNaM. Our findings strongly suggest that there is enough energy available in triplet state of UBP to generate reactive oxygen species and induce phototoxicity with respect to cellular DNA. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Localized excitations and the geometry of the 1nπ* excited states of pyrazine

International Nuclear Information System (INIS)

Kleier, D.A.; Martin, R.L.; Wadt, W.R.; Moomaw, W.R.

1982-01-01

Previous theoretical work has shown that the lowest excited singlet state of pyrazine, the π* 1 B 3 u state, is best described in terms of interacting excitations localized on each nitrogen. The present work refines the localized excitation model and considers its implications for the geometry of the 1 B 3 u state. Hartree-Fock calculations show that the best single configuration description of the nπ* state has broken ( 1 B 1 ) symmetry with the excitation strongly localized at one end of the molcule. If the symmetry-restricted hf result is used for reference, this localization describes an important correlation effect. The excited-state geometry was probed using configuration interaction wave functions based on the symmetry-restricted orbitals, as well as properly symmetrized ''valance-bond'' wave functions based on the broken symmetry solutions. Both descriptions lead to a very flat potential for a b/sub 1u/ vibrational mode. This mode reduces the molecular geometry from D/sub 2h/ to C/sub 2v/. We present spectroscopic evidence of our own and of other workers which is consistent with such a flat potential

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

Quinary excitation method for pulse compression ultrasound measurements.

Science.gov (United States)

Cowell, D M J; Freear, S

2008-04-01

A novel switched excitation method for linear frequency modulated excitation of ultrasonic transducers in pulse compression systems is presented that is simple to realise, yet provides reduced signal sidelobes at the output of the matched filter compared to bipolar pseudo-chirp excitation. Pulse compression signal sidelobes are reduced through the use of simple amplitude tapering at the beginning and end of the excitation duration. Amplitude tapering using switched excitation is realised through the use of intermediate voltage switching levels, half that of the main excitation voltages. In total five excitation voltages are used creating a quinary excitation system. The absence of analogue signal generation and power amplifiers renders the excitation method attractive for applications with requirements such as a high channel count or low cost per channel. A systematic study of switched linear frequency modulated excitation methods with simulated and laboratory based experimental verification is presented for 2.25 MHz non-destructive testing immersion transducers. The signal to sidelobe noise level of compressed waveforms generated using quinary and bipolar pseudo-chirp excitation are investigated for transmission through a 0.5m water and kaolin slurry channel. Quinary linear frequency modulated excitation consistently reduces signal sidelobe power compared to bipolar excitation methods. Experimental results for transmission between two 2.25 MHz transducers separated by a 0.5m channel of water and 5% kaolin suspension shows improvements in signal to sidelobe noise power in the order of 7-8 dB. The reported quinary switched method for linear frequency modulated excitation provides improved performance compared to pseudo-chirp excitation without the need for high performance excitation amplifiers.

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.

Energy transfer properties and mechanisms

International Nuclear Information System (INIS)

1991-01-01

This report discusses the energy transfer mechanisms in azulene, benzene, toluene, and isotopomers. Also discussed is the coupled energy reservoirs model, quantum effects in energy transfer, NO 2 energy transfer, densities of states, the reactant states model, and O 3 excited electronic states

Block 3 X-band receiver-exciter

Science.gov (United States)

Johns, C. E.

1987-01-01

The development of an X-band exciter, for use in the X-Band Uplink Subsystem, was completed. The exciter generates the drive signal for the X-band transmitter and also generates coherent test signals for the S- and X-band Block 3 translator and a Doppler reference signal for the Doppler extractor system. In addition to the above, the exciter generates other reference signals that are described. Also presented is an overview of the exciter design and some test data taken on the prototype. A brief discussion of the Block 3 Doppler extractor is presented.

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.

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.)

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...

Effects of theta burst stimulation on motor cortex excitability in Parkinson's disease.

Science.gov (United States)

Zamir, Orit; Gunraj, Carolyn; Ni, Zhen; Mazzella, Filomena; Chen, Robert

2012-04-01

Long-term potentiation (LTP)-like plasticity induced by paired associative stimulation (PAS) is impaired in Parkinson's disease (PD). Intermittent theta burst stimulation (iTBS) is another rTMS protocol that produces LTP-like effects and increases cortical excitability but its effects are independent of afferent input. The aim of the present study was to examine the effects of iTBS on cortical excitability in PD. iTBS was applied to the motor cortex in 10 healthy subjects and 12 PD patients ON and OFF dopaminergic medications. Motor evoked potential (MEP) before and for 60 min after iTBS were used to examine the changes in cortical excitability induced by iTBS. Paired-pulse TMS was used to test whether intracortical circuits, including short interval intracortical inhibition, intracortical facilitation, short and long latency afferent inhibition, were modulated by iTBS. After iTBS, the control, PD ON and OFF groups had similar increases in MEP amplitude compared to baseline over the course of 60 min. Changes in intracortical circuits induced by iTBS were also similar for the different groups. iTBS produced similar effects on cortical excitability for PD patients and controls. Spike-timing dependent heterosynaptic LTP-like plasticity induced by PAS may be more impaired in PD than frequency dependent homosynaptic LTP-like plasticity induced by iTBS. Copyright © 2011 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

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...

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

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....

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...

Frenkel and Charge-Transfer Excitations in Donor-acceptor Complexes from Many-Body Green's Functions Theory.

Science.gov (United States)

Baumeier, Björn; Andrienko, Denis; Rohlfing, Michael

2012-08-14

Excited states of donor-acceptor dimers are studied using many-body Green's functions theory within the GW approximation and the Bethe-Salpeter equation. For a series of prototypical small-molecule based pairs, this method predicts energies of local Frenkel and intermolecular charge-transfer excitations with the accuracy of tens of meV. Application to larger systems is possible and allowed us to analyze energy levels and binding energies of excitons in representative dimers of dicyanovinyl-substituted quarterthiophene and fullerene, a donor-acceptor pair used in state of the art organic solar cells. In these dimers, the transition from Frenkel to charge transfer excitons is endothermic and the binding energy of charge transfer excitons is still of the order of 1.5-2 eV. Hence, even such an accurate dimer-based description does not yield internal energetics favorable for the generation of free charges either by thermal energy or an external electric field. These results confirm that, for qualitative predictions of solar cell functionality, accounting for the explicit molecular environment is as important as the accurate knowledge of internal dimer energies.

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

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)

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.

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.

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)

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.

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

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....

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

Fatigue crack detection on structural steel members by using ultrasound excited thermography

Energy Technology Data Exchange (ETDEWEB)

Plum, Robin Marc

2015-07-01

In the field of non-destructive testing (NDT), ultrasound excited thermography has been recognised as a promising technique that was successfully applied to metals, fibre composites and many more engineering materials in order to detect cracks, delaminations and other types of internal flaws. Dating back to the late 1970s, the idea of high-frequency vibration excitation of structural members combined with monitoring the surface temperature by means of infrared thermography aims at the localised energy dissipation at defect regions and its thermal detection. The purpose of this thesis is to investigate the potential use of ultrasound excited thermography for detecting surface breaking fatigue cracks in thick-walled components relevant to steel construction. The presented research is motivated by a lack of fast and imaging crack detection methods in the field and the growing acceptance and technological progress of active thermography techniques. After introducing the concept of ultrasound excited thermography or vibrothermography, its current state of the art is described by means of a comprehensive literature review focusing on research activities towards crack detection on metals. Owing to the interdisciplinarity of the test method, all relevant technical subdisciplines from the excitation of plate vibrations via potential heat generation mechanisms and heat transfer to infrared thermography are outlined. The experimental work starts with the manufacture and fatigue loading of suitable plate specimens made from low-carbon steel S355, mostly in the high cycle fatigue regime, to generate throughthickness cracks with specified depths. Using a modified high-power ultrasonic welding generator, basic dependencies of the defect heating on frequency, coupling location and excitation duration are clarified at first. Besides of an estimation of realistic detection limits depending on the plate thickness, main issues such as the relation between vibration intensity and

Fatigue crack detection on structural steel members by using ultrasound excited thermography

International Nuclear Information System (INIS)

Plum, Robin Marc

2015-01-01

In the field of non-destructive testing (NDT), ultrasound excited thermography has been recognised as a promising technique that was successfully applied to metals, fibre composites and many more engineering materials in order to detect cracks, delaminations and other types of internal flaws. Dating back to the late 1970s, the idea of high-frequency vibration excitation of structural members combined with monitoring the surface temperature by means of infrared thermography aims at the localised energy dissipation at defect regions and its thermal detection. The purpose of this thesis is to investigate the potential use of ultrasound excited thermography for detecting surface breaking fatigue cracks in thick-walled components relevant to steel construction. The presented research is motivated by a lack of fast and imaging crack detection methods in the field and the growing acceptance and technological progress of active thermography techniques. After introducing the concept of ultrasound excited thermography or vibrothermography, its current state of the art is described by means of a comprehensive literature review focusing on research activities towards crack detection on metals. Owing to the interdisciplinarity of the test method, all relevant technical subdisciplines from the excitation of plate vibrations via potential heat generation mechanisms and heat transfer to infrared thermography are outlined. The experimental work starts with the manufacture and fatigue loading of suitable plate specimens made from low-carbon steel S355, mostly in the high cycle fatigue regime, to generate throughthickness cracks with specified depths. Using a modified high-power ultrasonic welding generator, basic dependencies of the defect heating on frequency, coupling location and excitation duration are clarified at first. Besides of an estimation of realistic detection limits depending on the plate thickness, main issues such as the relation between vibration intensity and

Electron impact excitation of xenon from the metastable state to the excited states

Energy Technology Data Exchange (ETDEWEB)

Jiang Jun; Dong Chenzhong; Xie Luyou; Zhou Xiaoxin [College of Physics and Electronic Engineering, Northwest Normal University, Lanzhou 730070 (China); Wang Jianguo [Institute of Applied Physics and Computational Mathematic, Beijing 100088 (China)], E-mail: dongcz@nwnu.edu.cn

2008-12-28

The electron impact excitation cross sections from the lowest metastable state 5p{sup 5}6sJ = 2 to the six lowest excited states of the 5p{sup 5}6p configuration of xenon are calculated systematically by using the fully relativistic distorted wave method. In order to discuss the effects of target state descriptions on the electron impact excitation cross sections, two correlation models are used to describe the target states based on the multiconfiguration Dirac-Fock (MCDF) method. It is found that the correlation effects play a very important role in low energy impact. For high energy impact, however, the cross sections are not sensitive to the description of the target states, but many more partial waves must be included.

Contextualising the Individual in International Management Research

DEFF Research Database (Denmark)

Minbaeva, Dana

2016-01-01

In this paper, I call for further contextualisation of the individual in international management research. In this 'opinion piece', my goal is to stimulate debate and elicit a thoughtful reaction. Accordingly, this paper aims to provoke and excite, rather than review and summarise. On the basis ...

Contextualising the Individual in International Management Research

DEFF Research Database (Denmark)

Minbaeva, Dana

2016-01-01

In this paper, I call for further contextualisation of the individual in international management research. In this 'opinion piece', my goal is to stimulate debate and elicit a thoughtful reaction. Accordingly, this paper aims to provoke and excite, rather than review and summarise. On the basis...

Excited-state Raman spectroscopy with and without actinic excitation: S1 Raman spectra of trans-azobenzene

International Nuclear Information System (INIS)

Dobryakov, A. L.; Quick, M.; Ioffe, I. N.; Granovsky, A. A.; Ernsting, N. P.; Kovalenko, S. A.

2014-01-01

We show that femtosecond stimulated Raman spectroscopy can record excited-state spectra in the absence of actinic excitation, if the Raman pump is in resonance with an electronic transition. The approach is illustrated by recording S 1 and S 0 spectra of trans-azobenzene in n-hexane. The S 1 spectra were also measured conventionally, upon nπ* (S 0 → S 1 ) actinic excitation. The results are discussed and compared to earlier reports

Proving test on the performance of a Multiple-Excitation Simulator

International Nuclear Information System (INIS)

Fujita, Katsuhisa; Ito, Tomohiro; Kojima, Nobuyuki; Sasaki, Yoichi; Abe, Hiroshi; Kuroda, Katsuhiko

1995-01-01

Seismic excitation test on large scale piping systems is scheduled to be carried out by the Nuclear power Engineering Corporation (NUPEC) using the large-scale, high-performance vibration table at the Tadotsu Engineering Laboratory, under the sponsorship of the Ministry of International Trade and Industry (MITI). In the test, the piping systems simulate the main steam piping system and the main feed water piping system in the nuclear power plants. In this study, a fundamental test was carried out to prove the performance of the Multiple Excitation Simulator which consists of the hydraulic actuator and the control system. An L-shaped piping system and a hydraulic actuator were installed on the shaking table. Acceleration and displacement generated by the actuator were measured. The performance of the actuator and the control system was discussed comparing the measured values and the target values on the time histories and the response spectrum of the acceleration. As a result, it was proved that the actuator and the control system have good performance and will be applicable to the verification test

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.

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.

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....

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)

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.

Structures excited by heavy ions in 208Pb target. Interpretation involving giant resonances and multiphonon excitations

International Nuclear Information System (INIS)

Chomaz, P.

1984-01-01

Kinetic energy spectra of heavy fragments from the 36Ar+208Pb reaction at 11 MeV/n and 20 Ne+ 208 Pb at 30 MeV/n have been measured with a time of flight spectrometer. Numerous structures ranging up to 100 MeV excitation energy are observed in the inelastic and few nucleon transfer channels. These structures are shown to be due to an excitation of the 208 Pb target nucleus and not to decay products of excited ejectiles. Positions of low lying structures (E* 208 Pb. The linear response of the target nucleus to the external field created by the projectile is calculated microscopically in the Random Phase Approximation resolved using the Green's function method in coordinate space with a Skyrme interaction. In the independant quasi-boson approximation multiple phonon excitations reproduce the main features of the experimental data and appear as a plausible interpretation of the observed structures. The theoretical calculations and experimental observations suggest that multiphonon excitations play an important role in heavy ion reactions and contribute strongly to the kinetic energy dissipation [fr

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.)

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

Electron-impact excitation and ionization cross sections for ground state and excited helium atoms

International Nuclear Information System (INIS)

Ralchenko, Yu.; Janev, R.K.; Kato, T.; Fursa, D.V.; Bray, I.; Heer, F.J. de

2008-01-01

Comprehensive and critically assessed cross sections for the electron-impact excitation and ionization of ground state and excited helium atoms are presented. All states (atomic terms) with n≤4 are treated individually, while the states with n≥5 are considered degenerate. For the processes involving transitions to and from n≥5 levels, suitable cross section scaling relations are presented. For a large number of transitions, from both ground and excited states, convergent close coupling calculations were performed to achieve a high accuracy of the data. The evaluated/recommended cross section data are presented by analytic fit functions, which preserve the correct asymptotic behavior of the cross sections. The cross sections are also displayed in graphical form

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

A new autogenous mobile system driven by vibration without impacts, excited by an impulse periodic force

Directory of Open Access Journals (Sweden)

Duong The-Hung

2018-01-01

Full Text Available This report describes a new proposed design for autogenous mobile systems which can move without any external mechanisms such as legs or wheels. A Duffing oscillator with a cubic spring, which is excited by an impulse periodic force, is utilized to drive the whole system. The rectilinear motion of the system is performed employing the periodically oscillation of the internal mass interacting without collisions with the main body. Utilizing the nonlinear restoring force of the cubic spring, the system can move in desired directions. When the ratio between the excitation force and the friction force is smaller than 2.5, backward or forward motion can be easily achieved by applying an excitation force in the same desired direction. Different from other vibro-impact drifting devices, no impact needed to drive the new proposed system. This novel structure allows to miniaturize the device as well as to simplify the control algorithm thus can significantly expand applicability of the proposed system.

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

Excited states configurations of the quantum Toda lattice

International Nuclear Information System (INIS)

Matsuyama, A.

2001-01-01

Excited states configurations of the quantum Toda lattice are studied by the direct diagonalization of the Hamiltonian. The most probable configurations of one-hole and one-particle excitations are shown to be similar to the profiles of classical phonon and soliton excitations, respectively. One-hole excitation states, which are always ground states of definite E m -symmetry of the dihedral group D N , change those structures abruptly with the potential range varied. One-particle excitations, which are buried in complicated excitation spectra, have well-defined configurations similar to the conoidal profile of the classical periodic Toda lattice. The relationship that the hole (particle) excitations in quantum mechanics correspond to the phonon (soliton) excitations in classical mechanics, which has been suggested based on the similarity of dispersion relations, is confirmed in a geometrically understandable way. Based on the study of one-soliton and two-soliton states, the structure of multi-soliton states in quantum mechanics can be conjectured

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.

Energy transfer in diatom/diatom molecular collisions

International Nuclear Information System (INIS)

Sohlberg, K.W.

1992-01-01

In a collision of two molecules, the translational energy of the collision may be redistributed into internal energy of rotation, vibration, or electron motion, in one or both of the colliding partners. In addition, internal energy in one or more of these modes may be open-quotes quenchedclose quotes into translation, leading to a superelastic collision. Such energy transfer may take place by a number of mechanisms. This energy transfer is of fundamental importance in understanding chemical reaction dynamics. Nearly all chemical reactions take place through a bimolecular collision process (or multiple bimolecular collisions) and the quantum state specificity of the reaction can have a major role in determining the kinetics of the reaction, In particular, the author has investigated vibrational energy transfer in collisions between two diatomic molecules. In addition to serving as models for all molecular collision process, gas phase collisions of these species are ubiquitous in atmospheric phenomena which are of critical importance in answering the current questions about the human induced degradation of the earth's atmospheric. Classical trajectory methods have been used to explore the excitation of vibrations in gas-phase collisions of the nitrogen molecular ion with its parent molecule. The near symmetry of the reactants is shown to result in a high probability that the two molecules are excited by an equal amount of energy. This provides a possible explanation of the molecular beam measurements which show that the total number of vibrational energy quanta excited in the collision is, with a high probability that the two molecules are excited by an equal amount of energy. This provides a possible explanation of the molecular beam measurements which show that the total number of vibrational energy quanta excited in the collision is, with a high probability, even

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

Excitation dynamics and relaxation in a molecular heterodimer

International Nuclear Information System (INIS)

Balevičius, V.; Gelzinis, A.; Abramavicius, D.; Mančal, T.; Valkunas, L.

2012-01-01

Highlights: ► Dynamics of excitation within a heterogenous molecular dimer. ► Excited states can be swapped due to different reorganization energies of monomers. ► Conventional excitonic basis becomes renormalized due to interaction with the bath. ► Relaxation is independent of mutual positioning of monomeric excited states. -- Abstract: The exciton dynamics in a molecular heterodimer is studied as a function of differences in excitation and reorganization energies, asymmetry in transition dipole moments and excited state lifetimes. The heterodimer is composed of two molecules modeled as two-level systems coupled by the resonance interaction. The system-bath coupling is taken into account as a modulating factor of the molecular excitation energy gap, while the relaxation to the ground state is treated phenomenologically. Comparison of the description of the excitation dynamics modeled using either the Redfield equations (secular and full forms) or the Hierarchical quantum master equation (HQME) is demonstrated and discussed. Possible role of the dimer as an excitation quenching center in photosynthesis self-regulation is discussed. It is concluded that the system-bath interaction rather than the excitonic effect determines the excitation quenching ability of such a dimer.

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....

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

Self-excited vibration control for axially fast excited beam by a time delay state feedback

International Nuclear Information System (INIS)

Hamdi, Mustapha; Belhaq, Mohamed

2009-01-01

This work examines the control of self-excited vibration of a simply-supported beam subjected to an axially high-frequency excitation. The investigation of the resonant cases are not considered in this paper. The control is implemented via a corrective position feedback with time delay. The objective of this control is to eliminate the undesirable self-excited vibrations with an appropriate choice of parameters. The issue of stability is also addressed in this paper. Using the technique of direct partition of motion, the dynamic of discretized equations is separated into slow and fast components. The multiple scales method is then performed on the slow dynamic to obtain a slow flow for the amplitude and phase. Analysis of this slow flow provides analytical approximations locating regions in parameters space where undesirable self-excited vibration can be eliminated. A numerical study of these regions is performed on the original discretized system and compared to the analytical prediction showing a good agreement.

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

Site selective dissociation of ozone upon core excitation

International Nuclear Information System (INIS)

Mocellin, A.; Mundim, M.S.P.; Coutinho, L.H.; Homem, M.G.P.; Naves de Brito, A.

2007-01-01

We present new measurements applied to core excitation of ozone molecule using to analyze the dissociation channels the photo-electron-photo-ion coincidence (PEPICO) and the photo-electron-photo-ion-photo-ion coincidence (PEPIPICO) technique. The new experimental set-up allows measuring O + /O + ion pair coincidences without discrimination. The dissociation channels of several core-excited states have been investigated. The relative yields of dissociation channels were determined from coincidence data. The core excitation from O terminal (O T ) or O central (O C ) induce different fragmentation; preferentially one bond is broken at the O terminal excitation and two bonds when O central is excited, showing site selectivity fragmentation of ozone upon core excitation. The ultra-fast dissociation of the O T 1s -1 7a 1 1 core-excited state is confirmed by the relative yield of dissociation

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.

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.)

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.

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....

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....

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.)

On Rhythms in Neuronal Networks with Recurrent Excitation.

Science.gov (United States)

Börgers, Christoph; Takeuchi, R Melody; Rosebrock, Daniel T

2018-02-01

We investigate rhythms in networks of neurons with recurrent excitation, that is, with excitatory cells exciting each other. Recurrent excitation can sustain activity even when the cells in the network are driven below threshold, too weak to fire on their own. This sort of "reverberating" activity is often thought to be the basis of working memory. Recurrent excitation can also lead to "runaway" transitions, sudden transitions to high-frequency firing; this may be related to epileptic seizures. Not all fundamental questions about these phenomena have been answered with clarity in the literature. We focus on three questions here: (1) How much recurrent excitation is needed to sustain reverberating activity? How does the answer depend on parameters? (2) Is there a positive minimum frequency of reverberating activity, a positive "onset frequency"? How does it depend on parameters? (3) When do runaway transitions occur? For reduced models, we give mathematical answers to these questions. We also examine computationally to which extent our findings are reflected in the behavior of biophysically more realistic model networks. Our main results can be summarized as follows. (1) Reverberating activity can be fueled by extremely weak slow recurrent excitation, but only by sufficiently strong fast recurrent excitation. (2) The onset of reverberating activity, as recurrent excitation is strengthened or external drive is raised, occurs at a positive frequency. It is faster when the external drive is weaker (and the recurrent excitation stronger). It is slower when the recurrent excitation has a longer decay time constant. (3) Runaway transitions occur only with fast, not with slow, recurrent excitation. We also demonstrate that the relation between reverberating activity fueled by recurrent excitation and runaway transitions can be visualized in an instructive way by a (generalized) cusp catastrophe surface.

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).

Comparison of sensitivities and detection limits between direct excitation and secondary excitation modes in energy dispersive x-ray fluorescence analysis

International Nuclear Information System (INIS)

Artz, B.E.; Short, M.A.

1976-01-01

A comparison was made between the direct tube excitation mode and the secondary target excitation mode using a Kevex 0810 energy dispersive x-ray fluorescence system. Relative sensitivities and detection limits were determined with two system configurations. The first configuration used a standard, high power, x-ray fluorescence tube to directly excite the specimen. Several x-ray tubes, including chromium, molybdenum, and tungsten, both filtered and not filtered, were employed. The second configuration consisted of using the x-ray tube to excite a secondary target which in turn excited the specimen. Appropriate targets were compared to the direct excitation results. Relative sensitivities and detection limits were determined for K-series lines for elements from magnesium to barium contained in a low atomic number matrix and in a high atomic number matrix

Influence of different environments on the excited-state proton transfer and dual fluorescence of fisetin

Science.gov (United States)

Guharay, Jayanti; Dennison, S. Moses; Sengupta, Pradeep K.

1999-05-01

The influence of different protic and aprotic solvent environments on the excited-state intramolecular proton transfer (ESIPT) leading to a dual fluorescence behaviour of a biologically important, naturally occurring, polyhydroxyflavone, fisetin (3,3',4',7-tetrahydroxyflavone), has been investigated. The normal fluorescence band, in particular, is extremely sensitive to solvent polarity with νmax shifting from 24 510 cm -1 in dioxane ( ET(30)=36.0) to 20 790 cm -1 in methanol ( ET(30)=55.5). This is rationalized in terms of solvent dipolar relaxation process, which also accounts for the red edge excitation shifts (REES) observed in viscous environments such as glycerol at low temperatures. Significant solvent dependence of the tautomer fluorescence properties ( νmax, yield and decay kinetics) reveals the influence of external hydrogen bonding perturbation on the internal hydrogen bond of the molecule. These excited-state relaxation phenomena and their relevant parameters have been used to probe the microenvironment of fisetin in a membrane mimetic system, namely AOT reverse micelles in n-heptane at different water/surfactant molar ratio ( w0).

Localizations in cellular automata with mutualistic excitation rules

International Nuclear Information System (INIS)

Adamatzky, Andrew

2009-01-01

Every cell of two-dimensional cellular automaton with eight-cell neighborhood takes three states: resting, excited and refractory, and updates excited to refractory and refractory to resting states unconditionally. A resting cell excites depending on number of excited and refractory neighbors. We made exhaustive study of spatio-temporal excitation dynamics for all rules of this type and selected several classes of rules. The classes supporting self-localizations are studied in details. We uncover basic types of mobile (gliders) and stationary localizations, and characterize their morphology and dynamics.

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.

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)

Site selective dissociation of ozone upon core excitation

Energy Technology Data Exchange (ETDEWEB)

Mocellin, A. [Instituto de Fisica, Universidade de Brasilia-UnB, Box 04455, CEP 70919-970, Brasilia-DF (Brazil)], E-mail: mocellin@fis.unb.br; Mundim, M.S.P. [Instituto de Fisica, Universidade de Brasilia-UnB, Box 04455, CEP 70919-970, Brasilia-DF (Brazil); Coutinho, L.H. [Instituto de Quimica, Universidade Federal do Rio de Janeiro-UFRJ, Box 68563, CEP 21945-970, Rio de Janeiro-RJ (Brazil); Homem, M.G.P. [Laboratorio Nacional de Luz Sincrotron-LNLS, Box 6192, CEP 13084-971, Campinas-SP (Brazil); Naves de Brito, A. [Laboratorio Nacional de Luz Sincrotron-LNLS, Box 6192, CEP 13084-971, Campinas-SP (Brazil); Instituto de Fisica, Universidade de Brasilia-UnB, Box 04455, CEP 70919-970, Brasilia-DF (Brazil)

2007-05-15

We present new measurements applied to core excitation of ozone molecule using to analyze the dissociation channels the photo-electron-photo-ion coincidence (PEPICO) and the photo-electron-photo-ion-photo-ion coincidence (PEPIPICO) technique. The new experimental set-up allows measuring O{sup +}/O{sup +} ion pair coincidences without discrimination. The dissociation channels of several core-excited states have been investigated. The relative yields of dissociation channels were determined from coincidence data. The core excitation from O terminal (O{sub T}) or O central (O{sub C}) induce different fragmentation; preferentially one bond is broken at the O terminal excitation and two bonds when O central is excited, showing site selectivity fragmentation of ozone upon core excitation. The ultra-fast dissociation of the O{sub T} 1s{sup -1}7a{sub 1}{sup 1} core-excited state is confirmed by the relative yield of dissociation.

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

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.

Coherence in electron-impact excitation of helium

International Nuclear Information System (INIS)

Batelaan, Hermanus.

1991-01-01

This thesis describes an experimental study into the electron-impact excitation to the 3 3 P, 3 1 D and 3 3 D states of Helium. The scattered electron and the photon, emitted by the excited atom, are measured in coincidence. The parameters, which can be varied, are the scattering angle and the kinetic energy of the projectile. Two parameters, which are used to characterize the excited state, are the angular momentum transferred to the atom, L perpendicular, and the alignment angle γ. It is shown that results of measurements on 3 1 D excitation with photon detection perpendicular to the scattering plane do not agree in the small scattering angle region with any of the model calculations currently available. Remarkable is the sign of L perpendicular, which appears to start of negatively at 60 eV. It is shown that for 3 3 P excitation the predicted large value of γ is indeed found experimentally. This supports the suggestion that exchange scattering is underestimated in model calculations for 1 P excitation. Another result is that for 1 P and 3 P excitation the behaviour of L perpendicular as a function of the scattering angle can be related at different impact energies with the help of a partial wave expansion. A scaling relation can be formulated for the behaviour of L perpendicular. The influence of a negative ion resonance to excitation of the 3 3 D state is investigated. Both in coincidence and non-coincidence measurements the presence of the resonance yields information on both the direct and indirect excitation of the 3 3 D state. It is shown that the coincident measurement gives an unique opportunity to determine the excited 3 3 D state completely. Results of measurements with photon detection in the scattering plane are given. They supplement previous 3 1 D and 3 3 D results and allow physical parameters, such as L perpendicular and γ, to be obtained. (H.W.). 132 refs.; 20 figs.; 18 tabs

Excited-state Raman spectroscopy with and without actinic excitation: S{sub 1} Raman spectra of trans-azobenzene

Energy Technology Data Exchange (ETDEWEB)

Dobryakov, A. L.; Quick, M.; Ioffe, I. N.; Granovsky, A. A.; Ernsting, N. P.; Kovalenko, S. A. [Department of Chemistry, Humboldt-Universität zu Berlin, Brook-Taylor-Str. 2, D-12489 Berlin (Germany)

2014-05-14

We show that femtosecond stimulated Raman spectroscopy can record excited-state spectra in the absence of actinic excitation, if the Raman pump is in resonance with an electronic transition. The approach is illustrated by recording S{sub 1} and S{sub 0} spectra of trans-azobenzene in n-hexane. The S{sub 1} spectra were also measured conventionally, upon nπ* (S{sub 0} → S{sub 1}) actinic excitation. The results are discussed and compared to earlier reports.

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

UV excitation of single DNA and RNA strands produces high yields of exciplex states between two stacked bases.

Science.gov (United States)

Takaya, Tomohisa; Su, Charlene; de La Harpe, Kimberly; Crespo-Hernández, Carlos E; Kohler, Bern

2008-07-29

Excited electronic states created by UV excitation of the diribonucleoside monophosphates ApA, ApG, ApC, ApU, and CpG were studied by the femtosecond transient-absorption technique. Bleach recovery signals recorded at 252 nm show that long-lived excited states are formed in all five dinucleosides. The lifetimes of these states exceed those measured in equimolar mixtures of the constituent mononucleotides by one to two orders of magnitude, indicating that electronic coupling between proximal nucleobases dramatically slows the relaxation of excess electronic energy. The decay rates of the long-lived states decrease with increasing energy of the charge-transfer state produced by transferring an electron from one base to another. The charge-transfer character of the long-lived states revealed by this analysis supports their assignment to excimer or exciplex states. Identical bleach recovery signals were seen for ApA, (A)(4), and poly(A) at delay times >10 ps after photoexcitation. This indicates that excited states localized on a stack of just two bases are the common trap states independent of the number of stacked nucleotides. The fraction of initial excitations that decay to long-lived exciplex states is approximately equal to the fraction of stacked bases determined by NMR measurements. This supports a model in which excitations associated with two stacked bases decay to exciplex states, whereas excitations in unstacked bases decay via ultrafast internal conversion. These results establish the importance of charge transfer-quenching pathways for UV-irradiated RNA and DNA in room-temperature solution.

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)

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

Long-range electron transfer in porphyrin-containing [2]-rotaxanes: tuning the rate by metal cation coordination.

Science.gov (United States)

Andersson, Mikael; Linke, Myriam; Chambron, Jean-Claude; Davidsson, Jan; Heitz, Valérie; Hammarström, Leif; Sauvage, Jean-Pierre

2002-04-24

A series of [2]-rotaxanes has been synthesized in which two Zn(II)-porphyrins (ZnP) electron donors were attached as stoppers on the rod. A macrocycle attached to a Au(III)-porphyrin (AuP+) acceptor was threaded on the rod. By selective excitation of either porphyrin, we could induce an electron transfer from the ZnP to the AuP+ unit that generated the same ZnP*+-AuP* charge-transfer state irrespective of which porphyrin was excited. Although the reactants were linked only by mechanical or coordination bonds, electron-transfer rate constants up to 1.2x10(10) x s(-1) were obtained over a 15-17 A edge-to-edge distance between the porphyrins. The resulting charge-transfer state had a relatively long lifetime of 10-40 ns and was formed in high yield (>80%) in most cases. By a simple variation of the link between the reactants, viz. a coordination of the phenanthroline units on the rotaxane rod and ring by either Ag+ or Cu+, we could enhance the electron-transfer rate from the ZnP to the excited 3AuP+. We interpret our data in terms of an enhanced superexchange mechanism with Ag+ and a change to a stepwise hopping mechanism with Cu+, involving the oxidized Cu(phen)22+ unit as a real intermediate. When the ZnP unit was excited instead, electron transfer from the excited 1ZnP to AuP+ was not affected, or even slowed, by Ag+ or Cu+. We discuss this asymmetry in terms of the different orbitals involved in mediating the reaction in an electron- and a hole-transfer mechanism. Our results show the possibility to tune the rates of electron transfer between noncovalently linked reactants by a convenient modification of the link. The different effect of Ag+ and Cu+ on the rate with ZnP and AuP+ excitation shows an additional possibility to control the electron-transfer reactions by selective excitation. We also found that coordination of the Cu+ introduced an energy-transfer reaction from 1ZnP to Cu(phen)2+ (k = 5.1x10(9) x s(-1)) that proceeded in competition with electron

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.

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.

Nested variant of the method of moments of coupled cluster equations for vertical excitation energies and excited-state potential energy surfaces.

Science.gov (United States)

Kowalski, Karol

2009-05-21

In this article we discuss the problem of proper balancing of the noniterative corrections to the ground- and excited-state energies obtained with approximate coupled cluster (CC) and equation-of-motion CC (EOMCC) approaches. It is demonstrated that for a class of excited states dominated by single excitations and for states with medium doubly excited component, the newly introduced nested variant of the method of moments of CC equations provides mathematically rigorous way of balancing the ground- and excited-state correlation effects. The resulting noniterative methodology accounting for the effect of triples is tested using its parallel implementation on the systems, for which iterative CC/EOMCC calculations with full inclusion of triply excited configurations or their most important subset are numerically feasible.

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.

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

Process to produce excited states of atomic nuclei

International Nuclear Information System (INIS)

Morita, M.; Morita, R.

The claims of a patented process which relates to the production of excited states of atomic nuclei are outlined. Among these are (1) production of nuclear excited states by bombarding the atoms with x rays or electrons under given conditions, (2) production of radioactive substances by nuclear excitation with x rays or electrons, (3) separation of specific isotopes from a mixture of isotopes of the same element by means of nuclear excitation followed by chemical treatment. The invention allows production of excited states of atomic nuclei in a relatively simple manner without the need of large apparatus and equipment

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.)

New features of nuclear excitation by {alpha} particles scattering; Nouveaux aspects de l'excitation nucleaire par diffusion de particules {alpha}

Energy Technology Data Exchange (ETDEWEB)

Saudinos, J [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1962-07-01

Inelastic scattering of medium energy a particles by nuclei is known to excite preferentially levels of collective character. We have studied the scattering of isotopically enriched targets of Ca, Fe, Ni, Cu, Zn. In part I, we discuss the theoretical features of the interaction. In part II, we describe the experimental procedure. Results are presented and analysed in part III. {alpha} particles scattering by Ca{sup 40} is showed to excite preferentially odd parity levels. In odd nuclei we have observed multiplets due to the coupling of the odd nucleon with the even-even core vibrations. For even-even nuclei, a few levels are excited with lower cross-sections between the well-known first 2{sup +} and 3{sup -} states. Some could be members of the two phonon quadrupole excitation and involve a double nuclear excitation process. (author) [French] On sait que la diffusion inelastique des particules alpha de moyenne energie excite preferentiellement des niveaux de caractere collectif. Nous avons etudie la diffusion des particules alpha de 44 MeV du cyclotron de Saclay par des isotopes separes de Ca, Fe, Ni, Cu, Zn. Dans la premiere partie nous exposons les theories de cette interaction. Dans la seconde nous decrivons le systeme experimental. Les resultats sont donnes dans la troisieme partie. Nous montrons que les niveaux excites preferentiellement pour {sup 40}Ca par diffusion ({alpha},{alpha}') sont de parite negative. Dans les noyaux pair-impair nous avons observe des multiplets dus au couplage du nucleon celibataire avec les vibrations du coeur pair-pair. Pour les noyaux pair-pair nous avons pu etudier entre le premier niveau 2{sup +} et le niveau 3{sup -} deja bien connus certains etats plus faiblement excites. Il semble qu'ils sont dus a une excitation quadrupolaire a deux phonons et impliquent un processus de double excitation nucleaire. (auteur)

Canard and mixed mode oscillations in an excitable glow discharge plasma in the presence of inhomogeneous magnetic field

Energy Technology Data Exchange (ETDEWEB)

Shaw, Pankaj Kumar, E-mail: pankaj.shaw@saha.ac.in; Sekar Iyengar, A. N., E-mail: ansekar.iyengar@saha.ac.in [Plasma Physics Division, Saha Institute of Nuclear Physics, 1/AF, Bidhannagar, Kolkata 700064 (India); Nurujjaman, Md., E-mail: jaman-nonlinear@yahoo.co.in [Department of Physics, National Institute of Technology Sikkim, Ravangla, Sikkim 737139 (India)

2015-12-15

We report on the experimental observation of canard orbit and mixed mode oscillations (MMOs) in an excitable glow discharge plasma induced by an external magnetic field perturbation using a bar magnet. At a small value of magnetic field, small amplitude quasiperiodic oscillations were excited, and with the increase in the magnetic field, large amplitude oscillations were excited. Analyzing the experimental results, it seems that the magnetic field could be playing the role of noise for such nonlinear phenomena. It is observed that the noise level increases with the increase in magnetic field strength. The experimental results have also been corroborated by a numerical simulation using a FitzHugh-Nagumo like macroscopic model derived from the basic plasma equations and phenomenology, where the noise has been included to represent the internal plasma noise. This macroscopic model shows MMO in the vicinity of the canard point when an external noise is added.

Reflections on Dead Theory in International Relations

Science.gov (United States)

Thakur, Vineet

2016-01-01

In this short autobiographical essay, I trace my journey in the discipline of International Relations. While entering the discipline, I, along with a host of my classmates, were enamoured by the exciting possibilities of thinking theoretically. Almost a decade later, those promises look bleak. From the perspective of a student in the discipline, I…

IUPESM: the international umbrella organisation for biomedical engineering and medical physics

Science.gov (United States)

2007-01-01

An account of the development, aims and activities of the International Union for Physical and Engineering Sciences in Medicine (IUPESM) is presented. Associations with the International Council of Science (ICSU) and the World Health Organization (WHO) are leading to exciting new projects towards improving global health, healthcare, quality of life and support of health technologies in developing countries. PMID:21614293

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.

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.

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...

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...

Excitation power quantities in phase resonance testing of nonlinear systems with phase-locked-loop excitation

Science.gov (United States)

Peter, Simon; Leine, Remco I.

2017-11-01

Phase resonance testing is one method for the experimental extraction of nonlinear normal modes. This paper proposes a novel method for nonlinear phase resonance testing. Firstly, the issue of appropriate excitation is approached on the basis of excitation power considerations. Therefore, power quantities known from nonlinear systems theory in electrical engineering are transferred to nonlinear structural dynamics applications. A new power-based nonlinear mode indicator function is derived, which is generally applicable, reliable and easy to implement in experiments. Secondly, the tuning of the excitation phase is automated by the use of a Phase-Locked-Loop controller. This method provides a very user-friendly and fast way for obtaining the backbone curve. Furthermore, the method allows to exploit specific advantages of phase control such as the robustness for lightly damped systems and the stabilization of unstable branches of the frequency response. The reduced tuning time for the excitation makes the commonly used free-decay measurements for the extraction of backbone curves unnecessary. Instead, steady-state measurements for every point of the curve are obtained. In conjunction with the new mode indicator function, the correlation of every measured point with the associated nonlinear normal mode of the underlying conservative system can be evaluated. Moreover, it is shown that the analysis of the excitation power helps to locate sources of inaccuracies in the force appropriation process. The method is illustrated by a numerical example and its functionality in experiments is demonstrated on a benchmark beam structure.

Structural dynamics of phenylisothiocyanate in the light-absorbing excited states: Resonance Raman and complete active space self-consistent field calculation study

International Nuclear Information System (INIS)

Ouyang, Bing; Xue, Jia-Dan; Zheng, Xuming; Fang, Wei-Hai

2014-01-01

The excited state structural dynamics of phenyl isothiocyanate (PITC) after excitation to the light absorbing S 2 (A′), S 6 (A′), and S 7 (A′) excited states were studied by using the resonance Raman spectroscopy and complete active space self-consistent field method calculations. The UV absorption bands of PITC were assigned. The vibrational assignments were done on the basis of the Fourier transform (FT)-Raman and FT-infrared measurements, the density-functional theory computations, and the normal mode analysis. The A-, B-, and C-bands resonance Raman spectra in cyclohexane, acetonitrile, and methanol solvents were, respectively, obtained at 299.1, 282.4, 266.0, 252.7, 228.7, 217.8, and 208.8 nm excitation wavelengths to probe the corresponding structural dynamics of PITC. The results indicated that the structural dynamics in the S 2 (A′), S 6 (A′), and S 7 (A′) excited states were very different. The conical intersection point CI(S 2 /S 1 ) were predicted to play important role in the low-lying excited state decay dynamics. Two major decay channels were predicted for PITC upon excitation to the S 2 (A′) state: the radiative S 2,min → S 0 transition and the nonradiative S 2 → S 1 internal conversion via CI(S 2 /S 1 ). The differences in the decay dynamics between methyl isothiocyanate and PITC in the first light absorbing excited state were discussed. The role of the intersystem crossing point ISC(S 1 /T 1 ) in the excited state decay dynamics of PITC is evaluated

Powerful highly efficient KrF lamps excited by surface and barrier discharges

International Nuclear Information System (INIS)

Borisov, V M; Vodchits, V A; El'tsov, A V; Khristoforov, O B

1998-01-01

An investigation was made of the characteristics of KrF lamps with different types of excitation by surface and barrier discharges in which the dielectric material was sapphire. The conditions were determined for the attainment of an extremely high yield of the KrF* fluorescence with the internal efficiency η in ∼30 % and 22% for pulsed surface and barrier discharges, respectively. A homogeneous surface discharge was maintained without gas circulation when the pulse repetition rate was 5 x 10 4 Hz. Quasicontinuous excitation of a surface discharge at near-atmospheric pressure made it possible to reach a KrF* fluorescence power density of about 80 W cm -3 , which was close to the limit set by the kinetics of the gaseous medium. Under prolonged excitation conditions the intensity of the UV output radiation was limited by the permissible heating of the gas to a temperature above which the operating life of the gaseous mixture containing fluorine fell steeply. This was the reason for the advantage of surface over barrier discharges: the former were characterised by a high thermal conductivity of a thin (∼0.2 mm) plasma layer on the surface of the cooled dielectric, which made it possible to construct powerful highly efficient KrF and ArF lamps emitting UV radiation of up to 1 W cm -2 intensity. (laser system components)

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.

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.

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

KEWPIE2: A cascade code for the study of dynamical decay of excited nuclei

OpenAIRE

Lu , H.; Marchix , A.; Abe , Y.; Boilley , D.

2016-01-01

Submitted to Computer Physics Communications; International audience; KEWPIE — a cascade code devoted to investigating the dynamical decay of excited nuclei, specially designed for treating very low probability events related to the synthesis of super-heavy nuclei formed in fusion-evaporation reactions — has been improved and rewritten in C++ programing language to become KEWPIE2. The current version of the code comprises various nuclear models concerning the light-particle emission, fission ...

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

Band excitation method applicable to scanning probe microscopy

Science.gov (United States)

Jesse, Stephen [Knoxville, TN; Kalinin, Sergei V [Knoxville, TN

2010-08-17

Methods and apparatus are described for scanning probe microscopy. A method includes generating a band excitation (BE) signal having finite and predefined amplitude and phase spectrum in at least a first predefined frequency band; exciting a probe using the band excitation signal; obtaining data by measuring a response of the probe in at least a second predefined frequency band; and extracting at least one relevant dynamic parameter of the response of the probe in a predefined range including analyzing the obtained data. The BE signal can be synthesized prior to imaging (static band excitation), or adjusted at each pixel or spectroscopy step to accommodate changes in sample properties (adaptive band excitation). An apparatus includes a band excitation signal generator; a probe coupled to the band excitation signal generator; a detector coupled to the probe; and a relevant dynamic parameter extractor component coupled to the detector, the relevant dynamic parameter extractor including a processor that performs a mathematical transform selected from the group consisting of an integral transform and a discrete transform.

Coulomb excitation of atoms by fast multicharged ions

International Nuclear Information System (INIS)

Yudin, G.L.

1980-01-01

Investigated is coulomb eXcitation of discrete levels of a hydrogen-like atom by a fast multicharged ion. Obtained are dependences of probabilities of channels 1S→nS and 1S→nP on the sight parameter in the zero order of sudden excitation theory. 1S-2S transition is considered in detail. Carried out are calculations for excitation of the hydrogen atom by the wholy bare carbon atom. It is shown, that at low values of excitation pr.ocess parameter eta excitation probability is a monotonously decreasing function of the impact parameter. With the growth of eta the situation is changed, and at low impact parameters the probability of 1S-2S transition is decreased. At high impact parameters approximation of sudden excitations is unacceptable, here lagging of coulomb interaction is essential

Electron distribution function in electron-beam-excited plasmas

International Nuclear Information System (INIS)

Brau, C.A.

1976-01-01

In monatomic plasmas excited by high-intensity relativistic electron beams, the electron secondary distribution function is dominated by elastic electron-electron collisions at low electron energies and by inelastic electron-atom collisions at high electron energies (above the excitation threshold). Under these conditions, the total rate of excitation by inelastic collisions is limited by the rate at which electron-electron collisions relax the distribution function in the neighborhood of the excitation threshold. To describe this effect quantitatively, an approximate analytic solution of the electron Boltzmann equation is obtained, including both electron-electron and inelastic collisions. The result provides a simple formula for the total rate of excitation

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)

Few Issues Related to an Electrodynamic Exciter Control

OpenAIRE

Čala, M.

2015-01-01

There are multiple problems to solve when controlling an electromagnetic exciter for vibrations generation. Main challenge is to straighten a frequency response of an exciter which is normally not uniform due to resonances resulting from the mechanical construction of an exciter, specimen to test, or mounting fixture. This paper describes number of aspects to consider, which arose during implementation of the control system for small electrodynamic exciter on the Department of Control and Ins...

Modeling short-pulse laser excitation of dielectric materials

DEFF Research Database (Denmark)

Wædegaard, Kristian Juncher; Sandkamm, Ditte Både; Haahr-Lillevang, Lasse

2014-01-01

A theoretical description of ultrashort-pulse laser excitation of dielectric materials based on strong-field excitation in the Keldysh picture combined with a multiple-rateequation model for the electronic excitation including collisional processes is presented. The model includes light attenuation...

Electron-impact excitation of the potassium atom

International Nuclear Information System (INIS)

Phelps, J.O.; Solomon, J.E.; Korff, D.F.; Lin, C.C.; Lee, E.T.P.

1979-01-01

Absolute optical electron-impact excitation functions for 24 transitions of the sharp, principal, diffuse, and fundamental spectral series of potassium have been measured. The determination of the density of the potassium vapor in the collision chamber was made by measuring the degree of transmission, by the vapor, of potassium resonance radiation generated externally in a fluorescence cell. Direct excitation functions were determined for 14 states (5S, 6S, 7S, 8S, 4P, 5P, 6P, 7P, 3D, 5D, 6D, 5F, 6F, and 7F) with the aid of known radiative-transition probabilities. Theoretical calculations of these same 14 excitation functions, as well as 4D and 4F, were carried out by means of the Born approximation. The 4P, 5P, 5S, 3D, and 4D direct excitation functions at intermediate energies (10--25 eV) were also calculated by the method of multistate close coupling, neglecting projectile--target-electron exchange. The high-energy (above 100 eV) Born-approximation cross sections agree with the experimental results for 4P and for all S states, but are lower than experimental results, by 30--40%, for the D and F states. At intermediate energies the close-coupling excitation calculations agree well with the experimental excitation functions for 4P and 5P, but are significantly higher than experimental values for 5S and 3D. The discrepancies between the experimental and theoretical results are probably due to a combination of systematic experimental errors, errors in the available transition-probability values, and errors in the theoretical excitation functions introduced by the use of approximate excited-state wave functions (Hartree-Fock-Slater), by the neglect of projectile--target-electron exchange. The polarization of the 4P-4S and 3D-4P radiation produced by electron impact was measured, and the results were used to determine the direct excitation functions of the separate magnetic sublevels of the 4P state

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.

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

Roles of the Excitation in Harvesting Energy from Vibrations.

Directory of Open Access Journals (Sweden)

Hui Zhang

Full Text Available The study investigated the role of excitation in energy harvesting applications. While the energy ultimately comes from the excitation, it was shown that the excitation may not always behave as a source. When the device characteristics do not perfectly match the excitation, the excitation alternately behaves as a source and a sink. The extent to which the excitation behaves as a sink determines the energy harvesting efficiency. Such contradictory roles were shown to be dictated by a generalized phase defined as the instantaneous phase angle between the velocity of the device and the excitation. An inductive prototype device with a diamagnetically levitated seismic mass was proposed to take advantage of the well established phase changing mechanism of vibro-impact to achieve a broader device bandwidth. Results suggest that the vibro-impact can generate an instantaneous, significant phase shift in response velocity that switches the role of the excitation. If introduced properly outside the resonance zone it could dramatically increase the energy harvesting efficiency.

Electron impact excitation of the lowest doublet and quartet core-excited autoionizing states in Rb atoms

International Nuclear Information System (INIS)

Borovik, A; Roman, V; Zatsarinny, O; Bartschat, K

2013-01-01

Electron impact excitation of the (4p 5 5s 2 ) 2 P 3/2,1/2 and (4p 5 4d5s) 4 P 1/2,3/2,5/2 autoionizing states in rubidium atoms was studied experimentally by measuring the ejected-electron excitation functions and theoretically by employing a fully relativistic Dirac B-spline R-matrix (close-coupling) model. The experimental data were collected in an impact energy range from the respective excitation thresholds up to 50 eV with an incident electron energy resolution of 0.2 eV and an observation angle of 54.7°. Absolute values of the excitation cross sections were obtained by normalizing to the theoretical predictions. The observed near-threshold resonance structures were also analysed by comparison with theory. For the 2 P 3/2,1/2 doublet states, a detailed analysis of the R-matrix results reveals that the most intense resonances are related to odd-parity negative-ion states with dominant configurations 4p 5 5s5p 2 and 4p 5 4d5s6s. The measured excitation functions for the 2 P 1/2 and 4 P J states indicate a noticeable cascade population due to the radiative decay from high-lying autoionizing states. A comparative analysis with similar data for other alkali atoms is also presented.

Modeling pulsed excitation for gas-phase laser diagnostics

International Nuclear Information System (INIS)

Settersten, Thomas B.; Linne, Mark A.

2002-01-01

Excitation dynamics for pulsed optical excitation are described with the density-matrix equations and the rate equations for a two-level system. A critical comparison of the two descriptions is made with complete and consistent formalisms that are amenable to the modeling of applied laser-diagnostic techniques. General solutions, resulting from numerical integration of the differential equations describing the excitation process, are compared for collisional conditions that range from the completely coherent limit to the steady-state limit, for which the two formalisms are identical. This analysis demonstrates the failure of the rate equations to correctly describe the transient details of the excitation process outside the steady-state limit. However, reasonable estimates of the resultant population are obtained for nonsaturating (linear) excitation. This comparison provides the laser diagnostician with the means to evaluate the appropriate model for excitation through a simple picture of the breakdown of the rate-equation validity

Internal modes in high-temperature plasmas

International Nuclear Information System (INIS)

Crew, G.B.

1983-02-01

The linear stability of current-carrying toroidal plamsas is examined to determine the possibility of exciting global internal modes. The ideal magnetohydrodynamic (MHD) theory provides a useful framework for the analysis of these modes, which involve a kinking of the central portion of the plasma column. Non-ideal effects can also be important, and these are treated for high-temperature regimes where the plasma is collisionless

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

Sensory tricks and brain excitability in cervical dystonia: a transcranial magnetic stimulation study.

Science.gov (United States)

Amadio, Stefano; Houdayer, Elise; Bianchi, Francesca; Tesfaghebriel Tekle, Habtom; Urban, Ivan Pietro; Butera, Calogera; Guerriero, Roberta; Cursi, Marco; Leocani, Letizia; Comi, Giancarlo; Del Carro, Ubaldo

2014-08-01

Sensory tricks such as touching the face with fingertips often improve cervical dystonia [CD]. This study is to determine whether sensory tricks modulate motor cortex excitability, assessed by paired-pulse transcranial magnetic stimulation [p-pTMS]. Eight patients with rotational CD underwent p-pTMS, at rest and when the sensory trick was applied. To test intracortical inhibition [ICI] and facilitation [ICF], the amplitude ratio between conditioned and unconditioned cortical motor evoked potentials was measured at several interstimulus intervals (ISI 1, 3, 15, and 20 ms) and compared with controls mimicking patients' sensory tricks. At rest, a significant ICF enhancement was found at ISIs 15 through 20 in patients compared with controls, whereas no significant ICI changes were observed. Sensory tricks significantly reduced the abnormal ICF in patients and did not induce any change in controls. In our CD patients, sensory tricks seem to improve dystonia through an inhibitory effect on motor cortex excitability. © 2014 International Parkinson and Movement Disorder Society.

Excited, bound and resonant positron-atom systems

International Nuclear Information System (INIS)

Bromley, M W J; Mitroy, J

2010-01-01

Calculations have demonstrated that eleven neutral atoms can bind positrons, while many more can bind positronium. This is a short review of recent progress made in understanding some of the underlying mechanisms. The emphasis here being on configuration interaction calculations with excited state configurations. These have demonstrated the existence of a 2 P o excited state of e + Ca, which consists predominantly of a positronium cluster orbiting the Ca + ion in the L = 1 partial wave. Preliminary results are presented of excited state positron binding to a model alkali atom, where the excited 1 P o states are stable over a limited region. Implications for the unnatural parity, 2,4 S o , states of PsH, LiPs, NaPs and KPs are also discussed. The e + Mg, e + Cu, e + Zn and e + Cd systems show a lack of a 2 P o excited state, each instead possessing a low-energy p-wave shape resonance of varying strength.

Getting super-excited with modified dispersion relations

Energy Technology Data Exchange (ETDEWEB)

Ashoorioon, Amjad; Casadio, Roberto [INFN—Sezione di Bologna, viale B. Pichat 6/2, I-40127 Bologna (Italy); Geshnizjani, Ghazal; Kim, Hyung J., E-mail: amjad.ashoorioon@bo.infn.it, E-mail: roberto.casadio@bo.infn.it, E-mail: ggeshniz@uwaterloo.ca, E-mail: h268kim@uwaterloo.ca [Department of Applied Mathematics, University of Waterloo Waterloo, Ontario, N2L 3G1 (Canada)

2017-09-01

We demonstrate that in some regions of parameter space, modified dispersion relations can lead to highly populated excited states, which we dub as 'super-excited' states. In order to prepare such super-excited states, we invoke dispersion relations that have negative slope in an interim sub-horizon phase at high momenta. This behaviour of quantum fluctuations can lead to large corrections relative to the Bunch-Davies power spectrum, which mimics highly excited initial conditions. We identify the Bogolyubov coefficients that can yield these power spectra. In the course of this computation, we also point out the shortcomings of the gluing method for evaluating the power spectrum and the Bogolyubov coefficients. As we discuss, there are other regions of parameter space, where the power spectrum does not get modified. Therefore, modified dispersion relations can also lead to so-called 'calm excited states'. We conclude by commenting on the possibility of obtaining these modified dispersion relations within the Effective Field Theory of Inflation.

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

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...

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...

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...

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).

Probing changes in corticospinal excitability following theta burst stimulation of the human primary motor cortex.

Science.gov (United States)

Goldsworthy, Mitchell R; Vallence, Ann-Maree; Hodyl, Nicolette A; Semmler, John G; Pitcher, Julia B; Ridding, Michael C

2016-01-01

To determine whether the intensity of transcranial magnetic stimulation (TMS) used to probe changes in corticospinal excitability influences the measured plasticity response to theta burst stimulation (TBS) of the human primary motor cortex. Motor evoked potential (MEP) input/output (I/O) curves were recorded before and following continuous TBS (cTBS) (Experiment 1; n=18) and intermittent TBS (iTBS) (Experiment 2; n=18). The magnitude and consistency of MEP depression induced by cTBS was greatest when probed using stimulus intensities at or above 150% of resting motor threshold (RMT). In contrast, facilitation of MEPs following iTBS was strongest and most consistent at 110% of RMT. The plasticity response to both cTBS and iTBS is influenced by the stimulus intensity used to probe the induced changes in corticospinal excitability. The results highlight the importance of the test stimulus intensity used to assess TBS-induced changes in corticospinal excitability when interpreting neuroplasticity data, and suggest that a number of test intensities may be required to reliably probe the plasticity response. Copyright © 2015 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

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

Electronic excitations in fast ion-solid collisions

International Nuclear Information System (INIS)

Burgdoerfer, J.

1990-01-01

We review recent developments in the study of electronic excitation of projectiles in fast ion-solid collisions. Our focus will be primarily on theory but experimental advances will also be discussed. Topics include the evidence for velocity-dependent thresholds for the existence of bound states, wake-field effects on excited states, the electronic excitation of channeled projectiles, transport phenomena, and the interaction of highly charged ions with surfaces. 44 refs., 14 figs

Solvent-dependent excited-state hydrogen transfer and intersystem crossing in 2-(2′-hydroxyphenyl)-benzothiazole

KAUST Repository

Aly, Shawkat Mohammede

2015-02-12

The excited-state intramolecular hydrogen transfer (ESIHT) of 2-(2′-hydroxyphenyl) benzothiazole (HBT) has been investigated in a series of nonpolar, polar aprotic, and polar protic solvents. A variety of state-of-the-art experimental methods were employed, including femto- and nanosecond transient absorption and fluorescence upconversion spectroscopy with broadband capabilities. We show that the dynamics and mechanism of ESIHT of the singlet excited HBT are strongly solvent-dependent. In nonpolar solvents, the data demonstrate that HBT molecules adopt a closed form stabilized by O-H⋯N chelated hydrogen bonds with no twisting angle, and the photoinduced H transfer occurs within 120 fs, leading to the formation of a keto tautomer. In polar solvents, owing to dipole-dipole cross talk and hydrogen bonding interactions, the H transfer process is followed by ultrafast nonradiative deactivation channels, including ultrafast internal conversion (IC) and intersystem crossing (ISC). This is likely to be driven by the twisting motion around the C-C bond between the hydroxyphenyl and thiazole moieties, facilitating the IC back to the enol ground state or to the keto triplet state. In addition, our femtosecond time-resolved fluorescence experiments indicate, for the first time, that the lifetime of the enol form in ACN is approximately 280 fs. This observation indicates that the solvent plays a crucial role in breaking the H bond and deactivating the excited state of the HBT. Interestingly, the broadband transient absorption and fluorescence up-conversion data clearly demonstrate that the intermolecular proton transfer from the excited HBT to the DMSO solvent is about 190 fs, forming the HBT anion excited state.

Solvent-dependent excited-state hydrogen transfer and intersystem crossing in 2-(2′-hydroxyphenyl)-benzothiazole

KAUST Repository

Aly, Shawkat Mohammede; Usman, Anwar; Alzayer, Maytham; Hamdi, Ghada A.; Alarousu, Erkki; Mohammed, Omar F.

2015-01-01

The excited-state intramolecular hydrogen transfer (ESIHT) of 2-(2′-hydroxyphenyl) benzothiazole (HBT) has been investigated in a series of nonpolar, polar aprotic, and polar protic solvents. A variety of state-of-the-art experimental methods were employed, including femto- and nanosecond transient absorption and fluorescence upconversion spectroscopy with broadband capabilities. We show that the dynamics and mechanism of ESIHT of the singlet excited HBT are strongly solvent-dependent. In nonpolar solvents, the data demonstrate that HBT molecules adopt a closed form stabilized by O-H⋯N chelated hydrogen bonds with no twisting angle, and the photoinduced H transfer occurs within 120 fs, leading to the formation of a keto tautomer. In polar solvents, owing to dipole-dipole cross talk and hydrogen bonding interactions, the H transfer process is followed by ultrafast nonradiative deactivation channels, including ultrafast internal conversion (IC) and intersystem crossing (ISC). This is likely to be driven by the twisting motion around the C-C bond between the hydroxyphenyl and thiazole moieties, facilitating the IC back to the enol ground state or to the keto triplet state. In addition, our femtosecond time-resolved fluorescence experiments indicate, for the first time, that the lifetime of the enol form in ACN is approximately 280 fs. This observation indicates that the solvent plays a crucial role in breaking the H bond and deactivating the excited state of the HBT. Interestingly, the broadband transient absorption and fluorescence up-conversion data clearly demonstrate that the intermolecular proton transfer from the excited HBT to the DMSO solvent is about 190 fs, forming the HBT anion excited state.

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

Associative ionization of two laser excited Na atoms

International Nuclear Information System (INIS)

Meijer, H.A.J.

1988-01-01

An investigation into the associative ionization of two sodium atoms excited by polarized laser beams is described. It was possible to excite the Na atoms in a velocity-selective way by exploiting the Doppler effect. The excitation of Na to the 3 2 P 3/2 , F=3 level is discussed on the basis of so-called saturation curves. Experiments with seven different combinations of polarization of the two exciting laser beams are described and the results discussed. 86 refs.; 53 figs.; 6 tabs

Spectroscopy and reactions of vibrationally excited transient molecules

Energy Technology Data Exchange (ETDEWEB)

Dai, H.L. [Univ. of Pennsylvania, Philadelphia (United States)

1993-12-01

Spectroscopy, energy transfer and reactions of vibrationally excited transient molecules are studied through a combination of laser-based excitation techniques and efficient detection of emission from the energized molecules with frequency and time resolution. Specifically, a Time-resolved Fourier Transform Emission Spectroscopy technique has been developed for detecting dispersed laser-induced fluorescence in the IR, visible and UV regions. The structure and spectroscopy of the excited vibrational levels in the electronic ground state, as well as energy relaxation and reactions induced by specific vibronic excitations of a transient molecule can be characterized from time-resolved dispersed fluorescence in the visible and UV region. IR emissions from highly vibrational excited levels, on the other hand, reveal the pathways and rates of collision induced vibrational energy transfer.

The photodissociation and reaction dynamics of vibrationally excited molecules

Energy Technology Data Exchange (ETDEWEB)

Crim, F.F. [Univ. of Wisconsin, Madison (United States)

1993-12-01

This research determines the nature of highly vibrationally excited molecules, their unimolecular reactions, and their photodissociation dynamics. The goal is to characterize vibrationally excited molecules and to exploit that understanding to discover and control their chemical pathways. Most recently the author has used a combination of vibrational overtone excitation and laser induced fluorescence both to characterize vibrationally excited molecules and to study their photodissociation dynamics. The author has also begun laser induced grating spectroscopy experiments designed to obtain the electronic absorption spectra of highly vibrationally excited molecules.

201Hg excitation in plasma produced by laser

International Nuclear Information System (INIS)

Comet, Maxime

2014-01-01

The use of high power lasers allows the study of the properties of matter in extreme conditions of temperature and density. Indeed, the interaction of a power laser and a target creates a plasma in which the temperature is high enough to reach important degrees of ionization. These conditions can allow the excitation of the nucleus. A nucleus of interest to study the processes of nuclear excitation is the 201 Hg. This work aims to design an experiment where the 201 Hg excitation will be observed in a plasma produced by a high power laser. The first part of this manuscript presents the calculation of the expected nuclear excitation rates in the plasma. For about ten years, nuclear excitation rates have been calculated using the average atom model. To validate this model a code named ADAM (French acronym for Beyond The Average Atom Model) was developed to calculate the nuclear excitation rates under the DCA (Detailed Configuration Accounting) hypothesis. ADAM allows us to deduce the thermo dynamical domain where the nuclear excitation rates determined with the average atom model are relevant. The second part of this manuscript presents the coupling of the excitation rate calculation with a hydrodynamic code to calculate the number of excited nuclei produced in one laser shot for different laser intensity. Finally, in the last part, first experimental approaches which will be used to design an experiment on a laser installation are presented. These approaches are based on the detection and determination of the amount of multicharged ions obtained far from the target (∼80 cm). For this purpose, an electrostatic analyzer was used. (author) [fr

Coherence, energy and charge transfers in de-excitation pathways of electronic excited state of biomolecules in photosynthesis

DEFF Research Database (Denmark)

Bohr, Henrik; Malik, F. Bary

2013-01-01

The observed multiple de-excitation pathways of photo-absorbed electronic excited state in the peridinin–chlorophyll complex, involving both energy and charge transfers among its constituents, are analyzed using the bio-Auger (B-A) theory. It is also shown that the usually used F¨orster–Dexter...

On Emulation of Flueric Devices in Excitable Chemical Medium.

Science.gov (United States)

Adamatzky, Andrew

2016-01-01

Flueric devices are fluidic devices without moving parts. Fluidic devices use fluid as a medium for information transfer and computation. A Belousov-Zhabotinsky (BZ) medium is a thin-layer spatially extended excitable chemical medium which exhibits travelling excitation wave-fronts. The excitation wave-fronts transfer information. Flueric devices compute via jets interaction. BZ devices compute via excitation wave-fronts interaction. In numerical model of BZ medium we show that functions of key flueric devices are implemented in the excitable chemical system: signal generator, and, xor, not and nor Boolean gates, delay elements, diodes and sensors. Flueric devices have been widely used in industry since late 1960s and are still employed in automotive and aircraft technologies. Implementation of analog of the flueric devices in the excitable chemical systems opens doors to further applications of excitation wave-based unconventional computing in soft robotics, embedded organic electronics and living technologies.

On Emulation of Flueric Devices in Excitable Chemical Medium.

Directory of Open Access Journals (Sweden)

Andrew Adamatzky

Full Text Available Flueric devices are fluidic devices without moving parts. Fluidic devices use fluid as a medium for information transfer and computation. A Belousov-Zhabotinsky (BZ medium is a thin-layer spatially extended excitable chemical medium which exhibits travelling excitation wave-fronts. The excitation wave-fronts transfer information. Flueric devices compute via jets interaction. BZ devices compute via excitation wave-fronts interaction. In numerical model of BZ medium we show that functions of key flueric devices are implemented in the excitable chemical system: signal generator, and, xor, not and nor Boolean gates, delay elements, diodes and sensors. Flueric devices have been widely used in industry since late 1960s and are still employed in automotive and aircraft technologies. Implementation of analog of the flueric devices in the excitable chemical systems opens doors to further applications of excitation wave-based unconventional computing in soft robotics, embedded organic electronics and living technologies.

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.)

Multiple photoionization from 3p excitation of Kr and 4p excitation of Xe

International Nuclear Information System (INIS)

Hayaishi, T.

1986-01-01

The photoionization cross sections for multiply charged ions produced by 3p excitation of Kr and 4p excitation of Xe have been obtained by means of a time-of-flight mass spectrometer and synchrotron radiation. It is found that the main formation of doubly to quadruply charged ions in both Kr and Xe is caused from the each initial p-hole state through a Coster-Kronig transition followed by Auger of double Auger processes. The formation of singly charged ions in these excitation energy regions is caused by direct photoionization from outermost shell electrons in both Kr and Xe. Triply charged ions are prominently produced among the multiply charged ions. The quadruple photoionization cross sections show clearly the structures due to the Rydberg series, 3p -1 nl of Kr and 4p -1 nl of Xe. Their main structures were assigned to the 3p -1 nd series in Kr and the 4p -1 nd series in Xe. (orig.)

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

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)

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...

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

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

THE CHEMISTRY OF VIBRATIONALLY EXCITED H2 IN THE INTERSTELLAR MEDIUM

International Nuclear Information System (INIS)

Agundez, M.; Roueff, E.; Goicoechea, J. R.; Cernicharo, J.; Faure, A.

2010-01-01

The internal energy available in vibrationally excited H 2 molecules can be used to overcome or diminish the activation barrier of various chemical reactions of interest for molecular astrophysics. In this paper, we investigate in detail the impact on the chemical composition of interstellar clouds of the reactions of vibrationally excited H 2 with C + , He + , O, OH, and CN, based on the available chemical kinetics data. It is found that the reaction of H 2 (v>0) and C + has a profound impact on the abundances of some molecules, especially CH + , which is a direct product and is readily formed in astronomical regions with fractional abundances of vibrationally excited H 2 , relative to the ground state H 2 , in excess of ∼10 -6 , independently of whether the gas is hot or not. The effects of these reactions on the chemical composition of the diffuse clouds ζOph and HD 34078, the dense photon-dominated region (PDR) Orion Bar, the planetary nebula NGC 7027, and the circumstellar disk around the B9 star HD 176386 are investigated through PDR models. We find that formation of CH + is especially favored in dense and highly FUV illuminated regions such as the Orion Bar and the planetary nebula NGC 7027, where column densities in excess of 10 13 cm -2 are predicted. In diffuse clouds, however, this mechanism is found to be not efficient enough to form CH + with a column density close to the values derived from astronomical observations.

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....

Excited, bound and resonant positron-atom systems

Energy Technology Data Exchange (ETDEWEB)

Bromley, M W J [Department of Physics and Computational Science Research Center, San Diego State University, San Diego CA 92182 (United States); Mitroy, J, E-mail: mbromley@physics.sdsu.ed [ARC Centre for Antimatter-Matter Studies and Faculty of Education, Health and Science, Charles Darwin University, Darwin NT 0909 (Australia)

2010-01-01

Calculations have demonstrated that eleven neutral atoms can bind positrons, while many more can bind positronium. This is a short review of recent progress made in understanding some of the underlying mechanisms. The emphasis here being on configuration interaction calculations with excited state configurations. These have demonstrated the existence of a {sup 2}P{sup o} excited state of e{sup +}Ca, which consists predominantly of a positronium cluster orbiting the Ca{sup +} ion in the L = 1 partial wave. Preliminary results are presented of excited state positron binding to a model alkali atom, where the excited {sup 1}P{sup o} states are stable over a limited region. Implications for the unnatural parity, {sup 2,4}S{sup o}, states of PsH, LiPs, NaPs and KPs are also discussed. The e{sup +}Mg, e{sup +}Cu, e{sup +}Zn and e{sup +}Cd systems show a lack of a {sup 2}P{sup o} excited state, each instead possessing a low-energy p-wave shape resonance of varying strength.

Non-adiabatic Excited State Molecule Dynamics Modeling of Photochemistry and Photophysics of Materials

Energy Technology Data Exchange (ETDEWEB)

Nelson, Tammie Renee [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Tretiak, Sergei [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

2017-01-06

Understanding and controlling excited state dynamics lies at the heart of all our efforts to design photoactive materials with desired functionality. This tailor-design approach has become the standard for many technological applications (e.g., solar energy harvesting) including the design of organic conjugated electronic materials with applications in photovoltaic and light-emitting devices. Over the years, our team has developed efficient LANL-based codes to model the relevant photophysical processes following photoexcitation (spatial energy transfer, excitation localization/delocalization, and/or charge separation). The developed approach allows the non-radiative relaxation to be followed on up to ~10 ps timescales for large realistic molecules (hundreds of atoms in size) in the realistic solvent dielectric environment. The Collective Electronic Oscillator (CEO) code is used to compute electronic excited states, and the Non-adiabatic Excited State Molecular Dynamics (NA-ESMD) code is used to follow the non-adiabatic dynamics on multiple coupled Born-Oppenheimer potential energy surfaces. Our preliminary NA-ESMD simulations have revealed key photoinduced mechanisms controlling competing interactions and relaxation pathways in complex materials, including organic conjugated polymer materials, and have provided a detailed understanding of photochemical products and intermediates and the internal conversion process during the initiation of energetic materials. This project will be using LANL-based CEO and NA-ESMD codes to model nonradiative relaxation in organic and energetic materials. The NA-ESMD and CEO codes belong to a class of electronic structure/quantum chemistry codes that require large memory, “long-queue-few-core” distribution of resources in order to make useful progress. The NA-ESMD simulations are trivially parallelizable requiring ~300 processors for up to one week runtime to reach a meaningful restart point.

Lifetime and g-factor measurements of excited states using Coulomb excitation and alpha transfer reactions

Energy Technology Data Exchange (ETDEWEB)

Guevara, Z. E., E-mail: zjguevaram@unal.edu.co; Torres, D. A., E-mail: datorresg@unal.edu.co [Physics Department, Universidad Nacional de Colombia, Bogotá D.C. (Colombia)

2016-07-07

In this contribution the challenges in the use of a setup to simultaneously measure lifetimes and g-factor values will be presented. The simultaneous use of the transient field technique and the Doppler Shift Attenuation Method, to measure magnetic moments and lifetimes respectively, allows to obtain a complete characterization of the currents of nucleons and the deformation in excited states close to the ground state. The technique is at the moment limited to Coulomb excitation and alpha-transfer reactions, what opens an interesting perspective to consider this type of experiments with radioactive beams. The use of deep-inelastic and fusion-evaporation reactions will be discussed. An example of a setup that makes use of a beam of {sup 106}Cd to study excited states of {sup 110}Sn and the beam nuclei itself will be presented.

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.

Room temperature excitation spectroscopy of single quantum dots

Directory of Open Access Journals (Sweden)

Christian Blum

2011-08-01

Full Text Available We report a single molecule detection scheme to investigate excitation spectra of single emitters at room temperature. We demonstrate the potential of single emitter photoluminescence excitation spectroscopy by recording excitation spectra of single CdSe nanocrystals over a wide spectral range of 100 nm. The spectra exhibit emission intermittency, characteristic of single emitters. We observe large variations in the spectra close to the band edge, which represent the individual heterogeneity of the observed quantum dots. We also find specific excitation wavelengths for which the single quantum dots analyzed show an increased propensity for a transition to a long-lived dark state. We expect that the additional capability of recording excitation spectra at room temperature from single emitters will enable insights into the photophysics of emitters that so far have remained inaccessible.

Broad-Band Analysis of Polar Motion Excitations

Science.gov (United States)

Chen, J.

2016-12-01

Earth rotational changes, i.e. polar motion and length-of-day (LOD), are driven by two types of geophysical excitations: 1) mass redistribution within the Earth system, and 2) angular momentum exchange between the solid Earth (more precisely the crust) and other components of the Earth system. Accurate quantification of Earth rotational excitations has been difficult, due to the lack of global-scale observations of mass redistribution and angular momentum exchange. The over 14-years time-variable gravity measurements from the Gravity Recovery and Climate Experiment (GRACE) have provided a unique means for quantifying Earth rotational excitations from mass redistribution in different components of the climate system. Comparisons between observed Earth rotational changes and geophysical excitations estimated from GRACE, satellite laser ranging (SLR) and climate models show that GRACE-derived excitations agree remarkably well with polar motion observations over a broad-band of frequencies. GRACE estimates also suggest that accelerated polar region ice melting in recent years and corresponding sea level rise have played an important role in driving long-term polar motion as well. With several estimates of polar motion excitations, it is possible to estimate broad-band noise variance and noise power spectra in each, given reasonable assumptions about noise independence. Results based on GRACE CSR RL05 solutions clearly outperform other estimates with the lowest noise levels over a broad band of frequencies.

Low-lying excited states by constrained DFT

Science.gov (United States)

Ramos, Pablo; Pavanello, Michele

2018-04-01

Exploiting the machinery of Constrained Density Functional Theory (CDFT), we propose a variational method for calculating low-lying excited states of molecular systems. We dub this method eXcited CDFT (XCDFT). Excited states are obtained by self-consistently constraining a user-defined population of electrons, Nc, in the virtual space of a reference set of occupied orbitals. By imposing this population to be Nc = 1.0, we computed the first excited state of 15 molecules from a test set. Our results show that XCDFT achieves an accuracy in the predicted excitation energy only slightly worse than linear-response time-dependent DFT (TDDFT), but without incurring into problems of variational collapse typical of the more commonly adopted ΔSCF method. In addition, we selected a few challenging processes to test the limits of applicability of XCDFT. We find that in contrast to TDDFT, XCDFT is capable of reproducing energy surfaces featuring conical intersections (azobenzene and H3) with correct topology and correct overall energetics also away from the intersection. Venturing to condensed-phase systems, XCDFT reproduces the TDDFT solvatochromic shift of benzaldehyde when it is embedded by a cluster of water molecules. Thus, we find XCDFT to be a competitive method among single-reference methods for computations of excited states in terms of time to solution, rate of convergence, and accuracy of the result.

Investigation of the spectroscopy and relaxation dynamics of benzaldehyde using molecular orbital calculations and laser ionization time-of-flight mass spectroscopy

Science.gov (United States)

da Silva, Maria Cristina Rodrigues

1998-11-01

Molecular orbital methods and laser ionization mass spectrometry measurements are used to investigate the spectroscopy and relaxation dynamics of benzaldehyde following excitation to its S2(/pi/pi/sp/*) state. Energies, equilibrium geometries and vibrational frequencies of ground and low-lying excited states of benzaldehyde neutral and cation determined by ab initio calculations provide a theoretical description of the electronic spectroscopy of benzaldehyde and of the changes occurring on excitation and ionization. The S2(/pi/pi/sp/*)[/gets]S0 excitation spectrum of jet-cooled benzaldehyde acquired using two-color laser ionization mass spectrometry techniques is interpreted with the aid of these calculations. The spectrum is dominated by the origin band and by transitions involving some of the ring modes consistent with the results of the molecular orbital calculations that indicate that the major geometric changes on excitation to S2 are located in the aromatic ring. Ten fundamental vibrations of the S2(/pi/pi/sp/*) state are assigned. The dissociation dynamics of benzaldehyde into benzene and carbon monoxide following excitation to its S2(/pi/pi/sp/*) state are investigated under jet- cooled conditions by two-color laser ionization mass spectrometry using a pump-probe technique. This experimental arrangement allows monitoring the benzaldehyde reactant and the benzene product ion signals as a function of the time delay between the excitation and ionization steps. A kinetic model is proposed to explain the observed biexponential decay of the benzaldehyde signal and the single exponential growth of the benzene product signal in terms of a sequential decay of two excited states of benzaldehyde, one of which leads to formation of benzene molecules in its lowest triplet state. Reactant disappearance and product appearance rates are determined for a number of vibronic transitions of the S2 state. They are found to increase with excitation energy without any indication

Electron Impact Excitation and Dielectronic Recombination of Highly Charged Tungsten Ions

Directory of Open Access Journals (Sweden)

Zhongwen Wu

2015-11-01

Full Text Available Electron impact excitation (EIE and dielectronic recombination (DR of tungsten ions are basic atomic processes in nuclear fusion plasmas of the International Thermonuclear Experimental Reactor (ITER tokamak. Detailed investigation of such processes is essential for modeling and diagnosing future fusion experiments performed on the ITER. In the present work, we studied total and partial electron-impact excitation (EIE and DR cross-sections of highly charged tungsten ions by using the multiconfiguration Dirac–Fock method. The degrees of linear polarization of the subsequent X-ray emissions from unequally-populated magnetic sub-levels of these ions were estimated. It is found that the degrees of linear polarization of the same transition lines, but populated respectively by the EIE and DR processes, are very different, which makes diagnosis of the formation mechanism of X-ray emissions possible. In addition, with the help of the flexible atomic code on the basis of the relativistic configuration interaction method, DR rate coefficients of highly charged W37+ to W46+ ions are also studied, because of the importance in the ionization equilibrium of tungsten plasmas under running conditions of the ITER.

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

Double-electron excitation above Xe K-edge

International Nuclear Information System (INIS)

Ito, Y.; Tochio, T.; Vlaicu, A.M.; Mutaguchi, K.; OhHashi, H.; Shigeoka, N.; Nakata, Y.; Akahama, Y.; Uruga, T.; Emura, Sh.

2000-01-01

When X-rays fall on any substance, whether solid, liquid, or gaseous, a photoabsorption occurs. Photoabsorption in atoms has been generally treated as a single-electron excitation process. However, the existence of the multi-electron excitation process, where the removal of a core electron by photoabsorption causes excitation of additional electrons in the same atoms, has been known in x-ray absorption spectra for a long time. In x-ray absorption spectra, experimental investigations of the shake processes in inner-shell ionization phenomena have been performed by detecting discontinuities. The shake effect which is a consequence of rearrangement of the atomic electrons, occurs in association with inner-shell excitation and ionization phenomena in x-ray absorption. The shake process has been studied extensively in various gases, because it is usually considered that the measurement of the multi-electron excitation is only possible for monatomic gases or vapors. The x-ray absorption spectra in Kr gas were measured by Ito et al. in order to observe precisely x-ray absorption spectra and to investigate the multi-electron excitation cross sections in Kr as a function of photon energy using synchrotron radiation. However, no suitable measured K x-ray absorption spectra was available to elucidate the shake processes. In the present work, the photoabsorption cross sections in Xe have been precisely measured in order to determine the features on the shake processes resulting from multiple electron excitations as a function of photon energy. Double-electron transitions of [1s4d], [1s4p], [1s4s], and [1s3d] are first detected. (author)

Study on Excitation-triggered Damage Mechanism in Perilous Rock

Science.gov (United States)

Chen, Hongkai; Wang, Shengjuan

2017-12-01

Chain collapse is easy to happen for perilous rock aggregate locating on steep high slope, and one of the key scientific problems is the damage mechanism of perilous rock under excitation action at perilous rock rupture. This paper studies excitation-triggered damage mechanism in perilous rock by wave mechanics, which gives three conclusions. Firstly, when only the normal incidence attenuation spread of excitation wave is considered, while the energy loss is ignored for excitation wave to spread in perilous rock aggregate, the paper establishes one method to calculate peak velocity when excitation wave passes through boundary between any two perilous rock blocks in perilous rock aggregate. Secondly, following by Sweden and Canmet criteria, the paper provides one wave velocity criterion for excitation-triggered damage in the aggregate. Thirdly, assuming double parameters of volume strain of cracks or fissures in rock meet the Weibull distribution, one method to estimate micro-fissure in excitation-triggered damage zone in perilous rock aggregate is established. The studies solve the mechanical description problem for excitation-triggered damage in perilous rock, which is valuable in studies on profoundly rupture mechanism.

Room-temperature atomic layer deposition of ZrO{sub 2} using tetrakis(ethylmethylamino)zirconium and plasma-excited humidified argon

Energy Technology Data Exchange (ETDEWEB)

Kanomata, K. [Graduate School of Science and Engineering, Yamagata University, 4-3-16 Jonan, Yonezawa 992-8510 (Japan); Japan Society for the Promotion of Science, 5-3-1 Kojimachi, Chiyoda-ku, Tokyo 102-0083 (Japan); Tokoro, K.; Imai, T.; Pansila, P.; Miura, M.; Ahmmad, B.; Kubota, S.; Hirahara, K. [Graduate School of Science and Engineering, Yamagata University, 4-3-16 Jonan, Yonezawa 992-8510 (Japan); Hirose, F., E-mail: fhirose@yz.yamagata-u.ac.jp [Graduate School of Science and Engineering, Yamagata University, 4-3-16 Jonan, Yonezawa 992-8510 (Japan)

2016-11-30

Highlights: • RT-ALD of ZrO{sub 2} is developed using TEMAZ and plasma-excited humidified argon. • The plasma-excited humidified argon is effective in oxidizing the TEMAZ saturated ZrO{sub 2}. • We discuss the reaction mechanism of the RT-ZrO{sub 2} ALD. - Abstract: Room-temperature atomic layer deposition (ALD) of ZrO{sub 2} is developed with tetrakis(ethylmethylamino)zirconium (TEMAZ) and a plasma-excited humidified argon. A growth per cycle of 0.17 nm/cycle at room temperature is confirmed, and the TEMAZ adsorption and its oxidization on ZrO{sub 2} are characterized by IR absorption spectroscopy with a multiple internal reflection mode. TEMAZ is saturated on a ZrO{sub 2} surface with exposures exceeding ∼2.0 × 10{sup 5} Langmuir (1 Langmuir = 1.0 × 10{sup −6} Torr s) at room temperature, and the plasma-excited humidified argon is effective in oxidizing the TEMAZ-adsorbed ZrO{sub 2} surface. The IR absorption spectroscopy suggests that Zr-OH works as an adsorption site for TEMAZ. The reaction mechanism of room-temperature ZrO{sub 2} ALD is discussed in this paper.

A note on calm excited states of inflation

International Nuclear Information System (INIS)

Ashoorioon, Amjad; Shiu, Gary

2011-01-01

We identify a two-parameter family of excited states within slow-roll inflation for which either the corrections to the two-point function or the characteristic signatures of excited states in the three-point function — i.e. the enhancement for the flattened momenta configurations– are absent. These excited states may nonetheless violate the adiabaticity condition maximally. We dub these initial states of inflation calm excited states. We show that these two sets do not intersect, i.e., those that leave the power-spectrum invariant can be distinguished from their bispectra, and vice versa. The same set of calm excited states that leave the two-point function invariant for slow-roll inflation, do the same task for DBI inflation. However, at the level of three-point function, the calm excited states whose flattened configuration signature is absent for slow-roll inflation, will lead to an enhancement for DBI inflation generally, although the signature is smaller than what suggested by earlier analysis. This example also illustrates that imposing the Wronskian condition is important for obtaining a correct estimate of the non-Gaussian signatures

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

Dissociation dynamics of anionic and excited neutral fragments of gaseous SiCl4 following Cl 2p and Si 2p core-level excitations

International Nuclear Information System (INIS)

Chen, J M; Lu, K T; Lee, J M; Chou, T L; Chen, H C; Chen, S A; Haw, S C; Chen, T H

2008-01-01

The state-selective dissociation dynamics for anionic and excited neutral fragments of gaseous SiCl 4 following Cl 2p and Si 2p core-level excitations were characterized by combining measurements of the photon-induced anionic dissociation, x-ray absorption and UV/visible dispersed fluorescence. The transitions of core electrons to high Rydberg states/doubly excited states in the vicinity of both Si 2p and Cl 2p ionization thresholds of gaseous SiCl 4 lead to a remarkably enhanced production of anionic, Si - and Cl - , fragments and excited neutral atomic, Si*, fragments. This enhancement via core-level excitation near the ionization threshold of gaseous SiCl 4 is explained in terms of the contributions from the Auger decay of doubly excited states, shake-modified resonant Auger decay, or/and post-collision interaction. These complementary results provide insight into the state-selective anionic and excited neutral fragmentation of gaseous molecules via core-level excitation.

Highlights in light-baryon spectroscopy and searches for gluonic excitations

Science.gov (United States)

Crede, Volker

2016-01-01

The spectrum of excited hadrons - mesons and baryons - serves as an excellent probe of quantum chromodynamics (QCD), the fundamental theory of the strong interaction. The strong coupling however makes QCD challenging. It confines quarks and breaks chiral symmetry, thus providing us with the world of light hadrons. Highly-excited hadronic states are sensitive to the details of quark confinement, which is only poorly understood within QCD. This is the regime of non-perturbative QCD and it is one of the key issues in hadronic physics to identify the corresponding internal degrees of freedom and how they relate to strong coupling QCD. The quark model suggests mesons are made of a constituent quark and an antiquark and baryons consist of three such quarks. QCD predicts other forms of matter. What is the role of glue? Resonances with large gluonic components are predicted as bound states by QCD. The lightest hybrid mesons with exotic quantum numbers are estimated to have masses in the range from 1 to 2 GeV/c2 and are well in reach of current experimental programs. At Jefferson Laboratory (JLab) and other facilities worldwide, the high-energy electron and photon beams present a remarkably clean probe of hadronic matter, providing an excellent microscope for examining atomic nuclei and the strong nuclear force.

Vector boson excitations near deconfined quantum critical points.

Science.gov (United States)

Huh, Yejin; Strack, Philipp; Sachdev, Subir

2013-10-18

We show that the Néel states of two-dimensional antiferromagnets have low energy vector boson excitations in the vicinity of deconfined quantum critical points. We compute the universal damping of these excitations arising from spin-wave emission. Detection of such a vector boson will demonstrate the existence of emergent topological gauge excitations in a quantum spin system.

Competition between excited core states and 1homega single-particle excitations at comparable energies in {sup 207}Pb from photon scattering

Energy Technology Data Exchange (ETDEWEB)

Pietralla, N., E-mail: pietralla@ikp.tu-darmstadt.d [Institut fuer Kernphysik, Technische Universitaet Darmstadt, 64289 Darmstadt (Germany); Nuclear Structure Laboratory, SUNY at Stony Brook, Stony Brook, NY 11794-3800 (United States); Institut fuer Kernphysik, Universitaet zu Koeln, 50937 Koeln (Germany); Li, T.C. [Nuclear Structure Laboratory, SUNY at Stony Brook, Stony Brook, NY 11794-3800 (United States); Fritzsche, M. [Institut fuer Kernphysik, Technische Universitaet Darmstadt, 64289 Darmstadt (Germany); Ahmed, M.W. [Triangle Universities Nuclear Laboratory (TUNL), Duke University, Durham, NC 27708 (United States); Ahn, T.; Costin, A. [Institut fuer Kernphysik, Technische Universitaet Darmstadt, 64289 Darmstadt (Germany); Nuclear Structure Laboratory, SUNY at Stony Brook, Stony Brook, NY 11794-3800 (United States); Institut fuer Kernphysik, Universitaet zu Koeln, 50937 Koeln (Germany); Enders, J. [Institut fuer Kernphysik, Technische Universitaet Darmstadt, 64289 Darmstadt (Germany); Li, J. [Duke Free Electron Laser Laboratory (DFELL), Duke University, Durham, NC 27708 (United States); Mueller, S.; Neumann-Cosel, P. von [Institut fuer Kernphysik, Technische Universitaet Darmstadt, 64289 Darmstadt (Germany); Pinayev, I.V. [Duke Free Electron Laser Laboratory (DFELL), Duke University, Durham, NC 27708 (United States); Ponomarev, V.Yu.; Savran, D. [Institut fuer Kernphysik, Technische Universitaet Darmstadt, 64289 Darmstadt (Germany); Tonchev, A.P.; Tornow, W.; Weller, H.R. [Triangle Universities Nuclear Laboratory (TUNL), Duke University, Durham, NC 27708 (United States); Werner, V. [A.W. Wright Nuclear Structure Laboratory (WNSL), Yale University, New Haven, CT (United States); Wu, Y.K. [Duke Free Electron Laser Laboratory (DFELL), Duke University, Durham, NC 27708 (United States); Zilges, A. [Institut fuer Kernphysik, Universitaet zu Koeln, 50937 Koeln (Germany)

2009-10-26

The Pb(gamma{sup -}>,gamma{sup '}) photon scattering reaction has been studied with the nearly monochromatic, linearly polarized photon beams at the High Intensity gamma-ray Source (HIgammaS) at the DFELL. Azimuthal scattering intensity asymmetries measured with respect to the polarization plane of the beam have been used for the first time to assign both the spin and parity quantum numbers of dipole excited states of {sup 206,207,208}Pb at excitation energies in the vicinity of 5.5 MeV. Evidence for dominant particle-core coupling is deduced from these results along with information on excitation energies and electromagnetic transition matrix elements. Implications of the existence of weakly coupled states built on highly excited core states in competition with 1homega single particle (hole) excitations at comparable energies are discussed.

Mode specific dynamics of the H2 + CH3 → H + CH4 reaction studied using quasi-classical trajectory and eight-dimensional quantum dynamics methods

International Nuclear Information System (INIS)

Wang, Yan; Li, Jun; Guo, Hua; Chen, Liuyang; Yang, Minghui; Lu, Yunpeng

2015-01-01

An eight-dimensional quantum dynamical model is proposed and applied to the title reaction. The reaction probabilities and integral cross sections have been determined for both the ground and excited vibrational states of the two reactants. The results indicate that the H 2 stretching and CH 3 umbrella modes, along with the translational energy, strongly promote the reactivity, while the CH 3 symmetric stretching mode has a negligible effect. The observed mode specificity is confirmed by full-dimensional quasi-classical trajectory calculations. The mode specificity can be interpreted by the recently proposed sudden vector projection model, which attributes the enhancement effects of the reactant modes to their strong couplings with the reaction coordinate at the transition state

Ultrafast excited state relaxation in long-chain polyenes

International Nuclear Information System (INIS)

Antognazza, Maria Rosa; Lueer, Larry; Polli, Dario; Christensen, Ronald L.; Schrock, Richard R.; Lanzani, Guglielmo; Cerullo, Giulio

2010-01-01

Graphical abstract: Excited state dynamics of a long-chain polyene studied by femtosecond pump-probe spectroscopy. - Abstract: We present a comprehensive study, by femtosecond pump-probe spectroscopy, of excited state dynamics in a polyene that approaches the infinite chain limit. By excitation with sub-10-fs pulses resonant with the 0-0 S 0 → S 2 transition, we observe rapid loss of stimulated emission from the bright excited state S 2 , followed by population of the hot S 1 state within 150 fs. Vibrational cooling of S 1 takes place within 500 fs and is followed by decay back to S 0 with 1 ps time constant. By excitation with excess vibrational energy we also observe the ultrafast formation of a long-living absorption, that is assigned to the triplet state generated by singlet fission.

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

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

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...

Excitation mechanisms of Er optical centers in GaN epilayers

International Nuclear Information System (INIS)

George, D. K.; Hawkins, M. D.; McLaren, M.; Vinh, N. Q.; Jiang, H. X.; Lin, J. Y.; Zavada, J. M.

2015-01-01

We report direct evidence of two mechanisms responsible for the excitation of optically active Er 3+ ions in GaN epilayers grown by metal-organic chemical vapor deposition. These mechanisms, resonant excitation via the higher-lying inner 4f shell transitions and band-to-band excitation of the semiconductor host, lead to narrow emission lines from isolated and the defect-related Er optical centers. However, these centers have different photoluminescence spectra, local defect environments, decay dynamics, and excitation cross sections. The photoluminescence at 1.54 μm from the isolated Er optical center which can be excited by either mechanism has the same decay dynamics, but possesses a much higher excitation cross-section under band-to-band excitation. In contrast, the photoluminescence at 1.54 μm from the defect-related Er optical center can only be observed through band-to-band excitation but has the largest excitation cross-section. These results explain the difficulty in achieving gain in Er doped GaN and indicate approaches for realization of optical amplification, and possibly lasing, at room temperature

Pure-Phase Selective Excitation in Fast-Relaxing Systems

Science.gov (United States)

Zangger, Klaus; Oberer, Monika; Sterk, Heinz

2001-09-01

Selective pulses have been used frequently for small molecules. However, their application to proteins and other macromolecules has been limited. The long duration of shaped-selective pulses and the short T2 relaxation times in proteins often prohibited the use of highly selective pulses especially on larger biomolecules. A very selective excitation can be obtained within a short time by using the selective excitation sequence presented in this paper. Instead of using a shaped low-intensity radiofrequency pulse, a cluster of hard 90° pulses, delays of free precession, and pulsed field gradients can be used to selectively excite a narrow chemical shift range within a relatively short time. Thereby, off-resonance magnetization, which is allowed to evolve freely during the free precession intervals, is destroyed by the gradient pulses. Off-resonance excitation artifacts can be removed by random variation of the interpulse delays. This leads to an excitation profile with selectivity as well as phase and relaxation behavior superior to that of commonly used shaped-selective pulses. Since the evolution of scalar coupling is inherently suppressed during the double-selective excitation of two different scalar-coupled nuclei, the presented pulse cluster is especially suited for simultaneous highly selective excitation of N-H and C-H fragments. Experimental examples are demonstrated on hen egg white lysozyme (14 kD) and the bacterial antidote ParD (19 kD).

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.

A benchmark study of electronic excitation energies, transition moments, and excited-state energy gradients on the nicotine molecule

Energy Technology Data Exchange (ETDEWEB)

Egidi, Franco, E-mail: franco.egidi@sns.it; Segado, Mireia; Barone, Vincenzo, E-mail: vincenzo.barone@sns.it [Scuola Normale Superiore, Piazza dei Cavalieri, 7 I-56126 Pisa (Italy); Koch, Henrik [Department of Chemistry, Norwegian University of Science and Technology, 7491 Trondheim (Norway); Cappelli, Chiara [Dipartimento di Chimica e Chimica Industriale, Università di Pisa, via G. Moruzzi, 3 I-56124 Pisa (Italy)

2014-12-14

In this work, we report a comparative study of computed excitation energies, oscillator strengths, and excited-state energy gradients of (S)-nicotine, chosen as a test case, using multireference methods, coupled cluster singles and doubles, and methods based on time-dependent density functional theory. This system was chosen because its apparent simplicity hides a complex electronic structure, as several different types of valence excitations are possible, including n-π{sup *}, π-π{sup *}, and charge-transfer states, and in order to simulate its spectrum it is necessary to describe all of them consistently well by the chosen method.

Nonlinear Dynamical Analysis for the Cable Excited with Parametric and Forced Excitation

Directory of Open Access Journals (Sweden)

C. Z. Qian

2014-01-01

Full Text Available Considering the deck vibration effect on the cable in cable-stayed bridge, using nonlinear structure dynamics theory, the nonlinear dynamical equation for the stayed cable excited with deck vibration is proposed. Research shows that the vertical vibration of the deck has a combined parametric and forced excitation effect on the cable when the angle of the cable is taken into consideration. Using multiscale method, the 1/2 principle parametric resonance is studied and the bifurcation equation is obtained. Despite the parameters analysis, the bifurcation characters of the dynamical system are studied. At last, by means of numerical method and software MATHMATIC, the effect rules of system parameters to the dynamical behavior of the system are studied, and some useful conclusions are obtained.

Vibratory synchronization transmission of a cylindrical roller in a vibrating mechanical system excited by two exciters

Science.gov (United States)

Zhang, Xueliang; Wen, Bangchun; Zhao, Chunyu

2017-11-01

In present work vibratory synchronization transmission (VST) of a cylindrical roller with dry friction in a vibrating mechanical system excited by two exciters, is studied. Using the average method, the criterion of implementing synchronization of two exciters and that of ensuring VST of a roller, are achieved. The criterion of stability of the synchronous states satisfies the Routh-Hurwitz principle. The influences of the structural parameters of the system to synchronization and stability, are discussed numerically, which can be served as the theoretical foundation for engineering designs. An experiment is carried out, which approximately verify the validity of the theoretical and numerical results, as well as the feasibility of the method used. Utilizing the VST theory of a roller, some types of vibrating crushing or grinding equipments, etc., can be designed.

Excited delirium: Consideration of selected medical and psychiatric issues

Directory of Open Access Journals (Sweden)

Edith Samuel

2009-01-01

Full Text Available Edith Samuel1, Robert B Williams1, Richard B Ferrell21Department of Psychology, Atlantic Baptist University, Moncton, New Brunswick Canada; 2Department of Psychiatry, Dartmouth Medical School, Lebanon, New Hampshire, USAAbstract: Excited delirium, sometimes referred to as agitated or excited delirium, is the label assigned to the state of acute behavioral disinhibition manifested in a cluster of behaviors that may include bizarreness, aggressiveness, agitation, ranting, hyperactivity, paranoia, panic, violence, public disturbance, surprising physical strength, profuse sweating due to hyperthermia, respiratory arrest, and death. Excited delirium is reported to result from substance intoxication, psychiatric illness, alcohol withdrawal, head trauma, or a combination of these. This communication reviews the history of the origins of excited delirium, selected research related to its causes, symptoms, management, and the links noted between it and selected medical and psychiatric conditions. Excited delirium involves behavioral and physical symptoms that are also observed in medical and psychiatric conditions such as rhabdomyolysis, neuroleptic malignant syndrome, and catatonia. A useful contribution of this communication is that it links the state of excited delirium to conditions for which there are known and effective medical and psychiatric interventions.Keywords: excited delirium, excited states, cocaine misuse, restraint or in custody deaths

Electron-impact excitation autoionization of Ga II

International Nuclear Information System (INIS)

Pindzola, M.S.; Griffin, D.C.; Bottcher, C.

1982-01-01

The general-reaction theory of Feshbach is applied, within the framework of the distorted-wave approximation, to the calculation of excitation-autoionization resonances in the electron-impact ionization of Ga + . Although the spectrum of autoionizing levels for Ga + is quite complex, we focus our attention on the important 3d 10 4s 2 → 3d 9 4s 2 4p inner-shell excitations. For excitation of the 3d 9 4s 2 4p 1 P 1 autoionizing level we make a general-reaction-theory calculation for the dominant partial-wave cross section and compute a typical resonance profile in the ejected-electron differential cross section. We find that the quantum-mechanical interference between the direct and indirect processes has a small effect on the total ionization cross section. Employing an independent-processes approximation we calculate excitation-autoionization contributions to all twelve levels of the 3d 9 4s 2 4p configuration. Using the results of our calculations and their comparison with a recent crossed-beam experiment by Rogers et al., we discuss the accuracy of the distorted-wave method and the effects of configuration interaction on energy levels and excitation cross sections

Systematics in Rydberg state excitations for ion-atom collisions

International Nuclear Information System (INIS)

Andresen, B.; Jensen, K.; Petersen, N.B.; Veje, E.

1976-01-01

Rydberg state excitations in the Ne + , Mg + -He collisions have been studied in the projectile energy range 10-75 keV by means of optical spectrometry in a search for systematic trends. The relative excitation cross sections for levels of a Rydberg term series are found to follow a general (nsup(x))sup(P) behaviour with P < approximately -3 varying with collision energy and particles, regardless of whether the excited state population results from direct excitation, single electron transfer, or double electron transfer. At higher collision energies P is approximately -3 as predicted by theory. Polarization of the emitted line radiation indicates that there is no general rule for the relative excitation of the different magnetic substates of the same level. A statistical distribution of excitation is found for levels within the same term when the fine structure splitting is small. (Auth.)

Radiation damage in nonmetallic solids under dense electronic excitation

International Nuclear Information System (INIS)

Itoh, Noriaki; Tanimura, Katsumi; Nakai, Yasuo

1992-01-01

Basic processes of radiation damage of insulators by dense electronic excitation are reviewed. First it is pointed out that electronic excitation of nonmetallic solids produces the self-trapped excitons and defect-related metastable states having relatively long lifetimes, and that the excitation of these metastable states, produces stable defects. The effects of irradiation with heavy ions, including track registration, are surveyed on the basis of the microscopic studies. It is pointed out also that the excitation of the metastable states plays a role in laser-induced damage at relatively low fluences, while the laser damage has been reported to be governed by heating of free electrons produced by multiphoton excitation. Difference in the contributions of the excitation of metastable defects to laser-induced damage of surfaces, or laser ablation, and laser-induced bulk damage is stressed. (orig.)

Dynamics of Microbeams under Multi-Frequency Excitations

KAUST Repository

Ibrahim, Alwathiqbellah

2017-01-24

This paper presents an investigation of the dynamics of microbeams under multiple harmonic electrostatic excitation frequencies. First, the response of a cantilever microbeam to two alternating current (AC) source excitation is examined. We show by simulations the response of the microbeam at primary resonance (near the fundamental natural frequency) and at secondary resonances (near half, superharmonic, and twice, subharmonic, the fundamental natural frequency). A multimode Galerkin method combined with the Euler-Bernoulli beam equation, accounting for the nonlinear electrostatic force, has been used to develop a reduced order model. The response of the cantilever microbeam to three AC source excitation is also investigated and shown as a promising technique to enhance the bandwidth of resonators. Finally, an experimental study of a clamped-clamped microbeam is conducted, demonstrating the multi-frequency excitation resonances using two, three, and four AC sources.

Dynamics of Microbeams under Multi-Frequency Excitations

KAUST Repository

Ibrahim, Alwathiqbellah; Jaber, Nizar; Chandran, Akhil; Thirupathi, Maloth; Younis, Mohammad I.

2017-01-01

This paper presents an investigation of the dynamics of microbeams under multiple harmonic electrostatic excitation frequencies. First, the response of a cantilever microbeam to two alternating current (AC) source excitation is examined. We show by simulations the response of the microbeam at primary resonance (near the fundamental natural frequency) and at secondary resonances (near half, superharmonic, and twice, subharmonic, the fundamental natural frequency). A multimode Galerkin method combined with the Euler-Bernoulli beam equation, accounting for the nonlinear electrostatic force, has been used to develop a reduced order model. The response of the cantilever microbeam to three AC source excitation is also investigated and shown as a promising technique to enhance the bandwidth of resonators. Finally, an experimental study of a clamped-clamped microbeam is conducted, demonstrating the multi-frequency excitation resonances using two, three, and four AC sources.

Excited State Spectra and Dynamics of Phenyl-Substituted Butadienes

DEFF Research Database (Denmark)

Wallace-Williams, Stacie E.; Schwartz, Benjamin J.; Møller, Søren

1994-01-01

indicate that phenyl torsional motion is not important to the excited-state dynamics and reveal alternative excited-state reaction pathways. The results demonstrate how molecular systems that are structually similar can exhibit different electronic properties and excited-state dynamics....

Efficient channel-plasmon excitation by nano-mirrors

DEFF Research Database (Denmark)

Radko, Ilya P.; Stær, Tobias Holmgaard; Han, Zhanghua

2011-01-01

We demonstrate a configuration for efficient channel-plasmon mode excitation using tapered terminations of V-shaped groove waveguides. The plasmon excitation is achieved by directly illuminating tapers of gold V-grooves with a focused laser beam, incident normally onto the sample surface. For near......-infrared wavelengths, we find experimentally as well as numerically, by conducting three-dimensional finite-difference time-domain calculations, that the efficiency of channel-plasmon mode excitation exceeds 10% in the optimum configuration, which is the highest experimentally observed efficiency of coupling from free-propagation...

Scanless two-photon excitation of channelrhodopsin-2

DEFF Research Database (Denmark)

Papagiakoumou, E.; Anselmi, F.; Bègue, A.

2010-01-01

developed a method that combines generalized phase contrast with temporal focusing (TF-GPC) to shape two-photon excitation for this purpose. The illumination patterns are generated automatically from fluorescence images of neurons and shaped to cover the cell body or dendrites, or distributed groups...... of cells. The TF-GPC two-photon excitation patterns generated large photocurrents in Channelrhodopsin-2–expressing cultured cells and neurons and in mouse acute cortical slices. The amplitudes of the photocurrents can be precisely modulated by controlling the size and shape of the excitation volume and...

Method of producing excited states of atomic nuclei

International Nuclear Information System (INIS)

Morita, M.; Morita, R.

1976-01-01

A method is claimed of producing excited states of atomic nuclei which comprises bombarding atoms with x rays or electrons, characterized in that (1) in the atoms selected to be produced in the excited state of their nuclei, (a) the difference between the nuclear excitation energy and the difference between the binding energies of adequately selected two electron orbits is small enough to introduce the nuclear excitation by electron transition, and (b) the system of the nucleus and the electrons in the case of ionizing an orbital electron in said atoms should satisfy the spin and parity conservation laws; and (2) the energy of the bombarding x rays or electrons should be larger than the binding energy of one of the said two electron orbits which is located at shorter distance from the atomic nucleus. According to the present invention, atomic nuclei can be excited in a relatively simple manner without requiring the use of large scale apparatus, equipment and production facilities, e.g., factories. It is also possible to produce radioactive substances or separate a particular isotope with an extremely high purity from a mixture of isotopes by utilizing nuclear excitation

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.

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

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)

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

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

Feasibility study of internal conversion electron spectroscopy of {sup 229m}Th

Energy Technology Data Exchange (ETDEWEB)

Seiferle, Benedict; Wense, Lars von der; Thirolf, Peter G. [Ludwig-Maximilians-Universitaet Muenchen, Garching (Germany)

2017-05-15

With an expected energy of 7.8(5) eV, the isomeric first excited state in {sup 229}Th exhibits the lowest excitation energy of all known nuclei. Until today, a value for the excitation energy has been inferred only by indirect measurements. In this paper we propose an experimental method that is potentially capable of measuring the ground-state transition energy via the detection of the internal conversion electrons. MatLab-based Monte Carlo simulations have been performed to obtain an estimate of the expected statistics and to test the feasibility and the expected precision of the experiment. From the simulations we conclude that with the presented methods an energy determination with a precision of better than 0.1 eV is within reach. (orig.)

Broadband transient absorption spectroscopy with 1- and 2-photon excitations: Relaxation paths and cross sections of a triphenylamine dye in solution

Energy Technology Data Exchange (ETDEWEB)

Moreno, J.; Dobryakov, A. L.; Hecht, S., E-mail: sh@chemie.hu-berlin.de, E-mail: skovale@chemie.hu-berlin.de; Kovalenko, S. A., E-mail: sh@chemie.hu-berlin.de, E-mail: skovale@chemie.hu-berlin.de [Department of Chemistry, Humboldt-Universität zu Berlin, Brook-Taylor-St. 2, 12489 Berlin (Germany); Ioffe, I. N. [Department of Chemistry, Lomonosov Moscow State University, 119991 Moscow (Russian Federation); Granovsky, A. A. [Firefly Project, 117593 Moscow (Russian Federation)

2015-07-14

1-photon (382 nm) and 2-photon (752 nm) excitations to the S{sub 1} state are applied to record and compare transient absorption spectra of a push-pull triphenylamine (TrP) dye in solution. After 1-photon excitation, ultrafast vibrational and structural molecular relaxations are detected on a 0.1 ps time scale in nonpolar hexane, while in polar acetonitrile, the spectral evolution is dominated by dipolar solvation. Upon 2-photon excitation, transient spectra in hexane reveal an unexpected growth of stimulated emission (SE) and excited-state absorption (ESA) bands. The behavior is explained by strong population transfer S{sub 1} → S{sub n} due to resonant absorption of a third pump photon. Subsequent S{sub n} → S{sub 1} internal conversion (with τ{sub 1} = 1 ps) prepares a very hot S{sub 1} state which cools down with τ{sub 2} = 13 ps. The pump pulse energy dependence proves the 2-photon origin of the bleach signal. At the same time, SE and ESA are strongly affected by higher-order pump absorptions that should be taken into account in nonlinear fluorescence applications. The 2-photon excitation cross sections σ{sup (2)} = 32 ⋅ 10{sup −50} cm{sup 4} s at 752 nm are evaluated from the bleach signal.

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.

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.

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

Theoretical resonant electron-impact vibrational excitation, dissociative recombination and dissociative excitation cross sections of ro-vibrationally excited BeH"+ ion

International Nuclear Information System (INIS)

Laporta, V.; Chakrabarti, K.; Celiberto, R.; Janev, R. K.; Mezei, J. Zs.; Niyonzima, S.; Tennyson, J.; Schneider, I.F.

2017-01-01

A theoretical study of resonant vibrational excitation, dissociative recombination and dissociative excitation processes of the beryllium monohydride cation, BeH"+ , induced by electron impact, is reported. Full sets of ro-vibrationally-resolved cross sections and of the corresponding Maxwellian rate coefficients are presented for the three processes. Particular emphasis is given to the high-energy behaviour. Potential curves of "2σ"+, "2σ and "2δ symmetries and the corresponding resonance widths, obtained from R-matrix calculations, provide the input for calculations which use a local complex-potential model for resonant collisions in each of the three symmetries. Rotational motion of nuclei and isotopic effects are also discussed. The relevant results are compared with those obtained using a multichannel quantum defect theory method. Full results are available from the Phys4Entry database.

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).

Wideband excitation in nonlinear vibro-acoustic modulation for damage detection

Science.gov (United States)

Klepka, A.; Adamczyk, M.; Pieczonka, L.; Staszewski, W. J.

2016-04-01

The paper discusses the use of wideband excitation in nonlinear vibro-acoustic modulation technique (VAM) used for damage detection. In its original form, two mono-harmonic signals (low and high frequency) are used for excitation. The low frequency excitation is typically selected based on a modal analysis test and high frequency excitation is selected arbitrarily in the ultrasonic frequency range. This paper presents a different approach with use of wideband excitation signals. The proposed approach gives the possibility to simplify the testing procedure by omitting the modal test used to determine the value of low frequency excitation. Simultaneous use of wideband excitation for high frequency solves the ambiguity related to the selection of the frequency of acoustic wave. Broadband excitation signals require, however, more elaborate signal processing methods to determine the intensity of modulation for a given bandwidth. The paper discusses the proposed approach and the related signal processing procedure. Experimental validation of the proposed technique is performed on a laminated composite plate with a barely visible impact damage that was generated in an impact test. Piezoceramic actuators are used for vibration excitation and a scanning laser vibrometer is used for noncontact data acquisition.

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.)

Search for excited charged leptons in electron positron collisions

CERN Document Server

Vachon, Brigitte Marie Christine; Sobie, Randall

2002-01-01

A search for evidence that fundamental particles are made of smaller subconstituents is performed. The existence of excited states of fundamental particles would be an unambiguous indication of their composite nature. Experimental signatures compatible with the production of excited states of charged leptons in electron-positron collisions are studied. The data analysed were collected by the OPAL detector at the LEP collider. No evidence for the existence of excited states of charged leptons was found. Upper limits on the product of the cross-section and the electromagnetic branching fraction are inferred. Using results from the search for singly produced excited leptons, upper limits on the ratio of the excited lepton coupling constant to the compositeness scale are calculated. From pair production searches, 95% confidence level lower limits on the masses of excited electrons, muons and taus are determined to be 103.2 GeV.

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

Ion-Beam-Excited Electrostatic Ion Cyclotron Instability

DEFF Research Database (Denmark)

Michelsen, Poul; Pécseli, Hans; Juul Rasmussen, Jens

1977-01-01

The stability limits of the ion‐beam‐excited, electrostatic, ion cyclotron instability were investigated in a Q‐machine plasma where the electrons could be heated by microwaves. In agreement with theory, the beam energy necessary for excitation decreased with increasing electron temperature....

Ion-Beam-Excited, Electrostatic, Ion Cyclotron Instability

DEFF Research Database (Denmark)

Michelsen, Poul; Pécseli, Hans; Juul Rasmussen, Jens

1977-01-01

The stability limits of the ion‐beam‐excited, electrostatic, ion cyclotron instability were investigated in a Q‐machine plasma where the electrons could be heated by microwaves. In agreement with theory, the beam energy necessary for excitation decreased with increasing electron temperature....

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

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.

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.

Photoluminescence excitation spectroscopy of SiV- and GeV- color center in diamond

Science.gov (United States)

Häußler, Stefan; Thiering, Gergő; Dietrich, Andreas; Waasem, Niklas; Teraji, Tokuyuki; Isoya, Junichi; Iwasaki, Takayuki; Hatano, Mutsuko; Jelezko, Fedor; Gali, Adam; Kubanek, Alexander

2017-06-01

Color centers in diamond are important quantum emitters for a broad range of applications ranging from quantum sensing to quantum optics. Understanding the internal energy level structure is of fundamental importance for future applications. We experimentally investigate the level structure of an ensemble of few negatively charged silicon-vacancy (SiV-) and germanium-vacancy (GeV-) centers in bulk diamond at room temperature by photoluminescence (PL) and excitation (PLE) spectroscopy over a broad wavelength range from 460 to 650 {nm} and perform power-dependent saturation measurements. For SiV- our experimental results confirm the presence of a higher energy transition at ˜ 2.31 {eV}. By comparison with detailed theoretical simulations of the imaginary dielectric function we interpret the transition as a dipole-allowed transition from {}2{E}g-state to {}2{A}2u-state where the corresponding a 2u -level lies deeply inside the diamond valence band. Therefore, the transition is broadened by the diamond band. At higher excitation power of 10 {mW} we indicate signs of a parity-conserving transition at ˜ 2.03 {eV} supported by saturation measurements. For GeV- we demonstrate that the PLE spectrum is in good agreement with the mirror image of the PL spectrum of the zero-phonon line. Experimentally we do not observe a higher lying energy level up to a transition wavelength of 460 {nm}. The observed PL spectra are identical, independent of excitation wavelength, suggesting a rapid decay to {}2{E}u excited state and followed by optical transition to {}2{E}g ground state. Our investigations convey important insights for future quantum optics and quantum sensing experiments based on SiV--center and GeV--center in diamond.

Nonlinear Forced Vibration of a Viscoelastic Buckled Beam with 2 : 1 Internal Resonance

Directory of Open Access Journals (Sweden)

Liu-Yang Xiong

2014-01-01

Full Text Available Nonlinear dynamics of a viscoelastic buckled beam subjected to primary resonance in the presence of internal resonance is investigated for the first time. For appropriate choice of system parameters, the natural frequency of the second mode is approximately twice that of the first providing the condition for 2 : 1 internal resonance. The ordinary differential equations of the two mode shapes are established using the Galerkin method. The problem is replaced by two coupled second-order differential equations with quadratic and cubic nonlinearities. The multiple scales method is applied to derive the modulation-phase equations. Steady-state solutions of the system as well as their stability are examined. The frequency-amplitude curves exhibit the steady-state response in the directly excited and indirectly excited modes due to modal interaction. The double-jump, the saturation phenomenon, and the nonperiodic region phenomena are observed illustrating the influence of internal resonance. The validity range of the analytical approximations is assessed by comparing the analytical approximate results with a numerical solution by the Runge-Kutta method. The unstable regions in the internal resonance are explored via numerical simulations.

General active space commutator-based coupled cluster theory of general excitation rank for electronically excited states: implementation and application to ScH.

Science.gov (United States)

Hubert, Mickaël; Olsen, Jeppe; Loras, Jessica; Fleig, Timo

2013-11-21

We present a new implementation of general excitation rank coupled cluster theory for electronically excited states based on the single-reference multi-reference formalism. The method may include active-space selected and/or general higher excitations by means of the general active space concept. It may employ molecular integrals over the four-component Lévy-Leblond Hamiltonian or the relativistic spin-orbit-free four-component Hamiltonian of Dyall. In an initial application to ground- and excited states of the scandium monohydride molecule we report spectroscopic constants using basis sets of up to quadruple-zeta quality and up to full iterative triple excitations in the cluster operators. Effects due to spin-orbit interaction are evaluated using two-component multi-reference configuration interaction for assessing the accuracy of the coupled cluster results.

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

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

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.

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

Excited state kinetics of anthracene-bridge-aniline intramolecular exciplexes

DEFF Research Database (Denmark)

Thyrhaug, Erling; Hammershøj, Peter; Kjær, Kasper Skov

2014-01-01

excited anthracene state (LE) and an excited state complex (exciplex, EP) in non-polar solvents. The kinetics of the excited state processes were established in decalin from the time-resolved emission, and was shown to be strongly influenced by an electron-transfer state (ET). For quantitative studies...

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

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.

Efficient channel-plasmon excitation by nano-mirrors

DEFF Research Database (Denmark)

Radko, Ilya; Holmgaard Stær, Tobias; Han, Zhanghua

2011-01-01

We demonstrate a configuration for efficient channel-plasmon mode excitation using tapered terminations of V-shaped groove waveguides. The plasmon excitation is achieved by directly illuminating tapers of gold V-grooves with a focused laser beam, incident normally onto the sample surface. For nea...

Elastic wave excitation in centrosymmetric strontium titanate crystals

International Nuclear Information System (INIS)

Yushin, N.K.; Sotnikov, A.V.

1980-01-01

The main experimental dependencies are measured and the excitation mechanism of elastic waves in centrosymmetric crystals is established. The surface generation of three-dimensional elastic waves of the 30 MHz frequency in strontium titanate crystals is observed and studied. Elastic wave excitation is observed in the 4 350 K temperature range. The efficiency of hysteresis excitation depends on the external electric field. The effect of light irradiation on the amplitude of excited elastic waves is observed. It is shown that escitation is connected with linearization of electrostriction by the constant electric field appearing in a near-surface crystal layer due to phenomena in the Schottky barrier and appearance of electretic near-electrode layers

Searches for excited fermions in ep collisions at HERA

International Nuclear Information System (INIS)

Chekanov, S.; Derrick, M.; Krakauer, D.

2002-01-01

Searches in ep collisions for heavy excited fermions have been performed with the ZEUS detector at HERA. Excited states of electrons and quarks have been searched for in e + p collisions at a centre-of-mass energy of 300 GeV using an integrated luminosity of 47.7 pb -1 . Excited electrons have been sought via the decays e*→eγ, e*→eZ and e*→νW. Excited quarks have been sought via the decays q*→qγ and q*→qW. A search for excited neutrinos decaying via ν*→νγ, ν*→νZ and ν*→eW is presented using e - p collisions at 318 GeV centre-of-mass energy, corresponding to an integrated luminosity of 16.7 pb -1 . No evidence for any excited fermion is found, and limits on the characteristic couplings are derived for masses ≤250 GeV

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.

Luminescence from ZnSe excited by picosecond mid-infrared FEL pulses

International Nuclear Information System (INIS)

Mitsuyu, T.; Suzuki, T.; Tomimasu, T.

1998-01-01

We have observed blue band-edge emission from a ZnSe crystal under irradiation of mid-infrared picosecond free electron laser (FEL) pulses. The emission characteristics including spectrum, excitation power dependence, excitation wavelength dependence, and decay time have been investigated. The experimental results have indicated that it is difficult to understand the excitation process by multiphoton excitation, thermal excitation, or excitation through mid-gap levels. (Copyright (c) 1998 Elsevier Science B.V., Amsterdam. All rights reserved.)

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.

New excitation equipment for 220 MW generators in Kozloduy NPP

International Nuclear Information System (INIS)

Tomerlin, D.

2001-01-01

Rehabilitation on the excitation equipment for Generator 5, Reactor Unit 3, in Kozloduy NPP was completed in November 2000. ABB's Static Excitation System based on UNITROL 5000 technology has been chosen by the Bulgarian National Utility and Kozloduy NPP to substitute the original Russian excitation system equipment with electro-magnetic voltage regulators. The substitution is in a rehabilitation package of four excitation system equipment for Generator 5 and 6 of Reactor Unit 3 and Generator 7 and 8 of Reactor Unit 4 after a short overview of the original excitation system this paper describes the new Static Excitation System UNITROL 5000 including configuration with block diagram, its main features and merits such as modes of operation, limiter, special control functions and diagnostic facilities. Furthermore, new facilities, which are implemented in UNITROL 5000, such as dynamic current distribution among the thyristors working in parallel as well as the start-up from the residual magnetism are mentioned. Special functions including a so-called free-running mode of operation and automatic change over sequence from new excitation system to the stand-by excitation system, which is DC exciter machine, are described. Some records of the transient responses performed during the commissioning and a photograph of a manufactured system are provided. (author)

Entanglement entropy for (3+1)-dimensional topological order with excitations

Science.gov (United States)

Wen, Xueda; He, Huan; Tiwari, Apoorv; Zheng, Yunqin; Ye, Peng

2018-02-01

Excitations in (3+1)-dimensional [(3+1)D] topologically ordered phases have very rich structures. (3+1)D topological phases support both pointlike and stringlike excitations, and in particular the loop (closed string) excitations may admit knotted and linked structures. In this work, we ask the following question: How do different types of topological excitations contribute to the entanglement entropy or, alternatively, can we use the entanglement entropy to detect the structure of excitations, and further obtain the information of the underlying topological order? We are mainly interested in (3+1)D topological order that can be realized in Dijkgraaf-Witten (DW) gauge theories, which are labeled by a finite group G and its group 4-cocycle ω ∈H4[G ;U(1 ) ] up to group automorphisms. We find that each topological excitation contributes a universal constant lndi to the entanglement entropy, where di is the quantum dimension that depends on both the structure of the excitation and the data (G ,ω ) . The entanglement entropy of the excitations of the linked/unlinked topology can capture different information of the DW theory (G ,ω ) . In particular, the entanglement entropy introduced by Hopf-link loop excitations can distinguish certain group 4-cocycles ω from the others.

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...

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

Switchable directional excitation surface plasmon polaritons with dielectric nanoantennas

DEFF Research Database (Denmark)

Sinev, I.; Komissarenko, F.; Bogdanov, A.

We demonstrate directional launching of surface plasmon polaritons on thin goldfilm with a single silicon nanosphere. The directivity pattern of the excited surface waves exhibits rapid switching from forward to backward excitation, which is driven by the mutual interference of magnetic and elect......We demonstrate directional launching of surface plasmon polaritons on thin goldfilm with a single silicon nanosphere. The directivity pattern of the excited surface waves exhibits rapid switching from forward to backward excitation, which is driven by the mutual interference of magnetic...

Crossed-coil detection of two-photon excited nuclear quadrupole resonance

Science.gov (United States)

Eles, Philip T.; Michal, Carl A.

2005-08-01

Applying a recently developed theoretical framework for determining two-photon excitation Hamiltonians using average Hamiltonian theory, we calculate the excitation produced by half-resonant irradiation of the pure quadrupole resonance of a spin-3/2 system. This formalism provides expressions for the single-quantum and double-quantum nutation frequencies as well as the Bloch-Siegert shift. The dependence of the excitation strength on RF field orientation and the appearance of the free-induction signal along an axis perpendicular to the excitation field provide an unmistakable signature of two-photon excitation. We demonstrate single- and double-quantum excitation in an axially symmetric system using 35Cl in a single crystal of potassium chlorate ( ωQ = 28 MHz) with crossed-coil detection. A rotation plot verifies the orientation dependence of the two-photon excitation, and double-quantum coherences are observed directly with the application of a static external magnetic field.

Excitation and recombination of donor-acceptor pairs in ZnTe

International Nuclear Information System (INIS)

Nakashima, S.; Yasuda, S.

1979-01-01

The photoluminescence spectra and its excitation spectra of the donor-acceptor pairs are observed in ZnTe crystals doped with Li and As in the region below the bandgap energy. The relaxation of electrons and holes into the first excited state of d-a pairs is studied for the three excitation processes: (1) bound-to-bound transitions, (2) bound-to-free transitions, and (3) free-to-free transitions. It is concluded that most of the electrons and holes at the excited states of each impurity level are relaxed rapidly into their ground states before the occurrence of the recombination involving the excited states. For the excitation process (2), conduction electrons are preferentially trapped by positively charged pairs. The redistribution of bound holes by hopping is suggested to explain the broad d-a emission band observed for the bound-to-free excitation for very distant pairs. (author)

Vibrational excitation of D2 by low energy electrons

International Nuclear Information System (INIS)

Buckman, S.J.; Phelps, A.V.

1985-01-01

Excitation coefficients for the production of vibrationally exicted D 2 by low energy electrons have been determined from measurements of the intensity of infrared emission from mixtures of D 2 and small concentrations of CO 2 or CO. The measurements were made using the electron drift tube technique and covered electric field to gas density ratios (E/n) from (5 to 80) x 10 -21 V m 2 , corresponding to mean electron energies between 0.45 and 4.5 eV. The CO 2 and CO concentrations were chosen to allow efficient excitation transfer from the D 2 to the carbon containing molecule, but to minimize direct excitation of the CO 2 or CO. The measured infrared intensities were normalized to predicted values for N 2 --CO 2 and N 2 --CO mixtures at E/n where the efficiency of vibrational excitation is known to be very close to 100%. The experimental excitation coefficients are in satisfactory agreement with predictions based on electron--D 2 cross sections at mean electron energies below 1 eV, but are about 50% too high at mean energies above about 2 eV. Application of the technique to H 2 did not yield useful vibrational excitation coefficients. The effective coefficients in H 2 --CO 2 mixtures were a factor of about 3 times the predicted values. For our H 2 --CO mixtures the excitation of CO via excitation transfer from H 2 is small compared to direct electron excitation of CO molecules. Published experiments and theories on electron--H 2 and electron--D 2 collisions are reviewed to obtain the cross sections used in the predictions

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...

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.

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)

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

Versatile single-molecule multi-color excitation and detection fluorescence setup for studying biomolecular dynamics

KAUST Repository

Sobhy, M. A.

2011-11-07

Single-molecule fluorescence imaging is at the forefront of tools applied to study biomolecular dynamics both in vitro and in vivo. The ability of the single-molecule fluorescence microscope to conduct simultaneous multi-color excitation and detection is a key experimental feature that is under continuous development. In this paper, we describe in detail the design and the construction of a sophisticated and versatile multi-color excitation and emission fluorescence instrument for studying biomolecular dynamics at the single-molecule level. The setup is novel, economical and compact, where two inverted microscopes share a laser combiner module with six individual laser sources that extend from 400 to 640 nm. Nonetheless, each microscope can independently and in a flexible manner select the combinations, sequences, and intensities of the excitation wavelengths. This high flexibility is achieved by the replacement of conventional mechanical shutters with acousto-optic tunable filter (AOTF). The use of AOTF provides major advancement by controlling the intensities, duration, and selection of up to eight different wavelengths with microsecond alternation time in a transparent and easy manner for the end user. To our knowledge this is the first time AOTF is applied to wide-field total internal reflection fluorescence (TIRF) microscopy even though it has been commonly used in multi-wavelength confocal microscopy. The laser outputs from the combiner module are coupled to the microscopes by two sets of four single-mode optic fibers in order to allow for the optimization of the TIRF angle for each wavelength independently. The emission is split into two or four spectral channels to allow for the simultaneous detection of up to four different fluorophores of wide selection and using many possible excitation and photoactivation schemes. We demonstrate the performance of this new setup by conducting two-color alternating excitation single-molecule fluorescence resonance energy

Radiation from an excited vortex in the Abelian Higgs model

Science.gov (United States)

Arodź, H.; Hadasz, L.

1996-09-01

An excited vortex in the Abelian Higgs model is investigated with the help of a polynomial approximation. The excitation consists of the longitudinal component of a vector field trapped by the vortex. The energy and profile of the excitation as well as its back reaction on the vortex are found in the case of small κ. It turns out that the width of the excited vortex oscillates in time. Moreover, the vector field has a radiative long range component. Also, an upper bound on the amplitude of the excitation is found.

Rotational Spectrum of 1,1-Difluoroethane: Internal Rotation Analysis and Structure

Science.gov (United States)

Villamanan, R. M.; Chen, W. D.; Wlodarczak, G.; Demaison, J.; Lesarri, A. G.; Lopez, J. C.; Alonso, J. L.

1995-05-01

The rotational spectrum of CH3CHF2 in its ground state was measured up to 653 GHz. Accurate rotational and centrifugal distortion constants were determined. The internal rotation splittings were analyzed using the internal axis method. An ab initio structure has been calculated and a near-equilibrium structure has been estimated using offsets derived empirically. This structure was compared to an experimental r0 structure. The four lowest excited states (including the methyl torsion) have also been assigned.

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

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.

On the resonant coherent excitation of relativistic heavy ions

International Nuclear Information System (INIS)

Pivovarov, Y.L.; Geissel, H.; Filimonov, Yu.M.; Krivosheev, O.E.; Scheidenberger, C.

1995-07-01

New accelerator facilities open up an interesting new field of experiments on basic channeling as well as on atomic and nuclear resonant coherent exitation (RCE) of heavy ions penetrating through aligned crystals at relativistic energies. Results of computer simulations are presented to characterize the resonant coherent excitation of atomic levels of relativistic hydrogen-like heavy ions. Nuclear resonant coherent excitation reveals interesting different characteristics compared to the corresponding atomic excitation inside crystals. An important result of our model calculations is that poorly-channeled ions have a higher nuclear excitation probability than well-channeled ions. (orig.)

Effects of intermediate load on performance limitations in excitation control

Directory of Open Access Journals (Sweden)

Pichai Aree

2008-05-01

Full Text Available The stability of excitation control systems is of great concern in power system operations. In this paper, the effects of intermediate load on performance limitation in excitation control are studied. The results reveal that the open-loop characteristic of synchronous machine’s flux linkage can be changed from minimum to non-minimum phase at a high level of intermediate load. This change leads to instability of synchronous machines under manual excitation control. A particular emphasis is also given to investigate the fundamental limitations in excitation control, imposed by non-minimum phases with regard to the open-loop right-half-plane (ORHP pole. The study demonstrates the difficulties of excitation control tuning to achieve the desired performance and robustness under the ORHP pole occurrence. Moreover, this paper shows the conditional stability in excitation control loop, where either an increase or decrease of the exciter gain causes a destabilization of the system’s stability. Frequency response techniques are used for these investigations.

Dynamic performance estimation of stator voltage regulator in rotary exciter system with DC exciter

Directory of Open Access Journals (Sweden)

Stojić Đorđe

2011-01-01

Full Text Available In this paper, procedure for AVR parameter estimation is proposed, based on step responses when synchronous generator in idle run. The exciter system includes AVR, thyristor rectifier and DC exciter. AVR is realized in the form of cascade control structure with two control loops. PID controller in the outer loop represents the primary controller. P controller in the inner loop represents secondary controller which enables the faster field current response time. The aim of procedure is to determine equivalent gain of PID controller and thyristor rectifier. The measurements used in the parameter estimation procedure are taken from fossil power plant 'Kolubara A', aggregate A5.

Integrated light in direct excitation and energy transfer luminescence

OpenAIRE

Chimczak, Eugeniusz

2007-01-01

Integrated light in direct excitation and energy transfer luminescence has been investigated. In the investigations reported here, monomolecular centers were taken into account. It was found that the integrated light is equal to the product of generation rate and time of duration of excitation pulse for both direct excitation and energy transfer luminescence.

Propylparaben reduces the excitability of hippocampal neurons by blocking sodium channels.

Science.gov (United States)

Lara-Valderrábano, Leonardo; Rocha, Luisa; Galván, Emilio J

2016-12-01

Propylparaben (PPB) is an antimicrobial preservative widely used in food, cosmetics, and pharmaceutics. Virtual screening methodologies predicted anticonvulsant activity of PPB that was confirmed in vivo. Thus, we explored the effects of PPB on the excitability of hippocampal neurons by using standard patch clamp techniques. Bath perfusion of PPB reduced the fast-inactivating sodium current (I Na ) amplitude, causing a hyperpolarizing shift in the inactivation curve of the I Na, and markedly delayed the sodium channel recovery from the inactivation state. Also, PPB effectively suppressed the riluzole-sensitive, persistent sodium current (I NaP ). PPB perfusion also modified the action potential kinetics, and higher concentrations of PPB suppressed the spike activity. Nevertheless, the modulatory effects of PPB did not occur when PPB was internally applied by whole-cell dialysis. These results indicate that PPB reduces the excitability of CA1 pyramidal neurons by modulating voltage-dependent sodium channels. The mechanistic basis of this effect is a marked delay in the recovery from inactivation state of the voltage-sensitive sodium channels. Our results indicate that similar to local anesthetics and anticonvulsant drugs that act on sodium channels, PPB acts in a use-dependent manner. Copyright © 2016 Elsevier B.V. All rights reserved.

Investigation on method of estimating the excitation spectrum of vibration source

International Nuclear Information System (INIS)

Zhang Kun; Sun Lei; Lin Song

2010-01-01

In practical engineer area, it is hard to obtain the excitation spectrum of the auxiliary machines of nuclear reactor through direct measurement. To solve this problem, the general method of estimating the excitation spectrum of vibration source through indirect measurement is proposed. First, the dynamic transfer matrix between the virtual excitation points and the measure points is obtained through experiment. The matrix combined with the response spectrum at the measure points under practical work condition can be used to calculate the excitation spectrum acts on the virtual excitation points. Then a simplified method is proposed which is based on the assumption that the vibration machine can be regarded as rigid body. The method treats the centroid as the excitation point and the dynamic transfer matrix is derived by using the sub structure mobility synthesis method. Thus, the excitation spectrum can be obtained by the inverse of the transfer matrix combined with the response spectrum at the measure points. Based on the above method, a computing example is carried out to estimate the excitation spectrum acts on the centroid of a electrical pump. By comparing the input excitation and the estimated excitation, the reliability of this method is verified. (authors)

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

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.

Enhanced eumelanin emission by stepwise three-photon excitation

Science.gov (United States)

Kerimo, Josef; Rajadhyaksha, Milind; DiMarzio, Charles A.

2011-03-01

Eumelanin fluorescence from Sepia officinalis and black human hair was activated with near-infrared radiation and multiphoton excitation. A third order multiphoton absorption by a step-wise process appears to be the underlying mechanism. The activation was caused by a photochemical process since it could not be reproduced by simple heating. Both fluorescence and brightfield imaging indicate the near-infrared irradiation caused photodamage to the eumelanin and the activated emission originated from the photodamaged region. At least two different components with about thousand-fold enhanced fluorescence were activated and could be distinguished by their excitation properties. One component was excited with wavelengths in the visible region and exhibited linear absorption dependence. The second component could be excited with near-infrared wavelengths and had a third order dependence on the laser power. The third order dependence is explained by a step-wise excited state absorption (ESA) process since it could be observed equally with the CW and femtosecond lasers. The new method for photoactivating the eumelanin fluorescence was used to map the melanin content in human hair.

Coulomb excitation of $^{110}$Sn using REX-ISOLDE

CERN Document Server

Ekström, A; Hurst, A; Fahlander, C; Banu, A; Butler, P; Eberth, J; Górska, M; Habs, D; Huyse, M; Kester, O; Niedermayer, O; Nilsson, T; Pantea, M; Scheit, H; Schwalm, D; Sletten, G; Ushasi, D P; Van Duppen, P; Warr, N; Weisshaar, D

2006-01-01

In this paper, we report the preliminary result from the first Coulomb excitation experiment at REX-ISOLDE (Habs et al 1998 Nucl. Instrum. Methods B 139 128) using neutron-deficient Sn-beams. The motivation of the experiment is to deduce the reduced transition probability, B(E2 ; 2$^+\\rightarrow$ 0$^+$) , for the sequence of neutron deficient, unstable, even-even Sn-isotopes from using a radioactive beam opens up a new path to study the lifetime of the first excited 2$^+$ state in these isotopes. The de-excitation path following fusion-evaporation reactions will for the even-even Sn isotopes pass via an isomeric 6$^+$ state, located at higher energy, which thus hampers measurements of the lifetime of the first excited state using, e.g., recoil-distance methods. For this reason the reduced transition probability of the first excited 2$^+$ state has remained unknown in this chain of isotopes although the B(E2) value of the stable isotope $^{112}$Sn was measured approximately 30 years ago (see, e.g., Stelson et...

Characterizing Plasmonic Excitations of Quasi-2D Chains

Science.gov (United States)

Townsend, Emily; Bryant, Garnett

A quantum description of the optical response of nanostructures and other atomic-scale systems is desirable for modeling systems that use plasmons for quantum information transfer, or coherent transport and interference of quantum states, as well as systems small enough for electron tunneling or quantum confinement to affect the electronic states of the system. Such a quantum description is complicated by the fact that collective and single-particle excitations can have similar energies and thus will mix. We seek to better understand the excitations of nanosystems to identify which characteristics of the excitations are most relevant to modeling their behavior. In this work we use a quasi 2-dimensional linear atomic chain as a model system, and exact diagonalization of the many-body Hamiltonian to obtain its excitations. We compare this to previous work in 1-d chains which used a combination of criteria involving a many-body state's transfer dipole moment, balance, transfer charge, dynamical response, and induced-charge distribution to identify which excitations are plasmonic in character.

Comparison of multiple support excitation solution techniques for piping systems

International Nuclear Information System (INIS)

Sterkel, H.P.; Leimbach, K.R.

1980-01-01

Design and analysis of nuclear power plant piping systems exposed to a variety of dynamic loads often require multiple support excitation analysis by modal or direct time integration methods. Both methods have recently been implemented in the computer program KWUROHR for static and dynamic analysis of piping systems, following the previous implementation of the multiple support excitation response spectrum method (see papers K 6/15 and K 6/15a of the SMiRT-4 Conference). The results of multiple support excitation response spectrum analyses can be examined by carrying out the equivalent time history analyses which do not distort the time phase relationship between the excitations at different support points. A frequent point of discussion is multiple versus single support excitation. A single support excitation analysis is computationally straightforward and tends to be on the conservative side, as the numerical results show. A multiple support excitation analysis, however, does not incur much more additional computer cost than the expenditure for an initial static solution involving three times the number, L, of excitation levels, i.e. 3L static load cases. The results are more realistic than those from a single support excitation analysis. A number of typical nuclear plant piping systems have been analyzed using single and multiple support excitation algorithms for: (1) the response spectrum method, (2) the modal time history method via the Wilson, Newmark and Goldberg integration operators and (3) the direct time history method via the Wilson integration operator. Characteristic results are presented to compare the computational quality of all three methods. (orig.)

Towards a universal scaling for broadband turbulent noise in internal flow devices

NARCIS (Netherlands)

Jong, A.T. de; Golliard, J.

2013-01-01

An investigation is performed on the scalability of broadband noise sources from separated flows in internal pipe systems. Broadband sources from for example wellhead chokes, bends and valves can potentially excite subsea manifolds through fluid acoustic coupling and fluid structural coupling. The

Resonance Raman spectra of organic molecules absorbed on inorganic semiconducting surfaces: Contribution from both localized intramolecular excitation and intermolecular charge transfer excitation

International Nuclear Information System (INIS)

Ye, ChuanXiang; Zhao, Yi; Liang, WanZhen

2015-01-01

The time-dependent correlation function approach for the calculations of absorption and resonance Raman spectra (RRS) of organic molecules absorbed on semiconductor surfaces [Y. Zhao and W. Z. Liang, J. Chem. Phys. 135, 044108 (2011)] is extended to include the contribution of the intermolecular charge transfer (CT) excitation from the absorbers to the semiconducting nanoparticles. The results demonstrate that the bidirectionally interfacial CT significantly modifies the spectral line shapes. Although the intermolecular CT excitation makes the absorption spectra red shift slightly, it essentially changes the relative intensities of mode-specific RRS and causes the oscillation behavior of surface enhanced Raman spectra with respect to interfacial electronic couplings. Furthermore, the constructive and destructive interferences of RRS from the localized molecular excitation and CT excitation are observed with respect to the electronic coupling and the bottom position of conductor band. The interferences are determined by both excitation pathways and bidirectionally interfacial CT

Pulsed rf excited spectrometer having improved pulse width control

International Nuclear Information System (INIS)

1977-01-01

RF excitation for a spectrometer is obtained by pulse width modulating an RF carrier to produce the desired broadband RF exciting spectrum. The RF excitation includes a train of composite RF pulses, each composite pulse having a primary pulse portion of a first RF phase and a second pulse portion of a second RF phase opposite that of the first. In this manner, the finite rise and fall times of the primary pulse portion are compensated for by the corresponding rise and fall times of the secondary pulse portion. The primary pulse portion is lengthened by an amount equal to the secondary pulse portion so that the secondary pulse portion cancels the added primary pulse portion. In a spectrometer, the compensating second pulse component removes certain undesired side bands of the RF excitation caused by the finite rise and fall times of the applied RF pulses. The compensating second pulse component removes certain undesired side bands associated with each of the resonant lines of the excited resonance spectrum of the sample under analysis, particularly for wide band RF excitation

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

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

Radiation from an excited vortex in the Abelian Higgs model

International Nuclear Information System (INIS)

Arodz, H.; Hadasz, L.

1996-01-01

An excited vortex in the Abelian Higgs model is investigated with the help of a polynomial approximation. The excitation consists of the longitudinal component of a vector field trapped by the vortex. The energy and profile of the excitation as well as its back reaction on the vortex are found in the case of small κ. It turns out that the width of the excited vortex oscillates in time. Moreover, the vector field has a radiative long range component. Also, an upper bound on the amplitude of the excitation is found. copyright 1996 The American Physical Society

Cross sections for the vibrational excitation of the H2 X 1Σ+g(v) levels generated by electron collisional excitation of the higher singlet states

International Nuclear Information System (INIS)

Hiskes, J.R.

1991-01-01

The excitation cross sections, σ(v,v double-prime), for an H 2 molecule initially in any one of the 15 vibrational levels, v belonging to the ground electronic state and excited to a final vibrational level, v double-prime are evaluated for direct excitations via all members of the excited electronic singlet spectrum. Account is taken of predissociation, autoionization, and radiative decay of the excited electronic spectrum that leads to a final population distribution for the ground electronic state, X 1 Σ + g (v double-prime). For v=0, account is taken explicitly of transitions via the B, C, B', and D electronic states in evaluating the cross sections. The additional contribution of excitations via all Rydberg states lying above the D state enhances these cross sections by approximately 10%. For v>0, cross sections are evaluated taking explicit account of transitions through the B and C states; higher singlet excitations enhance these values by 25%. The choice of the reference total cross sections remains a subjective one, causing the values calculated here to have a possible uncertainty of +20% -30% . For excitations occurring within a hydrogen discharge, collisional excitation-ionization events among the intermediate singlet states will effectively quench the v, v double-prime excitation process for discharge densities in excess of the range 10 15 --10 16 electrons/cm -3

Choice of excitation source for determination of rare earth elements with radioisotope excited X ray fluorescence