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Sample records for highly doubly excited

  1. Photoionization study of doubly-excited helium at ultra-high resolution

    SciTech Connect

    Kaindl, G.; Schulz, K.; Domke, M.

    1997-04-01

    Ever since the pioneering work of Madden & Codling and Cooper, Fano & Prats on doubly-excited helium in the early sixties, this system may be considered as prototypical for the study of electron-electron correlations. More detailed insight into these states could be reached only much later, when improved theoretical calculations of the optically-excited {sup 1}P{sup 0} double-excitation states became available and sufficiently high energy resolution ({delta}E=4.0 meV) was achieved. This allowed a systematic investigation of the double-excitation resonances of He up to excitation energies close to the double-ionization threshold, I{sub infinity}=79.003 eV, which stimulated renewed theoretical interest into these correlated electron states. The authors report here on striking progress in energy resolution in this grazing-incidence photon-energy range of grating monochromators and its application to hitherto unobservable states of doubly-excited He. By monitoring an extremely narrow double-excitation resonance of He, with a theoretical lifetime width of less than or equal to 5 {mu}eV, a resolution of {delta}E=1.0 meV (FWHM) at 64.1 eV could be achieved. This ultra-high spectral resolution, combined with high photon flux, allowed the investigation of new Rydberg resonances below the N=3 ionization threshold, I{sub 3}, as well as a detailed comparison with ab-initio calculations.

  2. High resolution study of the six lowest doubly excited vibrational states of PH 2D

    NASA Astrophysics Data System (ADS)

    Leroy, C.; Ulenikov, O. N.; Bekhtereva, E. S.; Onopenko, G. A.; Chudinova, T. D.

    2005-12-01

    The five lowest doubly excited deformational vibrational bands ν4 + ν6, 2 ν6, ν3 + ν4, ν3 + ν6, and 2 ν3 of PH 2D have been recorded for the first time using a Bruker 120 HR interferometer with a resolution 0.0033 cm -1 and analysed. Some transitions belonging to a very weak band 2 ν4 have been also assigned. From the fit 24 and 86, respectively, diagonal and resonance interaction parameters were obtained which reproduce 1089 upper energy levels obtained from more than 4600 assigned transitions with the rms deviation of 0.00059 cm -1.

  3. Mirroring Doubly Excited Resonances in Argon

    SciTech Connect

    Canton-Rogan, S. E.; Wills, A. A.; Gorczyca, T. W.; Wiedenhoeft, M.; Nayandin, O.; Liu, Chien-Nan; Berrah, N.

    2000-10-09

    New features are revealed in the low-energy photoionization spectrum of Ar by critically combining high photon resolution and differential photoelectron spectroscopic techniques. Two LS -forbidden doubly excited resonances are seen in the 3p{sup -1}{sub 3/2,1/2} partial cross sections which exhibit mirroring profiles, resulting in complete cancellation in the total photoionization cross section, as was predicted by Liu and Starace [Phys.Rev.A 59, R1731 (1999)]. These results demonstrate that a new class of weakly spin-orbit induced, mirroring resonances should be observable in partial, but not in total, collisional cross sections involving atoms, molecules, and solids in general.

  4. Quantification of Entanglement Entropies for Doubly Excited States in Helium

    NASA Astrophysics Data System (ADS)

    Lin, Chien-Hao; Ho, Yew Kam

    2015-05-01

    In this work, we study the quantum entanglement for doubly excited resonance states in helium by using highly correlated Hylleraas type functions to represent such states of the two-electron system. The doubly-excited resonance states are determined by calculation of density of resonance states under the framework of the stabilization method. The spatial (electron-electron orbital) entanglement measures for the low-lying doubly excited 2 s 2, 2 s3 s, and 2 p 2 1 S e states are carried out. Once a resonance state wave function is obtained, the linear entropy and von Neumann entropy for such a state are quantified using the Schmidt-Slater decomposition method. To check the consistence, linear entropy is also determined by solving analytically the needed four-electron (12-dimensional) integrals.

  5. Reluctance and doubly-excited reluctance motors

    NASA Astrophysics Data System (ADS)

    Heyne, C. J.; El-Antably, A. M.

    1984-11-01

    Since the energy crisis in 1974, there was increasing awareness of conserving energy. Industrial ac motors from 1 to 125 hp are estimated to consume 60% of the total electricity produced in the United States. Significant energy conservation could be achieved if the efficiency of these motors is improved. The work described was sponsored by the Division of Electric Energy Systems (EES) of the United States Department of Energy (DOE) through a subcontract with the Power Systems Technology Program at the Oak Ridge National Laboratory (Oak Ridge, Tennessee, USA). The design, analysis, and test of two types of motors designed to have a high efficiency and power factor are described. The first type, reluctance motors (RMs), are similar to synchronous motors but without dc excitation. A novel 3-phase RM was designed and tested, and it was found to have superior efficiency when compared with a similar induction motor.

  6. Reluctance and doubly-excited reluctance motors

    SciTech Connect

    Heyne, C.J.; El-Antably, A.M.

    1984-11-01

    Since the energy crisis in 1974, there has been increasing awareness of conserving energy. Industrial ac motors from 1 to 125 hp are estimated to consume 60% of the total electricity produced in the United States. Significant energy conservation could be achieved if the efficiency of these motors is improved. The work described in this report was sponsored by the Division of Electric Energy Systems (EES) of the United States Department of Energy (DOE) through a subcontract with the Power Systems Technology Program at the Oak Ridge National Laboratory (Oak Ridge, Tennessee, USA). This work deals with the design, analysis, and test of two types of motors designed to have a high efficiency and power factor. The first type, reluctance motors (RMs), are similar to synchronous motors but without dc excitation. A novel 3-phase RM has been designed and tested, and it was found to have superior efficiency when compared with a similar induction motor.

  7. S-wave triplet doubly-excited states 3Se of Li+ below the N=2 excitation threshold of Li2+

    NASA Astrophysics Data System (ADS)

    Gien, T. T.

    2009-11-01

    The Harris-Nesbet variational method was considered for the determination of the series a and b of S-wave triplet doubly-excited-state resonances 3Se of Li+ below the N=2 excitation threshold of Li2+. Because of the high accuracy of our numerical method, we succeeded in determining a greatest number of these doubly-excited states below this threshold, including those lying very close to the threshold. Five of these high-lying doubly excited states were determined by us for the first time.

  8. Observation of doubly excited levels in lithiumlike and beryliumlike titanium

    NASA Astrophysics Data System (ADS)

    Smith, A. J.; Beiersdorfer, P.; Harris, C. L.; Wong, K.; Chen, M.

    2002-10-01

    The satellite spectrum of heliumlike titanium has been studied using the Lawrence Livermore National Laboratory electron beam ion trap, EBIT II and a high resolution Bragg crystal spectrometer in von Hámos geometry. We initially ionize the titanium atoms to the heliumlike charge state, and then select an electron beam energy that overlaps the excitation energy for the KLM series of resonances. This allows us to populate doubly excited levels in lithiumlike TiXX as well as beryliumlike TiXIX by dielectronic remombination. We observe spectra of x-ray photons emitted at 90^rc to the electron beam. We have also calculated the photon energies, excitation energies, and resonance strengths of these resonances using an MCDF theory, and we find good agreement between the theoretical and experimental results. We gratefully acknwoledge support by the U. S. Office of Basic Energy Science, Chemical Sciences Division, and the LLNL Research Collaborations Program for HBCU's. This work was performed under the auspices of U. S. Department of Energy by Morehouse under contract No. DE-FG02-98ER14877, and by LLNL under contract No. W-7405-ENG-48.

  9. He photoionization dominated by doubly excited resonances

    SciTech Connect

    Chang, T.N.; Zhen, M.

    1993-05-01

    We present the theoretical He photoionization, cross sections from the ground and the {sup 1,3}S bound excited states using a B-spline based configuration-interaction procedure for continuum (CIC). The resonant structures associated with selected sp,2n{sup {plus_minus}} and 2pnd {sup 1,3}P autoionization series below the He{sup +} N=2 threshold will be expressed quantitatively in terms of their resonant energies, widths, and peak cross sections. Comparisons with earlier theoretical results and recent experimental measurement will be presented. The nonresonant spectra from the 1s2s {sup 1,3}S metastable states will also be reexamined.

  10. Wave packet dynamics in doubly excited states of He

    NASA Astrophysics Data System (ADS)

    Feist, Johannes; Nagele, Stefan; Persson, Emil; Burgdörfer, Joachim; Schneider, Barry

    2007-06-01

    We have developed a method for the ab initio simulation of the interaction of ultrashort laser pulses with helium atoms. We expand the two-electron Schr"odinger equation in coupled spherical harmonics and perform direct time integration utilizing either the Arnoldi-Lanczos or the Leapfrog method. The spatial discretization is performed in an FEDVR basis [1]. This allows for a numerically accurate description while possessing desirable computational features, e.g. a block-diagonal form of the kinetic energy matrix. We will present results on electron-electron correlation and wave packet dynamics in He. By using a suitable combination of attosecond XUV/EUV pulses, we prepare a wave packet in the doubly excited states of helium. The motion of this wave packet can be observed by using a probe pulse to induce ionization. We aim for a detailed understanding of the process by a careful study of the ionized electrons, e.g. by investigating doubly differential momentum spectra. [enumi] *B. I. Schneider and L. A. Collins. J. Non-Cryst. Solids 351, 1551.

  11. Doubly excited states of the hydrogen negative ion and helium atom in astrophysical plasmas

    SciTech Connect

    Jiang Pinghui; Kar, Sabyasachi; Zhou, Y.

    2013-01-15

    The nonthermal effects on the doubly excited resonance states of the hydrogen negative ion and helium atom are investigated in Lorentzian astrophysical plasma environments using highly correlated Hylleraas-type wave functions in the framework of the stabilization method. Resonance parameters (resonance position and width) are reported for the first time as functions of the spectral index and plasma parameter. The screening effects are more pronounced in the stronger screening region.

  12. Partial cross sections of doubly excited helium below the ionization threshold I{sub 7}

    SciTech Connect

    Jiang, Y.H.; Puettner, R.; Poiguine, M.; Kaindl, G.; Hentges, R.; Viefhaus, J.; Becker, U.; Rost, J.M.

    2004-04-01

    Partial photoionization cross sections (PCSs), {sigma}{sub n}, leading to final ionic states of helium, He{sup +}(n), were measured at BESSY II in the region of doubly excited helium up to the ionization threshold I{sub 7} of He{sup +}. The experiments were performed with a time-of-flight (TOF) electron spectrometer and high photon resolution, {delta}E congruent with 6 meV. The results of these measurements are a most critical assessment of the decay dynamics of double-excitation resonances and agree well with those of recent eigenchannel R-matrix calculations. They also confirm the propensity rules set up for the autoionization of doubly excitated states. The mirroring behavior in the PCSs predicted recently by Liu and Starace is only partially observed. By discussing the formulas given by these authors in a more general context, the specific behavior of the PCSs of helium with respect to mirroring can be understood. The mirroring compensation properties between the 'fractional partial cross sections' {gamma}{sub P}={sigma}{sub P}/{sigma}{sub T} and {gamma}{sub Q}={sigma}{sub Q}/{sigma}{sub T}, with {sigma}{sub T}={sigma}{sub P}+{sigma}{sub Q}, are introduced and discussed.

  13. Transient model of a doubly excited reluctance motor

    SciTech Connect

    Xu, L.; Liang, F.; Lipo, T.A. . Dept. of Electrical and Computer Engineering)

    1991-03-01

    A transient machine model of a doubly fed reluctance motor is derived by means of winding function and d-q transformation theory. The machine consists of a double wound stator having four and eight pole sets. The rotor is equipped with six poles. The machine, related to the Hunt motor, has a synchronous speed of a twelve pole machine. Comparison of simulated to tested results indicates that the higher harmonics in the motor inductances are important for predicting current waveform.

  14. High Performance Variable Speed Drive System and Generating System with Doubly Fed Machines

    NASA Astrophysics Data System (ADS)

    Tang, Yifan

    Doubly fed machines are another alternative for variable speed drive systems. The doubly fed machines, including doubly fed induction machine, self-cascaded induction machine and doubly excited brushless reluctance machine, have several attractive advantages for variable speed drive applications, the most important one being the significant cost reduction with a reduced power converter rating. With a better understanding, improved machine design, flexible power converters and innovated controllers, the doubly fed machines could favorably compete for many applications, which may also include variable speed power generations. The goal of this research is to enhance the attractiveness of the doubly fed machines for both variable speed drive and variable speed generator applications. Recognizing that wind power is one of the favorable clean, renewable energy sources that can contribute to the solution to the energy and environment dilemma, a novel variable-speed constant-frequency wind power generating system is proposed. By variable speed operation, energy capturing capability of the wind turbine is improved. The improvement can be further enhanced by effectively utilizing the doubly excited brushless reluctance machine in slip power recovery configuration. For the doubly fed machines, a stator flux two -axis dynamic model is established, based on which a flexible active and reactive power control strategy can be developed. High performance operation of the drive and generating systems is obtained through advanced control methods, including stator field orientation control, fuzzy logic control and adaptive fuzzy control. System studies are pursued through unified modeling, computer simulation, stability analysis and power flow analysis of the complete drive system or generating system with the machine, the converter and the control. Laboratory implementations and tested results with a digital signal processor system are also presented.

  15. Photoionization dominated by doubly excited resonances for Be and its isoelectronic sequence

    SciTech Connect

    Chang, T.N.; Zhu, L.

    1993-05-01

    We present the photoionization cross sections the ground and a few selected bound excited states of Be using a B-spline based configuration-interaction procedure for continuum (CIC). The resonant structures dominated by the doubly excited autoionization series will be examined in detail. Our calculation has shown that the strong overlap between the 2p(n+1)s and 2pnd {sup 1}P resonances seen in the ground state photoionization spectrum is completely removed in the spectrum originated from the bound excited state. Our calculated resonant widths vary smoothly as functions of the effective quantum number v and approach approximately an {nu}{sup 3}-dependence. We will also present the variation of the doubly excited resonance structures as Z increases along the Be-isoelectronic sequence.

  16. Autoionizing doubly-excited states of 3Σg- symmetry of H2

    NASA Astrophysics Data System (ADS)

    Argoubi, F.; Telmini, M.; Jungen, Ch.

    2015-01-01

    We report R-matrix calculations of doubly-excited 3Σg- states of molecular hydrogen corresponding to 3d˜πnℓ˜π configurations. These states form Rydberg series converging to the 3d˜π series limit. They lie in the continuum of the doubly-excited states of 3Σg- symmetry built on the 2p˜π ion core, and therefore they are autoionized. Calculations of resonance positions and widths are presented.

  17. Few-valence-particle excitations around doubly magic {sup 132}Sn

    SciTech Connect

    Daly, P.J.; Zhang, C.T.; Bhattacharyya, P.

    1996-11-01

    Prompt {gamma}-ray cascades in neutron-rich nuclei around doubly-magic {sup 132}Sn have been studied using a {sup 248}Cm fission source. Yrast states located in the N = 82 isotones {sup 134}Te and {sup 135}I are interpreted as valence proton and neutron particle-hole core excitations with the help of shell model calculations employing empirical nucleon-nucleon interactions from both {sup 132}Sn and {sup 208}Pb regions.

  18. Interplay between collective and single particle excitations around neutron-rich doubly-magic nuclei

    NASA Astrophysics Data System (ADS)

    Leoni, S.

    2016-05-01

    The excitation spectra of nuclei with one or two particles outside a doubly-magic core are expected to be dominated, at low energy, by the couplings between phonon excitations of the core and valence particles. A survey of the experimental situation is given for some nuclei lying in close proximity of neutron-rich doubly-magic systems, such as 47,49Ca, 133Sb and 210Bi. Data are obtained with various types of reactions (multinucleon transfer with heavy ions, cold neutron capture and neutron induced fission of 235U and 241Pu targets), with the employment of complex detection systems based on HPGe arrays. A comparison with theoretical calculations is also presented, in terms of large shell model calculations and of a phenomenological particle-phonon model. In the case of 133Sb, a new microscopic "hybrid" model is introduced: it is based on the coupling between core excitations (both collective and non-collective) of the doubly-magic core and the valence nucleon, using the Skyrme effective interaction in a consistent way.

  19. Purely-long-range krypton molecules in singly and doubly excited binding potentials

    SciTech Connect

    Smith, Z. S.; Harmon, A.; Banister, J.; Norman, R.; Hoogeboom-Pot, K.; Walhout, M.

    2010-01-15

    Diatomic potentials for krypton are computed and also probed experimentally. For a probe-laser wavelength near 811 nm, several strong dipole-dipole interactions produce purely-long-range potential wells in the singly excited manifold of (s+p) potentials and in the doubly excited manifold of (p+p) and (s+d) potentials. Evidence of resonant photoassociation into bound states of these potential wells is observed in the emission of ions and ultraviolet photons from a magneto-optically trapped krypton cloud.

  20. Complex-Scaling Treatment for Doubly Excited Inter-Shell Resonances in H- Interacting with Screened Coulomb (Yukawa) Potentials

    NASA Astrophysics Data System (ADS)

    Ho, Y. K.; Kar, S.

    2012-10-01

    The doubly-excited inter-shell resonance states of the hydrogen negative ion with screened Coulomb potentials are investigated in the framework of complex-scaling method. Highly correlated wave functions with terms up to 1078 in Hylleraas coordinates are used. The resonance parameters for the 2 s3 s 1 S e associated with the H ( N = 2) threshold and the 3 s4 s 1 S e state associated with the H ( N = 3) threshold for various screening strengths are reported. Comparisons are made with other available data in the literature.

  1. Doubly excited 3Pe resonance states of two-electron positive ions in Debye plasmas

    NASA Astrophysics Data System (ADS)

    Hu, Xiao-Qing; Wang, Yang; Jiang, Zishi; Jiang, Pinghui; Kar, Sabyasachi

    2015-11-01

    We investigate the doubly excited 3Pe resonance states of two-electron positive ions Li+, Be2+, B3+, and C4+ by employing correlated exponential wave functions. In the framework of the stabilization method, we calculate two series (3pnp and 3dnd) of 3Pe resonances below the N = 3 threshold. The 3Pe resonance parameters (resonance energies and widths) are reported for the first time as a function of the screening parameter. For free-atomic cases, comparisons are made with the reported results and few resonance states are reported for the first time.

  2. Neutral resonant ionization in a H- plasma source: Potential of doubly excited **H-

    NASA Astrophysics Data System (ADS)

    Vogel, J. S.

    2016-02-01

    Hydrogen plasmas are optically dense to Lyman-α radiation, maintaining *H(n = 2) neutral atoms that may undergo neutral resonant ionization to **H-. One state, **H-(2p2 3Pe), is thought bound at 9.7 meV with a several nanosecond lifetime while all others are unbound resonances. Collision dynamics of two *H(2s) shows that an ionic pair of (p, **H-) resolves at least three long-standing collision experiments. The doubly excited anion also has a path to the unexcited ion pair whose only physical distinction is that both (p, H-) have energy of 3.7 eV.

  3. Excited-state spectroscopy of singly, doubly and triply-charmed baryons from lattice QCD

    SciTech Connect

    Padmanath, M.; Edwards, Robert G.; Mathur, Nilmani; Peardon, Michael

    2014-07-01

    We present the ground and excited state spectra of singly, doubly and triply-charmed baryons by using dynamical lattice QCD. A large set of baryonic operators that respect the symmetries of the lattice and are obtained after subduction from their continuum analogues are utilized. These operators transform as irreducible representations of SU(3)F symmetry for flavour, SU(4) symmetry for Dirac spins of quarks and O(3) symmetry for orbital angular momenta. Using novel computational techniques correlation functions of these operators are generated and the variational method is exploited to extract excited states. The lattice spectra that we obtain have baryonic states with well-defined total spins up to 7/2 and the low lying states remarkably resemble the expectations of quantum numbers from SU(6)ⓍO(3) symmetry.

  4. Role of Coulomb repulsion in correlated-electron emission from a doubly excited state in nonsequential double ionization of molecules

    NASA Astrophysics Data System (ADS)

    Huang, Cheng; Guo, Wenliang; Zhou, Yueming; Wu, Zhengmao

    2016-01-01

    With the classical ensemble model, we investigate nonsequential double ionization of aligned molecules by few-cycle laser pulses at low intensity, where the two electrons finally are ionized through a transition doubly excited state induced by recollision. The correlated electron momentum distribution of parallel molecules exhibits the line-shaped structure parallel to the diagonal. Our analysis indicates that besides the ionization time difference of two electrons from the doubly excited state, the final-state e-e Coulomb repulsion plays a vital role in the formation of the line-shaped structural momentum distribution. For perpendicular molecules, due to the prominent near half-cycle ionization time difference between the two electrons from the doubly excited state, the momentum distribution shows clear anticorrelation behavior.

  5. Series of doubly excited states 3Se of Li+ below the N = 2 threshold of Li2+

    NASA Astrophysics Data System (ADS)

    Gien, T. T.

    2010-01-01

    We use a numerical procedure developed earlier, based on the Harris-Nesbet variational calculation of phase shifts for elastic scattering of electron from Li2+ (Gien 2003 J. Phys. B: At. Mol. Opt. Phys. 36 2291), to determine the series of doubly excited states 3Se of Li+ at energies below the N = 2 threshold of Li2+. Our results of position and width for the low-lying doubly excited states are to be compared with those obtained by other research groups employing various different numerical methods for their calculations. This work provides a new set of higher lying doubly excited state resonances 3Se of Li+ to be compared with those determined with a completely different numerical method by Chung and Lin (1998 At. Data and Nucl. Data Tables 69 101). In addition, we are also able to determine five more of these doubly excited states, 3Se(2,11a), 3Se(2,12a), 3Se(2,10b), 3Se(2,11b) and 3Se(2,12b), which lie very close to the N = 2 excitation threshold of Li2+. We discuss the results of our work in comparison with those of other research groups, stressing the significant accuracy of our method and its relevant research perspective. Research work supported by the NSERC of Canada.

  6. Obtaining Hartree-Fock and density functional theory doubly excited states with Car-Parrinello density matrix search

    NASA Astrophysics Data System (ADS)

    Liang, Wenkel; Isborn, Christine M.; Li, Xiaosong

    2009-11-01

    The calculation of doubly excited states is one of the major problems plaguing the modern day excited state workhorse methodology of linear response time dependent Hartree-Fock (TDHF) and density function theory (TDDFT). We have previously shown that the use of a resonantly tuned field within real-time TDHF and TDDFT is able to simultaneously excite both the α and β electrons to achieve the two-electron excited states of minimal basis H2 and HeH+ [C. M. Isborn and X. Li, J. Chem. Phys. 129, 204107 (2008)]. We now extend this method to many electron systems with the use of our Car-Parrinello density matrix search (CP-DMS) with a first-principles fictitious mass method for wave function optimization [X. Li, C. L. Moss, W. Liang, and Y. Feng, J. Chem. Phys. 130, 234115 (2009)]. Real-time TDHF/TDDFT is used during the application of the laser field perturbation, driving the electron density toward the doubly excited state. The CP-DMS method then converges the density to the nearest stationary state. We present these stationary state doubly excited state energies and properties at the HF and DFT levels for H2, HeH+, lithium hydride, ethylene, and butadiene.

  7. Dressing effects in the attosecond transient absorption spectra of doubly excited states in helium

    NASA Astrophysics Data System (ADS)

    Argenti, L.; Jiménez-Galán, Á.; Marante, C.; Ott, C.; Pfeifer, T.; Martín, F.

    2015-06-01

    Strong-field manipulation of autoionizing states is a crucial aspect of electronic quantum control. Recent measurements of the attosecond transient absorption spectrum (ATAS) of helium dressed by a few-cycle visible pulse [C. Ott et al., Nature (London) 516, 374 (2014), 10.1038/nature14026] provide evidence of the inversion of Fano profiles. With the support of accurate ab initio calculations that reproduce the results of the latter experiment, here we investigate the new physics that arise from ATAS when the laser intensity is increased. In particular, we show that (i) previously unnoticed signatures of the dark 2 p21S doubly excited state are observed in the experimental spectrum, (ii) inversion of Fano profiles is predicted to be periodic in the laser intensity, and (iii) the ac Stark shift of the higher terms in the s p2,n + autoionizing series exceeds the ponderomotive energy, which is the result of a genuine two-electron contribution to the polarization of the excited atom.

  8. Doubly electron-attached and doubly ionised equation-of-motion coupled-cluster methods with full and active-space treatments of 4-particle-2-hole and 4-hole-2-particle excitations: the role of orbital choices

    NASA Astrophysics Data System (ADS)

    Shen, Jun; Piecuch, Piotr

    2014-03-01

    We have recently developed the full and active-space doubly electron-attached (DEA) and doubly ionised (DIP) equation-of-motion coupled-cluster (EOMCC) methods with up to 4-particle-2-hole (4p-2h) and 4-hole-2-particle (4h-2p) excitations. By examining the low-lying singlet and triplet states of the methylene, (HFH)-, and trimethylenemethane biradicals, and a few different types of molecular orbitals (MOs) to describe the corresponding wave functions, including the restricted or restricted open-shell Hartree-Fock orbitals of the target N-electron species and their counterparts associated with the (N ∓ 2)-electron reference systems, we demonstrate that the DEA- and DIP-EOMCC approaches with the full and active-space treatments of 4p-2h and 4h-2p excitations provide high-accuracy results which are not only in perfect agreement with one another, but also practically insensitive to the choice of the underlying MO basis. This should be contrasted with the DEA- and DIP-EOMCC methods truncated at 3p-1h/3h-1p excitations, which are generally less accurate and more sensitive to the types of orbitals used in the calculations.

  9. Observation of Doubly-Excited States in CALCIUM(17+) and Inner Shell-Photoexcitations in Argon, Potassium and Rubidium

    NASA Astrophysics Data System (ADS)

    Suleiman, Jamal A.

    High resolution X-ray spectroscopy is used to study (A) simultaneous electron-excitation and electron capture in the collision of calcium ions with argon atoms; these studies are important because of the close relationship to dielectronic recombination (DR) which plays an important role in energy-transfer processes in astrophysical and laboratory plasmas; (B) single and double inner-shell photoexcitations of potassium, rubidium and argon; these measurements can lead to very precise tests of electron correlation effects, such as Breit interaction, and QED effects in many electron systems. In the first case, Ca^{18+ } and Ca^{19+} ions from the ATLAS accelerator at Argonne National Laboratory, at energies near 100 MeV, were directed to an argon gas target. X-ray spectra near 3.9 KeV were collected using a high-resolution X-ray spectrometer. We have resolved transitions from doubly-excited 1s2lnl^ ' states to singly-excited 1s ^2nl^' states in lithium -like calcium. Comparison of the experimental wavelengths and intensities with relativistic Hartree-Fock calculations shows very good agreement. In the second case, we have obtained high spectral resolution absorption spectra of potassium near K-, KN -, and KM-edges, rubidium near K- and KO edges, and argon near K-, KM-, and KL-edges. The measurements were made at the X-24A and X-23A2 beamlines at the National Synchrotron Light Source at Brookhaven National Laboratory. Preliminary identifications of most the peaks are made using Dirac Hartree-Fock calculations. Comparisons of the experimental wavelengths and intensities with relativistic Hartree-Fock calculations show very good agreement.

  10. Attosecond XUV absorption spectroscopy of doubly excited states in helium atoms dressed by a time-delayed femtosecond infrared laser

    NASA Astrophysics Data System (ADS)

    Yang, Z. Q.; Ye, D. F.; Ding, Thomas; Pfeifer, Thomas; Fu, L. B.

    2015-01-01

    In the present paper, we investigate the time-resolved transient absorption spectroscopy of doubly excited states of helium atoms by solving the time-dependent two-electron Schrödinger equation numerically based on a one-dimensional model. The helium atoms are subjected to an extreme ultraviolet (XUV) attosecond pulse and a time-delayed infrared (IR) few-cycle laser pulse. A superposition of doubly excited states populated by the XUV pulse is identified, which interferes with the direct ionization pathway leading to Fano resonance profiles in the photoabsorption spectrum. In the presence of an IR laser, however, the Fano line profiles are strongly modified: A shifting, splitting, and broadening of the original absorption lines is observed when the XUV attosecond pulse and infrared few-cycle laser pulse overlap in time, which is in good agreement with recent experimental results. At certain time delays, we observe symmetric Lorentz, inverted Fano profiles, and even negative absorption cross sections indicating that the XUV light can be amplified during the interaction with atoms. We further prove that the above pictures are general for different doubly excited states by suitably varying the frequency of the IR field to coherently couple the corresponding states.

  11. Extended similarity transformed equation-of-motion coupled cluster theory (extended-STEOM-CC): Applications to doubly excited states and transition metal compounds

    NASA Astrophysics Data System (ADS)

    Nooijen, Marcel; Lotrich, Victor

    2000-07-01

    The diagonalization manifold in similarity transformed equation-of-motion coupled cluster (STEOM-CC) theory is extended to include doubly excited determinants. In the resulting extended-STEOM approach accurate results are obtained for doubly excited states in small model systems for which full configuration interaction (CI) benchmark results are available (˜0.1 eV errors). On the other hand, extended-STEOM results are found to be virtually identical (<0.1 eV shifts) to the original STEOM results for states that are dominated by single excitations, at least in prototypical organic molecules. The extended-STEOM method is also applied to the transition metal complexes TiCl4, Ni(CO)4, and MnO4-, and yields improved results compared to STEOM and EOM-CCSD. For highly correlated systems, like the permangenate anion, results are not yet fully satisfactory however. In these cases the dominant source of error appears to be the description of ground, ionized, and attached states that underly the similarity transformed Hamiltonian in the extended-STEOM approach.

  12. High spin states and isomeric decays in doubly-odd 208Fr

    NASA Astrophysics Data System (ADS)

    Kanjilal, D.; Bhattacharya, S.; Goswami, A.; Kshetri, R.; Raut, R.; Saha, S.; Bhowmik, R. K.; Gehlot, J.; Muralithar, S.; Singh, R. P.; Jnaneswari, G.; Mukherjee, G.; Mukherjee, B.

    2010-10-01

    Neutron deficient isotopes of francium ( Z=87, N˜121-123) as excited nuclei were produced in the fusion-evaporation reaction: 197Au( 16O, xn) 213 - xFr at 100 MeV. The γ rays from the residues were observed through the high sensitivity Germanium Clover detector array INGA. The decay of the high spin states and the isomeric states of the doubly-odd 208Fr nuclei, identified from the known sequence of ground state transitions, were observed. The half-lives of the E=194(2) keV isomeric transition, known from earlier observations, was measured to be T=233(18) ns. A second isomeric transition at E=383(2) keV and T=33(7) ns was also found. The measured half-lives were compared with the corresponding single particle estimates, based on the level scheme obtained from the experiment.

  13. Spin-dependent localized Hartree-Fock density-functional calculation of singly, doubly, and triply excited and Rydberg states of He- and Li-like ions

    SciTech Connect

    Zhou Zhongyuan; Chu, Shih-I

    2005-02-01

    A spin-dependent density-functional approach for the calculation of highly and multiply excited state of atomic system is proposed based on the localized Hartree-Fock density-functional method and Slater's diagonal sum rule. In this approach, electron spin orbitals in an electronic configuration are obtained first by solving the Kohn-Sham equation with an exact nonvariational spin-dependent localized Hartree-Fock exchange potential. Then a single-Slater-determinant energy of the electronic configuration is calculated by using these electron spin orbitals. Finally, a multiplet energy of an excited state is evaluated from the single-Slater-determinant energies of the electronic configurations involved in terms of Slater's diagonal sum rule. This approach has been applied to the calculation of singly, doubly, and especially triply excited Rydberg states of He- and Li-like ions. The total energies obtained from the calculation with an exchange-only (X-only) potential are surprisingly close to those of Hartree-Fock method and the total energies from the calculation with exchange-correlation potential are in overall agreement with available theoretical and experimental data. The presented procedure provides a simple and computationally efficient scheme for the accurate calculation of highly and multiply excited Rydberg states of an atomic system within density-functional theory.

  14. Ground and excited states of doubly open-shell nuclei from ab initio valence-space Hamiltonians

    NASA Astrophysics Data System (ADS)

    Stroberg, S. R.; Hergert, H.; Holt, J. D.; Bogner, S. K.; Schwenk, A.

    2016-05-01

    We present ab initio predictions for ground and excited states of doubly open-shell fluorine and neon isotopes based on chiral two- and three-nucleon interactions. We use the in-medium similarity renormalization group to derive mass-dependent s d valence-space Hamiltonians. The experimental ground-state energies are reproduced through neutron number N =14 , beyond which a new targeted normal-ordering procedure improves agreement with data and large-space multireference calculations. For spectroscopy, we focus on neutron-rich F-2623 and Ne-2624 isotopes near N =14 ,16 magic numbers. In all cases we find agreement with experiment and established phenomenology. Moreover, yrast states are well described in 20Ne and 24Mg, providing a path toward an ab initio description of deformation in the medium-mass region.

  15. Doubly excited {sup 3}P{sup e} resonance states of two-electron positive ions in Debye plasmas

    SciTech Connect

    Hu, Xiao-Qing; Wang, Yang; Kar, Sabyasachi E-mail: karsabyasachi@yahoo.com; Jiang, Zishi; Jiang, Pinghui

    2015-11-15

    We investigate the doubly excited {sup 3}P{sup e} resonance states of two-electron positive ions Li{sup +}, Be{sup 2+}, B{sup 3+}, and C{sup 4+} by employing correlated exponential wave functions. In the framework of the stabilization method, we calculate two series (3pnp and 3dnd) of {sup 3}P{sup e} resonances below the N = 3 threshold. The {sup 3}P{sup e} resonance parameters (resonance energies and widths) are reported for the first time as a function of the screening parameter. For free-atomic cases, comparisons are made with the reported results and few resonance states are reported for the first time.

  16. Quenching of the 2pnd Po1 doubly excited states of helium by a dc electric field

    NASA Astrophysics Data System (ADS)

    Bučar, K.; Žitnik, M.; Mihelič, A.; Penent, F.; Lablanquie, P.; Palaudoux, J.; Andrić, L.; Braune, M.; Püttner, R.

    2014-07-01

    The fluorescence yield quenching of low-lying doubly excited 2pnd Po1 states is observed to depend strongly on a dc electric field strength and its orientation with respect to the polarization of the incoming photon beam. The reduction of the yield accompanied by the lifetime shortening is attributed to the Stark mixing with the neighboring 2sns Se1 states, which redirects the 2pnd Po1 decay to the prompt autoionization channel. For n ≥4, the lifetimes decrease from several hundred picoseconds down to several tens of picoseconds when an electric field in the kV/cm range is applied parallel to the photon probe polarization. Practically no lifetime change is observed for polarization perpendicular to the electric field direction. The results of the complex-scaling calculations are in a good agreement with the experimental data.

  17. Comparison of doubly labeled water with respirometry at low- and high-activity levels

    SciTech Connect

    Westerterp, K.R.; Brouns, F.; Saris, W.H.; ten Hoor, F.

    1988-07-01

    In previous studies the doubly labeled water method for measuring energy expenditure in free-living humans has been validated against respirometry under sedentary conditions. In the present investigation, energy expenditure is measured simultaneously with doubly labeled water and respirometry at low- and high-activity levels. Over 6 days, five subjects were measured doing mainly sedentary activities like desk work; their average daily metabolic rate was 1.40 +/- 0.09 (SD) times sleeping metabolic rate. Four subjects were measured twice over 3.5 days, including 2 days with heavy bicycle ergometer work, resulting in an average daily metabolic rate of 2.61 +/- 0.25 (SD) times sleeping metabolic rate. At the low-activity level, energy expenditures from the doubly labeled water method were on the average 1.4 +/- 3.9% (SD) larger than those from respirometry. At the high-activity level, the doubly labeled water method yielded values that were 1.0 +/- 7.0% (SD) lower than those from respirometry. Results demonstrate the utility of the doubly labeled water method for the determination of energy expenditure in the range of activity levels in daily life.

  18. Excitation of helium Rydberg states and doubly excited resonances in strong extreme ultraviolet fields: Full-dimensional quantum dynamics using exponentially tempered Gaussian basis sets

    SciTech Connect

    Kaprálová-Žďánská, Petra Ruth; Šmydke, Jan; Department of Radiation and Chemical Physics, Institute of Physics, Academy of Sciences of the Czech Republic, Na Slovance 2, 182 21 Prague 8 ; Civiš, Svatopluk

    2013-09-14

    Recently optimized exponentially tempered Gaussian basis sets [P. R. Kapralova-Zdanska and J. Smydke, J. Chem. Phys. 138, 024105 (2013)] are employed in quantitative simulations of helium absorption cross-sections and two-photon excitation yields of doubly excited resonances. Linearly polarized half-infinite and Gaussian laser pulses at wavelengths 38–58 nm and large intensities up to 100 TW/cm{sup 2} are considered. The emphasis is laid on convergence of the results with respect to the quality of the Gaussian basis sets (typically limited by a number of partial waves, density, and spatial extent of the basis functions) as well as to the quality of the basis set of field-free states (typically limited by the maximum rotational quantum number and maximum excitation of the lower electron). Particular attention is paid to stability of the results with respect to varying complex scaling parameter. Moreover, the study of the dynamics is preceded by a thorough check of helium energies and oscillator strengths as they are obtained with the exponentially tempered Gaussian basis sets, being also compared with yet unpublished emission wavelengths measured in electric discharge experiments.

  19. Pump-probe photoelectron velocity-map imaging of autoionizing singly excited 4s{sup 1}4p{sup 6}np{sup 1}(n=7,8) and doubly excited 4s{sup 2}4p{sup 4}5s{sup 1}6p{sup 1} resonances in atomic krypton

    SciTech Connect

    Doughty, Benjamin; Haber, Louis H.; Leone, Stephen R.

    2011-10-15

    Pump-probe photoelectron velocity-map imaging, using 27-eV high-harmonic excitation and 786-nm ionization, is used to resolve overlapping autoionizing resonances in atomic krypton, obtaining two-photon photoelectron angular distributions (PADs) for singly and doubly excited states. Two features in the photoelectron spectrum are assigned to singly excited 4s{sup 1}4p{sup 6}np{sup 1} (n = 7,8) configurations and four features provide information about double excitation configurations. The anisotropy parameters for the singly excited 7p configuration are measured to be {beta}{sub 2} = 1.61 {+-} 0.06 and {beta}{sub 4} = 1.54 {+-} 0.16 while the 8p configuration gives {beta}{sub 2} = 1.23 {+-} 0.19 and {beta}{sub 4} = 0.60 {+-} 0.15. These anisotropies most likely represent the sum of overlapping PADs from states of singlet and triplet spin multiplicities. Of the four bands corresponding to ionization of doubly excited states, two are assigned to 4s{sup 2}4p{sup 4}5s{sup 1}6p{sup 1} configurations that are probed to different J-split ion states. The two remaining doubly excited states are attributed to a previously observed, but unassigned, resonance in the vacuum-ultraviolet photoabsorption spectrum. The PADs from each of the double excitation states are also influenced by overlap from neighboring states that are not completely spectrally resolved. The anisotropies of the observed double excitation states are reported, anticipating future theoretical and experimental work to separate the overlapping PADs into the state resolved PADs. The results can be used to test theories of excited state ionization.

  20. Highly conducting and crystalline doubly doped tin oxide films fabricated using a low-cost and simplified spray technique

    NASA Astrophysics Data System (ADS)

    Ravichandran, K.; Muruganantham, G.; Sakthivel, B.

    2009-11-01

    Doubly doped (simultaneous doping of antimony and fluorine) tin oxide films (SnO 2:Sb:F) have been fabricated by employing an inexpensive and simplified spray technique using perfume atomizer from aqueous solution of SnCl 2 precursor. The structural studies revealed that the films are highly crystalline in nature with preferential orientation along the (2 0 0) plane. It is found that the size of the crystallites of the doubly doped tin oxide films is larger (69 nm) than that (27 nm) of their undoped counterparts. The dislocation density of the doubly doped film is lesser (2.08×10 14 lines/m 2) when compared with that of the undoped film (13.2×10 14 lines/m 2), indicating the higher degree of crystallinity of the doubly doped films. The SEM images depict that the films are homogeneous and uniform. The optical transmittance in the visible range and the optical band gap of the doubly doped films are 71% and 3.56 eV respectively. The sheet resistance (4.13 Ω/□) attained for the doubly doped film in this study is lower than the values reported for spray deposited fluorine or antimony doped tin oxide films prepared from aqueous solution of SnCl 2 precursor (without using methanol or ethanol).

  1. Ultrafast spectroscopy of super high frequency mechanical modes of doubly clamped beams

    NASA Astrophysics Data System (ADS)

    Ristow, Oliver; Merklein, Moritz; Grossmann, Martin; Hettich, Mike; Schubert, Martin; Bruchhausen, Axel; Grebing, Jochen; Erbe, Artur; Mounier, Denis; Gusev, Vitalyi; Scheer, Elke; Dekorsy, Thomas; Barretto, Elaine C. S.

    2013-12-01

    We use ultrafast pump-probe spectroscopy to study the mechanical vibrations in the time domain of doubly clamped silicon nitride beams. Beams with two different clamping conditions are investigated. Finite element method calculations are performed to analyse the mode spectra of both structures. By calculating the strain integral on the surface of the resonators, we are able to reproduce the effect of the detection mechanism and identify all the measured modes. We show that our spectroscopy technique combined with our modelling tools allow the investigation of several different modes in the super high frequency range (3-30 GHz) and above, bringing more information about the vibration modes of nanomechanical resonators.

  2. Effect of electric fields on the decay branching ratio of {sup 1}P{sup e} doubly excited states in helium measured by time-resolved fluorescence

    SciTech Connect

    Zitnik, Matjaz; Mihelic, A.; Bucar, K.; Penent, F.; Lablanquie, P.; Richter, R.; Alagia, M.; Stranges, S.

    2006-11-15

    We have measured the lifetimes of {sup 1}P{sup e} (n=9-12) doubly excited states in static electric fields (1-6 kV/cm) by observing the decay of the fluorescence signal as a function of time. The effects of the field on these helium states below the second ionization threshold are twofold: their excitation becomes possible due to the Stark mixing with the optically allowed {sup 1}P{sup o} series, and their lifetime is strongly modified by the opening of the autoionization channel, not accessible in zero field. Although the electric field represents only a tiny perturbation of the atomic potential, a substantial shortening of the lifetimes below 100 ps is observed. This is the simplest quantum system where the ratio of autoionization to fluorescence decay probability can be effectively controlled by an electric field of moderate strength.

  3. First excited states in doubly-odd {sup 110}Sb: Smooth band termination in the A {approx} 110 region

    SciTech Connect

    Lane, G.J.; Fossan, D.B.; Thorslund, I.

    1996-11-01

    Excited states have been identified for the first time in {sup 110}Sb in a comprehensive series of {gamma}-spectroscopy experiments, including recoil-mass and neutron-field measurements. Three high-spin decoupled bands with configurations based on 2p-2h excitations across the Z = 50 shell gap, are observed to show the features of smooth band termination, the first such observation in an odd-odd nucleus. The yrast intruder band has been connected to the low spin levels and is tentatively identified up to its predicred termination at I{sup {pi}} = (45{sup +}). Detailed configuration assignments are made through comparison with configuration-dependent cranked Nilsson-Strutinsky calculations; excellent agreement with experiment is obtained. The systematic occurrence of smoothly terminating bands in the neighboring isotopes is discussed.

  4. Self-assembly of DNA double-double crossover complexes into high-density, doubly connected, planar structures.

    PubMed

    Reishus, Dustin; Shaw, Bilal; Brun, Yuriy; Chelyapov, Nickolas; Adleman, Leonard

    2005-12-21

    We designed a molecular complex, the double-double crossover, consisting of four DNA double helices connected by six reciprocal exchanges. Atomic force micrographs suggest that double-double crossover complexes self-assemble into high-density, doubly connected, two-dimensional, planar structures. Such structures may be suitable as substrates for the deposition of nanomaterials in the creation of high-density electrical and quantum devices. We speculate about a modified double-double crossover complex that might self-assemble into high-density, doubly connected, three-dimensional structures. PMID:16351073

  5. Ultrafast spectroscopy of super high frequency mechanical modes of doubly clamped beams

    SciTech Connect

    Ristow, Oliver; Merklein, Moritz; Grossmann, Martin; Hettich, Mike; Schubert, Martin; Bruchhausen, Axel; Scheer, Elke; Dekorsy, Thomas; Barretto, Elaine C. S.; Grebing, Jochen; Erbe, Artur; Mounier, Denis; Gusev, Vitalyi

    2013-12-02

    We use ultrafast pump-probe spectroscopy to study the mechanical vibrations in the time domain of doubly clamped silicon nitride beams. Beams with two different clamping conditions are investigated. Finite element method calculations are performed to analyse the mode spectra of both structures. By calculating the strain integral on the surface of the resonators, we are able to reproduce the effect of the detection mechanism and identify all the measured modes. We show that our spectroscopy technique combined with our modelling tools allow the investigation of several different modes in the super high frequency range (3-30 GHz) and above, bringing more information about the vibration modes of nanomechanical resonators.

  6. The ground state and doubly-excited 1,3P° states of hot-dense plasma-embedded Li+ ions

    NASA Astrophysics Data System (ADS)

    Kar, S.; Ho, Y. K.

    2007-07-01

    We have investigated the ground state and the doubly excited 1,3P^circ resonance states of plasma-embedded Li+ ion. The plasma effect is taken care of by using a screened Coulomb potential obtained from the Debye model. A correlated wave function has been used to represent the correlation effect between the charged particles. The ground state of Li+ in plasmas for different screening parameters has been estimated in the framework of Rayleigh-Ritz variational principle. In addition, a total of 18 resonances (9 each for ^1P^circ and ^3P^circ states) below the n=2 Li+ thresholds has been estimated by calculating the density of states using the stabilization method. For each spin state, this includes four members in the 2snp+ (2≤ n ≤ 5) series, three members in the 2snp- (3≤ n ≤ 5) series, and two members in the 2pnd (n=3, 4) series. The resonance energies and widths for various Debye parameters ranging from infinity to a small value for these 1,3P^circ resonance states along with the ground state energies of Li+ and the Li2+ (1S), Li2+ (2S) threshold energies are reported. Furthermore, the wavelengths for the photo-absorption of lithium ion from its ground state to such ^1P^circ resonance states for different Debye lengths are also reported.

  7. Doubly excited {sup 1,3}P{sup e} resonance states of helium and the hydrogen negative ion interacting with Coulomb and screened Coulomb potentials

    SciTech Connect

    Kar, Sabyasachi; Ho, Y. K.

    2011-04-15

    We have investigated the doubly excited {sup 1,3}P{sup e} resonance states of helium and the hydrogen negative ion interacting with Coulomb and screened Coulomb potentials using exponential correlated wave functions. In the pure Coulomb case, calculations have been carried out by using the complex-coordinate rotation and the stabilization method. The {sup 1}P{sup e} resonance states of He below the N= 3, 4, and 5 thresholds of He{sup +}, and the {sup 3}P{sup e} resonance states of He below the N= 3 thresholds of He{sup +}, are reported. The 5p{sup 2} {sup 3}P{sup e} state, which has attracted recent interest, is also reported and discussed. In the screened Coulomb case, we have used the stabilization method to obtain two different series (3pnp and 3dnd) of resonance states below the N= 3 He{sup +} threshold as a function of the screening parameters. Resonance widths for the 3dnd series show some interesting behaviors. The resonance parameters (position and width) for helium and the hydrogen negation ion as functions of the screening parameters are reported.

  8. The doubly labeled water method produces highly reproducible longitudinal results in nutrition studies

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The doubly labeled water (DLW) method is considered the reference method for the measurement of energy expenditure under free-living conditions. However, the reproducibility of the DLW method in longitudinal studies is not well documented. This study was designed to evaluate the longitudinal reprodu...

  9. The Doubly Labeled Water Method Produces Highly Reproducible Longitudinal Results in Nutrition Studies12

    PubMed Central

    Wong, William W.; Roberts, Susan B.; Racette, Susan B.; Das, Sai Krupa; Redman, Leanne M.; Rochon, James; Bhapkar, Manjushri V.; Clarke, Lucinda L.; Kraus, William E.

    2014-01-01

    The doubly labeled water (DLW) method is considered the reference method for the measurement of energy expenditure under free-living conditions. However, the reproducibility of the DLW method in longitudinal studies is not well documented. This study was designed to evaluate the longitudinal reproducibility of the DLW method using 2 protocols developed and implemented in a multicenter clinical trial—the Comprehensive Assessment of Long-term Effects of Reducing Intake of Energy (CALERIE). To document the longitudinal reproducibility of the DLW method, 2 protocols, 1 based on repeated analysis of dose dilutions over the course of the clinical trial (dose-dilution protocol) and 1 based on repeated but blinded analysis of randomly selected DLW studies (test-retest protocol), were carried out. The dose-dilution protocol showed that the theoretical fractional turnover rates for 2H and 18O and the difference between the 2 fractional turnover rates were reproducible to within 1% and 5%, respectively, over 4.5 y. The Bland-Altman pair-wise comparisons of the results generated from 50 test-retest DLW studies showed that the fractional turnover rates and isotope dilution spaces for 2H and 18O, and total energy expenditure, were highly reproducible over 2.4 y. Our results show that the DLW method is reproducible in longitudinal studies and confirm the validity of this method to measure energy expenditure, define energy intake prescriptions, and monitor adherence and body composition changes over the period of 2.5–4.4 y. The 2 protocols can be adopted by other laboratories to document the longitudinal reproducibility of their measurements to ensure the long-term outcomes of interest are meaningful biologically. This trial was registered at clinicaltrials.gov as NCT00427193. PMID:24523488

  10. Static quadrupole moment of high-spin isomers in the doubly-odd {sup 214}Fr nucleus

    SciTech Connect

    Neyens, G.; Van Asbroeck, I.; Coussement, R.

    1995-06-01

    We have determined the spectroscopic quadrupole moment of two high-spin isomers ({ital I}=11 {h_bar} and {ital I}=32 {h_bar}) which have recently been identified in the doubly-odd {sup 214}Fr nucleus. The data have been extracted from a series of former level mixing spectroscopy (LEMS) measurements which had been performed to measure quadrupole moments of high-spin isomers in {sup 211,212,213}Fr isotopes. The quadrupole frequencies were measured in natural and enriched poly- and single-crystalline T1 at different temperatures.

  11. Nickel and titanium doubly doped lanthanum strontium chromite for high temperature electrochemical devices

    NASA Astrophysics Data System (ADS)

    Gupta, Sapna; Singh, Prabhakar

    2016-02-01

    Lanthanum chromite based materials are promising candidate for use as electrochemical components in high temperature electrochemical devices. In this study, nickel and titanium doubly doped lanthanum strontium chromites are developed and the effects of nickel and titanium co-doping of the chromite perovskite La0.85Sr0.15Cr1-2yNiyTiyO3-δ (0.05 ≤ y ≤ 0.3) on the electrical conductivity, chemical stability, microstructure, density, thermal expansion and electrochemical performance are measured. Density and the electrical conductivity increases with nickel concentration whereas Sr-segregation on the surface of La0.85Sr0.15Cr1-2yNiyTiyO3-δ has been observed for y ≥ 0.2 and is associated with reduction in the electrical conductivity. For y = 0.1, La0.85Sr0.15Cr1-2yNiyTiyO3-δ shows the highest electrical conductivity in air and reducing atmosphere (PO2 ∼10-24 atm). The conductivity of La0.85Sr0.15Cr1-2yNiyTiyO3-δ (y = 0.1) in reducing atmosphere (3.58 S cm-1 at 950 °C) also remains higher than the most widely investigated compositions such as (La0.75Sr0.25)0.95Cr0.5Mn0.5O3-δ (2.81 S cm-1) and (La0.75Sr0.25)0.95Cr0.7Fe0.3O3-δ (1.41 S cm-1). Smaller deviation in the oxygen stoichiometry is similarly observed for La0.85Sr0.15Cr0.8Ni0.1Ti0.1O3-δ (δ = 0.011) when compared to La0.75Sr0.25CrO3-δ (δ = 0.091), La0.75Sr0.25Cr0.5Mn0.5O3-δ (δ = 0.175) and La0.75Sr0.25Cr0.5Fe0.5O3-δ (δ = 0.148) at 1000 °C and ∼10-24 atm. Highest electrochemical performance and structural/interfacial stability is obtained for new composition La0.85Sr0.15Cr0.8Ni0.1Ti0.1O3-δ (LSCNT0.1) when mixed with 8YSZ in both oxidizing and reducing atmosphere.

  12. New Measurements of Doubly Ionized Iron Group Spectra by High Resolution Fourier Transform and Grating Spectroscopy

    NASA Technical Reports Server (NTRS)

    Smillie, D. G.; Pickering, J. C.; Blackwell-Whitehead, R. J.; Smith, Peter L.; Nave, G.

    2006-01-01

    We report new measurements of doubly ionized iron group element spectra, important in the analysis of B-type (hot) stars whose spectra they dominate. These measurements include Co III and Cr III taken with the Imperial College VUV Fourier transform (FT) spectrometer and measurements of Co III taken with the normal incidence vacuum spectrograph at NIST, below 135 nm. We report new Fe III grating spectra measurements to complement our FT spectra. Work towards transition wavelengths, energy levels and branching ratios (which, combined with lifetimes, produce oscillator strengths) for these ions is underway.

  13. New Atomic Data for Doubly Ionized Iron Group Atoms by High Resolution UV Fourier Transform Spectroscopy

    NASA Technical Reports Server (NTRS)

    Smith, Peter L.; Pickering, Juliet C.; Thorne, A. P.

    2002-01-01

    Currently available laboratory spectroscopic data of doubly ionized iron-group element were obtained about 50 years ago using spectrographs of modest dispersion, photographic plates, and eye estimates of intensities. The accuracy of the older wavelength data is about 10 mAngstroms at best, whereas wavelengths are now needed to an accuracy of 1 part in 10(exp 6) to 10(exp 7) (0.2 to 2 mAngstroms at 2000 Angstroms). The Fourier transform (FT) spectroscopy group at Imperial College, London, and collaborators at the Harvard College Observatory have used a unique VUV FT spectrometer in a program focussed on improving knowledge of spectra of many neutral and singly and doubly ionized, astrophysically important, iron group elements. Spectra of Fe II and Fe III have been recorded at UV and VUV wavelengths with signal-to-noise ratios of several hundred for the stronger lines. Wavelengths and energy levels for Fe III are an order of magnitude more accurate than previous work; analysis is close to completion. f-values for Fe II have been published.

  14. Inviscid fluid in high frequency excitation field

    NASA Technical Reports Server (NTRS)

    Zak, M.

    1984-01-01

    The influence of high frequency excitations (HFE) on a fluid is investigated. The response to these excitations is decomposed in two parts: 'slow' motion, which practically remains unchanged during the vanishingly small period tau, and 'fast' motion whose value during this period is negligible in terms of displacements, but is essential in terms of the kinetic energy. After such a decomposition the 'slow' and 'fast' motions become nonlinearly coupled by the corresponding governing equations. This coupling leads to an 'effective' potential energy which imparts some 'elastic' properties to the fluid and stabilizes laminar flows.

  15. High-spin states in doubly odd {sup 162,164}Lu

    SciTech Connect

    Cardona, M.A.; Hojman, D.; Debray, M.E.; Kreiner, A.J.; Somacal, H.; Cardona, M.A.; Hojman, D.; Debray, M.E.; Kreiner, A.J.; Somacal, H.; Davidson, J.; Davidson, M.; Davidson, J.; Hojman, D.; Kreiner, A.J.; Davidson, M.; Napoli, D.R.; Burch, R.; De Acuna, D.; Rico, J.; Bazzacco, D.; Lenzi, S.M.; Rossi Alvarez, C.; Blasi, N.; Lo Bianco, G.

    1997-08-01

    High-spin states in {sup 162}Lu and {sup 164}Lu have been studied by means of in-beam {gamma}-ray spectroscopy techniques using the multidetector array GASP. The excited states have been populated through the {sup 139}La({sup 28}Si,5n){sup 162}Lu and {sup 139}La[{sup 29(30)}Si,4(5)n]{sup 164}Lu reactions. Level schemes were constructed for both nuclei. Configurations for the rotational bands have been discussed. Alignments, band crossing frequencies, and B(M1)/B(E2) ratios have been analyzed in the framework of the cranking model. The systematic evolution of the signature inversion in the {pi}h{sub 11/2}{circle_times}{nu}i{sub 13/2} structure is reviewed. {copyright} {ital 1997} {ital The American Physical Society}

  16. Particle-number conserving analysis for the 2-quasiparticle and high-K multi-quasiparticle states in doubly-odd 174,176Lu

    NASA Astrophysics Data System (ADS)

    Li, Bing-Huan; Zhang, Zhen-Hua; Lei, Yi-An

    2013-01-01

    Two-quasiparticle bands and low-lying excited high-K four-, six-, and eight-quasiparticle bands in the doubly-odd174,176 Lu are analyzed by using the cranked shell model (CSM) with the pairing correlations treated by a particle-number conserving (PNC) method, in which the blocking effects are taken into account exactly. The proton and neutron Nilsson level schemes for174,176, Lu are taken from the adjacent odd-A Lu and Hf isotopes, which are adopted to reproduce the experimental bandhead energies of the one-quasiproton and one-quasineutron bands of these odd-A Lu and Hf nuclei, respectively. Once the quasiparticle configurations are determined, the experimental bandhead energies and the moments of inertia of these two- and multi-quasiparticle bands are well reproduced by PNC-CSM calculations. The Coriolis mixing of the low-K (K=|Ω1-Ω2|) two-quasiparticle band of the Gallagher-Moszkowski doublet with one nucleon in the Ω=1/2 orbital is analyzed.

  17. Dynamical analysis of highly excited molecular spectra

    SciTech Connect

    Kellman, M.E.

    1993-12-01

    The goal of this program is new methods for analysis of spectra and dynamics of highly excited vibrational states of molecules. In these systems, strong mode coupling and anharmonicity give rise to complicated classical dynamics, and make the simple normal modes analysis unsatisfactory. New methods of spectral analysis, pattern recognition, and assignment are sought using techniques of nonlinear dynamics including bifurcation theory, phase space classification, and quantization of phase space structures. The emphasis is chaotic systems and systems with many degrees of freedom.

  18. The decay of highly excited open strings

    NASA Technical Reports Server (NTRS)

    Mitchell, D.; Turok, N.; Wilkinson, R.; Jetzer, P.

    1988-01-01

    The decay rates of leading edge Regge trajectory states are calculated for very high level number in open bosonic string theories, ignoring tachyon final states. The optical theorem simplifies the analysis while enabling identification of the different mass level decay channels. The main result is that (in four dimensions) the greatest single channel is the emission of a single photon and a state of the next mass level down. A simple asymptotic formula for arbitrarily high level number is given for this process. Also calculated is the total decay rate exactly up to N=100. It shows little variation over this range but appears to decrease for larger N. The formalism is checked in examples and the decay rate of the first excited level calculated for open superstring theories. The calculation may also have implications for high spin meson resonances.

  19. New High-Pressure Excitations in Parahydrogen

    SciTech Connect

    Goncharov, A.F.; Hemley, R.J.; Mao, H.; Shu, J.

    1998-01-01

    Raman and infrared spectroscopy of para-H{sub 2} to pressures in excess of 200GPa and to 8K using new ultrapure synthetic diamond anvils reveals numerous new vibrational excitations in the three high-pressure phases. Highly resolved Raman-active librons indicate differences in orientational ordering between phasesII and III, including evidence for changes within phaseII. The librons in phaseIII are strongly pressure dependent and reflect a substantial increase in ordering with pressure. Multiple vibrons in all three phases (I, II, and III) are observed. The results place new bounds on predicted crystal structures and dynamics of the dense molecular solid. {copyright} {ital 1997} {ital The American Physical Society}

  20. High Harmonic Generation from Rotationally Excited Molecules

    NASA Astrophysics Data System (ADS)

    Lock, Robynne M.

    2011-12-01

    High harmonic generation (HHG) is understood through a three-step model. A strong laser field ionizes an atom or molecule. The free electron propagates in the laser field and may recombine with the atom or molecule leading to the generation of extreme ultraviolet or soft x-ray light at odd harmonics of the fundamental. Since the wavelength of the recombining electron is on the order of internuclear distances in molecules, HHG acts as a probe of molecular structure and dynamics. Conversely, control of the molecules leads to control of the properties (intensity, phase, and polarization) of the harmonic emission. Rotationally exciting molecules provides field-free molecular alignment at time intervals corresponding to fractions of the rotational period of the molecule. Alignment is necessary for understanding how the harmonic emission depends on molecular structure and alignment. Additionally, HHG acts as a probe of the rotational wavepackets. This thesis reports three experiments on HHG from rotationally excited molecules. Before we can use HHG as a probe of complex molecular dynamics or control harmonic properties through molecules, the harmonic emission from aligned, linear molecules must first be understood. To that end, the first experiment measures the intensity and phase of harmonics generated from N 2O and N2 near times of strong alignment revealing interferences during recombination. The second experiment demonstrates HHG as a sensitive probe of rotational wavepacket dynamics in CO2 and N2O, revealing new revival features not detected by any other probe. The final experiment focuses on understanding and controlling the polarization state of the harmonic emission. Generating elliptically polarized harmonics would be very useful for probing molecular and materials systems. We observe an elliptical dichroism in polarization-resolved measurements of the harmonic emission from aligned N2 and CO2 molecules, revealing evidence for electron-hole dynamics between the

  1. Spectroscopy, reaction, and photodissociation in highly vibrationally excited molecules

    SciTech Connect

    Not Available

    1991-01-01

    Highly vibrationally excited molecules often control the course of chemical reactions in the atmosphere, combustion, plasmas, and many other environments. The research described in this Progress Report uses laser excitation and interrogation techniques to study and control the dynamics of highly vibrationally excited molecules. In particular, they show that it is possible to unravel the details and influence the course of photodissociation and bimolecular reaction. The experiments use laser excitation of overtone vibrations to prepare highly vibrationally excited molecules, frequently with single quantum state resolution, and laser spectroscopy to monitor the subsequent behavior of the excited molecule. We have studied the vibrationally mediated photodissociation and the bond- and state-selected bimolecular reaction of highly vibrationally excited molecules. In the first process, one photon creates a highly excited molecule, a second photon from another laser dissociates it, and light from a third laser detects the population of individual product quantum states. This approach allows us to explore otherwise inaccessible regions of the ground and excited state potential energy surface and, by exciting to the proper regions of the surface, to control the breaking of a selected chemical bond. In the second process, the highly vibrationally excited molecule reacts with an atom formed either in a microwave discharge or by photolysis and another laser interrogates the products. We have used this approach to demonstrate mode- and bond-selected bimolecular reactions in which the initial excitation controls the subsequent chemistry. 30 refs., 8 figs.

  2. Energy expenditure determined by the doubly labeled water method in Bolivian Aymara living in a high altitude agropastoral community.

    PubMed

    Kashiwazaki, H; Dejima, Y; Orias-Rivera, J; Coward, W A

    1995-11-01

    Using the doubly labeled water method (DLW), we determined total energy expenditure (TEE) under free-living conditions in 23 rural Bolivian Aymara (males and females aged 4-65), natives of a small, high-altitude (4000-4100 m), rural agropastoral community in the Andes mountains. In the adults (18-65 y of age), mean TEEs for males and females were 11.1 +/- 1.8 MJ/24 h (range: 9.3-14.1) and 9.8 +/- 0.9 MJ/24 h (8.8-11.3). Non basal energy expenditure expressed as TEE relative to basal energy expenditure (TEE:RMR) and as the difference between TEE and RMR per unit of weight [(TEE-RMR)/wt] showed no significant sex differences. TEE:RMR in the adults (2.00 +/- 0.21) was significantly greater (P < 0.05) than that of adolescents and children (1.67 +/- 0.25), but the mean (TEE-RMR)/wt values were similar in children, adolescents, and adults. Significantly high RMR:FFM values in children and adolescents, reflecting a curvilinear relation of RMR and FFM, have enlarged the differences in TEE:RMR by age groups. When compared with other DLW studies for free-living nonobese adults, the RMR of adult Aymara subjects normalized by the ratio method (RMR:FFM) and by the regression-based method (RMR adjusted with FFM as the covariate) was not significantly different from that observed in subjects living in low altitudes. As compared to FAO/WHO/UNU (1985) recommendations, activity levels were classified as heavy for the adult females and moderate-heavy for the adult males. Energy requirements for maintaining everyday tasks in the Andean people are much higher than expected from the previous studies on food consumption. PMID:7572734

  3. Doubly Stochastic Earthquake Source Model: "Omega-Square" Spectrum and Low High-Frequency Directivity Revealed by Numerical Experiments

    NASA Astrophysics Data System (ADS)

    Gusev, A. A.

    2014-10-01

    Since its formulation in 1967-1970, the classical ω -2 model of earthquake source spectrum awaits a consistent theoretical foundation. To obtain one, stochastic elements are incorporated both into the final structure of the fault and into the mode of rupture propagation. The main components of the proposed "doubly stochastic" model are: (1) the Andrews's concept, that local stress drop over a fault is a random self-similar field; (2) the concept of rupture with running slip pulse, after Heaton; (3) the hypothesis that a rupture front is a tortuous, multiply connected ("lacy") fractal polyline that occupies a strip of finite width close to the slip-pulse width; and (4) the assumption that the propagation distance of fault-guided, mostly Rayleigh waves from a failing spot on a fault is determined by the slip-pulse width. Waveforms produced by this model are determined based on the fault asperity failure model after Das and Kostrov. Properties of the model are studied by numerical experiments. At high frequency, simulated source spectra behave as ω -2, and acceleration spectra are flat. Their level, at a given seismic moment and rms stress drop, is inversely related to the relative width of the slip pulse. When this width is relatively low, a well-defined second corner frequency (lower cutoff of acceleration spectrum) is seen. The model shows clear dependence of propagation-related directivity on frequency. Between the first and the second corner frequency, amplitude spectra are strongly enhanced for the forward direction; whereas, above the second corner frequency, directivity is significantly reduced. Still, it is not inhibited totally, suggesting incomplete incoherence of the simulated radiator at high frequencies.

  4. Doubly-excited {sup 1,3}D{sup e} resonance states of two-electron positive ions Li{sup +} and Be{sup 2+} in Debye plasmas

    SciTech Connect

    Kar, Sabyasachi; Wang, Yang; Jiang, Zishi; Li, Shuxia; Ratnavelu, K.

    2014-01-15

    We investigate the bound {sup 1,3}D states and the doubly-excited {sup 1,3}D{sup e} resonance states of two-electron positive ions Li{sup +} and Be{sup 2+} by employing correlated exponential wave functions. In the framework of the stabilization method, we are able to extract three series (2pnp, 2snd, 2pnf) of {sup 1}D{sup e} resonances and two series (2pnp, 2snd) of {sup 3}D{sup e} resonances below the N = 2 threshold. The {sup 1,3}D{sup e} resonance parameters (resonance energies and widths) for Li{sup +} and Be{sup 2+} along with the bound-excited 1s3d {sup 1,3}D state energies are reported for the first time as functions of the screening parameter. Accurate resonance energies and widths are also reported for Li{sup +} and Be{sup 2+} in vacuum. For free-atomic cases, comparisons are made with the reported results and few resonance states are reported for the first time.

  5. Convoy electron emission following ionization of highly-charged ions excited by resonant coherent excitation

    NASA Astrophysics Data System (ADS)

    Suda, S.; Nakano, Y.; Metoki, K.; Shindo, T.; Ohtsuki, S.; Azuma, T.; Hatakeyama, A.; Komaki, K.; Nakai, Y.; Takada, E.; Murakami, T.

    2012-11-01

    Projectile ionization of highly-charged Ar and Fe ions in the excited states passing relativistically fast through a thin crystalline foil was experimentally studied. We selectively controlled the population of the excited states of the projectiles, and their alignment by choosing a specific m-state through three-dimensional resonant coherent excitation technique by periodical electric fields in a crystalline. We measured energy-differential spectra of electron emission released from projectiles at zero degree. Under the resonance condition, we found an evident enhancement of the convoy electron yield, which reflects the electron momentum distribution of the initial bound state of the excited ions.

  6. Hexagonal ice transforms at high pressures and compression rates directly into "doubly metastable" ice phases.

    PubMed

    Bauer, Marion; Winkel, Katrin; Toebbens, Daniel M; Mayer, Erwin; Loerting, Thomas

    2009-12-14

    We report compression and decompression experiments of hexagonal ice in a piston cylinder setup in the temperature range of 170-220 K up to pressures of 1.6 GPa. The main focus is on establishing the effect that an increase in compression rate up to 4000 MPa/min has on the phase changes incurred at high pressures. While at low compression rates, a phase change to stable ice II takes place (in agreement with earlier comprehensive studies), we find that at higher compression rates, increasing fractions and even pure ice III forms from hexagonal ice. We show that the critical compression rate, above which mainly the metastable ice III polymorph is produced, decreases by a factor of 30 when decreasing the temperature from 220 to 170 K. At the highest rate capable with our equipment, we even find formation of an ice V fraction in the mixture, which is metastable with respect to ice II and also metastable with respect to ice III. This indicates that at increasing compression rates, progressively more metastable phases of ice grow from hexagonal ice. Since ices II, III, and V differ very much in, e.g., strength and rheological properties, we have prepared solids of very different mechanical properties just by variation in compression rate. In addition, these metastable phases have stability regions in the phase diagrams only at much higher pressures and temperatures. Therefore, we anticipate that the method of isothermal compression at low temperatures and high compression rates is a tool for the academic and industrial polymorph search with great potential. PMID:20001064

  7. Spectroscopy, reaction, and photodissociation of highly vibrationally excited molecules

    SciTech Connect

    Crim, F.F.

    1990-01-01

    This research is designed to determine the nature of highly vibrationally excited molecules, probe unimolecular reactions at the level of individual quantum states, and study the dynamics of electronic photodissociation from highly vibrationally excited states. In our experiments, pulsed laser excitation of a vibrational overtone transition prepares a highly vibrationally excited molecule and time-resolved spectroscopic detection of products monitors their subsequent decomposition. We have used this scheme to follow unimolecular reactions of large and small molecules in both room temperature gases and supersonic expansions and to investigate the role that vibrational excitation plays in electronic photodissociation dynamics. Most recently we have used the localized nature of the highly vibrationally excited states we create to selectively break bonds in photodissociation and biomolecular reactions.

  8. Concepts of Highly Excited Electronic Systems

    NASA Astrophysics Data System (ADS)

    Berakdar, Jamal

    2003-05-01

    Knowledge of the excitation characteristics of matter is decisive for the descriptions of a variety of dynamical processes, which are of significant technological interest. E.g. transport properties and the optical response are controlled by the excitation spectrum. This self-contained work is a coherent presentation of the quantum theory of correlated few-particle excitations in electronic systems. It begins with a compact resume of the quantum mechanics of single particle excitations. Particular emphasis is put on Green function methods, which offer a natural tool to unravel the relations between the physics of small and large electronic systems. The book contains explicit expressions for the Coulomb Green function of two charge particles and a generalization to three-body systems. Techniques for the many-body Green function of finite systems are introduced and some explicit calculations of the Green functions are given. Concrete examples are provided and the theories are contrasted with experimental data, when available. The second volume presents an up-to-date selection of applications of the developed concepts and a comparison with available experiments is made

  9. Doubly Distributed Transactions

    Energy Science and Technology Software Center (ESTSC)

    2014-08-25

    Doubly Distributed Transactions (D2T) offers a technique for managing operations from a set of parallel clients with a collection of distributed services. It detects and manages faults. Example code with a test harness is also provided

  10. Doubly fed induction machine

    DOEpatents

    Skeist, S. Merrill; Baker, Richard H.

    2005-10-11

    An electro-mechanical energy conversion system coupled between an energy source and an energy load including an energy converter device having a doubly fed induction machine coupled between the energy source and the energy load to convert the energy from the energy source and to transfer the converted energy to the energy load and an energy transfer multiplexer coupled to the energy converter device to control the flow of power or energy through the doubly fed induction machine.

  11. Collisional energy transfer in highly excited molecules.

    PubMed

    Houston, Paul L; Conte, Riccardo; Bowman, Joel M

    2014-09-11

    The excitation/de-excitation step in the Lindemann mechanism is investigated in detail using model development and classical trajectory studies based on a realistic potential energy surface. The model, based on a soft-sphere/line-of-centers approach and using elements of Landau-Teller theory and phase space theory, correctly predicts most aspects of the joint probability distribution P(ΔE,ΔJ) for the collisional excitation and de-excitation process in the argon-allyl system. The classical trajectories both confirm the validity of the model and provide insight into the energy transfer. The potential employed was based on a previously available ab initio intramolecular potential for the allyl fit to 97418 allyl electronic energies and an intermolecular potential fit to 286 Ar-allyl energies. Intramolecular energies were calculated at the CCSD(T)/AVTZ level of theory, while intermolecular energies were calculated at the MP2/AVTZ level of theory. Trajectories were calculated for each of four starting allyl isomers and for an initial rotational level of Ji = 0 as well as for Ji taken from a microcanonical distribution. Despite a dissimilarity in Ar-allyl potentials for fixed Ar-allyl geometries, energy transfer properties starting from four different isomers were found to be remarkably alike. A contributing factor appears to be that the orientation-averaged potentials are almost identical. The model we have developed suggests that most hydrocarbons should have similar energy transfer properties, scaled by differences in the potential offset of the atom-hydrogen interaction. Available data corroborate this suggestion. PMID:25116732

  12. Collisional quenching of highly rotationally excited HF

    NASA Astrophysics Data System (ADS)

    Yang, B.; Walker, K. M.; Forrey, R. C.; Stancil, P. C.; Balakrishnan, N.

    2015-06-01

    Context. Collisional excitation rate coefficients play an important role in the dynamics of energy transfer in the interstellar medium. In particular, accurate rotational excitation rates are needed to interpret microwave and infrared observations of the interstellar gas for nonlocal thermodynamic equilibrium line formation. Aims: Theoretical cross sections and rate coefficients for collisional deexcitation of rotationally excited HF in the vibrational ground state are reported. Methods: The quantum-mechanical close-coupling approach implemented in the nonreactive scattering code MOLSCAT was applied in the cross section and rate coefficient calculations on an accurate 2D HF-He potential energy surface. Estimates of rate coefficients for H and H2 colliders were obtained from the HF-He collisional data with a reduced-potential scaling approach. Results: The calculation of state-to-state rotational quenching cross sections for HF due to He with initial rotational levels up to j = 20 were performed for kinetic energies from 10-5 to 15 000 cm-1. State-to-state rate coefficients for temperatures between 0.1 and 3000 K are also presented. The comparison of the present results with previous work for lowly-excited rotational levels reveals significant differences. In estimating HF-H2 rate coefficients, the reduced-potential method is found to be more reliable than the standard reduced-mass approach. Conclusions: The current state-to-state rate coefficient calculations are the most comprehensive to date for HF-He collisions. We attribute the differences between previously reported data and our results to differences in the adopted interaction potential energy surfaces. The new He rate coefficients can be used in a variety of applications. The estimated H2 and H collision rates can also augment the smaller datasets previously developed for H2 and electrons. Rate coefficient tables are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130

  13. The [NeIV] Lines in High Excitation Gaseous Nebulae.

    PubMed

    Aller, L H

    1970-04-01

    The "forbidden" lines of three times ionized neon are among the most precious indicators of electron temperature and excitation. They are also predicted to be among the strongest lines observed in the far ultraviolet spectra of high excitation nebulae. PMID:16591822

  14. Possibility of synthesizing a doubly magic superheavy nucleus

    SciTech Connect

    Aritomo, Y.

    2007-02-15

    The possibility of synthesizing a doubly magic superheavy nucleus, {sup 298}114{sub 184}, is investigated on the basis of fluctuation-dissipation dynamics. In order to synthesize this nucleus, we must generate more neutron-rich compound nuclei because of the neutron emissions from excited compound nuclei. The compound nucleus {sup 304}114 has two advantages to achieving a high survival probability. First, because of low neutron separation energy and rapid cooling, the shell correction energy recovers quickly. Secondly, owing to neutron emissions, the neutron number in the nucleus approaches that of the double closed shell and the nucleus attains a large fission barrier. Because of these two effects, the survival probability of {sup 304}114 does not decrease until the excitation energy E{sup *}=50 MeV. These properties lead to a rather high evaporation residue cross section.

  15. Chemical composition of high-excitation planetaries.

    PubMed

    Aller, L H; Czyzak, S J

    1981-09-01

    Nebular spectral line intensities measured mostly in the optical region, but also in the IR and satellite UV (where possible), are used to derive plasma diagnostics and ionic concentrations n (X(i))/n(H(+)). Then, we use theoretical nebular models to represent as closely as possible certain excitation-sensitive line ratios of HeII/HeI, [OIII]/[OII], and [NeIII]/[NeV]. Also, we try to reproduce the line intensities themselves. These models are used as devices to allow for unobserved ionization stages. Although He, C, and N show significant variations among different nebulae, heavier elements such as O, and probably Ne, S, Cl, and Ar are more nearly constant, suggesting that progenitor stars underwent nuclear transformations in their interiors that affected C and N but not heavier elements. PMID:16593076

  16. Energy calculation of 2s2 1S, 2p2 1D, 3s2 1S, 3p2 1D, 3d2 1G, 4p2 1D, 4d2 1D, 4f2 1I doubly excited states using a new wave function to four terms for 2 ≤ Z ≤ 15

    NASA Astrophysics Data System (ADS)

    Sow, B.; Sow, M.; Gning, Y.; Traore, A.; Ndao, A. S.; Wague, A.

    2016-06-01

    Calculation of the energy levels of atoms and ions with 2 ≤ Z ≤ 15 are carried out in this paper using a Hyllerass approximation. The method used is one of Screen Constant by Nuclear Charge Unit to calculate the total energy of two-electron atomic systems in ground and different doubly excited states. Employing a new wave function including correlation, we were able to calculate excited states (nl)2 (n ≤ 4). The Comparison of these results with the ones of other methods shows a good agreement.

  17. Highly excited and exotic meson spectrum from dynamical lattice QCD

    SciTech Connect

    Jozef Dudek, Robert Edwards, David Richards, Christopher Thomas

    2009-12-01

    Using a new quark-field construction algorithm and a large variational basis of operators, we extract a highly excited isovector meson spectrum on dynamical anisotropic lattices. We show how carefully constructed operators can be used to identify the continuum spin of extracted states. This method allows us to extract, with confidence, excited states, states of high spin and states with exotic quantum numbers, including, for the first time, spin-four states.

  18. Raman scattering in high-{Tc} superconductors: Electronic excitations

    SciTech Connect

    Cardona, M.; Strohm, T.; Kircher, J.

    1996-12-31

    Since the discovery of the high {Tc} superconductors Raman scattering has proven to be an excellent technique to characterize them and to investigate basic physical properties relevant to the elusive mechanism responsible for their superconductivity. The authors discuss here several aspects of the technique as applied to superconductivity, including scattering by lattice vibrations, magnetic excitations, and electronic excitations, with particular emphasis on the latter, both in the normal and the superconducting state. 47 refs., 8 figs., 1 tab.

  19. Production of doubly heavy-flavored hadrons at e+e- colliders

    NASA Astrophysics Data System (ADS)

    Zheng, Xu-Chang; Chang, Chao-Hsi; Pan, Zan

    2016-02-01

    Production of the doubly heavy-flavored hadrons (Bc meson, doubly heavy baryons Ξc c , Ξb c , Ξb b , their excited states, and antiparticles of them as well) at e+e- colliders is investigated under two different approaches: LO (leading-order QCD complete calculation) and LL (leading-logarithm fragmentation calculation). The results for the production obtained by the LO and LL approaches, including the angle distributions of the produced hadrons with unpolarized and polarized incoming beams, the behaviors on the energy fraction of the produced doubly heavy-flavored hadron, and comparisons of results between the two approaches, are presented in tables and figures. Thus, characteristics of the production and uncertainties of the approaches are shown precisely, and it is concluded that only if the colliders run at the energies around the Z pole (which may be called the Z factories) and the luminosity of the colliders is as high as possible is the study of the doubly heavy-flavored hadrons completely accessible.

  20. Metastable states of highly excited heavy ions

    NASA Technical Reports Server (NTRS)

    Pegg, D. J.; Griffin, P. M.; Sellin, I. A.; Smith, W. W.; Donnally, B.

    1973-01-01

    Description of the method used and results obtained in an experimental study of the metastable states of highly stripped heavy ions, aimed at determining the lifetimes of such states by the rates of autoionization and radiation. The significance and limitations of the results presented are discussed.

  1. Determination of the nuclear level density at high excitation energy

    SciTech Connect

    Chbihi, A.; Sobotka, L.G.; Nicolis, N.G.; Sarantites, D.G.; Stracener, D.W.; Majka, Z. ); Hensley, D.C.; Beene, J.R.; Halbert, M.L. )

    1991-02-01

    Evaporation simulations are presented to illustrate the problems associated with the determination of the nuclear level density constant at high excitation energy from evaporation spectra. The methods of using either the total (whole chain) spectra or the difference (from two different initial excitation energies) spectra are discussed. Data from the study of the reaction 701 MeV {sup 28}Si+{sup 100}Mo are presented and both methods are used to extract the level density constant. We find that in order to reproduce the slopes of the light particle spectra the level density constant must have a value near 1/10{ital A}-- 1 / 11 {ital A} for excited nuclei with statistical temperatures in the range of 3.5 to 5.5 MeV. This presumes that the only parameter adjustment required to treat the decay of highly exited nuclei is the level density constant. If this is so, the shapes of the evaporation spectra imply a reduction in the level density constant from the value required to explain the decay of less highly excited nuclei, a conclusion reached by others. However, the reduced level density constant leads to an overproduction of deuterons and tritons. This suggests that a more complicated set of parameter adjustments may be required to treat the decay of highly excited nuclei.

  2. Doubly robust survival trees.

    PubMed

    Steingrimsson, Jon Arni; Diao, Liqun; Molinaro, Annette M; Strawderman, Robert L

    2016-09-10

    Estimating a patient's mortality risk is important in making treatment decisions. Survival trees are a useful tool and employ recursive partitioning to separate patients into different risk groups. Existing 'loss based' recursive partitioning procedures that would be used in the absence of censoring have previously been extended to the setting of right censored outcomes using inverse probability censoring weighted estimators of loss functions. In this paper, we propose new 'doubly robust' extensions of these loss estimators motivated by semiparametric efficiency theory for missing data that better utilize available data. Simulations and a data analysis demonstrate strong performance of the doubly robust survival trees compared with previously used methods. Copyright © 2016 John Wiley & Sons, Ltd. PMID:27037609

  3. Eucken correction in high-temperature gases with electronic excitation

    SciTech Connect

    Istomin, V. A.; Kustova, E. V. Mekhonoshina, M. A.

    2014-05-14

    In the present paper, thermal conductivity coefficient of high-temperature molecular and atomic gases with excited electronic states is studied using both the kinetic theory algorithm developed by authors earlier and the well known simple expression for the thermal conductivity coefficient proposed by Eucken and generalized by Hirschfelder. The influence of large collision diameters of excited states on the thermal conductivity is discussed. The limit of validity of the Eucken correction is evaluated on the basis of the kinetic theory calculations; an improved model suitable for air species under high-temperature conditions is proposed.

  4. Self-excited vibrational viscometer for high-viscosity sensing

    NASA Astrophysics Data System (ADS)

    Yabuno, Hiroshi; Higashino, Keiichi; Kuroda, Masaharu; Yamamoto, Yasuyuki

    2014-09-01

    A method for vibrational viscometers capable of high-viscosity measurements using self-excited oscillations is proposed and assessed both theoretically and experimentally. Such viscometers are well-known for their rapid response and miniaturization. Unlike conventional methods based on Q-value estimations obtained experimentally from the frequency response or resonance curve, we describe the use of self-excited oscillations in viscosity measurements using positive velocity feedback control without relying on the frequency response curve. Such measurements become possible even for high viscosities where the peak of the frequency response curve is ambiguous or does not exist, i.e., the Q-value cannot be estimated from such curves. Furthermore, the validity of the proposed method is experimentally tested using a prototype self-excited viscometer. Downsized oscillators such as micro- or nanoscale cantilevers can be self-excited following a straightforward application of the method. They are expected to enable not only localized monitoring of changes in high viscosity with time but also spatial high-viscosity measurements by the distributed arrangement of the devices.

  5. Fluctuations, Saturation, and Diffractive Excitation in High Energy Collisions

    SciTech Connect

    Flensburg, Christoffer

    2011-07-15

    Diffractive excitation is usually described by the Good-Walker formalism for low masses, and by the triple-Regge formalism for high masses. In the Good-Walker formalism the cross section is determined by the fluctuations in the interaction. By taking the fluctuations in the BFKL ladder into account, it is possible to describe both low and high mass excitation in the Good-Walker formalism. In high energy pp collisions the fluctuations are strongly suppressed by saturation, which implies that pomeron exchange does not factorise between DIS and pp collisions. The Dipole Cascade Model reproduces the expected triple-Regge form for the bare pomeron, and the triple-pomeron coupling is estimated.

  6. Elemental abundances in high-excitation planetary nebulae

    NASA Technical Reports Server (NTRS)

    Marionni, P. A.; Harrington, J. P.

    1981-01-01

    The IUE satellite was used to obtain low dispersion spectra of the high excitation planetary nebulae IC 351, IC 2003, NGC 2022, IC 2165, NGC 2440, Hu 1-2, and IC 5217. Numerical modeling was undertaken to determine the chemical composition of these objects with particular emphasis on obtaining elemental carbon and nitrogen abundances. Large variations in the C/N ratio from object to object are suggested.

  7. Highly excited and exotic meson spectroscopy from lattice QCD

    SciTech Connect

    Christopher Thomas

    2011-05-01

    I will discuss recent progress in extracting highly excited and exotic meson spectra using lattice QCD. New results in the light meson sector will be presented, where a combination of techniques have enabled us to confidently identify the spin of extracted states. Highlights include many states with exotic quantum numbers and, for the first time in a lattice QCD calculation, spin-four states. I will conclude with comments on future prospects.

  8. Observation of interference effects via four-photon excitation of highly excited Rydberg states in thermal cesium vapor

    NASA Astrophysics Data System (ADS)

    Kondo, Jorge M.; Šibalić, Nikola; Guttridge, Alexander; Wade, Christopher G.; De Melo, Natalia R.; Adams, Charles S.; Weatherill, Kevin J.

    2015-12-01

    We report on the observation of electromagnetically induced transparency (EIT) and absorption (EIA) of highly excited Rydberg states in thermal Cs vapor using a four-step excitation scheme. The advantage of this four-step scheme is that the final transition to the Rydberg state has a large dipole moment and one can achieve similar Rabi frequencies to two- or three-step excitation schemes using two orders of magnitude less laser power. This scheme enables new applications such as dephasing free Rydberg excitation. The observed lineshapes are in good agreement with simulations based on multilevel optical Bloch equations.

  9. High-Frequency Stimulation of Excitable Cells and Networks

    PubMed Central

    Weinberg, Seth H.

    2013-01-01

    High-frequency (HF) stimulation has been shown to block conduction in excitable cells including neurons and cardiac myocytes. However, the precise mechanisms underlying conduction block are unclear. Using a multi-scale method, the influence of HF stimulation is investigated in the simplified FitzhHugh-Nagumo and biophysically-detailed Hodgkin-Huxley models. In both models, HF stimulation alters the amplitude and frequency of repetitive firing in response to a constant applied current and increases the threshold to evoke a single action potential in response to a brief applied current pulse. Further, the excitable cells cannot evoke a single action potential or fire repetitively above critical values for the HF stimulation amplitude. Analytical expressions for the critical values and thresholds are determined in the FitzHugh-Nagumo model. In the Hodgkin-Huxley model, it is shown that HF stimulation alters the dynamics of ionic current gating, shifting the steady-state activation, inactivation, and time constant curves, suggesting several possible mechanisms for conduction block. Finally, we demonstrate that HF stimulation of a network of neurons reduces the electrical activity firing rate, increases network synchronization, and for a sufficiently large HF stimulation, leads to complete electrical quiescence. In this study, we demonstrate a novel approach to investigate HF stimulation in biophysically-detailed ionic models of excitable cells, demonstrate possible mechanisms for HF stimulation conduction block in neurons, and provide insight into the influence of HF stimulation on neural networks. PMID:24278435

  10. High frame rate photoacoustic computed tomography using coded excitation

    NASA Astrophysics Data System (ADS)

    Azuma, Masataka; Zhang, Haichong K.; Kondo, Kengo; Namita, Takeshi; Yamakawa, Makoto; Shiina, Tsuyoshi

    2015-03-01

    Photoacoustic Computed Tomography (PACT) records signals from a wide range of angles to achieve uniform, highresolution images. A high-power laser is generally used for PACT, but the long acquisition time with a single probe is a problem due to the low pulse-repetition frequency (PRF). For PACT, this degrades image resolution and contrast because it is hard to scan with a small step interval. Moreover, in vivo measurement requires a fast image acquisition system to avoid motion artifacts. The problem can be resolved by using a high PRF laser, which provides only weak energy. Averaging measured signals many times can mitigate the low signal-to-noise issue, but the PRF is restricted by the acoustic time of flight, so this is a new source of measurement time increase. Here, we present the coded-excitation approach, which we previously proposed for linear scanning, to increase the PACT frame rate. Coded excitation irradiates temporally encoded pulses and enhances the signal amplitude through decoding. The PRF is thus not restricted to acoustic time of flight. Consequently, acquisition time can be shortened by increasing PRF, and the SNR increases for the same measurement time. To validate the proposed idea, we conducted experiments using a high PRF laser with a revolving motor and compared the performance of coded excitation to that of averaging. Results demonstrated that the contamination of a signal acquired from different angles was negligible, and that the scanning pitch was remarkably improved because the start point of decoding can be set in any code in the periodic sequence.

  11. Unexpected doubly-magic nucleus.

    SciTech Connect

    Janssens, R. V. F.; Physics

    2009-01-01

    Nuclei with a 'magic' number of both protons and neutrons, dubbed doubly magic, are particularly stable. The oxygen isotope {sup 24}O has been found to be one such nucleus - yet it lies just at the limit of stability.

  12. The remarkably high excitation planetary nebula GC 6537.

    PubMed

    Aller, L H; Hung, S; Feibelman, W A

    1999-05-11

    NGC 6537 is an unusually high excitation point symmetric planetary nebula with a rich spectrum. Its kinematical structures are of special interest. We are here primarily concerned with the high resolution spectrum as revealed by the Hamilton echelle Spectrograph at Lick Observatory (resolution approximately 0.2 A) and supplemented by UV and near-UV data. These extensive data permit a determination of interstellar extinction, plasma diagnostics, and ionic concentrations. The photoionization models that have been used successfully for many planetary nebulae are not entirely satisfactory here. The plasma electron temperature of a photoionization model cannot much exceed 20,000 K, but plasma diagnostics show that regions emitting radiation of highly ionized atoms such as [NeIV] and [NeV] are much hotter, showing that shock excitation must be important, as suggested by the remarkable kinematics of this object. Hence, instead of employing a strict photoionization model, we are guided by the nebular diagnostics, which reveal how electron temperature varies with ionization potential and accommodates density effects. The predictions of the photoionization model may be useful in estimating ionization correction factor. In effect, we have estimated the chemical composition by using both photoionization and shock considerations. PMID:10318889

  13. High levels of isotope elimination improve precision and allow individual-based measurements of metabolic rates in animals using the doubly labeled water method

    PubMed Central

    Shirai, Masaki; Niizuma, Yasuaki; Yamamoto, Maki; Oda, Emiko; Ebine, Naoyuki; Oka, Nariko; Yoda, Ken

    2015-01-01

    Doubly labeled water (DLW) can be used to measure energy expenditure in free-ranging animals, but questions have been raised about its accuracy in different species or contexts. We investigated whether differences in the extent of isotope elimination affects the precision and accuracy of the DLW method, which can vary according to the experimental design or metabolic rate of the species. Estimated total energy expenditure by the DLW method (TEEdlw) was compared with actual total energy expenditure simultaneously measured via respirometry (TEEresp) in streaked shearwaters Calonectris leucomelas, a pelagic seabird. Subjects were divided into three groups with different experimental conditions: at rest on the ground for 24 h (Group A) or for 48 h (Group B), and at rest on the water for 24 h (Group C). TEEdlw in Group A matched TEEresp, whereas there was an overestimation of TEEdlw in both Groups B and C compared with TEEresp. However, compared with Group A, TEEdlw in Groups B and C had reduced the isotopic analytical variability and thus higher precision. The best regression model (TEEdlw = 1.37 TEEresp − 14.12) showed a high correlation (R2 = 0.82) between TEEdlw and TEEresp and allows a correction factor for field metabolic rates in streaked shearwaters. Our results demonstrate that the commonly made assumption that the DLW method is not appropriate for individual-based estimates may be incorrect in certain circumstances. Although a correction factor may be necessary when using the DLW method to estimate metabolic rate, greater levels of isotope eliminations provides DLW estimates with high precision, which can adequately represent relative individual estimates. Nevertheless, the DLW method, should be used with caution when characterizing interspecies difference of energy expenditures. PMID:26611463

  14. Doubly-Amphiphilic Poly(2-oxazoline)s as High-Capacity Delivery Systems for Hydrophobic Drugs

    PubMed Central

    Schulz, Anita; Roques, Caroline; Li, Shu; Bronich, Tatiana K.; Batrakova, Elena V.; Jordan, Rainer

    2010-01-01

    Solubilization of highly hydrophobic drugs with carriers that are non-toxic, non-immunogenic and well-defined remains a major obstacle in pharmaceutical sciences. Well defined amphiphilic di- and triblock copolymers based on poly(2-oxazolines) were prepared and used for the solubilization of Paclitaxel (PTX) and other water-insoluble drugs. Probing the polymer micelles in water with the fluorescence probe pyrene, an unusual high polar microenvironment of the probe was observed. This coincides with an extraordinary large loading capacity for PTX of 45 wt.% active drug in the formulation as well as high water solubility of the resulting formulation. Physicochemical properties of the formulations, ease of preparation and stability upon lyophilization, low toxicity and immunogenicity suggest that poly(2-oxazoline)s are promising candidates for the delivery of highly challenging drugs. Furthermore, we demonstrate that PTX is fully active and provides superior tumor inhibition as compared to the commercial micellar formulation. PMID:20346493

  15. Excitation and Ionisation dynamics in high-frequency plasmas

    NASA Astrophysics Data System (ADS)

    O'Connell, D.

    2008-07-01

    Non-thermal low temperature plasmas are widely used for technological applications. Increased demands on plasma technology have resulted in the development of various discharge concepts based on different power coupling mechanisms. Despite this, power dissipation mechanisms in these discharges are not yet fully understood. Of particular interest are low pressure radio-frequency (rf) discharges. The limited understanding of these discharges is predominantly due to the complexity of the underlying mechanisms and difficult diagnostic access to important parameters. Optical measurements are a powerful diagnostic tool offering high spatial and temporal resolution. Optical emission spectroscopy (OES) provides non-intrusive access, to the physics of the plasma, with comparatively simple experimental requirements. Improved advances in technology and modern diagnostics now allow deeper insight into fundamental mechanisms. In low pressure rf discharges insight into the electron dynamics within the rf cycle can yield vital information. This requires high temporal resolution on a nano-second time scale. The optical emission from rf discharges exhibits temporal variations within the rf cycle. These variations are particularly strong, in for example capacitively coupled plasmas (CCPs), but also easily observable in inductively coupled plasmas (ICPs), and can be exploited for insight into power dissipation. Interesting kinetic and non-linear coupling effects are revealed in capacitive systems. The electron dynamics exhibits a complex spatio-temporal structure. Excitation and ionisation, and, therefore, plasma sustainment is dominated through directed energetic electrons created through the dynamics of the plasma boundary sheath. In the relatively simple case of an asymmetric capacitively coupled rf plasma the complexity of the power dissipation is exposed and various mode transitions can be clearly observed and investigated. At higher pressure secondary electrons dominate the

  16. Radiance limits of ceramic phosphors under high excitation fluxes

    NASA Astrophysics Data System (ADS)

    Lenef, Alan; Kelso, John; Zheng, Yi; Tchoul, Maxim

    2013-09-01

    Ceramic phosphors, excited by high radiance pump sources, offer considerable potential for high radiance conversion. Interestingly, thermodynamic arguments suggest that the radiance of the luminescent spot can even exceed that of the incoming light source. In practice, however, thermal quenching and (non-thermal) optical saturation limit the maximum attainable radiance of the luminescent source. We present experimental data for Ce:YAG and Ce:GdYAG ceramics in which these limits have been investigated. High excitation fluxes are achieved using laser pumping. Optical pumping intensities exceeding 100W/mm2 have been shown to produce only modest efficiency depreciation at low overall pump powers because of the short Ce3+ lifetime, although additional limitations exist. When pump powers are higher, heat-transfer bottlenecks within the ceramic and heat-sink interfaces limit maximum pump intensities. We find that surface temperatures of these laser-pumped ceramics can reach well over 150°C, causing thermal-quenching losses. We also find that in some cases, the loss of quantum efficiency with increasing temperature can cause a thermal run-away effect, resulting in a rapid loss in converted light, possibly over-heating the sample or surrounding structures. While one can still obtain radiances on the order of many W/mm2/sr, temperature quenching effects ultimately limit converted light radiance. Finally, we use the diffusion-approximation radiation transport models and rate equation models to simulate some of these nonlinear optical pumping and heating effects in high-scattering ceramics.

  17. Experimental oscillator strengths of highly excited levels of Mo II

    NASA Astrophysics Data System (ADS)

    Aragón, C.; Aguilera, J. A.; Ortiz, M.; Mayo-García, R.

    2016-05-01

    Measurements of 161 oscillator strengths arising from highly excited levels of Mo II are presented, 148 of which are obtained for the first time. These results extend the previous ones already published on lower excited levels of Mo II. A laser-induced plasma generated from a fused glass sample prepared from molybdenum oxide with a Mo atomic concentration of 0.1% was used to obtain the presented radiative parameters via laser-induced breakdown spectroscopy. Measurements were carried out with an electron density of (2.5 ± 0.1) · 1017 cm‑3 and an electron temperature of 14 400 ± 200 K as the plasma evolved in air at atmospheric pressure. As a consequence, an optically thin plasma and a local thermodynamic equilibrium environment were then present in the measurements. In order to put on an absolute scale the relative intensities, both the combination of branching fractions with measured lifetimes and the comparison of well-known lines using the plasma temperature were carried out. Also, the new results are compared with previously theoretical and obtained experimental values wherever possible.

  18. A Study of Power Systems Stability Enhancement Effects by Excitation Control of Superconducting Generator with High Response Excitation based on Detailed Excitation Circuit Model

    NASA Astrophysics Data System (ADS)

    Wu, Guohong; Shirato, Hideyuki

    SCG (Superconducting Generator) has a superconducting field winding, which leads to many advantages such as small size, high generation efficiency, low impedance, and so on, and be considered as one of the candidates to meet the needs of high stability and high efficiency in the future power system networks. SCG with high response excitation is especially expected to be able to enhance the transient stability of power system by its SMES (Superconducting Magnetic Energy System) effect. The SMES effect of SCG is recognized that its behaviors are dominated by the structures and controls of its excitation system. For this reason, in order to verify exactly how the SMES effect of SCG influences on the power system stability, the electrical circuits of SCG high response excitation are modeled in detail for conducting digital simulation, and its influence on excitation voltage and active power output of SCG are discussed as well. The simulation results with a typical one machine - infinite bus power system model shows that the SMES effect can be certainly obtained when its exciting power is supplied from SCG terminal bus and may considerably lead to an improvement of power system transient stability.

  19. High-flux hard X-ray microbeam using a single-bounce capillary with doubly focused undulator beam

    PubMed Central

    Barrea, Raul A.; Huang, Rong; Cornaby, Sterling; Bilderback, Donald H.; Irving, Thomas C.

    2009-01-01

    A pre-focused X-ray beam at 12 keV and 9 keV has been used to illuminate a single-bounce capillary in order to generate a high-flux X-ray microbeam. The BioCAT undulator X-ray beamline 18ID at the Advanced Photon Source was used to generate the pre-focused beam containing 1.2 × 1013 photons s−1 using a sagittal-focusing double-crystal monochromator and a bimorph mirror. The capillary entrance was aligned with the focal point of the pre-focused beam in order to accept the full flux of the undulator beam. Two alignment configurations were tested: (i) where the center of the capillary was aligned with the pre-focused beam (‘in-line’) and (ii) where one side of the capillary was aligned with the beam (‘off-line’). The latter arrangement delivered more flux (3.3 × 1012 photons s−1) and smaller spot sizes (≤10 µm FWHM in both directions) for a photon flux density of 4.2 × 1010 photons s−1 µm−2. The combination of the beamline main optics with a large-working-distance (approximately 24 mm) capillary used in this experiment makes it suitable for many microprobe fluorescence applications that require a micrometer-size X-ray beam and high flux density. These features are advantageous for biological samples, where typical metal concentrations are in the range of a few ng cm−2. Micro-XANES experiments are also feasible using this combined optical arrangement. PMID:19096178

  20. High-flux hard X-ray microbeam using a single-bounce capillary with doubly focused undulator beam

    SciTech Connect

    Barrea, Raul A.; Huang, Rong; Cornaby, Sterling; Bilderback, Donald H.; Irving, Thomas C.

    2009-01-15

    A pre-focused X-ray beam at 12 keV and 9 keV has been used to illuminate a single-bounce capillary in order to generate a high-flux X-ray microbeam. The BioCAT undulator X-ray beamline 18ID at the Advanced Photon Source was used to generate the pre-focused beam containing 1.2 x 10{sup 13} photons s{sup -1} using a sagittal-focusing double-crystal monochromator and a bimorph mirror. The capillary entrance was aligned with the focal point of the pre-focused beam in order to accept the full flux of the undulator beam. Two alignment configurations were tested: (i) where the center of the capillary was aligned with the pre-focused beam ('in-line') and (ii) where one side of the capillary was aligned with the beam ('off-line'). The latter arrangement delivered more flux (3.3 x 10{sup 12} photons s{sup -1}) and smaller spot sizes ({le}10 {micro}m FWHM in both directions) for a photon flux density of 4.2 x 10{sup 10} photons s{sup -1} {micro}m{sup -2}. The combination of the beamline main optics with a large-working-distance (approximately 24 mm) capillary used in this experiment makes it suitable for many microprobe fluorescence applications that require a micrometer-size X-ray beam and high flux density. These features are advantageous for biological samples, where typical metal concentrations are in the range of a few ng cm{sup -2}. Micro-XANES experiments are also feasible using this combined optical arrangement.

  1. High-flux hard X-ray microbeam using a single-bounce capillary with doubly focused undulator beam.

    PubMed

    Barrea, Raul A; Huang, Rong; Cornaby, Sterling; Bilderback, Donald H; Irving, Thomas C

    2009-01-01

    A pre-focused X-ray beam at 12 keV and 9 keV has been used to illuminate a single-bounce capillary in order to generate a high-flux X-ray microbeam. The BioCAT undulator X-ray beamline 18ID at the Advanced Photon Source was used to generate the pre-focused beam containing 1.2 x 10(13) photons s(-1) using a sagittal-focusing double-crystal monochromator and a bimorph mirror. The capillary entrance was aligned with the focal point of the pre-focused beam in order to accept the full flux of the undulator beam. Two alignment configurations were tested: (i) where the center of the capillary was aligned with the pre-focused beam (;in-line') and (ii) where one side of the capillary was aligned with the beam (;off-line'). The latter arrangement delivered more flux (3.3 x 10(12) photons s(-1)) and smaller spot sizes (< or =10 microm FWHM in both directions) for a photon flux density of 4.2 x 10(10) photons s(-1) microm(-2). The combination of the beamline main optics with a large-working-distance (approximately 24 mm) capillary used in this experiment makes it suitable for many microprobe fluorescence applications that require a micrometer-size X-ray beam and high flux density. These features are advantageous for biological samples, where typical metal concentrations are in the range of a few ng cm(-2). Micro-XANES experiments are also feasible using this combined optical arrangement. PMID:19096178

  2. Doubly charmful baryonic B decays

    SciTech Connect

    Cheng, H.-Y.; Chua, C.-K.; Tsai, S.-Y.

    2006-04-01

    There are two apparent puzzles connected with the two-body and three-body doubly charmed baryonic B decays. First, earlier calculations based on QCD sum rules or the diquark model predict B(B{sup 0}{yields}{xi}{sub c}{sup +}{lambda}{sub c}{sup -}){approx_equal}B(B{sup 0}{yields}B{sub c}N), while experimentally the former has a rate 2 orders of magnitude larger than the latter. Second, a naive estimate of the branching ratio O(10{sup -9}) for the color-suppressed three-body decay B{yields}{lambda}{sub c}{sup +}{lambda}{sub c}{sup -}K, which is highly suppressed by phase space, is too small by 5 to 6 orders of magnitude compared to the experiment. We show that the great suppression for the {lambda}{sub c}{sup +}{lambda}{sub c}{sup -}K production can be alleviated provided that there exists a narrow hidden charm bound state with a mass near the {lambda}{sub c}{lambda}{sub c} threshold. This new state that couples strongly to the charmed baryon pair can be searched for in B decays and in pp collisions by studying the mass spectrum of D{sup (*)}D{sup (*)} or {lambda}{sub c}{lambda}{sub c}. The doubly charmful decay B{yields}{xi}{sub c}{lambda}{sub c} has a configuration more favorable than the singly charmful one such as B{sup 0}{yields}{lambda}{sub c}p since no hard gluon is needed to produce the energetic {xi}{sub c}{lambda}{sub c} pair in the former decay, while two hard gluons are needed for the latter process. Assuming that a soft qq quark pair is produced through the {sigma} and {pi} meson exchanges in the configuration for B{yields}{xi}{sub c}{lambda}{sub c}, it is found that its branching ratio is of order 10{sup -3}, in agreement with the experiment.

  3. Doubly robust and efficient estimators for heteroscedastic partially linear single-index models allowing high dimensional covariates

    PubMed Central

    Ma, Yanyuan; Zhu, Liping

    2013-01-01

    Summary We study the heteroscedastic partially linear single-index model with an unspecified error variance function, which allows for high dimensional covariates in both the linear and the single-index components of the mean function. We propose a class of consistent estimators of the parameters by using a proper weighting strategy. An interesting finding is that the linearity condition which is widely assumed in the dimension reduction literature is not necessary for methodological or theoretical development: it contributes only to the simplification of non-optimal consistent estimation. We also find that the performance of the usual weighted least square type of estimators deteriorates when the non-parametric component is badly estimated. However, estimators in our family automatically provide protection against such deterioration, in that the consistency can be achieved even if the baseline non-parametric function is completely misspecified. We further show that the most efficient estimator is a member of this family and can be easily obtained by using non-parametric estimation. Properties of the estimators proposed are presented through theoretical illustration and numerical simulations. An example on gender discrimination is used to demonstrate and to compare the practical performance of the estimators. PMID:23970823

  4. High-intensity xenon pulse light source for fluorescence excitation

    NASA Astrophysics Data System (ADS)

    Miyamoto, Makoto; Ueno, Kazuo

    1997-05-01

    A newly developed 60W xenon flash lamp, L6604 and L6605, achieves the goals of longer operating life, higher output, and improved light stability. It operates at 2 Joules per flash input energy with approximately a 4 microsecond flash duration. The stability achieved is 2-3 percent peak-to-peak during a lifetime of 5 X 10e7 flashes, which is almost double that of conventional xenon flash lamps. This newly developed xenon flashlamp should serve as an excellent light source for analytical cytology and other fluorescence instruments. It can function as a high output, stable excitation light source for conventional fluorescence or delayed luminescence with a CCD. Besides providing powerful and stable illumination for absorption analysis of cells on slides, this lamp eliminates the optical artifacts associated with vibration of the stage which often limit throughput. This paper will describe in detail performance improvements obtained from this newly developed xenon flash lamp.

  5. Electron impact collision strengths for excitation of highly charged ions

    SciTech Connect

    Sampson, D.H. . Dept. of Astronomy and Astrophysics)

    1990-08-20

    The principle task given us by the Lawrence Livermore National Laboratory (LLNL) to perform under Subcontract 6181405 was to develop a method and corresponding computer programs to make very rapid, yet accurate, fully relativistic and quasirelativistic calculations of cross sections or collision strengths for electron impact excitation of highly charged ions with any value for the nuclear charge number Z. Also while this major code development was being done we were asked to calculate cross sections of interest using our previous rapid, more approximate codes, which used hydrogenic basis functions and screening constants with both the electron-electron Coulomb interaction and relativistic interactions included by perturbation theory. We were also asked to determine the branching ratio for ionization to various final states in complex cases, where two or more states corresponding to the final configuration of the ion were possible.

  6. High resolution fluorescent bio-imaging with electron beam excitation.

    PubMed

    Kawata, Yoshimasa; Nawa, Yasunori; Inami, Wataru

    2014-11-01

    We have developed electron beam excitation assisted (EXA) optical microscope[1-3], and demonstrated its resolution higher than 50 nm. In the microscope, a light source in a few nanometers size is excited by focused electron beam in a luminescent film. The microscope makes it possible to observe dynamic behavior of living biological specimens in various surroundings, such as air or liquids. Scan speed of the nanometric light source is faster than that in conventional near-field scanning optical microscopes. The microscope enables to observe optical constants such as absorption, refractive index, polarization, and their dynamic behavior on a nanometric scale. The microscope opens new microscopy applications in nano-technology and nano-science.Figure 1(a) shows schematic diagram of the proposed EXA microscope. An electron beam is focused on a luminescent film. A specimen is put on the luminescent film directly. The inset in Fig. 1(a) shows magnified image of the luminescent film and the specimen. Nanometric light source is excited in the luminescent film by the focused electron beam. The nanometric light source illuminates the specimen, and the scattered or transmitted radiation is detected with a photomultiplier tube (PMT). The light source is scanned by scanning of the focused electron beam in order to construct on image. Figure 1(b) shows a luminescence image of the cells acquired with the EXA microscope, and Fig. 1(c) shows a phase contrast microscope image. Cells were observed in culture solution without any treatments, such as fixation and drying. The shape of each cell was clearly recognized and some bright spots were observed in cells. We believe that the bright spots indicated with arrows were auto-fluorescence of intracellular granules and light- grey regions were auto-fluorescence of cell membranes. It is clearly demonstrated that the EXA microscope is useful tool for observation of living biological cells in physiological conditions.jmicro;63/suppl_1/i

  7. Spectroscopy, reaction, and photodissociation in highly vibrationally excited molecules. Technical progress report

    SciTech Connect

    Not Available

    1991-12-31

    Highly vibrationally excited molecules often control the course of chemical reactions in the atmosphere, combustion, plasmas, and many other environments. The research described in this Progress Report uses laser excitation and interrogation techniques to study and control the dynamics of highly vibrationally excited molecules. In particular, they show that it is possible to unravel the details and influence the course of photodissociation and bimolecular reaction. The experiments use laser excitation of overtone vibrations to prepare highly vibrationally excited molecules, frequently with single quantum state resolution, and laser spectroscopy to monitor the subsequent behavior of the excited molecule. We have studied the vibrationally mediated photodissociation and the bond- and state-selected bimolecular reaction of highly vibrationally excited molecules. In the first process, one photon creates a highly excited molecule, a second photon from another laser dissociates it, and light from a third laser detects the population of individual product quantum states. This approach allows us to explore otherwise inaccessible regions of the ground and excited state potential energy surface and, by exciting to the proper regions of the surface, to control the breaking of a selected chemical bond. In the second process, the highly vibrationally excited molecule reacts with an atom formed either in a microwave discharge or by photolysis and another laser interrogates the products. We have used this approach to demonstrate mode- and bond-selected bimolecular reactions in which the initial excitation controls the subsequent chemistry. 30 refs., 8 figs.

  8. High temperature electronic excitation and ionization rates in gases

    NASA Technical Reports Server (NTRS)

    Hansen, Frederick

    1991-01-01

    The relaxation times for electronic excitation due to electron bombardment of atoms was found to be quite short, so that electron kinetic temperature (T sub e) and the electron excitation temperature (T asterisk) should equilibrate quickly whenever electrons are present. However, once equilibrium has been achieved, further energy to the excited electronic states and to the kinetic energy of free electrons must be fed in by collisions with heavy particles that cause vibrational and electronic state transitions. The rate coefficients for excitation of electronic states produced by heavy particle collision have not been well known. However, a relatively simple semi-classical theory has been developed here which is analytic up to the final integration over a Boltzmann distribution of collision energies; this integral can then be evaluated numerically by quadrature. Once the rate coefficients have been determined, the relaxation of electronic excitation energy can be evaluated and compared with the relaxation rates of vibrational excitation. Then the relative importance of these two factors, electronic excitation and vibrational excitation by heavy particle collision, on the transfer of energy to free electron motion, can be assessed.

  9. Subwavelength acoustic focusing by surface-wave-resonance enhanced transmission in doubly negative acoustic metamaterials

    SciTech Connect

    Zhou, Xiaoming; Badreddine Assouar, M. Oudich, Mourad

    2014-11-21

    We present analytical and numerical analyses of a yet unseen lensing paradigm that is based on a solid metamaterial slab in which the wave excitation source is attached. We propose and demonstrate sub-diffraction-limited acoustic focusing induced by surface resonant states in doubly negative metamaterials. The enhancement of evanescent waves across the metamaterial slab produced by their resonant coupling to surface waves is evidenced and quantitatively determined. The effect of metamaterial parameters on surface states, transmission, and wavenumber bandwidth is clearly identified. Based on this concept consisting of a wave source attached on the metamaterial, a high resolution of λ/28.4 is obtained with the optimum effective physical parameters, opening then an exciting way to design acoustic metamaterials for ultrasonic focused imaging.

  10. Ionization of highly excited helium atoms in an electric field

    SciTech Connect

    van de Water, W.; Mariani, D.R.; Koch, P.M.

    1984-11-01

    We present detailed measurements of ionization of highly excited triplet helium atoms in a static electric field. The atoms were prepared in states with energy E close to the saddle-point threshold E = -2(F(a.u.))/sup 1/2/. The electric field F was sufficiently strong for the states to be characterized by total spin S and absolute value of the magnetic quantum number M/sub L/. For M/sub L/ = 0 states the experiments measured ionization properties of adiabatic states. In another case, Vertical BarM/sub L/Vertical Bar = 2, they predominantly measured those of diabatic states. In both cases the ionization rate was found to be a highly nonmonotonic function of the field strength. The observations are analyzed in terms of a theory of the helium density of states in an electric field. A companion paper (D. A. Harmin, Phys. Rev. A 30, 2413 (1984)) develops in detail the general theory, which uses quantum defects to parametrize the effect of the core interaction. The agreement between measured and calculated ionization curves is good, indicating that the field ionization of a nonhydrogenic atom can now be understood in a detailed, quantitative, and predictive sense.

  11. Properties of Shell-Model Wavefunctions at High Excitation Energies

    NASA Astrophysics Data System (ADS)

    Frazier, Njema Jioni

    Within the framework of the nuclear shell model with a realistic residual hamiltonian one can obtain the exact solution of the many-body problem. This makes it possible to study the interrelation between regular and chaotic features of dynamics in a generic many-body system with strong interaction. As an important application, we analyse the fragmentation of simple configurations as a function of excitation energy and interaction strength and examine the transition strengths induced by simple operators as a function of excitation energy. The analysis is performed for two systems; that of 12 valence particles in the sd-shell, or 28Si, and that of 8 valence particles in the sd-shell, or 24Mg. For the system of 12 valence particles in the sd-shell, we examine the fragmentation of shell-model basis states. For the system of 8 valence nucleons in the sd-shell, we examine the fragmentation associated with single-nucleon transfer and Gamow-Teller transitions. For the fragmentation of basis states, we use our statistics to establish the generic shape of the strength function distribution in the region of strong mixing. For the realistic interaction, the strength function distribution is close to Gaussian in the central part of the energy spectra. The width of the distribution is larger than predicted by Fermi's golden rule (4). We then take this one step further and examine the strength distributions associated with the one-nucleon transfer operator, aλ†, and the Gamow-Teller (GT) operator, Σλλ'(σμ τ±) λλ'aλ†a λ'. The spectroscopic factor, which is proportional to the square of the matrix element for the aλ† operator, is the simplest quantity used in predicting experimental observables. In our discussion of Gamow-Teller transitions, we examine both the GT strength function distribution and the values of total strength B(GT). For all the cases we examine, we take advantage of the reliability of our model for low-lying levels and our statistics to explore

  12. Excitation and ionization of highly charged ions by electron impact

    SciTech Connect

    Sampson, D.H.

    1989-11-15

    Two approaches for very rapid calculation of atomic data for high temperature plasma modeling have been developed. The first uses hydrogenic basis states and has been developed and applied in many papers discussed in previous progress reports. Hence, it is only briefly discussed here. The second is a very rapid, yet accurate, fully relativistic approach that has been developed over the past two or three years. It is described in more detail. Recently it has been applied to large scale production of atomic data. Specifically, it has been used to calculate relativistic distorted wave collision strengths and oscillator strengths for the following: all transitions from the ground level to the n=3 and 4 excited levels in the 71 Neon-like ions with nuclear charge number Z in the range 22 {le} Z {le} 92; all transitions among the 2s{sub {1/2}}, 2p{sub {1/2}} and 2p{sub 3/2} levels and from them to all nlj levels with n=3,4 and 5 in the 85 Li-like ions with 8 {le} Z {le} 92; all transitions among the 3s{sub {1/2}}, 3p{sub 3/2}, 3d{sub 3/2} and 3d{sub 5/2} levels and from them to all nlj levels with n=4 and 5 in the 71 Na-like ions with 22 {le} Z {le} 92; and all transitions among 4s{sub {1/2}}, 4p{sub {1/2}}, 4p{sub 3/2}, 4d{sub 3/2}, 4d{sub 5/2}, 4f{sub 5/2} and 4f{sub 7/2} levels and from them to all nlj levels with n=5 in the 33 Cu-like ions with 60 {le} Z {le} 92. Also the program has been extended to give cross-sections for excitation to specific magnetic sublevels of the target ion by an electron beam and very recently it has been extended to give relativistic distorted wave cross sections for ionization of highly charged ions by electron impact.

  13. Brushless exciters using a high temperature superconducting field winding

    DOEpatents

    Garces, Luis Jose; Delmerico, Robert William; Jansen, Patrick Lee; Parslow, John Harold; Sanderson, Harold Copeland; Sinha, Gautam

    2008-03-18

    A brushless exciter for a synchronous generator or motor generally includes a stator and a rotor rotatably disposed within the stator. The rotor has a field winding and a voltage rectifying bridge circuit connected in parallel to the field winding. A plurality of firing circuits are connected the voltage rectifying bridge circuit. The firing circuit is configured to fire a signal at an angle of less than 90.degree. or at an angle greater than 90.degree.. The voltage rectifying bridge circuit rectifies the AC voltage to excite or de-excite the field winding.

  14. Collective, stochastic and nonequilibrium behavior of highly excited hadronic matter

    SciTech Connect

    Carruthers, P.

    1983-01-01

    We discuss selected problems concerning the dynamic and stochasticc behavior of highly excited matter, particularly the QCD plasma. For the latter we consider the equation of state, kinetics, quasiparticles, flow properties and possible chaos and turbulence. The promise of phase space distribution functions for covariant transport and kinetic theory is stressed. The possibility and implications of a stochastic bag are spelled out. A simplified space-time model of hadronic collisions is pursued, with applications to A-A collisions and other matters. The domain wall between hadronic and plasma phase is of potential importance: its thickness and relation to surface tension are noticed. Finally we reviewed the recently developed stochastic cell model of multiparticle distributions and KNO scaling. This topic leads to the notion that fractal dimensions are involved in a rather general dynamical context. We speculate that various scaling phenomena are independent of the full dynamical structure, depending only on a general stochastic framework having to do with simple maps and strange attractors. 42 references.

  15. Collisional excitation of the highly excited hydrogen atoms in the dipole form of the semiclassical impact parameter and Born approximations

    NASA Technical Reports Server (NTRS)

    Omidvar, K.

    1971-01-01

    Expressions for the excitation cross section of the highly excited states of the hydrogenlike atoms by fast charged particles have been derived in the dipole approximation of the semiclassical impact parameter and the Born approximations, making use of a formula for the asymptotic expansion of the oscillator strength of the hydrogenlike atoms given by Menzel. When only the leading term in the asymptotic expansion is retained, the expression for the cross section becomes identical to the expression obtained by the method of the classical collision and correspondence principle given by Percival and Richards. Comparisons are made between the Bethe coefficients obtained here and the Bethe coefficients of the Born approximation for transitions where the Born calculation is available. Satisfactory agreement is obtained only for n yields n + 1 transitions, with n the principal quantum number of the excited state.

  16. Versatile high rate plasma deposition and processing with very high frequency excitation

    SciTech Connect

    Heintze, M.

    1997-07-01

    The interest in plasma deposition using very high frequency (VHF) excitation arose after the preparation of a-Si:H at high growth rates was demonstrated. Subsequently the improved process flexibility and the control of material properties offered by the variation of the plasma excitation frequency was recognized. The preparation of amorphous and microcrystalline thin films in a VHF-plasma is described. The increased growth rates have been attributed to an enhancement of film precursor formation at VHF, to the decreased sheath thickness as well as to an enhancement of the surface reactivity by positive ions. Plasma diagnostic investigations show that the parameters mainly affected by the excitation frequency are the ion flux to the electrodes as well as the sheaths potentials and widths, rather than the plasma density. 55 refs., 13 figs.

  17. Electron impact excitation of highly charged sodium-like ions

    NASA Technical Reports Server (NTRS)

    Blaha, M.; Davis, J.

    1978-01-01

    Optical transition probabilities and electron collision strengths for Ca X, Fe XVI, Zn XX, Kr XXVI and Mo XXXII are calculated for transitions between n equal to 3 and n equal to 4 levels. The calculations neglect relativistic effects on the radial functions. A semi-empirical approach provides wave functions of the excited states; a distorted wave function without exchange is employed to obtain the excitation cross sections. The density dependence of the relative intensities of certain emission lines in the sodium isoelectronic sequence is also discussed.

  18. Observation of low- and high-energy Gamow-Teller phonon excitations in nuclei.

    PubMed

    Fujita, Y; Fujita, H; Adachi, T; Bai, C L; Algora, A; Berg, G P A; von Brentano, P; Colò, G; Csatlós, M; Deaven, J M; Estevez-Aguado, E; Fransen, C; De Frenne, D; Fujita, K; Ganioğlu, E; Guess, C J; Gulyás, J; Hatanaka, K; Hirota, K; Honma, M; Ishikawa, D; Jacobs, E; Krasznahorkay, A; Matsubara, H; Matsuyanagi, K; Meharchand, R; Molina, F; Muto, K; Nakanishi, K; Negret, A; Okamura, H; Ong, H J; Otsuka, T; Pietralla, N; Perdikakis, G; Popescu, L; Rubio, B; Sagawa, H; Sarriguren, P; Scholl, C; Shimbara, Y; Shimizu, Y; Susoy, G; Suzuki, T; Tameshige, Y; Tamii, A; Thies, J H; Uchida, M; Wakasa, T; Yosoi, M; Zegers, R G T; Zell, K O; Zenihiro, J

    2014-03-21

    Gamow-Teller (GT) transitions in atomic nuclei are sensitive to both nuclear shell structure and effective residual interactions. The nuclear GT excitations were studied for the mass number A = 42, 46, 50, and 54 "f-shell" nuclei in ((3)He, t) charge-exchange reactions. In the (42)Ca → (42)Sc reaction, most of the GT strength is concentrated in the lowest excited state at 0.6 MeV, suggesting the existence of a low-energy GT phonon excitation. As A increases, a high-energy GT phonon excitation develops in the 6-11 MeV region. In the (54)Fe → (54)Co reaction, the high-energy GT phonon excitation mainly carries the GT strength. The existence of these two GT phonon excitations are attributed to the 2 fermionic degrees of freedom in nuclei. PMID:24702355

  19. Designing and modeling doubly porous polymeric materials

    NASA Astrophysics Data System (ADS)

    Ly, H.-B.; Le Droumaguet, B.; Monchiet, V.; Grande, D.

    2015-07-01

    Doubly porous organic materials based on poly(2-hydroxyethyl methacrylate) are synthetized through the use of two distinct types of porogen templates, namely a macroporogen and a nanoporogen. Two complementary strategies are implemented by using either sodium chloride particles or fused poly(methyl methacrylate) beads as macroporogens, in conjunction with ethanol as a porogenic solvent. The porogen removal respectively allows for the generation of either non-interconnected or interconnected macropores with an average diameter of about 100-200 μm and nanopores with sizes lying within the 100 nm order of magnitude, as evidenced by mercury intrusion porosimetry and scanning electron microscopy. Nitrogen sorption measurements evidence the formation of materials with rather high specific surface areas, i.e. higher than 140 m2.g-1. This paper also addresses the development of numerical tools for computing the permeability of such doubly porous materials. Due to the coexistence of well separated scales between nanopores and macropores, a consecutive double homogenization approach is proposed. A nanoscopic scale and a mesoscopic scale are introduced, and the flow is evaluated by means of the Finite Element Method to determine the macroscopic permeability. At the nanoscopic scale, the flow is described by the Stokes equations with an adherence condition at the solid surface. At the mesoscopic scale, the flow obeys the Stokes equations in the macropores and the Darcy equation in the permeable polymer in order to account for the presence of the nanopores.

  20. The Effects of Various Design Parameters on the Free Vibration of Doubly Curved Composite Sandwich Panels

    NASA Astrophysics Data System (ADS)

    CUNNINGHAM, P. R.; WHITE, R. G.; AGLIETTI, G. S.

    2000-02-01

    Sandwich panels have a very high stiffness to weight ratio, which makes them particularly useful in the aerospace industry where carbon fibre reinforced plastics and lightweight honeycomb cores are being used in the construction of floor panels, fairings and intake barrel panels. In the latter case, the geometry of the panels can be considered doubly curved. This paper presents an introduction to an ongoing study investigating the dynamic response prediction of acoustically excited composite sandwich panels which have double curvature. The final objective is to assess and hopefully produce an up to date set of acoustic fatigue design guidelines for this type of structure. The free vibration of doubly curved composite honeycomb sandwich panels is investigated here, both experimentally and theoretically, the latter using a commerically available finite element package. The design and manufacture of three test panels is covered before presenting experimental results for the natural frequencies of vibration with freely supported boundary conditions. Once validated against the experimental results, the theoretical investigation is extended to study the effects of changing radii of curvature, orthotropic properties of the core, and ply orientation on the natural frequencies of vibration of rectangular panels with various boundary conditions. The results from the parameter studies show curve veering, particularly when studying the effect of changing radii and ply orientation, however, it is not clear whether this phenomenon is due to the approximation method used or occurs in the physical system.

  1. Hidden Fermionic Excitation Boosting High-Temperature Superconductivity in Cuprates

    NASA Astrophysics Data System (ADS)

    Sakai, Shiro; Civelli, Marcello; Imada, Masatoshi

    2016-02-01

    The dynamics of a microscopic cuprate model, namely, the two-dimensional Hubbard model, is studied with a cluster extension of the dynamical mean-field theory. We find a nontrivial structure of the frequency-dependent self-energies, which describes an unprecedented interplay between the pseudogap and superconductivity. We show that these properties are well described by quasiparticles hybridizing with (hidden) fermionic excitations, emergent from the strong electronic correlations. The hidden fermion enhances superconductivity via a mechanism distinct from a conventional boson-mediated pairing, and originates the normal-state pseudogap. Though the hidden fermion is elusive in experiments, it can solve many experimental puzzles.

  2. Hidden Fermionic Excitation Boosting High-Temperature Superconductivity in Cuprates.

    PubMed

    Sakai, Shiro; Civelli, Marcello; Imada, Masatoshi

    2016-02-01

    The dynamics of a microscopic cuprate model, namely, the two-dimensional Hubbard model, is studied with a cluster extension of the dynamical mean-field theory. We find a nontrivial structure of the frequency-dependent self-energies, which describes an unprecedented interplay between the pseudogap and superconductivity. We show that these properties are well described by quasiparticles hybridizing with (hidden) fermionic excitations, emergent from the strong electronic correlations. The hidden fermion enhances superconductivity via a mechanism distinct from a conventional boson-mediated pairing, and originates the normal-state pseudogap. Though the hidden fermion is elusive in experiments, it can solve many experimental puzzles. PMID:26894730

  3. Activators of photoluminescence in calcite: evidence from high-resolution, laser-excited luminescence spectroscopy

    USGS Publications Warehouse

    Pedone, V.A.; Cercone, K.R.; Burruss, R.C.

    1990-01-01

    Laser-excited luminescence spectroscopy of a red-algal, biogenic calcite and a synthetic Mn-calcite can make the distinction between organic and trace-element activators of photoluminescence. Organic-activated photoluminescence in biogenic calcite is characterized by significant peak shifts and increasing intensity with shorter-wavelength excitation and by significant decreases in intensity after heating to ??? 400??C. In contrast, Mn-activated photoluminescence shows no peak shift, greatest intensity under green excitation and limited changes after heating. Examination of samples with a high-sensitivity spectrometer using several wavelengths of exciting light is necessary for identification of photoluminescence activators. ?? 1990.

  4. Nonlinear excitations in the honeycomb lattice: Beyond the high-symmetry points of the band structure

    NASA Astrophysics Data System (ADS)

    Arévalo, Edward; Morales-Molina, Luis

    2016-05-01

    The interplay between nonlinearity and the band structure of pristine honeycomb lattices is systematically explored. For that purpose, a theory of collective excitations valid for the first Brillouin zone of the lattice is developed. Closed-form expressions of two-dimensional excitations are derived for Bloch wave numbers beyond the high-symmetry points of the band structure. A description of the regions of validity of different nonlinear excitations in the first-Brillouin zone is given. We find that the unbounded nature of these excitations in nonlinear honeycomb latices is a signature of the strong influence of the Dirac cones in other parts of the band structure.

  5. Suppression of higher mode excitation in a high gain relativistic klystron amplifier

    NASA Astrophysics Data System (ADS)

    Wu, Y.; Xu, Z.; Jin, X.; Li, Z. H.; Tang, C. X.

    2012-02-01

    Suppressing higher mode excitation is very important in the high gain relativistic klystron amplifier because higher mode can seriously degrade klystron performance and cause pulse shortening. The mechanism of higher mode self-excitation is explored in the PIC simulation, and it is shown the coupling between cavities is the main cause of higher mode self-excitation. The coupling forms the positive feedback loop for higher mode to be excited just like that in the oscillator circuit. The formula for startup current of higher mode self-excitation is developed based on the coupling between cavities. And the corresponding methods are taken to avoid higher mode self-excitation. Finally, mode control is realized in the RKA with output power up to 1.02 GW when driven power is only few kilowatts.

  6. The doubly compactified Schwinger model

    SciTech Connect

    Linares, R.; Urrutia, L. F.; Vergara, J. D.

    1999-10-25

    In this note we summarize the exact solution of the doubly compactified Schwinger model (CSM), defined by the condition that the domain of the electromagnetic degree of freedom c=1/L{integral}{sub 0}{sup L}dxA{sub 1} is -c-bar

  7. Quenching of highly rotationally excited HCl in collisions with He

    SciTech Connect

    Yang, Benhui; Stancil, P. C. E-mail: stancil@physast.uga.edu

    2014-03-10

    We report rotational quenching cross sections and rate coefficients of HCl due to collisions with He. The close-coupling method and the coupled-states approximation are applied in quantum-mechanical scattering calculations of state-to-state cross sections for HCl with initial rotational levels up to j = 20 for kinetic energies from 10{sup –5} to 15,000 cm{sup –1}. State-to-state rate coefficients for temperatures between 0.1 and 3000 K are also presented. Comparison of the present rate coefficients with previous results reported in the literature for lowly excited rotational levels shows reasonable agreement. Small differences are attributed to the differences in the interaction potential energy surfaces. The uncertainty in the computed cross sections and rate coefficients is estimated by varying the potential well depth. Applications of current results to astrophysical systems are also briefly discussed.

  8. Intersystem crossing from highly excited states. rhodamine 6G

    SciTech Connect

    Ryl'kov, V.V.; Cheshev, E.A.

    1985-09-01

    The authors carried out an investigation of ethanolic solutions of Rhodamine 6G (R6G) at 20 C by laser flash photolysis. The excitation of dilute (3 /SUP ./ 10/sup -5/ M) solutions of R6G with an initial optical density of 1.5 up to an intensity of 100 MW/cm/sup 2/ resulted in only weak triplet-triplet absorption. The introduction of additions of lithium chloride or lithium bromide in 0.1 M concentrations into a solution of R6G (3.10/sup -5/ M) resulted in the appearance of induced absorption and the introduction of an addition of lithium nitrate in the same concentration into the solution did not result in enhancement of triplet-triplet absorption.

  9. Revised and extended level scheme of the doubly-odd nucleus {sup 188}Ir

    SciTech Connect

    Jungclaus, A.; Modamio, V.; Egido, J. L.; Fernandez, M. A.; Schwengner, R.; Algora, A.; Bazzacco, D.; Lenzi, S.; Marginean, N.; Ur, C. A.; Escrig, D.; Fraile, L. M.; Martinez, T.; Napoli, D. R.

    2008-02-15

    High-spin states in the doubly odd Z=77 nucleus {sup 188}Ir were studied using the reaction {sup 186}W({sup 7}Li, 5n) at 59 MeV and the GASP spectrometer for {gamma}-ray detection. The level structures recently suggested to be built on the known 4.1(3) ms isomeric state of this nucleus have been considerably revised and extended and an isomer with a lifetime of 17.7(2) ns has been identified within the main decay sequence. In addition two rotational bands built on low spin states below the ms isomer have been observed for the first time. The basic features of the excitation scheme of {sup 188}Ir are discussed within the Hartree-Fock-Bogoliubov theory within the Lipkin-Nogami approach with the finite-range density-dependent Gogny force.

  10. Note: Excited State Studies of Ozone using State-Specific Multireference Coupled Cluster Methods

    SciTech Connect

    Bhaskaran-Nair, Kiran; Kowalski, Karol

    2012-12-07

    Vertical excitation energies obtained with state-specific multi-reference coupled cluster (MRCC) methods are reported for the ozone molecule. Using state-specific MRCC non-iterative methods with singles, doubles, and non-iterative triples (MRCCSD(T)) we obtain 4.40 eV for the challenging doubly excited 21A1 state when using a reliable model space. This estimate is in good agreement with experiment (4.5 eV). We also compare our MRCC results with the excitation energies obtained with high-order equation-of-motion coupled cluster methods

  11. The Doubly Exceptional Child: A Principal's Dilemma.

    ERIC Educational Resources Information Center

    Kesner, Rebecca J., Ed.

    2002-01-01

    This document contains two articles concerned with doubly exceptional children and gifted education. In "The Doubly Exceptional Child: A Principal's Dilemma," (Carol J. Mills and Linda E. Brody), such children do not fit into the usual categories for sorting children because their gifts and disabilities often mask each other. Suggestions are…

  12. Non-iridescent Transmissive Structural Color Filter Featuring Highly Efficient Transmission and High Excitation Purity

    PubMed Central

    Shrestha, Vivek Raj; Lee, Sang-Shin; Kim, Eun-Soo; Choi, Duk-Yong

    2014-01-01

    Nanostructure based color filtering has been considered an attractive replacement for current colorant pigmentation in the display technologies, in view of its increased efficiencies, ease of fabrication and eco-friendliness. For such structural filtering, iridescence relevant to its angular dependency, which poses a detrimental barrier to the practical development of high performance display and sensing devices, should be mitigated. We report on a non-iridescent transmissive structural color filter, fabricated in a large area of 76.2 × 25.4 mm2, taking advantage of a stack of three etalon resonators in dielectric films based on a high-index cavity in amorphous silicon. The proposed filter features a high transmission above 80%, a high excitation purity of 0.93 and non-iridescence over a range of 160°, exhibiting no significant change in the center wavelength, dominant wavelength and excitation purity, which implies no change in hue and saturation of the output color. The proposed structure may find its potential applications to large-scale display and imaging sensor systems. PMID:24815530

  13. Proceedings of the 1984 workshop on high-energy excitations in condensed matter. Volume II

    SciTech Connect

    Silver, R.N.

    1984-12-01

    This volume covers electronic excitations, momentum distributions, high energy photons, and a wrap-up session. Abstracts of individual items from the conference were prepared separately for the data base. (GHT)

  14. Millimeter- and submillimeter-wave spectrum of highly excited states of water

    NASA Astrophysics Data System (ADS)

    Pearson, J. C.; De Lucia, Frank C.; Anderson, Todd; Herbst, Eric; Helminger, Paul

    1991-09-01

    To facilitate studies of water in the interstellar medium and late-type stars, the frequencies of 30 new millimeter- and submillimeter-wave transitions of H2O-16 have been measured, which lie between 100 GHz and 600 GHz. This represents almost a doubling of the number of water lines that have been observed in the laboratory in this spectral region at high resolution. All of the newly observed lines are highly excited, lying between 2400 and 4200/cm above the ground level. Some of these have large excitation energies because of their high rotational states and others because they lie in excited vibrational states. These lines are potentially of substantial astrophysical significance because they are related to the study of interstellar masers and because their high excitation eliminates the atmospheric self-absorption associated with the more well-known water lines.

  15. Ag-SiO₂-Er₂O₃ nanocomposites: highly effective upconversion luminescence at high power excitation and high temperature.

    PubMed

    Xu, Wen; Min, Xiaolei; Chen, Xu; Zhu, Yongsheng; Zhou, Pingwei; Cui, Shaobo; Xu, Sai; Tao, Li; Song, Hongwei

    2014-01-01

    Rare Earth (RE) activated upconversion phosphors (UCPs), have demonstrated significant application potentials in some front fields, including solar energy conversion and bio-application. However, some bottleneck problems should be overcame, such as the lower upconversion efficiency, narrower excitation band, concentration-quenching and temperature-quenching. To solve these problems, the Ag-SiO2-Er2O3 nanocomposites were fabricated, in which the upconversion luminescence (UCL) of Er2O3 was white broadband. Through the interaction of Er2O3 with surface plasmon (SP) of silver nanoparticles (SNPs), the threshold power for generating broadbands was suppressed largely in contrast to the Er2O3 nanoparticles (NPs), while the UCL brightness was enhanced remarkably, ranging from several to 10(4) times, which strongly depended on the power density of excitation light. At excitation power density of 1.50 W/mm(2) of 980 nm light, the UCL intensity of Ag-SiO2-Er2O3 is 40-folds than the well-known NaYF4:Yb(3+),Er(3+) commercial powders. And more, it is also interesting to observe that the composites demonstrate two excitation bands extending of 780-980 nm, highly improved UCL with elevated temperature and excitation power density. The UCL mechanism related to UCL enhancement was carefully studied. PMID:24867159

  16. Recent results on giant dipole resonance decays in highly excited nuclei

    SciTech Connect

    Snover, K.A.

    1991-12-31

    Some recent results on Giant Dipole Resonance (GDR) decays in highly excited, equilibrated nuclei, are discussed based primarily on work done at Seattle. Four sections address the following topics: oblate shapes of rotating, highly excited Zr--Mo nuclei; adiabatic versus `motionally narrowed` GDR decay; large spin-driven deformations observed in hot medium-mass nuclei; and search for entrance channel effects in GDR decay following {sup 58}Ni {plus} {sup 92}Zr fusion. 22 refs.

  17. Recent results on giant dipole resonance decays in highly excited nuclei

    SciTech Connect

    Snover, K.A.

    1991-01-01

    Some recent results on Giant Dipole Resonance (GDR) decays in highly excited, equilibrated nuclei, are discussed based primarily on work done at Seattle. Four sections address the following topics: oblate shapes of rotating, highly excited Zr--Mo nuclei; adiabatic versus motionally narrowed' GDR decay; large spin-driven deformations observed in hot medium-mass nuclei; and search for entrance channel effects in GDR decay following [sup 58]Ni [plus] [sup 92]Zr fusion. 22 refs.

  18. Doubly charged CO2 clusters formed by ionization of doped helium nanodroplets☆

    PubMed Central

    Daxner, Matthias; Denifl, Stephan; Scheier, Paul; Echt, Olof

    2014-01-01

    Helium nanodroplets are doped with carbon dioxide and ionized by electrons. Doubly charged cluster ions are, for the first time, identified based on their characteristic patterns of isotopologues. Thanks to the high mass resolution, large dynamic range, and a novel method to eliminate contributions from singly charged ions from the mass spectra, we are able to observe doubly charged cluster ions that are smaller than the ones reported in the past. The likely mechanism by which doubly charged ions are formed in doped helium droplets is discussed. PMID:25844051

  19. Doping dependence of spin excitations and its correlations with high-temperature superconductivity in iron pnictides

    PubMed Central

    Wang, Meng; Zhang, Chenglin; Lu, Xingye; Tan, Guotai; Luo, Huiqian; Song, Yu; Wang, Miaoyin; Zhang, Xiaotian; Goremychkin, E.A.; Perring, T.G.; Maier, T.A.; Yin, Zhiping; Haule, Kristjan; Kotliar, Gabriel; Dai, Pengcheng

    2013-01-01

    High-temperature superconductivity in iron pnictides occurs when electrons and holes are doped into their antiferromagnetic parent compounds. Since spin excitations may be responsible for electron pairing and superconductivity, it is important to determine their electron/hole-doping evolution and connection with superconductivity. Here we use inelastic neutron scattering to show that while electron doping to the antiferromagnetic BaFe2As2 parent compound modifies the low-energy spin excitations and their correlation with superconductivity (<50 meV) without affecting the high-energy spin excitations (>100 meV), hole-doping suppresses the high-energy spin excitations and shifts the magnetic spectral weight to low-energies. In addition, our absolute spin susceptibility measurements for the optimally hole-doped iron pnictide reveal that the change in magnetic exchange energy below and above Tc can account for the superconducting condensation energy. These results suggest that high-Tc superconductivity in iron pnictides is associated with both the presence of high-energy spin excitations and a coupling between low-energy spin excitations and itinerant electrons. PMID:24301219

  20. State-resolved collisional relaxation of highly vibrationally excited CsH by CO2

    NASA Astrophysics Data System (ADS)

    Mu, Baoxia; Cui, Xiuhua; Shen, Yifan; Dai, Kang

    2015-09-01

    Quenching of highly vibrationally excited CsH(X1Σ+, v = 15-23) by collisions with CO2 was investigated. A significant fraction of the initial population of highly vibrationally excited CsH(v = 22) was relaxed to a low vibrational level (Δv = -5). The near-resonant 5-1 vibration-to-vibration (V-V) energy was efficiently exchanged. The rate constants for the rotational levels of CO2(0000) [J = 36-60] and CO2(0001) [J = 5-31] from the collisions with excited CsH were determined. The experiments revealed that the collisions resulting in CO2(0000) were accompanied by substantial excitation in rotation and translation. The vibrationally excited CO2(0001) state exhibited rotational and translational energy distributions near those of the initial state. The total quenching rates relative to the probed state of excited CsH were determined for both CO2 states. The corresponding data indicated that the gains in the rotational and translational energies in CO2 were sensitive to the collisional depletion of excited CsH.

  1. Effects of Hemodiafiltration and High Flux Hemodialysis on Nerve Excitability in End-Stage Kidney Disease

    PubMed Central

    Arnold, Ria; Pussell, Bruce A.; Pianta, Timothy J.; Grinius, Virginija; Lin, Cindy S-Y.; Kiernan, Matthew C.; Howells, James; Jardine, Meg J.; Krishnan, Arun V.

    2013-01-01

    Objectives Peripheral neuropathy is the most common neurological complication in end-stage kidney disease. While high flux hemodialysis (HFHD) and hemodiafiltration (HDF) have become the preferred options for extracorporeal dialysis therapy, the effects of these treatments on nerve excitability have not yet been examined. Methods An observational proof-of-concept study of nerve excitability and neuropathy was undertaken in an incident dialysis population (n = 17) receiving either HFHD or HDF. Nerve excitability techniques were utilised to assess nerve ion channel function and membrane potential, in conjunction with clinical assessment and standard nerve conduction studies. A mathematical model of axonal excitability was used to investigate the underlying basis of the observed changes. Nerve excitability was recorded from the median nerve, before, during and after a single dialysis session and correlated with corresponding biochemical markers. Differences in nerve excitability were compared to normal controls with longitudinal follow-up over an 18 month period. Results Nerve excitability was performed in patient cohorts treated with either HFHD (n = 9) or online HDF (n = 8), with similar neuropathy status. Nerve excitability measures in HDF-treated patients were significantly closer to normal values compared to HFHD patients obtained over the course of a dialysis session (p<0.05). Longitudinal studies revealed stability of nerve excitability findings, and thus maintenance of improved nerve function in the HDF group. Conclusions This study has provided evidence that nerve excitability in HDF-treated patients is significantly closer to normal values prior to dialysis, across a single dialysis session and at longitudinal follow-up. These findings offer promise for the management of neuropathy in ESKD and should be confirmed in randomised trials. PMID:23536855

  2. Doubly rotated contoured quartz resonators.

    PubMed

    Sinha, B K

    2001-09-01

    Doubly rotated contoured quartz resonators are used in the design of temperature-compensated stable clocks and dual-mode sensors for simultaneous measurements of pressure and temperature. The design of these devices is facilitated by models that can predict frequency spectra associated with the three thickness modes and temperature and stress-induced frequency changes as a function of crystalline orientation. The Stevens-Tiersten technique for the analysis of the C-mode of a doubly rotated contoured quartz resonator is extended to include the other two thickness modes. Computational results for harmonic and anharmonic overtones of all three thickness modes of such resonators help in optimizing the radius of curvature of the contour and electrode shape for suppression of unwanted modes and prevention of activity dips. The temperature and stress-induced changes in thickness-mode resonator frequencies are calculated from a perturbation technique for small dynamic fields superposed on a static bias. The static bias refers to either a temperature or stress-induced static deformation of the resonator plate. Phenomenological models are also used for calculating the temperature and stress-induced changes in resonant frequencies as a function of crystalline orientation. Results for the SBTC-cut quartz plate with a spherical convex contour of 260 mm indicate that normal trapping occurs for the third (n = 3) and fifth (n = 5) harmonic of the A-mode, the fundamental (n = 1) and third (n = 3) harmonic of the B-mode, and the fundamental (n = 1) and fifth (n = 5) harmonic of the C-mode. PMID:11570746

  3. A highly optimized code for calculating atomic data at neutron star magnetic field strengths using a doubly self-consistent Hartree-Fock-Roothaan method

    NASA Astrophysics Data System (ADS)

    Schimeczek, C.; Engel, D.; Wunner, G.

    2012-07-01

    Our previously published code for calculating energies and bound-bound transitions of medium-Z elements at neutron star magnetic field strengths [D. Engel, M. Klews, G. Wunner, Comput. Phys. Comm. 180 (2009) 302-311] was based on the adiabatic approximation. It assumes a complete decoupling of the (fast) gyration of the electrons under the action of the magnetic field and the (slow) bound motion along the field under the action of the Coulomb forces. For the single-particle orbitals this implied that each is a product of a Landau state and an (unknown) longitudinal wave function whose B-spline coefficients were determined self-consistently by solving the Hartree-Fock equations for the many-electron problem on a finite-element grid. In the present code we go beyond the adiabatic approximation, by allowing the transverse part of each orbital to be a superposition of Landau states, while assuming that the longitudinal part can be approximated by the same wave function in each Landau level. Inserting this ansatz into the energy variational principle leads to a system of coupled equations in which the B-spline coefficients depend on the weights of the individual Landau states, and vice versa, and which therefore has to be solved in a doubly self-consistent manner. The extended ansatz takes into account the back-reaction of the Coulomb motion of the electrons along the field direction on their motion in the plane perpendicular to the field, an effect which cannot be captured by the adiabatic approximation. The new code allows for the inclusion of up to 8 Landau levels. This reduces the relative error of energy values as compared to the adiabatic approximation results by typically a factor of three (1/3 of the original error), and yields accurate results also in regions of lower neutron star magnetic field strengths where the adiabatic approximation fails. Further improvements in the code are a more sophisticated choice of the initial wave functions, which takes into

  4. Properties of high-energy isoscalar monopole excitations in medium-heavy mass spherical nuclei

    SciTech Connect

    Gorelik, M. L. Shlomo, Sh. Tulupov, B. A. Urin, M. H.

    2015-07-15

    The recently developed particle-hole dispersive optical model is applied to describe properties of high-energy isoscalar monopole excitations in medium-heavy mass spherical nuclei. In particular, the double transition density averaged over the energy of the isoscalar monopole excitations is considered for {sup 208}Pb in a wide energy interval, which includes the isoscalar giant monopole resonance and its overtone. The energy-averaged strength functions of these resonances are also analyzed.

  5. Spectroscopy of doubly charmed baryons from lattice QCD

    SciTech Connect

    Padmanath, M.; Edwards, Robert G.; Mathur, Nilmani; Peardon, Michael

    2015-05-06

    This study presents the ground and excited state spectra of doubly charmed baryons from lattice QCD with dynamical quark fields. Calculations are performed on anisotropic lattices of size 16³ × 128, with inverse spacing in temporal direction at⁻¹=5.67(4) GeV and with a pion mass of about 390 MeV. A large set of baryonic operators that respect the symmetries of the lattice yet which retain a memory of their continuum analogues are used. These operators transform as irreducible representations of SU(3)F symmetry for flavor, SU(4) symmetry for Dirac spins of quarks and O(3) for spatial symmetry. The distillation method is utilized to generate baryon correlation functions which are analyzed using the variational fitting method to extract excited states. The lattice spectra obtained have baryonic states with well-defined total spins up to 7/2 and the pattern of low-lying states does not support the diquark picture for doubly charmed baryons. On the contrary the calculated spectra are remarkably similar to the expectations from models with an SU(6)×O(3) symmetry. Various spin-dependent energy splittings between the extracted states are also evaluated.

  6. Spectroscopy of doubly charmed baryons from lattice QCD

    NASA Astrophysics Data System (ADS)

    Padmanath, M.; Edwards, Robert G.; Mathur, Nilmani; Peardon, Michael; Hadron Spectrum Collaboration

    2015-05-01

    We present the ground and excited state spectra of doubly charmed baryons from lattice QCD with dynamical quark fields. Calculations are performed on anisotropic lattices of size 1 63×128 , with inverse spacing in temporal direction at-1=5.67 (4 ) GeV and with a pion mass of about 390 MeV. A large set of baryonic operators that respect the symmetries of the lattice yet which retain a memory of their continuum analogues are used. These operators transform as irreducible representations of SU(3 ) F symmetry for flavor, SU(4) symmetry for Dirac spins of quarks and O(3) for spatial symmetry. The distillation method is utilized to generate baryon correlation functions which are analyzed using the variational fitting method to extract excited states. The lattice spectra obtained have baryonic states with well-defined total spins up to 7 /2 and the pattern of low-lying states does not support the diquark picture for doubly charmed baryons. On the contrary the calculated spectra are remarkably similar to the expectations from models with an SU (6 )×O (3 ) symmetry. Various spin-dependent energy splittings between the extracted states are also evaluated.

  7. High-velocity, high-excitation neutral carbon in a cloud in the Vela supernova remnant

    NASA Technical Reports Server (NTRS)

    Jenkins, Edward B.; Wallerstein, George

    1995-01-01

    HD 72089 is situated behind the Vela supernova remnant, and the interstellar absorption lines in the spectrum of this star are remarkable for two reasons. First, there are six distinct velocity components that span the (heliocentric) velocity range -60 to +121 km/s in the lines of Na I and Ca II. Second, two of the components at high velocity, one at +85 km/s and another at +121.5 km/s, have densities that are large enough to produce observable lines from neutral carbon. The gas moving at +121.5 km/s has such a large pressure that the excited fine-structure levels of the ground electronic state of C I are collisionally populated nearly in proportion to their level degeneracies. This high-velocity gas exhibits unusually low column densities of Mg I and Na I, compared to that of C I. We propose that the +121.5 km/s component represents gas that has cooled and recombined in a zone that follows a shock driven into a cloud by the very recent passage of a supernova blast wave. A representative preshock density of n(sub H) approximately = 13/cc and velocity v(sub s) = 100 km/s is indicated by the strength of diffuse (O III) emission lines seen in directions very near HD 72089. The strong collisional population of excited C I and apparent absence of excited levels of O I give a most favorable fit to the conditions 1000 less than n(sub H) less than 2900/cc over a temperature range 300 less than T less than 1000 K. The fact that the compression is not substantially more than this indicates that the preshock gas may have had an embedded, transverse magnetic field with a strength B greater than or approximately = 1 micro-G. The large dynamical pressure of the supernova blast wave that would be needed to create the cloud shock that we describe implies that the energy of the supernova was 8 x 10(exp 51) ergs, if the Vela remnant is 500 pc away. We can bring this value much closer to typical supernova energies E less than or approximately = 10(exp 51) ergs if the distance to the

  8. Some General Effects of Strong High-Frequency Excitation: Stiffening, Biasing and Smoothening

    NASA Astrophysics Data System (ADS)

    THOMSEN, J. J.

    2002-06-01

    Mechanical high-frequency (HF) excitation provides a working principle behind many industrial and natural applications and phenomena. This paper concerns three particular effects of HF excitation, that may change the apparent characteristics of mechanical systems: (1) stiffening, by which the apparent linear stiffness associated with an equilibrium is changed, along with derived quantities such as stability and natural frequencies; (2) biasing by which the system is biased towards a particular state, static or dynamic, which does not exist or is unstable in the absence of the HF excitation; and (3) smoothening, referring to a tendency for discontinuities to be effectively “smeared out” by HF excitation. Illustrating first these effects for a few specific systems, analytical results are provided that quantify them for a quite general class of mechanical systems. This class covers systems that can be modelled by a finite number of second order ordinary differential equations, generally non-linear, with periodically oscillating excitation terms of high frequency and small amplitude. The results should be useful for understanding the effects in question in a broader perspective than is possible with specific systems, for calculating effects for specific systems using well-defined formulas, and for possibly designing systems that display prescribed characteristics in the presence of HF excitation.

  9. Observation of two-α emission from high-lying excited states of Ne18 by complete-kinematics measurements

    NASA Astrophysics Data System (ADS)

    Xu, X. X.; Lin, C. J.; Jia, H. M.; Yang, F.; Jia, F.; Wu, Z. D.; Zhang, S. T.; Liu, Z. H.; Zhang, H. Q.; Xu, H. S.; Sun, Z. Y.; Wang, J. S.; Hu, Z. G.; Wang, M.; Chen, R. F.; Zhang, X. Y.; Li, C.; Lei, X. G.; Xu, Z. G.; Xiao, G. Q.; Zhan, W. L.

    2010-12-01

    Two-α emission from high-lying excited states of Ne18 was studied by complete-kinematics measurements. The Ne18 beam at the energy of 51.8 MeV/u was bombarding a Au197 target to populate the excited states via Coulomb excitation. Products of two-α emission, C10-α-α, were measured by an array of silicon strip detectors and a CsI + PIN telescope. With the help of Monte Carlo simulations, the experimental results show the characteristics of sequential two-α emission via O14 excited states. Sequential two-α and two-proton emissions from Ne18 via one-particle daughter states are compared and the distinction of the opening angles of these two modes originates from the difference of the mass ratio of emitted particles to daughter nuclei.

  10. High-lying excited states in Gamow Teller strength and their roles in neutrino reactions

    NASA Astrophysics Data System (ADS)

    Cheoun, Myung-Ki; Ha, Eunja; Kajino, Toshitaka

    2012-10-01

    The Gamow Teller (GT) transition strengths deduced from charge exchange reactions (CEXRs) are very helpful for understanding the nuclear reaction induced by neutrinos, in particular, by the solar neutrino. For further study of supernovae (SNe) neutrinos in the cosmos, one needs to study high-lying GT states around a few tens of MeV region as well as other multipole transitions because of the high energy tail in the neutrino spectra emitted from the neutrino sphere. In this report, we address the importance of the high-lying GT excited states, whose data now become available from various CEXR experiments. For example, GT(± strengths up to 70MeV are successfully extracted by 90Zr( n, p) and 90Zr( p, n) reactions. Our discussions are extended to investigate roles of the high-lying states beyond a few low-lying states known in the old experiment on the reaction induced by SNe neutrinos particularly on 40Ar target. The nucleus was originally exploited to identify the solar neutrino emitted from 8B produced in the pp-chains on the Sun, and now lots of applications for more energetic neutrino detection are under progress. The expected large difference between the cross-sections of νe^{} and bar{{ν}}e^{} reactions on 40Ar , whose differences were anticipated because of the large Q-value in the bar{{ν}}e^{} reaction, is significantly diminished compared to previous results. Our calculations are carried out by the Quasi-particle Random Phase Approximation (QRPA), which takes the neutron-proton pairing into account to the standard proton-neutron QRPA (pnQRPA) where only proton-proton and neutron-neutron pairing correlations are considered.

  11. High frequency excitation waveform for efficient operation of a xenon excimer dielectric barrier discharge lamp

    NASA Astrophysics Data System (ADS)

    Beleznai, Sz; Mihajlik, G.; Maros, I.; Balázs, L.; Richter, P.

    2010-01-01

    The application of a high frequency (~2.5 MHz) burst (amplitude-modulated sinusoidal) excitation voltage waveform is investigated for driving a fluorescent dielectric barrier discharge (DBD) light source. The excitation waveform presents a novel method for generating spatially stable homogeneous Xe DBD possessing a high conversion efficiency from electrical energy to VUV Xe_{2}^{\\ast} excimer radiation (~172 nm), even at a significantly higher electrical energy deposition than realized by pulsed excitation. Simulation and experimental results predict discharge efficiencies around 60%. Lamp efficacy above 74 lm W-1 has been achieved. VUV emission and loss mechanisms are investigated extensively and the performance of burst and pulsed waveforms is compared both theoretically and experimentally.

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

    PubMed

    Aller, L H; Keyes, C D

    1980-03-01

    Observations of seven high-excitation planetary nebulae secured with the International Ultraviolet Explorer (IUE) satellite were combined with extensive ground-based data to obtain electron densities, gas kinetic temperatures, and ionic concentrations. We then employed a network of theoretical model nebulae to estimate the factors by which observed ionic concentrations must be multiplied to obtain elemental abundances. Comparison with a large sample of nebulae for which extensive ground-based observations have been obtained shows nitrogen to be markedly enhanced in some of these objects. Possibly most, if not all, high-excitation nebulae evolve from stars that have higher masses than progenitors of nebulae of low-to-moderate excitation. PMID:16592781

  13. Existence of an exotic torus configuration in high-spin excited states of 40Ca.

    PubMed

    Ichikawa, T; Maruhn, J A; Itagaki, N; Matsuyanagi, K; Reinhard, P-G; Ohkubo, S

    2012-12-01

    We investigate the possibility of the existence of the exotic torus configuration in the high-spin excited states of (40)Ca. We here consider the spin alignments about the symmetry axis. To this end, we use a three-dimensional cranked Skyrme Hartree-Fock method and search for stable single-particle configurations. We find one stable state with the torus configuration at the total angular momentum J=60 ħ and an excitation energy of about 170 MeV in all calculations using various Skyrme interactions. The total angular momentum J=60 ħ consists of aligned 12 nucleons with the orbital angular momenta Λ=+4, +5, and +6 for spin-up or -down neutrons and protons. The obtained results strongly suggest that a macroscopic amount of circulating current breaking the time-reversal symmetry emerges in the high-spin excited state of (40)Ca. PMID:23368188

  14. Low excitatory innervation balances high intrinsic excitability of immature dentate neurons

    PubMed Central

    Dieni, Cristina V.; Panichi, Roberto; Aimone, James B.; Kuo, Chay T.; Wadiche, Jacques I.; Overstreet-Wadiche, Linda

    2016-01-01

    Persistent neurogenesis in the dentate gyrus produces immature neurons with high intrinsic excitability and low levels of inhibition that are predicted to be more broadly responsive to afferent activity than mature neurons. Mounting evidence suggests that these immature neurons are necessary for generating distinct neural representations of similar contexts, but it is unclear how broadly responsive neurons help distinguish between similar patterns of afferent activity. Here we show that stimulation of the entorhinal cortex in mouse brain slices paradoxically generates spiking of mature neurons in the absence of immature neuron spiking. Immature neurons with high intrinsic excitability fail to spike due to insufficient excitatory drive that results from low innervation rather than silent synapses or low release probability. Our results suggest that low synaptic connectivity prevents immature neurons from responding broadly to cortical activity, potentially enabling excitable immature neurons to contribute to sparse and orthogonal dentate representations. PMID:27095423

  15. Collisional energy transfer in highly vibrationally excited molecules. Summary report, June 1980-May 1981

    SciTech Connect

    Crim, F.F.

    1981-03-01

    Combining the techniques of direct excitation of overtone vibrations and time resolved spectroscopic detection permits detailed measurements of the vibrational and rotational relaxation of highly vibrationally excited molecules. Using this technique, we have measured vibrational and rotational relaxation in HF(v = 3, 4, 5). By observing near-infrared fluorescence, we determine the self-relaxation probabilities for HF(v = 3, 4, 5) to be 0.19, 0.47, and 0.97, respectively, and find that the rates decrease more rapidly with temperature in these high levels than for v = 1. Using laser double resonance to probe individual rotational states, we find phenomenological rotational relaxation rate constants which decrease montonically with rotational energy change in the vibrationally excited molecule.

  16. Low excitatory innervation balances high intrinsic excitability of immature dentate neurons.

    PubMed

    Dieni, Cristina V; Panichi, Roberto; Aimone, James B; Kuo, Chay T; Wadiche, Jacques I; Overstreet-Wadiche, Linda

    2016-01-01

    Persistent neurogenesis in the dentate gyrus produces immature neurons with high intrinsic excitability and low levels of inhibition that are predicted to be more broadly responsive to afferent activity than mature neurons. Mounting evidence suggests that these immature neurons are necessary for generating distinct neural representations of similar contexts, but it is unclear how broadly responsive neurons help distinguish between similar patterns of afferent activity. Here we show that stimulation of the entorhinal cortex in mouse brain slices paradoxically generates spiking of mature neurons in the absence of immature neuron spiking. Immature neurons with high intrinsic excitability fail to spike due to insufficient excitatory drive that results from low innervation rather than silent synapses or low release probability. Our results suggest that low synaptic connectivity prevents immature neurons from responding broadly to cortical activity, potentially enabling excitable immature neurons to contribute to sparse and orthogonal dentate representations. PMID:27095423

  17. Low excitatory innervation balances high intrinsic excitability of immature dentate neurons

    DOE PAGESBeta

    Dieni, Cristina V.; Panichi, Roberto; Aimone, James B.; Kuo, Chay T.; Wadiche, Jacques I.; Overstreet-Wadiche, Linda

    2016-04-20

    Persistent neurogenesis in the dentate gyrus produces immature neurons with high intrinsic excitability and low levels of inhibition that are predicted to be more broadly responsive to afferent activity than mature neurons. Mounting evidence suggests that these immature neurons are necessary for generating distinct neural representations of similar contexts, but it is unclear how broadly responsive neurons help distinguish between similar patterns of afferent activity. Here we show that stimulation of the entorhinal cortex in mouse brain slices paradoxically generates spiking of mature neurons in the absence of immature neuron spiking. Immature neurons with high intrinsic excitability fail to spikemore » due to insufficient excitatory drive that results from low innervation rather than silent synapses or low release probability. Here, our results suggest that low synaptic connectivity prevents immature neurons from responding broadly to cortical activity, potentially enabling excitable immature neurons to contribute to sparse and orthogonal dentate representations.« less

  18. Mapping Ultrafast Dynamics of Highly Excited H2by Attosecond VUV-Radiation

    NASA Astrophysics Data System (ADS)

    Weber, Thorsten; Sturm, Felix; Wright, Travis; Ray, Dipanwita; Shivaram, Niranjan; Slaughter, Daniel; Bocharova, Irina; Ranitovic, Predrag; Belkacem, Ali

    2016-05-01

    We show how attosecond vacuum ultraviolet (VUV) and femtosecond infrared (IR) radiation can be used to excite and map dynamics of a highly excited neutral hydrogen molecule. By using time-delayed, strong laser pulses and ion imaging, we map the dynamics of highly-excited, bound states of hydrogen molecules. Due to the large stretching amplitude of the B electronic state, excited by the 9th harmonic of the fundamental laser frequency, the effective ionization potential of the hydrogen molecular ion changes substantially as the nuclear wave packet (NWP) vibrates in the bound, B potential energy curve. Therefore, the probability of ionizing the neutrally-excited hydrogen molecule by the IR probe pulse changes as the NWP evolves in the B potential. We probe this dynamics by ionizing the vibrating molecule by means of time-delayed IR radiation, and identify the dissociation channels with 3D-momentum ion imaging. Supported by DOE under Contract No. DE-AC02-05CH11231.

  19. Theoretical investigation of intramolecular vibrational energy redistribution in highly excited HFCO

    NASA Astrophysics Data System (ADS)

    Pasin, Gauthier; Gatti, Fabien; Iung, Christophe; Meyer, Hans-Dieter

    2006-05-01

    The present paper is devoted to the simulations of the intramolecular vibrational energy redistribution (IVR) in HFCO initiated by an excitation of the out-of-plane bending vibration [nν6=2,4,6,…,18,20]. Using a full six-dimensional ab initio potential energy, the multiconfiguration time-dependent Hartree (MCTDH) method was exploited to propagate the corresponding six-dimensional wave packets. This study emphasizes the stability of highly excited states of the out-of-plane bending mode which exist even above the dissociation threshold. More strikingly, the structure of the IVR during the first step of the dynamics is very stable for initial excitations ranging from 2ν6 to 20ν6. This latter result is consistent with the analysis of the eigenstates obtained, up to 10ν6, with the aid of the Davidson algorithm in a foregoing paper [Iung and Ribeiro, J. Chem. Phys. 121, 174105 (2005)]. The present study can be considered as complementary to this previous investigation. This paper also shows how MCTDH can be used to predict the dynamical behavior of a strongly excited system and to determine the energies of the corresponding highly excited states.

  20. Validity of Eucken formula and Stokes’ viscosity relation in high-temperature electronically excited gases

    SciTech Connect

    Istomin, V. A.; Kustova, E. V.; Mekhonoshina, M. A.

    2014-12-09

    In the present work we evaluate the accuracy of the Eucken formula and Stokes’ viscosity relation in high temperature non-equilibrium air species with electronic excitation. The thermal conductivity coefficient calculated using the exact kinetic theory methods is compared with that obtained applying approximate formulas in the temperature range 200–20000 K. A modification of the Eucken formula providing a good agreement with exact calculations is proposed. It is shown that the Stokes viscosity relation is not valid in electronically excited monoatomic gases at temperatures higher than 2000 K.

  1. High excitation power photoluminescence studies of ultra-low density GaAs quantum dots

    SciTech Connect

    Sonnenberg, D.; Graf, A.; Paulava, V.; Heyn, Ch.; Hansen, W.

    2013-12-04

    We fabricate GaAs epitaxial quantum dots (QDs) by filling of self-organized nanoholes in AlGaAs. The QDs are fabricated under optimized process conditions and have ultra-low density in the 10{sup 6} cm{sup −2} regime. At low excitation power the optical emission of single QDs exhibit sharp excitonic lines, which are attributed to the recombination of excitonic and biexcitonic states. High excitation power measurements reveal surprisingly broad emission lines from at least six QD shell states.

  2. Collision dynamics of methyl radicals and highly vibrationally excited molecules using crossed molecular beams

    SciTech Connect

    Chu, P.M.Y.

    1991-10-01

    The vibrational to translational (V{yields}T) energy transfer in collisions between large highly vibrationally excited polyatomics and rare gases was investigated by time-of-flight techniques. Two different methods, UV excitation followed by intemal conversion and infrared multiphoton excitation (IRMPE), were used to form vibrationally excited molecular beams of hexafluorobenzene and sulfur hexafluoride, respectively. The product translational energy was found to be independent of the vibrational excitation. These results indicate that the probability distribution function for V{yields}T energy transfer is peaked at zero. The collisional relaxation of large polyatomic molecules with rare gases most likely occurs through a rotationally mediated process. Photodissociation of nitrobenzene in a molecular beam was studied at 266 nm. Two primary dissociation channels were identified including simple bond rupture to produce nitrogen dioxide and phenyl radical and isomerization to form nitric oxide and phenoxy radical. The time-of-flight spectra indicate that simple bond rupture and isomerization occurs via two different mechanisms. Secondary dissociation of the phenoxy radicals to carbon monoxide and cyclopentadienyl radicals was observed as well as secondary photodissociation of phenyl radical to give H atom and benzyne. A supersonic methyl radical beam source is developed. The beam source configuration and conditions were optimized for CH{sub 3} production from the thermal decomposition of azomethane. Elastic scattering of methyl radical and neon was used to differentiate between the methyl radicals and the residual azomethane in the molecular beam.

  3. Luminescence and Lasing in ZnSe Micropowders at High Optical Excitation Levels

    NASA Astrophysics Data System (ADS)

    Leanenya, M. S.; Lutsenko, E. V.; Pavlovskii, V. N.; Yablonskii, G. P.; Nagiev, T. G.; Tagiev, B. G.; Tagiev, O. B.; Abushev, S. A.

    2015-03-01

    Photoluminescence (PL) of ZnSe wide-bandgap semiconductor micropowder was studied at a high optical excitation level by pulsed nanosecond N2-laser emission. A new emission band that appeared on the long-wavelength edge of the PL spectrum at 40-75 meV from the electron-hole plasma (EHP) band depending on the optical excitation level showed that plasmons could participate in recombination processes in the EHP. Random lasing at 475 nm from submicron-sized crystallites in ZnSe powder was produced by the third harmonic of a YAG:Nd3+ laser with an exciting-radiation threshold intensity of 750 kW/cm2. The lasing manifested as a sharp increase of integrated emission intensity, a narrowing of the spectrum, and the appearance in it of localized and extended mode structure. Random lasing was due to feedback of amplified radiation in closely packed active scattering microcrystallites.

  4. Low energy nuclear spin excitations in Ho metal investigated by high resolution neutron spectroscopy.

    PubMed

    Chatterji, Tapan; Jalarvo, Niina

    2013-04-17

    We have investigated the low energy excitations in metallic Ho by high resolution neutron spectroscopy. We found at T = 3 K clear inelastic peaks in the energy loss and energy gain sides, along with the central elastic peak. The energy of this low energy excitation, which is 26.59 ± 0.02 μeV at T = 3 K, decreased continuously and became zero at TN ≈ 130 K. By fitting the data in the temperature range 100-127.5 K with a power law we obtained the power-law exponent β = 0.37 ± 0.02, which agrees with the expected value β = 0.367 for a three-dimensional Heisenberg model. Thus the energy of the low energy excitations can be associated with the order parameter. PMID:23507905

  5. Nonlinear vibrations of functionally graded doubly curved shallow shells

    NASA Astrophysics Data System (ADS)

    Alijani, F.; Amabili, M.; Karagiozis, K.; Bakhtiari-Nejad, F.

    2011-03-01

    Nonlinear forced vibrations of FGM doubly curved shallow shells with a rectangular base are investigated. Donnell's nonlinear shallow-shell theory is used and the shell is assumed to be simply supported with movable edges. The equations of motion are reduced using the Galerkin method to a system of infinite nonlinear ordinary differential equations with quadratic and cubic nonlinearities. Using the multiple scales method, primary and subharmonic resonance responses of FGM shells are fully discussed and the effect of volume fraction exponent on the internal resonance conditions, softening/hardening behavior and bifurcations of the shallow shell when the excitation frequency is (i) near the fundamental frequency and (ii) near two times the fundamental frequency is shown. Moreover, using a code based on arclength continuation method, a bifurcation analysis is carried out for a special case with two-to-one internal resonance between the first and second doubly symmetric modes with respect to the panel's center ( ω13≈2 ω11). Bifurcation diagrams and Poincaré maps are obtained through direct time integration of the equations of motion and chaotic regions are shown by calculating Lyapunov exponents and Lyapunov dimension.

  6. Isospin Splittings of Doubly Heavy Baryons

    SciTech Connect

    Brodsky, Stanley J.; Guo, Feng-Kun; Hanhart, Christoph; Meissner, Ulf-G.; /Julich, Forschungszentrum /JCHP, Julich /IAS, Julich /Bonn U., HISKP /Bonn U.

    2011-08-18

    The SELEX Collaboration has reported a very large isospin splitting of doubly charmed baryons. We show that this effect would imply that the doubly charmed baryons are very compact. One intriguing possibility is that such baryons have a linear geometry Q-q-Q where the light quark q oscillates between the two heavy quarks Q, analogous to a linear molecule such as carbon dioxide. However, using conventional arguments, the size of a heavy-light hadron is expected to be around 0.5 fm, much larger than the size needed to explain the observed large isospin splitting. Assuming the distance between two heavy quarks is much smaller than that between the light quark and a heavy one, the doubly heavy baryons are related to the heavy mesons via heavy quark-diquark symmetry. Based on this symmetry, we predict the isospin splittings for doubly heavy baryons including {Xi}{sub cc}, {Xi}{sub bb} and {Xi}{sub bc}. The prediction for the {Xi}{sub cc} is much smaller than the SELEX value. On the other hand, the {Xi}{sub bb} baryons are predicted to have an isospin splitting as large as (6.3 {+-} 1.7) MeV. An experimental study of doubly bottomed baryons is therefore very important to better understand the structure of baryons with heavy quarks.

  7. Intense paramagnon excitations in a large family of high-temperature superconductors

    NASA Astrophysics Data System (ADS)

    Le Tacon, Mathieu

    2012-02-01

    Motivated by the search for the mechanism of high-temperature superconductivity, an intense research effort has been focused on the evolution of the spin excitation spectrum upon doping from the antiferromagnetic insulating to the superconducting states of the cuprates. Because of technical limitations, however, the experimental investigation of doped cuprates has been largely focused on excitations with energies <=100 meV in a small range of momentum space [1]. Here we take advantage of the recent developments of high-resolution resonant inelastic x-ray scattering [2,3] to show that a large family of superconductors, encompassing the model compounds YBa2Cu4O8 and YBa2Cu3O7, exhibits damped spin excitations - or paramagnons - with dispersions and spectral weights closely similar to those of magnons in undoped, antiferromagnetically ordered cuprates over much of the Brillouin zone. The results are in excellent agreement with the spin excitations obtained by exact diagonalization of the t-J Hamiltonian on finite-sized clusters. A numerical solution of the Eliashberg equations based on the experimental spin excitation spectrum of YBa2Cu3O7 reproduces its superconducting transition temperature Tc within a factor of two. The discovery of a well-defined, surprisingly simple spin excitation branch over a wide range of doping levels thus strongly supports magnetic Cooper pairing models for the cuprates [4]. [4pt] [1] M. Fujita et al. arXiv/condmat:1108.4431[0pt] [2] G. Ghiringhelli et al., Review of Scientific Instruments, 77, (2006).[0pt] [3] L. Braicovich et al., Phys. Rev. Lett., 104, 077002 (2010).[0pt] [4] M. Le Tacon et al., Nature Physics 7, 725 (2011).

  8. Application of Excitation from Multiple Locations on a Simplified High-Lift System

    NASA Technical Reports Server (NTRS)

    Melton, LaTunia Pack; Yao, Chung-Sheng; Seifert, Avi

    2004-01-01

    A series of active flow control experiments were recently conducted on a simplified high-lift system. The purpose of the experiments was to explore the prospects of eliminating all but simply hinged leading and trailing edge flaps, while controlling separation on the supercritical airfoil using multiple periodic excitation slots. Excitation was provided by three. independently controlled, self-contained, piezoelectric actuators. Low frequency excitation was generated through amplitude modulation of the high frequency carrier wave, the actuators' resonant frequencies. It was demonstrated, for the first time, that pulsed modulated signal from two neighboring slots interact favorably to increase lift. Phase sensitivity at the low frequency was measured, even though the excitation was synthesized from the high-frequency carrier wave. The measurements were performed at low Reynolds numbers and included mean and unsteady surface pressures, surface hot-films, wake pressures and particle image velocimetry. A modest (6%) increase in maximum lift (compared to the optimal baseline) was obtained due t o the activation of two of the three actuators.

  9. A Spectral Finite Element Approach to Modeling Soft Solids Excited with High-Frequency Harmonic Loads.

    PubMed

    Brigham, John C; Aquino, Wilkins; Aguilo, Miguel A; Diamessis, Peter J

    2011-01-15

    An approach for efficient and accurate finite element analysis of harmonically excited soft solids using high-order spectral finite elements is presented and evaluated. The Helmholtz-type equations used to model such systems suffer from additional numerical error known as pollution when excitation frequency becomes high relative to stiffness (i.e. high wave number), which is the case, for example, for soft tissues subject to ultrasound excitations. The use of high-order polynomial elements allows for a reduction in this pollution error, but requires additional consideration to counteract Runge's phenomenon and/or poor linear system conditioning, which has led to the use of spectral element approaches. This work examines in detail the computational benefits and practical applicability of high-order spectral elements for such problems. The spectral elements examined are tensor product elements (i.e. quad or brick elements) of high-order Lagrangian polynomials with non-uniformly distributed Gauss-Lobatto-Legendre nodal points. A shear plane wave example is presented to show the dependence of the accuracy and computational expense of high-order elements on wave number. Then, a convergence study for a viscoelastic acoustic-structure interaction finite element model of an actual ultrasound driven vibroacoustic experiment is shown. The number of degrees of freedom required for a given accuracy level was found to consistently decrease with increasing element order. However, the computationally optimal element order was found to strongly depend on the wave number. PMID:21461402

  10. A Spectral Finite Element Approach to Modeling Soft Solids Excited with High-Frequency Harmonic Loads

    PubMed Central

    Brigham, John C.; Aquino, Wilkins; Aguilo, Miguel A.; Diamessis, Peter J.

    2010-01-01

    An approach for efficient and accurate finite element analysis of harmonically excited soft solids using high-order spectral finite elements is presented and evaluated. The Helmholtz-type equations used to model such systems suffer from additional numerical error known as pollution when excitation frequency becomes high relative to stiffness (i.e. high wave number), which is the case, for example, for soft tissues subject to ultrasound excitations. The use of high-order polynomial elements allows for a reduction in this pollution error, but requires additional consideration to counteract Runge's phenomenon and/or poor linear system conditioning, which has led to the use of spectral element approaches. This work examines in detail the computational benefits and practical applicability of high-order spectral elements for such problems. The spectral elements examined are tensor product elements (i.e. quad or brick elements) of high-order Lagrangian polynomials with non-uniformly distributed Gauss-Lobatto-Legendre nodal points. A shear plane wave example is presented to show the dependence of the accuracy and computational expense of high-order elements on wave number. Then, a convergence study for a viscoelastic acoustic-structure interaction finite element model of an actual ultrasound driven vibroacoustic experiment is shown. The number of degrees of freedom required for a given accuracy level was found to consistently decrease with increasing element order. However, the computationally optimal element order was found to strongly depend on the wave number. PMID:21461402

  11. Highly charged ion induced nanostructures at surfaces by strong electronic excitations

    NASA Astrophysics Data System (ADS)

    Wilhelm, Richard A.; El-Said, Ayman S.; Krok, Franciszek; Heller, René; Gruber, Elisabeth; Aumayr, Friedrich; Facsko, Stefan

    2015-08-01

    Nanostructure formation by single slow highly charged ion impacts can be associated with high density of electronic excitations at the impact points of the ions. Experimental results show that depending on the target material these electronic excitations may lead to very large desorption yields in the order of a few 1000 atoms per ion or the formation of nanohillocks at the impact site. Even in ultra-thin insulating membranes the formation of nanometer sized pores is observed after ion impact. In this paper, we show recent results on nanostructure formation by highly charged ions and compare them to structures and defects observed after intense electron and light ion irradiation of ionic crystals and graphene. Additional data on energy loss, charge exchange and secondary electron emission of highly charged ions clearly show that the ion charge dominates the defect formation at the surface.

  12. Calculation of specific, highly excited vibrational states based on a Davidson scheme: application to HFCO.

    PubMed

    Iung, Christophe; Ribeiro, Fabienne

    2005-11-01

    We present the efficiency of a new modified Davidson scheme which yields selectively one high-energy vibrationally excited eigenstate or a series of eigenstates. The calculation of a highly vibrationally excited state psi located in a dense part of the spectrum requires a specific prediagonalization step before the Davidson scheme. It consists in building a small active space P containing the zero-order states which are coupled with the zero-order description of the eigenstate of interest. We propose a general way to define this active space P which plays a crucial role in the method. The efficiency of the method is illustrated by computing and analyzing the high-energy excited overtones of the out-of-plane mode [formula: see text] in HFCO. These overtone energies correspond to the 234th, 713th, and 1774th energy levels in our reference basis set which contains roughly 140,000 states. One of the main advantages of this Davidson scheme comes from the fact that the eigenstate and eigenvalue convergence can be assessed during the iterations by looking at the residual [formula: see text]. The maximum value epsilon allowed for this residual constitutes a very sensitive and efficient parameter which sets the accuracy of the eigenvalues and eigenstates, even when the studied states are highly excited and are localized in a dense part of the spectrum. The physical analysis of the eigenstates associated with the 5th, 7th, and 9th out-of-plane overtones in HFCO provides some interesting information on the energy localization in this mode and on the role played by the in-plane modes. Also, it provides some ideas on the numerical methods which should be developed in the future to tackle higher-energy excited states in polyatomics. PMID:16375515

  13. Current status of free radicals and electronically excited metastable species as high energy propellants

    NASA Technical Reports Server (NTRS)

    Rosen, G.

    1973-01-01

    A survey is presented of free radicals and electronically excited metastable species as high energy propellants for rocket engines. Nascent or atomic forms of diatomic gases are considered free radicals as well as the highly reactive diatomic triatomic molecules that posess unpaired electrons. Manufacturing and storage problems are described, and a review of current experimental work related to the manufacture of atomic hydrogen propellants is presented.

  14. A proposal for fs-electron microscopy experiments on high-energy excitations in solids.

    PubMed

    Piazza, L; Musumeci, P; Luiten, O J; Carbone, Fabrizio

    2014-08-01

    Recent advances in ultrafast technology enable both the study and the control of materials properties thanks to the ability to record high temporal resolution movies of their transformations, or the ability to generate new states of matter by selecting ad hoc an excitation to drive the system out of equilibrium. The holy grail of this type of experiments is to combine a high tuneability of the excitation with a wide observation window. For example, this is achieved in multidimensional optical spectroscopy where the response to several excitation energies is monitored in a broad energy range by a large bandwidth optical pulse. In this article, the possibility to combine the chemical sensitivity of intense tuneable X-rays pulses from a free electron laser, with the wide range of observables available in an ultrafast transmission electron microscope is discussed. The requirements for such experiments are quantified via estimates based on state of the art experiments and simulations, and it is proposed that ultrafast electron imaging, diffraction and spectroscopy experiments can be performed in combination with a chemically selective X-ray excitation of materials. PMID:24631423

  15. Communication: excitation band modulation with high-order photonic band gap in PMMA:Eu(TTA)3(TPPO)2 opals.

    PubMed

    Xu, Wen; Bai, Xue; Zhu, Yongsheng; Liu, Tong; Xu, Sai; Dong, Biao; Song, Hongwei

    2013-05-14

    Changes in the excitation spectra of luminescent species inserted in photorefractive crystals as a function of changes in the high-order photonic band gap (PBG) have not been previously observed. In this communication, we present our results monitoring the excitation band of Eu(TTA)3(TPPO)2 inserted in the PMMA opal photonic crystals as a function of the changes in the high-order PBG of the crystals. We find shifts in the complex excitation band and changes in the integrated emission intensity that correlates with shifts in the high-order PBG through coupling to the excitation transition. PMID:23676019

  16. Communication: Excitation band modulation with high-order photonic band gap in PMMA:Eu(TTA)3(TPPO)2 opals

    NASA Astrophysics Data System (ADS)

    Xu, Wen; Bai, Xue; Zhu, Yongsheng; Liu, Tong; Xu, Sai; Dong, Biao; Song, Hongwei

    2013-05-01

    Changes in the excitation spectra of luminescent species inserted in photorefractive crystals as a function of changes in the high-order photonic band gap (PBG) have not been previously observed. In this communication, we present our results monitoring the excitation band of Eu(TTA)3(TPPO)2 inserted in the PMMA opal photonic crystals as a function of the changes in the high-order PBG of the crystals. We find shifts in the complex excitation band and changes in the integrated emission intensity that correlates with shifts in the high-order PBG through coupling to the excitation transition.

  17. Highly efficient terahertz wave modulators by photo-excitation of organics/silicon bilayers

    SciTech Connect

    Yoo, Hyung Keun; Kang, Chul; Hwang, In-Wook; Yoon, Youngwoon; Lee, Kiejin; Kee, Chul-Sik; Lee, Joong Wook

    2014-07-07

    Using hybrid bilayer systems comprising a molecular organic semiconductor and silicon, we achieve optically controllable active terahertz (THz) modulators that exhibit extremely high modulation efficiencies. A modulation efficiency of 98% is achieved from thermally annealed C{sub 60}/silicon bilayers, due to the rapid photo-induced electron transfer from the excited states of the silicon onto the C{sub 60} layer. Furthermore, we demonstrate the broadband modulation of THz waves. The cut-off condition of the system that is determined by the formation of efficient charge separation by the photo-excitation is highly variable, changing the system from insulating to metallic. The phenomenon enables an extremely high modulation bandwidth and rates of electromagnetic waves of interest. The realization of near-perfect modulation efficiency in THz frequencies opens up the possibilities of utilizing active modulators for THz spectroscopy and communications.

  18. Excitation into high-lying states in Li3+–H collisions

    NASA Astrophysics Data System (ADS)

    Ibaaz, Aicha; Esteban Hernandez, Rosa; Dubois, Alain; Sisourat, Nicolas

    2016-04-01

    We have studied the excitation of atomic hydrogen by fully-stripped lithium ion impact in the intermediate energy range using a new and efficient implementation of the two-center atomic orbital approach with Gaussian-type orbitals. Partial and state-selective cross sections have been obtained for excitation up to H(6 h). A careful investigation of the convergence of the results with respect to the basis set has been performed which allows us to estimate the accuracy of the cross sections. Furthermore, our calculations provide an explanation for the discrepancies between previous calculations on this collision system.

  19. Highly correlated systems. Excitation energies of first row transition metals Sc--Cu

    SciTech Connect

    Raghavachari, K.; Trucks, G. W.

    1989-07-15

    The low-lying /ital d//sup /ital n/s//sup 2//r arrow//ital d//sup /ital n/+1//ital s//sup 1/ excitation energies of the first row transition metal atoms Sc--Cu are calculated using fourth-order M/congruent/ller--Plesset perturbation theory (MP4) as well as quadratic configuration interaction (QCI) techniques with large /ital spd/ and /ital spdf/ basis sets. The MP4 method performs well for Sc--Mn but fails dramatically for Fe--Cu. In contrast, the QCI technique performs uniformly for all excitation energies with a mean deviation from experiment of only 0.14 eV after including relativistic corrections. /ital f/ functions contribute 0.1--0.4 eV to the excitation energies for these systems. The highly correlated /ital d//sup 10/ state of the Ni atom is also considered in detail. The QCI technique obtains the /ital d//sup 9//ital s1//r arrow//ital d10/ splitting of the Ni atom with an error of only 0.13 eV. The results show that single-configuration Hartree--Fock based methods can be successful in calculating excitation energies of transition metal atoms.

  20. Nonthermal Optical Emission Spectrometry: Direct Atomization and Excitation of Cadmium for Highly Sensitive Determination.

    PubMed

    Cai, Yi; Zhang, Ya-Jie; Wu, De-Fu; Yu, Yong-Liang; Wang, Jian-Hua

    2016-04-19

    The low atomization and excitation capability of nonthermal microplasma, e.g., dielectric barrier discharge (DBD), has greatly hampered its potential applications for the determination of metals in solution. In the present work, an inspiring development is reported for direct atomization and excitation of cadmium in aqueous solution by DBD and facilitates highly sensitive determination. A DBD microplasma is generated on the nozzle of a pneumatic micronebulizer to focus the DBD energy on a confined space and atomize/excite metals in the spray. Meanwhile, an appropriate sample matrix and nebulization in helium further improves the atomization and excitation capability of DBD. With cadmium as a model, its emission is recorded by a CCD spectrometer at 228.8 nm. By using an 80 μL sample solution nebulized at 3 μL s(-1), a linear range of 5-1000 μg L(-1) along with a detection limit of 1.5 μg L(-1) is achieved, which is comparable to those obtained by commercial bulky inductively coupled plasma (ICP)-based instrumentations. PMID:27030025

  1. Spin orbit coupling induced splitting in excitations of high mobility 2DESs

    NASA Astrophysics Data System (ADS)

    Rigosi, Albert F.; Wurstbauer, Ursula; Pinczuk, Aron; Watson, John; Mondal, Sumit; Manfra, Michael J.; West, Ken W.; Pfeiffer, Loren N.

    2012-02-01

    Spin orbit interaction (SOI) induces a splitting of the conduction bands in two-dimensional electron systems (2DES) in GaAs. We study the impact of zero-field spin-splitting on excitations of ultra high mobility 2DESs by resonant inelastic light scattering experiments. To distinguish between splitting caused by bulk inversion asymmetry (Dresselhaus) and structure inversion asymmetry (Rashba), we studied symmetric (two-side modulation doped) and asymmetric (single-side modulation doped) quantum wells grown along (001) and (110) crystallographic directions. We probe the excitation modes as a function of transferred momentum for different crystallographic directions in the plane of the QW. At large wave vectors we find a complex splitting of the single-particle intersubband excitation mode that is strongly dependent on the combination of Dresselhaus and Rashba SOI. The observed mode splitting is a result of effective SOI fields in both, ground and first excited subband. Suitable choices of crystallographic orientations yield Dresselhaus and Rashba terms.

  2. Stand-Alone Front-End System for High-Frequency, High-Frame-Rate Coded Excitation Ultrasonic Imaging

    PubMed Central

    Park, Jinhyoung; Hu, Changhong; Shung, K. Kirk

    2012-01-01

    A stand-alone front-end system for high-frequency coded excitation imaging was implemented to achieve a wider dynamic range. The system included an arbitrary waveform amplifier, an arbitrary waveform generator, an analog receiver, a motor position interpreter, a motor controller and power supplies. The digitized arbitrary waveforms at a sampling rate of 150 MHz could be programmed and converted to an analog signal. The pulse was subsequently amplified to excite an ultrasound transducer, and the maximum output voltage level achieved was 120 Vpp. The bandwidth of the arbitrary waveform amplifier was from 1 to 70 MHz. The noise figure of the preamplifier was less than 7.7 dB and the bandwidth was 95 MHz. Phantoms and biological tissues were imaged at a frame rate as high as 68 frames per second (fps) to evaluate the performance of the system. During the measurement, 40-MHz lithium niobate (LiNbO3) single-element lightweight (<0.28 g) transducers were utilized. The wire target measurement showed that the −6-dB axial resolution of a chirp-coded excitation was 50 µm and lateral resolution was 120 µm. The echo signal-to-noise ratios were found to be 54 and 65 dB for the short burst and coded excitation, respectively. The contrast resolution in a sphere phantom study was estimated to be 24 dB for the chirp-coded excitation and 15 dB for the short burst modes. In an in vivo study, zebrafish and mouse hearts were imaged. Boundaries of the zebrafish heart in the image could be differentiated because of the low-noise operation of the implemented system. In mouse heart images, valves and chambers could be readily visualized with the coded excitation. PMID:23443698

  3. Persistence of magnetic order in a highly excited Cu2+ state in CuO

    NASA Astrophysics Data System (ADS)

    Staub, U.; de Souza, R. A.; Beaud, P.; Möhr-Vorobeva, E.; Ingold, G.; Caviezel, A.; Scagnoli, V.; Delley, B.; Turner, J. J.; Krupin, O.; Lee, W.-S.; Chuang, Y.-D.; Patthey, L.; Moore, R. G.; Lu, D.; Yi, M.; Kirchmann, P. S.; Trigo, M.; Denes, P.; Doering, D.; Hussain, Z.; Shen, Z. X.; Prabhakaran, D.; Boothroyd, A. T.; Johnson, S. L.

    2014-06-01

    We use ultrafast resonant x-ray diffraction to study the magnetic order in CuO under conditions of high electronic excitation. By measuring changes in the spectral shape of the Cu2+ magnetic (1/2 0 -1/2) reflection we investigate how an intense optical pump pulse perturbs the electronic and magnetic states. We observe an energy shift in the magnetic resonance at short times after the pump pulse. This shift is compared with expectations from band structure calculations at different electronic temperatures. This spectral line shift indicates that although the electrons are heated to effective electron temperatures far above TN on a time scale faster than the experimental resolution, magnetic order persists in this highly excited state for several hundred femtoseconds.

  4. The Complex Environment of the High Excitation Planetary Nebula NGC 3242

    NASA Technical Reports Server (NTRS)

    Noriega-Crespo, A.; Meaburn, J.; Lopez, J.

    1999-01-01

    Spatially resolved profiles of the H (alpha), [N II] 6584 A and [O III] 5007 A nebular emission lines, obtained with the Manchester echelle spectrometer combined with the 2.1 m San Pedro Martir telescope have revealed the velocity structure of the nebular core and of one of the three (A,B and C) inner haloes of the high excitation planetary nebula NGC 3242.

  5. The role of excitation parameters in high repetition-rate N2-TE lasers

    NASA Astrophysics Data System (ADS)

    Kukhlevsky, S. V.; Kozma, L.

    1993-09-01

    We have studied the effects of decreasing the excitation duration on the pulse-repetition-rate (PRR) capabilities of a low-pressure ( P<200 Torr) N2-TE laser. It was found that maximum PRR increases with decreasing duration of the discharge current. PRR as high as 1000 Hz has been obtained in the sealed-off non-flowing regime of laser operation. These findings are adequately explained by the time dependence of the arc-discharge formation.

  6. Novel magnetic excitations in a model cuprate high-Tc superconductor

    NASA Astrophysics Data System (ADS)

    Li, Yuan

    2011-03-01

    Magnetic fluctuations might be essential to the mechanism of high-temperature superconductivity in the cuprates. For a long time, such fluctuations have been theoretically regarded as arising from the antiferromagnetic correlations within the copper-oxygen layers, and experimental studies of magnetic excitation spectrum have mainly been carried out near the corresponding wave vector (1/2,~1/2). Following neutron diffraction experiments which demonstrated the universal existence of a `` q ~=~0 antiferromagnetic order'' in the pseudogap phase of three different cuprates [1-3], our recent inelastic neutron scattering experiments on the model compound HgBa 2 Cu O4 + δ (Hg1201) revealed the existence of unusual magnetic excitations that weakly disperse throughout the entire Brillouin zone [4,5]. Like the q ~=~0 antiferromagnetic order, the new excitations are observed in the pseudogap phase and therefore appear to be associated with the order. The excitations possess very large spectral weights at well-defined characteristic energies that are comparable to the resonance energy and to those of electron-boson-coupling features observed in a wide range of cuprates, highlighting their possible influence on the electronic structure. These findings demonstrate that the pseudogap state is a distinct phase of matter rather than a mere crossover. They furthermore cast doubt on the presumed predominant importance of the wave vector (1/2,~1/2) in the magnetic excitation spectrum, and have the profound implication that a single-band description of the cuprates is insufficient. Project was funded by DOE and NSF grants. The author achnowledges the Alexander von Humboldt Foundation.

  7. Two-Component Structure in the Entanglement Spectrum of Highly Excited States.

    PubMed

    Yang, Zhi-Cheng; Chamon, Claudio; Hamma, Alioscia; Mucciolo, Eduardo R

    2015-12-31

    We study the entanglement spectrum of highly excited eigenstates of two known models that exhibit a many-body localization transition, namely the one-dimensional random-field Heisenberg model and the quantum random energy model. Our results indicate that the entanglement spectrum shows a "two-component" structure: a universal part that is associated with random matrix theory, and a nonuniversal part that is model dependent. The nonuniversal part manifests the deviation of the highly excited eigenstate from a true random state even in the thermalized phase where the eigenstate thermalization hypothesis holds. The fraction of the spectrum containing the universal part decreases as one approaches the critical point and vanishes in the localized phase in the thermodynamic limit. We use the universal part fraction to construct an order parameter for measuring the degree of randomness of a generic highly excited state, which is also a promising candidate for studying the many-body localization transition. Two toy models based on Rokhsar-Kivelson type wave functions are constructed and their entanglement spectra are shown to exhibit the same structure. PMID:26765022

  8. Study of M1 and E1 excitations by high-resolution proton inelastic scattering measurement at forward angles

    SciTech Connect

    Tamii, A.; Adachi, T.; Hatanaka, K.; Hashimoto, H.; Kaneda, T.; Matsubara, H.; Okamura, H.; Sakemi, Y.; Shimizu, Y.; Tameshige, Y.; Yosoi, M.; Carter, J.; Dozono, M.; Fujita, H.; Fujita, Y.; Itoh, M.; Kawabata, T.; Nakanishi, K.; Sasamoto, Y.; Neumann-Cosel, P. von

    2007-06-13

    Experimental technique for measuring proton inelastic scattering with high-resolution at 295 MeV and at forward angles including zero degrees is described. The method is useful for extracting spin part of the M1 strength via nuclear excitation as well as E1 strength via Coulomb excitation. An excitation energy resolution of 20 keV, good scattering angle resolution, and low background condition have been achieved. The experimental technique was applied for several sd and pf shell nuclei.

  9. Long-term spectroscopy of η Carinae. I. The high and low excitation phases

    NASA Astrophysics Data System (ADS)

    Damineli, A.; Stahl, O.; Kaufer, A.; Wolf, B.; Quast, G.; Lopes, D. F.

    1998-12-01

    Quantitative measurements of line parameters in the spectrum of η Carinae are presented for both the broad and narrow line components. A total of 655 spectral features were measured in the spectral range 3850 Angstroms to 11000 Angstroms, giving a comprehensive view of the behavior of atomic transitions ranging from a few to tens of electron volts. The spectrum on the phase of maximum intensity in the high excitation lines (1995) is compared with that on minimum intensity (June 1992), showing that at this phase the high excitation lines disappear but the broad components of low excitation lines strengthens. We reject a number of previous line identifications and propose several new ones, including Fe II, [Fe II], [Fe III], [N II], and the near-infrared Ca II triplet. Some lines commonly used to diagnose density, temperature, chemical composition, and reddening were found to be blended, urging a revision of the results based on previous data. The existence of double-peaked lines, suggested in previous papers, is ruled out. In the case of hydrogen lines, the apparent double-peaks are shown to be real absorption components. The velocity field in the inner 2 arcsec around the central star shows additional components previously unknown. The phases of high and low excitation in η Carinae are discussed in light of a recently proposed binary system. We suggest a temperature T ~ 16000 K for the primary star, what indicates that it is close to the beginning of the core helium-burning evolutionary stage. Based on data collected at European Southern Observatory and Laboratorio Nacional de Astrofisica. Table 1 is only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/Abstract.html

  10. Synthesis and Metalation of Doubly o-Phenylene-Bridged Cyclic Bis(dipyrrin)s with Highly Bent Skeleton of Dibenzoporphyrin(2.1.2.1).

    PubMed

    Kuzuhara, Daiki; Furukawa, Wataru; Kitashiro, Aya; Aratani, Naoki; Yamada, Hiroko

    2016-07-18

    Facile synthesis of dibenzoporphyrins(2.1.2.1) has been successfully reported by the simple condensation reaction of o-dipyrrolylbenzene with various aldehydes in the presence of a Lewis acid. This reaction enables the preparation of various dibenzoporphyrin(2.1.2.1) derivatives with p-substituted phenyl groups, five-membered heterocycles, and ethynyl groups at the meso-positions. Dibenzoporphyrins(2.1.2.1) consist of two dipyrrin units that are connected by o-phenylene bridges, which adopt highly bent saddle-shaped structures; this was confirmed by X-ray diffraction analysis. We found that dibenzoporphyrin(2.1.2.1) can be described as a 20π antiaromatic conjugated system, but practically, it is not an antiaromatic macrocycle, which we revealed by (1) H NMR spectroscopy. The redox potentials had good correlations with Hammett substituent constant (σp ) of the substituents at the meso-positions. The free-base dibenzoporphyrin(2.1.2.1) was able to form the metal complexes with nickel(II), copper(II), palladium(II), platinum(II), and tin(IV) ions. These results suggested that dibenzoporphyrin(2.1.2.1) derivatives can be utilized as novel macrocyclic dianionic tetradentate ligands for various metal ions to give complexes with varying optical and electrochemical properties. PMID:27346804

  11. High-energy electronic excitations in Sr2IrO4 observed by Raman scattering

    NASA Astrophysics Data System (ADS)

    Yang, Jhih-An; Huang, Yi-Ping; Hermele, Michael; Qi, Tongfei; Cao, Gang; Reznik, Dmitry

    2015-03-01

    The interplay between spin-orbit interaction, on-site coulomb correlation, crystal field splitting, and inter-site hopping leads to a novel insulating behavior in Sr2IrO4 as the realization of the Jeff = 1 / 2 state. We report results of a large-shift Raman scattering investigation of electronic excitations in Sr2IrO4. We found two high-energy excitations at 690 meV and 680 meV with A1 g and B1 g symmetry respectively. The two peaks have different temperature and Rh-doping dependences. Symmetry analysis of the dd transitions that contribute to Raman signals will also be presented. The observed peaks are consistent with the scenario of excitons associated with inter-site dd transitions without pseudospin-flip. NSF, DOE, and BES.

  12. Dynamic modification of the fragmentation of COq+ excited states generated with high-order harmonics

    NASA Astrophysics Data System (ADS)

    Cao, W.; de, S.; Singh, K. P.; Chen, S.; Schöffler, M. S.; Alnaser, A. S.; Bocharova, I. A.; Laurent, G.; Ray, D.; Zherebtsov, S.; Kling, M. F.; Ben-Itzhak, I.; Litvinyuk, I. V.; Belkacem, A.; Osipov, T.; Rescigno, T.; Cocke, C. L.

    2010-10-01

    The dynamic process of fragmentation of COq+ excited states is investigated using a pump-probe approach. EUV radiation (32-48 eV) generated by high-order harmonics was used to ionize and excite CO molecules and a time-delayed infrared (IR) pulse (800 nm) was used to influence the evolution of the dissociating multichannel wave packet. Two groups of states, separable experimentally by their kinetic-energy release (KER), are populated by the EUV and lead to C+-O+ fragmentation: direct double ionization of the neutral molecule and fragmentation of the cation leading to C+-O*, followed by autoionization of O*. The IR pulse was found to modify the KER of the latter group in a delay-dependent way which is explained with a model calculation.

  13. Equation-of-motion coupled cluster method for the description of the high spin excited states.

    PubMed

    Musiał, Monika; Lupa, Łukasz; Kucharski, Stanisław A

    2016-04-21

    The equation-of-motion (EOM) coupled cluster (CC) approach in the version applicable for the excitation energy(EE) calculations has been formulated for high spin components. The EE-EOM-CC scheme based on the restricted Hartree-Fock reference and standard amplitude equations as used in the Davidson diagonalization procedure yields the singlet states. The triplet and higher spin components require separate amplitude equations. In the case of quintets, the relevant equations are much simpler and easier to solve. Out of 26 diagrammatic terms contributing to the R1 and R2 singlet equations in the case of quintets, only R2 operator survives with 5 diagrammatic terms present. In addition all terms engaging three body elements of the similarity transformed Hamiltonian disappear. This indicates a substantial simplification of the theory. The implemented method has been applied to the pilot study of the excited states of the C2 molecule and quintet states of C and Si atoms. PMID:27389207

  14. Wavelength selective excitation of surface oxygen anions on highly dispersed MgO

    NASA Astrophysics Data System (ADS)

    Diwald, Oliver; Sterrer, Martin; Knözinger, Erich; Sushko, Peter V.; Shluger, Alexander L.

    2002-01-01

    Monochromatic UV light in the spectral interval between 4.0 and 5.5 eV is used in order to selectively excite 3- and 4-coordinated oxygen anion sites on the surface of MgO nanoparticles exposed to O2 gas. As a result, two different paramagnetic O- surface species and also ozonide anions O3- are observed by electron paramagnetic resonance (EPR) spectroscopy. The relative abundance of each of the O- species exhibits a specific dependence on the energy of the exciting photons. EPR data together with the results of theoretical modeling suggest that both O- species are located at 3-coordinated sites having different local environments. At sufficiently high O2 pressures molecular oxygen does not only act as an electron trap, favoring the O- formation, but it also contributes to UV induced O3- formation with a maximum efficiency at 4.2 eV.

  15. Energy shift of collective electron excitations in highly corrugated graphitic nanostructures: Experimental and theoretical investigation

    NASA Astrophysics Data System (ADS)

    Sedelnikova, O. V.; Bulusheva, L. G.; Asanov, I. P.; Yushina, I. V.; Okotrub, A. V.

    2014-04-01

    Effect of corrugation of hexagonal carbon network on the collective electron excitations has been studied using optical absorption and X-ray photoelectron spectroscopy in conjunction with density functional theory calculations. Onion-like carbon (OLC) was taken as a material, where graphitic mantle enveloping agglomerates of multi-shell fullerenes is strongly curved. Experiments showed that positions of π and π + σ plasmon modes as well as π → π* absorption peak are substantially redshifted for OLC as compared with those of highly ordered pyrolytic graphite and thermally exfoliated graphite consisted of planar sheets. This effect was reproduced in behavior of dielectric functions of rippled graphite models calculated within the random phase approximation. We conclude that the energy of electron excitations in graphitic materials could be precisely tuned by a simple bending of hexagonal network without change of topology. Moreover, our investigation suggests that in such materials optical exciton can transfer energy to plasmon non-radiatively.

  16. Equation-of-motion coupled cluster method for the description of the high spin excited states

    NASA Astrophysics Data System (ADS)

    Musiał, Monika; Lupa, Łukasz; Kucharski, Stanisław A.

    2016-04-01

    The equation-of-motion (EOM) coupled cluster (CC) approach in the version applicable for the excitation energy (EE) calculations has been formulated for high spin components. The EE-EOM-CC scheme based on the restricted Hartree-Fock reference and standard amplitude equations as used in the Davidson diagonalization procedure yields the singlet states. The triplet and higher spin components require separate amplitude equations. In the case of quintets, the relevant equations are much simpler and easier to solve. Out of 26 diagrammatic terms contributing to the R1 and R2 singlet equations in the case of quintets, only R2 operator survives with 5 diagrammatic terms present. In addition all terms engaging three body elements of the similarity transformed Hamiltonian disappear. This indicates a substantial simplification of the theory. The implemented method has been applied to the pilot study of the excited states of the C2 molecule and quintet states of C and Si atoms.

  17. Highly selective population of two excited states in nonresonant two-photon absorption

    NASA Astrophysics Data System (ADS)

    Zhang, Hui; Zhang, Shi-An; Sun, Zhen-Rong

    2011-08-01

    A nonresonant two-photon absorption process can be manipulated by tailoring the ultra-short laser pulse. In this paper, we theoretically demonstrate a highly selective population of two excited states in the nonresonant two-photon absorption process by rationally designing a spectral phase distribution. Our results show that one excited state is maximally populated while the other state population is widely tunable from zero to the maximum value. We believe that the theoretical results may play an important role in the selective population of a more complex nonlinear process comprising nonresonant two-photon absorption, such as resonance-mediated (2+1)-three-photon absorption and (2+1)-resonant multiphoton ionization.

  18. Energy shift of collective electron excitations in highly corrugated graphitic nanostructures: Experimental and theoretical investigation

    SciTech Connect

    Sedelnikova, O. V. Bulusheva, L. G.; Okotrub, A. V.; Asanov, I. P.; Yushina, I. V.

    2014-04-21

    Effect of corrugation of hexagonal carbon network on the collective electron excitations has been studied using optical absorption and X-ray photoelectron spectroscopy in conjunction with density functional theory calculations. Onion-like carbon (OLC) was taken as a material, where graphitic mantle enveloping agglomerates of multi-shell fullerenes is strongly curved. Experiments showed that positions of π and π + σ plasmon modes as well as π → π* absorption peak are substantially redshifted for OLC as compared with those of highly ordered pyrolytic graphite and thermally exfoliated graphite consisted of planar sheets. This effect was reproduced in behavior of dielectric functions of rippled graphite models calculated within the random phase approximation. We conclude that the energy of electron excitations in graphitic materials could be precisely tuned by a simple bending of hexagonal network without change of topology. Moreover, our investigation suggests that in such materials optical exciton can transfer energy to plasmon non-radiatively.

  19. Resonance Excitation of Longitudinal High Order Modes in Project X Linac

    SciTech Connect

    Khabiboulline, T.N.; Sukhanov, A.AUTHOR = Awida, M.; Gonin, I.; Lunin, A.AUTHOR = Solyak, N.; Yakovlev, V.; /Fermilab

    2012-05-01

    Results of simulation of power loss due to excitation of longitudinal high order modes (HOMs) in the accelerating superconducting RF system of CW linac of Project X are presented. Beam structures corresponding to the various modes of Project X operation are considered: CW regime for 3 GeV physics program; pulsed mode for neutrino experiments; and pulsed regime, when Project X linac operates as a driver for Neutrino Factory/Muon Collider. Power loss and associated heat load due to resonance excitation of longitudinal HOMs are shown to be small in all modes of operation. Conclusion is made that HOM couplers can be removed from the design of superconducting RF cavities of Project X linac.

  20. Center mode of a doubly resonant optical periodic structure

    NASA Astrophysics Data System (ADS)

    Alagappan, G.; Png, C. E.

    2016-07-01

    An optical periodic structure with a single spatial resonance exhibits a stopband. When a second spatial resonance very close to the first one is added, the resulting doubly resonant structure exhibits a Gaussian enveloped, high quality factor transmission state right at the center of the original stopband. Using a slowly varying envelope approximation, we describe the optical characteristics of this transmission state analytically. The transmission state exists despite an optical structure of low refractive index contrast, and has potential applications in nano-optics, and photonics.

  1. Precision Spectroscopy on Highly-Excited Vibrational Levels of H_2

    NASA Astrophysics Data System (ADS)

    Niu, Ming Li; Salumbides, Edcel John; Ubachs, Wim

    2015-06-01

    The ground electronic energy levels of H_2 have been used as a benchmark system for the most precise comparisons between ab initio calculations and experimental investigations. Recent examples include the determinations of the ionization energy [1], fundamental vibrational energy splitting [2], and rotational energy progression extending to J=16 [3]. In general, the experimental and theoretical values are in excellent agreement with each other. The energy calculations, however, reduce in accuracy with the increase in rotational and vibrational excitation, limited by the accuracy of non-Born Oppenheimer corrections, as well as the higher-order QED effects. While on the experimental side, it remains difficult to sufficiently populate these excited levels in the ground electronic state. We present here our high-resolution spectroscopic study on the X ^1σ^+_g electronic ground state levels with very high vibrational quanta (ν=10,11,12). Vibrationally-excited H_2 are produced from the photodissociation of H_2S [4], and subsequently probed by a narrowband pulsed dye laser system. The experimental results are consistent with and more accurate than the best theoretical values [5]. These vibrationally-excited level energies are also of interest to studies that extract constraints on the possible new interactions that extend beyond the Standard Model [6]. [1] J. Liu et al., J. Chem. Phys. 130, 174306 (2009). [2] G. Dickenson et al., Phys. Rev. Lett. 110, 193601 (2013). [3] E.J. Salumbides et al., Phys. Rev. Lett. 107, 143005 (2011). [4] J. Steadman and T. Baer, J. Chem. Phys. 91, 6113 (1989). [5] J. Komasa et al., J. Chem. Theory Comp. 7, 3105 (2011). [6] E.J. Salumbides et al., Phys. Rev. D 87, 112008 (2013).

  2. An impact excitation system for repeatable, high-bandwidth modal testing of miniature structures

    NASA Astrophysics Data System (ADS)

    Bediz, Bekir; Korkmaz, Emrullah; Burak Ozdoganlar, O.

    2014-06-01

    Miniature components and devices are increasingly seen in a myriad of applications. In general, the dynamic behavior of miniature devices is critical to their functionality and performance. However, modal testing of miniature structures poses many challenges. This paper presents a design and evaluation of an impact excitation system (IES) for repeatable, high-bandwidth, controlled-force modal testing of miniature structures. Furthermore, a dynamic model of the system is derived and experimentally validated to enable the identification of the system parameters that yield single-hit impacts with desired bandwidth and force magnitude. The system includes a small instrumented impact tip attached to a custom designed flexure-based body, an automated electromagnetic release mechanism, and various precision positioners. The excitation bandwidth and the impact force magnitude can be controlled by selecting the system parameters. The dynamic model of the system includes the structural dynamics of the flexure-based body, the electromagnetic force and the associated eddy-current damping, and the impact event. A validation study showed an excellent match between the model simulations and experiments in terms of impact force and bandwidth. The model is then used to create process maps that relate the system parameters to the number of hits (single vs. multiple), the impact force magnitudes and the excitation bandwidths. These process maps can be used to select system parameters or predict system response for a given set of parameters. A set of experiments is conducted to compare the performances of the IES and a (manual) miniature impact hammer. It is concluded that the IES significantly improves repeatability in terms of the impact bandwidth, location, and force magnitude, while providing a high excitation-bandwidth and excellent coherence values. The application of the IES is demonstrated through modal testing of a miniature contact-probe system.

  3. Study of highly excited string states at the Large Hadron Collider

    SciTech Connect

    Gingrich, Douglas M.; Martell, Kevin

    2008-12-01

    In TeV-scale gravity scenarios with large extra dimensions, black holes may be produced at future colliders. Good arguments have been made for why general relativistic black holes may be just out of reach of the Large Hadron Collider (LHC). However, in weakly coupled string theory, highly excited string states--string balls--could be produced at the LHC with high rates and decay thermally, not unlike general relativistic black holes. In this paper, we simulate and study string ball production and decay at the LHC. We specifically emphasize the experimentally detectable similarities and differences between string balls and general relativistic black holes at a TeV scale.

  4. Torus quantization of symmetrically excited helium

    SciTech Connect

    Mueller, J. ); Burgdoerfer, J. Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6377 ); Noid, D. )

    1992-02-01

    The recent discovery by Richter and Wintgen (J. Phys. B 23, L197 (1990)) that the classical helium atom is not globally ergodic has stimulated renewed interest in its semiclassical quantization. The Einstein-Brillouin-Keller quantization of Kolmogorov-Arnold-Moser tori around stable periodic orbits becomes locally possible in a selected region of phase space. Using a hyperspherical representation we have found a dynamically confining potential allowing for a stable motion near the Wannier ridge. The resulting semiclassical eigenenergies provide a test for full quantum calculations in the limit of very high quantum numbers. The relations to frequently used group-theoretical classifications for doubly excited states and to the periodic-orbit quantization of the chaotic portion of the phase space are discussed. The extrapolation of the semiclassical quantization to low-lying states give remarkably accurate estimates for the energies of all symmetric {ital L}=0 states of helium.

  5. Discordance of the unified scheme with observed properties of quasars and high-excitation galaxies in the 3CRR sample

    SciTech Connect

    Singal, Ashok K.

    2014-07-01

    We examine the consistency of the unified scheme of Fanaroff-Riley type II radio galaxies and quasars with their observed number and size distributions in the 3CRR sample. We separate the low-excitation galaxies from the high-excitation ones, as the former might not harbor a quasar within and thus may not be partaking in the unified scheme models. In the updated 3CRR sample, at low redshifts (z < 0.5), the relative number and luminosity distributions of high-excitation galaxies and quasars roughly match the expectations from the orientation-based unified scheme model. However, a foreshortening in the observed sizes of quasars, which is a must in the orientation-based model, is not seen with respect to radio galaxies even when the low-excitation galaxies are excluded. This dashes the hope that the unified scheme might still work if one includes only the high-excitation galaxies.

  6. Surface modification of monocrystalline zinc oxide induced by high-density electronic excitation

    NASA Astrophysics Data System (ADS)

    Museur, Luc; Manousaki, Alexandra; Anglos, Demetrios; Kanaev, Andrei V.

    2011-12-01

    Strong modifications of semiconductors can be provoked by high-density electronic excitation. We report on surface structuring of monocrystalline wurtzite O-face (0001) ZnO excited by UV femtosecond laser pulses (248 nm) below the ablation threshold. At fluences above 11 mJ/cm2, nanoholes of D=10 nm diameter appear quasi-periodically separated by a distance ˜30 nm (=3 D). Dual-pulse (pump-pump) experiments permit estimation of the electronic excitation lifetime responsible for this nanostructuring, which is in agreement with the electron-hole plasma lifetime 220 ps. The nanostructuring results in a smaller monocrystalline domain of ˜0.1 μm size and increases the crystalline interplane c-distance by 0.11%. The excitonic luminescence of the irradiated sample is found to increase by about 10 times. The nanostructuring remains stable in a limited range of laser fluences: above 40 mJ/cm2 the surface melts, which accelerates the photoinduced bonds breaking leading to surface erosion. We tentatively ascribe the related mechanism to the nucleation-growth of cluster vacancies at crystal dislocations accelerated by the non-thermal (electronic) melting of the surface layer. At fluences lower than 11 mJ/cm2, larger volcano-like features of 60-nm diameter were observed. The characteristic crater shape and irregular surface repartition permit their assignment to thermal explosion of impurities due to multiple exciton condensation.

  7. Thermal and Mechanical Response of PBX 9501 and Simulants Under High Frequency Contact Excitation

    NASA Astrophysics Data System (ADS)

    Mares, Jesus Ortega, Jr.

    Stand-off detection of explosives through trace vapor detection remains a distinct challenge due to the low vapor pressures of these materials. However, it is known that the vapor concentration of these explosives may be significantly increased by elevating the temperature of the material. It is plausible that improvements in the detection of explosives might be realized through the use of mechanical excitation. In this work PBX 9501 (an HMX-based explosive), two mechanical mock materials 900-21, and PBS 9501 were insulted with contact mechanical excitation in the frequency range of 50 kHz to 40 MHz. The mechanical response of each sample was measured via ultrasound transducers and was confirmed via laser Doppler vibrometry up to a frequency of 1 MHz. Steady-state thermal responses were observed via infrared thermography at discrete frequencies spanning the full frequency range of interest. Temperature excursions of approximately 15 K were observed in PBX 9501 and similar results were observed from the mock materials. The mechanisms for heat generation within these materials were found to be highly dependent on the frequency range of excitation. Heat generation at lower frequencies corresponding to structural resonances is likely driven by bulk motion of the sample. Above these frequencies, wavelength-scale interactions of the particles and binder are proposed to be the main contributor to heating. The observed phenomenon may prove useful in the aid of current trace vapor detection methods for explosives.

  8. High-resolution Valence and Core Excitation Spectra via First-Principles Calculations and Experiment

    NASA Astrophysics Data System (ADS)

    Shirley, Eric; Fossard, F.; Gilmore, K.; Hug, G.; Kas, J. J.; Rehr, J. J.; Vila, F.

    We calculate the optical and C K-edge near edge spectra of crystalline and molecular C60 measured with high-resolution electron energy-loss spectroscopy. The calculations are carried out using at least three different methods: Bethe-Salpeter calculations using the NIST Bethe-Salpeter Equation solver (NBSE) in the valence and OCEAN (Obtaining Core Excitation with Ab initio methods and NBSE) suite [Gilmore et al., Comp. Phys. Comm., (2015)]; excited-core-hole calculations using XCH [D. Prendergast and G. Galli, Phys. Rev. Lett. 96, 215502 (2006)]; and constrained occupancy using StoBe (Stockholm-Berlin core-excitation code) [StoBe-deMon version 3.0, K. Hermann et al. (2009)]. They include self-energy effects, lifetime-damping, and Debye-Waller effects. A comparison of spectral features to those observed illustrates the sensitivity of certain features to computation details (e.g., self-energy corrections and core-hole screening). This may point to limitations of various approximations, e.g. in conventional BSE paradigm and/or the incomplete treatment of vibrational effects. Supported in part by DOE BES Grant DE-FG03-97ER45623 (JJR, JJK, FV).

  9. Relativistic calculations of excitation and ionization of highly charged ions by electron impact. Final technical report

    SciTech Connect

    Sampson, D.H.

    1992-04-15

    Our rapid relativistic atomic structure program and relativistic distorted-wave programs for excitation and ionization of highly charged ions were further improved. The generalized Briet interaction and other QED corrections were added to the atomic structure program, and the speed of the distorted-wave excitation program was increased by over an order of magnitude over what it was when our initial large-scale relativistic calculations of excitation of Ne-like ions were made. The improved programs were then used to calculate collision strengths for 330 transitions in F-like ions with 22 {le} Z {le} 92 and 248 transitions in Ni-like ions with 60 {le} Z {le} 92. We expanded the relativistic collision program to include an option to use atomic structure data by the well-known multi-configuration Dirac-Fock (MCDF) program of Grant and A coworkers. This was used in calculating collision strengths for the 45 {Delta}n = 0 transitions with n=2 in Be-like ions with 8 {le} Z {le} 92. This relativistic collision strength program was also extended to include an option to include the generalized Breis interaction in the scattering matrix elements and the importance of this for He-like, He-like and Li-like ions with Z = 26, 54 and 92 was studied. The factorization method was applied to ionization. Regardless of the complexity of the ion the ionization cross sections could be written as a sum of the products of a readily calculated coefficient that depends only on ion properties and a hydrogen-like cross section. Work was also done on excitation and ionization by directive and, in some cases spin-polarized electrons, which is of interest for some EBIT experiments and the study of solar flares. We also used our extensive collision strength results to test the

  10. Relativistic calculations of excitation and ionization of highly charged ions by electron impact

    SciTech Connect

    Sampson, D.H.

    1992-04-15

    Our rapid relativistic atomic structure program and relativistic distorted-wave programs for excitation and ionization of highly charged ions were further improved. The generalized Briet interaction and other QED corrections were added to the atomic structure program, and the speed of the distorted-wave excitation program was increased by over an order of magnitude over what it was when our initial large-scale relativistic calculations of excitation of Ne-like ions were made. The improved programs were then used to calculate collision strengths for 330 transitions in F-like ions with 22 [le] Z [le] 92 and 248 transitions in Ni-like ions with 60 [le] Z [le] 92. We expanded the relativistic collision program to include an option to use atomic structure data by the well-known multi-configuration Dirac-Fock (MCDF) program of Grant and A coworkers. This was used in calculating collision strengths for the 45 [Delta]n = 0 transitions with n=2 in Be-like ions with 8 [le] Z [le] 92. This relativistic collision strength program was also extended to include an option to include the generalized Breis interaction in the scattering matrix elements and the importance of this for He-like, He-like and Li-like ions with Z = 26, 54 and 92 was studied. The factorization method was applied to ionization. Regardless of the complexity of the ion the ionization cross sections could be written as a sum of the products of a readily calculated coefficient that depends only on ion properties and a hydrogen-like cross section. Work was also done on excitation and ionization by directive and, in some cases spin-polarized electrons, which is of interest for some EBIT experiments and the study of solar flares. We also used our extensive collision strength results to test the

  11. High-Rydberg Xenon Submillimeter-Wave Detector

    NASA Technical Reports Server (NTRS)

    Chutjian, Ara

    1987-01-01

    Proposed detector for infrared and submillimeter-wavelength radiation uses excited xenon atoms as Rydberg sensors instead of customary beams of sodium, potassium, or cesium. Chemically inert xenon easily stored in pressurized containers, whereas beams of dangerously reactive alkali metals must be generated in cumbersome, unreliable ovens. Xenon-based detector potential for infrared astronomy and for Earth-orbiter detection of terrestrial radiation sources. Xenon atoms excited to high energy states in two stages. Doubly excited atoms sensitive to photons in submillimeter wavelength range, further excited by these photons, then ionized and counted.

  12. HIGH-EXCITATION EMISSION LINES NEAR ETA CARINAE, AND ITS LIKELY COMPANION STAR

    SciTech Connect

    Mehner, Andrea; Davidson, Kris; Humphreys, Roberta M.; Ferland, Gary J. E-mail: kd@astro.umn.ed E-mail: gjferland@googlemail.co

    2010-02-10

    In order to study the distribution of gas and ionizing radiation around eta Car and their implications for its likely companion star, we have examined high-excitation emission lines of [Ne III], [Fe III], etc., in spectra obtained with the Hubble Space Telescope/Space Telescope Imaging Spectrograph instrument during 1998-2004. Our principal results, some of them unexpected, are as follows. (1) The high-excitation fluxes varied systematically and non-trivially throughout eta Car's 5.5 year spectroscopic cycle. Instead of rising to a plateau after the 1998 'event', they changed continuously with a maximum in mid-cycle. (2) At one significant location a brief, strong secondary maximum occurred just before the 2003.5 spectroscopic event. (3) These emission lines are strongly concentrated at the 'Weigelt knots' several hundred AU northwest of the star. With less certainty, [Ne III] appears to be somewhat more concentrated than [Fe III]. (4) A faster, blueshifted component of each feature appears concentrated near the star and elongated perpendicular to the system's bipolar axis. This structure may be related to the equatorial outflow and/or to dense material known to exist along our line of sight to the star. (5) Using the photoionization program Cloudy, we estimated the range of parameters for the hot secondary star that would give satisfactory high-excitation line ratios in the ejecta. T{sub eff} {approx} 39, 000 K and L {approx} 4 x 10{sup 5} L{sub sun}, for example, would be satisfactory. The allowed region in parameter space is wider (and mostly less luminous) than some previous authors suggested.

  13. Decays of doubly charmed meson molecules

    NASA Astrophysics Data System (ADS)

    Molina, R.; Nagahiro, H.; Hosaka, A.

    2016-01-01

    If the X(3872), Y(3940) and X(4160) are D*D ¯+c .c ., D*D ¯* and DS*D¯S* molecules, respectively, there should be doubly charmed mesons (D(*)D(*)). In this talk we predict two states with JP = 1+ in the charm = 2 sector, one DD* state around 3850 MeV, other D*D* state with mass around 3970 MeV, and other two similar states in the (charm = 2; strangeness = sector. Besides that, we evaluate the decay widths of doubly charm mesons D*D*(1+), into DDπ and DDγ. These decays are mediated by anomalous couplings D*D* - DD*, with the subsequent decay of D* into Dπ or Dγ.

  14. Entropy production of doubly stochastic quantum channels

    NASA Astrophysics Data System (ADS)

    Müller-Hermes, Alexander; Stilck França, Daniel; Wolf, Michael M.

    2016-02-01

    We study the entropy increase of quantum systems evolving under primitive, doubly stochastic Markovian noise and thus converging to the maximally mixed state. This entropy increase can be quantified by a logarithmic-Sobolev constant of the Liouvillian generating the noise. We prove a universal lower bound on this constant that stays invariant under taking tensor-powers. Our methods involve a new comparison method to relate logarithmic-Sobolev constants of different Liouvillians and a technique to compute logarithmic-Sobolev inequalities of Liouvillians with eigenvectors forming a projective representation of a finite abelian group. Our bounds improve upon similar results established before and as an application we prove an upper bound on continuous-time quantum capacities. In the last part of this work we study entropy production estimates of discrete-time doubly stochastic quantum channels by extending the framework of discrete-time logarithmic-Sobolev inequalities to the quantum case.

  15. Ablation of GaAs by Intense, Ultrafast Electronic Excitation from Highly Charged Ions

    SciTech Connect

    Schenkel, T.; Hamza, A.V.; Barnes, A.V.; Schneider, D.H.; Banks, J.C.; Doyle, B.L.

    1998-09-01

    We have measured total ablation rates and secondary ion yields from undoped GaAs(100) interacting with slow (v=6.6{times}10{sup 5} m /s) , very highly charged ions. Ablation rates increase strongly as a function of projectile charge. Some 1400thinspthinsptarget atoms are removed when a single Th{sup 70+} ion deposits a potential energy of 152.6thinspthinspkeV within a few femtoseconds into a nanometer-sized target volume. We discuss models for ablation of semiconductors by intense, ultrafast electronic excitation. {copyright} {ital 1998} {ital The American Physical Society}

  16. PG 1012-029 - A high-excitation eclipsing cataclysmic variable

    NASA Technical Reports Server (NTRS)

    Penning, W. R.; Ferguson, D. H.; Mcgraw, J. T.; Liebert, J.; Green, R. F.

    1984-01-01

    The paper presents a photometric and spectrophotometric analysis of a new eclipsing cataclysmic variable, PG 1012-029, with an orbital period of 3 hr 14 minutes 18.7 s. The eclipse depth reaches 1.9 mag, is rounded at minimum, and shows a prolonged egress 'shoulder', as found for UX UMa and some other eclipsing systems. The spectrum shows strong high-excitation lines at optical and UV wavelengths. A large fraction of the He II flux disappears during the eclipse, when the hydrogen spectrum fits a cooler temperature, and the continuum reddens. This behavior is attributed to eclipse of the hotter inner disk region.

  17. High Resolution UV Emission Spectroscopy of Molecules Excited by Electron Impact

    NASA Technical Reports Server (NTRS)

    James, G. K.; Ajello, J. M.; Beegle, L.; Ciocca, M.; Dziczek, D.; Kanik, I.; Noren, C.; Jonin, C.; Hansen, D.

    1999-01-01

    Photodissociation via discrete line absorption into predissociating Rydberg and valence states is the dominant destruction mechanism of CO and other molecules in the interstellar medium and molecular clouds. Accurate values for the rovibronic oscillator strengths of these transitions and predissociation yields of the excited states are required for input into the photochemical models that attempt to reproduce observed abundances. We report here on our latest experimental results of the electron collisional properties of CO and N2 obtained using the 3-meter high resolution single-scattering spectroscopic facility at JPL.

  18. Efficient high-resolution RF pulse design applied to simultaneous multi-slice excitation

    NASA Astrophysics Data System (ADS)

    Aigner, Christoph Stefan; Clason, Christian; Rund, Armin; Stollberger, Rudolf

    2016-02-01

    RF pulse design via optimal control is typically based on gradient and quasi-Newton approaches and therefore suffers from slow convergence. We present a flexible and highly efficient method that uses exact second-order information within a globally convergent trust-region CG-Newton method to yield an improved convergence rate. The approach is applied to the design of RF pulses for single- and simultaneous multi-slice (SMS) excitation and validated using phantom and in vivo experiments on a 3 T scanner using a modified gradient echo sequence.

  19. High electronic excitations and ion beam mixing effects in high energy ion irradiated Fe/Si multilayers

    SciTech Connect

    Bauer, P.; Dufour, C.; Jaouen, C.; Marchal, G.; Pacaud, J.; Grilhe, J.; Jousset, J.C.

    1997-01-01

    M{umlt o}ssbauer spectroscopy ({sup 57}Fe) shows evidence for mixing effects induced by electronic energy deposition in nanoscale Fe/Si multilayers irradiated with swift heavy ions. A decrease in the mixing efficiency with electronic stopping power is reported; a threshold is found, under which iron environment modifications no longer occur. The kinetics of Fe{endash}Si phase formation after irradiation suggests the existence of three regimes: (i) for high excitation levels, a magnetic amorphous phase is formed directly in the wake of the incoming ion and an almost complete mixing is reached at low fluence (10{sup 13} U/cm{sup 2}); (ii) for low excitation levels, a paramagnetic Si-rich amorphous phase is favored at the interface while crystalline iron subsists at high fluences; (iii) for intermediate excitation levels, saturation effects are observed and the formation rate of both magnetic and paramagnetic phases points to direct mixing in the ion wake but with a reduced track length in comparison to U irradiation. The measured interfacial mixing cross section induced by electronic energy deposition suggests that a thermal diffusion process is mainly involved in addition to damage creation. {copyright} {ital 1997 American Institute of Physics.}

  20. Filtering Characteristics of Doubly Sinusoidal Periodic Media

    NASA Astrophysics Data System (ADS)

    Dong, Tian-Lin; Chen, Ping

    2006-03-01

    Dispersion and filtering characteristics of doubly sinusoidal periodic (DSP) medium is investigated. Based on its feature different from singly sinusoidal periodic medium, a novel dual-band filter model is realized and measured. The results show that even a single unit cell of DSP medium can provide rather good filtering performance. And the filter is of perfect compatibility with regular waveguide and substrate integrated waveguide technology.

  1. Three-charge doubly rotating black ring

    SciTech Connect

    Gal'tsov, Dmitri V.; Scherbluk, Nikolai G.

    2010-02-15

    Using the recently proposed new solution generating technique, we construct the charged version of the Pomeranski-Senkov doubly rotating black ring in the U(1){sup 3} five-dimensional supergravity. For arbitrary values of charges the solution is unbalanced, but the Dirac-Misner string is removed when two of the charges are set to zero. In this particular case our solution can be uplifted to some solutions of six-dimensional vacuum gravity.

  2. Negative Oxygen Ion Formation in a Pulsed Inductively RF Excited Argon-Oxygen Discharge and the Influence of Highly Excited Oxygen Molecules

    NASA Astrophysics Data System (ADS)

    Katsch, H.-M.; Manthey, C.; Döbele, H.-F.

    2003-10-01

    The temporal behavior of negative oxygen ions oxygen / argon mixtures was investigated in the afterglow of a pulsed inductively excited modified GEC reactor. The objective of this investigation is an improved understanding of the production reactions of the negative ions and the loss processes of negative ions during the plasma decay phase. Collisions of O-minus ions with O atoms and metastable oxygen molecules lead to considerable electron production in the afterglow. This late supply of electrons entails a delayed formation of a so-called ion-ion plasma. Discharges with admixtures of argon (up to 8:2 argon : oxygen) are also strongly electronegative. An increase of the absolute O-minus density is observed with increasing argon fraction. At low pressures and high contents of argon it is necessary to consider an additional production reaction channel for the negative ions in order to explain the measured increase of the negative ion density. Appearance potential mass spectroscopy measurements show an increase of highly excited oxygen molecules with increasing argon fraction. It is, therefore, likely that additional negative ions are generated by dissociative attachment of highly excited metastable oxygen molecules [1]. [1] D. Hayashi and K. Kadota, J. Appl. Phys. 83 (1998) 697 This project is funded by the Bundesminister für Bildung und Forschung BMBF (FKZ 13N8052).

  3. 20 {mu}s isomeric state in doubly odd {sub 61}{sup 134}Pm

    SciTech Connect

    Cullen, D. M.; Mason, P. J. R; Rigby, S. V.; Kishada, A. M.; Varley, B. J.; Scholey, C.; Eeckhaudt, S.; Grahn, T.; Greenlees, P. T.; Jakobsson, U.; Jones, P. M.; Julin, R.; Juutinen, S.; Ketelhut, S.; Leino, M.; Leppaenen, A.-P.; Maentyniemi, K.; Nieminen, P.; Nyman, M.; Pakarinen, J.

    2009-08-15

    Recoil-isomer tagging at the Accelerator Laboratory of the University of Jyvaeskylae has been used to establish the isomeric nature of a known (7{sup -}) excited state in the doubly odd nucleus {sup 134}Pm. The isomeric state was determined to have a half-life of 20(1) {mu}s and was populated from the decay of a {pi}h{sub 11/2} x {nu}h{sub 11/2} band using the {sup 92}Mo({sup 54}Fe,2{alpha}3pn) reaction at 305 and 315 MeV. The isomer decays by a 71-keV transition that provides an intermediate step in linking the established {sup 134}Pm high-spin level scheme to the lower-spin states observed from the {beta} decay of {sup 134}Sm. Electron-conversion analysis for the 71-keV {gamma}-ray transition reveals that it is of E1 character and its small reduced-transition probability suggests that {sup 134}Pm may have a nuclear shape more rigid than that of the neighboring nuclei.

  4. Room temperature, very sensitive thermometer using a doubly clamped microelectromechanical beam resonator for bolometer applications

    NASA Astrophysics Data System (ADS)

    Zhang, Y.; Watanabe, Y.; Hosono, S.; Nagai, N.; Hirakawa, K.

    2016-04-01

    We propose a room temperature, all electrical driving and detecting, very sensitive thermometer structure using a microelectromechanical (MEMS) resonator for bolometer applications. We have fabricated a GaAs doubly clamped MEMS beam resonator whose oscillation can be excited and detected by the piezoelectric effect. When a heating power is applied to a NiCr film deposited on the MEMS beam surface, internal thermal stress is generated in the beam, leading to a reduction in the resonance frequency. The present device detects the shift in the resonance frequency caused by heating and works as a very sensitive thermometer. When the resonator was driven by a voltage slightly below the threshold for the nonlinear, hysteretic oscillation, the thermometer showed a voltage responsivity of about 3300 V/W, while keeping a low noise spectral density of about 60 nV/Hz1/2, demonstrating a noise equivalent power of <20 pW/Hz1/2 even at room temperature. The observed effect can be used for realizing high-sensitivity terahertz bolometers for room-temperature operation.

  5. High power visible light emitting diodes as pulsed excitation sources for biomedical photoacoustics

    PubMed Central

    Allen, Thomas J.; Beard, Paul C.

    2016-01-01

    The use of visible light emitting diodes (LEDs) as an alternative to Q-switched lasers conventionally used as photoacoustic excitation sources has been explored. In common with laser diodes, LEDs offer the advantages of compact size, low cost and high efficiency. However, laser diodes suitable for pulsed photoacoustic generation are typically available only at wavelengths greater than 750nm. By contrast, LEDs are readily available at visible wavelengths below 650nm where haemoglobin absorption is significantly higher, offering the prospect of increased SNR for superficial vascular imaging applications. To demonstrate feasibility, a range of low cost commercially available LEDs operating in the 420-620nm spectral range were used to generate photoacoustic signals in physiologically realistic vascular phantoms. Overdriving with 200ns pulses and operating at a low duty cycle enabled pulse energies up to 10µJ to be obtained with a 620nm LED. By operating at a high pulse repetition frequency (PRF) in order to rapidly signal average over many acquisitions, this pulse energy was sufficient to generate detectable signals in a blood filled tube immersed in an Intralipid suspension (µs’ = 1mm−1) at a depth of 15mm using widefield illumination. In addition, a compact four-wavelength LED (460nm, 530nm, 590nm, 620nm) in conjunction with a coded excitation scheme was used to illustrate rapid multiwavelength signal acquisition for spectroscopic applications. This study demonstrates that LEDs could find application as inexpensive and compact multiwavelength photoacoustic excitation sources for imaging superficial vascular anatomy. Published by The Optical Society under the terms of the Creative Commons Attribution 4.0 License. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. PMID:27446652

  6. High power visible light emitting diodes as pulsed excitation sources for biomedical photoacoustics.

    PubMed

    Allen, Thomas J; Beard, Paul C

    2016-04-01

    The use of visible light emitting diodes (LEDs) as an alternative to Q-switched lasers conventionally used as photoacoustic excitation sources has been explored. In common with laser diodes, LEDs offer the advantages of compact size, low cost and high efficiency. However, laser diodes suitable for pulsed photoacoustic generation are typically available only at wavelengths greater than 750nm. By contrast, LEDs are readily available at visible wavelengths below 650nm where haemoglobin absorption is significantly higher, offering the prospect of increased SNR for superficial vascular imaging applications. To demonstrate feasibility, a range of low cost commercially available LEDs operating in the 420-620nm spectral range were used to generate photoacoustic signals in physiologically realistic vascular phantoms. Overdriving with 200ns pulses and operating at a low duty cycle enabled pulse energies up to 10µJ to be obtained with a 620nm LED. By operating at a high pulse repetition frequency (PRF) in order to rapidly signal average over many acquisitions, this pulse energy was sufficient to generate detectable signals in a blood filled tube immersed in an Intralipid suspension (µs' = 1mm(-1)) at a depth of 15mm using widefield illumination. In addition, a compact four-wavelength LED (460nm, 530nm, 590nm, 620nm) in conjunction with a coded excitation scheme was used to illustrate rapid multiwavelength signal acquisition for spectroscopic applications. This study demonstrates that LEDs could find application as inexpensive and compact multiwavelength photoacoustic excitation sources for imaging superficial vascular anatomy. Published by The Optical Society under the terms of the Creative Commons Attribution 4.0 License. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI. PMID:27446652

  7. Effect of collective response on electron capture and excitation in collisions of highly charged ions with fullerenes.

    PubMed

    Kadhane, U; Misra, D; Singh, Y P; Tribedi, Lokesh C

    2003-03-01

    Projectile deexcitation Lyman x-ray emission following electron capture and K excitation has been studied in collisions of bare and Li-like sulphur ions (of energy 110 MeV) with fullerenes (C(60)/C(70)) and different gaseous targets. The intensity ratios of different Lyman x-ray lines in collisions with fullerenes are found to be substantially lower than those for the gas targets, both for capture and excitation. This has been explained in terms of a model based on "solidlike" effect, namely, wakefield induced stark mixing of the excited states populated via electron capture or K excitation: a collective phenomenon of plasmon excitation in the fullerenes under the influence of heavy, highly charged ions. PMID:12689221

  8. Observation of New Dynamics in the State-Resolved Collisional Relaxation of Highly Excited Molecules

    NASA Astrophysics Data System (ADS)

    Echebiri, Geraldine O.; Smarte, Matthew; Walters, Wendell W.; Cleveland, Jill M.; McCarl, Christine; Kunin, Alice; Mullin, Amy S.

    2013-06-01

    The dynamics of collisional deactivation of highly energized molecules, pyrazine-h_{4} and pyrazine-d_{4}, by HCl molecules at 300 K show evidence of a new mechanism for collisional energy transfer. Highly vibrationally excited (E_{vib} = 37,900 wn) pyrazine-h_{4} and pyrazine-d_{4} molecules are produced in separate experiments by pulsed excitation with the fourth harmonic output of a Nd:YAG laser at λ = 266 nm. Collisions between the energized isotopes and HCl molecules are monitored by measuring the nascent transient IR absorption of scattered HCl in individual rotational states. The results indicate that HCl molecules are scattered with a gain in rotational and translational energy, but the largest recoil energies are observed for the lowest rotational energy states of HCl. This behavior is opposite to that seen for other bath molecules including DCl and CO_{2}. The results point to differences in intermolecular interactions between the energy donor and acceptor molecules as contributing factors to the observed differences in the mechanism of energy transfer.

  9. High spectral specificity of local chemical components characterization with multichannel shift-excitation Raman spectroscopy

    PubMed Central

    Chen, Kun; Wu, Tao; Wei, Haoyun; Wu, Xuejian; Li, Yan

    2015-01-01

    Raman spectroscopy has emerged as a promising tool for its noninvasive and nondestructive characterization of local chemical structures. However, spectrally overlapping components prevent the specific identification of hyperfine molecular information of different substances, because of limitations in the spectral resolving power. The challenge is to find a way of preserving scattered photons and retrieving hidden/buried Raman signatures to take full advantage of its chemical specificity. Here, we demonstrate a multichannel acquisition framework based on shift-excitation and slit-modulation, followed by mathematical post-processing, which enables a significant improvement in the spectral specificity of Raman characterization. The present technique, termed shift-excitation blind super-resolution Raman spectroscopy (SEBSR), uses multiple degraded spectra to beat the dispersion-loss trade-off and facilitate high-resolution applications. It overcomes a fundamental problem that has previously plagued high-resolution Raman spectroscopy: fine spectral resolution requires large dispersion, which is accompanied by extreme optical loss. Applicability is demonstrated by the perfect recovery of fine structure of the C-Cl bending mode as well as the clear discrimination of different polymorphs of mannitol. Due to its enhanced discrimination capability, this method offers a feasible route at encouraging a broader range of applications in analytical chemistry, materials and biomedicine. PMID:26350355

  10. Trajectory study of supercollision relaxation in highly vibrationally excited pyrazine and CO2.

    PubMed

    Li, Ziman; Sansom, Rebecca; Bonella, Sara; Coker, David F; Mullin, Amy S

    2005-09-01

    Classical trajectory calculations were performed to simulate state-resolved energy transfer experiments of highly vibrationally excited pyrazine (E(vib) = 37,900 cm(-1)) and CO(2), which were conducted using a high-resolution transient infrared absorption spectrometer. The goal here is to use classical trajectories to simulate the supercollision energy transfer pathway wherein large amounts of energy are transferred in single collisions in order to compare with experimental results. In the trajectory calculations, Newton's laws of motion are used for the molecular motion, isolated molecules are treated as collections of harmonic oscillators, and intermolecular potentials are formed by pairwise Lennard-Jones potentials. The calculations qualitatively reproduce the observed energy partitioning in the scattered CO(2) molecules and show that the relative partitioning between bath rotation and translation is dependent on the moment of inertia of the bath molecule. The simulations show that the low-frequency modes of the vibrationally excited pyrazine contribute most to the strong collisions. The majority of collisions lead to small DeltaE values and primarily involve single encounters between the energy donor and acceptor. The large DeltaE exchanges result from both single impulsive encounters and chattering collisions that involve multiple encounters. PMID:16834139

  11. ACCRETION PROPERTIES OF HIGH- AND LOW-EXCITATION YOUNG RADIO GALAXIES

    SciTech Connect

    Son, Donghoon; Woo, Jong-Hak; Park, Daeseong; Kim, Sang Chul; Fu, Hai; Kawakatu, Nozomu; Bennert, Vardha N.; Nagao, Tohru

    2012-10-01

    Young radio galaxies (YRGs) provide an ideal laboratory to explore the connection between the accretion disk and radio jet thanks to their recent jet formation. We investigate the relationship between the emission-line properties, the black hole accretion rate, and the radio properties using a sample of 34 low-redshift (z < 0.4) YRGs. We classify YRGs as high-excitation galaxies (HEGs) and low-excitation galaxies (LEGs) based on the flux ratio of high-ionization to low-ionization emission lines. Using the H{alpha} luminosities as a proxy of accretion rate, we find that HEGs in YRGs have {approx}1 dex higher Eddington ratios than LEGs in YRGs, suggesting that HEGs have a higher mass accretion rate or higher radiative efficiency than LEGs. In agreement with previous studies, we find that the luminosities of emission lines, in particular H{alpha}, are correlated with radio core luminosity, suggesting that accretion and young radio activities are fundamentally connected.

  12. A model for energy transfer in collisions of atoms with highly excited molecules.

    PubMed

    Houston, Paul L; Conte, Riccardo; Bowman, Joel M

    2015-05-21

    A model for energy transfer in the collision between an atom and a highly excited target molecule has been developed on the basis of classical mechanics and turning point analysis. The predictions of the model have been tested against the results of trajectory calculations for collisions of five different target molecules with argon or helium under a variety of temperatures, collision energies, and initial rotational levels. The model predicts selected moments of the joint probability distribution, P(Jf,ΔE) with an R(2) ≈ 0.90. The calculation is efficient, in most cases taking less than one CPU-hour. The model provides several insights into the energy transfer process. The joint probability distribution is strongly dependent on rotational energy transfer and conservation laws and less dependent on vibrational energy transfer. There are two mechanisms for rotational excitation, one due to motion normal to the intermolecular potential and one due to motion tangential to it and perpendicular to the line of centers. Energy transfer is found to depend strongly on the intermolecular potential and only weakly on the intramolecular potential. Highly efficient collisions are a natural consequence of the energy transfer and arise due to collisions at "sweet spots" in the space of impact parameter and molecular orientation. PMID:25907301

  13. Acoustic radiation force impulse (ARFI) imaging of zebrafish embryo by high-frequency coded excitation sequence.

    PubMed

    Park, Jinhyoung; Lee, Jungwoo; Lau, Sien Ting; Lee, Changyang; Huang, Ying; Lien, Ching-Ling; Kirk Shung, K

    2012-04-01

    Acoustic radiation force impulse (ARFI) imaging has been developed as a non-invasive method for quantitative illustration of tissue stiffness or displacement. Conventional ARFI imaging (2-10 MHz) has been implemented in commercial scanners for illustrating elastic properties of several organs. The image resolution, however, is too coarse to study mechanical properties of micro-sized objects such as cells. This article thus presents a high-frequency coded excitation ARFI technique, with the ultimate goal of displaying elastic characteristics of cellular structures. Tissue mimicking phantoms and zebrafish embryos are imaged with a 100-MHz lithium niobate (LiNbO₃) transducer, by cross-correlating tracked RF echoes with the reference. The phantom results show that the contrast of ARFI image (14 dB) with coded excitation is better than that of the conventional ARFI image (9 dB). The depths of penetration are 2.6 and 2.2 mm, respectively. The stiffness data of the zebrafish demonstrate that the envelope is harder than the embryo region. The temporal displacement change at the embryo and the chorion is as large as 36 and 3.6 μm. Consequently, this high-frequency ARFI approach may serve as a remote palpation imaging tool that reveals viscoelastic properties of small biological samples. PMID:22101757

  14. A system for optical high resolution screening of electrical excitable cells.

    PubMed

    Müller, Oliver; Tian, Qinghai; Zantl, Roman; Kahl, Valentin; Lipp, Peter; Kaestner, Lars

    2010-03-01

    The application of primary excitable cells for high content screening (HCS) requires a multitude of novel developments including cell culture and multi-well plates. Here we introduce a novel system combining optimised culture conditions of primary adult cardiomyocytes with the particular needs of excitable cells for arbitrary field stimulation of individual wells. The major advancements of our design were tested in calcium imaging experiments and comprise (i) each well of the plate can be subjected to individual pulse protocols, (ii) the software driving electrical stimulation can run as a stand-alone application but also as a plug-in in HCS software packages, (iii) the optical properties of the plastic substrate (foil) resemble those of glass coverslips fostering high resolution immersion-based microscopy, (iv) the bottom of the foil is coated with an oleophobic layer that prevents immersion oil from sticking, (v) the top of the foil is coated with an elastic film. The latter enables cardiomyocytes to display loaded contractions by mimicking the physiologically occurring local elastic network (e.g. extracellular matrix) and results in significantly increased contractions (with identical calcium transients) when compared to non-elastic substrates. Thus, our novel design and culture conditions represent an essential further step towards the application of primary cultured adult cardiomyocytes for HCS applications. PMID:20036001

  15. High spectral specificity of local chemical components characterization with multichannel shift-excitation Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Chen, Kun; Wu, Tao; Wei, Haoyun; Wu, Xuejian; Li, Yan

    2015-09-01

    Raman spectroscopy has emerged as a promising tool for its noninvasive and nondestructive characterization of local chemical structures. However, spectrally overlapping components prevent the specific identification of hyperfine molecular information of different substances, because of limitations in the spectral resolving power. The challenge is to find a way of preserving scattered photons and retrieving hidden/buried Raman signatures to take full advantage of its chemical specificity. Here, we demonstrate a multichannel acquisition framework based on shift-excitation and slit-modulation, followed by mathematical post-processing, which enables a significant improvement in the spectral specificity of Raman characterization. The present technique, termed shift-excitation blind super-resolution Raman spectroscopy (SEBSR), uses multiple degraded spectra to beat the dispersion-loss trade-off and facilitate high-resolution applications. It overcomes a fundamental problem that has previously plagued high-resolution Raman spectroscopy: fine spectral resolution requires large dispersion, which is accompanied by extreme optical loss. Applicability is demonstrated by the perfect recovery of fine structure of the C-Cl bending mode as well as the clear discrimination of different polymorphs of mannitol. Due to its enhanced discrimination capability, this method offers a feasible route at encouraging a broader range of applications in analytical chemistry, materials and biomedicine.

  16. Two-component Structure in the Entanglement Spectrum of Highly Excited States

    NASA Astrophysics Data System (ADS)

    Yang, Zhi-Cheng; Chamon, Claudio; Hamma, Alioscia; Mucciolo, Eduardo

    We study the entanglement spectrum of highly excited eigenstates of two known models which exhibit a many-body localization transition, namely the one-dimensional random-field Heisenberg model and the quantum random energy model. Our results indicate that the entanglement spectrum shows a ``two-component'' structure: a universal part that is associated to Random Matrix Theory, and a non-universal part that is model dependent. The non-universal part manifests the deviation of the highly excited eigenstate from a true random state even in the thermalized phase where the Eigenstate Thermalization Hypothesis holds. The fraction of the spectrum containing the universal part decreases continuously as one approaches the critical point and vanishes in the localized phase in the thermodynamic limit. We use the universal part fraction to construct a new order parameter for the many-body delocalized-to-localized transition. Two toy models based on Rokhsar-Kivelson type wavefunctions are constructed and their entanglement spectra are shown to exhibit the same structure.

  17. Predicting the effect of angular momentum on the dissociation dynamics of highly rotationally excited radical intermediates

    SciTech Connect

    Brynteson, Matthew D.; Butler, Laurie J.

    2015-02-07

    We present a model which accurately predicts the net speed distributions of products resulting from the unimolecular decomposition of rotationally excited radicals. The radicals are produced photolytically from a halogenated precursor under collision-free conditions so they are not in a thermal distribution of rotational states. The accuracy relies on the radical dissociating with negligible energetic barrier beyond the endoergicity. We test the model predictions using previous velocity map imaging and crossed laser-molecular beam scattering experiments that photolytically generated rotationally excited CD{sub 2}CD{sub 2}OH and C{sub 3}H{sub 6}OH radicals from brominated precursors; some of those radicals then undergo further dissociation to CD{sub 2}CD{sub 2} + OH and C{sub 3}H{sub 6} + OH, respectively. We model the rotational trajectories of these radicals, with high vibrational and rotational energy, first near their equilibrium geometry, and then by projecting each point during the rotation to the transition state (continuing the rotational dynamics at that geometry). This allows us to accurately predict the recoil velocity imparted in the subsequent dissociation of the radical by calculating the tangential velocities of the CD{sub 2}CD{sub 2}/C{sub 3}H{sub 6} and OH fragments at the transition state. The model also gives a prediction for the distribution of angles between the dissociation fragments’ velocity vectors and the initial radical’s velocity vector. These results are used to generate fits to the previously measured time-of-flight distributions of the dissociation fragments; the fits are excellent. The results demonstrate the importance of considering the precession of the angular velocity vector for a rotating radical. We also show that if the initial angular momentum of the rotating radical lies nearly parallel to a principal axis, the very narrow range of tangential velocities predicted by this model must be convoluted with a J = 0 recoil

  18. Scaling of collision strengths for highly-excited states of ions of the H- and He-like sequences

    NASA Astrophysics Data System (ADS)

    Fernández-Menchero, L.; Del Zanna, G.; Badnell, N. R.

    2016-08-01

    Emission lines from highly-excited states (n ≥ 5) of H- and He-like ions have been detected in astrophysical sources and fusion plasmas. For such excited states, R-matrix or distorted wave calculations for electron-impact excitation are very limited, due to the large size of the atomic basis set needed to describe them. Calculations for n ≥ 6 are also not generally available. We study the behaviour of the electron-impact excitation collision strengths and effective collision strengths for the most important transitions used to model electron collision dominated astrophysical plasmas, solar, for example. We investigate the dependence on the relevant parameters: the principal quantum number n or the nuclear charge Z. We also estimate the importance of coupling to highly-excited states and the continuum by comparing the results of different sized calculations. We provide analytic formulae to calculate the electron-impact excitation collision strengths and effective collision strengths to highly-excited states (n ≥ 8) of H- and He-like ions. These extrapolated effective collision strengths can be used to interpret astrophysical and fusion plasma via collisional-radiative modelling. Tables of atomic data for Si xiii and S xv are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/592/A135

  19. Pressure-induced emergence of unusually high-frequency transverse excitations in a liquid alkali metal: Evidence of two types of collective excitations contributing to the transverse dynamics at high pressures

    NASA Astrophysics Data System (ADS)

    Bryk, Taras; Ruocco, G.; Scopigno, T.; Seitsonen, Ari P.

    2015-09-01

    Unlike phonons in crystals, the collective excitations in liquids cannot be treated as propagation of harmonic displacements of atoms around stable local energy minima. The viscoelasticity of liquids, reflected in transition from the adiabatic to elastic high-frequency speed of sound and in absence of the long-wavelength transverse excitations, results in dispersions of longitudinal (L) and transverse (T) collective excitations essentially different from the typical phonon ones. Practically, nothing is known about the effect of high pressure on the dispersion of collective excitations in liquids, which causes strong changes in liquid structure. Here dispersions of L and T collective excitations in liquid Li in the range of pressures up to 186 GPa were studied by ab initio simulations. Two methodologies for dispersion calculations were used: direct estimation from the peak positions of the L/T current spectral functions and simulation-based calculations of wavenumber-dependent collective eigenmodes. It is found that at ambient pressure, the longitudinal and transverse dynamics are well separated, while at high pressures, the transverse current spectral functions, density of vibrational states, and dispersions of collective excitations yield evidence of two types of propagating modes that contribute strongly to transverse dynamics. Emergence of the unusually high-frequency transverse modes gives evidence of the breakdown of a regular viscoelastic theory of transverse dynamics, which is based on coupling of a single transverse propagating mode with shear relaxation. The explanation of the observed high-frequency shift above the viscoelastic value is given by the presence of another branch of collective excitations. With the pressure increasing, coupling between the two types of collective excitations is rationalized within a proposed extended viscoelastic model of transverse dynamics.

  20. Pressure-induced emergence of unusually high-frequency transverse excitations in a liquid alkali metal: Evidence of two types of collective excitations contributing to the transverse dynamics at high pressures

    SciTech Connect

    Bryk, Taras; Ruocco, G.; Scopigno, T.

    2015-09-14

    Unlike phonons in crystals, the collective excitations in liquids cannot be treated as propagation of harmonic displacements of atoms around stable local energy minima. The viscoelasticity of liquids, reflected in transition from the adiabatic to elastic high-frequency speed of sound and in absence of the long-wavelength transverse excitations, results in dispersions of longitudinal (L) and transverse (T) collective excitations essentially different from the typical phonon ones. Practically, nothing is known about the effect of high pressure on the dispersion of collective excitations in liquids, which causes strong changes in liquid structure. Here dispersions of L and T collective excitations in liquid Li in the range of pressures up to 186 GPa were studied by ab initio simulations. Two methodologies for dispersion calculations were used: direct estimation from the peak positions of the L/T current spectral functions and simulation-based calculations of wavenumber-dependent collective eigenmodes. It is found that at ambient pressure, the longitudinal and transverse dynamics are well separated, while at high pressures, the transverse current spectral functions, density of vibrational states, and dispersions of collective excitations yield evidence of two types of propagating modes that contribute strongly to transverse dynamics. Emergence of the unusually high-frequency transverse modes gives evidence of the breakdown of a regular viscoelastic theory of transverse dynamics, which is based on coupling of a single transverse propagating mode with shear relaxation. The explanation of the observed high-frequency shift above the viscoelastic value is given by the presence of another branch of collective excitations. With the pressure increasing, coupling between the two types of collective excitations is rationalized within a proposed extended viscoelastic model of transverse dynamics.

  1. All-optical control of cardiac excitation: combined high-resolution optogenetic actuation and optical mapping.

    PubMed

    Entcheva, Emilia; Bub, Gil

    2016-05-01

    Cardiac tissue is an excitable system that can support complex spatiotemporal dynamics, including instabilities (arrhythmias) with lethal consequences. While over the last two decades optical mapping of excitation (voltage and calcium dynamics) has facilitated the detailed characterization of such arrhythmia events, until recently, no precise tools existed to actively interrogate cardiac dynamics in space and time. In this work, we discuss the combined use of new methods for space- and time-resolved optogenetic actuation and simultaneous fast, high resolution optical imaging of cardiac excitation waves. First, the mechanisms, limitations and unique features of optically induced responses in cardiomyocytes are outlined. These include the ability to bidirectionally control the membrane potential using depolarizing and hyperpolarizing opsins; the ability to induce prolonged sustained voltage changes; and the ability to control refractoriness and the shape of the cardiac action potential. At the syncytial tissue level, we discuss optogenetically enabled experimentation on cell-cell coupling, alteration of conduction properties and termination of propagating waves by light. Specific attention is given to space- and time-resolved application of optical stimulation using dynamic light patterns to perturb ongoing activation and to probe electrophysiological properties at desired tissue locations. The combined use of optical methods to perturb and to observe the system can offer new tools for precise feedback control of cardiac electrical activity, not available previously with pharmacological and electrical stimulation. These new experimental tools for all-optical electrophysiology allow for a level of precise manipulation and quantification of cardiac dynamics comparable in robustness to the computational setting, and can provide new insights into pacemaking, arrhythmogenesis and suppression or cardioversion. PMID:26857427

  2. Polarization spectroscopy of x-ray transitions from beam-excited highly charged ions

    SciTech Connect

    Beiersdorfer, P.; Lopez-Urrutia, J.C.; Decaux, V.; Widmann, K.; Neill, P.

    1997-01-01

    Polarization spectroscopy of x-ray lines represents a diagnostic tool to ascertain the presence of electron beams in high-temperature plasmas. Making use of the Livermore electron beam ion trap, which optimizes the linear x-ray line polarization by exciting highly charged ions with a monoenergetic electron beam, we have begun to develop polarization diagnostics and test theoretical models. Our measurement relies on the sensitivity of crystal spectrometers to the linear polarization of x-ray lines which depends on the value of the Bragg angle. We employed two spectrometers with differing analyzing crystals and simultaneously recorded the K-shell emission from heliumlike Fe{sup 24+} and lithiumlike Fe{sup 23+} ions at two different Bragg angles. A clear difference in the relative intensities of the dominant transitions is observed, which is attributed to the amount of linear polarization of the individual lines. {copyright} {ital 1997 American Institute of Physics.}

  3. Excited baryon form-factors at high momentum transfer at CEBAF at higher energies

    SciTech Connect

    Stoler, P.

    1994-04-01

    The possibilities of measuring the properties of excited nucleons at high Q{sup 2} by means of exclusive single meson production at CEBAF with an electron energy of 8 GeV is considered. The motivation is to access short range phenomena in baryon structure, and to investigate the transition from the low Q{sup 2} non-perturbative QCD regime, where constituent quark models are valid, to higher Q{sup 2} where it is believed perturbative QCD plays an increasingly important role. It is found that high quality baryon decay angular distributions can be obtained for the most prominent states up to Q{sup 2} {approximately} 12 GeV{sup 2}/c{sup 2} using a set of moderate resolution, large solid angle magnetic spectrometers.

  4. High energy excitations measured by neutron spectroscopy in FePS3

    NASA Astrophysics Data System (ADS)

    Rule, K C; Wildes, A R; Bewley, R I; Visser, D; Hicks, T J

    2009-03-01

    The quasi-two-dimensional antiferromagnet FePS3 has been investigated using inelastic neutron spectroscopy with the time-of-flight spectrometer HET at the ISIS spallation neutron source. In the paramagnetic regime, two clearly resolved, high energy excitations were observed in the low scattering angle detector banks at 195(5) meV and 430(10) meV. The absence of these transitions from the high angle detector banks indicates that they are likely to be due to the crystal fields and magnetic in origin. The two transitions most probably represent electronic transitions in the Fe2+ ion among the low lying crystal field and spin-orbit split levels raised from the ground state. It has not yet been determined why the energies are greater than those observed in a comparable Raman experiment.

  5. High energy excitations measured by neutron spectroscopy in FePS(3).

    PubMed

    Rule, K C; Wildes, A R; Bewley, R I; Visser, D; Hicks, T J

    2009-03-25

    The quasi-two-dimensional antiferromagnet FePS(3) has been investigated using inelastic neutron spectroscopy with the time-of-flight spectrometer HET at the ISIS spallation neutron source. In the paramagnetic regime, two clearly resolved, high energy excitations were observed in the low scattering angle detector banks at 195(5) meV and 430(10) meV. The absence of these transitions from the high angle detector banks indicates that they are likely to be due to the crystal fields and magnetic in origin. The two transitions most probably represent electronic transitions in the Fe(2+) ion among the low lying crystal field and spin-orbit split levels raised from the ground state. It has not yet been determined why the energies are greater than those observed in a comparable Raman experiment. PMID:21817456

  6. V. S. Lebedev and I. L. Beigman, Physics of Highly Excited Atoms and Ions

    NASA Astrophysics Data System (ADS)

    Mewe, R.

    1999-07-01

    This book contains a comprehensive description of the basic principles of the theoretical spectroscopy and experimental spectroscopic diagnostics of Rydberg atoms and ions, i.e., atoms in highly excited states with a very large principal quantum number (n≫1). Rydberg atoms are characterized by a number of peculiar physical properties as compared to atoms in the ground or a low excited state. They have a very small ionization potential (∝1/n2), the highly excited electron has a small orbital velocity (∝1/n), the radius (∝n2) is very large, the excited electron has a long orbital period (∝n3), and the radiation lifetime is very long (∝n3-5). At the same time the R. atom is very sensitive to perturbations from external fields in collisions with charged and neutral targets. In recent years, R. atoms have been observed in laboratory and cosmic conditions for n up to ˜1000, which means that the size amounts to about 0.1 mm, ˜106 times that of an atom in the ground state. The scope of this monograph is to familiarize the reader with today's approaches and methods for describing isolated R. atoms and ions, radiative transitions between highly excited states, and photoionization and photorecombination processes. The authors present a number of efficient methods for describing the structure and properties of R. atoms and calculating processes of collisions with neutral and charged particles as well as spectral-line broadening and shift of Rydberg atomic series in gases, cool and hot plasmas in laboratories and in astrophysical sources. Particular attention is paid to a comparison of theoretical results with available experimental data. The book contains 9 chapters. Chapter 1 gives an introduction to the basic properties of R. atoms (ions), Chapter 2 is devoted to an account of general methods describing an isolated Rydberg atom. Chapter 3 is focussed on the recent achievements in calculations of form factors and dipole matrix elements of different types of

  7. Performance optimization for doubly-fed generation systems

    NASA Astrophysics Data System (ADS)

    Bhowmik, Shibashis

    A variable speed generation (VSG) system converts energy from a variable resource such as wind or water flow into variable rotational mechanical energy of a turbine or a similar device that converts translational kinetic energy into rotational mechanical energy. The mechanical energy is then converted into electrical energy by an electrical generator. Presently available and proposed generators include systems based mainly on dc machines, synchronous and induction machine technology as well as reluctance machines. While extracting more energy from the resource, most proposed VSG systems suffer a cost disadvantage due to the required rating of the power electronic interface. This cost penalty may eventually render the additional energy capture meaningless. Thus, reducing the cost of the power electronic hardware is essential for VSG systems to achieve viable and competitive $/kWh ratios when compared to fossil fuel-based generating systems. A variable speed constant frequency (VSCF) system and controller are proposed that utilize a doubly-fed machine (DFM) as the energy conversion device. The system includes a power converter that provides the current excitation for the control winding of the DFM. Both the magnitude and frequency of the excitation is determined by an adaptive model-based controller which maximizes the power flow from the mechanical turbine to the electrical grid and reduces the generator losses by maintaining the maximum efficiency point throughout the mechanical input power range. The proposed strategy has been experimentally verified in controlled laboratory conditions for a proof-of-concept brushless doubly-fed machine (BDFM) system of 1500 Watts power rating. Issues relating to power converter development and its incorporation in the system have been investigated. The controller and circuit design of a four quadrant, AC/AC power converter is presented and a novel sensorless current controller for the active rectifier stage is presented in detail

  8. Progress in Neutron Scattering Studies of Spin Excitations in High-T(c) Cuprates

    SciTech Connect

    Fujita M.; Tranquada J.; Hiraka, H.; Matsuda, M.; Matsuura, M.; Wakimoto, S.; Xu, G.; Yamada, K.

    2012-01-01

    Neutron scattering experiments continue to improve our knowledge of spin fluctuations in layered cuprates, excitations that are symptomatic of the electronic correlations underlying high-temperature superconductivity. Time-of-flight spectrometers, together with new and varied single crystal samples, have provided a more complete characterization of the magnetic energy spectrum and its variation with carrier concentration. While the spin excitations appear anomalous in comparison with simple model systems, there is clear consistency among a variety of cuprate families. Focusing initially on hole-doped systems, we review the nature of the magnetic spectrum, and variations in magnetic spectral weight with doping. We consider connections with the phenomena of charge and spin stripe order, and the potential generality of such correlations as suggested by studies of magnetic-field and impurity induced order. We contrast the behavior of the hole-doped systems with the trends found in the electron-doped superconductors. Returning to hole-doped cuprates, studies of translation-symmetry-preserving magnetic order are discussed, along with efforts to explore new systems. We conclude with a discussion of future challenges.

  9. Carrier diffusion and recombination in highly excited InGaN/GaN heterostructures

    NASA Astrophysics Data System (ADS)

    Jarainas, K.; Aleksiejnas, R.; Malinauskas, T.; Sdius, M.; Miasojedovas, S.; Jurnas, S.; Ukauskas, A.; Gaska, R.; Zhang, J.; Shur, M. S.; Yang, J. W.; Kuoktis, E.; Khan, M. A.

    2005-04-01

    Time-resolved four-wave mixing and photoluminescence techniques have been combined for studies of MOCVD-grown InxGa1-xN/GaN/sapphire heterostructures with different indium content (0.08 < x < 0.15). In-plane diffusion and recombination of spatially-modulated carriers, confined in the front layer of 50-nm-thick InGaN, were monitored by a probe beam diffraction and provided an average value of a bipolar diffusion coefficient D 1-1.5 cm2/s and its dependence on the In content. A complete saturation of four-wave mixing (FWM) efficiency vs excitation energy was found prominent in a layer with 10% of In. The latter effect of saturation correlated well with the dependence of quantum efficiency of stimulated emission on In content in heterostructures. Short decay times of stimulated emission (10 ps) measured by time-resolved PL in highly excited structure allowed us to attribute the FWM saturation effect to the threshold of stimulated recombination.

  10. Time-resolved doubly bent crystal x-ray spectrometer

    SciTech Connect

    Hockaday, M.P.; Wilke, M.D.; Blake, R.L.; Vaninetti, J.; Gray, N.T.; Nedrow, P.T.

    1988-08-01

    X-ray spectroscopy is an essential tool in high-temperature plasma research. We describe a time-resolved x-ray spectrometer suitable for measuring spectra in harsh environments common to many very high-energy density laboratory plasma sources. The spectrometer consisted of a doubly curved Si(111) crystal diffraction element, a WL-1201 (ZnO:Ga) phosphor, a coherent fiber-optic array, and two visible streak cameras. The spectrometer design described here has a minimum time resolution of 1.3 ns with 2.8-eV spectral resolution over a 200-eV-wide bandpass in the 6--7-keV region of the spectrum. Complete system spectral throughput calibrations were done at the Cornell High Energy Synchrotron (CHESS). Details of the design and calibration results are presented.