Range-separated density-functional theory for molecular excitation energies
International Nuclear Information System (INIS)
Rebolini, E.
2014-01-01
Linear-response time-dependent density-functional theory (TDDFT) is nowadays a method of choice to compute molecular excitation energies. However, within the usual adiabatic semi-local approximations, it is not able to describe properly Rydberg, charge-transfer or multiple excitations. Range separation of the electronic interaction allows one to mix rigorously density-functional methods at short range and wave function or Green's function methods at long range. When applied to the exchange functional, it already corrects most of these deficiencies but multiple excitations remain absent as they need a frequency-dependent kernel. In this thesis, the effects of range separation are first assessed on the excitation energies of a partially-interacting system in an analytic and numerical study in order to provide guidelines for future developments of range-separated methods for excitation energy calculations. It is then applied on the exchange and correlation TDDFT kernels in a single-determinant approximation in which the long-range part of the correlation kernel vanishes. A long-range frequency-dependent second-order correlation kernel is then derived from the Bethe-Salpeter equation and added perturbatively to the range-separated TDDFT kernel in order to take into account the effects of double excitations. (author)
Rebolini, Elisa; Teale, Andrew M.; Helgaker, Trygve; Savin, Andreas; Toulouse, Julien
2018-06-01
A Görling-Levy (GL)-based perturbation theory along the range-separated adiabatic connection is assessed for the calculation of electronic excitation energies. In comparison with the Rayleigh-Schrödinger (RS)-based perturbation theory this GL-based perturbation theory keeps the ground-state density constant at each order and thus gives the correct ionisation energy at each order. Excitation energies up to first order in the perturbation have been calculated numerically for the helium and beryllium atoms and the hydrogen molecule without introducing any density-functional approximations. In comparison with the RS-based perturbation theory, the present GL-based perturbation theory gives much more accurate excitation energies for Rydberg states but similar excitation energies for valence states.
International Nuclear Information System (INIS)
Singh, Devendra P.; Unnati; Sharma, Manoj Kumar; Singh, Pushpendra P.; Singh, B.P.; Prasad, R.; Gupta, Sunita; Rakesh Kumar; Bhardwaj, H.D.
2006-01-01
In the present work, excitation functions for seven evaporation residues (ERs) produced via complete fusion and incomplete fusion processes in 16 O + 103 Rh system have been measured in the energy range ≅ 47-85 MeV, using recoil catcher technique followed by off-line gamma-ray spectrometry. Comparison of the experimental data with statistical model based computer code PACE 2 revealed dominance of incomplete fusion in reactions involving alpha-emission channels. To the best of our knowledge these reactions are being reported for the first time
International Nuclear Information System (INIS)
Li Wenfei; Zhang Fengshou; Chen Liewen
2001-01-01
Within the framework of Hartree-Fock theory using the extended Skyrme effective interaction, the isospin excitation energy as a function of relative neutron excess δ was investigated at different temperatures and densities. It was found that the isospin excitation energy decreased with the increment of temperature and/or the decrement of density. The authors pointed out that the decrement of isospin excitation energy was resulted from the weakening of quantum effect with increment of temperature and/or decrement of density. Meanwhile, the relationship between the isospin excitation energy and the symmetry energy was discussed and found that the symmetry energy was just a part of the isospin excitation energy. With increasing temperature and decreasing density, the contribution of the symmetry energy to the isospin excitation energy becomes more and more important. The isospin excitation energy as a function of relative neutron excess was also investigated using different potential parameters. The results shows that the isospin excitation energy is almost independent of the incompressibility and the effective mass, but strongly depends on the symmetry energy strength coefficient, which indicates that it is possible to extract the symmetry energy of the nuclear equation of state by investigating the isospin excitation energy in experiments
High energy nuclear excitations
International Nuclear Information System (INIS)
Gogny, D.; Decharge, J.
1983-09-01
The main purpose of this talk is to see whether a simple description of the nuclear excitations permits one to characterize some of the high energy structures recently observed. The discussion is based on the linear response to different external fields calculated using the Random Phase Approximation. For those structure in heavy ion collisions at excitation energies above 50 MeV which cannot be explained with such a simple approach, we discuss a possible mechanism for this heavy ion scattering
Hardness and excitation energy
Indian Academy of Sciences (India)
It is shown that the first excitation energy can be given by the Kohn-Sham hardness (i.e. the energy difference of the ground-state lowest unoccupied and highest occupied levels) plus an extra term coming from the partial derivative of the ensemble exchange-correlation energy with respect to the weighting factor in the ...
Mean excitation energies for molecular ions
Energy Technology Data Exchange (ETDEWEB)
Jensen, Phillip W.K.; Sauer, Stephan P.A. [Department of Chemistry, University of Copenhagen, Copenhagen (Denmark); Oddershede, Jens [Department of Physics, Chemistry, and Pharmacy, University of Southern Denmark, Odense (Denmark); Quantum Theory Project, Departments of Physics and Chemistry, University of Florida, Gainesville, FL (United States); Sabin, John R., E-mail: sabin@qtp.ufl.edu [Department of Physics, Chemistry, and Pharmacy, University of Southern Denmark, Odense (Denmark); Quantum Theory Project, Departments of Physics and Chemistry, University of Florida, Gainesville, FL (United States)
2017-03-01
The essential material constant that determines the bulk of the stopping power of high energy projectiles, the mean excitation energy, is calculated for a range of smaller molecular ions using the RPA method. It is demonstrated that the mean excitation energy of both molecules and atoms increase with ionic charge. However, while the mean excitation energies of atoms also increase with atomic number, the opposite is the case for mean excitation energies for molecules and molecular ions. The origin of these effects is explained by considering the spectral representation of the excited state contributing to the mean excitation energy.
High energy magnetic excitations
International Nuclear Information System (INIS)
Endoh, Yasuo
1988-01-01
The report emphasizes that the current development in condensed matter physics opens a research field fit to inelastic neutron scattering experiments in the eV range which is easilly accessed by spallation neutron sources. Several important subjects adopted at thermal reactors are shown. It is desired to extend the implementation of the spectroscopic experiments for investigation of higher energy magnetic excitations. For La 2 CuO 4 , which is the mother crystal of the first high Tc materials found by Bednortz and Muller, it seems to be believed that the magnetism is well characterized by the two-dimensional Heisenberg antiferromagnetic Hamiltonian, and it is widely accepted that the magnetism is a most probable progenitor of high Tc superconductors. The unusual properties of spin correlations in this crystal have been studied extensively by standard neutron scattering techniques with steady neutrons at BNL. FeSi is not ordered magnetically but shows a very unique feature of temperature induced magnetism, which also has been studied extensively by using the thermal neutron scattering technique at BNL. In these experiments, polarized neutrons are indispensable to extract the clean magnetic components out of other components of non-magnetic scattering. (N.K.)
Mean excitation energies for molecular ions
DEFF Research Database (Denmark)
Jensen, Phillip W.K.; Sauer, Stephan P.A.; Oddershede, Jens
2017-01-01
The essential material constant that determines the bulk of the stopping power of high energy projectiles, the mean excitation energy, is calculated for a range of smaller molecular ions using the RPA method. It is demonstrated that the mean excitation energy of both molecules and atoms increase...
International Nuclear Information System (INIS)
Purkait, M.
2009-01-01
Double-electron excitation processes of helium atoms by proton and antiproton impact have been theoretically investigated using the four-body formalism of boundary corrected continuum intermediate state (BCCIS-4B) approximation in the energy range of 50-500 keV. In this formalism, the presence of the projectile in the exit channels is described by distorting the final bound state wave functions with coulomb waves (associated with the projectile-electron interactions). The results are in good agreement with the other theoretical and experimental results. Reasonably better agreements have been found in the intermediate and high energy regions. Contributions to the cross section of the different magnetic sub-shells are also analysed.
Stener, M; Bolognesi, P; Coreno, M; O'Keeffe, P; Feyer, V; Fronzoni, G; Decleva, P; Avaldi, L; Kivimäki, A
2011-05-07
Photoabsorption and S 2p photoionization of the SF(6) molecule have been studied experimentally and theoretically in the excitation energy range up to 100 eV above the S 2p ionization potentials. In addition to the well-known 2t(2g) and 4e(g) shape resonances, the spin-orbit-resolved S 2p photoionization cross sections display two weak resonances between 200 and 210 eV, a wide resonance around 217 eV, a Fano-type resonance around 240 eV, and a second wide resonance around 260 eV. Calculations based on time-dependent density functional theory allow us to assign the 217-eV and 260-eV features to the shape resonances in S 2p photoionization. The Fano resonance is caused by the interference between the direct S 2p photoionization channel and the resonant channel that results from the participator decay of the S 2s(-1)6t(1u) excited state. The weak resonances below 210-eV photon energy, not predicted by theory, are tentatively suggested to originate from the coupling between S 2p shake-up photoionization and S 2p single-hole photoionization. The experimental and calculated angular anisotropy parameters for S 2p photoionization are in good agreement.
International Nuclear Information System (INIS)
Usman, Ahmed Rufai; Khandaker, Mayeen Uddin; Haba, Hiromitsu; Otuka, Naohiko; Murakami, Masashi
2017-01-01
Highlights: • Detailed presentation of new results on experimental cross-sections of "n"a"tTi(α,x) processes. • Calculations of thick target yields for scandium and other radionuclides via the "n"a"tTi(α,x) production route. • Comparison with TENDL-2015 library. • Detailed review of previous experimental data. - Abstract: We studied the excitation functions of residual radionuclide productions from α particles bombardment on natural titanium in the energy range of 10.4–50.2 MeV. A well-established stacked-foil activation technique combined with HPGe γ-ray spectrometry was used to measure the excitation functions for the "5"1","4"9","4"8Cr, "4"8V, "4"3K, and "4"3","4"4"m","4"4"g","4"6"g"+"m","4"7","4"8Sc radionuclides. The thick target yields for all assessed radionuclides were also calculated. The obtained experimental data were compared with the earlier experimental ones and also with the evaluated data in the TENDL-2015 library. A reasonable agreement was found between this work and some of the previous ones, while a partial agreement was found with the evaluated data. The present results would further enrich the experimental database and facilitate the understanding of existing discrepancies among the previous measurements. The results would also help to enhance the prediction capability of the nuclear reaction model codes.
Energy Technology Data Exchange (ETDEWEB)
Usman, Ahmed Rufai [Department of Physics, University of Malaya, 50603 Kuala Lumpur (Malaysia); Nishina Center for Accelerator-Based Science, RIKEN, Wako, Saitama 351-0198 (Japan); Department of Physics, Umaru Musa Yar' adua University, Katsina (Nigeria); Khandaker, Mayeen Uddin, E-mail: mu_khandaker@um.edu.my [Department of Physics, University of Malaya, 50603 Kuala Lumpur (Malaysia); Haba, Hiromitsu [Nishina Center for Accelerator-Based Science, RIKEN, Wako, Saitama 351-0198 (Japan); Otuka, Naohiko [Nuclear Data Section, Division of Physical and Chemical Sciences, Department of Nuclear Sciences and Applications, International Atomic Energy Agency, A-1400 Vienna (Austria); Murakami, Masashi [Nishina Center for Accelerator-Based Science, RIKEN, Wako, Saitama 351-0198 (Japan)
2017-05-15
Highlights: • Detailed presentation of new results on experimental cross-sections of {sup nat}Ti(α,x) processes. • Calculations of thick target yields for scandium and other radionuclides via the {sup nat}Ti(α,x) production route. • Comparison with TENDL-2015 library. • Detailed review of previous experimental data. - Abstract: We studied the excitation functions of residual radionuclide productions from α particles bombardment on natural titanium in the energy range of 10.4–50.2 MeV. A well-established stacked-foil activation technique combined with HPGe γ-ray spectrometry was used to measure the excitation functions for the {sup 51,49,48}Cr, {sup 48}V, {sup 43}K, and {sup 43,44m,44g,46g+m,47,48}Sc radionuclides. The thick target yields for all assessed radionuclides were also calculated. The obtained experimental data were compared with the earlier experimental ones and also with the evaluated data in the TENDL-2015 library. A reasonable agreement was found between this work and some of the previous ones, while a partial agreement was found with the evaluated data. The present results would further enrich the experimental database and facilitate the understanding of existing discrepancies among the previous measurements. The results would also help to enhance the prediction capability of the nuclear reaction model codes.
Excitation function of ''7''4Ge(n, α)''7''1''mZn reaction in the energy range 13.82-14.70 MeV
International Nuclear Information System (INIS)
Halim, M.A.; Hafiz, M.A.; Naher, K.; Miah, R.U.; Ullah, M.R.
2003-01-01
The excitation function of the reaction ''7''4Ge(n, α)''7''1''mZn is measured by activation technique using high resolution HPGe detector gamma ray spectroscopy. Monoenergetic neutrons are produced via D-T reaction at J-25 neutron generator facility of the Institute of Nuclear Science and Technology, AERE, Bangladesh. The neutron flux measurement was done at different energy position in the range 13.82-14.70 MeV using the monitor reaction ''2''7Al(n, α)''2''4Na. The measured cross section values along with the literature data are plotted as a function of neutron energy to get the excitation function of the reaction. A theoretical calculation is also performed to produce the excitation function of the investigated reaction using statistical code SINCROS-II. The measured data are to be found to be in good agreement with the literature data and the theoretical cross section values. (author)
International Nuclear Information System (INIS)
Chakrabarty, D.R.; Eswaran, M.A.; Ragoowansi, N.L.
1983-01-01
The α capture reaction 32 S(α,γ) 36 Ar was studied in the bombarding energy range of E/sub α/ = 4.13 to 5.00 MeV corresponding to the excitation energy range of E/sub x/ = 10.31 to 11.08 MeV in 36 Ar. Seven resonances have been located and their resonance strengths determined. Two of the resonances decay predominantly to the ground state while the other five decay predominantly to the first excited state of 36 Ar. Angular distribution measurements of the predominant decay gamma ray have been performed and the spin and parity of all the resonances assigned. The isospin of two of the resonances have been assigned as T = 0 while T = 1 has been assigned for three others. Evidence has been obtained for the operation of the isospin selection rule for the dipole (E1 and M1) and quadrupole (E2) gamma decay
Energy Technology Data Exchange (ETDEWEB)
Gao, Li-Na; Liu, Fu-Hu [Shanxi University, Institute of Theoretical Physics, Taiyuan, Shanxi (China); Sun, Yan; Sun, Zhu [Shanxi Datong University, Department of Physics, Datong, Shanxi (China); Lacey, Roy A. [Stony Brook University, Departments of Chemistry and Physics, Stony Brook, NY (United States)
2017-03-15
Experimental results of the rapidity spectra of protons and net-protons (protons minus antiprotons) emitted in gold-gold (Au-Au) and lead-lead (Pb-Pb) collisions, measured by a few collaborations at the alternating gradient synchrotron (AGS), super proton synchrotron (SPS), and relativistic heavy ion collider (RHIC), are described by a three-source distribution. The values of the distribution width σ{sub C} and fraction k{sub C} of the central rapidity region, and the distribution width σ{sub F} and rapidity shift Δy of the forward/backward rapidity regions, are then obtained. The excitation function of σ{sub C} increases generally with increase of the center-of-mass energy per nucleon pair √(s{sub NN}). The excitation function of σ{sub F} shows a saturation at √(s{sub NN}) = 8.8 GeV. The excitation function of k{sub C} shows a minimum at √(s{sub NN}) = 8.8 GeV and a saturation at √(s{sub NN}) ∼ 17 GeV. The excitation function of Δy increases linearly with ln(√(s{sub NN})) in the considered energy range. (orig.)
Energy dependence of the ionization of highly excited atoms by collisions with excited atoms
International Nuclear Information System (INIS)
Shirai, T.; Nakai, Y.; Nakamura, H.
1979-01-01
Approximate analytical expressions are derived for the ionization cross sections in the high- and low-collision-energy limits using the improved impulse approximation based on the assumption that the electron-atom inelastic-scattering amplitude is a function only of the momentum transfer. Both cases of simultaneous excitation and de-excitation of one of the atoms are discussed. The formulas are applied to the collisions between two excited hydrogen atoms and are found very useful for estimating the cross sections in the wide range of collisions energies
Excitation methods for energy dispersive analysis
International Nuclear Information System (INIS)
Jaklevic, J.M.
1976-01-01
The rapid development in recent years of energy dispersive x-ray fluorescence analysis has been based primarily on improvements in semiconductor detector x-ray spectrometers. However, the whole analysis system performance is critically dependent on the availability of optimum methods of excitation for the characteristic x rays in specimens. A number of analysis facilities based on various methods of excitation have been developed over the past few years. A discussion is given of the features of various excitation methods including charged particles, monochromatic photons, and broad-energy band photons. The effects of the excitation method on background and sensitivity are discussed from both theoretical and experimental viewpoints. Recent developments such as pulsed excitation and polarized photons are also discussed
International Nuclear Information System (INIS)
Inokuti, M.
1984-01-01
Consider the intensity of absorption of a photon (i.e., the photoabsorption cross section) as a function of photon energy E. Apart from some intensity related to pure nuclear motion and spins, the (electronic) absorption begins at several eV (i.e., in the visible region or the near ultraviolet region). It becomes stronger at tens of eV's (i.e., in the far ultraviolet), and gradually diminishes at higher E. However, the intensity enhances again as E becomes comparable to an inner-shell binding energy. This repeats throughout the x-ray region until E greatly exceeds the K-shell binding energy. I shall discuss the gross variation of the absorption intensity with E. This intensity, suitably normalized, is the oscillator-strength distribution df/dE
High energy excitations in itinerant ferromagnets
International Nuclear Information System (INIS)
Prange, R.E.
1984-01-01
Itinerant magnets, those whose electrons move throughout the crystal, are described by band theory. Single particle excitations offer confirmation of band theory, but their description requires important corrections. The energetics of magnetism in iron and nickel is also described in band theory but requires complex bands. Magnetism above the critical temperature and the location of the critical temperature offer discriminants between the two major models of magnetism at high temperature and can be addressed by high energy excitations
The Mean Excitation Energy of Atomic Ions
DEFF Research Database (Denmark)
Sauer, Stephan; Oddershede, Jens; Sabin, John R.
2015-01-01
A method for calculation of the mean excitation energies of atomic ions is presented, making the calculation of the energy deposition of fast ions to plasmas, warm, dense matter, and complex biological systems possible. Results are reported to all ions of helium, lithium, carbon, neon, aluminum...
Hot nuclei, limiting temperatures and excitation energies
International Nuclear Information System (INIS)
Peter, J.
1986-09-01
Hot fusion nuclei are produced in heavy ion collisions at intermediate energies (20-100 MeV/U). Information on the maximum excitation energy per nucleon -and temperatures- indicated by the experimental data is compared to the predictions of static and dynamical calculations. Temperatures around 5-6 MeV are reached and seem to be the limit of formation of thermally equilibrated fusion nuclei
A scalable piezoelectric impulse-excited energy harvester for human body excitation
International Nuclear Information System (INIS)
Pillatsch, P; Yeatman, E M; Holmes, A S
2012-01-01
Harvesting energy from low-frequency and non-harmonic excitations typical of human motion presents specific challenges. While resonant devices do have an advantage in environments where the excitation frequency is constant, and while they can make use of the entire proof mass travel range in the case of excitation amplitudes that are smaller than the internal displacement limit, they are not suitable for body applications since the frequencies are random and the amplitudes tend to be larger than the device size. In this paper a piezoelectric, impulse-excited approach is presented. A cylindrical proof mass actuates an array of piezoelectric bi-morph beams through magnetic attraction. After the initial excitation these transducers are left to vibrate at their natural frequency. This increases the operational frequency range as well as the electromechanical coupling. The principle of impulse excitation is discussed and a centimetre-scale functional model is introduced as a proof of concept. The obtained data show the influence of varying the frequency, acceleration and proof mass. Finally, a commercially available integrated circuit for voltage regulation is tested. At a frequency of 2 Hz and an acceleration of 2.7 m s −2 a maximal power output of 2.1 mW was achieved. (paper)
International Nuclear Information System (INIS)
Goncharov, A.
2014-01-01
The goal of this work is measurement of differential cross sections for the production of 378 keV γ-rays from the reactions 52 Cr(p,γ1) 53 Mn and 53 Cr(p,nγ1) 53 Mn for proton energies ranging between 1.0 and 3.0 MeV at the laboratory angle of 90° using foils with thickness ∼1.9×10 18 at/cm 2 (∼ 0.23 μm) of nat Cr.
Highly excited bound-state resonances of short-range inverse power-law potentials
Energy Technology Data Exchange (ETDEWEB)
Hod, Shahar [The Ruppin Academic Center, Emeq Hefer (Israel); The Hadassah Academic College, Jerusalem (Israel)
2017-11-15
We study analytically the radial Schroedinger equation with long-range attractive potentials whose asymptotic behaviors are dominated by inverse power-law tails of the form V(r) = -β{sub n}r{sup -n} with n > 2. In particular, assuming that the effective radial potential is characterized by a short-range infinitely repulsive core of radius R, we derive a compact analytical formula for the threshold energy E{sub l}{sup max} = E{sub l}{sup max}(n, β{sub n}, R), which characterizes the most weakly bound-state resonance (the most excited energy level) of the quantum system. (orig.)
Excitation-energy influence at the scission configuration
Directory of Open Access Journals (Sweden)
Ramos D.
2017-01-01
Full Text Available Transfer- and fusion-induced fission in inverse kinematics was proven to be a powerful tool to investigate nuclear fission, widening the information of the fission fragments and the access to unstable fissioning systems with respect to other experimental approaches. An experimental campaign for fission investigation has being carried out at GANIL with this technique since 2008. In these experiments, a beam of 238U, accelerated to 6.1 MeV/u, impinges on a 12C target. Fissioning systems from U to Cf are populated through transfer and fusion reactions, with excitation energies that range from few MeV up to 46 MeV. The use of inverse kinematics, the SPIDER telescope, and the VAMOS spectrometer permitted the characterization of the fissioning system in terms of mass, nuclear charge, and excitation energy, and the isotopic identification of the full fragment distribution. The neutron excess, the total neutron multiplicity, and the even-odd staggering in the nuclear charge of fission fragments are presented as a function of the excitation energy of the fissioning system. Structure effects are observed at Z∼50 and Z∼55, where their impact evolves with the excitation energy.
Neutron scattering investigation of magnetic excitations at high energy transfers
International Nuclear Information System (INIS)
Loong, C.K.
1984-01-01
With the advance of pulsed spallation neutron sources, neutron scattering investigation of elementary excitations in magnetic materials can now be extended to energies up to several hundreds of MeV. We have measured, using chopper spectrometers and time-of-flight techniques, the magnetic response functions of a series of d and f transition metals and compounds over a wide range of energy and momentum transfer. In PrO 2 , UO 2 , BaPrO 3 and CeB 6 we observed crystal-field transitions between the magnetic ground state and the excited levels in the energy range from 40 to 260 MeV. In materials exhibiting spin-fluctuation or mixed-valent character such as Ce 74 Th 26 , on the other hand, no sharp crystal-field lines but a broadened quasielastic magnetic peak was observed. The line width of the quasielastic component is thought to be connected to the spin-fluctuation energy of the 4f electrons. The significance of the neutron scattering results in relation to the ground state level structure of the magnetic ions and the spin-dynamics of the f electrons is discussed. Recently, in a study of the spin-wave excitations in itinerant magnetic systems, we have extended the spin-wave measurements in ferromagnetic iron up to about 160 MeV. Neutron scattering data at high energy transfers are of particular interest because they provide direct comparison with recent theories of itinerant magnetism. 26 references, 7 figures
Energy Technology Data Exchange (ETDEWEB)
Zou, Y [Key Laboratory of Applied Ion Beam Physics (Chinese Educational Ministry), Fudan University, Shanghai 200433 (China); Oura, M [RIKEN Spring-8 Center, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5148 (Japan); Hutton, R [Lund Observatory, SE-221 00 Lund (Sweden); Yamaoka, H [RIKEN Spring-8 Center, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5148 (Japan); Takeshima, N [Department of Chemistry and Materials Technology, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto 606-8585 (Japan); Takahiro, K [Department of Chemistry and Materials Technology, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto 606-8585 (Japan); Kawatsura, K [Department of Chemistry and Materials Technology, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto 606-8585 (Japan); Mukoyama, T [Kansai Gaidai University, 16-1 Nakamiyahigashino-cho, Hirakata, Osaka 573-1001 (Japan)
2006-11-28
Photoinduced Ba L x-rays were measured, in the excitation energy range of 5.6-30 keV, by using high-brilliance undulator radiation. The obtained intensity ratios, the excitation-energy independent L{beta}{sub 4}/L{beta}{sub 3}, L{eta}/L{beta}{sub 1}, L{iota}/L{alpha}{sub 1,2}, L{beta}{sub 6}/L{alpha}{sub 1,2} and L{beta}{sub 2,15}/L{alpha}{sub 1,2} as well as the excitation-energy dependent L{beta}{sub 1}/L{alpha}{sub 1,2}, L{beta}{sub 3}/L{alpha}{sub 1,2} and L{beta}{sub 3}/L{beta}{sub 1}, were compared with theoretical calculations, in which the calculations were performed by applying various subsets of the L subshell fluorescence yields and Coster-Kronig yields. Deviations of the theoretical calculations from the experimental results call on improvements in theory for the emission rates. We have also surveyed the L{alpha}{sub 1,2} related x-ray hypersatellite lines in the photoinduced Ba L x-ray spectrum.
Integrated light in direct excitation and energy transfer luminescence
Chimczak, Eugeniusz
2007-01-01
Integrated light in direct excitation and energy transfer luminescence has been investigated. In the investigations reported here, monomolecular centers were taken into account. It was found that the integrated light is equal to the product of generation rate and time of duration of excitation pulse for both direct excitation and energy transfer luminescence.
Alam, Md. Mehboob; Deur, Killian; Knecht, Stefan; Fromager, Emmanuel
2017-11-01
The extrapolation technique of Savin [J. Chem. Phys. 140, 18A509 (2014)], which was initially applied to range-separated ground-state-density-functional Hamiltonians, is adapted in this work to ghost-interaction-corrected (GIC) range-separated ensemble density-functional theory (eDFT) for excited states. While standard extrapolations rely on energies that decay as μ-2 in the large range-separation-parameter μ limit, we show analytically that (approximate) range-separated GIC ensemble energies converge more rapidly (as μ-3) towards their pure wavefunction theory values (μ → +∞ limit), thus requiring a different extrapolation correction. The purpose of such a correction is to further improve on the convergence and, consequently, to obtain more accurate excitation energies for a finite (and, in practice, relatively small) μ value. As a proof of concept, we apply the extrapolation method to He and small molecular systems (viz., H2, HeH+, and LiH), thus considering different types of excitations such as Rydberg, charge transfer, and double excitations. Potential energy profiles of the first three and four singlet Σ+ excitation energies in HeH+ and H2, respectively, are studied with a particular focus on avoided crossings for the latter. Finally, the extraction of individual state energies from the ensemble energy is discussed in the context of range-separated eDFT, as a perspective.
General theory for environmental effects on (vertical) electronic excitation energies.
Schwabe, Tobias
2016-10-21
Almost 70 years ago, the first theoretical model for environmental effects on electronic excitation energies has been derived. Since then, several different interpretations and refined models have been proposed for the perichromic shift of a chromophore due to its surrounding medium. Some of these models are contradictory. Here, the contributing terms are derived within the framework of long-range perturbation theory with the least approximations so far. The derivation is based on a state-specific interpretation of the interaction energies and all terms can be identified with individual properties of either the chromophore or the surroundings, respectively. Further, the much debated contribution due to transition moments coupled to the environment can be verified in the form of a non-resonant excitonic coupling to the dynamic polarizabilities in the environment. These general insights should clarify discussions and interpretations of environmental effects on electronic excitations and should foster the development of new models for the computation of these effects.
Experimental determination of fragment excitation energies in multifragmentation events
International Nuclear Information System (INIS)
Marie, N.; Natowitz, J.B.; Assenard, M.; Bacri, Ch.O.
1998-01-01
For 50 MeV/nucleon 129 Xe + nat Sn multifragmentation events, by means of correlation techniques, the multiplicities of the hydrogen and helium isotopes which were emitted by the hot primary excited fragments produced at the stage of the disassembly of an equilibrated hot source are determined. The relative kinetic energy distributions between the primary clusters and the light charged particles that they evaporate are also derived. From the comparison between the secondary multiplicities observed experimentally and the multiplicities predicted by the GEMINI model, it is concluded that the source breaks into primary fragments which are characterized by the same N/Z ratio as the combined system. Knowing the secondary light charged particle multiplicities and kinetic energies, the average charges of the hot fragments and are reconstructed their mean excitation energies are estimated. The fragment excitation energies are equal to 3.0 MeV/nucleon for the full range of intermediate mass fragment atomic number. This global constancy indicates that, on the average, thermodynamical equilibrium was achieved at the disassembly stage of the source. (author)
Experimental determination of fragment excitation energies in multifragmentation events
Energy Technology Data Exchange (ETDEWEB)
Marie, N.; Natowitz, J.B. [Texas A and M Univ., College Station, TX (United States). Cyclotron Inst.; Chbihi, A.; Le Fevre, A.; Salou, S.; Wieleczko, J.P.; Gingras, L.; Auger, G. [Grand Accelerateur National d`Ions Lourds, 14 - Caen (France); Assenard, M. [Nantes Univ., 44 (France); Bacri, Ch.O. [Centre National de la Recherche Scientifique, CNRS, 91 - Orsay (France)] [and others
1998-03-17
For 50 MeV/nucleon {sup 129}Xe + {sup nat}Sn multifragmentation events, by means of correlation techniques, the multiplicities of the hydrogen and helium isotopes which were emitted by the hot primary excited fragments produced at the stage of the disassembly of an equilibrated hot source are determined. The relative kinetic energy distributions between the primary clusters and the light charged particles that they evaporate are also derived. From the comparison between the secondary multiplicities observed experimentally and the multiplicities predicted by the GEMINI model, it is concluded that the source breaks into primary fragments which are characterized by the same N/Z ratio as the combined system. Knowing the secondary light charged particle multiplicities and kinetic energies, the average charges of the hot fragments and are reconstructed their mean excitation energies are estimated. The fragment excitation energies are equal to 3.0 MeV/nucleon for the full range of intermediate mass fragment atomic number. This global constancy indicates that, on the average, thermodynamical equilibrium was achieved at the disassembly stage of the source. (author) 25 refs.
DEFF Research Database (Denmark)
Hedegård, Erik Donovan
2017-01-01
considered the large collection of organic molecules whose excited states were investigated with a range of electronic structure methods by Thiel et al. As a by-product of our calculations of oscillator strengths, we also obtain electronic excitation energies, which enable us to compare the performance......We have in a series of recent papers investigated electronic excited states with a hybrid between a complete active space self-consistent field (CASSCF) wave function and density functional theory (DFT). This method has been dubbed the CAS short-range DFT method (CAS–srDFT). The previous papers...
International Nuclear Information System (INIS)
Frey, R.W.
1978-01-01
Using high resolution inelastic electron scattering magnitic dipole and quadrupole excitations in 208 Pb were investigated in the energy range between 6 MeV and 8 MeV. The electron energy was 50 MeV and 63.5 MeV. With a mean absolute energy resolution of 33 kev. 44 excited states were found in the above energy range. The measured angular distributions were compared with DWBA-calculations using random phase approximated wave functions. (FKS)
Low energy spin excitations in chromium metal
International Nuclear Information System (INIS)
Pynn, R.; Azuah, R.T.; Stirling, W.G.
1997-01-01
Neutron scattering experiments with full polarization analysis have been performed with a single crystal of chromium to study the low-energy spin fluctuations in the transverse spin density wave (TSDW) state. A number of remarkable results have been found. Inelastic scattering observed close to the TSDW satellite positions at (1 ± δ,0,0) does not behave as expected for magnon scattering. In particular, the scattering corresponds to almost equally strong magnetization fluctuations both parallel and perpendicular to the ordered moments of the TSDW phase. As the Neel temperature is approached from below, scattering at the commensurate wavevector (1,0,0) increases in intensity as a result of critical scattering at silent satellites (1,0, ± δ) being included within the spectrometer resolution function. This effect, first observed by Sternlieb et al, does not account for all of the inelastic scattering around the (1,0,0) position, however, Rather, there are further collective excitations, apparently emanating from the TSDW satellites, which correspond to magnetic fluctuations parallel to the ordered TSDW moments. These branches have a group velocity that is close to that of (1,0,0) longitudinal acoustic (LA) phonons, but assigning their origin to magneto-elastic scattering raises other unanswered questions
International Nuclear Information System (INIS)
Yasufuku, H.; Yoshikawa, H.; Kimura, M.; Vlaicu, A.M.; Kato, M.; Kudo, M.; Fujikata, J.; Fukushima, S.
2006-01-01
We have newly developed an x-ray photoemission electron microscope (XPEEM) which uses both soft x-rays and hard x-rays at the undulator beam line BL15XU in the synchrotron radiation (SR) facility SPring-8 to observe various practical materials. In combination with an energy analyzer and high brilliant x-ray source, the detection of high kinetic energy inner-shell photoelectrons is essential for revealing the chemical properties of specimen subsurfaces or buried interfaces, owing to long inelastic mean free path of the high kinetic energy photoelectrons. The most significant result in our design is the new combined electric and magnetic field objective lens in which the magnetic field penetrates up to the sample surface. This allows the measurement with high spatial resolution of both low intensity images of inner-shell photoelectrons with high kinetic energy and high intensity images of secondary electrons. By using the sample bias scan method, we can easily change the focus condition of the objective lens in order to allow the energy filtered imaging with photoelectrons having the kinetic energy in a wide range (1-10 000 eV). By the combination of high brilliant SR x-rays, the new objective lens, and sample bias method, our XPEEM can successfully obtain the microarea x-ray photoelectron spectra and energy filtered XPEEM images of inner-shell photoelectrons, such as Si 1s, without any surface cleaning procedure. The energy filtered XPEEM image using photoelectrons from deep inner shells, Si 1s, was obtained for the first time
International Nuclear Information System (INIS)
Hudan, S.; Chbihi, A.; Frankland, J.D.
2000-01-01
Characteristics of the primary fragments produced in central collisions of Xe + Sn system from 32 to 50 AMeV have been deduced. By using the relative velocity correlation technique between the light charged particles (LCP) and detected fragments, we were able to extract the multiplicities and average kinetic energy of the secondary evaporated LCP. We then reconstructed the size and excitation energy of the primary fragments. For each bombarding energy a constant value of the excitation energy per nucleon, over the whole range of fragment charge has been found, suggesting that on the average thermodynamical equilibrium has been achieved at the freeze-out. This value increases slightly from 2.8 to 3.8 AMeV with a large increase of bombarding energy, 32 to 50 AMeV. (authors)
Energy Technology Data Exchange (ETDEWEB)
Hudan, S.; Chbihi, A.; Frankland, J.D. [Grand Accelerateur National d' Ions Lourds (GANIL), 14 - Caen (France)] [and others
2000-07-01
Characteristics of the primary fragments produced in central collisions of Xe + Sn system from 32 to 50 AMeV have been deduced. By using the relative velocity correlation technique between the light charged particles (LCP) and detected fragments, we were able to extract the multiplicities and average kinetic energy of the secondary evaporated LCP. We then reconstructed the size and excitation energy of the primary fragments. For each bombarding energy a constant value of the excitation energy per nucleon, over the whole range of fragment charge has been found, suggesting that on the average thermodynamical equilibrium has been achieved at the freeze-out. This value increases slightly from 2.8 to 3.8 AMeV with a large increase of bombarding energy, 32 to 50 AMeV. (authors)
Electronic-excitation energy transfer in heterogeneous dye solutions under laser excitation
International Nuclear Information System (INIS)
Levshin, L.V.; Mukushev, B.T.; Saletskii, A.M.
1995-01-01
An experimental study has been made of electronic-excitation energy transfer (EEET) among dye molecules of different types for different exciting-fight wavelengths and temperatures. Upon selective laser excitation of the donor, the inhomogeneous broadening of molecular levels increases the probability of EEET from the donor to acceptor molecules. The efficiency of this process is directly proportional to the acceptor molecule concentration and is temperature dependent. The EEET is accompanied by the spectral migration of energy among donor molecules, which reduces the fluorescence quantum efficiency of the donor. Increasing the frequency of the exciting light decreases in the donor fluorescence quantum efficiency. An increase in the acceptor molecule concentration results in a decrease of the spectral migration of excitation in the donor molecule system. 5 refs., 5 figs
International Nuclear Information System (INIS)
Frascaria, N.
1987-09-01
A review of experimental results on high excitation energy structures in heavy ion inelastic scattering is presented. The contribution to the spectra of the pick-up break-up mechanism is discussed in the light of the data obtained with light heavy ion projectiles. Recent results obtained with 40 Ar beams at various energies will show that target excitations contribute strongly to the measured cross section
Long range energy transfer in graphene hybrid structures
International Nuclear Information System (INIS)
Gonçalves, Hugo; Bernardo, César; Moura, Cacilda; Belsley, Michael; Schellenberg, Peter; Ferreira, R A S; André, P S; Stauber, Tobias
2016-01-01
In this work we quantify the distance dependence for the extraction of energy from excited chromophores by a single layer graphene flake over a large separation range. To this end hybrid structures were prepared, consisting of a thin (2 nm) layer of a polymer matrix doped with a well chosen strongly fluorescent organic molecule, followed by an un-doped spacer layer of well-defined thicknesses made of the same polymer material and an underlying single layer of pristine, undoped graphene. The coupling strength is assessed through the variation of the fluorescence decay kinetics as a function of distance between the graphene and the excited chromophore molecules. Non-radiative energy transfer to the graphene was observed at distances of up to 60 nm; a range much greater than typical energy transfer distances observed in molecular systems. (paper)
Study of excitation energy dependence of nuclear level density parameter
International Nuclear Information System (INIS)
Mohanto, G.; Nayak, B.K.; Saxena, A.
2016-01-01
In the present study, we have populated CN by fusion reaction and excitation energy of the intermediate nuclei is determined after first chance α-emission to investigate excitation energy dependence of the NLD parameter. Evaporated neutron spectra were measured following alpha evaporation for obtaining NLD parameter for the reaction 11 B + 197 Au, populating CN 208 Po. This CN after evaporating an α-particle populates intermediate nucleus 204 Pb. The 204 Pb has magic number of Z=82. Our aim is to study the excitation energy dependence of NLD parameter for closed shell nuclei
On the determination of the mean excitation energy of water
DEFF Research Database (Denmark)
Sabin, John R.; Oddershede, Jens; Sauer, Stephan P. A.
2013-01-01
Water is a ubiquitous substance in nature, and thus the mean excitation energy of water is an important quantity for understanding and prediction of the details of many fast ion/molecule collision processes such as those involved in external beam radiotherapy of tumors. There are several methods...... for determining numerical values for a mean excitation energy for water, both theoretical and experimental. Here the factors affecting the determination of the value of the mean excitation energy of water, especially from experiment, are discussed....
Dependence of the giant dipole strength function on excitation energy
International Nuclear Information System (INIS)
Draper, J.E.; Newton, J.O.; Sobotka, L.G.; Lindenberger, H.; Wozniak, G.J.; Moretto, L.G.; Stephens, F.S.; Diamond, R.M.; McDonald, R.J.
1982-01-01
Spectra of γ rays associated with deep-inelastic products from the 1150-MeV 136 Xe+ 181 Ta reaction have been measured. The yield of 10--20-MeV γ rays initially increases rapidly with the excitation energy of the products and then more slowly for excitation energies in excess of 120 MeV. Statistical-model calculations with ground-state values of the giant dipole strength function fail to reproduce the shape of the measured γ-ray spectra. This suggests a dependence of the giant dipole strength function on excitation energy
DEFF Research Database (Denmark)
Senjean, Bruno; Knecht, Stefan; Jensen, Hans Jørgen Aa
2015-01-01
Gross-Oliveira-Kohn density-functional theory (GOK-DFT) for ensembles is, in principle, very attractive but has been hard to use in practice. A practical model based on GOK-DFT for the calculation of electronic excitation energies is discussed. The model relies on two modifications of GOK-DFT: use...... promising results have been obtained for both single (including charge transfer) and double excitations with spin-independent short-range local and semilocal functionals. Even at the Kohn-Sham ensemble DFT level, which is recovered when the range-separation parameter is set to 0, LIM performs better than...
Roles of the Excitation in Harvesting Energy from Vibrations.
Directory of Open Access Journals (Sweden)
Hui Zhang
Full Text Available The study investigated the role of excitation in energy harvesting applications. While the energy ultimately comes from the excitation, it was shown that the excitation may not always behave as a source. When the device characteristics do not perfectly match the excitation, the excitation alternately behaves as a source and a sink. The extent to which the excitation behaves as a sink determines the energy harvesting efficiency. Such contradictory roles were shown to be dictated by a generalized phase defined as the instantaneous phase angle between the velocity of the device and the excitation. An inductive prototype device with a diamagnetically levitated seismic mass was proposed to take advantage of the well established phase changing mechanism of vibro-impact to achieve a broader device bandwidth. Results suggest that the vibro-impact can generate an instantaneous, significant phase shift in response velocity that switches the role of the excitation. If introduced properly outside the resonance zone it could dramatically increase the energy harvesting efficiency.
Spectroscopic probes of vibrationally excited molecules at chemically significant energies
Energy Technology Data Exchange (ETDEWEB)
Rizzo, T.R. [Univ. of Rochester, NY (United States)
1993-12-01
This project involves the application of multiple-resonance spectroscopic techniques for investigating energy transfer and dissociation dynamics of highly vibrationally excited molecules. Two major goals of this work are: (1) to provide information on potential energy surfaces of combustion related molecules at chemically significant energies, and (2) to test theoretical modes of unimolecular dissociation rates critically via quantum-state resolved measurements.
Design and development of a parametrically excited nonlinear energy harvester
International Nuclear Information System (INIS)
Yildirim, Tanju; Ghayesh, Mergen H.; Li, Weihua; Alici, Gursel
2016-01-01
Highlights: • A parametrically broadband energy harvester was fabricated. • Strong softening-type nonlinear behaviour was observed. • Experiments were conducted showing the large bandwidth of the device. - Abstract: An energy harvester has been designed, fabricated and tested based on the nonlinear dynamical response of a parametrically excited clamped-clamped beam with a central point-mass; magnets have been used as the central point-mass which pass through a coil when parametrically excited. Experiments have been conducted for the energy harvester when the system is excited (i) harmonically near the primary resonance; (ii) harmonically near the principal parametric resonance; (iii) by means of a non-smooth periodic excitation. An electrodynamic shaker was used to parametrically excite the system and the corresponding displacement of the magnet and output voltages of the coil were measured. It has been shown that the system displays linear behaviour at the primary resonance; however, at the principal parametric resonance, the motion characteristic of the magnet substantially changed displaying a strong softening-type nonlinearity. Theoretical simulations have also been conducted in order to verify the experimental results; the comparison between theory and experiment were within very good agreement of each other. The energy harvester developed in this paper is capable of harvesting energy close to the primary resonance as well as the principal parametric resonance; the frequency-band has been broadened significantly mainly due to the nonlinear effects as well as the parametric excitation.
Identification of the low-energy excitations in a quantum critical system
Directory of Open Access Journals (Sweden)
Tom Heitmann
2017-05-01
Full Text Available We have identified low-energy magnetic excitations in a doped quantum critical system by means of polarized neutron scattering experiments. The presence of these excitations could explain why Ce(Fe0.76Ru0.242Ge2 displays dynamical scaling in the absence of local critical behavior or long-range spin-density wave criticality. The low-energy excitations are associated with the reorientations of the superspins of fully ordered, isolated magnetic clusters that form spontaneously upon lowering the temperature. The system houses both frozen clusters and dynamic clusters, as predicted by Hoyos and Vojta [Phys. Rev. B 74, 140401(R (2006].
Excitation and photon decay of giant resonances excited by intermediate energy heavy ions
International Nuclear Information System (INIS)
Bertrand, F.E.; Beene, J.R.
1987-01-01
Inelastic scattering of medium energy heavy ions provides very large cross sections and peak-to-continuum ratios for excitation of giant resonances. For energies above about 50 MeV/nucleon, giant resonances are excited primarily through Coulomb excitation, which is indifferent to isospin, thus providing a good probe for the study of isovector giant resonances. The extremely large cross sections available from heavy ion excitation permit the study of rare decay modes of the giant resonances. In particular, recent measurements have been made of the photon decay of giant resonances following excitation by 22 and 84 MeV/nucleon 17 O projectiles. The singles results at 84 MeV/nucleon yield peak cross sections for the isoscalar giant quadrupole resonance and the isovector giant dipole resonance of approximately 0.8 and 3 barns/sr, respectively. Data on the ground state decay of the isoscalar giant quadrupole and isovector giant dipole resonances are presented and compared with calculations. Decays to low-lying excited states are also discussed. Preliminary results from an experiment to isolate the 208 Pb isovector quadrupole resonance using its gamma decay are presented. 22 refs., 19 figs., 1 tab
Vibrational excitation of D2 by low energy electrons
International Nuclear Information System (INIS)
Buckman, S.J.; Phelps, A.V.
1985-01-01
Excitation coefficients for the production of vibrationally exicted D 2 by low energy electrons have been determined from measurements of the intensity of infrared emission from mixtures of D 2 and small concentrations of CO 2 or CO. The measurements were made using the electron drift tube technique and covered electric field to gas density ratios (E/n) from (5 to 80) x 10 -21 V m 2 , corresponding to mean electron energies between 0.45 and 4.5 eV. The CO 2 and CO concentrations were chosen to allow efficient excitation transfer from the D 2 to the carbon containing molecule, but to minimize direct excitation of the CO 2 or CO. The measured infrared intensities were normalized to predicted values for N 2 --CO 2 and N 2 --CO mixtures at E/n where the efficiency of vibrational excitation is known to be very close to 100%. The experimental excitation coefficients are in satisfactory agreement with predictions based on electron--D 2 cross sections at mean electron energies below 1 eV, but are about 50% too high at mean energies above about 2 eV. Application of the technique to H 2 did not yield useful vibrational excitation coefficients. The effective coefficients in H 2 --CO 2 mixtures were a factor of about 3 times the predicted values. For our H 2 --CO mixtures the excitation of CO via excitation transfer from H 2 is small compared to direct electron excitation of CO molecules. Published experiments and theories on electron--H 2 and electron--D 2 collisions are reviewed to obtain the cross sections used in the predictions
Energy Technology Data Exchange (ETDEWEB)
Egidi, Franco, E-mail: franco.egidi@sns.it; Segado, Mireia; Barone, Vincenzo, E-mail: vincenzo.barone@sns.it [Scuola Normale Superiore, Piazza dei Cavalieri, 7 I-56126 Pisa (Italy); Koch, Henrik [Department of Chemistry, Norwegian University of Science and Technology, 7491 Trondheim (Norway); Cappelli, Chiara [Dipartimento di Chimica e Chimica Industriale, Università di Pisa, via G. Moruzzi, 3 I-56124 Pisa (Italy)
2014-12-14
In this work, we report a comparative study of computed excitation energies, oscillator strengths, and excited-state energy gradients of (S)-nicotine, chosen as a test case, using multireference methods, coupled cluster singles and doubles, and methods based on time-dependent density functional theory. This system was chosen because its apparent simplicity hides a complex electronic structure, as several different types of valence excitations are possible, including n-π{sup *}, π-π{sup *}, and charge-transfer states, and in order to simulate its spectrum it is necessary to describe all of them consistently well by the chosen method.
Energy-optimal electrical excitation of nerve fibers.
Jezernik, Saso; Morari, Manfred
2005-04-01
We derive, based on an analytical nerve membrane model and optimal control theory of dynamical systems, an energy-optimal stimulation current waveform for electrical excitation of nerve fibers. Optimal stimulation waveforms for nonleaky and leaky membranes are calculated. The case with a leaky membrane is a realistic case. Finally, we compare the waveforms and energies necessary for excitation of a leaky membrane in the case where the stimulation waveform is a square-wave current pulse, and in the case of energy-optimal stimulation. The optimal stimulation waveform is an exponentially rising waveform and necessitates considerably less energy to excite the nerve than a square-wave pulse (especially true for larger pulse durations). The described theoretical results can lead to drastically increased battery lifetime and/or decreased energy transmission requirements for implanted biomedical systems.
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.
Energy Technology Data Exchange (ETDEWEB)
Do, T. P. T. [School of Chemical and Physical Sciences, Flinders University, GPO Box 2100, Adelaide, South Australia 5001 (Australia); School of Education, Can Tho University, Campus II, 3/2 Street, Xuan Khanh, Ninh Kieu, Can Tho City (Viet Nam); Duque, H. V. [School of Chemical and Physical Sciences, Flinders University, GPO Box 2100, Adelaide, South Australia 5001 (Australia); Departamento de Física, Universidade Federal de Juiz de Fora, 36036-330 Juiz de Fora, Minas Gerais (Brazil); Lopes, M. C. A. [Departamento de Física, Universidade Federal de Juiz de Fora, 36036-330 Juiz de Fora, Minas Gerais (Brazil); Konovalov, D. A.; White, R. D. [College of Science, Technology and Engineering, James Cook University, Townsville (Australia); Brunger, M. J., E-mail: michael.brunger@flinders.edu.au, E-mail: darryl.jones@flinders.edu.au [School of Chemical and Physical Sciences, Flinders University, GPO Box 2100, Adelaide, South Australia 5001 (Australia); Institute of Mathematical Sciences, University of Malaya, 50603 Kuala Lumpur (Malaysia); Jones, D. B., E-mail: michael.brunger@flinders.edu.au, E-mail: darryl.jones@flinders.edu.au [School of Chemical and Physical Sciences, Flinders University, GPO Box 2100, Adelaide, South Australia 5001 (Australia)
2015-03-28
We report differential cross sections (DCSs) for electron-impact vibrational-excitation of tetrahydrofuran, at intermediate incident electron energies (15-50 eV) and over the 10°-90° scattered electron angular range. These measurements extend the available DCS data for vibrational excitation for this species, which have previously been obtained at lower incident electron energies (≤20 eV). Where possible, our data are compared to the earlier measurements in the overlapping energy ranges. Here, quite good agreement was generally observed where the measurements overlapped.
Mean excitation energies for use in Bethe's stopping-power formula
International Nuclear Information System (INIS)
Berger, M.J.; Seltzer, S.M.
1983-01-01
A review has been made of the mean excitation energies that can be derived from the analysis of stopping-power and range measurements, and from semi-empirical dipole oscillator-strength distributions for gases and dielectric-response functions for solids. On the basis of this review, mean excitation energies have been selected for 43 elemental substances and 54 compounds. Additivity rules have also been considered which allow one to estimate the mean excitation energies for compounds for which no direct data are available. These additivity rules are based on the use of mean excitation energies for atomic constituents which, to a certain extent, take into account the effects of chemical binding and physical aggregation
Ultrafast excitation energy transfer from encapsulated quaterrylene to single-walled carbon nanotube
Energy Technology Data Exchange (ETDEWEB)
Koyama, Takeshi, E-mail: koyama@nuap.nagoya-u.ac.jp [Department of Applied Physics, Nagoya University, Chikusa, Nagoya 464-8603 (Japan); Tsunekawa, Takuya [Department of Applied Physics, Nagoya University, Chikusa, Nagoya 464-8603 (Japan); Saito, Takeshi [Research Center for Advanced Carbon Materials, AIST, Tsukuba, Ibaraki 305-8565 (Japan); Asaka, Koji; Saito, Yahachi [Department of Quantum Engineering, Nagoya University, Chikusa, Nagoya 464-8603 (Japan); Kishida, Hideo [Department of Applied Physics, Nagoya University, Chikusa, Nagoya 464-8603 (Japan); Nakamura, Arao [Department of Applied Physics, Nagoya University, Chikusa, Nagoya 464-8603 (Japan); Toyota Physical and Chemical Research Institute, Nagakute, Aichi 480-1192 (Japan)
2016-01-15
We investigate excitation energy transfer from an encapsulated quaterrylene molecule to a single-walled carbon nanotube by means of femtosecond pump-probe spectroscopy. The time constant of energy transfer becomes shorter with increasing average diameter of nanotube: 1.4±0.2 ps for 1.0 nm, 1.1±0.2 ps for 1.4 nm, and 0.4±0.1 ps for 1.8 nm. The observed behavior is discussed considering the distance of less than 1 nm between the molecule and the nanotube wall. - Highlights: • Dynamical properties of excited states in quaterrylene/SWNT composites were studied. • Excitation energy transfer occurs in the time range of 0.4-1.4 ps. • The transfer rate depends on the nanotube diameter, i.e. molecule-nanotube wall distance. • This dependence indicates the feature of excitation energy transfer on the nanoscale.
Energy-dependent collisional deactivation of vibrationally excited azulene
International Nuclear Information System (INIS)
Shi, J.; Barker, J.R.
1988-01-01
Collisional energy transfer parameters for highly vibrationally excited azulene have been deduced from new infrared fluorescence (IRF) emission lifetime data with an improved calibration relating IRF intensity to vibrational energy [J. Shi, D. Bernfeld, and J. R. Barker, J. Chem. Phys. 88, XXXX (1988), preceding paper]. In addition, data from previous experiments [M. J. Rossi, J. R. Pladziewicz, and J. R. Barker, J. Chem. Phys. 78, 6695 (1983)] have been reanalyzed based on the improved calibration. Inversion of the IRF decay curves produced plots of energy decay, which were analyzed to determine , the average energy transferred per collision. Master equation simulations reproduced both the original IRF decays and the deduced energy decays. A third (simple) method of determination agrees well with the other two. The results show to be nearly directly proportional to the vibrational energy of the excited azulene from ∼8000 to 33 000 cm -1 . At high energies, there are indications that the energy dependence may be slightly reduced
Electron emission from materials at low excitation energies
International Nuclear Information System (INIS)
Urma, N.; Kijek, M.; Millar, J.J.
1996-01-01
Full text: An experimental system has been designed and developed with the purpose of measuring the total electron emission yield from materials at low energy excitation. In the first instance the reliability of the system was checked by measuring the total electron emission yield for a well defined surface (aluminium 99.45%). The obtained data was in the expected range given by the literature, and consequently the system will be used further for measuring the total electron yield for a range of materials with interest in the instrumentation industry. We intend to measure the total electron emission yield under electron bombardment as a function of incident electron energy up to 1200 eV, angle of incidence, state of the surface and environment to which the surface has been exposed. Dependence of emission on total electron irradiated dose is also of interest. For many practical application of the 'Secondary Electron Emission', the total electron yield is desired to be as large as possible. The above phenomenon has practical applicability in electron multiplier tube and Scanning electron microscopy - when by means of the variation of the yield of the emitted electrons one may produce visible images of small sample areas. The electron multiplier tube, is a device which utilises the above effect to detect and amplify both single particles and low currents streams of charged particles. The majority of electron tubes use electrons with low energy, hundreds of eV. Not a lot has been published in the literature about this regime and also about the emission when the impinging electrons have small energy, up to 1 KeV. The information obtained from the experimental measurements concerning the total electron emission yield is used to asses the investigated materials as a potential electron emitting surfaces or dynodes in an electron multiplier tube
The EDDA experiment: proton-proton elastic scattering excitation functions at intermediate energies
International Nuclear Information System (INIS)
Hinterberher, F.
1996-01-01
The EDDA experiment is designed to provide a high precision measurement of proton-proton elastic scattering excitation functions ranging from 0.5 to 2.5 GeV of (lab) incident kinetic energy. It is an internal target experiment utilizing the proton beam of the cooler synchrotron COSY operated by KFA Juelich. The excitation functions are measured during the acceleration ramp of COSY. (author)
Realistic level densities in fragment emission at high excitation energies
International Nuclear Information System (INIS)
Mustafa, M.G.; Blann, M.; Ignatyuk, A.V.
1993-01-01
Heavy fragment emission from a 44 100 Ru compound nucleus at 400 and 800 MeV of excitation is analyzed to study the influence of level density models on final yields. An approach is used in which only quasibound shell-model levels are included in calculating level densities. We also test the traditional Fermi gas model for which there is no upper energy limit to the single particle levels. We compare the influence of these two level density models in evaporation calculations of primary fragment excitations, kinetic energies and yields, and on final product yields
DEFF Research Database (Denmark)
Hubert, Mickaël; Hedegård, Erik D.; Jensen, Hans Jørgen Aa
2016-01-01
-srDFT for a selected benchmark set of electronic excitations of organic molecules, covering the most common types of organic chromophores. This investigation confirms the expectation that the MC-srDFT method is accurate for a broad range of excitations and comparable to accurate wave function methods such as CASPT2......Computational methods that can accurately and effectively predict all types of electronic excitations for any molecular system are missing in the toolbox of the computational chemist. Although various Kohn-Sham density-functional methods (KS-DFT) fulfill this aim in some cases, they become...... and double excitations have been promising, it is nevertheless important that the accuracy of MC-srDFT is at least comparable to the best KS-DFT methods also for organic molecules that are typically of single-reference character. In this paper we therefore systematically investigate the performance of MC...
Energies and lifetimes of excited states in copperlike Kr VIII
International Nuclear Information System (INIS)
Livingston, A.E.; Curtis, L.J.; Schectman, R.M.; Berry, H.G.
1980-01-01
The spectrum of Kr VIII has been observed between 180 and 2000 A by using foil excitation of 2.5--3.5-MeV krypton ions. Twenty new transitions have been classified and eleven new excited-state energies have been determined within the n=4 --7 shells. The ionization potential is derived to be 1 015 800 +- 200 cm -1 . The excited-state energies and fine structures are compared with recent relativistic Hartree-Fock calculations. The 4p-state lifetime has been measured by performing a simultaneous analysis of decay data for the 4p level and for its dominant cascade-repopulating levels. The 4p lifetime is found to be 30% shorter than previously measured values and is in excellent agreement with the result of a recent multiconfiguration Hartree-Fock calculation. The source of the discrepancy between this result and earlier measurements is discussed
Long-Range Energy Propagation in Nanometer Arrays of Light Harvesting Antenna Complexes
Escalantet, Maryana; Escalante Marun, M.; Lenferink, Aufrid T.M.; Zhao, Yiping; Tas, Niels Roelof; Huskens, Jurriaan; Hunter, C. Neil; Subramaniam, Vinod; Otto, Cornelis
2010-01-01
Here we report the first observation of long-range transport of excitation energy within a biomimetic molecular nanoarray constructed from LH2 antenna complexes from Rhodobacter sphaeroides. Fluorescence microscopy of the emission of light after local excitation with a diffraction-limited light beam
Glass-like, low-energy excitations in neutron-irradiated quartz
International Nuclear Information System (INIS)
Gardner, J.W.
1980-01-01
The specific heat and thermal conductivity of neutron-irradiated crystalline quartz have been measured for temperatures approx. = 0.1 to 5 K. Four types of low-energy excitations are observed in the irradiated samples, two of which can be removed selectively by heat treatment. One set of remaining excitations gives rise to low-temperature thermal behavior characteristic of glassy (amorphous) solids. The density of these glass-like excitations can be 50% the density observed in vitreous silica, yet the sample still retains long-range atomic order. In a less-irradiated sample, glass-like excitations may be present with a density only approx. = 2.5% that observed in vitreous silica and possess a similar broad energy spectrum over 0.1 to 1 K
Complex fragment emission at low and high excitation energy
International Nuclear Information System (INIS)
Moretto, L.G.
1986-08-01
Complex fragment emission has been certified as a compound nucleus process at low energies. An extension of the measurements to heavy ion reactions up to 50 MeV/u shows that most complex fragments are emitted by highly excited compound nuclei formed in incomplete fusion reactions. 12 refs., 26 figs
El strength function at high spin and excitation energy
International Nuclear Information System (INIS)
Barrette, J.
1983-04-01
Recently giant dipole resonance-like concentration of the dipole strength function in nuclei was observed at both high excitation energies and high spins. This observation raises the possibility of obtaining new information on the shape of rapidly rotating heated nuclei. Recent experimental results on this subject are reviewed
Investigations of multiphoton excitation and ionization in a short range potential
International Nuclear Information System (INIS)
Susskind, S.M.; Cowley, S.C.; Valeo, E.J.
1989-02-01
We introduce an approach to the study of excitation and ionization for a system with a short range potential. In particular, analytical and numerical results are presented for the multiphoton ionization rate, under strong field conditions, of an electron confined by a δ-function potential. 9 refs., 3 figs
Investigations of multiphoton excitation and ionization in a short range potential
Energy Technology Data Exchange (ETDEWEB)
Susskind, S.M.; Cowley, S.C.; Valeo, E.J.
1989-02-01
We introduce an approach to the study of excitation and ionization for a system with a short range potential. In particular, analytical and numerical results are presented for the multiphoton ionization rate, under strong field conditions, of an electron confined by a delta-function potential. 9 refs., 3 figs.
Measurements of vibrational excitation of N2, CO, and NO by low energy proton impact
International Nuclear Information System (INIS)
Krutein, J.; Linder, F.
1979-01-01
Differential scattering experiments are reported for proton impact on N 2 , CO, and NO in the energy range E/sub lab/=30--80 eV. The measurements include the range of very small scattering angles around 0 0 as well as the rainbow region. The vibrationally resolved energy-loss spectra show a relatively low vibrational inelasticity for all three systems. Differential cross sections, transition probabilities, and the mean vibrational energy transfer are presented. Rotational excitation is indicated by the broadening of the energy-loss peaks which is most significant for H + --NO. The small-angle scattering data for vibrational excitation in CO show good agreement with the impact parameter theory using the known long-range interactions for this system
Mott transition: Low-energy excitations and superconductivity
International Nuclear Information System (INIS)
Ioffe, L.B.; Larkin, A.I.
1988-09-01
It is possible that metal-dielectric transition does not result in changes of magnetic or crystallographic symmetry. In this case a fermionic spectrum is not changed at the transition, but additional low-energy excitations appear which can be described as a gauge field that has the same symmetry as an electromagnetic one. In the case of a non half-filled band gapless scalar Bose excitations also appear. Due to the presence of additional gauge field the physical conductivity is determined by the lowest conductivity of the Fermi or Bose subsystems. (author). 11 refs
International Nuclear Information System (INIS)
Chamberlain, M.B.; Baun, W.L.
1975-01-01
Soft x-ray appearance potential spectra of the 3d and 4d levels of polycrystalline cerium metal are reported in this paper. Resonant x-ray emissions are observed when the electron-excitation energy sweeps through the ionization energies of the 3d and 4d levels. The resonant x rays excited at the 3d-level onsets are considerably more intense, and are excited at a lower electron-excitation energy than the 3d-series characteristic x rays. In the neighborhood of the 4d-electron thresholds, four line-like structures extend to approx.8 eV below the 4d-electron binding energies, while two broad and more intense structures occur above the 4d onsets, with the largest one reaching a peak intensity at 12 eV above the 4d thresholds. The resonant emissions apparently arise from the decay of threshold-excited states which are bound to the inner vacancy and have core configurations nd 9 4f 3 , (n=3,4). The exchange interaction between the three 4f electrons and the respective d-orbital vacancy spreads the 4d-threshold structures over a 20 eV range of excitation energies and the 3d-threshold structures over a much smaller range
Low-energy charge transfer excitations in NiO
International Nuclear Information System (INIS)
Sokolov, V I; Yermakov, A Ye; Uimin, M A; Gruzdev, N B; Pustovarov, V A; Churmanov, V N; Ivanov, V Yu; Sokolov, P S; Baranov, A N; Moskvin, A S
2012-01-01
Comparative analysis of photoluminescence (PL) and photoluminescence excitation (PLE) spectra of NiO poly- and nanocrystals in the spectral range 2-5.5 eV reveals two PLE bands peaked near 3.7 and 4.6 eV with a dramatic rise in the low-temperature PLE spectral weight of the 3.7 eV PLE band in the nanocrystalline NiO as compared with its polycrystalline counterpart. In frames of a cluster model approach we assign the 3.7 eV PLE band to the low-energy bulk-forbidden p-d (t 1g (π)-e g ) charge transfer (CT) transition which becomes the allowed one in the nanocrystalline state while the 4.6 eV PLE band is related to a bulk allowed d-d (e g -e g ) CT transition scarcely susceptible to the nanocrystallization. The PLE spectroscopy of the nanocrystalline materials appears to be a novel informative technique for inspection of different CT transitions.
Ab initio calculation of electron excitation energies in solids
International Nuclear Information System (INIS)
Louie, S.G.
1996-02-01
Progress in the first-principles calculation of electron excitation energies in solids is discussed. Quasiparticle energies are computed by expanding the electron self energy to first order in the screened Coulomb interaction in the so-called GW approximation. The method was applied to explain and predict spectroscopic properties of a variety of systems. Several illustrative applications to semiconductors, materials under pressure, chemisorption, and point defects in solids are presented. A recent reformulation of the method employing mixed- space functions and imaginary time techniques is also discussed
Rydberg energies using excited state density functional theory
International Nuclear Information System (INIS)
Cheng, C.-L.; Wu Qin; Van Voorhis, Troy
2008-01-01
We utilize excited state density functional theory (eDFT) to study Rydberg states in atoms. We show both analytically and numerically that semilocal functionals can give quite reasonable Rydberg energies from eDFT, even in cases where time dependent density functional theory (TDDFT) fails catastrophically. We trace these findings to the fact that in eDFT the Kohn-Sham potential for each state is computed using the appropriate excited state density. Unlike the ground state potential, which typically falls off exponentially, the sequence of excited state potentials has a component that falls off polynomially with distance, leading to a Rydberg-type series. We also address the rigorous basis of eDFT for these systems. Perdew and Levy have shown using the constrained search formalism that every stationary density corresponds, in principle, to an exact stationary state of the full many-body Hamiltonian. In the present context, this means that the excited state DFT solutions are rigorous as long as they deliver the minimum noninteracting kinetic energy for the given density. We use optimized effective potential techniques to show that, in some cases, the eDFT Rydberg solutions appear to deliver the minimum kinetic energy because the associated density is not pure state v-representable. We thus find that eDFT plays a complementary role to constrained DFT: The former works only if the excited state density is not the ground state of some potential while the latter applies only when the density is a ground state density.
International Nuclear Information System (INIS)
Erturk, A; Inman, D J
2009-01-01
Piezoelectric transduction has received great attention for vibration-to-electric energy conversion over the last five years. A typical piezoelectric energy harvester is a unimorph or a bimorph cantilever located on a vibrating host structure, to generate electrical energy from base excitations. Several authors have investigated modeling of cantilevered piezoelectric energy harvesters under base excitation. The existing mathematical modeling approaches range from elementary single-degree-of-freedom models to approximate distributed parameter solutions in the sense of Rayleigh–Ritz discretization as well as analytical solution attempts with certain simplifications. Recently, the authors have presented the closed-form analytical solution for a unimorph cantilever under base excitation based on the Euler–Bernoulli beam assumptions. In this paper, the analytical solution is applied to bimorph cantilever configurations with series and parallel connections of piezoceramic layers. The base excitation is assumed to be translation in the transverse direction with a superimposed small rotation. The closed-form steady state response expressions are obtained for harmonic excitations at arbitrary frequencies, which are then reduced to simple but accurate single-mode expressions for modal excitations. The electromechanical frequency response functions (FRFs) that relate the voltage output and vibration response to translational and rotational base accelerations are identified from the multi-mode and single-mode solutions. Experimental validation of the single-mode coupled voltage output and vibration response expressions is presented for a bimorph cantilever with a tip mass. It is observed that the closed-form single-mode FRFs obtained from the analytical solution can successfully predict the coupled system dynamics for a wide range of electrical load resistance. The performance of the bimorph device is analyzed extensively for the short circuit and open circuit resonance
Beck, Warren F; Bishop, Michael M; Roscioli, Jerome D; Ghosh, Soumen; Frank, Harry A
2015-04-15
A consideration of the excited state potential energy surfaces of carotenoids develops a new hypothesis for the nature of the conformational motions that follow optical preparation of the S2 (1(1)Bu(+)) state. After an initial displacement from the Franck-Condon geometry along bond length alternation coordinates, it is suggested that carotenoids pass over a transition-state barrier leading to twisted conformations. This hypothesis leads to assignments for several dark intermediate states encountered in femtosecond spectroscopic studies. The Sx state is assigned to the structure reached upon the onset of torsional motions near the transition state barrier that divides planar and twisted structures on the S2 state potential energy surface. The X state, detected recently in two-dimensional electronic spectra, corresponds to a twisted structure well past the barrier and approaching the S2 state torsional minimum. Lastly, the S(∗) state is assigned to a low lying S1 state structure with intramolecular charge transfer character (ICT) and a pyramidal conformation. It follows that the bent and twisted structures of carotenoids that are found in photosynthetic light-harvesting proteins yield excited-state structures that favor the development of an ICT character and optimized energy transfer yields to (bacterio)chlorophyll acceptors. Copyright © 2015 Elsevier Inc. All rights reserved.
Atomic excitation and molecular dissociation by low energy electron collisions
International Nuclear Information System (INIS)
Weyland, Marvin
2016-01-01
In this work, momentum imaging experiments have been conducted for the electron impact excitation of metastable states in noble gases and for dissociative electron attachment (DEA) in polyatomic molecules. For the electron impact excitation study a new experimental technique has been developed which is able to measure the scattering angle distribution of the electrons by detection of the momentum transfer to the atoms. Momentum transfer images have been recorded for helium and neon at fixed electron impact energy close to the excitation threshold and good agreement with current R-matrix theory calculations was found. A new momentum imaging apparatus for negative ions has been built for the purpose of studying DEA in biologically relevant molecules. During this work, DEA was investigated in the molecules ammonia, water, formic acid, furan, pyridine and in two chlorofluorocarbons. Furthermore, the change of DEA resonance energies when molecules form clusters compared to monomers was investigated in ammonia and formic acid. The experimental results of most studied molecules could be compared to recent theoretical calculations and they support further development in the theoretical description of DEA. The new apparatus built in this work also delivered a superior momentum resolution compared to existing setups. This allows the momentum imaging of heavier fragments and fragments with lower kinetic energy.
Atomic excitation and molecular dissociation by low energy electron collisions
Energy Technology Data Exchange (ETDEWEB)
Weyland, Marvin
2016-11-16
In this work, momentum imaging experiments have been conducted for the electron impact excitation of metastable states in noble gases and for dissociative electron attachment (DEA) in polyatomic molecules. For the electron impact excitation study a new experimental technique has been developed which is able to measure the scattering angle distribution of the electrons by detection of the momentum transfer to the atoms. Momentum transfer images have been recorded for helium and neon at fixed electron impact energy close to the excitation threshold and good agreement with current R-matrix theory calculations was found. A new momentum imaging apparatus for negative ions has been built for the purpose of studying DEA in biologically relevant molecules. During this work, DEA was investigated in the molecules ammonia, water, formic acid, furan, pyridine and in two chlorofluorocarbons. Furthermore, the change of DEA resonance energies when molecules form clusters compared to monomers was investigated in ammonia and formic acid. The experimental results of most studied molecules could be compared to recent theoretical calculations and they support further development in the theoretical description of DEA. The new apparatus built in this work also delivered a superior momentum resolution compared to existing setups. This allows the momentum imaging of heavier fragments and fragments with lower kinetic energy.
Excitation functions for 121,123Sb(α,xn), (x=1-4) reactions in approx. 10-40 MeV range
International Nuclear Information System (INIS)
Prasad, R.; Bhardwaj, H.D.
1986-04-01
Excitation functions for 121 Sb(α,n), 121 Sb(α,2n), 123 Sb(α,n) and 123 Sb(α,3n) reactions in the energy range approx. 10 to 40 MeV have been measured using stacked-foil technique and are calculated theoretically using statistical model with and without the inclusion of pre-equilibrium emission. Inclusion of pre-equilibrium emission is found to give good agreement between the experimental and measured excitation functions. (author)
Intermediate energy electron impact excitation of composite vibrational modes in phenol
Energy Technology Data Exchange (ETDEWEB)
Neves, R. F. C. [School of Chemical and Physical Sciences, Flinders University, G.P.O. Box 2100, Adelaide, SA 5001 (Australia); Instituto Federal do Sul de Minas Gerais, Campus Poços de Caldas, Minas Gerais (Brazil); Departamento de Física, Universidade Federal de Juiz de Fora, 36036-900, Juiz de Fora, Minas Gerais (Brazil); Jones, D. B. [School of Chemical and Physical Sciences, Flinders University, G.P.O. Box 2100, Adelaide, SA 5001 (Australia); Lopes, M. C. A.; Nixon, K. L. [Departamento de Física, Universidade Federal de Juiz de Fora, 36036-900, Juiz de Fora, Minas Gerais (Brazil); Oliveira, E. M. de; Lima, M. A. P. [Instituto de Física ‘Gleb Wataghin,’ Universidade Estadual de Campinas, 13083-859 Campinas, São Paulo (Brazil); Costa, R. F. da [Centro de Ciências Naturais e Humanas, Universidade Federal do ABC, 09210-580 Santo André, São Paulo (Brazil); Varella, M. T. do N. [Instituto de Física, Universidade de São Paulo, C.P. 66318, 05315-970 São Paulo (Brazil); Bettega, M. H. F. [Departamento de Física, Universidade Federal do Paraná, C.P. 19044, 81531-990 Curitiba, Paraná (Brazil); Silva, G. B. da [Universidade Federal de Mato Grosso, Barra do Garças, Mato Grosso (Brazil); Brunger, M. J., E-mail: Michael.Brunger@flinders.edu.au [School of Chemical and Physical Sciences, Flinders University, G.P.O. Box 2100, Adelaide, SA 5001 (Australia); Institute of Mathematical Sciences, University of Malaya, 50603 Kuala Lumpur (Malaysia)
2015-05-21
We report differential cross section results from an experimental investigation into the electron impact excitation of a number of the low-lying composite (unresolved) vibrational modes in phenol (C{sub 6}H{sub 5}OH). The measurements were carried out at incident electron energies in the range 15–40 eV and for scattered-electron angles in the range 10–90°. The energy resolution of those measurements was typically ∼80 meV. Calculations, using the GAMESS code, were also undertaken with a B3LYP/aug-cc-pVDZ level model chemistry, in order to enable us to assign vibrational modes to the features observed in our energy loss spectra. To the best of our knowledge, the present cross sections are the first to be reported for vibrational excitation of the C{sub 6}H{sub 5}OH molecule by electron impact.
Multireference excitation energies for bacteriochlorophylls A within light harvesting system 2
DEFF Research Database (Denmark)
Anda, Andre; Hansen, Thorsten; De Vico, Luca
2016-01-01
Light-harvesting system 2 (LH2) of purple bacteria is one of the most popular antenna complexes used to study Nature's way of collecting and channeling solar energy. The dynamics of the absorbed energy is probed by ultrafast spectroscopy. Simulation of these experiments relies on fitting a range...... bacteriochlorophylls in LH2. We find that the excitation energies vary among the bacteriochlorophyll monomers and that they are regulated by the curvature of the macrocycle ring and the dihedral angle of an acetyl moiety. Increasing the curvature lifts the ground state energy, which causes a red shift...
DEFF Research Database (Denmark)
Bohr, Henrik; Malik, F. Bary
2013-01-01
The observed multiple de-excitation pathways of photo-absorbed electronic excited state in the peridinin–chlorophyll complex, involving both energy and charge transfers among its constituents, are analyzed using the bio-Auger (B-A) theory. It is also shown that the usually used F¨orster–Dexter...
Coulomb excitation of 206Hg at relativistic energies
Alexander, Tom
The region of the nuclear chart surrounding the doubly-magic nucleus 208Pb provides a key area to constrain and develop contemporary nuclear structure models. One aspect of particular interest is the transition strength of the first excited 2+ state in even-even nuclei; this work describes the measurement of this value for the case of 206Hg, where the Z=80 line meets the N=126 shell closure. The nuclei of interest were synthesized using relativistic-energy projectile fragmentation at the GSI facility in Germany. They were produced in the fragmentation of a primary 208Pb beam at an energy of 1 GeV per nucleon, and separated and identifed using the Fragment Separator. The secondary beams with an energy of 140 MeV per nucleon were Coulomb excited on a secondary target of 400 mg/cm. 2 gold. Gamma-rays were detected with the Advanced GAmma Tracking Array (AGATA). The precise scattering angle for Doppler-correction was determined with position information from the Lund-York-Cologne-CAlorimeter(LYCCA). Using the sophisticated tracking algorithm native to AGATA in conjunction with pulse-shape analysis, a precise Doppler-correction is performed on the gamma spectra, and using a complex n-dimensional analysis, the B(E2) value for 206Hg is extracted relative to the known value also measured in 206Pb. A total of 409 million 206Hg particles were measured, and a cross-section of 50 mb was determined for the 2+ state at 1068 keV. The measurement of the B(E2) transition strength was found to be 1.109 W.u. This result is compared to a number of theoretical calculations, including two Gogny forces, and a modified shell model parametrization and is found to be smaller than all calculated estimations, implying that the first excited 2. + state in . {206}Hg is uncollective in nature.
Energy dependence of polymer gels in the orthovoltage energy range
Directory of Open Access Journals (Sweden)
Yvonne Roed
2014-03-01
Full Text Available Purpose: Ortho-voltage energies are often used for treatment of patients’ superficial lesions, and also for small- animal irradiations. Polymer-Gel dosimeters such as MAGAT (Methacrylic acid Gel and THPC are finding increasing use for 3-dimensional verification of radiation doses in a given treatment geometry. For mega-voltage beams, energy dependence of MAGAT has been quoted as nearly energy-independent. In the kilo-voltage range, there is hardly any literature to shade light on its energy dependence.Methods: MAGAT was used to measure depth-dose for 250 kVp beam. Comparison with ion-chamber data showed a discrepancy increasing significantly with depth. An over-response as much as 25% was observed at a depth of 6 cm.Results and Conclusion: Investigation concluded that 6 cm water in the beam resulted in a half-value-layer (HVL change from 1.05 to 1.32 mm Cu. This amounts to an effective-energy change from 81.3 to 89.5 keV. Response measurements of MAGAT at these two energies explained the observed discrepancy in depth-dose measurements. Dose-calibration curves of MAGAT for (i 250 kVp beam, and (ii 250 kVp beam through 6 cm of water column are presented showing significant energy dependence.-------------------Cite this article as: Roed Y, Tailor R, Pinksy L, Ibbott G. Energy dependence of polymer gels in the orthovoltage energy range. Int J Cancer Ther Oncol 2014; 2(2:020232. DOI: 10.14319/ijcto.0202.32
Excitation of higher lying energy states in a rubidium DPAL
Wallerstein, A. J.; Perram, Glen; Rice, Christopher A.
2018-02-01
The spontaneous emission in a cw rubidium diode dumped alkali laser (DPAL) system was analyzed. The fluorescence from higher lying states decreases with additional buffer gas. The intermediate states (7S, 6P, 5D) decay more slowly with buffer gas and scale super-linearly with alkali density. A detailed kinetic model has been constructed, where the dominant mechanisms are energy pooling and single photon ionization. It also includes pumping into the non-Lorentzian wings of absorption profiles, fine structure mixing, collisional de-excitation, and Penning ionization. Effects of ionization in a high powered CW rubidium DPAL were assessed.
Energy-Looping Nanoparticles: Harnessing Excited-State Absorption for Deep-Tissue Imaging.
Levy, Elizabeth S; Tajon, Cheryl A; Bischof, Thomas S; Iafrati, Jillian; Fernandez-Bravo, Angel; Garfield, David J; Chamanzar, Maysamreza; Maharbiz, Michel M; Sohal, Vikaas S; Schuck, P James; Cohen, Bruce E; Chan, Emory M
2016-09-27
Near infrared (NIR) microscopy enables noninvasive imaging in tissue, particularly in the NIR-II spectral range (1000-1400 nm) where attenuation due to tissue scattering and absorption is minimized. Lanthanide-doped upconverting nanocrystals are promising deep-tissue imaging probes due to their photostable emission in the visible and NIR, but these materials are not efficiently excited at NIR-II wavelengths due to the dearth of lanthanide ground-state absorption transitions in this window. Here, we develop a class of lanthanide-doped imaging probes that harness an energy-looping mechanism that facilitates excitation at NIR-II wavelengths, such as 1064 nm, that are resonant with excited-state absorption transitions but not ground-state absorption. Using computational methods and combinatorial screening, we have identified Tm(3+)-doped NaYF4 nanoparticles as efficient looping systems that emit at 800 nm under continuous-wave excitation at 1064 nm. Using this benign excitation with standard confocal microscopy, energy-looping nanoparticles (ELNPs) are imaged in cultured mammalian cells and through brain tissue without autofluorescence. The 1 mm imaging depths and 2 μm feature sizes are comparable to those demonstrated by state-of-the-art multiphoton techniques, illustrating that ELNPs are a promising class of NIR probes for high-fidelity visualization in cells and tissue.
Excitation energy partition in 74Ge + 165Ho collision at energy 8.5 MeV/A
International Nuclear Information System (INIS)
Blocki, J.; Grotowski, K.; Planeta, R.
1990-01-01
The distribution of the excitation energy between both fragments in Heavy Ion Collision has been measured recently for the reaction 74 Ge + 165 Ho at 8.5 MeV/A. One can see from the experimental data a gradual transition from moreless equal partition of the heat for the peripheral collisions (small energy loss) toward equal temperatures in more central collisions (high energy loss). The similar dependence of the heat partition as a function of the energy loss was observed earlier by Vandenbosch et al for the reaction 56 Fe + 238 U at 8.5 MeV/A and by Benton et al for the 56 Fe + 165 Ho for a broad range of energy dissipation. Theoretical calculations leading to the excitation energy division between both fragments have been carried out by Randrup and by Feldmeier. In both calculations the same excitation mechanism was assumed which is the exchange of particles between colliding nuclei. Differences between results are mainly due to the different shape parametrization and calculation of the potential energy. Randrup's results are moving much faster towards equal temperatures limit if one goes to more central collisions. Both models however do not predict the direction of the experimental mass flow for the 56 Fe + 165 Ho system. In the present paper classical dynamical calculations following Feldmeir's approach with some modifications are presented for 74 Ge + 165 Ho system
Raman active high energy excitations in URu{sub 2}Si{sub 2}
Energy Technology Data Exchange (ETDEWEB)
Buhot, Jonathan [Laboratoire Matériaux et Phénomènes Quantiques, UMR 7162 CNRS, Université Paris Diderot - Paris 7, Bât. Condorcet, 75205 Paris Cedex 13 (France); High Field Magnet Laboratory (HFML - EMFL), Institute for Molecules and Materials, Radboud University, Toernooiveld 7, 6525 ED Nijmegen (Netherlands); Gallais, Yann; Cazayous, Maximilien; Sacuto, Alain [Laboratoire Matériaux et Phénomènes Quantiques, UMR 7162 CNRS, Université Paris Diderot - Paris 7, Bât. Condorcet, 75205 Paris Cedex 13 (France); Piekarz, Przemysław [Institute of Nuclear Physics, Polish Academy of Sciences, 31-342 Krakòw (Poland); Lapertot, Gérard [Université Grenoble Alpes, INAC-SPSMS, F-38000 Grenoble (France); CEA, INAC-SPSMS, F-38000 Grenoble (France); Aoki, Dai [Université Grenoble Alpes, INAC-SPSMS, F-38000 Grenoble (France); CEA, INAC-SPSMS, F-38000 Grenoble (France); Institute for Materials Research, Tohoku University, Oarai, Ibaraki 311-1313 (Japan); Méasson, Marie-Aude, E-mail: marie-aude.measson@univ-paris-diderot.fr [Laboratoire Matériaux et Phénomènes Quantiques, UMR 7162 CNRS, Université Paris Diderot - Paris 7, Bât. Condorcet, 75205 Paris Cedex 13 (France)
2017-02-01
We have performed Raman scattering measurements on URu{sub 2}Si{sub 2} single crystals on a large energy range up to ∼1300 cm{sup −1} and in all the Raman active symmetries as a function of temperature down to 15 K. A large excitation, active only in the E{sub g} symmetry, is reported. It has been assigned to a crystal electric field excitation on the Uranium site. We discuss how this constrains the crystal electric field scheme of the Uranium ions. Furthermore, three excitations in the A{sub 1g} symmetry are observed. They have been associated to double Raman phonon processes consistently with ab initio calculations of the phonons dispersion.
Radiative proton capture to the first excited state of sup 29 P nucleus at subbarrier energies
Energy Technology Data Exchange (ETDEWEB)
Matulewicz, T; Dabrowska, M; Decowski, P; Kicinska-Habior, M; Sikora, B [Warsaw Univ. (Poland). Inst. Fizyki Doswiadczalnej; Toke, J [Rochester Univ., NY (USA). Nuclear Structure Research Lab.; Somorjai, E [Magyar Tudomanyos Akademia, Debrecen (Hungary). Atommag Kutato Intezete
1985-08-01
Differential cross sections at 0 deg and 90 deg measured for {sup 28}Si(p,{gamma}{sub 1}){sup 29}P reaction at proton energy range 2.3-2.9 MeV have been analyzed in terms of the direct-semidirect capture model extended by the effective potential approach. Spectroscopic factor of the first excited states of {sup 29}P nucleus was found to be 0.10+-0.05. 9 refs., 1 fig. (author).
International Nuclear Information System (INIS)
Duque, H. V.; Chiari, L.; Jones, D. B.; Pettifer, Z.; Silva, G. B. da; Limão-Vieira, P.; Blanco, F.; García, G.; White, R. D.; Lopes, M. C. A.; Brunger, M. J.
2014-01-01
Differential and integral cross section measurements, for incident electron energies in the 20–50 eV range, are reported for excitation of several composite vibrational modes in α-tetrahydrofurfuryl alcohol (THFA). Optimisation and frequency calculations, using GAUSSIAN 09 at the B3LYP/aug-cc-pVDZ level, were also undertaken for the two most abundant conformers of THFA, with results being reported for their respective mode classifications and excitation energies. Those calculations assisted us in the experimental assignments of the composite features observed in our measured energy loss spectra. There are, to the best of our knowledge, no other experimental or theoretical data currently available in the literature against which we can compare the present results
Energy Technology Data Exchange (ETDEWEB)
Duque, H. V. [School of Chemical and Physical Sciences, Flinders University, GPO Box 2100, Adelaide, SA 5001 (Australia); Departamento de Física, Universidade Federal de Juiz de Fora, Juiz de Fora, MG (Brazil); Chiari, L.; Jones, D. B.; Pettifer, Z. [School of Chemical and Physical Sciences, Flinders University, GPO Box 2100, Adelaide, SA 5001 (Australia); Silva, G. B. da [School of Chemical and Physical Sciences, Flinders University, GPO Box 2100, Adelaide, SA 5001 (Australia); Universidade Federal de Mato Grosso, Barra do Garças, Mato Grosso (Brazil); Limão-Vieira, P. [Laboratório de Colisões Atómicas e Moleculares, CEFITEC, Departamento de Física, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica (Portugal); Blanco, F. [Departamento de Física Atómica, Molecular y Nuclear, Universidad Complutense de Madrid, Madrid E-28040 (Spain); García, G. [Instituto de Física Fundamental, CSIC, Madrid E-28006 (Spain); White, R. D. [School of Engineering and Physical Sciences, James Cook University, Townsville, 4810 Queensland (Australia); Lopes, M. C. A. [Departamento de Física, Universidade Federal de Juiz de Fora, Juiz de Fora, MG (Brazil); Brunger, M. J., E-mail: Michael.Brunger@flinders.edu.au [School of Chemical and Physical Sciences, Flinders University, GPO Box 2100, Adelaide, SA 5001 (Australia); Institute of Mathematical Sciences, University of Malaya, Kuala Lumpur (Malaysia)
2014-06-07
Differential and integral cross section measurements, for incident electron energies in the 20–50 eV range, are reported for excitation of several composite vibrational modes in α-tetrahydrofurfuryl alcohol (THFA). Optimisation and frequency calculations, using GAUSSIAN 09 at the B3LYP/aug-cc-pVDZ level, were also undertaken for the two most abundant conformers of THFA, with results being reported for their respective mode classifications and excitation energies. Those calculations assisted us in the experimental assignments of the composite features observed in our measured energy loss spectra. There are, to the best of our knowledge, no other experimental or theoretical data currently available in the literature against which we can compare the present results.
Self-energy correction to the hyperfine splitting for excited states
International Nuclear Information System (INIS)
Wundt, B. J.; Jentschura, U. D.
2011-01-01
The self-energy corrections to the hyperfine splitting is evaluated for higher excited states in hydrogenlike ions using an expansion in the binding parameter Zα, where Z is the nuclear-charge number and α is the fine-structure constant. We present analytic results for D, F, and G states, and for a number of highly excited Rydberg states, with principal quantum numbers in the range 13≤n≤16, and orbital angular momenta l=n-2 and l=n-1. A closed-form analytic expression is derived for the contribution of high-energy photons, valid for any state with l≥2 and arbitrary n, l, and total angular momentum j. The low-energy contributions are written in the form of generalized Bethe logarithms and evaluated for selected states.
International Nuclear Information System (INIS)
Agarwal, Avinash; Rizvi, I.A.; Gupta, Meenal; Ahamad, Tauseef; Ghugre, S.S.; Sinha, A.K.; Chaubey, A.K.
2008-01-01
With the motivation of studying the complete and incomplete fusion reactions, excitation functions for the reactions 93 Nb(Ne, p2n) 110 Sn, 93 Nb(Ne, 2pn) 110 In, 93 Nb(Ne, 2p2n) 109 In, 93 Nb(Ne, αn) 108 In, 93 Nb(Neα2n) 107 In and 93 Nb(Ne, α p n) 107 Cd have been measured at the incident energy ranging from 91.4 MeV - 145 MeV. The well established activation technique followed by off line high purity gamma- ray spectroscopy was employed. The measured excitation functions were compared with the statistical model calculations by using the codes ALICE-91 and Pace-4. The effect of variation of different parameters including level density parameter involved in these codes has also been studied. Excellent agreement was found between theoretical and experimental values in some of the fusion evaporation reaction channels. However, significant enhancement of cross-section observed in α-emission channels may be due to incomplete fusion process. (author)
Hashimoto, Yusuke; Bossini, Davide; Johansen, Tom H.; Saitoh, Eiji; Kirilyuk, Andrei; Rasing, Theo
2017-01-01
Using spin-wave tomography (SWaT), we have investigated the excitation and the propagation dynamics of optically-excited magnetoelastic waves, i.e. hybridized modes of spin waves and elastic waves, in a garnet film. By using time-resolved SWaT, we reveal the excitation dynamics of magnetoelastic waves through coherent-energy transfer between optically-excited pure-elastic waves and spin waves via magnetoelastic coupling. This process realizes frequency and wavenumber selective excitation of s...
Spectroscopic properties of the S1 state of linear carotenoids after excess energy excitation
Kuznetsova, Valentyna; Southall, June; Cogdell, Richard J.; Fuciman, Marcel; Polívka, Tomáš
2017-09-01
Properties of the S1 state of neurosporene, spheroidene and lycopene were studied after excess energy excitation in the S2 state. Excitation of carotenoids into higher vibronic levels of the S2 state generates excess vibrational energy in the S1 state. The vibrationally hot S1 state relaxes faster when carotenoid is excited into the S2 state with excess energy, but the S1 lifetime remains constant regardless of which vibronic level of the S2 state is excited. The S∗ signal depends on excitation energy only for spheroidene, which is likely due to asymmetry of the molecule, facilitating conformations responsible for the S∗ signal.
A simplified approach for the coupling of excitation energy transfer
Energy Technology Data Exchange (ETDEWEB)
Shi Bo [Hefei National Laboratory for Physical Science at Microscale, University of Science and Technology of China, Hefei 230026 (China); Department of Chemical Physics, University of Science and Technology of China, Hefei 230026 (China); Gao Fang, E-mail: gaofang@iim.ac.cn [Institute of Intelligent Machines, Chinese Academy of Sciences, Hefei 230031 (China); State Key Laboratory of Robotics, Shenyang Institute of Automation, Chinese Academy of Sciences, Shenyang 110016 (China); Liang Wanzhen [Hefei National Laboratory for Physical Science at Microscale, University of Science and Technology of China, Hefei 230026 (China); Department of Chemical Physics, University of Science and Technology of China, Hefei 230026 (China)
2012-02-06
Highlights: Black-Right-Pointing-Pointer We propose a simple method to calculate the coupling of singlet-to-singlet and triplet-to-triplet energy transfer. Black-Right-Pointing-Pointer Coulomb term are the major contribution to the coupling of singlet-to-singlet energy transfer. Black-Right-Pointing-Pointer Effect from the intermolecular charge-transfer states dorminates in triplet-to-triplet energy transfer. Black-Right-Pointing-Pointer This method can be expanded by including correlated wavefunctions. - Abstract: A simplified approach for computing the electronic coupling of nonradiative excitation-energy transfer is proposed by following Scholes et al.'s construction on the initial and final states [G.D. Scholes, R.D. Harcourt, K.P. Ghiggino, J. Chem. Phys. 102 (1995) 9574]. The simplification is realized through defining a set of orthogonalized localized MOs, which include the polarization effect of the charge densities. The method allows calculating the coupling of both the singlet-to-singlet and triplet-to-triplet energy transfer. Numerical tests are performed for a few of dimers with different intermolecular orientations, and the results demonstrate that Coulomb term are the major contribution to the coupling of singlet-to-singlet energy transfer whereas in the case of triplet-to-triplet energy transfer, the dominant effect is arisen from the intermolecular charge-transfer states. The present application is on the Hartree-Fock level. However, the correlated wavefunctions which are normally expanded in terms of the determinant wavefunctions can be employed in the similar way.
Plunger lifetime measurements after Coulomb excitation at intermediate beam energies
Energy Technology Data Exchange (ETDEWEB)
Hackstein, Matthias; Dewald, Alfred; Fransen, Christoph; Ilie, Gabriela; Jolie, Jan; Melon, Barbara; Pissulla, Thomas; Rother, Wolfram; Zell, Karl-Oskar [University of Cologne (Germany); Petkov, Pavel [University of Cologne (Germany); INRNE (Bulgaria); Chester, Aaron; Adrich, Przemyslaw; Bazin, Daniel; Bowen, Matt; Gade, Alexandra; Glasmacher, Thomas; Miller, Dave; Moeller, Victoria; Starosta, Krzysztof; Stolz, Andreas; Vaman, Constantin; Voss, Philip; Weissharr, Dirk [Michigan State Univerity (United States); Moeller, Oliver [TU Darmstadt (Germany)
2008-07-01
Two recoil-distance-doppler-shift (RDDS) experiments were performed at the NSCL/MSU using Coulomb excitations of the projectile nuclei {sup 110}Pd, {sup 114}Pd at beam energies of 54 MeV/u in order to investigate the evolution of deformation of neutron rich paladium isotopes. The experimental set-up consisted of a dedicated plunger device, developed at the University of Cologne, the SEGA Ge-array and the S800 spectrometer. Lifetimes of the 2{sub 1}{sup +}-states in {sup 110}Pd and {sup 114}Pd were derived from the analysis of the {gamma}-line-shapes as well as from the measured decay-curves. Special features of the data analysis, e.g. features originating from the very high recoil velocities, are discussed.
Collective and single-particle states at high excitation energy
International Nuclear Information System (INIS)
Van den Berg, A.M.; Van der Molen, H.K.T.; Harakeh, M.N.; Akimune, H.; Daito, I.; Fujimura, H.; Fujiwara, M.; Ihara, F.; Inomata, T.
2000-01-01
Complete text of publication follows. Damping of high-lying single-particle states was investigated by the study of proton decay from high-lying states in 91 Nb, populated by the 90 Zr(α,t) reaction with E α = 180 MeV. In addition to decay to the ground state of 90 Zr, semi-direct decay was observed to the low-lying (2 + and 3 - ) phonon states, confirming the conclusion from other experiments that these phonon states play an important role in the damping process of the single-particle states. Furthermore, the population and decay of Isobaric Analogue States of 91 Zr, which are located at an excitation energy of about 10 - 12 MeV in 91 Nb, has been studied in the same reaction. (author)
Smirnov, Yu M.
2018-03-01
Electron-impact excitation of lead atom levels belonging to 6pnd configurations has been studied in experiment. One hundred two excitation cross-sections have been measured at an incident electron energy of 50 eV. Eleven optical excitation functions (OEFs) have been recorded in the exciting electron energy range of E = 0-200 eV. The resulting findings were used to study the excitation cross-sections dependence on the principal quantum number of upper levels for thirteen PbI spectral series.
Complex fragments from excited actinide nuclei. A new test of the finite range model
International Nuclear Information System (INIS)
Sarantities, D.G.; Bowman, D.R.; Wozniak, G.J.; Charity, R.J.; Liu, Z.H.; McDonald, R.J.; McMahan, M.A.; Moretto, L.G.
1989-01-01
Complex fragments ranging in charge from 7 ≤ Z ≤ 45 have been detected in binary coincidence following the reaction of 8.4 MeV/u 232 Th+ 12 C, and are shown to arise from the binary decay of a 244 Cm compound nucleus. This work confirms earlier radiochemical observations of very light fragments in the fission fragment mass distribution, establishes their binary character, and interprets their yield in terms of finite range potential energy barriers. (orig.)
Complex fragments from excited actinide nuclei: A new test of the finite range model
International Nuclear Information System (INIS)
Sarantities, D.G.; Bowman, D.R.; Wozniak, G.J.; Charity, R.J.; Liu, Z.H.; McDonald, R.J.; McMahan, M.A.; Moretto, L.G.
1988-05-01
Complex fragments ranging in charge from 7≤Z≤45 have been detected in binary coincidence following the reaction of 8.4 MeV/u 232 Th+ 12 C, and are shown to arise from the binary decay of a 244 Cm compound nucleus. This work confirms earlier radiochemical observations of very light fragments in the fission fragment mass distribution, establishes their binary character, and interprets their yield in terms of finite range potential energy barriers. 15 refs., 3 figs
International Nuclear Information System (INIS)
Gerard, I.
1993-01-01
A characterization tool using synchrotron radiation as a light source to record excitation spectra of the visible luminescence of phosphors induced by photons in the V UV and UV range, at several temperatures (10 to 300 K), is developed. The absorption and deexcitation mechanisms in Y F 3 , La F 3 and Th F 4 matrices doped with Eu 3+ , Tb 3+ , Dy 3+ and Er 3+ ions and polluted with oxygen ions, are examined; charge transfer bands appear clearly. The 4 f n to 4 f n-1 5 d transition bands are also observed on the excitation spectra of the visible luminescence of these compounds and two processes are proposed to interpret the energy relaxation. In order to determine the candidates for the color plasma display panel, measurements of luminous and external quantum yields for efficient phosphors are carried out. The Y F 3 :Eu 3+ compound is shown as a good candidate for the red emission in color plasma display panels
International Nuclear Information System (INIS)
Kuen, I.; Howorka, F.
1983-01-01
Absolute cross sections for the excitation of optically emitting states in collisions of He + , Ne + , Ar + , Kr + , B + , He ++ , Ne ++ and Ar ++ with oxygen molecules are measured, the energy range of the ion being1 - 1800 eV Lab for the singly charged and 1 - 3600 eV for the doubly charged ions. Seven important processes can be distinguished: charge exchange excitation of O 2 + band, O I, O II, X I and X II lines (X + , X ++ being the primary ion), direct excitation of X II and double charge exchange excitations. The energy dependences of the excitation cross sections are remarkably different for different processes but similar for one process with different ions. The sum total of all cross sections together for excitations which lead to light emission is on the order of a few square angstroms at 1000 eV c.m. energy. The results are of interest for surface investigations, plasma diagnostics and laser work. (Author)
Energy harvesting from human motion: exploiting swing and shock excitations
International Nuclear Information System (INIS)
Ylli, K; Hoffmann, D; Willmann, A; Becker, P; Folkmer, B; Manoli, Y
2015-01-01
Modern compact and low power sensors and systems are leading towards increasingly integrated wearable systems. One key bottleneck of this technology is the power supply. The use of energy harvesting techniques offers a way of supplying sensor systems without the need for batteries and maintenance. In this work we present the development and characterization of two inductive energy harvesters which exploit different characteristics of the human gait. A multi-coil topology harvester is presented which uses the swing motion of the foot. The second device is a shock-type harvester which is excited into resonance upon heel strike. Both devices were modeled and designed with the key constraint of device height in mind, in order to facilitate the integration into the shoe sole. The devices were characterized under different motion speeds and with two test subjects on a treadmill. An average power output of up to 0.84 mW is achieved with the swing harvester. With a total device volume including the housing of 21 cm 3 a power density of 40 μW cm −3 results. The shock harvester generates an average power output of up to 4.13 mW. The power density amounts to 86 μW cm −3 for the total device volume of 48 cm 3 . Difficulties and potential improvements are discussed briefly. (paper)
Kowalski, Karol
2009-05-21
In this article we discuss the problem of proper balancing of the noniterative corrections to the ground- and excited-state energies obtained with approximate coupled cluster (CC) and equation-of-motion CC (EOMCC) approaches. It is demonstrated that for a class of excited states dominated by single excitations and for states with medium doubly excited component, the newly introduced nested variant of the method of moments of CC equations provides mathematically rigorous way of balancing the ground- and excited-state correlation effects. The resulting noniterative methodology accounting for the effect of triples is tested using its parallel implementation on the systems, for which iterative CC/EOMCC calculations with full inclusion of triply excited configurations or their most important subset are numerically feasible.
Intermediate energy cross sections for electron-impact vibrational-excitation of pyrimidine
Energy Technology Data Exchange (ETDEWEB)
Jones, D. B. [School of Chemical and Physical Sciences, Flinders University, GPO Box 2100, Adelaide, SA 5001 (Australia); Ellis-Gibbings, L.; García, G. [Instituto de Física Fundamental, CSIC, Serrano 113-bis, 28006 Madrid (Spain); Nixon, K. L. [Departamento de Física, Universidade Federal de Juiz de Fora, 36036-330 Juiz de Fora, Minas Gerais (Brazil); School of Biology, Chemistry and Forensic Science, University of Wolverhampton, Wolverhampton WV1 1LY (United Kingdom); Lopes, M. C. A. [Departamento de Física, Universidade Federal de Juiz de Fora, 36036-330 Juiz de Fora, Minas Gerais (Brazil); Brunger, M. J., E-mail: Michael.Brunger@flinders.edu.au [School of Chemical and Physical Sciences, Flinders University, GPO Box 2100, Adelaide, SA 5001 (Australia); Institute of Mathematical Sciences, University of Malaya, 50603 Kuala Lumpur (Malaysia)
2015-09-07
We report differential cross sections (DCSs) and integral cross sections (ICSs) for electron-impact vibrational-excitation of pyrimidine, at incident electron energies in the range 15–50 eV. The scattered electron angular range for the DCS measurements was 15°–90°. The measurements at the DCS-level are the first to be reported for vibrational-excitation in pyrimidine via electron impact, while for the ICS we extend the results from the only previous condensed-phase study [P. L. Levesque, M. Michaud, and L. Sanche, J. Chem. Phys. 122, 094701 (2005)], for electron energies ⩽12 eV, to higher energies. Interestingly, the trend in the magnitude of the lower energy condensed-phase ICSs is much smaller when compared to the corresponding gas phase results. As there is no evidence for the existence of any shape-resonances, in the available pyrimidine total cross sections [Baek et al., Phys. Rev. A 88, 032702 (2013); Fuss et al., ibid. 88, 042702 (2013)], between 10 and 20 eV, this mismatch in absolute magnitude between the condensed-phase and gas-phase ICSs might be indicative for collective-behaviour effects in the condensed-phase results.
Trautmann, N.; Hauke, P.
2018-02-01
The transport of excitations governs fundamental properties of matter. Particularly rich physics emerges in the interplay between disorder and environmental noise, even in small systems such as photosynthetic biomolecules. Counterintuitively, noise can enhance coherent quantum transport, which has been proposed as a mechanism behind the high transport efficiencies observed in photosynthetic complexes. This effect has been called "environment-assisted quantum transport". Here, we propose a quantum simulation of the excitation transport in an open quantum network, taking advantage of the high controllability of current trapped-ion experiments. Our scheme allows for the controlled study of various different aspects of the excitation transfer, ranging from the influence of static disorder and interaction range, over the effect of Markovian and non-Markovian dephasing, to the impact of a continuous insertion of excitations. Our paper discusses experimental error sources and realistic parameters, showing that it can be implemented in state-of-the-art ion-chain experiments.
Excitation and charge transfer in low-energy hydrogen atom collisions with neutral oxygen
Barklem, P. S.
2018-02-01
Excitation and charge transfer in low-energy O+H collisions is studied; it is a problem of importance for modelling stellar spectra and obtaining accurate oxygen abundances in late-type stars including the Sun. The collisions have been studied theoretically using a previously presented method based on an asymptotic two-electron linear combination of atomic orbitals (LCAO) model of ionic-covalent interactions in the neutral atom-hydrogen-atom system, together with the multichannel Landau-Zener model. The method has been extended to include configurations involving excited states of hydrogen using an estimate for the two-electron transition coupling, but this extension was found to not lead to any remarkably high rates. Rate coefficients are calculated for temperatures in the range 1000-20 000 K, and charge transfer and (de)excitation processes involving the first excited S-states, 4s.5So and 4s.3So, are found to have the highest rates. Data are 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/vizbin/qcat?J/A+A/610/A57. The data are also available at http://https://github.com/barklem/public-data
Excitation and charge transfer in low-energy hydrogen atom collisions with neutral iron
Barklem, P. S.
2018-05-01
Data for inelastic processes due to hydrogen atom collisions with iron are needed for accurate modelling of the iron spectrum in late-type stars. Excitation and charge transfer in low-energy Fe+H collisions is studied theoretically using a previously presented method based on an asymptotic two-electron linear combination of atomic orbitals model of ionic-covalent interactions in the neutral atom-hydrogen-atom system, together with the multi-channel Landau-Zener model. An extensive calculation including 166 covalent states and 25 ionic states is presented and rate coefficients are calculated for temperatures in the range 1000-20 000 K. The largest rates are found for charge transfer processes to and from two clusters of states around 6.3 and 6.6 eV excitation, corresponding in both cases to active 4d and 5p electrons undergoing transfer. Excitation and de-excitation processes among these two sets of states are also significant. Full Tables and rate coefficient data are only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/612/A90
International Nuclear Information System (INIS)
Boneva, S.T.; Khitrov, V.A.; Sukhovoj, A.M.; Vojnov, A.V.
1990-01-01
Intensities of two-quanta cascades are obtained for 2-3 final low-lying levels of the following nuclei 146 Nd, 174 Yb and 183 W. These measured intensities are compared with the intensities calculated in the frame of various models at primary transition energies ranging from 0.5 MeV to the neutron binding energy. Some excitation energy intervals are revealed, experimentally obtained intensities of cascade are inconsistent with model calculations. 15 refs.; 7 figs
Excitation of vibrational quanta in furfural by intermediate-energy electrons
Jones, D. B.; Neves, R. F. C.; Lopes, M. C. A.; da Costa, R. F.; Varella, M. T. do N.; Bettega, M. H. F.; Lima, M. A. P.; García, G.; Blanco, F.; Brunger, M. J.
2015-12-01
We report cross sections for electron-impact excitation of vibrational quanta in furfural, at intermediate incident electron energies (20, 30, and 40 eV). The present differential cross sections are measured over the scattered electron angular range 10°-90°, with corresponding integral cross sections subsequently being determined. Furfural is a viable plant-derived alternative to petrochemicals, being produced via low-temperature plasma treatment of biomass. Current yields, however, need to be significantly improved, possibly through modelling, with the present cross sections being an important component of such simulations. To the best of our knowledge, there are no other cross sections for vibrational excitation of furfural available in the literature, so the present data are valuable for this important molecule.
Excitation of vibrational quanta in furfural by intermediate-energy electrons
Energy Technology Data Exchange (ETDEWEB)
Jones, D. B. [School of Chemical and Physical Sciences, Flinders University, GPO Box 2100, Adelaide, South Australia 5001 (Australia); Neves, R. F. C. [School of Chemical and Physical Sciences, Flinders University, GPO Box 2100, Adelaide, South Australia 5001 (Australia); Instituto Federal do Sul de Minas Gerais, Campus Poços de Caldas, Minas Gerais (Brazil); Departamento de Física, Universidade Federal de Juiz de Fora, 36036-900, Juiz de Fora, MG (Brazil); Lopes, M. C. A. [Departamento de Física, Universidade Federal de Juiz de Fora, 36036-900, Juiz de Fora, MG (Brazil); Costa, R. F. da [Instituto de Física “Gleb Wataghin,” Universidade Estadual de Campinas, Campinas, 13083-859 São Paulo (Brazil); Centro de Ciências Naturais e Humanas, Universidade Federal do ABC, Santo André, 09210-580 São Paulo (Brazil); Varella, M. T. do N. [Instituto de Física, Universidade de São Paulo, CP 66318, 05315-970 São Paulo, São Paulo (Brazil); Bettega, M. H. F. [Departamento de Física, Universidade Federal do Paraná, CP 19044, 81531-990 Curitiba, Paraná (Brazil); Lima, M. A. P. [Instituto de Física “Gleb Wataghin,” Universidade Estadual de Campinas, Campinas, 13083-859 São Paulo (Brazil); García, G. [Instituto de Física Fundamental, CSIC, Serrano 113-bis, 28006 Madrid (Spain); and others
2015-12-14
We report cross sections for electron-impact excitation of vibrational quanta in furfural, at intermediate incident electron energies (20, 30, and 40 eV). The present differential cross sections are measured over the scattered electron angular range 10°–90°, with corresponding integral cross sections subsequently being determined. Furfural is a viable plant-derived alternative to petrochemicals, being produced via low-temperature plasma treatment of biomass. Current yields, however, need to be significantly improved, possibly through modelling, with the present cross sections being an important component of such simulations. To the best of our knowledge, there are no other cross sections for vibrational excitation of furfural available in the literature, so the present data are valuable for this important molecule.
Excitation of vibrational quanta in furfural by intermediate-energy electrons
International Nuclear Information System (INIS)
Jones, D. B.; Neves, R. F. C.; Lopes, M. C. A.; Costa, R. F. da; Varella, M. T. do N.; Bettega, M. H. F.; Lima, M. A. P.; García, G.
2015-01-01
We report cross sections for electron-impact excitation of vibrational quanta in furfural, at intermediate incident electron energies (20, 30, and 40 eV). The present differential cross sections are measured over the scattered electron angular range 10°–90°, with corresponding integral cross sections subsequently being determined. Furfural is a viable plant-derived alternative to petrochemicals, being produced via low-temperature plasma treatment of biomass. Current yields, however, need to be significantly improved, possibly through modelling, with the present cross sections being an important component of such simulations. To the best of our knowledge, there are no other cross sections for vibrational excitation of furfural available in the literature, so the present data are valuable for this important molecule
Long-range interactions between excited helium and alkali-metal atoms
Zhang, J.-Y.
2012-12-03
The dispersion coefficients for the long-range interaction of the first four excited states of He, i.e., He(2 1,3S) and He(2 1,3P), with the low-lying states of the alkali-metal atoms Li, Na, K, and Rb are calculated by summing over the reduced matrix elements of the multipole transition operators. For the interaction between He and Li the uncertainty of the calculations is 0.1–0.5%. For interactions with other alkali-metal atoms the uncertainty is 1–3% in the coefficient C5, 1–5% in the coefficient C6, and 1–10% in the coefficients C8 and C10. The dispersion coefficients Cn for the interaction of He(2 1,3S) and He(2 1,3P) with the ground-state alkali-metal atoms and for the interaction of He(2 1,3S) with the alkali-metal atoms in their first 2P states are presented in this Brief Report. The coefficients for other pairs of atomic states are listed in the Supplemental Material.
Vibrational energy transfer in selectively excited diatomic molecules
International Nuclear Information System (INIS)
Dasch, C.J.
1978-09-01
Single rovibrational states of HCl(v=2), HBr(v=2), DCl(v=2), and CO(v=2) were excited with a pulsed optical parametric oscillator (OPO). Total vibrational relaxation rates near - resonance quenchers were measured at 295 0 K using time resolved infrared fluorescence. These rates are attributed primarily to V - V energy transfer, and they generally conform to a simple energy gap law. A small deviation was found for the CO(v) + DCl(v') relaxation rates. Upper limits for the self relaxation by V - R,T of HCl(v=2) and HBr(v=2) and for the two quantum exchange between HCl and HBr were determined. The HF dimer was detected at 295 0 K and 30 torr HF pressure with an optoacoustic spectrometer using the OPO. Pulsed and chopped, resonant and non-resonant spectrophones are analyzed in detail. From experiments and first order perturbation theory, these V - V exchange rates appear to behave as a first order perturbation in the vibrational coordinates. The rotational dynamics are known to be complicated however, and the coupled rotational - vibrational dynamics were investigated theoreticaly in infinite order by the Dillon and Stephenson and the first Magnus approximations. Large ΔJ transitions appear to be important, but these calculations differ by orders of magnitude on specific rovibrational transition rates. Integration of the time dependent semiclassical equations by a modified Gordon method and a rotationally distorted wave approximation are discussed as methods which would treat the rotational motion more accurately. 225 references
International Nuclear Information System (INIS)
LaBrecque, J.J.; Rosales, P.A.
1989-01-01
The relative sensitivities of low-medium and high-Z elements from manganese to lead were investigated via their K α employing 75 μCi of 32 P. This was accomplished by preparing various synthetic mixtures of elements in the range 25 ≤Z≤82, then simply introducing 32 P solution to form source-samples. The advantages of excitation with 32 P, a pure β-emitter with a β max. energy at 1709 keV, include the following: excitation of all the K α x-rays from manganese to lead; the relative sensitivities of the K x-rays are all within one order of magnitude; the source itself does not produce any spectral lines; and the background can be greatly reduced by filtering. Excitation with 32 P is compared with that of a conventional 109 Cd source and some possible applications are discussed. (author)
International Nuclear Information System (INIS)
Dorner, B.
1996-01-01
A short introduction to instrumental resolution is followed by a discussion of visibilities of phonon modes due to their eigenvectors. High precision phonon dispersion curves in GaAs are presented together with 'ab initio' calculations. Al 2 O 3 is taken as an example of selected visibility due to group theory. By careful determination of phonon intensities eigenvectors can be determined, such as in Silicon and Diamond. The investigation of magnon modes is shown for the garnet Fe 2 Ca 3 (GeO 4 ) 3 , where also a quantum gap due to zero point spin fluctuations was observed. The study of the splitting of excitons in CsFeCl 3 in an applied magnetic field demonstrates the possibilities of neutron polarisation analysis, which made it possible to observe a mode crossing. An outlook to inelastic X-ray scattering with very high energy resolution of synchrotron radiation is given with the examples of phonons in Beryllium and in water. (author) 19 figs., 36 refs
Excitation energy partition in deeply inelastic collisions between 40Ar and Ag at 27 MeV per nucleon
International Nuclear Information System (INIS)
Borderie, B.; Rivet, M.F.; Cabot, C.; Fuchs, H.; Gardes, D.; Hanappe, F.; Jouan, D.; Montoya, M.
1991-01-01
The dynamics of the two partners produced in dissipative collisions has been experimentally studied for the system 40 Ar+Ag at 27 MeV per nucleon. Primary masses of the fragments can then be calculated; the excitation energy partition between the two fragments is derived from the number of particles evaporated by each fragment. We found that this division evolves from equipartition to a repartition close to thermal equilibrium in the excitation energy range 300-350 MeV or interaction times 5-10x10 -22 s. (orig.)
Z-dependence of Mean Excitation Energies for Second and Third Row Atoms and Their Ions
DEFF Research Database (Denmark)
Sauer, Stephan P. A.; Sabin, John R.; Oddershede, Jens
2018-01-01
All mean excitations energies for second and third row atoms and their ions are calculated in the random‐phase approximation using large basis sets. To a very good approximation it turns out that mean excitation energies within an isoelectronic series is a quadratic function of the nuclear charge...
Excitation energy of a helium 3 quasiparticle in the bulk mixture at constant pressure
International Nuclear Information System (INIS)
Yim, M.B.
1981-01-01
A 3 He quasiparticle excitation energy in bulk mixture at zero pressure and 6% solution is calculated to O(x) using the bulk effective interaction of Yim and Massey. The present 3 He quasiparticle excitation energy is in agreement with the experimental result of Hilton, Scherm and Stirling. (author)
Exploring the vibrational fingerprint of the electronic excitation energy via molecular dynamics
International Nuclear Information System (INIS)
Deyne, Andy Van Yperen-De; Pauwels, Ewald; Ghysels, An; Waroquier, Michel; Van Speybroeck, Veronique; Hemelsoet, Karen; De Meyer, Thierry; De Clerck, Karen
2014-01-01
A Fourier-based method is presented to relate changes of the molecular structure during a molecular dynamics simulation with fluctuations in the electronic excitation energy. The method implies sampling of the ground state potential energy surface. Subsequently, the power spectrum of the velocities is compared with the power spectrum of the excitation energy computed using time-dependent density functional theory. Peaks in both spectra are compared, and motions exhibiting a linear or quadratic behavior can be distinguished. The quadratically active motions are mainly responsible for the changes in the excitation energy and hence cause shifts between the dynamic and static values of the spectral property. Moreover, information about the potential energy surface of various excited states can be obtained. The procedure is illustrated with three case studies. The first electronic excitation is explored in detail and dominant vibrational motions responsible for changes in the excitation energy are identified for ethylene, biphenyl, and hexamethylbenzene. The proposed method is also extended to other low-energy excitations. Finally, the vibrational fingerprint of the excitation energy of a more complex molecule, in particular the azo dye ethyl orange in a water environment, is analyzed
International Nuclear Information System (INIS)
Ayyad, Y.; Benlliure, J.; Casajeros, E.; Alvarez Pol, H.; Paradela, C.; Perez-Loureido, D.; Tarrio, D.; Bacquias, A.; Boudard, A.; Kezzar, K.; Leray, S.; Enqvist, T.; Foehr, V.; Kelic, A.; Pleskac, R.
2010-01-01
In this work we have investigated the total fission cross section of 181 Ta + 1 H at FRS (Fragment Separator - GSI) at 1, 0.8, 0.5 and 0.3 GeV with a specific setup, providing high accuracy measurements of the cross section values. the comparison of our data with previous results reveals a good agreement at high energies. However the situation remains unclear at lower energies. In general, our results covering a wide range of energy, are smoother. We have also compared the results obtained in this experiment, with several calculations performed with the intra-nuclear cascade model (INCL v4.1) coupled to de-excitation code (ABLAv3p), according to two different models describing fission process at high-excitation energies: statistical model of Bohr and Wheeler and the dynamical description of the fission process. We have showed that a simple statistical description largely over-predict the measured cross-section. Only a dynamical description of the fission, involving the role of the viscosity of the nuclear matter, provides a realistic result.
Directory of Open Access Journals (Sweden)
N. Davari
2014-03-01
Full Text Available The molecular ionization potential has a relatively strong electric-field dependence as compared to the excitation energies which has implications for electrical insulation since the excited states work as an energy sink emitting light in the UV/VIS region. At some threshold field, all the excited states of the molecule have vanished and the molecule is a two-state system with the ground state and the ionized state, which has been hypothesized as a possible origin of different streamer propagation modes. Constrained density-functional theory is used to calculate the field-dependent ionization potential of different types of molecules relevant for electrically insulating liquids. The low singlet-singlet excitation energies of each molecule have also been calculated using time-dependent density functional theory. It is shown that low-energy singlet-singlet excitation of the type n → π* (lone pair to unoccupied π* orbital has the ability to survive at higher fields. This type of excitation can for example be found in esters, diketones and many color dyes. For alkanes (as for example n-tridecane and cyclohexane on the other hand, all the excited states, in particular the σ → σ* excitations vanish in electric fields higher than 10 MV/cm. Further implications for the design of electrically insulating dielectric liquids based on the molecular ionization potential and excitation energies are discussed.
Heßelmann, Andreas
2015-04-14
Molecular excitation energies have been calculated with time-dependent density-functional theory (TDDFT) using random-phase approximation Hessians augmented with exact exchange contributions in various orders. It has been observed that this approach yields fairly accurate local valence excitations if combined with accurate asymptotically corrected exchange-correlation potentials used in the ground-state Kohn-Sham calculations. The inclusion of long-range particle-particle with hole-hole interactions in the kernel leads to errors of 0.14 eV only for the lowest excitations of a selection of three alkene, three carbonyl, and five azabenzene molecules, thus surpassing the accuracy of a number of common TDDFT and even some wave function correlation methods. In the case of long-range charge-transfer excitations, the method typically underestimates accurate reference excitation energies by 8% on average, which is better than with standard hybrid-GGA functionals but worse compared to range-separated functional approximations.
Excitation of high energy levels under laser exposure of suspensions of nanoparticles in liquids
Energy Technology Data Exchange (ETDEWEB)
Shafeev, G.A. [Wave Research Center of A.M. Prokhorov General Physics Institute, 38, Vavilov Street, 119991 Moscow (Russian Federation)], E-mail: shafeev@kapella.gpi.ru; Simakin, A.V. [Wave Research Center of A.M. Prokhorov General Physics Institute, 38, Vavilov Street, 119991 Moscow (Russian Federation); Bozon-Verduraz, F. [ITODYS, UMR CNRS 7086, Universite Paris 7-Denis Diderot, 2, place Jussieu, 75251 Paris cedex 05 (France); Robert, M. [Laboratoire d' Electrochimie Moleculaire, UMR CNRS 7591, Universite Paris 7 Denis Diderot, 2, place Jussieu, 75251 Paris cedex 05 (France)
2007-12-15
Laser exposure of suspensions of nanoparticles in liquids leads to excitation of high energy levels in both liquid and nanoparticle material. The emission spectrum of the colloidal solution under exposure of a suspension metallic nanoparticles in water to radiation of a Nd:YAG laser of a picosecond range of pulse duration is discussed. Excitation of nuclear energy levels and neutron release is experimentally studied on the model system of transmutation of Hg into Au that occurs under exposure of Hg nanodrops suspended in D{sub 2}O. The proposed mechanism involves: (i) emission of X-ray photons by Hg nanoparticles upon laser exposure, leading to neutron release from D{sub 2}O, (ii) initiation of Hg {yields} Au transmutation by the capture of neutrons. The effect of transmutation is more pronounced using {sup 196}Hg isotope instead of Hg of natural isotope composition. The influence of laser pulse duration on the degree of transmutation (from fs through ns range) is discussed.
International Nuclear Information System (INIS)
Hirakawa, Kazutaka; Segawa, Hiroshi
2016-01-01
Dendritic heptad molecules in which four pyrenyl groups are connected at the central phosphorus atom of the edge-porphyrins of the center-to-edge type porphyrin trimers were synthesized to investigate a multi-step excitation energy transfer. As the central energy acceptor, two types porphyrins which one was phosphorus(V)tetraphenylporphyrin (H2) and another was its derivative substituted by butoxy groups at four para-position of meso-phenyl groups (H1) were used. In the photoexcited state of the pyrene units, the excitation energy transfer to the central-porphyrin unit was observed in toluene. The excitation energy transfer is considered to be through two pathways; one is a stepwise pathway through the edge-porphyrin unit and another is a direct excitation energy transfer to the central porphyrin. The direct excitation energy transfer from pyrenes to the edge-porphyrin and central-porphyrin were observed in the case for H1. From the excited state of the edge-porphyrins, the excitation energy transfer to the central-porphyrin occurs in the H1 case. In the H2 case, the excitation energy of central-porphyrin is higher than that of H1, and the electron transfer from edge-porphyrin to the central-porphyrin become predominant process. - Highlights: • Dendritic pyrene-porphyrin heptads were synthesized. • Excitation energy transfer occurs from the pyrenyl moiety to the phosphorus(V)porphyrin. • The stepwise and direct energy transfer pathways were observed. • The quantum yields of these energy transfer pathways could be determined.
Energy Technology Data Exchange (ETDEWEB)
Hirakawa, Kazutaka, E-mail: hirakawa.kazutaka@shizuoka.ac.jp [Applied Chemistry and Biochemical Engineering Course, Department of Engineering, Graduate School of Integrated Science and Technology, Shizuoka University, Johoku 3-5-1, Naka-ku, Hamamatsu, Shizuoka 432-8561 (Japan); Department of Optoelectronics and Nanostructure Science, Graduate School of Science and Technology, Shizuoka University, Johoku 3-5-1, Naka-ku, Hamamatsu, Shizuoka 432-8561 (Japan); Segawa, Hiroshi [Department of Multi-Disciplinary Science - General Systems Studies, Graduate School of Arts and Sciences, The University of Tokyo, Komaba 3-8-1, Meguro-ku, Tokyo 153-8904 (Japan); Research Center for Advanced Science and Technology, The University of Tokyo, Komaba 4-6-1, Meguro-ku, Tokyo 153-8904 (Japan)
2016-11-15
Dendritic heptad molecules in which four pyrenyl groups are connected at the central phosphorus atom of the edge-porphyrins of the center-to-edge type porphyrin trimers were synthesized to investigate a multi-step excitation energy transfer. As the central energy acceptor, two types porphyrins which one was phosphorus(V)tetraphenylporphyrin (H2) and another was its derivative substituted by butoxy groups at four para-position of meso-phenyl groups (H1) were used. In the photoexcited state of the pyrene units, the excitation energy transfer to the central-porphyrin unit was observed in toluene. The excitation energy transfer is considered to be through two pathways; one is a stepwise pathway through the edge-porphyrin unit and another is a direct excitation energy transfer to the central porphyrin. The direct excitation energy transfer from pyrenes to the edge-porphyrin and central-porphyrin were observed in the case for H1. From the excited state of the edge-porphyrins, the excitation energy transfer to the central-porphyrin occurs in the H1 case. In the H2 case, the excitation energy of central-porphyrin is higher than that of H1, and the electron transfer from edge-porphyrin to the central-porphyrin become predominant process. - Highlights: • Dendritic pyrene-porphyrin heptads were synthesized. • Excitation energy transfer occurs from the pyrenyl moiety to the phosphorus(V)porphyrin. • The stepwise and direct energy transfer pathways were observed. • The quantum yields of these energy transfer pathways could be determined.
Dai, Quanqi; Harne, Ryan L.
2017-04-01
Effective development of vibration energy harvesters is required to convert ambient kinetic energy into useful electrical energy as power supply for sensors, for example in structural health monitoring applications. Energy harvesting structures exhibiting bistable nonlinearities have previously been shown to generate large alternating current (AC) power when excited so as to undergo snap-through responses between stable equilibria. Yet, most microelectronics in sensors require rectified voltages and hence direct current (DC) power. While researchers have studied DC power generation from bistable energy harvesters subjected to harmonic excitations, there remain important questions as to the promise of such harvester platforms when the excitations are more realistic and include both harmonic and random components. To close this knowledge gap, this research computationally and experimentally studies the DC power delivery from bistable energy harvesters subjected to such realistic excitation combinations as those found in practice. Based on the results, it is found that the ability for bistable energy harvesters to generate peak DC power is significantly reduced by introducing sufficient amount of stochastic excitations into an otherwise harmonic input. On the other hand, the elimination of a low amplitude, coexistent response regime by way of the additive noise promotes power delivery if the device was not originally excited to snap-through. The outcomes of this research indicate the necessity for comprehensive studies about the sensitivities of DC power generation from bistable energy harvester to practical excitation scenarios prior to their optimal deployment in applications.
Long-range interactions of excited He atoms with the alkaline earth atoms Mg, Ca, and Sr
Zhang, J.-Y.; Babb, J. F.; Mitroy, J.; Sadeghpour, H. R.; Schwingenschlö gl, Udo; Yan, Z.-C.
2013-01-01
Dispersion coefficients for the long-range interactions of the first four excited states of He, i.e., He(2 1, 3 S) and He(2 1, 3 P), with the low-lying states of the alkaline earth atoms Mg, Ca, and Sr are calculated by summing over the reduced matrix elements of multipole transition operators.
Long-range interactions of excited He atoms with the alkaline earth atoms Mg, Ca, and Sr
Zhang, J.-Y.
2013-04-05
Dispersion coefficients for the long-range interactions of the first four excited states of He, i.e., He(2 1, 3 S) and He(2 1, 3 P), with the low-lying states of the alkaline earth atoms Mg, Ca, and Sr are calculated by summing over the reduced matrix elements of multipole transition operators.
Xu, Wei-Qing; Xu, Long-Quan; Qi, De-Guang; Chen, Tao; Liu, Ya-Wei; Zhu, Lin-Fan
2018-04-01
The differential cross sections and generalized oscillator strengths for the low-lying excitations of the valence-shell 1eg orbital electron in ethane have been measured for the first time at a high incident electron energy of 1500 eV and a scattering angular range of 1.5°-10°. A weak feature, termed X here, with a band center of about 7.5 eV has been observed, which was also announced by the previous experimental and theoretical studies. The dynamic behaviors of the generalized oscillator strengths for the 3s (8.7 eV), 3s+3p (9.31 eV, 9.41 eV), and X (˜7.5 eV) transitions on the momentum transfer squared have been obtained. The integral cross sections of these transitions from their thresholds to 5000 eV have been obtained with the aid of the BE-scaling (B is the binding energy and E is the excitation energy) method. The optical oscillator strengths of the above transitions determined by extrapolating their generalized oscillator strengths to the limit of the squared momentum transfer K2 → 0 are in good agreement with the ones from the photoabsorption spectrum [J. W. Au et al., Chem. Phys. 173, 209 (1993)], which indicates that the present differential cross sections, generalized oscillator strengths, and integral cross sections can serve as benchmark data.
Satellite bands of the RbCs molecule in the range of highly excited states
Energy Technology Data Exchange (ETDEWEB)
Rakić, Mario; Beuc, Robert; Skenderović, Hrvoje, E-mail: hrvoje@ifs.hr [Institute of Physics, Bijenička cesta 46, Zagreb 10000 (Croatia); Bouloufa-Maafa, Nadia; Dulieu, Olivier; Vexiau, Romain [Laboratoire Aimé Cotton, CNRS, Université Paris-Sud, ENS Cachan, Université Paris-Saclay, Bât. 505, Campus d’Orsay, Orsay Cedex 91405 (France); Pichler, Goran [Physics Department, Kuwait University, PO Box 5969, Safat—13060 (Kuwait)
2016-05-28
We report on the observation of three RbCs satellite bands in the blue and green ranges of the visible spectrum. Absorption measurements are performed using all-sapphire cell filled with a mixture of Rb and Cs. We compare high resolution absorption spectrum of Rb-Cs vapor mixture with pure Rb and Cs vapor spectra from the literature. After detailed analysis, the new satellite bands of RbCs molecule at 418.3 nm, 468.3, and 527.5 nm are identified. The origin of these bands is discussed by direct comparison with difference potentials derived from quantum chemistry calculations of RbCs potential energy curves. These bands originate from the lower Rydberg states of the RbCs molecule. This study thus provides further insight into photoassociation of lower Rydberg molecular states, approximately between Cs(7s) + Rb(5s) and Cs(6s) + Rb(6p) asymptotes, in ultracold gases.
Long-range interactions of excited He atoms with ground-state noble-gas atoms
Zhang, J.-Y.
2013-10-09
The dispersion coefficients C6, C8, and C10 for long-range interactions of He(n1,3S) and He(n1,3P), 2≤n≤10, with the ground-state noble-gas atoms Ne, Ar, Kr, and Xe are calculated by summing over the reduced matrix elements of multipole transition operators. The large-n expansions for the sums over the He oscillator strength divided by the corresponding transition energy are presented for these series. Using the expansions, the C6 coefficients for the systems involving He(131,3S) and He(131,3P) are calculated and found to be in good agreement with directly calculated values.
International Nuclear Information System (INIS)
Stryganyuk, G.; Zimmerer, G.; Shiran, N.; Voronova, V.; Nesterkina, V.; Gektin, A.; Shimamura, K.; Villora, E.; Jing, F.; Shalapska, T.; Voloshinovskii, A.
2008-01-01
Spectral-kinetic study of Pr 3+ luminescence has been performed for LiLuF 4 :Pr(0.1 mol%) single crystal upon the excitation within 5-12 eV range at T=8 K. The fine-structure of Pr 3+ 4f 2 →4f 5d excitation spectra is shown for LiLuF 4 :Pr(0.1 mol%) to be affected by the efficient absorption transitions of Pr 3+ ions into 4f 5d involving 4f 1 core in the ground state. Favourable conditions have been revealed in LiLuF 4 :Pr(0.1 mol%) for the transformation of UV-VUV excitation quanta into the visible range. Lightly doped LiLuF 4 :Pr crystals are considered as the promising luminescent materials possessing the efficient Pr 3+3 P 0 visible emission upon UV-VUV excitation. The mechanism of energy transfer between Lu 3+ host ion and Pr 3+ impurity is discussed
Selective excitation, relaxation, and energy channeling in molecular systems
International Nuclear Information System (INIS)
Rhodes, W.C.
1993-08-01
Research involves theoretical studies of response, relaxation, and correlated motion in time-dependent behavior of large molecular systems ranging from polyatomic molecules to protein molecules in their natural environment. Underlying theme is subsystem modulation dynamics. Main idea is that quantum mechanical correlations between components of a system develop with time, playing a major role in determining the balance between coherent and dissipative forces. Central theme is interplay of coherence and dissipation in determining the nature of dynamic structuring and energy flow in molecular transformation mechanisms. Subsystem equations of motion are being developed to show how nonlinear, dissipative dynamics of a particular subsystem arise from correlated interactions with the rest of the system (substituent groups, solvent, lattice modes, etc.); one consequence is resonance structures and networks. Quantum dynamics and thermodynamics are being applied to understand control and energy transfer mechanisms in biological functions of protein molecules; these mechanisms are both global and local. Besides the above theory, the research deals with phenomenological aspects of molecular systems
Luminescence decay in condensed argon under high energy excitation
International Nuclear Information System (INIS)
Carvalho, M.J.; Klein, G.
1978-01-01
α and β particles were used to study the luminescence of condensed argon. The scintillation decay has always two components independently of the phase and the kind of the exciting particles. Decay time constants are given for solid, liquid and also gaseous argon. Changes in the relative intensity values of the two components are discussed in terms of track effects
Ordering and low energy excitations in strongly correlated bronzes
Sagara, Dodderi Manjunatha
2006-01-01
Summary In any solid system, whether it is superconducting, shows a charge-density-wave behavior, or any other kind of ground state, two aspects drag the attention of the scientific community. They are order and excitations in solids. The ordering may be due to electronic, lattice, spin or orbital
Range energy for heavy ions in CR-39
International Nuclear Information System (INIS)
Gil, L.R.; Marques, A.
1987-01-01
Range-energy relations in CR-39, for ions from He to Ar, are obtained after their effective nuclear charge. Comparison with earlier calculations and numerical results in the energy range 0,1 to 200 Mev/ Nucleon are also given. (M.W.O.)
Ab initio theoretical calculations of the electronic excitation energies of small water clusters.
Tachikawa, Hiroto; Yabushita, Akihiro; Kawasaki, Masahiro
2011-12-14
A direct ab initio molecular dynamics method has been applied to a water monomer and water clusters (H(2)O)(n) (n = 1-3) to elucidate the effects of zero-point energy (ZPE) vibration on the absorption spectra of water clusters. Static ab initio calculations without ZPE showed that the first electronic transitions of (H(2)O)(n), (1)B(1)←(1)A(1), are blue-shifted as a function of cluster size (n): 7.38 eV (n = 1), 7.58 eV (n = 2) and 8.01 eV (n = 3). The inclusion of the ZPE vibration strongly affects the excitation energies of a water dimer, and a long red-tail appears in the range of 6.42-6.90 eV due to the structural flexibility of a water dimer. The ultraviolet photodissociation of water clusters and water ice surfaces is relevant to these results.
Harne, R. L.; Zhang, Chunlin; Li, Bing; Wang, K. W.
2016-07-01
Impulsive energies are abundant throughout the natural and built environments, for instance as stimulated by wind gusts, foot-steps, or vehicle-road interactions. In the interest of maximizing the sustainability of society's technological developments, one idea is to capture these high-amplitude and abrupt energies and convert them into usable electrical power such as for sensors which otherwise rely on less sustainable power supplies. In this spirit, the considerable sensitivity to impulse-type events previously uncovered for bistable oscillators has motivated recent experimental and numerical studies on the power generation performance of bistable vibration energy harvesters. To lead to an effective and efficient predictive tool and design guide, this research develops a new analytical approach to estimate the electroelastic response and power generation of a bistable energy harvester when excited by an impulse. Comparison with values determined by direct simulation of the governing equations shows that the analytically predicted net converted energies are very accurate for a wide range of impulse strengths. Extensive experimental investigations are undertaken to validate the analytical approach and it is seen that the predicted estimates of the impulsive energy conversion are in excellent agreement with the measurements, and the detailed structural dynamics are correctly reproduced. As a result, the analytical approach represents a significant leap forward in the understanding of how to effectively leverage bistable structures as energy harvesting devices and introduces new means to elucidate the transient and far-from-equilibrium dynamics of nonlinear systems more generally.
Energy Technology Data Exchange (ETDEWEB)
Lan, C. B.; Qin, W. Y. [Department of Engineering Mechanics, Northwestern Polytechnical University, Xi' an 710072 (China)
2014-09-15
This letter investigates the energy harvesting from the horizontal coherent resonance of a vertical cantilever beam subjected to the vertical base excitation. The potential energy of the system has two symmetric potential wells. So, under vertical excitation, the system can jump between two potential wells, which will lead to the large vibration in horizontal direction. Two piezoelectric patches are pasted to harvest the energy. From experiment, it is found that the vertical excitation can make the beam turn to be bistable. The system can transform vertical vibration into horizontal vibration of low frequency when excited by harmonic motion. The horizontal coherence resonance can be observed when excited by a vertical white noise. The corresponding output voltages of piezoelectric films reach high values.
On mechanism of Ar(3p54p) states excitation in low-energy Ar-Ar collisions
International Nuclear Information System (INIS)
Kurskov, S Y; Kashuba, A S
2009-01-01
The present work is devoted to study of Ar(3p 5 4p) states excitation in binary low-energy Ar-Ar collisions. The results of the experimental investigation of excitation cross sections of Ar I 4p'[l/2] 1 , 4p'[3/2] 1 , 4p'[3/2] 2 and 4p[3/2] 2 levels in the collision energy range from threshold up to 500 eV (cm) and degree of polarization for 4s[3/2] 2 0 -4p'[l/2] 1 and 4s[3/2] 2 0 -4p[3/2] 2 transitions in this energy range are represented.
Ioniclike energy structure of neutral core-excited states in free Kr clusters
International Nuclear Information System (INIS)
Peredkov, S.; Sorensen, S.L.; Kivimaeki, A.; Schulz, J.; Maartensson, N.; Oehrwall, G.; Lundwall, M.; Rander, T.; Lindblad, A.; Bergersen, H.; Svensson, S.; Bjoerneholm, O.; Tchaplyguine, M.
2005-01-01
The development of electronic states in krypton clusters is investigated by high-resolution core-level electron spectroscopy. The energy ordering of bulk versus surface 3d -1 np(n>5) core-excited states in neutral clusters is demonstrated to be reversed to the 3d -1 5p level situation. The cluster 3d -1 6p,7p states are proven to be at a lower energy than the corresponding atomic levels. These findings reveal the ioniclike energy structure of the neutral cluster core-excited levels. The phenomenon is explained by a spatial spread of the excited orbitals over the cluster lattice
Energy transfer and quenching processes of excited uranyl ion and lanthanide ions in solutions
International Nuclear Information System (INIS)
Yamamura, Tomoo; Tomiyasu, Hiroshi
1995-01-01
Deactivation processes of photoexcited uranyl ion by various lanthanide ions in aqueous solution were studied. Each lanthanide ions show different interaction with excited uranyl ion depending on its lowest excited energy level, the number of 4f electrons and the acid concentration of the solution. (author)
DEFF Research Database (Denmark)
Sauer, Stephan P. A.; Pitzner-Frydendahl, Henrik Frank; Buse, Mogens
2015-01-01
methods, the original SOPPA method as well as SOPPA(CCSD) and RPA(D) in the calculation of vertical electronic excitation energies and oscillator strengths is investigated for a large benchmark set of 28 medium-size molecules with 139 singlet and 71 triplet excited states. The results are compared...
Energy Technology Data Exchange (ETDEWEB)
Zhuravlev, K. [V.A. Kotelnikov Institute of Radioengineering and Electronics of RAS, 1 Vvedenskii sq., Fryazino Moscow reg. 141190 (Russian Federation); Tsaryuk, V., E-mail: vit225@ire216.msk.s [V.A. Kotelnikov Institute of Radioengineering and Electronics of RAS, 1 Vvedenskii sq., Fryazino Moscow reg. 141190 (Russian Federation); Kudryashova, V.; Pekareva, I. [V.A. Kotelnikov Institute of Radioengineering and Electronics of RAS, 1 Vvedenskii sq., Fryazino Moscow reg. 141190 (Russian Federation); Sokolnicki, J. [Faculty of Chemistry, University of WrocLaw, 14 F. Joliot-Curie str., WrocLaw 50-383 (Poland); Yakovlev, Yu. [V.A. Kotelnikov Institute of Radioengineering and Electronics of RAS, 1 Vvedenskii sq., Fryazino Moscow reg. 141190 (Russian Federation)
2010-08-15
A series of compounds Ln(RCOO){sub 3}.Phen (Ln=Eu, Gd, Tb; RCOO{sup -}-1- and 2-naphthoate, 1- and 2-naphthylacetate, 1- and 2-naphthoxyacetate anions, Phen-1,10-phenanthroline) was investigated by methods of optical spectroscopy. Compounds of composition Ln(RCOO){sub 3}.nH{sub 2}O with the same carboxylate ligands are also considered. Results of studies of the effects of methylene spacer decoupling the {pi}-{pi}- or p-{pi}-conjugation in the naphthylcarboxylate ligand on the structure of Eu{sup 3+} coordination centre, on the lifetime of {sup 5}D{sub 0} (Eu{sup 3+}) state, and on processes of the excitation energy transfer to Eu{sup 3+} or Tb{sup 3+} ions are presented. Introduction of the methylene bridge in the ligand weakens the influence of the steric hindrances in forming of a crystal lattice and results in lowering the distortion of the Eu{sup 3+} luminescence centre, and in elongation of the observed {sup 5}D{sub 0} lifetime {tau}{sub obs}. The latter is caused by decrease in contribution of the radiative processes rate 1/{tau}{sub r}. This is confirmed by the correlation between the lifetimes {tau}{sub obs} and the quantities '{tau}{sub r}.const' inversely proportional to the total integral intensities of Eu(RCOO){sub 3}.Phen luminescence spectra. The methylene spacer performs a role of regulator of sensitization of the Ln{sup 3+} luminescence efficiency by means of an influence on mutual location of lowest triplet states of the ligands, the ligand-metal charge transfer (LMCT) states, and the emitting states of Ln{sup 3+} ions. The lowest triplet state in lanthanide naphthylcarboxylate adducts with Phen is related to carboxylate anion. A presence of the methylene spacer in naphthylcarboxylate ligand increases the triplet state energy. At the same time, the energy of 'carboxylic group-Eu{sup 3+} ion' charge transfer states falls, which can promote the degradation of excitation energy. In naphthylcarboxylates investigated a range of the
Hadron fragment emission in cluster excitation processes at medium energies
International Nuclear Information System (INIS)
Kovacs, Zs.
1985-12-01
An extended version of the cluster excitation model is proposed to describe the emission of various particle types in nuclear reactions in a consistent way. At first pion, proton deuteron and triton spectra from neutron-carbon interactions at 545 MeV in the angular region from deg 73 to deg 165 were tried to interpret by the model. The results are compared with model calculations. (author)
Quasi-particle excitations in low energy fission
International Nuclear Information System (INIS)
Ashgar, M.; Djebara, M.; Bocquet, J.P.; Brissot, R.; Maurel, M.; Nifenecker, H.; Ristori, C.
1985-05-01
Proton odd-even effect for 229 Th(nsub(th),f) and 232 U(nsub(th),f) has been determined with a ΔE-Esub(R) gas telescope. These data indicate that the qp-particle excitation probability at the saddle point is small and most of its results, when the nucleus moves from saddle to scission and the neck ruptures into final fragments. These results are discussed in terms of the different ideas and models
Velasco, A M; Lavín, C; Dolgounitcheva, O; Ortiz, J V
2014-08-21
Vertical excitation energies of the methyl and silyl radicals were inferred from ab initio electron propagator calculations on the electron affinities of CH3(+) and SiH3(+). Photoionization cross sections and angular distribution of photoelectrons for the outermost orbitals of both CH3 and SiH3 radicals have been obtained with the Molecular Quantum Defect Orbital method. The individual ionization cross sections corresponding to the Rydberg channels to which the excitation of the ground state's outermost electron gives rise are reported. Despite the relevance of methyl radical in atmospheric chemistry and combustion processes, only data for the photon energy range of 10-11 eV seem to be available. Good agreement has been found with experiment for photoionization cross section of this radical. To our knowledge, predictions of the above mentioned photoionization parameters on silyl radical are made here for the first time, and we are not aware of any reported experimental measurements. An analysis of our results reveals the presence of a Cooper minimum in the photoionization of the silyl radical. The adequacy of the two theoretical procedures employed in the present work is discussed.
Optogalvanic monitoring of collisional transfer of laser excitation energy in a neon RF plasma
International Nuclear Information System (INIS)
Armstrong, T.D.
1994-01-01
The optogalvanic signals produced by pulsed laser excitation of 1s5--2p8 and 1s5-2p9 (Paschen notation) transition by a ∼29 MHz radiofrequency (rf) discharge at ∼5 torr have been investigated. The optogalvanic signal produced by 1s5-2p9 excitations indicates that there is transfer of energy from the 2p9 state to some other state. The state to which this energy is transferred is believed to be mainly the 2p8 state because of the very small energy gap between the 2p9 and 2p8 states. To verify this transfer, the 1s5-2p8 transition was investigated. The similarity of the temporal profiles of the optogalvanic signals in both excitations confirms the collisional transfer of laser excitation energy from 2p9 to 2p8
Proceedings of the 1984 workshop on high-energy excitations in condensed matter. Volume II
International Nuclear Information System (INIS)
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
Effect of Optical Excitation Energy on the Red Luminescence of Eu(3+) in GaN
National Research Council Canada - National Science Library
Peng, H. Y; Lee, C. W; Everitt, H. O; Lee, D. S; Steckl, A. J; Zavada, J. M
2005-01-01
...)] transition from GaN:Eu. Time-resolved PL measurements revealed that for excitation at the GaN bound exciton energy, the decay transients are almost temperature insensitive between 86 K and 300 K, indicating an efficient...
Energy-range relations for hadrons in nuclear matter
Strugalski, Z.
1985-01-01
Range-energy relations for hadrons in nuclear matter exist similarly to the range-energy relations for charged particles in materials. When hadrons of GeV kinetic energies collide with atomic nuclei massive enough, events occur in which incident hadron is stopped completely inside the target nucleus without causing particle production - without pion production in particular. The stoppings are always accompanied by intensive emission of nucleons with kinetic energy from about 20 up to about 400 MeV. It was shown experimentally that the mean number of the emitted nucleons is a measure of the mean path in nuclear matter in nucleons on which the incident hadrons are stopped.
Long-range outlook of energy demands and supplies
International Nuclear Information System (INIS)
1984-01-01
An interim report on the long-range outlook of energy demands and supplies in Japan as prepared by an ad hoc committee, Advisory Committee for Energy was given for the period up to the year 2000. As the energy demands in terms of crude oil, the following figures are set: 460 million kl for 1990, 530 million kl for 1995, and 600 million kl for 2000. In Japan, without domestic energy resources, over 80% of the primary energy has been imported; the reliance on Middle East where political situation is unstable, for petroleum is very large. The following things are described. Background and policy; energy demands in industries, transports, and people's livelihood; energy supplies by coal, nuclear energy, petroleum, etc.; energy demand/supply outlook for 2000. (Mori, K.)
Excitation energy of the lowest 2+ and 3- levels in 32Mg and 146Gd
International Nuclear Information System (INIS)
Barranco, M.; Lombard, R.J.
1978-06-01
The excitation energy of the lowest 2 + and 3 - levels are calculated for neutron rich Mg-isotopes as well as for N=82 isotones. The calculations are made by assuming quadrupole-quadrupole and octupole-octupole forces. The quasi-particles energies and occupation numbers are taken from the energy density method
Effect of magnetic field on the impurity binding energy of the excited ...
Indian Academy of Sciences (India)
The effect of external magnetic field on the excited state energies in a spherical quantum dot was studied. The impurity energy and binding energy were calculated using the variational method within the effective mass approximation and finite barrier potential. The results showed that by increasing the magnetic field, the ...
Effect of magnetic field on the impurity binding energy of the excited ...
Indian Academy of Sciences (India)
Abstract. The effect of external magnetic field on the excited state energies in a spher- ical quantum dot was studied. The impurity energy and binding energy were calculated using the variational method within the effective mass approximation and finite barrier potential. The results showed that by increasing the magnetic ...
Energy risk management through self-exciting marked point process
International Nuclear Information System (INIS)
Herrera, Rodrigo
2013-01-01
Crude oil is a dynamically traded commodity that affects many economies. We propose a collection of marked self-exciting point processes with dependent arrival rates for extreme events in oil markets and related risk measures. The models treat the time among extreme events in oil markets as a stochastic process. The main advantage of this approach is its capability to capture the short, medium and long-term behavior of extremes without involving an arbitrary stochastic volatility model or a prefiltration of the data, as is common in extreme value theory applications. We make use of the proposed model in order to obtain an improved estimate for the Value at Risk in oil markets. Empirical findings suggest that the reliability and stability of Value at Risk estimates improve as a result of finer modeling approach. This is supported by an empirical application in the representative West Texas Intermediate (WTI) and Brent crude oil markets. - Highlights: • We propose marked self-exciting point processes for extreme events in oil markets. • This approach captures the short and long-term behavior of extremes. • We improve the estimates for the VaR in the WTI and Brent crude oil markets
Piezoelectric Wind Energy Harvesting from Self-Excited Vibration of Square Cylinder
Directory of Open Access Journals (Sweden)
Junlei Wang
2016-01-01
Full Text Available Self-excited vibration of a square cylinder has been considered as an effective way in harvesting piezoelectric wind energy. In present work, both of the vortex-induced vibration and unstable galloping phenomenon process are investigated in a reduced velocity (Ur=U/ωn·D range of 4≤Ur≤20 with load resistance ranging in 100 Ω≤R≤1 MΩ. The vortex-induced vibration covers presynchronization, synchronization, and postsynchronization branches. An aeroelectromechanical model is given to describe the coupling of the dynamic equation of the fluid-structure interaction and the equation of Gauss law. The effects of load resistance are investigated in both the open-circuit and close-circuit system by a linear analysis, which covers the parameters of the transverse displacement, aerodynamic force, output voltage, and harvested power utilized to measure the efficiency of the system. The highest level of the transverse displacement and the maximum value of harvested power of synchronization branch during the vortex-induced vibration and galloping are obtained. The results show that the large-amplitude galloping at high wind speeds can generate energy. Additionally, energy can be harvested by utilization of the lock-in phenomenon of vortex-induced vibration under low wind speed.
High-sensitivity measurements of the excitation function for Bhabha scattering at MeV energies
International Nuclear Information System (INIS)
Tsertos, H.; Kozhuharov, C.; Armbruster, P.; Kienle, P.; Krusche, B.; Schreckenbach, K.
1989-02-01
Using a monochromatic e + beam scattered on a Be foil and a high-resolution detector device, the excitation function for elastic e + e - scattering was measured with a statistical accuracy of 0.25% in 1.4 keV steps in the c.m.-energy range between 770 keV and 840 keV (1.79 - 1.86 MeV/c 2 ) at c.m. scattering angles between 80 0 and 100 0 (FWHM). Within the experimental sensitivity of 0.5 b.eV/sr (c.m.) for the energy-integrated differential cross section no resonances were observed (97% CL). From this limit we infer that a hypothetical spinless resonant state should have a width of less than 1.9 meV corresponding to a lifetime limit of 3.5x10 -13 s. This limit establishes the most stringent bound for new particles in this mass range derived from Bhabha scattering and is independent of assumptions about the internal structure of the hypothetical particles. Less sensitivite limits were, in addition, derived around 520 keV c.m. energy (≅ 1.54 MeV/c 2 ) from an investigation with a thorium and a mylar foil as scatterers. (orig.)
The structure of nuclear states at low, intermediate and high excitation energies
International Nuclear Information System (INIS)
Soloviev, V.G.
1976-01-01
It is shown that within the model based on the quasiparticle-phonon interaction one can obtain the description of few-quasiparticle components of nuclear states at low, intermediate and high excitation energies. For the low-lying states the energy of each level is calculated. The few-quasiparticle components at intermediate and high excitation energies are represented to be averaged in certain energy intervals and their characteri stics are given as the corresponding strength functions. The fragmentation of single-particle states in deformed nuclei is studied. It is shown that in the distribution of the single-particle strength alongside with a large maximum there appear local maxima and the distribution itself has a long tail. The dependence of neutron strength functions on the excitation energy is investigated for the transfer reaction of the type (d,p) and (d,t). The s,- p,- and d-wave neutron strength functions are calculated at the neutron binding energy Bn. A satisfactory agreement with experiment is obtained. The energies and Elambda-strength functions for giant multipole resonances in deformed nuclei are calculated. The energies of giant quadrupole and octupole resonances are calculated. Their widths and fine structure are being studied. It is stated that to study the structure of highly excited states it is necessary to find the values of many-quasiparticle components of the wave functions. The ways of experimental determination of these components based on the study of γ-transitions between highly excited states are discussed
Excitation energy deactivation funnel in 3-substituted BODIPY-porphyrin conjugate
International Nuclear Information System (INIS)
Nguyen, Nguyen Tran; Verbelen, Bram; Leen, Volker; Waelkens, Etienne; Dehaen, Wim; Kruk, Mikalai
2016-01-01
BODIPYs absorb in the visible region which is complementary to that of porphyrins and therefore can be suggested as promising antenna groups to improve the light-harvesting potential of porphyrins. A boron-dipyrromethene dye was combined at the 3-position with a Zn-porphyrin to afford a conjugate. The fluorescence of the conjugate was found to originate from the BODIPY moiety independently of the excitation wavelength due to an unique set of energy transfer rates between the BODIPY and Zn-porphyrin moieties. The fluorescence intensity was shown to be tunable over a wide range using the solvent properties. This feature makes the studied BODIPY-porphyrin conjugate a promising compound for the design of new photochromic devices.
Excitation energy deactivation funnel in 3-substituted BODIPY-porphyrin conjugate
Energy Technology Data Exchange (ETDEWEB)
Nguyen, Nguyen Tran [Chemistry Department, University of Education, The University of DaNang, Ton Duc Thang 459, Da Nang (Viet Nam); Molecular Design and Synthesis, Department of Chemistry, KU Leuven, Celestijnenlaan 200F, B-3001 Leuven (Belgium); Verbelen, Bram; Leen, Volker [Molecular Design and Synthesis, Department of Chemistry, KU Leuven, Celestijnenlaan 200F, B-3001 Leuven (Belgium); Waelkens, Etienne [Department of Cellular and Molecular Medicine, KU Leuven, Herestraat 49, Box 901, 3000 Leuven (Belgium); Dehaen, Wim, E-mail: wim.dehaen@kuleuven.be [Molecular Design and Synthesis, Department of Chemistry, KU Leuven, Celestijnenlaan 200F, B-3001 Leuven (Belgium); Kruk, Mikalai, E-mail: m.kruk@belstu.by [Belarusian State Technological University, Physics Department, Sverdlov Str., 13a, Minsk 220006 (Belarus)
2016-11-15
BODIPYs absorb in the visible region which is complementary to that of porphyrins and therefore can be suggested as promising antenna groups to improve the light-harvesting potential of porphyrins. A boron-dipyrromethene dye was combined at the 3-position with a Zn-porphyrin to afford a conjugate. The fluorescence of the conjugate was found to originate from the BODIPY moiety independently of the excitation wavelength due to an unique set of energy transfer rates between the BODIPY and Zn-porphyrin moieties. The fluorescence intensity was shown to be tunable over a wide range using the solvent properties. This feature makes the studied BODIPY-porphyrin conjugate a promising compound for the design of new photochromic devices.
Excited baryon form-factors at high momentum transfer at CEBAF at higher energies
Energy Technology Data Exchange (ETDEWEB)
Stoler, P. [Rensselaer Polytechnic Inst., Troy, NY (United States)
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.
Influence of donor-donor transport on excitation energy transfer
Energy Technology Data Exchange (ETDEWEB)
Pandey, K K; Joshi, H C; Pant, T C [Kumaun University, Nainital (India). Department of Physics
1989-01-01
Energy migration and transfer from acriflavine to rhodamine B and malachite green in poly (methylmethacrylate) have been investigated using the decay function analysis. It is found that the influence of energy migration in energy transfer can be described quite convincingly by making use of the theories of Loring, Andersen and Fayer (LAF) and Huber. At high acceptor concentration direct donor-acceptor transfer occurs through Forster mechanism. (author). 17 refs., 5 figs.
Grosveld, Ferdinand W.
1990-01-01
The feasibility of predicting interior noise due to random acoustic or turbulent boundary layer excitation was investigated in experiments in which a statistical energy analysis model (VAPEPS) was used to analyze measurements of the acceleration response and sound transmission of flat aluminum, lucite, and graphite/epoxy plates exposed to random acoustic or turbulent boundary layer excitation. The noise reduction of the plate, when backed by a shallow cavity and excited by a turbulent boundary layer, was predicted using a simplified theory based on the assumption of adiabatic compression of the fluid in the cavity. The predicted plate acceleration response was used as input in the noise reduction prediction. Reasonable agreement was found between the predictions and the measured noise reduction in the frequency range 315-1000 Hz.
Fission of 255,256Es, 255-257Fm, and 258Md at moderate excitation energies
Britt, H.C.; Hoffman, D.C.; Plicht, J. van der; Wilhelmy, J.; Cheifetz, E.; Dupzyk, R.J.; Lougheed, R.W.
1984-01-01
The fission of 255,256Es, 255-257Fm, and 258Md has been studied in the excitation energy range from threshold to 25 MeV. A target of 254Es was used in the direct reaction studies; (d,pf), (t,pf), (3He,df), (3He,pf), and in the compound induced fission reactions formed with p, d, t, and α particle
Battery electric vehicle energy consumption modelling for range estimation
Wang, J.; Besselink, I.J.M.; Nijmeijer, H.
2017-01-01
Range anxiety is considered as one of the major barriers to the mass adoption of battery electric vehicles (BEVs). One method to solve this problem is to provide accurate range estimation to the driver. This paper describes a vehicle energy consumption model considering the influence of weather
Pandey, Laxman; Doiron, Curtis; Sears, John S.; Bré das, Jean-Luc
2012-01-01
Polymers with low optical gaps are of importance to the organic photovoltaics community due to their potential for harnessing a large portion of the solar energy spectrum. The combination along their backbones of electron-rich and electron-deficient fragments contributes to the presence of low-lying excited states that are expected to display significant charge-transfer character. While conventional hybrid functionals are known to provide unsatisfactory results for charge-transfer excitations at the time-dependent DFT level, long-range corrected (LRC) functionals have been reported to give improved descriptions in a number of systems. Here, we use such LRC functionals, considering both tuned and default range-separation parameters, to characterize the absorption spectra of low-optical-gap systems of interest. Our results indicate that tuned LRC functionals lead to simulated optical-absorption properties in good agreement with experimental data. Importantly, the lowest-lying excited states (excitons) are shown to present a much more localized nature than initially anticipated. © 2012 the Owner Societies.
Isobar excitations and low energy spectra of light nuclei
International Nuclear Information System (INIS)
Czerski, P.
1984-01-01
The aim of this investigation is to study the possible influence of inner excitations of nucleons into the Δ(3,3)-resonance on the low lying spectra of light nuclei like 12 C and 16 O. Before we can study the effect of such exotic configurations one has to perform a reliable investigation within the normal nuclear model, which is based on a microscopic theory. This is achieved by performing RPA (Random Phase Approximation) calculations using a realistic residual interaction derived from the Brueckner G-matrix. An efficient parametrisation of the residual interaction is introduced and the reliability of the more phenomenological parametrisations which are generally used is discussed. Within such realistic calculations, the isobar effects are small. (orig.) [de
σ-SCF: A direct energy-targeting method to mean-field excited states.
Ye, Hong-Zhou; Welborn, Matthew; Ricke, Nathan D; Van Voorhis, Troy
2017-12-07
The mean-field solutions of electronic excited states are much less accessible than ground state (e.g., Hartree-Fock) solutions. Energy-based optimization methods for excited states, like Δ-SCF (self-consistent field), tend to fall into the lowest solution consistent with a given symmetry-a problem known as "variational collapse." In this work, we combine the ideas of direct energy-targeting and variance-based optimization in order to describe excited states at the mean-field level. The resulting method, σ-SCF, has several advantages. First, it allows one to target any desired excited state by specifying a single parameter: a guess of the energy of that state. It can therefore, in principle, find all excited states. Second, it avoids variational collapse by using a variance-based, unconstrained local minimization. As a consequence, all states-ground or excited-are treated on an equal footing. Third, it provides an alternate approach to locate Δ-SCF solutions that are otherwise hardly accessible by the usual non-aufbau configuration initial guess. We present results for this new method for small atoms (He, Be) and molecules (H 2 , HF). We find that σ-SCF is very effective at locating excited states, including individual, high energy excitations within a dense manifold of excited states. Like all single determinant methods, σ-SCF shows prominent spin-symmetry breaking for open shell states and our results suggest that this method could be further improved with spin projection.
Manser, Joseph S.
The burgeoning class of metal halide perovskites constitutes a paradigm shift in the study and application of solution-processed semiconductors. Advancements in thin film processing and our understanding of the underlying structural, photophysical, and electronic properties of these materials over the past five years have led to development of perovskite solar cells with power conversion efficiencies that rival much more mature first and second-generation commercial technologies. It seems only a matter of time before the real-world impact of these compounds is put to the test. Like oxide perovskites, metal halide perovskites have ABX3 stoichiometry, where typically A is a monovalent cation, B a bivalent post-transition metal, and X a halide anion. Characterizing the behavior of photogenerated charges in metal halide perovskites is integral for understanding the operating principles and fundamental limitations of perovskite optoelectronics. The majority of studies outlined in this dissertation involve fundamental study of the prototypical organic-inorganic compound methylammonium lead iodide (CH3NH3PbI 3). Time-resolved pump-probe spectroscopy serves as a principle tool in these investigations. Excitation of a semiconductor can lead to formation of a number different excited state species and electronic complexes. Through analysis of excited state decay kinetics and optical nonlinearities in perovskite thin films, we identify spontaneous formation of a large fraction of free electrons and holes, whose presence is requisite for efficient photovoltaic operation. Following photogeneration of charge carriers in a semiconductor absorber, these species must travel large distances across the thickness of the material to realize large external quantum efficiencies and efficient carrier extraction. Using a powerful technique known as transient absorption microscopy, we directly image long-range carrier diffusion in a CH3NH3PbI 3 thin film. Charges are unambiguously shown to
Long-range prospects of world energy demands and future energy sources
International Nuclear Information System (INIS)
Kozaki, Yasuji
1998-01-01
The long-range prospects for world energy demands are reviewed, and the major factors which are influential in relation to energy demands are discussed. The potential for various kinds of conventional and new energy sources such as fossil fuels, solar energies, nuclear fission, and fusion energies to need future energy demands is also discussed. (author)
Influence of collision energy and vibrational excitation on the ...
Indian Academy of Sciences (India)
tions of potential energy surface (PES) for BrH2 system are more ... rier heights for both the exchange and abstraction are smaller than ... The complete picture on the dynamics of ..... Kurosaki Y and Takayanagi T private communication. 20.
Energy Technology Data Exchange (ETDEWEB)
Shamim, Md; Harbola, Manoj K, E-mail: sami@iitk.ac.i, E-mail: mkh@iitk.ac.i [Department of Physics, Indian Institute of Technology, Kanpur 208 016 (India)
2010-11-14
Transition energies of a new class of excited states (two-gap systems) of various atoms are calculated in time-independent density functional formalism by using a recently proposed local density approximation exchange energy functional for excited states. It is shown that the excitation energies calculated with this functional compare well with those calculated with exact exchange theories.
International Nuclear Information System (INIS)
Shamim, Md; Harbola, Manoj K
2010-01-01
Transition energies of a new class of excited states (two-gap systems) of various atoms are calculated in time-independent density functional formalism by using a recently proposed local density approximation exchange energy functional for excited states. It is shown that the excitation energies calculated with this functional compare well with those calculated with exact exchange theories.
Energy Technology Data Exchange (ETDEWEB)
Pietralla, N., E-mail: pietralla@ikp.tu-darmstadt.d [Institut fuer Kernphysik, Technische Universitaet Darmstadt, 64289 Darmstadt (Germany); Nuclear Structure Laboratory, SUNY at Stony Brook, Stony Brook, NY 11794-3800 (United States); Institut fuer Kernphysik, Universitaet zu Koeln, 50937 Koeln (Germany); Li, T.C. [Nuclear Structure Laboratory, SUNY at Stony Brook, Stony Brook, NY 11794-3800 (United States); Fritzsche, M. [Institut fuer Kernphysik, Technische Universitaet Darmstadt, 64289 Darmstadt (Germany); Ahmed, M.W. [Triangle Universities Nuclear Laboratory (TUNL), Duke University, Durham, NC 27708 (United States); Ahn, T.; Costin, A. [Institut fuer Kernphysik, Technische Universitaet Darmstadt, 64289 Darmstadt (Germany); Nuclear Structure Laboratory, SUNY at Stony Brook, Stony Brook, NY 11794-3800 (United States); Institut fuer Kernphysik, Universitaet zu Koeln, 50937 Koeln (Germany); Enders, J. [Institut fuer Kernphysik, Technische Universitaet Darmstadt, 64289 Darmstadt (Germany); Li, J. [Duke Free Electron Laser Laboratory (DFELL), Duke University, Durham, NC 27708 (United States); Mueller, S.; Neumann-Cosel, P. von [Institut fuer Kernphysik, Technische Universitaet Darmstadt, 64289 Darmstadt (Germany); Pinayev, I.V. [Duke Free Electron Laser Laboratory (DFELL), Duke University, Durham, NC 27708 (United States); Ponomarev, V.Yu.; Savran, D. [Institut fuer Kernphysik, Technische Universitaet Darmstadt, 64289 Darmstadt (Germany); Tonchev, A.P.; Tornow, W.; Weller, H.R. [Triangle Universities Nuclear Laboratory (TUNL), Duke University, Durham, NC 27708 (United States); Werner, V. [A.W. Wright Nuclear Structure Laboratory (WNSL), Yale University, New Haven, CT (United States); Wu, Y.K. [Duke Free Electron Laser Laboratory (DFELL), Duke University, Durham, NC 27708 (United States); Zilges, A. [Institut fuer Kernphysik, Universitaet zu Koeln, 50937 Koeln (Germany)
2009-10-26
The Pb(gamma{sup -}>,gamma{sup '}) photon scattering reaction has been studied with the nearly monochromatic, linearly polarized photon beams at the High Intensity gamma-ray Source (HIgammaS) at the DFELL. Azimuthal scattering intensity asymmetries measured with respect to the polarization plane of the beam have been used for the first time to assign both the spin and parity quantum numbers of dipole excited states of {sup 206,207,208}Pb at excitation energies in the vicinity of 5.5 MeV. Evidence for dominant particle-core coupling is deduced from these results along with information on excitation energies and electromagnetic transition matrix elements. Implications of the existence of weakly coupled states built on highly excited core states in competition with 1homega single particle (hole) excitations at comparable energies are discussed.
Plasmon assisted control of photo-induced excitation energy transfer in a molecular chain
Wang, Luxia; May, Volkhard
2017-08-01
The strong and ultrafast laser pulse excitation of a molecular chain in close vicinity to a spherical metal nano-particle (MNP) is studied theoretically. Due to local-field enhancement around the MNP, pronounced excited-state formation has to be expected for the part of the chain which is in proximity to the MNP. Here, the description of this phenomenon will be based on a uniform quantum theory of the MNP-molecule system. It accounts for local-field effects due to direct consideration of the strong excitation energy transfer coupling between the MNP and the various molecules. The molecule-MNP distances are chosen in such a way as to achieve a correct description of the MNP via dipole-plasmon excitations. Short plasmon life-times are incorporated in the framework of a density matrix approach. By extending earlier work the present description allows for multi-exciton formation and multiple dipole-plasmon excitation. The region of less intense and not-too-short optical excitation is identified as being best suited for excitation energy localization in the chain.
International Nuclear Information System (INIS)
Kuzin, A.; Thompson, M.N.; Rassool, R.; Adler, J.O.; Fissum, K.; Issaksson, L.; Ruijter, H.; Schroeder, B.; Annand, J.R.M.; McGeorge, J.C.; Crawford, G.I.; Gregel, J.
1997-01-01
The 12 C (γ,p) reaction was studied. The experiment was done at the MAX Laboratory of Lund University, using tagged photons with energy between 50 and 70 MeV and natural carbon targets. It has been possible to detect γ-ray emitted from the residual nucleus, in coincidence with photoprotons leading to the excited residual state. The 200 KeV gamma-ray resolution permitted the identification of the residual states and allowed off-line cuts to be made in order to identify the excitation region in 11 B from what particular de-excitation gamma-ray were seen. 9 refs., 1 tab., 3 figs
Study of excitation energy sharing in heavy ion collisions as a function of their inelasticity
International Nuclear Information System (INIS)
Lott, B.
1986-01-01
The excitation energy sharing between the fragments of a heavy ion collision has been studied for quasi-elastic and deep inelastic mechanisms. A 32 S beam of 232 MeV incident energy has been used to bombard several targets (S, 58 Ni, 93 Nb). The evaporated charged particle multiplicities have been measured by inclusive measurements of the projectile-like nuclei and exclusive measurements of the two final nuclei. Evaporation calculations using the Hauser-Feshbach formalism allows us to deduce from the multiplicity measurements the projectile-like excitation energy. These results are compatible with the assumption of an equal sharing of excitation energies for quasi-elastic reaction products, and with the assumption of a mass ratio sharing for fully relaxed reaction products. Limiting values for the relaxation time of this mode have been deduced and are in agreement with predictions from the model developed by Randrup [fr
Singlet-triplet splittings from the virial theorem and single-particle excitation energies
Becke, Axel D.
2018-01-01
The zeroth-order (uncorrelated) singlet-triplet energy difference in single-particle excited configurations is 2Kif, where Kif is the Coulomb self-energy of the product of the transition orbitals. Here we present a non-empirical, virial-theorem argument that the correlated singlet-triplet energy difference should be half of this, namely, Kif. This incredibly simple result gives vertical HOMO-LUMO excitation energies in small-molecule benchmarks as good as the popular TD-B3LYP time-dependent approach to excited states. For linear acenes and nonlinear polycyclic aromatic hydrocarbons, the performance is significantly better than TD-B3LYP. In addition to the virial theorem, the derivation borrows intuitive pair-density concepts from density-functional theory.
Effect of collision energy and vibrational excitation on endothermic ion-molecule reactions
International Nuclear Information System (INIS)
Turner, T.P.
1984-07-01
This thesis is divided into two major parts. In the first part an experimental study of proton and deuteron transfer in H 2 + + He and HD + + He has been carried out as a function of kinetic and vibrational energy. The data gives evidence that at lower kinetic energies, the spectator stripping mechanism indeed plays an important role when H 2 + or HD + is vibrationally excited. The second half of this thesis examines the relative efficiencies between the excitation of C-C stretching vibration and collision energy on the promotion of the H atom transfer reaction of C 2 H 2 + + H 2 → C 2 H 3 + + H
Probing shape coexistence in neutron-deficient $^{72}$Se via low-energy Coulomb excitation
We propose to study the evolution of nuclear structure in neutron-deficient $^{72}$Se by performing a low-energy Coulomb excitation measurement. Matrix elements will be determined for low-lying excited states allowing for a full comparison with theoretical predictions. Furthermore, the intrinsic shape of the ground state, and the second 0$^{+}$ state, will be investigated using the quadrupole sum rules method.
σ-SCF: A direct energy-targeting method to mean-field excited states
Ye, Hong-Zhou; Welborn, Matthew; Ricke, Nathan D.; Van Voorhis, Troy
2017-12-01
The mean-field solutions of electronic excited states are much less accessible than ground state (e.g., Hartree-Fock) solutions. Energy-based optimization methods for excited states, like Δ-SCF (self-consistent field), tend to fall into the lowest solution consistent with a given symmetry—a problem known as "variational collapse." In this work, we combine the ideas of direct energy-targeting and variance-based optimization in order to describe excited states at the mean-field level. The resulting method, σ-SCF, has several advantages. First, it allows one to target any desired excited state by specifying a single parameter: a guess of the energy of that state. It can therefore, in principle, find all excited states. Second, it avoids variational collapse by using a variance-based, unconstrained local minimization. As a consequence, all states—ground or excited—are treated on an equal footing. Third, it provides an alternate approach to locate Δ-SCF solutions that are otherwise hardly accessible by the usual non-aufbau configuration initial guess. We present results for this new method for small atoms (He, Be) and molecules (H2, HF). We find that σ-SCF is very effective at locating excited states, including individual, high energy excitations within a dense manifold of excited states. Like all single determinant methods, σ-SCF shows prominent spin-symmetry breaking for open shell states and our results suggest that this method could be further improved with spin projection.
Generating Excitement: Build Your Own Generator to Study the Transfer of Energy
Fletcher, Kurt; Rommel-Esham, Katie; Farthing, Dori; Sheldon, Amy
2011-01-01
The transfer of energy from one form to another can be difficult to understand. The electrical energy that turns on a lamp may come from the burning of coal, water falling at a hydroelectric plant, nuclear reactions, or gusts of wind caused by the uneven heating of the Earth. The authors have developed and tested an exciting hands-on activity to…
Augulis, Ramunas; Pugzlys, Audrius; Hurenkamp, Johannes; Feringa, Ben L.; van Esch, Jan H.; van Loosdrecht, Paul H. M.
2007-01-01
Energy transfer properties of novel coumarin-perylene bisimide dendrimer are studied by means of steady state and time-resolved UV/vis spectroscopy. At low donor excitation density fast (transfer rate similar to 10 ps(-1)) and efficient (quantum yield similar to 99.5%) donor-acceptor energy transfer
Excitation and dissociation of molecules by low-energy (0-15 eV) electrons
International Nuclear Information System (INIS)
Verhaart, G.J.
1980-01-01
The author deals with excitation and dissociation processes which result from the interaction between low-energy (0.15 eV) electrons and molecules. Low-energy electron-impact spectroscopy is used to gain a better knowledge of the electronic structure of halomethanes, ethylene and some of its halogen substituted derivatives, and some more complex organic molecules. (Auth.)
Excitation energy transfer from dye molecules to doped graphene
Indian Academy of Sciences (India)
Recently, we have reported theoretical studies on the rate of energy transfer ... Dirac cone approximation and hence our conclusions are of qualitative nature. 2. .... make another change of variable to r given by r = ki q/2 to get. G1 (q) = Aq2.
Raeber, Alexandra E; Wong, Bryan M
2015-05-12
We present a detailed analysis of several time-dependent DFT (TD-DFT) methods, including conventional hybrid functionals and two types of nonempirically tuned range-separated functionals, for predicting a diverse set of electronic excitations in DNA nucleobase monomers and dimers. This large and extensive set of excitations comprises a total of 50 different transitions (for each tested DFT functional) that includes several n → π and π → π* valence excitations, long-range charge-transfer excitations, and extended Rydberg transitions (complete with benchmark calculations from high-level EOM-CCSD(T) methods). The presence of localized valence excitations as well as extreme long-range charge-transfer excitations in these systems poses a serious challenge for TD-DFT methods that allows us to assess the importance of both short- and long-range exchange contributions for simultaneously predicting all of these various transitions. In particular, we find that functionals that do not have both short- and full long-range exchange components are unable to predict the different types of nucleobase excitations with the same accuracy. Most importantly, the current study highlights the importance of both short-range exchange and a nonempirically tuned contribution of long-range exchange for accurately predicting the diverse excitations in these challenging nucleobase systems.
Range and energy functions of interest in neutron dosimetry
International Nuclear Information System (INIS)
Bhatia, D.P.; Nagarajan, P.S.
1978-01-01
This report documents the energy and range functions generated and used in fast neutron interface dosimetry studies. The basic data of stopping power employed are the most recent. The present report covers a number of media mainly air, oxygen, nitrogen, polythene, graphite, bone and tissue, and a number of charged particles, namely protons, alphas, 9 Be, 11 B, 12 C, 13 C, 14 N and 16 O. These functions would be useful for generation of energy and range values for any of the above particles in any of the above media within +- 1% in any dosimetric calculations. (author)
Long-range interactions of excited He atoms with ground-state noble-gas atoms
Zhang, J.-Y.; Qian, Ying; Schwingenschlö gl, Udo; Yan, Z.-C.
2013-01-01
The dispersion coefficients C6, C8, and C10 for long-range interactions of He(n1,3S) and He(n1,3P), 2≤n≤10, with the ground-state noble-gas atoms Ne, Ar, Kr, and Xe are calculated by summing over the reduced matrix elements of multipole transition
Rury, Aaron S; Wiley, Theodore E; Sension, Roseanne J
2015-03-17
Porphyrins and the related chlorins and corrins contain a cyclic tetrapyrrole with the ability to coordinate an active metal center and to perform a variety of functions exploiting the oxidation state, reactivity, and axial ligation of the metal center. These compounds are used in optically activated applications ranging from light harvesting and energy conversion to medical therapeutics and photodynamic therapy to molecular electronics, spintronics, optoelectronic thin films, and optomagnetics. Cobalt containing corrin rings extend the range of applications through photolytic cleavage of a unique axial carbon-cobalt bond, permitting spatiotemporal control of drug delivery. The photochemistry and photophysics of cyclic tetrapyrroles are controlled by electronic relaxation dynamics including internal conversion and intersystem crossing. Typically the electronic excitation cascades through ring centered ππ* states, ligand to metal charge transfer (LMCT) states, metal to ligand charge transfer (MLCT) states, and metal centered states. Ultrafast transient absorption spectroscopy provides a powerful tool for the investigation of the electronic state dynamics in metal containing tetrapyrroles. The UV-visible spectrum is sensitive to the oxidation state, electronic configuration, spin state, and axial ligation of the central metal atom. Ultrashort broadband white light probes spanning the range from 270 to 800 nm, combined with tunable excitation pulses, permit the detailed unravelling of the time scales involved in the electronic energy cascade. State-of-the-art theoretical calculations provide additional insight required for precise assignment of the states. In this Account, we focus on recent ultrafast transient absorption studies of ferric porphyrins and corrin containing cob(III)alamins elucidating the electronic states responsible for ultrafast energy cascades, excited state dynamics, and the resulting photoreactivity or photostability of these compounds. Iron
Coherent excitation-energy transfer and quantum entanglement in a dimer
International Nuclear Information System (INIS)
Liao Jieqiao; Sun, C. P.; Huang Jinfeng; Kuang Leman
2010-01-01
We study coherent energy transfer of a single excitation and quantum entanglement in a dimer, which consists of a donor and an acceptor modeled by two two-level systems. Between the donor and the acceptor, there exists a dipole-dipole interaction, which provides the physical mechanism for coherent energy transfer and entanglement generation. The donor and the acceptor couple to two independent heat baths with diagonal couplings that do not dissipate the energy of the noncoupling dimer. Special attention is paid to the effect on single-excitation energy transfer and entanglement generation of the energy detuning between the donor and the acceptor and the temperatures of the two heat baths. It is found that, the probability for single-excitation energy transfer largely depends on the energy detuning in the low temperature limit. Concretely, the positive and negative energy detunings can increase and decrease the probability at steady state, respectively. In the high temperature limit, however, the effect of the energy detuning on the probability is negligibly small. We also find that the probability is negligibly dependent on the bath temperature difference of the two heat baths. In addition, it is found that quantum entanglement can be generated in the process of coherent energy transfer. As the bath temperature increases, the generated steady-state entanglement decreases. For a given bath temperature, the steady-state entanglement decreases with the increase of the absolute value of the energy detuning.
Fusion-fission of superheavy nuclei at low excitation energies
International Nuclear Information System (INIS)
Itkis, M.G.; Oganesyan, Yu.Ts.; Kozulin, E.M.
2000-01-01
The process of fusion-fission of superheavy nuclei with Z = 102 -122 formed in the reactions with 22 Ne, 26 Mg, 48 Ca, 58 Fe and 86 Kr ions at energies near and below the Coulomb barrier has been studied. The experiments were carried out at the U-400 accelerator of the Flerov Laboratory of Nuclear Reactions (JINR) using a time-of-flight spectrometer of fission fragments CORSET and a neutron multi-detector DEMON. As a result of the experiments, mass and energy distributions of fission fragments, fission and quasi-fission cross sections, multiplicities of neutrons and gamma-rays and their dependence on the mechanism of formation and decay of compound superheavy systems have been studied
International Nuclear Information System (INIS)
Artz, B.E.; Short, M.A.
1976-01-01
A comparison was made between the direct tube excitation mode and the secondary target excitation mode using a Kevex 0810 energy dispersive x-ray fluorescence system. Relative sensitivities and detection limits were determined with two system configurations. The first configuration used a standard, high power, x-ray fluorescence tube to directly excite the specimen. Several x-ray tubes, including chromium, molybdenum, and tungsten, both filtered and not filtered, were employed. The second configuration consisted of using the x-ray tube to excite a secondary target which in turn excited the specimen. Appropriate targets were compared to the direct excitation results. Relative sensitivities and detection limits were determined for K-series lines for elements from magnesium to barium contained in a low atomic number matrix and in a high atomic number matrix
Fang, Fei; Xia, Guanghui; Wang, Jianguo
2018-02-01
The nonlinear dynamics of cantilevered piezoelectric beams is investigated under simultaneous parametric and external excitations. The beam is composed of a substrate and two piezoelectric layers and assumed as an Euler-Bernoulli model with inextensible deformation. A nonlinear distributed parameter model of cantilevered piezoelectric energy harvesters is proposed using the generalized Hamilton's principle. The proposed model includes geometric and inertia nonlinearity, but neglects the material nonlinearity. Using the Galerkin decomposition method and harmonic balance method, analytical expressions of the frequency-response curves are presented when the first bending mode of the beam plays a dominant role. Using these expressions, we investigate the effects of the damping, load resistance, electromechanical coupling, and excitation amplitude on the frequency-response curves. We also study the difference between the nonlinear lumped-parameter and distributed-parameter model for predicting the performance of the energy harvesting system. Only in the case of parametric excitation, we demonstrate that the energy harvesting system has an initiation excitation threshold below which no energy can be harvested. We also illustrate that the damping and load resistance affect the initiation excitation threshold.
JANUS - A setup for low-energy Coulomb excitation at ReA3
Lunderberg, E.; Belarge, J.; Bender, P. C.; Bucher, B.; Cline, D.; Elman, B.; Gade, A.; Liddick, S. N.; Longfellow, B.; Prokop, C.; Weisshaar, D.; Wu, C. Y.
2018-03-01
A new experimental setup for low-energy Coulomb excitation experiments was constructed in a collaboration between the National Superconducting Cyclotron Laboratory (NSCL), Lawrence Livermore National Laboratory (LLNL), and the University of Rochester and was commissioned at the general purpose beam line of NSCL's ReA3 reaccelerator facility. The so-called JANUS setup combines γ-ray detection with the Segmented Ge Array (SeGA) and scattered particle detection using a pair of segmented double-sided Si detectors (Bambino 2). The low-energy Coulomb excitation program that JANUS enables will complement intermediate-energy Coulomb excitation studies that have long been performed at NSCL by providing access to observables that quantify collectivity beyond the first excited state, including the sign and magnitude of excited-state quadrupole moments. In this work, the setup and its performance will be described based on the commissioning run that used stable 78Kr impinging onto a 1.09 mg/cm2208Pb target at a beam energy of 3.9 MeV/u.
Energy principle for excitations in plasmas with counterstreaming electron flows
Kumar, Atul; Shukla, Chandrasekhar; Das, Amita; Kaw, Predhiman
2018-05-01
A relativistic electron beam propagating through plasma induces a return electron current in the system. Such a system of interpenetrating forward and return electron current is susceptible to a host of instabilities. The physics of such instabilities underlies the conversion of the flow kinetic energy to the electromagnetic field energy. Keeping this in view, an energy principle analysis has been enunciated in this paper. Such analyses have been widely utilized earlier in the context of conducting fluids described by MHD model [I. B. Bernstein et al., Proceedings of the Royal Society of London A: Mathematical, Physical and Engineering Sciences 244(1236), 17-40 (1958)]. Lately, such an approach has been employed for the electrostatic two stream instability for the electron beam plasma system [C. N. Lashmore-Davies, Physics of Plasmas 14(9), 092101 (2007)]. In contrast, it has been shown here that even purely growing mode like Weibel/current filamentation instability for the electron beam plasma system is amenable to such a treatment. The treatment provides an understanding of the energetics associated with the growing mode. The growth rate expression has also been obtained from it. Furthermore, it has been conclusively demonstrated in this paper that for identical values of S4=∑αn0 αv0α 2/n0γ0 α, the growth rate is higher when the counterstreaming beams are symmetric (i.e. S3 = ∑αn0αv 0α/n0γ0α = 0) compared to the case when the two beams are asymmetric (i.e. when S3 is finite). Here, v 0α, n0α and γ0α are the equilibrium velocity, electron density and the relativistic factor for the electron species `α' respectively and n0 = ∑αn0α is the total electron density. Particle - In - Cell simulations have been employed to show that the saturated amplitude of the field energy is also higher in the symmetric case.
Relativistic Energy Density Functionals: Exotic modes of excitation
International Nuclear Information System (INIS)
Vretenar, D.; Paar, N.; Marketin, T.
2008-01-01
The framework of relativistic energy density functionals has been applied to the description of a variety of nuclear structure phenomena, not only in spherical and deformed nuclei along the valley of β-stability, but also in exotic systems with extreme isospin values and close to the particle drip-lines. Dynamical aspects of exotic nuclear structure have been investigated with the relativistic quasiparticle random-phase approximation. We present results for the evolution of low-lying dipole (pygmy) strength in neutron-rich nuclei, and charged-current neutrino-nucleus cross sections.
Energy Technology Data Exchange (ETDEWEB)
Zhang Lei; Kashiwakura, Shunsuke; Wagatsuma, Kazuaki, E-mail: wagatuma@imr.tohoku.ac.jp
2012-01-15
A Boltzmann plot for many iron ionic lines having excitation energies of 4.7-9.1 eV was investigated in an argon glow discharge plasma when the discharge parameters, such as the voltage/current and the gas pressure, were varied. A Grimm-style radiation source was employed in a DC voltage range of 400-800 V at argon pressures of 400-930 Pa. The plot did not follow a linear relationship over a wide range of the excitation energy, but it yielded a normal Boltzmann distribution in the range of 4.7-5.8 eV and a large overpopulation in higher-lying excitation levels of iron ion. A probable reason for this phenomenon is that excitations for higher excited energy levels of iron ion would be predominantly caused by non-thermal collisions with argon species, the internal energy of which is received by iron atoms for the ionization. Particular intense ionic lines, which gave a maximum peak of the Boltzmann plot, were observed at an excitation energy of ca. 7.7 eV. They were the Fe II 257.297-nm and the Fe II 258.111-nm lines, derived from the 3d{sup 5}4s4p {sup 6}P excited levels. The 3d{sup 5}4s4p {sup 6}P excited levels can be highly populated through a resonance charge transfer from the ground state of argon ion, because of good matching in the excitation energy as well as the conservation of the total spin before and after the collision. An enhancement factor of the emission intensity for various Fe II lines could be obtained from a deviation from the normal Boltzmann plot, which comprised the emission lines of 4.7-5.8 eV. It would roughly correspond to a contribution of the charge transfer excitation to the excited levels of iron ion, suggesting that the charge-transfer collision could elevate the number density of the corresponding excited levels by a factor of ca.10{sup 4}. The Boltzmann plots give important information on the reason why a variety of iron ionic lines can be emitted from glow discharge plasmas.
Körzdörfer, Thomas
2014-11-18
Density functional theory (DFT) and its time-dependent extension (TD-DFT) are powerful tools enabling the theoretical prediction of the ground- and excited-state properties of organic electronic materials with reasonable accuracy at affordable computational costs. Due to their excellent accuracy-to-numerical-costs ratio, semilocal and global hybrid functionals such as B3LYP have become the workhorse for geometry optimizations and the prediction of vibrational spectra in modern theoretical organic chemistry. Despite the overwhelming success of these out-of-the-box functionals for such applications, the computational treatment of electronic and structural properties that are of particular interest in organic electronic materials sometimes reveals severe and qualitative failures of such functionals. Important examples include the overestimation of conjugation, torsional barriers, and electronic coupling as well as the underestimation of bond-length alternations or excited-state energies in low-band-gap polymers.In this Account, we highlight how these failures can be traced back to the delocalization error inherent to semilocal and global hybrid functionals, which leads to the spurious delocalization of electron densities and an overestimation of conjugation. The delocalization error for systems and functionals of interest can be quantified by allowing for fractional occupation of the highest occupied molecular orbital. It can be minimized by using long-range corrected hybrid functionals and a nonempirical tuning procedure for the range-separation parameter.We then review the benefits and drawbacks of using tuned long-range corrected hybrid functionals for the description of the ground and excited states of π-conjugated systems. In particular, we show that this approach provides for robust and efficient means of characterizing the electronic couplings in organic mixed-valence systems, for the calculation of accurate torsional barriers at the polymer limit, and for the
Multicomponent Time-Dependent Density Functional Theory: Proton and Electron Excitation Energies.
Yang, Yang; Culpitt, Tanner; Hammes-Schiffer, Sharon
2018-04-05
The quantum mechanical treatment of both electrons and protons in the calculation of excited state properties is critical for describing nonadiabatic processes such as photoinduced proton-coupled electron transfer. Multicomponent density functional theory enables the consistent quantum mechanical treatment of more than one type of particle and has been implemented previously for studying ground state molecular properties within the nuclear-electronic orbital (NEO) framework, where all electrons and specified protons are treated quantum mechanically. To enable the study of excited state molecular properties, herein the linear response multicomponent time-dependent density functional theory (TDDFT) is derived and implemented within the NEO framework. Initial applications to FHF - and HCN illustrate that NEO-TDDFT provides accurate proton and electron excitation energies within a single calculation. As its computational cost is similar to that of conventional electronic TDDFT, the NEO-TDDFT approach is promising for diverse applications, particularly nonadiabatic proton transfer reactions, which may exhibit mixed electron-proton vibronic excitations.
Farooq, Shazia; Chmeliov, Jevgenij; Trinkunas, Gediminas; Valkunas, Leonas; van Amerongen, Herbert
2016-04-07
We have compared picosecond fluorescence decay kinetics for stacked and unstacked photosystem II membranes in order to evaluate the efficiency of excitation energy transfer between the neighboring layers. The measured kinetics were analyzed in terms of a recently developed fluctuating antenna model that provides information about the dimensionality of the studied system. Independently of the stacking state, all preparations exhibited virtually the same value of the apparent dimensionality, d = 1.6. Thus, we conclude that membrane stacking does not affect the efficiency of the delivery of excitation energy toward the reaction centers but ensures a more compact organization of the thylakoid membranes within the chloroplast and separation of photosystems I and II.
Luminescence of YbP3O9 upon excitation in the UV-VUV range
International Nuclear Information System (INIS)
Stryganyuk, G; Trots, D; Berezovskaya, I; Shalapska, T; Voloshinovskii, A; Dotsenko, V; Zimmerer, G
2007-01-01
X-ray powder diffraction and luminescence spectral-kinetic studies have been performed for ytterbium metaphosphate (YbP 3 O 9 ) in the 12-290 K temperature range. The diffraction investigation has shown YbP 3 O 9 to be of monoclinic P 2 1 /c structure at T = 12-290 K. Charge transfer luminescence originating from Yb 3+ ion has been revealed. The carrier confinement within the Yb 3+ charge transfer state is pronounced at T = 12 K. A tendency has been revealed for charge carriers in YbP 3 O 9 to be localized in a trapped exciton state at room temperature. The quenching mechanisms for Yb 3+ charge transfer luminescence and processes competing with the formation of the Yb 3+ charge transfer state are discussed
Bose, Samik; Chakrabarty, Suman; Ghosh, Debashree
2016-05-19
Hybrid quantum mechanics/molecular mechanics (QM/MM) is applied to the fluorinated green fluorescent protein (GFP) chromophore (DFHBDI) in its deprotonated form to understand the solvatochromic shifts in its vertical detachment energy (VDE) and vertical excitation energy (VEE). This variant of the GFP chromophore becomes fluorescent in an RNA environment and has a wide range of applications in biomedical and biochemical fields. From microsolvation studies, we benchmark (with respect to full QM) the accuracy of our QM/MM calculations with effective fragment potential (EFP) as the MM method of choice. We show that while the solvatochromic shift in the VEE is minimal (0.1 eV blue shift) and its polarization component is only 0.03 eV, the effect of the solvent on the VDE is quite large (3.85 eV). We also show by accurate calculations on the solvatochromic shift of the VDE that polarization accounts for ∼0.23 eV and therefore cannot be neglected. The effect of the counterions on the VDE of the deprotonated chromophore in solvation is studied in detail, and a charge-smearing scheme is suggested for charged chromophores.
High spin spectroscopy near the N=Z line: Channel selection and excitation energy systematics
Energy Technology Data Exchange (ETDEWEB)
Svensson, C.E.; Cameron, J.A.; Flibotte, S. [McMaster Univ., Ontario (Canada)] [and others
1996-12-31
The total {gamma}-ray and charged-particle energies emitted in fusion-evaporation reactions leading to N=Z compound systems in the A = 50-70 mass region have been measured with the 8{pi} {gamma}-ray spectrometer and the miniball charged-particle detector array. A new method of channel selection has been developed which combines particle identification with these total energy measurements and greatly improves upon the selectivity possible with particle detection alone. In addition, the event by event measurement of total {gamma}-ray energies using the BGO ball of the 8{pi} spectrometer has allowed a determination of excitation energies following particle evaporation for a large number of channels in several different reactions. The new channel selection procedure and excitation energy systematics are illustrated with data from the reaction of {sup 24}Mg on {sup 40}Ca at E{sub lab} = 80MeV.
Anda, André; De Vico, Luca; Hansen, Thorsten
2017-06-08
Light-harvesting system 2 (LH2) executes the primary processes of photosynthesis in purple bacteria; photon absorption, and energy transportation to the reaction center. A detailed mechanistic insight into these operations is obscured by the complexity of the light-harvesting systems, particularly by the chromophore-environment interaction. In this work, we focus on the effects of the protein residues that are ligated to the bacteriochlorophylls (BChls) and construct potential energy surfaces of the ground and first optically excited state for the various BChl-residue systems where we in each case consider two degrees of freedom in the intermolecular region. We find that the excitation energies are only slightly affected by the considered modes. In addition, we see that axial ligands and hydrogen-bonded residues have opposite effects on both excitation energies and oscillator strengths by comparing to the isolated BChls. Our results indicate that only a small part of the chromophore-environment interaction can be associated with the intermolecular region between a BChl and an adjacent residue, but that it may be possible to selectively raise or lower the excitation energy at the axial and planar residue positions, respectively.
International Nuclear Information System (INIS)
Lisitsyn, V.M.; Grechkina, T. V.; Korepanov, V.I.; Lisitsyna, L.A.
2004-01-01
Full text: In this paper we present results of comparison of efficiency creations of primary defects in crystals of fluorides of two different lattice structures: stone salt - LiF and rutile MgF 2 . We have used the methods with nanosecond time-resolved of pulse spectroscopy and found laws of creation and evolution self-trapped exciton (STE) and the F centers in a temperature range from 12.5 to 500 K and a time interval from 10 -8 to 10 -1 s after the ending of influence of a pulse electron. The density of excitation of crystals in a pulse is no more than 0.1 J·cm -3 , average energy electrons made 200 keV, duration electron pulse - 7 ns. It is established, that in crystal LiF under action of radiation are created STE two types which have various spectral-kinetic parameters absorption and emission transitions, various values of activation energy of processes of a post-industrial relaxation and different character of temperature dependences of creation efficiency under action electron pulse. In the field of low temperatures (12.5 K) created on center STE has absorption bands on 5.5 and 5.1 eV and emission band on 5.8 eV. Off-center STE has absorption on 5.3 and 4.75 eV and emission on 4.4 eV bands and are created in the interval 12.5-170 K with peak efficiency h area 60 K. In crystal MgF 2 at low temperatures (20 K) under action of radiation one STE with a nucleus occupying off-center configuration, having luminescence band on 3.2 eV and a series absorption transitions in area 4-5.5 eV is created. Concurrently with STE in both crystals under action of a pulse electron the F-centers with efficiency, not dependent on temperature of a crystal in area 20-100 K are created. There are two alternative processes under action of an irradiation with growth of temperature higher 100 K: reducing of STE creation and increasing of F centers creation. In both crystals quenching temperature of luminescence STE at T>60 K which is not accompanied by growth of efficiency of creation
Identification of an isomer in 110Ag at 1-keV excitation energy
International Nuclear Information System (INIS)
Clark, D.D.; Kostroun, V.O.; Siems, N.E.
1975-01-01
The existence of a new isomeric state in 110 Ag at approx. 1 keV excitation has been established in two experiments using a new instrument, the inner-shell-vacancy (ISV) detector. In the first experiment, a transition with a half-life of 660 plus-or-minus 40 ns was observed to follow the well-known 116-keV M4 transition that depopulates the 6 + 250-day isomeric level in 110 Ag; the energy of the new transition was deduced to be 109 Ag(n, γ) 110 Ag reaction to follow γ transitions previously assigned by others to populate a 1-keV excited state. The two results indicate the existence of a 2 - 660-ns isomer at 1.11 keV. Under the assumption that the newly observed transition is from a 2 - 1.11-keV state to the 1 + ground state, its hindrance factor with respect to the Moszkowski estimate is approx. 2.6 times 10 3 . Possible chemical-state perturbations of the measured half-life are estimated to be much smaller than the measurement error. In both experiments the approx. 1-keV transition was detected with the ISV detector, a new device based on the well-established atomic effect that within approx. 10 -14 s after the formation of an inner shell vacancy an atom will undergo a multiple loss of []lectrons ranging from several to 20 or more, the number being a function of Z and subshell. The emitted electrons, which are very soft, are collected with an accelerating and focusing electrostatic lens and detected with a plastic scintillator and a photomultiplier tube. Nuclear transitions that cause ISVs can thus be sensed. Experiments are described that show the detector is fast, sensitive, selective, and efficient in responding to ISVs.
Renewable Energy Opportunities at White Sands Missile Range, New Mexico
Energy Technology Data Exchange (ETDEWEB)
Chvala, William D.; Solana, Amy E.; States, Jennifer C.; Warwick, William M.; Weimar, Mark R.; Dixon, Douglas R.
2008-09-01
The document provides an overview of renewable resource potential at White Sands Missile Range (WSMR) based primarily upon analysis of secondary data sources supplemented with limited on-site evaluations. The effort was funded by the U.S. Army Installation Management Command (IMCOM) as follow-on to the 2005 DoD Renewable Energy Assessment. This effort focuses on grid-connected generation of electricity from renewable energy sources and also ground source heat pumps (GSHPs) for heating and cooling buildings, as directed by IMCOM.
Energy conservation attenuates the loss of skeletal muscle excitability during intense contractions
DEFF Research Database (Denmark)
Macdonald, W A; Ørtenblad, N; Nielsen, Ole Bækgaard
2007-01-01
High-frequency stimulation of skeletal muscle has long been associated with ionic perturbations, resulting in the loss of membrane excitability, which may prevent action potential propagation and result in skeletal muscle fatigue. Associated with intense skeletal muscle contractions are large...... with control muscles, the resting metabolites ATP, phosphocreatine, creatine, and lactate, as well as the resting muscle excitability as measured by M-waves, were unaffected by treatment with BTS plus dantrolene. Following 20 or 30 s of continuous 60-Hz stimulation, BTS-plus-dantrolene-treated muscles showed...... changes in muscle metabolites. However, the role of metabolites in the loss of muscle excitability is not clear. The metabolic state of isolated rat extensor digitorum longus muscles at 30 degrees C was manipulated by decreasing energy expenditure and thereby allowed investigation of the effects of energy...
Time-resolved stimulated emission depletion and energy transfer dynamics in two-photon excited EGFP
Masters, T. A.; Robinson, N. A.; Marsh, R. J.; Blacker, T. S.; Armoogum, D. A.; Larijani, B.; Bain, A. J.
2018-04-01
Time and polarization-resolved stimulated emission depletion (STED) measurements are used to investigate excited state evolution following the two-photon excitation of enhanced green fluorescent protein (EGFP). We employ a new approach for the accurate STED measurement of the hitherto unmeasured degree of hexadecapolar transition dipole moment alignment ⟨α40 ⟩ present at a given excitation-depletion (pump-dump) pulse separation. Time-resolved polarized fluorescence measurements as a function of pump-dump delay reveal the time evolution of ⟨α40 ⟩ to be considerably more rapid than predicted for isotropic rotational diffusion in EGFP. Additional depolarization by homo-Förster resonance energy transfer is investigated for both ⟨α20 ⟩ (quadrupolar) and ⟨α40 ⟩ transition dipole alignments. These results point to the utility of higher order dipole correlation measurements in the investigation of resonance energy transfer processes.
International Nuclear Information System (INIS)
Ostafin, A.E.; Lipsky, S.
1993-01-01
Fluorescence action spectra have been obtained for the neat liquids, cis-decalin, trans-decalin, bicyclohexyl, cyclohexane, methylcyclohexane, isobutylcyclohexane, 2,3,4-trimethylpentane, 2,3-dimethylbutane, 3-methylhexane, 3-methylpentane, n-decane, n-dodecane, and n-pentadecane at excitation energies, ε, ranging from their absorption onsets (at ca. 7 eV) to 10.3 eV. For all compounds, with the exception of cis-decalin, the fluorescence quantum yield is observed to monotonically decline with increasing ε, reaching a minimum value at an energy, ε m (a few tenths of an eV above the liquid phase ionization threshold, ε l ) followed by a slow increase. In the case of cis-decalin, the fluorescence quantum yield remains constant over the entire range of excitation energies studied, permitting its use as a quantum counter replacing the standard sodium salicylate, at least over a spectral range from 185 to 120 nm. The recovery of the fluorescence quantum yield for ε>ε m is attributed to an increasing probability for electron ejection followed by e - +RH + geminate recombination, to produce an excited state of RH with energy less than ε l . From a simple analysis of the action spectrum, a lower bound estimate of the electron ejection probability, φ ± , is obtained as a function of ε. In the case of cyclohexane, where φ ± has been obtained by other techniques at ε congruent 10 eV, the lower bound estimate agrees with the experimental value. From this agreement, arguments are presented to make plausible the conjecture that in all these liquids, the initially produced e - +RH + geminate ion pair first rapidly internally converts to an ion-pair state ca
Energy-range relation and mean energy variation in therapeutic particle beams
International Nuclear Information System (INIS)
Kempe, Johanna; Brahme, Anders
2008-01-01
Analytical expressions for the mean energy and range of therapeutic light ion beams and low- and high-energy electrons have been derived, based on the energy dependence of their respective stopping powers. The new mean energy and range relations are power-law expressions relevant for light ion radiation therapy, and are based on measured practical ranges or known tabulated stopping powers and ranges for the relevant incident particle energies. A practical extrapolated range, R p , for light ions was defined, similar to that of electrons, which is very closely related to the extrapolated range of the primary ions. A universal energy-range relation for light ions and electrons that is valid for all material mixtures and compounds has been developed. The new relation can be expressed in terms of the range for protons and alpha particles, and is found to agree closely with experimental data in low atomic number media and when the difference in the mean ionization energy is low. The variation of the mean energy with depth and the new energy-range relation are useful for accurate stopping power and mass scattering power calculations, as well as for general particle transport and dosimetry applications
Estimation of excitation forces for wave energy converters control using pressure measurements
Abdelkhalik, O.; Zou, S.; Robinett, R.; Bacelli, G.; Wilson, D.
2017-08-01
Most control algorithms of wave energy converters require prediction of wave elevation or excitation force for a short future horizon, to compute the control in an optimal sense. This paper presents an approach that requires the estimation of the excitation force and its derivatives at present time with no need for prediction. An extended Kalman filter is implemented to estimate the excitation force. The measurements in this approach are selected to be the pressures at discrete points on the buoy surface, in addition to the buoy heave position. The pressures on the buoy surface are more directly related to the excitation force on the buoy as opposed to wave elevation in front of the buoy. These pressure measurements are also more accurate and easier to obtain. A singular arc control is implemented to compute the steady-state control using the estimated excitation force. The estimated excitation force is expressed in the Laplace domain and substituted in the control, before the latter is transformed to the time domain. Numerical simulations are presented for a Bretschneider wave case study.
Energy Technology Data Exchange (ETDEWEB)
Kumagai, Tsutaru, E-mail: kumagai.t.af@m.titech.ac.jp; Kishi, Tetsuo; Yano, Tetsuji [Department of Chemistry and Materials Science, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8550 (Japan)
2015-03-21
Bubble-containing Nd{sup 3+}-doped tellurite glass microspheres were fabricated by localized laser heating technique to investigate their optical properties for use as microresonators. Fluorescence and excitation spectra measurements were performed by pumping with a tunable CW-Ti:Sapphire laser. The excitation spectra manifested several sharp peaks due to the conventional whispering gallery mode (WGM) when the pumping laser was irradiated to the edge part of the microsphere. However, when the excitation light was irradiated on the bubble position inside the microsphere, “non-WGM excitation” was induced, giving rise to numerous peaks at a broad wavelength range in the excitation spectra. Thus, efficient excitation was achieved over a wide wavelength range. Lasing threshold excited at the bubble position was much lower than that for the excitation at the edges of the microsphere. The lowest value of the laser threshold was 34 μW for a 4 μm sphere containing a 0.5 μm bubble. Efficiency of the excitation at the bubble position with broadband light was calculated to be 5 times higher than that for the edge of the microsphere. The bubble-containing microsphere enables efficient utilization of broadband light excitation from light-emitting diodes and solar light.
Radiative transport and collisional transfer of excitation energy in Cs vapors mixed with Ar or He
International Nuclear Information System (INIS)
Vadla, Cedomil; Horvatic, Vlasta; Niemax, Kay
2003-01-01
This paper is a review (with a few original additions) on the radiative transport and collisional transfer of energy in laser-excited cesium vapors in the presence of argon or helium. Narrow-band excitation of lines with Lorentz, Doppler and Voigt profiles is studied in order to calculate effective rates for pumping of spectral lines with profiles comprising inhomogeneous broadening components. The radiative transport of excitation energy is considered, and a new, simple and robust, but accurate theoretical method for quantitative treatment of radiation trapping in relatively optically thin media is presented. Furthermore, comprehensive lists of experimental values for the excitation energy transfer cross-sections related to thermal collisions in Cs-Ar and Cs-He mixtures are given. Within the collected cross-section data sets, specific regularities with respect to the energy defect, as well as the temperature, are discerned. A particular emphasis is put on the radiative and collisional processes important for the optimization of resonance-fluorescence imaging atomic filters based on Cs-noble gas systems
Two types of charge transfer excitations in low dimensional cuprates: an electron energy-loss study
Czech Academy of Sciences Publication Activity Database
Knupfer, M.; Fink, J.; Drechsler, S.-L.; Hayn, R.; Málek, Jiří; Moskvin, A.S.
137-140, - (2004), s. 469-473 ISSN 0368-2048 Institutional research plan: CEZ:AV0Z1010914 Keywords : cuprates * electronic excitations * electron energy-loss spectroscopy Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.069, year: 2004
Energy Technology Data Exchange (ETDEWEB)
Buta, A.M.; Steckmeyer, J.C. [Caen Univ., 14 (France). Lab. de Physique Corpusculaire; Auger, G. [Grand Accelerateur National d' Ions Lourds (GANIL), 14 - Caen (France)] [and others
2002-03-01
The excitation energy of the quasi-projectiles produced in heavy-ion collisions is determined for the {sup 58}Ni+{sup 197}Au reactions at 52 and 90 AMeV. A new method is proposed for isolating unambiguously the particles evaporated by the source. It consists in observing them at small angles along the flight direction of the source. (authors)
Interqubit coupling mediated by a high-excitation-energy quantum object
Ashhab, S.; Niskanen, A.O.; Harrabi, K.; Nakamura, Y.; Picot, T.; De Groot, P.C.; Harmans, C.J.P.M.; Mooij, J.E.; Nori, F.
2008-01-01
We consider a system composed of two qubits and a high excitation energy quantum object used to mediate coupling between the qubits. We treat the entire system quantum mechanically and analyze the properties of the eigenvalues and eigenstates of the total Hamiltonian. After reproducing well known
Energy Technology Data Exchange (ETDEWEB)
Schultz, D.R.; Krstic, P.S. [Oak Ridge National Lab. TN (United States). Physics Div.
1997-01-01
Due to the present interest in modeling and diagnosing the edge and divertor plasma regions in magnetically confined fusion devices, we have sought to provide new calculations regarding the elastic, excitation, ionization, and charge transfer cross sections in collisions among relevant ions, neutrals, and isotopes in the low-to intermediate-energy regime. We summarize here some of our recent work. (author)
Convergence of environment polarization effects in multiscale modeling of excitation energies
DEFF Research Database (Denmark)
Beerepoot, Maarten; Steindal, Arnfinn Hykkerud; Ruud, Kenneth
2014-01-01
We present a systematic investigation of the influence of polarization effects from a surrounding medium on the excitation energies of a chromophore. We use a combined molecular dynamics and polarizable embedding time-dependent density functional theory (PE-TD-DFT) approach for chromophores in pr...
International Nuclear Information System (INIS)
Peng, Degao; Yang, Yang; Zhang, Peng; Yang, Weitao
2014-01-01
In this article, we develop systematically second random phase approximations (RPA) and Tamm-Dancoff approximations (TDA) of particle-hole and particle-particle channels for calculating molecular excitation energies. The second particle-hole RPA/TDA can capture double excitations missed by the particle-hole RPA/TDA and time-dependent density-functional theory (TDDFT), while the second particle-particle RPA/TDA recovers non-highest-occupied-molecular-orbital excitations missed by the particle-particle RPA/TDA. With proper orbital restrictions, these restricted second RPAs and TDAs have a formal scaling of only O(N 4 ). The restricted versions of second RPAs and TDAs are tested with various small molecules to show some positive results. Data suggest that the restricted second particle-hole TDA (r2ph-TDA) has the best overall performance with a correlation coefficient similar to TDDFT, but with a larger negative bias. The negative bias of the r2ph-TDA may be induced by the unaccounted ground state correlation energy to be investigated further. Overall, the r2ph-TDA is recommended to study systems with both single and some low-lying double excitations with a moderate accuracy. Some expressions on excited state property evaluations, such as 〈S ^2 〉 are also developed and tested
Energy Technology Data Exchange (ETDEWEB)
Peng, Degao; Yang, Yang; Zhang, Peng [Department of Chemistry, Duke University, Durham, North Carolina 27708 (United States); Yang, Weitao, E-mail: weitao.yang@duke.edu [Department of Chemistry and Department of Physics, Duke University, Durham, North Carolina 27708 (United States)
2014-12-07
In this article, we develop systematically second random phase approximations (RPA) and Tamm-Dancoff approximations (TDA) of particle-hole and particle-particle channels for calculating molecular excitation energies. The second particle-hole RPA/TDA can capture double excitations missed by the particle-hole RPA/TDA and time-dependent density-functional theory (TDDFT), while the second particle-particle RPA/TDA recovers non-highest-occupied-molecular-orbital excitations missed by the particle-particle RPA/TDA. With proper orbital restrictions, these restricted second RPAs and TDAs have a formal scaling of only O(N{sup 4}). The restricted versions of second RPAs and TDAs are tested with various small molecules to show some positive results. Data suggest that the restricted second particle-hole TDA (r2ph-TDA) has the best overall performance with a correlation coefficient similar to TDDFT, but with a larger negative bias. The negative bias of the r2ph-TDA may be induced by the unaccounted ground state correlation energy to be investigated further. Overall, the r2ph-TDA is recommended to study systems with both single and some low-lying double excitations with a moderate accuracy. Some expressions on excited state property evaluations, such as 〈S{sup ^2}〉 are also developed and tested.
Carbon and energy balances for a range of biofuels options
Energy Technology Data Exchange (ETDEWEB)
Elsayed, M.A.; Matthews, R.; Mortimer, N.D.
2003-03-01
This is the final report of a project to produce a set of baseline energy and carbon balances for a range of electricity, heat and transport fuel production systems based on biomass feedstocks. A list of 18 important biofuel technologies in the UK was selected for study of their energy and carbon balances in a consistent approach. Existing studies on these biofuel options were reviewed and their main features identified in terms of energy input, greenhouse gas emissions (carbon dioxide, methane, nitrous oxide and total), transparency and relevance. Flow charts were produced to represent the key stages of the production of biomass and its conversion to biofuels. Outputs from the study included primary energy input per delivered energy output, carbon dioxide outputs per delivered energy output, methane output per delivered energy output, nitrous oxide output per delivered energy output and total greenhouse gas requirements. The net calorific value of the biofuel is given where relevant. Biofuels studied included: biodiesel from oilseed rape and recycled vegetable oil; combined heat and power (CHP) by combustion of wood chip from forestry residues; CHP by gasification of wood chip from short rotation coppice; electricity from the combustion of miscanthus, straw, wood chip from forestry residues and wood chip from short rotation coppice; electricity from gasification of wood chip from forestry residues and wood chip from short rotation coppice; electricity by pyrolysis of wood chip from forestry residues and wood chip from short rotation coppice; ethanol from lignocellulosics, sugar beet and wheat; heat (small scale) from combustion of wood chip from forestry residues and wood chip from short rotation coppice; and rapeseed oil from oilseed rape.
International Nuclear Information System (INIS)
Kumar, Rajiv; Sharma, Shagun; Singh, Pradeep; Kharab, Rajesh
2016-01-01
The energy-independent touching spheres schemes commonly used for the determination of the safe minimum value of the impact parameter for Coulomb excitation experiments are modified through the inclusion of an energy-dependent term. The touching spheres+3fm scheme after modification emerges out to be the best one while touching spheres+4fm scheme is found to be better in its unmodified form. (orig.)
Theoretical photoionization spectra in the UV photon energy range for a Mg-like Al+ ion
International Nuclear Information System (INIS)
Kim, Dae-Soung; Kim, Young Soon
2008-01-01
In the present work, we report the photoionization cross sections of the Al + ion calculated for the photon energy range 20-26 eV and 30-50 eV. We have expanded our previous calculation (2007 J. Phys. Soc. Japan 76 014302) with an optimized admixture of the initial ground state 3s 21 S and exited states 3s3p 1,3 P, 3s3d 1,3 D and 3s4s 1,3 S, and obtained significantly improved predictions for the main background and autoionizing resonance structures of the reported experimental spectra. The absolute measurements of the photoionization cross sections of the Al + ion in these energy ranges have been performed by West et al (2001 Phys. Rev. A 63 052719), and they reported that the prominent peaks around 21 eV were attributed to the effects of the significant influence of the small fraction of the fourth-order radiation with energies around 84 eV from the synchrotron source. In our previous work, the main shape for these cross sections was calculated assuming an admixture of initial 3s 21 S and 3s3p 3 P states, only with a rough overall estimate for the experimental spectra in the photon energy range 20-26 eV, and without these peaks around 21 eV. The report of the experimental assignment attributes these peaks to the excitation of a 2p electron from the core. However, our present results with the new admixture reveal similar peaks without considering the possibility of the core excitation
X-ray yields by low energy heavy ion excitation in alkali halide solid targets
International Nuclear Information System (INIS)
Kurup, M.B.; Prasad, K.G.; Sharma, R.P.
1981-01-01
Solid targets of the alkali halides KCl, NaCl and KBr are bombarded with ion beams of 35 Cl + , 40 Ar + and 63 Cu + in the energy range 165 keV to 320 keV. The MO and characteristic K X-ray yields resulting from the ion-atom collision have been systematically studied. Both MO and Cl K X-ray yields are enhanced by factors 3.5 and 2 respectively in KCl targets as compared to that in NaCl when bombarded with either Cl + or Ar + projectiles. An intercomparison of MO and K X-ray yields for a given projectile-target combination has shown that the latter increases ten times faster than the former as the energy of the projectile is increased from 165 to 320 keV indicating a correspondingly stronger velocity dependence of the K X-ray production process. The X-ray yields observed in the symmetric Cl-Cl collision are identical to those observed in the asymmetric Ar-Cl collision for the same projectile velocities in both KCl and NaCl targets. It is inferred that the multiple ionization of the projectile resulting in an increase in the binding energy of its inner shells offsets the expected enhancement in the X-ray yields in a symmetric collision. The same projectiles, Ar or Cl, incident on KBr targets have produced only Br L X-rays. Using substantially heavier projectiles than the target atoms (Na, K and Cl), like 63 Cu + ions, the inner shell excitation by recoiling atoms is shown. (orig.)
International Nuclear Information System (INIS)
Wilson, A.N.; Singh, A.K.; Huebel, H.; Rossbach, D.; Schonwasser, G.; Davidson, P.M.; Dracoulis, G.D.; Lane, G.J.; Goergen, A.; Korichi, A.; Hannachi, F.; Lopez-Martens, A.; Astier, A.; Azaiez, F.; Bourgeois, C.; Bazzacco, D.; Kroell, T.; Rossi-Alvarez, C.; Buforn, N.; Redon, N.
2005-01-01
The excitation energy of the lowest-energy superdeformed band in 196 Pb is established using the techniques of time-correlated γ-ray spectroscopy. Together with previous measurements on 192 Pb and 194 Pb, this result allows superdeformed excitation energies, binding energies, and two-proton and two-neutron separation energies to be studied systematically, providing stringent tests for current nuclear models. The results are examined for evidence of a 'superdeformed shell gap'
A new recoil distance technique using low energy coulomb excitation in inverse kinematics
Energy Technology Data Exchange (ETDEWEB)
Rother, W., E-mail: wolfram.rother@googlemail.com [Institut fuer Kernphysik der Universitaet zu Koeln, Zuelpicher Str. 77, D-50937 Koeln (Germany); Dewald, A.; Pascovici, G.; Fransen, C.; Friessner, G.; Hackstein, M. [Institut fuer Kernphysik der Universitaet zu Koeln, Zuelpicher Str. 77, D-50937 Koeln (Germany); Ilie, G. [Wright Nuclear Structure Laboratory, Yale University, New Haven, CT 06520 (United States); National Institute of Physics and Nuclear Engineering, P.O. Box MG-6, Bucharest-Magurele (Romania); Iwasaki, H. [National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, MI 48824 (United States); Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824 (United States); Jolie, J. [Institut fuer Kernphysik der Universitaet zu Koeln, Zuelpicher Str. 77, D-50937 Koeln (Germany); Melon, B. [Dipartimento di Fisica, Universita di Firenze and INFN Sezione di Firenze, Sesto Fiorentino (Firenze) I-50019 (Italy); Petkov, P. [Institut fuer Kernphysik der Universitaet zu Koeln, Zuelpicher Str. 77, D-50937 Koeln (Germany); INRNE-BAS, Sofia (Bulgaria); Pfeiffer, M. [Institut fuer Kernphysik der Universitaet zu Koeln, Zuelpicher Str. 77, D-50937 Koeln (Germany); Pissulla, Th. [Institut fuer Kernphysik der Universitaet zu Koeln, Zuelpicher Str. 77, D-50937 Koeln (Germany); Bundesumweltministerium, Robert-Schuman-Platz 3, D - 53175 Bonn (Germany); Zell, K.-O. [Institut fuer Kernphysik der Universitaet zu Koeln, Zuelpicher Str. 77, D-50937 Koeln (Germany); Jakobsson, U.; Julin, R.; Jones, P.; Ketelhut, S.; Nieminen, P.; Peura, P. [Department of Physics, University of Jyvaeskylae, P.O. Box 35, FI-40014 (Finland); and others
2011-10-21
We report on the first experiment combining the Recoil Distance Doppler Shift technique and multistep Coulomb excitation in inverse kinematics at beam energies of 3-10 A MeV. The setup involves a standard plunger device equipped with a degrader foil instead of the normally used stopper foil. An array of particle detectors is positioned at forward angles to detect target-like recoil nuclei which are used as a trigger to discriminate against excitations in the degrader foil. The method has been successfully applied to measure lifetimes in {sup 128}Xe and is suited to be a useful tool for experiments with radioactive ion beams.
Energies and damping rates of elementary excitations in spin-1 Bose-Einstein-condensed gases
International Nuclear Information System (INIS)
Szirmai, Gergely; Szepfalusy, Peter; Kis-Szabo, Krisztian
2003-01-01
The finite temperature Green's function technique is used to calculate the energies and damping rates of the elementary excitations of homogeneous, dilute, spin-1 Bose gases below the Bose-Einstein condensation temperature in both the density and spin channels. For this purpose a self-consistent dynamical Hartree-Fock model is formulated, which takes into account the direct and exchange processes on equal footing by summing up certain classes of Feynman diagrams. The model is shown to satisfy the Goldstone theorem and to exhibit the hybridization of one-particle and collective excitations correctly. The results are applied to gases of 23 Na and 87 Rb atoms
Spin-isospin excitations induced by heavy ions at Saturne energies
International Nuclear Information System (INIS)
Hennino, T.
1989-01-01
Our program on the Spin-Isospin excitations started with the ( 3 He, 3 H) and ( 2 H, 2 He) reactions was extended with the heavy ion beams available at Saturne ( 12 C, 16 0, 20 Ne and 40 Ar) to study systematically the Δ excitation energy region. Projectile-ejectile dependences were measured. The Δ peak shift appears as a common feature in all charge exchange reactions. The first cross section calculations for the ( 12 C, 12 N) reaction are in good quantitative agreement with the data [fr
Ion range estimation by using dual energy computed tomography
Energy Technology Data Exchange (ETDEWEB)
Huenemohr, Nora; Greilich, Steffen [German Cancer Research Center (DKFZ), Heidelberg (Germany). Medical Physics in Radiation Oncology; Krauss, Bernhard [Siemens AG, Forchheim (Germany). Imaging and Therapy; Dinkel, Julien [German Cancer Research Center (DKFZ), Heidelberg (Germany). Radiology; Massachusetts General Hospital, Boston, MA (United States). Radiology; Gillmann, Clarissa [German Cancer Research Center (DKFZ), Heidelberg (Germany). Medical Physics in Radiation Oncology; University Hospital Heidelberg (Germany). Radiation Oncology; Ackermann, Benjamin [Heidelberg Ion-Beam Therapy Center (HIT), Heidelberg (Germany); Jaekel, Oliver [German Cancer Research Center (DKFZ), Heidelberg (Germany). Medical Physics in Radiation Oncology; Heidelberg Ion-Beam Therapy Center (HIT), Heidelberg (Germany); University Hospital Heidelberg (Germany). Radiation Oncology
2013-07-01
Inaccurate conversion of CT data to water-equivalent path length (WEPL) is one of the most important uncertainty sources in ion treatment planning. Dual energy CT (DECT) imaging might help to reduce CT number ambiguities with the additional information. In our study we scanned a series of materials (tissue substitutes, aluminum, PMMA, and other polymers) in the dual source scanner (Siemens Somatom Definition Flash). Based on the 80 kVp/140Sn kVp dual energy images, the electron densities Q{sub e} and effective atomic numbers Z{sub eff} were calculated. We introduced a new lookup table that translates the Q{sub e} to the WEPL. The WEPL residuals from the calibration were significantly reduced for the investigated tissue surrogates compared to the empirical Hounsfield-look-up table (single energy CT imaging) from (-1.0 {+-} 1.8)% to (0.1 {+-} 0.7)% and for non-tissue equivalent PMMA from -7.8% to -1.0%. To assess the benefit of the new DECT calibration, we conducted a treatment planning study for three different idealized cases based on tissue surrogates and PMMA. The DECT calibration yielded a significantly higher target coverage in tissue surrogates and phantom material (i.e. PMMA cylinder, mean target coverage improved from 62% to 98%). To verify the DECT calibration for real tissue, ion ranges through a frozen pig head were measured and compared to predictions calculated by the standard single energy CT calibration and the novel DECT calibration. By using this method, an improvement of ion range estimation from -2.1% water-equivalent thickness deviation (single energy CT) to 0.3% (DECT) was achieved. If one excludes raypaths located on the edge of the sample accompanied with high uncertainties, no significant difference could be observed. (orig.)
Li, Chenyang; Verma, Prakash; Hannon, Kevin P.; Evangelista, Francesco A.
2017-08-01
We propose an economical state-specific approach to evaluate electronic excitation energies based on the driven similarity renormalization group truncated to second order (DSRG-PT2). Starting from a closed-shell Hartree-Fock wave function, a model space is constructed that includes all single or single and double excitations within a given set of active orbitals. The resulting VCIS-DSRG-PT2 and VCISD-DSRG-PT2 methods are introduced and benchmarked on a set of 28 organic molecules [M. Schreiber et al., J. Chem. Phys. 128, 134110 (2008)]. Taking CC3 results as reference values, mean absolute deviations of 0.32 and 0.22 eV are observed for VCIS-DSRG-PT2 and VCISD-DSRG-PT2 excitation energies, respectively. Overall, VCIS-DSRG-PT2 yields results with accuracy comparable to those from time-dependent density functional theory using the B3LYP functional, while VCISD-DSRG-PT2 gives excitation energies comparable to those from equation-of-motion coupled cluster with singles and doubles.
Poolton, N R J; Quinn, F M; Pantos, E; Andersen, C E; Bøtter-Jensen, L; Johnsen, O; Murray, A S
2003-01-01
We demonstrate that the visible/UV luminescence from common feldspar crystals (NaAlSi sub 3 O sub 8 , KAlSi sub 3 O sub 8 and CaAl sub 2 Si sub 2 O sub 8) can be used to detect detailed L-edge and associated near-edge absorption structure of the main constituent atoms (Ca, K, Na, Al, Si), when exciting in the energy range 20-500 eV. Comparisons of the spectral features are drawn with similar measurements made on the associated materials SiO sub 2 , Al sub 2 O sub 3 and CaCO sub 3. The potential for using optically detected x-ray absorption spectroscopy as a method for identifying the luminescent components of mixed mineral samples is considered.
Lattice Boltzmann simulation for the energy and entropy of excitable systems
Institute of Scientific and Technical Information of China (English)
Deng Min-Yi; Tang Guo-Ning; Kong Ling-Jiang; Liu Mu-Ren
2011-01-01
The internal energy and the spatiotemporal entropy of excitable systems are investigated with the lattice Boltzmann method. The numerical results show that the breakup of spiral wave is attributed to the inadequate supply of energy, i.e., the internal energy of system is smaller than the energy of self-sustained spiral wave. It is observed that the average internal energy of a regular wave state reduces with its spatiotemporal entropy decreasing. Interestingly, although the energy difference between two regular wave states is very small, the different states can be distinguished obviously due to the large difference between their spatiotemporal entropies. In addition, when the unstable spiral wave converts into the spatiotemporal chaos, the internal energy of system decreases, while the spatiotemporal entropy increases, which behaves as the thermodynamic entropy in an isolated system.
International Nuclear Information System (INIS)
Wilhelmi, O.; Schartner, K.H.
2000-01-01
For pt.II see ibid., vol.11, p.45-58, 2000. Molecular oxygen O 2 was dissociated in collisions with protons and electrons in the intermediate velocity range (p + -energies: 17-800 keV, e - -energies: 0.2-2 keV). Fluorescence from excited atomic and singly ionised fragments and from singly ionised molecules was detected in the VUV and in the visible and near UV spectral range. Highly resolved spectra are presented for the VUV (46-131 nm) and the near UV/visible (340-605 nm) spectral range. Absolute emission cross-sections have been determined for dissociative ionisation and excitation leading to fluorescence in the VUV. Results are compared with published data. (orig.)
DEFF Research Database (Denmark)
List, Nanna Holmgaard; Olsen, Jógvan Magnus Haugaard; Rocha-Rinza, Tomás
2012-01-01
this task. We present an evaluation of the performance of commonly used XC-functionals for the prediction of excitation energies of GFP-like chromophores. In particular, we have considered the TD-DFT vertical excitation energies of chromophores displaying different charge states. We compare the quality...
Hinterberger, F; Altmeier, M; Bauer, F; Bisplinghoff, J; Büsser, K; Busch, M; Colberg, T; Diehl, O; Dohrmann, F; Engelhardt, H P; Eversheim, P D; Felden, O; Gebel, R; Glende, M; Greiff, J; Gross-Hardt, R; Hinterberger, F; Jahn, R; Jonas, E; Krause, H; Langkau, R; Lindemann, T; Lindlein, J; Maier, R; Maschuw, R; Mayer-Kuckuk, T; Meinerzhagen, A; Naehle, O; Prasuhn, D; Rohdjess, H; Rosendaal, D; Von Rossen, P; Schirm, N; Schulz-Rojahn, M; Schwarz, V; Scobel, W; Trelle, H J; Weise, E; Wellinghausen, A; Woller, K; Ziegler, R
2000-01-01
The EDDA experiment at the cooler synchrotron COSY measures proton-proton elastic scattering excitation functions in the momentum range 0.8 - 3.4 GeV/c. In phase 1 of the experiment, spin-averaged differential cross sections were measured continuously during acceleration with an internal polypropylene (CH sub 2) fiber target, taking particular care to monitor luminosity as a function of beam momentum. In phase 2, excitation functions of the analyzing power A sub N and the polarization correlation parameters A sub N sub N , A sub S sub S and A sub S sub L are measured using a polarized proton beam and a polarized atomic hydrogen beam target. The paper presents recent d sigma/d OMEGA and A sub N data. The results provide excitation functions and angular distributions of high precision and internal consistency. No evidence for narrow structures was found. The data are compared to recent phase shift solutions.
Chatterji, T; Jalarvo, N; Kumar, C M N; Xiao, Y; Brückel, Th
2013-07-17
We have investigated low energy nuclear spin excitations in the strongly correlated electron compound HoCrO3. We observe clear inelastic peaks at E = 22.18 ± 0.04 μeV in both energy loss and gain sides. The energy of the inelastic peaks remains constant in the temperature range 1.5-40 K at which they are observed. The intensity of the inelastic peak increases at first with increasing temperature and then decreases at higher temperatures. The temperature dependence of the energy and intensity of the inelastic peaks is very unusual compared to that observed in other Nd, Co, V and also simple Ho compounds. Huge quasielastic scattering appears at higher temperatures presumably due to the fluctuating electronic moments of the Ho ions that get increasingly disordered at higher temperatures. The strong quasielastic scattering may also originate in the first Ho crystal-field excitations at about 1.5 meV.
Energy Technology Data Exchange (ETDEWEB)
Zhukov, A.A. [N.L. Dukhov All-Russia Research Institute of Automatics, 127055 Moscow (Russian Federation); National Research Nuclear University (MEPhI), 115409 Moscow (Russian Federation); Shapiro, D.S., E-mail: shapiro.dima@gmail.com [N.L. Dukhov All-Russia Research Institute of Automatics, 127055 Moscow (Russian Federation); V.A. Kotel' nikov Institute of Radio Engineering and Electronics, Russian Academy of Sciences, 125009 Moscow (Russian Federation); Moscow Institute of Physics and Technology, Dolgoprudny, Moscow Region 141700 (Russian Federation); National University of Science and Technology MISIS, 119049 Moscow (Russian Federation); Remizov, S.V. [N.L. Dukhov All-Russia Research Institute of Automatics, 127055 Moscow (Russian Federation); V.A. Kotel' nikov Institute of Radio Engineering and Electronics, Russian Academy of Sciences, 125009 Moscow (Russian Federation); Pogosov, W.V. [N.L. Dukhov All-Russia Research Institute of Automatics, 127055 Moscow (Russian Federation); Moscow Institute of Physics and Technology, Dolgoprudny, Moscow Region 141700 (Russian Federation); Institute for Theoretical and Applied Electrodynamics, Russian Academy of Sciences, 125412 Moscow (Russian Federation); Lozovik, Yu.E. [N.L. Dukhov All-Russia Research Institute of Automatics, 127055 Moscow (Russian Federation); National Research Nuclear University (MEPhI), 115409 Moscow (Russian Federation); Moscow Institute of Physics and Technology, Dolgoprudny, Moscow Region 141700 (Russian Federation); Institute of Spectroscopy, Russian Academy of Sciences, 142190 Moscow Region, Troitsk (Russian Federation)
2017-02-12
We consider a superconducting qubit coupled to the nonstationary transmission line cavity with modulated frequency taking into account energy dissipation. Previously, it was demonstrated that in the case of a single nonadiabatical modulation of a cavity frequency there are two channels of a two-level system excitation which are due to the absorption of Casimir photons and due to the counterrotating wave processes responsible for the dynamical Lamb effect. We show that the parametric periodical modulation of the resonator frequency can increase dramatically the excitation probability. Remarkably, counterrotating wave processes under such a modulation start to play an important role even in the resonant regime. Our predictions can be used to control qubit-resonator quantum states as well as to study experimentally different channels of a parametric qubit excitation. - Highlights: • Coupled qubit-resonator system under the modulation of a resonator frequency is considered. • Counterrotating terms of the Hamiltonian are of importance even in the resonance. • Qubit excited state population is highest if driving frequency matches dressed-state energy.
International Nuclear Information System (INIS)
Yanguas-Gil, A.; Cotrino, J.; Gonzalez-Elipe, A.R.
2005-01-01
In this work the influence of the excited states on the electron-energy distribution function has been determined for an argon microwave discharge at low pressure. A collisional-radiative model of argon has been developed taking into account the most recent experimental and theoretical values of argon-electron-impact excitation cross sections. The model has been solved along with the electron Boltzmann equation in order to study the influence of the inelastic collisions from the argon excited states on the electron-energy distribution function. Results show that under certain conditions the excited states can play an important role in determining the shape of the distribution function and the mean kinetic energy of the electrons, deplecting the high-energy tail due to inelastic processes from the excited states, especially from the 4s excited configuration. It has been found that from the populations of the excited states an excitation temperature can be defined. This excitation temperature, which can be experimentally determined by optical emission spectroscopy, is lower than the electron kinetic temperature obtained from the electron-energy distribution function
Advanced Range Safety System for High Energy Vehicles
Claxton, Jeffrey S.; Linton, Donald F.
2002-01-01
The advanced range safety system project is a collaboration between the National Aeronautics and Space Administration and the United States Air Force to develop systems that would reduce costs and schedule for safety approval for new classes of unmanned high-energy vehicles. The mission-planning feature for this system would yield flight profiles that satisfy the mission requirements for the user while providing an increased quality of risk assessment, enhancing public safety. By improving the speed and accuracy of predicting risks to the public, mission planners would be able to expand flight envelopes significantly. Once in place, this system is expected to offer the flexibility of handling real-time risk management for the high-energy capabilities of hypersonic vehicles including autonomous return-from-orbit vehicles and extended flight profiles over land. Users of this system would include mission planners of Space Launch Initiative vehicles, space planes, and other high-energy vehicles. The real-time features of the system could make extended flight of a malfunctioning vehicle possible, in lieu of an immediate terminate decision. With this improved capability, the user would have more time for anomaly resolution and potential recovery of a malfunctioning vehicle.
Ren, Xinguo; Tkatchenko, Alexandre; Rinke, Patrick; Scheffler, Matthias
2011-04-15
The random-phase approximation (RPA) for the electron correlation energy, combined with the exact-exchange (EX) energy, represents the state-of-the-art exchange-correlation functional within density-functional theory. However, the standard RPA practice--evaluating both the EX and the RPA correlation energies using Kohn-Sham (KS) orbitals from local or semilocal exchange-correlation functionals--leads to a systematic underbinding of molecules and solids. Here we demonstrate that this behavior can be corrected by adding a "single excitation" contribution, so far not included in the standard RPA scheme. A similar improvement can also be achieved by replacing the non-self-consistent EX total energy by the corresponding self-consistent Hartree-Fock total energy, while retaining the RPA correlation energy evaluated using KS orbitals. Both schemes achieve chemical accuracy for a standard benchmark set of noncovalent intermolecular interactions.
Photodissociation of HCN and HNC isomers in the 7-10 eV energy range
Energy Technology Data Exchange (ETDEWEB)
Chenel, Aurelie; Roncero, Octavio, E-mail: octavio.roncero@csic.es [Instituto de Física Fundamental (IFF-CSIC), C.S.I.C., Serrano 123, 28006 Madrid (Spain); Aguado, Alfredo [Departamento de Química Física Aplicada (UAM), Unidad Asociada a IFF-CSIC, Facultad de Ciencias Módulo 14, Universidad Autónoma de Madrid, 28049 Madrid (Spain); Agúndez, Marcelino; Cernicharo, José [Instituto de Ciencia de Materiales de Madrid, CSIC, C/ Sor Juana Inés de la Cruz 3, 28049 Cantoblanco (Spain)
2016-04-14
The ultraviolet photoabsorption spectra of the HCN and HNC isomers have been simulated in the 7-10 eV photon energy range. For this purpose, the three-dimensional adiabatic potential energy surfaces of the 7 lowest electronic states, and the corresponding transition dipole moments, have been calculated, at multireference configuration interaction level. The spectra are calculated with a quantum wave packet method on these adiabatic potential energy surfaces. The spectra for the 3 lower excited states, the dissociative electronic states, correspond essentially to predissociation peaks, most of them through tunneling on the same adiabatic state. The 3 higher electronic states are bound, hereafter electronic bound states, and their spectra consist of delta lines, in the adiabatic approximation. The radiative lifetime towards the ground electronic states of these bound states has been calculated, being longer than 10 ns in all cases, much longer that the characteristic predissociation lifetimes. The spectra of HCN is compared with the available experimental and previous theoretical simulations, while in the case of HNC there are no previous studies to our knowledge. The spectrum for HNC is considerably more intense than that of HCN in the 7-10 eV photon energy range, which points to a higher photodissociation rate for HNC, compared to HCN, in astrophysical environments illuminated by ultraviolet radiation.
Munafò, A; Panesi, M; Magin, T E
2014-02-01
A Boltzmann rovibrational collisional coarse-grained model is proposed to reduce a detailed kinetic mechanism database developed at NASA Ames Research Center for internal energy transfer and dissociation in N(2)-N interactions. The coarse-grained model is constructed by lumping the rovibrational energy levels of the N(2) molecule into energy bins. The population of the levels within each bin is assumed to follow a Boltzmann distribution at the local translational temperature. Excitation and dissociation rate coefficients for the energy bins are obtained by averaging the elementary rate coefficients. The energy bins are treated as separate species, thus allowing for non-Boltzmann distributions of their populations. The proposed coarse-grained model is applied to the study of nonequilibrium flows behind normal shock waves and within converging-diverging nozzles. In both cases, the flow is assumed inviscid and steady. Computational results are compared with those obtained by direct solution of the master equation for the rovibrational collisional model and a more conventional multitemperature model. It is found that the proposed coarse-grained model is able to accurately resolve the nonequilibrium dynamics of internal energy excitation and dissociation-recombination processes with only 20 energy bins. Furthermore, the proposed coarse-grained model provides a superior description of the nonequilibrium phenomena occurring in shock heated and nozzle flows when compared with the conventional multitemperature models.
International Nuclear Information System (INIS)
Carlotti, G.; Madami, M.; Gubbiotti, G.; Tacchi, S.
2014-01-01
Sub-200 nm patterned magnetic dots are key elements for the design of magnetic switches, memory cells or elementary units of nanomagnetic logic circuits. In this paper, we analyse by micromagnetic simulations the magnetization reversal, the dissipated energy and the excited spin eigenmodes in bistable magnetic switches, consisting of elliptical nanodots with 100×60 nm lateral dimensions. Two different strategies for reversal are considered and the relative results compared: (i) the irreversible switching obtained by the application of an external field along the easy axis, in the direction opposite to the initial magnetization; (ii) the precessional switching accomplished by the application of a short magnetic field pulse, oriented perpendicular to the initial magnetization direction. The obtained results are discussed in terms of deviation from the macrospin behavior, energy dissipation and characteristics of the spectrum of spin eigenmodes excited during the magnetization reversal process
Evolution of collectivity in the 78Ni region: Coulomb excitation of 74Ni at intermediate energies.
Directory of Open Access Journals (Sweden)
Marchi T.
2014-03-01
Full Text Available The study of the collective properties of nuclear excitations far from stability provides information about the shell structure at extreme conditions. Spectroscopic observables such as the energy or the transition probabilities of the lowest states, in nuclei with large neutron excess, allow to probe the density and isospin dependence of the effective interaction. Indeed, it was recently shown that tensor and three-body forces play an important role in breaking and creating magic numbers. Emblematic is the case of the evolution of the Ni isotopic chain where several features showed up moving from the most neutron rich stable isotope (64Ni towards the 78Ni nucleus where the large neutron excess coincides with a double shell closure. In this framework, we have recently performed an experiment with the goal to extract the B(E2; 0+ → 2+ value for the 74Ni nucleus in an intermediate-energy Coulomb excitation experiment: preliminary results are discussed.
International Nuclear Information System (INIS)
Brice, D. K.
1979-01-01
1 - Description of problem or function: COREL calculates the final average projected range, standard deviation in projected range, standard deviation in locations transverse to projected range, and average range along path for energetic atomic projectiles incident on amorphous targets or crystalline targets oriented such that the projectiles are not incident along low index crystallographic axes or planes. RASE4 calculates the instantaneous average projected range, standard deviation in projected range, standard deviation in locations transverse to projected range, and average range along path for energetic atomic projectiles incident on amorphous targets or crystalline targets oriented such that the projectiles are not incident along low index crystallographic axes or planes. RASE4 also calculates the instantaneous rate at which the projectile is depositing energy into atomic processes (damage) and into electronic processes (electronic excitation), the average range of target atom recoils projected onto the direction of motion of the projectiles, and the standard deviation in the recoil projected range. DAMG2 calculates the distribution in depth of the energy deposited into atomic processes (damage), electronic processes (electronic excitation), or other energy-dependent quality produced by energetic atomic projectiles incident on amorphous targets or crystalline targets oriented such that the projectiles are not incident along low index crystallographic axes or planes. 2 - Method of solution: COREL: The truncated differential equation which governs the several variables being sought is solved through second-order by trapezoidal integration. The energy-dependent coefficients in the equation are obtained by rectangular integration over the Thomas-Fermi elastic scattering cross section. RASE4: The truncated differential equation which governs the range and straggling variables is solved through second-order by trapezoidal integration. The energy
Neutron-scattering study of low-energy excitations in triphenyl phosphite
Mayer, J; Massalska-Arodz, M; Janik, J A; Natkaniec, I; Steinsvoll, O
2002-01-01
The low-energy excitations in crystalline and glassy triphenyl phosphite were studied by inelastic incoherent neutron scattering with two different instruments. The results - the incoherent dynamic structure factor S(2 theta,omega) and the density of states G(omega) - were obtained using direct and inverted geometry time-of-flight spectrometers, respectively. The probable origin of the excess density of states in the glass (boson peak) is discussed. (orig.)
Neutron-scattering study of low-energy excitations in triphenyl phosphite
International Nuclear Information System (INIS)
Mayer, J.; Krawczyk, J.; Massalska-Arodz, M.; Janik, J.A.; Natkaniec, I.; Steinsvoll, O.
2002-01-01
The low-energy excitations in crystalline and glassy triphenyl phosphite were studied by inelastic incoherent neutron scattering with two different instruments. The results - the incoherent dynamic structure factor S(2θ,ω) and the density of states G(ω) - were obtained using direct and inverted geometry time-of-flight spectrometers, respectively. The probable origin of the excess density of states in the glass (boson peak) is discussed. (orig.)
Compact alpha-excited sources of low energy x-rays
International Nuclear Information System (INIS)
Amlauer, K.; Tuohy, I.
1976-01-01
A discussion is given of the use of alpha emitting isotopes, such as 210 Po and 244 Cm, for the production of low energy x-rays (less than 5.9 keV). The design of currently available sources is described, and x-ray fluxes observed from various target materials are presented. Commercial applications of the alpha excitation technique are briefly discussed
Papailiou, D. D. (Editor)
1975-01-01
Concepts are described that presently appear to have the potential for propulsion applications in the post-1990 era of space technology. The studies are still in progress, and only the current status of investigation is presented. The topics for possible propulsion application are lasers, nuclear fusion, matter-antimatter annihilation, electronically excited helium, energy exchange through the interaction of various fields, laser propagation, and thermonuclear fusion technology.
Low-energy Coulomb excitation of neutron-rich zinc isotopes
Van de Walle, J; Behrens, T; Bildstein, V; Blazhev, A; Cederkäll, J; Clément, E; Cocolios, T E; Davinson, T; Delahaye, P; Eberth, J; Ekström, A; Fedorov, D V; Fedosseev, V; Fraile, L M; Franchoo, S; Gernhäuser, R; Georgiev, G; Habs, D; Heyde, K; Huber, G; Huyse, M; Ibrahim, F; Ivanov, O; Iwanicki, J; Jolie, J; Kester, O; Köster, U; Kröll, T; Krücken, R; Lauer, M; Lisetskiy, A F; Lutter, R; Marsh, B A; Mayet, P; Niedermaier, O; Pantea, M; Raabe, R; Reiter, P; Sawicka, M; Scheit, H; Schrieder, G; Schwalm, D; Seliverstov, M D; Sieber, T; Sletten, G; Smirnova, N; Stanoiu, M; Stefanescu, I; Thomas, J C; Valiente-Dobón, J J; Van Duppen, P; Verney, D; Voulot, D; Warr, N; Weisshaar, D; Wenander, F; Wolf, B H; Zielinska, M
2009-01-01
At the radioactive ion beam facility REX-ISOLDE, neutron-rich zinc isotopes were investigated using low-energy Coulomb excitation. These experiments have resulted in B(E2,20) values in 74-80Zn, B(E2,42) values in 74,76Zn and the determination of the energy of the first excited 2 states in 78,80Zn. The zinc isotopes were produced by high-energy proton- (A=74,76,80) and neutron- (A=78) induced fission of 238U, combined with selective laser ionization and mass separation. The isobaric beam was postaccelerated by the REX linear accelerator and Coulomb excitation was induced on a thin secondary target, which was surrounded by the MINIBALL germanium detector array. In this work, it is shown how the selective laser ionization can be used to deal with the considerable isobaric beam contamination and how a reliable normalization of the experiment can be achieved. The results for zinc isotopes and the N=50 isotones are compared to collective model predictions and state-of-the-art large-scale shell-model calculations, i...
Accurate adiabatic energy surfaces for the ground and first excited states of He2+
International Nuclear Information System (INIS)
Lee, E.P.F.
1993-01-01
Different factors affecting the accuracy of the computed energy surfaces of the ground and first excited state of He 2 + have been examined, including the choice of the one-and many-particle bases, the configurational space in the MRCI (multi-reference configuration interaction) calculations and other corrections such as the Davidson and the full counterpoise (CP) correction. From basis-variation studies, it was concluded that multi-reference direct-CI calculations (MRDCI) using CASSCF MOs and/or natural orbitals (NOs) from a smaller CISD calculation, gave results close to full CI. The computed dissociation energies, D e , for the ground and first excited state of He 2 + were 2.4670 (2.4659) eV and 17.2 (17.1) cm -1 , respectively, at the highest level [without and with CP correction for basis-set superposition errors (BSSE)] of calculation with an [11s8p3d1f] GTO contraction, in reasonably good agreement with previous calculations, and estimated correct values, where available. It is believed that the computed D e , and the energy surface for the first excited state should be reasonably accurate. However, for the ground state, the effects of multiple f functions and/or functions of higher angular momentum have not been investigated owing to limitation of the available computing resources. This is probably the only weakness is the present study. (Author)
Distribution of radiative strength with excitation energy: the E1 and M1 giant resonances
International Nuclear Information System (INIS)
Brown, G.E.; Speth, J.
1979-01-01
Calculations of the giant dipole resonance in the particle-hole model, employing empirical values for the unperturbed particle and hole energies, have been unsuccessful in pushing the dipole state to a sufficiently high energy. it is argued that unperturbed levels correspondign to an effective mass of m*/m approx. 0.6 to 0.7 should be employed. The couplings of particles and holes to vibrations are the crucial ingredients in these considerations. More generally, it is argued that the effective mass relevant to excitations near the Fermi surface is that corresponding to empirical single-particle levels, m*/m greater than or equal to 1.0. For particle-hole excitations above the Fermi surface, it is a decreasing function of excitation energy, reaching the above values 0.6 to 0.7 for E greater than or equal to 2 dirac constant/b omega, dirac constant/sub omega/ being the shell spacing. This has the consequence of spreading out the M1 strength. A new interpretation of experimental strengths is proposed
Quantum conductance of carbon nanotubes in a wide energy range
International Nuclear Information System (INIS)
Zhang, Yong
2015-01-01
The differential conductance of armchair and zigzag carbon nanotubes (CNTs) in a wide energy range has been numerically calculated by using the tight-binding model and the Green’s function method. The effects of the contact coupling between CNTs and electrodes on conductance have been explored. The ballistic conductance is proportional to the band numbers and has a ladder-like feature. As the increase of the contact coupling, the conductance oscillations appear and they are robust against the coupling. More importantly, on the first step of the conductance ladder, the armchair CNTs have two quasi-periodic conductance oscillations, i.e. a rapid conductance oscillation superimposed on a slow fluctuation background; while the zigzag CNTs have only one conductance oscillation. But on the second conductance step, all CNTs have two quasi-periodic conductance oscillations. The physical origin of the conductance oscillations has been revealed
Passively-switched energy harvester for increased operational range
International Nuclear Information System (INIS)
Liu, Tian; Livermore, Carol; Pierre, Ryan St
2014-01-01
This paper presents modeling and experimental validation of a new type of vibrational energy harvester that passively switches between two dynamical modes of operation to expand the range of driving frequencies and accelerations over which the harvester effectively extracts power. In both modes, a driving beam with a low resonant frequency couples into ambient vibrations and transfers their energy to a generating beam that has a higher resonant frequency. The generating beam converts the mechanical power into electrical power. In coupled-motion mode, the driving beam bounces off the generating beam. In plucked mode, the driving beam deflects the generating beam until the driving beam passes from above the generating beam to below it or vice versa. Analytical system models are implemented numerically in the time domain for driving frequencies of 3 Hz to 27 Hz and accelerations from 0.1 g to 2.6 g, and both system dynamics and output power are predicted. A corresponding switched-dynamics harvester is tested experimentally, and its voltage, power, and dynamics are recorded. In both models and experiments, coupled-motion harvesting is observed at lower accelerations, whereas plucked harvesting and/or mixed mode harvesting are observed at higher accelerations. As expected, plucked harvesting outputs greater power than coupled-motion harvesting in both simulations and experiments. The predicted (1.8 mW) and measured (1.56 mW) maximum average power levels are similar under measured conditions at 0.5 g. When the system switches to dynamics that are characteristic of higher frequencies, the difference between predicted and measured power levels is more pronounced due to non-ideal mechanical interaction between the beams’ tips. Despite the beams’ non-ideal interactions, switched-dynamics operation increases the harvester’s operating range. (paper)
International Nuclear Information System (INIS)
Charusiri, W.; Eua-arporn, B.; Ubonwat, J.
2008-01-01
In 2004, the total energy consumption in Thailand increased 8.8 per cent, from 47,806 to 60,260 ktoe. Long-range Energy Alternatives Planning (LEAP) is an accounting tool that simulates future energy scenarios. According to a Business As Usual (BAU) case, the overall energy demand in Thailand is estimated to increase from 61,262 to 254,200 ktoe between 2004 and 2030. Commercial energy consumption, which comprises petroleum products, natural gas, coal and its products, and electricity, increased by 9.0 per cent in Thailand in 2004, and new and renewable energy increased by 7.8 per cent. Nearly 60 per cent of the total commercial energy supply in Thailand was imported and increased for a fifth year in a row. The changes in energy consumption can be attributed to population growth and increase in economic activity and development. 10 refs., 5 tabs., 14 figs
Environment-assisted Quantum Critical Effect for Excitation Energy Transfer in a LH2-type Trimer
Xu, Lan; Xu, Bo
2015-10-01
In this article, we are investigating excitation energy transfer (EET) in a basic unit cell of light-harvesting complex II (LH2), named a LH2-type trimer. Calculation of energy transfer efficiency (ETE) in the framework of non-Markovian environment is also implemented. With these achievements, we theoretically predict the environment-assisted quantum critical effect, where ETE exhibits a sudden change at the critical point of quantum phase transition (QPT) for the LH2-type trimer. It is found that highly efficient EET with nearly unit efficiency may occur in the vicinity of the critical point of QPT.
Energy Technology Data Exchange (ETDEWEB)
Zhang, Yijing, E-mail: yzhng123@illinois.edu; Moore, Keegan J.; Vakakis, Alexander F. [Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States); McFarland, D. Michael [Department of Aerospace Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States)
2015-12-21
We study passive pulse redirection and nonlinear targeted energy transfer in a granular network composed of two semi-infinite, ordered homogeneous granular chains mounted on linear elastic foundations and coupled by weak linear stiffnesses. Periodic excitation in the form of repetitive half-sine pulses is applied to one of the chains, designated as the “excited chain,” whereas the other chain is initially at rest and is regarded as the “absorbing chain.” We show that passive pulse redirection and targeted energy transfer from the excited to the absorbing chain can be achieved by macro-scale realization of the spatial analog of the Landau-Zener quantum tunneling effect. This is realized by finite stratification of the elastic foundation of the excited chain and depends on the system parameters (e.g., the percentage of stratification) and on the parameters of the periodic excitation. Utilizing empirical mode decomposition and numerical Hilbert transforms, we detect the existence of two distinct nonlinear phenomena in the periodically forced network; namely, (i) energy localization in the absorbing chain due to sustained 1:1 resonance capture leading to irreversible pulse redirection from the excited chain, and (ii) continuous energy exchanges in the form of nonlinear beats between the two chains in the absence of resonance capture. Our results extend previous findings of transient passive energy redirection in impulsively excited granular networks and demonstrate that steady state passive pulse redirection in these networks can be robustly achieved under periodic excitation.
The energy structure and decay channels of the 4p6-shell excited states in Sr
Kupliauskienė, A.; Kerevičius, G.; Borovik, V.; Shafranyosh, I.; Borovik, A.
2017-11-01
The ejected-electron spectra arising from the decay of the 4p{}5{{nln}}{\\prime }{l}{\\prime }{n}{\\prime\\prime }{l}{\\prime\\prime } autoionizing states in Sr atoms have been studied precisely at the incident-electron energies close to excitation and ionization thresholds of the 4{{{p}}}6 subshell. The excitation behaviors for 58 lines observed between 12 and 21 eV ejected-electron kinetic energy have been investigated. Also, the ab initio calculations of excitation energies, autoionization probabilities and electron-impact excitation cross sections of the states 4p{}5{{nln}}{\\prime }{l}{\\prime }{n}{\\prime\\prime }{l}{\\prime\\prime } (nl = 4d, 5s, 5p; {n}{\\prime }{l}{\\prime } = 4d, 5s, 5p; {n}{\\prime\\prime }{l}{\\prime\\prime } = 5s, 6s, 7s, 8s, 9s, 5p, 6p, 5d, 6d, 7d, 8d, 4f, 5g) have been performed by employing the large-scale configuration-interaction method in the basis of the solutions of Dirac-Fock-Slater equations. The obtained experimental and theoretical data have been used for the accurate identification of the 60 lines in ejected-electron spectra and the 68 lines observed earlier in photoabsorption spectra. The excitation and decay processes for 105 classified states in the 4p55s{}2{nl}, 4p54d{}2{nl} and 4p55s{{nln}}{\\prime }{l}{\\prime } configurations have been considered in detail. In particular, most of the states lying below the ionization threshold of the 4p6 subshell at 26.92 eV possess up to four decay channels with formation of Sr+ in 5s{}1/2, 4d{}3/{2,5/2} and 5p{}1/{2,3/2} states. Two-step autoionization and two-electron Auger transitions with formation of Sr2+ in the 4p6 {}1{{{S}}}0 ground state are the main decay paths for high-lying autoionizing states. The excitation threshold of the 4{{{p}}}6 subshell in Sr has been established at 20.98 ± 0.05 eV.
Low energy range dielectronic recombination of Fluorine-like Fe17+ at the CSRm
Khan, Nadir; Huang, Zhong-Kui; Wen, Wei-Qiang; Mahmood, Sultan; Dou, Li-Jun; Wang, Shu-Xing; Xu, Xin; Wang, Han-Bing; Chen, Chong-Yang; Chuai, Xiao-Ya; Zhu, Xiao-Long; Zhao, Dong-Mei; Mao, Li-Jun; Li, Jie; Yin, Da-Yu; Yang, Jian-Cheng; Yuan, You-Jin; Zhu, Lin-Fan; Ma, Xin-Wen
2018-05-01
The accuracy of dielectronic recombination (DR) data for astrophysics related ions plays a key role in astrophysical plasma modeling. The absolute DR rate coefficient of Fe17+ ions was measured at the main cooler storage ring at the Institute of Modern Physics, Lanzhou, China. The experimental electron-ion collision energy range covers the first Rydberg series up to n = 24 for the DR resonances associated with the {}2P1/2\\to {}2P3/2{{Δ }}n=0 core excitations. A theoretical calculation was performed by using FAC code and compared with the measured DR rate coefficient. Overall reasonable agreement was found between the experimental results and calculations. Moreover, the plasma rate coefficient was deduced from the experimental DR rate coefficient and compared with the available results from the literature. At the low energy range, significant discrepancies were found, and the measured resonances challenge state-of-the-art theory at low collision energies. Supported by the National Key R&D Program of China (2017YFA0402300), the National Natural Science Foundation of China through (11320101003, U1732133, 11611530684) and Key Research Program of Frontier Sciences, CAS (QYZDY-SSW-SLH006)
The 4p6 autoionization cross section of Rb atoms excited by low-energy electron impact
International Nuclear Information System (INIS)
Borovik, A; Roman, V; Kupliauskienė, A
2012-01-01
The autoionization cross section of rubidium atoms was obtained by measuring the total normalized intensities of ejected-electron spectra arising from the decay of the 4p 5 n 1 l 1 n 2 l 2 autoionizing levels. The electron impact energy range from the 4p 6 excitation threshold at 15.31 up to 50 eV was investigated. The cross section reaches the maximum value of (2.9 ± 0.6) × 10 −16 cm 2 at 21.8 eV impact energy. The general behaviours of the cross section and the role of particular autoionizing configurations in its formation were considered on the basis of large-scale configuration interaction calculations of energies, cross sections, autoionization probabilities in 5snl(n ⩽ 7; l ⩽ 4) and 4d nl(n ⩽ 5; l ⩽ 2) configurations as well as the measured excitation functions for the lowest levels in 5s 2 and 4d5s configurations. The resonance behaviour of the cross section between 15.3 and 18.5 eV impact energy is caused exclusively by the negative-ion resonances present close to the excitation thresholds of the (5s 2 ) 2 P and (4d5s) 4 P autoionizing levels. At higher impact energies, the autoionization cross section is composed of contributions from the high-lying quartet and doublet levels in 4d5s, 5p and 5s5p, 5d, 6s, 6p configurations. From the comparison of the present data with available experimental and calculated ionization cross sections, the 5s + 4p 6 direct ionization cross section of rubidium atoms was determined with the maximum value of (7.2 ± 2.2) × 10 −16 cm 2 at 36 eV. It was also found that the 4p 6 excitation–autoionization is the dominant indirect ionization process contributing over 30% of the total single ionization of rubidium atoms by electron impact in the 15.3–50 eV energy range. (paper)
Charge and energy dynamics in photo-excited poly(para-phenylenevinylene) systems
International Nuclear Information System (INIS)
Gisslen, L.; Johansson, A.; Stafstroem, S.
2004-01-01
We report results from simulations of charge and energy dynamics in poly(para-phenylenevinylene) (PPV) and PPV interacting with C 60 . The simulations were performed by solving the time-dependent Schroedinger equation and the lattice equation of motion simultaneously and nonadiabatically. The electronic system and the coupling of the electrons to the lattice were described by an extended three-dimensional version of the Su-Schrieffer-Heeger model, which also included an external electric field. Electron and lattice dynamics following electronic excitations at different energies have been simulated. The effect of additional lattice energy was also included in the simulations. Our results show that both exciton diffusion and transitions from high to lower lying excitations are stimulated by increasing the lattice energy. Also field induced charge separation occurs faster if the lattice energy is increased. This separation process is highly nonadiabatic and involves a significant rearrangement of the electron distribution. In the case of PPV coupled to C 60 , we observe a spontaneous charge separation. The separation time is in this case limited by the local concentration of C 60 molecules close to the PPV chain
Fission excitation function for 19F + 194,196,198Pt at near and above barrier energies
Directory of Open Access Journals (Sweden)
Singh Varinderjit
2015-01-01
Full Text Available Fission excitation functions for 19F + 194,196,198Pt reactions populating 213,215,217Fr compound nuclei are reported. Out of these three compound nuclei, 213Fr is a shell closed (N=126 compound nucleus and the other two are away from the shell closure. From a comparison of the experimental fission cross-sections with the statistical model predictions, it is observed that the fission cross-sections are underestimated by the statistical model predictions using shell corrected finite range rotating liquid drop model (FRLDM fission barriers. Further the FRLDM fission barriers are reduced to fit the fission cross-sections over the entire measured energy range.
The mechanism of three-body process of energy transfer from excited xenon atoms to molecules
International Nuclear Information System (INIS)
Wojciechowski, K.; Forys, M.
1999-01-01
The mechanism of energy transfer from Xe(6 s[3/2] 1 ) resonance state (E=8.44 eV) and higher excited Xe(6p, 6p', 6 d) atoms produced in pulse radiolysis to molecules have been discussed. The analysis of the kinetic data for these processes shows that in the sensitized photolysis and radiolysis of Xe-M mixtures the excited atoms decay in 'ordinary' two-body reaction: Xe(6s[3/2] 1 0 )+M→products (r.1) and in fast 'accelerated' third order process: Xe(6s[3/2] 1 0 )+M+Xe→products (r.2) The discussion shows that three-body process occurs via reactions: Xe(6s[3/2] 1 0 )+Xe k w ↔ k d Xe 2 ** (r.2a) Xe 2 **+M k q →[Xe 2 M]*→products (r.2b) It was shown that this mechanism concerns also higher excited Xe atoms and can explain a similar process in He-M mixtures and suggests that it is a general mechanism of energy transfer in all irradiated rare gas-molecule systems
Energy Technology Data Exchange (ETDEWEB)
Amusia, M.Ya. [The Racah Institute of Physics, Hebrew University, 91904 Jerusalem (Israel); A F Ioffe Physical-Technical Institute, 194921 St Petersburg (Russian Federation); Mikhailov, A.I.; Mikhailov, I.A. [St Petersburg Nuclear Physics Institute, Gatchina, 188350 St Petersburg (Russian Federation)
1999-10-28
Double ionization and ionization with excitation of helium-like ions with Z>>1 from 2 {sup 1}S and 2 {sup 3}S states on the absorption of a high-frequency photon have been considered. The analytical calculation is performed in the non-relativistic photon energy range in the lowest order of perturbation theory in the inter-electron interaction. Coulomb wavefunctions and the Coulomb Green function are used as a zeroth-order approximation. Differential and total cross sections of the processes are expressed via the corresponding values for the single photoionization. The photoelectron energy spectrum is obtained in the marginal energy range (i.e. for p{sub 1}>>p{sub 2}, p{sub 1} and p{sub 2} momenta of photoelectrons) for the double-ionization process. Simple relations between the cross sections of double ionization and ionization with excitation are derived. (author)
DEFF Research Database (Denmark)
Kadkhodazadeh, Shima; Wagner, Jakob Birkedal; Joseph, Virginia
2013-01-01
in an optical experiment and electron energy loss intensity at energies corresponding to excitation wavelengths used for optical probing. This inverse relation exists independent on specific nanoaggregate geometries and is mainly controlled by the gap size between the particles forming the aggregate. The ratio...... between two- and one-photon excited SERS measured at different excitation wavelengths provides information about local fields in the hottest spots and their dependence on the photon energy. Our data verify experimentally the predicted increase of local optical fields in the hot spots with increasing wave...
Resonant states in 13C and 16,17O at high excitation energy
International Nuclear Information System (INIS)
Rodrigues, M R D; Borello-Lewin, T; Miyake, H; Duarte, J L M; Rodrigues, C L; Horodynski-Matsushigue, L B; Ukita, G M; Cappuzzello, F; Foti, A; Cavallaro, M; Agodi, C; Cunsolo, A; Carbone, D; Bondi, M; Napoli, M De; Roeder, B T; Linares, R; Lombardo, I
2014-01-01
The 9 Be( 6 Li,d) 13 C and 12,13 C( 6 Li,d) 16,17 O reactions were measured at the São Paulo Pelletron-Enge-Spectrograph facility at 25.5 MeV incident energy. The nuclear emulsion detection technique was applied. Several narrow resonances were populated up to approximately 17 MeV of excitation energy. An excellent energy resolution was obtained: 40 keV for 13 C and 15-30 keV for 16 O. The upper limit for the resonance widths were determined. Recently, d-a angular correlations were measured at θ d = 0° with incident energy of 25 MeV using the LNS Tandem-MAGNEX Spectrometer facility
Resonant states in 13C and 16,17O at high excitation energy
Rodrigues, M. R. D.; Borello-Lewin, T.; Miyake, H.; Duarte, J. L. M.; Rodrigues, C. L.; Horodynski-Matsushigue, L. B.; Ukita, G. M.; Cappuzzello, F.; Cavallaro, M.; Foti, A.; Agodi, C.; Cunsolo, A.; Carbone, D.; Bondi, M.; De Napoli, M.; Roeder, B. T.; Linares, R.; Lombardo, I.
2014-12-01
The 9Be(6Li,d)13C and 12,13C(6Li,d)16,17O reactions were measured at the São Paulo Pelletron-Enge-Spectrograph facility at 25.5 MeV incident energy. The nuclear emulsion detection technique was applied. Several narrow resonances were populated up to approximately 17 MeV of excitation energy. An excellent energy resolution was obtained: 40 keV for 13C and 15-30 keV for 16O. The upper limit for the resonance widths were determined. Recently, d-a angular correlations were measured at θd = 0° with incident energy of 25 MeV using the LNS Tandem-MAGNEX Spectrometer facility.
Xie, Yu; Jiang, Shengshi; Zheng, Jie; Lan, Zhenggang
2017-12-21
Photoinduced excited-state electron and energy transfer processes are crucial in biological photoharvesting systems and organic photovoltaic devices. We discuss the construction of a diabatic vibronic Hamiltonian for the proper treatment of these processes involving the projection approach acting on both electronic wave functions and vibrational modes. In the electronic part, the wave function projection approach is used to construct the diabatic Hamiltonian in which both local excited states and charge-transfer states are included on the same footing. For the vibrational degrees of freedom, the vibronic couplings in the diabatic Hamiltonian are obtained in the basis of the pseudonormal modes localized on each monomer site by applying delocalized-to-localized mode projection. This systematic approach allows us to construct the vibronic diabatic Hamiltonian in molecular aggregates.
Probing core polarization around 78Ni: intermediate energy Coulomb excitation of 74Ni
Directory of Open Access Journals (Sweden)
Marchi T.
2013-12-01
We have recently measured the B(E2; 0+ → 2+ of the 74Ni nucleus in an intermediate-energy Coulomb excitation experiment performed at the National Superconducting Cyclotron Laboratory of the Michigan State University. The 74Ni secondary beam has been produced by fragmentation of 86Kr at 140 AMeV on a thick Be target. Selected radioactive fragments impinged on a secondary 197Au target where the measurement of the emitted γ-rays allows to extract the Coulomb excitation cross section and related structure information. Preliminary B(E2 values do not point towards an enhancement of the transition matrix element and the comparison to what was already measured by Aoi and co-workers in [1] opens new scenarios in the interpretation of the shell evolution of the Z=28 isotopes.
Electron energy distributions and excitation rates in high-frequency argon discharges
International Nuclear Information System (INIS)
Ferreira, C.M.; Loureiro, J.
1983-06-01
The electron energy distribution functions and rate coefficients for excitation and ionisation in argon under the action of an uniform high-frequency electric field were calculated by numerically solving the homogeneous Boltzmann equation. Analytic calculations in the limiting cases ω>>νsub(c) and ω<<νsub(c), where ω is the wave angular frequency and νsub(c) is the electron-neutral collision frequency for momentum transfer, are also presented and shown to be in very good agreement with the numerical computations. The results reported here are relevant for the modelling of high-frequency discharges in argon and, in particular, for improving recent theoretical descriptions of a plasma column sustained by surface microwaves. The properties of surface wave produced plasmas make them interesting as possible substitutes for other more conventional plasma sources for such important applications as plasma chemistry laser excitation, plasma etching spectroscopic sources etc...
Schmid, S.A.; Abbel, R.J.; Schenning, A.P.H.J.; Meijer, E.W.; Herz, L.M.
2010-01-01
We have investigated the extent to which delocalization of the ground-state and excited-state wave functions of a p-conjugated molecule affects the excitation energy transfer (EET) between such molecules. Using femtosecond photoluminescence spectroscopy, we experimentally monitored the EET along
Luminescence of the SrCl2:Pr crystals under high-energy excitation
International Nuclear Information System (INIS)
Antonyak, O.T.; Voloshinovskii, A.S.; Vistovskyy, V.V.; Stryganyuk, G.B.; Kregel, O.P.
2014-01-01
The present research was carried out in order to elucidate the mechanisms of energy transfer from the crystal lattice to Pr 3+ ions in SrCl 2 . The luminescence excitation and emission spectra as well as luminescence kinetics of the SrCl 2 :Pr single crystals containing 0.2 mol% Pr were investigated at 300 and 10 K using the vacuum ultraviolet (VUV) synchrotron radiation. The X-ray excited luminescence spectra of the SrCl 2 :Pr (C Pr =0.2 and 0.5 mol%) and SrCl 2 :Pr, K (C Pr =1.5 mol%; C K =1.5 mol%) crystals were studied at 294 and 80 K. Under optical excitation of the samples in the Pr 3+ absorption bands, there were observed five fast ultraviolet emissions assigned to the 4f 1 5d→4f 2 transitions, and two long-wave bands corresponding to the f–f transitions. Furthermore, the intrinsic emission bands of SrCl 2 were observed at 10 K. The X-ray excited luminescence spectrum of the SrCl 2 :Pr crystal containing 0.2 mol% Pr, besides intrinsic emission band near 400 nm, has got a long-wave band at about 490 nm of the Pr 3+ centers. There were not observed any emission bands of the Pr 3+ centers corresponding to the 4f 1 5d–4f 2 transitions in the X-ray excited luminescence spectrum of the SrCl 2 :Pr crystal. The possible mechanisms of energy transfer from the SrCl 2 matrix to the Pr 3+ centers are discussed. -- Highlights: • Spectral-luminescent properties of SrCl 2 :Pr have been investigated. • The identification of emission 4f–4f and 5d–4f bands of Pr 3+ ions was performed. • Adding of potassium prevents clustering of the Pr 3+ centers in the SrCl 2 :Pr, K crystals. • Under X-ray excitation at 80–300 K only Pr 3+ 4f–4f and intrinsic emission is observed
Control of base-excited dynamical systems through piezoelectric energy harvesting absorber
Abdelmoula, H.; Dai, H. L.; Abdelkefi, A.; Wang, L.
2017-09-01
The spring-mass absorber usually offers a good control to dynamical systems under direct base excitations for a specific value of the excitation frequency. As the vibrational energy of a primary dynamical system is transferred to the absorber, it gets dissipated. In this study, this energy is no longer dissipated but converted to available electrical power by designing efficient energy harvesters. A novel design of a piezoelectric beam installed inside an elastically-mounted dynamical system undergoing base excitations is considered. A design is carried out in order to determine the properties and dimensions of the energy harvester with the constraint of simultaneously decreasing the oscillating amplitudes of the primary dynamical system and increasing the harvested power of the energy harvesting absorber. An analytical model for the coupled system is constructed using Euler-Lagrange principle and Galerkin discretization. Different strategies for controlling the primary structure displacement and enhancing the harvested power as functions of the electrical load resistance and thickness of the beam substrate are performed. The linear polynomial approximation of the system’s key parameters as a function of the beam’s substrate thickness is first carried out. Then, the gradient method is applied to determine the adequate values of the electrical load resistance and thickness of the substrate under the constraints of minimizing the amplitudes of the primary structure or maximizing the levels of the harvested power. After that, an iterative strategy is considered in order to simultaneously minimize the amplitudes of the primary structure and maximize the levels of the harvested power as functions of the thickness of the substrate and electrical load resistance. In addition to harmonic excitations, the coupled system subjected to a white noise is explored. Through this analysis, the load resistance and thickness of the substrate of the piezoelectric energy harvester
International Nuclear Information System (INIS)
Kleymann, G.
1976-01-01
This paper is a compilation of results of experimental and theoretical studies on the term diagrams of odd-even nuclei from the isotope series of Nb, Tc, Rh and Ag, published until October 1975. As a relatively simple interpretation of the excitements of these nuclei, De Shalit proposed the coupling of a particle, whose quantum numbers may be derived from a shell model, to excited states of the core of the nucleus. (orig./BJ) [de
Akhtar, Parveen; Lingvay, Mónika; Kiss, Teréz; Deák, Róbert; Bóta, Attila; Ughy, Bettina; Garab, Győző; Lambrev, Petar H
2016-04-01
Light-harvesting complex II (LHCII), the major peripheral antenna of Photosystem II in plants, participates in several concerted mechanisms for regulation of the excitation energy and electron fluxes in thylakoid membranes. In part, these include interaction of LHCII with Photosystem I (PSI) enhancing the latter's absorption cross-section - for example in the well-known state 1 - state 2 transitions or as a long-term acclimation to high light. In this work we examined the capability of LHCII to deliver excitations to PSI in reconstituted membranes in vitro. Proteoliposomes with native plant thylakoid membrane lipids and different stoichiometric ratios of LHCII:PSI were reconstituted and studied by steady-state and time-resolved fluorescence spectroscopy. Fluorescence emission from LHCII was strongly decreased in PSI-LHCII membranes due to trapping of excitations by PSI. Kinetic modelling of the time-resolved fluorescence data revealed the existence of separate pools of LHCII distinguished by the time scale of energy transfer. A strongly coupled pool, equivalent to one LHCII trimer per PSI, transferred excitations to PSI with near-unity efficiency on a time scale of less than 10ps but extra LHCIIs also contributed significantly to the effective antenna size of PSI, which could be increased by up to 47% in membranes containing 3 LHCII trimers per PSI. The results demonstrate a remarkable competence of LHCII to increase the absorption cross-section of PSI, given the opportunity that the two types of complexes interact in the membrane. Copyright © 2016 Elsevier B.V. All rights reserved.
van Meer, R; Gritsenko, O V; Baerends, E J
2014-10-14
In recent years, several benchmark studies on the performance of large sets of functionals in time-dependent density functional theory (TDDFT) calculations of excitation energies have been performed. The tested functionals do not approximate exact Kohn-Sham orbitals and orbital energies closely. We highlight the advantages of (close to) exact Kohn-Sham orbitals and orbital energies for a simple description, very often as just a single orbital-to-orbital transition, of molecular excitations. Benchmark calculations are performed for the statistical average of orbital potentials (SAOP) functional for the potential [J. Chem. Phys. 2000, 112, 1344; 2001, 114, 652], which approximates the true Kohn-Sham potential much better than LDA, GGA, mGGA, and hybrid potentials do. An accurate Kohn-Sham potential does not only perform satisfactorily for calculated vertical excitation energies of both valence and Rydberg transitions but also exhibits appealing properties of the KS orbitals including occupied orbital energies close to ionization energies, virtual-occupied orbital energy gaps very close to excitation energies, realistic shapes of virtual orbitals, leading to straightforward interpretation of most excitations as single orbital transitions. We stress that such advantages are completely lost in time-dependent Hartree-Fock and partly in hybrid approaches. Many excitations and excitation energies calculated with local density, generalized gradient, and hybrid functionals are spurious. There is, with an accurate KS, or even the LDA or GGA potentials, nothing problematic about the "band gap" in molecules: the HOMO-LUMO gap is close to the first excitation energy (the optical gap).
Razjivin, A P; Lukashev, E P; Kompanets, V O; Kozlovsky, V S; Ashikhmin, A A; Chekalin, S V; Moskalenko, A A; Paschenko, V Z
2017-09-01
Pathways of intramolecular conversion and intermolecular electronic excitation energy transfer (EET) in the photosynthetic apparatus of purple bacteria remain subject to debate. Here we experimentally tested the possibility of EET from the bacteriochlorophyll (BChl) Soret band to the singlet S 2 level of carotenoids using femtosecond pump-probe measurements and steady-state fluorescence excitation and absorption measurements in the near-ultraviolet and visible spectral ranges. The efficiency of EET from the Soret band of BChl to S 2 of the carotenoids in light-harvesting complex LH2 from the purple bacterium Ectothiorhodospira haloalkaliphila appeared not to exceed a few percent.
Directory of Open Access Journals (Sweden)
K. Nishio
2015-09-01
Full Text Available Mass distributions of fission fragments from the compound nuclei 180Hg and 190Hg formed in fusion reactions 36Ar + 144Sm and 36Ar + 154Sm, respectively, were measured at initial excitation energies of E⁎(Hg180=33–66 MeV and E⁎(Hg190=48–71 MeV. In the fission of 180Hg, the mass spectra were well reproduced by assuming only an asymmetric-mass division, with most probable light and heavy fragment masses A¯L/A¯H=79/101. The mass asymmetry for 180Hg agrees well with that obtained in the low-energy β+/EC-delayed fission of 180Tl, from our earlier ISOLDE(CERN experiment. Fission of 190Hg is found to proceed in a similar way, delivering the mass asymmetry of A¯L/A¯H=83/107, throughout the measured excitation energy range. The persistence as a function of excitation energy of the mass-asymmetric fission for both proton-rich Hg isotopes gives strong evidence for the survival of microscopic effects up to effective excitation energies of compound nuclei as high as 40 MeV. This behavior is different from fission of actinide nuclei and heavier mercury isotope 198Hg.
Excitation of contained modes by high energy nuclei and correlated cyclotron emission
International Nuclear Information System (INIS)
Coppi, B.; Penn, G.; Riconda, C.
1997-01-01
In experiments with fusing plasmas, enhanced radiation emission at the harmonics of the cyclotron frequency of fusion reaction products has been observed. A theory is presented that explains key features of these observations and indicates the possibility of extracting significant information about the fusion product population distribution, both in velocity space and over the plasma cross section. The considered model is consistent in particular with the fact that, in DT plasmas, the radiation peaks occur at frequencies corresponding to harmonics of the α particles cyclotron frequency Ω a evaluated at the outer edge of the plasma column, and that a transition to a open-quotes continuumclose quotes spectrum at high frequencies (ω approx-gt 7Ω α ) can be identified. In this model, the radiation is the result of the excitation of radially open-quotes containedclose quotes modes which are driven unstable by the fusion products. The modes considered to be responsible for the discrete part of the spectrum are spatially localized near the plasma edge. The radial containment, which is associated mainly with the inhomogeneity of the plasma density, is in fact a fundamental characteristic since only contained modes can grow out of a relatively weak mode-particle interaction and justify the detected emission power levels. The contained mode is a solution to a set of macroscopic equations, in which the electron motion is tied to that of the magnetic field (Hall effect). The growth rate has been evaluated considering the particle orbits in a toroidal confinement configuration and modelling the distribution function of the interacting particles with the energy at birth before slowing down occurs. The growth rate depends linearly on the α-particle density and can be larger than, or of the order of, the bounce frequency of the magnetically trapped α-particles, which can have a resonant interaction with the mode. According to the theoretical model presented, the discrete
Mechanism and models for collisional energy transfer in highly excited large polyatomic molecules
International Nuclear Information System (INIS)
Gilbert, R. G.
1995-01-01
Collisional energy transfer in highly excited molecules (say, 200-500 kJ mol -1 above the zero-point energy of reactant, or of product, for a recombination reaction) is reviewed. An understanding of this energy transfer is important in predicting and interpreting the pressure dependence of gas-phase rate coefficients for unimolecular and recombination reactions. For many years it was thought that this pressure dependence could be calculated from a single energy-transfer quantity, such as the average energy transferred per collision. However, the discovery of 'super collisions' (a small but significant fraction of collisions which transfer abnormally large amounts of energy) means that this simplistic approach needs some revision. The 'ordinary' (non-super) component of the distribution function for collisional energy transfer can be quantified either by empirical models (e.g., an exponential-down functional form) or by models with a physical basis, such as biased random walk (applicable to monatomic or diatomic collision partners) or ergodic (for polyatomic collision partners) treatments. The latter two models enable approximate expressions for the average energy transfer to be estimated from readily available molecular parameters. Rotational energy transfer, important for finding the pressure dependence for recombination reactions, can for these purposes usually be taken as transferring sufficient energy so that the explicit functional form is not required to predict the pressure dependence. The mechanism of 'ordinary' energy transfer seems to be dominated by low-frequency modes of the substrate, whereby there is sufficient time during a vibrational period for significant energy flow between the collision partners. Super collisions may involve sudden energy flow as an outer atom of the substrate is squashed between the substrate and the bath gas, and then is moved away from the interaction by large-amplitude motion such as a ring vibration or a rotation; improved
Energy Technology Data Exchange (ETDEWEB)
Chiari, L.; Jones, D. B.; Thorn, P. A.; Pettifer, Z. [School of Chemical and Physical Sciences, Flinders University, GPO Box 2100, Adelaide, SA 5001 (Australia); Duque, H. V. [School of Chemical and Physical Sciences, Flinders University, GPO Box 2100, Adelaide, SA 5001 (Australia); Departamento de Física, Universidade Federal de Juiz de Fora, Juiz de Fora, MG (Brazil); Silva, G. B. da [School of Chemical and Physical Sciences, Flinders University, GPO Box 2100, Adelaide, SA 5001 (Australia); Universidade Federal de Mato Grosso, Barra do Garças, Mato Grosso (Brazil); Limão-Vieira, P. [Laboratório de Colisões Atómicas e Moleculares, CEFITEC, Departamento de Física, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica (Portugal); Duflot, D. [Laboratoire de Physique des Lasers, Atomes et Molécules, UMR CNRS 8523, Université Lille, F-59655 Villeneuve d’Ascq Cedex (France); Hubin-Franskin, M.-J.; Delwiche, J. [Départment de Chimie, Université de Liège, Institut de Chimie-Bât. B6C, B-4000 Liège 1 (Belgium); Blanco, F. [Departamento de Física Atómica, Molecular y Nuclear, Universidad Complutense de Madrid, Madrid E-28040 (Spain); García, G. [Instituto de Física Fundamental, CSIC, Madrid E-28006 (Spain); and others
2014-07-14
We report on measurements of differential cross sections (DCSs) for electron impact excitation of a series of Rydberg electronic-states in α-tetrahydrofurfuryl alcohol (THFA). The energy range of these experiments was 20–50 eV, while the scattered electron was detected in the 10°–90° angular range. There are currently no other experimental data or theoretical computations against which we can directly compare the present measured results. Nonetheless, we are able to compare our THFA DCSs with earlier cross section measurements for Rydberg-state electronic excitation for tetrahydrofuran, a similar cyclic ether, from Do et al. [J. Chem. Phys. 134, 144302 (2011)]. In addition, “rotationally averaged” elastic DCSs, calculated using our independent atom model with screened additivity rule correction approach are also reported. Those latter results give integral cross sections consistent with the optical theorem, and supercede those from the only previous study of Milosavljević et al. [Eur. Phys. J. D 40, 107 (2006)].
Ghosh, Soumen
This dissertation investigates the photophysical and structural dynamics that allow carotenoids to serve as efficient excitation energy transfer donor to chlorophyll acceptors in photosynthetic light harvesting proteins. Femtosecond transient grating spectroscopy with optical heterodyne detection has been employed to follow the nonradiative decay pathways of carotenoids and excitation energy transfer to chlorophylls. It was found that the optically prepared S2 (11Bu+) state of beta-carotene decays in 12 fs fs to populate an intermediate electronic state, Sx, which then decays nonradiatively to the S 1 state. The ultrafast rise of the dispersion component of the heterodyne transient grating signal reports the formation of Sx intermediate since the rise of the dispersion signal is controlled by the loss of stimulated emission from the S2 state. These findings were extended to studies of peridinin, a carbonyl substituted carotenoid that serves as a photosynthetic light-harvesting chromophore in dinoflagellates. Numerical simulations using nonlinear response formalism and the multimode Brownian oscillator model assigned the Sx intermediate to a torsionally distorted structure evolving on the S2 potential surface. The decay of the Sx state is promoted by large amplitude out-of-plane torsional motions and is significantly retarded by solvent friction owing to the development of an intramolecular charge transfer character in peridinin. The slowing of the nonradiative decay allows the Sx state to transfer significant portion of the excitation energy to chlorophyll a acceptors in the peridinin-chlorophyll a protein. The results of heterodyne transient grating study on peridinin-chlorophyll a protein suggests two distinct energy transfer channels from peridinin to chlorophyll a: a 30 fs process involving quantum coherence and delocalized peridinin-Chl states and an incoherent, 2.5 ps process involving the distorted S2 state of peridinin. The torsional evolution on the S2
A new analysis technique to measure fusion excitation functions with large beam energy dispersions
Figuera, P.; Di Pietro, A.; Fisichella, M.; Lattuada, M.; Shotter, A. C.; Ruiz, C.; Zadro, M.
2018-01-01
Peculiar nuclear structures of two colliding nuclei such has clustering, neutron halo/skin or very low breakup thresholds can affect the reaction dynamics below the Coulomb barrier and this may also have astrophysical consequences. In order to have a better understanding of this topic, in the last decade, several experiments were performed. A typical experimental challenge of such studies is the need to measure excitation functions below the Coulomb barrier, having a strong energy dependence, with rather large beam energy dispersions inside the target. This may easily lead to ambiguities in associating the measured cross section with a proper beam energy. In this paper a discussion on this topic is reported and a new technique to deal with the above problem will be proposed.
Microscopic unitary description of tidal excitations in high-energy string-brane collisions
D'Appollonio, Giuseppe; Russo, Rodolfo; Veneziano, Gabriele
2013-01-01
The eikonal operator was originally introduced to describe the effect of tidal excitations on higher-genus elastic string amplitudes at high energy. In this paper we provide a precise interpretation for this operator through the explicit tree-level calculation of generic inelastic transitions between closed strings as they scatter off a stack of parallel Dp-branes. We perform this analysis both in the light-cone gauge, using the Green-Schwarz vertex, and in the covariant formalism, using the Reggeon vertex operator. We also present a detailed discussion of the high energy behaviour of the covariant string amplitudes, showing how to take into account the energy factors that enhance the contribution of the longitudinally polarized massive states in a simple way.
Effects of Energy Dissipation on the Parametric Excitation of a Coupled Qubit-Cavity System
Remizov, S. V.; Zhukov, A. A.; Shapiro, D. S.; Pogosov, W. V.; Lozovik, Yu. E.
2018-02-01
We consider a parametrically driven system of a qubit coupled to a cavity taking into account different channels of energy dissipation. We focus on the periodic modulation of a single parameter of this hybrid system, which is the coupling constant between the two subsystems. Such a modulation is possible within the superconducting realization of qubit-cavity coupled systems, characterized by an outstanding degree of tunability and flexibility. Our major result is that energy dissipation in the cavity can enhance population of the excited state of the qubit in the steady state, while energy dissipation in the qubit subsystem can enhance the number of photons generated from vacuum. We find optimal parameters for the realization of such dissipation-induced amplification of quantum effects. Our results might be of importance for the full control of quantum states of coupled systems as well as for the storage and engineering of quantum states.
High Excitation Transfer Efficiency from Energy Relay Dyes in Dye-Sensitized Solar Cells
Hardin, Brian E.
2010-08-11
The energy relay dye, 4-(Dicyanomethylene)-2-methyl-6-(4- dimethylaminostyryl)-4H-pyran (DCM), was used with a near-infrared sensitizing dye, TT1, to increase the overall power conversion efficiency of a dye-sensitized solar cell (DSC) from 3.5% to 4.5%. The unattached DCM dyes exhibit an average excitation transfer efficiency (EÌ?TE) of 96% inside TT1-covered, mesostructured TiO2 films. Further performance increases were limited by the solubility of DCM in an acetonitrile based electrolyte. This demonstration shows that energy relay dyes can be efficiently implemented in optimized dye-sensitized solar cells, but also highlights the need to design highly soluble energy relay dyes with high molar extinction coefficients. © 2010 American Chemical Society.
Application of radionuclide sources for excitation in energy-dispersive X-ray fluorescence analysis
International Nuclear Information System (INIS)
Hoffmann, P.
1986-01-01
X-ray fluorescence (XRF) analysis is in broad application in many fields of science where elemental determinations are necessary. Solid and liquid samples are analyzed by this method. Solids are introduced in thin or thick samples as melted glass, pellets, powders or as original specimen. The excitation of X-ray spectra can be performed by specific and polychromic radiation of X-ray tubes, by protons, deuterons, α-particles, heavy ions and synchrotron radiation from accelerators and by α-particles, X- and γ-rays and by bremsstrahlung generated by β - -particles from radionuclide sources. The radionuclides are devided into groups with respect to their decay mode and the energy of the emitted radiation. The broad application of radionuclides in XRF excitation is shown in examples as semi-quantitative analysis of glasses, as quantitative analysis of coarse ceramics and as quantitative determination of heavy elements (mainly actinides) in solutions. The advantages and disadvantages of radionuclide excitation in XRF analysis are discussed. (orig.) [de
International Nuclear Information System (INIS)
Liu Ningyu; Pasko, Victor P
2010-01-01
It has been established that production of NO-γ emission in pulsed corona discharges is dominated by the energy transfer from N 2 (A 3 Σ u + ) to the NO ground state NO(X 2 Π r ) while direct excitation by electron impact is negligible. However, recent studies suggest that the electron impact excitation plays a more important role. In this work, we report modelling results of NO-γ emission associated with streamer discharges using two cross section data sets available in the literature. The first set was originally reported by Mojarrabi et al (1996 Phys. Rev. A 54 2977-82) and later updated by Brunger et al (2000 J. Phys. B: At. Mol. Opt. Phys. 33 809-19); the second set was published by Hayashi (1990 Nonequilibrium Processes in Partially Ionized Gases (NATO Advanced Science Institutes Series, Series B, Physics vol 220) ed M Capitelli and J N Bardsley (New York: Plenum) pp 333-40). According to the results, the role played by the electron impact excitation in the production of NO-γ is drastically different when different cross sections are used. The results indicate that the first data set leads to better agreement with experimental measurements. (fast track communication)
Picosecond excitation energy transfer of allophycocyanin studied in solution and in crystals.
Ranjbar Choubeh, Reza; Sonani, Ravi R; Madamwar, Datta; Struik, Paul C; Bader, Arjen N; Robert, Bruno; van Amerongen, Herbert
2018-03-01
Cyanobacteria perform photosynthesis with the use of large light-harvesting antennae called phycobilisomes (PBSs). These hemispherical PBSs contain hundreds of open-chain tetrapyrrole chromophores bound to different peptides, providing an arrangement in which excitation energy is funnelled towards the PBS core from where it can be transferred to photosystem I and/or photosystem II. In the PBS core, many allophycocyanin (APC) trimers are present, red-light-absorbing phycobiliproteins that covalently bind phycocyanobilin (PCB) chromophores. APC trimers were amongst the first light-harvesting complexes to be crystallized. APC trimers have two spectrally different PCBs per monomer, a high- and a low-energy pigment. The crystal structure of the APC trimer reveals the close distance (~21 Å) between those two chromophores (the distance within one monomer is ~51 Å) and this explains the ultrafast (~1 ps) excitation energy transfer (EET) between them. Both chromophores adopt a somewhat different structure, which is held responsible for their spectral difference. Here we used spectrally resolved picosecond fluorescence to study EET in these APC trimers both in crystallized and in solubilized form. We found that not all closely spaced pigment couples consist of a low- and a high-energy pigment. In ~10% of the cases, a couple consists of two high-energy pigments. EET to a low-energy pigment, which can spectrally be resolved, occurs on a time scale of tens of picoseconds. This transfer turns out to be three times faster in the crystal than in the solution. The spectral characteristics and the time scale of this transfer component are similar to what have been observed in the whole cells of Synechocystis sp. PCC 6803, for which it was ascribed to EET from C-phycocyanin to APC. The present results thus demonstrate that part of this transfer should probably also be ascribed to EET within APC trimers.
International Nuclear Information System (INIS)
Tei, Go; Nakatani, Masatoshi; Ishihara, Hajime
2013-01-01
Peripheral light harvesting complex (LH2), which is found in photosynthetic antenna systems of purple photosynthetic bacteria, has important functions in the photosynthetic process, such as harvesting sunlight and transferring its energy to the photosynthetic reaction center. The key component in excitation energy transfer (EET) between LH2s is B850, which is a characteristic ring-shaped aggregate of pigments usually formed by 18 or 16 bacteriochlorophylls in LH2. We theoretically study the strategy of the ring-shaped aggregate structure, which maximizes EET efficiency, by using the standard Frenkel exciton model and the self-consistent calculation method for the Markovian quantum master equation and Maxwell equation. As a result, we have revealed a simple but ingenious strategy of the ring-shaped aggregate structure. The combination of three key properties of the ring unit system maximizes the EET efficiency, namely the large dipole moment of aggregates causes the basic improvement of EET efficiency, and the isotropic nature and the large occupying area are critically effective to remove the disorder-induced shielding that inhibits EET in the presence of the randomness of orientation and alignment of carriers of excitation energy. (paper)
Influence of primary fragment excitation energy and spin distributions on fission observables
Litaize, Olivier; Thulliez, Loïc; Serot, Olivier; Chebboubi, Abdelaziz; Tamagno, Pierre
2018-03-01
Fission observables in the case of 252Cf(sf) are investigated by exploring several models involved in the excitation energy sharing and spin-parity assignment between primary fission fragments. In a first step the parameters used in the FIFRELIN Monte Carlo code "reference route" are presented: two parameters for the mass dependent temperature ratio law and two constant spin cut-off parameters for light and heavy fragment groups respectively. These parameters determine the initial fragment entry zone in excitation energy and spin-parity (E*, Jπ). They are chosen to reproduce the light and heavy average prompt neutron multiplicities. When these target observables are achieved all other fission observables can be predicted. We show here the influence of input parameters on the saw-tooth curve and we discuss the influence of a mass and energy-dependent spin cut-off model on gamma-rays related fission observables. The part of the model involving level densities, neutron transmission coefficients or photon strength functions remains unchanged.
Vibrational and electronic excitation of hexatriacontane thin films by low energy electron impact
International Nuclear Information System (INIS)
Vilar, M.R.; Schott, M.; Pfluger, P.
1990-01-01
Thin polycrystalline films of hexatriacontane (HTC) were irradiated with low energy (E=0.5--15 eV) electrons, and off-specular backscattered electron spectra were measured. Below E∼7 eV, single and multiple vibrational excitations only are observed, which relax the electrons down to the bottom of the HTC conduction band. Due to the negative electron affinity of HTC, thermal electrons are emitted into vacuum. Structure in the backscattered electron current at kinetic energies about 1.5 and 4 eV are associated to conduction band density of states. Above E∼7 eV, the dominant losses correspond to electronic excitations, excitons, or above a threshold (energy of the electron inside the HTC film) at 9.2±0.1 eV, electron--hole pair generation. The latter process is very efficient and reaches a yield of the order of one ∼11 eV. Evidence for chemical reaction above E∼4 eV is observed
Tei, Go; Nakatani, Masatoshi; Ishihara, Hajime
2013-06-01
Peripheral light harvesting complex (LH2), which is found in photosynthetic antenna systems of purple photosynthetic bacteria, has important functions in the photosynthetic process, such as harvesting sunlight and transferring its energy to the photosynthetic reaction center. The key component in excitation energy transfer (EET) between LH2s is B850, which is a characteristic ring-shaped aggregate of pigments usually formed by 18 or 16 bacteriochlorophylls in LH2. We theoretically study the strategy of the ring-shaped aggregate structure, which maximizes EET efficiency, by using the standard Frenkel exciton model and the self-consistent calculation method for the Markovian quantum master equation and Maxwell equation. As a result, we have revealed a simple but ingenious strategy of the ring-shaped aggregate structure. The combination of three key properties of the ring unit system maximizes the EET efficiency, namely the large dipole moment of aggregates causes the basic improvement of EET efficiency, and the isotropic nature and the large occupying area are critically effective to remove the disorder-induced shielding that inhibits EET in the presence of the randomness of orientation and alignment of carriers of excitation energy.
Low-energy heavy-atom impact as a tool for production and classification of doubly excited states
International Nuclear Information System (INIS)
Andersen, N.
1985-01-01
Low-energy heavy-atom impact may be an efficient way of preferentially populating doubly excited levels. Using neon as an example, this paper discusses why this is so. The similarity of the structure of the energy level diagrams for doubly excited neon and the level scheme for neutral magnesium is pointed out, suggesting that collective quantum numbers may describe the electron pair. (orig.)
International Nuclear Information System (INIS)
Morozov, A.; Kruecken, R.; Ulrich, A.; Wieser, J.
2006-01-01
Side-view intensity profiles of fluorescent light were measured for neon and nitrogen excited with 12 keV electron beams at gas pressures from 250 to 1400 hPa. The intensity profiles were compared with theoretical profiles calculated using the CASINO program which performs Monte Carlo simulations of electron scattering. It was assumed that the spatial distribution of fluorescent intensity is directly proportional to the spatial distribution of energy loss by primary electrons. The comparison shows good correlation of experimental data and the results of numeric simulations
Doping dependence of low-energy quasiparticle excitations in superconducting Bi2212.
Ino, Akihiro; Anzai, Hiroaki; Arita, Masashi; Namatame, Hirofumi; Taniguchi, Masaki; Ishikado, Motoyuki; Fujita, Kazuhiro; Ishida, Shigeyuki; Uchida, Shinichi
2013-12-05
: The doping-dependent evolution of the d-wave superconducting state is studied from the perspective of the angle-resolved photoemission spectra of a high-Tc cuprate, Bi2Sr2CaCu2 O8+δ (Bi2212). The anisotropic evolution of the energy gap for Bogoliubov quasiparticles is parametrized by critical temperature and superfluid density. The renormalization of nodal quasiparticles is evaluated in terms of mass enhancement spectra. These quantities shed light on the strong coupling nature of electron pairing and the impact of forward elastic or inelastic scatterings. We suggest that the quasiparticle excitations in the superconducting cuprates are profoundly affected by doping-dependent screening.
An accurate energy-range relationship for high-energy electron beams in arbitrary materials
International Nuclear Information System (INIS)
Sorcini, B.B.; Brahme, A.
1994-01-01
A general analytical energy-range relationship has been derived to relate the practical range, R p to the most probable energy, E p , of incident electron beams in the range 1 to 50 MeV and above, for absorbers of any atomic number. In the present study only Monte Carlo data determined with the new ITS.3 code have been employed. The standard deviations of the mean deviation from the Monte Carlo data at any energy are about 0.10, 0.12, 0.04, 0.11, 0.04, 0.03, 0.02 mm for Be, C, H 2 O, Al, Cu, Ag and U, respectively, and the relative standard deviation of the mean is about 0.5% for all materials. The fitting program gives some priority to water-equivalent materials, which explains the low standard deviation for water. A small error in the fall-off slope can give a different value for R p . We describe a new method which reduces the uncertainty in the R p determination, by fitting an odd function to the descending portion of the depth-dose curve in order to accurately determine the tangent at the inflection point, and thereby the practical range. An approximate inverse relation is given expressing the most probable energy of an electron beam as a function of the practical range. The resultant relative standard error of the energy is less than 0.7%, and the maximum energy error ΔE p is less than 0.3 MeV. (author)
DEFF Research Database (Denmark)
Hedegård, Erik D.; Jensen, Hans Jørgen Aagaard; Knecht, Stefan
2013-01-01
-MC-srDFT) excitation energies calculated over a larger benchmark set of molecules with predominantly single reference character yield good agreement with their reference values, and are in general comparable to the CAM-B3LYP functional. The SOPPA-srDFT scheme is tested for a subset of molecules used for benchmarking...
International Nuclear Information System (INIS)
Dhara, Sangita; Misra, N.L.; Aggarwal, S.K.; Venugopal, V.
2010-01-01
An energy dispersive X-ray fluorescence method for determination of cadmium (Cd) in uranium (U) matrix using continuum source of excitation was developed. Calibration and sample solutions of cadmium, with and without uranium were prepared by mixing different volumes of standard solutions of cadmium and uranyl nitrate, both prepared in suprapure nitric acid. The concentration of Cd in calibration solutions and samples was in the range of 6 to 90 μg/mL whereas the concentration of Cd with respect to U ranged from 90 to 700 μg/g of U. From the calibration solutions and samples containing uranium, the major matrix uranium was selectively extracted using 30% tri-n-butyl phosphate in dodecane. Fixed volumes (1.5 mL) of aqueous phases thus obtained were taken directly in specially designed in-house fabricated leak proof Perspex sample cells for the energy dispersive X-ray fluorescence measurements and calibration plots were made by plotting Cd Kα intensity against respective Cd concentration. For the calibration solutions not having uranium, the energy dispersive X-ray fluorescence spectra were measured without any extraction and Cd calibration plots were made accordingly. The results obtained showed a precision of 2% (1σ) and the results deviated from the expected values by < 4% on average.
International Nuclear Information System (INIS)
Djerad, M.T.
1987-01-01
This study concerns mainly ionising collisions involving excited states in a saturated mixture of K-Rb vapours, at thermal energy. The experimental method consists into continuous resonant two steps laser excitation of the atoms (n ≤ 10) and mass spectrometry of ion currents. Radiative and collisional relaxation of the atoms create a complex medium. The most efficient collisional processes are Penning ionisation and Hornbeck-Molnar ionisation. In the heteronuclear system Rb(n1) + K(4P), the following exit channels may be operative: Rb(n1) + K(4P) → Rb + + e - + K Rb(n1) + K(4p) → K + + e - + Rb Rb(n1) + K(4P) → KRb + + e - . The measurements show that the first channel has an average cross section ∼ 10 -13 cm 2 . Those of the other channels are at least three orders of magnitude smaller and thus comparatively negligible. The data obtained from 5D to 10S allow to conclude that the flux in the entrance channel ionises at large separation between Rb(n1) and K(4P). The process of ionisation is dominated by polarisation forces, exchange forces being negligible. In the present mixture, Hornbeck-Molnar ionisation leads to homonuclear molecular ions K 2 + , Rb 2 + as well as the heteronuclear one KRb + . We have measured the rate coefficients for the systems: K(n1) + Rb → KRb + + e - Rb(n1) + K → KRb + + e - . The rate coefficients increase with the excitation energy of the level n1; they do not exhibit fundamental differences with those measured in pure alkali vapours [fr
International Nuclear Information System (INIS)
Cabrera-Trujillo, R.; Sabin, J.R.; Oddershede, J.
2003-01-01
Recently, Porter observed [L.E. Porter, Int. J. Quantum Chem. 90, 684 (2002)] that the mean excitation energy and stopping cross section of a target, obtained from fitting experimental data at given projectile charge to a modified Bethe-Block theory, gives projectile dependent results. The main result of his work is that there is a trend for the inferred target mean excitation energy, to decrease as the projectile atomic number increases. However, this result is inconsistent with the usual definition of the mean excitation energy as a function of target excitation properties only. Here we present an explanation of Porter's results based on the Bethe theory extended to take projectile electronic structure explicitly into account
Sutherland, B. R.
2016-02-01
It is well established that two-dimensional internal plane waves and modes in uniformly stratified fluid efficiently transfer energy to smaller scale waves and ultimately turbulent mixing through parametric subharmonic instability (PSI). The numerical simulations of MacKinnon & Winters (GRL 2005) predicted PSI should act efficiently to disrupt the internal tide. However, while in situ observations showed the presence of PSI, it was not found to be appreciable. One reason for the discrepancy between simulations and observations is that the former examined an internal mode in uniformly stratified fluid whereas, in reality, the internal tide exists in non-uniform stratification and is manifest as sinusoidal oscillations of the thermocline. Through theory supported by numerical simulations, it is shown that internal modes in non-uniform stratification immediately excite superharmonics, not subharmonic disturbances. These have double the horizontal wavenumber and double the frequency of the parent mode and hence move with the same horizontal phase speed of the parent mode. As the disturbances grow in amplitude, however, they interact with the parent mode generating small-scale vertically propagating internal waves within the strongly stratified layer. The occurrence of PSI over very long times can occur, as in the simulations of Hazewinkel and Winters (JPO 2011). However, a comprehensive understanding of the energy cascade from the internal tide to small scales must consider the evolution of excited superharmonic disturbances.
Excitation energy and angular momentum dependence of the nuclear level densities
International Nuclear Information System (INIS)
Razavi, R.; Kakavand, T.; Behkami, A. N.
2007-01-01
We have investigated the excitation energy (E) dependence of nuclear level density for Bethe formula and constant temperature model. The level density parameter aa nd the back shifted energy from the Bethe formula are obtained by fitting the complete level schemes. Also the level density parameters from the constant temperature model have been determined for several nuclei. we have shown that the microscopic theory provides more precise information on the nuclear level densities. On the other hand, the spin cut-off parameter and effective moment of inertia are determined by studying of the angular momentum (J) dependence of the nuclear level density, and effective moment of inertia is compared with rigid body value.
DEFF Research Database (Denmark)
Gavnholt, Jeppe; Olsen, Thomas; Engelund, Mads
2008-01-01
is a density-functional method closely resembling standard density-functional theory (DFT), the only difference being that in Delta SCF one or more electrons are placed in higher lying Kohn-Sham orbitals instead of placing all electrons in the lowest possible orbitals as one does when calculating the ground......-state energy within standard DFT. We extend the Delta SCF method by allowing excited electrons to occupy orbitals which are linear combinations of Kohn-Sham orbitals. With this extra freedom it is possible to place charge locally on adsorbed molecules in the calculations, such that resonance energies can...... be estimated, which is not possible in traditional Delta SCF because of very delocalized Kohn-Sham orbitals. The method is applied to N2, CO, and NO adsorbed on different metallic surfaces and compared to ordinary Delta SCF without our modification, spatially constrained DFT, and inverse...
Excitation function of elastic scattering on 12C + 4He system, at low energies
International Nuclear Information System (INIS)
Perez-Torres, R.; Aguilera, E. F.; Martinez-Quiroz, E.; Murillo, G.; Belyaeva, T. L.; Maldonado-Velazquez, M.
2011-01-01
Interactions in the 12 C + 4 He system are of great interest in astrophysics and to help determine the relative abundances of elements in stars, at the end of helium burning [1, 2]. The Instituto Nacional de Investigaciones Nucleares (ININ) in Mexico, have made measurements of elastic scattering for this system, using the inverse kinematics method with thick white gas [3, 4], for E CM (0.5 - 4 MeV) θ CM = 180 o . In this work we obtain excitation functions of elastic scattering of 12 C + 4 He system with angular and energy dependence; E CM = 0.5 - 4 MeV and θ CM 100 o -170 o .Using inverse kinematics method with thick white gas and energy loss tables. (Author)
Ferreira da Silva, F.; Lange, E.; Limão-Vieira, P.; Jones, N. C.; Hoffmann, S. V.; Hubin-Franskin, M.-J.; Delwiche, J.; Brunger, M. J.; Neves, R. F. C.; Lopes, M. C. A.; de Oliveira, E. M.; da Costa, R. F.; Varella, M. T. do N.; Bettega, M. H. F.; Blanco, F.; García, G.; Lima, M. A. P.; Jones, D. B.
2015-10-01
The electronic spectroscopy of isolated furfural (2-furaldehyde) in the gas phase has been investigated using high-resolution photoabsorption spectroscopy in the 3.5-10.8 eV energy-range, with absolute cross section measurements derived. Electron energy loss spectra are also measured over a range of kinematical conditions. Those energy loss spectra are used to derive differential cross sections and in turn generalised oscillator strengths. These experiments are supported by ab initio calculations in order to assign the excited states of the neutral molecule. The good agreement between the theoretical results and the measurements allows us to provide the first quantitative assignment of the electronic state spectroscopy of furfural over an extended energy range.
International Nuclear Information System (INIS)
Ferreira da Silva, F.; Lange, E.; Limão-Vieira, P.; Jones, N. C.; Hoffmann, S. V.; Hubin-Franskin, M.-J.; Delwiche, J.; Brunger, M. J.
2015-01-01
The electronic spectroscopy of isolated furfural (2-furaldehyde) in the gas phase has been investigated using high-resolution photoabsorption spectroscopy in the 3.5–10.8 eV energy-range, with absolute cross section measurements derived. Electron energy loss spectra are also measured over a range of kinematical conditions. Those energy loss spectra are used to derive differential cross sections and in turn generalised oscillator strengths. These experiments are supported by ab initio calculations in order to assign the excited states of the neutral molecule. The good agreement between the theoretical results and the measurements allows us to provide the first quantitative assignment of the electronic state spectroscopy of furfural over an extended energy range
Energy Technology Data Exchange (ETDEWEB)
Ferreira da Silva, F.; Lange, E. [Laboratório de Colisões Atómicas e Moleculares, CEFITEC, Departamento de Física, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica (Portugal); Limão-Vieira, P., E-mail: plimaovieira@fct.unl.pt, E-mail: michael.brunger@flinders.edu.au, E-mail: maplima@ifi.unicamp.br [Laboratório de Colisões Atómicas e Moleculares, CEFITEC, Departamento de Física, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica (Portugal); School of Chemical and Physical Sciences, Flinders University, GPO Box 2100, Adelaide, South Australia 5001 (Australia); Jones, N. C.; Hoffmann, S. V. [ISA, Department of Physics and Astronomy, Aarhus University, Ny Munkegade, DK-8000 Århus C (Denmark); Hubin-Franskin, M.-J.; Delwiche, J. [Départment de Chimie, Institut de Chimie-Bât. B6C, Université de Liège, B-4000 Liège 1 (Belgium); Brunger, M. J., E-mail: plimaovieira@fct.unl.pt, E-mail: michael.brunger@flinders.edu.au, E-mail: maplima@ifi.unicamp.br [School of Chemical and Physical Sciences, Flinders University, GPO Box 2100, Adelaide, South Australia 5001 (Australia); Institute of Mathematical Sciences, University of Malaya, 50603 Kuala Lumpur (Malaysia); and others
2015-10-14
The electronic spectroscopy of isolated furfural (2-furaldehyde) in the gas phase has been investigated using high-resolution photoabsorption spectroscopy in the 3.5–10.8 eV energy-range, with absolute cross section measurements derived. Electron energy loss spectra are also measured over a range of kinematical conditions. Those energy loss spectra are used to derive differential cross sections and in turn generalised oscillator strengths. These experiments are supported by ab initio calculations in order to assign the excited states of the neutral molecule. The good agreement between the theoretical results and the measurements allows us to provide the first quantitative assignment of the electronic state spectroscopy of furfural over an extended energy range.
Directory of Open Access Journals (Sweden)
Di Pietro Alessia
2017-01-01
Full Text Available In the present paper it is described an analysis procedure suited for experiments where cross-sections strongly varying with energy are measured using beams having large energy dispersion. These cross-sections are typically the sub-barrier fusion excitation function of reactions induced by radioactive beams. The large beam energy dispersion, typical of these experiments, can lead to ambiguities in the association of the effective beam energy to the reaction product yields and consequently to an error in the determination of the excitation function. As a test case, the approach is applied to the experiments 6Li+120Sn and 7Li+119Sn measured in the energy range 14 MeV ≤ Ec.m. ≤28 MeV. The complete fusion cross sections are deduced from activation measurements using the stacked target technique. The results of these experiments, that employ the two weakly-bound stable Li isotopes, show that the complete fusion cross sections above the barrier are suppressed of about 70% and 85% with respect to the Universal Fusion Function, used as a standard reference, in the 6Li and 7Li induced reactions respectively. Moreover, the excitation functions of the two systems at energies below the barrier, do not show significant differences, despite the two systems have different n-transfer Qvalue.
Calculation of 0-0 excitation energies of organic molecules by CIS(D) quantum chemical methods
International Nuclear Information System (INIS)
Grimme, Stefan; Izgorodina, Ekaterina I.
2004-01-01
The accuracy and reliability of the CIS(D) quantum chemical method and a spin-component scaled variant (SCS-CIS(D)) are tested for calculating 0-0 excitation energies of organic molecules. The ground and excited state geometries and the vibrational zero-point corrections are taken from (TD)DFT-B3LYP calculations. In total 32 valence excited states of different character are studied: π → π* states of polycyclic aromatic compounds/polyenes and n → π* states of carbonyl, thiocarbonyl and aza(azo)-aromatic compounds. This set is augmented by two systems of special interest, i.e., indole and the TICT state of dimethylaminbenzonitrile (DMABN). Both methods predict excitation energies that are on average higher than experiment by about 0.2 eV. The errors are found to be quite systematic (with a standard deviation of about 0.15 eV) and especially SCS-CIS(D) provides a more balanced treatment of π → π* vs. n → π* states. For the test suite of states, both methods clearly outperform the (TD)DFT-B3LYP approach. Opposed to previous conclusions about the performance of CIS(D), these methods can be recommended as reliable and efficient tools for computational studies of excited state problems in organic chemistry. In order to obtain conclusive results, however, the use of optimized excited state geometries and comparison with observables (0-0 excitation energies) are necessary
International Nuclear Information System (INIS)
Thirumalai, D.; Onda, K.; Truhlar, D.G.
1981-01-01
Coupled-channels calculations based on an effective potential are presented for electron scattering by CO 2 at 10 eV impact energy. The processes studied are pure elastic scattering, rotational excitation, and vibrational excitation of the asymmetric stretch; the vibrational excitation is always accompanied by rotational excitation. The quantities calculated are differential, partial, integral, and momentum transfer cross sections, both state to state and summed over final rotational states for a given final vibrational level. The effective potential is based on the INDOX2/1s method for the static and polarization potentials and the semiclassical exchange approximation for the exchange potential. There are no empirical parameters. The present calculations are compared to experiment and to previous calculations where available, and we also perform calculations with an altered polarization potential to further elucidate the reasons for the differences from one of the previous calculations. The agreement of the present results with the experimental rotationally summed, vibrationally inelastic differential cross section is excellent
Wide Temperature Range Hybrid Energy Storage Device, Phase I
National Aeronautics and Space Administration — This proposal concerns the fabrication of a hybrid battery capacitor (HBC) using Eltron's knowledge gained in battery and capacitor research. Energy storage systems...
International Nuclear Information System (INIS)
Dineen, D.; Ó Gallachóir, B.P.
2017-01-01
This paper estimates the potential energy savings in the Irish residential sector by 2020 due to the introduction of an ambitious retrofit programme. We estimate the technical energy savings potential of retrofit measures targeting energy efficiency of the space and water heating end uses of the 2011 stock of residential dwellings between 2012 and 2020. We build eight separate scenarios, varying the number of dwellings retrofitted and the depth of retrofit carried out in order to investigate the range of energy savings possible. In 2020 the estimated technical savings potential lies in the range from 1713 GWh to 10,817 GWh, but is more likely to fall within the lower end of this range, i.e. between 1700 and 4360 GWh. When rebound effects are taken into account this reduces further to 1100 GWh and 2800 GWh per annum. The purpose of this paper was to test the robustness of the NEEAP target savings for residential retrofit, i.e. 3000 GWh by 2020. We conclude that this target is technically feasible but very challenging and unlikely to be achieved based on progress to date. It will require a significant shift towards deeper retrofit measures compared to what has been achieved by previous schemes. - Highlights: • Paper estimates range of energy savings likely from Irish residential retrofit. • Achieving NEEAP target savings of 3000 GWh by 2020 is feasible but very challenging. • Likely savings of 1100–2800 GWh per annum in 2020, including rebound. • NEEAP target unlikely to be achieved based on current trends.
Zeng, Qiao; Liang, WanZhen
2015-10-07
The time-dependent density functional theory (TDDFT) has become the most popular method to calculate the electronic excitation energies, describe the excited-state properties, and perform the excited-state geometric optimization of medium and large-size molecules due to the implementation of analytic excited-state energy gradient and Hessian in many electronic structure software packages. To describe the molecules in condensed phase, one usually adopts the computationally efficient hybrid Quantum Mechanics/Molecular Mechanics (QM/MM) models. Here, we extend our previous work on the energy gradient of TDDFT/MM excited state to account for the mutual polarization effects between QM and MM regions, which is believed to hold a crucial position in the potential energy surface of molecular systems when the photoexcitation-induced charge rearrangement in the QM region is drastic. The implementation of a simple polarizable TDDFT/MM (TDDFT/MMpol) model in Q-Chem/CHARMM interface with both the linear response and the state-specific features has been realized. Several benchmark tests and preliminary applications are exhibited to confirm our implementation and assess the effects of different treatment of environmental polarization on the excited-state properties, and the efficiency of parallel implementation is demonstrated as well.
FEL based photon collider of TeV energy range
International Nuclear Information System (INIS)
Saldin, E.L.; Shnejdmiller, E.A.; Sarantsev, V.P.; Yurkov, M.V.
1994-01-01
Physical principles of operation of high energy photon linear colliders (PLC) based on the Compton backscattering of laser photons on high energy electrons are discussed. The main emphasis is put on the analysis of a possibility to construct the PLC with the center of mass energy 0.5-2 TeV. Free electron laser (FEL) is considered as a source of primary photons. Proposed FEL system consists of a tunable FEL oscillator (output power ∼ 1 - 10 MW) with subsequent amplification of the master signal in a FEL amplifier up to the power ∼ 3 x 10 11 W. The FEL parameters are optimized, restrictions on the electron beam and FEL magnetic system parameters are formulated and problems of technical realization are discussed. It is shown that the FEL technique provides the most suitable way to construct photon linear collider on the base of future generation linear collider. 22 refs., 10 figs., 2 tabs
Autonomous Vehicles Have a Wide Range of Possible Energy Impacts
Energy Technology Data Exchange (ETDEWEB)
Austin Brown, Brittany Repac, Jeff Gonder
2013-07-15
Self-driving or “autonomous” vehicles (AVs) have leapt from science fiction into the forefront of transportation technology news. The technology is likely still years away from widespread commercial adoption, but the recent progress makes it worth considering the potential national impacts of widespread implementation. This poster makes an initial assessment of the energy impacts of AV adoptionon a per-vehicle basis and on total personal vehicle fuel use. While AVs offer numerous potential advantages in energy use, there are significant factors that could decrease or even eliminate the energy benefits under some circumstances. This analysis attempts to describe, quantify, and combine many of the possible effects. The nature and magnitude of these effects remain highly uncertain. This set of effects is very unlikely to be exhaustive, but this analysis approach can serve as a base for future estimates.
A pair natural orbital implementation of the coupled cluster model CC2 for excitation energies.
Helmich, Benjamin; Hättig, Christof
2013-08-28
We demonstrate how to extend the pair natural orbital (PNO) methodology for excited states, presented in a previous work for the perturbative doubles correction to configuration interaction singles (CIS(D)), to iterative coupled cluster methods such as the approximate singles and doubles model CC2. The original O(N(5)) scaling of the PNO construction is reduced by using orbital-specific virtuals (OSVs) as an intermediate step without spoiling the initial accuracy of the PNO method. Furthermore, a slower error convergence for charge-transfer states is analyzed and resolved by a numerical Laplace transformation during the PNO construction, so that an equally accurate treatment of local and charge-transfer excitations is achieved. With state-specific truncated PNO expansions, the eigenvalue problem is solved by combining the Davidson algorithm with deflation to project out roots that have already been determined and an automated refresh with a generation of new PNOs to achieve self-consistency of the PNO space. For a large test set, we found that truncation errors for PNO-CC2 excitation energies are only slightly larger than for PNO-CIS(D). The computational efficiency of PNO-CC2 is demonstrated for a large organic dye, where a reduction of the doubles space by a factor of more than 1000 is obtained compared to the canonical calculation. A compression of the doubles space by a factor 30 is achieved by a unified OSV space only. Moreover, calculations with the still preliminary PNO-CC2 implementation on a series of glycine oligomers revealed an early break even point with a canonical RI-CC2 implementation between 100 and 300 basis functions.
International Nuclear Information System (INIS)
Gori-Giorgi, Paola; Savin, Andreas
2006-01-01
The combination of density-functional theory with other approaches to the many-electron problem through the separation of the electron-electron interaction into a short-range and a long-range contribution is a promising method, which is raising more and more interest in recent years. In this work some properties of the corresponding correlation energy functionals are derived by studying the electron-electron coalescence condition for a modified (long-range-only) interaction. A general relation for the on-top (zero electron-electron distance) pair density is derived, and its usefulness is discussed with some examples. For the special case of the uniform electron gas, a simple parametrization of the on-top pair density for a long-range only interaction is presented and supported by calculations within the ''extended Overhauser model.'' The results of this work can be used to build self-interaction corrected short-range correlation energy functionals
Energy Technology Data Exchange (ETDEWEB)
Gorelik, M.L.; Shlomo, S. [National Research Nuclear University “MEPhI”, Moscow 115409 (Russian Federation); Cyclotron Institute, Texas A& M University, College Station, TX 77843 (United States); Tulupov, B.A. [National Research Nuclear University “MEPhI”, Moscow 115409 (Russian Federation); Institute for Nuclear Research, RAS, Moscow 117312 (Russian Federation); Urin, M.H., E-mail: urin@theor.mephi.ru [National Research Nuclear University “MEPhI”, Moscow 115409 (Russian Federation)
2016-11-15
The particle–hole dispersive optical model, developed recently, is applied to study properties of high-energy isoscalar monopole excitations in medium-heavy mass spherical nuclei. The energy-averaged strength functions of the isoscalar giant monopole resonance and its overtone in {sup 208}Pb are analyzed. In particular, we analyze the energy-averaged isoscalar monopole double transition density, the key quantity in the description of the hadron–nucleus inelastic scattering, and studied the validity of the factorization approximation using semi classical and microscopic one body transition densities, respectively, in calculating the cross sections for the excitation of isoscalar giant resonances by inelastic alpha scattering.
Energy Technology Data Exchange (ETDEWEB)
Sood, B S; Allawadhi, K L; Arora, S K [Punjabi Univ., Patiala (India). Nuclear Science Labs.
1982-02-15
The method developed for the determination of K/L shell photoionization cross sections in various elements, 39 <= Z <= 92, in the characteristic X-ray energy region using a gamma excited variable energy X-ray source has been used for the measurement of Lsub(III) subshell photoionization cross section in Pb, Th and U. The measurements are made at the K X-ray energies of Rb, Nb and Mo, since these are able to excite selectively the Lsub(III) subshells of Pb, Th and U, respectively. The results, when compared with theoretical calculations of Scofield, are found to agree within the uncertainties of determination.
DEFF Research Database (Denmark)
Ghiringhelli, G.; Piazzalunga, A.; Wang, X.
2009-01-01
of the 3d transition metals with unprecedented energy resolution, of the order of 100 meV for Mn, Ni and Cu. We present here some preliminary spectra on CuO, malachite, NiO, , MnO and . The dd excitations are very well resolved allowing accurate experimental evaluation of 3d state energy splitting. The low...
van Meer, R.; Gritsenko, O.V.; Baerends, E.J.
2014-01-01
In recent years, several benchmark studies on the performance of large sets of functionals in time-dependent density functional theory (TDDFT) calculations of excitation energies have been performed. The tested functionals do not approximate exact Kohn-Sham orbitals and orbital energies closely. We
Elioff, Michael S.; Wall, Mark C.; Lemoff, Andrew S.; Mullin, Amy S.
1999-03-01
Energy dependent studies of the collisional relaxation of highly vibrationally excited pyrazine through collisions with CO2 were performed for initial pyrazine energies Evib=31 000-35 000 cm-1. These studies are presented along with earlier results for pyrazine with Evib=36 000-41 000 cm-1. High-resolution transient IR laser absorption of individual CO2 (0000) rotational states (J=56-80) was used to investigate the magnitude and partitioning of energy gain into CO2 rotation and translation, which comprises the high energy tail of the energy transfer distribution function. Highly vibrationally excited pyrazine was prepared by absorption of pulsed UV light at seven wavelengths in the range λ=281-324 nm, followed by radiationless decay to pyrazine's ground electronic state. Nascent CO2 (0000) rotational populations were measured for each UV excitation wavelength and distributions of nascent recoil velocities for individual rotational states of CO2 (0000) were obtained from Doppler-broadened transient linewidth measurements. Measurements of energy transfer rate constants at each UV wavelength yield energy-dependent probabilities for collisions involving large ΔE values. These results reveal that the magnitude of large ΔE collisional energy gain in CO2 (0000) is fairly insensitive to the amount of vibrational energy in pyrazine for Evib=31 000-35 000 cm-1. A comparison with earlier studies on pyrazine with Evib=36 000-41 000 cm-1 indicates that the V→RT energy transfer increases both in magnitude and probability for Evib>36 000 cm-1. Implications of incomplete intramolecular vibrational relaxation, electronic state coupling, and isomerization barriers are discussed in light of these results.
Low-energy d-d excitations in MnO studied by resonant x-ray fluorescence spectroscopy
International Nuclear Information System (INIS)
Butorin, S.M.; Guo, J.; Magnuson, M.
1997-01-01
Resonant soft X-ray emission spectroscopy has been demonstrated to possess interesting abilities for studies of electronic structure in various systems, such as symmetry probing, alignment and polarization dependence, sensitivity to channel interference, etc. In the present abstract the authors focus on the feasibility of resonant soft X-ray emission to probe low energy excitations by means of resonant electronic X-ray Raman scattering. Resonant X-ray emission can be regarded as an inelastic scattering process where a system in the ground state is transferred to a low excited state via a virtual core excitation. The energy closeness to a core excitation of the exciting radiation enhances the (generally) low probability for inelastic scattering at these wavelengths. Therefore soft X-ray emission spectroscopy (in resonant electronic Raman mode) can be used to study low energy d-d excitations in transition metal systems. The involvement of the intermediate core state allows one to use the selection rules of X-ray emission, and the appearance of the elastically scattered line in the spectra provides the reference to the ground state
Low-energy d-d excitations in MnO studied by resonant x-ray fluorescence spectroscopy
Energy Technology Data Exchange (ETDEWEB)
Butorin, S.M.; Guo, J.; Magnuson, M. [Uppsala Univ. (Sweden)] [and others
1997-04-01
Resonant soft X-ray emission spectroscopy has been demonstrated to possess interesting abilities for studies of electronic structure in various systems, such as symmetry probing, alignment and polarization dependence, sensitivity to channel interference, etc. In the present abstract the authors focus on the feasibility of resonant soft X-ray emission to probe low energy excitations by means of resonant electronic X-ray Raman scattering. Resonant X-ray emission can be regarded as an inelastic scattering process where a system in the ground state is transferred to a low excited state via a virtual core excitation. The energy closeness to a core excitation of the exciting radiation enhances the (generally) low probability for inelastic scattering at these wavelengths. Therefore soft X-ray emission spectroscopy (in resonant electronic Raman mode) can be used to study low energy d-d excitations in transition metal systems. The involvement of the intermediate core state allows one to use the selection rules of X-ray emission, and the appearance of the elastically scattered line in the spectra provides the reference to the ground state.
Pulsed power inductive energy storage in the microsecond range
International Nuclear Information System (INIS)
Rix, W.; Miller, A.R.; Thompson, J.; Waisman, E.; Wilkinson, M.; Wilson, A.
1993-01-01
During the past five years Maxwell has developed a series of inductive energy storage (IES) pulsed power generators; ACE 1, ACE 2, ACE 3, and ACE 4, to drive electron-beam loads. They are all based on a plasma opening switch (POS) contained in a single vacuum envelope operating at conduction times of around one microsecond. They all employ fast capacitor bank technology to match this conduction time without intermediate power conditioning. Oil or air filled transmission lines transfer capacitor bank energy to a vacuum section where the final pulse compression is accomplished. Development of the ACE series is described, emphasizing capacitor bank and the opening switch technology for delivering high voltage, multimegampere pulses to electron beam loads
Aspects of kinematical coincidence measurements of excitation energy division in damped reactions
International Nuclear Information System (INIS)
Toke, J.; Schroeder, W.U.; Huizenga, J.R.; Rochester Univ., NY
1990-01-01
It is shown that the finite resolution inherent in the kinematical coincidence method leads to systematic errors in the deduced (primary) physical quantities if the latter are calculated based on mass and linear momentum conservation equations alone. As an example, application of this method for measuring excitation energy of the fragments from damped reactions is reviewed. In such a case, finite resolution effects generate significant instrumental, or 'background' correlations between the physical quantities reconstructed in a straightforward fashion, hence, if not accounted for, they may lead to the qualitative misinterpretation of the data. Experimental measures are discussed which appear necessary in order to ensure proper accuracy of the finite resolution corrections. An alternative method of data analysis is presented which is much less susceptible to the finite resolution effects discussed. (orig.)
Energy dispersive soft X-ray fluorescence analysis by radioisotopic α-particle excitation
International Nuclear Information System (INIS)
Robertson, R.
1977-01-01
A Si(Li) X-ray detector system and 210 Po α-particle excitation source are combined to form a spectrometer for low energy X-rays. Its response in terms of Ksub(α) X-ray rate is shown for thick targets of elements from fluorine to copper. Potential applications of the equipment to useful quantitative elemental analysis of geological, biological and organic materials are explored. The results of analyses for oxygen and silicon in rocks and potassium in vegetation samples are included. A semi-empirical method of correcting for absorption and enhancement effects is employed. This is based upon X-ray production and photon absorption cross-sections taken from the literature and upon a minimal number of experimentally derived coefficients. (Auth.)
Energy Technology Data Exchange (ETDEWEB)
Chen, T., E-mail: tao.chen@fysik.su.se, E-mail: henning@fysik.su.se; Gatchell, M.; Stockett, M. H.; Schmidt, H. T.; Cederquist, H.; Zettergren, H., E-mail: tao.chen@fysik.su.se, E-mail: henning@fysik.su.se [Department of Physics, Stockholm University, S-106 91 Stockholm (Sweden); Delaunay, R.; Rousseau, P.; Adoui, L. [CIMAP, UMR 6252, CEA/CNRS/ENSICAEN/Université de Caen Basse-Normandie, bd Henri Becquerel, BP 5133, F-14070 Caen cedex 05 (France); Université de Caen Basse-Normandie, Esplanade de la Paix, F-14032 Caen (France); Domaracka, A.; Huber, B. A. [CIMAP, UMR 6252, CEA/CNRS/ENSICAEN/Université de Caen Basse-Normandie, bd Henri Becquerel, BP 5133, F-14070 Caen cedex 05 (France); Micelotta, E. R. [Université Paris Sud, Institut d’Astrophysique Spatiale, UMR 8617, 91405 Orsay (France); Tielens, A. G. G. M. [Leiden Observatory, Leiden University, P.O. Box 9513, 2300 RA Leiden (Netherlands)
2015-04-14
We have investigated the effectiveness of molecular hydrogen (H{sub 2}) formation from Polycyclic Aromatic Hydrocarbons (PAHs) which are internally heated by collisions with keV ions. The present and earlier experimental results are analyzed in view of molecular structure calculations and a simple collision model. We estimate that H{sub 2} formation becomes important for internal PAH temperatures exceeding about 2200 K, regardless of the PAH size and the excitation agent. This suggests that keV ions may effectively induce such reactions, while they are unlikely due to, e.g., absorption of single photons with energies below the Lyman limit. The present analysis also suggests that H{sub 2} emission is correlated with multi-fragmentation processes, which means that the [PAH-2H]{sup +} peak intensities in the mass spectra may not be used for estimating H{sub 2}-formation rates.
Mean excitation energy of polystyrene extracted from proton-stopping-power measurements
International Nuclear Information System (INIS)
Porter, L.E.
1980-01-01
The measured stopping power of polystyrene for 2.2- to 5.9-MeV protons has been analyzed with the Bloch projectile-z 4 correction term and a modified low-velocity projectile-z 3 term included in the Bethe-Bloch formula. When the full-strength Walske K-shell correction was utilized, the mean excitation energy corresponding to the best fit of the measurements was (71.1 +- 1.8) eV. This result was obtained for a value of the free parameter of the low-velocity projectile-z 3 effect formalism of 1.90 +- 0.05, whether or not a Walske L-shell correction was included
International Nuclear Information System (INIS)
Fink, R.F.; Pfister, J.; Schneider, A.; Zhao, H.; Engels, B.
2008-01-01
We present new, generally applicable protocols for the computation of the coupling parameter, J, of excitation energy transfer with quantum chemical ab initio methods. The protocols allow to select the degree of approximation and computational demand such that they are applicable for realistic systems and still allow to control the quality of the approach. We demonstrate the capabilities of the different protocols using the CO dimer as a first example. Correlation effects are found to scale J by a factor of about 0.7 which is in good agreement to earlier results obtained for the ethene dimer. The various levels of the protocol allow to assess the influence of ionic configurations and the polarisation within the dimer. Further, the interplay between the Foerster and Dexter contribution to J is investigated. The computations also show error compensation within approximations that are widely used for extended systems as in particular the transition density cube method
International Nuclear Information System (INIS)
Barbatti, M.; Paier, J.; Lischka, H.
2004-01-01
Multireference configuration interaction with singles and doubles (MR-CISD) calculations have been performed for the optimization of conical intersections and stationary points on the ethylene excited-state energy surfaces using recently developed methods for the computation of analytic gradients and nonadiabatic coupling terms. Basis set dependence and the effect of various choices of reference spaces for the MR-CISD calculations have been investigated. The crossing seam between the S 0 and S 1 states has been explored in detail. This seam connects all conical intersections presently known for ethylene. Major emphasis has been laid on the hydrogen-migration path. Starting in the V state of twisted-orthogonal ethylene, a barrierless path to ethylidene was found. The feasibility of ethylidene formation will be important for the explanation of the relative yield of cis and trans H 2 elimination
Nuclei far from stability. Individual and collective excitations at low energy
International Nuclear Information System (INIS)
Meyer, M.
1984-01-01
The low energy structure of exotic nuclei is discussed in terms of self-consistent microscopic models. The experimental striking features of the spectroscopy of these nuclei are briefly surveyed and the schematic steps performed to obtain from effective N-N interactions their spectroscopic properties are presented. Their saturation and deformation properties are given by the Hartree-Fock approximation (HF). Then it is shown how to describe the dynamics of even-even exotic nuclei excited states by solving the complete Bohr Hamiltonian, built microscopically using the HF approximation and the adiabatic limit (and its derivatives) of the time-dependent HF approximation (ATDHF). The structure of odd and doubly odd nuclei is discussed in the framework of the unified model, ie the microscopic rotor + quasiparticles model. Finally possible future directions of experimental research concerning exotic nuclei are described and improvements or new theoretical approaches discussed [fr
Study on germ toxicity of exciting energy resource 147Pm of fluorescent paint
International Nuclear Information System (INIS)
Zhu Shoupeng; Lun Minyue; Tao Feng
1993-02-01
The germ toxicity of exciting energy resource 147 Pm of fluorescent paint was studied. It was shown that the placenta was a barrier for 147 Pm entering into the fetus. The retention T 1/2 was 105 days in testes. The retention value of 147 Pm in testis was high and hardly to excrete. The results showed that 147 Pm can induce abnormal sperms, most of them were non-hock sperms. The chromosome aberrations in germ cells also can be induced. Among the type of chromosome aberrations of spermatogonia, chromatid breakage was predominant. The 147 Pm can cause the chromosome fragment and translocations of primary spermatocytes, and increasing of lethality. The dominant skeletal aberrations in offspring is proportional to the accumulated radioactivity of 147 Pm in tests
Energy levels of the single excited states in NaI and Na-like ions
International Nuclear Information System (INIS)
El-Sherbini, T.M.; Wahby, A.S.
1987-08-01
Energy levels of the single excited 1s 2 2s 2 2p 6 ns( 2 S), 1s 2 2s 2 2p 6 mp( 2 P), 1s 2 2s 2 2p 6 md( 2 D) and 1s 2 2s 2 2p 6 nf( 2 F); n=4-7, m=3-6 states for NaI and Na-like ions are calculated using the one configuration Hartree-Fock method. Good agreement is obtained between our results for the higher members of the NaI sequence and previous data from photo-absorption and beam foil experiments. (author). 11 refs, 3 figs, 9 tabs
Energy Technology Data Exchange (ETDEWEB)
Fink, R.F. [University of Wuerzburg, Institute of Organic Chemistry, Am Hubland, D-97074 Wuerzburg (Germany)], E-mail: reinhold.fink@rub.de; Pfister, J.; Schneider, A.; Zhao, H.; Engels, B. [University of Wuerzburg, Institute of Organic Chemistry, Am Hubland, D-97074 Wuerzburg (Germany)
2008-01-29
We present new, generally applicable protocols for the computation of the coupling parameter, J, of excitation energy transfer with quantum chemical ab initio methods. The protocols allow to select the degree of approximation and computational demand such that they are applicable for realistic systems and still allow to control the quality of the approach. We demonstrate the capabilities of the different protocols using the CO dimer as a first example. Correlation effects are found to scale J by a factor of about 0.7 which is in good agreement to earlier results obtained for the ethene dimer. The various levels of the protocol allow to assess the influence of ionic configurations and the polarisation within the dimer. Further, the interplay between the Foerster and Dexter contribution to J is investigated. The computations also show error compensation within approximations that are widely used for extended systems as in particular the transition density cube method.
Sokolowski-Tinten, K; Shen, X; Zheng, Q; Chase, T; Coffee, R; Jerman, M; Li, R K; Ligges, M; Makasyuk, I; Mo, M; Reid, A H; Rethfeld, B; Vecchione, T; Weathersby, S P; Dürr, H A; Wang, X J
2017-09-01
We apply time-resolved MeV electron diffraction to study the electron-lattice energy relaxation in thin film Au-insulator heterostructures. Through precise measurements of the transient Debye-Waller-factor, the mean-square atomic displacement is directly determined, which allows to quantitatively follow the temporal evolution of the lattice temperature after short pulse laser excitation. Data obtained over an extended range of laser fluences reveal an increased relaxation rate when the film thickness is reduced or the Au-film is capped with an additional insulator top-layer. This behavior is attributed to a cross-interfacial coupling of excited electrons in the Au film to phonons in the adjacent insulator layer(s). Analysis of the data using the two-temperature-model taking explicitly into account the additional energy loss at the interface(s) allows to deduce the relative strength of the two relaxation channels.
Directory of Open Access Journals (Sweden)
M. Jäckl
2017-04-01
Full Text Available Optical tools are promising for spin-wave generation because of the possibilities of ultrafast manipulation and local excitation. However, a single laser pulse can inject spin waves (SWs only with a broad frequency spectrum, resulting in short propagation distances and low wave amplitudes. Here, we excite a magnetic garnet film by a train of fs-laser pulses with a 1-GHz repetition rate so that the pulse separation is shorter than the decay time of magnetic modes, which allows us to achieve a collective impact on the magnetization and establish a quasistationary source of spin waves, namely, a coherent accumulation of magnons (“magnon cloud”. This approach has several appealing features: (i The magnon source is tunable, (ii the SW amplitude can be significantly enhanced, (iii the SW spectrum is quite narrow, providing long-distance propagation, (iv the periodic pumping results in an almost constant-in-time SW amplitude for the distances larger than 20 μm away from the source, and (v the SW emission shows pronounced directionality. These results expand the capabilities of ultrafast coherent optical control of magnetization and pave the way for applications in data processing, including the quantum regime. The quasistationary magnon accumulation might also be of interest for applications in magnon Bose-Einstein condensates.
Kilovoltage energy imaging with a radiotherapy linac with a continuously variable energy range.
Roberts, D A; Hansen, V N; Thompson, M G; Poludniowski, G; Niven, A; Seco, J; Evans, P M
2012-03-01
In this paper, the effect on image quality of significantly reducing the primary electron energy of a radiotherapy accelerator is investigated using a novel waveguide test piece. The waveguide contains a novel variable coupling device (rotovane), allowing for a wide continuously variable energy range of between 1.4 and 9 MeV suitable for both imaging and therapy. Imaging at linac accelerating potentials close to 1 MV was investigated experimentally and via Monte Carlo simulations. An imaging beam line was designed, and planar and cone beam computed tomography images were obtained to enable qualitative and quantitative comparisons with kilovoltage and megavoltage imaging systems. The imaging beam had an electron energy of 1.4 MeV, which was incident on a water cooled electron window consisting of stainless steel, a 5 mm carbon electron absorber and 2.5 mm aluminium filtration. Images were acquired with an amorphous silicon detector sensitive to diagnostic x-ray energies. The x-ray beam had an average energy of 220 keV and half value layer of 5.9 mm of copper. Cone beam CT images with the same contrast to noise ratio as a gantry mounted kilovoltage imaging system were obtained with doses as low as 2 cGy. This dose is equivalent to a single 6 MV portal image. While 12 times higher than a 100 kVp CBCT system (Elekta XVI), this dose is 140 times lower than a 6 MV cone beam imaging system and 6 times lower than previously published LowZ imaging beams operating at higher (4-5 MeV) energies. The novel coupling device provides for a wide range of electron energies that are suitable for kilovoltage quality imaging and therapy. The imaging system provides high contrast images from the therapy portal at low dose, approaching that of gantry mounted kilovoltage x-ray systems. Additionally, the system provides low dose imaging directly from the therapy portal, potentially allowing for target tracking during radiotherapy treatment. There is the scope with such a tuneable system
Electron beam absorption in solid and in water phantoms: depth scaling and energy-range relations
International Nuclear Information System (INIS)
Grosswendt, B.; Roos, M.
1989-01-01
In electron dosimetry energy parameters are used with values evaluated from ranges in water. The electron ranges in water may be deduced from ranges measured in solid phantoms. Several procedures recommended by national and international organisations differ both in the scaling of the ranges and in the energy-range relations for water. Using the Monte Carlo method the application of different procedures for electron energies below 10 MeV is studied for different phantom materials. It is shown that deviations in the range scaling and in the energy-range relations for water may accumulate to give energy errors of several per cent. In consequence energy-range relations are deduced for several solid phantom materials which enable a single-step energy determination. (author)
Analytical Energy Gradients for Excited-State Coupled-Cluster Methods
Wladyslawski, Mark; Nooijen, Marcel
The equation-of-motion coupled-cluster (EOM-CC) and similarity transformed equation-of-motion coupled-cluster (STEOM-CC) methods have been firmly established as accurate and routinely applicable extensions of single-reference coupled-cluster theory to describe electronically excited states. An overview of these methods is provided, with emphasis on the many-body similarity transform concept that is the key to a rationalization of their accuracy. The main topic of the paper is the derivation of analytical energy gradients for such non-variational electronic structure approaches, with an ultimate focus on obtaining their detailed algebraic working equations. A general theoretical framework using Lagrange's method of undetermined multipliers is presented, and the method is applied to formulate the EOM-CC and STEOM-CC gradients in abstract operator terms, following the previous work in [P.G. Szalay, Int. J. Quantum Chem. 55 (1995) 151] and [S.R. Gwaltney, R.J. Bartlett, M. Nooijen, J. Chem. Phys. 111 (1999) 58]. Moreover, the systematics of the Lagrange multiplier approach is suitable for automation by computer, enabling the derivation of the detailed derivative equations through a standardized and direct procedure. To this end, we have developed the SMART (Symbolic Manipulation and Regrouping of Tensors) package of automated symbolic algebra routines, written in the Mathematica programming language. The SMART toolkit provides the means to expand, differentiate, and simplify equations by manipulation of the detailed algebraic tensor expressions directly. The Lagrangian multiplier formulation establishes a uniform strategy to perform the automated derivation in a standardized manner: A Lagrange multiplier functional is constructed from the explicit algebraic equations that define the energy in the electronic method; the energy functional is then made fully variational with respect to all of its parameters, and the symbolic differentiations directly yield the explicit
Excitation functions of proton induced reactions on {sup nat}Fe in the energy region up to 45 MeV
Energy Technology Data Exchange (ETDEWEB)
Kim, Kwangsoo [Department of Physics, Kyungpook National University, Daegu 702-701 (Korea, Republic of); Khandaker, Mayeen Uddin [Department of Physics, Kyungpook National University, Daegu 702-701 (Korea, Republic of); Department of Physics, University of Malaya, 50603 Kuala Lumpur (Malaysia); Naik, Haladhara [Department of Physics, Kyungpook National University, Daegu 702-701 (Korea, Republic of); Radiochemistry Division, Bhabha Atomic Research Center, Trombay, Mumbai 400085 (India); Kim, Guinyun, E-mail: gnkim@knu.ac.kr [Department of Physics, Kyungpook National University, Daegu 702-701 (Korea, Republic of)
2014-03-01
The excitation functions of various reaction products such as {sup 55,56,57}Co, {sup 52}Fe, {sup 52,54}Mn, and {sup 51}Cr in the {sup nat}Fe(p, x) reactions were measured by the stacked-foil activation technique in the energy range between their respective reaction threshold and 45 MeV at the MC-50 cyclotron of the Korean Institute of Radiological and Medical Sciences, Korea. The present experimental data were compared with the existing literature data. It was found that excitation function of {sup 56,57}Co and {sup 51}Cr from the {sup nat}Fe(p, x) reaction are in agreement with the literature data. However, the cross-sections for {sup nat}Fe(p, x){sup 52}Fe reactions are lower and those for {sup nat}Fe(p, x){sup 52}Mn and {sup nat}Fe(p, x){sup 54}Mn reactions are higher than the literature data. The reaction cross-sections of the above mentioned reaction products were also compared with those from the TENDL-2012 library based on the TALYS-1.4 program as a function of proton energy, which was reproduced the trend of the excitation functions of the experimental {sup nat}Fe(p, x) reaction cross-section. The integral yields for thick target of the investigated radionuclides were calculated from the excitation function.
International Nuclear Information System (INIS)
Stryganyuk, G.; Shalapska, T.; Voloshinovskii, A.; Gektin, A.; Krasnikov, A.; Zazubovich, S.
2011-01-01
Spectral-kinetic characteristics of Gd 3+ and Ce 3+ luminescence from a series of Ce 3+ -doped alkali gadolinium phosphates of MGdP 4 O 12 type (M=Li, Na, Cs) have been studied within 4.2-300 K temperature range using time-resolved luminescence spectroscopy techniques. The processes of energy migration along the Gd 3+ sub-lattice and energy transfer between the Gd 3+ and Ce 3+ ions have been investigated. Peculiarities of these processes have been compared for MGdP 4 O 12 phosphate hosts with different alkali metal ions. A contribution of different levels from the 6 P j multiplet of the lowest Gd 3+ excited state into the energy migration and transfer processes has been clarified. The phonon-assisted occupation of high-energy 6 P 5/2,3/2 levels by Gd 3+ in the excited 6 P j state has been revealed as a shift of Gd 3+6 P j → 8 S 7/2 emission into the short-wavelength spectral range upon the temperature increase. The relaxation of excited Gd 3+ via phonon-assisted population of Gd 3+6 P 5/2 level (next higher one to the lowest excited 6 P 7/2 ) is supposed to be responsible for the rise in probability of energy migration within the Gd 3+ sub-lattice initiating the Gd 3+ →Ce 3+ energy transfer at T 3+ →Ce 3+ energy transfer at T>150 K is explained by the increase in probability of Gd 3+ relaxation into the highest 6 P 3/2 level of the 6 P j multiplet. An efficient reversed Ce 3+ →Gd 3+ energy transfer has been revealed for the studied phosphates at 4.2 K. - Highlights: →We investigate the Gd 3+ -Ce 3+ energy transfer in alkali gadolinium phosphates. → Thermal population of Gd 3+6 P 5/2 level improves migration along the Gd sub-lattice. → Increasing overlap of Gd 3+ and Ce 3+ states enhances the Gd 3+ -Ce 3+ energy transfer. → In LiGdP 4 O 12 :Ce and NaGdP 4 O 12 :Ce an efficient Ce 3+ -Gd 3+ transfer occurs at 4-300 K. → An effective reverse Gd 3+ -Ce 3+ energy transfer becomes possible at T>150 K.
Regeta, Khrystyna; Bannwarth, Christoph; Grimme, Stefan; Allan, Michael
2015-06-28
The technique of low energy (0-30 eV) electron impact spectroscopy, originally developed for gas phase molecules, is applied to room temperature ionic liquids (IL). Electron energy loss (EEL) spectra recorded near threshold, by collecting 0-2 eV electrons, are largely continuous, assigned to excitation of a quasi-continuum of high overtones and combination vibrations of low-frequency modes. EEL spectra recorded by collecting 10 eV electrons show predominantly discrete vibrational and electronic bands. The vibrational energy-loss spectra correspond well to IR spectra except for a broadening (∼0.04 eV) caused by the liquid surroundings, and enhanced overtone activity indicating a contribution from resonant excitation mechanism. The spectra of four representative ILs were recorded in the energy range of electronic excitations and compared to density functional theory multireference configuration interaction (DFT/MRCI) calculations, with good agreement. The spectra up to about 8 eV are dominated by π-π* transitions of the aromatic cations. The lowest bands were identified as triplet states. The spectral region 2-8 eV was empty in the case of a cation without π orbitals. The EEL spectrum of a saturated solution of methylene green in an IL band showed the methylene green EEL band at 2 eV, indicating that ILs may be used as a host to study nonvolatile compounds by this technique in the future.
International Nuclear Information System (INIS)
Boo, Bong Hyun; Koyano, Inosuke
2002-01-01
Dissociative photoionization of an interhalogen molecule, iodine monobromide (IBr), spanning the I(4d) and the Br(3d) inner-shell excitation/ionization regions has been studied by using time-of-flight (TOF) mass spectrometry coupled to synchrotron radiation in the range of 60 ∼ 133 eV. The total and the individual photoion yields have been recorded as functions of the photon energy. Here, a giant shape resonance has been observed owing to the I(4d 10 ) →I(4d 9 εf) transition, the transition probability for which outweighs that for the Br(3d 10 ) →Br(3d 9 εf) excitation. In addition to the huge resonance, discrete resonances owing to the Br(3d) -1 IBr(4pσ + ) and the Br(3d -1 )Br(5p) transitions, with very weak intensities, are observed at 70.5 and 73.6 eV and have spin-orbit splittings of = 1.0 and = 0.9 eV, respectively. The dissociation processes of singly and doubly charged parent ions have also been evaluated from the variations of the individual ion and photoion-photoion coincidence (PIPICO) yields with the photon energy. Below the Br(3d) threshold, including the Br(3d) discrete excitation region, 60 + and I 2+ ions are exclusively formed with a trace number of Br + ions. Slightly above the Br(3d) threshold, more specifically at 77.5 eV, however, photoionization events leading to the formations of Br + and Br 2- prevail. At higher energies beyond the Br(3d) threshold, 78 + and I 2+ turn out to exceed again those for Br + and Br 2+ , respectively. Over the entire energy range examined, a remarkable biased charge spread in dissociative photoionization events is observed, presumably reflecting the fact that charge localized mostly in the excited atoms relevant to the specific inner-shell excitation, which can be accounted for mainly by a two-step decay process via a fast dissociation followed by autoionization upon vuv absorption
Charge transfer and excitation in high-energy ion-atom collisions
International Nuclear Information System (INIS)
Schlachter, A.S.; Berkner, K.H.; McDonald, R.J.
1986-11-01
Coincidence measurements of charge transfer and simultaneous projectile electron excitation provide insight into correlated two-electron processes in energetic ion-atom collisions. Projectile excitation and electron capture can occur simultaneously in a collision of a highly charged ion with a target atom; this process is called resonant transfer and excitation (RTE). The intermediate excited state which is thus formed can subsequently decay by photon emission or by Auger-electron emission. Results are shown for RTE in both the K shell of Ca ions and the L shell of Nb ions, for simultaneous projectile electron loss and excitation, and for the effect of RTE on electron capture
International Nuclear Information System (INIS)
Gil, T.J.; McCurdy, C.W.; Rescigno, T.N.; Lengsfield, B.H. III
1994-01-01
The authors are reporting results of ab-initio calculations of electron-impact excitation of water and methane occurring at scattering energies up to 60 eV. The authors consider dissociative excited states of both systems since the understanding of their chemistry has considerable importance in plasma technology and atmospheric research. In the case of methane the authors are dealing with the promotion of a valence electron into Rydberg orbitals, while in water the excited states have one electron in an antibonding unoccupied valence orbital and support Feshbach resonances. The authors discuss issues related to convergence of the close-coupling expansion in the case of Rydberg excitation, where the authors have coupled up to 16 channels. The practical realization of the calculation within the framework of the complex Kohn variational principle represents merging of quantum chemistry and quantum scattering theory and is also discussed
A piezoelectric energy harvester for broadband rotational excitation using buckled beam
Directory of Open Access Journals (Sweden)
Zhengqiu Xie
2018-01-01
Full Text Available This paper proposes a rotational energy harvester using a piezoelectric bistable buckled beam to harvest low-speed rotational energy. The proposed harvester consists of a piezoelectric buckled beam with a center magnet, and a rotary magnet pair with opposite magnetic poles mounted on a revolving host. The magnetic plucking is used to harvest the angular kinetic energy of the host. The nonlinear snap-through mechanism is utilized to improve the vibration displacement and output voltage of the piezoelectric layer over a wide rotation frequency range. Theoretical simulation and experimental results show that the proposed energy harvester can yield a stable average output power ranging between 6.91-48.01 μW over a rotation frequency range of 1-14 Hz across a resistance load of 110 kΩ. Furthermore, dual attraction magnets were employed to overcome the suppression phenomenon at higher frequencies, which yields a broadband and flat frequency response over 6-14 Hz with the output power reaching 42.19-65.44 μW, demonstrating the great potential of the bistable buckled beam for wideband rotation motion energy harvesting.
A piezoelectric energy harvester for broadband rotational excitation using buckled beam
Xie, Zhengqiu; Kitio Kwuimy, C. A.; Wang, Zhiguo; Huang, Wenbin
2018-01-01
This paper proposes a rotational energy harvester using a piezoelectric bistable buckled beam to harvest low-speed rotational energy. The proposed harvester consists of a piezoelectric buckled beam with a center magnet, and a rotary magnet pair with opposite magnetic poles mounted on a revolving host. The magnetic plucking is used to harvest the angular kinetic energy of the host. The nonlinear snap-through mechanism is utilized to improve the vibration displacement and output voltage of the piezoelectric layer over a wide rotation frequency range. Theoretical simulation and experimental results show that the proposed energy harvester can yield a stable average output power ranging between 6.91-48.01 μW over a rotation frequency range of 1-14 Hz across a resistance load of 110 kΩ. Furthermore, dual attraction magnets were employed to overcome the suppression phenomenon at higher frequencies, which yields a broadband and flat frequency response over 6-14 Hz with the output power reaching 42.19-65.44 μW, demonstrating the great potential of the bistable buckled beam for wideband rotation motion energy harvesting.
Bellemans, Aurélie; Parente, Alessandro; Magin, Thierry
2018-04-01
The present work introduces a novel approach for obtaining reduced chemistry representations of large kinetic mechanisms in strong non-equilibrium conditions. The need for accurate reduced-order models arises from compression of large ab initio quantum chemistry databases for their use in fluid codes. The method presented in this paper builds on existing physics-based strategies and proposes a new approach based on the combination of a simple coarse grain model with Principal Component Analysis (PCA). The internal energy levels of the chemical species are regrouped in distinct energy groups with a uniform lumping technique. Following the philosophy of machine learning, PCA is applied on the training data provided by the coarse grain model to find an optimally reduced representation of the full kinetic mechanism. Compared to recently published complex lumping strategies, no expert judgment is required before the application of PCA. In this work, we will demonstrate the benefits of the combined approach, stressing its simplicity, reliability, and accuracy. The technique is demonstrated by reducing the complex quantum N2(g+1Σ) -N(S4u ) database for studying molecular dissociation and excitation in strong non-equilibrium. Starting from detailed kinetics, an accurate reduced model is developed and used to study non-equilibrium properties of the N2(g+1Σ) -N(S4u ) system in shock relaxation simulations.
Rate for energy transfer from excited cyclohexane to nitrous oxide in the liquid phase
International Nuclear Information System (INIS)
Wada, T.; Hatano, Y.
1975-01-01
Pure liquid cyclohexane and cyclohexane solutions of nitrous oxide have been photolyzed at 163 nm. The quantum yield of the product hydrogen in the photolysis of pure cyclohexane is found to be 1.0. The addition of nitrous oxide results in the reduction in the yield of hydrogen and in the formation of nitrogen. The decrement of the hydrogen yield is approximately equal to the increment of the nitrogen yield. About 40 percent of the hydrogen yield in pure cyclohexane is found to be produced through a path which is not affected by the addition of nitrous oxide. The effect of the addition of nitrous oxide is attributed to energy transfer from excited cyclohexane to nitrous oxide with the rate constant of k = 1.0 x 10 11 M -1 sec -1 (at 15 0 C). This value is about a factor of 10 larger than that expected as for diffusion-controlled rate. A contribution of the energy transfer process to the formation of nitrogen in the radiolysis of cyclohexane solutions of nitrous oxide has also been discussed. (auth)
Power Management of Islanded Self-Excited Induction Generator Reinforced by Energy Storage Systems
Directory of Open Access Journals (Sweden)
Nachat N. Nasser
2018-02-01
Full Text Available Self-Excited Induction Generators (SEIGs, e.g., Small-Scale Embedded wind generation, are increasingly used in electricity distribution networks. The operational stability of stand-alone SEIG is constrained by the local load conditions: stability can be achieved by maintaining the load’s active and reactive power at optimal values. Changes in power demand are dependent on customers’ requirements, and any deviation from the pre-calculated optimum setting will affect a machine’s operating voltage and frequency. This paper presents an investigation of the operation of the SEIG in islanding mode of operation under different load conditions, with the aid of batteries as an energy storage source. In this research a current-controlled voltage-source converter is proposed to regulate the power exchange between a direct current (DC energy storage source and an alternating current (AC grid, the converter’s controller is driven by any variation between machine capability and load demand. In order to prolong the system stability when the battery reaches its operation constraints, it is recommended that an ancillary generator and a dummy local load be embedded in the system. The results show the robustness and operability of the proposed system in the islanding mode of the SEIG under different load conditions.
General theory of excitation energy transfer in donor-mediator-acceptor systems.
Kimura, Akihiro
2009-04-21
General theory of the excitation energy transfer (EET) in the case of donor-mediator-acceptor system was constructed by using generalized master equation (GME). In this theory, we consider the direct and indirect transitions in the EET consistently. Hence, our theory includes the quantum mechanical interference between the direct and indirect transitions automatically. Memory functions in the GME were expressed by the overlap integrals among the time-dependent emission spectrum of the donor, the absorption spectrum of the mediator, the time-dependent emission spectrum of the mediator, and the absorption spectrum of the acceptor. In the Markov limit of the memory functions, we obtained the rate of EET which consists of three terms due to the direct transition, the indirect transition, and the interference between them. We found that the interference works effectively in the limit of slow thermalization at the intermediate state. The formula of EET rate in this limit was expressed by the convolution of the EET interaction and optical spectra. The interference effect strongly depends on the width of the absorption spectrum of mediator molecule and the energy gap between the donor and the mediator molecules.
A coherent modified Redfield theory for excitation energy transfer in molecular aggregates
Energy Technology Data Exchange (ETDEWEB)
Hwang-Fu, Yu-Hsien; Chen, Wei; Cheng, Yuan-Chung, E-mail: yuanchung@ntu.edu.tw
2015-02-02
Highlights: • A CMRT method for coherent energy transfer in molecular aggregates was developed. • Applicability of the method was verified in two-site systems with various parameters. • CMRT accurately describes population dynamics in the FMO-complex. • The method is accurate in a large parameter space and computationally efficient. - Abstract: Excitation energy transfer (EET) is crucial in photosynthetic light harvesting, and quantum coherence has been recently proven to be a ubiquitous phenomenon in photosynthetic EET. In this work, we derive a coherent modified Redfield theory (CMRT) that generalizes the modified Redfield theory to treat coherence dynamics. We apply the CMRT method to simulate the EET in a dimer system and compare the results with those obtained from numerically exact path integral calculations. The comparison shows that CMRT provides excellent computational efficiency and accuracy within a large EET parameter space. Furthermore, we simulate the EET dynamics in the FMO complex at 77 K using CMRT. The results show pronounced non-Markovian effects and long-lasting coherences in the ultrafast EET, in excellent agreement with calculations using the hierarchy equation of motion approach. In summary, we have successfully developed a simple yet powerful framework for coherent EET dynamics in photosynthetic systems and organic materials.
YIELDS OF IONS AND EXCITED STATES IN NONPOLAR LIQUIDS EXPOSED TO X-RAYS OF 1 TO 30 KEV ENERGY
International Nuclear Information System (INIS)
HOLROYD, R.A.
1999-01-01
When x-rays from a synchrotron source are absorbed in a liquid, the x-ray energy (E x ) is converted by the photoelectric effect into the kinetic energy of the electrons released. For hydrocarbons, absorption by the K-electrons of carbon dominates. Thus the energy of the photoelectron (E pe ) is E x -E b , where E b is the K-shell binding energy of carbon. Additional electrons with energy equal to E b is released in the Auger process that fills the hole in the K-shell. These energetic electrons will produce many ionizations, excitations and products. The consequences of the high density of ionizations and excitations along the track of the photoelectron and special effects near the K-edge are examined here
Institute of Scientific and Technical Information of China (English)
YE Wei; CHEN Na
2004-01-01
Isospin effects on particle emission of fissioning isobaric sources 202Fr, 202po, 202Tl and isotopic sources 189,202,212Po, and its dependence on the excitation energy are studied via Smoluchowski equations. It is shown that with increasing the isospin of fissioning systems, charged-particle emission is not sensitive to the strength of nuclear dissipation. In addition, we have found that increasing the excitation energy not only increases the influence of nuclear dissipation on particle emission but also greatly enhances the sensitivity of the emission of pre-scission neutrons or charged particles to the isospin of the system. Therefore, in order to extract dissipation strength more accurately by taking light particle multiplicities it is important to choose both a highly excited compound nucleus and a proper kind of particles for systems with different isospins.
Li, Chen; Lu, Jianfeng; Yang, Weitao
2015-12-14
We develop the gentlest ascent dynamics for Kohn-Sham density functional theory to search for the index-1 saddle points on the energy landscape of the Kohn-Sham density functionals. These stationary solutions correspond to excited states in the ground state functionals. As shown by various examples, the first excited states of many chemical systems are given by these index-1 saddle points. Our novel approach provides an alternative, more robust way to obtain these excited states, compared with the widely used ΔSCF approach. The method can be easily generalized to target higher index saddle points. Our results also reveal the physical interest and relevance of studying the Kohn-Sham energy landscape.
Inner-shell excitation in heavy ion collisions up to intermediate incident energies
International Nuclear Information System (INIS)
Reus, T. de.
1987-04-01
Electronic excitations in collisions of very heavy ions with a total nuclear charge Z greater than 1/α ≅ 137 at bombarding energies reaching from 3.6 MeV/n up to 100 MeV/n are the subject of this thesis. The dynamical behaviour of the electron-positron-field is described within a semiclassical model, which is reviewed and extended to include electronic interactions via a mean field. A detailed comparison with experimental data of K-vacancy formation, δ-electron and positron emission shows an improved agreement compared with former calculations. Structures in spectra of positrons emitted in sub- and supercritical collision are discussed in two respects: Firstly as a signal of the vacuum decay in supercritical electromagnetic fields which evolve in the vicinity of long living giant nuclear molecules. Secondly as an atomic effect, which might be related to an instaneous formation of molecular 1sσ- and 2p 1/2 σ- levels. However, beyond this speculation the emission spectra of electrons and positrons in deep inelastic reactions have proven to be a powerful tool for measuring nuclear reaction or delay times in the order of 10 -21 s. This property was transfered to the domain of intermediate energy collisions. In first order perturbation theory we derived a scaling law, exhibiting how nuclear stopping times could be extracted from the emission spectra of high energetic δ-electrons. Quantitative calculations within a coupled channel code have been carried out for the system Pb+Pb, yielding cross sections of up to 20 nb for the emission of electrons with a kinetic energy of 50 MeV in 60 MeV/n-collisions. (orig./HSI)
DEFF Research Database (Denmark)
Cornaton, Y.; Stoyanova, A.; Jensen, Hans Jørgen Aagaard
2013-01-01
of the noninteracting Kohn-Sham one. When second-order corrections to the density are neglected, the energy expression reduces to a range-separated double-hybrid (RSDH) type of functional, RSDHf, where "f" stands for "full-range integrals" as the regular full-range interaction appears explicitly in the energy...
Energy Technology Data Exchange (ETDEWEB)
Li, Zhong Wei; Min, Chun Gang; Ren, Ai Min; Feng, Ji Kang [Jilin University, Changchun (China); Guo, Jing Fu [Northeast Normal University, Jilin (China); Goddard, John D. [University of Guelph, Ontario (Canada); Zuo, Liang [North China Mineral and Geology Testing Center of CNNC, Tianjin (China)
2010-04-15
In order to find a relationship between firefly luciferases structure and bioluminescence spectra, we focus on excited substrate geometries which may be affected by rigid luciferases. Density functional theory (DFT) and time dependent DFT (TDDFT) were employed. Changes in only six bond lengths of the excited substrate are important in determining the emission spectra. Analysis of these bonds suggests the mechanism whereby luciferases restrict more or less the excited substrate geometries and to produce multicolor bioluminescence.
International Nuclear Information System (INIS)
Boudard, A.
1983-12-01
We have measured the analysing power T 20 in the backward elastic scattering d.p. for 16 energies of the deuteron from 300 MeV to 2300 MeV. This is the region of the observed bump in the backward excitation function of the cross section. This bump is usually thought to be a signature of a Δ(3/2,3/2 + ) dynamically excited in the intermediate state. We have also measured Ay and Ayy from 70 0 to 180 0 for Tsub(d)=1200 MeV. we have compared both T 20 and the backward cross section with a coherent sum between direct neutron exchange and Δ excitation by intermediate exchanges of π and rho mesons. The overall shape of the cross section is reproduced. Unlike the earlier measurements from Argonne, there is a deep minimum in T 20 at Tsub(d)=600 MeV, in agreement with the predictions of direct exchange models. However, an additional structure producing a second minimum at Tsub(d)=1400 MeV (√S=3240 MeV) is never reproduced by our calculations. This suggests either that refinements in the Δ treatment are needed or that a new reaction mechanism (resonance) takes place in that region [fr
Ihalainen, J.A.; Linnanto, J.; Myllyperkiö, P.; van Stokkum, I.H.M.; Ücker, B.; Scheer, H.; Korppi-Tommola, J.E.I.
2001-01-01
Two color transient absorption measurements were performed on a LH2 complex from Rhodospirillum molischianum by using several excitation wavelengths (790, 800, 810, and 830 nm) and probing in the spectral region from 790 to 870 nm at room temperature. The observed energy transfer time of ∼1.0 ps
Mester, Dávid; Nagy, Péter R.; Kállay, Mihály
2018-03-01
A reduced-cost implementation of the second-order algebraic-diagrammatic construction [ADC(2)] method is presented. We introduce approximations by restricting virtual natural orbitals and natural auxiliary functions, which results, on average, in more than an order of magnitude speedup compared to conventional, density-fitting ADC(2) algorithms. The present scheme is the successor of our previous approach [D. Mester, P. R. Nagy, and M. Kállay, J. Chem. Phys. 146, 194102 (2017)], which has been successfully applied to obtain singlet excitation energies with the linear-response second-order coupled-cluster singles and doubles model. Here we report further methodological improvements and the extension of the method to compute singlet and triplet ADC(2) excitation energies and transition moments. The various approximations are carefully benchmarked, and conservative truncation thresholds are selected which guarantee errors much smaller than the intrinsic error of the ADC(2) method. Using the canonical values as reference, we find that the mean absolute error for both singlet and triplet ADC(2) excitation energies is 0.02 eV, while that for oscillator strengths is 0.001 a.u. The rigorous cutoff parameters together with the significantly reduced operation count and storage requirements allow us to obtain accurate ADC(2) excitation energies and transition properties using triple-ζ basis sets for systems of up to one hundred atoms.
International Nuclear Information System (INIS)
Faust, H.; Koester, U.; Kessedjian, G.; Sage, C.; Chebboubi, A.
2013-01-01
We review the statistical model and its application for the process of nuclear fission. The expressions for excitation energy and spin distributions for the individual fission fragments are given. We will finally emphasize the importance of measuring prompt gamma decay to further test the statistical model in nuclear fission with the FIPPS project. (authors)
Low energy excitations in superconducting La1.86Sr0.14CuO4
DEFF Research Database (Denmark)
Mason, T.E.; Aeppli, G.; Hayden, S.M.
1993-01-01
We present magnetic neutron scattering and specific heat data on the high-T(c) superconductor La1.86Sr0.14CuO4. Even when the samples are superconducting and the magnetic response, chi'', is suppressed, there are excitations with energies well below 3.5k(B)T(c). The wave-vector dependence of chi...
Energies of the ground state and first excited 0 sup + state in an exactly solvable pairing model
Dinh Dang, N
2003-01-01
Several approximations are tested by calculating the ground-state energy and the energy of the first excited 0 sup + state using an exactly solvable model with two symmetric levels interacting via a pairing force. They are the BCS approximation (BCS), Lipkin-Nogami (LN) method, random-phase approximation (RPA), quasiparticle RPA (QRPA), the renormalized RPA (RRPA), and renormalized QRPA (RQRPA). It is shown that, in the strong-coupling regime, the QRPA which neglects the scattering term of the model Hamiltonian offers the best fit to the exact solutions. A recipe is proposed using the RRPA and RQRPA in combination with the pairing gap given by the LN method. Applying this recipe, it is shown that the superfluid-normal phase transition is avoided, and a reasonably good description for both of the ground-state energy and the energy of the first excited 0 sup + state is achieved. (orig.)
Girka, Igor O.; Pavlenko, Ivan V.; Thumm, Manfred
2018-05-01
Azimuthal surface waves are electromagnetic eigenwaves of cylindrical plasma-dielectric waveguides which propagate azimuthally nearby the plasma-dielectric interface across an axial external stationary magnetic field. Their eigenfrequency in particular can belong to the electron cyclotron frequency range. Excitation of azimuthal surface waves by rotating relativistic electron flows was studied in detail recently in the case of the zeroth radial mode for which the waves' radial phase change within the layer where the electrons gyrate is small. In this case, just the plasma parameters cause the main influence on the waves' dispersion properties. In the case of the first and higher radial modes, the wave eigenfrequency is higher and the wavelength is shorter than in the case of the zeroth radial mode. This gain being of interest for practical applications can be achieved without any change in the device design. The possibility of effective excitation of the higher order radial modes of azimuthal surface waves is demonstrated here. Getting shorter wavelengths of the excited waves in the case of higher radial modes is shown to be accompanied by decreasing growth rates of the waves. The results obtained here are of interest for developing new sources of electromagnetic radiation, in nano-physics and in medical physics.
Neutron radiative capture by the 241Am nucleus in the energy range 1 keV-20 MeV
International Nuclear Information System (INIS)
Zolotarev, K.I.; Ignatyuk, A.V.; Tolstikov, V.A.; Tertychnyj, G.Ya.
1998-01-01
Production of high actinides leads to many technological problems in the nuclear power. The 241 Am(n,γ) 242 Am reaction is one of the sources of high actinide buildup. So a knowledge of the radiative capture cross-section of 241 Am for neutron energies up to 20 MeV is of considerable important for present day fission reactors and future advanced reactors. The main goal of this paper is the evaluation of the excitation function for the reaction 241 Am(n,γ) 242 Am in the energy range 1 keV-20 MeV. The evaluation was done on the basis of analysed experimental data, data from theoretical model calculations and systematic predictions for 14.5 MeV and 20 MeV. Data from the present evaluation are compared with the cross-section values given in the evaluations carried out earlier. (author)
Effect of neutron irradiation on the density of low-energy excitations in vitreous silica
International Nuclear Information System (INIS)
Smith, T.L.
1979-01-01
Systematic low-temperature measurements of the thermal conductivity, specific heat, dielectric constant, and temperature-dependent ultrasound velocity were made on a single piece of vitreous silica. These measurements were repeated after fast neutron irradiation of the material. It was found that the irradiation produced changes of the same relative magnitude in the low-temperature excess specific heat C/sub ex/, the thermal conductivity kappa, and the anomalous temperature dependence of the ultrasound velocity Δv/v. A corresponding change in the temperature dependent dielectric constant was not observed. It is therefore likely that kappa and Δv/v are determined by the same localized excitations responsible for C/sub ex/, but the temperature dependence of the dielectric constant may have a different, though possibly related, origin. A consistent account for the measured C/sub ex/, kappa, and Δv/v of unirradiated silica is given by the tunneling-state model with a single, energy-dependent density of states. Changes in these three properties due to irradiation can be explained by altering only the density of tunneling states incorporated in the model
Low-energy excitations in impurity substituted CuGeO3
International Nuclear Information System (INIS)
Jones, B. R.; Sushkov, A. B.; Musfeldt, J. L.; Wang, Y. J.; Revcolevschi, A.; Dhalenne, G.
2001-01-01
We report far-infrared reflectance measurements of Zn- and Si-doped CuGeO 3 single crystals as a function of applied magnetic field at low temperature. Overall, the low-energy far-infrared spectra are extraordinarily sensitive to the various phase boundaries in the H-T diagram, with the features being especially rich in the low-temperature dimerized state. Zn impurity substitution rapidly collapses the 44 cm -1 zone-boundary spin Peierls gap, although broadened magnetic excitations are observed at the lightest doping level (0.2%) and a remnant is still observable at 0.7% substitution. In a 0.7% Si-doped sample, there is no evidence of the spin gap. Impurity substitution effects on the intensity of the 98 cm -1 zone-folding mode are striking as well. The lightly doped Zn crystals display an enhanced response, and even at intermediate doping levels, the mode intensity is larger than that in the pristine material. The Si-doped sample also displays an increased intensity of the 98 cm -1 mode in the spin Peierls phase relative to the pure material. The observed trends are discussed in terms of the effect of disorder on the spin gap and 98 cm -1 mode, local oscillator strength sum rules, and broken selection rules
The surrogate-reaction method and excitation-energy sorting in nuclear fission
International Nuclear Information System (INIS)
Jurado, Beatriz
2015-01-01
This manuscript summarises the main activities that I have carried out during the last ten years of research at the Centre d'etudes Nucleaires de Bordeaux-Gradignan (CENBG). It is, to a great extent, a synthesis of nine articles. They can be consulted by the reader that would like to have more detailed information. These articles are denoted as Article I, II.. all along the manuscript. The manuscript is intended to be accessible to PhD students not familiar with the topic. Chapter 1 recalls some of the basic ideas of statistical mechanics and discusses the applicability of its concepts to nuclei. Some of these concepts, in particular the concept of statistical equilibrium, are essential for the topics covered by chapters 2 and 3. Chapter 2 summarises the studies performed by the CENBG collaboration on the surrogate-reaction method in the last ten years. Chapter 3 summarises part of the work done on the modelling of nuclear fission in collaboration with Karl-Heinz Schmidt, it considers the partition of excitation energy and unpaired nucleons in fission on the basis of statistical mechanics. Chapters 2 and 3 contain the bulk of my work, each of them has its own introduction and conclusion sections. Chapter 4 presents the medium and long-term experimental perspectives for the topics described in chapters 2 and 3. (author)
Excitation of short wavelength Alfven oscillations by high energy ions in tokamak
International Nuclear Information System (INIS)
Beasley, C.O. Jr.; Lominadze, J.G.; Mikhailovskii, A.B.
1975-08-01
The excitation of Alfven waves by fast untrapped ions in axisymmetric tokamaks is described by the dispersion relation epsilon 11 - c 2 k/sub parallel bars/ 2 /ω 2 = 0. Using this relation a new class of instability connected with the excitation of Alfven oscillations is described. (U.S.)
Tensor numerical methods in quantum chemistry: from Hartree-Fock to excitation energies.
Khoromskaia, Venera; Khoromskij, Boris N
2015-12-21
We resume the recent successes of the grid-based tensor numerical methods and discuss their prospects in real-space electronic structure calculations. These methods, based on the low-rank representation of the multidimensional functions and integral operators, first appeared as an accurate tensor calculus for the 3D Hartree potential using 1D complexity operations, and have evolved to entirely grid-based tensor-structured 3D Hartree-Fock eigenvalue solver. It benefits from tensor calculation of the core Hamiltonian and two-electron integrals (TEI) in O(n log n) complexity using the rank-structured approximation of basis functions, electron densities and convolution integral operators all represented on 3D n × n × n Cartesian grids. The algorithm for calculating TEI tensor in a form of the Cholesky decomposition is based on multiple factorizations using algebraic 1D "density fitting" scheme, which yield an almost irreducible number of product basis functions involved in the 3D convolution integrals, depending on a threshold ε > 0. The basis functions are not restricted to separable Gaussians, since the analytical integration is substituted by high-precision tensor-structured numerical quadratures. The tensor approaches to post-Hartree-Fock calculations for the MP2 energy correction and for the Bethe-Salpeter excitation energies, based on using low-rank factorizations and the reduced basis method, were recently introduced. Another direction is towards the tensor-based Hartree-Fock numerical scheme for finite lattices, where one of the numerical challenges is the summation of electrostatic potentials of a large number of nuclei. The 3D grid-based tensor method for calculation of a potential sum on a L × L × L lattice manifests the linear in L computational work, O(L), instead of the usual O(L(3) log L) scaling by the Ewald-type approaches.
Energy Technology Data Exchange (ETDEWEB)
Dasch, C.J.
1978-09-01
Single rovibrational states of HCl(v=2), HBr(v=2), DCl(v=2), and CO(v=2) were excited with a pulsed optical parametric oscillator (OPO). Total vibrational relaxation rates near - resonance quenchers were measured at 295/sup 0/K using time resolved infrared fluorescence. These rates are attributed primarily to V - V energy transfer, and they generally conform to a simple energy gap law. A small deviation was found for the CO(v) + DCl(v') relaxation rates. Upper limits for the self relaxation by V - R,T of HCl(v=2) and HBr(v=2) and for the two quantum exchange between HCl and HBr were determined. The HF dimer was detected at 295/sup 0/K and 30 torr HF pressure with an optoacoustic spectrometer using the OPO. Pulsed and chopped, resonant and non-resonant spectrophones are analyzed in detail. From experiments and first order perturbation theory, these V - V exchange rates appear to behave as a first order perturbation in the vibrational coordinates. The rotational dynamics are known to be complicated however, and the coupled rotational - vibrational dynamics were investigated theoreticaly in infinite order by the Dillon and Stephenson and the first Magnus approximations. Large ..delta..J transitions appear to be important, but these calculations differ by orders of magnitude on specific rovibrational transition rates. Integration of the time dependent semiclassical equations by a modified Gordon method and a rotationally distorted wave approximation are discussed as methods which would treat the rotational motion more accurately. 225 references.
International Nuclear Information System (INIS)
Inomoto, Michiaki; Tanabe, Hiroshi; Ono, Yasushi; Kuwahata, Akihiro
2013-01-01
Large-amplitude electromagnetic fluctuations of ion-cyclotron-frequency range are detected in a laboratory experiment inside the diffusion region of a magnetic reconnection with a guide field. The fluctuations have properties similar to kinetic Alfvén waves propagating obliquely to the guide field. Temporary enhancement of the reconnection rate is observed during the occurrence of the fluctuations, suggesting a relationship between the modification in the local magnetic structure given by these fluctuations and the intermittent fast magnetic reconnection
Energy relaxation in IR laser excited Hg1-xCdxTe
International Nuclear Information System (INIS)
Storebo, A K; Brudevoll, T; Olsen, O; Norum, O C; Breivik, M
2009-01-01
IR laser excitation of Hg l-x Cd x Te by low-fluence femtosecond and high fluence microsecond pulses was explored for the technologically important alloy fractions x ∼ 0.2 and x ∼ 0.28. We have used first principles (LAPW) electronic structure calculations and finite element modelling, supported by Monte Carlo simulation for the description of femtosecond pulse carrier relaxation and the transport parameters. Laser wavelengths considered were 6.4 - 10.6 μm for x ∼ 0.2 and 3.8 - 4.8 μm for x ∼ 0.28, with an incident 1 microsecond pulse fluence of 2 J/cm 2 . Many energy transfer mechanisms are invoked due to the long timescales of the microsecond pulses, and a main challenge is therefore to elucidate how these interplay in situations away from thermal equilibrium. Mechanisms studied include one- and two-photon absorption (OPA and TPA) across the band gap, inter-valence band absorption (IVA) between light- and heavy hole bands, electron-hole recombination/impact ionization, band gap renormalisation, intra-band free carrier absorption (FCA), excess carrier temperatures, non-equilibrium phonon generation, and refractive index changes. In the high fluence case, lattice temperatures evolve considerably during the laser pulse in response to the heated carriers. The chosen photon energies lie just above the band gap at the starting lattice temperature of 77 K, and nonlinear effects therefore dominate as the material heats up and the band gap begins to exceed the photon energy. Because of the low photon energy we must rely on Auger recombination, inter-valence band absorption and free carrier absorption to heat the carrier plasma. Although some Hg l-x Cd x Te material parameters are now relatively well known, existing data for many of the processes are inadequate for cases far away from thermal equilibrium. Furthermore, the role of Auger recombination in relation to non-intrinsic recombination has been a matter of debate lately. In this respect, information from
Transcript of the proceedings of the first Albuquerque informal range/energy workshop
International Nuclear Information System (INIS)
Brice, D.K.
1981-04-01
An informal workshop was held to discuss aspects of the calculation of range and energy deposition distributions which are of interest in ion implantation experiments. Topics covered include: problems encountered in using published range and energy deposition tabulations; some limitations in the solutions of range/energy transport equations; the effect of the scattering cross section on straggle; Monte Carlo calculations of ranges and straggling; damage studies in aluminum; simulation of heavy-ion irradiation of gold using MARLOWE; and MARLOWE calculations of range distribution parameters - dependence on input data and calculational model
Torchynska, T.; Khomenkova, L.; Slaoui, A.
2018-04-01
Si-rich SiN x films with different stoichiometry were grown on Si substrate by plasma-enhanced chemical vapor deposition. The Si content was varied by changing the NH3/SiH4 gas flow ratio from 0.45 up to 1.0. Conventional furnace annealing at 1100°C for 30 min was applied to produce the Si quantum dots (QDs) in the SiN x films. Spectroscopic ellipsometry was used to determine the refractive index of the SiN x films that allowed estimating the film's stoichiometry. Fourier transform infrared spectroscopy has been also used to confirm the stoichiometry and microstructure. Photoluminescence (PL) spectra of Si-rich SiN x films are complex. A non-monotonous variation of the different PL peaks versus Si excess contents testifies to the competition of different radiative channels. The analysis of PL spectra, measured at the different excitation light energies and variable temperatures, has revealed that the PL bands with the peaks within the range 2.1-3.0 eV are related to the carrier recombination via radiative native defects in the SiN x host. Simultaneously, the PL bands with the peaks at 1.5-2.0 eV are caused by the exciton recombination in the Si QDs of different sizes. The way to control the SiN x emission is discussed.
International Nuclear Information System (INIS)
Wagatsuma, Kazuaki
2015-01-01
This paper describes several interesting excitation phenomena occurring in a microwave-induced plasma (MIP) excited with Okamoto-cavity, especially when a small amount of oxygen was mixed with nitrogen matrix in the composition of the plasma gas. An ion-to-atom ratio of iron, which was estimated from the intensity ratio of ion to atomic lines having almost the same excitation energy, was reduced by adding oxygen gas to the nitrogen MIP, eventually contributing to an enhancement in the emission intensities of the atomic lines. Furthermore, Boltzmann plots for iron atomic lines were observed in a wide range of the excitation energy from 3.4 to 6.9 eV, indicating that plots of the atomic lines having lower excitation energies (3.4 to 4.8 eV) were well fitted on a straight line while those having more than 5.5 eV deviated upwards from the linear relationship. This overpopulation would result from any other excitation process in addition to the thermal excitation that principally determines the Boltzmann distribution. A Penning-type collision with excited species of nitrogen molecules probably explains this additional excitation mechanism, in which the resulting iron ions recombine with captured electrons, followed by cascade de-excitations between closely-spaced excited levels just below the ionization limit. As a result, these high-lying levels might be more populated than the low-lying levels of iron atom. The ionization of iron would be caused less actively in the nitrogen–oxygen plasma than in a pure nitrogen plasma, because excited species of nitrogen molecule, which can provide the ionization energy in a collision with iron atom, are consumed through collisions with oxygen molecules to cause their dissociation. It was also observed that the overpopulation occurred to a lesser extent when oxygen gas was added to the nitrogen plasma. The reason for this was also attributed to decreased number density of the excited nitrogen species due to collisions with oxygen
Durrant, James R
2013-08-13
This review starts with a brief overview of the technological potential of molecular-based solar cell technologies. It then goes on to focus on the core scientific challenge associated with using molecular light-absorbing materials for solar energy conversion, namely the separation of short-lived, molecular-excited states into sufficiently long-lived, energetic, separated charges capable of generating an external photocurrent. Comparisons are made between different molecular-based solar cell technologies, with particular focus on the function of dye-sensitized photoelectrochemical solar cells as well as parallels with the function of photosynthetic reaction centres. The core theme of this review is that generating charge carriers with sufficient lifetime and a high quantum yield from molecular-excited states comes at a significant energetic cost-such that the energy stored in these charge-separated states is typically substantially less than the energy of the initially generated excited state. The role of this energetic loss in limiting the efficiency of solar energy conversion by such devices is emphasized, and strategies to minimize this energy loss are compared and contrasted.
Komoto, Keenan T; Kowalczyk, Tim
2016-10-06
To support the development and characterization of chromophores with targeted photophysical properties, excited-state electronic structure calculations should rapidly and accurately predict how derivatization of a chromophore will affect its excitation and emission energies. This paper examines whether a time-independent excited-state density functional theory (DFT) approach meets this need through a case study of BODIPY chromophore photophysics. A restricted open-shell Kohn-Sham (ROKS) treatment of the S 1 excited state of BODIPY dyes is contrasted with linear-response time-dependent density functional theory (TDDFT). Vertical excitation energies predicted by the two approaches are remarkably different due to overestimation by TDDFT and underestimation by ROKS relative to experiment. Overall, ROKS with a standard hybrid functional provides the more accurate description of the S 1 excited state of BODIPY dyes, but excitation energies computed by the two methods are strongly correlated. The two approaches also make similar predictions of shifts in the excitation energy upon functionalization of the chromophore. TDDFT and ROKS models of the S 1 potential energy surface are then examined in detail for a representative BODIPY dye through molecular dynamics sampling on both model surfaces. We identify the most significant differences in the sampled surfaces and analyze these differences along selected normal modes. Differences between ROKS and TDDFT descriptions of the S 1 potential energy surface for this BODIPY derivative highlight the continuing need for validation of widely used approximations in excited state DFT through experimental benchmarking and comparison to ab initio reference data.
Frank, Marius S.; Hättig, Christof
2018-04-01
We present a pair natural orbital (PNO)-based implementation of coupled cluster singles and doubles (CCSD) excitation energies that builds upon the previously proposed state-specific PNO approach to the excited state eigenvalue problem. We construct the excited state PNOs for each state separately in a truncated orbital specific virtual basis and use a local density-fitting approximation to achieve an at most quadratic scaling of the computational costs for the PNO construction. The earlier reported excited state PNO construction is generalized such that a smooth convergence of the results for charge transfer states is ensured for general coupled cluster methods. We investigate the accuracy of our implementation by applying it to a large and diverse test set comprising 153 singlet excitations in organic molecules. Already moderate PNO thresholds yield mean absolute errors below 0.01 eV. The performance of the implementation is investigated through the calculations on alkene chains and reveals an at most cubic cost-scaling for the CCSD iterations with the system size.
International Nuclear Information System (INIS)
Morjean, M.; Galin, J.; Goldenbaum, F.; Lienard, E.; Chevallier, M.; Dauvergne, D.; Kirsch, R.; Jacquet, D.; and others.
1997-01-01
The blocking technique was used to infer fission lifetimes as a function of excitation energy for uranium-like nuclei formed in the U+Si reactions at 24 MeV/nucleon. The fission lifetimes are found larger than 10 -19 s for excitation energies up to about 250 MeV. (K.A.)
Stefan, V. Alexander; IAPS-team Team
2017-10-01
The novel study of the laser excitation-suppression of the brain waves is proposed. It is based on the pulsed-operated multi-photon fiber-laser interaction with the brain parvalbumin (PV) neurons. The repetition frequency matches the low frequency brain waves (5-100 Hz); enabling the resonance-scanning of the wide range of the PV neurons (the generators of the brain wave activity). The tunable fiber laser frequencies are in the ultraviolet frequency range, thus enabling the monitoring of the PV neuron-DNA, within the 10s of milliseconds. In medicine, the method can be used as an ``instantaneous-on-off anesthetic.'' Supported by Nikola Tesla Labs, Stefan University.
Instrumental aspects of tube-excited energy-dispersive X-ray fluorescence analysis
International Nuclear Information System (INIS)
Adams, F.; Nullens, H.; Espen, P. van
1983-01-01
Energy-dispersive X-ray fluorescence spectrometry is an attractive and widely used method for sensitive multi-element analysis. The method suffers from the extreme density of spectral components in a rather limited energy range which implies the need for computer based spectrum analysis. The method of iterative least squares analysis is the most powerful tool for this. It requires a systematic and accurate description of the spectral features. Other important necessities for accurate analysis are the calibration of the spectrometer and the correction for matrix absorption effects in the sample; they can be calculated from available physical constants. Ours and similar procedures prove that semi-automatic analyses are possible with an accuracy of the order of 5%. (author)
Assessment of tidal range energy resources based on flux conservation in Jiantiao Bay, China
Du, Min; Wu, He; Yu, Huaming; Lv, Ting; Li, Jiangyu; Yu, Yujun
2017-12-01
La Rance Tidal Range Power Station in France and Jiangxia Tidal Range Power Station in China have been both long-term successful commercialized operations as kind of role models for public at large for more than 40 years. The Sihwa Lake Tidal Range Power Station in South Korea has also developed to be the largest marine renewable power station with its installed capacity 254 MW since 2010. These practical applications prove that the tidal range energy as one kind of marine renewable energy exploitation and utilization technology is becoming more and more mature and it is used more and more widely. However, the assessment of the tidal range energy resources is not well developed nowadays. This paper summarizes the main problems in tidal range power resource assessment, gives a brief introduction to tidal potential energy theory, and then we present an analyzed and estimated method based on the tide numerical modeling. The technical characteristics and applicability of these two approaches are compared with each other. Furthermore, based on the theory of tidal range energy generation combined with flux conservation, this paper proposes a new assessment method that include a series of evaluation parameters and it can be easily operated to calculate the tidal range energy of the sea. Finally, this method is applied on assessment of the tidal range power energy of the Jiantiao Harbor in Zhejiang Province, China for demonstration and examination.
Cross sections for energy transfer in collisions between two excited sodium atoms
International Nuclear Information System (INIS)
Huennekens, J.; Gallagher, A.
1983-01-01
We have measured cross sections, sigma/sub n/L, for the excitation transfer process Na(3P)+Na(3P)→Na(3S)+Na(nL), where nL is the 4D or 5S level. Our results are sigma/sub 4D/ = 23 A 2 +- 35% and sigma/sub 5S/ = 16 A 2 +- 35% at Tapprox.600 K. To obtain these cross sections we have used pulsed excitation and measured the intensities of 4D, 5S, and 3P fluorescence emissions, and the spatial distribution of excited atoms resulting from radiation diffusion, as well as the excited atom density as a function of time. Additionally, we have accounted for (time-dependent) radiation trapping of 3P and nL level radiation and for the resulting anisotropies of these fluorescence emissions. Comparisons of our results with theory have been made, and their relevance to other experiments is discussed
Energy of nuclear-active particles in the 1-50 TeV energy range
International Nuclear Information System (INIS)
Kotlyarevskij, D.M.; Garsevanishvili, L.P.; Morozov, I.V.
1979-01-01
The ''TsKhRA-TsKARO'' installation designed for the investigation of cosmic beams interaction with nuclei in the energy range of 1-50 TeV is described. The installation comprises a magnetic spark spectrometer, photography system, ionization calorimeter and scintillating trigger device. The ionization calorimeter contains 12 rows of ionization chambers interlayed with 4 lead and 8 iron absorbers. The rows of ionization chambers of the calorimeter upper half are placed in the mutually-perpendicular direction to restore the direction and spatial situation of the electron-nuclear cascade. All in all the ionization calorimeter contains 100 channels of preintensifiers from which the information is transmitted to the terminal intensifiers and then to the storage cells. The aperture ratio of the whole installation (taking account of the upper chambers) is 0.5 m 2 /steradian, and the aperture ratio of the calorimeter together with the lower chambers is approximately 2 m 2 /steradian. Presented are integral spectra of the hadrons at the height of mountains and at the height of 2500 m above sea level obtained with the help of the installation described. Comparison of the number of charged and neutral particles recorded with the ''TsKhRA-TsKARO'' installation agrees well with the known ratio of charged and neutral cosmic hadrons on the heights of mountains n/c = 0.52+-0.05
Sun, Jin; Li, Guang; Liang, WanZhen
2015-07-14
A real-time time-dependent density functional theory coupled with the classical electrodynamics finite difference time domain technique is employed to systematically investigate the optical properties of hybrid systems composed of silver nanoparticles (NPs) and organic adsorbates. The results demonstrate that the molecular absorption spectra throughout the whole energy range can be enhanced by the surface plasmon resonance of Ag NPs; however, the absorption enhancement ratio (AER) for each absorption band differs significantly from the others, leading to the quite different spectral profiles of the hybrid complexes in contrast to those of isolated molecules or sole NPs. Detailed investigations reveal that the AER is sensitive to the energy gap between the molecular excitation and plasmon modes. As anticipated, two separate absorption bands, corresponding to the isolated molecules and sole NPs, have been observed at a large energy gap. When the energy gap approaches zero, the molecular excitation strongly couples with the plasmon mode to form the hybrid exciton band, which possesses the significantly enhanced absorption intensity, a red-shifted peak position, a surprising strongly asymmetric shape of the absorption band, and the nonlinear Fano effect. Furthermore, the dependence of surface localized fields and the scattering response functions (SRFs) on the geometrical parameters of NPs, the NP-molecule separation distance, and the external-field polarizations has also been depicted.
International Nuclear Information System (INIS)
Montero-Alejo, Ana L.; Gonzalez-Santana, Susana; Montero-Cabrera, Luis A.; Hernandez-Rodriguez, Erix Wiliam; Fuentes-Montero, Maria Elena; Bunge-Molina, Carlos F.; Gonzalez, Augusto
2008-01-01
Theoretical prediction of vertical excitation energies and an estimation of charge distributions of polyatomic systems can be calculated, through the configuration interaction of single (CIS) excited determinants procedure, with the CNDOL (Complete Neglect of Differential Overlap considering the l azimuthal quantum number) Hamiltonians. This method does not use adjusted parameters to fit experimental data and only employ a priori data on atomic orbitals and simple formulas to substitute large computations of electronic integrals. In this sense, different functions for bi-electron integrals have been evaluated in order to improve the approximate Hamiltonian. The reliability of predictions and theoretical consistence has been tested with a benchmark set of organic molecules that covers important classes of chromophores including polyenes and other unsaturated aliphatic compounds, aromatic, hydrocarbons, heterocycles, carbonyl compounds, and nucleobases. The calculations are done at identical geometries (MP2) with the same basis set (6-31G) for these medium-sized molecules and the obtained results were statistically compared with other analogous methods and experimental data. The accuracy of prediction of each CNDOL vertical transitions energy increases while the active space is more complete allowing the best variational optimization of CIS matrices i.e. molecular excited states. Moreover and due to the feasible computation procedure for large polyatomic systems, the studies have been extended, as a preliminary work, in the field of optoelectronic materials for photovoltaic applications. Hence, the excitation energies of different conjugated Phenyl-cored Thiophene Dendrimers optimized by DFT (Density Functional Theory) were calculated and show good agreement with the experiment data. The predicted charge distribution during the excitation contributes to understand the photophysics process on these kind materials. (Full text)
Jennings, Robert C; Zucchelli, Giuseppe
2014-01-01
We examine ergodicity and configurational entropy for a dilute pigment solution and for a suspension of plant photosystem particles in which both ground and excited state pigments are present. It is concluded that the pigment solution, due to the extreme brevity of the excited state lifetime, is non-ergodic and the configurational entropy approaches zero. Conversely, due to the rapid energy transfer among pigments, each photosystem is ergodic and the configurational entropy is positive. This decreases the free energy of the single photosystem pigment array by a small amount. On the other hand, the suspension of photosystems is non-ergodic and the configurational entropy approaches zero. The overall configurational entropy which, in principle, includes contributions from both the single excited photosystems and the suspension which contains excited photosystems, also approaches zero. Thus the configurational entropy upon photon absorption by either a pigment solution or a suspension of photosystem particles is approximately zero. Copyright © 2014 Elsevier B.V. All rights reserved.
New even parity energy levels of Pr I found by excitation of transitions in the region 560 - 695 nm
Energy Technology Data Exchange (ETDEWEB)
Syed, Tanweer Iqbal; Khan, Shamim; Imran, Siddiqui; Zaheer, Uddin; Windholz, Laurentius [Inst. f. Experimentalphysik, Techn. Univ. Graz, Petersgasse 16, A-8010 Graz (Austria)
2011-07-01
The knowledge of electronic levels is essentially needed for a description of the interactions between the electrons of an atom and for the classification of an atomic spectrum. We have studied the hyperfine structure of Praseodymium spectral lines in the region from 560 to 695 nm. The hyperfine structure of a large number of unclassified Pr I-lines have been investigated by using the method of laser induced fluorescence in a hollow cathode discharge. During this investigation, we have discovered twelve energy levels with even parity, which were previously unknown. The excitation source was a ring dye laser operated with R6G, Kiton red, or DCM. J-quantum numbers and magnetic dipole interaction constants A for upper and lower levels have been determined from the recorded hyperfine structures. The energies of new levels have been determined by using these constants, excitation and fluorescence wavelengths. Promising excitation wavelengths have been taken from Fourier transform spectra. The new levels were confirmed by at least one second laser excitation.
International Nuclear Information System (INIS)
Moenke, D.; Bengtsson, P.; Engstroem, L.; Hutton, R.; Jupen, C.; Kirm, M.; Westerlind, M.
1994-01-01
We have investigated the relative excitation functions for low-lying singly excited and low-lying core-excited levels in S V (S 4+ ) to S IX (S 8+ ) after beam-foil excitation using ions in the energy range 2--10 MeV. The spectral line intensities have been normalized to the same number of particles at each ion energy and corrections for the level lifetimes have been made. The overall accuracy of the measured relative excitation function at each energy and charge state is estimated to be better than 2%. A comparison of the relative excitation functions for singly excited and core-excited lines shows a difference in S VII, but not in S VI
International Nuclear Information System (INIS)
Pouliot, J.; Dore, D.; Houde, S.; Laforest, R.; Roy, R.; St-Pierre, C.; Chan, Y.; Horn, D.; Horn, D.
1991-01-01
A comparison of the multiple breakup of 16 O projectiles scattered by a Au target at three different energies (32.5, 50 and 70 MeV/N) is presented. The excitation energy spectra of the primary projectile-like nuclei decaying into specific output channels were reconstructed. The excitation energy of the target is found to increase faster with beam energy than the one for the quasi-projectile
Energy loss of muons in the energy range 1-10000 GeV
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Lohmann, W.; Kopp, R.; Voss, R.
1985-01-01
A summary is given of the most recent formulae for the cross-sections contributing to the energy loss of muons in matter, notably due to electro-magnetic interactions (ionization, bremsstrahlung and electron-pair production) and nuclear interactions. Computed energy losses dE/dx are tabulated for muons with energy between 1 GeV and 10,000 GeV in a number of materials commonly used in high-energy physics experiments. In comparison with earlier tables, these show deviations that grow with energy and amount to several per cent at 200 GeV muon energy. (orig.)
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Charity, R.J.; Sobotka, L.G.
2005-01-01
In the independent-particle model, the nuclear level density is determined from the neutron and proton single-particle level densities. The single-particle level density for the positive-energy continuum levels is important at high excitation energies for stable nuclei and at all excitation energies for nuclei near the drip lines. This single-particle level density is subdivided into compound-nucleus and gas components. Two methods are considered for this subdivision: In the subtraction method, the single-particle level density is determined from the scattering phase shifts. In the Gamov method, only the narrow Gamov states or resonances are included. The level densities calculated with these two methods are similar; both can be approximated by the backshifted Fermi-gas expression with level-density parameters that are dependent on A, but with very little dependence on the neutron or proton richness of the nucleus. However, a small decrease in the level-density parameter is predicted for some nuclei very close to the drip lines. The largest difference between the calculations using the two methods is the deformation dependence of the level density. The Gamov method predicts a very strong peaking of the level density at sphericity for high excitation energies. This leads to a suppression of deformed configurations and, consequently, the fission rate predicted by the statistical model is reduced in the Gamov method
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Vinodkumar, Minaxi; Bhutadia, Harshad; Antony, Bobby; Mason, Nigel
2011-01-01
This paper reports computational results of the total cross sections for electron impact on H 2 CO and HCOOH over a wide range of electron impact energies from 0.01 eV to 2 keV. The total cross section is presented as sum of the elastic and electronic excitation cross sections for incident energies. The calculation uses two different methodologies, below the ionization threshold of the target the cross section is calculated using the UK molecular R-matrix code through the Quantemol-N software package while cross sections at higher energies are evaluated using the spherical complex optical potential formalism. The two methods are found to be consistent at the transition energy (∼15 eV). The present results are, in general, found to be in good agreement with previous experimental and theoretical results (wherever available) and, thus, the present results can serve as a benchmark for the cross section over a wide range of energy.
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Hemanadhan, M; Shamim, Md; Harbola, Manoj K
2014-01-01
The modified local spin density (MLSD) functional and the related local potential for excited states is tested by employing the ionization potential theorem. The exchange functional for an excited state is constructed by splitting k-space. Since its functional derivative cannot be obtained easily, the corresponding exchange potential is given by an analogy to its ground-state counterpart. Further, to calculate the highest occupied orbital energy ϵ max accurately, the potential is corrected for its asymptotic behaviour by employing the van Leeuwen and Baerends (LB) correction to it. ϵ max so obtained is then compared with the ΔSCF ionization energy calculated using the MLSD functional with self-interaction correction for the orbitals involved in the transition. It is shown that the two match quite accurately. The match becomes even better by tuning the LB correction with respect to a parameter in it. (paper)
Lowest excited-state impurity binding energy in InGaN/GaN parabolic QWW: magnetic field effect
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Haddou El Ghazi; Anouar Jorio; Izeddine Zorkani
2013-01-01
In this paper, we have investigated the magnetic field effect on the lowest excited-state binding energy of hydrogenic shallow-donor impurity in wurtzite (In,Ga)N/GaN parabolic transversal-section quantum-well wire (PQWW) using the finite-difference method within the quasi-one-dimensional effective potential model. The calculations are performed within the framework of the effective mass approximation. A cylindrical QWW effective radius is taken into account to describe the lateral confinement strength. The numerical results show that: (i) the probability density is the largest on a circularity whose radius is the effective radius and (ii) the lowest excited-state binding energy is the largest when an impurity is located on this circularity while it starts to decrease as the impurity is away from the circularity. (author)
Excitation of the 4.3-μm bands of CO2 by low-energy electrons
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Bulos, R.R.; Phelps, A.V.
1976-01-01
Rate coefficients for the excitation of the 4.3-μm bands of CO 2 by low-energy electrons in CO 2 have been measured using a drift-tube technique. The CO 2 density [(1.5 to 7) x 10 17 molecules/cm 3 ] was chosen to maximize the radiation reaching the detector. Line-by-line transmission calculations were used to take into account the absorption of 4.3-μm radiation. A small fraction of the approximately 10 -8 W of the 4.3-μm radiation produced by the approximately 10 -7 -A electron current was incident on an InSb photovoltaic detector. The detector calibration and absorption calculations were checked by measuring the readily calculated excitation coefficients for vibrational excitation of N 2 containing a small concentration of CO 2 . For pure CO 2 the number of molecules capable of emitting 4.3-μm radiation produced per cm of electron drift and per CO 2 molecule varied from 10 -17 cm -2 at E/N = 6 x 10 -17 V cm 2 to 5.4 x 10 -16 cm -2 at E/N = 4 x 10 -16 V cm 2 . Here E is the electric field and N is total gas density. The excitation coefficients at lower E/N are much larger than estimated previously. A set of vibrational excitation cross sections is obtained for CO 2 which is consistent with the excitation coefficient data and with most of the published electron-beam data
Taner UÇAR; Onur MERTER
2018-01-01
In energy-based seismic design approach, earthquake ground motion is considered as an energy input to structures. The earthquake input energy is the total of energy components such as kinetic energy, damping energy, elastic strain energy and hysteretic energy, which contributes the most to structural damage. In literature, there are many empirical formulas based on the hysteretic model, damping ratio and ductility in order to estimate hysteretic energy, whereas they do not directly consider t...
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Gareev, F.A.; Zhidkova, I.E.; Ratis, Yu.L.
2004-01-01
We have concluded that cold transmutation of nuclei is possible in the framework of the modern physical theory - excitation and ionization of atoms and the universal resonance synchronization principle are responsible for it. Investigation of this phenomenon requires knowledge of different branches of science: nuclear and atomic physics, chemistry and electrochemistry, condensed matter and solid state physics. The results of this research field can provide a new source of energy, substances and technologies. (author)
Belyaeva, N E; Schmitt, F-J; Paschenko, V Z; Riznichenko, G Yu; Rubin, A B; Renger, G
2011-02-01
Our recently presented PS II model (Belyaeva et al., 2008) was improved in order to permit a consistent simulation of Single Flash Induced Transient Fluorescence Yield (SFITFY) traces that were earlier measured by Steffen et al. (2005) on whole leaves of Arabidopsis (A.) thaliana at four different energies of the actinic flash. As the essential modification, the shape of the actinic flash was explicitly taken into account assuming that an exponentially decaying rate simulates the time dependent excitation of PS II by the 10 ns actinic flash. The maximum amplitude of this excitation exceeds that of the measuring light by 9 orders of magnitude. A very good fit of the SFITFY data was achieved in the time domain from 100 ns to 10s for all actinic flash energies (the maximum energy of 7.5 × 10¹⁶ photons/(cm²flash) is set to 100%, the relative energies of weaker actinic flashes were of ∼8%, 4%, ∼1%). Our model allows the calculation and visualization of the transient PS II redox state populations ranging from the dark adapted state, via excitation energy and electron transfer steps induced by pulse excitation, followed by final relaxation into the stationary state eventually attained under the measuring light. It turned out that the rate constants of electron transfer steps are invariant to intensity of the actinic laser flash. In marked contrast, an increase of the actinic flash energy by more than two orders of magnitude from 5.4×10¹⁴ photons/(cm²flash) to 7.5×10¹⁶ photons/(cm²flash), leads to an increase of the extent of fluorescence quenching due to carotenoid triplet (³Car) formation by a factor of 14 and of the recombination reaction between reduced primary pheophytin (Phe(-)) and P680(+) by a factor of 3 while the heat dissipation in the antenna complex remains virtually constant. The modified PS II model offers new opportunities to compare electron transfer and dissipative parameters for different species (e.g. for the green algae and the
Numerical simulation on range of high-energy electron moving in accelerator target
International Nuclear Information System (INIS)
Shao Wencheng; Sun Punan; Dai Wenjiang
2008-01-01
In order to determine the range of high-energy electron moving in accelerator target, the range of electron with the energy range of 1 to 100 MeV moving in common target material of accelerator was calculated by Monte-Carlo method. Comparison between the calculated result and the published data were performed. The results of Monte-Carlo calculation are in good agreement with the published data. Empirical formulas were obtained for the range of high-energy electron with the energy range of 1 to 100 MeV in common target material by curve fitting, offering a series of referenced data for the design of targets in electron accelerator. (authors)
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Aggarwal, Kanti M; Keenan, Francis P
2013-01-01
We report calculations of energy levels, radiative rates and electron impact excitation cross sections and rates for transitions in He-like Ga XXX, Ge XXXI, As XXXII, Se XXXIII and Br XXXIV. The grasp (general-purpose relativistic atomic structure package) is adopted for calculating energy levels and radiative rates. For determining the collision strengths, and subsequently the excitation rates, the Dirac atomic R-matrix code (darc) is used. Oscillator strengths, radiative rates and line strengths are reported for all E1, E2, M1 and M2 transitions among the lowest 49 levels of each ion. Additionally, theoretical lifetimes are provided for all 49 levels of the above five ions. Collision strengths are averaged over a Maxwellian velocity distribution and the effective collision strengths obtained listed over a wide temperature range up to 10 8 K. Comparisons are made with similar data obtained using the flexible atomic code (fac) to highlight the importance of resonances, included in calculations with darc, in the determination of effective collision strengths. Discrepancies between the collision strengths from darc and fac, particularly for some forbidden transitions, are also discussed. Finally, discrepancies between the present results for effective collision strengths with the darc code and earlier semi-relativistic R-matrix data are noted over a wide range of electron temperatures for many transitions in all ions. (paper)
Aggarwal, Kanti M.; Keenan, Francis P.
2013-04-01
We report calculations of energy levels, radiative rates and electron impact excitation cross sections and rates for transitions in He-like Ga XXX, Ge XXXI, As XXXII, Se XXXIII and Br XXXIV. The grasp (general-purpose relativistic atomic structure package) is adopted for calculating energy levels and radiative rates. For determining the collision strengths, and subsequently the excitation rates, the Dirac atomic R-matrix code (darc) is used. Oscillator strengths, radiative rates and line strengths are reported for all E1, E2, M1 and M2 transitions among the lowest 49 levels of each ion. Additionally, theoretical lifetimes are provided for all 49 levels of the above five ions. Collision strengths are averaged over a Maxwellian velocity distribution and the effective collision strengths obtained listed over a wide temperature range up to 108 K. Comparisons are made with similar data obtained using the flexible atomic code (fac) to highlight the importance of resonances, included in calculations with darc, in the determination of effective collision strengths. Discrepancies between the collision strengths from darc and fac, particularly for some forbidden transitions, are also discussed. Finally, discrepancies between the present results for effective collision strengths with the darc code and earlier semi-relativistic R-matrix data are noted over a wide range of electron temperatures for many transitions in all ions.
International Nuclear Information System (INIS)
Rurarz, E.
1994-01-01
This report describes investigations of the excitation functions of the proton induced reactions on 14 targets (Mn, Co, Br, Rb, 99 Tc, 113 Cd, 114 Cd, Cd, I, Cs, Ta, 206,207,208 Pb) leading directly or indirectly to the formation of radionuclides 52 Fe, 77 Br, 82 Rb, 97 Ru, 111 In, 123 I, 127 Xe, 128 Cs, 178 Ta and 201 Tl frequently used in diagnostic procedures of nuclear medicine. The measurements of the excitation functions were made over a wide proton energy range from the reaction threshold up to 100 MeV using the stacked foil (or pellet) technique. Small energy steps were used to allow for accurate determination of the structure of excitation functions. For 97 Ru, 111 In and 127 Xe formation with protons, new reaction channels and targets were used and data concerning this method are published for the first time. The data for 52 Fe, 77 Br, 82 Rb, 123 I, 128 Cs and 201 Tl obtained in the present work for the E p =70-100 MeV region are also published for the first time. The measured excitation functions for the formation of desired (and undesired) radionuclides (altogether 28 excitation functions) are compared with the theoretical ones calculated on the basis of a hybrid model of nuclear reactions in the form of the Overlaid Alice computer code. In order to determine the contribution of the competitive reaction channels to the purity of the produced, desired radionuclide, the excitation functions of the accompanying reactions were also calculated. The 122 calculated excitation functions for the possible contaminant are given in the present work. The comparison of experimental excitation functions with the results of model calculations showed satisfactory agreement, especially if one considers, that no parameter adjustment for individual reaction products was undertaken. From the measured excitation functions the production yields for 28 radionuclides mentioned above have been determined (author). 262 refs, 65 figs, 34 tabs
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Ricz, S.; Holste, K.; Borovik, Jr.A.A.; Bernhardt, D.; Schippers, S.; Muller, A.; Kover, A.; Varga, D.
2011-01-01
Complete text of publication follows. A left-right asymmetry was observed experimentally for the outer s-shell photoelectrons of noble gases and of the H 2 molecule in our previous studies (see the cited articles for the definition of 'left' and 'right' as well as for the details of the experimental method). Recently, the angular distribution of 4p photoelectrons of Kr was measured with linearly polarized synchrotron radiation in the photon energy range (90 - 94.4 eV) of the 3d -1 → np resonant excitations in order to determine the anisotropy parameters. Now, also the left-right asymmetry parameters have been determined from the measured spectra of Ref. [3]. The experiment was performed at beamline BW3 of the DORIS III storage ring at HASYLAB (Hamburg, Germany). The emitted electrons were analyzed using the ESA-22D electrostatic electron spectrometer. Fig. 1 shows the measured left-right asymmetry parameters (A LR ) of the two fine structure components of Kr 4p photoelectrons. The asymmetry parameters (A LR ) are increasing with increasing photon energies reaching a maximum value of 0.04, definitely different from zero when considering the error bars. Furthermore, the left-right asymmetry parameters oscillate around the (3d 3/2,5/2 ) -1 → 5p resonant excitation for both fine structure components. Currently, we do not know what kind of interaction can produce a left-right asymmetry in photon-atom collisions but the shape of the oscillations shows interference between the unknown and the resonant excitation channels. One of the most important observations is that the sign of A LR changes from positive to negative and then back again to positive just within a narrow photon energy range of only 250 meV around the (3d 5/2 ) -1 → 5p resonant excitation. Within such a narrow range artificial asymmetry of the experimental setup is totally unconceivable. Acknowledgements. The authors thank the DORIS III staff for providing excellent working conditions. This work was
The study of quasi-projectiles produced in Ni+Ni and Ni+Au collisions: excitation energy and spin
International Nuclear Information System (INIS)
Buta, A.
2003-02-01
During the collision between the projectile and the target nuclei in the intermediate energy regime (E < 100 MeV/nucleon) two excited nuclei are mainly observed in the exit channel, the quasi projectile (QP) and the quasi target. They disintegrate by particle emission. However, this binary picture is perturbed by the emission of particles and light fragments with velocities intermediate between the projectile velocity and the target one, all along the interaction (midrapidity component). This work aim to determine the excitation energy and the intrinsic angular momentum (or spin) of quasi-projectiles produced in the Ni+Ni and Ni+Au collisions at 52 and 90 MeV/nucleon. The excitation energy is deduced from the kinematical characteristics of particles emitted by the quasi-projectile. They have to be separated from midrapidity particles. Three different scenarios have been used for this purpose. The spin of the quasi-projectile has been extracted from the experimental data by mean of proton and alpha particles multiplicities emitted by the QP in the Ni+Au at 52 MeV/nucleon reaction. The results have been compared to the predictions of a theoretical model based on nucleon transfers. Their evolution is qualitatively reproduced as a function of the violence of the collision. (author)
International Nuclear Information System (INIS)
Wundt, Benedikt J.; Jentschura, Ulrich D.
2008-01-01
Canonically, the quantum electrodynamic radiative corrections in bound systems have been evaluated in photon energy regularization, i.e., using a noncovariant overlapping parameter that separates the high-energy relativistic scales of the virtual quanta from the nonrelativistic domain. Here, we calculate the higher-order corrections to the one-photon self-energy calculation with three different overlapping parameters (photon energy, photon mass and dimensional regularization) and demonstrate the reparameterization invariance of nonrelativistic quantum electrodynamics (NRQED) using this particular example. We also present new techniques for the calculation of the low-energy part of this correction, which lead to results for the Lamb shift of highly excited states that are important for high-precision spectroscopy
Energy Technology Data Exchange (ETDEWEB)
Wundt, Benedikt J. [Max-Planck-Institut fuer Kernphysik, Postfach 103980, 69029 Heidelberg (Germany); Jentschura, Ulrich D. [Max-Planck-Institut fuer Kernphysik, Postfach 103980, 69029 Heidelberg (Germany); Institut fuer Theoretische Physik, Philosophenweg 16, 69120 Heidelberg (Germany)], E-mail: ulrich.jentschura@mpi-hd.mpg.de
2008-01-24
Canonically, the quantum electrodynamic radiative corrections in bound systems have been evaluated in photon energy regularization, i.e., using a noncovariant overlapping parameter that separates the high-energy relativistic scales of the virtual quanta from the nonrelativistic domain. Here, we calculate the higher-order corrections to the one-photon self-energy calculation with three different overlapping parameters (photon energy, photon mass and dimensional regularization) and demonstrate the reparameterization invariance of nonrelativistic quantum electrodynamics (NRQED) using this particular example. We also present new techniques for the calculation of the low-energy part of this correction, which lead to results for the Lamb shift of highly excited states that are important for high-precision spectroscopy.
Low-energy scattering of excited helium atoms by rare gases
International Nuclear Information System (INIS)
Peach, G.
1978-01-01
The construction of semi-empirical model potentials for systems composed of helium in an excited state (Hestar) and a rare-gas atom (He or Ne) is described. The model of the atom-atom pair which has been adopted is one in which the excited electron is included explicitly, but the residual He + ion and the rare-gas atom are treated simply as cores which may be polarised. The results obtained are in satisfactory agreement with other calculations where they are available. (author)
International Nuclear Information System (INIS)
Steckmeyer, J.C.; Genouin-Duhamel, E.; Vient, E.; Colin, J.; Durand, D.; Auger, G.; Bacri, C.O.; Bellaize, N.; Borderie, B.; Bougault, R.; Bouriquet, B.; Brou, R.; Buchet, P.; Charvet, J.L.; Chbihi, A.; Cussol, D.; Dayras, R.; De Cesare, N.; Demeyer, A.; Dore, D.; Frankland, J.D.; Galichet, E.; Gerlic, E.; Guinet, D.; Hudan, S.; Lautesse, P.; Lavaud, F.; Laville, J.L.; Lecolley, J.F.; Leduc, C.; Legrain, R.; Le Neindre, N.; Lopez, O.; Louvel, M.; Maskay, A.M.; Nalpas, L.; Normand, J.; Parlog, M.; Pawlowski, P.; Plagnol, E.; Rivet, M.F.; Rosato, E.; Saint-Laurent, F.; Tabacaru, G.; Tamain, B.; Tassan-Got, L.; Tirel, O.; Turzo, K.; Vigilante, M.; Volant, C.; Wieleczko, J.P.
2001-01-01
The excitation energy and angular momentum transferred to quasiprojectiles have been measured in the 129 Xe+ nat Sn collisions at bombarding energies between 25 and 50 MeV/nucleon. The excitation energy of quasiprojectiles has been determined from the kinetic energy of all decay products (calorimetry). It increases with the violence of the collision, approaching 10 MeV/nucleon in the most dissipative ones. The angular momentum has been deduced from the kinetic energies and angular distributions of the emitted light charged particles (p, d, t, 3 He and α). The (apparent) spin value decreases with the violence of the collision. Larger spin values are observed at the lowest bombarding energy. Data are compared with the predictions of dynamical and statistical models. They reproduce the data in a quantitative way indicating that large spin values are transferred to quasiprojectiles during the interaction. The results show that the one-body dissipation formalism still applies at intermediate bombarding energies and low-energy dissipations. With the increase of the energy, the data seem to be better described when the two-body interaction is accounted for
International Nuclear Information System (INIS)
Runge, Serge.
1980-12-01
The relative cross-sections of ionizing collisions between He + He and He + Ne atoms, have been studied, the helium being excited in a state (3 1 p) by a laser beam. The results obtained made it possible (a) to reveal in a direct manner the production of molecular ions He 2 + and He Ne + and (b) to determine the relative change in the associative ionizing cross-section in the area (0.035 - 0.17 eV) in the He (3 1 P) + Ne collision, despite the very short life of the He (3 1 P) excited state (1.7 ns). The production of He 2 + ions from an He (3 1 P) + He collision sets an upper limit to the appearance potential of these ions. The experimental study of the associative ionization in the He (3 1 P) + Ne system made it possible to extend the utilization of the GAMMA(R) self ionization model, already tested for the metastable states, to the radiative states. The GAMMA(R) model seems well suited for the description of collisions of the A excited + B type, where the excitation energy of A is greater than the ionization potential of B [fr
Freundorfer, Katrin; Kats, Daniel; Korona, Tatiana; Schütz, Martin
2010-12-28
A new multistate local CC2 response method for calculating excitation energies and first-order properties of excited triplet states in extended molecular systems is presented. The Laplace transform technique is employed to partition the left/right local CC2 eigenvalue problems as well as the linear equations determining the Lagrange multipliers needed for the properties. The doubles part in the equations can then be inverted on-the-fly and only effective equations for the singles part must be solved iteratively. The local approximation presented here is adaptive and state-specific. The density-fitting method is utilized to approximate the electron-repulsion integrals. The accuracy of the new method is tested by comparison to canonical reference values for a set of 12 test molecules and 62 excited triplet states. As an illustrative application example, the lowest four triplet states of 3-(5-(5-(4-(bis(4-(hexyloxy)phenyl)amino)phenyl)thiophene-2-yl)thiophene-2-yl)-2-cyanoacrylic acid, an organic sensitizer for solar-cell applications, are computed in the present work. No triplet charge-transfer states are detected among these states. This situation contrasts with the singlet states of this molecule, where the lowest singlet state has been recently found to correspond to an excited state with a pronounced charge-transfer character having a large transition strength.
POSITRON-ELECTRON DECAY OF SI-28, AT AN EXCITATION-ENERGY OF 50-MEV
BUDA, A; BACELAR, JC; BALANDA, A; VANDERPLOEG, H; SUJKOWSKI, Z; VANDERWOUDE, A
1993-01-01
The electron-positron pair decay of Si-28 at 50 MeV excitation produced by the isospin T=0 (alpha + Mg-24) and the mixed isospin T=0,1 (He-3 + Mg-25) reactions has been studied using a special designed Positron-Electron pair spectrometer PEPSI.
Positron-electron decay of 28Si at an excitation energy of 50 MeV
International Nuclear Information System (INIS)
Buda, A.; Bacelar, J.C.; Balanda, A.; Ploeg, H. van der; Sujkowski, Z.; Woude, A. van der
1993-01-01
The electron-positron pair decay of 28 Si at 50 MeV excitation produced by the isospin T=0 (α+ 24 Mg) and the mixed isospin T=0, 1 ( 3 He+ 25 Mg) reactions has been studied using a special designed Positron-Electron pair spectrometer PEPSI. (orig.)
Oxygen auroral transition laser system excited by collisional and photolytic energy transfer
International Nuclear Information System (INIS)
Murray, J.R.; Powell, H.T.; Rhodes, C.K.
1975-06-01
The properties of laser media involving the auroral transition of atomic oxygen and analogous systems are examined. A discussion of the atomic properties, collisional mechanisms, excitation processes, and collisionally induced radiative phenomena is given. Crossing phenomena play a particularly important role in governing the dynamics of the medium
Radgolchin, Moeen; Moeenfard, Hamid
2018-02-01
The construction of self-powered micro-electro-mechanical units by converting the mechanical energy of the systems into electrical power has attracted much attention in recent years. While power harvesting from deterministic external excitations is state of the art, it has been much more difficult to derive mathematical models for scavenging electrical energy from ambient random vibrations, due to the stochastic nature of the excitations. The current research concerns analytical modeling of micro-bridge energy harvesters based on random vibration theory. Since classical elasticity fails to accurately predict the mechanical behavior of micro-structures, strain gradient theory is employed as a powerful tool to increase the accuracy of the random vibration modeling of the micro-harvester. Equations of motion of the system in the time domain are derived using the Lagrange approach. These are then utilized to determine the frequency and impulse responses of the structure. Assuming the energy harvester to be subjected to a combination of broadband and limited-band random support motion and transverse loading, closed-form expressions for mean, mean square, correlation and spectral density of the output power are derived. The suggested formulation is further exploited to investigate the effect of the different design parameters, including the geometric properties of the structure as well as the properties of the electrical circuit on the resulting power. Furthermore, the effect of length scale parameters on the harvested energy is investigated in detail. It is observed that the predictions of classical and even simple size-dependent theories (such as couple stress) appreciably differ from the findings of strain gradient theory on the basis of random vibration. This study presents a first-time modeling of micro-scale harvesters under stochastic excitations using a size-dependent approach and can be considered as a reliable foundation for future research in the field of
Tajti, Attila; Szalay, Péter G
2016-11-08
Describing electronically excited states of molecules accurately poses a challenging problem for theoretical methods. Popular second order techniques like Linear Response CC2 (CC2-LR), Partitioned Equation-of-Motion MBPT(2) (P-EOM-MBPT(2)), or Equation-of-Motion CCSD(2) (EOM-CCSD(2)) often produce results that are controversial and are ill-balanced with their accuracy on valence and Rydberg type states. In this study, we connect the theory of these methods and, to investigate the origin of their different behavior, establish a series of intermediate variants. The accuracy of these on excitation energies of singlet valence and Rydberg electronic states is benchmarked on a large sample against high-accuracy Linear Response CC3 references. The results reveal the role of individual terms of the second order similarity transformed Hamiltonian, and the reason for the bad performance of CC2-LR in the description of Rydberg states. We also clarify the importance of the T̂ 1 transformation employed in the CC2 procedure, which is found to be very small for vertical excitation energies.
International Nuclear Information System (INIS)
Wang Guang-Qing; Liao Wei-Hsin
2015-01-01
This work focuses on how to maintain a high-energy orbit motion of a bistable oscillator when subjected to a low level excitation. An elastic magnifier (EM) positioned between the base and the bistable oscillator is used to magnify the base vibration displacement to significantly enhance the output characteristics of the bistable oscillator. The dimensionless electromechanical equations of the bistable oscillator with an EM are derived, and the effects of the mass and stiffness ratios between the EM and the bistable oscillator on the output displacement are studied. It is shown that the jump phenomenon occurs at a lower excitation level with increasing the mass and stiffness ratios. With the comparison of the displacement trajectories and the phase portraits obtained from experiments, it is validated that the bistable oscillator with an EM can effectively oscillate in a high-energy orbit and can generate a superior output vibration at a low excitation level as compared with the bistable oscillator without an EM. (paper)
Theoretical study of cylindrical energy analyzers for MeV range heavy ion beam probes
International Nuclear Information System (INIS)
Fujisawa, A.; Hamada, Y.
1993-07-01
A cylindrical energy analyzer with drift spaces is shown to have a second order focusing for beam incident angle when the deflection angle is properly chosen. The analyzer has a possibility to be applied to MeV range heavy ion beam probes, and will be also available for accurate particle energy measurements in many other fields. (author)
Deuteron stripping on beryllium target in the 100-2300 MeV energy range
International Nuclear Information System (INIS)
Lecolley, J.F.; Varignon, C.; Durand, D.; Le Brun, C.; Lecolley, F.R.; Lefebvres, F.; Louvel, M.; Thun, J.; Borne, F.; Martinez, E.; Menard, S.; Pras, P.; Boudard, A.; Duchazeaubeneix, J.C.; Durand, J.M.; Frehaut, J.; Hanappe, F.; Ledoux, X.; Legrain, R.; Leray, S.; Milleret, G.; Patin, Y.; Stuttge, L.; Terrien, Y.
1999-01-01
Cross sections for stripping and dissociation of deuterons interacting with Be targets in the 100-2300 MeV energy range have been measured. Comparisons with model calculations suggest a dominant contribution of the stripping process. It is also shown that the deuteron break-up cross section exhibits the same energy dependence as the nucleon-nucleon cross section. (orig.)
International Nuclear Information System (INIS)
Patnaik, R.; Patra, R.; Satpathy, L.
1975-01-01
For even-even nuclei, the excitation energy E2 and the reduced transition probability B (E2) between the ground state and the first excited 2 + state have been considered. On the basis of different models, it is shown that for a nucleus N, Z the relations E2N, Z + E2N + 2,Z + 2 - E2N + 2, Z - E2N, Z + 2 approx. = 0 and B (E2)N, Z + B (E2)N + 2,Z + 2 - B (E2)N + 2,Z - B (E2)N, Z + 2 approx. = 0 hold good, except in certain specified regions. The goodness of these difference equations is tested with the available experimental data. The difference equation of Ross and Bhaduri is shown to follow from our approach. Some predictions of unmeasured E2 and B (E2) values have been made
Brøndsted Nielsen, Steen; Brøndsted Nielsen, Mogens; Rubio, Angel
2014-04-15
In a charge-transfer (CT) transition, electron density moves from one end of the molecule (donor) to the other end (acceptor). This type of transition is of paramount importance in nature, for example, in photosynthesis, and it governs the excitation of several protein biochromophores and luminophores such as the oxyluciferin anion that accounts for light emission from fireflies. Both transition energy and oscillator strength are linked to the coupling between the donor and acceptor groups: The weaker the coupling, the smaller the excitation energy. But a weak coupling necessarily also causes a low oscillator strength possibly preventing direct excitation (basically zero probability in the noncoupling case). The coupling is determined by the actual spacer between the two groups, and whether the spacer acts as an insulator or a conductor. However, it can be difficult or even impossible to distinguish the effect of the spacer from that of local solvent molecules that often cause large solvent shifts due to different ground-state and excited-state stabilization. This calls for gas-phase spectroscopy experiments where absorption by the isolated molecule is identified to unequivocally establish the intrinsic molecular properties with no perturbations from a microenvironment. From such insight, the effect of a protein microenvironment on the CT excited state can be deduced. In this Account, we review our results over the last 5 years from mass spectroscopy experiments using specially designed apparatus on several charged donor-acceptor ions that are based on the nitrophenolate moiety and π-extended derivatives, which are textbook examples of donor-acceptor chromophores. The phenolate oxygen is the donor, and the nitro group is the acceptor. The choice of this system is also based on the fact that phenolate is a common structural motif of biochromophores and luminophores, for example, it is a constituent of the oxyluciferin anion. A presentation of the setups used for
Low-energy excitations of the correlation-gap insulator SmB6: A light-scattering study
International Nuclear Information System (INIS)
Nyhus, P.; Cooper, S.L.; Fisk, Z.; Sarrao, J.
1997-01-01
We present the results of Raman scattering studies of single-crystal SmB 6 for temperatures down to 4 K and in magnetic fields up to 8 T. At temperatures below T * ∼50K the electronic Raman continuum exhibits an abrupt redistribution of scattering intensity around a temperature-independent (open-quotes isobesticclose quotes) energy, Δ c ∼290cm -1 , reflecting the opening of a pseudogap which is larger than previously suggested by transport measurements. Additionally, the Raman response exhibits at least four well-defined excitations within the gap below T * . The field dependencies of some of these in-gap states are consistent with the expected g factor (g eff =2/7) for the Sm 3+ Γ 8 level, suggesting that these gap edge states are crystal-electric-field excitations of the Sm 3+ ion split by magnetoelastic coupling. copyright 1997 The American Physical Society
Molotokaite, Egle; Remelli, William; Casazza, Anna Paola; Zucchelli, Giuseppe; Polli, Dario; Cerullo, Giulio; Santabarbara, Stefano
2017-10-26
The dynamics of excited state equilibration and primary photochemical trapping have been investigated in the photosystem I-light harvesting complex I isolated from spinach, by the complementary time-resolved fluorescence and transient absorption approaches. The combined analysis of the experimental data indicates that the excited state decay is described by lifetimes in the ranges of 12-16 ps, 32-36 ps, and 64-77 ps, for both detection methods, whereas faster components, having lifetimes of 550-780 fs and 4.2-5.2 ps, are resolved only by transient absorption. A unified model capable of describing both the fluorescence and the absorption dynamics has been developed. From this model it appears that the majority of excited state equilibration between the bulk of the antenna pigments and the reaction center occurs in less than 2 ps, that the primary charge separated state is populated in ∼4 ps, and that the charge stabilization by electron transfer is completed in ∼70 ps. Energy equilibration dynamics associated with the long wavelength absorbing/emitting forms harbored by the PSI external antenna are also characterized by a time mean lifetime of ∼75 ps, thus overlapping with radical pair charge stabilization reactions. Even in the presence of a kinetic bottleneck for energy equilibration, the excited state dynamics are shown to be principally trap-limited. However, direct excitation of the low energy chlorophyll forms is predicted to lengthen significantly (∼2-folds) the average trapping time.
Mechanism of long-range penetration of low-energy ions in botanic samples
International Nuclear Information System (INIS)
Liu Feng; Wang Yugang; Xue Jianming; Wang Sixue; Du Guanghua; Yan Sha; Zhao Weijiang
2002-01-01
The authors present experimental evidence to reveal the mechanism of long-range penetration of low-energy ions in botanic samples. In the 100 keV Ar + ion transmission measurement, the result confirmed that low-energy ions could penetrate at least 60 μm thick kidney bean slices with the probability of about 1.0 x 10 -5 . The energy spectrum of 1 MeV He + ions penetrating botanic samples has shown that there is a peak of the count of ions with little energy loss. The probability of the low-energy ions penetrating the botanic sample is almost the same as that of the high-energy ions penetrating the same samples with little energy loss. The results indicate that there are some micro-regions with mass thickness less than the projectile range of low-energy ions in the botanic samples and they result in the long-range penetration of low-energy ions in botanic samples
Alpha Beam Energy Determination Using a Range Measuring Device for Radioisotope Production
Energy Technology Data Exchange (ETDEWEB)
Choi, Jun Yong; Kim, Byeon Gil; Hong, Seung Pyo; Kim, Ran Young; Chun, Kwon Soo [Korea Institute of Radiological and Medical Sciences, Seoul (Korea, Republic of)
2016-05-15
The threshold energy of the {sup 209}Bi(α,3n){sup 210} At reaction is at about 30MeV. Our laboratory suggested an energy measurement method to confirm the proton-beam's energy by using a range measurement device. The experiment was performed energy measurement of alpha beam. The alpha beam of energy 29 MeV has been extracted from the cyclotron for the production of {sup 211}At. This device was composed of four parts: an absorber, a drive shaft, and a servo motor and a Faraday cup. The drive shaft was mounted on the absorber and connects with the axis of the servo motor and rotates linearly and circularly by this servo motor. A Faraday cup is for measuring the beam flux. As this drive shaft rotates, the thickness of the absorber varies depending on the rotation angle of the absorber. The energy of the alpha particle accelerated and extracted from MC-50 cyclotron was calculated with the measurement of the particle range in Al foil and using ASTAR, SRIM, MCNPX software. There were a little discrepancy between the expected energy and the calculated energy within the 0.5MeV error range. We have a plan to make an experiment with various alpha particle energies and another methodology, for example, the cross section measurement of the nuclear reaction.
Viaggiu, S.
2018-04-01
In this paper, we continue the investigations present in Refs. 1-3. In particular, we extend the theorem proved in Ref. 3 to any massless excitation in a given spherical box. As a first interesting result, we show that it is possible, contrary to the black hole case studied in detail in Refs. 1-3, to build macroscopic configurations with a dark energy equation of state. To this purpose, by requiring a stable configuration, a macroscopic dark fluid is obtained with an internal energy U scaling as the volume V, but with a fundamental correction looking like ˜ 1/R motivated by quantum fluctuations. Thanks to the proposition in Sec. 3 (and in Ref. 3 for gravitons), one can depict the dark energy in terms of massless excitations with a discrete spectrum. This fact opens the possibility to test a possible physical mechanism converting usual radiation into dark energy in a macroscopic configuration, also in a cosmological context. In fact, for example, in a Friedmann flat universe with a cosmological constant, particles are marginally trapped at the Hubble horizon for any given comoving observer.
Performance tests of a special ionization chamber for X-rays in mammography energy range
Energy Technology Data Exchange (ETDEWEB)
Silva, J.O., E-mail: jonas.silva@ufg.br [Universidade Federal de Goiás (UFG), Goiânia (Brazil). Instituto de Física; Caldas, L.V.E. [Instituto de Pesquisas Energéticas e Nucleares (IPEN-CNEN/SP), São Paulo, SP (Brazil). Centro de Metrologia das Radiações
2017-07-01
A special mammography homemade ionization chamber was developed to be applied for mammography energy range dosimetry. This chamber has a total sensitive volume of 6 cm{sup 3} and is made of a PMMA body and graphite coated collecting electrode. Performance tests as saturation, ion collection efficiency, linearity of chamber response versus air kerma rate and energy dependence were determined. The results obtained with this special homemade ionization chamber are within the limits stated in international recommendations. This chamber can be used in quality control programs of mammography energy range. All measurements were carried out at the Calibration Laboratory of IPEN. (author)
Energy Technology Data Exchange (ETDEWEB)
Barati, Ali [Faculty of Chemistry, Institute for Advanced Studies in Basic Sciences, Zanjan (Iran, Islamic Republic of); Department of Chemistry, Razi University, Kermanshah (Iran, Islamic Republic of); Shamsipur, Mojtaba, E-mail: mshamsipur@yahoo.com [Department of Chemistry, Razi University, Kermanshah (Iran, Islamic Republic of); Abdollahi, Hamid, E-mail: abd@iasbs.ac.ir [Faculty of Chemistry, Institute for Advanced Studies in Basic Sciences, Zanjan (Iran, Islamic Republic of)
2016-08-10
In this study, preparation of novel pH-sensitive N-doped carbon dots (NCDs) using glucose and urea is reported. The prepared NCDs present strong excitation-dependent fluorescence changes towards the pH that is a new behavior from these nanomaterials. By taking advantage of this unique behavior, two separated ratiometric pH sensors using emission spectra of the NCDs for both acidic (pH 2.0 to 8.0) and basic (pH 7.0 to 14.0) ranges of pH are constructed. Additionally, by considering the entire Excitation–Emission Matrix (EEM) of NCDs as analytical signal and using a suitable multivariate calibration method, a broad range of pH from 2.0 to 14.0 was well calibrated. The multivariate calibration method was independent from the concentration of NCDs and resulted in a very low average prediction error of 0.067 pH units. No changes in the predicted pH under UV irradiation (for 3 h) and at high ionic strength (up to 2 M NaCl) indicated the high stability of this pH nanosensor. The practicality of this pH nanosensor for pH determination in real water samples was validated with good accuracy and repeatability. - Highlights: • Novel pH-sensitive carbon dots with strong FL changes towards pH are reported. • Ratiometric FL pH-sensors for both acidic and basic ranges of pH are constructed. • Multivariate calibration methods were used to calibrate a broad range of pH. • Using EEM of carbon dots and ANN, pH from 2.0 to 14.0 was well calibrated. • The pH prediction is stable even at high ionic strength up to 2 M NaCl.
International Nuclear Information System (INIS)
Barati, Ali; Shamsipur, Mojtaba; Abdollahi, Hamid
2016-01-01
In this study, preparation of novel pH-sensitive N-doped carbon dots (NCDs) using glucose and urea is reported. The prepared NCDs present strong excitation-dependent fluorescence changes towards the pH that is a new behavior from these nanomaterials. By taking advantage of this unique behavior, two separated ratiometric pH sensors using emission spectra of the NCDs for both acidic (pH 2.0 to 8.0) and basic (pH 7.0 to 14.0) ranges of pH are constructed. Additionally, by considering the entire Excitation–Emission Matrix (EEM) of NCDs as analytical signal and using a suitable multivariate calibration method, a broad range of pH from 2.0 to 14.0 was well calibrated. The multivariate calibration method was independent from the concentration of NCDs and resulted in a very low average prediction error of 0.067 pH units. No changes in the predicted pH under UV irradiation (for 3 h) and at high ionic strength (up to 2 M NaCl) indicated the high stability of this pH nanosensor. The practicality of this pH nanosensor for pH determination in real water samples was validated with good accuracy and repeatability. - Highlights: • Novel pH-sensitive carbon dots with strong FL changes towards pH are reported. • Ratiometric FL pH-sensors for both acidic and basic ranges of pH are constructed. • Multivariate calibration methods were used to calibrate a broad range of pH. • Using EEM of carbon dots and ANN, pH from 2.0 to 14.0 was well calibrated. • The pH prediction is stable even at high ionic strength up to 2 M NaCl.
Mean range and energy of 28Si ions some Makrofol track detectors
International Nuclear Information System (INIS)
Shyam, S.; Mishra, R.; Tripathy, S.P.; Mawar, A.K.; Dwivedi, K.K.; Khathing, D.T.; Srivastava, A.; Avasthi, D.K.
2000-01-01
The rate of energy loss of the impinging ion as it passes through succeeding layers of the target material gives information regarding the nature of material and helps to calculate the range of the ions in a thick target in which the ions are stopped. Here the range, energy loss of 118 MeV 28 Si were measured in Makrofol-N, Makrofol-G and Makrofol-KG, using nuclear track technique. The experimental range data are compared with the theoretical values obtained from different computer codes. (author)
International Nuclear Information System (INIS)
Grimes, R.M.
1986-11-01
To further understanding of gas phase collision dynamics involving electronically-excited molecules, a fully quantum mechanical study of He + H 2 (B 1 Σ/sub u/ + ) was undertaken. Iterative natural orbital configuration interaction (CI) calculations were performed to obtain the interaction potential between He and H 2 (B 1 Σ/sub u/ + ). The potential energy surface (PES) is highly anisotropic and has a van der Waals well of about 0.03 eV for C/sub 2v/ approach. Avoided PES crossings occur with He + H 2 (E,F 1 Σ/sub g/ + ) and with He + H 2 (X 1 Σ/sub g/ + ) and cause a local maximum and a deep minimum in the He + H 2 (B 1 Σ/sub u/ + ) PES, respectively. The crossing with He + H 2 (X 1 Σ/sub g/ + ) provides a mechanism for fluorescence quenching. The computed CI energies were combined with previous multi-reference double excitation CI calculations and fit with analytic functions for convenience in scattering calculations. Accurate dipole polarizabilities and quadrupole moment of H 2 (B 1 Σ/sub u/ + ) were computed for use in the multipole expansion, which is the analytic form of the long-range PES. 129 refs., 28 figs., 35 tabs
Energy Impacts of Effective Range Hood Use for all U.S. Residential Cooking
Energy Technology Data Exchange (ETDEWEB)
Logue, Jennifer M; Singer, Brett
2014-06-01
Range hood use during residential cooking is essential to maintaining good indoor air quality. However, widespread use will impact the energy demand of the U.S. housing stock. This paper describes a modeling study to determine site energy, source energy, and consumer costs for comprehensive range hood use. To estimate the energy impacts for all 113 million homes in the U.S., we extrapolated from the simulation of a representative weighted sample of 50,000 virtual homes developed from the 2009 Residential Energy Consumption Survey database. A physics-based simulation model that considered fan energy, energy to condition additional incoming air, and the effect on home heating and cooling due to exhausting the heat from cooking was applied to each home. Hoods performing at a level common to hoods currently in U.S. homes would require 19?33 TWh [69?120 PJ] of site energy, 31?53 TWh [110-190 PJ] of source energy; and would cost consumers $1.2?2.1 billion (U.S.$2010) annually in the U.S. housing stock. The average household would spend less than $15 annually. Reducing required airflow, e.g. with designs that promote better pollutant capture has more energy saving potential, on average, than improving fan efficiency.
International Nuclear Information System (INIS)
Pan, Jie; Jiang, Lijun; Chan, Chi-Fai; Tsoi, Tik-Hung; Shiu, Kwok-Keung; Kwong, Daniel W.J.; Wong, Wing-Tak; Wong, Wai-Kwok; Wong, Ka-Leung
2017-01-01
Porphyrins are good photodynamic therapy (PDT) agents due to its flexibility for modifications to achieve tumor localization and photo-cytotoxicity against cancer. Yet they are not perfect. In a Ru(polypyridyl)-porphyrin system, the Ru(polypyridyl) moiety improves the water solubility and cell permeability. Consider the similar excited state energies between Ru(polypyridyl) and porphyrin moieties; a small perturbation (e.g. Zn(II) metalation) would lead to a marked change in the energy migration process. In this work, we have synthesized a series of porphyrins conjugated with Ru(polypyridyl) complexes using different linkers and investigated their photophysical properties, which included singlet oxygen quantum yield and their in vitro biological properties, resulting from linker variation and porphyrin modification by Zn(II) metalation. - Graphical abstract: Four amphiphilic ruthenium(II)-porphyrin complexes were prepared that display energy transfer conversion with zinc coordination, lysosome specific target, low dark toxicity and efficient photodynamic therapy.
Energy-Efficient Algorithm for Sensor Networks with Non-Uniform Maximum Transmission Range
Directory of Open Access Journals (Sweden)
Yimin Yu
2011-06-01
Full Text Available In wireless sensor networks (WSNs, the energy hole problem is a key factor affecting the network lifetime. In a circular multi-hop sensor network (modeled as concentric coronas, the optimal transmission ranges of all coronas can effectively improve network lifetime. In this paper, we investigate WSNs with non-uniform maximum transmission ranges, where sensor nodes deployed in different regions may differ in their maximum transmission range. Then, we propose an Energy-efficient algorithm for Non-uniform Maximum Transmission range (ENMT, which can search approximate optimal transmission ranges of all coronas in order to prolong network lifetime. Furthermore, the simulation results indicate that ENMT performs better than other algorithms.
Nonlinear ionization of many-electron systems over a broad photon-energy range
International Nuclear Information System (INIS)
Karamatskou, Antonia
2015-11-01
Rapid developments in laser technology and, in particular, the advances in the realm of free-electron lasers have initiated tremendous progress in both theoretical and experimental atomic, molecular and optical physics. Owing to high intensities in combination with short pulse durations we can enter the utterly nonlinear regime of light-matter interaction and study the dynamics and features of matter under extreme conditions. The capabilities of X-ray free-electron laser sources have promoted the importance of nonlinear optics also in the X-ray regime. I show in my thesis how we can exploit the nonlinear response regime to reveal hidden information about resonance structures that are not resolved in the weak-field regime. This prospect points to many applications for future investigations of various complex systems with free-electron lasers. In the present thesis the interaction of atomic closed-shell systems with ultrashort and strong laser pulses is investigated. Over a broad photon-energy range the characteristics of the atomic shell are studied with a particular focus on the nonlinear response regime and on electron correlation effects. Several computational extensions of the XCID package for multi-electron dynamics are presented and their applications in various studies are demonstrated; a completely new capability of the numerical method is realized by implementing the calculation of photoelectron spectra and by calculating eigenstates of the many-electron Hamiltonian. The field of study within the present work encompasses (1) the strong-field regime, where the question of the adiabatic character in tunneling ionization is discussed and analyzed, especially for the case of few-cycle pulses; (2) the XUV regime, in which we show for the first time that the collectivity in resonant excitation reveals new information; and (3) the (hard) x-ray regime, which is highly relevant for x-ray free-electron laser experiments, and where we show how important two
Energy Technology Data Exchange (ETDEWEB)
Dantz, Marcus; Pelliciari, Jonathan; Huang, Yaobo; Bisogni, Valentina; Olalde-Velasco, Paul; Strocov, Vladimir; Schmitt, Thorsten [Paul Scherrer Institut, Villigen PSI (Switzerland); Samal, Debakanta; Koster, Gertjan [MESA+ Institute for Nanotechnology, University of Twente (Netherlands)
2015-07-01
Multi-layered thin cuprate films allow inducing subtle structural changes with which local crystal field and long range magnetic excitations can be finely tuned. In (SrCuO{sub 2}){sub n}/(SrTiO{sub 2}){sub 2} cuprate superlattices, in particular, a structural transformation from a bulk infinite planar to a sheet-like local domain environment has recently been predicted and subsequently observed. Here we present results on the influence of this subtle structural reconstruction on the collective magnetic excitations using high-resolution resonant inelastic x-ray scattering (RIXS) at the Cu L{sub 3} edge. While bulk like infinite layer films exhibit magnon excitations throughout the whole Brillouin zone, decreasing the thickness of the cuprate layers leads to quenching of the magnons starting from the Gamma point successively to the zone boundary, allowing us to study the coherence length of the collective long range magnetic excitations in these cuprate superlattices.
Janke, Svenja M; Auerbach, Daniel J; Wodtke, Alec M; Kandratsenka, Alexander
2015-09-28
We have constructed a potential energy surface (PES) for H-atoms interacting with fcc Au(111) based on fitting the analytic form of the energy from Effective Medium Theory (EMT) to ab initio energy values calculated with density functional theory. The fit used input from configurations of the H-Au system with Au atoms at their lattice positions as well as configurations with the Au atoms displaced from their lattice positions. It reproduces the energy, in full dimension, not only for the configurations used as input but also for a large number of additional configurations derived from ab initio molecular dynamics (AIMD) trajectories at finite temperature. Adiabatic molecular dynamics simulations on this PES reproduce the energy loss behavior of AIMD. EMT also provides expressions for the embedding electron density, which enabled us to develop a self-consistent approach to simulate nonadiabatic electron-hole pair excitation and their effect on the motion of the incident H-atoms. For H atoms with an energy of 2.7 eV colliding with Au, electron-hole pair excitation is by far the most important energy loss pathway, giving an average energy loss ≈3 times that of the adiabatic case. This increased energy loss enhances the probability of the H-atom remaining on or in the Au slab by a factor of 2. The most likely outcome for H-atoms that are not scattered also depends prodigiously on the energy transfer mechanism; for the nonadiabatic case, more than 50% of the H-atoms which do not scatter are adsorbed on the surface, while for the adiabatic case more than 50% pass entirely through the 4 layer simulation slab.
Prediction of the metabolizable energy requirements of free-range laying hens.
Brainer, M M A; Rabello, C B V; Santos, M J B; Lopes, C C; Ludke, J V; Silva, J H V; Lima, R A
2016-01-01
This experiment was conducted with the aim of estimating the ME requirements of free-range laying hens for maintenance, weight gain, and egg production. These experiments were performed to develop an energy requirement prediction equation by using the comparative slaughter technique and the total excreta collection method. Regression equations were used to relate the energy intake, the energy retained in the body and eggs, and the heat production of the hens. These relationships were used to determine the daily ME requirement for maintenance, the efficiency energy utilization above the requirements for maintenance, and the NE requirement for maintenance. The requirement for weight gain was estimated from the energy content of the carcass, and the diet's efficiency energy utilization was determined from the weight gain, which was measured during weekly slaughter. The requirement for egg production was estimated by considering the energy content of the eggs and the efficiency of energy deposition in the eggs. The requirement and efficiency energy utilization for maintenance were 121.8 kcal ME/(kg∙d)and 0.68, respectively. Similarly, the NE requirement for maintenance was 82.4 kcal ME/(kg∙d), and the efficiency energy utilization above maintenance was 0.61. Because the carcass body weight and energy did not increase during the trial, the weight gain could not be estimated. The requirements for egg production requirement and efficiency energy utilization for egg production were 2.48 kcal/g and 0.61, respectively. The following energy prediction equation for free-range laying hens (without weight gain) was developed: ME /(hen ∙ d) = 121.8 × W + 2.48 × EM, in which W = body weight (kg) and EM = egg mass (g/[hen ∙ d]).
Directory of Open Access Journals (Sweden)
Meng Chen
2018-04-01
Full Text Available Squeal noise often occurs in a two-stage electrohydraulic servo-valve, which is an unfavorable issue of modern hydraulic energy systems. The root causes of such noise from the servo-valve are still unclear. The objective of this paper is to explore the noise mechanism in a servo-valve excited by the pressure pulsations from the hydraulic energy system perspective. The suppressing capability of squeal noise energy is investigated by changing the pressure pulsation frequency and natural frequency of the flapper-armature assembly. The frequencies of the pressure pulsations are adjusted by setting different speeds of the hydraulic pump varying from 10,400–14,400 rpm, and two flapper-armature assemblies with different armature lengths are used in the tested hydraulic energy system. The first eight vibration mode shapes and natural frequencies of the flapper-armature assembly are obtained by numerical modal analysis using two different armature lengths. The characteristics of pressure pulsations at the pump outlet and in the chamber of the flapper-nozzle valve, armature vibration and noise are tested and compared with the natural frequencies of the flapper-armature assembly. The results reveal that the flapper-armature assembly vibrates and makes the noise with the same frequencies as the pressure pulsations inside the hydraulic energy system. Resonance appears when the frequency of the pressure pulsations coincides with the natural frequency of the flapper-armature assembly. Therefore, it can be concluded that the pressure pulsation energy from the power supply may excite the vibration of the flapper-armature assembly, which may consequently cause the squeal noise inside the servo-valve. It is verified by the numerical simulations and experiments that setting the pressure pulsation frequencies different from the natural frequencies of the flapper-armature assembly can suppress the resonance and squeal noise.
Directory of Open Access Journals (Sweden)
Lei Huang
2013-01-01
Full Text Available Linear generators have the advantage of a simple structure of the secondary, which is suitable for the application of wave energy conversion. Based on the vernier hybrid machines (VHMs, widely used for direct drive wave energy converters, this paper proposes a novel hybrid excitation flux-switching generator (LHEFSG, which can effectively improve the performance of this kind of generators. DC hybrid excitation windings and multitooth structure were used in the proposed generator to increase the magnetic energy and overcome the disadvantages of easily irreversible demagnetization of VHMs. Firstly, the operation principle and structure of the proposed generator are introduced. Secondly, by using the finite element method, the no-load performance of the proposed generator is analyzed and composed with ones of conventional VHM. In addition, the on-load performance of the proposed generator is obtained by finite element analysis (FEA. A dislocation of pole alignments method is implemented to reduce the cogging force. Lastly, a prototype of the linear flux-switching generator is used to verify the correctness of FEA results. All the results validate that the proposed generator has better performance than its counterparts.
Charge transfer in low-energy collisions of H with He+ and H+ with He in excited states
Loreau, J.; Ryabchenko, S.; Muñoz Burgos, J. M.; Vaeck, N.
2018-04-01
The charge transfer process in collisions of excited (n = 2, 3) hydrogen atoms with He+ and in collisions of excited helium atoms with H+ is studied theoretically. A combination of a fully quantum-mechanical method and a semi-classical approach is employed to calculate the charge-exchange cross sections at collision energies from 0.1 eV u‑1 up to 1 keV u‑1. These methods are based on accurate ab initio potential energy curves and non-adiabatic couplings for the molecular ion HeH+. Charge transfer can occur either in singlet or in triplet states, and the differences between the singlet and triplet spin manifolds are discussed. The dependence of the cross section on the quantum numbers n and l of the initial state is demonstrated. The isotope effect on the charge transfer cross sections, arising at low collision energy when H is substituted by D or T, is investigated. Rate coefficients are calculated for all isotopes up to 106 K. Finally, the impact of the present calculations on models of laboratory plasmas is discussed.
Towards limits of excitation energy in the reaction 3He(1.8 GeV) + natAg
International Nuclear Information System (INIS)
Pollacco, E.C.; Brzychczyk, J.; Volant, C.; Legrain, R.; Nalpas, L.; Bracken, D.S.; Kwiatkowski, K.; Morley, K.B.; Foxford, E.R.; Viola, V.E.; Yoder, N.R.
1996-03-01
Hot nuclei are studied, where through an appropriate choice of incident channel and event selection, dynamical effects are attenuated and multifragmentation is limited. Three preparatory results are given, the 3 He(1.8 GeV) + nat Ag can be described using an intranuclear cascade, INC, model; through a suitable selection of events a limit of the excitation energy that a nucleus can absorb without breaking into large pieces is given, it is shown that corresponding alpha decay is consistent with an evaporative process. (K.A.)
International Nuclear Information System (INIS)
Broda, R.
1980-01-01
The experimental results are presented indicating the existence of the energy gap in the single particle level sequence at proton number Z=64. Studied experimentally yrast states of the 64 146 Gd 82 closed core nucleus and of the neighbouring nuclei are interpreted within the framework of the spherical shell model. The consideration of the simple shell model multiparticle configurations is suggested to explain the observed frequent appearance of the high-spin isomers in nuclei of the A approximately 150 region. Emphasized is the role of the octupole excitations in the level structures of considered nuclei and some aspects of the coupling of octupole vibrations with valence nucleons are discussed. (author)
International Nuclear Information System (INIS)
Mukhopadhyay, N.C.
1986-01-01
The status of the theory of the low-energy approach to hadron structure is reviewed briefly by surveying a few relevant models. A few examples of tests needed to sort out the predictions of different models pertaining to the quark-gluon structure of hadrons are discussed, and given the resulting physics objectives, a few experimental options for excited baryon research at CFBAF are suggested
Energy Technology Data Exchange (ETDEWEB)
Mukhopadhyay, N.C.
1986-01-01
The status of the theory of the low-energy approach to hadron structure is reviewed briefly by surveying a few relevant models. A few examples of tests needed to sort out the predictions of different models pertaining to the quark-gluon structure of hadrons are discussed, and given the resulting physics objectives, a few experimental options for excited baryon research at CFBAF are suggested. (LEW)
Gamma-ray astronomy in the medium energy (10-50 MeV) range
International Nuclear Information System (INIS)
Kniffen, D.A.; Bertsch, D.L.; Palmeira, R.A.R.; Rao, K.R.
1977-01-01
Gamma-ray astronomy in the medium energy (10-50 MeV) range can provide unique information with which to study many astrophysical problems. Observations in the 10-50 MeV range provide the cleanest window with which to view the isotropic diffuse component of the radiation and to study the possible cosmological implications of the spectrum. For the study of compact sources, this is the important region between the X-ray sky and the vastly different γ-ray sky seen by SAS-2 and COS-B. To understand the implications of medium energy γ-ray astronomy to the study of the galactic diffuse γ-radiation, the model developed to explain the high energy γ-ray observations of SAS-2 is extended to the medium energy range. This work illustrates the importance of medium energy γ-ray astronomy for studying the electromagnetic component of the galactic cosmic rays. To observe the medium energy component of the intense galactic center γ-ray emission, two balloon flights of a medium energy γ-ray spark chamber telescope were flown in Brazil in 1975. These results indicate the emission is higher than previously thought and above the predictions of the theoretical model
International Nuclear Information System (INIS)
Oppermann, R.; Rosenow, B.
1997-10-01
We report large effects of Parisi replica permutation symmetry breaking (RPSB) on elementary excitations of fermionic systems with frustrated magnetic interactions. The electronic density of states is obtained exactly in the zero temperature limit for (K = 1)- step RPSB together with relations for arbitrary breaking K, which lead to a new fermionic and dynamical Parisi solution at K = ∞. The Ward identity for charge conservation indicates RPSB-effects on the conductivity in metallic quantum spin glasses. This implies that RPSB is essential for any fermionic system showing spin glass sections within its phase diagram. An astonishing similarity with a neural network problem is also observed. (author)
Spin-orbit excitation energies, anisotropic exchange, and magnetic phases of honeycomb RuCl3
Yadav, Ravi; Bogdanov, Nikolay A.; Katukuri, Vamshi M.; Nishimoto, Satoshi; Brink, Jeroen van den; Hozoi, Liviu
2016-01-01
Large anisotropic exchange in 5d and 4d oxides and halides open the door to new types of magnetic ground states and excitations, inconceivable a decade ago. A prominent case is the Kitaev spin liquid, host of remarkable properties such as protection of quantum information and the emergence of Majorana fermions. Here we discuss the promise for spin-liquid behavior in the 4d 5 honeycomb halide ?-RuCl3. From advanced electronic-structure calculations, we find that the Kitaev interaction is ferro...
Energy System Expectations for Nuclear in the 21. Century: A Plausible Range
International Nuclear Information System (INIS)
Langlois, Lucille M.; McDonald, Alan; Rogner, Hans-Holger; Vera, Ivan
2002-01-01
This paper outlines a range of scenarios describing what the world's energy system might look like in the middle of the century, and what nuclear energy's most profitable role might be. The starting point is the 40 non-greenhouse-gas-mitigation scenarios in the Special Report on Emissions Scenarios (SRES) of the Intergovernmental Panel on Climate Change (IPCC, 2000). Given their international authorship and comprehensive review by governments and scientific experts, the SRES scenarios are the state of the art in long-term energy scenarios. However, they do not present the underlying energy system structures in enough detail for specific energy technology and infrastructure analyses. This paper therefore describes initial steps within INPRO (The International Project on Innovative Nuclear Reactors and Fuel Cycles of the International Atomic Energy Agency) to translate the SRES results into a range of possible nuclear energy technology requirements for mid-century. The paper summarizes the four SRES scenarios that will be used in INPRO and the reasons for their selection. It provides illustrative examples of the sort of additional detail that is being developed about the overall energy system implied by each scenario, and about specific scenario features particularly relevant to nuclear energy. As recommended in SRES, the selected scenarios cover all four SRES 'story-line families'. The energy system translations being developed in INPRO are intended to indicate how energy services may be provided in mid-century and to delineate likely technology and infrastructure implications. They will indicate answers to questions like the following. The list is illustrative, not comprehensive. - What kind of nuclear power plants will best fit the mid-century energy system? - What energy forms and other products and services provided by nuclear reactors will best fit the mid-century energy system? - What would be their market shares? - How difficult will it be to site new nuclear
Energy Flow Exciting Field-Aligned Current at Substorm Expansion Onset
Ebihara, Y.; Tanaka, T.
2017-12-01
At substorm expansion onset, upward field-aligned currents (FACs) increase abruptly, and a large amount of electromagnetic energy starts to consume in the polar ionosphere. A question arises as to where the energy comes from. Based on the results obtained by the global magnetohydrodynamics simulation, we present energy flow and energy conversion associated with the upward FACs that manifest the onset. Our simulations show that the cusp/mantle region transmits electromagnetic energy to almost the entire region of the magnetosphere when the interplanetary magnetic field is southward. Integral curve of the Poynting flux shows a spiral moving toward the ionosphere, probably suggesting the pathway of electromagnetic energy from the cusp/mantle dynamo to the ionosphere. The near-Earth reconnection initiates three-dimensional redistribution of the magnetosphere. Flow shear in the near-Earth region results in the generation of the near-Earth dynamo and the onset FACs. The onset FACs are responsible to transport the electromagnetic energy toward the Earth. In the near-Earth region, the electromagnetic energy coming from the cusp/mantle dynamo is converted to the kinetic energy (known as bursty bulk flow) and the thermal energy (associated with high-pressure region in the inner magnetosphere). Then, they are converted to the electromagnetic energy associated with the onset FACs. A part of electromagnetic energy is stored in the lobe region during the growth phase. The release of the stored energy, together with the continuously supplied energy from the cusp/mantle dynamo, contributes to the energy supply to the ionosphere during the expansion phase.
Analysis for mass distribution of proton-induced reactions in intermediate energy range
Xiao Yu Heng
2002-01-01
The mass and charge distribution of residual products produced in the spallation reactions needs to be studied, because it can provide useful information for the disposal of nuclear waste and residual radioactivity generated by the spallation neutron target system. In present work, the Many State Dynamical Model (MSDM) is based on the Cascade-Exciton Model (CEM). The authors use it to investigate the mass distribution of Nb, Au and Pb proton-induced reactions in energy range from 100 MeV to 3 GeV. The agreement between the MSDM simulations and the measured data is good in this energy range, and deviations mainly show up in the mass range of 90 - 150 for the high energy proton incident upon Au and Pb
Investigation of the neutron-proton-interaction in the energy range from 20 to 50 MEV
International Nuclear Information System (INIS)
Wilczynski, J.
1984-07-01
In the framework of the investigation of the isospin singlet part of the nucleon-nucleon-interaction in the energy range below 100 MeV two experiments were conducted, which were selected by sensitivity calculations. At the Karlsruhe polarized neutron facility POLKA the analyzing powers Asub(y) and Asub(yy) of the elastic n vector-p- and n vector-p vector-scattering were measured in the energy range from 20 to 50 MeV. The results of this epxeriment are compared to older data. In the energy range from 20 to 50 MeV the new data were analyzed together with other selected data of the nucleon-nucleon-system in phase shift analyses. The knowledge of the isospin singlet phase shifts 1 P 1 and 3 D 3 was improved by the new data. (orig./HSI) [de
Directory of Open Access Journals (Sweden)
Mohamed E. A. Farrag
2014-01-01
Full Text Available Incentives, such as the Feed-in-tariff are expected to lead to continuous increase in the deployment of Small Scale Embedded Generation (SSEG in the distribution network. Self-Excited Induction Generators (SEIG represent a significant segment of potential SSEG. The quality of SEIG output voltage magnitude and frequency is investigated in this paper to support the SEIG operation for different network operating conditions. The dynamic behaviour of the SEIG resulting from disconnection, reconnection from/to the grid and potential operation in islanding mode is studied in detail. The local load and reactive power supply are the key factors that determine the SEIG performance, as they have significant influence on the voltage and frequency change after disconnection from the grid. Hence, the aim of this work is to identify the optimum combination of the reactive power supply (essential for self excitation of the SEIG and the active load (essential for balancing power generation and demand. This is required in order to support the SEIG operation after disconnection from the grid, during islanding and reconnection to the grid. The results show that the generator voltage and speed (frequency can be controlled and maintained within the statuary limits. This will enable safe disconnection and reconnection of the SEIG from/to the grid and makes it easier to operate in islanding mode.
Ion implantation range and energy deposition codes COREL, RASE4, and DAMG2
International Nuclear Information System (INIS)
Brice, D.K.
1977-07-01
The FORTRAN codes COREL, RASE4 and DAMG2 can be used to calculate quantities associated with ion implantation range and energy deposition distributions within an amorphous target, or for ions incident far from low index directions and planes in crystalline targets. RASE4 calculates the projected range, R/sub p/, the root mean square spread in the projected range, ΔR/sub p/, and the root mean square spread of the distribution perpendicular to the projected range ΔR/sub perpendicular to/. These parameters are calculated as a function of incident ion energy, E, and the instantaneous energy of the ion, E'. They are sufficient to determine the three dimensional spatial distribution of the ions in the target in the Gaussian approximation when the depth distribution is independent of the lateral distribution. RASE4 can perform these calculations for targets having up to four different component atomic species. The code COREL is a short, economical version of RASE4 which calculates the range and straggling variables for E' = 0. Its primary use in the present package is to provide the average range and straggling variables for recoiling target atoms which are created by the incident ion. This information is used by RASE4 in calculating the redistribution of deposited energy by the target atom recoils. The code DAMG2 uses the output from RASE4 to calculate the depth distribution of energy deposition into either atomic processes or electronic processes. With other input DAMG2 can be used to calculate the depth distribution of any energy dependent interaction between the incident ions and target atoms. This report documents the basic theory behind COREL, RASE4 and DAMG2, including a description of codes, listings, and complete instructions for using the codes, and their limitations
Tel, E.; Durgu, C.; Aktı, N. N.; Okuducu, Ş.
2010-06-01
Fusion serves an inexhaustible energy for humankind. Although there have been significant research and development studies on the inertial and magnetic fusion reactor technology, there is still a long way to go to penetrate commercial fusion reactors to the energy market. Tritium self-sufficiency must be maintained for a commercial power plant. For self-sustaining (D-T) fusion driver tritium breeding ratio should be greater than 1.05. So, the working out the systematics of ( n, t) reaction cross sections is of great importance for the definition of the excitation function character for the given reaction taking place on various nuclei at different energies. In this study, ( n, t) reactions for some structural fusion materials such as 27Al, 51V, 52Cr, 55Mn, and 56Fe have been investigated. The new calculations on the excitation functions of 27Al( n, t)25Mg, 51V( n, t)49Ti, 52Cr( n, t)50V, 55Mn( n, t)53Cr and 56Fe( n, t)54Mn reactions have been carried out up to 50 MeV incident neutron energy. In these calculations, the pre-equilibrium and equilibrium effects have been investigated. The pre-equilibrium calculations involve the new evaluated the geometry dependent hybrid model, hybrid model and the cascade exciton model. Equilibrium effects are calculated according to the Weisskopf-Ewing model. Also in the present work, we have calculated ( n, t) reaction cross-sections by using new evaluated semi-empirical formulas developed by Tel et al. at 14-15 MeV energy. The calculated results are discussed and compared with the experimental data taken from the literature.
International Nuclear Information System (INIS)
Mozolevski, I.E.
2001-01-01
We consider the splitting of the straight-ahead Boltzmann transport equation in the Boltzmann-Fokker-Planck equation, decomposing the differential cross-section into a singular part, corresponding to small energy transfer events, and in a regular one, which corresponds to large energy transfer. The convergence of implantation profile, nuclear and electronic energy depositions, calculated from the Boltzmann-Fokker-Planck equation, to the respective exact distributions, calculated from Monte-Carlo method, was exanimate in a large-energy interval for various values of splitting parameter and for different ion-target mass relations. It is shown that for the universal potential there exists an optimal value of splitting parameter, for which range and deposited energy distributions, calculated from the Boltzmann-Fokker-Planck equation, accurately approximate the exact distributions and which minimizes the computational expenses
Combined production of free-range pigs and energy crops – animal behaviour and crop damages
DEFF Research Database (Denmark)
Horsted, Klaus; Kongsted, Anne Grete; Jørgensen, Uffe
2012-01-01
Intensive free-range pig production on open grasslands has disadvantages in that it creates nutrient hotspots and little opportunity for pigs to seek shelter from the sun. Combining a perennial energy crop and pig production might benefit the environment and animal welfare because perennial energy...... crops like willow (Salix sp.) and Miscanthus offer the pigs protection from the sun while reducing nutrient leaching from pig excrements due to their deep rooting system. The objectives of this study were to evaluate how season and stocking density of pigs in a free-range system with zones of willow...
International Nuclear Information System (INIS)
Itkis, M.G.; Kalpakchieva, R.; Okolovich, V.N.; Penionzhkevich, Yu.Eh.; Tolstikov, V.N.
1982-01-01
To study characteristics of fissioning nucleus fragments, investigated were reactiiiiiiiiiiiiiiiH8Pt+ 12 C → 210 Po in the 12 C ion energy range of 86-110.5 MeV, of 192 Os+ 16 O → 208 Po in 90-131 MeV range, 204 Pb+ 3 He → 207 Po, 206 Pb+ 3 He → 209 Po, 207 Pb+ 3 He → 210 Po with 60 MeV 3 He ion energy. Using a correlation technique for measuring energies of two fragments mass and energy distributions of fission fragments of 208 Po and 210 Po compound nuclei produced in the reactions have been studied. Mass and energy distributions of fragments from fission of 208 Po and 210 Po in the reactions with ions 16 O, 12 C and 3 He were investigated in an ample energy range, using the correlational techniques for measurement of energies of two fragments. An increase in the total kinetic energy with rise of the angular momentum was observed, the fact indicating a weak coupling of one-particle and collective modes of motion in the fissile nucleus resulting in that the rolational energy is transfered mainly to translation energies of the fragments
International Nuclear Information System (INIS)
Safronova, University I.; Safronova, A. S.; Beiersdorfer, P.
2016-01-01
Energy levels, radiative transition probabilities, and autoionization rates for [Ni]4s 2 4p 6 nl, [Ni]4s 2 4p 5 4l ′ nl (l ′ =d,f,n = 4–7), [Ni]4s4p 6 4l ′ nl, (l ′ =d,f,n = 4–7), [Ni]4s 2 4p 5 5l ′ nl (n = 5–7), and [Ni]4s4p 6 6l ′ nl (n = 6–7) states in Rb-like tungsten (W37+) are calculated using the relativistic many-body perturbation theory method (RMBPT code) and the Hartree–Fock-relativistic method (COWAN code). Autoionizing levels above the [Ni]4s 2 4p 6 threshold are considered. It is found that configuration mixing among [Ni]4s 2 4p 5 4l ′ nl and [Ni]4s4p 6 4l ′ nl plays an important role for all atomic characteristics. Branching ratios relative to the first threshold and intensity factors are calculated for satellite lines, and dielectronic recombination (DR) rate coefficients are determined for the [Ni]4s 2 4p 6 nl (n = 4–7) singly excited states, as well as the [Ni]4s 2 4p 5 4dnl, [Ni]4s 2 4p 5 4fnl, [Ni]4s4p 6 4dnl, [Ni]4s 2 4p 6 4fnl, (n = 4–6), and [Ni]4s 2 4p 5 5l ′ 5l doubly excited nonautoionizing states in Rb-like W37+ ion. Contributions from the [Ni]4s24p 6 4fnl (n = 6–7), [Ni]4s 2 4p 5 5l ′ nl (n = 5–6), and [Ni]4s 2 4p 5 6l ′ nl (n = 6–7) doubly excited autoionizing states are evaluated numerically. The high-n state (with n up to 500) contributions are very important for high temperatures. These contributions are determined by using a scaling procedure. Synthetic dielectronic satellite spectra from Rb-like W are simulated in a broad spectral range from 8 to 70 Å. Here, these calculations provide highly accurate values for a number of W 37+ properties useful for a variety of applications including for fusion applications.
International Nuclear Information System (INIS)
Lautesse, Ph.
2005-11-01
The progress made in particle detection, particularly the design of multi-detectors, like INDRA, that cover a solid angle of almost 4π, have given a new impetus to heavy ion collisions. These detectors are demanding for an efficient way of selecting events that have a common history or similar features, for instance the events representing the de-excitation of a unique emitter. The problem is to find the adequate variable on which the discrimination can be based. Different methods are proposed in this work, the common point is that they require efficient models to reproduce and analyse experimental data in order to apprehend the equation of state of nuclear matter. Most of these models are based on the numerically solving of the nuclear Boltzmann equation. The application to the Ni + Ni reaction with an energy ranging from a few A.MeV to more than 50 A.MeV illustrates this work. (A.C.)
Ren, Xinguo; Rinke, Patrick; Tkatchenko, Alexandre; Scheffler, Matthias
2010-01-01
The random-phase approximation (RPA) for the electron correlation energy, combined with the exact-exchange (EX) energy, represents the state-of-the-art exchange-correlation functional within density-functional theory. However, the standard RPA practice-evaluating both the EX and the RPA correlation energies using Kohn-Sham (KS) orbitals from local or semilocal exchange-correlation functionals-leads to a systematic underbinding of molecules and solids. Here we demonstrate that this behavior ca...
Hyperon excitation in nuclear coulomb field
International Nuclear Information System (INIS)
Vanyashin, A.V.; Nikitin, Yu.P.; Shan'gin, A.A.
1981-01-01
A possibility is studied to measure radiative decay partial widths from the 3/2 + decuplet hyperon resonances by means of the Coulomb excitation method of the octet hyperons. The expected contributions from the strong and electromagnetic interactions in the coherence range to the hyperon excitation cross sections on heavy nuclei and on the 4 He nucleus are estimated. The particle angular distributions in the reactions Σ-+A→Σ-(1385)+A and Λ+A→Σ 0 (1385)+A are analysed in order to determine the energy range where the background conditions are the most favorable to extract the electromagnetic mechanism of the hyperon excitation [ru
Harnessing Big-Data for Estimating the Energy Consumption and Driving Range of Electric Vehicles
DEFF Research Database (Denmark)
Fetene, Gebeyehu Manie; Prato, Carlo Giacomo; Kaplan, Sigal
-effects econometrics model used in this paper predicts that the energy saving speed of driving is between 45 and 56 km/h. In addition to the contribution to the literature about energy efficiency of electric vehicles, the findings from this study enlightens consumers to choose appropriate cars that suit their travel......This study analyses the driving range and investigates the factors affecting the energy consumption rate of fully-battery electric vehicles under real-world driving patterns accounting for weather condition, drivers’ characteristics, and road characteristics. Four data sources are used: (i) up...
Search for solar Axion Like Particles in the low energy range at CAST
International Nuclear Information System (INIS)
Cantatore, G.; Karuza, M.; Lozza, V.; Raiteri, G.
2010-01-01
Axion Like Particles (ALPs) could be continuously produced in the Sun via the Primakoff process. The ALP flux could be seen on Earth by observing the photons produced by the ALP decay. The expected energy distribution of reconverted photons is peaked at 3 keV. There could be, however, a low energy tail due to various processes active in the Sun. We report results of the first test measurements in the low energy range performed at CAST along with a description of the experimental setup. Future detector developments are discussed and preliminary results on a liquid nitrogen cooled Avalanche Photodiode are presented.
A new ab initio potential energy surface for the collisional excitation of N2H+ by H2
International Nuclear Information System (INIS)
Spielfiedel, Annie; Balança, Christian; Feautrier, Nicole; Senent, Maria Luisa; Kalugina, Yulia; Scribano, Yohann; Lique, François
2015-01-01
We compute a new potential energy surface (PES) for the study of the inelastic collisions between N 2 H + and H 2 molecules. A preliminary study of the reactivity of N 2 H + with H 2 shows that neglecting reactive channels in collisional excitation studies is certainly valid at low temperatures. The four dimensional (4D) N 2 H + –H 2 PES is obtained from electronic structure calculations using the coupled cluster with single, double, and perturbative triple excitation level of theory. The atoms are described by the augmented correlation consistent triple zeta basis set. Both molecules were treated as rigid rotors. The potential energy surface exhibits a well depth of ≃2530 cm −1 . Considering this very deep well, it appears that converged scattering calculations that take into account the rotational structure of both N 2 H + and H 2 should be very difficult to carry out. To overcome this difficulty, the “adiabatic-hindered-rotor” treatment, which allows para-H 2 (j = 0) to be treated as if it were spherical, was used in order to reduce the scattering calculations to a 2D problem. The validity of this approach is checked and we find that cross sections and rate coefficients computed from the adiabatic reduced surface are in very good agreement with the full 4D calculations
A new ab initio potential energy surface for the collisional excitation of N2H(+) by H2.
Spielfiedel, Annie; Senent, Maria Luisa; Kalugina, Yulia; Scribano, Yohann; Balança, Christian; Lique, François; Feautrier, Nicole
2015-07-14
We compute a new potential energy surface (PES) for the study of the inelastic collisions between N2H(+) and H2 molecules. A preliminary study of the reactivity of N2H(+) with H2 shows that neglecting reactive channels in collisional excitation studies is certainly valid at low temperatures. The four dimensional (4D) N2H(+)-H2 PES is obtained from electronic structure calculations using the coupled cluster with single, double, and perturbative triple excitation level of theory. The atoms are described by the augmented correlation consistent triple zeta basis set. Both molecules were treated as rigid rotors. The potential energy surface exhibits a well depth of ≃2530 cm(-1). Considering this very deep well, it appears that converged scattering calculations that take into account the rotational structure of both N2H(+) and H2 should be very difficult to carry out. To overcome this difficulty, the "adiabatic-hindered-rotor" treatment, which allows para-H2(j = 0) to be treated as if it were spherical, was used in order to reduce the scattering calculations to a 2D problem. The validity of this approach is checked and we find that cross sections and rate coefficients computed from the adiabatic reduced surface are in very good agreement with the full 4D calculations.
Mid-range adiabatic wireless energy transfer via a mediator coil
International Nuclear Information System (INIS)
Rangelov, A.A.; Vitanov, N.V.
2012-01-01
A technique for efficient mid-range wireless energy transfer between two coils via a mediator coil is proposed. By varying the coil frequencies, three resonances are created: emitter–mediator (EM), mediator–receiver (MR) and emitter–receiver (ER). If the frequency sweeps are adiabatic and such that the EM resonance precedes the MR resonance, the energy flows sequentially along the chain emitter–mediator–receiver. If the MR resonance precedes the EM resonance, then the energy flows directly from the emitter to the receiver via the ER resonance; then the losses from the mediator are suppressed. This technique is robust against noise, resonant constraints and external interferences. - Highlights: ► Efficient and robust mid-range wireless energy transfer via a mediator coil. ► The adiabatic energy transfer is analogous to adiabatic passage in quantum optics. ► Wireless energy transfer is insensitive to any resonant constraints. ► Wireless energy transfer is insensitive to noise in the neighborhood of the coils.
International Nuclear Information System (INIS)
Malinina, L.V.; Alkhazov, G.D.; Augustyniak, W.
2001-01-01
A study of inelastic scattering of polarized 3.73 GeV/c deuterons on protons in the energy region of the Roper N* (1440) and the Δ(1232) resonances excitation has been performed in an exclusive experiment at LNS (Laboratoire National SATURNE, Saclay, France) using the SPES4-π setup. Tensor and vector analyzing powers of pion production for the reactions d+p→d+n+π + , d+p→d+p+π 0 , d+p→d+N+ππ have been measured as functions of the squared deuteron 4-momentum transfer t, of the effective mass of the subsystems (Nπ), (Nππ) and of the pion emission angle. A strong dependence of these analyzing powers upon the pion emission angle is observed. It is found that A yy values for the considered reaction channels are systematically larger than the known inclusive p(d,d')X world data at the nearest beam energy
Malinina, L V; Augustyniak, W; Boivin, M; Boyard, J L; Dahl, R; Drews, M; Ellegaard, C; Fahri, L; Gaarde, C; Hennino, T; Jourdain, J C; Kagarlis, M A; Kravtsov, A V; Künne, R A; Larsen, J C; Morsch, P; Mylnikov, V A; Orichtchin, E M; Perdrisat, C F; Piskunov, N M; Prokofiev, A N; Punjabi, V; Radvanyi, P; Ramstein, B; Razmyslovich, B V; Roy-Stephan, M; Sitnik, I M; Skousen, M; Strokovsky, E A; Tkach, I I; Tomasi-Gustafsson, E; Volkov, S S; Zhdanov, A A; Zupranski, P
2001-01-01
A study of inelastic scattering of polarized 3.73 GeV/c deuterons on protons in the energy region of the Roper N*(1440) and the {DELTA}(1232) resonances excitation has been performed in an exclusive experiment at LNS (Laboratoire National SATURNE, Saclay, France) using the SPES-{pi} setup.Tensor and vector analyzing powers of pion production for the reactions d + p {\\to} d + n + pi^{+}, d + p {\\to} d + p + pi^{0}, d + p {\\to} d + N + pi pi have been measured as functions of the squared deuteron 4-momentum transfer t, of the effective mass of the subsystems (N pi), (N pi pi) and of the pion emission angle. A strong dependence of these analyzing powers upon the pion emission angle is observed. It is found that A_{yy} values for the considered reaction channels are systematically larger than the known inclusive {p (d, d {\\prime}) X} world data at the nearest beam energy.
Energy Technology Data Exchange (ETDEWEB)
Ledermüller, Katrin; Schütz, Martin, E-mail: martin.schuetz@chemie.uni-regensburg.de [Institute of Physical and Theoretical Chemistry, University of Regensburg, Universitätsstraße 31, D-93040 Regensburg (Germany)
2014-04-28
A multistate local CC2 response method for the calculation of analytic energy gradients with respect to nuclear displacements is presented for ground and electronically excited states. The gradient enables the search for equilibrium geometries of extended molecular systems. Laplace transform is used to partition the eigenvalue problem in order to obtain an effective singles eigenvalue problem and adaptive, state-specific local approximations. This leads to an approximation in the energy Lagrangian, which however is shown (by comparison with the corresponding gradient method without Laplace transform) to be of no concern for geometry optimizations. The accuracy of the local approximation is tested and the efficiency of the new code is demonstrated by application calculations devoted to a photocatalytic decarboxylation process of present interest.
Ledermüller, Katrin; Schütz, Martin
2014-04-28
A multistate local CC2 response method for the calculation of analytic energy gradients with respect to nuclear displacements is presented for ground and electronically excited states. The gradient enables the search for equilibrium geometries of extended molecular systems. Laplace transform is used to partition the eigenvalue problem in order to obtain an effective singles eigenvalue problem and adaptive, state-specific local approximations. This leads to an approximation in the energy Lagrangian, which however is shown (by comparison with the corresponding gradient method without Laplace transform) to be of no concern for geometry optimizations. The accuracy of the local approximation is tested and the efficiency of the new code is demonstrated by application calculations devoted to a photocatalytic decarboxylation process of present interest.
International Nuclear Information System (INIS)
Ledermüller, Katrin; Schütz, Martin
2014-01-01
A multistate local CC2 response method for the calculation of analytic energy gradients with respect to nuclear displacements is presented for ground and electronically excited states. The gradient enables the search for equilibrium geometries of extended molecular systems. Laplace transform is used to partition the eigenvalue problem in order to obtain an effective singles eigenvalue problem and adaptive, state-specific local approximations. This leads to an approximation in the energy Lagrangian, which however is shown (by comparison with the corresponding gradient method without Laplace transform) to be of no concern for geometry optimizations. The accuracy of the local approximation is tested and the efficiency of the new code is demonstrated by application calculations devoted to a photocatalytic decarboxylation process of present interest
Excitation energy distributions in fusion reactions induced by Ar projectiles at 50 and 70 MeV/u
International Nuclear Information System (INIS)
Vient, E.; Badala, A.; Barbera, R.; Bizard, G.; Bougault, R.; Brou, R.; Cussol, D.; Colin, J.; Durand, D.; Drouet, A.; Horn, D.; Laville, J.L.; Le Brun, C.; Lecolley, J.F.; Leflecher, C.; Louvel, M.; Patry, J.P.; Peter, J.; Regimbart, R.; Steckmeyer, J.C.; Tamain, B.; Eudes, P.; Guilbault, F.; Lebrun, C.; Oubahadou, A.
1992-01-01
In the present experiment, we have studied the Ar+Ag system at two bombarding energies: 50 and 70 MeV/u. We have first focused on the standard decay of the corresponding hot nuclei, i.e. on the formation of evaporated residues, which have been detected in coincidence with most of the decay charged particles (use of a 4 π device). From this very complete knowledge of the events, it has been possible to determine the excitation energy distribution of the initial hot nuclei. In a second step of the analysis, we have extended the triggering conditions to more complicated events including multi-fragment emission. In section 2 of this paper, we describe the experimental set up. Section 3 is devoted to the results involving an evaporation residue. Section 4 is devoted to triggering conditions based on the multiplicity detected in the 4 π device. Section 5 is a summary of the results
International Nuclear Information System (INIS)
Yue Xiao-Le; Xu Wei; Zhang Ying; Wang Liang
2015-01-01
The piezomagnetoelastic energy harvester system subjected to harmonic and Poisson white noise excitations is studied by using the generalized cell mapping method. The transient and stationary probability density functions (PDFs) of response based on the global viewpoint are obtained by the matrix analysis method. Monte Carlo simulation results verify the accuracy of this method. It can be observed that evolutionary direction of transient and stationary PDFs is in accordance with the unstable manifold for this system, and a stochastic P-bifurcation occurs as the intensity of Poisson white noise increases. This study presents an efficient numerical tool to solve the stochastic response of a three-dimensional dynamical system and provides a new idea to analyze the energy harvester system. (paper)
Non-linear vibrating systems excited by a nonideal energy source with a large slope characteristic
González-Carbajal, Javier; Domínguez, Jaime
2017-11-01
This paper revisits the problem of an unbalanced motor attached to a fixed frame by means of a nonlinear spring and a linear damper. The excitation provided by the motor is, in general, nonideal, which means it is affected by the vibratory response. Since the system behaviour is highly dependent on the order of magnitude of the motor characteristic slope, the case of large slope is considered herein. Some Perturbation Methods are applied to the system of equations, which allows transforming the original 4D system into a much simpler 2D system. The fixed points of this reduced system and their stability are carefully studied. We find the existence of a Hopf bifurcation which, to the authors' knowledge, has not been addressed before in the literature. These analytical results are supported by numerical simulations. We also compare our approach and results with those published by other authors.
Directory of Open Access Journals (Sweden)
Mirosława Ostrowska
2012-11-01
Full Text Available A semi-empirical, physical models have been derived of the quantum yield ofthe deactivation processes (fluorescence, photosynthesis and heat productionof excited states in phytoplankton pigment molecules. Besides some alreadyknown models (photosynthesis and fluorescence, this novel approachincorporates the dependence of the dissipation yield of the excitation energyin phytoplankton pigment molecules on heat. The quantitative dependences ofthe quantum yields of these three processes on three fundamental parameters ofthe marine environment are defined: the chlorophyll concentration in the surface water layer Ca(0 (the basin trophicity,the irradiance PAR(z and the temperature temp(z at the study site.The model is complemented with two other relevant models describing thequantum yield of photosynthesis and of natural Sun-Induced Chlorophyll a Fluorescence (SICF in the sea, derived earlier by the author or with herparticipation on the basis of statistical analyses of a vast amount ofempirical material. The model described in the present paper enables theestimation of the quantum yields of phytoplankton pigment heat production forany region and season, in waters of any trophicity at different depths fromthe surface to depths of ca 60 m. The model can therefore be used to estimatethe yields of these deactivation processes in more than half the thickness ofthe euphotic zone in oligotrophic waters and in the whole thickness (anddeeper of this zone in mesotrophic and eutrophic waters. In particular theserelationships may be useful for a component analysis of the budget of lightenergy absorbed by phytoplankton pigments, namely, its utilization influorescence, photochemical quenching and nonphotochemical radiationlessdissipation - i.e. direct heat production.
Hot-electron-mediated desorption rates calculated from excited-state potential energy surfaces
DEFF Research Database (Denmark)
Olsen, Thomas; Gavnholt, Jeppe; Schiøtz, Jakob
2009-01-01
We present a model for desorption induced by (multiple) electronic transitions [DIET (DIMET)] based on potential energy surfaces calculated with the delta self-consistent field extension of density-functional theory. We calculate potential energy surfaces of CO and NO molecules adsorbed on variou...
Pancholi, S C
2011-01-01
By providing the reader with a foundational background in high spin nuclear structure physics and exploring exciting current discoveries in the field, this book presents new phenomena in a clear and compelling way. The quest for achieving the highest spin states has resulted in some remarkable successes which this monograph will address in comprehensive detail. The text covers an array of pertinent subject matter, including the rotational alignment and bandcrossings, magnetic rotation, triaxial strong deformation and wobbling motion and chirality in nuclei. Dr. Pancholi offers his readers a clearly-written and up-to-date treatment of the topics covered. The prerequisites for a proper appreciation are courses in nuclear physics and nuclear models and measurement techniques of observables like gamma-ray energies, intensities, multi-fold coincidences, angular correlations or distributions, linear polarization, internal conversion coefficients, short lifetime (pico-second range) of excited states etc. and instrum...
Daily energy expenditure in free-ranging Gopher Tortoises (Gopherus polyphemus)
Jodice, PGR; Epperson, DM; Visser, GH
2006-01-01
Studies of ecological energetics in chelonians are rare. Here, we report the first measurements of daily energy expenditure (DEE) and water influx rates (WIRS) in free-ranging adult Gopher Tortoises (Gopherus polyphemus). We used the doubly labeled water (DLW) method to measure DEE in six adult
Prospects for bioenergy use in Ghana using Long-range Energy Alternatives Planning model
DEFF Research Database (Denmark)
Kemausuor, Francis; Nygaard, Ivan; Mackenzie, Gordon A.
2015-01-01
biomass sources, through the production of biogas, liquid biofuels and electricity. Analysis was based on moderate and high use of bioenergy for transportation, electricity generation and residential fuel using the LEAP (Long-range Energy Alternatives Planning) model. Results obtained indicate...
Electronic excitation and Auger spectroscopy of hexamethyldissilane
International Nuclear Information System (INIS)
Souza, G.G.B. de; Azevedo e Souza, A.C. de; Martins, R.J.; Lucas, C.A.
1988-01-01
In this work, it is presented an spectroscopic study of Si 2 (CH 3 ) 6 which presents interesting characteristics in the Si - Si bond. Electron energy loss technique was used in the energy range of 500 - 200 eV for the electron beam. Electronic excitation spectra were obtained for the energy loss range from 5 to 30 eV, and also Auger spectra. (A.C.A.S.) [pt
Prospects for bioenergy use in Ghana using Long-range Energy Alternatives Planning model
International Nuclear Information System (INIS)
Kemausuor, Francis; Nygaard, Ivan; Mackenzie, Gordon
2015-01-01
As Ghana's economy grows, the choice of future energy paths and policies in the coming years will have a significant influence on its energy security. A Renewable Energy Act approved in 2011 seeks to encourage the influx of renewable energy sources in Ghana's energy mix. The new legal framework combined with increasing demand for energy has created an opportunity for dramatic changes in the way energy is generated in Ghana. However, the impending changes and their implication remain uncertain. This paper examines the extent to which future energy scenarios in Ghana could rely on energy from biomass sources, through the production of biogas, liquid biofuels and electricity. Analysis was based on moderate and high use of bioenergy for transportation, electricity generation and residential fuel using the LEAP (Long-range Energy Alternatives Planning) model. Results obtained indicate that introducing bioenergy to the energy mix could reduce GHG (greenhouse gas) emissions by about 6 million tonnes CO_2e by 2030, equivalent to a 14% reduction in a business-as-usual scenario. This paper advocates the use of second generation ethanol for transport, to the extent that it is economically exploitable. Resorting to first generation ethanol would require the allocation of over 580,000 ha of agricultural land for ethanol production. - Highlights: • This paper examines modern bioenergy contribution to Ghana's future energy mix. • Three scenarios are developed and analysed. • Opportunities exist for modern bioenergy to replace carbon intensive fuels. • Introducing modern bioenergy to the mix could result in a 14% reduction in GHG.
Managheb, S. A. M.; Ziaei-Rad, S.; Tikani, R.
2018-05-01
The coupling between polarization and strain gradients is called flexoelectricity. This phenomenon exists in all dielectrics with any symmetry. In this paper, energy harvesting from a Timoshenko beam is studied by considering the flexoelectric and strain gradient effects. General governing equations and related boundary conditions are derived using Hamilton's principle. The flexoelectric effects are defined by gradients of normal and shear strains which lead to a more general model. The developed model also covers the classical Timoshenko beam theory by ignoring the flexoelectric effect. Based on the developed model, flexoelectricity effect on dielectric beams and energy harvesting from cantilever beam under harmonic base excitation is investigated. A parametric study was conducted to evaluate the effects of flexoelectric coefficients, strain gradient constants, base acceleration and the attaching tip mass on the energy harvested from a cantilever Timoshenko beam. Results show that the flexoelectricity has a significant effect on the energy harvester performance, especially in submicron and nano scales. In addition, this effect makes the beam to behave softer than before and also it changes the harvester first resonance frequency. The present study provides guidance for flexoelectric nano-beam analysis and a method to evaluate the performance of energy harvester in nano-dielectric devices.
CMOS Active Pixel Sensors as energy-range detectors for proton Computed Tomography
International Nuclear Information System (INIS)
Esposito, M.; Waltham, C.; Allinson, N.M.; Anaxagoras, T.; Evans, P.M.; Poludniowski, G.; Green, S.; Parker, D.J.; Price, T.; Manolopoulos, S.; Nieto-Camero, J.
2015-01-01
Since the first proof of concept in the early 70s, a number of technologies has been proposed to perform proton CT (pCT), as a means of mapping tissue stopping power for accurate treatment planning in proton therapy. Previous prototypes of energy-range detectors for pCT have been mainly based on the use of scintillator-based calorimeters, to measure proton residual energy after passing through the patient. However, such an approach is limited by the need for only a single proton passing through the energy-range detector in a read-out cycle. A novel approach to this problem could be the use of pixelated detectors, where the independent read-out of each pixel allows to measure simultaneously the residual energy of a number of protons in the same read-out cycle, facilitating a faster and more efficient pCT scan. This paper investigates the suitability of CMOS Active Pixel Sensors (APSs) to track individual protons as they go through a number of CMOS layers, forming an energy-range telescope. Measurements performed at the iThemba Laboratories will be presented and analysed in terms of correlation, to confirm capability of proton tracking for CMOS APSs
CMOS Active Pixel Sensors as energy-range detectors for proton Computed Tomography.
Esposito, M; Anaxagoras, T; Evans, P M; Green, S; Manolopoulos, S; Nieto-Camero, J; Parker, D J; Poludniowski, G; Price, T; Waltham, C; Allinson, N M
2015-06-03
Since the first proof of concept in the early 70s, a number of technologies has been proposed to perform proton CT (pCT), as a means of mapping tissue stopping power for accurate treatment planning in proton therapy. Previous prototypes of energy-range detectors for pCT have been mainly based on the use of scintillator-based calorimeters, to measure proton residual energy after passing through the patient. However, such an approach is limited by the need for only a single proton passing through the energy-range detector in a read-out cycle. A novel approach to this problem could be the use of pixelated detectors, where the independent read-out of each pixel allows to measure simultaneously the residual energy of a number of protons in the same read-out cycle, facilitating a faster and more efficient pCT scan. This paper investigates the suitability of CMOS Active Pixel Sensors (APSs) to track individual protons as they go through a number of CMOS layers, forming an energy-range telescope. Measurements performed at the iThemba Laboratories will be presented and analysed in terms of correlation, to confirm capability of proton tracking for CMOS APSs.
Autonomous Vehicles Have a Wide Range of Possible Energy Impacts (Poster)
Energy Technology Data Exchange (ETDEWEB)
Brown, A.; Repac, B.; Gonder, J.
2013-07-01
This poster presents initial estimates of the net energy impacts of automated vehicles (AVs). Automated vehicle technologies are increasingly recognized as having potential to decrease carbon dioxide emissions and petroleum consumption through mechanisms such as improved efficiency, better routing, lower traffic congestion, and by enabling advanced technologies. However, some effects of AVs could conceivably increase fuel consumption through possible effects such as longer distances traveled, increased use of transportation by underserved groups, and increased travel speeds. The net effect on petroleum use and climate change is still uncertain. To make an aggregate system estimate, we first collect best estimates for the energy impacts of approximately ten effects of AVs. We then use a modified Kaya Identity approach to estimate the range of aggregate effects and avoid double counting. We find that depending on numerous factors, there is a wide range of potential energy impacts. Adoption of automated personal or shared vehicles can lead to significant fuel savings but has potential for backfire.
Dependence of the K x-ray energy on the mode of excitation
International Nuclear Information System (INIS)
Wang, K.C.; Boehm, F.; Hahn, A.A.; Vogel, P.
1977-01-01
The energy shifts in the Ta K x rays resulting from the K-capture of 181 W, fluorescence of Ta, and β - decay of 181 Hf followed by internal conversion in 181 Ta are reported. Both W metal and WO 3 on one hand, and Ta metal and Ta 2 O 5 on the other hand, were used. Comparison of the K x-ray energies of the K-capture sources 153 Gd (Eu x rays) and 175 Hf (Lu x rays) and the corresponding fluorescence sources was also made. Various effects which may influence the K x-ray energies are discussed. 9 references
Enriquez, Miriam M.; LaFountain, Amy M.; Budarz, James; Fuciman, Marcel; Gibson, George N.; Frank, Harry A.
2010-06-01
Steady-state and femtosecond time-resolved transient absorption spectra of diadinoxanthin and diatoxanthin were measured in the visible and near-infrared (NIR) regions at 293 K. The difference in energy between the visible S 0 → S 2 transitions from the steady-state absorption measurements and the S 1 → S 2 transitions observed in the transient absorption spectra in the NIR region yields precise values of the S 1 energies. The data are important for evaluating the mechanism by which excess energy is dissipated by algal systems that interconvert these xanthophylls in response to changes in photon flux levels in the marine environment.
DEFF Research Database (Denmark)
Sneskov, Kristian; Gras, Eduard Matito; Kongsted, Jacob
2010-01-01
as being applicable for averaging over many solvent configurations derived from, for example, molecular simulations. We test the proposed model using as a benchmark the two lowest-lying valence singlet excitations (n → π* and π → π*) of acrolein, formamide, and N-methylacetamide in aqueous solution as well...
Long-range Coulomb interactions in low energy (e,2e) data
International Nuclear Information System (INIS)
Waterhouse, D.
2000-01-01
Full text: Proper treatment of long-range Coulomb interactions has confounded atomic collision theory since Schrodinger first presented a quantum-mechanical model for atomic interactions. The long-range Coulomb interactions are difficult to include in models in a way that treats the interaction sufficiently well but at the same time ensures the calculation remains tractable. An innovative application of an existing multi-parameter (e,2e) data acquisition system will be described. To clarify the effects of long-range Coulomb interactions, we will report the correlations and interactions that occur at low energy, observed by studying the energy sharing between outgoing electrons in the electron-impact ionisation of krypton